Search

Effect of weight fraction (WF, mg/dL) of nanographite (NG, 400 nm) on electrical, mechanical and wear and characteristics of graphite epoxy composites (GECs) were investigated. For this purpose, a series of GECs was prepared through dispersion of various WF of NG into epoxy resin, followed by curing with polyamine. Dispersion of NG into epoxy matrix and onward formation of GECs and was revealed through Ultraviolet, Fourier transformed Infrared spectra and atomic force micrographs. Photoelastic analysis in combination with atomic force microscopy reveals the presence of uniformly dispersed domain of NG into stress free matrix of GECs with fringe order ranging 0.23 to 0.61 under compression of 8 to 20 kgf. GECs have rendered a rising trend in DC conductance ranging 98.32 nS/cm to 0.54 µS/cm with electrical percolation threshold at 175 WF of NG. GECs have shown enhanced compressive, impact, tensile, strength, Rockwell hardness and wear resistance at 200WF of NG. In general, GECs has shown a marginal modification in their compressive strength by 5.30% over cured epoxy (CE). However, impact (%) and tensile strengths (%) of GECs were largely improved to 31.78 and 43.98 over CE. [ABSTRACT FROM AUTHOR]

The CASSANDRA, average atom, opacity code uses the local density approximation (LDA) to calculate electron exchange interactions and this introduces inaccuracies due to the inconsistent treatment of the Coulomb and exchange energy terms of the average total energy equation. To correct this inconsistency, the Optimized Atomic Central Potential Method (OPM) of calculating exchange interactions has been incorporated into CASSANDRA. The LDA and OPM formalisms are discussed and the reason for the discrepancy when using the LDA is highlighted. CASSANDRA uses a Taylor series expansion about an average atom when computing transition energies and uses Janak's Theorem to determine the Taylor series coefficients. Janak's Theorem does not apply to the OPM; however, a corollary to Janak's Theorem has been employed in the OPM implementation. A derivation of this corollary is provided. Results of simulations from CASSANDRA using the OPM are shown and compared against CASSANDRA LDA, DAVROS (a detailed term accounting opacity code), the GRASP2K atomic physics code and experimental data. [ABSTRACT FROM AUTHOR]

Generalized analytical expressions for the two-electron relativistic Unresolved-Transition-Array (UTA) energy variance and shift for electric and magnetic transitions of general multipole order are presented. The revised expressions are shown to agree with the exact moments calculated directly from the energy levels of two-electron configurations. We show that for electric transitions of even multipole order and for magnetic transitions, the available expressions in the literature, which are implemented in widely used atomic codes, are incorrect. We suggest an alternative method for the calculation of the UTA energy variance and shift by using the analytical expressions for the two-electron energy levels and line-strengths. The method is much more efficient and simple than the use of the traditional lengthy analytic expressions. Finally, the effect of UTA widths on Super-Transition-Array (STA) spectral opacity is shown for several examples. [ABSTRACT FROM AUTHOR]

Abstract: We present the main results of the 7th Non-Local Thermodynamic Equilibrium Code Comparison Workshop held in December 2011 in Vienna, Austria. More than twenty researchers from nine countries, who actively work on development of collisional-radiative codes for plasma kinetics modeling, attended the meeting and submitted their results for a number of comparison cases. The cases included free-electron-laser-inspired time-dependent relaxation of photoexcited Ne-like Ar, ionization balance and spectra for highly charged tungsten, spectroscopic diagnostics of krypton L-shell spectra, and an investigation of Ne model convergence with principal quantum number. [Copyright &y& Elsevier]

[Display omitted] • Thimerosal damages the structure of hemoglobin inducing the loss of its main function as O 2 transporter. • Raman indicates that thimerosal causes a distortion in the hemoglobin heme ring. • Ethylmercury decreases the amount of thiol groups free from hemoglobin. • Atomic Force Microscopy shows morphological changes caused by thimerosal. • Thimerosal crosses the erythrocyte membrane without causing osmotic fragility. Thimerosal (TM) is an organic mercury compound used as a preservative in many pharmacological inputs. Mercury toxicity is related to structural and functional changes in macromolecules such as hemoglobin (Hb) in erythrocytes (Ery). Human Hb and Ery were used to evaluate O 2 uptake based on the TM concentration, incubation time, and temperature. The influence of TM on the sulfhydryl content, production of reactive oxygen species (ROS), and membrane fragility was also evaluated. Raman spectra and atomic force microscopy (AFM) profiles for Ery in the presence and absence of TM were calculated, and docking studies were performed. At 37 °C, with 2.50 μM TM (higher concentration) and after 5 min of incubation in Hb and Ery, we observed a reduction in O 2 uptake of up to 50 %, while HgCl 2 , which was used as a positive control, showed a reduction of at least 62 %. Total thiol assays in the presence of NEM (thiol blocker) quantified the preservation of almost 60 % of free SH in Ery. Based on the Raman spectrum profile from Ery-TM, structural differences in the porphyrinic ring and the membrane lipid content were confirmed. Finally, studies using AFM showed changes in the morphology and biomechanical properties of Ery. Theoretical studies confirmed these experimental results and showed that the cysteine (Cys) residues present in Hb are involved in the binding of TM. Our results show that TM binds to human Hb via free Cys residues, causing conformation changes and leading to harmful effects associated with O 2 transport. [ABSTRACT FROM AUTHOR]

Abstract: The unresolved transition array (UTA) model of atomic spectra describes the lines in a configuration-to-configuration transition array with a single feature that conserves the total strength as well as the energy first and second strength-weighted moments. A new model is proposed that uses a relatively small detailed line-by-line calculation together with the extant variance formula to generate a series of Gaussians to describe the transition array. This partially resolved transition array (PRTA) model conserves the known array properties, yields improved higher moments, and systematically accounts for initial level populations. Numerical examples show that the PRTA model provides excellent fidelity to line-by-line methods using only a small fraction of the computational effort for the full calculations. [Copyright &y& Elsevier]

Abstract: The structures and energies of small CaSi n (n =2–10) species and their anions have been systematically investigated by means of the Gaussian-3 (G3) theory. The electron affinities have been presented and compared with those of MgSi n and BeSi n . The ground state structures for all of these species are found to be “substitutional structure”, which are derived from Si n +1 by replacing a Si atom with a Ca atom. The reliable adiabatic electron affinities of CaSi n have been predicted to be 1.56eV for CaSi2, 1.77eV for CaSi3, 2.01eV for CaSi4, 2.06eV for CaSi5, 1.97eV for CaSi6, 1.98eV for CaSi7, 1.86eV for CaSi8, 2.49eV for CaSi9, and 2.32eV for CaSi10. The dissociation energies of Ca atom from the lowest energy structure of CaSi n clusters have been calculated in order to examine relative stabilities. Compared with those of BeSi n and MgSi n , the dissociation energies of Mg from MgSi n are the smallest. The charge transfer of CaSi n and BeSi n has also been computed to further understand the interaction between the metal atom and the silicon clusters. [ABSTRACT FROM AUTHOR]

Abstract: The impact of the third (skewness) and fourth (kurtosis) reduced centered moments on the statistical modeling of E1 lines in complex atomic spectra is investigated through the use of Gram–Charlier, Normal Inverse Gaussian and Generalized Gaussian distributions. It is shown that the modeling of unresolved transition arrays with non-Gaussian distributions may reveal more detailed structures, due essentially to the large value of the kurtosis. In the present work, focus is put essentially on the Generalized Gaussian, the power of the argument in the exponential being constrained by the kurtosis value. The relevance of the new statistical line distribution is checked by comparisons with smoothed detailed line-by-line calculations and through the analysis of 2p →3d transitions of recent laser or Z-pinch absorption measurements. The issue of calculating high-order moments is also discussed (Racah algebra, Jucys graphical method, semi-empirical approach…). [Copyright &y& Elsevier]

In this technical note we report on a slight but important modification in a recently developed backscattered neutron-based void fraction evaluation scheme for slab materials, and we describe an add-on numerical scheme for computing total (direct plus diffuse) neutron transmission through a test slab. In the void fraction evaluation scheme, the broad neutron beam consists of a monodirectional (singular), normally incident component and a smooth (regular), angularly continuous component, i.e., a mixed neutron beam. Once the void fraction of the test slab has been evaluated, the diffuse component of the angular flux of transmitted neutrons can be computed from an accurate spherical harmonics-discrete ordinates solution of the neutron beam transport problem defined in a reduced slab domain (the direct component is rather straightforward to compute). The add-on scheme described here can be used to evaluate the amount of neutrons that escape from the slab through the back side. Numerical results are given to illustrate the usefulness of our add-on scheme in neutron shielding studies. [ABSTRACT FROM AUTHOR]

Abstract: We present the development of population kinetics models for tin plasmas that can be employed to design an EUV source for microlithography. The atomic kinetic code is constrained for the requirement that the model must be able to calculate spectral emissivity and opacity that can be used in radiation hydrodynamic simulations. Methods to develop compact and reliable atomic model with an appropriate set of atomic states are discussed. Specifically, after investigation of model dependencies and comparison experiment, we improve the effect of configuration interaction and the treatment of satellite lines. Using the present atomic model we discuss the temperature and density dependencies of the emissivity, as well as conditions necessary to obtain high efficiency EUV power at λ =13.5nm. [Copyright &y& Elsevier]

Copyright of Polimery is the property of Industrial Chemistry Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Dicle University Journal of Ziya Gokalp Education Faculty / Dicle Üniversitesi Ziya Gökalp Eğitim Fakültesi Dergisi is the property of Dicle University Journal of Ziya Gokalp Education Faculty and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: Radiative opacity is a key parameter to understanding the transport of energy in high energy density plasmas. Many calculations of opacity apply approximations that do not fully resolve the true line structure of the frequency dependent absorption spectrum and the accuracy of such results is uncertain for simulations containing many complex ions. The DAVROS opacity code has been developed to perform Detailed Term Accounting (DTA) calculations with the aim of resolving the fine structure resulting from the myriad line transitions due to arbitrarily complex atomic configurations. By making use of High Performance Computing (HPC), such calculations, whilst not yet routine, are now more feasible. Some illustrative results from DAVROS are presented and comparisons made with experiment data. [Copyright &y& Elsevier]