International Nuclear Information System (INIS)
Binzoni, T; Leung, T S; Ruefenacht, D; Delpy, D T
2006-01-01
Based on quasi-elastic scattering theory (and random walk on a lattice approach), a model of laser-Doppler flowmetry (LDF) has been derived which can be applied to measurements in large tissue volumes (e.g. when the interoptode distance is >30 mm). The model holds for a semi-infinite medium and takes into account the transport-corrected scattering coefficient and the absorption coefficient of the tissue, and the scattering coefficient of the red blood cells. The model holds for anisotropic scattering and for multiple scattering of the photons by the moving scatterers of finite size. In particular, it has also been possible to take into account the simultaneous presence of both Brownian and pure translational movements. An analytical and simplified version of the model has also been derived and its validity investigated, for the case of measurements in human skeletal muscle tissue. It is shown that at large optode spacing it is possible to use the simplified model, taking into account only a 'mean' light pathlength, to predict the blood flow related parameters. It is also demonstrated that the 'classical' blood volume parameter, derived from LDF instruments, may not represent the actual blood volume variations when the investigated tissue volume is large. The simplified model does not need knowledge of the tissue optical parameters and thus should allow the development of very simple and cost-effective LDF hardware
International Nuclear Information System (INIS)
Warncke, D; Lewis, E; Leahy, M; Lochmann, S
2009-01-01
The propagation of light in biological tissue depends on the absorption and reduced scattering coefficient. The aim of this project is the determination of these two optical properties using spatially resolved reflectance measurements. The sensor system consists of five laser sources at different wavelengths, an optical fibre probe and five photodiodes. For these kinds of measurements it has been shown that an often used solution of the diffusion equation can not be applied. Therefore a neural network is being developed to extract the needed optical properties out of the reflectance data. Data sets for the training, validation and testing process are provided by Monte Carlo Simulations.
Spectroscopic method for determination of the absorption coefficient in brain tissue
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.
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
Fukutomi, D.; Ishii, K.; Awazu, K.
2015-12-01
Anisotropy factor g, one of the optical properties of biological tissues, is the most important parameter to accurately determine scattering coefficient μs in the inverse Monte Carlo (iMC) simulation. It has been reported that g has wavelength and absorption dependence, however, there are few attempts in order to calculate μs of biological tissue considering the wavelength and absorption dependence of g. In this study, the scattering angular distributions of biological tissue phantoms were measured in order to determine g by using goniometric measurements with three polarization conditions at strongly and weakly absorbing wavelengths of hemoglobin. Then, optical properties, especially, μs were measured by integrating sphere measurements and iMC simulation in order to confirm the influence of measured g on optical properties in comparison of with general value of g (0.9) for soft biological tissue. Consequently, it was found that μs was overestimated at strongly absorbing wavelength, however, μs was underestimated at weakly absorbing wavelength if the g was not considered its wavelength and absorption dependence.
Fukutomi, Daichi; Ishii, Katsunori; Awazu, Kunio
2016-04-01
The anisotropy factor g, one of the optical properties of biological tissues, has a strong influence on the calculation of the scattering coefficient μ s in inverse Monte Carlo (iMC) simulations. It has been reported that g has the wavelength and absorption dependence; however, few attempts have been made to calculate μ s using g values by taking the wavelength and absorption dependence into account. In this study, the angular distributions of scattered light for biological tissue phantoms containing hemoglobin as a light absorber were measured by a goniometric optical setup at strongly (405 nm) and weakly (664 nm) absorbing wavelengths to obtain g. Subsequently, the optical properties were calculated with the measured values of g by integrating sphere measurements and an iMC simulation, and compared with the results obtained with a conventional g value of 0.9. The μ s values with measured g were overestimated at the strongly absorbing wavelength, but underestimated at the weakly absorbing wavelength if 0.9 was used in the iMC simulation.
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...
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...
Determination of optical absorption coefficient with focusing photoacoustic imaging.
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.
Directory of Open Access Journals (Sweden)
Cornescu Gabriela Maria
2015-01-01
Full Text Available The aim of this study was to evaluate effects of organic sources of manganese (Mn and iron (Fe and inulin in diets for laying hens on absorption of these minerals and their deposition in egg and tissue. The study was conducted on 90 Lohmann Brown laying hens in the period from 46-52 weeks of age, assigned to 3 groups with 30 hens/group and 3 hens/cage. The hens from the control group (C received a diet based on corn, rice bran and soybean meal with 16% of crude protein, as well as 60 mg Fe/kg and 71.9 mg Mn/kg of diet in form of inorganic salts. The formulation of the experimental diets (E1 and E2 differed from C group diet by the replacement of inorganic Fe and Mn salts by organometallic chelates of these elements, at a level of 25% lower than in the premix for group C. As source of inulin, group E1 diet also included 0.5% of dry Jerusalem artichoke, while group E2 diet included 0.5% of a product based on chicory root extract. At the end of the experiment, 6 hens from each group were slaughtered and blood serum and liver samples were collected and assayed for concentration of Fe and Mn. In the final week of the experiment, 18 eggs/group were collected for determination of Fe and Mn concentration in egg yolk. Concentration of measured blood serum parameters (haemoglobin, haematocrit, Fe and Mn in experimental (E groups were lower than in group C, but no significant differences (P>0.05 were registered. Absorption coefficients of Mn had higher values in E groups than in group C, with significant increase (P0.05 between groups were observed for Mn and Fe concentration in egg yolk.
Absorption coefficients of silicon: A theoretical treatment
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.
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.
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....
Regularity of the Interband Light Absorption Coefficient
Indian Academy of Sciences (India)
In this paper we consider the interband light absorption coefficient (ILAC), in a symmetric form, in the case of random operators on the -dimensional lattice. We show that the symmetrized version of ILAC is either continuous or has a component which has the same modulus of continuity as the density of states.
Absorption coefficient instrument for turbid natural waters
Friedman, E.; Cherdak, A.; Poole, L.; Houghton, W.
1980-01-01
The paper presents an instrument that directly measures multispectral absorption coefficient of turbid natural water. Attention is given to the design, which is shown to incorporate methods for the compensation of variation in the internal light source intensity, correction of the spectrally dependent nature of the optical elements, and correction for variation in the background light level. In addition, when used in conjunction with a spectrally matched total attenuation instrument, the spectrally dependent scattering coefficient can also be derived. Finally, it is reported that systematic errors associated with multiple scattering have been estimated using Monte Carlo techniques.
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
Axially symmetric reconstruction of plasma emission and absorption coefficients
International Nuclear Information System (INIS)
Yang Lixin; Jia Hui; Yang Jiankun; Li Xiujian; Chen Shaorong; Liu Xishun
2013-01-01
A layered structure imaging model is developed in order to reconstruct emission coefficients and absorption coefficients simultaneously, in laser fusion core plasma diagnostics. A novel axially symmetric reconstruction method that utilizes the LM (Levenberg-Marquardt) nonlinear least squares minimization algorithm is proposed based on the layered structure. Numerical simulation results demonstrate that the proposed method is sufficiently accurate to reconstruct emission coefficients and absorption coefficients, and when the standard deviation of noise is 0.01, the errors of emission coefficients and absorption coefficients are 0.17, 0.22, respectively. Furthermore, this method could perform much better on reconstruction effect compared with traditional inverse Abel transform algorithms. (authors)
Peng, Dong-qing; Zhu, Li-li; Li, Zhi-fang; Li, Hui
2017-09-01
Absorption coefficient of biological tissue is an important parameter in biomedicine, but its determination remains a challenge. In this paper, we propose a method using focusing photoacoustic imaging technique and internal light irradiation of cylindrical diffusing fiber (CDF) to quantify the target optical absorption coefficient. Absorption coefficients for ink absorbers are firstly determined through photoacoustic and spectrophotometric measurements at the same excitation, which demonstrates the feasibility of this method. Also, the optical absorption coefficients of ink absorbers with several concentrations are measured. Finally, the two-dimensional scanning photoacoustic image is obtained. Optical absorption coefficient measurement and simultaneous photoacoustic imaging of absorber non-invasively are the typical characteristics of the method. This method can play a significant role for non-invasive determination of blood oxygen saturation, the absorption-based imaging and therapy.
Aerosol Angstrom Absorption Coefficient Comparisons during MILAGRO.
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.
Calculation of effective absorption coefficient for aerosols of internal mixture
International Nuclear Information System (INIS)
Xu Bo; Huang Yinbo; Fan Chengyu; Qiao Chunhong
2012-01-01
The effective absorption coefficient with time of strong absorbing aerosol made of carbon dusts and water of internal mixture is analyzed, and the influence of different wavelengths and radius ratios on it is discussed. The shorter the wavelength is, the larger the effective absorption coefficient is , and more quickly it increases during 1-100 μs, and the largest increase if 132.65% during 1-100 μs. Different ratios between inner and outer radius have large influence on the effective absorption coefficient. The larger the ratio is, the larger the effective absorption coefficient is, and more quickly it increases during 1-100 μs. The increase of the effective absorption coefficient during 1-100 μs is larger than that during 100-1000 μs, and the largest increase is 138.66% during 1-100 μs. (authors)
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
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.
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)
Restricted mass energy absorption coefficients for use in dosimetry
International Nuclear Information System (INIS)
Brahme, A.
1977-02-01
When matter is irradiated by a photon beam the fraction of energy absorbed locally in some region Rsub(Δ) (where the size of the region Rsub(Δ) is related to the range of secondary electrons of some restriction energy Δ) is expressed by the restricted mass energy absorption coefficient. In this paper an example is given of how restricted mass energy absorption coefficients can be calculated from existing differential photon interaction cross sections. Some applications of restricted mass absorption coefficients in dosimetry are also given. (B.D.)
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
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.
Effect of applied mechanical stress on absorption coefficient of compounds
Energy Technology Data Exchange (ETDEWEB)
Gupta, Manoj Kumar, E-mail: mkgupta.sliet@gmail.com [Department of Applied Sciences, Bhai Gurdas Institute of Engineering and Technology, Sangrur (India); Singh, Gurinderjeet; Dhaliwal, A. S.; Kahlon, K. S. [Department of Physics, Sant Longowal Institute of Engineering & Technology Deemed University, Longowal (Sangrur) India-148106 (India)
2015-08-28
The absorption coefficient of given materials is the parameter required for the basic information. The measurement of absorption coefficient of compounds Al{sub 2}O{sub 3}, CaCO{sub 3}, ZnO{sub 2}, SmO{sub 2} and PbO has been taken at different incident photon energies 26, 59.54, 112, 1173, 1332keV. The studies involve the measurements of absorption coefficient of the self supporting samples prepared under different mechanical stress. This mechanical stress is render in terms of pressure up to 0-6 ton by using hydraulic press. Measurements shows that absorption coefficient of a material is directly proportional to applied mechanical stress on it up to some extent then become independent. Experimentally measured results are in fairly good agreement with in theoretical values obtained from WinXCOM.
Use of appropriate absorption coefficients in gamma-ray dosimetry
International Nuclear Information System (INIS)
Gopinath, D.V.; Natarajan, A.; Subbaiah, K.V.
1985-01-01
The current use of the different types of absorption coefficients in the computation of γ-ray energy deposition rates and air dose is critically analyzed. Transport calculations are presented to bring out the errors associated with the use of different absorption coefficients. It is observed that except for source energies in the range of 0.3 to 3.0 MeV the consistent use of the absorption coefficient, μ/sub a/ results in an underestimate of the air dose everywhere and of energy deposition at regions away from source. The underestimate becomes more significant with increased atomic number (Z) of the medium. Based on the computations and analysis it is concluded that the absorption coefficients μ/sub a/ and μ/sub k/ are of very limited use in practical γ-ray dosimetry
International Nuclear Information System (INIS)
Korneev, N.A.; Sirotkin, A.N.; Rasin, I.M.; Sarapul'tsev, I.A.; Abramova, T.N.
1986-01-01
Sheep taken as example, the new method for calculation of the coefficient of radionuclide ( 65 Zn) absorption in gastrointestinal tract (GIT) is suggested. It is shown that the radionuclide absorption process of sheep lasted 35 h. In case of parenteral intake radionuclide excretion from tissues and organs and its inclusion in structural parts of blood occurs. In animals to which 65 Zn is injected orally, the same processes at 65 Zn simultaneous absorption in GIT during 35 h take place. In 35 hours after radio nuclide injection its absorption coefficient in the GIT of sheep constituted 10.1+-0.05%. Using traditional calculation methods the 65 Zn absorption coefficient for the first 24 h constituted 6.6%
Techniques For Measuring Absorption Coefficients In Crystalline Materials
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.
Determination of sedimentation rates and absorption coefficient of ...
African Journals Online (AJOL)
DR. MIKE HORSFALL
particles have pores that can absorb radiation. Gamma rays have been used to study the absorption coefficients of cobalt(II) insoluble compounds (Essien and Ekpe, 1998), densities of marine sediments. (Gerland and Villinger, 1995) and soil particle-size distribution (Vaz et al., 1992). In this study, sedimentation rates of ...
Lifshitz Tails for the Interband Light Absorption Coefficient
Indian Academy of Sciences (India)
In this paper we consider the interband light absorption coefficient (ILAC) for various models. We show that at the lower and upper edges of the spectrum the Lifshitz tails behaviour of the density of states implies similar behaviour for the ILAC at appropriate energies. The Lifshitz tails property is also exhibited at some points ...
Estimation of water absorption coefficient using the TDR method
Suchorab, Zbigniew; Majerek, Dariusz; Brzyski, Przemysław; Sobczuk, Henryk; Raczkowski, Andrzej
2017-07-01
Moisture accumulation and transport in the building barriers is an important feature that influences building performance, causing serious exploitation problems as increased energy use, mold and bacteria growth, decrease of indoor air parameters that may lead to sick building syndrome (SBS). One of the parameters that is used to describe moisture characteristic of the material is water absorption coefficient being the measure of capillary behavior of the material as a function of time and the surface area of the specimen. As usual it is determined using gravimetric methods according to EN 1925:1999 standard. In this article we demonstrate the possibility of determination of water absorption coefficient of autoclaved aerated concrete (AAC) using the Time Domain Reflectometry (TDR) method. TDR is an electric technique that had been adopted from soil science and can be successfully used for real-time monitoring of moisture transport in building materials and envelopes. Data achieved using TDR readouts show high correlation with standard method of moisture absorptivity coefficient determination.
Coefficient of Friction of Human Corneal Tissue.
Wilson, Tawnya; Aeschlimann, Rudolf; Tosatti, Samuele; Toubouti, Youssef; Kakkassery, Joseph; Osborn Lorenz, Katherine
2015-09-01
A novel property evaluation methodology was used to determine the elusive value for the human corneal coefficient of friction (CoF). Using a microtribometer on 28 fresh human donor corneas with intact epithelia, the CoF was determined in 4 test solutions (≥5 corneas/solution): tear-mimicking solution (TMS) in borate-buffered saline (TMS-PS), TMS in phosphate-buffered saline (TMS-PBS), TMS with HEPES-buffered saline (TMS-HEPES), and tear-like fluid in PBS (TLF-PBS). Mean (SD) CoF values ranged from 0.006 to 0.015 and were 0.013 (0.010) in TMS-PS, 0.006 (0.003) in TMS-PBS, 0.014 (0.005) in TMS-HEPES, and 0.015 (0.009) in TLF-PBS. Statistically significant differences were shown for TMS-PBS versus TLF (P = 0.0424) and TMS-PBS versus TMS-HEPES (P = 0.0179), but not for TMS-PBS versus TMS-PS (P = 0.2389). Successful measurement of the fresh human corneal tissue CoF was demonstrated, with values differing in the evaluated buffer solutions, within this limited sample size.
Midgley, S M
2004-01-21
A novel parameterization of x-ray interaction cross-sections is developed, and employed to describe the x-ray linear attenuation coefficient and mass energy absorption coefficient for both elements and mixtures. The new parameterization scheme addresses the Z-dependence of elemental cross-sections (per electron) using a simple function of atomic number, Z. This obviates the need for a complicated mathematical formalism. Energy dependent coefficients describe the Z-direction curvature of the cross-sections. The composition dependent quantities are the electron density and statistical moments describing the elemental distribution. We show that it is possible to describe elemental cross-sections for the entire periodic table and at energies above the K-edge (from 6 keV to 125 MeV), with an accuracy of better than 2% using a parameterization containing not more than five coefficients. For the biologically important elements 1 coefficients. At higher energies, the parameterization uses fewer coefficients with only two coefficients needed at megavoltage energies.
International Nuclear Information System (INIS)
Pelivanov, Ivan M; Barskaya, M I; Podymova, N B; Khokhlova, Tanya D; Karabutov, Aleksander A
2009-01-01
The second part of this work describes the experimental technique of measuring the local light absorption in turbid media. The technique is based on the measurement of the amplitude of an opto-acoustic (OA) signal excited in a turbid medium under the condition of one-sided access to the object under study. An OA transducer is developed to perform the proposed measurement procedure. Experiments are conducted for the turbid media with different optical properties (light absorption and reduced scattering coefficients) and for different diameters of the incident laser beam. It is found that the laser beam diameter can be chosen so that the dependences of the measured OA signal amplitude on the light absorption coefficient coincide upon varying the reduced scattering coefficient by more than twice. The obtained numerical and experimental results demonstrate that the OA method is applicable for measuring the local light absorption coefficient in turbid media, for example, in biological tissues. (measurement of parametrs of laser radiation)
Absorption Coefficient in Periodic InAs/GaAs Nanostructures
Energy Technology Data Exchange (ETDEWEB)
Rodriguez-BolIvar, S; Gomez-Campos, F M; Luque-Rodriguez, A; Lopez-Villanueva, J A; Carceller, J E, E-mail: fmgomez@ugr.e [Departamento de Electronica y TecnologIa de los Computadores, Facultad de Ciencias, Av. Fuentenueva s/n, C. P. 18071, Universidad de Granada (Spain)
2010-09-01
Periodic nanostructure manufacture has been proposed as a procedure for obtaining new materials with tunable physical properties, such as the photon absorption coefficient. In this work we have theoretically investigated this quantity in ordered InAs/GaAs cubic quantum dot systems. We solved the Schroedinger equation associated with these structures, using a set of 13x13x13 plane waves at 12,167 equally spaced points of the Q space. We focused on the transitions between minibands arising from the conduction band. We took into account the different effective masses in each material. We included the effects of the strain by taking a conduction band offset of 0.5 eV, corresponding to strained InAs in GaAs
Optical absorption and scattering spectra of pathological stomach tissues
Giraev, K. M.; Ashurbekov, N. A.; Lakhina, M. A.
2011-03-01
Diffuse reflection spectra of biotissues in vivo and transmission and reflection coefficients for biotissues in vitro are measured over 300-800 nm. These data are used to determine the spectral absorption and scattering indices and the scattering anisotropy factor for stomach mucous membranes under normal and various pathological conditions (chronic atrophic and ulcerous defects, malignant neoplasms). The most importan tphysiological (hemodynamic and oxygenation levels) and structural-morphological (scatterer size and density) parameters are also determined. The results of a morphofunctional study correlate well with the optical properties and are consistent with data from a histomorphological analysis of the corresponding tissues.
Xenon tissue/blood partition coefficient for pig urinary bladder
DEFF Research Database (Denmark)
Nielsen, K K; Bülow, J; Nielsen, S L
1990-01-01
In four landrace pigs the tissue/blood partition coefficient (lambda) for xenon (Xe) for the urinary bladder was calculated after chemical analysis for lipid, water and protein content and determination of the haematocrit. The coefficients varied from bladder to bladder owing to small differences...
Measured and numerically partitioned phytoplankton spectral absorption coefficients in inland waters
Zhang, Y.; Liu, M.; Van Dijk, M.A.; Zhu, G.; Gong, Z.; Li, Y.M.; Qin, B.
2009-01-01
Total particulate, tripton and phytoplankton absorption coefficients were measured for eutrophic (Lake Taihu), meso-eutrophic (Lake Tianmuhu) and mesotrophic waters (the Three Gorges Reservoir) in China using the quantitative filter technique. Meanwhile, tripton and phytoplankton absorption
Light Absorption Coefficients for Soluble Species in Snow, Dome C, Antarctica, Version 1
National Aeronautics and Space Administration — This data set contains light absorption coefficients for soluble chromophores (light-absorbing chemicals) and concentrations of hydrogen peroxide (HOOH) and nitrate...
Prabhakaran, Sai Shri; Sahu, Sanjay Kumar; Dev, Pravin Jeba; Shanmugam, Palanisamy
2018-05-01
Spectral absorption coefficients of particulate (algal and non-algal components) and dissolved substances are modelled and combined with the pure seawater component to determine the total light absorption coefficients of seawater in the Bay of Bengal. Two parameters namely chlorophyll-a (Chl) concentration and turbidity were measured using commercially available instruments with high sampling rates. For modelling the light absorption coefficients of oceanic waters, the measured data are classified into two broad groups - algal dominant and non-algal particle (NAP) dominant. With these criteria the individual absorption coefficients of phytoplankton and NAP were established based on their concentrations using an iterative method. To account for the spectral dependence of absorption by phytoplankton, the wavelength-dependent coefficients were introduced into the model. The CDOM absorption was determined by subtracting the individual absorption coefficients of phytoplankton and NAP from the measured total absorption data and then related to the Chl concentration. Validity of the model is assessed based on independent in-situ data from certain discrete locations in the Bay of Bengal. The total absorption coefficients estimated using the new model by considering the contributions of algal, non-algal and CDOM have good agreement with the measured total absorption data with the error range of 6.9 to 28.3%. Results obtained by the present model are important for predicting the propagation of the radiant energy within the ocean and interpreting remote sensing observation data.
Microwave reflection, transmission, and absorption by human brain tissue
Ansari, M. A.; Akhlaghipour, N.; Zarei, M.; Niknam, A. R.
2018-04-01
These days, the biological effects of electromagnetic (EM) radiations on the brain, especially in the frequency range of mobile communications, have caught the attention of many scientists. Therefore, in this paper, the propagation of mobile phone electromagnetic waves in the brain tissues is investigated analytically and numerically. The brain is modeled by three layers consisting of skull, grey and white matter. First, we have analytically calculated the microwave reflection, transmission, and absorption coefficients using signal flow graph technique. The effect of microwave frequency and variations in the thickness of layers on the propagation of microwave through brain are studied. Then, the penetration of microwave in the layers is numerically investigated by Monte Carlo method. It is shown that the analytical results are in good agreement with those obtained by Monte Carlo method. Our results indicate the absorbed microwave energy depends on microwave frequency and thickness of brain layers, and the absorption coefficient is optimized at a number of frequencies. These findings can be used for comparing the microwave absorbed energy in a child's and adult's brain.
Temperature dependence of the absorption coefficient of water for midinfrared laser radiation
Jansen, E. D.; van Leeuwen, T. G.; Motamedi, M.; Borst, C.; Welch, A. J.
1994-01-01
The dynamics of the water absorption peak around 1.94 microns was examined. This peak is important for the absorption of holmium and thulium laser radiation. To examine the effect of temperature on the absorption coefficient, the transmission of pulsed Ho:YAG, Ho:YAG, Ho:YSGG, and Tm:YAG laser
Chloride absorption by root, leaf and floral tissues of Petunia
International Nuclear Information System (INIS)
Jooste, J.H.
1980-01-01
Chloride absorption by root, leaf and floral tissues of Petunia was compared at two temperatures (30 and 2 degrees Celcius), employing different absorption periods, and in the presence and absence of a desorption treatment. All treatments revealed highest absorption by floral tissue. This was further confirmed by the absorption of chloride by the various tissues from solutions in the low (0-1 mM) and high (1-50 mM) concentration ranges. The results offer a possible explanation for the observed effects of organic and inorganic solutes on the longevity of cut flowers [af
A method for determination mass absorption coefficient of gamma rays by Compton scattering
International Nuclear Information System (INIS)
El Abd, A.
2014-01-01
A method was proposed for determination mass absorption coefficient of gamma rays for compounds, alloys and mixtures. It is based on simulating interaction processes of gamma rays with target elements having atomic numbers from Z=1 to Z=92 using the MCSHAPE software. Intensities of Compton scattered gamma rays at saturation thicknesses and at a scattering angle of 90° were calculated for incident gamma rays of different energies. The obtained results showed that the intensity of Compton scattered gamma rays at saturations and mass absorption coefficients can be described by mathematical formulas. These were used to determine mass absorption coefficients for compound, alloys and mixtures with the knowledge of their Compton scattered intensities. The method was tested by calculating mass absorption coefficients for some compounds, alloys and mixtures. There is a good agreement between obtained results and calculated ones using WinXom software. The advantages and limitations of the method were discussed. - Highlights: • Compton scattering of γ−rays was used for determining mass absorption coefficient. • Scattered intensities were determined by the MCSHAPE software. • Mass absorption coefficients were determined for some compounds, mixtures and alloys. • Mass absorption coefficients were calculated by Winxcom software. • Good agreements were found between determined and calculated results
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.
Absorption coefficients for water vapor at 193 nm from 300 to 1073 K
Kessler, W. J.; Carleton, K. L.; Marinelli, W. J.
1993-01-01
Measurements of the water absorption coefficient at 193 nm from 300 to 1073 K are reported. The measurements were made using broadband VUV radiation and a monochromator-based detection system. The water vapor was generated by a saturator and metered into a flowing, 99 cm absorption cell via a water vapor mass flow meter. The 193 nm absorption coefficient measurements are compared to room temperature and high temperature shock tube measurements with good agreement. The absorption can be parameterized by a nu3 vibrational mode reaction coordinate and the thermal population of the nu3 mode.
Directory of Open Access Journals (Sweden)
R. Golmohammadi
2008-04-01
Full Text Available Introduction & Objective: Noise is one of the most important harmful agents in work environment. In spit of industrial improvements, exposure with over permissible limit of noise is counted as one of the health complication of workers. In Iran, do not exact information of the absorption coefficient of acoustic materials. Iranian manufacturer have not laboratory for measured of sound absorbance of their products, therefore using of sound absorber is limited for noise control in industrial and non industrial constructions. The goal of this study was to design an impedance tube based on pressure method for measurement of the sound absorption coefficient of acoustic materials.Materials & Methods: In this study designing of measuring system and method of calculation of sound absorption based on a available equipment and relatively easy for measurement of the sound absorption coefficient related to ISO10534-1 was performed. Measuring system consist of heavy asbestos tube, a pure tone sound generator, calibrated sound level meter for measuring of some commonly of sound absorber materials was used. Results: In this study sound absorption coefficient of 23 types of available acoustic material in Iran was tested. Reliability of results by three repeat of measurement was tested. Results showed that the standard deviation of sound absorption coefficient of study materials was smaller than .Conclusion: The present study performed a necessary technology of designing and producing of impedance tube for determining of acoustical materials absorption coefficient in Iran.
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.
International Nuclear Information System (INIS)
Cherkasov, M.R.
1995-01-01
Based on the general principles of semiclassical electrodynamics, the Bouguer law is derived, and the expression for the absorption coefficient is obtained, formally including all effects related to the phenomenon of spatial dispersion
A method for determination mass absorption coefficient of gamma rays by Compton scattering.
El Abd, A
2014-12-01
A method was proposed for determination mass absorption coefficient of gamma rays for compounds, alloys and mixtures. It is based on simulating interaction processes of gamma rays with target elements having atomic numbers from Z=1 to Z=92 using the MCSHAPE software. Intensities of Compton scattered gamma rays at saturation thicknesses and at a scattering angle of 90° were calculated for incident gamma rays of different energies. The obtained results showed that the intensity of Compton scattered gamma rays at saturations and mass absorption coefficients can be described by mathematical formulas. These were used to determine mass absorption coefficients for compound, alloys and mixtures with the knowledge of their Compton scattered intensities. The method was tested by calculating mass absorption coefficients for some compounds, alloys and mixtures. There is a good agreement between obtained results and calculated ones using WinXom software. The advantages and limitations of the method were discussed. Copyright © 2014 Elsevier Ltd. All rights reserved.
On the sound absorption coefficient of porous asphalt pavements for oblique incident sound waves
Bezemer-Krijnen, Marieke; Wijnant, Ysbrand H.; de Boer, Andries; Bekke, Dirk; Davy, J.; Don, Ch.; McMinn, T.; Dowsett, L.; Broner, N.; Burgess, M.
2014-01-01
A rolling tyre will radiate noise in all directions. However, conventional measurement techniques for the sound absorption of surfaces only give the absorption coefficient for normal incidence. In this paper, a measurement technique is described with which it is possible to perform in situ sound
Determination of friction coefficient in unconfined compression of brain tissue.
Rashid, Badar; Destrade, Michel; Gilchrist, Michael D
2012-10-01
Unconfined compression tests are more convenient to perform on cylindrical samples of brain tissue than tensile tests in order to estimate mechanical properties of the brain tissue because they allow homogeneous deformations. The reliability of these tests depends significantly on the amount of friction generated at the specimen/platen interface. Thus, there is a crucial need to find an approximate value of the friction coefficient in order to predict a possible overestimation of stresses during unconfined compression tests. In this study, a combined experimental-computational approach was adopted to estimate the dynamic friction coefficient μ of porcine brain matter against metal platens in compressive tests. Cylindrical samples of porcine brain tissue were tested up to 30% strain at variable strain rates, both under bonded and lubricated conditions in the same controlled environment. It was established that μ was equal to 0.09±0.03, 0.18±0.04, 0.18±0.04 and 0.20±0.02 at strain rates of 1, 30, 60 and 90/s, respectively. Additional tests were also performed to analyze brain tissue under lubricated and bonded conditions, with and without initial contact of the top platen with the brain tissue, with different specimen aspect ratios and with different lubricants (Phosphate Buffer Saline (PBS), Polytetrafluoroethylene (PTFE) and Silicone). The test conditions (lubricant used, biological tissue, loading velocity) adopted in this study were similar to the studies conducted by other research groups. This study will help to understand the amount of friction generated during unconfined compression of brain tissue for strain rates of up to 90/s. Copyright © 2012 Elsevier Ltd. All rights reserved.
Hijikata, Hayato; Kozawa, Takahiro; Tagawa, Seiichi; Takei, Satoshi
2009-06-01
A bottom extreme-ultraviolet-sensitive coating (BESC) for evaluation of the absorption coefficients of ultrathin films such as extreme ultraviolet (EUV) resists was developed. This coating consists of a polymer, crosslinker, acid generator, and acid-responsive chromic dye and is formed by a conventional spin-coating method. By heating the film after spin-coating, a crosslinking reaction is induced and the coating becomes insoluble. A typical resist solution can be spin-coated on a substrate covered with the coating film. The evaluation of the linear absorption coefficients of polymer films was demonstrated by measuring the EUV absorption of BESC substrates on which various polymers were spin-coated.
X-ray absorption coefficients of the elements (Li TO Bi, U)
International Nuclear Information System (INIS)
Sasaki, Satoshi.
1990-11-01
The atomic absorption coefficient, μ a , and the mass absorption coefficient, μ/ρ, have been calculated for the elements Li to Bi and U, based on both photoelectric and scattering effects. Tables include the μ a and μ/ρ values (i) at 0.01 A intervals in the wavelength range from 0.1 to 2.89 A and (ii) at 0.0001 A intervals in the neighborhood of the K, L 1 , L 2 , and L 3 absorption edges. (author)
DEFF Research Database (Denmark)
Jeong, Cheol-Ho
2015-01-01
to determine the flow resistivity of a porous material from the Sabine absorption coefficient was investigated through a reliable model. The model for the flow resistivity estimation is based on an equivalent fluid model, i.e., Miki’s model, together with the most advanced model that accounts for edge...... diffraction, named Thomasson’s finite size correction. As input data, a set of the Sabine absorption coefficients in a recent absorption round robin test in 13 European chambers was used. Finally, the flow resistivity of the test specimen is characterized via the Bayesian framework, together...
Li, Zhi; Zhang, Zhao-hui; Zhao, Xiao-yan; Su, Hai-xia; Yan, Fang
2012-04-01
Extracting absorption spectrum in THz band is one of the important aspects in THz applications. Sample's absorption coefficient has a complex nonlinear relationship with its thickness. However, as it is not convenient to measure the thickness directly, absorption spectrum is usually determined incorrectly. Based on the method proposed by Duvillaret which was used to precisely determine the thickness of LiNbO3, the approach to measuring the absorption coefficient spectra of glutamine and histidine in frequency range from 0.3 to 2.6 THz(1 THz = 10(12) Hz) was improved in this paper. In order to validate the correctness of this absorption spectrum, we designed a series of experiments to compare the linearity of absorption coefficient belonging to one kind amino acid in different concentrations. The results indicate that as agreed by Lambert-Beer's Law, absorption coefficient spectrum of amino acid from the improved algorithm performs better linearity with its concentration than that from the common algorithm, which can be the basis of quantitative analysis in further researches.
NMR imaging of cell phone radiation absorption in brain tissue
Gultekin, David H.; Moeller, Lothar
2013-01-01
A method is described for measuring absorbed electromagnetic energy radiated from cell phone antennae into ex vivo brain tissue. NMR images the 3D thermal dynamics inside ex vivo bovine brain tissue and equivalent gel under exposure to power and irradiation time-varying radio frequency (RF) fields. The absorbed RF energy in brain tissue converts into Joule heat and affects the nuclear magnetic shielding and the Larmor precession. The resultant temperature increase is measured by the resonance frequency shift of hydrogen protons in brain tissue. This proposed application of NMR thermometry offers sufficient spatial and temporal resolution to characterize the hot spots from absorbed cell phone radiation in aqueous media and biological tissues. Specific absorption rate measurements averaged over 1 mg and 10 s in the brain tissue cover the total absorption volume. Reference measurements with fiber optic temperature sensors confirm the accuracy of the NMR thermometry. PMID:23248293
Minority carrier diffusion lengths and absorption coefficients in silicon sheet material
Dumas, K. A.; Swimm, R. T.
1980-01-01
Most of the methods which have been developed for the measurement of the minority carrier diffusion length of silicon wafers require that the material have either a Schottky or an ohmic contact. The surface photovoltage (SPV) technique is an exception. The SPV technique could, therefore, become a valuable diagnostic tool in connection with current efforts to develop low-cost processes for the production of solar cells. The technique depends on a knowledge of the optical absorption coefficient. The considered investigation is concerned with a reevaluation of the absorption coefficient as a function of silicon processing. A comparison of absorption coefficient values showed these values to be relatively consistent from sample to sample, and independent of the sample growth method.
Fallica, Roberto; Stowers, Jason K.; Grenville, Andrew; Frommhold, Andreas; Robinson, Alex P. G.; Ekinci, Yasin
2016-07-01
The dynamic absorption coefficients of several chemically amplified resists (CAR) and non-CAR extreme ultraviolet (EUV) photoresists are measured experimentally using a specifically developed setup in transmission mode at the x-ray interference lithography beamline of the Swiss Light Source. The absorption coefficient α and the Dill parameters ABC were measured with unprecedented accuracy. In general, the α of resists match very closely with the theoretical value calculated from elemental densities and absorption coefficients, whereas exceptions are observed. In addition, through the direct measurements of the absorption coefficients and dose-to-clear values, we introduce a new figure of merit called chemical sensitivity to account for all the postabsorption chemical reaction ongoing in the resist, which also predicts a quantitative clearing volume and clearing radius, due to the photon absorption in the resist. These parameters may help provide deeper insight into the underlying mechanisms of the EUV concepts of clearing volume and clearing radius, which are then defined and quantitatively calculated.
Wang, D.; Cui, Y.
2015-12-01
The objectives of this paper are to validate the applicability of a multi-band quasi-analytical algorithm (QAA) in retrieval absorption coefficients of optically active constituents in turbid coastal waters, and to further improve the model using a proposed semi-analytical model (SAA). The ap(531) and ag(531) semi-analytically derived using SAA model are quite different from the retrievals procedures of QAA model that ap(531) and ag(531) are semi-analytically derived from the empirical retrievals results of a(531) and a(551). The two models are calibrated and evaluated against datasets taken from 19 independent cruises in West Florida Shelf in 1999-2003, provided by SeaBASS. The results indicate that the SAA model produces a superior performance to QAA model in absorption retrieval. Using of the SAA model in retrieving absorption coefficients of optically active constituents from West Florida Shelf decreases the random uncertainty of estimation by >23.05% from the QAA model. This study demonstrates the potential of the SAA model in absorption coefficients of optically active constituents estimating even in turbid coastal waters. Keywords: Remote sensing; Coastal Water; Absorption Coefficient; Semi-analytical Model
Measurement of the sound absorption coefficient for an advanced undergraduate physics laboratory
Macho-Stadler, E.; Elejalde-García, M. J.
2017-09-01
We present a simple experiment that allows advanced undergraduates to learn the basics of the acoustic properties of materials. The impedance tube-standing wave method is applied to study the normal absorption coefficient of acoustics insulators. The setup includes a tube, a speaker, a microphone, a digital function generator and an oscilloscope, material available in an undergraduate laboratory. Results of the change of the absorption coefficient with the frequency, the sample thickness and the sample density are analysed and compared with those obtained with a commercial system.
Sound absorption coefficient of coal bottom ash concrete for railway application
Ramzi Hannan, N. I. R.; Shahidan, S.; Maarof, Z.; Ali, N.; Abdullah, S. R.; Ibrahim, M. H. Wan
2017-11-01
A porous concrete able to reduce the sound wave that pass through it. When a sound waves strike a material, a portion of the sound energy was reflected back and another portion of the sound energy was absorbed by the material while the rest was transmitted. The larger portion of the sound wave being absorbed, the lower the noise level able to be lowered. This study is to investigate the sound absorption coefficient of coal bottom ash (CBA) concrete compared to the sound absorption coefficient of normal concrete by carried out the impedance tube test. Hence, this paper presents the result of the impedance tube test of the CBA concrete and normal concrete.
Laboratory measurement of the absorption coefficient of riboflavin for ultraviolet light (365 nm).
Iseli, Hans Peter; Popp, Max; Seiler, Theo; Spoerl, Eberhard; Mrochen, Michael
2011-03-01
Corneal cross-linking (CXL) is an increasingly used treatment technique for stabilizing the cornea in keratoconus. Cross-linking (polymerization) between collagen fibrils is induced by riboflavin (vitamin B2) and ultraviolet light (365 nm). Although reported to reach a constant value at higher riboflavin concentrations, the Lambert-Beer law predicts a linear increase in the absorption coefficient. This work was carried out to determine absorption behavior at different riboflavin concentrations and to further investigate the purported plateau absorption coefficient value of riboflavin and to identify possible bleaching effects. The Lambert-Beer law was used to calculate the absorption coefficient at various riboflavin concentrations. The following investigated concentrations of riboflavin solutions were prepared using a mixture of 0.5% riboflavin and 20% Dextran T500 dissolved in 0.9% sodium chloride solution: 0%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.08%, 0.1%, 0.2%, 0.3%, 0.4%, and 0.5%, and were investigated with and without aperture plate implementation. An additional test series measured the transmitted power at selected riboflavin concentrations over time. In diluted solutions, a linear correlation exists between the absorption coefficient and riboflavin concentration. The absorption coefficient reaches a plateau, but this occurs at a higher riboflavin concentration (0.1%) than previously reported (just above 0.04%). Transmitted light power increases over time, indicating a bleaching effect of riboflavin. The riboflavin concentration can be effectively varied as a treatment parameter in a considerably broader range than previously thought. Copyright 2011, SLACK Incorporated.
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.
Tissue/blood partition coefficients for xenon in various adipose tissue depots in man
DEFF Research Database (Denmark)
Bülow, J; Jelnes, Rolf; Astrup, A
1987-01-01
Tissue/blood partition coefficients (lambda) for xenon were calculated for subcutaneous adipose tissue from the abdominal wall and the thigh, and for the perirenal adipose tissue after chemical analysis of the tissues for lipid, water and protein content. The lambda in the perirenal tissue...... was found to correlate linearly to the relative body weight (RBW) in per cent with the regression equation lambda = 0.045 . RBW + 0.99. The subcutaneous lambda on the abdomen correlated linearly to the local skinfold thickness (SFT) with the equation lambda = 0.22 SFT + 2.99. Similarly lambda on the thigh...... correlated to SFT with the equation lambda = 0.20 . SFT + 4.63. It is concluded that the previously accepted lambda value of 10 is generally too high in perirenal as well as in subcutaneous tissue. Thus, by application of the present regression equations, it is possible to obtain more exact estimates...
Mass attenuation coefficient of chromium and manganese compounds around absorption edge.
Sharanabasappa; Kaginelli, S B; Kerur, B R; Anilkumar, S; Hanumaiah, B
2009-01-01
The total mass attenuation coefficient for Potassium dichromate, Potassium chromate and Manganese acetate compounds are measured at different photon energies 5.895, 6.404, 6.490, 7.058, 8.041 and 14.390 keV using Fe-55, Co-57 and 241Am source with Copper target, radioactive sources. The photon intensity is analyzed using a high resolution HPGe detector system coupled to MCA under good geometrical arrangement. The obtained values of mass attenuation coefficient values are compared with theoretical values. This study suggests that measured mass attenuation coefficient values at and near absorption edges differ from the theoretical value by about 5-28%.
International Nuclear Information System (INIS)
Podest, M.; Klima, J.; Stecher, P.; Stecherova, E.
1978-01-01
UO 2 pellets from ALUOX fuel elements were used in measuring the absorption coefficient of gamma radiation in UO 2 . The results of measurements of the energy dependence of the linear absorption coefficient (within 622 to 796 keV) and of the dependence on pellet density showed that in the given density interval the absorption coefficient was almost constant. The density interval was chosen to be typical for pellet fuel used in water cooled and water moderated power reactors. The results are also shown of the dependence of the mass absorption coefficient of gamma radiation in Zr on radiation energy and compared with the mass absorption coefficient of Mo; these also showed the independence of the absorption coefficient on density. The linear and mass absorption coefficients of UO 2 are considerably high and correspond approximately to the absorption coefficient of lead. For the measured energy range the variation of absorption coefficient is about 40%, which causes errors in burnup determination. The efficiency was also determined of Ge(Li) detectors for the energy range 0.5 to 1.2 MeV. The determination of the above coefficients was used for improving the gamma fuel scanning technique in determining the activity and burnup of spent fuel elements. (J.P.)
International Nuclear Information System (INIS)
Montero, Raul F. Carita; Roberty, Nilson C.; Silva Neto, Antonio J.; Universidade Federal, Rio de Janeiro, RJ
2002-01-01
In the present work it is presented the solution of the two dimensional inverse radiative transfer problem of scattering and absorption coefficients estimation, in heterogeneous media, using the source-detector methodology and a discrete ordinates method consistent with the source-detector system. The mathematical formulation of the direct and inverse problems is presented as well as test case results. (author)
Absorption coefficient of nearly transparent liquids measured using thermal lens spectrometry
Directory of Open Access Journals (Sweden)
H.Cabrera
2006-01-01
Full Text Available We use an optimized pump-probe mode-mismatched thermal lens scheme to determine the optical absorption coefficient and thermal diffusivity of ethanol, benzene, acetone, methanol, toluene and chloroform. In this scheme the excitation beam is focused in the presence of a collimated probe beam. The agreement between experimentally obtained results and values reported in the literature is good.
Guo, Zijian; Favazza, Christopher; Garcia-Uribe, Alejandro; Wang, Lihong V
2012-06-01
Photoacoustic (PA) microscopy (PAM) can image optical absorption contrast with ultrasonic spatial resolution in the optical diffusive regime. Conventionally, accurate quantification in PAM requires knowledge of the optical fluence attenuation, acoustic pressure attenuation, and detection bandwidth. We circumvent this requirement by quantifying the optical absorption coefficients from the acoustic spectra of PA signals acquired at multiple optical wavelengths. With the acoustic spectral method, the absorption coefficients of an oxygenated bovine blood phantom at 560, 565, 570, and 575 nm were quantified with errors of <3%. We also quantified the total hemoglobin concentration and hemoglobin oxygen saturation in a live mouse. Compared with the conventional amplitude method, the acoustic spectral method provides greater quantification accuracy in the optical diffusive regime. The limitations of the acoustic spectral method was also discussed.
National Research Council Canada - National Science Library
Green, Rebecca E; Gould, Jr., Richard W; Ko, Dong S
2008-01-01
... (CDOM) absorption coefficients from physical hydrographic and atmospheric properties. The models were developed for northern Gulf of Mexico shelf waters using multi-year satellite and physical data...
Chlorophyll specific absorption coefficient and phytoplankton biomass in the Red Sea
Tiwari, Surya Prakash
2015-01-01
The role of total particulate matter, the sum of phytoplankton and nonalgal particles, is essential to understanding the distribution and pathways of particulate carbon in the ocean. Their relative contributions to light absorption and scattering are fundamental to understanding remotely sensed ocean color. Until recently, data regarding the contribution of phytoplankton and algal particles to the inherent optical properties of the Red Sea was nonexistent. Some of the first measurements of these inherent optical properties in the Red Sea including phytoplankton specific absorption coefficients (aph*(λ)) were obtained by the TARA Oceans expedition in January 2010. From these observations, chlorophyll a was calculated using the Line Height Method (LHM) that minimizes the contribution to total and particulate absorption by non-algal particles (NAP) and CDOM. Bricaud and Stramski’s (1990) a method was then used to decompose hyperspectral total particulate absorption into the contributions by phytoplankton and nonalgal particles.
Analysis of the absorption coefficient by annealing in carbon implanted Nd: YVO4
International Nuclear Information System (INIS)
Sanchez-Morales, M E; Vazquez, G V; Lifante, G; Cantelar, E; Rickards, J; Trejo-Luna, R
2011-01-01
Low loss in optical waveguides is very important in order to achieve high laser efficiency. Waveguide fabrication by ion implantation generates color centers, leading to absorption losses which can be reduced by annealing; however, this process may eliminate the waveguide and hence it is necessary to consider both the optimum annealing time and temperature. This work reports the behavior of the absorption coefficient by successive annealing steps in Nd:YVO 4 implanted with a dose of 5xl0 14 ions/cm 2 .
Kamaraju, N.; Kumar, Sunil; Sood, A. K.; Guha, Shekhar; Krishnamurthy, Srinivasan; Rao, C. N. R.
2007-12-01
Nonlinear transmission of 80 and 140fs pulsed light with 0.79μm wavelength through single walled carbon nanotubes suspended in water containing sodium dodecyl sulfate is studied. Pulse-width independent saturation absorption and negative cubic nonlinearity are observed, respectively, in open and closed aperture z-scan experiments. The theoretical expressions derived to analyze the z-dependent transmission in the saturable limit require two photon absorption coefficient β0˜1.4cm/MW and a nonlinear index γ ˜-5.5×10-11cm2/W to fit the data.
International Nuclear Information System (INIS)
DeRose, Paul C.; Kramer, Gary W.
2005-01-01
The absorption coefficient of standard reference material[registered] (SRM[registered]) 1932, fluorescein in a borate buffer solution (pH=9.5) has been determined at λ=488.0, 490.0, 490.5 and 491.0 nm using the US national reference UV/visible spectrophotometer. The purity of the fluorescein was determined to be 97.6% as part of the certification of SRM 1932. The solution measured was prepared gravimetrically by diluting SRM 1932 with additional borate buffer. The value of the absorption coefficient was corrected for bias due to fluorescence that reaches the detector and for dye purity. Bias due to fluorescence was found to be on the order of -1% for both monochromatic and polychromatic (e.g., diode-array based) spectrophotometers
Energy absorption coefficients for 662 keV gamma ray in some fatty acids
International Nuclear Information System (INIS)
Bhandal, G.S.; Singh, K.; Rama Rani; Vijay Kumar
1993-01-01
The mass energy absorption coefficient refers to the amount of energy dissipation by the secondary electron set in motion as a result of interactions between incident photons and matter. Under certain conditions, the energy dissipated by electrons in a given volume can be equated to the energy absorbed in that volume. The absorbed energy is of basic interest in radiation dosimetry because it represents the amount of energy made available for the production of chemical or biological effects. Sphere transmission is employed for the direct measurement of mass energy absorption coefficients at 662 keV in some fatty acids. Excellent agreement is obtained between the measured and theoretical values. (author). 6 refs., 1 fig., 1 tab
Mass Absorption Coefficients At 661,6 keV Energy In Various Samples
International Nuclear Information System (INIS)
Suhariyono, Gatot; Bunawas
2000-01-01
Determination mass absorption coefficients (mum) at 661.6 keV energy in the samples various, such as lysine, coffee, chocolate, nutrisari, coconut oil, monosodium glutamate (MSG), tea, tin fish and the soil with experiment method has been carried out. The mum research was carried out in effort to give the measurement result of Cs-137 concentration that more accurate to the samples, because the sample density increases, mass absorption coefficients (mum) decreases. The mum correction on measurement of Cs-137 concentration in the samples various around between 0 and 13%, the highest is on the chocolate sample and the lowest is on the tin fish sample. Density of the samples decreases, the mum influence increases on the counting of Cs-137 concentration in the sample (Bq/kg)
Stopping-power and mass energy-absorption coefficient ratios for Solid Water
International Nuclear Information System (INIS)
Ho, A.K.; Paliwal, B.R.
1986-01-01
The AAPM Task Group 21 protocol provides tables of ratios of average restricted stopping powers and ratios of mean energy-absorption coefficients for different materials. These values were based on the work of Cunningham and Schulz. We have calculated these quantities for Solid Water (manufactured by RMI), using the same x-ray spectra and method as that used by Cunningham and Schulz. These values should be useful to people who are using Solid Water for high-energy photon calibration
Water vapor absorption coefficients in the 8-13-micron spectral region - A critical review
Grant, William B.
1990-01-01
Measurements of water vapor absorption coefficients in the thermal IR atmospheric window (8-13 microns) during the past 20 years obtained by a variety of techniques are reviewed for consistency and compared with computed values based on the AFGL spectral data tapes. The methods of data collection considered were atmospheric long path absorption with a CO2 laser or a broadband source and filters, a White cell and a CO2 laser or a broadband source and a spectrometer, and a spectrophone with a CO2 laser. Advantages and disadvantages of each measurement approach are given as a guide to further research. Continuum absorption has apparently been measured accurately to about the 5-10 percent level in five of the measurements reported.
Modeling of the Interminiband Absorption Coefficient in InGaN Quantum Dot Superlattices
Directory of Open Access Journals (Sweden)
Giovanni Giannoccaro
2016-01-01
Full Text Available In this paper, a model to estimate minibands and theinterminiband absorption coefficient for a wurtzite (WZ indium gallium nitride (InGaN self-assembled quantum dot superlattice (QDSL is developed. It considers a simplified cuboid shape for quantum dots (QDs. The semi-analytical investigation starts from evaluation through the three-dimensional (3D finite element method (FEM simulations of crystal mechanical deformation derived from heterostructure lattice mismatch under spontaneous and piezoelectric polarization effects. From these results, mean values in QDs and barrier regions of charge carriers’ electric potentials and effective masses for the conduction band (CB and three valence sub-bands for each direction are evaluated. For the minibands’ investigation, the single-particle time-independent Schrödinger equation in effective mass approximation is decoupled in three directions and resolved using the one-dimensional (1D Kronig–Penney model. The built-in electric field is also considered along the polar axis direction, obtaining Wannier–Stark ladders. Then, theinterminiband absorption coefficient in thermal equilibrium for transverse electric (TE and magnetic (TM incident light polarization is calculated using Fermi’s golden rule implementation based on a numerical integration into the first Brillouin zone. For more detailed results, an absorption coefficient component related to superlattice free excitons is also introduced. Finally, some simulation results, observations and comments are given.
Numerical computing of elastic homogenized coefficients for periodic fibrous tissue
Directory of Open Access Journals (Sweden)
Roman S.
2009-06-01
Full Text Available The homogenization theory in linear elasticity is applied to a periodic array of cylindrical inclusions in rectangular pattern extending to infinity in the inclusions axial direction, such that the deformation of tissue along this last direction is negligible. In the plane of deformation, the homogenization scheme is based on the average strain energy whereas in the third direction it is based on the average normal stress along this direction. Namely, these average quantities have to be the same on a Repeating Unit Cell (RUC of heterogeneous and homogenized media when using a special form of boundary conditions forming by a periodic part and an affine part of displacement. It exists an infinity of RUCs generating the considered array. The computing procedure is tested with different choices of RUC to control that the results of the homogenization process are independent of the kind of RUC we employ. Then, the dependence of the homogenized coefficients on the microstructure can be studied. For instance, a special anisotropy and the role of the inclusion volume are investigated. In the second part of this work, mechanical traction tests are simulated. We consider two kinds of loading, applying a density of force or imposing a displacement. We test five samples of periodic array containing one, four, sixteen, sixty-four and one hundred of RUCs. The evolution of mean stresses, strains and energy with the numbers of inclusions is studied. Evolutions depend on the kind of loading, but not their limits, which could be predicted by simulating traction test of the homogenized medium.
International Nuclear Information System (INIS)
Bonchev, T.; Statev, S.; Nejkov, Kh.
1980-01-01
A new method of determining the total absorption coefficient applying the Moessbauer effect is proposed. This method enables the accuracy of the measurement increase. The coefficient is measured with practically no background on using the recoilless part of gamma radiation obtained from the Moessbauer source with and without the sample between the source of the gamma-quanta and the detector. Moessbauer sources and absorbers with a single line and without an isomeric shift are used. The recoilless part of the radiation is obtained by the ''two point'' method as a difference between the numbers of photons corresponding to the stationary source and to the vibrating one with a big mean square velocity, respectively. In the concrete measurements the sources 57 Co and 119 Sn are used. The total absorption coefficient for different samples beginning with water up to plumbum is determined. The mean square error for the mean result in all measurements is less than the mean statistical error for the coefficient. The obtained experimental data give a much smaller deviation from the theoretical data of the last issue of the Stom-Israel Tables than the one expected by their authors
Linear attenuation coefficients of tissues from 1 keV to 150 keV
Böke, Aysun
2014-09-01
The linear attenuation coefficients and three interaction processes have been computed for liver, kidney, muscle, fat and for a range of x-ray energies from 1 keV to 150 keV. Molecular photoelectric absorption cross sections were calculated from atomic cross section data. Total coherent (Rayleigh) and incoherent (Compton) scattering cross sections were obtained by numerical integration over combinations of F2m(x) with the Thomson formula and Sm(x) with the Klein-Nishina formula, respectively. For the coherent (Rayleigh) scattering cross section calculations, molecular form factors were obtained from recent experimental data in the literature for values of xelements involved in tissue composition is 5 for liver, 47 for kidney, 44 for muscle and 3 for fat. The results are compared with previously published experimental and theoretical linear attenuation coefficients. In general, good agreement is obtained. The molecular form factors and scattering functions and cross sections are incorporated into a Monte Carlo program. The energy distributions of x-ray photons scattered from tissues have been simulated and the results are presented.
Absorption spectra of adenocarcinoma and squamous cell carcinoma cervical tissues
Ivashko, Pavlo; Peresunko, Olexander; Zelinska, Natalia; Alonova, Marina
2014-08-01
We studied a methods of assessment of a connective tissue of cervix in terms of specific volume of fibrous component and an optical density of staining of connective tissue fibers in the stroma of squamous cancer and cervix adenocarcinoma. An absorption spectra of blood plasma of the patients suffering from squamous cancer and cervix adenocarcinoma both before the surgery and in postsurgical periods were obtained. Linear dichroism measurements transmittance in polarized light at different orientations of the polarization plane relative to the direction of the dominant orientation in the structure of the sample of biotissues of stroma of squamous cancer and cervix adenocarcinoma were carried. Results of the investigation of the tumor tissues showed that the magnitude of the linear dichroism Δ is insignificant in the researched spectral range λ=280-840 nm and specific regularities in its change observed short-wave ranges.
Calvo-Lerma, Joaquim; Martínez-Barona, Sandra; Masip, Etna; Fornés, Victoria; Ribes-Koninckx, Carmen
2017-10-01
Pancreatic enzyme replacement therapy (PERT) remains a backbone in the nutritional treatment of cystic fibrosis. Currently, there is a lack of an evidence-based tool that allows dose adjustment. To date, no studies have found an association between PERT dose and fat absorption. Therefore, the aim of the study was to assess the influence of both the PERT dose and the variability in this dose on the coefficient of fat absorption (CFA). This is a retrospective longitudinal study of 16 pediatric patients (192 food records) with three consecutive visits to the hospital over a twelve-month period. Dietary fat intake and PERT were assessed via a four-day food record and fat content in stools was determined by means of a three-day stool sample collection. A beta regression model was built to explain the association between the CFA and the interaction between the PERT dose (lipase units [LU]/g dietary fat) and the variability in the PERT dose (standard deviation [SD]). The coefficient of fat absorption increased with the PERT dose when the variability in the dose was low. In contrast, even at the highest PERT dose values, the CFA decreased when the variability was high. The confidence interval suggested an association, although the analysis was not statistically significant. The variability in the PERT dose adjustment should be taken into consideration when performing studies on PERT efficiency. A clinical goal should be the maintenance of a constant PERT dose rather than trying to obtain an optimal value.
Empirical formulae for mass attenuation and energy absorption coefficients from 1 keV to 20 MeV
International Nuclear Information System (INIS)
Manjunatha, H.C.; Sowmya, N.; Seenappa, L.; Sridhar, K.N.; Hanumantharayappa, C.
2017-01-01
Mass attenuation and energy absorption coefficients represents attenuation and absorption of X-rays and gamma rays in the material medium. A new empirical formula is proposed for mass attenuation and energy absorption coefficients in the region 1 < Z < 92 and from 1 keV to 20 MeV. The mass attenuation and energy absorption coefficients do not varies linearly with energy. We have performed the nonlinear regressions/nonlinear least square fittings and proposed the simple empirical relations between mass attenuation coefficients (μ/ρ) and mass energy absorption coefficients (μ en /ρ) and energy. We have compared the values produced by this formula with that of experiments. A good agreement of present formula with the experiments/previous models suggests that the present formulae could be used to evaluate mass attenuation and energy absorption coefficients in the region 1 < Z < 92. This formula is a model-independent formula and is the first of its kind that produces a mass attenuation and energy absorption coefficient values with the only simple input of energy for wide energy range 1 keV - 20 MeV in the atomic number region 1 < Z < 92. This formula is very much useful in the fields of radiation physics and dosimetry
Functional dependence of the lower hybrid power absorption coefficient in JET
International Nuclear Information System (INIS)
Pericoli-Ridolfini, V.; Ekedahl, A.; Baranov, Y.
1997-01-01
The fraction of the coupled lower hybrid (LH) power adsorbed in divertor plasmas in JET has been determined experimentally with a method utilizing the time derivative of the total stored energy (plasma and magnetic). This method can account for the power adsorbed inside a normalized flux co-ordinate ψ ∼ 0.7. The experimental LH absorption coefficient reaches 100% at low plasma densities, antineutron e 19 m -3 and decreases to 25% at antineutron e > 3.5 x 10 19 m -3 . The LH wave accessibility to the plasma core has been found to play an important role in determining the power absorption and the radial deposition profile. The decreasing absorption is correlated with a gradual shift of the LH power deposition profile, as determined by the hard x-ray profiles, towards the plasma periphery. Similar behaviour is found in ray tracing + Fokker-Planck code calculations. The frequency spectrum of the LH pump wave as determined by a probe outside the tokamak vessel broadens strongly as the wave accessibility is reduced and the absorption drops. (author)
International Nuclear Information System (INIS)
Kieser, R.; Mulligan, T.J.
1979-01-01
An equation is developed which describes the X-ray scatter radiation from specimens of any thickness. This equation suggests that a specimen's mass absorption coefficient can be determined from its inelastically scattered X-radiation not only when the specimen is 'infinitely thick' but also when it is of 'intermediate thickness'. Measurements have been carried out with a standard energy-dispersive X-ray spectrometer on specimens of 'intermediate thickness'. Good agreement is obtained between the mass absorption coefficients that are calculated from the scattered radiation and those obtained on the basis of tabulated mass absorption coefficients for the elements. (author)
Pressure-induced absorption coefficients for radiative transfer calculations in Titan's atmosphere
Courtin, Regis
1988-01-01
The semiempirical theory of Birnbaum and Cohen (1976) is used to calculate the FIR pressure-induced absorption (PIA) spectra of N2, CH4, N2 + Ar, N2 + CH4, and N2 + H2 under conditions like those in the Titan troposphere. The results are presented graphically and compared with published data from laboratory measurements of PIA in the same gases and mixtures (Dagg et al., 1986; Dore et al., 1986). Good agreement is obtained, with only a slight underestimation of PIA at 300-400/cm in the case of CH4. The absorption coefficients are presented in tables, and it is suggested that the present findings are of value for evaluating the effects of tropospheric clouds on the Titan FIR spectrum and studying the greenhouse effect near the Titan surface.
Measurement of mass attenuation coefficients around the K absorption edge by parametric X-rays
International Nuclear Information System (INIS)
Tamura, Masaya; Akimoto, Tadashi; Aoki, Yohei; Ikeda, Jiro; Sato, Koichi; Fujita, Fumiyuki; Homma, Akira; Sawamura, Teruko; Narita, Masakuni
2002-01-01
When electrons at relativistic velocities pass through a crystal plate, such as silicon, photons are emitted around the Bragg angle for X-ray diffraction. This phenomenon is called parametric X-ray radiation (PXR). The monochromaticity and directivity of PXR are adequate and the energy can be changed continuously by rotating the crystal. This study measured the mass attenuation coefficient around the K-shell absorption edge of Nb, Zr and Mo as a PXR application of monochromatic hard X-ray radiation sources
Measurement of mass attenuation coefficients around the K absorption edge by parametric X-rays
Tamura, M; Aoki, Y; Ikeda, J; Sato, K; Fujita, F; Homma, A; Sawamura, T; Narita, M
2002-01-01
When electrons at relativistic velocities pass through a crystal plate, such as silicon, photons are emitted around the Bragg angle for X-ray diffraction. This phenomenon is called parametric X-ray radiation (PXR). The monochromaticity and directivity of PXR are adequate and the energy can be changed continuously by rotating the crystal. This study measured the mass attenuation coefficient around the K-shell absorption edge of Nb, Zr and Mo as a PXR application of monochromatic hard X-ray radiation sources.
Modeling microwave electromagnetic field absorption in muscle tissues
Felbacq, D.; Clerjon, S.; Damez, J. L.; Zolla, F.
2002-07-01
Absorption of electromagnetic energy in human tissues is an important issue with respect to the safety of low-level exposure. Simulation is a way to a better understanding of electromagnetic dosimetry. This letter presents a comparison between results obtained from a numerical simulation and experimental data of absorbed energy by a muscle. Simulation was done using a bidimensional double-scale homogenization scheme leading to the effective permittivity tensor. Experimental measurements were performed at 10 GHz on bovine muscle, 30 hours after slaughter, thanks to the open-ended rectangular waveguide method. Results show a good agreement between measurements and simulated data.
National Oceanic and Atmospheric Administration, Department of Commerce — The Sea surface topography, absorption, scattering, attenuation coefficients and other data in this accession was collected from NOAA-11 Advanced Very High...
DEFF Research Database (Denmark)
Jeong, Cheol-Ho; Choi, Sang-Hyeon; Lee, Ikjin
2017-01-01
A Bayesian analysis is applied to determine the flow resistivity of a porous sample and the influence of the test chamber based on measured Sabine absorption coefficient data. The Sabine absorption coefficient measured in a reverberation chamber according to ISO 354 is influenced by the test...... chamber significantly, whereas the flow resistivity is a rather reproducible material property, from which the absorptive characteristics can be calculated through reliable models. Using Sabine absorption coefficients measured in 13 European reverberation chambers, the maximum a posteriori...... and the uncertainty of the flow resistivity and the test chamber’s influence are estimated. Inclusion of more than one chamber’s absorption data helps the flow resistivity converge towards a reliable value with a standard deviation below 17%...
DEFF Research Database (Denmark)
Jelnes, R; Astrup, A
1985-01-01
131Iodo-antipyrine (131I-AP) is commonly used for blood flow measurements in adipose tissue. These estimations have been based on the assumption of the tissue-to-blood partition coefficient being 1 ml g-1. No exact determination of the tissue-to-blood partition coefficient for 131I-AP in adipose...... tissue has been carried out. In the present study a partition coefficient of 1.12 +/- 0.06 (mean +/- S.D.) for 131I-AP in adipose tissue has been determined based on the partition coefficient for 131I-AP between lipid-saline (1.24 ml g-1), red blood cells-plasma (0.64 ml g-1), protein-saline (0.19 ml g-1...
Determination of absorption coefficient based on laser beam thermal blooming in gas-filled tube.
Hafizi, B; Peñano, J; Fischer, R; DiComo, G; Ting, A
2014-08-01
Thermal blooming of a laser beam propagating in a gas-filled tube is investigated both analytically and experimentally. A self-consistent formulation taking into account heating of the gas and the resultant laser beam spreading (including diffraction) is presented. The heat equation is used to determine the temperature variation while the paraxial wave equation is solved in the eikonal approximation to determine the temporal and spatial variation of the Gaussian laser spot radius, Gouy phase (longitudinal phase delay), and wavefront curvature. The analysis is benchmarked against a thermal blooming experiment in the literature using a CO₂ laser beam propagating in a tube filled with air and propane. New experimental results are presented in which a CW fiber laser (1 μm) propagates in a tube filled with nitrogen and water vapor. By matching laboratory and theoretical results, the absorption coefficient of water vapor is found to agree with calculations using MODTRAN (the MODerate-resolution atmospheric TRANsmission molecular absorption database) and HITRAN (the HIgh-resolution atmospheric TRANsmission molecular absorption database).
Carbonation Coefficients from Concrete Made with High-Absorption Limestone Aggregate
Directory of Open Access Journals (Sweden)
Eric I. Moreno
2013-01-01
Full Text Available Normal aggregates employed in concrete have absorption levels in the range of 0.2% to 4% for coarse aggregate and 0.2 to 2% for fine aggregate. However, some aggregates have absorption levels above these values. As the porosity of concrete is related to the porosity of both the cement paste and the aggregate and the carbonation rate is a function, among other things, of the porosity of the material, there is concern about the effect of this high porosity material in achieving good quality concrete from the durability point of view. Thus, the objective of this investigation was to study the carbonation rates of concrete specimens made with high-absorption limestone aggregate. Four different water/cement ratios were used, and cylindrical concrete specimens were exposed to accelerated carbonation. High porosity values were obtained for concrete specimens beyond the expected limits for durable concrete. However, carbonation coefficients related to normal quality concrete were obtained for the lowest water/cement ratio employed suggesting that durable concrete may be obtained with this material despite the high porosity.
Directory of Open Access Journals (Sweden)
Joaquim Calvo-Lerma
Full Text Available Objectives: Pancreatic enzyme replacement therapy (PERT remains a backbone in the nutritional treatment of cystic fibrosis. Currently, there is a lack of an evidence-based tool that allows dose adjustment. To date, no studies have found an association between PERT dose and fat absorption. Therefore, the aim of the study was to assess the influence of both the PERT dose and the variability in this dose on the coefficient of fat absorption (CFA. Methods: This is a retrospective longitudinal study of 16 pediatric patients (192 food records with three consecutive visits to the hospital over a twelve-month period. Dietary fat intake and PERT were assessed via a four-day food record and fat content in stools was determined by means of a three-day stool sample collection. A beta regression model was built to explain the association between the CFA and the interaction between the PERT dose (lipase units [LU]/g dietary fat and the variability in the PERT dose (standard deviation [SD]. Results: The coefficient of fat absorption increased with the PERT dose when the variability in the dose was low. In contrast, even at the highest PERT dose values, the CFA decreased when the variability was high. The confidence interval suggested an association, although the analysis was not statistically significant. Conclusion: The variability in the PERT dose adjustment should be taken into consideration when performing studies on PERT efficiency. A clinical goal should be the maintenance of a constant PERT dose rather than trying to obtain an optimal value.
Hoche, S; Hussein, M A; Becker, T
2015-03-01
The accuracy of density, reflection coefficient, and acoustic impedance determination via multiple reflection method was validated experimentally. The ternary system water-maltose-ethanol was used to execute a systematic, temperature dependent study over a wide range of densities and viscosities aiming an application as inline sensor in beverage industries. The validation results of the presented method and setup show root mean square errors of: 1.201E-3 g cm(-3) (±0.12%) density, 0.515E-3 (0.15%) reflection coefficient and 1.851E+3 kg s(-1) m(-2) (0.12%) specific acoustic impedance. The results of the diffraction corrected absorption showed an average standard deviation of only 0.12%. It was found that the absorption change shows a good correlation to concentration variations and may be useful for laboratory analysis of sufficiently pure liquids. The main part of the observed errors can be explained by the observed noise, temperature variation and the low signal resolution of 50 MHz. In particular, the poor signal-to-noise ratio of the second reflector echo was found to be a main accuracy limitation. Concerning the investigation of liquids the unstable properties of the reference material PMMA, due to hygroscopicity, were identified to be an additional, unpredictable source of uncertainty. While dimensional changes can be considered by adequate methodology, the impact of the time and temperature dependent water absorption on relevant reference properties like the buffer's sound velocity and density could not be considered and may explain part of the observed deviations. Copyright © 2014 Elsevier B.V. All rights reserved.
Liu, Peipei; Zhu, Zhirong; Zeng, Changchun; Nie, Guang
2012-12-01
Hemoglobin (Hb), as one of main components of blood, has a unique quaternary structure. Its release of oxygen is controlled by oxygen partial pressure (PO2). We investigate the specific spectroscopic changes in Hb under different PO2 levels to optimize clinical methods of measuring tissue PO2. The transmissivity of Hb under different PO2 levels is measured with a UV/Vis fiber optic spectrometer. Its plotted absorption spectral curve shows two high absorption peaks at 540 and 576 nm and an absorption valley at 560 nm when PO2 is higher than 100 mm Hg. The two high absorption peaks decrease gradually with a decrease in PO2, whereas the absorption valley at 560 nm increases. When PO2 decreases to approximately 0 mm Hg, the two high absorption peaks disappear completely, while the absorption valley has a hypochromic shift (8 to 10 nm) and forms a specific high absorption peak at approximately 550 nm. The same phenomena can be observed in visible reflectance spectra of finger-tip microcirculation. Specific changes in extinction coefficient and absorption spectra of Hb occur along with variations in PO2, which could be used to explain pathological changes caused by tissue hypoxia and for early detection of oxygen deficiency diseases in clinical monitoring.
Directory of Open Access Journals (Sweden)
Seyyedeh Maliheh Mirhashemi
2015-10-01
Full Text Available Leaf area index, light extinction coefficient and radiation use efficiency are important eco-physiological characteristics for realization of crops growth, development and radiation absorption. In order to determine the leaf area index (LAI, light extinction coefficient (K and radiation use efficiency (RUE of saffron during the first and second growing seasons, four experiments were started in 2011 and ended in 2014, at the Research Farm of the Agriculture Faculty, the Ferdowsi University of Mashhad, Iran. Saffron corms with weights between 13 to15 g and density of 50 plant.m2 were cultivated in 2011 and 2012. In all experimental years during the growing season, crop sampling was taken for required measurements including the leaf area index and shoot dry weight of saffron once every 14 days. The results showed that by increasing the age of saffron from 1 year to two years, the maximum LAI of saffron increased from 0.33 to 1.81, and light extinction coefficient decreased from 1.20 to 0.54. The increasing trend of LAI was coincident with fraction of absorbed radiation for all four years of the experiment. In the first and the second growing seasons, the amount of fraction of absorbed radiation gradually increased with increasing LAI and at 1083 and 1034 GDD reached its maximum value, respectively. In saffron farms when the plant was one year old and two years old, the mean value of RUE was 0.68 and 1.73 g.MJ-1 PAR, respectively. These results indicate that by increasing the saffron age and LAI, the value of K decreases and consequently radiation absorption and use efficiency will increase.
Sound absorption coefficient in situ: an alternative for estimating soil loss factors.
Freire, Rosane; Meletti de Abreu, Marco Henrique; Okada, Rafael Yuri; Soares, Paulo Fernando; GranhenTavares, Célia Regina
2015-01-01
The relationship between the sound absorption coefficient and factors of the Universal Soil Loss Equation (USLE) was determined in a section of the Maringá Stream basin, Paraná State, by using erosion plots. In the field, four erosion plots were built on a reduced scale, with dimensions of 2.0×12.5m. With respect to plot coverage, one was kept with bare soil and the others contained forage grass (Brachiaria), corn and wheat crops, respectively. Planting was performed without any type of conservation practice in an area with a 9% slope. A sedimentation tank was placed at the end of each plot to collect the material transported. For the acoustic system, pink noise was used in the measurement of the proposed monitoring, for collecting information on incident and reflected sound pressure levels. In general, obtained values of soil loss confirmed that 94.3% of material exported to the basin water came from the bare soil plot, 2.8% from the corn plot, 1.8% from the wheat plot, and 1.1% from the forage grass plot. With respect to the acoustic monitoring, results indicated that at 16kHz erosion plot coverage type had a significant influence on the sound absorption coefficient. High correlation coefficients were found in estimations of the A and C factors of the USLE, confirming that the acoustic technique is feasible for the determination of soil loss directly in the field. Copyright © 2014 Elsevier B.V. All rights reserved.
DEFF Research Database (Denmark)
Stæhr, P. A.; Markager, S.
2004-01-01
We evaluated models predicting the spectral chlorophyll-a (Chl a)-specific absorption coefficient (a*ph (¿)) from Chl a concentration [Chl a] on the basis of 465 phytoplankton absorption spectra collected in estuarine, coastal and oceanic waters. A power model on ln-transformed data provided...
Eldridge, Jeffrey I.; Spuckler, Charles M.; Markham, James R.
2009-01-01
The temperature dependence of the scattering and absorption coefficients for a set of freestanding plasma-sprayed 8 wt% yttria-stabilized zirconia (8YSZ) thermal barrier coatings (TBCs) was determined at temperatures up to 1360 C in a wavelength range from 1.2 micrometers up to the 8YSZ absorption edge. The scattering and absorption coefficients were determined by fitting the directional-hemispherical reflectance and transmittance values calculated by a four-flux Kubelka Munk method to the experimentally measured hemispherical-directional reflectance and transmittance values obtained for five 8YSZ thicknesses. The scattering coefficient exhibited a continuous decrease with increasing wavelength and showed no significant temperature dependence. The scattering is primarily attributed to the relatively temperature-insensitive refractive index mismatch between the 8YSZ and its internal voids. The absorption coefficient was very low (less than 1 per centimeter) at wavelengths between 2 micrometers and the absorption edge and showed a definite temperature dependence that consisted of a shift of the absorption edge to shorter wavelengths and an increase in the weak absorption below the absorption edge with increasing temperature. The shift in the absorption edge with temperature is attributed to strongly temperature-dependent multiphonon absorption. While TBC hemispherical transmittance beyond the absorption edge can be predicted by a simple exponential decrease with thickness, below the absorption edge, typical TBC thicknesses are well below the thickness range where a simple exponential decrease in hemispherical transmittance with TBC thickness is expected. [Correction added after online publication August 11, 2009: "edge to a shorter wavelengths" has been updated as edge to shorter wavelengths."
IR Absorption Coefficients for the Quantification of Water in Hydrous Ringwoodite
Thomas, Sylvia-Monique; Jacobsen, Steven D.; Bina, Craig R.; Smyth, Joseph R.; Frost, Daniel J.
2010-05-01
Raman spectroscopy, combined with the 'Comparator technique' has been developed to determine water contents ranging from a few wt ppm to wt% in glasses and nominally anhydrous minerals including garnets, olivine, and SiO2 polymorphs (Thomas et al. 2009). The routine is one promising example of quantification tools to determine mineral specific molar absorption coefficients (ɛ) for IR spectroscopy. Mineral specific absorption coefficients are required because general IR calibrations do not necessarily apply to minerals with water incorporated as hydroxyl point defects. Here we utilize the 'Comparator technique' to provide ɛ-values for a set of synthetic Fe-free (Fo100) and Fe-bearing (Fo90, Fo87, Fo83, Fo60) ringwoodites, as well as for γ-Mg2GeO4. Ringwoodite is considered one of the major phases of the Earth's lower transition zone (520-660 km depth) and the knowledge of its absolute water storage capacity is essential for modeling the Earth's deep water cycle. Samples were synthesized at variable P-T conditions in a multi-anvil press and cover a range of OH contents. Single-crystals were characterized using X-ray diffraction and IR spectroscopy. Mineral specific IR absorption coefficients were calculated from independently determined water contents from Raman spectroscopy. Unpolarized IR spectra of Mg-ringwoodite show broad absorption features in the OH region with band maxima at ~2350, 2538, 3130, 3172, 3598 and 3688 cm-1. In the spectra of Fe-bearing ringwoodite and γ-Mg2GeO4 the maxima of the main OH band are shifted to 3244 cm-1 (Fo60) and 3207 cm-1, respectively. For Mg-ringwoodite with the mean wavenumber (area-weighted average of the peak position) of 3170 cm-1 an ɛ-value of 191500 ± 38300 L cm-2/ molH2O was determined. For the ringwoodites with Fo90, Fo87 and Fo83 composition and the mean wavenumbers of 3229 cm-1, 3252 cm-1 and 3163 cm-1 values of 123600 ± 24700 L cm-2/ molH2O, 176300 ± 52900 L cm-2/ molH2O and 155000 ± 46500 L cm-2/ molH2O were
Energy Technology Data Exchange (ETDEWEB)
Joffre, H; Pages, L [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires
1968-07-01
In this report are given the elements allowing the definition of the values of mass attenuation coefficients and mass energy absorption coefficients for some elements and mixtures, necessary for the study of tissue equivalent materials, for photons in the energy range 10 keV to 10 MeV. After a short reminding of the definitions of the two coefficients, follows, in table form, a compilation of these coefficients, as a function of energy, for simple elements, for certain mineral compounds, organic compounds, gases and particularly of soft tissues. (author) [French] Dans ce rapport, sont donnes les elements permettant de determiner les valeurs des coefficients d'attenuation massique et d'absorption massique en energie pour certains elements et melanges necessaires a l'etude des materiaux equivalents aux tissus pour les photons dans le domaine d'energie allant de 10 keV a 10 MeV. Apres un bref rappel des definitions des deux coefficients, suit, sous forme de tableaux, un recueil de ces coefficients, en fonction de l'energie, pour les elements simples, certains composes mineraux, composes organiques, gaz, et, particulierement, pour les tissus mous. (auteur)
The Optical Absorption Coefficient of Maize Grains Investigated by Photoacoustic Spectroscopy
Rodríguez-Páez, C. L.; Carballo-Carballo, A.; Rico-Molina, R.; Hernández-Aguilar, C.; Domínguez-Pacheco, A.; Cruz-Orea, A.; Moreno-Martínez, E.
2017-01-01
In the maize and tortilla industry, it is important to characterize the color of maize ( Zea mays L.) grain, as it is one of the attributes that directly affect the quality of the tortillas consumed by the population. For this reason, the availability of alternative techniques for assessing and improving the quality of grain is valued. Photoacoustic spectroscopy has proven to be a useful tool for characterizing maize grain. So, the objective of the present study was to determine the optical absorption coefficient β of the maize grain used to make tortillas from two regions of Mexico: (a) Valles Altos, 2012-2013 production cycle and (b) Guasave, Sinaloa, 2013-2014 production cycle. Traditional reflectance measurements, physical characteristics of the grain and nutrient content were also calculated. The experimental results show different characteristics for maize grains.
Coefficient of Performance Optimization of Single-Effect Lithium-Bromide Absorption Cycle Heat Pumps
DEFF Research Database (Denmark)
Vinther, Kasper; Just Nielsen, Rene; Nielsen, Kirsten Mølgaard
2015-01-01
In this paper, we investigate the coefficient of performance (COP) of a LiBr absorption cycle heat pump under different operating conditions. The investigation is carried out using a dynamical model fitted against data recorded from an actual heat pump used for district heating in S......⊘nderborg, Denmark. Since the model is too complex to study analytically, we vary different input variables within the permissible operating range of the heat pump and evaluate COP at the resulting steady-state operating points. It is found that the best set-point for each individual input is located at an extreme......-state operation of the heat pump, while avoiding crystallization issues....
Modeling of light absorption in tissue during infrared neural stimulation
Thompson, Alexander C.; Wade, Scott A.; Brown, William G. A.; Stoddart, Paul R.
2012-07-01
A Monte Carlo model has been developed to simulate light transport and absorption in neural tissue during infrared neural stimulation (INS). A range of fiber core sizes and numerical apertures are compared illustrating the advantages of using simulations when designing a light delivery system. A range of wavelengths, commonly used for INS, are also compared for stimulation of nerves in the cochlea, in terms of both the energy absorbed and the change in temperature due to a laser pulse. Modeling suggests that a fiber with core diameter of 200 μm and NA=0.22 is optimal for optical stimulation in the geometry used and that temperature rises in the spiral ganglion neurons are as low as 0.1°C. The results show a need for more careful experimentation to allow different proposed mechanisms of INS to be distinguished.
Dall'Olmo, Giorgio; Brewin, Robert J W; Nencioli, Francesco; Organelli, Emanuele; Lefering, Ina; McKee, David; Röttgers, Rüdiger; Mitchell, Catherine; Boss, Emmanuel; Bricaud, Annick; Tilstone, Gavin
2017-11-27
Measurements of the absorption coefficient of chromophoric dissolved organic matter (ay) are needed to validate existing ocean-color algorithms. In the surface open ocean, these measurements are challenging because of low ay values. Yet, existing global datasets demonstrate that ay could contribute between 30% to 50% of the total absorption budget in the 400-450 nm spectral range, thus making accurate measurement of ay essential to constrain these uncertainties. In this study, we present a simple way of determining ay using a commercially-available in-situ spectrophotometer operated in underway mode. The obtained ay values were validated using independent collocated measurements. The method is simple to implement, can provide measurements with very high spatio-temporal resolution, and has an accuracy of about 0.0004 m -1 and a precision of about 0.0025 m -1 when compared to independent data (at 440 nm). The only limitation for using this method at sea is that it relies on the availability of relatively large volumes of ultrapure water. Despite this limitation, the method can deliver the ay data needed for validating and assessing uncertainties in ocean-colour algorithms.
Realistic absorption coefficient of each individual film in a multilayer architecture
Cesaria, M.; Caricato, A. P.; Martino, M.
2015-02-01
A spectrophotometric strategy, termed multilayer-method (ML-method), is presented and discussed to realistically calculate the absorption coefficient of each individual layer embedded in multilayer architectures without reverse engineering, numerical refinements and assumptions about the layer homogeneity and thickness. The strategy extends in a non-straightforward way a consolidated route, already published by the authors and here termed basic-method, able to accurately characterize an absorbing film covering transparent substrates. The ML-method inherently accounts for non-measurable contribution of the interfaces (including multiple reflections), describes the specific film structure as determined by the multilayer architecture and used deposition approach and parameters, exploits simple mathematics, and has wide range of applicability (high-to-weak absorption regions, thick-to-ultrathin films). Reliability tests are performed on films and multilayers based on a well-known material (indium tin oxide) by deliberately changing the film structural quality through doping, thickness-tuning and underlying supporting-film. Results are found consistent with information obtained by standard (optical and structural) analysis, the basic-method and band gap values reported in the literature. The discussed example-applications demonstrate the ability of the ML-method to overcome the drawbacks commonly limiting an accurate description of multilayer architectures.
[Estimation of DOC concentrations using CDOM absorption coefficients: a case study in Taihu Lake].
Jiang, Guang-Jia; Ma, Rong-Hua; Duan, Hong-Tao
2012-07-01
Dissolved organic carbon (DOC) is the largest organic carbon stock in water ecosystems, which plays an important role in the carbon cycle in water. Chromophoric dissolved organic matter (CDOM), an important water color variation, is the colored fraction of DOC and its absorption controls the instruction of light under water. The available linkage between DOC concentration and CDOM absorptions enables the determination of DOC accumulations using remote sensing reflectance or radiance in lake waters. The present study explored the multi-liner relationship between CDOM absorptions [a(g) (250) and a(g) (365)] and DOC concentrations in Taihu Lake, based on the available data in 4 cruises (201005, 201101, 201103, 201105) (totally 183 sampling sites). Meanwhile, the results were validated with the data of the experiment carried out from August 29 to September 2, 2011 in Taihu Lake (n = 27). Furthermore, a universal pattern of modeling from remote sensing was built for lake waters. The results demonstrated that this method provided more satisfying estimation of DOC concentrations in Taihu Lake. Except the data obtained in January 2011, the fitted results of which were not conductive to the winter dataset (201101) in Taihu Lake, due to the diverse sources and sinks of DOC and CDOM, the multi-liner relationship was robust for the data collected in the other three cruises (R2 = 0.64, RMSE = 14.31%, n = 164), which was validated using the 201108 sampling dataset (R2 = 0.67, RMSE = 10.58%, n = 27). In addition, the form of the statistic model is universal, to some extent, for other water areas, however, there is difference in the modeling coefficients. Further research should be focused on the parameterization using local data from different lakes, which provides effective methodology for the estimation of DOC concentrations in lakes and other water regions.
International Nuclear Information System (INIS)
Shaltout, A.
2003-06-01
The present work describes some actual problems of quantitative x-ray fluorescence analysis by means of the fundamental parameter approach. To perform this task, some of the main parameters are discussed in detail. These parameters are photoelectric cross sections, coherent and incoherent scattering cross sections, mass absorption cross sections and the variation of the x-ray tube voltage. Photoelectric cross sections, coherent and incoherent scattering cross sections and mass absorption cross sections in the energy range from 1 to 300 keV for the elements from Z=1 to 94 considering ten different data bases are studied. These are data bases given by Hubbell, McMaster, Mucall, Scofield, Xcom, Elam, Sasaki, Henke, Cullen and Chantler's data bases. These data bases have been developed also for an application in fundamental parameter programs for quantitative x-ray analysis (Energy Dispersive X-Ray Fluorescence Analysis (EDXRFA), Electron Probe Microanalysis (EPMA), X-Ray Photoelectron Spectroscopy (XPS) and Total Electron Yield (TEY)). In addition a comparison is performed between different data bases. In McMaster's data base, the missing elements (Z=84, 85, 87, 88, 89, 91, and 93) are added by using photoelectric cross sections of Scofield's data base, coherent as well as incoherent scattering cross sections of Elam's data base and the absorption edges of Bearden. Also, the N-fit coefficients of the elements from Z=61 to 69 are wrong in McMaster data base, therefore, linear least squares fits are used to recalculate the N-fit coefficients of these elements. Additionally, in the McMaster tables the positions of the M- and N-edges of all elements with the exception of the M1- and N1- edges are not defined as well as the jump ratio of the edges. In the present work, the M- and N-edges and the related jump ratios are calculated. To include the missing N-edges, Bearden's values of energy edges are used. In Scofield's data base, modifications include check and correction
Measuring principles of frictional coefficients in cartilaginous tissues and its substitutes
Huyghe, J.M.R.J.; Janssen, C.F.; Donkelaar, van C.C.; Lanir, Y.
2002-01-01
The frictional properties of cartilaginous tissues, such as the hydraulic permeability, the electro-osmotic permeability, the diffusion coefficients of various ions and solutes, and the electrical conductance, are vital data to characterise the extracellular environment in which chondrocytes reside.
Solid tissue simulating phantoms having absorption at 970 nm for diffuse optics
Kennedy, Gordon T.; Lentsch, Griffin R.; Trieu, Brandon; Ponticorvo, Adrien; Saager, Rolf B.; Durkin, Anthony J.
2017-07-01
Tissue simulating phantoms can provide a valuable platform for quantitative evaluation of the performance of diffuse optical devices. While solid phantoms have been developed for applications related to characterizing exogenous fluorescence and intrinsic chromophores such as hemoglobin and melanin, we report the development of a poly(dimethylsiloxane) (PDMS) tissue phantom that mimics the spectral characteristics of tissue water. We have developed these phantoms to mimic different water fractions in tissue, with the purpose of testing new devices within the context of clinical applications such as burn wound triage. Compared to liquid phantoms, cured PDMS phantoms are easier to transport and use and have a longer usable life than gelatin-based phantoms. As silicone is hydrophobic, 9606 dye was used to mimic the optical absorption feature of water in the vicinity of 970 nm. Scattering properties are determined by adding titanium dioxide, which yields a wavelength-dependent scattering coefficient similar to that observed in tissue in the near-infrared. Phantom properties were characterized and validated using the techniques of inverse adding-doubling and spatial frequency domain imaging. Results presented here demonstrate that we can fabricate solid phantoms that can be used to simulate different water fractions.
International Nuclear Information System (INIS)
Wang, Li; Eldridge, Jeffrey I.; Guo, S.M.
2014-01-01
The thermal radiative properties of thermal barrier coatings (TBCs) are becoming more important as the inlet temperatures of advanced gas-turbine engines are continuously being pushed higher in order to improve efficiency. To determine the absorption and scattering coefficients of TBCs, four-flux, two-flux and Kubelka–Munk models were introduced and used to characterize the thermal radiative properties of plasma-sprayed yttria-stabilized zirconia (YSZ) coatings. The results show that the absorption coefficient of YSZ is extremely low for wavelengths 200 μm suggests that when the coating thickness is larger than around twice the average scattering distance, the collimated flux can be simply treated as a diffuse flux inside the coating, and thus the two-flux model can be used to determine the absorption and scattering coefficients as a simplification of the four-flux model
International Nuclear Information System (INIS)
Jaeger, Marion; Kienle, Alwin
2011-01-01
We investigated the performance of a neural network for derivation of the absorption coefficient of the brain from simulated non-invasive time-resolved reflectance measurements on the head. A five-layered geometry was considered assuming that the optical properties (except the absorption coefficient of the brain) and the thickness of all layers were known with an uncertainty. A solution of the layered diffusion equation was used to train the neural network. We determined the absorption coefficient of the brain with an RMS error of <6% from reflectance data at a single distance calculated by diffusion theory. By applying the neural network to reflectance curves obtained from Monte Carlo simulations, similar errors were found. (note)
Energy Technology Data Exchange (ETDEWEB)
Ozser, Mustafa E. [Girne American University, Faculty of Engineering and Architecture, Department of Industrial Engineering, Girne, North Cyprus (Cyprus); Yucekan, Ilke; Bodapati, Jagadeesh B. [Eastern Mediterranean University, Faculty of Arts and Sciences, Department of Chemistry, Famagusta, North Cyprus (Cyprus); Icil, Huriye, E-mail: huriye.icil@emu.edu.tr [Eastern Mediterranean University, Faculty of Arts and Sciences, Department of Chemistry, Famagusta, North Cyprus (Cyprus)
2013-11-15
A high molecular weight 1,4,5,8-naphthalene polyimide (ENPI) by one-step polycondensation mechanism and for comparison its monomeric diimide (ENDI) were synthesized; the photophysical and electrochemical properties were studied in detail for ENPI. Monomer has shown unusual insolubility so that the characterization proven to be difficult, whereas ENPI has shown better solubility. The molecular weight data obtained by GPC for the polymer were M{sub n}=8240 and M{sub w}=34,000 g mol{sup −1} respectively with a polydispersity of 4.13. The polyimide exhibited outstandingly high molar absorption coefficients as 599,000, 1,021,000, and 972,700 M{sup −1} cm{sup −1}, which is first time reported in literature for the characteristic 0–2, 0–1, and 0–0 electronic transitions, respectively. ENPI showed concentration dependent and red shifted excimer emission in 1,1,2,2-tetrachloroethane (TCE). The polymer has undergone multielectron reductions in CHCl{sub 3} solution below 100 mV s{sup −1} scan rates which merged into two reversible one-electron reduction peaks at higher scan rates. In solid-state, similar scan rate dependent reduction peaks were noticed. The LUMO, HOMO and optical band gap values obtained for ENPI were −3.73, −6.91, and 3.18 eV respectively. ENDI polymer with striking features has great potential as new sensitizer for efficient dye sensitized organic cells. Highlights: • A high molecular weight naphthalene polyimide was synthesized (M{sub w}=34,000 g mol{sup −1}). • The oligoether polyimide exhibited outstanding molar absorptivity (972,700 M{sup −1} cm{sup −1}). • A red shifted excimer emission has been observed. • The polymer has undergone multielectron reductions.
The influence of surface modification on sound absorption coefficient of albizzia wood absorber
Diharjo, Kuncoro; Prabowo, Anditya E.; Jamasri, Suharty, Neng Sri
2017-01-01
The purpose of this research is to investigate the influence of surface modification to sound absorption on absorber based albizia wood and kenaf fiber. The absorber was produced using the albizia wood as main materials, and the kenaf fiber was used as acoustic fill. The albizia wood used for producing the absorber was cut in the transverse direction so that its surface had good porosity. The size of specimens had 100 mm in diameter and 40 mm in thickness. The configuration of resonator cavities was 30 mm in diameter and 20 mm in depth, and each resonator was completed with a neck hole of the resonator. The types of surface modification were the addition of screen printing ink, fabric (with and without neck hole), and vinyl-wallpaper (with and without neck hole). According to ISO 10534-2, the absorber specimens were tested using two microphones impedance tube with random noise source to get the curve of noise absorption coefficient (NAC) for each specimen. The result shows that both unmodified absorber and absorber modified with screen printing ink have the similar characteristic of NAC and they are feasible to be used as an absorber in conversation rooms. The addition of fabric and vinyl-wallpaper as cover on the absorber surface give the positive effect of the air gap, and it increases the NAC in low frequency (100-400 Hz). However, the covers decrease the NAC in high frequency (400-1,400 Hz). The holes on the fabric and wallpaper covers give the improvement of NAC.
Absorption, tissue distribution, excretion, and metabolism of clothianidin in rats.
Yokota, Tokunori; Mikata, Kazuki; Nagasaki, Hiromi; Ohta, Kazunari
2003-11-19
Absorption, distribution, excretion, and metabolism of clothianidin [(E)-1-(2-chloro-1,3-thiazol-5-ylmethyl)-3-methyl-2-nitroguanidine] were investigated after a single oral administration of [nitroimino-(14)C]- or [thiazolyl-2-(14)C]clothianidin to male and female rats at a dose of 5 mg/kg of body weight (bw) (low dose) or 250 mg/kg of bw (high dose). The maximum concentration of carbon-14 in blood occurred 2 h after administration of the low oral dose for both labeled clothianidins, and then the concentration of carbon-14 in blood decreased with a half-life of 2.9-4.0 h. The orally administered carbon-14 was rapidly and extensively distributed to all tissues and organs within 2 h after administration, especially to the kidney and liver, but was rapidly and almost completely eliminated from all tissues and organs with no evidence of accumulation. The orally administered carbon-14 was almost completely excreted into urine and feces within 2 days after administration, and approximately 90% of the administered dose was excreted via urine. The major compound in excreta was clothianidin, accounting for >60% of the administered dose. The major metabolic reactions of clothianidin in rats were oxidative demethylation to form N-(2-chlorothiazol-5-ylmethyl)-N'-nitroguanidine and the cleavage of the carbon-nitrogen bond between the thiazolylmethyl moiety and the nitroguanidine moiety. The part of the molecule containing the nitroguanidine moiety was transformed mainly to N-methyl-N'-nitroguanidine, whereas the thiazol moiety was further metabolized to 2-(methylthio)thiazole-5-carboxylic acid. With the exception of the transiently delayed excretion of carbon-14 at the high-dose level, the rates of biokinetics, excretion, distribution, and metabolism of clothianidin were not markedly influenced by dose level and sex.
International Nuclear Information System (INIS)
Artursson, P.; Karlsson, J.
1991-01-01
Monolayers of a well differentiated human intestinal epithelial cell line, Caco-2, were used as a model to study passive drug absorption across the intestinal epithelium. Absorption rate constants (expressed as apparent permeability coefficients) were determined for 20 drugs and peptides with different structural properties. The permeability coefficients ranged from approximately 5 x 10 - 8 to 5 x 10 - 5 cm/s. A good correlation was obtained between data on oral absorption in humans and the results in the Caco-2 model. Drugs that are completely absorbed in humans had permeability coefficients greater than 1 x 10 - 6 cm/s. Drugs that are absorbed to greater than 1% but less than 100% had permeability coefficients of 0.1-1.0 x 10 - 6 cm/s while drugs and peptides that are absorbed to less than 1% had permeability coefficients of less than or equal to 1 x 10 - 7 cm/s. The results indicate that Caco-2 monolayers can be used as a model for studies on intestinal drug absorption
A new method for the direct measurement of the energy absorption coefficient of gamma rays
International Nuclear Information System (INIS)
Bradley, D.A.; Chong, C.S.; Shukri, A.; Tajuddin, A.A.; Ghose, A.M.
1988-01-01
The most important primary interaction cross section of gamma radiation which is of interest in radiation dosimetry and health physics is the energy absorption coefficient μ en of the medium under study. Direct measurement of μ en is, however, difficult and recourse is t aken to theoretical computations for its estimation. In this study a new, simple and direct method for the determination of μ en is reported. The method is based on paraxial sphere transmission using a proportional-response gamma detector. The bremsstrahlung originating from photoelectrons in the absorbing medium and fluorescence radiations from shielding etc. have been suppressed by using suitable filters. The effects of nonparaxiality of finite sample thickness have been accounted for, using extrapolation procedures. The deviation from nonproportionality and other corrections have been shown to be small. The measured value of μ en for paraffin has been determined as (3.3+-0.2)x10 -3 m 2 /Kg. This compares favourably with the theoretically computed value of 3.35 x 10 -3 m 2 /Kg given by Hubbell et al [pt
Several important optical terms such as "absorbance" and "absorption coefficient" are frequently used ambiguously in the current peer-reviewed literature. Since they are important terms that are required to derive other quantities such as the "apparent quantum yield" of photoprod...
Woestenenk, Janna W; van der Ent, Cornelis K.; Houwen, Roderick H J; van der Ent, CK
Objectives: Pancreatic enzyme replacement therapy (PERT) is the proven therapy to substantially reduce fat malabsorption in patients with cystic fibrosis (CF). Few details of the daily practice regarding PERT and the resulting coefficient of fat absorption (CFA) are known. We therefore recorded the
Ferrero, L; Mocnik, G; Ferrini, B S; Perrone, M G; Sangiorgi, G; Bolzacchini, E
2011-06-15
Vertical profiles of aerosol number-size distribution and black carbon (BC) concentration were measured between ground-level and 500m AGL over Milan. A tethered balloon was fitted with an instrumentation package consisting of the newly-developed micro-Aethalometer (microAeth® Model AE51, Magee Scientific, USA), an optical particle counter, and a portable meteorological station. At the same time, PM(2.5) samples were collected both at ground-level and at a high altitude sampling site, enabling particle chemical composition to be determined. Vertical profiles and PM(2.5) data were collected both within and above the mixing layer. Absorption coefficient (b(abs)) profiles were calculated from the Aethalometer data: in order to do so, an optical enhancement factor (C), accounting for multiple light-scattering within the filter of the new microAeth® Model AE51, was determined for the first time. The value of this parameter C (2.05±0.03 at λ=880nm) was calculated by comparing the Aethalometer attenuation coefficient and aerosol optical properties determined from OPC data along vertical profiles. Mie calculations were applied to the OPC number-size distribution data, and the aerosol refractive index was calculated using the effective medium approximation applied to aerosol chemical composition. The results compare well with AERONET data. The BC and b(abs) profiles showed a sharp decrease at the mixing height (MH), and fairly constant values of b(abs) and BC were found above the MH, representing 17±2% of those values measured within the mixing layer. The BC fraction of aerosol volume was found to be lower above the MH: 48±8% of the corresponding ground-level values. A statistical mean profile was calculated, both for BC and b(abs), to better describe their behaviour; the model enabled us to compute their average behaviour as a function of height, thus laying the foundations for valid parametrizations of vertical profile data which can be useful in both remote sensing
Kelly, B.; Chelsky, A.; Bulygina, E.; Roberts, B. J.
2017-12-01
Remote sensing techniques have become valuable tools to researchers, providing the capability to measure and visualize important parameters without the need for time or resource intensive sampling trips. Relationships between dissolved organic carbon (DOC), colored dissolved organic matter (CDOM) and spectral data have been used to remotely sense DOC concentrations in riverine systems, however, this approach has not been applied to the northern Gulf of Mexico (GoM) and needs to be tested to determine how accurate these relationships are in riverine-dominated shelf systems. In April, July, and October 2017 we sampled surface water from 80+ sites over an area of 100,000 km2 along the Louisiana-Texas shelf in the northern GoM. DOC concentrations were measured on filtered water samples using a Shimadzu TOC-VCSH analyzer using standard techniques. Additionally, DOC concentrations were estimated from CDOM absorption coefficients of filtered water samples on a UV-Vis spectrophotometer using a modification of the methods of Fichot and Benner (2011). These values were regressed against Landsat visible band spectral data for those same locations to establish a relationship between the spectral data, CDOM absorption coefficients. This allowed us to spatially map CDOM absorption coefficients in the Gulf of Mexico using the Landsat spectral data in GIS. We then used a multiple linear regressions model to derive DOC concentrations from the CDOM absorption coefficients and applied those to our map. This study provides an evaluation of the viability of scaling up CDOM absorption coefficient and remote-sensing derived estimates of DOC concentrations to the scale of the LA-TX shelf ecosystem.
Energy Technology Data Exchange (ETDEWEB)
Gurler, O. [Physics Department, Faculty of Arts and Sciences, Uludag University, Gorukle Campus, 16059 Bursa (Turkey)], E-mail: ogurler@uludag.edu.tr; Oz, H. [Physics Department, Faculty of Arts and Sciences, Uludag University, Gorukle Campus, 16059 Bursa (Turkey); Yalcin, S. [Education Faculty, Kastamonu University, 37200 Kastamonu (Turkey); Gundogdu, O. [Department of Physics, University of Surrey, Guildford GU2 7XH (United Kingdom); NCCPM, Medical Physics, Royal Surrey County Hospital, GU2 7XX (United Kingdom)
2009-01-15
The mass energy absorption, the mass energy transfer and mass absorption coefficients have been widely used for problems and applications involving dose calculations. Direct measurements of the coefficients are difficult, and theoretical computations are usually employed. In this paper, analytical equations are presented for determining the mass energy transfer and mass absorption coefficients for gamma rays with an incident energy range between 0.4 and 10 MeV in nitrogen, silicon, carbon, copper and sodium iodide. The mass absorption and mass energy transfer coefficients for gamma rays were calculated, and the results obtained were compared with the values reported in the literature.
International Nuclear Information System (INIS)
Gurler, O.; Oz, H.; Yalcin, S.; Gundogdu, O.
2009-01-01
The mass energy absorption, the mass energy transfer and mass absorption coefficients have been widely used for problems and applications involving dose calculations. Direct measurements of the coefficients are difficult, and theoretical computations are usually employed. In this paper, analytical equations are presented for determining the mass energy transfer and mass absorption coefficients for gamma rays with an incident energy range between 0.4 and 10 MeV in nitrogen, silicon, carbon, copper and sodium iodide. The mass absorption and mass energy transfer coefficients for gamma rays were calculated, and the results obtained were compared with the values reported in the literature
International Nuclear Information System (INIS)
Rao, D.V.; Takeda, T.; Itai, Y.; Akatsuka, T.; Cesareo, R.; Brunetti, A.; Gigante, G.E.
2002-01-01
Compton energy absorption cross sections are calculated using the formulas based on a relativistic impulse approximation to assess the contribution of Doppler broadening and to examine the Compton profile literature and explore what, if any, effect our knowledge of this line broadening has on the Compton component in terms of mass-energy absorption coefficient. Compton energy-absorption cross sections are evaluated for all elements, Z=1-100, and for photon energies 1 keV-100 MeV. Using these cross sections, the Compton component of the mass-energy absorption coefficient is derived in the energy region from 1 keV to 1 MeV for all the elements Z=1-100. The electron momentum prior to the scattering event should cause a Doppler broadening of the Compton line. The momentum resolution function is evaluated in terms of incident and scattered photon energy and scattering angle. The overall momentum resolution of each contribution is estimated for x-ray and γ-ray energies of experimental interest in the angular region 1 deg. -180 deg. . Also estimated is the Compton broadening using nonrelativistic formula in the angular region 1 deg. -180 deg., for 17.44, 22.1, 58.83, and 60 keV photons for a few elements (H, C, N, O, P, S, K, and Ca) of biological importance
Rao, D. V.; Takeda, T.; Itai, Y.; Akatsuka, T.; Cesareo, R.; Brunetti, A.; Gigante, G. E.
2002-09-01
Compton energy absorption cross sections are calculated using the formulas based on a relativistic impulse approximation to assess the contribution of Doppler broadening and to examine the Compton profile literature and explore what, if any, effect our knowledge of this line broadening has on the Compton component in terms of mass-energy absorption coefficient. Compton energy-absorption cross sections are evaluated for all elements, Z=1-100, and for photon energies 1 keV-100 MeV. Using these cross sections, the Compton component of the mass-energy absorption coefficient is derived in the energy region from 1 keV to 1 MeV for all the elements Z=1-100. The electron momentum prior to the scattering event should cause a Doppler broadening of the Compton line. The momentum resolution function is evaluated in terms of incident and scattered photon energy and scattering angle. The overall momentum resolution of each contribution is estimated for x-ray and γ-ray energies of experimental interest in the angular region 1°-180°. Also estimated is the Compton broadening using nonrelativistic formula in the angular region 1°-180°, for 17.44, 22.1, 58.83, and 60 keV photons for a few elements (H, C, N, O, P, S, K, and Ca) of biological importance.
International Nuclear Information System (INIS)
Yu Shao-De; Wu Shi-Bin; Xie Yao-Qin; Wang Hao-Yu; Wei Xin-Hua; Chen Xin; Pan Wan-Long; Hu Jiani
2015-01-01
Similarity coefficient mapping (SCM) aims to improve the morphological evaluation of weighted magnetic resonance imaging However, how to interpret the generated SCM map is still pending. Moreover, is it probable to extract tissue dissimilarity messages based on the theory behind SCM? The primary purpose of this paper is to address these two questions. First, the theory of SCM was interpreted from the perspective of linear fitting. Then, a term was embedded for tissue dissimilarity information. Finally, our method was validated with sixteen human brain image series from multi-echo . Generated maps were investigated from signal-to-noise ratio (SNR) and perceived visual quality, and then interpreted from intra- and inter-tissue intensity. Experimental results show that both perceptibility of anatomical structures and tissue contrast are improved. More importantly, tissue similarity or dissimilarity can be quantified and cross-validated from pixel intensity analysis. This method benefits image enhancement, tissue classification, malformation detection and morphological evaluation. (paper)
International Nuclear Information System (INIS)
Wu Qingjie; Guo Kangxian; Liu Guanghui; Wu Jinghe
2013-01-01
Polaron effects on the linear and the nonlinear optical absorption coefficients and refractive index changes in cylindrical quantum dots with the radial parabolic potential and the z-direction linear potential with applied magnetic field are theoretically investigated. The optical absorption coefficients and refractive index changes are presented by using the compact-density-matrix approach and iterative method. Numerical calculations are presented for GaAs/AlGaAs. It is found that taking into account the electron-LO-phonon interaction, not only are the linear, the nonlinear and the total optical absorption coefficients and refractive index changes enhanced, but also the total optical absorption coefficients are more sensitive to the incident optical intensity. It is also found that no matter whether the electron-LO-phonon interaction is considered or not, the absorption coefficients and refractive index changes above are strongly dependent on the radial frequency, the magnetic field and the linear potential coefficient.
Andreo, Pedro; Burns, David T.; Salvat, Francesc
2012-04-01
A systematic analysis of the available data has been carried out for mass energy-absorption coefficients and their ratios for air, graphite and water for photon energies between 1 keV and 2 MeV, using representative kilovoltage x-ray spectra for mammography and diagnostic radiology below 100 kV, and for 192Ir and 60Co gamma-ray spectra. The aim of this work was to establish ‘an envelope of uncertainty’ based on the spread of the available data. Type A uncertainties were determined from the results of Monte Carlo (MC) calculations with the PENELOPE and EGSnrc systems, yielding mean values for µen/ρ with a given statistical standard uncertainty. Type B estimates were based on two groupings. The first grouping consisted of MC calculations based on a similar implementation but using different data and/or approximations. The second grouping was formed by various datasets, obtained by different authors or methods using the same or different basic data, and with different implementations (analytical, MC-based, or a combination of the two); these datasets were the compilations of NIST, Hubbell, Johns-Cunningham, Attix and Higgins, plus MC calculations with PENELOPE and EGSnrc. The combined standard uncertainty, uc, for the µen/ρ values for the mammography x-ray spectra is 2.5%, decreasing gradually to 1.6% for kilovoltage x-ray spectra up to 100 kV. For 60Co and 192Ir, uc is approximately 0.1%. The Type B uncertainty analysis for the ratios of µen/ρ values includes four methods of analysis and concludes that for the present data the assumption that the data interval represents 95% confidence limits is a good compromise. For the mammography x-ray spectra, the combined standard uncertainties of (µen/ρ)graphite,air and (µen/ρ)graphite,water are 1.5%, and 0.5% for (µen/ρ)water,air, decreasing gradually down to uc = 0.1% for the three µen/ρ ratios for the gamma-ray spectra. The present estimates are shown to coincide well with those of Hubbell (1977 Rad. Res
International Nuclear Information System (INIS)
Williams, P.C.
1985-01-01
The author draws attention to a discussion by Cunningham and Schultz (1984) which states that, 'with the exception of the NACP and AAPM protocols, the selection of stopping power and energy absorption coefficient ratios has been based upon only the stated accelerating potential of the accelerator', and points out that the HPA Revised Code of Practice should be added to these exceptions. In calculating the HPA's new Csub(lambda) values, a similar, but not identical, approach was taken in order to determine the stopping power and absorption coefficient ratios at each radiation quality. It was recognised that the approximation of a spectrum to a monoenergetic spectrum of between 0.4 and 0.45 of the maximum energy, as had been done in calculating the values, given in ICRU Report 14, was incorrect. (U.K.)
International Nuclear Information System (INIS)
Arzate P, N.
1994-01-01
Based on the fundamental theory of cylindrical waveguides and resonant cavities, the main characteristic parameters of the microwave plasma source reported in [1] are calculated. The absorption coefficient of an electromagnetic wave which is excited in H 11 mode in a cylindrical waveguide that contains a cold, inhomogeneous and magnetized plasma column is determined by using the perturbative method describe in [2]. In similar way, due to the presence of the plasma column, the shifts of the resonant frequency and of the inverse of the quality of a cylindrical resonant cavity where a TE 111 mode is oscilating are obtained. Finally, based on the linear theory, an analysis of the penetration of electromagnetic fields in a semi-bounded plasma and a plasma layer is done. The reflexion, transmission and absorption coefficients of H waves for the cases of an isotropic homogeneous and weak inhomogeneous plasma are calculated. (Author)
DEFF Research Database (Denmark)
Jeong, Cheol-Ho
2009-01-01
Most acoustic measurements are based on an assumption of ideal conditions. One such ideal condition is a diffuse and reverberant field. In practice, a perfectly diffuse sound field cannot be achieved in a reverberation chamber. Uneven incident energy density under measurement conditions can cause...... discrepancies between the measured value and the theoretical random incidence absorption coefficient. Therefore the angular distribution of the incident acoustic energy onto an absorber sample should be taken into account. The angular distribution of the incident energy density was simulated using the beam...... tracing method for various room shapes and source positions. The averaged angular distribution is found to be similar to a Gaussian distribution. As a result, an angle-weighted absorption coefficient was proposed by considering the angular energy distribution to improve the agreement between...
International Nuclear Information System (INIS)
Avakian, Ts.M.; Karabekov, I.P.; Martirossian, M.A.
1977-01-01
The results of the measurement of absorption coefficients for some biological objects such as pea (Pissum sativum), wheat (Triticum aestivum), tobacco (Nicotiana-tabacum-α) seeds, as well as the distilled water are presented. The measurement has been carried out on the Erevan Physical Institute Electron Accelerator synchrotron radiation beam. The good agreement of experimental and calculated data for water confirms the accuracy of the results related to other objects
UV absorption coefficients of Y2(1-x-y)Gd2xEu2yO3 phosphors
International Nuclear Information System (INIS)
Ling, M.; Yocom, P.W.; Soules, T.F.
1990-01-01
The ability of a phosphor to absorb 254 nm excitation is important in the development of phosphors for fluorescent lamps. Recently the optical properties of phosphor coating were modeled using ray tracing Monte-Carlo techniques. These calculations provided a relationship between absorptance measured on a semi-infinite plaque at a given wavelength and the product of the absorption coefficient of the phosphor and its particle diameter. The purpose of this work is to provide experimental data for comparison with the calculated data, to demonstrate a technique for obtaining absorption coefficients and to provide UV absorption coefficients obtained in this way for important yttrium oxide europium red-emitting phosphors
Mondal, Rajib; Ko, Sangwon; Norton, Joseph E.; Miyaki, Nobuyuki; Becerril, Hector A.; Verploegen, Eric; Toney, Michael F.; Bré das, Jean-Luc; McGehee, Michael D.; Bao, Zhenan
2009-01-01
Removing the adjacent thiophene groups around the acceptor core in low band gap polymers significantly enhances solar cell efficiency through increasing the optical absorption and raising the ionization potential of the polymer. © 2009 The Royal Society of Chemistry.
International Nuclear Information System (INIS)
Calvin, W.M.
1990-01-01
Reflectance spectra of carbon dioxide frosts were calculated using the optical constants provided by Warren (1986) for the wavelength region 2-6 μm. In comparing these calculated spectra to spectra of frosts observed in the laboratory and on the surface of Mars, problems in the optical constants presented by Warren (1986) became apparent. Absorption coefficients for CO 2 ice have been derived using laboratory reflectance measurements and the Hapke (1981) model for calculating diffuse reflectance. This provides approximate values in regions where no data were previously available and indicates where corrections to the compilation by Warren (1986) are required. Using these coefficients to calculate the reflectance of CO 2 ice at varying grain sizes indicates that a typical Mariner polar cap spectrum is dominated by absorptions due to CO 2 frost or ice at grain sizes that are quite large, probably of the order of millimeters to centimeters. There are indications of contamination of water frost or dust, but confirmation will require more precise absorption coefficients for solid CO 2 than can be obtained from the method used here
International Nuclear Information System (INIS)
Oz, H.; Gurler, O.; Gultekin, A.; Yalcin, S.; Gundogdu, O.
2006-01-01
The absorption coefficients have been widely used for problems and applications involving dose calculations. Direct measurements of the coefficients are difficult, and theoretical computations are usually employed. In this paper, analytical equations are presented for determining the mass energy absorption coefficients for gamma rays with an incident energy range between 0.4 MeV and 10 MeV in silicon, carbon, copper and sodium iodide. The mass energy absorption coefficients for gamma rays were calculated, and the results obtained were compared with the values reported in the literature.
Energy Technology Data Exchange (ETDEWEB)
Oz, H.; Gurler, O.; Gultekin, A. [Uludag University, Bursa (Turkmenistan); Yalcin, S. [Kastamonu University, Kastamonu (Turkmenistan); Gundogdu, O. [University of Surrey, Guildford (United Kingdom)
2006-07-15
The absorption coefficients have been widely used for problems and applications involving dose calculations. Direct measurements of the coefficients are difficult, and theoretical computations are usually employed. In this paper, analytical equations are presented for determining the mass energy absorption coefficients for gamma rays with an incident energy range between 0.4 MeV and 10 MeV in silicon, carbon, copper and sodium iodide. The mass energy absorption coefficients for gamma rays were calculated, and the results obtained were compared with the values reported in the literature.
A simple and rapid procedure for measuring total mercury in fish tissues is evaluated and compared with conventional techniques. Using an automated instrument incorporating combustion, preconcentration by amalgamation with gold, and atomic absorption spectrometry (AAS), mill...
International Nuclear Information System (INIS)
Simeckova, Marie; Jacquemart, David; Rothman, Laurence S.; Gamache, Robert R.; Goldman, Aaron
2006-01-01
This paper describes the calculation of the statistical weights and the Einstein A-coefficients for the 39 molecules and their associated isotopologues/isotopomers currently present in the line-by-line portion of the HITRAN database. Calculation of the Einstein A-coefficients was carried out using the HITRAN line intensities and the necessary statistical weights. The Einstein A-coefficient and the statistical weights of the upper and lower levels of the transition were added in the new format of the line parameters for the most recent edition of the HITRAN database
1987-06-01
polyethylene. The plexiglass is a polymethyl methacrylate and the acrylic is a polymethacrylate . The polyamide(nylon) is made with adipic acid and hexamethylene...are made with acrylic acid . It was not sur- prizing to see both exhibiting similar absorption characteristics atleast 30 times higher than
Radiographic and radioscopic testing of coatings with a high absorption coefficient
International Nuclear Information System (INIS)
Bourdarios, M.; Deleuze, M.; Lepoutre, M.
1983-06-01
Radiographies of a uranium disk obtained with an Ir192 source and a X-ray generator of 420kV are compared. Then a testing installation with a X-ray generator for high absorption material is studied. It comprises a mechanism to put the sample into position and a system for image processing to improve contrast and decrease background noise [fr
Directory of Open Access Journals (Sweden)
Yolanda Villanueva-Palero
2017-06-01
Full Text Available Quantitative photoacoustic imaging in biomedicine relies on accurate measurements of relevant material properties of target absorbers. Here, we present a method for simultaneous measurements of the absorption coefficient and Grüneisen parameter of small volume of liquid scattering and absorbing media using a coupled-integrating sphere system which we refer to as quantitative photoacoustic integrating sphere (QPAIS platform. The derived equations do not require absolute magnitudes of optical energy and pressure values, only calibration of the setup using aqueous ink dilutions is necessary. As a demonstration, measurements with blood samples from various human donors are done at room and body temperatures using an incubator. Measured absorption coefficient values are consistent with known oxygen saturation dependence of blood absorption at 750 nm, whereas measured Grüneisen parameter values indicate variability among five different donors. An increasing Grüneisen parameter value with both hematocrit and temperature is observed. These observations are consistent with those reported in literature.
International Nuclear Information System (INIS)
Pelivanov, Ivan M; Barskaya, M I; Podymova, N B; Khokhlova, Tanya D; Karabutov, Aleksander A
2009-01-01
A new method for measuring the local light absorption coefficient in turbid media, for example, biological tissues, is proposed. The method is based on the fact that the amplitude of the excited opto-acoustic (OA) signal is proportional to the absorbed laser power density (the product of the light absorption coefficient and the laser fluence) at the medium interface. In the first part of the paper, the influence of the laser beam diameter, the light absorption and reduced scattering coefficients on the maximal amplitude of the laser fluence at the laser beam axis in the near-surface layer of the turbid medium is studied by using the Monte-Carlo simulation. The conditions are predicted under which the amplitude of the OA signal detected in a transparent medium in contact with the scattering medium should remain proportional to the light absorption coefficient of the medium under study, when the scattering coefficient in it changes more than twice. The results of the numerical simulation are used for the theoretical substantiation of the OA method being proposed. (measurement of parametrs of laser radiation)
The absorption, tissue distribution and excretion of di-n-octyltin dichloride in rats
Penninks, A.H.; Hilgers, L.; Seinen, W.
In this study the absorption, tissue distribution and excretion of 14C-labeled di-n-octyltin dichloride ([14C]DOTC) in rats were investigated after oral and intravenous (i.v.) administration. Although after i.v. administration with 1.2 mg [14C]DOTC/kg body weight the tissue radioactivity was about
McKee, D.; Röttgers, R.; Neukermans, G.; Calzado, V.S.; Trees, C.; Ampolo-Rella, M.; Neil, C.; Cunningham, A.
2014-01-01
Understanding variability in the chlorophyll-specific absorption of marine phytoplankton, aph*Chl (λ), is essential for primary production modelling, calculation of underwater light field characteristics, and development of algorithms for remote sensing of chlorophyll concentrations. Previous field and laboratory studies have demonstrated significant apparent variability in aph*Chl (λ) for natural samples and algal cultures. However, the potential impact of measurement uncertain...
Energy Technology Data Exchange (ETDEWEB)
Izquierdo, M [Consejo Superior de Investigaciones Cientificas, Madrid (ES). Inst. de Optica; Aroca, S [Escuela Tecnica Superior de Ingenieros Industriales, Valladolid (ES). Catedratico de Ingenieria Termica
1990-04-01
A theoretical study of a lithium bromide absorption heat pump, used as a machine type I and aimed to produce heat at 120{sup 0}C via waste heat sources at 60{sup 0}C, is given. Real performance conditions are stated for each component of the machine. By means of thermodynamic diagrams (p, t, x) and (h, x), the required data are obtained for calculation of the heat recovered in the evaporator Q{sub e}, the heat delivered to the absorber Q{sub a} and to the condenser Q{sub c}, and the heat supplied to the generator Q{sub g}. The heat delivered by the hot solution to the cold solution in the heat recovered Q{sub r}, and the work W{sub p} done by the solution pump are calculated. The probable COP is calculated as close to 1.4 and the working temperature in the generator ranges from 178 to 200{sup 0}C. The heat produced by the heat pump is 22% cheaper than that obtained from a cogeneration system comprising a natural gas internal combustion engine and high temperature heat pump with mechanical compression. Compared with a high temperature heat pump with mechanical compression, the heat produced by the absorption heat pump is 31% cheaper. From (h, x) and (s, x) diagrams, exergy losses for each component can be determined leading to an exergetic efficiency of 75% which provides the quality index of the absorption cycle. (author).
Specific absorption and backscatter coefficient signatures in southeastern Atlantic coastal waters
Bostater, Charles R., Jr.
1998-12-01
Measurements of natural water samples in the field and laboratory of hyperspectral signatures of total absorption and reflectance were obtained using long pathlength absorption systems (50 cm pathlength). Water was sampled in Indian River Lagoon, Banana River and Port Canaveral, Florida. Stations were also occupied in near coastal waters out to the edge of the Gulf Stream in the vicinity of Kennedy Space Center, Florida and estuarine waters along Port Royal Sound and along the Beaufort River tidal area in South Carolina. The measurements were utilized to calculate natural water specific absorption, total backscatter and specific backscatter optical signatures. The resulting optical cross section signatures suggest different models are needed for the different water types and that the common linear model may only appropriate for coastal and oceanic water types. Mean particle size estimates based on the optical cross section, suggest as expected, that particle size of oceanic particles are smaller than more turbid water types. The data discussed and presented are necessary for remote sensing applications of sensors as well as for development and inversion of remote sensing algorithms.
International Nuclear Information System (INIS)
Dryak, P.
1982-01-01
Computation based on the Monte Carlo method was tested for a 4π cylindrical ionization chamber with a detection volume of 7 litres, filled with argon. The sources are placed in the geometrical centre. The correction coefficient for self-absorption was determined as being the ratio of ionization currents induced by a source of finite size and by a massless point source. A flowchart of the program is given. The computations were experimentally tested for cylindrical sources of aqueous 137 Cs and 57 Co solutions. (M.D.)
Directory of Open Access Journals (Sweden)
Mustafa TEMİZ
2008-02-01
Full Text Available In this study, some design parameters such as normalized frequency and especially normalized propagation constant have been obtained, depending on some parameters which are functions of energy eigenvalues of the carriers such as electrons and holes confined in a single step-index waveguide laser (SSIWGL or single stepindex waveguide (SSIWG. Some optical expressions about the optical power and probability quantities for the active region and cladding layers of the SSIWG or SSIWGL have been investigated. Investigations have been undertaken in terms of these parameters and also individually the optical even and odd electric field waves with the lowest-modes were theoretically computed. Especially absorption coefficients and loss coefficients addition to some important quantities of the single step-index waveguide lasers for the even and odd electric field waves are evaluated.
Guan, Fengjiao; Zhang, Guanjun; Liu, Jie; Wang, Shujing; Luo, Xu; Zhu, Feng
2017-10-01
Accurate material parameters are critical to construct the high biofidelity finite element (FE) models. However, it is hard to obtain the brain tissue parameters accurately because of the effects of irregular geometry and uncertain boundary conditions. Considering the complexity of material test and the uncertainty of friction coefficient, a computational inverse method for viscoelastic material parameters identification of brain tissue is presented based on the interval analysis method. Firstly, the intervals are used to quantify the friction coefficient in the boundary condition. And then the inverse problem of material parameters identification under uncertain friction coefficient is transformed into two types of deterministic inverse problem. Finally the intelligent optimization algorithm is used to solve the two types of deterministic inverse problems quickly and accurately, and the range of material parameters can be easily acquired with no need of a variety of samples. The efficiency and convergence of this method are demonstrated by the material parameters identification of thalamus. The proposed method provides a potential effective tool for building high biofidelity human finite element model in the study of traffic accident injury.
International Nuclear Information System (INIS)
Matsusue, Toshio; Bando, Hiroyuki; Fujita, Shoichi; Takayama, Yusuke
2011-01-01
Two-photon absorption (TPA) effect in (001) InP is investigated using fs laser. Its dependences on wavelength and polarization are clarified by single and double beam methods with linearly polarized lights. Characteristic features are revealed and discussed with scaling law, crystal bonding and mutual relation of polarizations for double beams. The results are successfully analyzed on the basis of the third-order susceptibility tensor for comprehensive understanding of TPA effect at any polarization geometry. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
National Oceanic and Atmospheric Administration, Department of Commerce — The Sea surface topography, absorption, scattering, attenuation coefficients and other data in this accession was collected from NOAA-11 satellite in East Coast...
National Oceanic and Atmospheric Administration, Department of Commerce — The Sea surface topography, absorption, scattering, attenuation coefficients and other data in this accession was collected from NOAA-11 AVHRR satellite in East...
Directory of Open Access Journals (Sweden)
Cédric G. Fichot
2016-02-01
Full Text Available Dissolved lignin is a well-established biomarker of terrigenous dissolved organic matter (DOM in the ocean, and a chromophoric component of DOM. Although evidence suggests there is a strong linkage between lignin concentrations and chromophoric DOM (CDOM absorption coefficients in coastal waters, the characteristics of this linkage and the existence of a relationship that is applicable across coastal oceans remain unclear. Here, 421 paired measurements of dissolved lignin concentrations (sum of 9 lignin phenols and CDOM absorption coefficients (ag(λ were used to examine their relationship along the river-ocean continuum (0-37 salinity and across contrasting coastal oceans (sub-tropical, temperate, high-latitude. Overall, lignin concentrations spanned four orders of magnitude and revealed a strong, non-linear relationship with ag(λ. The characteristics of the relationship (shape, wavelength dependency, lignin-composition dependency and evidence from degradation indicators were all consistent with lignin being an important driver of CDOM variability in coastal oceans, and suggested physical mixing and long-term photodegradation were important in shaping the relationship. These observations were used to develop two simple empirical models for estimating lignin concentrations from ag(λ with a +/- 20% error relative to measured values. The models are expected to be applicable in most coastal oceans influenced by terrigenous inputs.
Demkin, Artem S.; Nikitin, Dmitriy G.; Ryabushkin, Oleg A.
2016-04-01
In current work optical properties of LiB3O5 (LBO) crystal with ultraviolet (UV) (λ= 266 nm) induced volume macroscopic defect (track) are investigated using novel piezoelectric resonance laser calorimetry technique. Pulsed laser radiation of 10 W average power at 532 nm wavelength, is consecutively focused into spatial regions with and without optical defect. For these cases exponential fitting of crystal temperature kinetics measured during its irradiation gives different optical absorption coefficients α1 = 8.1 • 10-4 cm-1 (region with defect) and α =3.9ṡ10-4 cm-1 (non-defected region). Optical scattering coefficient is determined as the difference between optical absorption coefficients measured for opaque and transparent lateral facets of the crystal respectively. Measurements reveal that scattering coefficient of LBO in the region with defect is three times higher than the optical absorption coefficient.
Directory of Open Access Journals (Sweden)
S. Yu. Makarov
2015-01-01
Full Text Available The article dwells on a development of new non-invasive measurement methods of optical parameters of biological tissues, which are responsible for the scattering and absorption of monochromatic radiation. It is known from the theory of radiation transfer [1] that for strongly scattering media, to which many biological tissues pertain, such parameters are parameters of diffusion approximation, as well as a scattering coefficient and an anisotropy parameter.Based on statistical modeling the paper examines a spread of non-directional radiation from a Lambert light beam with the natural polarization that illuminates a surface of the biological tissue. Statistical modeling is based on the Monte Carlo method [2]. Thus, to have the correct energy coefficient values of Fresnel reflection and transmission in simulation of such radiation by Monte Carlo method the author uses his finding that is a function of the statistical representation for the incidence of model photons [3]. The paper describes in detail a principle of fixing the power transmitted by the non-directional radiation into biological tissue [3], and the equations of a power balance in this case.Further, the paper describes the diffusion approximation of a radiation transfer theory, often used in simulation of radiation propagation in strongly scattering media and shows its application in case of fixing the power transmitted into the tissue. Thus, to represent an uneven power distribution is used an approximating expression in conditions of fixing a total input power. The paper reveals behavior peculiarities of solution on the surface of the biological tissue inside and outside of the incident beam. It is shown that the solution in the region outside of the incident beam (especially far away from it, essentially, depends neither on the particular power distribution across the surface, being a part of the tissue, nor on the refractive index of the biological tissue. It is determined only by
Apparent diffusion coefficient of the renal tissue. The effect of diuretic
Energy Technology Data Exchange (ETDEWEB)
Yamamoto, Jin; Munechika, Hirotsugu [Showa Univ., Tokyo (Japan). School of Medicine
1998-12-01
Apparent diffusion coefficient (ADC) of the renal tissue was studied at diffusion-weighted images of the kidney which were obtained from spin-echo type sequence before and after furosemide (100 mg) injection in twelve healthy volunteers. ADC (mm{sup 2}/sec) of the renal cortex and medulla before furosemide injection was 2.08{+-}0.52 and 1.96{+-}0.52, respectively. No appreciable ADC difference was seen between the cortex and the medulla of the kidney. After furosemide injection, ADC of the renal cortex and medulla became 2.09{+-}0.42 and 1.78{+-}0.38, respectively. It was found that furosemide produced no significant effect on ADC of the renal tissue. (author)
Measurement of X-ray attenuation coefficients around K-absorption edges using Fe Kα X-rays
International Nuclear Information System (INIS)
Kerur, B.R.; Thontadarya, S.R.; Hanumaiah, B.
1993-01-01
The x-ray mass attenuation coefficients were measured around the K-absorption edges of elements in the range 16 ≤ Z ≤ 30 using Fe Kα x-rays of energy 6.400 keV, which is the weighted average energy of Kα 1 and Kα 2 x-ray components from the 57 Co radioactive source. Kβ x-rays were almost eliminated by the differential absorption technique. The small difference in energy between Kα 1 and Kα 2 , 13 eV, was shown to be inconsequential by comparing the measured and theoretical values of μ/ρ for standard materials such as Al, Cu, Mo and Ta. The effect of fine structure of the K-absorption edge on μ/ρ was elucidated by using the compounds of elements in the range 16 ≤ X ≤ 30, containing one element with its K-absorption edge energy (E k ) close to the incident photon energy (E x ). The results clearly indicate the validity of the theoretical mixture rule for all those compounds whose K edge is far away from the incident energy but show deviations of as much as 10% for the manganese compound whose K edge is 140 eV above E x and about 12% for the chromium compound whose K edge is 410 eV below E x . These deviations are attributed to the possible influence of resonance Raman scattering when the incident photon energy E x is less than the edge and to the influence of EXAFS when E x is more than the edge energy. (Author)
Energy-Looping Nanoparticles: Harnessing Excited-State Absorption for Deep-Tissue Imaging.
Levy, Elizabeth S; Tajon, Cheryl A; Bischof, Thomas S; Iafrati, Jillian; Fernandez-Bravo, Angel; Garfield, David J; Chamanzar, Maysamreza; Maharbiz, Michel M; Sohal, Vikaas S; Schuck, P James; Cohen, Bruce E; Chan, Emory M
2016-09-27
Near infrared (NIR) microscopy enables noninvasive imaging in tissue, particularly in the NIR-II spectral range (1000-1400 nm) where attenuation due to tissue scattering and absorption is minimized. Lanthanide-doped upconverting nanocrystals are promising deep-tissue imaging probes due to their photostable emission in the visible and NIR, but these materials are not efficiently excited at NIR-II wavelengths due to the dearth of lanthanide ground-state absorption transitions in this window. Here, we develop a class of lanthanide-doped imaging probes that harness an energy-looping mechanism that facilitates excitation at NIR-II wavelengths, such as 1064 nm, that are resonant with excited-state absorption transitions but not ground-state absorption. Using computational methods and combinatorial screening, we have identified Tm(3+)-doped NaYF4 nanoparticles as efficient looping systems that emit at 800 nm under continuous-wave excitation at 1064 nm. Using this benign excitation with standard confocal microscopy, energy-looping nanoparticles (ELNPs) are imaged in cultured mammalian cells and through brain tissue without autofluorescence. The 1 mm imaging depths and 2 μm feature sizes are comparable to those demonstrated by state-of-the-art multiphoton techniques, illustrating that ELNPs are a promising class of NIR probes for high-fidelity visualization in cells and tissue.
Measurement of the first Townsend ionization coefficient in a methane-based tissue-equivalent gas
Energy Technology Data Exchange (ETDEWEB)
Petri, A.R. [Instituto de Pesquisas Energéticas e Nucleares, Cidade Universitária, 05508-000 São Paulo (Brazil); Gonçalves, J.A.C. [Instituto de Pesquisas Energéticas e Nucleares, Cidade Universitária, 05508-000 São Paulo (Brazil); Departamento de Física, Pontifícia Universidade Católica de São Paulo, 01303-050 São Paulo (Brazil); Mangiarotti, A. [Instituto de Física - Universidade de São Paulo, Cidade Universitária, 05508-080 São Paulo (Brazil); Botelho, S. [Instituto de Pesquisas Energéticas e Nucleares, Cidade Universitária, 05508-000 São Paulo (Brazil); Bueno, C.C., E-mail: ccbueno@ipen.br [Instituto de Pesquisas Energéticas e Nucleares, Cidade Universitária, 05508-000 São Paulo (Brazil)
2017-03-21
Tissue-equivalent gases (TEGs), often made of a hydrocarbon, nitrogen, and carbon dioxide, have been employed in microdosimetry for decades. However, data on the first Townsend ionization coefficient (α) in such mixtures are scarce, regardless of the chosen hydrocarbon. In this context, measurements of α in a methane-based tissue-equivalent gas (CH{sub 4} – 64.4%, CO{sub 2} – 32.4%, and N{sub 2} – 3.2%) were performed in a uniform field configuration for density-normalized electric fields (E/N) up to 290 Td. The setup adopted in our previous works was improved for operating at low pressures. The modifications introduced in the apparatus and the experimental technique were validated by comparing our results of the first Townsend ionization coefficient in nitrogen, carbon dioxide, and methane with those from the literature and Magboltz simulations. The behavior of α in the methane-based TEG was consistent with that observed for pure methane. All the experimental results are included in tabular form in the .
Directory of Open Access Journals (Sweden)
Ze-Hong Fu
2017-08-01
Full Text Available Objective: To study the correlation of MRI apparent diffusion coefficient (ADC value of invasive breast cancer with tumor tissue growth and angiogenesis. Methods: Patients with breast mass who were treated in Wuhan No. 6 Hospital between March 2014 and May 2017 were selected as the research subjects and divided into group A with invasive ductal carcinoma, group B with intraductal carcinoma and group C with benign lesion according to the biopsy results, magnetic resonance diffusion-weighted imaging was conducted to determine ADC values, and biopsy tissue was taken to determine the expression of proliferation genes and angiogenesis genes. Results: USP39, CyclinD1, VEGF, bFGF, Angplt-2, Angplt-3 and Angplt-4 protein expression levels in lesions of group A and group B were significantly higher than those of group C while ADC value as well as ALEX1 and Bax protein expression levels were significantly lower than those of group C; USP39, CyclinD1, VEGF, bFGF, Angplt-2, Angplt-3 and Angplt-4 protein expression levels in lesions of group A were significantly higher than those of group B while ADC value as well as ALEX1 and Bax protein expression levels was significantly lower than those of group B; USP39, CyclinD1, VEGF, bFGF, Angplt-2, Angplt-3 and Angplt-4 protein expression levels in invasive breast cancer tissue with high ADC value were significantly lower than those in invasive breast cancer tissue with low ADC value while ALEX1 and Bax protein expression levels were significantly higher than those in invasive breast cancer tissue with low ADC value. Conclusion: The decrease of ADC value of invasive breast cancer is closely related to cancer cell proliferation and angiogenesis.
Effects of dehydration on corneal tissue absorption of topical azithromycin in rabbits.
Tabbara, Khalid F; Kotb, Amgad A; Hammouda, Ehab F; Elkum, Naser
2005-10-01
To assess the corneal tissue absorption of azithromycin in desiccated and normal eyes of rabbits. A total of 25 New Zealand Albino rabbits weighing 2-3 kg each were included. One eye of each rabbit was desiccated. The other eye was left as control. Azithromycin 1.5% topical eyedrops were instilled in both eyes. Five rabbits were sacrificed at each of the following time points: 30 min, 3 hr, 6 hr, and 12 hr. Corneal tissues specimens were subjected to high-performance liquid chromatography mass spectrometry. A paired t test was used to evaluate the statistical difference in corneal tissue absorptions of azithromycin at each time point. The mean corneal tissue levels of azithromycin in dry eyes were 66.3 microg/ml, 92.6 microg/ml, 117.5 microg/ml, and 179.9 microg/ml, and the mean corneal tissue levels of azithromycin in normal eyes were 42.0 microg/ml, 43.4 microg/ml, 43.3 microg/ml, and 80.0 microg/ml at 30 min, 3 hr, 6 hr, and 12 hr respectively. Both groups showed increase in corneal tissue absorption overtime (p < 0.0001). Significantly higher levels of azithromycin were noted in dry eyes at each time point except at the 30-min time point. This study demonstrated that corneas exposed to desiccation showed statistically significant increase in azithromycin level compared to normal eyes.
Compositional dependence of absorption coefficient and band-gap for Nb2O5-SiO2 mixture thin films
International Nuclear Information System (INIS)
Sancho-Parramon, Jordi; Janicki, Vesna; Zorc, Hrvoje
2008-01-01
The absorption coefficient of composite films consisting of niobia (Nb 2 O 5 ) and silica (SiO 2 ) mixtures is studied for photon energies around the band gap. The films were deposited by co-evaporation and their composition was varied by changing the ratio of deposition rates of the two materials. Both, as-deposited and thermally annealed films were characterized by different techniques: the absorption coefficient was determined by spectrophotometric measurements and the structural properties were investigated using infrared spectroscopy, transmission electron microscopy and X-ray diffraction. The correlation between the variations of absorption properties and film composition and structure is established. The absorption coefficients determined experimentally are compared with the results derived from effective medium theories in order to evaluate the suitability of these theories for the studied composites
Cuppo, F L S; Gómez, S L; Figueiredo Neto, A M
2004-04-01
In this paper is reported a systematic experimental study of the linear-optical-absorption coefficient of ferrofluid-doped isotropic lyotropic mixtures as a function of the magnetic-grains concentration. The linear optical absorption of ferrolyomesophases increases in a nonlinear manner with the concentration of magnetic grains, deviating from the usual Beer-Lambert law. This behavior is associated to the presence of correlated micelles in the mixture which favors the formation of small-scale aggregates of magnetic grains (dimers), which have a higher absorption coefficient with respect to that of isolated grains. We propose that the indirect heating of the micelles via the ferrofluid grains (hyperthermia) could account for this nonlinear increase of the linear-optical-absorption coefficient as a function of the grains concentration.
International Nuclear Information System (INIS)
Rajan, N.; Nigam, A.K.
1984-01-01
The total electronic absorption coefficient for 14.4 keV gamma photons in aluminium, has been measured experimentally, for the first time, using the Moessbauer effect as a monochromator. This data is important for the determination of background in Moessbauer recoilless fraction measurements especially if the energy of X-rays of the source host lattice lie near the 14.4 keV photon energy (e.g. in Rh and Pd) in which case electronic absorption coefficients should be known precisely. The coefficient obtained by interpolation from available values at other energies differ from our experimental value by as much as 20%. It is shown that this can lead to errors, in recoilless fraction values, which are far from negligible. The above absorption coefficient for aluminium was measured to be 11+-1 cm 2 /g. (orig.)
International Nuclear Information System (INIS)
Falcao-Filho, E.L.; Araujo, Cid B. de; Bosco, C.A.C.; Maciel, G.S.; Acioli, L.H.; Nalin, M.; Messaddeq, Y.
2005-01-01
Antimony glasses based on the composition Sb 2 O 3 -SbPO 4 were prepared and characterized. The samples present high refractive index, good transmission from 380 to 2000 nm, and high thermal stability. The nonlinear refractive index, n 2 , of the samples was studied using the optical Kerr shutter technique at 800 nm. The third-order correlation signals between pump and probe pulses indicate ultrafast response ( 2 was observed by adding lead oxide to the Sb 2 O 3 -SbPO 4 composition. Large values of n 2 ≅10 -14 cm 2 /W and negligible two-photon absorption coefficients (smaller than 0.01 cm/GW) were determined for all samples. The glass compositions studied present appropriate figure-of-merit for all-optical switching applications
DEFF Research Database (Denmark)
Jeong, Cheol-Ho
2011-01-01
resistivity and the absorber thickness on the difference between the two surface reaction models are examined and discussed. For a porous absorber backed by a rigid surface, the assumption of local reaction always underestimates the random incidence absorption coefficient and the local reaction models give...... incidence acoustical characteristics of typical building elements made of porous materials assuming extended and local reaction. For each surface reaction, five well-established wave propagation models, the Delany-Bazley, Miki, Beranek, Allard-Champoux, and Biot model, are employed. Effects of the flow...... errors of less than 10% if the thickness exceeds 120 mm for a flow resistivity of 5000 Nm-4s. As the flow resistivity doubles, a decrease in the required thickness by 25 mm is observed to achieve the same amount of error. For an absorber backed by an air gap, the thickness ratio between the material...
Westerhout, J.; Steeg, E. van de; Grossouw, D.; Zeijdner, E.E.; Krul, C.A.M.; Verwei, M.; Wortelboer, H.M.
2014-01-01
A reliable prediction of the oral bioavailability in humans is crucial and of high interest for pharmaceutical and food industry. The predictive value of currently used in silico methods, in vitro cell lines, ex vivo intestinal tissue and/or in vivo animal studies for human intestinal absorption,
Wei, Jianwei; Lee, Zhongping; Ondrusek, Michael; Mannino, Antonio; Tzortziou, Maria; Armstrong, Roy
2016-03-01
The spectral slope of the absorption coefficient of colored dissolved and detrital material (CDM), S cdm (units: nm -1 ), is an important optical parameter for characterizing the absorption spectral shape of CDM. Although highly variable in natural waters, in most remote sensing algorithms, this slope is either kept as a constant or empirically modeled with multiband ocean color in the visible domain. In this study, we explore the potential of semianalytically retrieving S cdm with added ocean color information in the ultraviolet (UV) range between 360 and 400 nm. Unique features of hyperspectral remote sensing reflectance in the UV-visible wavelengths (360-500 nm) have been observed in various waters across a range of coastal and open ocean environments. Our data and analyses indicate that ocean color in the UV domain is particularly sensitive to the variation of the CDM spectral slope. Here, we used a synthesized data set to show that adding UV wavelengths to the ocean color measurements will improve the retrieval of S cdm from remote sensing reflectance considerably, while the spectral band settings of past and current satellite ocean color sensors cannot fully account for the spectral variation of remote sensing reflectance. Results of this effort support the concept to include UV wavelengths in the next generation of satellite ocean color sensors.
Gatti, Giorgio; Olivas Olivera, Diana F; Sacchetto, Vittoria; Cossi, Maurizio; Braschi, Ilaria; Marchese, Leonardo; Bisio, Chiara
2017-09-06
Determination of the molar absorption coefficients of the CH 3 bending mode at ν˜ =1380 cm -1 (ϵ 1380 ) of n-hexane adsorbed from the gas phase on two different dealuminated zeolites is derived by a combination of IR spectroscopy and microgravimetric analysis. High-silica zeolite Y (HSZ-Y) and zeolite ZSM-5 (with SiO 2 /Al 2 O 3 ratios of 200 and 280, respectively) with different textural and surface features are selected to evaluate the effect of the pore structure and architecture on the value of ϵ 1380 of the adsorbed n-hexane. Experimental data indicate that the molecule experiences a different adsorption environment inside zeolites; thus resulting in a significant change of the dipole moment and very different ϵ 1380 values: (0.278±0.018) cm μmol -1 for HSZ-Y and (0.491±0.032) cm μmol -1 for ZSM-5. Experimental data are also supported by computational modeling, which confirms the effect of different matrices on the IR absorption intensity. This study reveals that the use of probe molecules for quantitative measurements of surface sites has to be judiciously adopted, especially if adsorption occurs in the restricted spaces of microporous materials. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Moiseeva, N.; Churilova, T.; Efimova, T.; Krivenko, O.; Latushkin, A.
2017-11-01
Variability of the bio-optical properties of the Crimean coastal waters in June 2016 has been analyzed. The type of vertical distribution chlorophyll a concentration and phytoplankton light absorption coefficients and spectra shape differed between shallow and deeper water. In the deeper water seasonal stratification divided euphotic zone into layers with different environmental conditions. In the deeper part of the euphotic zone (below the thermocline) phytoplankton absorption spectra had local maximum at 550 nm, which was likely to be associated with high abundance of cyanobacteria (Synechococcus sps.) in the phytoplankton community. The concentration of chlorophyll a specific light absorption coefficient of phytoplankton decreased with depth (especially pronounced in the blue domain of the spectrum). In the shallow water the vertical distributions of all absorption properties were relatively homogeneous due to vertical water mixing. In the shallow water non-algal particles light absorption coefficient and its contribution to total particulate absorption were higher than those in the deeper water. The non-algal particles (NAP) and colored dissolved organic matter (CDOM) light absorption spectra were well described by an exponential function with a slope averaging 0.010 nm-1 (SD = 0.001 nm-1) and 0.022 nm-1 (SD = 0.0060 nm-1), correspondingly. The CDOM absorption at 440 nm and slope coefficient varied significantly across the investigated area, which was possibly associated with the terrestrial influences. The assessment of the contribution of phytoplankton, NAP and CDOM to total light absorption showed that CDOM dominated in the absorption at 440 nm.
Zhang, Xi; Zheng, Shaodi; Zheng, Xiaofang; Liu, Zhengying; Yang, Wei; Yang, Mingbo
2016-03-21
In this article, the positive temperature coefficient (PTC) effect was studied for high-density polyethylene (HDPE)/carbon fiber (CF) composites. All of the samples showed a significant PTC effect during the heating processes without a negative temperature coefficient (NTC) effect, even at a temperature much higher than the melting point of the polymer matrix. An ever-increasing PTC intensity with increasing thermal cycles was observed in our study that had never been reported in previous research. The absence of a NTC effect resulted from the increased binding force between the matrix and fillers that contributed to the very special structure of CF surface. We incorporated thermal expansion theory and quantum tunneling effects to explain PTC effect. From the SEM micrographs for the HDPE/CF composites before and after the different thermal cycles, we found that the surface of CF was covered with a layer of polymer which resulted in a change in the gap length between CF and HDPE and its distribution. We believed that the gap change induced by polymer absorption on the fiber surface had a great effect on the PTC effect.
Shrestha, Pranav; Stoeber, Boris
2017-11-01
Hollow microneedles provide a promising alternative to conventional drug delivery techniques due to improved patient compliance and the dose sparing effect. The dynamics of fluid injected through hollow microneedles into skin, which is a heterogeneous and deformable porous medium, have not been investigated extensively in the past. We have introduced the use of Optical Coherence Tomography (OCT) for real-time visualization of fluid injections into excised porcine tissue. The results from ex-vivo experiments, including cross-sectional tissue images from OCT and pressure/flow-rate measurements, show a transient mode of high flow-rate into the tissue followed by a lower steady-state infusion rate. The injected fluid expands the underlying tissue and causes the external free surface of the skin to rise, forming a characteristic intradermal wheal. We have used OCT to visualize the evolution of tissue and free surface deformation, and advancement of the boundary between regions of expanding and stationary tissue. We will show the effect of different injection parameters such as fluid pressure, viscosity and microneedle retraction on the injected volume. This work has been supported through funding from the Collaborative Health Research Program by the Natural Science and Engineering Research Council of Canada and the Canadian Health Research Institute, and through the Canada Research Chairs program.
Energy Technology Data Exchange (ETDEWEB)
Pawlak, M., E-mail: mpawlak@fizyka.umk.pl [Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziądzka 5/7, Toruń (Poland); Maliński, M. [Department of Electronics and Computer Science, Koszalin University of Technology, 2 Śniadeckich St., Koszalin 75-453 (Poland)
2015-01-10
Highlights: • The new method of determination of the effective infrared absorption coefficient is presented. • The method can be used for transparent samples for the excitation radiation. • The effect of aluminum foil on the PTR signal in a transmission configuration is discussed. - Abstract: In this paper we propose a new procedure of simultaneous estimation of the effective infrared optical absorption coefficient and the thermal diffusivity of solid state samples using the photothermal infrared radiometry method in the transmission configuration. The proposed procedure relies on the analysis of the frequency dependent signal obtained from the samples covered with thin aluminum foil. This method can be applied for both optically opaque and transparent samples. The proposed method is illustrated with the results of the thermal diffusivity and the effective IR absorption coefficient obtained for several Cd{sub 1−x}Mg{sub x}Se crystals.
International Nuclear Information System (INIS)
Mughnetsyan, V.N.; Manaselyan, A.Kh.; Barseghyan, M.G.; Kirakosyan, A.A.
2013-01-01
In this paper the simultaneous effect of hydrostatic pressure and Rashba spin–orbit interaction on intraband linear and nonlinear light absorption has been investigated in cylindrical quantum ring. The one electron energy spectrum has been found using the effective mass approximation and diagonalization procedure. We have found that the Rashba interaction can lead both to the blue- or to the red-shift of the absorption spectrum depending on the transitions character, while the only red-shift is observed due to the hydrostatic pressure. - Highlights: ► The effects of hydrostatic pressure and spin–orbit coupling are investigated for quantum ring. ► The non-linear absorption coefficient is calculated. ► The hydrostatic pressure leads to the decrease in the absorption coefficient. ► Spin–orbit coupling weakens some transitions and strengthens others.
DEFF Research Database (Denmark)
Jelnes, Rolf; Astrup, A; Bülow, J
1985-01-01
the partition coefficient found by the double isotope technique, significantly lower values are obtained than if the in vitro determined coefficient is used. This difference is explained mainly by local dilution when injecting xenon subcutaneously. In short-term studies, utilization of the double isotope...... technique reduces the coefficient of variation on average flow determinations, thus an improvement in accuracy of local blood flow estimation can be obtained compared to the method in which an average partition coefficient is used. For long-term studies a partition coefficient of 7.5 ml g-1 seems valid.......Local subcutaneous 133xenon (133Xe) elimination was registered in the human forefoot in 34 patients. The tissue/blood partition coefficient for Xe was estimated individually by simultaneous registration of 133Xe and [131I]antipyrine ([131I]AP) washout from the same local depot. When measured...
Alcantara, E.; Bernardo, N.
2016-12-01
Colored dissolved organic matter (CDOM) is the most abundant dissolved organic matter (DOM) in many natural waters and can affect the water quality, such as the light penetration and the thermal properties of water system. So the objective of this letter was to estimate the colored dissolved organic matter (CDOM) absorption coefficient at 440 nm, aCDOM(440), in Barra Bonita Reservoir (São Paulo State, Brazil) using OLI/Landsat-8 images. For this two field campaigns were conducted in May and October 2014. During the field campaigns remote sensing reflectance (Rrs) were measured using a TriOS hyperspectral radiometer. Water samples were collected and analyzed to obtain the aCDOM(440). To predict the aCDOM(440) from Rrs at two key wavelengths (650 and 480 nm) were regressed against laboratory derived aCDOM(440) values. The validation using in situ data of aCDOM(440) algorithm indicated a goodness of fit, R2 = 0.70, with a root-mean-square error (RMSE) of 10.65%. The developed algorithm was applied to the OLI/Lansat-8 images. Distribution maps were created with OLI/Landsat-8 images based on the adjusted algorithm.
International Nuclear Information System (INIS)
Fookes, R.A.; Gravitis, V.L.; Watt, J.S.
1977-01-01
A method for determining the ash content of coal is proposed. It involves measurements proportional to mass absorption coefficients of coal at two X-ray energies. These measurements can be made using X-ray transmission or scatter techniques. Calculations based on transmission of narrow beams of X-rays have shown that ash can be determined to about 1wt%(1 sigma) in coal of widely varying ash content and composition. Experimentally, ash content was determined to 0.67wt% by transmission techniques and 1.0wt% by backscatter techniques in coal samples from the Bulli seam, NSW, Australia, having ash in the range 11-34wt%. For samples with a much wider range of coal composition (7-53wt% ash and 0-25wt% iron in the ash), ash content was determined by backscatter measurements to 1.62wt%. The method produced ash determinations at least as accurate as those produced by the established technique which compensates for variation in iron content of the ash by X-ray fluorescence analysis for iron. Compared with the established technique, it has the advantage of averaging analysis over much larger volumes of coal, but the disadvantage that much more precise measurements of X-ray intensities are required. (author)
Measurements of the static friction coefficient between bone and muscle tissues.
Shacham, Sharon; Castel, David; Gefen, Amit
2010-08-01
This study aimed at measuring the static coefficient of friction (mu) between bone and skeletal muscle tissues in order to support finite element (FE) modeling in orthopaedic and rehabilitation research, where such contact conditions need to be defined. A custom-made friction meter (FM) that employs the load cell and motion-controlled loading arm of a materials testing machine was designed for this study. The FM was used to measure mu between fresh ulna bones and extensor muscles surrounding the ulna, which were harvested from five young adult pigs. Mean bone-muscle mu were between 0.36 and 0.29, decreased with the increase in loads applied on the bone (p<0.05) and plateaued at a mean approximately 0.3 for loads exceeding 4 N. Hence, for FE modeling of bone-muscle contacts through which loads with magnitudes of kgs to 10s-of-kgs are transferred, assuming mu of approximately 0.3 appears to be appropriate.
Energy Technology Data Exchange (ETDEWEB)
Zamorano, M; Torres-Silva, H [Departamento de Electronica, Universidad de Tarapaca, 18 de Septiembre 2222, Arica (Chile)
2006-04-07
A new electrodynamics model formed by chiral bioplasma, which represents the human head inner structure and makes it possible to analyse its behaviour when it is irradiated by a microwave electromagnetic field from cellular phones, is presented. The finite-difference time-domain (FDTD) numeric technique is used, which allows simulation of the electromagnetic fields, deduced with Maxwell's equations, and allows us to simulate the specific absorption rate (SAR). The results show the SAR behaviour as a function of the input power and the chirality factor. In considering the chiral brain tissue in the proposed human head model, the two more important conclusions of our work are the following: (a) the absorption of the electromagnetic fields from cellular phones is stronger, so the SAR coefficient is higher than that using the classical model, when values of the chiral factor are of order of 1; (b) 'inverse skin effect' shows up at 1800 MHz, with respect to a 900 MHz source.
Oral absorption and tissue distribution of a new squalenoyl anticancer nanomedicine
Energy Technology Data Exchange (ETDEWEB)
Harivardhan Reddy, L.; Ferreira, Humberto; Dubernet, Catherine [Univ. Paris-Sud XI, Faculte de Pharmacie, UMR CNRS 8612, IFR 141 (France); Mouelhi, Sinda Lepetre; Desmaele, Didier [Universite Paris XI, Faculte de Pharmacie, UMR CNRS 8076 Biocis (France); Rousseau, Bernard [CEA, Bio Organic Chemistry and Labeled Compounds Division (France); Couvreur, Patrick [Univ. Paris-Sud XI, Faculte de Pharmacie, UMR CNRS 8612, IFR 141 (France)], E-mail: patrick.couvreur@u-psud.fr
2008-05-15
Recently, we had discovered that the linkage of nucleoside analogues to squalene, a precursor in the sterol biosynthesis, led to amphiphilic molecules, which self-organized in water as nanoassemblies of 100-300 nm in diameter, irrespective of the nucleoside analogue used. Thus, it was observed that the 4-(N)-trisnorsqualenoylgemcitabine (SQdFdC), the squalenoyl prodrug of the anticancer nucleoside analogue gemcitabine, was impressively more active than its parent compound gemcitabine, both in vitro and in vivo on experimental leukaemia. Since squalene, which is a natural constituent of shark liver and olive oil, is known to be absorbed orally, we investigated in this short note the absorption and tissue distribution of {sup 3}H-radiolabelled SQdFdC nanoassemblies comparatively to {sup 3}H-gemcitabine after oral administration to mice. Whereas gemcitabine was found to be rapidly absorbed (t{sub max} = 1 h), this compound underwent a rapid clearance from the plasma. Conversely, the SQdFdC nanoassemblies displayed slower absorption followed by the progressive tissue accumulation, and they exhibited a lower clearance rate. The accumulation of the SQdFdC nanoassemblies in tissues such as pancreas, thymus, lung, liver and spleen (except at 1 h post-administration) was similar to that of the gemcitabine, yet exhibited significantly greater penetration and retention into the stomach and intestinal tissues comparatively to gemcitabine. Thus, the SQdFdC nanoassemblies could be of potential interest in the treatment of gastrointestinal tumours by oral route.
International Nuclear Information System (INIS)
Joksimovicj, V.
1976-01-01
The absorption coefficients of X-rays from 100 to 400 keV through barium plaster of equivalent atomic number of 26 have been determined experimentally and theoretically. Calculated values are compared with experimental data. Matrix components of barium plaster were determined chemically and by X-ray fluorescence
Comparison of absorption spectra of adenocarcinoma and squamous cell carcinoma cervical tissue
Peresunko, O. P.; Zelinska, N. V.; Prydij, O. G.; Zymnyakov, D. A.; Ushakova, O. V.
2013-12-01
We studied a methods of assessment of a connective tissue of cervix in terms of specific volume of fibrous component and an optical density of staining of connective tissue fibers in the stroma of squamous cancer and cervix adenocarcinoma. An absorption spectra of blood plasma of the patients suffering from squamous cancer and cervix adenocarcinoma both before the surgery and in postsurgical periods were obtained. Linear dichroism measurements transmittance in polarized light at different orientations of the polarization plane relative to the direction of the dominant orientation in the structure of the sample of biotissues of stroma of squamous cancer and cervix adenocarcinoma were carried. Results of the investigation of the tumor tissues showed that the magnitude of the linear dichroism Δ is insignificant in the researched spectral range λ=280-840 nm and specific regularities in its change observed short-wave ranges.
Energy Technology Data Exchange (ETDEWEB)
Kurudirek, Murat, E-mail: mkurudirek@gmail.co [Faculty of Science, Department of Physics, Ataturk University, 25240 Erzurum (Turkey); Dogan, Bekir [Faculty of Science, Department of Physics, Ataturk University, 25240 Erzurum (Turkey); Ingec, Metin [Faculty of Medicine, Department of Obstetrics and Gynecology, Ataturk University, 25240 Erzurum (Turkey); Ekinci, Neslihan; Ozdemir, Yueksel [Faculty of Science, Department of Physics, Ataturk University, 25240 Erzurum (Turkey)
2011-02-15
Human tissues with endometriosis have been analyzed in terms of energy absorption (EABF) and exposure (EBF) buildup factors using the five-parameter geometric progression (G-P) fitting formula in the energy region 0.015-15 MeV up to a penetration depth of 40 mfp (mean free path). Chemical compositions of the tissue samples were determined using a wavelength dispersive X-ray fluorescence spectrometer (WDXRFS). Possible conclusions were drawn due to significant variations in EABF and EBF for the selected tissues when photon energy, penetration depth and chemical composition changed. Buildup factors so obtained may be of use when the method of choice for treatment of endometriosis is radiotherapy.
DEFF Research Database (Denmark)
Manohara, S. R.; Hanagodimath, S. M.; Gerward, Leif
2011-01-01
Energy absorption geometric progression (GP) fitting parameters and the corresponding buildup factors have been computed for human organs and tissues, such as adipose tissue, blood (whole), cortical bone, brain (grey/white matter), breast tissue, eye lens, lung tissue, skeletal muscle, ovary......, testis, soft tissue, and soft tissue (4-component), for the photon energy range 0.015-15 MeV and for penetration depths up to 40 mfp (mean free path). The chemical composition of human organs and tissues is seen to influence the energy absorption buildup factors. It is also found that the buildup factor...... of human organs and tissues changes significantly with the change of incident photon energy and effective atomic number, Zeff. These changes are due to the dominance of different photon interaction processes in different energy regions and different chemical compositions of human organs and tissues...
Grad, S; Loparic, M; Peter, R; Stolz, M; Aebi, U; Alini, M
2012-04-01
Functional cartilage tissue engineering aims to generate grafts with a functional surface, similar to that of authentic cartilage. Bioreactors that stimulate cell-scaffold constructs by simulating natural joint movements hold great potential to generate cartilage with adequate surface properties. In this study two methods based on atomic force microscopy (AFM) were applied to obtain information about the quality of engineered graft surfaces. For better understanding of the molecule-function relationships, AFM was complemented with immunohistochemistry. Bovine chondrocytes were seeded into polyurethane scaffolds and subjected to dynamic compression, applied by a ceramic ball, for 1h daily [loading group 1 (LG1)]. In loading group 2 (LG2), the ball additionally oscillated over the scaffold, generating sliding surface motion. After 3 weeks, the surfaces of the engineered constructs were analyzed by friction force and indentation-type AFM (IT-AFM). Results were complemented and compared to immunohistochemical analyses. The loading type significantly influenced the mechanical and histological outcomes. Constructs of LG2 exhibited lowest friction coefficient and highest micro- and nanostiffness. Collagen type II and aggrecan staining were readily observed in all constructs and appeared to reach deeper areas in loaded (LG1, LG2) compared to unloaded scaffolds. Lubricin was specifically detected at the top surface of LG2. This study proposes a quantitative AFM-based functional analysis at the micrometer- and nanometer scale to evaluate the quality of cartilage surfaces. Mechanical testing (load-bearing) combined with friction analysis (gliding) can provide important information. Notably, sliding-type biomechanical stimuli may favor (re-)generation and maintenance of functional articular surfaces and support the development of mechanically competent engineered cartilage. Copyright Â© 2012 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights
Abutalib, M M; Yahia, I S
2017-09-01
In the current work, the authors report the microwave-assisted synthesis Molybdenum-doped (from 0.05 to 5wt%) hydroxyapatite (HAp) for the first time. The morphology of Mo-doped HAp is nanorods of diameter in the range of 25-70nm and length in the range of 25nm to 200nm. The good crystalline nature was confirmed from X-ray diffraction patterns and also lattice parameters, grain size, strain and dislocation density were determined. The crystallite size was found to be in the range 16 to 30nm and crystallinity was found to be enhanced from 0.5 to 0.7 with doping. The field emission SEM micrographs show that the morphology of the synthesized nanostructures of pure and Mo-doped HAp are nanorods of few nanometers. The vibrational modes were identified using the FT-Raman and FT-IR spectroscopy. The dielectric properties were studied and the AC electrical conductivity was found to be increased with increasing the concentration of Mo ions doping in HAp. Moreover, antimicrobial studies were also carried out to understand the anti-bacterial and anti-fungi properties. The results suggest that it may be a good bio-ceramics material for bio-medical applications. Mo-doped HAp was subjected to the gamma irradiation produced from Cs-137 (662keV) and its related parameters such as linear absorption coefficient, the half-value layer (HVL) and the tenth value layer TVL were calculated and analyzed. Copyright © 2017 Elsevier B.V. All rights reserved.
Energy Technology Data Exchange (ETDEWEB)
More, Chaitali V., E-mail: chaitalimore89@gmail.com; Lokhande, Rajkumar M.; Pawar, Pravina P., E-mail: pravinapawar4@gmail.com [Department of physics, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad 431004 (India)
2016-05-06
Mass attenuation coefficients of amino acids such as n-acetyl-l-tryptophan, n-acetyl-l-tyrosine and d-tryptophan were measured in the energy range 0.122-1.330 MeV. NaI (Tl) scintillation detection system was used to detect gamma rays with a resolution of 8.2% at 0.662 MeV. The measured attenuation coefficient values were then used to determine the mass energy-absorption coefficients (σ{sub a,en}) and average atomic energy-absorption cross sections (μ{sub en}/ρ) of the amino acids. Theoretical values were calculated based on XCOM data. Theoretical and experimental values are found to be in good agreement.
Characteristics of nasal-associated lymphoid tissue (NALT) and nasal absorption capacity in chicken.
Kang, Haihong; Yan, Mengfei; Yu, Qinghua; Yang, Qian
2013-01-01
As the main mucosal immune inductive site of nasal cavity, nasal-associated lymphoid tissue (NALT) plays an important role in both antigen recognition and immune activation after intranasal immunization. However, the efficiency of intranasal vaccines is commonly restricted by the insufficient intake of antigen by the nasal mucosa, resulting from the nasal mucosal barrier and the nasal mucociliary clearance. The distribution of NALT and the characteristic of nasal cavity have already been described in humans and many laboratory rodents, while data about poultry are scarce. For this purpose, histological sections of the chicken nasal cavities were used to examine the anatomical structure and histological characteristics of nasal cavity. Besides, the absorptive capacity of chicken nasal mucosa was also studied using the materials with different particle size. Results showed that the NALT of chicken was located on the bottom of nasal septum and both sides of choanal cleft, which mainly consisted of second lymphoid follicle. A large number of lymphocytes were distributed under the mucosal epithelium of inferior nasal meatus. In addition, there were also diffuse lymphoid tissues located under the epithelium of the concha nasalis media and the walls of nasal cavity. The results of absorption experiment showed that the chicken nasal mucosa was capable to absorb trypan blue, OVA, and fluorescent latex particles. Inactivated avian influenza virus (IAIV) could be taken up by chicken nasal mucosa except for the stratified squamous epithelium sites located on the forepart of nasal cavity. The intake of IAIV by NALT was greater than that of the nasal mucosa covering on non-lymphoid tissue, which could be further enhanced after intranasal inoculation combined with sodium cholate or CpG DNA. The study on NALT and nasal absorptive capacity will be benefit for further understanding of immune mechanisms after nasal vaccination and development of nasal vaccines for poultry.
Ginter, S
2000-07-01
Ultrasound (US) thermotherapy is used to treat tumours, located deep in human tissue, by heat. It features by the application of high intensity focused ultrasound (HIFU), high local temperatures of about 90 degrees C and short treating time of a few seconds. Dosage of the therapy remains a problem. To get it under control, one has to know the heat source, i.e. the amount of absorbed US power, which shows nonlinear influences. Therefore, accurate simulations are essential. In this paper, an improved simulation model is introduced which enables accurate investigations of US thermotherapy. It combines nonlinear US propagation effects, which lead to generation of higher harmonics, with a broadband frequency-power law absorption typical for soft tissue. Only the combination of both provides a reliable calculation of the generated heat. Simulations show the influence of nonlinearities and broadband damping for different source signals on the absorbed US power density distribution.
International Nuclear Information System (INIS)
Berrocal T, Mariella J.; Roberty, Nilson C.; Silva Neto, Antonio J.; Universidade Federal, Rio de Janeiro, RJ
2002-01-01
The solution of inverse problems in participating media where there is emission, absorption and dispersion of the radiation possesses several applications in engineering and medicine. The objective of this work is to estimative the coefficients of absorption and dispersion in two-dimensional heterogeneous participating media, using in independent form the Generalized Maximum Entropy and Levenberg Marquardt methods. Both methods are based on the solution of the direct problem that is modeled by the Boltzmann equation in cartesian geometry. Some cases testes are presented. (author)
Mashin, N. I.; Chernyaeva, E. A.; Tumanova, A. N.; Gafarova, L. M.
2016-03-01
A new XRF procedure for the determination of the mass absorption coefficient in thin film Ti/V and V/Ti two-layer systems has been proposed. The procedure uses easy-to-make thin-film layers of sputtered titanium and vanadium on a polymer film substrate. Correction coefficients have been calculated that take into account attenuation of primary radiation of the X-ray tube, as well as attenuation of the spectral line of the bottom layer element in the top layer.
Giver, L. P.; Gentry, B.; Schwemmer, G.; Wilkerson, T. D.
1982-01-01
Intensities were measured for 97 lines of H2O vapor between 932 and 961 nm. The lines were selected for their potential usefulness for remote laser measurements of H2O vapor in the earth's atmosphere. The spectra were obtained with several different H2O vapor abundances and N2 broadening gas pressures; the spectral resolution was 0.046/cm FWHM. Measured H2O line intensities range from 7 x 10 to the -25th to 7 x 10 to the -22nd/cm per (molecules/sq cm). H2O self-broadening coefficients were measured for 13 of these strongest lines; the mean value was 0.5/cm per atm. N2-collision-broadening coefficients were measured for 73 lines, and the average was 0.11 cm per atm HWHM. Pressure shifts in air were determined for a sample of six lines between 948 and 950 nm; these lines shift to lower frequency by an amount comparable to 0.1 of the collision-broadened widths measured in air or N2. The measured intensities of many lines of 300-000 band are much larger than expected from prior computations, in some cases by over an order of magnitude. Coriolis interactions with the stronger 201-000 band appear to be the primary cause of the enhancement of these line intensities.
Zamani, A.; Azargoshasb, T.; Niknam, E.
2017-10-01
Effects of applied magnetic field, temperature and dimensions on the optical absorption coefficients (AC) and refractive index (RI) changes of a GaAs quantum ring are investigated in the presence of both Rashba and Dresselhaus spin-orbit interactions (SOI). To this end, the finite difference method (FDM) is used in order to numerically calculate the energy eigenvalues and eigenstates of the system while the compact density matrix approach is hired to calculate the optical properties. It is shown that application of magnetic field, temperature as well as the geometrical size in the presence of spin-orbit interactions, alter the electronic structure and consequently influence the linear and third-order nonlinear optical absorption coefficients as well as the refractive index changes of the system. Results show an obvious blue shift in optical curves with enhancing external magnetic field and temperature while the increment of dimensions result in red shift.
International Nuclear Information System (INIS)
El Sherbini, A.M.; El Sherbini, Th.M.; Hegazy, H.; Cristoforetti, G.; Legnaioli, S.; Palleschi, V.; Pardini, L.; Salvetti, A.; Tognoni, E.
2005-01-01
In quantitative Laser Induced Breakdown Spectroscopy (LIBS) measurements it is essential to account for the effect of self-absorption on the emission lines intensity. In order to quantify this effect, in this paper we propose a simple method for evaluating the ratio between the actual measured line intensity and the intensity expected in absence of self-absorption and, if necessary, correcting the effect of self-absorption on line intensity. The method, based on a homogeneous plasma model, is applicable when the plasma electron density is known and in particular to lines whose Stark broadening parameter is available
International Nuclear Information System (INIS)
Polat, Recep; Icelli, Orhan
2010-01-01
In order to determine the effect of XAFS (X-ray absorption fine structure) on J zeff , we have measured μ/ρ values of compounds, which are determined by the mixture rule or the independent atomic model. Also, we want to obtain both XAFS effect and non-applicability or applicability of mixture rule. The most crucial finding in this study is that measurement of the effective atomic number is not appropriate near the absorption edge and the effective atomic number is affected by near the absorption edge. The results obtained have been compared with theoretical values. Also, the objective of this study is to show that there is a term 'J zeff ' between effective atomic numbers and absorption jump factor.
International Nuclear Information System (INIS)
Roy, Bunty Rani; Rajput, Parasmani; Jha, S.N.; Nageswara Rao, A.S.
2015-01-01
The work presents the X-ray absorption fine structure (XAFS) technique for measuring the X-ray mass attenuation coefficient of nickel metal foil in the X-ray energy range of 8271.2–8849.4 eV using scanning XAFS beam line (BL-09) at Indus-2 synchrotron radiation source facility, Raja Ramanna Centre for Advanced Technology (RRCAT) at Indore, India. The result represents the X-ray mass attenuation coefficient data for 0.02 mm thick Ni metal foil in the XAFS region of Ni K-edge. However, the results are compared to theoretical values using X-COM. There is a maximum deviation which is found exactly near the K-edge jump and decreases as we move away from the absorption edge. Oscillatory structure appears just above the observed absorption edge i.e., 8348.7 eV and is confined to around 250 eV above the edge. - Highlights: • Mass attenuation coefficient measurements of nickel using synchrotron radiation. • The measurements were taken exactly near the Ni K-edge at an energy step of 1 eV. • A maximum deviation is found near the K-edge
Buhr, H; Büermann, L; Gerlach, M; Krumrey, M; Rabus, H
2012-12-21
For the first time the absolute photon mass energy-absorption coefficient of air in the energy range of 10 to 60 keV has been measured with relative standard uncertainties below 1%, considerably smaller than those of up to 2% assumed for calculated data. For monochromatized synchrotron radiation from the electron storage ring BESSY II both the radiant power and the fraction of power deposited in dry air were measured using a cryogenic electrical substitution radiometer and a free air ionization chamber, respectively. The measured absorption coefficients were compared with state-of-the art calculations and showed an average deviation of 2% from calculations by Seltzer. However, they agree within 1% with data calculated earlier by Hubbell. In the course of this work, an improvement of the data analysis of a previous experimental determination of the mass energy-absorption coefficient of air in the range of 3 to 10 keV was found to be possible and corrected values of this preceding study are given.
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Baghramyan, H.M.; Barseghyan, M.G.; Kirakosyan, A.A.; Restrepo, R.L.; Duque, C.A.
2013-01-01
The linear and nonlinear intra-band optical absorption coefficients in GaAs/Ga 1−x Al x As two-dimensional concentric double quantum rings are investigated. Taking into account the combined effects of hydrostatic pressure and aluminum concentration the energies of the ground (n=1,l=0) and the first excited state (n=2,l=1) have been found using the effective mass approximation and the transfer matrix formalism. The energies of these states and the corresponding threshold energy of the intra-band optical transitions are examined as a function of hydrostatic pressure and aluminum concentration for different sizes of the structure. We also investigated the dependencies of the linear, nonlinear, and total optical absorption coefficients as functions of the incident photon energy for different values of hydrostatic pressure, aluminum concentration, sizes of the structure, and incident optical intensity. Its is found that the effects of the hydrostatic pressure and the aluminum concentration lead to a shifting of the resonant peaks of the intra-band optical spectrum. - Highlights: ► Linear and nonlinear intra-band absorption in quantum rings. ► Threshold energy strongly depends on the hydrostatic pressure. ► Threshold energy strongly depends on the stoichiometry and sizes of structure. ► Optical absorption is affected by the incident optical intensity.
Satoliya, Anil Kumar; Vyas, B. M.; Shekhawat, M. S.
2018-05-01
The first time satellite space based measurement of atmospheric black carbon (BC) aerosols scattering coefficient at 550nm (BC SC at 550nm), dust aerosols scattering and dust aerosols extinction coefficient (DSC at 550nm and DEC at 550nm) parameters have been used to understand their long term trend of natural and anthropogenic aerosols behavior with its close association with ground based measured precipitation parameters such as Total Rain Fall (TRF), and Total Number of Rainy Days (TNRD) for the same period over western Indian regions concerned to the primary aerosols sources of natural activities. The basic objective of this study is an attempt to investigate the inter-correlation between dust and black carbon aerosols loading characteristics with a variation of rainfall pattern parameters as indirect aerosols induced effect i.e., aerosols-cloud interaction. The black carbon aerosols generated by diverse anthropogenic or human made activities are studied by choosing of measured atmospheric BC SC at 550nm parameter, whereas desert dust mineral aerosols primarily produced by varieties of natural activities pre-dominated of dust mineral desert aerosols mainly over Thar desert influenced area of hot climate and rural tropical site are investigated by selecting DSC at 550nm and DEC at 550nm of first semi-urban site i.e., Udaipur (UDP, 24.6°N, 73.35°E, 580m above surface level (asl)) situated in southern Rajasthan part as well as over other two Great Indian Thar desert locations i.e., Jaisalmer (JSM, 26.90°N, 69.90°E, 220m asl)) and Bikaner (BKN, 28.03°N, 73.30°E, 224m asl) located in the vicinity of the Thar desert region situated in Rajasthan state of the western Indian region. The source of the present study would be collection of longer period of monthly values of the above parameters of spanning 35 years i.e., 1980 to 2015. Such types of atmospheric aerosols-cloud monsoon interaction investigation is helpful in view of understanding their direct and
Determination of cadmium in bovine tissue by spectrophotometry of atomic absorption
International Nuclear Information System (INIS)
Gonzalez Zeledon, Mauricio
2004-01-01
The present work utilized the suggested method by Food Safety and Inspection Service (FSIS) for the analysis of cadmium in animal tissue, it was adapted by the Toxicology's Laboratory of MAG, where the project was organized. This method consist of a burning of sample and the instrumental analysis by means of the atomic absorption's technique. In the study there were determined parameters of carrying out of the analytical methodology, it was getting the following values: linearity : 0,020 -1,0 mg/L; homogeneity of the model: homoscedastic; limit of detection (LD) : 0,0049 mg/kg (4,9 μg/Kg); limit of quantification (LC): 0,016 μg/L (16 mg/kg); sensibility of calibration: 0,243 A * L/gm; analytical sensibility: 105 L/mg; instrumental repetitively: [es
Remarkable optical red shift and extremely high optical absorption coefficient of V-Ga co-doped TiO2
Deng, Quanrong; Han, Xiaoping; Gao, Yun; Shao, Guosheng
2012-07-01
A first attempt has been made to study the effect of codoping of transition metal and sp metal on the electronic structure and associated optical properties of TiO2, through V-Ga codoped thin films. V-Ga codoped rutile TiO2 films were fabricated on fused quartz substrates using pulsed laser ablation, followed by heat treatment at high temperatures. Gigantic redshift in the optical absorption edge was observed in V-Ga co-doped TiO2 materials, from UV to infrared region with high absorption coefficient. Through combined structural characterization and theoretical modeling, this is attributed to the p-d hybridization between the two metals. This leads to additional energy bands to overlap with the minimum of the conduction band, leading to remarkably narrowed band gap free of mid-gap states. The direct-gap of the co-doped phase is key to the remarkably high optical absorption coefficient of the coped titania.
Bernat, Amir S.; Bar-Am, Kfir; Cataldo, Leigh; Bolton, Frank J.; Kahn, Bruce S.; Levitz, David
2018-02-01
Cervical cancer is a leading cause of death for women in low resource settings. In order to better detect cervical dysplasia, a low cost multi-spectral colposcope was developed utilizing low costs LEDs and an area scan camera. The device is capable of both traditional colposcopic imaging and multi-spectral image capture. Following initial bench testing, the device was deployed to a gynecology clinic where it was used to image patients in a colposcopy setting. Both traditional colposcopic images and spectral data from patients were uploaded to a cloud server for remote analysis. Multi-spectral imaging ( 30 second capture) took place before any clinical procedure; the standard of care was followed thereafter. If acetic acid was used in the standard of care, a post-acetowhitening colposcopic image was also captured. In analyzing the data, normal and abnormal regions were identified in the colposcopic images by an expert clinician. Spectral data were fit to a theoretical model based on diffusion theory, yielding information on scattering and absorption parameters. Data were grouped according to clinician labeling of the tissue, as well as any additional clinical test results available (Pap, HPV, biopsy). Altogether, N=20 patients were imaged in this study, with 9 of them abnormal. In comparing normal and abnormal regions of interest from patients, substantial differences were measured in blood content, while differences in oxygen saturation parameters were more subtle. These results suggest that optical measurements made using low cost spectral imaging systems can distinguish between normal and pathological tissues.
International Nuclear Information System (INIS)
Kerur, B.R.; Thontadarya, S.R.; Hanumaiah, B.
1994-01-01
The x-ray attenuation coefficients for three elements and for eight compounds are determined, adopting the method developed by employing a proportional counter, with a view to study the effect of fine structure on the mass attenuation coefficient values using Mn K α and Cu K α x-rays derived from K x-ray emitters, 55 Fe and 65 Zn radioactive sources, by a differential absorption technique. It is experimentally established that a small difference in energy between K α1 and K α2 (11 eV in the case of Mn K α and 24 eV in the case of the Cu K α x-ray) is inconsequential by comparing the measured and theoretical values of μ/ρ for standard elements, aluminium, copper and tantalum. The effect of fine structure on μ/ρ values is studied using the compounds containing one element with its absorption edge close to the incident photon energy. Results obtained in the present investigation show the nonvalidity of the mixture rule above the edge and also below the edge, ranging from about 600 eV below the edge to about 1500 eV about the edge. The contribution of resonance Raman scattering to the attenuation coefficient and indications to the presence of pre-edge structure similar to EXAFS are discussed. (author)
The absorption, tissue distribution and excretion of Di-n-Octylten dichloride in rats
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Penninks, A.H.; Hilgers, Luuk; Seinen, Willem
1987-01-01
In this study the absorption, tissue distribution and excretion of 14 C-labeled di-n-octyltin dichloride ([ 14 C] DOTC) in rats were investigated after oral and intravenous (i.v.) administration with 6.3 mg [ 14 C] DOTC/Kg body weight, the relative tissue accumulation was found to be the same after oral and i.v. dosage. The highest amount of radioactivity was found in liver and kidney, and to a lesser degree in adrenal, pituitary and thyroid glands. The lowest activity was recovered from blood and brain. No selective accumulation was observed in thymus, although it has been reported that thymus atrophy is the most sensitive parameter of DOTC toxicity in rats. For all tissues a time dependent decrease in radioactivity was found, except for kidney. The excretion of radioactivity in feces and urine was determined after a single i.v. or oral dose of l.2 and 2 mg [ 14 C] DOTC, respectively. After i.v. administration most of the radioactivity was excreted in the feces which was characterized by a biphasic excretion pattern. In orally treated rats more than 80% of the radioactivity was already excreted in the feces during the first day after administration. This indicated that only a small part of the DOTC was absorbed, which was calculated to be approximately 20% of the dose. Similar half-life values of 8.3 and 8.9 days were obtained from the fecal excretion of radioactivity after the i.v. and oral administration, respectively. The urinary excretion of radioactivity appeared to be independent of the body burden, since the daily amount of radioactivity excreted in urine was nearly the same independent of the route of administration as well as the time after administration. 26 refs. (author)
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Franzini, M.; Leoni, L.; Saitta, M.
1976-01-01
By utilizing a reflection geometry, an accurate mass absorption coefficient of a sample can be determined by measuring the Ag Kα Compton intensity. Intensities of Ag Kα Compton scattered radiation have been collected by using either the usual reflection geometry of a Philips PW 1450 automatic x-ray spectrometer or a more refined reflection geometry, achieved on a Philips PW 1540/10A manual x-ray spectrometer. The experimental results have shown that the relationship between the Ag Kα Compton intensity and the mass absorption is a logarithmic function. The experimental results are not in agreement with those reported in literature, but a theoretical explanation to account for this fact has not been achieved as yet. (author)
Lee, Zhong-Ping; Carder, Kendall L.
2001-01-01
A multi-band analytical (MBA) algorithm is developed to retrieve absorption and backscattering coefficients for optically deep waters, which can be applied to data from past and current satellite sensors, as well as data from hyperspectral sensors. This MBA algorithm applies a remote-sensing reflectance model derived from the Radiative Transfer Equation, and values of absorption and backscattering coefficients are analytically calculated from values of remote-sensing reflectance. There are only limited empirical relationships involved in the algorithm, which implies that this MBA algorithm could be applied to a wide dynamic range of waters. Applying the algorithm to a simulated non-"Case 1" data set, which has no relation to the development of the algorithm, the percentage error for the total absorption coefficient at 440 nm a (sub 440) is approximately 12% for a range of 0.012 - 2.1 per meter (approximately 6% for a (sub 440) less than approximately 0.3 per meter), while a traditional band-ratio approach returns a percentage error of approximately 30%. Applying it to a field data set ranging from 0.025 to 2.0 per meter, the result for a (sub 440) is very close to that using a full spectrum optimization technique (9.6% difference). Compared to the optimization approach, the MBA algorithm cuts the computation time dramatically with only a small sacrifice in accuracy, making it suitable for processing large data sets such as satellite images. Significant improvements over empirical algorithms have also been achieved in retrieving the optical properties of optically deep waters.
Oishi, Masaki; Shinozaki, Tomohisa; Hara, Hikaru; Yamamoto, Kazunuki; Matsusue, Toshio; Bando, Hiroyuki
2018-03-01
The two-photon absorption coefficient β in InP has been measured in the wavelength range of 1640 to 1800 nm by the Z-scan technique in relatively thick materials. The values of β have been evaluated from the fit to the equation including the spatial and temporal profiles of the focused Gaussian beam. The polarization dependence of β has also been measured. The dependence has been expressed very well by the expression of β with the imaginary part of the third-order nonlinear susceptibility tensor χ(3).
Kitamura, Ryunosuke; Inagaki, Tetsuya; Tsuchikawa, Satoru
2016-02-22
The true absorption coefficient (μa) and reduced scattering coefficient (μ´s) of the cell wall substance in Douglas fir were determined using time-of-flight near infrared spectroscopy. Samples were saturated with hexane, toluene or quinolone to minimize the multiple reflections of light on the boundary between pore-cell wall substance in wood. μ´s exhibited its minimum value when the wood was saturated with toluene because the refractive index of toluene is close to that of the wood cell wall substance. The optical parameters of the wood cell wall substance calculated were μa = 0.030 mm(-1) and μ´s= 18.4 mm(-1). Monte Carlo simulations using these values were in good agreement with the measured time-resolved transmittance profiles.
Midgley, Stewart; Schleich, Nanette
2015-05-01
A novel method for dual-energy X-ray analysis (DEXA) is tested using measurements of the X-ray linear attenuation coefficient μ. The key is a mathematical model that describes elemental cross sections using a polynomial in atomic number. The model is combined with the mixture rule to describe μ for materials, using the same polynomial coefficients. Materials are characterized by their electron density Ne and statistical moments Rk describing their distribution of elements, analogous to the concept of effective atomic number. In an experiment with materials of known density and composition, measurements of μ are written as a system of linear simultaneous equations, which is solved for the polynomial coefficients. DEXA itself involves computed tomography (CT) scans at two energies to provide a system of non-linear simultaneous equations that are solved for Ne and the fourth statistical moment R4. Results are presented for phantoms containing dilute salt solutions and for a biological specimen. The experiment identifies 1% systematic errors in the CT measurements, arising from third-harmonic radiation, and 20-30% noise, which is reduced to 3-5% by pre-processing with the median filter and careful choice of reconstruction parameters. DEXA accuracy is quantified for the phantom as the mean absolute differences for Ne and R4: 0.8% and 1.0% for soft tissue and 1.2% and 0.8% for bone-like samples, respectively. The DEXA results for the biological specimen are combined with model coefficients obtained from the tabulations to predict μ and the mass energy absorption coefficient at energies of 10 keV to 20 MeV.
International Nuclear Information System (INIS)
Loureiro, E.C.M.; Khoury, H.; Lima, F.R.A.
1998-01-01
The increasing utilization of oral X-rays, specially in youngsters and children, prompts the assessment of equivalent doses in their organs and tissues. With this purpose, Monte Carlo code was adopted to simulate an X-ray source irradiating phantoms of the MIRD-5 type with different ages (10, 15 and 40 years old) to calculate the conversion coefficients which transform the exposure at skin to equivalent doses at several organs and tissues of interest. In order to check the computer program, simulations were performed for adult patients using the original code (ADAM,FOR developed by GSF Germany) and the adapted program (MCDRO,PAS). Good agreement between results obtained by both programs was observed. Applications to incisive, canine and molar teeth were simulated. The conversion factors were calculated for the following organs and tissues: thyroid, active bone marrow (head and whole body), bone (facial skeleton, cranium and whole body), skin (head and whole body) and crystalline. Based on the obtained results, it follows that the younger the patient and the langer the field area, the higher the doses in assessed organs and tissues
Wan, Jiangbo; Zhang, Guoan; Qiu, Yuxuan; Wen, Chunquan; Fu, Tairan
2016-05-01
This study aimed to further explore heat dissipation by blood circulation and airway tissue heat absorption in an inhalational thermal injury model. Twelve adult male Beagle dogs were divided into four groups to inhale heated air for 10min: the control group, group I (100.5°C), group II (161.5°C), and group III (218°C). The relative humidity and temperature of the inhaled heated air were measured in the heating tube and trachea, as were blood temperatures and flow velocities in both common jugular veins. Formulas were used to calculate the total heat quantity reduction of the heated air, heat dissipation by the blood, and airway tissue heat absorption. The blood temperatures of both the common jugular veins increased by 0.29°C±0.07°C to 2.96°C±0.24°C and the mean blood flow volume after injury induction was about 1.30-1.74 times greater than before injury induction. The proportions of heat dissipated by the blood and airway tissue heat absorption were 68.92%±14.88% and 31.13%±14.87%, respectively. The heat dissipating ability of the blood circulation was demonstrated and improved upon along with tissue heat absorption owing to increased regional blood flow. Copyright © 2015 Elsevier Ltd and ISBI. All rights reserved.
Hu, Haiyang; Wang, Qiang
2018-07-01
A new strategy for grouping spectral absorption coefficients, considering the influences of both temperature and species mole ratio inhomogeneities on correlated-k characteristics of the spectra of gas mixtures, has been deduced to match the calculation method of spectral overlap parameter used in multiscale multigroup wide band k-distribution model. By comparison with current spectral absorption coefficient grouping strategies, for which only the influence of temperature inhomogeneity on the correlated-k characteristics of spectra of single species was considered, the improvements in calculation accuracies resulting from the new grouping strategy were evaluated using a series of 0D cases in which radiance under 3-5-μm wave band emitted by hot combustion gas of hydrocarbon fuel was attenuated by atmosphere with quite different temperature and mole ratios of water vapor and carbon monoxide to carbon dioxide. Finally, evaluations are presented on the calculation of remote sensing thermal images of transonic hot jet exhausted from a chevron ejecting nozzle with solid wall cooling system.
Martínez-Orozco, J. C.; Rodríguez-Magdaleno, K. A.; Suárez-López, J. R.; Duque, C. A.; Restrepo, R. L.
2016-04-01
In this work we present theoretical results for the electronic structure as well as for the absorption coefficient and relative refractive index change for an asymmetric double δ-doped like confining potential in the active region of a Multiple Independent Gate Field Effect Transistor (MIGFET) system. We model the potential profile as a double δ-doped like potential profile between two Schottky (parabolic) potential barriers that are just the main characteristics of the MIGFET configuration. We investigate the effect of external electromagnetic fields in this kind of quantum structures, in particular we applied a homogeneous constant electric field in the growth direction z as well as a homogeneous constant magnetic field in the x-direction. In general we conclude that by applying electromagnetic fields we can modulate the resonant peaks of the absorption coefficient as well as their energy position. Also with such probes it is possible to control the nodes and amplitude of the relative refractive index changes related to resonant intersubband optical transitions.
Freitas, Alex A; Limbu, Kriti; Ghafourian, Taravat
2015-01-01
Volume of distribution is an important pharmacokinetic property that indicates the extent of a drug's distribution in the body tissues. This paper addresses the problem of how to estimate the apparent volume of distribution at steady state (Vss) of chemical compounds in the human body using decision tree-based regression methods from the area of data mining (or machine learning). Hence, the pros and cons of several different types of decision tree-based regression methods have been discussed. The regression methods predict Vss using, as predictive features, both the compounds' molecular descriptors and the compounds' tissue:plasma partition coefficients (Kt:p) - often used in physiologically-based pharmacokinetics. Therefore, this work has assessed whether the data mining-based prediction of Vss can be made more accurate by using as input not only the compounds' molecular descriptors but also (a subset of) their predicted Kt:p values. Comparison of the models that used only molecular descriptors, in particular, the Bagging decision tree (mean fold error of 2.33), with those employing predicted Kt:p values in addition to the molecular descriptors, such as the Bagging decision tree using adipose Kt:p (mean fold error of 2.29), indicated that the use of predicted Kt:p values as descriptors may be beneficial for accurate prediction of Vss using decision trees if prior feature selection is applied. Decision tree based models presented in this work have an accuracy that is reasonable and similar to the accuracy of reported Vss inter-species extrapolations in the literature. The estimation of Vss for new compounds in drug discovery will benefit from methods that are able to integrate large and varied sources of data and flexible non-linear data mining methods such as decision trees, which can produce interpretable models. Graphical AbstractDecision trees for the prediction of tissue partition coefficient and volume of distribution of drugs.
Esteves, Freddy; Moutinho, Carla; Matos, Carla
2013-06-01
Absorption and consequent therapeutic action are key issues in the development of new drugs by the pharmaceutical industry. In this sense, different models can be used to simulate biological membranes to predict the absorption of a drug. This work compared the octanol/water and the liposome/water models. The parameters used to relate the two models were the distribution coefficients between liposomes and water and octanol and water and the fraction of drug orally absorbed. For this study, 66 drugs were collected from literature sources and divided into four groups according to charge and ionization degree: neutral; positively charged; negatively charged; and partially ionized/zwitterionic. The results show a satisfactory linear correlation between the octanol and liposome systems for the neutral (R²= 0.9324) and partially ionized compounds (R²= 0.9367), contrary to the positive (R²= 0.4684) and negatively charged compounds (R²= 0.1487). In the case of neutral drugs, results were similar in both models because of the high fraction orally absorbed. However, for the charged drugs (positively, negatively, and partially ionized/zwitterionic), the liposomal model has a more-appropriate correlation with absorption than the octanol model. These results show that the neutral compounds only interact with membranes through hydrophobic bonds, whereas charged drugs favor electrostatic interactions established with the liposomes. With this work, we concluded that liposomes may be a more-appropriate biomembrane model than octanol for charged compounds.
International Nuclear Information System (INIS)
Liu Guohua; Chen Guosheng; Cai Huiyi
1998-01-01
The experiment was conducted to determine the effects of heat stress on ascorbic acid nutritional physiology of broilers with radioisotope technology. 3 H-Vc was fed to broilers and then the blood, liver, kidney, breast muscle, and excreta were sampled to determine the dynamic absorption process, the tissue distribution and the utilization efficiency of vitamin C. The results indicated that the absorption, metabolism and mobilization of supplemented vitamin C in broilers with heat stress was faster than that in broilers without heat stress. However, the utilization efficiency of supplemented vitamin C in broilers with heat stress was not higher than that of broilers without heat stress
International Nuclear Information System (INIS)
RAZAFINTSALAMA, V.T.
2009-01-01
Heavy metals are classified among the inorganic compounds. The latter type of metal is found in rocks, fertilizers, urban mud but may also originate from the atmospheric pollution. A particular characteristic of heavy metals is their bioaccumulation in the food chain. Therefore, lead and cadmium, which are classified as heavy metals may be easily found in animal products and can lead to food poisoning if their concentrations are higher than the maximum permissible values as requested by international agencies such as the c odex alimentarius . The values are set down and differ according to types of food for human consuption and the trading companies take action accordingly. Therefore, it is necessary to set up a quality control system through analytical laboratory measurements and testings. This study underlies the method of determination of lead, cadmium and iron in animal tissues by atomic absorption spectrometry. The results showed that the method is sensitive and reliable. For each analyte, the Z-score lies between -2 and 2, indicating that the method is working properly. The analytical results showed that: (i) only beef and chicken meats and beef liver contain lead [0,09μg.g - 1; 0,29μg.g - 1]. The limit value of 0,1μg.g - 1 is almost reached in beef and chicken meats, (ii) as far as cadmium is concerned, the five studied samples contain this analyte [0,02μg.g - 1; 0,9μg.g - 1]. Except the chicken liver of which the concentration (0,15μg.g - 1) exceeds the maximum permissible value (0,1μg.g - 1), the others are in conformity with the standards and appropriate to be consumed,(iii) iron is higher in the liver and kidney samples: beef liver 282mg.g - 1, chicken liver 250 mg.g - 1, pork kidney 247mg.g - 1. The study also showed that the calcium concentration in animal tissues is low and they can be classified as poor-calcium food. [fr
Velicka, M.; Urboniene, V.; Ceponkus, J.; Pucetaite, M.; Jankevicius, F.; Sablinskas, V.
2015-08-01
We present a novel approach to the detection of cancerous kidney tissue areas by measuring vibrational spectra (IR absorption or SERS) of intercellular fluid taken from the tissue. The method is based on spectral analysis of cancerous and normal tissue areas in order to find specific spectral markers. The samples were prepared by sliding the kidney tissue over a substrate - surface of diamond ATR crystal in case of IR absorption or calcium fluoride optical window in case of SERS. For producing the SERS signal the dried fluid film was covered by silver nanoparticle colloidal solution. In order to suppress fluorescence background the measurements were performed in the NIR spectral region with the excitation wavelength of 1064 nm. The most significant spectral differences - spectral markers - were found in the region between 400 and 1800 cm-1, where spectral bands related to various vibrations of fatty acids, glycolipids and carbohydrates are located. Spectral markers in the IR and SERS spectra are different and the methods can complement each other. Both of them have potential to be used directly during surgery. Additionally, IR absorption spectroscopy in ATR mode can be combined with waveguide probe what makes this method usable in vivo.
Nakajo, Masanori; Fukukura, Yoshihiko; Hakamada, Hiroto; Yoneyama, Tomohide; Kamimura, Kiyohisa; Nagano, Satoshi; Nakajo, Masayuki; Yoshiura, Takashi
2018-02-22
Apparent diffusion coefficient (ADC) histogram analyses have been used to differentiate tumor grades and predict therapeutic responses in various anatomic sites with moderate success. To determine the ability of diffusion-weighted imaging (DWI) with a whole-tumor ADC histogram analysis to differentiate benign peripheral neurogenic tumors (BPNTs) from soft tissue sarcomas (STSs). Retrospective study, single institution. In all, 25 BPNTs and 31 STSs. Two-b value DWI (b-values = 0, 1000s/mm 2 ) was at 3.0T. The histogram parameters of whole-tumor for ADC were calculated by two radiologists and compared between BPNTs and STSs. Nonparametric tests were performed for comparisons between BPNTs and STSs. P histogram parameters except kurtosis and entropy differed significantly between BPNTs and STSs. 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018. © 2018 International Society for Magnetic Resonance in Medicine.
Eleftheriadis, Konstantinos; Kalogridis, Athina-Cerise; Vratolis, Sterios; Fiebig, Markus
2016-04-01
Light absorbing carbon in atmospheric aerosol plays a critical role in radiative forcing and climate change. Despite the long term measurements across the Arctic, comparing data obtained by a variety of methods across stations requires caution. A method for extracting the aerosol absorption coefficient from data obtained over the decades by filter based instrument is still under development. An IASOA Aerosol working group has been initiated to address this and other cross-site aerosol comparison opportunities. Continuous ambient measurements of EBC/light attenuation by means of a Magee Sci. AE-31 aethalometer operating at the Zeppelinfjellet station (474 m asl; 78°54'N, 11°53'E), Ny Ålesund, Svalbard, have been available since 2001 (Eleftheriadis et al, 2009), while a new aethalometer model (AE33, Drinovec et al, 2014) has been installed to operate in parallel from the same inlet since June 2015. Measurements are recorded by a Labview routine collecting all available parameters reported by the two instrument via RS232 protocol. Data are reported at 1 and 10 minute intervals as averages for EBC (μg m-3) and aerosol absorption coefficients (Mm-1) by means of routine designed to report Near Real Time NRT data at the EBAS WDCA database (ebas.nilu.no) Results for the first 6 month period are reported here in an attempt to evaluate comparative performance of the two instruments in terms of their response with respect to the variable aerosol load of light absorbing carbon during the warm and cold seasons found in the high arctic. The application of available conversion schemes for obtaining the absorption coefficient by the two instruments is found to demonstrate a marked difference in their output. During clean periods of low aerosol load (EBC origin was also conducted. Drinovec, L., Močnik, G., Zotter, P., Prévôt, A. S. H., Ruckstuhl, C., Coz, E., Rupakheti, M., Sciare, J., Müller, T., Wiedensohler, A., and Hansen, A. D. A. The "dual-spot" Aethalometer: an
Yu, Xue; Lee, Elaine Yuen Phin; Lai, Vincent; Chan, Queenie
2014-07-01
To evaluate the correlation between standardized uptake value (SUV) (tissue metabolism) and apparent diffusion coefficient (ADC) (water diffusivity) in peritoneal metastases. Patients with peritoneal dissemination detected on (18)F-fluorodeoxyglucose positron emission tomography combined with computed tomography (FDG-PET/CT) were prospectively recruited for MRI examinations with informed consent and the study was approved by the local Institutional Review Board. FDG-PET/CT, diffusion-weighted imaging (DWI), MRI, and DWI/MRI images were independently reviewed by two radiologists based on visual analysis. SUVmax/SUVmean and ADCmin/ADCmean were obtained manually by drawing ROIs over the peritoneal metastases on FDG-PET/CT and DWI, respectively. Diagnostic characteristics of each technique were evaluated. Pearson's coefficient and McNemar and Kappa tests were used for statistical analysis. Eight patients were recruited for this prospective study and 34 peritoneal metastases were evaluated. ADCmean was significantly and negatively correlated with SUVmax (r = -0.528, P = 0.001) and SUVmean (r = -0.548, P = 0.001). ADCmin had similar correlation with SUVmax (r = -0.508, P = 0.002) and SUVmean (r = -0.513, P = 0.002). DWI/MRI had high diagnostic performance (accuracy = 98%) comparable to FDG-PET/CT, in peritoneal metastasis detection. Kappa values were excellent for all techniques. There was a significant inverse correlation between SUV and ADC. © 2013 Wiley Periodicals, Inc.
International Nuclear Information System (INIS)
McKim, J.; Schmieder, P.; Veith, G.
1985-01-01
An in vivo fish preparation was used that allowed a direct measure of the transport rates of 14 different organic chemicals across the gills of rainbow trout (Salmo gairdneri). The chemicals, all C14 labeled, were selected from five classes, encompassing a range of octanol-water partition coefficient (log P) values, from 0.23 (ethyl formate) to 7.5 (mirex). The uptake efficiency (extraction efficiency) of each chemical was determined by monitoring the inspired and expired water of trout exposed to each chemical over an exposure period of 1 to 6 hr. The mean gill extraction efficiency for all chemicals tested varied from a low of 7% to a high of 60%, extracted in a single pall of the chemical across the gills. The extraction efficiency of chemicals with log P or 1 or less were low and showed no relationship to log P. These low extraction efficiencies seen at log P of 1 and below with molecular weights below 100 were indicative of aqueous pore transport. The mean extraction efficiency for chemicals with log P values of 1 to 3 seemed to vary directly with log P, to a maximum of slightly greater than 60%, suggesting that uptake was controlled by the lipid membrane. The mean extraction efficiency for chemicals with log P of 3 to 6 was independent of log P and remained at 60%, which suggested that gill uptake was controlled by aqueous diffusion rates rather than gill membrane permeability. The mean extraction efficiency with mirex (log P . 7.5) decreased to 20%
DEFF Research Database (Denmark)
Manohara, S.R.; Hanagodimath, S.M.; Gerward, Leif
2010-01-01
Gamma ray energy-absorption buildup factors were computed using the five-parameter geometric progression (G-P) fitting formula for seven thermoluminescent dosimetric (TLD) materials in the energy range 0.015-15 MeV, and for penetration depths up to 40 mfp (mean free path). The generated energy-absorption...
Schwarz, M L R; Schneider-Wald, B; Krase, A; Richter, W; Reisig, G; Kreinest, M; Heute, S; Pott, P P; Brade, J; Schütte, A
2012-10-01
Values for the friction coefficient of articular cartilage are given in ranges of percentage and lower and are calculated as a quotient of the friction force and the perpendicular loading force acting on it. Thus, a sophisticated system has to be provided for analysing the friction coefficient under different conditions in particular when cartilage should be coupled as friction partner. It is possible to deep-freeze articular cartilage before measuring the friction coefficient as the procedure has no influence on the results. The presented tribological system was able to distinguish between altered and native cartilage. Furthermore, tissue engineered constructs for cartilage repair were differentiated from native cartilage probes by their friction coefficient. In conclusion a tribological equipment is presented to analyze the friction coefficient of articular cartilage, in vivo generated cartilage regenerates and in vitro tissue engineered constructs regarding their biomechanical properties for quality assessment.
International Nuclear Information System (INIS)
Rojas-Briseño, J.G.; Martínez-Orozco, J.C.; Rodríguez-Vargas, I.; Mora-Ramos, M.E.; Duque, C.A.
2013-01-01
In this work we are reporting the energy level spectrum for a quantum system consisting of an n-type double δ-doped quantum well with a Schottky barrier potential in a Gallium Arsenide matrix. The calculated states are taken as the basis for the evaluation of the linear and third-order nonlinear contributions to the optical absorption coefficient and to the relative refractive index change, making particular use of the asymmetry of the potential profile. These optical properties are then reported as a function of the Schottky barrier height (SBH) and the separation distance between the δ-doped quantum wells. Also, the effects of the application of hydrostatic pressure are studied. The results show that the amplitudes of the resonant peaks are of the same order of magnitude of those obtained in the case of single δ-doped field effect transistors; but tailoring the asymmetry of the confining potential profile allows the control the resonant peak positions
Energy Technology Data Exchange (ETDEWEB)
Rojas-Briseño, J.G.; Martínez-Orozco, J.C.; Rodríguez-Vargas, I. [Unidad Académica de Física, Universidad Autónoma de Zacatecas, Calzada Solidaridad esquina con Paseo la Bufa S/N, C.P. 98060, Zacatecas, Zac. (Mexico); Mora-Ramos, M.E. [Facultad de Ciencias, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, CP 62209, Cuernavaca, Morelos (Mexico); Instituto de Física, Universidad de Antioquia, AA 1226, Medellín (Colombia); Duque, C.A., E-mail: cduque@fisica.udea.edu.co [Instituto de Física, Universidad de Antioquia, AA 1226, Medellín (Colombia)
2013-09-01
In this work we are reporting the energy level spectrum for a quantum system consisting of an n-type double δ-doped quantum well with a Schottky barrier potential in a Gallium Arsenide matrix. The calculated states are taken as the basis for the evaluation of the linear and third-order nonlinear contributions to the optical absorption coefficient and to the relative refractive index change, making particular use of the asymmetry of the potential profile. These optical properties are then reported as a function of the Schottky barrier height (SBH) and the separation distance between the δ-doped quantum wells. Also, the effects of the application of hydrostatic pressure are studied. The results show that the amplitudes of the resonant peaks are of the same order of magnitude of those obtained in the case of single δ-doped field effect transistors; but tailoring the asymmetry of the confining potential profile allows the control the resonant peak positions.
Crowe, Iain F; Clark, Nicholas; Hussein, Siham; Towlson, Brian; Whittaker, Eric; Milosevic, Milan M; Gardes, Frederic Y; Mashanovich, Goran Z; Halsall, Matthew P; Vijayaraghaven, Aravind
2014-07-28
We examine the near-IR light-matter interaction for graphene integrated cavity ring resonators based on silicon-on-insulator (SOI) race-track waveguides. Fitting of the cavity resonances from quasi-TE mode transmission spectra reveal the real part of the effective refractive index for graphene, n(eff) = 2.23 ± 0.02 and linear absorption coefficient, α(gTE) = 0.11 ± 0.01dBμm(-1). The evanescent nature of the guided mode coupling to graphene at resonance depends strongly on the height of the graphene above the cavity, which places limits on the cavity length for optical sensing applications.
International Nuclear Information System (INIS)
Porras-Chaverri, M; Galavis, P; Bakic, P; Vetter, J
2014-01-01
Purpose: Evaluate mammographic mean glandular dose (MGD) coefficients for particular known tissue distributions using a novel formalism that incorporates the effect of the heterogeneous glandular tissue distribution, by comparing them with MGD coefficients derived from the corresponding anthropomorphic computer breast phantom. Methods: MGD coefficients were obtained using MCNP5 simulations with the currently used homogeneous assumption and the heterogeneously-layered breast (HLB) geometry and compared against those from the computer phantom (ground truth). The tissue distribution for the HLB geometry was estimated using glandularity map image pairs corrected for the presence of non-glandular fibrous tissue. Heterogeneity of tissue distribution was quantified using the glandular tissue distribution index, Idist. The phantom had 5 cm compressed breast thickness (MLO and CC views) and 29% whole breast glandular percentage. Results: Differences as high as 116% were found between the MGD coefficients with the homogeneous breast core assumption and those from the corresponding ground truth. Higher differences were found for cases with more heterogeneous distribution of glandular tissue. The Idist for all cases was in the [−0.8 − +0.3] range. The use of the methods presented in this work results in better agreement with ground truth with an improvement as high as 105 pp. The decrease in difference across all phantom cases was in the [9 − 105] pp range, dependent on the distribution of glandular tissue and was larger for the cases with the highest Idist values. Conclusion: Our results suggest that the use of corrected glandularity image pairs, as well as the HLB geometry, improves the estimates of MGD conversion coefficients by accounting for the distribution of glandular tissue within the breast. The accuracy of this approach with respect to ground truth is highly dependent on the particular glandular tissue distribution studied. Predrag Bakic discloses current
Lundquist, P; Artursson, P
2016-11-15
In this contribution, we review the molecular and physiological barriers to oral delivery of peptides and nanoparticles. We discuss the opportunities and predictivity of various in vitro systems with special emphasis on human intestine in Ussing chambers. First, the molecular constraints to peptide absorption are discussed. Then the physiological barriers to peptide delivery are examined. These include the gastric and intestinal environment, the mucus barrier, tight junctions between epithelial cells, the enterocytes of the intestinal epithelium, and the subepithelial tissue. Recent data from human proteome studies are used to provide information about the protein expression profiles of the different physiological barriers to peptide and nanoparticle absorption. Strategies that have been employed to increase peptide absorption across each of the barriers are discussed. Special consideration is given to attempts at utilizing endogenous transcytotic pathways. To reliably translate in vitro data on peptide or nanoparticle permeability to the in vivo situation in a human subject, the in vitro experimental system needs to realistically capture the central aspects of the mentioned barriers. Therefore, characteristics of common in vitro cell culture systems are discussed and compared to those of human intestinal tissues. Attempts to use the cell and tissue models for in vitro-in vivo extrapolation are reviewed. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.
Energy Technology Data Exchange (ETDEWEB)
Maglic, R [Institute of Nuclear Sciences Boris Kidric, Vinca, Beograd (Serbia and Montenegro)
1962-11-15
Reactivity of a reactor depends on production, absorption and leaking of neutrons. Change of absorption causes reactivity change, and this fact is used for determining the neutron absorption cross section for the sample inserted in the reactor core. Method for determining the absorption cross section based on reactivity change is called method of safety coefficient. Measurements of neutron absorption cross section for graphite was done in the RA reactor vertical experimental channel VK-5. taking into account the results obtained for five types of graphite this method is considered to be reliable for use. Comparison of nuclear properties of different types of graphite was done as well. Reaktivnost reaktora zavisi od proizvodnje neutrona, apsorpcije i isticanja neutrona. Promena apsorpcije izaziva promene reaktivnosti reaktora pa se ova osobina koristi za odedjivanje neutronskog apsorpcionog preseka uzorka koji se unosi u reaktor. Metoda merenja apsorpcionog preseka na bazi promene reaktivnosti nazvana je metodom koeficijenta opasnosti. Merenje apsorpcionog preseka grafita uradjeno je na reaktoru RA u vertikalnom eksperimentalnom kanalu VK-5. S obzirom na rezultate koji su dobijeni za pet vrsta grafita moze se smatrati da je opravdano koriscenje ove metode. Izvrseno je i poredjenje nuklearnih osobina pomenutih tipova grafita.
Directory of Open Access Journals (Sweden)
Pinheiro Cleber
2008-07-01
Full Text Available Abstract Background One of the current shortcomings of radiofrequency (RF tumor ablation is its limited performance in regions close to large blood vessels, resulting in high recurrence rates at these locations. Computer models have been used to determine tissue temperatures during tumor ablation procedures. To simulate large vessels, either constant wall temperature or constant convective heat transfer coefficient (h have been assumed at the vessel surface to simulate convection. However, the actual distribution of the temperature on the vessel wall is non-uniform and time-varying, and this feature makes the convective coefficient variable. Methods This paper presents a realistic time-varying model in which h is a function of the temperature distribution at the vessel wall. The finite-element method (FEM was employed in order to model RF hepatic ablation. Two geometrical configurations were investigated. The RF electrode was placed at distances of 1 and 5 mm from a large vessel (10 mm diameter. Results When the ablation procedure takes longer than 1–2 min, the attained coagulation zone obtained with both time-varying h and constant h does not differ significantly. However, for short duration ablation (5–10 s and when the electrode is 1 mm away from the vessel, the use of constant h can lead to errors as high as 20% in the estimation of the coagulation zone. Conclusion For tumor ablation procedures typically lasting at least 5 min, this study shows that modeling the heat sink effect of large vessels by applying constant h as a boundary condition will yield precise results while reducing computational complexity. However, for other thermal therapies with shorter treatment using a time-varying h may be necessary.
Demyk, K.; Meny, C.; Leroux, H.; Depecker, C.; Brubach, J.-B.; Roy, P.; Nayral, C.; Ojo, W.-S.; Delpech, F.
2017-10-01
Context. To model the cold dust emission observed in the diffuse interstellar medium, in dense molecular clouds or in cold clumps that could eventually form new stars, it is mandatory to know the physical and spectroscopic properties of this dust and to understand its emission. Aims: This work is a continuation of previous studies aiming at providing astronomers with spectroscopic data of realistic cosmic dust analogues for the interpretation of observations. The aim of the present work is to extend the range of studied analogues to iron-rich silicate dust analogues. Methods: Ferromagnesium amorphous silicate dust analogues were produced by a sol-gel method with a mean composition close to Mg1-xFexSiO3 with x = 0.1, 0.2, 0.3, 0.4. Part of each sample was annealed at 500 °C for two hours in a reducing atmosphere to modify the oxidation state of iron. We have measured the mass absorption coefficient (MAC) of these eight ferromagnesium amorphous silicate dust analogues in the spectral domain 30-1000 μm for grain temperature in the range 10-300 K and at room temperature in the 5-40 μm range. Results: The MAC of ferromagnesium samples behaves in the same way as the MAC of pure Mg-rich amorphous silicate samples. In the 30-300 K range, the MAC increases with increasing grain temperature whereas in the range 10-30 K, we do not see any change of the MAC. The MAC cannot be described by a single power law in λ- β. The MAC of the samples does not show any clear trend with the iron content. However the annealing process has, on average, an effect on the MAC that we explain by the evolution of the structure of the samples induced by the processing. The MAC of all the samples is much higher than the MAC calculated by dust models. Conclusions: The complex behavior of the MAC of amorphous silicates with wavelength and temperature is observed whatever the exact silicate composition (Mg vs. Fe amount). It is a universal characteristic of amorphous materials, and therefore of
Quirama, M.; Morales, R.
2016-12-01
Light-absorbing carbonaceous aerosol is recognized as a significant short lived climate pollutant that can contribute to direct and indirect radiative forcing. In urban environments, black carbon is an important contributor to the deterioration of local air quality. In this study, we report measurements of equivalent Black Carbon performed during the months of January, February, and March 2016 in the city of Bogotá, Colombia. During this period, a persistent condition of atmospheric stability lead to high concentrations of particulate matter throughout the city. During the month of February, the city was further impacted by a series of small-scale forest fires that took place on hills neighboring the city center. Equivalent Black Carbon (eBC) concentrations were monitored before, during, and after a mayor forest fire episode with a 7-wavelength Aethalometer. The monitoring instruments were located at a traffic impacted site, 18.3 km from the forest fire. To evaluate the contribution of biomass burning to the light-absorbing aerosol particle concentration, spectral analysis of the absorption coefficient of the sampled aerosol particles was performed. When the biomass burning plume directly impacted the monitoring station during the night of February 4, eBC concentrations of up to 40 µg/m3 were observed at nighttime. This concentration was significantly higher than average nighttime concentrations of eBC, observed to be 4 µg/m3 at the site. However, during the period most intensely affected by the biomass burning plume, the angstrom exponent computed between the 450nm and the 970 nm channel, was found to be close to 1. Angstrom exponent close to 1 is an indication that the contribution from traffic generated black carbon is dominant compared to the contribution of biomass burning. The data set collected during this period suggests that despite the significant contribution of the fresh biomass burning plume to the particulate matter concentration in the city, the
U.S. Environmental Protection Agency — In situ analyses of Ag speciation in tissues of cucumber and wheat using synchrotron-based X-ray absorption spectroscopy showing spectral fitting and linear...
Kaya, Necati; Tıraşoğlu, Engin; Apaydın, Gökhan; Aylıkcı, Volkan; Cengiz, Erhan
2007-08-01
The K-shell absorption jump factors and jump ratios were derived from new mass attenuation coefficients measured using an energy dispersive X-ray fluorescence (EDXRF) spectrometer for Tm, Yb elements being Tm 2O 3, Yb 2O 3 compounds and pure Lu, Hf, Ta, W, Re and Os. The measurements, in the region 56-77 keV, were done in a transmission geometry utilizing the K α1 , K α2 , K β1 and K β2 X- rays from different secondary source targets (Yb, Ta, Os, W, Re and Ir, etc.) excited by the 123.6 keV γ-photons from an 57Co annular source and detected by an Ultra-LEGe solid state detector with a resolution of 150 eV at 5.9 keV. Experimental results have been compared with theoretically calculated values. The measured values of Tm, Yb, Lu, Hf, Ta, W, Re and Os are reported here for the first time.
International Nuclear Information System (INIS)
Ungan, F.; Restrepo, R.L.; Mora-Ramos, M.E.; Morales, A.L.; Duque, C.A.
2014-01-01
The effects of hydrostatic pressure, temperature, and electric field on the optical absorption coefficients and refractive index changes associated with intersubband transition in a typical GaAs/Ga 0.7 Al 0.3 As graded quantum well under intense laser field have been investigated theoretically. The electron energy eigenvalues and the corresponding eigenfunctions of the graded quantum well are calculated within the effective mass approximation and envelope wave function approach. The analytical expressions of the optical properties are obtained using the compact density-matrix approach and the iterative method. The numerical results show that the linear and nonlinear optical properties depend strongly on the intense laser field and electric field but weakly on the hydrostatic pressure and temperature. Additionally, it has been found that the electronic and optical properties in a GaAs/Ga 0.7 Al 0.3 As graded quantum well under the intense laser field can be tuned by changing these external inputs. Thus, these results give a new degree of freedom in the devices applications
International Nuclear Information System (INIS)
Kaya, Necati; Tirasoglu, Engin; Apaydin, Goekhan; Aylikci, Volkan; Cengiz, Erhan
2007-01-01
The K-shell absorption jump factors and jump ratios were derived from new mass attenuation coefficients measured using an energy dispersive X-ray fluorescence (EDXRF) spectrometer for Tm, Yb elements being Tm 2 O 3 , Yb 2 O 3 compounds and pure Lu, Hf, Ta, W, Re and Os. The measurements, in the region 56-77 keV, were done in a transmission geometry utilizing the K α1 , K α2 , K β1 and K β2 X- rays from different secondary source targets (Yb, Ta, Os, W, Re and Ir, etc.) excited by the 123.6 keV γ-photons from an 57 Co annular source and detected by an Ultra-LEGe solid state detector with a resolution of 150 eV at 5.9 keV. Experimental results have been compared with theoretically calculated values. The measured values of Tm, Yb, Lu, Hf, Ta, W, Re and Os are reported here for the first time
Energy Technology Data Exchange (ETDEWEB)
Ungan, F., E-mail: fungan@cumhuriyet.edu.tr [Department of Physics, Cumhuriyet University, 58140 Sivas (Turkey); Grupo de Materia Condensade-UdeA, Instituto de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia); Restrepo, R.L. [Grupo de Materia Condensade-UdeA, Instituto de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia); Escuela de Ingeniería de Antioquia AA 7516, Medellín (Colombia); Mora-Ramos, M.E. [Grupo de Materia Condensade-UdeA, Instituto de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia); Facultad de Ciencias, Universidad Autonoma del Estado de Morelos, Ave. Universidad 1001, CP 62209, Cuernavaca, Morelos (Mexico); Morales, A.L.; Duque, C.A. [Grupo de Materia Condensade-UdeA, Instituto de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia)
2014-02-01
The effects of hydrostatic pressure, temperature, and electric field on the optical absorption coefficients and refractive index changes associated with intersubband transition in a typical GaAs/Ga{sub 0.7}Al{sub 0.3}As graded quantum well under intense laser field have been investigated theoretically. The electron energy eigenvalues and the corresponding eigenfunctions of the graded quantum well are calculated within the effective mass approximation and envelope wave function approach. The analytical expressions of the optical properties are obtained using the compact density-matrix approach and the iterative method. The numerical results show that the linear and nonlinear optical properties depend strongly on the intense laser field and electric field but weakly on the hydrostatic pressure and temperature. Additionally, it has been found that the electronic and optical properties in a GaAs/Ga{sub 0.7}Al{sub 0.3}As graded quantum well under the intense laser field can be tuned by changing these external inputs. Thus, these results give a new degree of freedom in the devices applications.
Hoogendam, Jacob P.; Klerkx, Wenche M.; de Kort, Gerard A. P.; Bipat, Shandra; Zweemer, Ronald P.; Sie-Go, Daisy M. D. S.; Verheijen, René H. M.; Mali, Willem P. T. M.; Veldhuis, Wouter B.
2010-01-01
To analyze the influence of different b-value combinations on apparent diffusion coefficient (ADC)-based differentiation of known malignant and benign tissue in cervical cancer patients. A total of 35 patients with stage IB1, IB2, IIA cervical cancer underwent a 3.0T MRI scan prior to radical
Strontium Localization in Bone Tissue Studied by X-Ray Absorption Spectroscopy
DEFF Research Database (Denmark)
Frankær, Christian Grundahl; Raffalt, Anders Christer; Ståhl, Kenny
2014-01-01
Strontium has recently been introduced as a pharmacological agent for the treatment and prevention of osteoporosis. We determined the localization of strontium incorporated into bone matrix from dogs treated with Sr malonate by X-ray absorption spectroscopy. A new approach for analyzing the X...... highly ordered sites, and at least 30 % is located at less ordered sites where only the first solvation shell is resolved, suggesting that strontium is sur- rounded by only oxygen atoms similar to Sr2? in solution. Strontium was furthermore shown to be absorbed in collagen in which it obtains a higher...
Matsuoka, A.; Hooker, S. B.; Bricaud, A.; Gentili, B.; Babin, M.
2012-10-01
A series of papers have suggested that freshwater discharge, including a large amount of dissolved organic matter (DOM), has increased since the middle of the 20th century. In this study, a semi-analytical algorithm for estimating light absorption coefficients of the colored fraction of DOM (CDOM) was developed for Southern Beaufort Sea waters using remote sensing reflectance at six wavelengths in the visible spectral domain corresponding to MODIS ocean color sensor. This algorithm allows to separate colored detrital matter (CDM) into CDOM and non-algal particles (NAP) by determining NAP absorption using an empirical relationship between NAP absorption and particle backscattering coefficients. Evaluation using independent datasets, that were not used for developing the algorithm, showed that CDOM absorption can be estimated accurately to within an uncertainty of 35% and 50% for oceanic and turbid waters, respectively. In situ measurements showed that dissolved organic carbon (DOC) concentrations were tightly correlated with CDOM absorption (r2 = 0.97). By combining the CDOM absorption algorithm together with the DOC versus CDOM relationship, it is now possible to estimate DOC concentrations in the near-surface layer of the Southern Beaufort Sea using satellite ocean color data. DOC concentrations in the surface waters were estimated using MODIS ocean color data, and the estimates showed reasonable values compared to in situ measurements. We propose a routine and near real-time method for deriving DOC concentrations from space, which may open the way to an estimate of DOC budgets for Arctic coastal waters.
Kim, Jin You; Suh, Hie Bum; Kang, Hyun Jung; Shin, Jong Ki; Choo, Ki Seok; Nam, Kyung Jin; Lee, Seok Won; Jung, Young Lae; Bae, Young Tae
2016-05-01
The purpose of this study was to investigate prospectively whether the apparent diffusion coefficients (ADCs) of both breast cancer and normal fibroglandular tissue vary with the menstrual cycle and menopausal status. Institutional review board approval was obtained, and informed consent was obtained from each participant. Fifty-seven women (29 premenopausal, 28 postmenopausal) with newly diagnosed breast cancer underwent diffusion-weighted imaging twice (interval 12-20 days) before surgery. Two radiologists independently measured ADC of breast cancer and normal contralateral breast tissue, and we quantified the differences according to the phases of menstrual cycle and menopausal status. With normal fibroglandular tissue, ADC was significantly lower in postmenopausal than in premenopausal women (P = 0.035). In premenopausal women, ADC did not differ significantly between proliferative and secretory phases in either breast cancer or normal fibroglandular tissue (P = 0.969 and P = 0.519, respectively). In postmenopausal women, no significant differences were found between ADCs measured at different time intervals in either breast cancer or normal fibroglandular tissue (P = 0.948 and P = 0.961, respectively). The within-subject variability of the ADC measurements was quantified using the coefficient of variation (CV) and was small: the mean CVs of tumor ADC were 2.90 % (premenopausal) and 3.43 % (postmenopausal), and those of fibroglandular tissue ADC were 4.37 % (premenopausal) and 2.55 % (postmenopausal). Both intra- and interobserver agreements were excellent for ADC measurements, with intraclass correlation coefficients in the range of 0.834-0.974. In conclusion, the measured ADCs of breast cancer and normal fibroglandular tissue were not affected significantly by menstrual cycle, and the measurements were highly reproducible both within and between observers.
Hu, Hui; Lu, Hong; He, Zhanping; Han, Xiangjun; Chen, Jing; Tu, Rong
2012-07-25
To investigate the effects of mRNA interference on aquaporin-4 expression in swollen tissue of rats with ischemic cerebral edema, and diagnose the significance of diffusion-weighted MRI, we injected 5 μL shRNA- aquaporin-4 (control group) or siRNA- aquaporin-4 solution (1:800) (RNA interference group) into the rat right basal ganglia immediately before occlusion of the middle cerebral artery. At 0.25 hours after occlusion of the middle cerebral artery, diffusion-weighted MRI displayed a high signal; within 2 hours, the relative apparent diffusion coefficient decreased markedly, aquaporin-4 expression increased rapidly, and intracellular edema was obviously aggravated; at 4 and 6 hours, the relative apparent diffusion coefficient slowly returned to control levels, aquaporin-4 expression slightly increased, and angioedema was observed. In the RNA interference group, during 0.25-6 hours after injection of siRNA- aquaporin-4 solution, the relative apparent diffusion coefficient slightly fluctuated and aquaporin-4 expression was upregulated; during 0.5-4 hours, the relative apparent diffusion coefficient was significantly higher, while aquaporin-4 expression was significantly lower when compared with the control group, and intracellular edema was markedly reduced; at 0.25 and 6 hours, the relative apparent diffusion coefficient and aquaporin-4 expression were similar when compared with the control group; obvious angioedema remained at 6 hours. Pearson's correlation test results showed that aquaporin-4 expression was negatively correlated with the apparent diffusion coefficient (r = -0.806, P coefficient. Aquaporin-4 gene interference can effectively inhibit the upregulation of aquaporin-4 expression during the stage of intracellular edema with time-effectiveness. Moreover, diffusion-weighted MRI can accurately detect intracellular edema.
Shiba, Kenji; Nagato, Tomohiro; Tsuji, Toshio; Koshiji, Kohji
2008-07-01
This paper reports on the electromagnetic influences on the analysis of biological tissue surrounding a prototype energy transmission system for a wireless capsule endoscope. Specific absorption rate (SAR) and current density were analyzed by electromagnetic simulator in a model consisting of primary coil and a human trunk including the skin, fat, muscle, small intestine, backbone, and blood. First, electric and magnetic strength in the same conditions as the analytical model were measured and compared to the analytical values to confirm the validity of the analysis. Then, SAR and current density as a function of frequency and output power were analyzed. The validity of the analysis was confirmed by comparing the analytical values with the measured ones. The SAR was below the basic restrictions of the International Commission on Nonionizing Radiation Protection (ICNIRP). At the same time, the results for current density show that the influence on biological tissue was lowest in the 300-400 kHz range, indicating that it was possible to transmit energy safely up to 160 mW. In addition, we confirmed that the current density has decreased by reducing the primary coil's current.
DEFF Research Database (Denmark)
Bjerre-Jepsen, K; Faris, I; Henriksen, O
1982-01-01
Knowledge of the tissue to blood partition coefficient (lambda) is essential for calculation of the perfusion coefficient in a single tissue based on measurements of the washout of locally injected isotopes. No measurements of lambda for Xenon in subcutaneous tissue in the leg have been done...... in patients with occlusive arterial disease. In 12 patients with occlusive arterial disease in the legs lambda for Xenon was determined in subcutaneous tissue in the calf region and foot as the ratio between the washout rate constant of 131I-Antipyrine and 133Xe. A mixture of the two indicators was injected....... Mean value was 3.7 ml X g-1 (range: 1 X 7-10 X 7) in the calf and 2 X 7 ml X g-1 (range: 1 X 2-4 X 9) in the foot. It is concluded that lambda measurements are necessary for determination of subcutaneous blood flow from 133Xe washout curves in these patients. Determination of lambda is especially...
Energy Technology Data Exchange (ETDEWEB)
Yesilgul, U., E-mail: uyesilgul@cumhuriyet.edu.tr [Cumhuriyet University, Physics Department, 58140 Sivas (Turkey); Ungan, F. [Cumhuriyet University, Physics Department, 58140 Sivas (Turkey); Sakiroglu, S. [Dokuz Eylül University, Physics Department, 35160 Buca, İzmir (Turkey); Mora-Ramos, M.E. [Facultad de Ciencias Universidad Autonoma del Estado de Morelos, Ave. Universidad 1001, C.P. 62209 Cuernavaca, Morelos (Mexico); Duque, C.A. [Grupo de Materia Condensada-UdeA, Instituto de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia); Kasapoglu, E.; Sarı, H. [Cumhuriyet University, Physics Department, 58140 Sivas (Turkey); Sökmen, I. [Dokuz Eylül University, Physics Department, 35160 Buca, İzmir (Turkey)
2014-01-15
The effects of the intense high-frequency laser field on the optical absorption coefficients and the refractive index changes in a GaAs/GaAlAs parabolic quantum well under the applied electric field have been investigated theoretically. The electron energy levels and the envelope wave functions of the parabolic quantum well are calculated within the effective mass approximation. Analytical expressions for optical properties are obtained using the compact density-matrix approach. The numerical results show that the intense high-frequency laser field has a large effect on the optical characteristics of these structures. Also we can observe that the refractive index and absorption coefficient changes are very sensitive to the electric field in large dimension wells. Thus, this result gives a new degree of freedom in the optoelectronic device applications. -- Highlights: • ILF has a large effect on the optical properties of parabolic quantum wells. • The total absorption coefficients increase as the ILF increases. • The RICs increase as the ILF increases.
Energy Technology Data Exchange (ETDEWEB)
Baghramyan, H.M. [Department of Solid State Physics, Yerevan State University, Al. Manookian 1, 0025 Yerevan (Armenia); Barseghyan, M.G., E-mail: mbarsegh@ysu.am [Department of Solid State Physics, Yerevan State University, Al. Manookian 1, 0025 Yerevan (Armenia); Kirakosyan, A.A. [Department of Solid State Physics, Yerevan State University, Al. Manookian 1, 0025 Yerevan (Armenia); Restrepo, R.L. [Escuela de Ingenieria de Antioquia, AA 7516 Medellin (Colombia); Duque, C.A. [Instituto de Fisica, Universidad de Antioquia, AA 1226 Medellin (Colombia)
2013-02-15
The linear and nonlinear intra-band optical absorption coefficients in GaAs/Ga{sub 1-x}Al{sub x}As two-dimensional concentric double quantum rings are investigated. Taking into account the combined effects of hydrostatic pressure and aluminum concentration the energies of the ground (n=1,l=0) and the first excited state (n=2,l=1) have been found using the effective mass approximation and the transfer matrix formalism. The energies of these states and the corresponding threshold energy of the intra-band optical transitions are examined as a function of hydrostatic pressure and aluminum concentration for different sizes of the structure. We also investigated the dependencies of the linear, nonlinear, and total optical absorption coefficients as functions of the incident photon energy for different values of hydrostatic pressure, aluminum concentration, sizes of the structure, and incident optical intensity. Its is found that the effects of the hydrostatic pressure and the aluminum concentration lead to a shifting of the resonant peaks of the intra-band optical spectrum. - Highlights: Black-Right-Pointing-Pointer Linear and nonlinear intra-band absorption in quantum rings. Black-Right-Pointing-Pointer Threshold energy strongly depends on the hydrostatic pressure. Black-Right-Pointing-Pointer Threshold energy strongly depends on the stoichiometry and sizes of structure. Black-Right-Pointing-Pointer Optical absorption is affected by the incident optical intensity.
Matsuoka, A.; Hooker, S. B.; Bricaud, A.; Gentili, B.; Babin, M.
2013-02-01
A series of papers have suggested that freshwater discharge, including a large amount of dissolved organic matter (DOM), has increased since the middle of the 20th century. In this study, a semi-analytical algorithm for estimating light absorption coefficients of the colored fraction of DOM (CDOM) was developed for southern Beaufort Sea waters using remote sensing reflectance at six wavelengths in the visible spectral domain corresponding to MODIS ocean color sensor. This algorithm allows the separation of colored detrital matter (CDM) into CDOM and non-algal particles (NAP) through the determination of NAP absorption using an empirical relationship between NAP absorption and particle backscattering coefficients. Evaluation using independent datasets, which were not used for developing the algorithm, showed that CDOM absorption can be estimated accurately to within an uncertainty of 35% and 50% for oceanic and coastal waters, respectively. A previous paper (Matsuoka et al., 2012) showed that dissolved organic carbon (DOC) concentrations were tightly correlated with CDOM absorption in our study area (r2 = 0.97). By combining the CDOM absorption algorithm together with the DOC versus CDOM relationship, it is now possible to estimate DOC concentrations in the near-surface layer of the southern Beaufort Sea using satellite ocean color data. DOC concentrations in the surface waters were estimated using MODIS ocean color data, and the estimates showed reasonable values compared to in situ measurements. We propose a routine and near real-time method for deriving DOC concentrations from space, which may open the way to an estimate of DOC budgets for Arctic coastal waters.
Directory of Open Access Journals (Sweden)
A. Matsuoka
2013-02-01
Full Text Available A series of papers have suggested that freshwater discharge, including a large amount of dissolved organic matter (DOM, has increased since the middle of the 20th century. In this study, a semi-analytical algorithm for estimating light absorption coefficients of the colored fraction of DOM (CDOM was developed for southern Beaufort Sea waters using remote sensing reflectance at six wavelengths in the visible spectral domain corresponding to MODIS ocean color sensor. This algorithm allows the separation of colored detrital matter (CDM into CDOM and non-algal particles (NAP through the determination of NAP absorption using an empirical relationship between NAP absorption and particle backscattering coefficients. Evaluation using independent datasets, which were not used for developing the algorithm, showed that CDOM absorption can be estimated accurately to within an uncertainty of 35% and 50% for oceanic and coastal waters, respectively. A previous paper (Matsuoka et al., 2012 showed that dissolved organic carbon (DOC concentrations were tightly correlated with CDOM absorption in our study area (r^{2} = 0.97. By combining the CDOM absorption algorithm together with the DOC versus CDOM relationship, it is now possible to estimate DOC concentrations in the near-surface layer of the southern Beaufort Sea using satellite ocean color data. DOC concentrations in the surface waters were estimated using MODIS ocean color data, and the estimates showed reasonable values compared to in situ measurements. We propose a routine and near real-time method for deriving DOC concentrations from space, which may open the way to an estimate of DOC budgets for Arctic coastal waters.
Haritova, A.M.; Fink-Gremmels, J.
2010-01-01
Tissue residues arise from the exposure of animals to undesirable substances in animal feed materials and drinking water and to the therapeutic or zootechnical use of veterinary medicinal products. In the framework of this study, an advanced toxicokinetic model was developed to predict the
Chernyshov, A. K.; Mikheyev, P. A.; Lunev, N. N.; Azyazov, V. N.
2018-04-01
Optically pumped all-rare-gas laser (OPRGL) with unique properties were recently proposed with a possibility to obtain the laser power on the order of hundreds of Watts from a cubic centimeter. To provide high laser efficiency, the pumping radiation has to match the absorption spectrum of the rare gas metastables. To meet this condition a reliable diagnostics of the key parameters of the active medium is required and knowledge of the broadening and shift coefficients for corresponding transitions of rare gases is necessary. In this paper, the diode-laser absorption spectroscopy was employed to determine the pressure shift coefficient for 811.5 nm Ar line. The value of obtained coefficient in pure argon reduced to 300 K is -(2.1 ± 0.1) × 10-10 s-1cm3. In the course of the study the pressure broadening coefficient was also evaluated and found to be (2.4 ± 0.5) × 10-10 s-1cm3.
Liebert, Adam; Wabnitz, Heidrun; Elster, Clemens
2012-05-01
Time-resolved near-infrared spectroscopy allows for depth-selective determination of absorption changes in the adult human head that facilitates separation between cerebral and extra-cerebral responses to brain activation. The aim of the present work is to analyze which combinations of moments of measured distributions of times of flight (DTOF) of photons and source-detector separations are optimal for the reconstruction of absorption changes in a two-layered tissue model corresponding to extra- and intra-cerebral compartments. To this end we calculated the standard deviations of the derived absorption changes in both layers by considering photon noise and a linear relation between the absorption changes and the DTOF moments. The results show that the standard deviation of the absorption change in the deeper (superficial) layer increases (decreases) with the thickness of the superficial layer. It is confirmed that for the deeper layer the use of higher moments, in particular the variance of the DTOF, leads to an improvement. For example, when measurements at four different source-detector separations between 8 and 35 mm are available and a realistic thickness of the upper layer of 12 mm is assumed, the inclusion of the change in mean time of flight, in addition to the change in attenuation, leads to a reduction of the standard deviation of the absorption change in the deeper tissue layer by a factor of 2.5. A reduction by another 4% can be achieved by additionally including the change in variance.
Flores, Rolando A; Tamplin, Mark L; Marmer, Benne S; Phillips, John G; Cooke, Peter H
2006-06-01
Risk studies have identified cross-contamination during beef fabrication as a knowledge gap, particularly as to how and at what levels Escherichia coli O157:H7 transfers among meat and cutting board (or equipment) surfaces. The objectives of this study were to determine and model transfer coefficients (TCs) between E. coli O157:H7 on beef tissue and high-density polyethylene (HDPE) cutting board surfaces. Four different transfer scenarios were evaluated: (i) HDPE board to agar, (ii) beef tissue to agar, (iii) HDPE board to beef tissue to agar, and (iv) beef tissue to HDPE board to agar. Also, the following factors were studied for each transfer scenario: two HDPE surface roughness levels (rough and smooth), two beef tissues (fat and fascia), and two conditions of the initial beef tissue inoculation with E. coli O157:H7 (wet and dry surfaces), for a total of 24 treatments. The TCs were calculated as a function of the plated inoculum and of the cells recovered from the first contact. When the treatments were compared, all of the variables evaluated interacted significantly in determining the TC. An overall TC-per-treatment model did not adequately represent the reduction of the cells on the original surface after each contact and the interaction of the factors studied. However, an exponential model was developed that explained the experimental data for all treatments and represented the recontamination of the surfaces with E. coli O157:H7. The parameters for the exponential model for cross-contamination with E. coli O157:H7 between beef tissue and HDPE surfaces were determined, allowing for the use of the resulting model in quantitative microbial risk assessment.
Energy Technology Data Exchange (ETDEWEB)
Petrovic, M; Markovic, V; Velickovic, Lj [Boris Kidric Institute of nuclear sciences, Vinca, Belgrade (Yugoslavia)
1963-07-01
Full text: This activity is a logical continuation of the experiment at the RA reactor during 1962 which was based on compensating the effect by means of control rod. Since results are given with significant errors, new method for measuring the absorption cross sections via reactor period. Experiment was done at the RB reactor which was particularly prepared for this type of experiments. Reactor power was from 50 mW to 2 W. Absorption cross sections were measured for two types of material: domestic graphite No.3 and French graphite 'Pachiney', and two types of aluminium. Total errors in applying this method are {+-} 5%, where the source of major part of error comes from uncertainty of the standard absorption power (previous method gave {+-} 10 do 55% ). Comparison of French graphite absorption cross section obtained via reactor period and via control rod showed approximate agreement with discrepancy of 5.4% which is considered within the precision of this method. Considering the accuracy of measurement results and reactor economy it is concluded that measuring absorption cross sections of samples via period of RB reactor is more favourable than measurements by control rod at the RA reactor. Pun tekst: Ovaj rad predstavlja logican nastavak eksperimenta na reaktoru RA u toku 1962. godine, koji je bazirao na kompenzaciji efekta pomocu kontrolne sipke. Kako su rezultati dati sa velikim greskama, to se prislo novom nacinu merenja apsorpsionih preseka preko periode reaktora. Eksperiment je radjen na reaktoru RB koji je specijalno pripremljen za ovu vrstu eksperimenta. Snaga reaktora se kretala od 50 mW do 2 W. Preko periode reaktora RB odredjeni su apsorpcioni preseci za dve vrste materijala i to: domaci grafit No.3 i francuski 'Pachiney', i dve vrste aluminijuma. Ukupne greske pri ovom nacimu merenja iznose oko {+-} 5%, gde glavni deo greske nosi neodredjenost apsorpcione moci standarda (ranija metoda je dala {+-} 10 do 55% ). Poredjenjem vrednosti apsorpcionih preseka
International Nuclear Information System (INIS)
Resano, M.; Briceno, J.; Aramendia, M.; Belarra, M.A.
2007-01-01
In this work, the potential of graphite furnace atomic absorption spectrometry for the direct determination of B in plant tissues has been investigated. Three certified reference materials (NIST SRM 1570a spinach leaves, NIST SRM 1573a tomato leaves and BCR CRM 679 white cabbage) were selected for this study, the goal always being to develop a fast procedure that could be robust enough to provide a satisfactory performance for all of them, without any modifications in the conditions applied. The use of a suitable chemical modifier was found to be essential for obtaining a reproducible and sufficiently sensitive signal for boron solutions. In this regard, the performance of the combination of citric acid plus W (added as a permanent modifier) was noteworthy, resulting in well-defined signal profiles, a remarkable analyte stabilization during the pyrolysis step (up to 2100 deg. C) and minimal memory effects. This mixture of modifiers provided a good performance for the direct analysis of solid samples as well, but only if a suitable temperature program, favoring the interaction between the analyte and the modifiers, was used. Thus, such a temperature program, with two pyrolysis steps and the addition of NH 4 NO 3 in order to carry out the in situ sample microdigestion, was optimized. Under these conditions, the peak areas obtained for both solid samples and aqueous standards were comparable. Finally, the analysis of the samples was carried out. In all cases, a good agreement with the certified values was obtained, while R.S.D. values ranged between 6 and 10%. It can be concluded that the method proposed shows significant advantages for the determination of this complicated element in solid samples such as the use of aqueous standards for calibration, a high sample throughput (20 min per sample), a suitable limit of detection (0.3 μg g -1 ) and reduced risk of analyte losses and contamination
International Nuclear Information System (INIS)
Li Jingsong; Durry, Georges; Cousin, Julien; Joly, Lilian; Parvitte, Bertrand; Zeninari, Virginie
2010-01-01
The self-broadening coefficients of acetylene at room temperature have been measured for 10 lines in the P branch of the ν 1 +ν 3 (Σ u + )-0(Σ g + ) bands of 12 C 2 H 2 and 13 C 12 CH 2 near 1.533 μm, using a high resolution tunable diode laser spectrometer developed for the Martian space mission PHOBOS-Grunt. The collisional widths are obtained by fitting each recorded line with the Voigt profile as well as the Rautian profile accounting for the collisional Dicke narrowing effect. The standard Voigt model provides slightly smaller broadening coefficients than the Rautian model. Our data are thoroughly compared to the main atmospheric molecule database HITRAN and previous values in various bands of acetylene. Moreover, it is worth noting that a large number of new transitions not listed in the latest HITRAN08 were measured and identified for the first time.
Energy Technology Data Exchange (ETDEWEB)
Baghramyan, H.M.; Barseghyan, M.G.; Kirakosyan, A.A. [Department of Solid State Physics, Yerevan State University, Al. Manookian 1, 0025 Yerevan (Armenia); Restrepo, R.L. [Física Teórica y Aplicada, Escuela de Ingeniería de Antioquia, AA 7516, Medellín (Colombia); Grupo de Materia Condensada-UdeA, Instituto de Física, Facultadde Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21,Medellín (Colombia); Mora-Ramos, M.E. [Grupo de Materia Condensada-UdeA, Instituto de Física, Facultadde Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21,Medellín (Colombia); Facultad de Ciencias, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, CP 62209, Cuernavaca, Morelos (Mexico); Duque, C.A., E-mail: cduque@fisica.udea.edu.co [Grupo de Materia Condensada-UdeA, Instituto de Física, Facultadde Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21,Medellín (Colombia)
2014-01-15
The linear and nonlinear optical absorption associated with the transition between 1s and 2s states corresponding to the electron-donor-impurity complex in GaAs/Ga{sub 1−x}Al{sub x}As three-dimensional concentric double quantum rings are investigated. Taking into account the combined effects of hydrostatic pressure and the variation of the aluminum concentration, the energies of the ground and first excited s-like states of a donor impurity in such a system have been calculated using the effective mass approximation and a variational method. The energies of these states and the corresponding threshold energy of the optical transitions are examined as functions of hydrostatic pressure, aluminum concentration, radial impurity position, as well as the geometrical dimensions of the structure. The dependencies of the linear, nonlinear and total optical absorption coefficients as functions of the incident photon energy are investigated for different values of those mentioned parameters. It is found that the influences mentioned above lead to either redshifts or blueshifts of the resonant peaks of the optical absorption spectrum. It is particularly discussed the unusual property exhibited by the third-order nonlinear of becoming positive for photon energies below the resonant transition one. It is shown that this phenomenon is associated with the particular features of the system under study, which determine the values of the electric dipole moment matrix elements. -- Highlights: • Intra-band optical absorption associated to impurity states in double quantum rings. • Combined effects of hydrostatic pressure and aluminum concentration are studied. • The influences mentioned above lead to shifts of resonant peaks. • It is discussed an unusual property exhibited by the third-order nonlinear absorption.
International Nuclear Information System (INIS)
Baghramyan, H.M.; Barseghyan, M.G.; Kirakosyan, A.A.; Restrepo, R.L.; Mora-Ramos, M.E.; Duque, C.A.
2014-01-01
The linear and nonlinear optical absorption associated with the transition between 1s and 2s states corresponding to the electron-donor-impurity complex in GaAs/Ga 1−x Al x As three-dimensional concentric double quantum rings are investigated. Taking into account the combined effects of hydrostatic pressure and the variation of the aluminum concentration, the energies of the ground and first excited s-like states of a donor impurity in such a system have been calculated using the effective mass approximation and a variational method. The energies of these states and the corresponding threshold energy of the optical transitions are examined as functions of hydrostatic pressure, aluminum concentration, radial impurity position, as well as the geometrical dimensions of the structure. The dependencies of the linear, nonlinear and total optical absorption coefficients as functions of the incident photon energy are investigated for different values of those mentioned parameters. It is found that the influences mentioned above lead to either redshifts or blueshifts of the resonant peaks of the optical absorption spectrum. It is particularly discussed the unusual property exhibited by the third-order nonlinear of becoming positive for photon energies below the resonant transition one. It is shown that this phenomenon is associated with the particular features of the system under study, which determine the values of the electric dipole moment matrix elements. -- Highlights: • Intra-band optical absorption associated to impurity states in double quantum rings. • Combined effects of hydrostatic pressure and aluminum concentration are studied. • The influences mentioned above lead to shifts of resonant peaks. • It is discussed an unusual property exhibited by the third-order nonlinear absorption
Energy Technology Data Exchange (ETDEWEB)
Christ, A [Foundation for Research on Information Technologies in Society (IT' IS), Zeughausstr 43, 8004 Zurich (Switzerland); Samaras, T [Radiocommunications Laboratory, Aristotle University of Thessaloniki, 541 24 Thessaloniki (Greece); Klingenboeck, A [Foundation for Research on Information Technologies in Society (IT' IS), Zeughausstr 43, 8004 Zurich (Switzerland); Kuster, N [Foundation for Research on Information Technologies in Society (IT' IS), Zeughausstr 43, 8004 Zurich (Switzerland)
2006-10-07
Currently, standards for the compliance testing of wireless devices are being extended to cover a wider frequency band and different usage patterns of mobile phones as well as of novel body-worn and handheld devices. As a consequence, not only the head but also strongly varying tissue distributions of the body are exposed to electromagnetic radiation. Several authors have reported changes in the SAR absorption of body tissue due to the presence of a low permittivity fat layer. This paper identifies two different effects which can lead to increased SAR in layered tissue in comparison to the SAR assessed using homogeneous tissue simulating liquid: (1) for larger distances between the tissue and the antenna, standing wave effects occur depending on the frequency and fat layer thickness. (2) In the very close near-field (distances approximately {lambda}/40), reactive E-field components lead to high local absorption in the skin. The latter effect occurs at lower frequencies and depends on the antenna type. Modification of the parameters of the homogeneous liquids cannot compensate for these effects. However, a conservative exposure estimate can be obtained by applying a multiplication factor between 1 and 3 to the values assessed using current experimental dosimetric techniques.
Adubeiro, Nuno; Nogueira, Maria Luísa; Nunes, Rita G; Ferreira, Hugo Alexandre; Ribeiro, Eduardo; La Fuente, José Maria Ferreira
Determining optimal b-value pair for differentiation between normal and prostate cancer (PCa) tissues. Forty-three patients with diagnosis or PCa symptoms were included. Apparent diffusion coefficient (ADC) was estimated using minimum and maximum b-values of 0, 50, 100, 150, 200, 500s/mm2 and 500, 800, 1100, 1400, 1700 and 2000s/mm2, respectively. Diagnostic performances were evaluated when Area-under-the-curve (AUC)>95%. 15 of the 35 b-values pair surpassed this AUC threshold. The pair (50, 2000s/mm2) provided the highest AUC (96%) with ADC cutoff 0.89×10- 3 mm 2 /s, sensitivity 95.5%, specificity 93.2% and accuracy 94.4%. The best b-value pair was b=50, 2000s/mm2. Copyright © 2017 Elsevier Inc. All rights reserved.
Energy Technology Data Exchange (ETDEWEB)
Dakhlaoui, Hassen [Department of Physics, College of Science for Girls, University of Dammam (UOD), Saudi Arabia and Department of Physics, Faculty of Sciences of Bizerte, University of Carthage (Tunisia)
2015-04-07
In the present paper, the linear and nonlinear optical absorption coefficients and refractive index changes between the ground and the first excited states in double GaN/Al{sub x}Ga{sub (1−x)}N quantum wells are studied theoretically. The electronic energy levels and their corresponding wave functions are obtained by solving Schrödinger-Poisson equations self-consistently within the effective mass approximation. The obtained results show that the optical absorption coefficients and refractive index changes can be red- and blue-shifted through varying the left quantum well width and the aluminum concentration x{sub b2} of the central barrier, respectively. These structural parameters are found to present optimum values for carrying out the transition of 0.8 eV (1.55 μm). Furthermore, we show that the desired transition can also be achieved by replacing the GaN in the left quantum well with Al{sub y}Ga{sub (1−y)}N and by varying the aluminum concentration y{sub Al}. The obtained results give a new degree of freedom in optoelectronic device applications such as optical fiber telecommunications operating at (1.55 μm)
Liu, Xiuxiu; Tang, Minghai; Liu, Taohong; Wang, Chunyan; Tang, Qiaoxin; Xiao, Yaxin; Yang, Ruixin; Chao, Ruobing
2017-12-27
1. Mesaconine, an ingredient from Aconitum carmichaelii Debx., has been proven to have cardiac effect. For further development and better pharmacological elucidation, the in vivo process and intestinal absorptive behavior of mesaconine should be investigated comprehensively. 2. An ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for the quantitation of mesaconine in rat plasma, tissue homogenates, urine and feces to investigate the in vivo pharmacokinetic profiles, tissue distribution and excretion. The intestinal absorptive behavior of mesaconine was investigated using in vitro everted rat gut sac model. 3. Mesaconine was well distributed in tissues and a mass of unchanged form was detected in feces. It was difficultly absorbed into blood circulatory system after oral administration. The insufficient oral bioavailability of mesaconine may be mainly attributed to its low intestinal permeability due to a lack of lipophilicity. The absorption of mesaconine in rat's intestine is a first-order process with the passive diffusion mechanism.
Zhu, Wen-Zhuo; Zhang, Hong-Hai; Zhang, Jing; Yang, Gui-Peng
2018-04-01
The absorption coefficient and fluorescent components of chromophoric dissolved organic matter (CDOM) in the Bohai Sea (BS), Yellow Sea (YS), and East China Sea (ECS) in spring and autumn were analyzed in this study. Excitation-emission matrices (EEMs) combined with parallel factor analysis (PARAFAC) identified three components, namely, humic-like C1, tyrosine-like C2 and tryptophan-like C3. The seasonal variations in the vertical patterns of the CDOM absorption coefficient (aCDOM(355)) and fluorescent components were influenced by the seasonal water mass except for the terrestrial input. The relationship between aCDOM(355) and dissolved organic matter (DOC) was attributed to their own mixing behavior. The correlation of the fluorescent components with DOC was disturbed by other non-conservative processes during the export of CDOM to the open ocean. The different chemical compositions and origins of DOC and CDOM led to variability in carbon-specific CDOM absorption (a*CDOM(355)) and fluorescent component ratios (ICn/IC1). The relationship between a*CDOM(355) and aCDOM(355) demonstrated that dissolved organic matter (DOM) in the BS, but not in the ECS, highly contributed non-absorbing DOC to the total DOC concentration. The photodegradation of dominant terrestrially derived CDOM in the ECS contributed to the positive relationship between a*CDOM(355) and ICn/IC1. By contrast, the abundant autochthonous CDOM in the YS was negatively correlated with ICn/IC1 in autumn. Our established box models showed that water exchange is a potentially important source of the aromatic components in the BS, YS, and ECS. Hence, the seasonal variations in water exchange might contribute to the variability of CDOM chemical composition in the BS, YS, and ECS, and significantly influence the structure and function of their ecosystems.
Directory of Open Access Journals (Sweden)
Saad Abdulrahman Hussain
2013-06-01
Full Text Available Aim: To evaluate the effect of long-term use of silibinin, epigallocatechin (ECGC, quercetin and rutin on the absorption and tissue distribution of metformin and atenolol. Materials and Methods: Thirty male rats were used, allocated into 5 groups and treated as follow: 1st group treated with olive oil and served as control; the other 4 groups were treated with either silibinin, EPGC, quercetin or rutin, administered orally as oily solutions for 30 days. At day 30, a 300mg/kg metformin and 50mg/kg atenolol were administered orally; 3.0 hrs later, the animals were sacrificed and blood samples, tissues of brain, kidney and liver were obtained for evaluation of the drugs level. Results: The polyphenols increased both serum and tissue levels of metformin compared with controls. This effect was relatively varied according to the structural differences among flavonoids. Conclusion: Long-term use of supraphysiological doses of flavonoids increase absorption of Zn, Cu and Fe and their tissue availability in brain, kidney and liver; this effect seems to be different with variations in structural features. [J Intercult Ethnopharmacol 2013; 2(3.000: 147-154
Directory of Open Access Journals (Sweden)
NU Rahman
2011-05-01
Full Text Available Background and the purpose of the study: Partition coefficients (log D and log P and molecular surface area (PSA are potential predictors of the intestinal permeability of drugs. The aim of this investigation was to evaluate and compare these intestinal permeability indicators. Methods: Aqueous solubility data were obtained from literature or calculated using ACD/Labs and ALOGPS. Permeability data were predicted based on log P, log D at pH 6.0 (log D6.0, and PSA. Results: Metoprolol's log P, log D6.0 and a PSA of <65 Å correctly predicted 55.9%, 50.8% and 54.2% of permeability classes, respectively. Labetalol's log P, log D6.0, and PSA correctly predicted 54.2%, 64.4% and 61% of permeability classes, respectively. Log D6.0 correlated well (81% with Caco-2 permeability (Papp. Of the list of national essential medicines, 135 orally administered drugs were classified into biopharmaceutical classification system (BCS. Of these, 57 (42.2%, 28 (20.7%, 44 (32.6%, and 6 (4.4% were class I, II, III and IV respectively. Conclusion: Log D6.0 showed better prediction capability than log P. Metoprolol as permeability internal standard was more conservative than labetalol.
DEFF Research Database (Denmark)
Clausen, Trine Schnedler; Kaastrup, Peter; Stallknecht, Bente
2009-01-01
blood flow (ATBF) and absorption of the rapid-acting insulin analog insulin aspart over a period of 4 days. METHODS: Teflon insulin catheters (Medtronic, Minneapolis, MN) were inserted into the abdominal SAT of 10 healthy men without diabetes (mean +/- SEM age, 23.0 +/- 1.1 years; body mass index, 22...... +/- 3 min on day 0 to 45 +/- 4 min on day 4 (P = 0.019). Neither peak plasma concentration nor area under the curve of insulin aspart changed significantly. CONCLUSIONS: Insertion of a Teflon insulin catheter into the SAT results in increased ATBF and faster absorption of insulin aspart in a period of 4...
Directory of Open Access Journals (Sweden)
Chen Rongzhen
2017-01-01
Full Text Available We demonstrate that the band-gap energies Eg of CuSb(Se,Te2 and CuBi(S,Se2 can be optimized for high energy conversion in very thin photovoltaic devices, and that the alloys then exhibit excellent optical properties, especially for tellurium rich CuSb(Se1−xTex2. This is explained by multi-valley band structure with flat energy dispersions, mainly due to the localized character of the Sb/Bi p-like conduction band states. Still the effective electron mass is reasonable small: mc ≈ 0.25m0 for CuSbTe2. The absorption coefficient α(ω for CuSb(Se1−xTex2 is at ħω = Eg + 1 eV as much as 5–7 times larger than α(ω for traditional thin-film absorber materials. Auger recombination does limit the efficiency if the carrier concentration becomes too high, and this effect needs to be suppressed. However with high absorptivity, the alloys can be utilized for extremely thin inorganic solar cells with the maximum efficiency ηmax ≈ 25% even for film thicknesses d ≈ 50 − 150 nm, and the efficiency increases to ∼30% if the Auger effect is diminished.
Chen, Rongzhen; Persson, Clas
2017-06-01
We demonstrate that the band-gap energies Eg of CuSb(Se,Te)2 and CuBi(S,Se)2 can be optimized for high energy conversion in very thin photovoltaic devices, and that the alloys then exhibit excellent optical properties, especially for tellurium rich CuSb(Se1-xTex)2. This is explained by multi-valley band structure with flat energy dispersions, mainly due to the localized character of the Sb/Bi p-like conduction band states. Still the effective electron mass is reasonable small: mc ≈ 0.25m0 for CuSbTe2. The absorption coefficient α(ω) for CuSb(Se1-xTex)2 is at ħω = Eg + 1 eV as much as 5-7 times larger than α(ω) for traditional thin-film absorber materials. Auger recombination does limit the efficiency if the carrier concentration becomes too high, and this effect needs to be suppressed. However with high absorptivity, the alloys can be utilized for extremely thin inorganic solar cells with the maximum efficiency ηmax ≈ 25% even for film thicknesses d ≈ 50 - 150 nm, and the efficiency increases to ˜30% if the Auger effect is diminished.
Song, Y; Yoon, Y C; Chong, Y; Seo, S W; Choi, Y-L; Sohn, I; Kim, M-J
2017-08-01
To compare the abilities of conventional magnetic resonance imaging (MRI) and apparent diffusion coefficient (ADC) in differentiating between benign and malignant soft-tissue tumours (STT). A total of 123 patients with STT who underwent 3 T MRI, including diffusion-weighted imaging (DWI), were retrospectively analysed using variate conventional MRI parameters, ADC mean and ADC min . For the all-STT group, the correlation between the malignant STT conventional MRI parameters, except deep compartment involvement, compared to those of benign STT were statistically significant with univariate analysis. Maximum diameter of the tumour (p=0.001; odds ratio [OR], 8.97) and ADC mean (p=0.020; OR, 4.30) were independent factors with multivariate analysis. For the non-myxoid non-haemosiderin STT group, signal heterogeneity on axial T1-weighted imaging (T1WI; p=0.017), ADC mean , and ADC min (p=0.001, p=0.001), showed significant differences with univariate analysis between malignancy and benignity. Signal heterogeneity in axial T1WI (p=0.025; OR, 12.64) and ADC mean (p=0.004; OR, 33.15) were independent factors with multivariate analysis. ADC values as well as conventional MRI parameters were useful in differentiating between benign and malignant STT. The ADC mean was the most powerful diagnostic parameter in non-myxoid non-haemosiderin STT. Copyright © 2017 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.
Sapozhnikova, Veronika V.; Kutis, Irina S.; Kutis, Sergey D.; Kuranov, Roman V.; Gelikonov, Grigory V.; Shabanov, Dmitry V.; Kamensky, Vladislav A.
2004-07-01
First experimental results on OCT imaging of internal structure of plant tissues and in situ OCT monitoring of plant tissue regeneration at different water supply are reported. Experiments for evaluating OCT capabilities were performed on Tradescantia. The investigation of seeds swelling was performed on wheat seeds (Triticum L.), barley seeds (Hordeum L.), long-fibred flax seeds (Linum usitatissimum L.) and cucumber seeds (Cucumis sativus L.). These OCT images correlate with standard microscopy data from the same tissue regions. Seeds were exposed to a low-intensity physical factor-the pulsed gradient magnetic field (GMF) with pulse duration 0.1 s and maximum amplitude 5 mT (4 successive pulses during 0.4 s). OCT and OCM enable effective monitoring of fast reactions in plants and seeds at different water supply.
Zhan, Yuefu; Liang, Xianwen; Han, Xiangjun; Chen, Jianqiang; Zhang, Shufang; Tan, Shun; Li, Qun; Wang, Xiong; Liu, Fan
2017-02-28
To explore the correlation between the apparent diffusion coefficient (ADC) and mRNA expression of tissue inhibitor of metalloproteinase-1 (TIMP-1) in different stages of liver fibrosis in rats. Methods: A model of liver fibrosis in rats was established by intraperitoneal injection of high-fat diet combined with porcine serum. After drug administration for 4 weeks, 48 rats served as a model group and 12 rats served as a control group, then they underwent diffusion weighted imaging (DWI) scanning. The value of ADC was calculated at b value=800 s/mm2. The rats were sacrificed and carried out pathologic examination after DWI scanning immediately. The mRNA expression of TIMP-1 was detected by real time-polymerase chain reaction (RT-PCR). The rats of hepatic fibrosis were also divided into a S0 group (n=4), a S1 group (n=11), a S2 group (n=12), a S3 group (n=10), and a S4 group (n=9) according to their pathological stage. The value of ADC and the expression of TIMP-1 mRNA among the different stage groups of liver fibrosis were compared, and the correlation between ADC and the TIMP-1 mRNA were analyzed. Results: The ADC value and the TIMP-1 mRNA expression were significantly different between the control group and the liver fibrosis group (F=46.54 and 53.87, P0.05). For the comparison of TIMP-1 mRNA, there was no significant difference between the S1 group and the S2 group, the S3 group and the S4 group (both P>0.05). There were significant differences among the rest of the groups (all Pcorrelation analysis showed that there was a negative correlation between the ADC value and the TIMP-1 mRNA expression (r=-0.76, Pcorrelation between them.
DEFF Research Database (Denmark)
Davidsen, Jesper; Jørgensen, K.; Andresen, Thomas Lars
2003-01-01
Polymer-coated liposomes can act as versatile drug-delivery systems due to long vascular circulation time and passive targeting by leaky blood vessels in diseased tissue. We present an experimental model system illustrating a new principle for improved and programmable drug-delivery, which takes ...
Directory of Open Access Journals (Sweden)
David Morrissey
2012-01-01
Full Text Available Purpose. In vivo gene therapy directed at tissues of mesenchymal origin could potentially augment healing. We aimed to assess the duration and magnitude of transene expression in vivo in mice and ex vivo in human tissues. Methods. Using bioluminescence imaging, plasmid and adenoviral vector-based transgene expression in murine quadriceps in vivo was examined. Temporal control was assessed using a doxycycline-inducible system. An ex vivo model was developed and optimised using murine tissue, and applied in ex vivo human tissue. Results. In vivo plasmid-based transgene expression did not silence in murine muscle, unlike in liver. Although maximum luciferase expression was higher in muscle with adenoviral delivery compared with plasmid, expression reduced over time. The inducible promoter cassette successfully regulated gene expression with maximum levels a factor of 11 greater than baseline. Expression was re-induced to a similar level on a temporal basis. Luciferase expression was readily detected ex vivo in human muscle and tendon. Conclusions. Plasmid constructs resulted in long-term in vivo gene expression in skeletal muscle, in a controllable fashion utilising an inducible promoter in combination with oral agents. Successful plasmid gene transfection in human ex vivo mesenchymal tissue was demonstrated for the first time.
Regularity of the interband light absorption coefficient
Indian Academy of Sciences (India)
Proc. Indian Acad. Sci. (Math. Sci.) Vol. 120, No. 3, June 2010, pp. 351–362. ... 1. Introduction. In the theory of disordered systems, one of the quantities that is ... integrated density of states, whose continuity properties and its behaviour near ...
Absorption Coefficient of Alkali Halides. Part I.
1979-03-01
Q7 A*.oj DATA’ SET ±6 4-5. 0.827 T - Elsa - Li,. 1.62, 3..%?. f..224 1 t.-.5 :.13L 312.9 15.8 9.8*6 16. t u.. t...5 ., i lo.~ 6.705 Z6.8 . 87± - c7. 9...With Synchrotron Radiation," Solid State Coimnun., 6, 575 (1968). 168. Saito, H., Saito, S., Onaka, R., and Ikeo, B., "Extreme Ultraviolet Ab- sorption
Anastasiou, A D; Strafford, S; Thomson, C L; Gardy, J; Edwards, T J; Malinowski, M; Hussain, S A; Metzger, N K; Hassanpour, A; Brown, C T A; Brown, A P; Duggal, M S; Jha, A
2018-04-15
A radical new methodology for the exogenous mineralization of hard tissues is demonstrated in the context of laser-biomaterials interaction. The proposed approach is based on the use of femtosecond pulsed lasers (fs) and Fe 3+ -doped calcium phosphate minerals (specifically in this work fluorapatite powder containing Fe 2 O 3 nanoparticles (NP)). A layer of the synthetic powder is applied to the surface of eroded bovine enamel and is irradiated with a fs laser (1040 nm wavelength, 1 GHz repetition rate, 150 fs pulse duration and 0.4 W average power). The Fe 2 O 3 NPs absorb the light and may act as thermal antennae, dissipating energy to the vicinal mineral phase. Such a photothermal process triggers the sintering and densification of the surrounding calcium phosphate crystals thereby forming a new, dense layer of typically ∼20 μm in thickness, which is bonded to the underlying surface of the natural enamel. The dispersed iron oxide NPs, ensure the localization of temperature excursion, minimizing collateral thermal damage to the surrounding natural tissue during laser irradiation. Simulated brushing trials (pH cycle and mechanical force) on the synthetic layer show that the sintered material is more acid resistant than the natural mineral of enamel. Furthermore, nano-indentation confirms that the hardness and Young's modulus of the new layers are significantly more closely matched to enamel than current restorative materials used in clinical dentistry. Although the results presented herein are exemplified in the context of bovine enamel restoration, the methodology may be more widely applicable to human enamel and other hard-tissue regenerative engineering. In this work we provide a new methodology for the mineralisation of dental hard tissues using femtosecond lasers and iron doped biomaterials. In particular, we demonstrate selective laser sintering of an iron doped fluorapatite on the surface of eroded enamel under low average power and mid
Directory of Open Access Journals (Sweden)
Claudete Regina Alcalde
1999-01-01
(AN and Saanen (SN goat breeds. Twelve kids, six of each breed, with average 19.8 kg LW, were used. Semipurified diets (low Mg content based on cracked rice, corn gluten meal and cellulose were supplemented with MgO to obtain the levels of .05 (without supplementation, .20 and .35% of Mg (% DM. The levels of Mg affected the coefficient of apparent absorption of Mg and Ca, with average values of 57.8, 73.9, and 73.2% for Mg and 55.7, 39.6 and 49.5% for Ca for diets with .05, .20, and .35% Mg, respectively. However, there was no effect of the dietary Mg level on the coefficient of apparent absorption of P, Na and K. An interaction between Mg level and breeds was observed for the real absorption of Mg. The mean for AN breed, on the level .05% Mg was 61.0% and for the levels 0.20 and 0.35% Mg, 77.2 and 73.2%, respectively. However, for SN breed the means were 73.3, 75.5 and 76.0%, for the same levels, without differences. The digestibility of dry matter, crude protein, and nitrogen free extract decreased with the crescent dietary Mg level. The fecal (7.0, 20.8 and 34.4 mg/kg LW0.75.d and urinary (3.9, 30.8 and 44.6 mg/kg LW0.75.d Mg excretion increased with the crescent dietary Mg level. There was also influence of the dietary Mg level on the blood serum Mg concentration (1.74, 2.23 and 2.80 mg/dL for .05, .20, and .35% Mg, respectively.
Shiba, Kenji; Zulkifli, Nur Elina Binti; Ishioka, Yuji
2017-06-01
In this study, we analyzed the internal electric field E and specific absorption rate (SAR) of human biological tissues surrounding an air-core coil transcutaneous energy transmission transformer. Using an electromagnetic simulator, we created a model of human biological tissues consisting of a dry skin, wet skin, fat, muscle, and cortical bone. A primary coil was placed on the surface of the skin, and a secondary coil was located subcutaneously inside the body. The E and SAR values for the model representing a 34-year-old male subject were analyzed using electrical frequencies of 0.3-1.5 MHz. The transmitting power was 15 W, and the load resistance was 38.4 Ω. The results showed that the E values were below the International Commission on Non-ionizing Radiation Protection (ICNIRP) limit for the general public exposure between the frequencies of 0.9 and 1.5 MHz, and SAR values were well below the limit prescribed by the ICNIRP for the general public exposure between the frequencies of 0.3 and 1.2 MHz.
Energy Technology Data Exchange (ETDEWEB)
Sagiyama, Koji; Kamei, Ryotaro; Honda, Hiroshi [Kyushu University, Department of Clinical Radiology, Graduate School of Medical Sciences, Fukuoka (Japan); Watanabe, Yuji; Kawanami, Satoshi [Kyushu University, Department of Molecular Imaging and Diagnosis, Graduate School of Medical Sciences, Fukuoka (Japan); Hong, Sungtak [Philips Electronics Japan, Healthcare, Tokyo (Japan); Matsumoto, Yoshihiro [Kyushu University, Departmant of Orthopaedic Surgery, Graduate School of Medical Sciences, Fukuoka (Japan)
2017-12-15
To investigate the usefulness of voxel-based analysis of standardized uptake values (SUVs) and apparent diffusion coefficients (ADCs) for evaluating soft-tissue tumour malignancy with a PET/MR system. Thirty-five subjects with either ten low/intermediate-grade tumours or 25 high-grade tumours were prospectively enrolled. Zoomed diffusion-weighted and fluorodeoxyglucose ({sup 18}FDG)-PET images were acquired along with fat-suppressed T2-weighted images (FST2WIs). Regions of interest (ROIs) were drawn on FST2WIs including the tumour in all slices. ROIs were pasted onto PET and ADC-maps to measure SUVs and ADCs within tumour ROIs. Tumour volume, SUVmax, ADCminimum, the heterogeneity and the correlation coefficients of SUV and ADC were recorded. The parameters of high- and low/intermediate-grade groups were compared, and receiver operating characteristic (ROC) analysis was also performed. The mean correlation coefficient for SUV and ADC in high-grade sarcomas was lower than that of low/intermediate-grade tumours (-0.41 ± 0.25 vs. -0.08 ± 0.34, P < 0.01). Other parameters did not differ significantly. ROC analysis demonstrated that correlation coefficient showed the best diagnostic performance for differentiating the two groups (AUC 0.79, sensitivity 96.0%, specificity 60%, accuracy 85.7%). SUV and ADC determined via PET/MR may be useful for differentiating between high-grade and low/intermediate-grade soft tissue tumours. (orig.)
International Nuclear Information System (INIS)
Schmid, Gernot; Ueberbacher, Richard; Samaras, Theodoros; Tschabitscher, Manfred; Mazal, Peter R
2007-01-01
In order to enable a detailed analysis of radio frequency (RF) absorption in the human pineal gland, the dielectric properties of a sample of 20 freshly removed pineal glands were measured less than 20 h after death. Furthermore, a corresponding high resolution numerical model of the brain region surrounding the pineal gland was developed, based on a real human tissue sample. After inserting this model into a commercially available numerical head model, FDTD-based computations for exposure scenarios with generic models of handheld devices operated close to the head in the frequency range 400-1850 MHz were carried out. For typical output power values of real handheld mobile communication devices, the obtained results showed only very small amounts of absorbed RF power in the pineal gland when compared to SAR limits according to international safety standards. The highest absorption was found for the 400 MHz irradiation. In this case the RF power absorbed inside the pineal gland (organ mass 96 mg) was as low as 11 μW, when considering a device of 500 mW output power operated close to the ear. For typical mobile phone frequencies (900 MHz and 1850 MHz) and output power values (250 mW and 125 mW) the corresponding values of absorbed RF power in the pineal gland were found to be lower by a factor of 4.2 and 36, respectively. These results indicate that temperature-related biologically relevant effects on the pineal gland induced by the RF emissions of typical handheld mobile communication devices are unlikely
Energy Technology Data Exchange (ETDEWEB)
Berrocal T, Mariella J. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia. Programa de Engenharia Nuclear]|[Universidad Nacional de Ingenieria, Lima (Peru); Roberty, Nilson C. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia. Programa de Engenharia Nuclear; Silva Neto, Antonio J. [Universidade do Estado, Nova Friburgo, RJ (Brazil). Instituto Politecnico. Dept. de Engenharia Mecanica e Energia]|[Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia. Programa de Engenharia Nuclear
2002-07-01
The solution of inverse problems in participating media where there is emission, absorption and dispersion of the radiation possesses several applications in engineering and medicine. The objective of this work is to estimative the coefficients of absorption and dispersion in two-dimensional heterogeneous participating media, using in independent form the Generalized Maximum Entropy and Levenberg Marquardt methods. Both methods are based on the solution of the direct problem that is modeled by the Boltzmann equation in cartesian geometry. Some cases testes are presented. (author)
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
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)
Energy Technology Data Exchange (ETDEWEB)
Marklund, Mette [Parker Institute: Imaging Unit, Frederiksberg Hospital (Denmark)], E-mail: mm@frh.regionh.dk; Christensen, Robin [Parker Institute: Musculoskeletal Statistics Unit, Frederiksberg Hospital (Denmark)], E-mail: robin.christensen@frh.regionh.dk; Torp-Pedersen, Soren [Parker Institute: Imaging Unit, Frederiksberg Hospital (Denmark)], E-mail: stp@frh.regionh.dk; Thomsen, Carsten [Department of Radiology, Rigshospitalet, University of Copenhagen (Denmark)], E-mail: carsten.thomsen@rh.regionh.dk; Nolsoe, Christian P. [Department of Radiology, Koge Hospital (Denmark)], E-mail: cnolsoe@dadlnet.dk
2009-01-15
Purpose: To prospectively investigate the effect on signal intensity (SI) of healthy breast parenchyma on magnetic resonance mammography (MRM) when doubling the contrast dose from 0.1 to 0.2 mmol/kg bodyweight. Materials and methods: Informed consent and institutional review board approval were obtained. Twenty-five healthy female volunteers (median age: 24 years (range: 21-37 years) and median bodyweight: 65 kg (51-80 kg)) completed two dynamic MRM examinations on a 0.6 T open scanner. The inter-examination time was 24 h (23.5-25 h). The following sequences were applied: axial T2W TSE and an axial dynamic T1W FFED, with a total of seven frames. At day 1, an i.v. gadolinium (Gd) bolus injection of 0.1 mmol/kg bodyweight (Omniscan) (low) was administered. On day 2, the contrast dose was increased to 0.2 mmol/kg (high). Injection rate was 2 mL/s (day 1) and 4 mL/s (day 2). Any use of estrogen containing oral contraceptives (ECOC) was recorded. Post-processing with automated subtraction, manually traced ROI (region of interest) and recording of the SI was performed. A random coefficient model was applied. Results: We found an SI increase of 24.2% and 40% following the low and high dose, respectively (P < 0.0001); corresponding to a 65% (95% CI: 37-99%) SI increase, indicating a moderate saturation. Although not statistically significant (P = 0.06), the results indicated a tendency, towards lower maximal SI in the breast parenchyma of ECOC users compared to non-ECOC users. Conclusion: We conclude that the contrast dose can be increased from 0.1 to 0.2 mmol/kg bodyweight, if a better contrast/noise relation is desired but increasing the contrast dose above 0.2 mmol/kg bodyweight is not likely to improve the enhancement substantially due to the moderate saturation observed. Further research is needed to determine the impact of ECOC on the relative enhancement ratio, and further studies are needed to determine if a possible use of ECOC should be considered a compromising
International Nuclear Information System (INIS)
Marklund, Mette; Christensen, Robin; Torp-Pedersen, Soren; Thomsen, Carsten; Nolsoe, Christian P.
2009-01-01
Purpose: To prospectively investigate the effect on signal intensity (SI) of healthy breast parenchyma on magnetic resonance mammography (MRM) when doubling the contrast dose from 0.1 to 0.2 mmol/kg bodyweight. Materials and methods: Informed consent and institutional review board approval were obtained. Twenty-five healthy female volunteers (median age: 24 years (range: 21-37 years) and median bodyweight: 65 kg (51-80 kg)) completed two dynamic MRM examinations on a 0.6 T open scanner. The inter-examination time was 24 h (23.5-25 h). The following sequences were applied: axial T2W TSE and an axial dynamic T1W FFED, with a total of seven frames. At day 1, an i.v. gadolinium (Gd) bolus injection of 0.1 mmol/kg bodyweight (Omniscan) (low) was administered. On day 2, the contrast dose was increased to 0.2 mmol/kg (high). Injection rate was 2 mL/s (day 1) and 4 mL/s (day 2). Any use of estrogen containing oral contraceptives (ECOC) was recorded. Post-processing with automated subtraction, manually traced ROI (region of interest) and recording of the SI was performed. A random coefficient model was applied. Results: We found an SI increase of 24.2% and 40% following the low and high dose, respectively (P < 0.0001); corresponding to a 65% (95% CI: 37-99%) SI increase, indicating a moderate saturation. Although not statistically significant (P = 0.06), the results indicated a tendency, towards lower maximal SI in the breast parenchyma of ECOC users compared to non-ECOC users. Conclusion: We conclude that the contrast dose can be increased from 0.1 to 0.2 mmol/kg bodyweight, if a better contrast/noise relation is desired but increasing the contrast dose above 0.2 mmol/kg bodyweight is not likely to improve the enhancement substantially due to the moderate saturation observed. Further research is needed to determine the impact of ECOC on the relative enhancement ratio, and further studies are needed to determine if a possible use of ECOC should be considered a compromising
International Nuclear Information System (INIS)
Ao Huilan; Xing Da; Wei Huajiang; Gu Huaimin; Wu Guoyong; Lu Jianjun
2008-01-01
The absorption coefficients, the reduced scattering coefficients and the optical penetration depths for native and coagulated human normal and adenomatous colon tissues in vitro were determined over the range of 400-1100 nm using a spectrophotometer with an internal integrating sphere system, and the inverse adding-doubling method was applied to calculate the tissue optical properties from diffuse reflectance and total transmittance measurements. The experimental results showed that in the range of 400-1100 nm there were larger absorption coefficients (P < 0.01) and smaller reduced scattering coefficients (P < 0.01) for adenomatous colon tissues than for normal colon tissues, and there were smaller optical penetration depths for adenomatous colon tissues than for normal colon tissues, especially in the near-infrared wavelength. Thermal coagulation induced significant increase of the absorption coefficients and reduced scattering coefficients for the normal and adenomatous colon tissues, and significantly reduced decrease of the optical penetration depths for the normal and adenomatous colon tissues. The smaller optical penetration depth for coagulated adenomatous colon tissues is a disadvantage for laser-induced thermotherapy (LITT) and photodynamic therapy (PDT). It is necessary to adjust the application parameters of lasers to achieve optimal therapy
A drying coefficient for building materials
DEFF Research Database (Denmark)
Scheffler, Gregor Albrecht; Plagge, Rudolf
2009-01-01
coefficient is defined which can be determined based on measured drying data. The correlation of this coefficient with the water absorption and the vapour diffusion coefficient is analyzed and its additional information content is critically challenged. As result, a drying coefficient has been derived......The drying experiment is an important element of the hygrothermal characterisation of building materials. Contrary to other moisture transport experiments as the vapour diffusion and the water absorption test, it is until now not possible to derive a simple coefficient for the drying. However......, in many cases such a coefficient would be highly appreciated, e.g. in interaction of industry and research or for the distinction and selection of suitable building materials throughout design and practise. This article first highlights the importance of drying experiments for hygrothermal...
International Nuclear Information System (INIS)
1996-01-01
The present report is a compilation of age-dependent committed effective dose coefficients for ingestion and inhalation of radionuclides of the 31 elements covered in previous CRP Publications. The biokinetic models for adults given in ICRP Publication 30 are applied to calculate these dose coefficients, except that age-specific excretion rates are used and increased gastrointestinal absorption in infants is assurred. Changes in body mass, and tissue geometry in children are also taken into account. (UK)
Kuipers, B.J.H.; Gruppen, H.
2007-01-01
The molar extinction coefficients of 20 amino acids and the peptide bond were measured at 214 nm in the presence of acetonitrile and formic acid to enable quantitative comparison of peptides eluting from reversed-phase high-performance liquid chromatography, once identified with mass spectrometry
International Nuclear Information System (INIS)
Devine, R.T.; Hsu, Hsiao-Hua
1994-01-01
The current basis for conversion coefficients for calibrating individual photon dosimeters in terms of dose equivalents is found in the series of papers by Grosswent. In his calculation the collision kerma inside the phantom is determined by calculation of the energy fluence at the point of interest and the use of the mass energy absorption coefficient. This approximates the local absorbed dose. Other Monte Carlo methods can be sued to provide calculations of the conversion coefficients. Rogers has calculated fluence-to-dose equivalent conversion factors with the Electron-Gamma Shower Version 3, EGS3, Monte Carlo program and produced results similar to Grosswent's calculations. This paper will report on calculations using the Integrated TIGER Series Version 3, ITS3, code to calculate the conversion coefficients in ICRU Tissue and in PMMA. A complete description of the input parameters to the program is given and comparison to previous results is included
International Nuclear Information System (INIS)
Ginsel, L.A.; Onderwater, J.J.M.; Daems, W.T.
1979-01-01
The transport of 3 H-fucose and 3 H-glucosamine-labelled glycoproteins in the absorptive cells of cultured human small-intestinal tissue was investigated with light- and electron-microscopical autoradiography. The findings showed that these glycoproteins were completed in the Golgi apparatus and transported in small vesicular structures to the apical cytoplasm of these cells. Since this material arrived in the cell coat on the microvilli and in the lysosome-like bodies simultaneously, a crinophagic function of these organelles in the regulation of the transport or secretion of cell-coat material was supported. In the absorptive cells of patients with fucosidosis or Hunter's type of lysosomal storage disease, a similar transport of cell-coat material to the lysosome-like bodies and a congenital defect of a lysosomal hydrolase normally involved in the degradation of cell-coat material, can explain the accumulation of this material in the dense bodies. (orig.) [de
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)
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
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)
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.
Horibe, Takuro; Ishii, Katsunori; Fukutomi, Daichi; Awazu, Kunio
2015-12-30
An estimation error of the scattering coefficient of hemoglobin in the high absorption wavelength range has been observed in optical property calculations of blood-rich tissues. In this study, the relationship between the accuracy of diffuse reflectance measurement in the integrating sphere and calculated scattering coefficient was evaluated with a system to calculate optical properties combined with an integrating sphere setup and the inverse Monte Carlo simulation. Diffuse reflectance was measured with the integrating sphere using a small incident port diameter and optical properties were calculated. As a result, the estimation error of the scattering coefficient was improved by accurate measurement of diffuse reflectance. In the high absorption wavelength range, the accuracy of diffuse reflectance measurement has an effect on the calculated scattering coefficient.
Johns, Maureen; Liu, Hanli
2003-07-01
When light interacts with tissue, it can be absorbed, scattered or reflected. Such quantitative information can be used to characterize the optical properties of tissue, differentiate tissue types in vivo, and identify normal versus diseased tissue. The purpose of this research is to develop an algorithm that determines the reduced scattering coefficient (μs") of tissues from a single optical reflectance spectrum with a small source-detector separation. The basic relationship between μs" and optical reflectance was developed using Monte Carlo simulations. This produced an analytical equation containing μs" as a function of reflectance. To experimentally validate this relationship, a 1.3-mm diameter fiber optic probe containing two 400-micron diameter fibers was used to deliver light to and collect light from Intralipid solutions of various concentrations. Simultaneous measurements from optical reflectance and an ISS oximeter were performed to validate the calculated μs" values determined by the reflectance measurement against the 'gold standard" ISS readings. The calculated μs" values deviate from the expected values by approximately -/+ 5% with Intralipid concentrations between 0.5 - 2.5%. The scattering properties within this concentration range are similar to those of in vivo tissues. Additional calculations are performed to determine the scattering properties of rat brain tissues and to discuss accuracy of the algorithm for measured samples with a broad range of the absorption coefficient (μa).
Quenching of Einstein-coefficients by photons
International Nuclear Information System (INIS)
Aumayr, F.; Skinner, C.H.; Suckewer, S.; Princeton Univ., NJ; Lee, W.
1991-02-01
Experimental evidence is presented for the change of Einstein's A-coefficients for spontaneous transitions from the upper laser level of an argon ion laser discharge due to the presence of the high-intensity laser flux. To demonstrate that this quenching effect cannot be attributed to a reduction in self-absorption of the strong spontaneous emission line, absorption and line profile measurements have been performed. Computer modelling of the reduction of self absorption due to Rabi splitting also indicated that this effect is too small to explain the observed quenching of spontaneous line emissions. 13 refs., 11 figs
Quenching of Einstein-coefficients by photons
International Nuclear Information System (INIS)
Aumayr, F.; Lee, W.; Skinner, C.H.; Suckewer, S.
1991-03-01
Experimental evidence is presented for the change of Einstein's A- coefficients for spontaneous transitions from the upper laser level of argon ion laser discharge due to the presence of the high- intensity laser flux. To demonstrate that this quenching effect cannot be attributed to a reduction in self-absorption of the strong spontaneous emission line, absorption and line profile measurements have been performed. Computer modelling of the reduction of self absorption due to Rabi splitting also indicated that this effect is too small to explain the observed quenching of spontaneous line emissions. 13 refs., 11 figs
Study on absorption, accumulation and distribution of 90Sr in yellow-feather broiler
International Nuclear Information System (INIS)
Shang Zhaorong; Xu Shiming; Zhao Wenhu; Hou Lanxin
1993-04-01
The feeding experiment was carried out for yellow-feather broiler with 90 Sr(NO 3 ) 2 having activities of 1.85 x 10 0 ∼ 1.85 x 10 4 Bq/chicken to observe the regular pattern of absorption and distribution of 90 Sr in its organs and tissues. The results are as follows: The absorption rate of 90 Sr by oral feeding is very low. The most of 90 Sr is drained away by daily excreta from the body. The half-time of its feeding is within 24 hours. The accumulated dose varies with the time and different feeding methods. The more 90 Sr is fed, the more 90 Sr is absorbed, however, the uptake rate of 90 Sr is decreasing. The distribution of 90 Sr for bone is very strong and the partition ratio is about 90%. The absorption coefficient of 90 Sr in organs and tissues of broiler is presented
Regularity on absorption and accumulation of 90Sr in yellow-feather broiler (Hypeco)
International Nuclear Information System (INIS)
Xu Shiming; Hou Lanxin; Zhao Wenhu; Li Xia; Yang Zhongyuan
1996-02-01
The feeding experiment was carried for yellow-feather broiler (Hypeco) with 90 Sr[NO 3 ] 2 having of 1.85 x 10 2 ∼1.85 x 10 5 Bq/chicken to observe the regular pattern of absorption and accumulation of 90 Sr in its organs and tissues. The absorption rate of 90 Sr by oral feeding is very low. The most of 90 Sr is drained away by daily excreta from the body. The half-time of its feeding is within 24 hours. The more 90 Sr is fed, the more 90 Sr is absorbed, however, the uptake rate of 90 Sr is decreasing. The affinity of 90 Sr for bone is very strong and the partition ratio is about 90%∼99%. The absorption coefficient of 90 Sr in organs and tissues of broiler is presented. (2 refs., 9 tabs.)
International Nuclear Information System (INIS)
Singh, V. P.; Badiger, N. M.; Vega C, H. R.
2015-10-01
Detailed information of radiation interaction, exposure and dose delivery to tissue substitutes is necessary for various branches of radiation physics. In the present investigation X- and γ-ray interaction characteristics of some tissue substitutes such as Griffith, Alderson, Frigerio, Goodman and Rossi have been studied and compared with standard tissues. Effective atomic numbers and air-kerma have been computed using mass attenuation coefficients and mass energy-absorption coefficients, respectively. Energy-absorption buildup factors for photon energy 0.015 to 15 MeV up to 40 mean free path were calculated using G-P fitting method. These investigations provide further information on the X- and γ-ray interaction of tissue substitutes for various applications in radiation physics and medical physics. (Author)
Energy Technology Data Exchange (ETDEWEB)
Singh, V. P.; Badiger, N. M. [Karnatak University, Department of Physics, Dharwad-580003, Karnataka (India); Vega C, H. R., E-mail: kudphyvps@rediffmail.com [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas, Zac. (Mexico)
2015-10-15
Detailed information of radiation interaction, exposure and dose delivery to tissue substitutes is necessary for various branches of radiation physics. In the present investigation X- and γ-ray interaction characteristics of some tissue substitutes such as Griffith, Alderson, Frigerio, Goodman and Rossi have been studied and compared with standard tissues. Effective atomic numbers and air-kerma have been computed using mass attenuation coefficients and mass energy-absorption coefficients, respectively. Energy-absorption buildup factors for photon energy 0.015 to 15 MeV up to 40 mean free path were calculated using G-P fitting method. These investigations provide further information on the X- and γ-ray interaction of tissue substitutes for various applications in radiation physics and medical physics. (Author)
Bremmer, Rolf H; van Gemert, Martin J C; Faber, Dirk J; van Leeuwen, Ton G; Aalders, Maurice C G
2013-08-01
Diffuse reflectance spectra are used to determine the optical properties of biological samples. In medicine and forensic science, the turbid objects under study often possess large absorption and/or scattering properties. However, data analysis is frequently based on the diffusion approximation to the radiative transfer equation, implying that it is limited to tissues where the reduced scattering coefficient dominates over the absorption coefficient. Nevertheless, up to absorption coefficients of 20 mm-1 at reduced scattering coefficients of 1 and 11.5 mm-1, we observed excellent agreement (r2=0.994) between reflectance measurements of phantoms and the diffuse reflectance equation proposed by Zonios et al. [Appl. Opt.38, 6628-6637 (1999)], derived as an approximation to one of the diffusion dipole equations of Farrell et al. [Med. Phys.19, 879-888 (1992)]. However, two parameters were fitted to all phantom experiments, including strongly absorbing samples, implying that the reflectance equation differs from diffusion theory. Yet, the exact diffusion dipole approximation at high reduced scattering and absorption also showed agreement with the phantom measurements. The mathematical structure of the diffuse reflectance relation used, derived by Zonios et al. [Appl. Opt.38, 6628-6637 (1999)], explains this observation. In conclusion, diffuse reflectance relations derived as an approximation to the diffusion dipole theory of Farrell et al. can analyze reflectance ratios accurately, even for much larger absorption than reduced scattering coefficients. This allows calibration of fiber-probe set-ups so that the object's diffuse reflectance can be related to its absorption even when large. These findings will greatly expand the application of diffuse reflection spectroscopy. In medicine, it may allow the use of blue/green wavelengths and measurements on whole blood, and in forensic science, it may allow inclusion of objects such as blood stains and cloth at crime
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.)
Turbid Media Extinction Coefficient for Near-Infrared Laser Radiation
International Nuclear Information System (INIS)
Dreischuh, T; Gurdev, L; Vankov, O; Stoyanov, D; Avramov, L
2015-01-01
In this work, extended investigations are performed of the extinction coefficient of Intralipid-20% dilutions in distilled water depending on the Intralipid concentration, for laser radiation wavelengths in the red and near-infrared regions covering the so-called tissue optical window. The extinction is measured by using an approach we have developed recently based on the features of the spatial intensity distribution of laser-radiation beams propagating through semi-infinite turbid media. The measurements are conducted using separately two dilution- containing plexiglass boxes of different sizes and volumes, in order to prove the appropriateness of the assumption of semi-infinite turbid medium. The experimental results for the extinction are in agreement with our previous results and with empiric formulae found by other authors concerning the wavelength dependence of the scattering coefficient of Intralipid – 10% and Intralipid – 20%. They are also in agreement with known data of the water absorptance. It is estimated as well that the wavelengths around 1320 nm would be advantageous for deep harmless sensing and diagnostics of tissues
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...
Characteristics of water absorption of beans
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...
Absorption corrections for x-ray fluorescence analysis of environmental samples
International Nuclear Information System (INIS)
Bazan, F.; Bonner, N.A.
1975-01-01
The discovery of a very simple and useful relationship between the absorption coefficient of a particular element and the ratio of incoherent to coherent scattering by the sample containing the element is discussed. By measuring the absorption coefficients for a few elements in a few samples, absorption coefficients for many elements in an entire set of similar samples can be obtained. (auth)
Absorption corrections for x-ray fluorescence analysis of environmental samples
International Nuclear Information System (INIS)
Bazan, F.; Bonner, N.A.
1976-01-01
The discovery of a very simple and useful relationship between the absorption coefficient of a particular element and the ratio of incoherent to coherent scattering by the sample containing the element is discussed. By measuring the absorption coefficients for a few elements in a few samples, absorption coefficients for many elements in an entire set of similar samples can be obtained
The use of a reference absorber for absorption measurements in a reverberation chamber
DEFF Research Database (Denmark)
Nolan, Melanie; Vercammen, Martijn; Jeong, Cheol-Ho
2014-01-01
The statistical incidence absorption coefficient is measured in a reverberation room according to ISO 354. This absorption coefficient is referred to as Sabine absorption coefficient, which assumes the chambe r to be completely diffuse. It is known that the reproducibility of these results is poo...
Photoelectric absorption cross sections with variable abundances
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.
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)
International Nuclear Information System (INIS)
Grosenick, Dirk; Wabnitz, Heidrun; Moesta, K Thomas; Mucke, Joerg; Schlag, Peter M; Rinneberg, Herbert
2005-01-01
Within a clinical trial on scanning time-domain optical mammography reported on in a companion publication (part I), craniocaudal and mediolateral projection optical mammograms were recorded from 154 patients, suspected of having breast cancer. Here we report on in vivo optical properties of the subset of 87 histologically validated carcinomas which were visible in optical mammograms recorded at two or three near-infrared wavelengths. Tumour absorption and reduced scattering coefficients were derived from distributions of times of flight of photons recorded at the tumour site employing the model of diffraction of photon density waves by a spherical inhomogeneity, located in an otherwise homogeneous tissue slab. Effective tumour radii, taken from pathology, and tumour location along the compression direction, deduced from off-axis optical scans of the tumour region, were included in the analysis as prior knowledge, if available. On average, tumour absorption coefficients exceeded those of surrounding healthy breast tissue by a factor of about 2.5 (670 nm), whereas tumour reduced scattering coefficients were larger by about 20% (670 nm). From absorption coefficients at 670 nm and 785 nm total haemoglobin concentration and blood oxygen saturation were deduced for tumours and surrounding healthy breast tissue. Apart from a few outliers total haemoglobin concentration was observed to be systematically larger in tumours compared to healthy breast tissue. In contrast, blood oxygen saturation was found to be a poor discriminator for tumours and healthy breast tissue; both median values of blood oxygen saturation are the same within their statistical uncertainties. However, the ratio of total haemoglobin concentration over blood oxygen saturation further improves discrimination between tumours and healthy breast tissue. For 29 tumours detected in optical mammograms recorded at three wavelengths (670 nm, 785 nm, 843 nm or 884 nm), scatter power was derived from transport
Vapor-Phase Infrared Absorptivity Coefficient of HN1
2013-08-01
the boil-off of a bulk liquid nitrogen tank, across an alumina Soxhlet thimble in a glass holder filled with the analyte. A vapor–liquid...with mass spectrometry (MS) yielded the results shown in Table 3. Table 3. Results from Analysis of HN1 Sample Used for Determination of...2 yields (3) Equation 3 can then be solved at each frequency using a least-squares approach. This was
Lifshitz tails for the interband light absorption coefficient
Indian Academy of Sciences (India)
of self-adjoint operators on H is called measurable if the family ..... This is a direct verification to see that the diagonal lines λ1 + λ2 = const passing ..... [2] Carmona R and Lacroix J, Spectral Theory of Random Schrödinger Operators (Boston:.
Vapor-Phase Infrared Absorptivity Coefficient of Cyclohexyl Isothiocyanate
National Research Council Canada - National Science Library
Samuels, Alan C; Miles, Jr., Ronald W; Williams, Barry R; Hulet, Melissa S
2008-01-01
...)) at a spectral resolution of 0.125 cm(-1). The chemical used in the feedstock was subjected to a rigorous analysis by gas chromatography-mass spectrometry, nuclear magnetic resonance, and Karl-Fischer titration to verify its purity...
Determination of sedimentation rates and absorption coefficient of ...
African Journals Online (AJOL)
2+ has a higher sedimentation rate of 5.10x10-2 s-1 while Ni2+ has the lowest sedimentation rates of 1.10 x10-3. The rate of sedimentation of the metal carbonates decreased in the order: Zn2+ > Cd2+ > Cu2+ > Co2+ > Ni2+. The order ...
International Nuclear Information System (INIS)
Chantler, C.T.
2000-01-01
Reliable knowledge of the complex x-ray form factor [Re(f ) ] and the photoelectric attenuation coefficient (σ PE ) is required for crystallography, medical diagnosis, radiation safety, and XAFS studies. Discrepancies between currently used theoretical approaches of 200% exist for numerous elements from 1 to 3 keV x-ray energies. The key discrepancies are due to the smoothing of edge structure, the use of nonrelativistic wave functions, and the lack of appropriate convergence of wave functions. This paper addresses these key discrepancies and derives new theoretical results of substantially higher accuracy in near-edge soft x-ray regions. The high-energy limitations of the current approach are also illustrated. The energy range covered is 0.1 to 10 keV. The associated figures and tabulation demonstrate the current comparison with alternate theory and with available experimental data. In general, experimental data are not sufficiently accurate to establish the errors and inadequacies of theory at this level. However, the best experimental data and the observed experimental structure as a function of energy are strong indicators of the validity of the current approach. New developments in experimental measurement hold great promise in making critical comparisons with theory in the near future
Energy Technology Data Exchange (ETDEWEB)
Alhamami, Mosa; Kolios, Michael C.; Tavakkoli, Jahan, E-mail: jtavakkoli@ryerson.ca [Department of Physics, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3 (Canada)
2014-05-15
Purpose: The aims of this study are: (a) to investigate the capability of photoacoustic (PA) method in detecting high-intensity focused ultrasound (HIFU) treatments in muscle tissuesin vitro; and (b) to determine the optical properties of HIFU-treated and native tissues in order to assist in the interpretation of the observed contrast in PA detection of HIFU treatments. Methods: A single-element, spherically concaved HIFU transducer with a centre frequency of 1 MHz was utilized to create thermal lesions in chicken breast tissuesin vitro. To investigate the detectability of HIFU treatments photoacoustically, PA detection was performed at 720 and 845 nm on seven HIFU-treated tissue samples. Within each tissue sample, PA signals were acquired from 22 locations equally divided between two regions of interest within two volumes in tissue – a HIFU-treated volume and an untreated volume. Optical spectroscopy was then carried out on 10 HIFU-treated chicken breast specimens in the wavelength range of 500–900 nm, in 1-nm increments, using a spectrophotometer with an integrating sphere attachment. The authors’ optical spectroscopy raw data (total transmittance and diffuse reflectance) were used to obtain the optical absorption and reduced scattering coefficients of HIFU-induced thermal lesions and native tissues by employing the inverse adding-doubling method. The aforementioned interaction coefficients were subsequently used to calculate the effective attenuation coefficient and light penetration depth of HIFU-treated and native tissues in the wavelength range of 500–900 nm. Results: HIFU-treated tissues produced greater PA signals than native tissues at 720 and 845 nm. At 720 nm, the averaged ratio of the peak-to-peak PA signal amplitude of HIFU-treated tissue to that of native tissue was 3.68 ± 0.25 (mean ± standard error of the mean). At 845 nm, the averaged ratio of the peak-to-peak PA signal amplitude of HIFU-treated tissue to that of native tissue was 3.75
Subgap Absorption in Conjugated Polymers
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.
Outlines of ICRP publication 74 and new dose conversion coefficients for external radiation
International Nuclear Information System (INIS)
Yamaguchi, Yasuhiro
1998-01-01
Combined task group of ICRP and ICRU reported the ICRP Publication 74 (1996) which is a summary report of their collection, analysis and evaluation of many data and dose conversion coefficients. Concerning the new coefficients, the author described this review as follows: History until Publication 74. Doses recommended at present: for protection quantity, the mean absorption dose of organ and tissue, equivalent dose and effective dose and for operational quantity, the ambient dose equivalent, directional dose equivalent and individual dose equivalent. Changes which can have an influence on the dose evaluation; introduction of radiation weighting factor (WR), changing of tissue weighting factor (WR), changing of the equation for Q-L relation and updating of physical data. New dose conversion coefficients; for photon, neutron and electron. Comparison of new and present coefficients; concerning the quality factor Q, particularly for neutron Q. New relations of protection and operational quantities; for field and individual monitoring. General conclusion of Publication 74. The Publication gives a certain direction for problems in evaluation of external exposure dose which have been discussed since the ICRP Fundamental Recommendation 1990 was issued. However, there still remain many problems especially in validity of the WR and of equation for Q-L relation. (K.H.)
Loch, Christian; Zakelj, Simon; Kristl, Albin; Nagel, Stefan; Guthoff, Rudolf; Weitschies, Werner; Seidlitz, Anne
2012-08-30
To treat ophthalmic diseases like glaucoma or inflammatory disorders topically applied ophthalmic formulations such as eye drops are usually used. In addition, novel ophthalmic implants releasing drug substances locally into different parts of the eye are available today. In the work presented here, the permeability coefficients of selected drugs (ciprofloxacin hydrochloride, lidocaine hydrochloride, timolol maleate) for ophthalmic tissues were determined using side-by-side diffusion chambers (so-called Ussing chambers). Sclera, conjunctiva, cornea, choroidea-retina-complex and a complex of conjunctiva-sclera-choroidea-retina were excised from fresh porcine, rabbit and bovine eyes. In the porcine eye tissues the highest P(app) values were obtained for conjunctiva with the exception of lidocaine. Therefore, it can be estimated that a certain amount of drug diffuses or is transported through conjunctiva after application. The P(app) values for sclera were also higher than those for cornea and even more, the surface area of sclera which is available for drug absorption is much larger than that of cornea when applying an implant. The obtained permeability coefficients for sclera and conjunctiva indicate that the administration of periocular implants can be an alternative to topically applied formulations. The complexes of the tissues were a significantly (p<0.01) stronger barrier to the investigated substances than the separated tissues. Distinct differences in permeability coefficients between the investigated animal tissues were observed. Overall the highest P(app) values for all mounted tissues were obtained with the rabbit, followed by porcine and bovine eyes. Because of these distinct interspecies differences one must be very careful when selecting the proper animal model for the permeability experiments. Copyright © 2012 Elsevier B.V. All rights reserved.
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
Coefficient of restitution of model repaired car body parts
D. Hadryś; M. Miros
2008-01-01
Purpose: The qualification of influence of model repaired car body parts on the value of coefficient of restitution and evaluation of impact energy absorption of model repaired car body parts.Design/methodology/approach: Investigation of plastic strain and coefficient of restitution of new and repaired model car body parts with using impact test machine for different impact energy.Findings: The results of investigations show that the value of coefficient of restitution changes with speed (ene...
Transport Coefficients of Fluids
Eu, Byung Chan
2006-01-01
Until recently the formal statistical mechanical approach offered no practicable method for computing the transport coefficients of liquids, and so most practitioners had to resort to empirical fitting formulas. This has now changed, as demonstrated in this innovative monograph. The author presents and applies new methods based on statistical mechanics for calculating the transport coefficients of simple and complex liquids over wide ranges of density and temperature. These molecular theories enable the transport coefficients to be calculated in terms of equilibrium thermodynamic properties, and the results are shown to account satisfactorily for experimental observations, including even the non-Newtonian behavior of fluids far from equilibrium.
Tissue dose in thorotrast patients
International Nuclear Information System (INIS)
Kaul, A.; Noffz, W.
1978-01-01
Absorbed doses to the liver, spleen, red marrow, lungs, kidneys, and to various parts of bone tissue were calculated for long-term burdens of intravascularly injected Thorotrast. The estimates were performed for typical injection levels of 10, 30, 50 and 100 ml, based upon best estimates of 232 Th tissue distribution, and steady state activity ratios between the subsequent daughters. Correcting for the α-particle self absorption within Thorotrast aggregates, the mean α-dose to a standard 70-kg man at 30 yr after the injection 0f 25 ml of Thorotrast is 750 rad to the liver, 2100 rad to the spleen, 270 rad to the red marrow, 60-620 rad in various parts of the lung, and 13 rad to the kidneys. Dose rates to various parts of bone tissue (bone surface, compact, and cancellous bone) were estimated by applying the ICRP model on alkaline earth metabolism to the continuous translocation of thorium daughters to bone and to the formation of thorium daughters by decay within bone tissue. The average dose to calcified bone from translocated 224 Ra with its daughters is 18 rad at 30 yr after the injection of 25 ml of Thorotrast. Considering the Spiess-Mays risk coefficient of 0.9-1.7% bone sarcoma/ 100 rad of average skeletal dose from 224 Ra and its daughters, the induction of 1.6-3.1 bone sarcomas per 1000 Thorotrast patients is predicted. (author)
Finlay, Jarod C.; Zhu, Timothy C.; Dimofte, Andreea; Stripp, Diana C. H.; Malkowicz, S. B.; Whittington, Richard; Miles, Jeremy; Glatstein, Eli; Hahn, Stephen M.
2004-06-01
A continuing challenge in photodynamic therapy is the accurate in vivo determination of the optical properties of the tissue being treated. We have developed a method for characterizing the absorption and scattering spectra of prostate tissue undergoing PDT treatment. Our current prostate treatment protocol involves interstitial illumination of the organ via cylindrical diffusing optical fibers (CDFs) inserted into the prostate through clear catheters. We employ one of these catheters to insert an isotropic white light point source into the prostate. An isotropic detection fiber connected to a spectrograph is inserted into a second catheter a known distance away. The detector is moved along the catheter by a computer-controlled step motor, acquiring diffuse light spectra at 2 mm intervals along its path. We model the fluence rate as a function of wavelength and distance along the detector"s path using an infinite medium diffusion theory model whose free parameters are the absorption coefficient μa at each wavelength and two variables A and b which characterize the reduced scattering spectrum of the form μ"s = Aλ-b. We analyze our spectroscopic data using a nonlinear fitting algorithm to determine A, b, and μa at each wavelength independently; no prior knowledge of the absorption spectrum or of the sample"s constituent absorbers is required. We have tested this method in tissue simulating phantoms composed of intralipid and the photosensitizer motexafin lutetium (MLu). The MLu absorption spectrum recovered from the phantoms agrees with that measured in clear solution, and μa at the MLu absorption peak varies linearly with concentration. The ´"s spectrum reported by the fit is in agreement with the known scattering coefficient of intralipid. We have applied this algorithm to spectroscopic data from human patients sensitized with MLu (2 mg kg-1) acquired before and after PDT. Before PDT, the absorption spectra we measure include the characteristic MLu absorption
Bent Electro-Absorption Modulator
DEFF Research Database (Denmark)
2002-01-01
by applying a variable electric or electronmagnetic field. The modulation of the complex refractive index results in a modulation of the refractive index contrast and the absorption coefficient for the waveguide at the frequency of the light. By carefully adjusting the composition of the semiconducting...... components and the applied electric field in relation to the frequency of the modulated radiation, the bending losses (and possibly coupling losses) will provide extinction of light guided by the bent waveguide section. The refractive index contract may be modulated while keeping the absorption coefficient......The present invention relates to a method and a device for modulating optical signals based on modulating bending losses in bend, quantum well semiconductor waveguide sections. The complex refractive index of the optical active semiconducting components of the waveguide section is modulated...
Energy Technology Data Exchange (ETDEWEB)
Ferreira, C.C., E-mail: cassio.c.ferreira@gmail.co [Departamento de Fisica, Universidade Federal de Sergipe, Postal Code 353, Sergipe-SE 49100-000 (Brazil); Ximenes Filho, R.E.M., E-mail: raimundoximenes@hotmail.co [Departamento de Fisica, Universidade Federal de Sergipe, Postal Code 353, Sergipe-SE 49100-000 (Brazil); Vieira, J.W., E-mail: jwvieira@br.inter.ne [Centro Federal de Educacao Tecnologica de Pernambuco (CEFET-PE), Av. Professor Luiz Freire, 500 Curado, CEP 50740-540, Recife (Brazil); Escola Politecnica de Pernambuco, Universidade de Pernambuco (EPP/UPE), Rua Benfica, 455, Madalena, CEP 50720-001, Recife (Brazil); Tomal, A., E-mail: alessandratomal@pg.ffclrp.usp.b [Departamento de Fisica e Matematica, FFCLRP, Universidade de Sao Paulo, Ribeirao Preto-SP 14040-90 (Brazil); Poletti, M.E., E-mail: poletti@ffclrp.usp.b [Departamento de Fisica e Matematica, FFCLRP, Universidade de Sao Paulo, Ribeirao Preto-SP 14040-90 (Brazil); Garcia, C.A.B., E-mail: cgarcia@ufs.b [Departamento de Quimica, Universidade Federal de Sergipe, Postal Code 353, Sergipe-SE 49100-000 (Brazil); Maia, A.F., E-mail: afmaia@ufs.b [Departamento de Fisica, Universidade Federal de Sergipe, Postal Code 353, Sergipe-SE 49100-000 (Brazil)
2010-08-15
Tissue-equivalent materials to be used as substitutes for human brain tissue in dosimetry for diagnostic radiology have been investigated in terms of calculated total mass attenuation coefficient ({mu}/{rho}), calculated mass energy-absorption coefficient ({mu}{sub en}/{rho}) and absorbed dose. Measured linear attenuation coefficients ({mu}) have been used for benchmarking the calculated total mass attenuation coefficient ({mu}/{rho}). The materials examined were bolus, nylon (registered) , orange articulation wax, red articulation wax, PMMA (polymethylmethacrylate), bees wax, paraffin I, paraffin II, pitch and water. The results show that water is the best substitute for brain among the materials investigated. The average percentage differences between the calculated {mu}/{rho} and {mu}{sub en}/{rho} coefficients for water and those for brain were 1.0% and 2.5%, respectively. Absorbed doses determined by Monte Carlo methods confirm water as being the best brain substitute to be used in dosimetry for diagnostic radiology, showing maximum difference of 0.01%. Additionally this study showed that PMMA, a material often used for the manufacturing of head phantoms for computed tomography, cannot be considered to be a suitable substitute for human brain tissue in dosimetry.
Kheireddine, Malika; Ouhssain, Mustapha; Calleja, Maria Ll.; Moran, Xose Anxelu G.; Sarma, Y.V.B; Tiwari, Surya Prakash; Jones, Burton
2018-01-01
distribution of the absorption coefficient of CDOM. The spectral absorption coefficients were determined from 400nm to 740nm using a WETLabs ac-s hyper-spectral spectrophotometer. In general, we found a latitudinal gradient in the CDOM absorption coefficient
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.
Particulate absorption properties in the Red Sea from hyperspectral particulate absorption spectra
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.
Attenuation coefficients of soils
International Nuclear Information System (INIS)
Martini, E.; Naziry, M.J.
1989-01-01
As a prerequisite to the interpretation of gamma-spectrometric in situ measurements of activity concentrations of soil radionuclides the attenuation of 60 to 1332 keV gamma radiation by soil samples varying in water content and density has been investigated. A useful empirical equation could be set up to describe the dependence of the mass attenuation coefficient upon photon energy for soil with a mean water content of 10%, with the results comparing well with data in the literature. The mean density of soil in the GDR was estimated at 1.6 g/cm 3 . This value was used to derive the linear attenuation coefficients, their range of variation being 10%. 7 figs., 5 tabs. (author)
Heat transfer modelling of pulsed laser-tissue interaction
Urzova, J.; Jelinek, M.
2018-03-01
Due to their attributes, the application of medical lasers is on the rise in numerous medical fields. From a biomedical point of view, the most interesting applications are the thermal interactions and the photoablative interactions, which effectively remove tissue without excessive heat damage to the remaining tissue. The objective of this work is to create a theoretical model for heat transfer in the tissue following its interaction with the laser beam to predict heat transfer during medical laser surgery procedures. The dimensions of the ablated crater (shape and ablation depth) were determined by computed tomography imaging. COMSOL Multiphysics software was used for temperature modelling. The parameters of tissue and blood, such as density, specific heat capacity, thermal conductivity and diffusivity, were calculated from the chemical ratio. The parameters of laser-tissue interaction, such as absorption and reflection coefficients, were experimentally determined. The parameters of the laser beam were power density, repetition frequency, pulse length and spot dimensions. Heat spreading after laser interaction with tissue was captured using a Fluke thermal camera. The model was verified for adipose tissue, skeletal muscle tissue and heart muscle tissue.
Absorption and Metabolism of Xanthophylls
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 bee...
Ong, Yi Hong; Padawer-Curry, Jonah; Finlay, Jarod C.; Kim, Michele M.; Dimofte, Andreea; Cengel, Keith; Zhu, Timothy C.
2018-02-01
PDT efficacy depends on the concentration of photosensitizer, oxygen, and light delivery in patient tissues. In this study, we measure the in-vivo distribution of important dosimetric parameters, namely the tissue optical properties (absorption μa (λ) and scattering μs ' (λ) coefficients), photofrin concentration (cphotofrin), blood oxygen saturation (%StO2), and total hemoglobin concentration (THC), before and after PDT. We characterize the inter- and intra-patient heterogeneity of these quantities and explore how these properties change as a result of PDT treatment. The result suggests the need for real-time dosimetry during PDT to optimize the treatment condition depending on the optical and physiological properties.
Analytical model of diffuse reflectance spectrum of skin tissue
Energy Technology Data Exchange (ETDEWEB)
Lisenko, S A; Kugeiko, M M; Firago, V A [Belarusian State University, Minsk (Belarus); Sobchuk, A N [B.I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, Minsk (Belarus)
2014-01-31
We have derived simple analytical expressions that enable highly accurate calculation of diffusely reflected light signals of skin in the spectral range from 450 to 800 nm at a distance from the region of delivery of exciting radiation. The expressions, taking into account the dependence of the detected signals on the refractive index, transport scattering coefficient, absorption coefficient and anisotropy factor of the medium, have been obtained in the approximation of a two-layer medium model (epidermis and dermis) for the same parameters of light scattering but different absorption coefficients of layers. Numerical experiments on the retrieval of the skin biophysical parameters from the diffuse reflectance spectra simulated by the Monte Carlo method show that commercially available fibre-optic spectrophotometers with a fixed distance between the radiation source and detector can reliably determine the concentration of bilirubin, oxy- and deoxyhaemoglobin in the dermis tissues and the tissue structure parameter characterising the size of its effective scatterers. We present the examples of quantitative analysis of the experimental data, confirming the correctness of estimates of biophysical parameters of skin using the obtained analytical expressions. (biophotonics)
Absorption of acoustic waves in La3Ga5SiO14 monocrystals
International Nuclear Information System (INIS)
Mansfel'd, G.D.; Bezdelkin, V.V.; Freik, A.D.; Kucheryavaya, E.S.
1995-01-01
Frequency dependences of longitudinal and transverse acoustic wave absorption coefficient in the basic crystallographic La 3 Ga 5 SiO 14 directions are measured by composite resonator method. The obtained values of absorption coefficient for all directions appear to be lower or approximately equal to the values of absorption coefficient in quartz monocrystals. Application of the resonator methods allows one to study factors affecting the resonator high-quality as well. 9 refs., 4 figs
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.
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.
The Truth About Ballistic Coefficients
Courtney, Michael; Courtney, Amy
2007-01-01
The ballistic coefficient of a bullet describes how it slows in flight due to air resistance. This article presents experimental determinations of ballistic coefficients showing that the majority of bullets tested have their previously published ballistic coefficients exaggerated from 5-25% by the bullet manufacturers. These exaggerated ballistic coefficients lead to inaccurate predictions of long range bullet drop, retained energy and wind drift.
Evolution of absorption machines; Evolution des machines a absorption
Energy Technology Data Exchange (ETDEWEB)
Soide, I; Klemsdal, E [Gaz de France (GDF), 75 - Paris (France); Le Goff, P; Hornut, J M [LSGC-ENSIC, 54 - Nancy (France)
1998-12-31
Most of todays absorption air-conditioning machineries use the lithium bromide-water pair. The most performing can operate at a 150-160 deg. C, the temperature being limited by the corrosion resistance of metals with respect to LiBr solutions. Also, there is a revival of interest for water-ammonia systems. These systems require the use of a rectification column which reduces the coefficient of performance. Higher thermal performances are reached with hydrocarbon pairs and ternary mixtures (water-methanol-LiBr etc..). This paper presents different schemes of refrigerating heat pumps based on these different systems. (J.S.)
Evolution of absorption machines; Evolution des machines a absorption
Energy Technology Data Exchange (ETDEWEB)
Soide, I.; Klemsdal, E. [Gaz de France (GDF), 75 - Paris (France); Le Goff, P.; Hornut, J.M. [LSGC-ENSIC, 54 - Nancy (France)
1997-12-31
Most of todays absorption air-conditioning machineries use the lithium bromide-water pair. The most performing can operate at a 150-160 deg. C, the temperature being limited by the corrosion resistance of metals with respect to LiBr solutions. Also, there is a revival of interest for water-ammonia systems. These systems require the use of a rectification column which reduces the coefficient of performance. Higher thermal performances are reached with hydrocarbon pairs and ternary mixtures (water-methanol-LiBr etc..). This paper presents different schemes of refrigerating heat pumps based on these different systems. (J.S.)
Evaluation of laser radiation regimes at thermal tissue destruction
Ivanov, Anatoly; Kazaryan, Mishik A.; Molodykh, E. I.; Shchetinkina, T. A.
1996-01-01
The existing methods of laser destruction of biotissues, widely spread in surgery and coagulation action, are based on local heat emission in the tissues after light absorption. Here we present the results of the simulation of tissues heat destruction, taking into account the influence of blood and lymph circulation on the processes of heat transfer. The problem is adapted to the case of liver tissue with tumor. A liver is considered as a capillary-porous body with internal blood circulation. Heatconductivity and tissue-blood heat transfer are considered. Heat action is assumed to be implemented with contact laser scalpel. The mathematical model consists of two inhomogeneous nonlinear equations of heatconductivity with spherical symmetry. Nonstationary temperature fields of tissue and blood are determined and the main parameters are: (1) coefficients of heatconductivity and capacitance of blood and tissue, (2) blood and tissue density, (3) total metabolic energy, (4) volume coefficient accounting for heat-exchange between tissue and blood, and (5) blood circulation velocity. The power of laser radiation was taken into account in boundary conditions set for the center of coagulated tissue volume. We also took into account the process connected with changing of substance phase (vaporization). The original computer programs allow one to solve the problem varying in a wide range of the main parameters. Reasonable agreement was found between the calculation results and the experimental data for operations on microsamples and on test animals. It was demonstrated, in particular, that liver tissue coagulation regime is achieved at 10 W laser power during 25 s. The coagulation radius of 0.7 cm with the given tumor radius of 0.5 cm corresponds to the real clinical situation in case of metastasis liver affection.
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
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
A Review: Characteristics of Noise Absorption Material
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.
International Nuclear Information System (INIS)
Chou, D.-Y.; Yang, M.-H.; Zhao Hui; Liang Zhichao; Sun, M.-T.
2009-01-01
Observed acoustic power in magnetic regions is lower than the quiet Sun because of absorption, emissivity reduction, and local suppression of solar acoustic waves in magnetic regions. In the previous studies, we have developed a method to measure the coefficients of absorption, emissivity reduction, and local suppression of sunspots. In this study, we go one step further to measure the spatial distributions of three coefficients in two active regions, NOAA 9055 and 9057. The maps of absorption, emissivity reduction, and local suppression coefficients correlate with the magnetic map, including plage regions, except the emissivity reduction coefficient of NOAA 9055 where the emissivity reduction coefficient is too weak and lost among the noise.
Numerical study of surface plasmon enhanced nonlinear absorption and refraction.
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.
A practical relation between atomic numbers and alpha coefficients
International Nuclear Information System (INIS)
Lachance, G.R.
1980-01-01
A first approximation indicates that fundamental alpha coefficients for a given analyte vary as a function of the ratio of their respective atomic number raised to a power. This simple rule applies mainly at the limits (i.e., when the weight fraction of analyte i, Wsub(i) is of the order of 0.0 or 1.0) in cases of absorption and weak enhancement. The relation thus provides a means of generating coefficients for the system i-k from experimental data obtained on system i-j and a means of verifying experimental alphas, since arrays of coefficients must show a high degree of concordance. (author)
Optical measurements of absorption changes in two-layered diffusive media
International Nuclear Information System (INIS)
Fabbri, Francesco; Sassaroli, Angelo; Henry, Michael E; Fantini, Sergio
2004-01-01
We have used Monte Carlo simulations for a two-layered diffusive medium to investigate the effect of a superficial layer on the measurement of absorption variations from optical diffuse reflectance data processed by using: (a) a multidistance, frequency-domain method based on diffusion theory for a semi-infinite homogeneous medium; (b) a differential-pathlength-factor method based on a modified Lambert-Beer law for a homogeneous medium and (c) a two-distance, partial-pathlength method based on a modified Lambert-Beer law for a two-layered medium. Methods (a) and (b) lead to a single value for the absorption variation, whereas method (c) yields absorption variations for each layer. In the simulations, the optical coefficients of the medium were representative of those of biological tissue in the near-infrared. The thickness of the first layer was in the range 0.3-1.4 cm, and the source-detector distances were in the range 1-5 cm, which is typical of near-infrared diffuse reflectance measurements in tissue. The simulations have shown that (1) method (a) is mostly sensitive to absorption changes in the underlying layer, provided that the thickness of the superficial layer is ∼0.6 cm or less; (2) method (b) is significantly affected by absorption changes in the superficial layer and (3) method (c) yields the absorption changes for both layers with a relatively good accuracy of ∼4% for the superficial layer and ∼10% for the underlying layer (provided that the absorption changes are less than 20-30% of the baseline value). We have applied all three methods of data analysis to near-infrared data collected on the forehead of a human subject during electroconvulsive therapy. Our results suggest that the multidistance method (a) and the two-distance partial-pathlength method (c) may better decouple the contributions to the optical signals that originate in deeper tissue (brain) from those that originate in more superficial tissue layers
Optical absorption of charged excitons in semiconducting carbon nanotubes
DEFF Research Database (Denmark)
Rønnow, Troels Frimodt; Pedersen, Thomas Garm; Cornean, Horia
2012-01-01
In this article we examine the absorption coefficient of charged excitons in carbon nanotubes. We investigate the temperature and damping dependence of the absorption spectra. We show that the trion peak in the spectrum is asymmetric for temperatures greater than approximately 1 K whereas...
Errors in instumental neutron activation analysis caused by matrix absorption
International Nuclear Information System (INIS)
Croudace, I.W.
1979-01-01
Instrumental neutron activation analysis of the geochemically important rare earth elements, together with Ta, Hf and U involves energies below 150 keV where absorption of radiation by the sample becomes inceasingly important. Determinations of the total mass absorption coefficients have been made. (C.F.)
Molar extinction coefficients of solutions of some organic compounds
Indian Academy of Sciences (India)
(C4H8O2), succinimide (C4H5NO2) as estimated from the measured absorbance of. 7 radiations in their ... species in the solution and ε is called the molar absorptivity or extinction coefficient. (l mol-1cm-1 or ... Integration of eq. (4) leads to.
... 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 ...
On the Kendall Correlation Coefficient
Stepanov, Alexei
2015-01-01
In the present paper, we first discuss the Kendall rank correlation coefficient. In continuous case, we define the Kendall rank correlation coefficient in terms of the concomitants of order statistics, find the expected value of the Kendall rank correlation coefficient and show that the later is free of n. We also prove that in continuous case the Kendall correlation coefficient converges in probability to its expected value. We then propose to consider the expected value of the Kendall rank ...
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
Aerosol Absorption Measurements in MILAGRO.
Gaffney, J. S.; Marley, N. A.; Arnott, W. P.; Paredes-Miranda, L.; Barnard, J. C.
2007-12-01
to carbonyl- and nitro- functional groups on conjugated and aromatic organic structures (e.g. PAH, and terpene derived products). Using 12-hour fine (0.1-1.0 micron) aerosol samples collected in the field on quartz filters, uv/vis and infrared spectra were obtained in the laboratory using integrating spheres and diffuse reflectance spectroscopy, respectively. An inter-comparison of the "real-time" measurements made by the photo-acoustic, aethalometer and MAAP techniques have been described. In addition, the in situ aethalometer (seven-channel) results are compared with continuous integrating sphere uv-visible spectra to examine the angstrom absorption coefficient variance. These results will be briefly overviewed and the specific posters detailing these results will be highlighted highlighted. This work was performed as part of the Department of Energy's Megacity Aerosol Experiment - Mexico City under the support of the Atmospheric Science Program. "This researchwas supported by the Office of Science (BER), U. S. Department of Energy, Grant No. DE-FG02-07ER64329.
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
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).
Energy Technology Data Exchange (ETDEWEB)
Gerde, P. [National Inst. for Working Life, Solna (Sweden); Muggenburg, B.A.; Thornton-Manning, J.R. [and others
1995-12-01
Most chemically induced lung cancer originates in the epithelial cells in the airways. Common conceptions are that chemicals deposited on the airway surface are rapidly absorbed through mucous membranes, limited primarily by the rate of blood perfusion in the mucosa. It is also commonly thought that for chemicals to induce toxicity at the site of entry, they must be either rapidly reactive, readily metabolizable, or especially toxic to the tissues at the site of entry. For highly lipophilic toxicants, there is a third option. Our mathematical model predicts that as lipophilicity increases, chemicals partition more readily into the cellular lipid membranes and diffuse more slowly through the tissues. Therefore, absorption of very lipophilic compounds will be almost entirely limited by the rate of diffusion through the epithelium rather than by perfusion of the capillary bed in the subepithelium. We have reported on a preliminary model for absorption through mucous membranes of any substance with a lipid/aqueous partition coefficient larger than one. The purpose of this work was to experimentally validate the model in Beagle dogs. This validated model on toxicant absorption in the airway mucosa will improve risk assessment of inhaled
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
Moderator temperature coefficient in BWR core
International Nuclear Information System (INIS)
Naito, Yoshitaka
1977-01-01
Temperature dependences of infinite multiplication factor k sub(infinity) and neutron leakage from the core must be examined for estimation of moderator temperature coefficient. Temperature dependence on k sub(infinity) has been investigated by many researchers, however, the dependence on neutron leakage of a BWR with cruciformed control rods has hardly been done. Because there are difficulties and necessity on calculations of three space dimensional and multi-energy groups neutron distribution in a BWR core. In this study, moderator temperature coefficients of JPDR-II (BWR) core were obtained by calculation with DIFFUSION-ACE, which is newly developed three-dimensional multi-group computer code. The results were compared with experimental data measured from 20 to 275 0 C of the moderator temperature and the good agreement was obtained between calculation and measurement. In order to evaluate neutron leakage from the core, the other two calculations were carried out, adjusting criticality by uniform absorption rate and by material buckling. The former underestimated neutron leakage and the latter overestimated it. Discussion on the results shows that in order to estimate the temperature coefficient of BWR, neutron leakage must be evaluated precisely, therefore the calculation at actual pattern of control rods is necessary. (auth.)
A solid tissue phantom for photon migration studies
International Nuclear Information System (INIS)
Cubeddu, Rinaldo; Pifferi, Antonio; Taroni, Paola; Torricelli, Alessandro; Valentini, Gianluca
1997-01-01
A solid tissue phantom made of agar, Intralipid and black ink is described and characterized. The preparation procedure is fast and easily implemented with standard laboratory equipment. An instrumentation for time-resolved transmittance measurements was used to determine the optical properties of the phantom. The absorption and the reduced scattering coefficients are linear with the ink and Intralipid concentrations, respectively. A systematic decrease of the reduced scattering coefficient dependent on the agar content is observed, but can easily be managed. The phantom is highly homogeneous and shows good repeatability among different preparations. Moreover, agar inclusions can be easily embedded in either solid or liquid matrixes, and no artefacts are caused by the solid - solid or solid - liquid interfaces. This allows one to produce reliable and realistic inhomogeneous phantoms with known optical properties, particularly interesting for studies on optical imaging through turbid media. (author)
[The percutaneous absorption of diclofenac].
Riess, W; Schmid, K; Botta, L; Kobayashi, K; Moppert, J; Schneider, W; Sioufi, A; Strusberg, A; Tomasi, M
1986-07-01
The percutaneous absorption of diclofenac diethylammonium 1.16% (w/w) in a combination of emulsion cream and gel (Voltaren Emulgel) and of diclofenac sodium 1% (w/w) in a cream formulation (Voltaren cream) was investigated in guinea-pig, rabbit and man. The percutaneous absorption of diclofenac sodium in guinea-pig was 3 to 6% of the dose when the cream formulation in doses of 320, 100 or 40 mg was applied on 10 cm2 of occluded skin and left in place for 6 h. The transdermal delivery of 14C-labelled diclofenac yielded plateau plasma concentrations of radiotracer from 1.5 h after application until removal of the residual cream. Subsequently the steady state drug depots in the skin and muscle tissue were depleted promptly. During daily administration the steady state levels in the muscle tissue in proximity to the application site were about 3 times higher than in distant muscle tissue. By topical application on knee joints of rabbits diclofenac penetrated into the patellar ligament, the adipose corpus and the synovial fluid. In man the percutaneous absorption was 6% of the dose when the Emulgel formulation was spread by 5 mg/cm2 and left for 12 h on non-occluded skin. The pattern of metabolites of diclofenac in human urine was the same after topical and oral administration. In man, upon daily topical administration of 3 times 2.5 g cream formulation (10 mg/cm2) the diclofenac steady state plasma levels were 20 to 40 nmol/l.(ABSTRACT TRUNCATED AT 250 WORDS)
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.
International Nuclear Information System (INIS)
Ambe, S.; Shinonaga, T.; Ozaki, T.; Enomoto, S.; Yasuda, H.; Uchida, S.
1999-01-01
The selective absorption coefficient, which is a parameter of an uptake model of radionuclides by plants, was determined for various radionuclides by a multitracer technique. Komatsuna, Brassica rapa var. perviridis, was hydroponically cultivated in a nutrient solution containing a multitracer for 1 day. Nutrient concentration dependence of the selective absorption coefficient of various elements from Be to Re was obtained separately for leaves and roots. The selective absorption coefficients of these elements were, in general, found to decrease with an increase in the concentration of nutrient solutions. Regression equations of the power function for the selective absorption coefficients and the concentration of nutrient solutions were obtained for the leaves and roots. The effects of photon flux and growth stage of plants on the selective absorption coefficients were also studied. It was found that the photon flux influenced the accumulation of radionuclides in the roots but had no significant effect on the selective absorption coefficients for the leaves in 1-day cultivation with the multitracer. The selective absorption coefficients of Mn and Zn in the leaves of the plants at the development stage were higher than those at the maturation stage. For the other elements, no significant effects of the growth stage on the selective absorption coefficients were observed. (author)
Electron cyclotron absorption in Tokamak plasmas in the presence of radial transport of particles
International Nuclear Information System (INIS)
Rosa, Paulo R. da S.; Ziebell, Luiz F.
1998-01-01
We use quasilinear theory to study effects of particle radial transport on the electron cyclotron absorption coefficient by a current carrying plasma, in a tokamak modelated as a plasma slab. Our numerical results indicate significant modification in the profile of the electron cyclotron absorption coefficient when transport is taken into account relative to the situation without transport. (author)
Statistical evidences of absorption at high latitudes
International Nuclear Information System (INIS)
Fesenko, B.I.
1980-01-01
Evidences are considered which indicate to the significant effect of the irregular interstellar absorption at high latitudes b. The number density of faint galaxies grows with the increasing |b| even at the values of |b| exceeding 50 deg. The effects of interstellar medium are traced even in the directions of the stars and globular clusters with very low values of the colour excess. The coefficient of absorption, Asub(B)=0.29+-0.05, was estimated from the colours of the bright E-galaxies [ru
[Study on lead absorption in pumpkin by atomic absorption spectrophotometry].
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.
International Nuclear Information System (INIS)
Li, H.; Chang, C.; Cheng, H. H.; Sun, G.; Soref, R. A.
2016-01-01
We report an investigation on the absorption mechanism of a GeSn photodetector with 2.4% Sn composition in the active region. Responsivity is measured and absorption coefficient is calculated. Square root of absorption coefficient linearly depends on photon energy indicating an indirect transition. However, the absorption coefficient is found to be at least one order of magnitude higher than that of most other indirect materials, suggesting that the indirect optical absorption transition cannot be assisted only by phonon. Our analysis of absorption measurements by other groups on the same material system showed the values of absorption coefficient on the same order of magnitude. Our study reveals that the strong enhancement of absorption for the indirect optical transition is the result of alloy disorder from the incorporation of the much larger Sn atoms into the Ge lattice that are randomly distributed.
Quadrature formulas for Fourier coefficients
Bojanov, Borislav
2009-09-01
We consider quadrature formulas of high degree of precision for the computation of the Fourier coefficients in expansions of functions with respect to a system of orthogonal polynomials. In particular, we show the uniqueness of a multiple node formula for the Fourier-Tchebycheff coefficients given by Micchelli and Sharma and construct new Gaussian formulas for the Fourier coefficients of a function, based on the values of the function and its derivatives. © 2009 Elsevier B.V. All rights reserved.
International Nuclear Information System (INIS)
Trivedi, Ashish; Basu, Soumyadipta; Mitra, Kunal
2005-01-01
The use of short pulse laser for minimally invasive detection scheme has become an indispensable tool in the technological arsenal of modern medicine and biomedical engineering. In this work, a time-resolved technique has been used to detect tumors/inhomogeneities in tissues by measuring transmitted and reflected scattered temporal optical signals when a short pulse laser source is incident on tissue phantoms. A parametric study involving different scattering and absorption coefficients of tissue phantoms and inhomogeneities, size of inhomogeneity as well as the detector position is performed. The experimental measurements are validated with a numerical solution of the transient radiative transport equation obtained by using discrete ordinates method. Thus, both simultaneous experimental and numerical studies are critical for predicting the optical properties of tissues and inhomogeneities from temporal scattered optical signal measurements
Coefficient Alpha: A Reliability Coefficient for the 21st Century?
Yang, Yanyun; Green, Samuel B.
2011-01-01
Coefficient alpha is almost universally applied to assess reliability of scales in psychology. We argue that researchers should consider alternatives to coefficient alpha. Our preference is for structural equation modeling (SEM) estimates of reliability because they are informative and allow for an empirical evaluation of the assumptions…
Coefficient estimates of negative powers and inverse coefficients for ...
Indian Academy of Sciences (India)
and the inequality is sharp for the inverse of the Koebe function k(z) = z/(1 − z)2. An alternative approach to the inverse coefficient problem for functions in the class S has been investigated by Schaeffer and Spencer [27] and FitzGerald [6]. Although, the inverse coefficient problem for the class S has been completely solved ...
Measuring of heat transfer coefficient
DEFF Research Database (Denmark)
Henningsen, Poul; Lindegren, Maria
Subtask 3.4 Measuring of heat transfer coefficient Subtask 3.4.1 Design and setting up of tests to measure heat transfer coefficient Objective: Complementary testing methods together with the relevant experimental equipment are to be designed by the two partners involved in order to measure...... the heat transfer coefficient for a wide range of interface conditions in hot and warm forging processes. Subtask 3.4.2 Measurement of heat transfer coefficient The objective of subtask 3.4.2 is to determine heat transfer values for different interface conditions reflecting those typically operating in hot...
Montcel, Bruno; Chabrier, Renée; Poulet, Patrick
2006-12-01
Time-resolved diffuse optical methods have been applied to detect hemodynamic changes induced by cerebral activity. We describe a near infrared spectroscopic (NIRS) reconstruction free method which allows retrieving depth-related information on absorption variations. Variations in the absorption coefficient of tissues have been computed over the duration of the whole experiment, but also over each temporal step of the time-resolved optical signal, using the microscopic Beer-Lambert law.Finite element simulations show that time-resolved computation of the absorption difference as a function of the propagation time of detected photons is sensitive to the depth profile of optical absorption variations. Differences in deoxyhemoglobin and oxyhemoglobin concentrations can also be calculated from multi-wavelength measurements. Experimental validations of the simulated results have been obtained for resin phantoms. They confirm that time-resolved computation of the absorption differences exhibited completely different behaviours, depending on whether these variations occurred deeply or superficially. The hemodynamic response to a short finger tapping stimulus was measured over the motor cortex and compared to experiments involving Valsalva manoeuvres. Functional maps were also calculated for the hemodynamic response induced by finger tapping movements.
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
Quantitative frequency-domain fluorescence spectroscopy in tissues and tissue-like media
Cerussi, Albert Edward
1999-09-01
In the never-ending quest for improved medical technology at lower cost, modern near-infrared optical spectroscopy offers the possibility of inexpensive technology for quantitative and non-invasive diagnoses. Hemoglobin is the dominant chromophore in the 700-900 nm spectral region and as such it allows for the optical assessment of hemoglobin concentration and tissue oxygenation by absorption spectroscopy. However, there are many other important physiologically relevant compounds or physiological states that cannot be effectively sensed via optical methods because of poor optical contrast. In such cases, contrast enhancements are required. Fluorescence spectroscopy is an attractive component of optical tissue spectroscopy. Exogenous fluorophores, as well as some endogenous ones, may furnish the desperately needed sensitivity and specificity that is lacking in near-infrared optical tissue spectroscopy. The main focus of this thesis was to investigate the generation and propagation of fluorescence photons inside tissues and tissue-like media (i.e., scattering dominated media). The standard concepts of fluorescence spectroscopy have been incorporated into a diffusion-based picture that is sometimes referred to as photon migration. The novelty of this work lies in the successful quantitative recovery of fluorescence lifetimes, absolute fluorescence quantum yields, fluorophore concentrations, emission spectra, and both scattering and absorption coefficients at the emission wavelength from a tissue-like medium. All of these parameters are sensitive to the fluorophore local environment and hence are indicators of the tissue's physiological state. One application demonstrating the capabilities of frequency-domain lifetime spectroscopy in tissue-like media is a study of the binding of ethidium bromide to bovine leukocytes in fresh milk. Ethidium bromide is a fluorescent dye that is commonly used to label DNA, and hence visualize chromosomes in cells. The lifetime of
Insulin analogues with improved absorption characteristics.
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.
Optical Characterization of Tissue Phantoms Using a Silicon Integrated fdNIRS System on Chip.
Sthalekar, Chirag C; Miao, Yun; Koomson, Valencia Joyner
2017-04-01
An interface circuit with signal processing and digitizing circuits for a high frequency, large area avalanche photodiode (APD) has been integrated in a 130 nm BiCMOS chip. The system enables the absolute oximetry of tissue using frequency domain Near Infrared Spectroscopy (fdNIRS). The system measures the light absorbed and scattered by the tissue by measuring the reduction in the amplitude of signal and phase shift introduced between the light source and detector which are placed a finite distance away from each other. The received 80 MHz RF signal is downconverted to a low frequency and amplified using a heterodyning scheme. The front-end transimpedance amplifier has a 3-level programmable gain that increases the dynamic range to 60 dB. The phase difference between an identical reference channel and the optical channel is measured with a 0.5° accuracy. The detectable current range is [Formula: see text] and with a 40 A/W reponsivity using the APD, power levels as low as 500 pW can be detected. Measurements of the absorption and reduced scattering coefficients of solid tissue phantoms using this system are compared with those using a commercial instrument with differences within 30%. Measurement of a milk based liquid tissue phantom show an increase in absorption coefficient with addition of black ink. The miniaturized circuit serves as an efficiently scalable system for multi-site detection for applications in neonatal cerebral oximetry and optical mammography.
Gamma ray attenuation coefficient measurement for neutron-absorbent materials
International Nuclear Information System (INIS)
Jalali, Majid; Mohammadi, Ali
2008-01-01
The compounds Na 2 B 4 O 7 , H 3 BO 3 , CdCl 2 and NaCl and their solutions attenuate gamma rays in addition to neutron absorption. These compounds are widely used in the shielding of neutron sources, reactor control and neutron converters. Mass attenuation coefficients of gamma related to the four compounds aforementioned, in energies 662, 778.9, 867.38, 964.1, 1085.9, 1173, 1212.9, 1299.1,1332 and 1408 keV, have been determined by the γ rays transmission method in a good geometry setup; also, these coefficients were calculated by MCNP code. A comparison between experiments, simulations and Xcom code has shown that the study has potential application for determining the attenuation coefficient of various compound materials. Experiment and computation show that H 3 BO 3 with the lowest average Z has the highest gamma ray attenuation coefficient among the aforementioned compounds
High temperature measurement of water vapor absorption
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.
Pérez-Gutiérrez, Francisco G.; Camacho-López, Santiago; Aguilar, Guillermo
2011-07-01
Nanosecond long laser pulses are used in medical applications where precise tissue ablation with minimal thermal and mechanical collateral damage is required. When a laser pulse is incident on a material, optical energy will be absorbed by a combination of linear and nonlinear absorption according to both: laser light irradiance and material properties. In the case of water or gels, the first results in heat generation and thermoelastic expansion; while the second results in an expanding plasma formation that launches a shock wave and a cavitation/boiling bubble. Plasma formation due to nonlinear absorption of nanosecond laser pulses is originated by a combination of multiphoton ionization and thermionic emission of free electrons, which is enhanced when the material has high linear absorption coefficient. In this work, we present three experimental approaches to study pressure transients originated when 6 ns laser pulses are incident on agar gels and water with varying linear absorption coefficient, using laser radiant exposures above and below threshold for bubble formation: (a) PVDF sensors, (b) Time-resolved shadowgraphy and (c) Time-resolved interferometry. The underlying hypothesis is that pressure transients are composed of the superposition of both: shock wave originated by hot expanding plasma resulting from nonlinear absorption of optical energy and, thermoelastic expansion originated by heat generation due to linear absorption of optical energy. The objective of this study is to carry out a comprehensive experimental analysis of the mechanical effects that result when tissue models are irradiated with nanosecond laser pulses to elucidate the relative contribution of linear and nonlinear absorption to bubble formation. Furthermore, we investigate cavitation bubble formation with temperature increments as low as 3 °C.
Directory of Open Access Journals (Sweden)
Bertan Hallacoglu
Full Text Available We introduce a multi-distance, frequency-domain, near-infrared spectroscopy (NIRS method to measure the optical coefficients of two-layered media and the thickness of the top layer from diffuse reflectance measurements. This method features a direct solution based on diffusion theory and an inversion procedure based on the Levenberg-Marquardt algorithm. We have validated our method through Monte Carlo simulations, experiments on tissue-like phantoms, and measurements on the forehead of three human subjects. The Monte Carlo simulations and phantom measurements have shown that, in ideal two-layered samples, our method accurately recovers the top layer thickness (L, the absorption coefficient (µ a and the reduced scattering coefficient (µ' s of both layers with deviations that are typically less than 10% for all parameters. Our method is aimed at absolute measurements of hemoglobin concentration and saturation in cerebral and extracerebral tissue of adult human subjects, where the top layer (layer 1 represents extracerebral tissue (scalp, skull, dura mater, subarachnoid space, etc. and the bottom layer (layer 2 represents cerebral tissue. Human subject measurements have shown a significantly greater total hemoglobin concentration in cerebral tissue (82±14 µM with respect to extracerebral tissue (30±7 µM. By contrast, there was no significant difference between the hemoglobin saturation measured in cerebral tissue (56%±10% and extracerebral tissue (62%±6%. To our knowledge, this is the first time that an inversion procedure in the frequency domain with six unknown parameters with no other prior knowledge is used for the retrieval of the optical coefficients and top layer thickness with high accuracy on two-layered media. Our absolute measurements of cerebral hemoglobin concentration and saturation are based on the discrimination of extracerebral and cerebral tissue layers, and they can enhance the impact of NIRS for cerebral hemodynamics and
Sound absorption with green materials
Trematerra, Amelia; Lombardi, Ilaria
2017-07-01
Green materials are a valid alternative to traditional materials that are by-products of processing oil. At the end of their useful life, green materials can be disposed of without polluting the environment. They are now being used in the construction and automotive industries. While, studies are currently being carried out in the aviation sector on the use of green materials for non-structural components of airplanes. Green materials can be used to improve the acoustic comfort inside buildings as well as mitigate reverberation, echoes effects and reduce the transmission of noise between rooms. In this paper, the acoustic measurements of the properties of green materials are reported. The absorption coefficient of samples of the materials were measured in the frequency range from 200 Hz to 2,000 Hz with an impedance tube, with the flow resistance being measured.
Time domain diffuse optical spectroscopy: In vivo quantification of collagen in breast tissue
Taroni, Paola; Pifferi, Antonio; Quarto, Giovanna; Farina, Andrea; Ieva, Francesca; Paganoni, Anna Maria; Abbate, Francesca; Cassano, Enrico; Cubeddu, Rinaldo
2015-05-01
Time-resolved diffuse optical spectroscopy provides non-invasively the optical characterization of highly diffusive media, such as biological tissues. Light pulses are injected into the tissue and the effects of light propagation on re-emitted pulses are interpreted with the diffusion theory to assess simultaneously tissue absorption and reduced scattering coefficients. Performing spectral measurements, information on tissue composition and structure is derived applying the Beer law to the measured absorption and an empiric approximation to Mie theory to the reduced scattering. The absorption properties of collagen powder were preliminarily measured in the range of 600-1100 nm using a laboratory set-up for broadband time-resolved diffuse optical spectroscopy. Optical projection images were subsequently acquired in compressed breast geometry on 218 subjects, either healthy or bearing breast lesions, using a portable instrument for optical mammography that operates at 7 wavelengths selected in the range 635-1060 nm. For all subjects, tissue composition was estimated in terms of oxy- and deoxy-hemoglobin, water, lipids, and collagen. Information on tissue microscopic structure was also derived. Good correlation was obtained between mammographic breast density (a strong risk factor for breast cancer) and an optical index based on collagen content and scattering power (that accounts mostly for tissue collagen). Logistic regression applied to all optically derived parameters showed that subjects at high risk for developing breast cancer for their high breast density can effectively be identified based on collagen content and scattering parameters. Tissue composition assessed in breast lesions with a perturbative approach indicated that collagen and hemoglobin content are significantly higher in malignant lesions than in benign ones.
Solar absorption surface panel
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.
Nutrition and magnesium absorption
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
Zeeman atomic absorption spectroscopy
International Nuclear Information System (INIS)
Loos-Vollebregt, M.T.C. de.
1980-01-01
A new method of background correction in atomic absorption spectroscopy has recently been introduced, based on the Zeeman splitting of spectral lines in a magnetic field. A theoretical analysis of the background correction capability observed in such instruments is presented. A Zeeman atomic absorption spectrometer utilizing a 50 Hz sine wave modulated magnetic field is described. (Auth.)
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
Distribution of temperature coefficient density for muons in the atmosphere
Directory of Open Access Journals (Sweden)
Kuzmenko V.S.
2017-12-01
Full Text Available To date, several dozens of new muon detectors have been built. When studying cosmic-ray intensity variations with these detectors, located deep in the atmosphere, it is necessary to calculate all characteristics, including the distribution of temperature coefficient density for muons in the atmosphere, taking into account their specific geometry. For this purpose, we calculate the density of temperature coefficients of muon intensity in the atmosphere at various zenith angles of detection at sea level and at various depths underground for different absorption ranges of primary protons and pions in the atmosphere.
Intrinsic defect oriented visible region absorption in zinc oxide films
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.
Probabilistic optimization of safety coefficients
International Nuclear Information System (INIS)
Marques, M.; Devictor, N.; Magistris, F. de
1999-01-01
This article describes a reliability-based method for the optimization of safety coefficients defined and used in design codes. The purpose of the optimization is to determine the partial safety coefficients which minimize an objective function for sets of components and loading situations covered by a design rule. This objective function is a sum of distances between the reliability of the components designed using the safety coefficients and a target reliability. The advantage of this method is shown on the examples of the reactor vessel, a vapour pipe and the safety injection circuit. (authors)
Artificial semi-rigid tissue sensitized with natural pigments: Effect of photon radiations
Directory of Open Access Journals (Sweden)
Adnan Jaradat
2011-01-01
Full Text Available Background: A new approach for evaluating the optical penetration depth and testing its validity with Monte Carlo simulations and Kubelka-Munk theory is used for artificial semi-rigid tissue sensitized with natural pigments. Photodynamic therapy is a promising cancer treatment in which a photosensitizing drug concentrates in malignant cells and is activated by visible light at certain wavelength. Materials and Methods: Cheap artificial semi-rigid tissue incorporated with scattering and absorbing materials along with some other composites comparable to normal human tissue has been performed. The optical parameters as measured with different conditions and calculated with various techniques are investigated. Results: The probability of interaction of light with tissue is very high when exposed to light in presence of Cichorium pumilum and RBCs followed by photohemolysis or/and photodegradation. The optical penetration depth calculated by linear absorption coefficient ranges from 0.63 to 2.85 mm is found to be comparable to those calculated using Kubelka-Munk theory or Monte Carlo simulation (range from 0.78 to 2.42 mm. The ratio of absorption to the scattering is independent of thickness and decreases with increasing irradiation time. Moreover, the optical parameters as well as their ratios are in very good agreement in the two approaches of calculation. The values of absorption and scattering coefficients are independent of thickness. Furthermore, the average photon ranges in the samples containing no scattering and absorbing materials are about three times greater than those samples containing scattering materials. Conclusion: Our results suggest that light propagation with optical properties presented in this work could be applicable in diagnostic and therapeutic of the human biological tissue for photodynamic therapy.
UV laser long-path absorption spectroscopy
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
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.
Quadrature formulas for Fourier coefficients
Bojanov, Borislav; Petrova, Guergana
2009-01-01
We consider quadrature formulas of high degree of precision for the computation of the Fourier coefficients in expansions of functions with respect to a system of orthogonal polynomials. In particular, we show the uniqueness of a multiple node
Diffusion coefficient for anomalous transport
International Nuclear Information System (INIS)
1986-01-01
A report on the progress towards the goal of estimating the diffusion coefficient for anomalous transport is given. The gyrokinetic theory is used to identify different time and length scale inherent to the characteristics of plasmas which exhibit anomalous transport
Fuel Temperature Coefficient of Reactivity
Energy Technology Data Exchange (ETDEWEB)
Loewe, W.E.
2001-07-31
A method for measuring the fuel temperature coefficient of reactivity in a heterogeneous nuclear reactor is presented. The method, which is used during normal operation, requires that calibrated control rods be oscillated in a special way at a high reactor power level. The value of the fuel temperature coefficient of reactivity is found from the measured flux responses to these oscillations. Application of the method in a Savannah River reactor charged with natural uranium is discussed.
Properties of Traffic Risk Coefficient
Tang, Tie-Qiao; Huang, Hai-Jun; Shang, Hua-Yan; Xue, Yu
2009-10-01
We use the model with the consideration of the traffic interruption probability (Physica A 387(2008)6845) to study the relationship between the traffic risk coefficient and the traffic interruption probability. The analytical and numerical results show that the traffic interruption probability will reduce the traffic risk coefficient and that the reduction is related to the density, which shows that this model can improve traffic security.
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
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
An in silico skin absorption model for fragrance materials.
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
Effect of morphology and solvent on two-photon absorption of nano zinc oxide
Energy Technology Data Exchange (ETDEWEB)
Kavitha, M.K. [Department of Chemistry, Indian Institute of Space Science and Technology, Valiamala, Thiruvananthapuram 695547, Kerala (India); Haripadmam, P.C.; Gopinath, Pramod; Krishnan, Bindu [Department of Physics, Indian Institute of Space Science and Technology, Valiamala, Thiruvananthapuram 695547, Kerala (India); John, Honey, E-mail: honey@iist.ac.in [Department of Chemistry, Indian Institute of Space Science and Technology, Valiamala, Thiruvananthapuram 695547, Kerala (India)
2013-05-15
Highlights: ► ZnO nanospheres and triangular structures synthesis by novel precipitation technique. ► The effect of precursor concentration on the size and shape of nano ZnO. ► Open aperture Z-scan measurements of the ZnO nanoparticle dispersions. ► Nanospheres exhibit higher two photon absorption coefficient than triangular nanostructures. ► Nanospheres dispersed in water exhibit higher two photon absorption coefficient than its dispersion in 2-propanol. - Abstract: In this paper, we report the effect of morphology and solvent on the two-photon absorption of nano zinc oxide. Zinc oxide nanoparticles in two different morphologies like nanospheres and triangular nanostructures are synthesized by novel precipitation technique and their two-photon absorption coefficient is measured using open aperture Z-scan technique. Experimental results show that the zinc oxide nanospheres exhibit higher two-photon absorption coefficient than the zinc oxide triangular nanostructures. The zinc oxide nanospheres dispersed in water exhibit higher two-photon absorption coefficient than that of its dispersion in 2-propanol. The zinc oxide nanospheres dispersed in water shows a decrease in two-photon absorption coefficient with an increase in on-axis irradiance. The result confirms the dependence of shape and solvent on the two-photon absorption of nano zinc oxide.
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
Vacuum ultraviolet (VUV) absorption spectra of chromatin and its components
International Nuclear Information System (INIS)
Dodonova, N.Y.; Kiseleva, M.N.; Petrov, M.Y.; Tsyganenko, N.M.; Bubyakina, V.V.; Chikhirzhina, G.I.
1984-01-01
The electron absorption spectra of thin films of chromatin and chromatin components in the ultraviolet region (140-280 nm) were investigated. The absorption coefficients μ(lambda) of chromatin, nucleosomes with and without histone H1, total histones (TH), and DNA were compared. The spectra of nucleosomes differ from the sum-spectrum of DNA plus TH. The chromatin and nucleosome spectra are not similar in the spectral region of 190-160 nm. The lack of additivity of absorption coefficients at different wavelengths may be explained by different conformational changes of DNA, TH in nucleosomes and chromatin during the process of drying aqueous solutions for the preparation of thin films. The μ(lambda) values are useful for an estimate of the DNA and TH absorption in chromatin and nucleosomes in discussing UV and VUV irradiation damages. (Auth.)
THE PERMEABILITY OF THE SCLERAL TISSUE FOR ULTRAVIOLET A IN THE EXPERIMENT
Directory of Open Access Journals (Sweden)
M. M. Bikbov
2017-01-01
Full Text Available Purpose: to evaluate the permeability of the scleral tissue for ultraviolet A (UVA.Materials and Methods. The study was conducted on 15 cadaver porcine eyes. Rectangular scleral flap 12*15 mm was cut out from each eyeball. The thickness of the sample was measured with a digital caliper. The outer surface of the scleral flap was irradiated with ultraviolet A. A sensor of the UV-radiometer was placed under the sample. It measured the UVA irradiance passing through the sclera. The absorption coefficient of ultraviolet A by the sclera was calculated from the formula derived from the Bouguer-Lambert Beer law: , where E0 — the absorption coefficient, mm-1; — irradiance of the transmitted light, mW/cm2; I0 — irradiance of the received light, mW/cm2; — thickness of the sclera, mm.Results. The absorption coefficient of ultraviolet A by the sclera was 4,91±0,43 mm-1. According literature the threshold damaging radiation for retina is 7.7 J/cm2. Substituting these values in the converted formula of the Bouguer-Lambert-Beer law, we can derive an equation for calculating the threshold UVA irradiation dose of the sclera: , where 0 — the threshold UVA irradiation dose of the sclera, J/cm2; — the base of the natural logarithm; — thickness of the sclera, mm.Conclusion. The absorption coefficient of ultraviolet A by the cadaver porcine sclera is 4,91±0,43 mm-1. The derived formula of the threshold UVA irradiation dose of the sclera calculating allows to avoid the threatening for the retina procedure parameters in the performance of the scleral crosslinking with riboflavin/UVA.
Clustering Coefficients for Correlation Networks.
Masuda, Naoki; Sakaki, Michiko; Ezaki, Takahiro; Watanabe, Takamitsu
2018-01-01
Graph theory is a useful tool for deciphering structural and functional networks of the brain on various spatial and temporal scales. The clustering coefficient quantifies the abundance of connected triangles in a network and is a major descriptive statistics of networks. For example, it finds an application in the assessment of small-worldness of brain networks, which is affected by attentional and cognitive conditions, age, psychiatric disorders and so forth. However, it remains unclear how the clustering coefficient should be measured in a correlation-based network, which is among major representations of brain networks. In the present article, we propose clustering coefficients tailored to correlation matrices. The key idea is to use three-way partial correlation or partial mutual information to measure the strength of the association between the two neighboring nodes of a focal node relative to the amount of pseudo-correlation expected from indirect paths between the nodes. Our method avoids the difficulties of previous applications of clustering coefficient (and other) measures in defining correlational networks, i.e., thresholding on the correlation value, discarding of negative correlation values, the pseudo-correlation problem and full partial correlation matrices whose estimation is computationally difficult. For proof of concept, we apply the proposed clustering coefficient measures to functional magnetic resonance imaging data obtained from healthy participants of various ages and compare them with conventional clustering coefficients. We show that the clustering coefficients decline with the age. The proposed clustering coefficients are more strongly correlated with age than the conventional ones are. We also show that the local variants of the proposed clustering coefficients (i.e., abundance of triangles around a focal node) are useful in characterizing individual nodes. In contrast, the conventional local clustering coefficients were strongly
Clustering Coefficients for Correlation Networks
Directory of Open Access Journals (Sweden)
Naoki Masuda
2018-03-01
Full Text Available Graph theory is a useful tool for deciphering structural and functional networks of the brain on various spatial and temporal scales. The clustering coefficient quantifies the abundance of connected triangles in a network and is a major descriptive statistics of networks. For example, it finds an application in the assessment of small-worldness of brain networks, which is affected by attentional and cognitive conditions, age, psychiatric disorders and so forth. However, it remains unclear how the clustering coefficient should be measured in a correlation-based network, which is among major representations of brain networks. In the present article, we propose clustering coefficients tailored to correlation matrices. The key idea is to use three-way partial correlation or partial mutual information to measure the strength of the association between the two neighboring nodes of a focal node relative to the amount of pseudo-correlation expected from indirect paths between the nodes. Our method avoids the difficulties of previous applications of clustering coefficient (and other measures in defining correlational networks, i.e., thresholding on the correlation value, discarding of negative correlation values, the pseudo-correlation problem and full partial correlation matrices whose estimation is computationally difficult. For proof of concept, we apply the proposed clustering coefficient measures to functional magnetic resonance imaging data obtained from healthy participants of various ages and compare them with conventional clustering coefficients. We show that the clustering coefficients decline with the age. The proposed clustering coefficients are more strongly correlated with age than the conventional ones are. We also show that the local variants of the proposed clustering coefficients (i.e., abundance of triangles around a focal node are useful in characterizing individual nodes. In contrast, the conventional local clustering coefficients
Clustering Coefficients for Correlation Networks
Masuda, Naoki; Sakaki, Michiko; Ezaki, Takahiro; Watanabe, Takamitsu
2018-01-01
Graph theory is a useful tool for deciphering structural and functional networks of the brain on various spatial and temporal scales. The clustering coefficient quantifies the abundance of connected triangles in a network and is a major descriptive statistics of networks. For example, it finds an application in the assessment of small-worldness of brain networks, which is affected by attentional and cognitive conditions, age, psychiatric disorders and so forth. However, it remains unclear how the clustering coefficient should be measured in a correlation-based network, which is among major representations of brain networks. In the present article, we propose clustering coefficients tailored to correlation matrices. The key idea is to use three-way partial correlation or partial mutual information to measure the strength of the association between the two neighboring nodes of a focal node relative to the amount of pseudo-correlation expected from indirect paths between the nodes. Our method avoids the difficulties of previous applications of clustering coefficient (and other) measures in defining correlational networks, i.e., thresholding on the correlation value, discarding of negative correlation values, the pseudo-correlation problem and full partial correlation matrices whose estimation is computationally difficult. For proof of concept, we apply the proposed clustering coefficient measures to functional magnetic resonance imaging data obtained from healthy participants of various ages and compare them with conventional clustering coefficients. We show that the clustering coefficients decline with the age. The proposed clustering coefficients are more strongly correlated with age than the conventional ones are. We also show that the local variants of the proposed clustering coefficients (i.e., abundance of triangles around a focal node) are useful in characterizing individual nodes. In contrast, the conventional local clustering coefficients were strongly
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.
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
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...
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)
Wang, Fei; Liu, Jun-yan; Wang, Xiao-chun; Wang, Yang
2018-03-01
In this paper, a one-dimensional (1D) thermal-wave model coupled diffuse-photon-density-wave for three-layer dental tissues using modulated laser stimulation was employed to illustrate the relationship between dental caries characteristic (i.e. caries layer thickness, optical absorption coefficient and optical scattering coefficient) and photothermal radiometry (PTR) signal. Experimental investigation of artificial caries was carried out using PTR scanning imaging. The PTR amplitude and phase delay were increased with dental demineralized treatment. The local caries characteristic parameters were obtained by the best-fitting method based on the 1D thermal-wave model. The PTR scanning imaging measurements illustrated that the optical absorption coefficient and scattering coefficient of caries region were much higher than those of the healthy enamel area. The demineralization thickness of caries region was measured by PTR scanning imaging and its average value shows in good agreement with the digital microscope. Experimental results show that PTR scanning imaging has the merits of high contrast for local inhomogeneity of dental caries; furthermore, this method is an allowance to provide a flexibility for non-contact quantitative evaluation of dental caries.
Exercise, Insulin Absorption Rates, and Artificial Pancreas Control
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.
Absorption of water and lubricating oils into porous nylon
Bertrand, P. A.
1995-01-01
Oil and water absorption from air into sintered porous nylon can be described by infiltration into the pores of the material. This process can be modeled by a diffusion-like mechanism. For water absorption, we find a formal diffusion coefficient of 1.5 x 10(exp -4)sq cm/min when the nylon is initially dry. The diffusion coefficient is 4 x 10(exp -6)sq cm/min when the nylon is oil-impregnated prior to air exposure. In a 52% RH atmosphere, dry nylon absorbs 3% w/w water, and oil-impregnated nylon absorbs 0.6% w/w water. For oil absorption there are three steps: (1) surface absorption and infiltration into (2) larger and (3) smaller pores. Surface absorption is too fast to be measured in these experiments. The diffusion coefficient for the second step is 6 x 10(exp -4)sq cm/min for SRG-60 oil into dry nylon and 4 x 10(exp -4)sq cm/min for air-equilibrated nylon. The diffusion coefficient for the third step is about 1 x 10(exp -6)sq cm/min for both cases. The total amount of oil absorbed is 31% w/w. The interaction between water and nylon is not as strong as that between water and cotton-phenolic: oil can replace water, and only a small amount of water can enter previously oil-impregnated nylon.
Morphology of urethral tissues
Müller, Bert; Schulz, Georg; Herzen, Julia; Mushkolaj, Shpend; Bormann, Therese; Beckmann, Felix; Püschel, Klaus
2010-09-01
Micro computed tomography has been developed to a powerful technique for the characterization of hard and soft human and animal tissues. Soft tissues including the urethra, however, are difficult to be analyzed, since the microstructures of interest exhibit X-ray absorption values very similar to the surroundings. Selective staining using highly absorbing species is a widely used approach, but associated with significant tissue modification. Alternatively, one can suitably embed the soft tissue, which requires the exchange of water. Therefore, the more recently developed phase contrast modes providing much better contrast of low X-ray absorbing species are especially accommodating in soft tissue characterization. The present communication deals with the morphological characterization of sheep, pig and human urethras on the micrometer scale taking advantage of micro computed tomography in absorption and phase contrast modes. The performance of grating-based tomography is demonstrated for freshly explanted male and female urethras in saline solution. The micro-morphology of the urethra is important to understand how the muscles close the urethra to reach continence. As the number of incontinent patients is steadily increasing, the function under static and, more important, under stress conditions has to be uncovered for the realization of artificial urinary sphincters, which needs sophisticated, biologically inspired concepts to become nature analogue.
Laser absorption spectroscopy - Method for monitoring complex trace gas mixtures
Green, B. D.; Steinfeld, J. I.
1976-01-01
A frequency stabilized CO2 laser was used for accurate determinations of the absorption coefficients of various gases in the wavelength region from 9 to 11 microns. The gases investigated were representative of the types of contaminants expected to build up in recycled atmospheres. These absorption coefficients were then used in determining the presence and amount of the gases in prepared mixtures. The effect of interferences on the minimum detectable concentration of the gases was measured. The accuracies of various methods of solution were also evaluated.
A physiological toxicokinetic model for dermal absorption of waterborne pyrene by trout
Energy Technology Data Exchange (ETDEWEB)
Namdari, R.; Law, F.C.P. [Simon Fraser Univ., Burnaby, British Columbia (Canada)
1995-12-31
A physiologically-based toxicokinetic (PB-TK) model was developed to describe the disposition of pyrene in trout following a bolus injection into the dorsal aorta. In the present study, the PB-TK model was adapted for dermal absorption of waterborne pyrene by trout. A skin compartment with transdermal flux described mathematically by the permeability-area-concentration product was added to the PB-TK model to allow prediction of pyrene concentrations in target organs and blood on the basis of exposure concentration at the skin surface. Physiologically relevant parameters e.g., organ volume, blood flow rate, and tissue/blood partitioning coefficient which were derived from the model were similar to those reported in the previous publication. The dermal PB-TK model was validated by exposing the trunk of trout (400--500 g) to stagnant water containing 24 ppm pyrene in a specially designed chamber for 4 hr, 24 hr or 48 hr. The trout were sacrificed at the conclusion of pyrene exposure and the tissues analyzed for unchanged pyrene by HPLC. In separate experiments, trout were implanted with dorsal aorta cannuli before the trunks were exposed to stagnant water containing 24 ppm pyrene in the chamber for 4 hr. At specific time intervals during and after pyrene exposure, blood samples were withdrawn through the cannula and analyzed for pyrene by HPLC. The agreement between simulated and experimentally obtained values shows that this model is an appropriate tool to predict dermal absorption of waterborne pyrene by trout.
Power coefficient anomaly in JOYO
Energy Technology Data Exchange (ETDEWEB)
Yamamoto, H
1980-12-15
Operation of the JOYO experimental fast reactor with the MK-I core has been divided into two phases: (1) 50 MWt power ascension and operation; and (2) 75 MWt power ascension and operation. The 50 MWt power-up tests were conducted in August 1978. In these tests, the measured reactivity loss due to power increases from 15 MWt to 50 MWt was 0.28% ..delta.. K/K, and agreed well with the predicted value of 0.27% ..delta.. K/K. The 75 MWt power ascension tests were conducted in July-August 1979. In the process of the first power increase above 50 MWt to 65 MWt conducted on July 11, 1979, an anomalously large negative power coefficient was observed. The value was about twice the power coefficient values measured in the tests below 50 MW. In order to reproduce the anomaly, the reactor power was decreased and again increased up to the maximum power of 65 MWt. However, the large negative power coefficient was not observed at this time. In the succeeding power increase from 65 MWt to 75 MWt, a similar anomalous power coefficient was again observed. This anomaly disappeared in the subsequent power ascensions to 75 MWt, and the magnitude of the power coefficient gradually decreased with power cycles above the 50 MWt level.
Modification of Einstein A Coefficient in Dissipative Gas Medium
Cao, Chang-Qi; Cao, Hui; Qin, Ke-Cheng
1996-01-01
Spontaneous radiation in dissipative gas medium such as plasmas is investigated by Langevin equations and the modified Weisskopf-Wigner approximation. Since the refractive index of gas medium is expected to be nearly unity, we shall first neglect the medium polarization effect. We show that absorption in plasmas may in certain case modify the Einstein A coefficient significantly and cause a pit in the A coefficient-density curves for relatively low temperature plasmas and also a pit in the A coefficient-temperature curves. In the next, the effect of medium polarization is taken into account in addition. To our surprise, its effect in certain case is quite significant. The dispersive curves show different behaviors in different region of parameters.
Analysis of internal conversion coefficients
International Nuclear Information System (INIS)
Coursol, N.; Gorozhankin, V.M.; Yakushev, E.A.; Briancon, C.; Vylov, Ts.
2000-01-01
An extensive database has been assembled that contains the three most widely used sets of calculated internal conversion coefficients (ICC): [Hager R.S., Seltzer E.C., 1968. Internal conversion tables. K-, L-, M-shell Conversion coefficients for Z=30 to Z=103, Nucl. Data Tables A4, 1-237; Band I.M., Trzhaskovskaya M.B., 1978. Tables of gamma-ray internal conversion coefficients for the K-, L- and M-shells, 10≤Z≤104, Special Report of Leningrad Nuclear Physics Institute; Roesel F., Fries H.M., Alder K., Pauli H.C., 1978. Internal conversion coefficients for all atomic shells, At. Data Nucl. Data Tables 21, 91-289] and also includes new Dirac-Fock calculations [Band I.M. and Trzhaskovskaya M.B., 1993. Internal conversion coefficients for low-energy nuclear transitions, At. Data Nucl. Data Tables 55, 43-61]. This database is linked to a computer program to plot ICCs and their combinations (sums and ratios) as a function of Z and energy, as well as relative deviations of ICC or their combinations for any pair of tabulated data. Examples of these analyses are presented for the K-shell and total ICCs of the gamma-ray standards [Hansen H.H., 1985. Evaluation of K-shell and total internal conversion coefficients for some selected nuclear transitions, Eur. Appl. Res. Rept. Nucl. Sci. Tech. 11.6 (4) 777-816] and for the K-shell and total ICCs of high multipolarity transitions (total, K-, L-, M-shells of E3 and M3 and K-shell of M4). Experimental data sets are also compared with the theoretical values of these specific calculations
Optical absorptions of an exciton in a quantum ring: Effect of the repulsive core
International Nuclear Information System (INIS)
Xie, Wenfang
2013-01-01
We study the optical absorptions of an exciton in a quantum ring. The quantum ring is described as a circular quantum dot with a repulsive core. The advantage of our methodology is that one can investigate the influence of the repulsive core by varying two parameters in the confinement potential. The linear, third-order nonlinear and total optical absorption coefficients have been examined with the change of the confinement potential. The results show that the optical absorptions are strongly affected by the repulsive core. Moreover, the repulsive core can influence the oscillation in the resonant peak of the absorption coefficients.
Algebraic polynomials with random coefficients
Directory of Open Access Journals (Sweden)
K. Farahmand
2002-01-01
Full Text Available This paper provides an asymptotic value for the mathematical expected number of points of inflections of a random polynomial of the form a0(ω+a1(ω(n11/2x+a2(ω(n21/2x2+…an(ω(nn1/2xn when n is large. The coefficients {aj(w}j=0n, w∈Ω are assumed to be a sequence of independent normally distributed random variables with means zero and variance one, each defined on a fixed probability space (A,Ω,Pr. A special case of dependent coefficients is also studied.
International Nuclear Information System (INIS)
Schlueter, W.
1982-01-01
A method has been developed for ascertaining the depth of low-energy photon emitters deposited in wounds. It is based on the determination of the energy-dependent absorption of the emitted photons by the tissue separating source and detector. The method is applicable to counting for low-energy photon-emitting nuclides that can be characterized by more than one quantum energy. Attenuation coefficients were given for lard, beef, and five tissue- equivalent materials. For spectrometry, a planar Ge(Li) detector proved most suitable. (author)
Self-absorption corrections for well-type germanium detectors
International Nuclear Information System (INIS)
Appleby, P.G.; Richardson, N.; Nolan, P.J.
1992-01-01
Corrections for self-absorption are of vital importance to accurate determination by gamma spectrometry of radionuclides such as 210 Pb, 241 Am and 234 Th which emit low energy gamma radiation. A simple theoretical model for determining the necessary corrections for well-type germanium detectors is presented. In this model, self-absorption factors are expressed in terms of the mass attenuation coefficient of the sample and a parameter characterising the well geometry. Experimental measurements of self-absorption are used to evaluate the model and to determine a semi-empirical algorithm for improved estimates of the geometrical parameter. (orig.)
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)
Percutaneous absorption and disposition of Tinopal EMS
International Nuclear Information System (INIS)
Black, T.G.; Moule, R.C.; Philp, J.
1977-01-01
A cotton-substantive, anionic, fluorescent whitening agent manufactured by several suppliers under various trade names e.g. Tinopal EMS, has been synthesized in radioactive form. Intubation of detergent or aqueous solution into rats resulted in little absorption from the intestinal tract as evidenced by low radioactivity in the urine and tissues. Most of the dose was excreted rapidly in the faeces. After parenteral administration to rats, the radioactivity was rapidly excreted in the faeces with small amounts remaining in tissues and organs. There was slight evidence of retention of radioactivity in the kidneys. Very small amounts of Tinopal EMS in detergent were absorbed through rat skin, but only when concentrations greater than those normally used by the consumer, together with occlusion of the skin were employed. Small amounts were absorbed through skin when applied in ethanol. It is concluded that the possibility of systemic toxic effects in man as a result of percutaneous absorption is remote
Potential application of Chinese traditional medicine (CTM) as enhancer for tissue optical clearing
Chen, Wei; Jiang, Jingying; Wang, Ruikang K.; Xu, Kexin
2009-02-01
Many biocompatible hyperosmotic agents such as dimethyl sulfoxide(DMSO) have been used as enhancers for tissue optical clearing technique. However, previous investigations showed that DMSO can induce bradycardia, respiratory problems, and alterations in blood pressure. Also, DMSO could potentially alter the chemical structure, and hence the functional properties, of cell membranes. In this talk, Borneol among natural and nontoxic CTMs was introduced as new enhancer for optical clearing of porcine skin tissue since it has been widely used as new penetration promoter in the field of trandermial drug delivery system(TDDS) and been proved to be effective. In the first, the spectral characteristics of borneol was obtained and analyzed by Fourier Transformation Infrared (FTIR) spectrophotometer. And further experimental studies were performed to probe if borneol is capable of optical clearing of porcine skin tissue in vitro with near infrared spectroscopy, double integrating-spheres system and Inverse Adding-Doubling(IAD) algorithm. Spectral results show that light penetration depth into skin tissue got the increase. Meanwhile, absorption coefficient and scattering coefficient of porcine skin treated by borneol got the decrease during the permeation of Borneol. Therefore, Borneol could be potentially used as enhancer for tissue optical clearing to improve non-invasive light-based diagnostic and imaging techniques while practically optical application and clinical safety are under consideration.
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)
Acoustic absorption behaviour of an open-celled aluminium foam
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...
Irrational "Coefficients" in Renaissance Algebra.
Oaks, Jeffrey A
2017-06-01
Argument From the time of al-Khwārizmī in the ninth century to the beginning of the sixteenth century algebraists did not allow irrational numbers to serve as coefficients. To multiply by x, for instance, the result was expressed as the rhetorical equivalent of . The reason for this practice has to do with the premodern concept of a monomial. The coefficient, or "number," of a term was thought of as how many of that term are present, and not as the scalar multiple that we work with today. Then, in sixteenth-century Europe, a few algebraists began to allow for irrational coefficients in their notation. Christoff Rudolff (1525) was the first to admit them in special cases, and subsequently they appear more liberally in Cardano (1539), Scheubel (1550), Bombelli (1572), and others, though most algebraists continued to ban them. We survey this development by examining the texts that show irrational coefficients and those that argue against them. We show that the debate took place entirely in the conceptual context of premodern, "cossic" algebra, and persisted in the sixteenth century independent of the development of the new algebra of Viète, Decartes, and Fermat. This was a formal innovation violating prevailing concepts that we propose could only be introduced because of the growing autonomy of notation from rhetorical text.
Integer Solutions of Binomial Coefficients
Gilbertson, Nicholas J.
2016-01-01
A good formula is like a good story, rich in description, powerful in communication, and eye-opening to readers. The formula presented in this article for determining the coefficients of the binomial expansion of (x + y)n is one such "good read." The beauty of this formula is in its simplicity--both describing a quantitative situation…
International Nuclear Information System (INIS)
Chinkov, E P; Stepanov, S A; Shtan'ko, V F; Ivanova, T S
2016-01-01
The spectra of stable optical absorption of BaF 2 crystals containing uncontrollable impurities after irradiation with 3 MeV electrons are studied at room temperature. The dependence of the efficiency of stable color accumulation in the region of emerging crossluminescence on the absorption coefficients measured near the fundamental absorption edge in unirradiated crystals of various prehistory is traced. (paper)
Monitoring of tissue optical properties during thermal coagulation of ex vivo tissues.
Nagarajan, Vivek Krishna; Yu, Bing
2016-09-01
Real-time monitoring of tissue status during thermal ablation of tumors is critical to ensure complete destruction of tumor mass, while avoiding tissue charring and excessive damage to normal tissues. Currently, magnetic resonance thermometry (MRT), along with magnetic resonance imaging (MRI), is the most commonly used technique for monitoring and assessing thermal ablation process in soft tissues. MRT/MRI is very expensive, bulky, and often subject to motion artifacts. On the other hand, light propagation within tissue is sensitive to changes in tissue microstructure and physiology which could be used to directly quantify the extent of tissue damage. Furthermore, optical monitoring can be a portable, and cost-effective alternative for monitoring a thermal ablation process. The main objective of this study, is to establish a correlation between changes in tissue optical properties and the status of tissue coagulation/damage during heating of ex vivo tissues. A portable diffuse reflectance spectroscopy system and a side-firing fiber-optic probe were developed to study the absorption (μa (λ)), and reduced scattering coefficients (μ's (λ)) of native and coagulated ex vivo porcine, and chicken breast tissues. In the first experiment, both porcine and chicken breast tissues were heated at discrete temperature points between 24 and 140°C for 2 minutes. Diffuse reflectance spectra (430-630 nm) of native and coagulated tissues were recorded prior to, and post heating. In a second experiment, porcine tissue samples were heated at 70°C and diffuse reflectance spectra were recorded continuously during heating. The μa (λ) and μ's (λ) of the tissues were extracted from the measured diffuse reflectance spectra using an inverse Monte-Carlo model of diffuse reflectance. Tissue heating was stopped when the wavelength-averaged scattering plateaued. The wavelength-averaged optical properties, and , for native porcine tissues (n = 66) at room temperature, were 5.4
Optical gain coefficients of silicon: a theoretical study
Tsai, Chin-Yi
2018-05-01
A theoretical model is presented and an explicit formula is derived for calculating the optical gain coefficients of indirect band-gap semiconductors. This model is based on the second-order time-dependent perturbation theory of quantum mechanics by incorporating all the eight processes of photon/phonon emission and absorption between the band edges of the conduction and valence bands. Numerical calculation results are given for Si. The calculated absorption coefficients agree well with the existing fitting formula of experiment data with two modes of phonons: optical phonons with energy of 57.73 meV and acoustic phonons with energy of 18.27 meV near (but not exactly at) the zone edge of the X-point in the dispersion relation of phonons. These closely match with existing data of 57.5 meV transverse optical (TO) phonons at the X4-point and 18.6 meV transverse acoustic (TA) phonons at the X3-point of the zone edge. The calculated results show that the material optical gain of Si will overcome free-carrier absorption if the energy separation of quasi-Fermi levels between electrons and holes exceeds 1.15 eV.
Neutron resonance absorption theory
International Nuclear Information System (INIS)
Reuss, P.
1991-11-01
After some recalls on the physics of neutron resonance absorption during their slowing down, this paper presents the main features of the theoretical developments performed by the french school of reactor physics: the effective reaction rate method so called Livolant-Jeanpierre theory, the generalizations carried out by the author, and the probability table method [fr
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.)
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
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...
Determination of the optical absorption spectra of thin layers from their photoacoustic spectra
Bychto, Leszek; Maliński, Mirosław; Patryn, Aleksy; Tivanov, Mikhail; Gremenok, Valery
2018-05-01
This paper presents a new method for computations of the optical absorption coefficient spectra from the normalized photoacoustic amplitude spectra of thin semiconductor samples deposited on the optically transparent and thermally thick substrates. This method was tested on CuIn(Te0.7Se0.3)2 thin films. From the normalized photoacoustic amplitude spectra, the optical absorption coefficient spectra were computed with the new formula as also with the numerical iterative method. From these spectra, the value of the energy gap of the thin film material and the type of the optical transitions were determined. From the experimental optical transmission spectra, the optical absorption coefficient spectra were computed too, and compared with the optical absorption coefficient spectra obtained from photoacoustic spectra.
Calibration factor or calibration coefficient?
International Nuclear Information System (INIS)
Meghzifene, A.; Shortt, K.R.
2002-01-01
Full text: The IAEA/WHO network of SSDLs was set up in order to establish links between SSDL members and the international measurement system. At the end of 2001, there were 73 network members in 63 Member States. The SSDL network members provide calibration services to end-users at the national or regional level. The results of the calibrations are summarized in a document called calibration report or calibration certificate. The IAEA has been using the term calibration certificate and will continue using the same terminology. The most important information in a calibration certificate is a list of calibration factors and their related uncertainties that apply to the calibrated instrument for the well-defined irradiation and ambient conditions. The IAEA has recently decided to change the term calibration factor to calibration coefficient, to be fully in line with ISO [ISO 31-0], which recommends the use of the term coefficient when it links two quantities A and B (equation 1) that have different dimensions. The term factor should only be used for k when it is used to link the terms A and B that have the same dimensions A=k.B. However, in a typical calibration, an ion chamber is calibrated in terms of a physical quantity such as air kerma, dose to water, ambient dose equivalent, etc. If the chamber is calibrated together with its electrometer, then the calibration refers to the physical quantity to be measured per electrometer unit reading. In this case, the terms referred have different dimensions. The adoption by the Agency of the term coefficient to express the results of calibrations is consistent with the 'International vocabulary of basic and general terms in metrology' prepared jointly by the BIPM, IEC, ISO, OIML and other organizations. The BIPM has changed from factor to coefficient. The authors believe that this is more than just a matter of semantics and recommend that the SSDL network members adopt this change in terminology. (author)
Extinction Coefficient of Gold Nanostars
de Puig, Helena; Tam, Justina O.; Yen, Chun-Wan; Gehrke, Lee; Hamad-Schifferli, Kimberly
2015-01-01
Gold nanostars (NStars) are highly attractive for biological applications due to their surface chemistry, facile synthesis and optical properties. Here, we synthesize NStars in HEPES buffer at different HEPES/Au ratios, producing NStars of different sizes and shapes, and therefore varying optical properties. We measure the extinction coefficient of the synthesized NStars at their maximum surface plasmon resonances (SPR), which range from 5.7 × 108 to 26.8 × 108 M−1cm−1. Measured values correl...
On the absorption of a sound in helium 2
International Nuclear Information System (INIS)
Matveev, Yu.A.
1977-01-01
A theory is developed which describes the propagation of high frequency sound in helium 2 at low temperatures (T 15 atm.) pressures when the phonon energy spectrum becomes stable. The absorption and sound dispersion coefficients under these conditions are calculated. The dependence of the velocity of second sound on frequency is determined. The resonance properties of the solution obtained are discussed
Experiments on a vapour absorption heat transformer
Energy Technology Data Exchange (ETDEWEB)
George, J M; Murthy, S S [Indian Inst. of Tech., Madras (India). Dept. of Mechanical Engineering
1993-03-01
Tests were conducted on a 3 kW heating capacity R21-DMF vapour absorption heat transformer to study the influence of operating temperature on its performance. Heat source temperature and condensing temperature were varied in the ranges 50-75[sup o]C and 20-40[sup o]C, respectively. Heat delivery temperatures up to 85[sup o]C and temperature lifts up to 20[sup o]C were achieved. Actual coefficients of performance (COPs) ranged from 0.2 to 0.35, whereas exergetic efficiencies of 0.3-0.4 could be obtained. (Author)
Refraction and absorption of microwaves in wood
International Nuclear Information System (INIS)
Ziherl, Saša; Bajc, Jurij; Čepič, Mojca
2013-01-01
A demonstration experiment for physics students showing the dependence of the refractive index and absorption coefficient of wood on the direction of microwaves is presented. Wood and microwaves enable study of anisotropic properties, which are typically found in crystals. Wood is used as the persuasive representative of uniaxial anisotropic materials due to its visible structure and its consequent anisotropic properties. Wood can be cut in a general direction and wooden plates a few centimetres thick with well-defined fibre orientation are easily prepared. Microwaves are used because wood is transparent for microwaves and their centimetre-scale wavelength is comparable to the wood structure. (paper)
Form of multicomponent Fickian diffusion coefficients matrix
International Nuclear Information System (INIS)
Wambui Mutoru, J.; Firoozabadi, Abbas
2011-01-01
Highlights: → Irreversible thermodynamics establishes form of multicomponent diffusion coefficients. → Phenomenological coefficients and thermodynamic factors affect sign of diffusion coefficients. → Negative diagonal elements of diffusion coefficients matrix can occur in non-ideal mixtures. → Eigenvalues of the matrix of Fickian diffusion coefficients may not be all real. - Abstract: The form of multicomponent Fickian diffusion coefficients matrix in thermodynamically stable mixtures is established based on the form of phenomenological coefficients and thermodynamic factors. While phenomenological coefficients form a symmetric positive definite matrix, the determinant of thermodynamic factors matrix is positive. As a result, the Fickian diffusion coefficients matrix has a positive determinant, but its elements - including diagonal elements - can be negative. Comprehensive survey of reported diffusion coefficients data for ternary and quaternary mixtures, confirms that invariably the determinant of the Fickian diffusion coefficients matrix is positive.
Wilson, Robert H.; Vishwanath, Karthik; Mycek, Mary-Ann
2009-02-01
Monte Carlo (MC) simulations are considered the "gold standard" for mathematical description of photon transport in tissue, but they can require large computation times. Therefore, it is important to develop simple and efficient methods for accelerating MC simulations, especially when a large "library" of related simulations is needed. A semi-analytical method involving MC simulations and a path-integral (PI) based scaling technique generated time-resolved reflectance curves from layered tissue models. First, a zero-absorption MC simulation was run for a tissue model with fixed scattering properties in each layer. Then, a closed-form expression for the average classical path of a photon in tissue was used to determine the percentage of time that the photon spent in each layer, to create a weighted Beer-Lambert factor to scale the time-resolved reflectance of the simulated zero-absorption tissue model. This method is a unique alternative to other scaling techniques in that it does not require the path length or number of collisions of each photon to be stored during the initial simulation. Effects of various layer thicknesses and absorption and scattering coefficients on the accuracy of the method will be discussed.
Absorption and radiation of nonminimally coupled scalar field from charged BTZ black hole
Huang, Lu; Chen, Juhua; Wang, Yongjiu
2018-06-01
In this paper we investigate the absorption and radiation of nonminimally coupled scalar field from the charged BTZ black hole. We find the analytical expressions for the reflection coefficient, the absorption cross section and the decay rate in strong coupling case. We find that the reflection coefficient is directly governed by Hawking temperature TH, scalar wave frequency ω , Bekenstein-Hawking entropy S_{BH}, angular momentum m and coupling constant ξ.
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
[Spectral absorption properties of the water constituents in the estuary of Zhujiang River].
Wang, Shan-shan; Wang, Yong-bo; Fu, Qing-hua; Yin, Bin; Li, Yun-mei
2014-12-01
Spectral absorption properties of the water constituents is the main factor affecting the light field under the surface of the water and the spectrum above the surface of the water. Thus, the study is useful for understanding of the water spectral property and the remote reversing of water quality parameters. Absorption properties of total suspended particles, non-algal particles, phytoplankton and CDOM were analyzed using the 30 samples collected in July 2013 in the estuary of Zhujiang River. The results indicated that: (1) the non-algal particles absorption dominated the absorption of the total suspended particles; (2) the absorption coefficient of the non-algal particles, which mainly came from the terrigenous deposits, decreased exponentially from short to long wavelength. In addition, the average value and spatial variation of the slope S(d) were higher than those in inland case- II waters; (3) the absorption coefficient of phytoplankton in 440 nm showed a better polynomial relationship with chlorophyll a concentration, while the absorption coefficient of phytoplankton in 675 nm linearly related with the chlorophyll a concentration. Moreover, the influence of accessory pigments on phytoplankton absorption coefficient mainly existed in the range of short wavelength, and Chlorophyll a was the main influencing factor for phytoplankton absorption in long wavelength. The specific absorption coefficient of phytoplankton decreased the power exponentially with the increase of the chlorophyll a concentration; (4) CDOM mainly came from the terrigenous sources and its spectral curve had an absorption shoulder between 250-290 nm. Thus, a piecewise S(g) fitting function could effectively express CDOM absorption properties, i.e., M value and S(g) value in period A (240-260 nm) showed a strong positive correlation. The M value was low, and the humic acid had a high proportion in CDOM; (5) the non-algal particles absorption dominated the total absorption in the estuary of
In vitro double-integrating-sphere optical properties of tissues between 630 and 1064 nm
Beek, J. F.; Blokland, P.; Posthumus, P.; Aalders, M.; Pickering, J. W.; Sterenborg, H. J. C. M.; van Gemert, M. J. C.
1997-11-01
The optical properties (absorption and scattering coefficients and the scattering anisotropy factor) were measured in vitro for cartilage, liver, lung, muscle, myocardium, skin, and tumour (colon adenocarcinoma CC 531) at 630, 632.8, 790, 850 and 1064 nm. Rabbits, rats, piglets, goats, and dogs were used to obtain the tissues. A double-integrating-sphere setup with an intervening sample was used to determine the reflectance, and the diffuse and collimated transmittances of the sample. The inverse adding - doubling algorithm was used to determine the optical properties from the measurements. The overall results were comparable to those available in the literature, although only limited data are available at 790 - 850 nm. The results were reproducible for a specific sample at a specific wavelength. However, when comparing the results of different samples of the same tissue or different lasers with approximately the same wavelength (e.g. argon dye laser at 630 nm and HeNe laser at 632.8 nm) variations are large. We believe these variations in optical properties should be explained by biological variations of the tissues. In conclusion, we report on an extensive set of in vitro absorption and scattering properties of tissues measured with the same equipment and software, and by the same group. Although the accuracy of the method requires further improvement, it is highly likely that the other existing data in the literature have a similar level of accuracy.
Absorption dynamics and delay time in complex potentials
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.
Iwamoto, Misako; Honda, Norihiro; Ishii, Katsunori; Awazu, Kunio
2017-07-01
Spectroscopic setup for measuring anisotropy factor g spectrum of biological tissues was constructed. g of chicken liver tissue was lower than chicken breast tissue. High absorption of hemoglobin can have an influence on g spectrum.
Reduction in the absorption and retention of strontium in rats
Energy Technology Data Exchange (ETDEWEB)
Slat, B; Kostial, K; Harrison, G E
1971-12-01
Rats were fed a stock diet supplemented with calcium phosphate and sodium alginate, both separately and simultaneously, over a period of 4-5 months. Observations were made at intervals on the growth rate and on visual and histological abnormalities in some body tissues. No toxic effects were observed. The absorption and skeletal retention of calcium for rats on the combined supplements remained almost unchanged but the absorption and retention of strontium was reduced 7-fold.
Study of transport coefficients of nanodiamond nanofluids
Pryazhnikov, M. I.; Minakov, A. V.; Guzei, D. V.
2017-09-01
Experimental data on the thermal conductivity coefficient and viscosity coefficient of nanodiamond nanofluids are presented. Distilled water and ethylene glycol were used as the base fluid. Dependences of transport coefficients on concentration are obtained. It was shown that the thermal conductivity coefficient increases with increasing nanodiamonds concentration. It was shown that base fluids properties and nanodiamonds concentration affect on the rheology of nanofluids.
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.
Attenuation of the gamma rays in tissues
International Nuclear Information System (INIS)
Arcos P, A.; Rodriguez N, S.; Pinedo S, A.; Amador V, P.; Chacon R, A.; Vega C, H.R.
2005-01-01
The mass and lineal attenuation coefficient and of hepatic tissue, muscular, osseous and of brain before gamma rays of 10 -3 to 10 5 MeV were calculated. For the case of the osseous tissue the calculation was made for the cartilage, the cortical tissue and the bone marrow. During the calculations the elementary composition of the tissues of human origin was used. The calculations include by separate the Photoelectric effect, the Compton scattering and the Pair production, as well as the total. For to establish a comparison with the attenuation capacities, the coefficients of the water, the aluminum and the lead also were calculated. The study was complemented measuring the attenuation coefficient of hepatic tissue of bovine before gamma rays of 0.662 MeV of a source of 137 Cs. The measurement was made through of an experiment of photons transmission through samples frozen of hepatic tissue and with a Geiger-Mueller detector. (Author)
Influence of solvent absorption on the migration of Irganox 1076 from LDPE
Helmroth, I.E.; Dekker, M.; Hankemeier, T.
2002-01-01
The effect of solvent absorption on additive migration was studied by relating the diffusion coefficient (D) of Irganox 1076 to the maximum solvent absorption of different solvents in low-density polyethylene (LDPE) film. Solvents tested were ethanol, isopropanol, isooctane, ethylacetate,
Electronic absorption spectrum of copper-doped magnesium potassium phosphate hexahydrate
Rao, S. N.; Sivaprasad, P.; Reddy, Y. P.; Rao, P. S.
1992-04-01
The optical absorption and EPR spectra of magnesium potassium phosphate hexahydrate (MPPH) doped with copper ions are recorded both at room and liquid nitrogen temperatures. The spectrum is characteristic of Cu2+ in tetragonal symmetry. The spin-Hamiltonian parameters and molecular orbital coefficients are evaluated. A correlation between EPR and optical absorption studies is drawn.
Absorption properties of water-in-oil emulsions in the low THz frequency range
DEFF Research Database (Denmark)
Møller, Uffe; Folkenberg, Jacob Riis; Jepsen, Peter Uhd
We use transmission THz spectroscopy to investigate the absorption properties of water-in-oil emulsions with water content varying in the 0-20% range, relevant for a range of food products. We find that at low frequencies the effective absorption coefficient of the emulsion is suppressed compared...... to bulk water....
Optical absorption and Faraday rotation in spin doped Cd1-xHgxSe : Mn crystals
Savchuk, AI; Paranchich, SY; Paranchich, LD; Romanyuk, OS; Andriychuk, MD; Nikitin, PI; Tomlinson, RD; Hill, AE; Pilkington, RD
1998-01-01
Optical absorption spectra and the Faraday effect in crystals of Cd1-xHgxSe : Mn have been studied. The studied samples have been characterized abrupt absorption edge and transparency region with high transmission coefficient. The measured values of Verdet constant were considerably larger than in
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)
International Nuclear Information System (INIS)
Dincklage, R.D. von.
1984-01-01
The absorption meter consists of a radiation source, a trough for the absorbing liquid and a detector. It is characterized by the fact that there is a foil between the detector and the trough, made of a material whose binding energy of the K electrons is a little greater than the energy of the photons emitted by the radiation source. The source of radiation and foil are replaceable. (orig./HP) [de
International Nuclear Information System (INIS)
Rubio, B.; Gelletly, W.
2007-01-01
The problem of determining the distribution of beta decay strength (B(GT)) as a function of excitation energy in the daughter nucleus is discussed. Total Absorption Spectroscopy is shown to provide a way of determining the B(GT) precisely. A brief history of such measurements and a discussion of the advantages and disadvantages of this technique, is followed by examples of two recent studies using the technique. (authors)
Evaluation of Rock Joint Coefficients
Audy, Ondřej; Ficker, Tomáš
2017-10-01
A computer method for evaluation of rock joint coefficients is described and several applications are presented. The method is based on two absolute numerical indicators that are formed by means of the Fourier replicas of rock joint profiles. The first indicator quantifies the vertical depth of profiles and the second indicator classifies wavy character of profiles. The absolute indicators have replaced the formerly used relative indicators that showed some artificial behavior in some cases. This contribution is focused on practical computations testing the functionality of the newly introduced indicators.
Hui, Xiaoying; Lamel, Sonia; Qiao, Peter; Maibach, Howard I
2013-03-01
Since the advent of World War II, governments and laboratories have made a concerted effort to improve prophylactic and therapeutic interventions counteracting cutaneously directed chemical warfare agents (CWA), and by inference, common industrial and consumer dermatotoxicants. In vitro percutaneous penetration assays, first utilized by Tregear in the 1940s and presently in various modifications, have been fundamental to this effort. Percutaneous penetration, often considered a simple one-step diffusion process, consists of at least 15 steps. The first part of this review covers the initial steps related to absorption and excretion kinetics, vehicle characteristics, and tissue disposition. Importantly, the partitioning behavior and stratum corneum (SC) diffusion by a wide physicochemical array of compounds shows that many compounds have similar diffusion coefficients determining their percutaneous absorption in vivo. After accounting for anatomical SC variation, the penetration flux value of a substance depends mainly on its SC/vehicle partition coefficient. Additionally, the SC acts as a 'reservoir' for topically applied molecules and application of tape stripping has been found to quantify the chemical remaining in the SC which can predict total molecular penetration in vivo. Decontamination is of particular concern and even expediting standard washing procedures after dermal chemical exposure often fails to remove chemicals. This overview summarizes knowledge of percutaneous penetration extending insights into the complexities of penetration, decontamination and potential newer assays that may be of practical importance. Copyright © 2012 John Wiley & Sons, Ltd.
Correlation coefficients in neutron β-decay
International Nuclear Information System (INIS)
Byrne, J.
1978-01-01
The various angular and polarisation coefficients in neutron decay are the principal sources of information on the β-interaction. Measurements of the electron-neutrino angular correlation coefficient (a), the neutron-spin-electron-momentum correlation coefficient (A), the neutron-spin-neutrino-momentum correlation coefficient (B), and the triple correlation coefficient D and time-reversal invariance are reviewed and the results discussed. (U.K.)
Recombination coefficients in extrinsic n-InSb
International Nuclear Information System (INIS)
Schneider, W.; Groh, H.; Huebner, K.
1976-01-01
The bulk recombination coefficients for linear recombination via recombination centers as well as for direct recombination have been determined measuring the conductivity decay after two-photon absorption with a CO 2 laser. The Suhl effect was applied to measure the surface recombination velocity. The corresponding literature is discussed and compared with our results. We conclude that two different kinds of recombination centers are possible in n-InSb, with energy levels (0.1-0.12)eV above the valence band, or (0.14-0.2)eV respectively. (orig.) [de
Age-dependent dose coefficients for tritium in Asian populations
International Nuclear Information System (INIS)
Trivedi, A.
1999-10-01
The International Commission on Radiological Protection (ICRP) Publications 56 (1989) and 67 (1993) have prescribed the biokinetic models and age-dependent dose coefficients for tritiated water and organically bound tritium. The dose coefficients are computed from values selected to specify the anatomical, morphological and physiological characteristics of a three-month-old, one-year-old, five-year-old, 10-year-old, 15-year-old and adult (Reference Man) Caucasian living in North America and Western Europe. However, values for Reference Man and other age groups are not directly applicable to Asians, because of differences in race, custom, dietary habits and climatic conditions. An Asian Man model, including five age groups, has been proposed by Tanaka and Kawamura (1996, 1998) for use in internal dosimetry. The basic concept of the ICRP Reference Man and the system describing body composition in ICRP Publication 23 (1975) were used. Reference values for Asians were given for the body weight and height, the mass of soft tissue, the mass of body water and the daily fluid balance, and are used to compute the dose coefficients for tritium. The age-dependent dose coefficients for Asians for tritiated water intakes are smaller by 20 to 30% of the currently prescribed values (Trivedi, 1998). The reduction in the dose coefficient values is caused by the increased daily fluid balance among Asians. The dose coefficient for tritiated water is 1.4 x 10 -11 Sv Bq -1 for Asian Man compared to 2.0 x 10 -11 Sv Bq -1 for Reference Man. The dose coefficients for organically bound tritium are only marginally different from those of the ICRP values. The dose coefficient for organically bound tritium for Asian Man is 4.0 x 10 -11 Sv Bq -11 compared to 4.6 x 10 -11 Sv Bq -1 for Reference Man. (author)
Age-dependent dose coefficients for tritium in Asian populations
Energy Technology Data Exchange (ETDEWEB)
Trivedi, A
1999-10-01
The International Commission on Radiological Protection (ICRP) Publications 56 (1989) and 67 (1993) have prescribed the biokinetic models and age-dependent dose coefficients for tritiated water and organically bound tritium. The dose coefficients are computed from values selected to specify the anatomical, morphological and physiological characteristics of a three-month-old, one-year-old, five-year-old, 10-year-old, 15-year-old and adult (Reference Man) Caucasian living in North America and Western Europe. However, values for Reference Man and other age groups are not directly applicable to Asians, because of differences in race, custom, dietary habits and climatic conditions. An Asian Man model, including five age groups, has been proposed by Tanaka and Kawamura (1996, 1998) for use in internal dosimetry. The basic concept of the ICRP Reference Man and the system describing body composition in ICRP Publication 23 (1975) were used. Reference values for Asians were given for the body weight and height, the mass of soft tissue, the mass of body water and the daily fluid balance, and are used to compute the dose coefficients for tritium. The age-dependent dose coefficients for Asians for tritiated water intakes are smaller by 20 to 30% of the currently prescribed values (Trivedi, 1998). The reduction in the dose coefficient values is caused by the increased daily fluid balance among Asians. The dose coefficient for tritiated water is 1.4 x 10{sup -11} Sv Bq{sup -1} for Asian Man compared to 2.0 x 10{sup -11} Sv Bq{sup -1} for Reference Man. The dose coefficients for organically bound tritium are only marginally different from those of the ICRP values. The dose coefficient for organically bound tritium for Asian Man is 4.0 x 10{sup -11} Sv Bq{sup -11} compared to 4.6 x 10{sup -11} Sv Bq{sup -1} for Reference Man. (author)
Fisher, John P; Bronzino, Joseph D
2007-01-01
Increasingly viewed as the future of medicine, the field of tissue engineering is still in its infancy. As evidenced in both the scientific and popular press, there exists considerable excitement surrounding the strategy of regenerative medicine. To achieve its highest potential, a series of technological advances must be made. Putting the numerous breakthroughs made in this field into a broad context, Tissue Engineering disseminates current thinking on the development of engineered tissues. Divided into three sections, the book covers the fundamentals of tissue engineering, enabling technologies, and tissue engineering applications. It examines the properties of stem cells, primary cells, growth factors, and extracellular matrix as well as their impact on the development of tissue engineered devices. Contributions focus on those strategies typically incorporated into tissue engineered devices or utilized in their development, including scaffolds, nanocomposites, bioreactors, drug delivery systems, and gene t...
Exploring the origin of high optical absorption in conjugated polymers
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.
Exploring the origin of high optical absorption in conjugated polymers
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.
International Nuclear Information System (INIS)
Horvatic, Vlasta; Veza, Damir; Niemax, Kay; Vadla, Cedomil
2008-01-01
A simple and accurate way of determining atom number densities in dense rubidium vapors is presented. The method relies on the experimental finding that the reduced absorption coefficients of the Rb triplet satellite bands between 740 nm and 750 nm and the triplet diffuse band between 600 nm and 610 nm are not temperature dependent in the range between 600 K and 800 K. Therefore, the absolute values of the reduced absorption coefficients of these molecular bands can provide accurate information about atomic number density of the vapor. The rubidium absorption spectrum was measured by spatially resolved white-light absorption in overheated rubidium vapor generated in a heat pipe oven. The absolute values for the reduced absorption coefficients of the triplet bands were determined at lower vapor densities, by using an accurate expression for the reduced absorption coefficient in the quasistatic wing of the Rb D1 line, and measured triplet satellite bands to the resonance wing optical depth ratio. These triplet satellite band data were used to calibrate in absolute scale the reduced absorption coefficients of the triplet diffuse band at higher temperatures. The obtained values for the reduced absorption coefficient of these Rb molecular features can be used for accurate determination of rubidium atomic number densities in the range from about 5 x 10 16 cm -3 to 1 x 10 18 cm -3
Analysis of a solar powered absorption system
International Nuclear Information System (INIS)
Said, S.A.M.; El-Shaarawi, M.A.I.; Siddiqui, M.U.
2015-01-01
Highlights: • Conventional absorption system modified to increase COP. • Results indicated increase of 10% in COP due to dephlegmator heat recovery. • Results indicated increase of 8% in COP due to refrigerant storage unit. • Results indicated increase of 18% in COP due to combined effect of modifications. • Simulation results indicated a very good agreement with the measured results. - Abstract: Today, fossil fuel is the primary extensively used source of energy. However, its negative impact on the environment have forced the energy research continuity to seriously consider renewable sources of energy. Solar energy, in particular, has been the main focus in this regard because it is a source of clean energy and naturally available. This study presents the design and analysis of a solar powered absorption refrigeration system modified to increase its coefficient of performance (COP). The modifications include recovering of waste heat from a dephlegmator and utilization of a refrigerant storage unit. The simulation results indicate an increase of 10% in the COP of the conventional design using dephlegmator heat recovery and an increase of 8% in the COP of the conventional design due to the use of a refrigerant storage. The analysis for the combined effect of modifications indicates an increase of 18% in the COP compared to conventional design. Calculated values of coefficient of performance indicate a very good agreement with the ones obtained based on measurement
Vishwanath, Karthik; Chang, Kevin; Klein, Daniel; Deng, Yu Feng; Chang, Vivide; Phelps, Janelle E; Ramanujam, Nimmi
2011-02-01
Steady-state diffuse reflection spectroscopy is a well-studied optical technique that can provide a noninvasive and quantitative method for characterizing the absorption and scattering properties of biological tissues. Here, we compare three fiber-based diffuse reflection spectroscopy systems that were assembled to create a light-weight, portable, and robust optical spectrometer that could be easily translated for repeated and reliable use in mobile settings. The three systems were built using a broadband light source and a compact, commercially available spectrograph. We tested two different light sources and two spectrographs (manufactured by two different vendors). The assembled systems were characterized by their signal-to-noise ratios, the source-intensity drifts, and detector linearity. We quantified the performance of these instruments in extracting optical properties from diffuse reflectance spectra in tissue-mimicking liquid phantoms with well-controlled optical absorption and scattering coefficients. We show that all assembled systems were able to extract the optical absorption and scattering properties with errors less than 10%, while providing greater than ten-fold decrease in footprint and cost (relative to a previously well-characterized and widely used commercial system). Finally, we demonstrate the use of these small systems to measure optical biomarkers in vivo in a small-animal model cancer therapy study. We show that optical measurements from the simple portable system provide estimates of tumor oxygen saturation similar to those detected using the commercial system in murine tumor models of head and neck cancer.
Gamma ray attenuation coefficient measurement for neutron-absorbent materials
Energy Technology Data Exchange (ETDEWEB)
Jalali, Majid [Isfahan Nuclear Science and Technology Research Institute (NSTRT), Reactor and Accelerators Research and Development School, Atomic Energy Organization (Iran, Islamic Republic of)], E-mail: m_jalali@entc.org.ir; Mohammadi, Ali [Faculty of Science, Department of Physics, University of Kashan, Km. 6, Ravand Road, Kashan (Iran, Islamic Republic of)
2008-05-15
The compounds Na{sub 2}B{sub 4}O{sub 7}, H{sub 3}BO{sub 3}, CdCl{sub 2} and NaCl and their solutions attenuate gamma rays in addition to neutron absorption. These compounds are widely used in the shielding of neutron sources, reactor control and neutron converters. Mass attenuation coefficients of gamma related to the four compounds aforementioned, in energies 662, 778.9, 867.38, 964.1, 1085.9, 1173, 1212.9, 1299.1,1332 and 1408 keV, have been determined by the {gamma} rays transmission method in a good geometry setup; also, these coefficients were calculated by MCNP code. A comparison between experiments, simulations and Xcom code has shown that the study has potential application for determining the attenuation coefficient of various compound materials. Experiment and computation show that H{sub 3}BO{sub 3} with the lowest average Z has the highest gamma ray attenuation coefficient among the aforementioned compounds.
International Nuclear Information System (INIS)
Shiroki, Ken-ichi; Kuwano, Yasuhiko
1978-01-01
Effective Nd segregation coefficient in the Nd:YAG (Nd-doped Y 3 Al 5 O 12 ) crystal growth by pulling method was determined precisely over 0 -- 1.3 atom% Nd concentration range at a 0.6 mm hr -1 growth rate. Two Nd:YAG crystals (-- 20 g) were grown from a large melt (-- 1 kg). Neodymium concentrations in the crystals and residual melts were estimated by fluorescent X-ray analysis, and a value of 0.21 was obtained as the effective segregation coefficient. Next, the optical absorption coefficient of Nd:YAG crystal at 5889 A absorption peak was measured in order to analyze a small specimen for Nd by optical absorption measurements. The optical absorption coefficient of 0.97 mm -1 .atom% -1 was determined in this way. The Nd concentrations, calculated by the segregation coefficient, agreed well with those obtained by optical absorption measurements at 5889 A for six successively grown Nd:YAG crystals. Therefore, the obtained segregation coefficient, 0.21, was confirmed as a reliable value for the Nd:YAG crystal growth by the pulling method. (auth.)
Effect of UV laser irradiation on tissue
International Nuclear Information System (INIS)
Nakayama, Takeyoshi; Kubo, Uichi
1992-01-01
Laser-tissue interactions have been investigated through Electron Probe Micro Analysis (EPMA), UV-visible optical absorption and Fourier Transform Infrared Spectroscopy (FTIR). Three excimer lasers, ArF, KrF and XeCl, were used to irradiate tissue; cow thighbone and gelatin thin film. Features of UV laser irradiation are described. (author)
Directory of Open Access Journals (Sweden)
Graziela Custodio Balassa
2010-07-01
Full Text Available The study sought to evaluate the potential of the aquatic macrophytePontederia parviflora Alexander in the absorption of copper (Cu and possible variations in its tissues after 21 days of exposure to this metal. The concentration of Cu was analyzed in the solution and in the vegetal tissues (stem, root and leaves. The experiment was set up in triplicates with weekly measurements of pH, temperature and DO. The results indicated that P. parviflora reduced 96% of Cu in the solution and the root was the vegetal tissue, which accumulated more Cu. Values of pH, DO and temperature were in accordance with the metabolic activities of the plants. In the anatomic analyses, dark spots were identified in the vascular bundles and in the epidermis of the aerial parts, highlighting the variation resulting from the presence of this substance. However, these variations were not sufficient to damage the development of the individuals. P. parviflora showed high capacity of extraction and storage of the metal, being a good alternative to aquatic environments with high concentrations of Cu. O estudo avaliou o potencial da macrófita aquática Pontederia parviflora Alexander na absorção de cobre (Cu e possíveis alterações nos tecidos, após 21 dias de exposição. O teor do metal foi analisado na solução e nos tecidos vegetais (caule, raiz e folhas. O experimento foi montado em triplicatas com medidas semanais dopH, temperatura e OD. Os resultados mostraram que P. parviflora reduziu 96% do Cu na solução e a porção vegetal que acumulou mais o metal foi a radicular. O pH, OD e temperatura apresentaram valores condizentes com as atividades metabólicas das plantas. Nas análises anatômicas, foram identificadas manchas escuras nos feixes vasculares e na epiderme das partes aéreas, evidenciando a alteração provocada pela presença da substância. No entanto essas alterações não foram suficientes para prejudicar o desenvolvimento dos indivíduos. P
Extinction Coefficient of Gold Nanostars.
de Puig, Helena; Tam, Justina O; Yen, Chun-Wan; Gehrke, Lee; Hamad-Schifferli, Kimberly
2015-07-30
Gold nanostars (NStars) are highly attractive for biological applications due to their surface chemistry, facile synthesis and optical properties. Here, we synthesize NStars in HEPES buffer at different HEPES/Au ratios, producing NStars of different sizes and shapes, and therefore varying optical properties. We measure the extinction coefficient of the synthesized NStars at their maximum surface plasmon resonances (SPR), which range from 5.7 × 10 8 to 26.8 × 10 8 M -1 cm -1 . Measured values correlate with those obtained from theoretical models of the NStars using the discrete dipole approximation (DDA), which we use to simulate the extinction spectra of the nanostars. Finally, because NStars are typically used in biological applications, we conjugate DNA and antibodies to the NStars and calculate the footprint of the bound biomolecules.
Kerr scattering coefficients via isomonodromy
Energy Technology Data Exchange (ETDEWEB)
Cunha, Bruno Carneiro da [Departamento de Física, Universidade Federal de Pernambuco,50670-901, Recife, Pernambuco (Brazil); Novaes, Fábio [International Institute of Physics, Federal University of Rio Grande do Norte,Av. Odilon Gomes de Lima 1722, Capim Macio, Natal-RN 59078-400 (Brazil)
2015-11-23
We study the scattering of a massless scalar field in a generic Kerr background. Using a particular gauge choice based on the current conservation of the radial equation, we give a generic formula for the scattering coefficient in terms of the composite monodromy parameter σ between the inner and the outer horizons. Using the isomonodromy flow, we calculate σ exactly in terms of the Painlevé V τ-function. We also show that the eigenvalue problem for the angular equation (spheroidal harmonics) can be calculated using the same techniques. We use recent developments relating the Painlevé V τ-function to Liouville irregular conformal blocks to claim that this scattering problem is solved in the combinatorial sense, with known expressions for the τ-function near the critical points.
Optical absorption in dendrimers
International Nuclear Information System (INIS)
Supritz, C.; Engelmann, A.; Reineker, P.
2004-01-01
Dendrimers are highly branched molecules, which are expected to be useful, for example, as efficient artificial light harvesting systems in nano-technological applications. There are two different classes of dendrimers: compact dendrimers with constant distance between neighboring branching points throughout the macromolecule and extended dendrimers, where this distance increases from the system periphery to the center. We investigate the linear absorption spectra of these dendrimer types using the Frenkel exciton concept. The electron-phonon interaction is taken into account by introducing a heat bath that interacts with the exciton in a stochastic manner
Rapidly variable relatvistic absorption
Parker, M.; Pinto, C.; Fabian, A.; Lohfink, A.; Buisson, D.; Alston, W.; Jiang, J.
2017-10-01
I will present results from the 1.5Ms XMM-Newton observing campaign on the most X-ray variable AGN, IRAS 13224-3809. We find a series of nine absorption lines with a velocity of 0.24c from an ultra-fast outflow. For the first time, we are able to see extremely rapid variability of the UFO features, and can link this to the X-ray variability from the inner accretion disk. We find a clear flux dependence of the outflow features, suggesting that the wind is ionized by increasing X-ray emission.
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.
Chemical effect on total mass attenuation coefficients of V, Cr, Mn, Co and Ni
International Nuclear Information System (INIS)
Soeguet, Oe.; Colak, S.; Bueyuekkasap, E.; Kuecuekoender, A.
2002-01-01
Detailed interpretation of data obtained from X-ray transmission measurements usually depends on the assumption that the contribution of each element is additive. This assumption yields the mixture rule for X-ray attenuation coefficients which is valid if molecular and chemical effects are negligible. Total mass attenuation coefficients of V, Cr, Mn, Co and Ni in various their compounds was measured. Absorption corrections were carried on data for ligands in the compounds. It was found that V, Cr, Mn, Co and Ni had different total mass attenuation coefficients in the different compounds. Results were compared with theoretical values of HUBBELL and SELTZER. (author)
Coefficient of restitution and plastic strain for impact of elements welded with micro-jet cooling
Directory of Open Access Journals (Sweden)
Damian HADRYŚ
2014-06-01
Full Text Available The main purpose of investigations is the qualification how post-accident repair of model car body parts influence on the value of coefficient of restitution. Evaluation of impact energy absorption by model car body parts repaired with MIG welding (with and without micro-jet cooling was carried out. The results of investigations present that the value of coefficient of restitution changes with speed of impact. Coefficient of restitution is bigger for elements welded with micro-jet cooling than for element welded with ordinary method. This could have influence on passive safety of vehicle.