Enhancement of the atomic absorbance of Cr, Zn, Cd, and Pb in metal furnace atomic absorption spectrometry using absorption tubes

Directory of Open Access Journals (Sweden)

Yuya Koike

2017-03-01

Full Text Available Trace amounts of Cr, Zn, Cd, and Pb were determined by metal furnace atomic absorption spectrometry using absorption tubes. Various absorption tubes were designed as roof- and tube-types, and fixed above the metal furnace in order to extend the light path length. Aqueous standards and samples were injected in the metal furnace and atomized in a metal atomizer with an absorption tube (6 cm length, 15.5 mm diameter. The used of an absorption tube resulted in an enhancement of the atomic absorbance. The ratios of absorbance values with and without the roof- and tube-type absorption tubes were 1.33 and 1.11 for Cr; 1.42 and 1.99 for Zn; 1.66 and 1.98 for Cd; and 1.31 and 1.16 for Pb, respectively. The use of an absorption tube was effective for Zn and Cd analysis, as the absorbance values for these low boiling point metals doubled. The proposed method was successfully applied in the determination of Zn in tap water.

Wavelength modulation diode laser absorption spectroscopy for high-pressure gas sensing

Science.gov (United States)

Sun, K.; Chao, X.; Sur, R.; Jeffries, J. B.; Hanson, R. K.

2013-03-01

A general model for 1 f-normalized wavelength modulation absorption spectroscopy with nf detection (i.e., WMS- nf) is presented that considers the performance of injection-current-tuned diode lasers and the reflective interference produced by other optical components on the line-of-sight (LOS) transmission intensity. This model explores the optimization of sensitive detection of optical absorption by species with structured spectra at elevated pressures. Predictions have been validated by comparison with measurements of the 1 f-normalized WMS- nf (for n = 2-6) lineshape of the R(11) transition in the 1st overtone band of CO near 2.3 μm at four different pressures ranging from 5 to 20 atm, all at room temperature. The CO mole fractions measured by 1 f-normalized WMS-2 f, 3 f, and 4 f techniques agree with calibrated mixtures within 2.0 %. At conditions where absorption features are significantly broadened and large modulation depths are required, uncertainties in the WMS background signals due to reflective interference in the optical path can produce significant error in gas mole fraction measurements by 1 f-normalized WMS-2 f. However, such potential errors can be greatly reduced by using the higher harmonics, i.e., 1 f-normalized WMS- nf with n > 2. In addition, less interference from pressure-broadened neighboring transitions has been observed for WMS with higher harmonics than for WMS-2 f.

Intestinal absorption of copper: influence of carbohydrates.

Science.gov (United States)

Wapnir, R A; Balkman, C

1992-02-01

Macronutrients can modulate the intestinal absorption of trace elements by binding the metal or altering mucosal function. We investigated whether certain simple and complex carbohydrates modify copper (Cu) absorption, using an in vivo perfusion technique in the rat. Corn syrup solids, which contain a mixture of glucose polymers of diverse length, added at either 20 or 50 mosm/kg enhanced Cu absorption from a 31.5 microM (2 mg/liter) Cu solution (128 +/- 11 and 130 +/- 11 pmol/min x cm, respectively, vs 101 +/- 4 pmol/min x cm, P less than 0.05, in the absence of carbohydrate). This was concomitant with a stimulation of net water absorption (1.05 +/- 0.08 and 0.84 +/- 0.08 microliter/min x cm, respectively, vs 0.63 +/- 0.02 microliter/min x cm with no carbohydrate, P less than 0.05). Glucose, fructose, lactose, or sucrose had no influence on Cu absorption, although they altered water exchanges, an effect attributable to a reduction of the outflow component of fluid recirculation. Low concentrations of lactose resulted in a greater accumulation of Cu in the intestinal mucosa (8.75 +/- 0.71 micrograms/g vs 5.77 +/- 0.68 micrograms/g for controls, P less than 0.05). Hence, solutes that moderately stimulate mucosa-to-serosa fluid influx in a progressive manner, such as glucose polymers, may contribute to functionally increase Cu absorption. Conversely, conditions which tend to reduce water inflow or increase water outflow across the small intestinal mucosa, as may occur with high lactose diets or in cases of chronic diarrhea, may have negative effects.

Ultrafast THz Saturable Absorption in Semiconductors

DEFF Research Database (Denmark)

Turchinovich, Dmitry; Hoffmann, Matthias C.

2011-01-01

We demonstrate THz saturable absorption in n-doped semiconductors GaAs, GaP, and Ge in a nonlinear THz time-domain spectroscopy experiment. Saturable absorption is caused by sample conductivity modulation due to electron heating and satellite valley scattering in the field of a strong THz pulse....

Reversible unidirectional reflection and absorption of PT-symmetry structure under electro-optical modulation

Science.gov (United States)

Fang, Yun-tuan; Zhang, Yi-chi; Xia, Jing

2018-06-01

In order to obtain tunable unidirectional device, we assumed an ideal periodic layered Parity-Time (PT) symmetry structure inserted by doped LiNbO3 (LN) interlayers. LN is a typical electro-optical material of which the refractive index depends on the external electric field. In our work, we theoretically investigate the modulation effect of the external electric field on the transmittance and reflectance of the structure through numerical method. Through selected structural parameters, the one-way enhanced reflection and high absorption (above 0.9) behaviors are found. Within a special frequency band (not a single frequency), our theoretical model performs enhanced reflection in one incidence direction and high absorption in the other direction. Furthermore, the directions of enhanced reflection and absorption can be reversed through reversing the direction of applied electric field. Such structure with reversible properties has the potential in designing new optical devices.

Enhancement of the static extinction ratio by using a dual-section distributed feedback laser integrated with an electro-absorption modulator

Science.gov (United States)

Cho, Chun-Hyung; Kim, Jongseong; Sung, Hyuk-Kee

2016-09-01

We report on the enhancement of the static extinction ratio by using a dual-section distributed feedback laser diode integrated with an electro-absorption modulator. A directly- modulated dual-section laser can provide improved modulation performance under a low bias level ( i.e., below the threshold level) compared with a standard directly-modulated laser. By combining the extinction ratio from a dual-section laser with that from an electro-absorption modulator section, a total extinction ratio of 49.6. dB are successfully achieved.

Absorptivity modulation on wavy molten steel surfaces: The influence of laser wavelength and angle of incidence

International Nuclear Information System (INIS)

Kaplan, A. F. H.

2012-01-01

The modulation of the angle-dependent Fresnel absorptivity across wavy molten steel surfaces during laser materials processing, like drilling, cutting, or welding, has been calculated. The absorptivity is strongly altered by the grazing angle of incidence of the laser beam on the processing front. Owing to its specific Brewster-peak characteristics, the 10.64 μm wavelength CO 2 -laser shows an opposite trend with respect to roughness and angle-of-incidence compared to lasers in the wavelength range of 532-1070 nm. Plateaus or rings of Brewster-peak absorptivity can lead to hot spots on a wavy surface, often in close proximity to cold spots caused by shadow domains.

Ultrafast THz Saturable Absorption in Doped Semiconductors

DEFF Research Database (Denmark)

Turchinovich, Dmitry; Hoffmann, Matthias C.

2011-01-01

We demonstrate ultrafast THz saturable absorption in n-doped semiconductors by nonlinear THz time-domain spectroscopy. This effect is caused by the semiconductor conductivity modulation due to electron heating and satellite-valley scattering in strong THz fields.......We demonstrate ultrafast THz saturable absorption in n-doped semiconductors by nonlinear THz time-domain spectroscopy. This effect is caused by the semiconductor conductivity modulation due to electron heating and satellite-valley scattering in strong THz fields....

Integration of electro-absorption modulator in a vertical-cavity surface-emitting laser

Science.gov (United States)

Marigo-Lombart, L.; Calvez, S.; Arnoult, A.; Rumeau, A.; Viallon, C.; Thienpont, H.; Panajotov, K.; Almuneau, G.

2018-02-01

VCSELs became dominant laser sources in many short optical link applications such as datacenter, active cables, etc. Actual standards and commercialized VCSEL are providing 25 Gb/s data rates, but new solutions are expected to settle the next device generation enabling 100 Gb/s. Directly modulated VCSEL have been extensively studied and improved to reach bandwidths in the range of 26-32 GHz [Chalmers, TU Berlin], however at the price of increased applied current and thus reduced device lifetime. Furthermore, the relaxation oscillation limit still subsists with this solution. Thus, splitting the emission and the modulation functions as done with DFB lasers is a very promising alternative [TI-Tech, TU Berlin]. Here, we study the vertical integration of an ElectroAbsorption Modulator (EAM) within a VCSEL, where the output light of the VCSEL is modulated through the EAM section. In our original design, we finely optimized the EAM design to maximize the modulation depth by implementing perturbative Quantum Confined Stark Effect (QCSE) calculations, while designing the vertical integration of the EAM without penalty on the VCSEL static performances. We will present the different fabricated vertical structures, as well as the experimental electrical and optical static measurements for those configurations demonstrating a very good agreement with the reflectivity and absorption simulations obtained for both the VCSEL and the EAM-VCSEL structures. Finally, to reach very high frequency modulation we studied the BCB electrical properties up to 110 GHz and investigated coplanar and microstrip lines access to decrease both the parasitic capacitance and the influence of the substrate.

[Study on lead absorption in pumpkin by atomic absorption spectrophotometry].

Science.gov (United States)

Li, Zhen-Xia; Sun, Yong-Dong; Chen, Bi-Hua; Li, Xin-Zheng

2008-07-01

A study was carried out on the characteristic of lead absorption in pumpkin via atomic absorption spectrophotometer. The results showed that lead absorption amount in pumpkin increased with time, but the absorption rate decreased with time; And the lead absorption amount reached the peak in pH 7. Lead and cadmium have similar characteristic of absorption in pumpkin.

Absorption heat cycles. An experimental and theoretical study

International Nuclear Information System (INIS)

Abrahamsson, K.

1993-09-01

A flow sheeting programme, SHPUMP, was developed for simulating different absorption heat cycles. The programme consists of ten different modules which allow the user to construct his own absorption cycle. The ten modules configurate evaporators, absorbers, generators, rectifiers, condensers, solution heat exchangers, pumps, valves, mixers and splitters. Seven basic and well established absorption cycles are available in the configuration data base of the programme. A new Carnot model is proposed heat cycles. Together with exergy analysis, general equations for the Carnot coefficient of performance and equations for thermodynamic efficiency, exergetic efficiency and exergy index, are derived, discussed and compared for both absorption heat pumps and absorption heat transformers. Utilizing SHPUMP, simulation results are presented for different configurations where absorption heat cycles are suggested to be incorporated in three different unit operations within both pulp and paper and oleochemical industries. One of the application studies reveled that an absorption heat transformer incorporated with an evaporation plant in a major pulp and paper industry, would save 18% of the total prime energy consumption in one of the evaporation plants. It was also concluded that installing an absorption heat pump in a paper drying plant would result in steam savings equivalent to 12 MW. An experimental absorption heat transformer unit operating with self-circulation has been modified and thoroughly tested. A reference heat transformer plant has been designed and installed in a major pulp and paper mill where it is directly incorporated with one of the evaporation plants. Preliminary plant operation data are presented. 72 refs, 63 figs, 33 tabs

Modulated ECH power absorption measurements using a diamagnetic loop in the TCV tokamak

International Nuclear Information System (INIS)

Manini, A.; Moret, J.M.; Alberti, S.; Goodman, T.P.; Henderson, M.A.

2001-10-01

The additional power absorbed by the plasma can be determined from the time derivative of the total plasma energy, which can be estimated from the diamagnetic flux of the plasma using a Diamagnetic Loop (DML). The main difficulty in using diamagnetic measurements to estimate the kinetic energy is the compensation of the flux measurement sensitivity to poloidal magnetic fields, which is not always easy to adjust. A method based on the temporal variations of the diamagnetic flux of the plasma during Modulated Electron Cyclotron Heating (MECH) has been developed. Using MECH has the advantage that these poloidal fields are not significantly modulated and a good compensation of these fields is not necessary. However, a good compensation of the vessel poloidal image current is crucial to ensure a sufficiently large bandwidth. The application of this diagnostic to studies of the extraordinary mode (X-mode) absorption at the third electron cyclotron harmonic frequency (X3) has been performed on the TCV Tokamak in plasmas pre-heated by X-mode at the second harmonic (X2). A MECH frequency scan has allowed the determination of an optimum modulation frequency, situated at about 200- 250 Hz. Based on this diagnostic, full single-pass absorption of the injected X3 power was measured with the X2 pre-heating in co-current drive. This high absorption is more than a factor of 2 higher than the one predicted by the linear ray tracing code TORAY. Experimental evidence indicates that a large fraction of the X3 power is absorbed by electrons in an energetic tail created by the X2 pre-heating. (author)

Direction dependence of the magneto-optical absorption in nanowires with Rashba interaction

Energy Technology Data Exchange (ETDEWEB)

Sakr, M.R., E-mail: msakr@alexu.edu.eg

2016-09-16

We study the directional dependence of the absorption spectrum of ballistic nanowires in the presence of gate-controlled Rashba spin–orbit interaction and an in-plane magnetic field. In the weak Rashba regime, our analytical and numerical results show that the absorption peaks associated with the first and third intersubband transitions exhibit frequency shifts and strong amplitude modulations as the direction of the magnetic field changes. If the field is parallel to the nanowire axis, these peaks disappear and the resonance frequencies of the whole absorption spectrum are given merely in terms of the Zeeman splitting and the energy scale characterizing the confinement potential. The second transition has an absorption peak that suffers an opposite frequency shift with amplitude that is largely direction independent. The amplitude modulation and frequency shift of the absorption spectrum is periodic in the angle that the magnetic field makes with the nanowire axis. - Highlights: • Absorption spectrum of the nanowire is calculated in the weak Rashba regime. • First and third absorption peaks show amplitude and frequency modulation. • They disappear if the magnetic field is along the wire axis, forbidden transitions. • The second transition peak shows frequency shift with minor amplitude modulation. • The frequency and amplitude modulations are periodic in the direction of the field.

Enhancing light absorption within the carrier transport length in quantum junction solar cells.

Science.gov (United States)

Fu, Yulan; Hara, Yukihiro; Miller, Christopher W; Lopez, Rene

2015-09-10

Colloidal quantum dot (CQD) solar cells have attracted tremendous attention because of their tunable absorption spectrum window and potentially low processing cost. Recently reported quantum junction solar cells represent a promising approach to building a rectifying photovoltaic device that employs CQD layers on each side of the p-n junction. However, the ultimate efficiency of CQD solar cells is still highly limited by their high trap state density in both p- and n-type CQDs. By modeling photonic structures to enhance the light absorption within the carrier transport length and by ensuring that the carrier generation and collection efficiencies were both augmented, our work shows that overall device current density could be improved. We utilized a two-dimensional numerical model to calculate the characteristics of patterned CQD solar cells based on a simple grating structure. Our calculation predicts a short circuit current density as high as 31  mA/cm2, a value nearly 1.5 times larger than that of the conventional flat design, showing the great potential value of patterned quantum junction solar cells.

Comparison of electrothermal atomization diode laser Zeeman- and wavelength-modulated atomic absorption and coherent forward scattering spectrometry

International Nuclear Information System (INIS)

Blecker, Carlo R.; Hermann, Gerd M.

2009-01-01

Atomic absorption and coherent forward scattering spectrometry by using a near-infrared diode laser with and without Zeeman and wavelength modulation were carried out with graphite furnace electrothermal atomization. Analytical curves and limits of detection were compared. The magnetic field was modulated with 50 Hz, and the wavelength of the diode laser with 10 kHz. Coherent forward scattering was measured with crossed and slightly uncrossed polarizers. The results show that the detection limits of atomic absorption spectrometry are roughly the same as those of coherent forward scattering spectrometry with crossed polarizers. According to the theory with bright flicker noise limited laser sources the detection limits and linear ranges obtained with coherent forward scattering spectrometry with slightly uncrossed polarizers are significantly better than those obtained with crossed polarizers and with atomic absorption spectrometry. This is due to the fact that employing approaches of polarization spectroscopy reduce laser intensity fluctuations to their signal carried fractions

Exploitation of a diamagnetic loop for modulated ECH power absorption measurements in TCV

International Nuclear Information System (INIS)

Manini, A.; Moret, J.M.; Alberti, S.; Goodman, T.P.; Henderson, M.A.

2003-01-01

For the evaluation of the performance of auxiliary heating methods and for the understanding of the transport properties of auxiliary heated plasmas, it is of fundamental importance to determine the fraction of the launched power that is actually transferred to the plasma, as well as where in the plasma the power is deposited. The diagnostic which is probably the best suited for the first goal is the Diamagnetic Loop (DML) providing a measurement of the diamagnetic flux of the plasma, which is directly related to the total plasma kinetic energy. TCV is equipped with a very versatile Electron Cyclotron Heating (ECH) system. It consists of six gyrotrons operating at the second harmonic, 82.7 GHz, and three gyrotrons at the third harmonic, 118 GHz. The nominal power for each 82.7 GHz gyrotron is 465 kW and for each 118 GHz gyrotron is 480 kW, resulting in a total of radio frequency power of 4.2 MW. In this paper we present the method that has been developed for determining the absorbed power in the ECH experiments in TCV, pointing out especially the results of the first third harmonic X-Mode (X3) ECH experiments, leaving the problem of the power deposition localisation to other reports. For the determination of the total plasma kinetic energy, the DML has also been used on other devices such as JET, ASDEX and TEXTOR, but only for this last case modulation experiments have been performed and analysed. Modulated ECH has been used to determine the ECH X2 and X3 power absorption from the measurement of the diamagnetic flux variations using the DML. Since only the modulation contribution is relevant to the analysis, the method does not require a perfect compensation of the diamagnetic flux measurement, although a good compensation of the vessel poloidal image current is crucial for ensuring a sufficiently large bandwidth to allow the use of high frequency modulation. The analysis of the behaviour of the amplitude and phase response in the modulation frequency scan has

Optical Path Length Calibration: A Standard Approach for Use in Absorption Cell-Based IR-Spectrometric Gas Analysis

Directory of Open Access Journals (Sweden)

Javis Anyangwe Nwaboh

2014-01-01

Full Text Available We employed a comparison method to determine the optical path length of gas cells which can be used in spectroscopic setup based on laser absorption spectroscopy or FTIR. The method is based on absorption spectroscopy itself. A reference gas cell, whose length is a priori known and desirably traceable to the international system of units (SI, and a gas mixture are used to calibrate the path length of a cell under test. By comparing spectra derived from pressure-dependent measurements on the two cells, the path length of the gas cell under test is determined. The method relies neither on the knowledge of the gas concentration nor on the line strength parameter of the probed transition which is very rarely traceable to the SI and of which the uncertainty is often relatively large. The method is flexible such that any infrared light source and infrared active molecule with isolated lines can be used. We elaborate on the method, substantiate the method by reporting results of this calibration procedure applied to multipass and single pass gas cells of lengths from 0.38 m to 21 m, and compare this to other methods. The relative combined uncertainty of the path length results determined using the comparison method was found to be in the ±0.4% range.

All-optical, thermo-optical path length modulation based on the vanadium-doped fibers.

Science.gov (United States)

Matjasec, Ziga; Campelj, Stanislav; Donlagic, Denis

2013-05-20

This paper presents an all-fiber, fully-optically controlled, optical-path length modulator based on highly absorbing optical fiber. The modulator utilizes a high-power 980 nm pump diode and a short section of vanadium-co-doped single mode fiber that is heated through absorption and a non-radiative relaxation process. The achievable path length modulation range primarily depends on the pump's power and the convective heat-transfer coefficient of the surrounding gas, while the time response primarily depends on the heated fiber's diameter. An absolute optical length change in excess of 500 µm and a time-constant as short as 11 ms, were demonstrated experimentally. The all-fiber design allows for an electrically-passive and remote operation of the modulator. The presented modulator could find use within various fiber-optics systems that require optical (remote) path length control or modulation.

Aerosol light absorption and its measurement: A review

International Nuclear Information System (INIS)

Moosmueller, H.; Chakrabarty, R.K.; Arnott, W.P.

2009-01-01

Light absorption by aerosols contributes to solar radiative forcing through absorption of solar radiation and heating of the absorbing aerosol layer. Besides the direct radiative effect, the heating can evaporate clouds and change the atmospheric dynamics. Aerosol light absorption in the atmosphere is dominated by black carbon (BC) with additional, significant contributions from the still poorly understood brown carbon and from mineral dust. Sources of these absorbing aerosols include biomass burning and other combustion processes and dust entrainment. For particles much smaller than the wavelength of incident light, absorption is proportional to the particle volume and mass. Absorption can be calculated with Mie theory for spherical particles and with more complicated numerical methods for other particle shapes. The quantitative measurement of aerosol light absorption is still a challenge. Simple, commonly used filter measurements are prone to measurement artifacts due to particle concentration and modification of particle and filter morphology upon particle deposition, optical interaction of deposited particles and filter medium, and poor angular integration of light scattered by deposited particles. In situ methods measure particle absorption with the particles in their natural suspended state and therefore are not prone to effects related to particle deposition and concentration on filters. Photoacoustic and refractive index-based measurements rely on the heating of particles during light absorption, which, for power-modulated light sources, causes an acoustic signal and modulation of the refractive index in the air surrounding the particles that can be quantified with a microphone and an interferometer, respectively. These methods may suffer from some interference due to light-induced particle evaporation. Laser-induced incandescence also monitors particle heating upon absorption, but heats absorbing particles to much higher temperatures to quantify BC mass

Ultrafast self-modulation of the optical absorption spectrum under conditions of both the ultrashort optical pumping and superluminescence in GaAs

International Nuclear Information System (INIS)

Ageeva, N. N.; Bronevoi, I. L.; Krivonosov, A. N.; Stegantsov, S. V.

2006-01-01

Self-modulation of the optical absorption spectrum is observed during the picosecond photogeneration of charge carriers and intense superluminescence in GaAs. As the picosecond delay τ of the probing pulse with respect to the pump pulse is varied in the region of τ < 0, the local points of the absorption intensification (juts) shift along the spectrum (the modulation resembles a running wave). As the value of τ is varied in the vicinity of τ = 0, the juts in the spectrum arise and disappear at approximately fixed photon energies (the modulation resembles a standing wave). At certain photon energies, the dependence of the rate of variation in the absorption coefficient dα/dτ on τ is found to be modulated by pulsations, similarly to the previously observed modulation of the picosecond stimulated emission from GaAs. Presumably, the spectrum self-modulation represents (and, thus, reveals) the modulation of the electron distribution in the conduction band. This modulation is caused by the fact that the evolution of the electron-population depletion at the bottom of the conduction band during superluminescence reflects (due to the electron-phonon interaction) on the population of the upper energy levels in the band

Microwave absorption studies of MgB 2 superconductor

Indian Academy of Sciences (India)

Microwave absorption studies have been carried out on MgB2 superconductor using a standard X-band EPR spectrometer. The modulated low-field microwave absorption signals recorded for polycrystalline (grain size ∼ 10m) samples suggested the absence of weak-link character. The field dependent direct microwave ...

Nonlinear intersubband absorption and refractive index changes in square and graded quantum well modulated by temperature and Hydrostatic pressure

International Nuclear Information System (INIS)

Ozturk, Emine; Sokmen, Ismail

2013-01-01

In this study, the effects of hydrostatic pressure and temperature on the linear and nonlinear intersubband transitions and the refractive index changes in the conduction band of square and graded quantum well (QW) are theoretically calculated within the framework of effective mass approximation. Results obtained show that the energy levels in different QWs and intersubband properties can be modified and controlled by the hydrostatic pressure and temperature. The modulation of the absorption coefficients and the refractive index changes which can be suitable for good performance optical modulators and various infrared optical device applications can be easily obtained by tuning the temperature and the hydrostatic pressure. - Highlights: ► Linear and nonlinear optical processes can be changed by pressure and temperature. ► Magnitude and energy of absorption peaks decrease as pressure increases. ► Refractive index changes in magnitude and energy decrease by increasing pressure. ► Energy differences are dependent on pressure, temperature and QW shapes. ► By increasing pressure we can obtain redshift in the optical transitions. ► For SQW, the absorption spectrum shows blueshift as the temperature increases. ► For GQW, the absorption spectrum shows redshift by temperature.

Direct and quantitative broadband absorptance spectroscopy with multilayer cantilever probes

Science.gov (United States)

Hsu, Wei-Chun; Tong, Jonathan Kien-Kwok; Liao, Bolin; Chen, Gang

2015-04-21

A system for measuring the absorption spectrum of a sample is provided that includes a broadband light source that produces broadband light defined within a range of an absorptance spectrum. An interferometer modulates the intensity of the broadband light source for a range of modulation frequencies. A bi-layer cantilever probe arm is thermally connected to a sample arm having at most two layers of materials. The broadband light modulated by the interferometer is directed towards the sample and absorbed by the sample and converted into heat, which causes a temperature rise and bending of the bi-layer cantilever probe arm. A detector mechanism measures and records the deflection of the probe arm so as to obtain the absorptance spectrum of the sample.

Exploring the origin of high optical absorption in conjugated polymers

KAUST Repository

Vezie, Michelle S.; Few, Sheridan; Meager, Iain; Pieridou, Galatia; Dö rling, Bernhard; Ashraf, Raja Shahid; Goñ i, Alejandro R.; Bronstein, Hugo; McCulloch, Iain; Hayes, Sophia C.; Campoy-Quiles, Mariano; Nelson, Jenny

2016-01-01

The specific optical absorption of an organic semiconductor is critical to the performance of organic optoelectronic devices. For example, higher light-harvesting efficiency can lead to higher photocurrent in solar cells that are limited by sub-optimal electrical transport. Here, we compare over 40 conjugated polymers, and find that many different chemical structures share an apparent maximum in their extinction coefficients. However, a diketopyrrolopyrrole-thienothiophene copolymer shows remarkably high optical absorption at relatively low photon energies. By investigating its backbone structure and conformation with measurements and quantum chemical calculations, we find that the high optical absorption can be explained by the high persistence length of the polymer. Accordingly, we demonstrate high absorption in other polymers with high theoretical persistence length. Visible light harvesting may be enhanced in other conjugated polymers through judicious design of the structure.

Exploring the origin of high optical absorption in conjugated polymers

KAUST Repository

Vezie, Michelle S.

2016-05-16

The specific optical absorption of an organic semiconductor is critical to the performance of organic optoelectronic devices. For example, higher light-harvesting efficiency can lead to higher photocurrent in solar cells that are limited by sub-optimal electrical transport. Here, we compare over 40 conjugated polymers, and find that many different chemical structures share an apparent maximum in their extinction coefficients. However, a diketopyrrolopyrrole-thienothiophene copolymer shows remarkably high optical absorption at relatively low photon energies. By investigating its backbone structure and conformation with measurements and quantum chemical calculations, we find that the high optical absorption can be explained by the high persistence length of the polymer. Accordingly, we demonstrate high absorption in other polymers with high theoretical persistence length. Visible light harvesting may be enhanced in other conjugated polymers through judicious design of the structure.

Multi-spectral optical absorption in substrate-free nanowire arrays

Energy Technology Data Exchange (ETDEWEB)

Zhang, Junpeng; Chia, Andrew; Boulanger, Jonathan; LaPierre, Ray, E-mail: lapierr@mcmaster.ca [Department of Engineering Physics, McMaster University, 1280 Main St. West, Hamilton, Ontario L8S 4L7 (Canada); Dhindsa, Navneet; Khodadad, Iman; Saini, Simarjeet [Department of Electrical and Computer Engineering, University of Waterloo, 200 University Ave West, Waterloo, Ontario N2L 3G1 (Canada); Waterloo Institute of Nanotechnology, University of Waterloo, 200 University Ave West, Waterloo, Ontario N2L 3G1 (Canada)

2014-09-22

A method is presented of fabricating gallium arsenide (GaAs) nanowire arrays of controlled diameter and period by reactive ion etching of a GaAs substrate containing an indium gallium arsenide (InGaP) etch stop layer, allowing the precise nanowire length to be controlled. The substrate is subsequently removed by selective etching, using the same InGaP etch stop layer, to create a substrate-free GaAs nanowire array. The optical absorptance of the nanowire array was then directly measured without absorption from a substrate. We directly observe absorptance spectra that can be tuned by the nanowire diameter, as explained with rigorous coupled wave analysis. These results illustrate strong optical absorption suitable for nanowire-based solar cells and multi-spectral absorption for wavelength discriminating photodetectors. The solar-weighted absorptance above the bandgap of GaAs was 94% for a nanowire surface coverage of only 15%.

Effect of idler absorption in pulsed optical parametric oscillators.

Science.gov (United States)

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.

Determination of hafnium by atomic absorption spectrometry

International Nuclear Information System (INIS)

Yoshida, Isao; Kobayashi, Hiroshi; Ueno, Keihei.

1977-01-01

Optimum conditions for atomic absorption spectrophotometric determination of hafnium were investigated by use of a Jarrel-Ash AA-1 instrument which was equipped with a premixed gas burner slotted 50 mm in length and 0.4 mm in width. Absorption of hafnium, which was atomized in an nitrous oxide-acetylene flame, was measured on a resonance line at 307.29 nm. The absorption due to hafnium was enhanced in the presence of ammonium fluoride and iron(III) ion, as shown in Figs. 2 and 3, depending on their concentration. The highest absorption was attained by the addition of (0.15 -- 0.3)M ammonium fluoride, 0.07 M of iron(III) ion and 0.05 M of hydrochloric acid. An excess of the additives decreased the absorption. The presence of zirconium, which caused a significant interference in the ordinary analytical methods, did not affect the absorption due to hafnium, if the zirconium concentration is less than 0.2 M. A standard procedure was proposed; A sample containing a few mg of hafnium was dissolved in a 25-ml volumetric flask, and ammonium fluoride, ferric nitrate and hydrochloric acid were added so that the final concentrations were 0.3, 0.07 and 0.05 M, respectively. Atomic absorption was measured on the aqueous solution in a nitrous oxide-acetylene flame and the hafnium content was calculated from the absorbance. Sensitivity was as high as 12.5 μg of Hf/ml/l% absorption. The present method is especially recommendable to the direct determination of hafnium in samples containing zirconium. (auth.)

Compact electro-absorption modulator integrated with vertical-cavity surface-emitting laser for highly efficient millimeter-wave modulation

International Nuclear Information System (INIS)

Dalir, Hamed; Ahmed, Moustafa; Bakry, Ahmed; Koyama, Fumio

2014-01-01

We demonstrate a compact electro-absorption slow-light modulator laterally-integrated with an 850 nm vertical-cavity surface-emitting laser (VCSEL), which enables highly efficient millimeter-wave modulation. We found a strong leaky travelling wave in the lateral direction between the two cavities via widening the waveguide width with a taper shape. The small signal response of the fabricated device shows a large enhancement of over 55 dB in the modulation amplitude at frequencies beyond 35 GHz; thanks to the photon-photon resonance. A large group index of over 150 in a Bragg reflector waveguide enables the resonance at millimeter wave frequencies for 25 μm long compact modulator. Based on the modeling, we expect a resonant modulation at a higher frequency of 70 GHz. The resonant modulation in a compact slow-light modulator plays a significant key role for high efficient narrow-band modulation in the millimeter wave range far beyond the intrinsic modulation bandwidth of VCSELs.

Absorption studies

International Nuclear Information System (INIS)

Ganatra, R.D.

1992-01-01

Absorption studies were once quite popular but hardly anyone does them these days. It is easier to estimate the blood level of the nutrient directly by radioimmunoassay (RIA). However, the information obtained by estimating the blood levels of the nutrients is not the same that can be obtained from the absorption studies. Absorption studies are primarily done to find out whether some of the essential nutrients are absorbed from the gut or not and if they are absorbed, to determine how much is being absorbed. In the advanced countries, these tests were mostly done to detect pernicious anaemia where vitamin B 12 is not absorbed because of the lack of the intrinsic factor in the stomach. In the tropical countries, ''malabsorption syndrome'' is quire common. In this condition, several nutrients like fat, folic acid and vitamin B 12 are not absorbed. It is possible to study absorption of these nutrients by radioisotopic absorption studies

Differential absorption lidar measurements of atmospheric water vapor using a pseudonoise code modulated AlGaAs laser. Thesis

Science.gov (United States)

Rall, Jonathan A. R.

1994-01-01

Lidar measurements using pseudonoise code modulated AlGaAs lasers are reported. Horizontal path lidar measurements were made at night to terrestrial targets at ranges of 5 and 13 km with 35 mW of average power and integration times of one second. Cloud and aerosol lidar measurements were made to thin cirrus clouds at 13 km altitude with Rayleigh (molecular) backscatter evident up to 9 km. Average transmitter power was 35 mW and measurement integration time was 20 minutes. An AlGaAs laser was used to characterize spectral properties of water vapor absorption lines at 811.617, 816.024, and 815.769 nm in a multipass absorption cell using derivative spectroscopy techniques. Frequency locking of an AlGaAs laser to a water vapor absorption line was achieved with a laser center frequency stability measured to better than one-fifth of the water vapor Doppler linewidth over several minutes. Differential absorption lidar measurements of atmospheric water vapor were made in both integrated path and range-resolved modes using an externally modulated AlGaAs laser. Mean water vapor number density was estimated from both integrated path and range-resolved DIAL measurements and agreed with measured humidity values to within 6.5 percent and 20 percent, respectively. Error sources were identified and their effects on estimates of water vapor number density calculated.

Absorption heat pumps

International Nuclear Information System (INIS)

Formigoni, C.

1998-01-01

A brief description of the difference between a compression and an absorption heat pump is made, and the reasons why absorption systems have spread lately are given. Studies and projects recently started in the field of absorption heat pumps, as well as criteria usually followed in project development are described. An outline (performance targets, basic components) of a project on a water/air absorption heat pump, running on natural gas or LPG, is given. The project was developed by the Robur Group as an evolution of a water absorption refrigerator operating with a water/ammonia solution, which has been on the market for a long time and recently innovated. Finally, a list of the main energy and cost advantages deriving from the use of absorption heat pumps is made [it

Parametric resonances in the amplitude-modulated probe-field absorption spectrum of a two-level atom driven by a resonance amplitude- and phase-modulated pumping field

International Nuclear Information System (INIS)

Sushilov, N.V.; Kholodkevich, E.D.

1995-01-01

An analytical expression is derived for the polarization induced by a weak probe field with periodically modulated amplitude in a two-level medium saturated by a strong amplitude-and phase-modulated resonance field. It is shown that the absorption spectrum of the probe field includes parametric resonances, the maxima corresponding to the condition δ= 2nΓ-Ω w and the minima to that of δ= (2n + 1)Γ- w , where δ is the probe-field detuning front the resonance frequency, Ω w is the modulation frequency of the probe-field amplitude, and Γ is the transition line width, n = 1, 2, 3, hor-ellipsis. At the specific modulation parameters, a substantial region of negative values (i.e., the region of amplification without the population inversion) exists in the absorption spectrum of the probe field

Quasar Absorption Studies

Science.gov (United States)

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.

Absorption of massive scalar field by a charged black hole

Energy Technology Data Exchange (ETDEWEB)

Nakamura, T [Kyoto Univ. (Japan). Dept. of Physics; Sato, H [Kyoto Univ. (Japan). Research Inst. for Fundamental Physics

1976-04-12

Absorption and reflection of charged, massive scalar field by the Reisner-Nordstrom black hole are investigated through a numerical computation. The absorption is suppressed when (Schwarzschild radius)<(Compton wave length) and the amplification of the wave occurs when the level crossing condition is satisfied.

Particle-in-a-box model of exciton absorption and electroabsorption in conjugated polymers

Science.gov (United States)

Pedersen, Thomas G.

2000-12-01

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

Reference-free determination of tissue absorption coefficient by modulation transfer function characterization in spatial frequency domain.

Science.gov (United States)

Chen, Weiting; Zhao, Huijuan; Li, Tongxin; Yan, Panpan; Zhao, Kuanxin; Qi, Caixia; Gao, Feng

2017-08-08

Spatial frequency domain (SFD) measurement allows rapid and non-contact wide-field imaging of the tissue optical properties, thus has become a potential tool for assessing physiological parameters and therapeutic responses during photodynamic therapy of skin diseases. The conventional SFD measurement requires a reference measurement within the same experimental scenario as that for a test one to calibrate mismatch between the real measurements and the model predictions. Due to the individual physical and geometrical differences among different tissues, organs and patients, an ideal reference measurement might be unavailable in clinical trials. To address this problem, we present a reference-free SFD determination of absorption coefficient that is based on the modulation transfer function (MTF) characterization. Instead of the absolute amplitude that is used in the conventional SFD approaches, we herein employ the MTF to characterize the propagation of the modulated lights in tissues. With such a dimensionless relative quantity, the measurements can be naturally corresponded to the model predictions without calibrating the illumination intensity. By constructing a three-dimensional database that portrays the MTF as a function of the optical properties (both the absorption coefficient μ a and the reduced scattering coefficient [Formula: see text]) and the spatial frequency, a look-up table approach or a least-square curve-fitting method is readily applied to recover the absorption coefficient from a single frequency or multiple frequencies, respectively. Simulation studies have verified the feasibility of the proposed reference-free method and evaluated its accuracy in the absorption recovery. Experimental validations have been performed on homogeneous tissue-mimicking phantoms with μ a ranging from 0.01 to 0.07 mm -1 and [Formula: see text] = 1.0 or 2.0 mm -1 . The results have shown maximum errors of 4.86 and 7% for [Formula: see text] = 1.0 mm -1 and

Absorption-Modulated Crossed-Optical Fiber-Sensor Platform for Measurements in Liquid Environments and Flow Streams

Directory of Open Access Journals (Sweden)

Paul E. Henning

2017-01-01

Full Text Available A new evanescent-wave fiber sensor is described that utilizes absorption-modulated luminescence (AML in combination with a crossed-fiber sensor platform. The luminescence signals of two crossed-fiber reference regions, placed on opposite sides of the stretch of fiber supporting the absorbance sensor, monitor the optical intensity in the fiber core. Evanescent absorption of the sensor reduces a portion of the excitation light and modulates the luminescence of the second reference region. The attenuation is determined from the luminescence intensity of both reference regions similar to the Beer-Lambert Law. The AML-Crossed-Fiber technique was demonstrated using the absorbance of the Zn(II-PAN2 complex at 555 nm. A linear response was obtained over a zinc(II concentration range of 0 to 20 μM (approximately 0 to 1.3 ppm. A nonlinear response was observed at higher zinc(II concentrations and was attributed to depletion of higher-order modes in the fiber. This was corroborated by the measured induced repopulation of these modes.

Calcium absorption and achlorhydria

International Nuclear Information System (INIS)

Recker, R.R.

1985-01-01

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

Water absorption length measurement with the ANTARES optical beacon system

International Nuclear Information System (INIS)

Yepes-Ramirez, Harold

2011-01-01

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

In situ gas temperature measurements by UV-absorption spectroscopy

DEFF Research Database (Denmark)

Fateev, Alexander; Clausen, Sønnik

2009-01-01

The absorption spectrum of the NO A(2)Sigma(+) uniform and stable gas temperatures over a 0.533 m path....... The accuracy of both methods is discussed. Validation of the classical Lambert-Beer law has been demonstrated at NO concentrations up to 500 ppm and gas temperatures up to 1,500 degrees C over an optical absorption path length of 0.533 m....

Review on absorption technology with emphasis on small capacity absorption machines

Directory of Open Access Journals (Sweden)

Labus Jerko M.

2013-01-01

Full Text Available The aim of this paper is to review the past achievements in the field of absorption systems, their potential and possible directions for future development. Various types of absorption systems and research on working fluids are discussed in detail. Among various applications, solar cooling and combined cooling, heating and power (CCHP are identified as two most promising applications for further development of absorption machines. Under the same framework, special attention is given to the small capacity absorption machines and their current status at the market. Although this technology looks promising, it is still in development and many issues are open. With respect to that fact, this paper covers all the relevant aspects for further development of small capacity absorption machines.

$J/\\psi$ Absorption in Heavy Ion Collisions

CERN Document Server

Maiani, Luciano; Polosa, Antonio; Riquer, V

2004-01-01

We present a new calculation of the pi-J/psi dissociation cross sections within the Constituent Quark-Meson Model recently introduced. To discuss the absorption of J/psi in heavy-ion collisions, we assume the J/psi to be produced inside a thermalized pion gas, as discussed by Bjorken, and introduce the corrections due to absorption by nuclear matter as well. We fit the absorption length of the J/psi to the data obtained at the CERN SPS by the NA50 Collaboration for Pb-Pb collisions. Collisions of lower centrality allow us to determine the temperature and the energy density of the pion gas. For both these quantities we find values close to those indicated by lattice gauge calculations for the transition to a quark-gluon plasma. A simple extrapolation to more central collisions, which takes into account the increase of the energy deposited due to the increased nucleon flux, fails to reproduce the break in J/psi absorption indicated by NA50, thus lending support to the idea that an unconfined quark-gluon phase m...

Folate absorption

International Nuclear Information System (INIS)

Baker, S.J.

1976-01-01

Folate is the generic term given to numerous compounds of pteroic acid with glutamic acid. Knowledge of absorption is limited because of the complexities introduced by the variety of compounds and because of the inadequacy of investigational methods. Two assay methods are in use, namely microbiological and radioactive. Techniques used to study absorption include measurement of urinary excretion, serum concentration, faecal excretion, intestinal perfusion, and haematological response. It is probably necessary to test absorption of both pteroylmonoglutamic acid and one or more polyglutamates, and such tests would be facilitated by availability of synthesized compounds labelled with radioactive tracers at specifically selected sites. (author)

Modulated microwave absorption spectra from Josephson junctions on a scratched niobium wire

International Nuclear Information System (INIS)

Rubins, R.S.; Hutton, S.L.; Ravindran, K.; Subbaraman, K.; Drumheller, J.E.

1997-01-01

Modulated microwave absorption (MMA) spectra from Josephson junction formations on a scratched Nb wire have been studied at 9.3 GHz and 4 K. The peak-to-peak separation, δH of the Josephson lines was found to vary linearly with P 1/2 , where P is the applied microwave power, in contrast to a recent interpretation of junction formation in pressed lead pieces by Rubins, Drumheller, and Trybula. The interpretation of the MMA data on Nb are given in terms of the theory of Vichery, Beuneu, and Lejay for superconducting loops containing weak links. copyright 1997 The American Physical Society

Thermodynamic performance optimization of the absorption-generation process in an absorption refrigeration cycle

International Nuclear Information System (INIS)

Chen, Yi; Han, Wei; Jin, Hongguang

2016-01-01

Highlights: • This paper proposes a new thermal compressor model with boost pressure ratio. • The proposed model is an effective way to optimize the absorption-generation process. • Boost pressure ratio is a key parameter in the proposed thermal compressor model. • The optimum boost pressure ratios for two typical refrigeration systems are obtained. - Abstract: The absorption refrigeration cycle is a basic cycle that establishes the systems for utilizing mid-low temperature heat sources. A new thermal compressor model with a key parameter of boost pressure ratio is proposed to optimize the absorption-generation process. The ultimate generation pressure and boost pressure ratio are used to represent the potential and operating conditions of the thermal compressor, respectively. Using the proposed thermal compressor model, the operation mechanism and requirements of the absorption refrigeration system and absorption-compression refrigeration system are elucidated. Furthermore, the two typical heat conversion systems are optimized based on the thermal compressor model. The optimum boost pressure ratios of the absorption refrigeration system and the absorption-compression refrigeration system are 0.5 and 0.75, respectively. For the absorption refrigeration system, the optimum generation temperature is 125.31 °C at the cooling water temperature of 30 °C, which is obtained by simple thermodynamic calculation. The optimized thermodynamic performance of the absorption-compression refrigeration system is 16.7% higher than that of the conventional absorption refrigeration system when the generation temperature is 100 °C. The thermal compressor model proposed in this paper is an effective method for simplifying the optimization of the thermodynamic systems involving an absorption-generation process.

Qualitative comparison of duplex Stirling and absorption refrigerators in domestic applications

Energy Technology Data Exchange (ETDEWEB)

Shao, H. [Global Cooling BV, Zutphen (Netherlands)

2000-07-01

A qualitative comparison has been carried out between the duplex Stirling and the absorption refrigerator for domestic applications. The duplex Stirling has many advantages over the absorption refrigerator on efficiency, modulation, suitability, operating costs, pollution reduction. Based on the state of the art of free-piston gas-bearing and linear-motor Stirling engines and coolers, it appears technically and economically feasible to develop the duplex Stirling to compete with the absorption refrigerator for heat-driven domestic refrigeration. (orig.)

Broadband solar absorption enhancement via periodic nanostructuring of electrodes.

KAUST Repository

Adachi, Michael M; Labelle, André J; Thon, Susanna M; Lan, Xinzheng; Hoogland, Sjoerd; Sargent, Edward H

2013-01-01

Solution processed colloidal quantum dot (CQD) solar cells have great potential for large area low-cost photovoltaics. However, light utilization remains low mainly due to the tradeoff between small carrier transport lengths and longer infrared photon absorption lengths. Here, we demonstrate a bottom-illuminated periodic nanostructured CQD solar cell that enhances broadband absorption without compromising charge extraction efficiency of the device. We use finite difference time domain (FDTD) simulations to study the nanostructure for implementation in a realistic device and then build proof-of-concept nanostructured solar cells, which exhibit a broadband absorption enhancement over the wavelength range of λ = 600 to 1,100 nm, leading to a 31% improvement in overall short-circuit current density compared to a planar device containing an approximately equal volume of active material. Remarkably, the improved current density is achieved using a light-absorber volume less than half that typically used in the best planar devices.

Broadband solar absorption enhancement via periodic nanostructuring of electrodes.

KAUST Repository

Adachi, Michael M

2013-10-14

Solution processed colloidal quantum dot (CQD) solar cells have great potential for large area low-cost photovoltaics. However, light utilization remains low mainly due to the tradeoff between small carrier transport lengths and longer infrared photon absorption lengths. Here, we demonstrate a bottom-illuminated periodic nanostructured CQD solar cell that enhances broadband absorption without compromising charge extraction efficiency of the device. We use finite difference time domain (FDTD) simulations to study the nanostructure for implementation in a realistic device and then build proof-of-concept nanostructured solar cells, which exhibit a broadband absorption enhancement over the wavelength range of λ = 600 to 1,100 nm, leading to a 31% improvement in overall short-circuit current density compared to a planar device containing an approximately equal volume of active material. Remarkably, the improved current density is achieved using a light-absorber volume less than half that typically used in the best planar devices.

Calcium absorption

International Nuclear Information System (INIS)

Carlmark, B.; Reizenstein, P.; Dudley, R.A.

1976-01-01

The methods most commonly used to measure the absorption and retention of orally administered calcium are reviewed. Nearly all make use of calcium radioisotopes. The magnitude of calcium absorption and retention depends upon the chemical form and amount of calcium administered, and the clinical and nutritional status of the subject; these influences are briefly surveyed. (author)

Wavelength modulation spectroscopy--digital detection of gas absorption harmonics based on Fourier analysis.

Science.gov (United States)

Mei, Liang; Svanberg, Sune

2015-03-20

This work presents a detailed study of the theoretical aspects of the Fourier analysis method, which has been utilized for gas absorption harmonic detection in wavelength modulation spectroscopy (WMS). The lock-in detection of the harmonic signal is accomplished by studying the phase term of the inverse Fourier transform of the Fourier spectrum that corresponds to the harmonic signal. The mathematics and the corresponding simulation results are given for each procedure when applying the Fourier analysis method. The present work provides a detailed view of the WMS technique when applying the Fourier analysis method.

Particulate absorption properties in the Red Sea from hyperspectral particulate absorption spectra

KAUST Repository

Tiwari, Surya Prakash

2018-03-16

This paper aims to describe the variability of particulate absorption properties using a unique hyperspectral dataset collected in the Red Sea as part of the TARA Oceans expedition. The absorption contributions by phytoplankton (aph) and non-algal particles (aNAP) to the total particulate absorption coefficients are determined using a numerical decomposition method (NDM). The NDM is validated by comparing the NDM derived values of aph and aNAP with simulated values of aph and aNAP are found to be in excellent agreement for the selected wavelengths (i.e., 443, 490, 555, and 676nm) with high correlation coefficient (R2), low root mean square error (RMSE), mean relative error (MRE), and with a slope close to unity. Further analyses showed that the total particulate absorption coefficients (i.e., ap(443)average = 0.01995m−1) were dominated by phytoplankton absorption (i.e., aph(443)average = 0.01743m−1) with a smaller contribution by non-algal particles absorption (i.e., aNAP(443)average = 0.002524m−1). The chlorophyll a is computed using the absorption based Line Height Method (LHM). The derived chlorophyll-specific absorption ((a⁎ph = aph(λ)/ChlLH)) showed more variability in the blue part of spectrum as compared to the red part of spectrum representative of the package effect and changes in pigment composition. A new parametrization proposed also enabled the reconstruction of a⁎ph(λ) for the Red Sea. Comparison of derived spectral constants with the spectral constants of existing models showed that our study A(λ) values are consistent with the existing values, despite there is a divergence with the B(λ) values. This study provides valuable information derived from the particulate absorption properties and its spectral variability and this would help us to determine the relationship between the phytoplankton absorption coefficients and chlorophyll a and its host of variables for the Red Sea.

Terahertz absorption and emission upon the photoionization of acceptors in uniaxially stressed silicon

Energy Technology Data Exchange (ETDEWEB)

Zhukavin, R. Kh., E-mail: zhur@ipmras.ru; Kovalevsky, K. A.; Orlov, M. L.; Tsyplenkov, V. V. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Hübers, H.-W. [DLR Institute of Optical Sensor Systems (Germany); Dessmann, N. [Humboldt University of Berlin, Institute of Physics (Germany); Kozlov, D. V.; Shastin, V. N. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation)

2016-11-15

Experimental data on the spontaneous emission and absorption modulation in boron-doped silicon under CO{sub 2} laser excitation depending on the uniaxial stress applied along the [001] and [011] crystallographic directions are presented. Room-temperature radiation is used as the probe radiation. Low stress (less than 0.5 kbar) is shown to reduce losses in the terahertz region by 20%. The main contribution to absorption modulation at zero and low stress is made by A{sup +} centers. Intersubband free hole transitions additionally contribute to terahertz absorption at higher stress. These contributions can be minimized by compensation.

Direct and quantitative photothermal absorption spectroscopy of individual particulates

International Nuclear Information System (INIS)

Tong, Jonathan K.; Hsu, Wei-Chun; Eon Han, Sang; Burg, Brian R.; Chen, Gang; Zheng, Ruiting; Shen, Sheng

2013-01-01

Photonic structures can exhibit significant absorption enhancement when an object's length scale is comparable to or smaller than the wavelength of light. This property has enabled photonic structures to be an integral component in many applications such as solar cells, light emitting diodes, and photothermal therapy. To characterize this enhancement at the single particulate level, conventional methods have consisted of indirect or qualitative approaches which are often limited to certain sample types. To overcome these limitations, we used a bilayer cantilever to directly and quantitatively measure the spectral absorption efficiency of a single silicon microwire in the visible wavelength range. We demonstrate an absorption enhancement on a per unit volume basis compared to a thin film, which shows good agreement with Mie theory calculations. This approach offers a quantitative approach for broadband absorption measurements on a wide range of photonic structures of different geometric and material compositions

Vitamin A absorption

International Nuclear Information System (INIS)

Baker, S.J.

1976-01-01

Investigation of the absorption of vitamin A and related substances is complicated by the multiplicity of forms in which they occur in the diet and by the possibility that they may be subject to different mechanisms of absorption. Present knowledge of these mechanisms is inadequate, especially in the case of carotenoids. Numerous tests of absorption have been developed. The most common has been the biochemical measurement of the rise in plasma vitamin A after an oral dose of retinol or retinyl ester, but standardization is inadequate. Radioisotope tests based upon assay of serum or faecal activity following oral administration of tritiated vitamin A derivaties hold considerable promise, but again standardization is inadequate. From investigations hitherto performed it is known that absorption of vitamin A is influenced by several diseases, although as yet the consistency of results and the correlation with other tests of intestinal function have often been poor. However, the test of vitamin A absorption is nevertheless of clinical importance as a specialized measure of intestinal function. (author)

D-xylose absorption

Science.gov (United States)

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

Polarization-Insensitive Surface Plasmon Polarization Electro-Absorption Modulator Based on Epsilon-Near-Zero Indium Tin Oxide

Science.gov (United States)

Jin, Lin; Wen, Long; Liang, Li; Chen, Qin; Sun, Yunfei

2018-02-01

CMOS-compatible plasmonic modulators operating at the telecom wavelength are significant for a variety of on-chip applications. Relying on the manipulation of the transverse magnetic (TM) mode excited on the metal-dielectric interface, most of the previous demonstrations are designed to response only for specific polarization state. In this case, it will lead to a high polarization dependent loss, when the polarization-sensitive modulator integrates to a fiber with random polarization state. Herein, we propose a plasmonic modulator utilizing a metal-oxide indium tin oxide (ITO) wrapped around the silicon waveguide and investigate its optical modulation ability for both the vertical and horizontal polarized guiding light by tuning electro-absorption of ITO with the field-induced carrier injection. The electrically biased modulator with electron accumulated at the ITO/oxide interface allows for epsilon-near-zero (ENZ) mode to be excited at the top or lateral portion of the interface depending on the polarization state of the guiding light. Because of the high localized feature of ENZ mode, efficient electro-absorption can be achieved under the "OFF" state of the device, thus leading to large extinction ratio (ER) for both polarizations in our proposed modulator. Further, the polarization-insensitive modulation is realized by properly tailoring the thickness of oxide in two different stacking directions and therefore matching the ER values for device operating at vertical and horizontal polarized modes. For the optimized geometry configuration, the difference between the ER values of two polarization modes, i.e., the ΔER, as small as 0.01 dB/μm is demonstrated and, simultaneously with coupling efficiency above 74%, is obtained for both polarizations at a wavelength of 1.55 μm. The proposed plasmonic-combined modulator has a potential application in guiding and processing of light from a fiber with a random polarization state.

A comparison of the modulated microwave absorption spectra of ceramic and powdered YBa2Cu3O7-δ samples

International Nuclear Information System (INIS)

Rubins, R.S.; Hutton, S.L.; Drumheller, J.E.; Jeong, D.Y.; Black, T.D.

1990-01-01

Flux trapping in the 9.3 GHz modulated microwave absorption spectra observed near 4 K from ceramic and powdered ceramic specimens of two separately prepared YBa 2 Cu 3 O 7-δ samples has been used to separate the intergranular and intragranular contributions to the spectra. In the denser, glassy sample, a broad absorption with a peak near 400 Oe for forward sweeps was observed with appreciable intensity after the maximum flux was trapped. This spectrum is attributed to intergranular junctions, since its relative intensity was reduced on powdering and suspending in wax. In the less dense, more uniform sample, the latter spectrum was appreciably weaker in both ceramic and powder. Both types of junction appear to contribute to the narrow low-field absorption which was observed after zero field cooling in all the samples

Techniques For Measuring Absorption Coefficients In Crystalline Materials

Science.gov (United States)

Klein, Philipp H.

1981-10-01

Absorption coefficients smaller than 0.001 cm-1 can, with more or less difficulty, be measured by several techniques. With diligence, all methods can be refined to permit measurement of absorption coefficients as small as 0.00001 cm-1. Spectral data are most readily obtained by transmission (spectrophotometric) methods, using multiple internal reflection to increase effective sample length. Emissivity measurements, requiring extreme care in the elimination of detector noise and stray light, nevertheless afford the most accessible spectral data in the 0.0001 to 0.00001 cm-1 range. Single-wavelength informa-tion is most readily obtained with modifications of laser calorimetry. Thermo-couple detection of energy absorbed from a laser beam is convenient, but involves dc amplification techniques and is susceptible to stray-light problems. Photoacoustic detection, using ac methods, tends to diminish errors of these types, but at some expense in experimental complexity. Laser calorimetry has been used for measurements of absorption coefficients as small as 0.000003 cm-1. Both transmission and calorimetric data, taken as functions of intensity, have been used for measurement of nonlinear absorption coefficients.

Sound absorption of a new oblique-section acoustic metamaterial with nested resonator

Science.gov (United States)

Gao, Nansha; Hou, Hong; Zhang, Yanni; Wu, Jiu Hui

2018-02-01

This study designs and investigates high-efficiency sound absorption of new oblique-section nested resonators. Impedance tube experiment results show that different combinations of oblique-section nest resonators have tunable low-frequency bandwidth characteristics. The sound absorption mechanism is due to air friction losses in the slotted region and the sample structure resonance. The acousto-electric analogy model demonstrates that the sound absorption peak and bandwidth can be modulated over an even wider frequency range by changing the geometric size and combinations of structures. The proposed structure can be easily fabricated and used in low-frequency sound absorption applications.

Frequency-chirped readout of spatial-spectral absorption features

International Nuclear Information System (INIS)

Chang, Tiejun; Mohan, R. Krishna; Harris, Todd L.; Merkel, Kristian D.; Tian Mingzhen; Babbitt, Wm. Randall

2004-01-01

This paper examines the physical mechanisms of reading out spatial-spectral absorption features in an inhomogeneously broadened medium using linear frequency-chirped electric fields. A Maxwell-Bloch model using numerical calculation for angled beams with arbitrary phase modulation is used to simulate the chirped field readout process. The simulation results indicate that any spatial-spectral absorption feature can be read out with a chirped field with the appropriate bandwidth, duration, and intensity. Mapping spectral absorption features into temporal intensity modulations depends on the chirp rate of the field. However, when probing a spatial-spectral grating with a chirped field, a beat signal representing the grating period can be created by interfering the emitted photon echo chirped field with a reference chirped field, regardless of the chirp rate. Comparisons are made between collinear and angled readout configurations. Readout signal strength and spurious signal distortions are investigated as functions of the grating strength and the Rabi frequency of the readout pulse. Using a collinear readout geometry, distortions from optical nutation on the transmitted field and higher-order harmonics are observed, both of which are avoided in an angled beam geometry

Modernization of Atomic Absorption Spectrophotometer

International Nuclear Information System (INIS)

Tasic, Visa; Milivojevic, Dragan; Karabasevic, Dejan

2003-01-01

In Copper Institute in Bor, connection has been made between absorption spectrophotometer and standard PC with the aim to make its operation more reliable and comfortable. Applied solution includes both software and hardware components. An I/O interface module has been installed in PC [1]. Software component consists of programs for measuring and interpretation of results. Paper presents details of this job realization.(Author)

Iron absorption by roots of fruit plants : some characteristics of the phenomena

International Nuclear Information System (INIS)

Bindra, A.S.

1979-01-01

Using young plants of peach, plum and almond growing in water culture, study was undertaken on the absorption and translocation of labelled iron. When peach plants deficient in this element were supplied with it, they tended to absorb it very rapidly, especially during the first 30 minutes. This absorption was not a superficial adsorption. Iron absorption was found to be linked to the length of non-lignified roots. Of the three species, almond absorbed more iron than peach but less than olum. No significant varietal difference was found regarding the iron absorption capacity of roots of different varieties of peach. Removal of foliage did not influence the absorption of iron by roots of peach plants in the early stages. (auth.)

Design of electro-absorption modulator with tapered-mode coupler on the GeSi layer

International Nuclear Information System (INIS)

Li, Ym; Cheng, Bw

2013-01-01

A tapered-mode coupler integrated GeSi electro-absorption (EA) modulator is investigated theoretically. To improve the parameter insensitivity and modulation efficiency of the GeSi EA modulator based on evanescent coupling, a tapered coupler on the GeSi layer is introduced in our design. The two coupling mechanisms in our suggested structure are compared. Both the beam propagation method (BPM) calculation and coupling mode theory show almost 100% power transfer from the bottom rib waveguide to the GeSi layer. After a series of designs of the tapered coupler, we get a modulator with the advantages of both evanescent-coupling modulators (Feng et al 2011 Opt. Express 19 7062–7, Feng et al 2012 Opt. Express 20 22224–32, Liu et al 2008 Nature Photon. 2 433–7, Liu et al 2007 Opt. Express 15 623–8) and butt-coupling modulators (Lim et al 2011 Opt. Express 19 5040–6), that are ease of fabrication, low coupling loss, performance stability and high modulation efficiency. (paper)

Investigation of 1.3 μm AlGaInAs multi-quantum wells for electro-absorption modulated laser

Energy Technology Data Exchange (ETDEWEB)

Binet, Guillaume [III-V Lab., Route de Nozay, 91461, Marcoussis (France); Institut Jean le Rond d' Alembert, Sorbonne Universites, UPMC Univ. Paris 06, CNRS, UMR 7190, 75005, Paris (France); Decobert, Jean; Lagay, Nadine; Chimot, Nicolas; Kazmierski, Christophe [III-V Lab., Route de Nozay, 91461, Marcoussis (France)

2016-10-15

Monolithic photonic integrated circuits (PIC) transmitters using the prefixed optical phase switching concept for BPSK modulation format have been shown promising at 1.55 μm band. These devices could also be crucial for short reach connections and access networks. With this aim, we are studying basic quantum well designs for a laser and an electro-absorption modulator switch to be integrated by selective area growth into PICs at 1.3 μm. Photocurrent measurements and band offset modeling have been performed to determine the MQW stack well-fitted for this application. Broad area laser measurements have also been checked on these structures to verify the material lasing properties. A 6 nm thick well with low barrier seems to be the best trade-off between absorption and shift for 1.3 μm EAM and it also gives good lasing properties. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

X-ray Absorption Spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Yano, Junko; Yachandra, Vittal K.

2009-07-09

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

Low voltage operation of electro-absorption modulator promising for high-definition 3D imaging application using a three step asymmetric coupled quantum well structure

International Nuclear Information System (INIS)

Na, Byung Hoon; Ju, Gun Wu; Cho, Yong Chul; Lee, Yong Tak; Choi, Hee Ju; Jeon, Jin Myeong; Lee, Soo Kyung; Park, Yong Hwa; Park, Chang Young

2015-01-01

In this paper, we propose a transmission type electro-absorption modulator (EAM) operating at 850 nm having low operating voltage and high absorption change with low insertion loss using a novel three step asymmetric coupled quantum well (3 ACQW) structure which can be used as an optical image shutter for high-definition (HD) three dimensional (3D) imaging. Theoretical calculations show that the exciton red shift of 3 ACQW structure is more than two times larger than that of rectangular quantum well (RQW) structure while maintaining high absorption change. The EAM having coupled cavities with 3 ACQW structure shows a wide spectral bandwidth and high amplitude modulation at a bias voltage of only -8V, which is 41% lower in operating voltage than that of RQW, making the proposed EAM highly attractive as an optical image shutter for HD 3D imaging applications

Absorption Spectroscopy in Hollow-Glass Waveguides Using Infrared Diode Lasers[4817-25

International Nuclear Information System (INIS)

Blake, Thomas A.; Kelly, James F.; Stewart, Timothy L.; Hartman, John S.; Sharpe, Steven W.; Sams, Robert L.; Alan Fried

2002-01-01

Near- and mid-infrared diode lasers combined with flexible, hollow waveguides hold the promise of light weight, field portable, fast response gas sensors. The advantages of using the waveguides compared to White or Herriott multireflection cells include a small gas volume, a high photon fill factor in the waveguide, which increases molecule-light interactions, and reduction or elimination of optical fringing, which usually sets the practical limit of detectivity in absorption spectroscopy. Though hollow waveguides have been commercially available for several years, relatively few results have been reported in the literature. We present here results from our laboratory where we have injected infrared laser light into straight and coiled lengths of hollow waveguides and performed direct and wavelength modulated absorption spectroscopy on nitrous oxide, ethylene, and nitric oxide. Using a 1 mm bore, 3 meter long coiled waveguide coated for the near infrared, nitrous oxide transitions near 6595 cm-1 were observed under flowing conditions. Signal-to-noise ratios on the order of 1500:1 with RMS noise equal to 2 X 10-5 were measured. In the mid-infrared light from either a 10.1 or 5.3 micron lead salt diode laser was injected into a three meter length of 1 mm bore hollow waveguide coated for the mid-infrared. The waveguide was coiled with one loop at a diameter of 52 cm. Ethylene transitions were observed in the vicinity of 985 cm-1 with a static fill of 0.2 Torr of pure ethylene in the waveguide and nitric oxide transitions were observed in the vicinity of 1906 cm-1 using either a flow or a static fill of 1 ppm NO in nitrogen. In direct absorption the NO transitions are observed to have a signal-to-noise of approximately 5:1 for transitions with absorbances on the order of 10-3. Using wavelength modulated techniques the signal-to-noise ratio improves at least an order of magnitude. These encouraging results indicate that waveguides can be used for in situ gas monitoring

Evaluation of mass absorption in LiBr flat-fan sheets

International Nuclear Information System (INIS)

Palacios, E.; Izquierdo, M.; Marcos, J.D.; Lizarte, R.

2009-01-01

Experiments were conducted to determine the absorption rates of refrigerant vapour in an aqueous lithium bromide flat-fan sheet for use in absorption air-conditioning systems. The solution flow rates tested ranged from 0.023 to 0.054 kg/s (84-194 kg/h), with pressure losses in the injection nozzle of from 40 to 250 kPa. The effect of the mass flow rate on both solution residence time and the sheet deformation rate was also analyzed in absorption chambers of a pre-defined length, along with the effect of the sub-cooling temperature on the amount of vapour absorbed. The downstream evolution of approach to equilibrium factor F was quantified. The mass transfer coefficient values were found to be over 3 x 10 -4 m/s. In absorption chambers 100 mm long, over 0.8 g/s l of vapour were absorbed per chamber absorption volume. Moreover, about 600 g of vapour were absorbed per kJ of solution flow work. Flat-fan sheet configurations were found to perform better than falling film and spray absorbers.

Absorption and excretion tests

International Nuclear Information System (INIS)

Berberich, R.

1988-01-01

The absorption and excretion of radiopharmaceuticals is still of interest in diagnostic investigations of nuclear medicine. In this paper the most common methods of measuring absorption and excretion are described. The performance of the different tests and their standard values are discussed. More over the basic possibilities of measuring absorption and excretion including the needed measurement equipments are presented. (orig.) [de

Total photon absorption

International Nuclear Information System (INIS)

Carlos, P.

1985-06-01

The present discussion is limited to a presentation of the most recent total photonuclear absorption experiments performed with real photons at intermediate energy, and more precisely in the region of nucleon resonances. The main sources of real photons are briefly reviewed and the experimental procedures used for total photonuclear absorption cross section measurements. The main results obtained below 140 MeV photon energy as well as above 2 GeV are recalled. The experimental study of total photonuclear absorption in the nuclear resonance region (140 MeV< E<2 GeV) is still at its beginning and some results are presented

Microwave absorption across Tc: Determination of the angular dependance Hc2(theta)

OpenAIRE

Shaltiel, David; Bill, Hans; Grayevsky, A.; Junod, Alain; Lovy, Dominique; Sadowski, Wojciech; Walker, Eric

1991-01-01

It is shown that measuring microwave absorption in high-Tc superconductors at constant and very low magnetic fields, using magnetic-field modulation, is, under some conditions, equivalent to temperature modulation when sweeping the temperature across Tc. Using an ESR spectrometer, the derivative of microwave absorption is measured close to Tc. This allows a determination of the relative angular variation of dHc2/dT at T=Tc in single crystals of Y-Ba-Cu-O. The data fit the Ginzburg-Landau theo...

A structural study of ceramic oxides by X-ray absorption spectroscopy

International Nuclear Information System (INIS)

Akhtar, M.J.

1995-01-01

A detailed structural study of ceramic oxides is presented by employing X-ray Absorption Spectroscopy (XAS). In the present work X-ray Absorption Near Edge Structure (XANES) is used for the investigation of valence state of metal cations; whereas, Extended X-ray Absorption Fine Structure EXAFS) is employed for the determination for bond lengths, coordination numbers and nature of the elements present in the near neighbour shells surrounding the absorbing atom. These results show that local environment of dopant and host cations are different; and this variation in local structure depends on the nature and concentration of the dopant ions. (author)

Temperature-insensitive laser frequency locking near absorption lines

International Nuclear Information System (INIS)

Kostinski, Natalie; Olsen, Ben A.; Marsland, Robert III; McGuyer, Bart H.; Happer, William

2011-01-01

Combined magnetically induced circular dichroism and Faraday rotation of an atomic vapor are used to develop a variant of the dichroic atomic vapor laser lock that eliminates lock sensitivity to temperature fluctuations of the cell. Operating conditions that eliminate first-order sensitivity to temperature fluctuations can be determined by low-frequency temperature modulation. This temperature-insensitive gyrotropic laser lock can be accurately understood with a simple model, that is in excellent agreement with observations in potassium vapor at laser frequencies in a 2 GHz range about the 770.1 nm absorption line. The methods can be readily adapted for other absorption lines.

Subgap absorption in conjugated polymers

Energy Technology Data Exchange (ETDEWEB)

Sinclair, M.; Seager, C.H. (Sandia National Labs., Albuquerque, NM (USA)); McBranch, D.; Heeger, A.J. (California Univ., Santa Barbara, CA (USA)); Baker, G.L. (Bell Communications Research, Inc., Red Bank, NJ (USA))

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. 11 refs., 4 figs.

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

Science.gov (United States)

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.

Magnetically modulated microwave absorption (MMMA) measurements at low magnetic fields on the ferromagnetic state of [TDAE]C60

International Nuclear Information System (INIS)

Bele, P.; Brunner, H.

1997-01-01

The ferromagnetic state and reported superconductivity of [TDAE]C 60 (where TDAE is tetrakis(dimethylamino)ethylene) are investigated by magnetically modulated microwave absorption (MMMA). The results are compared with those reported using alternative physical measurement techniques, and a hypothesis proposed to explain the observed behavior. No evidence for superconductivity is found. (orig.)

A method of reducing background fluctuation in tunable diode laser absorption spectroscopy

Science.gov (United States)

Yang, Rendi; Dong, Xiaozhou; Bi, Yunfeng; Lv, Tieliang

2018-03-01

Optical interference fringe is the main factor that leads to background fluctuation in gas concentration detection based on tunable diode laser absorption spectroscopy. The interference fringes are generated by multiple reflections or scatterings upon optical surfaces in optical path and make the background signal present an approximated sinusoidal oscillation. To reduce the fluctuation of the background, a method that combines dual tone modulation (DTM) with vibration reflector (VR) is proposed in this paper. The combination of DTM and VR can make the unwanted periodic interference fringes to be averaged out and the effectiveness of the method in reducing background fluctuation has been verified by simulation and real experiments in this paper. In the detection system based on the proposed method, the standard deviation (STD) value of the background signal is decreased to 0.0924 parts per million (ppm), which is reduced by a factor of 16 compared with that of wavelength modulation spectroscopy. The STD value of 0.0924 ppm corresponds to the absorption of 4 . 328 × 10-6Hz - 1 / 2 (with effective optical path length of 4 m and integral time of 0.1 s). Moreover, the proposed method presents a better stable performance in reducing background fluctuation in long time experiments.

Nonlinear Cyclotron absorption of a hole doppleron in cadmium

Energy Technology Data Exchange (ETDEWEB)

Voloshin, I.F.; Bugal' ter, G.A.; Demikhovskii, V.Y.; Fisher, L.M.; Yudin, V.A.

1977-10-01

We investigated experimentally the nonlinear behavior of the impedance of a cadmium plate in the region of existence of the hole doppleron. It is shown theoretically that this phenomenon can be attributed to nonlinear cyclotron absorption of the wave in the metal. A theory of nonlinear cyclotron absorption of a hole doppleron in cadmium is constructed. The nonlinearity is due to the influence of the wave magnetic field H that alters the trajectories of the resonant electrons responsible for the cyclotron asorption. The Lorentz force connected with the field H modulates the particle velocity along the magnetic field at a characteristic frequency ..omega../sub 0/ proportional to the square root of the wave amplitude. The modulation of the longitudinal particle velocity leads to violation of the condition of their resonant interaction with the wave, as a result of which the absorption coefficient decreases. The nonlinearity is significant when the frequency ..omega../sub 0/ is large compared with the electron-collision frequency. A decrease of the cyclotron absorption changes radically the picture of the surface-impedance oscillations of the plate in the magnetic field. We studied in the experiment the influence of the temperature, of the angle of inclination of the magnetic field, and of the frequency on the nonlinear-effect threshold field that separates the regions of linear and nonlinear behavior of the sample impedance. The measurement results are in qualitative agreement with the conclusions of the theory.

Subgap Absorption in Conjugated Polymers

Science.gov (United States)

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

1991-01-01

Along with X{sup (3)}, the magnitude of the optical absorption in the transparent window below the principal absorption edge is an important parameter which will ultimately determine the utility of conjugated polymers in active integrated optical devices. With an absorptance sensitivity of 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.

Laser radiation short pulse absorption in a high-density plasma

International Nuclear Information System (INIS)

Brantov, A.V.; Bychenkov, V.Yu.; Tikhonchuk, V.T.

1998-01-01

Dependences of the absorption coefficients for s and p polarized electromagnetic waves (laser radiation) in a semi-bound plasma on the temperature and incidence angle are found for an arbitrary ratio of the skin-layer depth to the electron free path length t. The dependences obtained describe transition from the normal skin effect to abnormal one and permit quantitatively to determine the absorption coefficients in the intermediate range of the parameter t, characteristic for the majority of modern experiments

Geospatial Absorption and Regional Effects

Directory of Open Access Journals (Sweden)

IOAN MAC

2009-01-01

Full Text Available The geospatial absorptions are characterized by a specific complexity both in content and in their phenomenological and spatial manifestation fields. Such processes are differentiated according to their specificity to pre-absorption, absorption or post-absorption. The mechanisms that contribute to absorption are extremely numerous: aggregation, extension, diffusion, substitution, resistivity (resilience, stratification, borrowings, etc. Between these mechanisms frequent relations are established determining an amplification of the process and of its regional effects. The installation of the geographic osmosis phenomenon in a given territory (a place for example leads to a homogenization of the geospatial state and to the installation of the regional homogeneity.

Particulate absorption properties in the Red Sea from hyperspectral particulate absorption spectra

KAUST Repository

Tiwari, Surya Prakash; Zarokanellos, Nikolaos; Kheireddine, Malika; Shanmugam, Palanisamy; Jones, Burton

2018-01-01

This paper aims to describe the variability of particulate absorption properties using a unique hyperspectral dataset collected in the Red Sea as part of the TARA Oceans expedition. The absorption contributions by phytoplankton (aph) and non

In operando observation system for electrochemical reaction by soft X-ray absorption spectroscopy with potential modulation method

International Nuclear Information System (INIS)

Nagasaka, Masanari; Kosugi, Nobuhiro; Yuzawa, Hayato; Horigome, Toshio

2014-01-01

In order to investigate local structures of electrolytes in electrochemical reactions under the same scan rate as a typical value 100 mV/s in cyclic voltammetry (CV), we have developed an in operando observation system for electrochemical reactions by soft X-ray absorption spectroscopy (XAS) with a potential modulation method. XAS spectra of electrolytes are measured by using a transmission-type liquid flow cell with built-in electrodes. The electrode potential is swept with a scan rate of 100 mV/s at a fixed photon energy, and soft X-ray absorption coefficients at different potentials are measured at the same time. By repeating the potential modulation at each fixed photon energy, it is possible to measure XAS of electrochemical reaction at the same scan rate as in CV. We have demonstrated successful measurement of the Fe L-edge XAS spectra of aqueous iron sulfate solutions and of the change in valence of Fe ions at different potentials in the Fe redox reaction. The mechanism of these Fe redox processes is discussed by correlating the XAS results with those at different scan rates

Analysis of Hybrid-Integrated High-Speed Electro-Absorption Modulated Lasers Based on EM/Circuit Co-simulation

DEFF Research Database (Denmark)

Johansen, Tom Keinicke; Krozer, Viktor; Kazmierski, C.

2009-01-01

An improved electromagnetic simulation (EM) based approach has been developed for optimization of the electrical to optical (E/O) transmission properties of integrated electro-absorption modulated lasers (EMLs) aiming at 100 Gbit/s Ethernet applications. Our approach allows for an accurate analysis...... of the EML performance in a hybrid microstrip assembly. The established EM-based approach provides a design methodology for the future hybrid integration of the EML with its driving electronics....

Spectroscopic method for determination of the absorption coefficient in brain tissue

Science.gov (United States)

Johansson, Johannes D.

2010-09-01

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

[Signal analysis and spectrum distortion correction for tunable diode laser absorption spectroscopy system].

Science.gov (United States)

Bao, Wei-Yi; Zhu, Yong; Chen, Jun; Chen, Jun-Qing; Liang, Bo

2011-04-01

In the present paper, the signal of a tunable diode laser absorption spectroscopy (TDLAS) trace gas sensing system, which has a wavelength modulation with a wide range of modulation amplitudes, is studied based on Fourier analysis method. Theory explanation of spectrum distortion induced by laser intensity amplitude modulation is given. In order to rectify the spectrum distortion, a method of synchronous amplitude modulation suppression by a variable optical attenuator is proposed. To validate the method, an experimental setup is designed. Absorption spectrum measurement experiments on CO2 gas were carried out. The results show that the residual laser intensity modulation amplitude of the experimental system is reduced to -0.1% of its original value and the spectrum distortion improvement is 92% with the synchronous amplitude modulation suppression. The modulation amplitude of laser intensity can be effectively reduced and the spectrum distortion can be well corrected by using the given correction method and system. By using a variable optical attenuator in the TDLAS (tunable diode laser absorption spectroscopy) system, the dynamic range requirements of photoelectric detector, digital to analog converter, filters and other aspects of the TDLAS system are reduced. This spectrum distortion correction method can be used for online trace gas analyzing in process industry.

THz Electro-absorption Effect in Quantum Dots

DEFF Research Database (Denmark)

Turchinovich, Dmitry; Monozon, Boris S.; Livshits, Daniil A.

2011-01-01

In a THz pump - optical probe experiment we demonstrate an instantaneous electro-absorption effect in InGaAs/GaAs quantum dots, induced by the electric field of a single-cycle THz pulse with 3 THz bandwidth and with free-space peak electric field reaching 220 kV/cm. The transient modulation of QD...

Scramjet Performance Assessment Using Water Absorption Diagnostics (U)

Science.gov (United States)

Cavolowsky, John A.; Loomis, Mark P.; Deiwert, George

1995-01-01

Simultaneous multiple path measurements of temperature and H2O concentration will be presented for the AIMHYE test entries in the NASA Ames 16-Inch Shock Tunnel. Monitoring the progress of high temperature chemical reactions that define scramjet combustor efficiencies is a task uniquely suited to nonintrusive optical diagnostics. One application strategy to overcome the many challenges and limitations of nonintrusive measurements is to use laser absorption spectroscopy coupled with optical fibers. Absorption spectroscopic techniques with rapidly tunable lasers are capable of making simultaneous measurements of mole fraction, temperature, pressure, and velocity. The scramjet water absorption diagnostic was used to measure combustor efficiency and was compared to thrust measurements using a nozzle force balance and integrated nozzle pressures to develop a direct technique for evaluating integrated scramjet performance. Tests were initially performed with a diode laser tuning over a water absorption feature at 1391.7 nm. A second diode laser later became available at a wavelength near 1343.3 nm covering an additional water absorption feature and was incorporated in the system for a two-wavelength technique. Both temperature and mole fraction can be inferred from the lineshape analysis using this approach. Additional high temperature spectroscopy research was conducted to reduce uncertainties in the scramjet application. The lasers are optical fiber coupled to ports at the combustor exit and in the nozzle region. The output from the two diode lasers were combined in a single fiber, and the resultant two-wavelength beam was subsequently split into four legs. Each leg was directed through 60 meters of optical fiber to four combustor exit locations for measurement of beam intensity after absorption by the water within the flow. Absorption results will be compared to 1D combustor analysis using RJPA and nozzle CFD computations as well as to data from a nozzle metric

Multifunctional hybrids for electromagnetic absorption

International Nuclear Information System (INIS)

Huynen, I.; Quievy, N.; Bailly, C.; Bollen, P.; Detrembleur, C.; Eggermont, S.; Molenberg, I.; Thomassin, J.M.; Urbanczyk, L.

2011-01-01

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

Free-Free Absorption on Parsec Scales in Seyfert Galaxies

Science.gov (United States)

Roy, A. L.; Ulvestad, J. S.; Wilson, A. S.; Colbert, E. J. M.; Mundell, C. G.; Wrobel, J. M.; Norris, R. P.; Falcke, H.; Krichbaum, T.

Seyfert galaxies come in two main types (types 1 and 2) and the difference is probably due to obscuration of the nucleus by a torus of dense molecular material. The inner edge of the torus is expected to be ionized by optical and ultraviolet emission from the active nucleus, and will radiate direct thermal emission (e.g. NGC 1068) and will cause free-free absorption of nuclear radio components viewed through the torus (e.g. Mrk 231, Mrk 348, NGC 2639). However, the nuclear radio sources in Seyfert galaxies are weak compared to radio galaxies and quasars, demanding high sensitivity to study these effects. We have been making sensitive phase referenced VLBI observations at wavelengths between 21 and 2 cm where the free-free turnover is expected, looking for parsec-scale absorption and emission. We find that free-free absorption is common (e.g. in Mrk 348, Mrk 231, NGC 2639, NGC 1068) although compact jets are still visible, and the inferred density of the absorber agrees with the absorption columns inferred from X-ray spectra (Mrk 231, Mrk 348, NGC 2639). We find one-sided parsec-scale jets in Mrk 348 and Mrk 231, and we measure low jet speeds (typically £ 0.1 c). The one-sidedness probably is not due to Doppler boosting, but rather is probably free-free absorption. Plasma density required to produce the absorption is Ne 3 2 105 cm-3 assuming a path length of 0.1 pc, typical of that expected at the inner edge of the obscuring torus.

The absorption of carbon monoxide in COSORB solutions: absorption rate and capacity

NARCIS (Netherlands)

Hogendoorn, Kees; van Swaaij, Willibrordus Petrus Maria; Versteeg, Geert

1995-01-01

Absorption rate experiments and equilibrium experiments were carried out for the COSORB reaction at 300 K. The equilibrium data at 300 K could reasonably well be described with the following relation: [...] Determination of the kinetics and mechanism of a chemical reaction by means of absorption

Customization of biliopancreatic limb length to modulate and sustain antidiabetic effect of gastric bypass surgery.

Science.gov (United States)

Pal, A; Rhoads, D B; Tavakkoli, A

2018-02-01

Although Roux-en-Y Gastric Bypass (RYGB) remains the most effective treatment for obesity and type 2 diabetes (T2D), many patients fail to achieve remission, or relapse. Increasing intestinal limb lengths of RYGB may improve outcomes, but the mechanistic basis for this remains unclear. We hypothesize biliopancreatic (BP) limb length modulates the antidiabetic effect of RYGB. Rats underwent RYGB with a 20-cm (RYGB-20cm) or 40-cm (RYGB-40cm) BP limb and were compared with control animals. After 2 and 4 wk, portal and systemic blood was sampled during intestinal glucose infusion. Portosystemic gradient was used to calculate intestinal glucose utilization (G util ), absorption (G absorp ), and hormone secretion. Intestinal morphology and gene expression were assessed. At 2 wk, G absorp progressively decreased with increasing BP limb length; this pattern persisted at 4 wk. G util increased ≈70% in both RYGB-20cm and -40cm groups at 2 wk. At 4 wk, G util progressively increased with limb length. Furthermore, Roux limb weight, and expression of hexokinase and preproglucagon, exhibited a similar progressive increase. At 4 wk, glucagon-like peptide-1 and -2 levels were higher after RYGB-40cm, with associated increased secretion. We conclude that BP limb length modulates multiple antidiabetic mechanisms, analogous to the dose-response relationship of a drug. Early postoperatively, a longer BP limb reduces G absorp . Later, G util , Roux limb hypertrophy, hormone secretion, and hormone levels are increased with longer BP limb. Sustained high incretin levels may prevent weight regain and T2D relapse. These data provide the basis for customizing BP limb length according to patient characteristics and desired metabolic effect. NEW & NOTEWORTHY Biliopancreatic limb length in gastric bypass modulates multiple antidiabetic mechanisms, analogous to the dose-response relationship of a drug. With a longer biliopancreatic limb, Roux limb hypertrophy, increased glucose utilization

Microwave absorption studies of MgB2 superconductor

Indian Academy of Sciences (India)

band (9–. 10 GHz) spectrometer. Both polycrystalline pellet and single-grain MgB2, having nearly the same Tc (∼ 39 K) and same size (3×2×1 mm3), were used in the present investigations. Low field modulated microwave absorption signals ...

Continuous registration of optical absorption spectra of periodically produced solvated electrons

International Nuclear Information System (INIS)

Krebs, P.

1975-01-01

Absorption spectra of unstable intermediates, such as solvated electrons, were usually taken point by point, recording the time-dependent light absorption after their production by a flash. The experimental arrangement for continuous recording of the spectra consists of a conventional one beam spectral photometer with a stabilized white light source, a monochromator, and a light detector. By periodic production of light absorbing intermediates such as solvated electrons, e.g., by ac uv light, a small ac signal is modulated on the light detector output which after amplification can be continuously recorded as a function of wavelength. This method allows the detection of absorption spectra when disturbances from the outside provide a signal-to-noise ratio smaller than 1

Uranium absorption study pile

International Nuclear Information System (INIS)

Raievski, V.; Sautiez, B.

1959-01-01

The report describes a pile designed to measure the absorption of fuel slugs. The pile is of graphite and comprises a central section composed of uranium rods in a regular lattice. RaBe sources and BF 3 counters are situated on either side of the center. A given uranium charge is compared with a specimen charge of about 560 kg, and the difference in absorption between the two noted. The sensitivity of the equipment will detect absorption variations of about a few ppm boron (10 -6 boron per gr. of uranium) or better. (author) [fr

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

Science.gov (United States)

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.

Linear photophysics, two-photon absorption and femtosecond transient absorption spectroscopy of styryl dye bases

Energy Technology Data Exchange (ETDEWEB)

Shaydyuk, Ye.O. [Institute of Physics, Prospect Nauki, 46, Kyiv-28 03028 Ukraine (Ukraine); Levchenko, S.M. [Institute of Molecular Biology and Genetics, 150, Akademika Zabolotnoho Str., Kyiv 036803 (Ukraine); Kurhuzenkau, S.A. [Department of Chemistry, University of Parma, Parco Area delle Scienze 17/A, Parma 43124 (Italy); Anderson, D. [NanoScienece Technology Center, University of Central Florida, 12424 Research Parkway, PAV400, Orlando, FL 32826 (United States); Department of Chemistry, University of Central Florida, 4111 Libra Drive, PSB225, Orlando, FL 32816 (United States); Masunov, A.E. [NanoScienece Technology Center, University of Central Florida, 12424 Research Parkway, PAV400, Orlando, FL 32826 (United States); Department of Chemistry, University of Central Florida, 4111 Libra Drive, PSB225, Orlando, FL 32816 (United States); South Ural State University, Lenin pr. 76, Chelyabinsk 454080 (Russian Federation); Department of Condensed Matter Physics, National Research Nuclear University MEPhI, Kashirskoye shosse 31, Moscow 115409 (Russian Federation); Photochemistry Center RAS, ul. Novatorov 7a, Moscow 119421 (Russian Federation); Kachkovsky, O.D.; Slominsky, Yu.L.; Bricks, J.L. [Insitute of Organic Chemistry, Murmanskaya Street, 5, Kyiv 03094 (Ukraine); Belfield, K.D. [College of Science and Liberal Arts, New Jersey Institute of Technology, University Heights, Newark, NJ 07102 (United States); School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi’an, 710062 (China); Bondar, M.V., E-mail: mbondar@mail.ucf.edu [Institute of Physics, Prospect Nauki, 46, Kyiv-28 03028 Ukraine (Ukraine)

2017-03-15

The steady-state and time-resolved linear spectral properties, two-photon absorption spectra and fast relaxation processes in the excited states of styryl base-type derivatives were investigated. The nature of linear absorption, fluorescence and excitation anisotropy spectra were analyzed in solvents of different polarity at room temperature and specific dependence of the solvatochromic behavior on the donor-acceptor strength of the terminal substituents was shown. Two-photon absorption (2PA) efficiency of styryl dye bases was determined in a broad spectral range using two-photon induced fluorescence technique, and cross-sections maxima of ~ 100 GM were found. The excited state absorption (ESA) and fast relaxation processes in the molecular structures were investigated by transient absorption femtosecond pump-probe methodology. The role of twisted intramolecular charge transfer (TICT) effect in the excited state of styryl dye base with dimethylamino substituent was shown. The experimental spectroscopic data were also verified by quantum chemical calculations at the Time Dependent Density Functional Theory level, combined with a polarizable continuum model.

Iron absorption in relation to iron status

International Nuclear Information System (INIS)

Magnusson, B.; Bjoern-Rasmussen, E.; Hallberg, L.; Rossander, L.

1981-01-01

The absorption from a 3 mg dose of ferrous iron was measured in 250 male subjects. The absorption was related to the log concentration of serum ferritin in 186 subjects of whom 99 were regular blood donors (r= -0.76), and to bone marrow haemosiderin grading in 52 subjects with varying iron status. The purpose was to try and establish a percentage absorption from such a dose that is representative of subjects who are borderline iron deficient. This information is necessary for food iron absorption studies in order (1) to calculate the absorption of iron from the diet at a given iron status and (2) compare the absorption of iron from different meals studied in different groups of subjects by different investigarors. The results suggest that an absorption of about 40% of a 3 mg reference dose of ferrous iron is given in a fasting state, roughly corresponds to the absorption in borderline-iron-deficient subjects. The results indicate that this 40% absorption value corresponds to a serum ferritin level of 30 μg/l and that food iron absorption in a group of subjects should be expressed preferably as the absorption corresponding to a reference-dose absorption of 45%, or possibly a serum ferritin level of 30 μg/l. (author)

Nutrition and magnesium absorption

NARCIS (Netherlands)

Brink, E.J.

1992-01-01

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

Active feedback regulation of a Michelson interferometer to achieve zero-background absorption measurements.

Science.gov (United States)

Lundin, Patrik; Guan, Zuguang; Svanberg, Sune

2011-01-20

An active phase-controlling scheme based on a proportional-integral-derivative-controlled piezoelectric transducer is presented with the purpose of stabilizing a quasi-zero-background absorption spectrometer. A fiber-based balanced Michelson interferometer is used, and absorption due to a gas sample in one of its arms results in an increased light signal to a detector, which otherwise, thanks to destructive interference, experiences a very low light level. With the presented approach, the sensitivity of already potent absorption measurement techniques, e.g., based on modulation, could be improved even further.

Uranium absorption study pile; Empilement pour le controle de l'absorption de l'uranium

Energy Technology Data Exchange (ETDEWEB)

Raievski, V; Sautiez, B [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

1959-07-01

The report describes a pile designed to measure the absorption of fuel slugs. The pile is of graphite and comprises a central section composed of uranium rods in a regular lattice. RaBe sources and BF{sub 3} counters are situated on either side of the center. A given uranium charge is compared with a specimen charge of about 560 kg, and the difference in absorption between the two noted. The sensitivity of the equipment will detect absorption variations of about a few ppm boron (10{sup -6} boron per gr. of uranium) or better. (author) [French] Nous decrivons un dispositif permettant de mesurer l'absorption des elements combustibles d'une pile. Ce dispositif est constitue par un empilement de graphite dont la region centrale est formee par un reseau regulier de barres d'uranium. Des sources de RaBe et des compteurs a BF{sub 3} sont places de part et d'autre de cette region. En comparant un chargement d'uranium a un chargement etalon d'environ 560 kg, on peut determiner la difference d'absorption entre ces deux chargements. La sensibilite permettrait de deceler une variation d'absorption de l'ordre du ppm de bore (10{sup -6} g de bore par gramme d'uranium) et peut-etre mieux. (auteur)

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

Science.gov (United States)

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

Evidence of In Vivo Absorption of Lactate and Modulation of Short Chain Fatty Acid Absorption from the Reticulorumen of Non-Lactating Cattle Fed High Concentrate Diets.

Directory of Open Access Journals (Sweden)

Muhammad Qumar

Full Text Available Short-chain fatty acids (SCFAs and lactate are endproducts of rumen fermentation and important energy sources for the host ruminant. Because their rapid accumulation results in ruminal acidosis, enhancement of the absorption of SCFA and lactate across reticuloruminal wall is instrumental in increasing energy supply and preventing ruminal acidosis in cattle. This study investigated whether the reticuloruminal absorption of SCFAs and lactate was altered by different strategies of high concentrate feeding. Eight rumen-cannulated, non-lactating Holstein cows were fed a forage-only diet (baseline and then gradually adapted over 6 d to a 60% concentrate level. Thereafter, this concentrate-rich diet was fed for 4 wk either continuously (Con; n = 8 or interruptedly (Int; n = 8. Absorption of SCFAs and lactate was determined in vivo from the experimental buffer introduced into the washed reticulorumen. The buffer contained acetate, propionate, butyrate and lactate at a concentration of 60, 30, 10 and 5 mmol/L, respectively and Cr-EDTA as a marker for correcting ruminal water fluxes. The reticuloruminal absorption after 35 and 65 min of buffer incubation was measured at the baseline, after 1 wk of 60% concentrate feeding in the interrupted model (Int-1 and after 4 wk of concentrate feeding in both feeding models (Int-4 and Con-4. Data showed that the absorption rates of individual and total SCFAs during the first 35 min of incubation of Con-4 were highest (~1.7 times compared to baseline, while Int-1 and Int-4 were similar to respective baseline. Lactate was not absorbed during forage-only baseline and 1-wk concentrate feeding, but after 4-wk feeding of concentrates in both models. In conclusion, SCFAs absorption across the reticulorumen of non-lactating cattle was enhanced by the 4-wk continuous concentrate feeding, which seems to be more advantageous in terms of rumen acidosis prevention compared to the interrupted feeding model. The study provides

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

Science.gov (United States)

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 ...

Slow-light enhanced absorption in a hollow-core fiber

DEFF Research Database (Denmark)

Grgic, Jure; Xiao, Sanshui; Mørk, Jesper

2010-01-01

Light traversing a hollow-core photonic band-gap fiber may experience multiple reflections and thereby a slow-down and enhanced optical path length. This offers a technologically interesting way of increasing the optical absorption of an otherwise weakly absorbing material which can infiltrate...

Solar absorption surface panel

Science.gov (United States)

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.

Absorption of controlled-release iron

International Nuclear Information System (INIS)

Cook, J.D.; Lipschitz, D.A.; Skikne, B.S.

1982-01-01

A multiple-dose double radioiron technic was used to compare absorption of iron administered as a controlled release (CR) capsule and as an elixir; both formulations contained 50 mg elemental iron as ferrous sulfate. When taken by normal subjects in the fasting state, mean absorption from the elixir and CR capsule averaged 4.92% and 4.38%, which gave a CR capsule:elixir ratio of 0.89. This difference was not significant, but when taken with meals that inhibit absorption of dietary iron by different degrees, absorption of the CR formulation was superior. CR capsule:elixir absorption ratios averaged 1.70 from a meal that is mildly inhibitory and 3.13 from a meal that causes more marked inhibition. It is concluded that CR iron formulations may offer a therapeutic advantage to patients who take oral iron with meals to avoid gastrointestinal side effects

Polarization control of multi-photon absorption under intermediate femtosecond laser field

International Nuclear Information System (INIS)

Cheng Wenjing; Liang Guo; Wu Ping; Liu Pei; Jia Tianqing; Sun Zhenrong; Zhang Shian

2017-01-01

It has been shown that the femtosecond laser polarization modulation is a very simple and well-established method to control the multi-photon absorption process by the light–matter interaction. Previous studies mainly focused on the multi-photon absorption control in the weak field. In this paper, we further explore the polarization control behavior of multi-photon absorption process in the intermediate femtosecond laser field. In the weak femtosecond laser field, the second-order perturbation theory can well describe the non-resonant two-photon absorption process. However, the higher order nonlinear effect (e.g., four-photon absorption) can occur in the intermediate femtosecond laser field, and thus it is necessary to establish new theoretical model to describe the multi-photon absorption process, which includes the two-photon and four-photon transitions. Here, we construct a fourth-order perturbation theory to study the polarization control behavior of this multi-photon absorption under the intermediate femtosecond laser field excitation, and our theoretical results show that the two-photon and four-photon excitation pathways can induce a coherent interference, while the coherent interference is constructive or destructive that depends on the femtosecond laser center frequency. Moreover, the two-photon and four-photon transitions have the different polarization control efficiency, and the four-photon absorption can obtain the higher polarization control efficiency. Thus, the polarization control efficiency of the whole excitation process can be increased or decreased by properly designing the femtosecond laser field intensity and laser center frequency. These studies can provide a clear physical picture for understanding and controlling the multi-photon absorption process in the intermediate femtosecond laser field, and also can provide a theoretical guidance for the future experimental realization. (paper)

Bond length variation in Zn substituted NiO studied from extended X-ray absorption fine structure

Science.gov (United States)

Singh, S. D.; Poswal, A. K.; Kamal, C.; Rajput, Parasmani; Chakrabarti, Aparna; Jha, S. N.; Ganguli, Tapas

2017-06-01

Bond length behavior for Zn substituted NiO is determined through extended x-ray absorption fine structure (EXAFS) measurements performed at ambient conditions. We report bond length value of 2.11±0.01 Å for Zn-O of rock salt (RS) symmetry, when Zn is doped in RS NiO. Bond length for Zn substituted NiO RS ternary solid solutions shows relaxed behavior for Zn-O bond, while it shows un-relaxed behavior for Ni-O bond. These observations are further supported by first-principles calculations. It is also inferred that Zn sublattice remains nearly unchanged with increase in lattice parameter. On the other hand, Ni sublattice dilates for Zn compositions up to 20% to accommodate increase in the lattice parameter. However, for Zn compositions more than 20%, it does not further dilate. It has been attributed to the large disorder that is incorporated in the system at and beyond 20% of Zn incorporation in the cubic RS lattice of ternary solid solutions. For these large percentages of Zn incorporation, the Ni and the Zn atoms re-arrange themselves microscopically about the same nominal bond length rather than systematically increase in magnitude to minimize the energy of the system. This results in an increase in the Debye-Waller factor with increase in the Zn concentration rather than a systematic increase in the bond lengths.

General considerations regarding intestinal absorption of radionuclides as a function of age

International Nuclear Information System (INIS)

Metivier, H.; Fritsch, P.; Lataillade, G.

1987-01-01

Although enhanced absorption of radionuclides from the GI tract has been confirmed in recent years in many animal species, the species-dependent variations in GI absorption by neonates make it difficult to extrapolate animal data to humans. Numerous measurements have been made in 1 to 2 day-old animals, but fewer studies have covered the entire neonatal period up to weaning. For plutonium, sufficiently good inter-species agreement was obtained to assume that its absorption by the GI tract remains significantly high until weaning. The same was reported for neptunium absorption by hamsters but a preliminary experiment with baboons seems to refuse this, and the problem of extrapolation to humans from species more closely related to man remains unsolved. The fact that effects of different factors such as the chemical form of radionuclides, the neonatal transfer of immunoglobulins and intestinal wall permeability, has not been definitely proved also makes such extrapolation difficult. Because the baboon resembles man more than other animals as regards lifespan, length of gestation, the birth of only one animal at a time, the weaning time, the length of adolescence and the time of sexual maturation, it seems to be the animal species most likely to provide suitable data for extrapolation to human. 21 refs.; 3 figs.; 3 tabs

Evaluation of energy absorption performance of steel square profiles with circular discontinuities

Directory of Open Access Journals (Sweden)

Dariusz Szwedowicz

Full Text Available This article details the experimental and numerical results on the energy absorption performance of square tubular profile with circular discontinuities drilled at lengthwise in the structure. A straight profile pattern was utilized to compare the absorption of energy between the ones with discontinuities under quasi-static loads. The collapse mode and energy absorption conditions were modified by circular holes. The holes were drilled symmetrically in two walls and located in three different positions along of profile length. The results showed a better performance on energy absorption for the circular discontinuities located in middle height. With respect to a profile without holes, a maximum increase of 7% in energy absorption capacity was obtained experimentally. Also, the numerical simulation confirmed that the implementation of circular discontinuities can reduce the peak load (Pmax by 10%. A present analysis has been conducted to compare numerical results obtained by means of the finite element method with the experimental data captured by using the testing machine. Finally the discrete model of the tube with and without geometrical discontinuities presents very good agreements with the experimental results.

Nonlinear effects in collective absorption

International Nuclear Information System (INIS)

Uenoyama, Takeshi; Mima, Kunioki; Watanabe, Tsuguhiro.

1981-01-01

The collective absorption of high intensity laser radiation is analyzed numerically. Density profile modification due to the ponderomotive force associating laser radiation and the excited electron plasma waves is self-consistently taken into account, and the intensity dependences of the absorption efficiency are obtained. In the high intensity regime, the absorption efficiency is found to be strongly enhanced in the plasma without flow, but reduced with supersonic flow. (author)

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

Science.gov (United States)

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

2002-01-01

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

Numerical examinations of simplified spondylodesis models concerning energy absorption in magnetic resonance imaging

Directory of Open Access Journals (Sweden)

Hadert Nicole

2016-09-01

Full Text Available Metallic implants in magnetic resonance imaging (MRI are a potential safety risk since the energy absorption may increase temperature of the surrounding tissue. The temperature rise is highly dependent on implant size. Numerical examinations can be used to calculate the energy absorption in terms of the specific absorption rate (SAR induced by MRI on orthopaedic implants. This research presents the impact of titanium osteosynthesis spine implants, called spondylodesis, deduced by numerical examinations of energy absorption in simplified spondylodesis models placed in 1.5 T and 3.0 T MRI body coils. The implants are modelled along with a spine model consisting of vertebrae and disci intervertebrales thus extending previous investigations [1], [2]. Increased SAR values are observed at the ends of long implants, while at the center SAR is significantly lower. Sufficiently short implants show increased SAR along the complete length of the implant. A careful data analysis reveals that the particular anatomy, i.e. vertebrae and disci intervertebrales, has a significant effect on SAR. On top of SAR profile due to the implant length, considerable SAR variations at small scale are observed, e.g. SAR values at vertebra are higher than at disc positions.

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

Science.gov (United States)

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

2016-05-21

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.

Ultrasonic absorption in solid specimens

International Nuclear Information System (INIS)

Siwabessy, P.J. W.; Stewart, G.A.

1996-01-01

As part of a project to measure the absorption of high frequency (50 - 500 kHz) sonar signals in warm sea-water, a laboratory apparatus has been constructed and tested against room temperature distilled water and various solutions of MgSO 4 (chemical relaxation of MgSO 4 is the major contribution to absorption below 200 kHz). The technique involves monitoring the decay of an acoustic signal for different sizes of vessels of water suspended in an evacuated chamber. So far, all containing vessels used have been spherical in shape. Extrapolation of the results to infinite volume yields the absorption due to the water alone. In order to accommodate variations in temperature and pressure, and to make the system more robust (e.g. for ship deck usage), it is desirable to employ stainless steel vessels. However, it was found that the quality of the data was greatly improved when pyrex glass spheres were used. The stainless steel spheres were manufactured by welding together mechanically spun hemispheres. The linear frequency dependence characteristic of acoustic absorption in solids was observed (in contrast to the quadratic frequency dependence of acoustic absorption in water), and the acoustic absorption was found to depend strongly on the thermal history of the steel

Characteristics of water absorption of beans

OpenAIRE

上中, 登紀子; 森, 孝夫; 豊沢, 功; Tokiko, Uenaka; Takao, Mori; Isao, Toyosawa

2001-01-01

Characteristics of water absorption of soybean, azuki bean and kidney beans (cv. Toramame and Taishokintoki) were investigated. The way of water absorption of soybean was different from that of other beans, because soybeans absorbed water from whole surface of seed coat immediately after the immersion. Azuki beans absorbed extremely slowly water from only strophiole, and then the water absorption in other tissue was induced by a certain amount of water absorption playing a role of trigger. Th...

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

International Nuclear Information System (INIS)

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

2005-01-01

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

Atomic absorption spectrophotometry in perspective

International Nuclear Information System (INIS)

Soffiantini, V.

1981-01-01

Atomic absorption spectrophotometry is essentially an analytical technique used for quantitative trace metal analysis in a variety of materials. The speed and specificity of the technique is its greatest advantage over other analytical techniques. What atomic absorption spectrophotometry can and cannot do and its advantages and disadvantages are discussed, a summary of operating instructions are given, as well as a summary of analytical interferences. The applications of atomic absorption spectrophotometry are also shortly discussed

Cryogenic Thermal Absorptance Measurements on Small-Diameter Stainless Steel Tubing

Science.gov (United States)

Tuttle, James; Jahromi, Amir; Canavan, Edgar; DiPirro, Michael

2015-01-01

The Mid Infrared Instrument (MIRI) on the James Webb Space Telescope includes a mechanical cryocooler which cools its detectors to their 6 Kelvin operating temperature. The coolant gas flows through several meters of small-diameter stainless steel tubing, which is exposed to thermal radiation from its environment. Over much of its length this tubing is gold-plated to minimize the absorption of this radiant heat. In order to confirm that the cryocooler will meet MIRI's requirements, the thermal absorptance of this tubing was measured as a function of its environment temperature. We describe the measurement technique and present the results.

Effect of exciton polaritons of absorption edge of GaTe

International Nuclear Information System (INIS)

Kurbatov, L.N.; Dirochka, A.I.; Sosin, V.A.

1979-01-01

The experimental results, pointing to the dependence of spectral and integral coefficients of exciton absorption as well as to the exciton relaxation parameter γsub(0) over the exciton zone on the sample thickness, are presented. It is tried to explain the inverse dependences of absorption intensity in the maximum of αsub(max) and γsub(0) exciton line within the limits of polariton theory. The values of polariton free path length in GaTe at various temperatures, as well as the volume γsub(vol.) and surface γsub(surf.) parameters of exciton relaxation over the exciton zone are discussed

Revisiting Absorptive Capacity

DEFF Research Database (Denmark)

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

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

Compact Integrated DBR Laser Source for Absorption Lidar Instruments, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — We propose to demonstrate a compact integrated laser module that addresses the requirements of the laser source in a water vapor differential absorption lidar (DIAL)...

Heated electron distributions from resonant absorption

International Nuclear Information System (INIS)

DeGroot, J.S.; Tull, J.E.

1975-01-01

A simplified model of resonant absorption of obliquely incident laser light has been developed. Using a 1.5 dimensional electrostatic simulation computer code, it is shown that the inclusion of ion motion is critically important in determining the heated electron distributions from resonant absorption. The electromagnetic wave drives up an electron plasma wave. For long density scale lengths (Lapprox. =10 3 lambda/subD//sube/), the phase velocity of this wave is very large (ω/kapproximately-greater-than10V/sub th/) so that if heating does occur, a suprathermal tail of very energetic electrons is produced. However, the pressure due to this wave steepens the density profile until the density gradient scale length near the critical density (where the local plasma frequency equals the laser frequency) is of order 20lambda/subD//sube/. The electrostatic wave is thus forced to have a much lower phase velocity (ω/kapprox. =2.5V/sub th/). In this case, more electrons are heated to much lower velocities. The heated electron distributions are exponential in velocity space. Using a simple theory it is shown that this property of profile steepening applies to most of a typical laser fusion pulse. This steepening raises the threshold for parametric instabilities near the critical surface. Thus, the extensive suprathermal electron distributions typically produced by these parametric instabilities can be drastically reduced

Absorption and Metabolism of Xanthophylls

Directory of Open Access Journals (Sweden)

Eiichi Kotake-Nara

2011-06-01

Full Text Available 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.

Absorption and metabolism of xanthophylls.

Science.gov (United States)

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.

Ingestion of Casein in a Milk Matrix Modulates Dietary Protein Digestion and Absorption Kinetics but Does Not Modulate Postprandial Muscle Protein Synthesis in Older Men.

Science.gov (United States)

Churchward-Venne, Tyler A; Snijders, Tim; Linkens, Armand M A; Hamer, Henrike M; van Kranenburg, Janneau; van Loon, Luc J C

2015-07-01

The slow digestion and amino acid absorption kinetics of isolated micellar casein have been held responsible for its relatively lower postprandial muscle protein synthetic response compared with rapidly digested proteins such as isolated whey. However, casein is normally consumed within a milk matrix. We hypothesized that protein digestion and absorption kinetics and the subsequent muscle protein synthetic response after micellar casein ingestion are modulated by the milk matrix. The aim of this study was to determine the impact of a milk matrix on casein protein digestion and absorption kinetics and postprandial muscle protein synthesis in older men. In a parallel-group design, 32 healthy older men (aged 71 ± 1 y) received a primed continuous infusion of L-[ring-(2)H5]-phenylalanine, L-[ring-3,5-(2)H2]-tyrosine, and L-[1-(13)C]-leucine, and ingested 25 g intrinsically L-[1-(13)C]-phenylalanine and L-[1-(13)C]-leucine labeled casein dissolved in bovine milk serum (Cas+Serum) or water (Cas). Plasma samples and muscle biopsies were collected in the postabsorptive state and for 300 min in the postprandial period to examine whole-body and skeletal muscle protein metabolism. Casein ingestion increased plasma leucine and phenylalanine concentrations and L-[1-(13)C]-phenylalanine enrichments, with a more rapid rise after Cas vs. Cas+Serum. Nonetheless, dietary protein-derived phenylalanine availability did not differ between Cas+Serum (47 ± 2%, mean ± SEM) and Cas (46 ± 3%) when assessed over the 300-min postprandial period (P = 0.80). The milk matrix did not modulate postprandial myofibrillar protein synthesis rates from 0 to 120 min (0.038 ± 0.005 vs. 0.031 ± 0.007%/h) or from 120 to 300 min (0.052 ± 0.004 vs. 0.067 ± 0.005%/h) after Cas+Serum vs. Cas. Similarly, no treatment differences in muscle protein-bound L-[1-(13)C]-phenylalanine enrichments were observed at 120 min (0.003 ± 0.001 vs. 0.002 ± 0.001) or 300 min (0.015 ± 0.002 vs. 0.016 ± 0.002 mole

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

Directory of Open Access Journals (Sweden)

Akiko Tanaka

Full Text Available 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.

Absorption lines, Faraday rotation, and magnetic field estimates for QSO absorption-line clouds

International Nuclear Information System (INIS)

Kronberg, P.P.; Perry, J.J.

1982-01-01

We have estimated the extragalactic component of Faraday rotation for a sample of 37 QSOs for which there is good absorption line data, which we have also analyzed. Statistical evidence is presented which suggests that we have isolated a component of Faraday rotation which is occurring in the absorption clouds of some QSOs

Study on the prediction of visible absorption maxima of azobenzene compounds

Science.gov (United States)

Liu, Jun-na; Chen, Zhi-rong; Yuan, Shen-feng

2005-01-01

The geometries of azobenzene compounds are optimized with B3LYP/6-311G* method, and analyzed with nature bond orbital, then their visible absorption maxima are calculated with TD-DFT method and ZINDO/S method respectively. The results agree well with the observed values. It was found that for the calculation of visible absorption using ZINDO/S method could rapidly yield better results by adjusting OWFπ-π (the relationship between π-π overlap weighting factor) value than by the TD-DFT method. The method of regression showing the linear relationship between OWFπ-π and BLN-N (nitrogen-nitrogen bond lengths) as OWF π-π=−8.1537+6.5638BL N-N, can be explained in terms of quantum theory, and also be used for prediction of visible absorption maxima of other azobenzne dyes in the same series. This study on molecules’ orbital geometry indicates that their visible absorption maxima correspond to the electron transition from HOMO (the highest occupied molecular orbital) to LUMO (the lowest unoccupied molecular orbital). PMID:15909349

Spectral interferences in atomic absorption spectrometry, (5)

International Nuclear Information System (INIS)

Daidoji, Hidehiro

1979-01-01

Spectral interferences were observed in trace element analysis of concentrated solutions by atomic absorption spectrometry. Molecular absorption and emission spectra for strontium chloride and nitrate, barium chloride and nitrate containing 12 mg/ml of metal ion in airacetylene flame were measured in the wavelength range from 200 to 700 nm. The absorption and emission spectra of SrO were centered near 364.6 nm. The absorption spectra of SrOH around 606.0, 671.0 and 682.0 nm were very strong. And, emission spectrum of BaOH in the wavelength range from 480 to 550 nm was stronger. But, the absorption of this band spectrum was very weak. In the wavelength range from 200 to 400 nm, some unknown bands of absorption were observed for strontium and barium. Absorption spectra of SrCl and BaCl were observed in the argon-hydrogen flame. Also, in the carbon tube atomizer, the absorption spectra of SrCl and BaCl were detected clearly in the wavelength range from 185 to 400 nm. (author)

X-ray absorption in atomic potassium

International Nuclear Information System (INIS)

Gomilsek, Jana Padeznik; Kodre, Alojz; Arcon, Iztok; Nemanic, Vincenc

2008-01-01

A new high-temperature absorption cell for potassium vapor is described. X-ray absorption coefficient of atomic potassium is determined in the energy interval of 600 eV above the K edge where thresholds for simultaneous excitations of 1s and outer electrons, down to [1s2p] excitation, appear. The result represents also the atomic absorption background for XAFS (X-ray absorption fine structure) structure analysis. The K ionization energy in the potassium vapor is determined and compared with theoretical data and with the value for the metal

Scattering and absorption of electromagnetic waves by a Schwarzschild black hole

International Nuclear Information System (INIS)

Fabbri, R.

1975-01-01

The scattering and absorption of electromagnetic waves by a spherically symmetric nonrotating black hole is studied in the Schwarzschild background, by means of the known expansion of the modified Debye potentials in partial waves. The power reflection coefficients and the phase shifts of the partial waves are evaluated at both high and low frequencies. Then the scattering and absorption cross sections of the black hole are determined. It is shown that the black hole is almost unable to absorb electromagnetic waves when the wave length of the radiation is greater than the Schwarzschild radius

Investigating the sensitivity of PMMA optical fibres for use as an evanescent field absorption sensor in aqueous solutions

International Nuclear Information System (INIS)

Lye, P G; Boerkamp, M; Ernest, A; Lamb, D W

2005-01-01

Polymethylmethacrylate (PMMA) optical fibres are low-cost polymer fibres that are generally more physically robust than silica fibres, are more flexible, yet like silica fibres have the potential to be used for practical evanescent field absorption sensors in aqueous solutions. However, evanescent field absorption in aqueous solutions is influenced by more than just the specific absorptivity of the solution in question. The physical configuration of the optical fibre itself, as well as surface charge interactions between the fibre and the chromophore in the solution also significantly affects the sensitivity of the fibre to evanescent field absorption. This paper reports on an investigation of numerous physical phenomena that influence evanescent field absorption for PMMA fibres using an aqueous solution of the dye Amidoblack. Parameters investigated included fibre coiling configuration and bend radius, fibre interaction length, and effect of solution pH. Coiled fibres were found to be more sensitive to evanescent field absorption than straight (uncoiled) lengths, and sensitivity was found to increase with a further reduction in bend radius. At high solution pH, the absorption versus solution concentration proved to be linear whereas at low pH the absorption versus concentration relationship exhibited a clear deviation from linearity. The observed nonlinearity at low pH points to the importance of accounting for electrostatic interactions between chromophore and fibre surface when designing a PMMA sensor for evanescent field absorption measurements in aqueous solutions

Gastrointestinal absorption of Np in rats

International Nuclear Information System (INIS)

Wirth, R.; Volf, V.

1985-01-01

The effect of Np mass and the acidity of the administered Np solutions as well as the age, sex and nutritional status of the animals injected or gavaged with 239Np or 237Np were determined. The latter factor proved to be dominant for absorption of Np from the gut. Thus in fasting weanling and young adult male rats, the absorption of 239Np was sixfold higher (0.18% and 0.12%, respectively) than in fed ones (0.03% and 0.02%, respectively). Absorption by fasted adult females was 0.05% of the administered 239Np, about half of that of adult males. Raising the Np-mass gavaged to fasted female rats to 1 and 10 mg 237Np/kg resulted in an absorption of 0.23% and 0.26%, respectively. Thus, an increased absorption of Np in adult rats seems to be expected only if a large mass is ingested. No dependence of the absorption of Np on nitric acid concentration was found. The data obtained after oral administration of 238Pu and 239Np to adult rats suggest that the f1 factor recommended by the ICRP for fractional absorption of soluble Np compounds from the gut should be decreased, whereas the f1 factor for soluble Pu compounds should be raised

Threshold nonlinear absorption in Zeeman transitions

International Nuclear Information System (INIS)

Narayanan, Andal; Hazra, Abheera; Sandhya, S N

2010-01-01

We experimentally study the absorption spectroscopy from a collection of gaseous 87 Rb atoms at room temperature irradiated with three fields. Two of these fields are in a pump-probe saturation absorption configuration. The third field co-propagates with the pump field. The three fields address Zeeman degenerate transitions between hyperfine levels 5S 1/2 , F = 1 and 5P 3/2 , F = 0, F = 1 around the D2 line. We find a sub-natural absorption resonance in the counter-propagating probe field for equal detunings of all three fields. This absorption arises in conjunction with the appearance of increased transmission due to electro-magnetically induced transparency in the co-propagating fields. The novel feature of this absorption is its onset only for the blue of 5P 3/2 , F = 0, as the laser frequency is scanned through the excited states 5P 3/2 , F = 0, F = 1 and F = 2. The absorption rapidly rises to near maximum values within a narrow band of frequency near 5P 3/2 , F = 0. Our experimental results are compared with a dressed atom model. We find the threshold absorption to be a result of coherent interaction between the dressed states of our system.

Sabine absorption coefficients to random incidence absorption coefficients

DEFF Research Database (Denmark)

Jeong, Cheol-Ho

2014-01-01

into random incidence absorption coefficients for porous absorbers are investigated. Two optimization-based conversion methods are suggested: the surface impedance estimation for locally reacting absorbers and the flow resistivity estimation for extendedly reacting absorbers. The suggested conversion methods...

Agnostic stacking of intergalactic doublet absorption: measuring the Ne VIII population

Science.gov (United States)

Frank, Stephan; Pieri, Matthew M.; Mathur, Smita; Danforth, Charles W.; Shull, J. Michael

2018-05-01

We present a blind search for doublet intergalactic metal absorption with a method dubbed `agnostic stacking'. Using a forward-modelling framework, we combine this with direct detections in the literature to measure the overall metal population. We apply this novel approach to the search for Ne VIII absorption in a set of 26 high-quality COS spectra. We probe to an unprecedented low limit of log N>12.3 at 0.47≤z ≤1.34 over a path-length Δz = 7.36. This method selects apparent absorption without requiring knowledge of its source. Stacking this mixed population dilutes doublet features in composite spectra in a deterministic manner, allowing us to measure the proportion corresponding to Ne VIII absorption. We stack potential Ne VIII absorption in two regimes: absorption too weak to be significant in direct line studies (12.3 13.7). We do not detect Ne VIII absorption in either regime. Combining our measurements with direct detections, we find that the Ne VIII population is reproduced with a power-law column density distribution function with slope β = -1.86 ^{+0.18 }_{ -0.26} and normalization log f_{13.7} = -13.99 ^{+0.20 }_{ -0.23}, leading to an incidence rate of strong Ne VIII absorbers dn/dz =1.38 ^{+0.97 }_{ -0.82}. We infer a cosmic mass density for Ne VIII gas with 12.3 value significantly lower that than predicted by recent simulations. We translate this density into an estimate of the baryon density Ωb ≈ 1.8 × 10-3, constituting 4 per cent of the total baryonic mass.

Glucose absorption in acute peritoneal dialysis.

Science.gov (United States)

Podel, J; Hodelin-Wetzel, R; Saha, D C; Burns, G

2000-04-01

During acute peritoneal dialysis (APD), it is known that glucose found in the dialysate solution contributes to the provision of significant calories. It has been well documented in continuous ambulatory peritoneal dialysis (CAPD) that glucose absorption occurs. In APD, however, it remains unclear how much glucose absorption actually does occur. Therefore, the purpose of this study was to determine whether it is appropriate to use the formula used to calculate glucose absorption in CAPD (Grodstein et al) among patients undergoing APD. Actual measurements of glucose absorption (Method I) were calculated in 9 patients undergoing APD treatment for >24 hours who were admitted to the intensive care unit. Glucose absorption using the Grodstein et al formula (Method II) was also determined and compared with the results of actual measurements. The data was then further analyzed based on the factors that influence glucose absorption, specifically dwell time and concentration. The mean total amount of glucose absorbed was 43% +/- 15%. However, when dwell time and concentration were further examined, significant differences were noted. Method I showed a cumulative increase over time. Method II showed that absorption was fixed. This suggests that with the variation in dwell time commonly seen in the acute care setting, the use of Method II may not be accurate. In each of the 2 methods, a significant difference in glucose absorption was noted when comparing the use of 1.5% and 4.25% dialysate concentrations. The established formula designed for CAPD should not be used for calculating glucose absorption in patients receiving APD because variation in dwell time and concentration should be taken into account. Because of the time constraints and staffing required to calculate each exchange individually, combined with the results of the study, we recommend the use of the percentage estimate of 40% to 50%.

Reproducibility of The Random Incidence Absorption Coefficient Converted From the Sabine Absorption Coefficient

DEFF Research Database (Denmark)

Jeong, Cheol-Ho; Chang, Ji-ho

2015-01-01

largely depending on the test room. Several conversion methods for porous absorbers from the Sabine absorption coefficient to the random incidence absorption coefficient were suggested by considering the finite size of a test specimen and non-uniformly incident energy onto the specimen, which turned out...... resistivity optimization outperforms the surface impedance optimization in terms of the reproducibility....

Tunable evolutions of shock absorption and energy partitioning in magnetic granular chains

Science.gov (United States)

Leng, Dingxin; Liu, Guijie; Sun, Lingyu

2018-01-01

In this paper, we investigate the tunable characteristics of shock waves propagating in one-dimensional magnetic granular chains at various chain lengths and magnetic flux densities. According to the Hertz contact theory and Maxwell principle, a discrete element model with coupling elastic and field-induced interaction potentials of adjacent magnetic grains is proposed. We also present hard-sphere approximation analysis to describe the energy partitioning features of magnetic granular chains. The results demonstrate that, for a fixed magnetic field strength, when the chain length is greater than two times of the wave width of the solitary wave, the chain length has little effect on the output energy of the system; for a fixed chain length, the shock absorption and energy partitioning features of magnetic granular chains are remarkably influenced by varying magnetic flux densities. This study implies that the magnetic granular chain is potential to construct adaptive shock absorption components for impulse mitigation.

Aerosol Absorption Measurements in MILAGRO.

Science.gov (United States)

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

2007-12-01

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

Microwave absorption behaviors of tetra-needle-like ZnO whiskers

International Nuclear Information System (INIS)

Zhou Zuowan; Chu Longsheng; Hu Shuchun

2006-01-01

A novel type of microwave absorption coating was prepared using tetra-needle-like zinc oxide whiskers as the main functional agent. The results of the experiments show that the composite coatings containing ZnO whisker appear to have good efficiency of microwave absorption, and the effect is influenced by the aspect ratio (length to diameter, L/D), the content of the T-ZnO whiskers and the resistivity of the whiskers. Microwave-heat transformation of this kind of whisker and its composite was investigated, and the results indicated that the apparent density affected the efficiency of the heat generating. The suitable value of the apparent density is 0.16-0.18 g/cm 3 . The mechanism of microwave absorption and microwave-heat transformation was explained by the semiconductive networks formed by the tetra-needle shape, diffuse reflections results from quasi-antenna, multipoles due to charge concentration and the multi-interfaces in the composites

Optimization of 1.3-μm InGaAsP/InP Electro-Absorption Modulator

International Nuclear Information System (INIS)

Wang Hui-Tao; Zhou Dai-Bing; Zhang Rui-Kang; Lu Dan; Zhao Ling-Juan; Zhu Hong-Liang; Wang Wei; Ji Chen

2015-01-01

We report the simulation and experimental results of 1.3-μm InGaAsP/InP multiple quantum well (MQW) electro-absorption modulators (EAMs). In this work, the quantum confined Stark effect of the EAM is systematically analyzed through the finite element method. An optimized structure of the 1.3-μm InGaAsP/InP QW EAM is proposed for applications in 100 G ethernet. Then 1.3-μm InGaAsP/InP EAMs with f_−_3 _d_B bandwidth of over 20 GHz and extinction ratio over 20 dB at 3 V bias voltage are demonstrated. (paper)

Converting Sabine absorption coefficients to random incidence absorption coefficients

DEFF Research Database (Denmark)

Jeong, Cheol-Ho

2013-01-01

are suggested: An optimization method for the surface impedances for locally reacting absorbers, the flow resistivity for extendedly reacting absorbers, and the flow resistance for fabrics. With four porous type absorbers, the conversion methods are validated. For absorbers backed by a rigid wall, the surface...... coefficients to random incidence absorption coefficients are proposed. The overestimations of the Sabine absorption coefficient are investigated theoretically based on Miki's model for porous absorbers backed by a rigid wall or an air cavity, resulting in conversion factors. Additionally, three optimizations...... impedance optimization produces the best results, while the flow resistivity optimization also yields reasonable results. The flow resistivity and flow resistance optimization for extendedly reacting absorbers are also found to be successful. However, the theoretical conversion factors based on Miki's model...

Field Measurements of Water Continuum and Water Dimer Absorption by Active Long Path Differential Optical Absorption Spectroscopy (DOAS)

OpenAIRE

Lotter, Andreas

2006-01-01

Water vapor plays an important role in Earth's radiative budget since water molecules strongly absorb the incoming solar shortwave and the outgoing thermal infrared radiation. Superimposed on the water monomer absorption, a water continuum absorption has long been recognized, but its true nature still remains controversial. On the one hand, this absorption is explained by a deformation of the line shape of the water monomer absorption lines as a consequence of a molecular collision. One the o...

Regional distribution and variation of gamma-globulin absorption from the small intestine of the neonatal calf

International Nuclear Information System (INIS)

Fetcher, A.; Gay, C.C.; McGuire, T.C.; Barbee, D.D.; Parish, S.M.

1983-01-01

125I-labeled immunoglobulin (Ig)G1 in colostral whey was used to determine the region of maximum absorption of Ig from the small intestine of the neonatal calf and the variation in Ig absorption among calves at the intestinal level. In experiment 1, 5 segments (approx 5%, 35%, 60%, 80%, and 95% of the duodenocecal length) were formed in the small intestine of 9 colostrum-deprived calves shortly after birth. These segments were injected with colostral whey containing 125I-IgG1 4 hours after birth, and uptake, transfer, and absorption (defined as uptake plus transfer) were determined for each segment 2 hours later. Raw data were adjusted for the milligrams of IgG1 injected per gram of intestinal tissue to obtain the least squares mean (LSM) value. The LSM values for absorption of IgG1 from distal segments 3, 4, and 5 were significantly greater (P less than 0.05) than those values for proximal segments 1 and 2. The region of the maximum IgG1 absorption was the lower small intestine, 60% to 80% of the duodenocecal length. There was also an indication of independence between uptake and transfer in each of the segments. Significant differences (P less than 0.05) were present among calves in the LSM values for uptake and absorption, but not for transfer. In experiment 2, thoracic ducts of 8 newborn calves were cannulated 4 to 5 hours after birth. At 6 hours after birth, colostral whey with 125I-IgG1 was injected into an intestinal segment (approx 60% to 80% of the duodenocecal length)

Optical absorption measurement system

International Nuclear Information System (INIS)

Draggoo, V.G.; Morton, R.G.; Sawicki, R.H.; Bissinger, H.D.

1989-01-01

This patent describes 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

Iron, lead, and cobalt absorption: similarities and dissimilarities

International Nuclear Information System (INIS)

Barton, J.C.; Conrad, M.E.; Holland, R.

1981-01-01

Using isolated intestinal segments in rats, the absorption of iron, lead, and cobalt was increased in iron deficiency and decreased in iron loading. Similarly, the absorption of these metals was decreased in transfusional erythocytosis, after intravenous iron injection and after parenteral endotoxin injection. Acute bleeding or abbreviated intervals of dietary iron deprivation resulted in increased iron absorption from isolated intestinal segments and in intact animals, while the absorption of lead and cobalt was unaffected. These results suggest that the specificity of the mucosal metal absorptive mechanism is either selectively enhanced for iron absorption by phlebotomy or brief periods of dietary iron deprivation, or that two or more mucosal pathways for iron absorption may exist

On pair-absorption in intrinsic vapours

International Nuclear Information System (INIS)

Hotop, R.; Niemax, K.; Schlueter, D.

1982-01-01

The bound-state pair-absorption bands Cs(6 2 S 1 sub(/) 2 ) + Cs(6 2 S 1 sub(/) 2 ) + hν → Cs(5 2 D 5 sub(/) 2 sub(,) 3 sub(/) 2 ) + Cs(6 2 P 1 sub(/) 2 ) and the K-K continuum-state pair-absorptions in the wavelength region 2.350 <= lambda <= 2.850 Angstroem have been investigated experimentally. In the case of the bound-state pair-absorption bands a theoretical approach for the absorption cross section at the band centre is given which is in good agreement with the experimental observation. Differences between our and the theoretical formulas given by the Stanford group are discussed. (orig.)

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

Energy Technology Data Exchange (ETDEWEB)

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

1998-12-31

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

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

Energy Technology Data Exchange (ETDEWEB)

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

1997-12-31

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

Iron absorption after antrectomy with gastroduodenostomy

International Nuclear Information System (INIS)

Magnusson, B.E.O.

1976-01-01

Haematological values were studied in 177 unselected patients 3-6 years after antrectomy with gastroduodenostomy. The majority (76%) had been operated upon for duodenal ulcer, 20% for gastric ulcer and the remaining patients had had both a duodenal and a gastric ulcer before the operation. In 65 patients a vagotomy had been added to the resection. 10% of the males and 15% of the females had a haemoglobin concentration below 13.0 or 12.0 g/100 ml, respectively. The corresponding frequencies for iron defifiency, defined as absence or only traces of haemosiderin in bone marrow smears, were 7% and 15%. The absorption of a small test dose of inorganic iron (0.56 mg Fe ++ as ferrous ascorbate) was studied in all the antrectomized patients. The absorption was also investigated in normal men and in patients who had had a Billroth II partial gastrectomy. No malabsorption of inorganic iron could be found in any of the groups. An inverse relationship between iron absorption and the grading of haemosiderin in bone marrow smears was found in normal subjects as well as in operated patients. Thus, an adequate increase of the absorption of ferrous iron was found even in operated patients with iron deficiency. Gastric acid secretion, measured as the peak acid output (PAO) after stimulation, was determined in all antrectomized patients. In patients having the same grading of haemosiderin (grade II) a slight but significant positive correlation was found between PAO and the absorption from the test dose (Fe ++ ). The absorption of food iron from a composite meal and the absorption from an iron salt (3.0 mg Fe ++ as ferrous ascorbate) was studied in 4 different groups: 1) normal males, 2) non-operated patients with peptic ulcer, 3) antrectomized patients with gastroduodenostomy and 4) patients operated upon with Billroth II partial gastrectomy. The range and mean absorption values from the test dose of inorganic iron were about the same in all groups. The absorption of food iron

Lithium absorption by the rabbit gall-bladder

DEFF Research Database (Denmark)

Hansen, C P; Holstein-Rathlou, N H; Skøtt, O

1991-01-01

Lithium (Li+) absorption across the low-resistance epithelium of the rabbit gall-bladder was studied in order to elucidate possible routes and mechanisms of Li+ transfer. Li+ at a concentration of 0.4 mM in both mucosal and serosal media did not affect isosmotic mucosa-to-serosa fluid absorption...... was elicited from the mucosal side and was not accounted for by compensatory Li+ absorption; water and Na+ absorption rates decreased nearly in parallel. The effects of 0.4 mM amiloride and of substitution with 20 mM Li+ were only partly additive. It is concluded that Li+ absorption in the rabbit gall...

Sublinear absorption in OCS gas

International Nuclear Information System (INIS)

Bogani, F.; Querzoli, R.; Ernst, K.

1988-01-01

Sublinear absorption in OCS gas has been experimentally studied in detail by means of an optoacustic technique and transmission measurements. The best fit of the results is obtained by a phenomenological model, that considers the process as the sum of one-and two-photon absorptions

Lactulose stimulates calcium absorption in postmenopausal women

NARCIS (Netherlands)

Heuvel, E.G.H.M. van den; Muijs, T.; Dokkum, W. van; Schaafsma, G.

1999-01-01

Animal studies have indicated that calcium absorption is increased by lactulose, a synthetic disaccharide. Therefore, the influence of lactulose on calcium absorption was measured in postmenopausal women who may benefit from the possible enhancing effect of lactulose on calcium absorption. Twelve

51Cr-ethylenediaminetetraacetic acid absorption test

International Nuclear Information System (INIS)

Aabakken, L.

1989-01-01

The 51 Cr-ethylenediaminetetraacetic acid (EDTA) absorption test was evaluated in 83 healthy, male volunteers. Base-line 24 h excretion after peroral administration ranged from 0.88% to 7.96%, with a higher median absorption than reported by most authors (2.45%). However, the reproducibility and stability of the method and the reproducibility of the results were satisfactory. Urinary excretion after intraduodenal installation (n=18) was comparable to that seen after peroral test dose administration, indicating a limited significance of gastric 51 Cr-EDTA absorption under normal conditions. In 16 subjects a single intake of alcohol immediately before the test gave a modest and short-lasting increase in 51 Cr-EDTA absorption. No correlation was seen to body mass index, creatinine clearance, urinary volume, or small-bowel transit time, possibly reducing the number of confounding factors in the evaluation of absorption data. A small but significant negative correlation was, however, found to body surface area and age

Absorption of scintillation light in a 100l liquid xenon γ-ray detector and expected detector performance

International Nuclear Information System (INIS)

Baldini, A.; Bemporad, C.; Cei, F.; Doke, T.; Grassi, M.; Grebenuk, A.A.; Grigoriev, D.N.; Haruyama, T.; Kasami, K.; Kikuchi, J.; Maki, A.; Mashimo, T.; Mihara, S.; Mitsuhashi, T.; Mori, T.; Nicolo, D.; Nishiguchi, H.; Ootani, W.; Ozone, K.; Papa, A.; Pazzi, R.; Ritt, S.; Sawada, R.; Sergiampietri, F.; Signorelli, G.; Suzuki, S.; Terasawa, K.; Yamashita, M.; Yamashita, S.; Yoshimura, T.; Yuri, Yu.

2005-01-01

An 800l liquid xenon scintillation γ-ray detector is being developed for the MEG experiment which will search for μ + ->e + γdecay at the Paul Scherrer Institut. Absorption of scintillation light of xenon by impurities might possibly limit the performance of such a detector. We used a 100l prototype with an active volume of 372x372x496mm 3 to study the scintillation light absorption. We have developed a method to evaluate the light absorption, separately from elastic scattering of light, by measuring cosmic rays and α sources. By using a suitable purification technique, an absorption length longer than 100cm has been achieved. The effects of the light absorption on the energy resolution are estimated by Monte Carlo simulation

Water absorption characteristic of interlocking compressed earth brick units

Science.gov (United States)

Bakar, B. H. Abu; Saari, S.; Surip, N. A.

2017-10-01

This study aims to investigate the water absorption characteristic of interlocking compressed earth brick (ICEB) units. Apart from compressive strength, water absorption is an important property in masonry. This property can affect the quality of the brick itself and the bond strength between the brick and mortar in masonry structures and can result in reducing its strength properties. The units were tested for 24 h water absorption and 5 h boiling water absorption. A total of 170 ICEB units from four ICEB types underwent both tests. For the 24 h water absorption, the ICEB units were dried in the oven for 24 h and then cooled before being weighed. Thereafter, each brick was immersed in water for 24 h and weighed. The same specimens used for the 24 h water absorption test were re-used for the 5 h boiling water absorption test. After completing the 24 h water absorption test, the brick was boiled for 5-hours and weighed. The highest water absorption for the ICEBs in the 24-hour water absorption and 5 h boiling water absorption tests are 15.09% and 17.18%, respectively. The half brick has the highest water absorption (15.87%), whereas the beam brick has the lowest (13.20%). The water absorption of an ICEB unit is higher than that of normal bricks, although the water absorption of the former remains below the maximum rate of the brick water absorption (21%).

Frequency Modulation and Absorption Improvement of THz Micro-bolometer with Micro-bridge Structure by Spiral-Type Antennas.

Science.gov (United States)

Gou, Jun; Niu, Qingchen; Liang, Kai; Wang, Jun; Jiang, Yadong

2018-03-05

Antenna-coupled micro-bridge structure is proven to be a good solution to extend infrared micro-bolometer technology for THz application. Spiral-type antennas are proposed in 25 μm × 25 μm micro-bridge structure with a single separate linear antenna, two separate linear antennas, or two connected linear antennas on the bridge legs, in addition to traditional spiral-type antenna on the support layer. The effects of structural parameters of each antenna on THz absorption of micro-bridge structure are discussed for optimized absorption of 2.52 THz wave radiated by far infrared CO 2 lasers. The design of spiral-type antenna with two separate linear antennas for wide absorption peak and spiral-type antenna with two connected linear antennas for relatively stable absorption are good candidates for high absorption at low absorption frequency with a rotation angle of 360*n (n = 1.6). Spiral-type antenna with extended legs also provides a highly integrated micro-bridge structure with fast response and a highly compatible, process-simplified way to realize the structure. This research demonstrates the design of several spiral-type antenna-coupled micro-bridge structures and provides preferred schemes for potential device applications in room temperature sensing and real-time imaging.

Absorptive capacity and smart companies

Directory of Open Access Journals (Sweden)

Patricia Moro González

2014-12-01

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

Enriching Absorptive Capacity Through Social Interaction

DEFF Research Database (Denmark)

Hotho, Jasper Jaap; Becker-Ritterspach, Florian; Saka-Helmhout, Ayse

their organization’s capacity to put new knowledge to use. To address this shortcoming we conduct an in-depth comparative case study of a headquarters-initiated knowledge transfer initiative at two subsidiaries of the same MNE. The findings demonstrate that social interaction is a key requirement for subsidiary....... These insights contribute to the absorptive capacity literature by demonstrating the scale and scope of social interaction as the key link between individual- and organizational-level absorptive capacity.......Absorptive capacity is frequently highlighted as a key determinant of knowledge transfer within MNEs. But how individual behaviour translates to absorptive capacity at the subsidiary level, and exactly how this is contingent on subsidiaries’ social context, remains under-addressed. This not only...

Enriching Absorptive Capacity through Social Interaction

DEFF Research Database (Denmark)

Hotho, Jasper J.; Saka-Helmhout, Ayse; Becker-Ritterspach, Florian

2012-01-01

their organization's capacity to put new knowledge to use. To address this shortcoming we conduct an in-depth comparative case study of a headquarters-initiated knowledge transfer at two subsidiaries of the same multinational enterprise. The findings demonstrate that social interaction is a prerequisite...... or constraining local interaction patterns. These insights contribute to the absorptive capacity literature by demonstrating the scale and scope of social interaction as a key link between individual- and organizational-level absorptive capacity.......Absorptive capacity is frequently highlighted as a key determinant of knowledge transfer within multinational enterprises. But how individual behaviour translates into absorptive capacity at the subsidiary level, and how this is contingent on subsidiaries' social context, remains under...

Absorption Spectra of Gold Nanoparticle Suspensions

Science.gov (United States)

Anan'eva, M. V.; Nurmukhametov, D. R.; Zverev, A. S.; Nelyubina, N. V.; Zvekov, A. A.; Russakov, D. M.; Kalenskii, A. V.; Eremenko, A. N.

2018-02-01

Three gold nanoparticle suspensions are obtained, and mean radii in distributions - (6.1 ± 0.2), (11.9 ± 0.3), and (17.3 ± 0.7) nm - are determined by the transmission electron microscopy method. The optical absorption spectra of suspensions are obtained and studied. Calculation of spectral dependences of the absorption index of suspensions at values of the gold complex refractive index taken from the literature showed a significant deviation of experimental and calculated data in the region of 450-800 nm. Spectral dependences of the absorption of suspensions are simulated within the framework of the Mie-Drude theory taking into account the interband absorption in the form of an additional term in the imaginary part of the dielectric permittivity of the Gaussian type. It is shown that to quantify the spectral dependences in the region of the plasmon absorption band of nanoparticles, correction of the parameters of the interband absorption is necessary in addition to the increase of the relaxation parameter of the Drude theory. Spectral dependences of the dielectric permittivity of gold in nanodimensional state are refined from the solution of the inverse problem. The results of the present work are important for predicting the special features of operation of photonic devices and optical detonators based on gold nanoparticles.

Wave energy absorption by ducks

OpenAIRE

Kurniawan, Adi

2017-01-01

We study the absorption of wave energy by a single and multiple cam-shaped bodies referred to as ducks. Numerical models are developed under the assumptions of linear theory. We consider wave absorption by a single duck as well as by two lines of ducks meeting at an angle.

Wave energy absorption by ducks

DEFF Research Database (Denmark)

Kurniawan, Adi

2018-01-01

We study the absorption of wave energy by a single and multiple cam-shaped bodies referred to as ducks. Numerical models are developed under the assumptions of linear theory. We consider wave absorption by a single duck as well as by two lines of ducks meeting at an angle....

Water absorption in brick masonry

NARCIS (Netherlands)

Brocken, H.J.P.; Smolders, H.R.

1996-01-01

The water absorption in brick, mortar that was cured separately, and masonry samples was studied using NMR. Models of the moisture transport are usually formulated on the basis of a diffusion equation. In the case of water absorption in separate brick and mortar samples, the moisture diffusivity in

The effect of volatility on percutaneous absorption.

Science.gov (United States)

Rouse, Nicole C; Maibach, Howard I

2016-01-01

Topically applied chemicals may volatilize, or evaporate, from skin leaving behind a chemical residue with new percutaneous absorptive capabilities. Understanding volatilization of topical medications, such as sunscreens, fragrances, insect repellants, cosmetics and other commonly applied topicals may have implications for their safety and efficacy. A systematic review of English language articles from 1979 to 2014 was performed using key search terms. Articles were evaluated to assess the relationship between volatility and percutaneous absorption. A total of 12 articles were selected and reviewed. Key findings were that absorption is enhanced when coupled with a volatile substance, occlusion prevents evaporation and increases absorption, high ventilation increases volatilization and reduces absorption, and pH of skin has an affect on a chemical's volatility. The articles also brought to light that different methods may have an affect on volatility: different body regions; in vivo vs. in vitro; human vs. Data suggest that volatility is crucial for determining safety and efficacy of cutaneous exposures and therapies. Few articles have been documented reporting evaporation in the context of percutaneous absorption, and of those published, great variability exists in methods. Further investigation of volatility is needed to properly evaluate its role in percutaneous absorption.

Aerosol Angstrom Absorption Coefficient Comparisons during MILAGRO.

Science.gov (United States)

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 (Petroleo (IMP) and CENICA.

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

Energy Technology Data Exchange (ETDEWEB)

Sun, Luming; Zhou, Hongyan; Ji, Tuo; Jiang, Peng; Liu, Bo; Pan, Xiang; Shi, Xiheng; Zhang, Shaohua [Polar Research Institute of China, 451 Jinqiao Road, Shanghai (China); Liu, Wenjuan; Wang, Jianguo [Yunnan Observatories, Chinese Academy of Sciences, Kunming, Yunnan (China); Wang, Tinggui; Yang, Chenwei [Department of Astronomy, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui (China); Miller, Lauren P., E-mail: lmsun@mail.ustc.edu.cn [Lehigh University, 27 Memorial Drive West, Bethlehem, PA 18015 (United States)

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{sup −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{sup −1} has a density in the range of 10{sup 9} to 10{sup 10} cm{sup −3} and a distance of ∼1 pc, and the gas with blueshift velocity of ∼1400 km s{sup −1} has a density of 10{sup 3} cm{sup −3} and a distance of ∼1 kpc.

Uniform semiclassical approximation for absorptive scattering systems

International Nuclear Information System (INIS)

Hussein, M.S.; Pato, M.P.

1987-07-01

The uniform semiclassical approximation of the elastic scattering amplitude is generalized to absorptive systems. An integral equation is derived which connects the absorption modified amplitude to the absorption free one. Division of the amplitude into a diffractive and refractive components is then made possible. (Author) [pt

Absorption factor for cylindrical samples

International Nuclear Information System (INIS)

Sears, V.F.

1984-01-01

The absorption factor for the scattering of X-rays or neutrons in cylindrical samples is calculated by numerical integration for the case in which the absorption coefficients of the incident and scattered beams are not equal. An extensive table of values having an absolute accuracy of 10 -4 is given in a companion report [Sears (1983). Atomic Energy of Canada Limited, Report No. AECL-8176]. In the present paper an asymptotic expression is derived for the absorption factor which can be used with an error of less than 10 -3 for most cases of interest in both neutron inelastic scattering and neutron diffraction in crystals. (Auth.)

LASER PLASMA AND LASER APPLICATIONS: Plasma transparency in laser absorption waves in metal capillaries

Science.gov (United States)

Anisimov, V. N.; Kozolupenko, A. P.; Sebrant, A. Yu

1988-12-01

An experimental investigation was made of the plasma transparency to heating radiation in capillaries when absorption waves propagated in these capillaries as a result of interaction with a CO2 laser pulse of 5-μs duration. When the length of the capillary was in excess of 20 mm, total absorption of the radiation by the plasma was observed at air pressures of 1-100 kPa. When the capillary length was 12 mm, a partial recovery of the transparency took place. A comparison was made with the dynamics and recovery of the plasma transparency when breakdown of air took place near the free surface.

Importance of the green color, absorption gradient, and spectral absorption of chloroplasts for the radiative energy balance of leaves.

Science.gov (United States)

Kume, Atsushi

2017-05-01

Terrestrial green plants absorb photosynthetically active radiation (PAR; 400-700 nm) but do not absorb photons evenly across the PAR waveband. The spectral absorbance of photosystems and chloroplasts is lowest for green light, which occurs within the highest irradiance waveband of direct solar radiation. We demonstrate a close relationship between this phenomenon and the safe and efficient utilization of direct solar radiation in simple biophysiological models. The effects of spectral absorptance on the photon and irradiance absorption processes are evaluated using the spectra of direct and diffuse solar radiation. The radiation absorption of a leaf arises as a consequence of the absorption of chloroplasts. The photon absorption of chloroplasts is strongly dependent on the distribution of pigment concentrations and their absorbance spectra. While chloroplast movements in response to light are important mechanisms controlling PAR absorption, they are not effective for green light because chloroplasts have the lowest spectral absorptance in the waveband. With the development of palisade tissue, the incident photons per total palisade cell surface area and the absorbed photons per chloroplast decrease. The spectral absorbance of carotenoids is effective in eliminating shortwave PAR (solar radiation. However, most of the near infrared radiation is unabsorbed and heat stress is greatly reduced. The incident solar radiation is too strong to be utilized for photosynthesis under the current CO 2 concentration in the terrestrial environment. Therefore, the photon absorption of a whole leaf is efficiently regulated by photosynthetic pigments with low spectral absorptance in the highest irradiance waveband and through a combination of pigment density distribution and leaf anatomical structures.

Broadening the absorption bandwidth of metamaterial absorbers by transverse magnetic harmonics of 210 mode.

Science.gov (United States)

Long, Chang; Yin, Sheng; Wang, Wei; Li, Wei; Zhu, Jianfei; Guan, Jianguo

2016-02-18

By investigating a square-shaped metamaterial structure we discover that wave diffraction at diagonal corners of such a structure excites transverse magnetic harmonics of 210 mode (TM210 harmonics). Multi-layer overlapping and deliberately regulating period length between adjacent unit cells can significantly enhance TM210 harmonics, leading to a strong absorption waveband. On such a basis, a design strategy is proposed to achieve broadband, thin-thickness multi-layered metamaterial absorbers (MMAs). In this strategy big pyramidal arrays placed in the "white blanks" of a chessboard exhibit two isolated absorption bands due to their fundamental and TM210 harmonics, which are further connected by another absorption band from small pyramidal arrays in the "black blanks" of the chessboard. The as-designed MMA at a total thickness (h) of 4.36 mm shows an absorption of above 0.9 in the whole frequency range of 7-18 GHz, which is 38% broader with respect to previous design methods at the same h. This strategy provides an effective route to extend the absorption bandwidth of MMAs without increasing h.

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

Science.gov (United States)

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. Copyright © 2015 Elsevier Inc. All rights reserved.

Comment on resonant absorption

International Nuclear Information System (INIS)

Hammerling, P.

1977-01-01

An average over angles of incidence of the usual resonant absorption function is presented. This form is appropriate under experimental conditions where the angles of incidence vary greatly and in an unknown manner. For comparison a lens-ellipsoidal mirror illumination system with a known longitudinal aberration is considered. In the latter example the angles of incidence are readily obtained and the resulting resonance absorption function evaluated. The associated fields are calculated in a similar fashion. (author)

High-efficient light absorption of monolayer graphene via cylindrical dielectric arrays and the sensing application

Science.gov (United States)

Zhou, Peng; Zheng, Gaige

2018-04-01

The efficiency of graphene-based optoelectronic devices is typically limited by the poor absolute absorption of light. A hybrid structure of monolayer graphene with cylindrical titanium dioxide (TiO2) array and aluminum oxide (Al2O3) spacer layer on aluminum (Al) substrate has been proposed to enhance the absorption for two-dimensional (2D) materials. By combining dielectric array with metal substrate, the structure achieves multiple absorption peaks with near unity absorbance at near-infrared wavelengths due to the resonant effect of dielectric array. Completed monolayer graphene is utilized in the design without any demand of manufacture process to form the periodic patterns. Further analysis indicates that the near-field enhancement induced by surface modes gives rise to the high absorption. This favorable field enhancement and tunability of absorption not only open up new approaches to accelerate the light-graphene interaction, but also show great potential for practical applications in high-performance optoelectronic devices, such as modulators and sensors.

Comparative analysis of CO2 separation from flue gas by membrane gas absorption technology and chemical absorption technology in China

International Nuclear Information System (INIS)

Yan, Shuiping; Fang, Mengxiang; Zhang, Weifeng; Zhong, Weilong; Luo, Zhongyang; Cen, Kefa

2008-01-01

This paper firstly evaluated the CO 2 absorption performance of a membrane gas absorption system (MAS) and chemical absorption system (CAS) using the overall mass transfer coefficient (K G a V ) as a basis for comparison. MAS selected microporous polypropylene (PP) hollow fiber membrane contactors to capture CO 2 from the simulated flue gas while CAS used a randomly packed column containing stainless Pall packing. Aqueous monoethanolamine (MEA) solution was adopted in both absorbers. Experimental results show that if the fresh membranes were tested, MAS has the higher K G a V values than that of CAS. However, when all the membrane pores were completely wetted or 50% pores were plugged, CAS inversely performs better than MAS in terms of K G a V values. In addition, the economic performance of MAS and CAS was also estimated. Results indicate that if the real operational time of membrane module is reduced to less than the critical value affected by the membrane price, the CO 2 captured cost of MAS is inversely higher than that of CAS. Therefore, the current well-accepted statement that MAS is superior to CAS in any case may be somewhat arbitrary unless membrane pore-wetting and pore-plugging problems, how to reduce the membrane price and how to prolong the membrane lifetime can be solved perfectly in the future. (author)

Atomic absorption instrument functional description

International Nuclear Information System (INIS)

Bystroff, R.I.; Boyle, W.G. Jr.; Barton, G.W. Jr.

1976-01-01

This report describes a proposed system for automating atomic absorption analysis. The system consists of two atomic absorption instruments and an automatic sampler that can be attached to either instrument. A computer program controls the sampling and gathers data. The program then uses the data to perform bookkeeping, data processing, and report writing

Understanding Absorptive Capacities is an "Innovation Systems" Context

DEFF Research Database (Denmark)

Narula, Rajneesh

2004-01-01

This paper seeks to broaden our understanding of the concept underlying absorptive capacity atthe macro -level, paying particular attention to the growth and development perspectives. Weprovide definitions of absorptive and technological capacity, external technology flows,productivity growth....... We also undertake to explain how the nature ofabsorptive capacity changes with stages of economic development, and the importance of thedifferent aspects of absorptive capability at different stages. The relationship is not a linear one:the benefits that accrue from marginal increases in absorptive...... capability change over time.Finally, we provide a tentative and preliminary conceptual argument of how the different stagesof absorptive capacity are related to productivity growth, economic growth and employmentcreation.Key words: New economy, absorptive capacity, knowledge...

The day to night absorption ratio in auroral and subauroral zone riometer measurements during auroral absorption

International Nuclear Information System (INIS)

Ranta, H.; Ranta, A.; Rosenberg, T.J.

1984-01-01

The day to night ratio of auroral absorption has been studied using data from auroral and subauroral latitudes and by application of different kinds of statistical analyses. Ratios between 0.5 and 3.0 are obtained, depending on the criteria applied to the selection of data. Previous studies obtained similar ratios, but reached different conclusions about the effective solar control of auroral absorption. It is concluded here that evidence of solar control of the day to night ratio of auroral absorption, or the lack thereof, cannot be extracted by these statistical analyses. (author)

Biotin absorption by distal rat intestine

International Nuclear Information System (INIS)

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

1987-01-01

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

Iron absorption from adequate Filipinos meals

International Nuclear Information System (INIS)

Trinidad, T.P.; Madriaga, J.R.; Valdez, D.H.; Cruz, E.M.; Mallillin, A.C.; Sison, C.C.; Kuizon, M.D.

1989-01-01

Iron absorption from adequate Filipino meals representing the three major island groups of the Philippines (Luzon, Visayas, and Mindanao) was studied using double isotope extrinsic tag method. Mean iron absorption of the one-day meal for Metro Manila was 6.6 +- 1.26%. Central Visayas, 6.3 +- 1.15% and Southern Mindanao, 6.4 +- 1.19%. Comparison between meals (breakfast, lunch, dinner) for each region as well as one-day meal for the three regions showed no significant differences (P>0.01). Correlation tests done between iron absorption and the following iron enhancers: ascorbic acid, amount of fish, meat or poultry; and inhibitors: phytic acid and tannic acid, did not give significant results. The overall average of 6.4 +- 1.20% may be used as the iron absorption level from an adequate Filipino meal. This value can be considered as one of the bases for arriving at recommended dietary allowances for iron among Filipinos instead of the 10% iron absorption assumed in 1976. (Auth.). 21 refs.; 3 tabs.; 3 annexes

Iron absorption from adequate Filipino meals

International Nuclear Information System (INIS)

Trinidad, T.P.; Madriaga, J.R.; Valdez, D.H.; Cruz, E.M.; Mallillin, A.C.; Sison, C.C.; Kuizon, M.D.

1991-01-01

Iron absorption from adequate Filipino meals representing the three major island groups of the Philippines (Luzon, Visayas and Mindanao) was studied using double isotope extrinsic tag method. Mean iron absorption of the one-day meal for Metro Manila was 6.6 ± 1.26%, Central Visayas, 6.3 ± 1.15% and Southern Mindanao, 6.4 ± 1.19%. Comparison between meals (breakfast, lunch, dinner) for each region as well as one-day meal for the three regions showed no significant differences (P > .01). Correlation tests done between iron absorption and the following iron enhancers: ascorbic acid, amount of fish, meat or poultry and inhibitors: phytic acid and tannic acid did not give significant results. The overall bar x of 6.4 ± 1.20% may be used as the non-heme iron absorption level from an adequate Filipino meal. This value can be considered as one of the bases for arriving at recommended dietary allowances for iron among Filipinos instead of the 10% iron absorption assumed in 1976

Emission and Absorption Entropy Generation in Semiconductors

DEFF Research Database (Denmark)

Reck, Kasper; Varpula, Aapo; Prunnila, Mika

2013-01-01

While emission and absorption entropy generation is well known in black bodies, it has not previously been studied in semiconductors, even though semiconductors are widely used for solar light absorption in modern solar cells [1]. We present an analysis of the entropy generation in semiconductor...... materials due to emission and absorption of electromagnetic radiation. It is shown that the emission and absorption entropy generation reduces the fundamental limit on the efficiency of any semiconductor solar cell even further than the Landsberg limit. The results are derived from purely thermodynamical...

CD36 mediates both cellular uptake of very long chain fatty acids and their intestinal absorption in mice.

Science.gov (United States)

Drover, Victor A; Nguyen, David V; Bastie, Claire C; Darlington, Yolanda F; Abumrad, Nada A; Pessin, Jeffrey E; London, Erwin; Sahoo, Daisy; Phillips, Michael C

2008-05-09

The intestine has an extraordinary capacity for fatty acid (FA) absorption. Numerous candidates for a protein-mediated mechanism of dietary FA absorption have been proposed, but firm evidence for this process has remained elusive. Here we show that the scavenger receptor CD36 is required both for the uptake of very long chain FAs (VLCFAs) in cultured cells and the absorption of dietary VLCFAs in mice. We found that the fraction of CD36-dependent saturated fatty acid association/absorption in these model systems is proportional to the FA chain length and specific for fatty acids and fatty alcohols containing very long saturated acyl chains. Moreover, intestinal VLCFA absorption is completely abolished in CD36-null mice fed a high fat diet, illustrating that the predominant mechanism for VLCFA absorption is CD36-dependent. Together, these findings represent the first direct evidence for protein-facilitated FA absorption in the intestine and identify a novel therapeutic target for the treatment of diseases characterized by elevated VLCFA levels.

Effect of oils on drug absorption

OpenAIRE

Palin, K.J.

1981-01-01

Oil and emulsion vehicles have been shown to alter the oral absorption of many drugs. This may be due to enhanced lymph flow and/or altered gastro-intestinal motility in the presence of the oils. The oral absorption of a model compound (DOT) in the presence of three chemically different oils, arachis oil, Miglyol 812 and liquid paraffin was investigated in rats, the influence of lymphatic absorption and gastro-intestinal motility being determined. The findings were applied to the for.mulation...

Vitamin B12 absorption from eggs.

Science.gov (United States)

Doscherholmen, A; McMahon, J; Ripley, D

1975-09-01

The assimilation of 57Co B12 from in vivo labeled eggs was much inferior to that of a comparable amount of crystalline 57Co B12. Furthermore, the absorption varied with the form in which the eggs were served. Judged by the urinary excretion test and the plasma absorption of radioactivity the average absorption from boiled and fried eggs was more than twice that from scrambled whole eggs, but less than half that absorbed from crystalline 57Co B12.

Iron absorption studies

International Nuclear Information System (INIS)

Ekenved, G.

1976-01-01

The main objective of the present work was to study iron absorption from different iron preparations in different types of subjects and under varying therapeutic conditions. The studies were performed with different radioiron isotope techniques and with a serum iron technique. The preparations used were solutions of ferrous sulphate and rapidly-disintegrating tablets containing ferrous sulphate, ferrous fumarate and ferrous carbonate and a slow-release ferrous sulphate tablet of an insoluble matrix type (Duroferon Durules). The serum iron method was evaluated and good correlation was found between the serum iron response and the total amount of iron absorbed after an oral dose of iron given in solution or in tablet form. New technique for studying the in-vivo release properties of tablets was presented. Iron tablets labelled with a radio-isotope were given to healthy subjects. The decline of the radioactivity in the tablets was followed by a profile scanning technique applied to different types of iron tablets. The release of iron from the two types of tablets was shown to be slower in vivo than in vitro. It was found that co-administration of antacids and iron tablets led to a marked reduction in the iron absorption and that these drugs should not be administered sumultaneously. A standardized meal markedly decreased the absorbability of iron from iron tablets. The influence of the meal was more marked with rapidly-disintegrating than with slow-release ferrous sulphate tablets. The absorption from rapidly-disintegrating and slow-release ferrous sulphate tablets was compared under practical clinical conditions during an extended treatment period. The studies were performed in healthy subjects, blood donors and patients with iron deficiency anaemia and it was found that the absorption of iron from the slow-release tablets was significantly better than from the rapidly-disintegrating tablets in all three groups of subjects. (author)

Absorption properties of identical atoms

International Nuclear Information System (INIS)

Sancho, Pedro

2013-01-01

Emission rates and other optical properties of multi-particle systems in collective and entangled states differ from those in product ones. We show the existence of similar effects in the absorption probabilities for (anti)symmetrized states of two identical atoms. The effects strongly depend on the overlapping between the atoms and differ for bosons and fermions. We propose a viable experimental verification of these ideas. -- Highlights: •The absorption rates of a pair of identical atoms in product and (anti)symmetrized states are different. •The modifications of the optical properties are essentially determined by the overlapping between the atoms. •The absorption properties differ, in some cases, for bosons and fermions

Phytases for improved iron absorption

DEFF Research Database (Denmark)

Nielsen, Anne Veller Friis; Meyer, Anne S.

2016-01-01

Phytase enzymes present an alternative to iron supplements, because they have been shown to improve iron absorption by means of catalysing the degradation of a potent iron absorption inhibitor: phytic acid. Phytic acid is a hexaphosphate of inositol and is particularly prevalent in cereal grains......, where it serves as a storage molecule for phosphorous. Phytic acid is also associated with minerals. The minerals are bound by chelation to the negatively charged phosphate groups in phytic acid. Phytases catalyse the dephosphorylation of phytic acid, thus releasing bound minerals to make them available...... for absorption. This article presents research on phytase catalysis in gastric conditions and considers potential benefits and drawbacks for using phytases as a food supplement....

Analyzing Water's Optical Absorption

Science.gov (United States)

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.

Uncertainty budgets for liquid waveguide CDOM absorption measurements.

Science.gov (United States)

Lefering, Ina; Röttgers, Rüdiger; Utschig, Christian; McKee, David

2017-08-01

Long path length liquid waveguide capillary cell (LWCC) systems using simple spectrometers to determine the spectral absorption by colored dissolved organic matter (CDOM) have previously been shown to have better measurement sensitivity compared to high-end spectrophotometers using 10 cm cuvettes. Information on the magnitude of measurement uncertainties for LWCC systems, however, has remained scarce. Cross-comparison of three different LWCC systems with three different path lengths (50, 100, and 250 cm) and two different cladding materials enabled quantification of measurement precision and accuracy, revealing strong wavelength dependency in both parameters. Stable pumping of the sample through the capillary cell was found to improve measurement precision over measurements made with the sample kept stationary. Results from the 50 and 100 cm LWCC systems, with higher refractive index cladding, showed systematic artifacts including small but unphysical negative offsets and high-frequency spectral perturbations due to limited performance of the salinity correction. In comparison, the newer 250 cm LWCC with lower refractive index cladding returned small positive offsets that may be physically correct. After null correction of measurements at 700 nm, overall agreement of CDOM absorption data at 440 nm was found to be within 5% root mean square percentage error.

Development of a new free radical absorption capacity assay method for antioxidants: aroxyl radical absorption capacity (ARAC).

Science.gov (United States)

Nagaoka, Shin-ichi; Nagai, Kanae; Fujii, Yuko; Ouchi, Aya; Mukai, Kazuo

2013-10-23

A new free radical absorption capacity assay method is proposed with use of an aroxyl radical (2,6-di-tert-butyl-4-(4'-methoxyphenyl)phenoxyl radical) and stopped-flow spectroscopy and is named the aroxyl radical absorption capacity (ARAC) assay method. The free radical absorption capacity (ARAC value) of each tocopherol was determined through measurement of the radical-scavenging rate constant in ethanol. The ARAC value could also be evaluated through measurement of the half-life of the aroxyl radical during the scavenging reaction. For the estimation of the free radical absorption capacity, the aroxyl radical was more suitable than the DPPH radical, galvinoxyl, and p-nitrophenyl nitronyl nitroxide. The ARAC value in tocopherols showed the same tendency as the free radical absorption capacities reported previously, and the tendency was independent of an oxygen radical participating in the scavenging reaction and of a medium surrounding the tocopherol and oxygen radical. The ARAC value can be directly connected to the free radical-scavenging rate constant, and the ARAC method has the advantage of treating a stable and isolable radical (aroxyl radical) in a user-friendly organic solvent (ethanol). The ARAC method was also successfully applied to a palm oil extract. Accordingly, the ARAC method would be useful in free radical absorption capacity assay of antioxidative reagents and foods.

Buffer-gas-induced absorption resonances in Rb vapor

International Nuclear Information System (INIS)

Mikhailov, Eugeniy E.; Novikova, Irina; Rostovtsev, Yuri V.; Welch, George R.

2004-01-01

We observe transformation of the electromagnetically induced transparency (EIT) resonance into an absorption resonance in a Λ interaction configuration in a cell filled with 87 Rb and a buffer gas. This transformation occurs as one-photon detuning of the coupling fields is varied from the atomic transition. No such absorption resonance is found in the absence of a buffer gas. The width of the absorption resonance is several times smaller than the width of the EIT resonance, and the changes of absorption near these resonances are about the same. Similar absorption resonances are detected in the Hanle configuration in a buffered cell

In vivo evaluation of thiolated poly(acrylic acid) as a drug absorption modulator for MRP2 efflux pump substrates.

Science.gov (United States)

Greindl, Melanie; Föger, Florian; Hombach, Juliane; Bernkop-Schnürch, Andreas

2009-08-01

Recently, several polymers have been reported to modulate drug absorption by inhibition of intestinal efflux pumps such as multidrug resistance proteins (MRPs) and P-glycoprotein (P-gp). The aim of the present study was to evaluate the efficiency of thiolated poly(acrylic acid) (PAA-Cys) to act as a drug absorption modulator for MRP2 efflux pump substrates in vivo, using sulforhodamine 101 as representative MRP2 substrate. In vitro, the permeation-enhancing effect of unmodified PAA and PAA(250)-Cys(,) displaying 580 micromol free thiol groups per gram polymer, was evaluated by using freshly excised rat intestinal mucosa mounted in Ussing-type chambers. In comparison to that of the buffer control, the sulforhodamine 101 transport in the presence of 0.5% unmodified PAA(250) and 0.5% (w/v) PAA(250)-Cys was 1.3- and 4.0-fold improved, respectively. In vivo, sulforhodamine 101 solutions containing 4% (w/v) unmodified PAA(250) or 4% (w/v) thiolated PAA(250) were orally given to rats. The PAA(250)-Cys solution increased the area under the plasma concentration-time curve (AUC(0-12)) of sulforhodamine 101 3.8-fold in comparison to control and 2.2-fold in comparison to unmodified PAA(250). This in vivo study revealed that PAA(250)-Cys significantly increased the oral bioavailability of MRP2 substrate sulforhodamine 101.

Absorption of radionuclide through wounded skin

International Nuclear Information System (INIS)

Kusama, Tomoko; Ogaki, Kazushi; Yoshizawa, Yasuo

1982-01-01

The translocation and absorption of 58 Co(CoCl 2 ) through a wound was investigated experimentally with mice. Physical and chemical skin damages became the objects of the investigation. Abrasion, puncture and incision were made for types of the physical damage. The chemical damage included both acid and alkaline burns. The absorptions of the radionuclide through the contaminated wounds were measured with both a 2 inches NaI(Tl) scintillation detector and an auto well gamma counter at 15,30 and 60 min after the contamination. The radionuclide was hardly absorbed through an undamaged skin. After 30 min, 20 to 40% of the radionuclide applied on the physically damaged skin was absorbed, but was not absorbed through the chemically damaged skin. The absorption rate through the physically damaged skin reached a maximum at 15 to 60 min after the contamination. The velocity of the absorption through the physically damaged skin was 100 times as much as the chemically damaged skin. The absorption rates through the physically and the chemically damaged skins were expressed by the following formulas: A=a(1-e sup(-bt)) and A=a(e sup(bt)-1), where a and b is constant, respectively. (author)

Optical absorption of irradiated carbohydrates

International Nuclear Information System (INIS)

Supe, A.A.; Tiliks, Yu.E.

1994-01-01

The optical absorption spectra of γ-irradiated carbohydrates (glucose, lactose, sucrose, maltose, and starch) and their aqueous solutions were studied. The comparison of the data obtained with the determination of the concentrations of molecular and radical products of radiolysis allows the absorption bands with maxima at 250 and 310 nm to be assigned to the radicals trapped in the irradiated carbohydrates

Microwaves absorption in superconducting materials

International Nuclear Information System (INIS)

Biasi, R.S. de; Fernandes, A.A.R.; Pereira, R.F.R.

1989-01-01

Microwaves absorption measures in two superconductors ceramics systems, Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O are compared with similars datas obtained in the same band of temperature by a conventional method, mutual inductance. The results suggest that the microwaves absorption can be used as single and non-destructive method for investigating the properties of ceramics superconductors. (C.G.C.) [pt

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

Science.gov (United States)

Sjögren, Erik; Thörn, Helena; Tannergren, Christer

2016-06-06

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

Total absorption by degenerate critical coupling

Energy Technology Data Exchange (ETDEWEB)

Piper, Jessica R., E-mail: jrylan@stanford.edu; Liu, Victor; Fan, Shanhui, E-mail: shanhui@stanford.edu [Ginzton Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States)

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.

Gas treating absorption theory and practice

CERN Document Server

Eimer, Dag

2014-01-01

Gas Treating: Absorption Theory and Practice provides an introduction to the treatment of natural gas, synthesis gas and flue gas, addressing why it is necessary and the challenges involved.  The book concentrates in particular on the absorption-desorption process and mass transfer coupled with chemical reaction. Following a general introduction to gas treatment, the chemistry of CO2, H2S and amine systems is described, and selected topics from physical chemistry with relevance to gas treating are presented. Thereafter the absorption process is discussed in detail, column hardware is explain

Enriching Absorptive Capacity through Social Interaction

NARCIS (Netherlands)

Hotho, Jasper J.; Becker-Ritterspach, Florian; Saka-Helmhout, Ayse

Absorptive capacity is frequently highlighted as a key determinant of knowledge transfer within multinational enterprises. But how individual behaviour translates into absorptive capacity at the subsidiary level, and how this is contingent on subsidiaries' social context, remains under-addressed.

Multiphoton absorption coefficients in solids: an universal curve

International Nuclear Information System (INIS)

Brandi, H.S.; Araujo, C.B. de

1983-04-01

An universal curve for the frequency dependence of the multiphoton absorption coefficient is proposed based on a 'non-perturbative' approach. Specific applications have been made to obtain two, three, four and five photons absorption coefficient in different materials. Properly scaling of the two photon absorption coefficient and the use of the universal curve yields results for the higher order absorption coefficients in good agreement with the experimental data. (Author) [pt

Effect of cold plasma treatment on seedling growth and nutrient absorption of tomato

Science.gov (United States)

Jiafeng, JIANG; Jiangang, LI; Yuanhua, DONG

2018-04-01

The effects of cold plasma (CP) treatment on seed germination, seedling growth, root morphology, and nutrient uptake of a tomato were investigated. The results showed that 80 W of CP treatment significantly increased tomato nitrogen (N) and phosphorus (P) absorption by 12.7% and 19.1%, respectively. CP treatment significantly improved the germination potential of tomato seed by 11.1% and the germination rate by 13.8%. Seedling growth characteristics, including total dry weight, root dry weight, root shoot rate, and leaf area, significantly increased after 80 W of CP treatment. Root activity was increased by 15.7% with 80 W of CP treatment, and 12.6% with 100 W of CP treatment. CP treatment (80 W) markedly ameliorated tomato root morphology, and root length, surface area, and volume, which increased 21.3%, 23.6%, and 29.0%, respectively. Our results suggested that CP treatment improved tomato N and P absorption by promoting the accumulation of shoot and root biomass, increasing the leaf area and root activity, and improving the length, surface area, and volume of root growth. Thus, CP treatment could be used in an ameliorative way to improve tomato nutrient absorption.

Interferometric measurement of lines shift in flames in connection with interpretation of lined absorption method in atomic absorption spectroscopy

International Nuclear Information System (INIS)

L'vov, B.V.; Polzik, L.K.; Katskov, D.A.; Kruglikova, L.P.

1975-01-01

This paper is concerned with interferometric measuring of the line shift in flames in the view of interpretation of absorption lines in the atomic absorption spectroscopy. The newly measured line shifts were compared to the known data on Lorentz broadening of the same lines obtained by methods free of the systematic errors. The resonant lines of the alkaline earth elements (Sr, Ca, Ba) were investigated. To reduce self-absorption in the flame the solutions with minimum concentrations of the elements were used. The computation scheme includes the spectrometer apparatus width and line broadening due to the self-absorption. Formulae are given for computing the values studied. Good agreement was observed between the computed and experimental results. Error analysis was performed. It was concluded that any line shifts in the hydrocarbons were correctly taken into an account in the absolute computations of absorption

Anomalous infrared absorption in granular superconductors

International Nuclear Information System (INIS)

Carr, G.L.; Garland, J.C.; Tanner, D.B.

1983-01-01

Granular superconductors are shown to have a far-infrared absorption that is larger when the samples are superconducting than when they are normal. By constrast, theoretical models for these materials predict that when the samples become superconducting, the absorption should decrease

Oligofructose stimulates calcium absorption in adolescents

NARCIS (Netherlands)

Heuvel, E.G.H.M. van den; Muys, T.; Dokkum, W. van; Schaafsma, G.

1999-01-01

Background: In rats, nondigestible oligosaccharides stimulate calcium absorption. Recently, this effect was also found in human subjects. Objective: The objective of the study was to investigate whether consumption of 15 g oligofructose/d stimulates calcium absorption in male adolescents. Design:

Repetitively Mode-Locked Cavity-Enhanced Absorption Spectroscopy (RML-CEAS for Near-Infrared Gas Sensing

Directory of Open Access Journals (Sweden)

Qixin He

2017-12-01

Full Text Available A Pound-Drever-Hall (PDH-based mode-locked cavity-enhanced sensor system was developed using a distributed feedback diode laser centered at 1.53 µm as the laser source. Laser temperature scanning, bias control of the piezoelectric ceramic transducer (PZT and proportional-integral-derivative (PID feedback control of diode laser current were used to repetitively lock the laser modes to the cavity modes. A gas absorption spectrum was obtained by using a series of absorption data from the discrete mode-locked points. The 15 cm-long Fabry-Perot cavity was sealed using an enclosure with an inlet and outlet for gas pumping and a PZT for cavity length tuning. The performance of the sensor system was evaluated by conducting water vapor measurements. A linear relationship was observed between the measured absorption signal amplitude and the H2O concentration. A minimum detectable absorption coefficient of 1.5 × 10–8 cm–1 was achieved with an averaging time of 700 s. This technique can also be used for the detection of other trace gas species by targeting the corresponding gas absorption line.

Optical absorption of carbon-gold core-shell nanoparticles

Science.gov (United States)

Wang, Zhaolong; Quan, Xiaojun; Zhang, Zhuomin; Cheng, Ping

2018-01-01

In order to enhance the solar thermal energy conversion efficiency, we propose to use carbon-gold core-shell nanoparticles dispersed in liquid water. This work demonstrates theoretically that an absorbing carbon (C) core enclosed in a plasmonic gold (Au) nanoshell can enhance the absorption peak while broadening the absorption band; giving rise to a much higher solar absorption than most previously studied core-shell combinations. The exact Mie solution is used to evaluate the absorption efficiency factor of spherical nanoparticles in the wavelength region from 300 nm to 1100 nm as well as the electric field and power dissipation profiles inside the nanoparticles at specified wavelengths (mostly at the localized surface plasmon resonance wavelength). The field enhancement by the localized plasmons at the gold surfaces boosts the absorption of the carbon particle, resulting in a redshift of the absorption peak with increased peak height and bandwidth. In addition to spherical nanoparticles, we use the finite-difference time-domain method to calculate the absorption of cubic core-shell nanoparticles. Even stronger enhancement can be achieved with cubic C-Au core-shell structures due to the localized plasmonic resonances at the sharp edges of the Au shell. The solar absorption efficiency factor can exceed 1.5 in the spherical case and reach 2.3 in the cubic case with a shell thickness of 10 nm. Such broadband absorption enhancement is in great demand for solar thermal applications including steam generation.

Resonant Absorption in GaAs-Based Nanowires by Means of Photo-Acoustic Spectroscopy

Science.gov (United States)

Petronijevic, E.; Leahu, G.; Belardini, A.; Centini, M.; Li Voti, R.; Hakkarainen, T.; Koivusalo, E.; Guina, M.; Sibilia, C.

2018-03-01

Semiconductor nanowires made of high refractive index materials can couple the incoming light to specific waveguide modes that offer resonant absorption enhancement under the bandgap wavelength, essential for light harvesting, lasing and detection applications. Moreover, the non-trivial ellipticity of such modes can offer near field interactions with chiral molecules, governed by near chiral field. These modes are therefore very important to detect. Here, we present the photo-acoustic spectroscopy as a low-cost, reliable, sensitive and scattering-free tool to measure the spectral position and absorption efficiency of these modes. The investigated samples are hexagonal nanowires with GaAs core; the fabrication by means of lithography-free molecular beam epitaxy provides controllable and uniform dimensions that allow for the excitation of the fundamental resonant mode around 800 nm. We show that the modulation frequency increase leads to the discrimination of the resonant mode absorption from the overall absorption of the substrate. As the experimental data are in great agreement with numerical simulations, the design can be optimized and followed by photo-acoustic characterization for a specific application.

Piezoelectricity and absorption of water in biomaterials: bone and tendon

International Nuclear Information System (INIS)

Ghilardi Netto, T.

1973-01-01

A new application of the Fabry-Perot interferometer has been developed, capable of measuring variations in length with a precision of the order of one angstrom. The method has been applied to the determination of some of the inverse piezoelectric coefficients of bovine bone and tendon. The effect of water in these materials was carefully measured and shown to decrease the piezoelectricity. Correlations between the piezoelectricity and length, weight, and volume and surface resistivity were made during the absorption of water [pt

Characterization of cryogenic materials by x-ray absorption methods

International Nuclear Information System (INIS)

Heald, S.M.; Tranquada, J.M.

1985-01-01

X-ray absorption techniques have in recent years been developed into powerful probes of the electronic and structural properties of materials difficult to study by other techniques. In particular, the extended x-ray absorption fine structure (EXAFS) technique can be applied to a variety of cryogenic materials. Three examples are used to demonstrate the power of the technique. The first is the determination of the lattice location of dilute alloying additions such as Ta and Zr in Nb 3 Sn. The Ta additions are shown to reside predominately in Nb lattice sites, while Zr is not uniquely located at either Nb or Sn sites. In addition to structural information, temperature dependent EXAFS studies can be used to determine the rms deviations of atomic bond lengths, providing information about the temperature dependence of interatomic force constants. For Nb 3 Sn deviations are found from simple harmonic behavior at low temperatures which indicate a softening of the Nb-Sn bond strength. The final example is the study of interfacial properties in thin film systems. This is accomplished by making x-ray absorption measurements under conditions of total external reflection of the incident x-rays. As some examples show, this technique has great potential for studying interfacial reactions, a process used in the fabrication of many superconducting materials

Flame emission, atomic absorption and fluorescence spectrometry

International Nuclear Information System (INIS)

Horlick, G.

1980-01-01

Six hundred and thirty references are cited in this review. The information in the review is divided into 12 major areas: books, reviews, and bibliographies; fundamental studies in flames; developments in instrumentation; measurement techniques and procedure; flame emission spectrometry; flame atomic absorption spectrometry; flame molecular absorption spectrometry; electrothermal atomization atomic absorption spectroscopy; hydride generation techniques; graphite furnace atomic emission spectrometry; atomic fluorescence spectrometry; and analytical comparisons

Phytosterol glycosides reduce cholesterol absorption in humans

OpenAIRE

Lin, Xiaobo; Ma, Lina; Racette, Susan B.; Anderson Spearie, Catherine L.; Ostlund, Richard E.

2009-01-01

Dietary phytosterols inhibit intestinal cholesterol absorption and regulate whole body cholesterol excretion and balance. However, they are biochemically heterogeneous and a portion is glycosylated in some foods with unknown effects on biological activity. We tested the hypothesis that phytosterol glycosides reduce cholesterol absorption in humans. Phytosterol glycosides were extracted and purified from soy lecithin in a novel two-step process. Cholesterol absorption was measured in a series ...

Erbium:YAG laser resurfacing increases skin permeability and the risk of excessive absorption of antibiotics and sunscreens: the influence of skin recovery on drug absorption.

Science.gov (United States)

Lee, Woan-Ruoh; Shen, Shing-Chuan; Al-Suwayeh, Saleh A; Li, Yi-Ching; Fang, Jia-You

2012-06-01

While laser skin resurfacing is expected to result in reduced barrier function and increased risk of drug absorption, the extent of the increment has not yet been systematically investigated. We aimed to establish the skin permeation profiles of tetracycline and sunscreens after exposure to the erbium:yttrium-aluminum-garnet (Er:YAG) laser during postoperative periods. Physiological and histopathological examinations were carried out for 5 days after laser treatment on nude mice. Percutaneous absorption of the permeants was determined by an in vitro Franz cell. Ablation depths varied in reaching the stratum corneum (10 μm, 2.5 J/cm²) to approach the epidermis (25 μm, 6.25 J/cm²) and upper dermis (40 μm, 10 J/cm²). Reepithelialization evaluated by transepidermal water loss was complete within 2-4 days and depended on the ablation depth. Epidermal hyperplasia was observed in the 40-μm-treated group. The laser was sufficient to disrupt the skin barrier and allow the transport of the permeants into and across the skin. The laser fluence was found to play an important role in modulating skin absorption. A 25-μm ablation depth increased tetracycline flux 84-fold. A much smaller enhancement (3.3-fold) was detected for tetracycline accumulation within the skin. The laser with different fluences produced enhancement of oxybenzone skin deposition of 3.4-6.4-fold relative to the untreated group. No penetration across the skin was shown regardless of whether titanium dioxide was applied to intact or laser-treated skin. However, laser resurfacing increased the skin deposition of titanium dioxide from 46 to 109-188 ng/g. Tetracycline absorption had recovered to the level of intact skin after 5 days, while more time was required for oxybenzone absorption. The in vivo skin accumulation and plasma concentration revealed that the laser could increase tetracycline absorption 2-3-fold. The experimental results indicated that clinicians should be cautious when determining the

Mechanical and water absorption behaviour of banana/sisal reinforced hybrid composites

International Nuclear Information System (INIS)

Venkateshwaran, N.; ElayaPerumal, A.; Alavudeen, A.; Thiruchitrambalam, M.

2011-01-01

Highlights: → It explores the utilization of waste banana fiber. → Improving the mechanical property by hybridization. → Results show its usefulness to low cost application. -- Abstract: The tensile, flexural, impact and water absorption tests were carried out using banana/epoxy composite material. Initially, optimum fiber length and weight percentage were determined. To improve the mechanical properties, banana fiber was hybridised with sisal fiber. This study showed that addition of sisal fiber in banana/epoxy composites of up to 50% by weight results in increasing the mechanical properties and decreasing the moisture absorption property. Morphological analysis was carried out to observe fracture behaviour and fiber pull-out of the samples using scanning electron microscope.

Electromagnetically induced absorption via incoherent collisions

International Nuclear Information System (INIS)

Yang Xihua; Sheng Jiteng; Xiao Min

2011-01-01

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.

Absorption chillers: Part of the solution

International Nuclear Information System (INIS)

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

Insulin analogues with improved absorption characteristics.

Science.gov (United States)

Brange, J; Hansen, J F; Langkjaer, L; Markussen, J; Ribel, U; Sørensen, A R

1992-01-01

The insulin preparations available today are not ideal for therapy as s.c. injection does not provide a physiological insulin profile. With the aim to improve the absorption properties recombinant DNA technology has been utilized to design novel insulin molecules with changed physico-chemical characteristics and hence altered subcutaneous absorption kinetics. Soluble, long-acting human insulin analogues in which the isoelectric point has been increased from 5.4 to approx. 7 are absorbed very slowly, providing a more constant basal insulin delivery with lower day-to-day variation than present protracted preparations. In addition they have better storage stability. Rapid-acting human insulin analogues with largely reduced self-association are absorbed substantially faster from subcutaneous tissue than current regular insulin and thus are better suited for bolus injection. The absorption kinetics of these analogues have been able to explain the mechanism behind the dose effect on insulin absorption rate.

Studies on absorption coefficient near edge of multi elements

International Nuclear Information System (INIS)

Eisa, M.H.; Shen, H.; Yao, H.Y.; Mi, Y.; Zhou, Z.Y.; Hu, T.D.; Xie, Y.N.

2005-01-01

X-ray absorption near edge structure (XANES) was used to study the near edge mass-absorption coefficients of seven elements, such as, Ti, V, Fe, Co, Ni, Cu and Zn. It is well known that, on the near edge absorption of element, when incident X-ray a few eV change can make the absorption coefficient an order magnitude alteration. So that, there are only a few points mass-absorption coefficient at the near edge absorption and that always average value in published table. Our results showed a wide range of data, the total measured data of mass-absorption coefficient of the seven elements was about 505. The investigation confirmed that XANES is useful technique for multi-element absorption coefficient measurement. Details of experimental methods and results are given and discussed. The experimental work has been performed at Beijing Synchrotron Radiation Facility. The measured values were compared with the published data. Good agreement between experimental results and published data is obtained

Studies on absorption coefficient near edge of multi elements

Science.gov (United States)

Eisa, M. H.; Shen, H.; Yao, H. Y.; Mi, Y.; Zhou, Z. Y.; Hu, T. D.; Xie, Y. N.

2005-12-01

X-ray absorption near edge structure (XANES) was used to study the near edge mass-absorption coefficients of seven elements, such as, Ti, V, Fe, Co, Ni, Cu and Zn. It is well known that, on the near edge absorption of element, when incident X-ray a few eV change can make the absorption coefficient an order magnitude alteration. So that, there are only a few points mass-absorption coefficient at the near edge absorption and that always average value in published table. Our results showed a wide range of data, the total measured data of mass-absorption coefficient of the seven elements was about 505. The investigation confirmed that XANES is useful technique for multi-element absorption coefficient measurement. Details of experimental methods and results are given and discussed. The experimental work has been performed at Beijing Synchrotron Radiation Facility. The measured values were compared with the published data. Good agreement between experimental results and published data is obtained.

Significantly High Modulation Efficiency of Compact Graphene Modulator Based on Silicon Waveguide.

Science.gov (United States)

Shu, Haowen; Su, Zhaotang; Huang, Le; Wu, Zhennan; Wang, Xingjun; Zhang, Zhiyong; Zhou, Zhiping

2018-01-17

We theoretically and experimentally demonstrate a significantly large modulation efficiency of a compact graphene modulator based on a silicon waveguide using the electro refractive effect of graphene. The modulation modes of electro-absorption and electro-refractive can be switched with different applied voltages. A high extinction ratio of 25 dB is achieved in the electro-absorption modulation mode with a driving voltage range of 0 V to 1 V. For electro-refractive modulation, the driving voltage ranges from 1 V to 3 V with a 185-pm spectrum shift. The modulation efficiency of 1.29 V · mm with a 40-μm interaction length is two orders of magnitude higher than that of the first reported graphene phase modulator. The realisation of phase and intensity modulation with graphene based on a silicon waveguide heralds its potential application in optical communication and optical interconnection systems.

Saturable absorption in detonation nanodiamond dispersions

Science.gov (United States)

Vanyukov, Viatcheslav; Mikheev, Gennady; Mogileva, Tatyana; Puzyr, Alexey; Bondar, Vladimir; Lyashenko, Dmitry; Chuvilin, Andrey

2017-07-01

We report on a saturable absorption in aqueous dispersions of nanodiamonds with femtosecond laser pulse excitation at a wavelength of 795 nm. The open aperture Z-scan experiments reveal that in a wide range of nanodiamond particle sizes and concentrations, a light-induced increase of transmittance occurs. The transmittance increase originates from the saturation of light absorption and is associated with a light absorption at 1.5 eV by graphite and dimer chains (Pandey dimer chains). The obtained key nonlinear parameters of nanodiamond dispersions are compared with those of graphene and carbon nanotubes, which are widely used for the mode-locking.

UV laser long-path absorption spectroscopy

Science.gov (United States)

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

Infrared absorption of human breast tissues in vitro

Energy Technology Data Exchange (ETDEWEB)

Liu Chenglin [Department of Physics, Surface Physics Laboratory (National Key laboratory), Synchrotron Radiation Research Center, Fudan University, Shanghai 200433 (China); Physics Department of Yancheng Teachers' College, Yancheng 224002 (China); Zhang Yuan [Department of Physics, Surface Physics Laboratory (National Key laboratory), Synchrotron Radiation Research Center, Fudan University, Shanghai 200433 (China); Yan Xiaohui [Department of Physics, Surface Physics Laboratory (National Key laboratory), Synchrotron Radiation Research Center, Fudan University, Shanghai 200433 (China); Zhang Xinyi [Department of Physics, Surface Physics Laboratory (National Key laboratory), Synchrotron Radiation Research Center, Fudan University, Shanghai 200433 (China) and Shanghai Research Center of Acupuncture and Meridian, Pudong, Shanghai 201203 (China)]. E-mail: xy-zhang@fudan.edu.cn; Li Chengxiang [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029 (China); Yang Wentao [Cancer Hospital, Medical Center, Fudan University, Shanghai 200032 (China); Shi Daren [Cancer Hospital, Medical Center, Fudan University, Shanghai 200032 (China)

2006-07-15

The spectral characteristics of human breast tissues in normal status and during different cancerous stages have been investigated by synchrotron radiation based Fourier transform infrared (SR-FTIR) absorption spectroscopy. Thanks to the excellent synchrotron radiation infrared (IR) source, higher resolving power is achieved in SR-FTIR absorption spectra than in conventional IR absorption measurements. Obvious variations in IR absorption spectrum of breast tissues were found as they change from healthy to diseased, or say in progression to cancer. On the other hand, some specific absorption peaks were found in breast cancer tissues by SR-FTIR spectroscopic methods. These spectral characteristics of breast tissue may help us in early diagnosis of breast cancer.

A measurement of the absorption of liquid argon scintillation light by dissolved nitrogen at the part-per-million level

International Nuclear Information System (INIS)

Jones, B J P; Chiu, C S; Conrad, J M; Ignarra, C M; Katori, T; Toups, M

2013-01-01

We report on a measurement of the absorption length of scintillation light in liquid argon due to dissolved nitrogen at the part-per-million (ppm) level. We inject controlled quantities of nitrogen into a high purity volume of liquid argon and monitor the light yield from an alpha source. The source is placed at different distances from a cryogenic photomultiplier tube assembly. By comparing the light yield from each position we extract the absorption cross section of nitrogen. We find that nitrogen absorbs argon scintillation light with strength of (1.51±0.15) × 10 −4 cm −1 ppm −1 , corresponding to an absorption cross section of (4.99±0.51) × 10 −21 cm 2 molecule −1 . We obtain the relationship between absorption length and nitrogen concentration over the 0 to 50 ppm range and discuss the implications for the design and data analysis of future large liquid argon time projection chamber (LArTPC) detectors. Our results indicate that for a current-generation LArTPC, where a concentration of 2 parts per million of nitrogen is expected, the attenuation length due to nitrogen will be 30±3 meters

Nonresonant absorption of one photon by one atom and resonant absorption of two photons by two atoms

International Nuclear Information System (INIS)

Mizushima, Masataka

1990-01-01

When a radiation field of frequency ω 1 interacts with atoms, etch of which has a transition frequency ω ba =(E b -E a )/h, with ω 1 -ω ba =Δ≠0, nonresonant absorption can take place with probability P 1 inversely proportional to Δ 2 (a pressure broadening). When another radiation field of frequency ω 2 , such that ω 1 +ω 2 =2ω ba, interacts simultaneously with the gas a resonant two-photon absorption can take place in addition to the nonresonant absorption. The probability of this two-photon absorption process, P 2 , is found to be inversely proportional to Δ 4 . If Ω=| | is the Rabi frequency of the transition, it is found that P 2 /(P 1 (Δ)+P 1 (-Δ)) is given by 12 {Ω(-Δ)Ω(-Δ)} 2 / {Δ 2 (Ω(-Δ) 2 + Ω(Δ) 2 )}. (author)

Absorption of hydrogen in vanadium, enhanced by ion bombardment; Ionenbeschussunterstuetzte Absorption des Wasserstoffs in Vanadium

Energy Technology Data Exchange (ETDEWEB)

Paulus, H.; Lammers, M. [Inst. fuer Technologie- und Wissenstransfer, Soest (Germany); Mueller, K.H. [Inst. fuer Technologie- und Wissenstransfer, Soest (Germany)]|[Paderborn Univ. (Gesamthochschule), Soest (Germany). Fachbereich 16 - Elektrische Energietechnik; Kiss, G.; Kemeny, Z. [Technical Univ. Budapest (Hungary)

1998-12-31

Prior to hydrogen implantation into vanadium, the vanadium specimen usually is exposed to an activation process and is then heated at 1 atm hydrogen to temperatures between 500 and 600 C, subsequently cooled down in several steps. Within this temperature range, hydrogen solubility increases with declining temperature. A decisive factor determining hydrogen absorption is the fact that at temperatures above 250 C, oxygen desorbs from the material surface and thus no longer inhibits hydrogen absorption. Therefore a different approach was chosen for the experiments reported: Hydrogen absorption under UHV conditions at room temperature. After the usual activation process, the vanadium surface was cleaned by 5 keV Ar{sup +} ion bombardment. Thus oxygen absorption at the specimen surface (and new reactions with oxygen from the remaining gas) could be avoided, or removed. By means of thermal desorption mass spectrometry (TDMS), hydrogen absorption as a function of argon ion dose was analysed. TDMS measurements performed for specimens treated by ion bombardment prior to H{sup 2} exposure showed two H{sup 2} desorption peaks, in contrast to the profiles measured with specimens not exposed to ion bombardment. It is assumed that the ion bombardment disturbs the crystal structure so that further sites for hydrogen absorption are produced. (orig./CB) [Deutsch] Bei der Beladung von Vandium mit Wasserstoff wird ueblicherweise die Probe nach einer Aktivierungsprozedur bei 1 atm Wasserstoff auf Temperaturen im Bereich von 500 bis 600 C hochgeheizt und danach schrittweise abgekuehlt. In diesem Temperaturbereich nimmt die Wasserstoffloeslichkeit mit abnehmender Temperatur zu. Entscheidend fuer die Beladung ist aber auch die Tatsache, dass bei Temperaturen groesser 250 C Sauerstoff von der Oberflaeche desorbiert und dadurch die Absorption von Wasserstoff nicht mehr blockieren kann. Im Rahmen der hier beschriebenen Untersuchungen sollte die Wasserstoffbeladung unter UHV-Bedingungen bei

Sound absorption in a field of a strong electromagnetic wave in a quantizied magnetic field

International Nuclear Information System (INIS)

Chajkovskij, I.A.

1974-01-01

A coefficient of sound absorption GAMMA in a semiconductor and semi-metal in the quantized magnetic field is calculated for a system exposed to a field of strong electromagnetic radiation. The cases E parallel H and E orthogonal H are considered. Along with the already known strong oscillations of sound absorption in magnetic fields, the absorption spectrum GAMMAsub(par) and GAMMAsub(orth) shows new oscillations representing a manifestation of the quasi-energetic electron spectrum in the field of a strong electromagnetic wave. The oscillation height at E parallel H is modulated by the electromagnetic field. It is shown that the ratio GAMMAsub(par)/GAMMAsub(orth) allows the determination of the effective mass of the carriers

New techniques for optical absorption measurement of implanted nanoparticles in float glass

International Nuclear Information System (INIS)

Okur, I.; Townsend, P.D.; Chandler, P.J.

1999-01-01

New techniques are reported for optical absorption and waveguide loss measurement of copper, gold and silver implanted float glass. Implantations were carried out on the tin face of the float glass since this face is an optical waveguide. Specially made triangle shape masks were used during implantation to study the optical loss-implant length relation. Absorption coefficients were extracted as 2.4 and 1 cm -1 for the gold and silver implants at 633 nm, respectively. These values were found to be implant condition dependent. To analyse the shape of nanoparticles a sandwiched structure was used in an optical absorption measurement set-up in which two guiding faces were put in contact. The sandwiched structure places the colloids at the centre of the optical field distribution rather than on the boundary zone. These experiments have revealed that the copper and the gold particles may have non-spherical shapes, whereas for silver, the formation of spherical nanoparticles is more likely

A Low-Cost Quantitative Absorption Spectrophotometer

Science.gov (United States)

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…

High temperature measurement of water vapor absorption

Science.gov (United States)

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.

Energy absorption build-up factors in teeth

International Nuclear Information System (INIS)

Manjunatha, H.C.; Rudraswamy, B.

2012-01-01

Geometric progression fitting method has been used to compute energy absorption build-up factor of teeth [enamel outer surface, enamel middle, enamel dentin junction towards enamel, enamel dentin junction towards dentin, dentin middle and dentin inner surface] for wide energy range (0.015-15 MeV) up to the penetration depth of 40 mean free path. The dependence of energy absorption build-up factor on incident photon energy, penetration depth, electron density and effective atomic number has also been studied. The energy absorption build-up factors increases with the penetration depth and electron density of teeth. So that the degree of violation of Lambert-Beer (I = I 0 e -μt ) law is less for least penetration depth and electron density. The energy absorption build-up factors for different regions of teeth are not same hence the energy absorbed by the different regions of teeth is not uniform which depends on the composition of the medium. The relative dose of gamma in different regions of teeth is also estimated. Dosimetric implication of energy absorption build-up factor in teeth has also been discussed. The estimated absorption build up factors in different regions of teeth may be useful in the electron spin resonance dosimetry. (author)

The origin of electromagnetically induced absorption

International Nuclear Information System (INIS)

Park, Jong Dae; Hwang, Sung Tae; Lee, Ho Seong; Park, Sung Jong; Cho, Hyuck; Choi, Won Sik

2000-01-01

Recently, there have been a lot of interests in the coherence superposition of atomic states which are formed by laser fields. Coherent population trapping(CTP), electromagnetically induced transparency(EIT), enhancement of the refractive index without absorption, lasing without inversion(LWI), and electromagnetically induced absorption(EIA) are the examples where coherence effects are important. Previously, the spontaneous transfer of the light-induced coherence from the excited level to the ground one was emphasized for the essential ingredient for electromagnetically induced absorption. In this paper, we have considered a case where linearly polarized coupling laser and probe laser are applied to the same degenerated ground and excited levels. We have solved the master equations for density matrix using time varying Hamiltonian and studied the absorption spectra at various conditions. We demonstrate that EIA can be observed without spontaneous transfer of the light-induced coherence in F g = 1 -> F e = 2 D2 transitions of Hydrogen atoms

Narrative absorption

DEFF Research Database (Denmark)

Narrative Absorption brings together research from the social sciences and Humanities to solve a number of mysteries: Most of us will have had those moments, of being totally absorbed in a book, a movie, or computer game. Typically we do not have any idea about how we ended up in such a state. No...

Theory of absorption integrated optical sensor of gaseous materials

Science.gov (United States)

Egorov, A. A.

2010-10-01

The eigen and noneigen (leaky) modes of a three-layer planar integrated optical waveguide are described. The dispersion relation of a three-layer planar waveguide and other dependences are derived, and the cutoff conditions are analyzed. The diagram of propagation constants of the guided and radiation modes of an irregular asymmetric three-layer waveguide and the dependence of the electric field amplitudes of radiation modes of substrate on vertical coordinate in a tantalum integrated optical waveguide are presented. The operating principles of an absorption integrated optical waveguide sensor are investigated. The dependences of sensitivity of an integrated optical waveguide sensor on the sensory cell length, the coupling efficiency of the laser radiation into the waveguide, the absorption cross-section of the studied material, and the level of additive statistical noise are investigated. Some of the prospective areas of application of integrated-optical waveguide sensors are outlined.

Absorption-heat-pump system

Science.gov (United States)

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.

Resonance absorption of ICRF wave in edge plasma

International Nuclear Information System (INIS)

Sugihara, Ryo; Yamanaka, Kaoru.

1987-07-01

An edge plasma is shown to significantly absorb ICRF wave when a resonant triplet, a cutoff-resonance-cutoff triplet, is constructed in the evanescent region. Two-ion-component plasmas in a torus are considered though the plasmas are modeled by a slab in which the density changes linearly along the x-axis. The resonance is a perpendicular-ion-cyclotron resonance, i.e., an Alfven resonance, and is formed when the applied frequency ω is smaller than the local cyclotron frequency, at the edge of the antenna side, of the lighter species of ions. Roughly the absorption rate A b is given by M 2 for M 2 >> S 2 and S 4 for S 2 >> M 2 where M = k y l and S ≅ k z l and l is a scale length of the order of the plasma minor radius and k y and k z are the perpendicular and the parallel components of the wave vector. It is noted that the both quantities, M and S, readily become of the order of unity. Since A b is not very sensitive to the density ratio of the two ion species, a few percent of impurities may cause a significant absorption. As the mass ratio of the two ion species comes close to unity the triplet forms readily. Therefore a D-T plasma seems to suffer more easily this kind of resonance absorption than a D-H plasma. (author)

Dependence of the absorption of pulsed CO2-laser radiation by silane on wavenumber, fluence, pulse duration, temperature, optical path length, and pressure of absorbing and nonabsorbing gases

International Nuclear Information System (INIS)

Blazejowski, J.; Gruzdiewa, L.; Rulewski, J.; Lampe, F.W.

1995-01-01

The absorption of three lines [P(20), 944.2 cm -1 ; P(14), 949.2 cm -1 ; and R(24), 978.5 cm -1 ] of the pulsed CO 2 laser (00 0 1--10 0 0 transition) by SiH 4 was measured at various pulse energy, pulse duration, temperature, optical path length, and pressure of the compound and nonabsorbing foreign gases. In addition, low intensity infrared absorption spectrum of silane was compared with high intensity absorption characteristics for all lines of the pulsed CO 2 laser. The experimental dependencies show deviations from the phenomenological Beer--Lambert law which can be considered as arising from the high intensity of an incident radiation and collisions of absorbing molecules with surroundings. These effects were included into the expression, being an extended form of the Beer--Lambert law, which reasonably approximates all experimental data. The results, except for extending knowledge on the interaction of a high power laser radiation with matter, can help understanding and planning processes leading to preparation of silicon-containing technologically important materials

A transient absorption study of allophycocyanin

Indian Academy of Sciences (India)

Transient dynamics of allophycocyanin trimers and monomers are observed by using the pump-probe, transient absorption technique. The origin of spectral components of the transient absorption spectra is discussed in terms of both kinetics and spectroscopy. We find that the energy gap between the ground and excited ...

In vitro and in vivo percutaneous absorption of retinol from cosmetic formulations: Significance of the skin reservoir and prediction of systemic absorption

International Nuclear Information System (INIS)

Yourick, Jeffrey J.; Jung, Connie T.; Bronaugh, Robert L.

2008-01-01

The percutaneous absorption of retinol (Vitamin A) from cosmetic formulations was studied to predict systemic absorption and to understand the significance of the skin reservoir in in vitro absorption studies. Viable skin from fuzzy rat or human subjects was assembled in flow-through diffusion cells for in vitro absorption studies. In vivo absorption studies using fuzzy rats were performed in glass metabolism cages for collection of urine, feces, and body content. Retinol (0.3%) formulations (hydroalcoholic gel and oil-in-water emulsion) containing 3 H-retinol were applied and absorption was measured at 24 or 72 h. All percentages reported are % of applied dose. In vitro studies using human skin and the gel and emulsion vehicles found 0.3 and 1.3% retinol, respectively, in receptor fluid at 24 h. Levels of absorption in the receptor fluid increased over 72 h with the gel and emulsion vehicles. Using the gel vehicle, in vitro rat skin studies found 23% in skin and 6% in receptor fluid at 24 h, while 72-h studies found 18% in skin and 13% in receptor fluid. Thus, significant amounts of retinol remained in rat skin at 24 h and decreased over 72 h, with proportional increases in receptor fluid. In vivo rat studies with the gel found 4% systemic absorption of retinol after 24 h and systemic absorption did not increase at 72 h. Retinol remaining in rat skin after in vivo application was 18% and 13% of the applied dermal dose after 24 and 72 h, respectively. Similar observations were made with the oil-in water emulsion vehicle in the rat. Retinol formed a reservoir in rat skin both in vivo and in vitro. Little additional retinol was bioavailable after 24 h. Comparison of these in vitro and in vivo results for absorption through rat skin indicates that the 24-h in vitro receptor fluid value accurately estimated 24-h in vivo systemic absorption. Therefore, the best single estimate of retinol systemic absorption from in vitro human skin studies is the 24-h receptor fluid

MNC Knowledge Transfer, Subsidiary Absorptive Capacity and HRM

DEFF Research Database (Denmark)

Minbaeva, Dana; Pedersen, Torben; Björkman, Ingmar

2014-01-01

Based on a sample of 169 subsidiaries of multinational corporations (MNCs) operating in the USA, Russia, and Finland, this paper investigates the relationship between MNC subsidiary HRM practices, absorptive capacity and knowledge transfer. First, we examine the relationship between the application...... of specific HRM practices and the level of the absorptive capacity. Second, we suggest that absorptive capacity should be conceptualized as being comprised of both employees’ ability and motivation. Further, results indicate that both ability and motivation (absorptive capacity) are needed to facilitate...

Transdermic absorption of Melagenina II

International Nuclear Information System (INIS)

Hernandez Gonzalez, I.; Martinez Lopez, B.; Ruiz Pena, M.; Caso Pena, R.

1997-01-01

The transdermic absorption of Melagenina II (MII) was evaluated. MII was a labelled with 125I by the yodogen method and purified by column chromatography with Sephadex LH-20 in ethanol: water (7:3). In vitro absorption of ( 125I ) - MII thought human skin was carried out in Keshary-Chien modified diffusion cells. Tape stripping method was applied after 24 hours to evaluate the accumulated activity in dermis and epidermis. In vivo assays were performed in Sprague Dawley rats to analyze absorption of MII until 24 hours after a single application and for five days a low penetrability of the drug while in vivo there were not found blood levels significantly greater than zero , nevertheless and important amount of radioactivity was found in feces and urine. The activity was concentrated mainly in the application site in both models

Architecture for Absorption Based Heaters

Science.gov (United States)

Moghaddam, Saeed; Chugh, Devesh

2018-04-24

An absorption based heater is constructed on a fluid barrier heat exchanging plate such that it requires little space in a structure. The absorption based heater has a desorber, heat exchanger, and absorber sequentially placed on the fluid barrier heat exchanging plate. The vapor exchange faces of the desorber and the absorber are covered by a vapor permeable membrane that is permeable to a refrigerant vapor but impermeable to an absorbent. A process fluid flows on the side of the fluid barrier heat exchanging plate opposite the vapor exchange face through the absorber and subsequently through the heat exchanger. The absorption based heater can include a second plate with a condenser situated parallel to the fluid barrier heat exchanging plate and opposing the desorber for condensation of the refrigerant for additional heating of the process fluid.

Mercury absorption in aqueous hypochlorite

International Nuclear Information System (INIS)

Zhao, L.L.; Rochelle, G.T.

1999-01-01

The absorption of elemental Hg vapor into aqueous hypochlorite was measured in a stirred tank reactor at 25 and 55C. NaOCl strongly absorbs Hg even at high pH. Low pH, high Cl - and high-temperature favor mercury absorption. Aqueous free Cl 2 was the active species that reacted with mercury. However, chlorine desorption was evident at high Cl - and pH 15 M -1 s -1 at 25C and 1.4x10 17 M -1 s -1 at 55C. Gas-phase reaction was observed between Hg and Cl 2 on apparatus surfaces. Strong mercury absorption in water was also detected with Cl 2 present. Results indicate that the chlorine concentration, moisture, and surface area contribute positively to mercury removal. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

Quantum of optical absorption in two-dimensional semiconductors.

Science.gov (United States)

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.

Energy absorption and failure response of silk/epoxy composite square tubes: Experimental

DEFF Research Database (Denmark)

Oshkovr, Simin Ataollahi; Taher, Siavash Talebi; A. Eshkoor, Rahim

2012-01-01

This paper focuses on natural silk/epoxy composite square tubes energy absorption and failure response. The tested specimens were featured by a material combination of different lengths and same numbers of natural silk/epoxy composite layers in form of reinforced woven fabric in thermosetting epoxy...

Absorption of proteins and amino acids

International Nuclear Information System (INIS)

Jeejeebhoy, K.N.

1976-01-01

Although the absorption of proteins and amino acids is an important issue in nutrition, its measurement is not common because of the methodological difficulties. Complications are attributable in particular to the magnitude of endogenous protein secretion and to the diversity of absorption mechanisms for amino acids either as individual units or as peptides. Methods for studying absorption include balance techniques, tolerance tests, tracer techniques using proteins or amino acids labelled with 131 I, 3 H, or 15 N, intestinal perfusion studies, and others; they must be selected according to the nature of the information sought. Improvements over the current methods would be useful. (author)

Gastrointestinal absorption of uranium in man

International Nuclear Information System (INIS)

Larsen, R.P.; Orlandini, K.A.

1984-01-01

A method has been established for determining the fractional absorption of uranium directly in man. Measurements are made of the urinary excretion rates of uranium for individuals whose drinking water has a high 234 U to 238 U activity ratio and is the primary source of 234 U in their diets. For two individuals, the values obtained for the fractional absorption of 234 U were 0.004 and 0.006. The values obtained for the fractional absorption of 238 U, using a literature value for the 238 U intake from food, were 0.008 and 0.015. The present ICRP value is 0.20. 7 references, 1 table

Water Absorption Behavior of Hemp Hurds Composites

Science.gov (United States)

Stevulova, Nadezda; Cigasova, Julia; Purcz, Pavol; Schwarzova, Ivana; Kacik, Frantisek; Geffert, Anton

2015-01-01

In this paper, water sorption behavior of 28 days hardened composites based on hemp hurds and inorganic binder was studied. Two kinds of absorption tests on dried cube specimens in deionized water bath at laboratory temperature were performed. Short-term (after one hour water immersion) and long-term (up to 180 days) water absorption tests were carried out to study their durability. Short-term water sorption behavior of original hemp hurds composites depends on mean particle length of hemp and on binder nature. The comparative study of long-term water sorption behavior of composites reinforced with original and chemically modified hemp hurds in three reagents confirmed that surface treatment of filler influences sorption process. Based on evaluation of sorption curves using a model for composites based on natural fibers, diffusion of water molecules in composite reinforced with original and chemically modified hemp hurds is anomalous in terms of the Fickian behavior. The most significant decrease in hydrophility of hemp hurds was found in case of hemp hurds modified by NaOH and it relates to change in the chemical composition of hemp hurds, especially to a decrease in average degree of cellulose polymerization as well as hemicellulose content.

Generation of ultra-wide and flat optical frequency comb based on electro absorption modulator

Science.gov (United States)

Ujjwal; Thangaraj, Jaisingh

2018-05-01

A novel technique is proposed for the generation of ultra-wide and flat optical frequency comb (OFC) based on serially cascading three stages of electro absorption modulators (EAMs) through sinusoidal radio frequency (RF) signals by setting frequencies at f GHz, f/2 GHz and f/4 GHz. Here, the first stage acts as subcarrier generator, the second stage acts as subcarrier doubler, and the third stage acts as subcarrier quadrupler. In addition, a higher number of subcarriers can easily be generated by adjusting the driving sinusoidal RF signal. In this paper, cascading three stages of EAMs driven by 50 GHz, 25 GHz and 12.5 GHz clock sources, we obtain 272 subcarriers with spacing of 2.5 GHz and power deviation within 1 dB. Theoretical analysis of serially cascaded EAMs for subcarrier generation is also investigated. Principal analysis and simulation of this technique are demonstrated.

Evidence for pion absorption on four nucleons

International Nuclear Information System (INIS)

Rzehorz, B.; Backenstoss, G.; Dzemidzic, M.; Zagreb Univ.; Furic, M.; Zagreb Univ.; Hoffart, A.; Petkovic, T.; Zagreb Univ.; Ullrich, H.; Weyer, H.J.; Weiser, D.; Wildi, M.

1996-01-01

Experimental spectra from the coincident detection of three nucleons after the pion absorption in 4 He are displayed. The presence of a mechanism with four nucleons participating in the absorption process is made obvious. The total cross-sections for this absorption mode are: σ 4NA abs =(1.0±0.2)mb at T π =120 MeV and σ 4NA abs =(2.18± 0.65) mb at T π =210 MeV. (orig.)

Hopping absorption edge in silicon inversion layers

International Nuclear Information System (INIS)

Kostadinov, I.Z.

1983-09-01

The low frequency gap observed in the absorption spectrum of silicon inversion layers is related to the AC variable range hopping. The frequency dependence of the absorption coefficient is calculated. (author)

Absorption in one-dimensional metallic-dielectric photonic crystals

International Nuclear Information System (INIS)

Yu Junfei; Shen Yifeng; Liu Xiaohan; Fu Rongtang; Zi Jian; Zhu Zhiqiang

2004-01-01

We show theoretically that the absorption of one-dimensional metallic-dielectric photonic crystals can be enhanced considerably over the corresponding constituent metal. By properly choosing the structural and material parameters, the absorption of one-dimensional metallic-dielectric photonic crystals can be enhanced by one order of magnitude in the visible and in the near infrared regions. It is found that the absorptance of such photonic crystals increases with increasing number of periods. Rules on how to obtain a absorption enhancement in a certain frequency range are discussed. (letter to the editor)

Phytosterol glycosides reduce cholesterol absorption in humans

Science.gov (United States)

Lin, Xiaobo; Ma, Lina; Racette, Susan B.; Anderson Spearie, Catherine L.; Ostlund, Richard E.

2009-01-01

Dietary phytosterols inhibit intestinal cholesterol absorption and regulate whole body cholesterol excretion and balance. However, they are biochemically heterogeneous and a portion is glycosylated in some foods with unknown effects on biological activity. We tested the hypothesis that phytosterol glycosides reduce cholesterol absorption in humans. Phytosterol glycosides were extracted and purified from soy lecithin in a novel two-step process. Cholesterol absorption was measured in a series of three single-meal tests given at intervals of 2 wk to each of 11 healthy subjects. In a randomized crossover design, participants received ∼300 mg of added phytosterols in the form of phytosterol glycosides or phytosterol esters, or placebo in a test breakfast also containing 30 mg cholesterol-d7. Cholesterol absorption was estimated by mass spectrometry of plasma cholesterol-d7 enrichment 4–5 days after each test. Compared with the placebo test, phytosterol glycosides reduced cholesterol absorption by 37.6 ± 4.8% (P lecithin are bioactive in humans and should be included in methods of phytosterol analysis and tables of food phytosterol content. PMID:19246636

Absorption Mode FT-ICR Mass Spectrometry Imaging

Energy Technology Data Exchange (ETDEWEB)

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

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.

Design considerations regarding an atomizer for multi-element electrothermal atomic absorption spectrometry

Energy Technology Data Exchange (ETDEWEB)

Katskov, Dmitri A., E-mail: katskovda@tut.ac.za [Department of Chemistry, Tshwane University of Technology, Private Bag X680, Pretoria 0001 (South Africa); Sadagov, Yuri M. [All-Russian Scientific Research Institute of Optical and Physical Measurements (VNIIOFI), Ozernaya St. 46, Moscow 119361 (Russian Federation)

2011-06-15

The methodology of simultaneous multi-element electrothermal atomic absorption spectrometry (ETAAS-Electrothermal Atomic Absorption Spectrometry) stipulates rigid requirements to the design and operation of the atomizer. It must provide high degree of atomization for the group of analytes, invariant respective to the vaporization kinetics and heating ramp residence time of atoms in the absorption volume and absence of memory effects from major sample components. For the low resolution spectrometer with a continuum radiation source the reduced compared to traditional ETAAS (Electrothermal Atomic Absorption Spectrometry) sensitivity should be, at least partially, compensated by creating high density of atomic vapor in the absorption pulse. The sought-for characteristics were obtained for the 18 mm in length and 2.5 mm in internal diameter longitudinally heated graphite tube atomizer furnished with 2-4.5 mg of ring shaped carbon fiber yarn collector. The collector located next to the sampling port provides large substrate area that helps to keep the sample and its residue in the central part of the tube after drying. The collector also provides a 'platform' effect that delays the vaporization and stipulates vapor release into absorption volume having already stabilized gas temperature. Due to the shape of external surface of the tube, presence of collector and rapid (about 10 {sup o}C/ms) heating, an inverse temperature distribution along the tube is attained at the beginnings of the atomization and cleaning steps. The effect is employed for cleaning of the atomizer using the set of short maximum power heating pulses. Preparation, optimal maintenance of the atomizer and its compliance to the multi-element determination requirements are evaluated and discussed. The experimental setup provides direct simultaneous determination of large group of element within 3-4 order concentration range. Limits of detection are close to those for sequential single element

Simulation of absorption refrigeration system for automobile application

Directory of Open Access Journals (Sweden)

Ramanathan Anand

2008-01-01

Full Text Available An automotive air-conditioning system based on absorption refrigeration cycle has been simulated. This waste heat driven vapor absorption refrigeration system is one alternate to the currently used vapour compression refrigeration system for automotive air-conditioning. Performance analysis of vapor absorption refrigeration system has been done by developing a steady-state simulation model to find the limitation of the proposed system. The water-lithium bromide pair is used as a working mixture for its favorable thermodynamic and transport properties compared to the conventional refrigerants utilized in vapor compression refrigeration applications. The pump power required for the proposed vapor absorption refrigeration system was found lesser than the power required to operate the compressor used in the conventional vapor compression refrigeration system. A possible arrangement of the absorption system for automobile application is proposed.

Acoustic absorption behaviour of an open-celled aluminium foam

CERN Document Server

Han Fu Sheng; Zhao Yu Yuan; Gibbs, B

2003-01-01

Metal foams, especially close-celled foams, are generally regarded as poor sound absorbers. This paper studies the sound absorption behaviour of the open-celled Al foams manufactured by the infiltration process, and the mechanisms involved. The foams show a significant improvement in sound absorption compared with close-celled Al foams, because of their high flow resistance. The absorption performance can be further enhanced, especially at low frequencies, if the foam panel is backed by an appropriate air gap. Increasing the air-gap depth usually increases both the height and the width of the absorption peak and shifts the peak towards lower frequencies. The foam samples with the smallest pore size exhibit the best absorption capacities when there is no air gap, whereas those with medium pore sizes have the best overall performance when there is an air gap. The typical maximum absorption coefficient, noise reduction coefficient and half-width of the absorption peak are 0.96-0.99, 0.44-0.62 and 1500-3500 Hz, r...

Automatic Locking of Laser Frequency to an Absorption Peak

Science.gov (United States)

Koch, Grady J.

2006-01-01

An electronic system adjusts the frequency of a tunable laser, eventually locking the frequency to a peak in the optical absorption spectrum of a gas (or of a Fabry-Perot cavity that has an absorption peak like that of a gas). This system was developed to enable precise locking of the frequency of a laser used in differential absorption LIDAR measurements of trace atmospheric gases. This system also has great commercial potential as a prototype of means for precise control of frequencies of lasers in future dense wavelength-division-multiplexing optical communications systems. The operation of this system is completely automatic: Unlike in the operation of some prior laser-frequency-locking systems, there is ordinarily no need for a human operator to adjust the frequency manually to an initial value close enough to the peak to enable automatic locking to take over. Instead, this system also automatically performs the initial adjustment. The system (see Figure 1) is based on a concept of (1) initially modulating the laser frequency to sweep it through a spectral range that includes the desired absorption peak, (2) determining the derivative of the absorption peak with respect to the laser frequency for use as an error signal, (3) identifying the desired frequency [at the very top (which is also the middle) of the peak] as the frequency where the derivative goes to zero, and (4) thereafter keeping the frequency within a locking range and adjusting the frequency as needed to keep the derivative (the error signal) as close as possible to zero. More specifically, the system utilizes the fact that in addition to a zero crossing at the top of the absorption peak, the error signal also closely approximates a straight line in the vicinity of the zero crossing (see Figure 2). This vicinity is the locking range because the linearity of the error signal in this range makes it useful as a source of feedback for a proportional + integral + derivative control scheme that

Absorption of ultraviolet radiation by antarctic phytoplankton

Energy Technology Data Exchange (ETDEWEB)

Vernet, M.; Mitchell, B.G. (Univ. of California-San Diego, La Jolla (United States))

1990-01-09

Antarctic phytoplankton contain UV-absorbing compounds that may block damaging radiation. Compounds that absorb from 320-340 nm were observed in spectral absorption of both particulates and in methanol extracts of the particulates. The decrease in the total concentration of these UV compounds with respect to chlorophyll a, as measured by the ratio of in vitro absorption at 335 nm to absorption at 665 nm is variable and decreases with depth. We observed up to 5-fold decrease in this ratio for samples within the physically mixes surface layer. The absorption of UV radiation in methanol extracts, which peaks from 320 to 340 nm, may be composed of several compounds. Shifts in peak absorption with depth (for example, from 331 nm at surface to 321 nm at 75 m), may be interpreted as a change in composition. Ratios of protective yellow xanthophylls (diadinoxanthin + diatoxanthin) to photosynthetic fucoxanthin-like pigments have highest values in surface waters. As these pigments also absorb in the near UV, their function might extend to protection as well as utilization of UV radiation for photosynthesis. We document strong absorption in the UV from 320-330 nm for Antarctic marine particulates. Below this region of the solar energy spectrum, absolute energy levels of incident radiation drop off dramatically. Only wavelengths shorter than about 320 nm will be significantly enhanced due to ozone depletion. If the absorption we observed serves a protective role for phytoplankton photosynthesis, it appears the peak band is in the region where solar energy increases rapidly, and not in the region where depletion would cause significant variations in absolute flux.

Infrared absorption in PbTe single crystals

International Nuclear Information System (INIS)

Kudykina, T.A.

1982-01-01

A group-theoretical analysis is conducted to select rules for optical transitions between bands in PbTe single crystals. It is shown that transitions between valence bands which are near a forbidden band are also forbidden. The extra absorption observed in p-PbTe and p-Pbsub(1-x)Snsub(x)Te in the region between the self-absorption edge and the free-carrier absorption edge is probably connected with transitions between one of valence bands and the p-state of the impurity

Optical absorption in a thin nickel wire

OpenAIRE

INAGAKI, Takashi; Goudonnet, J.P.; ARAKAWA, E.T.

1986-01-01

Absorption of a 633-nm phonton in a cylindrical nickel wire with diameter 13 m was measured by a photoacoustic method as a function of angle of phonton incidence . A good photoacoustic signal was obtained with a 6-m W He-Ne laser as a light source without employing focusing optics. The absorption measured for p-polarized phontons was found to be in good agreement with geometrical optics calculation. For s-polarized light, however, significant excess absorption was found for >35.

Temperature-dependent optical absorption of SrTiO3

International Nuclear Information System (INIS)

Kok, Dirk J.; Irmscher, Klaus; Naumann, Martin; Guguschev, Christo; Galazka, Zbigniew; Uecker, Reinhard

2015-01-01

The optical absorption edge and near infrared absorption of SrTiO 3 were measured at temperatures from 4 to 1703 K. The absorption edge decreases from 3.25 eV at 4 K to 1.8 eV at 1703 K and is extrapolated to approximately 1.2 eV at the melting point (2350 K). The transmission in the near IR decreases rapidly above 1400 K because of free carrier absorption and is about 50% of the room temperature value at 1673 K. The free carriers are generated by thermal excitation of electrons over the band gap and the formation of charged vacancies. The observed temperature-dependent infrared absorption can be well reproduced by a calculation based on simple models for the intrinsic free carrier concentration and the free carrier absorption coefficient. The measured red shift of the optical absorption edge and the rising free carrier absorption strongly narrow the spectral range of transmission and impede radiative heat transport through the crystal. These effects have to be considered in high temperature applications of SrTiO 3 -based devices, as the number of free carriers rises considerably, and in bulk crystal growth to avoid growth instabilities. Temperature dependent optical absorption edge of SrTiO 3 , measured, fitted, and extrapolated to the melting point. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Laser Absorption by Over-Critical Plasmas

Science.gov (United States)

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.

Pathlength Determination for Gas in Scattering Media Absorption Spectroscopy

Directory of Open Access Journals (Sweden)

Liang Mei

2014-02-01

Full Text Available Gas in scattering media absorption spectroscopy (GASMAS has been extensively studied and applied during recent years in, e.g., food packaging, human sinus monitoring, gas diffusion studies, and pharmaceutical tablet characterization. The focus has been on the evaluation of the gas absorption pathlength in porous media, which a priori is unknown due to heavy light scattering. In this paper, three different approaches are summarized. One possibility is to simultaneously monitor another gas with known concentration (e.g., water vapor, the pathlength of which can then be obtained and used for the target gas (e.g., oxygen to retrieve its concentration. The second approach is to measure the mean optical pathlength or physical pathlength with other methods, including time-of-flight spectroscopy, frequency-modulated light scattering interferometry and the frequency domain photon migration method. By utilizing these methods, an average concentration can be obtained and the porosities of the material are studied. The last method retrieves the gas concentration without knowing its pathlength by analyzing the gas absorption line shape, which depends upon the concentration of buffer gases due to intermolecular collisions. The pathlength enhancement effect due to multiple scattering enables also the use of porous media as multipass gas cells for trace gas monitoring. All these efforts open up a multitude of different applications for the GASMAS technique.

Interplay between absorption, dispersion and refraction in high-order harmonic generation

International Nuclear Information System (INIS)

Dachraoui, H; Helmstedt, A; Bartz, P; Michelswirth, M; Mueller, N; Pfeiffer, W; Heinzmann, U; Auguste, T; Salieres, P

2009-01-01

We report a detailed experimental and theoretical study on high-order harmonic generation of a femtosecond Ti-sapphire laser focused at an intensity of around 10 15 W cm -2 onto a high-pressure (50-210 mbar) neon gas cell of variable length (1-3 mm). Using thorough three-dimensional simulations, we discuss the interplay between the different factors influencing the harmonic-generation efficiency, i.e. phase matching determined by the electronic and atomic dispersions, re-absorption of the harmonics by the medium and refraction of the generating laser beam. Generically, we find that, in our generation conditions, the emission yield of harmonics from the plateau region of the spectrum is absorption limited, whereas the emission from harmonics in the cut-off is strongly reduced due to both electron dispersion and ionization-induced refraction of the laser beam. A good agreement between the numerical results and the experimental data is obtained for the harmonic yield dependence on the various generation parameters (gas pressure, medium length and laser intensity).

Electromagnetic wave absorption properties of composites with ultrafine hollow magnetic fibers

Energy Technology Data Exchange (ETDEWEB)

Yi, Jin Woo [Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (BK21 Granted Program), 291 Daehak-ro, Yuseong-gu, Daejeon (Korea, Republic of); Composites Research Center, Korea Institute of Materials Science, 66 Sang-nam-dong, Changwon, Gyeongnam (Korea, Republic of); Lee, Sang Bok; Kim, Jin Bong; Lee, Sang Kwan [Composites Research Center, Korea Institute of Materials Science, 66 Sang-nam-dong, Changwon, Gyeongnam (Korea, Republic of); Park, O Ok, E-mail: oopark@kaist.ac.kr [Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (BK21 Granted Program), 291 Daehak-ro, Yuseong-gu, Daejeon (Korea, Republic of); Department of Energy Systems Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 50-1, Sang-ri, Hyeongpung-myeon, Dalseong-gun, Daegu 711-873 (Korea, Republic of)

2014-06-01

Ultrafine hollow magnetic fibers were prepared by electroless plating using hydrolyzed polyester fiber as a sacrificial substrate. These hollow fibers can be served for lightweight and efficient electromagnetic (EM) absorbing materials. As observed from SEM and EDS analysis, hollow structures consisting of Ni inner layer and Fe or Fe–Co outer layer were obtained. By introducing Co onto Fe, oxidation of the Fe layer was successfully prevented making it possible to enhance the complex permeability compared to a case in which only Fe was used. Polymeric composites containing the hollow fibers with different weight fractions and fiber lengths were prepared by a simple mixing process. The electromagnetic wave properties of the composites were measured by a vector network analyzer and it was found that the hollow magnetic fibers show a clear resonance peak of the complex permittivity around the X-band range (8–12 GHz) and the resonance frequency strongly depends on the fiber concentration and length. A possible explanation for the unique resonance is that the hollow fibers possess relatively low electrical conductivity and a long mean free path due to their oxidized phase and hollow structure. The calculated EM wave absorption with the measured EM wave properties showed that the composite containing 30 wt% hollow Ni/Fe–Co (7:3) fibers in length of 180 μm exhibited multiple absorbance peaks resulting in a broad absorption bandwidth of 4.2 GHz. It is obvious that this multiple absorbance is attributed to the resonance characteristic of the composite. - Highlights: • The ultrafine hollow fibers consist of inner Ni layer (∼100 nm) and outer Fe or Fe–Co layer (500–700 nm). • Composites with the fibers show a high permittivity as well as permeability at low weight fractions (10–30 wt%). • The composites show a permittivity resonance and the resonance frequency can be controlled by fiber content and length. • The composite absorber exhibits a double

Water absorption of superabsorbent polymers in a cementitious environment

DEFF Research Database (Denmark)

Jensen, Ole Mejlhede

2011-01-01

This paper focuses on the water absorption of superabsorbent polymers in a cementitious environment. The paper discusses different techniques to measure the water absorption capacity, and in particular it describes a technique which enables a simple and quick estimation of the water absorption...... capacity in a cementitious environment. The challenges met in defining the concept of water absorption capacity are treated, and the appropriateness of different types of superabsorbent polymers is also briefly dealt with. The concept “water absorption capacity” and its measurement seem straightforwardly...... simple, but a closer examination of the topic discloses many, significant difficulties. However, given proper cautiousness it is possible both to quickly estimate the water absorption capacity through a simple measurement as well as to examine how it will be influenced by different factors....

Total photon absorption

International Nuclear Information System (INIS)

Carlos, P.

1985-01-01

Experimental methods using real photon beams for measurements of total photonuclear absorption cross section σ(Tot : E/sub γ/) are recalled. Most recent σ(Tot : E/sub γ/)results for complex nuclei and in the nucleon resonance region are presented

Absorption by water vapour in the 1 to 2 μm region

International Nuclear Information System (INIS)

Smith, K.M.; Ptashnik, I.; Newnham, D.A.; Shine, K.P.

2004-01-01

The near-IR (in the range 5000-10 000 cm -1 , 1-2 μm) bands of water vapour have been measured in absorption in the laboratory at sub-Doppler spectral resolution (up to 0.0054 cm -1 after numerical apodisation) by Fourier transform spectroscopy. Measurements have been made at 296 K on pure water vapour (at pressures between 2 and 20 hPa) and mixtures of water and air (at total pressures of 100 and 1000 hPa), at optical path lengths in the range 0.26-9.75 m. Measured absorption intensities have been compared with values calculated using the HITRAN 2000 molecular database. These comparisons indicate that the intensities of the 2ν(1.4 μm) and 2ν+δ(1.14 μm) bands are underestimated in HITRAN 2000 by approximately 15% and 20%, respectively, for pure water vapour measurements, and 12% for both bands in the case of water-air mixtures. The ν+δ (1.86 μm) band is in good agreement (0.4% for pure water vapour and less than 6% for mixtures with air) with HITRAN 2000. For typical atmospheric conditions, these absorption bands are sufficiently strong that radiation is fully absorbed at wavelengths in the region of the band centres. Hence the extra absorption that has been identified has only a modest impact (0.16 W m -2 or about 0.2%) on the global-mean clear-sky absorption of solar radiation. The impact in the upper troposphere is several times larger

Unveiling the Microfoundations of Absorptive Capacity

DEFF Research Database (Denmark)

Distel, Andreas Philipp

2017-01-01

to absorptive capacity at the organizational level and that this relationship is mediated through a microlevel process. The findings reveal that knowledge workers’ cognitive process of perspective taking and their creative behavior are important microfoundations of absorptive capacity. Moreover, the results...... emphasize the critical role of key employees in explaining firm-level heterogeneity in building organizational capabilities....

Sustainable Absorption Panels from Agricultural Wastes

Directory of Open Access Journals (Sweden)

Ismail F.Z.

2014-01-01

Full Text Available Noise has become a serious environmental problem and there are demands for alternative sustainable materials which capable to reduce the noise level at various frequency ranges. Therefore, the aim of this research is to study the potential of turning the agricultural waste and waste paper into a sound absorption panel. For the purpose of this study, combination of two materials was under studied; coconut coir fibre from agriculture waste and shredded waste paper from the office. There were two main objective of the research; first is to develop absorption panels from coconut coir powder that available locally with a combination of shredded paper at different percentage of mixture. Second objective is to identify the absorption rate of the panels. The study encompasses the fabrication of the particle board using the coconut husk powder mix with shredded waste paper and using the gypsum powder as the binder for the two materials. Four acoustic panels of size 0.5m x 0.5m and 0.012 m thick were fabricated with different mix ratio; 25% of coconut coir powder mixed with 75% of shredded waste papers for sample 1, 50% both of the material for sample 2, 75% of coconut coir powder mixed with 25% of shredded waste paper for sample 3, and lastly 100% of coconut coir powder for sample 4. The absorption coefficient of the panels was tested in a reverberation chamber and in accordance with ISO 354:1985 standards. Based on the results, sample 1 gave the highest absorption coefficient compared to sample 2, 3 and 4. It can be concluded that the acoustic panel made from a mixture of 25% coconut coir powder with 75% shredded waste paper provided higher absorption coefficient compared to the performance of the other samples. This might be caused by the size of the coir powder which is very small, creating less void space in between the panel and thus causing it to absorb less sound. Since sound absorption is very much affected by the availability of void space of

Absorption spectrum of Iodine around 5915 A

International Nuclear Information System (INIS)

1990-01-01

The iodine absorption spectrum around 5915 A is of interest for many authors especially the hyperfine structure of the iodine line. Lodine absorption spectrum was obtained due to the interaction of iodine vapour with dye laser [(R6G) (0.5A) scanning range around 5915 A] which is pumped by(Ar + )laser absorption spectrum. The decrease in the peak of the transmission line around 5915 A shows the signal futher decreased by heating the iodine cell. This analysis has been done using a monochromator

Optical absorption in a thin nickel wire

International Nuclear Information System (INIS)

Inagaki, T.; Goudonnet, J.P.; Arakawa, E.T.

1986-01-01

Absorption of a 633-nm photon in a cylindrical nickel wire with diameter 13 μm was measured by a photoacoustic method as a function of angle of photon incidence theta. A good photoacoustic signal was obtained with a 6-mW He-Ne laser as a light source without employing focusing optics. The absorption measured for p-polarized photons was found to be in good agreement with geometrical optics calculation. For s-polarized light, however, significant excess absorption was found for theta > 35 0

Dissipative Vortex Solitons in Defocusing Media with Spatially Inhomogeneous Nonlinear Absorption

Science.gov (United States)

Lai, Xian-Jing; Cai, Xiao-Ou; Zhang, Jie-Fang

2018-02-01

In this paper, by solving a complex nonlinear Schrödinger equation, radially symmetric dissipative vortex solitons are obtained analytically and are tested numerically. We find that spatially inhomogeneous nonlinear absorption gives rise to the stability of dissipative vortex solitons in self-defocusing nonlinear medium in the presence of constant linear gain. Numerical simulation reveals the interaction effect among linear gain and nonlinear loss in the azimuthal modulation instabilities of these vortices suppression. Apart from the uniform linear gain indeed affects the stability of vortex in this media, another noticeable feature of current setup is that the steep spatial modulation of the nonlinear absorption can suppress sidelobes effectively and support stable vortex solitons in situations with uniform linear gain. Under appropriate conditions, the vortex solitons can propagate stably and feature no symmetry breaking, although the beams exhibit radical compression and amplification as they propagate. Supported by the National Natural Science Foundation of China under Grant No. 11705164 and the Zhejiang Provincial Natural Science Foundation of China under Grant No. LQ16A040003

Absorption spectrum of DNA for wavelengths greater than 300 nm

International Nuclear Information System (INIS)

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

1981-01-01

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

In vivo analysis of supersaturation/precipitation/absorption behavior after oral administration of pioglitazone hydrochloride salt; determinant site of oral absorption.

Science.gov (United States)

Tanaka, Yusuke; Sugihara, Masahisa; Kawakami, Ayaka; Imai, So; Itou, Takafumi; Murase, Hirokazu; Saiki, Kazunori; Kasaoka, Satoshi; Yoshikawa, Hiroshi

2017-08-30

The purpose of this study was to evaluate in vivo supersaturation/precipitation/absorption behavior in the gastrointestinal (GI) tract based on the luminal concentration-time profiles after oral administration of pioglitazone (PG, a highly permeable lipophilic base) and its hydrochloride salt (PG-HCl) to rats. In the in vitro precipitation experiment in the classic closed system, while the supersaturation was stable in the simulated gastric condition, PG drastically precipitated in the simulated intestinal condition, particularly at a higher initial degree of supersaturation. Nonetheless, a drastic and moderate improvement in absorption was observed in vivo at a low and high dose of PG-HCl, respectively. Analysis based on the luminal concentration of PG after oral administration of PG-HCl at a low dose revealed that most of the dissolved PG emptied from the stomach was rapidly absorbed before its precipitation in the duodenum. At a high dose of PG-HCl, PG partly precipitated in the duodenum but was absorbed to some extent. Therefore, the extent of the absorption was mainly dependent on the duodenal precipitation behavior. Furthermore, a higher-than expected absorption after oral administration of PG-HCl from in vitro precipitation study may be due to the absorption process in the small intestine, which suppresses the precipitation by removal of the drug. This study successfully clarify the impact of the absorption process on the supersaturation/precipitation/absorption behavior and key absorption site for a salt formulation of a highly permeable lipophilic base based on the direct observation of in vivo luminal concentration. Our findings may be beneficial in developing an ideal physiologically based pharmacokinetic model and in vitro predictive dissolution tools and/or translating the in silico and in vitro data to the in vivo outcome. Copyright © 2017 Elsevier B.V. All rights reserved.

OZONE ABSORPTION IN RAW WATERS

Directory of Open Access Journals (Sweden)

LJILJANA TAKIĆ

2008-03-01

Full Text Available The ozone absorption in raw water entering the main ozonization step at the Belgrade drinking water supply plant was investigated in a continuous stirred tank reactor (CSTR. A slow chemical reaction rate of dissolved ozone and pollutants present in raw water have been experimentally determined. The modified Hatta number was defined and calculated as a criterion which determines whether and to which extent the reactions of ozone and pollutants influence the rate of the pure physical ozone absorption.

Laser absorption spectroscopy of oxygen confined in highly porous hollow sphere xerogel.

Science.gov (United States)

Yang, Lin; Somesfalean, Gabriel; He, Sailing

2014-02-10

An Al2O3 xerogel with a distinctive microstructure is studied for the application of laser absorption spectroscopy of oxygen. The xerogel has an exceptionally high porosity (up to 88%) and a large pore size (up to 3.6 µm). Using the method of gas-in-scattering media absorption spectroscopy (GASMAS), a long optical path length (about 3.5m) and high enhancement factor (over 300 times) are achieved as the result of extremely strong multiple-scattering when the light is transmitted through the air-filled, hollow-sphere alumina xerogel. We investigate how the micro-physical feature influences the optical property. As part of the optical sensing system, the material's gas exchange dynamics are also experimentally studied.

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

Science.gov (United States)

Crisp, David; Zuffada, Cinzia

1996-01-01

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

Zinc absorption in inflammatory bowel disease

International Nuclear Information System (INIS)

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

1986-01-01

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

An in silico skin absorption model for fragrance materials.

Science.gov (United States)

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. Copyright © 2014 Elsevier Ltd. All rights reserved.

Acoustic absorption behaviour of an open-celled aluminium foam

International Nuclear Information System (INIS)

Han Fusheng; Seiffert, Gary; Zhao Yuyuan; Gibbs, Barry

2003-01-01

Metal foams, especially close-celled foams, are generally regarded as poor sound absorbers. This paper studies the sound absorption behaviour of the open-celled Al foams manufactured by the infiltration process, and the mechanisms involved. The foams show a significant improvement in sound absorption compared with close-celled Al foams, because of their high flow resistance. The absorption performance can be further enhanced, especially at low frequencies, if the foam panel is backed by an appropriate air gap. Increasing the air-gap depth usually increases both the height and the width of the absorption peak and shifts the peak towards lower frequencies. The foam samples with the smallest pore size exhibit the best absorption capacities when there is no air gap, whereas those with medium pore sizes have the best overall performance when there is an air gap. The typical maximum absorption coefficient, noise reduction coefficient and half-width of the absorption peak are 0.96-0.99, 0.44-0.62 and 1500-3500 Hz, respectively. The sound dissipation mechanisms in the open-celled foams are principally viscous and thermal losses when there is no air-gap backing and predominantly Helmholtz resonant absorption when there is an air-gap backing

The low-ion QSO absorption-line systems

International Nuclear Information System (INIS)

Lanzetta, K.M.

1988-01-01

Various techniques are used to investigate the class of QSO absorption-line systems that exhibit low-ion absorption lines. Four separate investigations are conducted as follows: Spectroscopy of 32 QSOs at red wavelengths is presented and used to investigate intermediate-redshift MgII absorption. A total of 22 Mg II doublets are detected, from which properties of the Mg II absorbers are derived. Marginal evidence for intrinsic evolution of the number density of the Mg II absorbers with redshift is found. The data are combined with previous observations of C IV and C II seen in the same QSOs at blue wavelengths, and the properties of Mg II- and C IV-selected systems are compared. A sample is constructed of 129 QSOs for which are available published data suitable for detecting absorption-line systems that are optically thick to Lyman continuum radiation. A total of 53 such Lyman-limit systems are found, from which properties of the Lyman-limit systems are derived. It is found that the rate of incidence of the systems does not strongly evolved with redshift. This result is contrasted with the evolution found previously for systems selected on the basis of Mg II absorption. Spectroscopy at red wavelengths of eight QSOs with known damped Lyα absorption systems is presented. Spectroscopic and spectrophotometric observations aimed at detecting molecular hydrogen and dust in the z = 2.796 damped Lyα absorber toward Q1337 + 113 are presented

Chemical Absorption Materials

DEFF Research Database (Denmark)

Thomsen, Kaj

2011-01-01

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

Phytosterol glycosides reduce cholesterol absorption in humans.

Science.gov (United States)

Lin, Xiaobo; Ma, Lina; Racette, Susan B; Anderson Spearie, Catherine L; Ostlund, Richard E

2009-04-01

Dietary phytosterols inhibit intestinal cholesterol absorption and regulate whole body cholesterol excretion and balance. However, they are biochemically heterogeneous and a portion is glycosylated in some foods with unknown effects on biological activity. We tested the hypothesis that phytosterol glycosides reduce cholesterol absorption in humans. Phytosterol glycosides were extracted and purified from soy lecithin in a novel two-step process. Cholesterol absorption was measured in a series of three single-meal tests given at intervals of 2 wk to each of 11 healthy subjects. In a randomized crossover design, participants received approximately 300 mg of added phytosterols in the form of phytosterol glycosides or phytosterol esters, or placebo in a test breakfast also containing 30 mg cholesterol-d7. Cholesterol absorption was estimated by mass spectrometry of plasma cholesterol-d7 enrichment 4-5 days after each test. Compared with the placebo test, phytosterol glycosides reduced cholesterol absorption by 37.6+/-4.8% (Pphytosterol esters 30.6+/-3.9% (P=0.0001). These results suggest that natural phytosterol glycosides purified from lecithin are bioactive in humans and should be included in methods of phytosterol analysis and tables of food phytosterol content.

Absorption coefficients of silicon: A theoretical treatment

Science.gov (United States)

Tsai, Chin-Yi

2018-05-01

A theoretical model with explicit formulas for calculating the optical absorption and gain coefficients of silicon is presented. It incorporates direct and indirect interband transitions and considers the effects of occupied/unoccupied carrier states. The indirect interband transition is calculated from the second-order time-independent perturbation theory of quantum mechanics by incorporating all eight possible routes of absorption or emission of photons and phonons. Absorption coefficients of silicon are calculated from these formulas. The agreements and discrepancies among the calculated results, the Rajkanan-Singh-Shewchun (RSS) formula, and Green's data are investigated and discussed. For example, the RSS formula tends to overestimate the contributions of indirect transitions for cases with high photon energy. The results show that the state occupied/unoccupied effect is almost negligible for silicon absorption coefficients up to the onset of the optical gain condition where the energy separation of Quasi-Femi levels between electrons and holes is larger than the band-gap energy. The usefulness of using the physics-based formulas, rather than semi-empirical fitting ones, for absorption coefficients in theoretical studies of photovoltaic devices is also discussed.

Frenkel defect absorption on dislocations and dislocation discharge rate. Modeling determination of the absorption zone

International Nuclear Information System (INIS)

Mikhlin, Eh.Ya.

1988-01-01

A situation connected with the fact that evaluations of dislocation discharge strength which somehow or other are based on the elasticity theory in the dislocation nucleus or near it, do not lead to results complying with experimental data, is discussed. Bases of the alternative approach to this problem consisting in direct investigation into the process of Frenkel defect absorption on dislocation by its computerized simulation at the microscopic level are also presented. Methods of investigation and results are described using α dislocation in iron-alpha as an example. The concept of zones of vacancy and interstitial atom absorption on dislocation is discussed. It is shown that a spontaneous transition, performed by any of these defects near a dislocation is not always identical to absorption and usually appears to be only a part of a multistage process leading to the defect disappearance. Potential relief characteristics for vacancy movement near the dislocation are found. An area wide enough in a transverse direction is found around the dislocation. Vacncies reaching this area can be easily transported to places of their disappearance. Therefore the vacancy entry to this area is equivalent to the absorption. the procedure of simulating the atomic structure of a crystallite containing a dislocation with a step is described. Positions from which these defects perform spontaneous transitions, reaching the disappearance places are found on the dislocation near the step

Far-wing absorption in Na-Ar collision

International Nuclear Information System (INIS)

Kulander, K.C.

1985-01-01

Collision-induced absorption and emission at wavelengths well removed from line center play important roles in many atomic and molecular processes. The authors have developed the theory and computer codes to calculate exact quantum mechanical cross sections for these optical and radiative collisions between atoms. The authors also have produced a quasi-classical model that can efficiently generate accurate absorption cross sections. This model cannot, however, give branching ratios for the final-state populations. Their codes and model can be used to study the propagation of nearly resonant light through gaseous media and to calculate accurate gain and absorption cross sections for the far wings of atomic transitions. The authors have used their theory to study the collision-induced absorption by sodium in argon for wavelengths in the vicinity of the resonance lines D 1 and D 2

Precision atomic beam density characterization by diode laser absorption spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Oxley, Paul; Wihbey, Joseph [Physics Department, The College of the Holy Cross, Worcester, Massachusetts 01610 (United States)

2016-09-15

We provide experimental and theoretical details of a simple technique to determine absolute line-of-sight integrated atomic beam densities based on resonant laser absorption. In our experiments, a thermal lithium beam is chopped on and off while the frequency of a laser crossing the beam at right angles is scanned slowly across the resonance transition. A lock-in amplifier detects the laser absorption signal at the chop frequency from which the atomic density is determined. The accuracy of our experimental method is confirmed using the related technique of wavelength modulation spectroscopy. For beams which absorb of order 1% of the incident laser light, our measurements allow the beam density to be determined to an accuracy better than 5% and with a precision of 3% on a time scale of order 1 s. Fractional absorptions of order 10{sup −5} are detectable on a one-minute time scale when we employ a double laser beam technique which limits laser intensity noise. For a lithium beam with a thickness of 9 mm, we have measured atomic densities as low as 5 × 10{sup 4} atoms cm{sup −3}. The simplicity of our technique and the details we provide should allow our method to be easily implemented in most atomic or molecular beam apparatuses.

Precision atomic beam density characterization by diode laser absorption spectroscopy

International Nuclear Information System (INIS)

Oxley, Paul; Wihbey, Joseph

2016-01-01

We provide experimental and theoretical details of a simple technique to determine absolute line-of-sight integrated atomic beam densities based on resonant laser absorption. In our experiments, a thermal lithium beam is chopped on and off while the frequency of a laser crossing the beam at right angles is scanned slowly across the resonance transition. A lock-in amplifier detects the laser absorption signal at the chop frequency from which the atomic density is determined. The accuracy of our experimental method is confirmed using the related technique of wavelength modulation spectroscopy. For beams which absorb of order 1% of the incident laser light, our measurements allow the beam density to be determined to an accuracy better than 5% and with a precision of 3% on a time scale of order 1 s. Fractional absorptions of order 10 −5 are detectable on a one-minute time scale when we employ a double laser beam technique which limits laser intensity noise. For a lithium beam with a thickness of 9 mm, we have measured atomic densities as low as 5 × 10 4 atoms cm −3 . The simplicity of our technique and the details we provide should allow our method to be easily implemented in most atomic or molecular beam apparatuses.

Precision atomic beam density characterization by diode laser absorption spectroscopy.

Science.gov (United States)

Oxley, Paul; Wihbey, Joseph

2016-09-01

We provide experimental and theoretical details of a simple technique to determine absolute line-of-sight integrated atomic beam densities based on resonant laser absorption. In our experiments, a thermal lithium beam is chopped on and off while the frequency of a laser crossing the beam at right angles is scanned slowly across the resonance transition. A lock-in amplifier detects the laser absorption signal at the chop frequency from which the atomic density is determined. The accuracy of our experimental method is confirmed using the related technique of wavelength modulation spectroscopy. For beams which absorb of order 1% of the incident laser light, our measurements allow the beam density to be determined to an accuracy better than 5% and with a precision of 3% on a time scale of order 1 s. Fractional absorptions of order 10 -5 are detectable on a one-minute time scale when we employ a double laser beam technique which limits laser intensity noise. For a lithium beam with a thickness of 9 mm, we have measured atomic densities as low as 5 × 10 4 atoms cm -3 . The simplicity of our technique and the details we provide should allow our method to be easily implemented in most atomic or molecular beam apparatuses.

Linear absorptive dielectrics

Science.gov (United States)

Tip, A.

1998-06-01

Starting from Maxwell's equations for a linear, nonconducting, absorptive, and dispersive medium, characterized by the constitutive equations D(x,t)=ɛ1(x)E(x,t)+∫t-∞dsχ(x,t-s)E(x,s) and H(x,t)=B(x,t), a unitary time evolution and canonical formalism is obtained. Given the complex, coordinate, and frequency-dependent, electric permeability ɛ(x,ω), no further assumptions are made. The procedure leads to a proper definition of band gaps in the periodic case and a new continuity equation for energy flow. An S-matrix formalism for scattering from lossy objects is presented in full detail. A quantized version of the formalism is derived and applied to the generation of Čerenkov and transition radiation as well as atomic decay. The last case suggests a useful generalization of the density of states to the absorptive situation.

Coherent enhancement of resonance-mediated multiphoton absorption

International Nuclear Information System (INIS)

Zhang, Shian; Zhang, Hui; Jia, Tianqing; Wang, Zugeng; Sun, Zhenrong

2010-01-01

In this paper, we theoretically investigate the coherent enhancement of resonance-mediated (2+2) four-photon absorption. It is found that by shaping the spectral phase with a π phase step, the resonance-mediated (2+2) four-photon transition probability can be enhanced. Furthermore, the coherent enhancement dependences on the detuning between the two two-photon absorptions, laser spectral bandwidth and laser centre frequency are explicitly discussed and analysed. We believe these theoretical results may play an important role in enhancing more complex resonance-mediated multiphoton absorption processes.

The Driving Forces of Subsidiary Absorptive Capacity

DEFF Research Database (Denmark)

Schleimer, Stephanie C.; Pedersen, Torben

2013-01-01

The study investigates how a multinational corporation (MNC) can promote the absorptive capacity of its subsidiaries. The focus is on what drives the MNC subsidiary's ability to absorb marketing strategies that are initiated by the MNC parent, as well as how the subsidiary enacts on this absorptive...... as a purposeful response to this dual embeddedness. An analysis of marketing strategy absorptions undertaken by 213 subsidiaries reveals that MNCs can assist their subsidiaries to compete in competitive and dynamic focal markets by forming specific organizational mechanisms that are conducive to the development...

Absorption and scattering of laser radiation by the diffusion flame of aviation kerosene

Energy Technology Data Exchange (ETDEWEB)

Gvozdev, S V; Glova, A F; Dubrovskii, V Yu; Durmanov, S T; Krasyukov, A G; Lysikov, A Yu; Smirnov, G V; Solomakhin, V B

2012-04-30

The absorption coefficient of the radiation of a repetitively pulsed Nd : YAG laser with an average output power up to 6 W and of a cw ytterbium optical fibre laser with an output power up to 3 kW was measured in the diffusion flame of aviation kerosene burning on a free surface in the atmospheric air. The absorption coefficient as a function of flame length, radiation power, and radiation intensity, which was varied in the {approx}10{sup 3} - 5 Multiplication-Sign 10{sup 4} W cm{sup -2} range, was obtained for two distances (1 and 2 cm) between the laser beam axis and the surface. The coefficient of radiation absorption by kerosene flame was compared with that in ethanol and kerosene - ethanol mixture flames. The radiation power scattered by a small segment of the kerosene flame irradiated by Nd : YAG laser radiation was measured as a function of longitudinal and azimuthal coordinates. An estimate was made of the total scattered radiation power.

Absorption and scattering of laser radiation by the diffusion flame of aviation kerosene

International Nuclear Information System (INIS)

Gvozdev, S V; Glova, A F; Dubrovskii, V Yu; Durmanov, S T; Krasyukov, A G; Lysikov, A Yu; Smirnov, G V; Solomakhin, V B

2012-01-01

The absorption coefficient of the radiation of a repetitively pulsed Nd : YAG laser with an average output power up to 6 W and of a cw ytterbium optical fibre laser with an output power up to 3 kW was measured in the diffusion flame of aviation kerosene burning on a free surface in the atmospheric air. The absorption coefficient as a function of flame length, radiation power, and radiation intensity, which was varied in the ∼10 3 - 5×10 4 W cm -2 range, was obtained for two distances (1 and 2 cm) between the laser beam axis and the surface. The coefficient of radiation absorption by kerosene flame was compared with that in ethanol and kerosene - ethanol mixture flames. The radiation power scattered by a small segment of the kerosene flame irradiated by Nd : YAG laser radiation was measured as a function of longitudinal and azimuthal coordinates. An estimate was made of the total scattered radiation power.

Absorption and scattering of laser radiation by the diffusion flame of aviation kerosene

Science.gov (United States)

Gvozdev, S. V.; Glova, A. F.; Dubrovskii, V. Yu; Durmanov, S. T.; Krasyukov, A. G.; Lysikov, A. Yu; Smirnov, G. V.; Solomakhin, V. B.

2012-04-01

The absorption coefficient of the radiation of a repetitively pulsed Nd : YAG laser with an average output power up to 6 W and of a cw ytterbium optical fibre laser with an output power up to 3 kW was measured in the diffusion flame of aviation kerosene burning on a free surface in the atmospheric air. The absorption coefficient as a function of flame length, radiation power, and radiation intensity, which was varied in the ~103 — 5×104 W cm-2 range, was obtained for two distances (1 and 2 cm) between the laser beam axis and the surface. The coefficient of radiation absorption by kerosene flame was compared with that in ethanol and kerosene — ethanol mixture flames. The radiation power scattered by a small segment of the kerosene flame irradiated by Nd : YAG laser radiation was measured as a function of longitudinal and azimuthal coordinates. An estimate was made of the total scattered radiation power.

Analytic descriptions of ion cyclotron absorption

International Nuclear Information System (INIS)

Bers, A.; Francis, G.; Fuchs, V.; Lashmore-Davies, C.N.; Ram, A.K.

1987-05-01

Analysis of energy propagation and absorption in ion-cyclotron heating of tokamak plasmas has relied on numerical solutions of fourth (and sixth) order differential equations for slab models of the plasma (poloidal) cross section. Realistic two-dimensional and fully toroidal geometry analyses would become quite unwieldy. It is shown here that the analysis of the slab model can be simplified considerably. A first-order differential equation is shown to describe the transmission coefficient for the fast wave, and it is solved analytically. A second order differential equation is shown to adequately describe both transmission and reflection. Conditions for ion absorption or mode conversion are derived. Including toroidal effects in propagation, conditions for electron absorption on the mode-converted ion-Bernstein waves are also described analytically

Absorption spectra of AA-stacked graphite

International Nuclear Information System (INIS)

Chiu, C W; Lee, S H; Chen, S C; Lin, M F; Shyu, F L

2010-01-01

AA-stacked graphite shows strong anisotropy in geometric structures and velocity matrix elements. However, the absorption spectra are isotropic for the polarization vector on the graphene plane. The spectra exhibit one prominent plateau at middle energy and one shoulder structure at lower energy. These structures directly reflect the unique geometric and band structures and provide sufficient information for experimental fitting of the intralayer and interlayer atomic interactions. On the other hand, monolayer graphene shows a sharp absorption peak but no shoulder structure; AA-stacked bilayer graphene has two absorption peaks at middle energy and abruptly vanishes at lower energy. Furthermore, the isotropic features are expected to exist in other graphene-related systems. The calculated results and the predicted atomic interactions could be verified by optical measurements.

Development of absorption fiber optic sensor for distributed measurement of ammonia gas

Science.gov (United States)

Aubrecht, J.; Kalvoda, L.

2013-05-01

Polymer-clad silica optical fibers are employed for development of different absorption optic fiber sensors of gaseous analytes. In our case, the physical principles of the detection are combined with a chemical reaction between analyte and suitable opto-chemical absorption reagents. Selected organometallic complex reagents with different lengths of lateral aliphatic chains are studied with respect to the type of central ions and their coordinative conditions to surrounding ligands. The effect of solvent type on solubility and the long-term stability of the prepared reagents in solid matrix are presented and discussed. Various methods are also tested in order to achieve an effective reagent immobilization into the polymer matrix, which creates optical fiber cladding. The chemical reaction of the reagents with ammonia based on ligand exchange process is accompanied by changes of visible-near-infrared optical absorption influencing via evanescent field on the guided light intensity. Experimental results suggest that the selected reagents provide optical properties suitable for practical sensing applications and that the sensitized PCS optical fibers could be used for detection of ammonia gas.

Collision-Induced Infrared Absorption by Molecular Hydrogen Pairs at Thousands of Kelvin

Directory of Open Access Journals (Sweden)

Xiaoping Li

2010-01-01

Full Text Available Collision-induced absorption by hydrogen and helium in the stellar atmospheres of cool white dwarfs causes the emission spectra to differ significantly from the expected blackbody spectra of the cores. For detailed modeling of radiative processes at temperatures up to 7000 K, the existing H2–H2 induced dipole and potential energy surfaces of high quality must be supplemented by calculations with the H2 bonds stretched or compressed far from the equilibrium length. In this work, we describe new dipole and energy surfaces, based on more than 20 000 ab initio calculations for H2–H2. Our results agree well with previous ab initio work (where those data exist; the calculated rototranslational absorption spectrum at 297.5 K matches experiment similarly well. We further report the calculated absorption spectra of H2–H2 for frequencies from the far infrared to 20 000 cm−1, at temperatures of 600 K, 1000 K, and 2000 K, for which there are no experimental data.

Extended x-ray absorption fine structure studies of amorphous and crystalline Si-Ge alloys with synchrotron radiation

International Nuclear Information System (INIS)

Kajiyama, Hiroshi

1988-01-01

Extended X-ray absorption fine structure (EXAFS) is a powerful probe to study the local structure around the atom of a specific element. In conventional EXAFS analysis, it has been known that reliable structures are obtained with the different values of absorption edge energy for different neighboring atoms. It is shown in this study that the Ge-K edge EXAFS resulting from the Ge-Ge and Ge-Si bonds in hydrogenated amorphous Si-Ge alloys was able to be excellently explained by a unique absorption edge energy value, provided that a newly developed formula based on the spherical wave function of photoelectrons is used. The microscopic structures of hydrogenated amorphous Si-Ge alloys and crystalline Si-Ge alloys have been determined using the EXAFS method. The lengths of Ge-Ge and Ge-Si bonds were constant throughout their entire composition range, and it was found that the length of Ge-Si bond was close to the average value of the bond lengths of both Ge and Si crystals. In crystalline Si-Ge alloys, it has been shown that the bonds relaxed completely, while the lattice constant varied monotonously with the composition. (Kako, I.)

Discovery of an X-ray Violently Variable Broad Absorption Line Quasar

Science.gov (United States)

Ghosh, Kajal K.; Gutierrez, Carlos M.; Punsly, Brian; Chevallier, Loic; Goncalves, Anabela C.

2006-01-01

In this letter, we report on a quasar that is violently variable in the X-rays, XVV. It is also a broad absorption line quasar (BALQSO) that exhibits both high ionization and low ionization UV absorption lines (LoBALQSO). It is very luminous in the X-rays (approximately 10(exp 46) ergs s(sup -l) over the entire X-ray band). Surprisingly, this does not over ionize the LoBAL outflow. The X-rays vary by a factor of two within minutes in the quasar rest frame, which is shorter than 1/30 of the light travel time across a scale length equal to the black hole radius. We concluded that the X-rays are produced in a relativistic jet beamed toward earth in which variations in the Doppler enhancement produce the XVV behavior.

Approaching Resonant Absorption of Environmental Xenobiotics Harmonic Oscillation by Linear Structures

Directory of Open Access Journals (Sweden)

Cornelia A. Bulucea

2012-03-01

Full Text Available Over the last several decades, it has become increasingly accepted that the term xenobiotic relates to environmental impact, since environmental xenobiotics are understood to be substances foreign to a biological system, which did not exist in nature before their synthesis by humans. In this context, xenobiotics are persistent pollutants such as dioxins and polychlorinated biphenyls, as well as plastics and pesticides. Dangerous and unstable situations can result from the presence of environmental xenobiotics since their harmful effects on humans and ecosystems are often unpredictable. For instance, the immune system is extremely vulnerable and sensitive to modulation by environmental xenobitics. Various experimental assays could be performed to ascertain the immunotoxic potential of environmental xenobiotics, taking into account genetic factors, the route of xenobiotic penetration, and the amount and duration of exposure, as well as the wave shape of the xenobiotic. In this paper, we propose an approach for the analysis of xenobiotic metabolism using mathematical models and corresponding methods. This study focuses on a pattern depicting mathematically modeled processes of resonant absorption of a xenobiotic harmonic oscillation by an organism modulated as an absorbing oscillator structure. We represent the xenobiotic concentration degree through a spatial concentration vector, and we model and simulate the oscillating regime of environmental xenobiotic absorption. It is anticipated that the results could be used to facilitate the assessment of the processes of environmental xenobiotic absorption, distribution, biotransformation and removal within the framework of compartmental analysis, by establishing appropriate mathematical models and simulations.

Calcium absorption from fortified ice cream formulations compared with calcium absorption from milk.

Science.gov (United States)

van der Hee, Regine M; Miret, Silvia; Slettenaar, Marieke; Duchateau, Guus S M J E; Rietveld, Anton G; Wilkinson, Joy E; Quail, Patricia J; Berry, Mark J; Dainty, Jack R; Teucher, Birgit; Fairweather-Tait, Susan J

2009-05-01

Optimal bone mass in early adulthood is achieved through appropriate diet and lifestyle, thereby protecting against osteoporosis and risk of bone fracture in later life. Calcium and vitamin D are essential to build adequate bones, but calcium intakes of many population groups do not meet dietary reference values. In addition, changes in dietary patterns are exacerbating the problem, thereby emphasizing the important role of calcium-rich food products. We have designed a calcium-fortified ice cream formulation that is lower in fat than regular ice cream and could provide a useful source of additional dietary calcium. Calcium absorption from two different ice cream formulations was determined in young adults and compared with milk. Sixteen healthy volunteers (25 to 45 years of age), recruited from the general public of The Netherlands, participated in a randomized, reference-controlled, double-blind cross-over study in which two test products and milk were consumed with a light standard breakfast on three separate occasions: a standard portion of ice cream (60 g) fortified with milk minerals and containing a low level (3%) of butter fat, ice cream (60 g) fortified with milk minerals and containing a typical level (9%) of coconut oil, and reduced-fat milk (1.7% milk fat) (200 mL). Calcium absorption was measured by the dual-label stable isotope technique. Effects on calcium absorption were evaluated by analysis of variance. Fractional absorption of calcium from the 3% butterfat ice cream, 9% coconut oil ice cream, and milk was 26%+/-8%, 28%+/-5%, and 31%+/-9%, respectively, and did not differ significantly (P=0.159). Results indicate that calcium bioavailability in the two calcium-fortified ice cream formulations used in this study is as high as milk, indicating that ice cream may be a good vehicle for delivery of calcium.

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

Science.gov (United States)

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

2003-04-01

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

Systematic review: Helicobacter pylori infection and impaired drug absorption.

Science.gov (United States)

Lahner, E; Annibale, B; Delle Fave, G

2009-02-15

Impaired acid secretion may affect drug absorption and may be consequent to corporal Helicobacter pylori-gastritis, which may affect the absorption of orally administered drugs. To focus on the evidence of impaired drug absorption associated with H. pylori infection. Data sources were the systematic search of MEDLINE/EMBASE/SCOPUS databases (1980-April 2008) for English articles using the keywords: drug malabsorption/absorption, stomach, Helicobacter pylori, gastritis, gastric acid, gastric pH, hypochlorhydria, gastric hypoacidity. Study selection was made from 2099 retrieved articles, five studies were identified. Data were extracted from selected papers, investigated drugs, study type, main features of subjects, study design, intervention type and results were extracted. In all, five studies investigated impaired absorption of l-dopa, thyroxine and delavirdine in H. pylori infection. Eradication treatment led to 21-54% increase in l-dopa in Parkinson's disease. Thyroxine requirement was higher in hypochlorhydric goitre with H. pylori-gastritis and thyrotropin levels decreased by 94% after treatment. In H. pylori- and HIV-positive hypochlorhydric subjects, delavirdine absorption increased by 57% with orange juice administration and by 150% after eradication. A plausible mechanism of impaired drug absorption is decreased acid secretion in H. pylori-gastritis patients. Helicobacter pylori infection and hypochlorhydria should be considered in prescribing drugs the absorption of which is potentially affected by intragastric pH.

Grazing exit versus grazing incidence geometry for x-ray absorption near edge structure analysis of arsenic traces

International Nuclear Information System (INIS)

Meirer, F.; Streli, C.; Wobrauschek, P.; Zoeger, N.; Pepponi, G.

2009-01-01

In the presented study the grazing exit x-ray fluorescence was tested for its applicability to x-ray absorption near edge structure analysis of arsenic in droplet samples. The experimental results have been compared to the findings of former analyses of the same samples using a grazing incidence (GI) setup to compare the performance of both geometries. Furthermore, the investigations were accomplished to gain a better understanding of the so called self-absorption effect, which was observed and investigated in previous studies using a GI geometry. It was suggested that a normal incidence-grazing-exit geometry would not suffer from self-absorption effects in x-ray absorption fine structure (XAFS) analysis due to the minimized path length of the incident beam through the sample. The results proved this assumption and in turn confirmed the occurrence of the self-absorption effect for GI geometry. Due to its lower sensitivity it is difficult to apply the GE geometry to XAFS analysis of trace amounts (few nanograms) of samples but the technique is well suited for the analysis of small amounts of concentrated samples

Impact of Tidal Level Variations on Wave Energy Absorption at Wave Hub

Directory of Open Access Journals (Sweden)

Valeria Castellucci

2016-10-01

Full Text Available The energy absorption of the wave energy converters (WEC characterized by a limited stroke length —like the point absorbers developed at Uppsala University—depends on the sea level variation at the deployment site. In coastal areas characterized by high tidal ranges, the daily energy production of the generators is not optimal. The study presented in this paper quantifies the effects of the changing sea level at the Wave Hub test site, located at the south-west coast of England. This area is strongly affected by tides: the tidal height calculated as the difference between the Mean High Water Spring and the Mean Low Water Spring in 2014 was about 6.6 m. The results are obtained from a hydro-mechanic model that analyzes the behaviour of the point absorber at the Wave Hub, taking into account the sea state occurrence scatter diagram and the tidal time series at the site. It turns out that the impact of the tide decreases the energy absorption by 53%. For this reason, the need for a tidal compensation system to be included in the design of the WEC becomes compelling. The economic advantages are evaluated for different scenarios: the economic analysis proposed within the paper allows an educated guess to be made on the profits. The alternative of extending the stroke length of the WEC is investigated, and the gain in energy absorption is estimated.

Wine absorption by cork stoppers research in foods

Energy Technology Data Exchange (ETDEWEB)

Gonzalez-Adrados, J. R.; Gonzalez-Hernandez, F.; Garcia de Ceca, J. L.; Caceres-Esteban, M. J.; Garcia-Vallejo, M. C.

2008-07-01

To evaluate the magnitude of wine absorption by cork under conditions as close to reality as possible and its evolution in time, ready-to-use natural cork stoppers and ''1+1'' cork stoppers were used to close bottles filled with red wine. Stoppers were removed after 3, 6, 12 and 24 months of contact to determine absorption of liquid and liquid progression along the lateral surface of the cork stopper.Variation of absorption with contact time was studied by adjusting the model Absorption = a {radical} t(R{sup 2}: 82.19 - 93.63%). A scheme of the evolution of wine absorption with time is proposed, differentiating liquid flow along cork-glass interface, diffusion in cell walls and liquid flow through the cell lumens. In conditions of use, a value of 4.48.10{sup 1}3 m{sup 2} s{sup -}1 was obtained for non-radial diffusion coefficient (D). (Author) 13 refs.

Exercise, Insulin Absorption Rates, and Artificial Pancreas Control

Science.gov (United States)

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.

Broadband perfect infrared absorption by tuning epsilon-near-zero and epsilon-near-pole resonances of multilayer ITO nanowires.

Science.gov (United States)

Zhou, Kun; Cheng, Qiang; Song, Jinlin; Lu, Lu; Jia, Zhihao; Li, Junwei

2018-01-01

We numerically investigate the broadband perfect infrared absorption by tuning epsilon-near-zero (ENZ) and epsilon-near-pole (ENP) resonances of multilayer indium tin oxide nanowires (ITO NWs). The monolayer ITO NWs array shows intensive absorption at ENZ and ENP wavelengths for p polarization, while only at the ENP wavelength for s polarization. Moreover, the ENP resonances are almost omnidirectional and the ENZ resonances are angularly dependent. Therefore, the absorption bandwidth is broader for p polarization than that for s polarization when polarized waves are incident obliquely. The ENZ resonances can be tuned by altering the doping concentration and volume filling factor of ITO NWs. However, the ENP resonances only can be tuned by changing the doping concentration of ITO NWs, and volume filling factor impacts little on the ENP resonances. Based on the strong absorption properties of each layer at their own ENP and ENZ resonances, the tuned absorption of the bilayer ITO NWs with the different doping concentrations can be broader and stronger. Furthermore, multilayer ITO NWs can achieve broadband perfect absorption by controlling the doping concentration, volume filling factor, and length of the NWs in each layer. This study has the potential to apply to applications requiring efficient absorption and energy conversion.

Absorption of medicamental iron and iron from food

International Nuclear Information System (INIS)

Reizenstein, P.; Carlmark, B.; Ehn, L.; Forsberg, K.; Hoeglund, S.; Terpstra, T.

1976-01-01

Methods are reviewed for the measurement of iron absorption. The chemical balance method has been almost entirely supplanted by radioisotope methods, which include notably whole-body counting and measurement of incorporation of radioiron into red cells. A survey is also given of the various conditions that influence iron absorption, including chemical form of iron, amount of iron, accompanying diet. Absorption tests must be conducted under relevant conditions. (author)

Acoustic absorption of natural gas compression facility enclosures

Energy Technology Data Exchange (ETDEWEB)

Lassen, P.; Wong, G. [Noise Management Ltd., Calgary, AB (Canada)

2009-07-01

Noise sources at gas compressor facilities include the enclosure/building housing a gas engine and compressor, the ventilation openings, doors and windows for the enclosure, the engine air intake and exhaust, and a cooler. Accurate predictions of the noise levels inside the enclosure, the breakout noise from open windows and doors and ventilation, as well as the transmission through the walls, is necessary in order to determine cost effective noise mitigation for the facility. In order to accurately predict the sound breakout from these facilities it is necessary to know the acoustic absorption of the interior of these equipment enclosures. Although the acoustic absorption data of the wall systems may be available, the absorption attributable to the non-enclosure surfaces, the equipment and fittings, is not usually known and is difficult to predict. Since piping, instrumentation and mechanical equipment often take on a typical arrangement, shape, volumetric density and material composition, it is useful to know the typical acoustic absorption attributable to these items. In this study, reverberation time (RT) measurements were taken at 2 decommissioned gas compressor facilities in order to determine the absorption characteristics of the enclosure. The RT was measured according to ASTM C423-02a. The overall absorption coefficient of a compressor enclosure with a solid liner was found to be similar to that of steel decking. Fittings within the enclosure did not increase the high frequency absorption of the enclosure. It was concluded that room modes, structural vibrations, and fittings may serve to increase the effective absorption at frequencies below 630 Hz. Because of the small dimensions of the enclosure, low-frequency response of the room affected the reliability of the data below 160Hz. Structural vibration of the enclosure was investigated, and may considerably influence the noise breakout from the enclosure apart from the interior acoustical considerations. 4

Acoustic absorption of natural gas compression facility enclosures

International Nuclear Information System (INIS)

Lassen, P.; Wong, G.

2009-01-01

Noise sources at gas compressor facilities include the enclosure/building housing a gas engine and compressor, the ventilation openings, doors and windows for the enclosure, the engine air intake and exhaust, and a cooler. Accurate predictions of the noise levels inside the enclosure, the breakout noise from open windows and doors and ventilation, as well as the transmission through the walls, is necessary in order to determine cost effective noise mitigation for the facility. In order to accurately predict the sound breakout from these facilities it is necessary to know the acoustic absorption of the interior of these equipment enclosures. Although the acoustic absorption data of the wall systems may be available, the absorption attributable to the non-enclosure surfaces, the equipment and fittings, is not usually known and is difficult to predict. Since piping, instrumentation and mechanical equipment often take on a typical arrangement, shape, volumetric density and material composition, it is useful to know the typical acoustic absorption attributable to these items. In this study, reverberation time (RT) measurements were taken at 2 decommissioned gas compressor facilities in order to determine the absorption characteristics of the enclosure. The RT was measured according to ASTM C423-02a. The overall absorption coefficient of a compressor enclosure with a solid liner was found to be similar to that of steel decking. Fittings within the enclosure did not increase the high frequency absorption of the enclosure. It was concluded that room modes, structural vibrations, and fittings may serve to increase the effective absorption at frequencies below 630 Hz. Because of the small dimensions of the enclosure, low-frequency response of the room affected the reliability of the data below 160Hz. Structural vibration of the enclosure was investigated, and may considerably influence the noise breakout from the enclosure apart from the interior acoustical considerations. 4

Electroabsorption optical modulator

Energy Technology Data Exchange (ETDEWEB)

Skogen, Erik J.

2017-11-21

An electroabsorption modulator incorporates waveguiding regions along the length of the modulator that include quantum wells where at least two of the regions have quantum wells with different bandgaps. In one embodiment of the invention, the regions are arranged such that the quantum wells have bandgaps with decreasing bandgap energy along the length of the modulator from the modulator's input to its output. The bandgap energy of the quantum wells may be decreased in discrete steps or continuously. Advantageously, such an arrangement better distributes the optical absorption as well as the carrier density along the length of the modulator. Further advantageously, the modulator may handle increased optical power as compared with prior art modulators of similar dimensions, which allows for improved link gain when the optical modulator is used in an analog optical communication link.

Photoelectric absorption cross sections with variable abundances

Science.gov (United States)

Balucinska-Church, Monika; Mccammon, Dan

1992-01-01

Polynomial fit coefficients have been obtained for the energy dependences of the photoelectric absorption cross sections of 17 astrophysically important elements. These results allow the calculation of X-ray absorption in the energy range 0.03-10 keV in material with noncosmic abundances.

Alkali absorption and citrate excretion in calcium nephrolithiasis

Science.gov (United States)

Sakhaee, K.; Williams, R. H.; Oh, M. S.; Padalino, P.; Adams-Huet, B.; Whitson, P.; Pak, C. Y.

1993-01-01

The role of net gastrointestinal (GI) alkali absorption in the development of hypocitraturia was investigated. The net GI absorption of alkali was estimated from the difference between simple urinary cations (Ca, Mg, Na, and K) and anions (Cl and P). In 131 normal subjects, the 24 h urinary citrate was positively correlated with the net GI absorption of alkali (r = 0.49, p origin of hypocitraturia. However, the normal dependence was maintained in CDS and in idiopathic hypocitraturia, suggesting that reduced citrate excretion was largely dietary in origin as a result of low net alkali absorption (from a probable relative deficiency of vegetables and fruits or a relative excess of animal proteins).

Absorption technology for solar and waste heat utilization

International Nuclear Information System (INIS)

Grossman, G.

1993-01-01

Absorption heat pumps, first developed in the 19th century, have received renewed and growing attention in the past two decades. With the increasing cost of oil and electricity, the particular features of this heat-powered cycle have made it attractive for both residential and industrial applications. Solar-powered air conditioning, gas-fired domestic cooling and waste-heat-powered temperature boosters are some of the applications on which intensive research and development has been conducted. This paper describes the operation of absorption systems and discusses several practical applications. It surveys recent advances in absorption technology, including the selection of working fluids, cycle improvements and multi-staging, and fundamentals of the combined heat and mass transfer in absorption processes. (author)

Theory of X-ray absorption and emission spectra

International Nuclear Information System (INIS)

Mukoyama, Takeshi

2004-01-01

Theoretical studies on X-ray absorption and emission spectroscopy are discussed. Simple expressions for X-ray emission rate and X-ray absorption cross section are presented in the dipole approximation. Various atomic models to obtain realistic wave functions and theoretical calculations for X-ray absorption cross sections and X-ray emission rates are described. In the case of molecules and solids, molecular orbital methods for electronic structures and molecular wave functions are discussed. The emphasis is on the procedures to obtain the excited-state and continuum wave functions for molecules and to calculate the multi-center dipole matrix elements. The examples of the calculated X-ray absorption and emission spectra are shown and compared with the experimental results

Absorption of femtosecond laser pulses by atomic clusters

International Nuclear Information System (INIS)

Lin Jingquan; Zhang Jie; Li Yingjun; Chen Liming; Lu Tiezheng; Teng Hao

2001-01-01

Energy absorption by Xe, Ar, He atomic clusters are investigated using laser pulses with 5 mJ energy in 150 fs duration. Experimental results show that the size of cluster and laser absorption efficiency are strongly dependent on several factors, such as the working pressure of pulse valve, atomic number Z of the gas. Absorption fraction of Xe clusters is as high as 45% at a laser intensity of 1 x 10 15 W/cm 2 with 20 x 10 5 Pa gas jet backing pressure. Absorption of the atomic clusters is greatly reduced by introducing pre-pulses. Ion energy measurements confirm that the efficient energy deposition results in a plasma with very high ion temperature

Tunable Diode Laser Atomic Absorption Spectroscopy for Detection of Potassium under Optically Thick Conditions.

Science.gov (United States)

Qu, Zhechao; Steinvall, Erik; Ghorbani, Ramin; Schmidt, Florian M

2016-04-05

Potassium (K) is an important element related to ash and fine-particle formation in biomass combustion processes. In situ measurements of gaseous atomic potassium, K(g), using robust optical absorption techniques can provide valuable insight into the K chemistry. However, for typical parts per billion K(g) concentrations in biomass flames and reactor gases, the product of atomic line strength and absorption path length can give rise to such high absorbance that the sample becomes opaque around the transition line center. We present a tunable diode laser atomic absorption spectroscopy (TDLAAS) methodology that enables accurate, calibration-free species quantification even under optically thick conditions, given that Beer-Lambert's law is valid. Analyte concentration and collisional line shape broadening are simultaneously determined by a least-squares fit of simulated to measured absorption profiles. Method validation measurements of K(g) concentrations in saturated potassium hydroxide vapor in the temperature range 950-1200 K showed excellent agreement with equilibrium calculations, and a dynamic range from 40 pptv cm to 40 ppmv cm. The applicability of the compact TDLAAS sensor is demonstrated by real-time detection of K(g) concentrations close to biomass pellets during atmospheric combustion in a laboratory reactor.

The effect of refractive index changes in an intracavity absorption on the laser output power

International Nuclear Information System (INIS)

Al-Hawat, Sh.; Eskef, M.

2007-10-01

A model describing the intra-cavity absorption has been developed. The model allows for a reliable description of the attenuation of laser power as a function of the gas pressure inside the absorption cell, conducting both real and imaginary parts of the refractive index of the absorbing gas. The model relies on an adequate integration of the additional loss due to the absorption into the rate equations. After that the rate equations are solved under steady state conditions, which is quite reliable for a cw CO 2 laser. The oscillation, clearly observed in case of weak absorption, is described in the framework of an interference model considering the electric field inside the cavity as the interference result of successive phase correlated waves differing from each other in the number of passes made through the cavity. The phase shift is determined by the optical length of the cavity depending on the real part of the refractive index of the gas in the absorption cell. The model has been applied to analyze a large set of attenuation curves obtained in a previous work, in which intra-cavity absorption was measured for the three gases CFC-11, 12, 22 using a tunable cw CO 2 laser at 44 lines of the emission spectrum of the CO 2 molecule distributed on the branches P and R of the two bands at 9.6 μm and 10.6 μm. For mostly all examples, the value of the absorption cross section (imaginary part of the refractive index) has been determined by fitting the model to the experimental data. Furthermore, the value of the linear polarizability (real part of the refractive index) has been calculated from the oscillation period for all examples, in which the attenuation curve exhibits reliable oscillating behavior. The results are in fair agreement with the values of the absorption cross section published in the Hitran data base, as well as with the results obtained from independent absorption measurements performed outside the cavity (Author)

Identifying the perfect absorption of metamaterial absorbers

Science.gov (United States)

Duan, G.; Schalch, J.; Zhao, X.; Zhang, J.; Averitt, R. D.; Zhang, X.

2018-01-01

We present a detailed analysis of the conditions that result in unity absorption in metamaterial absorbers to guide the design and optimization of this important class of functional electromagnetic composites. Multilayer absorbers consisting of a metamaterial layer, dielectric spacer, and ground plane are specifically considered. Using interference theory, the dielectric spacer thickness and resonant frequency for unity absorption can be numerically determined from the functional dependence of the relative phase shift of the total reflection. Further, using transmission line theory in combination with interference theory we obtain analytical expressions for the unity absorption resonance frequency and corresponding spacer layer thickness in terms of the bare resonant frequency of the metamaterial layer and metallic and dielectric losses within the absorber structure. These simple expressions reveal a redshift of the unity absorption frequency with increasing loss that, in turn, necessitates an increase in the thickness of the dielectric spacer. The results of our analysis are experimentally confirmed by performing reflection-based terahertz time-domain spectroscopy on fabricated absorber structures covering a range of dielectric spacer thicknesses with careful control of the loss accomplished through water absorption in a semiporous polyimide dielectric spacer. Our findings can be widely applied to guide the design and optimization of the metamaterial absorbers and sensors.

Heavy nucleus resonance absorption in heterogeneous lattices

International Nuclear Information System (INIS)

Coste, M.; Tellier, H.; Brienne-Raepsaet, C.; Van Der Gucht, C.

1992-01-01

To compute easily the neutron reaction rates in the resonance energy range, the reactor physicists use the self-shielding formalism and the effective cross-section concept. Usually, for these calculations, and equivalence process is used, in such a way that the absorption rate is correctly computed for the whole fuel pin. This procedure does not allow to preserve the spatial absorption rate distribution inside the pin. It is an important handicap if we want to reproduce the plutonium distribution in a spent fuel. To avoid this inconvenience, new improvements of the self-shielding formalism have been recently introduced in the new assembly calculation code of the French Atomic Energy Commission, APOLLO 2. With this improved formalism, it is now possible to represent the spatial and energetic dependence of the heavy nucleus absorption inside the fuel pin and to use a fine energy dependent equivalence process. As it does not exist clean experimental results for the spatial and energetic dependence of the absorption, the authors used reference calculations to qualify the self-shielding formalism. For the strongly self-shielded nuclei of interest in reactor physics, U238, Pu240 and Th232, the agreement between the self-shielding calculation and the reference ones is fairly good for the spatial and energetic dependence of the absorption rate

Absorption dynamics and delay time in complex potentials

Science.gov (United States)

Villavicencio, Jorge; Romo, Roberto; Hernández-Maldonado, Alberto

2018-05-01

The dynamics of absorption is analyzed by using an exactly solvable model that deals with an analytical solution to Schrödinger’s equation for cutoff initial plane waves incident on a complex absorbing potential. A dynamical absorption coefficient which allows us to explore the dynamical loss of particles from the transient to the stationary regime is derived. We find that the absorption process is characterized by the emission of a series of damped periodic pulses in time domain, associated with damped Rabi-type oscillations with a characteristic frequency, ω = (E + ε)/ℏ, where E is the energy of the incident waves and ‑ε is energy of the quasidiscrete state of the system induced by the absorptive part of the Hamiltonian; the width γ of this resonance governs the amplitude of the pulses. The resemblance of the time-dependent absorption coefficient with a real decay process is discussed, in particular the transition from exponential to nonexponential regimes, a well-known feature of quantum decay. We have also analyzed the effect of the absorptive part of the potential on the dynamical delay time, which behaves differently from the one observed in attractive real delta potentials, exhibiting two regimes: time advance and time delay.

Energy Absorption in Chopped Carbon Fiber Compression Molded Composites

International Nuclear Information System (INIS)

Starbuck, J.M.

2001-01-01

In passenger vehicles the ability to absorb energy due to impact and be survivable for the occupant is called the ''crashworthiness'' of the structure. To identify and quantify the energy absorbing mechanisms in candidate automotive composite materials, test methodologies were developed for conducting progressive crush tests on composite plate specimens. The test method development and experimental set-up focused on isolating the damage modes associated with the frond formation that occurs in dynamic testing of composite tubes. Quasi-static progressive crush tests were performed on composite plates manufactured from chopped carbon fiber with an epoxy resin system using compression molding techniques. The carbon fiber was Toray T700 and the epoxy resin was YLA RS-35. The effect of various material and test parameters on energy absorption was evaluated by varying the following parameters during testing: fiber volume fraction, fiber length, fiber tow size, specimen width, profile radius, and profile constraint condition. It was demonstrated during testing that the use of a roller constraint directed the crushing process and the load deflection curves were similar to progressive crushing of tubes. Of all the parameters evaluated, the fiber length appeared to be the most critical material parameter, with shorter fibers having a higher specific energy absorption than longer fibers. The combination of material parameters that yielded the highest energy absorbing material was identified

Hybrid Membrane/Absorption Process for Post-combustion CO2 Capture

Energy Technology Data Exchange (ETDEWEB)

Li, Shiguang; Shou, S.; Pyrzynski, Travis; Makkuni, Ajay; Meyer, Howard

2013-12-31

% CO2 product purity was achieved throughout the test. Membrane contactor modules have been scaled from bench scale 2-inch diameter by 12-inch long (20 ft2 membrane surface area) modules to 4-inch diameter by 60-inch long pilot scale modules (165 ft2 membrane surface area). Pilot scale modules were tested in an integrated absorption/regeneration system for CO2 capture field tests at a coal-fired power plant (Midwest Generation’s Will County Station located in Romeoville, IL). Absorption and regeneration contactors were constructed utilizing high performance super-hydrophobic, nano-porous PEEK membranes with CO2 gas permeance of 2,000 GPU and a 1,000 GPU, respectively. Field tests using aMDEA solvent achieved greater than 90% CO2 removal in a single stage. The absorption mass transfer coefficient was 1.2 (sec)-1, exceeding the initial target of 1.0 (sec)-1. This mass transfer coefficient is over one order of magnitude greater than that of conventional gas/liquid contacting equipment. The economic evaluation based on field tests data indicates that the CO2 capture cost associated with membrane contactor technology is $54.69 (Yr 2011$)/tonne of CO2 captured when using aMDEA as a solvent. It is projected that the DOE’s 2025 cost goal of $40 (Yr 2011$)/tonne of CO2 captured can be met by decreasing membrane module cost and by utilizing advanced CO2 capture solvents. In the second stage of the field test, an advanced solvent, Hitachi’s H3-1 was utilized. The use of H3-1 solvent increased mass transfer coefficient by 17% as compared to aMDEA solvent. The high mass transfer coefficient of H3-1 solvent combined with much more favorable solvent regeneration requirements, indicate that the projected savings achievable with membrane contactor process can be further improved. H3-1 solvent will be used in the next pilot-scale development phase. The integrated absorption/regeneration process design and high performance membrane contactors developed in the current bench

Far-infrared reflection-absorption spectroscopy of amorphous and polycrystalline gallium arsenide films

International Nuclear Information System (INIS)

Gregory, J.R.

1992-01-01

We have reported far-infrared reflection absorption spectra (30-320CM -1 ) at 30 and 310K for nine films of non-stoichiometric GaAs. The FIRRAS measurements were performed using the grazing incidence FIR double-modulation spectroscopy technique first described by DaCosta and Coleman. The films were fabricated by molecular beam deposition on metallized substrates for two As/Ga molecular beam flux ratios. The films were characterized by depth profilometry, IRAS, XRD, and x-ray microprobe analysis. Film thicknesses ranged from 800 to 5800 angstrom and compositions were 45-50% As for a MB flux ratio of 0.29 and 60-70% As for a ratio of 1.12. FIRRAS measurements were made and characterizations performed for as-deposited films and for 5 hour anneals at 473, 573, 673 and 723 degrees C. Vibrational spectra of the crystallized films were interpreted in terms of the exact reflectivity of a thin dielectric film on a conducting substrate, using a classical Lorentzian dielectric function for the response of the film. Resonances appearing in the open-quote forbidden close-quote region between the TO and LO frequencies were modelled with an effective medium approximation and are interpreted as arising from small-scale surface roughness. The behavior of the amorphous film spectra were examined within two models. The effective force constant model describes the variation of the reflection-absorption maxima with measured crystallite size in terms of the effective vibration frequency of 1-D atomic chains having force constants distributed according to the parameters of the crystalline-to-amorphous relaxation length and the crystalline to amorphous force constant ratio. The dielectric function continuum model uses the relaxation of the crystal momentum selection rule to calculate the reflection-absorption spectrum based on a dielectric function in which the oscillator strength is the normalized product of a constant dipole strength and the smoothed vibrational density of states

On the nature of absorption features toward nearby stars

Science.gov (United States)

Kohl, S.; Czesla, S.; Schmitt, J. H. M. M.

2016-06-01

Context. Diffuse interstellar absorption bands (DIBs) of largely unknown chemical origin are regularly observed primarily in distant early-type stars. More recently, detections in nearby late-type stars have also been claimed. These stars' spectra are dominated by stellar absorption lines. Specifically, strong interstellar atomic and DIB absorption has been reported in τ Boo. Aims: We test these claims by studying the strength of interstellar absorption in high-resolution TIGRE spectra of the nearby stars τ Boo, HD 33608, and α CrB. Methods: We focus our analysis on a strong DIB located at 5780.61 Å and on the absorption of interstellar Na. First, we carry out a differential analysis by comparing the spectra of the highly similar F-stars, τ Boo and HD 33608, whose light, however, samples different lines of sight. To obtain absolute values for the DIB absorption, we compare the observed spectra of τ Boo, HD 33608, and α CrB to PHOENIX models and carry out basic spectral modeling based on Voigt line profiles. Results: The intercomparison between τ Boo and HD 33608 reveals that the difference in the line depth is 6.85 ± 1.48 mÅ at the DIB location which is, however, unlikely to be caused by DIB absorption. The comparison between PHOENIX models and observed spectra yields an upper limit of 34.0 ± 0.3 mÅ for any additional interstellar absorption in τ Boo; similar results are obtained for HD 33608 and α CrB. For all objects we derive unrealistically large values for the radial velocity of any presumed interstellar clouds. In τ Boo we find Na D absorption with an equivalent width of 0.65 ± 0.07 mÅ and 2.3 ± 0.1 mÅ in the D2 and D1 lines. For the other Na, absorption of the same magnitude could only be detected in the D2 line. Our comparisons between model and data show that the interstellar absorption toward τ Boo is not abnormally high. Conclusions: We find no significant DIB absorption in any of our target stars. Any differences between modeled and

Absorption/desorption in sprays

International Nuclear Information System (INIS)

Naimpally, A.

1987-01-01

This survey paper shall seek to present the present state of knowledge concerning absorption and desorption in spray chambers. The first part of the paper presents the theories and formulas for the atomization and break-up of sprays in nozzles. Formulas for the average (sauter-mean) diameters are then presented. For the case of absorption processes, the formulas for the dimensionless mass transfer coefficients is in drops. The total; mass transfer is the total of the transfer in individual drops. For the case of desorption of sparingly soluble gases from liquids in a spray chamber, the mass transfer occurs in the spray just at the point of break-up of the jet. Formulas for the desorption of gases are presented

Experimental methodology for obtaining sound absorption coefficients

Directory of Open Access Journals (Sweden)

Carlos A. Macía M

2011-07-01

Full Text Available Objective: the authors propose a new methodology for estimating sound absorption coefficients using genetic algorithms. Methodology: sound waves are generated and conducted along a rectangular silencer. The waves are then attenuated by the absorbing material covering the silencer’s walls. The attenuated sound pressure level is used in a genetic algorithm-based search to find the parameters of the proposed attenuation expressions that include geometric factors, the wavelength and the absorption coefficient. Results: a variety of adjusted mathematical models were found that make it possible to estimate the absorption coefficients based on the characteristics of a rectangular silencer used for measuring the attenuation of the noise that passes through it. Conclusions: this methodology makes it possible to obtain the absorption coefficients of new materials in a cheap and simple manner. Although these coefficients might be slightly different from those obtained through other methodologies, they provide solutions within the engineering accuracy ranges that are used for designing noise control systems.

Is oral absorption of vigabatrin carrier-mediated?

DEFF Research Database (Denmark)

Nøhr, M. K.; Juul, R. V.; Thale, Z. I.

2015-01-01

by mechanistic non-linear mixed effects modelling, evaluating PAT1-ligands as covariates on the PK parameters with a full covariate modelling approach. The oral absorption of vigabatrin was adequately described by a Michaelis-Menten type saturable absorption. Using a Michaelis constant of 32.8 mM, the model......-mediated and if the proton-coupled amino acid transporter 1 (PAT1) was involved in the absorption processes. Vigabatrin (0.3-300 mg/kg) was administered orally or intravenously to Sprague Dawley rats in the absence or presence of PAT1-ligands l-proline, l-tryptophan or sarcosine. The PK profiles of vigabatrin were described...... estimated a maximal oral absorption rate (Vmax) of 64.6 mmol/min and dose-dependent bioavailability with a maximum of 60.9%. Bioavailability was 58.5-60.8% at 0.3-30 mg/kg doses, but decreased to 46.8% at 300 mg/kg. Changes in oral vigabatrin PK after co-administration with PAT1-ligands was explained...

Radiant absorption characteristics of corrugated curved tubes

Directory of Open Access Journals (Sweden)

Đorđević Milan Lj.

2017-01-01

Full Text Available The utilization of modern paraboloidal concentrators for conversion of solar radiation into heat energy requires the development and implementation of compact and efficient heat absorbers. Accurate estimation of geometry influence on absorption characteristics of receiver tubes is an important step in this process. This paper deals with absorption characteristics of heat absorber made of spirally coiled tubes with transverse circular corrugations. Detailed 3-D surface-to-surface Hemicube method was applied to compare radiation performances of corrugated and smooth curved tubes. The numerical results were obtained by varying the tube curvature ratio and incident radiant heat flux intensity. The details of absorption efficiency of corrugated tubes and the effect of curvature on absorption properties for both corrugated and smooth tubes were presented. The results may have significance to further analysis of highly efficient heat absorbers exposed to concentrated radiant heating. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 42006

Theory of strong-field attosecond transient absorption

International Nuclear Information System (INIS)

Wu, Mengxi; Chen, Shaohao; Camp, Seth; Schafer, Kenneth J; Gaarde, Mette B

2016-01-01

Attosecond transient absorption is one of the promising new techniques being developed to exploit the availability of sub-femtosecond extreme ultraviolet (XUV) pulses to study the dynamics of the electron on its natural time scale. The temporal resolution in a transient absorption setup comes from the control of the relative delay and coherence between pump and probe pulses, while the spectral resolution comes from the characteristic width of the features that are being probed. In this review we focus on transient absorption scenarios where an attosecond pulse of XUV radiation creates a broadband excitation that is subsequently probed by a few cycle infrared (IR) laser. Because the attosecond XUV pulses are locked to the IR field cycle, the exchange of energy in the laser–matter interaction can be studied with unprecedented precision. We focus on the transient absorption by helium atoms of XUV radiation around the first ionization threshold, where we can simultaneoulsy solve the time-dependent Schrödinger equation for the single atom response and the Maxwell wave equation for the collective response of the nonlinear medium. We use a time-domain method that allows us to treat on an equal footing all the different linear and nonlinear processes by which the medium can exchange energy with the fields. We present several simple models, based on a few-level system interacting with a strong IR field, to explain many of the novel features found in attosecond transient absorption spectrograms. These include the presence of light-induced states, which demonstrate the ability to probe the dressed states of the atom. We also present a time-domain interpretation of the resonant pulse propagation features that appear in absorption spectra in dense, macroscopic media. We close by reviewing several recent experimental results that can be explained in terms of the models we discuss. Our aim is to present a road map for understanding future attosecond transient absorption

A new in vitro lipid digestion - in vivo absorption model to evaluate the mechanisms of drug absorption from lipid-based formulations.

Science.gov (United States)

Crum, Matthew F; Trevaskis, Natalie L; Williams, Hywel D; Pouton, Colin W; Porter, Christopher J H

2016-04-01

In vitro lipid digestion models are commonly used to screen lipid-based formulations (LBF), but in vitro-in vivo correlations are in some cases unsuccessful. Here we enhance the scope of the lipid digestion test by incorporating an absorption 'sink' into the experimental model. An in vitro model of lipid digestion was coupled directly to a single pass in situ intestinal perfusion experiment in an anaesthetised rat. The model allowed simultaneous real-time analysis of the digestion and absorption of LBFs of fenofibrate and was employed to evaluate the influence of formulation digestion, supersaturation and precipitation on drug absorption. Formulations containing higher quantities of co-solvent and surfactant resulted in higher supersaturation and more rapid drug precipitation in vitro when compared to those containing higher quantities of lipid. In contrast, when the same formulations were examined using the coupled in vitro lipid digestion - in vivo absorption model, drug flux into the mesenteric vein was similar regardless of in vitro formulation performance. For some drugs, simple in vitro lipid digestion models may underestimate the potential for absorption from LBFs. Consistent with recent in vivo studies, drug absorption for rapidly absorbed drugs such as fenofibrate may occur even when drug precipitation is apparent during in vitro digestion.

Determination of the separation between the soft X-ray K-emission and K-absorption edges in beryllium metal from self-absorption studies

International Nuclear Information System (INIS)

Crisp, R.S.

1979-01-01

Recent theoretical studies have aroused interest in the phonon broadening of the soft X-ray emission and absorption edges and the shift between them. Using a self-absorption technique a separation of about 0.2 eV is shown to exist between the edges in Be metal. This shift explains the very small self-absorption effects previously observed in Be. (Auth.)

Absorptive form factors for high-energy electron diffraction

International Nuclear Information System (INIS)

Bird, D.M.; King, Q.A.

1990-01-01

The thermal diffuse scattering contribution to the absorptive potential in high-energy electron diffraction is calculated in the form of an absorptive contribution to the atomic form factor. To do this, the Einstein model of lattice vibrations is used, with isotropic Debye-Waller factors. The absorptive form factors are calculated as a function of scattering vector s and temperature factor M on a grid which enables polynomial interpolation of the results to be accurate to better than 2% for much of the ranges 0≤Ms 2 ≤6 and 0≤M≤2 A 2 . The computed values, together with an interpolation routine, have been incorporated into a Fortran subroutine which calculates both the real and absorptive form factors for 54 atomic species. (orig.)

Luminescence and optical absorption determination in porous silicon

International Nuclear Information System (INIS)

Nogal, U.; Calderon, A.; Marin, E.; Rojas T, J. B.; Juarez, A. G.

2012-10-01

We applied the photoacoustic spectroscopy technique in order to obtain the optical absorption spectrum in porous silicon samples prepared by electrochemical anodic etching on n-type, phosphorous doped, (100)-oriented crystal-line silicon wafer with thickness of 300 μm and 1-5 ωcm resistivity. The porous layers were prepared with etching times of 13, 20, 30, 40 and 60 minutes. Also, we realized a comparison among the optical absorption spectrum with the photoluminescence and photo reflectance ones, both obtained at room temperature. Our results show that the absorption spectrum of the samples of porous silicon depends notably of the etching time an it consist of two distinguishable absorption bands, one in the Vis region and the other one in the UV region. (Author)

Comparison and Analysis of Lithium Bromide-water Absorption Chillers Using Plastic Heat Transfer Tubes and Traditional Lithium Bromide-water Absorption Chillers

OpenAIRE

Xue-dong Zhang

2010-01-01

There are extensive applications of lithium bromide-water absorption chillers in industry, but the heat exchangers corrosion and refrigerating capacity loss are very difficult to be solved. In this paper, an experiment was conducted by using plastic heat transfer tubes instead of copper tubes. As an example, for a lithium bromide-water absorption chiller of refrigerating capacity of 35kW, the correlative performance of the lithium bromide-water absorption chiller using pl...

Absorption of orally administered 65Zn by normal human subjects

International Nuclear Information System (INIS)

Aamodt, R.L.; Rumble, W.F.; Johnston, G.S.; Markley, E.J.; Henkin, R.I.

1981-01-01

Despite studies by several investigators of human gastrointestinal 65Zn absorption, implications of these data for evaluation of functional zinc status are unclear because limited numbers of normal subjects have been studied. To evaluated zinc absorption in normal humans, 75 subjects (31 women, 44 men, ages 18 to 84 yr) were given 10 micro Ci carrier-free 65Zn orally after an overnight fast. Absorption calculated from total body retention measured 7, 14, and 21 days after administration of tracer was 65 +/- 11% (mean +/- 1 SD), range from 40 to 86%. Comparison of these results with those for patients with a variety of diseases indicate that patients exhibit a wider range of absorption and, in four of six studies patients exhibit decreased mean zinc absorption. These results of gastrointestinal zinc absorption in a large number of normal humans offer a basis for a clearer comparison with data from patients who exhibit abnormalities of zinc absorption

Enantiopure distorted ribbon-shaped nanographene combining two-photon absorption-based upconversion and circularly polarized luminescence.

Science.gov (United States)

Cruz, Carlos M; Márquez, Irene R; Mariz, Inês F A; Blanco, Victor; Sánchez-Sánchez, Carlos; Sobrado, Jesús M; Martín-Gago, José A; Cuerva, Juan M; Maçôas, Ermelinda; Campaña, Araceli G

2018-04-28

Herein we describe a distorted ribbon-shaped nanographene exhibiting unprecedented combination of optical properties in graphene-related materials, namely upconversion based on two-photon absorption (TPA-UC) together with circularly polarized luminescence (CPL). The compound is a graphene molecule of ca. 2 nm length and 1 nm width with edge defects that promote the distortion of the otherwise planar lattice. The edge defects are an aromatic saddle-shaped ketone unit and a [5]carbohelicene moiety. This system is shown to combine two-photon absorption and circularly polarized luminescence and a remarkably long emission lifetime of 21.5 ns. The [5]helicene is responsible for the chiroptical activity while the push-pull geometry and the extended network of sp 2 carbons are factors favoring the nonlinear absorption. Electronic structure theoretical calculations support the interpretation of the results.

Variations in the spectral values of specific absorption of phytoplankton

Digital Repository Service at National Institute of Oceanography (India)

Sathyendranath, S.; Lazzara, L.; Prieur, L.

Absorption spectra of laboratory cultures of eight species of phytoplankton were studied. These spectra, normalized per unit of chlorophyll a concentration (specific absorption) show variability in magnitude and spectral form. Specific absorption...

Controlling enhanced absorption in graphene metamaterial

Science.gov (United States)

Zhou, Qihui; Liu, Peiguo; Bian, Li-an; Liu, Hanqing; Liu, Chenxi; Chen, Genghui

2018-04-01

In this paper, a controllable terahertz (THz) metamaterial absorber (MA) is designed with the circuit analog method. Taking advantage of the patterned graphene on SiO2/doped Si/polyimide substrates with a gold reflector, the controllable MA achieves perfect absorption at 0.75 THz. The chemical potential of graphene is regulated by controlling the voltage between graphene and doped Si layers. As the chemical potential varies from 0 eV to 0.5 eV, the MA is changed from reflection (0.99). The distributions of surface current and electric field are illustrated to analyze the resonant characteristic of patterned graphene. According to the resonant characteristic, we introduce patterned graphene elements with different dimension in a unit cell, which effectively extends the effective absorption bandwidth (absorption > 0 . 9) from 0.67-0.93 THz to 0.52-0.95 THz. Moreover, replacing part of the graphene structure with gold, the switchable MA is turned into a frequency tunable MA. The absorption peak moves from 0.62 THz to 0.92 THz as the chemical potential increases from 0.1 eV to 0.5 eV. These designs overcome limitation of traditional absorbers and exhibit great potentials in many practical applications.

Realistic absorption coefficient of ultrathin films

International Nuclear Information System (INIS)

Cesaria, M; Caricato, A P; Martino, M

2012-01-01

Both a theoretical algorithm and an experimental procedure are discussed of a new route to determine the absorption/scattering properties of thin films deposited on transparent substrates. Notably, the non-measurable contribution of the film–substrate interface is inherently accounted for. While the experimental procedure exploits only measurable spectra combined according to a very simple algorithm, the theoretical derivation does not require numerical handling of the acquired spectra or any assumption on the film homogeneity and substrate thickness. The film absorption response is estimated by subtracting the measured absorption spectrum of the bare substrate from that of the film on the substrate structure but in a non-straightforward way. In fact, an assumption about the absorption profile of the overall structure is introduced and a corrective factor accounting for the relative film-to-substrate thickness. The method is tested on films of a well known material (ITO) as a function of the film structural quality and influence of the film–substrate interface, both deliberately changed by thickness tuning and doping. Results are found fully consistent with information obtained by standard optical analysis and band gap values reported in the literature. Additionally, comparison with a conventional method demonstrates that our route is generally more accurate even if particularly suited for very thin films. (paper)

Realistic absorption coefficient of ultrathin films

Science.gov (United States)

Cesaria, M.; Caricato, A. P.; Martino, M.

2012-10-01

Both a theoretical algorithm and an experimental procedure are discussed of a new route to determine the absorption/scattering properties of thin films deposited on transparent substrates. Notably, the non-measurable contribution of the film-substrate interface is inherently accounted for. While the experimental procedure exploits only measurable spectra combined according to a very simple algorithm, the theoretical derivation does not require numerical handling of the acquired spectra or any assumption on the film homogeneity and substrate thickness. The film absorption response is estimated by subtracting the measured absorption spectrum of the bare substrate from that of the film on the substrate structure but in a non-straightforward way. In fact, an assumption about the absorption profile of the overall structure is introduced and a corrective factor accounting for the relative film-to-substrate thickness. The method is tested on films of a well known material (ITO) as a function of the film structural quality and influence of the film-substrate interface, both deliberately changed by thickness tuning and doping. Results are found fully consistent with information obtained by standard optical analysis and band gap values reported in the literature. Additionally, comparison with a conventional method demonstrates that our route is generally more accurate even if particularly suited for very thin films.

Absorption from iron tablets given with different types of meals

International Nuclear Information System (INIS)

Hallberg, L.; Bjoern-Rasmussen, E.; Ekenved, G.; Garby, L.; Rossander, L.; Pleehachinda, R.; Suwanik, R.; Arvidsson, B.

1978-01-01

The absorption from iron tablets given with 5 types of meals was studied in 153 subjects. The meals were: a hamburger meal with beans and potatoes, a simple breakfast meal, a Latin American meal composed of black beans, rice and maize and two Southeast Asian meals composed of rice, vegetables, and spices served with and without fish. The groups were directly compared by relating the absorption from the iron tablets to the absorption from a standardized reference dose of iron given on an empty stomach. The composition of meals with respect to content of meat or fish or the presence of large amounts of phytates seemed to have no influence on the absorption of iron from tablets. The absorption from iron tablets was about 40% higher when they were given with rice meals than when they were given with the other meals studied. The average decrease in absorption by meals was about 50-60% based on a comparison when tablets were given on an empty stomach. When tablets from which the iron was released more slowly were used, the absorption increased by about 30% except when they were given with rice meals, where the absorption was unchanged. The differences among the meals in their effect on the absorption of iron from tablets thus disappeared when the slow-release tablets were given. (author)

Absorption from iron tablets given with different types of meals

Energy Technology Data Exchange (ETDEWEB)

Hallberg, L; Bjoern-Rasmussen, E; Ekenved, G; Garby, L; Rossander, L; Pleehachinda, R; Suwanik, R; Arvidsson, B

1978-01-01

The absorption from iron tablets given with 5 types of meals was studied in 153 subjects. The meals were: a hamburger meal with beans and potatoes, a simple breakfast meal, a Latin American meal composed of black beans, rice and maize and two Southeast Asian meals composed of rice, vegetables, and spices served with and without fish. The groups were directly compared by relating the absorption from the iron tablets to the absorption from a standardized reference dose of iron given on an empty stomach. The composition of meals with respect to content of meat or fish or the presence of large amounts of phytates seemed to have no influence on the absorption of iron from tablets. The absorption from iron tablets was about 40% higher when they were given with rice meals than when they were given with the other meals studied. The average decrease in absorption by meals was about 50-60% based on a comparison when tablets were given on an empty stomach. When tablets from which the iron was released more slowly were used, the absorption increased by about 30% except when they were given with rice meals, where the absorption was unchanged. The differences among the meals in their effect on the absorption of iron from tablets thus disappeared when the slow-release tablets were given.

Absorption from iron tablets given with different types of meals.

Science.gov (United States)

Hallberg, L; Björn-Rasmussen, E; Ekenved, G; Garby, L; Rossander, L; Pleehachinda, R; Suwanik, R; Arvidsson, B

1978-09-01

The absorption of iron from tablets given with 5 types of meals was studied in 153 subjects. The meals were: a hamburger meal with beans and potatoes, a simple breakfast meal, a Latin American meal composed of black beans, rice and maize and two Southeast Asian meals composed of rice, vegetables and spices served with and without fish. The groups were directly compared by relating the absorption from the iron tablets to the absorption from a standardized reference dose of iron given on an empty stomach. The composition of meals with respect to content of meat or fish or the presence of large amounts of phytates seemed to have no influence on the absorption of iron from tablets. The absorption from iron tablets was about 40% higher when they were given with rice meals than when they were given with the other meals studied. The average decrease in absorption by meals was about 50-60% based on a comparison when tablets were given on an empty stomach. When tablets from which the iron was released more slowly were used, the absorption increased by about 30% except when they were given with rice meals, where the absorption was unchanged. The differences among the meals in their effect on the absorption of iron from tablets thus disappeared when the slow-release tablets were given.

Gold analysis by the gamma absorption technique

International Nuclear Information System (INIS)

Kurtoglu, Arzu; Tugrul, A.B.

2003-01-01

Gold (Au) analyses are generally performed using destructive techniques. In this study, the Gamma Absorption Technique has been employed for gold analysis. A series of different gold alloys of known gold content were analysed and a calibration curve was obtained. This curve was then used for the analysis of unknown samples. Gold analyses can be made non-destructively, easily and quickly by the gamma absorption technique. The mass attenuation coefficients of the alloys were measured around the K-shell absorption edge of Au. Theoretical mass attenuation coefficient values were obtained using the WinXCom program and comparison of the experimental results with the theoretical values showed generally good and acceptable agreement

Comparison of water absorption methods: testing the water absorption of recently quarried and weathered porous limestone on site and under laboratory conditions

Science.gov (United States)

Rozgonyi-Boissinot, Nikoletta; Agárdi, Tamás; Karolina Cebula, Ágnes; Török, Ákos

2017-04-01

The water absorption of weathering sensitive stones is a critical parameter that influences durability. The current paper compares different methods of water absorption tests by using on site and laboratory tests. The aims of the tests were to assess the water absorption of un-weathered quarry stones and various weathering forms occurring on porous limestone monuments. For the tests a Miocene porous limestone was used that occurs in Central and Western Hungary and especially near and in Budapest. Besides the Hungarian occurrences the same or very similar porous limestones are found in Austria, Slovakia and in the Czech Republic. Several quarries were operating in these countries. Due to the high workability the stone have been intensively used as construction material from the Roman period onward. The most prominent monuments made of this stone were built in Vienna and in Budapest during the 18th -19th century and in the early 20th century. The high porosity and the micro-fabric of the stone make it prone to frost- and salt weathering. Three different limestone types were tested representing coarse-, medium- and fine grained lithologies. The test methods included Rilem tube (Karsten tube) tests and capillary water absorption tests. The latter methodology has been described in detail in EN 1925:2000. The test results of on-site tests of weathered porous limestone clearly show that the water absorption of dissolved limestone surfaces and crumbling or micro-cracked limestone is similar. The water absorption curves have similar inclinations marking high amount of absorbed water. To the contrary, the white weathering crusts covered stone blocks and black crusts have significantly lower water absorptions and many of these crusts are considered as very tight almost impermeable surfaces. Capillary water absorption tests in the laboratory allowed the determination of maximum water absorption of quarried porous limestone. Specimens were placed in 3 mm of water column and the

Time-resolved absorption measurements on OMEGA

International Nuclear Information System (INIS)

Jaanimagi, P.A.; DaSilva, L.; Delettrez, J.; Gregory, G.G.; Richardson, M.C.

1986-01-01

Time-resolved measurements of the incident laser light that is scattered and/or refracted from targets irradiated by the 24 uv-beam OMEGA laser at LLE, have provided some interesting features related to time-resolved absorption. The decrease in laser absorption characteristic of irradiating a target that implodes during the laser pulse has been observed. The increase in absorption expected as the critical density surface moves from a low to a high Z material in the target has also been noted. The detailed interpretation of these results is made through comparisons with simulation using the code LILAC, as well as with streak data from time-resolved x-ray imaging and spectroscopy. In addition, time and space-resolved imaging of the scattered light yields information on laser irradiation uniformity conditions on the target. The report consists of viewgraphs

Selective gas absorption by ionic liquids

DEFF Research Database (Denmark)

Shunmugavel, Saravanamurugan; Kegnæs, Søren; Due-Hansen, Johannes

2010-01-01

Reversible absorption performance for the flue gas components CO 2, NO and SO2 has been tested for several different ionic liquids (ILs) at different temperatures and flue gas compositions. Furthermore, different porous, high surface area carriers have been applied as supports for the ionic liquids...... to obtain Supported Ionic Liquid-Phase (SILP) absorber materials. The use of solid SILP absorbers with selected ILs were found to significantly improve the absorption capacity and sorption dynamics at low flue gas concentration, thus making the applicability of ILs viable in technical, continuous flow...... processes for flue gas cleaning. The results show that CO 2, NO and SO2 can be reversible and selective absorbed using different ILs and that Supported Ionic Liquid-Phase (SILP) absorbers are promising materials for industrial flue gas cleaning. Absorption/desorption dynamics can be tuned by temperatures...

Lithium absorption by the rabbit gall-bladder

DEFF Research Database (Denmark)

Hansen, C P; Holstein-Rathlou, N H; Skøtt, O

1991-01-01

Lithium (Li+) absorption across the low-resistance epithelium of the rabbit gall-bladder was studied in order to elucidate possible routes and mechanisms of Li+ transfer. Li+ at a concentration of 0.4 mM in both mucosal and serosal media did not affect isosmotic mucosa-to-serosa fluid absorption...

Absorption of plutonium in the iron-deficient rat

International Nuclear Information System (INIS)

Ragan, H.A.

1977-01-01

Iron deficiency did not enhance absorption of plutonium following intragastric gavage of rats. Absorption of plutonium citrate in both control and iron-deficient rats was about 0.03% of the administered dose

Vehicle effects on human stratum corneum absorption and skin penetration.

Science.gov (United States)

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

2017-05-01

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.

Absorption Efficiency of Receiving Antennas

DEFF Research Database (Denmark)

Andersen, Jørgen Bach; Frandsen, Aksel

2005-01-01

A receiving antenna with a matched load will always scatter some power. This paper sets an upper and a lower bound on the absorption efficiency (absorbed power over sum of absorbed and scattered powers), which lies between 0 and 100% depending on the directivities of the antenna and scatter...... patterns. It can approach 100% as closely as desired, although in practice this may not be an attractive solution. An example with a small endfire array of dipoles shows an efficiency of 93%. Several examples of small conical horn antennas are also given, and they all have absorption efficiencies less than...

Calcium absorption response to cholecalciferol supplementation in hemodialysis.

Science.gov (United States)

Armas, Laura A G; Zena, Mohsen; Lund, Richard; Heaney, Robert P

2013-06-01

Recent understanding of extrarenal production of calcitriol has led to the use of more vitamin D supplementation in CKD populations. This paper reports the effect of cholecalciferol supplementation on calcium absorption. Paired calcium absorption tests were done before and after 12-13 weeks of 20,000 IU weekly cholecalciferol supplementation in 30 participants with stage 5 CKD on hemodialysis. The study was conducted from April to December of 2011. Calcium absorption was tested with a standardized meal containing 300 mg calcium carbonate intrinsically labeled with (45)Ca; 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D were measured. 25-Hydroxyvitamin D rose from 14.2 ng/ml (11.5-18.5) at baseline to 49.3 ng/ml (42.3-58.1) at the end of the study (P<0.001). 1,25-Dihydroxyvitamin D rose from 15.1 (10.5-18.8) pg/ml at baseline to 20.5 (17.0-24.7) pg/ml at the end of the study (P<0.001). The median baseline calcium absorption was 12% (7%-17%) and 12% (7%-16%) at the end of study. Patients with stage 5 CKD on hemodialysis had very low calcium absorption values at baseline, and cholecalciferol supplementation that raised 25(OH)D levels to 50 ng/ml had no effect on calcium absorption.

Dynamics of water absorption through superabsorbent polymer

Science.gov (United States)

Chang, Sooyoung; Kim, Wonjung

2017-11-01

Superabsorbent polymers (SAPs) consist of hydrophilic cross-linked polymer networks that can absorb and retain a great amount of water relative to their own mass, so that they are widely used for disposable diapers and holding soil moisture in agriculture. SAPs are typically available in the form of submillimeter-sized particles, and the water absorption is driven by capillary flows between particles as well as diffusion that entail swelling. Although the control of water absorption of SAPs is important in engineering applications, but the dynamics of water absorption in SAP particles has not been fully understood. We examine the dynamics of the water absorption of sodium polyacrylate, one of the most common SAP. We experimentally measured the water absorption of sodium polyacrylate particles in one-dimensional confined channel. The water flows through the particles were analyzed by capillarity dominant at the early stage and by diffusion involving volume expansion critical at a later stage. The results provide a quantitative basis of the hydrodynamic analysis of the water flow through SAP particles from a macroscopic point of view, facilitating the prediction of water uptake of SAPs in hygienic and agricultural applications. This work was supported by the National Research Foundation of Korea (NRF) Grant funded by the Korea government (MSIP) (No.2015R1A2A2A04006181).

Optical absorption in recycled waste plastic polyethylene

Science.gov (United States)

Aji, M. P.; Rahmawati, I.; Priyanto, A.; Karunawan, J.; Wati, A. L.; Aryani, N. P.; Susanto; Wibowo, E.; Sulhadi

2018-03-01

We investigated the optical properties of UV spectrum absorption in recycled waste plastic from polyethylene polymer type. Waste plastic polyethylene showed an optical spectrum absorption after it’s recycling process. Spectrum absorption is determined using spectrophotometer UV-Nir Ocean Optics type USB 4000. Recycling method has been processed using heating treatment around the melting point temperature of the polyethylene polymer that are 200°C, 220°C, 240°C, 260°C, and 280°C. In addition, the recycling process was carried out with time variations as well, which are 1h, 1.5h, 2h, and 2.5h. The result of this experiment shows that recycled waste plastic polyethylene has a spectrum absorption in the ∼ 340-550 nm wavelength range. The absorbance spectrum obtained from UV light which is absorbed in the orbital n → π* and the orbital π → π*. This process indicates the existence of electron transition phenomena. This mechanism is affected by the temperature and the heating time where the intensity of absorption increases and widens with the increase of temperature and heating time. Furthermore this study resulted that the higher temperature affected the enhancement of the band gap energy of waste plastic polyethylene. These results show that recycled waste plastic polyethylene has a huge potential to be absorber materials for solar cell.

Determination of the separation between the soft X-ray K-emission and K-absorption edges in beryllium metal from self-absorption studies

International Nuclear Information System (INIS)

Crisp, R.S.

1979-01-01

Recent theoretical studies have aroused interest in the phonon broadening of the soft X-ray emission and absorption edges and the shift between them. Using a self-absorption technique a separation of about 0.2 eV is shown to exist between the edges in Be metal. This shift explains the very small self-absorption effects previously observed in Be by Crisp (1977). (Auth.)

Zeeman atomic absorption spectrometry

International Nuclear Information System (INIS)

Hadeishi, T.; McLaughlin, R.

1978-08-01

The design and development of a Zeeman atomic absorption spectrometer for trace element analysis are described. An instruction manual is included which details the operation, adjustment, and maintenance. Specifications and circuit diagrams are given

The application of atomic absorption spectrometry to chemical analysis

International Nuclear Information System (INIS)

Walsh, A.

1980-01-01

YhThe history of the development of atomic absorption methods of elemental analysis is outlined. The theoretical basis of atomic absorption methods is discussed and the principle of modern methods of atomic absorption measurements is described. The advantages, scope and limations of these methods are discussed. Related methods based on the measurement of atomic fluorescence are also described

Molecular absorption spectra of beryllium, cerium, lanthanum, iron, and platinum salts

International Nuclear Information System (INIS)

Daidoji, Hidehiro

1980-01-01

The absorption spectra of some salts of beryllium, cerium, lanthanum, iron and platinum in air-acetylene flame were measured in the wavelength range from 200 to 400 nm. A Hitachi 207 type atomic absorption spectrophotometer was used. A deuterium lamp, a home-made continuous radiation lamp and some hollow cathode lamps were used as light sources. The new molecular absorption spectra of cerium, lanthanum and platinum and the absorption spectra due to Be(OH) 2 , LaO, PtH, FeO and FeCl in 200-400 nm region were obtained. Emission spectra of CeO, LaO and FeOH were also obtained. These molecular absorption bands were estimated as absorption errors of maximum 15 times to the sensitivity of each elements in atomic absorption spectrometry. In addition, spectral line interferences of iron were observed in atomic absorption spectrometry of Zn, Cd, Ni, Cu and Cr. (author)

Industrial trigeneration using ammonia-water absorption refrigeration systems (AAR)

International Nuclear Information System (INIS)

Colonna, Piero; Gabrielli, Sandro

2003-01-01

In many industrial processes there is a simultaneous need for electric power and refrigeration at low temperatures. Examples are in the food and chemical industries. Nowadays the increase in fuel prices and the ecological implications are giving an impulse to energy technologies that better exploit the primary energy source and integrated production of utilities should be considered when designing a new production plant. The number of so-called trigeneration systems installations (electric generator and absorption refrigeration plant) is increasing. If low temperature refrigeration is needed (from 0 to -40 deg. C), ammonia-water absorption refrigeration plants can be coupled to internal combustion engines or turbogenerators. A thermodynamic system study of trigeneration configurations using a commercial software integrated with specifically designed modules is presented. The study analyzes and compares heat recovery from the primary mover at different temperature levels. In the last section a simplified economic assessment that takes into account disparate prices in European countries compares conventional electric energy supply from the grid and optimized trigeneration plants in one test case (10 MW electric power, 7000 h/year)

Structural slow light can enhance Beer-Lambert absorption

OpenAIRE

Dicaire Isabelle; Chin Sanghoon; Thévenaz Luc

2011-01-01

We experimentally demonstrate that structural slow light can enhance Beer-Lambert absorption. A 4-fold reduction of the group velocity induced by mere cavity effects has caused an increase of molecular absorption by 130%.

Absorption of l-methionine from the human small intestine

Science.gov (United States)

Schedl, Harold P.; Pierce, Charles E.; Rider, Alan; Clifton, James A.

1968-01-01

Absorption of L-methionine was measured in all parts of the human small intestine using transintestinal intubation and perfusion. In four normal subjects, adsorption was higher in the proximal than in the distal intestine. In two patients with nontropical sprue in relapse, there was a proximal zone of low absorption with higher absorption distally. In all parts of the small intestine, absorption showed rate-limiting kinetics as methionine concentration was increased. In normal subjects, the proximal Km (Michaelis constant) was more than 3 times higher than the distal, which suggests a difference in transport mechanisms between the two segments. PMID:12066784

Angular absorption of iridium - ICW12 needles: practical considerations

International Nuclear Information System (INIS)

Szymczyk, W.; Lesiak, J.

1984-01-01

An analysis was made of two potential sources of error in Ir 192 dosimetry: the effect of angular absorption and the differences in the ionization constants found in literature. Corrections for selfabsorption in the ICW12 iridium source were determined from measurements and calculations. It was found that the decrease in the dose caused by the angular absorption in the central therapeutic area of a typical implantation can exceed 5 percent. The need for employing the concept of ''constant exposure rate'' is stressed as well as that for using angular absorption in the form of absorption. 13 refs., 6 figs., 1 tab. (author)

X-ray absorption intensity at high-energy region

International Nuclear Information System (INIS)

Fujikawa, Takashi; Kaneko, Katsumi

2012-01-01

We theoretically discuss X-ray absorption intensity in high-energy region far from the deepest core threshold to explain the morphology-dependent mass attenuation coefficient of some carbon systems, carbon nanotubes (CNTs), highly oriented pyrolytic graphite (HOPG) and fullerenes (C 60 ). The present theoretical approach is based on the many-body X-ray absorption theory including the intrinsic losses (shake-up losses). In the high-energy region the absorption coefficient has correction term dependent on the solid state effects given in terms of the polarization part of the screened Coulomb interaction W p . We also discuss the tail of the valence band X-ray absorption intensity. In the carbon systems C 2s contribution has some influence on the attenuation coefficient even in the high energy region at 20 keV.

Determination of optical absorption coefficient with focusing photoacoustic imaging.

Science.gov (United States)

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

2012-06-01

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

Light absorption and scattering mechanisms in laser fusion plasmas

International Nuclear Information System (INIS)

Barnes, C.; Estabrook, K.G.; Kruer, W.L.; Langdon, A.B.; Lasinski, B.F.; Max, C.E.; Randall, C.; Thomson, J.J.

1977-01-01

The picture of laser light absorption and scattering which is emerging from theory and computer simulation studies of laser-plasma interactions is described. On the subject of absorption, we discuss theoretical and experimental evidence that resonance absorption in a steepened density profile is a dominant absorption mechanism. Recent work also indicates the presence of critical surface ripples, which we study using two and three dimensional computer simulations. Predictions of hot electron spectra due to resonance absorption are described, as are effects of plasma outflow. We then discuss two regimes where stimulated scattering may occur. Brillouin scattering is expected in the underdense target blow-off, for long laser pulses, and is limited by ion heating. Raman scattering in the background gas of a reactor target chamber is predicted to be at most a 10 percent effect for 1 μm lasers

Does lead use the intestinal absorptive pathways of iron? Impact of iron status on murine 210Pb and 59Fe absorption in duodenum and ileum in vivo

International Nuclear Information System (INIS)

Elsenhans, Bernd; Janser, Heinz; Windisch, Wilhelm; Schuemann, Klaus

2011-01-01

Highlights: → Absorption of 210 Pb increases much less than that of 59 Fe in murine duodena. → 210 Pb-absorption is almost equally high in murine duodenal and ileal segments. → 59 Fe absorption is much lower in ileal than in duodenal segments. → There must be an additional DMT1-independet pathway for intestinal Pb absorption. -- Abstract: Background: Human isotope studies and epidemiological trials are controversial as to whether lead absorption shares the absorptive pathways of iron and whether body lead content can be reduced by iron supplementation. Aim: To compare the impact of iron-deficiency on 59 Fe- and 210 Pb-absorption rates in duodenal and ileal segments. Methods: 59 Fe- and 210 Pb-absorption was determined in ligated duodenal and ileal segments from juvenile and adult iron-deficient and iron-adequate C57Bl6 wild-type mice (n = 6) in vivo at luminal concentrations corresponding to human exposure (Fe: 1 and 100 μmol/L; Pb: 1 μmol/L). Results and discussion: 59 Fe-absorption increased 10-15-fold in iron-deficient duodena from adult and adolescent mice. Ileal 59 Fe-absorption was 4-6 times lower than in iron-adequate duodena showing no adaptation to iron-deficiency. This in accordance to expectation as the divalent metal transport 1 (DMT1) shows low ileal expression levels. Juvenile 59 Fe-absorption was about twice as high as in adult mice. In contrast, duodenal 210 Pb-absorption was increased only 1.5-1.8-fold in iron-deficiency in juvenile and adult mice and, again in contrast to 59 Fe, ileal 210 Pb-absorption was as high as in iron-adequate duodena. Conclusions: The findings suggest a DMT1-independent pathway to mediate lead absorption along the entire small intestine in addition to DMT1-mediated duodenal uptake. Ileal lead absorption appears substantial, due the much longer residence of ingesta in the distal small intestine. Differences in lead-solubility and -binding to luminal ligands can, thus, explain the conflicting findings regarding the

Water analysis. Determination of elements by atomic absorption

International Nuclear Information System (INIS)

Anon.

Analysis of homogeneous water solutions (plain water, polluted waters, effluents...) by atomic absorption spectrometry with correction for non specific absorption. The quantity ratio is determined by comparison with standard solutions, correction tables are given [fr

Absorptive products

International Nuclear Information System (INIS)

Assarsson, P.G.; King, P.A.

1976-01-01

Applications for hydrophile gels produced by the radiation induced cross-linking in aqueous solution of polyethylene oxide and starch, as described in Norwegian patent 133501 (INIS RN 281494), such as sanitary napkins (diapers) and sanitary towels, are discussed. The process itself is also discussed and results, expressed as the percentage of insoluble gel and its absorptive capacity for saline solution as functions of the ratio of polyethylene oxide to starch and the radiation dose, are presented. (JIW)

Cosmological Evolution of QSO Absorption Systems

Science.gov (United States)

Stengler-Larrea, Erik

1995-08-01

First, the evolution with cosmic time of the hydrogen clouds which produce the Lyman-alpha absorption lines is studied in dependence on the strength of these lines. From the analysis it is concluded that the results show no evidence of a dependence in the sense of stronger lines evolving faster, although for the resolution at which the used observations were done, it can not be ruled out. Within the same analysis, a distribution of the Doppler parameter of the lines was obtained, with large values and a wide spread. This parameter being an indicator of the gas temperature, this result is in accordance with high temperatures and, consequently, large ionised fractions and a large fraction of the baryonic matter of the universe being associated with these clouds. However, recent high resolution studies seem to reveal that much lower temperatures are characteristic of the clouds. The main content of this thesis, however, focuses on the redshift evolution of the absorbing systems producing absorption at the Lyman limit and of the amount of CIV producing CIV absorption lines. Regarding the CIV absorbers, previous predictions on the effects underlying their redshift distribution pointed to an increase with redshift of the absorbing column densities. In this thesis the first direct measurements of such column densities by profile fitting of a large number of absorption systems (73) are presented, confirming the predictions of a decrease of at least a factor of 3 between z=1.5 and z=3.0. The study on the evolution of Lyman limit absorption systems (LLSs) puts an end to previous discrepancies between the results of different groups. Both a smooth single power law dependence of the LLS number density on redshift indicating no evolution in number density for 0.4 Team of the HST Key Project on QSO absorption lines, and in particular to estimate the necessary exposure times, the magnitudes of several of these objects had to be re-measured. The acquisition of their images and the

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

Science.gov (United States)

Abitan, Haim; Bohr, Henrik; Buchhave, Preben

2008-10-10

The Beer-Lambert-Bouguer absorption law, known as Beer's law for absorption in an optical medium, is precise only at power densities lower than a few kW. At higher power densities this law fails because it neglects the processes of stimulated emission and spontaneous emission. In previous models that considered those processes, an analytical expression for the absorption law could not be obtained. We show here that by utilizing the Lambert W-function, the two-level energy rate equation model is solved analytically, and this leads into a general absorption law that is exact because it accounts for absorption as well as stimulated and spontaneous emission. The general absorption law reduces to Beer's law at low power densities. A criterion for its application is given along with experimental examples. (c) 2008 Optical Society of America

Numerical study of surface plasmon enhanced nonlinear absorption and refraction.

Science.gov (United States)

Kohlgraf-Owens, Dana C; Kik, Pieter G

2008-07-07

Maxwell Garnett effective medium theory is used to study the influence of silver nanoparticle induced field enhancement on the nonlinear response of a Kerr-type nonlinear host. We show that the composite nonlinear absorption coefficient, beta(c), can be enhanced relative to the host nonlinear absorption coefficient near the surface plasmon resonance of silver nanoparticles. This enhancement is not due to a resonant enhancement of the host nonlinear absorption, but rather due to a phase shifted enhancement of the host nonlinear refractive response. The enhancement occurs at the expense of introducing linear absorption, alpha(c), which leads to an overall reduced figure of merit beta(c)/alpha(c) for nonlinear absorption. For thin (< 1 microm) composites, the use of surface plasmons is found to result in an increased nonlinear absorption response compared to that of the host material.

Mid-IR Absorption Cross-Section Measurements of Hydrocarbons

KAUST Repository

Alrefae, Majed Abdullah

2013-01-01

-known at combustion-relevant conditions. Absorption cross-section is an important spectroscopic quantity and has direct relation to the species concentration. In this work, the absorption cross-sections of basic hydrocarbons are measured using Fourier Transform

Use of a standard meal to study iron absorption in humans

International Nuclear Information System (INIS)

Reddy, M.B.; Cook, J.D.

1994-01-01

Iron absorption varies widely between subjects and groups of subjects because of differences in iron status which markedly influence iron assimilation from the gastrointestinal tract. A small dose of isotopically labelled inorganic iron termed the reference dose (3 mg iron as FeSO 4 ) has been used extensively during the past two decades to standardize food iron absorption in human subjects and thereby eliminate the effect of differences in iron status. Recent studies from this laboratory have shown that because of the high variability of absorption from the reference dose, nonheme iron absorption from a standardized meal provides a more reliable means of standardizing absorption from regional diets. We therefore performed initial studies with a rice based meal but we found a relatively high variation in absorption from 2.0 to 4.7% that presumably reflects differences in the phytate content of rice fours. We then undertook the evaluation of meals prepared with farina, a wheat product that is available in most regions of the world. In six different studies from a farina based meal, iron absorption ranged from 3.4 to 6.5%. Nonheme iron absorption from the farina meal when evaluated in separate laboratories extensively engaged in human studies of iron absorption, ranged from 5.1 to 10.8% but when related to the FeSO 4 dose, a more consistent ratio between 0.21 to 0.26 was observed with the exception of one laboratory where a very low absorption of 1.1.% was observed. Percentage absorption from the farina based meal decreased when the iron content of the meal was increased and showed the expected facilitation of absorption when increasing amounts of ascorbic acid were added. By reducing variability and measuring iron absorption from food rather than inorganic iron, we believe that the use of this standard meal will facilitate comparison of iron absorption data obtained in laboratories throughout the world. 4 refs, 2 tabs

Rotational averaging of multiphoton absorption cross sections

Energy Technology Data Exchange (ETDEWEB)

Friese, Daniel H., E-mail: daniel.h.friese@uit.no; Beerepoot, Maarten T. P.; Ruud, Kenneth [Centre for Theoretical and Computational Chemistry, University of Tromsø — The Arctic University of Norway, N-9037 Tromsø (Norway)

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.

A Review: Characteristics of Noise Absorption Material

Science.gov (United States)

Amares, S.; Sujatmika, E.; Hong, T. W.; Durairaj, R.; Hamid, H. S. H. B.

2017-10-01

Noise is always treated as a nuisance to human and even noise pollution appears in the environmental causing discomfort. This also concerns the engineering design that tends to cultivate this noise propagation. Solution such as using material to absorb the sound have been widely used. The fundamental of the sound absorbing propagation, sound absorbing characteristics and its factors are minimally debated. Furthermore, the method in order to pertain sound absorbing related to the sound absorption coefficient is also limited, as many studies only contributes in result basis and very little in literature aspect. This paper revolves in providing better insight on the importance of sound absorption and the materials factors in obtaining the sound absorption coefficient.

Tunable electromagnetically induced absorption based on graphene

Science.gov (United States)

Cao, Maoyong; Wang, Tongling; Zhang, Huiyun; Zhang, Yuping

2018-04-01

In this paper, an electronically induced absorption (EIA) structure based on graphene at the infrared frequency is proposed. A pair of nanorods is coupled to a ring resonator, resulting in electronically induced transparency (EIT), and then, Babinet's principle is applied to transform the EIT structure into an EIA structure. Based on the bright and dark modes of the coupling schemes, the adjustment of the coupling strength between the dark and bright modes can be achieved by changing the asymmetry degree. In addition, the transparency window and the absorption peak can be tuned by changing the Fermi energy of graphene. This graphene-based EIA structure can develop the path in narrow-band filtering and, absorptive switching in the future.

Measurement of Absorption Coefficient of Paraformaldehyde and Metaldehyde with Terahertz Spectroscopy

Science.gov (United States)

Zhang, J.; Xia, T.; Chen, Q.; Sun, Q.; Deng, Y.; Wang, C.

2018-03-01

The characteristic absorption spectra of paraformaldehyde and metaldehyde in the terahertz frequency region are obtained by terahertz time-domain spectroscopy (THz-TDS). In order to reduce the absorption of terahertz (THz) wave by water vapor in the air and the background noise, the measurement system was filled with dry air and the measurements were conducted at the temperature of 24°C. Meanwhile, the humidity was controlled within 10% RH. The THz frequency domain spectra of samples and their references from 0 to 2.5 THz were analyzed via Fourier transform. The refractive index and absorption coefficients of the two aldehydes were calculated by the model formulas. From 0.1 to 2.5 THz, there appear two weak absorption peaks at 1.20 and 1.66 THz in the absorption spectra of paraformaldehyde. Only one distinct absorption peak emerges at 1.83 THz for metaldehyde. There are significant differences between the terahertz absorption coefficients of paraformaldehyde and metaldehyde, which can be used as "fingerprints" to identify these substances. Furthermore, the relationship between the average absorption coefficients and mass concentrations was investigated and the average absorption coefficient-mass concentration diagrams of paraformaldehyde and metaldehyde were shown. For paraformaldehyde, there is a linear relationship between the average absorption coefficient and the natural logarithm of mass concentration. For metaldehyde, there exists a simpler linear relationship between the average absorption coefficient and the mass concentration. Because of the characteristics of THz absorption of paraformaldehyde and metaldehyde, the THz-TDS can be applied to the qualitative and quantitative detection of the two aldehydes to reduce the unpredictable hazards due to these substances.

Process for neptunium analysis by absorption spectrophotometry

International Nuclear Information System (INIS)

Wagner, J.F.

1987-01-01

An aqueous solution of a neptunium compounds is treated by a reagent, preferentially a vanadyl sulfate oxidized by cerium IV ions, to obtain neptunium V by oxidation of neptunium IV and reduction of neptunium VI. The reagent is chosen for a negligible absorption at the wavelength used for neptunium V absorption spectrophotometry for instance 981 nm [fr

Absorption heat pump system

Science.gov (United States)

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.

Vitamin B12 absorption capacity in healthy children

International Nuclear Information System (INIS)

Hjelt, K.; Krasilnikoff, P.A.

1986-01-01

B12 absorption was investigated in 47 healthy children aged 7 months to 15.8 years (median 4.9 years). The patients had either recovered from giardiasis, the post-gastroenteritis syndrome, or had celiac disease in remission (treated with a gluten-free diet). The B12 absorption was measured by a double-isotope technique using 57 CoB12 and 51 CrCl 3 , the latter being the inabsorbable marker. The radiation dose was minimal. The results were presented as fractional absorption of B12 (FAB12). Within the different age groups, the absorption test was performed by means of the following oral amounts of B12: 0- less than 1 year, 0.5 microgram; 1-3 years: 1.7 micrograms, 4-6 years, 2.5 micrograms; 7-10 years; 3.3 micrograms; and 11-15 years, 4.5 micrograms. When using these oral amounts of B12, the medians (and ranges) of FAB12 were found to be: 1-3 years (n = 18), 37% (16-80%); 4-6 years (n = 10), 27% (19-40%); 7-10 years (n = 9), 32% (21-44%); and 11-15 years (n = 8), 27% (19-59%). The FAB12 in two children aged 7 and 11 months was 31% and 32%, respectively. These results may be interpretated as reference values for B12 absorption in children. Further absorption tests were performed in seven children representing the four age groups from 1 to 15 years. When a high oral amount of B12 was given (i.e., three times the saturation dose), the FAB12 ranged from 0 to 20% (median 9%), whereas a low amount (i.e., one-ninth of the saturation dose) produced fractional absorptions from 65 to 82% (median 74%)

Vitamin B12 absorption capacity in healthy children

Energy Technology Data Exchange (ETDEWEB)

Hjelt, K.; Krasilnikoff, P.A.

1986-03-01

B12 absorption was investigated in 47 healthy children aged 7 months to 15.8 years (median 4.9 years). The patients had either recovered from giardiasis, the post-gastroenteritis syndrome, or had celiac disease in remission (treated with a gluten-free diet). The B12 absorption was measured by a double-isotope technique using /sup 57/CoB12 and /sup 51/CrCl/sub 3/, the latter being the inabsorbable marker. The radiation dose was minimal. The results were presented as fractional absorption of B12 (FAB12). Within the different age groups, the absorption test was performed by means of the following oral amounts of B12: 0- less than 1 year, 0.5 microgram; 1-3 years: 1.7 micrograms, 4-6 years, 2.5 micrograms; 7-10 years; 3.3 micrograms; and 11-15 years, 4.5 micrograms. When using these oral amounts of B12, the medians (and ranges) of FAB12 were found to be: 1-3 years (n = 18), 37% (16-80%); 4-6 years (n = 10), 27% (19-40%); 7-10 years (n = 9), 32% (21-44%); and 11-15 years (n = 8), 27% (19-59%). The FAB12 in two children aged 7 and 11 months was 31% and 32%, respectively. These results may be interpretated as reference values for B12 absorption in children. Further absorption tests were performed in seven children representing the four age groups from 1 to 15 years. When a high oral amount of B12 was given (i.e., three times the saturation dose), the FAB12 ranged from 0 to 20% (median 9%), whereas a low amount (i.e., one-ninth of the saturation dose) produced fractional absorptions from 65 to 82% (median 74%).

Paracellular absorption: a bat breaks the mammal paradigm.

Directory of Open Access Journals (Sweden)

Enrique Caviedes-Vidal

Full Text Available Bats tend to have less intestinal tissue than comparably sized nonflying mammals. The corresponding reduction in intestinal volume and hence mass of digesta carried is advantageous because the costs of flight increase with load carried and because take-off and maneuverability are diminished at heavier masses. Water soluble compounds, such as glucose and amino acids, are absorbed in the small intestine mainly via two pathways, the transporter-mediated transcellular and the passive, paracellular pathways. Using the microchiropteran bat Artibeus literatus (mean mass 80.6+/-3.7 g, we tested the predictions that absorption of water-soluble compounds that are not actively transported would be extensive as a compensatory mechanism for relatively less intestinal tissue, and would decline with increasing molecular mass in accord with sieve-like paracellular absorption. Using a standard pharmacokinetic technique, we fed, or injected intraperitoneally the metabolically inert carbohydrates L-rhamnose (molecular mass = 164 Da and cellobiose (molecular mass = 342 Da which are absorbed only by paracellular transport, and 3-O-methyl-D-glucose (3OMD-glucose which is absorbed via both mediated (active and paracellular transport. As predicted, the bioavailability of paracellular probes declined with increasing molecular mass (rhamnose, 90+/-11%; cellobiose, 10+/-3%, n = 8 and was significantly higher in bats than has been reported for laboratory rats and other mammals. In addition, absorption of 3OMD-glucose was high (96+/-11%. We estimated that the bats rely on passive, paracellular absorption for more than 70% of their total glucose absorption, much more than in non-flying mammals. Although possibly compensating for less intestinal tissue, a high intestinal permeability that permits passive absorption might be less selective than a carrier-mediated system for nutrient absorption and might permit toxins to be absorbed from plant and animal material in the

Compressive Behaviour and Energy Absorption of Aluminium Foam Sandwich

Science.gov (United States)

Endut, N. A.; Hazza, M. H. F. Al; Sidek, A. A.; Adesta, E. T. Y.; Ibrahim, N. A.

2018-01-01

Development of materials in automotive industries plays an important role in order to retain the safety, performance and cost. Metal foams are one of the idea to evolve new material in automotive industries since it can absorb energy when it deformed and good for crash management. Recently, new technology had been introduced to replace metallic foam by using aluminium foam sandwich (AFS) due to lightweight and high energy absorption behaviour. Therefore, this paper provides reliable data that can be used to analyze the energy absorption behaviour of aluminium foam sandwich by conducting experimental work which is compression test. Six experiments of the compression test were carried out to analyze the stress-strain relationship in terms of energy absorption behavior. The effects of input variables include varying the thickness of aluminium foam core and aluminium sheets on energy absorption behavior were evaluated comprehensively. Stress-strain relationship curves was used for energy absorption of aluminium foam sandwich calculation. The result highlights that the energy absorption of aluminium foam sandwich increases from 12.74 J to 64.42 J respectively with increasing the foam and skin thickness.

Near-infrared free carrier absorption in heavily doped silicon

International Nuclear Information System (INIS)

Baker-Finch, Simeon C.; McIntosh, Keith R.; Yan, Di; Fong, Kean Chern; Kho, Teng C.

2014-01-01

Free carrier absorption in heavily doped silicon can have a significant impact on devices operating in the infrared. In the near infrared, the free carrier absorption process can compete with band to band absorption processes, thereby reducing the number of available photons to optoelectronic devices such as solar cells. In this work, we fabricate 18 heavily doped regions by phosphorus and boron diffusion into planar polished silicon wafers; the simple sample structure facilitates accurate and precise measurement of the free carrier absorptance. We measure and model reflectance and transmittance dispersion to arrive at a parameterisation for the free carrier absorption coefficient that applies in the wavelength range between 1000 and 1500 nm, and the range of dopant densities between ∼10 18 and 3 × 10 20  cm −3 . Our measurements indicate that previously published parameterisations underestimate the free carrier absorptance in phosphorus diffusions. On the other hand, published parameterisations are generally consistent with our measurements and model for boron diffusions. Our new model is the first to be assigned uncertainty and is well-suited to routine device analysis

Credibility judgments of narratives: language, plausibility, and absorption.

Science.gov (United States)

Nahari, Galit; Glicksohn, Joseph; Nachson, Israel

2010-01-01

Two experiments were conducted in order to find out whether textual features of narratives differentially affect credibility judgments made by judges having different levels of absorption (a disposition associated with rich visual imagination). Participants in both experiments were exposed to a textual narrative and requested to judge whether the narrator actually experienced the event he described in his story. In Experiment 1, the narrative varied in terms of language (literal, figurative) and plausibility (ordinary, anomalous). In Experiment 2, the narrative varied in terms of language only. The participants' perceptions of the plausibility of the story described and the extent to which they were absorbed in reading were measured. The data from both experiments together suggest that the groups applied entirely different criteria in credibility judgments. For high-absorption individuals, their credibility judgment depends on the degree to which the text can be assimilated into their own vivid imagination, whereas for low-absorption individuals it depends mainly on plausibility. That is, high-absorption individuals applied an experiential mental set while judging the credibility of the narrator, whereas low-absorption individuals applied an instrumental mental set. Possible cognitive mechanisms and implications for credibility judgments are discussed.

Development of an Ionic-Liquid Absorption Heat Pump

Energy Technology Data Exchange (ETDEWEB)

Holcomb, Don

2011-03-29

Solar Fueled Products (SFP) is developing an innovative ionic-liquid absorption heat pump (ILAHP). The development of an ILAHP is extremely significant, as it could result in annual savings of more than 190 billion kW h of electrical energy and $19 billion. This absorption cooler uses about 75 percent less electricity than conventional cooling and heating units. The ILAHP also has significant environmental sustainability benefits, due to reduced CO2 emissions. Phase I established the feasibility and showed the economic viability of an ILAHP with these key accomplishments: • Used the breakthrough capabilities provided by ionic liquids which overcome the key difficulties of the common absorption coolers. • Showed that the theoretical thermodynamic performance of an ILAHP is similar to existing absorption-cooling systems. • Established that the half-effect absorption cycle reduces the peak generator temperature, improving collector efficiency and reducing collector area. • Component testing demonstrated that the most critical components, absorber and generator, operate well with conventional heat exchangers. • Showed the economic viability of an ILAHP. The significant energy savings, sustainability benefits, and economic viability are compelling reasons to continue the ILAHP development.

Exciton absorption of entangled photons in semiconductor quantum wells

Science.gov (United States)

Rodriguez, Ferney; Guzman, David; Salazar, Luis; Quiroga, Luis; Condensed Matter Physics Group Team

2013-03-01

The dependence of the excitonic two-photon absorption on the quantum correlations (entanglement) of exciting biphotons by a semiconductor quantum well is studied. We show that entangled photon absorption can display very unusual features depending on space-time-polarization biphoton parameters and absorber density of states for both bound exciton states as well as for unbound electron-hole pairs. We report on the connection between biphoton entanglement, as quantified by the Schmidt number, and absorption by a semiconductor quantum well. Comparison between frequency-anti-correlated, unentangled and frequency-correlated biphoton absorption is addressed. We found that exciton oscillator strengths are highly increased when photons arrive almost simultaneously in an entangled state. Two-photon-absorption becomes a highly sensitive probe of photon quantum correlations when narrow semiconductor quantum wells are used as two-photon absorbers. Research funds from Facultad de Ciencias, Universidad de los Andes

Optical absorption of hyperbolic metamaterial with stochastic surfaces

DEFF Research Database (Denmark)

Liu, Jingjing; Naik, Gururaj V.; Ishii, Satoshi

2014-01-01

We investigate the absorption properties of planar hyperbolic metamaterials (HMMs) consisting of metal-dielectric multilayers, which support propagating plane waves with anomalously large wavevectors and high photonic-density-of-states over a broad bandwidth. An interface formed by depositing...... indium-tin-oxide nanoparticles on an HMM surface scatters light into the high-k propagating modes of the metamaterial and reduces reflection. We compare the reflection and absorption from an HMM with the nanoparticle cover layer versus those of a metal film with the same thickness also covered...... with the nanoparticles. It is predicted that the super absorption properties of HMM show up when exceedingly large amounts of high-k modes are excited by strong plasmonic resonances. In the case that the coupling interface is formed by non-resonance scatterers, there is almost the same enhancement in the absorption...

Possibilities of testing capillary absorption on microcores

Directory of Open Access Journals (Sweden)

Čeh Arpad

2016-01-01

Full Text Available During inspection of reinforced concrete structures from the aspect of durability evaluation of concrete, the present methods generally use the test results obtained by the sophisticated and expensive equipment, which are usually not universal purpose, ie. they can be used only for one segment of durability evaluation of the concrete. This way any additional information about the condition of concrete is valuable, especially if it is not require an additional testing with special equipment. Tests of concrete and reinforced concrete with microcore drilling is considered to be a semi- destructive method, which slightly damages the structure itself, and it is primarily used for testing carbonation, density and absorption of concrete. The paper presents the results of capillary absorption according to SRPS EN 480-5 on standard-size samples and on the microcores extracted from cube form samples with edge length of 20 cm. In the article the testing results of penetration of water under pressure are also presented on the same samples, on which we previously gained microcores. These tests were carried out on with concrete mixtures designed for the most demanding exposure classes according to EN 206-1 and using a variety of additives that are known to affect the structure of pores and consequently also the durability of a hardened concrete.

Effects of iron, tin, and copper on zinc absorption in humans

International Nuclear Information System (INIS)

Valberg, L.S.; Flanagan, P.R.; Chamberlain, M.J.

1984-01-01

Zinc absorption as measured by body retention of [65Zn]zinc chloride or a turkey test meal extrinsically labeled with 65Zn was determined in human subjects by whole body counting after 7 days. Average 65Zn absorption from zinc chloride in persons with a high iron-absorbing capacity was similar to persons with a low capacity to absorb iron. Inorganic iron, 920 mumol (51 mg), or HB iron, 480 mumol (26 mg), inhibited 65Zn absorption from 92 mumol (6 mg) of zinc chloride. When 610 mumol of iron (34 mg) was added to a turkey test meal containing 61 mumol of zinc (4 mg), 65Zn absorption was not inhibited. Tin, 306 mumol (36 mg), given with zinc chloride or turkey test meals (61 mumol, 4 mg, of Zn) significantly reduced 65Zn absorption. Copper, 79 mumol (5 mg), had no significant effect on the 65Zn absorption from 7.9 mumol (0.5 mg) of zinc chloride. In summary, the capacity to absorb iron did not influence 65Zn absorption, but both inorganic iron and heme-iron inhibited 65Zn absorption from zinc chloride. Inorganic iron had no effect, however, on 65Zn absorption from the turkey test meal. Tin in a large dose also inhibited 65Zn absorption from both zinc chloride and the turkey test meal

Narrow absorption lines complex I: one form of broad absorption line

Science.gov (United States)

Lu, Wei-Jian; Lin, Ying-Ru

2018-03-01

We discover that some of the broad absorption lines (BALs) are actually a complex of narrow absorption lines (NALs). As a pilot study of this type of BAL, we show this discovery through a typical example in this paper. Utilizing the two-epoch observations of J002710.06-094435.3 (hereafter J0027-0944) from the Sloan Digital Sky Survey (SDSS), we find that each of the C IV and Si IV BAL troughs contains at least four NAL doublets. By resolving the Si IV BAL into multiple NALs, we present the following main results and conclusions. First, all these NALs show coordinated variations between the two-epoch SDSS observations, suggesting that they all originate in the quasar outflow, and that their variations are due to global changes in the ionization condition of the absorbing gas. Secondly, a BAL consisting of a number of NAL components indicates that this type of BAL is basically the same as the intrinsic NAL, which tends to support the inclination model rather than the evolution model. Thirdly, although both the C IV and Si IV BALs originate from the same clumpy substructures of the outflow, they show different profile shapes: multiple absorption troughs for the Si IV BAL in a wider velocity range, while P-Cygni for the C IV BAL in a narrower velocity range. This can be interpreted by the substantial differences in fine structure and oscillator strength between the Si IVλλ1393, 1402 and C IVλλ1548, 1551 doublets. Based on the above conclusions, we consider that the decomposition of a BAL into NALs can serve as a way to resolve the clumpy structure for outflows, and it can be used to learn more about characteristics of the clumpy structure and to test the outflow model, when utilizing high-resolution spectra and photoionization model.

Cavity ring-down spectroscopy (CRDS) system for measuring atmospheric mercury using differential absorption

Science.gov (United States)

Pierce, A.; Obrist, D.; Moosmuller, H.; Moore, C.

2012-04-01

Atmospheric elemental mercury (Hg0) is a globally pervasive element that can be transported and deposited to remote ecosystems where it poses — particularly in its methylated form — harm to many organisms including humans. Current techniques for measurement of atmospheric Hg0 require several liters of sample air and several minutes for each analysis. Fast-response (i.e., 1 second or faster) measurements would improve our ability to understand and track chemical cycling of mercury in the atmosphere, including high frequency Hg0 fluctuations, sources and sinks, and chemical transformation processes. We present theory, design, challenges, and current results of our new prototype sensor based on cavity ring-down spectroscopy (CRDS) for fast-response measurement of Hg0 mass concentrations. CRDS is a direct absorption technique that implements path-lengths of multiple kilometers in a compact absorption cell using high-reflectivity mirrors, thereby improving sensitivity and reducing sample volume compared to conventional absorption spectroscopy. Our sensor includes a frequency-doubled, dye-laser emitting laser pulses tunable from 215 to 280 nm, pumped by a Q-switched, frequency tripled Nd:YAG laser with a pulse repetition rate of 50 Hz. We present how we successfully perform automated wavelength locking and stabilization of the laser to the peak Hg0 absorption line at 253.65 nm using an external isotopically-enriched mercury (202Hg0) cell. An emphasis of this presentation will be on the implementation of differential absorption measurement whereby measurements are alternated between the peak Hg0 absorption wavelength and a nearby wavelength "off" the absorption line. This can be achieved using a piezo electric tuning element that allows for pulse-by-pulse tuning and detuning of the laser "online" and "offline" of the Hg absorption line, and thereby allows for continuous correction of baseline extinction losses. Unexpected challenges with this approach included

Intrinsic defect oriented visible region absorption in zinc oxide films

Science.gov (United States)

Rakhesh, V.; Shankar, Balakrishnan

2018-05-01

Zinc Oxide films were deposited on the glass substrate using vacuum arc sputtering technology. Films were prepared in oxygen ambience for 10mA and 15 mA deposition current separately. The UV-Visible spectroscopy of the samples showed that both samples possess sharp absorption near 3.5eV which is the characteristic band gap absorption energy of ZnO films. The absorption coefficient were calculated for the samples and the (αℎϑ)2 vs energy plot is drawn. The plot suggested that in addition to the sharp band edge absorption, the sample prepared at 10mA deposition current showed sharp absorption edge near 1.51eV and that at 15 mA showed absorption edge near 1.47eV. This refers to the presence of an intrinsic defect level which is likely to be deep in the band gap.

Water vapor absorption of carbon dioxide laser radiation

Science.gov (United States)

Shumate, M. S.; Menzies, R. T.; Margolis, J. S.; Rosengren, L.-G.

1976-01-01

An optoacoustic detector or spectrophone has been used to perform detailed measurements of the absorptivity of mixtures of water vapor in air. A (C-12) (O-16)2 laser was used as the source, and measurements were made at forty-nine different wavelengths from 9.2 to 10.7 microns. The details of the optoacoustic detector and its calibration are presented, along with a discussion of its performance characteristics. The results of the measurements of water vapor absorption show that the continuum absorption in the wavelength range covered is 5-10% lower than previous measurements.

Exciton molecule in semiconductors by two-photon absorption

International Nuclear Information System (INIS)

Arya, K.; Hassan, A.R.

1976-07-01

Direct creation of bi-exciton states by two-photon absorption in direct gap semiconductors is investigated theoretically. A numerical application to the case of CuCl shows that the two-photon absorption coefficient for bi-excitonic transitions is larger than that for two-photon interband transitions by three orders of magnitude. It becomes comparable to that for one-photon excitonic transitions for available laser intensities. The main contribution to this enhancement of the absorption coefficient for the transitions to the bi-exciton states is found to be from the resonance effect

Photon absorption of calcium phosphate-based dental biomaterials

International Nuclear Information System (INIS)

Singh, V. P.; Badiger, N. M.; Tekin, H. O.; Kara, U.; Vega C, H. R.; Fernandes Z, M. A.

2017-10-01

Effective atomic number and mass energy absorption buildup factors for four calcium phosphate-based biomaterials used in dental treatments were calculated for 0.015 to 15 MeV photons. The mass energy absorption coefficients were calculated for 0.5 to 40 mean free paths of photons. In the energy region important for dental radiology the Zeff for all studied biomaterials are larger in comparison to larger energies. In x-rays for dental radiology and the energy absorption buildup factors are low, however CbMDI bio material shows a resonance at 80 keV. (Author)

Mass: Fortran program for calculating mass-absorption coefficients

International Nuclear Information System (INIS)

Nielsen, Aa.; Svane Petersen, T.

1980-01-01

Determinations of mass-absorption coefficients in the x-ray analysis of trace elements are an important and time consuming part of the arithmetic calculation. In the course of time different metods have been used. The program MASS calculates the mass-absorption coefficients from a given major element analysis at the x-ray wavelengths normally used in trace element determinations and lists the chemical analysis and the mass-absorption coefficients. The program is coded in FORTRAN IV, and is operational on the IBM 370/165 computer, on the UNIVAC 1110 and on PDP 11/05. (author)

Development and comparison of different advanced absorption cycles

Energy Technology Data Exchange (ETDEWEB)

Arh, S; Gaspersic, B [Faculty of Mechanical Engineering, Ljubjana (YU)

1990-01-01

A method for the calculation of the coefficient of performance for any absorption cycle is described. This method was used for the evaluation of different advanced absorption cycles working between four temperature and two or three pressure levels. Similar cycles were compared in the same temperature range with regard to the coefficient of performance, exergy efficiency and two working fluid pairs, NH{sub 3}-H{sub 2}O and H{sub 2}O-LiBr. Cycles and numerical results are presented and a computer-aided absorption cycle development system described. (author).

Pavement sound absorption measurements in the U.S.

Science.gov (United States)

2012-08-19

In the U.S., the topic of pavement sound absorption in regard to tire-pavement noise has shown increased interest and research over the last several years. Four types of pavement sound absorption measurements with various applications are discussed: ...

Absorption by Spinning Dust: A Contaminant for High-redshift 21 cm Observations

Science.gov (United States)

Draine, B. T.; Miralda-Escudé, Jordi

2018-05-01

Spinning dust grains in front of the bright Galactic synchrotron background can produce a weak absorption signal that could affect measurements of high-redshift 21 cm absorption. At frequencies near 80 MHz where the Experiment to Detect the Global EoR Signature (EDGES) has reported 21 cm absorption at z≈ 17, absorption could be produced by interstellar nanoparticles with radii a≈ 50 \\mathringA in the cold interstellar medium (ISM), with rotational temperature T ≈ 50 K. Atmospheric aerosols could contribute additional absorption. The strength of the absorption depends on the abundance of such grains and on their dipole moments, which are uncertain. The breadth of the absorption spectrum of spinning dust limits its possible impact on measurement of a relatively narrow 21 cm absorption feature.

Parameter study of self-absorption effects in Total Reflection X-ray Fluorescence-X-ray Absorption Near Edge Structure analysis of arsenic

International Nuclear Information System (INIS)

Meirer, F.; Pepponi, G.; Streli, C.; Wobrauschek, P.; Kregsamer, P.; Zoeger, N.; Falkenberg, G.

2008-01-01

Total reflection X-ray Fluorescence (TXRF) analysis in combination with X-ray Absorption Near Edge Structure (XANES) analysis is a powerful method to perform chemical speciation studies at trace element levels. However, when measuring samples with higher concentrations and in particular standards, damping of the oscillations is observed. In this study the influence of self-absorption effects on TXRF-XANES measurements was investigated by comparing measurements with theoretical calculations. As(V) standard solutions were prepared at various concentrations and dried on flat substrates. The measurements showed a correlation between the damping of the oscillations and the As mass deposited. A Monte-Carlo simulation was developed using data of the samples shapes obtained from confocal white light microscopy. The results showed good agreement with the measurements; they confirmed that the key parameters are the density of the investigated atom in the dried residues and the shape of the residue, parameters that combined define the total mass crossed by a certain portion of the incident beam. The study presents a simple approach for an a priori evaluation of the self-absorption in TXRF X-ray absorption studies. The consequences for Extended X-ray Absorption Fine Structure (EXAFS) and XANES measurements under grazing incidence conditions are discussed, leading to the conclusion that the damping of the oscillations seems to make EXAFS of concentrated samples non feasible. For XANES 'fingerprint' analysis samples should be prepared with a deposited mass and sample shape leading to an acceptable absorption for the actual investigation

21 CFR 862.2850 - Atomic absorption spectrophotometer for clinical use.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Atomic absorption spectrophotometer for clinical... Laboratory Instruments § 862.2850 Atomic absorption spectrophotometer for clinical use. (a) Identification. An atomic absorption spectrophotometer for clinical use is a device intended to identify and measure...

Gastrointestinal drug absorption in rats exposed to 60Co γ-radiation

International Nuclear Information System (INIS)

Brady, M.E.

1976-01-01

Following exposure of the gastrointestinal (GI) tract to ionizing radiation, its structure and function are altered for several days. Such alterations may affect the bioavailability of orally administered drugs. The potential mechanisms by which radiation may affect drug absorption were explored by studying the absorption of four test drugs, sulfanilamide, bretylium, sulfisoxazole acetyl, and riboflavin, in rats that were exposed to 850 R cobalt-60 gamma-radiation or sham irradiated. In one series of experiments, the drugs were administered orally and the amount of drug excreted in urine was used as a measure of the extent of their absorption. Cumulative urinary excretion of the drugs was shown to be a valid measure of absorption since it was not affected by radiation after intravenous administration of the drugs. At one day post-irradiation, the extent of absorption of sulfanilamide and bretylium was not affected by radiation but the absorption of sulfisoxazole acetyl and riboflavin was increased. At five days post-irradiation, there was no detectable difference between irradiated and control animals in the extent of absorption of the drugs. The fraction of sulfanilamide excreted in the urine as 4 N-conjugate was increased at one day post-irradiation. The increased excretion of metabolite appeared to result from metabolism of the drug by gut flora prior to absorption. This study shows that radiation-induced alterations in the absorption of orally administered drugs are due primarily to slowed gastric emptying. In general, slowed gastric emptying causes the rate of drug absorption to decline. The extent of absorption of drugs that are normally well absorbed is not affected by radiation while the extent of absorption of drugs that normally are absorbed poorly may be increased after irradiation of the GI tract

Factors affecting the absorption and excretion of lead in the rat

International Nuclear Information System (INIS)

Conrad, M.E.; Barton, J.C.

1978-01-01

A reliable method for studying lead absorption and excretion in rats is described. Lead absorption occurs primarily in the duodenum where lead enters the epithelial mucosal cells. There is a relative mucosal block for lead with increasing intraluminal doses. Certain substances which bind lead and increase its solubility enhance its absorption. Iron, zinc, and calcium decrease the absorption of lead without affecting its solubility, probably by competing for shared absorptive receptors in the intestinal mucosa. The total body burden of lead does not affect lead absorption. Thus, lead does not have a feedback mechanism which limits absorption. Lead absorption is increased during rapid periods of growth and in iron-deficient animals. It is diminished with starvation and in iron-overloaded animals. The excretion and kinetics of tracer doses of radiolead were quantified. Erythrocytes seem to serve an important role in transport. Excretion occurs in urine and stool. Bile is an important route of excretion in the gut. Although most of a tracer dose is rapidly excreted, the excretory process is limited permitting lead accumulation primarily in bone

Anomalous water absorption in porous materials

CERN Document Server

Lockington, D A

2003-01-01

The absorption of fluid by unsaturated, rigid porous materials may be characterized by the sorptivity. This is a simple parameter to determine and is increasingly being used as a measure of a material's resistance to exposure to fluids (especially moisture and reactive solutes) in aggressive environments. The complete isothermal absorption process is described by a nonlinear diffusion equation, with the hydraulic diffusivity being a strongly nonlinear function of the degree of saturation of the material. This diffusivity can be estimated from the sorptivity test. In a typical test the cumulative absorption is proportional to the square root of time. However, a number of researchers have observed deviation from this behaviour when the infiltrating fluid is water and there is some potential for chemo-mechanical interaction with the material. In that case the current interpretation of the test and estimation of the hydraulic diffusivity is no longer appropriate. Kuentz and Lavallee (2001) discuss the anomalous b...

Gastrointestinal absorption of soluble uranium from drinking water. Published paper

International Nuclear Information System (INIS)

Wrenn, M.E.; Singh, N.P.; Ruth, H.; Burleigh, D.

1988-04-01

This manuscript describes results of an experiment to determine the gastrointestinal absorption of uranium from drinking water in 12 health adults. Most of the uranium ingested was excreted in feces in the first 2 days following ingestion of the water. The absorption was the same for (234)U and (238)U for each subject. Absorption varied among subjects from -0.02% to 2.6%, with a mean of 0.6%. Low absorption may be due to concurrent ingestion of food

Control of one- and two-photon absorption in a four-level atomic system by changing the amplitude and phase of a driving microwave field

International Nuclear Information System (INIS)

Hou, B P; Wang, S J; Yu, W L; Sun, W L

2005-01-01

We consider the one- and two-photon absorption spectra of a four-level Y-type atom with the two highest lying levels driven by a microwave field. We found that in the one-photon absorption case, the microwave field can lead to the probe gain, and the absorption and gain spectral structures depend strongly on the microwave field amplitude. For the two-photon absorption case, the strong microwave field can enhance the absorption. When the microwave field amplitude is reduced to a certain value, the single absorption peak in the two-photon spectrum changes into a structure of two-peak structure with different magnitudes. Moreover, the one- and two-photon absorption spectra can be modulated by the phase of the microwave field which produces a closed-loop configuration. Finally, we use the analytic solutions in terms of dressed-state basis to explain the results from our numerical calculation

Cimetidine absorption in humans during sucralfate coadministration.

OpenAIRE

D'Angio, R; Mayersohn, M; Conrad, K A; Bliss, M

1986-01-01

Cimetidine absorption after a single 300 mg oral dose was evaluated in six normal subjects in the absence or presence of sucralfate. Sucralfate was ingested four times a day for 2 days prior to and for two additional doses on the day of cimetidine ingestion. Sucralfate coadministration had no statistically significant influence on the rate or extent of cimetidine absorption.

Improvement of intestinal absorption of forsythoside A in weeping forsythia extract by various absorption enhancers based on tight junctions.

Science.gov (United States)

Zhou, Wei; Qin, Kun Ming; Shan, Jin Jun; Ju, Wen Zheng; Liu, Shi Jia; Cai, Bao Chang; Di, Liu Qing

2012-12-15

Forsythoside A (FTA), one of the main active ingredients in weeping forsythia extract, possesses strong antibacterial, antioxidant and antiviral effects, and its content was about 8% of totally, higher largely than that of other ingredients, but the absolute bioavailability orally was approximately 0.5%, which is significant low influencing clinical efficacies of its oral preparations. In the present study, in vitro Caco-2 cell, in situ single-pass intestinal perfusion and in vivo pharmacokinetics study were performed to investigate the effects of absorption enhancers based on tight junctions: sodium caprate and water-soluble chitosan on the intestinal absorption of FTA, and the eventual mucosal epithelial damage resulted from absorption enhancers was evaluated by MTT test, measurement of total amount of protein and the activity of LDH and morphology observation, respectively. The pharmacological effects such as antioxidant activity improvement by absorption enhancers were verified by PC12 cell damage inhibition rate after H₂O₂ insults. The observations from in vitro Caco-2 cell showed that the absorption of FTA in weeping forsythia extract could be improved by absorption enhancers. Meanwhile, the absorption enhancing effect of water-soluble chitosan may be almost saturable up to 0.0032% (w/v), and sodium caprate at concentrations up to 0.64 mg/ml was safe for the Caco-2 cells, but water-soluble chitosan at different concentrations was all safe for these cells. The observations from single-pass intestinal perfusion in situ model showed that duodenum, jejunum, ileum and colon showed significantly concentration-dependent increase in P(eff)-value, and that P(eff)-value in the ileum and colon groups, where sodium caprate was added, was higher than that of duodenum and jejunum groups, but P(eff)-value in the jejunum group was higher than that of duodenum, ileum and colon groups where water-soluble chitosan was added. Intestinal mucosal toxicity studies showed no

Enhancing effect of bile salts on gastrointestinal absorption of insulin ...

African Journals Online (AJOL)

Purpose: To investigate the effect of co-administration of two absorption enhancing bile alts, sodium glycocholate (NaGc) and sodium salicylate (NaSal), on insulin absorption via intestinal targeted delivery system. Methods: Insulin (10 IU/kg), associated with and without absorption enhancers (5 % enhancer solution of ...

Protein Hydrolysates as Promoters of Non-Haem Iron Absorption

Science.gov (United States)

Li, Yanan; Jiang, Han; Huang, Guangrong

2017-01-01

Iron (Fe) is an essential micronutrient for human growth and health. Organic iron is an excellent iron supplement due to its bioavailability. Both amino acids and peptides improve iron bioavailability and absorption and are therefore valuable components of iron supplements. This review focuses on protein hydrolysates as potential promoters of iron absorption. The ability of protein hydrolysates to chelate iron is thought to be a key attribute for the promotion of iron absorption. Iron-chelatable protein hydrolysates are categorized by their absorption forms: amino acids, di- and tri-peptides and polypeptides. Their structural characteristics, including their size and amino acid sequence, as well as the presence of special amino acids, influence their iron chelation abilities and bioavailabilities. Protein hydrolysates promote iron absorption by keeping iron soluble, reducing ferric iron to ferrous iron, and promoting transport across cell membranes into the gut. We also discuss the use and relative merits of protein hydrolysates as iron supplements. PMID:28617327

Absorption and emission spectroscopic characterisation of 8-amino-riboflavin

Energy Technology Data Exchange (ETDEWEB)

Tyagi, A.; Zirak, P. [Institut II - Experimentelle und Angewandte Physik, Universitaet Regensburg, Universitaetsstrasse 31, D-93053 Regensburg (Germany); Penzkofer, A., E-mail: alfons.penzkofer@physik.uni-regensburg.de [Institut II - Experimentelle und Angewandte Physik, Universitaet Regensburg, Universitaetsstrasse 31, D-93053 Regensburg (Germany); Mathes, T.; Hegemann, P. [Institut fuer Biologie/Experimentelle Biophysik, Humboldt Universitaet zu Berlin, Invalidenstrasse 42, D-10115 Berlin (Germany); Mack, M. [Institut fuer Technische Mikrobiologie, Hochschule Mannheim, Paul-Wittsack-Str. 10, D-68163 Mannheim (Germany); Ghisla, S. [Universitaet Konstanz, Fakultaet fuer Biologie, P.O. Box 5560-M644, D-78457 Konstanz (Germany)

2009-10-16

The flavin dye 8-amino-8-demethyl-D-riboflavin (AF) in the solvents water, DMSO, methanol, and chloroform/DMSO was studied by absorption and fluorescence spectroscopy. The first absorption band is red-shifted compared to riboflavin, and blue-shifted compared to roseoflavin (8-dimethylamino-8-demethyl-D-riboflavin). The fluorescence quantum yield of AF in the studied solvents varies between 20% and 50%. The fluorescence lifetimes were found to be in the 2-5 ns range. AF is well soluble in DMSO, weakly soluble in water and methanol, and practically insoluble in chloroform. The limited solubility causes AF aggregation, which was seen in differences between measured absorption spectra and fluorescence excitation spectra. Light scattering in the dye absorption region is discussed and approximate absorption cross-section spectra are determined from the combined measurement of transmission and fluorescence excitation spectra. The photo-stability of AF was studied by prolonged light exposure. The photo-degradation routes of AF are discussed.

Absorption and emission spectroscopic characterisation of 8-amino-riboflavin

Science.gov (United States)

Tyagi, A.; Zirak, P.; Penzkofer, A.; Mathes, T.; Hegemann, P.; Mack, M.; Ghisla, S.

2009-10-01

The flavin dye 8-amino-8-demethyl- D-riboflavin (AF) in the solvents water, DMSO, methanol, and chloroform/DMSO was studied by absorption and fluorescence spectroscopy. The first absorption band is red-shifted compared to riboflavin, and blue-shifted compared to roseoflavin (8-dimethylamino-8-demethyl-D-riboflavin). The fluorescence quantum yield of AF in the studied solvents varies between 20% and 50%. The fluorescence lifetimes were found to be in the 2-5 ns range. AF is well soluble in DMSO, weakly soluble in water and methanol, and practically insoluble in chloroform. The limited solubility causes AF aggregation, which was seen in differences between measured absorption spectra and fluorescence excitation spectra. Light scattering in the dye absorption region is discussed and approximate absorption cross-section spectra are determined from the combined measurement of transmission and fluorescence excitation spectra. The photo-stability of AF was studied by prolonged light exposure. The photo-degradation routes of AF are discussed.

Absorption and emission spectroscopic characterisation of 8-amino-riboflavin

International Nuclear Information System (INIS)

Tyagi, A.; Zirak, P.; Penzkofer, A.; Mathes, T.; Hegemann, P.; Mack, M.; Ghisla, S.

2009-01-01

The flavin dye 8-amino-8-demethyl-D-riboflavin (AF) in the solvents water, DMSO, methanol, and chloroform/DMSO was studied by absorption and fluorescence spectroscopy. The first absorption band is red-shifted compared to riboflavin, and blue-shifted compared to roseoflavin (8-dimethylamino-8-demethyl-D-riboflavin). The fluorescence quantum yield of AF in the studied solvents varies between 20% and 50%. The fluorescence lifetimes were found to be in the 2-5 ns range. AF is well soluble in DMSO, weakly soluble in water and methanol, and practically insoluble in chloroform. The limited solubility causes AF aggregation, which was seen in differences between measured absorption spectra and fluorescence excitation spectra. Light scattering in the dye absorption region is discussed and approximate absorption cross-section spectra are determined from the combined measurement of transmission and fluorescence excitation spectra. The photo-stability of AF was studied by prolonged light exposure. The photo-degradation routes of AF are discussed.

Protein Hydrolysates as Promoters of Non-Haem Iron Absorption

Directory of Open Access Journals (Sweden)

Yanan Li

2017-06-01

Full Text Available Iron (Fe is an essential micronutrient for human growth and health. Organic iron is an excellent iron supplement due to its bioavailability. Both amino acids and peptides improve iron bioavailability and absorption and are therefore valuable components of iron supplements. This review focuses on protein hydrolysates as potential promoters of iron absorption. The ability of protein hydrolysates to chelate iron is thought to be a key attribute for the promotion of iron absorption. Iron-chelatable protein hydrolysates are categorized by their absorption forms: amino acids, di- and tri-peptides and polypeptides. Their structural characteristics, including their size and amino acid sequence, as well as the presence of special amino acids, influence their iron chelation abilities and bioavailabilities. Protein hydrolysates promote iron absorption by keeping iron soluble, reducing ferric iron to ferrous iron, and promoting transport across cell membranes into the gut. We also discuss the use and relative merits of protein hydrolysates as iron supplements.

Enhanced electroabsorption in strained-layer InxGa1-xAs-InP quantum wells via absorption edge merging

International Nuclear Information System (INIS)

Gomatam, B.N.; Anderson, N.G.

1990-01-01

Optoelectronic modulators are useful for optical communications, optical computing and other applications which require the electronic control of guided light. Considerable research has recently been devoted to multiple quantum well (MQW) modulators which use an electroabsorption effect unique to quantum wells: the quantum confined Stark effect (QCSE). Voltage controlled optical modulation can be achieved by Stark-shifting the absorption edge above and below the incident photon energy. This paper reports that, to obtain increased optical on-off ratios at decreased drive voltages, the authors are investigating a novel approach which exploits characteristics of MQWs under biaxial tension. The light hole band edge lies at a higher energy than the heavy hole band edge in these structures, which is opposite the case for unstrained or biaxially compressed structures. Since the absorption edge associated with the heavy holes decreases more rapidly with applied field than that for the light holes, merging of the two edges can be expected at some value of the applied field. This effect here called absorption edge merging (AEM), can be expected to give rise to a significant improvement in modulator design. We have theoretically investigated the AEM effect in In x Ga 1-x As/InP quantum well structures with x x Ga 1-x As quantum wells are under tension in such structures, hence the required light hole up band configuration can be achieved

Noble gas absorption process

International Nuclear Information System (INIS)

Thomas, J.W.

1975-01-01

A method of removing a noble gas from air comprising the use of activated carbon filters in stages in which absorption and desorption steps in succession are conducted in order to increase the capacity of the filters is described. (U.S.)

UV absorption by cerium oxide nanoparticles/epoxy composite thin films

International Nuclear Information System (INIS)

Dao, Ngoc Nhiem; Luu, Minh Dai; Nguyen, Quang Khuyen; Kim, Byung Sun

2011-01-01

Cerium oxide (CeO 2 ) nanoparticles have been used to modify properties of an epoxy matrix in order to improve the ultra-violet (UV) absorption property of epoxy thin films. The interdependence of mechanical properties, UV absorption property and the dispersed concentration of CeO 2 nanoparticles was investigated. Results showed that, by increasing the dispersed concentration of CeO 2 nanoparticles up to 3 wt%, tensile modulus increases while two other mechanical properties, namely tensile strength and elongation, decrease. The UV absorption peak and the absorption edges of the studied thin films were observed in the UV-Vis absorption spectra. By incorporating CeO 2 nanoparticles into the epoxy matrix, an absorption peak appears at around 318 nm in UV-Vis spectra with increasing CeO 2 concentration from 0.1 to 1.0 wt%. Scanning electron microscopy (SEM) images revealed that a good dispersion of nanoparticles in the epoxy matrix by an ultrasonic method was achieved

Synthesis, characterization and microwave absorption of carbon-coated Cu nanocapsules

Energy Technology Data Exchange (ETDEWEB)

Sun, Yuping [Center for Engineering Practice and Innovation Education, Anhui University of Technology, Maanshan, (China); Feng, Chao; Liu, Xianguo; Jin, Chuangui, E-mail: liuxianguohugh@gmail.com [School of Materials Science and Engineering, Anhui University of Technology, Maanshan (China); Or, Siu Wing [Department of Electrical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, (Hong Kong)

2014-03-15

The microstructure and microwave absorption of carbon-coated Cu nanocapsules have been investigated. Carbon-coated Cu nanocapsules have been synthesized by an arc-discharge method. The paraffin-Cu/C nanocapsules composite shows excellent electromagnetic (EM) absorption properties. An optimal reflection loss (RL) value of –40.0 dB is reached at 10.52 GHz for a layer 1.9 mm thickness. RL exceeding –20 dB can be realized in any interval within the 1-18 GHz range by choosing an appropriate thickness of the absorbent layer between 1.1 and 10.0 mm. Theoretical simulation for the microwave absorption using the transmission line theory agrees reasonably well with the experimental results. The EM-wave absorption properties of nanocapsules materials are illustrated by means of an absorption-tube-map. The carbon-coated Cu nano capsule is an attractive candidate for EM-wave absorption, which significantly enriches the family of EM-wave nano absorbents. (author)

Standard Practice for Evaluating Solar Absorptive Materials for Thermal Applications

CERN Document Server

American Society for Testing and Materials. Philadelphia

2007-01-01

1.1 This practice covers a testing methodology for evaluating absorptive materials used in flat plate or concentrating collectors, with concentrating ratios not to exceed five, for solar thermal applications. This practice is not intended to be used for the evaluation of absorptive surfaces that are (1) used in direct contact with, or suspended in, a heat-transfer liquid, (that is, trickle collectors, direct absorption fluids, etc.); (2) used in evacuated collectors; or (3) used in collectors without cover plate(s). 1.2 Test methods included in this practice are property measurement tests and aging tests. Property measurement tests provide for the determination of various properties of absorptive materials, for example, absorptance, emittance, and appearance. Aging tests provide for exposure of absorptive materials to environments that may induce changes in the properties of test specimens. Measuring properties before and after an aging test provides a means of determining the effect of the exposure. 1.3 Th...

Water absorption and mechanical properties of water-swellable natural rubber

Directory of Open Access Journals (Sweden)

Diew Saijun

2009-11-01

Full Text Available Water-swellable rubber (WSR was prepared by blending superabsorbent polymer (SAP of crosslinked poly(acrylamide-co-sodium acrylate with natural rubber in latex condition. The crosslinked poly(acrylamide-co-sodium acrylate was first prepared by inverse suspension polymerization from acrylamide and sodium acrylate monomers with potassiumpersulfate initiator and N,N-methylenebisacrylamide crosslinker. The reaction was carried out at 60oC for 40 mins. Water absorption properties, such as the degree of water absorption, water absorption rate, degree of weight loss, and mechanicalproperties of WSR were then investigated. It was found that the degree of water absorption, water absorption rate, and thedegree of weight loss increased, while tensile strength and elongation at break decreased with increasing quantity of SAP inthe blends. However, the degree of water absorption, degree of weight loss, and elongation at break decreased, but tensilestrength increased with increasing quantity of the N-tert-butyl-2-benzothiazyl sulphenamide (TBBS accelerator used in thecompounds formulation.

Reliability of graphite furnace atomic absorption spectrometry as ...

African Journals Online (AJOL)

Purpose: To evaluate the comparative efficiency of graphite furnace atomic absorption spectrometry (GFAAS) and hydride generation atomic absorption spectrometry (HGAAS) for trace analysis of arsenic (As) in natural herbal products (NHPs). Method: Arsenic analysis in natural herbal products and standard reference ...

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

Science.gov (United States)

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.

Effects of divalent amino acids on iron absorption

International Nuclear Information System (INIS)

Christensen, J.M.; Ghannam, M.; Ayres, J.W.

1984-01-01

Solutions of each of 10 amino acids or ascorbic acid were mixed with iron and orally administered to rats. Iron was absorbed to a statistically significantly greater extent when mixed with asparagine, glycine, serine, or ascorbic acid as compared with a control solution of iron. The largest effects were for asparagine and glycine, which also increased iron absorption to a significantly greater extent than did serine or ascorbic acid. No statistically significant increase in iron absorption occurred when any of the other amino acids was mixed with iron. The extent of iron absorption from each test solution, as measured by area under the concentration of iron-59 in the blood-time curve (r2 . 0.0002), and the initial rate of iron absorption for each test solution (r2 . 0.01) showed no correlation with the stability constant of the amino acid-iron complex

Absorption spectra of trapped holes in anatase TiO2

DEFF Research Database (Denmark)

Zawadzki, Pawel

2013-01-01

absorption spectroscopy (TAS), but the understanding of the optical absorption due to trapped carriers in TiO2 is incomplete. On the basis of the generalized Δ self-consistent field density functional theory (Δ-SCF DFT) calculations, we attribute the experimentally observed absorption band at 430-550 nm...

The effects of three absorption-modifying critical excipients on the in vivo intestinal absorption of six model compounds in rats and dogs.

Science.gov (United States)

David, Dahlgren; Carl, Roos; Pernilla, Johansson; Christer, Tannergren; Anders, Lundqvist; Peter, Langguth; Markus, Sjöblom; Erik, Sjögren; Hans, Lennernäs

2018-05-11

Pharmaceutical excipients that may affect gastrointestinal (GI) drug absorption are called critical pharmaceutical excipients (CPEs), or absorption-modifying excipients (AMEs) if they act by altering the integrity of the intestinal epithelial cell membrane. Some of these excipients increase intestinal permeability, and subsequently the absorption and bioavailability of the drug. This could have implications for both the assessment of bioequivalence and the efficacy of the absorption-enhancing drug delivery system. The absorption-enhancing effects of AMEs/CPEs with different mechanisms (chitosan, sodium caprate, sodium dodecyl sulfate (SDS)) have previously been evaluated in the rat single-pass intestinal perfusion (SPIP) model. However, it remains unclear whether these SPIP data are predictive in a more in vivo like model. The same excipients were in this study evaluated in rat and dog intraintestinal bolus models. SDS and chitosan did exert an absorption-enhancing effect in both bolus models, but the effect was substantially lower than those observed in the rat SPIP model. This illustrates the complexity of the AME/CPE effects, and indicates that additional GI physiological factors need to be considered in their evaluation. We therefore recommend that AME/CPE evaluations obtained in transit-independent, preclinical permeability models (e.g. Ussing, SPIP) should be verified in animal models better able to predict in vivo relevant GI effects, at multiple excipient concentrations. Copyright © 2018. Published by Elsevier B.V.

Linking Transformational Leadership, Absorptive Capacity, and Corporate Entrepreneurship

Directory of Open Access Journals (Sweden)

Imran Shafique

2018-03-01

Full Text Available This study aims to analyze the nexus between transformational leadership and corporate entrepreneurship through an integration of dispersed scholarly work on transformational leadership, absorptive capacity, and corporate entrepreneurship under one framework. A survey method was employed for the collection of data from small and medium-sized enterprises (SMEs of Pakistan. The data were analyzed using structural equation modeling (SEM technique to empirically test the hypotheses. The results demonstrate that transformational leadership positively affects corporate entrepreneurship and its dimensions—namely, innovation, new business venturing, self-renewal, proactivity, and risk-taking—both directly and through absorptive capacity. The potential of transformational leadership to influence corporate entrepreneurship via absorptive capacity added additional interesting substitutes. Future studies may produce novel insights by examining different leadership styles, settings, or utilizing qualitative technique. Firms should invest to initiate transformational leadership training programs for their managers. Additionally, if these firms are aiming to promote corporate entrepreneurship, they should focus on hiring managers that have attributes of transformational leadership. Furthermore, they should also invest in absorptive capacity to utilize outside knowledge for the enhancement of entrepreneurial activities. This study exploits research work on the relationship between transformational leadership and corporate entrepreneurship in a novel way; it investigates the dimensions of entrepreneurship individually, as well as unidimensionally, and includes the mediating role of absorptive capacity and tests several other hypotheses that previously have been ignored. This study, compared to the existing research, contributes to the impact of transformational leadership on corporate entrepreneurship and absorptive capacity, especially in Pakistan�

Bulk damage and absorption in fused silica due to high-power laser applications

Science.gov (United States)

Nürnberg, F.; Kühn, B.; Langner, A.; Altwein, M.; Schötz, G.; Takke, R.; Thomas, S.; Vydra, J.

2015-11-01

Laser fusion projects are heading for IR optics with high broadband transmission, high shock and temperature resistance, long laser durability, and best purity. For this application, fused silica is an excellent choice. The energy density threshold on IR laser optics is mainly influenced by the purity and homogeneity of the fused silica. The absorption behavior regarding the hydroxyl content was studied for various synthetic fused silica grades. The main absorption influenced by OH vibrational excitation leads to different IR attenuations for OH-rich and low-OH fused silica. Industrial laser systems aim for the maximum energy extraction possible. Heraeus Quarzglas developed an Yb-doped fused silica fiber to support this growing market. But the performance of laser welding and cutting systems is fundamentally limited by beam quality and stability of focus. Since absorption in the optical components of optical systems has a detrimental effect on the laser focus shift, the beam energy loss and the resulting heating has to be minimized both in the bulk materials and at the coated surfaces. In collaboration with a laser research institute, an optical finisher and end users, photo thermal absorption measurements on coated samples of different fused silica grades were performed to investigate the influence of basic material properties on the absorption level. High purity, synthetic fused silica is as well the material of choice for optical components designed for DUV applications (wavelength range 160 nm - 260 nm). For higher light intensities, e.g. provided by Excimer lasers, UV photons may generate defect centers that effect the optical properties during usage, resulting in an aging of the optical components (UV radiation damage). Powerful Excimer lasers require optical materials that can withstand photon energy close to the band gap and the high intensity of the short pulse length. The UV transmission loss is restricted to the DUV wavelength range below 300 nm and

An Empirical Investigation into a Subsidiary Absorptive Capacity Process Model

DEFF Research Database (Denmark)

Schleimer, Stephanie; Pedersen, Torben

2011-01-01

and empirically test a process model of absorptive capacity. The setting of our empirical study is 213 subsidiaries of multinational enterprises and the focus is on the capacity of these subsidiaries to successfully absorb best practices in marketing strategy from their headquarters. This setting allows us...... to explore the process model in its entirety, including different drivers of subsidiary absorptive capacity (organizational mechanisms and contextual drivers), the three original dimensions of absorptive capacity (recognition, assimilation, application), and related outcomes (implementation...... and internalization of the best practice). The study’s findings reveal that managers have discretion in promoting absorptive capacity through the application of specific organizational mechanism and that the impact of contextual drivers on subsidiary absorptive capacity is not direct, but mediated...

Optical absorptions in ZnO/a-Si distributed Bragg reflectors

Energy Technology Data Exchange (ETDEWEB)

Chen, Aqing, E-mail: aqchen@hdu.edu.cn; Chen, Zhian [Hangzhou Dianzi University, College of Materials & Environmental Engineering (China); Zhu, Kaigui [Beihang University, Department of physics (China); Ji, Zhenguo [Hangzhou Dianzi University, College of Materials & Environmental Engineering (China)

2017-01-15

The distributed Bragg reflectors (DBRs) consisting of alternating layers of ZnO and heavy doped amorphous silicon (a-Si) have been fabricated by magnetron sputtering. It is novel to find that the optical absorptions exist in the stopband of the DBRs, and that many discrete strong optical absorption peaks exist in the wavelength range of visible to near-infrared. The calculated results by FDTD show that the absorptions in the stopband mainly exist in the first a-Si layer, and that the light absorbed by other a-Si layers inside contributes to the two absorption peaks in near-infrared range. The strong absorptions ranged from visible to infrared open new possibilities to the enhancement of the performance of amorphous silicon solar cells.

[INVITED] Coherent perfect absorption of electromagnetic wave in subwavelength structures

Science.gov (United States)

Yan, Chao; Pu, Mingbo; Luo, Jun; Huang, Yijia; Li, Xiong; Ma, Xiaoliang; Luo, Xiangang

2018-05-01

Electromagnetic (EM) absorption is a common process by which the EM energy is transformed into other kinds of energy in the absorber, for example heat. Perfect absorption of EM with structures at subwavelength scale is important for many practical applications, such as stealth technology, thermal control and sensing. Coherent perfect absorption arises from the interplay of interference and absorption, which can be interpreted as a time-reversed process of lasing or EM emitting. It provides a promising way for complete absorption in both nanophotonics and electromagnetics. In this review, we discuss basic principles and properties of a coherent perfect absorber (CPA). Various subwavelength structures including thin films, metamaterials and waveguide-based structures to realize CPAs are compared. We also discuss the potential applications of CPAs.

Absorption from multicomponent gas mixtures comparing with Elemir gasoline plant

Energy Technology Data Exchange (ETDEWEB)

Miscevic, D

1970-10-01

A short description and explanation are outlined of all factors which have influence on hydrocarbon absorption from multicomponent gas mixtures. A short review of these different methods for absorption efficiency calculation is given. On the basis of the explained methods, the absorption from one natural gas at the Elemir plant is calculated and the results are given in tabular data. The number of the theoretical plate and L/V ratio for a given recovery of the key component is fixed by the calculation and by a graphical solution. Special attention is given for absorption oil depending on gas flow, pressure, and temperature. A series of diagrams is presented showing required absorption oil at the Elemir plant for given propane recovery, depending on the variables which are mentioned.