Sensitivity of coefficients for converting entrance surface dose and kerma-area product to effective dose and energy imparted to the patient

NASA Astrophysics Data System (ADS)

Wise, K. N.; Sandborg, M.; Persliden, J.; Alm Carlsson, G.

1999-08-01

We investigate the sensitivity of the conversions from entrance surface dose (ESD) or kerma-area product (KAP) to effective dose (E) or to energy imparted to the patient () to the likely variations in tube potential, field size, patient size and sex which occur in clinical work. As part of a factorial design study for chest and lumbar spine examinations, the tube potentials were varied to be ±10% of the typical values for the examinations while field sizes and the positions of the field centres were varied to be representative of values drawn from measurements on patient images. Variation over sex and patient size was based on anthropomorphic phantoms representing males and females of ages 15 years (small adult) and 21 years (reference adult). All the conversion coefficients were estimated using a mathematical phantom programmed with the Monte Carlo code EGS4 for all factor combinations and analysed statistically to derive factor effects. In general, the factors studied behaved independently in the sense that interaction of the physical factors generally gave no more than a 5% variation in a conversion coefficient. Taken together, variation of patient size, sex, field size and field position can lead to significant variation of E/KAP by up to a factor of 2, of E/ESD by up to a factor of 3, of /KAP by a factor of 1.3 and of /ESD by up to a factor of 2. While KAP is preferred to determine , the results show no strong preference of KAP over ESD in determining E. The mean absorbed dose in the patient obtained by dividing (determined using KAP) by the patient's mass was found to be the most robust measure of E.

Effective Dose of Positioning Scans for Five CBCT Devices

DTIC Science & Technology

2016-05-25

CBCT. Journal of Dental Research , Dental Clinics , Dental Prospects 2014;8(2):107-10. 26. Kim D, Rashsuren O, Kim E. Conversion coefficients for the... International Journal of Oral & Maxillofacial Implants 2014;29:55-77. 10. Brooks SL. Radiation doses of common dental radiographic examinations: A review...dose was measured with metal–oxide–semiconductor field-effect transistor (MOSFET) dosimeters for five CBCT devices in a postgraduate dental clinic

Technical Note: exploring the limit for the conversion of energy-subtracted CT number to electron density for high-atomic-number materials.

PubMed

Saito, Masatoshi; Tsukihara, Masayoshi

2014-07-01

For accurate tissue inhomogeneity correction in radiotherapy treatment planning, the authors had previously proposed a novel conversion of the energy-subtracted CT number to an electron density (ΔHU-ρe conversion), which provides a single linear relationship between ΔHU and ρe over a wide ρe range. The purpose of this study is to address the limitations of the conversion method with respect to atomic number (Z) by elucidating the role of partial photon interactions in the ΔHU-ρe conversion process. The authors performed numerical analyses of the ΔHU-ρe conversion for 105 human body tissues, as listed in ICRU Report 46, and elementary substances with Z = 1-40. Total and partial attenuation coefficients for these materials were calculated using the XCOM photon cross section database. The effective x-ray energies used to calculate the attenuation were chosen to imitate a dual-source CT scanner operated at 80-140 kV/Sn under well-calibrated and poorly calibrated conditions. The accuracy of the resultant calibrated electron density,[Formula: see text], for the ICRU-46 body tissues fully satisfied the IPEM-81 tolerance levels in radiotherapy treatment planning. If a criterion of [Formula: see text]ρe - 1 is assumed to be within ± 2%, the predicted upper limit of Z applicable for the ΔHU-ρe conversion under the well-calibrated condition is Z = 27. In the case of the poorly calibrated condition, the upper limit of Z is approximately 16. The deviation from the ΔHU-ρe linearity for higher Z substances is mainly caused by the anomalous variation in the photoelectric-absorption component. Compensation among the three partial components of the photon interactions provides for sufficient linearity of the ΔHU-ρe conversion to be applicable for most human tissues even for poorly conditioned scans in which there exists a large variation of effective x-ray energies owing to beam-hardening effects arising from the mismatch between the sizes of the object and the calibration phantom.

Naturalistic conversation improves daytime motorway driving performance under a benzodiazepine: a randomised, crossover, double-blind, placebo-controlled study.

PubMed

Moták, Ladislav; Bayssac, Laëtitia; Taillard, Jacques; Sagaspe, Patricia; Huet, Nathalie; Terrier, Patrice; Philip, Pierre; Daurat, Agnès

2014-06-01

The adverse effects of benzodiazepines on driving are widely recognised. The aims of this study were both to determine the impact of naturalistic conversation on the driving ability of drivers under a benzodiazepine, and to measure the accuracy of drivers' assessments of the joint effects of the benzodiazepine and conversation. Sixteen healthy male participants (29.69 ± 3.30 years) underwent a randomised, crossover, double-blind, placebo-controlled study with the benzodiazepine lorazepam (2mg). They drove 200 km (125 miles) on a motorway in the morning. We measured two driving ability-related variables (i.e., lane-keeping performance), and collected a set of self-assessed variables (i.e., self-assessment of driving performance) during two 10-min sequences of interest (no conversation vs. conversation). An analysis of variance revealed an interaction whereby lane-keeping performance under lorazepam was worse in the no-conversation condition than in the conversation condition. No such difference was detected under placebo. Pearson's correlation coefficients revealed that self-assessments were (i) not at all predictive of lane-keeping when performed before the drive, but (ii) moderately predictive of lane-keeping performance when performed during or after the drive. We conclude that conversation with a passenger may contribute to safer lane-keeping when driving under a benzodiazepine. Moreover, a degree of awareness may be attained after some experience of driving under the influence of this type of medication. Copyright © 2014 Elsevier Ltd. All rights reserved.

DOSE COEFFICIENTS FOR LIVER CHEMOEMBOLISATION PROCEDURES USING MONTE CARLO CODE.

PubMed

Karavasilis, E; Dimitriadis, A; Gonis, H; Pappas, P; Georgiou, E; Yakoumakis, E

2016-12-01

The aim of the present study is the estimation of radiation burden during liver chemoembolisation procedures. Organ dose and effective dose conversion factors, normalised to dose-area product (DAP), were estimated for chemoembolisation procedures using a Monte Carlo transport code in conjunction with an adult mathematical phantom. Exposure data from 32 patients were used to determine the exposure projections for the simulations. Equivalent organ (H T ) and effective (E) doses were estimated using individual DAP values. The organs receiving the highest amount of doses during these exams were lumbar spine, liver and kidneys. The mean effective dose conversion factor was 1.4 Sv Gy -1 m -2 Dose conversion factors can be useful for patient-specific radiation burden during chemoembolisation procedures. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Measurements of ion-molecule reactions of He plus, H plus, HeH plus with H sub 2 and D sub 2

NASA Technical Reports Server (NTRS)

Johnsen, R.; Biondi, M. A.

1974-01-01

A drift tube mass spectrometer apparatus has been used to determine the rate coefficient, energy dependence and product ions of the reaction He(+) +H2. The total rate coefficient at 300 K is 1.1 plus or minus 0.1) 10 to minus 13th power cu cm/sec. The reaction proceeds principally by dissociative charge transfer to produce H(+), with the small remainder going by charge transfer to produce H2(+) and by atom rearrangement to produce HeH(+). The rate coefficient increases slowly with increasing ion mean energy, reaching a value of 2.8 x ten to the minus 13th power cu cm sec at 0.18 eV. The corresponding reaction with deuterium, He(+) + D2, exhibits a value (5 plus or minus 1) x 10 to the minus 14th cu cm/sec at 300K. The reaction rates for conversion of H(+) and HeH(+) to H3(+) on collisions with H2 molecules are found to agree well with results of previous investigations.

Identification of significant E0 strength in the 22+ → 21+ transitions of 58,60,62Ni

NASA Astrophysics Data System (ADS)

Evitts, L. J.; Garnsworthy, A. B.; Kibédi, T.; Smallcombe, J.; Reed, M. W.; Brown, B. A.; Stuchbery, A. E.; Lane, G. J.; Eriksen, T. K.; Akber, A.; Alshahrani, B.; de Vries, M.; Gerathy, M. S. M.; Holt, J. D.; Lee, B. Q.; McCormick, B. P.; Mitchell, A. J.; Moukaddam, M.; Mukhopadhyay, S.; Palalani, N.; Palazzo, T.; Peters, E. E.; Ramirez, A. P. D.; Stroberg, S. R.; Tornyi, T.; Yates, S. W.

2018-04-01

The E0 transition strength in the 22+ →21 + transitions of 58,60,62Ni have been determined for the first time following a series of measurements at the Australian National University (ANU) and the University of Kentucky (UK). The CAESAR Compton-suppressed HPGe array and the Super-e solenoid at ANU were used to measure the δ (E 2 / M 1) mixing ratio and internal conversion coefficient of each transition following inelastic proton scattering. Level half-lives, δ (E 2 / M 1) mixing ratios and γ-ray branching ratios were measured at UK following inelastic neutron scattering. The new spectroscopic information was used to determine the E0 strengths. These are the first 2+ →2+E0 transition strengths measured in nuclei with spherical ground states and the E0 component is found to be unexpectedly large; in fact, these are amongst the largest E0 transition strengths in medium and heavy nuclei reported to date.

"Spin-dependent" \\varvec{μ → e} conversion on light nuclei

NASA Astrophysics Data System (ADS)

Davidson, Sacha; Kuno, Yoshitaka; Saporta, Albert

2018-02-01

The experimental sensitivity to μ → e conversion will improve by four or more orders of magnitude in coming years, making it interesting to consider the "spin-dependent" (SD) contribution to the rate. This process does not benefit from the atomic-number-squared enhancement of the spin-independent (SI) contribution, but probes different operators. We give details of our recent estimate of the spin-dependent rate, expressed as a function of operator coefficients at the experimental scale. Then we explore the prospects for distinguishing coefficients or models by using different targets, both in an EFT perspective, where a geometric representation of different targets as vectors in coefficient space is introduced, and also in three leptoquark models. It is found that comparing the rate on isotopes with and without spin could allow one to detect spin-dependent coefficients that are at least a factor of few larger than the spin-independent ones. Distinguishing among the axial, tensor and pseudoscalar operators that induce the SD rate would require calculating the nuclear matrix elements for the second two. Comparing the SD rate on nuclei with an odd proton vs. odd neutron could allow one to distinguish operators involving u quarks from those involving d quarks; this is interesting because the distinction is difficult to make for SI operators.

Realization of a mW-level 10.7-eV (λ = 115.6 nm) laser by cascaded third harmonic generation of a Yb:fiber CPA laser at 1-MHz.

PubMed

Zhao, Zhigang; Kobayashi, Yohei

2017-06-12

We demonstrate a 10.7-eV (λ = 115.6 nm) laser with mW levels of average power and a 1-MHz repetition rate, which was driven by the third harmonic radiation (THG), at 347 nm, of an Yb:fiber chirped pulse amplifier (CPA) laser. The 347 nm ultraviolet radiation was obtained by frequency conversion of the high power output of a 1-MHz Yb:fiber CPA, using beta barium borate (BBO) nonlinear crystals. The frequency converted output was focused down into a gas cell filled with a mixture of Ar and Xe, and was subjected to a second THG frequency conversion. The generated 10.7-eV laser was separated from the fundamental beam using a LiF prism and no further separation from other harmonic waves was required. The highest measured output power was ~80 μW, which corresponded to an average power of ~1.25 mW inside the gas cell when the transmission coefficients of the LiF optics were taken into account. The corresponding conversion efficiency from 347 nm down to 115.6 nm was ~2.5 × 10 -4 .

Gold and CuS as multifunctional theranostics platform for imaging and therapy (Conference Presentation)

NASA Astrophysics Data System (ADS)

Zhu, Junjie

2017-02-01

Localized surface plasmon resonances arising from the free carriers in copper-deficient copper chalcogenides nanocrystals (Cu2-xE, E=S,Se) enables them with high extinction coefficient in the near-infrared range, which was superior for photothermal related purpose. Although Cu2-xE nanocrystals with different compositions (0< x≪1) all possess NIR absorption, their extinction coefficients were significantly different due to their distinct valence band free carrier concentration. Herein, by optimizing the synthetic conditions, we were able to obtain pure covellite phase CuS nanoparticles with maximized free carrier concentration (x=1), which provides extremely high mass extinction coefficient (up to 60 Lg-1cm-1 at 980 nm and 32.4 Lg-1cm-1 at 800 nm). To the best of our knowledge, these values was maximal among all inorganic nanomaterials. High quality Cu2-xSe can also be obtained with a similar approach. In order to introduce CuS nanocrystals for biomedical applications, we further transferred these nanocrystals into aqueous solution with an amphiphilic polymer and colvalently linked with beta-cyclodextrin. Using host-guest interaction, adamantine-modified RGD peptide can be further anchored on the nanoparticles for the recognition of integrin-positive cancer cells. Together with the high extinction coefficient and outstand photothermal conversion efficiency (determined to be higher than 40%), these CuS nanocrystals were applied for photothermal therapy of cancer cells and photoacoustic imaging. In addition, anticancer drug doxorubicin can also be loading onto the nanoparticles through either hydrophobic or electrostatic interaction for chemotherapy.

Improved ferroelectric, piezoelectric and electrostrictive properties of dense BaTiO{sub 3} ceramic

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baraskar, Bharat G.; Kakade, S. G.; Kambale, R. C., E-mail: rckambale@gmail.com

2016-05-23

The ferroelectric, piezoelectric and electrostrictive properties of BaTiO{sub 3} (BT) dense ceramic synthesized by solid-state reaction were investigated. X-ray diffraction study confirmed tetragonal crystal structure having c/a ~1.0144. The dense microstructure was evidenced from morphological studies with an average grain size ~7.8 µm. Temperature dependent dielectric measurement showed the maximum values of dielectric constant, ε{sub r} = 5617 at Curie temperature, T{sub c} = 125 °C. The saturation and remnant polarization, P{sub sat.} = 24.13 µC/cm{sup 2} and P{sub r} =10.42 µC/cm{sup 2} achieved respectively for the first time with lower coercive field of E{sub c}=2.047 kV/cm. The polarization currentmore » density-electric field measurement exhibits the peaking characteristics, confirms the saturation state of polarization for BT. The strain-electric field measurements revealed the “sprout” shape nature instead of typical “butterfly loop”. This shows the excellent converse piezoelectric response with remnant strain ~ 0.212% and converse piezoelectric constant d*{sub 33} ~376.35 pm/V. The intrinsic electrostrictive coefficient was deduced from the variation of strain with polarization with electrostrictive coefficient Q{sub 33}~ 0.03493m{sup 4}/C{sup 2}.« less

Ortho-para-H2 conversion by hydrogen exchange: comparison of theory and experiment.

PubMed

Lique, François; Honvault, Pascal; Faure, Alexandre

2012-10-21

We report fully-quantum time-independent calculations of cross sections and rate coefficients for the collisional (de)excitation of H(2) by H. Our calculations are based on the H(3) global potential energy surface of Mielke et al. [J. Chem. Phys. 116, 4142 (2002)]. The reactive hydrogen exchange channels are taken into account. We show that the ortho-para and para-ortho conversion of H(2) are significant processes at temperatures above ~300 K and for the last process we provide the first comparison with available experimental rate coefficients between 300 and 444 K. The good agreement between theory and experiment is a new illustration of our detailed understanding of the simplest chemical reaction. The importance of the ortho-para-H(2) conversion by hydrogen exchange in astrophysics is discussed.

Room-temperature giant magneto-mechanical-electric cross-coupling in Si-integrated PbZr0.52Ti0.48O3/Ni50Mn35In15 multiferroic heterostructures

NASA Astrophysics Data System (ADS)

Singh, Kirandeep; Kaur, Davinder

2017-04-01

The current study reports the strong magnetoelectric coupling (M-E) in silicon (Si)-integrated ferromagnetic shape memory alloy-based PZT/Ni-Mn-In thin-film multiferroic heterostructure. The strain-mediated nature of converse M-E coupling is reflected from the butterfly-shaped normalized magnetization (M/M s) versus electric field plots. The direct M-E properties of the heterostructure were measured with a frequency of AC magnetic field, bias magnetic field, as well as with temperature. A maximum direct M-E coupling in the bilayered thin-film multiferroic heterostructures occurred at resonance frequencies around the first-order structural transitional temperature of the bottom Ni-Mn-In layer. It was observed that the measuring temperature remarkably affects the direct M-E characteristic of the heterostructure. A large direct ME effect and converse ME effect coefficient α DME  ~  894 mV cm-1.Oe and α CME ~ 2.7  ×  10-5 s m-1, respectively, were achieved in the bilayer at room temperature. The mechanism of direct as well as converse M-E effects in the thin-film multiferroic heterostructures is discussed. The electrically driven angular dependence of normalized magnetization (M/M s) reveals the twofold symmetric magnetic anisotropy of the heterostructure, with the drastic shifting of the magnetic hard axis at E  >  E c (coercivity of PZT).

Equivalent circuit model of converse magnetoelectric effect for the tri-layer magnetoelectric laminates with thermal and stress loadings

NASA Astrophysics Data System (ADS)

Zhou, Hao-Miao; Li, Meng-Han; Liu, Hui; Cui, Xiao-Le

2015-12-01

For the converse magnetoelectric coupling effect of the piezoelectric/magnetostrictive/piezoelectric tri-layer symmetric magnetoelectric laminates, based on the nonlinear thermo-magneto-mechanical constitutive equations of the giant magnetostrictive materials and the thermo-electro-mechanical constitutive equations of the piezoelectric materials, according to Newton's second law and the magnetic circuit theorem, an equivalent circuit is established. Then an expression of the converse magnetoelectric coefficient describing nonlinear thermo-magneto-electro-mechanical coupling is established. The curve of the nonlinear converse magnetoelectric coefficient versus the bias magnetic field, is predicted effectively by the expression, and the predictions are in good agreement with the experimental result both qualitatively and quantitatively. Furthermore, the model can predict the complex influences of the bias magnetic field, the stress and the ambient temperature on the converse magnetoelectric coefficient. It can be found from these predictions that the converse magnetoelectric coefficient decreases with the increasing temperature and increases with the increasing tensile stress. Under the common effect of the ambient temperature and the stress, it is also found that the converse magnetoelectric coefficient changes sharply with the ambient temperature when the tensile stress is applied on the laminates, but it has a good stability of temperature when a large compressive stress is applied. Therefore, this work contributes to the researches on the giant converse magnetoelectric coefficient and the designs of magnetoelectric devices based on the converse magnetoelectric coupling.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Dae Jung; Lee, Dong-Hun; Kim, Kihong

We study theoretically the linear mode conversion between electromagnetic waves and Langmuir waves in warm, stratified, and unmagnetized plasmas, using a numerically precise calculation based on the invariant imbedding method. We verify that the principle of reciprocity for the forward and backward mode conversion coefficients holds precisely regardless of temperature. We also find that the temperature dependence of the mode conversion coefficient is substantially stronger than that previously reported. Depending on the wave frequency and the incident angle, the mode conversion coefficient is found to increase or decrease with the increase of temperature.

Error free all optical wavelength conversion in highly nonlinear As-Se chalcogenide glass fiber.

PubMed

Ta'eed, Vahid G; Fu, Libin; Pelusi, Mark; Rochette, Martin; Littler, Ian C; Moss, David J; Eggleton, Benjamin J

2006-10-30

We present the first demonstration of all optical wavelength conversion in chalcogenide glass fiber including system penalty measurements at 10 Gb/s. Our device is based on As2Se3 chalcogenide glass fiber which has the highest Kerr nonlinearity (n(2)) of any fiber to date for which either advanced all optical signal processing functions or system penalty measurements have been demonstrated. We achieve wavelength conversion via cross phase modulation over a 10 nm wavelength range near 1550 nm with 7 ps pulses at 2.1 W peak pump power in 1 meter of fiber, achieving only 1.4 dB excess system penalty. Analysis and comparison of the fundamental fiber parameters, including nonlinear coefficient, two-photon absorption coefficient and dispersion parameter with other nonlinear glasses shows that As(2)Se(3) based devices show considerable promise for radically integrated nonlinear signal processing devices.

Dose conversion coefficients for monoenergetic electrons incident on a realistic human eye model with different lens cell populations

NASA Astrophysics Data System (ADS)

Nogueira, P.; Zankl, M.; Schlattl, H.; Vaz, P.

2011-11-01

The radiation-induced posterior subcapsular cataract has long been generally accepted to be a deterministic effect that does not occur at doses below a threshold of at least 2 Gy. Recent epidemiological studies indicate that the threshold for cataract induction may be much lower or that there may be no threshold at all. A thorough study of this subject requires more accurate dose estimates for the eye lens than those available in ICRP Publication 74. Eye lens absorbed dose per unit fluence conversion coefficients for electron irradiation were calculated using a geometrical model of the eye that takes into account different cell populations of the lens epithelium, together with the MCNPX Monte Carlo radiation transport code package. For the cell population most sensitive to ionizing radiation—the germinative cells—absorbed dose per unit fluence conversion coefficients were determined that are up to a factor of 4.8 higher than the mean eye lens absorbed dose conversion coefficients for electron energies below 2 MeV. Comparison of the results with previously published values for a slightly different eye model showed generally good agreement for all electron energies. Finally, the influence of individual anatomical variability was quantified by positioning the lens at various depths below the cornea. A depth difference of 2 mm between the shallowest and the deepest location of the germinative zone can lead to a difference between the resulting absorbed doses of up to nearly a factor of 5000 for electron energy of 0.7 MeV.

Dose conversion coefficients for monoenergetic electrons incident on a realistic human eye model with different lens cell populations.

PubMed

Nogueira, P; Zankl, M; Schlattl, H; Vaz, P

2011-11-07

The radiation-induced posterior subcapsular cataract has long been generally accepted to be a deterministic effect that does not occur at doses below a threshold of at least 2 Gy. Recent epidemiological studies indicate that the threshold for cataract induction may be much lower or that there may be no threshold at all. A thorough study of this subject requires more accurate dose estimates for the eye lens than those available in ICRP Publication 74. Eye lens absorbed dose per unit fluence conversion coefficients for electron irradiation were calculated using a geometrical model of the eye that takes into account different cell populations of the lens epithelium, together with the MCNPX Monte Carlo radiation transport code package. For the cell population most sensitive to ionizing radiation-the germinative cells-absorbed dose per unit fluence conversion coefficients were determined that are up to a factor of 4.8 higher than the mean eye lens absorbed dose conversion coefficients for electron energies below 2 MeV. Comparison of the results with previously published values for a slightly different eye model showed generally good agreement for all electron energies. Finally, the influence of individual anatomical variability was quantified by positioning the lens at various depths below the cornea. A depth difference of 2 mm between the shallowest and the deepest location of the germinative zone can lead to a difference between the resulting absorbed doses of up to nearly a factor of 5000 for electron energy of 0.7 MeV.

Fluence-to-absorbed-dose conversion coefficients for neutron beams from 0.001 eV to 100 GeV calculated for a set of pregnant female and fetus models

NASA Astrophysics Data System (ADS)

Taranenko, Valery; Xu, X. George

2008-03-01

Protection of fetuses against external neutron exposure is an important task. This paper reports a set of absorbed dose conversion coefficients for fetal and maternal organs for external neutron beams using the RPI-P pregnant female models and the MCNPX code. The newly developed pregnant female models represent an adult female with a fetus including its brain and skeleton at the end of each trimester. The organ masses were adjusted to match the reference values within 1%. For the 3 mm cubic voxel size, the models consist of 10-15 million voxels for 35 organs. External monoenergetic neutron beams of six standard configurations (AP, PA, LLAT, RLAT, ROT and ISO) and source energies 0.001 eV-100 GeV were considered. The results are compared with previous data that are based on simplified anatomical models. The differences in dose depend on source geometry, energy and gestation periods: from 20% up to 140% for the whole fetus, and up to 100% for the fetal brain. Anatomical differences are primarily responsible for the discrepancies in the organ doses. For the first time, the dependence of mother organ doses upon anatomical changes during pregnancy was studied. A maximum of 220% increase in dose was observed for the placenta in the nine months model compared to three months, whereas dose to the pancreas, small and large intestines decreases by 60% for the AP source for the same models. Tabulated dose conversion coefficients for the fetus and 27 maternal organs are provided.

Growth of Cu2ZnSnS4(CZTS) by Pulsed Laser Deposition for Thin film Photovoltaic Absorber Material

NASA Astrophysics Data System (ADS)

Nandur, Abhishek; White, Bruce

2014-03-01

CZTS (Cu2ZnSnS4) has become the subject of intense interest because it is an ideal candidate absorber material for thin-film solar cells with an optimal band gap (1.5 eV), high absorption coefficient (104 cm-1) and abundant elemental components. Pulsed Laser Deposition (PLD) provides excellent control over film composition since thin films are deposited under high vacuum with excellent stoichiometry transfer from the target. CZTS thin films were deposited using PLD from a stoichiometrically close CZTS target (Cu2.6Zn1.1Sn0.7S3.44). The effects of laser energy fluence and substrate temperature and post-deposition sulfur annealing on the surface morphology, composition and optical absorption have been investigated. Optimal CZTS thin films exhibited a band gap of 1.54 eV with an absorption coefficient of 4x104cm-1. A solar cell utilizing PLD grown CZTS with the structure SLG/Mo/CZTS/CdS/ZnO/ITO showed a conversion efficiency of 5.85% with Voc = 376 mV, Jsc = 38.9 mA/cm2 and Fill Factor, FF = 0.40.

Low-Temperature Atomic Layer Deposition of CuSbS2 for Thin-Film Photovoltaics.

PubMed

Riha, Shannon C; Koegel, Alexandra A; Emery, Jonathan D; Pellin, Michael J; Martinson, Alex B F

2017-02-08

Copper antimony sulfide (CuSbS 2 ) has been gaining traction as an earth-abundant absorber for thin-film photovoltaics given its near ideal band gap for solar energy conversion (∼1.5 eV), large absorption coefficient (>10 4 cm -1 ), and elemental abundance. Through careful in situ analysis of the deposition conditions, a low-temperature route to CuSbS 2 thin films via atomic layer deposition has been developed. After a short (15 min) postprocess anneal at 225 °C, the ALD-grown CuSbS 2 films were crystalline with micron-sized grains, exhibited a band gap of 1.6 eV and an absorption coefficient >10 4 cm -1 , as well as a hole concentration of 10 15 cm -3 . Finally, the ALD-grown CuSbS 2 films were paired with ALD-grown TiO 2 to form a photovoltaic device. This photovoltaic device architecture represents one of a very limited number of Cd-free CuSbS 2 PV device stacks reported to date, and it is the first to demonstrate an open-circuit voltage on par with CuSbS 2 /CdS heterojunction PV devices. While far from optimized, this work demonstrates the potential for ALD-grown CuSbS 2 thin films in environmentally benign photovoltaics.

Phase matching in RT KTP crystal for down-conversion into the THz range

NASA Astrophysics Data System (ADS)

Huang, J.-G.; Huang, Z.-M.; Nikolaev, N. A.; Mamrashev, A. A.; Antsygin, V. D.; Potaturkin, O. I.; Meshalkin, A. B.; Kaplun, A. B.; Lanskii, G. V.; Andreev, Yu M.; Ezhov, D. M.; Svetlichnyi, V. A.

2018-07-01

Dispersion of refractive index and absorption coefficients in flux-grown high-resistivity KTiOPO4 crystals between 0.2–2.5 THz are verified at room temperature by a THz-TDS. Measured dispersion components n x , n y and n z are approximated for the first time in the form of Sellmeier equations. Phase matching for down-conversion into the THz range under a visible and near IR pump is found possible only in the principle plane by and types of three-wave interactions. Low frequency THz generation is favorable due to the low absorption coefficient down to 0.2 cm‑1, below 0.5 THz.

Self-Consistent Conversion of a Viscous Fluid to Particles and Heavy-Ion Physics Applications

NASA Astrophysics Data System (ADS)

Wolff, Zack J.

The most widely used theoretical framework to model the early stages of a heavy-ion collision is viscous hydrodynamics. Comparing hydrodynamic simulations to heavy-ion data inevitably requires the conversion of the fluid to particles. This conversion, typically done in the Cooper-Frye formalism, is ambiguous for viscous fluids. In this thesis work, self-consistent phase space corrections are calculated by solving the linearized Boltzmann equation. These species-dependent solutions are contrasted with those obtained using the ad-hoc ''democratic Grad'' ansatz typically employed in the literature in which coefficients are independent of particle dynamics. Solutions are calculated analytically for a massless gas and numerically for the general case of a hadron resonance gas. For example, it is found that for a gas of massless particles interacting via isotropic, energy-independent 2 → 2 scatterings, the shear viscous corrections variationally prefer a momentum dependence close to p3/2 rather than the quadratic dependence assumed in the Grad ansatz. The self-consistent phase space distributions are then used to calculate transverse momentum spectra and differential flow coefficients, v n(pT), to study the effects on heavy-ion identified particle observables. Using additive quark model cross sections, it is found that proton flow coefficients are higher than those for pions at moderately high pT in Pb + Pb collisions at LHC, especially for the coefficients v 4 and v6.

Technical Note: Relation between dual-energy subtraction of CT images for electron density calibration and virtual monochromatic imaging.

PubMed

Saito, Masatoshi

2015-07-01

For accurate tissue inhomogeneity correction in radiotherapy treatment planning, the author previously proposed a simple conversion of the energy-subtracted computed tomography (CT) number to an electron density (ΔHU-ρe conversion), which provides a single linear relationship between ΔHU and ρe over a wide ρe range. The purpose of the present study was to reveal the relation between the ΔHU image for ρe calibration and a virtually monochromatic CT image by performing numerical analyses based on the basis material decomposition in dual-energy CT. The author determined the weighting factor, α0, of the ΔHU-ρe conversion through numerical analyses of the International Commission on Radiation Units and Measurements Report-46 human body tissues using their attenuation coefficients and given ρe values. Another weighting factor, α(E), for synthesizing a virtual monochromatic CT image from high- and low-kV CT images, was also calculated in the energy range of 0.03 < E < 5 MeV, assuming that cortical bone and water were the basis materials. The mass attenuation coefficients for these materials were obtained using the xcom photon cross sections database. The effective x-ray energies used to calculate the attenuation were chosen to imitate a dual-source CT scanner operated at 80-140 and 100-140 kV/Sn. The determined α0 values were 0.455 for 80-140 kV/Sn and 0.743 for 100-140 kV/Sn. These values coincided almost perfectly with the respective maximal points of the calculated α(E) curves located at approximately 1 MeV, in which the photon-matter interaction in human body tissues is exclusively the incoherent (Compton) scattering. The ΔHU image could be regarded substantially as a CT image acquired with monoenergetic 1-MeV photons, which provides a linear relationship between CT numbers and electron densities.

Absorbed dose in target cell nuclei and dose conversion coefficient of radon progeny in the human lung.

PubMed

Nikezic, D; Lau, B M F; Stevanovic, N; Yu, K N

2006-01-01

To calculate the absorbed dose in the human lung due to inhaled radon progeny, ICRP focussed on the layers containing the target cells, i.e., the basal and secretory cells. Such an approach did not consider details of the sensitive cells in the layers. The present work uses the microdosimetric approach and determines the absorbed alpha-particle energy in non-spherical nuclei of target cells (basal and secretory cells). The absorbed energy for alpha particles emitted by radon progeny in the human respiratory tract was calculated in basal- and secretory-cell nuclei, assuming conical and ellipsoidal forms for these cells. Distributions of specific energy for different combinations of alpha-particle sources, energies and targets are calculated and shown. The dose conversion coefficient for radon progeny is reduced for about 2mSv/WLM when conical and ellipsoidal cell nuclei are considered instead of the layers. While changes in the geometry of secretory-cell nuclei do not have significant effects on their absorbed dose, changes from spherical to conical basal-cell nuclei have significantly reduced their absorbed dose from approximately 4 to approximately 3mGy/WLM. This is expected because basal cells are situated close to the end of the range of 6MeV alpha particles. This also underlines the significance of better and more precise information on targets in the T-B tree. A further change in the dose conversion coefficient can be achieved if a different weighting scheme is adopted for the doses for the cells. The results demonstrate the necessity for better information on the target cells for more accurate dosimetry for radon progeny.

Nationwide conversion to generic tacrolimus in pediatric kidney transplant recipients.

PubMed

Naicker, Derisha; Reed, Peter W; Ronaldson, Jane; Kara, Tonya; Wong, William; Prestidge, Chanel

2017-11-01

Bioequivalence between Tacrolimus Prograf® and generic tacrolimus formulations has been demonstrated in adult populations, however clinical experience and safety data regarding generic tacrolimus in pediatric transplant recipients is limited. This study aimed to evaluate conversion from Tacrolimus Prograf® to Sandoz® in pediatric renal transplant recipients nationwide. The primary outcome was a change in mean trough tacrolimus concentration. Additionally, changes in tacrolimus intra-patient coefficient of variation (CoV), allograft function, requirement for dose adjustments, and episodes of biopsy-proven rejection were evaluated. Retrospective cohort study in 37 pediatric renal transplant recipients who switched to Tacrolimus Sandoz®. Each patient had three pre-conversion tacrolimus trough and creatinine concentrations within the 4 months prior and three post-conversion concentrations on day 3, 10, and the next subsequent level. Mean pre- and post-conversion tacrolimus trough concentrations and glomerular filtration rate (eGFR) were calculated. Tacrolimus concentration, CoV, and creatinine differences were compared by paired t test. Thirty-seven patients (41% females, age 3-18 years) were included. Average intra-patient difference in trough tacrolimus concentration was 0.05μg/l (95% CI -0.37 to 0.47). Average intra-patient difference in eGFR was -1.20 ml/min/1.73 2 (95% CI -3.53 to 1.13). Three patients had acute rejection during 12 months post-conversion compared to none during 12 months pre-conversion. Pediatric renal transplant recipients can be converted from Tacrolimus Prograf® to Sandoz® with negligible change in trough concentration, dose adjustments, or immediate allograft function. Of concern was the number of acute rejection episodes, however non-adherence contributed to at least one episode and this difference was determined clinically and statistically not significant.

Organ dose conversion coefficients for voxel models of the reference male and female from idealized photon exposures

NASA Astrophysics Data System (ADS)

Schlattl, H.; Zankl, M.; Petoussi-Henss, N.

2007-04-01

A new series of organ equivalent dose conversion coefficients for whole body external photon exposure is presented for a standardized couple of human voxel models, called Rex and Regina. Irradiations from broad parallel beams in antero-posterior, postero-anterior, left- and right-side lateral directions as well as from a 360° rotational source have been performed numerically by the Monte Carlo transport code EGSnrc. Dose conversion coefficients from an isotropically distributed source were computed, too. The voxel models Rex and Regina originating from real patient CT data comply in body and organ dimensions with the currently valid reference values given by the International Commission on Radiological Protection (ICRP) for the average Caucasian man and woman, respectively. While the equivalent dose conversion coefficients of many organs are in quite good agreement with the reference values of ICRP Publication 74, for some organs and certain geometries the discrepancies amount to 30% or more. Differences between the sexes are of the same order with mostly higher dose conversion coefficients in the smaller female model. However, much smaller deviations from the ICRP values are observed for the resulting effective dose conversion coefficients. With the still valid definition for the effective dose (ICRP Publication 60), the greatest change appears in lateral exposures with a decrease in the new models of at most 9%. However, when the modified definition of the effective dose as suggested by an ICRP draft is applied, the largest deviation from the current reference values is obtained in postero-anterior geometry with a reduction of the effective dose conversion coefficient by at most 12%.

SU-D-209-06: Study On the Dose Conversion Coefficients in Pediatric Radiography with the Development of Children Voxel Phantoms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Q; Shanghai General Hospital, Shanghai, Shanghai; Zhuo, W

Purpose: Conversion coefficients of organ dose normalized to entrance skin dose (ESD) are widely used to evaluate the organ doses directly using ESD without time-consuming dose measurement, this work aims to investigate the dose conversion coefficients in pediatric chest and abdomen radiography with the development of 5 years and 10 years old children voxel phantoms. Methods: After segmentation of organs and tissues from CT slice images of ATOM tissue-equivalent phantoms, a 5-year-old and a 10-year-old children computational voxel phantoms were developed for Monte Carlo simulation. The organ doses and the entrance skin dose for pediatric chest postero-anterior projection and abdominalmore » antero-posterior projection were simulated at the same time, and then the organ dose conversion coefficients were calculated.To verify the simulated results, dose measurement was carried out with ATOM tissue-equivalent phantoms for 5 year chest radiography. Results: Simulated results and experimental results matched very well with each other, the result differences of all the organs covered in radiation field were below 16% for 5-year-old child in chest projection. I showed that the conversion coefficients of organs covered in the radiation field were much larger than organs out of the field for all the study cases, for example, the conversion coefficients of stomach, liver intestines, and pancreas are larger for abdomen radiography while conversion coefficients of lungs are larger for chest radiography. Conclusion: The voxel children phantoms were helpful to evaluate the radiation doses more accurately and efficiently. Radiation field was the essential factor that affects the organ dose, use reasonably small field should be encouraged for radiation protection. This work was supported by the National Natural Science Foundation of China(11475047)« less

Effective doses and organ doses in the MIRD-5 phantom exposed to monoenergetic 0.1 MeV to 200 MeV electrons in the LAT direction.

PubMed

Katagiri, M; Hikoji, M; Kitaichi, M; Aoki, Y; Sawamura, S

2001-01-01

Organ doses and effective doses were calculated using the EGS-4 Monte Carlo simulation code and a MIRD-5 mathematical human phantom placed in a vacuum. For broad right and left lateral beams of monoenergetic (0.1-200 MeV) electrons, conversion coefficients from the incident fluence to organ dose, to effective dose, and to effective dose equivalent were obtained. There were no clear differences between the conversion coefficients in the case of left-lateral (LLAT) and right-lateral (RLAT) irradiation. Therefore, when investigating lateral geometries for electron exposure, it is not necessary to evaluate both directions independently. In general, conversion coefficients for lateral irradiation (LAT) were smaller than those for AP and PA. The difference between the AP and PA conversion coefficients and LAT became smaller with increasing incident energy; at 200 MeV the conversion coefficients were almost independent of the irradiation geometry. The agreement between the results of the present study and those of other studies was acceptable within the statistical uncertainties.

Personal Dose Equivalent Conversion Coefficients For Photons To 1 GEV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Veinot, K. G.; Hertel, N. E.

2010-09-27

The personal dose equivalent, H{sub p}(d), is the quantity recommended by the International Commission on Radiation Units and Measurements (ICRU) to be used as an approximation of the protection quantity Effective Dose when performing personal dosemeter calibrations. The personal dose equivalent can be defined for any location and depth within the body. Typically, the location of interest is the trunk where personal dosemeters are usually worn and in this instance a suitable approximation is a 30 cm X 30 cm X 15 cm slab-type phantom. For this condition the personal dose equivalent is denoted as H{sub p,slab}(d) and the depths,more » d, are taken to be 0.007 cm for non-penetrating and 1 cm for penetrating radiation. In operational radiation protection a third depth, 0.3 cm, is used to approximate the dose to the lens of the eye. A number of conversion coefficients for photons are available for incident energies up to several MeV, however, data to higher energies are limited. In this work conversion coefficients up to 1 GeV have been calculated for H{sub p,slab}(10) and H{sub p,slab}(3) using both the kerma approximation and by tracking secondary charged particles. For H{sub p}(0.07) the conversion coefficients were calculated, but only to 10 MeV due to computational limitations. Additionally, conversions from air kerma to H{sub p,slab}(d) have been determined and are reported. The conversion coefficients were determined for discrete incident energies, but analytical fits of the coefficients over the energy range are provided. Since the inclusion of air can influence the production of secondary charged particles incident on the face of the phantom conversion coefficients have been determined both in vacuo and with the source and slab immersed within a sphere in air. The conversion coefficients for the personal dose equivalent are compared to the appropriate protection quantity, calculated according to the recommendations of the latest International Commission on Radiological Protection (ICRP) guidance.« less

Full-spectrum volumetric solar thermal conversion via photonic nanofluids.

PubMed

Liu, Xianglei; Xuan, Yimin

2017-10-12

Volumetric solar thermal conversion is an emerging technique for a plethora of applications such as solar thermal power generation, desalination, and solar water splitting. However, achieving broadband solar thermal absorption via dilute nanofluids is still a daunting challenge. In this work, full-spectrum volumetric solar thermal conversion is demonstrated over a thin layer of the proposed 'photonic nanofluids'. The underlying mechanism is found to be the photonic superposition of core resonances, shell plasmons, and core-shell resonances at different wavelengths, whose coexistence is enabled by the broken symmetry of specially designed composite nanoparticles, i.e., Janus nanoparticles. The solar thermal conversion efficiency can be improved by 10.8% compared with core-shell nanofluids. The extinction coefficient of Janus dimers with various configurations is also investigated to unveil the effects of particle couplings. This work provides the possibility to achieve full-spectrum volumetric solar thermal conversion, and may have potential applications in efficient solar energy harvesting and utilization.

Determining organ dose conversion coefficients for external neutron irradiation by using a voxel mouse model

PubMed Central

Zhang, Xiaomin; Xie, Xiangdong; Qu, Decheng; Ning, Jing; Zhou, Hongmei; Pan, Jie; Yang, Guoshan

2016-01-01

A set of fluence-to-dose conversion coefficients has been calculated for neutrons with energies <20 MeV using a developed voxel mouse model and Monte Carlo N-particle code (MCNP), for the purpose of neutron radiation effect evaluation. The calculation used 37 monodirectional monoenergetic neutron beams in the energy range 10−9 MeV to 20 MeV, under five different source irradiation configurations: left lateral, right lateral, dorsal–ventral, ventral–dorsal, and isotropic. Neutron fluence-to-dose conversion coefficients for selected organs of the body were presented in the paper, and the effect of irradiation geometry conditions, neutron energy and the organ location on the organ dose was discussed. The results indicated that neutron dose conversion coefficients clearly show sensitivity to irradiation geometry at neutron energy below 1 MeV. PMID:26661852

The electrical, optical, structural and thermoelectrical characterization of n- and p-type cobalt-doped SnO 2 transparent semiconducting films prepared by spray pyrolysis technique

NASA Astrophysics Data System (ADS)

Bagheri-Mohagheghi, Mohammad-Mehdi; Shokooh-Saremi, Mehrdad

2010-10-01

The electrical, optical and structural properties of Cobalt (Co) doped SnO 2 transparent semiconducting thin films, deposited by the spray pyrolysis technique, have been studied. The SnO 2:Co films, with different Co-content, were deposited on glass substrates using an aqueous-ethanol solution consisting of tin and cobalt chlorides. X-ray diffraction studies showed that the SnO 2:Co films were polycrystalline only with tin oxide phases and preferential orientations along (1 1 0) and (2 1 1) planes and grain sizes in the range 19-82 nm. Optical transmittance spectra of the films showed high transparency ∼75-90% in the visible region, decreasing with increase in Co-doping. The optical absorption edge for undoped SnO 2 films was found to be 3.76 eV, while for higher Co-doped films shifted toward higher energies (shorter wavelengths) in the range 3.76-4.04 eV and then slowly decreased again to 4.03 eV. A change in sign of the Hall voltage and Seebeck coefficient was observed for a specific acceptor dopant level ∼11.4 at% in film and interpreted as a conversion from n-type to p-type conductivity. The thermoelectric electro-motive force (e.m.f.) of the films was measured in the temperature range 300-500 K and Seebeck coefficients were found in the range from -62 to +499 μVK -1 for various Co-doped SnO 2 films.

Organ dose conversion coefficients for tube current modulated CT protocols for an adult population

NASA Astrophysics Data System (ADS)

Fu, Wanyi; Tian, Xiaoyu; Sahbaee, Pooyan; Zhang, Yakun; Segars, William Paul; Samei, Ehsan

2016-03-01

In computed tomography (CT), patient-specific organ dose can be estimated using pre-calculated organ dose conversion coefficients (organ dose normalized by CTDIvol, h factor) database, taking into account patient size and scan coverage. The conversion coefficients have been previously estimated for routine body protocol classes, grouped by scan coverage, across an adult population for fixed tube current modulated CT. The coefficients, however, do not include the widely utilized tube current (mA) modulation scheme, which significantly impacts organ dose. This study aims to extend the h factors and the corresponding dose length product (DLP) to create effective dose conversion coefficients (k factor) database incorporating various tube current modulation strengths. Fifty-eight extended cardiac-torso (XCAT) phantoms were included in this study representing population anatomy variation in clinical practice. Four mA profiles, representing weak to strong mA dependency on body attenuation, were generated for each phantom and protocol class. A validated Monte Carlo program was used to simulate the organ dose. The organ dose and effective dose was further normalized by CTDIvol and DLP to derive the h factors and k factors, respectively. The h factors and k factors were summarized in an exponential regression model as a function of body size. Such a population-based mathematical model can provide a comprehensive organ dose estimation given body size and CTDIvol. The model was integrated into an iPhone app XCATdose version 2, enhancing the 1st version based upon fixed tube current modulation. With the organ dose calculator, physicists, physicians, and patients can conveniently estimate organ dose.

Characterization of detector-systems based on CeBr3, LaBr3, SrI2 and CdZnTe for the use as dosemeters

NASA Astrophysics Data System (ADS)

Kessler, P.; Behnke, B.; Dombrowski, H.; Neumaier, S.

2017-11-01

For the upgrade of existing dosimetric early warning networks in Europe spectrometric detectors based on CeBr3, LaBr3, SrI2, and CdZnTe are investigated as possible substitutes for the current detector generation which is mainly based on gas filled detectors. The additional information on the nuclide vector which can be derived from the spectra of γ-radiation is highly useful for an appropriate response in case of a nuclear or radiological accident. The measured γ-spectra will be converted into ambient dose equivalent H* (10) using a method where the spectrum is subdivided into multiple energy bands. For each band the conversion coefficients from count rate to dose rate is determined. The derivation of these conversion coefficients is explained in this work. Both experimental and simulative approaches are investigated using quasi-mono-energetic γ-sources and synthetic spectra from Monte-Carlo simulations to determine the conversion coefficients for each detector type. Finally, precision of the obtained characterization is checked by irradiation of the detectors in different well-known photon fields with traceable dose rates.

Low-temperature atomic layer deposition of CuSbS 2 for thin-film photovoltaics

DOE PAGES

Riha, Shannon C.; Koegel, Alexandra A.; Emery, Jonathan D.; ...

2017-01-24

Copper antimony sulfide (CuSbS 2) has been gaining traction as an earth-abundant absorber for thin-film photovoltaics given its near ideal band gap for solar energy conversion (~1.5 eV), large absorption coefficient (>10 4 cm –1), and elemental abundance. Through careful in situ analysis of the deposition conditions, a low-temperature route to CuSbS 2 thin films via atomic layer deposition has been developed. After a short (15 min) post process anneal at 225 °C, the ALD-grown CuSbS 2 films were crystalline with micron-sized grains, exhibited a band gap of 1.6 eV and an absorption coefficient >10 4 cm –1, as wellmore » as a hole concentration of 10 15 cm –3. Finally, the ALD-grown CuSbS 2 films were paired with ALD-grown TiO 2 to form a photovoltaic device. This photovoltaic device architecture represents one of a very limited number of Cd-free CuSbS 2 PV device stacks reported to date, and it is the first to demonstrate an open-circuit voltage on par with CuSbS 2/CdS heterojunction PV devices. As a result, while far from optimized, this work demonstrates the potential for ALD-grown CuSbS 2 thin films in environmentally benign photovoltaics.« less

Coordinated interpersonal timing in the conversations of children who stutter and their mothers and fathers.

PubMed

Savelkoul, Eileen M; Zebrowski, Patricia M; Feldstein, Stanley; Cole-Harding, Shirley

2007-01-01

Coordinated interpersonal timing (CIT) is a measure of "conversational congruence," or "attunement," and refers to the degree to which the temporal aspects of the vocal behaviors of co-conversationalists are correlated over the course of a conversation [Jasnow, M., & Feldstein, S. (1986). Adult-like temporal characteristics of mother-infant vocal interaction. Child Development, 57, 754-761]. In the present study, CIT was examined in a group of children who stutter (CWS), and a matched group of nonstuttering children (CWDNS; children who do not stutter), during conversations with either their mother or father recorded in two separate sessions (i.e., mother-child, father-child). Separate audio signals for both the child and parent (mother or father) were analyzed using AVTA software, which allowed for the quantification of sound and silence patterns in simultaneous speech. Squared cross-correlations (i.e., coefficients of CIT) for the durations of five vocal behavior states were obtained for each subject, through time series regression analysis using lag procedures. Vocal state behaviors within conversational turns included: vocalization, pauses, turn switching pauses, and interruptive and noninterruptive simultaneous speech. Results indicated that CWS and their parents showed mutual influence (i.e., CIT in both directions, child to parent and parent to child, or bi-directional influence) for more vocal state behaviors than did CWDNS and their parents. In addition, the CWS exhibited CIT with their parents for the durations of more vocal state behaviors than did the CWDNS (i.e., unidirectional influence). Findings suggest that children who stutter may be more easily influenced by the subtle timing aspects of conversation. Taken further, some of these children may perceive conversations with their parents as either challenging or difficult because of an element of unpredictability brought into conversations by the production of stuttering, the social skills of the child, and the nature of the parent-child relationship. Consequently, these children may be engaging in more pervasive coordination of the temporal characteristics of their speech to those of their conversational partner, as a mechanism by which to more effectively manage verbal interaction. After reading this paper, the learner will be able to: (1) describe the phenomenon of coordinated interpersonal timing (CIT); (2) summarize research findings in CIT as they apply to the verbal interactions of children and their parents; (3) summarize research findings in parent-stuttering child interaction, especially those related to the temporal aspects of both parent and child conversational speech, and (4) discuss the applicability of the findings from the present study to the treatment of childhood stuttering.

A method for radiological characterization based on fluence conversion coefficients

NASA Astrophysics Data System (ADS)

Froeschl, Robert

2018-06-01

Radiological characterization of components in accelerator environments is often required to ensure adequate radiation protection during maintenance, transport and handling as well as for the selection of the proper disposal pathway. The relevant quantities are typical the weighted sums of specific activities with radionuclide-specific weighting coefficients. Traditional methods based on Monte Carlo simulations are radionuclide creation-event based or the particle fluences in the regions of interest are scored and then off-line weighted with radionuclide production cross sections. The presented method bases the radiological characterization on a set of fluence conversion coefficients. For a given irradiation profile and cool-down time, radionuclide production cross-sections, material composition and radionuclide-specific weighting coefficients, a set of particle type and energy dependent fluence conversion coefficients is computed. These fluence conversion coefficients can then be used in a Monte Carlo transport code to perform on-line weighting to directly obtain the desired radiological characterization, either by using built-in multiplier features such as in the PHITS code or by writing a dedicated user routine such as for the FLUKA code. The presented method has been validated against the standard event-based methods directly available in Monte Carlo transport codes.

Conversion of blood androgens to estrogens in normal adult men and women

PubMed Central

Longcope, Christopher; Kato, Tatsuo; Horton, Richard

1969-01-01

Continuous infusions of Δ4-androstenedione-7-3H and testosterone-7-3H have been used to demonstrate that these androgens are converted to estrone and 17β-estradiol, and contribute to the circulating blood levels of these estrogens in normal males and females. The conversion ratio (ratio of concentrations of radioactivity of free product steroid [χ-PRO] and free precursor steroid [χ-PRE], both corrected for recoveries, after an infusion of radioactive precursor steroid) for androstenedione (precursor) to estrone (product) is 0.013 in males and 0.007 in females, and the conversion ratio for testosterone (precursor) to estradiol (product) is 0.0018 in males and 0.005 in females. The transfer constant, [ρ]BBAE1, for androstenedione conversion to estrone ([ρ]BBAE1 = per cent of infused androstenedione, precursor, converted to estrone, product, when infusion and measurement are both in blood) is 1.35% in males and 0.74% in females, and the transfer constant, [ρ]BBTE2, for testosterone conversion to estradiol is 0.39% in males and 0.15% in females. Whether measured as conversion ratio or transfer constant, the peripheral aromatization of androstenedione takes place to a greater degree than that of testosterone, and, for the respective androgens, both the conversion ratio and [ρ]BB value are greater in males than females. For the androgen interconversions, [ρ]BBAT is 4.5% in males and 2.2% in females; [ρ]BBTA is 8.2% in males and 12.0% in females. Studies on the distribution coefficients (effective concentration in red cells/plasma) for precursor radioactivity were also made. In both males and females the distribution coefficient for androstenedione is 0.16-0.17 while that of testosterone is 0.01-0.03. PMID:5355335

P-Wave to Rayleigh-wave conversion coefficients for wedge corners; model experiments

USGS Publications Warehouse

Gangi, A.F.; Wesson, R.L.

1978-01-01

An analytic solution is not available for the diffraction of elastic waves by wedges; however, numerical solutions of finite-difference type are available for selected wedge angles. The P- to Rayleigh-wave conversion coefficients at wedge tips have been measured on two-dimensional seismic models for stress-free wedges with wedge angles, ??0, of 10, 30, 60, 90 and 120??. The conversion coefficients show two broad peaks and a minimum as a function of the angle between the wedge face and the direction of the incident P-wave. The minimum occurs for the P wave incident parallel to the wedge face and one maximum is near an incidence angle of 90?? to the wedge face. The amplitude of this maximum, relative to the other, decreases as the wedge angle increases. The asymmetry of the conversion coefficients, CPR(??; ??0), relative to parallel incidence (?? = 0) increases as the wedge angle increases. The locations of the maxima and the minimum as well as the asymmetry can be explained qualitatively. The conversion coefficients are measured with an accuracy of ??5% in those regions where there are no interfering waves. A comparison of the data for the 10?? wedge with the theoretical results for a half plane (0?? wedge) shows good correlation. ?? 1978.

Conversion coefficients for determining organ doses in paediatric spine radiography.

PubMed

Seidenbusch, Michael; Schneider, Karl

2014-04-01

Knowledge of organ and effective doses achieved during paediatric x-ray examinations is an important prerequisite for assessment of radiation burden to the patient. Conversion coefficients for reconstruction of organ and effective doses from entrance doses for segmental spine radiographs of 0-, 1-, 5-, 10-, 15- and 30-year-old patients are provided regarding the Guidelines of Good Radiographic Technique of the European Commission. Using the personal computer program PCXMC developed by the Finnish Centre for Radiation and Nuclear Safety (Säteilyturvakeskus STUK), conversion coefficients for conventional segmental spine radiographs were calculated performing Monte Carlo simulations in mathematical hermaphrodite phantom models describing patients of different ages. The clinical variation of beam collimation was taken into consideration by defining optimal and suboptimal radiation field settings. Conversion coefficients for the reconstruction of organ doses in about 40 organs and tissues from measured entrance doses during cervical, thoracic and lumbar spine radiographs of 0-, 1-, 5-, 10-, 15- and 30-year-old patients were calculated for the standard sagittal and lateral beam projections and the standard focus detector distance of 115 cm. The conversion coefficients presented may be used for organ dose assessments from entrance doses measured during spine radiographs of patients of all age groups and all field settings within the optimal and suboptimal standard field settings.

Temperature- and Phase-Dependent Phonon Renormalization in 1T'-MoS2.

PubMed

Tan, Sherman Jun Rong; Sarkar, Soumya; Zhao, Xiaoxu; Luo, Xin; Luo, Yong Zheng; Poh, Sock Mui; Abdelwahab, Ibrahim; Zhou, Wu; Venkatesan, Thirumalai; Chen, Wei; Quek, Su Ying; Loh, Kian Ping

2018-05-22

Polymorph engineering of 2H-MoS 2 , which can be achieved by alkali metal intercalation to obtain either the mixed 2H/1T' phases or a homogeneous 1T' phase, has received wide interest recently, since this serves as an effective route to tune the electrical and catalytic properties of MoS 2 . As opposed to an idealized single crystal-to-single crystal phase conversion, the 2H to 1T' phase conversion results in crystal domain size reduction as well as strained lattices, although how these develop with composition is not well understood. Herein, the evolution of the phonon modes in Li-intercalated 1T'-MoS 2 (Li x MoS 2 ) are investigated as a function of different 1T'-2H compositions. We observed that the strain evolution in the mixed phases is revealed by the softening of four Raman modes, B g ( J 1 ), A g ( J 3 ), E 1 2g , and A 1g , with increasing 1T' phase composition. Additionally, the first-order temperature coefficients of the 1T' phonon mode vary linearly with increasing 1T' composition, which is explained by increased electron-phonon and strain-phonon coupling.

47 CFR 3.2 - Terms and definitions.

Code of Federal Regulations, 2012 CFR

2012-10-01

... forum for dealing with all aspects of international telecommunications, including radio, telecom services and telecom facilities. (m) Linking Coefficient. The ITU mandated conversion factor used to...

47 CFR 3.2 - Terms and definitions.

Code of Federal Regulations, 2013 CFR

2013-10-01

... forum for dealing with all aspects of international telecommunications, including radio, telecom services and telecom facilities. (m) Linking Coefficient. The ITU mandated conversion factor used to...

47 CFR 3.2 - Terms and definitions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... forum for dealing with all aspects of international telecommunications, including radio, telecom services and telecom facilities. (m) Linking Coefficient. The ITU mandated conversion factor used to...

47 CFR 3.2 - Terms and definitions.

Code of Federal Regulations, 2014 CFR

2014-10-01

... forum for dealing with all aspects of international telecommunications, including radio, telecom services and telecom facilities. (m) Linking Coefficient. The ITU mandated conversion factor used to...

The B(E2;4^+1->2^+1) / B(E2;2^+1->0^+1) Ratio in Even-Even Nuclei

NASA Astrophysics Data System (ADS)

Loelius, C.; Sharon, Y. Y.; Zamick, L.; G"Urdal, G.

2009-10-01

We considered 207 even-even nuclei throughout the chart of nuclides for which the NNDC Tables had data on the energies and lifetimes of the 2^+1 and 4^+1 states. Using these data we calculated for each nucleus the electric quadrupole transition strengths B(E2;4^+1->2^+1) and B(E2;2^+1->0^+1), as well as their ratio. The internal conversion coefficients were obtained by using the NNDC HSICC calculator. For each nucleus we plotted the B(E2) ratio against A, N, and Z. We found that for close to 90% of the nuclei considered the ratio had values between 0.5 and 2.5. Most of the outliers had magic numbers of protons or neutrons. Our ratio results were compared with the theoretical predictions for this ratio by different models--10/7 in the rotational model and 2 in the simplest vibrational model. In the rotational regions (for 150 < A < 180 and A > 220) the ratios were indeed close to 10/7. For the few nuclei thought to be vibrational the ratios were usually less than 2. Otherwise, we got a wide scatter of ratio values. Hence other models, including the NpNn scheme, must be considered in interpreting these results.

Determination of the Rate Coefficients of the SO2 plus O plus M yields SO3 plus M Reaction

NASA Technical Reports Server (NTRS)

Hwang, S. M.; Cooke, J. A.; De Witt, K. J.; Rabinowitz, M. J.

2010-01-01

Rate coefficients of the title reaction R(sub 31) (SO2 +O+M yields SO3 +M) and R(sub 56) (SO2 + HO2 yields SO3 +OH), important in the conversion of S(IV) to S(VI),were obtained at T =970-1150 K and rho (sub ave) = 16.2 micro mol/cubic cm behind reflected shock waves by a perturbation method. Shock-heated H2/ O2/Ar mixtures were perturbed by adding small amounts of SO2 (1%, 2%, and 3%) and the OH temporal profiles were then measured using laser absorption spectroscopy. Reaction rate coefficients were elucidated by matching the characteristic reaction times acquired from the individual experimental absorption profiles via simultaneous optimization of k(sub 31) and k(sub 56) values in the reaction modeling (for satisfactory matches to the observed characteristic times, it was necessary to take into account R(sub 56)). In the experimental conditions of this study, R(sub 31) is in the low-pressure limit. The rate coefficient expressions fitted using the combined data of this study and the previous experimental results are k(sub 31,0)/[Ar] = 2.9 10(exp 35) T(exp ?6.0) exp(?4780 K/T ) + 6.1 10(exp 24) T(exp ?3.0) exp(?1980 K/T ) cm(sup 6) mol(exp ?2)/ s at T = 300-2500 K; k(sub 56) = 1.36 10(exp 11) exp(?3420 K/T ) cm(exp 3)/mol/s at T = 970-1150 K. Computer simulations of typical aircraft engine environments, using the reaction mechanism with the above k(sub 31,0) and k(sub 56) expressions, gave the maximum S(IV) to S(VI) conversion yield of ca. 3.5% and 2.5% for the constant density and constant pressure flow condition, respectively. Moreover, maximum conversions occur at rather higher temperatures (?1200 K) than that where the maximum k(sub 31,0) value is located (approximately 800 K). This is because the conversion yield is dependent upon not only the k(sup 31,0) and k(sup 56) values (production flux) but also the availability of H, O, and HO2 in the system (consumption flux).

Dose conversion coefficients based on the Chinese mathematical phantom and MCNP code for external photon irradiation.

PubMed

Qiu, Rui; Li, Junli; Zhang, Zhan; Liu, Liye; Bi, Lei; Ren, Li

2009-02-01

A set of conversion coefficients from kerma free-in-air to the organ-absorbed dose are presented for external monoenergetic photon beams from 10 keV to 10 MeV based on the Chinese mathematical phantom, a whole-body mathematical phantom model. The model was developed based on the methods of the Oak Ridge National Laboratory mathematical phantom series and data from the Chinese Reference Man and the Reference Asian Man. This work is carried out to obtain the conversion coefficients based on this model, which represents the characteristics of the Chinese population, as the anatomical parameters of the Chinese are different from those of Caucasians. Monte Carlo simulation with MCNP code is carried out to calculate the organ dose conversion coefficients. Before the calculation, the effects from the physics model and tally type are investigated, considering both the calculation efficiency and precision. In the calculation irradiation conditions include anterior-posterior, posterior-anterior, right lateral, left lateral, rotational and isotropic geometries. Conversion coefficients from this study are compared with those recommended in the Publication 74 of International Commission on Radiological Protection (ICRP74) since both the sets of data are calculated with mathematical phantoms. Overall, consistency between the two sets of data is observed and the difference for more than 60% of the data is below 10%. However, significant deviations are also found, mainly for the superficial organs (up to 65.9%) and bone surface (up to 66%). The big difference of the dose conversion coefficients for the superficial organs at high photon energy could be ascribed to kerma approximation for the data in ICRP74. Both anatomical variations between races and the calculation method contribute to the difference of the data for bone surface.

Comparing Hp(3) evaluated from the conversion coefficients from air kerma to personal dose equivalent for eye lens dosimetry calibrated on a new cylindrical PMMA phantom

NASA Astrophysics Data System (ADS)

Esor, J.; Sudchai, W.; Monthonwattana, S.; Pungkun, V.; Intang, A.

2017-06-01

Based on a new occupational dose limit recommended by ICRP (2011), the annual dose limit for the lens of the eye for workers should be reduced from 150 mSv/y to 20 mSv/y averaged over 5 consecutive years in which no single year exceeding 50 mSv. This new dose limit directly affects radiologists and cardiologists whose work involves high radiation exposure over 20 mSv/y. Eye lens dosimetry (Hp(3)) has become increasingly important and should be evaluated directly based on dosimeters that are worn closely to the eye. Normally, Hp(3) dose algorithm was carried out by the combination of Hp(0.07) and Hp(10) values while dosimeters were calibrated on slab PMMA phantom. Recently, there were three reports from European Union that have shown the conversion coefficients from air kerma to Hp(3). These conversion coefficients carried out by ORAMED, PTB and CEA Saclay projects were performed by using a new cylindrical head phantom. In this study, various delivered doses were calculated using those three conversion coefficients while nanoDot, small OSL dosimeters, were used for Hp(3) measurement. These calibrations were performed with a standard X-ray generator at Secondary Standard Dosimetry Laboratory (SSDL). Delivered doses (Hp(3)) using those three conversion coefficients were compared with Hp(3) from nanoDot measurements. The results showed that percentage differences between delivered doses evaluated from the conversion coefficient of each project and Hp(3) doses evaluated from the nanoDots were found to be not exceeding -11.48 %, -8.85 % and -8.85 % for ORAMED, PTB and CEA Saclay project, respectively.

Engineering quadratic nonlinear photonic crystals for frequency conversion of lasers

NASA Astrophysics Data System (ADS)

Chen, Baoqin; Hong, Lihong; Hu, Chenyang; Zhang, Chao; Liu, Rongjuan; Li, Zhiyuan

2018-03-01

Nonlinear frequency conversion offers an effective way to extend the laser wavelength range. Quadratic nonlinear photonic crystals (NPCs) are artificial materials composed of domain-inversion structures whose sign of nonlinear coefficients are modulated with desire to implement quasi-phase matching (QPM) required for nonlinear frequency conversion. These structures can offer various reciprocal lattice vectors (RLVs) to compensate the phase-mismatching during the quadratic nonlinear optical processes, including second-harmonic generation (SHG), sum-frequency generation and the cascaded third-harmonic generation (THG). The modulation pattern of the nonlinear coefficients is flexible, which can be one-dimensional or two-dimensional (2D), be periodic, quasi-periodic, aperiodic, chirped, or super-periodic. As a result, these NPCs offer very flexible QPM scheme to satisfy various nonlinear optics and laser frequency conversion problems via design of the modulation patterns and RLV spectra. In particular, we introduce the electric poling technique for fabricating QPM structures, a simple effective nonlinear coefficient model for efficiently and precisely evaluating the performance of QPM structures, the concept of super-QPM and super-periodically poled lithium niobate for finely tuning nonlinear optical interactions, the design of 2D ellipse QPM NPC structures enabling continuous tunability of SHG in a broad bandwidth by simply changing the transport direction of pump light, and chirped QPM structures that exhibit broadband RLVs and allow for simultaneous radiation of broadband SHG, THG, HHG and thus coherent white laser from a single crystal. All these technical, theoretical, and physical studies on QPM NPCs can help to gain a deeper insight on the mechanisms, approaches, and routes for flexibly controlling the interaction of lasers with various QPM NPCs for high-efficiency frequency conversion and creation of novel lasers.

Determining organ dose conversion coefficients for external neutron irradiation by using a voxel mouse model.

PubMed

Zhang, Xiaomin; Xie, Xiangdong; Qu, Decheng; Ning, Jing; Zhou, Hongmei; Pan, Jie; Yang, Guoshan

2016-03-01

A set of fluence-to-dose conversion coefficients has been calculated for neutrons with energies <20 MeV using a developed voxel mouse model and Monte Carlo N-particle code (MCNP), for the purpose of neutron radiation effect evaluation. The calculation used 37 monodirectional monoenergetic neutron beams in the energy range 10(-9) MeV to 20 MeV, under five different source irradiation configurations: left lateral, right lateral, dorsal-ventral, ventral-dorsal, and isotropic. Neutron fluence-to-dose conversion coefficients for selected organs of the body were presented in the paper, and the effect of irradiation geometry conditions, neutron energy and the organ location on the organ dose was discussed. The results indicated that neutron dose conversion coefficients clearly show sensitivity to irradiation geometry at neutron energy below 1 MeV. © The Author 2015. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.

Air kerma to Hp(3) conversion coefficients for a new cylinder phantom for photon reference radiation qualities.

PubMed

Behrens, R

2012-09-01

The International Organization for Standardization (ISO) has issued a standard series on photon reference radiation qualities (ISO 4037). In this series, no conversion coefficients are contained for the quantity personal dose equivalent at a 3 mm depth, H(p)(3). In the past, for this quantity, a slab phantom was recommended as a calibration phantom; however, a cylinder phantom much better approximates the shape of a human head than a slab phantom. Therefore, in this work, the conversion coefficients from air kerma to H(p)(3) for the cylinder phantom are supplied for X- and gamma radiation qualities defined in ISO 4037.

Fluence-to-dose conversion coefficients for heavy ions calculated using the PHITS code and the ICRP/ICRU adult reference computational phantoms.

PubMed

Sato, Tatsuhiko; Endo, Akira; Niita, Koji

2010-04-21

The fluence to organ-absorbed-dose and effective-dose conversion coefficients for heavy ions with atomic numbers up to 28 and energies from 1 MeV/nucleon to 100 GeV/nucleon were calculated using the PHITS code coupled to the ICRP/ICRU adult reference computational phantoms, following the instruction given in ICRP Publication 103 (2007 (Oxford: Pergamon)). The conversion coefficients for effective dose equivalents derived using the radiation quality factors of both Q(L) and Q(y) relationships were also estimated, utilizing the functions for calculating the probability densities of absorbed dose in terms of LET (L) and lineal energy (y), respectively, implemented in PHITS. The calculation results indicate that the effective dose can generally give a conservative estimation of the effective dose equivalent for heavy-ion exposure, although it is occasionally too conservative especially for high-energy lighter-ion irradiations. It is also found from the calculation that the conversion coefficients for the Q(y)-based effective dose equivalents are generally smaller than the corresponding Q(L)-based values because of the conceptual difference between LET and y as well as the numerical incompatibility between the Q(L) and Q(y) relationships. The calculated data of these dose conversion coefficients are very useful for the dose estimation of astronauts due to cosmic-ray exposure.

Organ dose conversion coefficients based on a voxel mouse model and MCNP code for external photon irradiation.

PubMed

Zhang, Xiaomin; Xie, Xiangdong; Cheng, Jie; Ning, Jing; Yuan, Yong; Pan, Jie; Yang, Guoshan

2012-01-01

A set of conversion coefficients from kerma free-in-air to the organ absorbed dose for external photon beams from 10 keV to 10 MeV are presented based on a newly developed voxel mouse model, for the purpose of radiation effect evaluation. The voxel mouse model was developed from colour images of successive cryosections of a normal nude male mouse, in which 14 organs or tissues were segmented manually and filled with different colours, while each colour was tagged by a specific ID number for implementation of mouse model in Monte Carlo N-particle code (MCNP). Monte Carlo simulation with MCNP was carried out to obtain organ dose conversion coefficients for 22 external monoenergetic photon beams between 10 keV and 10 MeV under five different irradiation geometries conditions (left lateral, right lateral, dorsal-ventral, ventral-dorsal, and isotropic). Organ dose conversion coefficients were presented in tables and compared with the published data based on a rat model to investigate the effect of body size and weight on the organ dose. The calculated and comparison results show that the organ dose conversion coefficients varying the photon energy exhibits similar trend for most organs except for the bone and skin, and the organ dose is sensitive to body size and weight at a photon energy approximately <0.1 MeV.

Boundary layer measurements of the OH radical in the vicinity of an isolated power plant plume - SO2 and NO2 chemical conversion times

NASA Technical Reports Server (NTRS)

Davis, D. D.; Philen, D.; Mcgee, T.; Heaps, W.

1979-01-01

Direct measurements of the OH radical in the vicinity of an isolated power plant plume are reported. These measurements were used to estimate the conversion time of SO2 to H2SO4-sulfate aerosol via the initiating step OH + SO2 + M yields HSO3. Using the near-high-noon measured value of OH (9.5 million per cu cm), resulted in a 1/e conversion time of 1.4 days. The latter lifetime would correspond to a conversion rate of about 2%/hr. When the lifetime calculation was modified to take into consideration the OH diurnal cycle, the 1/e conversion time for SO2 was found to be 4.4 days, giving an apparent overall rate of conversion of about 0.7%/hr. Similar calculations carried out for the conversion of NO2 to NHO3 resulted in 1/e lifetimes for NO2 of 2-3 h for midday time periods.

Electronic Band Structure Tuning of Highly-Mismatched-Alloys for Energy Conversion Applications

NASA Astrophysics Data System (ADS)

Ting, Min

Highly-mismatched alloys: ZnO1-xTe x and GaN1-xSb x are discussed within the context of finding the suitable material for a cost-effective Si-based tandem solar cell (SBTSC). SBTSC is an attractive concept for breaking through the energy conversion efficiency theoretical limit of a single junction solar cell. Combining with a material of 1.8 eV band gap, SBTSC can theoretically achieve energy conversion efficiency > 45%. ZnO and GaN are wide band gap semiconductors. Alloying Te in ZnO and alloying Sb in GaN result in large band gap reduction to < 2 eV from 3.3 eV and 3.4 eV respectively. The band gap reduction is majorly achieved by the upward shift of valence band (VB). Incorporating Te in ZnO modifies the VB of ZnO through the valence-band anticrossing (VBAC) interaction between localized Te states and ZnO VB delocalized states, which forms a Te-derived VB at 1 eV above the host VB. Similar band structure modification is resulted from alloying Sb in GaN. Zn1-xTex and GaN 1-xSbx thin films are synthesized across the whole composition range by pulsed laser deposition (PLD) and low temperature molecular beam epitaxy (LT-MBE) respectively. The electronic band edges of these alloys are measured by synchrotron X-ray absorption, emission, and the X-ray photoelectron spectroscopies. Modeling the optical absorption coefficient with the band anticrossing (BAC) model revealed that the Te and Sb defect levels to be at 0.99 eV and 1.2 eV above the VB of ZnO and GaN respectively. Electrically, Zn1-xTex is readily n-type conductive and GaN1-xSbx is strongly p-type conductive. A heterojunction device of p-type GaN 0.93Sb0.07 with n-type ZnO0.77Te0.93 upper cell (band gap at 1.8 eV) on Si bottom cell is proposed as a promising SBTSC device.

Fundamental limits of ultrathin metasurfaces

PubMed Central

Arbabi, Amir; Faraon, Andrei

2017-01-01

We present a set of universal relations which relate the local transmission, reflection, and polarization conversion coefficients of a general class of non-magnetic passive ultrathin metasurfaces. We show that these relations are a result of equal forward and backward scattering by single layer ultrathin metasurfaces, and they lead to confinement of the transmission, reflection, and polarization conversion coefficients to limited regions of the complex plane. Using these relations, we investigate the effect of the presence of a substrate, and show that the maximum polarization conversion efficiency for a transmissive metasurface decreases as the refractive index contrast between the substrate and cladding layer increases. Furthermore, we demonstrate that a single layer reflective metasurface can achieve full 2π phase shift coverage without altering the polarization if it is illuminated from the higher refractive index material. We also discuss two approaches for achieving asymmetric scattering from metasurfaces, and realizing metasurfaces which overcome the performance limitations of single layer ultrathin metasurfaces. PMID:28262739

The influence of surface functionalization on thermal transport and thermoelectric properties of MXene monolayers.

PubMed

Sarikurt, Sevil; Çakır, Deniz; Keçeli, Murat; Sevik, Cem

2018-05-10

The newest members of a two-dimensional material family, involving transition metal carbides and nitrides (called MXenes), have garnered increasing attention due to their tunable electronic and thermal properties depending on the chemical composition and functionalization. This flexibility can be exploited to fabricate efficient electrochemical energy storage (batteries) and energy conversion (thermoelectric) devices. In this study, we calculated the Seebeck coefficients and lattice thermal conductivity values of oxygen terminated M2CO2 (where M = Ti, Zr, Hf, Sc) monolayer MXene crystals in two different functionalization configurations (model-II (MD-II) and model-III (MD-III)), using density functional theory and Boltzmann transport theory. We estimated the thermoelectric figure-of-merit, zT, of these materials by two different approaches, as well. First of all, we found that the structural model (i.e. adsorption site of oxygen atom on the surface of MXene) has a paramount impact on the electronic and thermoelectric properties of MXene crystals, which can be exploited to engineer the thermoelectric properties of these materials. The lattice thermal conductivity κl, Seebeck coefficient and zT values may vary by 40% depending on the structural model. The MD-III configuration always has the larger band gap, Seebeck coefficient and zT, and smaller κl as compared to the MD-II structure due to a larger band gap, highly flat valence band and reduced crystal symmetry in the former. The MD-III configuration of Ti2CO2 and Zr2CO2 has the lowest κl as compared to the same configuration of Hf2CO2 and Sc2CO2. Among all the considered structures, the MD-II configuration of Hf2CO2 has the highest κl, and Ti2CO2 and Zr2CO2 in the MD-III configuration have the lowest κl. For instance, while the band gap of the MD-II configuration of Ti2CO2 is 0.26 eV, it becomes 0.69 eV in MD-III. The zTmax value may reach up to 1.1 depending on the structural model of MXene.

Dose conversion coefficients for neutron exposure to the lens of the human eye.

PubMed

Manger, R P; Bellamy, M B; Eckerman, K F

2012-03-01

Dose conversion coefficients for the lens of the human eye have been calculated for neutron exposure at energies from 1 × 10(-9) to 20 MeV and several standard orientations: anterior-to-posterior, rotational and right lateral. MCNPX version 2.6.0, a Monte Carlo-based particle transport package, was used to determine the energy deposited in the lens of the eye. The human eyeball model was updated by partitioning the lens into sensitive and insensitive volumes as the anterior portion (sensitive volume) of the lens being more radiosensitive and prone to cataract formation. The updated eye model was used with the adult UF-ORNL mathematical phantom in the MCNPX transport calculations.

Measurements of multipolarities in 227Ra as tests of evidence for stable octupole deformation

NASA Astrophysics Data System (ADS)

Borge, M. J. G.; Burke, D. G.; Gietz, H.; Hill, P.; Kaffrell, N.; Kurcewicz, W.; Løvhøiden, G.; Mattsson, S.; Naumann, R. A.; Nybø, K.; Nyman, G.; Thorsteinsen, T. F.

1987-03-01

Multipolarities of ~30 transitions in 227Ra have been established by measuring conversion electrons following the β - decay of 227Fr. For this purpose a "mini-orange"-type electron spectrometer has been constructed. The 227Fr isotopes were produced by the ISOLDE on-line separator at the CERN Synchro-cyclotron. Internal conversion coefficients were obtained from singles spectra and also from simultaneous γe - and γγ coincidence measurements. The new results support the placement of levels and transitions in the earlier level scheme but require changes in the previously assigned parities for four of the levels. Also, one E0 transition was identified. The results are consistent with previous interpretations for most of the levels that have been used to argue in favour of a small permanent octupole deformation for 227Ra.

Measurement of Upconversion in Er:YAG via Z-scan

DTIC Science & Technology

2011-10-01

4I9=2) is used to fit the data (Fig. 1). Included in the model is a rate equation for the population of each mani- fold, Ni, where i runs from 1 to 4...þW31Þ; ð3Þ dN4 dt ¼ CupN22 − N4ðW43 þW42 þW41Þ: ð4Þ Here, I is the laser intensity, σ is the absolute cross section, Wij is the relaxation rate from...level i to level j, Cup is the up- conversion coefficient, and f aðf eÞ is the probability given by the Boltzmann distribution that an ion in the 4I15=2

Equilibrium water and solute uptake in silicone hydrogels.

PubMed

Liu, D E; Dursch, T J; Oh, Y; Bregante, D T; Chan, S Y; Radke, C J

2015-05-01

Equilibrium water content of and solute partitioning in silicone hydrogels (SiHys) are investigated using gravimetric analysis, fluorescence confocal laser-scanning microscopy (FCLSM), and back extraction with UV/Vis-absorption spectrophotometry. Synthesized silicone hydrogels consist of silicone monomer, hydrophilic monomer, cross-linking agent, and triblock-copolymer macromer used as an amphiphilic compatibilizer to prevent macrophase separation. In all cases, immiscibility of the silicone and hydrophilic polymers results in microphase-separated morphologies. To investigate solute uptake in each of the SiHy microphases, equilibrium partition coefficients are obtained for two hydrophilic solutes (i.e., theophylline and caffeine dissolved in aqueous phosphate-buffered saline) and two oleophilic solutes (i.e., Nile Red and Bodipy Green dissolved in silicone oil), respectively. Measured water contents and aqueous-solute partition coefficients increase linearly with increasing solvent-free hydrophilic-polymer volume fraction. Conversely, oleophilic-solute partition coefficients decrease linearly with rising solvent-free hydrophilic-polymer volume fraction (i.e., decreasing hydrophobic silicone-polymer fraction). We quantitatively predict equilibrium SiHy water and solute uptake assuming that water and aqueous solutes reside only in hydrophilic microdomains, whereas oleophilic solutes partition predominately into silicone microdomains. Predicted water contents and solute partition coefficients are in excellent agreement with experiment. Our new procedure permits a priori estimation of SiHy water contents and solute partition coefficients based solely on properties of silicone and hydrophilic homopolymer hydrogels, eliminating the need for further mixed-polymer-hydrogel experiments. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

A new fifth parameter for transverse isotropy III: reflection and transmission coefficients

NASA Astrophysics Data System (ADS)

Kawakatsu, Hitoshi

2018-04-01

The effect of the newly defined fifth parameter, ηκ, of transverse anisotropy to the reflection and transmission coefficients, especially for P-to-S and S-to-P conversion coefficients, is examined. While ηκ systematically affects the P-to-S and S-to-P conversions, in the incidence angle range of the practical interest of receiver function studies, the effect may be asymmetric in a sense that P-wave receiver function is affected more than S-receiver function in terms of amplitude. This asymmetry may help resolving ηκ via extensive receiver function analysis. It is also found that P-wave anisotropy significantly influences P-to-S and S-to-P conversion coefficients that complicates the interpretation of receiver functions, because, for isotropic media, we typically attribute the primary receiver function signals to S-wave velocity changes but not to P-wave changes.

Mpeg2 codec HD improvements with medical and robotic imaging benefits

NASA Astrophysics Data System (ADS)

Picard, Wayne F. J.

2010-02-01

In this report, we propose an efficient scheme to use High Definition Television (HDTV) in a console or notebook format as a computer terminal in addition to their role as TV display unit. In the proposed scheme, we assume that the main computer is situated at a remote location. The computer raster in the remote server is compressed using an HD E- >Mpeg2 encoder and transmitted to the terminal at home. The built-in E->Mpeg2 decoder in the terminal decompresses the compressed bit stream, and displays the raster. The terminal will be fitted with a mouse and keyboard, through which the interaction with the remote computer server can be performed via a communications back channel. The terminal in a notebook format can thus be used as a high resolution computer and multimedia device. We will consider developments such as the required HD enhanced Mpeg2 resolution (E->Mpeg2) and its medical ramifications due to improvements on compressed image quality with 2D to 3D conversion (Mpeg3) and using the compressed Discrete Cosine Transform coefficients in the reality compression of vision and control of medical robotic surgeons.

Dose conversion coefficients for neutron exposure to the lens of the human eye

DOE Office of Scientific and Technical Information (OSTI.GOV)

Manger, Ryan P; Bellamy, Michael B; Eckerman, Keith F

Dose conversion coefficients for the lens of the human eye have been calculated for neutron exposure at energies from 1 x 10{sup -9} to 20 MeV and several standard orientations: anterior-to-posterior, rotational and right lateral. MCNPX version 2.6.0, a Monte Carlo-based particle transport package, was used to determine the energy deposited in the lens of the eye. The human eyeball model was updated by partitioning the lens into sensitive and insensitive volumes as the anterior portion (sensitive volume) of the lens being more radiosensitive and prone to cataract formation. The updated eye model was used with the adult UF-ORNL mathematicalmore » phantom in the MCNPX transport calculations.« less

Exposure to 137Cs deposited in soil – A Monte Carlo study

NASA Astrophysics Data System (ADS)

da Silveira, Lucas M.; Pereira, Marco A. M.; Neves, Lucio P.; Perini, Ana P.; Belinato, Walmir; Caldas, Linda V. E.; Santos, William S.

2018-03-01

In the event of an environmental contamination with radioactive materials, one of the most dangerous materials is 137Cs. In order to evaluate the radiation doses involved in an environmental contamination of soil, with 137Cs, we carried out a computational dosimetric study. We determined the radiation conversion coefficients (CC) for effective (E) and equivalent (H T) doses, using a male and a female anthropomorphic phantoms. These phantoms were coupled with the MCNPX (2.7.0) Monte Carlo simulation software, for three different types of soil. The highest CC[H T] values were for the gonads and skin (male) and bone marrow and skin (female). We found no difference for the different types of soil.

Limitations of Cs3Bi2I9 as lead-free photovoltaic absorber materials.

PubMed

Ghosh, Biplab; Wu, Bo; Mulmudi, Hemant Kumar; Guet, Claude; Weber, Klaus; Sum, Tze Chien; Mhaisalkar, Subodh G; Mathews, Nripan

2018-01-17

Lead (Pb) halide perovskites have attracted tremendous attention in recent years due to their rich optoelectronic properties, which have resulted in more than 22% power conversion efficient photovoltaics. Nevertheless, Pb-metal toxicity remains a huge hurdle for extensive applications of these compounds. Thus, alternative compounds with similar optoelectronic properties need to be developed. Bismuth possesses similar electronic structure as that of lead with the presence of ns2 electrons that exhibit rich structural variety as well as interesting optical and electronic properties. Herein, we critically assess Cs3Bi2I9 as a candidate for thin-film solar cell absorber. Despite a reasonable optical bandgap (~2eV) and absorption coefficient, the power conversion efficiency of the Cs3Bi2I9 mesoscopic solar cells was found to be severely lacking, limited by poor photocurrent density. The efficiency of the Cs3Bi2I9 solar cell can be slightly improved by changing the stoichiometry of the precursor solutions. We have investigated the possible reasons behind the poor performance of Cs3Bi2I9 by transient absorption and luminescence spectroscopy. Comparison between thin-films and single crystals highlights the presence of intrinsic defects in thin-films which act as nonradiative recombination centers.

The effect of the DSSC photoanode area based on TiO2/Ag on the conversion efficiency of solar energy into electrical energy

NASA Astrophysics Data System (ADS)

Ibrayev, N.; Serikov, T.; Zavgorodniy, A.; Sadykova, A.

2018-01-01

A module based on dye-sensitized solar cells with Ag/TiO2 structure was developed. It is shown that the addition of the core-shell structure to the semiconductor film of titanium dioxide, where the nanoparticle Ag serves as the core, and the TiO2 is shell, increases the coefficient of solar energy conversion into electrical energy. The effect of the photoanode area on the efficiency of conversion of solar energy into electrical energy is studied. It is shown that the density of the photocurrent decreases with increasing of the photoanode area, which leads to a drop in the efficiency of solar cells.

Radiometer offsets and count conversion coefficients for the Earth Radiation Budget Experiment (ERBE) spacecraft for the years 1984, 1985, and 1986

NASA Technical Reports Server (NTRS)

Paden, Jack; Pandey, Dhirendra K.; Shivakumar, Netra D.; Stassi, Joseph C.; Wilson, Robert; Bolden, William; Thomas, Susan; Gibson, M. Alan

1991-01-01

A compendium is presented of the ground and inflight scanner and nonscanner offsets and count conversion (gain) coefficients used for the Earth Radiation Budget Experiment (ERBE) production processing of data from the ERBS, NOAA-9, and NOAA-10 satellites for the 1 Nov. 1984 to 31 Dec. 1986.

Fluence-to-dose conversion coefficients for neutrons and protons calculated using the PHITS code and ICRP/ICRU adult reference computational phantoms.

PubMed

Sato, Tatsuhiko; Endo, Akira; Zankl, Maria; Petoussi-Henss, Nina; Niita, Koji

2009-04-07

The fluence to organ-dose and effective-dose conversion coefficients for neutrons and protons with energies up to 100 GeV was calculated using the PHITS code coupled to male and female adult reference computational phantoms, which are to be released as a common ICRP/ICRU publication. For the calculation, the radiation and tissue weighting factors, w(R) and w(T), respectively, as revised in ICRP Publication 103 were employed. The conversion coefficients for effective dose equivalents derived using the radiation quality factors of both Q(L) and Q(y) relationships were also estimated, utilizing the functions for calculating the probability densities of the absorbed dose in terms of LET (L) and lineal energy (y), respectively, implemented in PHITS. By comparing these data with the corresponding data for the effective dose, we found that the numerical compatibilities of the revised w(R) with the Q(L) and Q(y) relationships are fairly established. The calculated data of these dose conversion coefficients are indispensable for constructing the radiation protection systems based on the new recommendations given in ICRP103 for aircrews and astronauts, as well as for workers in accelerators and nuclear facilities.

Giant self-biased converse magnetoelectric effect in multiferroic heterostructure with single-phase magnetostrictive materials

NASA Astrophysics Data System (ADS)

Zhang, Jitao; Li, Ping; Wen, Yumei; He, Wei; Yang, Aichao; Wang, Decai; Yang, Chao; Lu, Caijiang

2014-10-01

Giant self-biased converse magnetoelectric (CME) effects with obvious hysteretic behaviors are systematically investigated in two-phase SmFe2/PZT [Pb(Zr1-x, Tix)O3] multiferroic laminates at room temperature. Taking advantage of the huge anisotropic field of SmFe2 plate, large remnant CME coupling is provoked by this field instead of permanent magnets to bias the laminate. Consequently, bitable magnetization status switching is realized through a smaller ac voltage far below the electric coercive field in the absence of magnetic bias field. Experiments demonstrate that a large remnant CME coefficient (αCME) of 0.007 mG/V is achieved, exhibiting ˜50 times higher CME coefficient than the previous laminate composite multi-phase magnetostrictive plates. These results provide promising applications for realization of high-density magnetoelectric random access memories (MERAMs) devices with lower energy consumption.

High absorption coefficients of the CuSb(Se,Te)2 and CuBi(S,Se)2 alloys enable high-efficient 100 nm thin-film photovoltaics

NASA Astrophysics Data System (ADS)

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.

Planck 2013 results. IX. HFI spectral response

NASA Astrophysics Data System (ADS)

Planck Collaboration; Ade, P. A. R.; Aghanim, N.; Armitage-Caplan, C.; Arnaud, M.; Ashdown, M.; Atrio-Barandela, F.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Battaner, E.; Benabed, K.; Benoît, A.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bobin, J.; Bock, J. J.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Bridges, M.; Bucher, M.; Burigana, C.; Cardoso, J.-F.; Catalano, A.; Challinor, A.; Chamballu, A.; Chary, R.-R.; Chen, X.; Chiang, H. C.; Chiang, L.-Y.; Christensen, P. R.; Church, S.; Clements, D. L.; Colombi, S.; Colombo, L. P. L.; Combet, C.; Comis, B.; Couchot, F.; Coulais, A.; Crill, B. P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R. D.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Delouis, J.-M.; Désert, F.-X.; Dickinson, C.; Diego, J. M.; Dole, H.; Donzelli, S.; Doré, O.; Douspis, M.; Dupac, X.; Efstathiou, G.; Enßlin, T. A.; Eriksen, H. K.; Falgarone, E.; Finelli, F.; Forni, O.; Frailis, M.; Franceschi, E.; Galeotta, S.; Ganga, K.; Giard, M.; Giraud-Héraud, Y.; González-Nuevo, J.; Górski, K. M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Hansen, F. K.; Hanson, D.; Harrison, D.; Henrot-Versillé, S.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Holmes, W. A.; Hornstrup, A.; Hovest, W.; Huffenberger, K. M.; Hurier, G.; Jaffe, A. H.; Jaffe, T. R.; Jones, W. C.; Juvela, M.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Kneissl, R.; Knoche, J.; Knox, L.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lamarre, J.-M.; Lasenby, A.; Laureijs, R. J.; Lawrence, C. R.; Leahy, J. P.; Leonardi, R.; Leroy, C.; Lesgourgues, J.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Maffei, B.; Mandolesi, N.; Maris, M.; Marshall, D. J.; Martin, P. G.; Martínez-González, E.; Masi, S.; Massardi, M.; Matarrese, S.; Matthai, F.; Mazzotta, P.; McGehee, P.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Mitra, S.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Munshi, D.; Murphy, J. A.; Naselsky, P.; Nati, F.; Natoli, P.; Netterfield, C. B.; Nørgaard-Nielsen, H. U.; North, C.; Noviello, F.; Novikov, D.; Novikov, I.; Osborne, S.; Oxborrow, C. A.; Paci, F.; Pagano, L.; Pajot, F.; Paoletti, D.; Pasian, F.; Patanchon, G.; Perdereau, O.; Perotto, L.; Perrotta, F.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Ponthieu, N.; Popa, L.; Poutanen, T.; Pratt, G. W.; Prézeau, G.; Prunet, S.; Puget, J.-L.; Rachen, J. P.; Reinecke, M.; Remazeilles, M.; Renault, C.; Ricciardi, S.; Riller, T.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Roudier, G.; Rusholme, B.; Santos, D.; Savini, G.; Scott, D.; Shellard, E. P. S.; Spencer, L. D.; Starck, J.-L.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sureau, F.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Tavagnacco, D.; Terenzi, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Umana, G.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vielva, P.; Villa, F.; Vittorio, N.; Wade, L. A.; Wandelt, B. D.; Yvon, D.; Zacchei, A.; Zonca, A.

2014-11-01

The Planck High Frequency Instrument (HFI) spectral response was determined through a series of ground based tests conducted with the HFI focal plane in a cryogenic environment prior to launch. The main goal of the spectral transmission tests was to measure the relative spectral response (includingthe level of out-of-band signal rejection) of all HFI detectors to a known source of electromagnetic radiation individually. This was determined by measuring the interferometric output of a continuously scanned Fourier transform spectrometer with all HFI detectors. As there is no on-board spectrometer within HFI, the ground-based spectral response experiments provide the definitive data set for the relative spectral calibration of the HFI. Knowledge of the relative variations in the spectral response between HFI detectors allows for a more thorough analysis of the HFI data. The spectral response of the HFI is used in Planck data analysis and component separation, this includes extraction of CO emission observed within Planck bands, dust emission, Sunyaev-Zeldovich sources, and intensity to polarization leakage. The HFI spectral response data have also been used to provide unit conversion and colour correction analysis tools. While previous papers describe the pre-flight experiments conducted on the Planck HFI, this paper focusses on the analysis of the pre-flight spectral response measurements and the derivation of data products, e.g. band-average spectra, unit conversion coefficients, and colour correction coefficients, all with related uncertainties. Verifications of the HFI spectral response data are provided through comparisons with photometric HFI flight data. This validation includes use of HFI zodiacal emission observations to demonstrate out-of-band spectral signal rejection better than 108. The accuracy of the HFI relative spectral response data is verified through comparison with complementary flight-data based unit conversion coefficients and colour correction coefficients. These coefficients include those based upon HFI observations of CO, dust, and Sunyaev-Zeldovich emission. General agreement is observed between the ground-based spectral characterization of HFI and corresponding in-flight observations, within the quoted uncertainty of each; explanations are provided for any discrepancies.

The Cu2ZnSnSe4 thin films solar cells synthesized by electrodeposition route

NASA Astrophysics Data System (ADS)

Li, Ji; Ma, Tuteng; Wei, Ming; Liu, Weifeng; Jiang, Guoshun; Zhu, Changfei

2012-06-01

An electrodeposition route for preparing Cu2ZnSnSe4 thin films for thin film solar cell absorber layers is demonstrated. The Cu2ZnSnSe4 thin films are prepared by co-electrodeposition Cu-Zn-Sn metallic precursor and subsequently annealing in element selenium atmosphere. The structure, composition and optical properties of the films were investigated by X-ray diffraction (XRD), Raman spectrometry, energy dispersive spectrometry (EDS) and UV-VIS absorption spectroscopy. The Cu2ZnSnSe4 thin film with high crystalline quality was obtained, the band gap and absorption coefficient were 1.0 eV and 10-4 cm-1, which is quite suitable for solar cells fabrication. A solar cell with the structure of ZnO:Al/i-ZnO/CdS/Cu2ZnSnSe4/Mo/glass was fabricated and achieved an conversion efficiency of 1.7%.

NONLINEAR AND FIBER OPTICS: Conversion of pulsed laser radiation from the 9.3-9.6 μm range to the second harmonic in ZnGeP2 crystals

NASA Astrophysics Data System (ADS)

Andreev, Yu M.; Bykanov, A. N.; Gribenyukov, A. I.; Zuev, V. V.; Karyshev, V. D.; Kisletsov, A. V.; Kovalev, I. O.; Konov, Vitalii I.; Kuz'min, G. P.; Nesterenko, A. A.; Osorgin, A. E.; Starodumov, Yu M.; Chapliev, N. I.

1990-04-01

A pulsed TEA CO2 laser was used in an investigation of the influence of the pump radiation parameters (mode composition, wavelength, pulse duration), of the focusing conditions, of the properties of the material (absorption coefficient), and of the operating conditions (temperature) on the efficiency of conversion to the second harmonic and on the angular dependences of phase matching in ZnGeP2 crystals. The calculated results were found to be in good agreement with the experimental data.

The influence of patient size on dose conversion coefficients: a hybrid phantom study for adult cardiac catheterization

NASA Astrophysics Data System (ADS)

Johnson, Perry; Lee, Choonsik; Johnson, Kevin; Siragusa, Daniel; Bolch, Wesley E.

2009-06-01

In this study, the influence of patient size on organ and effective dose conversion coefficients (DCCs) was investigated for a representative interventional fluoroscopic procedure—cardiac catheterization. The study was performed using hybrid phantoms representing an underweight, average and overweight American adult male. Reference body sizes were determined using the NHANES III database and parameterized based on standing height and total body mass. Organ and effective dose conversion coefficients were calculated for anterior-posterior, posterior-anterior, left anterior oblique and right anterior oblique projections using the Monte Carlo code MCNPX 2.5.0 with the metric dose area product being used as the normalization factor. Results show body size to have a clear influence on DCCs which increased noticeably when body size decreased. It was also shown that if patient size is neglected when choosing a DCC, the organ and effective dose will be underestimated to an underweight patient and will be overestimated to an underweight patient, with errors as large as 113% for certain projections. Results were further compared with those published for a KTMAN-2 Korean patient-specific tomographic phantom. The published DCCs aligned best with the hybrid phantom which most closely matched in overall body size. These results highlighted the need for and the advantages of phantom-patient matching, and it is recommended that hybrid phantoms be used to create a more diverse library of patient-dependent anthropomorphic phantoms for medical dose reconstruction.

Weak e+e- lines from internal pair conversion observed in collisions of 238U with heavy nuclei

NASA Astrophysics Data System (ADS)

Heinz, S.; Berdermann, E.; Heine, F.; Joeres, O.; Kienle, P.; Koenig, I.; Koenig, W.; Kozhuharov, C.; Leinberger, U.; Rhein, M.; Schröter, A.; Tsertos, H.

1998-01-01

We present the results of a Doppler-shift correction to the measured e+e- sum-energy spectra obtained from e+e- coincidence measurements in 238U +206Pb and 238U +181Ta collisions at beam energies close to the Coulomb barrier, using an improved experimental setup at the double-Orange spectrometer of GSI. Internal-Pair-Conversion (IPC) e+e- pairs from discrete nuclear transitions of a moving emitter have been observed following Coulomb excitation of the 1.844 MeV (E1) transition in 206Pb and neutron transfer to the 1.770 MeV (M1) transition in 207Pb. In the collision system 238U +181Ta, IPC transitions were observed from the Ta-like as well as from the U-like nuclei. In all systems the Doppler-shift corrected e+e- sum-energy spectra show weak lines at the energies expected from the corresponding γ ray spectra with cross sections being consistent with the measured excitation cross sections of the γ lines and the theoretically predicted IPC coefficients. No other than IPC e+e- sum-energy lines were found in the measured spectra. The transfer cross sections show a strong dependence on the distance of closest approach (Rmin), thus signaling also a strong dependence on the bombarding energy close to the Coulomb barrier.

Mu2e, a coherent μ --> e conversion experiment at Fermilab

NASA Astrophysics Data System (ADS)

Brown, D. N.; Mu2e Collaboration

2012-09-01

We describe a proposed experiment to search for Charged Lepton Flavor Violation (CLFV) using stopped muons at Fermilab. A primary Proton beam will strike a gold target, producing pions which decay to muons. Low-momentum negative muons will be collected, selected, and transported by a custom arrangement of solenoidal magnets and collimators. Muons will stop in thin foil targets, creating muonic atoms with significant nuclear overlap. Mu2e will search for the coherent conversion of nuclear bound muons to electrons, with an experimental signature of a single mono-energetic electron. Conversion electrons will be detected and measured in a low-mass straw tracker and a crystal calorimeter. Mu2e will have a sensitivity four orders of magnitude better than the most sensitive published result for μ → e conversion, and will have complementary physics reach to LHC experiments and μ → eγ decay experiments such as MEG.

MO-E-17A-08: Attenuation-Based Size Adjusted, Scanner-Independent Organ Dose Estimates for Head CT Exams: TG 204 for Head CT

DOE Office of Scientific and Technical Information (OSTI.GOV)

McMillan, K; Bostani, M; Cagnon, C

Purpose: AAPM Task Group 204 described size specific dose estimates (SSDE) for body scans. The purpose of this work is to use a similar approach to develop patient-specific, scanner-independent organ dose estimates for head CT exams using an attenuation-based size metric. Methods: For eight patient models from the GSF family of voxelized phantoms, dose to brain and lens of the eye was estimated using Monte Carlo simulations of contiguous axial scans for 64-slice MDCT scanners from four major manufacturers. Organ doses were normalized by scannerspecific 16 cm CTDIvol values and averaged across all scanners to obtain scanner-independent CTDIvol-to-organ-dose conversion coefficientsmore » for each patient model. Head size was measured at the first slice superior to the eyes; patient perimeter and effective diameter (ED) were measured directly from the GSF data. Because the GSF models use organ identification codes instead of Hounsfield units, water equivalent diameter (WED) was estimated indirectly. Using the image data from 42 patients ranging from 2 weeks old to adult, the perimeter, ED and WED size metrics were obtained and correlations between each metric were established. Applying these correlations to the GSF perimeter and ED measurements, WED was calculated for each model. The relationship between the various patient size metrics and CTDIvol-to-organ-dose conversion coefficients was then described. Results: The analysis of patient images demonstrated the correlation between WED and ED across a wide range of patient sizes. When applied to the GSF patient models, an exponential relationship between CTDIvol-to-organ-dose conversion coefficients and the WED size metric was observed with correlation coefficients of 0.93 and 0.77 for the brain and lens of the eye, respectively. Conclusion: Strong correlation exists between CTDIvol normalized brain dose and WED. For the lens of the eye, a lower correlation is observed, primarily due to surface dose variations. Funding Support: Siemens-UCLA Radiology Master Research Agreement; Disclosures - Michael McNitt-Gray: Institutional Research Agreement, Siemens AG; Research Support, Siemens AG; Consultant, Flaherty Sensabaugh Bonasso PLLC; Consultant, Fulbright and Jaworski.« less

Non-analytic terms from nested divergences in maximal supergravity

NASA Astrophysics Data System (ADS)

Basu, Anirban

2016-07-01

The {D}4{{ R }}4 and {D}6{{ R }}4 coefficient functions in the effective action of type II string theory compactified on T d contain terms of the form {{ E }}1{{ln}}{g}d and {{ E }}2{({{ln}}{g}d)}2 in specific dimensions, where g d is the T-duality invariant string coupling, and {{ E }}1 and {{ E }}2 are U-duality invariant coefficient functions. We derive these non-analytic terms from nested ultraviolet divergences in two and three loop maximal supergravity. For the {D}4{{ R }}4 coupling, the contribution involves {{ E }}{{ R }4}{{ln}}{g}d, while for the {D}6{{ R }}4 coupling, it involves {{ E }}{{ R }4}{{ln}}{g}d, {{ E }}{D2{{ R }}4}{({{ln}}{g}d)}2 and {{ E }}{D4{{ R }}4}{{ln}}{g}d; where {{ E }}{{ R }4}, {{ E }}{D2{{ R }}4} and {{ E }}{D4{{ R }}4} are the {{ R }}4, {D}2{{ R }}4 and {D}4{{ R }}4 coefficient functions respectively. The contribution from {{ E }}{D2{{ R }}4}, the coefficient function of an amplitude that vanishes onshell, arises from a two loop nested subdivergence of the three loop amplitude.

Fluence-to-Absorbed Dose Conversion Coefficients for Use in Radiological Protection of Embryo and Foetus Against External Exposure to Muons from 20MeV to 50GeV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen Jing

2008-08-07

This study used the Monte-Carlo code MCNPX to determine mean absorbed doses to the embryo and foetus when the mother is exposed to external muon fields. Monoenergetic muons ranging from 20 MeV to 50 GeV were considered. The irradiation geometries include anteroposterior (AP), postero-anterior (PA), lateral (LAT), rotational (ROT), isotropic (ISO), and top-down (TOP). At each of these irradiation geometries, absorbed doses to the foetal body were calculated for the embryo of 8 weeks and the foetus of 3, 6 or 9 months, respectively. Muon fluence-to-absorbed-dose conversion coefficients were derived for the four prenatal ages. Since such conversion coefficients aremore » yet unknown, the results presented here fill a data gap.« less

Spin-dependent μ → e conversion

DOE PAGES

Cirigliano, Vincenzo; Davidson, Sacha; Kuno, Yoshitaka

2017-05-22

The experimental sensitivity to μ→e conversion on nuclei is expected to improve by four orders of magnitude in coming years. Here, we consider the impact of μ→e flavour-changing tensor and axial-vector four-fermion operators which couple to the spin of nucleons. Such operators, which have not previously been considered, contribute to μ→e conversion in three ways: in nuclei with spin they mediate a spin-dependent transition; in all nuclei they contribute to the coherent (A 2-enhanced) spin-independent conversion via finite recoil effects and via loop mixing with dipole, scalar, and vector operators. Furthermore, we estimate the spin-dependent rate in Aluminium (the targetmore » of the upcoming COMET and Mu2e experiments), show that the loop effects give the greatest sensitivity to tensor and axial-vector operators involving first-generation quarks, and discuss the complementarity of the spin-dependent and independent contributions to μ→e conversion.« less

Spin-dependent μ → e conversion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cirigliano, Vincenzo; Davidson, Sacha; Kuno, Yoshitaka

The experimental sensitivity to μ→e conversion on nuclei is expected to improve by four orders of magnitude in coming years. Here, we consider the impact of μ→e flavour-changing tensor and axial-vector four-fermion operators which couple to the spin of nucleons. Such operators, which have not previously been considered, contribute to μ→e conversion in three ways: in nuclei with spin they mediate a spin-dependent transition; in all nuclei they contribute to the coherent (A 2-enhanced) spin-independent conversion via finite recoil effects and via loop mixing with dipole, scalar, and vector operators. Furthermore, we estimate the spin-dependent rate in Aluminium (the targetmore » of the upcoming COMET and Mu2e experiments), show that the loop effects give the greatest sensitivity to tensor and axial-vector operators involving first-generation quarks, and discuss the complementarity of the spin-dependent and independent contributions to μ→e conversion.« less

Optical properties of β-BBO and potential for THz applications

NASA Astrophysics Data System (ADS)

Nikolaev, N. A.; Andreev, Yu. M.; Antsygin, V. D.; Bekker, T. B.; Ezhov, D. M.; Kokh, A. E.; Kokh, K. A.; Lanskii, G. V.; Mamrashev, A. A.; Svetlichnyi, V. A.

2018-01-01

The anisotropy of optical properties of high quality beta barium borate crystal (β-BaB2O4, β-BBO) was studied in the main transparency window by using classic spectroscopic methods and in the range of 0.2 - 2 THz by using THz time-domain spectroscopy. β-BBO crystals were grown by the top-seeded solution technique in a highly resistive furnace with a heat field of 3-fold axis symmetry. At room temperature (RT), absorption coefficient in the maximal transparency window in grown crystals did not exceed 0.05 cm-1. Strong absorption anisotropy was observed in 3 - 5 μm and the THz range. At 1 THz absorption coefficients for e and o wave were, respectively, 7 cm-1 and 21 cm-1 at RT; 2 cm-1 and 10 cm-1 at 81 K. At the most attractive for out-of-door applications range < 0.4 THz the absorption coefficient is found to be very low: below 0.2 cm-1 at RT and 1 cm-1 at 81 K. Refractive indices dispersions measured by THz-TDS were approximated in the form of Sellmeier equations. Birefringence is found quite large for phase matched difference frequency generation (DFG) or down-conversion into the THz range (THz-DFG) under near IR pump at RT and 81 K. Type II (oe-o and eo-o), and type I (ee-e) three wave interactions can be realized at RT. THz-DFG of Nd:YAG laser and KTP OPO can be realized by type II (oe-o) three-wave interaction. For selected spectral ranges of femtosecond Ti:Sapphire laser efficient phase matched and group velocity matched optical rectification can be realized by another two types of three wave interactions. Accounting other well-known attractive physical properties of β-BBO crystal, wide application in THz technique can be forecasted.

Dose conversion coefficients for electron exposure of the human eye lens

NASA Astrophysics Data System (ADS)

Behrens, R.; Dietze, G.; Zankl, M.

2009-07-01

Recent epidemiological studies suggest a rather low dose threshold (below 0.5 Gy) for the induction of a cataract of the eye lens. Some other studies even assume that there is no threshold at all. Therefore, protection measures have to be optimized and current dose limits for the eye lens may be reduced in the future. Two questions arise from this situation: first, which dose quantity is related to the risk of developing a cataract, and second, which personal dose equivalent quantity is appropriate for monitoring this dose quantity. While the dose equivalent quantity Hp(0.07) has often been seen as being sufficiently accurate for monitoring the dose to the lens of the eye, this would be questionable in the case when the dose limits were reduced and, thus, it may be necessary to generally use the dose equivalent quantity Hp(3) for this purpose. The basis for a decision, however, must be the knowledge of accurate conversion coefficients from fluence to equivalent dose to the lens. This is especially important for low-penetrating radiation, for example, electrons. Formerly published values of conversion coefficients are based on quite simple models of the eye. In this paper, quite a sophisticated model of the eye including the inner structure of the lens was used for the calculations and precise conversion coefficients for electrons with energies between 0.2 MeV and 12 MeV, and for angles of radiation incidence between 0° and 45° are presented. Compared to the values adopted in 1996 by the International Commission on Radiological Protection (ICRP), the new values are up to 1000 times smaller for electron energies below 1 MeV, nearly equal at 1 MeV and above 4 MeV, and by a factor of 1.5 larger at about 1.5 MeV electron energy.

Dose conversion coefficients for electron exposure of the human eye lens.

PubMed

Behrens, R; Dietze, G; Zankl, M

2009-07-07

Recent epidemiological studies suggest a rather low dose threshold (below 0.5 Gy) for the induction of a cataract of the eye lens. Some other studies even assume that there is no threshold at all. Therefore, protection measures have to be optimized and current dose limits for the eye lens may be reduced in the future. Two questions arise from this situation: first, which dose quantity is related to the risk of developing a cataract, and second, which personal dose equivalent quantity is appropriate for monitoring this dose quantity. While the dose equivalent quantity H(p)(0.07) has often been seen as being sufficiently accurate for monitoring the dose to the lens of the eye, this would be questionable in the case when the dose limits were reduced and, thus, it may be necessary to generally use the dose equivalent quantity H(p)(3) for this purpose. The basis for a decision, however, must be the knowledge of accurate conversion coefficients from fluence to equivalent dose to the lens. This is especially important for low-penetrating radiation, for example, electrons. Formerly published values of conversion coefficients are based on quite simple models of the eye. In this paper, quite a sophisticated model of the eye including the inner structure of the lens was used for the calculations and precise conversion coefficients for electrons with energies between 0.2 MeV and 12 MeV, and for angles of radiation incidence between 0 degrees and 45 degrees are presented. Compared to the values adopted in 1996 by the International Commission on Radiological Protection (ICRP), the new values are up to 1000 times smaller for electron energies below 1 MeV, nearly equal at 1 MeV and above 4 MeV, and by a factor of 1.5 larger at about 1.5 MeV electron energy.

Octupole Correlations in THORIUM-225

NASA Astrophysics Data System (ADS)

Hughes, John Rhys

Available from UMI in association with The British Library. The nuclear structure of ^{225 }Th has been studied using the reaction ^{226}Ra(alpha,5n) ^{225}Th at a beam energy of 50 MeV. In-beam gamma-gamma , e^{-}-n, e ^{-}-e^{-} and e^{-}- gamma coincidences have been measured, using the TESSA3 array at the Daresbury NSF and the Double Orange spectrometer at the University of Bonn Cyclotron. gamma-ray and electron energies and intensities, gamma-ray angular distribution ratios and electron subshell ratios and conversion coefficients have been used to establish a decay scheme up to spin (39/2) hbar and excitation energy E _{z} ~ 2.5 MeV. The decay scheme is found to be characterised by two Delta J = 1 rotational bands, and these are classified in terms of the simplex quantum number, s, which is expected to be conserved for an octupole nucleus. No band crossings are observed up to a rotational frequency of hbaromega ~ 0.21 and 0.18 MeV in the s = -i and +i bands, respectively. Parity doublets have been observed, with enhanced E1 transitions linking states of opposite parity. gamma -branching ratios have been measured and an average value of | Q_1/Q_2| = (0.51 +/- 0.06) times 10^{-3} fm^{-1} has been deduced. The results are compared with various calculations incorporating odd multiple degrees of freedom in the description of the nuclear shape.

Calculation of conversion coefficients using Chinese adult reference phantoms for air submersion and ground contamination.

PubMed

Lu, Wei; Qiu, Rui; Wu, Zhen; Li, Chunyan; Yang, Bo; Liu, Huan; Ren, Li; Li, Junli

2017-03-21

The effective and organ equivalent dose coefficients have been widely used to provide assessment of doses received by adult members of the public and by workers exposed to environmental radiation from nuclear facilities under normal or accidental situations. Advancements in phantom types, weighting factors, decay data, etc, have led to the publication of newer results in this regard. This paper presents a new set of conversion coefficients for air submersion and ground contamination (with the use of Geant4) for photons from 15 keV to 10 MeV using the Chinese and International Commission on Radiological Protection (ICRP) adult reference male and female phantoms. The radiation fields, except for energy spectrum at low energies, were validated by the data obtained from the Monte Carlo code YURI. The effective dose coefficients of monoenergetic photons, obtained for the ICRP adult reference phantoms, agree well with recently published data for air submersion and ground contamination with a plane source at a depth of 0.5 g cm -2 in soil, but an average difference of 36.5% is observed for ground surface contamination with the abovementioned radiation field. The average differences in organ equivalent dose coefficients between the Chinese and the ICRP adult reference phantoms are within 6% for most organs, but noticeable differences of up to 70% or even higher are found at photon energies below 30 keV under air submersion. The effective dose coefficients obtained with the Chinese adult reference phantoms are greater than those of the ICRP adult reference phantoms above 30 keV and 0.5 MeV for ground contamination and air submersion, respectively; the average differences from the Chinese adult reference phantoms are about 3.6% and 0.4% in the whole energy range with maximum differences of 31.8% and 27.6% at 15 keV for air submersion and ground contamination respectively. These differences are attributed to anatomical discrepancies in overlying tissue mass of an individual organ and the body mass between the Chinese and the ICRP adult reference phantoms. These monoenergetic photon conversion coefficients are subsequently used to evaluate radionuclides with decay data from ICRP publication 107.

Calculation of conversion coefficients using Chinese adult reference phantoms for air submersion and ground contamination

NASA Astrophysics Data System (ADS)

Lu, Wei; Qiu, Rui; Wu, Zhen; Li, Chunyan; Yang, Bo; Liu, Huan; Ren, Li; Li, Junli

2017-03-01

The effective and organ equivalent dose coefficients have been widely used to provide assessment of doses received by adult members of the public and by workers exposed to environmental radiation from nuclear facilities under normal or accidental situations. Advancements in phantom types, weighting factors, decay data, etc, have led to the publication of newer results in this regard. This paper presents a new set of conversion coefficients for air submersion and ground contamination (with the use of Geant4) for photons from 15 keV to 10 MeV using the Chinese and International Commission on Radiological Protection (ICRP) adult reference male and female phantoms. The radiation fields, except for energy spectrum at low energies, were validated by the data obtained from the Monte Carlo code YURI. The effective dose coefficients of monoenergetic photons, obtained for the ICRP adult reference phantoms, agree well with recently published data for air submersion and ground contamination with a plane source at a depth of 0.5 g cm-2 in soil, but an average difference of 36.5% is observed for ground surface contamination with the abovementioned radiation field. The average differences in organ equivalent dose coefficients between the Chinese and the ICRP adult reference phantoms are within 6% for most organs, but noticeable differences of up to 70% or even higher are found at photon energies below 30 keV under air submersion. The effective dose coefficients obtained with the Chinese adult reference phantoms are greater than those of the ICRP adult reference phantoms above 30 keV and 0.5 MeV for ground contamination and air submersion, respectively; the average differences from the Chinese adult reference phantoms are about 3.6% and 0.4% in the whole energy range with maximum differences of 31.8% and 27.6% at 15 keV for air submersion and ground contamination respectively. These differences are attributed to anatomical discrepancies in overlying tissue mass of an individual organ and the body mass between the Chinese and the ICRP adult reference phantoms. These monoenergetic photon conversion coefficients are subsequently used to evaluate radionuclides with decay data from ICRP publication 107.

Modelling of plasma-based dry reforming: how do uncertainties in the input data affect the calculation results?

NASA Astrophysics Data System (ADS)

Wang, Weizong; Berthelot, Antonin; Zhang, Quanzhi; Bogaerts, Annemie

2018-05-01

One of the main issues in plasma chemistry modeling is that the cross sections and rate coefficients are subject to uncertainties, which yields uncertainties in the modeling results and hence hinders the predictive capabilities. In this paper, we reveal the impact of these uncertainties on the model predictions of plasma-based dry reforming in a dielectric barrier discharge. For this purpose, we performed a detailed uncertainty analysis and sensitivity study. 2000 different combinations of rate coefficients, based on the uncertainty from a log-normal distribution, are used to predict the uncertainties in the model output. The uncertainties in the electron density and electron temperature are around 11% and 8% at the maximum of the power deposition for a 70% confidence level. Still, this can have a major effect on the electron impact rates and hence on the calculated conversions of CO2 and CH4, as well as on the selectivities of CO and H2. For the CO2 and CH4 conversion, we obtain uncertainties of 24% and 33%, respectively. For the CO and H2 selectivity, the corresponding uncertainties are 28% and 14%, respectively. We also identify which reactions contribute most to the uncertainty in the model predictions. In order to improve the accuracy and reliability of plasma chemistry models, we recommend using only verified rate coefficients, and we point out the need for dedicated verification experiments.

Density conversion factor determined using a cone-beam computed tomography unit NewTom QR-DVT 9000.

PubMed

Lagravère, M O; Fang, Y; Carey, J; Toogood, R W; Packota, G V; Major, P W

2006-11-01

The purpose of this study was to determine a conversion coefficient for Hounsfield Units (HU) to material density (g cm(-3)) obtained from cone-beam computed tomography (CBCT-NewTom QR-DVT 9000) data. Six cylindrical models of materials with different densities were made and scanned using the NewTom QR-DVT 9000 Volume Scanner. The raw data were converted into DICOM format and analysed using Merge eFilm and AMIRA to determine the HU of different areas of the models. There was no significant difference (P = 0.846) between the HU given by each piece of software. A linear regression was performed using the density, rho (g cm(-3)), as the dependent variable in terms of the HU (H). The regression equation obtained was rho = 0.002H-0.381 with an R2 value of 0.986. The standard error of the estimation is 27.104 HU in the case of the Hounsfield Units and 0.064 g cm(-3) in the case of density. CBCT provides an effective option for determination of material density expressed as Hounsfield Units.

AIR KERMA TO Hp(3) CONVERSION COEFFICIENTS FOR IEC 61267 RQR X-RAY RADIATION QUALITIES: APPLICATION TO DOSE MONITORING OF THE LENS OF THE EYE IN MEDICAL DIAGNOSTICS.

PubMed

Principi, S; Guardiola, C; Duch, M A; Ginjaume, M

2016-09-01

Recent studies highlight the fact that the new eye lens dose limit can be exceeded in interventional radiology procedures and that eye lens monitoring could be required for these workers. The recommended operational quantity for monitoring of eye lens exposure is the personal dose equivalent at 3 mm depth Hp(3) (ICRU 51). However, there are no available conversion coefficients in international standards, while in the literature coefficients have only been calculated for monoenergetic beams and for ISO 4037-1 X-ray qualities. The aim of this article is to provide air kerma to Hp(3) conversion coefficients for a cylindrical phantom made of ICRU-4 elements tissue-equivalent material for RQR radiation qualities (IEC-61267) from 40 to 120 kV and for angles of incidence from 0 to 180°, which are characteristic of medical workplace. Analytic calculations using interpolation techniques and Monte Carlo modelling have been compared. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Precise Measurement of αK for the 39.76-keV E3 transition in 103Rh: Further Test of Internal Conversion Theory

NASA Astrophysics Data System (ADS)

Bryant, Justin; Park, Hyo In; Nica, Ninel; Iacob, Victor; Hardy, John

2017-09-01

We have extended our series of precision measurements of internal conversion coefficients (ICC) to include the 39.76-keV, E3 transition in 103Rh. Our goal has been to test the Dirac-Fock ICC calculations, specifically with respect to the role of the atomic vacancy created in the conversion process. We prepared a sample from pure (natural) ruthenium chloride by converting the sample to ruthenium oxide, electrochemically depositing it on an aluminum backing, and subsequently activating it with thermal neutrons at the Texas A&M TRIGA reactor for 20 hours. Decay spectra were then recorded for roughly 120 hours with a HPGe detector that has been precisely efficiency calibrated (+/-.15% relative precision). In the acquired spectra, all impurities were identified and corrected for accordingly. A program was written using the ROOT framework developed by CERN to extract the area of the 39.76-keV gamma-ray peak from 103Rh, which partially overlapped the Kα x-ray peaks from a 153Gd impurity. From the ratio of the 39.76-keV peak to the Ruthenium K x rays, we determined a preliminary value for the ICC: αk(39.76) =134.6(19). This result agrees well with the theoretical calculation including the atomic vacancy, 135.2, and disagrees with the calculation excluding the vacancy, 127.4. This is consistent with our previous measurements, indicating that the atomic vacancy must be taken into account. Thanks to the NSF, DOE and Welch Foundation.

Refractive index and extinction coefficient of NH2CH  =  NH2PbI3 perovskite photovoltaic material.

PubMed

Xie, Ziang; Sun, Shuren; Yan, Yu; Zhang, Lili; Hou, Ruixiang; Tian, Fuyang; Qin, G G

2017-06-21

Very recently, the NH 2 CH  =  NH 2 PbI 3 (FAPbI 3 ) perovskite material has attracted considerable attention in fabricating solar cells (SCs). For a photovoltaic material, its refractive index and extinction coefficient, n(λ) and k(λ), as functions of λ, are important to study its optical properties and to estimate the power conversion efficiency potential for the SCs made of it. As far as we know, to date there has been no reports of n(λ) and k(λ) for FAPbI 3 material. In this article, with spectroscopic ellipsometry (SE) measurements, the n(λ) and k(λ), as well as E g   =  1.45 eV for FAPbI 3 , are acquired. The fast deposition crystallization (FDC) procedure combined with the slowed down annealing (SDA) process is applied to fabricate smooth and uniform FAPbI 3 film on quartz substrate. Several kinds of organic solvents were tried as the second solvent in the FDC procedure, and it is found that when petroleum ether is used, the smallest surface roughness and good FAPbI 3 material purity of the FAPbI 3 film can be acquired. The k(λ) results for FAPbI 3 obtained by SE, calculated from the n(λ) using the Kramers-Kronig relationship, by absorbance, and by first-principles calculations, are compared. The n(λ) and k(λ) for FAPbI 3 are also compared with those for CH 3 NH 3 PbI 3 , GaAs and c-Si.

Refractive index and extinction coefficient of NH2CH  =  NH2PbI3 perovskite photovoltaic material

NASA Astrophysics Data System (ADS)

Xie, Ziang; Sun, Shuren; Yan, Yu; Zhang, Lili; Hou, Ruixiang; Tian, Fuyang; Qin, G. G.

2017-06-01

Very recently, the NH2CH  =  NH2PbI3 (FAPbI3) perovskite material has attracted considerable attention in fabricating solar cells (SCs). For a photovoltaic material, its refractive index and extinction coefficient, n(λ) and k(λ), as functions of λ, are important to study its optical properties and to estimate the power conversion efficiency potential for the SCs made of it. As far as we know, to date there has been no reports of n(λ) and k(λ) for FAPbI3 material. In this article, with spectroscopic ellipsometry (SE) measurements, the n(λ) and k(λ), as well as E g  =  1.45 eV for FAPbI3, are acquired. The fast deposition crystallization (FDC) procedure combined with the slowed down annealing (SDA) process is applied to fabricate smooth and uniform FAPbI3 film on quartz substrate. Several kinds of organic solvents were tried as the second solvent in the FDC procedure, and it is found that when petroleum ether is used, the smallest surface roughness and good FAPbI3 material purity of the FAPbI3 film can be acquired. The k(λ) results for FAPbI3 obtained by SE, calculated from the n(λ) using the Kramers-Kronig relationship, by absorbance, and by first-principles calculations, are compared. The n(λ) and k(λ) for FAPbI3 are also compared with those for CH3NH3PbI3, GaAs and c-Si.

SO2 Initiates the Efficient Conversion of NO2 to HONO on MgO Surface.

PubMed

Ma, Qingxin; Wang, Tao; Liu, Chang; He, Hong; Wang, Zhe; Wang, Weihao; Liang, Yutong

2017-04-04

Nitrous acid (HONO) is an important source of hydroxyl radical (OH) that determines the fate of many chemically active and climate relevant trace gases. However, the sources and the formation mechanisms of HONO remain poorly understood. In this study, the effect of SO 2 on the heterogeneous reactions of NO 2 on MgO as a mineral dust surrogate was investigated. The reactivity of MgO to NO 2 is weak, while coexisting SO 2 can increase the uptake coefficients of NO 2 on MgO by 2-3 orders of magnitude. The uptake coefficients of NO 2 on SO 2 -aged MgO are independent of NO 2 concentrations in the range of 20-160 ppbv and relative humidity (0-70%RH). The reaction mechanism was demonstrated to be a redox reaction between NO 2 and surface sulfite. In the presence of SO 2 , NO 2 was reduced to nitrite under dry conditions, which could be further converted to gas-phase HONO in humid conditions. These results suggest that the reductive effect of SO 2 on the heterogeneous conversion of NO 2 to HONO may have a significant contribution to the unknown sources of HONO observed in polluted areas (for example, in China).

Decouple electronic and phononic transport in nanotwinned structures: a new strategy for enhancing the figure-of-merit of thermoelectrics.

PubMed

Zhou, Yanguang; Gong, Xiaojing; Xu, Ben; Hu, Ming

2017-07-20

Thermoelectric (TE) materials manifest themselves to enable direct conversion of temperature differences to electric power and vice versa. Though remarkable advances have been achieved in the past decades for various TE systems, the energy conversion efficiency of TE devices, which is characterized by a dimensionless figure-of-merit (ZT = S 2 σT/(κ el + κ ph )), generally remains a poor factor that severely limits TE devices' competitiveness and range of employment. The bottleneck for substantially boosting the ZT coefficient lies in the strong interdependence of the physical parameters involved in electronic (S and σ, and κ el ) and phononic (κ ph ) transport. Herein, we propose a new strategy of incorporating nanotwinned structures to decouple electronic and phononic transport. Combining the new concept of nanotwinned structures with the previously widely used nanocrystalline approach, the power factor of the nanotwin-nanocrystalline Si heterostructures is enhanced by 120% compared to that of bulk crystalline Si, while the lattice thermal conductivity is reduced to a level well below the amorphous limit, yielding a theoretical limit of 0.52 and 0.9 for ZT coefficient at room temperature and 1100 K, respectively. This value is almost two orders of magnitude larger than that for bulk Si and twice that for polycrystalline Si. Even for the experimentally obtained nanotwin-nanocrystalline heterostructures (e.g. grain size of 5 nm), the ZT coefficient can be as high as 0.26 at room temperature and 0.7 at 1100 K, which is the highest ZT value among all Si-based bulk nanostructures found thus far. Such substantial improvement stems from two aspects: (1) the improvement in the power factor is caused due to an increase in the Seebeck coefficient (degeneracy of the band valley) and the enhancement of electrical conductivity (the reduction of the effective band mass) and (2) the significant reduction of the lattice thermal conductivity is mainly caused due to the extremely strong phonon-grain boundary and phonon-twin boundary scattering. Our results suggest that nanotwinned structures are excellent building blocks for enhancing TE performance in diamond-like semiconductors, and our study provides a new strategy for the innovative development of other TE materials.

Mean glandular dose to patients from stereotactic breast biopsy procedures.

PubMed

Paixão, Lucas; Chevalier, Margarita; Hurtado-Romero, Antonio E; Garayoa, Julia

2018-06-07

The aim of this work is to study the radiation doses delivered to a group of patients that underwent a stereotactic breast biopsy (SBB) procedure. Mean glandular doses (MGD) were estimated from the air-kerma measured at the breast surface entrance multiplying by specific conversion coefficients (DgN) that were estimated using Monte Carlo simulations. DgN were calculated for the 0º and ±15º projections used in SBB and for the particular beam quality. Data on 61 patients were collected showing that a typical SBB procedure is composed by 10 images. MGD was on average (4 ± 2) mGy with (0.38 ± 0.06) mGy per image. The use of specific conversion coefficients instead of typical DgN for mammography/tomosynthesis yields to obtain MGD values for SBB that are around a 65% lower on average. © 2018 Institute of Physics and Engineering in Medicine.

Nernst and Seebeck effects in HgTe/CdTe topological insulator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yuan; Song, Juntao; Li, Yu-Xian, E-mail: yxli@mail.hebtu.edu.cn

2015-03-28

The Seebeck and Nernst effects in HgTe/CdTe quantum wells are studied using the tight-binding Hamiltonian and the nonequilibrium Green's function method. The Seebeck coefficient, S{sub c}, and the Nernst coefficient, N{sub c}, oscillate as a function of E{sub F}, where E{sub F} is the Fermi energy. The Seebeck coefficient shows peaks when the Fermi energy crosses the discrete transverse channels, and the height of the nth peak of the S{sub c} is [ln2/(1/2 +|n|)] for E{sub F} > 0. For the case E{sub F} < 0, the values of the peaks are negative, but the absolute values of the first five peaks are themore » same as those for E{sub F} > 0. The 6th peak of S{sub c} reaches the value [ln2/1.35] due to a higher density of states. When a magnetic field is applied, the Nernst coefficient appears. However, the values of the peaks for N{sub c} are all positive. For a weak magnetic field, the temperature suppresses the oscillation of the Seebeck and Nernst coefficients but increases their magnitude. For a large magnetic field, because of the highly degenerate Landau levels, the peaks of the Seebeck coefficient at position E{sub F}=−12, 10, 28meV, and Nernst coefficient at E{sub F}=−7, 10meV are robust against the temperature.« less

Water-soluble drug partitioning and adsorption in HEMA/MAA hydrogels.

PubMed

Dursch, Thomas J; Taylor, Nicole O; Liu, David E; Wu, Rong Y; Prausnitz, John M; Radke, Clayton J

2014-01-01

Two-photon confocal microscopy and back extraction with UV/Vis-absorption spectrophotometry quantify equilibrium partition coefficients, k, for six prototypical drugs in five soft-contact-lens-material hydrogels over a range of water contents from 40 to 92%. Partition coefficients were obtained for acetazolamide, caffeine, hydrocortisone, Oregon Green 488, sodium fluorescein, and theophylline in 2-hydroxyethyl methacrylate/methacrylic acid (HEMA/MAA, pKa≈5.2) copolymer hydrogels as functions of composition, aqueous pH (2 and 7.4), and salinity. At pH 2, the hydrogels are nonionic, whereas at pH 7.4, hydrogels are anionic due to MAA ionization. Solute adsorption on and nonspecific electrostatic interaction with the polymer matrix are pronounced. To express deviation from ideal partitioning, we define an enhancement or exclusion factor, E ≡ k/φ1, where φ1 is hydrogel water volume fraction. All solutes exhibit E > 1 in 100 wt % HEMA hydrogels owing to strong specific adsorption to HEMA strands. For all solutes, E significantly decreases upon incorporation of anionic MAA into the hydrogel due to lack of adsorption onto charged MAA moieties. For dianionic sodium fluorescein and Oregon Green 488, and partially ionized monoanionic acetazolamide at pH 7.4, however, the decrease in E is more severe than that for similar-sized nonionic solutes. Conversely, at pH 2, E generally increases with addition of the nonionic MAA copolymer due to strong preferential adsorption to the uncharged carboxylic-acid group of MAA. For all cases, we quantitatively predict enhancement factors for the six drugs using only independently obtained parameters. In dilute solution for solute i, Ei is conveniently expressed as a product of individual enhancement factors for size exclusion (Ei(ex)), electrostatic interaction (Ei(el)), and specific adsorption (Ei(ad)):Ei≡Ei(ex)Ei(el)Ei(ad). To obtain the individual enhancement factors, we employ an extended Ogston mesh-size distribution for Ei(ex); Donnan equilibrium for Ei(el); and Henry's law characterizing specific adsorption to the polymer chains for Ei(ad). Predicted enhancement factors are in excellent agreement with experiment. Copyright © 2013 Elsevier Ltd. All rights reserved.

Involvement of cytosolic NAD+ glycohydrolase in cyclic ADP-ribose metabolism.

PubMed

Matsumura, N; Tanuma, S

1998-12-18

The NAD+ glycohydrolase homogeneously purified from bovine brain cytosol was found to catalyze the synthesis and hydrolysis of cyclic ADP-ribose (cADPR). Although the formation of cADPR from NAD+ does not exceed about 2% of the reaction products, the cyclase activity is clearly evidenced by its conversion of NGD+ to cyclic GDP-ribose (cGDPR), which cannot be hydrolyzed to GDPR. Importantly, a steep increase in cADPR hydrolytic activity was observed at cADPR concentrations above 60 microM, which could be reproduced on a Hill curve with a Hill coefficient of 2. Thus, the allosteric binding of cADPR to the NAD+ glycohydrolase (E) molecule promotes the hydrolysis of cADPR. These results suggest that NAD+ hydrolysis to ADPR and nicotinamide catalyzed by the NAD+ glycohydrolase occurs through the formation of a cADPR. E. cADP-ribosyl complex. The low production of cADPR by NAD+ glycohydrolase compared with invertebrate ADP-ribosyl cyclase is believed to be attributable to the fast hydrolysis of cADPR by the allosteric effect of cADPR bound to the same enzyme that produces it. Copyright 1998 Academic Press.

Monte Carlo calculation of the neutron dose to a fetus at commercial flight altitudes

NASA Astrophysics Data System (ADS)

Alves, M. C.; Galeano, D. C.; Santos, W. S.; Hunt, John G.; d'Errico, Francesco; Souza, S. O.; de Carvalho Júnior, A. B.

2017-11-01

Aircrew members are exposed to primary cosmic rays as well as to secondary radiations from the interaction of cosmic rays with the atmosphere and with the aircraft. The radiation field at flight altitudes comprises neutrons, protons, electrons, positrons, photons, muons and pions. Generally, 50% of the effective dose to airplane passengers is due to neutrons. Care must be taken especially with pregnant aircrew members and frequent fliers so that the equivalent dose to the fetus will not exceed prescribed limits during pregnancy (1 mSv according to ICRP, and 5 mSv according to NCRP). Therefore, it is necessary to evaluate the equivalent dose to a fetus in the maternal womb. Up to now, the equivalent dose rate to a fetus at commercial flight altitudes was obtained using stylized pregnant-female phantom models. The aim of this study was calculating neutron fluence to dose conversion coefficients for a fetus of six months of gestation age using a new, realistic pregnant-female mesh-phantom. The equivalent dose rate to a fetus during an intercontinental flight was also calculated by folding our conversion coefficients with published spectral neutron flux data. The calculated equivalent dose rate to the fetus was 2.35 μSv.h-1, that is 1.5 times higher than equivalent dose rates reported in the literature. The neutron fluence to dose conversion coefficients for the fetus calculated in this study were 2.7, 3.1 and 3.9 times higher than those from previous studies using fetus models of 3, 6 and 9 months of gestation age, respectively. The differences between our study and data from the literature highlight the importance of using more realistic anthropomorphic phantoms to estimate doses to a fetus in pregnant aircrew members.

High-yield conversion of (R)-2-octanol from the corresponding racemate by stereoinversion using Candida rugosa.

PubMed

Nie, Yao; Xu, Yan; Qing Mu, Xiao; Tang, Yan; Jiang, Juan; Hao Sun, Zhi

2005-01-01

Whole cells of Candida rugosa catalyzed the conversion of (R)-2-octanol from the corresponding racemate with the optical purity of 97% e.e. and yield of 92% in 10 h. The product was formed through a stereoinversion involving enantioselective oxidation and asymmetric reduction with 2-octanone as the intermediate.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chakraborty, S.; Izaguirre, I.; Raffelt, G.G.

Neutrino-neutrino refraction in dense media can cause self-induced flavor conversion triggered by collective run-away modes of the interacting flavor oscillators. The growth rates were usually found to be of order a typical vacuum oscillation frequency Δ m{sup 2}/2E. However, even in the simple case of a ν{sub e} beam interacting with an opposite-moving ν-bar {sub e} beam, and allowing for spatial inhomogeneities, the growth rate of the fastest-growing Fourier mode is of order μ=√2 G{sub F} n{sub ν}, a typical ν–ν interaction energy. This growth rate is much larger than the vacuum oscillation frequency and gives rise to flavor conversion on a muchmore » shorter time scale. This phenomenon of 'fast flavor conversion' occurs even for vanishing Δ m{sup 2}/2E and thus does not depend on energy, but only on the angle distributions. Moreover, it does not require neutrinos to mix or to have masses, except perhaps for providing seed disturbances. We also construct a simple homogeneous example consisting of intersecting beams and study a schematic supernova model proposed by Ray Sawyer, where ν{sub e} and ν-bar {sub e} emerge with different zenith-angle distributions, the key ingredient for fast flavor conversion. What happens in realistic astrophysical scenarios remains to be understood.« less

Properties of γ -decaying isomers and isomeric ratios in the 100Sn region

NASA Astrophysics Data System (ADS)

Park, J.; Krücken, R.; Lubos, D.; Gernhäuser, R.; Lewitowicz, M.; Nishimura, S.; Ahn, D. S.; Baba, H.; Blank, B.; Blazhev, A.; Boutachkov, P.; Browne, F.; Čeliković, I.; de France, G.; Doornenbal, P.; Faestermann, T.; Fang, Y.; Fukuda, N.; Giovinazzo, J.; Goel, N.; Górska, M.; Grawe, H.; Ilieva, S.; Inabe, N.; Isobe, T.; Jungclaus, A.; Kameda, D.; Kim, G. D.; Kim, Y.-K.; Kojouharov, I.; Kubo, T.; Kurz, N.; Lorusso, G.; Moschner, K.; Murai, D.; Nishizuka, I.; Patel, Z.; Rajabali, M. M.; Rice, S.; Sakurai, H.; Schaffner, H.; Shimizu, Y.; Sinclair, L.; Söderström, P.-A.; Steiger, K.; Sumikama, T.; Suzuki, H.; Takeda, H.; Wang, Z.; Watanabe, H.; Wu, J.; Xu, Z. Y.

2017-10-01

Half-lives and energies of γ rays emitted in the decay of isomeric states of nuclei in the vicinity of the doubly magic 100Sn were measured in a decay spectroscopy experiment at Rikagaku Kenkyusho (The Institute of Physical and Chemical Research) of Japan Nishina Center. The measured half-lives, some with improved precision, are consistent with literature values. Three new results include a 55-keV E 2 γ ray from a new (4+) isomer with T1 /2=0.23 (6 ) μ s in 92Rh, a 44-keV E 2 γ ray from the (15+) isomer in 96Ag, and T1 /2(6+) =13 (2 ) ns in 98Cd. Shell-model calculations of electromagnetic transition strengths in the (p1 /2,g9 /2) model space agree with the experimental results. In addition, experimental isomeric ratios were compared to the theoretical predictions derived with an abrasion-ablation model and the sharp cutoff model. The results agreed within a factor of 2 for most isomers. From the nonobservation of time-delayed γ rays in 100Sn, new constraints on the T1 /2, γ -ray energy, and internal conversion coefficients are proposed for the hypothetical isomer in 100Sn.

Phosphotyrosine as a substrate of acid and alkaline phosphatases.

PubMed

Apostoł, I; Kuciel, R; Wasylewska, E; Ostrowski, W S

1985-01-01

A new spectrophotometric method for following dephosphorylation of phosphotyrosine has been described. The absorption spectra of phosphotyrosine and tyrosine were plotted over the pH range from 3 to 9. The change in absorbance accompanying the conversion of phosphotyrosine to tyrosine was the greatest at 286 nm. The difference absorption coefficients were calculated for several pH values. Dephosphorylation of phosphotyrosine by acid phosphatases from human prostate gland, from wheat germ and potatoes obeys the Michaelis-Menten equation, whereas alkaline phosphatases calf intestine and E. coli are inhibited by excess of substrate.

Synthesis and characterization of (Sn,Zn)O alloys

DOE PAGES

Bikowski, Andre; Holder, Aaron; Peng, Haowei; ...

2016-09-29

SnO exhibits electrical properties that render it promising for solar energy conversion applications, but it also has a strongly indirect band gap. Recent theoretical calculations predict that this disadvantage can be mitigated by isovalent alloying with other group-II oxides such as ZnO. Here, we synthesized new metastable isovalent (Sn,Zn)O alloy thin films by combinatorial reactive co-sputtering and characterized their structural, optical and electrical properties. The alloying of ZnO into SnO leads to a change of the valence state of the tin from Sn 0 via Sn 2+ to Sn 4+, which can be counteracted by reducing the oxygen partial pressuremore » during the deposition. The optical characterization of the smooth <10 at. % Sn 1-xZn xO thin films showed an increase in the absorption coefficient in the range from 1 to 2 eV, which is consistent with the theoretical predictions for the isovalent alloying. However, the experimentally observed alloying effect may be convoluted with the effect of local variations of the Sn oxidation state. As a result, this effect would have to be minimized to improve the (Sn,Zn)O optical and electrical properties for their use as absorbers in solar energy conversion applications.« less

Ortho-para H₂ conversion by proton exchange at low temperature: an accurate quantum mechanical study.

PubMed

Honvault, P; Jorfi, M; González-Lezana, T; Faure, A; Pagani, L

2011-07-08

We report extensive, accurate fully quantum, time-independent calculations of cross sections at low collision energies, and rate coefficients at low temperatures for the H⁺ + H₂(v = 0, j) → H⁺ + H₂(v = 0, j') reaction. Different transitions are considered, especially the ortho-para conversion (j = 1 → j' = 0) which is of key importance in astrophysics. This conversion process appears to be very efficient and dominant at low temperature, with a rate coefficient of 4.15 × 10⁻¹⁰ cm³ molecule⁻¹ s⁻¹ at 10 K. The quantum mechanical results are also compared with statistical quantum predictions and the reaction is found to be statistical in the low temperature regime (T < 100 K).

Conversion of time-varying Stokes coefficients into mass anomalies at the Earth's surface considering the Earth's oblateness

NASA Astrophysics Data System (ADS)

Ditmar, Pavel

2018-02-01

Time-varying Stokes coefficients estimated from GRACE satellite data are routinely converted into mass anomalies at the Earth's surface with the expression proposed for that purpose by Wahr et al. (J Geophys Res 103(B12):30,205-30,229, 1998). However, the results obtained with it represent mass transport at the spherical surface of 6378 km radius. We show that the accuracy of such conversion may be insufficient, especially if the target area is located in a polar region and the signal-to-noise ratio is high. For instance, the peak values of mean linear trends in 2003-2015 estimated over Greenland and Amundsen Sea embayment of West Antarctica may be underestimated in this way by about 15%. As a solution, we propose an updated expression for the conversion of Stokes coefficients into mass anomalies. This expression is based on the assumptions that: (i) mass transport takes place at the reference ellipsoid and (ii) at each point of interest, the ellipsoidal surface is approximated by the sphere with a radius equal to the current radial distance from the Earth's center ("locally spherical approximation"). The updated expression is nearly as simple as the traditionally used one but reduces the inaccuracies of the conversion procedure by an order of magnitude. In addition, we remind the reader that the conversion expressions are defined in spherical (geocentric) coordinates. We demonstrate that the difference between mass anomalies computed in spherical and ellipsoidal (geodetic) coordinates may not be negligible, so that a conversion of geodetic colatitudes into geocentric ones should not be omitted.

Double-use linear polarization convertor using hybrid metamaterial based on VO2 phase transition in the terahertz region

NASA Astrophysics Data System (ADS)

Zou, Huanling; Xiao, Zhongyin; Li, Wei; Li, Chuan

2018-04-01

A number of polarization convertors based on metamaterials(MMs) have been investigated recently, but no one has proposed a high-efficiency linear polarization transformer both in transmission and reflection modes. Here, a bilayered MM embedded with vanadium dioxide (VO2) composed of a pair of sloping gold patches, bottom hybrid layer and a dielectric spacer is proposed as a double-use linear polarization convertor. It has been demonstrated numerically that this device has advantages of switching between transmission polarization conversion and reflection polarization conversion based on the phase transition of the VO2 film in the terahertz (THz) regime and the polarization conversion ratios (PCR) in both cases are higher than 90% in wide bands. The simulated linear polarization transmission/reflection coefficients and the surface current distributions give insight into the mechanism of the linear polarization conversions. Moreover, the physical mechanism of polarization sensitivity of the designed structure is investigated by the distributions of electric field. The proposed double-use linear polarization convertor shows great prospects in polarization imaging, and polarized light communications.

Calibration of diffuse correlation spectroscopy blood flow index with venous-occlusion diffuse optical spectroscopy in skeletal muscle

PubMed Central

Li, Zhe; Baker, Wesley B.; Parthasarathy, Ashwin B.; Ko, Tiffany S.; Wang, Detian; Schenkel, Steven; Durduran, Turgut; Li, Gang; Yodh, Arjun G.

2015-01-01

Abstract. We investigate and assess the utility of a simple scheme for continuous absolute blood flow monitoring based on diffuse correlation spectroscopy (DCS). The scheme calibrates DCS using venous-occlusion diffuse optical spectroscopy (VO-DOS) measurements of arm muscle tissue at a single time-point. A calibration coefficient (γ) for the arm is determined, permitting conversion of DCS blood flow indices to absolute blood flow units, and a study of healthy adults (N=10) is carried out to ascertain the variability of γ. The average DCS calibration coefficient for the right (i.e., dominant) arm was γ=(1.24±0.15)×108 (mL·100  mL−1·min−1)/(cm2/s). However, variability can be significant and is apparent in our site-to-site and day-to-day repeated measurements. The peak hyperemic blood flow overshoot relative to baseline resting flow was also studied following arm-cuff ischemia; excellent agreement between VO-DOS and DCS was found (R2=0.95, slope=0.94±0.07, mean difference=−0.10±0.45). Finally, we show that incorporation of subject-specific absolute optical properties significantly improves blood flow calibration accuracy. PMID:26720870

Radiometer offsets and count conversion coefficients for the Earth Radiation Budget Experiment (ERBE) spacecraft for the years 1987, 1988, and 1989

NASA Technical Reports Server (NTRS)

Paden, Jack; Pandey, Dhirendra K.; Stassi, Joseph C.; Wilson, Robert; Bolden, William; Thomas, Susan; Gibson, M. Alan

1993-01-01

This document contains a compendium of the ground and in-flight scanner and non-scanner offsets and count conversion (gain) coefficients used for the Earth Radiation Budget Experiment (ERBE) production processing of data from the ERBS satellite for the period from 1 January 1987 to 31 December 1989; for the NOAA-9 satellite, for the month of January 1987; and for the NOAA-10 satellite, for the period from 1 January 1987 to 31 May 1989.

On Association Coefficients for 2x2 Tables and Properties that Do Not Depend on the Marginal Distributions

ERIC Educational Resources Information Center

Warrens, Matthijs J.

2008-01-01

We discuss properties that association coefficients may have in general, e.g., zero value under statistical independence, and we examine coefficients for 2x2 tables with respect to these properties. Furthermore, we study a family of coefficients that are linear transformations of the observed proportion of agreement given the marginal…

TU-H-CAMPUS-IeP1-03: Comparison of Monte Carlo Simulation and Conversion Factor Based Method On Estimation of Effective Dose in Pediatric Patients Undergoing Interventional Cardiac Procedures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leung, K; Wong, M; Ng, Y

Purpose: Interventional cardiac procedures utilize frequent fluoroscopy and cineangiography, which impose considerable radiation risk to patients, especially pediatric patients. Accurate calculation of effective dose is important in order to estimate cancer risk over the rest of their lifetime. This study evaluates the difference in effective dose calculated by Monte Carlo simulation with those estimated by locally-derived conversion factors (CF-local) and by commonly quoted conversion factors from Karambatsakidou et al (CF-K). Methods: Effective dose (E),of 12 pediatric patients, age between 2.5–19 years old, who had undergone interventional cardiac procedures, were calculated using PCXMC-2.0 software. Tube spectrum, irradiation geometry, exposure parameters andmore » dose-area product (DAP) of each projection were included in the software calculation. Effective doses for each patient were also estimated by two Methods: 1) CF-local: conversion factor derived locally by generalizing results of 12 patients, multiplied by DAP of each patient gives E-local. 2) CF-K: selected factor from above-mentioned literature, multiplied by DAP of each patient gives E-K. Results: Mean of E, E-local and E-K were 16.01 mSv, 16.80 mSv and 22.25 mSv respectively. A deviation of −29.35% to +34.85% between E and E-local, while a greater deviation of −28.96% to +60.86% between E and EK were observed. E-K overestimated the effective dose for patients at age 7.5–19. Conclusion: Effective dose obtained by conversion factors is simple and quick to estimate radiation risk of pediatric patients. This study showed that estimation by CF-local may bear an error of 35% when compared with Monte Carlo calculation. If using conversion factors derived by other studies may result in an even greater error, of up to 60%, due to factors that are not catered for in the estimation, including patient size, projection angles, exposure parameters, tube filtration, etc. Users must be aware of these potential inaccuracies when simple conversion method is employed.« less

The Mu2e experiment at Fermilab: A search for lepton flavor violation

DOE PAGES

Pezzullo, Gianantonio

2017-05-04

The Mu2e experiment at Fermilab will search for the charged lepton flavor violating process of neutrino-less μ→e coherent conversion in the field of an aluminum nucleus. About 7 ∙ 10 17 muons, provided by a dedicated muon beam line in construction at Fermilab, will be stopped in 3 years in the aluminum target. The corresponding single event sensitivity will be 2.5∙10 $-$17 . Here in this paper a brief overview of the physics explored by the μ→e conversion is given, followed by a description of the Mu2e experimental apparatus and the expected detector performance.

Entropy-scaling laws for diffusion coefficients in liquid metals under high pressures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cao, Qi-Long, E-mail: qlcao@mail.ustc.edu.cn; Shao, Ju-Xiang; Wang, Fan-Hou, E-mail: eatonch@gmail.com

2015-04-07

Molecular dynamic simulations on the liquid copper and tungsten are used to investigate the empirical entropy-scaling laws D{sup *}=A exp(BS{sub ex}), proposed independently by Rosenfeld and Dzugutov for diffusion coefficient, under high pressure conditions. We show that the scaling laws hold rather well for them under high pressure conditions. Furthermore, both the original diffusion coefficients and the reduced diffusion coefficients exhibit an Arrhenius relationship D{sub M}=D{sub M}{sup 0} exp(−E{sub M}/K{sub B}T), (M=un,R,D) and the activation energy E{sub M} increases with increasing pressure, the diffusion pre-exponential factors (D{sub R}{sup 0} and D{sub D}{sup 0}) are nearly independent of the pressure and element. Themore » pair correlation entropy, S{sub 2}, depends linearly on the reciprocal temperature S{sub 2}=−E{sub S}/T, and the activation energy, E{sub S}, increases with increasing pressure. In particular, the ratios of the activation energies (E{sub un}, E{sub R}, and E{sub D}) obtained from diffusion coefficients to the activation energy, E{sub S}, obtained from the entropy keep constants in the whole pressure range. Therefore, the entropy-scaling laws for the diffusion coefficients and the Arrhenius law are linked via the temperature dependence of entropy.« less

Thermoelectric Properties of n-type SnSe Single Crystal

NASA Astrophysics Data System (ADS)

Nguyen, Phuong; Duong, Anh Tuan; Rhim, S. H.; Nguyen, Van Quang; Duong, Van Thiet; Shin, Yooleemi; Cho, Sunglae; Kwon, Suyong; Song, Jae Yong; Park, Hyun Min

Although thermoelectric materials are well known for their reliability and have been used for many years, even in the field of space engineering, their performance is quite small due to low energy conversion efficiency. Dimensionless figure of merit, ZT = S2. σ.T.κ-1 (where S, σ, T, κ are Seebeck coefficient, electrical conductivity, absolute temperature and thermal conductivity, respectively) is conveniently used to evaluate the conversion efficiency of a thermoelectric materials. Recently, the highest value of ZT to date has been reported for single crystal SnSe, ZT = 2.6 along the b axis of unit cell at 923 K. This temperature is rather high and the range of temperature for high reported ZT is quite narrow. Here we report an attempt to modify the thermoelectric properties of SnSe by using group V and VII as n-type dopant. A negative value of Seebeck coefficient was observed and the power factor reached a peak of 10 μW.K-2.cm-1 at around 600 K. The maximum n-type ZT was 0.57 at 650 K. We will discuss on dopant dependent thermoelectric properties of n-type SnSe single crystals.

Alpine radar conversion for LAWR

NASA Astrophysics Data System (ADS)

Savina, M.; Burlando, P.

2012-04-01

The Local Area Weather Radar (LAWR) is a ship-born weather radar system operating in X-band developed by the DHI Group to detect precipitation in urban areas. To date more than thirty units are installed in different settings around the world. A LAWR was also deployed in the Alps, at 3883 m a.s.l. on the Kl. Matterhorn (Valais, Switzerland). This was the highest LAWR of the world and it led to the development of an Alpine LAWR system that, besides featuring important technological improvements needed to withstand the severe Alpine conditions, required the development of a new Alpine Radar COnversion Model (ARCOM), which is the main focus of this contribution. The LAWR system is equipped with the original FURUNO fan-beam slotted antenna and the original logarithmic receiver, which limits the radar observations to the video signal (L) withour providing the reflectivity (Z). The beam is 0.95 deg wide and 20 deg high. It can detect precipitation to a max range of 60 km. In order to account for the limited availability of raw signal and information and the specific mountain set-up, the conversion model had to be developed differently from the state-of-the-art radar conversion technique used for this class of radars. In particular, the ARCOM is based on a model used to simulate a spatial dependent factor, hereafter called ACF, which is in turn function of parameters that take in account climatological conditions, also used in other conversion methods, but additionally accounting for local radar beam features and for orographic forcings such as the effective sampling power (sP), which is modelled by means of antenna pattern, geometric ground clutter and their interaction. The result is a conversion factor formulated to account for a range correction that is based on the increase of the sampling volume, partial beam blocking and local climatological conditions. The importance of the latter in this study is double with respect to the standard conversion technique for this class of radars, because it accounts for the large variability of hydrometeors reflectivity and vertical hydrometeors positioning (echo-top), which is strongly influenced by the high location of the radar. The ARCOM procedure is in addition embedded in a multistep quality control framework, which also includes the calibration on raingauge observations, and can be summarized as follow: 1) correction of both LAWR and raingauge observations for known errors (e.g. magnetron decay and heated-related water loss) 2) evaluation of the local Pearson's correlation coefficient (PCC) as estimator of the linear correlation between raingauge and LAWR observations (logarithmic receiver); 3) computation of the local ACF in the form of the local linear regression coefficient between raingauge and LAWR observations; 4) calibration of the ARCOM, i.e. definition of the parametrization able to reproduce the spatial variability of ACF as function of the local sP, being the PCCs used as weight in the calibration procedure. The resulting calibrated ARCOM finally allows, in any ungauged mountain spot, to convert LAWR observations into precipitation rate. The temporal and the spatial transferability of the ARCOM are evaluated via split-sample and a take-one-out cross validation. The results revealed good spatial transferability and a seasonal bias within 7%, thus opening new opportunities for local range distributed measurements of precipitation in mountain regions.

Fuel Economy and Emissions of a Vehicle Equipped with an Aftermarket Flexible-Fuel Conversion Kit

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thomas, John F; Huff, Shean P; West, Brian H

2012-04-01

The U.S. Environmental Protection Agency (EPA) grants Certificates of Conformity for alternative fuel conversion systems and also offers other forms of premarket registration of conversion kits for use in vehicles more than two model years old. Use of alternative fuels such as ethanol, natural gas, and propane are encouraged by the Energy Policy Act of 1992. Several original equipment manufacturers (OEMs) produce emissions-certified vehicles capable of using alternative fuels, and several alternative fuel conversion system manufacturers produce EPA-approved conversion systems for a variety of alternative fuels and vehicle types. To date, only one manufacturer (Flex Fuel U.S.) has received EPAmore » certifications for ethanol fuel (E85) conversion kits. This report details an independent evaluation of a vehicle with a legal installation of a Flex Fuel U.S. conversion kit. A 2006 Dodge Charger was baseline tested with ethanol-free certification gasoline (E0) and E20 (gasoline with 20 vol % ethanol), converted to flex-fuel operation via installation of a Flex Box Smart Kit from Flex Fuel U.S., and retested with E0, E20, E50, and E81. Test cycles included the Federal Test Procedure (FTP or city cycle), the highway fuel economy test (HFET), and the US06 test (aggressive driving test). Averaged test results show that the vehicle was emissions compliant on E0 in the OEM condition (before conversion) and compliant on all test fuels after conversion. Average nitrogen oxide (NOx) emissions exceeded the Tier 2/Bin 5 intermediate life NO{sub X} standard with E20 fuel in the OEM condition due to two of three test results exceeding this standard [note that E20 is not a legal fuel for non-flexible-fuel vehicles (non-FFVs)]. In addition, one E0 test result before conversion and one E20 test result after conversion exceeded the NOX standard, although the average result in these two cases was below the standard. Emissions of ethanol and acetaldehyde increased with increasing ethanol, while nonmethane organic gas and CO emissions remained relatively unchanged for all fuels and cycles. Higher fraction ethanol blends appeared to decrease NO{sub X} emissions on the FTP and HFET (after conversion). As expected, fuel economy (miles per gallon) decreased with increasing ethanol content in all cases.« less

Dose conversion coefficients for photon exposure of the human eye lens.

PubMed

Behrens, R; Dietze, G

2011-01-21

In recent years, several papers dealing with the eye lens dose have been published, because epidemiological studies implied that the induction of cataracts occurs even at eye lens doses of less than 500 mGy. Different questions were addressed: Which personal dose equivalent quantity is appropriate for monitoring the dose to the eye lens? Is a new definition of the dose quantity H(p)(3) based on a cylinder phantom to represent the human head necessary? Are current conversion coefficients from fluence to equivalent dose to the lens sufficiently accurate? To investigate the latter question, a realistic model of the eye including the inner structure of the lens was developed. Using this eye model, conversion coefficients for electrons have already been presented. In this paper, the same eye model-with the addition of the whole body-was used to calculate conversion coefficients from fluence (and air kerma) to equivalent dose to the lens for photon radiation from 5 keV to 10 MeV. Compared to the values adopted in 1996 by the International Commission on Radiological Protection (ICRP), the new values are similar between 40 keV and 1 MeV and lower by up to a factor of 5 and 7 for photon energies at about 10 keV and 10 MeV, respectively. Above 1 MeV, the new values (calculated without kerma approximation) should be applied in pure photon radiation fields, while the values adopted by the ICRP in 1996 (calculated with kerma approximation) should be applied in case a significant contribution from secondary electrons originating outside the body is present.

Dose conversion coefficients for photon exposure of the human eye lens

NASA Astrophysics Data System (ADS)

Behrens, R.; Dietze, G.

2011-01-01

In recent years, several papers dealing with the eye lens dose have been published, because epidemiological studies implied that the induction of cataracts occurs even at eye lens doses of less than 500 mGy. Different questions were addressed: Which personal dose equivalent quantity is appropriate for monitoring the dose to the eye lens? Is a new definition of the dose quantity Hp(3) based on a cylinder phantom to represent the human head necessary? Are current conversion coefficients from fluence to equivalent dose to the lens sufficiently accurate? To investigate the latter question, a realistic model of the eye including the inner structure of the lens was developed. Using this eye model, conversion coefficients for electrons have already been presented. In this paper, the same eye model—with the addition of the whole body—was used to calculate conversion coefficients from fluence (and air kerma) to equivalent dose to the lens for photon radiation from 5 keV to 10 MeV. Compared to the values adopted in 1996 by the International Commission on Radiological Protection (ICRP), the new values are similar between 40 keV and 1 MeV and lower by up to a factor of 5 and 7 for photon energies at about 10 keV and 10 MeV, respectively. Above 1 MeV, the new values (calculated without kerma approximation) should be applied in pure photon radiation fields, while the values adopted by the ICRP in 1996 (calculated with kerma approximation) should be applied in case a significant contribution from secondary electrons originating outside the body is present.

The conversion of exposures due to radon into the effective dose: the epidemiological approach.

PubMed

Beck, T R

2017-11-01

The risks and dose conversion coefficients for residential and occupational exposures due to radon were determined with applying the epidemiological risk models to ICRP representative populations. The dose conversion coefficient for residential radon was estimated with a value of 1.6 mSv year -1 per 100 Bq m -3 (3.6 mSv per WLM), which is significantly lower than the corresponding value derived from the biokinetic and dosimetric models. The dose conversion coefficient for occupational exposures with applying the risk models for miners was estimated with a value of 14 mSv per WLM, which is in good accordance with the results of the dosimetric models. To resolve the discrepancy regarding residential radon, the ICRP approaches for the determination of risks and doses were reviewed. It could be shown that ICRP overestimates the risk for lung cancer caused by residential radon. This can be attributed to a wrong population weighting of the radon-induced risks in its epidemiological approach. With the approach in this work, the average risks for lung cancer were determined, taking into account the age-specific risk contributions of all individuals in the population. As a result, a lower risk coefficient for residential radon was obtained. The results from the ICRP biokinetic and dosimetric models for both, the occupationally exposed working age population and the whole population exposed to residential radon, can be brought in better accordance with the corresponding results of the epidemiological approach, if the respective relative radiation detriments and a radiation-weighting factor for alpha particles of about ten are used.

CO2 diffusion in champagne wines: a molecular dynamics study.

PubMed

Perret, Alexandre; Bonhommeau, David A; Liger-Belair, Gérard; Cours, Thibaud; Alijah, Alexander

2014-02-20

Although diffusion is considered as the main physical process responsible for the nucleation and growth of carbon dioxide bubbles in sparkling beverages, the role of each type of molecule in the diffusion process remains unclear. In the present study, we have used the TIP5P and SPC/E water models to perform force field molecular dynamics simulations of CO2 molecules in water and in a water/ethanol mixture respecting Champagne wine proportions. CO2 diffusion coefficients were computed by applying the generalized Fick's law for the determination of multicomponent diffusion coefficients, a law that simplifies to the standard Fick's law in the case of champagnes. The CO2 diffusion coefficients obtained in pure water and water/ethanol mixtures composed of TIP5P water molecules were always found to exceed the coefficients obtained in mixtures composed of SPC/E water molecules, a trend that was attributed to a larger propensity of SPC/E water molecules to form hydrogen bonds. Despite the fact that the SPC/E model is more accurate than the TIP5P model to compute water self-diffusion and CO2 diffusion in pure water, the diffusion coefficients of CO2 molecules in the water/ethanol mixture are in much better agreement with the experimental values of 1.4 - 1.5 × 10(-9) m(2)/s obtained for Champagne wines when the TIP5P model is employed. This difference was deemed to rely on the larger propensity of SPC/E water molecules to maintain the hydrogen-bonded network between water molecules and form new hydrogen bonds with ethanol, although statistical issues cannot be completely excluded. The remarkable agreement between the theoretical CO2 diffusion coefficients obtained within the TIP5P water/ethanol mixture and the experimental data specific to Champagne wines makes us infer that the diffusion coefficient in these emblematic hydroalcoholic sparkling beverages is expected to remain roughly constant whathever their proportions in sugars, glycerol, or peptides.

HDRK-Man: a whole-body voxel model based on high-resolution color slice images of a Korean adult male cadaver

NASA Astrophysics Data System (ADS)

Kim, Chan Hyeong; Hyoun Choi, Sang; Jeong, Jong Hwi; Lee, Choonsik; Chung, Min Suk

2008-08-01

A Korean voxel model, named 'High-Definition Reference Korean-Man (HDRK-Man)', was constructed using high-resolution color photographic images that were obtained by serially sectioning the cadaver of a 33-year-old Korean adult male. The body height and weight, the skeletal mass and the dimensions of the individual organs and tissues were adjusted to the reference Korean data. The resulting model was then implemented into a Monte Carlo particle transport code, MCNPX, to calculate the dose conversion coefficients for the internal organs and tissues. The calculated values, overall, were reasonable in comparison with the values from other adult voxel models. HDRK-Man showed higher dose conversion coefficients than other models, due to the facts that HDRK-Man has a smaller torso and that the arms of HDRK-Man are shifted backward. The developed model is believed to adequately represent average Korean radiation workers and thus can be used for more accurate calculation of dose conversion coefficients for Korean radiation workers in the future.

Towards the reanalysis of void coefficients measurements at proteus for high conversion light water reactor lattices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hursin, M.; Koeberl, O.; Perret, G.

2012-07-01

High Conversion Light Water Reactors (HCLWR) allows a better usage of fuel resources thanks to a higher breeding ratio than standard LWR. Their uses together with the current fleet of LWR constitute a fuel cycle thoroughly studied in Japan and the US today. However, one of the issues related to HCLWR is their void reactivity coefficient (VRC), which can be positive. Accurate predictions of void reactivity coefficient in HCLWR conditions and their comparisons with representative experiments are therefore required. In this paper an inter comparison of modern codes and cross-section libraries is performed for a former Benchmark on Void Reactivitymore » Effect in PWRs conducted by the OECD/NEA. It shows an overview of the k-inf values and their associated VRC obtained for infinite lattice calculations with UO{sub 2} and highly enriched MOX fuel cells. The codes MCNPX2.5, TRIPOLI4.4 and CASMO-5 in conjunction with the libraries ENDF/B-VI.8, -VII.0, JEF-2.2 and JEFF-3.1 are used. A non-negligible spread of results for voided conditions is found for the high content MOX fuel. The spread of eigenvalues for the moderated and voided UO{sub 2} fuel are about 200 pcm and 700 pcm, respectively. The standard deviation for the VRCs for the UO{sub 2} fuel is about 0.7% while the one for the MOX fuel is about 13%. This work shows that an appropriate treatment of the unresolved resonance energy range is an important issue for the accurate determination of the void reactivity effect for HCLWR. A comparison to experimental results is needed to resolve the presented discrepancies. (authors)« less

Magnetron sputtering fabrication and photoelectric properties of WSe2 film solar cell device

NASA Astrophysics Data System (ADS)

Mao, Xu; Zou, Jianpeng; Li, Hongchao; Song, Zhengqi; He, Siru

2018-06-01

Tungsten diselenide (WSe2) films with different growing orientations exhibit diverse photoelectric properties. The WSe2 film with C-axis⊥substrate texture has been prepared and applied to thin-film solar cells. W nanofilms with a thickness of 270 nm were deposited onto the Mo bottom electrode and then heat-treated in selenium vapor to synthesize WSe2 films with a thickness of 1 μm. ZnO films were deposited onto WSe2 films to form a P-N junction and ITO films were deposited subsequently as the conductive layer. X-ray diffractometry, scanning electron microscopy and UV-vis-NIR spectro-analysis instrument were employed to analyze the phase composition, optical absorptivity and micromorphology of WSe2 films and the WSe2 solar cell device. WSe2 films exhibit excellent photoelectric performance with an optical absorption coefficient greater than 105 cm-1 across the visible spectrum. The calculated direct and indirect band gap of the WSe2 films is 1.48 eV and 1.25 eV, respectively. With the application of standard glass/Mo/WSe2/ZnO/ITO/Ag device structure, the open-circuit voltage of the battery device is 82 mV. The short-circuit current density is 2.98 mA/cm2 and the filling factor is 0.32. The photoelectric conversion efficiency of the WSe2 film solar cell device is 0.79%.

Efficient charge-spin conversion and magnetization switching through the Rashba effect at topological-insulator/Ag interfaces

NASA Astrophysics Data System (ADS)

Shi, Shuyuan; Wang, Aizhu; Wang, Yi; Ramaswamy, Rajagopalan; Shen, Lei; Moon, Jisoo; Zhu, Dapeng; Yu, Jiawei; Oh, Seongshik; Feng, Yuanping; Yang, Hyunsoo

2018-01-01

We report the observation of efficient charge-to-spin conversion in the three-dimensional topological insulator (TI) B i2S e3 and Ag bilayer by the spin-torque ferromagnetic resonance technique. The spin-orbit-torque ratio in the B i2S e3/Ag /CoFeB heterostructure shows a significant enhancement as the Ag thickness increases to ˜2 nm and reaches a value of 0.5 for 5 nm Ag, which is ˜3 times higher than that of B i2S e3/CoFeB at room temperature. The observation reveals the interfacial effect of B i2S e3/Ag exceeds that of the topological surface states (TSSs) in the B i2S e3 layer and plays a dominant role in the charge-to-spin conversion in the B i2S e3/Ag /CoFeB system. Based on first-principles calculations, we attribute our observation to the large Rashba splitting bands which wrap the TSS band and have the same net spin polarization direction as the TSS of B i2S e3 . Subsequently, we demonstrate Rashba-induced magnetization switching in B i2S e3/Ag /Py with a low current density of 5.8 ×105A /c m2 .

The dose from Compton backscatter screening.

PubMed

Rez, Peter; Metzger, Robert L; Mossman, Kenneth L

2011-04-01

Systems based on the detection of Compton backscattered X rays have been deployed for screening personnel for weapons and explosives. Similar principles are used for screening vehicles at border-crossing points. Based on well-established scattering cross sections and absorption coefficients in conjunction with reasonable estimates of the image contrast and resolution, the entrance skin dose and the dose at a depth of 1 cm can be calculated. The effective dose can be estimated using the same conversion coefficients as used to convert exposure measurements to the effective dose. It is shown that the effective dose is highly dependent on image resolution (i.e. pixel size).The effective doses for personnel screening systems are unlikely to be in compliance with the American National Standards Institute standard NS 43.17 unless the pixel sizes are >4 mm. Nevertheless, calculated effective doses are well below doses associated with health effects.

On Similarity Coefficients for 2x2 Tables and Correction for Chance

ERIC Educational Resources Information Center

Warrens, Matthijs J.

2008-01-01

This paper studies correction for chance in coefficients that are linear functions of the observed proportion of agreement. The paper unifies and extends various results on correction for chance in the literature. A specific class of coefficients is used to illustrate the results derived in this paper. Coefficients in this class, e.g. the simple…

Mu2e Technical Design Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bartoszek, L.; et al.

Fermi National Accelerator Laboratory and the Mu2e Collaboration, composed of about 155 scientists and engineers from 28 universities and laboratories around the world, have collaborated to create this technical design for a new facility to study charged lepton flavor violation using the existing Department of Energy investment in the Fermilab accelerator complex. Mu2e proposes to measure the ratio of the rate of the neutrinoless, coherent conversion of muons into electrons in the field of a nucleus, relative to the rate of ordinary muon capture on the nucleus. The conversion process is an example of charged lepton flavor violation (CLFV), amore » process that has never been observed experimentally. The significant motivation behind the search for muon-to-electron conversion is discussed in Chapter 3.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaufman, A.N.; Morehead, J.J.; Brizard, A.J.

Linear conversion of an incoming magnetosonic wave (a.k.a. fast or compressional wave) to an ion-hybrid wave can be considered as a 3-step process in ray phase space. This is demonstrated by casting the cold-fluid model into the Friedland-Kaufman normal form for linear mode conversion. First, the incoming magnetosonic ray (MSR) converts a fraction of its action to an {ital intermediate} ion-hybrid ray (IHR), with the transmitted ray proceeding through the conversion layer. The IHR propagates in k-space to a {ital second} conversion point, where it converts in turn a fraction of its action into a {ital reflected} MSR, with themore » remainder of the its action constituting the {ital converted} IHR. The modular approach gives {ital exact} agreement with the more standard Budden formulation for the transmission, reflection and conversion coefficients, but has the important advantage of exposing the intermediate IHR. The existence of the intermediate IHR has important physical consequences as it can resonate with {alpha} particles. We estimate the time-integrated damping coefficient between the two conversions and show that {integral}{gamma}dt is of order {minus}100, thus the IH wave is completely annihilated between conversions and transfers its energy to the {alpha}{close_quote}s. This suggests that proposals to use the IH mode for current drive or DT heating are likely to fail in the presence of fusion {alpha}{close_quote}s. {copyright} {ital 1997 American Institute of Physics.}« less

Measurements of the O+ plus N2 and O+ plus O2 reaction rates from 300 to 900 K

NASA Technical Reports Server (NTRS)

Chen, A.; Johnsen, R.; Biondi, M. A.

1977-01-01

Rate coefficients for the O(+) + N2 atom transfer and O(+) + O2 charge transfer reactions are determined at thermal energies between 300 K and 900 K difference in a heated drift tube mass spectrometer apparatus. At 300 K the values K(O(+) + N2) = (1.2 plus or minus 0.1) x 10 to the negative 12 power cubic cm/sec and k(O(+) + O2) = (2.1 plus or minus 0.2) x 10 to the negative 11 power cubic cm/sec were obtained, with a 50% difference decrease in the reaction rates upon heating to 700 K. These results are in good agreement with heated flowing afterglow results, but the O(+) + O2 thermal rate coefficients are systematically lower than equivalent Maxwellian rates inferred by conversion of nonthermal drift tube and flow drift data.

Thermophotovoltaic Energy Conversion for Personal Power Sources

DTIC Science & Technology

2012-02-01

FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-MM-YYYY) February 2012 2. REPORT TYPE Final 3. DATES COVERED (From - To) November 2010 to September...accepted power source to date . 3 2. Thermophotovoltaic Energy Conversion 2.1 Thermophotovoltaic Overview Figure 1 describes the primary...photovoltaic material systems for thermophotovoltaic conversion to date are gallium antimonide (GaSb)-related materials (homogeneous: 0.72 eV

Beach Street: Student's Book 2.

ERIC Educational Resources Information Center

Delaruelle, Susan

The student's textbook contains lessons in intermediate English based on a fictitious community in Australia and its inhabitants. Lessons focus on two types of interaction: those with an interpersonal motivation (e.g., casual conversations), and those with pragmatic motivation (e.g., buying and selling, seeking help). The casual conversations are…

Conversion of laser energy to gas kinetic energy

NASA Technical Reports Server (NTRS)

Caledonia, G. E.

1976-01-01

Techniques for the gas phase absorption of laser radiation for ultimate conversion to gas kinetic energy are discussed. Particular emphasis is placed on absorption by the vibration rotation bands of diatomic molecules at high pressures. This high pressure absorption appears to offer efficient conversion of laser energy to gas translational energy. Bleaching and chemical effects are minimized and the variation of the total absorption coefficient with temperature is minimal.

Decomposition of carbon dioxide by recombining hydrogen plasma with ultralow electron temperature

NASA Astrophysics Data System (ADS)

Yamazaki, Masahiro; Nishiyama, Shusuke; Sasaki, Koichi

2018-06-01

We examined the rate coefficient for the decomposition of CO2 in low-pressure recombining hydrogen plasmas with electron temperatures between 0.15 and 0.45 eV, where the electron-impact dissociation was negligible. By using this ultralow-temperature plasma, we clearly observed decomposition processes via vibrational excited states. The rate coefficient of the overall reaction, CO2 + e → products, was 1.5 × 10‑17 m3/s in the ultralow-temperature plasma, which was 10 times larger than the decomposition rate coefficient of 2 × 10‑18 m3/s in an ionizing plasma with an electron temperature of 4 eV.

Measurement of the electron-impact transfer rate coefficients between the Kr(1s) states in an afterglow discharge

NASA Astrophysics Data System (ADS)

Qiu, Jie; Cheng, Zhi-Wen; Zhu, Xi-Ming; Pu, Yi-Kang

2018-04-01

The rate coefficients for the electron-impact transfer from Kr(1s5) to Kr(1s4) and from Kr(1s3) to Kr(1s2) are measured in the electron temperature (T e) range between 0.07 eV and 1 eV. In the afterglow of a capacitive krypton discharge at a fixed pressure of 20 mTorr and a peak rf power ranging from 4 to 128 W, the densities of four krypton 1s states, the electron temperature and the electron density are measured by diode laser absorption, a Langmuir probe and a microwave interferometer, respectively. With these measured quantities, the rate coefficients are obtained from a population model for krypton metastable states. The measured rate coefficients are compared with those derived from the excitation cross sections of Kr metastable states calculated by different R-matrix models. It is found that our results agree best with that from Allan et al [1]. Moreover, we analyze the assumptions made in the population model and discuss their possible impact on the accuracy of the measured rate coefficients, especially for the low T e (0.1-0.2 eV) range and a higher T e (0.4-1 eV) range.

Determination of the external mass transfer coefficient and influence of mixing intensity in moving bed biofilm reactors for wastewater treatment.

PubMed

Nogueira, Bruno L; Pérez, Julio; van Loosdrecht, Mark C M; Secchi, Argimiro R; Dezotti, Márcia; Biscaia, Evaristo C

2015-09-01

In moving bed biofilm reactors (MBBR), the removal of pollutants from wastewater is due to the substrate consumption by bacteria attached on suspended carriers. As a biofilm process, the substrates are transported from the bulk phase to the biofilm passing through a mass transfer resistance layer. This study proposes a methodology to determine the external mass transfer coefficient and identify the influence of the mixing intensity on the conversion process in-situ in MBBR systems. The method allows the determination of the external mass transfer coefficient in the reactor, which is a major advantage when compared to the previous methods that require mimicking hydrodynamics of the reactor in a flow chamber or in a separate vessel. The proposed methodology was evaluated in an aerobic lab-scale system operating with COD removal and nitrification. The impact of the mixing intensity on the conversion rates for ammonium and COD was tested individually. When comparing the effect of mixing intensity on the removal rates of COD and ammonium, a higher apparent external mass transfer resistance was found for ammonium. For the used aeration intensities, the external mass transfer coefficient for ammonium oxidation was ranging from 0.68 to 13.50 m d(-1) and for COD removal 2.9 to 22.4 m d(-1). The lower coefficient range for ammonium oxidation is likely related to the location of nitrifiers deeper in the biofilm. The measurement of external mass transfer rates in MBBR will help in better design and evaluation of MBBR system-based technologies. Copyright © 2015 Elsevier Ltd. All rights reserved.

Ultrafast internal conversion dynamics of highly excited pyrrole studied with VUV/UV pump probe spectroscopy.

PubMed

Horton, Spencer L; Liu, Yusong; Chakraborty, Pratip; Matsika, Spiridoula; Weinacht, Thomas

2017-02-14

We study the relaxation dynamics of pyrrole after excitation with an 8 eV pump pulse to a state just 0.2 eV below the ionization potential using vacuum ultraviolet/ultraviolet pump probe spectroscopy. Our measurements in conjunction with electronic structure calculations indicate that pyrrole undergoes rapid internal conversion to the ground state in less than 300 fs. We find that internal conversion to the ground state dominates over dissociation.

Low noise scintillation detectors with a P-47 thin layer screen for electrons of several keV

NASA Astrophysics Data System (ADS)

Kajcsos, Zs.; Meisel, W.; Griesbach, P.; Gütlich, P.; Sauer, Ch.; Kurz, R.; Hildebrand, K.; Albrecht, R.; Ligtenberg, M. A. C.

1994-09-01

The applicability of a low-noise scintillation detector (ScD) for the registration of electrons of several keV energy has been studied employing photomultipliers (PM) of different types and sizes. With the application of a sedimented P-47 scintillation screen, the values of the low-energy sensitivity limit and those of the light conversion coefficient were determined as about 2.7-4.7 keV and 2.8-6.6 photoelectrons/keV, respectively, for the set of PM's (Philips-Valvo XP 2020, Philips-Valvo XP 2052, Philips-Valvo XP 2972, EMI 9124a) studied. It is concluded that such scintillation detectors might be used advantageously as electron counters in the range of E > 5 keV. Applications below this kinetic energy value are also feasible when applying a floating acceleration of several kV to the ScD — a voltage much lower than the values required for Everhart-Thornley detectors.

Fabrication of Natural Sensitizer Extracted from Mixture of Purple Cabbage, Roselle, Wormwood and Seaweed with High Conversion Efficiency for DSSC.

PubMed

Chang, Ho; Lai, Xuan-Rong

2016-02-01

This study aims to deal with the influence of different solvent in extraction of natural sensitizer and different thickness of photoelectrode thin film on the photoelectric conversion efficiency and the electron transport properties for the prepared dye-sensitized solar cells (DSSC). The natural dyes of anthocyanin and chlorophyll dyes are extracted from mixture of purple cabbage and roselle and mixture of wormwood and seaweed, respectively. The experimental results show the cocktail dye extracted with ethanol and rotating speed of spin coating at 1000 rpm can achieve the greatest photoelectric conversion efficiency up to 1.85%. Electrochemical impedance result shows that the effective diffusion coefficient for the prepared DSSC with the thickness of photoelectrode thin film at 21 microm are 5.23 x 10(-4) cm2/s.

Standardization and determination of the total internal conversion coefficient of In-111.

PubMed

Matos, Izabela T; Koskinas, Marina F; Nascimento, Tatiane S; Yamazaki, Ione M; Dias, Mauro S

2014-05-01

The standardization of (111)In by means of a 4πβ-γ coincidence system, composed of a proportional counter in 4π geometry, coupled to a 20% relative efficiency HPGe crystal, for measuring gamma-rays is presented. The data acquisition was performed by means of the software coincidence system (SCS) and the activity was determined by the extrapolation technique. Two gamma-ray windows were selected: at 171 keV and 245 keV total absorption peaks, allowing the determination of the total internal conversion coefficient for these two gamma transitions. The results were compared with those available in the literature. © 2013 Published by Elsevier Ltd.

Voxel2MCNP: a framework for modeling, simulation and evaluation of radiation transport scenarios for Monte Carlo codes.

PubMed

Pölz, Stefan; Laubersheimer, Sven; Eberhardt, Jakob S; Harrendorf, Marco A; Keck, Thomas; Benzler, Andreas; Breustedt, Bastian

2013-08-21

The basic idea of Voxel2MCNP is to provide a framework supporting users in modeling radiation transport scenarios using voxel phantoms and other geometric models, generating corresponding input for the Monte Carlo code MCNPX, and evaluating simulation output. Applications at Karlsruhe Institute of Technology are primarily whole and partial body counter calibration and calculation of dose conversion coefficients. A new generic data model describing data related to radiation transport, including phantom and detector geometries and their properties, sources, tallies and materials, has been developed. It is modular and generally independent of the targeted Monte Carlo code. The data model has been implemented as an XML-based file format to facilitate data exchange, and integrated with Voxel2MCNP to provide a common interface for modeling, visualization, and evaluation of data. Also, extensions to allow compatibility with several file formats, such as ENSDF for nuclear structure properties and radioactive decay data, SimpleGeo for solid geometry modeling, ImageJ for voxel lattices, and MCNPX's MCTAL for simulation results have been added. The framework is presented and discussed in this paper and example workflows for body counter calibration and calculation of dose conversion coefficients is given to illustrate its application.

Anti-prelog reduction of prochiral carbonyl compounds by Oenococcus oeni in a biphasic system.

PubMed

Hu, Jian; Xu, Yan

2006-07-01

An aqueous-organic biphasic system was established and used with whole cells of Oenococcus oeni to reduce 2-octanone to (R)-2-octanol. The conversion reached 99% when the Tris/borate buffer was increased from 50 mM to 300 mM in the aqueous phase. In addition, the conversion increased as the log P value of the organic solvent changed from 0.5 to 6.6. Under optimized conditions, the conversion of (R)-2-octanol reached 99% from 0.5 M 2-octanone with an optical purity of 99% e.e. The biphasic system allows the anti-Prelog reduction of aliphatic and aromatic ketones to furnish (R)-configurated alcohols in high optical purity as well.

SU-F-T-669: Commissioning of An Electronic Brachytherapy System for Targeted Mouse Irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Culberson, W; Micka, J; Carchman, E

Purpose: The aim of this study was to commission the Xoft Axxent™ electronic brachytherapy (eBT) source and 10 mm diameter surface applicator with NIST traceability for targeted irradiations of mouse anal carcinomas. Methods: The Xoft Axxent™ electronic brachytherapy (eBT) and 10 mm diameter surface applicator was chosen by the collaborating physician as a radiation delivery mechanism for mouse anal carcinomas. The target dose was 2 Gy at a depth of 3 mm in tissue to be delivered in a single fraction. To implement an accurate and reliable irradiation plan, the system was commissioned by first determining the eBT source outputmore » and corresponding dose rate at a depth of 3 mm in tissue. This was determined through parallel-plate ion chamber measurements and published conversion factors. Well-type ionization chamber measurements were used to determine a transfer coefficient, which correlates the measured dose rate at 3 mm to the NIST-traceable quantity, air-kerma rate at 50 cm in air, for eBT sources. By correlating these two quantities, daily monitoring in the well chamber becomes an accurate and efficient quality assurance technique. Once the dose-rate was determined, a treatment recipe was developed and confirmed with chamber measurements to deliver the requested dose. Radiochromic film was used to verify the dose distribution across the field. Results: Dose rates at 3 mm depth in tissue were determined for two different Xoft Axxent™ sources and correlated with NIST-traceable well-type ionization chamber measurements. Unique transfer coefficients were determined for each source and the treatment recipe was validated by measurements. Film profiles showed a uniform dose distribution across the field. Conclusion: A Xoft Axxent™ eBT system was successfully commissioned for use in the irradiation of mouse rectal tumors. Dose rates in tissue were determined as well as other pertinent parameters to ensure accurate delivery of dose to the target region.« less

Passive, Low Cost Neutron Detectors for Neutron Diagnostics at the National Ignition Facility

DTIC Science & Technology

2013-03-01

Facility PTFE Polytetrafluoroethylene TLD Thermoluminescent Dosimeter α Conversion Coefficient (Conversion...because they required a large investment in automated track counting equipment. Thermoluminescent dosimeters ( TLDs ) remained as a viable option. They...necessary to predict radiation damage to measurement electronics . Due to programmatic and facility limitations, traditional neutron measurement

Pyroelectricity of silicon-doped hafnium oxide thin films

NASA Astrophysics Data System (ADS)

Jachalke, Sven; Schenk, Tony; Park, Min Hyuk; Schroeder, Uwe; Mikolajick, Thomas; Stöcker, Hartmut; Mehner, Erik; Meyer, Dirk C.

2018-04-01

Ferroelectricity in hafnium oxide thin films is known to be induced by various doping elements and in solid-solution with zirconia. While a wealth of studies is focused on their basic ferroelectric properties and memory applications, thorough studies of the related pyroelectric properties and their application potential are only rarely found. This work investigates the impact of Si doping on the phase composition and ferro- as well as pyroelectric properties of thin film capacitors. Dynamic hysteresis measurements and the field-free Sharp-Garn method were used to correlate the reported orthorhombic phase fractions with the remanent polarization and pyroelectric coefficient. Maximum values of 8.21 µC cm-2 and -46.2 µC K-1 m-2 for remanent polarization and pyroelectric coefficient were found for a Si content of 2.0 at%, respectively. Moreover, temperature-dependent measurements reveal nearly constant values for the pyroelectric coefficient and remanent polarization over the temperature range of 0 ° C to 170 ° C , which make the material a promising candidate for IR sensor and energy conversion applications beyond the commonly discussed use in memory applications.

A simple formulation for deriving effective atomic numbers via electron density calibration from dual-energy CT data in the human body.

PubMed

Saito, Masatoshi; Sagara, Shota

2017-06-01

The main objective of this study is to propose a simple formulation (which we called DEEDZ) for deriving effective atomic numbers (Z eff ) via electron density (ρ e ) calibration from dual-energy (DE) CT data. We carried out numerical analysis of this DEEDZ method for a large variety of materials with known elemental compositions and mass densities using an available photon cross sections database. The new conversion approach was also applied to previously published experimental DECT data to validate its practical feasibility. We performed numerical analysis of the DEEDZ conversion method for tissue surrogates that have the same chemical compositions and mass densities as a commercial tissue-characterization phantom in order to determine the parameters necessary for the ρ e and Z eff calibrations in the DEEDZ conversion. These parameters were then applied to the human-body-equivalent tissues of ICRU Report 46 as objects of interest with unknown ρ e and Z eff . The attenuation coefficients of these materials were calculated using the XCOM photon cross sections database. We also applied the DEEDZ conversion to experimental DECT data available in the literature, which was measured for two commercial phantoms of different shapes and sizes using a dual-source CT scanner at 80 kV and 140 kV/Sn. The simulated Z eff 's were in excellent agreement with the reference values for almost all of the ICRU-46 human tissues over the Z eff range from 5.83 (gallstones-cholesterol) to 16.11 (bone mineral-hydroxyapatite). The relative deviations from the reference Z eff were within ± 0.3% for all materials, except for one outlier that presented a -3.1% deviation, namely, the thyroid. The reason for this discrepancy is that the thyroid contains a small amount of iodine, an element with a large atomic number (Z = 53). In the experimental case, we confirmed that the simple formulation with less fit parameters enable to calibrate Z eff as accurately as the existing calibration procedure. The DEEDZ conversion method based on the simple formulation proposed could facilitate the construction of ρ e and Z eff images from acquired DECT data. © 2017 American Association of Physicists in Medicine.

Experimental study of Pulsed Laser Deposited Cu2ZnSnS 4 (CZTS) thin films for photovoltaic applications

NASA Astrophysics Data System (ADS)

Nandur, Abhishek S.

Thin film solar cells are gaining momentum as a renewable energy source. Reduced material requirements (< 2 mum in total film thickness) coupled with fast, low-cost production processes make them an ideal alternative to Si (>15 mum in total thickness) solar cells. Among the various thin film solar absorbers that have been proposed, CZTS (Cu2ZnSnS4) has become the subject of intense interest because of its optimal band gap (1.45 eV), high absorption coefficient (104 cm--1 ) and abundant elemental components. Pulsed Laser Deposition (PLD) provides excellent control over film composition since films are deposited under high vacuum with excellent stoichiometry transfer from the target. Defect-free, near-stoichiometric poly-crystalline CZTS thin films were deposited using PLD from a stoichiometrically close CZTS target (Cu2.6Zn1.1Sn0.7S3.44). The effects of fabrication parameters such as laser energy density, deposition time, substrate temperature and sulfurization (annealing in sulfur) on the surface morphology, composition and optical absorption of the CZTS thin films were examined. The results show that the presence of secondary phases, present both in the bulk and on the surface, affected the electrical and optical properties of the CZTS thin films and the CZTS based TFSCs. After selectively etching away the secondary phases with DIW, HCl and KCN, it was observed that their removal improved the performance of CZTS based TFSCs. Optimal CZTS thin films exhibited an optical band gap of 1.54 eV with an absorption coefficient of 4x10 4cm-1 with a low volume of secondary phases. A TFSC fabricated with the best CZTS thin film obtained from the experimental study done in this thesis showed a conversion efficiency of 6.41% with Voc = 530 mV, Jsc= 27.5 mA/cm2 and a fill factor of 0.44.

Ab-Initio-Based Kinetic Modeling to Understand RAFT Exchange: The Case of 2-Cyano-2-Propyl Dodecyl Trithiocarbonate and Styrene.

PubMed

Desmet, Gilles B; De Rybel, Nils; Van Steenberge, Paul H M; D'hooge, Dagmar R; Reyniers, Marie-Françoise; Marin, Guy B

2018-01-01

Ab-initio-calculated rate coefficients for addition and fragmentation in reversible-addition fragmentation chain transfer (RAFT) polymerization of styrene with 2-cyano-2-propyl dodecyl trithiocarbonate initiated by azobisisobutyronitrile allow the reliable simulation of the experimentally observed conversion, number average chain length, and dispersity. The rate coefficient for addition of a macroradical R i to the macroRAFT agent R i X at 333 K (6.8 10 4 L mol -1 s -1 ) is significantly lower than to the initial RAFT agent R 0 X (3.2 10 6 L mol -1 s -1 ), mainly due to a difference in activation energy (15.4 vs 3.0 kJ mol -1 ), which causes the dispersity to spike in the beginning of the polymerization. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Abiotic Transformation Of Estrogens In Synthetic Municipal Wastewater: An Alternative For Treatment?

EPA Science Inventory

The abiotic transformation of estrogens, including estrone (E1), estradiol (E2), estriol (E3) and ethinylestradiol (EE2), in the presence of model vegetable matter was confirmed in this study. Batch experiments were performed to model the catalytic conversion of E1, E2, E3, and ...

Thermal electron attachment to chlorinated alkenes in the gas phase

NASA Astrophysics Data System (ADS)

Wnorowski, K.; Wnorowska, J.; Michalczuk, B.; Jówko, A.; Barszczewska, W.

2017-01-01

This paper reports the measurements of the rate coefficients and the activation energies of the electron capture processes with various chlorinated alkenes. The electron attachment processes in the mixtures of chlorinated alkenes with carbon dioxide have been investigated using a Pulsed Townsend technique. This study has been performed in the temperature range (298-378) K. The obtained rate coefficients more or less depended on temperature in accordance to Arrhenius equation. The activation energies (Ea's) were determined from the fit to the experimental data points with function ln(k) = ln(A) - Ea/kBT. The rate coefficients at 298 K were equal to 1.0 × 10-10 cm3 s-1, 2.2 × 10-11 cm3 s-1, 1.6 × 10-9 cm3 s-1, 4.4 × 10-8 cm3 s-1, 2.9 × 10-12 cm3 s-1 and 7.3 × 10-12 cm3 s-1 and activation energies were: 0.27 eV, 0.26 eV, 0.25 eV, 0.21 eV, 0.55 eV and 0.42 eV, for trans-1,2-dichloroethylene, cis-1,2-dichloroethylene, trichloroethylene, tetrachloroethylene, 2-chloropropene, 3-chloropropene respectively.

Conversion-electron spectroscopy and gamma-gamma angular correlation measurements in 116Sn

NASA Astrophysics Data System (ADS)

Cross, D. S.; Pore, J. L.; Andreoiu, C.; Ball, G. C.; Bender, P. C.; Chester, A. S.; Churchman, R.; Demand, G. A.; Diaz Varela, A.; Dunlop, R.; Garnsworthy, A. B.; Garrett, P. E.; Hackman, G.; Hadinia, B.; Jigmeddorj, B.; Laffoley, A. T.; Liblong, A.; Kanungo, R.; Miller, D. T.; Noakes, B.; Petrache, C. M.; Starosta, K.; Svensson, C. E.; Voss, P.; Wang, Z.-M.; Wilson, J. M.; Wood, J. L.; Yates, S. W.

2017-11-01

The 116Sn nucleus was studied via the β- decay of 116In utilizing the 8π spectrometer and its auxiliary detectors at TRIUMF-ISAC. The resulting K-shell conversion coefficients, K/L ratios, and multipole mixing ratios are presented. The 23+ → 21+ 931 keV and 22+ → 21+ 819 keV transition mixing ratios were re-measured and found to be δ = +1.8_{-0.5}^{+0.7} and -1.83(8), respectively. Newly measured mixing ratios for transitions among the low-lying I^{π} = 4+ states in 116Sn, when combined with γ-ray intensity data, suggest that the 2529 keV 42+ state possesses a neutron broken-pair admixture in addition to its dominant proton 2p-2h component.

Growth and optical properties of Pr,Yb-codoped KY 3F 10 fluoride single crystals for up-conversion visible luminescence

NASA Astrophysics Data System (ADS)

Kim, Kyoung Jin; Jouini, Anis; Yoshikawa, Akira; Simura, Rayko; Boulon, Georges; Fukuda, Tsuguo

2007-02-01

We investigate different ways to realize laser emission from (Pr 3+) 3P J=0,1,2 levels by pump sources other than the common argon and excimer-dye laser. The use of infrared (IR) laser diodes in combination with intra- and inter-ionic energy transfer processes (up-conversion) could be an efficient solution towards laser oscillation. Pr 3+,Yb 3+-codoped KY 3F 10 (Pr, Yb:KYF) single crystals were successfully grown by the micro-pulling-down (μ-PD) method. The crystals were transparent with a slightly greenish color, 2.0-2.5 mm in diameter, 20-30 mm in length and free from visible inclusions and cracks. Effective segregation coefficients of Pr and Yb in KYF were studied by means of absorption and chemical analysis. Strong visible emission via selective IR pumping with λ=975 nm and up-conversion excitation were obtained in Pr, Yb:KYF at room temperature (RT). Luminescence measurements have been carried out and the decay kinetics of the Pr 3+ visible emissions was investigated by room temperature time-resolved spectra.

MEASURING REDDENING WITH SLOAN DIGITAL SKY SURVEY STELLAR SPECTRA AND RECALIBRATING SFD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schlafly, Edward F.; Finkbeiner, Douglas P.

2011-08-20

We present measurements of dust reddening using the colors of stars with spectra in the Sloan Digital Sky Survey. We measure reddening as the difference between the measured and predicted colors of a star, as derived from stellar parameters from the Sloan Extension for Galactic Understanding and Exploration Stellar Parameter Pipeline. We achieve uncertainties of 56, 34, 25, and 29 mmag in the colors u - g, g - r, r - i, and i - z, per star, though the uncertainty varies depending on the stellar type and the magnitude of the star. The spectrum-based reddening measurements confirm ourmore » earlier 'blue tip' reddening measurements, finding reddening coefficients different by -3%, 1%, 1%, and 2% in u - g, g - r, r - i, and i - z from those found by the blue tip method, after removing a 4% normalization difference. These results prefer an R{sub V} = 3.1 Fitzpatrick reddening law to O'Donnell or Cardelli et al. reddening laws. We provide a table of conversion coefficients from the Schlegel et al. (SFD) maps of E(B - V) to extinction in 88 bandpasses for four values of R{sub V} , using this reddening law and the 14% recalibration of SFD first reported by Schlafly et al. and confirmed in this work.« less

The endocrine disrupting alkylphenols and 4,4'-DDT interfere with estrogen conversion and clearance by mouse liver cytosol.

PubMed

El-Hefnawy, Talal; Hernandez, Claudia; Stabile, Laura P

2017-09-01

Endocrine disrupting chemicals (EDCs) are ubiquitous compounds known for negative impacts on reproductive functions and for increasing cancer risk. EDCs are believed to cause the harmful effects in part through their inappropriate low-affinity binding to steroid receptors and other possible non-receptor mediated paradigms, however there is a need to further elucidate other mechanisms involving the direct and indirect impact of EDCs on reproductive functions. We examined the metabolism of 17β-estradiol (E2) and estrone (E1) by cell-free hepatic cytosol in the presence of alkylphenols (nonylphenol/NP and 4-tert-octylphenol/tOP), Dichlorodiphenyltrichloroethane (4,4'-DDT) and other EDCs. Tandem liquid chromatography mass spectrometry was utilized to quantitatively assess the impact of each EDC on estrogen clearance, inter-conversions and downstream metabolism by mouse liver cytosol. The results revealed that NP and tOP (0.1-3μg/mL) significantly reduced the hepatic cytosol clearance and biotransformation of estrogens with inclination for accumulating E2, the stronger estrogen form, than E1. Alkylphenols also caused up to a 34-fold increase in the E2/E1 ratio possibly by suppressing the hepatic E2→E1 conversion by 17β-hydroxysteroid dehydrogenase (17βHSD) types 2, 4 while displaying a weaker inhibition of E1→E2 conversion by type 1, 17βHSD. On the other hand, the pesticide 4,4'-DDT was a weaker inhibitor of clearance of estrogens by the cytosol preparations when compared to alkylphenols, whereas chemicals such as phthalates and atrazine were ineffective. Our data suggest that exposure to NP, tOP and DDT can indirectly increase the estrogenic load by suppressing the hepatic clearance of estrogens and by elevating the E2/1 ratio and could therefore increase the risk of reproductive lesions. Copyright © 2017 Society for Biology of Reproduction & the Institute of Animal Reproduction and Food Research of Polish Academy of Sciences in Olsztyn. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.

Crystal growth of organics for nonlinear optical applications

NASA Technical Reports Server (NTRS)

Singh, N. B.; Mazelsky, R.

1993-01-01

The crystal growth and characterization of organic and inorganic nonlinear optical materials were extensively studied. For example, inorganic crystals such as thallium arsenic selenide were studied in our laboratory for several years and crystals in sizes over 2.5 cm in diameter are available. Organic crystals are suitable for the ultraviolet and near infrared region, but are relatively less developed than their inorganic counterparts. Very high values of the second harmonic conversion efficiency and the electro-optic coefficient were reported for organic compounds. Single crystals of a binary organic alloy based on m.NA and CNA were grown and higher second harmonic conversion efficiency than the values reported for m.NA were observed.

A theory of the inverse magnetoelectric effect in layered magnetostrictive-piezoelectric structures

NASA Astrophysics Data System (ADS)

Filippov, D. A.; Radchenko, G. S.; Firsova, T. O.; Galkina, T. A.

2017-05-01

A theory of the inverse magnetoelectric effect in layered structures has been presented. The theory is based on solving the equations of elastodynamics and electrostatics separately for the magnetostrictive and piezoelectric phases, taking into account the conditions at the interface between the phases. Expressions for the coefficient of inverse magnetoelectric conversion through the parameters characterizing the magnetostrictive and piezoelectric phases have been obtained. Theoretical dependences of the inverse magnetoelectric conversion coefficient on the frequency of the alternating-current electric field for the three-layer PZT-Ni-PZT structure and the two-layer terfenol- D-PZT structure have been calculated. The results of the calculations are in good agreement with the experimental data.

Reflection and transmission coefficients for guided waves reflected by defects in viscoelastic material plates.

PubMed

Hosten, Bernard; Moreau, Ludovic; Castaings, Michel

2007-06-01

The paper presents a Fourier transform-based signal processing procedure for quantifying the reflection and transmission coefficients and mode conversion of guided waves diffracted by defects in plates made of viscoelastic materials. The case of the S(0) Lamb wave mode incident on a notch in a Perspex plate is considered. The procedure is applied to numerical data produced by a finite element code that simulates the propagation of attenuated guided modes and their diffraction by the notch, including mode conversion. Its validity and precision are checked by the way of the energy balance computation and by comparison with results obtained using an orthogonality relation-based processing method.

Chromatic effect in a novel THz generation scheme

NASA Astrophysics Data System (ADS)

Li, Bin; Zhang, Wenyan; Liu, Xiaoqing; Deng, Haixiao; Lan, Taihe; Liu, Bo; Liu, Jia; Wang, Xingtao; Zeng, Zhinan; Zhang, Lijian

2017-11-01

Deriving single or few cycle terahertz (THz) pulse by an intense femtosecond laser through cascaded optical rectification is a crucial technique in cutting-edge time-resolved spectroscopy to characterize micro-scale structures and ultrafast dynamics. Due to the broadband nature of the ultrafast driving laser, the chromatic effect limits the THz conversion efficiency in optical rectification crystals, especially for those implementing the pulse-front tilt scheme, e.g. lithium niobate (LN) crystal, has been prevalently used in the past decade. In this research we developed a brand new type of LN crystal utilizing Brewster coupling, and conducted systematically experimental and simulative investigation for the chromatic effect and multi-dimensionally entangled parameters in THz generation, predicting that an extreme conversion efficiency of ˜10% would be potentially achievable at the THz absorption coefficient of ˜0.5 cm-1. Moreover, we first discovered that the chirp of the driving laser plays a decisive role in the pulse-front tilt scheme, and the THz generation efficiency could be enhanced tremendously by applying an appropriate chirp.

49 CFR 171.10 - Units of measure.

Code of Federal Regulations, 2011 CFR

2011-10-01

... measure in this subchapter are expressed using the International System of Units (“SI” or metric). Where... abbreviated. (c) Conversion values. (1) Conversion values are provided in the following table and are based on values provided in ASTM E 380, “Standard for Metric Practice”. (2) If an exact conversion is needed, the...

49 CFR 171.10 - Units of measure.

Code of Federal Regulations, 2012 CFR

2012-10-01

... measure in this subchapter are expressed using the International System of Units (“SI” or metric). Where... abbreviated. (c) Conversion values. (1) Conversion values are provided in the following table and are based on values provided in ASTM E 380, “Standard for Metric Practice”. (2) If an exact conversion is needed, the...

49 CFR 171.10 - Units of measure.

Code of Federal Regulations, 2014 CFR

2014-10-01

... measure in this subchapter are expressed using the International System of Units (“SI” or metric). Where... abbreviated. (c) Conversion values. (1) Conversion values are provided in the following table and are based on values provided in ASTM E 380, “Standard for Metric Practice”. (2) If an exact conversion is needed, the...

49 CFR 171.10 - Units of measure.

Code of Federal Regulations, 2010 CFR

2010-10-01

... measure in this subchapter are expressed using the International System of Units (“SI” or metric). Where... abbreviated. (c) Conversion values. (1) Conversion values are provided in the following table and are based on values provided in ASTM E 380, “Standard for Metric Practice”. (2) If an exact conversion is needed, the...

49 CFR 171.10 - Units of measure.

Code of Federal Regulations, 2013 CFR

2013-10-01

... measure in this subchapter are expressed using the International System of Units (“SI” or metric). Where... abbreviated. (c) Conversion values. (1) Conversion values are provided in the following table and are based on values provided in ASTM E 380, “Standard for Metric Practice”. (2) If an exact conversion is needed, the...

New Crystalline Materials for Nonlinear Frequency Conversion, Electro-Optic Modulation, and Mid-Infrared Gain Media

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adams, J

New crystalline materials were investigated for applications in frequency conversion of near-infrared wavelengths and as gain media for tunable mid-infrared solid-state lasers. GaCa{sub 4}O(BO{sub 3}){sub 3} (GdCOB), YCa{sub 4}O(BO{sub 3}){sub 3} (YCOB), LaCa{sub 4}O(BO{sub 3}){sub 3} (LaCOB), and Gd{sub 0.275}Y{sub 0.725}Ca{sub 4}O(BO{sub 3}){sub 3} were characterized for frequency conversion of 1 {micro}m lasers. For type I doubling at 1064 nm, LaCOB, GdCOB, and YCOB were found to have effective coupling coefficients (d{sub eff}) of 0.52 {+-} 0.05, 0.78 {+-} 0.06, and 1.12 {+-} 0.07 pm/V, respectively. LaCOB was measured to have angular and thermal sensitivities of 1224 {+-} 184 (cm-rad){supmore » -1} and < 0.10 (cm-{sup o}C){sup -1}, respectively. The effective coupling coefficient for type II noncritically phasematched (NCPM) doubling at 1064 nm in Gd{sub 0.275}Y{sub 0.725}Ca{sub 4}O(BO{sub 3}){sub 3} was measured to be 0.37 {+-} 0.04 pm/V. We predict LaCOB to have a type I NCPM fundamental wavelength of 1042 {+-} 1.5 nm. Due to its low angular and thermal sensitivities for doubling near 1047 nm, LaCOB has potential for frequency doubling of high-average power Nd:LiYF{sub 4} and Yb:Sr{sub 5}(P0{sub 4}){sub 3}F lasers. LaCOB, GdCOB, and YCOB were also investigated for optical parametric oscillator applications and we determined that they may have potential in a Ti:sapphire pumped oscillator. The effective linear electro-optic coefficients (r{sub eff}) were measured along dielectric directions in YCOB and a maximum r{sub eff} of 10.8 pm/V was found. For a crystal with a 5:1 aspect ratio, the corresponding half-wave voltage at 1064 nm would be 19.6 kV. Therefore a Pockels cell composed of two YCOB crystals with 5:1 aspect ratios would have a required half-wave voltage <10 kV. Moderate coupling coefficients (3 x KH{sub 2}PO{sub 4}), low thermal sensitivities, ease of growth to large sizes, non-hygroscopicity, and favorable polishing and coating characteristics make LaCOB, GdCOB, and YCOB attractive for frequency conversion of high-average power near-infrared lasers. Absorption and emission cross-sections of {approx}10{sup -18} cm{sup 2} were measured for Fe{sup 2+}:ZnSe in the 4 {micro}m region at temperatures below 220 K. Luminescence lifetimes were found that ranged from 5-110 {micro}s below 220 K. Tunable lasing action was demonstrated for the first time in Fe{sup 2+}:ZnSe with a tuning range from 3.98 {micro}m (20 K) to 4.54 {micro}m (180 K). The Fe{sup 2+}:ZnSe laser had thresholds {le}50 {micro}J and slope efficiencies {le}10% with 0.6% output coupling.« less

Calculation and characteristic analysis on synergistic effect of CF3I gas mixtures

NASA Astrophysics Data System (ADS)

Su, ZHAO; Yunkun, DENG; Yuhao, GAO; Dengming, XIAO

2018-06-01

CF3I is a potential SF6 alternative gas. In order to study the insulation properties and synergistic effects of CF3I/N2 and CF3I/CO2 gas mixtures, two-term approximate Boltzmann equations were used to obtain the ionization coefficient α, attachment coefficient η and the critical equivalent electrical field strength (E/N)cr. The results show that the (E/N)cr of CF3I gas at 300 K is 1.2 times that of SF6 gas, and CF3I/N2 and CF3I/CO2 gas mixtures both have synergistic effect occurred. The synergistic effect coefficient of CF3I/CO2 gas mixture was higher than that of CF3I/N2 gas mixture. But the (E/N)cr of CF3I/N2 is higher than that of CF3I/CO2 under the same conditions. When the content of CF3I exceeds 20%, the (E/N)cr of CF3I/N2 and CF3I/CO2 gas mixture increase linearly with the increasing of CF3I gas content. The breakdown voltage of CF3I/N2 gas mixture is also higher than that of CF3I/CO2 gas mixture in slightly non-uniform electrical field under power frequency voltage, but the synergistic effect coefficients of the two gas mixtures are basically the same.

Cyclic estrogenic fluctuation influences synaptic transmission of the medial vestibular nuclei in female rats.

PubMed

Pettorossi, Vito E; Frondaroli, Adele; Grassi, Silvarosa

2011-04-01

The estrous cycle in female rats influences the basal synaptic responsiveness and plasticity of the medial vestibular nucleus (MVN) neurons through different levels of circulating 17β-estradiol (cE(2)). The aim of this study was to verify, in the female rat, whether cyclic fluctuations of cE(2) influence long-term synaptic effects induced by high frequency afferent stimulation (HFS) in the MVN, since we found that HFS in the male rat induces fast long-term potentiation (fLTP), which depends on the neural synthesis of E(2) (nE(2)) from testosterone (T). We analyzed the field potential (FP) evoked in the MVN by vestibular afferent stimulation, under basal conditions, and after HFS, in brainstem slices of female rats during high levels (proestrus, PE) and low levels (diestrus, DE) of cE(2). Selective blocking agents of converting T enzymes were used. Unlike in the male rat, HFS induced three effects: fLTP through T conversion into E(2), and slow LTP (sLTP) and long-term depression (LTD), through T conversion into DHT. The occurrence of these effects depended on the estrous cycle phase: the frequency of fLTP was higher in DE, and those of sLTP and LTD were higher in PE. Conversely, the basal FP was also higher in PE than in DE.

Relativistic quasiparticle band structures of Mg2Si, Mg2Ge, and Mg2Sn: Consistent parameterization and prediction of Seebeck coefficients

NASA Astrophysics Data System (ADS)

Shi, Guangsha; Kioupakis, Emmanouil

2018-02-01

We apply density functional and many-body perturbation theory calculations to consistently determine and parameterize the relativistic quasiparticle band structures of Mg2Si, Mg2Ge, and Mg2Sn, and predict the Seebeck coefficient as a function of doping and temperature. The quasiparticle band gaps, including spin-orbit coupling effects, are determined to be 0.728 eV, 0.555 eV, and 0.142 eV for Mg2Si, Mg2Ge, and Mg2Sn, respectively. The inclusion of the semicore electrons of Mg, Ge, and Sn in the valence is found to be important for the accurate determination of the band gaps of Mg2Ge and Mg2Sn. We also developed a Luttinger-Kohn Hamiltonian and determined a set of band parameters to model the near-edge relativistic quasiparticle band structure consistently for all three compounds that can be applied for thermoelectric device simulations. Our calculated values for the Seebeck coefficient of all three compounds are in good agreement with the available experimental data for a broad range of temperatures and carrier concentrations. Our results indicate that quasiparticle corrections are necessary for the accurate determination of Seebeck coefficients at high temperatures at which bipolar transport becomes important.

TaiWan Ionospheric Model (TWIM) prediction based on time series autoregressive analysis

NASA Astrophysics Data System (ADS)

Tsai, L. C.; Macalalad, Ernest P.; Liu, C. H.

2014-10-01

As described in a previous paper, a three-dimensional ionospheric electron density (Ne) model has been constructed from vertical Ne profiles retrieved from the FormoSat3/Constellation Observing System for Meteorology, Ionosphere, and Climate GPS radio occultation measurements and worldwide ionosonde foF2 and foE data and named the TaiWan Ionospheric Model (TWIM). The TWIM exhibits vertically fitted α-Chapman-type layers with distinct F2, F1, E, and D layers, and surface spherical harmonic approaches for the fitted layer parameters including peak density, peak density height, and scale height. To improve the TWIM into a real-time model, we have developed a time series autoregressive model to forecast short-term TWIM coefficients. The time series of TWIM coefficients are considered as realizations of stationary stochastic processes within a processing window of 30 days. These autocorrelation coefficients are used to derive the autoregressive parameters and then forecast the TWIM coefficients, based on the least squares method and Lagrange multiplier technique. The forecast root-mean-square relative TWIM coefficient errors are generally <30% for 1 day predictions. The forecast TWIM values of foE and foF2 values are also compared and evaluated using worldwide ionosonde data.

Cultivation of E. coli in single- and ten-stage tower-loop reactors.

PubMed

Adler, I; Schügerl, K

1983-02-01

E. Coli was cultivated in batch and continuous operations in the presence of an antifoam agent in stirred-tank and in single- and ten-stage airlift tower reactors with an outer loop. The maximum specific growth rate, mu(m), the substrate yield coefficient, Y(x/s), the respiratory quotient, RQ, substrate conversion, U(s), the volumetric mass transfer coefficient, K(L)a, the specific interfacial area, a, and the specific power input, P/V(L), were measured and compared. If a medium is used with a concentration of complex substrates (extracts) 2.5 times higher than that of glucose, a spectrum of C sources is available and cell regulation influences reactor performance. Both mu(m) and Y(X/S), which were evaluated in batch reactors, cannot be used for continuous reactors or, when measured in stirred-tank reactors, cannot be employed for tower-loop reactors: mu(m) is higher in the stirred-tank batch than in the tower-loop batch reactor, mu(m) and Y(x/s) are higher in the continuous reactor than in the batch single-stage tower-loop reactor. The performance of the single-stage is better than that of the ten-stage reactor due to the inefficient trays employed. A reduction of the medium recirculation rate reduces OTR, U(s), Pr, and Y(X/S) and causes cell sedimentation and flocculation. The volumetric mass transfer coefficient is reduced with increasing cultivation time; the Sauter bubble diameter, d(s), remains constant and does not depend on operational conditions. An increase in the medium recirculation rate reduces k(L)a. The specific power input, P/V(L), for the single-stage tower loop is much lower with the same k(L)a value than for a stirred tank. The relationship k(L)a vs. P/V(L) evaluated for model media in stirred tanks, can also be used for cultivations in these reactors.

High-Order Model and Dynamic Filtering for Frame Rate Up-Conversion.

PubMed

Bao, Wenbo; Zhang, Xiaoyun; Chen, Li; Ding, Lianghui; Gao, Zhiyong

2018-08-01

This paper proposes a novel frame rate up-conversion method through high-order model and dynamic filtering (HOMDF) for video pixels. Unlike the constant brightness and linear motion assumptions in traditional methods, the intensity and position of the video pixels are both modeled with high-order polynomials in terms of time. Then, the key problem of our method is to estimate the polynomial coefficients that represent the pixel's intensity variation, velocity, and acceleration. We propose to solve it with two energy objectives: one minimizes the auto-regressive prediction error of intensity variation by its past samples, and the other minimizes video frame's reconstruction error along the motion trajectory. To efficiently address the optimization problem for these coefficients, we propose the dynamic filtering solution inspired by video's temporal coherence. The optimal estimation of these coefficients is reformulated into a dynamic fusion of the prior estimate from pixel's temporal predecessor and the maximum likelihood estimate from current new observation. Finally, frame rate up-conversion is implemented using motion-compensated interpolation by pixel-wise intensity variation and motion trajectory. Benefited from the advanced model and dynamic filtering, the interpolated frame has much better visual quality. Extensive experiments on the natural and synthesized videos demonstrate the superiority of HOMDF over the state-of-the-art methods in both subjective and objective comparisons.

Monte Carlo determination of the conversion coefficients Hp(3)/Ka in a right cylinder phantom with 'PENELOPE' code. Comparison with 'MCNP' simulations.

PubMed

Daures, J; Gouriou, J; Bordy, J M

2011-03-01

This work has been performed within the frame of the European Union ORAMED project (Optimisation of RAdiation protection for MEDical staff). The main goal of the project is to improve standards of protection for medical staff for procedures resulting in potentially high exposures and to develop methodologies for better assessing and for reducing, exposures to medical staff. The Work Package WP2 is involved in the development of practical eye-lens dosimetry in interventional radiology. This study is complementary of the part of the ENEA report concerning the calculations with the MCNP-4C code of the conversion factors related to the operational quantity H(p)(3). In this study, a set of energy- and angular-dependent conversion coefficients (H(p)(3)/K(a)), in the newly proposed square cylindrical phantom made of ICRU tissue, have been calculated with the Monte-Carlo code PENELOPE and MCNP5. The H(p)(3) values have been determined in terms of absorbed dose, according to the definition of this quantity, and also with the kerma approximation as formerly reported in ICRU reports. At a low-photon energy (up to 1 MeV), the two results obtained with the two methods are consistent. Nevertheless, large differences are showed at a higher energy. This is mainly due to the lack of electronic equilibrium, especially for small angle incidences. The values of the conversion coefficients obtained with the MCNP-4C code published by ENEA quite agree with the kerma approximation calculations obtained with PENELOPE. We also performed the same calculations with the code MCNP5 with two types of tallies: F6 for kerma approximation and *F8 for estimating the absorbed dose that is, as known, due to secondary electrons. PENELOPE and MCNP5 results agree for the kerma approximation and for the absorbed dose calculation of H(p)(3) and prove that, for photon energies larger than 1 MeV, the transport of the secondary electrons has to be taken into account.

Development of Monte Carlo simulations to provide scanner-specific organ dose coefficients for contemporary CT

NASA Astrophysics Data System (ADS)

Jansen, Jan T. M.; Shrimpton, Paul C.

2016-07-01

The ImPACT (imaging performance assessment of CT scanners) CT patient dosimetry calculator is still used world-wide to estimate organ and effective doses (E) for computed tomography (CT) examinations, although the tool is based on Monte Carlo calculations reflecting practice in the early 1990’s. Subsequent developments in CT scanners, definitions of E, anthropomorphic phantoms, computers and radiation transport codes, have all fuelled an urgent need for updated organ dose conversion factors for contemporary CT. A new system for such simulations has been developed and satisfactorily tested. Benchmark comparisons of normalised organ doses presently derived for three old scanners (General Electric 9800, Philips Tomoscan LX and Siemens Somatom DRH) are within 5% of published values. Moreover, calculated normalised values of CT Dose Index for these scanners are in reasonable agreement (within measurement and computational uncertainties of  ±6% and  ±1%, respectively) with reported standard measurements. Organ dose coefficients calculated for a contemporary CT scanner (Siemens Somatom Sensation 16) demonstrate potential deviations by up to around 30% from the surrogate values presently assumed (through a scanner matching process) when using the ImPACT CT Dosimetry tool for newer scanners. Also, illustrative estimates of E for some typical examinations and a range of anthropomorphic phantoms demonstrate the significant differences (by some 10’s of percent) that can arise when changing from the previously adopted stylised mathematical phantom to the voxel phantoms presently recommended by the International Commission on Radiological Protection (ICRP), and when following the 2007 ICRP recommendations (updated from 1990) concerning tissue weighting factors. Further simulations with the validated dosimetry system will provide updated series of dose coefficients for a wide range of contemporary scanners.

Electrodeposition Process and Performance of CuIn(Se x S1- x )2 Film for Absorption Layer of Thin-Film Solar Cells

NASA Astrophysics Data System (ADS)

Li, Libo; Yang, Xueying; Gao, Guanxiong; Wang, Wentao; You, Jun

2017-11-01

CuIn(Se x S1- x )2 thin film is prepared by the electrodeposition method for the absorption layer of the solar cell. The CuIn(Se x S1- x )2 films are characterized by cyclic voltammetry measurement for the reduction of copper, indium, selenium and sulfur in selenium and sulfur in aqueous solutions with sodium citrate and without sodium citrate. In the four cases, the defined reduction process for every single element is obtained and it is observed that sodium citrate changes the reduction potentials. A linear relationship between the current density of the reduction peak and (scan rate v)1/2 for copper and indium is achieved, indicating that the process is diffusion controlled. The diffusion coefficients of copper and indium ions are calculated. The diffusional coefficient D value of copper is higher than that of indium, and this is the reason why the deposition rate of copper is higher. When four elements are co-deposited in the aqueous solution with sodium citrate, the quaternary compound of CuIn(Se x S1- x )2 is deposited together with Cu3Se2 impure phases after annealing, as found by XRD spectra. Morphology is observed by SEM and AFM. The chemical state of the films components is analyzed by XPS. The UV-Visible spectrophotometer and electrochemistry workstation are employed to measure the photoelectric properties. The results show that the smooth, uniform and compact CuIn(Se x S1- x )2 film is a semiconductor with a band gap of 1.49 eV and a photovoltaic conversion efficiency of 0.45%.

Effect of borate glass composition on its conversion to hydroxyapatite and on the proliferation of MC3T3-E1 cells.

PubMed

Brown, Roger F; Rahaman, Mohamed N; Dwilewicz, Agatha B; Huang, Wenhai; Day, Delbert E; Li, Yadong; Bal, B Sonny

2009-02-01

Glasses containing varying amounts of B(2)O(3) were prepared by partially or fully replacing the SiO(2) in silicate 45S5 bioactive glass with B(2)O(3). The effects of the B(2)O(3) content of the glass on its conversion to hydroxyapatite (HA) and on the proliferation of MC3T3-E1 cells were investigated in vitro. Conversion of the glasses to HA in dilute (20 mM) K(2)HPO(4) solution was monitored using weight loss and pH measurements. Proliferation of MC3T3-E1 cells was determined qualitatively by assay of cell density at the glass interface after incubation for 1 day and 3 days, and quantitatively by fluorescent measurements of total DNA in cultures incubated for 4 days. Higher B(2)O(3) content of the glass increased the conversion rate to HA, but also resulted in a greater inhibition of cell proliferation under static culture conditions. For a given mass of glass in the culture medium, the inhibition of cell proliferation was alleviated by using glasses with lower B(2)O(3) content, by incubating the cell cultures under dynamic rather than static conditions, or by partially converting the glass to HA prior to cell culture.

Laser Cooling of Solids

DTIC Science & Technology

2009-01-01

BN2 − CN3 + (1− ηe)BN2 (9) Here α(ν,N) is the interband absorption coefficient that in- cludes many-body and blocking factors. The recombination...the reso- nant absorption coefficient and αb is the unwanted parasitic (background) absorption coefficient . As will be derived in sections II and IV... coefficient of αb. It is straightforward to evaluate the steady-state solution to the above rate equations by setting the time derivatives to zero

Transient Numerical Modeling of Catalytic Channels

NASA Technical Reports Server (NTRS)

Struk, Peter M.; Dietrich, Daniel L.; Miller, Fletcher J.; T'ien, James S.

2007-01-01

This paper presents a transient model of catalytic combustion suitable for isolated channels and monolith reactors. The model is a lumped two-phase (gas and solid) model where the gas phase is quasi-steady relative to the transient solid. Axial diffusion is neglected in the gas phase; lateral diffusion, however, is accounted for using transfer coefficients. The solid phase includes axial heat conduction and external heat loss due to convection and radiation. The combustion process utilizes detailed gas and surface reaction models. The gas-phase model becomes a system of stiff ordinary differential equations while the solid phase reduces, after discretization, into a system of stiff ordinary differential-algebraic equations. The time evolution of the system came from alternating integrations of the quasi-steady gas and transient solid. This work outlines the numerical model and presents some sensitivity studies on important parameters including internal transfer coefficients, catalytic surface site density, and external heat-loss (if applicable). The model is compared to two experiments using CO fuel: (1) steady-state conversion through an isothermal platinum (Pt) tube and (2) transient propagation of a catalytic reaction inside a small Pt tube. The model requires internal mass-transfer resistance to match the experiments at lower residence times. Under mass-transport limited conditions, the model reasonably predicted exit conversion using global mass-transfer coefficients. Near light-off, the model results did not match the experiment precisely even after adjustment of mass-transfer coefficients. Agreement improved for the first case after adjusting the surface kinetics such that the net rate of CO adsorption increased compared to O2. The CO / O2 surface mechanism came from a sub-set of reactions in a popular CH4 / O2 mechanism. For the second case, predictions improved for lean conditions with increased external heat loss or adjustment of the kinetics as in the first case. Finally, the results show that different initial surface-species distribution leads to different steady-states under certain conditions. These results demonstrate the utility of a lumped two-phase model of a transient catalytic combustor with detailed chemistry.

Multiple-Band Linear-Polarization Conversion and Circular Polarization in Reflection Mode Using a Symmetric Anisotropic Metasurface

NASA Astrophysics Data System (ADS)

Lin, Bao-Qin; Guo, Jian-Xin; Chu, Peng; Huo, Wen-Jun; Xing, Zhuo; Huang, Bai-Gang; Wu, Lan

2018-02-01

In this work, we propose a multiband linear-polarization (LP) conversion and circular polarization (CP) maintaining reflector using a symmetric anisotropic metasurface. The anisotropic metasurface is composed of a square array of a two-corner-cut square multiring disk printed on a grounded dielectric substrate, which is a symmetric structure with a pair of mutually perpendicular symmetric axes u and v along the ±45 ° directions with respect to the y -axis direction. The simulated results show that the reflector can realize LP conversion in five frequency bands at both x - and y -polarized incidence, the first four bands all have a certain bandwidth, and the fourth one, especially, is an ultrawideband. In addition, because of the symmetry of the reflector structure, the polarization state of a CP wave can be maintained after reflection, and the magnitude of the copolarized reflection coefficient at the CP incidence is just equal to that of the cross-polarized reflection coefficient at the x - and y -polarized incidence. We analyze the root cause of the multiband LP conversion and CP maintaining reflection, and carry out one experiment to verify the proposed reflector.

Mimic Carbonic Anhydrase Using Metal-Organic Frameworks for CO2 Capture and Conversion.

PubMed

Jin, Chaonan; Zhang, Sainan; Zhang, Zhenjie; Chen, Yao

2018-02-19

Carbonic anhydrase (CA) is a zinc-containing metalloprotein, in which the Zn active center plays the key role to transform CO 2 into carbonate. Inspired by nature, herein we used metal-organic frameworks (MOFs) to mimic CA for CO 2 conversion, on the basis of the structural similarity between the Zn coordination in MOFs and CA active center. The biomimetic activity of MOFs was investigated by detecting the hydrolysis of para-nitrophenyl acetate, which is a model reaction used to evaluate CA activity. The biomimetic materials (e.g., CFA-1) showed good catalytic activity, and excellent reusability, and solvent and thermal stability, which is very important for practical applications. In addition, ZIF-100 and CFA-1 were used to mimic CA to convert CO 2 gas, and exhibited good efficiency on CO 2 conversion compared with those of other porous materials (e.g., MCM-41, active carbon). This biomimetic study revealed a novel CO 2 treatment method. Instead of simply using MOFs to absorb CO 2 , ZIF-100 and CFA-1 were used to mimic CA for in situ CO 2 conversion, which provides a new prospect in the biological and industrial applications of MOFs.

Solubility and durability of cardanol derived plasticizers for soft PVC

NASA Astrophysics Data System (ADS)

Greco, Antonio; Ferrari, Francesca; Velardi, Rosario; Frigione, Mariaenrica; Maffezzoli, Alfonso

2015-12-01

This work is aimed to study the suitability of cardanol derivatives as primary plasticizer for PVC. The innovative plasticizer is obtained by chemical modification of cardanol, a natural, renewable resource, obtained as a by-product of the cashew nut shell industry. Cardanol derived plasticizers (CDP) were prepared by following various procedures, that allow obtaining different degrees of conversion of cardanol. Rheological and ageing tests were made on soft PVC produced by the addition of CDP;results obtained were compared to soft PVC attained by the use of di-ethyl-hexyl-phthalate (DEHP) and other natural derived plasticizers already used in PVC industry (epoxidated soybean oil, ESBO, and acetic acid ester, AAE).A high dependence on the degree of conversion was found: CDP with a good degree of conversion have similar gelation temperature and diffusion coefficient compared to DEHP based plastisols. Otherwise,CDP with a low degree of conversionshow a higher diffusion coefficient, index of a fast migration of the plasticizer from soft PVC.

Conversion of an atomic to a molecular argon ion and low pressure argon relaxation

NASA Astrophysics Data System (ADS)

M, N. Stankov; A, P. Jovanović; V, Lj Marković; S, N. Stamenković

2016-01-01

The dominant process in relaxation of DC glow discharge between two plane parallel electrodes in argon at pressure 200 Pa is analyzed by measuring the breakdown time delay and by analytical and numerical models. By using the approximate analytical model it is found that the relaxation in a range from 20 to 60 ms in afterglow is dominated by ions, produced by atomic-to-molecular conversion of Ar+ ions in the first several milliseconds after the cessation of the discharge. This conversion is confirmed by the presence of double-Gaussian distribution for the formative time delay, as well as conversion maxima in a set of memory curves measured in different conditions. Finally, the numerical one-dimensional (1D) model for determining the number densities of dominant particles in stationary DC glow discharge and two-dimensional (2D) model for the relaxation are used to confirm the previous assumptions and to determine the corresponding collision and transport coefficients of dominant species and processes. Project supported by the Ministry of Education, Science and Technological Development of the Republic of Serbia (Grant No. ON171025).

Managed grassland alters soil N dynamics and N2O emissions in temperate steppe.

PubMed

Xu, Lijun; Xu, Xingliang; Tang, Xuejuan; Xin, Xiaoping; Ye, Liming; Yang, Guixia; Tang, Huajun; Lv, Shijie; Xu, Dawei; Zhang, Zhao

2018-04-01

Reclamation of degraded grasslands as managed grasslands has been increasingly accelerated in recent years in China. Land use change affects soil nitrogen (N) dynamics and nitrous oxide (N 2 O) emissions. However, it remains unclear how large-scale grassland reclamation will impact the grassland ecosystem as a whole. Here, we investigated the effects of the conversion from native to managed grasslands on soil N dynamics and N2O emissions by field experiments in Hulunber in northern China. Soil (0-10cm), nitrate (NO 3 - ), ammonium (NH 4 + ), and microbial N were measured in plots in a temperate steppe (Leymus chinensis grassland) and two managed grasslands (Medicago sativa and Bromus inermis grasslands) in 2011 and 2012. The results showed conversion of L. chinensis grassland to M. sativa or B. inermis grasslands decreased concentrations of NO 3 - -N, but did not change NH 4 + -N. Soil microbial N was slightly decreased by the conversion of L. chinensis grassland to M. sativa, but increased by the conversion to B. inermis. The conversion of L. chinensis grassland to M. sativa (i.e., a legume grass) increased N 2 O emissions by 26.2%, while the conversion to the B. inermis (i.e., a non-legume grass) reduced N 2 O emissions by 33.1%. The conversion from native to managed grasslands caused large created variations in soil NO 3 - -N and NH 4 + -N concentrations. Net N mineralization rates did not change significantly in growing season or vegetation type, but to net nitrification rate. These results provide evidence on how reclamation may impact the grassland ecosystem in terms of N dynamics and N 2 O emissions. Copyright © 2017. Published by Elsevier B.V.

Chemical Potential Evaluation of Thermoelectric and Mechanical Properties of Zr2CoZ (Z = Si, Ge) Heusler Alloys

NASA Astrophysics Data System (ADS)

Yousuf, Saleem; Gupta, Dinesh C.

2018-04-01

The electronic, mechanical and thermoelectric properties of Zr2CoZ (Z = Si, Ge) Heusler alloys are investigated by the full-potential linearized augmented plane wave method. Using the Voigt-Reuss approximation, we calculated the various elastic constants, the shear and Young's moduli, and Poisson's ratio which predict the ductile nature of the alloys. Thermoelectric coefficients viz., Seebeck, electrical conductivity and figure of merit show Zr2CoZ alloys as n-type thermoelectric materials showing a linearly increasing Seebeck coefficient with temperature mainly because of the existence of almost flat conduction bands along L to D directions of a high symmetry Brillouin zone. The efficiency of conversion was measured as the figure of merit by taking into effect the lattice thermal part that achieves an upper-limit of 0.14 at 1200 K which may favour their use for waste heat recovery at higher temperatures.

The effect of modality and narration style on recall of online health information: results from a Web-based experiment.

PubMed

Bol, Nadine; van Weert, Julia C M; de Haes, Hanneke C J M; Loos, Eugene F; Smets, Ellen M A

2015-04-24

Older adults are increasingly using the Internet for health information; however, they are often not able to correctly recall Web-based information (eHealth information). Recall of information is crucial for optimal health outcomes, such as adequate disease management and adherence to medical regimes. Combining effective message strategies may help to improve recall of eHealth information among older adults. Presenting information in an audiovisual format using conversational narration style is expected to optimize recall of information compared to other combinations of modality and narration style. The aim of this paper is to investigate the effect of modality and narration style on recall of health information, and whether there are differences between younger and older adults. We conducted a Web-based experiment using a 2 (modality: written vs audiovisual information) by 2 (narration style: formal vs conversational style) between-subjects design (N=440). Age was assessed in the questionnaire and included as a factor: younger (<65 years) versus older (≥65 years) age. Participants were randomly assigned to one of four experimental webpages where information about lung cancer treatment was presented. A Web-based questionnaire assessed recall of eHealth information. Audiovisual modality (vs written modality) was found to increase recall of information in both younger and older adults (P=.04). Although conversational narration style (vs formal narration style) did not increase recall of information (P=.17), a synergistic effect between modality and narration style was revealed: combining audiovisual information with conversational style outperformed combining written information with formal style (P=.01), as well as written information with conversational style (P=.045). This finding suggests that conversational style especially increases recall of information when presented audiovisually. This combination of modality and narration style improved recall of information among both younger and older adults. We conclude that combining audiovisual information with conversational style is the best way to present eHealth information to younger and older adults. Even though older adults did not proportionally recall more when audiovisual information was combined with conversational style than younger adults, this study reveals interesting implications for improving eHealth information that is effective for both younger and older adults.

Deuterium transport in Cu, CuCrZr, and Cu/Be

NASA Astrophysics Data System (ADS)

Anderl, R. A.; Hankins, M. R.; Longhurst, G. R.; Pawelko, R. J.

This paper presents the results of deuterium implantation/permeation experiments and TMAP4 simulations for a CuCrZr alloy, for OFHC-Cu and for a Cu/Be bi-layered structure at temperatures from 700 to 800 K. Experiments used a mass-analyzed, 3-keV D 3+ ion beam with particle flux densities of 5 × 10 19 to 7 × 10 19 D/m 2 s. Effective diffusivities and surface molecular recombination coefficients were derived giving Arrhenius pre-exponentials and activation energies for each material: CuCrZr alloy, (2.0 × 10 -2 m 2/s, 1.2 eV) for diffusivity and (2.9 × x10 -14 m 4/s, 1.92 eV) for surface molecular recombination coefficients; OFHC Cu, (2.1 × 10 -6 m 2/s, 0.52 eV) for diffusivity and (9.1 × 10 -18 m 4/s, 0.99 eV) for surface molecular recombination coefficients. TMAP4 simulation of permeation data measured for a Cu/Be bi-layer sample was achieved using a four-layer structure (Cu/BeO interface/Be/BeO back surface) and recommended values for diffusivity and solubility in Be, BeO and Cu.

Clinical correlates of sex hormones in women: The study of health in Pomerania.

PubMed

Kische, Hanna; Gross, Stefan; Wallaschofski, Henri; Völzke, Henry; Dörr, Marcus; Nauck, Matthias; Haring, Robin

2016-09-01

Despite associations of sex hormones in women with increased cardiometabolic risk and mortality, the clinical correlates of altered sex hormone concentrations in women are less clearly understood. We investigated a broad range of clinical correlates of sex hormones in women from a large population-based sample. Data from 2560 women from two cohorts of the Study of Health in Pomerania were used. Stepwise multivariable regression models were implemented to investigate a broad range of behavioral, socio-demographic, and cardiometabolic clinical correlates related to total testosterone (TT), free testosterone (fT), androstenedione (ASD), dehydroepiandrosterone-sulfate (DHEAS), estrone (E1), estradiol (E2), and sex hormone-binding globulin (SHBG). Waist circumference and BMI (β-coefficient: -0.03; 95% CI: -0.04; 0.03) were inversely related to SHBG, and BMI was positively related to TT (β-coefficient: 0.005; 95% CI: 0.001; 0.009), fT, E1, and E2. Smoking was positively related to TT (β-coefficient: 0.04; 95% CI: 0.01; 0.06), ASD, and fT. Systolic blood pressure (TT: β-coefficient: 0.002; 95% CI: 0.001; 0.003), hypertension (TT: β-coefficient: 0.05; 95% CI: 0.003; 0.11), low-density lipoprotein (LDL) cholesterol (TT: β-coefficient: 0.02; 95% CI: 0.01; 0.05), and total cholesterol (TT: β-coefficient: -0.03; 95% CI: 0.01; 0.05) were positively related to TT and ASD. Finally, type 2 diabetes mellitus (T2DM), and metabolic syndrome (MetS) were positively related to fT, but inversely related to SHBG. Our population-based study, with sex hormone concentrations measured by liquid chromatography tandem mass spectrometry, revealed associations between clinical correlates including waist circumference, smoking, cohabitation, systolic blood pressure, cholesterol, and MetS with sex hormones. Thus, sex hormones and SHBG may play a role in the cardiovascular risk profile of women. Copyright © 2016 Elsevier Inc. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Dongwook; Vardon, Derek R.; Murali, Dheeptha

We demonstrate hydrothermal (300 degrees C, 10 MPa) catalytic conversion of real waste lipids (e.g., waste vegetable oil, sewer trap grease) to liquid hydrocarbon fuels without net need for external chemical inputs (e.g., H2 gas, methanol). A supported bimetallic catalyst (Pt-Re/C; 5 wt % of each metal) previously shown to catalyze both aqueous phase reforming of glycerol (a triacylglyceride lipid hydrolysis coproduct) to H2 gas and conversion of oleic and stearic acid, model unsaturated and saturated fatty acids, to linear alkanes was applied to process real waste lipid feedstocks in water. For reactions conducted with an initially inert headspace gasmore » (N2), waste vegetable oil (WVO) was fully converted into linear hydrocarbons (C15-C17) and other hydrolyzed byproducts within 4.5 h, and H2 gas production was observed. Addition of H2 to the initial reactor headspace accelerated conversion, but net H2 production was still observed, in agreement with results obtained for aqueous mixtures containing model fatty acids and glycerol. Conversion to liquid hydrocarbons with net H2 production was also observed for a range of other waste lipid feedstocks (animal fat residuals, sewer trap grease, dry distiller's grain oil, coffee oil residual). These findings demonstrate potential for valorization of waste lipids through conversion to hydrocarbons that are more compatible with current petroleum-based liquid fuels than the biodiesel and biogas products of conventional waste lipid processing technologies.« less

Performance Analysis of a Thermoelectric Solar Collector Integrated with a Heat Pump

NASA Astrophysics Data System (ADS)

Lertsatitthanakorn, C.; Jamradloedluk, J.; Rungsiyopas, M.; Therdyothin, A.; Soponronnarit, S.

2013-07-01

A novel heat pump system is proposed. A thermoelectric solar collector was coupled to a solar-assisted heat pump (TESC-HP) to work as an evaporator. The cooling effect of the system's refrigerant allowed the cold side of the system's thermoelectric modules to work at lower temperature, improving the conversion efficiency. The TESC-HP system mainly consisted of transparent glass, an air gap, an absorber plate that acted as a direct expansion-type collector/evaporator, an R-134a piston-type hermetic compressor, a water-cooled plate-type condenser, thermoelectric modules, and a water storage tank. Test results indicated that the TESC-HP has better coefficient of performance (COP) and conversion efficiency than the separate units. For the meteorological conditions in Mahasarakham, the COP of the TESC-HP system can reach 5.48 when the average temperature of 100 L of water is increased from 28°C to 40°C in 60 min with average ambient temperature of 32.5°C and average solar intensity of 815 W/m2, whereas the conversion efficiency of the TE power generator was around 2.03%.

Direct spectral evidence of single-axis rotation and ortho-hydrogen-assisted nuclear spin conversion of CH3F in solid para-hydrogen.

PubMed

Lee, Yuan-Pern; Wu, Yu-Jong; Hougen, Jon T

2008-09-14

Observation of two weak absorption lines from the E (K = 1) level and one intense feature from A (K = 0) for degenerate modes nu(4) and nu(6) of CH(3)F provides direct spectral evidence that CH(3)F isolated in p-H(2) rotates about only its symmetry axis, and not about the other two axes. An interaction between A and E vibrational levels caused by the partially hindered spinning rotation is proposed. Conversion of nuclear spin between A and E components of CH(3)F is rapid when p-H(2) contains some o-H(2), but becomes slow when the proportion of o-H(2) is much decreased.

[Effect of the thickness of reinforced glass ceramics on the degree of conversion of dual-cure resin cements].

PubMed

Zhu, Lin-Lin; Qiu, Li-Hong; Liu, Li-Yang; Li, Xiao-Lin

2017-10-01

To determine the effect of the thickness of reinforced glass ceramics on the degree of conversion (DC) of three dual-cure resin cements (Multilink N, RelyX Ultimate and NX3-Nexus). Upcera reinforced glass ceramics and IPS e.max CAD test specimen were processed, with different thickness, transmittance was tested by ultraviolet and visible spectrometer. The DC was evaluated using Fourier transform infrared (FT-IR) spectrometer, then the degree of conversion of polymerization before and after curing was calculated. SPSS 21.0 software package was used for data analysis. Transmittance decreased along with the thickness of reinforced glass ceramics increased. At 2 mm -thickness transmittance of upcera lithium disilicate glass ceramics was superior to IPS e.max CAD. The DC of dual-cured resin cement was decreased with the increase of thickness. At the same 2 mm group, the DC of Multilink N and RelyX Ultimate under upcera lithium disilicate glass ceramics were superior to that under IPS e.max CAD groups. At 2 mm-thickness transmittance of upcera lithium disilicate glass ceramics was superior to IPS e.max CAD. At the same 2 mm group, the DC of Multilink N and RelyX Ultimate under upcera lithium disilicate glass ceramics were superior to that under IPS e.max CAD groups.

An analytical two-flow model to simulate the distribution of irradiance in coastal waters with a wind-roughed surface and bottom reflectance

NASA Astrophysics Data System (ADS)

Ma, Wei-Ming

1997-06-01

An analytical two-flow model is derived from the radiative transfer equation to simulate the distribution of irradiance in coastal waters with a wind-roughed surface and bottom reflectance. The model utilizes unique boundary conditions, including the surface slope of the downwelling and upwelling irradiance as well as the influence of wind and bottom reflectance on simulated surface reflectance. The developed model provides a simple mathematical concept for understanding the irradiant light flux and associated processes in coastal or fresh water as well as turbid estuarine waters. The model is applied to data from the Banana River and coastal Atlantic Ocean water off the east coast of central Florida, USA. The two-flow irradiance model is capable of simulating realistic above-surface reflectance signatures under wind-roughened air-water surface given realistic input parameters including a specular flux conversion coefficient, absorption coefficient, backscattering coefficient, atmospheric visibility, bottom reflectance, and water depth. The root-mean-squared error of the calculated above-surface reflectances is approximately 3% in the Banana River and is less than 15% in coastal Atlantic Ocean off the east of Florida. Result of the subsurface reflectance sensitivity analysis indicates that the specular conversion coefficient is the most sensitive parameter in the model, followed by the beam attenuation coefficient, absorption coefficient, water depth, backscattering coefficient, specular irradiance, diffuse irradiance, bottom reflectance, and wind speed. On the other hand, result of the above-surface reflectance sensitivity analysis indicates that the wind speed is the most important parameter, followed by bottom reflectance, attenuation coefficient, water depth, conversion coefficient, specular irradiance, downwelling irradiance, absorption coefficient, and backscattering coefficient. Model results depend on the accuracy of these parameters to a large degree and more important the water depth and value of the bottom reflectance. The results of this work indicates little change of subsurface or in-water reflectances, due to variations of wind speed and observation angle. Simulations of the wind effect on the total downwelling irradiance from the two- flow model indicates that the total downwelling irradiance just below a wind-roughened water surface increases to about 1% of the total downwelling irradiance on a calm water surface when the sun is near zenith and increases to about 3% when the sun is near the horizon. This analytically based model, solved or developed utilizing the unique boundary conditions, can be applied to remote sensing of oceanic upper mixed layer dynamics, plant canopies, primary production, and shallow water environments with different bottom type reflectances. Future applications may include determining effects of sediment resuspension of bottom sediments in the bottom boundary layer on remotely sensed data.

The Mu2e crystal calorimeter

NASA Astrophysics Data System (ADS)

Happacher, F.

2017-09-01

The Mu2e Experiment at Fermilab will search for coherent, neutrino-less conversion of negative muons into electrons in the field of an Aluminum nucleus, μ- + Al → e- +Al. Data collection start is planned for the end of 2021. The dynamics of such charged lepton flavour violating (CLFV) process is well modelled by a two-body decay, resulting in a mono-energetic electron with an energy slightly below the muon rest mass. If no events are observed in three years of running, Mu2e will set an upper limit on the ratio between the conversion and the capture rates Rμ e = μ- + A(Z,N) → e- +A(Z,N)/μ- + A(Z,N) → νμ - +A(Z-1,N) of <= 6 × 10-17 (@ 90% C.L.). This will improve the current limit of four order of magnitudes with respect to the previous best experiment. Mu2e complements and extends the current search for μ → e γ decay at MEG as well as the direct searches for new physics at the LHC . The observation of such CLFV process could be clear evidence for New Physics beyond the Standard Model. Given its sensitivity, Mu2e will be able to probe New Physics at a scale inaccessible to direct searches at either present or planned high energy colliders. To search for the muon conversion process, a very intense pulsed beam of negative muons (~ 1010 μ/ sec) is stopped on an Aluminum target inside a very long solenoid where the detector is also located. The Mu2e detector is composed of a straw tube tracker and a CsI crystals electromagnetic calorimeter. An external veto for cosmic rays surrounds the detector solenoid. In 2016, Mu2e has passed the final approval stage from DOE and has started its construction phase. An overview of the physics motivations for Mu2e, the current status of the experiment and the required performances and design details of the calorimeter are presented.

The Mu2e crystal calorimeter

NASA Astrophysics Data System (ADS)

Atanov, N.; Budagov, J.; Cervelli, F.; Colao, F.; Cordelli, M.; Corradi, G.; Danè, E.; Davidov, Y.; Di Falco, S.; Diociaiuti, E.; Donati, S.; Donghia, R.; Echenard, B.; Giovannella, S.; Glagolev, V.; Grancagnolo, F.; Happacher, F.; Hitlin, D.; Martini, M.; Miscetti, S.; Miyashita, T.; Morescalchi, L.; Murat, P.; Pedreschi, E.; Pezzullo, G.; Porter, F.; Saputi, A.; Sarra, I.; Spinella, F.; Tassielli, G.; Mu2e Collaboration

2017-09-01

The Mu2e Experiment at Fermilab will search for coherent, neutrino-less conversion of negative muons into electrons in the field of an Aluminum nucleus, μ- + Al → e- +Al. Data collection start is planned for the end of 2021. The dynamics of such charged lepton flavour violating (CLFV) process is well modelled by a two-body decay, resulting in a mono-energetic electron with an energy slightly below the muon rest mass. If no events are observed in three years of running, Mu2e will set an upper limit on the ratio between the conversion and the capture rates Rμe = μ- + A(Z,N) → e- + A(Z,N)/μ- + A(Z,N) → νμ- + A(Z-1,N) of <= 6 × 10-17 (@ 90% C.L.). This will improve the current limit of four order of magnitudes with respect to the previous best experiment. Mu2e complements and extends the current search for μ → e γ decay at MEG as well as the direct searches for new physics at the LHC . The observation of such CLFV process could be clear evidence for New Physics beyond the Standard Model. Given its sensitivity, Mu2e will be able to probe New Physics at a scale inaccessible to direct searches at either present or planned high energy colliders. To search for the muon conversion process, a very intense pulsed beam of negative muons (~ 1010 μ/sec) is stopped on an Aluminum target inside a very long solenoid where the detector is also located. The Mu2e detector is composed of a straw tube tracker and a CsI crystals electromagnetic calorimeter. An external veto for cosmic rays surrounds the detector solenoid. In 2016, Mu2e has passed the final approval stage from DOE and has started its construction phase. An overview of the physics motivations for Mu2e, the current status of the experiment and the required performances and design details of the calorimeter are presented.

OH + (E)- and (Z)-1-chloro-3,3,3-trifluoropropene-1 (CF3CH═CHCl) reaction rate coefficients: stereoisomer-dependent reactivity.

PubMed

Gierczak, Tomasz; Baasandorj, M; Burkholder, James B

2014-11-20

Rate coefficients for the gas-phase reaction of the OH radical with (E)- and (Z)-CF3CH═CHCl (1-chloro-3,3,3-trifluoropropene-1, HFO-1233zd) (k1(T) and k2(T), respectively) were measured under pseudo-first-order conditions in OH over the temperature range 213-376 K. OH was produced by pulsed laser photolysis, and its temporal profile was measured using laser-induced fluorescence. The obtained rate coefficients were independent of pressure between 25 and 100 Torr (He, N2) with k1(296 K) = (3.76 ± 0.35) × 10(-13) cm(3) molecule(-1) s(-1) and k2(296 K) = (9.46 ± 0.85) × 10(-13) cm(3) molecule(-1) s(-1) (quoted uncertainties are 2σ and include estimated systematic errors). k2(T) showed a weak non-Arrhenius behavior over this temperature range. The (E)- and (Z)- stereoisomer rate coefficients were found to have opposite temperature dependencies that are well represented by k1(T) = (1.14 ± 0.15) × 10(-12) exp[(-330 ± 10)/T] cm(3) molecule(-1) s(-1) and k2(T) = (7.22 ± 0.65) × 10(-19) × T(2) × exp[(800 ± 20)/T] cm(3) molecule(-1) s(-1). The present results are compared with a previous room temperature relative rate coefficient study of k1, and an explanation for the discrepancy is presented. CF3CHO, HC(O)Cl, and CF3CClO, were observed as stable end-products following the OH radical initiated degradation of (E)- and (Z)-CF3CH═CHCl in the presence of O2. In addition, chemically activated isomerization was also observed. Atmospheric local lifetimes of (E)- and (Z)-CF3CH═CHCl, due to OH reactive loss, were estimated to be ∼34 and ∼11 days, respectively. Infrared absorption spectra measured in this work were used to estimate radiative efficiencies and well-mixed global warming potentials of ∼10 and ∼3 for (E)- and (Z)-CF3CH═CHCl, respectively, on the 100-year time horizon.

Assessment of Myeloperoxidase Activity by the Conversion of Hydroethidine to 2-Chloroethidium*

PubMed Central

Maghzal, Ghassan J.; Cergol, Katie M.; Shengule, Sudhir R.; Suarna, Cacang; Newington, Darren; Kettle, Anthony J.; Payne, Richard J.; Stocker, Roland

2014-01-01

Oxidants derived from myeloperoxidase (MPO) contribute to inflammatory diseases. In vivo MPO activity is commonly assessed by the accumulation of 3-chlorotyrosine (3-Cl-Tyr), although 3-Cl-Tyr is formed at low yield and is subject to metabolism. Here we show that MPO activity can be assessed using hydroethidine (HE), a probe commonly employed for the detection of superoxide. Using LC/MS/MS, 1H NMR, and two-dimensional NOESY, we identified 2-chloroethidium (2-Cl-E+) as a specific product when HE was exposed to hypochlorous acid (HOCl), chloramines, MPO/H2O2/chloride, and activated human neutrophils. The rate constant for HOCl-mediated conversion of HE to 2-Cl-E+ was estimated to be 1.5 × 105 m−1s−1. To investigate the utility of 2-Cl-E+ to assess MPO activity in vivo, HE was injected into wild-type and MPO-deficient (Mpo−/−) mice with established peritonitis or localized arterial inflammation, and tissue levels of 2-Cl-E+ and 3-Cl-Tyr were then determined by LC/MS/MS. In wild-type mice, 2-Cl-E+ and 3-Cl-Tyr were detected readily in the peritonitis model, whereas in the arterial inflammation model 2-Cl-E+ was present at comparatively lower concentrations (17 versus 0.3 pmol/mg of protein), and 3-Cl-Tyr could not be detected. Similar to the situation with 3-Cl-Tyr, tissue levels of 2-Cl-E+ were decreased substantially in Mpo−/− mice, indicative of the specificity of the assay. In the arterial inflammation model, 2-Cl-E+ was absent from non-inflamed arteries and blood, suggesting that HE oxidation occurred locally in the inflamed artery. Our data suggest that the conversion of exogenous HE to 2-Cl-E+ may be a useful selective and sensitive marker for MPO activity in addition to 3-Cl-Tyr. PMID:24436331

Conversion from rice to vegetable production increases N2O emission via increased soil organic matter mineralization.

PubMed

Wu, Lei; Tang, Shuirong; He, Dongdong; Wu, Xian; Shaaban, Muhammad; Wang, Milan; Zhao, Jingsong; Khan, Imran; Zheng, Xunhua; Hu, Ronggui; Horwath, William R

2017-04-01

The conversion from rice to vegetable production widely occurs in China. However, the effects of this conversion on N 2 O emission and the underlying mechanisms are not well understood. In the present study, 12 rice paddies (R) were selected and half of them converted to vegetable fields (V) with the following treatments: rice paddies without N-fertilizer (R-CK), rice paddies with conventional N-fertilizer (R-CN), converted vegetable fields without N-fertilizer (V-CK), and converted vegetable fields with conventional N-fertilizer (V-CN) in a randomized block design with 3 replicates. N 2 O emissions were measured with static chambers from December 2012 to December 2015. Within each V-CN plot, a root exclusion subplot was established to measure soil heterotrophic respiration (CO 2 effluxes), a proxy for soil organic matter mineralization. Conversion of rice paddies to vegetable production dramatically increased N 2 O emissions. The three-year cumulative N 2 O emissions were 0.59, 1.90, 55.50 and 160.14kg N ha -1 for R-CK, R-CN, V-CK and V-CN, respectively. The annual N 2 O emissions from vegetable fields ranged between 5.99 and 113.45kg N ha -1 yr -1 , with substantially higher emissions in the first year. N 2 O fluxes from V-CN were significantly and positively related to CO 2 fluxes and inorganic N concentrations. The linear relationship between natural logarithms of N 2 O and CO 2 fluxes was stronger and the regression coefficient higher in the first year, showing the dependence of N 2 O on soil organic matter mineralization. These results suggest that soil organic matter and N mineralization contributes significantly to N 2 O emission following conversion of rice paddies to vegetable production. Copyright © 2017 Elsevier B.V. All rights reserved.

Efficient Photothermoelectric Conversion in Lateral Topological Insulator Heterojunctions.

PubMed

Mashhadi, Soudabeh; Duong, Dinh Loc; Burghard, Marko; Kern, Klaus

2017-01-11

Tuning the electron and phonon transport properties of thermoelectric materials by nanostructuring has enabled improving their thermopower figure of merit. Three-dimensional topological insulators, including many bismuth chalcogenides, attract increasing attention for this purpose, as their topologically protected surface states are promising to further enhance the thermoelectric performance. While individual bismuth chalcogenide nanostructures have been studied with respect to their photothermoelectric properties, nanostructured p-n junctions of these compounds have not yet been explored. Here, we experimentally investigate the room temperature thermoelectric conversion capability of lateral heterostructures consisting of two different three-dimensional topological insulators, namely, the n-type doped Bi 2 Te 2 Se and the p-type doped Sb 2 Te 3 . Scanning photocurrent microscopy of the nanoplatelets reveals efficient thermoelectric conversion at the p-n heterojunction, exploiting hot carriers of opposite sign in the two materials. From the photocurrent data, a Seebeck coefficient difference of ΔS = 200 μV/K was extracted, in accordance with the best values reported for the corresponding bulk materials. Furthermore, it is in very good agreement with the value of ΔS = 185 μV/K obtained by DFT calculation taking into account the specific doping levels of the two nanostructured components.

Conversational Agents in E-Learning

NASA Astrophysics Data System (ADS)

Kerry, Alice; Ellis, Richard; Bull, Susan

This paper discusses the use of natural language or 'conversational' agents in e-learning environments. We describe and contrast the various applications of conversational agent technology represented in the e-learning literature, including tutors, learning companions, language practice and systems to encourage reflection. We offer two more detailed examples of conversational agents, one which provides learning support, and the other support for self-assessment. Issues and challenges for developers of conversational agent systems for e-learning are identified and discussed.

Image analysis and green tea color change kinetics during thin-layer drying.

PubMed

Shahabi, Mohammad; Rafiee, Shahin; Mohtasebi, Seyed Saeid; Hosseinpour, Soleiman

2014-09-01

This study was conducted to investigate the effect of air temperature and air flow velocity on kinetics of color parameter changes during hot-air drying of green tea, to obtain the best model for hot-air drying of green tea, to apply a computer vision system and to study the color changes during drying. In the proposed computer vision system system, at first RGB values of the images were converted into XYZ values and then to Commission International d'Eclairage L*a*b* color coordinates. The obtained color parameters of L*, a* and b* were calibrated with Hunter-Lab colorimeter. These values were also used for calculation of the color difference, chroma, hue angle and browning index. The values of L* and b* decreased, while the values of a* and color difference (ΔE*ab ) increased during hot-air drying. Drying data were fitted to three kinetic models. Zero, first-order and fractional conversion models were utilized to describe the color changes of green tea. The suitability of fitness was determined using the coefficient of determination (R (2)) and root-mean-square error. Results showed that the fraction conversion model had more acceptable fitness than the other two models in most of color parameters. © The Author(s) 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Tunable features of magnetoelectric transformers.

PubMed

Dong, Shuxiang; Zhai, Junyi; Priya, Shashank; Li, Jie-Fang; Viehland, Dwight

2009-06-01

We have found that magnetostrictive FeBSiC alloy ribbons laminated with piezoelectric Pb(Zr,Ti)O(3) fiber can act as a tunable transformer when driven under resonant conditions. These composites were also found to exhibit the strongest resonant magnetoelectric voltage coefficient of 750 V/cm-Oe. The tunable features were achieved by applying small dc magnetic biases of -5

Kinetics of Scheelite Conversion in Sulfuric Acid

NASA Astrophysics Data System (ADS)

Shen, Leiting; Li, Xiaobin; Zhou, Qiusheng; Peng, Zhihong; Liu, Guihua; Qi, Tiangui; Taskinen, Pekka

2018-02-01

Complete conversion of scheelite in H2SO4 solution plays a key role in exploration of cleaner technology for producing ammonium paratungstate. In this work, the factors influencing scheelite conversion were investigated experimentally to model its kinetics. The results indicated that the conversion rate increases with increasing temperature and reducing particle size, but is almost independent of stirring speed. Moreover, although the conversion rate increases with increasing initial H2SO4 concentration (≤ 1.25 mol/L), it decreases rapidly at 1.5 mol/L H2SO4 after 10 min due to formation of a H2WO4 layer. The experimental data agree quite well with the shrinking core model under chemical reaction control in ≤ 1.25 mol/L H2SO4 solution, and the kinetic equation was established as: 1- ( 1- α )^{ 1 / 3} = 2 2 2 5 4 6. 6\\cdot C_{{{H}_{ 2} {SO}_{ 4} }}^{ 1. 2 2 6} \\cdot r_{ 0}^{ - 1} \\cdot e^{{ - 3 9 2 6 0/RT}} \\cdot t (t, min). This work could contribute to better understanding of scheelite conversion in H2SO4 solution and development of a new route for ammonium paratungstate production.

High spin states in {sup 151,153}Pr, {sup 157}Sm, and {sup 93}Kr

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hwang, J. K.; Ramayya, A. V.; Hamilton, J. H.

2010-09-15

High spin states are observed for the first time in the neutron-rich nuclei {sup 151,153}Pr, {sup 157}Sm, and {sup 93}Kr from the spontaneous fission of {sup 252}Cf. Twenty new transitions in {sup 151}Pr, twelve in {sup 153}Pr, five in {sup 157}Sm, and four in {sup 93}Kr were identified by using x-ray(Pr/Sm)-{gamma}-{gamma} and {gamma}-{gamma}-{gamma} triple coincidences. From the measured total internal conversion coefficients {alpha}{sub T} of four low-energy transitions in {sup 151,153}Pr, we determine that two bands in each nucleus have opposite parity. The interlacing E1 transitions between the bands suggest a form of parity doubling in {sup 151,153}Pr. New bandsmore » in {sup 157}Sm and {sup 93}Kr are reported. The half-life of the 354.8 keV state in {sup 93}Kr is measured to be 10(2) ns.« less

Enhanced photovoltaic property by forming p-i-n structures containing Si quantum dots/SiC multilayers

PubMed Central

2014-01-01

Si quantum dots (Si QDs)/SiC multilayers were fabricated by annealing hydrogenated amorphous Si/SiC multilayers prepared in a plasma-enhanced chemical vapor deposition system. The thickness of amorphous Si layer was designed to be 4 nm, and the thickness of amorphous SiC layer was kept at 2 nm. Transmission electron microscopy observation revealed the formation of Si QDs after 900°C annealing. The optical properties of the Si QDs/SiC multilayers were studied, and the optical band gap deduced from the optical absorption coefficient result is 1.48 eV. Moreover, the p-i-n structure with n-a-Si/i-(Si QDs/SiC multilayers)/p-Si was fabricated, and the carrier transportation mechanism was investigated. The p-i-n structure was used in a solar cell device. The cell had the open circuit voltage of 532 mV and the power conversion efficiency (PCE) of 6.28%. PACS 81.07.Ta; 78.67.Pt; 88.40.jj PMID:25489285

Experimental Investigations of Direct and Converse Flexoelectric Effect in Bilayer Lipid Membranes.

NASA Astrophysics Data System (ADS)

Todorov, Angelio Todorov

Flexoelectric coefficients (direct and converse), electric properties (capacitance and resistivity) and mechanical properties (thickness and elastic coefficients) have been determined for bilayer lipid membranes (BLMs) prepared from egg yolk lecithin (EYL), glycerol monoleate (GMO), phosphatidyl choline (PC) and phosphatidyl serine (PS) as a function of frequency, pH and surface charge modifiers. Direct flexoelectric effect manifested itself in the development of microvolt range a.c. potential (U_{f}) upon subjecting one side of a BLM to an oscillating hydrostatic pressure, in the 100-1000 Hz range. Operationally, the flexoelectric coefficient (f) is expressed by the ratio between U_{f} and the change of curvature (c) which accompanied the flexing of the membrane. Membrane curvature was determined by means of either the electric method (capacitance microphone effect) or by the newly developed method of stroboscopic interferometry. Real-time stroboscopic interferometry coupled with simultaneous electric measurements, provided a direct method for the determination of f. Two different frequency regimes of f were recognized. At low frequencies (<300 Hz), associated with free mobility of the surfactant, f-values of 24.1 times 10^{-19} and 0.87 times 10^ {-19} Coulombs were obtained for PC and GMO BLMs. At high frequencies (>300 Hz), associated with blocked mobility of the surfactant, f-values of 16.5 times 10^ {-19} and 0.30 times 10^{-19} Coulombs were obtained for PC and GMO BLMs. The theoretically calculated value for the GMO BLM oscillating at high frequency (0.12 times 10^{-19 } Coulombs) agreed well with that determined experimentally (0.3 times 10 ^{-19} Coulombs). For charged bovine brain PS BLM the observed flexocoefficient was f = 4.0 times 10^{ -18} Coulombs. Converse flexoelectric effect manifested itself in voltage-induced BLM curvature. Observations were carried out on uranyl acetate (UA) stabilized PS BLM under a.c. excitation. Frequency dependence of f was revealed by means of real-time stroboscopic interferometry. Satisfactory agreement was observed between the direct and converse f-values, measured. Thus, both manifestations of flexoelectricity in BLMs have now received experimental confirmation. Theories developed in this dissertation (as well as those described previously) have been compared with and contrasted to the experimentally determined direct and converse flexoelectric coefficients.

Comparison of conversion coefficients for equivalent dose in terms of air kerma for photons using a male adult voxel simulator in sitting and standing posture with geometry of irradiation antero-posterior

NASA Astrophysics Data System (ADS)

Galeano, D. C.; Cavalcante, F. R.; Carvalho, A. B.; Hunt, J.

2014-02-01

The dose conversion coefficient (DCC) is important to quantify and assess effective doses associated with medical, professional and public exposures. The calculation of DCCs using anthropomorphic simulators and radiation transport codes is justified since in-vivo measurement of effective dose is extremely difficult and not practical for occupational dosimetry. DCCs have been published by the ICRP using simulators in a standing posture, which is not always applicable to all exposure scenarios, providing an inaccurate dose estimation. The aim of this work was to calculate DCCs for equivalent dose in terms of air kerma (H/Kair) using the Visual Monte Carlo (VMC) code and the VOXTISS8 adult male voxel simulator in sitting and standing postures. In both postures, the simulator was irradiated by a plane source of monoenergetic photons in antero-posterior (AP) geometry. The photon energy ranged from 15 keV to 2 MeV. The DCCs for both postures were compared and the DCCs for the standing simulator were higher. For certain organs, the difference of DCCs were more significant, as in gonads (48% higher), bladder (16% higher) and colon (11% higher). As these organs are positioned in the abdominal region, the posture of the anthropomorphic simulator modifies the form in which the radiation is transported and how the energy is deposited. It was also noted that the average percentage difference of conversion coefficients was 33% for the bone marrow, 11% for the skin, 13% for the bone surface and 31% for the muscle. For other organs, the percentage difference of the DCCs for both postures was not relevant (less than 5%) due to no anatomical changes in the organs of the head, chest and upper abdomen. We can conclude that is important to obtain DCCs using different postures from those present in the scientific literature.

Characteristics of low-slope streams that affect O2 transfer rates

USGS Publications Warehouse

Parker, Gene W.; Desimone, Leslie A.

1991-01-01

Multiple-regression techniques were used to derive the reaeration coefficients estimating equation for low sloped streams: K2 = 3.83 MBAS-0.41 SL0.20 H-0.76, where K2 is the reaeration coefficient in base e units per day; MBAS is the methylene blue active substances concentration in milligrams per liter; SL is the water-surface slope in foot per foot; and H is the mean-flow depth in feet. Fourteen hydraulic, physical, and water-quality characteristics were regressed against 29 measured-reaeration coefficients for low-sloped (water surface slopes less than 0.002 foot per foot) streams in Massachusetts and New York. Reaeration coefficients measured from May 1985 to October 1988 ranged from 0.2 to 11.0 base e units per day for 29 low-sloped tracer studies. Concentration of methylene blue active substances is significant because it is thought to be an indicator of concentration of surfactants which could change the surface tension at the air-water interface.

Tabulation of hybrid theory calculated e-N2 vibrational and rotational cross sections

NASA Technical Reports Server (NTRS)

Chandra, N.; Temkin, A.

1976-01-01

Vibrational excitation cross sections of N2 by electron impact are tabulated. Integrated cross sections are given for transitions v yields v prime where o=or v=or 8 in the energy range 0.1 eV=or E=or 10 eV. The energy grid is chosen to be most dense in the resonance region (2 to 4 eV) so that the substructure is present in the numerical results. Coefficients in the angular distribution formula (differential scattering cross section) for transitions v=0 yields v prime = or 8 are also numerically given over the same grid of energies. Simultaneous rotation-vibration coefficients are also given for transitions v=o,j=o; 1 yields v prime=o, j=o,2,4; 1,3,5. All results are obtained from the hybrid theory.

Fuel Breeding and Core Behavior Analyses on In Core Fuel Management of Water Cooled Thorium Reactors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Permana, Sidik; Department of Physics, Bandung Institute of Technology, Gedung Fisika, Jl. Ganesha 10, Bandung 40132; Sekimoto, Hiroshi

2010-12-23

Thorium fuel cycle with recycled U-233 has been widely recognized having some contributions to improve the water-cooled breeder reactor program which has been shown by a feasible area of breeding and negative void reactivity which confirms that fissile of 233U contributes to better fuel breeding and effective for obtaining negative void reactivity coefficient as the main fissile material. The present study has the objective to estimate the effect of whole core configuration as well as burnup effects to the reactor core profile by adopting two dimensional model of fuel core management. About more than 40 months of cycle period hasmore » been employed for one cycle fuel irradiation of three batches fuel system for large water cooled thorium reactors. All position of fuel arrangement contributes to the total core conversion ratio which gives conversion ratio less than unity of at the BOC and it contributes to higher than unity (1.01) at the EOC after some irradiation process. Inner part and central part give the important part of breeding contribution with increasing burnup process, while criticality is reduced with increasing the irradiation time. Feasibility of breeding capability of water-cooled thorium reactors for whole core fuel arrangement has confirmed from the obtained conversion ratio which shows higher than unity. Whole core analysis on evaluating reactivity change which is caused by the change of voided condition has been employed for conservative assumption that 100% coolant and moderator are voided. It obtained always a negative void reactivity coefficient during reactor operation which shows relatively more negative void coefficient at BOC (fresh fuel composition), and it becomes less negative void coefficient with increasing the operation time. Negative value of void reactivity coefficient shows the reactor has good safety properties in relation to the reactivity profile which is the main parameter in term of criticality safety analysis. Therefore, this evaluation has confirmed that breeding condition and negative coefficient can be obtained simultaneously for water-cooled thorium reactor obtains based on the whole core fuel arrangement.« less

Effect of acid hydrolysis and fungal biotreatment on agro-industrial wastes for obtainment of free sugars for bioethanol production.

PubMed

El-Tayeb, T S; Abdelhafez, A A; Ali, S H; Ramadan, E M

2012-10-01

This study was designed to evaluate selected chemical and microbiological treatments for the conversion of certain local agro-industrial wastes (rice straw, corn stalks, sawdust, sugar beet waste and sugarcane bagasse) to ethanol. The chemical composition of these feedstocks was determined. Conversion of wastes to free sugars by acid hydrolysis varied from one treatment to another. In single-stage dilute acid hydrolysis, increasing acid concentration from 1 % (v/v) to 5 % (v/v) decreased the conversion percentage of almost all treated agro-industrial wastes. Lower conversion percentages for some treatments were obtained when increasing the residence time from 90 to 120 min. The two-stage dilute acid hydrolysis by phosphoric acid (1.0 % v/v) followed by sulphuric acid (1.0 % v/v) resulted in the highest conversion percentage (41.3 % w/w) on treated sugar beet waste. This treatment when neutralized, amended with some nutrients and inoculated with baker's yeast, achieved the highest ethanol concentration (1.0 % v/v). Formation of furfural and hydroxymethylfurfural (HMF) were functions of type of acid hydrolysis, acid concentration, residence time and feedstock type. The highest bioconversion of 5 % wastes (37.8 % w/w) was recorded on sugar beet waste by Trichoderma viride EMCC 107. This treatment when followed by baker's yeast fermentation, 0.41 % (v/v) ethanol and 8.2 % (v/w) conversion coefficient were obtained.

Effect of acid hydrolysis and fungal biotreatment on agro-industrial wastes for obtainment of free sugars for bioethanol production

PubMed Central

El-Tayeb, T.S.; Abdelhafez, A.A.; Ali, S.H.; Ramadan, E.M.

2012-01-01

This study was designed to evaluate selected chemical and microbiological treatments for the conversion of certain local agro-industrial wastes (rice straw, corn stalks, sawdust, sugar beet waste and sugarcane bagasse) to ethanol. The chemical composition of these feedstocks was determined. Conversion of wastes to free sugars by acid hydrolysis varied from one treatment to another. In single-stage dilute acid hydrolysis, increasing acid concentration from 1 % (v/v) to 5 % (v/v) decreased the conversion percentage of almost all treated agro-industrial wastes. Lower conversion percentages for some treatments were obtained when increasing the residence time from 90 to 120 min. The two-stage dilute acid hydrolysis by phosphoric acid (1.0 % v/v) followed by sulphuric acid (1.0 % v/v) resulted in the highest conversion percentage (41.3 % w/w) on treated sugar beet waste. This treatment when neutralized, amended with some nutrients and inoculated with baker’s yeast, achieved the highest ethanol concentration (1.0 % v/v). Formation of furfural and hydroxymethylfurfural (HMF) were functions of type of acid hydrolysis, acid concentration, residence time and feedstock type. The highest bioconversion of 5 % wastes (37.8 % w/w) was recorded on sugar beet waste by Trichoderma viride EMCC 107. This treatment when followed by baker’s yeast fermentation, 0.41 % (v/v) ethanol and 8.2 % (v/w) conversion coefficient were obtained. PMID:24031984

40 CFR 63.626 - Performance tests and compliance provisions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... affected facility. P = equivalent P2O5 feed rate, metric ton/hr (ton/hr). K = conversion factor, 1000 mg/g... P2O5 stored, metric tons (tons). K = conversion factor, 1000 mg/g (453,600 mg/lb). (ii) Method 13A or... Where: E = emission rate of total fluorides, g/metric ton (lb/ton) of equivalent P2O5 feed. Csi...

40 CFR 63.626 - Performance tests and compliance provisions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... affected facility. P = equivalent P2O5 feed rate, metric ton/hr (ton/hr). K = conversion factor, 1000 mg/g... P2O5 stored, metric tons (tons). K = conversion factor, 1000 mg/g (453,600 mg/lb). (ii) Method 13A or... Where: E = emission rate of total fluorides, g/metric ton (lb/ton) of equivalent P2O5 feed. Csi...

40 CFR 63.626 - Performance tests and compliance provisions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... affected facility. P = equivalent P2O5 feed rate, metric ton/hr (ton/hr). K = conversion factor, 1000 mg/g... P2O5 stored, metric tons (tons). K = conversion factor, 1000 mg/g (453,600 mg/lb). (ii) Method 13A or... Where: E = emission rate of total fluorides, g/metric ton (lb/ton) of equivalent P2O5 feed. Csi...

DOE Office of Scientific and Technical Information (OSTI.GOV)

S.A. Feshchenko; V.I. Pleshkov; I.N. Shishchuk

To reduce the costs of blast-furnace smelting, the Svobodnyi Sokol plant has devised a comprehensive program of organizational-technical measures that include study of ways of reducing coke consumption. To do this, the plant began operating its blast furnaces with schungite when making foundry and conversion pig irons. Using schungite in the charge employed to make foundry iron makes it possible to save a significant (10-15%) amount of coke. The value of the coefficient that characterizes the replacement of coke by schungite varies broadly and can reach 1.0 or more, depending on the grade of iron being made and the furnacemore » operating regime. The same coefficient has a value of 0.57 kg coke/kg schungite when 12-15 kg schungite/ton pig is used to make conversion pig iron.« less

A new combined green method for 2-Chlorophenol removal using cross-linked Brassica rapa peroxidase in silicone oil.

PubMed

Tandjaoui, Nassima; Abouseoud, Mahmoud; Couvert, Annabelle; Amrane, Abdeltif; Tassist, Amina

2016-04-01

This study proposes a new technique to treat waste air containing 2-Chlorophenol (2-CP), namely an integrated process coupling absorption of the compound in an organic liquid phase and its enzymatic degradation. Silicone oil (47V20) was used as an organic absorbent to allow the volatile organic compound (VOC) transfer from the gas phase to the liquid phase followed by its degradation by means of Cross-linked Brassica rapa peroxidase (BRP) contained in the organic phase. An evaluation of silicone oil (47V20) absorption capacity towards 2-CP was first accomplished by determining its partition coefficient (H) in this solvent. The air-oil partition coefficient of 2-CP was found equal to 0.136 Pa m(3) mol(-1), which is five times lower than the air-water value (0.619 Pam(3) mol(-1)). The absorbed 2-CP was then subject to enzymatic degradation by cross-linked BRP aggregates (BRP-CLEAs). The degradation step was affected by four parameters (contact time; 2-CP, hydrogen peroxide and enzyme concentrations), which were optimized in order to obtain the highest conversion yield. A maximal conversion yield of 69% and a rate of 1.58 mg L(-1) min(-1)were obtained for 100 min duration time when 2-CP and hydrogen peroxide concentrations were respectively 80 mg L(-1) and 6 mM in the presence of 2.66 UI mL(-1) BRP-CLEAs. The reusability of BRP-CLEAs in silicone oil was assessed, showing promising results since 59% of their initial efficiency remained after three batches. Copyright © 2016 Elsevier Ltd. All rights reserved.

Present state of boron-carbon thermoelectric materials

NASA Technical Reports Server (NTRS)

Elsner, N. B.; Reynolds, G. H.

1983-01-01

Boron-carbon p-type thermoelectric materials show promise for use in advanced thermal-to-electric space power conversion systems. Here, recent data on the thermoelectric properties of boron-carbon materials, such as B9C, B13C2, B15C2, and B4C, are reviewed. In particular, attention is given to the effect of the compositional homogeneity and residual impurity content on the Seeback coefficient, electrical resistivity, and thermal conductivity of these materials. The effect of carbon content for a given level of impurity and degree of homogeneity is also discussed.

Spectral line narrowing in PPLN OPO devices for 1-μm wavelength doubling

NASA Astrophysics Data System (ADS)

Perrett, Brian J.; Terry, Jonathan A. C.; Mason, Paul D.; Orchard, David A.

2004-12-01

One route to generating mid-infrared (mid-IR) radiation is through a two-stage non-linear conversion process from the near-IR, exploiting powerful neodymium lasers operating at wavelengths close to 1 μm. In the first stage of this process non-linear conversion within a degenerate optical parametric oscillator (OPO) is used to double the wavelength of the 1 μm laser. The resultant 2 μm radiation is then used to pump a second OPO, based on a material such as ZGP, for conversion into the 3 to 5 μm mid-IR waveband. Periodically poled lithium niobate (PPLN) is a useful material for conversion from 1 to 2 μm due to its high non-linear coefficient (deff ~ 16 pm/V) and the long crystal lengths available (up to 50 mm). Slope efficiencies in excess of 40% have readily been achieved using a simple plane-plane resonator when pumped at 10 kHz with 3.5 mJ pulses from a 1.047 μm Nd:YLF laser. However, the OPO output was spectrally broad at degeneracy with a measured full-width-half-maximum (FWHM) linewidth of approximately 65 nm. This output linewidth is significantly broader than the spectral acceptance bandwidth of ZGP for conversion into the mid-IR. In this paper techniques for spectral narrowing the output from a degenerate PPLN OPO are investigated using two passive elements, a diffraction grating and an air spaced etalon. Slope efficiencies approaching 20% have been obtained using the grating in a dog-leg cavity configuration producing spectrally narrow 2 μm output with linewidths as low as 2 nm. A grating-narrowed degenerate PPLN OPO has been successfully used to pump a ZGP OPO.

Divergence of the long-wavelength collective diffusion coefficient in quasi-one- and quasi-two-dimensional colloidal suspensions.

PubMed

Lin, Binhua; Cui, Bianxiao; Xu, Xinliang; Zangi, Ronen; Diamant, Haim; Rice, Stuart A

2014-02-01

We report the results of experimental studies of the short-time-long-wavelength behavior of collective particle displacements in quasi-one-dimensional (q1D) and quasi-two-dimensional (q2D) colloid suspensions. Our results are reported via the q → 0 behavior of the hydrodynamic function H(q) that relates the effective collective diffusion coefficient D(e)(q), with the static structure factor S(q) and the self-diffusion coefficient of isolated particles D(0): H(q) ≡ D(e)(q)S(q)/D(0). We find an apparent divergence of H(q) as q → 0 with the form H(q) ∝ q(-γ) (1.7 < γ < 1.9) for both q1D and q2D colloid suspensions. Given that S(q) does not diverge as q → 0 we infer that D(e)(q) does. This behavior is qualitatively different from that of the three-dimensional H(q) and D(e)(q) as q → 0, and the divergence is of a different functional form from that predicted for the diffusion coefficient in one-component one-dimensional and two-dimensional fluids not subject to boundary conditions that define the dimensionality of the system. We provide support for the contention that the boundary conditions that define a confined system play a very important role in determining the long-wavelength behavior of the collective diffusion coefficient from two sources: (i) the results of simulations of H(q) and D(e)(q) in quasi-1D and quasi-2D systems and (ii) verification, using data from the work of Lin, Rice and Weitz [Phys. Rev. E 51, 423 (1995)], of the prediction by Bleibel et al., arXiv:1305.3715, that D(e)(q) for a monolayer of colloid particles constrained to lie in the interface between two fluids diverges as q(-1) as q → 0.

Rate Coefficient Measurements and Theoretical Analysis of the OH + ( E)-CF3CH═CHCF3 Reaction.

PubMed

Baasandorj, Munkhbayar; Marshall, Paul; Waterland, Robert L; Ravishankara, A R; Burkholder, James B

2018-05-04

Rate coefficients, k, for the gas-phase reaction of the OH radical with ( E)-CF 3 CH═CHCF 3 (( E)-1,1,1,4,4,4-hexafluoro-2-butene, HFO-1336mzz(E)) were measured over a range of temperatures (211-374 K) and bath gas pressures (20-300 Torr; He, N 2 ) using a pulsed laser photolysis-laser-induced fluorescence (PLP-LIF) technique. k 1 ( T) was independent of pressure over this range of conditions with k 1 (296 K) = (1.31 ± 0.15) × 10 -13 cm 3 molecule -1 s -1 and k 1 ( T) = (6.94 ± 0.80) × 10 -13 exp[-(496 ± 10)/ T] cm 3 molecule -1 s -1 , where the uncertainties are 2σ, and the pre-exponential term includes estimated systematic error. Rate coefficients for the OD reaction were also determined over a range of temperatures (262-374 K) at 100 Torr (He). The OD rate coefficients were ∼15% greater than the OH values and showed similar temperature dependent behavior with k 2 ( T) = (7.52 ± 0.44) × 10 -13 exp[-(476 ± 20)/ T] and k 2 (296 K) = (1.53 ± 0.15) × 10 -13 cm 3 molecule -1 s -1 . The rate coefficients for reaction 1 were also measured using a relative rate technique between 296 and 375 K with k 1 (296 K) measured to be (1.22 ± 0.1) × 10 -13 cm 3 molecule -1 s -1 , in agreement with the PLP-LIF results. In addition, the 296 K rate coefficient for the O 3 + ( E)-CF 3 CH═CHCF 3 reaction was determined to be <5.2 × 10 -22 cm 3 molecule -1 s -1 . A theoretical computational analysis is presented to interpret the observed positive temperature dependence for the addition reaction and the significant decrease in OH reactivity compared to the ( Z)-CF 3 CH═CHCF 3 stereoisomer reaction. The estimated atmospheric lifetime of ( E)-CF 3 CH═CHCF 3 , due to loss by reaction with OH, is estimated to be ∼90 days, while the actual lifetime will depend on the location and season of its emission. Infrared absorption spectra of ( E)-CF 3 CH═CHCF 3 were measured and used to estimate the 100 year time horizon global warming potentials (GWP) of 32 (atmospherically well-mixed) and 14 (lifetime-adjusted).

Zero TE-based pseudo-CT image conversion in the head and its application in PET/MR attenuation correction and MR-guided radiation therapy planning.

PubMed

Wiesinger, Florian; Bylund, Mikael; Yang, Jaewon; Kaushik, Sandeep; Shanbhag, Dattesh; Ahn, Sangtae; Jonsson, Joakim H; Lundman, Josef A; Hope, Thomas; Nyholm, Tufve; Larson, Peder; Cozzini, Cristina

2018-02-18

To describe a method for converting Zero TE (ZTE) MR images into X-ray attenuation information in the form of pseudo-CT images and demonstrate its performance for (1) attenuation correction (AC) in PET/MR and (2) dose planning in MR-guided radiation therapy planning (RTP). Proton density-weighted ZTE images were acquired as input for MR-based pseudo-CT conversion, providing (1) efficient capture of short-lived bone signals, (2) flat soft-tissue contrast, and (3) fast and robust 3D MR imaging. After bias correction and normalization, the images were segmented into bone, soft-tissue, and air by means of thresholding and morphological refinements. Fixed Hounsfield replacement values were assigned for air (-1000 HU) and soft-tissue (+42 HU), whereas continuous linear mapping was used for bone. The obtained ZTE-derived pseudo-CT images accurately resembled the true CT images (i.e., Dice coefficient for bone overlap of 0.73 ± 0.08 and mean absolute error of 123 ± 25 HU evaluated over the whole head, including errors from residual registration mismatches in the neck and mouth regions). The linear bone mapping accounted for bone density variations. Averaged across five patients, ZTE-based AC demonstrated a PET error of -0.04 ± 1.68% relative to CT-based AC. Similarly, for RTP assessed in eight patients, the absolute dose difference over the target volume was found to be 0.23 ± 0.42%. The described method enables MR to pseudo-CT image conversion for the head in an accurate, robust, and fast manner without relying on anatomical prior knowledge. Potential applications include PET/MR-AC, and MR-guided RTP. © 2018 International Society for Magnetic Resonance in Medicine.

Synthesis of Ferroelectric Lead Titanate Nanohoneycomb Arrays via Lead Supplement Process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Bongsoo; Hong, Seungbum; Ahn, Gun

In this paper, we demonstrate a novel process to convert TiO 2 nanotubes into ferroelectric nanohoneycombs, comprised of vertically aligned PbTiO 3 nanotubes. Tube bottom opening process enabled effective infiltration of lead acetate precursor into the nanotubes. Finally, nanohoneycombs, which were converted via additional lead supplement process, showed uniform conversion and well-defined ferroelectric properties with the effective piezoelectric coefficient of approximately 20 pm/V, which was measured by piezoresponse force microscopy.

Synthesis of Ferroelectric Lead Titanate Nanohoneycomb Arrays via Lead Supplement Process

DOE PAGES

Kim, Bongsoo; Hong, Seungbum; Ahn, Gun; ...

2016-05-14

In this paper, we demonstrate a novel process to convert TiO 2 nanotubes into ferroelectric nanohoneycombs, comprised of vertically aligned PbTiO 3 nanotubes. Tube bottom opening process enabled effective infiltration of lead acetate precursor into the nanotubes. Finally, nanohoneycombs, which were converted via additional lead supplement process, showed uniform conversion and well-defined ferroelectric properties with the effective piezoelectric coefficient of approximately 20 pm/V, which was measured by piezoresponse force microscopy.

Opportunities for HIV Prevention Communication During Sexual Encounters with Black Men Who Have Sex with Men.

PubMed

Aholou, Tiffiany M; Nanin, Jose; Drumhiller, Kathryn; Sutton, Madeline Y

2017-01-01

Conversations about HIV prevention before engaging in sex may result in safer sex practices and decreased HIV transmission. However, partner communication for HIV prevention has been understudied among black/African American men who have sex with men (BMSM), a group that is disproportionately affected by HIV. We explored and described encounters and perceptions about HIV prevention conversations among BMSM and their sex partner(s) in New York City. We conducted an inductive thematic analysis of semi-structured interviews with BMSM who reported sex with a man in the previous 3 months. Interviews were professionally transcribed; Nvivo was used for data analysis. Twenty-two BMSM were included in this analysis; median age = 29.1 years; 71.4% self-identified as MSM; 85.7% were ever HIV tested; and 52.6% reported no disclosure or discussion about HIV status with their previous sex partner. The main themes were: (1) missed opportunities for HIV prevention conversations (e.g., no HIV prevention conversations or HIV prevention conversations after sex had occurred); (2) barriers to HIV prevention conversations (e.g., being in the moment; not wanting to pause); (3) emotional thoughts after sex (e.g., feeling worried about possible HIV exposure); and (4) rethinking relationships and sexual health (e.g., changed sex practices by asking partners' HIV status before sex; started using condoms). These findings offer insight into HIV prevention conversations by BMSM around the time of or during sexual encounters and may inform and strengthen partner-level HIV prevention communication interventions for BMSM.

Negative optical absorption and up-energy conversion in dendrites of nanostructured silver grafted with α/β-poly(vinylidene fluoride) in small hierarchical structures

NASA Astrophysics Data System (ADS)

Phule, A. D.; Ram, S.; Shinde, S. K.; Choi, J. H.; Tyagi, A. K.

2018-04-01

We report that a negative optical absorption arises in a sharp band at 325 nm (energy hν2) in a nanostructured silver (n-Ag) doped poly(vinylidene fluoride) (PVF2) in a hybrid nanocomposite of films (∼100 μm thickness). Two polymorphs α- and β-PVF2 are co-stretched through the n-Ag crystallites in dendrites of hierarchical structures. A critical 0.5 wt% n-Ag dosage promotes this band of extinction coefficient to be enhanced by as much as 2.009 × 103, i.e. a 30% value in the Ag-surface plasmon band 350-650 nm (hν1). An electron donor Ag (4d105s1) bonds to an electron accepter moiety CF2 of PVF2, it tunes a dielectric field and sets up an up-energy conversion of the plasmon band. The FESEM and HRTEM images reveal fcc-Ag dendrites entangled with in-built PVF2 surface layers (2-3 nm thickness). The IR phonon bands show how a α → β-PVF2 transformation propagates onto a nascent n-Ag surface and how it is raised-up in small steps of 0.1 wt% and up to 5.0 wt%. In a model scheme, we illustrate how a rigid core-shell of a capsule conducts a new transfer mechanism of the energy to a cold surface plasmon (core) in a coherent collision, so as to balance a net value hν2 = h(ν3 - ν1). It absorbs light in a weak band at 210 nm (hν3) in a π → π* electron transition in the Cdbnd C bonds of the PVF2 (shell), and results in a negative absorption in a coherent excitation of the energy-carriers. A light-emitter on absorption over a wide range of wavelengths (200-650 nm) offers a unique type of energy-converter.

Generally applicable fed-batch culture concept based on the detection of metabolic state by on-line balancing.

PubMed

Jobé, Anna Marya; Herwig, Christoph; Surzyn, Martin; Walker, Bernhard; Marison, Ian; von Stockar, Urs

2003-06-20

In many microorganisms, flux limitations in oxidative metabolism lead to the formation of overflow metabolites even under fully aerobic conditions. This can be avoided if the specific growth rate is controlled at a low enough value. This is usually accomplished by controlling the substrate feeding profile in a fed-batch process. The present work proposes a control concept which is based on the on-line detection of metabolic state by on-line calculation of mass and elemental balances. The advantages of this method are: 1) the check of measurement consistency based on all of the available measurements, 2) the minimum requirement of a priori knowledge of metabolism, and 3) the exclusive use of simple and established on-line techniques which do not require direct measurement of the metabolite in question. The control concept has been linked to a simple adaptive controller and applied to fed-batch cultures of S. cerevisiae and E. coli, organisms which express different overflow metabolites, ethanol and acetic acid, respectively. Oxidative and oxidoreductive states of S. cerevisiae and E. coli cultures were detected with high precision. As demonstrated by the formation of acetic acid in E. coli cultures, metabolic states could be correctly distinguished for systems for which traditional methods, such as respiratory quotient (RQ), are insensitive. Hence, it could be shown that the control concept allowed avoidance of overflow metabolite formation and operation at maximum oxidative biomass productivity and oxidative conversion of substrate into biomass. Based on mass and elemental balances, the proposed method additionally provides a richness of additional information, such as yield coefficients and estimation of concentrations and specific conversion rates. These data certainly help the operator to additionally evaluate the state of the process on-line. Copyright 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 82: 627-639, 2003.

Dispersion of thermooptic coefficients of soda-lime-silica glasses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghosh, G.

1995-01-01

The thermooptic coefficients, i.e., the variation of refractive index with temperature (dn/dT), are analyzed in a physically meaningful model for two series of soda-lime-silica glasses. 25Na{sub 2}O{center_dot}xCaO{center_dot}(75 {minus} x)SiO{sub 2} and (25 {minus} x)Na{sub 2}O{center_dot}xCaO {center_dot} 75SiO{sub 2}. This model is based on three physical parameters--the thermal expansion coefficient and excitonic and isentropic optical bands that are in the vacuum ultraviolet region--instead of on consideration of the temperature coefficient of electronic polarizability, as suggested in 1960. This model is capable of predicting and analyzing the thermooptic coefficients throughout the transmission region of the optical glasses at any operating temperature.

Computational modeling and analysis of thermoelectric properties of nanoporous silicon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, H.; Yu, Y.; Li, G., E-mail: gli@clemson.edu

2014-03-28

In this paper, thermoelectric properties of nanoporous silicon are modeled and studied by using a computational approach. The computational approach combines a quantum non-equilibrium Green's function (NEGF) coupled with the Poisson equation for electrical transport analysis, a phonon Boltzmann transport equation (BTE) for phonon thermal transport analysis and the Wiedemann-Franz law for calculating the electronic thermal conductivity. By solving the NEGF/Poisson equations self-consistently using a finite difference method, the electrical conductivity σ and Seebeck coefficient S of the material are numerically computed. The BTE is solved by using a finite volume method to obtain the phonon thermal conductivity k{sub p}more » and the Wiedemann-Franz law is used to obtain the electronic thermal conductivity k{sub e}. The figure of merit of nanoporous silicon is calculated by ZT=S{sup 2}σT/(k{sub p}+k{sub e}). The effects of doping density, porosity, temperature, and nanopore size on thermoelectric properties of nanoporous silicon are investigated. It is confirmed that nanoporous silicon has significantly higher thermoelectric energy conversion efficiency than its nonporous counterpart. Specifically, this study shows that, with a n-type doping density of 10{sup 20} cm{sup –3}, a porosity of 36% and nanopore size of 3 nm × 3 nm, the figure of merit ZT can reach 0.32 at 600 K. The results also show that the degradation of electrical conductivity of nanoporous Si due to the inclusion of nanopores is compensated by the large reduction in the phonon thermal conductivity and increase of absolute value of the Seebeck coefficient, resulting in a significantly improved ZT.« less

CONSISTENCY AND THE FIFTH VIRIAL COEFFICIENT FOR A HARD-SPHERE GAS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cole, G.H.A.

1962-03-15

The modified superposition approximation g(/sup 3/)(r,s,t) = g(.syo 2)(r/ sup 2/g(/sup 2/)(s)g(/sup 2/)(t)STAl + X/sub 1/n + X/sub 2/n/sup 2/!(where g/sup (3)/si the triplet distribution, g(/sup 2/) the pair distribution, n the number density, and (r,s,t) are the particle separation distances) is used in conjunction with the Born-Green-Yvon equation of the classical theory of fluids in the calculation of the fifth virial coefficient E for a gas of hard spheres. The values of E derived directly from the virial theorem and alternatively from compressibility arguments are reconciled through a suitable choice of X/sub 2/. On the assumption X/sub i/ =more » constant it is found for hard spheres that X/sub 1/ = 0.1014b and X/sub 2/ = -0.0424b/sub 2/ (b = four times a molecular volume) ensures consistency as far as the fifth virial coefficient. The consistent value of E under this approximation is +0.0242b/sup 4/. The validity of the arguments is considered. (auth)« less

Progress status for the Mu2e calorimeter system

DOE PAGES

Pezzullo, Gianantonio; Budagov, J.; Carosi, R.; ...

2015-02-13

The Mu2e experiment at FNAL aims to measure the charged-lepton flavor violating neutrinoless conversion of a negative muon into an electron. The conversion results in a monochromatic electron with an energy slightly below the muon rest mass (104.97 MeV). The calorimeter should confirm that the candidates reconstructed by the extremely precise tracker system are indeed conversion electrons while performing a powerfulmore » $$\\mu/e$$ particle identification. Moreover, it should also provide a high level trigger for the experiment independently from the tracker system. The calorimeter should also be able to keep functionality in an environment where the background delivers a dose of ~ 10 krad/year in the hottest area and to work in the presence of 1 T axial magnetic field. These requirements translate in the design of a calorimeter with large acceptance, good energy resolution O(5%) and a reasonable position (time) resolution of ~<1 cm (<0.5ns). The baseline version of the calorimeter is composed by two disks of inner (outer) radius of 351 (660) mm filled by 1860 hexagonal $$BaF_2$$ crystals of 20 cm length. Each crystal is readout by two large area APD's. In this study, we summarize the experimental tests done so far as well as the simulation studies in the Mu2e environment.« less

Nutrients intake, performance and nitrogen balance of West African dwarf sheep fed graded levels of toasted Enterolobium cyclocarpum seeds as supplement to Panicum maximum.

PubMed

Idowu, O J; Arigbede, O M; Dele, P A; Olanite, J A; Adelusi, O O; Ojo, V O A; Sunmola, A S

2013-12-01

A study was conducted to assess the nutritive value of Enterolobium cyclocarpum seeds as supplementary feed for ruminant animals during the dry season when grasses are either not available or of low quality. Matured fruits of E. cyclocarpum were collected, toasted, peeled and then used for the trial. Thirty two West African Dwarf (WAD) sheep aged between 12 +/- 2 months with an average body weight of 10 +/- 2 kg were used in assessing the nutritive value of graded levels of toasted Enterolobium cyclocarpum seed in a concentrate diets as supplement to Panicum maximum basal diet. The percent compositions of the experimental diets were toasted E. cyclocarpum seeds at various levels of inclusion (0, 10, 20 and 30%) for diets 1, 2, 3 and 4. respectively. The diets (1-4) were consecutively fed to each animal at 50 g kg(-1) b.wt. for 12 weeks in a completely randomized design. Parameters taken were weekly body weights, daily feed intake, nutrient utilization and nitrogen balance status for each animal. Diet 2 had the highest significant (p < 0.05) nutrients intake being 871.88, 137.13, 147.59, 33.26 and 69.86 g day(-1) for DM, CP, CF, EE and ASH respectively. The Dry Matter Digestibility (DMD) coefficients decreased significantly (p < 0.05) with increased inclusion levels of toasted E. cyclocarpum seeds supplementation. Sheep fed diet 4 had the lowest feed conversion ratio (8.61) and the highest daily average gain of 58.93 g. However the animals fed Diet 2 had the highest nitrogen retension and converted their feed to flesh.

Derivation of Improved Surface and TOA Broadband Fluxes Using CERES-derived Narrowband-to-Broadband Coefficients

NASA Technical Reports Server (NTRS)

Khaiyer, Mandana M.; Doelling, David R.; Chan, Pui K.; Nordeen, MIchele L.; Palikonda, Rabindra; Yi, Yuhong; Minnis, Patrick

2006-01-01

Satellites can provide global coverage of a number of climatically important radiative parameters, including broadband (BB) shortwave (SW) and longwave (LW) fluxes at the top of the atmosphere (TOA) and surface. These parameters can be estimated from narrowband (NB) Geostationary Operational Environmental Satellite (GOES) data, but their accuracy is highly dependent on the validity of the narrowband-to-broadband (NB-BB) conversion formulas that are used to convert the NB fluxes to broadband values. The formula coefficients have historically been derived by regressing matched polarorbiting satellite BB fluxes or radiances with their NB counterparts from GOES (e.g., Minnis et al., 1984). More recently, the coefficients have been based on matched Earth Radiation Budget Experiment (ERBE) and GOES-6 data (Minnis and Smith, 1998). The Clouds and the Earth's Radiant Energy Budget (CERES see Wielicki et al. 1998)) project has recently developed much improved Angular Distribution Models (ADM; Loeb et al., 2003) and has higher resolution data compared to ERBE. A limited set of coefficients was also derived from matched GOES-8 and CERES data taken on Topical Rainfall Measuring Mission (TRMM) satellite (Chakrapani et al., 2003; Doelling et al., 2003). The NB-BB coefficients derived from CERES and the GOES suite should yield more accurate BB fluxes than from ERBE, but are limited spatially and seasonally. With CERES data taken from Terra and Aqua, it is now possible to derive more reliable NB-BB coefficients for any given area. Better TOA fluxes should translate to improved surface radiation fluxes derived using various algorithms. As part of an ongoing effort to provide accurate BB flux estimates for the Atmospheric Radiation Measurement (ARM) Program, this paper documents the derivation of new NB-BB coefficients for the ARM Southern Great Plains (SGP) domain and for the Darwin region of the Tropical Western Pacific (DTWP) domain.

Giant Peak Voltage of Thermopower Waves Driven by the Chemical Potential Gradient of Single-Crystalline Bi2 Te3.

PubMed

Singh, Swati; Mun, Hyeona; Lee, Sanghoon; Kim, Sung Wng; Baik, Seunghyun

2017-09-01

The self-propagating exothermic chemical reaction with transient thermovoltage, known as the thermopower wave, has received considerable attention recently. A greater peak voltage and specific power are still demanded, and materials with greater Seebeck coefficients have been previously investigated. However, this study employs an alternative mechanism of transient chemical potential gradient providing an unprecedentedly high peak voltage (maximum: 8 V; average: 2.3 V) and volume-specific power (maximum: 0.11 W mm -3 ; average: 0.04 W mm -3 ) using n-type single-crystalline Bi 2 Te 3 substrates. A mixture of nitrocellulose and sodium azide is used as a fuel, and ultraviolet photoelectron spectroscopy reveals a significant downshift in Fermi energy (≈5.09 eV) of the substrate by p-doping of the fuel. The induced electrical potential by thermopower waves has two distinct sources: the Seebeck effect and the transient chemical potential gradient. Surprisingly, the Seebeck effect contribution is less than 2.5% (≈201 mV) of the maximum peak voltage. The right combination of substrate, fuel doping, and anisotropic substrate geometry results in an order of magnitude greater transient chemical potential gradient (≈5.09 eV) upon rapid removal of fuel by exothermic chemical reaction propagation. The role of fuel doping and chemical potential gradient can be viewed as a key mechanism for enhanced heat to electric conversion performance. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Effect of Modality and Narration Style on Recall of Online Health Information: Results From a Web-Based Experiment

PubMed Central

van Weert, Julia CM; de Haes, Hanneke CJM; Loos, Eugene F; Smets, Ellen MA

2015-01-01

Background Older adults are increasingly using the Internet for health information; however, they are often not able to correctly recall Web-based information (eHealth information). Recall of information is crucial for optimal health outcomes, such as adequate disease management and adherence to medical regimes. Combining effective message strategies may help to improve recall of eHealth information among older adults. Presenting information in an audiovisual format using conversational narration style is expected to optimize recall of information compared to other combinations of modality and narration style. Objective The aim of this paper is to investigate the effect of modality and narration style on recall of health information, and whether there are differences between younger and older adults. Methods We conducted a Web-based experiment using a 2 (modality: written vs audiovisual information) by 2 (narration style: formal vs conversational style) between-subjects design (N=440). Age was assessed in the questionnaire and included as a factor: younger (<65 years) versus older (≥65 years) age. Participants were randomly assigned to one of four experimental webpages where information about lung cancer treatment was presented. A Web-based questionnaire assessed recall of eHealth information. Results Audiovisual modality (vs written modality) was found to increase recall of information in both younger and older adults (P=.04). Although conversational narration style (vs formal narration style) did not increase recall of information (P=.17), a synergistic effect between modality and narration style was revealed: combining audiovisual information with conversational style outperformed combining written information with formal style (P=.01), as well as written information with conversational style (P=.045). This finding suggests that conversational style especially increases recall of information when presented audiovisually. This combination of modality and narration style improved recall of information among both younger and older adults. Conclusions We conclude that combining audiovisual information with conversational style is the best way to present eHealth information to younger and older adults. Even though older adults did not proportionally recall more when audiovisual information was combined with conversational style than younger adults, this study reveals interesting implications for improving eHealth information that is effective for both younger and older adults. PMID:25910416

Model for the partition of neutral compounds between n-heptane and formamide.

PubMed

Karunasekara, Thushara; Poole, Colin F

2010-04-01

Partition coefficients for 84 varied compounds were determined for n-heptane-formamide biphasic partition system and used to derive a model for the distribution of neutral compounds between the n-heptane-rich and formamide-rich layers. The partition coefficients, log K(p), were correlated through the solvation parameter model giving log K(p)=0.083+0.559E-2.244S-3.250A-1.614B+2.387V with a multiple correlation coefficient of 0.996, standard error of the estimate 0.139, and Fisher statistic 1791. In the model, the solute descriptors are excess molar refraction, E, dipolarity/polarizability, S, overall hydrogen-bond acidity, A, overall hydrogen-bond basicity, B, and McGowan's characteristic volume, V. The model is expected to be able to estimate further values of the partition coefficient to about 0.13 log units for the same descriptor space covered by the calibration compounds (E=-0.26-2.29, S=0-1.93, A=0-1.25, B=0.02-1.58, and V=0.78-2.50). The n-heptane-formamide partition system is shown to have different selectivity to other totally organic biphasic systems and to be suitable for estimating descriptor values for compounds of low water solubility and/or stability.

Computations of Eisenstein series on Fuchsian groups

NASA Astrophysics Data System (ADS)

Avelin, Helen

2008-09-01

We present numerical investigations of the value distribution and distribution of Fourier coefficients of the Eisenstein series E(z;s) on arithmetic and non-arithmetic Fuchsian groups. Our numerics indicate a Gaussian limit value distribution for a real-valued rotation of E(z;s) as operatorname{Re} sD1/2 , operatorname{Im} sto infty and also, on non-arithmetic groups, a complex Gaussian limit distribution for E(z;s) when operatorname{Re} s>1/2 near 1/2 and operatorname{Im} sto infty , at least if we allow operatorname{Re} sto 1/2 at some rate. Furthermore, on non-arithmetic groups and for fixed s with operatorname{Re} s ge 1/2 near 1/2 , our numerics indicate a Gaussian limit distribution for the appropriately normalized Fourier coefficients.

Precise measurement of spin-averaged {chi}{sub cJ}(1P) mass using photon conversions in {psi}(2S){yields}{gamma}{chi}{sub cJ}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ablikim, M.; Bai, J.Z.; Bian, J.G.

2005-05-01

Using photon conversions to e{sup +}e{sup -} pairs, the energy spectrum of inclusive photons from {psi}(2S) radiative decays is measured with photon energy resolution ({sigma}{sub E{sub {gamma}}}) in the range from 2.3 to 3.8 MeV by BESII at the Beijing Electron-Positron Collider. The {chi}{sub cJ}(1P) states (J=0,1,2) are clearly observed, and their masses and the spin-averaged {chi}{sub cJ} mass are determined to be M{sub {chi}{sub c}{sub 0}}=3414.21{+-}0.39{+-}0.27, M{sub {chi}{sub c}{sub 1}}=3510.30{+-}0.14{+-}0.16, M{sub {chi}{sub c}{sub 2}}=3555.70{+-}0.59{+-}0.39, and M({sup 3}P{sub cog})=3524.85{+-}0.32{+-}0.30 MeV/c{sup 2}, respectively.

Simplifying the Reinsch algorithm for the Baker-Campbell-Hausdorff series

NASA Astrophysics Data System (ADS)

Van-Brunt, Alexander; Visser, Matt

2016-02-01

The Goldberg version of the Baker-Campbell-Hausdorff series computes the quantity Z ( X , Y ) = ln (" separators=" e X e Y ) = ∑ w g ( w ) w ( X , Y ) , where X and Y are not necessarily commuting in terms of "words" constructed from the {X, Y} "alphabet." The so-called Goldberg coefficients g(w) are the central topic of this article. This Baker-Campbell-Hausdorff series is a general purpose tool of very wide applicability in mathematical physics, quantum physics, and many other fields. The Reinsch algorithm for the truncated series permits one to calculate the Goldberg coefficients up to some fixed word length |w| by using nilpotent (|w| + 1) × (|w| + 1) matrices. We shall show how to further simplify the Reinsch algorithm, making its implementation (in principle) utterly straightforward using "off the shelf" symbolic manipulation software. Specific computations provide examples which help to provide a deeper understanding of the Goldberg coefficients and their properties. For instance, we shall establish some strict bounds (and some equalities) on the number of non-zero Goldberg coefficients. Unfortunately, we shall see that the number of nonzero Goldberg coefficients often grows very rapidly (in fact exponentially) with the word length |w|. Furthermore, the simplified Reinsch algorithm readily generalizes to many closely related but still quite distinct problems—we shall also present closely related results for the symmetric product S ( X , Y ) = ln (" separators=" e X / 2 e Y e X / 2 ) = ∑ w g S ( w ) w ( X , Y ) . Variations on such themes are straightforward. For instance, one can just as easily consider the "loop" product L ( X , Y ) = ln (" separators=" e X e Y e - X e - Y ) = ∑ w g L ( w ) w ( X , Y ) . This "loop" type of series is of interest, for instance, when considering either differential geometric parallel transport around a closed curve, non-Abelian versions of Stokes' theorem, or even Wigner rotation/Thomas precession in special relativity. Several other closely related series are also briefly investigated.

Influence of curing mode with a LED unit on polymerization contraction kinetics and degree of conversion of dental resin-based materials.

PubMed

Mortier, Eric; Simon, Yorick; Dahoun, Abdelsellam; Gerdolle, David

2009-01-01

The purpose of this study was to evaluate the influence of photopolymerization mode with a light emitting diode (LED) lamp on the curing contraction kinetics and degree of conversion of 3 resin-based restorative materials. The curing contraction kinetics of Admira (ADM), Filtek P60 (P60), and Filtek Flow (FLO) were measured by the glass slide method. The materials were exposed to light from a 1,000 mW/cm-(2) power LED lamp (Elipar Freelight 2) in 3 modes: 2 continuous modes of 20 and 40 seconds (C20 and C40), and 1 exponential mode (E20; 5 seconds of exponential power increase followed by 15 seconds of maximum intensity). The degree of conversion (DC) was measured for each of the materials, and each of the modes by Fourier transformed infra-red spectrometry. P60 had the significantly lowest final contraction and FLO the highest among all light exposure modes. The C20 and C40 modes did not produce any difference in contraction or degree of conversion. The E20 mode led to a significant slowing of contraction speed combined with greater final contraction. Use of a LED lamp (1,000 mW/cm2) in continuous mode reduces the exposure time by half for identical curing shrinkage and degree of conversion.

Enhanced converse magnetoelectric effect in cylindrical piezoelectric-magnetostrictive composites

NASA Astrophysics Data System (ADS)

Wu, Gaojian; Zhang, Ru; Zhang, Ning

2016-10-01

Enhanced converse magnetoelectric (ME) effect has been experimentally observed in cylindrical PZT-Terfenol-D piezoelectric-magnetostrictive bilayered composites, where the piezoelectric and magnetostrictive components are coupled through normal stresses instead of shear stresses that act in most of previous multiferroic composites. A theoretical model based on elastodynamics analysis has been proposed to describe the frequency response of converse ME effect for axial and radial modes in the bilayered cylindrical composites. The theory shows good agreement with the experimental results. The different variation tendency of resonant converse ME coefficient, as well as different variation rate of resonance frequency with bias magnetic field for axial and radial modes is interpreted in terms of demagnetizing effect. This work is of theoretical and technological significance for the application of converse ME effect as magnetic sensor, transducers, coil-free flux switch, etc.

Band structure modification of the thermoelectric Heusler-phase TiFe2Sn via Mn substitution.

PubMed

Zou, Tianhua; Jia, Tiantian; Xie, Wenjie; Zhang, Yongsheng; Widenmeyer, Marc; Xiao, Xingxing; Weidenkaff, Anke

2017-07-19

Doping (or substitution)-induced modification of the electronic structure to increase the electronic density of states (eDOS) near the Fermi level is considered as an effective strategy to enhance the Seebeck coefficient, and may consequently boost the thermoelectric performance. Through density-functional theory calculations of Mn-substituted TiFe 2-x Mn x Sn compounds, we demonstrate that the d-states of the substituted Mn atoms induce a strong resonant level near the Fermi energy. Our experimental results are in good agreement with the calculations. They show that Mn substitution results in a large increase of the Seebeck coefficient, arising from an enhanced eDOS in Heusler compounds. The results prove that a proper substitution position and element selection can increase the eDOS, leading to a higher Seebeck coefficient and thermoelectric performance of ecofriendly materials.

Enhanced photochemical conversion of NO2 to HONO on humic acids in the presence of benzophenone.

PubMed

Han, Chong; Yang, Wangjin; Yang, He; Xue, Xiangxin

2017-12-01

The photochemical conversion of NO 2 to HONO on humic acids (HA) in the presence of benzophenone (BP) was investigated using a flow tube reactor coupled to a NO x analyzer at ambient pressure. BP significantly enhanced the reduction of NO 2 to HONO on HA under simulated sunlight, as shown by the increase of NO 2 uptake coefficient (γ) and HONO yield with the mass ratio of BP to HA. The γ and HONO yield on the mixtures of HA and BP obviously depended on the environmental conditions. Both γ and HONO yield increased with the increase of irradiation intensity and temperature, whereas they decreased with pH. The γ exhibited a negative dependence on the NO 2 concentration, which had slight influences on the HONO yield. There were maximum values for the γ and HONO yield at relative humidity (RH) of 22%. Finally, atmospheric implications about the photochemical reaction of NO 2 and HA in the presence of photosensitive species were discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Estimating Optimal Transformations for Multiple Regression and Correlation.

DTIC Science & Technology

1982-07-01

algorithm; we minimize (2.4) e2 (,,, ...,) = E[e(Y) - 1I (X 2 j=l j 2holding EO =1, E6 = E0, =.-. =Ecp = 0, through a series of single function minimizations...X, x = INU = lIVe . Then (5.16) THEOREM. If 6*, p* is an optimal transformation for regression, then = ue*o Conversely, if e satisfies Xe = U6, Nll1...Stanford University, Tech. Report ORIONOO6. Gasser, T. and Rosenblatt, M. (eds.) (1979). Smoothing Techniques for Curve Estimation, in Lecture Notes in

The Mu2e experiment at Fermilab: Design and status

DOE PAGES

Donghia, R.

2017-12-18

The Mu2e experiment at Fermilab will search for coherent, neutrinoless conversion of negative muons into electrons in the field of an aluminum nucleus. The dynamics of such charged lepton flavour violating (CLFV) process is a twobody decay, resulting in a mono-energetic electron with an energy slightly below the muon rest mass. If no events are observed in three years of running, Mu2e will set an upper limit on the ratio between the conversion and the capture rates Rμe of ≤ 6 × 10 -17 (@90% C.L.). This will improve the current limit of four order of magnitudes with respect tomore » the previous best experiment. Mu2e complements and extends the current search for μ → eγ decay at MEG as well as the direct searches for new physics at the LHC. Indeed, such a CLFV process probes new physics at a scale inaccessible to direct searches at either present or planned high energy colliders. Observation of a signal will be a clear evidence for new physics beyond the Standard Model. To search for the muon conversion process, a very intense pulsed beam of negative muons (~ 10 10 μ/s) is stopped on an aluminum target inside a very long solenoid where the detector is also located. The Mu2e detector is composed of a straw tube tracker and an electromagnetic calorimeter consisting of arrays of CsI crystals. An external veto for cosmic rays is surrounding the detector solenoid. In 2016, Mu2e has passed the final approval stage from DOE and has started its construction phase. Data collection is planned for the end of 2021. Lastly, an overview of the physics motivations for Mu2e, the current status of the experiment and design of the muon beam-line and the detector is presented.« less

The Mu2e experiment at Fermilab: Design and status

DOE Office of Scientific and Technical Information (OSTI.GOV)

Donghia, R.

The Mu2e experiment at Fermilab will search for coherent, neutrinoless conversion of negative muons into electrons in the field of an aluminum nucleus. The dynamics of such charged lepton flavour violating (CLFV) process is a twobody decay, resulting in a mono-energetic electron with an energy slightly below the muon rest mass. If no events are observed in three years of running, Mu2e will set an upper limit on the ratio between the conversion and the capture rates Rμe of ≤ 6 × 10 -17 (@90% C.L.). This will improve the current limit of four order of magnitudes with respect tomore » the previous best experiment. Mu2e complements and extends the current search for μ → eγ decay at MEG as well as the direct searches for new physics at the LHC. Indeed, such a CLFV process probes new physics at a scale inaccessible to direct searches at either present or planned high energy colliders. Observation of a signal will be a clear evidence for new physics beyond the Standard Model. To search for the muon conversion process, a very intense pulsed beam of negative muons (~ 10 10 μ/s) is stopped on an aluminum target inside a very long solenoid where the detector is also located. The Mu2e detector is composed of a straw tube tracker and an electromagnetic calorimeter consisting of arrays of CsI crystals. An external veto for cosmic rays is surrounding the detector solenoid. In 2016, Mu2e has passed the final approval stage from DOE and has started its construction phase. Data collection is planned for the end of 2021. Lastly, an overview of the physics motivations for Mu2e, the current status of the experiment and design of the muon beam-line and the detector is presented.« less

Experimental evaluation of Langmuir probe sheath potential coefficient on the HL-2A tokamak

NASA Astrophysics Data System (ADS)

Nie, L.; Xu, M.; Ke, R.; Yuan, B. D.; Wu, Y. F.; Cheng, J.; Lan, T.; Yu, Y.; Hong, R. J.; Guo, D.; Ting, L.; Dong, Y. B.; Zhang, Y. P.; Song, X. M.; Zhong, W. L.; Wang, Z. H.; Sun, A. P.; Xu, J. Q.; Chen, W.; Yan, L. W.; Zou, X. L.; Duan, X. R.; HL-2A Team

2018-03-01

Systematic calibration experiment of Langmuir probe sheath potential coefficient Λ, which is a critical coefficient for estimating plasma sheath potential, has been carried out in the HL-2A tokamak deuterium plasmas. The electron energy probability function (EEPF) shows that electron outside last-closed-flux-surface (LCFS) is Maxwell distribution, but inside LCFS it changes to bi-Maxwell. Two kinds of plasma potential measuring method and three kinds Λ estmating method were compared. It is found that the estimated Λ coefficient is in the region of 2-3 outside LCFS and then increases to ~5 inside LCFS due to the high temperature electron effect. Fortunately, the results show that the commonly used value Λ  =  2.8 is still available to calculate plasma potential when we use the overestimated electron temperature measured by three-tip probe in bi-Maxwell case. Further analysis indicated this value should be corrected. Or it may lead to a error when we calculate the the electric field {{E}r} and its shear d{{E}r}/dr . The corrected value monotonically increased from ~2.2 to ~2.9 while Langmuir probe moved from 40 mm outside LCFS to 20 mm inside LCFS.

Mu2e: a Muon to Electron Conversion Experiment at Fermilab

NASA Astrophysics Data System (ADS)

Brown, David

2014-03-01

We present the status of Mu2e, a proposed experiment to measure the rate of muon to electron conversion in the field of a nucleus. The Mu2e experiment will be hosted by Fermilab at a new muon campus, using a new beamline to deliver protons to the muon generation target. Mu2e will use a series of three solenoids to collect, transport, stop, and analyze the muons produced when the 8 GeV pulsed proton beam from the booster hits the tungsten production target. The 200 nsec wide proton pulse is designed to have a ratio of out-of-time to in-time protons better than 10-10, insuring a measurement time window of approximately 1 microsecond essentially free from beam pion background. A precision, low-mass straw tube tracker will measure electron momenta with a precision of 1/1000, allowing clean separation of the conversion signal from Decay In Orbit electrons, the principle experimental background. Extensive coverage of multi-layer scintillation counters will detect 99.99% of the cosmic muons which could generate fake signals. A crystal calorimeter will provide particle ID to further reduce backgrounds. Detailed simulations show a 3-year run with 7.56×1017 stopped muons will allow a Single Event Sensitivity of 2×10-17, allowing an estimated 90% confidence level sensitivity to R of 6×10-17, a four-orders of magnitude improvement over existing limits. The Mu2e schedule is technically limited, with commissioning beginning in 2019. Mu2e may also run at Project X with 10× higher luminosity using either an aluminum or titanium target after minimal upgrades.

CFD Modeling of the Multipurpose Hydrogen Test Bed (MHTB) Self-Pressurization and Spray Bar Mixing Experiments in Normal Gravity: Effect of the Accommodation Coefficient on the Tank Pressure

NASA Technical Reports Server (NTRS)

Kartuzova, Olga; Kassemi, Mohammad

2015-01-01

A CFD model for simulating the self-pressurization of a large scale liquid hydrogen storage tank is utilized in this paper to model the MHTB self-pressurization experiment. The kinetics-based Schrage equation is used to account for the evaporative and condensi ng interfacial mass flows in this model. The effect of the accommodation coefficient for calculating the interfacial mass transfer rate on the tank pressure during tank selfpressurization is studied. The values of the accommodation coefficient which were considered in this study vary from 1.0e-3 to 1.0e-1 for the explicit VOF model and from 1.0e-4 to 1.0e-3 for the implicit VOF model. The ullage pressure evolutions are compared against experimental data. A CFD model for controlling pressure in cryogenic storage tanks by spraying cold liquid into the ullage is also presented. The Euler-Lagrange approach is utilized for tracking the spray droplets and for modeling the interaction between the droplets and the continuous phase (ullage). The spray model is coupled with the VOF model by performing particle tracking in the ullage, removing particles from the ullage when they reach the interface, and then adding their contributions to the liquid. Droplet-ullage heat and mass transfer are modeled. The flow, temperature, and interfacial mass flux, as well as droplets trajectories, size distribution and temperatures predicted by the model are presented. The ul lage pressure and vapor temperature evolutions are compared with experimental data obtained from the MHTB spray bar mixing experiment. The effect of the accommodation coefficient for calculating the interfacial and droplet mass transfer rates on the tank pressure during mixing of the vapor using spray is studied. The values used for the accommodation coefficient at the interface vary from 1.0e-5 to 1.0e-2. The droplet accommodation coefficient values vary from 2.0e-6 to 1.0e-4.

Physicochemical application of capillary chromatography

NASA Astrophysics Data System (ADS)

Vasil'ev, A. V.; Aleksandrov, E. N.

1992-04-01

The application of capillary gas chromatography in the determination of the free energy, enthalpy, and entropy of sorption, the saturated vapour pressure and activity coefficients, the assessment of the lipophilicity of volatile compounds, and the study of the properties of polymers and liquid crystals is described. The use of reaction cappillary chromatography in kinetic studies of conformational conversions, thermal degradation, and photochemical reactions is examined. Studies on the use of capillary columns for determination of the second virial coefficients and viscosity of gases and the diffusion coefficients in gases, liquids, supercritical fluids, and polymers are analysed. The bibliography includes 114 references.

Assessing the impact of minimizing arginine conversion in fully defined SILAC culture medium in human embryonic stem cells.

PubMed

Scheerlinck, Ellen; Van Steendam, Katleen; Daled, Simon; Govaert, Elisabeth; Vossaert, Liesbeth; Meert, Paulien; Van Nieuwerburgh, Filip; Van Soom, Ann; Peelman, Luc; De Sutter, Petra; Heindryckx, Björn; Dhaenens, Maarten; Deforce, Dieter

2016-10-01

We present a fully defined culture system (adapted Essential8 TM [E8 TM ] medium in combination with vitronectin) for human embryonic stem cells that can be used for SILAC purposes. Although a complete incorporation of the labels was observed after 4 days in culture, over 90% of precursors showed at least 10% conversion. To reduce this arginine conversion, E8 TM medium was modified by adding (1) l-proline, (2) l-ornithine, (3) N ω -hydroxy-nor-l-arginine acetate, or by (4) lowering the arginine concentration. Reduction of arginine conversion was best obtained by adding 5 mM l-ornithine, followed by 3.5 mM l-proline and by lowering the arginine concentration in the medium to 99.5 μM. No major changes in pluripotency and cell amount could be observed for the adapted E8 TM media with ornithine and proline. However, our subsequent ion mobility assisted data-independent acquisition (high-definition MS) proteome analysis cautions for ongoing changes in the proteome when aiming at longer term suppression of arginine conversion. © 2016 The Authors. Proteomics Published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Stable dye-sensitized solar cells based on a gel electrolyte with ethyl cellulose as the gelator

NASA Astrophysics Data System (ADS)

Vasei, Maryam; Tajabadi, Fariba; Jabbari, Ali; Taghavinia, Nima

2015-09-01

A simple gelating process is developed for the conventional acetonitrile-based electrolyte of dye solar cells, based on ethyl cellulose as the gelator. The electrolyte becomes quasi-solid-state upon addition of an ethanolic solution of ethyl cellulose to the conventional acetonitrile-based liquid electrolyte. The photovoltaic conversion efficiency with the new gel electrolyte is only slightly lower than with the liquid electrolyte, e.g., 6.5 % for liquid electrolyte versus 5.9 % for gel electrolyte with 5.8 wt% added ethyl cellulose. Electrolyte gelation has small effect on the ionic diffusion coefficient of iodide, and the devices are remarkably stable for at least 550 h under irradiation at 55 °C.

Heterogeneous integration of lithium niobate and silicon nitride waveguides for wafer-scale photonic integrated circuits on silicon.

PubMed

Chang, Lin; Pfeiffer, Martin H P; Volet, Nicolas; Zervas, Michael; Peters, Jon D; Manganelli, Costanza L; Stanton, Eric J; Li, Yifei; Kippenberg, Tobias J; Bowers, John E

2017-02-15

An ideal photonic integrated circuit for nonlinear photonic applications requires high optical nonlinearities and low loss. This work demonstrates a heterogeneous platform by bonding lithium niobate (LN) thin films onto a silicon nitride (Si₃N₄) waveguide layer on silicon. It not only provides large second- and third-order nonlinear coefficients, but also shows low propagation loss in both the Si₃N₄ and the LN-Si₃N₄ waveguides. The tapers enable low-loss-mode transitions between these two waveguides. This platform is essential for various on-chip applications, e.g., modulators, frequency conversions, and quantum communications.

On the minimum electron transport coefficients in tokamaks in the range of low collision frequencies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Merezhkin, V. G.

2009-06-15

There are two close empirical scalings, namely, the T-11 and neo-Alcator ones, that provide correct estimates for the energy confinement time in tokamaks in ohmic heating regimes in the linear part of the dependence {tau}{sub E}(n-bar{sub e}) in the range of low values of n-bar{sub e} and <{nu}{sub e}{sup *}> {<=} 1. The similar character of electron energy confinement in this range, which expands with increasing magnetic field B{sub 0}, has stimulated the search for dimensionless parameters and simple physical models that would explain the experimentally observed dependences {chi}{sub e} {approx} 1/n{sub e} and {tau}{sub Ee} {approx} n-bar{sub e}. Inmore » 1987, T. Okhawa showed that the experimental data were satisfactorily described by the formula {chi}{sub eperpendicular} = (c{sup 2}/{omega}{sub pe}{sup 2}){nu}{sub e}/qR, in deriving of which the random spatial leap along the radius r on the electron trajectory was assumed to be the same as that in the coefficient of the poloidal field diffusion, while the repetition rate of these leaps was assumed to be {nu}{sub e}/qR. In 2004, J. Callen took into account the decrease in the fraction of transient electrons with increasing toroidal ratio {epsilon} = r/R and corrected the coefficient c{sup 2}/{omega}{sub pe}{sup 2} in Okhawa equation by the factor {sigma}{sub ||} {sup Sp}/{sigma}{sub ||}{sup neo}. If one takes into account this correction and assumes that the frequency of the stochastic process is equal to the reciprocal of the half-period of rotation of a trapped electron along its banana trajectory, then the resulting expression for {chi}{sub eperpendicular} will coincide with the T-11 scaling: {chi}{sub e}{sup an} {infinity} {epsilon}{sup 1.75}(T{sub e}/A{sub i}){sup 0.5}/(n{sub e}qR) at Ai = 1. If the same stochastic process also involves ions, it may result in the opening of the orbit of a trapped ion at the distance {approx}(c/{omega}{sub pe})(m{sub i}/m{sub e}){sup 1/4}. In this case, the calculated coefficient of electron and ion diffusion D is close to D{sup an} {approx} {chi}{sub e}{sup an}/2.« less

5 CFR 531.221 - Maximum payable rate rule.

Code of Federal Regulations, 2010 CFR

2010-01-01

... before the reassignment. (ii) If the rate resulting from the geographic conversion under paragraph (c)(2... previous rate (i.e., the former special rate after the geographic conversion) with the rates on the current... 5 Administrative Personnel 1 2010-01-01 2010-01-01 false Maximum payable rate rule. 531.221...

Applications of 2D to 3D conversion for educational purposes

NASA Astrophysics Data System (ADS)

Koido, Yoshihisa; Morikawa, Hiroyuki; Shiraishi, Saki; Takeuchi, Soya; Maruyama, Wataru; Nakagori, Toshio; Hirakata, Masataka; Shinkai, Hirohisa; Kawai, Takashi

2013-03-01

There are three main approaches creating stereoscopic S3D content: stereo filming using two cameras, stereo rendering of 3D computer graphics, and 2D to S3D conversion by adding binocular information to 2D material images. Although manual "off-line" conversion can control the amount of parallax flexibly, 2D material images are converted according to monocular information in most cases, and the flexibility of 2D to S3D conversion has not been exploited. If the depth is expressed flexibly, comprehensions and interests from converted S3D contents are anticipated to be differed from those from 2D. Therefore, in this study we created new S3D content for education by applying 2D to S3D conversion. For surgical education, we created S3D surgical operation content under a surgeon using a partial 2D to S3D conversion technique which was expected to concentrate viewers' attention on significant areas. And for art education, we converted Ukiyoe prints; traditional Japanese artworks made from a woodcut. The conversion of this content, which has little depth information, into S3D, is expected to produce different cognitive processes from those evoked by 2D content, e.g., the excitation of interest, and the understanding of spatial information. In addition, the effects of the representation of these contents were investigated.

Conversion coefficients from fluence to effective dose for heavy ions with energies up to 3 GeV/A.

PubMed

Sato, T; Tsuda, S; Sakamoto, Y; Yamaguchi, Y; Niita, K

2003-01-01

Radiological protection against high-energy heavy ions has been an essential issue in the planning of long-term space missions. The fluence to effective dose conversion coefficients have been calculated for heavy ions using the particle and heavy ion transport code system PHITS coupled with an anthropomorphic phantom of the MIRD5 type. The calculations were performed for incidences of protons and typical space heavy ions--deuterons, tritons, 3He, alpha particles, 12C, 20Ne, 40Ar, 40Ca and 56Fe--with energies up to 3 GeV/A in the isotropic and anterior-posterior irradiation geometries. A simple fitting formula that can predict the effective dose from almost all kinds of space heavy ions below 3 GeV/A within an accuracy of 30% is deduced from the results.

Online and Offline Conversations About Alcohol: Comparing the Effects of Familiar and Unfamiliar Discussion Partners.

PubMed

Hendriks, Hanneke; de Bruijn, Gert-Jan; Meehan, Orla; van den Putte, Bas

2016-07-01

Although research has demonstrated that interpersonal communication about alcohol influences drinking behaviors, this notion has mainly been examined in offline contexts with familiar conversation partners. The present study investigated how communication mode and familiarity influence conversational valence (i.e., how negatively or positively people talk) and binge drinking norms. During a 2 (offline vs. online communication) × 2 (unfamiliar vs. familiar conversation partner) lab experiment, participants (N = 76) were exposed to an anti-binge drinking campaign, after which they discussed binge drinking and the campaign. Binge drinking norms were measured 1 week before and directly after the discussion. Results revealed that conversations between unfamiliar conversation partners were positive about the campaign, especially in offline settings, subsequently leading to healthier binge drinking norms. We recommend that researchers further investigate the influence of communication mode and familiarity on discussion effects, and we suggest that health promotion attempts might benefit from eliciting conversations about anti-binge drinking campaigns between unfamiliar persons.

Dose conversion coefficients for electron exposure of the human eye lens: calculations including a whole body phantom.

PubMed

Behrens, R

2013-07-01

In this work, conversion coefficients from electron fluence to absorbed dose to the eye lens were calculated using Monte Carlo simulations based on a detailed stylised eye model and a very simple but whole body phantom. These data supersede and complement data published earlier based on the simulation of only a single stylised eye. The new data differ from the old ones by not more than 3, 4, 7 and 16 % for angles of radiation incidence of α=0°, 15°, 30° and 45°, respectively, due to the inclusion of the whole body phantom. The data presented in the present work also complement those of a recent report of the International Commission on Radiological Protection (ICRP) (ICRP Publication 116), where conversion coefficients from electron fluence to absorbed dose to the lens of the eye are shown for solely 0°, 180° and isotropic radiation incidence (but for a much broader range of energies). In this article, values are provided for angles of incidence of 0° up to 180° in steps of 15° and for rotational geometry; no systematic deviation was observed from the values given in ICRP Publication 116 for 0° (based on the application of a bare eye) and 180° (based on the application of a voxel whole body phantom). Data are given for monoenergetic electrons from 0.1 up to 10 MeV and for a broad parallel beam geometry in vacuum.

Boron diffusion in bcc-Fe studied by first-principles calculations

NASA Astrophysics Data System (ADS)

Xianglong, Li; Ping, Wu; Ruijie, Yang; Dan, Yan; Sen, Chen; Shiping, Zhang; Ning, Chen

2016-03-01

The diffusion mechanism of boron in bcc-Fe has been studied by first-principles calculations. The diffusion coefficients of the interstitial mechanism, the B-monovacancy complex mechanism, and the B-divacancy complex mechanism have been calculated. The calculated diffusion coefficient of the interstitial mechanism is D0 = 1.05 × 10-7 exp (-0.75 eV/kT) m2 · s-1, while the diffusion coefficients of the B-monovacancy and the B-divacancy complex mechanisms are D1 = 1.22 × 10-6 f1 exp (-2.27 eV/kT) m2 · s-1 and D2 ≈ 8.36 × 10-6 exp (-4.81 eV/kT) m2 · s-1, respectively. The results indicate that the dominant diffusion mechanism in bcc-Fe is the interstitial mechanism through an octahedral interstitial site instead of the complex mechanism. The calculated diffusion coefficient is in accordance with the reported experiment results measured in Fe-3%Si-B alloy (bcc structure). Since the non-equilibrium segregation of boron is based on the diffusion of the complexes as suggested by the theory, our calculation reasonably explains why the non-equilibrium segregation of boron is not observed in bcc-Fe in experiments. Project supported by the National Natural Science Foundation of China (Grant No. 51276016) and the National Basic Research Program of China (Grant No. 2012CB720406).

Flowfield Measurements in the Vortex Wake of a Missile at High Angle of Attack in Turbulence

DTIC Science & Technology

1988-12-01

pressure coefficient Cy: side force coefficient d: base diameter of the missile body F: blockage correction K: wind tunnel calibration factor LI : missile...and assistance in the wind tunnel apparatus and data acquisition s -;te1 m. I would like to thank Lt. Ao Chia-Ning. Republic of China Navy, Mr. Li ...axisymmetric missile configuration. 6- MO GRID + WIJS RE 1.33 E+05 z 2- Li 0- O C8 -C0 tq *tt~E I ’mtO0 E 5 , • r;.H/ 2 011USE 6 -6 x J! ’ 5SE 3 ,AHOSE

Giant magnetoelectric effects achieved by tuning spin cone symmetry in Y-type hexaferrites

DOE PAGES

Zhai, Kun; Wu, Yan; Shen, Shipeng; ...

2017-09-12

Multiferroics materials, which exhibit coupled magnetic and ferroelectric properties, have attracted tremendous research interest because of their potential in constructing next-generation multifunctional devices. The application of single-phase multiferroics is currently limited by their usually small magnetoelectric effects. Here, we report the realization of giant magnetoelectric effects in a Y-type hexaferrite Ba 0.4Sr 1.6Mg 2Fe 12O 22 single crystal, which exhibits record-breaking direct and converse magnetoelectric coefficients and a large electric-field-reversed magnetization. We have uncovered the origin of the giant magnetoelectric effects by a systematic study in the Ba 2-x Sr x Mg 2Fe 12O 22 family with magnetization, ferroelectricity andmore » neutron diffraction measurements. With the transverse spin cone symmetry restricted to be two-fold, the one-step sharp magnetization reversal is realized and giant magnetoelectric coefficients are achieved. Our study reveals that tuning magnetic symmetry is an effective route to enhance the magnetoelectric effects also in multiferroic hexaferrites.« less

Exploring Charge Transport in Guest Molecule Infiltrated Cu 3(BTC) 2 Metal Organic Framework

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leonard, Francois Leonard; Stavila, Vitalie; Allendorf, Mark D.

2014-09-01

The goal of this Exploratory Express project was to expand the understanding of the physical properties of our recently discovered class of materials consisting of metal-organic frameworks with electroactive ‘guest’ molecules that together form an electrically conducting charge-transfer complex (molecule@MOF). Thin films of Cu 3(BTC) 2 were grown on fused silica using solution step-by-step growth and were infiltrated with the molecule tetracyanoquinodimethane (TCNQ). The infiltrated MOF films were extensively characterized using optical microscopy, scanning electron microscopy, Raman spectroscopy, electrical conductivity, and thermoelectric properties. Thermopower measurements on TCNQ@Cu 3(BTC) 2 revealed a positive Seebeck coefficient of ~400 μV/k, indicating that holesmore » are the primary carriers in this material. The high value of the Seebeck coefficient and the expected low thermal conductivity suggest that molecule@MOF materials may be attractive for thermoelectric power conversion applications requiring low cost, solution-processable, and non-toxic active materials.« less

Giant magnetoelectric effects achieved by tuning spin cone symmetry in Y-type hexaferrites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhai, Kun; Wu, Yan; Shen, Shipeng

Multiferroics materials, which exhibit coupled magnetic and ferroelectric properties, have attracted tremendous research interest because of their potential in constructing next-generation multifunctional devices. The application of single-phase multiferroics is currently limited by their usually small magnetoelectric effects. Here, we report the realization of giant magnetoelectric effects in a Y-type hexaferrite Ba 0.4Sr 1.6Mg 2Fe 12O 22 single crystal, which exhibits record-breaking direct and converse magnetoelectric coefficients and a large electric-field-reversed magnetization. We have uncovered the origin of the giant magnetoelectric effects by a systematic study in the Ba 2-x Sr x Mg 2Fe 12O 22 family with magnetization, ferroelectricity andmore » neutron diffraction measurements. With the transverse spin cone symmetry restricted to be two-fold, the one-step sharp magnetization reversal is realized and giant magnetoelectric coefficients are achieved. Our study reveals that tuning magnetic symmetry is an effective route to enhance the magnetoelectric effects also in multiferroic hexaferrites.« less

The effect of temperature and loading frequency on the converse piezoelectric response of soft PZT ceramics

NASA Astrophysics Data System (ADS)

Dapeng, Zhu; Qinghui, Jiang; Yingwei, Li

2017-12-01

The converse piezoelectric coefficient d 33 of soft PZT ceramics was measured from 20 °C to 150 °C under different loading frequency. Results showed that in the tested temperature range, the evolution of d 33 obeys the Rayleigh-law behavior. The influence of temperature on d 33 is a little complicated. For instance, the maximum d 33 was observed at 150 °C when the applied electric field E was at 0.1 kV mm-1. When E increased to 0.3 kV mm-1 and 0.4 kV mm-1, the maximum d 33 was observed at 120 °C and 100 °C, respectively. Such behaviors are rationalized by the evolution of the Rayleigh parameters d init and α. For d init, it increases as temperature increases. While for α, it first increases and then decreases with the increase of temperature due to the evolution of the spontaneous strain and the volume of the switched domains. In the tested loading frequency, d 33 decreased linearly with the logarithm of the frequency of electric field. With the increase of temperature, the influence of frequency on d 33 gradually weakened, implying that at high temperature, the motion of domain walls became active and the pinning effect of defects nearly disappeared.

Cosensitized Quantum Dot Solar Cells with Conversion Efficiency over 12.

PubMed

Wang, Wei; Feng, Wenliang; Du, Jun; Xue, Weinan; Zhang, Linlin; Zhao, Leilei; Li, Yan; Zhong, Xinhua

2018-03-01

The improvement of sunlight utilization is a fundamental approach for the construction of high-efficiency quantum-dot-based solar cells (QDSCs). To boost light harvesting, cosensitized photoanodes are fabricated in this work by a sequential deposition of presynthesized Zn-Cu-In-Se (ZCISe) and CdSe quantum dots (QDs) on mesoporous TiO 2 films via the control of the interactions between QDs and TiO 2 films using 3-mercaptopropionic acid bifunctional linkers. By the synergistic effect of ZCISe-alloyed QDs with a wide light absorption range and CdSe QDs with a high extinction coefficient, the incident photon-to-electron conversion efficiency is significantly improved over single QD-based QDSCs. It is found that the performance of cosensitized photoanodes can be optimized by adjusting the size of CdSe QDs introduced. In combination with titanium mesh supported mesoporous carbon as a counterelectrode and a modified polysulfide solution as an electrolyte, a champion power conversion efficiency up to 12.75% (V oc = 0.752 V, J sc = 27.39 mA cm -2 , FF = 0.619) is achieved, which is, as far as it is known, the highest efficiency for liquid-junction QD-based solar cells reported. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An alternative to the breeder's and Lande's equations.

PubMed

Houchmandzadeh, Bahram

2014-01-10

The breeder's equation is a cornerstone of quantitative genetics, widely used in evolutionary modeling. Noting the mean phenotype in parental, selected parents, and the progeny by E(Z0), E(ZW), and E(Z1), this equation relates response to selection R = E(Z1) - E(Z0) to the selection differential S = E(ZW) - E(Z0) through a simple proportionality relation R = h(2)S, where the heritability coefficient h(2) is a simple function of genotype and environment factors variance. The validity of this relation relies strongly on the normal (Gaussian) distribution of the parent genotype, which is an unobservable quantity and cannot be ascertained. In contrast, we show here that if the fitness (or selection) function is Gaussian with mean μ, an alternative, exact linear equation of the form R' = j(2)S' can be derived, regardless of the parental genotype distribution. Here R' = E(Z1) - μ and S' = E(ZW) - μ stand for the mean phenotypic lag with respect to the mean of the fitness function in the offspring and selected populations. The proportionality coefficient j(2) is a simple function of selection function and environment factors variance, but does not contain the genotype variance. To demonstrate this, we derive the exact functional relation between the mean phenotype in the selected and the offspring population and deduce all cases that lead to a linear relation between them. These results generalize naturally to the concept of G matrix and the multivariate Lande's equation Δ(z) = GP(-1)S. The linearity coefficient of the alternative equation are not changed by Gaussian selection.

Structure of sup 118 Sb nucleus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gulyas, J.; Fenyes, T.; Fayez, M.

1992-10-01

{gamma}, {gamma}{gamma}-coincidence, internal conversion electron, and {gamma}-ray angular distribution spectra of the {sup 118}Sn({ital p},{ital n}{gamma}){sup 118}Sb reaction were measured at different bombarding proton energies between 5.5 and 7.5 MeV. {gamma}, {gamma}{gamma}-coincidence, and internal conversion electron spectra of the {sup 115}In ({alpha},{ital n}{gamma}){sup 118}Sb reaction were also measured at {ital E}{sub {alpha}}=14.5 MeV. Ge(HP), Ge(Li), Ge(LEPS) {gamma}-ray detectors, as well as a superconducting magnetic lens electron spectrometer (with Si(Li) detectors), were used in the experiments. About 210 (including {similar to}130 new) {gamma} rays have been assigned to {sup 118}Sb. The deduced {sup 118}Sb level scheme contains more than 70 newmore » levels. On the basis of the internal conversion coefficients, Hauser-Feshbach analysis of ({ital p},{ital n}) reaction cross sections, {gamma}-ray angular distributions, and other arguments spin and parity values have been determined. The parabolic rule'' prediction of the energy splitting of different proton-neutron multiplets enabled the identification of many proton-neutron multiplet states. The energy spectrum and electromagnetic properties have been calculated in the framework of the interacting boson-fermion-fermion--odd-odd truncated quadrupole phonon model, and reasonably good agreement has been obtained between experimental and theoretical results.« less

Liver conversion of docosahexaenoic and arachidonic acids from their 18-carbon precursors in rats on a DHA-free but α-LNA-containing n-3 PUFA adequate diet.

PubMed

Gao, Fei; Kim, Hyung-Wook; Igarashi, Miki; Kiesewetter, Dale; Chang, Lisa; Ma, Kaizong; Rapoport, Stanley I

2011-01-01

The long-chain polyunsaturated fatty acids (PUFAs), eicosapentaenoic acid (EPA, 20:5n-3), docosahexaenoic acid (DHA, 22:6n-3), and arachidonic acid (AA, 20:4n-6), are critical for health. These PUFAs can be synthesized in liver from their plant-derived precursors, α-linolenic acid (α-LNA, 18:3n-3) and linoleic acid (LA, 18:2n-6). Vegetarians and vegans may have suboptimal long-chain n-3 PUFA status, and the extent of the conversion of α-LNA to EPA and DHA by the liver is debatable. We quantified liver conversion of DHA and other n-3 PUFAs from α-LNA in rats fed a DHA-free but α-LNA (n-3 PUFA) adequate diet, and compared results to conversion of LA to AA. [U-(13)C]LA or [U-(13)C]α-LNA was infused intravenously for 2h at a constant rate into unanesthetized rats fed a DHA-free α-LNA adequate diet, and published equations were used to calculate kinetic parameters. The conversion coefficient k(⁎) of DHA from α-LNA was much higher than for AA from LA (97.2×10(-3) vs. 10.6×10(-3)min(-1)), suggesting that liver elongation-desaturation is more selective for n-3 PUFA biosynthesis on a per molecule basis. The net daily secretion rate of DHA, 20.3μmol/day, exceeded the reported brain DHA consumption rate by 50-fold, suggesting that the liver can maintain brain DHA metabolism with an adequate dietary supply solely of α-LNA. This infusion method could be used in vegetarians or vegans to determine minimal daily requirements of EPA and DHA in humans. Published by Elsevier B.V.

Inverted thermal conversion - GaAs, a new alternative material for integrated circuits

NASA Technical Reports Server (NTRS)

Lagowski, J.; Gatos, H. C.; Kang, C. H.; Skowronski, M.; Ko, K. Y.

1986-01-01

A new type of GaAs is developed which exhibits inverted thermal conversion (ITC); i.e., it converts from conducting to semiinsulating upon annealing at about 850 C. In device fabrication, its low resistivity prior to high-temperature processing differentiates ITC GaAs from the standard semiinsulating GaAs. The ITC characteristics are obtained through control of the concentration of the midgap donor EL2 based on heat treatment and crystal-growth modification. Thus EL2 does not exist in the conducting state of ITC GaAs. Conversion to the semiinsulating state during 850 C annealing is caused by the formation of EL2.

Electron Jet Detected by MMS at Dipolarization Front

NASA Astrophysics Data System (ADS)

Liu, C. M.; Fu, H. S.; Vaivads, A.; Khotyaintsev, Y. V.; Gershman, D. J.; Hwang, K.-J.; Chen, Z. Z.; Cao, D.; Xu, Y.; Yang, J.; Peng, F. Z.; Huang, S. Y.; Burch, J. L.; Giles, B. L.; Ergun, R. E.; Russell, C. T.; Lindqvist, P.-A.; Le Contel, O.

2018-01-01

Using MMS high-resolution measurements, we present the first observation of fast electron jet (Ve 2,000 km/s) at a dipolarization front (DF) in the magnetotail plasma sheet. This jet, with scale comparable to the DF thickness ( 0.9 di), is primarily in the tangential plane to the DF current sheet and mainly undergoes the E × B drift motion; it contributes significantly to the current system at the DF, including a localized ring-current that can modify the DF topology. Associated with this fast jet, we observed a persistent normal electric field, strong lower hybrid drift waves, and strong energy conversion at the DF. Such strong energy conversion is primarily attributed to the electron-jet-driven current (E ṡ je ≈ 2 E ṡ ji), rather than the ion current suggested in previous studies.

Electron Transport Coefficients and Effective Ionization Coefficients in SF6-O2 and SF6-Air Mixtures Using Boltzmann Analysis

NASA Astrophysics Data System (ADS)

Wei, Linsheng; Xu, Min; Yuan, Dingkun; Zhang, Yafang; Hu, Zhaoji; Tan, Zhihong

2014-10-01

The electron drift velocity, electron energy distribution function (EEDF), density-normalized effective ionization coefficient and density-normalized longitudinal diffusion velocity are calculated in SF6-O2 and SF6-Air mixtures. The experimental results from a pulsed Townsend discharge are plotted for comparison with the numerical results. The reduced field strength varies from 40 Td to 500 Td (1 Townsend=10-17 V·cm2) and the SF6 concentration ranges from 10% to 100%. A Boltzmann equation associated with the two-term spherical harmonic expansion approximation is utilized to gain the swarm parameters in steady-state Townsend. Results show that the accuracy of the Boltzmann solution with a two-term expansion in calculating the electron drift velocity, electron energy distribution function, and density-normalized effective ionization coefficient is acceptable. The effective ionization coefficient presents a distinct relationship with the SF6 content in the mixtures. Moreover, the E/Ncr values in SF6-Air mixtures are higher than those in SF6-O2 mixtures and the calculated value E/Ncr in SF6-O2 and SF6-Air mixtures is lower than the measured value in SF6-N2. Parametric studies conducted on these parameters using the Boltzmann analysis offer substantial insight into the plasma physics, as well as a basis to explore the ozone generation process.

Non-native Co-, Mn-, and Ti-oxyhydroxide nanocrystals in ferritin for high efficiency solar energy conversion

NASA Astrophysics Data System (ADS)

Erickson, S. D.; Smith, T. J.; Moses, L. M.; Watt, R. K.; Colton, J. S.

2015-01-01

Quantum dot solar cells seek to surpass the solar energy conversion efficiencies achieved by bulk semiconductors. This new field requires a broad selection of materials to achieve its full potential. The 12 nm spherical protein ferritin can be used as a template for uniform and controlled nanocrystal growth, and to then house the nanocrystals for use in solar energy conversion. In this study, precise band gaps of titanium, cobalt, and manganese oxyhydroxide nanocrystals within ferritin were measured, and a change in band gap due to quantum confinement effects was observed. The range of band gaps obtainable from these three types of nanocrystals is 2.19-2.29 eV, 1.93-2.15 eV, and 1.60-1.65 eV respectively. From these measured band gaps, theoretical efficiency limits for a multi-junction solar cell using these ferritin-enclosed nanocrystals are calculated and found to be 38.0% for unconcentrated sunlight and 44.9% for maximally concentrated sunlight. If a ferritin-based nanocrystal with a band gap similar to silicon can be found (i.e. 1.12 eV), the theoretical efficiency limits are raised to 51.3% and 63.1%, respectively. For a current matched cell, these latter efficiencies become 41.6% (with an operating voltage of 5.49 V), and 50.0% (with an operating voltage of 6.59 V), for unconcentrated and maximally concentrated sunlight respectively.

International Laser Radar Conference (16th) held at the Massachusetts Institute of Technology, Cambridge, Massachusetts on 20-24 July 1992. Part 1

DTIC Science & Technology

1993-07-24

orders smaller than the Rayleigh cross section. We estimated the extinction coefficients of the Pinatubo volcanic aerosol in the stratosphere using a Raman...to a common aerosol parameter (e.g., backscatter coefficients at selected CO2 wavelengths), have all led to similar estimated values of that...increase only as -r 2 . During this phase, therefore, the backscatter coefficient of a coagulating aerosol population decreases as -r- The maximum

Four-Terminal All-Perovskite Tandem Solar Cells Achieving Power Conversion Efficiencies Exceeding 23%

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Dewei; Wang, Changlei; Song, Zhaoning

We report on fabrication of 4-terminal all-perovskite tandem solar cells with power conversion efficiencies exceeding 23% by mechanically stacking semitransparent 1.75 eV wide-bandgap FA 0.8Cs 0.2Pb(I 0.7Br 0.3) 3 perovskite top cells with 1.25 eV low-bandgap (FASnI 3) 0.6(MAPbI 3) 0.4 bottom cells. The top cells use MoOx/ITO transparent electrodes and achieve transmittance up to 70% beyond 700 nm.

Four-Terminal All-Perovskite Tandem Solar Cells Achieving Power Conversion Efficiencies Exceeding 23%

DOE PAGES

Zhao, Dewei; Wang, Changlei; Song, Zhaoning; ...

2018-01-04

We report on fabrication of 4-terminal all-perovskite tandem solar cells with power conversion efficiencies exceeding 23% by mechanically stacking semitransparent 1.75 eV wide-bandgap FA 0.8Cs 0.2Pb(I 0.7Br 0.3) 3 perovskite top cells with 1.25 eV low-bandgap (FASnI 3) 0.6(MAPbI 3) 0.4 bottom cells. The top cells use MoOx/ITO transparent electrodes and achieve transmittance up to 70% beyond 700 nm.

Collisional Dissociation of CO: ab initio Potential Energy Surfaces and Quasiclassical Trajectory Rate Coefficients

NASA Technical Reports Server (NTRS)

Schwenke, David W.; Jaffe, Richard L.; Chaban, Galina M.

2016-01-01

We have generated accurate global potential energy surfaces for CO+Ar and CO+O that correlate with atom-diatom pairs in their ground electronic states based on extensive ab initio electronic structure calculations and used these potentials in quasi-classical trajectory nuclear dynamics calculations to predict the thermal dissociation rate coefficients over 5000- 35000 K. Our results are not compatible with the 20-45 year old experimental results. For CO + Ar we obtain fairly good agreement with the experimental rate coefficients of Appleton et al. (1970) and Mick and Roth (1993), but our computed rate coefficients exhibit a stronger temperature dependence. For CO + O our dissociation rate coefficient is in close agreement with the value from the Park model, which is an empirical adjustment of older experimental results. However, we find the rate coefficient for CO + O is only 1.5 to 3.3 times larger than CO + Ar over the temperature range of the shock tube experiments (8000-15,000 K). The previously accepted value for this rate coefficient ratio is 15, independent of temperature. We also computed the rate coefficient for the CO + O ex- change reaction which forms C + O2. We find this reaction is much faster than previously believed and is the dominant process in the removal of CO at temperatures up to 16,000 K. As a result, the dissociation of CO is accomplished in two steps (react to form C+O2 and then O2 dissociates) that are endothermic by 6.1 and 5.1 eV, instead of one step that requires 11.2 eV to break the CO bond.

Measurement of the Two-photon Absorption Coefficient of Gallium Phosphide (GaP) Using a Dispersion-minimized Sub-10 Femtosecond Z-scan Measurement System

DTIC Science & Technology

2012-09-01

bandwidth of the pulse. Using the standard laboratory and analysis methods of Sheik- Bahae et al., we obtain a two-photon absorption coefficient, β, of...organic thin-film materials deposited on various substrates. 15 6. References 1. Sheik- Bahae , M.; Said, A. A.; Van Stryland, E. W. High...sensitivity, Single-beam n2 Measurements. Optics Letters 1989, 14 (17). 2. Sheik- Bahae , M.; Said, A. A.; Van Stryland, E. W.; Wei, T-H; Hagan, D. J

Acoustic echo cancellation for full-duplex voice transmission on fading channels

NASA Technical Reports Server (NTRS)

Park, Sangil; Messer, Dion D.

1990-01-01

This paper discusses the implementation of an adaptive acoustic echo canceler for a hands-free cellular phone operating on a fading channel. The adaptive lattice structure, which is particularly known for faster convergence relative to the conventional tapped-delay-line (TDL) structure, is used in the initialization stage. After convergence, the lattice coefficients are converted into the coefficients for the TDL structure which can accommodate a larger number of taps in real-time operation due to its computational simplicity. The conversion method of the TDL coefficients from the lattice coefficients is derived and the DSP56001 assembly code for the lattice and TDL structure is included, as well as simulation results and the schematic diagram for the hardware implementation.

On Sound Reflection in Superfluid

NASA Astrophysics Data System (ADS)

Melnikovsky, L. A.

2008-02-01

We consider reflection of first and second sound waves by a rigid flat wall in superfluid. A nontrivial dependence of the reflection coefficients on the angle of incidence is obtained. Sound conversion is predicted at slanted incidence.

Spectroscopic ellipsometry study of Cu2ZnSnS4 bulk poly-crystals

NASA Astrophysics Data System (ADS)

Levcenko, S.; Hajdeu-Chicarosh, E.; Garcia-Llamas, E.; Caballero, R.; Serna, R.; Bodnar, I. V.; Victorov, I. A.; Guc, M.; Merino, J. M.; Pérez-Rodriguez, A.; Arushanov, E.; León, M.

2018-04-01

The linear optical properties of Cu2ZnSnS4 bulk poly-crystals have been investigated using spectroscopic ellipsometry in the range of 1.2-4.6 eV at room temperature. The characteristic features identified in the optical spectra are explained by using the Adachi analytical model for the interband transitions at the corresponding critical points in the Brillouin zone. The experimental data have been modeled over the entire spectral range taking into account the lowest E0 transition near the fundamental absorption edge and E1A and E1B higher energy interband transitions. In addition, the spectral dependences of the refractive index, extinction coefficient, absorption coefficient, and normal-incidence reflectivity values have been accurately determined and are provided since they are essential data for the design of Cu2ZnSnS4 based optoelectronic devices.

Lifetime Measurement of the 229Th nuclear isomer

NASA Astrophysics Data System (ADS)

Seiferle, Benedict; von der Wense, Lars; Thirolf, Peter G.

2017-01-01

The first excited isomeric state of 229Th possesses the lowest energy among all known excited nuclear states. The expected energy is accessible with today's laser technology and in principle allows for a direct optical laser excitation of the nucleus. The isomer decays via three channels to its ground state (internal conversion, γ decay, and bound internal conversion), whose strengths depend on the charge state of Thm229 . We report on the measurement of the internal-conversion decay half-life of neutral Thm229 . A half-life of 7 ±1 μ s has been measured, which is in the range of theoretical predictions and, based on the theoretically expected lifetime of ≈1 04 s of the photonic decay channel, gives further support for an internal conversion coefficient of ≈1 09, thus constraining the strength of a radiative branch in the presence of internal conversion.

Enhanced energy harvesting by concentration gradient-driven ion transport in SBA-15 mesoporous silica thin films.

PubMed

Hwang, Junho; Kataoka, Sho; Endo, Akira; Daiguji, Hirofumi

2016-09-21

Nanofluidic energy harvesting systems have attracted interest in the field of battery application, particularly for miniaturized electrical devices, because they possess excellent energy conversion capability for their size. In this study, a mesoporous silica (MPS)-based nanofluidic energy harvesting system was fabricated and selective ion transport in mesopores as a function of the salt gradient was investigated. Aqueous solutions with three different kinds of monovalent electrolytes-KCl, NaCl, and LiCl-with different diffusion coefficients (D + ) were considered. The highest power density was 3.90 W m -2 for KCl, followed by 2.39 W m -2 for NaCl and 1.29 W m -2 for LiCl. Furthermore, the dependency of power density on the type of cation employed indicates that the harvested energy increases as the cation mobility increases, particularly at high concentrations. This cation-specific dependency suggests that the maximum power density increases by increasing the diffusion coefficient ratio of cations to anions, making this ratio a critical parameter in enhancing the performance of nanofluidic energy harvesting systems with extremely small pores ranging from 2 to 3 nm.

Quantitative structure-activity relationship for the partition coefficient of hydrophobic compounds between silicone oil and air.

PubMed

Qu, Yanfei; Ma, Yongwen; Wan, Jinquan; Wang, Yan

2018-06-01

The silicon oil-air partition coefficients (K SiO/A ) of hydrophobic compounds are vital parameters for applying silicone oil as non-aqueous-phase liquid in partitioning bioreactors. Due to the limited number of K SiO/A values determined by experiment for hydrophobic compounds, there is an urgent need to model the K SiO/A values for unknown chemicals. In the present study, we developed a universal quantitative structure-activity relationship (QSAR) model using a sequential approach with macro-constitutional and micromolecular descriptors for silicone oil-air partition coefficients (K SiO/A ) of hydrophobic compounds with large structural variance. The geometry optimization and vibrational frequencies of each chemical were calculated using the hybrid density functional theory at the B3LYP/6-311G** level. Several quantum chemical parameters that reflect various intermolecular interactions as well as hydrophobicity were selected to develop QSAR model. The result indicates that a regression model derived from logK SiO/A , the number of non-hydrogen atoms (#nonHatoms) and energy gap of E LUMO and E HOMO (E LUMO -E HOMO ) could explain the partitioning mechanism of hydrophobic compounds between silicone oil and air. The correlation coefficient R 2 of the model is 0.922, and the internal and external validation coefficient, Q 2 LOO and Q 2 ext , are 0.91 and 0.89 respectively, implying that the model has satisfactory goodness-of-fit, robustness, and predictive ability and thus provides a robust predictive tool to estimate the logK SiO/A values for chemicals in application domain. The applicability domain of the model was visualized by the Williams plot.

Hydraulic and Mechanical Effects from Gas Hydrate Conversion and Secondary Gas Hydrate Formation during Injection of CO2 into CH4-Hydrate-Bearing Sediments

NASA Astrophysics Data System (ADS)

Bigalke, N.; Deusner, C.; Kossel, E.; Schicks, J. M.; Spangenberg, E.; Priegnitz, M.; Heeschen, K. U.; Abendroth, S.; Thaler, J.; Haeckel, M.

2014-12-01

The injection of CO2 into CH4-hydrate-bearing sediments has the potential to drive natural gas production and simultaneously sequester CO2 by hydrate conversion. The process aims at maintaining the in situ hydrate saturation and structure and causing limited impact on soil hydraulic properties and geomechanical stability. However, to increase hydrate conversion yields and rates it must potentially be assisted by thermal stimulation or depressurization. Further, secondary formation of CO2-rich hydrates from pore water and injected CO2 enhances hydrate conversion and CH4 production yields [1]. Technical stimulation and secondary hydrate formation add significant complexity to the bulk conversion process resulting in spatial and temporal effects on hydraulic and geomechanical properties that cannot be predicted by current reservoir simulation codes. In a combined experimental and numerical approach, it is our objective to elucidate both hydraulic and mechanical effects of CO2 injection and CH4-CO2-hydrate conversion in CH4-hydrate bearing soils. For the experimental approach we used various high-pressure flow-through systems equipped with different online and in situ monitoring tools (e.g. Raman microscopy, MRI and ERT). One particular focus was the design of triaxial cell experimental systems, which enable us to study sample behavior even during large deformations and particle flow. We present results from various flow-through high-pressure experimental studies on different scales, which indicate that hydraulic and geomechanical properties of hydrate-bearing sediments are drastically altered during and after injection of CO2. We discuss the results in light of the competing processes of hydrate dissociation, hydrate conversion and secondary hydrate formation. Our results will also contribute to the understanding of effects of temperature and pressure changes leading to dissociation of gas hydrates in ocean and permafrost systems. [1] Deusner C, Bigalke N, Kossel E, Haeckel M. Methane Production from Gas Hydrate Deposits through Injection of Supercritical CO2. Energies 2012:5(7): 2112-2140.

Method for conversion of .beta.-hydroxy carbonyl compounds

DOEpatents

Lilga, Michael A.; White, James F.; Holladay, Johnathan E.; Zacher, Alan H.; Muzatko, Danielle S.; Orth, Rick J.

2010-03-30

A process is disclosed for conversion of salts of .beta.-hydroxy carbonyl compounds forming useful conversion products including, e.g., .alpha.,.beta.-unsaturated carbonyl compounds and/or salts of .alpha.,.beta.-unsaturated carbonyl compounds. Conversion products find use, e.g., as feedstock and/or end-use chemicals.

Microbial responses to disturbance following the conversion of CRP land to cropland under water limiting conditions

USDA-ARS?s Scientific Manuscript database

The conversion of Conservation Reserve Program (CRP) lands to croplands potentially reduces ecological benefits such as high soil health condition that resist to disturbance (i.e. extreme weather). Soil CO2 flux primarily comes from root and microbes’ respirations and is sensitive to changes in soil...

Study of the Dalitz decay ϕ → ηe+e- with the KLOE detector

NASA Astrophysics Data System (ADS)

Babusci, D.; Balwierz-Pytko, I.; Bencivenni, G.; Bloise, C.; Bossi, F.; Branchini, P.; Budano, A.; Caldeira Balkeståhl, L.; Ceradini, F.; Ciambrone, P.; Curciarello, F.; Czerwiński, E.; Danè, E.; De Leo, V.; De Lucia, E.; De Robertis, G.; De Santis, A.; De Simone, P.; Di Cicco, A.; Di Domenico, A.; Di Salvo, R.; Domenici, D.; Erriquez, O.; Fanizzi, G.; Fantini, A.; Felici, G.; Fiore, S.; Franzini, P.; Gajos, A.; Gauzzi, P.; Giardina, G.; Giovannella, S.; Graziani, E.; Happacher, F.; Heijkenskjöld, L.; Höistad, B.; Johansson, T.; Kamińska, D.; Krzemien, W.; Kupsc, A.; Lee-Franzini, J.; Loddo, F.; Loffredo, S.; Mandaglio, G.; Martemianov, M.; Martini, M.; Mascolo, M.; Messi, R.; Miscetti, S.; Morello, G.; Moricciani, D.; Moskal, P.; Palladino, A.; Passeri, A.; Patera, V.; Prado Longhi, I.; Ranieri, A.; Santangelo, P.; Sarra, I.; Schioppa, M.; Sciascia, B.; Silarski, M.; Tortora, L.; Venanzoni, G.; Wiślicki, W.; Wolke, M.

2015-03-01

We have studied the vector to pseudoscalar conversion decay ϕ → ηe+e-, with η →π0π0π0, with the KLOE detector at DAΦNE. The data set of 1.7 fb-1 of e+e- collisions at √{ s} ∼Mϕ contains a clear conversion decay signal of ∼ 31 , 000 events from which we measured a value of BR (ϕ → ηe+e-) = (1.075 ± 0.007 ± 0.038) ×10-4. The same sample is used to determine the transition form factor by a fit to the e+e- invariant mass spectrum, obtaining bϕη = (1.28 ±0.10-0.08+0.09) GeV-2, that improves by a factor of five the precision of the previous measurement and is in good agreement with VMD expectations.

Computational Chemical Kinetics for the Reaction of Criegee Intermediate CH2OO with HNO3 and Its Catalytic Conversion to OH and HCO.

PubMed

Raghunath, P; Lee, Yuan-Pern; Lin, M C

2017-05-25

The kinetics and mechanisms for the reaction of the Criegee intermediate CH 2 OO with HNO 3 and the unimolecular decomposition of its reaction product CH 2 (O)NO 3 are important in atmospheric chemistry. The potential-energy profile of the reactions predicted with the CCSD(T)/aug-cc-pVTZ//B3LYP/aug-cc-pVTZ method shows that the initial association yields a prereaction complex that isomerizes by H migration to yield excited intermediate nitrooxymethyl hydroperoxide NO 3 CH 2 OOH* with internal energy ∼44 kcal mol -1 . A fragmentation of this excited intermediate produces CH 2 (O)NO 3 + OH with its transition state located 5.0 kcal mol -1 below that of the reactants. Further decomposition of CH 2 (O)NO 3 produces HCO + HNO 3 , forming a catalytic cycle for destruction of CH 2 OO by HNO 3 . The rate coefficients and product-branching ratios were calculated in the temperature range 250-700 K at pressure 20-760 Torr (N 2 ) using the variational-transition-state and Rice-Ramsperger-Kassel-Marcus (RRKM) theories. The predicted total rate coefficient for reaction CH 2 OO + HNO 3 at 295 K, 5.1 × 10 -10 cm 3 molecule -1 s -1 , agrees satisfactorily with the experimental value, (5.4 ± 1.0) × 10 -10 cm 3 molecule -1 s -1 . The predicted branching ratios at 295 K are 0.21 for the formation of NO 3 CH 2 OOH and 0.79 for CH 2 (O)NO 3 + OH at a pressure of 40 Torr (N 2 ), and 0.79 for the formation of NO 3 CH 2 OOH and 0.21 for CH 2 (O)NO 3 + OH at 760 Torr (N 2 ). This new catalytic conversion of CH 2 OO to HCO + OH by HNO 3 might have significant impact on atmospheric chemistry.

Measurements of octanol-air partition coefficients, vapor pressures and vaporization enthalpies of the (E) and (Z) isomers of the 2-ethylhexyl 4-methoxycinnamate as parameters of environmental impact assessment.

PubMed

Pegoraro, César N; Chiappero, Malisa S; Montejano, Hernán A

2015-11-01

2-Ethylhexyl 4-methoxycinnamate is one of the UVB blocking agents more widely used in a variety of industrial fields. There are more than one hundred industrial suppliers worldwide. Given the enormous annual consumption of octinoxate, problems that arise due to the accumulation of this compound in nature should be taken into consideration. The GC-RT was used in this work with the aim of determining the vapor pressure, enthalpies of vaporization and octanol-air partition coefficient, for the BBP, DOP, E- and Z-EHMC esters. The results showed that Z-EHMC is almost five times more volatile than E-EHMC. Moreover, BBP, Z-EHMC and E-EHMC can be classified as substances with a relatively low mobility since they lie within the range of 810 and log(PL/Pa)<-4, therefore, a low mobility can be expected. From these parameters, their particle-bound fraction and gas-particle partition coefficient were also derived. Copyright © 2015 Elsevier Ltd. All rights reserved.

Computational study of collisions between O({sup 3}P) and NO({sup 2}Π) at temperatures relevant to the hypersonic flight regime

DOE Office of Scientific and Technical Information (OSTI.GOV)

Castro-Palacio, Juan Carlos; Nagy, Tibor; Meuwly, Markus, E-mail: m.meuwly@unibas.ch

2014-10-28

Reactions involving N and O atoms dominate the energetics of the reactive air flow around spacecraft when reentering the atmosphere in the hypersonic flight regime. For this reason, the thermal rate coefficients for reactive processes involving O({sup 3}P) and NO({sup 2}Π) are relevant over a wide range of temperatures. For this purpose, a potential energy surface (PES) for the ground state of the NO{sub 2} molecule is constructed based on high-level ab initio calculations. These ab initio energies are represented using the reproducible kernel Hilbert space method and Legendre polynomials. The global PES of NO{sub 2} in the ground statemore » is constructed by smoothly connecting the surfaces of the grids of various channels around the equilibrium NO{sub 2} geometry by a distance-dependent weighting function. The rate coefficients were calculated using Monte Carlo integration. The results indicate that at high temperatures only the lowest A-symmetry PES is relevant. At the highest temperatures investigated (20 000 K), the rate coefficient for the “O1O2+N” channel becomes comparable (to within a factor of around three) to the rate coefficient of the oxygen exchange reaction. A state resolved analysis shows that the smaller the vibrational quantum number of NO in the reactants, the higher the relative translational energy required to open it and conversely with higher vibrational quantum number, less translational energy is required. This is in accordance with Polanyi's rules. However, the oxygen exchange channel (NO2+O1) is accessible at any collision energy. Finally, this work introduces an efficient computational protocol for the investigation of three-atom collisions in general.« less

Computational study of collisions between O(3P) and NO(2Π) at temperatures relevant to the hypersonic flight regime.

PubMed

Castro-Palacio, Juan Carlos; Nagy, Tibor; Bemish, Raymond J; Meuwly, Markus

2014-10-28

Reactions involving N and O atoms dominate the energetics of the reactive air flow around spacecraft when reentering the atmosphere in the hypersonic flight regime. For this reason, the thermal rate coefficients for reactive processes involving O((3)P) and NO((2)Π) are relevant over a wide range of temperatures. For this purpose, a potential energy surface (PES) for the ground state of the NO2 molecule is constructed based on high-level ab initio calculations. These ab initio energies are represented using the reproducible kernel Hilbert space method and Legendre polynomials. The global PES of NO2 in the ground state is constructed by smoothly connecting the surfaces of the grids of various channels around the equilibrium NO2 geometry by a distance-dependent weighting function. The rate coefficients were calculated using Monte Carlo integration. The results indicate that at high temperatures only the lowest A-symmetry PES is relevant. At the highest temperatures investigated (20,000 K), the rate coefficient for the "O1O2+N" channel becomes comparable (to within a factor of around three) to the rate coefficient of the oxygen exchange reaction. A state resolved analysis shows that the smaller the vibrational quantum number of NO in the reactants, the higher the relative translational energy required to open it and conversely with higher vibrational quantum number, less translational energy is required. This is in accordance with Polanyi's rules. However, the oxygen exchange channel (NO2+O1) is accessible at any collision energy. Finally, this work introduces an efficient computational protocol for the investigation of three-atom collisions in general.

Characterizing light attenuation within Northwest Florida ...

EPA Pesticide Factsheets

Water Quality (WQ) condition is based on ecosystem stressor indicators (e.g. water clarity) which are biogeochemically important and critical when considering the Deepwater Horizon oil spill restoration efforts under the 2012 RESTORE Act. Nearly all of the proposed RESTORE projects list restoring WC as a goal, but 90% neglect water clarity. Here, dynamics of optical constituents impacting clarity are presented from a 2009-2011 study within Pensacola, Choctawhatchee, St. Andrew and St. Joseph estuaries (targeted RESTORE sites) in Northwest Florida. Phytoplankton were the smallest contribution to total absorption (at-wPAR) at 412 nm (5-11%), whereas colored dissolved organic matter was the largest (61-79%). Estuarine at-wPAR was significantly related to light attenuation (KdPAR), where individual contributors to clarity and the influence of climatic events were discerned. Provided are conversion equations demonstrating interoperability of clarity indicators between traditional State-measured WQ measures (e.g. secchi disc), optical constituents, and even satellite remote sensing for obtaining baseline assessments. This paper arose from efforts under SSWR and SHC to utilize water quality data as baseline measures for RESTORE Act monitoring in Florida estuaries. This paper aims to (1) describe dynamics of optical constituents that impact water clarity in four NW Florida estuaries, and (2) make a case for the total absorption coefficient (at-wPAR) as a valuable

A Reactive-Heat-Pipe for Combined Heat Generation and Transport

DTIC Science & Technology

1977-12-01

The Lennard - Jones potential parameters a and F-1 can be found in Ar Ar Table 2.3 of Reference [26]. They are a Ar =3.542 A ~Ar -=93.3 K The above...Specific Heat Ratio Wire Spacing of Screen S Volume Fraction of Solid Phase in Wick or Lennard Jones Force Constant e’ Wick Void Fraction 1Viscusity p...Density a Surface Tension G Condensation Coefficient c e Evaporation Coefficient*e U Lennard - Jones Force Constant Subscripts A Position A in Figure 13 Ar

Thruput Analysis of AFLC CYBER 73 Computers.

DTIC Science & Technology

1981-12-01

Ref 2:14). This decision permitted a fast conversion effort with minimum programmer/analyst experience (Ref 34). Recently, as the conversion effort...converted (Ref 1:2). 2 . i i i II I i4 Moreover, many of the large data-file and machine-time- consuming systems were not included in the earlier...by LMT personnel revealed that during certain periods i.e., 0000-0800, the machine is normally reserved for the large 3 4 resource- consuming programs

VizieR Online Data Catalog: Rate coefficients for H2(v,j)+H2(v',j'

NASA Astrophysics Data System (ADS)

Mandy, M. E.

2016-11-01

State-specific rate coefficients for the dissociation of H2 result of collisions with H2 were calculated for all combinations of (v,j) with an internal energy below 1eV. Full-dimensional quasiclassical trajectories were calculated using the BMKP2 interaction potential with a minimum of 80000 trajectories at each translational energy. Additional large batches of trajectories were carried out to calculate the cross sections near the threshold to dissociation to attain the desired precision of the rate coefficients. A piecewise linear excitation function was used to calculate the rate coefficient between 100 and 100000K. The resulting state-specific rate coefficients, γ, were parametrized as a function of temperature over the range 600-10000K using: log10γ(t)=a+bz+cz2-d(1/t-1) where t=T/4500K and z=log10t. The values of the resulting rate coefficients were sensitive to the internal energy of both molecules, with initial vibrational energy having a slightly greater effect than rotational energy. This effect diminished as temperature increased. (15 data files).

Role of Er3+ concentration in spectroscopic and laser performance of CaYAlO4 crystal

NASA Astrophysics Data System (ADS)

Lv, Shaozhen; Wang, Yan; Zhu, Zhaojie; You, Zhenyu; Li, Jianfu; Wang, Hongyan; Tu, Chaoyang

2015-04-01

Three heavily Er3+-doped CaYAlO4 single crystals were successfully grown by Czochralski method. The emission spectra and the fluorescence decay curves have been recorded at room temperature. A combination of experimental data, rate equation and Dexter theory are used to investigate the influence of Er3+ doping concentration on the spectra character and the inner cross relaxation of Er3+:CaYAlO4 crystal. Results show that the self terminate effect of the transition 4I11/2 → 4I13/2 can be suppressed by heavy Er3+doping. But if the doping concentration goes too high, the much larger cross relaxation coefficient of 4I11/2 level than that of 4I13/2 level would results in the increase of up-conversion emission and the quench of near and mid infrared emission. The laser performance was also studied. The maximum output power of 225 mW at 2733 nm was acquired with an optical conversion efficiency of 14.9%.

High-Quality (CH3NH3)3Bi2I9 Film-Based Solar Cells: Pushing Efficiency up to 1.64.

PubMed

Zhang, Zheng; Li, Xiaowei; Xia, Xiaohong; Wang, Zhuo; Huang, Zhongbing; Lei, Binglong; Gao, Yun

2017-09-07

Bismuth-based solar cells have exhibited some advantages over lead perovskite solar cells for nontoxicity and superior stability, which are currently two main concerns in the photovoltaic community. As for the perovskite-related compound (CH 3 NH 3 ) 3 Bi 2 I 9 applied for solar cells, the conversion efficiency is severely restricted by the unsatisfactory photoactive film quality. Herein we report a novel two-step approach- high-vacuum BiI 3 deposition and low-vacuum homogeneous transformation of BiI 3 to (CH 3 NH 3 ) 3 Bi 2 I 9 -for highly compact, pinhole-free, large-grained films, which are characterized with absorption coefficient, trap density of states, and charge diffusion length comparable to those of some lead perovskite analogues. Accordingly, the solar cells have realized a record power conversion of efficiency of 1.64% and also a high external quantum efficiency approaching 60%. Our work demonstrates the potential of (CH 3 NH 3 ) 3 Bi 2 I 9 for highly efficient and long-term stable solar cells.

On the conversion of tritium units to mass fractions for hydrologic applications

USGS Publications Warehouse

Stonestrom, David A.; Andraski, Brian J.; Cooper, Clay A.; Mayers, Charles J.; Michel, Robert L.

2013-01-01

We develop a general equation for converting laboratory-reported tritium levels, expressed either as concentrations (tritium isotope number fractions) or mass-based specific activities, to mass fractions in aqueous systems. Assuming that all tritium is in the form of monotritiated water simplifies the derivation and is shown to be reasonable for most environmental settings encountered in practice. The general equation is nonlinear. For tritium concentrations c less than 4.5×1012 tritium units (TU) - i.e. specific tritium activities11 Bq kg-1 - the mass fraction w of tritiated water is approximated to within 1 part per million by w ≈ c×2.22293×10-18, i.e. the conversion is linear for all practical purposes. Terrestrial abundances serve as a proxy for non-tritium isotopes in the absence of sample-specific data. Variation in the relative abundances of non-tritium isotopes in the terrestrial hydrosphere produces a minimum range for the mantissa of the conversion factor of [2.22287; 2.22300].

Asymptotic normalization coefficients and radiative widths

NASA Astrophysics Data System (ADS)

Mukhamedzhanov, A. M.; Pang, D. Y.

2015-07-01

The asymptotic normalization coefficient (ANC) is an important quantity in the calculation of radiative width amplitudes, providing limits on the radiative width. Here we present some examples showing the connection between the ANC and radiative width. In particular, the radiative width of the E 1 transition 17F(1 /2-,Ex=3.104 MeV ) to 17F(1 /2+,Ex=0.495 MeV ) reported by Rolfs [Nucl. Phys. A 217, 29 (1973), 10.1016/0375-9474(73)90622-2] is (1.2 ±0.2 ) ×10-2 eV. Meanwhile the ANC for the first excited state in 17F puts a lower limit on the radiative width, which is (3.4 ±0.50 ) ×10-2 eV. Such a strong disagreement between the measured radiative width and the lower limit imposed by the ANC calls for a new measurement of this radiative width. Other examples are also considered.

Photoinduced Reductive Elimination of H2 from the Nitrogenase Dihydride (Janus) State Involves a FeMo-cofactor-H2 Intermediate.

PubMed

Lukoyanov, Dmitriy; Khadka, Nimesh; Dean, Dennis R; Raugei, Simone; Seefeldt, Lance C; Hoffman, Brian M

2017-02-20

N 2 reduction by nitrogenase involves the accumulation of four reducing equivalents at the active site FeMo-cofactor to form a state with two [Fe-H-Fe] bridging hydrides (denoted E 4 (4H), the Janus intermediate), and we recently demonstrated that the enzyme is activated to cleave the N≡N triple bond by the reductive elimination (re) of H 2 from this state. We are exploring a photochemical approach to obtaining atomic-level details of the re activation process. We have shown that, when E 4 (4H) at cryogenic temperatures is subjected to 450 nm irradiation in an EPR cavity, it cleanly undergoes photoinduced re of H 2 to give a reactive doubly reduced intermediate, denoted E 4 (2H)*, which corresponds to the intermediate that would form if thermal dissociative re loss of H 2 preceded N 2 binding. Experiments reported here establish that photoinduced re primarily occurs in two steps. Photolysis of E 4 (4H) generates an intermediate state that undergoes subsequent photoinduced conversion to [E 4 (2H)* + H 2 ]. The experiments, supported by DFT calculations, indicate that the trapped intermediate is an H 2 complex on the ground adiabatic potential energy suface that connects E 4 (4H) with [E 4 (2H)* + H 2 ]. We suggest that this complex, denoted E 4 (H 2 ; 2H), is a thermally populated intermediate in the catalytically central re of H 2 by E 4 (4H) and that N 2 reacts with this complex to complete the activated conversion of [E 4 (4H) + N 2 ] into [E 4 (2N2H) + H 2 ].

Photoinduced Reductive Elimination of H 2 from the Nitrogenase Dihydride (Janus) State Involves a FeMo-cofactor-H 2 Intermediate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lukoyanov, Dmitriy; Khadka, Nimesh; Dean, Dennis R.

N2 reduction by nitrogenase involves the accumulation of four reducing equivalents at the active site FeMo-cofactor to form a state with two [Fe-H-Fe] bridging hydrides (denoted E4(4H), the Janus intermediate), and we recently demonstrated that the enzyme is activated to cleave the N≡N triple bond by the reductive elimination (re) of H2 from this state. We are exploring a photochemical approach to obtaining atomic-level details of the re activation process. We have shown that when E4(4H) at cryogenic temperatures is subjected to 450 nm irradiation in an EPR cavity, it cleanly undergoes photoinduced re of H2 to give a reactivemore » doubly-reduced intermediate, denoted E4(2H)*, which corresponds to the intermediate that would form if thermal dissociative re loss of H2 preceded N2 binding. Experiments reported here establish that photoinduced re occurs in two steps. Photolysis of E4(4H) generates an intermediate state that undergoes subsequent photoinduced conversion to [E4(2H)* + H2]. The experiments, supported by DFT calculation, indicate that the trapped intermediate is an H2 complex on the ground adiabatic potential energy suface that connects E4(4H) with [E4(2H)* + H2]. We suggest this complex, denoted E4(H2; 2H), is a thermally populated intermediate in the catalytically central re of H2 by E4(4H), and that N2 reacts with this complex to complete the activated conversion of [E4(4H) + N2] into [E4(2N2H) + H2].« less

Sulfidation treatment of molten incineration fly ashes with Na2S for zinc, lead and copper resource recovery.

PubMed

Kuchar, D; Fukuta, T; Onyango, M S; Matsuda, H

2007-04-01

The present study focuses on the conversion of heavy metals involved in molten incineration fly ashes to metal sulfides which could be thereafter separated by flotation. The sulfidation treatment was carried out for five molten incineration fly ashes (Fly ash-A to Fly ash-E) by contacting each fly ash with Na(2)S solution for a period of 10 min to 6h. The initial molar ratio of S(2-) to Me(2+) was adjusted to 1.20. The conversion of heavy metals to metal sulfides was evaluated by measuring the S(2-) residual concentrations using an ion selective electrode. The formation of metal sulfides was studied by XRD and SEM-EDS analyses. In the case of Fly ash-A to Fly ash-D, more than 79% of heavy metals of zinc, lead and copper was converted to metal sulfides within the contacting period of 0.5h owing to a fast conversion of metal chlorides to metal sulfides. By contrast, the conversion of about 35% was achieved for Fly ash-E within the same contacting period, which was attributed to a high content of metal oxides. Further, the S(2-) to Me(2+) molar ratio was reduced to 1.00 to minimize Na(2)S consumption and the conversions obtained within the contacting period of 0.5h varied from 76% for Fly ash-D to 91% for Fly ash-C. Finally, soluble salts such as NaCl and KCl were removed during the sulfidation treatment, which brought about a significant enrichment in metals content by a factor varying from 1.5 for Fly ash-D to 4.9 for Fly ash-A.

Optical Absorption Spectra of Hydrogenated Microcrystalline Silicon Films by Resonant Photothermal Bending Spectroscopy

NASA Astrophysics Data System (ADS)

Kunii, Toshie; Yoshida, Norimitsu; Hori, Yasuro; Nonomura, Shuichi

2006-05-01

A resonant photothermal bending spectroscopy (PBS) is demonstrated for the measurement of absorption coefficient spectra in hydrogenated microcrystalline silicon (μc-Si:H) and hydrogenated microcrystalline cubic silicon carbide (μc-3C-SiC:H) films. The resonant vibration technique utilized in PBS establishes the sensitivity as α d˜ 5× 10-5 in a vacuum measurement. Appling resonant PBS to μc-Si:H films, a new extra absorption coefficient αex spectrum is observed from 0.6 to 1.2 eV. The αex spectrum has a peak at ˜1.0 eV, and the localized states inducing the αex are located ˜0.35 eV below the conduction band edge of μc-Si:H. A possible explanation for the observed localized state is that an oxidation produces weak bonds at the grain boundaries and/or amorphous silicon tissues. In μc-3C-SiC:H film, an optical band-gap energy of ˜2.2 eV was demonstrated assuming an indirect optical transition. The temperature coefficient of the optical band-gap energy was ˜2.3× 10-4 eV K-1. The αex spectrum of μc-3C-SiC:H film is plateau-shaped and its magnitude is in accord with an increase in grain size.

Cap integration in spectral gravity forward modelling: near- and far-zone gravity effects via Molodensky's truncation coefficients

NASA Astrophysics Data System (ADS)

Bucha, Blažej; Hirt, Christian; Kuhn, Michael

2018-04-01

Spectral gravity forward modelling is a technique that converts a band-limited topography into its implied gravitational field. This conversion implicitly relies on global integration of topographic masses. In this paper, a modification of the spectral technique is presented that provides gravity effects induced only by the masses located inside or outside a spherical cap centred at the evaluation point. This is achieved by altitude-dependent Molodensky's truncation coefficients, for which we provide infinite series expansions and recurrence relations with a fixed number of terms. Both representations are generalized for an arbitrary integer power of the topography and arbitrary radial derivative. Because of the altitude-dependency of the truncation coefficients, a straightforward synthesis of the near- and far-zone gravity effects at dense grids on irregular surfaces (e.g. the Earth's topography) is computationally extremely demanding. However, we show that this task can be efficiently performed using an analytical continuation based on the gradient approach, provided that formulae for radial derivatives of the truncation coefficients are available. To demonstrate the new cap-modified spectral technique, we forward model the Earth's degree-360 topography, obtaining near- and far-zone effects on gravity disturbances expanded up to degree 3600. The computation is carried out on the Earth's surface and the results are validated against an independent spatial-domain Newtonian integration (1 μGal RMS agreement). The new technique is expected to assist in mitigating the spectral filter problem of residual terrain modelling and in the efficient construction of full-scale global gravity maps of highest spatial resolution.

Aqueous phase preparation of ultrasmall MoSe2 nanodots for efficient photothermal therapy of cancer cells

NASA Astrophysics Data System (ADS)

Yuwen, Lihui; Zhou, Jiajia; Zhang, Yuqian; Zhang, Qi; Shan, Jingyang; Luo, Zhimin; Weng, Lixing; Teng, Zhaogang; Wang, Lianhui

2016-01-01

Photothermal therapy (PTT) is a promising cancer treatment with both high effectiveness and fewer side effects. However, an ideal PTT agent not only needs strong absorption of near-infrared (NIR) light and high photothermal conversion efficiency, but also needs good biocompatibility, stability, and small size, which makes the design and preparation of a novel PTT agent a great challenge. In this work, we developed an ultrasonication-assisted liquid exfoliation method for the direct preparation of ultrasmall (2-3 nm) MoSe2 nanodots (NDs) in aqueous solution and demonstrated their superior properties as a PTT agent. The as-prepared MoSe2 NDs have strong absorption of NIR light and high photothermal conversion efficiency of about 46.5%. In vitro cellular experiments demonstrate that MoSe2 NDs have negligible cytotoxicity and can efficiently kill HeLa cells (human cervical cell line) under NIR laser (785 nm) irradiation.Photothermal therapy (PTT) is a promising cancer treatment with both high effectiveness and fewer side effects. However, an ideal PTT agent not only needs strong absorption of near-infrared (NIR) light and high photothermal conversion efficiency, but also needs good biocompatibility, stability, and small size, which makes the design and preparation of a novel PTT agent a great challenge. In this work, we developed an ultrasonication-assisted liquid exfoliation method for the direct preparation of ultrasmall (2-3 nm) MoSe2 nanodots (NDs) in aqueous solution and demonstrated their superior properties as a PTT agent. The as-prepared MoSe2 NDs have strong absorption of NIR light and high photothermal conversion efficiency of about 46.5%. In vitro cellular experiments demonstrate that MoSe2 NDs have negligible cytotoxicity and can efficiently kill HeLa cells (human cervical cell line) under NIR laser (785 nm) irradiation. Electronic supplementary information (ESI) available: Characterization, size distribution and EDS spectrum of MoSe2 NDs, calculation of the extinction coefficient and photothermal conversion efficiency of MoSe2 NDs. See DOI: 10.1039/c5nr08166a

Theoretical Efficiency of 3rd Generation Solar Cells: Comparison between Carrier Multiplication and Down-Conversion

DTIC Science & Technology

2012-01-01

rewrite this equation using a generalization of Eq. (6), for a given multiplicity mrM : ym Z 1 mEg E2dE eE=kTS1 Z 1 Eg E2dE eE=kTS1 ð13Þ Note that...vectorized quadrature algorithms . We used the quadgk function in Matlab to evaluate all function, since it is best at handling the pole at EqV¼0 in the

Pilot Analysis of Late Conversion to Belatacept in Kidney Transplant Recipients for Biopsy-Proven Chronic Tacrolimus Toxicity

PubMed Central

Rosales, Ivy

2018-01-01

Background Calcineurin inhibitors are associated with chronic nephrotoxicity, manifesting as interstitial fibrosis/tubular atrophy (IF/TA) and arteriolar hyalinosis. Conversion from tacrolimus to belatacept may be one strategy to preserve renal function. Methods We conducted a retrospective review of renal transplant patients followed at our institution who were converted to belatacept and found to have chronic tacrolimus toxicity on biopsy. The primary outcome was eGFR at conversion as compared to eGFR at 3, 6, 12, and 24 months after conversion. We also assessed incidence of infection and rates of allograft survival at 1 year. Results The average time between transplant and conversion was 11.9 years. There was no decrease in eGFR at any postconversion time point as compared with preconversion. The mean eGFR at time of preconversion was 32.9 mL/min, as compared with 35.6 mL/min at 3 months (p = 0.09), 34.1 mL/min at 6 months (p = 0.63), 34.9 mL/min at 12 months (p = 0.57), and 39.6 mL/min at 24 months after conversion (p = 0.92). Four of 7 patients had increases in their eGFR after conversion. All grafts were functioning at 1 year after conversion. Conclusion While this study was limited by a small number of patients, belatacept conversion stabilized eGFR at all time points in patients with late allograft function due to chronic tacrolimus toxicity, with a trend towards increased eGFR at 3 months. PMID:29854421

Konstantinov effect in helium II

NASA Astrophysics Data System (ADS)

Melnikovsky, L. A.

2008-04-01

The reflection of first and second sound waves by a rigid flat wall in helium II is considered. A nontrivial dependence of the reflection coefficients on the angle of incidence is obtained. Sound conversion is predicted at oblique incidence.

Conversion of evanescent Lamb waves into propagating waves via a narrow aperture edge.

PubMed

Yan, Xiang; Yuan, Fuh-Gwo

2015-06-01

This paper presents a quantitative study of conversion of evanescent Lamb waves into propagating in isotropic plates. The conversion is substantiated by prescribing time-harmonic Lamb displacements/tractions through a narrow aperture at an edge of a semi-infinite plate. Complex-valued dispersion and group velocity curves are employed to characterize the conversion process. The amplitude coefficient of the propagating Lamb modes converted from evanescent is quantified based on the complex reciprocity theorem via a finite element analysis. The power flow generated into the plate can be separated into radiative and reactive parts made on the basis of propagating and evanescent Lamb waves, where propagating Lamb waves are theoretically proved to radiate pure real power flow, and evanescent Lamb waves carry reactive pure imaginary power flow. The propagating power conversion efficiency is then defined to quantitatively describe the conversion. The conversion efficiency is strongly frequency dependent and can be significant. With the converted propagating waves from evanescent, sensors at far-field can recapture some localized damage information that is generally possessed in evanescent waves and may have potential application in structural health monitoring.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tom, N.; Lawson, M.; Yu, Y. H.

WEC-Sim is a midfidelity numerical tool for modeling wave energy conversion devices. The code uses the MATLAB SimMechanics package to solve multibody dynamics and models wave interactions using hydrodynamic coefficients derived from frequency-domain boundary-element methods. This paper presents the new modeling features introduced in the latest release of WEC-Sim. The first feature discussed conversion of the fluid memory kernel to a state-space form. This enhancement offers a substantial computational benefit after the hydrodynamic body-to-body coefficients are introduced and the number of interactions increases exponentially with each additional body. Additional features include the ability to calculate the wave-excitation forces based onmore » the instantaneous incident wave angle, allowing the device to weathervane, as well as import a user-defined wave elevation time series. A review of the hydrodynamic theory for each feature is provided and the successful implementation is verified using test cases.« less

COMPILATION OF CONVERSION COEFFICIENTS FOR THE DOSE TO THE LENS OF THE EYE

PubMed Central

2017-01-01

Abstract A compilation of fluence-to-absorbed dose conversion coefficients for the dose to the lens of the eye is presented. The compilation consists of both previously published data and newly calculated values: photon data (5 keV–50 MeV for both kerma approximation and full electron transport), electron data (10 keV–50 MeV), and positron data (1 keV–50 MeV) – neutron data will be published separately. Values are given for angles of incidence from 0° up to 90° in steps of 15° and for rotational irradiation. The data presented can be downloaded from this article's website and they are ready for use by Report Committee (RC) 26. This committee has been set up by the International Commission on Radiation Units and Measurements (ICRU) and is working on a ‘proposal for a redefinition of the operational quantities for external radiation exposure’. PMID:27542816

Self-Inversion of the Image of a Small-Scale Opaque Object in the Process of Focusing of the Illuminating Beam in an Absorbing Medium

NASA Astrophysics Data System (ADS)

Bubis, E. L.; Lozhrkarev, V. V.; Stepanov, A. N.; Smirnov, A. I.; Martynov, V. O.; Mal'shakova, O. A.; Silin, D. E.; Gusev, S. A.

2017-03-01

We describe the process of adaptive self-inversion of an image (nonlinear switching) of smallscale opaque object, when the amplitude-modulated laser beam, which illuminates it, is focused in a weakly absorbing medium. It is shown that, despite the nonlocal character of the process, which is due to thermal nonlinearity, the brightness-inverse image is characterized by acceptable quality and a high conversion coefficient. It is shown that the coefficient of conversion of the original image to the inverse one depends on the ratio of the object dimensions and the size of the illuminating beam, and decreases sharply for relatively large objects. The obtained experimental data agree with the numerical calculations. Inversion of the images of several model objects and microdefects in a nonlinear KDP crystal is demonstrated.

Analytical coupled modeling of a magneto-based acoustic metamaterial harvester

NASA Astrophysics Data System (ADS)

Nguyen, H.; Zhu, R.; Chen, J. K.; Tracy, S. L.; Huang, G. L.

2018-05-01

Membrane-type acoustic metamaterials (MAMs) have demonstrated unusual capacity in controlling low-frequency sound transmission, reflection, and absorption. In this paper, an analytical vibro-acoustic-electromagnetic coupling model is developed to study MAM harvester sound absorption, energy conversion, and energy harvesting behavior under a normal sound incidence. The MAM harvester is composed of a prestressed membrane with an attached rigid mass, a magnet coil, and a permanent magnet coin. To accurately capture finite-dimension rigid mass effects on the membrane deformation under the variable magnet force, a theoretical model based on the deviating acoustic surface Green’s function approach is developed by considering the acoustic near field and distributed effective shear force along the interfacial boundary between the mass and the membrane. The accuracy and capability of the theoretical model is verified through comparison with the finite element method. In particular, sound absorption, acoustic-electric energy conversion, and harvesting coefficient are quantitatively investigated by varying the weight and size of the attached mass, prestress and thickness of the membrane. It is found that the highest achievable conversion and harvesting coefficients can reach up to 48%, and 36%, respectively. The developed model can serve as an efficient tool for designing MAM harvesters.

Segregation of chlorine in n-type tin monosulfide ceramics: Actual chlorine concentration for carrier-type conversion

NASA Astrophysics Data System (ADS)

Iguchi, Yuki; Sugiyama, Taiki; Inoue, Kazutoshi; Yanagi, Hiroshi

2018-05-01

Tin monosulfide (SnS) is an attractive material for photovoltaic cells because of its suitable band-gap energy, high absorption coefficient, and non-toxic and abundant constituent elements. The primary drawback of this material is the lack of n-type SnS. We recently demonstrated n-type SnS by doping with Cl. However, the Cl-doped n-type SnS bulk ceramics exhibited an odd behavior in which carrier-type conversion but not electron carrier concentration depended on the Cl concentration. In this study, the electron probe microanalysis (EPMA) elemental mapping of Cl-doped SnS revealed continuous homogeneous regions with a relatively low Cl concentration along with the islands of high Cl concentration in which Sn/S is far from unity. The difference between the Cl concentration in the homogeneous region (determined by EPMA) and the bulk Cl concentration (determined by wavelength-dispersive X-ray fluorescence spectroscopy) increased with the increasing Cl doping amount. The carrier concentration and the Hall coefficient clearly depended on the Cl concentration in the homogeneous region. Carrier-type conversion was observed at the Cl concentration of 0.26 at. % (in the homogeneous region).

Transition Metal Carbides and Nitrides in Energy Storage and Conversion

PubMed Central

Zhong, Yu; Shi, Fan; Zhan, Jiye; Tu, Jiangping

2016-01-01

High‐performance electrode materials are the key to advances in the areas of energy conversion and storage (e.g., fuel cells and batteries). In this Review, recent progress in the synthesis and electrochemical application of transition metal carbides (TMCs) and nitrides (TMNs) for energy storage and conversion is summarized. Their electrochemical properties in Li‐ion and Na‐ion batteries as well as in supercapacitors, and electrocatalytic reactions (oxygen evolution and reduction reactions, and hydrogen evolution reaction) are discussed in association with their crystal structure/morphology/composition. Advantages and benefits of nanostructuring (e.g., 2D MXenes) are highlighted. Prospects of future research trends in rational design of high‐performance TMCs and TMNs electrodes are provided at the end. PMID:27812464

Enhancing the thermoelectric performance of gamma-graphyne nanoribbons by introducing edge disorder.

PubMed

Cui, Xiao; Ouyang, Tao; Li, Jin; He, Chaoyu; Tang, Chao; Zhong, Jianxin

2018-03-07

Structure disorder especially edge disorder is unavoidable during the fabrication of nanomaterials. In this paper, using the non-equilibrium Green's function method, we investigate the influence of edge disorder on the thermoelectric performance of gamma(γ)-graphyne nanoribbons (GYNRs). Our results show that the high Seebeck coefficient in pristine γ-GYNR could still be preserved although edge disorder is introduced into the structure. Meanwhile, in these edge-disordered nanoribbons the suppression of thermal conductance including electronic and phononic contributions outweighs the reduction of electronic conductance. These two positive effects combine together, and finally boost the thermoelectric conversion efficiency of γ-GYNRs. The thermoelectric figure of merit ZT in the edge-disordered γ-GYNRs (the length and width are about 55.68 and 1.41 nm) could approach 2.5 at room temperature, and can even reach as high as 4.0 at 700 K, which is comparable to the efficiency of conventional energy conversion methods. The findings in this paper indicate that the edge-disordered γ-GYNRs are a promising candidate for efficient thermoelectric energy conversion and thermal management of nanodevices.

Interexaminer reliability of the electromagnetic radiation receiver for determining lumbar spinal joint dysfunction in subjects with low back pain

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gemmell, H.A.; Jacobson, B.H.; Edwards, S.W.

Twenty subjects (6 male, 14 female) with low back pain were examined by two experienced and licensed chiropractic doctors (E1 and E2). Both examiners examined the patients using a Toftness Electromagnetic Radiation Receiver (EMRR) and by manual palpation (MP) of the spinous processes. Interexaminer reliability was calculated at three sites (L3, L4, L5) for the following combinations: (a) E1,MP--E2,MP; (b) E1,EMRR--E2,EMRR; (c) E1,MP--E2,EMRR; and (d) E2,MP--E1,EMRR, and intraexaminer reliability was calculated for the following variables: (e) E1,MP--E1,EMRR; and (f) E2,MP--E2,EMRR. Results of a Kappa coefficient analysis for interexaminer reliability of the stated combinations and at the specific sites were: (a)more » -0.071, 0.400, 0.200; (b) -0.013, 0.100, -0.120; (c) 0.286, 0.300, 0.200; (d) -0.081, 0.000, 0.048. These results predominantly indicate a poor to fair interexaminer reliability. The results of a Kappa coefficient analysis for intraexaminer reliability of the stated combinations were: (e) 0.111, 0.400, 0.737; (f) 0.000, 0.100, 0.368. These results indicate a poor to fair reliability. It was concluded that in subjects with low back pain the EMRR may not be a reliable indicator of spinal joint dysfunction.« less

Electrochemical Detection of Dopamine via Assisted Ion Transfer at Nanopipet Electrode Using Cyclic Voltammetry.

PubMed

Colombo, Michelle L; McNeil, Swami; Iwai, Nicholas; Chang, Albert; Shen, Mei

2016-01-01

We present here the detection of dopamine (DA) at nanopipet electrodes with radii of hundreds of nanometers ranging from 160 nm to 480 nm. Dibenzo-18-crown-6 (DB18C6) was employed as an ionophore to facilitate DA transfer, resulting in a half-wave transfer potential, E 1/2, DA , of -0.322 (±0.020) V vs. E 1/2, TBA . Well-defined steady-state sigmoidal cyclic voltammograms were observed for the transfer of DA. High resolution scanning electron microscopy was used to measure the size and taper angle of the nanopipet electrodes. The detection is linear with concentration of DA ranging from 0.25 mM to 2 mM; calculated diffusion coefficient at nanopipet electrodes with above mentioned sizes is 4.87 (±0.28) × 10 -10 m 2 /s. The effect of the common interferent ascorbic acid on DA detection with nanopipet electrodes was evaluated, where DA detection still shows linear behavior with well-defined sigmoidal CVs with E 1/2, DA being -0.328 (±0.029) V vs. E 1/2, TBA . The diffusion coefficient for DA transfer in MgCl 2 with the presence of 2 mM AA was measured to be 1.93 (±0.59) × 10 -10 m 2 /s on nanoelectrodes with radii from 161 nm to 263 nm, but the physiological concentration of 0.1 mM AA had no effect on DA's diffusion coefficient.

Improved conversion efficiency of dye sensitized solar cell using Zn doped TiO2-ZrO2 nanocomposite

NASA Astrophysics Data System (ADS)

Tomar, Laxmi J.; Bhatt, Piyush J.; Desai, Rahul K.; Chakrabarty, B. S.; Panchal, C. J.

2016-05-01

TiO2-ZrO2 and Zn doped TiO2-ZrO2 nanocomposites were prepared by hydrothermal method for dye sensitized solar cell (DSSC) application. The structural and optical properties were investigated by X -ray diffraction (XRD) and UV-Visible spectroscopy respectively. XRD results revealed the formation of material in nano size. The average crystallite size is 22.32 nm, 17.41 nm and 6.31 nm for TiO2, TiO2-ZrO2 and Zn doped TiO2-ZrO2 nanocomposites respectively. The optical bandgap varies from 2.04 eV to 3.75 eV. Dye sensitized solar cells were fabricated using the prepared material. Pomegranate juice was used as a sensitizer and graphite coated conducting glass plate was used as counter electrode. The I - V characteristics were recorded to measure photo response of DSSC. Photovoltaic parameter like open circuit voltage, power conversion efficiency, and fill factor were evaluated for fabricated solar cell. The power conversion efficiency of DSSC fabricated with TiO2, TiO2-ZrO2 and Zn doped TiO2-ZrO2 nanocomposites were found 0.71%, 1.97% and 4.58% respectively.

Pristine Metal-Organic Frameworks and their Composites for Energy Storage and Conversion.

PubMed

Liang, Zibin; Qu, Chong; Guo, Wenhan; Zou, Ruqiang; Xu, Qiang

2017-11-22

Metal-organic frameworks (MOFs), a new class of crystalline porous organic-inorganic hybrid materials, have recently attracted increasing interest in the field of energy storage and conversion. Herein, recent progress of MOFs and MOF composites for energy storage and conversion applications, including photochemical and electrochemical fuel production (hydrogen production and CO 2 reduction), water oxidation, supercapacitors, and Li-based batteries (Li-ion, Li-S, and Li-O 2 batteries), is summarized. Typical development strategies (e.g., incorporation of active components, design of smart morphologies, and judicious selection of organic linkers and metal nodes) of MOFs and MOF composites for particular energy storage and conversion applications are highlighted. A broad overview of recent progress is provided, which will hopefully promote the future development of MOFs and MOF composites for advanced energy storage and conversion applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An Alternative to the Breeder’s and Lande’s Equations

PubMed Central

Houchmandzadeh, Bahram

2013-01-01

The breeder’s equation is a cornerstone of quantitative genetics, widely used in evolutionary modeling. Noting the mean phenotype in parental, selected parents, and the progeny by E(Z0), E(ZW), and E(Z1), this equation relates response to selection R = E(Z1) − E(Z0) to the selection differential S = E(ZW) − E(Z0) through a simple proportionality relation R = h2S, where the heritability coefficient h2 is a simple function of genotype and environment factors variance. The validity of this relation relies strongly on the normal (Gaussian) distribution of the parent genotype, which is an unobservable quantity and cannot be ascertained. In contrast, we show here that if the fitness (or selection) function is Gaussian with mean μ, an alternative, exact linear equation of the form R′ = j2S′ can be derived, regardless of the parental genotype distribution. Here R′ = E(Z1) − μ and S′ = E(ZW) − μ stand for the mean phenotypic lag with respect to the mean of the fitness function in the offspring and selected populations. The proportionality coefficient j2 is a simple function of selection function and environment factors variance, but does not contain the genotype variance. To demonstrate this, we derive the exact functional relation between the mean phenotype in the selected and the offspring population and deduce all cases that lead to a linear relation between them. These results generalize naturally to the concept of G matrix and the multivariate Lande’s equation Δz¯=GP−1S. The linearity coefficient of the alternative equation are not changed by Gaussian selection. PMID:24212080

Carbon nanotube/polymer composite coated tapered fiber for four wave mixing based wavelength conversion.

PubMed

Xu, Bo; Omura, Mika; Takiguchi, Masato; Martinez, Amos; Ishigure, Takaaki; Yamashita, Shinji; Kuga, Takahiro

2013-02-11

In this paper, we demonstrate a nonlinear optical device based on a fiber taper coated with a carbon nanotube (CNT)/polymer composite. Using this device, four wave mixing (FWM) based wavelength conversion of 10 Gb/s Non-return-to-zero signal is achieved. In addition, we investigate wavelength tuning, two photon absorption and estimate the effective nonlinear coefficient of the CNTs embedded in the tapered fiber to be 1816.8 W(-1)km(-1).

NRL (Naval Research Laboratory) Plasma Formulary. Revised.

DTIC Science & Technology

1983-01-01

EQUATIONS Name Rationalized inks Gaussian Faday’s law V xE -- !-s VxE--l1p .aD -l3D 4i" Ampere’slta xH-VxH -- +J VxH -- .- +- J at C at C Poison’s eqution...energy density Froude Fr t V (gL ) 1/2 (Inertial forces/gravitational or VINL buoyancy forces) t/2 Gay- Lussac Ga I/PA T (Relative volume change...112 Alfvin speed a Newton’s- law heat coefficient, k x " aA T aix Volumetric expansion coefficient, dV/ V - )dT r Bulk modulus (units m/it 2 ) AR, A

NRL Plasma Formulary. Revision

DTIC Science & Technology

1990-01-01

Description SI Gaussian 9B 1l0B Faraday’s law V x E -- V x E =-- at c Ot c9D 10D 4wr Ampere’s law V x H + J V x H =- + -J at c Ot c Poisson equation V - D = p...Froude Fr V/(g L) 1/ 2 t(Inertial force/gravitational or V/NL buoyancy force) 1 /2 Gay- Lussac Ga 1/fOAT Inverse of relative change in volume during... law heat coefficient, k = crAT0ax Volumetric expansion coefficient, dV/V = )3dT Bulk modulus (units kg m 1 s - 2) 6R, AV, Ap, AT Imposed difference in

Analysis of the attainable efficiency of a direct-bandgap betavoltaic element

NASA Astrophysics Data System (ADS)

Sachenko, A. V.; Shkrebtii, A. I.; Korkishko, R. M.; Kostylyov, V. P.; Kulish, M. R.; Sokolovskyi, I. O.; Evstigneev, M.

2015-11-01

Conversion of energy of beta-particles into electric energy in a p-n junction based on direct-bandgap semiconductors, such as GaAs, is analyzed considering realistic semiconductor system parameters. An expression for the collection coefficient, Q, of the electron-hole pairs generated by beta-electrons is derived taking into account the existence of the dead layer. We show that the collection coefficient of beta-electrons emitted by a 3H-source to a GaAs p-n junction is close to 1 in a broad range of electron lifetimes in the junction, ranging from 10-9to 10-7 s. For the combination 147Pm/GaAs, Q is relatively large (≥slant 0.4) only for quite long lifetimes (about 10-7 s) and large thicknesses (about 100 μm) of GaAs p-n junctions. For realistic lifetimes of minority carriers and their diffusion coefficients, the open-circuit voltage realized due to the irradiation of a GaAs p-n junction by beta-particles is obtained. The attainable beta-conversion efficiency η in the case of a 3H/GaAs combination is found to exceed that of the 147Pm/GaAs combination.

Bidirectional sex change induced by sex steroid implantation in the hermaphrodite fish, Pseudolabrus sieboldi.

PubMed

Ohta, Kohei; Sakai, Mami; Sundaray, Jittendra Kumar; Kitano, Takeshi; Takeda, Tatsusuke; Yamaguchi, Akihiko; Matsuyama, Michiya

2012-11-01

Sex steroids have been suggested to be involved in gonadal sex change in hermaphrodite fish. Aromatase, the enzyme that catalyzes the conversion of androgens into estrogens, is a principal enzyme regulating gonadal sex. However, the detailed functions of each steroid hormone remain to be evaluated. Recent studies have demonstrated that estradiol-17β (E2) is synthesized via estrone (E1) in some hermaphrodite species. On the other hand, 11-ketotestosterone (11KT) is produced in the testis via testosterone (T). In this study, we hypothesized that E1 and T are also involved in the sex change as precursors for E2 and 11KT, respectively. We implanted females of the wrasse, Pseudolabrus sieboldi, with T and 11KT, and males with E1 and E2, by use of sustained-release capsules. In females, testicular tissues and body color change were observed after androgen administration, in which 11KT was more effective than T. In contrast, after estrogen administration, the gonads of males contained oocytes. In females, the administration of T and 11KT resulted in reduced serum E2 levels. Conversely, serum 11KT levels decreased in the E1- and E2-treated males. Thus, we successfully induced bidirectional sex change in the gonad by estrogen and androgen administration in vivo. Moreover, this study raises the possibility that E1 and T are involved in the sex change as precursors for E2 and 11KT, respectively. Copyright © 2012 Wiley Periodicals, Inc.

Effective diffusion coefficients of gas mixture in heavy oil under constant-pressure conditions

NASA Astrophysics Data System (ADS)

Li, Huazhou Andy; Sun, Huijuan; Yang, Daoyong

2017-05-01

We develop a method to determine the effective diffusion coefficient for each individual component of a gas mixture in a non-volatile liquid (e.g., heavy oil) at high pressures with compositional analysis. Theoretically, a multi-component one-way diffusion model is coupled with the volume-translated Peng-Robinson equation of state to quantify the mass transfer between gas and liquid (e.g., heavy oil). Experimentally, the diffusion tests have been conducted with a PVT setup for one pure CO2-heavy oil system and one C3H8-CO2-heavy oil system under constant temperature and pressure, respectively. Both the gas-phase volume and liquid-phase swelling effect are simultaneously recorded during the measurement. As for the C3H8-CO2-heavy oil system, the gas chromatography method is employed to measure compositions of the gas phase at the beginning and end of the diffusion measurement, respectively. The effective diffusion coefficients are then determined by minimizing the discrepancy between the measured and calculated gas-phase composition at the end of diffusion measurement. The newly developed technique can quantify the contributions of each component of mixture to the bulk mass transfer from gas into liquid. The effective diffusion coefficient of C3H8 in the C3H8-CO2 mixture at 3945 ± 20 kPa and 293.85 K, i.e., 18.19 × 10^{ - 10} {{m}}^{ 2} / {{s}}, is found to be much higher than CO2 at 3950 ± 18 kPa and 293.85 K, i.e., 8.68 × 10^{ - 10} {{m}}^{ 2} / {{s}}. In comparison with pure CO2, the presence of C3H8 in the C3H8-CO2 mixture contributes to a faster diffusion of CO2 from the gas phase into heavy oil and consequently a larger swelling factor of heavy oil.

Optical band gap and spectroscopic study of lithium alumino silicate glass containing Y 3+ ions

NASA Astrophysics Data System (ADS)

Shakeri, M. S.; Rezvani, M.

2011-09-01

The effect of different amounts of Y 2O 3 dopant on lithium alumino silicate (LAS) glass has been studied in this work. Glasses having 14.8Li 2O-20Al 2O 3-65.2SiO 2 (wt%) composition accompanied with Y 2O 3 dopant were prepared by normal melting process. In order to calculate the absorption coefficient of samples, transmittance and reflectance spectra of polished samples were measured in the room temperature. Optical properties i.e. Fermi energy level, direct and indirect optical band gaps and Urbach energy were calculated using functionality of extinction coefficient from Fermi-Dirac distribution function, Tauc's plot and the exponential part of absorption coefficient diagram, respectively. It has been clarified that variation in mentioned optical parameters is associated with the changes in physical properties of samples i.e. density or molar mass. On the other hand, increasing of Y 3+ ions in the glassy microstructure of samples provides a semiconducting character to LAS glass by reducing the direct and indirect optical band gaps of glass samples from 1.97 to 1.67 and 3.46 to 2.1 (eV), respectively. These changes could be attributed to the role of Y 3+ ions as the network former in the track of SiO 4 tetrahedrals.

Stromal cell-derived factor 2 is critical for Hsp90-dependent eNOS activation.

PubMed

Siragusa, Mauro; Fröhlich, Florian; Park, Eon Joo; Schleicher, Michael; Walther, Tobias C; Sessa, William C

2015-08-18

Endothelial nitric oxide synthase (eNOS) catalyzes the conversion of l-arginine and molecular oxygen into l-citrulline and nitric oxide (NO), a gaseous second messenger that influences cardiovascular physiology and disease. Several mechanisms regulate eNOS activity and function, including phosphorylation at Ser and Thr residues and protein-protein interactions. Combining a tandem affinity purification approach and mass spectrometry, we identified stromal cell-derived factor 2 (SDF2) as a component of the eNOS macromolecular complex in endothelial cells. SDF2 knockdown impaired agonist-stimulated NO synthesis and decreased the phosphorylation of eNOS at Ser(1177), a key event required for maximal activation of eNOS. Conversely, SDF2 overexpression dose-dependently increased NO synthesis through a mechanism involving Akt and calcium (induced with ionomycin), which increased the phosphorylation of Ser(1177) in eNOS. NO synthesis by iNOS (inducible NOS) and nNOS (neuronal NOS) was also enhanced upon SDF2 overexpression. We found that SDF2 was a client protein of the chaperone protein Hsp90, interacting preferentially with the M domain of Hsp90, which is the same domain that binds to eNOS. In endothelial cells exposed to vascular endothelial growth factor (VEGF), SDF2 was required for the binding of Hsp90 and calmodulin to eNOS, resulting in eNOS phosphorylation and activation. Thus, our data describe a function for SDF2 as a component of the Hsp90-eNOS complex that is critical for signal transduction in endothelial cells. Copyright © 2015, American Association for the Advancement of Science.

Stromal cell–derived factor 2 is critical for Hsp90-dependent eNOS activation

PubMed Central

Siragusa, Mauro; Fröhlich, Florian; Park, Eon Joo; Schleicher, Michael; Walther, Tobias C.; Sessa, William C.

2016-01-01

Endothelial nitric oxide synthase (eNOS) catalyzes the conversion of l-arginine and molecular oxygen into l-citrulline and nitric oxide (NO), a gaseous second messenger that influences cardiovascular physiology and disease. Several mechanisms regulate eNOS activity and function, including phosphorylation at Ser and Thr residues and protein-protein interactions. Combining a tandem affinity purification approach and mass spectrometry, we identified stromal cell–derived factor 2 (SDF2) as a component of the eNOS macromolecular complex in endothelial cells. SDF2 knockdown impaired agonist-stimulated NO synthesis and decreased the phosphorylation of eNOS at Ser1177, a key event required for maximal activation of eNOS. Conversely, SDF2 overexpression dose-dependently increased NO synthesis through a mechanism involving Akt and calcium (induced with ionomycin), which increased the phosphorylation of Ser1177 in eNOS. NO synthesis by iNOS (inducible NOS) and nNOS (neuronal NOS) was also enhanced upon SDF2 overexpression. We found that SDF2 was a client protein of the chaperone protein Hsp90, interacting preferentially with the M domain of Hsp90, which is the same domain that binds to eNOS. In endothelial cells exposed to vascular endothelial growth factor (VEGF), SDF2 was required for the binding of Hsp90 and calmodulin to eNOS, resulting in eNOS phosphorylation and activation. Thus, our data describe a function for SDF2 as a component of the Hsp90-eNOS complex that is critical for signal transduction in endothelial cells. PMID:26286023

Transfer having a coupling coefficient higher than its active material

NASA Technical Reports Server (NTRS)

Lesieutre, George A. (Inventor); Davis, Christopher L. (Inventor)

2001-01-01

A coupling coefficient is a measure of the effectiveness with which a shape-changing material (or a device employing such a material) converts the energy in an imposed signal to useful mechanical energy. Device coupling coefficients are properties of the device and, although related to the material coupling coefficients, are generally different from them. This invention describes a class of devices wherein the apparent coupling coefficient can, in principle, approach 1.0, corresponding to perfect electromechanical energy conversion. The key feature of this class of devices is the use of destabilizing mechanical pre-loads to counter inherent stiffness. The approach is illustrated for piezoelectric and thermoelectrically actuated devices. The invention provides a way to simultaneously increase both displacement and force, distinguishing it from alternatives such as motion amplification, and allows transducer designers to achieve substantial performance gains for actuator and sensor devices.

K-shell photoabsorption coefficients of O2, CO2, CO, and N2O

NASA Technical Reports Server (NTRS)

Barrus, D. M.; Blake, R. L.; Burek, A. J.; Chambers, K. C.; Pregenzer, A. L.

1979-01-01

The total photoabsorption coefficient has been measured from 500 to 600 eV around the K edge of oxygen in gases O2, CO2, CO, and N2O by means of a gold continuum source and crystal spectrometer with better than 1-eV resolution. The cross sections are dominated by discrete molecular-orbital transitions below the K-edge energy. A few Rydberg transitions were barely detectable. Broad shape resonances appear at or above the K edge. Additional broad, weak features above the K edge possibly arise from shake up. Quantitative results are given that have about 10% accuracy except on the very strong peaks. All the measured features are discussed in relation to other related measurements and theory.

Giant magnetoelectric effect in negative magnetostrictive/piezoelectric/positive magnetostrictive semiring structure

NASA Astrophysics Data System (ADS)

Zeng, Lingyu; Zhou, Minhong; Bi, Ke; Lei, Ming

2016-01-01

Magnetoelectric (ME) Ni/PZT/TbFe2 and TbFe2/PZT composites with two semiring structures are prepared. The dependence between ME coupling and magnetostrictive property of the composite is discussed. Because Ni possesses negative magnetostrictive property and TbFe2 shows positive magnetostrictive property, the ME voltage coefficient of Ni/PZT/TbFe2 semiring structure is much larger than that of TbFe2/PZT. In these composites, the ME voltage coefficient increases and the resonance frequency gradually decreases with the increase of the semiring radius, showing that structural parameters are key factors to the composite properties. Due to the strong ME coupling effect, a giant ME voltage coefficient αE = 44.8 V cm-1 Oe-1 is obtained. This approach opens a way for the design of ME composites with giant ME voltage coefficient.

Hierarchically Patterned Noncovalent Functionalization of 2D Materials by Controlled Langmuir-Schaefer Conversion.

PubMed

Davis, Tyson C; Bang, Jae Jin; Brooks, Jacob T; McMillan, David G; Claridge, Shelley A

2018-01-30

Noncovalent monolayer chemistries are often used to functionalize 2D materials. Nanoscopic ligand ordering has been widely demonstrated (e.g., lying-down lamellar phases of functional alkanes); however, combining this control with micro- and macroscopic patterning for practical applications remains a significant challenge. A few reports have demonstrated that standing phase Langmuir films on water can be converted into nanoscopic lying-down molecular domains on 2D substrates (e.g., graphite), using horizontal dipping (Langmuir-Schaefer, LS, transfer). Molecular patterns are known to form at scales up to millimeters in Langmuir films, suggesting the possibility of transforming such structures into functional patterns on 2D materials. However, to our knowledge, this approach has not been investigated, and the rules governing LS conversion are not well understood. In part, this is because the conversion process is mechanistically very different from classic LS transfer of standing phases; challenges also arise due to the need to characterize structure in noncovalently adsorbed ligand layers <0.5 nm thick, at scales ranging from millimeters to nanometers. Here, we show that scanning electron microscopy enables diynoic acid lying-down phases to be imaged across this range of scales; using this structural information, we establish conditions for LS conversion to create hierarchical microscopic and nanoscopic functional patterns. Such control opens the door to tailoring noncovalent surface chemistry of 2D materials to pattern local interactions with the environment.

Late conversion from tacrolimus to a belatacept-based immuno-suppression regime in kidney transplant recipients improves renal function, acid-base derangement and mineral-bone metabolism.

PubMed

Schulte, Kevin; Vollmer, Clara; Klasen, Vera; Bräsen, Jan Hinrich; Püchel, Jodok; Borzikowsky, Christoph; Kunzendorf, Ulrich; Feldkamp, Thorsten

2017-08-01

Calcineurin inhibitor (CNI)-induced nephrotoxicity and chronic graft dysfunction with deteriorating glomerular filtration rate (GFR) are common problems of kidney transplant recipients. The aim of this study was to analyze the role of belatacept as a rescue therapy in these patients. In this retrospective, observational study we investigated 20 patients (10 females, 10 males) who were switched from a CNI (tacrolimus) to a belatacept-based immunosuppression because of CNI intolerance or marginal transplant function. Patient follow-up was 12 months. Patients were converted to belatacept in mean 28.8 months after transplantation. Reasons for conversion were CNI intolerance (14 patients) or marginal transplant function (6 patients). Mean estimated GFR (eGFR) before conversion was 22.2 ± 9.4 ml/min at baseline and improved significantly to 28.3 ± 10.1 ml/min at 4 weeks and to 32.1 ± 12.6 ml/min at 12 months after conversion. Serum bicarbonate significantly increased from 24.4 ± 3.2 mmol/l at baseline to 28.7 ± 2.6 mmol/l after 12 months. Conversion to belatacept decreased parathyroid hormone and phosphate concentrations significantly, whereas albumin levels significantly increased. In 6 cases an acute rejection preceded clinically relevant CNI toxicity; only two patients suffered from an acute rejection after conversion. Belatacept was well tolerated and there was no increase in infectious or malignant side effects. A late conversion from a tacrolimus-based immunosuppression to belatacept is safe, effective and significantly improves renal function in kidney transplant recipients. Additionally, the conversion to belatacept has a beneficial impact on acid-base balance, mineral-bone and protein metabolism, independently of eGFR.

Catalytic conversion of lignin pyrolysis model compound- guaiacol and its kinetic model including coke formation.

PubMed

Zhang, Huiyan; Wang, Yun; Shao, Shanshan; Xiao, Rui

2016-11-21

Lignin is the most difficult to be converted and most easy coking component in biomass catalytic pyrolysis to high-value liquid fuels and chemicals. Catalytic conversion of guaiacol as a lignin model compound was conducted in a fixed-bed reactor over ZSM-5 to investigate its conversion and coking behaviors. The effects of temperature, weight hourly space velocity (WHSV) and partial pressure on product distribution were studied. The results show the maximum aromatic carbon yield of 28.55% was obtained at temperature of 650 °C, WHSV of 8 h -1 and partial pressure of 2.38 kPa, while the coke carbon yield was 19.55%. The reaction pathway was speculated to be removing methoxy group to form phenols with further aromatization to form aromatics. The amount of coke increased with increasing reaction time. The surface area and acidity of catalysts declined as coke formed on the acid sites and blocked the pore channels, which led to the decrease of aromatic yields. Finally, a kinetic model of guaiacol catalytic conversion considering coke deposition was built based on the above reaction pathway to properly predict product distribution. The experimental and model predicting data agreed well. The correlation coefficient of all equations were all higher than 0.90.

Catalytic conversion of lignin pyrolysis model compound- guaiacol and its kinetic model including coke formation

PubMed Central

Zhang, Huiyan; Wang, Yun; Shao, Shanshan; Xiao, Rui

2016-01-01

Lignin is the most difficult to be converted and most easy coking component in biomass catalytic pyrolysis to high-value liquid fuels and chemicals. Catalytic conversion of guaiacol as a lignin model compound was conducted in a fixed-bed reactor over ZSM-5 to investigate its conversion and coking behaviors. The effects of temperature, weight hourly space velocity (WHSV) and partial pressure on product distribution were studied. The results show the maximum aromatic carbon yield of 28.55% was obtained at temperature of 650 °C, WHSV of 8 h−1 and partial pressure of 2.38 kPa, while the coke carbon yield was 19.55%. The reaction pathway was speculated to be removing methoxy group to form phenols with further aromatization to form aromatics. The amount of coke increased with increasing reaction time. The surface area and acidity of catalysts declined as coke formed on the acid sites and blocked the pore channels, which led to the decrease of aromatic yields. Finally, a kinetic model of guaiacol catalytic conversion considering coke deposition was built based on the above reaction pathway to properly predict product distribution. The experimental and model predicting data agreed well. The correlation coefficient of all equations were all higher than 0.90. PMID:27869228

Software for Preprocessing Data From Rocket-Engine Tests

NASA Technical Reports Server (NTRS)

Cheng, Chiu-Fu

2003-01-01

Three computer programs have been written to preprocess digitized outputs of sensors during rocket-engine tests at Stennis Space Center (SSC). The programs apply exclusively to the SSC E test-stand complex and utilize the SSC file format. The programs are the following: (1) Engineering Units Generator (EUGEN) converts sensor-output-measurement data to engineering units. The inputs to EUGEN are raw binary test-data files, which include the voltage data, a list identifying the data channels, and time codes. EUGEN effects conversion by use of a file that contains calibration coefficients for each channel. (2) QUICKLOOK enables immediate viewing of a few selected channels of data, in contradistinction to viewing only after post-test processing (which can take 30 minutes to several hours depending on the number of channels and other test parameters) of data from all channels. QUICKLOOK converts the selected data into a form in which they can be plotted in engineering units by use of Winplot. (3) EUPLOT provides a quick means for looking at data files generated by EUGEN without the necessity of relying on the PVWAVE based plotting software.

The 2009 Version of the Aeroprediction Code: The AP09

DTIC Science & Technology

2008-01-01

WITH LONG BOATTAILS .................. 17 2.6 INCORPORATION OF BOUNDARY LAYER DISPLACEMENT EFFECTS ON BODY TAIL CONFIGURATIONS WITH LONG B O A T T A...9 5 DECREASE IN CN. DUE TO BOATTAIL ...................................................... 11 6 PRESSURE COEFFICIENT ON CONE CYLINDER (M.o...2.07, a = 0 °) ....... 12 7 PRESSURE COEFFICIENT ON CONE CYLINDER (M, = 2.0, a = 12’) O F FIG U R E 6

Portraits of Early Moral Sensibility in Two Children's Everyday Conversations

ERIC Educational Resources Information Center

Wright, Jennifer Cole; Bartsch, Karen

2008-01-01

Two children's conversations with adults were examined for reference to moral issues using transcripts of archived at-home family talk from the Child Language Data Exchange System (CHILDES) database (MacWhinney, 2000). Through target words (e.g., good, wrong, mean) in transcripts of two children between ages 2.5 and 5.0 years, 1,333 moral…

Cognitive and Conversational Strategies in the Expression of Ethnic Prejudice. Prepublication/Working Paper No. 2.

ERIC Educational Resources Information Center

van Dijk, Teun A.

In order to design a cognitive model of ethnic attitudes, an interdisciplinary project has analyzed strategies used in everyday conversation among majority members about minority groups, e.g., immigrant workers from Turkey and Morocco and people from Surinam. Data were collected through undirected interviews among people in an Amsterdam…

The Mu2e crystal calorimeter

DOE PAGES

Happacher, Fabio

2017-09-15

The Mu2e Experiment at Fermilab will search for coherent, neutrino-less conversion of negative muons into electrons in the field of an Aluminum nucleus, μ - + Al → e - +Al. Data collection start is planned for the end of 2021. The dynamics of such charged lepton flavour violating (CLFV) process is well modelled by a two-body decay, resulting in a mono-energetic electron with an energy slightly below the muon rest mass. If no events are observed in three years of running, Mu2e will set an upper limit on the ratio between the conversion and the capture rates R μe = μ - + A(Z,N) → e - +A(Z,N)/μ - + A(Z,N) → ν μ - +A(Z-1,N) more » of ≤ 6 ×10 -17 (@ 90% C.L.). This will improve the current limit of four order of magnitudes with respect to the previous best experiment. Mu2e complements and extends the current search for μ → e γ decay at MEG as well as the direct searches for new physics at the LHC . The observation of such CLFV process could be clear evidence for New Physics beyond the Standard Model. Given its sensitivity, Mu2e will be able to probe New Physics at a scale inaccessible to direct searches at either present or planned high energy colliders. To search for the muon conversion process, a very intense pulsed beam of negative muons (~ 10 10 μ/ sec) is stopped on an Aluminum target inside a very long solenoid where the detector is also located. The Mu2e detector is composed of a straw tube tracker and a CsI crystals electromagnetic calorimeter. An external veto for cosmic rays surrounds the detector solenoid. In 2016, Mu2e has passed the final approval stage from DOE and has started its construction phase. As a result, an overview of the physics motivations for Mu2e, the current status of the experiment and the required performances and design details of the calorimeter are presented.« less

The Mu2e crystal calorimeter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Happacher, Fabio

The Mu2e Experiment at Fermilab will search for coherent, neutrino-less conversion of negative muons into electrons in the field of an Aluminum nucleus, μ - + Al → e - +Al. Data collection start is planned for the end of 2021. The dynamics of such charged lepton flavour violating (CLFV) process is well modelled by a two-body decay, resulting in a mono-energetic electron with an energy slightly below the muon rest mass. If no events are observed in three years of running, Mu2e will set an upper limit on the ratio between the conversion and the capture rates R μe = μ - + A(Z,N) → e - +A(Z,N)/μ - + A(Z,N) → ν μ - +A(Z-1,N) more » of ≤ 6 ×10 -17 (@ 90% C.L.). This will improve the current limit of four order of magnitudes with respect to the previous best experiment. Mu2e complements and extends the current search for μ → e γ decay at MEG as well as the direct searches for new physics at the LHC . The observation of such CLFV process could be clear evidence for New Physics beyond the Standard Model. Given its sensitivity, Mu2e will be able to probe New Physics at a scale inaccessible to direct searches at either present or planned high energy colliders. To search for the muon conversion process, a very intense pulsed beam of negative muons (~ 10 10 μ/ sec) is stopped on an Aluminum target inside a very long solenoid where the detector is also located. The Mu2e detector is composed of a straw tube tracker and a CsI crystals electromagnetic calorimeter. An external veto for cosmic rays surrounds the detector solenoid. In 2016, Mu2e has passed the final approval stage from DOE and has started its construction phase. As a result, an overview of the physics motivations for Mu2e, the current status of the experiment and the required performances and design details of the calorimeter are presented.« less

Assessing human variability in kinetics for exposures to multiple environmental chemicals: a physiologically based pharmacokinetic modeling case study with dichloromethane, benzene, toluene, ethylbenzene, and m-xylene.

PubMed

Valcke, Mathieu; Haddad, Sami

2015-01-01

The objective of this study was to compare the magnitude of interindividual variability in internal dose for inhalation exposure to single versus multiple chemicals. Physiologically based pharmacokinetic models for adults (AD), neonates (NEO), toddlers (TODD), and pregnant women (PW) were used to simulate inhalation exposure to "low" (RfC-like) or "high" (AEGL-like) air concentrations of benzene (Bz) or dichloromethane (DCM), along with various levels of toluene alone or toluene with ethylbenzene and xylene. Monte Carlo simulations were performed and distributions of relevant internal dose metrics of either Bz or DCM were computed. Area under the blood concentration of parent compound versus time curve (AUC)-based variability in AD, TODD, and PW rose for Bz when concomitant "low" exposure to mixtures of increasing complexities occurred (coefficient of variation (CV) = 16-24%, vs. 12-15% for Bz alone), but remained unchanged considering DCM. Conversely, AUC-based CV in NEO fell (15 to 5% for Bz; 12 to 6% for DCM). Comparable trends were observed considering production of metabolites (AMET), except for NEO's CYP2E1-mediated metabolites of Bz, where an increased CV was observed (20 to 71%). For "high" exposure scenarios, Cmax-based variability of Bz and DCM remained unchanged in AD and PW, but decreased in NEO (CV= 11-16% to 2-6%) and TODD (CV= 12-13% to 7-9%). Conversely, AMET-based variability for both substrates rose in every subpopulation. This study analyzed for the first time the impact of multiple exposures on interindividual variability in toxicokinetics. Evidence indicates that this impact depends upon chemical concentrations and biochemical properties, as well as the subpopulation and internal dose metrics considered.

On the size and temperature dependence of the energy gap in cadmium-selenide quantum dots embedded in fluorophosphate glasses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lipatova, Zh. O., E-mail: zluka-yo@mail.ru; Kolobkova, E. V.; Babkina, A. N.

2017-03-15

The temperature and size dependences of the energy gap in CdSe quantum dots with diameters of 2.4, 4.0, and 5.2 nm embedded in fluorophosphate glasses are investigated. It is shown that the temperature coefficient of the band gap dE{sub g}/dT in the quantum dots differs from the bulk value and depends strictly on the dot size. It is found that, furthermore, the energy of each transition in these quantum dots is characterized by an individual temperature coefficient dE/dT.

Quench protection analysis of the Mu2e production solenoid

NASA Astrophysics Data System (ADS)

Kashikhin, Vadim; Ambrosio, Giorgio; Andreev, Nikolai; Lamm, Michael; Nicol, Thomas; Orris, Darryl; Page, Thomas

2014-01-01

The Muon-to-Electron conversion experiment (Mu2e), under development at Fermilab, seeks to detect direct muon to electron conversion to provide evidence for a process violating muon and electron lepton number conservation that cannot be explained by the Standard Model of particle physics. The Mu2e magnet system consists of three large superconducting solenoids. In case of a quench, the stored magnetic energy is extracted to an external dump circuit. However, because of the fast current decay, a significant fraction of the energy dissipates inside of the cryostat in the coil support shells made of structural aluminum, and in the radiation shield. A 3D finite-element model of the complete cold-mass was created in order to simulate the quench development and understand the role of the quench-back. The simulation results are reported at the normal and non-standard operating conditions.

Quench protection analysis of the Mu2e production solenoid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kashikhin, Vadim; Ambrosio, Giorgio; Andreev, Nikolai

The Muon-to-Electron conversion experiment (Mu2e), under development at Fermilab, seeks to detect direct muon to electron conversion to provide evidence for a process violating muon and electron lepton number conservation that cannot be explained by the Standard Model of particle physics. The Mu2e magnet system consists of three large superconducting solenoids. In case of a quench, the stored magnetic energy is extracted to an external dump circuit. However, because of the fast current decay, a significant fraction of the energy dissipates inside of the cryostat in the coil support shells made of structural aluminum, and in the radiation shield. Amore » 3D finite-element model of the complete cold-mass was created in order to simulate the quench development and understand the role of the quench-back. The simulation results are reported at the normal and non-standard operating conditions.« less

Graphene for thermoelectronic solar energy conversion

NASA Astrophysics Data System (ADS)

De, Dilip K.; Olukunle, Olawole C.

2017-08-01

Graphene is a high temperature material which can stand temperature as high as 4600 K in vacuum. Even though its work function is high (4.6 eV) the thermionic emission current density at such temperature is very high. Graphene is a wonderful material whose work function can be engineered as desired. Kwon et al41 reported a chemical approach to reduce work function of graphene using K2CO3, Li2CO3, Rb2CO3, Cs2CO3. The work functions are reported to be 3.7 eV, 3.8 eV, 3.5 eV and 3.4 eV. Even though they did not report the high temperature tolerance of such alkali metal carbonate doped graphene, their works open a great promise for use of pure graphene and doped graphene as emitter (cathode) and collector (anode) in a solar thermionic energy converter. This paper discusses the dynamics of solar energy conversion to electrical energy using thermionic energy converter with graphene as emitter and collector. We have considered parabolic mirror concentrator to focus solar energy onto the emitter to achieve temperature around 4300 K. Our theoretical calculations and the modelling show that efficiency as high as 55% can easily be achieved if space-charge problem can be reduced and the collector can be cooled to certain proper temperature. We have discussed methods of controlling the associated space-charge problems. Richardson-Dushman equation modified by the authors have been used in this modelling. Such solar energy conversion would reduce the dependence on silicon solar panel and has great potential for future applications.

Edge union of networks on the same vertex set

NASA Astrophysics Data System (ADS)

Loe, Chuan Wen; Jeldtoft Jensen, Henrik

2013-06-01

Random network generators such as Erdős-Rényi, Watts-Strogatz and Barabási-Albert models are used as models to study real-world networks. Let G1(V, E1) and G2(V, E2) be two such networks on the same vertex set V. This paper studies the degree distribution and clustering coefficient of the resultant networks, G(V, E1∪E2).

A Practically Validated Intelligent Calibration Circuit Using Optimized ANN for Flow Measurement by Venturi

NASA Astrophysics Data System (ADS)

Venkata, Santhosh Krishnan; Roy, Binoy Krishna

2016-03-01

Design of an intelligent flow measurement technique using venturi flow meter is reported in this paper. The objectives of the present work are: (1) to extend the linearity range of measurement to 100 % of full scale input range, (2) to make the measurement technique adaptive to variations in discharge coefficient, diameter ratio of venturi nozzle and pipe (β), liquid density, and liquid temperature, and (3) to achieve the objectives (1) and (2) using an optimized neural network. The output of venturi flow meter is differential pressure. It is converted to voltage by using a suitable data conversion unit. A suitable optimized artificial neural network (ANN) is added, in place of conventional calibration circuit. ANN is trained, tested with simulated data considering variations in discharge coefficient, diameter ratio between venturi nozzle and pipe, liquid density, and liquid temperature. The proposed technique is then subjected to practical data for validation. Results show that the proposed technique has fulfilled the objectives.

Impact of hydrogen dilution on optical properties of intrinsic hydrogenated amorphous silicon films prepared by high density plasma chemical vapor deposition for solar cell applications

NASA Astrophysics Data System (ADS)

Chen, Huai-Yi; Lee, Yao-Jen; Chang, Chien-Pin; Koo, Horng-Show; Lai, Chiung-Hui

2013-01-01

P-i-n single-junction hydrogenated amorphous silicon (a-Si:H) thin film solar cells were successfully fabricated in this study on a glass substrate by high density plasma chemical vapor deposition (HDP-CVD) at low power of 50 W, low temperature of 200°C and various hydrogen dilution ratios (R). The open circuit voltage (Voc ), short circuit current density (Jsc ), fill factor (FF) and conversion efficiency (η) of the solar cell as well as the refractive index (n) and absorption coefficient (α) of the i-layer at 600 nm wavelength rise with increasing R until an abrupt drop at high hydrogen dilution, i.e. R > 0.95. However, the optical energy bandgap (Eg ) of the i-layer decreases with the R increase. Voc and α are inversely correlated with Eg . The hydrogen content affects the i-layer and p/i interface quality of the a-Si:H thin film solar cell with an optimal value of R = 0.95, which corresponds to solar cell conversion efficiency of 3.85%. The proposed a-Si:H thin film solar cell is expected to be improved in performance.

Estimation of transport parameters of phenolic compounds and inorganic contaminants through composite landfill liners using one-dimensional mass transport model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Varank, Gamze, E-mail: gvarank@yildiz.edu.tr; Demir, Ahmet, E-mail: ahmetd@yildiz.edu.tr; Yetilmezsoy, Kaan, E-mail: yetilmez@yildiz.edu.tr

2011-11-15

Highlights: > We conduct 1D advection-dispersion modeling to estimate transport parameters. > We examine fourteen phenolic compounds and three inorganic contaminants. > 2-MP, 2,4-DCP, 2,6-DCP, 2,4,5-TCP, 2,3,4,6-TeCP have the highest coefficients. > Dispersion coefficients of Cu are determined to be higher than Zn and Fe. > Transport of phenolics can be prevented by zeolite and bentonite in landfill liners. - Abstract: One-dimensional (1D) advection-dispersion transport modeling was conducted as a conceptual approach for the estimation of the transport parameters of fourteen different phenolic compounds (phenol, 2-CP, 2-MP, 3-MP, 4-MP, 2-NP, 4-NP, 2,4-DNP, 2,4-DCP, 2,6-DCP, 2,4,5-TCP, 2,4,6-TCP, 2,3,4,6-TeCP, PCP) and threemore » different inorganic contaminants (Cu, Zn, Fe) migrating downward through the several liner systems. Four identical pilot-scale landfill reactors (0.25 m{sup 3}) with different composite liners (R1: 0.10 + 0.10 m of compacted clay liner (CCL), L{sub e} = 0.20 m, k{sub e} = 1 x 10{sup -8} m/s, R2: 0.002-m-thick damaged high-density polyethylene (HDPE) geomembrane overlying 0.10 + 0.10 m of CCL, L{sub e} = 0.20 m, k{sub e} = 1 x 10{sup -8} m/s, R3: 0.002-m-thick damaged HDPE geomembrane overlying a 0.02-m-thick bentonite layer encapsulated between 0.10 + 0.10 m CCL, L{sub e} = 0.22 m, k{sub e} = 1 x 10{sup -8} m/s, R4: 0.002-m-thick damaged HDPE geomembrane overlying a 0.02-m-thick zeolite layer encapsulated between 0.10 + 0.10 m CCL, L{sub e} = 0.22 m, k{sub e} = 4.24 x 10{sup -7} m/s) were simultaneously run for a period of about 540 days to investigate the nature of diffusive and advective transport of the selected organic and inorganic contaminants. The results of 1D transport model showed that the highest molecular diffusion coefficients, ranging from 4.77 x 10{sup -10} to 10.67 x 10{sup -10} m{sup 2}/s, were estimated for phenol (R4), 2-MP (R1), 2,4-DNP (R2), 2,4-DCP (R1), 2,6-DCP (R2), 2,4,5-TCP (R2) and 2,3,4,6-TeCP (R1). For all reactors, dispersion coefficients of Cu, ranging from 3.47 x 10{sup -6} m{sup 2}/s to 5.37 x 10{sup -2} m{sup 2}/s, was determined to be higher than others obtained for Zn and Fe. Average molecular diffusion coefficients of phenolic compounds were estimated to be about 5.64 x 10{sup -10} m{sup 2}/s, 5.37 x 10{sup -10} m{sup 2}/s, 2.69 x 10{sup -10} m{sup 2}/s and 3.29 x 10{sup -10} m{sup 2}/s for R1, R2, R3 and R4 systems, respectively. The findings of this study clearly indicated that about 35-50% of transport of phenolic compounds to the groundwater is believed to be prevented with the use of zeolite and bentonite materials in landfill liner systems.« less

Transport properties of nonelectrolyte liquid mixtures—I. Viscosity coefficients for n-alkane mixtures at saturation pressure from 283 to 378 K

NASA Astrophysics Data System (ADS)

Dymond, J. H.; Young, K. J.

1980-12-01

Viscosity coefficient measurements at saturation pressure are reported for n-hexane + n-hexadecane, n-hexane + n-octane + n-hexadecane, and n-hexane + n-octane + n-dodecane + n-hexadecane at temperatures from 283 to 378 K. The results show that the Congruence Principle applies to the molar excess Gibbs free energy of activation for flow, δ* G E, at temperatures other than 298 K. However, curves of δ* G E versus index number of the mixture are temperature dependent, and this must be taken into account for accurate prediction of mixture viscosity coefficients by this approach. The purely empirical equation of Grunberg and Nissan; 1 10765_2004_Article_BF00516562_TeX2GIFE1.gif ln η = x_1 ln η _1 + x_2 ln η _2 + x_1 x_2 G which has the advantage of not involving molar volumes, satisfactorily reproduces the experimental results for the binary mixture, but G is definitely composition dependent.

Rate Coefficient Measurements of the Reaction CH3 + O2 = CH3O + O

NASA Technical Reports Server (NTRS)

Hwang, S. M.; Ryu, Si-Ok; DeWitt, K. J.; Rabinowitz, M. J.

1999-01-01

Rate coefficients for the reaction CH3 + O2 = CH3O + O were measured behind reflected shock waves in a series of lean CH4-O2-Ar mixtures using hydroxyl and methyl radical diagnostics. The rate coefficients are well represented by an Arrhenius expression given as k = (1.60(sup +0.67, sub -0.47 ) x 10(exp 13) e(-15813 +/- 587 K/T)/cubic cm.mol.s. This expression, which is valid in the temperature range 1575-1822 K, supports the downward trend in the rate coefficients that has been reported in recent determinations. All measurements to date, including the present study, have been to some extent affected by secondary reactions. The complications due to secondary reactions, choice of thermochemical data, and shock-boundary layer interactions that affect the determination of the rate coefficients are examined.

Ellipsometry study of optical parameters of AgIn5S8 crystals

NASA Astrophysics Data System (ADS)

Isik, Mehmet; Gasanly, Nizami

2015-12-01

AgIn5S8 crystals grown by Bridgman method were characterized for optical properties by ellipsometry measurements. Spectral dependence of optical parameters; real and imaginary parts of the pseudodielectric function, pseudorefractive index, pseudoextinction coefficient, reflectivity and absorption coefficient were obtained from ellipsometry experiments carried out in the 1.2-6.2 eV range. Direct band gap energy of 1.84 eV was found from the analysis of absorption coefficient vs. photon energy. The oscillator energy, dispersion energy and zero-frequency refractive index, high-frequency dielectric constant values were found from the analysis of the experimental data using Wemple-DiDomenico and Spitzer-Fan models. Crystal structure and atomic composition ratio of the constituent elements in the AgIn5S8 crystal were revealed from structural characterization techniques of X-ray diffraction and energy dispersive spectroscopy.

High lactic acid and fructose production via Mn2+-mediated conversion of inulin by Lactobacillus paracasei.

PubMed

Petrov, Kaloyan; Popova, Luiza; Petrova, Penka

2017-06-01

Lactobacillus paracasei DSM 23505 is able to produce high amounts of lactic acid (LA) by simultaneous saccharification and fermentation (SSF) of inulin. Aiming to obtain the highest possible amounts of LA and fructose, the present study is devoted to evaluate the impact of bivalent metal ions on the process of inulin conversion. It was shown that Mn 2+ strongly increases the activity of the purified key enzyme β-fructosidase. In vivo, batch fermentation kinetics revealed that the high Mn 2+ concentrations accelerated inulin hydrolysis by raise of the inulinase activity, and increased sugars conversion to LA through enhancement of the whole glycolytic flux. The highest LA concentration and yield were reached by addition of 15 mM Mn 2+ -151 g/L (corresponding to 40% increase) and 0.83 g/g, respectively. However, the relative quantification by real-time reverse transcription assay showed that the presence of Mn 2+ decreases the expression levels of fosE gene encoding β-fructosidase. Contrariwise, the full exclusion of metal ions resulted in fosE gene expression enhancement, blocked fructose transport, and hindered fructose conversion thus leading to huge fructose accumulation. During fed-batch with optimized medium and fermentation parameters, the fructose content reached 35.9% (w/v), achieving yield of 467 g fructose from 675 g inulin containing chicory flour powder (0.69 g/g). LA received in course of the batch fermentation and fructose gained by the fed-batch are the highest amounts ever obtained from inulin, thus disclosing the key role of Mn 2+ as a powerful tool to guide inulin conversion to targeted bio-chemicals.

Identification and Characterization of (3Z):(2E)-Hexenal Isomerases from Cucumber

PubMed Central

Spyropoulou, Eleni A.; Dekker, Henk L.; Steemers, Luuk; van Maarseveen, Jan H.; de Koster, Chris G.; Haring, Michel A.; Schuurink, Robert C.; Allmann, Silke

2017-01-01

E-2-hexenal is a volatile compound that is commonly emitted by wounded or stressed plants. It belongs to the group of so-called green leaf volatiles (GLVs), which play an important role in transferring information to plants and insects. While most biosynthetic enzymes upstream of E-2-hexenal have been studied extensively, much less is known about the enzyme responsible for the conversion from Z-3- to E-2-hexenal. In this study we have identified two (3Z):(2E)-hexenal isomerases (HIs) from cucumber fruits by classical biochemical fractionation techniques and we were able to confirm their activity by heterologous expression. Recombinant protein of the HIs did not only convert the leaf aldehyde Z-3-hexenal to E-2-hexenal, but also (Z,Z)-3,6-nonadienal to (E,Z)-2,6-nonadienal, these last two representing major flavor volatiles of cucumber fruits. Transient expression of the cucumber HIs in Nicotiana benthamiana leaves drastically changed the GLV bouquet of damaged plants from a Z-3- to an E-2-enriched GLV profile. Furthermore, transcriptional analysis revealed that the two HIs showed distinct expression patterns. While HI-1 was specifically expressed in the flesh of cucumber fruits HI-2 was expressed in leaves as well. Interestingly, wounding of cucumber leaves caused only a slight increase in HI-2 transcript levels. These results demonstrate that cucumber HIs are responsible for the rearrangement of Z-3-aldehydes in both leaves and fruits. Future research will reveal the physiological importance of an increased conversion to E-2-aldehydes for plants and insects. PMID:28824678

Identification and Characterization of (3Z):(2E)-Hexenal Isomerases from Cucumber.

PubMed

Spyropoulou, Eleni A; Dekker, Henk L; Steemers, Luuk; van Maarseveen, Jan H; de Koster, Chris G; Haring, Michel A; Schuurink, Robert C; Allmann, Silke

2017-01-01

E -2-hexenal is a volatile compound that is commonly emitted by wounded or stressed plants. It belongs to the group of so-called green leaf volatiles (GLVs), which play an important role in transferring information to plants and insects. While most biosynthetic enzymes upstream of E -2-hexenal have been studied extensively, much less is known about the enzyme responsible for the conversion from Z -3- to E -2-hexenal. In this study we have identified two (3 Z ):(2 E )-hexenal isomerases (HIs) from cucumber fruits by classical biochemical fractionation techniques and we were able to confirm their activity by heterologous expression. Recombinant protein of the HIs did not only convert the leaf aldehyde Z -3-hexenal to E -2-hexenal, but also ( Z,Z )-3,6-nonadienal to ( E,Z )-2,6-nonadienal, these last two representing major flavor volatiles of cucumber fruits. Transient expression of the cucumber HIs in Nicotiana benthamiana leaves drastically changed the GLV bouquet of damaged plants from a Z -3- to an E -2-enriched GLV profile. Furthermore, transcriptional analysis revealed that the two HIs showed distinct expression patterns. While HI-1 was specifically expressed in the flesh of cucumber fruits HI-2 was expressed in leaves as well. Interestingly, wounding of cucumber leaves caused only a slight increase in HI-2 transcript levels. These results demonstrate that cucumber HIs are responsible for the rearrangement of Z -3-aldehydes in both leaves and fruits. Future research will reveal the physiological importance of an increased conversion to E -2-aldehydes for plants and insects.

Conversion of para and ortho hydrogen in the Jovian planets

NASA Technical Reports Server (NTRS)

Massie, S. T.; Hunten, D. M.

1982-01-01

A mechanism is proposed which partially equilibrates the para and ortho rotational levels of molecular hydrogen in the atmospheres of Jupiter, Saturn, and Uranus. Catalytic reactions between the free-radical surface sites of aerosol particles and hydrogen modecules yield significant equilibration near 1 bar pressure, if the efficiency of conversion per collision is between 10 to the -8th and 10 to the -10th and the effective eddy mixing coefficient is 10,000 sq cm/sec. At lower pressures the ortho-para ratio retains the value at the top of the cloud layer, except for a very small effect from conversion in the thermosphere. The influence of conversion on the specific heat and adiabatic lapse rate is also investigated. The effect is found to be generally small, though is can rise to 10% inside the aerosol layer.

RESEARCH INVESTIGATIONS ON THE PROTEOME: 1. MECHANISMS OF REGULATING PROTEIN SYNTHESIS, AND 2. GLOBAL CHARACTERIZATION OF PROTEOMIC RESPONSES TO ARSENIC EXPOSURES

EPA Science Inventory

Eukaryotic Elongation Factor 2 (eEF2) mediates translocation in protein synthesis. eEF2 is modified by two post-translational modifications: the phosphorylation of Thr57 in the G domain and a unique conversion of His699 to diphthamide at the tip of domain IV. Diphthamide is the t...

Enhancement of convective heat transfer coefficient of ethylene glycol base cuprous oxide (Cu2O) nanofluids

NASA Astrophysics Data System (ADS)

Hassan, Ali; Ramzan, Naveed; Umer, Asim; Ahmad, Ayyaz; Muryam, Hina

2018-02-01

The enhancement in the convective heat transfer coefficient of the ethylene glycol (EG) base cuprous oxide (Cu2O) nanofluids were investigated. The nanofluids of different volume concentrations i-e 1%, 2.5% and 4.5% were prepared by the two step method. Cuprous oxide (Cu2O) nanoparticles were ultrasonically stirred for four hours in the ethylene glycol (EG). The experimental study has been performed through circular tube geometry in laminar flow regime at average Reynolds numbers 36, 71 and 116. The constant heat flux Q = 4000 (W/m2) was maintained during this work. Substantial enhancement was observed in the convective heat transfer coefficient of ethylene glycol (EG) base cuprous oxide (Cu2O) nanofluids than the base fluid. The maximum 74% enhancement was observed in convective heat transfer coefficient at 4.5 vol% concentration and Re = 116.

Comparison of two different physical activity monitors.

PubMed

Paul, David R; Kramer, Matthew; Moshfegh, Alanna J; Baer, David J; Rumpler, William V

2007-06-25

Understanding the relationships between physical activity (PA) and disease has become a major area of research interest. Activity monitors, devices that quantify free-living PA for prolonged periods of time (days or weeks), are increasingly being used to estimate PA. A range of different activity monitors brands are available for investigators to use, but little is known about how they respond to different levels of PA in the field, nor if data conversion between brands is possible. 56 women and men were fitted with two different activity monitors, the Actigraph (Actigraph LLC; AGR) and the Actical (Mini-Mitter Co.; MM) for 15 days. Both activity monitors were fixed to an elasticized belt worn over the hip, with the anterior and posterior position of the activity monitors randomized. Differences between activity monitors and the validity of brand inter-conversion were measured by t-tests, Pearson correlations, Bland-Altman plots, and coefficients of variation (CV). The AGR detected a significantly greater amount of daily PA (216.2 +/- 106.2 vs. 188.0 +/- 101.1 counts/min, P < 0.0001). The average difference between activity monitors expressed as a CV were 3.1 and 15.5% for log-transformed and raw data, respectively. When a conversion equation was applied to convert datasets from one brand to another, the differences were no longer significant, with CV's of 2.2 and 11.7%, log-transformed and raw data, respectively. Although activity monitors predict PA on the same scale (counts/min), the results between these two brands are not directly comparable. However, the data are comparable if a conversion equation is applied, with better results for log-transformed data.

Unbiased Sunlight-Driven Artificial Photosynthesis of Carbon Monoxide from CO2 Using a ZnTe-Based Photocathode and a Perovskite Solar Cell in Tandem.

PubMed

Jang, Youn Jeong; Jeong, Inyoung; Lee, Jaehyuk; Lee, Jinwoo; Ko, Min Jae; Lee, Jae Sung

2016-07-26

Solar fuel production, mimicking natural photosynthesis of converting CO2 into useful fuels and storing solar energy as chemical energy, has received great attention in recent years. Practical large-scale fuel production needs a unique device capable of CO2 reduction using only solar energy and water as an electron source. Here we report such a system composed of a gold-decorated triple-layered ZnO@ZnTe@CdTe core-shell nanorod array photocathode and a CH3NH3PbI3 perovskite solar cell in tandem. The assembly allows effective light harvesting of higher energy photons (>2.14 eV) from the front-side photocathode and lower energy photons (>1.5 eV) from the back-side-positioned perovskite solar cell in a single-photon excitation. This system represents an example of a photocathode-photovoltaic tandem device operating under sunlight without external bias for selective CO2 conversion. It exhibited a steady solar-to-CO conversion efficiency over 0.35% and a solar-to-fuel conversion efficiency exceeding 0.43% including H2 as a minor product.

On the relation between the activation energy for electron attachment reactions and the size of their thermal rate coefficients.

PubMed

Hotop, H; Ruf, M-W; Kopyra, J; Miller, T M; Fabrikant, I I

2011-02-14

Rate coefficients k(T) for dissociative electron attachment (DEA) to molecules in many cases exhibit a more or less strong rise with increasing temperature T (the electron temperature T(e) and the molecular temperature T(G) are assumed to be in thermal equilibrium, i.e., T = T(e) = T(G)). This rise is frequently modeled by the Arrhenius equation k(T) = k(A) exp[-E(a)∕(k(B)T)], and an activation energy E(a) is deduced from fits to the experimental data k(T). This behavior reflects the presence of an energy barrier for the anion on its path to the dissociated products. In a recent paper [J. Kopyra, J. Wnorowska, M. Foryś, and I. Szamrej, Int. J. Mass Spectrom. 268, 60 (2007)] it was suggested that the size of the rate coefficients for DEA reactions at room temperature exhibits an exponential dependence on the activation energy, i.e., k(E(a); T ≈ 300 K) = k(1) exp[-E(a)∕E(0)]. More recent experimental data for molecules with high barriers [T. M. Miller, J. F. Friedman, L. C. Schaffer, and A. A. Viggiano, J. Chem. Phys. 131, 084302 (2009)] are compatible with such a correlation. We investigate the validity and the possible origin of this dependence by analyzing the results of R-matrix calculations for temperature-dependent rate coefficients of exothermic DEA processes with intermediate barrier toward dissociation. These include results for model systems with systematically varied barrier height as well as results of molecule-specific calculations for CH(3)Cl, CH(3)Br, CF(3)Cl, and CH(2)Cl(2) (activation energies above 0.2 eV) involving appropriate molecular parameters. A comparison of the experimental and theoretical results for the considered class of molecules (halogenated alkanes) supports the idea that the exponential dependence of k(T = 300 K) on the activation energy reflects a general phenomenon associated with Franck-Condon factors for getting from the initial neutral vibrational levels to the dissociating final anion state in a direct DEA process. Cases are discussed for which the proposed relation does not apply.

Kinetics and product identification of the reactions of (E)-2-hexenyl acetate and 4-methyl-3-penten-2-one with OH radicals and Cl atoms at 298 K and atmospheric pressure

NASA Astrophysics Data System (ADS)

Gaona-Colmán, Elizabeth; Blanco, María B.; Teruel, Mariano A.

2017-07-01

Rate coefficients for the reactions of hydroxyl radicals and chlorine atoms with two biogenic volatile organic compounds as (E)-2-hexenyl acetate and 4-methyl-3-penten-2-one have been determined at 298 K and atmospheric pressure. The decay of the organics was followed using a chromatograph with a flame ionization detector (GC-FID) and the rate constants were determined using a relative rate method. Rate coefficients are found to be (in cm3 molecule-1 s-1): k1(OH + (E)-2-hexenyl acetate) = (6.88 ± 1.41) × 10-11, k2(Cl + (E)-2-hexenyl acetate) = (3.10 ± 1.13) × 10-10, k3(OH + 4-methyl-3-penten-2-one) = (1.02 ± 0.20) × 10-10 and k4(Cl + 4-methyl-3-penten-2-one) = (2.66 ± 0.90) × 10-10 at 298 K. This is the first kinetic experimental study for these reactions studied under atmospheric pressure. The rate coefficients are compared with previous determinations for other unsaturated and oxygenated compounds and reactivity trends are presented. Products identification studies were performed using solid-phase microextraction (SPME) method employing on-fiber products derivatization with o-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine hydrochloride using gas chromatograph with a mass spectrometer detector (GC-MS) for the reactions studied. In addition, atmospheric lifetimes of the unsaturated compounds studied are estimated and compared with other tropospheric sinks for these compounds.

Publications of the Division of Mechanical Engineering and the National Aeronautical Establishment. Series Number 2, Supplement Number 7.

DTIC Science & Technology

1982-01-01

1980 The Use of Heat Pipes to Control Temperature in Electronic Systems. B. Larkin, Gas Dynamics Laboratory. No. 3 - Apr. 1980 Industrial Combustor...1979. A SIMPLE LEAK-PROOF HEAT EXCHANGER FOR USE IN SOLAR ENERGY SYSTEMS, by B.S. Larkin and J. Ramsden. 14th Intersociety Energy Conversion Eng. Conf...STUDY OF THE TEMPERATURE PROFILES AND HEAT TRANSFER COEFFICIENTS IN A HEAT PIPE FOR A HEAT EXCHANGER, by B.S. Larkin. To be presented at 4th Int. Heat

Graded bandgap perovskite solar cells.

PubMed

Ergen, Onur; Gilbert, S Matt; Pham, Thang; Turner, Sally J; Tan, Mark Tian Zhi; Worsley, Marcus A; Zettl, Alex

2017-05-01

Organic-inorganic halide perovskite materials have emerged as attractive alternatives to conventional solar cell building blocks. Their high light absorption coefficients and long diffusion lengths suggest high power conversion efficiencies, and indeed perovskite-based single bandgap and tandem solar cell designs have yielded impressive performances. One approach to further enhance solar spectrum utilization is the graded bandgap, but this has not been previously achieved for perovskites. In this study, we demonstrate graded bandgap perovskite solar cells with steady-state conversion efficiencies averaging 18.4%, with a best of 21.7%, all without reflective coatings. An analysis of the experimental data yields high fill factors of ∼75% and high short-circuit current densities up to 42.1 mA cm -2 . The cells are based on an architecture of two perovskite layers (CH 3 NH 3 SnI 3 and CH 3 NH 3 PbI 3-x Br x ), incorporating GaN, monolayer hexagonal boron nitride, and graphene aerogel.

Surface reaction rate and probability of ozone and alpha-terpineol on glass, polyvinyl chloride, and latex paint surfaces.

PubMed

Shu, Shi; Morrison, Glenn C

2011-05-15

Ozone can react homogeneously with unsaturated organic compounds in buildings to generate undesirable products. However, these reactions can also occur on indoor surfaces, especially for low-volatility organics. Conversion rates of ozone with α-terpineol, a representative low-volatility compound, were quantified on surfaces that mimic indoor substrates. Rates were measured for α-terpineol adsorbed to beads of glass, polyvinylchloride (PVC), and dry latex paint, in a plug flow reactor. A newly defined second-order surface reaction rate coefficient, k(2), was derived from the flow reactor model. The value of k(2) ranged from 0.68 × 10(-14) cm(4)s(-1)molecule(-1) for α-terpineol adsorbed to PVC to 3.17 × 10(-14) cm(4)s(-1)molecule(-1) for glass, but was insensitive to relative humidity. Further, k(2) is only weakly influenced by the adsorbed mass but instead appears to be more strongly related to the interfacial activity α-terpineol. The minimum reaction probability ranged from 3.79 × 10(-6) for glass at 20% RH to 6.75 × 10(-5) for PVC at 50% RH. The combination of high equilibrium surface coverage and high reactivity for α-terpineol suggests that surface conversion rates are fast enough to compete with or even overwhelm other removal mechanisms in buildings such as gas-phase conversion and air exchange.

Conversion of rice husk into fermentable sugar by two stage hydrolysis

NASA Astrophysics Data System (ADS)

Salimi, M. N.; Lim, S. E.; Yusoff, A. H. M.; Jamlos, M. F.

2017-10-01

Rice husks, a complex lignocellulosic biomass which comprised of high cellulose content (38-50%), hemicellulose (23-32%) and lignin (15-25%) possesses the potential to pursue as low cost feedstock for production of ethanol. Dilute sulfuric acid at concentration of 1, 2, 3 (%, v/v) were used for pretreatments at varied hydrolysis time (15-60 min) and enzymatic saccharification at range of 45-60˚C and pH 4.5-6.0 were evaluated for conversion of rice husk’s cellulose and hemicellulose to fermentable sugars. The maximum yield of fermentable sugars from rice husks by dilute sulfuric acid (2%, 60 minutes) was 0.0751 g/l. Total fermentable sugar was identified using dinitrosalicylic acid (DNS) method and expressed in g/l. Enzymatic hydrolysis for conversion of cellulose to fermentable sugar has been studied by applying response surface methodology (RSM) and Analysis of Variance (ANOVA). Two independent variables namely initial pH and incubation temperature were considered using Central Composite Design (CCD). The determination coefficient, R2 obtained was 0.9848. This indicates that 98.48% capriciousness in the respond could be clarified by the ANOVA. Based on the data shown by Design Expert software, the optimum condition for total sugar production was at pH 6.0 and temperature 45˚C as it produced 0.5086 g/l of total sugar.

Defining the Ecological Coefficient of Performance for an Aircraft Propulsion System

NASA Astrophysics Data System (ADS)

Şöhret, Yasin

2018-05-01

The aircraft industry, along with other industries, is considered responsible these days regarding environmental issues. Therefore, the performance evaluation of aircraft propulsion systems should be conducted with respect to environmental and ecological considerations. The current paper aims to present the ecological coefficient of performance calculation methodology for aircraft propulsion systems. The ecological coefficient performance is a widely-preferred performance indicator of numerous energy conversion systems. On the basis of thermodynamic laws, the methodology used to determine the ecological coefficient of performance for an aircraft propulsion system is parametrically explained and illustrated in this paper for the first time. For a better understanding, to begin with, the exergy analysis of a turbojet engine is described in detail. Following this, the outputs of the analysis are employed to define the ecological coefficient of performance for a turbojet engine. At the end of the study, the ecological coefficient of performance is evaluated parametrically and discussed depending on selected engine design parameters and performance measures. The author asserts the ecological coefficient of performance to be a beneficial indicator for researchers interested in aircraft propulsion system design and related topics.

Franck-Condon Factors, R-Centroids Electronic Transition Moments, and Einstein Coefficients for Many Nitrogen and Oxygen Band Systems

DTIC Science & Technology

1992-02-01

5.21E-04 2.35E-04 1.071-04 4.93E-05 2.30E-05 1.088-05 5.06E-06 1.0615 1.0433 1.0266 1.0111 .9968 .9838 .9718 .9608 . 9505 .9406 .9304 3.03E-01 3.06E-01...3.49E-13 5.92E-16 1.23E-13 3.65E-13 .9056 1.9606 1.1888 7.9958 2.1710 . 0002 1.1879 1.0057 -1.4622 1.1520 1.0717 2.66E-01 3.32E-02 2.28E-01 9.36E-42 1.34E

Electron {sup 83}Rb/{sup 83m}Kr Source for the Energy Scale Monitoring in the KATRIN Experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zboril, Miroslav; Nuclear Physics Institute of the ASCR, p. r. i., CZ-25068 Rez; Collaboration: KATRIN Collaboration

The KATRIN (KArlsruhe TRItium Neutrino) experiment investigates the endpoint region of the tritium {beta}-spectrum aiming for the sensitivity on the neutrino mass of 0.2 eV (90% C.L.). A spectrometer of the MAC-E filter (Magnetic Adiabatic Collimation with an Electrostatic filter) type will be used for a total time of at least 5 years. An unrecognized shift of the filtering potential would directly influence the resulting neutrino mass. To continuously monitor the filtering potential the high voltage (HV) will be simultaneously applied to an additional MAC-E filter spectrometer. In this monitor spectrometer suitable electron sources based on atomic/nuclear standards will bemore » utilized. As one of such monitoring tools the solid {sup 83}Rb/{sup 83m}Kr source is intended. It provides conversion electrons from {sup 83m}Kr(t{sub 1/2} = 1.83 h) which is continuously generated by {sup 83}Rb(t{sub 1/2}{approx_equal}86 d). The Calibration and Monitoring task of the KATRIN project demands the long-term energy stability {Delta}E/E of the K-32 conversion electron line (E = 17.8 keV, {Gamma} = 2.7 eV) of {+-}1.6 ppm/month.« less

Posttranslational modifications of Sindbis virus glycoproteins: electrophoretic analysis of pulse-chase-labeled infected cells.

PubMed

Bonatti, S; Cancedda, F D

1982-04-01

Cytoplasmic extracts prepared from Sindbis virus-infected chicken embryo fibroblasts pulse-chase-labeled with [35S]methionine 6 h postinfection were analyzed on a highly resolving sodium dodecyl sulfate-gel either directly or after various treatments. The results we obtained suggest that (i) the proteolytic cleavage which converts PE2 to E2 glycoprotein takes place intracellularly, before or at least during the formation of complex-type oligosaccharide side chains; and (ii) E1 glycoprotein undergoes a complex maturation pattern. Newly synthesized E1 has a molecular weight of 53,000: shortly thereafter, this 53,000 (53K) form was converted to a 50K form. Subsequently, the 50K form decreased its apparent molecular weight progressively and eventually comigrated with E1 glycoprotein present in the extracellular virus, which displays a molecular weight of 51,000 to 52,000. The conversion of the 53K to the 50K form was not the result of a proteolytic processing and did not depend on glycosylation or disulfide bridge formation and exchange. The possible mechanisms of this conversion are discussed. The second conversion step (from the 50K to the 51-52K form) was due to the formation of complex-type oligosaccharide and was reversed by incubating the cellular extracts with neuraminidase before electrophoretic analysis.

Stormtime ring current and radiation belt ion transport: Simulations and interpretations

NASA Technical Reports Server (NTRS)

Lyons, Larry R.; Gorney, David J.; Chen, Margaret W.; Schulz, Michael

1995-01-01

We use a dynamical guiding-center model to investigate the stormtime transport of ring current and radiation-belt ions. We trace the motion of representative ions' guiding centers in response to model substorm-associated impulses in the convection electric field for a range of ion energies. Our simple magnetospheric model allows us to compare our numerical results quantitatively with analytical descriptions of particle transport, (e.g., with the quasilinear theory of radial diffusion). We find that 10-145-keV ions gain access to L approximately 3, where they can form the stormtime ring current, mainly from outside the (trapping) region in which particles execute closed drift paths. Conversely, the transport of higher-energy ions (approximately greater than 145 keV at L approximately 3) turns out to resemble radial diffusion. The quasilinear diffusion coefficient calculated for our model storm does not vary smoothly with particle energy, since our impulses occur at specific (although randomly determined) times. Despite the spectral irregularity, quasilinear theory provides a surprisingly accurate description of the transport process for approximately greater than 145-keV ions, even for the case of an individual storm. For 4 different realizations of our model storm, the geometric mean discrepancies between diffusion coefficients D(sup sim, sub LL) obtained from the simulations and the quasilinear diffusion coefficient D(sup ql, sub LL) amount to factors of 2.3, 2.3, 1.5, and 3.0, respectively. We have found that these discrepancies between D(sup sim, sub LL) and D(sup ql, sub LL) can be reduced slightly by invoking drift-resonance broadening to smooth out the sharp minima and maxima in D(sup ql, sub LL). The mean of the remaining discrepancies between D(sup sim, sub LL) and D(sup ql, sub LL) for the 4 different storms then amount to factors of 1.9, 2.1, 1.5, and 2.7, respectively. We find even better agreement when we reduce the impulse amplitudes systematically in a given model storm (e.g., reduction of all the impulse amplitudes by half reduces the discrepancy factor by at least its square root) and also when we average our results over an ensemble of 20 model storms (agreement is within a factor of 1.2 without impulse-amplitude reduction). We use our simulation results also to map phase-space densities f in accordance with Liouville's theorem. We find that the stormtime transport of approximately greater than 145-keV ions produces little change in f-bar the drift-averaged phase-space density on any drift shell of interest. However, the stormtime transport produces a major enhancement from the pre-storm phase-space density at energies approximately 30-145 keV, which are representative of the stormtime ring current.

Quantum size and magnesium composition effects on the optical absorption in the MgxZn(1-x)O/ZnO quantum well

NASA Astrophysics Data System (ADS)

Dakhlaoui, Hassen ben Bechir; Mouna, Nefzi

2018-02-01

In this work, we investigated the effects of polarizations and structural parameters on the optical absorption coefficient (OAC) and the intersubband transition between the three lowest energy levels E1,E2 , and E3 in the MgxZn(1-x)O/ZnO single quantum well. The energy of the electron in each level and its respective wavefunction are calculated by the numerical solution of Schrödinger and Poisson equations self-consistently using an effective mass approximation. Our findings exhibit that the intersubband transitions, ΔE12 and ΔE13 , can be altered and controlled by varying the quantum well width and the magnesium composition, x. Moreover, our results suggest that the optical absorption coefficients, α12 and α13 , can be modulated principally by adjusting the quantum well width, especially the optical absorption coefficient (α12), which presents a red shift by raising the quantum well thickness. Contrary to α12 , the optical absorption coefficient, α13 , can present either a red or a blue shift by increasing the quantum well width. The process responsible for this behavior, which can be suitable for optoelectronic device applications, is discussed here in detail.

Predicting Salt Permeability Coefficients in Highly Swollen, Highly Charged Ion Exchange Membranes.

PubMed

Kamcev, Jovan; Paul, Donald R; Manning, Gerald S; Freeman, Benny D

2017-02-01

This study presents a framework for predicting salt permeability coefficients in ion exchange membranes in contact with an aqueous salt solution. The model, based on the solution-diffusion mechanism, was tested using experimental salt permeability data for a series of commercial ion exchange membranes. Equilibrium salt partition coefficients were calculated using a thermodynamic framework (i.e., Donnan theory), incorporating Manning's counterion condensation theory to calculate ion activity coefficients in the membrane phase and the Pitzer model to calculate ion activity coefficients in the solution phase. The model predicted NaCl partition coefficients in a cation exchange membrane and two anion exchange membranes, as well as MgCl 2 partition coefficients in a cation exchange membrane, remarkably well at higher external salt concentrations (>0.1 M) and reasonably well at lower external salt concentrations (<0.1 M) with no adjustable parameters. Membrane ion diffusion coefficients were calculated using a combination of the Mackie and Meares model, which assumes ion diffusion in water-swollen polymers is affected by a tortuosity factor, and a model developed by Manning to account for electrostatic effects. Agreement between experimental and predicted salt diffusion coefficients was good with no adjustable parameters. Calculated salt partition and diffusion coefficients were combined within the framework of the solution-diffusion model to predict salt permeability coefficients. Agreement between model and experimental data was remarkably good. Additionally, a simplified version of the model was used to elucidate connections between membrane structure (e.g., fixed charge group concentration) and salt transport properties.

Preparation and Degradation of Polysilylenes

DTIC Science & Technology

1991-05-02

Grignard reagent formation from Mg and alkyl iodides in comparison with less reactive alkyl chlorides 2 3 . Electron transfer to the chlorides occur at...stoichiometric balance of reagents and nearly complete conversions (e.g. DPN-100 at 99% conversion in a homogeneous polycondensation with exact stoichiometric...the magnesium surface, whereas alkyl iodides accept electrons through Ŝ. larger distance and could not efficiently form organomagneslum reagents but

Measures of the environmental footprint of the front end of the nuclear fuel cycle

DOE Office of Scientific and Technical Information (OSTI.GOV)

E. Schneider; B. Carlsen; E. Tavrides

2013-11-01

Previous estimates of environmental impacts associated with the front end of the nuclear fuel cycle (FEFC) have focused primarily on energy consumption and CO2 emissions. Results have varied widely. This work builds upon reports from operating facilities and other primary data sources to build a database of front end environmental impacts. This work also addresses land transformation and water withdrawals associated with the processes of the FEFC. These processes include uranium extraction, conversion, enrichment, fuel fabrication, depleted uranium disposition, and transportation. To allow summing the impacts across processes, all impacts were normalized per tonne of natural uranium mined as wellmore » as per MWh(e) of electricity produced, a more conventional unit for measuring environmental impacts that facilitates comparison with other studies. This conversion was based on mass balances and process efficiencies associated with the current once-through LWR fuel cycle. Total energy input is calculated at 8.7 x 10- 3 GJ(e)/MWh(e) of electricity and 5.9 x 10- 3 GJ(t)/MWh(e) of thermal energy. It is dominated by the energy required for uranium extraction, conversion to fluoride compound for subsequent enrichment, and enrichment. An estimate of the carbon footprint is made from the direct energy consumption at 1.7 kg CO2/MWh(e). Water use is likewise dominated by requirements of uranium extraction, totaling 154 L/MWh(e). Land use is calculated at 8 x 10- 3 m2/MWh(e), over 90% of which is due to uranium extraction. Quantified impacts are limited to those resulting from activities performed within the FEFC process facilities (i.e. within the plant gates). Energy embodied in material inputs such as process chemicals and fuel cladding is identified but not explicitly quantified in this study. Inclusion of indirect energy associated with embodied energy as well as construction and decommissioning of facilities could increase the FEFC energy intensity estimate by a factor of up to 2.« less

Study electron transport coefficients for Ar, O2 and their mixtures by using EEDF program

NASA Astrophysics Data System (ADS)

Majeed, D. S. Abdul; Hussein, B. J.; Jassim, M. K.

2018-05-01

We calculated the electron transport coefficient in Ar, O2 and their mixtures for ratio of E/N where E denotes the electric field and N the density of gas atoms from 5 – 600 Td 1Td = 10-17 V.cm2. The result and parameters mean energy mobility drift velocity and others are calculated by solving Boltzmann equation. We study these gases because of its importance in thermal plasma such as shielding gas for arc welding of metals and alloys. These results are useful to find best gas mixtures to reach appropriate transport parameter and to derive the same relevant cross section data.

Increased expression of phosphorylated forms of RNA-dependent protein kinase and eukaryotic initiation factor 2α may signal skeletal muscle atrophy in weight-losing cancer patients

PubMed Central

Eley, H L; Skipworth, R J E; Deans, D A C; Fearon, K C H; Tisdale, M J

2007-01-01

Previous studies suggest that the activation (autophosphorylation) of dsRNA-dependent protein kinase (PKR) can stimulate protein degradation, and depress protein synthesis in skeletal muscle through phosphorylation of the translation initiation factor 2 (eIF2) on the α-subunit. To understand whether these mediators are important in muscle wasting in cancer patients, levels of the phospho forms of PKR and eIF2α have been determined in rectus abdominus muscle of weight losing patients with oesophago-gastric cancer, in comparison with healthy controls. Levels of both phospho PKR and phospho eIF2α were significantly enhanced in muscle of cancer patients with weight loss irrespective of the amount and there was a linear relationship between phosphorylation of PKR and phosphorylation of eIF2α (correlation coefficient 0.76, P=0.005). This suggests that phosphorylation of PKR led to phosphorylation of eIF2α. Myosin levels decreased as the weight loss increased, and there was a linear relationship between myosin expression and the extent of phosphorylation of eIF2α (correlation coefficient 0.77, P=0.004). These results suggest that phosphorylation of PKR may be an important initiator of muscle wasting in cancer patients. PMID:18087277

Performance of MIDAS Over East African Longitude Sector: Case Study During 4-14 March 2012 Quiet to Disturbed Geomagnetic Conditions

NASA Astrophysics Data System (ADS)

Giday, Nigussie M.; Katamzi-Joseph, Zama T.

2018-02-01

This study investigates the performance of a tomographic algorithm, Multi-Instrument and Data Analysis System (MIDAS), during an extended period of 4-14 March 2012, containing moderate and strong geomagnetic storms conditions, over an understudied and data scarce Eastern African longitude sector. Nonetheless, a relatively better distribution of Global Navigation Satellite Systems stations exists along a narrow longitude sector between 30°E and 44°E and latitude range of 30°S and 36°N that spans the equatorial, middle-, and low-latitude ionosphere. Then results are compared with independent global models such as International Reference Ionosphere 2012 (IRI-2012) and global ionosphere map (GIM). MIDAS performance was better than that of the IRI-2012 and GIM models in terms of capturing the diurnal trends as well as the short temporal total electron content (TEC) structures, with least root-mean-square errors (RMSEs). Overall, MIDAS results showed better agreement with the observation vertical TEC (VTEC) with computed maximum correlation coefficient (r) of 0.99 and minimum root-mean-square error (RMSE) of 2.91 TEC unit (1 TECU = 1,016 el m-2 over all the test stations and the validation days. Conversely, for the IRI-2012 and GIM TEC estimates, the corresponding maximum computed r values were 0.93 and 0.99, respectively, while the minimum RMSEs were 13.03 TECU and 6.52 TECU, respectively, for all the test stations and the validation days.

A polymer tandem solar cell with 10.6% power conversion efficiency.

PubMed

You, Jingbi; Dou, Letian; Yoshimura, Ken; Kato, Takehito; Ohya, Kenichiro; Moriarty, Tom; Emery, Keith; Chen, Chun-Chao; Gao, Jing; Li, Gang; Yang, Yang

2013-01-01

An effective way to improve polymer solar cell efficiency is to use a tandem structure, as a broader part of the spectrum of solar radiation is used and the thermalization loss of photon energy is minimized. In the past, the lack of high-performance low-bandgap polymers was the major limiting factor for achieving high-performance tandem solar cell. Here we report the development of a high-performance low bandgap polymer (bandgap <1.4 eV), poly[2,7-(5,5-bis-(3,7-dimethyloctyl)-5H-dithieno[3,2-b:2',3'-d]pyran)-alt-4,7-(5,6-difluoro-2,1,3-benzothia diazole)] with a bandgap of 1.38 eV, high mobility, deep highest occupied molecular orbital. As a result, a single-junction device shows high external quantum efficiency of >60% and spectral response that extends to 900 nm, with a power conversion efficiency of 7.9%. The polymer enables a solution processed tandem solar cell with certified 10.6% power conversion efficiency under standard reporting conditions (25 °C, 1,000 Wm(-2), IEC 60904-3 global), which is the first certified polymer solar cell efficiency over 10%.

A polymer tandem solar cell with 10.6% power conversion efficiency

PubMed Central

You, Jingbi; Dou, Letian; Yoshimura, Ken; Kato, Takehito; Ohya, Kenichiro; Moriarty, Tom; Emery, Keith; Chen, Chun-Chao; Gao, Jing; Li, Gang; Yang, Yang

2013-01-01

An effective way to improve polymer solar cell efficiency is to use a tandem structure, as a broader part of the spectrum of solar radiation is used and the thermalization loss of photon energy is minimized. In the past, the lack of high-performance low-bandgap polymers was the major limiting factor for achieving high-performance tandem solar cell. Here we report the development of a high-performance low bandgap polymer (bandgap <1.4 eV), poly[2,7-(5,5-bis-(3,7-dimethyloctyl)-5H-dithieno[3,2-b:2′,3′-d]pyran)-alt-4,7-(5,6-difluoro-2,1,3-benzothia diazole)] with a bandgap of 1.38 eV, high mobility, deep highest occupied molecular orbital. As a result, a single-junction device shows high external quantum efficiency of >60% and spectral response that extends to 900 nm, with a power conversion efficiency of 7.9%. The polymer enables a solution processed tandem solar cell with certified 10.6% power conversion efficiency under standard reporting conditions (25 °C, 1,000 Wm−2, IEC 60904-3 global), which is the first certified polymer solar cell efficiency over 10%. PMID:23385590

SPECTRAL CORRECTION FACTORS FOR CONVENTIONAL NEUTRON DOSE METERS USED IN HIGH-ENERGY NEUTRON ENVIRONMENTS-IMPROVED AND EXTENDED RESULTS BASED ON A COMPLETE SURVEY OF ALL NEUTRON SPECTRA IN IAEA-TRS-403.

PubMed

Oparaji, U; Tsai, Y H; Liu, Y C; Lee, K W; Patelli, E; Sheu, R J

2017-06-01

This paper presents improved and extended results of our previous study on corrections for conventional neutron dose meters used in environments with high-energy neutrons (En > 10 MeV). Conventional moderated-type neutron dose meters tend to underestimate the dose contribution of high-energy neutrons because of the opposite trends of dose conversion coefficients and detection efficiencies as the neutron energy increases. A practical correction scheme was proposed based on analysis of hundreds of neutron spectra in the IAEA-TRS-403 report. By comparing 252Cf-calibrated dose responses with reference values derived from fluence-to-dose conversion coefficients, this study provides recommendations for neutron field characterization and the corresponding dose correction factors. Further sensitivity studies confirm the appropriateness of the proposed scheme and indicate that (1) the spectral correction factors are nearly independent of the selection of three commonly used calibration sources: 252Cf, 241Am-Be and 239Pu-Be; (2) the derived correction factors for Bonner spheres of various sizes (6"-9") are similar in trend and (3) practical high-energy neutron indexes based on measurements can be established to facilitate the application of these correction factors in workplaces. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Diminiode thermionic conversion with 111-iridium electrodes

NASA Technical Reports Server (NTRS)

Koeger, E. W.; Bair, V. L.; Morris, J. F.

1976-01-01

Preliminary data indicating thermionic-conversion potentialities for a 111-iridium emitter and collector spaced 0.2 mm apart are presented. These results comprise output densities of current and of power as functions of voltage for three sets of emitter, collector, and reservoir temperatures: 1553, 944, 561 K; 1605, 898, 533 K; and 1656, 1028, 586 K. For the 1605 K evaluation, estimates produced work-function values of 2.22 eV for the emitter and 1.63 eV for the collector with a 2.0-eV barrier index (collector work function plus interelectrode voltage drop) corresponding to the maximum output of 5.5 W/sq cm at 0.24 volt. The current, voltage curve for the 1656 K 111-iridium diminiode yields a 6.2 W/sq cm maximum at 0.25 volt and is comparable with the 1700 K envelope for a diode with an etched-rhenium emitter and a 0.025-mm electrode gap made by TECO and evaluated by NASA.

Transport coefficients in high-temperature ionized air flows with electronic excitation

NASA Astrophysics Data System (ADS)

Istomin, V. A.; Oblapenko, G. P.

2018-01-01

Transport coefficients are studied in high-temperature ionized air mixtures using the modified Chapman-Enskog method. The 11-component mixture N2/N2+/N /N+/O2/O2+/O /O+/N O /N O+/e- , taking into account the rotational and vibrational degrees of freedom of molecules and electronic degrees of freedom of both atomic and molecular species, is considered. Using the PAINeT software package, developed by the authors of the paper, in wide temperature range calculations of the thermal conductivity, thermal diffusion, diffusion, and shear viscosity coefficients for an equilibrium ionized air mixture and non-equilibrium flow conditions for mixture compositions, characteristic of those in shock tube experiments and re-entry conditions, are performed. For the equilibrium air case, the computed transport coefficients are compared to those obtained using simplified kinetic theory algorithms. It is shown that neglecting electronic excitation leads to a significant underestimation of the thermal conductivity coefficient at temperatures higher than 25 000 K. For non-equilibrium test cases, it is shown that the thermal diffusion coefficients of neutral species and the self-diffusion coefficients of all species are strongly affected by the mixture composition, while the thermal conductivity coefficient is most strongly influenced by the degree of ionization of the flow. Neglecting electronic excitation causes noticeable underestimation of the thermal conductivity coefficient at temperatures higher than 20 000 K.

40 CFR 60.85 - Test methods and procedures.

Code of Federal Regulations, 2014 CFR

2014-07-01

... the following equation: E = (CQsd) / (PK) where: E = emission rate of acid mist or SO2 kg/metric ton... = volumetric flow rate of the effluent gas, dscm/hr (dscf/hr). P = production rate of 100 percent H2SO4, metric ton/hr (ton/hr). K = conversion factor, 1000 g/kg (1.0 lb/lb). (2) Method 8 shall be used to determine...

Diffusion of water-soluble sorptive drugs in HEMA/MAA hydrogels.

PubMed

Liu, D E; Dursch, T J; Taylor, N O; Chan, S Y; Bregante, D T; Radke, C J

2016-10-10

We measure and, for the first time, theoretically predict four prototypical aqueous-drug diffusion coefficients in five soft-contact-lens material hydrogels where solute-specific adsorption is pronounced. Two-photon fluorescence confocal microscopy and UV/Vis-absorption spectrophotometry assess transient solute concentration profiles and concentration histories, respectively. Diffusion coefficients are obtained for acetazolamide, riboflavin, sodium fluorescein, and theophylline in 2-hydroxyethyl methacrylate/methacrylic acid (HEMA/MAA) copolymer hydrogels as functions of composition, equilibrium water content (30-90%), and aqueous pH (2 and 7.4). At pH2, MAA chains are nonionic, whereas at pH7.4, MAA chains are anionic (pKa≈5.2). All studied prototypical drugs specifically interact with HEMA and nonionic MAA (at pH2) moieties. Conversely, none of the prototypical drugs adsorb specifically to anionic MAA (at pH7.4) chains. As expected, diffusivities of adsorbing solutes are significantly diminished by specific interactions with hydrogel strands. Despite similar solute size, relative diffusion coefficients in the hydrogels span several orders of magnitude because of varying degrees of solute interactions with hydrogel-polymer chains. To provide a theoretical framework for the new diffusion data, we apply an effective-medium model extended for solute-specific interactions with hydrogel copolymer strands. Sorptive-diffusion kinetics is successfully described by local equilibrium and Henry's law. All necessary parameters are determined independently. Predicted diffusivities are in good agreement with experiment. Copyright © 2016 Elsevier B.V. All rights reserved.

Junctional E-cadherin/p120-catenin Is Correlated with the Absence of Supporting Cells to Hair Cells Conversion in Postnatal Mice Cochleae.

PubMed

Luo, Wen-Wei; Wang, Xin-Wei; Ma, Rui; Chi, Fang-Lu; Chen, Ping; Cong, Ning; Gu, Yu-Yan; Ren, Dong-Dong; Yang, Juan-Mei

2018-01-01

Notch inhibition is known to generate supernumerary hair cells (HCs) at the expense of supporting cells (SCs) in the mammalian inner ear. However, inhibition of Notch activity becomes progressively less effective at inducing SC-to-HC conversion in the postnatal cochlea and balance organs as the animal ages. It has been suggested that the SC-to-HC conversion capacity is inversely correlated with E-cadherin accumulation in postnatal mammalian utricles. However, whether E-cadherin localization is linked to the SC-to-HC conversion capacity in the mammalian inner ear is poorly understood. In the present study, we treated cochleae from postnatal day 0 (P0) with the Notch signaling inhibitor DAPT and observed apparent SC-to-HC conversion along with E-cadherin/p120ctn disruption in the sensory region. In addition, the SC-to-HC conversion capacity and E-cadherin/p120ctn disorganization were robust in the apex but decreased toward the base. We further demonstrated that the ability to regenerate HCs and the disruption of E-cadherin/p120ctn concomitantly decreased with age and ceased at P7, even after extended DAPT treatments. This timing is consistent with E-cadherin/p120ctn accumulation in the postnatal cochleae. These results suggest that the decreasing capacity of SCs to transdifferentiate into HCs correlates with E-cadherin/p120ctn localization in the postnatal cochleae, which might account for the absence of SC-to-HC conversion in the mammalian cochlea.

Rational Design of Zinc Phosphide Heterojunction Photovoltaics

NASA Astrophysics Data System (ADS)

Bosco, Jeffrey Paul

The prospect of terawatt-scale electricity generation using a photovoltaic (PV) device places strict requirements on the active semiconductor optoelectronic properties and elemental abundance. After reviewing the constraints placed on an ``earth-abundant'' solar absorber, we find zinc phosphide (α-Zn 3P2) to be an ideal candidate. In addition to its near-optimal direct band gap of 1.5 eV, high visible-light absorption coefficient (>10. 4cm-1), and long minority-carrier diffusion length (>5 μm), Zn3P 2 is composed of abundant Zn and P elements and has excellent physical properties for scalable thin-film deposition. However, to date, a Zn 3P2 device of sufficient efficiency for commercial applications has not been demonstrated. Record efficiencies of 6.0% for multicrystalline and 4.3% for thin-film cells have been reported, respectively. Performance has been limited by the intrinsic p-type conductivity of Zn3P 2 which restricts us to Schottky and heterojunction device designs. Due to our poor understanding of Zn3P2 interfaces, an ideal heterojunction partner has not yet been found. The goal of this thesis is to explore the upper limit of solar conversion efficiency achievable with a Zn3P2 absorber through the design of an optimal heterojunction PV device. To do so, we investigate three key aspects of material growth, interface energetics, and device design. First, the growth of Zn3P2 on GaAs(001) is studied using compound-source molecular-beam epitaxy (MBE). We successfully demonstrate the pseudomorphic growth of Zn3P2 epilayers of controlled orientation and optoelectronic properties. Next, the energy-band alignments of epitaxial Zn3P2 and II-VI and III-V semiconductor interfaces are measured via high-resolution x-ray photoelectron spectroscopy in order to determine the most appropriate heterojunction partner. From this work, we identify ZnSe as a nearly ideal n-type emitter for a Zn3P 2 PV device. Finally, various II-VI/Zn3P2 heterojunction solar cells designs are fabricated, including substrate and superstrate architectures, and evaluated based on their solar conversion efficiency.

Correction factors for on-line microprobe analysis of multielement alloy systems

NASA Technical Reports Server (NTRS)

Unnam, J.; Tenney, D. R.; Brewer, W. D.

1977-01-01

An on-line correction technique was developed for the conversion of electron probe X-ray intensities into concentrations of emitting elements. This technique consisted of off-line calculation and representation of binary interaction data which were read into an on-line minicomputer to calculate variable correction coefficients. These coefficients were used to correct the X-ray data without significantly increasing computer core requirements. The binary interaction data were obtained by running Colby's MAGIC 4 program in the reverse mode. The data for each binary interaction were represented by polynomial coefficients obtained by least-squares fitting a third-order polynomial. Polynomial coefficients were generated for most of the common binary interactions at different accelerating potentials and are included. Results are presented for the analyses of several alloy standards to demonstrate the applicability of this correction procedure.

Improved conversion efficiency of dye sensitized solar cell using Zn doped TiO{sub 2}-ZrO{sub 2} nanocomposite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tomar, Laxmi J., E-mail: laxmi-tomar86@yahoo.com; Bhatt, Piyush J.; Desai, Rahul K.

TiO{sub 2}-ZrO{sub 2} and Zn doped TiO{sub 2}-ZrO{sub 2} nanocomposites were prepared by hydrothermal method for dye sensitized solar cell (DSSC) application. The structural and optical properties were investigated by X –ray diffraction (XRD) and UV-Visible spectroscopy respectively. XRD results revealed the formation of material in nano size. The average crystallite size is 22.32 nm, 17.41 nm and 6.31 nm for TiO{sub 2}, TiO{sub 2}-ZrO{sub 2} and Zn doped TiO{sub 2}-ZrO{sub 2} nanocomposites respectively. The optical bandgap varies from 2.04 eV to 3.75 eV. Dye sensitized solar cells were fabricated using the prepared material. Pomegranate juice was used as a sensitizer and graphitemore » coated conducting glass plate was used as counter electrode. The I – V characteristics were recorded to measure photo response of DSSC. Photovoltaic parameter like open circuit voltage, power conversion efficiency, and fill factor were evaluated for fabricated solar cell. The power conversion efficiency of DSSC fabricated with TiO{sub 2}, TiO{sub 2}-ZrO{sub 2} and Zn doped TiO{sub 2}-ZrO{sub 2} nanocomposites were found 0.71%, 1.97% and 4.58% respectively.« less

Risk Characterization for Future Training Scenarios at the Massachusetts Military Reservation (MMR), Final Results

DTIC Science & Technology

2005-08-01

1979) 0.63d ocK f= owK (1) where Kow = octanol to water partitioning coefficient, L/kg foc = fraction of organic carbon of the soil Barber...Software 59 2-Methylthiophene 554-14-3 0.135 EPI Software 60 2-Nitrophenol 88-75-5 0.039 EPI Software 61 2- Octanone 111-13-7 0.148 EPI Software 62 2...Nitrophenol 88-75-5 6.09E-09 1.72E-12 2- Octanone 111-13-7 2.56E-11 7.23E-15 2-Pentanone 107-87-9 1.83E-08 5.18E-12 2-Propanol 67-63-0 4.08E-09 1.15E-12 2

Hopkins during SODI-DCMIX 2 Experiment

NASA Image and Video Library

2013-11-30

ISS038-E-009255 (26 Nov. 2013) --- In the International Space Station?s Destiny laboratory, NASA astronaut Michael Hopkins, Expedition 38 flight engineer, prepares to install and activate the Selectable Optics Diagnostic Instrument (SODI) cell array two in the Microgravity Science Glovebox (MSG) for the Selectable Optics Diagnostic Instrument-Diffusion Coefficient in Mixtures 2 (SODI-DCMIX 2) experiment. SODI-DCMIX 2 is supporting research to determine diffusion coefficients in different petroleum field samples and refine petroleum reservoir models to help lead to more efficient extraction of oil resources.

Hopkins during SODI-DCMIX 2 Experiment

NASA Image and Video Library

2013-11-30

ISS038-E-009253 (26 Nov. 2013) --- In the International Space Station’s Destiny laboratory, NASA astronaut Michael Hopkins, Expedition 38 flight engineer, prepares to install and activate the Selectable Optics Diagnostic Instrument (SODI) cell array two in the Microgravity Science Glovebox (MSG) for the Selectable Optics Diagnostic Instrument-Diffusion Coefficient in Mixtures 2 (SODI-DCMIX 2) experiment. SODI-DCMIX 2 is supporting research to determine diffusion coefficients in different petroleum field samples and refine petroleum reservoir models to help lead to more efficient extraction of oil resources.

Casting of Halide and Fluoride Alloys for Laser Windows

DTIC Science & Technology

1976-02-15

exhibit at least microplastic behavior at room temper- ature, it might be expected that their fracture strength will follow a Petch relationship...polishing and testing. Only later was it discovered that this particular annealing procedure degraded the optical properties (i. e., 5. 25 pm Pb- sorption ... sorption coefficient of 4. 8 x 10’ c~ii 1 TABLE 3-5 AP PARENT ABSOi. -)N COEFFICIENTS AN~D SCATTERING CF2CASTING HN 1 5.25 pm Absorption Coefficient

Optical band gap and spectroscopic study of lithium alumino silicate glass containing Y3+ ions.

PubMed

Shakeri, M S; Rezvani, M

2011-09-01

The effect of different amounts of Y2O3 dopant on lithium alumino silicate (LAS) glass has been studied in this work. Glasses having 14.8Li2O-20Al2O3-65.2SiO2 (wt%) composition accompanied with Y2O3 dopant were prepared by normal melting process. In order to calculate the absorption coefficient of samples, transmittance and reflectance spectra of polished samples were measured in the room temperature. Optical properties i.e. Fermi energy level, direct and indirect optical band gaps and Urbach energy were calculated using functionality of extinction coefficient from Fermi-Dirac distribution function, Tauc's plot and the exponential part of absorption coefficient diagram, respectively. It has been clarified that variation in mentioned optical parameters is associated with the changes in physical properties of samples i.e. density or molar mass. On the other hand, increasing of Y3+ ions in the glassy microstructure of samples provides a semiconducting character to LAS glass by reducing the direct and indirect optical band gaps of glass samples from 1.97 to 1.67 and 3.46 to 2.1 (eV), respectively. These changes could be attributed to the role of Y3+ ions as the network former in the track of SiO4 tetrahedrals. Copyright © 2011 Elsevier B.V. All rights reserved.

Reciprocity principle in duct acoustics

NASA Technical Reports Server (NTRS)

Cho, Y.-C.

1979-01-01

Various reciprocity relations in duct acoustics have been derived on the basis of the spatial reciprocity principle implied in Green's functions for linear waves. The derivation includes the reciprocity relations between mode conversion coefficients for reflection and transmission in nonuniform ducts, and the relation between the radiation of a mode from an arbitrarily terminated duct and the absorption of an externally incident plane wave by the duct. Such relations are well defined as long as the systems remain linear, regardless of acoustic properties of duct nonuniformities which cause the mode conversions.

Measurement of the Onsager coefficients of mixed ionic-electronic conduction in oxides

NASA Astrophysics Data System (ADS)

Lee, Doh-Kwon; Yoo, Han-Ill

2007-06-01

In the phenomenon of mixed ionic-electronic conduction in solid state, a flow of mobile ions (Ji) may be induced not only directly by their own electrochemical potential gradient (∇ηi) , but also indirectly by that of electrons (∇ηe) , and vice versa for a flow of electrons (Je) or Jm=-Lmn∇ηn (m,n=i,e) . We have recently succeeded in determining experimentally all the four Onsager coefficients Lmn on the system of TiO2 , and reported [Phys. Rev. Lett. 97, 255901 (2006)] that the Onsager reciprocity is verified within 1.3% error bound (Lie/Lei=0.993±0.013) and contrary to the general belief, the cross coefficient is not only not negligible but also even larger than a direct one (1.5⩽Lie/Lii⩽3.7) . This paper details the experimental technique which allows one to measure all the Onsager coefficients in a mixed conductor oxide.

Natural dye sensitizer from cassava (Manihot utilissima) leaves extract and its adsorption onto TiO2 photo-anode

NASA Astrophysics Data System (ADS)

Nurlela; Wibowo, R.; Gunlazuardi, J.

2017-04-01

Interaction between TiO2 and dyes sensitizer have been studied. The chlorophyll presents in the crude leave extract (CLE-dye) from cassava (Manihot utilissima) was immobilized on to the photo-anode, consists of TiO2 supported by fluor doped Tin oxide (SnO2-F) Glass. The TiO2 was prepared by Rapid Breakdown Anodization (RBA) method then immobilized on to glass coated by SnO2-F using doctor blade technique, to give CLE-dye/TiO2/SnO2-F/Glass photo-anode. The prepared photo-anode was characterized by UV-Vis-DRS, FTIR, XRD, SEM, electrochemical and spectro-electrochemical systems. In this study, the HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) energy level of the CLE-dye were empirically determined by cyclic voltammetry method, while spectro-electro-chemistry method was used to determine the coefficient of degradation and formation of the dyes, and diffusion coefficient of the hole recombination as well. Good anchoring between TiO2 with dye extracts (CLE-dye) can be seen from value of dye LUMO energy level (-4.26 eV), which is approaching the conduction band of TiO2 (-4.3 eV). The coefficient of degradation and formation of the CLE-dye showed a quasi reversible and diffusion coefficient hole recombination values were small, indicated that it is quite suitable as a sensitizer in a dyes sensitized solar cell.

Condensation and dissociation rates for gas phase metal clusters from molecular dynamics trajectory calculations

DOE PAGES

Yang, Huan; Goudeli, Eirini; Hogan, Christopher J.

2018-04-24

In gas phase synthesis systems, clusters form and grow via condensation, in which a monomer binds to an existing cluster. While a hard sphere equation is frequently used to predict the condensation rate coefficient, this equation neglects the influences of potential interactions and cluster internal energy on the condensation process. Here, we present a collision rate theory-Molecular Dynamics simulation approach to calculate condensation probabilities and condensation rate coefficients; we use this approach to examine atomic condensation onto 6-56 atom Au and Mg clusters. The probability of condensation depends upon the initial relative velocity ( v) between atom and cluster andmore » the initial impact parameter ( b). In all cases there is a well-defined region of b-v space where condensation is highly probable, and outside of which the condensation probability drops to zero. For Au clusters with more than 10 atoms, we find that at gas temperatures in the 300-1200 K range, the condensation rate coefficient exceeds the hard sphere rate coefficient by a factor of 1.5-2.0. Conversely, for Au clusters with 10 or fewer atoms, and for 14 atom and 28 atom Mg clusters, as cluster equilibration temperature increases the condensation rate coefficient drops to values below the hard sphere rate coefficient. Calculations also yield the self-dissociation rate coefficient, which is found to vary considerably with gas temperature. Finally, calculations results reveal that grazing (high b) atom-cluster collisions at elevated velocity (> 1000 m s -1) can result in the colliding atom rebounding (bounce) from the cluster surface or binding while another atom dissociates (replacement). In conclusion, the presented method can be applied in developing rate equations to predict material formation and growth rates in vapor phase systems.« less

Condensation and dissociation rates for gas phase metal clusters from molecular dynamics trajectory calculations.

PubMed

Yang, Huan; Goudeli, Eirini; Hogan, Christopher J

2018-04-28

In gas phase synthesis systems, clusters form and grow via condensation, in which a monomer binds to an existing cluster. While a hard-sphere equation is frequently used to predict the condensation rate coefficient, this equation neglects the influences of potential interactions and cluster internal energy on the condensation process. Here, we present a collision rate theory-molecular dynamics simulation approach to calculate condensation probabilities and condensation rate coefficients. We use this approach to examine atomic condensation onto 6-56-atom Au and Mg clusters. The probability of condensation depends upon the initial relative velocity (v) between atom and cluster and the initial impact parameter (b). In all cases, there is a well-defined region of b-v space where condensation is highly probable, and outside of which the condensation probability drops to zero. For Au clusters with more than 10 atoms, we find that at gas temperatures in the 300-1200 K range, the condensation rate coefficient exceeds the hard-sphere rate coefficient by a factor of 1.5-2.0. Conversely, for Au clusters with 10 or fewer atoms and for 14- and 28-atom Mg clusters, as cluster equilibration temperature increases, the condensation rate coefficient drops to values below the hard-sphere rate coefficient. Calculations also yield the self-dissociation rate coefficient, which is found to vary considerably with gas temperature. Finally, calculations results reveal that grazing (high b) atom-cluster collisions at elevated velocity (>1000 m s -1 ) can result in the colliding atom rebounding (bounce) from the cluster surface or binding while another atom dissociates (replacement). The presented method can be applied in developing rate equations to predict material formation and growth rates in vapor phase systems.

Condensation and dissociation rates for gas phase metal clusters from molecular dynamics trajectory calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Huan; Goudeli, Eirini; Hogan, Christopher J.

In gas phase synthesis systems, clusters form and grow via condensation, in which a monomer binds to an existing cluster. While a hard sphere equation is frequently used to predict the condensation rate coefficient, this equation neglects the influences of potential interactions and cluster internal energy on the condensation process. Here, we present a collision rate theory-Molecular Dynamics simulation approach to calculate condensation probabilities and condensation rate coefficients; we use this approach to examine atomic condensation onto 6-56 atom Au and Mg clusters. The probability of condensation depends upon the initial relative velocity ( v) between atom and cluster andmore » the initial impact parameter ( b). In all cases there is a well-defined region of b-v space where condensation is highly probable, and outside of which the condensation probability drops to zero. For Au clusters with more than 10 atoms, we find that at gas temperatures in the 300-1200 K range, the condensation rate coefficient exceeds the hard sphere rate coefficient by a factor of 1.5-2.0. Conversely, for Au clusters with 10 or fewer atoms, and for 14 atom and 28 atom Mg clusters, as cluster equilibration temperature increases the condensation rate coefficient drops to values below the hard sphere rate coefficient. Calculations also yield the self-dissociation rate coefficient, which is found to vary considerably with gas temperature. Finally, calculations results reveal that grazing (high b) atom-cluster collisions at elevated velocity (> 1000 m s -1) can result in the colliding atom rebounding (bounce) from the cluster surface or binding while another atom dissociates (replacement). In conclusion, the presented method can be applied in developing rate equations to predict material formation and growth rates in vapor phase systems.« less

Condensation and dissociation rates for gas phase metal clusters from molecular dynamics trajectory calculations

NASA Astrophysics Data System (ADS)

Yang, Huan; Goudeli, Eirini; Hogan, Christopher J.

2018-04-01

In gas phase synthesis systems, clusters form and grow via condensation, in which a monomer binds to an existing cluster. While a hard-sphere equation is frequently used to predict the condensation rate coefficient, this equation neglects the influences of potential interactions and cluster internal energy on the condensation process. Here, we present a collision rate theory-molecular dynamics simulation approach to calculate condensation probabilities and condensation rate coefficients. We use this approach to examine atomic condensation onto 6-56-atom Au and Mg clusters. The probability of condensation depends upon the initial relative velocity (v) between atom and cluster and the initial impact parameter (b). In all cases, there is a well-defined region of b-v space where condensation is highly probable, and outside of which the condensation probability drops to zero. For Au clusters with more than 10 atoms, we find that at gas temperatures in the 300-1200 K range, the condensation rate coefficient exceeds the hard-sphere rate coefficient by a factor of 1.5-2.0. Conversely, for Au clusters with 10 or fewer atoms and for 14- and 28-atom Mg clusters, as cluster equilibration temperature increases, the condensation rate coefficient drops to values below the hard-sphere rate coefficient. Calculations also yield the self-dissociation rate coefficient, which is found to vary considerably with gas temperature. Finally, calculations results reveal that grazing (high b) atom-cluster collisions at elevated velocity (>1000 m s-1) can result in the colliding atom rebounding (bounce) from the cluster surface or binding while another atom dissociates (replacement). The presented method can be applied in developing rate equations to predict material formation and growth rates in vapor phase systems.

Subtracting infrared renormalons from Wilson coefficients: Uniqueness and power dependences on ΛQCD

NASA Astrophysics Data System (ADS)

Mishima, Go; Sumino, Yukinari; Takaura, Hiromasa

2017-06-01

In the context of operator product expansion (OPE) and using the large-β0 approximation, we propose a method to define Wilson coefficients free from uncertainties due to IR renormalons. We first introduce a general observable X (Q2) with an explicit IR cutoff, and then we extract a genuine UV contribution XUV as a cutoff-independent part. XUV includes power corrections ˜(ΛQCD2/Q2)n which are independent of renormalons. Using the integration-by-regions method, we observe that XUV coincides with the leading Wilson coefficient in OPE and also clarify that the power corrections originate from UV region. We examine scheme dependence of XUV and single out a specific scheme favorable in terms of analytical properties. Our method would be optimal with respect to systematicity, analyticity and stability. We test our formulation with the examples of the Adler function, QCD force between Q Q ¯, and R -ratio in e+e- collision.

Fully Controllable Pancharatnam-Berry Metasurface Array with High Conversion Efficiency and Broad Bandwidth

PubMed Central

Liu, Chuanbao; Bai, Yang; Zhao, Qian; Yang, Yihao; Chen, Hongsheng; Zhou, Ji; Qiao, Lijie

2016-01-01

Metasurfaces have powerful abilities to manipulate the properties of electromagnetic waves flexibly, especially the modulation of polarization state for both linearly polarized (LP) and circularly polarized (CP) waves. However, the transmission efficiency of cross-polarization conversion by a single-layer metasurface has a low theoretical upper limit of 25% and the bandwidth is usually narrow, which cannot be resolved by their simple additions. Here, we efficiently manipulate polarization coupling in multilayer metasurface to promote the transmission of cross-polarization by Fabry-Perot resonance, so that a high conversion coefficient of 80–90% of CP wave is achieved within a broad bandwidth in the metasurface with C-shaped scatters by theoretical calculation, numerical simulation and experiments. Further, fully controlling Pancharatnam-Berry phase enables to realize polarized beam splitter, which is demonstrated to produce abnormal transmission with high conversion efficiency and broad bandwidth. PMID:27703254

Fluence-to-dose conversion coefficients based on the posture modification of Adult Male (AM) and Adult Female (AF) reference phantoms of ICRP 110

NASA Astrophysics Data System (ADS)

Galeano, D. C.; Santos, W. S.; Alves, M. C.; Souza, D. N.; Carvalho, A. B.

2016-04-01

The aim of this work was to modify the standing posture of the anthropomorphic reference phantoms of ICRP publication 110, AM (Adult Male) and AF (Adult Female), to the sitting posture. The change of posture was performed using the Visual Monte Carlo software (VMC) to rotate the thigh region of the phantoms and position it between the region of the leg and trunk. Scion Image software was used to reconstruct and smooth the knee and hip contours of the phantoms in a sitting posture. For 3D visualization of phantoms, the VolView software was used. In the change of postures, the organ and tissue masses were preserved. The MCNPX was used to calculate the equivalent and effective dose conversion coefficients (CCs) per fluence for photons for six irradiation geometries suggested by ICRP publication 110 (AP, PA, RLAT, LLAT, ROT and ISO) and energy range 0.010-10 MeV. The results were compared between the standing and sitting postures, for both sexes, in order to evaluate the differences of scattering and absorption of radiation for different postures. Significant differences in the CCs for equivalent dose were observed in the gonads, colon, prostate, urinary bladder and uterus, which are present in the pelvic region, and in organs distributed throughout the body, such as the lymphatic nodes, muscle, skeleton and skin, for the phantoms of both sexes. CCs for effective dose showed significant differences of up to 16% in the AP irradiation geometry, 27% in the PA irradiation geometry and 13% in the ROT irradiation geometry. These results demonstrate the importance of using phantoms in different postures in order to obtain more precise conversion coefficients for a given exposure scenario.

Use of three-dimensional speckle tracking to assess left ventricular myocardial mechanics: inter-vendor consistency and reproducibility of strain measurements.

PubMed

Badano, Luigi P; Cucchini, Umberto; Muraru, Denisa; Al Nono, Osama; Sarais, Cristiano; Iliceto, Sabino

2013-03-01

Since there is insufficient data available about the inter-vendor consistency of three-dimensional (3D) speckle-tracking (STE) measurements, we undertook this study to (i) assess the inter-vendor consistency of 3D LV global strain values obtained using two different scanners; (ii) identify the sources of inter-vendor inconsistencies, if any; and (iii) compare their respective intrinsic variability. Sixty patients (38 ± 12 years, 64% males) with a wide range of LV end-diastolic volumes (from 74 to 205 ml) and ejection fractions (from 17 to 70%) underwent two 3D LV data set acquisitions using VividE9 and Artida ultrasound systems. Global longitudinal (Lε), radial (Rε), circumferential (Cε) and area (Aε) strain values were obtained offline using the corresponding 3D STE softwares. Despite being significantly different, Lε showed the closest values between the two platforms (bias = 1.5%, limits of agreement (LOA) from -2.9 to -5.9%, P < 0.05). Artida produced significantly higher values of both Cε and Aε than VividE9 (bias = 6.6, LOA: -14.1 to 0.9%, and bias = 6.0, LOA = -28.2-8.6%, respectively, P < 0.001). Conversely, Rε values obtained with Artida were significantly lower than those measured using VividE9 platform (bias = -24.2, LOA: 1.5-49.9, P < 0.001). All strain components showed good reproducibility (intra-class correlation coefficients: 0.82-0.98), except for Rε by Artida, which showed only a moderate reproducibility. Apart from Lε, the inter-vendor agreement of Rε, Cε and Aε measured with Artida and VividE9 was poor. Reference values should be specific for each system and baseline and follow-up data in longitudinal studies should be obtained using the same 3D STE platform.

Estimation and comparison of effective dose (E) in standard chest CT by organ dose measurements and dose-length-product methods and assessment of the influence of CT tube potential (energy dependency) on effective dose in a dual-source CT.

PubMed

Paul, Jijo; Banckwitz, Rosemarie; Krauss, Bernhard; Vogl, Thomas J; Maentele, Werner; Bauer, Ralf W

2012-04-01

To determine effective dose (E) during standard chest CT using an organ dose-based and a dose-length-product-based (DLP) approach for four different scan protocols including high-pitch and dual-energy in a dual-source CT scanner of the second generation. Organ doses were measured with thermo luminescence dosimeters (TLD) in an anthropomorphic male adult phantom. Further, DLP-based dose estimates were performed by using the standard 0.014mSv/mGycm conversion coefficient k. Examinations were performed on a dual-source CT system (Somatom Definition Flash, Siemens). Four scan protocols were investigated: (1) single-source 120kV, (2) single-source 100kV, (3) high-pitch 120kV, and (4) dual-energy with 100/Sn140kV with equivalent CTDIvol and no automated tube current modulation. E was then determined following recommendations of ICRP publication 103 and 60 and specific k values were derived. DLP-based estimates differed by 4.5-16.56% and 5.2-15.8% relatively to ICRP 60 and 103, respectively. The derived k factors calculated from TLD measurements were 0.0148, 0.015, 0.0166, and 0.0148 for protocol 1, 2, 3 and 4, respectively. Effective dose estimations by ICRP 103 and 60 for single-energy and dual-energy protocols show a difference of less than 0.04mSv. Estimates of E based on DLP work equally well for single-energy, high-pitch and dual-energy CT examinations. The tube potential definitely affects effective dose in a substantial way. Effective dose estimations by ICRP 103 and 60 for both single-energy and dual-energy examinations differ not more than 0.04mSv. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Estimation of chromophoric dissolved organic matter in the Mississippi and Atchafalaya river plume regions using above-surface hyperspectral remote sensing

NASA Astrophysics Data System (ADS)

Zhu, Weining; Yu, Qian; Tian, Yong Q.; Chen, Robert F.; Gardner, G. Bernard

2011-02-01

A method for the inversion of hyperspectral remote sensing was developed to determine the absorption coefficient for chromophoric dissolved organic matter (CDOM) in the Mississippi and Atchafalaya river plume regions and the northern Gulf of Mexico, where water types vary from Case 1 to turbid Case 2. Above-surface hyperspectral remote sensing data were measured by a ship-mounted spectroradiometer and then used to estimate CDOM. Simultaneously, water absorption and attenuation coefficients, CDOM and chlorophyll fluorescence, turbidities, and other related water properties were also measured at very high resolution (0.5-2 m) using in situ, underwater, and flow-through (shipboard, pumped) optical sensors. We separate ag, the absorption coefficient a of CDOM, from adg (a of CDOM and nonalgal particles) based on two absorption-backscattering relationships. The first is between ad (a of nonalgal particles) and bbp (total particulate backscattering coefficient), and the second is between ap (a of total particles) and bbp. These two relationships are referred as ad-based and ap-based methods, respectively. Consequently, based on Lee's quasi-analytical algorithm (QAA), we developed the so-called Extended Quasi-Analytical Algorithm (QAA-E) to decompose adg, using both ad-based and ap-based methods. The absorption-backscattering relationships and the QAA-E were tested using synthetic and in situ data from the International Ocean-Colour Coordinating Group (IOCCG) as well as our own field data. The results indicate the ad-based method is relatively better than the ap-based method. The accuracy of CDOM estimation is significantly improved by separating ag from adg (R2 = 0.81 and 0.65 for synthetic and in situ data, respectively). The sensitivities of the newly introduced coefficients were also analyzed to ensure QAA-E is robust.

Effect of antioxidants on the dentin interface bond stability of adhesives exposed to hydrolytic degradation.

PubMed

Gotti, Valéria B; Feitosa, Victor P; Sauro, Salvatore; Correr-Sobrinho, Lourenço; Leal, Fernanda B; Stansbury, Jeffrey W; Correr, Américo B

2015-02-01

This study assessed the effect of antioxidants vitamin C (Vit. C), vitamin E (Vit. E) and quercetin (Querc) on the dentin bonding performance, degree of conversion, and rate of polymerization of three commercial adhesive systems (Adper Single Bond 2 [SB], Clearfil SE Bond [CSE], Adper Easy Bond [EB]). Human premolars were restored using antioxidant-doped adhesives. The samples were stored for 24 h in distilled water or 6 months under simulated pulpal pressure. Teeth were cut into sticks and the microtensile bond strength (μTBS) to dentin was tested in a universal testing machine. Qualitative nanoleakage analysis was performed from a central stick of each restored tooth. Degree of conversion and rate of polymerization of adhesive systems were evaluated in triplicate using real-time FT-IR. Although the inclusion of the antioxidants negatively affected the μTBS over 24 h, the antioxidant-doped adhesives maintained (SB-Vit. C, SB-Vit. E, CSE-Vit. C, EB-Querc) or increased (SB-Querc, CSE-Vit. E, CSE-Querc, EB-Vit. E, and EB-Vit. C) their μTBS during 6 months of storage. Only the μTBS of Adper Single Bond 2 dropped significantly after 6 months among the control groups. Slight changes in the nanoleakage pattern after aging were observed in all groups, except for the EB-control group, which showed a noteworthy increase in nanoleakage after 6 months, and for EB-Vit. C, which presented a remarkable decrease. A lower degree of conversion was obtained with all antioxidants in SB and EB, except for the EB-Vit. E group. Similar degrees of conversion were attained in control and experimental groups for CSE. The rate of polymerization was reduced in antioxidant-doped adhesives. The performance of antioxidants changed according to the adhesive system to which they were added, and antioxidant-doped adhesives appear to have a positive effect on the adhesive interface durability, since their bond strength obtained after 24 h was maintained or increased over time.

Robust Path Tracking of Autonomous Underwater Vehicles Using Sliding Modes

DTIC Science & Technology

1990-12-01

MDB REAL MQN , MWN ,MDSN REAL QHADOTQHAT,THADOT,THAT C C YAW HYDRODYNAMIC COEFFICIENTS C REAL NPDOT,NRDOTNPQ , NQR REAL NVDOT , NP ,NR ,NVQ REAL NWP...NRDOT--3.4E-3-,NPQ .s-2.1E-2 , NQR .s2.7E-3, & NVDOT-1.2E-3 , NP --8.4E-4 ,NR --1.6E-2 ,NVQ - -1.E-2, -& NWP --1.75-2 , NWR -7.4E-3 ,NV -.-7.4E-3 ,NVW... NQR *Q*R)- +(RHO/2)*L**4*(NP*U*P+ & NR*U*R + NVQ*V*Q-+NWP*W*P + NWR*W*R) +(RHO/2)*L**3*(NV* & -U*V + NVW*V*W +-NDR*U**2*D R) +-YAW + (XG*WEIGHT- &XB

The Effect of Elevated CO2 and O3 on Soil Nitrogen Inputs and Losses in a Soybean Agroecosystem in Illinois

USDA-ARS?s Scientific Manuscript database

It has been found that elevated atmospheric carbon dioxide (eCO2) and tropospheric ozone (eO3) affect belowground microbial processes, including N transformations, through plant-mediated changes. Conversely, changes in soil organic carbon sequestration and plant biomass production are constrained by...

Computational modeling of dynamic alteration of plasma vitellogenin in response to aromatase CYP19 inhibition in fathead minnows

EPA Science Inventory

In vertebrates, conversion of testosterone into 17β-estradiol (E2) is catalyzed by cytochrome P450 (CYP) 19A aromatase. An important role of E2 in oviparous vertebrates such as fish is stimulation of hepatic synthesis of the glycolipoprotein vitellogenin (VTG), an egg yolk precur...

Kinetics of intercalation of lithium into NbSe3 and TiS2 cathodes

NASA Technical Reports Server (NTRS)

Ratnakumar, B. V.; Nagasubramanian, G.; Di Stefano, S.; Bankston, C. P.

1992-01-01

Titanium disulfide and niobium triselenide are two well-studied candidate materials for positive electrodes in rechargeable lithium cells. A comparative study of the kinetics of intercalation of lithium in both the cathodes is made here based on various electrochemical techniques, i.e., linear polarization, potentiodynamic polarization, and ac impedance under different experimental conditions such as prismatic or disk configuration of fresh, partially discharged, or cycled electrode. Further, the diffusion coefficients of lithium ions in these cathodes are estimated under these conditions using conventional techniques, i.e., ac impedance, chronocoulometry, chronoamperometry, and current pulse relaxation. Based on the values of the diffusion coefficients, the applicability of these methods for the determination of diffusion coefficients is discussed.

β-FeSi II as a Kankyo (environmentally friendly) semiconductor for solar cells in the space application

NASA Astrophysics Data System (ADS)

Makita, Yunosuke; Ootsuka, Teruhisa; Fukuzawa, Yasuhiro; Otogawa, Naotaka; Abe, Hironori; Liu, Zhengxin; Nakayama, Yasuhiko

2006-04-01

β-FeSi II defined as a Kankyo (Environmentally Friendly) semiconductor is regarded as one of the 3-rd generation semiconductors after Si and GaAs. Versatile features about β-FeSi II are, i) high optical absorption coefficient (>10 5cm -1), ii) chemical stability at temperatures as high as 937°C, iii) high thermoelectric power (Seebeck coefficient of k ~ 10 -4/K), iv) a direct energy band-gap of 0.85 eV, corresponding to 1.5μm of quartz optical fiber communication, v) lattice constant nearly well-matched to Si substrate, vi) high resistance against the humidity, chemical attacks and oxidization. Using β-FeSi II films, one can fabricate various devices such as Si photosensors, solar cells and thermoelectric generators that can be integrated basically on Si-LSI circuits. β-FeSi II has high resistance against the exposition of cosmic rays and radioactive rays owing to the large electron-empty space existing in the electron cloud pertinent to β-FeSi II. Further, the specific gravity of β-FeSi II (4.93) is placed between Si (2.33) and GaAs ((5.33). These features together with the aforementioned high optical absorption coefficient are ideal for the fabrication of solar cells to be used in the space. To demonstrate fascinating capabilities of β-FeSi II, one has to prepare high quality β-FeSi II films. We in this report summarize the current status of β-FeSi II film preparation technologies. Modified MBE and facing-target sputtering (FTS) methods are principally discussed. High quality β-FeSi II films have been formed on Si substrates by these methods. Preliminary structures of n-β-FeSi II /p-Si and p-β-FeSi II /n-Si solar cells indicated an energy conversion efficiency of 3.7%, implying that β-FeSi II is practically a promising semiconductor for a photovoltaic device.

Tuning Bandgap of p-Type Cu2Zn(Sn, Ge)(S, Se)4 Semiconductor Thin Films via Aqueous Polymer-Assisted Deposition.

PubMed

Yi, Qinghua; Wu, Jiang; Zhao, Jie; Wang, Hao; Hu, Jiapeng; Dai, Xiao; Zou, Guifu

2017-01-18

Bandgap engineering of kesterite Cu 2 Zn(Sn, Ge)(S, Se) 4 with well-controlled stoichiometric composition plays a critical role in sustainable inorganic photovoltaics. Herein, a cost-effective and reproducible aqueous solution-based polymer-assisted deposition approach is developed to grow p-type Cu 2 Zn(Sn, Ge)(S, Se) 4 thin films with tunable bandgap. The bandgap of Cu 2 Zn(Sn, Ge)(S, Se) 4 thin films can be tuned within the range 1.05-1.95 eV using the aqueous polymer-assisted deposition by accurately controlling the elemental compositions. One of the as-grown Cu 2 Zn(Sn, Ge)(S, Se) 4 thin films exhibits a hall coefficient of +137 cm 3 /C. The resistivity, concentration and carrier mobility of the Cu 2 ZnSn(S, Se) 4 thin film are 3.17 ohm·cm, 4.5 × 10 16 cm -3 , and 43 cm 2 /(V·S) at room temperature, respectively. Moreover, the Cu 2 ZnSn(S, Se) 4 thin film when used as an active layer in a solar cell leads to a power conversion efficiency of 3.55%. The facile growth of Cu 2 Zn(Sn, Ge)(S, Se) 4 thin films in an aqueous system, instead of organic solvents, provides great promise as an environmental-friendly platform to fabricate a variety of single/multi metal chalcogenides for the thin film industry and solution-processed photovoltaic devices.

Molecular Modeling on Berberine Derivatives toward BuChE: An Integrated Study with Quantitative Structure-Activity Relationships Models, Molecular Docking, and Molecular Dynamics Simulations.

PubMed

Fang, Jiansong; Pang, Xiaocong; Wu, Ping; Yan, Rong; Gao, Li; Li, Chao; Lian, Wenwen; Wang, Qi; Liu, Ai-lin; Du, Guan-hua

2016-05-01

A dataset of 67 berberine derivatives for the inhibition of butyrylcholinesterase (BuChE) was studied based on the combination of quantitative structure-activity relationships models, molecular docking, and molecular dynamics methods. First, a series of berberine derivatives were reported, and their inhibitory activities toward butyrylcholinesterase (BuChE) were evaluated. By 2D- quantitative structure-activity relationships studies, the best model built by partial least-square had a conventional correlation coefficient of the training set (R(2)) of 0.883, a cross-validation correlation coefficient (Qcv2) of 0.777, and a conventional correlation coefficient of the test set (Rpred2) of 0.775. The model was also confirmed by Y-randomization examination. In addition, the molecular docking and molecular dynamics simulation were performed to better elucidate the inhibitory mechanism of three typical berberine derivatives (berberine, C2, and C55) toward BuChE. The predicted binding free energy results were consistent with the experimental data and showed that the van der Waals energy term (ΔEvdw) difference played the most important role in differentiating the activity among the three inhibitors (berberine, C2, and C55). The developed quantitative structure-activity relationships models provide details on the fine relationship linking structure and activity and offer clues for structural modifications, and the molecular simulation helps to understand the inhibitory mechanism of the three typical inhibitors. In conclusion, the results of this study provide useful clues for new drug design and discovery of BuChE inhibitors from berberine derivatives. © 2015 John Wiley & Sons A/S.

COMPILATION OF CONVERSION COEFFICIENTS FOR THE DOSE TO THE LENS OF THE EYE.

PubMed

Behrens, R

2017-04-28

A compilation of fluence-to-absorbed dose conversion coefficients for the dose to the lens of the eye is presented. The compilation consists of both previously published data and newly calculated values: photon data (5 keV-50 MeV for both kerma approximation and full electron transport), electron data (10 keV-50 MeV), and positron data (1 keV-50 MeV) - neutron data will be published separately. Values are given for angles of incidence from 0° up to 90° in steps of 15° and for rotational irradiation. The data presented can be downloaded from this article's website and they are ready for use by Report Committee (RC) 26. This committee has been set up by the International Commission on Radiation Units and Measurements (ICRU) and is working on a 'proposal for a redefinition of the operational quantities for external radiation exposure'. © The Author 2016. Published by Oxford University Press.

Hybrid local piezoelectric and conductive functions for high performance airborne sound absorption

NASA Astrophysics Data System (ADS)

Rahimabady, Mojtaba; Statharas, Eleftherios Christos; Yao, Kui; Sharifzadeh Mirshekarloo, Meysam; Chen, Shuting; Tay, Francis Eng Hock

2017-12-01

A concept of hybrid local piezoelectric and electrical conductive functions for improving airborne sound absorption is proposed and demonstrated in composite foam made of porous polar polyvinylidene fluoride (PVDF) mixed with conductive single-walled carbon nanotube (SWCNT). According to our hybrid material function design, the local piezoelectric effect in the PVDF matrix with the polar structure and the electrical resistive loss of SWCNT enhanced sound energy conversion to electrical energy and subsequently to thermal energy, respectively, in addition to the other known sound absorption mechanisms in a porous material. It is found that the overall energy conversion and hence the sound absorption performance are maximized when the concentration of the SWCNT is around the conductivity percolation threshold. For the optimal composition of PVDF/5 wt. % SWCNT, a sound reduction coefficient of larger than 0.58 has been obtained, with a high sound absorption coefficient higher than 50% at 600 Hz, showing their great values for passive noise mitigation even at a low frequency.

Thermoelectric Properties of Complex Oxide Heterostructures

NASA Astrophysics Data System (ADS)

Cain, Tyler Andrew

Thermoelectrics are a promising energy conversion technology for power generation and cooling systems. The thermal and electrical properties of the materials at the heart of thermoelectric devices dictate conversion efficiency and technological viability. Studying the fundamental properties of potentially new thermoelectric materials is of great importance for improving device performance and understanding the electronic structure of materials systems. In this dissertation, investigations on the thermoelectric properties of a prototypical complex oxide, SrTiO3, are discussed. Hybrid molecular beam epitaxy (MBE) is used to synthesize La-doped SrTiO3 thin films, which exhibit high electron mobilities and large Seebeck coefficients resulting in large thermoelectric power factors at low temperatures. Large interfacial electron densities have been observed in SrTiO3/RTiO 3 (R=Gd,Sm) heterostructures. The thermoelectric properties of such heterostructures are investigated, including the use of a modulation doping approach to control interfacial electron densities. Low-temperature Seebeck coefficients of extreme electron-density SrTiO3 quantum wells are shown to provide insight into their electronic structure.

Monitoring on internal temperature of composite insulator with embedding fiber Bragg grating for early diagnosis

NASA Astrophysics Data System (ADS)

Chen, Wen; Tang, Ming

2017-04-01

The abnormal temperature rise is the precursor of the defective composite insulator in power transmission line. However no consolidated techniques or methodologies can on line monitor its internal temperature now. Thus a new method using embedding fiber Bragg grating (FBG) in fiber reinforced polymer (FRP) rod is adopted to monitor its internal temperature. To correctly demodulate the internal temperature of FRP rod from the Bragg wavelength shift of FBG, the conversion coefficient between them is deduced theoretically based on comprehensive investigation on the thermal stresses of the metal-composite joint, as well as its material and structural properties. Theoretical model shows that the conversion coefficients of FBG embedded in different positions will be different because of non-uniform thermal stress distribution, which is verified by an experiment. This work lays the theoretical foundation of monitoring the internal temperature of composite insulator with embedding FBG, which is of great importance to its health structural monitoring, especially early diagnosis.

Estimation of Knudsen diffusion coefficients from tracer experiments conducted with a binary gas system and a porous medium.

PubMed

Hibi, Yoshihiko; Kashihara, Ayumi

2018-03-01

A previous study has reported that Knudsen diffusion coefficients obtained by tracer experiments conducted with a binary gas system and a porous medium are consistently smaller than those obtained by permeability experiments conducted with a single-gas system and a porous medium. To date, however, that study is the only one in which tracer experiments have been conducted with a binary gas system. Therefore, to confirm this difference in Knudsen diffusion coefficients, we used a method we had developed previously to conduct tracer experiments with a binary carbon dioxide-nitrogen gas system and five porous media with permeability coefficients ranging from 10 -13 to 10 -11  m 2 . The results showed that the Knudsen diffusion coefficient of N 2 (D N2 ) (cm 2 /s) was related to the effective permeability coefficient k e (m 2 ) as D N2  = 7.39 × 10 7 k e 0.767 . Thus, the Knudsen diffusion coefficients of N 2 obtained by our tracer experiments were consistently 1/27 of those obtained by permeability experiments conducted with many porous media and air by other researchers. By using an inversion simulation to fit the advection-diffusion equation to the distribution of concentrations at observation points calculated by mathematically solving the equation, we confirmed that the method used to obtain the Knudsen diffusion coefficient in this study yielded accurate values. Moreover, because the Knudsen diffusion coefficient did not differ when columns with two different lengths, 900 and 1500 mm, were used, this column property did not influence the flow of gas in the column. The equation of the dusty gas model already includes obstruction factors for Knudsen diffusion and molecular diffusion, which relate to medium heterogeneity and tortuosity and depend only on the structure of the porous medium. Furthermore, there is no need to take account of any additional correction factor for molecular diffusion except the obstruction factor because molecular diffusion is only treated in a multicomponent gas system. Thus, molecular diffusion considers only the obstruction factor related to tortuosity. Therefore, we introduced a correction factor for a multicomponent gas system into the DGM equation, multiplying the Knudsen diffusion coefficient, which includes the obstruction factor related to tortuosity, by this correction factor. From the present experimental results, the value of this correction factor was 1/27, and it depended only on the structure of the gas system in the porous medium. Copyright © 2018 Elsevier B.V. All rights reserved.

Prediction of the critical reduced electric field strength for carbon dioxide and its mixtures with copper vapor from Boltzmann analysis for a gas temperature range of 300 K to 4000 K at 0.4 MPa

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Xingwen, E-mail: xwli@mail.xjtu.edu.cn; Guo, Xiaoxue; Zhao, Hu

2015-04-14

The influence of copper vapor mixed in hot CO{sub 2} on dielectric breakdown properties of gas mixture at a fixed pressure of 0.4 MPa for a temperature range of 300 K–4000 K is numerically analyzed. First, the equilibrium composition of hot CO{sub 2} with different copper fractions is calculated using a method based on mass action law. The next stage is devoted to computing the electron energy distribution functions (EEDF) by solving the two-term Boltzmann equation. The reduced ionization coefficient, the reduced attachment coefficient, and the reduced effective ionization coefficient are then obtained based on the EEDF. Finally, the critical reduced electric fieldmore » (E/N){sub cr} is obtained. The results indicate that an increasing mole fraction of copper markedly reduces (E/N){sub cr} of the CO{sub 2}–Cu gas mixtures because of copper's low ionization potential and large ionization cross section. Additionally, the generation of O{sub 2} from the thermal dissociation of CO{sub 2} contributes to the increase of (E/N){sub cr} of CO{sub 2}–Cu hot gas mixtures from about 2000 K to 3500 K.« less

Thermo-optical properties of Alexandrite laser crystal

NASA Astrophysics Data System (ADS)

Loiko, Pavel; Ghanbari, Shirin; Matrosov, Vladimir; Yumashev, Konstantin; Major, Arkady

2018-02-01

Alexandrite is a well-known material for broadly tunable and power-scalable near-IR lasers. We measured the thermal coefficients of the optical path (TCOP) and thermo-optic coefficients (TOCs) of Alexandrite at 632.8 nm for three principal light polarizations, E || a, E || b and E || c. All TOCs are positive and show a notable polarization-anisotropy, dna/dT = 5.5, dnb/dT = 7.0 and dnc/dT = 14.9×10-6 K-1. We also characterized thermal lensing in a continuous-wave Alexandrite laser which used a Brewster-oriented c-cut 0.16 at.% Cr3+ doped BeAl2O4 crystal pumped at 532 nm and emitted at 750.9 nm (E || b). The measured thermal lens was positive and astigmatic. The sensitivity factors of the thermal lens (Mx,y = dDx,y/dPabs) were found to be Mx = 1.74 and My = 2.38 [m-1/W].

Auditory Time-Frequency Masking for Spectrally and Temporally Maximally-Compact Stimuli

PubMed Central

Laback, Bernhard; Savel, Sophie; Ystad, Sølvi; Balazs, Peter; Meunier, Sabine; Kronland-Martinet, Richard

2016-01-01

Many audio applications perform perception-based time-frequency (TF) analysis by decomposing sounds into a set of functions with good TF localization (i.e. with a small essential support in the TF domain) using TF transforms and applying psychoacoustic models of auditory masking to the transform coefficients. To accurately predict masking interactions between coefficients, the TF properties of the model should match those of the transform. This involves having masking data for stimuli with good TF localization. However, little is known about TF masking for mathematically well-localized signals. Most existing masking studies used stimuli that are broad in time and/or frequency and few studies involved TF conditions. Consequently, the present study had two goals. The first was to collect TF masking data for well-localized stimuli in humans. Masker and target were 10-ms Gaussian-shaped sinusoids with a bandwidth of approximately one critical band. The overall pattern of results is qualitatively similar to existing data for long maskers. To facilitate implementation in audio processing algorithms, a dataset provides the measured TF masking function. The second goal was to assess the potential effect of auditory efferents on TF masking using a modeling approach. The temporal window model of masking was used to predict present and existing data in two configurations: (1) with standard model parameters (i.e. without efferents), (2) with cochlear gain reduction to simulate the activation of efferents. The ability of the model to predict the present data was quite good with the standard configuration but highly degraded with gain reduction. Conversely, the ability of the model to predict existing data for long maskers was better with than without gain reduction. Overall, the model predictions suggest that TF masking can be affected by efferent (or other) effects that reduce cochlear gain. Such effects were avoided in the experiment of this study by using maximally-compact stimuli. PMID:27875575

Auditory Time-Frequency Masking for Spectrally and Temporally Maximally-Compact Stimuli.

PubMed

Necciari, Thibaud; Laback, Bernhard; Savel, Sophie; Ystad, Sølvi; Balazs, Peter; Meunier, Sabine; Kronland-Martinet, Richard

2016-01-01

Many audio applications perform perception-based time-frequency (TF) analysis by decomposing sounds into a set of functions with good TF localization (i.e. with a small essential support in the TF domain) using TF transforms and applying psychoacoustic models of auditory masking to the transform coefficients. To accurately predict masking interactions between coefficients, the TF properties of the model should match those of the transform. This involves having masking data for stimuli with good TF localization. However, little is known about TF masking for mathematically well-localized signals. Most existing masking studies used stimuli that are broad in time and/or frequency and few studies involved TF conditions. Consequently, the present study had two goals. The first was to collect TF masking data for well-localized stimuli in humans. Masker and target were 10-ms Gaussian-shaped sinusoids with a bandwidth of approximately one critical band. The overall pattern of results is qualitatively similar to existing data for long maskers. To facilitate implementation in audio processing algorithms, a dataset provides the measured TF masking function. The second goal was to assess the potential effect of auditory efferents on TF masking using a modeling approach. The temporal window model of masking was used to predict present and existing data in two configurations: (1) with standard model parameters (i.e. without efferents), (2) with cochlear gain reduction to simulate the activation of efferents. The ability of the model to predict the present data was quite good with the standard configuration but highly degraded with gain reduction. Conversely, the ability of the model to predict existing data for long maskers was better with than without gain reduction. Overall, the model predictions suggest that TF masking can be affected by efferent (or other) effects that reduce cochlear gain. Such effects were avoided in the experiment of this study by using maximally-compact stimuli.

When Partial Nephrectomy is Unsuccessful: Understanding the Reasons for Conversion from Robotic Partial to Radical Nephrectomy at a Tertiary Referral Center.

PubMed

Kara, Önder; Maurice, Matthew J; Mouracade, Pascal; Malkoç, Ercan; Dagenais, Julien; Nelson, Ryan J; Chavali, Jaya Sai S; Stein, Robert J; Fergany, Amr; Kaouk, Jihad H

2017-07-01

We sought to identify the preoperative factors associated with conversion from robotic partial nephrectomy to radical nephrectomy. We report the incidence of this event. Using our institutional review board approved database, we abstracted data on 1,023 robotic partial nephrectomies performed at our center between 2010 and 2015. Standard and converted cases were compared in terms of patients and tumor characteristics, and perioperative, functional and oncologic outcomes. Logistic regression analysis was done to identify predictors of radical conversion. The overall conversion rate was 3.1% (32 of 1,023 cases). The most common reasons for conversion were tumor involvement of hilar structures (8 cases or 25%), failure to achieve negative margins on frozen section (7 or 21.8%), suspicion of advanced disease (5 or 15.6%) and failure to progress (5 or 15.6%). Patients requiring conversion were older and had a higher Charlson score (both p <0.01), including an increased prevalence of chronic kidney disease (p = 0.02). Increasing tumor size (5 vs 3.1 cm, p <0.01) and R.E.N.A.L. (radius, exophytic/endophytic properties, nearness of tumor to collecting system or sinus, anterior/posterior, location relative to polar lines and hilar location) score (9 vs 8, p <0.01) were also associated with an increased risk of conversion. Worse baseline renal function (OR 0.98, 95% CI 0.96-0.99, p = 0.04), large tumor size (OR 1.44, 95% CI 1.22-1.7, p <0.01) and increasing R.E.N.A.L. score (p = 0.02) were independent predictors of conversion. Compared to converted cases, at latest followup standard robotic partial nephrectomy cases had similar short-term oncologic outcomes but better renal functional preservation (p <0.01). At a high volume center the rate of robotic partial nephrectomy conversion to radical nephrectomy was 3.1%, including 2.2% of preoperatively anticipated nephrectomy cases. Increasing tumor size and complexity, and poor preoperative renal function are the main predictors of conversion. Copyright © 2017 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Medium-Term Renal Function in a Large Cohort of Stable Kidney Transplant Recipients Converted From Twice-Daily to Once-Daily Tacrolimus.

PubMed

Guirado, Lluís; Burgos, Dolores; Cantarell, Carme; Fernández, Ana; Franco, Antonio; Gentil, Miguel Ángel; Mazuecos, Auxiliadora; Torregrosa, Josep Vicenç; Huertas, Ernesto Gómez; Ruiz, Juan Carlos; Plumed, Jaime Sánchez; Paul, Javier; Lauzurica, Ricardo; Zárraga, Sofía; Osuna, Antonio; Jiménez, Carlos; Alonso, Ángel; Rodríguez, Alberto; Bardají, Beatriz; Hernández, Domingo

2015-08-01

There is some evidence pointing toward better renal function in kidney transplant recipients (KTR) treated with once-daily tacrolimus (QD-TAC) vs. twice-daily tacrolimus (BID-TAC). This is an extension study of a 1-year, single arm prospective study of stable KTR who were converted from BID-TAC to QD-TAC (4.9 ± 4.0 years after transplantation) in Spanish routine clinical practice. Patient and graft survival, renal function, acute rejection episodes, and other analytic parameters were assessed at 24 and 36 months after conversion. A total of 1798 KTR were included in the extension study. Tacrolimus doses at 36 months were significantly lower compared to those at time of conversion (-0.2 mg/day; P = 0.023). Blood levels were lower than baseline during all the study (P < 0.001). Graft and patient survival at 3 years after conversion were 93.9% and 95.1%, respectively. Compared with baseline, the mean estimated glomerular filtration rate (eGFR) remained very stable at all timepoints (56.7 ± 19.8 vs 58.1 ± 24.6 mL/min per 1.73 m(2) at month 36; P = 0.623). Even when patients reinitiating dialysis were counted as eGFR = 0, the mean eGFR was very stable. In fact, a small but significant increase was observed at 36 months versus baseline (+0.1 mL/min per 1.73 m(2); P = 0.025). An increase in proteinuria was observed at 36 months versus baseline (+0.11 g/24 h; P < 0.001). Acute rejection rates were low during the study. Conversion from BID-TAC to QD-TAC in a large cohort of stable KTR was safe and associated with a very stable renal function after 3 years. Comparative studies are warranted to assess the feasibility of such conversion.

Medium-Term Renal Function in a Large Cohort of Stable Kidney Transplant Recipients Converted From Twice-Daily to Once-Daily Tacrolimus

PubMed Central

Guirado, Lluís; Burgos, Dolores; Cantarell, Carme; Fernández, Ana; Franco, Antonio; Gentil, Miguel Ángel; Mazuecos, Auxiliadora; Torregrosa, Josep Vicenç; Huertas, Ernesto Gómez; Ruiz, Juan Carlos; Plumed, Jaime Sánchez; Paul, Javier; Lauzurica, Ricardo; Zárraga, Sofía; Osuna, Antonio; Jiménez, Carlos; Alonso, Ángel; Rodríguez, Alberto; Bardají, Beatriz; Hernández, Domingo

2015-01-01

Background There is some evidence pointing toward better renal function in kidney transplant recipients (KTR) treated with once-daily tacrolimus (QD-TAC) vs. twice-daily tacrolimus (BID-TAC). Methods This is an extension study of a 1-year, single arm prospective study of stable KTR who were converted from BID-TAC to QD-TAC (4.9 ± 4.0 years after transplantation) in Spanish routine clinical practice. Patient and graft survival, renal function, acute rejection episodes, and other analytic parameters were assessed at 24 and 36 months after conversion. Results A total of 1798 KTR were included in the extension study. Tacrolimus doses at 36 months were significantly lower compared to those at time of conversion (−0.2 mg/day; P = 0.023). Blood levels were lower than baseline during all the study (P < 0.001). Graft and patient survival at 3 years after conversion were 93.9% and 95.1%, respectively. Compared with baseline, the mean estimated glomerular filtration rate (eGFR) remained very stable at all timepoints (56.7 ± 19.8 vs 58.1 ± 24.6 mL/min per 1.73 m2 at month 36; P = 0.623). Even when patients reinitiating dialysis were counted as eGFR = 0, the mean eGFR was very stable. In fact, a small but significant increase was observed at 36 months versus baseline (+0.1 mL/min per 1.73 m2; P = 0.025). An increase in proteinuria was observed at 36 months versus baseline (+0.11 g/24 h; P < 0.001). Acute rejection rates were low during the study. Conclusions Conversion from BID-TAC to QD-TAC in a large cohort of stable KTR was safe and associated with a very stable renal function after 3 years. Comparative studies are warranted to assess the feasibility of such conversion. PMID:27500226

Second order sliding mode control for a quadrotor UAV.

PubMed

Zheng, En-Hui; Xiong, Jing-Jing; Luo, Ji-Liang

2014-07-01

A method based on second order sliding mode control (2-SMC) is proposed to design controllers for a small quadrotor UAV. For the switching sliding manifold design, the selection of the coefficients of the switching sliding manifold is in general a sophisticated issue because the coefficients are nonlinear. In this work, in order to perform the position and attitude tracking control of the quadrotor perfectly, the dynamical model of the quadrotor is divided into two subsystems, i.e., a fully actuated subsystem and an underactuated subsystem. For the former, a sliding manifold is defined by combining the position and velocity tracking errors of one state variable, i.e., the sliding manifold has two coefficients. For the latter, a sliding manifold is constructed via a linear combination of position and velocity tracking errors of two state variables, i.e., the sliding manifold has four coefficients. In order to further obtain the nonlinear coefficients of the sliding manifold, Hurwitz stability analysis is used to the solving process. In addition, the flight controllers are derived by using Lyapunov theory, which guarantees that all system state trajectories reach and stay on the sliding surfaces. Extensive simulation results are given to illustrate the effectiveness of the proposed control method. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

Measurement of the high-temperature Seebeck coefficient of thin films by means of an epitaxially regrown thermometric reference material.

PubMed

Ramu, Ashok T; Mages, Phillip; Zhang, Chong; Imamura, Jeffrey T; Bowers, John E

2012-09-01

The Seebeck coefficient of a typical thermoelectric material, silicon-doped InGaAs lattice-matched to InP, is measured over a temperature range from 300 K to 550 K. By depositing and patterning a thermometric reference bar of silicon-doped InP adjacent to a bar of the material under test, temperature differences are measured directly. This is in contrast to conventional two-thermocouple techniques that subtract two large temperatures to yield a small temperature difference, a procedure prone to errors. The proposed technique retains the simple instrumentation of two-thermocouple techniques while eliminating the critical dependence of the latter on good thermal contact. The repeatability of the proposed technique is demonstrated to be ±2.6% over three temperature sweeps, while the repeatability of two-thermocouple measurements is about ±5%. The improved repeatability is significant for reliable reporting of the ZT figure of merit, which is proportional to the square of the Seebeck coefficient. The accuracy of the proposed technique depends on the accuracy with which the high-temperature Seebeck coefficient of the reference material may be computed or measured. In this work, the Seebeck coefficient of the reference material, n+ InP, is computed by rigorous solution of the Boltzmann transport equation. The accuracy and repeatability of the proposed technique can be systematically improved by scaling, and the method is easily extensible to other material systems currently being investigated for high thermoelectric energy conversion efficiency.

Conversion of estrone to estradiol in male fathead minnows: Implications for assessing risk

EPA Science Inventory

Estrogens are frequently observed in aquatic environments associated with anthropogenic influence, such as agricultural runoff and wastewater treatment effluent. While 17â-estradiol (E2) is the most potent naturally-occurring estrogen, estrone (E1) is often found at higher ...

Potentialities of silicon nanowire forests for thermoelectric generation

NASA Astrophysics Data System (ADS)

Dimaggio, Elisabetta; Pennelli, Giovanni

2018-04-01

Silicon is a material with very good thermoelectric properties, with regard to Seebeck coefficient and electrical conductivity. Low thermal conductivities, and hence high thermal to electrical conversion efficiencies, can be achieved in nanostructures, which are smaller than the phonon mean free path but large enough to preserve the electrical conductivity. We demonstrate that it is possible to fabricate a leg of a thermoelectric generator based on large collections of long nanowires, placed perpendicularly to the two faces of a silicon wafer. The process exploits the metal assisted etching technique which is simple, low cost, and can be easily applied to large surfaces. Copper can be deposited by electrodeposition on both faces, so that contacts can be provided, on top of the nanowires. Thermal conductivity of silicon nanowire forests with more than 107 nanowires mm-2 have been measured; the result is comparable with that achieved by several groups on devices based on few nanowires. On the basis of the measured parameters, numerical calculations of the efficiency of silicon-based thermoelectric generators are reported, and the potentialities of these devices for thermal to electrical energy conversion are shown. Criteria to improve the conversion efficiency are suggested and described.

Influence of speech sample on perceptual rating of hypernasality.

PubMed

Medeiros, Maria Natália Leite de; Fukushiro, Ana Paula; Yamashita, Renata Paciello

2016-07-07

To investigate the influence of speech sample of spontaneous conversation or sentences repetition on intra and inter-rater hypernasality reliability. One hundred and twenty audio recorded speech samples (60 containing spontaneous conversation and 60 containing repeated sentences) of individuals with repaired cleft palate±lip, both genders, aged between 6 and 52 years old (mean=21±10) were selected and edited. Three experienced speech and language pathologists rated hypernasality according to their own criteria using 4-point scale: 1=absence of hypernasality, 2=mild hypernasality, 3=moderate hypernasality and 4=severe hypernasality, first in spontaneous speech samples and 30 days after, in sentences repetition samples. Intra- and inter-rater agreements were calculated for both speech samples and were statistically compared by the Z test at a significance level of 5%. Comparison of intra-rater agreements between both speech samples showed an increase of the coefficients obtained in the analysis of sentences repetition compared to those obtained in spontaneous conversation. Comparison between inter-rater agreement showed no significant difference among the three raters for the two speech samples. Sentences repetition improved intra-raters reliability of perceptual judgment of hypernasality. However, the speech sample had no influence on reliability among different raters.

Nanostructured Solar Irradiation Control Materials for Solar Energy Conversion

NASA Technical Reports Server (NTRS)

Kang, Jinho; Marshall, I. A.; Torrico, M. N.; Taylor, C. R.; Ely, Jeffry; Henderson, Angel Z.; Kim, J.-W.; Sauti, G.; Gibbons, L. J.; Park, C.;

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weese, R K; Burnham, A K; Maienschein, J L

Dimensional changes related to temperature cycling of the beta and delta polymorphs of HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) are important for a variety of applications. The coefficient of thermal expansion (CTE) of the beta and delta phases are measured and reported in this work over a temperature range of -20 C to 215 C. In addition, dimensional changes associated with the phase transition were measured, both through the transition and back down. Initially, differential scanning calorimetry (DSC) was used to investigate back conversion of the delta phase to the beta phase polymorph. The most successful approach was first to measure the amount ofmore » the beta to delta conversion, then after a given cooling period a repeat analysis, to measure the heat consumed by a second pass through the beta to delta phase transition. In addition, TMA is used to measure the dimensional change of a 0.20-gram sample of HMX during its initial heating and then three days later during a 2nd heating. This HMX shows the beta to delta phase transition a second time, thereby confirming the back conversion from delta to beta phase HMX.« less

Voltammetry and Coulometry with Immersed Thin Layer Electrodes. Part 2. Practical Considerations and Experimental Results.

DTIC Science & Technology

1984-11-28

indicated by Popov and Geske (8), are: 31 - 2e- 13 and 213 - 2e : 312 [2) N Figure 8 is a plot of the charge required for complete conversion of the -I...and D.H. Geske , J. Amer. Chem. Soc. 80, 1340 (1958). 9. F.C. Anson, Anal. Chem. 38, 54 (1966). -4.. ; ’ : /) /" ’O"- ’,, FIGURE LEGENDS Figure 1

Models for Predicting the Biomass of Cunninghamialanceolata Trees and Stands in Southeastern China

PubMed Central

Saeed, Sajjad

2017-01-01

Using existing equations to estimate the biomass of a single tree or a forest stand still involves large uncertainties. In this study, we developed individual-tree biomass models for Chinese Fir (Cunninghamia lanceolata.) stands in Fujian Province, southeast China, by using 74 previously established models that have been most commonly used to estimate tree biomass. We selected the best fit models and modified them. The results showed that the published model ln(B(Biomass)) = a + b * ln(D) + c * (ln(H))2 + d * (ln(H))3 + e * ln(WD) had the best fit for estimating the tree biomass of Chinese Fir stands. Furthermore, we observed that variables D(diameter at breast height), H (height), and WD(wood density)were significantly correlated with the total tree biomass estimation model. As a result, a natural logarithm structure gave the best estimates for the tree biomass structure. Finally, when a multi-step improvement on tree biomass model was performed, the tree biomass model with Tree volume(TV), WD and biomass wood density conversion factor (BECF),achieved the highest simulation accuracy, expressed as ln(TB) = −0.0703 + 0.9780 * ln(TV) + 0.0213 * ln(WD) + 1.0166 * ln(BECF). Therefore, when TV, WD and BECF were combined with tree biomass volume coefficient bi for Chinese Fir, the stand biomass (SB)model included both volume(SV) and coefficient bi variables of the stand as follows: bi = Exp(−0.0703+0.9780*ln(TV)+0.0213 * ln(WD)+1.0166*ln(BECF)). The stand biomass model is SB = SV/TV * bi. PMID:28095512

Models for Predicting the Biomass of Cunninghamialanceolata Trees and Stands in Southeastern China.

PubMed

Guangyi, Mei; Yujun, Sun; Saeed, Sajjad

2017-01-01

Using existing equations to estimate the biomass of a single tree or a forest stand still involves large uncertainties. In this study, we developed individual-tree biomass models for Chinese Fir (Cunninghamia lanceolata.) stands in Fujian Province, southeast China, by using 74 previously established models that have been most commonly used to estimate tree biomass. We selected the best fit models and modified them. The results showed that the published model ln(B(Biomass)) = a + b * ln(D) + c * (ln(H))2 + d * (ln(H))3 + e * ln(WD) had the best fit for estimating the tree biomass of Chinese Fir stands. Furthermore, we observed that variables D(diameter at breast height), H (height), and WD(wood density)were significantly correlated with the total tree biomass estimation model. As a result, a natural logarithm structure gave the best estimates for the tree biomass structure. Finally, when a multi-step improvement on tree biomass model was performed, the tree biomass model with Tree volume(TV), WD and biomass wood density conversion factor (BECF),achieved the highest simulation accuracy, expressed as ln(TB) = -0.0703 + 0.9780 * ln(TV) + 0.0213 * ln(WD) + 1.0166 * ln(BECF). Therefore, when TV, WD and BECF were combined with tree biomass volume coefficient bi for Chinese Fir, the stand biomass (SB)model included both volume(SV) and coefficient bi variables of the stand as follows: bi = Exp(-0.0703+0.9780*ln(TV)+0.0213 * ln(WD)+1.0166*ln(BECF)). The stand biomass model is SB = SV/TV * bi.

Social conversational skills development in early implanted children.

PubMed

Guerzoni, Letizia; Murri, Alessandra; Fabrizi, Enrico; Nicastri, Maria; Mancini, Patrizia; Cuda, Domenico

2016-09-01

Social conversational skills are a salient aspect of early pragmatic development in young children. These skills include two different abilities, assertiveness and responsiveness. This study investigated the development of these abilities in early implanted children and their relationships with lexical development and some language-sensitive variables. Prospective, observational, nonrandomized study. Participants included 28 children with congenital profound sensorineural hearing loss. The mean age at device activation was 13.3 months (standard deviation [SD] ±4.2). The Social-Conversational Skills Rating Scale was used to evaluate assertiveness and responsiveness. The MacArthur-Bates Communicative Development Inventory (Words and Sentences form) was used to analyze the lexical development. The device experience was 12 months for each child, and the mean age at testing was 25.9 months (SD ±4.6). Assertiveness and responsiveness scores were within the normal range of normal-hearing age-matched peers. Age at cochlear implant activation exerted a significant impact, with the highest scores associated to the youngest patients. The residual correlations between assertiveness and responsiveness with the lexical development were positive and strongly significant (r = 0.69 and 0.73, respectively). Preoperative hearing threshold demonstrated an associated significant coefficient on the assertiveness score. Age at diagnosis and maternal education level were not correlated with the social conversational skills. Early-implanted children developed social conversational skills that are similar to normal-hearing peers matched for age 1 year after device activation. Social conversational skills and lexical development were strongly correlated, but the present study design cannot specify the direction of this relationship. Children with better preoperative residual hearing exhibited better assertive ability. 4 Laryngoscope, 126:2098-2105, 2016. © 2015 The American Laryngological, Rhinological and Otological Society, Inc.

40 CFR 60.85 - Test methods and procedures.

Code of Federal Regulations, 2011 CFR

2011-07-01

... the following equation: E=(CQsd)/(PK) where: E=emission rate of acid mist or SO2 kg/metric ton (lb/ton... flow rate of the effluent gas, dscm/hr (dscf/hr). P=production rate of 100 percent H2SO4, metric ton/hr (ton/hr). K=conversion factor, 1000 g/kg (1.0 lb/lb). (2) Method 8 shall be used to determine the acid...

40 CFR 60.85 - Test methods and procedures.

Code of Federal Regulations, 2013 CFR

2013-07-01

... the following equation: E=(CQsd)/(PK) where: E=emission rate of acid mist or SO2 kg/metric ton (lb/ton... flow rate of the effluent gas, dscm/hr (dscf/hr). P=production rate of 100 percent H2SO4, metric ton/hr (ton/hr). K=conversion factor, 1000 g/kg (1.0 lb/lb). (2) Method 8 shall be used to determine the acid...

40 CFR 60.85 - Test methods and procedures.

Code of Federal Regulations, 2012 CFR

2012-07-01

... the following equation: E=(CQsd)/(PK) where: E=emission rate of acid mist or SO2 kg/metric ton (lb/ton... flow rate of the effluent gas, dscm/hr (dscf/hr). P=production rate of 100 percent H2SO4, metric ton/hr (ton/hr). K=conversion factor, 1000 g/kg (1.0 lb/lb). (2) Method 8 shall be used to determine the acid...

Statistical analysis of the electric energy production from photovoltaic conversion using mobile and fixed constructions

NASA Astrophysics Data System (ADS)

Bugała, Artur; Bednarek, Karol; Kasprzyk, Leszek; Tomczewski, Andrzej

2017-10-01

The paper presents the most representative - from the three-year measurement time period - characteristics of daily and monthly electricity production from a photovoltaic conversion using modules installed in a fixed and 2-axis tracking construction. Results are presented for selected summer, autumn, spring and winter days. Analyzed measuring stand is located on the roof of the Faculty of Electrical Engineering Poznan University of Technology building. The basic parameters of the statistical analysis like mean value, standard deviation, skewness, kurtosis, median, range, or coefficient of variation were used. It was found that the asymmetry factor can be useful in the analysis of the daily electricity production from a photovoltaic conversion. In order to determine the repeatability of monthly electricity production, occurring between the summer, and summer and winter months, a non-parametric Mann-Whitney U test was used as a statistical solution. In order to analyze the repeatability of daily peak hours, describing the largest value of the hourly electricity production, a non-parametric Kruskal-Wallis test was applied as an extension of the Mann-Whitney U test. Based on the analysis of the electric energy distribution from a prepared monitoring system it was found that traditional forecasting methods of the electricity production from a photovoltaic conversion, like multiple regression models, should not be the preferred methods of the analysis.

Theoretical Study of Electronic Structure and Thermoelectric Properties of Doped CuAlO2

NASA Astrophysics Data System (ADS)

Poopanya, P.; Yangthaisong, A.; Rattanapun, C.; Wichainchai, A.

2011-05-01

The doping level dependence of thermoelectric properties of delafossite CuAlO2 has been investigated in the constant scattering time ( τ) approximation, starting from the first principles of electronic structure. In particular, the lattice parameters and the energy band structure were calculated using the total energy plane-wave pseudopotential method. It was found that the lattice parameters of CuAlO2 are a = 2.802 Å and c = 16.704 Å, and the internal parameter is u = 0.1097. CuAlO2 has an indirect band gap of 2.17 eV and a direct gap of 3.31 eV. The calculated energy band structures were then used to calculate the electrical transport coefficients of CuAlO2. By considering the effects of doping level and temperature, it was found that the Seebeck coefficient S( T) increases with increasing acceptor doping ( A d) level. The values of S( T) in our experiments correspond to an A d level at 0.262 eV, which is identified as the Fermi level of CuAlO2. Based on our experimental Seebeck coefficient and the electrical conductivity, the constant relaxation time is estimated to be 1 × 10-16 s. The power factor is large for a low A d level and increases with temperature. It is suggested that delafossite CuAlO2 can be considered as a promising thermoelectric oxide material at high doping and high temperature.

Relocking of intrinsic angular momenta in collisions of diatoms with ions: Capture of H2(j = 0,1) by H2+

NASA Astrophysics Data System (ADS)

Dashevskaya, E. I.; Litvin, I.; Nikitin, E. E.; Troe, J.

2016-12-01

Rate coefficients for capture of H2(j = 0,1) by H2+ are calculated in perturbed rotor approximation, i.e., at collision energies considerably lower than Bhc (where B denotes the rotational constant of H2). The results are compared with the results from an axially nonadiabatic channel (ANC) approach, the latter providing a very good approximation from the low-temperature Bethe-Wigner to the high temperature Langevin limit. The classical ANC approximation performs satisfactorily at temperatures above 0.1 K. At 0.1 K, the rate coefficient for j =1 is about 25% higher than that for j = 0 while the latter is close to the Langevin rate coefficient. The Bethe-Wigner limit of the rate coefficient for j = 1 is about twice that for j = 0. The analysis of the relocking of the intrinsic angular momentum of H2 during the course of the collision illustrates the significance of relocking in capture dynamics in general.

[Prediction of soil adsorption coefficients of organic compounds in a wide range of soil types by soil column liquid chromatography].

PubMed

Guo, Rongbo; Chen, Jiping; Zhang, Qing; Wu, Wenzhong; Liang, Xinmiao

2004-01-01

Using the methanol-water mixtures as mobile phases of soil column liquid chromatography (SCLC), prediction of soil adsorption coefficients (K(d)) by SCLC was validated in a wide range of soil types. The correlations between the retention factors measured by SCLC and soil adsorption coefficients measured by batch experiments were studied for five soils with different properties, i.e., Eurosoil 1#, 2#, 3#, 4# and 5#. The results show that good correlations existed between the retention factors and soil adsorption coefficients for Eurosoil 1#, 2#, 3# and 4#. For Eurosoil 5# which has a pH value of near 3, the correlation between retention factors and soil adsorption coefficients was unsatisfactory using methanol-water as mobile phase of SCLC. However, a good correlation was obtained using a methanol-buffer mixture with pH 3 as the mobile phase. This study proved that the SCLC is suitable for the prediction of soil adsorption coefficients.

Radon diffusion coefficients in 360 waterproof materials of different chemical composition.

PubMed

Jiránek, M; Kotrbatá, M

2011-05-01

This paper summarises the results of radon diffusion coefficient measurements in 360 common waterproof materials available throughout Europe. The materials were grouped into 26 categories according to their chemical composition. It was found that the diffusion coefficients of materials used for protecting houses against radon vary within eight orders from 10(-15) to 10(-8) m(2) s(-1). The lowest values were obtained for bitumen membranes with an Al carrier film and for ethylene vinyl acetate membranes. The highest radon diffusion coefficient values were discovered for sodium bentonite membranes, rubber membranes made of ethylene propylene diene monomer and polymer cement coatings. The radon diffusion coefficients for waterproofings widely used for protecting houses, i.e. flexible polyvinyl chloride, high-, low-density polyethylene, polypropylene and bitumen membranes, vary in the range from 3 × 10(-12) to 3 × 10(-11) m(2) s(-1). Tests were performed which confirmed that the radon diffusion coefficient is also an effective tool for verifying the air-tightness of joints.

Nanoscale TiO2 and Fe2O3 Architectures for Solar Energy Conversion Schemes

NASA Astrophysics Data System (ADS)

Sedach, Pavel Anatolyvich

The direct conversion of sunlight into more useable forms of energy has the potential of alleviating the environmental and social problems associated with a dependence on fossil fuels. If solar energy is to be utilized en-masse, however, it must be inexpensive and widely available. In this vein, the focus of this thesis is on nanostructured materials relevant to solar energy conversion and storage. Specifically, this thesis describes the ambient sol-gel synthesis of titanium dioxide (Ti02) nanowires designed for enhanced charge-transfer in solar collection devices, and the synthesis of novel disordered metal-oxide (MOx) catalysts for water oxidation. The introductory chapter of this thesis gives an overview of the various approaches to solar energy conversion. Sol---gel reaction conditions that enable the growth of one-dimensional (1-D) anatase TiO2 nanostructures from fluorine-doped tin oxide (FTO) for photovoltaics (PVs) are described in the second chapter. The generation of these linear nanostructures in the absence of an external bias or template is achieved by using facile experimental conditions (e.g., acetic acid (HOAc) and titanium isopropoxide (Ti(OiPr)4) in anhydrous heptane). The procedure was developed by functionalizing base-treated substrates with Ti-oxide nucleation sites that serve as a foundation for the growth of linear Ti-oxide macromolecules, which upon calcination, render uniform films of randomly oriented anatase TiO2 nanowires. A systematic evaluation of how reaction conditions (e.g., solvent volume, stoichiometry of reagents, substrate base treatment) affect the generation of these TiO 2 films is presented. A photo-organic MO. deposition route (i.e., photochemical metal-organic deposition (PMOD)) used to deposit thin-films of amorphous iron oxide (a-Fe2O3) for water oxidation catalysis is detailed in third chapter. It is shown that the irradiation of a spin-coated metal-organic film produces a film of non-crystalline a-Fe203. It is shown that annealing at various temperatures produces a-Fe 2O3 films with variable electronic properties and catalytic activities in the context of water oxidation. The study revealed that a-Fe2O3 are superior water oxidation catalysts (WOCs) relative to crystalline forms produced by high temperature annealing of the thin-films. This research has important implications in the conversion of sunlight into electricity, and then into hydrogen fuels.

On Anholonomic Deformation, Geometry, and Differentiation

DTIC Science & Technology

2013-02-01

αβχ are not necessarily Levi - Civita connection coefficients). The vector cross product × obeys, for two vectors V and W and two covectors α and β , V...three-dimensional space. 2.2.5. Euclidean space. Let GAB(X ) = GA · GB be the metric tensor of the space. The Levi - Civita connection coefficients of GAB...curvature tensor of the Levi - Civita connection vanishes identically: G R A BCD = 2 ( ∂[B G A C]D + G A[B|E|G EC]D ) = 0. (43) In n

Hydrodynamic analysis and shape optimization for vertical axisymmetric wave energy converters

NASA Astrophysics Data System (ADS)

Zhang, Wan-chao; Liu, Heng-xu; Zhang, Liang; Zhang, Xue-wei

2016-12-01

The absorber is known to be vertical axisymmetric for a single-point wave energy converter (WEC). The shape of the wetted surface usually has a great influence on the absorber's hydrodynamic characteristics which are closely linked with the wave power conversion ability. For complex wetted surface, the hydrodynamic coefficients have been predicted traditionally by hydrodynamic software based on the BEM. However, for a systematic study of various parameters and geometries, they are too multifarious to generate so many models and data grids. This paper examines a semi-analytical method of decomposing the complex axisymmetric boundary into several ring-shaped and stepped surfaces based on the boundary discretization method (BDM) which overcomes the previous difficulties. In such case, by using the linear wave theory based on eigenfunction expansion matching method, the expressions of velocity potential in each domain, the added mass, radiation damping and wave excitation forces of the oscillating absorbers are obtained. The good astringency of the hydrodynamic coefficients and wave forces are obtained for various geometries when the discrete number reaches a certain value. The captured wave power for a same given draught and displacement for various geometries are calculated and compared. Numerical results show that the geometrical shape has great effect on the wave conversion performance of the absorber. For absorbers with the same outer radius and draught or displacement, the cylindrical type shows fantastic wave energy conversion ability at some given frequencies, while in the random sea wave, the parabolic and conical ones have better stabilization and applicability in wave power conversion.

800 Hours of Operational Experience from a 2 kW(sub e) Solar Dynamic System

NASA Technical Reports Server (NTRS)

Shaltens, Richard K.; Mason, Lee S.

1999-01-01

From December 1994 to September 1998, testing with a 2 kW(sub e) Solar Dynamic power system resulted in 33 individual tests, 886 hours of solar heating, and 783 hours of power generation. Power generation ranged from 400 watts to over 2 kW(sub e), and SD system efficiencies have been measured up to 17 per cent, during simulated low-Earth orbit operation. Further, the turbo-alternator-compressors successfully completed 100 start/stops on foil bearings. Operation was conducted in a large thermal/vacuum facility with a simulated Sun at the NASA Lewis Research Center. The Solar Dynamic system featured a closed Brayton conversion unit integrated with a solar heat receiver, which included thermal energy storage for continuous power output through a typical low-Earth orbit. Two power conversion units and three alternator configurations were used during testing. This paper will review the test program, provide operational and performance data, and review a number of technology issues.

Monte Carlo study on the imaging performance of powder Lu2SiO5:Ce phosphor screens under x-ray excitation: comparison with Gd2O2S:Tb screens.

PubMed

Liaparinos, Panagiotis F; Kandarakis, Ioannis S; Cavouras, Dionisis A; Delis, Harry B; Panayiotakis, George S

2007-05-01

Lu2SiO5: Ce (LSO) scintillator is a relatively new luminescent material which has been successfully applied in positron emission tomography systems. Since it has been recently commercially available in powder form, it could be of value to investigate its performance for use in x-ray projection imaging as both physical and scintillating properties indicate a promising material for such applications. In the present study, a custom and validated Monte Carlo simulation code was used in order to examine the performance of LSO, under diagnostic radiology (mammography and general radiography) conditions. The Monte Carlo code was based on a model using Mie scattering theory for the description of light attenuation. Imaging characteristics, related to image brightness, spatial resolution and noise of LSO screens were predicted using only physical parameters of the phosphor. The overall performance of LSO powder phosphor screens was investigated in terms of the: (i) quantum detection efficiency (ii) emitted K-characteristic radiation (iii) luminescence efficiency (iv) modulation transfer function (v) Swank factor and (vi) zero-frequency detective quantum efficiency [DQE(0)]. Results were compared to the traditional rare-earth Gd2O2S:Tb (GOS) phosphor material. The relative luminescence efficiency of LSO phosphor was found inferior to that of GOS. This is due to the lower intrinsic conversion efficiency of LSO (0.08 instead of 0.15 of GOS) and the relatively high light extinction coefficient mext of this phosphor (0.239 mircom(-1) instead of 0.218 /microm(-1) for GOS). However, the property of increased light extinction combined with the rather sharp angular distribution of scattered light photons (anisotropy factor g=0.624 for LSO instead of 0.494 for GOS) reduce lateral light spreading and improve spatial resolution. In addition, LSO screens were found to exhibit better x-ray absorption as well as higher signal to noise transfer properties in the energy range from 18 keV up to 50.2 keV (e.g. DQE(0)=0.62 at 18 keV and for 34 mg/cm2, instead of 0.58 for GOS). The results indicate that certain optical properties of LSO (optical extinction coefficient, scattering anisotropy factor) combined with the relatively high x-ray coefficients, make this material a promising phosphor which, under appropriate conditions, could be considered for use in x-ray projection imaging detectors.

Effect of the SiO2 Support on the Catalytic Performance of Ag/ZrO2/SiO2 Catalysts for the Single-Bed Production of Butadiene from Ethanol

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dagle, Vanessa; Flake, Matthew D.; Lemmon, Teresa

2018-05-18

A ternary Ag/ZrO2/SiO2 catalyst system was studied for the single-step conversion of ethanol to butadiene by varying the catalyst composition (Ag, Ir, or Pt metal component, Ag/ZrO2 loading, and choice of SiO2 support) and operating conditions (space velocity and feed gas composition). Exceptional catalytic performance was achieved over a 1%Ag/4%ZrO2/SiO2-SBA-16 catalyst leading to 99% conversion and 71% butadiene selectivity while operating under mild conditions (325ºC, 1 atm, 0.23 hr-1). Several classes of silica (i.e., silica gels, fumed silicas, meoporous silicas) were evaluated as support, and SBA-16 was found to be the most promising. The nature of the SiO2 support wasmore » found to have a strong influence on both conversion and selectivity. Higher SiO2 catalyst surface areas lead to greater conversion due to increased Ag dispersion thus accelerating the initial ethanol dehydrogenation reaction. By independently varying Ag and ZrO2 loading, Ag was found to be the main component affecting ethanol conversion. Butadiene selectivity varied depending on the concentration of ZrO2 and acidic characteristics of the SiO2 support. A direct relationship between butadiene selectivity and concentration of Lewis acid sites was evidenced. Also, adding H2 to the feed had little effect on conversion while improving catalytic stability, however, selectivity to butadiene was decreased. Finally, catalyst regenerability was successfully demonstrated for several cycles.« less

Effect of the SiO 2 support on the catalytic performance of Ag/ZrO 2 /SiO 2 catalysts for the single-bed production of butadiene from ethanol

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dagle, Vanessa Lebarbier; Flake, Matthew D.; Lemmon, Teresa L.

A ternary Ag/ZrO2/SiO2 catalyst system was studied for the single-step conversion of ethanol to butadiene by varying the catalyst composition (Ag, Ir, or Pt metal component, Ag/ZrO2 loading, and choice of SiO2 support) and operating conditions (space velocity and feed gas composition). Exceptional catalytic performance was achieved over a 1%Ag/4%ZrO2/SiO2-SBA-16 catalyst leading to 99% conversion and 71% butadiene selectivity while operating under mild conditions (325ºC, 1 atm, 0.23 hr-1). Several classes of silica (i.e., silica gels, fumed silicas, meoporous silicas) were evaluated as support, and SBA-16 was found to be the most promising. The nature of the SiO2 support wasmore » found to have a strong influence on both conversion and selectivity. Higher SiO2 catalyst surface areas lead to greater conversion due to increased Ag dispersion thus accelerating the initial ethanol dehydrogenation reaction. By independently varying Ag and ZrO2 loading, Ag was found to be the main component affecting ethanol conversion. Butadiene selectivity varied depending on the concentration of ZrO2 and acidic characteristics of the SiO2 support. A direct relationship between butadiene selectivity and concentration of Lewis acid sites was evidenced. Also, adding H2 to the feed had little effect on conversion while improving catalytic stability, however, selectivity to butadiene was decreased. Finally, catalyst regenerability was successfully demonstrated for several cycles.« less

Simulation of ultra-high energy photon propagation with PRESHOWER 2.0

NASA Astrophysics Data System (ADS)

Homola, P.; Engel, R.; Pysz, A.; Wilczyński, H.

2013-05-01

In this paper we describe a new release of the PRESHOWER program, a tool for Monte Carlo simulation of propagation of ultra-high energy photons in the magnetic field of the Earth. The PRESHOWER program is designed to calculate magnetic pair production and bremsstrahlung and should be used together with other programs to simulate extensive air showers induced by photons. The main new features of the PRESHOWER code include a much faster algorithm applied in the procedures of simulating the processes of gamma conversion and bremsstrahlung, update of the geomagnetic field model, and a minor correction. The new simulation procedure increases the flexibility of the code so that it can also be applied to other magnetic field configurations such as, for example, encountered in the vicinity of the sun or neutron stars. Program summaryProgram title: PRESHOWER 2.0 Catalog identifier: ADWG_v2_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADWG_v2_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 3968 No. of bytes in distributed program, including test data, etc.: 37198 Distribution format: tar.gz Programming language: C, FORTRAN 77. Computer: Intel-Pentium based PC. Operating system: Linux or Unix. RAM:< 100 kB Classification: 1.1. Does the new version supercede the previous version?: Yes Catalog identifier of previous version: ADWG_v1_0 Journal reference of previous version: Comput. Phys. Comm. 173 (2005) 71 Nature of problem: Simulation of a cascade of particles initiated by UHE photon in magnetic field. Solution method: The primary photon is tracked until its conversion into an e+ e- pair. If conversion occurs each individual particle in the resultant preshower is checked for either bremsstrahlung radiation (electrons) or secondary gamma conversion (photons). Reasons for new version: Slow and outdated algorithm in the old version (a significant speed up is possible); Extension of the program to allow simulations also for extraterrestrial magnetic field configurations (e.g. neutron stars) and very long path lengths. Summary of revisions: A veto algorithm was introduced in the gamma conversion and bremsstrahlung tracking procedures. The length of the tracking step is now variable along the track and depends on the probability of the process expected to occur. The new algorithm reduces significantly the number of tracking steps and speeds up the execution of the program. The geomagnetic field model has been updated to IGRF-11, allowing for interpolations up to the year 2015. Numerical Recipes procedures to calculate modified Bessel functions have been replaced with an open source CERN routine DBSKA. One minor bug has been fixed. Restrictions: Gamma conversion into particles other than an electron pair is not considered. Spatial structure of the cascade is neglected. Additional comments: The following routines are supplied in the package, IGRF [1, 2], DBSKA [3], ran2 [4] Running time: 100 preshower events with primary energy 1020 eV require a 2.66 GHz CPU time of about 200 sec.; at the energy of 1021 eV, 600 sec.

Bio-inspired cofacial Fe porphyrin dimers for efficient electrocatalytic CO2 to CO conversion: Overpotential tuning by substituents at the porphyrin rings

PubMed Central

Zahran, Zaki N.; Mohamed, Eman A.; Naruta, Yoshinori

2016-01-01

Efficient reduction of CO2 into useful carbon resources particularly CO is an essential reaction for developing alternate sources of fuels and for reducing the greenhouse effect of CO2. The binuclear Ni, Fe−containing carbon monoxide dehydrogenase (CODHs) efficiently catalyzes the reduction of CO2 to CO. The location of Ni and Fe at proper positions allows their cooperation for CO2 to CO conversion through a push−pull mechanism. Bio−inspired from CODHs, we used several cofacial porphyrin dimers with different substituents as suitable ligands for holding two Fe ions with suitable Fe−Fe separation distance to efficiently and selectively promote CO2 to CO conversion with high turnover frequencies, TOFs. The substituents on the porphyrin rings greatly affect the catalysis process. By introducing electron-withdrawing/-donating groups, e.g. electron-withdrawing perfluorophenyl, at all meso positions of the porphyrin rings, the catalysis overpotential, η was minimized by ≈0.3 V compared to that obtained by introducing electron-donating mesityl groups. The Fe porphyrin dimers among reported catalysts are the most efficient ones for CO2 to CO conversion. Control experiments indicate that the high performance of the current CO2 to CO conversion catalysts is due to the presence of binuclear Fe centers at suitable Fe−Fe separation distance. PMID:27087483

Bio-inspired cofacial Fe porphyrin dimers for efficient electrocatalytic CO2 to CO conversion: Overpotential tuning by substituents at the porphyrin rings.

PubMed

Zahran, Zaki N; Mohamed, Eman A; Naruta, Yoshinori

2016-04-18

Efficient reduction of CO2 into useful carbon resources particularly CO is an essential reaction for developing alternate sources of fuels and for reducing the greenhouse effect of CO2. The binuclear Ni, Fe-containing carbon monoxide dehydrogenase (CODHs) efficiently catalyzes the reduction of CO2 to CO. The location of Ni and Fe at proper positions allows their cooperation for CO2 to CO conversion through a push-pull mechanism. Bio-inspired from CODHs, we used several cofacial porphyrin dimers with different substituents as suitable ligands for holding two Fe ions with suitable Fe-Fe separation distance to efficiently and selectively promote CO2 to CO conversion with high turnover frequencies, TOFs. The substituents on the porphyrin rings greatly affect the catalysis process. By introducing electron-withdrawing/-donating groups, e.g. electron-withdrawing perfluorophenyl, at all meso positions of the porphyrin rings, the catalysis overpotential, η was minimized by ≈0.3 V compared to that obtained by introducing electron-donating mesityl groups. The Fe porphyrin dimers among reported catalysts are the most efficient ones for CO2 to CO conversion. Control experiments indicate that the high performance of the current CO2 to CO conversion catalysts is due to the presence of binuclear Fe centers at suitable Fe-Fe separation distance.

Bio-inspired cofacial Fe porphyrin dimers for efficient electrocatalytic CO2 to CO conversion: Overpotential tuning by substituents at the porphyrin rings

NASA Astrophysics Data System (ADS)

Zahran, Zaki N.; Mohamed, Eman A.; Naruta, Yoshinori

2016-04-01

Efficient reduction of CO2 into useful carbon resources particularly CO is an essential reaction for developing alternate sources of fuels and for reducing the greenhouse effect of CO2. The binuclear Ni, Fe-containing carbon monoxide dehydrogenase (CODHs) efficiently catalyzes the reduction of CO2 to CO. The location of Ni and Fe at proper positions allows their cooperation for CO2 to CO conversion through a push-pull mechanism. Bio-inspired from CODHs, we used several cofacial porphyrin dimers with different substituents as suitable ligands for holding two Fe ions with suitable Fe-Fe separation distance to efficiently and selectively promote CO2 to CO conversion with high turnover frequencies, TOFs. The substituents on the porphyrin rings greatly affect the catalysis process. By introducing electron-withdrawing/-donating groups, e.g. electron-withdrawing perfluorophenyl, at all meso positions of the porphyrin rings, the catalysis overpotential, η was minimized by ≈0.3 V compared to that obtained by introducing electron-donating mesityl groups. The Fe porphyrin dimers among reported catalysts are the most efficient ones for CO2 to CO conversion. Control experiments indicate that the high performance of the current CO2 to CO conversion catalysts is due to the presence of binuclear Fe centers at suitable Fe-Fe separation distance.

A comparison of small-field tissue phantom ratio data generation methods for an Elekta Agility 6 MV photon beam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Richmond, Neil, E-mail: neil.richmond@stees.nhs.uk; Brackenridge, Robert

2014-04-01

Tissue-phantom ratios (TPRs) are a common dosimetric quantity used to describe the change in dose with depth in tissue. These can be challenging and time consuming to measure. The conversion of percentage depth dose (PDD) data using standard formulae is widely employed as an alternative method in generating TPR. However, the applicability of these formulae for small fields has been questioned in the literature. Functional representation has also been proposed for small-field TPR production. This article compares measured TPR data for small 6 MV photon fields against that generated by conversion of PDD using standard formulae to assess the efficacymore » of the conversion data. By functionally fitting the measured TPR data for square fields greater than 4 cm in length, the TPR curves for smaller fields are generated and compared with measurements. TPRs and PDDs were measured in a water tank for a range of square field sizes. The PDDs were converted to TPRs using standard formulae. TPRs for fields of 4 × 4 cm{sup 2} and larger were used to create functional fits. The parameterization coefficients were used to construct extrapolated TPR curves for 1 × 1 cm{sup 2}, 2 × 2-cm{sup 2}, and 3 × 3-cm{sup 2} fields. The TPR data generated using standard formulae were in excellent agreement with direct TPR measurements. The TPR data for 1 × 1-cm{sup 2}, 2 × 2-cm{sup 2}, and 3 × 3-cm{sup 2} fields created by extrapolation of the larger field functional fits gave inaccurate initial results. The corresponding mean differences for the 3 fields were 4.0%, 2.0%, and 0.9%. Generation of TPR data using a standard PDD-conversion methodology has been shown to give good agreement with our directly measured data for small fields. However, extrapolation of TPR data using the functional fit to fields of 4 × 4 cm{sup 2} or larger resulted in generation of TPR curves that did not compare well with the measured data.« less

A Conversation Analysis Approach to Researching eTandems--The Challenges of Data Collection

ERIC Educational Resources Information Center

Renner, Julia

2016-01-01

This article deals with the challenges of data collection from a Conversation Analysis (CA) perspective to researching synchronous, audio-visual eTandems. Conversation analysis is a research tradition that developed out of ethnomethodology and is concerned with the question of how social interaction in naturally occurring situations is organized.…

From SHG to mid-infrared SPDC generation in strained silicon waveguides

NASA Astrophysics Data System (ADS)

Castellan, Claudio; Trenti, Alessandro; Mancinelli, Mattia; Marchesini, Alessandro; Ghulinyan, Mher; Pucker, Georg; Pavesi, Lorenzo

2017-08-01

The centrosymmetric crystalline structure of Silicon inhibits second order nonlinear optical processes in this material. We report here that, by breaking the silicon symmetry with a stressing silicon nitride over-layer, Second Harmonic Generation (SHG) is obtained in suitably designed waveguides where multi-modal phase-matching is achieved. The modeling of the generated signal provides an effective strain-induced second order nonlinear coefficient of χ(2) = (0.30 +/- 0.02) pm/V. Our work opens also interesting perspectives on the reverse process, the Spontaneous Parametric Down Conversion (SPDC), through which it is possible to generate mid-infrared entangled photon pairs.

Bulk single crystal ternary substrates for a thermophotovoltaic energy conversion system

DOEpatents

Charache, Greg W.; Baldasaro, Paul F.; Nichols, Greg J.

1998-01-01

A thermophotovoltaic energy conversion device and a method for making the device. The device includes a substrate formed from a bulk single crystal material having a bandgap (E.sub.g) of 0.4 eV

Bulk single crystal ternary substrates for a thermophotovoltaic energy conversion system

DOEpatents

Charache, G.W.; Baldasaro, P.F.; Nichols, G.J.

1998-06-23

A thermophotovoltaic energy conversion device and a method for making the device are disclosed. The device includes a substrate formed from a bulk single crystal material having a bandgap (E{sub g}) of 0.4 eV < E{sub g} < 0.7 eV and an emitter fabricated on the substrate formed from one of a p-type or an n-type material. Another thermophotovoltaic energy conversion device includes a host substrate formed from a bulk single crystal material and lattice-matched ternary or quaternary III-V semiconductor active layers. 12 figs.

Collision cross sections and transport coefficients of O-, O2 -, O3 - and O4 - negative ions in O2, N2 and dry air for non-thermal plasmas modelling

NASA Astrophysics Data System (ADS)

Hennad, Ali; Yousfi, Mohammed

2018-02-01

The ions interaction data such as interaction potential parameters, elastic and inelastic collision cross sections and the transport coefficients (reduced mobility and diffusion coefficients) have been determined and analyzed in the case of the main negative oxygen ions (O-, O2 -, O3 - and O4 -) present in low temperature plasma at atmospheric pressure when colliding O2, N2 and dry air. The ion transport has been determined from an optimized Monte Carlo simulation using calculated elastic and experimentally fitted inelastic collision cross sections. The elastic momentum transfer collision cross sections have been calculated from a semi-classical JWKB approximation based on a ( n-4) rigid core interaction potential model. The cross sections sets involving elastic and inelastic processes were then validated using measured reduced mobility data and also diffusion coefficient whenever available in the literature. From the sets of elastic and inelastic collision cross sections thus obtained for the first time for O3-/O2, O2 -/N2, O3 -/N2, and O4 -/N2 systems, the ion transport coefficients were calculated in pure gases and dry air over a wide range of the density reduced electric field E/N.

Multimodal manifold-regularized transfer learning for MCI conversion prediction.

PubMed

Cheng, Bo; Liu, Mingxia; Suk, Heung-Il; Shen, Dinggang; Zhang, Daoqiang

2015-12-01

As the early stage of Alzheimer's disease (AD), mild cognitive impairment (MCI) has high chance to convert to AD. Effective prediction of such conversion from MCI to AD is of great importance for early diagnosis of AD and also for evaluating AD risk pre-symptomatically. Unlike most previous methods that used only the samples from a target domain to train a classifier, in this paper, we propose a novel multimodal manifold-regularized transfer learning (M2TL) method that jointly utilizes samples from another domain (e.g., AD vs. normal controls (NC)) as well as unlabeled samples to boost the performance of the MCI conversion prediction. Specifically, the proposed M2TL method includes two key components. The first one is a kernel-based maximum mean discrepancy criterion, which helps eliminate the potential negative effect induced by the distributional difference between the auxiliary domain (i.e., AD and NC) and the target domain (i.e., MCI converters (MCI-C) and MCI non-converters (MCI-NC)). The second one is a semi-supervised multimodal manifold-regularized least squares classification method, where the target-domain samples, the auxiliary-domain samples, and the unlabeled samples can be jointly used for training our classifier. Furthermore, with the integration of a group sparsity constraint into our objective function, the proposed M2TL has a capability of selecting the informative samples to build a robust classifier. Experimental results on the Alzheimer's Disease Neuroimaging Initiative (ADNI) database validate the effectiveness of the proposed method by significantly improving the classification accuracy of 80.1 % for MCI conversion prediction, and also outperforming the state-of-the-art methods.

Wet calcining of trona (sodium sesquicarbonate) and bicarbonate in a mixed solvent

NASA Astrophysics Data System (ADS)

Gärtner, R. S.; Witkamp, G. J.

2002-04-01

Trona ore is used in large amounts for the production of soda ash. A key step in this process is the conversion of trona (sodium sesquicarbonate: Na 2CO 3·NaHCO 3·2H 2O) into soda (sodium carbonate anhydrate: Na 2CO 3). Currently, this conversion is done industrially by calcining of the raw ore in rotary calciners at ca. 120°C or higher (Natural Soda Ash—Occurrences, Processing, and Use, Van Nostrand Reinhold, New York, 1991, p. 267). Trona can however be converted at lower temperatures by using a "wet calcining" technique. In this technique, trona is contacted with an organic or mixed organic-aqueous solvent at a conversion temperature that depends on the water activity of the used solvent. In pure ethylene glycol this temperature can be as low as 55°C. The conversion by "wet calcining" occurs very similar to that in the regular dry calcining process via a solid phase conversion. The anhydrate crystals form directly from the solid trona. This produces pseudomorphs (J. Chem. Eng. Data 8(3) (1963) 301), i.e. agglomerates of fine anhydrate crystals (1-10 μm). At high temperatures, dense, finely pored agglomerates are formed, while the outer shape of the agglomerate retains the prism shape of the trona crystal. At low conversion temperatures, loosely packed or even unstable agglomerates are found.

E-Cigarette Social Media Messages: A Text Mining Analysis of Marketing and Consumer Conversations on Twitter

PubMed Central

2016-01-01

Background As the use of electronic cigarettes (e-cigarettes) rises, social media likely influences public awareness and perception of this emerging tobacco product. Objective This study examined the public conversation on Twitter to determine overarching themes and insights for trending topics from commercial and consumer users. Methods Text mining uncovered key patterns and important topics for e-cigarettes on Twitter. SAS Text Miner 12.1 software (SAS Institute Inc) was used for descriptive text mining to reveal the primary topics from tweets collected from March 24, 2015, to July 3, 2015, using a Python script in conjunction with Twitter’s streaming application programming interface. A total of 18 keywords related to e-cigarettes were used and resulted in a total of 872,544 tweets that were sorted into overarching themes through a text topic node for tweets (126,127) and retweets (114,451) that represented more than 1% of the conversation. Results While some of the final themes were marketing-focused, many topics represented diverse proponent and user conversations that included discussion of policies, personal experiences, and the differentiation of e-cigarettes from traditional tobacco, often by pointing to the lack of evidence for the harm or risks of e-cigarettes or taking the position that e-cigarettes should be promoted as smoking cessation devices. Conclusions These findings reveal that unique, large-scale public conversations are occurring on Twitter alongside e-cigarette advertising and promotion. Proponents and users are turning to social media to share knowledge, experience, and questions about e-cigarette use. Future research should focus on these unique conversations to understand how they influence attitudes towards and use of e-cigarettes. PMID:27956376

Potential effects of tree-to-shrub type conversion on streamflow in California's Sierra Nevada

NASA Astrophysics Data System (ADS)

Baguskas, S. A.; Bart, R.; Molinari, N.; Tague, C.; Moritz, M.

2014-12-01

There is widespread concern that changes in climate and fire regime may lead to vegetation change across California, which in turn may influence watershed hydrology. Although plant cover is known to affect numerous hydrological processes, sensitivities to vegetation type and spatial arrangement of species within watersheds are not well understood. The primary objective of our research was to generate mechanistically-based projections of how potential type conversion from forested to shrub dominated systems may affect streamflow. During the 2014 growing season, we measured ecophysiological responses (plant water status and leaf gas exchange rates) of two dominant tree and shrub species to changes in seasonal water availability at two sites within the southern Sierra Nevada Critical Zone Observatory. Plant physiological observations were used to parameterize a process-based eco-hydrological model, RHESSys. This model was used to evaluate the impact of changes in seasonal water availability and vegetation type-conversion on streamflow. Based on our field observations, shrubs and trees had similar access to water through the early part of the growing season (April-early June); however, by late July, available water to shrubs was twice that of trees (shrubs, -0.55 ± 0.08 MPa; trees, -1.07 ± 0.08 MPa, p<0.05). Likewise, maximum transpiration (E) and carbon assimilation (A) rates per unit leaf area were twice as high for shrubs then trees in July (shrubs, A= 21 ± 2.3 μmol m-2 s-1, E=6.6 ± 1.8 mmol m-2 s-1; trees, A=8.2 ± 1.9 μmol m-2 s-1, E=2.4 ± 0.3 mmol m-2 s-1). Preliminary modeled changes in streamflow following simulated vegetation conversion were found to affect both the timing and amount of discharge. Controls on pre vs. post-conversion streamflow included changes in interception, rooting depth, energy balance, and plant response to changes in seasonal water availability. Our research demonstrates how linking strategic field data collection and mechanistic ecohydrologic models can be used as a robust tool for assessing the potential impact of vegetation change on the water balance of an ecosystem. This is an increasingly valuable approach to inform management decisions focused on adapting strategies based on projected changes in climate.

Grain Growth in Cu2ZnSnS4 Thin Films Using Sn Vapor Transport for Photovoltaic Applications

NASA Astrophysics Data System (ADS)

Toyama, Toshihiko; Konishi, Takafumi; Seo, Yuichi; Tsuji, Ryotaro; Terai, Kengo; Nakashima, Yuto; Okamoto, Hiroaki; Tsutsumi, Yasuo

2013-07-01

Cu2ZnSnS4 thin films containing grains grown using Sn vapor transport (TVT) were investigated. Structural characterization revealed that the grain sizes were equal to or larger than the film thickness (1-4 µm) and significantly larger than those in the case of growth without TVT (60 nm). Furthermore, no phase separation was detected. Photothermal diffraction spectroscopy revealed that the optical absorption coefficient was very low in the subgap region, 7×101 cm-1, suggesting the suppression of defect formation. Finally, a TVT-processed thin film was used as an absorber in a solar cell, and a conversion efficiency of 6.9% was achieved.

Moving frames and prolongation algebras

NASA Technical Reports Server (NTRS)

Estabrook, F. B.

1982-01-01

Differential ideals generated by sets of 2-forms which can be written with constant coefficients in a canonical basis of 1-forms are considered. By setting up a Cartan-Ehresmann connection, in a fiber bundle over a base space in which the 2-forms live, one finds an incomplete Lie algebra of vector fields in the fields in the fibers. Conversely, given this algebra (a prolongation algebra), one can derive the differential ideal. The two constructs are thus dual, and analysis of either derives properties of both. Such systems arise in the classical differential geometry of moving frames. Examples of this are discussed, together with examples arising more recently: the Korteweg-de Vries and Harrison-Ernst systems.

Long life hydrocarbon conversion catalyst and method of making

DOEpatents

Tonkovich, Anna Lee Y [Pasco, WA; Wang, Yong [Richland, WA; Gao, Yufei [Kennewick, WA

2002-11-12

The present invention includes a catalyst that has at least four layers, (1) porous support, (2) buffer layer, (3) interfacial layer, and optionally (4) catalyst layer. The buffer layer provides a transition of thermal expansion coefficient from the porous support to the interfacial layer thereby reducing thermal expansion stress as the catalyst is heated to high operating temperatures. The method of the present invention for making the at least three layer catalyst has the steps of (1) selecting a porous support, (2) solution depositing an interfacial layer thereon, and optionally (3) depositing a catalyst material onto the interfacial layer; wherein the improvement comprises (4) depositing a buffer layer between the porous support and the interfacial layer.

Oxygen self-diffusion in ThO 2 under pressure: Connecting point defect parameters with bulk properties

DOE PAGES

Cooper, Michael William D.; Fitzpatrick, M. E.; Tsoukalas, L. H.; ...

2016-06-06

ThO 2 is a candidate material for use in nuclear fuel applications and as such it is important to investigate its materials properties over a range of temperatures and pressures. In the present study molecular dynamics calculations are used to calculate elastic and expansivity data. These are used in the framework of a thermodynamic model, the cBΩ model, to calculate the oxygen self-diffusion coefficient in ThO 2 over a range of pressures (–10–10 GPa) and temperatures (300–1900 K). As a result, increasing the hydrostatic pressure leads to a significant reduction in oxygen self-diffusion. Conversely, negative hydrostatic pressure significantly enhances oxygenmore » self-diffusion.« less

ORGAN-SPECIFIC EXTERNAL DOSE COEFFICIENTS AND PROTECTIVE APRON TRANSMISSION FACTORS FOR HISTORICAL DOSE RECONSTRUCTION FOR MEDICAL PERSONNEL

PubMed Central

Simon, Steven L.

2014-01-01

While radiation absorbed dose (Gy) to the skin or other organs is sometimes estimated for patients from diagnostic radiologic examinations or therapeutic procedures, rarely is occupationally-received radiation absorbed dose to individual organs/tissues estimated for medical personnel, e.g., radiologic technologists or radiologists. Generally, for medical personnel, equivalent or effective radiation doses are estimated for compliance purposes. In the very few cases when organ doses to medical personnel are reconstructed, the data is usually for the purpose of epidemiologic studies, e.g., a study of historical doses and risks to a cohort of about 110,000 radiologic technologists presently underway at the U.S. National Cancer Institute. While ICRP and ICRU have published organ-specific external dose conversion coefficients (DCCs), i.e., absorbed dose to organs and tissues per unit air kerma and dose equivalent per unit air kerma, those factors have been primarily published for mono-energetic photons at selected energies. This presents two related problems for historical dose reconstruction, both of which are addressed here. It is necessary to derive conversion factors values for (i) continuous distributions of energy typical of diagnostic medical x rays (bremsstrahlung radiation), and (ii) for energies of particular radioisotopes used in medical procedures, neither of which are presented in published tables. For derivation of DCCs for bremsstrahlung radiation, combinations of x-ray tube potentials and filtrations were derived for different time periods based on a review of relevant literature. Three peak tube potentials (70 kV, 80 kV, and 90 kV) with four different amounts of beam filtration were determined to be applicable for historic dose reconstruction. The probability of these machine settings were assigned to each of the four time periods (earlier than 1949, 1949-1954, 1955-1968, and after 1968). Continuous functions were fit to each set of discrete values of the ICRP/ICRU mono-energetic DCCs and the functions integrated over the air-kerma weighted photon fluence of the 12 defined x-ray spectra. The air kerma-weighted DCCs in this work were developed specifically for an irradiation geometry of anterior to posterior (AP) and for the following tissues: thyroid, breast, ovary, lens of eye, lung, colon, testes, heart, skin (anterior side only), red bone marrow (RBM), heart, and brain. In addition, a series of functional relationships to predict DT per Ka values for RBM dependent on body mass index [BMI (kg m−2) ≡ weight per height2] and average photon energy were derived from a published analysis. Factors to account for attenuation of radiation by protective lead aprons were also developed. Because lead protective aprons often worn by radiology personnel not only reduce the intensity of x-ray exposure but also appreciably harden the transmitted fluence of bremsstrahlung x rays, DCCs were separately calculated for organs possibly protected by lead aprons by considering three cases: no apron, 0.25 mm Pb apron, and 0.5 mm Pb apron. For estimation of organ doses from conducting procedures with radioisotopes, continuous functions of the reported mono-energetic values were developed and DCCs were derived by estimation of the function at relevant energies. By considering the temporal changes in primary exposure-related parameters, e.g., energy distribution, the derived DCCs and transmission factors presented here allow for more realistic historical dose reconstructions for medical personnel when monitoring badge readings are the primary data on which estimation of an individual's organ doses are based. PMID:21617389

Organ-specific external dose coefficients and protective apron transmission factors for historical dose reconstruction for medical personnel.

PubMed

Simon, Steven L

2011-07-01

While radiation absorbed dose (Gy) to the skin or other organs is sometimes estimated for patients from diagnostic radiologic examinations or therapeutic procedures, rarely is occupationally-received radiation absorbed dose to individual organs/tissues estimated for medical personnel; e.g., radiologic technologists or radiologists. Generally, for medical personnel, equivalent or effective radiation doses are estimated for compliance purposes. In the very few cases when organ doses to medical personnel are reconstructed, the data is usually for the purpose of epidemiologic studies; e.g., a study of historical doses and risks to a cohort of about 110,000 radiologic technologists presently underway at the U.S. National Cancer Institute. While ICRP and ICRU have published organ-specific external dose conversion coefficients (DCCs) (i.e., absorbed dose to organs and tissues per unit air kerma and dose equivalent per unit air kerma), those factors have been published primarily for mono-energetic photons at selected energies. This presents two related problems for historical dose reconstruction, both of which are addressed here. It is necessary to derive conversion factor values for (1) continuous distributions of energy typical of diagnostic medical x-rays (bremsstrahlung radiation), and (2) energies of particular radioisotopes used in medical procedures, neither of which are presented in published tables. For derivation of DCCs for bremsstrahlung radiation, combinations of x-ray tube potentials and filtrations were derived for different time periods based on a review of relevant literature. Three peak tube potentials (70 kV, 80 kV, and 90 kV) with four different amounts of beam filtration were determined to be applicable for historic dose reconstruction. The probabilities of these machine settings were assigned to each of the four time periods (earlier than 1949, 1949-1954, 1955-1968, and after 1968). Continuous functions were fit to each set of discrete values of the ICRP/ICRU mono-energetic DCCs and the functions integrated over the air-kerma weighted photon fluence of the 12 defined x-ray spectra. The air kerma-weighted DCCs in this work were developed specifically for an irradiation geometry of anterior to posterior (AP) and for the following tissues: thyroid, breast, ovary, lens of eye, lung, colon, testes, heart, skin (anterior side only), red bone marrow (RBM), and brain. In addition, a series of functional relationships to predict DT Ka-1 values for RBM dependent on body mass index [BMI (kg m-2) ≡ weight per height] and average photon energy were derived from a published analysis. Factors to account for attenuation of radiation by protective lead aprons were also developed. Because lead protective aprons often worn by radiology personnel not only reduce the intensity of x-ray exposure but also appreciably harden the transmitted fluence of bremsstrahlung x-rays, DCCs were separately calculated for organs possibly protected by lead aprons by considering three cases: no apron, 0.25 mm Pb apron, and 0.5 mm Pb apron. For estimation of organ doses from conducting procedures with radioisotopes, continuous functions of the reported mono-energetic values were developed, and DCCs were derived by estimation of the function at relevant energies. By considering the temporal changes in primary exposure-related parameters (e.g., energy distribution), the derived DCCs and transmission factors presented here allow for more realistic historical dose reconstructions for medical personnel when monitoring badge readings are the primary data on which estimation of an individual's organ doses are based.

Photoisomerization of alfa calcidol by a sensitized quantum chain reaction.

PubMed

Estruch, Gastón A; Aramendía, Pedro F

2012-01-01

The production of vitamin D3 is a pharmaceutically relevant process, producing high added-value products. Precursors are extracts from vegetal origin but bearing mainly an E geometry in the 5,6 double bond. The synthesis of vitamin D3 (5-E-α-calcidol) with the correct Z stereochemistry in the 5,6 double bond from the E isomer using anthracene and triethylamine (TEA) as the sensitizer system was studied from the kinetic and mechanistic point of view. The sensitized isomerization of E-calcidol by irradiation of anthracene takes place only in deoxygenated solution and yields the Z isomer in ca 5% yield in the photostationary state. When TEA is added to the system, the E-Z reaction is not inhibited by oxygen any more, the quantum yield of photoisomerization to the Z isomer grows linearly with the concentration of E-calcidol, while conversions higher than 95% to the Z isomer are reached in the photostationary state and E-Z quantum yields as high as 45 at [E-calcidol] = 25 mM are reached. If TEA is replaced by 1,4-diazabicyclo[2.2.2]octane, the reaction rate drops to one-third at the same amine concentration. The observations can be explained by a quantum chain reaction mechanism. The high conversion achieved eliminates the need of isomer separation. © 2011 Wiley Periodicals, Inc. Photochemistry and Photobiology © 2011 The American Society of Photobiology.

Effect of sodium ascorbate on degree of conversion and bond strength of RealSeal SE to sodium hypochlorite treated root dentin.

PubMed

Shrestha, Deepti; Wu, Wan-Cui; He, Qing-Yin; Wei, Xi; Ling, Jun-Qi

2013-01-01

The aim of this study was to investigate the effect of sodium ascorbate (Sa) on degree of conversion (DC) and bond strength (BS) of RealSeal SE to sodium hypochlorite (NaOCl) treated root dentin. Two hundreds simulated canals were prepared and irrigated with Distilled water(DW), 1.3% NaOCl (1.3% N), 5.2% NaOCl (5.2% N), MTAD, 17% EDTA (EDTA), 10% Sa, 1.3% NaOCl/MTAD (N-M), 1.3% NaOCl/Sa/MTAD(N-Sa-M), 5.2% NaOCl/EDTA(N-E), and 5.2% NaOCl/Sa/EDTA (N-Sa-E) respectively. They were subsequently bulk filled with RealSeal SE and analyzed with micro-Raman spectroscopy and universal testing machine for DC and BS respectively. One-way ANOVA and post hoc Tukey's test showed DC of 1.3% N, 5.2% N, N-M and N-E were significantly lower (p<0.01) than other six groups. BS of DW, Sa, N-M were significantly lower than 1.3% N, 5.2% N, MTAD, EDTA, N-Sa-M and N-E (p<0.01), and group N-Sa-E achieved the highest BS among all groups (p<0.01). NaOCl negatively affected DC and BS of RealSeal SE, which could be reversed with 10% Sa.

[Contributions by Conversation Analysis to healthcare studies: reflections based on patients' attributions].

PubMed

Ostermann, Ana Cristina; de Souza, Joseane

2009-07-01

This study is part of a larger research project aimed at investigating physician-patient interactions in women's health. In this article, by looking at naturalistic data, which consists of 144 fully transcribed audio recordings of face-to-face interactions between gynecologists/obstetricians and female patients, we propose to: (1) present the theoretical and methodological approach of Conversation Analysis to health studies in Brazil; (2) discuss how Conversation Analysis can reveal how 'macro' questions (e.g. National Policy for the Humanization of Healthcare) are (or are not) translated into interactional practices at the 'micro' level and, thus, emphasize the issues of language and communication, only briefly discussed in the HumanizaSUS documents; and (3) analyze how a specific interactional phenomenon, 'attribution' (i.e. voluntary explanations about the possible causes of their problems), might describe ordinary and concrete humanization practices in healthcare services.