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Sample records for absorption spectrom etry

  1. WIPP Benchmark calculations with the large strain SPECTROM codes

    SciTech Connect

    Callahan, G.D.; DeVries, K.L.

    1995-08-01

    This report provides calculational results from the updated Lagrangian structural finite-element programs SPECTROM-32 and SPECTROM-333 for the purpose of qualifying these codes to perform analyses of structural situations in the Waste Isolation Pilot Plant (WIPP). Results are presented for the Second WIPP Benchmark (Benchmark II) Problems and for a simplified heated room problem used in a parallel design calculation study. The Benchmark II problems consist of an isothermal room problem and a heated room problem. The stratigraphy involves 27 distinct geologic layers including ten clay seams of which four are modeled as frictionless sliding interfaces. The analyses of the Benchmark II problems consider a 10-year simulation period. The evaluation of nine structural codes used in the Benchmark II problems shows that inclusion of finite-strain effects is not as significant as observed for the simplified heated room problem, and a variety of finite-strain and small-strain formulations produced similar results. The simplified heated room problem provides stratigraphic complexity equivalent to the Benchmark II problems but neglects sliding along the clay seams. The simplified heated problem does, however, provide a calculational check case where the small strain-formulation produced room closures about 20 percent greater than those obtained using finite-strain formulations. A discussion is given of each of the solved problems, and the computational results are compared with available published results. In general, the results of the two SPECTROM large strain codes compare favorably with results from other codes used to solve the problems.

  2. Quantitative IR microscopy and spectromics open the way to 3D digital pathology.

    PubMed

    Bobroff, Vladimir; Chen, Hsiang-Hsin; Delugin, Maylis; Javerzat, Sophie; Petibois, Cyril

    2016-06-01

    Currently, only mass-spectrometry (MS) microscopy brings a quantitative analysis of chemical contents of tissue samples in 3D. Here, the reconstruction of a 3D quantitative chemical images of a biological tissue by FTIR spectro-microscopy is reported. An automated curve-fitting method is developed to extract all intense absorption bands constituting IR spectra. This innovation benefits from three critical features: (1) the correction of raw IR spectra to make them quantitatively comparable; (2) the automated and iterative data treatment allowing to transfer the IR-absorption spectrum into a IR-band spectrum; (3) the reconstruction of an 3D IR-band matrix (x, y, z for voxel position and a 4(th) dimension with all IR-band parameters). Spectromics, which is a new method for exploiting spectral data for tissue metadata reconstruction, is proposed to further translate the related chemical information in 3D, as biochemical and anatomical tissue parameters. An example is given with oxidative stress distribution and the reconstruction of blood vessels in tissues. The requirements of IR microscopy instrumentation to propose 3D digital histology as a clinical routine technology is briefly discussed.

  3. Un Détecteur de Neutrons pour la Spectrométrie de Masses Manquantes

    NASA Astrophysics Data System (ADS)

    Bollini, D.; Buhler-Broglin, A.; Dalpiaz, P.; Massam, T.; Navach, F.; Navarria, F. L.; Schneegans, M. A.; Zichichi, A.

    A large (2 × 0.39 m3 plastic scintillator) neutron detector capable to measure with high accuracy the coordinates of the neutron interaction point as well as its time-of-flight is described. As a missing mass spectrometer, it allows to observe for example the η, meson with a mass resolution of ± 4.2 MeV. Nous décrivous un détectcur de neutrons de grand volume sensible (2 x 0,39 m3 de scintillatcur plastique) capable de mesurer avec précision les coordonnées du point d'interaction du neutron détecté ainsi que son temp-de-vol. Employé comme spectrométre de masses manquantes, it permet d'observer par exemple le méson η avec une resolution de ± 4,2 MeY.

  4. Étude comparative des techniques d'analyse par fluorescence X à dispersion d'énergie (ED-XRF) et à dispersion de longueur d'onde (WD-XRF), et par spectrométrie d'émission atomique à source plasma couplée par induction (ICP-AES)

    NASA Astrophysics Data System (ADS)

    Rahmani, A.; Benyaïch, F.; Bounakhla, M.; Bilal, E.; Moutte, J.; Gruffat, J. J.; Zahry, F.

    2004-11-01

    Dans ce travail, nous présentons une étude comparative des techniques d'analyse par fluorescence X à dispersion d'énergie (ED-XRF) et à dispersion de longueur d'onde (WD-XRF), et par spectrométrie d'émission atomique à source plasma couplée par induction (ICP-AES). Les résultats de la calibration des spectromètres à dispersion d'énergie, à excitation par sources radioactives (55Fe, 109Cd et 241Am) et à excitation secondaire (cible secondaire Mo et Cu) du Centre National pour l'Energie, les Sciences et les Techniques Nucléaires (CNESTEN, Rabat, Maroc) sur des échantillons étalons de références de l'Agence International de l'Energie Atomique (AIEA) et du Community Bureau of Référence (BCR) ont été comparés aux résultats d'analyse des mêmes échantillons étalons par la spectrométrie X à dispersion de longueur d'onde (WD-XRF) et par spectrométrie d'émission atomique à source plasma couplé par induction (ICP-AES) au département GENERIC du centre SPIN à l'Ecole des Mines de Saint-Etienne (France). Les trois techniques d'analyse utilisées donnent des résultats comparables pour le dosage des éléments majeurs, alors que pour les traces on note des déviations importantes à cause des effets de matrice qui sont difficiles à corriger dans le cas de la fluorescence X.

  5. PERITONEAL ABSORPTION

    PubMed Central

    Hahn, P. F.; Miller, L. L.; Robscheit-Robbins, F. S.; Bale, W. F.; Whipple, G. H.

    1944-01-01

    The absorption of red cells from the normal peritoneum of the dog can be demonstrated by means of red cells labeled with radio-iron incorporated in the hemoglobin of these red cells. Absorption in normal dogs runs from 20 to 100 per cent of the amount given within 24 hours. Dogs rendered anemic by bleeding absorb red cells a little less rapidly—ranging from 5 to 80 per cent of the injected red cells. Doubly depleted dogs (anemic and hypoproteinemic) absorb even less in the three experiments recorded. This peritoneal absorption varies widely in different dogs and even in the same dog at different times. We do not know the factors responsible for these variations but there is no question about active peritoneal absorption. The intact red cells pass readily from the peritoneal cavity into lymph spaces in diaphragm and other areas of the peritoneum. The red cells move along the lymphatics and through the lymph glands with little or no phagocytosis and eventually into the large veins through the thoracic ducts. PMID:19871404

  6. Nutrient absorption.

    PubMed

    Rubin, Deborah C

    2004-03-01

    Our understanding of nutrient absorption continues to grow, from the development of unique animal models and from studies in which cutting-edge molecular and cellular biologic approaches have been used to analyze the structure and function of relevant molecules. Studies of the molecular genetics of inherited disorders have also provided many new insights into these processes. A major advance in lipid absorption has been the cloning and characterization of several intestinal acyl CoA:monoacylglycerol acyltransferases; these may provide new targets for antiobesity drug therapy. Studies of intestinal cholesterol absorption and reverse cholesterol transport have encouraged the development of novel potential treatments for hyperlipidemia. Observations in genetically modified mice and in humans with mutations in glucose transporter 2 suggest the importance of a separate microsomal membrane transport pathway for glucose transport. The study of iron metabolism has advanced greatly with the identification of the hemochromatosis gene and the continued examination of the genetic regulation of iron absorptive pathways. Several human thiamine transporters have been identified, and their specific roles in different tissues are being explored.

  7. ABSORPTION ANALYZER

    DOEpatents

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

    1961-11-14

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

  8. Atmospheric absorption cell characterization

    NASA Astrophysics Data System (ADS)

    1982-06-01

    The measurement capability of the Avionics Laboratory IR Facility was used to evaluate an absorption cell that will be used to simulate atmospheric absorption over horizontal paths of 1 - 10 km in length. Band models were used to characterize the transmittance of carbon dioxide (CO2), nitrogen (N2), and nitrous oxide (N2O) in the cell. The measured transmittance was compared to the calculated values. Nitrous oxide is important in the 4 - 4.5 micron range in shaping the weak line absorption of carbon dioxide. The absorption cell is adequate for simulating atmospheric absorption over these paths.

  9. Solar absorption surface panel

    DOEpatents

    Santala, Teuvo J.

    1978-01-01

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

  10. Rectal absorption of propylthiouracil.

    PubMed

    Bartle, W R; Walker, S E; Silverberg, J D

    1988-06-01

    The rectal absorption of propylthiouracil (PTU) was studied and compared to oral absorption in normal volunteers. Plasma levels of PTU after administration of suppositories of PTU base and PTU diethanolamine were significantly lower compared to the oral route. Elevated plasma reverse T3 levels were demonstrated after each treatment, however, suggesting a desirable therapeutic effect at this dosage level for all preparations.

  11. Petawatt laser absorption bounded

    PubMed Central

    Levy, Matthew C.; Wilks, Scott C.; Tabak, Max; Libby, Stephen B.; Baring, Matthew G.

    2014-01-01

    The interaction of petawatt (1015 W) lasers with solid matter forms the basis for advanced scientific applications such as table-top particle accelerators, ultrafast imaging systems and laser fusion. Key metrics for these applications relate to absorption, yet conditions in this regime are so nonlinear that it is often impossible to know the fraction of absorbed light f, and even the range of f is unknown. Here using a relativistic Rankine-Hugoniot-like analysis, we show for the first time that f exhibits a theoretical maximum and minimum. These bounds constrain nonlinear absorption mechanisms across the petawatt regime, forbidding high absorption values at low laser power and low absorption values at high laser power. For applications needing to circumvent the absorption bounds, these results will accelerate a shift from solid targets, towards structured and multilayer targets, and lead the development of new materials. PMID:24938656

  12. Quasar Absorption Studies

    NASA Technical Reports Server (NTRS)

    Mushotzky, Richard (Technical Monitor); Elvis, Martin

    2004-01-01

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

  13. Absorption heat pump system

    DOEpatents

    Grossman, G.

    1982-06-16

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

  14. Compounds affecting cholesterol absorption

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

  15. Soliton absorption spectroscopy

    PubMed Central

    Kalashnikov, V. L.; Sorokin, E.

    2010-01-01

    We analyze optical soliton propagation in the presence of weak absorption lines with much narrower linewidths as compared to the soliton spectrum width using the novel perturbation analysis technique based on an integral representation in the spectral domain. The stable soliton acquires spectral modulation that follows the associated index of refraction of the absorber. The model can be applied to ordinary soliton propagation and to an absorber inside a passively modelocked laser. In the latter case, a comparison with water vapor absorption in a femtosecond Cr:ZnSe laser yields a very good agreement with experiment. Compared to the conventional absorption measurement in a cell of the same length, the signal is increased by an order of magnitude. The obtained analytical expressions allow further improving of the sensitivity and spectroscopic accuracy making the soliton absorption spectroscopy a promising novel measurement technique. PMID:21151755

  16. Absorption heat pump system

    DOEpatents

    Grossman, Gershon

    1984-01-01

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

  17. Optical absorption measurement system

    DOEpatents

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

    1989-01-01

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

  18. Solar selective absorption coatings

    DOEpatents

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

    2003-10-14

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

  19. Solar selective absorption coatings

    DOEpatents

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

    2004-08-31

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

  20. Intranasal absorption of oxymorphone.

    PubMed

    Hussain, M A; Aungst, B J

    1997-08-01

    The nasal bioavailability of oxymorphone HCI was determined. Rats were surgically prepared to isolate the nasal cavity, into which a solution of oxymorphone was administered. A reference group of rats was administered oxymorphone HCl intravenously. Plasma oxymorphone concentrations were determined by HPLC. Nasal absorption was rapid, nasal bioavailability was 43%, and the iv and nasal elimination profiles were similar. Oxymorphone HCI appears to have the solubility, potency, and absorption properties required for efficient nasal delivery, which is an alternative to injections.

  1. Seven-effect absorption refrigeration

    DOEpatents

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

    1989-05-09

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

  2. Seven-effect absorption refrigeration

    DOEpatents

    DeVault, Robert C.; Biermann, Wendell J.

    1989-01-01

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

  3. Absorption heat pump system

    DOEpatents

    Grossman, Gershon; Perez-Blanco, Horacio

    1984-01-01

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

  4. Absorption Heat Pump Cycles

    NASA Astrophysics Data System (ADS)

    Kunugi, Yoshifumi; Kashiwagi, Takao

    Various advanced absorption cycles are studied, developed and invented. In this paper, their cycles are classified and arranged using the three categories: effect, stage and loop, then an outline of the cycles are explained on the Duehring diagram. Their cycles include high COP cycles for refrigerations and heat pumps, high temperature lift cycles for heat transformer, absorption-compression hybrid cycles and heat pump transformer cycle. The highest COPi is attained by the seven effect cycle. In addition, the cycles for low temperature are invented and explained. Furthermore the power generation • refrigeration cycles are illustrated.

  5. Two-Phonon Absorption

    ERIC Educational Resources Information Center

    Hamilton, M. W.

    2007-01-01

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

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

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

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

  7. Quantum absorption refrigerator.

    PubMed

    Levy, Amikam; Kosloff, Ronnie

    2012-02-17

    A quantum absorption refrigerator driven by noise is studied with the purpose of determining the limitations of cooling to absolute zero. The model consists of a working medium coupled simultaneously to hot, cold, and noise baths. Explicit expressions for the cooling power are obtained for Gaussian and Poisson white noise. The quantum model is consistent with the first and second laws of thermodynamics. The third law is quantified; the cooling power J(c) vanishes as J(c) ∝ T(c)(α), when T(c)→0, where α=d+1 for dissipation by emission and absorption of quanta described by a linear coupling to a thermal bosonic field, where d is the dimension of the bath.

  8. Acoustic absorption by sunspots

    NASA Technical Reports Server (NTRS)

    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.

  9. Bioacoustic Absorption Spectroscopy

    DTIC Science & Technology

    2016-06-07

    seas in co-operation with fisheries biologists. The first planned experiment will be in the seas off California in co-operation with the Southwest... Fisheries Science Center of NOAA’s National Marine Fisheries Service. These experiments will be designed to investigate the “signatures” of the two major...formulating environmental adaptation strategies for tactical sonars. Fisheries applications: These results suggest that bioacoustic absorptivity can be used to

  10. Vehicular impact absorption system

    NASA Technical Reports Server (NTRS)

    Knoell, A. C.; Wilson, A. H. (Inventor)

    1978-01-01

    An improved vehicular impact absorption system characterized by a plurality of aligned crash cushions of substantially cubic configuration is described. Each consists of a plurality of voided aluminum beverage cans arranged in substantial parallelism within a plurality of superimposed tiers and a covering envelope formed of metal hardware cloth. A plurality of cables is extended through the cushions in substantial parallelism with an axis of alignment for the cushions adapted to be anchored at each of the opposite end thereof.

  11. Hydrogen Absorption by Niobium.

    DTIC Science & Technology

    1982-04-13

    incorporate an independent means for ascertaining surface cleanliness (e.g. AES). The form of the absorption curve in Fig. 7 appears to agree with that...very interesting study and is well within the capabilities of the systen designed, if the surface cleanliness can be assured. Wire specimens have a...assessing surface cleanliness would be an important supporting technique for understanding the results of these measurements. The simple kinetic

  12. Relic Neutrino Absorption Spectroscopy

    SciTech Connect

    Eberle, b

    2004-01-28

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

  13. Corrosion Problems in Absorption Chillers

    ERIC Educational Resources Information Center

    Stetson, Bruce

    1978-01-01

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

  14. Acoustic Absorption Characteristics of People.

    ERIC Educational Resources Information Center

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

    1968-01-01

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

  15. Ultraviolet absorption hygrometer

    DOEpatents

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

    1986-01-01

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

  16. Ultraviolet absorption hygrometer

    DOEpatents

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

    1986-12-09

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

  17. Modular total absorption spectrometer

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

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

  18. The HI absorption "Zoo"

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  19. Analyzing Water's Optical Absorption

    NASA Technical Reports Server (NTRS)

    2002-01-01

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

  20. Differential optoacoustic absorption detector

    NASA Technical Reports Server (NTRS)

    Shumate, M. S. (Inventor)

    1978-01-01

    A differential optoacoustic absorption detector employed two tapered cells in tandem or in parallel. When operated in tandem, two mirrors were used at one end remote from the source of the beam of light directed into one cell back through the other, and a lens to focus the light beam into the one cell at a principal focus half way between the reflecting mirror. Each cell was tapered to conform to the shape of the beam so that the volume of one was the same as for the other, and the volume of each received maximum illumination. The axes of the cells were placed as close to each other as possible in order to connect a differential pressure detector to the cells with connecting passages of minimum length. An alternative arrangement employed a beam splitter and two lenses to operate the cells in parallel.

  1. Two absorption furosemide prodrugs.

    PubMed

    Mombrú, A W; Mariezcurrena, R A; Suescun, L; Pardo, H; Manta, E; Prandi, C

    1999-03-15

    The structures of two absorption furosemide prodrugs, hexanoyloxymethyl 4-chloro-N-furfuryl-5-sulfamoyl-anthranilate (C19H23CIN2O7S), (I), and benzoyloxymethyl 4-chloro-N-furfuryl-5-sulfamoylanthranilate (C20H17CIN2O7S), (II), are described in this paper and compared with furosemide and four other prodrugs. The molecular conformations of both compounds are similar to those of the other prodrugs; the packing and the crystal system are the primary differences. Compound (I) crystallizes in the trigonal space group R3 and compound (II) in the monoclinic space group P2(1)/n. The packing of both structures is stabilized by a three-dimensional hydrogen-bond network.

  2. X-ray Absorption Spectroscopy

    SciTech Connect

    Yano, Junko; Yachandra, Vittal K.

    2009-07-09

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

  3. BASIC STUDIES IN PERCUTANEOUS ABSORPTION.

    DTIC Science & Technology

    FATTY ACIDS, *SKIN(ANATOMY), ABSORPTION, ALKYL RADICALS, AMIDES, DIFFUSION, ELECTRON MICROSCOPY, HUMIDITY, LABORATORY ANIMALS, LIPIDS, ORGANIC SOLVENTS, PENETRATION, PRIVATION, PROTEINS, RATS, TEMPERATURE, WATER

  4. Solar Absorption in Cloudy Atmospheres

    NASA Technical Reports Server (NTRS)

    Harshvardhan; Ridgway, William; Ramaswamy, V.; Freidenreich, S. M.; Batey, Michael

    1996-01-01

    The theoretical computations used to compute spectral absorption of solar radiation are discussed. Radiative properties relevant to the cloud absorption problem are presented and placed in the context of radiative forcing. Implications for future measuring programs and the effect of horizontal inhomogeneities are discussed.

  5. Atmospheric absorption of sound - Update

    NASA Technical Reports Server (NTRS)

    Bass, H. E.; Sutherland, L. C.; Zuckerwar, A. J.

    1990-01-01

    Best current expressions for the vibrational relaxation times of oxygen and nitrogen in the atmosphere are used to compute total absorption. The resulting graphs of total absorption as a function of frequency for different humidities should be used in lieu of the graph published earlier by Evans et al (1972).

  6. Subgap Absorption in Conjugated Polymers

    DOE R&D Accomplishments Database

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

    1991-01-01

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

  7. Optical absorption of silicon nanowires

    SciTech Connect

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

    2012-08-01

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

  8. Ultraviolet absorption spectrum of HOCl

    NASA Technical Reports Server (NTRS)

    Burkholder, James B.

    1993-01-01

    The room temperature UV absorption spectrum of HOCl was measured over the wavelength range 200 to 380 nm with a diode array spectrometer. The absorption spectrum was identified from UV absorption spectra recorded following UV photolysis of equilibrium mixtures of Cl2O/H2O/HOCl. The HOCl spectrum is continuous with a maximum at 242 nm and a secondary peak at 304 nm. The measured absorption cross section at 242 nm was (2.1 +/- 0.3) x 10 exp -19/sq cm (2 sigma error limits). These results are in excellent agreement with the work of Knauth et al. (1979) but in poor agreement with the more recent measurements of Mishalanie et al. (1986) and Permien et al. (1988). An HOCl nu2 infrared band intensity of 230 +/- 35/sq cm atm was determined based on this UV absorption cross section. The present results are compared with these previous measurements and the discrepancies are discussed.

  9. Gas-absorption process

    DOEpatents

    Stephenson, Michael J.; Eby, Robert S.

    1978-01-01

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

  10. Gastrointestinal citrate absorption in nephrolithiasis

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  11. Microwave radiation absorption: behavioral effects.

    PubMed

    D'Andrea, J A

    1991-07-01

    The literature contains much evidence that absorption of microwave energy will lead to behavioral changes in man and laboratory animals. The changes include simple perturbations or outright stoppage of ongoing behavior. On one extreme, intense microwave absorption can result in seizures followed by death. On the other extreme, man and animals can hear microwave pulses at very low rates of absorption. Under certain conditions of exposure, animals will avoid microwaves, while under other conditions, they will actively work to obtain warmth produced by microwaves. Some research has shown behavioral effects during chronic exposure to low-level microwaves. The specific absorption rates that produce behavioral effects seem to depend on microwave frequency, but controversy exists over thresholds and mechanism of action. In all cases, however, the behavioral disruptions cease when chronic microwave exposure is terminated. Thermal changes in man and animals during microwave exposure appear to account for all reported behavioral effects.

  12. Incomplete intestinal absorption of fructose.

    PubMed Central

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

    1984-01-01

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

  13. Reflective-tube absorption meter

    NASA Astrophysics Data System (ADS)

    Zaneveld, J. Ronald V.; Bartz, Robert; Kitchen, James C.

    1990-09-01

    The design and calibration of a proposed in situ spectral absorption meter is evaluated using a laboratory prototype. The design includes a silver coated (second-surface) glass tube, a tungsten light source (stabilized by means of optical feedback), a monochromator, and a solid state detector. The device measures the absorption coefficient plus a portion of the volume scattering function. Theoretical analyses and laboratory experiments which explore the magnitude and variation of the errors due to scattering and internal reflections are described. Similar analyses are performed on the Cary 1 18 Spectrophotometer to allow cross calibration. Algorithms to yield the abscrption coefficient and the zenith-sun diffuse attenuation coefficient are presented and evaluated. Simultaneous measurement of the beam attenuation or backscattering coefficient allows use of algoriThms with much narrower error bands. The various methods of obtaining absorption and diffuse attenuation values are compared. Procedures for using reverse osmosis filtration to produce a clean water calibration standard are described. An absorption spectrum for pure water is obtained. Development of the absorption meter is proceeding along two lines: 1) a two-wavelength side-by-side LED is being fabricated to allow an in situ chlorophyll a absorption meter to be constructed, and 2) scientific projects using a shipboard or laboratory flow.-through pumping system are being planned.

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

    PubMed

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

    2015-04-01

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

  15. Absorption and Metabolism of Xanthophylls

    PubMed Central

    Kotake-Nara, Eiichi; Nagao, Akihiko

    2011-01-01

    Dietary carotenoids, especially xanthophylls, have attracted significant attention because of their characteristic biological activities, including anti-allergic, anti-cancer, and anti-obese actions. Although no less than forty carotenoids are ingested under usual dietary habits, only six carotenoids and their metabolites have been found in human tissues, suggesting selectivity in the intestinal absorption of carotenoids. Recently, facilitated diffusion in addition to simple diffusion has been reported to mediate the intestinal absorption of carotenoids in mammals. The selective absorption of carotenoids may be caused by uptake to the intestinal epithelia by the facilitated diffusion and an unknown excretion to intestinal lumen. It is well known that β-carotene can be metabolized to vitamin A after intestinal absorption of carotenoids, but little is known about the metabolic transformation of non provitamin A xanthophylls. The enzymatic oxidation of the secondary hydroxyl group leading to keto-carotenoids would occur as a common pathway of xanthophyll metabolism in mammals. This paper reviews the absorption and metabolism of xanthophylls by introducing recent advances in this field. PMID:21747746

  16. Enhanced absorption cycle computer model

    NASA Astrophysics Data System (ADS)

    Grossman, G.; Wilk, M.

    1993-09-01

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

  17. Absorption-heat-pump system

    DOEpatents

    Grossman, G.; Perez-Blanco, H.

    1983-06-16

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

  18. Transient absorption spectroscopy of laser shocked explosives

    SciTech Connect

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

    2010-01-01

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

  19. Aerosol Absorption Measurements in MILAGRO.

    NASA Astrophysics Data System (ADS)

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

    2007-12-01

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

  20. Metal powder absorptivity: Modeling and experiment

    DOE PAGES

    Boley, C. D.; Mitchell, S. C.; Rubenchik, A. M.; ...

    2016-08-10

    Here, we present results of numerical modeling and direct calorimetric measurements of the powder absorptivity for a number of metals. The modeling results generally correlate well with experiment. We show that the powder absorptivity is determined, to a great extent, by the absorptivity of a flat surface at normal incidence. Our results allow the prediction of the powder absorptivity from normal flat-surface absorptivity measurements.

  1. Theory of graphene saturable absorption

    NASA Astrophysics Data System (ADS)

    Marini, A.; Cox, J. D.; García de Abajo, F. J.

    2017-03-01

    Saturable absorption is a nonperturbative 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 semianalytical nonperturbative single-particle approach, describing 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 nonperturbatively, 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. We obtain results in qualitative agreement with atomistic quantum-mechanical simulations of graphene nanoribbons including electron-electron interactions, finite-size, and higher-band effects. Remarkably, such effects are found to affect mainly the linear absorption, while the predicted saturation intensities are in good quantitative agreement in the limit of extended graphene. Additionally, we find that the modulation depth of saturable absorption in graphene can be electrically manipulated through an externally applied gate voltage. Our results are relevant for the development of graphene-based optoelectronic devices, as well as for applications in mode-locking and random lasers.

  2. Migrant labor absorption in Malaysia.

    PubMed

    Nayagam, J

    1992-01-01

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

  3. Quasistellar Objects: Intervening Absorption Lines

    NASA Astrophysics Data System (ADS)

    Charlton, J.; Churchill, C.; Murdin, P.

    2000-11-01

    Every parcel of gas along the line of sight to a distant QUASAR will selectively absorb certain wavelengths of continuum light of the quasar due to the presence of the various chemical elements in the gas. Through the analysis of these quasar absorption lines we can study the spatial distributions, motions, chemical enrichment and ionization histories of gaseous structures from REDSHIFT five unti...

  4. Oxygen Absorption in Cooling Flows.

    PubMed

    Buote

    2000-04-01

    The inhomogeneous cooling flow scenario predicts the existence of large quantities of gas in massive elliptical galaxies, groups, and clusters that have cooled and dropped out of the flow. Using spatially resolved, deprojected X-ray spectra from the ROSAT PSPC, we have detected strong absorption over energies approximately 0.4-0.8 keV intrinsic to the central approximately 1&arcmin; of the galaxy NGC 1399, the group NGC 5044, and the cluster A1795. These systems have among the largest nearby cooling flows in their respective classes and low Galactic columns. Since no excess absorption is indicated for energies below approximately 0.4 keV, the most reasonable model for the absorber is warm, collisionally ionized gas with T=105-106 K in which ionized states of oxygen provide most of the absorption. Attributing the absorption only to ionized gas reconciles the large columns of cold H and He inferred from Einstein and ASCA with the lack of such columns inferred from ROSAT and also is consistent with the negligible atomic and molecular H inferred from H i and CO observations of cooling flows. The prediction of warm ionized gas as the product of mass dropout in these and other cooling flows can be verified by Chandra and X-Ray Multimirror Mission.

  5. Neutron Absorption in Geological Material

    NASA Astrophysics Data System (ADS)

    Løvhøiden, G.; Andersen, E.

    1990-01-01

    Thermal neutron absorption cross section of geological samples is determined with the steady state neutron source method. Cross section measurements of North Sea sediments demonstrate that also materials with high contents of clay minerals may be investigated with the steady state method.

  6. Ultraviolet and Light Absorption Spectrometry.

    ERIC Educational Resources Information Center

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

    1984-01-01

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

  7. Slow light and saturable absorption

    NASA Astrophysics Data System (ADS)

    Selden, A. C.

    2009-06-01

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

  8. Light Absorption By Coated Soot

    NASA Astrophysics Data System (ADS)

    Sedlacek, A. J.; Lee, J.; Onasch, T. B.; Davidovits, P.; Cross, E. S.

    2009-12-01

    The contribution of aerosol absorption on direct radiative forcing is still an active area of research, in part, because aerosol extinction is dominated by light scattering and, in part, because the primary absorbing aerosol of interest, soot, exhibits complex aging behavior that alters its optical properties. The consequences of this can be evidenced by the work of Ramanathan and Carmichael (2008) who suggest that incorporating the atmospheric heating due to brown clouds will increase black carbon (BC) radiative forcing from the IPCC best estimate of 0.34 Wm-2 (±0.25 Wm-2) (IPCC 2007) to 0.9 Wm-2. This noteworthy degree of the uncertainty is due largely to the interdependence of BC optical properties on particle mixing state and aggregate morphology, each of which changes as the particle ages in the atmosphere and becomes encapsulated within a coating of inorganic and/or organic substances. With the advent of techniques that can directly measure aerosol light absorption without influences due to collection substrate or light scattering (e.g., photoacoustic spectroscopy (Arnott et al., 2005; Lack et al., 2006) and photothermal interferometry (Sedlacek and Lee 2007)) the potential exists for quantifying this interdependence. In July 2008, a laboratory-based measurement campaign, led by Boston College and Aerodyne, was initiated to begin addressing this interdependence. To achieve this objective measurements of both the optical and physical properties of flame-generated soot under nascent, coated and denuded conditions were conducted. In this paper, light absorption by dioctyl sebacate (DOS) encapsulated soot and sulfuric acid coated soot using the technique of photothermal interferometry will be presented. In the case of DOS-coated soot, a monotonic increase in light absorption as a function DOS coating thickness to nearly 100% is observed. This observation is consistent with a coating-induced amplification in particle light absorption. (Bond et al. 2006) However

  9. Optical absorptions of polyfluorene transistors

    NASA Astrophysics Data System (ADS)

    Deng, Yvonne Y.; Sirringhaus, Henning

    2005-07-01

    Conjugated polymers are a promising class of materials for organic electronics. While the progress in device performance is impressive, the basics of charge transport still pose many open questions. Specifically, conduction at the comparatively rough polymer-polymer interface in an all-polymer field-effect transistor is expected to be different from a sharp interface with an inorganic dielectric, such as silicon dioxide. In this work, charge modulation spectroscopy (CMS) is used to study the optical absorptions in the presence of charges in situ in the transistor structure. This allows direct observation of the charge carriers in the operational device via their spectroscopic signature; the technique is by design very sensitive to the properties of the semiconductor-dielectric interface. The semiconducting copolymer poly( 9,9' -dioctyl-fluorene-co-bithiophene) (F8T2) is incorporated into a top-gate thin-film transistor structure with a polymer dielectric layer deposited by spin coating and inkjet-printed polymer electrodes. A prominent charge-induced absorption at 1.65eV is observed as well as a shoulder at 1.3eV and a tail extending toward the absorption edge. The bias dependence of the CMS signature confirms that intermixing of the polymer layers is minimal, as expected from the excellent transistor characteristics. Polarization-dependent CMS measurements on aligned transistors show that the main feature at 1.65eV is strongly polarized whereas the shoulder is unpolarized. This observation, as well as further experimental evidence, lead to the conclusion that while the main absorption is attributable to the intrinsic, polaronic absorption in F8T2, the shoulder is likely to originate from a defect state.

  10. Infrasound absorption by atmospheric clouds

    NASA Astrophysics Data System (ADS)

    Baudoin, Michael; Coulouvrat, Francois; Thomas, Jean-Louis

    2010-05-01

    A model is developed for the absorption of infrasound by atmospheric clouds made of a suspension of liquid water droplets within a gaseous mixture of water vapor and air. The model is based on the work of D.A. Gubaidullin and R.I. Nigmatulin [Int. J. Multiphase Flow, 26, 207-228, 2000], which is applied to atmospheric clouds. Three physical mechanisms are included : unsteady viscous drag associated with momentum transfers due to the translation of water droplets, unsteady thermal transfers between the liquid and gaseous phases, and mass transfers due to the evaporation or condensation of the water phase. For clouds, in the infrasonic frequency range, phase changes are the dominant mechanisms (around 1 Hz), while viscous and heat transfers become significant only around 100 Hz. Mass transfers involve two physical effects : evaporation and condensation of the water phase at the droplet surface, and diffusion of the water vapor within the gaseous phase. The first one is described through the Hertz-Knudsen-Langmuir theory based on kinetic theory. It involves a little known coefficient known as coefficient of accommodation. The second one is the classical Fick diffusion. For clouds, and unless the coefficient of accommodation is very small (far from the generally recommended value is close to one), diffusion is the main limiting effects for mass transfers. In a second stage, the sound and infrasound absorption is evaluated for various typical clouds up to about 4 km altitude. Above this altitude, the ice content of clouds is dominant compared to their water content, and the present model is not applicable. Cloud thickness, water content, and droplets size distribution are shown to be the major factors influencing the infrasound absorption. A variety of clouds have been analyzed. In most cases, it is shown that infrasound absorption within clouds is several orders larger than classical absorption (due to molecular relaxation of nitrogen and oxygen molecules in presence

  11. Iodine Absorption Cells Purity Testing.

    PubMed

    Hrabina, Jan; Zucco, Massimo; Philippe, Charles; Pham, Tuan Minh; Holá, Miroslava; Acef, Ouali; Lazar, Josef; Číp, Ondřej

    2017-01-06

    This article deals with the evaluation of the chemical purity of iodine-filled absorption cells and the optical frequency references used for the frequency locking of laser standards. We summarize the recent trends and progress in absorption cell technology and we focus on methods for iodine cell purity testing. We compare two independent experimental systems based on the laser-induced fluorescence method, showing an improvement of measurement uncertainty by introducing a compensation system reducing unwanted influences. We show the advantages of this technique, which is relatively simple and does not require extensive hardware equipment. As an alternative to the traditionally used methods we propose an approach of hyperfine transitions' spectral linewidth measurement. The key characteristic of this method is demonstrated on a set of testing iodine cells. The relationship between laser-induced fluorescence and transition linewidth methods will be presented as well as a summary of the advantages and disadvantages of the proposed technique (in comparison with traditional measurement approaches).

  12. Landing gear energy absorption system

    NASA Technical Reports Server (NTRS)

    Hansen, Christopher P. (Inventor)

    1994-01-01

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

  13. The Intestinal Absorption of Folates

    PubMed Central

    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

  14. Optical absorption in trilayer graphene

    NASA Astrophysics Data System (ADS)

    Li, Xiao; Zhang, Fan; Niu, Qian

    2013-03-01

    We use a low energy effective model to analyze the optical responses of trilayer graphene samples. We first show that optical absorption of the ABA-stacked trilayer has strong dependence on both the Fermi energy and optical frequency, which is in sharp contrast to that of ABC-stacked trilayer graphene. Secondly, we are able to determine the possible existence of trigonal warping effects in the bandstructure of ABC-stacked trilayer graphene by a divergence in the absorption spectra at around 10 meV. In addition, we can partially distinguish the vairious broken symmetry states driven by electron-electron interactions in ABC-stacked trilayer graphene. In particular, the quantum anomalous Hall (QAH) state is sensitive to the polarization of the incident light, giving a way to detect its possible existence.

  15. Optical Absorption Characteristics of Aerosols.

    DTIC Science & Technology

    1985-09-11

    properties of the powder as well as the thickness of the layer. For a layer that is thick enough so that no light is transmitted, the Kubelka -- Munk theory...which is a two stream radiative transfer model, relates the reflectance to the ratio of the absorption to the scattering. The Kubelka - Munk theory has...of the aerosol material is known. Under the assumptions of the Kubelka - Munk . theory, the imaginary component of the refractive index is deter- mined

  16. Photodetector with enhanced light absorption

    DOEpatents

    Kane, James

    1985-01-01

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

  17. Geometrical interpretation of optical absorption

    SciTech Connect

    Monzon, J. J.; Barriuso, A. G.; Sanchez-Soto, L. L.; Montesinos-Amilibia, J. M.

    2011-08-15

    We reinterpret the transfer matrix for an absorbing system in very simple geometrical terms. In appropriate variables, the system appears as performing a Lorentz transformation in a (1 + 3)-dimensional space. Using homogeneous coordinates, we map that action on the unit sphere, which is at the realm of the Klein model of hyperbolic geometry. The effects of absorption appear then as a loxodromic transformation, that is, a rhumb line crossing all the meridians at the same angle.

  18. Absorption Spectroscopy in Homogeneous and Micellar Solutions.

    ERIC Educational Resources Information Center

    Shah, S. Sadiq; Henscheid, Leonard G.

    1983-01-01

    Describes an experiment which has helped physical chemistry students learn principles of absorption spectroscopy, the effect of solvent polarity on absorption spectra, and some micellar chemistry. Background information and experimental procedures are provided. (JN)

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

    ERIC Educational Resources Information Center

    Mathes, Eugene W.; And Others

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

  20. Glucagon receptor antagonism induces increased cholesterol absorption[S

    PubMed Central

    Guan, Hong-Ping; Yang, Xiaodong; Lu, Ku; Wang, Sheng-Ping; Castro-Perez, Jose M.; Previs, Stephen; Wright, Michael; Shah, Vinit; Herath, Kithsiri; Xie, Dan; Szeto, Daphne; Forrest, Gail; Xiao, Jing Chen; Palyha, Oksana; Sun, Li-Ping; Andryuk, Paula J.; Engel, Samuel S.; Xiong, Yusheng; Lin, Songnian; Kelley, David E.; Erion, Mark D.; Davis, Harry R.; Wang, Liangsu

    2015-01-01

    Glucagon and insulin have opposing action in governing glucose homeostasis. In type 2 diabetes mellitus (T2DM), plasma glucagon is characteristically elevated, contributing to increased gluconeogenesis and hyperglycemia. Therefore, glucagon receptor (GCGR) antagonism has been proposed as a pharmacologic approach to treat T2DM. In support of this concept, a potent small-molecule GCGR antagonist (GRA), MK-0893, demonstrated dose-dependent efficacy to reduce hyperglycemia, with an HbA1c reduction of 1.5% at the 80 mg dose for 12 weeks in T2DM. However, GRA treatment was associated with dose-dependent elevation of plasma LDL-cholesterol (LDL-c). The current studies investigated the cause for increased LDL-c. We report findings that link MK-0893 with increased glucagon-like peptide 2 and cholesterol absorption. There was not, however, a GRA-related modulation of cholesterol synthesis. These findings were replicated using structurally diverse GRAs. To examine potential pharmacologic mitigation, coadministration of ezetimibe (a potent inhibitor of cholesterol absorption) in mice abrogated the GRA-associated increase of LDL-c. Although the molecular mechanism is unknown, our results provide a novel finding by which glucagon and, hence, GCGR antagonism govern cholesterol metabolism. PMID:26373568

  1. Advanced regenerative absorption refrigeration cycles

    DOEpatents

    Dao, Kim

    1990-01-01

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

  2. Energy Absorption of Composite Materials.

    DTIC Science & Technology

    1983-03-01

    34 tion in a helicopter crash is accomplished Foye , et al. [4 an 5] examlnei th, primarily through three mechanisms; strok- energy absorption chara"tr...irar [3] and Foye , et al. [4]. No significant o. ’, energy release was obse:’viV-cirur, i m: rcg . . the Gr/FE tubes s .. 0T Fu!.A 4r /-e 45rK r5 1...K/E, GI/E, hybrid com- posite tubes and aluminum tubes. The 5. R. L. Foye , and W. T. H,.dg, " r following statements are based on results Results from

  3. Carbon Dioxide Absorption Heat Pump

    NASA Technical Reports Server (NTRS)

    Jones, Jack A. (Inventor)

    2002-01-01

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

  4. NEUTRON ABSORPTION AND SHIELDING DEVICE

    DOEpatents

    Axelrad, I.R.

    1960-06-21

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

  5. Tunneling induced absorption with competing Nonlinearities

    PubMed Central

    Peng, Yandong; Yang, Aihong; Xu, Yan; Wang, Peng; Yu, Yang; Guo, Hongju; Ren, Tingqi

    2016-01-01

    We investigate tunneling induced nonlinear absorption phenomena in a coupled quantum-dot system. Resonant tunneling causes constructive interference in the nonlinear absorption that leads to an increase of more than an order of magnitude over the maximum absorption in a coupled quantum dot system without tunneling. Resonant tunneling also leads to a narrowing of the linewidth of the absorption peak to a sublinewidth level. Analytical expressions show that the enhanced nonlinear absorption is largely due to the fifth-order nonlinear term. Competition between third- and fifth-order nonlinearities leads to an anomalous dispersion of the total susceptibility. PMID:27958303

  6. Absorption of CO laser radiation by NO

    NASA Technical Reports Server (NTRS)

    Hanson, R. K.; Monat, J. P.; Kruger, C. H.

    1976-01-01

    The paper describes absorption calculations and measurements at selected infrared CO laser wavelengths which are nearly coincident with absorption lines in the fundamental vibration-rotation band of NO near 5.3 microns. Initial work was directed towards establishing the optimal CO laser-NO absorption line coincidence for high temperature applications. Measurements of the absorption coefficient at this optimal laser wavelength were carried out, first using a room-temperature absorption cell for high-temperature calculations and then using a shock tube, for the temperature range 630-4000 K, to validate the high temperature calculations.

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

    PubMed Central

    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 absorption processes are largely determined by the one-photon absorption strength, whereas all even-photon absorption strengths are largely dominated by the two-photon absorption strength, in both cases modulated by powers of the polarizability of the final excited state. We demonstrate how to selectively enhance a specific multiphoton absorption process. PMID:26120588

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

    PubMed

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

    2015-05-20

    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 absorption processes are largely determined by the one-photon absorption strength, whereas all even-photon absorption strengths are largely dominated by the two-photon absorption strength, in both cases modulated by powers of the polarizability of the final excited state. We demonstrate how to selectively enhance a specific multiphoton absorption process.

  9. Sulphate absorption across biological membranes.

    PubMed

    Mitchell, Stephen C; Waring, Rosemary H

    2016-01-01

    1. Sulphonation is unusual amongst the common Phase II (condensation; synthetic) reactions experienced by xenobiotics, in that the availability of the conjugating agent, sulphate, may become a rate-limiting factor. This sulphate is derived within the body via the oxygenation of sulphur moieties liberated from numerous ingested compounds including the sulphur-containing amino acids. Preformed inorganic sulphate also makes a considerable contribution to this pool. 2. There has been a divergence of opinion as to whether or not inorganic sulphate may be readily absorbed from the gastrointestinal tract and this controversy still continues in some quarters. Even more so, is the vexing question of potential absorption of inorganic sulphate via the lungs and through the skin. 3. This review examines the relevant diverse literature and concludes that sulphate ions may move across biological membranes by means of specific transporters and, although the gastrointestinal tract is by far the major portal of entry, some absorption across the lungs and the skin may take place under appropriate circumstances.

  10. Formaldehyde Absorption toward W51

    SciTech Connect

    Kogut, A.; Smoot, G.F.; Bennett, C.L.; Petuchowski, S.J.

    1988-04-01

    We have measured formaldehyde (H{sub 2}CO) absorption toward the HII region complex W51A (G49.5-0.4) in the 6 cm and 2 cm wavelength rotational transitions with angular resolution of approximately 4 inch. The continuum HII region shows a large, previously undetected shell structure 5.5 pc along the major axis. We observe no H{sub 2}CO emission in regions of low continuum intensity. The absorption, converted to optical depth, shows a higher degree of clumping than previous maps at lower resolution. The good S/N of the maps allows accurate estimation of the complicated line profiles, showing some of the absorbing clouds to be quite patchy. We list the properties of the opacity spectra for a number of positions both in the clumps and in the more diffuse regions of the absorbing clouds, and derive column densities for the 1{sub 11} and 2{sub 12} rotational levels of ortho-formaldehyde.

  11. QED-driven laser absorption

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

    Absorption covers the physical processes which convert intense photon flux into energetic particles when a high-power laser (I >1018 W cm-2 where I is intensity at 1 μm wavelength) illuminates optically-thick matter. It underpins important applications of petawatt laser systems today, e.g., in isochoric heating of materials. Next-generation lasers such as ELI are anticipated to produce quantum electrodynamical (QED) bursts of γ-rays and anti-matter via the multiphoton Breit-Wheeler process which could enable scaled laboratory probes, e.g., of black hole winds. Here, applying strong-field QED to advances in plasma kinematic theory, we present a model elucidating absorption limited only by an avalanche of self-created electron-positron pairs at ultra-high-field. The model, confirmed by multidimensional QED-PIC simulations, works over six orders of magnitude in optical intensity and reveals this cascade is initiated at 1.8 x 1025 W cm-2 using a realistic linearly-polarized laser pulse. Here the laser couples its energy into highly-collimated electrons, ions, γ-rays, and positrons at 12%, 6%, 58% and 13% efficiency, respectively. We remark on attributes of the QED plasma state and possible applications.

  12. Iodine Absorption Cells Purity Testing

    PubMed Central

    Hrabina, Jan; Zucco, Massimo; Philippe, Charles; Pham, Tuan Minh; Holá, Miroslava; Acef, Ouali; Lazar, Josef; Číp, Ondřej

    2017-01-01

    This article deals with the evaluation of the chemical purity of iodine-filled absorption cells and the optical frequency references used for the frequency locking of laser standards. We summarize the recent trends and progress in absorption cell technology and we focus on methods for iodine cell purity testing. We compare two independent experimental systems based on the laser-induced fluorescence method, showing an improvement of measurement uncertainty by introducing a compensation system reducing unwanted influences. We show the advantages of this technique, which is relatively simple and does not require extensive hardware equipment. As an alternative to the traditionally used methods we propose an approach of hyperfine transitions’ spectral linewidth measurement. The key characteristic of this method is demonstrated on a set of testing iodine cells. The relationship between laser-induced fluorescence and transition linewidth methods will be presented as well as a summary of the advantages and disadvantages of the proposed technique (in comparison with traditional measurement approaches). PMID:28067834

  13. Iron Absorption in Drosophila melanogaster

    PubMed Central

    Mandilaras, Konstantinos; Pathmanathan, Tharse; Missirlis, Fanis

    2013-01-01

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

  14. Iron absorption in Drosophila melanogaster.

    PubMed

    Mandilaras, Konstantinos; Pathmanathan, Tharse; Missirlis, Fanis

    2013-05-17

    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.

  15. Absorption in Extended Inhomogeneous Clouds

    NASA Technical Reports Server (NTRS)

    Joiner, Joanna; Vasilkov, Alexander; Spurr, Robert; Bhartia, P. K.; Krotkov, Nick

    2008-01-01

    The launch of several different sensors, including CloudSat, into the A-train constellation of satellites allows us for the first time to compute absorption that can occur in realistic vertically inhomogeneous clouds including multiple cloud decks. CloudSat data show that these situations are common. Therefore, understanding vertically inhomogeneous clouds is important from both climate and satellite atmospheric composition remote sensing perspectives. Satellite passive sensors that operate from the near IR to the UV often rely on radiative cloud pressures derived from absorption in oxygen bands (A, B, gamma, or O2-O2 bands) or from rotational-Raman scattering in order to retrieve information about atmospheric trace gases. The radiative cloud pressure is distinct from the physical cloud top derived from thermal infrared measurements. Therefore, the combination of information from different passive sensors yields some information about the cloud vertical profile. When either or both the clouds or atmospheric absorbers (trace gases and aerosols) are vertically inhomogeneous, the use of an effective cloud pressure derived from these approaches may lead to errors. Here, we focus on several scenarios (deep convective clouds and distinct two layer clouds) based on realistic cloud optical depth vertical profiles derived from the CloudSatfMODIS combination. We focus on implications for trace-gas column amount retrievals (specifically ozone and NO2) and derived surface UV irradiance from the Ozone Monitoring Instrument (OMI) on the Atrain Aura platform.

  16. Energy absorption of composite materials

    NASA Technical Reports Server (NTRS)

    Farley, G. L.

    1983-01-01

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

  17. Assessing the absorption of new pharmaceuticals.

    PubMed

    Hidalgo, I J

    2001-11-01

    The advent of more efficient methods to synthesize and screen new chemical compounds is increasing the number of chemical leads identified in the drug discovery phase. Compounds with good biological activity may fail to become drugs due to insufficient oral absorption. Selection of drug development candidates with adequate absorption characteristics should increase the probability of success in the development phase. To assess the absorption potential of new chemical entities numerous in vitro and in vivo model systems have been used. Many laboratories rely on cell culture models of intestinal permeability such as, Caco-2, HT-29 and MDCK. To attempt to increase the throughput of permeability measurements, several physicochemical methods such as, immobilized artificial membrane (IAM) columns and parallel artificial membrane permeation assay (PAMPA) have been used. More recently, much attention has been given to the development of computational methods to predict drug absorption. However, it is clear that no single method will sufficient for studying drug absorption, but most likely a combination of systems will be needed. Higher throughput, less reliable methods could be used to discover 'loser' compounds, whereas lower throughput, more accurate methods could be used to optimize the absorption properties of lead compounds. Finally, accurate methods are needed to understand absorption mechanisms (efflux-limited absorption, carrier-mediated, intestinal metabolism) that may limit intestinal drug absorption. This information could be extremely valuable to medicinal chemists in the selection of favorable chemo-types. This review describes different techniques used for evaluating drug absorption and indicates their advantages and disadvantages.

  18. Computer programs for absorption spectrophotometry.

    PubMed

    Jones, R N

    1969-03-01

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

  19. Backscatter absorption gas imaging system

    DOEpatents

    McRae, T.G. Jr.

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

  20. Backscatter absorption gas imaging system

    DOEpatents

    McRae, Jr., Thomas G.

    1985-01-01

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

  1. HI Absorption in Merger Remnants

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  2. Multistage quantum absorption heat pumps

    NASA Astrophysics Data System (ADS)

    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.

  3. Multistage quantum absorption heat pumps.

    PubMed

    Correa, Luis A

    2014-04-01

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

  4. Quantum-enhanced absorption refrigerators

    PubMed Central

    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

  5. Acoustic Absorption in Porous Materials

    NASA Technical Reports Server (NTRS)

    Kuczmarski, Maria A.; Johnston, James C.

    2011-01-01

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

  6. Quantum-enhanced absorption refrigerators

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

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

  7. Analysis of frequency dependent pump light absorption

    NASA Astrophysics Data System (ADS)

    Wohlmuth, Matthias; Pflaum, Christoph

    2011-03-01

    Simulations have to accurately model thermal lensing in order to help improving resonator design of diode pumped solid state lasers. To this end, a precise description of the pump light absorption is an important prerequisite. In this paper, we discuss the frequency dependency of the pump light absorption in the laser crystal and its influence on the simulated laser performance. The results show that the pump light absorption has to include the spectral overlap of the emitting pump source and the absorbing laser material. This information can either be used for a fully frequency dependent absorption model or, at least in the shown examples, to compute an effective value for an exponential Beer-Lambert law of absorption. This is particularly significant at pump wavelengths coinciding with a peak of absorption. Consequences for laser stability and performance are analyzed for different pump wavelengths in a Nd:YAG laser.

  8. Studies of cavity enhanced absorption spectroscopy for weak absorption gas measurements

    NASA Astrophysics Data System (ADS)

    Li, Liucheng; Duo, Liping; Gong, Deyu; Ma, Yanhua; Zhang, Zhiguo; Wang, Yuanhu; Zhou, Dongjian; Jin, Yuqi

    2017-01-01

    In order to determine the concentrations of trace amount metastable species in chemical lasers, an off-axis cavity enhanced absorption spectrometer for the detection of weak absorption gases has been built with a noise equivalent absorption sensitivity of 1.6x10-8 cm-1. The absorption spectrum of trace amount gaseous ammonia and water vapor was obtained with a spectral resolution of about 78 MHz. A multiple-line absorption spectroscopic method to determine the temperature of gaseous ammonia has been developed by use of multiple lines of ammonia molecule absorption spectrum.

  9. Atomic absorption spectroscopy in ion channel screening.

    PubMed

    Stankovich, Larisa; Wicks, David; Despotovski, Sasko; Liang, Dong

    2004-10-01

    This article examines the utility of atomic absorption spectroscopy, in conjunction with cold flux assays, to ion channel screening. The multiplicity of ion channels that can be interrogated using cold flux assays and atomic absorption spectroscopy is summarized. The importance of atomic absorption spectroscopy as a screening tool is further elaborated upon by providing examples of the relevance of ion channels to various physiological processes and targeted diseases.

  10. Absorption Coefficient of Alkaline Earth Halides.

    DTIC Science & Technology

    1980-04-01

    levels . As a natural consequence, the magnitude of the absorption coefficient is the key parameter in selecting laser window materials. Over the past...of as can be achieved through improved crystal growing techniques and surface polishing. 2.5. Urbach’s Rule A central question for the development of...high absorption levels , inaccuracies progressively increasing with decreasing absorption level , a natural consequence of decreasing in instrumental

  11. Neural regulation of intestinal nutrient absorption.

    PubMed

    Mourad, Fadi H; Saadé, Nayef E

    2011-10-01

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

  12. Sulphur trioxide absorption apparatus and process

    SciTech Connect

    Cameron, G.M.

    1987-03-31

    This patent describes a contact process for producing a concentrated sulphuric acid from dry sulphur dioxide and oxygen containing mixtures which employs the absorption of sulphur trioxide from a hot, dry gas stream containing sulphur trioxide into at least one sulphuric acid stream. The improvement described here comprises: (a) feeding the gas stream to a lower packed absorption zone contained within an absorption tower; (b) feeding a first sulphuric acid stream to the lower absorption zone to effect absorption of a major portion of the sulphur trioxide from the gas stream into the first sulphuric acid stream to produce a first enriched sulphuric acid stream and a depleted sulphur trioxide gas stream; (c) feeding the depleted sulphur trioxide gas stream to an upper packed absorption zone above the lower absorption zone within the tower; and (d) feeding a second sulphuric acid stream to the upper absorption zone to effect absorption of substantially all of the sulphur trioxide remaining in the depleted sulphur trioxide gas stream to produce a second enriched sulphuric acid stream and a substantially sulphur trioxide-free gas stream.

  13. Study of Evanescence Wave Absorption in Lindane

    NASA Astrophysics Data System (ADS)

    Marzuki, A.; Prasetyo, E.; Gitrin, M. P.; Suryanti, V.

    2017-02-01

    Evanescent wave field has been studied for the purpose of tailoring fiber sensor capable of detecting lindane concentration in a solution. The mounted fiber was optically polished such that part of the fiber clad is stripped off. To study the evanescent wave field absorption in lindane solution, the unclad fiber was immersed in the solution. Light coming out of the fiber was studied at different wavelength each for different lindane concentration. It was shown that evanescent wave field absorption is stronger at wavelength corresponding to lindane absorption band as has been shown from absorption studies lindane in UV-VIS-NIR spectrophotometer.

  14. Terahertz wave absorption via preformed air plasma

    NASA Astrophysics Data System (ADS)

    Zhao, Ji; Zhang, LiangLiang; Wu, Tong; Zhang, CunLin; Zhao, YueJin

    2016-12-01

    Terahertz wave generation from laser-induced air plasma has continued to be an exciting field of research over the course of the past decade. In this paper, we report on an investigation concerning terahertz wave absorption with preformed plasma created by another laser pulse. We examine terahertz absorption behavior by varying the pump power and then analyze the polarization effect of the preplasma beam on terahertz wave absorption. The results of experiments conducted in which a type-I beta barium borate (BBO) crystal is placed before the preformed air plasma indicate that the fundamental (ω) and second harmonic (2ω) pulses can also influence terahertz absorption.

  15. Fluid absorption solar energy receiver

    NASA Technical Reports Server (NTRS)

    Bair, Edward J.

    1993-01-01

    A conventional solar dynamic system transmits solar energy to the flowing fluid of a thermodynamic cycle through structures which contain the gas and thermal energy storage material. Such a heat transfer mechanism dictates that the structure operate at a higher temperature than the fluid. This investigation reports on a fluid absorption receiver where only a part of the solar energy is transmitted to the structure. The other part is absorbed directly by the fluid. By proportioning these two heat transfer paths the energy to the structure can preheat the fluid, while the energy absorbed directly by the fluid raises the fluid to its final working temperature. The surface temperatures need not exceed the output temperature of the fluid. This makes the output temperature of the gas the maximum temperature in the system. The gas can have local maximum temperatures higher than the output working temperature. However local high temperatures are quickly equilibrated, and since the gas does not emit radiation, local high temperatures do not result in a radiative heat loss. Thermal radiation, thermal conductivity, and heat exchange with the gas all help equilibrate the surface temperature.

  16. The absorption of polymeric composites

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  17. Do Atoms Really "Emit" Absorption Lines?

    ERIC Educational Resources Information Center

    Brecher, Kenneth

    1991-01-01

    Presents three absorption line sources that enhance student understanding of the phenomena associated with the interaction of light with matter and help dispel the misconception that atoms "emit" absorption lines. Sources include neodymium, food coloring and other common household liquids, and fluorescent materials. (MDH)

  18. Iron absorption from intrinsically-labeled lentils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Low iron (Fe) absorption from important staple foods may contribute to Fe deficiency in developing countries. To date, there are few studies examining the Fe bioavailability of pulse crops as commonly prepared and consumed by humans. The objectives of this study were to characterize the Fe absorpt...

  19. A Low-Cost Quantitative Absorption Spectrophotometer

    ERIC Educational Resources Information Center

    Albert, Daniel R.; Todt, Michael A.; Davis, H. Floyd

    2012-01-01

    In an effort to make absorption spectrophotometry available to high school chemistry and physics classes, we have designed an inexpensive visible light absorption spectrophotometer. The spectrophotometer was constructed using LEGO blocks, a light emitting diode, optical elements (including a lens), a slide-mounted diffraction grating, and a…

  20. Atmospheric Solar Heating in Minor Absorption Bands

    NASA Technical Reports Server (NTRS)

    Chou, Ming-Dah

    1998-01-01

    Solar radiation is the primary source of energy driving atmospheric and oceanic circulations. Concerned with the huge computing time required for computing radiative transfer in weather and climate models, solar heating in minor absorption bands has often been neglected. The individual contributions of these minor bands to the atmospheric heating is small, but collectively they are not negligible. The solar heating in minor bands includes the absorption due to water vapor in the photosynthetically active radiation (PAR) spectral region from 14284/cm to 25000/cm, the ozone absorption and Rayleigh scattering in the near infrared, as well as the O2 and CO2 absorption in a number of weak bands. Detailed high spectral- and angular-resolution calculations show that the total effect of these minor absorption is to enhance the atmospheric solar heating by approximately 10%. Depending upon the strength of the absorption and the overlapping among gaseous absorption, different approaches are applied to parameterize these minor absorption. The parameterizations are accurate and require little extra time for computing radiative fluxes. They have been efficiently implemented in the various atmospheric models at NASA/Goddard Space Flight Center, including cloud ensemble, mesoscale, and climate models.

  1. Low absorptance porcelain-on-aluminum coating

    NASA Technical Reports Server (NTRS)

    Leggett, H.

    1979-01-01

    Porcelain thermal-control coating for aluminum sheet and foil has solar absorptance of 0.22. Specially formulated coating absorptance is highly stable, changing only 0.03 after 1,000 hours of exposure to simulated sunlight and can be applied by standard commercial methods.

  2. Energy Absorption Behaviors of Nanoporous Systems

    DTIC Science & Technology

    2005-01-01

    energy absorption isotherms : (a) the first loading-unloading cycle; (b) the second, the third, and the fourth loading-unloading cycles without thermal...change, AV (cm- /g) Fig.7 The energy absorption isotherms under a cyclic loading in a 23. lwt% aqueous solution of NaC1. 80

  3. Absorption imaging of a single atom

    NASA Astrophysics Data System (ADS)

    Streed, Erik W.; Jechow, Andreas; Norton, Benjamin G.; Kielpinski, David

    2012-07-01

    Absorption imaging has played a key role in the advancement of science from van Leeuwenhoek's discovery of red blood cells to modern observations of dust clouds in stellar nebulas and Bose-Einstein condensates. Here we show the first absorption imaging of a single atom isolated in a vacuum. The optical properties of atoms are thoroughly understood, so a single atom is an ideal system for testing the limits of absorption imaging. A single atomic ion was confined in an RF Paul trap and the absorption imaged at near wavelength resolution with a phase Fresnel lens. The observed image contrast of 3.1 (3)% is the maximum theoretically allowed for the imaging resolution of our set-up. The absorption of photons by single atoms is of immediate interest for quantum information processing. Our results also point out new opportunities in imaging of light-sensitive samples both in the optical and X-ray regimes.

  4. Absorption imaging of a single atom.

    PubMed

    Streed, Erik W; Jechow, Andreas; Norton, Benjamin G; Kielpinski, David

    2012-07-03

    Absorption imaging has played a key role in the advancement of science from van Leeuwenhoek's discovery of red blood cells to modern observations of dust clouds in stellar nebulas and Bose-Einstein condensates. Here we show the first absorption imaging of a single atom isolated in a vacuum. The optical properties of atoms are thoroughly understood, so a single atom is an ideal system for testing the limits of absorption imaging. A single atomic ion was confined in an RF Paul trap and the absorption imaged at near wavelength resolution with a phase Fresnel lens. The observed image contrast of 3.1 (3)% is the maximum theoretically allowed for the imaging resolution of our set-up. The absorption of photons by single atoms is of immediate interest for quantum information processing. Our results also point out new opportunities in imaging of light-sensitive samples both in the optical and X-ray regimes.

  5. [Effect of altitude on iron absorption].

    PubMed

    Pizarro, F; Zavaleta, N; Hertrampf, E; Berlanga, R; Camborda, L; Olivares, M

    1998-03-01

    Iron bioavailability was evaluated in people living in high altitudes. Absorption was estimated from a reference dose of ferrous ascorbate and from a standard diet of wheat flour, using extrinsic tag radioisotope technique of 55Fe and 59Fe. Twenty four volunteers, healthy women, with ages ranging from 28 to 45 years, participated. Of those, eleven lived at 3450 meters above sea level (m.a.s.l.) in Huancayo city-Peru (study group), and 13 lived in Santiago de Chile at 630 m.a.s.l. (control group). Iron absorption from reference dose of ferrous ascorbate was 32.0% and 31.1% in the study and control groups respectively. The geometric mean of iron absorption from the standard diet, corrected to 40% of absorption of reference dose, was 9.0% and 6.9% in the study and control groups respectively (NS). The results suggest that altitude does not produce a high iron absorption in highlander residents.

  6. Creating semiconductor metafilms with designer absorption spectra

    PubMed Central

    Kim, Soo Jin; Fan, Pengyu; Kang, Ju-Hyung; Brongersma, Mark L.

    2015-01-01

    The optical properties of semiconductors are typically considered intrinsic and fixed. Here we leverage the rapid developments in the field of optical metamaterials to create ultrathin semiconductor metafilms with designer absorption spectra. We show how such metafilms can be constructed by placing one or more types of high-index semiconductor antennas into a dense array with subwavelength spacings. It is argued that the large absorption cross-section of semiconductor antennas and their weak near-field coupling open a unique opportunity to create strongly absorbing metafilms whose spectral absorption properties directly reflect those of the individual antennas. Using experiments and simulations, we demonstrate that near-unity absorption at one or more target wavelengths of interest can be achieved in a sub-50-nm-thick metafilm using judiciously sized and spaced Ge nanobeams. The ability to create semiconductor metafilms with custom absorption spectra opens up new design strategies for planar optoelectronic devices and solar cells. PMID:26184335

  7. Novel absorption detection techniques for capillary electrophoresis

    SciTech Connect

    Xue, Yongjun

    1994-07-27

    Capillary electrophoresis (CE) has emerged as one of the most versatile separation methods. However, efficient separation is not sufficient unless coupled to adequate detection. The narrow inner diameter (I.D.) of the capillary column raises a big challenge to detection methods. For UV-vis absorption detection, the concentration sensitivity is only at the μM level. Most commercial CE instruments are equipped with incoherent UV-vis lamps. Low-brightness, instability and inefficient coupling of the light source with the capillary limit the further improvement of UV-vis absorption detection in CE. The goals of this research have been to show the utility of laser-based absorption detection. The approaches involve: on-column double-beam laser absorption detection and its application to the detection of small ions and proteins, and absorption detection with the bubble-shaped flow cell.

  8. Near-infrared absorptions of monomethylhydrazine

    NASA Technical Reports Server (NTRS)

    Murray, Mark; Kurtz, Joe

    1993-01-01

    The peak absorption coefficients for two near-infrared absorptions of monomethylhydrazine, CH3-N2H3, (MMH) were measured. Absorption bands located at 1.524 micrometers (6560/cm), 1.557 micrometers (6423/cm), and 1.583 micrometers (6316/cm) are assigned to the Delta upsilon = 2 overtones of the infared N-H stretching fundamentals at 3317, 3245 and 3177/cm. An absorption band located at 1.04 micrometers (9620 +/- 100/cm) is assigned to the Delta upsilon = 3 overtone of one of these fundamentals. The peak absorption coefficients (alpha(sub 10)) at 1.524 micrometers (6560 +/- 20/cm) and 1.04 micrometers (9620 +/- 100/cm) are 31 x 10(exp -3) and 0.97 x 10(exp -3)/(cm atm), respectively. Uncertainties in these coefficients were estimated to be less than +/- 20% due primarily to uncertainties in the partial vapor pressure of MMH.

  9. Time-dependent oral absorption models

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  10. Absorption-Line Studies of Seyfert Galaxies

    NASA Astrophysics Data System (ADS)

    Shull, J. Michael

    We propose to undertake a "reverberation analysis" of the variable absorption lines ill two Seyfert Galaxies (NGC 4051 and Mrk 279) to help understand the origin of intrinsic absorption lines in AGNs. Stich an analysis is a powerful tool for elucidating the radial distribution of absorbing gas in the broad-line region (BLR) and narrow-line region (NLR). Only two Seyferts have previously been studied with this technique: NGC 4151 (Bromage el al. 1985; Clavel et al. 1987) and NGC 3516 (Voit, Shull, and Begelman 1987). The absorption features have been interpreted as an outflow of ionized clouds from the nuclear region or from an accretion disk affected by UV/X-ray heating. Neither the source of the absorbing gas in these Seyferts nor the "gene" which distingishes them from other Seyferts is known. Until the 1984 onset of absorption in Mrk 279, broad self-absorbed. lines had been observed only in Seyferts of low intrinsic luminosity, such as NGC 4051. Mrk 279 is intrinsically much brighter, and therefore more quasar-like, than the other three absorptionline Seyfert I's in the CfA sample. Thus, it may show how the absorption phenomenon changes at higher luminosity and could bridge the gap between the low luminosity absorption-line Seyferts and the well-studied broad absorption-line (BAL) QSO's. In addition, Mrk 279's significant redshift will allow us to study, for the first time, the Ly-alpha line in an absorption-line Seyfert. With 3 US-1 shifts for each of these two underobserved Seyferts, we can double the number of objects in which absorption-line variability has been studied and investigate why the absorption-line strengths correlate or anti-correlate with the UV continuum.

  11. Lactose enhances mineral absorption in infancy.

    PubMed

    Ziegler, E E; Fomon, S J

    1983-05-01

    To determine if lactose promotes the intestinal absorption of calcium and other minerals by infants, metabolic balance studies were performed with infants fed two formulas nearly identical in composition except for carbohydrate. One contained only lactose and the other contained sucrose and corn starch hydrolysate. Each of six normal infants had two balance studies performed with each formula in alternating sequence. When lactose was the carbohydrate, net absorption and net retention of calcium were significantly greater than when lactose was not present in the formula. Absorptions of magnesium and manganese were also significantly enhanced by lactose. Absorptions of copper and zinc were somewhat greater (not statistically significant) when lactose was present, whereas absorption of iron was not affected. Absorption of phosphorus was not different, but urinary excretion was less when the lactose containing formula was fed and, hence, net retention of phosphorus was significantly enhanced. These results confirm findings from animal studies and previous human studies and show that, in infants, lactose has a significant and sustained promoting effect on absorption of calcium and other minerals.

  12. The effect of tea on iron absorption.

    PubMed Central

    Disler, P B; Lynch, S R; Charlton, R W; Torrance, J D; Bothwell, T H; Walker, R B; Mayet, F

    1975-01-01

    The effect of tea on iron absorption was studied in human volunteers. Absorption from solutions of FeCl3 and FeSO4, bread, a meal of rice with potato and onion soup, and uncooked haemoglobin was inhibited whether ascorbic acid was present or not. No inhibition was noted if the haemoglobin was cooked. The effect on the absorption of non-haem iron was ascribed to the formation of insoluble iron tannate complexes. Drinking tannin-containing beverages such as tea with meals may contribute to the pathogenesis of iron deficiency if the diet consists largely of vegetable foodstuffs. PMID:1168162

  13. Selective coherent perfect absorption in metamaterials

    SciTech Connect

    Nie, Guangyu; Shi, Quanchao; Zhu, Zheng; Shi, Jinhui

    2014-11-17

    We show multi-band coherent perfect absorption (CPA) in simple bilayered asymmetrically split ring metamaterials. The selectivity of absorption can be accomplished by separately excited electric and magnetic modes in a standing wave formed by two coherent counterpropagating beams. In particular, each CPA can be completely switched on/off by the phase of a second coherent wave. We propose a practical scheme for realizing multi-band coherent perfect absorption of 100% that is allowed to work from microwave to optical frequency.

  14. Not-so-resonant, resonant absorption

    NASA Astrophysics Data System (ADS)

    Brunel, F.

    1987-07-01

    When an intense electromagnetic wave is incident obliquely on a sharply bounded overdense plasma, strong energy absorption can be accounted for by the electrons that are dragged into the vacuum and sent back into the plasma with velocities v~=vosc. This mechanism is more efficient than usual resonant absorption for vosc/ω>L, with L being the density gradient length. In the very high-intensity CO2-laser-target interaction, this mechanism may account for most of the energy absorption.

  15. Total absorption by degenerate critical coupling

    SciTech Connect

    Piper, Jessica R. Liu, Victor; Fan, Shanhui

    2014-06-23

    We consider a mirror-symmetric resonator with two ports. We show that, when excited from a single port, complete absorption can be achieved through critical coupling to degenerate resonances with opposite symmetry. Moreover, any time two resonances with opposite symmetry are degenerate in frequency and absorption is always significantly enhanced. In contrast, when two resonances with the same symmetry are nearly degenerate, there is no absorption enhancement. We numerically demonstrate these effects using a graphene monolayer on top of a photonic crystal slab, illuminated from a single side in the near-infrared.

  16. The gastrointestinal absorption of the actinide elements.

    PubMed

    Harrison, J D

    1991-03-01

    The greatest uncertainty in dose estimates for the ingestion of long-lived, alpha-emitting isotopes of the actinide elements is in the values used for their fractional absorption from the gastrointestinal tract (f1 values). Recent years have seen a large increase in the available data on actinide absorption. Human data are reviewed here, together with animal data, to illustrate the effect on absorption of chemical form, incorporation into food materials, fasting and other dietary factors, and age at ingestion. The f1 values recommended by the International Commission on Radiological Protection, by an Expert Group of the Nuclear Energy Agency and by the National Radiological Protection Board are discussed.

  17. Absorption of surface acoustic waves by graphene

    NASA Astrophysics Data System (ADS)

    Zhang, S. H.; Xu, W.

    2011-06-01

    We present a theoretical study on interactions of electrons in graphene with surface acoustic waves (SAWs). We find that owing to momentum and energy conservation laws, the electronic transition accompanied by the SAW absorption cannot be achieved via inter-band transition channels in graphene. For graphene, strong absorption of SAWs can be observed in a wide frequency range up to terahertz at room temperature. The intensity of SAW absorption by graphene depends strongly on temperature and can be adjusted by changing the carrier density. This study is relevant to the exploration of the acoustic properties of graphene and to the application of graphene as frequency-tunable SAW devices.

  18. Molar Absorptivity Measurements in Absorbing Solvents: Impact on Solvent Absorptivity Values.

    PubMed

    Bohman, Ariel; Arnold, Mark A

    2016-10-18

    Molar absorptivity is a fundamental molecular property that quantifies absorption strength as a function of wavelength. Absolute measurements of molar absorptivity demand accounting for all mechanisms of light attenuation, including reflective losses at interfaces associated with the sample. Ideally, such measurements are performed in nonabsorbing solvents and reflective losses can be determined in a straightforward manner from Fresnel equations or effectively accounted for by path length difference methods. At near-infrared wavelengths, however, many solvents, including water, are absorbing which complicates the quantification of reflective losses. Here, generalized equations are developed for calculating absolute molar absorptivities of neat liquids wherein the dependency of reflective loss on absorption properties of the liquid are considered explicitly. The resulting equations are used to characterize sensitivity of absolute molar absorptivity measurements for solvents to the absorption strength of the solvent as well as the path length of the measurement. Methods are derived from these equations to properly account for reflective losses in general and the effectiveness of these methods is demonstrated for absolute molar absorptivity measurements for water over the combination region (5000-4000 cm(-1)) of the near-infrared spectrum. Results indicate that ignoring solvent absorption effects can incorporate wide ranging systematic errors depending upon experimental conditions. As an example, systematic errors range from 0 to 10% for common conditions used in the measurement of absolute molar absorptivity of water over the combination region of the near-infrared spectrum.

  19. Electromagnetically induced absorption via incoherent collisions

    SciTech Connect

    Yang Xihua; Sheng Jiteng; Xiao Min

    2011-10-15

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

  20. Induced Transparency and Absorption in Coupled Microresonators

    NASA Technical Reports Server (NTRS)

    Smith, David D.; Chang, Hongrok

    2004-01-01

    We review the conditions for the occurrence of coherence phenomena in passive coupled optical microresonators. We derive the effective steady-state response and determine conditions for induced transparency and absorption in these systems.

  1. Terahertz absorption spectra of highly energetic chemicals

    NASA Astrophysics Data System (ADS)

    Slingerland, E. J.; Vallon, M. K.; Jahngen, E. G. E.; Giles, R. H.; Goyette, T. M.

    2010-04-01

    Research into absorption spectra is useful for detecting chemicals in the field. Each molecule absorbs a set of specific frequencies, which are dependent on the molecule's structure. While theoretical models are available for predicting the absorption frequencies of a particular molecule, experimental measurements are a more reliable method of determining a molecule's actual absorption behavior. The goal of this research is to explore chemical markers (absorption frequencies) that can be used to identify highly energetic molecules of interest to the remote sensing community. Particular attention was paid to the frequency ranges located within the terahertz transmission windows of the atmosphere. In addition, theoretical derivations, with the purpose of calculating the detection limits of such chemicals, will also be presented.

  2. Performance Analysis of Solution Transportation Absorption Chiller

    NASA Astrophysics Data System (ADS)

    Kiani, Behdad; Hamamoto, Yoshinori; Akisawa, Atsushi; Kashiwagi, Takao

    Thermally activated advanced absorption cycles are considered promising candidates to replace CFCs, HCFCs and HFCs for residential and commercial applications. In such absorption systems, it is desirable to utilize the waste heat from industries for heating and cooling applications in commercial and residential sectors. For this purpose, it is necessary to transport energy over some distance because the waste heat source and demand are generally located apart from each other. Transportation of steam, hot water or chilled water requires high construction costs for insulation. There is an efficient method of energy transportation using absorption system called “ Solution Transportation Absorption System (STA)”. The solution is transported at an ambient temperature so that tube-insulations not required. This paper shows the simulation of the abovementioned system and the optimal result, using mathematical optimization. The optimum system with industry‧s waste heat utilization is obtained. At the end, the effect on the pollution emission and energy conservation is obtained.

  3. Absorption chillers: Part of the solution

    SciTech Connect

    Occhionero, A.J. ); Hughes, P.J. ); Reid, E.A. )

    1991-01-01

    Acid rain, ozone depletion, global warming, and implementation economics are considered as they relate to the advisability of expanding the application of absorption chillers. Introductory and background information are provided to put the discussion in the proper context. Then all four issues are discussed separately as they relate to absorption chillers. Acid rain and ozone depletion concerns, and implementation economics, are found to support the expanded use of absorption chillers. The global warming concern is found to be more of a gray area, but the areas of benefit correspond well with the conditions of greatest economic advantage. All things considered, absorption chillers are believed to be part of the environmental and economic solution. It is further believed that integrated resource planning (IRP) processes that consider electric and gas technologies on an equal footing would come to the same conclusion for many regions of the United States. 9 refs., 3 tabs.

  4. The Absorption Spectrum of Sodium Vapor

    ERIC Educational Resources Information Center

    Ashby, R. A.; Gotthard, H. W.

    1974-01-01

    Procedures and discussion of an experiment to be used in an undergraduate course in spectroscopy are presented. The experiment involves the measurement of the absorption spectrum of sodium vapor. (DT)

  5. Optical absorption coefficients of pure water

    NASA Astrophysics Data System (ADS)

    Lu, Zheng; Zhao, Xianzhen; Fry, Edward S.

    2002-10-01

    The integrating cavity absorption meter(ICAM), which is independent of scattering effect, is used to measure the absolute values of small optical absorption coefficients of liquid. A modified ICAM is being used to measure the absorption of water in the wavelength range 300 to 700 nm. The ultrapure water produced by a two-stages water purification system reaches Type I quality. This is equal to or better than ASTM,CAP and NCCLS water quality standards. To avoid the fact that dissolved oxygen absorbs ultraviolet light due to the photochemical effect, the water sample is delivered through a nitrogen sealed system which will prevent the sample from contacting with oxygen. A compassion of our absorption spectrum with other existing data is given.

  6. Theory of absorption-induced transparency

    NASA Astrophysics Data System (ADS)

    Rodrigo, Sergio G.; García-Vidal, F. J.; Martín-Moreno, L.

    2013-10-01

    Recent experiments [Hutchison, O’Carroll, Schwartz, Genet, and Ebbesen, Angew. Chem. Int. Ed.1433-785110.1002/anie.201006019 50, 2085 (2011)] have demonstrated that optical transmission through an array of subwavelength holes in a metal film can be enhanced by the intentional presence of dyes in the system. As the transmission maximum occurs spectrally close to the absorption resonances of the dyes, this phenomenon was christened “absorption induced transparency”. Here, a theoretical study on absorption induced transparency is presented. The results show that the appearance of transmission maxima requires that the absorbent fills the holes and that it occurs also for single holes. Furthermore, it is shown that the transmission process is nonresonant, being composed by a sequential passage of the electromagnetic field through the hole. Finally, the physical origin of the phenomenon is demonstrated to be nonplasmonic, which implies that absorption induced transparency should also occur at the infrared or terahertz frequency regimes.

  7. Atmospheric Absorption Parameters for Laser Propagation

    DTIC Science & Technology

    2007-11-02

    high-resolution, good photometric accuracy data for numerous bands in the 3-5 Am region, using the facility at Kitt Peak National Solar Observatory. The...L49-L52 (2001). 44. A. Castrillo, G. Gagliardi, G. Casa , and L. Gianfrani, "Combined interferometric and absorption-spectroscopic technique for...from FT visible solar absorption spectra and evaluation of spectroscopic databases," JQRST 82, 133-150 (2003). 53. D. Jacquemart, R.R. Gamache, and L.S

  8. Seasonal Solar Thermal Absorption Energy Storage Development.

    PubMed

    Daguenet-Frick, Xavier; Gantenbein, Paul; Rommel, Mathias; Fumey, Benjamin; Weber, Robert; Gooneseker, Kanishka; Williamson, Tommy

    2015-01-01

    This article describes a thermochemical seasonal storage with emphasis on the development of a reaction zone for an absorption/desorption unit. The heat and mass exchanges are modelled and the design of a suitable reaction zone is explained. A tube bundle concept is retained for the heat and mass exchangers and the units are manufactured and commissioned. Furthermore, experimental results of both absorption and desorption processes are presented and the exchanged power is compared to the results of the simulations.

  9. The economics of solar powered absorption cooling

    NASA Technical Reports Server (NTRS)

    Bartlett, J. C.

    1978-01-01

    Analytic procedure evaluates cost of combining absorption-cycle chiller with solar-energy system in residential or commercial application. Procedure assumes that solar-energy system already exists to heat building and that cooling system must be added. Decision is whether to cool building with conventional vapor-compression-cycle chiller or to use solar-energy system to provide heat input to absorption chiller.

  10. Ultraviolet absorption cross sections of hydrogen peroxide

    NASA Technical Reports Server (NTRS)

    Lin, C. L.; Rohatgi, N. K.; Demore, W. B.

    1978-01-01

    Absorption cross-sections of hydrogen peroxide vapor and of neutral aqueous solutions of hydrogen peroxide were measured in the wavelength range from 195 to 350 nm at 296 K. The spectrophotometric procedure is described, and the reported cross-sections are compared with values obtained by other researchers. Photodissociation coefficients of atmospheric H2O2 were calculated for direct absorption of unscattered solar radiation, and the vertical distributions of these coefficients are shown for various solar zenith angles.

  11. Vitamin D and intestinal calcium absorption.

    PubMed

    Christakos, Sylvia; Dhawan, Puneet; Porta, Angela; Mady, Leila J; Seth, Tanya

    2011-12-05

    The principal function of vitamin D in calcium homeostasis is to increase calcium absorption from the intestine. Calcium is absorbed by both an active transcellular pathway, which is energy dependent, and by a passive paracellular pathway through tight junctions. 1,25Dihydroxyvitamin D(3) (1,25(OH)(2)D(3)) the hormonally active form of vitamin D, through its genomic actions, is the major stimulator of active intestinal calcium absorption which involves calcium influx, translocation of calcium through the interior of the enterocyte and basolateral extrusion of calcium by the intestinal plasma membrane pump. This article reviews recent studies that have challenged the traditional model of vitamin D mediated transcellular calcium absorption and the crucial role of specific calcium transport proteins in intestinal calcium absorption. There is also increasing evidence that 1,25(OH)(2)D(3) can enhance paracellular calcium diffusion. The influence of estrogen, prolactin, glucocorticoids and aging on intestinal calcium absorption and the role of the distal intestine in vitamin D mediated intestinal calcium absorption are also discussed.

  12. A search for intervening HI absorption

    NASA Astrophysics Data System (ADS)

    Reeves, Sarah N.; Sadler, Elaine M.; Allison, James R.; Koribalski, Baerbel S.; Curran, Stephen J.

    2013-03-01

    HI absorption-line studies provide a unique probe of the gas distribution and kinematics in galaxies well beyond the local universe (z ≳ 0.3). HI absorption-line surveys with next-generation radio telescopes will provide the first large-scale studies of HI in a redshift regime which is poorly understood. However, we currently lack the understanding to infer galaxy properties from absorption-line observations alone. To address this issue, we are conducting a search for intervening HI absorption in a sample of 20 nearby galaxies. Our aim is to investigate how the detection rate varies with distance from the galaxy. We target sight-lines to bright continuum sources, which intercept known gas-rich galaxies, selected from the HIPASS Bright Galaxy Catalogue (Koribalski et al. 2004). In our pilot sample, six galaxies with impact parameters < 20 kpc, we do not detect any absorption lines - although all are detected in 21cm emission. This indicates that an absorption non-detection cannot simply be interpreted as an absence of neutral gas - see Fig. 1. Our detection rate is low compared to previous surveys e.g. Gupta et al. (2010). This is, at least partially, due to the high resolution of the observations reducing the flux of the background source, which will also be an issue in future surveys, such as ASKAP-FLASH.

  13. High temperature measurement of water vapor absorption

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

  14. Investigation of locally resonant absorption and factors affecting the absorption band of a phononic glass

    NASA Astrophysics Data System (ADS)

    Chen, Meng; Jiang, Heng; Feng, Yafei; Wang, Yuren

    2014-12-01

    We experimentally and theoretically investigated the mechanisms of acoustic absorption in phononic glass to optimize its properties. First, we experimentally studied its locally resonant absorption mechanism. From these results, we attributed its strong sound attenuation to its locally resonant units and its broadband absorption to its networked structure. These experiments also indicated that the porosity and thickness of the phononic glass must be tuned to achieve the best sound absorption at given frequencies. Then, using lumped-mass methods, we studied how the absorption bandgaps of the phononic glass were affected by various factors, including the porosity and the properties of the coating materials. These calculations gave optimal ranges for selecting the porosity, modulus of the coating material, and ratio of the compliant coating to the stiff matrix to achieve absorption bandgaps in the range of 6-30 kHz. This paper provides guidelines for designing phononic glasses with proper structures and component materials to work in specific frequency ranges.

  15. The Effect of Surface Heterogeneity on Cloud Absorption Estimates

    NASA Technical Reports Server (NTRS)

    Chiu, Jui-Yuan C.; Marshak, Alexander; Wiscombe, Warren J.

    2004-01-01

    This study presents a systematic and quantitative analysis of the effect of inhomogeneous surface albedo on shortwave cloud absorption estimates. We use 3D radiative transfer modeling with gradually complex clouds over a simplified surface to calculate cloud absorption. We find that averaging surface albedo always underestimates cloud absorption, and thus accounting for surface heterogeneity always enhances cloud absorption. However, the impact on cloud absorption estimates is not enough to explain the discrepancy between measured and model calculated shortwave cloud absorptions.

  16. Water-related absorption in fibrous diamonds

    NASA Astrophysics Data System (ADS)

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

    2003-04-01

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

  17. Polarization control of intermediate state absorption in resonance-mediated multi-photon absorption process

    NASA Astrophysics Data System (ADS)

    Xu, Shuwu; Huang, Yunxia; Yao, Yunhua; Jia, Tianqing; Ding, Jingxin; Zhang, Shian; Sun, Zhenrong

    2015-07-01

    We theoretically and experimentally demonstrate the control of the intermediate state absorption in an (n + m) resonance-mediated multi-photon absorption process by the polarization-modulated femtosecond laser pulse. An analytical solution of the intermediate state absorption in a resonance-mediated multi-photon absorption process is obtained based on the time-dependent perturbation theory. Our theoretical results show that the control efficiency of the intermediate state absorption by the polarization modulation is independent of the laser intensity when the transition from the intermediate state to the final state is coupled by the single-photon absorption, but will be affected by the laser intensity when this transition is coupled by the non-resonant multi-photon absorption. These theoretical results are experimentally confirmed via a two-photon fluorescence control in (2 + 1) resonance-mediated three-photon absorption of Coumarin 480 dye and a single-photon fluorescence control in (1 + 2) resonance-mediated three-photon absorption of IR 125 dye.

  18. Quantifying the Magnitude of Anomalous Solar Absorption

    SciTech Connect

    Ackerman, Thomas P.; Flynn, Donna M.; Marchand, Roger T.

    2003-05-16

    The data set from ARESE II, sponsored by the Atmospheric Radiation Measurement Program, provides a unique opportunity to understand solar absorption in the atmosphere because of the combination of three sets of broadband solar radiometers mounted on the Twin Otter aircraft and the ground based instruments at the ARM Southern Great Plains facility. In this study, we analyze the measurements taken on two clear sky days and three cloudy days and model the solar radiative transfer in each case with two different models. On the two clear days, the calculated and measured column absorptions agree to better than 10 Wm-2, which is about 10% of the total column absorption. Because both the model fluxes and the individual radiometer measurements are accurate to no better than 10 Wm-2, we conclude that the models and measurements are essentially in agreement. For the three cloudy days, the model calculations agree very well with each other and on two of the three days agree with the measurements to 20 Wm-2 or less out of a total column absorption of more than 200 Wm-2, which is again agreement at better than 10%. On the third day, the model and measurements agree to either 8% or 14% depending on which value of surface albedo is used. Differences exceeding 10% represent a significant absorption difference between model and observations. In addition to the uncertainty in absorption due to surface albedo, we show that including aerosol with an optical depth similar to that found on clear days can reduce the difference between model and measurement by 5% or more. Thus, we conclude that the ARESE II results are incompatible with previous studies reporting extreme anomalous absorption and can be modeled with our current understanding of radiative transfer.

  19. Absorption of cyclosporine A after oral dosing.

    PubMed

    Grevel, J

    1986-12-01

    Variability in the absorption of CsA seems to contribute to the observed lack of correlation between the size of the oral dose and the trough concentration at steady state. Absorption is probably improved by thorough dispersion of the oral solution of CsA in the drink the patient prefers. Evidence for GI metabolism of CsA has only been gathered in animal experiments. The importance of bile for absorption of CsA into the portal blood is established. The bioavailability of CsA does not seem to be determined by the metabolism during the first passage through the liver. Enterohepatic recycling is likely for CsA metabolites and unlikely for unchanged CsA. A pharmacokinetic model that assumes zero-order absorption of CsA describes human data better than a model with first-order absorption. According to the zero-order model, CsA is absorbed only in the upper part of the small intestine by a mechanism that operates under saturation. Two independent findings in transplantation patients support this model. First, it was shown that small doses of CsA produce disproportionally high blood concentrations, probably due to a better bioavailability. Second, accelerated transit times in the intestine (diarrhea) lead to unexpectedly low blood concentrations, probably due to poor bioavailability. Further factors have been identified that cause low absorption of CsA: liver dysfunction and external bile drainage after liver transplantation. The influence of food on the absorption of CsA is still not determined conclusively, but it seems that giving CsA together with a standard breakfast results in higher blood concentrations. The observed increase in the bioavailability of CsA with time after transplantation could be caused by the attempt to steadily lower the dose.

  20. UV laser long-path absorption spectroscopy

    NASA Technical Reports Server (NTRS)

    Dorn, Hans-Peter; Brauers, Theo; Neuroth, Rudolf

    1994-01-01

    Long path Differential Optical Absorption Spectroscopy (DOAS) using a picosecond UV laser as a light source was developed in our institute. Tropospheric OH radicals are measured by their rotational absorption lines around 308 nm. The spectra are obtained using a high resolution spectrograph. The detection system has been improved over the formerly used optomechanical scanning device by application of a photodiode array which increased the observed spectral range by a factor of 6 and which utilizes the light much more effectively leading to a considerable reduction of the measurement time. This technique provides direct measurements of OH because the signal is given by the product of the absorption coefficient and the OH concentration along the light path according to Lambert-Beers law. No calibration is needed. Since the integrated absorption coefficient is well known the accuracy of the measurement essentially depends on the extent to which the OH absorption pattern can be detected in the spectra. No interference by self generated OH radicals in the detection lightpath has been observed. The large bandwidth (greater than 0.15 nm) and the high spectral resolution (1.5 pm) allows absolute determination of interferences by other trace gas absorptions. The measurement error is directly accessible from the absorption-signal to baseline-noise ratio in the spectra. The applicability of the method strongly depends on visibility. Elevated concentrations of aerosols lead to considerable attenuation of the laser light which reduces the S/N-ratio. In the moderately polluted air of Julich, where we performed a number of OH measurement spectra. In addition absorption features of unidentified species were frequently detected. A quantitative deconvolution even of the known species is not easy to achieve and can leave residual structures in the spectra. Thus interferences usually increase the noise and deteriorate the OH detection sensitivity. Using diode arrays for sensitive

  1. Intestinal absorption of aluminium in renal failure.

    PubMed

    Drüeke, Tilman B

    2002-01-01

    The proportion of the daily ingested aluminium that is absorbed in the intestinal tract has remained a matter of debate for many years because no reliable method of measurement was available. Studies with earlier analytic techniques reported fractional absorption of aluminium from as little as 0.001% to as much as 27% of an oral dose. Measurement of (26)Al by high-energy accelerator mass spectrometry has permitted more accurate analyses. In normal young rats, 0.05-0.1% of ingested aluminium is absorbed in the intestine, of which roughly half goes to the skeleton within 2 h, whereas the remaining half is excreted in the urine, most of it within 48 h. Deposition in organs other than the skeleton appears to be negligible. In healthy human volunteers, the most recent estimates of fractional intestinal (26)Al absorption were also in the range of 0.06-0.1%. In both rats and humans, intestinal absorption of aluminium is subject to many systemic and local factors. The latter include various compounds with which aluminium is complexed in the gut lumen, and gastric acidity. The influence of food is controversial; however, absorption appears higher in the fasted than the post-prandial state. Luminal phosphate concentration decreases aluminium absorption, whereas citrate increases it. For theoretical reasons, silicates should prevent aluminium absorption, but experimental evidence has not supported this theory. Whether water hardness affects aluminium bioavailability remains a matter of debate. General conditions may also modify aluminium absorption and deposition in bone. Examples of these general factors include the uraemic syndrome, diabetes mellitus, secondary hyperparathyroidism, vitamin D status, Alzheimer's disease and Down's syndrome. Awareness of intestinal absorption of aluminium is particularly important, given that aluminium-based binders continue to be used in uraemic patients, despite the hazards of aluminium accumulation. The lessons we have learned about

  2. Experimental determination of terahertz atmospheric absorption parameters

    NASA Astrophysics Data System (ADS)

    Slocum, David M.; Goyette, Thomas M.; Giles, Robert H.; Nixon, William E.

    2015-05-01

    The terahertz frequency regime is often used as the `chemical fingerprint' region of the electromagnetic spectrum since many molecules exhibit a dense selection of rotational and vibrational transitions. Water is a major component of the atmosphere and since it has a large dipole moment the propagation of terahertz radiation will be dominated by atmospheric effects. This study will present the results of high-­-resolution broadband measurements of the terahertz atmospheric absorption and detail the technique for directly measuring the pressure broadening coefficients, absolute absorption coefficients, line positions, and continuum effects. Differences between these measured parameters and those tabulated in HITRAN will be discussed. Once the water vapor absorption was characterized, the same technique was used to measure the line parameters for methanol, a trace gas of interest within Earth's atmosphere. Methanol has a dense absorption spectrum in the terahertz frequency region and is an important molecule in fields such as environmental monitoring, security, and astrophysics. The data obtained in the present study will be of immediate use for the remote sensing community, as it is uncommon to measure this many independent parameters as well as to measure the absolute absorption of the transitions. Current models rely on tabulated databases of calculated values for the line parameters measured in this study. Differences between the measured data and those in the databases will be highlighted and discussed.

  3. OH measurement by laser light absorption

    NASA Technical Reports Server (NTRS)

    Perner, D.

    1986-01-01

    Since the first attempt to measure atmospheric hydroxyl radicals by optical absorption in 1975 (Perner et al., 1976) this method has been continuously developed further and its major obstacles and limitations are known today. The laser beam needs to be expanded in order to reduce the beam divergence. At the same time the energy density of the laser beam which produces OH via ozone photolysis is reduced to such an extent that the self-produced OH concentration ranges well below the atmospheric value. Atmospheric absorptions should be observed over a wide spectral range so that not only the OH radicals are properly identified by several rotational lines but their absorption can be corrected for interfering absorptions from other air constituents as SO2, CH2O, CS2, etc., which can be identified in a wide spectral range with more confidence. Air turbulence demands fast spectral scanning or probing on and off the absorption line. Energy requirements should be kept small in field operations. In the experiment frequency doubled dye laser pulses at 308 nm are produced. The picosecond light pulses are expected to show a smooth profile (light intensity against wavelength) which will be broadened to the required spectral width according to the uncertainty principle. The pump laser will be an optoacoustically modulated Nd:YAG laser.

  4. Zinc absorption in inflammatory bowel disease

    SciTech Connect

    Valberg, L.S.; Flanagan, P.R.; Kertesz, A.; Bondy, D.C.

    1986-07-01

    Zinc absorption was measured in 29 patients with inflammatory bowel disease and a wide spectrum of disease activity to determine its relationship to disease activity, general nutritional state, and zinc status. Patients with severe disease requiring either supplementary oral or parenteral nutrition were excluded. The mean 65ZnCl2 absorption, in the patients, determined using a 65Zn and 51Cr stool-counting test, 45 +/- 17% (SD), was significantly lower than the values, 54 +/- 16%, in 30 healthy controls, P less than 0.05. Low 65ZnCl2 absorption was related to undernutrition, but not to disease activity in the absence of undernutrition or to zinc status estimated by leukocyte zinc measurements. Mean plasma zinc or leukocyte zinc concentrations in patients did not differ significantly from controls, and only two patients with moderate disease had leukocyte zinc values below the 5th percentile of normal. In another group of nine patients with inflammatory bowel disease of mild-to-moderate severity and minimal nutritional impairment, 65Zn absorption from an extrinsically labeled turkey test meal was 31 +/- 10% compared to 33 +/- 7% in 17 healthy controls, P greater than 0.1. Thus, impairment in 65ZnCl2 absorption in the patients selected for this study was only evident in undernourished persons with moderate or severe disease activity, but biochemical evidence of zinc deficiency was uncommon, and clinical features of zinc depletion were not encountered.

  5. Absorption mode FTICR mass spectrometry imaging.

    PubMed

    Smith, Donald F; Kilgour, David P A; Konijnenburg, Marco; O'Connor, Peter B; Heeren, Ron M A

    2013-12-03

    Fourier transform ion cyclotron resonance mass spectrometry offers the highest mass resolving power for molecular imaging experiments. This high mass resolving power ensures that closely spaced peaks at the same nominal mass are resolved for proper image generation. Typically higher magnetic fields are used to increase mass resolving power. However, a gain in mass resolving power can also be realized by phase correction of the data for absorption mode display. In addition to mass resolving power, absorption mode offers higher mass accuracy and signal-to-noise ratio over the conventional magnitude mode. Here, we present the first use of absorption mode for Fourier transform ion cyclotron resonance mass spectrometry imaging. The Autophaser algorithm is used to phase correct each spectrum (pixel) in the image, and then, these parameters are used by the Chameleon work-flow based data processing software to generate absorption mode "Datacubes" for image and spectral viewing. Absorption mode reveals new mass and spatial features that are not resolved in magnitude mode and results in improved selected ion image contrast.

  6. Biotin absorption by distal rat intestine

    SciTech Connect

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

    1987-12-01

    We used the in vivo intestinal loop approach, with short (10-min) and long (3-h) incubations, to examine biotin absorption in proximal jejunum, distal ileum, cecum and proximal colon. In short-term studies, luminal biotin disappearance from rat ileum was about half that observed in the jejunum, whereas absorption by proximal colon was about 12% of that in the jejunum. In 3-h closed-loop studies, the absorption of 1.0 microM biotin varied regionally. Biotin absorption was nearly complete in the small intestine after 3 h; however, only about 15% of the dose had been absorbed in the cecum and 27% in the proximal colon after 3 h. Independent of site of administration, the major fraction of absorbed biotin was recovered in the liver; measurable amounts of radioactive biotin were also present in kidney and plasma. The results support the potential nutritional significance for the rat of biotin synthesized by bacteria in the distal intestine, by demonstrating directly an absorptive capability of mammalian large bowel for this vitamin.

  7. Methane overtone absorption by intracavity laser spectroscopy

    NASA Technical Reports Server (NTRS)

    Obrien, James J.

    1990-01-01

    Interpretation of planetary methane (CH4) visible-near IR spectra, used to develop models of planetary atmospheres, has been hampered by a lack of suitable laboratory spectroscopic data. The particular CH4 spectral bands are due to intrinsically weak, high overtone-combination transitions too complex for classical spectroscopic analysis. The traditional multipass cell approach to measuring spectra of weakly absorbing species is insufficiently sensitive to yield reliable results for some of the weakest CH4 absorption features and is difficult to apply at the temperatures of the planetary environments. A time modulated form of intracavity laser spectroscopy (ILS), has been shown to provide effective absorption pathlengths of 100 to 200 km with sample cells less than 1 m long. The optical physics governing this technique and the experimental parameters important for obtaining reliable, quantitative results are now well understood. Quantitative data for CH4 absorption obtained by ILS have been reported recently. Illustrative ILS data for CH4 absorption in the 619.7 nm and 681.9 nm bands are presented. New ILS facilities at UM-St. Louis will be used to measure CH4 absorption in the 700 to 1000 nm region under conditions appropriate to the planetary atmospheres.

  8. Aerosol Angstrom Absorption Coefficient Comparisons during MILAGRO.

    NASA Astrophysics Data System (ADS)

    Marley, N. A.; Marchany-Rivera, A.; Kelley, K. L.; Mangu, A.; Gaffney, J. S.

    2007-12-01

    Measurements of aerosol absorption were obtained as part of the MAX-Mex component of the MILAGRO field campaign at site T0 (Instituto Mexicano de Petroleo in Mexico City) by using a 7-channel aethalometer (Thermo- Anderson) during the month of March, 2006. The absorption measurements obtained in the field at 370, 470, 520, 590, 660, 880, and 950 nm were used to determine the aerosol Angstrom absorption exponents by linear regression. Since, unlike other absorbing aerosol species (e.g. humic like substances, nitrated PAHs), black carbon absorption is relatively constant from the ultraviolet to the infrared with an Angstrom absorption exponent of -1 (1), a comparison of the Angstrom exponents can indicate the presence of aerosol components with an enhanced UV absorption over that expected from BC content alone. The Angstrom exponents determined from the aerosol absorption measurements obtained in the field varied from - 0.7 to - 1.3 during the study and was generally lower in the afternoon than the morning hours, indicating an increase in secondary aerosol formation and photochemically generated UV absorbing species in the afternoon. Twelve-hour integrated samples of fine atmospheric aerosols (<0.1micron) were also collected at site T0 and T1 (Universidad Technologica de Tecamac, State of Mexico) from 5 am to 5 pm (day) and from 5 pm to 5 am (night) during the month of March 2006. Samples were collected on quartz fiber filters with high volume impactor samplers. Continuous absorption spectra of these aerosol samples have been obtained in the laboratory from 280 to 900nm with the use of an integrating sphere coupled to a UV spectrometer (Beckman DU with a Labsphere accessory). The integrating sphere allows the detector to collect and spatially integrate the total radiant flux reflected from the sample and therefore allows for the measurement of absorption on highly reflective or diffusely scattering samples. These continuous spectra have also been used to obtain the

  9. Broadband absorption engineering of hyperbolic metafilm patterns

    NASA Astrophysics Data System (ADS)

    Ji, Dengxin; Song, Haomin; Zeng, Xie; Hu, Haifeng; Liu, Kai; Zhang, Nan; Gan, Qiaoqiang

    2014-03-01

    Perfect absorbers are important optical/thermal components required by a variety of applications, including photon/thermal-harvesting, thermal energy recycling, and vacuum heat liberation. While there is great interest in achieving highly absorptive materials exhibiting large broadband absorption using optically thick, micro-structured materials, it is still challenging to realize ultra-compact subwavelength absorber for on-chip optical/thermal energy applications. Here we report the experimental realization of an on-chip broadband super absorber structure based on hyperbolic metamaterial waveguide taper array with strong and tunable absorption profile from near-infrared to mid-infrared spectral region. The ability to efficiently produce broadband, highly confined and localized optical fields on a chip is expected to create new regimes of optical/thermal physics, which holds promise for impacting a broad range of energy technologies ranging from photovoltaics, to thin-film thermal absorbers/emitters, to optical-chemical energy harvesting.

  10. Metamaterial with electromagnetic transparency under multiband absorptions

    NASA Astrophysics Data System (ADS)

    Zhang, Xu; Qi, Limei

    2017-02-01

    We propose a metal-dielectric-metal (MDM) metamaterial that has an electromagnetic (EM) transparency spectrum under multiband absorptions in the C and the X bands. The ground continuous metal film used in the conventional metamaterial absorber (MA) is replaced by a structured ground plane (SGP) in our design. The band-pass properties of the front patterned metal film and the SGP determine the EM transparency spectrum, while the magnetic and the electric resonances in the MDM structure contribute to the multiband absorptions. Due to the symmetric structure of the unit cell, the absorption bands and the EM transparency spectrum of the metamaterial have the property of polarization independency. Despite the normal incidence, the metamaterial can also be used for non-normal incidence.

  11. Nanofibrous membrane-based absorption refrigeration system

    SciTech Connect

    Isfahani, RN; Sampath, K; Moghaddam, S

    2013-12-01

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

  12. Plasmon absorption modulator systems and methods

    DOEpatents

    Kekatpure, Rohan Deodatta; Davids, Paul

    2014-07-15

    Plasmon absorption modulator systems and methods are disclosed. A plasmon absorption modulator system includes a semiconductor substrate, a plurality of quantum well layers stacked on a top surface of the semiconductor substrate, and a metal layer formed on a top surface of the stack of quantum well layers. A method for modulating plasmonic current includes enabling propagation of the plasmonic current along a metal layer, and applying a voltage across the stack of quantum well layers to cause absorption of a portion of energy of the plasmonic current by the stack of quantum well layers. A metamaterial switching system includes a semiconductor substrate, a plurality of quantum well layers stacked on a top surface of the semiconductor substrate, and at least one metamaterial structure formed on a top surface of the stack of quantum well layers.

  13. Laser absorption phenomena in flowing gas devices

    NASA Technical Reports Server (NTRS)

    Chapman, P. K.; Otis, J. H.

    1976-01-01

    A theoretical and experimental investigation is presented of inverse Bremsstrahlung absorption of CW CO2 laser radiation in flowing gases seeded with alkali metals. In order to motivate this development, some simple models are described of several space missions which could use laser powered rocket vehicles. Design considerations are given for a test call to be used with a welding laser, using a diamond window for admission of laser radiation at power levels in excess of 10 kW. A detailed analysis of absorption conditions in the test cell is included. The experimental apparatus and test setup are described and the results of experiments presented. Injection of alkali seedant and steady state absorption of the laser radiation were successfully demonstrated, but problems with the durability of the diamond windows at higher powers prevented operation of the test cell as an effective laser powered thruster.

  14. Rotational averaging of multiphoton absorption cross sections

    NASA Astrophysics Data System (ADS)

    Friese, Daniel H.; Beerepoot, Maarten T. P.; Ruud, Kenneth

    2014-11-01

    Rotational averaging of tensors is a crucial step in the calculation of molecular properties in isotropic media. We present a scheme for the rotational averaging of multiphoton absorption cross sections. We extend existing literature on rotational averaging to even-rank tensors of arbitrary order and derive equations that require only the number of photons as input. In particular, we derive the first explicit expressions for the rotational average of five-, six-, and seven-photon absorption cross sections. This work is one of the required steps in making the calculation of these higher-order absorption properties possible. The results can be applied to any even-rank tensor provided linearly polarized light is used.

  15. Rotational averaging of multiphoton absorption cross sections.

    PubMed

    Friese, Daniel H; Beerepoot, Maarten T P; Ruud, Kenneth

    2014-11-28

    Rotational averaging of tensors is a crucial step in the calculation of molecular properties in isotropic media. We present a scheme for the rotational averaging of multiphoton absorption cross sections. We extend existing literature on rotational averaging to even-rank tensors of arbitrary order and derive equations that require only the number of photons as input. In particular, we derive the first explicit expressions for the rotational average of five-, six-, and seven-photon absorption cross sections. This work is one of the required steps in making the calculation of these higher-order absorption properties possible. The results can be applied to any even-rank tensor provided linearly polarized light is used.

  16. Super-Resonant Intracavity Coherent Absorption

    NASA Astrophysics Data System (ADS)

    Malara, P.; Campanella, C. E.; Giorgini, A.; Avino, S.; de Natale, P.; Gagliardi, G.

    2016-07-01

    The capability of optical resonators to extend the effective radiation-matter interaction length originates from a multipass effect, hence is intrinsically limited by the resonator’s quality factor. Here, we show that this constraint can be overcome by combining the concepts of resonant interaction and coherent perfect absorption (CPA). We demonstrate and investigate super-resonant coherent absorption in a coupled Fabry-Perot (FP)/ring cavity structure. At the FP resonant wavelengths, the described phenomenon gives rise to split modes with a nearly-transparent peak and a peak whose transmission is exceptionally sensitive to the intracavity loss. For small losses, the effective interaction pathlength of these modes is proportional respectively to the ratio and the product of the individual finesse coefficients of the two resonators. The results presented extend the conventional definition of resonant absorption and point to a way of circumventing the technological limitations of ultrahigh-quality resonators in spectroscopy and optical sensing schemes.

  17. Estimation of molar absorptivities and pigment sizes for eumelanin and pheomelanin using femtosecond transient absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Piletic, Ivan R.; Matthews, Thomas E.; Warren, Warren S.

    2009-11-01

    Fundamental optical and structural properties of melanins are not well understood due to their poor solubility characteristics and the chemical disorder present during biomolecular synthesis. We apply nonlinear transient absorption spectroscopy to quantify molar absorptivities for eumelanin and pheomelanin and thereby get an estimate for their average pigment sizes. We determine that pheomelanin exhibits a larger molar absorptivity at near IR wavelengths (750nm), which may be extended to shorter wavelengths. Using the molar absorptivities, we estimate that melanin pigments contain ˜46 and 28 monomer units for eumelanin and pheomelanin, respectively. This is considerably larger than the oligomeric species that have been recently proposed to account for the absorption spectrum of eumelanin and illustrates that larger pigments comprise a significant fraction of the pigment distribution.

  18. Estimation of molar absorptivities and pigment sizes for eumelanin and pheomelanin using femtosecond transient absorption spectroscopy.

    PubMed

    Piletic, Ivan R; Matthews, Thomas E; Warren, Warren S

    2009-11-14

    Fundamental optical and structural properties of melanins are not well understood due to their poor solubility characteristics and the chemical disorder present during biomolecular synthesis. We apply nonlinear transient absorption spectroscopy to quantify molar absorptivities for eumelanin and pheomelanin and thereby get an estimate for their average pigment sizes. We determine that pheomelanin exhibits a larger molar absorptivity at near IR wavelengths (750 nm), which may be extended to shorter wavelengths. Using the molar absorptivities, we estimate that melanin pigments contain approximately 46 and 28 monomer units for eumelanin and pheomelanin, respectively. This is considerably larger than the oligomeric species that have been recently proposed to account for the absorption spectrum of eumelanin and illustrates that larger pigments comprise a significant fraction of the pigment distribution.

  19. Absorption of acoustic waves by sunspots. II - Resonance absorption in axisymmetric fibril models

    NASA Technical Reports Server (NTRS)

    Rosenthal, C. S.

    1992-01-01

    Analytical calculations of acoustic waves scattered by sunspots which concentrate on the absorption at the magnetohydrodynamic Alfven resonance are extended to the case of a flux-tube embedded in a uniform atmosphere. The model is based on a flux-tubes of varying radius that are highly structured, translationally invariant, and axisymmetric. The absorbed fractional energy is determined for different flux-densities and subphotospheric locations with attention given to the effects of twist. When the flux is highly concentrated into annuli efficient absorption is possible even when the mean magnetic flux density is low. The model demonstrates low absorption at low azimuthal orders even in the presence of twist which generally increases the range of wave numbers over which efficient absorption can occur. Resonance absorption is concluded to be an efficient mechanism in monolithic sunspots, fibril sunspots, and plage fields.

  20. Enhanced absorption cycle computer model. Final report

    SciTech Connect

    Grossman, G.; Wilk, M.

    1993-09-01

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

  1. Cloud geometry effects on atmospheric solar absorption

    SciTech Connect

    Fu, Q.; Cribb, M.C.; Barker, H.W.; Krueger, S.K.; Grossman, A.

    2000-04-15

    A 3D broadband solar radiative transfer scheme is formulated by integrating a Monte Carlo photon transport algorithm with the Fu-Liou radiation model. It is applied to fields of tropical mesoscale convective clouds and subtropical marine boundary layer clouds that were generated by a 2D cloud-resolving model. The effects of cloud geometry on the radiative energy budget are examined by comparing the full-resolution Monte Carlo results with those from the independent column approximation (ICA) that applies the plane-parallel radiation model to each column. For the tropical convective cloud system, it is found that cloud geometry effects always enhance atmospheric solar absorption regardless of solar zenith angle. In a large horizontal domain (512 km), differences in domain-averaged atmospheric absorption between the Monte Carlo and the ICA are less than 4 W m{sup {minus}2} in the daytime. However, for a smaller domain (e.g., 75 km) containing a cluster of deep convective towers, domain-averaged absorption can be enhanced by more than 20 W m{sup {minus}2}. For a subtropical marine boundary layer cloud system during the stratus-to-cumulus transition, calculations show that the ICA works very well for domain-averaged fluxes of the stratocumulus cloud fields even for a very small domain (4.8 km). For the trade cumulus cloud field, the effects of cloud sides and horizontal transport of photons become more significant. Calculations have also been made for both cloud systems including black carbon aerosol and a water vapor continuum. It is found that cloud geometry produces no discernible effects on the absorption enhancement due to the black carbon aerosol and water vapor continuum. The current study indicates that the atmospheric absorption enhancement due to cloud-related 3D photon transport is small. This enhancement could not explain the excess absorption suggested by recent studies.

  2. Potassium emission absorption system. Topical report 12

    SciTech Connect

    Bauman, L.E.

    1995-04-01

    The Potassium Emission Absorption System is one of the advanced optical diagnostics developed at Mississippi State University to provide support for the demonstration of prototype-scale coal-fired combustion magnetohydrodynamic (MHD) electrical power generation. Intended for application in the upstream of an MHD flow, the system directly measures gas temperature and neutral potassium atom number density through spectroscopic emission absorption techniques. From these measurements the electron density can be inferred from a statistical equilibrium calculation and the electron conductivity in the MHD channel found by use of an electron mobility model. The instrument has been utilized for field test measurements on MHD facilities for almost a decade and has been proven to provide useful measurements as designed for MHD nozzle, channel, and diffuser test sections. The theory of the measurements, a system description, its capabilities, and field test measurement results are reported here. During the development and application of the instrument several technical issues arose which when addressed advanced the state of the art in emission absorption measurement. Studies of these issues are also reported here and include: two-wavelength measurements for particle-laden flows, potassium D-line far wing absorption coefficient, bias in emission absorption measurements arising from dirty windows and misalignments, non-coincident multiwavelength emission absorption sampling errors, and lineshape fitting for boundary layer flow profile information. Although developed for NLHD application, the instrument could be applied to any high temperature flow with a resonance line in the 300 to 800 nm range, for instance other types of flames, rocket plumes or low temperature plasmas.

  3. Intestinal Lipid Absorption and Lipoprotein Formation

    PubMed Central

    Hussain, M. Mahmood

    2014-01-01

    Purpose of review The purpose of this review is to summarize evidence for the presence of two pathways of lipid absorption and their regulation. Recent findings Lipid absorption involves hydrolysis of dietary fat in the lumen of the intestine followed by the uptake of hydrolyzed products by enterocytes. Lipids are re-synthesized in the endoplasmic reticulum and are either secreted with chylomicrons and high density lipoproteins or stored as cytoplasmic lipid droplets. Lipids in the droplets are hydrolyzed and are secreted at a later time. Secretion of lipids by the chylomicron and HDL pathways are critically dependent on MTP and ABCA1, respectively, and are regulated independently. Gene ablation studies showed that MTP function and chylomicron assembly is essential for the absorption of triglyceride and retinyl esters. Ablation of MTP abolishes triglyceride absorption and results in massive triglyceride accumulation in enterocytes. Although majority of phospholipid, cholesterol and vitamin E are absorbed through the chylomicron pathway, a significant amount of these lipids are also absorbed via the HDL pathway. Chylomicron assembly and secretion is increased by the enhanced availability of fatty acids, whereas HDL pathway is upregulated by LXR agonists. Intestinal insulin resistance increases chylomicron and might reduce HDL production. Summary Triglycerides are exclusively transported via the chylomicron pathway and this process is critically dependent on MTP. Besides chylomicrons, absorption of phospholipids, free cholesterol, retinol, and vitamin E also involves high density lipoproteins. These two pathways are complementary and are regulated independently. They may be targeted to lower lipid absorption in order to control hyperlipidemia, obesity, metabolic syndrome, steatosis, insulin resistance, atherosclerosis and other disorders. PMID:24751933

  4. Triplet absorption spectroscopy and electromagnetically induced transparency

    NASA Astrophysics Data System (ADS)

    Ghafoor, F.; Nazmitdinov, R. G.

    2016-09-01

    Coherence phenomena in a four-level atomic system, cyclically driven by three coherent fields, are investigated thoroughly at zero and weak magnetic fields. Each strongly interacting atomic state is converted to a triplet due to a dynamical Stark effect. Two dark lines with a Fano-like profile arise in the triplet absorption spectrum with anomalous dispersions. We provide conditions to control the widths of the transparency windows by means of the relative phase of the driving fields and the intensity of the microwave field, which closes the optical system loop. The effect of Doppler broadening on the results of the triplet absorption spectroscopy is analysed in detail.

  5. Subbarrier absorption in a stationary superlattice

    NASA Technical Reports Server (NTRS)

    Arutyunyan, G. M.; Nerkararyan, K. V.

    1984-01-01

    The calculation of the interband absorption coefficient was carried out in the classical case, when the frequency of light was assumed to bind two miniband subbarrier states of different bands. The influence of two dimensional Mott excitons on this absorption was studied and a comparison was made with the experiment. All of these considerations were done taking into account the photon wave vector (the phase spatial heterogeneity). The basic traits of the energy spectra of superlattice semiconductors, their kinetic and optical properties, and possible means of electromagnetic wave intensification were examined. By the density matrix method, a theory of electrical and electromagnetic properties of superlattices was suggested.

  6. Universal Parameterization of Absorption Cross Sections

    NASA Technical Reports Server (NTRS)

    Tripathi, R. K.; Cucinotta, Francis A.; Wilson, John W.

    1999-01-01

    Our prior nuclear absorption cross sections model is extended for light systems (A less than or equal to 4) where either both projectile and target are light particles or one is a light particle and the other is a medium or heavy nucleus. The agreement with experiment is excellent for these cases as well. Present work in combination with our original model provides a comprehensive picture of absorption cross sections for light, medium, and heavy systems, a very valuable input for radiation protection studies.

  7. Percutaneous absorption with emphasis on sunscreens.

    PubMed

    Gonzalez, Helena

    2010-04-01

    Sunscreens are widely used products. When recreationally used they are applied to large areas of the skin repeatedly. In moisturizers and foundation it is common to find sun protective ingredients, in these cases the product is usually applied to smaller areas but often done daily. Active ingredients in sunscreens can be absorbed by the skin. Percutaneous absorption is an important factor to take into consideration. There are several methods to measure the percutaneous absorption, both in vivo and/or in vitro. This paper will give an overview of the different methods.

  8. Absorption of iron from ferric hydroxypyranone complexes.

    PubMed

    Maxton, D G; Thompson, R P; Hider, R C

    1994-02-01

    The absorption of 59Fe from preparations of FeSO4 and the ferric hydroxypyranone complexes maltol and ethyl maltol was studied by whole-body counting in normal subjects and patients with Fe deficiency. Fe in the Fe3+ complexes was in general absorbed almost as well as Fe2+. It is concluded that the absorption of Fe3+ from hydroxypyranone complexes is much greater than that from simple Fe3+ salts; this may prove an efficient and less toxic form of Fe for the treatment of deficiency.

  9. Dietary Phospholipids and Intestinal Cholesterol Absorption

    PubMed Central

    Cohn, Jeffrey S.; Kamili, Alvin; Wat, Elaine; Chung, Rosanna W. S.; Tandy, Sally

    2010-01-01

    Experiments carried out with cultured cells and in experimental animals have consistently shown that phospholipids (PLs) can inhibit intestinal cholesterol absorption. Limited evidence from clinical studies suggests that dietary PL supplementation has a similar effect in man. A number of biological mechanisms have been proposed in order to explain how PL in the gut lumen is able to affect cholesterol uptake by the gut mucosa. Further research is however required to establish whether the ability of PLs to inhibit cholesterol absorption is of therapeutic benefit. PMID:22254012

  10. Laser isotope separation by multiple photon absorption

    DOEpatents

    Robinson, C.P.; Rockwood, S.D.; Jensen, R.J.; Lyman, J.L.; Aldridge, J.P. III.

    1987-04-07

    Multiple photon absorption from an intense beam of infrared laser light may be used to induce selective chemical reactions in molecular species which result in isotope separation or enrichment. The molecular species must have a sufficient density of vibrational states in its vibrational manifold that, is the presence of sufficiently intense infrared laser light tuned to selectively excite only those molecules containing a particular isotope, multiple photon absorption can occur. By this technique, for example, intense CO[sub 2] laser light may be used to highly enrich [sup 34]S in natural SF[sub 6] and [sup 11]B in natural BCl[sub 3]. 8 figs.

  11. Laser isotope separation by multiple photon absorption

    DOEpatents

    Robinson, C. Paul; Rockwood, Stephen D.; Jensen, Reed J.; Lyman, John L.; Aldridge, III, Jack P.

    1987-01-01

    Multiple photon absorption from an intense beam of infrared laser light may be used to induce selective chemical reactions in molecular species which result in isotope separation or enrichment. The molecular species must have a sufficient density of vibrational states in its vibrational manifold that, is the presence of sufficiently intense infrared laser light tuned to selectively excite only those molecules containing a particular isotope, multiple photon absorption can occur. By this technique, for example, intense CO.sub.2 laser light may be used to highly enrich .sup.34 S in natural SF.sub.6 and .sup.11 B in natural BCl.sub.3.

  12. Laser isotope separation by multiple photon absorption

    DOEpatents

    Robinson, C. Paul; Rockwood, Stephen D.; Jensen, Reed J.; Lyman, John L.; Aldridge, III, Jack P.

    1977-01-01

    Multiple photon absorption from an intense beam of infrared laser light may be used to induce selective chemical reactions in molecular species which result in isotope separation or enrichment. The molecular species must have a sufficient density of vibrational states in its vibrational manifold that, in the presence of sufficiently intense infrared laser light tuned to selectively excite only those molecules containing a particular isotope, multiple photon absorption can occur. By this technique, for example, intense CO.sub.2 laser light may be used to highly enrich .sup.34 S in natural SF.sub.6 and .sup.11 B in natural BCl.sub.3.

  13. XUV Absorption by Solid Density Aluminum

    SciTech Connect

    Iglesias, C A

    2009-09-21

    An inverse bremsstrahlung model for plasmas and simple metals that approximates the cold, solid Al experimental data below the L-edge is applied to matter conditions relevant to XUV laser applications. The model involves an all-order calculation using a semi-analytical effective electron-ion interaction. The predicted increases in XUV absorption with rising temperature occur via two effects: increased availability of final states from reduced electron degeneracy and a stronger electron-ion interaction from reduced screening. Discrepancies in the temperature dependence as well as other details between the present approach and a recently proposed absorption model are discussed.

  14. Thin structured rigid body for acoustic absorption

    NASA Astrophysics Data System (ADS)

    Starkey, T. A.; Smith, J. D.; Hibbins, A. P.; Sambles, J. R.; Rance, H. J.

    2017-01-01

    We present a thin acoustic metamaterial absorber, comprised of only rigid metal and air, that gives rise to near unity absorption of airborne sound on resonance. This simple, easily fabricated, robust structure comprising a perforated metal plate separated from a rigid wall by a deeply subwavelength channel of air is an ideal candidate for a sound absorbing panel. The strong absorption in the system is attributed to the thermo-viscous losses arising from a sound wave guided between the plate and the wall, defining the subwavelength channel.

  15. Sodium Absorption by Intact Sugar Beet Plants

    PubMed Central

    El-Sheikh, Adel M; Ulrich, Albert

    1971-01-01

    Sodium absorption by intact sugar beet plants (Beta vulgaris) was found to be mediated by at least two distinct mechanisms when uptake was studied over a wide range of Na and K concentrations. The first mechanism operates at low Na concentrations (<1 milliequivalent per liter); presence of K completely blocks this mechanism for Na. The second mechanism operates at high Na concentrations (>1 milliequivalent per liter), transporting Na as well as K; but apparently this mechanism is not active for Na absorption in young sugar beet plants up to the 10-leaf stage. PMID:16657872

  16. New Parameterization of Neutron Absorption Cross Sections

    NASA Astrophysics Data System (ADS)

    Tripathi, Ram K.; Wilson, John W.; Cucinotta, Francis A.

    1997-06-01

    Recent parameterization of absorption cross sections for any system of charged ion collisions, including proton-nucleus collisions, is extended for neutron-nucleus collisions valid from approx. 1 MeV to a few GeV, thus providing a comprehensive picture of absorption cross sections for any system of collision pairs (charged or uncharged). The parameters are associated with the physics of the problem. At lower energies, optical potential at the surface is important, and the Pauli operator plays an increasingly important role at intermediate energies. The agreement between the calculated and experimental data is better than earlier published results.

  17. New Parameterization of Neutron Absorption Cross Sections

    NASA Technical Reports Server (NTRS)

    Tripathi, Ram K.; Wilson, John W.; Cucinotta, Francis A.

    1997-01-01

    Recent parameterization of absorption cross sections for any system of charged ion collisions, including proton-nucleus collisions, is extended for neutron-nucleus collisions valid from approx. 1 MeV to a few GeV, thus providing a comprehensive picture of absorption cross sections for any system of collision pairs (charged or uncharged). The parameters are associated with the physics of the problem. At lower energies, optical potential at the surface is important, and the Pauli operator plays an increasingly important role at intermediate energies. The agreement between the calculated and experimental data is better than earlier published results.

  18. Monitoring of MOCVD reactants by UV absorption

    SciTech Connect

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

    1995-07-01

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

  19. High-Absorption-Efficiency Superlattice Solar Cells by Excitons

    NASA Astrophysics Data System (ADS)

    Nishinaga, Jiro; Kawaharazuka, Atsushi; Onomitsu, Koji; Horikoshi, Yoshiji

    2013-11-01

    The effect of excitonic absorption on solar cell efficiency has been investigated using solar cells with AlGaAs/GaAs superlattice structures. Numerical calculations reveal that excitonic absorption considerably enhances the overall absorption of bulk GaAs. Excitonic absorption shows strong and sharp peaks at the absorption edge and in the energy region above the band gap. Absorption enhancement is also achieved in the AlGaAs/GaAs superlattice. The measured quantum efficiency spectra of the superlattice solar cells are quite similar to the calculated absorption spectra considering the excitonic effect. The superlattice solar cells are confirmed to have high absorption coefficient compared with the GaAs and AlGaAs bulk solar cells. These results suggest that the enhanced absorption by excitons can increase the quantum efficiency of solar cells. This effect is more prominent for the solar cells with small absorption layer thicknesses.

  20. Dissociative absorption: An empirically unique, clinically relevant, dissociative factor.

    PubMed

    Soffer-Dudek, Nirit; Lassri, Dana; Soffer-Dudek, Nir; Shahar, Golan

    2015-11-01

    Research of dissociative absorption has raised two questions: (a) Is absorption a unique dissociative factor within a three-factor structure, or a part of one general dissociative factor? Even when three factors are found, the specificity of the absorption factor is questionable. (b) Is absorption implicated in psychopathology? Although commonly viewed as "non-clinical" dissociation, absorption was recently hypothesized to be specifically associated with obsessive-compulsive symptoms. To address these questions, we conducted exploratory and confirmatory factor analyses on 679 undergraduates. Analyses supported the three-factor model, and a "purified" absorption scale was extracted from the original inclusive absorption factor. The purified scale predicted several psychopathology scales. As hypothesized, absorption was a stronger predictor of obsessive-compulsive symptoms than of general psychopathology. In addition, absorption was the only dissociative scale that longitudinally predicted obsessive-compulsive symptoms. We conclude that absorption is a unique and clinically relevant dissociative tendency that is particularly meaningful to obsessive-compulsive symptoms.

  1. Microwave absorption measurements of melting spherical and nonspherical hydrometeors

    NASA Technical Reports Server (NTRS)

    Hansman, R. J., Jr.

    1986-01-01

    Measurements were made of the absorption behavior of melting and freezing hydrometeors using resonant cavity perturbation techniques at a wavelength of 2.82 cm. Melting ice spheres with equivalent melted diameters between 1.15 and 2.00 mm exhibit a period of strong absorption during melting as predicted by prior theoretical calculations. However, the measured magnitude of the absorption peak exceeds the predicted value. Absorption measuremets of melting oblate and prolate ice ellipsoids also exhibit enhanced absorption during melting.

  2. Examination of the Measurement of Absorption Using the Reverberant Room Method for Highly Absorptive Acoustic Foam

    NASA Technical Reports Server (NTRS)

    Hughes, William O.; McNelis, Anne M.; Chris Nottoli; Eric Wolfram

    2015-01-01

    The absorption coefficient for material specimens are needed to quantify the expected acoustic performance of that material in its actual usage and environment. The ASTM C423-09a standard, "Standard Test Method for Sound Absorption and Sound Absorption Coefficients by the Reverberant Room Method" is often used to measure the absorption coefficient of material test specimens. This method has its basics in the Sabine formula. Although widely used, the interpretation of these measurements are a topic of interest. For example, in certain cases the measured Sabine absorption coefficients are greater than 1.0 for highly absorptive materials. This is often attributed to the diffraction edge effect phenomenon. An investigative test program to measure the absorption properties of highly absorbent melamine foam has been performed at the Riverbank Acoustical Laboratories. This paper will present and discuss the test results relating to the effect of the test materials' surface area, thickness and edge sealing conditions. A follow-on paper is envisioned that will present and discuss the results relating to the spacing between multiple piece specimens, and the mounting condition of the test specimen.

  3. Mathematical model of zinc absorption: effects of dietary calcium, protein and iron on zinc absorption.

    PubMed

    Miller, Leland V; Krebs, Nancy F; Hambidge, K Michael

    2013-02-28

    A previously described mathematical model of Zn absorption as a function of total daily dietary Zn and phytate was fitted to data from studies in which dietary Ca, Fe and protein were also measured. An analysis of regression residuals indicated statistically significant positive relationships between the residuals and Ca, Fe and protein, suggesting that the presence of any of these dietary components enhances Zn absorption. Based on the hypotheses that (1) Ca and Fe both promote Zn absorption by binding with phytate and thereby making it unavailable for binding Zn and (2) protein enhances the availability of Zn for transporter binding, the model was modified to incorporate these effects. The new model of Zn absorption as a function of dietary Zn, phytate, Ca, Fe and protein was then fitted to the data. The proportion of variation in absorbed Zn explained by the new model was 0·88, an increase from 0·82 with the original model. A reduced version of the model without Fe produced an equally good fit to the data and an improved value for the model selection criterion, demonstrating that when dietary Ca and protein are controlled for, there is no evidence that dietary Fe influences Zn absorption. Regression residuals and testing with additional data supported the validity of the new model. It was concluded that dietary Ca and protein modestly enhanced Zn absorption and Fe had no statistically discernable effect. Furthermore, the model provides a meaningful foundation for efforts to model nutrient interactions in mineral absorption.

  4. Nasal Absorption of Macromolecules from Powder Formulations and Effects of Sodium Carboxymethyl Cellulose on Their Absorption

    PubMed Central

    Tanaka, Akiko; Furubayashi, Tomoyuki; Matsushita, Akifumi; Inoue, Daisuke; Kimura, Shunsuke; Katsumi, Hidemasa; Sakane, Toshiyasu; Yamamoto, Akira

    2016-01-01

    The nasal absorption of macromolecules from powder formulations and the effect of sodium carboxymethyl cellulose (CMC-Na) as a pharmaceutical excipient on their absorption were studied. Model macromolecules were fluorescein isothiocyanate-labeled dextran (average molecular weight of 4.4kDa, FD4) and insulin. The plasma concentration of FD4 after application of the powder containing 50% starch (control) was higher than that after application of the solution, and the absorption from 50% starch powder was enhanced by the substitution of starch with CMC-Na. The fractional absorption of FD4 after administration of the CMC-Na powder formulation was 30% and 40% higher than that after administration from the solution and the starch powder, respectively. The nasal absorption of insulin from the powder and the effect of CMC-Na were similar with those of FD4. The effective absorption of FD4 and insulin after application of powder with CMC-Na could be due to the increase in the nasal residence of FD4 and insulin. No damage in the nasal mucosa or dysfunction of the mucociliary clearance was observed after application of the drug powder and CMC-Na. The present findings indicate that nasal delivery of powder formulations with the addition of CMC-Na as an excipient is a promising approach for improving the nasal absorption of macromolecules. PMID:27598527

  5. Fluoride absorption: independence from plasma fluoride levels

    SciTech Connect

    Whitford, G.M.; Williams, J.L.

    1986-04-01

    The concept that there are physiologic mechanisms to homeostatically regulate plasma fluoride concentrations has been supported by results in the literature suggesting an inverse relationship between plasma fluoride levels and the absorption of the ion from the gastrointestinal tract of the rat. The validity of the relationship was questioned because of possible problems in the experimental design. The present work used four different methods to evaluate the effect of plasma fluoride levels on the absorption of the ion in rats: (i) the percentage of the daily fluoride intake that was excreted in the urine; (ii) the concentration of fluoride in femur epiphyses; (iii) the net areas under the time-plasma fluoride concentration curves after intragastric fluoride doses; and (iv) the residual amounts or fluoride in the gastrointestinal tracts after the intragastric fluoride doses. None of these methods indicated that plasma fluoride levels influence the rate or the degree or fluoride absorption. It was concluded that, unless extremely high plasma fluoride levels are involved (pharmacologic or toxic doses), the absorption of the ion is independent of plasma levels. The results provide further evidence that plasma fluoride concentrations are not homeostatically regulated.

  6. Iodine absorption cells quality evaluation methods

    NASA Astrophysics Data System (ADS)

    Hrabina, Jan; Zucco, Massimo; Holá, Miroslava; Šarbort, Martin; Acef, Ouali; Du-Burck, Frédéric; Lazar, Josef; Číp, Ondřej

    2016-12-01

    The absorption cells represent an unique tool for the laser frequency stabilization. They serve as irreplaceable optical frequency references in realization of high-stable laser standards and laser sources for different brands of optical measurements, including the most precise frequency and dimensional measurement systems. One of the most often used absorption media covering visible and near IR spectral range is molecular iodine. It offers rich atlas of very strong and narrow spectral transitions which allow realization of laser systems with ultimate frequency stabilities in or below 10-14 order level. One of the most often disccussed disadvantage of the iodine cells is iodine's corrosivity and sensitivity to presence of foreign substances. The impurities react with absorption media and cause spectral shifts of absorption spectra, spectral broadening of the transitions and decrease achievable signal-to-noise ratio of the detected spectra. All of these unwanted effects directly influence frequency stability of the realized laser standard and due to this fact, the quality of iodine cells must be precisely controlled. We present a comparison of traditionally used method of laser induced fluorescence (LIF) with novel technique based on hyperfine transitions linewidths measurement. The results summarize advantages and drawbacks of these techniques and give a recommendation for their practical usage.

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

    PubMed

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

    2014-09-01

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

  8. CHLORINE ABSORPTION IN S(IV) SOLUTIONS

    EPA Science Inventory

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

  9. Absorption of light dark matter in semiconductors

    NASA Astrophysics Data System (ADS)

    Hochberg, Yonit; Lin, Tongyan; Zurek, Kathryn M.

    2017-01-01

    Semiconductors are by now well-established targets for direct detection of MeV to GeV dark matter via scattering off electrons. We show that semiconductor targets can also detect significantly lighter dark matter via an absorption process. When the dark matter mass is above the band gap of the semiconductor (around an eV), absorption proceeds by excitation of an electron into the conduction band. Below the band gap, multiphonon excitations enable absorption of dark matter in the 0.01 eV to eV mass range. Energetic dark matter particles emitted from the sun can also be probed for masses below an eV. We derive the reach for absorption of a relic kinetically mixed dark photon or pseudoscalar in germanium and silicon, and show that existing direct detection results already probe new parameter space. With only a moderate exposure, low-threshold semiconductor target experiments can exceed current astrophysical and terrestrial constraints on sub-keV bosonic dark matter.

  10. Enhanced absorption in silicon metamaterials waveguide structure

    NASA Astrophysics Data System (ADS)

    Hamouche, Houria; Shabat, Mohammed M.

    2016-07-01

    Metamaterial waveguide structures for silicon solar cells are a novel approach to antireflection coating structures that can be used for the achievement of high absorption in silicon solar cells. This paper investigates numerically the possibility of improving the performance of a planar waveguide silicon solar cell by incorporating a pair of silicon nitride/metamaterial layer between a semi-infinite glass cover layer and a semi-infinite silicon substrate layer. The optimized layer thicknesses of the pair are determined under the solar spectrum AM1.5 by the effective average reflectance method. The transmission and reflection coefficients are derived by the transfer matrix method for values of metamaterial's refractive index in visible and near-infrared radiation. In addition, the absorption coefficient is examined for several angles of incidence of the transverse electric polarized (TE), transverse magnetic polarized (TM) and the total (TE&TM) guided waves. Numerical results provide an extremely high absorption. The absorptivity of the structure achieves greater than 98 %.

  11. Direct fired absorption machine flue gas recuperator

    DOEpatents

    Reimann, Robert C.; Root, Richard A.

    1985-01-01

    A recuperator which recovers heat from a gas, generally the combustion gas of a direct-fired generator of an absorption machine. The recuperator includes a housing with liquid flowing therethrough, the liquid being in direct contact with the combustion gas for increasing the effectiveness of the heat transfer between the gas and the liquid.

  12. Absorption machine with desorber-resorber

    DOEpatents

    Biermann, Wendell J.

    1985-01-01

    An absorption refrigeration system utilizing a low temperature desorber and intermediate temperature resorber. The system operates at three temperatures and three pressures to increase the efficiency of the system and is capable of utilizing a lower generator temperature than previously used.

  13. Coupled dual loop absorption heat pump

    DOEpatents

    Sarkisian, Paul H.; Reimann, Robert C.; Biermann, Wendell J.

    1985-01-01

    A coupled dual loop absorption system which utilizes two separate complete loops. Each individual loop operates at three temperatures and two pressures. This low temperature loop absorber and condenser are thermally coupled to the high temperature loop evaporator, and the high temperature loop condenser and absorber are thermally coupled to the low temperature generator.

  14. Laser Absorption by Over-Critical Plasmas

    NASA Astrophysics Data System (ADS)

    May, J.; Tonge, J.; Fiuza, F.; Fonseca, R. A.; Silva, L. O.; Mori, W. B.

    2015-11-01

    Absorption of high intensity laser light by matter has important applications to emerging sciences and technology, such as Fast Ignition ICF and ion acceleration. As such, understanding the underlying mechanisms of this absorption is key to developing these technologies. Critical features which distinguish the interaction of high intensity light - defined here as a laser field having a normalized vector potential greater than unity - are that the reaction of the material to the fields results in sharp high-density interfaces; and that the movement of the electrons is in general relativistic, both in a fluid and a thermal sense. The results of these features are that the absorption mechanisms are qualitatively distinct from those at lower intensities. We will review previous work, by our group and others, on the absorption mechanisms, and highlight current research. We will show that the standing wave structure of the reflected laser light is key to particle dynamics for normally incident lasers. The authors acknowledge the support of the Department of Energy under contract DE-NA 0001833 and the National Science Foundation under contract ACI 1339893.

  15. Molecular absorption in transition region spectral lines

    NASA Astrophysics Data System (ADS)

    Schmit, D. J.; Innes, D.; Ayres, T.; Peter, H.; Curdt, W.; Jaeggli, S.

    2014-09-01

    Aims: We present observations from the Interface Region Imaging Spectrograph (IRIS) of absorption features from a multitude of cool atomic and molecular lines within the profiles of Si IV transition region lines. Many of these spectral lines have not previously been detected in solar spectra. Methods: We examined spectra taken from deep exposures of plage on 12 October 2013. We observed unique absorption spectra over a magnetic element which is bright in transition region line emission and the ultraviolet continuum. We compared the absorption spectra with emission spectra that is likely related to fluorescence. Results: The absorption features require a population of sub-5000 K plasma to exist above the transition region. This peculiar stratification is an extreme deviation from the canonical structure of the chromosphere-corona boundary. The cool material is not associated with a filament or discernible coronal rain. This suggests that molecules may form in the upper solar atmosphere on small spatial scales and introduces a new complexity into our understanding of solar thermal structure. It lends credence to previous numerical studies that found evidence for elevated pockets of cool gas in the chromosphere. Movies associated to Figs. 1 and 2 are available in electronic form at http://www.aanda.org

  16. Corrosion inhibitor for aqueous ammonia absorption system

    DOEpatents

    Phillips, B.A.; Whitlow, E.P.

    1998-09-22

    A method is described for inhibiting corrosion and the formation of hydrogen and thus improving absorption in an ammonia/water absorption refrigeration, air conditioning or heat pump system by maintaining the hydroxyl ion concentration of the aqueous ammonia working fluid within a selected range under anaerobic conditions at temperatures up to 425 F. This hydroxyl ion concentration is maintained by introducing to the aqueous ammonia working fluid an inhibitor in an amount effective to produce a hydroxyl ion concentration corresponding to a normality of the inhibitor relative to the water content ranging from about 0.015 N to about 0.2 N at 25 C. Also, working fluids for inhibiting the corrosion of carbon steel and resulting hydrogen formation and improving absorption in an ammonia/water absorption system under anaerobic conditions at up to 425 F. The working fluids may be aqueous solutions of ammonia and a strong base or aqueous solutions of ammonia, a strong base, and a specified buffer. 5 figs.

  17. Corrosion inhibitor for aqueous ammonia absorption system

    DOEpatents

    Phillips, Benjamin A.; Whitlow, Eugene P.

    1998-09-22

    A method of inhibiting corrosion and the formation of hydrogen and thus improving absorption in an ammonia/water absorption refrigeration, air conditioning or heat pump system by maintaining the hydroxyl ion concentration of the aqueous ammonia working fluid within a selected range under anaerobic conditions at temperatures up to 425.degree. F. This hydroxyl ion concentration is maintained by introducing to the aqueous ammonia working fluid an inhibitor in an amount effective to produce a hydroxyl ion concentration corresponding to a normality of the inhibitor relative to the water content ranging from about 0.015 N to about 0.2 N at 25.degree. C. Also, working fluids for inhibiting the corrosion of carbon steel and resulting hydrogen formation and improving absorption in an ammonia/water absorption system under anaerobic conditions at up to 425.degree. F. The working fluids may be aqueous solutions of ammonia and a strong base or aqueous solutions of ammonia, a strong base, and a specified buffer.

  18. The Absorption Refrigerator as a Thermal Transformer

    ERIC Educational Resources Information Center

    Herrmann, F.

    2009-01-01

    The absorption refrigerator can be considered a thermal transformer, that is, a device that is analogous to the electric transformer. The analogy is based on the correspondence between the extensive quantities, entropy and electric charge and the intensive variables, temperature and electric potential. (Contains 1 footnote and 6 figures.)

  19. Dietary factors affecting calcium and zinc absorption

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rickets is common in Nigerian children and responds better to calcium (Ca) than to vitamin D supplementation. We reported in previous studies in which oral isotopes were given with maize pap that Ca intakes are similarly low and Ca absorption (abs) similarly high in rachitic and non-rachitic Nigeria...

  20. Gamma ray astrophysics. [emphasizing processes and absorption

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.

    1974-01-01

    Gamma ray production processes are reviewed, including Compton scattering, synchrotron radiation, bremsstrahlung interactions, meson decay, nucleon-antinucleon annihilations, and pion production. Gamma ray absorption mechanisms through interactions with radiation and with matter are discussed, along with redshifts and gamma ray fluxes.

  1. Scattering and absorption by thin flat aerosols.

    PubMed

    Weil, H; Chu, C M

    1980-06-15

    An integral equation method is used to study spectral and polarization effects for the scattering and absorption of electromagnetic radiation incident on arbitrarily oriented flat disk aerosols of major dimension comparable to the wavelength of the radiation. Numerical results for flat plate ice crystals are presented.

  2. Absorptive coating for aluminum solar panels

    NASA Technical Reports Server (NTRS)

    Desmet, D.; Jason, A.; Parr, A.

    1979-01-01

    Method for coating forming coating of copper oxide from copper component of sheet aluminum/copper alloy provides strong durable solar heat collector panels. Copper oxide coating has solar absorption characteristics similar to black chrome and is much simpler and less costly to produce.

  3. Sound absorption by clamped poroelastic plates.

    PubMed

    Aygun, H; Attenborough, K

    2008-09-01

    Measurements and predictions have been made of the absorption coefficient and the surface acoustic impedance of poroelastic plates clamped in a large impedance tube and separated from the rigid termination by an air gap. The measured and predicted absorption coefficient and surface impedance spectra exhibit low frequency peaks. The peak frequencies observed in the absorption coefficient are close to those predicted and measured in the deflection spectra of the clamped poroelastic plates. The influences of the rigidity of the clamping conditions and the width of the air gap have been investigated. Both influences are found to be important. Increasing the rigidity of clamping reduces the low frequency absorption peaks compared with those measured for simply supported plates or plates in an intermediate clamping condition. Results for a closed cell foam plate and for two open cell foam plates made from recycled materials are presented. For identical clamping conditions and width of air gap, the results for the different materials differ as a consequence mainly of their different elasticity, thickness, and cell structure.

  4. Infrared differential absorption for atmospheric pollutant detection

    NASA Technical Reports Server (NTRS)

    Byer, R. L.

    1974-01-01

    Progress made in the generation of tunable infrared radiation and its application to remote pollutant detection by the differential absorption method are summarized. It is recognized that future remote pollutant measurements depended critically on the availability of high energy tunable transmitters. Futhermore, due to eye safety requirements, the transmitted frequency must lie in the 1.4 micron to 13 micron infrared spectral range.

  5. The saturable absorption and reverse saturable absorption properties of Cu doped zinc oxide thin films

    NASA Astrophysics Data System (ADS)

    Yao, Cheng-Bao; Wen, Xin; Li, Qiang-Hua; Yan, Xiao-Yan; Li, Jin; Zhang, Ke-Xin; Sun, Wen-Jun; Bai, Li-Na; Yang, Shou-Bin

    2017-03-01

    We present the structure and nonlinear absorption (NLA) properties of Cu-doped ZnO (CZO) films prepared by magnetron sputtering. The films were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The results show that the CZO films can maintain a wurtzite structure. Furthermore, the open-aperture (OA) Z-scan measurements of the film were carried out by nanosecond laser pulse. A transition from saturable absorption (SA) to reverse saturable absorption (RSA) was observed as the excitation intensity increasing. With good excellent nonlinear optical coefficient, the samples were expected to be the potential applications in optical devices.

  6. Development of Updated ABsorption SIMulation Software (ABSIM)

    SciTech Connect

    Yang, Zhiyao; Tang, Xin; Qu, Ming; Abdelaziz, Omar; Gluesenkamp, Kyle R

    2014-01-01

    ABsorption SIMulation, ABSIM, was developed for the simulation of absorption systems by The Oak Ridge National Laboratory during 1980s and 1990s. ABSIM provides a platform for users to investigate various cycle configurations and working fluids, to calculate their operating parameters, to predict their performance, and to compare them with each other on a uniform basis. ABSIM is indeed a very useful and accurate tool for researchers to investigate various absorption systems. However, it has not been well maintained: it is incompatible with recent operating systems; the interface needs improved user-friendliness, and the system needs better parameter setting and debugging tools to help achieve convergence. Therefore, it is highly needed to update and improve ABSIM. The paper presents recent efforts to improve ABSIM s compatibility with current operating systems, user interface, and analysis capabilities. The paper details the features and functions of the newly updated ABSIM software. The new ABSIM still uses the previously validated calculation engine of the old ABSIM. The new graphic user interfaces (GUI) were developed in Qt, which is an open source license GUI software based on C++. XML was used as the database for data storage in the new ABSIM. The new ABSIM has been designed to be easily learned and used. It has enhanced editing and construction functions, plus enhanced analysis features including parametric tables, plotting, property plots, and master panels for debugging. A single effect water/LiBr absorption system is used as a case study in this paper to illustrate the features, capabilities, and functions of the new ABSIM. This case study was actually an example system available in the old ABSIM. The new version of ABSIM will be continuously developed to include additional subroutines for the components in liquid desiccant systems. The new ABSIM will be available to public for free. The ultimate goal of the new ABSIM is to allow it to become a simulation

  7. Quantum Entanglement Molecular Absorption Spectrum Simulator

    NASA Technical Reports Server (NTRS)

    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.

  8. Absorption enhancement and total absorption in a graphene-waveguide hybrid structure

    NASA Astrophysics Data System (ADS)

    Guo, Jun; Wu, Leiming; Dai, Xiaoyu; Xiang, Yuanjiang; Fan, Dianyuan

    2017-02-01

    We propose a graphene/planar waveguide hybrid structure, and demonstrate total absorption in the visible wavelength range by means of attenuated total reflectance. The excitation of planar waveguide mode, which has strong near field enhancement and increased light interaction length with graphene, plays a vital role in total absorption. We analyze the origin and physical insight of total absorption theoretically by using an approximated reflectance, and show how to design such hybrid structure numerically. Utilizing the tunability of doped graphene, we discuss the possible application in optical modulators. We also achieve broadband absorption enhancement in near-IR range by cascading multiple graphene-waveguide hybrid structures. We believe our results will be useful not only for potential applications in optical devices, but also for studying other two-dimension materials.

  9. Terahertz absorption of dilute aqueous solutions.

    PubMed

    Heyden, Matthias; Tobias, Douglas J; Matyushov, Dmitry V

    2012-12-21

    Absorption of terahertz (THz) radiation by aqueous solutions of large solutes reports on the polarization response of their hydration shells. This is because the dipolar relaxation of the solute is dynamically frozen at these frequencies, and most of the solute-induced absorption changes, apart from the expulsion of water, are caused by interfacial water. We propose a model expressing the dipolar response of solutions in terms of a single parameter, the interface dipole moment induced in the interfacial water by electromagnetic radiation. We apply this concept to experimental THz absorption of hydrated sugars, amino acids, and proteins. None of the solutes studied here follow the expectations of dielectric theories, which predict a negative projection of the interface dipole on the external electric field. We find that this prediction is not able to describe the available experimental data, which instead suggests a nearly zero interface dipole for sugars and a more diverse pattern for amino acids. Hydrophobic amino acids, similarly to sugars, give rise to near zero interface dipoles, while strongly hydrophilic ones are best described by a positive projection of the interface dipole on the external field. The sign of the interface dipole is connected to the slope of the absorption coefficient with the solute concentration. A positive slope, implying an increase in the solution polarity relative to water, mirrors results frequently reported for protein solutions. We therefore use molecular dynamics simulations of hydrated glucose and lambda repressor protein to calculate the interface dipole moments of these solutes and the concentration dependence of the THz absorption. The absorption at THz frequencies increases with increasing solute concentration in both cases, implying a higher polarity of the solution compared to bulk water. The structure of the hydration layer, extracted from simulations, is qualitatively similar in both cases, with spatial correlations

  10. Absorption Capacity of Ammonia into Ionic Liquids for Absorption Refrigeration Applications

    NASA Astrophysics Data System (ADS)

    Ariyadi, H. M.; Coronas, A.

    2016-09-01

    In this paper ionic liquids are proposed as a novel absorbent for absorption refrigeration application with ammonia as refrigerant. The main objective of this work is to develop a measurement setup to study the absorption capacity of the ammonia vapour in ionic liquids in a pool type absorber. This investigation is essential in order to identify the most suitable ionic liquid as an absorbent for ammonia refrigerant. The ionic liquids studied in this work are combinations of two different cations ([EtOHmim]+ and [emim]+) and three different anions ([BF4]-, [NTf2]- and [EtSO4]-). The absorption processes are observed within 20 minutes in each experiment at different temperatures and pressures. The detail of the methodology and experimental setup are explained in this paper and measurement results of absorption capacity of ammonia into ionic liquid are discussed. Among all ionic liquids studied in this paper [EtOHmim]+ based ionic liquids shows higher absorption capacity than [emim]+ based ionic liquids, which means that the OH structure in the cation may improve the absorption capacity of ammonia.

  11. Absorption of Solar Radiation by Clouds: Observations Versus Models

    NASA Technical Reports Server (NTRS)

    Cess, R. D.; Zhang, M. H.; Minnis, P.; Corsetti, L.; Dutton, E. G.; Forgan, B. W.; Garber, D. P.; Gates, W. L.; Hack, J. J.; Harrison, E. F.; Jing, X.; Kiehl, J. T.; Long, C. N.; Morcrette, J.-J.; Potter, G. L.; Ramanathan, V.; Subasilar, B.; Whitlock, C. H.; Young, D. F.; Zhou, Y.

    1995-01-01

    There has been a long history of unexplained anomalous absorption of solar radiation by clouds. Collocated satellite and surface measurements of solar radiation at five geographically diverse locations showed significant solar absorption by clouds, resulting in about 25 watts per square meter more global-mean absorption by the cloudy atmosphere than predicted by theoretical models. It has often been suggested that tropospheric aerosols could increase cloud absorption. But these aerosols are temporally and spatially heterogeneous, whereas the observed cloud absorption is remarkably invariant with respect to season and location. Although its physical cause is unknown, enhanced cloud absorption substantially alters our understanding of the atmosphere's energy budget.

  12. Synopsis of Mid-latitude Radio Wave Absorption in Europe

    NASA Technical Reports Server (NTRS)

    Torkar, K. M.; Friedrich, M.

    1984-01-01

    Radio wave absorption data covering almost two years from Europe to Central Asia are presented. They are normalized by relating them to a reference absorption. Every day these normalized data are fitted to a mathematical function of geographical location in order to obtain a daily synopsis of radio wave absorption. A film of these absorption charts was made which is intended to reveal movements of absorption or absorption anomaly. In addition, radiance (temperature) data from the lower D-region are also plotted onto these charts.

  13. Determination of the molar absorptivity of NADH.

    PubMed

    McComb, R B; Bond, L W; Burnett, R W; Keech, R C; Bowers, G N

    1976-02-01

    The molar absorptivity of NADH at 340 nm has been determined by an indirect procedure in which high-purity glucose is phosphorylated by ATP in the presence of hexokinase, coupled to oxidation of the glucose-6-phosphate by NAD+ in the presence of glucose-6-phosphate dehydrogenase. The average value from 85 independent determinations is 6317 liter mol-1 cm-1 at 25 degrees C and pH 7.8. The overall uncertainty is -4.0 to +5.5 ppt (6292 to 6352 liter mol-1 cm-1), based on a standard error of the mean of 0.48 ppt and an estimate of systematic error of -2.6 to +4.1 ppt. Effects of pH, buffer, and temperature on the molar absorptivity are also reported.

  14. Ultrafast transient absorption measurements of heme proteins

    NASA Astrophysics Data System (ADS)

    Ye, Xiong; Demidov, Andrey; Wang, Wei; Christian, James; Champion, Paul

    1998-03-01

    Transient absorption spectra reveal the dynamics and intermediate states of the heme active site after ligand photodissociation, which helps clarify the physical process of ligand dissociation and geminate recombination. To measure the transient absorption spectra, we apply a femtosecond pump-probe technique with frequency resolved detection using a multichannel diode array. The femtosecond pulse output from a regenerative laser amplifier system is split in two; one beam pumps the optical parametric amplifier to produce a tunable wavelength pump pulse, the other beam generates a white light continuum that is varied in time with respect to pump pulse and probe the transient absorbance of the sample. We make a comparative study of myoglobin with different ligands, mutants and pH conditions.

  15. Broad Absorption Line Quasars and Galaxy Evolution

    NASA Astrophysics Data System (ADS)

    Wills, B. J.

    2009-12-01

    Luminous QSOs are signposts to galaxy evolution. Local supermassive black holes are the faded relics of quasars in their heyday at redshifts ˜2. Relationships between the masses of these local supermassive black holes and their host galaxy bulges reveal an intimate link, fundamental to galaxy evolution: the newly evolving galaxy fuels the seed black hole through its accretion disk and by loss of angular momentum and energy in the form of outflowing winds. As the central engine approaches Eddington luminosities, winds drive away dusty gas, revealing a luminous QSO and halting star formation in the galaxy bulge. Relativistic winds are manifested in powerful radio jets in ˜10% of quasars, and sub-relativistic winds are revealed by broad blueshifted absorption troughs in the “broad absorption line” (BAL) quasars. Historically, BALs avoid powerful radio quasars. Here we examine the BALs to investigate this inverse connection.

  16. Spectrophotometry of six broad absorption line QSOs

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

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

  17. Dust in MG II Absorption Systems

    NASA Astrophysics Data System (ADS)

    Malhotra, S.

    The dust absorption feature at 2175 AA is detected in a composite spectrum of Mg II absorbers. The composite absorber spectrum is obtained by taking the geometric mean of 92 quasar spectra after aligning them in the rest-frame of 96 absorbers. By aligning the spectra according to absorber redshifts we reinforce the spectral features of the absorbers, and smooth over possible bumps and wiggles in the emission spectra. The width of the observed absorption feature is 200-300 AA (FWHM), or 0.4-0.6 microns^{-1} and the central wavelength is 2240 AA. The Galactic dust feature has a central wavelength of 2176 AA and FWHM = 0.8-1.25 microns^{-1}. Simulations show that this discrepancy between the properties of the 2175 AA feature in Mg II absorbers and Galactic ISM can be mostly explained by the different methods used to measure them (cf. Malhotra 1997).

  18. Integrated vacuum absorption steam cycle gas separation

    DOEpatents

    Chen, Shiaguo [Champaign, IL; Lu, Yonggi [Urbana, IL; Rostam-Abadi, Massoud [Champaign, IL

    2011-11-22

    Methods and systems for separating a targeted gas from a gas stream emitted from a power plant. The gas stream is brought into contact with an absorption solution to preferentially absorb the targeted gas to be separated from the gas stream so that an absorbed gas is present within the absorption solution. This provides a gas-rich solution, which is introduced into a stripper. Low pressure exhaust steam from a low pressure steam turbine of the power plant is injected into the stripper with the gas-rich solution. The absorbed gas from the gas-rich solution is stripped in the stripper using the injected low pressure steam to provide a gas stream containing the targeted gas. The stripper is at or near vacuum. Water vapor in a gas stream from the stripper is condensed in a condenser operating at a pressure lower than the stripper to concentrate the targeted gas. Condensed water is separated from the concentrated targeted gas.

  19. A survey of ultraviolet interstellar absorption lines

    NASA Technical Reports Server (NTRS)

    Bohlin, R. C.; Jenkins, E. B.; Spitzer, L., Jr.; York, D. G.; Hill, J. K.; Savage, B. D.; Snow, T. P., Jr.

    1983-01-01

    A telescope-spectrometer on the Copernicus spacecraft made possible the measurement of many ultraviolet absorption lines produced by the interstellar gas. The present survey provides data on ultraviolet absorption lines in the spectra of 88 early-type stars. The stars observed are divided into four classes, including reddened stars, unreddened bright stars, moderately reddened bright stars, and unreddened and moderately reddened faint stars. Data are presented for equivalent width, W, radial velocity V, and rms line width, D, taking into account some 10 to 20 lines of N I, O I, Si II, P II, S II, Cl I, Cl II, Mn II, Fe II, Ni II, Cu II, and H2. The data are based on multiple scans for each line. Attention is given to details of observations, the data reduction procedure, and the computation of equivalent width, mean velocity, and velocity dispersion.

  20. Ultrahigh resolution photoacoustic microscopy via transient absorption

    PubMed Central

    Shelton, Ryan L.; Applegate, Brian E.

    2010-01-01

    We have developed a novel, hybrid imaging modality, Transient Absorption Ultrasonic Microscopy (TAUM), which takes advantage of the optical nonlinearities afforded by transient absorption to achieve ultrahigh-resolution photoacoustic microscopy. The theoretical point spread function for TAUM is functionally equivalent to confocal and two-photon fluorescence microscopy, potentially enabling cellular/subcellular photoacoustic imaging. A prototype TAUM system was designed, built, and used to image a cross-section through several capillaries in the excised cheek pouch of a Syrian Hamster. The well-resolved capillaries in the TAUM image provided experimental evidence of the spatial resolution. These results suggest that TAUM has excellent potential for producing volumetric images with cellular/subcellular resolution in three dimensions deep inside living tissue. PMID:21258499

  1. AGN warm absorption with the ATHENA

    NASA Astrophysics Data System (ADS)

    Różańska, Agata; Gronkiewicz, Dominik; Hryniewicz, Krzysztof; Adhikari, Tek Prasad; Rataj, Mirosław; Skup, Konrad

    2016-06-01

    X-ray astronomy requires satellites to make progress in searching the distribution of hot matter in the Universe. Approximately 15 years period of time is needed for full construction of the flight instrument from the mission concept up to the launch. A new generation X-ray telescope ATHENA (the Advanced Telescope for High Energy Astrophysics) was approved by European Space Agency as a large mission with a launch foreseen in 2028. In this paper we show how microcalorimeter on the board of ATHENA will help us to study warm absorption observed in active galactic nuclei (AGN). We show that future observations will allow us to identify hundreds of lines from highly ionized elements and to measure Galactic warm absorption with very high precision.

  2. [Carbohydrate absorption and malabsorption (author's transl)].

    PubMed

    Caspary, W F

    1977-06-01

    Starch is digested intraluminally by alpha-amylase to maltose, maltotriose, and alpha-limit dextrins. These products, as well as the disaccharides sucrose and lactose, undergo enzymatic hydrolysis to monosaccharides at the brush border surface. The monosaccharides enter the absorbing cell by specific transport mechanisms ("carriers"). Primary carbohydrate (CH) intolerance is characterized by the congenital or acquired absence of individual brush border enzymes or of monosaccharide "carriers" without morphologic abnormalities of the intestinal villus: lactose, sucrose and trehalose intolerance and glucose-galactose malabsorption (brush border diseases). Secondary CH intolerance arises when surface digestion and absorption are reduced due to structural changes of the intestinal mucosa: e.g., decrease or absence of villi with sprue and reduction of the absorbing surface with intestinal resection. Watery diarrhea is the lead symptom. Many drugs delay or interfere with CH absorption. This action may be viewed either as an unwanted side effect or as a welcome therapeutic principle.

  3. Absorption lineshapes of molecular aggregates revisited

    SciTech Connect

    Gelzinis, Andrius; Valkunas, Leonas; Abramavicius, Darius

    2015-04-21

    Linear absorption is the most basic optical spectroscopy technique that provides information about the electronic and vibrational degrees of freedom of molecular systems. In simulations of absorption lineshapes, often diagonal fluctuations are included using the cumulant expansion, and the off-diagonal fluctuations are accounted for either perturbatively, or phenomenologically. The accuracy of these methods is limited and their range of validity is still questionable. In this work, a systematic study of several such methods is presented by comparing the lineshapes with exact results. It is demonstrated that a non-Markovian theory for off-diagonal fluctuations, termed complex time dependent Redfield theory, gives good agreement with exact lineshapes over a wide parameter range. This theory is also computationally efficient. On the other hand, accounting for the off-diagonal fluctuations using the modified Redfield lifetimes was found to be inaccurate.

  4. Exciton absorption in narrow armchair graphene nanoribbons

    NASA Astrophysics Data System (ADS)

    Monozon, B. S.; Schmelcher, P.

    2016-11-01

    We develop an analytical approach to the exciton optical absorption for narrow gap armchair graphene nanoribbons (AGNR). We focus on the regime of dominant size quantization in combination with the attractive electron-hole interaction. An adiabatic separation of slow and fast motions leads via the two-body Dirac equation to the isolated and coupled subband approximations. Discrete and continuous exciton states are in general coupled and form quasi-Rydberg series of purely discrete and resonance type character. The corresponding oscillator strengths and widths are derived. We show that the exciton peaks are blue-shifted, become broader and increase in magnitude upon narrowing the ribbon. At the edge of a subband the singularity related to the 1D density of states is transformed into finite absorption via the presence of the exciton. Our analytical results are in good agreement with those obtained by other methods including numerical approaches. Estimates of the expected experimental values are provided for realistic AGNR.

  5. Nearedge Absorption Spectroscopy of Interplanetary Dust Particles

    SciTech Connect

    Brennan, S.; Luening, K.; Pianetta, P.; Bradley, J.; Graham, G.; Westphal, A.; Snead, C.; Dominguez, G.; /SLAC, SSRL

    2006-10-25

    Interplanetary Dust Particles (IDPs) are derived from primitive Solar System bodies like asteroids and comets. Studies of IDPs provide a window onto the origins of the solar system and presolar interstellar environments. We are using Total Reflection X-ray Fluorescence (TXRF) techniques developed for the measurement of the cleanliness of silicon wafer surfaces to analyze these particles with high detection sensitivity. In addition to elemental analysis of the particles, we have collected X-ray Absorption Near-Edge spectra in a grazing incidence geometry at the Fe and Ni absorption edges for particles placed on a silicon wafer substrate. We find that the iron is dominated by Fe{sub 2}O{sub 3}.

  6. Transient absorption of vibrationally excited ice Ih

    NASA Astrophysics Data System (ADS)

    Dokter, Adriaan M.; Bakker, Huib J.

    2008-01-01

    The ultrafast dynamics of HDO :D2O ice Ih at 180K is studied by midinfrared ultrafast pump-probe spectroscopy. The vibrational relaxation of HDO :D2O ice is observed to proceed via an intermediate state, which has a blueshifted absorption spectrum. Polarization resolved measurements reveal that the intermediate state is part of the intramolecular relaxation pathway of the HDO molecule. In addition, slow dynamics on a time scale of the order of 10-100ps is observed, related to thermally induced collective reorganizations of the ice lattice. The transient absorption line shape is analyzed within a Lippincott-Schroeder model for the OH-stretch potential. This analysis identifies the main mechanism behind the strong spectral broadening of the vOH=1→2 transition.

  7. Narrow UV Absorption Line Outflows from Quasars

    NASA Astrophysics Data System (ADS)

    Hamann, F.; Simon, L.; Rodriguez Hidalgo, P.; Capellupo, D.

    2012-08-01

    Narrow absorption line (NAL) outflows are an important yet poorly understood part of the quasar outflow phenomenon. We discuss one particular NAL outflow that has high speeds, time variability, and moderate ionizations like typical BAL flows, at an estimated location just ˜5 pc from the quasar. It also has a total column density and line widths (internal velocity dispersions) ˜100 times smaller than BALs, with no substantial X-ray absorption. We argue that radiative shielding (in the form of an X-ray/warm absorber) is not critical for the outflow acceleration and that the moderate ionizations occur in dense substructures that have an overall small volume filling factor in the flow. We also present new estimates of the overall incidence of quasar outflow lines; e.g., ˜43% of bright quasars have a C IV NAL outflow while ˜68% have a C IV outflow line of any variety (NAL, BAL, or mini-BAL).

  8. Ultraviolet Absorption by Secondary Organic Aerosols

    NASA Astrophysics Data System (ADS)

    Madronich, S.; Lee-Taylor, J. M.; Hodzic, A.; Aumont, B.

    2014-12-01

    Secondary organic aerosols (SOA) are typically formed in the atmosphere by the condensation of a myriad of intermediates from the photo-oxidation of volatile organic compounds (VOCs). Many of these partly oxidized molecules have functional groups (chromophores) that absorb at the ultraviolet (UV) wavelengths available in the troposphere (λ ≳ 290 nm). We used the explicit chemical model GECKO-A (Generator of Explicit Chemistry and Kinetics for Organics in the Atmosphere) to estimate UV absorption cross sections for the gaseous and particulate components of SOA from different precursors (biogenic and anthropogenic) and formed in different environments (low and high NOx, day and night). Model predictions are evaluated with laboratory and field measurements of SOA UV optical properties (esp. mass absorption coefficients and single scattering albedo), and implications are presented for surface UV radiation trends, urban actinic flux modification, and SOA lifetimes.

  9. Graphite filter atomizer in atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Katskov, Dmitri A.

    2007-09-01

    Graphite filter atomizers (GFA) for electrothermal atomic absorption spectrometry (ETAAS) show substantial advantages over commonly employed electrothermal vaporizers and atomizers, tube and platform furnaces, for direct determination of high and medium volatility elements in matrices associated with strong spectral and chemical interferences. Two factors provide lower limits of detection and shorter determination cycles with the GFA: the vaporization area in the GFA is separated from the absorption volume by a porous graphite partition; the sample is distributed over a large surface of a collector in the vaporization area. These factors convert the GFA into an efficient chemical reactor. The research concerning the GFA concept, technique and analytical methodology, carried out mainly in the author's laboratory in Russia and South Africa, is reviewed. Examples of analytical applications of the GFA in AAS for analysis of organic liquids and slurries, bio-samples and food products are given. Future prospects for the GFA are discussed in connection with analyses by fast multi-element AAS.

  10. Collisionless absorption in sharp-edged plasmas

    SciTech Connect

    Gibbon, P. ); Bell, A.R. )

    1992-03-09

    The absorption of subpicosecond, obliquely incident laser light is studied using a 11/2D particle-in-cell code. Density scale lengths from {ital L}/{lambda}=0.01 to 2 and laser irradiances between {ital I}{lambda}{sup 2}=10{sup 14} and 10{sup 18} W cm{sup {minus}2} {mu}m{sup 2} are considered. Vacuum heating'' (F. Brunel, Phys. Rev. Lett. 59, 52 (1987)) dominates over resonance absorption for scale lengths {ital L}/{lambda}{lt}0.1, and is most efficient when {ital v}{sub osc}/{ital c}{congruent}3.1({ital L}/{lambda}){sup 2}. Absorbed energy is carried mainly by a superhot'' electron population with {ital U}{sub hot}{similar to}({ital I}{lambda}{sup 2}){sup 1/3--1/2}.

  11. Vitamin A a absorption - nutritional aspects.

    PubMed

    Berger, S

    1975-01-01

    A brief review of the present knowledge of vitamin A (both performed and precursor forms) absorption is outlined with special emphasis on the dietary factors involved in this process. Some details are discussed related to the techniques used for measurement of vitamin A absorption from different sources and under different experimental conditions. Suggestions are also made to standardize appropriate procedure in this respect; this might enable comparisons and wide use of respective results obtained in various laboratories. Nutritional significance, including advantages or disadvantages of the liver test in these studies, is specifically highlighted with special reference to the determination of vitamin A bio-potency in various products. Some selected results and experience in this field are briefly presented.

  12. Iron absorption by small intestine of chickens.

    PubMed

    Sáiz, M P; Martí, M T; Mitjavila, M T; Planas, J

    1993-01-01

    Iron (Fe) absorption by three segments (duodenum, jejunum, and ileum) of the small intestine of chickens was studied by a perfusion technique in vivo in closed circuit using 59Fe Cl3 and was related to the histological characteristics of each segment. The serosal transfers of Fe for the duodenum and jejunum were the same (14%/cm), but significantly different (p < 0.05) from those of the ileum (9%/cm), which may be explained by the morphological and histological properties of the gut of chickens. However, the presence of Fe in blood and in liver was significantly lower after perfusion of the jejunum and ileum than after perfusion of the duodenum. It is concluded that chickens show an early adaptation of small intestine to Fe absorption in response to the considerable loss of Fe suffered during the laying process.

  13. Absorption of Thermal Neutrons in Uranium

    DOE R&D Accomplishments Database

    Creutz, E. C.; Wilson, R. R.; Wigner, E. P.

    1941-09-26

    A knowledge of the absorption processes for neutrons in uranium is important for planning a chain reaction experiment. The absorption of thermal neutrons in uranium and uranium oxide has been studied. Neutrons from the cyclotron were slowed down by passage through a graphite block. A uranium or uranium oxide sphere was placed at various positions in the block. The neutron intensity at different points in the sphere and in the graphite was measured by observing the activity induced in detectors or uranium oxide or manganese. It was found that both the fission activity in the uranium oxide and the activity induced in manganese was affected by non-thermal neutrons. An experimental correction for such effects was made by making measurements with the detectors surrounded by cadmium. After such corrections the results from three methods of procedure with the uranium oxide detectors and from the manganese detectors were consistent to within a few per cent.

  14. Nonequilibrium gas absorption in rotating permeable media

    NASA Astrophysics Data System (ADS)

    Baev, V. K.; Bazhaikin, A. N.

    2016-08-01

    The absorption of ammonia, sulfur dioxide, and carbon dioxide by water and aqueous solutions in rotating permeable media, a cellular porous disk, and a set of spaced-apart thin disks has been considered. The efficiency of cleaning air to remove these impurities is determined, and their anomalously high solubility (higher than equilibrium value) has been discovered. The results demonstrate the feasibility of designing cheap efficient rotor-type absorbers to clean gases of harmful impurities.

  15. Impedance Matched Absorptive Thermal Blocking Filters

    NASA Technical Reports Server (NTRS)

    Wollack, E. J.; Chuss, D. T.; Rostem, K.; U-Yen, K.

    2014-01-01

    We have designed, fabricated and characterized absorptive thermal blocking filters for cryogenic microwave applications. The transmission line filter's input characteristic impedance is designed to match 50O and its response has been validated from 0-to-50GHz. The observed return loss in the 0-to-20GHz design band is greater than 20 dB and shows graceful degradation with frequency. Design considerations and equations are provided that enable this approach to be scaled and modified for use in other applications.

  16. Impedance Matched Absorptive Thermal Blocking Filters

    NASA Technical Reports Server (NTRS)

    Wollack, E. J.; Chuss, D. T.; U-Yen, K.; Rostem, K.

    2014-01-01

    We have designed, fabricated and characterized absorptive thermal blocking filters for cryogenic microwave applications. The transmission line filter's input characteristic impedance is designed to match 50 Omega and its response has been validated from 0-to-50GHz. The observed return loss in the 0-to-20GHz design band is greater than 20 dB and shows graceful degradation with frequency. Design considerations and equations are provided that enable this approach to be scaled and modified for use in other applications.

  17. Nickel absorption and kinetics in human volunteers

    SciTech Connect

    Sunderman, F.W. Jr.; Hopfer, S.M. ); Sweeney, K.R. ); Marcus, A.H.; Creason, J. ); Most, B.M. )

    1989-05-01

    Mathematical modeling of the kinetics of nickel absorption, distribution, and elimination was performed in healthy human volunteers who ingested NiSO{sub 4} drinking water (Experiment 1) or added to food (Experiment 2). Nickel was analyzed by electrothermal atomic absorption spectrophotometry in serum, urine, and feces collected during 2 days before and 4 days after a specified NiSO{sub 4} dose (12 {mu}g of nickel/kg, n = 4; 18 {mu}g of nickel/kg, n = 4; or 50 {mu}g of nickel/kg, n = 1). Absorbed nickel averaged 27 {plus minus} 17% (mean {plus minus} SD) of the dose ingested in water vs. 0.7 {plus minus} 0.4% of the same dose ingested in food (a 40-fold difference); rate constants for nickel absorption, transfer, and elimination were not significantly influenced by the oral vehicle. The elimination half-time for absorbed nickel averaged 28 {plus minus} 9 hr. Renal clearance of nickel averaged 8.3 {plus minus} 2.0 ml/min/1.73 m{sup 2} in Experiment 1 and 5.8 {plus minus} 4.3 ml/min/1.73 m{sub 2} in Experiment 2. This study confirms that dietary constituents profoundly reduce the bioavailability of Ni{sup 2+} for alimentary absorption; approximately one-quarter of nickel ingested in drinking water after an over-night fast is absorbed from the human intestine and excreted in urine, compared with only 1% of nickel ingested in food. The compartmental model and kinetic parameters provided by this study will reduce the uncertainty of toxicologic risk assessments of human exposures to nickel in drinking water and food.

  18. Atmospheric ammonia: absorption by plant leaves.

    PubMed

    Hutchinson, G L; Millington, R J; Peters, D B

    1972-02-18

    By monitoring the disappearance of ammonia from an airstream flowing through a small growth chamber containing a single plant seedling, it was discovered that plant leaves absorb significant quantities of ammonia from the air, even at naturally occurring low atmospheric concentrations. The measured absorption rates of ammonia showed large diurnal fluctuations and varied somewhat among species, but differed little with the nitrogen fertility level of plants within a species.

  19. MMT Survey for Intervening Mg II Absorption

    NASA Astrophysics Data System (ADS)

    Nestor, Daniel B.; Turnshek, David A.; Rao, Sandhya M.

    2006-05-01

    We present the results from a spectroscopic survey for intervening Mg II absorption in the spectra of 381 background QSOs conducted at the MMT telescope. This survey complements our earlier SDSS EDR Mg II survey, extending our results to lower redshift (z~=0.15) and weaker Mg II λ2796 rest equivalent width (Wλ27960~=0.1 Å). We confirm two major results from that survey: the transition in the Wλ27960 distribution at Wλ27960~0.3 Å, and the Wλ27960-dependent evolution of the incidence of systems. The nature of ∂2N/∂z∂Wλ27960 is consistent with the idea that multiple physically distinct components/processes contribute to the incidence of Mg II absorption systems in a W0-dependent manner and evolve at different rates. A significant decrease in the total proper absorption cross section is detected in our MMT data for systems as weak as 1.0 Å<=Wλ27960<1.5 Å at z<~0.4. We discuss this W0-dependent evolution in the context of the evolution of galaxy structures, processes including superwinds and interactions, and damped-Lyα absorbers. We also consider the possibility that the observed redshift and Wλ27960 dependence of the incidence of absorption in spectroscopic surveys for low-ionization/neutral gas results from the effects of dust-induced extinction. Observations reported here were obtained at the MMT Observatory, a joint facility of the Smithsonian Institution and the University of Arizona.

  20. Oxalic acid decreases calcium absorption in rats

    SciTech Connect

    Weaver, C.M.; Martin, B.R.; Ebner, J.S.; Krueger, C.A.

    1987-11-01

    Calcium absorption from salts and foods intrinsically labeled with /sup 45/Ca was determined in the rat model. Calcium bioavailability was nearly 10 times greater for low oxalate kale, CaCO/sub 3/ and CaCl/sub 2/ than from CaC/sub 2/O/sub 4/ (calcium oxalate) and spinach (high in oxalates). Extrinsic and intrinsic labeling techniques gave a similar assessment of calcium bioavailability from kale but not from spinach.

  1. Remote laser evaporative molecular absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Hughes, Gary B.; Lubin, Philip; Cohen, Alexander; Madajian, Jonathan; Kulkarni, Neeraj; Zhang, Qicheng; Griswold, Janelle; Brashears, Travis

    2016-09-01

    We describe a novel method for probing bulk molecular and atomic composition of solid targets from a distant vantage. A laser is used to melt and vaporize a spot on the target. With sufficient flux, the spot temperature rises rapidly, and evaporation of surface materials occurs. The melted spot creates a high-temperature blackbody source, and ejected material creates a plume of surface materials in front of the spot. Molecular and atomic absorption occurs as the blackbody radiation passes through the ejected plume. Bulk molecular and atomic composition of the surface material is investigated by using a spectrometer to view the heated spot through the ejected plume. The proposed method is distinct from current stand-off approaches to composition analysis, such as Laser-Induced Breakdown Spectroscopy (LIBS), which atomizes and ionizes target material and observes emission spectra to determine bulk atomic composition. Initial simulations of absorption profiles with laser heating show great promise for Remote Laser-Evaporative Molecular Absorption (R-LEMA) spectroscopy. The method is well-suited for exploration of cold solar system targets—asteroids, comets, planets, moons—such as from a spacecraft orbiting the target. Spatial composition maps could be created by scanning the surface. Applying the beam to a single spot continuously produces a borehole or trench, and shallow subsurface composition profiling is possible. This paper describes system concepts for implementing the proposed method to probe the bulk molecular composition of an asteroid from an orbiting spacecraft, including laser array, photovoltaic power, heating and ablation, plume characteristics, absorption, spectrometry and data management.

  2. Understanding Energy Absorption Behaviors of Nanoporous Materials

    DTIC Science & Technology

    2008-05-23

    nanopore surface transfers from wettable to non- wettable . Under this condition, water molecules cannot enter the nanopores spontaneously. A...2 and the molecular weight of 106.17. Under ambient condition, the nanoporous carbon was non- wettable to p-Xylene, and thus the liquid cannot be...for nominally wettable nanochannel walls, would be dominant. F. Developing Solid-Like Energy Absorption Systems If the molecular size of the

  3. Oxalic acid decreases calcium absorption in rats.

    PubMed

    Weaver, C M; Martin, B R; Ebner, J S; Krueger, C A

    1987-11-01

    Calcium absorption from salts and foods intrinsically labeled with 45Ca was determined in the rat model. Calcium bioavailability was nearly 10 times greater for low oxalate kale, CaCO3 and CaCl2 than from CaC2O4 (calcium oxalate) and spinach (high in oxalates). Extrinsic and intrinsic labeling techniques gave a similar assessment of calcium bioavailability from kale but not from spinach.

  4. Physicochemical patterns of ozone absorption by wood

    NASA Astrophysics Data System (ADS)

    Mamleeva, N. A.; Lunin, V. V.

    2016-11-01

    Results from studying aspen and pine wood ozonation are presented. The effect the concentration of ozone, the reagent residence time, and the content of water in a sample of wood has on ozone consumption rate and ozone demand are analyzed. The residence time is shown to determine the degree of ozone conversion degree and the depth of substrate destruction. The main patterns of ozone absorption by wood with different moisture content are found. Ways of optimizing the ozonation of plant biomass are outlined.

  5. Search for absorption edges in superexpansion bursts

    NASA Astrophysics Data System (ADS)

    in't Zand, Jean

    2013-09-01

    Our goal is to measure with the LETGS a series of bright type-I X-ray bursts with strong photospheric radius expansion ('superexpansion') to search for absorption edges due to the ashes of nuclear burning. We request a quick TOO, to be triggered by ISS-MAXI and Swift-BAT, with a total exposure time of 100 ks to obtain the detection of about 10 bursts.

  6. Absorption coefficient instrument for turbid natural waters.

    PubMed

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

    1980-05-15

    An instrument has been developed that directly measures the multispectral absorption coefficient of turbid natural water. The design incorporates methods for compensation of variation in the internal light source intensity, correction of the spectrally dependent nature of the optical elements, and correction for variation in background light level. When used in conjunction with a spectrally matched total attenuation instrument, the spectrally dependent scattering coefficient can also be derived. Systematic errors associated with multiple scattering have been estimated using Monte Carlo techniques.

  7. Liquid for absorption of solar heat

    SciTech Connect

    Nakamura, T.; Iwamoto, Y.; Kadotani, K.; Marui, T.

    1984-11-13

    A liquid for the absorption of solar heat, useful as an heat-absorbing medium in water heaters and heat collectors comprises: a dispersing medium selected from the group consisting of propylene glycol, mixture of propylene glycol with water, mixture of propylene glycol with water and glycerin, and mixture of glycerin with water, a dispersant selected from the group consisting of polyvinylpyrrolidone, caramel, and mixture of polyvinylpyrrolidone with caramel, and a powdered activated carbon as a black coloring material.

  8. Optimized absorption imaging of mesoscopic atomic clouds

    NASA Astrophysics Data System (ADS)

    Muessel, Wolfgang; Strobel, Helmut; Joos, Maxime; Nicklas, Eike; Stroescu, Ion; Tomkovič, Jiří; Hume, David B.; Oberthaler, Markus K.

    2013-10-01

    We report on the optimization of high-intensity absorption imaging for small Bose-Einstein condensates. The imaging calibration exploits the linear scaling of the quantum projection noise with the mean number of atoms for a coherent spin state. After optimization for atomic clouds containing up to 300 atoms, we find an atom number resolution of atoms, mainly limited by photon shot noise and radiation pressure.

  9. Absorption of trapped particles by Jupiter's moons

    NASA Technical Reports Server (NTRS)

    Hess, W. N.; Birmingham, T. J.; Mead, G. D.

    1973-01-01

    Absorption effects of the four innermost moons in the radial transport equations for electrons and protons in Jupiter's magnetosphere are presented. The phase space density n at 2 R sub J for electrons with equatorial pitch angles less than 69 deg is reduced by a factor of 4.2 x 1000 when lunar absorption is included in the calculation. For protons with equatorial pitch angles less than 69 deg, the corresponding reduction factor is 3.2 x 100000. The effect of the satellites becomes progressively weaker for both electrons and protons as equatorial pitch angles of pi/2 are approached, because the likelihood of impacting a satellite becomes progressively smaller. The large density decreases which we find at the orbits of Io, Europa, and Ganymede result in corresponding particle flux decreases that should be observed by spacecraft making particle measurements in Jupiter's magnetosphere. The characteristic signature of satellite absorption should be a downward pointing cusp in the flux versus radius curve at the L-value corresponding to each satellite.

  10. Absorption of trapped particles by Jupiter's moons

    NASA Technical Reports Server (NTRS)

    Hess, W. N.; Birmingham, T. J.; Mead, G. D.

    1974-01-01

    Inclusion of absorption effects of the four innermost moons in the radial transport equations for electrons and protons in Jupiter's magnetosphere. It is found that the phase space density n at 2 Jupiter radii for electrons with equatorial pitch angles less than 69 deg is reduced by a factor of 42,000 when lunar absorption is included in the calculation. For protons with equatorial pitch angles less than 69 deg the corresponding reduction factor is 2,300,000. The effect of the satellites becomes progressively weaker for both electrons and protons as equatorial pitch angles of 90 deg are approached, because the likelihood of impacting a satellite becomes progressively smaller. The large density decreases found at the orbits of Io, Europa, and Ganymede result in corresponding particle flux decreases that should be observed by spacecraft making particle measurements in Jupiter's magnetosphere. The characteristic signature of satellite absorption should be a downward-pointing vertex in the flux versus radius curve at the L value corresponding to each satellite.

  11. Particle Simulation of ICRF Absorption in VASIMR

    NASA Astrophysics Data System (ADS)

    Ilin, Andrew; Díaz, Franklin Chang; Squire, Jared; Breizman, Boris; Carter, Mark

    2001-06-01

    We discuss computational challenges in particle simulation of the Ion-Cyclotron Resonance Heating of plasma in the Variable Specific Impulse Magnetoplasma Rocket (VASIMR). Mathematical simulation helps to design an ICRF antenna, i.e., maximize absorption of RF power into the plasma in the resonance area. In the ICRF simulation code EMIR, RF fields are expanded in a periodic Fourier sum in the azimuthal coordinate to reduce the three-dimensional problem to a weighted sum over two-dimensional solutions. Absorption is introduced in the cold plasma model by adding an imaginary collision frequency to the RF-driven frequency. The ion trajectories are followed through the static and RF fields using the particle trajectory code VASIMR. The VASIMR and EMIR codes are then iterated until convergence, then the collisional absorption parameter in the EMIR code is adjusted and the iteration is continued until the power deposited by the RF system matches the power absorbed by the ion trajectories in a global sense.

  12. KINEMATIC DISTANCE ASSIGNMENTS WITH H I ABSORPTION

    SciTech Connect

    Jones, Courtney; Dickey, John M.

    2012-07-01

    Using H I absorption spectra from the International Galactic Plane Survey, a new method is implemented to resolve the kinematic distance ambiguity for 75 H II regions with known systemic velocities from radio recombination lines. A further 40 kinematic distance determinations are made for H II region candidates without known systemic velocities through an investigation of the presence of H I absorption around the terminal velocity. New kinematic distance determinations can be used to further constrain spiral arm parameters and the location and extent of other structures in the Milky Way disk. H I absorption toward continuum sources beyond the solar circle is also investigated. Follow-up studies of H I at higher resolution than the 1' to 2' of existing Galactic Plane Surveys will provide kinematic distances to many more H II regions on the far side of the Galactic center. On the basis of the velocity channel summation technique developed in this paper, a much larger sample of H II regions will be analyzed in a future paper to remove the near-far distance ambiguity.

  13. HI absorption in nearby compact radio galaxies

    NASA Astrophysics Data System (ADS)

    Glowacki, M.; Allison, J. R.; Sadler, E. M.; Moss, V. A.; Curran, S. J.; Musaeva, A.; Deng, C.; Parry, R.; Sligo, M. C.

    2017-01-01

    HI absorption studies yield information on both AGN feeding and feedback processes. This AGN activity interacts with the neutral gas in compact radio sources, which are believed to represent the young or recently re-triggered AGN population. We present the results of a survey for HI absorption in a sample of 66 compact radio sources at 0.040 < z < 0.096 with the Australia Telescope Compact Array. In total, we obtained seven detections, five of which are new, with a large range of peak optical depths (3% to 87%). Of the detections, 71% exhibit asymmetric, broad (ΔvFWHM > 100 km s-1) features, indicative of disturbed gas kinematics. Such broad, shallow and offset features are also found within low-excitation radio galaxies which is attributed to disturbed circumnuclear gas, consistent with early-type galaxies typically devoid of a gas-rich disk. Comparing mid-infrared colours of our galaxies with HI detections indicates that narrow and deep absorption features are preferentially found in late-type and high-excitation radio galaxies in our sample. These features are attributed to gas in galactic disks. By combining XMM-Newton archival data with 21-cm data, we find support that absorbed X-ray sources may be good tracers of HI content within the host galaxy. This sample extends previous HI surveys in compact radio galaxies to lower radio luminosities and provides a basis for future work exploring the higher redshift universe.

  14. Mid-infrared FEL absorption spectra

    NASA Astrophysics Data System (ADS)

    Kozub, John A.; Feng, Bibo; Gabella, William E.

    2002-04-01

    The Vanderbilt Mark III FEL is a tunable source of high- intensity coherent mid-infrared radiation occurring as a train of picosecond pulses spaced 350ps apart. The laser beam is transported to each laboratory under vacuum, but is typically transmitted through some distance of atmosphere before reaching the target. Losses due to absorption by water vapor and CO2 can be large, and since the bandwidth of the FEL is several percent of the wavelength, the spectrum can be altered by atmospheric absorptions. In order to provide an accurate representation of the laser spectrum delivered to the target, and to investigate any non-linear effects associated with transport of the FEL beam, we have recorded the spectrum of the FEL output using a vacuum spectrometer positioned after measured lengths of atmosphere. The spectrometer is equipped with a linear pyroelectric array which provides the laser spectrum for each pulse. Absorption coefficients are being measured for laboratory air, averaged over the bandwidth of the FEL. The high peak powers of this Fel have induced damage in common infrared-transparent materials; we are also measuring damage thresholds for several materials at various wavelengths.

  15. Circadian regulators of intestinal lipid absorption

    PubMed Central

    Hussain, M. Mahmood; Pan, Xiaoyue

    2015-01-01

    Among all the metabolites present in the plasma, lipids, mainly triacylglycerol and diacylglycerol, show extensive circadian rhythms. These lipids are transported in the plasma as part of lipoproteins. Lipoproteins are synthesized primarily in the liver and intestine and their production exhibits circadian rhythmicity. Studies have shown that various proteins involved in lipid absorption and lipoprotein biosynthesis show circadian expression. Further, intestinal epithelial cells express circadian clock genes and these genes might control circadian expression of different proteins involved in intestinal lipid absorption. Intestinal circadian clock genes are synchronized by signals emanating from the suprachiasmatic nuclei that constitute a master clock and from signals coming from other environmental factors, such as food availability. Disruptions in central clock, as happens due to disruptions in the sleep/wake cycle, affect intestinal function. Similarly, irregularities in temporal food intake affect intestinal function. These changes predispose individuals to various metabolic disorders, such as metabolic syndrome, obesity, diabetes, and atherosclerosis. Here, we summarize how circadian rhythms regulate microsomal triglyceride transfer protein, apoAIV, and nocturnin to affect diurnal regulation of lipid absorption. PMID:25057097

  16. Experimental evidence against middle ear oxygen absorption.

    PubMed

    Buckingham, R A; Stuart, D R; Geick, M R; Girgis, S J; McGee, T J

    1985-04-01

    The present theory of eustachian tube (ET) function and middle ear (ME) ventilation posits that oxygen absorbed by the ME mucosa causes negative ME pressure which is relieved by periodic opening of the ET during swallowing and yawning. After developing a method to cannulate the ET of mongrel dogs we connected the cannulas hermetically to manometers. This system excluded ET function and tested the oxygen absorption capacity of the ME. When we controlled respiration and maintained blood gas PO2 and PCO2 at normal levels, we were unable to find any manometric evidence of negative pressure of gas absorption in the dog ME. Lowering the PCO2 and raising the PO2 of the blood by hyperventilation caused negative ME pressure which could be measured manometrically. We confirmed these findings with the tympanometer. Raising the PCO2 and lowering the PO2 by hypoventilation caused positive pressure in the ME. There is no evidence in these experiments that O2 absorption occurs or causes negative ME pressure in the dog. To the contrary there is evidence that elevated blood levels of the more diffusible CO2 cause an increase in the ME pressure and lowered CO2 level causes a negative ME pressure.

  17. Breaking temporal symmetries for emission and absorption

    PubMed Central

    Hadad, Yakir; Soric, Jason C.; Alu, Andrea

    2016-01-01

    Time-reversal symmetries impose stringent constraints on emission and absorption. Antennas, from radiofrequencies to optics, are bound to transmit and receive signals equally well from the same direction, making a directive antenna prone to receive echoes and reflections. Similarly, in thermodynamics Kirchhoff’s law dictates that the absorptivity and emissivity are bound to be equal in reciprocal systems at equilibrium, e(ω,θ)=a(ω,θ), with important consequences for thermal management and energy applications. This bound requires that a good absorber emits a portion of the absorbed energy back to the source, limiting its overall efficiency. Recent works have shown that weak time modulation or mechanical motion in suitably designed structures may largely break reciprocity and time-reversal symmetry. Here we show theoretically and experimentally that a spatiotemporally modulated device can be designed to have drastically different emission and absorption properties. The proposed concept may provide significant advances for compact and efficient radiofrequency communication systems, as well as for energy harvesting and thermal management when translated to infrared frequencies. PMID:26984502

  18. Falling Liquid Films in Absorption Machines

    NASA Astrophysics Data System (ADS)

    Fujita, Toshihiko

    The absorption machines of the lithium bromide-water type have recently been established as heat source equipments for residential and industrial use, which include refrigerating machines, heat pumps, and heat transformers. Several advanced cycle machines have also been proposed and tested. All of the absorption machines consist fundamentally of four kinds of heat exchangers, i.e. evaporator, absorber, generator, and condenser. The horizontal or vertical falling film system is usually applied to these heat exchangers, since the pressure drop which causes an undesirable change in the fluid temperature is relatively small in either system. The horizontal system is popular for the present, while the vertical system is going to be developed promisingly. This may save an installation space and also fit a plan for the Lorentz cycle. The purpose of this paper is to survey the available information for increasing heat and mass transfer rates in the heat exchangers of absorption machines. Emphasis is placed on the hydrodynamic characteristics of falling liquid films in absorbers and generators. The following topics are covered in this paper: 1. Characteristics of thin liquid films over horizontal tubes 2. Characteristics of wavy thin liquid films flowing down the vertical or inclined wall surface 3. Effect of the artificial surface roughness on the heat and mass transfer rates 4. Enhancement in the heat and mass transfer rates by the Marangoni convection 5. Conditions of film breakdown and the minimum wetting rates.

  19. MMI based Electro-Absorption Modulator Design

    NASA Astrophysics Data System (ADS)

    Sala, A.; Sikorski, Y.

    2007-05-01

    Electro-Absorption Modulators (EAM) are among the most important components of high-speed WDM optical communications devices and systems. During the last decade, multiple EAM designs were proposed and fabricated as stand alone devices, as part of Electro-Absorption Modulated Lasers (EML), and as part of multi component Planar Lightguide Circuits (PLC). Vast majority of all designed and fabricated EAMs employ a straight section of single mode waveguide. In this work, we present a new approach for EAM design which is based on the use of 1*1 Multimode Interference structure (MMI). We demonstrate improvements in the extinction ratio of the EAM based on a combination of electro-absorption and optical interference effects in the MMI structure. The increase in extinction ratio is not accompanied by an increase in insertion loss or chirp, nor does it lead to higher drive voltage or lower bandwidth. The MMI based EAM devices can be easily fabricated using current InP based fabrication technologies and, in-fact, allow for less stringent tolerance requirements than currently used for traditional EAM devices. To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2007.OSS07.P1.4

  20. Electronic absorptions of the benzylium cation

    NASA Astrophysics Data System (ADS)

    Dryza, Viktoras; Chalyavi, Nahid; Sanelli, Julian A.; Bieske, Evan J.

    2012-11-01

    The electronic transitions of the benzylium cation (Bz+) are investigated over the 250-550 nm range by monitoring the photodissociation of mass-selected C7H7+-Arn (n = 1, 2) complexes in a tandem mass spectrometer. The Bz+-Ar spectrum displays two distinct band systems, the S1←S0 band system extending from 370 to 530 nm with an origin at 19 067 ± 15 cm-1, and a much stronger S3←S0 band system extending from 270 to 320 nm with an origin at 32 035 ± 15 cm-1. Whereas the S1←S0 absorption exhibits well resolved vibrational progressions, the S3←S0 absorption is broad and relatively structureless. Vibronic structure of the S1←S0 system, which is interpreted with the aid of time-dependent density functional theory and Franck-Condon simulations, reflects the activity of four totally symmetric ring deformation modes (ν5, ν6, ν9, ν13). We find no evidence for the ultraviolet absorption of the tropylium cation, which according to the neon matrix spectrum should occur over the 260 - 275 nm range [A. Nagy, J. Fulara, I. Garkusha, and J. Maier, Angew. Chem., Int. Ed. 50, 3022 (2011)], 10.1002/anie.201008036.

  1. Intestinal absorption of biotin in the rat

    SciTech Connect

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

    1986-07-01

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

  2. Terahertz absorption of DNA decamer duplex.

    PubMed

    Li, Xiaowei; Globus, Tatiana; Gelmont, Boris; Salay, Luiz C; Bykhovski, Alexei

    2008-11-27

    This work combines experimental and theoretical approaches to investigate terahertz absorption spectra of the DNA formed by the sequence oligomer 5'-CCGGCGCCGG-3'. The three-dimensional structure of this self-complimentary DNA decamer has been well-studied, permitting us to perform direct identification of the low-frequency phonon modes associated with specific conformation and to conduct comprehensive computer simulations. Two modeling techniques, normal-mode analysis and nanosecond molecular dynamics with explicit solvent molecules, were employed to extract the low-frequency vibrational modes based on which the absorption spectra were calculated. The absorption spectra of the DNA decamer in aqueous solution were measured in the frequency range 10-25 cm(-1) using the terahertz Fourier transform infrared spectroscopy. Multiple well-resolved and reproducible resonance modes were observed. When calculated and experimental spectra were compared, the spectrum based on molecular dynamics simulations showed a better correlation with the experimental spectra than the one based on normal-mode analysis. These results demonstrate that there exist a considerable number of active low-frequency phonon modes in this short DNA duplex.

  3. Breaking temporal symmetries for emission and absorption

    NASA Astrophysics Data System (ADS)

    Hadad, Yakir; Soric, Jason C.; Alu, Andrea

    2016-03-01

    Time-reversal symmetries impose stringent constraints on emission and absorption. Antennas, from radiofrequencies to optics, are bound to transmit and receive signals equally well from the same direction, making a directive antenna prone to receive echoes and reflections. Similarly, in thermodynamics Kirchhoff's law dictates that the absorptivity and emissivity are bound to be equal in reciprocal systems at equilibrium, e(ω,θ)=a(ω,θ), with important consequences for thermal management and energy applications. This bound requires that a good absorber emits a portion of the absorbed energy back to the source, limiting its overall efficiency. Recent works have shown that weak time modulation or mechanical motion in suitably designed structures may largely break reciprocity and time-reversal symmetry. Here we show theoretically and experimentally that a spatiotemporally modulated device can be designed to have drastically different emission and absorption properties. The proposed concept may provide significant advances for compact and efficient radiofrequency communication systems, as well as for energy harvesting and thermal management when translated to infrared frequencies.

  4. REMOTE SENSING OF CH4 BY COMBINING LIDAR AND OPTICAL CORRELATION SPECTROSCOPY : FIRST EXPERIMENTAL RESULTS B. Thomas1, A. Miffre1, G. David1, J.P. Cariou2, P. Rairoux1 1Laboratoire de Spectrométrie Ionique et Moléculaire, CNRS, UMR 5579 Université Lyon 1, 10 rue Ada Byron, 69622 Villeurbanne, France, patrick.rairoux@univ-lyon1.fr 2Leosphere France, 14-16 rue Jean Rostand, 91400 Orsay, France, jpcariou@leosphere.fr

    NASA Astrophysics Data System (ADS)

    Thomas, B.; Miffre, A.; David, G.; Cariou, J.; Rairoux, P.

    2012-12-01

    In this contribution, we present a new methodology, called OCS-lidar, to remotely evaluate trace gas concentrations in the atmosphere (B. Thomas et al, 2012), as well as the first methane concentration measurements using this methodology. It is based on combining the Optical Correlation Spectroscopy (OCS) method with laser remote sensing technique (lidar). As displayed on figure 1, an Acoustic Optical Programmable Dispersive Filter is coupled with spectrally broadened femtosecond laser pulses to achieve the optical correlation between the emitted laser pulse and the methane absorption cross-section. In a first time, statistical and systematical errors of the OCS-lidar methodology have been evaluated thanks to a numerical model. The detection noise, interfering trace gases, temperature and pressure variations as well as laser pulse-to-pulse fluctuations have been considered. OCS-lidar simulations for methane concentration measurements have been achieved for background concentration (1.5 to 3 ppm), low (tens of ppm) and high sources (hundreds of ppm). Results show that background measurements are possible in the hour range while sources assessment and localization can be achieved in 10 minutes range up to 3 km range. Then, first methane concentration experimental measurements by using the OCS-lidar methodology will be presented. The laser source is an Oscillator Parametric Amplifier with emitting wavelength from 1.1 to 2 μm with 0.2 mJ at 1 kHz repetition rate. An AOPDF is used to generate correlated and non-correlated (or reference) signal. Experimental results on background methane concentration and on remote point source measurements will be presented, showing the achieved sensitivity and accuracy in both geophysical conditions.igure 1. Scheme of the OCS-Lidar principle. A broadened laser source centered on λ0-wavelength, with power spectral density P0, is used to create spectrally shaped power density P0M1 and P0M2, which are respectively correlated and anti

  5. Molecular aspects of intestinal calcium absorption.

    PubMed

    Diaz de Barboza, Gabriela; Guizzardi, Solange; Tolosa de Talamoni, Nori

    2015-06-21

    Intestinal Ca(2+) absorption is a crucial physiological process for maintaining bone mineralization and Ca(2+) homeostasis. It occurs through the transcellular and paracellular pathways. The first route comprises 3 steps: the entrance of Ca(2+) across the brush border membranes (BBM) of enterocytes through epithelial Ca(2+) channels TRPV6, TRPV5, and Cav1.3; Ca(2+) movement from the BBM to the basolateral membranes by binding proteins with high Ca(2+) affinity (such as CB9k); and Ca(2+) extrusion into the blood. Plasma membrane Ca(2+) ATPase (PMCA1b) and sodium calcium exchanger (NCX1) are mainly involved in the exit of Ca(2+) from enterocytes. A novel molecule, the 4.1R protein, seems to be a partner of PMCA1b, since both molecules co-localize and interact. The paracellular pathway consists of Ca(2+) transport through transmembrane proteins of tight junction structures, such as claudins 2, 12, and 15. There is evidence of crosstalk between the transcellular and paracellular pathways in intestinal Ca(2+) transport. When intestinal oxidative stress is triggered, there is a decrease in the expression of several molecules of both pathways that inhibit intestinal Ca(2+) absorption. Normalization of redox status in the intestine with drugs such as quercetin, ursodeoxycholic acid, or melatonin return intestinal Ca(2+) transport to control values. Calcitriol [1,25(OH)₂D₃] is the major controlling hormone of intestinal Ca(2+) transport. It increases the gene and protein expression of most of the molecules involved in both pathways. PTH, thyroid hormones, estrogens, prolactin, growth hormone, and glucocorticoids apparently also regulate Ca(2+) transport by direct action, indirect mechanism mediated by the increase of renal 1,25(OH)₂D₃ production, or both. Different physiological conditions, such as growth, pregnancy, lactation, and aging, adjust intestinal Ca(2+) absorption according to Ca(2+) demands. Better knowledge of the molecular details of intestinal Ca(2

  6. Encapsulation effects on carbonaceous aerosol light absorption

    SciTech Connect

    Sedlacek, A.J.; Onasch, T.; Davidovits, P.; Cross, E.; Mazzoleni, C.

    2010-03-15

    The contribution of aerosol absorption on direct radiative forcing is still an active area of research, in part, because aerosol extinction is dominated by light scattering and, in part, because the primary absorbing aerosol of interest, soot, exhibits complex aging behavior that alters its optical properties. The consequences of this can be evidenced by the work of Ramanathan and Carmichael (2008) who suggest that incorporating the atmospheric heating due to brown clouds (plumes containing soot byproducts from automobiles, biomass burning, wood-burning kitchen stoves, and coal-fired power plants) will increase black carbon (BC) radiative forcing from the Intergovernmental Panel on Climate Change best estimate of 0.34 Wm-2 (±0.25 Wm-2) (IPCC 2007) to 0.9 Wm-2. This noteworthy degree of uncertainty is due largely to the interdependence of BC optical properties on particle mixing state and aggregate morphology, each of which changes as the particle ages in the atmosphere and becomes encapsulated within a coating of inorganic and/or organic substances. In July 2008, a laboratory-based measurement campaign, led by Boston College and Aerodyne, was initiated to begin addressing this interdependence. To achieve insights into the interdependence of BC optical properties on particle mixing state and aggregate morphology, measurements of both the optical and physical properties of flame-generated soot under nascent, coated, and denuded conditions were conducted. This poster presents data on black carbon (BC) light absorption measured by Photothermal Interferometry (Sedlacek and Lee 2007). In addition to examining nascent BC—to provide a baseline measurement—encapsulation with varying thicknesses of either dioctyl sebacate (DOS) or sulfuric acid was conducted to glean insights into the interplay between particle mixing state and optical properties. Additionally, some experiments were carried out where BC was coated and then denuded. In the case of DOS-coated soot, a

  7. Computed survey spectra of 2-5 micron atmospheric absorption

    NASA Astrophysics Data System (ADS)

    Leslie, D. H.; Lebow, P. S.

    1983-08-01

    Computed high resolution survey spectra of atmospheric absorption coefficient vs wavenumber are presented covering the wavelength region 2-5 micrometers. The 1980 AFGL atmospheric absorption parameter compilation was employed with a mid-latitude, sea-level atmospheric model.

  8. Highly sensitive detection using Herriott cell for laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhao, Chongyi; Song, Guangming; Du, Yang; Zhao, Xiaojun; Wang, Wenju; Zhong, Liujun; Hu, Mai

    2016-11-01

    The tunable diode laser absorption spectroscopy combined with the long absorption path technique is a significant method to detect harmful gas. The long optical path could come true by Herriott cell reducing the size of the spectrometers. A 15 cm long Herriott cell with 28.8 m optical absorption path after 96 times reflection was designed that enhanced detection sensitivity of absorption spectroscopy. According to the theory data of calculation, Herriott cell is analyzed and simulated by softwares Matlab and Lighttools.

  9. Anomalous atmospheric absorption spectra due to water dimer

    NASA Astrophysics Data System (ADS)

    Cai, Peipei; Zhang, Hansheng; Shen, Shanxiong; Cheng, I.-Shan

    1986-11-01

    The anomalous atmospheric absorption spectra in the window wavelength region of 8-14 microns have been suggested due to the water dimer. Based on laboratory measurements, water continuum CO2 laser absorption spectra and a resonance absorption line due to the weak local wave vapor pure rotational transition have been reported. The equilibrium concentration of water dimers in the atmosphere, the electronic binding energy and the theoretical calculations for absorption attenuation have been obtained in agreement with published data.

  10. MIE SCATTERING AND ABSORPTION CROSS SECTIONS FOR ABSORBING PARTICLES,

    DTIC Science & Technology

    ELECTROMAGNETIC RADIATION , SCATTERING), (*ABSORPTION, ELECTROMAGNETIC RADIATION ), REFRACTIVE INDEX, LIGHT, PARTICLES, PARTICLE SIZE, RESONANCE, ATMOSPHERIC REFRACTION, PLANETARY ATMOSPHERES, INTERSTELLAR MATTER

  11. Split-flow regeneration in absorptive air separation

    DOEpatents

    Weimer, R.F.

    1987-11-24

    A chemical absorptive separation of air in multiple stage of absorption and desorption is performed with partial recycle of absorbent between stages of desorption necessary to match equilibrium conditions in the various stages of absorption. This allows reduced absorbent flow, reduced energy demand and reduced capital costs. 4 figs.

  12. 14 CFR 23.727 - Reserve energy absorption drop test.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Reserve energy absorption drop test. 23.727... Construction Landing Gear § 23.727 Reserve energy absorption drop test. (a) If compliance with the reserve energy absorption requirement in § 23.723(b) is shown by free drop tests, the drop height may not be...

  13. 14 CFR 27.727 - Reserve energy absorption drop test.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Reserve energy absorption drop test. 27.727 Section 27.727 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... Reserve energy absorption drop test. The reserve energy absorption drop test must be conducted as...

  14. 14 CFR 29.727 - Reserve energy absorption drop test.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Reserve energy absorption drop test. 29.727 Section 29.727 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION....727 Reserve energy absorption drop test. The reserve energy absorption drop test must be conducted...

  15. 14 CFR 23.727 - Reserve energy absorption drop test.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Reserve energy absorption drop test. 23.727... Construction Landing Gear § 23.727 Reserve energy absorption drop test. (a) If compliance with the reserve energy absorption requirement in § 23.723(b) is shown by free drop tests, the drop height may not be...

  16. 14 CFR 27.727 - Reserve energy absorption drop test.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Reserve energy absorption drop test. 27.727 Section 27.727 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... Reserve energy absorption drop test. The reserve energy absorption drop test must be conducted as...

  17. 14 CFR 29.727 - Reserve energy absorption drop test.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Reserve energy absorption drop test. 29.727 Section 29.727 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION....727 Reserve energy absorption drop test. The reserve energy absorption drop test must be conducted...

  18. Two-photon absorption in arsenic sulfide glasses

    NASA Astrophysics Data System (ADS)

    Chunaev, D. S.; Snopatin, G. E.; Plotnichenko, V. G.; Karasik, A. Ya.

    2016-10-01

    The two-photon absorption coefficient of 1047-{\\text{nm}} light in {\\text{As}}35{\\text{S}}65 chalcogenide glass has been measured. CW probe radiation has been used to observe the linear absorption in glass induced by two-photon excitation. The induced absorption lifetime was found to be ∼ 2 {\\text{ms}}.

  19. 14 CFR 25.723 - Shock absorption tests.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Shock absorption tests. 25.723 Section 25... absorption tests. (a) The analytical representation of the landing gear dynamic characteristics that is used in determining the landing loads must be validated by energy absorption tests. A range of tests...

  20. 14 CFR 25.723 - Shock absorption tests.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Shock absorption tests. 25.723 Section 25... absorption tests. (a) The analytical representation of the landing gear dynamic characteristics that is used in determining the landing loads must be validated by energy absorption tests. A range of tests...

  1. 14 CFR 25.723 - Shock absorption tests.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Shock absorption tests. 25.723 Section 25... absorption tests. (a) The analytical representation of the landing gear dynamic characteristics that is used in determining the landing loads must be validated by energy absorption tests. A range of tests...

  2. 14 CFR 23.723 - Shock absorption tests.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Shock absorption tests. 23.723 Section 23... Landing Gear § 23.723 Shock absorption tests. (a) It must be shown that the limit load factors selected... exceeded. This must be shown by energy absorption tests except that analysis based on tests conducted on...

  3. 14 CFR 23.723 - Shock absorption tests.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Shock absorption tests. 23.723 Section 23... Landing Gear § 23.723 Shock absorption tests. (a) It must be shown that the limit load factors selected... exceeded. This must be shown by energy absorption tests except that analysis based on tests conducted on...

  4. 14 CFR 23.723 - Shock absorption tests.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Shock absorption tests. 23.723 Section 23... Landing Gear § 23.723 Shock absorption tests. (a) It must be shown that the limit load factors selected... exceeded. This must be shown by energy absorption tests except that analysis based on tests conducted on...

  5. 14 CFR 25.723 - Shock absorption tests.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Shock absorption tests. 25.723 Section 25... absorption tests. (a) The analytical representation of the landing gear dynamic characteristics that is used in determining the landing loads must be validated by energy absorption tests. A range of tests...

  6. 14 CFR 23.723 - Shock absorption tests.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Shock absorption tests. 23.723 Section 23... Landing Gear § 23.723 Shock absorption tests. (a) It must be shown that the limit load factors selected... exceeded. This must be shown by energy absorption tests except that analysis based on tests conducted on...

  7. 14 CFR 25.723 - Shock absorption tests.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Shock absorption tests. 25.723 Section 25... absorption tests. (a) The analytical representation of the landing gear dynamic characteristics that is used in determining the landing loads must be validated by energy absorption tests. A range of tests...

  8. 14 CFR 23.723 - Shock absorption tests.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Shock absorption tests. 23.723 Section 23... Landing Gear § 23.723 Shock absorption tests. (a) It must be shown that the limit load factors selected... exceeded. This must be shown by energy absorption tests except that analysis based on tests conducted on...

  9. Split-flow regeneration in absorptive air separation

    DOEpatents

    Weimer, Robert F.

    1987-01-01

    A chemical absorptive separation of air in multiple stage of absorption and desorption is performed with partial recycle of absorbent between stages of desorption necessary to match equilibrium conditions in the various stages of absorption. This allows reduced absorbent flow, reduced energy demand and reduced capital costs.

  10. 14 CFR 27.727 - Reserve energy absorption drop test.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Reserve energy absorption drop test. 27.727 Section 27.727 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... Reserve energy absorption drop test. The reserve energy absorption drop test must be conducted as...

  11. 14 CFR 23.727 - Reserve energy absorption drop test.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Reserve energy absorption drop test. 23.727... Construction Landing Gear § 23.727 Reserve energy absorption drop test. (a) If compliance with the reserve energy absorption requirement in § 23.723(b) is shown by free drop tests, the drop height may not be...

  12. 14 CFR 23.727 - Reserve energy absorption drop test.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Reserve energy absorption drop test. 23.727... Construction Landing Gear § 23.727 Reserve energy absorption drop test. (a) If compliance with the reserve energy absorption requirement in § 23.723(b) is shown by free drop tests, the drop height may not be...

  13. 14 CFR 23.727 - Reserve energy absorption drop test.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Reserve energy absorption drop test. 23.727... Construction Landing Gear § 23.727 Reserve energy absorption drop test. (a) If compliance with the reserve energy absorption requirement in § 23.723(b) is shown by free drop tests, the drop height may not be...

  14. 14 CFR 29.727 - Reserve energy absorption drop test.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Reserve energy absorption drop test. 29.727 Section 29.727 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION....727 Reserve energy absorption drop test. The reserve energy absorption drop test must be conducted...

  15. 14 CFR 27.727 - Reserve energy absorption drop test.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Reserve energy absorption drop test. 27.727 Section 27.727 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... Reserve energy absorption drop test. The reserve energy absorption drop test must be conducted as...

  16. 14 CFR 29.727 - Reserve energy absorption drop test.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Reserve energy absorption drop test. 29.727 Section 29.727 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION....727 Reserve energy absorption drop test. The reserve energy absorption drop test must be conducted...

  17. 14 CFR 29.727 - Reserve energy absorption drop test.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Reserve energy absorption drop test. 29.727 Section 29.727 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION....727 Reserve energy absorption drop test. The reserve energy absorption drop test must be conducted...

  18. 14 CFR 27.727 - Reserve energy absorption drop test.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Reserve energy absorption drop test. 27.727 Section 27.727 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... Reserve energy absorption drop test. The reserve energy absorption drop test must be conducted as...

  19. Solar Absorption in a Stratosphere Perturbed by NOx Injection.

    PubMed

    Luther, F M

    1976-04-02

    The changes in the solar absorption by nitrogen dioxide and ozone induced by the injection of NO(x) (oxides of nitrogen) in the stratosphere are complementary, even though the nitrogen dioxide absorption is only a small fraction of the ozone absorption for an unperturbed stratosphere. The factors causing this effect are described, and an analysis is made of the perturbed solar radiation budget.

  20. Absorption-Enhancing Effect of Nitric Oxide on the Absorption of Hydrophobic Drugs in Rat Duodenum.

    PubMed

    Kishimoto, Hisanao; Miyazaki, Kaori; Takizawa, Yusuke; Shirasaka, Yoshiyuki; Inoue, Katsuhisa

    2016-02-01

    Nitric oxide (NO), an endogenous gas that plays a versatile role in the physiological system, has the ability to increase the intestinal absorption of water-soluble compounds through the paracellular route. However, it remains unclear whether NO can enhance the absorption of hydrophobic drugs through the transcellular route. In this study, we examined the absorption-enhancing effect of NO on intestinal permeability of hydrophobic drugs in rat intestine. The pretreatment of rat gastrointestinal sacs with NOC7, a NO-releasing reagent, significantly increased the permeation of griseofulvin from mucosa to serosa in the sacs prepared from the duodenum, but not in those prepared from the other regions such as jejunum, ileum, and colon. The absorption-enhancing effect of NOC7 on the duodenal permeation varied depending on the hydrophobicity of the drugs used. Furthermore, NOC7 treatment was found to be apparently ineffective on the griseofulvin permeation in the duodenum pretreated with dithiothreitol (DTT) that was used as a mucus remover, even though the permeation was increased by pretreatment with DTT alone. These results suggest that NO increases the absorption of hydrophobic drugs through the transcellular route in the duodenum by modulating the mucus layer function.

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

    PubMed

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

    2014-04-01

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

  2. Performance Characteristics of Hybrid Cycle Combined Absorption Heat Transformer and Absorption Refrigerating Machine

    NASA Astrophysics Data System (ADS)

    Iyoki, Shigeki; Otsuka, Shin-Ichi; Uemura, Tadashi

    In this paper, four kinds of hybrid cycles which combined the single-stage absorption refrigerating machine and four kinds of absorption heat transformers were proposed. It is possible that each of these hybrid cycles gets high temperature and low temperature from one cycle, simultaneously. As basic cycle of absorption heat transformer, the following were chosen: two kinds of single-stage absorption heat transformer and two kinds of two-stage absorption heat transformer. As a working medium-absorbent system, H2O-LiBr system, H2O-LiBr-LiNO3 system, H2O-LiBr-LiNO3-LiCl system, H2O-LiBr-C2H6O2 system and H2O-LiNO3-LiCl system were adopted. Using these five kinds of working medium-absorbent system, the performance characteristics of four kinds of hybrid cycle were simulated. And the performance characteristics of these cycles were compared.

  3. 44th Annual Anomalous Absorption Conference

    SciTech Connect

    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

  4. Nitrogen dioxide absorption in aqueous sodium sulfite

    NASA Astrophysics Data System (ADS)

    Shen, Chen Hua

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

  5. Development and physiological regulation of intestinal lipid absorption. III. Intestinal transporters and cholesterol absorption.

    PubMed

    Hui, David Y; Labonté, Eric D; Howles, Philip N

    2008-04-01

    Intestinal cholesterol absorption is modulated by transport proteins in enterocytes. Cholesterol uptake from intestinal lumen requires several proteins on apical brush-border membranes, including Niemann-Pick C1-like 1 (NPC1L1), scavenger receptor B-I, and CD36, whereas two ATP-binding cassette half transporters, ABCG5 and ABCG8, on apical membranes work together for cholesterol efflux back to the intestinal lumen to limit cholesterol absorption. NPC1L1 is essential for cholesterol absorption, but its function as a cell surface transporter or an intracellular cholesterol transport protein needs clarification. Another ATP transporter, ABCA1, is present in the basolateral membrane to mediate HDL secretion from enterocytes.

  6. Fluid absorption in isolated perfused colonic crypts.

    PubMed Central

    Singh, S K; Binder, H J; Boron, W F; Geibel, J P

    1995-01-01

    A spatial segregation of ion transport processes between crypt and surface epithelial cells is well-accepted and integrated into physiological and pathophysiological paradigms of small and large intestinal function: Absorptive processes are believed to be located in surface (and villous) cells, whereas secretory processes are believed to be present in crypt cells. Validation of this model requires direct determination of fluid movement in intestinal crypts. This study describes the adaptation of techniques from renal tubule microperfusion to hand-dissect and perfuse single, isolated crypts from rat distal colon to measure directly fluid movement. Morphologic analyses of the isolated crypt preparation revealed no extraepithelial cellular elements derived from the lamina propria, including myofibroblasts. In the basal state, crypts exhibited net fluid absorption (mean net fluid movement = 0.34 +/- 0.01 nl.mm-1.min-1), which was Na+ and partially HCO3- dependent. Addition of 1 mM dibutyryl-cyclic AMP, 60 nM vasoactive intestinal peptide, or 0.1 mM acetylcholine to the bath (serosal) solution reversibly induced net fluid secretion (net fluid movement approximately -0.35 +/- 0.01 nl.mm-1.min-1). These observations permit speculation that absorption is a constitutive transport function in crypt cells and that secretion by crypt cells is regulated by one or more neurohumoral agonists that are released in situ from lamina propria cells. The functional, intact polarized crypt described here that both absorbs and secretes will permit future studies that dissect the mechanisms that govern fluid and electrolyte movement in the colonic crypt. Images PMID:7593625

  7. An inulin-type fructan enhances calcium absorption primarily via an effect on colonic absorption in humans

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Calcium absorption efficiency and bone mineral mass are increased in adolescents who regularly consume inulin-type fructans (ITF). The mechanism of action in increasing absorption is unknown but may be related to increased colonic calcium absorption. We conducted a study in young adults designed to ...

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

    PubMed

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

    2015-01-01

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

  9. Absorption of lawsone through human skin.

    PubMed

    Kraeling, Margaret E K; Bronaugh, Robert L; Jung, Connie T

    2007-01-01

    Lawsone (2-hydroxy-1,4-naphthoquinone) is the principal color ingredient in henna, a color additive approved with limitations for coloring hair by the Food and Drug Administration (FDA) under 21 CFR 73.2190. In 2002, the scientific committee on cosmetics and non-food products (SCCNFP), now known as the scientific committee for consumer products (SCCP), evaluated the safety of lawsone as a coloring agent in hair dye products of the European Union (EU). The SCCNFP concluded that lawsone was mutagenic and not suitable for use as a hair coloring agent. As a result, studies were conducted to measure the extent of lawsone absorption through human skin. Lawsone skin absorption was determined from two hair coloring products and two shampoo products, all containing henna. [(14)C]-Lawsone (sp. act. 22.9 mCi/mmol) was added to each commercial product and the products were applied to dermatomed, nonviable human skin mounted in flow-through diffusion cells perfused with a physiological buffer (HEPES-buffered Hanks' balanced salt solution, pH 7.4). Products remained on the skin for 5 minutes (shampoos) and 1 hour (hair color paste). For the henna hair paste products, 0.3 and 1.3% of the applied dose was absorbed into the receptor fluid in 24 hours while 2.2 and 4.0% remained in the skin. For both henna shampoo products, 0.3% of the applied dose was absorbed into the receptor fluid at 24 hours while 3.6 and 6.8% remained in the skin. For all products, most of the lawsone applied was washed from the surface of the skin (83-102%) at the end of the exposure period. Extended absorption studies were conducted for 72 hours to determine if skin levels of lawsone in the 24 hour studies might eventually be percutaneously absorbed. These studies determined that the majority of the lawsone remained in the skin with only a small but significant increase (for three out of four products) in receptor fluid values. Therefore, it appears that receptor fluid values would give a good estimate of

  10. Neutron absorption cross section of uranium-236

    SciTech Connect

    Macklin, R.L.; Alexander, C.W.

    1988-11-01

    U-236 neutron absorption was measured as a function of neutron time-of-flight from 20 eV to 1 MeV. The neutron flux was monitored with a /sup 6/Li glass scintillator. Average cross sections from 3 keV to 1 MeV were derived. Estimated uncertainties were less than 5% below 600 keV and increased to 9.5% at 1 MeV. Resonance parametrization from 20 eV to a few keV remains to be done. 17 refs., 5 figs., 3 tabs.

  11. Microwave spectrometer for saturated absorption experiments.

    PubMed

    Legrand, J; Ségard, B; Krosta, A; Macke, B

    1978-04-01

    A spectrometer has been built to perform Doppler-free saturated absorption experiments in the millimeter range (30-300 GHz); a plane-cylindrical resonator between Stark plates has been used. With that device, inverted Lamb-dips have been observed at 115 GHz with a width 25 times below the Doppler width. However, the essential feature of this apparatus is to allow the application of Stark field typically of 2500 V/cm, leading to such specific uses as the Stark tuned Lamb-dip, level-crossing, and mode-crossing experiments. Typical examples are given and other applications are proposed.

  12. Distributed Bragg Reflectors With Reduced Optical Absorption

    DOEpatents

    Klem, John F.

    2005-08-16

    A new class of distributed Bragg reflectors has been developed. These distributed Bragg reflectors comprise interlayers positioned between sets of high-index and low-index quarter-wave plates. The presence of these interlayers is to reduce photon absorption resulting from spatially indirect photon-assisted electronic transitions between the high-index and low-index quarter wave plates. The distributed Bragg reflectors have applications for use in vertical-cavity surface-emitting lasers for use at 1.55 .mu.m and at other wavelengths of interest.

  13. Alfven wave absorption in dissipative plasma

    NASA Astrophysics Data System (ADS)

    Gavrikov, M. B.; Taiurskii, A. A.

    2017-01-01

    We consider nonlinear absorption of Alfven waves due to dissipative effects in plasma and relaxation of temperatures of electrons and ions. This study is based on an exact solution of the equations of two-fluid electromagnetic hydrodynamics (EMHD) of plasma. It is shown that in order to study the decay of Alfven waves, it suffices to examine the behavior of their amplitudes whose evolution is described by a system of ordinary differential equations (ODEs) obtained in this paper. On finite time intervals, the system of equations on the amplitudes is studied numerically, while asymptotic integration (the Hartman-Grobman theorem) is used to examine its large-time behavior.

  14. Gas suspension absorption as effective as scrubbing

    SciTech Connect

    Rogers, B.

    1996-01-01

    A cost-shared demonstration project undertaken jointly by AirPol Inc., the Tennessee Valley Authority, and the Department of Energy at the Shawnee Fossil Plant successfully demonstrated gas suspension absorption technology`s ability to remove more than 90% of sulfur dioxide from flue gas. The performance is roughly equivalent to wet scrubbing. The process operates with a high degree of reliability and removes almost all trace metals from the flue gas for about 30% less cost than conventional wet limestone flue gas desulfurization.

  15. Infrared absorption cross sections of alternative CFCs

    NASA Technical Reports Server (NTRS)

    Clerbaux, Cathy; Colin, Reginald; Simon, Paul C.

    1994-01-01

    Absorption cross sections have obtained in the infrared atmospheric window, between 600 and 1500 cm(exp -1), for 10 alternative hydrohalocarbons: HCFC-22, HCFC-123, HCFC-124, HCFC-141b, HCFC-142b, HCFC-225ca, HCFC-225cb, HFC-125, HFC-134a, and HFC-152a. The measurements were made at three temperatures (287K, 270K and 253K) with a Fourier transform spectrometer operating at 0.03 cm(exp -1) apodized resolution. Integrated cross sections are also derived for use in radiative models to calculate the global warming potentials.

  16. Absorption spectrometer balloon flight and iodine investigations

    NASA Technical Reports Server (NTRS)

    1970-01-01

    A high altitude balloon flight experiment to determine the technical feasibility of employing absorption spectroscopy to measure SO2 and NO2 gases in the earth's atmosphere from above the atmospheric ozone layer is discussed. In addition to the balloon experiment the contract includes a ground-based survey of natural I emissions from geological sources and studies of the feasibility of mapping I2 from spacecraft. This report is divided into three major sections as follows: (1) the planning engineering and execution of the balloon experiment, (2) data reduction and analysis of the balloon data, and (3) the results of the I2 phase of the contract.

  17. Absorption coefficient instrument for turbid natural waters

    NASA Astrophysics Data System (ADS)

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

    1980-05-01

    The paper presents an instrument that directly measures multispectral absorption coefficient of turbid natural water. Attention is given to the design, which is shown to incorporate methods for the compensation of variation in the internal light source intensity, correction of the spectrally dependent nature of the optical elements, and correction for variation in the background light level. In addition, when used in conjunction with a spectrally matched total attenuation instrument, the spectrally dependent scattering coefficient can also be derived. Finally, it is reported that systematic errors associated with multiple scattering have been estimated using Monte Carlo techniques.

  18. Absorption coefficient instrument for turbid natural waters

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

    The paper presents an instrument that directly measures multispectral absorption coefficient of turbid natural water. Attention is given to the design, which is shown to incorporate methods for the compensation of variation in the internal light source intensity, correction of the spectrally dependent nature of the optical elements, and correction for variation in the background light level. In addition, when used in conjunction with a spectrally matched total attenuation instrument, the spectrally dependent scattering coefficient can also be derived. Finally, it is reported that systematic errors associated with multiple scattering have been estimated using Monte Carlo techniques.

  19. Laser absorption waves in metallic capillaries

    NASA Astrophysics Data System (ADS)

    Anisimov, V. N.; Arutiunian, R. V.; Bol'Shov, L. A.; Kanevskii, M. F.; Kondrashov, V. V.

    1987-07-01

    The propagation of laser absorption waves in metallic capillaries was studied experimentally and numerically during pulsed exposure to CO2 laser radiation. The dependence of the plasma front propagation rate on the initial air pressure in the capillary is determined. In a broad range of parameters, the formation time of the optically opaque plasma layer is governed by the total laser pulse energy from the beginning of the exposure to the instant screening appears, and is weakly dependent on the pulse shape and gas pressure.

  20. Vacuum ultraviolet absorption in a hydrogen arcjet

    NASA Technical Reports Server (NTRS)

    Manzella, David H.; Cappelli, Mark A.

    1992-01-01

    Atomic absorption spectroscopy was utilized to measure the ground state atomic hydrogen number density in the plasma produced in a low power hydrogen arcjet. A microwave driven hydrogen plasma was used as the source of radiation resonant with the vacuum ultraviolet Lyman alpha transition. The suitability of this radiation source is discussed. The optical depth of this transition prevented measurements at locations where the ground state atomic hydrogen number density was larger than 3 x 10 exp 19/cu m. These results indicate that other single-photon optical diagnostic techniques are equally ineffective in locations of higher hydrogen number density unless the spectral line shape of the atomic hydrogen absorbers is known.

  1. Transport suction apparatus and absorption materials evaluation

    NASA Technical Reports Server (NTRS)

    Krupa, Debra T.; Gosbee, John

    1991-01-01

    The specific objectives were as follows. The effectiveness and function was evaluated of the hand held, manually powered v-vac for suction during microgravity. The function was evaluated of the battery powered laerdal suction unit in microgravity. The two units in control of various types of simulated bodily fluids were compared. Various types of tubing and attachments were evaluated which are required to control the collection of bodily fluids during transport. Various materials were evaluated for absorption of simulated bodily fluids. And potential problems were identified for waste management and containment of secretions and fluids during transport. Test procedures, results, and conclusions are briefly discussed.

  2. First attempt to monitor atmospheric glyoxal using differential absorption lidar

    NASA Astrophysics Data System (ADS)

    Mei, Liang; Lundin, Patrik; Somesfalean, Gabriel; Hu, Jiandong; Zhao, Guangyu; Svanberg, Sune; Bood, Joakim; Vrekoussis, Mihalis; Papayannis, Alexandros

    2012-11-01

    Glyoxal (CHOCHO), as an indicator of photochemical "hot spots", was for the first time the subject of a differential absorption lidar (DIAL) campaign. The strongest absorption line of glyoxal in the blue wavelength region - 455.1 nm - was chosen as the experimental absorption wavelength. In order to handle the effects of absorption cross-section variation of the interfering gas - nitrogen dioxide (NO2) - three-wavelength DIAL measurements simultaneously detecting glyoxal and NO2, were performed. The differential absorption curves, recorded in July 2012, indicate an extremely low glyoxal concentration in Lund, Sweden, although it is expected to be peaking at this time of the year.

  3. Effect of polycarbophil on the absorption of nutrients.

    PubMed

    Yamada, T; Nagata, O; Tamai, I; Tsuji, A

    1996-05-01

    The effects of polycarbophil on the absorption of various nutrients were evaluated by several in situ methods. Polycarbophil reduced the absorption of 3-O-methyl-D-glucose (3-OMG) and L-phenylalanine in the in situ loop and the in situ perfusion methods, but it did not affect the absorption of these nutrients in an open system, the in situ modified loop method, which is closer to physiological conditions. It also did not affect the absorption of vitamin A or phosphatidylcholine-L-alpha-dipalmitoyl in the latter system. These results indicate that the absorption of nutrients is probably not altered by polycarbophil under physiological conditions.

  4. Observation of the visible absorption spectrum of H2O(+)

    NASA Technical Reports Server (NTRS)

    Das, Biman; Farley, John W.

    1991-01-01

    The water cation, H2O(+), has been studied, using laser absorption spectroscopy in a velocity-modulated discharge. It is shown that it is possible to observe the absorption spectrum of an ion that is not a terminal ion, despite the weak absorption oscillator strength, and despite the use of a relatively noisy dye laser. The relative intensities of the absorption lines have been measured to an accuracy of 13 percent. It is concluded that if the absorption cross section of a single transition can be measured absolutely, then the entire manifold will be known absolutely.

  5. Accurate universal parameterization of absorption cross sections II--neutron absorption cross sections

    NASA Technical Reports Server (NTRS)

    Tripathi, R. K.; Wilson, J. W.; Cucinotta, F. A.

    1997-01-01

    A recent parameterization (here after referred as paper I, Ref. [4]) of absorption cross sections for any system of charged ions collisions including proton -nucleus collisions, is extended for neutron-nucleus collisions valid from approximately 1 MeV to a few GeV, thus providing a comprehensive picture of absorption cross sections for any system of collision pair (charged and/or uncharged). The parameters are associated with the physics of the problem. At lower energies, the optical potential at the surface is important and the Pauli operator plays an increasingly important role at intermediate energies. The agreement between the calculated and experimental data is better than earlier published results.

  6. Accurate universal parameterization of absorption cross sections II — neutron absorption cross sections

    NASA Astrophysics Data System (ADS)

    Tripathi, R. K.; Wilson, John W.; Cucinotta, Francis A.

    1997-06-01

    A recent parameterization (here after referred as paper I, Ref. [4]) of absorption cross sections for any system of charged ions collisions including proton -nucleus collisions, is extended for neutron-nucleus collisions valid from ˜ 1 MeV to a few GeV, thus providing a comprehensive picture of absorption cross sections for any system of collision pair (charged and/or uncharged). The parameters are associated with the physics of the problem. At lower energies, the optical potential at the surface is important and the Pauli operator plays an increasingly important role at intermediate energies. The agreement between the calculated and experimental data is better than earlier published results.

  7. Improved self-absorption correction for extended x-ray absorption fine-structure measurements

    SciTech Connect

    Booth, C.H.; Bridges, F.

    2003-06-04

    Extended x-ray absorption fine-structure (EXAFS) data collected in the fluorescence mode are susceptible to an apparent amplitude reduction due to the self-absorption of the fluorescing photon by the sample before it reaches a detector. Previous treatments have made the simplifying assumption that the effect of the EXAFS on the correction term is negligible, and that the samples are in the thick limit. We present a nearly exact treatment that can be applied for any sample thickness or concentration, and retains the EXAFS oscillations in the correction term.

  8. Tunable absorption in heterostructures composed of a highly absorptive metallic film and Fibonacci fractal photonic crystals

    NASA Astrophysics Data System (ADS)

    Qiao, Wei; Sun, Jie; Du, Gui-Qiang

    2016-03-01

    We have theoretically investigated the anomalous optical properties of heterostructures composed of a highly absorptive metal film and a truncated Fibonacci fractal photonic crystal. It is found that one or multiple highly reflected peaks, even enhanced transmission narrowband, can be realized in the near-complete absorption broadband, where the photonic crystals are selected with various Fibonacci sequences or a given sequence as the basic unit. These properties are significant to design important reflection or transmission optical devices in the visible and near-infrared ranges.

  9. A catalogue of absorption-line systems in QSO spectra

    NASA Astrophysics Data System (ADS)

    Ryabinkov, A. I.; Kaminker, A. D.; Varshalovich, D. A.

    2003-12-01

    We present a new catalog of absorption-line systems identified in the quasar spectra. It contains data on 821 QSOs and 8558 absorption systems comprising 16 139 absorption lines with measured redshifts in the QSO spectra. The catalog includes absorption-line systems consisting of lines of heavy elements, lines of neutral hydrogen, Lyman limit systems, damped Lyα absorption systems, and broad absorption-line systems. Using the data of the present catalog we also discuss redshift distributions of absorption-line systems. Tables 1 and 2 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/412/707

  10. Dilution cycle control for an absorption refrigeration system

    DOEpatents

    Reimann, Robert C.

    1984-01-01

    A dilution cycle control system for an absorption refrigeration system is disclosed. The control system includes a time delay relay for sensing shutdown of the absorption refrigeration system and for generating a control signal only after expiration of a preselected time period measured from the sensed shutdown of the absorption refrigeration system, during which the absorption refrigeration system is not restarted. A dilution cycle for the absorption refrigeration system is initiated in response to generation of a control signal by the time delay relay. This control system is particularly suitable for use with an absorption refrigeration system which is frequently cycled on and off since the time delay provided by the control system prevents needless dilution of the absorption refrigeration system when the system is turned off for only a short period of time and then is turned back on.

  11. Anomalous absorption of laser light on ion acoustic fluctuations

    NASA Astrophysics Data System (ADS)

    Rozmus, Wojciech; Bychenkov, Valery Yu.

    2016-10-01

    Theory of laser light absorption due to ion acoustic turbulence (IAT) is discussed in high Z plasmas where ion acoustic waves are weakly damped. Our theory applies to the whole density range from underdense to critical density plasmas. It includes an absorption rate for the resonance anomalous absorption due to linear conversion of electromagnetic waves into electron plasma oscillations by the IAT near the critical density in addition to the absorption coefficient due to enhanced effective electron collisionality. IAT is driven by large electron heat flux through the return current instability. Stationary spectra of IAT are given by weak plasma turbulence theory and applied in description of the anomalous absorption in the inertial confinement fusion plasmas at the gold walls of a hohlraum. This absorption is anisotropic in nature due to IAT angular anisotropy and differs for p- and s-polarization of the laser radiation. Possible experiments which could identify the resonance anomalous absorption in a laser heated plasma are discussed.

  12. On optimization of absorption-dispersion spectra

    NASA Astrophysics Data System (ADS)

    Hawranek, J. P.; Grabska, J.; Beć, K. B.

    2016-12-01

    A modified approach to the analysis of spectra of the complex electric permittivity of liquids in the Infrared region is presented. These spectra are derived from experimental spectra of the complex refractive index. Subsequently they are used to determine important secondary quantities, e.g. spectra of complex molecular polarizabilities and an integral property - the molar vibrational polarization. The accuracy of these quantities depends essentially on the accuracy of both components of the complex electric permittivity spectrum. In the proposed procedure, the spectra of the complex electric permittivity are approximated using the Classical Damped Harmonic Oscillator (CDHO) model for the description of individual bandshapes. The CDHO model defines both the real and imaginary part of the complex permittivity. The fitting procedure includes a simultaneous optimization of both the real and imaginary parts of the complex permittivity spectrum. A comparison of absorption-only curve fitting and the novel absorption-dispersion double curve fitting is presented; advantages of the new approach in accuracy, reliability and convergence time are pointed out. Due to the complexity of the problem, the choice was restricted to non-gradient methods of optimization. The performance of several gradientless algorithms was tested. Among numerous procedures the Powell General Least Squares Method Without Derivatives was found to be the most efficient. The reliability of obtained results of the band separatiovn process was tested on several simulated spectra of increasing complexity. The applicability of the developed approach to the analysis of exemplary experimental data was evaluated and discussed.

  13. Laser engines operating by resonance absorption.

    PubMed

    Garbuny, M; Pechersky, M J

    1976-05-01

    The coherence properties and power levels of lasers available at present lend themselves to the remote operation of mechanical engines by resonance absorption in a working gas. Laser radiation is capable of producing extremely high temperatures in a gas. Limits to the achievable temperatures in the working gas of an engine are imposed by the solid walls and by loss of resonance absorption due to thermal saturation, bleaching, and dissociation. However, it is shown that by proper control of the laser beam in space, time, and frequency, as well as by choice of the absorbing gas, these limits are to a great extent removed so that very high temperatures are indeed attainable. The working gas is largely monatomic, preferably helium with the addition of a few volume percent of an absorber. Such a gas mixture, internally heated, permits an optimization of the expansion ratio, with resulting thermal efficiencies and work ratios, not achievable in conventional engines. A relationship between thermal efficiency and work ratio is derived that is quite general for the optimization condition. The performance of laser piston engines, turbines, and the Stirling cycle based on these principles is discussed and compared with conventional engine operation. Finally, a brief discussion is devoted to the possibility and concepts for the direct conversion of selective vibrational or electronic excitation into mechanical work, bypassing the translational degrees of freedom.

  14. Earth's Atmospheric CO2 Saturated IR Absorption

    NASA Astrophysics Data System (ADS)

    Wall, Ernst

    2008-10-01

    Using the on-line SpectraCalc IR absorption simulator, the amount of IR absorption by the 15 μ line of the current atmospheric CO2 was obtained and compared with that of twice the amount of CO2. The simulation required a fixed density equivalent for the atmospheric path length. This was obtained by numerically integrating the NOAA Standard Atmospheric model. While the current line is saturated, doubling the CO2 will cause a slight width increase. Using this and the blackbody radiation curve plus considering the effects of water vapor, the temperature rise of the Earth will be less than 2.5 deg. C. Integrating a NASA Martian atmospheric model, we find that the Martian atmosphere has 45 times more CO2 to penetrate than Earth, and yet, the Martian diurnal temperature swings exceed those of the Sahara desert. I.e., large amounts of CO2 alone do not necessarily cause planetary warming. As the oceans warm from any cause, more CO2 is boiled out, but if they cool, they will absorb more CO2 just as a carbonated drink does, so that temperature and CO2 density will correlate. It is to be noted that the Earth's known petroleum reserves contain only enough CO2 to increase the atmospheric CO2 by some 15%.

  15. AGN Absorption Linked to Host Galaxies

    NASA Astrophysics Data System (ADS)

    Juneau, Stéphanie

    2014-07-01

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

  16. Absorption of solar radiation in broken clouds

    SciTech Connect

    Zuev, V.E.; Titov, G.A.; Zhuravleva, T.B.

    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.

  17. Double point contact single molecule absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Howard, John Brooks

    Our primary objective with the presentation of this thesis is to utilize superconducting transport through microscopic objects to both excite and analyze the vibrational degrees of freedom of various molecules of a biological nature. The technique stems from a Josephson junction's ability to generate radiation that falls in the terahertz gap (≈ 10 THz) and consequently can be used to excite vibrational modes of simple and complex molecules. Analysis of the change in IV characteristics coupled with the differential conductance dIdV allows determination of both the absorption spectra and the vibrational modes of biological molecules. Presented here are both the theoretical foundations of superconductivity relevant to our experimental technique and the fabrication process of our samples. Comparisons between our technique and that of other absorption spectroscopy techniques are included as a means of providing a reference upon which to judge the merits of our novel procedure. This technique is meant to improve not only our understanding of the vibrational degrees of freedom of useful biological molecules, but also these molecule's structural, electronic and mechanical properties.

  18. Dermal absorption of inorganic germanium in rats.

    PubMed

    Yokoi, Katsuhiko; Kawaai, Takae; Konomi, Aki; Uchida, Yuka

    2008-11-01

    So-called germanium 'health' products including dietary supplements, cosmetics, accessories, and warm bath service containing germanium compounds and metalloid are popular in Japan. Subchronic and chronic oral exposure of germanium dioxide (GeO(2)), popular chemical form of inorganic germanium causes severe germanium toxicosis including death and kidney dysfunction in humans and experimental animals. Intestinal absorption of neutralized GeO(2) or germanate is almost complete in humans and animals. However, it is not known whether germanium is cutaneously absorbed. We tested dermal absorption of neutralized GeO(2) or germanate using male F344/N rats. Three groups of rats were treated with a 3-h topical application of hydrophilic ointment containing graded level of neutralized GeO(2) (pH 7.4): 0, 0.21 and 0.42 mg GeO(2)/g. Germanium concentration in blood and tissues sampled from rats after topical application of inorganic germanium was measured by inductively coupled plasma-mass spectrometry. Animals topically applied 0.42 mg GeO(2)/g ointment had significantly higher germanium concentrations in plasma, liver, and kidney than those of rats that received no topical germanium. The results indicate that skin is permeable to inorganic germanium ion or germanate and recurrent exposure of germanium compounds may pose a potential health hazard.

  19. Solar absorption cooling plant in Seville

    SciTech Connect

    Bermejo, Pablo; Pino, Francisco Javier; Rosa, Felipe

    2010-08-15

    A solar/gas cooling plant at the Engineering School of Seville (Spain) was tested during the period 2008-2009. The system is composed of a double-effect LiBr + water absorption chiller of 174 kW nominal cooling capacity, powered by: (1) a pressurized hot water flow delivered by mean of a 352 m{sup 2} solar field of a linear concentrating Fresnel collector and (2) a direct-fired natural gas burner. The objective of the project is to indentify design improvements for future plants and to serve as a guideline. We focused our attention on the solar collector size and dirtiness, climatology, piping heat losses, operation control and coupling between solar collector and chiller. The daily average Fresnel collector efficiency was 0.35 with a maximum of 0.4. The absorption chiller operated with a daily average coefficient of performance of 1.1-1.25, where the solar energy represented the 75% of generator's total heat input, and the solar cooling ratio (quotient between useful cooling and insolation incident on the solar field) was 0.44. (author)

  20. Modeling optical absorption for thermoreflectance measurements

    NASA Astrophysics Data System (ADS)

    Yang, Jia; Ziade, Elbara; Schmidt, Aaron J.

    2016-03-01

    Optical pump-probe techniques based on thermoreflectance, such as time domain thermoreflectance and frequency domain thermoreflectance (FDTR), have been widely used to characterize the thermal conductivity of thin films and the thermal conductance across interfaces. These techniques typically use a transducer layer to absorb the pump light and improve the thermoreflectance signal. The transducer, however, complicates the interpretation of the measured signal because the approximation that all the energy from the pump beam is deposited at the transducer surface is not always accurate. In this paper, we consider the effect of laser absorption in the top layer of a multilayer sample, and derive an analytical solution for the thermoreflectance signal in the diffusion regime based on volumetric heating. We analyze the measurement sensitivity to the pump absorption depth for transducers with different thermal conductivities, and investigate the additional effect of probe laser penetration depth on the measured signal. We validate our model using FDTR measurements on 490 nm thick amorphous silicon films deposited on fused silica and silicon substrates.

  1. Equilibria and absorption spectra of tryptophanase.

    PubMed

    Metzler, C M; Viswanath, R; Metzler, D E

    1991-05-25

    Tryptophanase (tryptophan: indole-lyase) from Escherichia coli has been isolated in the holoenzyme form and its absorption spectra and acid-base chemistry have been reevaluated. Apoenzyme has been prepared by dialysis against sodium phosphate and L-alanine and molar absorptivities of the coenzyme bands have been estimated by readdition of pyridoxal 5'-phosphate. The spectrophotometric titration curve, whose midpoint is at pH 7.6 in 0.1 M potassium phosphate buffers, indicates some degree of cooperativity in dissociation of a pair of protons. Resolution of the computed spectra of individual ionic forms of the enzyme with lognormal distribution curves shows that band shapes are similar to those of model Schiff bases and of aspartate aminotransferase. Using molar areas from the latter we estimated amounts of individual tautomeric species. In addition to ketoenamine and enolimine or covalent adduct the high pH form also appears to contain approximately 18% of a species with a dipolar ionic ring (protonated on the ring nitrogen and with phenolate -O-). We suggest that this may be the catalytically active form of the coenzyme in tryptophanase. The equilibrium between tryptophanase and L-alanine has also been reevaluated.

  2. Millimeter wave absorption spectra of biological samples

    SciTech Connect

    Gandhi, O.P.; Hagmann, M.J.; Hill, D.W.; Partlow, L.M.; Bush, L.

    1980-01-01

    A solid-state computer-controlled system has been used to make swept-frequency measurements of absorption of biological specimens from 26.5 to 90.0 GHz. A wide range of samples was used, including solutions of DNA and RNA, and suspensions of BHK-21/C13 cells, Candida albicans, C krusei, and Escherichia coli. Sharp spectra reported by other workers were not observed. The strong absorbance of water (10--30 dB/mm) caused the absorbance of all aqueous preparations that we examined to have a water-like dependence on frequency. Reduction of incident power (to below 1.0 microW), elimination of modulation, and control of temperature to assure cell viability were not found to significantly alter the water-dominated absorbance. Frozen samples of BHK-21/C13 cells tested at dry ice and liquid nitrogen temperatures were found to have average insertion loss reduced to 0.2 dB/cm but still showed no reproducible peaks that could be attributed to absorption spectra. It is concluded that the special resonances reported by others are likely to be in error.

  3. Nonlinear Terahertz Absorption of Graphene Plasmons.

    PubMed

    Jadidi, Mohammad M; König-Otto, Jacob C; Winnerl, Stephan; Sushkov, Andrei B; Drew, H Dennis; Murphy, Thomas E; Mittendorff, Martin

    2016-04-13

    Subwavelength graphene structures support localized plasmonic resonances in the terahertz and mid-infrared spectral regimes. The strong field confinement at the resonant frequency is predicted to significantly enhance the light-graphene interaction, which could enable nonlinear optics at low intensity in atomically thin, subwavelength devices. To date, the nonlinear response of graphene plasmons and their energy loss dynamics have not been experimentally studied. We measure and theoretically model the terahertz nonlinear response and energy relaxation dynamics of plasmons in graphene nanoribbons. We employ a terahertz pump-terahertz probe technique at the plasmon frequency and observe a strong saturation of plasmon absorption followed by a 10 ps relaxation time. The observed nonlinearity is enhanced by 2 orders of magnitude compared to unpatterned graphene with no plasmon resonance. We further present a thermal model for the nonlinear plasmonic absorption that supports the experimental results. The model shows that the observed strong linearity is caused by an unexpected red shift of plasmon resonance together with a broadening and weakening of the resonance caused by the transient increase in electron temperature. The model further predicts that even greater resonant enhancement of the nonlinear response can be expected in high-mobility graphene, suggesting that nonlinear graphene plasmonic devices could be promising candidates for nonlinear optical processing.

  4. ABSORPTION MEASURE DISTRIBUTION IN Mrk 509

    SciTech Connect

    Adhikari, T. P.; Różańska, A.; Sobolewska, M.; Czerny, B.

    2015-12-20

    In this paper we model the observed absorption measure distribution (AMD) in Mrk 509, which spans three orders of magnitude in ionization level with a single-zone absorber in pressure equilibrium. AMD is usually constructed from observations of narrow absorption lines in radio-quiet active galaxies with warm absorbers. We study the properties of the warm absorber in Mrk 509 using recently published broadband spectral energy distribution observed with different instruments. This spectrum is an input in radiative transfer computations with full photoionization treatment using the titan code. We show that the simplest way to fully reproduce the shape of AMD is to assume that the warm absorber is a single zone under constant total pressure. With this assumption, we found theoretical AMD that matches the observed AMD determined on the basis of the 600 ks reflection grating spectrometer XMM-Newton spectrum of Mrk 509. The softness of the source spectrum and the important role of the free–free emission breaks the usual degeneracy in the ionization state calculations, and the explicit dependence of the depths of AMD dips on density open a new path to the density diagnostic for the warm absorber. In Mrk 509, the implied density is of the order of 10{sup 8} cm{sup −3}.

  5. Disorders of intestinal secretion and absorption.

    PubMed

    Schulzke, Jörg-Dieter; Tröger, Hanno; Amasheh, Maren

    2009-01-01

    The gastrointestinal tract possesses a huge epithelial surface area and performs many different tasks. Amongst them are the digestive and absorptive functions. Disorders of intestinal absorption and secretion comprise a variety of different diseases, e.g. coeliac disease, lactase deficiency or Whipple's disease. In principle, impaired small intestinal function can occur with or without morphological alterations of the intestinal mucosa. Therefore, in the work up of a malabsorptive syndrome an early small intestinal biopsy is encouraged in conjunction with breath tests and stool analysis to guide further management. In addition, there is an array of functional tests, the clinical availability of which becomes more and more limited. In any case, early diagnosis of the underlying pathophysiology is most important, in order to initiate proper therapy. In this chapter, diagnostic procedure of malabsorption is discussed with special attention to specific disease like coeliac disease, Whipple's disease, giardiasis and short bowel syndrome. Furthermore, bacterial overgrowth, carbohydrate malabsorption and specific nutrient malabsorption (e.g. for iron or vitamins) and protein-losing enteropathy are presented with obligatory and optional tests as used in the clinical setting.

  6. Polarization and Broad Absorption Lines in Quasars

    NASA Astrophysics Data System (ADS)

    Antonucci, Robert

    1990-12-01

    OI 287 is a unique extragalactic source. It appears to take one property from each class of object. It is either some kind of missing link, or a new type of activity. Because of the high optical polarization, OI 287 has been classified with the blazars. However, every other blazar is variable in optical flux, polarization, and polarization angle., while OI 287 is constant at V=17, P=8%, and theta=145 degrees. Also, every other blazar has a radio source dominated by an intense flat-spectrum core, while OI 287 has an upper limit of 2% of the total 20cm flux in the core. The only group of quasars which ever shows even moderate (2-5%) constant optical polarization is the broad absorption line (BAL) objects, e.g. PHL 5200 and H1413+113. Among the BAL quasars, PHL 5200 and H1413+113 have exceptionally smooth deep, attached absorption lines, and also the highest polarization. We want to know whether OI 287 is a BAL quasar. It would be the first definite radio loud example. If it is a BAL quasar then the high polarization is really related to (and perhaps the key to) the BAL phenomenon, and we can use the techniques of spectropolarimetry to help unlock the BAL geometry. The UV spectral shape would also provide help determining the cause of polarization.

  7. Absorption heat pump for space applications

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  8. Quasar Absorption Line Survey - Cycle 4 High

    NASA Astrophysics Data System (ADS)

    Bahcall, John

    1994-01-01

    The Absorption Line Survey of bright quasars provides a homogeneous data base for studying fundamental questions about the origin and evolution of gaseous systems in the universe. The initial results determine at small redshifts the number densities of Ly-ALPHA systems, of metal-lines and extragalactic halos, of Lyman-limit systems, of associated absorption systems, and the shapes and intensities of quasar emission lines and spectral energy distributions. The survey reveals that much of the sky is covered by high or very high velocity metal-line clouds present in the Galactic halo. A larger sample, which includes the requested Cycle 3 observations, is required to answer many important questions. For example, what is the correlation function of Ly-ALPHA systems at small redshifts? What fraction of the metal, the Ly-ALPHA, and the Ly-limit systems are associated with galaxies and what are the characteristic sizes of the outer gaseous regions of different types of galaxies? Do absorbing systems show evidence of the large-scale structure seen with galaxies and clusters of galaxies? The observations requested in Cycle 3 will extend the region of coverage of the Key Project sample from the redshift range of z = 0.0 to 1.0 (Cycles 1& 2) to z = 0.0 to 1.6 (Cycles 1-3). THIS FILE CONTAINS THE HIGH PRIORITY OBSERVATIONS FROM CYCLES 2 and 3 WHICH WERE NOT COMPLETED IN THOSE CYCLES.

  9. The Regulation of Iron Absorption and Homeostasis

    PubMed Central

    Wallace, Daniel F

    2016-01-01

    Iron is an essential element in biology, required for numerous cellular processes. Either too much or too little iron can be detrimental, and organisms have developed mechanisms for balancing iron within safe limits. In mammals there are no controlled mechanisms for the excretion of excess iron, hence body iron homeostasis is regulated at the sites of absorption, utilisation and recycling. This review will discuss the discoveries that have been made in the past 20 years into advancing our understanding of iron homeostasis and its regulation. The study of iron-associated disorders, such as the iron overload condition hereditary haemochromatosis and various forms of anaemia have been instrumental in increasing our knowledge in this area, as have cellular and animal model studies. The liver has emerged as the major site of systemic iron regulation, being the location where the iron regulatory hormone hepcidin is produced. Hepcidin is a negative regulator of iron absorption and recycling, achieving this by binding to the only known cellular iron exporter ferroportin and causing its internalisation and degradation, thereby reducing iron efflux from target cells and reducing serum iron levels. Much of the research in the iron metabolism field has focussed on the regulation of hepcidin and its interaction with ferroportin. The advances in this area have greatly increased our knowledge of iron metabolism and its regulation and have led to the development of novel diagnostics and therapeutics for iron-associated disorders. PMID:28303071

  10. INTESTINAL TRIGLYCERIDE ABSORPTION IN THE RAT

    PubMed Central

    Cardell, Robert R.; Badenhausen, Susan; Porter, Keith R.

    1967-01-01

    This report provides information on the morphology of fat absorption in rat intestinal epithelial cells. Three types of experiments were performed: (a) intubation of corn oil into fasted rats, (b) injection of physiological fatty-chyme prepared from fat-fed donor rats into ligated segments of jejunum of fasted animals, and (c) administration of electron-opaque particles in corn oil and markers given concurrently with the fat. These results support the hypothesis that fat is absorbed by selective diffusion of monoglycerides and fatty acids from micelles rather than by pinocytosis of unhydrolized triglycerides. Evidence is presented that the pits between the microvilli, previously believed to function in the transport of fat, are not involved in this process. Instead they appear to contribute their contents to lysosomes in the apical cytoplasm. Arguments are offered that the monoglycerides and fatty acids diffuse from the micelle while the latter is associated with the microvillous membrane of the absorptive cell. These micellar components penetrate the plasma membrane and diffuse into the cytoplasmic matrix where they encounter the SER. Triglyceride synthesis occurs in the SER and results in the deposition of fat droplets within its lumina. The synthesis of triglycerides and their sequestration into the SER establishes an inward diffusion gradient of monoglycerides and fatty acids. PMID:6033529

  11. [Decomposition of hemoglobin UV absorption spectrum into absorption spectra of prosthetic group and apoprotein by means of an additive model].

    PubMed

    Lavrinenko, I A; Vashanov, G A; Artyukhov, V G

    2015-01-01

    The decomposition pathways of hemoglobin UV absorption spectrum into the absorption spectra of the protein and non-protein components are proposed and substantiated by means of an additive model. We have established that the heme component has an absorption band with a maximum at λ(max) = 269.2 nm (ε = 97163) and the apoprotein component has an absorption band with a maximum at λ(max) = 278.4 nm (ε = 48669) for the wavelength range from 240.0 to 320.0 nm. An integral relative proportion of absorption for the heme fraction (78.8%) and apoprotein (21.2%) in the investigating wavelength range is defined.

  12. Probing low-redshift galaxies using quasar absorption lines with an emphasis on Ca II absorption

    NASA Astrophysics Data System (ADS)

    Sardane, Gendith M.

    2016-05-01

    We searched for intervening CaII absorption in nearly 95,000 quasar spectra with i≤20 from the Sloan Digital Sky Survey(SDSS) data releases DR7+DR9. Our identification of >400 CaII systems is the largest compilation of CaII absorbers in a blind search. (Abstract shortened by ProQuest.).

  13. Interstellar Mg II and C IV absorption toward Markarian 205 by NGC 4319 - An 'optically thick' QSO absorption system

    NASA Technical Reports Server (NTRS)

    Bowen, David V.; Blades, J. C.

    1993-01-01

    We have used the Goddard High-Resolution Spectrograph aboard HST to detect interstellar Mg II and C IV absorption lines toward Mrk 205, a QSO whose sightline passes within 3/h kpc of the foreground galaxy NGC 4319. Absorption is detected from both local Milky Way gas and from NGC 4319, making this the first observation of an isolated, low-redshift galaxy causing an 'optically thick' QSO absorption system. We also observed for the first time Mg II absorption from two local High Velocity Clouds along this same sightline. The data support the premise that metal absorption lines seen at higher redshift in QSO spectra originate in gas associated with intervening galaxies. However, neither the strong absorption by (half) of our own Galaxy, nor the weak absorption by NGC 4319, may be typical of absorbers in general.

  14. Photoionization-driven Absorption-line Variability in Balmer Absorption Line Quasar LBQS 1206+1052

    NASA Astrophysics Data System (ADS)

    Sun, Luming; Zhou, Hongyan; Ji, Tuo; Jiang, Peng; Liu, Bo; Liu, Wenjuan; Pan, Xiang; Shi, Xiheng; Wang, Jianguo; Wang, Tinggui; Yang, Chenwei; Zhang, Shaohua; Miller, Lauren P.

    2017-04-01

    In this paper we present an analysis of absorption-line variability in mini-BAL quasar LBQS 1206+1052. The Sloan Digital Sky Survey spectrum demonstrates that the absorption troughs can be divided into two components of blueshift velocities of ∼700 and ∼1400 km s‑1 relative to the quasar rest frame. The former component shows rare Balmer absorption, which is an indicator of high-density absorbing gas; thus, the quasar is worth follow-up spectroscopic observations. Our follow-up optical and near-infrared spectra using MMT, YFOSC, TSpec, and DBSP reveal that the strengths of the absorption lines vary for both components, while the velocities do not change. We reproduce all of the spectral data by assuming that only the ionization state of the absorbing gas is variable and that all other physical properties are invariable. The variation of ionization is consistent with the variation of optical continuum from the V-band light curve. Additionally, we cannot interpret the data by assuming that the variability is due to a movement of the absorbing gas. Therefore, our analysis strongly indicates that the absorption-line variability in LBQS 1206+1052 is photoionization driven. As shown from photoionization simulations, the absorbing gas with blueshift velocity of ∼700 km s‑1 has a density in the range of 109 to 1010 cm‑3 and a distance of ∼1 pc, and the gas with blueshift velocity of ∼1400 km s‑1 has a density of 103 cm‑3 and a distance of ∼1 kpc.

  15. Absorption Transparencies for Efficient Nonlinear Optical Generation

    NASA Astrophysics Data System (ADS)

    Hahn, Kenneth Kang-Hee

    The work presented in this thesis describes methods by which nonlinear optical generation of radiation can be enhanced with the use of absorption transparencies. Two experiments are discussed: (i) the use of a naturally occurring absorption transparency in zinc vapor for efficient generation of 104.8 nm radiation, and (ii) the creation of an induced transparency on a collisionally broadened resonance transition of lead, with which large enhancements in nonlinear optical processes may be possible. In both cases, the linear susceptibility is cancelled by a quantum interference. Since the nonlinear susceptibility does not cancel, large enhancements in nonlinear generation efficiency are possible. There is a naturally existing transparency in zinc, where two broad autoionizing levels are separated within a decay width. Because they decay predominantly to the same final continuum state, there is a sharp cancellation in both the absorption and the refractive index from the ground state. A correct choice of intermediate levels for the sum-frequency mixing process prevents a similar cancellation in the nonlinear susceptibility. We were able to generate 0.25 muJ per pulse of 104.8 nm radiation at 10 Hz using UV pump lasers with energies of about a mJ and pulse lengths of 5 ns. Unfortunately, such naturally existing transparencies are rare. However, electromagnetically induced transparencies can be created in a general manner and present the possibility of doing enhanced nonlinear optics in many systems. Especially of interest is the creation of induced transparencies on a resonance line at high densities, as such a transparency would be most useful for nonlinear optical applications. The effects of collisions need to be carefully considered, since collisional broadening is larger than lifetime broadening in such transitions. We create an induced transparency in the presence of collisions by using a strong field to couple the resonantly broadened state of lead to another

  16. [Measurement and analysis of absorption spectrum of human blood].

    PubMed

    Zhao, Zhi-Min; Xin, Yu-Jun; Wang, Le-Xin; Zhu, Wei-Hua; Zheng, Min; Guo, Xin

    2008-01-01

    The present paper puts forward a method of disease diagnosis by using the technology of spectrum analysis of human blood serum. The generation mechanism of absorption spectrum is explained and the absorption spectra of the normal blood serum and the sick blood serum are listed from the experiments of absorption spectrometry. Though the value of absorbency of the sick blood serum is almost equal to that of the normal blood serum in the most absorption spectra, there are some differences around 278 nm in the absorption spectrum. The absorbency of the blood serum with hyperglycemia is greater than that of the normal blood serum at 285 nm in the spectrum, and besides, there comes a peak shift of absorption with hyperglycemia. In the absorption spectrum of the blood serum with hypercholesterolemia, there is a clear absorption peak at 414 nm. However there is not any peak at that wavelength in the absorption spectrum of the normal blood serum. Through comparing the characters of the spectrum, we can judge if the blood sample is or not, and this blood analysis is a new method for the diagnosis of disease. Compared with other methods of blood measurements, the method of absorption spectrum analysis of blood serum presented in this paper, is more convenient for measurement, simpler for analysis, and easier to popularize.

  17. Quantitative imaging of airway liquid absorption in cystic fibrosis.

    PubMed

    Locke, Landon W; Myerburg, Michael M; Markovetz, Matthew R; Parker, Robert S; Weber, Lawrence; Czachowski, Michael R; Harding, Thomas J; Brown, Stefanie L; Nero, Joseph A; Pilewski, Joseph M; Corcoran, Timothy E

    2014-09-01

    New measures are needed to rapidly assess emerging treatments for cystic fibrosis (CF) lung disease. Using an imaging approach, we evaluated the absorptive clearance of the radiolabeled small molecule probe diethylene triamine penta-acetic acid (DTPA) as an in vivo indicator of changes in airway liquid absorption. DTPA absorption and mucociliary clearance rates were measured in 21 patients with CF (12 adults and nine children) and nine adult controls using nuclear imaging. The effect of hypertonic saline on DTPA absorption was also studied. In addition, in vitro studies were conducted to identify the determinants of transepithelial DTPA absorption. CF patients had significantly increased rates of DTPA absorption compared with control subjects but had similar mucociliary clearance rates. Treatment with hypertonic saline resulted in a decrease in DTPA absorption and an increase in mucociliary clearance in 11 out of 11 adult CF patients compared with treatment with isotonic saline. In vitro studies revealed that ∼ 50% of DTPA absorption can be attributed to transepithelial fluid transport. Apically applied mucus impedes liquid and DTPA absorption. However, mucus effects become negligible in the presence of an osmotic stimulus. Functional imaging of DTPA absorption provides a quantifiable marker of immediate response to treatments that promote airway surface liquid hydration.

  18. [Ultraviolet absorption spectra of iodine, iodide ion and triiodide ion].

    PubMed

    Wei, Yong-Ju; Liu, Cui-Ge; Mo, Li-Ping

    2005-01-01

    Ultraviolet absorption spectra of iodine I2, iodide ion I(-) and triiodide ion I3(-) were studied, and molar absorptivities of these species were determined. Absorption spectrum of I2 aqueous solution appears as an absorption peak at 203 nm with a molar absorptivity of 1.96 x 10(4) L x mol(-1) x cm(-1). Absorption spectrum of I(-) appears as two absorption peaks at 193 and 226 nm with molar absorptivities of 1.42 x 10(4) and 1.34 x 10(4) L x mol(-1) x cm(-1), respectively. When I2 aqueous solution is mixed with KI solution, two absorption peaks appear at 288 and 350 nm, respectively, indicating the formation of I3(-). Using saturation method, molar absorptivities of I3(-) at 288 and 350 nm were determined to be 3.52 x 10(4) and 2.32 x 10(4) L x mol(-1) x cm(-1), respectively.

  19. Results of measurement of radio wave absorption in the ionosphere by the AI method

    NASA Technical Reports Server (NTRS)

    Korinevskaya, N. A.

    1972-01-01

    Median noon absorption values for each month from 1964 through 1967, the diurnal variations of absorption on the regular world days, and the seasonal variations of absorption are given. The dependence of the absorption coefficient on sunspot number is analyzed.

  20. Molar absorptivity and the blank correction factor.

    PubMed

    Kroll, M H; Elin, R J

    1985-03-01

    In photometry, where both the product formed and one or several reactants absorb light at the same wavelength, the absorbance of the "blank" of the sample at the end of the reaction may be less than that measured at the beginning of the reaction, because of consumption of reactant(s). The blank correction factor for the determined result with one light-absorbing reagent is epsilon P / (epsilon P - epsilon R), where epsilon R and epsilon P are the molar absorptivities of the reagent and the product, respectively. We derived a factor for the case when more than one reagent absorbs light at the same wavelength as the measured product. This factor is independent of the concentration of reagent(s) and can correct the determined result or absorbance for the consumption of light-absorbing reagent(s) during the reaction.

  1. Continuum Absorption Coefficient of Atoms and Ions

    NASA Technical Reports Server (NTRS)

    Armaly, B. F.

    1979-01-01

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

  2. Quasar Absorption Lines and SDSS Galaxies

    NASA Astrophysics Data System (ADS)

    Shoemaker, Emileigh Suzanne; Scott, Jennifer E.; Oldak, Katarzyna

    2017-01-01

    We present the results of a study of the sightlines of 45 low redshift quasars (0.06 < z < 0.85) observed with HST/COS that lie within the footprint of the Sloan Digital Sky Survey. We use both the SDSS DR12 galaxy photometric data, including photometric redshifts, and the measured properties of the absorbers along with the known absorption characteristics of the intergalactic medium and the circumgalactic medium of galaxies to assign the most probable galaxy matches for each absorber in the sample, using estimated galaxy luminosities and virial radii as a discriminator. We show that the scheme can recover known galaxy-absorber matches found from spectroscopic data and thus provides a method for identifying likely pairs in photometric data sets as well as targets for spectroscopic follow up.

  3. Physiology of Intestinal Absorption and Secretion

    PubMed Central

    Kiela, Pawel R.; Ghishan, Fayez K.

    2016-01-01

    Virtually all nutrients from the diet are absorbed into blood across the highly polarized epithelial cell layer forming the small and large intestinal mucosa. Anatomical, histological, and functional specializations along the gastrointestinal tract are responsible for the effective and regulated nutrient transport via both passive and active mechanisms. In this chapter, we summarize the current state of knowledge regarding the mechanism of intestinal absorption of key nutrients such as sodium, anions (chloride, sulfate, oxalate), carbohydrates, amino acids and peptides, lipids, lipidand water-soluble vitamins, as well as the major minerals and micronutrients. This outline, including the molecular identity, specificity, and coordinated activities of key transport proteins and genes involved, serves as the background for the following chapters focused on the pathophysiology of acquired and congenital intestinal malabsorption, as well as clinical tools to test and treat malabsorptive symptoms. PMID:27086882

  4. Absorption band Q model for the Earth

    NASA Technical Reports Server (NTRS)

    Anderson, D. L.; Given, J. W.

    1981-01-01

    Attenuation in solids and liquids, as measured by the quality factor Q, is typically frequency dependent. In seismology, however, Q is usually assumed to be independent of frequency. Body wave, surface wave, and normal mode data are used to place constraints on the frequency dependence of Q in the mantle. Specific features of the absorption band model are: low-Q in the seismic band at both the top and the base of the mantle, low-Q for long-period body waves in the outer core, an inner core Q sub s that increases with period, and low Q sub p/Q sub s at short periods in the middle mantle.

  5. Mechanical Energy Absorption of Pectin Films

    NASA Astrophysics Data System (ADS)

    Zsivanovits, G.

    2007-04-01

    Pectin film samples were prepared from HM, LM and amidated pectins produced by CP Kelco and Danisco, with acidic and enzymatic de-esterification and amidation. The swelling of samples were indicated by hydration before the experiments for 24 h by PEG20000 solution, on known osmotic pressure, with Ca, Mg and K ions with different concentrations. Mechanical tests were followed by Stable Micro Systems penetrometer, with stress-relaxation method, in elastic deformation section. Results show, that the energy absorption depends on the pectin type, on the hydration and the ion concentration. Based on this type experiments it is possible to choose the best pectin type for different uses - as a packaging material in different occasions, or modeling pectin changes during physiological changing in the cell-wall etc.

  6. Electron heating due to resonant absorption

    SciTech Connect

    Mizuno, K.; Spielman, R.B.; DeGroot, J.S.; Bollen, W.M.

    1980-01-01

    Intense, p-polarized microwaves (v/sub os//v/sub eo-/<1) are incident on an imhomogeneous plasma (10/sup 2/absorption near the critical surface (where the plasma frequency equals microwave frequency). Suprathermal electrons are heated by resonantly driven electrostatic field to produce a hot Maxwellian distribution. Most of the heated electrons flow towards the overdense region and are absorbed by the anode at the far end of the overdense region. At high power (v/sub os//v/sub eo-/>0.2), strong heating of thermal electrons, large amplitude ion acoustic turbulence, and a self-consistent dc electric field are observed near the critical surface. This dc electric field is enhanced by applying a weak magnetic field (..omega../sub ce//..omega../sub o/ approx. = 10/sup -2/).

  7. Microwave absorption properties of pyrolytic carbon nanofilm

    PubMed Central

    2013-01-01

    We analyzed the electromagnetic (EM) shielding effectiveness in the Ka band (26 to 37 GHz) of highly amorphous nanometrically thin pyrolytic carbon (PyC) films with lateral dimensions of 7.2 × 3.4 mm2, which consists of randomly oriented and intertwined graphene flakes with a typical size of a few nanometers. We discovered that the manufactured PyC films, whose thickness is thousand times less than the skin depth of conventional metals, provide a reasonably high EM attenuation. The latter is caused by absorption losses that can be as high as 38% to 20% in the microwave frequency range. Being semi-transparent in visible and infrared spectral ranges and highly conductive at room temperature, PyC films emerge as a promising material for manufacturing ultrathin microwave (e.g., Ka band) filters and shields. PMID:23388194

  8. Vaginal absorption of hexachlorophene during labor.

    PubMed

    Strickland, D M; Leonard, R G; Stavchansky, S; Benoit, T; Wilson, R T

    1983-12-01

    Surgical soap that contains hexachlorophene is used as an antiseptic lubricant for vaginal examinations during labor in some centers. Theoretically, hexachlorophene can be absorbed from the vaginal mucosa and be potentially toxic to the fetus and neonate. To evaluate vaginal absorption and placental transfer of hexachlorophene, we measured levels in mixed arterial/venous cord serum and postpartum maternal serum in 28 women whose vaginal examinations were lubricated with pHisoHex during labor. The serum of 12 women had detectable levels of hexachlorophene, with a high level of 942 ng/ml. Cord serum had detectable levels in nine neonates, with a high level of 617 ng/ml. The conclusion is that hexachlorophene from vaginal lubricants is variably absorbed from the vaginal mucosa, and appreciable amounts can be detected in maternal and cord serum. Because of the potential for neonatal hexachlorophene toxicity, we recommend the use of alternative lubricants for pelvic examinations during labor.

  9. Anisotropic Absorption of Pure Spin Currents.

    PubMed

    Baker, A A; Figueroa, A I; Love, C J; Cavill, S A; Hesjedal, T; van der Laan, G

    2016-01-29

    Spin transfer in magnetic multilayers offers the possibility of ultrafast, low-power device operation. We report a study of spin pumping in spin valves, demonstrating that a strong anisotropy of spin pumping from the source layer can be induced by an angular dependence of the total Gilbert damping parameter, α, in the spin sink layer. Using lab- and synchrotron-based ferromagnetic resonance, we show that an in-plane variation of damping in a crystalline Co_{50}Fe_{50} layer leads to an anisotropic α in a polycrystalline Ni_{81}Fe_{19} layer. This anisotropy is suppressed above the spin diffusion length in Cr, which is found to be 8 nm, and is independent of static exchange coupling in the spin valve. These results offer a valuable insight into the transmission and absorption of spin currents, and a mechanism by which enhanced spin torques and angular control may be realized for next-generation spintronic devices.

  10. Performance bound for quantum absorption refrigerators

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    An implementation of quantum absorption chillers with three qubits has been recently proposed that is ideally able to reach the Carnot performance regime. Here we study the working efficiency of such self-contained refrigerators, adopting a consistent treatment of dissipation effects. We demonstrate that the coefficient of performance at maximum cooling power is upper bounded by 3/4 of the Carnot performance. The result is independent of the details of the system and the equilibrium temperatures of the external baths. We provide design prescriptions that saturate the bound in the limit of a large difference between the operating temperatures. Our study suggests that delocalized dissipation, which must be taken into account for a proper modeling of the machine-baths interaction, is a fundamental source of irreversibility which prevents the refrigerator from approaching the Carnot performance arbitrarily closely in practice. The potential role of quantum correlations in the operation of these machines is also investigated.

  11. Counterflow absorber for an absorption refrigeration system

    DOEpatents

    Reimann, Robert C.

    1984-01-01

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

  12. In vivo absorption spectroscopy for absolute measurement.

    PubMed

    Furukawa, Hiromitsu; Fukuda, Takashi

    2012-10-01

    In in vivo spectroscopy, there are differences between individual subjects in parameters such as tissue scattering and sample concentration. We propose a method that can provide the absolute value of a particular substance concentration, independent of these individual differences. Thus, it is not necessary to use the typical statistical calibration curve, which assumes an average level of scattering and an averaged concentration over individual subjects. This method is expected to greatly reduce the difficulties encountered during in vivo measurements. As an example, for in vivo absorption spectroscopy, the method was applied to the reflectance measurement in retinal vessels to monitor their oxygen saturation levels. This method was then validated by applying it to the tissue phantom under a variety of absorbance values and scattering efficiencies.

  13. Solar Absorptance of Cermet Coatings Evaluated

    NASA Technical Reports Server (NTRS)

    Jaworske, Donald A.

    2004-01-01

    Cermet coatings, molecular mixtures of metal and ceramic, are being considered for the heat inlet surface of solar Stirling convertors. In this application, the key role of the cermet coating is to absorb as much of the incident solar energy as possible. To achieve this objective, the cermet coating has a high solar absorptance value. Cermet coatings are manufactured utilizing sputter deposition, and many different metal and ceramic combinations can be created. The ability to mix metal and ceramic at the atomic level offers the opportunity to tailor the composition, and hence, the optical properties of these coatings. The NASA Glenn Research Center has prepared and characterized a wide variety of cermet coatings utilizing different metals deposited in an aluminum oxide ceramic matrix. In addition, the atomic oxygen durability of these coatings has been evaluated.

  14. Neural Network Solutions to Optical Absorption Spectra

    NASA Astrophysics Data System (ADS)

    Rosenbrock, Conrad

    2012-10-01

    Artificial neural networks have been effective in reducing computation time while achieving remarkable accuracy for a variety of difficult physics problems. Neural networks are trained iteratively by adjusting the size and shape of sums of non-linear functions by varying the function parameters to fit results for complex non-linear systems. For smaller structures, ab initio simulation methods can be used to determine absorption spectra under field perturbations. However, these methods are impractical for larger structures. Designing and training an artificial neural network with simulated data from time-dependent density functional theory may allow time-dependent perturbation effects to be calculated more efficiently. I investigate the design considerations and results of neural network implementations for calculating perturbation-coupled electron oscillations in small molecules.

  15. Gas separation using ultrasound and light absorption

    DOEpatents

    Sinha, Dipen N [Los Alamos, NM

    2012-07-31

    An apparatus and method for separating a chosen gas from a mixture of gases having no moving parts and utilizing no chemical processing is described. The separation of particulates from fluid carriers thereof has been observed using ultrasound. In a similar manner, molecular species may be separated from carrier species. It is also known that light-induced drift may separate light-absorbing species from carrier species. Therefore, the combination of temporally pulsed absorption of light with ultrasonic concentration is expected to significantly increase the efficiency of separation by ultrasonic concentration alone. Additionally, breaking the spatial symmetry of a cylindrical acoustic concentrator decreases the spatial distribution of the concentrated particles, and increases the concentration efficiency.

  16. Anisotropic Absorption of Pure Spin Currents

    NASA Astrophysics Data System (ADS)

    Baker, A. A.; Figueroa, A. I.; Love, C. J.; Cavill, S. A.; Hesjedal, T.; van der Laan, G.

    2016-01-01

    Spin transfer in magnetic multilayers offers the possibility of ultrafast, low-power device operation. We report a study of spin pumping in spin valves, demonstrating that a strong anisotropy of spin pumping from the source layer can be induced by an angular dependence of the total Gilbert damping parameter, α , in the spin sink layer. Using lab- and synchrotron-based ferromagnetic resonance, we show that an in-plane variation of damping in a crystalline Co50 Fe50 layer leads to an anisotropic α in a polycrystalline Ni81 Fe19 layer. This anisotropy is suppressed above the spin diffusion length in Cr, which is found to be 8 nm, and is independent of static exchange coupling in the spin valve. These results offer a valuable insight into the transmission and absorption of spin currents, and a mechanism by which enhanced spin torques and angular control may be realized for next-generation spintronic devices.

  17. Transient absorption of vibrationally excited water

    NASA Astrophysics Data System (ADS)

    Bakker, H. J.; Nienhuys, H.-K.; Gallot, G.; Lascoux, N.; Gale, G. M.; Leicknam, J.-C.; Bratos, S.

    2002-02-01

    We study the spectral response of the transition between the first and the second excited state of the O-H stretch vibration of HDO dissolved in liquid D2O with two-color femtosecond mid-infrared spectroscopy. The spectral response of this transition differs strongly from the fundamental absorption spectrum of the O-H stretch vibration. In addition, excitation of the O-H stretch vibration is observed to lead to a change of the hydrogen-bond dynamics of liquid water. We show that both these observations can be described with a refined quantum-mechanical version of the Lippincott-Schroeder model for hydrogen-bonded OH⋯O systems.

  18. Monitoring Telluric Water Absorption with CAMAL

    NASA Astrophysics Data System (ADS)

    Baker, Ashley; Blake, Cullen; Sliski, David

    2017-01-01

    Ground-based observations are severely limited by telluric water vapor absorption features, which are highly variable in time and significantly complicate both spectroscopy and photometry in the near-infrared (NIR). To achieve the stability required to study Earth-sized exoplanets, monitoring the precipitable water vapor (PWV) becomes necessary to mitigate the impact of telluric lines on radial velocity measurements and transit light curves. To address this issue, we present the Camera for the Automatic Monitoring of Atmospheric Lines (CAMAL), a stand-alone, inexpensive 6-inch aperture telescope dedicated to measuring PWV at the Whipple Observatory. CAMAL utilizes three NIR narrowband filters to trace the amount of atmospheric water vapor affecting simultaneous observations with the MINiature Exoplanet Radial Velocity Array (MINERVA) and MINERVA-Red telescopes. We present the current design of CAMAL, discuss our calibration methods, and show PWV measurements taken with CAMAL compared to those of a nearby GPS water vapor monitor.

  19. High Absorptance Coatings for THz Applications

    NASA Technical Reports Server (NTRS)

    Wollack, Edward J.

    2012-01-01

    High absorptance materials find application throughout the electromagnetic spectrum as radiation terminations, calibration standards, and glint reduction coatings. Successful use of materials at millimeter through submillimeter wavelengths requires an accurate knowledge and control over their thermal, mechanical, and electromagnetic properties in order to achieve the desired response while minimizing mass and volume. In practice, the achieved blackness is intimately linked to the material properties and geometry. Here, we summarize the characteristics of a variety of tunable artificial dielectric mixtures appropriate for THz applications at room and cryogenic temperatures. Theoretical guidelines for their application will be provided in the context of the effective-medium mean-field-approximation. The performance of these coatings as elements of reflectance standards, radiometric flux calibrators, passive thermal radiators, and stray light suppression baffles for imaging systems will be reviewed.

  20. Cavity Enhanced Ultrafast Transient Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Allison, Thomas K.; Reber, Melanie Roberts; Chen, Yuning

    2015-06-01

    Ultrafast spectroscopy on gas phase systems is typically restricted to techniques involving photoionization, whereas solution phase experiments utilize the detection of light. At Stony Brook, we are developing new techniques for performing femtosecond time-resolved spectroscopy using frequency combs and high-finesse optical resonators. A large detection sensitivity enhancement over traditional methods enables the extension of all-optical ultrafast spectroscopies, such as broad-band transient absorption spectroscopy (TAS) and 2D spectroscopy, to dilute gas phase samples produced in molecular beams. Here, gas phase data can be directly compared to solution phase data. Initial demonstration experiments are focusing on the photodissociation of iodine in small neutral argon clusters, where cluster size strongly influences the effects solvent-caging and geminate recombination. I will discuss these initial results, our high power home-built Yb:fiber laser systems, and also extensions of the methods to the mid-IR to study the vibrational dynamics of hydrogen bonded clusters.

  1. Optical absorption spectra of dications of carotenoids

    SciTech Connect

    Jeevarajan, J.A.; Wei, C.C.; Jeevarajan, A.S.; Kispert, L.D.

    1996-04-04

    Quantitative optical absorption spectra of the cation radicals and the dications of canthaxanthin (I), {beta}carotene (II), 7`-cyano-7`-ethoxycarbonyl-7`-apo-{beta}-carotene (III), and 7`,7`-dimethyl-7`-apo-{beta}-carotene (IV) in dichloromethane solution are reported. Exclusive formation of dications occurs when the carotenoids are oxidized with ferric chloride. Addition of neutral carotenoid to the dications results in equilibrium formation of cation radicals. Oxidation with iodine in dichloromethane affords only cation radicals; electrochemical oxidation under suitable conditions yields both dications and cation radicals. Values of the optical parameters depend on the nature of the oxidative medium. The oscillator strengths calculated for gas phase cation radicals and dications of I-IV using the INDO/S method show the same trend as the experimental values. 31 refs., 4 figs., 2 tabs.

  2. Intestinal absorption of calcium and phosphorus

    SciTech Connect

    Wasserman, R.H.

    1981-01-01

    The intestinal absorption of calcium and phosphorus has received considerable attention in recent years. The evidence has clearly indicated that calcium is absorbed by two processes: active transport and diffusion. Vitamin D appears to affect both processes, and has a significant effect at the brush border of the intestinal cell. Several proposed models to account for the transmural movement of calcium are discussed. The active transport of phosphate is under the control of vitamin D and is located at the brush border region of the intestinal cell. This transport system, like several others, appears to be sodium-dependent and inhibited by ouabain. In-transit phosphate does not mix with the cellular phosphate pool. Emphasized in the presentation is current knowledge of the transport mechanisms and macromolecular changes that potentially account for the stimulatory effect of vitamin D on calcium and phosphate transport.

  3. Spray generators for absorption refrigeration systems

    DOEpatents

    Sibley, Howard W.

    1979-06-19

    A spray generator for an absorption refrigeration system that includes a heat exchanger comprised of a multiplicity of variably spaced heat exchange tubes. The tubes are spaced close together near the top of the heat exchanger and spaced more widely apart near the bottom of the heat exchanger. Dilute absorbent solution is sprayed down through the heat exchanger. The close nesting of the tubes in the top portion of the heat exchanger retards liquid flow and aids heating of the solution. The wide spacing of the tubes in the lower section of the heat exchanger facilitate vapor flow out of the heat exchanger and eliminates liquid "blow-off". The top tubes are covered by a baffle to prevent the liquid solution from splashing out of the heat exchanger off of these top tubes.

  4. Statistics of cosmological Lyman α absorption

    NASA Astrophysics Data System (ADS)

    Munshi, Dipak; Coles, Peter; Viel, Matteo

    2012-12-01

    We study the effect of the non-Gaussianity induced by gravitational evolution upon the statistical properties of absorption in quasar (quasi-stellar object) spectra. Using the generic hierarchical ansatz and the lognormal approximation, we derive the analytical expressions for the one-point probability distribution function (PDF) as well as for the joint two-point PDF of transmitted fluxes in two neighbouring quasi-stellar objects. These flux PDFs are constructed in three dimensions as well as in projection (i.e. in two dimensions). The PDFs are constructed by relating the lower-order moments (i.e. cumulants and cumulant correlators) of the fluxes to the three-dimensional neutral hydrogen distribution, which is, in turn, expressed as a function of the underlying dark matter distribution. Next, the lower-order moments are modelled using a generating function formalism in the context of a minimal tree-model for the higher-order correlation hierarchy. These different approximations give nearly identical results for the range of redshifts probed, and we also find very good agreement between our predictions and the outputs of hydrodynamical simulations. The formalism developed here for the joint statistics of flux-decrements concerning two lines of sight can be extended to multiple lines of sight, which could be particularly important for the three-dimensional reconstruction of the cosmic web from the spectra of quasi-stellar objects (e.g. in the Baryon Oscillation Spectroscopic Survey). These statistics probe the underlying projected neutral hydrogen field and are thus linked to hotspots of absorption. The results for the PDF and the bias presented here use the same functional forms of scaling functions that have previously been employed for the modelling of other cosmological observations, such as the Sunyaev-Zel'dovich effect.

  5. Molecular absorption features in translucent clouds

    NASA Astrophysics Data System (ADS)

    Krelowski, Jacek

    2007-12-01

    Interstellar clouds, composed of neutral hydrogen, consist about 90% of the total mass of interstellar medium. Their absorption spectra contain: continuous extinction, atomic lines, molecular features and the unidentified diffuse interstellar bands (DIBs). The latter are also believed to be carried by some, rather complex molecules. A vast majority of DIBs is characterized by small central depths. This is why they became observable only since the solid state detectors are widely applied in astrophysics. It is to be emphasized that interstellar absorptions, seen along the same line of sight, may be in fact originated in several, different environments (clouds). The extensive database of echelle spectra allowed to prove that the CaII column density evidently correlates with parallaxes of OB-3 stars in contrast to other interstellar species. Thus CaII is quite evenly distributed in the interstellar medium while other species (NaI, KI, CaI, CH, CN, DIB carriers) are not. This fact is of basic importance as the ob- served spectra cannot be physically interpreted if they mix features originated in different clouds, i.e. in different environments. The abundance ratios of interstellar molecules (identified and DIB carriers) differ from cloud to cloud due to different physical processes which govern their formation. High resolution, high S/N spectra, prove that also profiles of diffuse bands vary from cloud to cloud - this fact strongly supports a molecular origin of these, still nidentified, features and motivates investigation of their relations to other molecules; they can reveal physical conditions which facilitate formation of the DIB carriers and lead to their identification.

  6. Impairment of ciprofloxacin absorption by calcium polycarbophil.

    PubMed

    Kato, Ryuji; Ueno, Kazuyuki; Imano, Hideki; Kawai, Masayuki; Kuwahara, Shiro; Tsuchishita, Yoshimasa; Yonezawa, Emi; Tanaka, Kazuhiko

    2002-07-01

    The effect of calcium polycarbophil on the absorption of ciprofloxacin, a broad-spectrum antibacterial agent, was evaluated in an in vitro and in vivo study. In the in vitro study, the release of ciprofloxacin from the cellulose membrane in the presence or absence of metal cations was measured using the dissolution test procedure. In the in vivo study, male ST Wistar rats and male volunteers were employed. First, 20 mg/kg of ciprofloxacin alone (Rat Study 1) or 20 mg/kg of ciprofloxacin in combination with 64 mg/kg of calcium chloride (Rat Study 2) was administered orally to 3 rats. Second, a volunteer study was employed and a randomized crossover design with twophases was used. In onephase, volunteers received 400 mg of ciprofloxacin alone (Study 1); in the other phase, they received 400 mg of ciprofloxacin and 1200 mg of fine calcium polycarbophil granules concomitantly (Study 2). The plasma and serum concentrations of ciprofloxacin were measured by high-performance liquid chromatography. The release of ciprofloxacin from the cellulose membrane in the presence of aluminum, calcium, or iron ions was slower than that in the absence of these metal ions. The AUC0-4 and Cmax in Rat Study 2 were lower than those respective values in Rat Study 1. AUC0-4 was approximately 60% lower in Rat Study 2 than Rat Study 1. In the volunteer study, the AUC0-12 and Cmax in Study 2 were lower than those respective values in Study 1. In particular, AUC0-12 was approximately 50% lowerin Study 2 than in Study 1. These findings suggest that when ciprofloxacin and calcium polycarbophil were coadministered concomitantly, a decrease of ciprofloxacin absorption was observed, and this action was caused by the formation of chelate complexes. Therefore, it seems clear that we should avoid the concomitant administration of ciprofloxacin and calcium polycarbophil.

  7. Atmospheric Measurements by Cavity Enhanced Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Yi, Hongming; Wu, Tao; Coeur-Tourneur, Cécile; Fertein, Eric; Gao, Xiaoming; Zhao, Weixiong; Zhang, Weijun; Chen, Weidong

    2015-04-01

    Since the last decade, atmospheric environmental monitoring has benefited from the development of novel spectroscopic measurement techniques owing to the significant breakthroughs in photonic technology from the UV to the infrared spectral domain [1]. In this presentation, we will overview our recent development and applications of cavity enhanced absorption spectroscopy techniques for in situ optical monitoring of chemically reactive atmospheric species (such as HONO, NO3, NO2, N2O5) in intensive campaigns [2] and/or in smog chamber studies [3]. These field deployments demonstrated that modern photonic technologies (newly emergent light sources combined with high sensitivity spectroscopic techniques) can provide a useful tool to improve our understanding of tropospheric chemical processes which affect climate, air quality, and the spread of pollution. Experimental detail and preliminary results will be presented. Acknowledgements. The financial support from the French Agence Nationale de la Recherche (ANR) under the NexCILAS (ANR-11-NS09-0002) and the CaPPA (ANR-10-LABX-005) contracts is acknowledged. References [1] X. Cui, C. Lengignon, T. Wu, W. Zhao, G. Wysocki, E. Fertein, C. Coeur, A. Cassez,L. Croisé, W. Chen, et al., "Photonic Sensing of the Atmosphere by absorption spectroscopy", J. Quant. Spectrosc. Rad. Transfer 113 (2012) 1300-1316 [2] T. Wu, Q. Zha, W. Chen, Z. XU, T. Wang, X. He, "Development and deployment of a cavity enhanced UV-LED spectrometer for measurements of atmospheric HONO and NO2 in Hong Kong", Atmos. Environ. 95 (2014) 544-551 [3] T. Wu, C. Coeur-Tourneur, G. Dhont,A. Cassez, E. Fertein, X. He, W. Chen,"Application of IBBCEAS to kinetic study of NO3 radical formation from O3 + NO2 reaction in an atmospheric simulation chamber", J. Quant. Spectrosc. Rad. Transfer 133 (2014)199-205

  8. Do proton pump inhibitors decrease calcium absorption?

    PubMed

    Hansen, Karen E; Jones, Andrea N; Lindstrom, Mary J; Davis, Lisa A; Ziegler, Toni E; Penniston, Kristina L; Alvig, Amy L; Shafer, Martin M

    2010-12-01

    Proton pump inhibitors (PPIs) increase osteoporotic fracture risk presumably via hypochlorhydria and consequent reduced fractional calcium absorption (FCA). Existing studies provide conflicting information regarding the direct effects of PPIs on FCA. We evaluated the effect of PPI therapy on FCA. We recruited women at least 5 years past menopause who were not taking acid suppressants. Participants underwent three 24-hour inpatient FCA studies using the dual stable isotope method. Two FCA studies were performed 1 month apart to establish baseline calcium absorption. The third study occurred after taking omeprazole (40 mg/day) for 30 days. Each participant consumed the same foods during all FCA studies; study meals replicated subjects' dietary habits based on 7-day diet diaries. Twenty-one postmenopausal women ages 58 ± 7 years (mean ± SD) completed all study visits. Seventeen women were white, and 2 each were black and Hispanic. FCA (mean ± SD) was 20% ± 10% at visit 1, 18% ± 10% at visit 2, and 23% ± 10% following 30 ± 3 days of daily omeprazole (p = .07, ANOVA). Multiple linear regression revealed that age, gastric pH, serum omeprazole levels, adherence to omeprazole, and 25-hydroxyvitamin D levels were unrelated to changes in FCA between study visits 2 and 3. The 1,25-dihydroxyvitamin D(3) level at visit 2 was the only variable (p = .049) associated with the change in FCA between visits 2 and 3. PPI-associated hypochlorhydria does not decrease FCA following 30 days of continuous use. Future studies should focus on identifying mechanisms by which PPIs increase the risk of osteoporotic fracture.

  9. Using Methane Absorption to Probe Jupiter's Atmosphere

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Mosaics of a belt-zone boundary near Jupiter's equator in near-infrared light moderately absorbed by atmospheric methane (top panel), and strongly absorbed by atmospheric methane (bottom panel). The four images that make up each of these mosaics were taken within a few minutes of each other. Methane in Jupiter's atmosphere absorbs light at specific wavelengths called absorption bands. By detecting light close and far from these absorption bands, Galileo can probe to different depths in Jupiter's atmosphere. Sunlight near 732 nanometers (top panel) is moderately absorbed by methane. Some of the light reflected from clouds deep in Jupiter's troposphere is absorbed, enhancing the higher features. Sunlight at 886 nanometers (bottom panel) is strongly absorbed by methane. Most of the light reflected from the deeper clouds is absorbed, making these clouds invisible. Features in the diffuse cloud layer higher in Jupiter's atmosphere are greatly enhanced.

    North is at the top. The mosaic covers latitudes -13 to +3 degrees and is centered at longitude 282 degrees West. The smallest resolved features are tens of kilometers in size. These images were taken on November 5th, 1996, at a range of 1.2 million kilometers by the Solid State Imaging system aboard NASA's Galileo spacecraft.

    The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo

  10. Regional differences in oxalate absorption by rat intestine: evidence for excessive absorption by the colon in steatorrhoea.

    PubMed Central

    Saunders, D R; Sillery, J; McDonald, G B

    1975-01-01

    Clinical studies suggest that steatorrhoea can be associated with excessive absorption of dietary oxalate. We examined the influence of bile salts, Ca++, and long-chain fatty acid on the absorption of oxalate and water by rat intestine in vivo. Absorption was measured under steady-state conditions during single-pass infusions. Each intestinal segment served as its own control. In jejunum, 10 mM taurocholate, the principal salt in rat bile, depressed absorption of oxalate and water. Absorption was not depressed further by Ca++ or linoleic acid. In ileum, 10 mM taurocholate did not inhibit absorption. Linoleic acid, 2 mM, depressed absorption of both oxalate and water. In colon 10 mM taurocholate decreased absorption. Net water transport was depressed further when linoleic acid was added to the infusion, but oxalate absorption was enhanced. Ca++ negated these effects of linoleic acid. It is concluded that long-chain fatty acids may enhance the absorption of oxalate from the rat colon. This observation may be relevant to understanding hyperoxaluria in patients with steatorrhoea. PMID:1158192

  11. The Early Universe Probed by QSO Absorption Lines

    NASA Astrophysics Data System (ADS)

    Misawa, Toru; Iye, Masanori

    2000-12-01

    High-z QSOs are valuable probes of the early universe and provide us information on the era of galaxy formation. QSOs can also be used as background sources against intervening objects such as proto-galactic clouds and faint foreground galaxies. These intervening objects produce absorption lines in the spectra of background QSOs. Gas clouds producing metal absorption lines are thought to exist in the halos of intervening galaxies and are used to evaluate the metal abundances of galaxies at high redshifts. In the course of studying the evolution of metal absorption lines, it was found that the number of absorbers per unit redshift interval increases in the vicinity of QSOs, especially of radio-loud QSOs. The reason of such an excess of metal absorption lines remains still unclear. In this paper, the authors review the absorption properties and enigmas of quasar absorption lines.

  12. Enhanced light absorption of solar cells and photodetectors by diffraction

    DOEpatents

    Zaidi, Saleem H.; Gee, James M.

    2005-02-22

    Enhanced light absorption of solar cells and photodetectors by diffraction is described. Triangular, rectangular, and blazed subwavelength periodic structures are shown to improve performance of solar cells. Surface reflection can be tailored for either broadband, or narrow-band spectral absorption. Enhanced absorption is achieved by efficient optical coupling into obliquely propagating transmitted diffraction orders. Subwavelength one-dimensional structures are designed for polarization-dependent, wavelength-selective absorption in solar cells and photodetectors, while two-dimensional structures are designed for polarization-independent, wavelength-selective absorption therein. Suitable one and two-dimensional subwavelength periodic structures can also be designed for broadband spectral absorption in solar cells and photodetectors. If reactive ion etching (RIE) processes are used to form the grating, RIE-induced surface damage in subwavelength structures can be repaired by forming junctions using ion implantation methods. RIE-induced surface damage can also be removed by post RIE wet-chemical etching treatments.

  13. Ultrafast transient absorption spectroscopy: principles and application to photosynthetic systems.

    PubMed

    Berera, Rudi; van Grondelle, Rienk; Kennis, John T M

    2009-01-01

    The photophysical and photochemical reactions, after light absorption by a photosynthetic pigment-protein complex, are among the fastest events in biology, taking place on timescales ranging from tens of femtoseconds to a few nanoseconds. The advent of ultrafast laser systems that produce pulses with femtosecond duration opened up a new area of research and enabled investigation of these photophysical and photochemical reactions in real time. Here, we provide a basic description of the ultrafast transient absorption technique, the laser and wavelength-conversion equipment, the transient absorption setup, and the collection of transient absorption data. Recent applications of ultrafast transient absorption spectroscopy on systems with increasing degree of complexity, from biomimetic light-harvesting systems to natural light-harvesting antennas, are presented. In particular, we will discuss, in this educational review, how a molecular understanding of the light-harvesting and photoprotective functions of carotenoids in photosynthesis is accomplished through the application of ultrafast transient absorption spectroscopy.

  14. Triple-band metamaterial absorption utilizing single rectangular hole

    NASA Astrophysics Data System (ADS)

    Kim, Seung Jik; Yoo, Young Joon; Kim, Young Ju; Lee, YoungPak

    2017-01-01

    In the general metamaterial absorber, the single absorption band is made by the single meta-pattern. Here, we introduce the triple-band metamaterial absorber only utilizing single rectangular hole. We also demonstrate the absorption mechanism of the triple absorption. The first absorption peak was caused by the fundamental magnetic resonance in the metallic part between rectangular holes. The second absorption was generated by induced tornado magnetic field. The process of realizing the second band is also presented. The third absorption was induced by the third-harmonic magnetic resonance in the metallic region between rectangular holes. In addition, the visible-range triple-band absorber was also realized by using similar but smaller single rectangular-hole structure. These results render the simple metamaterials for high frequency in large scale, which can be useful in the fabrication of metamaterials operating in the optical range.

  15. Vibrational resonance enhanced broadband multiphoton absorption in a triphenylamine derivative

    SciTech Connect

    Lu Changgui; Cui Yiping; Huang Wei; Yun Binfeng; Wang Zhuyuan; Hu Guohua; Cui Jing; Lu Zhifeng; Qian Ying

    2007-09-17

    Multiphoton absorption of 2,5-bis[4-(2-N,N-diphenylaminostyryl)phenyl]-1,3,4-oxadiazole was experimentally studied by using femtosecond laser pulses. This material demonstrates a very broad multiphoton absorption band of around 300 nm width with two peaks of 1250 and 1475 nm. The first peak results from the three-photon absorption process while the second is attributed to the vibrational resonance enhanced four-photon absorption process. Combination of these two processes provides a much broader multiphoton absorption band. In this letter, the analytical solution to nonlinear transmission of a three-photon absorption process is also given when the incident beam has a Gaussian transverse spatial profile.

  16. Absorption of Magnesium and Chloride by Excised Corn Root

    PubMed Central

    Maas, E. V.; Ogata, Gen

    1971-01-01

    Absorption characteristics of Mg2+ and Cl− were investigated with 5-day-old excised corn (Zea mays) roots. Uptake from both 0.5 and 10 milliequivalents per liter MgCl2 solutions occurred at steady state rates for the first 6 hours. Inhibition by dinitrophenol and low temperatures established that absorption during this period was metabolically mediated in the absence and presence of Ca2+. Absorption isotherms indicated dual mechanisms of Mg2+ and Cl− absorption from solutions above 1 milliequivalent per liter. The effect of H+ on absorption of Mg2+ and Cl− was typical of that generally reported for other plant roots and other ions. In the physiological pH range, Ca2+ greatly suppressed the rate of Mg2+ absorption but had little effect on Cl−. The influence of Ca2+ on Mg2+ appeared to be noncompetitive and independent of its effect on membrane permeability. PMID:16657622

  17. Absorption of magnesium and chloride by excised corn root.

    PubMed

    Maas, E V; Ogata, G

    1971-03-01

    Absorption characteristics of Mg(2+) and Cl(-) were investigated with 5-day-old excised corn (Zea mays) roots. Uptake from both 0.5 and 10 milliequivalents per liter MgCl(2) solutions occurred at steady state rates for the first 6 hours. Inhibition by dinitrophenol and low temperatures established that absorption during this period was metabolically mediated in the absence and presence of Ca(2+). Absorption isotherms indicated dual mechanisms of Mg(2+) and Cl(-) absorption from solutions above 1 milliequivalent per liter. The effect of H(+) on absorption of Mg(2+) and Cl(-) was typical of that generally reported for other plant roots and other ions. In the physiological pH range, Ca(2+) greatly suppressed the rate of Mg(2+) absorption but had little effect on Cl(-). The influence of Ca(2+) on Mg(2+) appeared to be noncompetitive and independent of its effect on membrane permeability.

  18. Performance Characteristics of Absorption Hybrid Cycle Introduced Compressor

    NASA Astrophysics Data System (ADS)

    Iyoki, Shigeki; Kotani, Yuji; Uemura, Tadashi

    In this paper, four kinds of absorption hybrid cycle which introduced the compressor in the absorption cycle were proposed. As basic cycle of absorption refrigerating machine, the following were chosen: two kinds of single-stage absorption refrigerating machine and two kinds of double effect absorption refrigerating machine. As a working medium-absorbent system, NH3-H2O system, C2H5NH2-H2O system and C2H5NH2-H2O-LiBr system were adopted. Using these three kinds of working medium-absorbent system, the performance characteristics of four kinds of absorption hybrid cycle were simulated. And the performance characteristics of these cycles were compared.

  19. Nitrogen-induced absorption of oxygen in the Herzberg continuum

    NASA Technical Reports Server (NTRS)

    Shardanand, MR.

    1977-01-01

    Total absorption of O2 induced by collisions with N2 has been measured at room temperature in the Hersberg continuum using a one meter normal incidence grating monochromator. The enhanced absorption is ascribed to the formation of O2-O2 and O2-N2 dimers. The interaction constants for these dimers are determined and utilized to investigate their effect on the absorption of solar radiation in the stratosphere.

  20. Blackbody absorption efficiencies for six lamp pumped Nd laser materials

    NASA Technical Reports Server (NTRS)

    Cross, Patricia L.; Barnes, Norman P.; Skolaut, Milton W., Jr.; Storm, Mark E.

    1990-01-01

    Utilizing high resolution spectra, the absorption efficiencies for six Nd laser materials were calculated as functions of the effective blackbody temperature of the lamp and laser crystal size. The six materials were Nd:YAG, Nd:YLF, Nd:Q-98 Glass, Nd:YVO4, Nd:BEL, and Nd:Cr:GSGG. Under the guidelines of this study, Nd:Cr:GSGG's absorption efficiency is twice the absorption efficiency of any of the other laser materials.

  1. Monitoring spacecraft atmosphere contaminants by laser absorption spectroscopy

    NASA Technical Reports Server (NTRS)

    Steinfeld, J. I.

    1975-01-01

    Data were obtained which will provide a test of the accuracy of the differential absorption method for trace contaminant detection in many-component gas mixtures. The necessary accurate absorption coefficient determinations were carried out for several gases; acetonitrile, 1,2-dichloroethane, Freon-113, furan, methyl ethyl ketone, and t-butyl alcohol. The absorption coefficients are displayed graphically. An opto-acoustic method was tested for measuring absorbance, similar to the system described by Dewey.

  2. A Lithium Bromide Absorption Chiller with Cold Storage

    DTIC Science & Technology

    2011-01-15

    TO R A G E A LITHIUM BROMIDE ABSORPTION CHILLER WITH COLD STORAGE William Gerstler, et al, General Electric Global Research UNCLASSIFIED UNLIMITED...Research ABSTRACT A LiBr-based absorption chiller can use waste heat or solar energy to produce useful space cooling for small buildings...However, operating this absorption chiller at high ambient tem- peratures may result in performance degradation, crystallization in the absorber, and

  3. Low-Absorption Liquid Crystals for Infrared Beam Steering

    DTIC Science & Technology

    2014-10-17

    goals are: ri~0.2 (at-tSilri),*? (at 1 kHz), and absorption coefficient B 5/cm. 15. SUBJECT TERMS Low absorption, MWIR, chlorinated liquid crystals...spectral region of interest by deuteration, fluorination and chlorination ; 2) Employing thin cell gap by choosing a high birefringence liquid crystal...mixture. First, we synthesized several chlorinated terphenyls and made a eutectic mixture showing a low absorption window in the region of 4-5|a.m

  4. Effect of idler absorption in pulsed optical parametric oscillators.

    PubMed

    Rustad, Gunnar; Arisholm, Gunnar; Farsund, Øystein

    2011-01-31

    Absorption at the idler wavelength in an optical parametric oscillator (OPO) is often considered detrimental. We show through simulations that pulsed OPOs with significant idler absorption can perform better than OPOs with low idler absorption both in terms of conversion efficiency and beam quality. The main reason for this is reduced back conversion. We also show how the beam quality depends on the beam width and pump pulse length, and present scaling relations to use the example simulations for other pulsed nanosecond OPOs.

  5. Ultraviolet interstellar absorption lines from low-z galaxies

    NASA Astrophysics Data System (ADS)

    Sahu, M. S.

    1997-05-01

    The importance of studying absorption lines from z<<0.1 galaxies are discussed. The Mg II λλ2796 and 2803 Å doublet absorption is sensitive to low column density gas and has been used to search for absorption lines from low-z galaxies. Recent studies of abundances and depletion patterns toward the Small Magellanic Cloud (Welty et al. 1997) and the NGC 1705 sightline (Sahu & Blades, 1997) are reviewed.

  6. Coherent perfect absorption and reflection in slow-light waveguides.

    PubMed

    Gutman, Nadav; Sukhorukov, Andrey A; Chong, Y D; de Sterke, C Martijn

    2013-12-01

    We identify a family of unusual slow-light modes occurring in lossy multimode grating waveguides, for which either the forward or backward mode components, or both, are degenerate. In the fully degenerate case, the response can be modulated between coherent perfect absorption (zero reflection) and perfect reflection by varying the wave amplitudes in a uniform input waveguide. The perfectly absorbed wave has anomalously short absorption length, scaling as the inverse one-third power of the absorptivity.

  7. Calculation of laser absorption by metal powders in additive manufacturing.

    PubMed

    Boley, C D; Khairallah, S A; Rubenchik, A M

    2015-03-20

    We have calculated the absorption of laser light by a powder of metal spheres, typical of the powder employed in laser powder-bed fusion additive manufacturing. Using ray-trace simulations, we show that the absorption is significantly larger than its value for normal incidence on a flat surface, due to multiple scattering. We investigate the dependence of absorption on powder content (material, size distribution, and geometry) and on beam size.

  8. Flameless Atomic Absorption Spectrophotometric Analysis for Lewisite (L).

    DTIC Science & Technology

    1978-10-01

    method that was developed for detection of Lewisite by analysis for arsenic, using flameless atomic absorption spectroscopy (FAAS). “Flameless atomic ...place in a furnace, and the flame associated with con- ventional atomic absorption spectroscopy is not needed. The procedure that was used is given along...nickel was unnecessary for the Lewisite samples. Table 1. Flameless atomic absorption spectroscopy conditions used for determination of arsenic in

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

    SciTech Connect

    Jefferson, Anne

    2014-05-01

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

  10. Perfect electromagnetic absorption at one-atom-thick scale

    SciTech Connect

    Li, Sucheng; Duan, Qian; Li, Shuo; Yin, Qiang; Lu, Weixin; Li, Liang; Hou, Bo; Gu, Bangming; Wen, Weijia

    2015-11-02

    We experimentally demonstrate that perfect electromagnetic absorption can be realized in the one-atom thick graphene. Employing coherent illumination in the waveguide system, the absorbance of the unpatterned graphene monolayer is observed to be greater than 94% over the microwave X-band, 7–13 GHz, and to achieve a full absorption, >99% in experiment, at ∼8.3 GHz. In addition, the absorption characteristic manifests equivalently a wide range of incident angle. The experimental results agree very well with the theoretical calculations. Our work accomplishes the broadband, wide-angle, high-performance absorption in the thinnest material with simple configuration.

  11. Anomalous absorption in CO2-laser-target interactions

    NASA Astrophysics Data System (ADS)

    Offenberger, A. A.; Ng, A.

    1980-10-01

    Efficient absorption of long-pulse CO2-laser radiation is observed to follow a transient phase of stimulated Brillouin backscatter in critical density, laminar oxygen gas target irradiation experiments. Nearly complete energy absorption occurs for not more than 10 nsec following stimulated Brillouin backscatter after which target burnthrough and refraction dominate. Inverse bremsstrahlung and resonance absorption cannot account for the general features observed. Anomalous collisions due to strong ion turbulence produced by the incident laser radiation are postulated to account for the efficient absorption.

  12. Temporal evolutional absorption behaviors of graphene under Landau quantization

    NASA Astrophysics Data System (ADS)

    Hamedi, H. R.; Sahrai, M.

    2017-02-01

    We investigate the evolutional absorption behaviors of Landau-quantized graphene structure based on the transient solution to the density matrix equations of the motion. The impact of various system parameters on temporal evolution of probe absorption is studied. In addition, the required times for switching the high-absorption case to the zero-absorption (transparency) of a probe field is discussed. Due to unusual optical and electronic characteristics of graphene resulting from linear, massless dispersion of electrons near the Dirac point and the chiral character of electron states, our study may have potential applications in telecommunication, biomedicine, and optical information processing and may cause significant impact on technological applications.

  13. Absorption spectrum of DNA for wavelengths greater than 300 nm

    SciTech Connect

    Sutherland, J.C.; Griffin, K.P.

    1981-06-01

    Although DNA absorption at wavelengths greater than 300 nm is much weaker than that at shorter wavelengths, this absorption seems to be responsible for much of the biological damage caused by solar radiation of wavelengths less than 320 nm. Accurate measurement of the absorption spectrum of DNA above 300 nm is complicated by turbidity characteristic of concentrated solutions of DNA. We have measured the absorption spectra of DNA from calf thymus, Clostridium perfringens, Escherichia coli, Micrococcus luteus, salmon testis, and human placenta using procedures which separate optical density due to true absorption from that due to turbidity. Above 300 nm, the relative absorption of DNA increases as a function of guanine-cytosine content, presumably because the absorption of guanine is much greater than the absorption of adenine at these wavelengths. This result suggests that the photophysical processes which follow absorption of a long-wavelength photon may, on the average, differ from those induced by shorter-wavelength photons. It may also explain the lower quantum yield for the killing of cells by wavelengths above 300 nm compared to that by shorter wavelengths.

  14. CO2 Capture from Flue Gas by Phase Transitional Absorption

    SciTech Connect

    Liang Hu

    2009-06-30

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

  15. Beta Absorption Mass Monitoring of Particulates - A Review

    NASA Technical Reports Server (NTRS)

    Lilienfeld, Pedro

    1971-01-01

    The theory and application of beta-radiation absorption for the measurement and monitoring of airborne particulates are discussed. The use of this technique, both for source testing and for ambient air quality monitoring is reviewed. Various particle collection methods used in conjunction with beta absorption sensing configurations are considered. State of the art and current developments of instrumentation approaches for the automated measurement of mass concentration and size distribution of aerosols by beta absorption are discussed. Methods for electronic signal processing and recording are presented. The Beta absorption technique appears as a powerful tool for the unattended measurement of the mass of particulate pollution, compatible with telemetry and central data processing methods.

  16. Energy absorption of refractory absorber with periodic nanostructures

    NASA Astrophysics Data System (ADS)

    Kang, Yuchen; Yang, Shuhan; Wang, Yanhong; Wu, Jingzhi

    2016-10-01

    Refractory material with surface plasmonic structures have the function of spectrum selective absorption and radiation spectrum regulation. In this paper, we design an absorber with periodic cylindrical nanostructures and a dielectric layer of Al2O3 based on the substrate of metal Tantalum (Ta). The energy absorption characteristics of the absorber have been simulated and analyzed by changing various constructional parameters. The simulation results indicate that structural parameters have great influence on the spectrum absorption in the range of wavelength 400-4000nm. The period and radius of nanostructure have a important effect on the absorption peaks in the infrared region. Infrared absorption peak can reach more than 99% and produce a red shift due to parameters changing. At the whole visible field, the absorption enhancement effect is significant. The refractive index and thickness of dielectric layer also have an obviously effect on the absorption spectrum. Furthermore, it is also obviously that thickness of dielectric layer has enhancement effect on absorption of infrared spectrum. The research found that the absorption and radiation spectrum of surface plasmonic materials can be effectively controlled by combining the high temperature radiation characteristics of high temperature metal. Thermophotovoltaic system can provide a kind of new methods and ideas for improving conversion efficiency, energy saving and consumption reducing.

  17. Absorption-Desorption Compressor for Spaceborne/Airborne Cryogenic Refrigerators.

    DTIC Science & Technology

    Refrigerant compressors, *Refrigeration systems), Spaceborne, Airborne, Cryogenics, Gases, Absorption, Desorption, Hydrogen, Hydrides, Lanthanum compounds, Nickel alloys, Joule Thomson effect , Heat transfer

  18. Sapphire fiber evanescent wave absorption in turbid media.

    PubMed

    Zhang, Jian; Xiong, Feibing; Djeu, Nicholas

    2009-08-01

    The influence of particulates on sapphire fiber evanescent wave absorption by water has been studied. Suspensions containing micro-sized graphite flakes and glassy carbon powder were used. Conventional free-space transmittance measurements of these samples showed strong absorption and scattering, which severely screened the absorption by water. However, the absorption on the water band determined from the evanescent wave interaction was unaffected by the presence of the graphite flakes. These results indicate that fiber-optic evanescent wave chemical sensors may be suitable for process control applications involving turbid reactor streams.

  19. Solar assisted gas-fired absorption heat pump

    NASA Astrophysics Data System (ADS)

    Murphy, K. P.; Burke, J. C.; Phillips, B. A.

    1982-08-01

    An evaluation of the technical and economic feasibility of coupling an absorption heat pump and an active solar system for residential applications is discussed. The absorption heat pump is based on a new absorption working pair developed by Allied. Three basic modes of coupling were considered, a series arrangement, a parallel arrangement, and a solar drive arrangement. Little overall difference in performance was found for these three modes but the solar drive was chosen for detailed study. A preliminary design of a dual mode absorption generator was developed capable of using simultaneously heat from gas and solar. The performance of such a system was examined in three cities.

  20. Thomson Thick X-Ray Absorption in a Broad Absorption Line Quasar, PG 0946+301.

    PubMed

    Mathur; Green; Arav; Brotherton; Crenshaw; deKool; Elvis; Goodrich; Hamann; Hines; Kashyap; Korista; Peterson; Shields; Shlosman; van Breugel W; Voit

    2000-04-20

    We present a deep ASCA observation of a broad absorption line quasar (BALQSO) PG 0946+301. The source was clearly detected in one of the gas imaging spectrometers, but not in any other detector. If BALQSOs have intrinsic X-ray spectra similar to normal radio-quiet quasars, our observations imply that there is Thomson thick X-ray absorption (NH greater, similar1024 cm-2) toward PG 0946+301. This is the largest column density estimated so far toward a BALQSO. The absorber must be at least partially ionized and may be responsible for attenuation in the optical and UV. If the Thomson optical depth toward BALQSOs is close to 1, as inferred here, then spectroscopy in hard X-rays with large telescopes like XMM would be feasible.

  1. Vertical transition energies vs. absorption maxima: illustration with the UV absorption spectrum of ethylene.

    PubMed

    Lasorne, Benjamin; Jornet-Somoza, Joaquim; Meyer, Hans-Dieter; Lauvergnat, David; Robb, Michael A; Gatti, Fabien

    2014-02-05

    We revisit the validity of making a direct comparison between measured absorption maxima and computed vertical transition energies within 0.1 eV to calibrate an excited-state level of theory. This is illustrated on the UV absorption spectrum of ethylene for which the usual experimental values of 7.66 eV (V←N) and 7.11 eV (R(3s)←N) cannot be compared directly to the results of electronic structure calculations for two very different reasons. After validation of our level of theory against experimental data, a new experimental reference of 7.28 eV is suggested for benchmarking the Rydberg state, and the often-cited average transition energy (7.80 eV) is confirmed as a safer estimate for the valence state.

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

    SciTech Connect

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

    1987-01-01

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

  3. Delta bilirubin: absorption spectra, molar absorptivity, and reactivity in the diazo reaction.

    PubMed

    Doumas, B T; Wu, T W; Jendrzejczak, B

    1987-06-01

    Delta bilirubin (B delta), isolated from serum, has an absorption maximum near 440 nm and a molar absorptivity of 72,000 L mol-1cm-1 in either Tris HCl (0.1 mol/L, pH 8.5) or phosphate (0.13 mol/L, pH 7.4) buffer. This absorptivity exceeds by approximately 50% and 59%, respectively, that of unconjugated bilirubin in the same buffers. This finding suggests that substantial errors can be incurred in direct spectrophotometry of bilirubins in serum. In the total diazo (TBIL) assay (Clin Chem 1985;31:1779-89), the color yield from B delta increases by 10% as the final diazo concentration is increased from 0.27 to 0.81 mmol/L. In the direct (DBIL) assay, if done in HCl (50 mmol/L), B delta yields approximately 15% more color as the diazo concentration is increased from 0.51 to 1.53 mmol/L, whereas in acetate buffer (0.4 mol/L, pH 4.7) the corresponding color yield is 25% greater. However, the absolute color yield for the reaction in HCl exceeds that in acetate buffer. In both the TBIL and the DBIL assay, B delta reacts slowly, nearly complete reaction requiring 10 min. Thus, B delta may be seriously underestimated in diazo (especially DBIL) methods in which short reaction times (20 s to 1 min) are used.

  4. Studies of OH - absorption and optical absorption spectra in LiNbO 3 : Mg, Ti crystals

    NASA Astrophysics Data System (ADS)

    Liu, Jianjun; Zhang, Wanlin; Zhang, Guangyin

    1996-02-01

    The OH - absorption spectra and the UV absorption edges of LiNbO 3 : Mg, Ti crystals have been measured. It is shown that Ti doping raises the Mg doping threshold level, and shifts the absorption edge towards longer wavelengths. The results can be explained by the formation of Mg Li2+Ti Nb4+ pairs after all antisite defects Nb Li have been replaced.

  5. Unusual continuous dual absorption peaks in Ca-doped BiFeO3 nanostructures for broadened microwave absorption

    NASA Astrophysics Data System (ADS)

    Li, Zhong-Jun; Hou, Zhi-Ling; Song, Wei-Li; Liu, Xing-Da; Cao, Wen-Qiang; Shao, Xiao-Hong; Cao, Mao-Sheng

    2016-05-01

    Electromagnetic absorption materials have received increasing attention owing to their wide applications in aerospace, communication and the electronics industry, and multiferroic materials with both polarization and magnetic properties are considered promising ceramics for microwave absorption application. However, the insufficient absorption intensity coupled with the narrow effective absorption bandwidth has limited the development of high-performance multiferroic materials for practical microwave absorption. To address such issues, in the present work, we utilize interfacial engineering in BiFeO3 nanoparticles via Ca doping, with the purpose of tailoring the phase boundary. Upon Ca-substitution, the co-existence of both R3c and P4mm phases has been confirmed to massively enhance both dielectric and magnetic properties via manipulating the phase boundary and the destruction of the spiral spin structure. Unlike the commonly reported magnetic/dielectric hybrid microwave absorption composites, Bi0.95Ca0.05FeO3 has been found to deliver unusual continuous dual absorption peaks at a small thickness (1.56 mm), which has remarkably broadened the effective absorption bandwidth (8.7-12.1 GHz). The fundamental mechanisms based on the phase boundary engineering have been discussed, suggesting a novel platform for designing advanced multiferroic materials with wide applications.Electromagnetic absorption materials have received increasing attention owing to their wide applications in aerospace, communication and the electronics industry, and multiferroic materials with both polarization and magnetic properties are considered promising ceramics for microwave absorption application. However, the insufficient absorption intensity coupled with the narrow effective absorption bandwidth has limited the development of high-performance multiferroic materials for practical microwave absorption. To address such issues, in the present work, we utilize interfacial engineering in BiFeO3

  6. Remote Sensing of Aerosol and Non-Aerosol Absorption

    NASA Technical Reports Server (NTRS)

    Kaufman, Y. J.; Dubovik, O.; Holben, B. N.; Remer, L. A.; Tanre, D.; Lau, William K. M. (Technical Monitor)

    2001-01-01

    Remote sensing of aerosol from the new satellite instruments (e.g. MODIS from Terra) and ground based radiometers (e.g. the AERONET) provides the opportunity to measure the absorption characteristics of the ambient undisturbed aerosol in the entire atmospheric column. For example Landsat and AERONET data are used to measure spectral absorption of sunlight by dust from West Africa. Both Application of the Landsat and AERONET data demonstrate that Saharan dust absorption of solar radiation is several times smaller than the current international standards. This is due to difficulties of measuring dust absorption in situ, and due to the often contamination of dust properties by the presence of air pollution or smoke. We use the remotely sensed aerosol absorption properties described by the spectral sin le scattering albedo, together with statistics of the monthly optical thickness for the fine and coarse aerosol derived from the MODIS data. The result is an estimate of the flux of solar radiation absorbed by the aerosol layer in different regions around the globe where aerosol is prevalent. If this aerosol forcing through absorption is not included in global circulation models, it may be interpreted as anomalous absorption in these regions. In a preliminary exercise we also use the absorption measurements by AERONET, to derive the non-aerosol absorption of the atmosphere in cloud free conditions. The results are obtained for the atmospheric windows: 0.44 microns, 0.66 microns, 0.86 microns and 1.05 microns. In all the locations over the land and ocean that were tested no anomalous absorption in these wavelengths, was found within absorption optical thickness of +/- 0.005.

  7. Light absorption by organic carbon from wood combustion

    NASA Astrophysics Data System (ADS)

    Chen, Y.; Bond, T. C.

    2010-02-01

    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 surfaces.

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

    PubMed

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

    2014-01-14

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

  9. Vehicle effects on human stratum corneum absorption and skin penetration.

    PubMed

    Zhang, Alissa; Jung, Eui-Chang; Zhu, Hanjiang; Zou, Ying; Hui, Xiaoying; Maibach, Howard

    2016-07-19

    This study evaluated the effects of three vehicles-ethanol (EtOH), isopropyl alcohol (IPA), and isopropyl myristate (IPM)-on stratum corneum (SC) absorption and diffusion of the [(14)C]-model compounds benzoic acid and butenafine hydrochloride to better understand the transport pathways of chemicals passing through and resident in SC. Following application of topical formulations to human dermatomed skin for 30 min, penetration flux was observed for 24 h post dosing, using an in vitro flow-through skin diffusion system. Skin absorption and penetration was compared to the chemical-SC (intact, delipidized, or SC lipid film) binding levels. A significant vehicle effect was observed for chemical skin penetration and SC absorption. IPA resulted in the greatest levels of intact SC/SC lipid absorption, skin penetration, and total skin absorption/penetration of benzoic acid, followed by IPM and EtOH, respectively. For intact SC absorption and total skin absorption/penetration of butenafine, the vehicle that demonstrated the highest level of sorption/penetration was EtOH, followed by IPA and IPM, respectively. The percent doses of butenafine that were absorbed in SC lipid film and penetrated through skin in 24 h were greatest for IPA, followed by EtOH and IPM, respectively. The vehicle effect was consistent between intact SC absorption and total chemical skin absorption and penetration, as well as SC lipid absorption and chemical penetration through skin, suggesting intercellular transport as a main pathway of skin penetration for model chemicals. These results suggest the potential to predict vehicle effects on skin permeability with simple SC absorption assays. As decontamination was applied 30 min after chemical exposure, significant vehicle effects on chemical SC partitioning and percutaneous penetration also suggest that skin decontamination efficiency is vehicle dependent, and an effective decontamination method should act on chemical solutes in the lipid domain.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  11. Absorption media for irreversibly gettering thionyl chloride

    DOEpatents

    Buffleben, George; Goods, Steven H.; Shepodd, Timothy; Wheeler, David R.; Whinnery, Jr., LeRoy

    2002-01-01

    Thionyl chloride is a hazardous and reactive chemical used as the liquid cathode in commercial primary batteries. Contrary to previous thinking, ASZM-TEDA.RTM. carbon (Calgon Corporation) reversibly absorbs thionyl chloride. Thus, several candidate materials were examined as irreversible getters for thionyl chloride. The capacity, rate and effect of temperature were also explored. A wide variety of likely materials were investigated through screening experiments focusing on the degree of heat generated by the reaction as well as the material absorption capacity and irreversibility, in order to help narrow the group of possible getter choices. More thorough, quantitative measurements were performed on promising materials. The best performing getter was a mixture of ZnO and ASZM-TEDA.RTM. carbon. In this example, the ZnO reacts with thionyl chloride to form ZnCl.sub.2 and SO.sub.2. The SO.sub.2 is then irreversibly gettered by ASZM-TEDA.RTM. carbon. This combination of ZnO and carbon has a high capacity, is irreversible and functions effectively above -20.degree. C.

  12. Cost reduction in absorption chillers: Phase 2

    SciTech Connect

    Leigh, R.W.

    1989-02-01

    A research program at Brookhaven National Laboratory (BNL) has addressed the possibility of dramatically lowering the first costs of absorption chillers through lowered material intensity and the use of lower cost materials, primarily in the heat exchangers which make up the bulk of the operating components of these systems. This must be done while retaining the best performance characteristics available today, a gross design point coefficient of performance (COP) of 1.3 and a net design (seasonal) average COP of 1.0 (0.90) in a directly fired, double effect unit. We have investigated several possible routes to these goals, and here report on these findings, focusing on the areas that appear most promising. The candidate technologies include the use of polymer film heat exchangers in several applications, the use of thin strips of new, corrosion resistant alloys to replace thicker, less impervious metals in applications exposed to gas flames, and copper or cupro-nickel foils in contact with system water. The use of such materials is only possible in the context of new heat exchanger and system designs, which are also discussed. To lend focus, we have concentrated on a directly fired double effect system providing capacity only. If successful, these techniques will also find wide applicability in heat pumps, cogeneration systems, solar cooling, heat recovery and chemical process heat transfer. 46 refs., 24 figs., 22 tabs.

  13. Permeation absorption sampler with multiple detection

    DOEpatents

    Zaromb, Solomon

    1990-01-01

    A system for detecting analytes in air or aqueous systems includes a permeation absorption preconcentrator sampler for the analytes and analyte detectors. The preconcentrator has an inner fluid-permeable container into which a charge of analyte-sorbing liquid is intermittently injected, and a fluid-impermeable outer container. The sample is passed through the outer container and around the inner container for trapping and preconcentrating the analyte in the sorbing liquid. The analyte can be detected photometrically by injecting with the sorbing material a reagent which reacts with the analyte to produce a characteristic color or fluorescence which is detected by illuminating the contents of the inner container with a light source and measuring the absorbed or emitted light, or by producing a characteristic chemiluminescence which can be detected by a suitable light sensor. The analyte can also be detected amperometrically. Multiple inner containers may be provided into which a plurality of sorbing liquids are respectively introduced for simultaneously detecting different analytes. Baffles may be provided in the outer container. A calibration technique is disclosed.

  14. Absorption of harmonic light in plasmonic nanostructures

    NASA Astrophysics Data System (ADS)

    Vincenti, Maria A.; de Ceglia, Domenico; Scalora, Michael

    2016-09-01

    Surface plasmons are known for their ability to provide large field enhancement at the interface between a metal and another medium. They can be observed in a variety of structures ranging from plain metallic films to nanoparticles and gratings. Thanks to their large electric field enhancement, surface plasmons have also been exploited for the enhancement of second and third harmonic generation. In fact, metals possess a relatively high third order susceptibility and, although dipole-allowed quadratic nonlinearities are not present in the bulk, they also display an effective second order response that arises from symmetry breaking at the surface, magnetic dipoles (Lorentz force), inner-core electrons, convective nonlinear sources, and electron gas pressure. While much attention has been devoted to achieve efficient excitation of surface plasmons to improve far-field harmonic generation, little or no attention has been paid to the dissipation of the generated harmonic light. Therefore, we undertake a discussion of both harmonic generation and absorption in simple metallic/dielectric interfaces with or without excitation of surface plasmons. We demonstrate that, despite the best efforts embarked upon to study plasmon excitation, the absorbed harmonic energy can far surpass the energy emitted in the far-field. These findings suggest that quantification of the absorbed harmonic light should be an important parameter in evaluating designs of plasmonic nanostructures for frequency mixing.

  15. Sound absorption in nonelectrolyte aqueous solutions

    NASA Astrophysics Data System (ADS)

    Endo, Harumi; Honda, Kazuyuki

    2001-10-01

    We indicate that the curve fitting for Debye-type relaxation spectrum of sound absorption (SA) cannot sufficiently account for the observed data of nonelectrolyte aqueous solutions (NEAS). To solve these problems, we introduce the distribution function of relaxation time [DFRT, F(τ)] from a diffusion equation of concentration fluctuations using the fluctuation dispersion theory. The SA expression is described by four-adjustable parameters. By use of the mixtures of 1-propanol, t-butanol, and monobutyl triethylene glycol with water, our calculation of SA shows the best fit between the observed and calculated curves, compared with other models. It was found that at lower frequencies the SA behaves as the square root of frequency. The approximate expression of DFRT was expressed in terms of a power law of relaxation time, F(τ)∝τ-γ, which is the same as the expression of dielectric relaxation by Matsumoto and Higashi. Our exponent (γ) of relaxation time is varied from 5/2 in hydrophilic solutes to 3/2 in hydrophobic solutes. The power (γ) of relaxation time was regarded as a parameter to explain the hydrophobic and hydrophilic in the dissolved states of a solute. Our SA expression of γ=5/2 for solutes of a small correlation length leads to that of Romanov-Solov'ev, where the value of 5/2 is that of the Debye distribution for the relaxation time in the Romanov-Solov'ev model.

  16. Subwavelength single layer absorption resonance antireflection coatings.

    PubMed

    Huber, S P; van de Kruijs, R W E; Yakshin, A E; Zoethout, E; Boller, K-J; Bijkerk, F

    2014-01-13

    We present theoretically derived design rules for an absorbing resonance antireflection coating for the spectral range of 100 - 400 nm, applied here on top of a molybdenum-silicon multilayer mirror (Mo/Si MLM) as commonly used in extreme ultraviolet lithography. The design rules for optimal suppression are found to be strongly dependent on the thickness and optical constants of the coating. For wavelengths below λ ∼ 230 nm, absorbing thin films can be used to generate an additional phase shift and complement the propagational phase shift, enabling full suppression already with film thicknesses far below the quarter-wave limit. Above λ ∼ 230 nm, minimal absorption (k < 0.2) is necessary for low reflectance and the minimum required layer thickness increases with increasing wavelength slowly converging towards the quarter-wave limit.As a proof of principle, SixCyNz thin films were deposited that exhibit optical constants close to the design rules for suppression around 285 nm. The thin films were deposited by electron beam co-deposition of silicon and carbon, with N+ ion implantation during growth and analyzed with variable angle spectroscopic ellipsometry to characterize the optical constants. We report a reduction of reflectance at λ = 285 nm, from 58% to 0.3% for a Mo/Si MLM coated with a 20 nm thin film of Si0.52C0.16N0.29.

  17. Quantification of D-region Absorption

    NASA Astrophysics Data System (ADS)

    Langston, J. S.; Moore, R. C.

    2012-12-01

    An HF cross-modulation technique is employed to probe the D-region ionosphere during modulated HF heating experiments at the High-frequency Active Auroral Research Program (HAARP) observatory. The presented method is a modified version of the more typical pulse-modulated HF cross-modulation experiments during which the ionosphere is heated with a high-power pulsed wave and a second pulsed wave is transmitted at a low-power to probe the modulated D-region. During the modulated heating experiments discussed herein, the high-power wave is instead either an amplitude modulated (AM) wave or continuous wave (CW). It has long since been established that careful measurements of the amplitude and phase of a pulse cross-modulated signal may be used to quantify the ambient and modified characteristics of the D-region ionosphere (e.g. quantifying the ambient and modified D-region conductivity), but with this new transmission, the change in absorption and phase of the low-power pulsed wave can be quantified as a function of modulation duration up to steady-state. This experiment was performed for different heating power levels, different HF frequencies, and different heating waveforms (sinusoidal, square wave, and continuous wave). Experiments were performed at HAARP in September 2011 (two pulse experiment) and February 2012 (three pulse experiment).

  18. Ultraviolet-Absorption Spectroscopic Biofilm Monitor

    NASA Technical Reports Server (NTRS)

    Micheels, Ronald H.

    2004-01-01

    An ultraviolet-absorption spectrometer system has been developed as a prototype instrument to be used in continuous, real-time monitoring to detect the growth of biofilms. Such monitoring is desirable because biofilms are often harmful. For example, biofilms in potable-water and hydroponic systems act as both sources of pathogenic bacteria that resist biocides and as a mechanism for deterioration (including corrosion) of pipes. Biofilms formed from several types of hazardous bacteria can thrive in both plant-growth solutions and low-nutrient media like distilled water. Biofilms can also form in condensate tanks in air-conditioning systems and in industrial heat exchangers. At present, bacteria in potable-water and plant-growth systems aboard the space shuttle (and previously on the Mir space station) are monitored by culture-plate counting, which entails an incubation period of 24 to 48 hours for each sample. At present, there are no commercially available instruments for continuous monitoring of biofilms in terrestrial or spaceborne settings.

  19. Interstellar Medium Absorption Profile Spectrograph (IMAPS)

    NASA Technical Reports Server (NTRS)

    Jenkins, E. B.

    1985-01-01

    The design and fabrication of an objective-grating echelle spectrograph to fly on sounding rockets and record spectra of stars from approximately 920 to 1120A with a resolving power lambda/delta lambda = 200,000 is discussed. The scientific purpose of the program is to observe, with ten times better velocity resolution than before, the plentiful absorption lines in this spectral region produced by atoms, ions and molecules in the interstellar medium. In addition, an important technical goal is to develop and flight-quality a new ultraviolet, photon-counting image sensor which has a windowless, opaque photocathode and a CCD bombarded directly by the accelerated photoelectrons. Except for some initial difficulties with the performance of CCDs, the development of the payload instrument is relatively straightforward and our overall design goals are satisfied. The first flight occurred in late 1984, but no data were obtained because of an inrush of air degraded the instrument's vacuum and caused the detector's high voltage to arc. A second flight in early 1985 was a complete success and obtained a spectrum of pi Sco. Data from this mission are currently being reduced; quick-look versions of the spectra indicate that excellent results will be obtained. Currently, the payload is being reconfigured to fly on a Spartan mission in 1988.

  20. Regulation of Iron Absorption in Hemoglobinopathies

    PubMed Central

    Rechavi, Gideon; Rivella, Stefano

    2013-01-01

    Beta-thalassemia and sickle cell anemia (SCD) represent the most common hemoglobinopathies caused, respectively, by deficient production or alteration of the beta chain of hemoglobin (Hb). Patients affected by the most severe form of thalassemia suffer from profound anemia that requires chronic blood transfusions and chelation therapies to prevent iron overload. However, patients affected by beta-thalassemia intermedia, a milder form of the disease that does not require chronic blood transfusions, eventually also show elevated body iron content due to increased gastrointestinal iron absorption. Even SCD patients might require blood transfusions and iron chelation to prevent deleterious and painful vaso-occlusive crises and complications due to iron overload. Although definitive cures are presently available, such as bone marrow transplantation (BMT), or are in development, such as correction of the disease through hematopoietic stem cell beta-globin gene transfer, they are potentially hazardous procedures or too experimental to provide consistently safe and predictive clinical outcomes. Therefore, studies that aim to better understand the pathophysiology of the hemoglobinopathies might provide further insight and new drugs to dramatically improve the understanding and current treatment of these diseases. This review will describe how recent discoveries on iron metabolism and erythropoiesis could lead to new therapeutic strategies and better clinical care of these diseases, thereby yielding a much better quality of life for the patients. PMID:18991651

  1. Effect of folic acid on zinc absorption

    SciTech Connect

    Wada, L.; Keating, S.; King, J.C.; Stokstad, E.L.R.

    1986-03-05

    The effect of folic acid on zinc uptake was studied in the human and in the rat. The serum zinc response to a 25 mg oral dose or zinc was measured with and without a 10 mg dose of folic acid. Serum zinc levels were measured prior to the oral dose of zinc and at hourly intervals up to 4 hours after the dose. When zinc was given along, the increases in serum zinc from baseline at hours 1, 2, 3 and 4 were 92, 118, 92 and 66 ..mu..g/dl, respectively. When both zinc and folic acid were given, the increases in serum zinc at hours 1, 2, 3 and 4 were 100, 140, 110 and 75 ..mu..g/dl, respectively. When the increases in serum zinc were plotted against time, there was no significant difference between the areas under the two curves. The everted jejunal sac from the rat was used to study the effect of folate on zinc transport using 100 ..mu..M zinc in the mucosal buffer. The addition of folic acid at levels up to 10/sup -3/M had no significant effect on zinc transport to the serosal side solution or on uptake by the intestinal mucosa. This in vivo study with humans and in vitro study with rat intestine does not support a direct adverse effect of folic acid on zinc absorption.

  2. Precision Saturated Absorption Spectroscopy of H3+

    NASA Astrophysics Data System (ADS)

    Guan, Yu-chan; Liao, Yi-Chieh; Chang, Yung-Hsiang; Peng, Jin-Long; Shy, Jow-Tsong

    2016-06-01

    In our previous work on the Lamb dips of the νb{2} fundamental band of H3+, the saturated absorption spectrum was obtained by the third-derivative spectroscopy using frequency modulation [1]. However, the frequency modulation also causes error in absolute frequency determination. To solve this problem, we have built an offset-locking system to lock the OPO pump frequency to an iodine-stabilized Nd:YAG laser. With this modification, we are able to scan the OPO idler frequency precisely and obtain the profile of the Lamb dips. Double modulation (amplitude modulation of the idler power and concentration modulation of the ion) is employed to subtract the interference fringes of the signal and increase the signal-to-noise ratio effectively. To Determine the absolute frequency of the idler wave, the pump wave is offset locked on the R(56) 32-0 a10 hyperfine component of 127I2, and the signal wave is locked on a GPS disciplined fiber optical frequency comb (OFC). All references and lock systems have absolute frequency accuracy better than 10 kHz. Here, we demonstrate its performance by measuring one transition of methane and sixteen transitions of H3+. This instrument could pave the way for the high-resolution spectroscopy of a variety of molecular ions. [1] H.-C. Chen, C.-Y. Hsiao, J.-L. Peng, T. Amano, and J.-T. Shy, Phys. Rev. Lett. 109, 263002 (2012).

  3. [Digestion-flame atomic absorption spectroscopy].

    PubMed

    Xu, Liang; Hu, Jian-Guo; Liu, Rui-Ping; Wang, Zhi-Min; Narenhua

    2008-01-01

    A microwave digestion-flame atomic absorption spectroscopy (FAAS) method was developed for the determination of metal elements Na, Zn, Cu, Fe, Mn, Ca and Mg in Mongolian patents. The instrument parameters for the determination were optimized, and the appropriate digestion solvent was selected. The recovery of the method was between 95.8% and 104.3%, and the RSD was between 1.6% and 4.2%. The accuracy and precision of the method was tested by comparing the values obtained from the determination of the standard sample, bush twigs and leaves (GSV-1) by this method with the reference values of GSV-1. The determination results were found to be basically consistent with the reference values. The microwave digestion technique was applied to process the samples, and the experimental results showed that compared to the traditional wet method, the present method has the merits of simplicity, saving agents, rapidness, and non-polluting. The method was accurate and reliable, and could be used to determine the contents of seven kinds of metal elements in mongolian patents.

  4. Effect of water absorption on pollen adhesion.

    PubMed

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

    2015-03-15

    Pollens possess a thin liquid coating, pollenkitt, which plays a major role in adhesion by forming capillary menisci at interfaces. Unfortunately, the influence of humidity on pollenkitt properties and capillary adhesion is unknown. Because humidity varies widely in the environment, the answers have important implications for better understanding plant reproduction, allergy and asthma, and pollen as atmospheric condensation nuclei. Here, pollenkitt-mediated adhesion of sunflower pollen to hydrophilic and hydrophobic surfaces was measured as a function of humidity. The results quantify for the first time the significant water absorption of pollenkitt and the resulting complex dependence of adhesion on humidity. On hydrophilic Si, adhesion increased with increasing RH for pollens with or without pollenkitt, up to 200nN at 70% RH. In contrast, on hydrophobic PS, adhesion of pollenkitt-free pollen is independent of RH. Surprisingly, when pollenkitt was present adhesion forces on hydrophobic PS first increased with RH up to a maximum value at 35% RH (∼160nN), and then decreased with further increases in RH. Independent measurement of pollenkitt properties is used with models of capillary adhesion to show that humidity-dependent changes in pollenkitt wetting and viscosity are responsible for this complex adhesion behavior.

  5. Hg0 absorption in potassium persulfate solution*

    PubMed Central

    Ye, Qun-feng; Wang, Cheng-yun; Wang, Da-hui; Sun, Guan; Xu, Xin-hua

    2006-01-01

    The aqueous phase oxidation of gaseous elemental mercury (Hg0) by potassium persulfate (KPS) catalyzed by Ag+ was investigated using a glass bubble column reactor. Concentration of gaseous mercury and potassium persulfate were measured by cold vapor atom absorption (CVAA) and ion chromatograph (IC), respectively. The effects of pH value, concentration of potassium persulfate and silver nitrate (SN), temperature, Hg0 concentration in the reactor inlet and tertiary butanol (TBA), free radical scavenger, on the removal efficiency of Hg0 were studied. The results showed that the removal efficiency of Hg0 increased with increasing concentration of potassium persulfate and silver nitrate, while temperature and TBA were negatively effective. Furthermore, the removal efficiency of Hg0 was much better in neutral solution than in both acidic and alkaline solution. But the influence of pH was almost eliminated by adding AgNO3. High Hg0 concentration has positive effect. The possible reaction mechanism of gaseous mercury was also discussed. PMID:16615172

  6. Starch digestion and absorption in nonruminants.

    PubMed

    Gray, G M

    1992-01-01

    Starch digestion and absorption is augmented appreciably by physical processing of grain or legume and by heating to 100 degrees C for several minutes before its ingestion. Starch, a polysaccharide composed of alpha 1,4-linked glucose units (amylose) and alpha 1,4-1,6-linked branched structure (amylopectin), is cleaved in the duodenal cavity by secreted pancreatic alpha-amylase to a disaccharide (maltose), trisaccharide (maltotriose), and branched alpha-dextrins. These final oligosaccharides are hydrolyzed efficiently by complimentary action of three integral brush border enzymes at the intestinal surface: glucoamylase (maltase-glucoamylase, amyloglucosidase), sucrase (maltase-sucrase) and alpha-dextrinase (isomaltase). The final monosaccharide glucose product is then cotransported into the enterocyte along with Na+ by a specific brush border 75-kDa transport protein in the rate-limiting step for overall starch assimilation. By virtue of this sequential luminal and membrane digestion followed by glucose transport, starch is assimilated in a very efficient manner in nonruminants.

  7. The Zone of Inertia: Absorptive Capacity and Organizational Change

    ERIC Educational Resources Information Center

    Godkin, Lynn

    2010-01-01

    Purpose: The purpose of this paper is to describe how interruptions in organizational learning effect institutional absorptive capacity and contribute to organizational inertia. Design/methodology/approach: An exploratory model is presented as a heuristic to describe how interruptions in organizational learning affect absorptive capacity.…

  8. Meat protein fractions enhance nonheme iron absorption in humans.

    PubMed

    Hurrell, Richard F; Reddy, Manju B; Juillerat, Marcel; Cook, James D

    2006-11-01

    The nature of the enhancing effect of muscle tissue on nonheme iron absorption in humans is unclear but thought to be related to muscle proteins. We conducted radioiron absorption studies to compare iron absorption from proteins isolated from beef and chicken muscle with that from freeze-dried beef and chicken muscle and from egg albumin. All meals contained an equivalent amount of protein as part of a semisynthetic liquid formula. Freeze-dried beef and chicken muscle increased iron absorption 180% (P < 0.001) and 100% (P < 0.001), respectively, relative to egg albumin. When added to the meal at an equivalent protein level (15 g), the isolated beef protein and the isolated heme-free beef protein with 94 and 98% protein content, respectively, increased iron absorption to the same extent as the native beef muscle. Similarly, when added to the meal at an equivalent protein level (30 g), isolated chicken muscle protein (94% protein) increased iron absorption similarly to native chicken muscle. Iron absorption from the meal containing the isolated heme-free chicken protein, however, was 120% (P < 0.01) greater than from the meal containing freeze-dried chicken muscle, indicating that a nonprotein component of muscle tissue with iron-binding potential may have been removed or concentrated by the protein extraction and separation procedures. Our results support the hypothesis that the enhancing effect of muscle tissue on iron absorption is mainly protein related but indicate that other factors may also play a role.

  9. Absorption of impinging water droplet in porous stones.

    PubMed

    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.

  10. High durability solar absorptive coating and methods for making same

    DOEpatents

    Hall, Aaron C.; Adams, David P.

    2016-11-22

    The present invention relates to solar absorptive coatings including a ceramic material. In particular, the coatings of the invention are laser-treated to further enhance the solar absorptivity of the material. Methods of making and using such materials are also described.

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

    NASA Technical Reports Server (NTRS)

    Perry, E. H.

    1976-01-01

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

  12. Triple effect absorption chiller utilizing two refrigeration circuits

    DOEpatents

    DeVault, Robert C.

    1988-01-01

    A triple effect absorption method and apparatus having a high coefficient of performance. Two single effect absorption circuits are combined with heat exchange occurring between a condenser and absorber of a high temperature circuit, and a generator of a low temperature circuit. The evaporators of both the high and low temperature circuits provide cooling to an external heat load.

  13. Computer-Graphics Emulation of Chemical Instrumentation: Absorption Spectrophotometers.

    ERIC Educational Resources Information Center

    Gilbert, D. D.; And Others

    1982-01-01

    Describes interactive, computer-graphics program emulating behavior of high resolution, ultraviolet-visible analog recording spectrophotometer. Graphics terminal behaves as recording absorption spectrophotometer. Objective of the emulation is study of optimization of the instrument to yield accurate absorption spectra, including…

  14. IN VITRO DERMAL ABSORPTION OF FLAME RETARDANT CHEMICALS

    EPA Science Inventory

    ABSTRACT
    The use of flame retardant chemicals in furniture fabric could pose a potential health risk to consumers from dermal absorption of these compounds. The objective of this study was to examine the in vitro dermal absorption of two flame retardant chemicals, [14C]-d...

  15. Water absorption properties of ultrasonic treated brown rice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To understand the effect of ultrasonic treated on brown rice, it is important to research the water absorption processing of brown rice before and after ultrasonic treatment. The objective of this study was investigate and modeling water absorption characteristics of brown rice using Peleg’s equatio...

  16. Heterogeneous porous structures for the fastest liquid absorption

    NASA Astrophysics Data System (ADS)

    Shou, Dahua; Ye, Lin; Fan, Jintu

    2013-08-01

    Engineered porous materials, which have fast absorption of liquids under global constraints (e.g. volume, surface area, or cost of the materials), are useful in many applications including moisture management fabrics, medical wound dressings, paper-based analytical devices, liquid molding composites, etc.. The absorption in capillary tubes and porous media is driven by the surface tension of liquid, which is inversely proportional to the pore size. On the contrary, the ability of conduction (or permeability) of liquid in porous materials is linear with the square of pore size. Both mechanisms superimpose with each other leading to a possibility of the fastest absorption for a porous structure. In this work, we explore the flow behaviors for the fastest absorption using heterogeneous porous architectures, from two-portion tubes to two-layer porous media. The absorption time for filling up the voids in these porous materials is expressed in terms of pore size, height and porosity. It is shown that under the given height and void volume, these two-component porous structures with a negative gradient of pore size/porosity against the imbibition direction, have a faster absorption rate than controlled samples with uniform pore size/porosity. Particularly, optimal structural parameters including pore size, height and porosity are found for the minimum absorption time. The obtained results will be used as a priori for the design of porous structures with excellent water absorption and moisture management property in various fields.

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

    PubMed Central

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

    1997-01-01

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

  18. Carbon Dioxide Absorption in a Membrane Contactor with Color Change

    ERIC Educational Resources Information Center

    Pantaleao, Ines; Portugal, Ana F.; Mendes, Adelio; Gabriel, Joaquim

    2010-01-01

    A pedagogical experiment is described to examine the physical absorption of gases, in this case carbon dioxide, in a hollow fiber membrane contactor (HFMC) where the absorption concentration profile can be followed by a color change. The HFMC is used to teach important concepts and can be used in interesting applications for students, such as…

  19. Two-color excited-state absorption imaging of melanins

    NASA Astrophysics Data System (ADS)

    Fu, Dan; Ye, Tong; Matthews, Thomas E.; Yurtsever, Gunay; Hong, Lian; Simon, John D.; Warren, Warren S.

    2007-02-01

    We have demonstrated a new method for imaging melanin with two-color excited state absorption microscopy. If one of two synchronized mode-locked pulse trains at different colors is intensity modulated, the modulation transfers to the other pulse train when nonlinear absorption takes place in the medium. We can easily measure 10 -6 absorption changes caused by either instantaneous two-photon absorption or relatively long lived excited state absorption with a RF lock-in amplifier. Eumelanin and pheomelanin exhibit similar excited state dynamics. However, their difference in excited state absorption and ground state absorption leads to change in the phase of the transient absorption signal. Scanning microscopic imaging is performed with B16 cells, melanoma tissue to demonstrate the 3D high resolution imaging capability. Different melanosome samples are also imaged to illustrate the differences between eumelanin and pheomelanin signals. These differences could enable us to image their respective distribution in tissue samples and provide us with valuable information in diagnosing malignant transformation of melanocytes.

  20. Paramagnetic Materials for PASER and Tunable RF Absorption

    SciTech Connect

    Antipov, Sergey P.; Schoessow, Paul; Kanareykin, Alexei; Jing Chunguang; Poluektov, Oleg; Gai Wei

    2010-11-04

    We report on the use of paramagnetic active media for the PASER (Particle Acceleration by Stimulated Emission of Radiation) and for dielectric loaded accelerating structures with tunable absorption for high order modes. The dielectric is doped with a material exhibiting high paramagnetic resonance, e.g. ruby with Cr{sup 3+}. The absorption frequency can be tuned by a magnetic field.

  1. Microdroplet Sample Application in Electrothermal Atomization for Atomic Absorption Spectrometry.

    DTIC Science & Technology

    1982-03-29

    ad ideftify by Week amber) atomic absorption spectroscopy microsampl ing graphite- furnace AAS automation C> 20. AOSTRACT (Coninuhe an reveresi de It...furnace and spectrometer system as well as for partial support of this project. REFERENCES 1. J. D. Winefordner, Atomic Absorption Spectroscopy , G. F

  2. Optoacoustic spectroscopy and its application to molecular and particle absorption

    NASA Astrophysics Data System (ADS)

    Trees, Charles C.; Voss, Kenneth J.

    1990-09-01

    Light absorption in the ocean has been the least studied optical property because of the difficulties in making accurate measurements. With the previously used techniques, large differences have been reported for the specific absorption coefficient of phytoplankton (cultures and natural assemblages). It is difficult to determine if the diversity in these values are methodological or a function of actual variations in absorption. With the renewed interest and activity in optoacoustic spectroscopy (OAS), which accurately measures absorption, some of these discrepancies should be resolved. In this method, as molecules and particles absorb light from a modulated source, they thermally expand and contract, thereby generating acoustic waves, at the modulation frequency, which are detected by a hydrophone. Optoacoustic spectroscopy is ideally suited for measuring dissolved organic material and particle absorptions because of its high sensitivity (105m1) and the egligible effect of scattered light. In this paper the instrumental design for an optoacoustic spectrophotometer (OAS), which pecifically measures phytoplankton absorption (420-S5Onm), is described. The spectral absorption of dissolved organic material and a phytoplankton culture is presented. OAS holds promise in being able to measure absorption without use of either filtration or concentration techniques.

  3. An in silico skin absorption model for fragrance materials.

    PubMed

    Shen, Jie; Kromidas, Lambros; Schultz, Terry; Bhatia, Sneha

    2014-12-01

    Fragrance materials are widely used in cosmetics and other consumer products. The Research Institute for Fragrance Materials (RIFM) evaluates the safety of these ingredients and skin absorption is an important parameter in refining systemic exposure. Currently, RIFM's safety assessment process assumes 100% skin absorption when experimental data are lacking. This 100% absorption default is not supportable and alternate default values were proposed. This study aims to develop and validate a practical skin absorption model (SAM) specific for fragrance material. It estimates skin absorption based on the methodology proposed by Kroes et al. SAM uses three default absorption values based on the maximum flux (J(max)) - namely, 10%, 40%, and 80%. J(max) may be calculated by using QSAR models that determine octanol/water partition coefficient (K(ow)), water solubility (S) and permeability coefficient (K(p)). Each of these QSAR models was refined and a semi-quantitative mechanistic model workflow is presented. SAM was validated with a large fragrance-focused data set containing 131 materials. All resulted in predicted values fitting the three-tiered absorption scenario based on Jmax ranges. This conservative SAM may be applied when fragrance material lack skin absorption data.

  4. 2. VIEW IN ROOM 111, ATOMIC ABSORPTION BERYLLIUM ANALYSIS LABORATORY. ...

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

    2. VIEW IN ROOM 111, ATOMIC ABSORPTION BERYLLIUM ANALYSIS LABORATORY. AIR FILTERS AND SWIPES ARE DISSOLVED WITH ACIDS AND THE REMAINING RESIDUES ARE SUSPENDED IN NITRIC ACID SOLUTION. THE SOLUTION IS PROCESSED THROUGH THE ATOMIC ABSORPTION SPECTROPHOTOMETER TO DETECT THE PRESENCE AND LEVELS OF BERYLLIUM. - Rocky Flats Plant, Health Physics Laboratory, On Central Avenue between Third & Fourth Streets, Golden, Jefferson County, CO

  5. Polyamidoamine dendrimers as novel potential absorption enhancers for improving the small intestinal absorption of poorly absorbable drugs in rats.

    PubMed

    Lin, Yulian; Fujimori, Takeo; Kawaguchi, Naoko; Tsujimoto, Yuiko; Nishimi, Mariko; Dong, Zhengqi; Katsumi, Hidemasa; Sakane, Toshiyasu; Yamamoto, Akira

    2011-01-05

    Effects of polyamidoamine (PAMAM) dendrimers on the intestinal absorption of poorly absorbable drugs were examined by an in situ closed loop method in rats. 5(6)-Carboxyfluorescein (CF), fluorescein isothiocyanate-dextrans (FDs) with various molecular weights, calcitonin and insulin were used as model drugs of poorly absorbable drugs. The absorption of CF, FD4 and calcitonin from the rat small intestine was significantly enhanced in the presence of PAMAM dendrimers. The absorption-enhancing effects of PAMAM dendrimers for improving the small intestinal absorption of CF were concentration and generation dependent and a maximal absorption-enhancing effect was observed in the presence of 0.5% (w/v) G2 PAMAM dendrimer. However, G2 PAMAM dendrimer had almost no absorption-enhancing effect on the small intestinal absorption of macromolecular drugs including FD10 and insulin. Overall, the absorption-enhancing effects of G2 PAMAM dendrimer in the small intestine decreased as the molecular weights of drug increased. However, G2 PAMAM dendrimer did not enhance the intestinal absorption of these drugs with different molecular weights in the large intestine. Furthermore, we evaluated the intestinal membrane damage with or without G2 PAMAM dendrimer. G2 PAMAM dendrimer (0.5% (w/v)) significantly increased the activities of lactate dehydrogenase (LDH) and the amounts of protein released from the intestinal membranes, but the activities and amounts of these toxic markers were less than those in the presence of 3% Triton X-100 used as a positive control. Moreover, G2 PAMAM dendrimer at concentrations of 0.05% (w/v) and 0.1% (w/v) did not increase the activities and amounts of these toxic markers. These findings suggested that PAMAM dendrimers at lower concentrations might be potential and safe absorption enhancers for improving absorption of poorly absorbable drugs from the small intestine.

  6. Free-Carrier Absorption in Silicon from First Principles

    NASA Astrophysics Data System (ADS)

    Shi, Guangsha; Kioupakis, Emmanouil

    The absorption of light by free carriers in semiconductors such as silicon results in intraband electron or hole excitations, and competes with optical transitions across the band gap. Free-carrier absorption therefore reduces the efficiency of optoelectronic devices such as solar cells because it competes with the generation of electron-hole pairs. In this work, we use first-principles calculations based on density functional theory to investigate direct and phonon-assisted free-carrier absorption in silicon. We determine the free-carrier absorption coefficient as a function of carrier concentration and temperature and compare to experiment. We also identify the dominant phonon modes that contributing to phonon-assisted free-carrier absorption processes, and analyze the results to evaluate the impact of this loss mechanism on the efficiency of silicon solar cells. This research was supported by the National Science Foundation CAREER award through Grant No. DMR-1254314. Computational resources were provided by the DOE NERSC facility.

  7. Temperature effects on dynamic water absorption into paper.

    PubMed

    Songok, Joel; Salminen, Pekka; Toivakka, Martti

    2014-03-15

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

  8. A plant canopy light absorption model with application to wheat

    NASA Technical Reports Server (NTRS)

    Chance, J. E.; Lemaster, E. W.

    1977-01-01

    From the light absorption model the absorption of light in the photosynthetically active region of the spectrum was calculated for a Penjamo wheat crop for several situations including: (1) the percent absorption of the incident radiation by a canopy having a four layer structure; (2) the percent absorption of light by the individual layers within a four layer canopy and by the underlying soil; (3) the percent absorption of light by each vegetative canopy layer for variable sun angle; and (4) the cumulative solar energy absorbed by the developing wheat canopy as it progresses from a single layer through its growth stages to a three layer canopy. This calculation was also presented as a function of the leaf area index.

  9. Optomechanically induced transparency and absorption in hybridized optomechanical systems

    NASA Astrophysics Data System (ADS)

    Hou, B. P.; Wei, L. F.; Wang, S. J.

    2015-09-01

    We present the normal-mode splitting and optomechanically induced transparency or absorption phenomena in the strongly tunnel-coupled optomechanical cavities. In the probe output spectrum, there appear central transparency windows or absorption peaks around which two broad sidebands are symmetrically located. It has been confirmed by the quantitative findings that two broad sidebands, which include the distorted absorption peaks, indicate the normal-mode splitting of the two hybridized cavities, and central transparency windows or absorption peaks character the interference induced by the optomechanical interactions. Additionally, the switching from absorption to amplification can be realized by only adjusting the tunnel interaction. These spectrum properties can be used for the coherent control of light pulses via microfabricated optomechanical arrays.

  10. Production of silicon modified to have enhanced infrared absorption

    NASA Astrophysics Data System (ADS)

    Weld, E.; Ayachitula, R.; de La Harpe, K.; Brandt, L.; Chilton, M.; Knize, R. J.; Patterson, B. M.

    2014-03-01

    We demonstrate the enhanced optical properties of silicon microstructures formed by irradiation of a silicon wafer by a modulated continuous wave (CW) laser beam in the presence of SF6. The microstructures are doped with about 0.6% sulfur, which extends the absorption well below the 1.1um bandgap of crystalline silicon and results in a 60% increase in the absorption of infrared radiation. The microstructured silicon produced using microsecond pulses of CW light demonstrates comparable infrared absorption enhancement to black silicon made using more expensive and complicated laser systems. This enhanced absorption as a result of these microstructures has been studied over the past decade in an effort to create high responsivity detectors and night vision goggles and improve the efficiency of solar cells. We will also discuss additional methods that allow tunability and scalability in the production of silicon modified to demonstrate increased infrared absorption.

  11. Design of plasmonic circular grating with broadband absorption enhancements

    NASA Astrophysics Data System (ADS)

    Chiu, Nan-Fu; Yang, Cheng-Du; Kao, Yi-Lun; Cheng, Chih-Jen

    2015-05-01

    We have investigated the effect of concentric circles geometry on the performance of focusing plasmonic circular grating (PCG)-coupled surface-omnidirectional absorption. We wish to highlight the essential characteristics of plasmonic circular grating nanostructure to assist researchers in developing and advancing suitable organic solar cells (OSC) for unique applications. Exactly how plasmonic enhancement and the absorption characteristics of the organic materials (P3HT:PCBM and PEDOT:PSS) interact with each other is also examined. We present experimental studies of broadband absorption enhancement in PCG structure. We show that the PCG structure can result in broadband absorption enhancement, the overall optical absorption in organic film can be greatly enhanced up to ~111.2 % compared to the planar device without grating.

  12. Effect of partial absorption on diffusion with resetting.

    PubMed

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

    2013-02-01

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

  13. Quantum of optical absorption in two-dimensional semiconductors.

    PubMed

    Fang, Hui; Bechtel, Hans A; Plis, Elena; Martin, Michael C; Krishna, Sanjay; Yablonovitch, Eli; Javey, Ali

    2013-07-16

    The optical absorption properties of free-standing InAs nanomembranes of thicknesses ranging from 3 nm to 19 nm are investigated by Fourier transform infrared spectroscopy. Stepwise absorption at room temperature is observed, arising from the interband transitions between the subbands of 2D InAs nanomembranes. Interestingly, the absorptance associated with each step is measured to be ∼1.6%, independent of thickness of the membranes. The experimental results are consistent with the theoretically predicted absorptance quantum, AQ = πα/nc for each set of interband transitions in a 2D semiconductor, where α is the fine structure constant and nc is an optical local field correction factor. Absorptance quantization appears to be universal in 2D systems including III-V quantum wells and graphene.

  14. Mechanochemical Tuning of Pyrene Absorption Spectrum Using Force Probes.

    PubMed

    Fernández-González, Miguel Ángel; Rivero, Daniel; García-Iriepa, Cristina; Sampedro, Diego; Frutos, Luis Manuel

    2017-02-14

    Control of absorption spectra in chromophores is a fundamental aspect of many photochemical and photophysical processes as it constitutes the first step of the global photoinduced process. Here we explore the use of mechanical forces to modulate the light absorption process. Specifically, we develop a computational formalism for determining the type of mechanical forces permitting a global tuning of the absorption spectrum. This control extends to the excitation wavelength, absorption bands overlap, and oscillator strength. The determination of these optimal forces permits us to rationally guide the design of new mechano-responsive chromophores. Pyrene has been chosen as the case study for applying these computational tools because significant absorption spectra information is available for the chromophore as well as for different strained derivatives. Additionally, pyrene presents a large flexibility, which makes it a good system to test the inclusion of force probes as the strategy to exert forces on the system.

  15. Energy Absorption in a Shear-Thickening Fluid

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  16. Absorption of surface acoustic waves by topological insulator thin films

    SciTech Connect

    Li, L. L.; Xu, W.

    2014-08-11

    We present a theoretical study on the absorption of the surface acoustic waves (SAWs) by Dirac electrons in topological insulator (TI) thin films (TITFs). We find that due to momentum and energy conservation laws, the absorption of the SAWs in TITFs can only be achieved via intra-band electronic transitions. The strong absorption can be observed up to sub-terahertz frequencies. With increasing temperature, the absorption intensity increases significantly and the cut-off frequency is blue-shifted. More interestingly, we find that the absorption of the SAWs by the TITFs can be markedly enhanced by the tunable subgap in the Dirac energy spectrum of the TI surface states. Such a subgap is absent in conventional two-dimensional electron gases (2DEGs) and in the gapless Dirac 2DEG such as graphene. This study is pertinent to the exploration of the acoustic properties of TIs and to potential application of TIs as tunable SAW devices working at hypersonic frequencies.

  17. Absorption of surface acoustic waves by topological insulator thin films

    NASA Astrophysics Data System (ADS)

    Li, L. L.; Xu, W.

    2014-08-01

    We present a theoretical study on the absorption of the surface acoustic waves (SAWs) by Dirac electrons in topological insulator (TI) thin films (TITFs). We find that due to momentum and energy conservation laws, the absorption of the SAWs in TITFs can only be achieved via intra-band electronic transitions. The strong absorption can be observed up to sub-terahertz frequencies. With increasing temperature, the absorption intensity increases significantly and the cut-off frequency is blue-shifted. More interestingly, we find that the absorption of the SAWs by the TITFs can be markedly enhanced by the tunable subgap in the Dirac energy spectrum of the TI surface states. Such a subgap is absent in conventional two-dimensional electron gases (2DEGs) and in the gapless Dirac 2DEG such as graphene. This study is pertinent to the exploration of the acoustic properties of TIs and to potential application of TIs as tunable SAW devices working at hypersonic frequencies.

  18. Effect of partial absorption on diffusion with resetting

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

  19. Excitonic absorption intensity of semiconducting and metallic carbon nanotubes.

    PubMed

    Verdenhalven, Eike; Malić, Ermin

    2013-06-19

    The knowledge of the intrinsic absorption intensity of each carbon nanotube is of crucial importance for the optical assignment of nanotube species and the estimation of their abundance in a sample. Based on a microscopic approach, we calculate excitonic absorption spectra for a variety of semiconducting and metallic nanotubes, revealing a clear diameter, chirality, and family dependence of the absorption intensity. In particular, we also study the appearance of excited excitonic transitions, which are shown to be well pronounced for semiconducting nanotubes, reaching intensities of up to 10% of the main transition. We find that nanotubes with large diameters show the most pronounced absorption intensities, confirming well the experimentally observed trend. Depending on the CNT family and transition, the absorption is enhanced or reduced with the chiral angle. This behavior reflects well the qualitative chirality dependence of the analytically derived optical matrix element.

  20. Exercise, Insulin Absorption Rates, and Artificial Pancreas Control

    NASA Astrophysics Data System (ADS)

    Frank, Spencer; Hinshaw, Ling; Basu, Rita; Basu, Ananda; Szeri, Andrew J.

    2016-11-01

    Type 1 Diabetes is characterized by an inability of a person to endogenously produce the hormone insulin. Because of this, insulin must be injected - usually subcutaneously. The size of the injected dose and the rate at which the dose reaches the circulatory system have a profound effect on the ability to control glucose excursions, and therefore control of diabetes. However, insulin absorption rates via subcutaneous injection are variable and depend on a number of factors including tissue perfusion, physical activity (vasodilation, increased capillary throughput), and other tissue geometric and physical properties. Exercise may also have a sizeable effect on the rate of insulin absorption, which can potentially lead to dangerous glucose levels. Insulin-dosing algorithms, as implemented in an artificial pancreas controller, should account accurately for absorption rate variability and exercise effects on insulin absorption. The aforementioned factors affecting insulin absorption will be discussed within the context of both fluid mechanics and data driven modeling approaches.