Proceedings of the STRESS Data Review Meeting, 29-30 November 1977

DTIC Science & Technology

1978-06-01

INSULATORS MAGNETOMETER BEACON ANTENNA fe?^ S-BAND ANTENNA- -DC PROBE SENSING ELEMENT PLASMA FREQUENCY PROBE MONOPOLE -GUARD ELECTRODE PLASMA...have demonstrated, using calculational results from MICE and MRHYDE (MHD computer codes), that the gradient-drift instability is the one primarily

VizieR Online Data Catalog: FAMA code for stellar parameters and abundances (Magrini+, 2013)

NASA Astrophysics Data System (ADS)

Magrini, L.; Randich, S.; Friel, E.; Spina, L.; Jacobson, H.; Cantat-Gaudin, T.; Donati, P.; Baglioni, R.; Maiorca, E.; Bragaglia, A.; Sordo, R.; Vallenari, A.

2013-07-01

FAMA v.1, July 2013, distributed with MOOGv2013 and Kurucz models. Perl Codes: read_out2.pl read_final.pl driver.pl sclipping_26.0.pl sclipping_final.pl sclipping_26.1.pl confronta.pl fama.pl Model atmopheres and interpolator (Kurucz models): MODEL_ATMO MOOG_files: files to compile MOOG (the most recent version of MOOG can be obtained from http://www.as.utexas.edu/~chris/moog.html) FAMAmoogfiles: files to update when compiling MOOG OUTPUT: directory in which the results will be stored, contains a sm macro to produce final plots automoog.par: files with parameters for FAMA 1) OUTPUTdir 2) MOOGdir 3) modelsdir 4) 1.0 (default) percentage of the dispersion of FeI abundances to be considered to compute the errors on the stellar parameters, 1.0 means 100%, thus to compute e.g., the error on Teff we allow to code to find the Teff corresponding to a slope given by σ(FeI)/range(EP). 5) 1.2 (default) σ clipping for FeI lines 6) 1.0 (default) σ clipping for FeII lines 7) 1.0 (default) σ clipping for the other elements 8) 1.0 (default) value of the QP parameter, higher values mean less strong convergence criteria. star.iron: EWs in the correct format to test the code sun.par: initial parameters for the test (1 data file).

Simple Common Plane contact algorithm for explicit FE/FD methods

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

Vorobiev, O

2006-12-18

Common-plane (CP) algorithm is widely used in Discrete Element Method (DEM) to model contact forces between interacting particles or blocks. A new simple contact algorithm is proposed to model contacts in FE/FD methods which is similar to the CP algorithm. The CP is defined as a plane separating interacting faces of FE/FD mesh instead of blocks or particles used in the original CP method. The new method does not require iterations even for very stiff contacts. It is very robust and easy to implement both in 2D and 3D parallel codes.

Finite element code development for modeling detonation of HMX composites

NASA Astrophysics Data System (ADS)

Duran, Adam V.; Sundararaghavan, Veera

2017-01-01

In this work, we present a hydrodynamics code for modeling shock and detonation waves in HMX. A stable efficient solution strategy based on a Taylor-Galerkin finite element (FE) discretization was developed to solve the reactive Euler equations. In our code, well calibrated equations of state for the solid unreacted material and gaseous reaction products have been implemented, along with a chemical reaction scheme and a mixing rule to define the properties of partially reacted states. A linear Gruneisen equation of state was employed for the unreacted HMX calibrated from experiments. The JWL form was used to model the EOS of gaseous reaction products. It is assumed that the unreacted explosive and reaction products are in both pressure and temperature equilibrium. The overall specific volume and internal energy was computed using the rule of mixtures. Arrhenius kinetics scheme was integrated to model the chemical reactions. A locally controlled dissipation was introduced that induces a non-oscillatory stabilized scheme for the shock front. The FE model was validated using analytical solutions for SOD shock and ZND strong detonation models. Benchmark problems are presented for geometries in which a single HMX crystal is subjected to a shock condition.

Spallogenic Light Elements and Cosmic Ray Origin

NASA Technical Reports Server (NTRS)

Ramaty, Reuven

2000-01-01

Most of the Galactic Li-6, all of the Be and the bulk of the B are cosmic ray produced. I will discuss the production mechanisms and detail a recently developed evolutionary code for Fe,O and these light elements. I will review the leading models for Li, Be and B origin and discuss their implications on cosmic ray origin. I will also show evidence for extragalactic production of Li-6.

High-precision abundances of Sc, Mn, Cu, and Ba in solar twins. Trends of element ratios with stellar age

NASA Astrophysics Data System (ADS)

Nissen, P. E.

2016-09-01

Aims: A previous study of correlations between element abundances and ages of solar twin stars in the solar neighborhood is extended to include Sc, Mn, Cu, and Ba to obtain new information on the nucleosynthetic history of these elements. Methods: HARPS spectra with S/N ≳ 600 are used to derive very precise (σ ~ 0.01 dex) differential abundances of Sc, Mn, Cu, and Ba for 21 solar twins and the Sun. The analysis is based on MARCS model atmospheres with parameters determined from the excitation and ionization balance of Fe lines. Stellar ages with internal errors less than 1 Gyr are obtained by interpolation in the log g - Teff diagram between isochrones based on the Aarhus Stellar Evolution Code. Results: For stars younger than 6 Gyr, [Sc/Fe], [Mn/Fe], [Cu/Fe], and [Ba/Fe] are tightly correlated with stellar age, which is also the case for the other elements previously studied; linear relations between [X/Fe] and age have χ^2red ˜ 1, and for most stars the residuals do not depend on elemental condensation temperature. For ages between 6 and 9 Gyr, the [X/Fe] - age correlations break down and the stars split up into two groups having respectively high and low [X/Fe] for the odd-Z elements Na, Al, Sc, and Cu. Conclusions: While stars in the solar neighborhood younger than ~ 6 Gyr were formed from interstellar gas with a smooth chemical evolution, older stars seem to have originated from regions enriched by supernovae with different neutron excesses. Correlations between abundance ratios and stellar age suggest that: (I) Sc is made in Type II supernovae along with the α-capture elements; (II) the Type II to Ia yield ratio is about the same for Mn and Fe; (III) Cu is mainly made by the weak s-process in massive stars; (iv) the Ba/Y yield ratio for asymptotic giant branch stars increases with decreasing stellar mass; (v) [Y/Mg] and [Y/Al] can be used as chemical clocks when determining ages of solar metallicity stars. Based on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory under programs 072.C-0488, 088.C-0323, 183.C-0972, 188.C-0265.

Three-Dimensional Plasma-Based Stall Control Simulations with Coupled First-Principles Approaches

DTIC Science & Technology

2006-07-01

flow code, developed at the Computational Plasma Dynamics Laboratory at Kettering University. The method is based on a versatile finite-element ( FE ...McLaughlin, T., and Baughn, J., 2005. “Acoustic testing of the dielectric barrier dis- charge ( dbd ) plasma actuator”. AIAA Paper 2005-0565, Jan

Finite Element Analysis of Drilling of Carbon Fibre Reinforced Composites

NASA Astrophysics Data System (ADS)

Isbilir, Ozden; Ghassemieh, Elaheh

2012-06-01

Despite the increased applications of the composite materials in aerospace due to their exceptional physical and mechanical properties, the machining of composites remains a challenge. Fibre reinforced laminated composites are prone to different damages during machining process such as delamination, fibre pull-out, microcracks, thermal damages. Optimization of the drilling process parameters can reduces the probability of these damages. In the current research, a 3D finite element (FE) model is developed of the process of drilling in the carbon fibre reinforced composite (CFC). The FE model is used to investigate the effects of cutting speed and feed rate on thrust force, torque and delamination in the drilling of carbon fiber reinforced laminated composite. A mesoscale FE model taking into account of the different oriented plies and interfaces has been proposed to predict different damage modes in the plies and delamination. For validation purposes, experimental drilling tests have been performed and compared to the results of the finite element analysis. Using Matlab a digital image analysis code has been developed to assess the delamination factor produced in CFC as a result of drilling.

Single-trabecula building block for large-scale finite element models of cancellous bone.

PubMed

Dagan, D; Be'ery, M; Gefen, A

2004-07-01

Recent development of high-resolution imaging of cancellous bone allows finite element (FE) analysis of bone tissue stresses and strains in individual trabeculae. However, specimen-specific stress/strain analyses can include effects of anatomical variations and local damage that can bias the interpretation of the results from individual specimens with respect to large populations. This study developed a standard (generic) 'building-block' of a trabecula for large-scale FE models. Being parametric and based on statistics of dimensions of ovine trabeculae, this building block can be scaled for trabecular thickness and length and be used in commercial or custom-made FE codes to construct generic, large-scale FE models of bone, using less computer power than that currently required to reproduce the accurate micro-architecture of trabecular bone. Orthogonal lattices constructed with this building block, after it was scaled to trabeculae of the human proximal femur, provided apparent elastic moduli of approximately 150 MPa, in good agreement with experimental data for the stiffness of cancellous bone from this site. Likewise, lattices with thinner, osteoporotic-like trabeculae could predict a reduction of approximately 30% in the apparent elastic modulus, as reported in experimental studies of osteoporotic femora. Based on these comparisons, it is concluded that the single-trabecula element developed in the present study is well-suited for representing cancellous bone in large-scale generic FE simulations.

Investigation of fatigue assessments accuracy for beam weldments considering material data input and FE-mode type

NASA Astrophysics Data System (ADS)

Gorash, Yevgen; Comlekci, Tugrul; MacKenzie, Donald

2017-05-01

This study investigates the effects of fatigue material data and finite element types on accuracy of residual life assessments under high cycle fatigue. The bending of cross-beam connections is simulated in ANSYS Workbench for different combinations of structural member shapes made of a typical structural steel. The stress analysis of weldments with specific dimensions and loading applied is implemented using solid and shell elements. The stress results are transferred to the fatigue code nCode DesignLife for the residual life prediction. Considering the effects of mean stress using FKM approach, bending and thickness according to BS 7608:2014, fatigue life is predicted using the Volvo method and stress integration rules from ASME Boiler & Pressure Vessel Code. Three different pairs of S-N curves are considered in this work including generic seam weld curves and curves for the equivalent Japanese steel JIS G3106-SM490B. The S-N curve parameters for the steel are identified using the experimental data available from NIMS fatigue data sheets employing least square method and considering thickness and mean stress corrections. The numerical predictions are compared to the available experimental results indicating the most preferable fatigue data input, range of applicability and FE-model formulation to achieve the best accuracy.

Inflow, Outflow, Yields, and Stellar Population Mixing in Chemical Evolution Models

NASA Astrophysics Data System (ADS)

Andrews, Brett H.; Weinberg, David H.; Schönrich, Ralph; Johnson, Jennifer A.

2017-02-01

Chemical evolution models are powerful tools for interpreting stellar abundance surveys and understanding galaxy evolution. However, their predictions depend heavily on the treatment of inflow, outflow, star formation efficiency (SFE), the stellar initial mass function, the SN Ia delay time distribution, stellar yields, and stellar population mixing. Using flexCE, a flexible one-zone chemical evolution code, we investigate the effects of and trade-offs between parameters. Two critical parameters are SFE and the outflow mass-loading parameter, which shift the knee in [O/Fe]-[Fe/H] and the equilibrium abundances that the simulations asymptotically approach, respectively. One-zone models with simple star formation histories follow narrow tracks in [O/Fe]-[Fe/H] unlike the observed bimodality (separate high-α and low-α sequences) in this plane. A mix of one-zone models with inflow timescale and outflow mass-loading parameter variations, motivated by the inside-out galaxy formation scenario with radial mixing, reproduces the two sequences better than a one-zone model with two infall epochs. We present [X/Fe]-[Fe/H] tracks for 20 elements assuming three different supernova yield models and find some significant discrepancies with solar neighborhood observations, especially for elements with strongly metallicity-dependent yields. We apply principal component abundance analysis to the simulations and existing data to reveal the main correlations among abundances and quantify their contributions to variation in abundance space. For the stellar population mixing scenario, the abundances of α-elements and elements with metallicity-dependent yields dominate the first and second principal components, respectively, and collectively explain 99% of the variance in the model. flexCE is a python package available at https://github.com/bretthandrews/flexCE.

Inflow, Outflow, Yields, and Stellar Population Mixing in Chemical Evolution Models

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

Andrews, Brett H.; Weinberg, David H.; Schönrich, Ralph

Chemical evolution models are powerful tools for interpreting stellar abundance surveys and understanding galaxy evolution. However, their predictions depend heavily on the treatment of inflow, outflow, star formation efficiency (SFE), the stellar initial mass function, the SN Ia delay time distribution, stellar yields, and stellar population mixing. Using flexCE, a flexible one-zone chemical evolution code, we investigate the effects of and trade-offs between parameters. Two critical parameters are SFE and the outflow mass-loading parameter, which shift the knee in [O/Fe]–[Fe/H] and the equilibrium abundances that the simulations asymptotically approach, respectively. One-zone models with simple star formation histories follow narrow tracksmore » in [O/Fe]–[Fe/H] unlike the observed bimodality (separate high- α and low- α sequences) in this plane. A mix of one-zone models with inflow timescale and outflow mass-loading parameter variations, motivated by the inside-out galaxy formation scenario with radial mixing, reproduces the two sequences better than a one-zone model with two infall epochs. We present [X/Fe]–[Fe/H] tracks for 20 elements assuming three different supernova yield models and find some significant discrepancies with solar neighborhood observations, especially for elements with strongly metallicity-dependent yields. We apply principal component abundance analysis to the simulations and existing data to reveal the main correlations among abundances and quantify their contributions to variation in abundance space. For the stellar population mixing scenario, the abundances of α -elements and elements with metallicity-dependent yields dominate the first and second principal components, respectively, and collectively explain 99% of the variance in the model. flexCE is a python package available at https://github.com/bretthandrews/flexCE.« less

Calibration of 3D ALE finite element model from experiments on friction stir welding of lap joints

NASA Astrophysics Data System (ADS)

Fourment, Lionel; Gastebois, Sabrina; Dubourg, Laurent

2016-10-01

In order to support the design of such a complex process like Friction Stir Welding (FSW) for the aeronautic industry, numerical simulation software requires (1) developing an efficient and accurate Finite Element (F.E.) formulation that allows predicting welding defects, (2) properly modeling the thermo-mechanical complexity of the FSW process and (3) calibrating the F.E. model from accurate measurements from FSW experiments. This work uses a parallel ALE formulation developed in the Forge® F.E. code to model the different possible defects (flashes and worm holes), while pin and shoulder threads are modeled by a new friction law at the tool / material interface. FSW experiments require using a complex tool with scroll on shoulder, which is instrumented for providing sensitive thermal data close to the joint. Calibration of unknown material thermal coefficients, constitutive equations parameters and friction model from measured forces, torques and temperatures is carried out using two F.E. models, Eulerian and ALE, to reach a satisfactory agreement assessed by the proper sensitivity of the simulation to process parameters.

Overcoming Challenges in Kinetic Modeling of Magnetized Plasmas and Vacuum Electronic Devices

NASA Astrophysics Data System (ADS)

Omelchenko, Yuri; Na, Dong-Yeop; Teixeira, Fernando

2017-10-01

We transform the state-of-the art of plasma modeling by taking advantage of novel computational techniques for fast and robust integration of multiscale hybrid (full particle ions, fluid electrons, no displacement current) and full-PIC models. These models are implemented in 3D HYPERS and axisymmetric full-PIC CONPIC codes. HYPERS is a massively parallel, asynchronous code. The HYPERS solver does not step fields and particles synchronously in time but instead executes local variable updates (events) at their self-adaptive rates while preserving fundamental conservation laws. The charge-conserving CONPIC code has a matrix-free explicit finite-element (FE) solver based on a sparse-approximate inverse (SPAI) algorithm. This explicit solver approximates the inverse FE system matrix (``mass'' matrix) using successive sparsity pattern orders of the original matrix. It does not reduce the set of Maxwell's equations to a vector-wave (curl-curl) equation of second order but instead utilizes the standard coupled first-order Maxwell's system. We discuss the ability of our codes to accurately and efficiently account for multiscale physical phenomena in 3D magnetized space and laboratory plasmas and axisymmetric vacuum electronic devices.

Multi-scale finite element analyses for stress and strain evaluations of braid fibril artificial blood vessel and smooth muscle cell.

PubMed

Nakamachi, Eiji; Uchida, Takahiro; Kuramae, Hiroyuki; Morita, Yusuke

2014-08-01

In this study, we developed a multi-scale finite element (FE) analysis code to obtain the stress and strain that occurred in the smooth muscle cell (SMC) at micro-scale, which was seeded in the real fabricated braid fibril artificial blood vessel. This FE code can predict the dynamic response of stress under the blood pressure loading. We try to establish a computer-aided engineering (CAE)-driven scaffold design technique for the blood vessel regeneration. Until now, there occurred the great progresses for the endothelial cell activation and intima layer regeneration in the blood vessel regeneration study. However, there remains the difficulty of the SMC activation and media layer regeneration. Therefore, many researchers are now studying to elucidate the fundamental mechanism of SMC activation and media layer regeneration by using the biomechanical technique. As the numerical tool, we used the dynamic-explicit FE code PAM-CRASH, ESI Ltd. For the material models, the nonlinear viscoelastic constitutive law was adapted for the human blood vessel, SMC and the extra-cellular matrix, and the elastic law for the polyglycolic acid (PGA) fiber. Through macro-FE and micro-FE analyses of fabricated braid fibril tubes by using PGA fiber under the combined conditions of the orientation angle and the pitch of fiber, we searched an appropriate structure for the stress stimulation for SMC functionalization. Objectives of this study are indicated as follows: 1. to analyze the stress and strain of the human blood vessel and SMC, and 2. to calculate stress and strain of the real fabricated braid fibril artificial blood vessel and SMC to search an appropriate PGA fiber structure under combined conditions of PGA fiber numbers, 12 and 24, and the helical orientation angles of fiber, 15, 30, 45, 60, and 75 degrees. Finally, we found a braid fibril tube, which has an angle of 15 degree and 12 PGA fibers, as a most appropriate artificial blood vessel for SMC functionalization. Copyright © 2014 John Wiley & Sons, Ltd.

Finite element code development for modeling detonation of HMX composites

NASA Astrophysics Data System (ADS)

Duran, Adam; Sundararaghavan, Veera

2015-06-01

In this talk, we present a hydrodynamics code for modeling shock and detonation waves in HMX. A stable efficient solution strategy based on a Taylor-Galerkin finite element (FE) discretization was developed to solve the reactive Euler equations. In our code, well calibrated equations of state for the solid unreacted material and gaseous reaction products have been implemented, along with a chemical reaction scheme and a mixing rule to define the properties of partially reacted states. A linear Gruneisen equation of state was employed for the unreacted HMX calibrated from experiments. The JWL form was used to model the EOS of gaseous reaction products. It is assumed that the unreacted explosive and reaction products are in both pressure and temperature equilibrium. The overall specific volume and internal energy was computed using the rule of mixtures. Arrhenius kinetics scheme was integrated to model the chemical reactions. A locally controlled dissipation was introduced that induces a non-oscillatory stabilized scheme for the shock front. The FE model was validated using analytical solutions for sod shock and ZND strong detonation models and then used to perform 2D and 3D shock simulations. We will present benchmark problems for geometries in which a single HMX crystal is subjected to a shock condition. Our current progress towards developing microstructural models of HMX/binder composite will also be discussed.

Simulating Initial and Progressive Failure of Open-Hole Composite Laminates under Tension

NASA Astrophysics Data System (ADS)

Guo, Zhangxin; Zhu, Hao; Li, Yongcun; Han, Xiaoping; Wang, Zhihua

2016-12-01

A finite element (FE) model is developed for the progressive failure analysis of fiber reinforced polymer laminates. The failure criterion for fiber and matrix failure is implemented in the FE code Abaqus using user-defined material subroutine UMAT. The gradual degradation of the material properties is controlled by the individual fracture energies of fiber and matrix. The failure and damage in composite laminates containing a central hole subjected to uniaxial tension are simulated. The numerical results show that the damage model can be used to accurately predicte the progressive failure behaviour both qualitatively and quantitatively.

Wound ballistics of the pig mandibular angle: a preliminary finite element analysis and experimental study.

PubMed

Chen, Yubin; Miao, Yingyun; Xu, Chuan; Zhang, Gang; Lei, Tao; Tan, Yinghui

2010-04-19

To study wound ballistics of the mandibular angle, a combined hexahedral-tetrahedral finite element (FE) model of the pig mandible was developed to simulate ballistic impact. An experimental study was carried out by measuring impact load parameters from 14 fresh pig mandibles that were shot at the mandibular angle by a standard 7.62 mm M43 bullet. FE analysis was executed through the LS-DYNA code under impact loads similar to those obtained from the experimental study. The resulting residual velocity, the transferred energy from the bullet to the mandible, and the surface area of the entrance wound had no statistical differences between the FE simulation and the experimental study. However, the mean surface area of the exit wounds in the experimental study was significantly larger than that in the simulation. According to the FE analysis, the stress concentrated zones were mainly located at the region of impact, condylar neck, coronoid process and mandibular body. The simulation results also indicated that trabecular bone had less stress concentration and a lower speed of stress propagation compared with cortical bone. The FE model is appropriate and conforms to the basic principles of wound ballistics. This modeling system will be helpful for further investigations of the biomechanical mechanisms of wound ballistics. Copyright 2009 Elsevier Ltd. All rights reserved.

Mechanical behaviour of a fibrous scaffold for ligament tissue engineering: finite elements analysis vs. X-ray tomography imaging.

PubMed

Laurent, Cédric P; Latil, Pierre; Durville, Damien; Rahouadj, Rachid; Geindreau, Christian; Orgéas, Laurent; Ganghoffer, Jean-François

2014-12-01

The use of biodegradable scaffolds seeded with cells in order to regenerate functional tissue-engineered substitutes offers interesting alternative to common medical approaches for ligament repair. Particularly, finite element (FE) method enables the ability to predict and optimise both the macroscopic behaviour of these scaffolds and the local mechanic signals that control the cell activity. In this study, we investigate the ability of a dedicated FE code to predict the geometrical evolution of a new braided and biodegradable polymer scaffold for ligament tissue engineering by comparing scaffold geometries issued from FE simulations and from X-ray tomographic imaging during a tensile test. Moreover, we compare two types of FE simulations the initial geometries of which are issued either from X-ray imaging or from a computed idealised configuration. We report that the dedicated FE simulations from an idealised reference configuration can be reasonably used in the future to predict the global and local mechanical behaviour of the braided scaffold. A valuable and original dialog between the fields of experimental and numerical characterisation of such fibrous media is thus achieved. In the future, this approach should enable to improve accurate characterisation of local and global behaviour of tissue-engineering scaffolds. Copyright © 2014 Elsevier Ltd. All rights reserved.

Type IV pili of Acidithiobacillus ferrooxidans can transfer electrons from extracellular electron donors.

PubMed

Li, Yongquan; Li, Hongyu

2014-03-01

Studies on Acidithiobacillus ferrooxidans accepting electrons from Fe(II) have previously focused on cytochrome c. However, we have discovered that, besides cytochrome c, type IV pili (Tfp) can transfer electrons. Here, we report conduction by Tfp of A. ferrooxidans analyzed with a conducting-probe atomic force microscope (AFM). The results indicate that the Tfp of A. ferrooxidans are highly conductive. The genome sequence of A. ferrooxidans ATCC 23270 contains two genes, pilV and pilW, which code for pilin domain proteins with the conserved amino acids characteristic of Tfp. Multiple alignment analysis of the PilV and PilW (pilin) proteins indicated that pilV is the adhesin gene while pilW codes for the major protein element of Tfp. The likely function of Tfp is to complete the circuit between the cell surface and Fe(II) oxides. These results indicate that Tfp of A. ferrooxidans might serve as biological nanowires transferring electrons from the surface of Fe(II) oxides to the cell surface. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Analysis of cylindrical wrap-around and doubly conformal patch antennas by way of the finite element-artificial absorber method

NASA Technical Reports Server (NTRS)

Volakis, J. L.; Kempel, L. C.; Sliva, R.; Wang, H. T. G.; Woo, A. G.

1994-01-01

The goal of this project was to develop analysis codes for computing the scattering and radiation of antennas on cylindrically and doubly conformal platforms. The finite element-boundary integral (FE-BI) method has been shown to accurately model the scattering and radiation of cavity-backed patch antennas. Unfortunately extension of this rigorous technique to coated or doubly curved platforms is cumbersome and inefficient. An alternative approximate approach is to employ an absorbing boundary condition (ABC) for terminating the finite element mesh thus avoiding use of a Green's function. A FE-ABC method is used to calculate the radar cross section (RCS) and radiation pattern of a cavity-backed patch antenna which is recessed within a metallic surface. It is shown that this approach is accurate for RCS and antenna pattern calculations with an ABC surface displaced as little as 0.3 lambda from the cavity aperture. These patch antennas may have a dielectric overlay which may also be modeled with this technique.

Numerical calculation of the neoclassical electron distribution function in an axisymmetric torus

NASA Astrophysics Data System (ADS)

Lyons, B. C.; Jardin, S. C.; Ramos, J. J.

2011-10-01

We solve for a stationary, axisymmetric electron distribution function (fe) in a torus using a drift-kinetic equation (DKE) with complete Landau collision operator. All terms are kept to gyroradius and collisionality orders relevant to high- temperature tokamaks (i.e., the neoclassical banana regime for electrons). A solubility condition on the DKE determines the non-Maxwellian pieces of fe (called fNMe) to all relevant orders. We work in a 4D phase space (ψ , θ , v , λ) , where ψ defines a flux surface, θ is the poloidal angle, v is the total velocity, and λ is the pitch angle parameter. We expand fNMe in finite elements in both v and λ. The Rosenbluth potentials, Φ and Ψ, which define the collision operator, are expanded in Legendre series in cos χ , where χ is the pitch angle, Fourier series in cos θ , and finite elements in v. At each ψ, we solve a block tridiagonal system for fNMe, Φ, and Ψ simultaneously, resulting in a neoclassical fe for the entire torus. Our goal is to demonstrate that such a formulation can be accurately and efficiently solved numerically. Results will be compared to other codes (e.g., NCLASS, NEO) and could be used as a kinetic closure for an MHD code (e.g., M3D-C1). Supported by the DOE SCGF and DOE Contract # DE-AC02-09CH11466. Based on analytic work by Ramos, PoP 17, 082502 (2010).

Aeroelastic-Acoustics Simulation of Flight Systems

NASA Technical Reports Server (NTRS)

Gupta, kajal K.; Choi, S.; Ibrahim, A.

2009-01-01

This paper describes the details of a numerical finite element (FE) based analysis procedure and a resulting code for the simulation of the acoustics phenomenon arising from aeroelastic interactions. Both CFD and structural simulations are based on FE discretization employing unstructured grids. The sound pressure level (SPL) on structural surfaces is calculated from the root mean square (RMS) of the unsteady pressure and the acoustic wave frequencies are computed from a fast Fourier transform (FFT) of the unsteady pressure distribution as a function of time. The resulting tool proves to be unique as it is designed to analyze complex practical problems, involving large scale computations, in a routine fashion.

Continuum damage model for ferroelectric materials and its application to multilayer actuators

NASA Astrophysics Data System (ADS)

Gellmann, Roman; Ricoeur, Andreas

2016-05-01

In this paper a micromechanical continuum damage model for ferroelectric materials is presented. As a constitutive law it is implemented into a finite element (FE) code. The model is based on micromechanical considerations of domain switching and its interaction with microcrack growth and coalescence. A FE analysis of a multilayer actuator is performed, showing the initiation of damage zones at the electrode tips during the poling process. Further, the influence of mechanical pre-stressing on damage evolution and actuating properties is investigated. The results provided in this work give useful information on the damage of advanced piezoelectric devices and their optimization.

Radiative Rates for Forbidden Transitions in Doubly-Ionized Fe-Peak Elements

NASA Astrophysics Data System (ADS)

Fivet, Vanessa; Quinet, P.; Bautista, M.

2012-05-01

Accurate and reliable atomic data for lowly-ionized Fe-peak species (Sc, Ti, V, Cr, Mn, Fe, Co, Ni and Cu) are of paramount importance for the analysis of the high resolution astrophysical spectra currently available. The third spectra of several iron group elements have been observed in different galactic sources like Herbig-Haro objects in the Orion Nebula [1] and stars like Eta Carinae [2]. However, forbidden transitions between low-lying metastable levels of doubly-ionized iron-peak ions have been very little investigated so far and radiative rates for those lines remain sparse or inexistent. We are carrying out a systematic study of the electronic structure of doubly-ionized iron-peak elements. The magnetic dipole (M1) and electric quadrupole (E2) transition probabilities are computed using the pseudo-relativistic Hartree-Fock (HFR) code of Cowan [3] and the central Thomas-Fermi-Dirac potential approximation implemented in AUTOSTRUCTURE [4]. This multi-platform approach allows for consistency checks and intercomparison and has proven very successful in the study of the complex Fe-peak species where many different effects contribute [5]. References [1] A. Mesa-Delgado et al., MNRAS 395 (2009) 855 [2] S. Johansson et al., A&A 361 (2000) 977 [3] R.D. Cowan, The Theory of Atomic Structure and Spectra, Berkeley: Univ. California Press (1981) [4] N.R. Badnell, J. Phys. B: At. Mol. Opt. Phys. 30 (1997) 1 [5] M. Bautista et al., ApJ 718 (2010) L189

3D Simulations of Supernova Remnants from Type Ia Supernova Models

NASA Astrophysics Data System (ADS)

Johnson, Heather; Reynolds, S. P.; Frohlich, C.; Blondin, J. M.

2014-01-01

Type Ia supernovae (SNe) originate from thermonuclear explosions of white dwarfs. A great deal is still unknown about the explosion mechanisms, particularly the degree of asymmetry. However, Type Ia supernova remnants (SNRs) can bear the imprint of asymmetry long after the explosion. A SNR of interest is G1.9+0.3, the youngest Galactic SNR, which demonstrates an unusual spatial distribution of elements in the ejecta. While its X-ray spectrum is dominated by synchrotron emission, spectral lines of highly ionized Si, S, and Fe are seen in a few locations, with Fe near the edge of the remnant and with strongly varying Fe/Si ratios. An asymmetric explosion within the white dwarf progenitor may be necessary to explain these unusual features of G1.9+0.3, in particular the shocked Fe at large radii. We use the VH-1 hydrodynamics code to evolve initial Type Ia explosion models in 1, 2, and 3 dimensions at an age of 100 seconds provided by other researchers to study asymmetry, the ignition properties, and the nucleosynthesis resulting from these explosions. We follow the evolution of these models interacting with a uniform external medium to a few hundred years in age. We find the abundance and location of ejecta elements from our models to be inconsistent with the observations of G1.9+0.3; while our models show asymmetric element distributions, we find no tendency for iron-group elements to be found beyond intermediate-mass elements, or for significant iron to be reverse-shocked at all at the age of G1.9+0.3. We compare the amounts of shocked iron-group and intermediate-mass elements as a function of time in the different models. Some new kind of explosion asymmetry may be required to explain G1.9+0.3. This work was performed as part of NC State University's Undergraduate Research in Computational Astrophysics (URCA) program, an REU program supported by the National Science Foundation through award AST-1032736.

First principles study of the ground state properties of Si, Ga, and Ge doped Fe50Al50

NASA Astrophysics Data System (ADS)

Pérez, Carlos Ariel Samudio; dos Santos, Antonio Vanderlei

2018-06-01

The first principles calculation of the structural, electronic and associated properties of the Fe50Al50 alloy (B2 phase) doped by s-p elements (Im = Si, Ga, and Ge) are performed as a function of the atomic concentration on the basis of the Full Potential Linear Augmented Plane Wave (FP-LAPW) method as implemented in the WIEN2k code. The Al substitution by Im (Si and Ge) atoms (principally at a concentration of 6.25 at%) induces a pronounced redistribution of the electronic charge leading to a strong Fe-Im interaction with covalent bonding character. At the same time, decrease the lattice volume (V) while increase the bulk modulus (B). For the alloys containing Ga, the Fe-Ga interaction is also observed but the V and B of the alloy are very near to that of pure Fe-Al alloy. The magnetic moment and hyperfine parameters observed at the lattice sites of studied alloys also show variations, they increase or decrease in relation to that in Fe50Al50 according to the Im that substitutes Al.

Parallel Computation of the Jacobian Matrix for Nonlinear Equation Solvers Using MATLAB

NASA Technical Reports Server (NTRS)

Rose, Geoffrey K.; Nguyen, Duc T.; Newman, Brett A.

2017-01-01

Demonstrating speedup for parallel code on a multicore shared memory PC can be challenging in MATLAB due to underlying parallel operations that are often opaque to the user. This can limit potential for improvement of serial code even for the so-called embarrassingly parallel applications. One such application is the computation of the Jacobian matrix inherent to most nonlinear equation solvers. Computation of this matrix represents the primary bottleneck in nonlinear solver speed such that commercial finite element (FE) and multi-body-dynamic (MBD) codes attempt to minimize computations. A timing study using MATLAB's Parallel Computing Toolbox was performed for numerical computation of the Jacobian. Several approaches for implementing parallel code were investigated while only the single program multiple data (spmd) method using composite objects provided positive results. Parallel code speedup is demonstrated but the goal of linear speedup through the addition of processors was not achieved due to PC architecture.

EXPLORING ANTICORRELATIONS AND LIGHT ELEMENT VARIATIONS IN NORTHERN GLOBULAR CLUSTERS OBSERVED BY THE APOGEE SURVEY

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

Mészáros, Szabolcs; Martell, Sarah L.; Shetrone, Matthew

We investigate the light-element behavior of red giant stars in northern globular clusters (GCs) observed by the SDSS-III Apache Point Observatory Galactic Evolution Experiment. We derive abundances of 9 elements (Fe, C, N, O, Mg, Al, Si, Ca, and Ti) for 428 red giant stars in 10 GCs. The intrinsic abundance range relative to measurement errors is examined, and the well-known C–N and Mg–Al anticorrelations are explored using an extreme-deconvolution code for the first time in a consistent way. We find that Mg and Al drive the population membership in most clusters, except in M107 and M71, the two mostmore » metal-rich clusters in our study, where the grouping is most sensitive to N. We also find a diversity in the abundance distributions, with some clusters exhibiting clear abundance bimodalities (for example M3 and M53) while others show extended distributions. The spread of Al abundances increases significantly as cluster average metallicity decreases as previously found by other works, which we take as evidence that low metallicity, intermediate mass AGB polluters were more common in the more metal-poor clusters. The statistically significant correlation of [Al/Fe] with [Si/Fe] in M15 suggests that {sup 28}Si leakage has occurred in this cluster. We also present C, N, and O abundances for stars cooler than 4500 K and examine the behavior of A(C+N+O) in each cluster as a function of temperature and [Al/Fe]. The scatter of A(C+N+O) is close to its estimated uncertainty in all clusters and independent of stellar temperature. A(C+N+O) exhibits small correlations and anticorrelations with [Al/Fe] in M3 and M13, but we cannot be certain about these relations given the size of our abundance uncertainties. Star-to-star variations of α-element (Si, Ca, Ti) abundances are comparable to our estimated errors in all clusters.« less

Exploring Anticorrelations and Light Element Variations in Northern Globular Clusters Observed by the APOGEE Survey

NASA Astrophysics Data System (ADS)

Mészáros, Szabolcs; Martell, Sarah L.; Shetrone, Matthew; Lucatello, Sara; Troup, Nicholas W.; Bovy, Jo; Cunha, Katia; García-Hernández, Domingo A.; Overbeek, Jamie C.; Allende Prieto, Carlos; Beers, Timothy C.; Frinchaboy, Peter M.; García Pérez, Ana E.; Hearty, Fred R.; Holtzman, Jon; Majewski, Steven R.; Nidever, David L.; Schiavon, Ricardo P.; Schneider, Donald P.; Sobeck, Jennifer S.; Smith, Verne V.; Zamora, Olga; Zasowski, Gail

2015-05-01

We investigate the light-element behavior of red giant stars in northern globular clusters (GCs) observed by the SDSS-III Apache Point Observatory Galactic Evolution Experiment. We derive abundances of 9 elements (Fe, C, N, O, Mg, Al, Si, Ca, and Ti) for 428 red giant stars in 10 GCs. The intrinsic abundance range relative to measurement errors is examined, and the well-known C-N and Mg-Al anticorrelations are explored using an extreme-deconvolution code for the first time in a consistent way. We find that Mg and Al drive the population membership in most clusters, except in M107 and M71, the two most metal-rich clusters in our study, where the grouping is most sensitive to N. We also find a diversity in the abundance distributions, with some clusters exhibiting clear abundance bimodalities (for example M3 and M53) while others show extended distributions. The spread of Al abundances increases significantly as cluster average metallicity decreases as previously found by other works, which we take as evidence that low metallicity, intermediate mass AGB polluters were more common in the more metal-poor clusters. The statistically significant correlation of [Al/Fe] with [Si/Fe] in M15 suggests that 28Si leakage has occurred in this cluster. We also present C, N, and O abundances for stars cooler than 4500 K and examine the behavior of A(C+N+O) in each cluster as a function of temperature and [Al/Fe]. The scatter of A(C+N+O) is close to its estimated uncertainty in all clusters and independent of stellar temperature. A(C+N+O) exhibits small correlations and anticorrelations with [Al/Fe] in M3 and M13, but we cannot be certain about these relations given the size of our abundance uncertainties. Star-to-star variations of α-element (Si, Ca, Ti) abundances are comparable to our estimated errors in all clusters.

Damage percolation during stretch flange forming of aluminum alloy sheet

NASA Astrophysics Data System (ADS)

Chen, Zengtao; Worswick, Michael J.; Keith Pilkey, A.; Lloyd, David J.

2005-12-01

A multi-scale finite element (FE)-damage percolation model was employed to simulate stretch flange forming of aluminum alloys AA5182 and AA5754. Material softening and strain gradients were captured using a Gurson-based FE model. FE results were then fed into the so-called damage percolation code, from which the damage development was modelled within measured microstructures. The formability of the stretch flange samples was predicted based upon the onset of catastrophic failure triggered by profuse void coalescence within the measured second-phase particle field. Damage development is quantified in terms of crack and void areal fractions, and compared to metallographic results obtained from interrupted stretch flange specimens. Parametric study is conducted on the effect of void nucleation strain in the prediction of formability of stretch flanges to "calibrate" proper nucleation strains for both alloys.

Deformation behaviour of Rheocast A356 Al alloy at microlevel considering approximated RVEs

NASA Astrophysics Data System (ADS)

Islam, Sk. Tanbir; Das, Prosenjit; Das, Santanu

2015-03-01

A micromechanical approach is considered here to predict the deformation behaviour of Rheocast A356 (Al-Si-Mg) alloy. Two representative volume elements (RVEs) are modelled in the finite element (FE) framework. Two dimensional approximated microstructures are generated assuming elliptic grains, based on the grain size, shape factor and area fraction of the primary Al phase of the said alloy at different processing condition. Plastic instability is shown using stress and strain distribution between the Al rich primary and Si rich eutectic phases under different boundary conditions. Boundary conditions are applied on the approximated RVEs in such a manner, so that they represent the real life situation depending on their position on a cylindrical tensile test sample. FE analysis is carried out using commercial finite element code ABAQUS without specifying any damage or failure criteria. Micro-level in-homogeneity leads to incompatible deformation between the constituent phases of the rheocast alloy and steers plastic strain localisation. Plastic stain localised regions within the RVEs are predicted as the favourable sites for void nucleation. Subsequent growth of nucleated voids leads to final failure of the materials under investigation.

Analysis of Ninety Degree Flexure Tests for Characterization of Composite Transverse Tensile Strength

NASA Technical Reports Server (NTRS)

OBrien, T. Kevin; Krueger, Ronald

2001-01-01

Finite element (FE) analysis was performed on 3-point and 4-point bending test configurations of ninety degree oriented glass-epoxy and graphite-epoxy composite beams to identify deviations from beam theory predictions. Both linear and geometric non-linear analyses were performed using the ABAQUS finite element code. The 3-point and 4-point bending specimens were first modeled with two-dimensional elements. Three-dimensional finite element models were then performed for selected 4-point bending configurations to study the stress distribution across the width of the specimens and compare the results to the stresses computed from two-dimensional plane strain and plane stress analyses and the stresses from beam theory. Stresses for all configurations were analyzed at load levels corresponding to the measured transverse tensile strength of the material.

Vertical Geochemical Variations and Speciation Studies of As, Fe, Mn, Zn, and Cu in the Sediments of the Central Gangetic Basin: Sequential Extraction and Statistical Approach

PubMed Central

Ramanathan, AL.

2018-01-01

A geochemical and speciation study of As, Fe, Mn, Zn, and Cu was performed using sequential extraction and statistical approaches in the core sediments taken at two locations—Rigni Chhapra and Chaube Chhapra—of the central Gangetic basin (India). A gradual increase in the grain size (varying from clay to coarse sands) was observed in both the core profiles up to 30.5 m depth. The concentrations of analyzed elements ranged as follows: 6.9–14.2 mg/kg for As, 13,849–31,088 mg/kg for Fe, 267–711 mg/kg for Mn, 45–164 mg/kg for Cu for Rigni Chhapra while for Chaube Chhapra the range was 7.5–13.2 mg/kg for As, 10,936–37,052 mg/kg for Fe, 267–1052 mg/kg for Mn, 60–198 mg/kg for Zn and 60–108 mg/kg for Cu. Significant amounts (53–95%) of all the fractionated elemental concentrations were bound within the crystal structure of the minerals as a residual fraction. The reducible fraction was the second most dominant fraction for As (7% and 8%), Fe (3%), Mn (20% and 26%), and Cu (7% and 6%) respectively for both the cores. It may be released when aquifers subjected to changing redox conditions. The acid soluble fraction was of most interest because it could quickly mobilize into the water system which formed the third most dominating among all three fractions. Four color code of sediments showed an association with total As concentration and did not show a relation with any fraction of all elements analyzed. The core sediment was observed enriched with As and other elements (Cu, Fe, Mn, and Zn). However, it fell under uncontaminated to moderately contaminate which might exhibit a low risk in prevailing natural conditions. X-ray diffraction analyses indicated the availability of siderite and magnetite minerals in the core sediments in a section of dark grey with micaceous medium sand with organic matter (black). PMID:29360767

Project VeSElkA: abundance analysis of chemical species in HD 41076 and HD 148330

NASA Astrophysics Data System (ADS)

Khalack, V.; Gallant, G.; Thibeault, C.

2017-10-01

A new semi-automatic approach is employed to carry out the abundance analysis of high-resolution spectra of HD 41076 and HD 148330 obtained recently with the spectropolarimetre Echelle SpectroPolarimetric Device for Observations of Stars at the Canada-France-Hawaii Telescope. This approach allows to prepare in a semi-automatic mode the input data for the modified zeeman2 code and to analyse several hundreds of line profiles in sequence during a single run. It also provides more information on abundance distribution for each chemical element at the deeper atmospheric layers. Our analysis of the Balmer profiles observed in the spectra of HD 41076 and HD 148330 has resulted in the estimates of their effective temperature, gravity, metallicity and radial velocity. The respective models of stellar atmosphere have been calculated with the code phoenix and used to carry out abundance analysis employing the modified zeeman2 code. The analysis shows a deficit of the C, N, F, Mg, Ca, Ti, V, Cu, Y, Mo, Sm and Gd, and overabundance of Cr, Mn, Fe, Co, Ni, Sr, Zr, Ba, Ce, Nd and Dy in the stellar atmosphere of HD 41076. In the atmosphere of HD 148330, the C, N and Mo appear to be underabundant, while the Ne, Na, Al, Si, P, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Sr, Y, Zr, Ba, Ce, Pr, Nd, Sm, Eu, Gd and Dy are overabundant. We also have found signatures of vertical abundance stratification of Fe, Ti, Cr and Mn in HD 41076, and of Fe, Ti, V, Cr, Mn, Y, Zr, Ce, Nd, Sm and Gd in HD 148330.

Mg, Al, Si, Ca, Ti, Fe, and Ni abundance for a sample of solar analogues

NASA Astrophysics Data System (ADS)

López-Valdivia, Ricardo; Bertone, Emanuele; Chávez, Miguel

2017-05-01

We report on the determination of chemical abundances of 38 solar analogues, including 11 objects previously identified as super-metal-rich stars. We have measured the equivalent widths for 34 lines of 7 different chemical elements (Mg, Al, Si, Ca, Ti, Fe and Ni) in high-resolution (R ˜ 80 000) spectroscopic images, obtained at the Observatorio Astrofísico Guillermo Haro (Sonora, Mexico), with the Cananea High-resolution Spectrograph. We derived chemical abundances using atlas12 model atmospheres and the Fortran code moog. We confirmed the super-metallicity status of six solar analogues. Within our sample, BD+60 600 is the most metal rich star ([Fe/H] = +0.35 dex), while for HD 166991, we obtained the lowest iron abundance ([Fe/H] = -0.53 dex). We also computed the so-called [Ref] index for 25 of our solar analogues, and we found that BD+60 600 ([Ref] = +0.42) and BD+28 3198 ([Ref] = +0.34) are good targets for exoplanet search.

GPGPU-based explicit finite element computations for applications in biomechanics: the performance of material models, element technologies, and hardware generations.

PubMed

Strbac, V; Pierce, D M; Vander Sloten, J; Famaey, N

2017-12-01

Finite element (FE) simulations are increasingly valuable in assessing and improving the performance of biomedical devices and procedures. Due to high computational demands such simulations may become difficult or even infeasible, especially when considering nearly incompressible and anisotropic material models prevalent in analyses of soft tissues. Implementations of GPGPU-based explicit FEs predominantly cover isotropic materials, e.g. the neo-Hookean model. To elucidate the computational expense of anisotropic materials, we implement the Gasser-Ogden-Holzapfel dispersed, fiber-reinforced model and compare solution times against the neo-Hookean model. Implementations of GPGPU-based explicit FEs conventionally rely on single-point (under) integration. To elucidate the expense of full and selective-reduced integration (more reliable) we implement both and compare corresponding solution times against those generated using underintegration. To better understand the advancement of hardware, we compare results generated using representative Nvidia GPGPUs from three recent generations: Fermi (C2075), Kepler (K20c), and Maxwell (GTX980). We explore scaling by solving the same boundary value problem (an extension-inflation test on a segment of human aorta) with progressively larger FE meshes. Our results demonstrate substantial improvements in simulation speeds relative to two benchmark FE codes (up to 300[Formula: see text] while maintaining accuracy), and thus open many avenues to novel applications in biomechanics and medicine.

Impact of inflammation on iron stores in involved and non-involved psoriatic skin

NASA Astrophysics Data System (ADS)

Pinheiro, T.; Ynsa, M. D.; Alves, L. C.; Teixeira, P.; Ferreira, J.; Filipe, P.

2015-04-01

Accumulating evidence supports a role for cellular Fe in cell proliferation, inflammation, and disease tolerance. Psoriasis is a severe inflammatory and hyper proliferative condition of human skin whose aetiology remains poorly understood. Herein, we performed nuclear microscopy techniques to quantify with cellular resolution and high sensitivity the concentration of Fe in lesional (psoriatic plaques) and non-lesional adjacent skin of psoriatic patients. Fe contents were measured across skin depth and along epidermal strata either by quantitatively imaging Fe distribution in regions of interest, or by determining Fe profiles through analysis of sequential points along selected transepts. Both procedures require deconvolution of spectra to project quantitative elemental data through the application of different software codes. Using these approaches a detailed quantitative distribution of Fe was resolved. We show that in both lesional and non-lesional skin, the epidermal profiles of Fe contents showed a peak at the basal layer and that Fe concentration along the basal layer was not uniformly distributed. Typically, Fe levels were significantly higher in epidermal ridges relative to regions above dermal papillae. Lesional skin displayed excess Fe over extended regions above basal layer. In conclusion, we found significantly increased Fe deposits in the epidermis of psoriatic patients, particularly in areas of epidermal hyper proliferation. These findings suggest an important role for Fe in the pathogenesis of psoriasis. They also raise the possibility that manipulation of Fe levels in the skin may become relevant for the clinical management of psoriasis.

Characterization of the Acoustic Radiation Properties of Laminated and Sandwich Composite Panels in Thermal Environment

NASA Astrophysics Data System (ADS)

Sharma, Nitin; Ranjan Mahapatra, Trupti; Panda, Subrata Kumar; Sahu, Pruthwiraj

2018-03-01

In this article, the acoustic radiation characteristics of laminated and sandwich composite spherical panels subjected to harmonic point excitation under thermal environment are investigated. The finite element (FE) simulation model of the vibrating panel structure is developed in ANSYS using ANSYS parametric design language (APDL) code. Initially, the critical buckling temperatures of the considered structures are obtained and the temperature loads are assorted accordingly. Then, the modal analysis of the thermally stressed panels is performed and the thermo-elastic free vibration responses so obtained are validated with the benchmark solutions. Subsequently, an indirect boundary element (BE) method is utilized to conduct a coupled FE-BE analysis to compute the sound radiation properties of panel structure. The agreement of the present sound power responses with the existing results available in the published literature establishes the validity of the proposed scheme. Finally, the current standardised scheme is extended to solve several numerical examples to bring out the influence of various parameters on the thermo-acoustic characteristics of laminated composite panels.

The origin and evolution of r- and s-process elements in the Milky Way stellar disk

NASA Astrophysics Data System (ADS)

Battistini, Chiara; Bensby, Thomas

2016-02-01

Context. Elements heavier than iron are produced through neutron-capture processes in the different phases of stellar evolution. Asymptotic giant branch (AGB) stars are believed to be mainly responsible for elements that form through the slow neutron-capture process, while the elements created in the rapid neutron-capture process have production sites that are less understood. Knowledge of abundance ratios as functions of metallicity can lead to insight into the origin and evolution of our Galaxy and its stellar populations. Aims: We aim to trace the chemical evolution of the neutron-capture elements Sr, Zr, La, Ce, Nd, Sm, and Eu in the Milky Way stellar disk. This will allow us to constrain the formation sites of these elements, as well as to probe the evolution of the Galactic thin and thick disks. Methods: Using spectra of high resolution (42 000 ≲ R ≲ 65 000) and high signal-to-noise (S/N ≳ 200) obtained with the MIKE and the FEROS spectrographs, we determine Sr, Zr, La, Ce, Nd, Sm, and Eu abundances for a sample of 593 F and G dwarf stars in the solar neighborhood. The abundance analysis is based on spectral synthesis using one-dimensional, plane-parallel, local thermodynamic equilibrium (LTE) model stellar atmospheres calculated with the MARCS 2012 code. Results: We present abundance results for Sr (156 stars), Zr (311 stars), La (242 stars), Ce (365 stars), Nd (395 stars), Sm (280 stars), and Eu (378 stars). We find that Nd, Sm, and Eu show trends similar to what is observed for the α elements in the [X/Fe]-[Fe/H] abundance plane. For [Sr/Fe] and [Zr/Fe], we find decreasing abundance ratios for increasing metallicity, reaching sub-solar values at super-solar metallicities. [La/Fe] and [Ce/Fe] do not show any clear trend with metallicity, and they are close to solar values at all [Fe/H]. The trends of abundance ratios [X/Fe] as a function of stellar ages present different slopes before and after 8 Gyr. Conclusions: The rapid neutron-capture process is active early in the Galaxy, mainly in type-II supernovae from stars in the mass range 8-10 M⊙. Europium is almost completely produced by the r-process, but Nd and Sm show similar trends to Eu even if their s-process component is higher. Strontium and Zr are thought to be mainly produced by the s-process, but show significant enrichment at low metallicity that requires extra r-process production, which probably is different from the classical r-process. Finally, La and Ce are mainly produced via s-process from AGB stars in the mass range 2-4 M⊙, which can be seen by the decrease in [La/Eu] and [Ce/Eu] at [Fe/H] ≈ -0.5. The trend of [X/Fe] with age could be explained by considering that the decrease in [X/Fe] for the thick disk stars can be due to the decrease in type-II supernovae with time, meaning a reduced enrichment of r-process elements in the interstellar medium. In the thin disk, the trends are flatter, which is probably due to the main production from the s-process being balanced by Fe production from type-Ia supernovae. This paper includes data gathered with the 6.5 m Magellan Telescopes at the Las Campanas Observatory, Chile and the ESO 1.5-m, 2.2-m. and 3.6-m telescopes on La Silla, Chile (ESO Proposal ID 65.L-0019, 67.B-0108, 76.B-0416, 82.B-0610); and data from UVES Paranal Observatory Project (ESO DDT Program ID 266.D-5655).Full Tables 3 and 4 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/586/A49

Calculation of Free-Atom Fractions in Hydrocarbon-Fueled Rocket Engine Plume

NASA Technical Reports Server (NTRS)

Verma, Satyajit

2006-01-01

Free atom fractions (Beta) of nine elements are calculated in the exhaust plume of CH4- oxygen and RP-1-oxygen fueled rocket engines using free energy minimization method. The Chemical Equilibrium and Applications (CEA) computer program developed by the Glenn Research Center, NASA is used for this purpose. Data on variation of Beta in both fuels as a function of temperature (1600 K - 3100 K) and oxygen to fuel ratios (1.75 to 2.25 by weight) is presented in both tabular and graphical forms. Recommendation is made for the Beta value for a tenth element, Palladium. The CEA computer code was also run to compare with experimentally determined Beta values reported in literature for some of these elements. A reasonable agreement, within a factor of three, between the calculated and reported values is observed. Values reported in this work will be used as a first approximation for pilot rocket engine testing studies at the Stennis Space Center for at least six elements Al, Ca, Cr, Cu, Fe and Ni - until experimental values are generated. The current estimates will be improved when more complete thermodynamic data on the remaining four elements Ag, Co, Mn and Pd are added to the database. A critique of the CEA code is also included.

Quantitative analysis of biomedical samples using synchrotron radiation microbeams

NASA Astrophysics Data System (ADS)

Ektessabi, Ali; Shikine, Shunsuke; Yoshida, Sohei

2001-07-01

X-ray fluorescence (XRF) using a synchrotron radiation (SR) microbeam was applied to investigate distributions and concentrations of elements in single neurons of patients with neurodegenerative diseases. In this paper we introduce a computer code that has been developed to quantify the trace elements and matrix elements at the single cell level. This computer code has been used in studies of several important neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD) and parkinsonism-dementia complex (PDC), as well as in basic biological experiments to determine the elemental changes in cells due to incorporation of foreign metal elements. The substantial nigra (SN) tissue obtained from the autopsy specimens of patients with Guamanian parkinsonism-dementia complex (PDC) and control cases were examined. Quantitative XRF analysis showed that neuromelanin granules of Parkinsonian SN contained higher levels of Fe than those of the control. The concentrations were in the ranges of 2300-3100 ppm and 2000-2400 ppm respectively. On the contrary, Zn and Ni in neuromelanin granules of SN tissue from the PDC case were lower than those of the control. Especially Zn was less than 40 ppm in SN tissue from the PDC case while it was 560-810 ppm in the control. These changes are considered to be closely related to the neuro-degeneration and cell death.

Interpreting ASME limits and philosophy in FEA of pressure vessel parts

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

Bezerra, L.M.; Cruz, J.R.B.; Miranda, C.A.J.

1995-12-01

In recent years there has been an effort to interpret finite element (FE) stress results on the light of the ASME B and PV rules and philosophy. Many task groups have issued guidelines on stress linearization and classifications. All those attempts have come up trying to cope modern FE techniques with the rules imposed by the ASME Code. This paper is an independent contribution to the Pressure Vessel Research Council (PVRC) groups which are studying the stress classification and the failure mechanism in a FE framework. This work tries to complement the interesting work by Hollinger and Hechmer presented inmore » the PVP-94 in Minneapolis. In that paper, the authors examined a typical support skirt and showed relations between the skirt collapse load obtained by finite element analysis and the loads allowed from the ASME stress limits. To complement such paper, in the present article, different skirt geometry configurations are analyzed. The configurations here investigated consist of similar support skirts but with different angles of attachments between cylinder and cone parts. It will be possible to observe the influence of the bending stress in the collapse load and its relation to the allowable loads inferred from the ASME limits. A pressure vessel with torispherical head under internal pressure is also examined. Using elastic and limit load FEA, the present paper determines the collapse loads of the configurations. It sets up the relations between these collapse loads, stress categories, and limits dictated by the ASME Code Subsection NB. On the light of NB rules and philosophy, this paper shows how different methods of stress assessment, classification, and limits may influence in the design of a pressure vessel.« less

Application of artificial neural network in precise prediction of cement elements percentages based on the neutron activation analysis

NASA Astrophysics Data System (ADS)

Eftekhari Zadeh, E.; Feghhi, S. A. H.; Roshani, G. H.; Rezaei, A.

2016-05-01

Due to variation of neutron energy spectrum in the target sample during the activation process and to peak overlapping caused by the Compton effect with gamma radiations emitted from activated elements, which results in background changes and consequently complex gamma spectrum during the measurement process, quantitative analysis will ultimately be problematic. Since there is no simple analytical correlation between peaks' counts with elements' concentrations, an artificial neural network for analyzing spectra can be a helpful tool. This work describes a study on the application of a neural network to determine the percentages of cement elements (mainly Ca, Si, Al, and Fe) using the neutron capture delayed gamma-ray spectra of the substance emitted by the activated nuclei as patterns which were simulated via the Monte Carlo N-particle transport code, version 2.7. The Radial Basis Function (RBF) network is developed with four specific peaks related to Ca, Si, Al and Fe, which were extracted as inputs. The proposed RBF model is developed and trained with MATLAB 7.8 software. To obtain the optimal RBF model, several structures have been constructed and tested. The comparison between simulated and predicted values using the proposed RBF model shows that there is a good agreement between them.

The Effects of Surface Roughness on the NEAR XRS Elemental Results: Monte-Carlo Modeling

NASA Technical Reports Server (NTRS)

Lin, Lucy F.; Nittler, Larry R.

2011-01-01

The objective of the NEAR-Shoemaker X-ray Gamma-Ray Spec1roscopy ("XGRS") investigation was to determine the elemental composition of the near-Earth asteroid 433 Eros. The X-ray Spectrometer (XRS) system measured the characteristic fluorescence of six major elements (Mg, Al, Si, S, Ca, Fe) in the 1-10 keV energy range excited by the interaction of solar X-rays with the upper 100 microns of the surface of 433 Eros. Various investigators, using both laboratory experiments and computer simulations have established that X-ray fluorescent line ratios can be influenced by small-scale surface roughness at high incidence or emission angles. The effect on the line ratio is specific to the geometry, excitation spectrum, and composition involved, In general, however, the effect is only substantial for ratios of lines with a significant energy difference between them: Fe/Si and Ca/Si are much more likely to be affected than AI/Si or Mg/Si. We apply a Monte-Carlo code to the specific geometry and spectrum of a major NEAR XRS solar flare observation, using an H chondrite composition as the substrate. The seventeen most abundant elements were included in the composition model, from oxygen to titanium.

An Arrhenius-type viscosity function to model sintering using the Skorohod Olevsky viscous sintering model within a finite element code.

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

Ewsuk, Kevin Gregory; Arguello, Jose Guadalupe, Jr.; Reiterer, Markus W.

2006-02-01

The ease and ability to predict sintering shrinkage and densification with the Skorohod-Olevsky viscous sintering (SOVS) model within a finite-element (FE) code have been improved with the use of an Arrhenius-type viscosity function. The need for a better viscosity function was identified by evaluating SOVS model predictions made using a previously published polynomial viscosity function. Predictions made using the original, polynomial viscosity function do not accurately reflect experimentally observed sintering behavior. To more easily and better predict sintering behavior using FE simulations, a thermally activated viscosity function based on creep theory was used with the SOVS model. In comparison withmore » the polynomial viscosity function, SOVS model predictions made using the Arrhenius-type viscosity function are more representative of experimentally observed viscosity and sintering behavior. Additionally, the effects of changes in heating rate on densification can easily be predicted with the Arrhenius-type viscosity function. Another attribute of the Arrhenius-type viscosity function is that it provides the potential to link different sintering models. For example, the apparent activation energy, Q, for densification used in the construction of the master sintering curve for a low-temperature cofire ceramic dielectric has been used as the apparent activation energy for material flow in the Arrhenius-type viscosity function to predict heating rate-dependent sintering behavior using the SOVS model.« less

A finite element model of myocardial infarction using a composite material approach.

PubMed

Haddad, Seyyed M H; Samani, Abbas

2018-01-01

Computational models are effective tools to study cardiac mechanics under normal and pathological conditions. They can be used to gain insight into the physiology of the heart under these conditions while they are adaptable to computer assisted patient-specific clinical diagnosis and therapeutic procedures. Realistic cardiac mechanics models incorporate tissue active/passive response in conjunction with hyperelasticity and anisotropy. Conventional formulation of such models leads to mathematically-complex problems usually solved by custom-developed non-linear finite element (FE) codes. With a few exceptions, such codes are not available to the research community. This article describes a computational cardiac mechanics model developed such that it can be implemented using off-the-shelf FE solvers while tissue pathologies can be introduced in the model in a straight-forward manner. The model takes into account myocardial hyperelasticity, anisotropy, and active contraction forces. It follows a composite tissue modeling approach where the cardiac tissue is decomposed into two major parts: background and myofibers. The latter is modelled as rebars under initial stresses mimicking the contraction forces. The model was applied in silico to study the mechanics of infarcted left ventricle (LV) of a canine. End-systolic strain components, ejection fraction, and stress distribution attained using this LV model were compared quantitatively and qualitatively to corresponding data obtained from measurements as well as to other corresponding LV mechanics models. This comparison showed very good agreement.

Sulfide Melts and Chalcophile Element Behavior in High Temperature Systems

NASA Astrophysics Data System (ADS)

Wood, B. J.; Kiseeva, K.

2016-12-01

We recently found that partition coefficients (Di) of many weakly and moderately chalcophile elements (e.g., Cd, Zn, Co, Cr, Pb, Sb, In) between sulfide and silicate melts are simple functions of the FeO content of the silicate liquid: logDi A-Blog[FeO] where [FeO] is the FeO concentration in the silicate, A and B are constants and the latter is related to the valency of the element of interest. In contrast, some strongly chalcophile (e.g Cu, Ni, Ag) and lithophile elements (e.g Mn) show marked deviations from linearity on a plot of logDi vs log[FeO]. More recent experiments show that linear behavior is confined to elements whose affinities for S and O are similar to those of Fe. In the case of elements more strongly lithophile than Fe (Ti, U, REE, Zr, Nb, Ta, Mn) a plot of logDi versus log[FeO] describes a U-shape with the element partitioning strongly into the sulfide at very low FeO and again at very high FeO content of the silicate melt. In contrast, strongly chalcophile elements (Cu, Ni, Ag) describe an n-shape on the plot of logD vs log[FeO]. The result is that lithophile elements such as Nb become more "chalcophile" than Cu at very low and very high FeO contents of the silicate melt. The reasons for this surprising behavior are firstly that, at very low FeO contents the silicate melt dissolves substantial amounts of sulfur, which drives down the activity of FeO and, from mass-action "pulls" the lihophile element into the sulfide. At high FeO contents of the silicate the sulfide itself starts to dissolve substantial amounts of oxygen and lithophile elements follow the oxygen into the sulfide. Given the principles which we have established, we are able to describe the patterns of chalcophile element behavior during partial melting and fractional crystallisation on Earth and also on bodies such as Mercury and Mars which are, respectively, strongly reduced relative to Earth and more oxidised than Earth.

Investigating Planetesimal Evolution by Experiments with Fe-Ni Metallic Melts: Light Element Composition Effects on Trace Element Partitioning Behavior

NASA Astrophysics Data System (ADS)

Chabot, N. L.

2017-12-01

As planetesimals were heated up in the early Solar System, the formation of Fe-Ni metallic melts was a common occurrence. During planetesimal differentiation, the denser Fe-Ni metallic melts separated from the less dense silicate components, though some meteorites suggest that their parent bodies only experienced partial differentiation. If the Fe-Ni metallic melts did form a central metallic core, the core eventually crystallized to a solid, some of which we sample as iron meteorites. In all of these planetesimal evolution processes, the composition of the Fe-Ni metallic melt influenced the process and the resulting trace element chemical signatures. In particular, the metallic melt's "light element" composition, those elements present in the metallic melt in a significant concentration but with lower atomic masses than Fe, can strongly affect trace element partitioning. Experimental studies have provided critical data to determine the effects of light elements in Fe-Ni metallic melts on trace element partitioning behavior. Here I focus on combining numerous experimental results to identify trace elements that provide unique insight into constraining the light element composition of early Solar System Fe-Ni metallic melts. Experimental studies have been conducted at 1 atm in a variety of Fe-Ni systems to investigate the effects of light elements on trace element partitioning behavior. A frequent experimental examination of the effects of light elements in metallic systems involves producing run products with coexisting solid metal and liquid metal phases. Such solid-metal-liquid-metal experiments have been conducted in the Fe-Ni binary system as well as Fe-Ni systems with S, P, and C. Experiments with O-bearing or Si-bearing Fe-Ni metallic melts do not lend themselves to experiments with coexisting solid metal and liquid metal phases, due to the phase diagrams of these elements, but experiments with two immiscible Fe-Ni metallic melts have provided insight into the qualitative effects of O and Si relative to the well-determined effects of S. Together, these experimental studies provide a robust dataset to identify key elements that are predicted to produce distinct chemical signatures as a function of different Fe-Ni metallic melt compositions during planetesimal evolution processes.

Radiative rates for forbidden M1 and E2 transitions of astrophysical interest in doubly ionized iron-peak elements

NASA Astrophysics Data System (ADS)

Fivet, V.; Quinet, P.; Bautista, M. A.

2016-01-01

Aims: Accurate and reliable atomic data for lowly ionized Fe-peak species (Sc, Ti, V, Cr, Mn, Fe, Co, and Ni) are of paramount importance for analyzing the high-resolution astrophysical spectra currently available. The third spectra of several iron group elements have been observed in different galactic sources, such as Herbig-Haro objects in the Orion Nebula and stars like Eta Carinae. However, forbidden M1 and E2 transitions between low-lying metastable levels of doubly charged iron-peak ions have been investigated very little so far, and radiative rates for those lines remain sparse or nonexistent. We attempt to fill that gap and provide transition probabilities for the most important forbidden lines of all doubly ionized iron-peak elements. Methods: We carried out a systematic study of the electronic structure of doubly ionized Fe-peak species. The magnetic dipole (M1) and electric quadrupole (E2) transition probabilities were computed using the pseudo-relativistic Hartree-Fock (HFR) code of Cowan and the central Thomas-Fermi-Dirac-Amaldi potential approximation implemented in AUTOSTRUCTURE. This multiplatform approach allowed for consistency checks and intercomparison and has proven very useful in many previous works for estimating the uncertainties affecting the radiative data. Results: We present transition probabilities for the M1 and E2 forbidden lines depopulating the metastable even levels belonging to the 3dk and 3dk-14s configurations in Sc III (k = 1), Ti III (k = 2), V III (k = 3), Cr III (k = 4), Mn III (k = 5), Fe III (k = 6), Co III (k = 7), and Ni III (k = 8).

Metal-fluxes characterization at a catchment scale: Study of mixing processes and end-member analysis in the Meca River watershed (SW Spain)

NASA Astrophysics Data System (ADS)

Cánovas, C. R.; Macías, F.; Olías, M.; López, R. Pérez; Nieto, J. M.

2017-07-01

Fluxes of acidity and contaminants from acid mine drainage (AMD) sources to the receiving surface water bodies were studied in a mining-impacted watershed (Meca River, SW Spain) using a novel methodology based on the joint application of EMMA and MIX codes. The application of EMMA and elemental ratios allowed delimiting the end-members responsible for water quality variations at a catchment scale. The further application of MIX quantified the significant impact of AMD on the river quality; less than 10% of AMD relative contribution is enough to maintain acidic conditions during most of the year. The mixing model also provided information about the element mobility, distinguishing those elements with a quasi-conservative behavior (e.g., Cu, Zn, Al, Co or Ni) from those affected by mineral precipitation/dissolution (e.g., K, Si, Na, Sr, Ca, Fe, Pb, or As). Floods are the main driver of dissolved and, mainly particulate, contaminants in the catchment. Thus, the first rainfall events in November only accounted for 19% of the annual Meca flow but yielded between 26 and 43% of the net acidity and dissolved metal loads (mainly, Fe, As and Pb). Concerning particulate transport, around 332 tons of particulate Fe, 49 tons of Al, 0.79 tons of As and 0.37 tons of Pb were recorded during these first floods. The particulate As concentration can be up to 34 times higher than the dissolved one during floods and between 2 and 4 times higher for Fe, Pb and Cr. This integrated modeling approach could be a promising and useful tool to face future restoration plans in derelict mines worldwide. This approach would allow prioritizing remedial measures, achieving an environmental and cost-effective restoration of degraded areas.

Multi-scale finite element modeling of strain localization in geomaterials with strong discontinuity

NASA Astrophysics Data System (ADS)

Lai, Timothy Yu

2002-01-01

Geomaterials such as soils and rocks undergo strain localization during various loading conditions. Strain localization manifests itself in the form of a shear band, a narrow zone of intense straining. It is now generally recognized that these localized deformations lead to an accelerated softening response and influence the response of structures at or near failure. In order to accurately predict the behavior of geotechnical structures, the effects of strain localization must be included in any model developed. In this thesis, a multi-scale Finite Element (FE) model has been developed that captures the macro- and micro-field deformation patterns present during strain localization. The FE model uses a strong discontinuity approach where a jump in the displacement field is assumed. The onset of strain localization is detected using bifurcation theory that checks when the governing equations lose ellipticity. Two types of bifurcation, continuous and discontinuous are considered. Precise conditions for plane strain loading conditions are reported for each type of bifurcation. Post-localization behavior is governed by the traction relations on the band. Different plasticity models such as Mohr-Coulomb, Drucker-Prager and a Modified Mohr-Coulomb yield were implemented together with cohesion softening and cutoff for the post-localization behavior. The FE model is implemented into a FORTRAN code SPIN2D-LOC using enhanced constant strain triangular (CST) elements. The model is formulated using standard Galerkin finite element method, applicable to problems under undrained conditions and small deformation theory. A band-tracing algorithm is implemented to track the propagation of the shear band. To validate the model, several simulations are performed from simple compression test of soft rock to simulation of a full-scale geosynthetic reinforced soil wall model undergoing strain localization. Results from both standard and enhanced FE method are included for comparison. The resulting load-displacement curves show that the model can represent the softening behavior of geomaterials once strain localization is detected. The orientation of the shear band is found to depend on both the friction and dilation angle of the geomaterial. For most practical problems, slight mesh dependency can be expected but is associated with the standard FE interpolation rather than the strong discontinuity enhancements.

COMPUTERIZED TRAINING OF CRYOSURGERY – A SYSTEM APPROACH

PubMed Central

Keelan, Robert; Yamakawa, Soji; Shimada, Kenji; Rabin, Yoed

2014-01-01

The objective of the current study is to provide the foundation for a computerized training platform for cryosurgery. Consistent with clinical practice, the training process targets the correlation of the frozen region contour with the target region shape, using medical imaging and accepted criteria for clinical success. The current study focuses on system design considerations, including a bioheat transfer model, simulation techniques, optimal cryoprobe layout strategy, and a simulation core framework. Two fundamentally different approaches were considered for the development of a cryosurgery simulator, based on a finite-elements (FE) commercial code (ANSYS) and a proprietary finite-difference (FD) code. Results of this study demonstrate that the FE simulator is superior in terms of geometric modeling, while the FD simulator is superior in terms of runtime. Benchmarking results further indicate that the FD simulator is superior in terms of usage of memory resources, pre-processing, parallel processing, and post-processing. It is envisioned that future integration of a human-interface module and clinical data into the proposed computer framework will make computerized training of cryosurgery a practical reality. PMID:23995400

Latent hardening size effect in small-scale plasticity

NASA Astrophysics Data System (ADS)

Bardella, Lorenzo; Segurado, Javier; Panteghini, Andrea; Llorca, Javier

2013-07-01

We aim at understanding the multislip behaviour of metals subject to irreversible deformations at small-scales. By focusing on the simple shear of a constrained single-crystal strip, we show that discrete Dislocation Dynamics (DD) simulations predict a strong latent hardening size effect, with smaller being stronger in the range [1.5 µm, 6 µm] for the strip height. We attempt to represent the DD pseudo-experimental results by developing a flow theory of Strain Gradient Crystal Plasticity (SGCP), involving both energetic and dissipative higher-order terms and, as a main novelty, a strain gradient extension of the conventional latent hardening. In order to discuss the capability of the SGCP theory proposed, we implement it into a Finite Element (FE) code and set its material parameters on the basis of the DD results. The SGCP FE code is specifically developed for the boundary value problem under study so that we can implement a fully implicit (Backward Euler) consistent algorithm. Special emphasis is placed on the discussion of the role of the material length scales involved in the SGCP model, from both the mechanical and numerical points of view.

The origin and evolution of the odd-Z iron-peak elements Sc, V, Mn, and Co in the Milky Way stellar disk

NASA Astrophysics Data System (ADS)

Battistini, Chiara; Bensby, Thomas

2015-05-01

Context. Elements heavier than Li are produced in the interiors of stars. However, for many elements the exact production sites and the timescales on which they are dispersed into the interstellar medium are unknown. Having a clear picture on the origins of the elements is important for our ability to trace and understand the formation and chemical evolution of the Milky Way and its stellar populations. Aims: The aim of this study is to investigate the origin and evolution of Sc, V, Mn, and Co for a homogeneous and statistically significant sample of stars probing the different populations of the Milky Way, in particular the thin and thick disks. Methods: Using high-resolution spectra obtained with the MIKE, FEROS, SOFIN, FIES, UVES, and HARPS spectrographs, we determine Sc, V, Mn, and Co abundances for a large sample of F and G dwarfs in the solar neighborhood. The method is based on spectral synthesis and using one-dimensional, plane-parallel, local thermodynamic equilibrium (LTE) model stellar atmospheres calculated with the MARCS 2012 code. The non-LTE (NLTE) corrections from the literature were applied to Mn and Co. Results: We find that the abundance trends derived for Sc (594 stars), V (466 stars), and Co (567 stars) are very similar to what has been observed for the α-elements in the thin and thick disks. On the contrary, Mn (569 stars) is generally underabundant relative to the Sun (i.e., [ Mn/Fe ] < 0) for [ Fe/H ] < 0. In addition, for Mn, when NLTE corrections are applied, the trend changes and is almost flat over the entire metallicity range of the stars in our sample (-2 ≲ [ Fe/H ] ≲ + 0.4). The [Sc/Fe]-[Fe/H] abundance trends show a small separation between the thin and thick disks, while for V and Co they completely overlap. For Mn there is a small difference in [Mn/Fe], but only when NLTE corrections are used. Comparisons with Ti as a reference element show flat trends for all the elements except for Mn that show well separated [Mn/Ti]-[Ti/H] trends for the thin and thick disks. Conclusions: The elements Sc and V present trends compatible with production from type II supernovae (SNII) events. In addition, Sc clearly shows a metallicity dependence for [ Fe/H ] < -1. Instead, Mn is produced in SNII events for [ Fe/H ] ≲ -0.4 and then type Ia supernovae start to produce Mn. Finally, Co appears to be produced mainly in SNII with suggestion of enrichment from hypernovae at low metallicities. This paper includes data gathered with the 6.5 m Magellan Telescopes located at the Las Campanas Observatory, Chile; the Nordic Optical Telescope (NOT) on La Palma, Spain; the Very Large Telescope (VLT) at the European Southern Observatory (ESO) on Paranal, Chile (ESO Proposal ID 69.B-0277 and 72.B-0179); the ESO 1.5-m, 2.2-m. and 3.6-m telescopes on La Silla, Chile (ESO Proposal ID 65.L-0019, 67.B-0108, 76.B-0416, 82.B-0610); and data from UVES Paranal Observatory Project (ESO DDT Program ID 266.D-5655).Full versions of Tables 2 and 5 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/577/A9Appendices are available in electronic form at http://www.aanda.org

The Type Ic SN 2007gr: a census of the ejecta from late-time optical-infrared spectra

NASA Astrophysics Data System (ADS)

Mazzali, Paolo A.; Maurer, I.; Valenti, S.; Kotak, R.; Hunter, D.

2010-10-01

Nebular spectra of supernovae (SNe) offer an unimpeded view of the inner region of the ejecta, where most nucleosynthesis takes place. Optical spectra cover most, but not all, of the emitting elements and therefore offer only a partial view of the products of the explosion. Simultaneous optical-infrared spectra, on the other hand, contain emission lines of all important elements, from C and O through to the intermediate mass elements (IME) Mg, Si, S, Ca and to Fe and Ni. In particular, Si and S are best seen in the IR. The availability of IR data makes it possible to explore in greater detail the results of the explosion. SN2007gr is the first Type Ic SN for which such data are available. Modelling the spectra with a non-local thermodynamic equilibrium (NLTE) code reveals that the inner ejecta contain ~1Msolar of material within a velocity of ~4500kms-1. The same mass of 56Ni derived from the light-curve peak (0.076Msolar) was used to power the spectrum, yielding consistent results. Oxygen is the dominant element, contributing ~0.8Msolar. The C/O ratio is <0.2. IME account for ~0.1Msolar. This confirms that SN2007gr was the explosion of a low-mass CO core, probably the result of a star of main-sequence mass ~15Msolar. The ratios of the CaII lines, and those of FeII, are sensitive to the assumed degree of clumping. In particular, the optical lines of [FeII] become stronger, relative to the IR lines, for higher degrees of clumping.

Spectral fitting of SDSS passive galaxies with α-enhanced single stellar populations

NASA Astrophysics Data System (ADS)

Gomes, Jean Michel; Coelho, Paula

2012-08-01

The power of population synthesis as a mean to estimate the star-formation and chemical histories of galaxies has been well established in the last decade. The major developments were due to a huge avalanche of methods, codes and high-quality galaxy data sets, such as the 2dF, 6dF and SDSS surveys. Semi-empirical spectral synthesis allows for the decomposition of a galaxy spectrum in terms of linear combinations of base elements, i.e. Single Stellar Populations (SSPs) of different ages and metallicities, which are computed from evolutionary synthesis codes (BPASS, GALEV, GALAXEV, MILES, PÉGASE, etc. . .), containing distinct ingredients like: stellar library, evolutionary tracks, metallicities and Initial Mass Function. In general, they have solar-scaled relative abundances, but this is about to change with the unfolding of new α-enhanced SSP models (Coelho et al. 2007). However, passive galaxies have some spectral features corresponding to ``enhanced-ratios'' ([E/Fe]), like O, Ne, Si, S, Mg, Na, C and N over Fe that are not well modeled using solar-scaled SSPs (Trager et al. 2000), leading to residuals between observed and modeled spectra, which also correlate with the velocity dispersion (σ*) and stellar mass (M *): Massive galaxies exhibit a larger [E/Fe] discrepancy than less massive ones. This result can be interpreted as a signature of distinct previous star-formation efficiencies in passive galaxies, leading to distinctive ratios of type Ia and II SNe. We have applied the starlight spectral synthesis code (Cid Fernandes et al. 2005) to a sample of ~ 1000 passive galaxies from the SDSS DR7 with a S/N at the continuum >= 20 to investigate possible enhancements in the derived [E/Fe] ratios. Three sets of SSPs based on Coelho et al. (2007) theoretical models and Walcher et al. (2009) prescriptions were computed for [α/Fe]=0.0, [α/Fe]=0.2 and [α/Fe]=0.4. Our aim is to determine: (1) the quality of the fits, (2) the mean stellar age and metallicity distributions, and (3) the star-formation history of passive galaxies. Using [α/Fe]=0.0 SSPs, we have identified the strongest residuals in the CN (4142.125-4177.125 Å), Na D (5876.875-5909.375 Å) and Mg (5069.125-5196.625 Å) bands. On the other hand, [α/Fe]=0.2 and [α/Fe]=0.4 SSP models tend to reproduce better the Mg band, as compared to solar-scaled SSPs ([α/Fe]=0.0). The residuals are decreased by 1.77 Å ([α/Fe]=0.2) and 2.92 Å ([α/Fe]=0.4). However, as expected, these α-enhanced models lead to worse fits for the CN and Na D bands. These residuals may even reach up to 2.08 Å (CN) and 4.20 Å (Na D), using [α/Fe]=0.2 SSPs and 2.28 Å (CN) and 7.94 Å (Na D), using [α/Fe]=0.4 SSPs. In terms of mean stellar ages and metallicities, we obtain non-negligible biases in both quantities when we compare the solar-scaled SSPs with α-enhanced ones, which tend to have mean stellar ages by 0.12 dex ([α/Fe]=0.2) and 0.14 dex ([α/Fe]=0.4) higher and mean stellar metallicities by 0.1 dex ([α/Fe]=0.2) and 0.2 dex ([α/Fe]=0.4) lower.

Variation in trace element content of magnetite crystallized from a fractionating sulfide liquid, Sudbury, Canada: Implications for provenance discrimination

NASA Astrophysics Data System (ADS)

Dare, Sarah A. S.; Barnes, Sarah-Jane; Beaudoin, Georges

2012-07-01

Laser ablation ICP-MS analysis has been applied to many accessory minerals in order to understand better the process by which the rock formed and for provenance discrimination. We have determined trace element concentrations of Fe-oxides in massive sulfides that form Ni-Cu-PGE deposits at the base of the Sudbury Igneous Complex in Canada. The samples represent the crystallization products of fractionating sulfide liquids and consist of early-forming Fe-rich monosulfide solution (MSS) cumulates and residual Cu-rich intermediate solid solution (ISS). This study shows that Fe-oxide geochemistry is a sensitive petrogenetic indicator for the degree of fractionation of the sulfide liquid and provides an insight into the partitioning of elements between sulfide and Fe-oxide phases. In addition, it is useful in determining the provenance of detrital Fe-oxide. In a sulfide melt, all lithophile elements (Cr, Ti, V, Al, Mn, Sc, Nb, Ga, Ge, Ta, Hf, W and Zr) are compatible into Fe-oxide. The concentrations of these elements are highest in the early-forming Fe-oxide (titanomagnetite) which crystallized with Fe-rich MSS. Upon the continual crystallization of Fe-oxide from the sulfide liquid, the lithophile elements gradually decrease so that late-forming Fe-oxide (magnetite), which crystallized from the residual Cu-rich liquid, is depleted in these elements. This behavior is in contrast with Fe-oxides that crystallized from a fractionating silicate melt, whereby the concentration of incompatible elements, such as Ti, increases rather than decreases. The behavior of the chalcophile elements in magnetite is largely controlled by the crystallization of the sulfide minerals with only Ni, Co, Zn, Mo, Sn and Pb present above detection limit in magnetite. Nickel, Mo and Co are compatible in Fe-rich MSS and thus the co-crystallizing Fe-oxide is depleted in these elements. In contrast, magnetite that crystallized later from the fractionated liquid with Cu-rich ISS is enriched in Ni, Mo and Co because Fe-rich MSS is absent. The concentrations of Sn and Pb, which are incompatible with Fe-rich MSS, are highest in magnetite that formed from the fractionated Cu-rich liquid. At subsolidus temperatures, ilmenite exsolved from titanomagnetite whereas Al-spinel exsolved from the cores of some magnetite, locally redistributing the trace elements. However, during laser ablation ICP-MS analysis of these Fe-oxides both the magnetite and its exsolution products are ablated so that the analysis represents the original magmatic composition of the Fe-oxide that crystallized from the sulfide melt.

Variable magnetic field (VMF) effect on the heat transfer of a half-annulus cavity filled by Fe3O4-water nanofluid under constant heat flux

NASA Astrophysics Data System (ADS)

Hatami, M.; Zhou, J.; Geng, J.; Jing, D.

2018-04-01

In this paper, the effect of a variable magnetic field (VMF) on the natural convection heat transfer of Fe3O4-water nanofluid in a half-annulus cavity is studied by finite element method using FlexPDE commercial code. After deriving the governing equations and solving the problem by defined boundary conditions, the effects of three main parameters (Hartmann Number (Ha), nanoparticles volume fraction (φ) and Rayleigh number (Ra)) on the local and average Nusselt numbers of inner wall are investigated. As a main outcome, results confirm that in low Eckert numbers, increasing the Hartmann number make a decrease on the Nusselt number due to Lorentz force resulting from the presence of stronger magnetic field.

Hemodynamics of physiological blood flow in the aorta with nonlinear anisotropic heart valve

NASA Astrophysics Data System (ADS)

Sotiropoulos, Fotis; Gilmanov, Anvar; Stolarski, Henryk

2016-11-01

The hemodynamic blood flow in cardiovascular system is one of the most important factor, which causing several vascular diseases. We developed a new Curvilinear Immersed Boundary - Finite Element - Fluid Structure Interaction (CURVIB-FE-FSI) method to analyze hemodynamic of pulsatile blood flow in a real aorta with nonlinear anisotropic aortic valve at physiological conditions. Hyperelastic material model, which is more realistic for describing heart valve have been incorporated in the CURVIB-FE-FSI code to simulate interaction of aortic heart valve with pulsatile blood flow. Comparative studies of hemodynamics for linear and nonlinear models of heart valve show drastic differences in blood flow patterns and hence differences of stresses causing impact at leaflets and aortic wall. This work is supported by the Lillehei Heart Institute at the University of Minnesota.

Terminal oxidase diversity and function in "Metallosphaera yellowstonensis": gene expression and protein modeling suggest mechanisms of Fe(II) oxidation in the sulfolobales.

PubMed

Kozubal, M A; Dlakic, M; Macur, R E; Inskeep, W P

2011-03-01

"Metallosphaera yellowstonensis" is a thermoacidophilic archaeon isolated from Yellowstone National Park that is capable of autotrophic growth using Fe(II), elemental S, or pyrite as electron donors. Analysis of the draft genome sequence from M. yellowstonensis strain MK1 revealed seven different copies of heme copper oxidases (subunit I) in a total of five different terminal oxidase complexes, including doxBCEF, foxABCDEFGHIJ, soxABC, and the soxM supercomplex, as well as a novel hypothetical two-protein doxB-like polyferredoxin complex. Other genes found in M. yellowstonensis with possible roles in S and or Fe cycling include a thiosulfate oxidase (tqoAB), a sulfite oxidase (som), a cbsA cytochrome b(558/566), several small blue copper proteins, and a novel gene sequence coding for a putative multicopper oxidase (Mco). Results from gene expression studies, including reverse transcriptase (RT) quantitative PCR (qPCR) of cultures grown autotrophically on either Fe(II), pyrite, or elemental S showed that the fox gene cluster and mco are highly expressed under conditions where Fe(II) is an electron donor. Metagenome sequence and gene expression studies of Fe-oxide mats confirmed the importance of fox genes (e.g., foxA and foxC) and mco under Fe(II)-oxidizing conditions. Protein modeling of FoxC suggests a novel lysine-lysine or lysine-arginine heme B binding domain, indicating that it is likely the cytochrome component of a heterodimer complex with foxG as a ferredoxin subunit. Analysis of mco shows that it encodes a novel multicopper blue protein with two plastocyanin type I copper domains that may play a role in the transfer of electrons within the Fox protein complex. An understanding of metabolic pathways involved in aerobic iron and sulfur oxidation in Sulfolobales has broad implications for understanding the evolution and niche diversification of these thermophiles as well as practical applications in fields such as bioleaching of trace metals from pyritic ores.

Wheel-Sleeper Impact Model in Rail Vehicles Analysis

NASA Astrophysics Data System (ADS)

Brabie, Dan

The current paper establishes the necessary prerequisites for studying post-derailment dynamic behavior of high-speed rail vehicles by means of multi-body system (MBS) software. A finite-element (FE) model of one rail vehicle wheel impacting a limited concrete sleeper volume is built in LS-DYNA. A novel simulation scheme is employed for obtaining the necessary wheel-sleeper impact data, transferred to the MBS code as pre-defined look-up tables of the wheel's impulse variation during impact. The FE model is tentatively validated successfully by comparing the indentation marks with one photograph from an authentic derailment for a continuous impact sequence over three subsequent sleepers. A post-derailment module is developed and implemented in the MBS simulation tool GENSYS, which detects the wheel contact with sleepers and applies valid longitudinal, lateral and vertical force resultants based on the existing impact conditions. The accuracy of the MBS code in terms of the wheels three-dimensional trajectory over 24 consecutive sleepers is successfully compared with its FE counterpart for an arbitrary impact scenario. An axle mounted brake disc is tested as an alternative substitute guidance mechanism after flange climbing derailments at 100 and 200 km/h on the Swedish high-speed tilting train X 2000. Certain combinations of brake disc geometrical parameters manage to stop the lateral deviation of the wheelsets in circular curve sections at high lateral track plane acceleration.

Thermodynamic stability of stoichiometric LaFeO3 and BiFeO3: a hybrid DFT study.

PubMed

Heifets, Eugene; Kotomin, Eugene A; Bagaturyants, Alexander A; Maier, Joachim

2017-02-01

BiFeO 3 perovskite attracts great attention due to its multiferroic properties and potential use as a parent material for Bi 1-x Sr x FeO 3-δ and Bi 1-x Sr x Fe 1-y Co y O 3-δ solid solutions in intermediate temperature cathodes of oxide fuel cells. Another iron-based LaFeO 3 perovskite is the end member for well-known solid solutions (La 1-x Sr x Fe 1-y Co y O 3-δ ) used for oxide fuel cells and other electrochemical devices. In this study an ab initio hybrid functional approach was used for the study of the thermodynamic stability of both LaFeO 3 and BiFeO 3 with respect to decompositions to binary oxides and to elements, as a function of temperature and oxygen pressure. The localized (LCAO) basis sets describing the crystalline electron wave functions were carefully re-optimized within the CRYSTAL09 computer code. The results obtained by considering Fe as an all-electron atom and within the effective core potential technique are compared in detail. Based on our calculations, the phase diagrams were constructed allowing us to predict the stability region of stoichiometric materials in terms of atomic chemical potentials. This permits determining the environmental conditions for the existence of stable BiFeO 3 and LaFeO 3 . These conditions were presented as contour maps of oxygen atoms' chemical potential as a function of temperature and partial pressure of oxygen gas. A similar analysis was also performed using the experimental Gibbs energies of formation. The obtained phase diagrams and contour maps are compared with the calculated ones.

Theoretical modeling of laser-induced plasmas using the ATOMIC code

NASA Astrophysics Data System (ADS)

Colgan, James; Johns, Heather; Kilcrease, David; Judge, Elizabeth; Barefield, James, II; Clegg, Samuel; Hartig, Kyle

2014-10-01

We report on efforts to model the emission spectra generated from laser-induced breakdown spectroscopy (LIBS). LIBS is a popular and powerful method of quickly and accurately characterizing unknown samples in a remote manner. In particular, LIBS is utilized by the ChemCam instrument on the Mars Science Laboratory. We model the LIBS plasma using the Los Alamos suite of atomic physics codes. Since LIBS plasmas generally have temperatures of somewhere between 3000 K and 12000 K, the emission spectra typically result from the neutral and singly ionized stages of the target atoms. We use the Los Alamos atomic structure and collision codes to generate sets of atomic data and use the plasma kinetics code ATOMIC to perform LTE or non-LTE calculations that generate level populations and an emission spectrum for the element of interest. In this presentation we compare the emission spectrum from ATOMIC with an Fe LIBS laboratory-generated plasma as well as spectra from the ChemCam instrument. We also discuss various physics aspects of the modeling of LIBS plasmas that are necessary for accurate characterization of the plasma, such as multi-element target composition effects, radiation transport effects, and accurate line shape treatments. The Los Alamos National Laboratory is operated by Los Alamos National Security, LLC for the National Nuclear Security Administration of the U.S. Department of Energy under Contract No. DE-AC5206NA25396.

Determining nucleosynthesis yields in supernovae with spectral modelling

NASA Astrophysics Data System (ADS)

Jerkstrand, Anders

2018-04-01

The methodology to estimate element masses in supernova ejecta from nebular spectroscopy is discussed. Results using the SUMO spectral synthesis code are reviewed with regard to two key elements; oxygen (a hydrostatic burning ash) and nickel (an explosive burning ash). The typical oxygen mass in both Type IIP and IIb supernovae is found to be ˜0.5 M⊙, and points to progenitor stars in the 8 - 17 M⊙ range. For nickel, a new diagnostic method has been developed that shows Ni/Fe production close to solar in most cases, but sometimes larger by a factor of a few. It is shown that the larger values require the burning of silicon shell layers in the progenitor, a unique constraint on explosion theory.

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

Van Der Marck, S. C.

Three nuclear data libraries have been tested extensively using criticality safety benchmark calculations. The three libraries are the new release of the US library ENDF/B-VII.1 (2011), the new release of the Japanese library JENDL-4.0 (2011), and the OECD/NEA library JEFF-3.1 (2006). All calculations were performed with the continuous-energy Monte Carlo code MCNP (version 4C3, as well as version 6-beta1). Around 2000 benchmark cases from the International Handbook of Criticality Safety Benchmark Experiments (ICSBEP) were used. The results were analyzed per ICSBEP category, and per element. Overall, the three libraries show similar performance on most criticality safety benchmarks. The largest differencesmore » are probably caused by elements such as Be, C, Fe, Zr, W. (authors)« less

FAMA: Fast Automatic MOOG Analysis

NASA Astrophysics Data System (ADS)

Magrini, Laura; Randich, Sofia; Friel, Eileen; Spina, Lorenzo; Jacobson, Heather; Cantat-Gaudin, Tristan; Donati, Paolo; Baglioni, Roberto; Maiorca, Enrico; Bragaglia, Angela; Sordo, Rosanna; Vallenari, Antonella

2014-02-01

FAMA (Fast Automatic MOOG Analysis), written in Perl, computes the atmospheric parameters and abundances of a large number of stars using measurements of equivalent widths (EWs) automatically and independently of any subjective approach. Based on the widely-used MOOG code, it simultaneously searches for three equilibria, excitation equilibrium, ionization balance, and the relationship between logn(FeI) and the reduced EWs. FAMA also evaluates the statistical errors on individual element abundances and errors due to the uncertainties in the stellar parameters. Convergence criteria are not fixed "a priori" but instead are based on the quality of the spectra.

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

Côté, Benoit; Belczynski, Krzysztof; Fryer, Chris L.

The role of compact binary mergers as the main production site of r-process elements is investigated by combining stellar abundances of Eu observed in the Milky Way, galactic chemical evolution (GCE) simulations, and binary population synthesis models, and gravitational wave measurements from Advanced LIGO. We compiled and reviewed seven recent GCE studies to extract the frequency of neutron star–neutron star (NS–NS) mergers that is needed in order to reproduce the observed [Eu/Fe] versus [Fe/H] relationship. We used our simple chemical evolution code to explore the impact of different analytical delay-time distribution functions for NS–NS mergers. We then combined our metallicity-dependent population synthesis models with our chemical evolution code to bring their predictions, for both NS–NS mergers and black hole–neutron star mergers, into a GCE context. Finally, we convolved our results with the cosmic star formation history to provide a direct comparison with current and upcoming Advanced LIGO measurements. When assuming that NS–NS mergers are the exclusive r-process sites, and that the ejected r-process mass per merger event is 0.01 Mmore » $${}_{\\odot }$$, the number of NS–NS mergers needed in GCE studies is about 10 times larger than what is predicted by standard population synthesis models. Here, these two distinct fields can only be consistent with each other when assuming optimistic rates, massive NS–NS merger ejecta, and low Fe yields for massive stars. For now, population synthesis models and GCE simulations are in agreement with the current upper limit (O1) established by Advanced LIGO during their first run of observations. Upcoming measurements will provide an important constraint on the actual local NS–NS merger rate, will provide valuable insights on the plausibility of the GCE requirement, and will help to define whether or not compact binary mergers can be the dominant source of r-process elements in the universe.« less

Advanced LIGO constraints on neutron star mergers and r-process sites

DOE PAGES

Côté, Benoit; Belczynski, Krzysztof; Fryer, Chris L.; ...

2017-02-20

The role of compact binary mergers as the main production site of r-process elements is investigated by combining stellar abundances of Eu observed in the Milky Way, galactic chemical evolution (GCE) simulations, and binary population synthesis models, and gravitational wave measurements from Advanced LIGO. We compiled and reviewed seven recent GCE studies to extract the frequency of neutron star–neutron star (NS–NS) mergers that is needed in order to reproduce the observed [Eu/Fe] versus [Fe/H] relationship. We used our simple chemical evolution code to explore the impact of different analytical delay-time distribution functions for NS–NS mergers. We then combined our metallicity-dependent population synthesis models with our chemical evolution code to bring their predictions, for both NS–NS mergers and black hole–neutron star mergers, into a GCE context. Finally, we convolved our results with the cosmic star formation history to provide a direct comparison with current and upcoming Advanced LIGO measurements. When assuming that NS–NS mergers are the exclusive r-process sites, and that the ejected r-process mass per merger event is 0.01 Mmore » $${}_{\\odot }$$, the number of NS–NS mergers needed in GCE studies is about 10 times larger than what is predicted by standard population synthesis models. Here, these two distinct fields can only be consistent with each other when assuming optimistic rates, massive NS–NS merger ejecta, and low Fe yields for massive stars. For now, population synthesis models and GCE simulations are in agreement with the current upper limit (O1) established by Advanced LIGO during their first run of observations. Upcoming measurements will provide an important constraint on the actual local NS–NS merger rate, will provide valuable insights on the plausibility of the GCE requirement, and will help to define whether or not compact binary mergers can be the dominant source of r-process elements in the universe.« less

A Validated Open-Source Multisolver Fourth-Generation Composite Femur Model.

PubMed

MacLeod, Alisdair R; Rose, Hannah; Gill, Harinderjit S

2016-12-01

Synthetic biomechanical test specimens are frequently used for preclinical evaluation of implant performance, often in combination with numerical modeling, such as finite-element (FE) analysis. Commercial and freely available FE packages are widely used with three FE packages in particular gaining popularity: abaqus (Dassault Systèmes, Johnston, RI), ansys (ANSYS, Inc., Canonsburg, PA), and febio (University of Utah, Salt Lake City, UT). To the best of our knowledge, no study has yet made a comparison of these three commonly used solvers. Additionally, despite the femur being the most extensively studied bone in the body, no freely available validated model exists. The primary aim of the study was primarily to conduct a comparison of mesh convergence and strain prediction between the three solvers (abaqus, ansys, and febio) and to provide validated open-source models of a fourth-generation composite femur for use with all the three FE packages. Second, we evaluated the geometric variability around the femoral neck region of the composite femurs. Experimental testing was conducted using fourth-generation Sawbones® composite femurs instrumented with strain gauges at four locations. A generic FE model and four specimen-specific FE models were created from CT scans. The study found that the three solvers produced excellent agreement, with strain predictions being within an average of 3.0% for all the solvers (r2 > 0.99) and 1.4% for the two commercial codes. The average of the root mean squared error against the experimental results was 134.5% (r2 = 0.29) for the generic model and 13.8% (r2 = 0.96) for the specimen-specific models. It was found that composite femurs had variations in cortical thickness around the neck of the femur of up to 48.4%. For the first time, an experimentally validated, finite-element model of the femur is presented for use in three solvers. This model is freely available online along with all the supporting validation data.

Finite element simulation of adaptive aerospace structures with SMA actuators

NASA Astrophysics Data System (ADS)

Frautschi, Jason; Seelecke, Stefan

2003-07-01

The particular demands of aerospace engineering have spawned many of the developments in the field of adaptive structures. Shape memory alloys are particularly attractive as actuators in these types of structures due to their large strains, high specific work output and potential for structural integration. However, the requisite extensive physical testing has slowed development of potential applications and highlighted the need for a simulation tool for feasibility studies. In this paper we present an implementation of an extended version of the M'ller-Achenbach SMA model into a commercial finite element code suitable for such studies. Interaction between the SMA model and the solution algorithm for the global FE equations is thoroughly investigated with respect to the effect of tolerances and time step size on convergence, computational cost and accuracy. Finally, a simulation of a SMA-actuated flexible trailing edge of an aircraft wing modeled with beam elements is presented.

The Abundances of the Fe Group Elements in Early B Stars in the Magellanic Clouds and Bridge

NASA Astrophysics Data System (ADS)

Peters, Geraldine J.; Adelman, Saul J.

2016-01-01

The abundances of three Fe Group elements (V, Cr, and Fe) in 9 early main-sequence band B stars in the LMC, 7 in the SMC , and two in the Magellanic Bridge have been determined from archival FUSE observations and the Hubeny/Lanz NLTE programs TLUSTY/SYNSPEC. Lines from the Fe group elements, except for a few weak multiplets of Fe III, are not observable in the optical spectral region. The best set of lines in the FUSE spectral region are Fe III (UV1), V III 1150 Å, and Cr III 1137 Å. The abundances of these elements in early B stars are a marker for recent SNe Ia activity, as a single exploding white dwarf can deliver 0.5 solar masses of Ni-56 that decays into Fe to the ISM. The Fe group abundances in an older population of stars primarily reflect SNe II activity, in which a single explosion delivers only 0.07 solar masses of Ni-56 to the ISM (the rest remains trapped in the neutron star). The abundances of the Fe group elements in early B stars not only track SNe Ia activity but are also important for computing evolutionary tracks for massive stars. In general, the Fe abundance relative to the sun's value is comparable to the mean abundances for the lighter elements in the Clouds/Bridge but the values of [V,Cr/Fe]sun are smaller. This presentation will discuss the spatial distribution of the Fe Group elements in the Magellanic Clouds, and compare it with our galaxy in which the abundance of Fe declines with radial distance from the center. Support from NASA grants NAG5-13212, NNX10AD66G, STScI HST-GO-13346.22, and USC's Women in Science and Engineering (WiSE) program is greatly appreciated.

FAMA: An automatic code for stellar parameter and abundance determination

NASA Astrophysics Data System (ADS)

Magrini, Laura; Randich, Sofia; Friel, Eileen; Spina, Lorenzo; Jacobson, Heather; Cantat-Gaudin, Tristan; Donati, Paolo; Baglioni, Roberto; Maiorca, Enrico; Bragaglia, Angela; Sordo, Rosanna; Vallenari, Antonella

2013-10-01

Context. The large amount of spectra obtained during the epoch of extensive spectroscopic surveys of Galactic stars needs the development of automatic procedures to derive their atmospheric parameters and individual element abundances. Aims: Starting from the widely-used code MOOG by C. Sneden, we have developed a new procedure to determine atmospheric parameters and abundances in a fully automatic way. The code FAMA (Fast Automatic MOOG Analysis) is presented describing its approach to derive atmospheric stellar parameters and element abundances. The code, freely distributed, is written in Perl and can be used on different platforms. Methods: The aim of FAMA is to render the computation of the atmospheric parameters and abundances of a large number of stars using measurements of equivalent widths (EWs) as automatic and as independent of any subjective approach as possible. It is based on the simultaneous search for three equilibria: excitation equilibrium, ionization balance, and the relationship between log n(Fe i) and the reduced EWs. FAMA also evaluates the statistical errors on individual element abundances and errors due to the uncertainties in the stellar parameters. The convergence criteria are not fixed "a priori" but are based on the quality of the spectra. Results: In this paper we present tests performed on the solar spectrum EWs that assess the method's dependency on the initial parameters and we analyze a sample of stars observed in Galactic open and globular clusters. The current version of FAMA is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/558/A38

PWSCC Assessment by Using Extended Finite Element Method

NASA Astrophysics Data System (ADS)

Lee, Sung-Jun; Lee, Sang-Hwan; Chang, Yoon-Suk

2015-12-01

The head penetration nozzle of control rod driving mechanism (CRDM) is known to be susceptible to primary water stress corrosion cracking (PWSCC) due to the welding-induced residual stress. Especially, the J-groove dissimilar metal weld regions have received many attentions in the previous studies. However, even though several advanced techniques such as weight function and finite element alternating methods have been introduced to predict the occurrence of PWSCC, there are still difficulties in respect of applicability and efficiency. In this study, the extended finite element method (XFEM), which allows convenient crack element modeling by enriching degree of freedom (DOF) with special displacement function, was employed to evaluate structural integrity of the CRDM head penetration nozzle. The resulting stress intensity factors of surface cracks were verified for the reliability of proposed method through the comparison with those suggested in the American Society of Mechanical Engineering (ASME) code. The detailed results from the FE analyses are fully discussed in the manuscript.

Characteristics and anticorrosion performance of Fe-doped TiO2 films by liquid phase deposition method

NASA Astrophysics Data System (ADS)

Liu, Yu; Xu, Chao; Feng, ZuDe

2014-09-01

Fe-doped TiO2 thin films were fabricated by liquid phase deposition (LPD) method, using Fe(III) nitrate as both Fe element source and fluoride scavenger instead of commonly-used boric acid (H3BO3). Scanning electron microscopy (SEM), X-ray diffraction (XRD), and UV-vis spectrum were employed to examine the effects of Fe element on morphology, structure and optical characteristics of TiO2 films. The as-prepared films were served as photoanode applied to photogenerated cathodic protection of SUS304 stainless steel (304SS). It was observed that the photoelectrochemical properties of the as-prepared films were enhanced with the addition of Fe element compared to the undoped TiO2 film. The highest photoactivity was achieved for Ti13Fe (Fe/Ti = 3 molar ratio) film prepared in precursor bath containing 0.02 M TiF4 + 0.06 M Fe(NO3)3 under white-light illumination. The effective anticorrosion behaviors can be attributed to the Fe element incorporation which decreases the probability of photogenerated charge-carrier recombination and extends the light response range of Fe-doped TiO2 films appeared to visible-light region.

Fine-structure excitation of Fe II and Fe III due to collisions with electrons

NASA Astrophysics Data System (ADS)

Wan, Yier; Qi, Yueying; Favreau, Connor; Loch, Stuart; Stancil, P.; Ballance, Connor; McLaughlin, Brendan

2018-06-01

Atomic data of iron peak elements are of great importance in astronomical observations. Among all the ionization stages of iron, Fe II and Fe III are of particular importance because of the high cosmic abundance, relatively low ionization potential and complex open d-shell atomic structure. Fe II and Fe III emission are observed from nearly all classes of astronomical objects over a wide spectral range from the infrared to the ultraviolet. To meaningfully interpret these spectra, astronomers have to employ highly complex modeling codes with reliable collision data to simulate the astrophysical observations. The major aim of this work is to provide reliable atomic data for diagnostics. We present new collision strengths and effective collisions for electron impact excitation of Fe II and Fe III for the forbidden transitions among the fine-structure levels of the ground terms. A very fine energy mesh is used for the collision strengths and the effective collision strengths are calculated over a wide range of electron temperatures of astrophysical importance (10-2000 K). The configuration interaction state wave functions are generated with a scaled Thomas-Fermi-Dirac-Amaldi (TFDA) potential, while the R-matrix plus intermediate coupling frame transformation (ICFT), Breit-Pauli R-matrix and Dirac R-matrix packages are used to obtain collision strengths. Influences of the different methods and configuration expansions on the collisional data are discussed. Comparison is made with earlier theoretical work and differences are found to occur at the low temperatures considered here.This work was funded by NASA grant NNX15AE47G.

Minimum depth of soil cover above long-span soil-steel railway bridges

NASA Astrophysics Data System (ADS)

Esmaeili, Morteza; Zakeri, Jabbar Ali; Abdulrazagh, Parisa Haji

2013-12-01

Recently, soil-steel bridges have become more commonly used as railway-highway crossings because of their economical advantages and short construction period compared with traditional bridges. The currently developed formula for determining the minimum depth of covers by existing codes is typically based on vehicle loads and non-stiffened panels and takes into consideration the geometrical shape of the metal structure to avoid the failure of soil cover above a soil-steel bridge. The effects of spans larger than 8 m or more stiffened panels due to railway loads that maintain a safe railway track have not been accounted for in the minimum cover formulas and are the subject of this paper. For this study, two-dimensional finite element (FE) analyses of four low-profile arches and four box culverts with spans larger than 8 m were performed to develop new patterns for the minimum depth of soil cover by considering the serviceability criterion of the railway track. Using the least-squares method, new formulas were then developed for low-profile arches and box culverts and were compared with Canadian Highway Bridge Design Code formulas. Finally, a series of three-dimensional (3D) finite element FE analyses were carried out to control the out-of-plane buckling in the steel plates due to the 3D pattern of train loads. The results show that the out-of-plane bending does not control the buckling behavior of the steel plates, so the proposed equations for minimum depth of cover can be appropriately used for practical purposes.

Spatially invariant coding of numerical information in functionally defined subregions of human parietal cortex.

PubMed

Eger, E; Pinel, P; Dehaene, S; Kleinschmidt, A

2015-05-01

Macaque electrophysiology has revealed neurons responsive to number in lateral (LIP) and ventral (VIP) intraparietal areas. Recently, fMRI pattern recognition revealed information discriminative of individual numbers in human parietal cortex but without precisely localizing the relevant sites or testing for subregions with different response profiles. Here, we defined the human functional equivalents of LIP (feLIP) and VIP (feVIP) using neurophysiologically motivated localizers. We applied multivariate pattern recognition to investigate whether both regions represent numerical information and whether number codes are position specific or invariant. In a delayed number comparison paradigm with laterally presented numerosities, parietal cortex discriminated between numerosities better than early visual cortex, and discrimination generalized across hemifields in parietal, but not early visual cortex. Activation patterns in the 2 parietal regions of interest did not differ in the coding of position-specific or position-independent number information, but in the expression of a numerical distance effect which was more pronounced in feLIP. Thus, the representation of number in parietal cortex is at least partially position invariant. Both feLIP and feVIP contain information about individual numerosities in humans, but feLIP hosts a coarser representation of numerosity than feVIP, compatible with either broader tuning or a summation code. © The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

EIT image reconstruction based on a hybrid FE-EFG forward method and the complete-electrode model.

PubMed

Hadinia, M; Jafari, R; Soleimani, M

2016-06-01

This paper presents the application of the hybrid finite element-element free Galerkin (FE-EFG) method for the forward and inverse problems of electrical impedance tomography (EIT). The proposed method is based on the complete electrode model. Finite element (FE) and element-free Galerkin (EFG) methods are accurate numerical techniques. However, the FE technique has meshing task problems and the EFG method is computationally expensive. In this paper, the hybrid FE-EFG method is applied to take both advantages of FE and EFG methods, the complete electrode model of the forward problem is solved, and an iterative regularized Gauss-Newton method is adopted to solve the inverse problem. The proposed method is applied to compute Jacobian in the inverse problem. Utilizing 2D circular homogenous models, the numerical results are validated with analytical and experimental results and the performance of the hybrid FE-EFG method compared with the FE method is illustrated. Results of image reconstruction are presented for a human chest experimental phantom.

Fractionation of trace elements in agricultural soils using ultrasound assisted sequential extraction prior to inductively coupled plasma mass spectrometric determination.

PubMed

Matong, Joseph M; Nyaba, Luthando; Nomngongo, Philiswa N

2016-07-01

The main objectives of this study were to determine the concentration of fourteen trace elements and to investigate their distribution as well as a contamination levels in selected agricultural soils. An ultrasonic assisted sequential extraction procedure derived from three-step BCR method was used for fractionation of trace elements. The total concentration of trace elements in soil samples was obtained by total digestion method in soil samples with aqua regia. The results of the extractable fractions revealed that most of the target trace elements can be transferred to the human being through the food chain, thus leading to serious human health. Enrichment factor (EF), geo-accumulation index (Igeo), contamination factor (CF), risk assessment code (RAC) and individual contamination factors (ICF) were used to assess the environmental impacts of trace metals in soil samples. The EF revealed that Cd was enriched by 3.1-7.2 (except in Soil 1). The Igeo results showed that the soils in the study area was moderately contaminated with Fe, and heavily to extremely polluted with Cd. The soil samples from the unplanted field was found to have highest contamination factor for Cd and lowest for Pb. Soil 3 showed a high risk for Tl and Cd with RAC values of greater than or equal to 50%. In addition, Fe, Ni, Cu, V, As, Mo (except Soil 2), Sb and Pb posed low environmental risk. The modified BCR sequential extraction method provided more information about mobility and environmental implication of studied trace elements in the study area. Copyright © 2016 Elsevier Ltd. All rights reserved.

Implementation and validation of the extended Hill-type muscle model with robust routing capabilities in LS-DYNA for active human body models.

PubMed

Kleinbach, Christian; Martynenko, Oleksandr; Promies, Janik; Haeufle, Daniel F B; Fehr, Jörg; Schmitt, Syn

2017-09-02

In the state of the art finite element AHBMs for car crash analysis in the LS-DYNA software material named *MAT_MUSCLE (*MAT_156) is used for active muscles modeling. It has three elements in parallel configuration, which has several major drawbacks: restraint approximation of the physical reality, complicated parameterization and absence of the integrated activation dynamics. This study presents implementation of the extended four element Hill-type muscle model with serial damping and eccentric force-velocity relation including [Formula: see text] dependent activation dynamics and internal method for physiological muscle routing. Proposed model was implemented into the general-purpose finite element (FE) simulation software LSDYNA as a user material for truss elements. This material model is verified and validated with three different sets of mammalian experimental data, taken from the literature. It is compared to the *MAT_MUSCLE (*MAT_156) Hill-type muscle model already existing in LS-DYNA, which is currently used in finite element human body models (HBMs). An application example with an arm model extracted from the FE ViVA OpenHBM is given, taking into account physiological muscle paths. The simulation results show better material model accuracy, calculation robustness and improved muscle routing capability compared to *MAT_156. The FORTRAN source code for the user material subroutine dyn21.f and the muscle parameters for all simulations, conducted in the study, are given at https://zenodo.org/record/826209 under an open source license. This enables a quick application of the proposed material model in LS-DYNA, especially in active human body models (AHBMs) for applications in automotive safety.

HPC Institutional Computing Project: W15_lesreactiveflow KIVA-hpFE Development: A Robust and Accurate Engine Modeling Software

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

Carrington, David Bradley; Waters, Jiajia

KIVA-hpFE is a high performance computer software for solving the physics of multi-species and multiphase turbulent reactive flow in complex geometries having immersed moving parts. The code is written in Fortran 90/95 and can be used on any computer platform with any popular complier. The code is in two versions, a serial version and a parallel version utilizing MPICH2 type Message Passing Interface (MPI or Intel MPI) for solving distributed domains. The parallel version is at least 30x faster than the serial version and much faster than our previous generation of parallel engine modeling software, by many factors. The 5thmore » generation algorithm construction is a Galerkin type Finite Element Method (FEM) solving conservative momentum, species, and energy transport equations along with two-equation turbulent model k-ω Reynolds Averaged Navier-Stokes (RANS) model and a Vreman type dynamic Large Eddy Simulation (LES) method. The LES method is capable modeling transitional flow from laminar to fully turbulent; therefore, this LES method does not require special hybrid or blending to walls. The FEM projection method also uses a Petrov-Galerkin (P-G) stabilization along with pressure stabilization. We employ hierarchical basis sets, constructed on the fly with enrichment in areas associated with relatively larger error as determined by error estimation methods. In addition, when not using the hp-adaptive module, the code employs Lagrangian basis or shape functions. The shape functions are constructed for hexahedral, prismatic and tetrahedral elements. The software is designed to solve many types of reactive flow problems, from burners to internal combustion engines and turbines. In addition, the formulation allows for direct integration of solid bodies (conjugate heat transfer), as in heat transfer through housings, parts, cylinders. It can also easily be extended to stress modeling of solids, used in fluid structure interactions problems, solidification, porous media modeling and magneto hydrodynamics.« less

Effects of dietary zinc, iron, and copper in layer feed on distribution of these elements in eggs, liver, excreta, soil, and herbage.

PubMed

Skrivan, M; Skrivanová, V; Marounek, M

2005-10-01

An experiment was conducted to evaluate the effect of dietary content and combinations of Zn, Fe, and Cu on deposition of these elements in egg components, liver, and excreta. Excreta were applied as a manure to a lawn, and 3 mo later soil and herbage samples were taken and analyzed. The experiment comprised 144 hens in 8 groups. The basal diet contained Zn, Fe, and Cu at 63.4, 92.8, and 9.0 mg/kg, respectively. It was supplemented with 1, 2, or 3 trace elements (inorganic forms) at 80 mg of Zn/kg, 120 mg of Fe/kg, and 25 mg of Cu/kg. Recovery of Zn, Fe, and Cu in eggs of hens fed the basal diet was 10.7, 9.8, and 4.4% of the alimentary intake, respectively. A Zn-Cu antagonism was observed; deposition of Zn in the yolk was significantly decreased by Cu addition and vice versa (P < 0.01). Supplementation of the basal diet with Fe increased Fe concentration in egg yolk and white by 6.3 and 2.2%, respectively. The combination of Fe with Zn and Cu, however, increased Fe concentration in the yolk and white by 36.7 and 34.9%, respectively (P < 0.01). The enrichment of eggs with the other elements was marginal (Cu) or absent (Zn). Effects of Zn, Fe, and Cu of the basal diet on liver concentrations of these elements were relatively small, and no antagonism between Zn and Cu was apparent. Supplementation of the basal diet with the combination of Zn and Fe, however, significantly decreased hepatic concentration of Cu. On the other hand, Cu supplementation significantly increased Fe concentration in livers of hens fed the Fe-supplemented diet (P < 0.01). Concentrations of Zn, Fe, and Cu in excreta were related to their dietary content. High concentrations of Zn, Fe, and Cu in excreta corresponded with limited deposition of the 3 elements in eggs and liver. Concentrations of Zn, Fe, and Cu in herbage correlated significantly with the supply of these elements by hen excreta into soil. The Zn supplied by hen excreta was more stable than Fe and Cu; thus Zn could accumulate in the soil.

Controls on Fe(II)-Activated Trace Element Release from Goethite and Hematite

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

Frierdich, Andrew J.; Catalano, Jeffrey G.

2012-03-26

Electron transfer and atom exchange (ETAE) between aqueous Fe(II) and Fe(III) oxides induces surface growth and dissolution that affects trace element fate and transport. We have recently demonstrated Ni(II) cycling through goethite and hematite (adsorbed Ni incorporates into the mineral structure and preincorporated Ni releases to solution) during Fe(II)-Fe(III) ETAE. However, the chemical parameters affecting net trace element release remain unknown. Here, we examine the chemical controls on Ni(II) and Zn(II) release from Ni- and Zn-substituted goethite and hematite during reaction with Fe(II). Release follows a rate law consistent with surface reaction limited mineral dissolution and suggests that release occursmore » near sites of Fe(III) reductive dissolution during Fe(II)-Fe(III) ETAE. Metal substituent type affects reactivity; Zn release is more pronounced from hematite than goethite, whereas the opposite trend occurs for Ni. Buildup of Ni or Zn in solution inhibits further release but this resumes upon fluid exchange, suggesting that sustained release is possible under flow conditions. Mineral and aqueous Fe(II) concentrations as well as pH strongly affect sorbed Fe(II) concentrations, which directly control the reaction rates and final metal concentrations. Our results demonstrate that structurally incorporated trace elements are mobilized from iron oxides into fluids without abiotic or microbial net iron reduction. Such release may affect micronutrient availability, contaminant transport, and the distribution of redox-inactive trace elements in natural and engineered systems.« less

Chalcophile element partitioning in highly oxidised and highly reduced bodies.

NASA Astrophysics Data System (ADS)

Kiseeva, K.; Wood, B. J.

2015-12-01

In our recent studies [1-3] we showed that partitioning of many chalcophile elements could be described by a simple relationship as a function of the FeO content of the silicate liquid. LogDi ~= A-0.5nlog[FeO] where A is a constant, n is the constant related to the valency of element i and [FeO] is the concentration of FeO in the silicate melt. For many chalcophile and moderately chalcophile elements (e.g., Zn, Cr, Pb, Sb, In), the fitted slope n depends only on the valency of the element. More lithophile elements (e.g., Ti, Nb, Ce, Ga) exhibit concave upwards behavior on a plot of logD versus log[FeO] due to their strong interaction with oxygen in sulphide, which increases with the increasing FeO content of the silicate liquid. Strongly chalcophile elements, like Cu, Ag and Ni have the opposite trend (concave downwards) and their D decreases both at high (> 10-12wt %) and very low (< 1wt%) FeO contents of the silicate melt. These changes correlate with increasing S content of the silicate melt (up to 11 wt%) as the FeO content of the silicate melt declines to ~0.3wt%. An experiment at 1.5 GPa/1420oC having 4 wt% S and 0.28 wt% FeO in the silicate melt has DCu (sulf/sil) ~ 84, which is about 6 times lower than the DCu(sulf/sil) at identical p-T conditions but at 8 wt% FeO in the silicate melt. Our new experimental data on Re partitioning between sulphide and silicate melt in the CMAS+FeO system show that Re behaves similarly to the highly chalcophile elements and exhibits concave downwards behaviour on the LogD/LogFeO diagram. With the highest DRe (sulf/sil) at around 1.5-2.0x104 at 1.5-6.0 wt% FeO in the silicate melt, DRe (sulf/sil) declines to the values of 50-150 at ~0.5 wt% and > ~15 wt% FeO in the silicate melt, respectively. This means that at highly reducing conditions Re is similarly or less chalcophile than some of the highly lithophile elements, like Ta (D ≈ 9), Nb (D ≈ 600), Ti (D ≈ 6) [3]. The results mean that in oxidised bodies like Mars and reduced bodies like Mercury, most "lithophile" elements partition more strongly into sulphide than Re and Cu. [1] Kiseeva E. S., Wood B. J. (2013). EPSL 383, p. 68-81. [2] Kiseeva E. S., Wood B. J. (2015). EPSL 424, p. 280-294. [3] Wood B. J., Kiseeva E. S. (2015). AmMin (in press).

Status of Line identifications in the ChandraLETG Spectrum of Procyon

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

Desai, P; Beiersdorfer, P; Brickhouse, N S

We report on our ongoing efforts to produce a relatively complete set of X-ray emission lines present in the Low Energy Transmission Grating (LETG) spectra of Procyon. In addition to using recently reprocessed HRC-S/LETG spectra of Procyon, we use LETG spectra of Capella, along with recent Electron Bean Ion Trap (EBIT) laboratory data and new Flexible Atomic Code (FAC) calculations to identify the wealth of weaker lines present in the spectrum. Experimental measurements at the EBIT-I and EBIT-II facilities at Livermore of astrophysically abundant elements (Fe VII-Fe X, Lepson et al. 2002, Ar IX-Ar XVI, Lepson et al 2003, Smore » VII, S XIV, Lepson et al 2004) and new FAC calculations of Mg and Ne (Gu, 2008 in press) provide an opportunity to identify many of the previously unassigned lines in Procyon (Raassen et al, 2002).« less

Concretionary manganese-iron oxides in streams and their usefulness as a sample medium for geochemical prospecting

USGS Publications Warehouse

Nowlan, G.A.

1976-01-01

Correlation studies of 400 samples of sieved stream sediments and 325 samples of fluvial, concretionary Mn-Fe oxides from Maine resulted in the separation of elements into the following categories: (1) elements not scavenged by Mn-Fe oxides - B, Cr, K, Mg, Rb, Sc, Ti, V, and Zr; (2) elements probably not scavenged by Mn-Fe oxides - Ag, Be, Ca, Ga, La, Sb, and Y; (3) elements scavenged weakly by Mn-Fe oxides - Cu, Mo, Pb, and Sr; (4) elements scavenged strongly by Mn oxides - Ba, Cd, Co, Ni, Tl, and Zn; and (5) elements scavenged strongly by Fe oxides - As and In. Studies of the scavenged elements showed that the deviation from the mean is characteristically greater in oxide samples as compared to sieved sediments from the same locality. However, a significant increase in contrast between anomalous and background localities, when oxides are the sample medium, more than offsets the disadvantage of data scatter. The use of oxides as a sampling medium clearly and significantly accentuates anomalous localities. In general, non-ratioed data on oxides give very nearly the same results as data consisting of scavenged elements ratioed to Mn and Fe. However, ratioed data expand the geographic area of specific anomalies. Cd and Zn consistently show strong correlations with concretionary Mn-Fe oxides, but their concentrations in the oxides do not generally show as much contrast between anomalous and background localities as do Cu, Mo, and Pb. These latter elements are strongly scavenged where rocks are mineralized. ?? 1976.

Finite-element three-dimensional ground-water (FE3DGW) flow model - formulation, program listings and users' manual

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

Gupta, S.K.; Cole, C.R.; Bond, F.W.

1979-12-01

The Assessment of Effectiveness of Geologic Isolation Systems (AEGIS) Program is developing and applying the methodology for assessing the far-field, long-term post-closure safety of deep geologic nuclear waste repositories. AEGIS is being performed by Pacific Northwest Laboratory (PNL) under contract with the Office of Nuclear Waste Isolation (OWNI) for the Department of Energy (DOE). One task within AEGIS is the development of methodology for analysis of the consequences (water pathway) from loss of repository containment as defined by various release scenarios. Analysis of the long-term, far-field consequences of release scenarios requires the application of numerical codes which simulate the hydrologicmore » systems, model the transport of released radionuclides through the hydrologic systems to the biosphere, and, where applicable, assess the radiological dose to humans. Hydrologic and transport models are available at several levels of complexity or sophistication. Model selection and use are determined by the quantity and quality of input data. Model development under AEGIS and related programs provides three levels of hydrologic models, two levels of transport models, and one level of dose models (with several separate models). This document consists of the description of the FE3DGW (Finite Element, Three-Dimensional Groundwater) Hydrologic model third level (high complexity) three-dimensional, finite element approach (Galerkin formulation) for saturated groundwater flow.« less

Rocket-Plume Spectroscopy Simulation for Hydrocarbon-Fueled Rocket Engines

NASA Technical Reports Server (NTRS)

Tejwani, Gopal D.

2010-01-01

The UV-Vis spectroscopic system for plume diagnostics monitors rocket engine health by using several analytical tools developed at Stennis Space Center (SSC), including the rocket plume spectroscopy simulation code (RPSSC), to identify and quantify the alloys from the metallic elements observed in engine plumes. Because the hydrocarbon-fueled rocket engine is likely to contain C2, CO, CH, CN, and NO in addition to OH and H2O, the relevant electronic bands of these molecules in the spectral range of 300 to 850 nm in the RPSSC have been included. SSC incorporated several enhancements and modifications to the original line-by-line spectral simulation computer program implemented for plume spectral data analysis and quantification in 1994. These changes made the program applicable to the Space Shuttle Main Engine (SSME) and the Diagnostic Testbed Facility Thruster (DTFT) exhaust plume spectral data. Modifications included updating the molecular and spectral parameters for OH, adding spectral parameter input files optimized for the 10 elements of interest in the spectral range from 320 to 430 nm and linking the output to graphing and analysis packages. Additionally, the ability to handle the non-uniform wavelength interval at which the spectral computations are made was added. This allowed a precise superposition of wavelengths at which the spectral measurements have been made with the wavelengths at which the spectral computations are done by using the line-by-line (LBL) code. To account for hydrocarbon combustion products in the plume, which might interfere with detection and quantification of metallic elements in the spectral region of 300 to 850 nm, the spectroscopic code has been enhanced to include the carbon-based combustion species of C2, CO, and CH. In addition, CN and NO have spectral bands in 300 to 850 nm and, while these molecules are not direct products of hydrocarbon-oxygen combustion systems, they can show up if nitrogen or a nitrogen compound is present as an impurity in the propellants and/or these can form in the boundary layer as a result of interaction of the hot plume with the atmosphere during the ground testing of engines. Ten additional electronic band systems of these five molecules have been included into the code. A comprehensive literature search was conducted to obtain the most accurate values for the molecular and the spectral parameters, including Franck-Cordon factors and electronic transition moments for all ten band systems. For each elemental transition in the RPSSC, six spectral parameters - Doppler broadened line width at half-height, pressure-broadened line width at half-height, electronic multiplicity of the upper state, electronic term energy of the upper state, Einstein transition probability coefficient, and the atomic line center - are required. Input files have been created for ten elements of Ni, Fe, Cr, Co, Cu, Ca, Mn, Al, Ag, and Pd, which retain only relatively moderate to strong transitions in 300 to 430 nm spectral range for each element. The number of transitions in the input files is 68 for Ni; 148 for Fe; 6 for Cr; 87 for Co; 1 for Ca; 3 for Mn; 2 each for Cu, Al, and Ag; and 11 for Pd.

Pile-Driving Pressure and Particle Velocity at the Seabed: Quantifying Effects on Crustaceans and Groundfish.

PubMed

Miller, James H; Potty, Gopu R; Kim, Hui-Kwan

2016-01-01

We modeled the effects of pile driving on crustaceans, groundfish, and other animals near the seafloor. Three different waves were investigated, including the compressional wave, shear wave, and interface wave. A finite element (FE) technique was employed in and around the pile, whereas a parabolic equation (PE) code was used to predict propagation at long ranges from the pile. Pressure, particle displacement, and particle velocity are presented as a function of range at the seafloor for a shallow-water environment near Rhode Island. We discuss the potential effects on animals near the seafloor.

THE CHEMICAL ABUNDANCES OF STARS IN THE HALO (CASH) PROJECT. II. A SAMPLE OF 14 EXTREMELY METAL-POOR STARS ,

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

Hollek, Julie K.; Sneden, Christopher; Shetrone, Matthew

2011-11-20

We present a comprehensive abundance analysis of 20 elements for 16 new low-metallicity stars from the Chemical Abundances of Stars in the Halo (CASH) project. The abundances have been derived from both Hobby-Eberly Telescope High Resolution Spectrograph snapshot spectra (R {approx}15, 000) and corresponding high-resolution (R {approx}35, 000) Magellan Inamori Kyocera Echelle spectra. The stars span a metallicity range from [Fe/H] from -2.9 to -3.9, including four new stars with [Fe/H] < -3.7. We find four stars to be carbon-enhanced metal-poor (CEMP) stars, confirming the trend of increasing [C/Fe] abundance ratios with decreasing metallicity. Two of these objects can bemore » classified as CEMP-no stars, adding to the growing number of these objects at [Fe/H]< - 3. We also find four neutron-capture-enhanced stars in the sample, one of which has [Eu/Fe] of 0.8 with clear r-process signatures. These pilot sample stars are the most metal-poor ([Fe/H] {approx}< -3.0) of the brightest stars included in CASH and are used to calibrate a newly developed, automated stellar parameter and abundance determination pipeline. This code will be used for the entire {approx}500 star CASH snapshot sample. We find that the pipeline results are statistically identical for snapshot spectra when compared to a traditional, manual analysis from a high-resolution spectrum.« less

Safety assessment of historical masonry churches based on pre-assigned kinematic limit analysis, FE limit and pushover analyses

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

Milani, Gabriele, E-mail: milani@stru.polimi.it; Valente, Marco, E-mail: milani@stru.polimi.it

2014-10-06

This study presents some results of a comprehensive numerical analysis on three masonry churches damaged by the recent Emilia-Romagna (Italy) seismic events occurred in May 2012. The numerical study comprises: (a) pushover analyses conducted with a commercial code, standard nonlinear material models and two different horizontal load distributions; (b) FE kinematic limit analyses performed using a non-commercial software based on a preliminary homogenization of the masonry materials and a subsequent limit analysis with triangular elements and interfaces; (c) kinematic limit analyses conducted in agreement with the Italian code and based on the a-priori assumption of preassigned failure mechanisms, where themore » masonry material is considered unable to withstand tensile stresses. All models are capable of giving information on the active failure mechanism and the base shear at failure, which, if properly made non-dimensional with the weight of the structure, gives also an indication of the horizontal peak ground acceleration causing the collapse of the church. The results obtained from all three models indicate that the collapse is usually due to the activation of partial mechanisms (apse, façade, lateral walls, etc.). Moreover the horizontal peak ground acceleration associated to the collapse is largely lower than that required in that seismic zone by the Italian code for ordinary buildings. These outcomes highlight that structural upgrading interventions would be extremely beneficial for the considerable reduction of the seismic vulnerability of such kind of historical structures.« less

Chemical Analysis of a Carbon-enhanced Very Metal-poor Star: CD-27 14351

NASA Astrophysics Data System (ADS)

Karinkuzhi, Drisya; Goswami, Aruna; Masseron, Thomas

2017-01-01

We present, for the first time, an abundance analysis of a very metal-poor carbon-enhanced star CD-27 14351 based on a high-resolution (R ˜ 48,000) FEROS spectrum. Our abundance analysis performed using local thermodynamic equilibrium model atmospheres shows that the object is a cool star with stellar atmospheric parameters, effective temperature Teff = 4335 K, surface gravity log g = 0.5, microturbulence ξ = 2.42 km s-1, and metallicity [Fe/H] = -2.6. The star exhibits high carbon and nitrogen abundances with [C/Fe] = 2.89 and [N/Fe] = 1.89. Overabundances of neutron-capture elements are evident in Ba, La, Ce, and Nd, with estimated [X/Fe] > 1, the largest enhancement being seen in Ce with [Ce/Fe] = 2.63. While the first peak s-process elements Sr and Y are found to be enhanced with respect to Fe, ([Sr/Fe] = 1.73 and [Y/Fe] = 1.91), the third peak s-process element Pb could not be detected in our spectrum at the given resolution. Europium, primarily an r-process element also shows an enhancement with [Eu/Fe] = 1.65. With [Ba/Eu] = 0.12, the object CD-27 14351 satisfies the classification criterion for a CEMP-r/s star. The elemental abundance distributions observed in this star are discussed in light of the chemical abundances observed in other CEMP stars in the literature.

Constitutive modeling of aluminum foam and finite element implementation for crash simulations

NASA Astrophysics Data System (ADS)

Bi, Jing

In the past decades metallic foams have been increasingly used as filler materials in crashworthiness applications due to their relatively low cost and high capacity of energy absorption. Due to the destructive nature of crashes, studies on the performance of metallic foams using physical testing have been limited to examining the crushing force histories and/or folding patterns that are insufficient for crashworthiness designs. For this reason, numerical simulations, particularly nonlinear finite element (FE) analyses, play an important role in designing crashworthy foam-filled structures. An effective and numerically stable model is needed for modeling metallic foams that are porous and encounter large nonlinear deformations in crashes. In this study a new constitutive model for metallic foams is developed to overcome the deficiency of existing models in commercial FE codes such as LS-DYNA. The new constitutive model accounts for volume changes under hydrostatic compression and combines the hydrostatic pressure and von Mises stress into one yield function. The change of the compressibility of the metallic foam is handled in the constitutive model by allowing for shape changes of the yield surface in the hydrostatic pressure-von Mises stress space. The backward Euler method is adopted to integrate the constitutive equations to achieve numerical accuracy and stability. The new foam model is verified and validated by existing experimental data before used in FE simulations of crushing of foam-filled columns that have square and hexagonal cross-sections.

Sulphursoil - Delano Development Corporation

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

None

1985-06-01

A sizable amount of technical information has been accumulated on the effects of agricultural applications of the natural mineral product called Sul-Fe. This technical information supports the field observations of farmers, landscapers and gardeners who have used the product. Sul-Fe is often evaluated in terms of its sulphur content alone. When compared to elemental sulphur (100% sulphur), the 18 to 21% sulphur content of Sul-Fe seems relatively low. However, as the following technical data indicates, when judged on actual effects, Sul-Fe's complex mixture of minerals has several advantages over elemental sulphur. When judged on the basis of soil acidulation, Sul-Femore » has more immediate effects than elemental sulphur. The rapid acidifying effect is due to Sul-Fe's content of crystalline sulphuric acid. Sul-Fe also has long-term effects on soil pH due to its content of sulphur and sulfides and the time required to oxidize these materials. Elemental sulphur contains sulphur in only one chemical form which must be microbially oxidized before it becomes reactive in the soil solution, a reaction that takes quite some time in some soils. Sul-Fe is thus better than elemental sulphur in terms of immediate effects and comparable in terms of long term effects. Applied blends of Sul-Fe supplemented with elemental sulphur may provide for a maximization of both short and long term effects. An additional benefit derived from the use of Sul-Fe is the addition to the soil of a variety of trace nutrients including iron, calcium, zinc, copper, manganese, magnesium, and molybdenum.« less

Stellar and laboratory XUV/EUV line ratios in Fe XVIII and Fe XIX

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

Traebert, E.; Beiersdorfer, P.; Clementson, J.

2012-05-25

A so-called XUV excess has been suspected with the relative fluxes of Fe XVIII and Fe XIX lines observed in the XUV and EUV ranges of the spectrum of the star Capella as observed by the Chandra spacecraft, even after correction for interstellar absorption. This excess becomes apparent in the comparison of the observations with simulations of stellar spectra obtained using collisional-radiative models that employ, for example, the Atomic Plasma Emission Code (APEC) or the Flexible Atomic Code (FAC). We have addressed this problem by laboratory studies using the Livermore electron beam ion trap (EBIT).

Iron mineral structure, reactivity, and isotopic composition in a South Pacific Gyre ferromanganese nodule over 4 Ma

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

Marcus, Matthew A.; Edwards, Katrina J.; Gueguen, Bleuenn

Deep-sea ferromanganese nodules accumulate trace elements from seawater and underlying sediment porewaters during the growth of concentric mineral layers over millions of years. These trace elements have the potential to record past ocean geochemical conditions. The goal of this study was to determine whether Fe mineral alteration occurs and how the speciation of trace elements responds to alteration over ~3.7Ma of marine ferromanganese nodule (MFN) formation, a timeline constrained by estimates from 9 Be/ 10 Be concentrations in the nodule material. We determined Fe-bearing phases and Fe isotope composition in a South Pacific Gyre (SPG) nodule. Specifically, the distribution patternsmore » and speciation of trace element uptake by these Fe phases were investigated. The time interval covered by the growth of our sample of the nodule was derived from 9 Be/ 10 Be accelerator mass spectrometry (AMS). The composition and distribution of major and trace elements were mapped at various spatial scales, using micro-X-ray fluorescence (μXRF), electron microprobe analysis (EMPA), and inductively coupled plasma mass spectrometry (ICP-MS). Fe phases were characterized by micro-extended X-ray absorption fine structure (μEXAFS) spectroscopy and micro-X-ray diffraction (μXRD). Speciation of Ti and V, associated with Fe, was measured using micro-X-ray absorption near edge structure (μXANES) spectroscopy. Iron isotope composition (δ 56/54 Fe) in subsamples of 1-3mm increments along the radius of the nodule was determined with multiple-collector ICP-MS (MC-ICP-MS). The SPG nodule formed through primarily hydrogeneous inputs at a rate of 4.0±0.4mm/Ma. The nodule exhibited a high diversity of Fe mineral phases: feroxyhite (δ-FeOOH), goethite (α-FeOOH), lepidocrocite (γ-FeOOH), and poorly ordered ferrihydrite-like phases. These findings provide evidence that Fe oxyhydroxides within the nodule undergo alteration to more stable phases over millions of years. Trace Ti and V were spatially correlated with Fe and found to be adsorbed to Fe-bearing minerals. Ti/Fe and V/Fe ratios, and Ti and V speciation, did not vary along the nodule radius. The δ 56/54 Fe values, when averaged over sample increments representing 0.25-0.75Ma, were homogeneous within uncertainty along the nodule radius, at -0.12±0.07‰ (2sd, n=10). Our results indicate that the Fe isotope composition of the nodule remained constant during nodule growth and that mineral alteration did not affect the primary Fe isotope composition of the nodule. Furthermore, the average δ 56/54 Fe value of -0.12‰ we find is consistent with Fe sourced from continental eolian particles (dust). Despite mineral alteration, the trace element partitioning of Ti and V, and Fe isotope composition, do not appear to change within the sensitivity of our measurements. These findings suggest that Fe oxyhydroxides within hydrogenetic ferromanganese nodules are out of geochemical contact with seawater once they are covered by subsequent concentric mineral layers. Even though Fe-bearing minerals are altered, trace element ratios, speciation and Fe isotope composition are preserved within the nodule.« less

Iron mineral structure, reactivity, and isotopic composition in a South Pacific Gyre ferromanganese nodule over 4 Ma

DOE PAGES

Marcus, Matthew A.; Edwards, Katrina J.; Gueguen, Bleuenn; ...

2015-09-05

Deep-sea ferromanganese nodules accumulate trace elements from seawater and underlying sediment porewaters during the growth of concentric mineral layers over millions of years. These trace elements have the potential to record past ocean geochemical conditions. The goal of this study was to determine whether Fe mineral alteration occurs and how the speciation of trace elements responds to alteration over ~3.7Ma of marine ferromanganese nodule (MFN) formation, a timeline constrained by estimates from 9 Be/ 10 Be concentrations in the nodule material. We determined Fe-bearing phases and Fe isotope composition in a South Pacific Gyre (SPG) nodule. Specifically, the distribution patternsmore » and speciation of trace element uptake by these Fe phases were investigated. The time interval covered by the growth of our sample of the nodule was derived from 9 Be/ 10 Be accelerator mass spectrometry (AMS). The composition and distribution of major and trace elements were mapped at various spatial scales, using micro-X-ray fluorescence (μXRF), electron microprobe analysis (EMPA), and inductively coupled plasma mass spectrometry (ICP-MS). Fe phases were characterized by micro-extended X-ray absorption fine structure (μEXAFS) spectroscopy and micro-X-ray diffraction (μXRD). Speciation of Ti and V, associated with Fe, was measured using micro-X-ray absorption near edge structure (μXANES) spectroscopy. Iron isotope composition (δ 56/54 Fe) in subsamples of 1-3mm increments along the radius of the nodule was determined with multiple-collector ICP-MS (MC-ICP-MS). The SPG nodule formed through primarily hydrogeneous inputs at a rate of 4.0±0.4mm/Ma. The nodule exhibited a high diversity of Fe mineral phases: feroxyhite (δ-FeOOH), goethite (α-FeOOH), lepidocrocite (γ-FeOOH), and poorly ordered ferrihydrite-like phases. These findings provide evidence that Fe oxyhydroxides within the nodule undergo alteration to more stable phases over millions of years. Trace Ti and V were spatially correlated with Fe and found to be adsorbed to Fe-bearing minerals. Ti/Fe and V/Fe ratios, and Ti and V speciation, did not vary along the nodule radius. The δ 56/54 Fe values, when averaged over sample increments representing 0.25-0.75Ma, were homogeneous within uncertainty along the nodule radius, at -0.12±0.07‰ (2sd, n=10). Our results indicate that the Fe isotope composition of the nodule remained constant during nodule growth and that mineral alteration did not affect the primary Fe isotope composition of the nodule. Furthermore, the average δ 56/54 Fe value of -0.12‰ we find is consistent with Fe sourced from continental eolian particles (dust). Despite mineral alteration, the trace element partitioning of Ti and V, and Fe isotope composition, do not appear to change within the sensitivity of our measurements. These findings suggest that Fe oxyhydroxides within hydrogenetic ferromanganese nodules are out of geochemical contact with seawater once they are covered by subsequent concentric mineral layers. Even though Fe-bearing minerals are altered, trace element ratios, speciation and Fe isotope composition are preserved within the nodule.« less

A General Interface Method for Aeroelastic Analysis of Aircraft

NASA Technical Reports Server (NTRS)

Tzong, T.; Chen, H. H.; Chang, K. C.; Wu, T.; Cebeci, T.

1996-01-01

The aeroelastic analysis of an aircraft requires an accurate and efficient procedure to couple aerodynamics and structures. The procedure needs an interface method to bridge the gap between the aerodynamic and structural models in order to transform loads and displacements. Such an interface method is described in this report. This interface method transforms loads computed by any aerodynamic code to a structural finite element (FE) model and converts the displacements from the FE model to the aerodynamic model. The approach is based on FE technology in which virtual work is employed to transform the aerodynamic pressures into FE nodal forces. The displacements at the FE nodes are then converted back to aerodynamic grid points on the aircraft surface through the reciprocal theorem in structural engineering. The method allows both high and crude fidelities of both models and does not require an intermediate modeling. In addition, the method performs the conversion of loads and displacements directly between individual aerodynamic grid point and its corresponding structural finite element and, hence, is very efficient for large aircraft models. This report also describes the application of this aero-structure interface method to a simple wing and an MD-90 wing. The results show that the aeroelastic effect is very important. For the simple wing, both linear and nonlinear approaches are used. In the linear approach, the deformation of the structural model is considered small, and the loads from the deformed aerodynamic model are applied to the original geometry of the structure. In the nonlinear approach, the geometry of the structure and its stiffness matrix are updated in every iteration and the increments of loads from the previous iteration are applied to the new structural geometry in order to compute the displacement increments. Additional studies to apply the aero-structure interaction procedure to more complicated geometry will be conducted in the second phase of the present contract.

Early Diagenesis of Trace Elements in Modern Fjord Sediments of the High Arctic

NASA Astrophysics Data System (ADS)

Herbert, L.; Riedinger, N.; Aller, R. C.; Jørgensen, B. B.; Wehrmann, L.

2017-12-01

Marine sediments are critical repositories for elements that are only available at trace concentrations in seawater, such as Fe, Mn, Co, Ni, As, Mo, and U. The behavior of these trace elements in the sediment is governed by a dynamic interplay of diagenetic reactions involving organic carbon, Fe and Mn oxides, and sulfur phases. In the Arctic fjords of Svalbard, glacial meltwater delivers large amounts of reactive Fe and Mn oxides to the sediment, while organic carbon is deposited episodically and diluted by lithogenic material. These conditions result in pronounced Fe and Mn cycling, which in turn drives other diagenetic processes such as rapid sulfide oxidation. These conditions make the Svalbard fjords ideal sites for investigating trace element diagenesis because they allow resolution of the interconnections between Fe and Mn dynamics and trace element cycling. In August 2016, we collected sediment cores from three Svalbard fjords and analyzed trace elements in the pore water and solid sediment over the top meter. Initial results reveal the dynamic nature of these fjords, which are dominated by non-steady state processes and episodic events such as meltwater pulses and phytoplankton blooms. Within this system, the distribution of As appears to be strongly linked to the Fe cycle, while Co and Ni follow Mn; thus, these three elements may be released from the sediment through diffusion and bioturbation along with Fe and Mn. The pore water profiles of U and Mo indicate removal processes that are independent from Fe or Mn, and which are rather unexpected given the apparent diagenetic conditions. Our results will help elucidate the processes controlling trace element cycling in a dynamic, glacially impacted environment and will ultimately contribute to our understanding of the role of fjords in the biogeochemical cycling of trace elements in a rapidly changing Arctic Ocean.

A Proposal of Monitoring and Forecasting Method for Crustal Activity in and around Japan with 3-dimensional Heterogeneous Medium Using a Large-scale High-fidelity Finite Element Simulation

NASA Astrophysics Data System (ADS)

Hori, T.; Agata, R.; Ichimura, T.; Fujita, K.; Yamaguchi, T.; Takahashi, N.

2017-12-01

Recently, we can obtain continuous dense surface deformation data on land and partly on the sea floor, the obtained data are not fully utilized for monitoring and forecasting of crustal activity, such as spatio-temporal variation in slip velocity on the plate interface including earthquakes, seismic wave propagation, and crustal deformation. For construct a system for monitoring and forecasting, it is necessary to develop a physics-based data analysis system including (1) a structural model with the 3D geometry of the plate inter-face and the material property such as elasticity and viscosity, (2) calculation code for crustal deformation and seismic wave propagation using (1), (3) inverse analysis or data assimilation code both for structure and fault slip using (1) & (2). To accomplish this, it is at least necessary to develop highly reliable large-scale simulation code to calculate crustal deformation and seismic wave propagation for 3D heterogeneous structure. Unstructured FE non-linear seismic wave simulation code has been developed. This achieved physics-based urban earthquake simulation enhanced by 1.08 T DOF x 6.6 K time-step. A high fidelity FEM simulation code with mesh generator has also been developed to calculate crustal deformation in and around Japan with complicated surface topography and subducting plate geometry for 1km mesh. This code has been improved the code for crustal deformation and achieved 2.05 T-DOF with 45m resolution on the plate interface. This high-resolution analysis enables computation of change of stress acting on the plate interface. Further, for inverse analyses, waveform inversion code for modeling 3D crustal structure has been developed, and the high-fidelity FEM code has been improved to apply an adjoint method for estimating fault slip and asthenosphere viscosity. Hence, we have large-scale simulation and analysis tools for monitoring. We are developing the methods for forecasting the slip velocity variation on the plate interface. Although the prototype is for elastic half space model, we are applying it for 3D heterogeneous structure with the high-fidelity FE model. Furthermore, large-scale simulation codes for monitoring are being implemented on the GPU clusters and analysis tools are developing to include other functions such as examination in model errors.

Traumatic eye injuries as a result of blunt impact: computational issues

NASA Astrophysics Data System (ADS)

Clemente, C.; Esposito, L.; Bonora, N.; Limido, J.; Lacome, J. L.; Rossi, T.

2014-05-01

The detachment or tearing of the retina in the human eye as a result of a collision is a phenomenon that occurs very often. Reliable numerical simulations of eye impact can be very useful tools to understand the physical mechanisms responsible for traumatic eye injuries accompanying blunt impact. The complexity and variability of the physical and mechanical properties of the biological materials, the lack of agreement on their related experimental data as well as the unsuitability of specific numerical codes and models are only some of the difficulties when dealing with this matter. All these challenging issues must be solved to obtain accurate numerical analyses involving dynamic behavior of biological soft tissues. To this purpose, a numerical and experimental investigation of the dynamic response of the eye during an impact event was performed. Numerical simulations were performed with IMPETUS-AFEA, a new general non-linear finite element (FE) software which offers non uniform rational B-splines (NURBS) FE technology for the simulation of large deformation and fracture in materials. IMPETUS code was selected in order to solve hourglass and locking problems typical of nearly incompressible materials like eye tissues. Computational results were compared with the experimental results on fresh enucleated porcine eyes impacted with airsoft pellets.

QRAP: A numerical code for projected (Q)uasiparticle (RA)ndom (P)hase approximation

NASA Astrophysics Data System (ADS)

Samana, A. R.; Krmpotić, F.; Bertulani, C. A.

2010-06-01

A computer code for quasiparticle random phase approximation - QRPA and projected quasiparticle random phase approximation - PQRPA models of nuclear structure is explained in details. The residual interaction is approximated by a simple δ-force. An important application of the code consists in evaluating nuclear matrix elements involved in neutrino-nucleus reactions. As an example, cross sections for 56Fe and 12C are calculated and the code output is explained. The application to other nuclei and the description of other nuclear and weak decay processes are also discussed. Program summaryTitle of program: QRAP ( Quasiparticle RAndom Phase approximation) Computers: The code has been created on a PC, but also runs on UNIX or LINUX machines Operating systems: WINDOWS or UNIX Program language used: Fortran-77 Memory required to execute with typical data: 16 Mbytes of RAM memory and 2 MB of hard disk space No. of lines in distributed program, including test data, etc.: ˜ 8000 No. of bytes in distributed program, including test data, etc.: ˜ 256 kB Distribution format: tar.gz Nature of physical problem: The program calculates neutrino- and antineutrino-nucleus cross sections as a function of the incident neutrino energy, and muon capture rates, using the QRPA or PQRPA as nuclear structure models. Method of solution: The QRPA, or PQRPA, equations are solved in a self-consistent way for even-even nuclei. The nuclear matrix elements for the neutrino-nucleus interaction are treated as the beta inverse reaction of odd-odd nuclei as function of the transfer momentum. Typical running time: ≈ 5 min on a 3 GHz processor for Data set 1.

Enhanced Schapery Theory Software Development for Modeling Failure of Fiber-Reinforced Laminates

NASA Technical Reports Server (NTRS)

Pineda, Evan J.; Waas, Anthony M.

2013-01-01

Progressive damage and failure analysis (PDFA) tools are needed to predict the nonlinear response of advanced fiber-reinforced composite structures. Predictive tools should incorporate the underlying physics of the damage and failure mechanisms observed in the composite, and should utilize as few input parameters as possible. The purpose of the Enhanced Schapery Theory (EST) was to create a PDFA tool that operates in conjunction with a commercially available finite element (FE) code (Abaqus). The tool captures the physics of the damage and failure mechanisms that result in the nonlinear behavior of the material, and the failure methodology employed yields numerical results that are relatively insensitive to changes in the FE mesh. The EST code is written in Fortran and compiled into a static library that is linked to Abaqus. A Fortran Abaqus UMAT material subroutine is used to facilitate the communication between Abaqus and EST. A clear distinction between damage and failure is imposed. Damage mechanisms result in pre-peak nonlinearity in the stress strain curve. Four internal state variables (ISVs) are utilized to control the damage and failure degradation. All damage is said to result from matrix microdamage, and a single ISV marks the micro-damage evolution as it is used to degrade the transverse and shear moduli of the lamina using a set of experimentally obtainable matrix microdamage functions. Three separate failure ISVs are used to incorporate failure due to fiber breakage, mode I matrix cracking, and mode II matrix cracking. Failure initiation is determined using a failure criterion, and the evolution of these ISVs is controlled by a set of traction-separation laws. The traction separation laws are postulated such that the area under the curves is equal to the fracture toughness of the material associated with the corresponding failure mechanism. A characteristic finite element length is used to transform the traction-separation laws into stress-strain laws. The ISV evolution equations are derived in a thermodynamically consistent manner by invoking the stationary principle on the total work of the system with respect to each ISV. A novel feature is the inclusion of both pre-peak damage and appropriately scaled, post-peak strain softening failure. Also, the characteristic elements used in the failure degradation scheme are calculated using the element nodal coordinates, rather than simply the square root of the area of the element.

Simulation of Low Velocity Impact Induced Inter- and Intra-Laminar Damage of Composite Beams Based on XFEM

NASA Astrophysics Data System (ADS)

Sun, Wei; Guan, Zhidong; Li, Zengshan

2017-12-01

In this paper, the Inter-Fiber Fracture (IFF) criterion of Puck failure theory based on the eXtended Finite Element Method (XFEM) was implemented in ABAQUS code to predict the intra-laminar crack initiation of unidirectional (UD) composite laminate. The transverse crack path in the matrix can be simulated accurately by the presented method. After the crack initiation, the propagation of the crack is simulated by Cohesive Zoom Model (CZM), in which the displacement discontinuities and stress concentration caused by matrix crack is introduced into the finite element (FE) model. Combined with the usage of the enriched element interface, which can be used to simulate the inter-laminar delamination crack, the Low Velocity Impact (LVI) induced damage of UD composite laminate beam with a typical stacking of composite laminates [05/903]S is studied. A complete crack initiation and propagation process was simulated and the numerical results obtained by the XFEM are consistent with the experimental results.

Dissolved trace elements in a nitrogen-polluted river near to the Liaodong Bay in Northeast China.

PubMed

Bu, Hongmei; Song, Xianfang; Guo, Fen

2017-01-15

Dissolved trace element concentrations (Ba, Fe, Mn, Si, Sr, and Zn) were investigated in the Haicheng River near to the Liaodong Bay in Northeast China during 2010. Dissolved Ba, Fe, Mn, and Sr showed significant spatial variation, whereas dissolved Fe, Mn, and Zn displayed seasonal variations. Conditions such as water temperature, pH, and dissolved oxygen were found to have an important impact on redox reactions involving dissolved Ba, Fe, and Zn. Dissolved Fe and Mn concentrations were regulated by adsorption or desorption of Fe/Mn oxyhydroxides and the effects of organic carbon complexation on dissolved Ba and Sr were found to be significant. The sources of dissolved trace elements were found to be mainly from domestic sewage, industrial waste, agricultural surface runoff, and natural origin, with estimated seasonal and annual river fluxes established as important inputs of dissolved trace elements from the Haicheng River into the Liaodong Bay or Bohai Sea. Copyright © 2016 Elsevier Ltd. All rights reserved.

Finite element analysis of pedestrian lower limb fractures by direct force: the result of being run over or impact?

PubMed

Li, Zhengdong; Zou, Donghua; Liu, Ningguo; Zhong, Liangwei; Shao, Yu; Wan, Lei; Huang, Ping; Chen, Yijiu

2013-06-10

The elucidation and prediction of the biomechanics of lower limb fractures could serve as a useful tool in forensic practices. Finite element (FE) analysis could potentially help in the understanding of the fracture mechanisms of lower limb fractures frequently caused by car-pedestrian accidents. Our aim was (1) to develop and validate a FE model of the human lower limb, (2) to assess the biomechanics of specific injuries concerning run-over and impact loading conditions, and (3) to reconstruct one real car-pedestrian collision case using the model created in this study. We developed a novel lower limb FE model and simulated three different loading scenarios. The geometry of the model was reconstructed using Mimics 13.0 based on computed tomography (CT) scans from an actual traffic accident. The material properties were based upon a synthesis of data found in published literature. The FE model validation and injury reconstruction were conducted using the LS-DYNA code. The FE model was validated by a comparison of the simulation results of three-point bending, overall lateral impact tests and published postmortem human surrogate (PMHS) results. Simulated loading scenarios of running-over the thigh with a wheel, the impact on the upper leg, and impact on the lower thigh were conducted with velocities of 10 m/s, 20 m/s, and 40 m/s, respectively. We compared the injuries resulting from one actual case with the simulated results in order to explore the possible fracture bio-mechanism. The peak fracture forces, maximum bending moments, and energy lost ratio exhibited no significant differences between the FE simulations and the literature data. Under simulated run-over conditions, the segmental fracture pattern was formed and the femur fracture patterns and mechanisms were consistent with the actual injury features of the case. Our study demonstrated that this simulation method could potentially be effective in identifying forensic cases and exploring of the injury mechanisms of lower limb fractures encountered due to inflicted lesions. This model can also help to distinguish between possible and impossible scenarios. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Radiative accelerations in stellar envelopes

NASA Astrophysics Data System (ADS)

Seaton, M. J.

1997-08-01

In stars which are sufficiently quiescent, changes in the relative abundances of the chemical elements can result from gravitational settling and from levitation produced by radiation pressure forces, usually expressed as radiative accelerations g_rad. Those changes can affect the structure of such stars, due to modifications in opacities, and can lead to marked peculiarities in observed atmospheric abundances. It is necessary to consider diffusive movements both in the atmospheres and in much deeper layers of the stellar envelopes. For the envelopes the equation of radiative transfer can be solved in a diffusion approximation and, for an element k in ionization stage j, one obtains expressions for g_rad(j, k) proportional to the total radiative flux, to the Rosseland-mean opacity kappa_R (which may depend on the abundance of k), and to a dimensionless quantity gamma(j, k) which, due to saturation effects, can be sensitive to the abundance of k. The radiative accelerations are required for each ionization stage, because the diffusion coefficients depend on j. Using atomic data obtained in the course of the work of the Opacity Project (OP), we calculate kappa_R and gamma(j, k) for the chemical elements C, N, O, Ne, Na, Mg, Al, Si, S, Ar, Ca, Cr, Mn, Fe and Ni. We start from standard Solar system abundances, and then vary the abundance of one element at a time (element k) by a factor chi. The following results are obtained and are available at the Centre de Donnees astronomiques de Strasbourg (CDS). (1) Files stages.zz (where zz specifies the nuclear charge of the selected element k) containing values of kappa_R and gamma(j, k) on a mesh of values of (T, N_e, chi), where T is temperature, and N_e is electron density. We include derivatives of kappa_R and gamma(j, k) with respect to chi, which are used for making interpolations. (2) A code add.f which reads a file stages.zz and writes a file acc.zz containing values of gamma(k) obtained on summing the gamma(j, k), weighted by diffusion coefficients. The diffusion coefficients to be employed can be selected by the user. (3) A code acc.f which reads a file acc.zz and provides facilities for interpolations of kappa_R and g_rad(k) to values of (T, rho, chi) for a stellar model, where rho is mass density. The mesh to be used for log(chi) is specified by the user. (4) A code diff.f intended for use in diffusion calculations. It reads a file created by acc.f and provides function subroutines for the calculation of kappa_R and g_rad(k) for any specified depth-point and any value of chi. Results are compared with those from other recent work for C, N, O, Ca and Fe.

A proposal of monitoring and forecasting system for crustal activity in and around Japan using a large-scale high-fidelity finite element simulation codes

NASA Astrophysics Data System (ADS)

Hori, Takane; Ichimura, Tsuyoshi; Takahashi, Narumi

2017-04-01

Here we propose a system for monitoring and forecasting of crustal activity, such as spatio-temporal variation in slip velocity on the plate interface including earthquakes, seismic wave propagation, and crustal deformation. Although, we can obtain continuous dense surface deformation data on land and partly on the sea floor, the obtained data are not fully utilized for monitoring and forecasting. It is necessary to develop a physics-based data analysis system including (1) a structural model with the 3D geometry of the plate interface and the material property such as elasticity and viscosity, (2) calculation code for crustal deformation and seismic wave propagation using (1), (3) inverse analysis or data assimilation code both for structure and fault slip using (1) & (2). To accomplish this, it is at least necessary to develop highly reliable large-scale simulation code to calculate crustal deformation and seismic wave propagation for 3D heterogeneous structure. Actually, Ichimura et al. (2015, SC15) has developed unstructured FE non-linear seismic wave simulation code, which achieved physics-based urban earthquake simulation enhanced by 1.08 T DOF x 6.6 K time-step. Ichimura et al. (2013, GJI) has developed high fidelity FEM simulation code with mesh generator to calculate crustal deformation in and around Japan with complicated surface topography and subducting plate geometry for 1km mesh. Fujita et al. (2016, SC16) has improved the code for crustal deformation and achieved 2.05 T-DOF with 45m resolution on the plate interface. This high-resolution analysis enables computation of change of stress acting on the plate interface. Further, for inverse analyses, Errol et al. (2012, BSSA) has developed waveform inversion code for modeling 3D crustal structure, and Agata et al. (2015, AGU Fall Meeting) has improved the high-fidelity FEM code to apply an adjoint method for estimating fault slip and asthenosphere viscosity. Hence, we have large-scale simulation and analysis tools for monitoring. Furthermore, we are developing the methods for forecasting the slip velocity variation on the plate interface. Basic concept is given in Hori et al. (2014, Oceanography) introducing ensemble based sequential data assimilation procedure. Although the prototype described there is for elastic half space model, we are applying it for 3D heterogeneous structure with the high-fidelity FE model.

Substitution of Nd with other rare earth elements in melt spun Nd{sub 2}Fe{sub 14}B magnets

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

Brown, D. N.; Lau, D.; Chen, Z.

2016-05-15

This is a contemporary study of rapidly quenched Nd{sub 1.6}X{sub 0.4}Fe{sub 14}B magnetic materials (where X= Nd, Y, Ce, La, Pr, Gd and Ho). A 20% substitution of the Nd component from Nd{sub 2}Fe{sub 14}B can bring about some commercial advantage. However, there will be some compromise to the magnetic performance. Light rare earth elements are definitely more abundant (Y, Ce, La) than the heavier rare earth elements, but when they are included in RE{sub 2}Fe{sub 14}B magnets they tend to lower magnetic performance and thermal stability. Substituting heavy rare earth elements (Gd, Ho) for Nd in Nd{sub 2}Fe{sub 14}Bmore » improves the thermal stability of magnets but causes a loss in magnet remanence.« less

CHEMICAL ANALYSIS OF A CARBON-ENHANCED VERY METAL-POOR STAR: CD-27 14351

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

Karinkuzhi, Drisya; Goswami, Aruna; Masseron, Thomas

2017-01-01

We present, for the first time, an abundance analysis of a very metal-poor carbon-enhanced star CD-27 14351 based on a high-resolution ( R  ∼ 48,000) FEROS spectrum. Our abundance analysis performed using local thermodynamic equilibrium model atmospheres shows that the object is a cool star with stellar atmospheric parameters, effective temperature T {sub eff} = 4335 K, surface gravity log g  = 0.5, microturbulence ξ  = 2.42 km s{sup −1}, and metallicity [Fe/H] = −2.6. The star exhibits high carbon and nitrogen abundances with [C/Fe] = 2.89 and [N/Fe] = 1.89. Overabundances of neutron-capture elements are evident in Ba, La, Ce, and Nd, with estimated [X/Fe] > 1, the largest enhancementmore » being seen in Ce with [Ce/Fe] = 2.63. While the first peak s -process elements Sr and Y are found to be enhanced with respect to Fe, ([Sr/Fe] = 1.73 and [Y/Fe] = 1.91), the third peak s -process element Pb could not be detected in our spectrum at the given resolution. Europium, primarily an r -process element also shows an enhancement with [Eu/Fe] = 1.65. With [Ba/Eu] = 0.12, the object CD-27 14351 satisfies the classification criterion for a CEMP-r/s star. The elemental abundance distributions observed in this star are discussed in light of the chemical abundances observed in other CEMP stars in the literature.« less

Siderophile Element Partitioning between Cohenite and Liquid in Fe-Ni-S-C System and Implications for Geochemistry of Planetary Cores and Mantles

NASA Astrophysics Data System (ADS)

Buono, A. S.; Dasgupta, R.; Walker, D.

2011-12-01

Secular cooling of terrestrial planets is known to cause crystallization of a solid inner core from metallic liquid core. Fractionation of light and siderophile elements is important during such crystallization for evolution of outer core and possible core-mantle interaction. Thus far studies focused on a pure Fe inner core in simple binary systems but the effects of possible formation of a carbide inner core component on siderophile element partitioning in a multi-component system has yet to be looked at in detail. We investigated the effects of pressure and S content on partition coefficients (D) between cohenite and liquid in the Fe-Ni-S-C system. Multi-anvil experiments were performed at 3 and 6 GPa at 1150 °C, in an Fe-rich mix containing a constant C and Ni to which S contents of 0, 5, and 14 wt.% were added. All the mixes were doped with W, Re, Os, Pt, and Co. Samples were imaged and analyzed for Fe, Ni, S, and C using an EPMA. Fe, Ni, and trace elements were analyzed using a LA-ICP-MS. All the experiments produced cohenite and Fe-Ni-C±S liquid. Compared to solid-Fe/melt Ds [1-2], cohenite/melt Ds are lower for all elements except W. The light element (S+C) content of the liquid is the dominant controlling factor in siderophile element partitioning between cohenite and liquid as it is between crystalline Fe and liquid. In the cohenite-metallic melt experiments, D Ni decreases as S+C increases. Ni is excluded from the crystallizing solid if the solid is cohenite. We also find that in the Fe-Ni-S-C system, cohenite is stabilized to higher P than in the Fe-S-C system [3-5]. Similar to the Fe-metallic liquid systems the non-metal avoidance model [6] is applicable to the Fe3C-metallic liquid system studied here. Our study has implications for both the cores of smaller planets and the mantles of larger planets. If inner core forms a cohenite layer we would predict that depletions in the outer core will be less than they might be for Fe metal crystallization. For the mantle of the earth, which is thought to become Fe-Ni metal-saturated as shallow as 250 km, the sub-system Fe-Ni + C + S becomes relevant and Fe-Ni carbide rather than metallic Fe-Ni alloy may become the crystalline phase of interest. Our study implies that because the partition coefficients between cohenite and Fe-C-S melts are significantly lower than those between Fe-metal and S-rich liquid, in the presence of cohenite and Fe-C-S melt in the mantle, the mantle budget of Ni, Co, and Pt may be dominated by Fe-C-S liquid. W, Re, and Os will also be slightly enriched in C-rich Fe-Ni liquid over cohenite if the metal sub-system of interest is S-free. [1] Chabot et al., GCA 70, 1322-1335, 2006 [2] Chabot et al., GCA 72, 4146-4158, 2008 [3] Chabot et al., Meteorit. Planet. Sci. 42, 1735-1750, 2007 [4] Stewart et al., EPSL 284, 302-309, 2009 [5] Van Orman et al., EPSL 274, 250-257, 2008 [6] Jones, J.H., Malvin, D.J., Metall Mater Trans B 21, 697-706, 1990

FEBio: finite elements for biomechanics.

PubMed

Maas, Steve A; Ellis, Benjamin J; Ateshian, Gerard A; Weiss, Jeffrey A

2012-01-01

In the field of computational biomechanics, investigators have primarily used commercial software that is neither geared toward biological applications nor sufficiently flexible to follow the latest developments in the field. This lack of a tailored software environment has hampered research progress, as well as dissemination of models and results. To address these issues, we developed the FEBio software suite (http://mrl.sci.utah.edu/software/febio), a nonlinear implicit finite element (FE) framework, designed specifically for analysis in computational solid biomechanics. This paper provides an overview of the theoretical basis of FEBio and its main features. FEBio offers modeling scenarios, constitutive models, and boundary conditions, which are relevant to numerous applications in biomechanics. The open-source FEBio software is written in C++, with particular attention to scalar and parallel performance on modern computer architectures. Software verification is a large part of the development and maintenance of FEBio, and to demonstrate the general approach, the description and results of several problems from the FEBio Verification Suite are presented and compared to analytical solutions or results from other established and verified FE codes. An additional simulation is described that illustrates the application of FEBio to a research problem in biomechanics. Together with the pre- and postprocessing software PREVIEW and POSTVIEW, FEBio provides a tailored solution for research and development in computational biomechanics.

Modelling NDE pulse-echo inspection of misorientated planar rough defects using an elastic finite element method

NASA Astrophysics Data System (ADS)

Pettit, J. R.; Walker, A. E.; Lowe, M. J. S.

2015-03-01

Pulse-echo ultrasonic NDE examination of large pressure vessel forgings is a design and construction code requirement in the power generation industry. Such inspections aim to size and characterise potential defects that may have formed during the forging process. Typically these defects have a range of orientations and surface roughnesses which can greatly affect ultrasonic wave scattering behaviour. Ultrasonic modelling techniques can provide insight into defect response and therefore aid in characterisation. However, analytical approaches to solving these scattering problems can become inaccurate, especially when applied to increasingly complex defect geometries. To overcome these limitations a elastic Finite Element (FE) method has been developed to simulate pulse-echo inspections of embedded planar defects. The FE model comprises a significantly reduced spatial domain allowing for a Monte-Carlo based approach to consider multiple realisations of defect orientation and surface roughness. The results confirm that defects aligned perpendicular to the path of beam propagation attenuate ultrasonic signals according to the level of surface roughness. However, for defects orientated away from this plane, surface roughness can increase the magnitude of the scattered component propagating back along the path of the incident beam. This study therefore highlights instances where defect roughness increases the magnitude of ultrasonic scattered signals, as opposed to attenuation which is more often assumed.

PHOTOIONIZATION IN THE SOLAR WIND

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

Landi, E.; Lepri, S. T., E-mail: elandi@umich.edu

2015-10-20

In this work we investigate the effects of photoionization on the charge state composition of the solar wind. Using measured solar EUV and X-ray irradiance, the Michigan Ionization Code and a model for the fast and slow solar wind, we calculate the evolution of the charge state distribution of He, C, N, O, Ne, Mg, Si, S, and Fe with and without including photoionization for both types of wind. We find that the solar radiation has significant effects on the charge state distribution of C, N, and O, causing the ionization levels of these elements to be higher than withoutmore » photoionization; differences are largest for oxygen. The ions commonly observed for elements heavier than O are much less affected, except in ICMEs where Fe ions more ionized than 16+ can also be affected by the solar radiation. We also show that the commonly used O{sup 7+}/O{sup 6+} density ratio is the most sensitive to photoionization; this sensitivity also causes the value of this ratio to depend on the phase of the solar cycle. We show that the O{sup 7+}/O{sup 6+} ratio needs to be used with caution for solar wind classification and coronal temperature estimates, and recommend the C{sup 6+}/C{sup 4+} ratio for these purposes.« less

Distribution and speciation of trace elements in iron and manganese oxide cave deposits

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

Frierdich, Andrew J.; Catalano, Jeffrey G.

2012-10-24

Fe and Mn oxide minerals control the distribution and speciation of heavy metals and trace elements in soils and aquatic systems through chemical mechanisms involving adsorption, incorporation, and electron transfer. The Pautler Cave System in Southwest Illinois, an analog to other temperate carbonate-hosted karst systems, contains Fe and Mn oxide minerals that form in multiple depositional environments and have high concentrations of associated trace elements. Synchrotron-based micro-scanning X-ray fluorescence ({mu}-SXRF) shows unique spatial distributions of Fe, Mn, and trace elements in mineral samples. Profile maps of Mn oxide cave stream pebble coatings show Fe- and As-rich laminations, indicating dynamic redoxmore » conditions in the cave stream. {mu}-SXRF maps demonstrate that Ni, Cu, and Zn correlate primarily with Mn whereas As correlates with both Mn and Fe; As is more enriched in the Fe phase. Zn is concentrated in the periphery of Mn oxide stream pebble coatings, and may be an indication of recent anthropogenic surface activity. X-ray absorption fine structure spectroscopy measurements reveal that As(V) occurs as surface complexes on Mn and Fe oxides whereas Zn(II) associated with Mn oxides is adsorbed to the basal planes of phyllomanganates in a tetrahedral coordination. Co(III) and Se(IV) are also observed to be associated with Mn oxides. The observation of Fe, Mn, and trace element banding in Mn oxide cave stream pebble coatings suggests that these materials are sensitive to and document aqueous redox conditions, similar to ferromanganese nodules in soils and in marine and freshwater sediments. Furthermore, speciation and distribution measurements indicate that these minerals scavenge trace elements and limit the transport of micronutrients and contaminants in karst aquifer systems while also potentially recording changes in anthropogenic surface activity and land-use.« less

Analytical validation of an explicit finite element model of a rolling element bearing with a localised line spall

NASA Astrophysics Data System (ADS)

Singh, Sarabjeet; Howard, Carl Q.; Hansen, Colin H.; Köpke, Uwe G.

2018-03-01

In this paper, numerically modelled vibration response of a rolling element bearing with a localised outer raceway line spall is presented. The results were obtained from a finite element (FE) model of the defective bearing solved using an explicit dynamics FE software package, LS-DYNA. Time domain vibration signals of the bearing obtained directly from the FE modelling were processed further to estimate time-frequency and frequency domain results, such as spectrogram and power spectrum, using standard signal processing techniques pertinent to the vibration-based monitoring of rolling element bearings. A logical approach to analyses of the numerically modelled results was developed with an aim to presenting the analytical validation of the modelled results. While the time and frequency domain analyses of the results show that the FE model generates accurate bearing kinematics and defect frequencies, the time-frequency analysis highlights the simulation of distinct low- and high-frequency characteristic vibration signals associated with the unloading and reloading of the rolling elements as they move in and out of the defect, respectively. Favourable agreement of the numerical and analytical results demonstrates the validation of the results from the explicit FE modelling of the bearing.

The influence of carbon, sulfur, and silicon on trace element partitioning in iron alloys

NASA Astrophysics Data System (ADS)

Han, J.; Van Orman, J. A.; Crispin, K. L.; Ash, R. D.

2014-12-01

Non-metallic light elements are important constituents of planetary cores and have a strong influence on the partitioning behavior of trace elements. Planetary cores may contain a wide range of non-metallic light elements, including H, N, S, P, Si, and C. Under highly reducing conditions, such as those that are thought to have pertained during the formation of Mercury's core, Si and C, in addition to sulfur, may be particularly important constituents. Each of these elements may strongly effect and have a different impact on the partitioning behavior of trace elements but their combined effects on trace element partitioning have not been quantified. We investigated the partitioning behavior of more than 25 siderophile trace elements within the Fe-S-C-Si system with varying concentrations of C, S, and Si. The experiments were performed under pressures varying from 1 atm to 2 GPa and temperatures ranging from 1200˚C to 1450˚C. All experiments produced immiscible liquids, one enriched in Si and C, and the other predominantly FeS. We found some highly siderophile elements including Os, Ru, Ir, and Re are much more enriched in Fe-Si-C phase than in Fe-S phase, whereas other trace elements like V, Co, Ag, Hf, and Pb are enriched in S-rich phase. However, not all the trace elements enriched in Fe-Si-C phase are repelled by sulfur. Elements like Re and Ru could have different partitioning trends if sulfur concentration in S-rich phase rises. The partitioning behavior of these trace elements could enhance our understanding of the differentiation of Mercury's core under oxygen-poor conditions.

Analysis of grain elements and identification of best genotypes for Fe and P in Afghan wheat landraces

PubMed Central

Kondou, Youichi; Manickavelu, Alagu; Komatsu, Kenji; Arifi, Mujiburahman; Kawashima, Mika; Ishii, Takayoshi; Hattori, Tomohiro; Iwata, Hiroyoshi; Tsujimoto, Hisashi; Ban, Tomohiro; Matsui, Minami

2016-01-01

This study was carried out with the aim of developing the methodology to determine elemental composition in wheat and identify the best germplasm for further research. Orphan and genetically diverse Afghan wheat landraces were chosen and EDXRF was used to measure the content of some of the elements to establish elemental composition in grains of 266 landraces using 10 reference lines. Four elements, K, Mg, P, and Fe, were measured by standardizing sample preparation. The results of hierarchical cluster analysis using elemental composition data sets indicated that the Fe content has an opposite pattern to the other elements, especially that of K. By systematic analysis the best wheat germplasms for P content and Fe content were identified. In order to compare the sensitivity of EDXRF, the ICP method was also used and the similar results obtained confirmed the EDXRF methodology. The sampling method for measurement using EDXRF was optimized resulting in high-throughput profiling of elemental composition in wheat grains at low cost. Using this method, we have characterized the Afghan wheat landraces and isolated the best genotypes that have high-elemental content and have the potential to be used in crop improvement. PMID:28163583

Trace element contaminants in mineral fertilizers used in Iran.

PubMed

Latifi, Zahra; Jalali, Mohsen

2018-05-25

The application of mineral fertilizers which have contaminants of trace elements may impose concern regarding the entry and toxic accumulation of these elements in agro-ecosystems. In this study, 57 mineral fertilizers (nitrogen, potassium, phosphate, and compound fertilizers) distributed in Iran were analyzed for their contents of Cd, Co, Cr, Cu, Mn, Ni, Pb, Zn, and Fe. The results revealed that the contents of these trace elements varied considerably depending on the type of the element and the fertilizer. Among these elements, Fe displayed the highest average content, whereas Cd showed the lowest. Generally, the trace element contents in P-containing fertilizers were higher than those in nitrogen and potassium fertilizers. The mean values of trace elements (mg kg -1 ) in P-containing fertilizers were 4.0 (Cd), 5.5 (Co), 35.7 (Cr), 24.4 (Cu), 272 (Mn), 14.3 (Ni), 6.0 (Pb), 226 (Zn), and 2532 (Fe). Comparing trace element contents to limit values set by the German Fertilizer Ordinance showed that the mean contents of potentially toxic trace elements, such as Cd and Pb, were lower than their limit values in all groups of fertilizers. On the other hand, while a number of fertilizers contained a high content of some essential trace elements, particularly Fe, they were not labeled as such.

Scanning Electron Microscope-Cathodoluminescence Analysis of Rare-Earth Elements in Magnets.

PubMed

Imashuku, Susumu; Wagatsuma, Kazuaki; Kawai, Jun

2016-02-01

Scanning electron microscope-cathodoluminescence (SEM-CL) analysis was performed for neodymium-iron-boron (NdFeB) and samarium-cobalt (Sm-Co) magnets to analyze the rare-earth elements present in the magnets. We examined the advantages of SEM-CL analysis over conventional analytical methods such as SEM-energy-dispersive X-ray (EDX) spectroscopy and SEM-wavelength-dispersive X-ray (WDX) spectroscopy for elemental analysis of rare-earth elements in NdFeB magnets. Luminescence spectra of chloride compounds of elements in the magnets were measured by the SEM-CL method. Chloride compounds were obtained by the dropwise addition of hydrochloric acid on the magnets followed by drying in vacuum. Neodymium, praseodymium, terbium, and dysprosium were separately detected in the NdFeB magnets, and samarium was detected in the Sm-Co magnet by the SEM-CL method. In contrast, it was difficult to distinguish terbium and dysprosium in the NdFeB magnet with a dysprosium concentration of 1.05 wt% by conventional SEM-EDX analysis. Terbium with a concentration of 0.02 wt% in an NdFeB magnet was detected by SEM-CL analysis, but not by conventional SEM-WDX analysis. SEM-CL analysis is advantageous over conventional SEM-EDX and SEM-WDX analyses for detecting trace rare-earth elements in NdFeB magnets, particularly dysprosium and terbium.

A Dynamic Finite Element Method for Simulating the Physics of Faults Systems

NASA Astrophysics Data System (ADS)

Saez, E.; Mora, P.; Gross, L.; Weatherley, D.

2004-12-01

We introduce a dynamic Finite Element method using a novel high level scripting language to describe the physical equations, boundary conditions and time integration scheme. The library we use is the parallel Finley library: a finite element kernel library, designed for solving large-scale problems. It is incorporated as a differential equation solver into a more general library called escript, based on the scripting language Python. This library has been developed to facilitate the rapid development of 3D parallel codes, and is optimised for the Australian Computational Earth Systems Simulator Major National Research Facility (ACcESS MNRF) supercomputer, a 208 processor SGI Altix with a peak performance of 1.1 TFlops. Using the scripting approach we obtain a parallel FE code able to take advantage of the computational efficiency of the Altix 3700. We consider faults as material discontinuities (the displacement, velocity, and acceleration fields are discontinuous at the fault), with elastic behavior. The stress continuity at the fault is achieved naturally through the expression of the fault interactions in the weak formulation. The elasticity problem is solved explicitly in time, using the Saint Verlat scheme. Finally, we specify a suitable frictional constitutive relation and numerical scheme to simulate fault behaviour. Our model is based on previous work on modelling fault friction and multi-fault systems using lattice solid-like models. We adapt the 2D model for simulating the dynamics of parallel fault systems described to the Finite-Element method. The approach uses a frictional relation along faults that is slip and slip-rate dependent, and the numerical integration approach introduced by Mora and Place in the lattice solid model. In order to illustrate the new Finite Element model, single and multi-fault simulation examples are presented.

Experiments on Lunar Core Composition: Phase Equilibrium Analysis of A Multi-Element (Fe-Ni-S-C) System

NASA Technical Reports Server (NTRS)

Go, B. M.; Righter, K.; Danielson, L.; Pando, K.

2015-01-01

Previous geochemical and geophysical experiments have proposed the presence of a small, metallic lunar core, but its composition is still being investigated. Knowledge of core composition can have a significant effect on understanding the thermal history of the Moon, the conditions surrounding the liquid-solid or liquid-liquid field, and siderophile element partitioning between mantle and core. However, experiments on complex bulk core compositions are very limited. One limitation comes from numerous studies that have only considered two or three element systems such as Fe-S or Fe-C, which do not supply a comprehensive understanding for complex systems such as Fe-Ni-S-Si-C. Recent geophysical data suggests the presence of up to 6% lighter elements. Reassessments of Apollo seismological analyses and samples have also shown the need to acquire more data for a broader range of pressures, temperatures, and compositions. This study considers a complex multi-element system (Fe-Ni-S-C) for a relevant pressure and temperature range to the Moon's core conditions.

Chemical Compositions of Kinematically Selected Outer Halo Stars

NASA Astrophysics Data System (ADS)

Zhang, Lan; Ishigaki, Miho; Aoki, Wako; Zhao, Gang; Chiba, Masashi

2009-12-01

Chemical abundances of 26 metal-poor dwarfs and giants are determined from high-resolution and high signal-to-noise ratio spectra obtained with the Subaru/High Dispersion Spectrograph. The sample is selected so that most of the objects have outer-halo kinematics. Self-consistent atmospheric parameters were determined by an iterative procedure based on spectroscopic analysis. Abundances of 13 elements, including α-elements (Mg, Si, Ca, Ti), odd-Z light elements (Na, Sc), iron-peak elements (Cr, Mn, Fe, Ni, Zn), and neutron-capture elements (Y, Ba), are determined by two independent data reduction and local thermodynamic equillibrium analysis procedures, confirming the consistency of the stellar parameters and abundances results. We find a decreasing trend of [α/Fe] with increasing [Fe/H] for the range of -3.5< [Fe/H] <-1, as found by Stephens & Boesgaard. [Zn/Fe] values of most objects in our sample are slightly lower than the bulk of halo stars previously studied. These results are discussed as possible chemical properties of the outer halo in the Galaxy. Based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

Trace Element Determination and Cardioprotection of Terminalia pallida Fruit Ethanolic Extract in Isoproterenol Induced Myocardial Infarcted Rats by ICP-MS.

PubMed

Althaf Hussain, Shaik; Kareem, Mohammed Abdul; Rasool, Shaik Nayab; Al Omar, Suliman Yousef; Saleh, Alwasel; Al-Fwuaires, Manal Abdulrahman; Daddam, Jayasimha Rayalu; Devi, Kodidhela Lakshmi

2018-01-01

The trace elements and minerals in Terminalia pallida fruit ethanolic extract (TpFE) were determined by the instrument inductively coupled plasma-mass spectrometry (ICP-MS), and the cardioprotection of TpFE against isoproterenol (ISO)-administered rats was studied. Rats were pretreated with TpFE (100, 300, and 500 mg/kg bw) for 30 days, with concurrent administration of ISO (85 mg/kg bw) for two consecutive days. The levels of trace elements and minerals in TpFE were below the permitted limits of World Health Organization standards. ISO administration significantly increased the heart weight and cardiac marker enzymes in serum, xanthine oxidase, sodium, and calcium in the heart, whereas significantly decreased body weight, reduced glutathione, glutathione-S-transferase, superoxide dismutase, and potassium in the heart. Oral pretreatment of TpFE significantly prevented the ISO-induced alterations. This is the first report that revealed the determination of trace elements and mineral nutrients of TpFE by ICP-MS which plays a principal role in the herbal drug discovery for the treatment of cardiovascular diseases.

[Experimental study and correction of the absorption and enhancement effect between Ti, V and Fe].

PubMed

Tuo, Xian-Guo; Mu, Ke-Liang; Li, Zhe; Wang, Hong-Hui; Luo, Hui; Yang, Jian-Bo

2009-11-01

The absorption and enhancement effects in X-ray fluorescence analysis for Ti, V and Fe elements were studied in the present paper. Three bogus duality systems of Ti-V/Ti-Fe/V-Fe samples were confected and measured by X-ray fluorescence analysis technique using HPGe semiconductor detector, and the relation curve between unitary coefficient (R(K)) of element count rate and element content (W(K)) were obtained after the experiment. Having analyzed the degree of absorption and enhancement effect between every two elements, the authors get the result, and that is the absorption and enhancement effect between Ti and V is relatively distinctness, while it's not so distinctness in Ti-Fe and V-Fe. After that, a mathematics correction method of exponential fitting was used to fit the R(K)-W(K) curve and get a function equation of X-ray fluorescence count rate and content. Three groups of Ti-V duality samples were used to test the fitting method and the relative errors of Ti and V were less than 0.2% as compared to the actual results.

The geochemical cycling of trace elements in a biogenic meromictic lake

NASA Astrophysics Data System (ADS)

Balistrieri, Laurie S.; Murray, James W.; Paul, Barbara

1994-10-01

The geochemical processes affecting the behavior and speciation of As, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, V, and Zn in Hall Lake, Washington, USA, are assessed by examining dissolved and acid soluble particulate profiles of the elements and utilizing results from thermodynamic calculations. The water column of this meromictic lake is highly stratified and contains distinctive oxic, suboxic, and anoxic layers. Changes in the redox state of the water column with depth affect the distribution of all the elements studied. Most noticeable are increases in dissolved Co, Cr, Fe, Mn, Ni, Pb, and Zn concentrations across the oxic-suboxic boundary, increases in dissolved As, Co, Cr, Fe, Mn, and V concentrations with depth in the anoxic layer, significant decreases in dissolved Cu, Ni, Pb, and Zn concentrations in the anoxic region below the sulfide maximum, and large increases in acid soluble particulate concentrations of As, Cr, Cu, Fe, Mo, Ni, Pb, V, and Zn in the anoxic zone below the sulfide maximum. Thermodynamic calculations for the anoxic region indicate that all redox sensitive elements exist in their reduced forms, the primary dissolved forms of Cu, Ni, Pb, and Zn are metal sulfide solution complexes, and solid sulfide phases of Cu, Fe, Mo, and Pb are supersaturated. Calculations using a vertical diffusion and reaction model indicate that the oxidation rate constant for Mn(II) in Hall Lake is estimated to be 0.006 d -1 and is at the lower end of the range of microbial oxidation rates observed in other natural systems. The main geochemical processes influencing the distribution and speciation of trace elements in Hall Lake appear to be transformations of dissolved elements between their oxidation states (As, Cr, Cu, Fe, Mn, V), cocycling of trace elements with Mn and Fe (As, Co, Cr, Cu, Mo, Ni, Pb, V, Zn), formation of soluble metal sulfide complexes (Co, Cu, Ni, Pb, Zn), sorption (As, Co, Cr, Ni, V), and precipitation (Cu, Fe, Mn, Mo, Pb, Zn).

The geochemical cycling of trace elements in a biogenic meromictic lake

USGS Publications Warehouse

Balistrieri, L.S.; Murray, J.W.; Paul, B.

1994-01-01

The geochemical processes affecting the behavior and speciation of As, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, V, and Zn in Hall Lake, Washington, USA, are assessed by examining dissolved and acid soluble particulate profiles of the elements and utilizing results from thermodynamic calculations. The water column of this meromictic lake is highly stratified and contains distinctive oxic, suboxic, and anoxic layers. Changes in the redox state of the water column with depth affect the distribution of all the elements studied. Most noticeable are increases in dissolved Co, Cr, Fe, Mn, Ni, Pb, and Zn concentrations across the oxic-suboxic boundary, increases in dissolved As, Co, Cr, Fe, Mn, and V concentrations with depth in the anoxic layer, significant decreases in dissolved Cu, Ni, Pb, and Zn concentrations in the anoxic region below the sulfide maximum, and large increases in acid soluble particulate concentrations of As, Cr, Cu, Fe, Mo, Ni, Pb, V, and Zn in the anoxic zone below the sulfide maximum. Thermodynamic calculations for the anoxic region indicate that all redox sensitive elements exist in their reduced forms, the primary dissolved forms of Cu, Ni, Pb, and Zn are metal sulfide solution complexes, and solid sulfide phases of Cu, Fe, Mo, and Pb are supersaturated. Calculations using a vertical diffusion and reaction model indicate that the oxidation rate constant for Mn(II) in Hall Lake is estimated to be 0.006 d-1 and is at the lower end of the range of microbial oxidation rates observed in other natural systems. The main geochemical processes influencing the distribution and speciation of trace elements in Hall Lake appear to be transformations of dissolved elements between their oxidation states (As, Cr, Cu, Fe, Mn, V), cocycling of trace elements with Mn and Fe (As, Co, Cr, Cu, Mo, Ni, Pb, V, Zn), formation of soluble metal sulfide complexes (Co, Cu, Ni, Pb, Zn), sorption (As, Co, Cr, Ni, V), and precipitation (Cu, Fe, Mn, Mo, Pb, Zn). ?? 1994.

Interactions of iron with manganese, zinc, chromium, and selenium as related to prophylaxis and treatment of iron deficiency.

PubMed

Bjørklund, Geir; Aaseth, Jan; Skalny, Anatoly V; Suliburska, Joanna; Skalnaya, Margarita G; Nikonorov, Alexandr A; Tinkov, Alexey A

2017-05-01

Iron (Fe) deficiency is considered as the most common nutritional deficiency. Iron deficiency is usually associated with low Fe intake, blood loss, diseases, poor absorption, gastrointestinal parasites, or increased physiological demands as in pregnancy. Nutritional Fe deficiency is usually treated with Fe tablets, sometimes with Fe-containing multimineral tablets. Trace element interactions may have a significant impact on Fe status. Existing data demonstrate a tight interaction between manganese (Mn) and Fe, especially in Fe-deficient state. The influence of Mn on Fe homeostasis may be mediated through its influence on Fe absorption, circulating transporters like transferrin, and regulatory proteins. The existing data demonstrate that the influence of zinc (Zn) on Fe status may be related to their competition for metal transporters. Moreover, Zn may be involved in regulation of hepcidin production. At the same time, human data on the interplay between Fe and Zn especially in terms of Fe-deficiency and supplementation are contradictory, demonstrating both positive and negative influence of Zn on Fe status. Numerous data also demonstrate the possibility of competition between Fe and chromium (Cr) for transferrin binding. At the same time, human data on the interaction between these metals are contradictory. Therefore, while managing hypoferremia and Fe-deficiency anemia, it is recommended to assess the level of other trace elements in parallel with indices of Fe homeostasis. It is supposed that simultaneous correction of trace element status in Fe deficiency may help to decrease possible antagonistic or increase synergistic interactions. Copyright © 2017 Elsevier GmbH. All rights reserved.

Finite element modelling of creep crack growth in 316 stainless and 9Cr-1Mo steels

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

Krishnaswamy, P.; Brust, F.W.

1994-09-01

The failure behavior of steels under sustained and cyclic loads has been addressed. The constitutive behavior of the two steels have been represented by the conventional strain-hardening law and the Murakami-Ohno model for reversed and cyclic loads. The laws have been implemented into the research finite element code FVP. Post processors for FVP to calculate various path independent integral fracture parameters have been written. Compact tension C(T) specimens have been tested under sustained and cyclic loads with both the load point displacement and crack growth monitored during the tests. FE models with extremely refined meshes for the C(T) specimens weremore » prepared and the experiment simulated numerically. Results from this analysis focus on the differences between the various constitutive models as well as the fracture parameters in characterizing the creep crack growth of the two steels.« less

Chemical Composition and Oxidation State of Iron-Containing Aerosol Particles Over West Antarctic Peninsula

NASA Astrophysics Data System (ADS)

Fan, S.; Yu, S.; Lai, B.; Gao, Y.

2017-12-01

Iron is a limiting micronutrient element critical for the marine ecosystem. In the extensive high-nutrient low-chlorophyll (HNLC) regions of the Southern Ocean, the activities of phytoplankton are partly controlled by iron (Fe) from different sources, including atmospheric deposition. Among important properties of atmospheric Fe are the elemental composition and Fe oxidation state of Fe-containing aerosol particles, as these properties affect aerosol Fe solubility. To explore these issues, aerosol samples were collected at Palmer Station in West Antarctic Peninsula. Samples were analyzed by submicron synchrotron-based X-ray fluorescence (XRF) and X-ray absorption near edge structure (XANES) spectroscopy for the Fe oxidation state and elemental composition of aerosol particles. The morphological information of aerosol particles was also observed by the high-resolution fluorescence microscopy, revealing possible sources and formation processes of iron-containing particles. More detailed results will be discussed in this presentation.

Thermal elastic properties of liquid Fe-C at high pressure

NASA Astrophysics Data System (ADS)

Shimoyama, Y.; Terasaki, H. G.; Urakawa, S.; Takubo, Y.; Watanuki, T.; Katayama, Y.; Kondo, T.

2015-12-01

Planetary outer core contains some light elements and these elements affect thermo-elastic parameters of pure iron. The effect of light elements on density and bulk modulus of liquid iron is necessary for estimating of these core compositions. Sound velocity of liquid iron alloys is also important for identifying light elements in the core by comparison with observed seismic data. We have measured sound velocity and density of liquid Fe-C simultaneously at high pressure. High pressure experiments were performed using a DIA-type cubic anvil press (SMAP-180) at BL22XU beamline, SPring-8 synchrotron in Japan. Sound velocity (VP) was measured using pulse-echo overlapping method (Higo et al., 2009). Density (ρ) was measured using X-ray absorption method (Katayama et al., 1993). We measured velocity and density of liquid Fe-C between 1.1-5.8 GPa and 1480-1700 K. Obtained density and velocity of Fe-C was found to increase with pressure. This study shows the VP of liquid Fe-C decreased with increasing temperature. Previous study of liquid Fe-S shows little change with increasing temperature at all pressure conditions (Nishida et al., 2013, Jing et al., 2014). We fit the relationship between VP and pressure using Murnaghan's equation of state. We obtained KS0 = 102.5(1.2) GPa, K'S = 5.2(0.4) at 1700 K. Comparison of the present data with previous study, KS is similar to liquid Fe but liquid Fe-S is small. We compared the relation between density and sound velocity of liquid Fe-C. We have found that the behavior of liquid Fe-C is similar to that of liquid Fe in the Birch's plot. The effect of carbon on liquid Fe is small on Birch's plot.

Process for synthesizing compounds from elemental powders and product

DOEpatents

Rabin, B.H.; Wright, R.N.

1993-12-14

A process for synthesizing intermetallic compounds from elemental powders is described. The elemental powders are initially combined in a ratio which approximates the stoichiometric composition of the intermetallic compound. The mixed powders are then formed into a compact which is heat treated at a controlled rate of heating such that an exothermic reaction between the elements is initiated. The heat treatment may be performed under controlled conditions ranging from a vacuum (pressureless sintering) to compression (hot pressing) to produce a desired densification of the intermetallic compound. In a preferred form of the invention, elemental powders of Fe and Al are combined to form aluminide compounds of Fe[sub 3] Al and FeAl. 25 figures.

Process for synthesizing compounds from elemental powders and product

DOEpatents

Rabin, Barry H.; Wright, Richard N.

1993-01-01

A process for synthesizing intermetallic compounds from elemental powders. The elemental powders are initially combined in a ratio which approximates the stoichiometric composition of the intermetallic compound. The mixed powders are then formed into a compact which is heat treated at a controlled rate of heating such that an exothermic reaction between the elements is initiated. The heat treatment may be performed under controlled conditions ranging from a vacuum (pressureless sintering) to compression (hot pressing) to produce a desired densification of the intermetallic compound. In a preferred form of the invention, elemental powders of Fe and Al are combined to form aluminide compounds of Fe.sub.3 Al and FeAl.

A proposal of monitoring and forecasting system for crustal activity in and around Japan using a large-scale high-fidelity finite element simulation codes

NASA Astrophysics Data System (ADS)

Hori, T.; Ichimura, T.

2015-12-01

Here we propose a system for monitoring and forecasting of crustal activity, especially great interplate earthquake generation and its preparation processes in subduction zone. Basically, we model great earthquake generation as frictional instability on the subjecting plate boundary. So, spatio-temporal variation in slip velocity on the plate interface should be monitored and forecasted. Although, we can obtain continuous dense surface deformation data on land and partly at the sea bottom, the data obtained are not fully utilized for monitoring and forecasting. It is necessary to develop a physics-based data analysis system including (1) a structural model with the 3D geometry of the plate interface and the material property such as elasticity and viscosity, (2) calculation code for crustal deformation and seismic wave propagation using (1), (3) inverse analysis or data assimilation code both for structure and fault slip using (1)&(2). To accomplish this, it is at least necessary to develop highly reliable large-scale simulation code to calculate crustal deformation and seismic wave propagation for 3D heterogeneous structure. Actually, Ichimura et al. (2014, SC14) has developed unstructured FE non-linear seismic wave simulation code, which achieved physics-based urban earthquake simulation enhanced by 10.7 BlnDOF x 30 K time-step. Ichimura et al. (2013, GJI) has developed high fidelity FEM simulation code with mesh generator to calculate crustal deformation in and around Japan with complicated surface topography and subducting plate geometry for 1km mesh. Further, for inverse analyses, Errol et al. (2012, BSSA) has developed waveform inversion code for modeling 3D crustal structure, and Agata et al. (2015, this meeting) has improved the high fidelity FEM code to apply an adjoint method for estimating fault slip and asthenosphere viscosity. Hence, we have large-scale simulation and analysis tools for monitoring. Furthermore, we are developing the methods for forecasting the slip velocity variation on the plate interface. Basic concept is given in Hori et al. (2014, Oceanography) introducing ensemble based sequential data assimilation procedure. Although the prototype described there is for elastic half space model, we will apply it for 3D heterogeneous structure with the high fidelity FE model.

Implications of Responsive Space on the Flight Software Architecture

NASA Technical Reports Server (NTRS)

Wilmot, Jonathan

2006-01-01

The Responsive Space initiative has several implications for flight software that need to be addressed not only within the run-time element, but the development infrastructure and software life-cycle process elements as well. The runtime element must at a minimum support Plug & Play, while the development and process elements need to incorporate methods to quickly generate the needed documentation, code, tests, and all of the artifacts required of flight quality software. Very rapid response times go even further, and imply little or no new software development, requiring instead, using only predeveloped and certified software modules that can be integrated and tested through automated methods. These elements have typically been addressed individually with significant benefits, but it is when they are combined that they can have the greatest impact to Responsive Space. The Flight Software Branch at NASA's Goddard Space Flight Center has been developing the runtime, infrastructure and process elements needed for rapid integration with the Core Flight software System (CFS) architecture. The CFS architecture consists of three main components; the core Flight Executive (cFE), the component catalog, and the Integrated Development Environment (DE). This paper will discuss the design of the components, how they facilitate rapid integration, and lessons learned as the architecture is utilized for an upcoming spacecraft.

Sediment pollution characteristics and in situ control in a deep drinking water reservoir.

PubMed

Zhou, Zizhen; Huang, Tinglin; Li, Yang; Ma, Weixing; Zhou, Shilei; Long, Shenghai

2017-02-01

Sediment pollution characteristics, in situ sediment release potential, and in situ inhibition of sediment release were investigated in a drinking water reservoir. Results showed that organic carbon (OC), total nitrogen (TN), and total phosphorus (TP) in sediments increased from the reservoir mouth to the main reservoir. Fraction analysis indicated that nitrogen in ion exchangeable form and NaOH-extractable P (Fe/Al-P) accounted for 43% and 26% of TN and TP in sediments of the main reservoir. The Risk Assessment Code for metal elements showed that Fe and Mn posed high to very high risk. The results of the in situ reactor experiment in the main reservoir showed the same trends as those observed in the natural state of the reservoir in 2011 and 2012; the maximum concentrations of total OC, TN, TP, Fe, and Mn reached 4.42mg/L, 3.33mg/L, 0.22mg/L, 2.56mg/L, and 0.61mg/L, respectively. An in situ sediment release inhibition technology, the water-lifting aerator, was utilized in the reservoir. The results of operating the water-lifting aerator indicated that sediment release was successfully inhibited and that OC, TN, TP, Fe, and Mn in surface sediment could be reduced by 13.25%, 15.23%, 14.10%, 5.32%, and 3.94%, respectively. Copyright © 2016. Published by Elsevier B.V.

A finite element head and neck model as a supportive tool for deformable image registration.

PubMed

Kim, Jihun; Saitou, Kazuhiro; Matuszak, Martha M; Balter, James M

2016-07-01

A finite element (FE) head and neck model was developed as a tool to aid investigations and development of deformable image registration and patient modeling in radiation oncology. Useful aspects of a FE model for these purposes include ability to produce realistic deformations (similar to those seen in patients over the course of treatment) and a rational means of generating new configurations, e.g., via the application of force and/or displacement boundary conditions. The model was constructed based on a cone-beam computed tomography image of a head and neck cancer patient. The three-node triangular surface meshes created for the bony elements (skull, mandible, and cervical spine) and joint elements were integrated into a skeletal system and combined with the exterior surface. Nodes were additionally created inside the surface structures which were composed of the three-node triangular surface meshes, so that four-node tetrahedral FE elements were created over the whole region of the model. The bony elements were modeled as a homogeneous linear elastic material connected by intervertebral disks. The surrounding tissues were modeled as a homogeneous linear elastic material. Under force or displacement boundary conditions, FE analysis on the model calculates approximate solutions of the displacement vector field. A FE head and neck model was constructed that skull, mandible, and cervical vertebrae were mechanically connected by disks. The developed FE model is capable of generating realistic deformations that are strain-free for the bony elements and of creating new configurations of the skeletal system with the surrounding tissues reasonably deformed. The FE model can generate realistic deformations for skeletal elements. In addition, the model provides a way of evaluating the accuracy of image alignment methods by producing a ground truth deformation and correspondingly simulated images. The ability to combine force and displacement conditions provides flexibility for simulating realistic anatomic configurations.

The iron-nickel-phosphorus system: Effects on the distribution of trace elements during the evolution of iron meteorites

NASA Astrophysics Data System (ADS)

Corrigan, Catherine M.; Chabot, Nancy L.; McCoy, Timothy J.; McDonough, William F.; Watson, Heather C.; Saslow, Sarah A.; Ash, Richard D.

2009-05-01

To better understand the partitioning behavior of elements during the formation and evolution of iron meteorites, two sets of experiments were conducted at 1 atm in the Fe-Ni-P system. The first set examined the effect of P on solid metal/liquid metal partitioning behavior of 22 elements, while the other set explored the effect of the crystal structures of body-centered cubic (α)- and face-centered cubic (γ)-solid Fe alloys on partitioning behavior. Overall, the effect of P on the partition coefficients for the majority of the elements was minimal. As, Au, Ga, Ge, Ir, Os, Pt, Re, and Sb showed slightly increasing partition coefficients with increasing P-content of the metallic liquid. Co, Cu, Pd, and Sn showed constant partition coefficients. Rh, Ru, W, and Mo showed phosphorophile (P-loving) tendencies. Parameterization models were applied to solid metal/liquid metal results for 12 elements. As, Au, Pt, and Re failed to match previous parameterization models, requiring the determination of separate parameters for the Fe-Ni-S and Fe-Ni-P systems. Experiments with coexisting α and γ Fe alloy solids produced partitioning ratios close to unity, indicating that an α versus γ Fe alloy crystal structure has only a minor influence on the partitioning behaviors of the trace element studied. A simple relationship between an element's natural crystal structure and its α/γ partitioning ratio was not observed. If an iron meteorite crystallizes from a single metallic liquid that contains both S and P, the effect of P on the distribution of elements between the crystallizing solids and the residual liquid will be minor in comparison to the effect of S. This indicates that to a first order, fractional crystallization models of the Fe-Ni-S-P system that do not take into account P are appropriate for interpreting the evolution of iron meteorites if the effects of S are appropriately included in the effort.

Concentrations of trace elements in American alligators (Alligator mississippiensis) from Florida, USA.

PubMed

Horai, Sawako; Itai, Takaaki; Noguchi, Takako; Yasuda, Yusuke; Adachi, Haruki; Hyobu, Yuika; Riyadi, Adi S; Boggs, Ashley S P; Lowers, Russell; Guillette, Louis J; Tanabe, Shinsuke

2014-08-01

Concentrations of 28 trace elements (Li, Mg, Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Mo, Ag, Cd, In, Sn, Sb, Cs, Tl, Hg, Pb, and Bi) in the livers of juvenile and adult American alligators inhabiting two central Florida lakes, Lake Apopka (LA), and Lake Woodruff National Wildlife Refuge (LW) and one lagoon population located in Merritt Island National Wildlife Refuge (MINWR; NASA), were determined. In juveniles from MINWR, concentrations of nine elements (Li, Fe, Ni, Sr, In, Sb, Hg, Pb and Bi) were significantly higher, whereas six elements (V, Fe, As, Sr, Hg and Bi) were elevated in adults (p<0.05) obtained from MINWR. Significant enrichment of some trace elements in adults, relative to juveniles, was observed at all three sampling areas. Specifically, Fe, Pb and Hg were significantly elevated in adults when compared to juveniles, suggesting age-dependent accumulation of these elements. Further, As, Se and Sn showed the same trend but only in animals collected from MINWR. Mean Fe concentrations in the livers of adults from LA, LW and MINWR were 1770 μg g(-1) DW, 3690 μg g(-1) DW and 5250 μg g(-1) DW, respectively. More than half of the adult specimens from LW and MINWR exhibited elevated hepatic Fe concentrations that exceed the threshold value for toxic effects in donkey, red deer and human. These results prompted us to express our concern on possible exposure and health effects in American alligators by some trace elements derived from NASA activities. Copyright © 2014 Elsevier Ltd. All rights reserved.

Ab initio study of Fe{sub 2}MnZ (Al, Si, Ge) Heusler alloy using GGA approximation

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

Jain, Vivek Kumar, E-mail: vivek.jain129@gmail.com; Jain, Vishal, E-mail: vivek.jain129@gmail.com; Lakshmi, N., E-mail: vivek.jain129@gmail.com

Density functional theory based on FP-LAPW method used to investigate the electronic structure of Fe{sub 2}MnZ, shows that the total spin magnetic moment shows a trend consistent with the Slater–Pauling curve. The Fe and Mn magnetic moment depend on choice of Z element although the magnetic moment of Z element is negative and less than 0.1 μ{sub B}. Spin polarization calculations evidence 100% spin polarization for Fe{sub 2}MnSi. Fe{sub 2}MnAl and Fe{sub 2}MnGe show metallic behavior with 93%, 98% spin polarization.

Fundamental Parameters of Nearby Young Stars

NASA Astrophysics Data System (ADS)

McCarthy, Kyle; Wilhelm, R. J.

2013-06-01

We present high resolution (R ~ 60,000) spectroscopic data of F and G members of the nearby, young associations AB Doradus and β Pictoris obtained with the Cross-Dispersed Echelle Spectrograph on the 2.7 meter telescope at the McDonald Observatory. Effective temperatures, log(g), [Fe/H], and microturbulent velocities are first estimated using the TGVIT code, then finely tuned using MOOG. Equivalent width (EW) measurements were made using TAME alongside a self-produced IDL routine to constrain EW accuracy and improve computed fundamental parameters. MOOG is also used to derive the chemical abundance of several elements including Mn which is known to be over abundant in planet hosting stars. Vsin(i) are also computed using a χ2 analysis of our observed data to Atlas9 model atmospheres passed through the SPECTRUM spectral synthesis code on lines which do not depend strongly on surface gravity. Due to the limited number of Fe II lines which govern the surface gravity fit in both TGVIT and MOOG, we implement another χ2 analysis of strongly log(g) dependent lines to ensure the values are correct. Coupling the surface gravities and temperatures derived in this study with the luminosities found in the Tycho-2 catalog, we estimate masses for each star and compare these masses to several evolutionary models to begin the process of constraining pre-main sequence evolutionary models.

Lattice stability and thermal properties of Fe2VAl and Fe2TiSn Heusler compounds

NASA Astrophysics Data System (ADS)

Shastri, Shivprasad S.; Pandey, Sudhir K.

2018-04-01

Fe2VAl and Fe2TiSn are two full-Heusler compounds with non-magnetic ground states. They have application as potential thermoelectric materials. Along with first-principles electronic structure calculations, phonon calculation is one of the important tools in condensed matter physics and material science. Phonon calculations are important in understanding mechanical properties, thermal properties and phase transitions of periodic solids. A combination of electronic structure code and phonon calculation code - phonopy is employed in this work. The vibrational spectra, phonon DOS and thermal properties are studied for these two Heusler compounds. Two compounds are found to be dynamically stable with absence of negative frequencies (energy) in the phonon band structure.

Minor element distribution in iron disulfides in coal: a geochemical review

USGS Publications Warehouse

Kolker, Allan

2012-01-01

Electron beam microanalysis of coal samples in U.S. Geological Survey (USGS) labs confirms that As is the most abundant minor constituent in Fe disulfides in coal and that Se, Ni, and other minor constituents are present less commonly and at lower concentrations than those for As. In nearly all cases, Hg occurs in Fe disulfides in coal at concentrations below detection by electron beam instruments. Its presence is shown by laser ablation ICP-MS, by selective leaching studies of bulk coal, and by correlation with Fe disulfide proxies such as total Fe and pyritic sulfur. Multiple generations of Fe disulfides are present in coal. These commonly show grain-to-grain and within-grain minor- or trace element compositional variation that is a function of the early diagenetic, coalification, and post-coalification history of the coal. Framboidal pyrite is almost always the earliest Fe disulfide generation, as shown by overgrowths of later Fe disulfides which may include pyrite or marcasite. Cleat- (or vein) pyrite (or marcasite) is typically the latest Fe disulfide generation, as shown by cross-cutting relations. Cleat pyrite forms by fluid migration within a coal basin and consequently may be enriched in elements such as As by deposition from compaction-driven fluids, metal enriched basinal brines or hydrothermal fluids. In some cases, framboidal pyrite shows preferential Ni enrichment with respect to co-occurring pyrite forms. This is consistent with bacterial complexing of metals in anoxic sediments and derivation of framboidal pyrite from greigite (Fe3S4), an Fe monosulfide precursor to framboidal pyrite having the thio-spinel structure which accommodates transition metals. Elements such as As, Se, and Sb substitute for S in the pyrite structure whereas metals, including transition metals, Hg and Pb, are thought to substitute for Fe. Understanding the distribution of minor and trace elements in Fe disulfides in coal has important implications for their availability to the environment through coal mining and use, as well as for potential reduction by coal preparation, and for delineating diagenetic compositional changes throughout and after coal formation.

Seasonal differences in trace element concentrations and distribution in Spartina alterniflora root tissue

DOE PAGES

Feng, Huan; Qian, Yu; Cochran, J. Kirk; ...

2018-04-13

This study uses nanometer-scale synchrotron X-ray nanofluorescence to investigate season differences in concentrations and distributions of major (Ca, K, S and P) and trace elements (As, Cr, Cu, Fe and Zn) in the root system of Spartina alterniflora collected from Jamaica Bay, New York, in April and September 2015. The root samples were cross-sectioned at a thickness of 10 μm. Selected areas in the root epidermis and endodermis were mapped with a sampling resolution of 100 and 200 nm, varying with the mapping areas. The results indicate that trace element concentrations in the epidermis and endodermis vary among the elementsmore » measured, possibly because of their different chemical properties or their ability to act as micronutrients for the plants. Elemental concentrations (As, Ca, Cr, Cu, Fe, K, P, S and Zn) within each individual root sample and between the root samples collected during two different seasons are both significantly different (p < 0.01). Furthermore, this study indicates that the nonessential elements (As and Cr) are significantly correlated (p < 0.01) with Fe, with high concentrations in the root epidermis, while others are not, implying that Fe may be a barrier to nonessential element transport in the root system. Hierarchy cluster analysis shows two distinct groups, one including As, Cr and Fe and the other the rest of the elements measured. Factor analysis also indicates that the processes and mechanisms controlling element transport in the root system can be different between the nutrient and nonessential elements.« less

Seasonal differences in trace element concentrations and distribution in Spartina alterniflora root tissue

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

Feng, Huan; Qian, Yu; Cochran, J. Kirk

This study uses nanometer-scale synchrotron X-ray nanofluorescence to investigate season differences in concentrations and distributions of major (Ca, K, S and P) and trace elements (As, Cr, Cu, Fe and Zn) in the root system of Spartina alterniflora collected from Jamaica Bay, New York, in April and September 2015. The root samples were cross-sectioned at a thickness of 10 μm. Selected areas in the root epidermis and endodermis were mapped with a sampling resolution of 100 and 200 nm, varying with the mapping areas. The results indicate that trace element concentrations in the epidermis and endodermis vary among the elementsmore » measured, possibly because of their different chemical properties or their ability to act as micronutrients for the plants. Elemental concentrations (As, Ca, Cr, Cu, Fe, K, P, S and Zn) within each individual root sample and between the root samples collected during two different seasons are both significantly different (p < 0.01). Furthermore, this study indicates that the nonessential elements (As and Cr) are significantly correlated (p < 0.01) with Fe, with high concentrations in the root epidermis, while others are not, implying that Fe may be a barrier to nonessential element transport in the root system. Hierarchy cluster analysis shows two distinct groups, one including As, Cr and Fe and the other the rest of the elements measured. Factor analysis also indicates that the processes and mechanisms controlling element transport in the root system can be different between the nutrient and nonessential elements.« less

Cosmic-ray energy spectra between 10 and several hundred GeV per atomic mass unit for elements from Ar-18 to Ni-28 - Results from HEAO 3

NASA Technical Reports Server (NTRS)

Binns, W. R.; Israel, M. H.; Jones, Michael D.; Kamionkowski, M. P.; Garrard, T. L.

1988-01-01

Results from the Heavy Nuclei experiment on HEAO 3 are used to determine the primary abundances of Ni and Fe. Ni and Fe are found to have nearly constant relative abundances over the interval of 10 to about 500 GeV per amu. Individual secondary elements derived principally from interactions of primary Fe nuclei are shown to display a power-law decrease in relative abundance up to about 150 GeV per amu. Ar/Fe and Ca/Fe ratios of 2.6 + or - 0.7 percent and 8.8 + or - 0.7 percent, respectively, are found, confirming a fractionation of source abundances in which elements with high values of the first ionization potential are depleted relative to those with low first ionization potential.

A novel multi-functional magnetic Fe-Ti-V spinel catalyst for elemental mercury capture and callback from flue gas.

PubMed

Yang, Shijian; Guo, Yongfu; Yan, Naiqiang; Wu, Daqing; He, Hongping; Xie, Jiangkun; Qu, Zan; Yang, Chen; Jia, Jinping

2010-11-28

A novel magnetic Fe-Ti-V spinel catalyst showed an excellent performance for elemental mercury capture at 100 °C, and the formed HgO can be catalytically decomposed by the catalyst at 300 °C to reclaim elemental mercury and regenerate the catalyst.

The Chemical Abundances of Stars in the Halo (CASH) Project. II. A Sample of 14 Extremely Metal-poor Stars

NASA Astrophysics Data System (ADS)

Hollek, Julie K.; Frebel, Anna; Roederer, Ian U.; Sneden, Christopher; Shetrone, Matthew; Beers, Timothy C.; Kang, Sung-ju; Thom, Christopher

2011-11-01

We present a comprehensive abundance analysis of 20 elements for 16 new low-metallicity stars from the Chemical Abundances of Stars in the Halo (CASH) project. The abundances have been derived from both Hobby-Eberly Telescope High Resolution Spectrograph snapshot spectra (R ~15, 000) and corresponding high-resolution (R ~35, 000) Magellan Inamori Kyocera Echelle spectra. The stars span a metallicity range from [Fe/H] from -2.9 to -3.9, including four new stars with [Fe/H] < -3.7. We find four stars to be carbon-enhanced metal-poor (CEMP) stars, confirming the trend of increasing [C/Fe] abundance ratios with decreasing metallicity. Two of these objects can be classified as CEMP-no stars, adding to the growing number of these objects at [Fe/H]< - 3. We also find four neutron-capture-enhanced stars in the sample, one of which has [Eu/Fe] of 0.8 with clear r-process signatures. These pilot sample stars are the most metal-poor ([Fe/H] <~ -3.0) of the brightest stars included in CASH and are used to calibrate a newly developed, automated stellar parameter and abundance determination pipeline. This code will be used for the entire ~500 star CASH snapshot sample. We find that the pipeline results are statistically identical for snapshot spectra when compared to a traditional, manual analysis from a high-resolution spectrum. Based on observations obtained with the Hobby-Eberly Telescope, which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universität München, and Georg-August-Universität Göttingen. Based on observations gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

Formation, Phase, and Elemental Composition of Micro- and Nano-Dimensional Particles of the Fe-Ti System

NASA Astrophysics Data System (ADS)

Dresvyannikov, A. F.; Kolpakov, M. E.

2018-05-01

X-ray fluorescence, X-ray phase analysis, and transmission Mössbauer and NGR spectrometry are used to study the formation, phase, and elemental composition of Fe-Ti particles. The interaction between Fe(III) ions and dispersed titanium in an aqueous solution containing chloride ions and HF is studied. It is shown that the resulting Fe-Ti samples are a set of core-shell microparticles with titanium cores coated with micro- and nanosized α-Fe nucleation centers with the thinness outer layer of iron(III) oxide characterized by a developed surface.

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

Stavrou, Elissaios; Yao, Yansun; Goncharov, Alexander F.

In this study, using in situ synchrotron x-ray diffraction and Raman spectroscopy in concert with first principles calculations we demonstrate the synthesis of stable Xe(Fe ,Fe/Ni) 3 and XeNi 3 compounds at thermodynamic conditions representative of Earth’s core. Surprisingly, in the case of both the Xe-Fe and Xe-Ni systems Fe and Ni become highly electronegative and can act as oxidants. In conclusion, the results indicate the changing chemical properties of elements under extreme conditions by documenting that electropositive at ambient pressure elements could gain electrons and form anions.

Finite element modelling to assess the effect of surface mounted piezoelectric patch size on vibration response of a hybrid beam

NASA Astrophysics Data System (ADS)

Rahman, N.; Alam, M. N.

2018-02-01

Vibration response analysis of a hybrid beam with surface mounted patch piezoelectric layer is presented in this work. A one dimensional finite element (1D-FE) model based on efficient layerwise (zigzag) theory is used for the analysis. The beam element has eight mechanical and a variable number of electrical degrees of freedom. The beams are also modelled in 2D-FE (ABAQUS) using a plane stress piezoelectric quadrilateral element for piezo layers and a plane stress quadrilateral element for the elastic layers of hybrid beams. Results are presented to assess the effect of size of piezoelectric patch layer on the free and forced vibration responses of thin and moderately thick beams under clamped-free and clamped-clamped configurations. The beams are subjected to unit step loading and harmonic loading to obtain the forced vibration responses. The vibration control using in phase actuation potential on piezoelectric patches is also studied. The 1D-FE results are compared with the 2D-FE results.

Drill core major, trace and rare earth element anlayses from wells RN-17B and RN-30, Reykjanes, Iceland

DOE Data Explorer

Andrew Fowler

2015-04-01

Analytical results for X-ray fluorescence (XRF) and inductively coupled plasma mass spectrometry (ICP-MS) measurement of major, trace and rare earth elements in drill core from geothermal wells in Reykjanes, Iceland. Total Fe was analyzed as FeO, therefore is not included under the Fe2O3 column.

Drill cutting and core major, trace and rare earth element anlayses from wells RN-17B and RN-30, Reykjanes, Iceland

DOE Data Explorer

Andrew Fowler

2015-05-01

Analytical results for x-ray fluorescence (XRF) and Inductively Couple Plasma Mass Spectrometry (ICP-MS) measurement of major, trace and rare earth elements in drill cuttings from geothermal wells in Reykjanes, Iceland. Total Fe was analyzed as FeO, therefore is not included under the Fe2O3 column.

Anthropometric dependence of the response of a thorax FE model under high speed loading: validation and real world accident replication.

PubMed

Roth, Sébastien; Torres, Fabien; Feuerstein, Philippe; Thoral-Pierre, Karine

2013-05-01

Finite element analysis is frequently used in several fields such as automotive simulations or biomechanics. It helps researchers and engineers to understand the mechanical behaviour of complex structures. The development of computer science brought the possibility to develop realistic computational models which can behave like physical ones, avoiding the difficulties and costs of experimental tests. In the framework of biomechanics, lots of FE models have been developed in the last few decades, enabling the investigation of the behaviour of the human body submitted to heavy damage such as in road traffic accidents or in ballistic impact. In both cases, the thorax/abdomen/pelvis system is frequently injured. The understanding of the behaviour of this complex system is of extreme importance. In order to explore the dynamic response of this system to impact loading, a finite element model of the human thorax/abdomen/pelvis system has, therefore, been developed including the main organs: heart, lungs, kidneys, liver, spleen, the skeleton (with vertebrae, intervertebral discs, ribs), stomach, intestines, muscles, and skin. The FE model is based on a 3D reconstruction, which has been made from medical records of anonymous patients, who have had medical scans with no relation to the present study. Several scans have been analyzed, and specific attention has been paid to the anthropometry of the reconstructed model, which can be considered as a 50th percentile male model. The biometric parameters and laws have been implemented in the dynamic FE code (Radioss, Altair Hyperworks 11©) used for dynamic simulations. Then the 50th percentile model was validated against experimental data available in the literature, in terms of deflection, force, whose curve must be in experimental corridors. However, for other anthropometries (small male or large male models) question about the validation and results of numerical accident replications can be raised. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Connecting mechanics and bone cell activities in the bone remodeling process: an integrated finite element modeling.

PubMed

Hambli, Ridha

2014-01-01

Bone adaptation occurs as a response to external loadings and involves bone resorption by osteoclasts followed by the formation of new bone by osteoblasts. It is directly triggered by the transduction phase by osteocytes embedded within the bone matrix. The bone remodeling process is governed by the interactions between osteoblasts and osteoclasts through the expression of several autocrine and paracrine factors that control bone cell populations and their relative rate of differentiation and proliferation. A review of the literature shows that despite the progress in bone remodeling simulation using the finite element (FE) method, there is still a lack of predictive models that explicitly consider the interaction between osteoblasts and osteoclasts combined with the mechanical response of bone. The current study attempts to develop an FE model to describe the bone remodeling process, taking into consideration the activities of osteoclasts and osteoblasts. The mechanical behavior of bone is described by taking into account the bone material fatigue damage accumulation and mineralization. A coupled strain-damage stimulus function is proposed, which controls the level of autocrine and paracrine factors. The cellular behavior is based on Komarova et al.'s (2003) dynamic law, which describes the autocrine and paracrine interactions between osteoblasts and osteoclasts and computes cell population dynamics and changes in bone mass at a discrete site of bone remodeling. Therefore, when an external mechanical stress is applied, bone formation and resorption is governed by cells dynamic rather than adaptive elasticity approaches. The proposed FE model has been implemented in the FE code Abaqus (UMAT routine). An example of human proximal femur is investigated using the model developed. The model was able to predict final human proximal femur adaptation similar to the patterns observed in a human proximal femur. The results obtained reveal complex spatio-temporal bone adaptation. The proposed FEM model gives insight into how bone cells adapt their architecture to the mechanical and biological environment.

Finite Element analyses of soil bioengineered slopes

NASA Astrophysics Data System (ADS)

Tamagnini, Roberto; Switala, Barbara Maria; Sudan Acharya, Madhu; Wu, Wei; Graf, Frank; Auer, Michael; te Kamp, Lothar

2014-05-01

Soil Bioengineering methods are not only effective from an economical point of view, but they are also interesting as fully ecological solutions. The presented project is aimed to define a numerical model which includes the impact of vegetation on slope stability, considering both mechanical and hydrological effects. In this project, a constitutive model has been developed that accounts for the multi-phase nature of the soil, namely the partly saturated condition and it also includes the effects of a biological component. The constitutive equation is implemented in the Finite Element (FE) software Comes-Geo with an implicit integration scheme that accounts for the collapse of the soils structure due to wetting. The mathematical formulation of the constitutive equations is introduced by means of thermodynamics and it simulates the growth of the biological system during the time. The numerical code is then applied in the analysis of an ideal rainfall induced landslide. The slope is analyzed for vegetated and non-vegetated conditions. The final results allow to quantitatively assessing the impact of vegetation on slope stability. This allows drawing conclusions and choosing whenever it is worthful to use soil bioengineering methods in slope stabilization instead of traditional approaches. The application of the FE methods show some advantages with respect to the commonly used limit equilibrium analyses, because it can account for the real coupled strain-diffusion nature of the problem. The mechanical strength of roots is in fact influenced by the stress evolution into the slope. Moreover, FE method does not need a pre-definition of any failure surface. FE method can also be used in monitoring the progressive failure of the soil bio-engineered system as it calculates the amount of displacements and strains of the model slope. The preliminary study results show that the formulated equations can be useful for analysis and evaluation of different soil bio-engineering methods of slope stabilization.

A Thermo-Poromechanics Finite Element Model for Predicting Arterial Tissue Fusion

NASA Astrophysics Data System (ADS)

Fankell, Douglas P.

This work provides modeling efforts and supplemental experimental work performed towards the ultimate goal of modeling heat transfer, mass transfer, and deformation occurring in biological tissue, in particular during arterial fusion and cutting. Developing accurate models of these processes accomplishes two goals. First, accurate models would enable engineers to design devices to be safer and less expensive. Second, the mechanisms behind tissue fusion and cutting are widely unknown; models with the ability to accurately predict physical phenomena occurring in the tissue will allow for insight into the underlying mechanisms of the processes. This work presents three aims and the efforts in achieving them, leading to an accurate model of tissue fusion and more broadly the thermo-poromechanics (TPM) occurring within biological tissue. Chapters 1 and 2 provide the motivation for developing accurate TPM models of biological tissue and an overview of previous modeling efforts. In Chapter 3, a coupled thermo-structural finite element (FE) model with the ability to predict arterial cutting is offered. From the work presented in Chapter 3, it became obvious a more detailed model was needed. Chapter 4 meets this need by presenting small strain TPM theory and its implementation in an FE code. The model is then used to simulate thermal tissue fusion. These simulations show the model's promise in predicting the water content and temperature of arterial wall tissue during the fusion process, but it is limited by its small deformation assumptions. Chapters 5-7 attempt to address this limitation by developing and implementing a large deformation TPM FE model. Chapters 5, 6, and 7 present a thermodynamically consistent, large deformation TPM FE model and its ability to simulate tissue fusion. Ultimately, this work provides several methods of simulating arterial tissue fusion and the thermo-poromechanics of biological tissue. It is the first work, to the author's knowledge, to simulate the fully coupled TPM of biological tissue and the first to present a fully coupled large deformation TPM FE model. In doing so, a stepping stone for more advanced modeling of biological tissue has been laid.

[Effect of muscle biofidelity on thoracic impact biomechanical response of a six-year-old child using finite element method].

PubMed

Cui, Shihai; Shan, Leilei; Li, Haiyan; Lu, Wenle; He, Lijuan; Ruan, Shijie

2017-02-01

Finite element(FE) model of thorax with high biofidelity is one of the most important methods to investigate thoracic injury mechanism because of the absence of pediatric cadaver experiments. Based on the validated thorax finite element model, the FE models with equivalent muscles and real geometric muscles were developed respectively, and the effect of muscle biofidelity on thoracic injury was analyzed with reconstructing pediatric cadaver thorax impact experiments. The simulation results showed that the thoracic impact force, the maximum displacement and the maximum von-Mises stress of FE models with equivalent muscles were slightly greater than those from FE models with real geometric muscles, and the maximum principal strains of heart and lung were a little lower. And the correlation coefficient between cadaver corridor and FE model with real muscles was also greater than that between cadaver corridor and FE model with equivalent muscles. As a conclusion, the FE models with real geometric muscles can accurately reflect the biomechanical response of thorax during the impact.

[Analysis of mineral elements in different organs at different harvesting times of Schizonepeta tenuifolia on ICP-AES].

PubMed

Shan, Ming-Qiu; Yu, Sheng; Yu, Li-Xia; Ding, An-Wei

2014-02-01

To study the main storage organ of each mineral element in Schizonepeta tenuifolia, and explain its reasonable harvesting time and medicinal parts in view of mineral elements. The mineral elements of Schizonepeta tenuifolia in different organs at different harvesting times were determined by ICP-AES technique. The mineral elements, K, Ca, Na, P, Mg, Mn, Zn, Cu, Fe, Mo, were determined in the study. The results showed that at different harvesting times, (1) the contents of K, P, Cu in fringe and the contents of Mg, Ca, Na, Fe, Mn, Zn in leaf were highest among different organs. (2) among the macroelements, the contents of K and Ca were highest while the content of Na was lowest; among the microelements, the content of Fe was highest while the content of Mo was lowest. (3) in item, the proportion of K:P was highest while the proportion of Zn: Cu was lowest; in fringe, the proportions of Ca:Mg and Fe:Mn were lowest. (4) within the harvest period, variations of the mineral elements were not obvious. In the stem of Schizonepeta tenuifolia, the contents of every mineral elements were lower than other organs, including leaves and spikes. Considering the mineral elements, the correlations of harvesting time and content change were not remarkable.

Axisymmetric whole pin life modelling of advanced gas-cooled reactor nuclear fuel

NASA Astrophysics Data System (ADS)

Mella, R.; Wenman, M. R.

2013-06-01

Thermo-mechanical contributions to pellet-clad interaction (PCI) in advanced gas-cooled reactors (AGRs) are modelled in the ABAQUS finite element (FE) code. User supplied sub-routines permit the modelling of the non-linear behaviour of AGR fuel through life. Through utilisation of ABAQUS's well-developed pre- and post-processing ability, the behaviour of the axially constrained steel clad fuel was modelled. The 2D axisymmetric model includes thermo-mechanical behaviour of the fuel with time and condition dependent material properties. Pellet cladding gap dynamics and thermal behaviour are also modelled. The model treats heat up as a fully coupled temperature-displacement study. Dwell time and direct power cycling was applied to model the impact of online refuelling, a key feature of the AGR. The model includes the visco-plastic behaviour of the fuel under the stress and irradiation conditions within an AGR core and a non-linear heat transfer model. A multiscale fission gas release model is applied to compute pin pressure; this model is coupled to the PCI gap model through an explicit fission gas inventory code. Whole pin, whole life, models are able to show the impact of the fuel on all segments of cladding including weld end caps and cladding pellet locking mechanisms (unique to AGR fuel). The development of this model in a commercial FE package shows that the development of a potentially verified and future-proof fuel performance code can be created and used. The usability of a FE based fuel performance code would be an enhancement over past codes. Pre- and post-processors have lowered the entry barrier for the development of a fuel performance model to permit the ability to model complicated systems. Typical runtimes for a 5 year axisymmetric model takes less than one hour on a single core workstation. The current model has implemented: Non-linear fuel thermal behaviour, including a complex description of heat flow in the fuel. Coupled with a variety of different FE and finite difference models. Non-linear mechanical behaviour of the fuel and cladding including, fuel creep and swelling and cladding creep and plasticity each with dependencies on a variety of different properties. A fission gas release model which takes inputs from first principles calculations. Explicitly integrated inventory calculations performed in a coupled manner. Freedom to model steady state and transient behaviour using implicit time integration. The whole pin geometry is considered over an entire typical fuel life. The model showed by examination of normal operation and a subsequent transient chosen for software demonstration purposes: ABAQUS may be a sufficiently flexible platform to develop a complete and verified fuel performance code. The importance and effectiveness of the geometry of the fuel spacer pellets was characterised. The fuels performance under normal conditions (high friction no power spikes) would not suggest serious degradation of the cladding in fuel life. Large plastic strains were found when pellet bonding was strong, these would appear at all pellets cladding triple points and all pellet radial crack and cladding interfaces thus showing a possible axial direction to cracks forming from ductility exhaustion.

Analysis of Tire Tractive Performance on Deformable Terrain by Finite Element-Discrete Element Method

NASA Astrophysics Data System (ADS)

Nakashima, Hiroshi; Takatsu, Yuzuru

The goal of this study is to develop a practical and fast simulation tool for soil-tire interaction analysis, where finite element method (FEM) and discrete element method (DEM) are coupled together, and which can be realized on a desktop PC. We have extended our formerly proposed dynamic FE-DE method (FE-DEM) to include practical soil-tire system interaction, where not only the vertical sinkage of a tire, but also the travel of a driven tire was considered. Numerical simulation by FE-DEM is stable, and the relationships between variables, such as load-sinkage and sinkage-travel distance, and the gross tractive effort and running resistance characteristics, are obtained. Moreover, the simulation result is accurate enough to predict the maximum drawbar pull for a given tire, once the appropriate parameter values are provided. Therefore, the developed FE-DEM program can be applied with sufficient accuracy to interaction problems in soil-tire systems.

Improved fabrication of focused single element P(VDF–TrFE) transducer for high frequency ultrasound applications

PubMed Central

Jeong, Jong Seob; Shung, K. Kirk

2013-01-01

We present an improved fabrication technique for the focused single element poly (vinylidene fluoride–trifluoroethylene) P(VDF–TrFE) transducer. In this work, a conductive epoxy for a backing layer was directly bonded to the 25 μm thick P(VDF–TrFE) film and thus made it easy to conform the aperture of the P(VDF–TrFE) transducer. Two prototype focused P(VDF–TrFE) transducers with disk- and ring-type aperture were fabricated and their performance was evaluated using the UBM (Ultrasound Biomicroscopy) system with a wire phantom. All transducers had a spherically focused aperture with a low f-number (focal depth/aperture size = 1). The center frequency of the disk-type P(VDF–TrFE) transducer was 23 MHz and −6 dB bandwidth was 102%. The ring-type P(VDF–TrFE) transducer had 20 MHz center frequency and −6 dB bandwidth of 103%. The measured pulse echo signal had reduced reverberation due to no additional adhesive layer between the P(VDF–TrFE) film and the backing layer. Hence, the proposed method is promising to fabricate a single element transducer using P(VDF–TrFE) film for high frequency applications. PMID:23021238

Sound velocity of iron-light element compounds and the chemical structure of the inner core

NASA Astrophysics Data System (ADS)

Ohtani, E.; Sakamaki, T.; Fukui, H.; Tanaka, R.; Shibazaki, Y.; Kamada, S.; Sakairi, T.; Takahashi, S.; Tsutsui, S.; Baron, A. Q. R.

2016-12-01

The light elements in the core could constrain the conditions of accretion, subsequent magma ocean, and core formation stages of the Earth. There are several studies for sound velocity measurements of the iron-light elements alloys. However, the measurements are not enough to constrain the light element abundance in the core tightly at present due to inter-laboratory inconsistencies using different methods which are originated from the difficulties to make such measurements under the extreme conditions. We measured the sound velocity of iron alloy compounds at high pressure and temperature relevant to the Earth's core using double-sided laser heating of a DAC combined with inelastic X-ray scattering at SPring-8. We measured the compressional velocity of hcp-Fe up to 166 GPa and 3000 K, and derived a clear temperature dependence of the Birch's law for hcp-Fe. We measured the compressional velocity of Fe0.89Si0.11 alloy and Fe3C at high pressure and temperature, and we could not detect temperature dependency in Birch's law in these compounds. Additionally, we measured the sound velocity of Fe3S, Fe0.83Ni0.09Si0.08 alloy, and FeH at high pressure. Combining our new data set which showed remarkable differences from previous data on the sound velocity, we present a model of the chemical structure of the inner core. The outer core composition was also estimated based on partitioning behaviors of these light elements between solid and liquid iron alloys under the core conditions.

Separation of copper, iron, and zinc from complex aqueous solutions for isotopic measurement

USGS Publications Warehouse

Borrok, D.M.; Wanty, R.B.; Ridley, W.I.; Wolf, R.; Lamothe, P.J.; Adams, M.

2007-01-01

The measurement of Cu, Fe, and Zn isotopes in natural samples may provide valuable information about biogeochemical processes in the environment. However, the widespread application of stable Cu, Fe, and Zn isotope chemistry to natural water systems remains limited by our ability to efficiently separate these trace elements from the greater concentrations of matrix elements. In this study, we present a new method for the isolation of Cu, Fe, and Zn from complex aqueous solutions using a single anion-exchange column with hydrochloric acid media. Using this method we are able to quantitatively separate Cu, Fe, and Zn from each other and from matrix elements in a single column elution. Elution of the elements of interest, as well as all other elements, through the anion-exchange column is a function of the speciation of each element in the various concentrations of HCl. We highlight the column chemistry by comparing our observations with published studies that have investigated the speciation of Cu, Fe, and Zn in chloride solutions. The functionality of the column procedure was tested by measuring Cu, Fe, and Zn isotopes in a variety of stream water samples impacted by acid mine drainage. The accuracy and precision of Zn isotopic measurements was tested by doping Zn-free stream water with the Zn isotopic standard. The reproducibility of the entire column separation process and the overall precision of the isotopic measurements were also evaluated. The isotopic results demonstrate that the Cu, Fe, and Zn column separates from the tested stream waters are of sufficient purity to be analyzed directly using a multicollector inductively coupled plasma mass spectrometer (MC-ICP-MS), and that the measurements are fully-reproducible, accurate, and precise. Although limited in scope, these isotopic measurements reveal significant variations in ??65Cu (- 1.41 to + 0.30???), ??56Fe (- 0.56 to + 0.34???), and ??66Zn (0.31 to 0.49???) among samples collected from different abandoned mines within a single watershed. Hence, Cu, Fe, and Zn isotopic measurements may be a powerful tool for fingerprinting specific metal sources and/or examining biogeochemical reactions within fresh water systems.

Siderophile trace element diffusion in Fe-Ni alloys

NASA Astrophysics Data System (ADS)

Watson, Heather C.; Watson, E. Bruce

2003-09-01

Experiments were performed in a piston cylinder apparatus to characterize the diffusion behavior of the siderophile elements, Mo, Cu, Pd, Au, and Re in solid Fe-Ni alloy (90 wt.% Fe, 10 wt.% Ni). All experiments were conducted at 1 GPa and temperatures ranging from 1175 to 1400 °C. Activation energies of all elements fall between 270 kJ/mol (Cu) and 360 kJ/mol (Mo). Mo, Cu, Pd, and Au all show similar diffusivities at the same conditions, but the diffusivity of Re was consistently close to an order of magnitude lower. Initial experiments on other refractory elements (Os, Pt, and Ir) indicate that their diffusivities are close to or slightly lower than that of Re.

Coupling Finite Element and Meshless Local Petrov-Galerkin Methods for Two-Dimensional Potential Problems

NASA Technical Reports Server (NTRS)

Chen, T.; Raju, I. S.

2002-01-01

A coupled finite element (FE) method and meshless local Petrov-Galerkin (MLPG) method for analyzing two-dimensional potential problems is presented in this paper. The analysis domain is subdivided into two regions, a finite element (FE) region and a meshless (MM) region. A single weighted residual form is written for the entire domain. Independent trial and test functions are assumed in the FE and MM regions. A transition region is created between the two regions. The transition region blends the trial and test functions of the FE and MM regions. The trial function blending is achieved using a technique similar to the 'Coons patch' method that is widely used in computer-aided geometric design. The test function blending is achieved by using either FE or MM test functions on the nodes in the transition element. The technique was evaluated by applying the coupled method to two potential problems governed by the Poisson equation. The coupled method passed all the patch test problems and gave accurate solutions for the problems studied.

High Temperature Oxidation of Hot-Dip Aluminized T92 Steels

NASA Astrophysics Data System (ADS)

Abro, Muhammad Ali; Hahn, Junhee; Lee, Dong Bok

2018-03-01

The T92 steel plate was hot-dip aluminized, and oxidized in order to characterize the high-temperature oxidation behavior of hot-dip aluminized T92 steel. The coating consisted of Al-rich topcoat with scattered Al3Fe grains, Al3Fe-rich upper alloy layer with scattered (Al, Al5Fe2, AlFe)-grains, and Al5Fe2-rich lower alloy layer with scattered (Al5Fe2, AlFe)-grains. Oxidation at 800 °C for 20 h formed (α-Al2O3 scale)/(AlFe layer)/(AlFe3 layer)/(α-Fe(Al) layer), while oxidation at 900 °C for 20 h formed (α-Al2O3 scale plus some Fe2O3)/(AlFe layer)/(AlFe3 layer)/(α-Fe(Al) layer) from the surface. During oxidation, outward migration of all substrate elements, inward diffusion of oxygen, and back and forth diffusion of Al occurred according to concentration gradients. Also, diffusion transformed and broadened AlFe and AlFe3 layers dissolved with some oxygen and substrate alloying elements. Hot-dip aluminizing improved the high-temperature oxidation resistance of T92 steel through preferential oxidation of Al at the surface.

High Temperature Oxidation of Hot-Dip Aluminized T92 Steels

NASA Astrophysics Data System (ADS)

Abro, Muhammad Ali; Hahn, Junhee; Lee, Dong Bok

2018-05-01

The T92 steel plate was hot-dip aluminized, and oxidized in order to characterize the high-temperature oxidation behavior of hot-dip aluminized T92 steel. The coating consisted of Al-rich topcoat with scattered Al3Fe grains, Al3Fe-rich upper alloy layer with scattered (Al, Al5Fe2, AlFe)-grains, and Al5Fe2-rich lower alloy layer with scattered (Al5Fe2, AlFe)-grains. Oxidation at 800 °C for 20 h formed (α-Al2O3 scale)/(AlFe layer)/(AlFe3 layer)/(α-Fe(Al) layer), while oxidation at 900 °C for 20 h formed (α-Al2O3 scale plus some Fe2O3)/(AlFe layer)/(AlFe3 layer)/(α-Fe(Al) layer) from the surface. During oxidation, outward migration of all substrate elements, inward diffusion of oxygen, and back and forth diffusion of Al occurred according to concentration gradients. Also, diffusion transformed and broadened AlFe and AlFe3 layers dissolved with some oxygen and substrate alloying elements. Hot-dip aluminizing improved the high-temperature oxidation resistance of T92 steel through preferential oxidation of Al at the surface.

The Abundances of the Fe Group Elements in Three Early B Stars in the Large Magellanic Cloud

NASA Astrophysics Data System (ADS)

Peters, G. J.; Adelman, S. J.

2005-12-01

The photospheric abundances of V, Cr, and Fe have been determined for three sharp-lined early B stars in the Large Magellanic Cloud using FUV spectra obtained from the Far Ultraviolet Spectroscopic Explorer (FUSE) and the Kurucz LTE model atmosphere/spectrum synthesis codes ATLAS9/SYNTHE. The program stars include NGC1818/D1, NGC2004/B15, and NGC2004/B30 (star designations are from Robertson 1974, A&AS, 15, 261). The calculations were carried through with model parameters close to those adopted by Korn et al. (2000, A&A, 353, 655). Values of Teff, log g, ξ T, and v sin I are 25000/4.0/0/30, 20000/3.1/6/25, and 23500/3.3/14/30 for NGC1818/D1, NGC2004/B15, and NGC2004/B30, respectively. The abundances quoted below are in sequence for the latter stars. The vanadium abundances, [V/H], determined from V III λ λ 1150,1152 (UV 2), are -0.6, -0.9, and -0.9 dex. Cr was determined from Cr III λ λ 1118,1136. Values of -0.5, -0.8, and -0.7 dex were found. Uncertainties in the V and Cr abundances are ˜0.3 dex. The Fe abundance is primarily from 7 lines of Fe III (UV 1) in the region λ λ 1122-32. Values are -0.8±0.3, ˜-1.1, and -0.4±0.3. Since there is no evidence for N enhancement in the program stars ([N/H] ˜ -0.9, -1.0, and -0.6 from the N III doublet at 1183,1184 Å) the photospheric abundances have probably not been altered by mixing of processed material from the star's interior and the derived abundances represent pristine values for the two young clusters in the LMC. It should be noted that the N and Fe abundances derived for NGC1818/D1 are about 0.5 dex lower than those determined by Korn et al. from much weaker optical lines. We will discuss possible reasons for the discrepancy. The generally low abundances for the Fe group elements in these young cluster B stars imply that supernova activity has been minimal in the regions of the LMC in which the stars were formed. GJP appreciates support from NASA grant NAG5-13212.

Hyperfine fields of Fe in Nd2Fe14BandSm2Fe17N3

NASA Astrophysics Data System (ADS)

Akai, Hisazumi; Ogura, Masako

2015-03-01

High saturation magnetization of rare-earth magnets originates from Fe and the strong magnetic anisotropy stems from f-states of rare-earth elements such as Nd and Sm. Therefore the hyperfine fields of both Fe and rare-earth provide us with important pieces of information: Fe NMR enable us to detect site dependence of the local magnetic moment and magnetic anisotropy (Fe sites also contribute to the magnetic anisotropy) while rare-earth NQR directly give the information of electric field gradients (EFG) that are related to the shape of the f-electron cloud as well as the EFG produced by ligands. In this study we focus on the hyperfine fields of materials used as permanent magnets, Nd2Fe14BandSm2Fe17N3 from theoretical points of view. The detailed electronic structure together with the hyperfine interactions are discussed on the basis of the first-principles calculation. In particular, the relations between the observed hyperfine fields and the magnetic properties are studies in detail. The effects of doping of those materials by other elements such as Dy and the effects of N adding in Sm2Fe17N3 will be discussed. This work was supported by Elements Strategy Initiative Center for Magnetic Materials Project, the Ministry of Education, Culture, Sports, Science and Technology, Japan.

Melting Experiments in the Fe-FeSi System at High Pressure

NASA Astrophysics Data System (ADS)

Ozawa, H.; Hirose, K.

2013-12-01

The principal light element in the Earth's core must reproduce the density jump at the inner core boundary (ICB). Silicon is thought to be a plausible light element in the core, and the melting phase relations in Fe-FeSi binary system at the ICB pressure are of great importance. Theoretical calculations on the Fe-FeSi binary system suggested that the difference in Si content between the outer core and the inner core would be too small to satisfy the observed density jump at the ICB [Alfè et al., 2002 EPSL], which requires other light elements in addition to silicon. Here we experimentally examined partitioning of silicon between liquid and solid iron up to 97 GPa. High pressure and temperature conditions were generated in a laser-heated diamond-anvil cell. Chemical compositions of co-existing quenched liquid and solid Fe-Si alloys were determined with a field-emission-type electron probe micro-analyzer. We used Fe-Si alloy containing 9 wt% Si as a starting material. Chemical analyses on the recovered samples from 39 and 49 GPa demonstrated the coexistence of quenched Si-depleted liquid and Si-enriched solid. In contrast, silicon partitions preferentially into liquid metal at 97 GPa, suggesting the starting composition (Fe-9wt% Si) lies on the iron-rich part of the eutectic. These results indicate the eutectic composition shifts toward FeSi between 49 and 97 GPa.

Effects of alloying elements (Mn, Co, Al, W, Sn, B, C and S) on biodegradability and in vitro biocompatibility of pure iron.

PubMed

Liu, B; Zheng, Y F

2011-03-01

Pure iron was determined to be a valid candidate material for biodegradable metallic stents in recent animal tests; however, a much faster degradation rate in physiological environments was desired. C, Mn, Si, P, S, B, Cr, Ni, Pb, Mo, Al, Ti, Cu, Co, V and W are common alloying elements in industrial steels, with Cr, Ni, Mo, Cu, Ti, V and Si being acknowledged as beneficial in enhancing the corrosion resistance of iron. The purpose of the present work (using Fe-X binary alloy models) is to explore the effect of the remaining alloying elements (Mn, Co, Al, W, B, C and S) and one detrimental impurity element Sn on the biodegradability and biocompatibility of pure iron by scanning electron microscopy, X-ray diffraction, metallographic observation, tensile testing, microhardness testing, electrochemical testing, static (for 6 months) and dynamic (for 1 month with various dissolved oxygen concentrations) immersion testing, cytotoxicity testing, hemolysis and platelet adhesion testing. The results showed that the addition of all alloying elements except for Sn improved the mechanical properties of iron after rolling. Localized corrosion of Fe-X binary alloys was observed in both static and dynamic immersion tests. Except for the Fe-Mn alloy, which showed a significant decrease in corrosion rate, the other Fe-X binary alloy corrosion rates were close to that of pure iron. It was found that compared with pure iron all Fe-X binary alloys decreased the viability of the L929 cell line, none of experimental alloying elements significantly reduced the viability of vascular smooth muscle cells and all the elements except for Mn increased the viability of the ECV304 cell line. The hemolysis percentage of all Fe-X binary alloy models were less than 5%, and no sign of thrombogenicity was observed. In vitro corrosion and the biological behavior of these Fe-X binary alloys are discussed and a corresponding mechanism of corrosion of Fe-X binary alloys in Hank's solution proposed. As a concluding remark, Co, W, C and S are recommended as alloying elements for biodegradable iron-based biomaterials. Copyright © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Atomic-scale to Meso-scale Simulation Studies of Thermal Ageing and Irradiation Effects in Fe- Cr Alloys

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

Stanley, Eugene; Liu, Li

In this project, we target at three primary objectives: (1) Molecular Dynamics (MD) code development for Fe-Cr alloys, which can be utilized to provide thermodynamic and kinetic properties as inputs in mesoscale Phase Field (PF) simulations; (2) validation and implementation of the MD code to explain thermal ageing and radiation damage; and (3) an integrated modeling platform for MD and PF simulations. These two simulation tools, MD and PF, will ultimately be merged to understand and quantify the kinetics and mechanisms of microstructure and property evolution of Fe-Cr alloys under various thermal and irradiation environments

Modelling NDE pulse-echo inspection of misorientated planar rough defects using an elastic finite element method

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

Pettit, J. R.; Lowe, M. J. S.; Walker, A. E.

2015-03-31

Pulse-echo ultrasonic NDE examination of large pressure vessel forgings is a design and construction code requirement in the power generation industry. Such inspections aim to size and characterise potential defects that may have formed during the forging process. Typically these defects have a range of orientations and surface roughnesses which can greatly affect ultrasonic wave scattering behaviour. Ultrasonic modelling techniques can provide insight into defect response and therefore aid in characterisation. However, analytical approaches to solving these scattering problems can become inaccurate, especially when applied to increasingly complex defect geometries. To overcome these limitations a elastic Finite Element (FE) methodmore » has been developed to simulate pulse-echo inspections of embedded planar defects. The FE model comprises a significantly reduced spatial domain allowing for a Monte-Carlo based approach to consider multiple realisations of defect orientation and surface roughness. The results confirm that defects aligned perpendicular to the path of beam propagation attenuate ultrasonic signals according to the level of surface roughness. However, for defects orientated away from this plane, surface roughness can increase the magnitude of the scattered component propagating back along the path of the incident beam. This study therefore highlights instances where defect roughness increases the magnitude of ultrasonic scattered signals, as opposed to attenuation which is more often assumed.« less

Forming limit diagrams of tubes with initial wall-thickness difference based on different instability criteria

NASA Astrophysics Data System (ADS)

Zhao, Qiwen; Yang, Lianfa; He, Yulin

2018-05-01

The Forming limit diagram (FLD), also known as a forming limit curves (FLC), is generally used in metal forming for predicting forming behavior of metals. The purpose of the study is to clarify the difference among the FLC of tubes with initial wall-thickness difference under tension-compression strain states using finite element (FE) simulation of tube hydroforming (THF) and different instability criteria. Firstly, geometrical models for SUS304 stainless steel tubes with initial wall-thickness differences were built by introducing an index `wall-thickness deviation rate'. Secondly, forced-end hydro-bugling of the tubes was modeled and the forming process was simulated by using the commercial finite element (FE) code ABAQUS/Explicit 6.10. Afterwards, the limiting strains of the material in the hydro-bugling process were calculated based on the simulated resultant data and three instability criteria-strain change criterion, strain rate change criterion and strain path change criterion, respectively. Finally, the FLD for the tubes was established and the effect of wall-thickness deviation rate on the FLD was analyzed and the differences among the FLC based on the three instability criteria were compared. The results showed that the FLC are observed to shift in the major-minor strain coordinate system due to the initial non-uniform wall-thickness; however, no distinct differences among the FLC based on the three instability criteria were observed.

Synthesis of Xenon and Iron-Nickel Intermetallic Compounds at Earth's Core Thermodynamic Conditions

NASA Astrophysics Data System (ADS)

Stavrou, Elissaios; Yao, Yansun; Goncharov, Alexander F.; Lobanov, Sergey S.; Zaug, Joseph M.; Liu, Hanyu; Greenberg, Eran; Prakapenka, Vitali B.

2018-03-01

Using in situ synchrotron x-ray diffraction and Raman spectroscopy in concert with first principles calculations we demonstrate the synthesis of stable Xe (Fe ,Fe /Ni )3 and XeNi3 compounds at thermodynamic conditions representative of Earth's core. Surprisingly, in the case of both the Xe-Fe and Xe-Ni systems Fe and Ni become highly electronegative and can act as oxidants. The results indicate the changing chemical properties of elements under extreme conditions by documenting that electropositive at ambient pressure elements could gain electrons and form anions.

Mass-invariance of the iron enrichment in the hot haloes of massive ellipticals, groups, and clusters of galaxies

NASA Astrophysics Data System (ADS)

Mernier, F.; de Plaa, J.; Werner, N.; Kaastra, J. S.; Raassen, A. J. J.; Gu, L.; Mao, J.; Urdampilleta, I.; Truong, N.; Simionescu, A.

2018-05-01

X-ray measurements find systematically lower Fe abundances in the X-ray emitting haloes pervading groups (kT ≲ 1.7 keV) than in clusters of galaxies. These results have been difficult to reconcile with theoretical predictions. However, models using incomplete atomic data or the assumption of isothermal plasmas may have biased the best fit Fe abundance in groups and giant elliptical galaxies low. In this work, we take advantage of a major update of the atomic code in the spectral fitting package SPEX to re-evaluate the Fe abundance in 43 clusters, groups, and elliptical galaxies (the CHEERS sample) in a self-consistent analysis and within a common radius of 0.1r500. For the first time, we report a remarkably similar average Fe enrichment in all these systems. Unlike previous results, this strongly suggests that metals are synthesised and transported in these haloes with the same average efficiency across two orders of magnitude in total mass. We show that the previous metallicity measurements in low temperature systems were biased low due to incomplete atomic data in the spectral fitting codes. The reasons for such a code-related Fe bias, also implying previously unconsidered biases in the emission measure and temperature structure, are discussed.

Blast and the Consequences on Traumatic Brain Injury-Multiscale Mechanical Modeling of Brain

DTIC Science & Technology

2011-02-17

blast simulation. LS-DYNA as an explicit FE code has been employed to simulate this multi- material fluid –structure interaction problem. The 3-D head...formulation is implemented to model the air-blast simulation. LS-DYNA as an explicit FE code has been employed to simulate this multi-material fluid ...Biomechanics Study of Influencing Parameters for brain under Impact ............................... 12 5.1 The Impact of Cerebrospinal Fluid

In-situ Density and Thermal Expansion Measurements of Fe and Fe-S Alloying Liquids Under Planetary Core Conditions

NASA Astrophysics Data System (ADS)

Jing, Z.; Chantel, J.; Yu, T.; Sakamaki, T.; Wang, Y.

2015-12-01

Liquid iron is likely the dominant constituent in the cores of terrestrial planets and icy satellites such as Earth, Mars, Mercury, the Moon, Ganymede, and Io. Suggested by geophysical and geochemical observations, light elements such as S, C, Si, etc., are likely present in planetary cores. These light elements can significantly reduce the density and melting temperature of the Fe cores, and hence their abundances are crucial to our understanding of the structure and thermal history of planetary cores, as well as the generation of intrinsic magnetic fields. Knowledge on the density of Fe-light element alloying liquids at high pressures is critical to place constraints on the composition of planetary cores. However, density data on liquid Fe-light element alloys at core pressures are very limited in pressure and composition and are sometimes controversial. In this study, we extend the density dataset for Fe-rich liquids by measuring the density of Fe, Fe-10wt%S, Fe-20wt%S, Fe-27wt%S, and FeS liquids using the X-ray absorption technique in a DIA-type multianvil apparatus up to 7 GPa and 2173 K. An ion chamber (1D-detector) and a CCD camera (2D-detector) were used to measure intensities of transmitted monochromatic X-rays through molten samples, with the photon energy optimized at 40 keV. The densities were then determined from the Beer-Lambert law using the mass absorption coefficients, calibrated by solid standards using X-ray diffraction. At each pressure, density measurements were conducted at a range of temperatures above the liquidus of the samples, enabling the determination of thermal expansion. Combined with our previous results on the sound velocity of Fe and Fe-S liquids at high pressures (Jing et al., 2014, Earth Planet. Sci. Lett. 396, 78-87), these data provide tight constraints on the equation of state and thermodynamic properties such as the adiabatic temperature gradient for Fe-S liquids. We will discuss these results with implications to planetary cores.

Diffusion, phase equilibria and partitioning experiments in the Ni-Fe-Ru system

NASA Technical Reports Server (NTRS)

Blum, Joel D.; Wasserburg, G. J.; Hutcheon, I. D.; Beckett, J. R.; Stolper, E. M.

1989-01-01

Results are presented on thin-film diffusion experiments designed to investigate phase equilibria in systems containing high concentrations of Pt-group elements, such as Ni-Fe-Ru-rich systems containing Pt, at temperatures of 1273, 1073, and 873 K. The rate of Ru diffusion in Ni was determined as a function of temperature, and, in addition, the degree of Pt and Ir partitioning between phases in a Ni-Fe-Ru-rich system and of V between phases in a Ni-Fe-O-rich system at 873 were determined. It was found that Pt preferentially partitions into the (gamma)Ni-Fe phase, whereas Ir prefers the (epsilon)Ru-Fe phase. V partitions strongly into Fe oxides relative to (gamma)Ni-Fe. These results have direct application to the origin and thermal history of the alloys rich in Pt-group elements in meteorites.

An Experimental Analog for Metal-Sulfide Partitioning in Acapulcoite-Lodranite Meteorites

NASA Astrophysics Data System (ADS)

Dhaliwal, J. K.; Chabot, N. L.; Ash, R. D.; McCoy, T. J.

2018-05-01

This study builds on prior analyses of highly siderophile element (HSE) abundances in primitive achondrites. We performed melting experiments of naturally occurring FeNi and FeS to examine the effect of sulfur on HSE inter-element partitioning.

Content and Bioaccumulation of Nine Mineral Elements in Ten Mushroom Species of the Genus Boletus

PubMed Central

Wang, Xue-Mei; Zhang, Ji; Li, Tao; Wang, Yuan-Zhong; Liu, Hong-Gao

2015-01-01

Concentrations and bioconcentration potential of nine elements (Ca, Cu, Fe, K, Mg, Mn, Na, P, and Zn) in ten species of wild edible Boletus and the corresponding underlying soils were analyzed. The analyses were performed using inductively coupled plasma atomic emission spectrophotometer. Boletus showed relative abundant contents of P, K, Fe, Mg, Ca, and Na and less of Zn, Cu, and Mn. Caps compared to stalks were enriched in P, K, Cu, Mg, and Zn, while stalks were enriched in Mn. The elements such as P and K were accumulated (BCF > 1), while Ca, Fe, Mg, Mn, and Na were excluded (BCF < 1) in the fruiting bodies. The correlation analysis indicated high correlations between Cu, Mn, Ca, and Fe in the mushrooms as compared to the corresponding soils. Significant correlations were also obtained between Cu-P (r = 0.775), Fe-P (r = 0.728), and Zn-P (r = 0.76) for caps and Cu-Mg (r = 0.721), Fe-Mg (r = 0.719), Zn-Mg (r = 0.824), and Zn-P (r = 0.818) for stalks. The results of this study imply that ability of fungi to accumulate elements from substrate could be influenced by mushroom species and underlying soil substrates. PMID:26146585

Content and Bioaccumulation of Nine Mineral Elements in Ten Mushroom Species of the Genus Boletus.

PubMed

Wang, Xue-Mei; Zhang, Ji; Li, Tao; Wang, Yuan-Zhong; Liu, Hong-Gao

2015-01-01

Concentrations and bioconcentration potential of nine elements (Ca, Cu, Fe, K, Mg, Mn, Na, P, and Zn) in ten species of wild edible Boletus and the corresponding underlying soils were analyzed. The analyses were performed using inductively coupled plasma atomic emission spectrophotometer. Boletus showed relative abundant contents of P, K, Fe, Mg, Ca, and Na and less of Zn, Cu, and Mn. Caps compared to stalks were enriched in P, K, Cu, Mg, and Zn, while stalks were enriched in Mn. The elements such as P and K were accumulated (BCF > 1), while Ca, Fe, Mg, Mn, and Na were excluded (BCF < 1) in the fruiting bodies. The correlation analysis indicated high correlations between Cu, Mn, Ca, and Fe in the mushrooms as compared to the corresponding soils. Significant correlations were also obtained between Cu-P (r = 0.775), Fe-P (r = 0.728), and Zn-P (r = 0.76) for caps and Cu-Mg (r = 0.721), Fe-Mg (r = 0.719), Zn-Mg (r = 0.824), and Zn-P (r = 0.818) for stalks. The results of this study imply that ability of fungi to accumulate elements from substrate could be influenced by mushroom species and underlying soil substrates.

Observing the metal-poor solar neighbourhood: a comparison of galactic chemical evolution predictions*†

NASA Astrophysics Data System (ADS)

Mishenina, T.; Pignatari, M.; Côté, B.; Thielemann, F.-K.; Soubiran, C.; Basak, N.; Gorbaneva, T.; Korotin, S. A.; Kovtyukh, V. V.; Wehmeyer, B.; Bisterzo, S.; Travaglio, C.; Gibson, B. K.; Jordan, C.; Paul, A.; Ritter, C.; Herwig, F.; NuGrid Collaboration

2017-08-01

Atmospheric parameters and chemical compositions for 10 stars with metallicities in the region of -2.2 < [Fe/H] < -0.6 were precisely determined using high-resolution, high signal-to-noise, spectra. For each star, the abundances, for 14-27 elements, were derived using both local thermodynamic equilibrium (LTE) and non-LTE (NLTE) approaches. In particular, differences by assuming LTE or NLTE are about 0.10 dex; depending on [Fe/H], Teff, gravity and element lines used in the analysis. We find that the O abundance has the largest error, ranging from 0.10 and 0.2 dex. The best measured elements are Cr, Fe, and Mn; with errors between 0.03 and 0.11 dex. The stars in our sample were included in previous different observational work. We provide a consistent data analysis. The data dispersion introduced in the literature by different techniques and assumptions used by the different authors is within the observational errors, excepting for HD103095. We compare these results with stellar observations from different data sets and a number of theoretical galactic chemical evolution (GCE) simulations. We find a large scatter in the GCE results, used to study the origin of the elements. Within this scatter as found in previous GCE simulations, we cannot reproduce the evolution of the elemental ratios [Sc/Fe], [Ti/Fe], and [V/Fe] at different metallicities. The stellar yields from core-collapse supernovae are likely primarily responsible for this discrepancy. Possible solutions and open problems are discussed.

[Effect of atmospheric CO2 concentration and nitrogen application level on absorption and transportation of nutrient elements in oilseed rape].

PubMed

Wang, Wen-ming; Zhang, Zhen-hua; Song, Hai-xing; Liu, Qiang; Rong, Xiang-min; Guan, Chun-yun; Zeng, Jing; Yuan, Dan

2015-07-01

Effect of elevated atmospheric-CO2 (780 µmol . mol-1) on the absorption and transportation of secondary nutrient elements (calcium, magnesium, sulphur) and micronutrient elements (iron, manganese, zinc, molybdenum and boron) in oilseed rape at the stem elongation stage were studied by greenhouse simulated method. Compared with the ambient CO2 condition, the content of Zn in stem was increased and the contents of other nutrient elements were decreased under the elevated atmospheric-CO2 with no nitrogen (N) application; the contents of Ca, S, B and Zn were increased, and the contents of Mg, Mn, Mo and Fe were decreased under the elevated atmospheric CO2 with N application (0.2 g N . kg-1 soil); except the content of Mo in leaf was increased, the contents of other nutrient elements were decreased under the elevated atmospheric-CO2 with two levels of N application. Compared with the ambient CO2 condition, the amounts of Ca and S relative to the total amount of secondary nutrient elements in stem and the amounts of B and Zn relative to the total amount of micronutrient elements in stem were increased under the elevated-CO2 treatment with both levels of N application, and the corresponding values of Mg, Fe, Mn and Mo were decreased; no-N application treatment increased the proportion of Ca distributed into the leaves, and the proportion of Mg distributed into leaves was increased by the normal-N application level; the proportions of Mn, Zn and Mo distributed into the leaves were increased at both N application levels. Without N application, the elevation of atmospheric CO2 increased the transport coefficients of SFe, Mo and SS,B, but decreased the transport coefficients of SMg,Fe, SMg, Mn and SS,Fe, indicating the proportions of Mo, S transported into the upper part of plant tissues was higher than that of Fe, and the corresponding value of B was higher than that observed for S, the corresponding value of Mg was higher than that of Fe and Mn. Under normal-N application, the elevation of atmospheric CO2 increased the transport coefficients of SMg,Fe, SMg,Mn and SS,B, but decreased the transport coefficients of SCa, Mg, SFe,Mo and SS,Fe indicating the proportions of Fe, Mn and Ca transported into the upper part of plant tissues was higher than that of Mg; the corresponding value of B was higher than that observed for S, the corresponding value of Fe was higher than that of Mo, and the corresponding value of S was higher than that of Fe.

Computing effective properties of random heterogeneous materials on heterogeneous parallel processors

NASA Astrophysics Data System (ADS)

Leidi, Tiziano; Scocchi, Giulio; Grossi, Loris; Pusterla, Simone; D'Angelo, Claudio; Thiran, Jean-Philippe; Ortona, Alberto

2012-11-01

In recent decades, finite element (FE) techniques have been extensively used for predicting effective properties of random heterogeneous materials. In the case of very complex microstructures, the choice of numerical methods for the solution of this problem can offer some advantages over classical analytical approaches, and it allows the use of digital images obtained from real material samples (e.g., using computed tomography). On the other hand, having a large number of elements is often necessary for properly describing complex microstructures, ultimately leading to extremely time-consuming computations and high memory requirements. With the final objective of reducing these limitations, we improved an existing freely available FE code for the computation of effective conductivity (electrical and thermal) of microstructure digital models. To allow execution on hardware combining multi-core CPUs and a GPU, we first translated the original algorithm from Fortran to C, and we subdivided it into software components. Then, we enhanced the C version of the algorithm for parallel processing with heterogeneous processors. With the goal of maximizing the obtained performances and limiting resource consumption, we utilized a software architecture based on stream processing, event-driven scheduling, and dynamic load balancing. The parallel processing version of the algorithm has been validated using a simple microstructure consisting of a single sphere located at the centre of a cubic box, yielding consistent results. Finally, the code was used for the calculation of the effective thermal conductivity of a digital model of a real sample (a ceramic foam obtained using X-ray computed tomography). On a computer equipped with dual hexa-core Intel Xeon X5670 processors and an NVIDIA Tesla C2050, the parallel application version features near to linear speed-up progression when using only the CPU cores. It executes more than 20 times faster when additionally using the GPU.

Accumulation of Metals in Juvenile Carp (Cyprinus carpio) Exposed to Sublethal Levels of Iron and Manganese: Survival, Body Weight and Tissue.

PubMed

Harangi, Sándor; Baranyai, Edina; Fehér, Milán; Tóth, Csilla Noémi; Herman, Petra; Stündl, László; Fábián, István; Tóthmérész, Béla; Simon, Edina

2017-05-01

Many oxbows are contaminated by Fe and Mn as a consequence of the elemental concentration of sediment and water originating from the Upper Tisza Region of Hungary. The phenomenon is partly caused by anthropogenic activities and mainly due to the geochemical characteristics of the region. The effects of Fe and Mn on the aquatic ecosystem of these wetlands were investigated in a model experiments in this study. Survival, individual body weight and the elemental concentrations of organs were determined in common carp (Cyprinus carpio) juveniles reared in Fe and Mn contaminated media (treatment 1: Fe 0.57 mg L -1 , Mn 0.29 mg L -1 , treatment 2: Fe 0.57 mg L -1 , Mn 0.625 mg L -1 , treatment 3: Fe 1.50 mg L -1 , Mn 0.29 mg L -1 , treatment 4: Fe 1.50 mg L -1 , Mn 0.625 mg L -1 and control: Fe 0.005 mg L -1 , Mn 0.003 mg L -1 ), for rearing time of 49 days. The treatment with Fe and Mn did not have any effect on the survival data and individual body weight in the levels tested. The highest concentration of Fe and Mn was found in the liver and brain of carp juveniles, while the lowest concentration of these elements occurred in the muscular tissue and gills. The treatment where Fe and Mn were applied in the highest concentrations resulted in a statistically higher level of these elements in the brain, grills and muscle tissues. The treatment where only Mn was present in the highest concentration caused increased level of Mn only in the liver. We found metal accumulation in almost every organ; however, the applied concentrations and exposure time did not affect the survival and average body weight of carp juveniles.

Plastic deformation of FeSi at high pressures: implications for planetary cores

NASA Astrophysics Data System (ADS)

Kupenko, Ilya; Merkel, Sébastien; Achorner, Melissa; Plückthun, Christian; Liermann, Hanns-Peter; Sanchez-Valle, Carmen

2017-04-01

The cores of terrestrial planets is mostly comprised of a Fe-Ni alloy, but it should additionally contain some light element(s) in order to explain the observed core density. Silicon has long been considered as a likely candidate because of geochemical and cosmochemical arguments: the Mg/Si and Fe/Si ratios of the Earth does not match those of the chondrites. Since silicon preferentially partition into iron-nickel metal, having 'missing' silicon in the core would solve this problem. Moreover, the evidence of present (e.g. Mercury) or ancient (e.g. Mars) magnetic fields on the terrestrial planets is a good indicator of (at least partially) liquid cores. The estimated temperature profiles of these planets, however, lay below iron melting curve. The addition of light elements in their metal cores could allow reducing their core-alloy melting temperature and, hence, the generation of a magnetic field. Although the effect of light elements on the stability and elasticity of Fe-Ni alloys has been widely investigated, their effect on the plasticity of core materials remains largely unknown. Yet, this information is crucial for understanding how planetary cores deform. Here we investigate the plastic deformation of ɛ-FeSi up to 50 GPa at room temperature employing a technique of radial x-ray diffraction in diamond anvil cells. Stoichiometric FeSi endmember is a good first-order approximation of the Fe-FeSi system and a good starting material to develop new experimental perspectives. In this work, we focused on the low-pressure polymorph of FeSi that would be the stable phase in the cores of small terrestrial planets. We will present the analysis of measured data and discuss their potential application to constrain plastic deformation in planetary cores.

Engine dynamic analysis with general nonlinear finite element codes. Part 2: Bearing element implementation overall numerical characteristics and benchmaking

NASA Technical Reports Server (NTRS)

Padovan, J.; Adams, M.; Fertis, J.; Zeid, I.; Lam, P.

1982-01-01

Finite element codes are used in modelling rotor-bearing-stator structure common to the turbine industry. Engine dynamic simulation is used by developing strategies which enable the use of available finite element codes. benchmarking the elements developed are benchmarked by incorporation into a general purpose code (ADINA); the numerical characteristics of finite element type rotor-bearing-stator simulations are evaluated through the use of various types of explicit/implicit numerical integration operators. Improving the overall numerical efficiency of the procedure is improved.

Global occurrence of tellurium-rich ferromanganese crusts and a model for the enrichment of tellurium

USGS Publications Warehouse

Hein, J.R.; Koschinsky, A.; Halliday, A.N.

2003-01-01

Hydrogenetic ferromanganese oxyhydroxide crusts (Fe-Mn crusts) precipitate out of cold ambient ocean water onto hard-rock surfaces (seamounts, plateaus, ridges) at water depths of about 400 to 4000 m throughout the ocean basins. The slow-growing (mm/Ma) Fe-Mn crusts concentrate most elements above their mean concentration in the Earth's crust. Tellurium is enriched more than any other element (up to about 50,000 times) relative to its Earth's crustal mean of about 1 ppb, compared with 250 times for the next most enriched element. We analyzed the Te contents for a suite of 105 bulk hydrogenetic crusts and 140 individual crust layers from the global ocean. For comparison, we analyzed 10 hydrothermal stratabound Mn-oxide samples collected from a variety of tectonic environments in the Pacific. In the Fe-Mn crust samples, Te varies from 3 to 205 ppm, with mean contents for Pacific and Atlantic samples of about 50 ppm and a mean of 39 ppm for Indian crust samples. Hydrothermal Mn samples have Te contents that range from 0.06 to 1 ppm. Continental margin Fe-Mn crusts have lower Te contents than open-ocean crusts, which is the result of dilution by detrital phases and differences in growth rates of the hydrogenetic phases. Correlation coefficient matrices show that for hydrothermal deposits, Te has positive correlations with elements characteristic of detrital minerals. In contrast, Te in open-ocean Fe-Mn crusts usually correlates with elements characteristic of the MnO2, carbonate fluorapatite, and residual biogenic phases. In continental margin crusts, Te also correlates with FeOOH associated elements. In addition, Te is negatively correlated with water depth of occurrence and positively correlated with crust thickness. Q-mode factor analyses support these relationships. However, sequential leaching results show that most of the Te is associated with FeOOH in Fe-Mn crusts and ???10% is leached with the MnO2. Thermodynamic calculations indicate that Te occurs predominantly as H5TeO6- in ocean water. The speciation of Te in ocean water and charge balance considerations indicate that Te should be scavenged by FeOOH, which is in agreement with our leaching results. The thermodynamically more stable Te(IV) is less abundant by factors of 2 to 3.5 than Te(VI) in ocean water. This can be explained by preferential (not exclusive) scavenging of Te(IV) by FeOOH at the Fe-Mn crust surface and by Fe-Mn colloids in the water column. We propose a model in which the extreme enrichment of Te in Fe-Mn crusts is likely the result of an oxidation reaction on the surface of FeOOH. A similar oxidation process has been confirmed for Co, Ce, and Tl at the surface of MnO2 in crusts, but has not been suggested previously to occur in association with FeOOH in Fe-Mn crusts. Mass-balance considerations indicate that ocean floor Fe-Mn deposits are the major sink for Te in the oceans. The concentration and redox chemistry of Te in the global ocean are likely controlled by scavenging on Fe-Mn colloids in the water column and Fe-Mn deposits on the ocean floor, as is also the case for Ce. ?? 2003 Elsevier Science Ltd.

A comparison of the techniques of PIXE, PIGE and INAA by reference to the elemental analysis of porcine brain samples

NASA Astrophysics Data System (ADS)

Stedman, J. D.; Spyrou, N. M.

1994-12-01

The trace element concentrations in porcine brain samples as determined by particle-induced X-ray emission (PIXE) analysis, instrumental neutron activation analysis (INAA) and particle-induced gamma-ray emission (PIGE) analysis are compared. The matrix composition was determined by Rutherford backscattering (RBS). Al, Si, P, S, Cl, K, Ca, Mn, Fe and Cd were determined by PIXE analysis Na, K, Sc, Fe, Co, Zn, As, Br, Rb, and Cs by INAA and Na, Mg and Fe by PIGE analysis. The bulk elements C, N, O, Na Cl and S were found by RBS analysis. Elemental concentrations are obtained using the comparator method of analysis rather than an absolute method, the validity which is examined by comparing the elemental concentrations obtained in porcine brain using two separate certified reference materials.

Characterization of members to stellar kinematic groups using chemical tagging

NASA Astrophysics Data System (ADS)

Tabernero, H. M.

2014-10-01

In this thesis we have characterized more than one thousand late-type stars. For this characterization we have been making use of high resolution spectroscopy (R > 40,000) taken in different spectrographs, HERMES at the Mercator telescope in La Palma, FOCES in the 2.2m telescope at Calar Alto, the Coudé-Echelle spectrograph at 2 m-the Alfred- Jensch-Teleskop in Tautenburg, and UVES at the Very Large Telescope in La Silla. Stellar spectroscopy, in particular at high-resolution, is a modern tool that allows us to extract a lot of information of a given star. In particular, we have obtained their atmospheric parameters, namely: effective temperature (Teff), surface gravity (log g), microturbulent velocity (ξ), and iron abundance ([Fe/H], used as a metallicity proxy). An automatic code (StePar) has been developed. This code allows to derive stellar atmospheric parameters (Teff , log g, ξ, and [Fe/H]) only in a few minutes. Also, with these parameters at hand we have derived chemical abundances for 20 different chemical elements: Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Ba, Ce, and Nd, which offer many or at least some isolated transitions in the wavelength range of the spectra taken with these spectrographs. This work comprises two publications in Astronomy & Astrophysics. The first one is about chemical tagging applied to the Hyades SC (see Chapter 2 or Tabernero et al. 2012). The second paper is a in-depth study of the chemical composition of candidate members to the Ursa Major MG (see Chapter 3 or Tabernero et al. 2015). Additionally there is another chapter that comprises the analysis of Galactic stars within the GAIA ESO Survey stars (GES, Gilmore et al. 2012; Randich & Gilmore 2013) whose data have contributed to the publication of some release (Lanzafame et al. 2014; Smiljanic et al. 2014) and science papers (Jofre et al. 2014; Sousa et al. 2014; Spina et al. 2014a,b) that made use the survey results. The two papers included in this thesis deal with the characterization of late-type stars (F, G, and K spectral types). In particular, this thesis is based on the determination of stellar atmospheric parameters and element abundances.

Titanium as a Beneficial Element for Crop Production

PubMed Central

Lyu, Shiheng; Wei, Xiangying; Chen, Jianjun; Wang, Cun; Wang, Xiaoming; Pan, Dongming

2017-01-01

Titanium (Ti) is considered a beneficial element for plant growth. Ti applied via roots or leaves at low concentrations has been documented to improve crop performance through stimulating the activity of certain enzymes, enhancing chlorophyll content and photosynthesis, promoting nutrient uptake, strengthening stress tolerance, and improving crop yield and quality. Commercial fertilizers containing Ti, such as Tytanit and Mg-Titanit, have been used as biostimulants for improving crop production; however, mechanisms underlying the beneficial effects still remain unclear. In this article, we propose that the beneficial roles Ti plays in plants lie in its interaction with other nutrient elements primarily iron (Fe). Fe and Ti have synergistic and antagonistic relationships. When plants experience Fe deficiency, Ti helps induce the expression of genes related to Fe acquisition, thereby enhancing Fe uptake and utilization and subsequently improving plant growth. Plants may have proteins that either specifically or nonspecifically bind with Ti. When Ti concentration is high in plants, Ti competes with Fe for ligands or proteins. The competition could be severe, resulting in Ti phytotoxicity. As a result, the beneficial effects of Ti become more pronounced during the time when plants experience low or deficient Fe supply. PMID:28487709

A Comprehensive Structural Dynamic Analysis Approach for Multi Mission Earth Entry Vehicle (MMEEV) Development

NASA Technical Reports Server (NTRS)

Perino, Scott; Bayandor, Javid; Siddens, Aaron

2012-01-01

The anticipated NASA Mars Sample Return Mission (MSR) requires a simple and reliable method in which to return collected Martian samples back to earth for scientific analysis. The Multi-Mission Earth Entry Vehicle (MMEEV) is NASA's proposed solution to this MSR requirement. Key aspects of the MMEEV are its reliable and passive operation, energy absorbing foam-composite structure, and modular impact sphere (IS) design. To aid in the development of an EEV design that can be modified for various missions requirements, two fully parametric finite element models were developed. The first model was developed in an explicit finite element code and was designed to evaluate the impact response of the vehicle and payload during the final stage of the vehicle's return to earth. The second model was developed in an explicit code and was designed to evaluate the static and dynamic structural response of the vehicle during launch and reentry. In contrast to most other FE models, built through a Graphical User Interface (GUI) pre-processor, the current model was developed using a coding technique that allows the analyst to quickly change nearly all aspects of the model including: geometric dimensions, material properties, load and boundary conditions, mesh properties, and analysis controls. Using the developed design tool, a full range of proposed designs can quickly be analyzed numerically and thus the design trade space for the EEV can be fully understood. An engineer can then quickly reach the best design for a specific mission and also adapt and optimize the general design for different missions.

Platinum group elements and gold in ferromanganese crusts from Afanasiy-Nikitin seamount, equatorial Indian Ocean: Sources and fractionation

USGS Publications Warehouse

Banakar, V.K.; Hein, J.R.; Rajani, R.P.; Chodankar, A.R.

2007-01-01

The major element relationships in ferromanganese (Fe-Mn) crusts from Afanasiy-Nikitin seamount (ANS), eastern equatorial Indian Ocean, appear to be atypical. High positive correlations (r = 0.99) between Mn/Co and Fe/Co ratios, and lack of correlation of those ratios with Co, Ce, and Ce/Co, indicate that the ANS Fe-Mn crusts are distinct from Pacific seamount Fe-Mn crusts, and reflect region-specific chemical characteristics. The platinum group elements (PGE: Ir, Ru, Rh, Pt, and Pd) and Au in ANS Fe-Mn crusts are derived from seawater and are mainly of terrestrial origin, with a minor cosmogenic component. The Ru/Rh (0.5-2) and Pt/Ru ratios (7-28) are closely comparable to ratios in continental basalts, whereas Pd/Ir ratios exhibit values ( 0.75) correlations between water depth and Mn/Co, Fe/Co, Ce/Co, Co, and the PGEs. Fractionation of the PGE-Au from seawater during colloidal precipitation of the major-oxide phases is indicated by well-defined linear positive correlations (r > 0.8) of Co and Ce with Ir, Ru, Rh, and Pt; Au/Co with Mn/Co; and by weak or no correlations of Pd with water depth, Co-normalized major-element ratios, and with the other PGE (r < 0.5). The strong enrichment of Pt (up to 1 ppm) relative to the other PGE and its positive correlations with Ce and Co demonstrate a common link for the high concentrations of all three elements, which likely involves an oxidation reaction on the Mn-oxide and Fe-oxyhydroxide surfaces. The documented fractionation of PGE-Au and their positive association with redox sensitive Co and Ce may have applications in reconstructing past-ocean redox conditions and water masses.

The effects of Fe-oxidizing microorganisms on post-biostimulation permeability reduction and oxidative processes at the Rifle IFRC site

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

Chan, Clara Sze-Yue

2015-07-02

Fe oxidation and biomineral formation is important in aquifers because the highly-reactive oxides can control the mobility of nutrients (e.g. phosphate, C) and metals (e.g. arsenic, uranium). Mineral formation also has the potential to affect hydrology, depending on the volume and distribution in pore spaces. In this exploratory study, we sought to understand how microbial Fe-oxidizers and their biominerals affect, and are affected by groundwater flow. As part of work at the Rifle aquifer in Colorado, we initially hypothesized that Fe-oxidizers were contributing to aquifer clogging problems associated with enhanced bioremediation. To demonstrate the presence of Fe-oxidizers in the Riflemore » aquifer, we enriched FeOM from groundwater samples, and isolated two novel chemolithotrophic, microaerophilic Fe-oxidizing Betaproteobacteria, Hydrogenophaga sp. P101 and Curvibacter sp. CD03. To image cells and biominerals in the context of pores, we developed a “micro-aquifer,” a sand-filled flow-through culture chamber that allows for imaging of sediment pore space with multiphoton confocal microscopy. Fe oxide biofilms formed on sand grains, demonstrating that FeOM produce Fe oxide sand coatings. Fe coatings are common on aquifer sands, and tend to sequester contaminants; however, it has never previously been shown that microbes are responsible for their formation. In contrast to our original hypothesis, the biominerals did not clog the mini-aquifer. Instead, Fe biofilm distribution was dynamic: they grew as coatings, then periodically sloughed off sand grains, with some flocs later caught in pore throats. This has implications for physical hydrology, including pore scale architecture, and element transport. The sloughing of coatings likely prevents the biominerals from clogging wells and aquifers, at least initially. Although attached biomineral coatings sequester Fe-associated elements (e.g. P, As, C, U), when biominerals detach, these elements are transported as particles through the aquifer. Our work shows that microbial mineralization impacts in aquifers are dynamic, and that the fate and transport of biomineral-associated elements depend not only on geochemical conditions, but also physical pore-scale processes.« less

The Abundances of the Iron Group Elements in Early B Stars in the Magellanic Clouds

NASA Astrophysics Data System (ADS)

Peters, C.

FUSE observations of four sharp-lined early B main-sequence band stars in the Magellanic Clouds will be carried through to determine the abundances of the heavy elements, especially those of the Fe group. The FUSE spectral region contains numerous Fe III lines, including the resonance multiplet (UV1) near 1130 A that is excellent for abundance determinations and two strong multiplets of V III, an ion that does not produce measurable lines longward of 1200 A in metal-deficient stars. In addition there are several measurable lines from Cr III and Mn III. Although abundances of the Fe-peak elements are of interest because they are important for assessing opacities for stellar evolution calculations and the validity of theoretical calculations of explosive nucleosynthesis, ground-based studies do not yield this information because measurable lines from these species, except for a few Fe III lines, are found only in the UV spectral region. The abundances of heavy elements provide information on the production of such elements in previous generations of stars. From FUSE data obtained in Cycle 3 we are determining the abundances of the Fe group elements in two sharp-lined early B stars in the SMC (AV 304, a field star, and NGC346-637, a star in a mini-starburst cluster). This project will allow one to compare the abundances in AV 304 and NGC346-637 with those in the LMC and other regions in the SMC and look for asymmetry in heavy element production in the Magellanic Clouds.

VizieR Online Data Catalog: Atomic data for X-ray lines of FeVIII and FeIX (O'Dwyer+, 2012)

NASA Astrophysics Data System (ADS)

O'Dwyer, B.; Del Zanna, G.; Badnell, N. R.; Mason, H. E.; Storey, P. J.

2012-04-01

The distorted wave extension of the autostructure code has been used to calculate energy levels, radiative transition probabilities and collisional excitation rates of Fe VIII and Fe IX up to n=6 for Fe IX and n=7 for Fe VIII. We have compared some of the data with previous calculations, finding overall agreement for radiative transition rates, but interesting differences for some collisional data. ************************************************************************** * * * Sorry, but the author(s) never supplied the tabular material * * announced in the paper * * * **************************************************************************

The origin of diverse α-element abundances in galaxy discs

NASA Astrophysics Data System (ADS)

Mackereth, J. Ted; Crain, Robert A.; Schiavon, Ricardo P.; Schaye, Joop; Theuns, Tom; Schaller, Matthieu

2018-07-01

Spectroscopic surveys of the Galaxy reveal that its disc stars exhibit a spread in [α/Fe] at fixed [Fe/H], manifest at some locations as a bimodality. The origin of these diverse, and possibly distinct, stellar populations in the Galactic disc is not well understood. We examine the Fe and α-element evolution of 133 Milky Way-like galaxies from the EAGLE simulation, to investigate the origin and diversity of their [α/Fe]-[Fe/H] distributions. We find that bimodal [α/Fe] distributions arise in galaxies whose gas accretion histories exhibit episodes of significant infall at both early and late times, with the former fostering more intense star formation than the latter. The shorter characteristic consumption time-scale of gas accreted in the earlier episode suppresses its enrichment with iron synthesized by Type Ia SNe, resulting in the formation of a high-[α/Fe] sequence. We find that bimodality in [α/Fe] similar to that seen in the Galaxy is rare, appearing in approximately 5 per cent of galaxies in our sample. We posit that this is a consequence of an early gas accretion episode requiring the mass accretion history of a galaxy's dark matter halo to exhibit a phase of atypically rapid growth at early epochs. The scarcity of EAGLE galaxies exhibiting distinct sequences in the [α/Fe]-[Fe/H] plane may therefore indicate that the Milky Way's elemental abundance patterns, and its accretion history, are not representative of the broader population of ˜L⋆ disc galaxies.

The origin of diverse α-element abundances in galaxy discs

NASA Astrophysics Data System (ADS)

Mackereth, J. Ted; Crain, Robert A.; Schiavon, Ricardo P.; Schaye, Joop; Theuns, Tom; Schaller, Matthieu

2018-04-01

Spectroscopic surveys of the Galaxy reveal that its disc stars exhibit a spread in [α/Fe] at fixed [Fe/H], manifest at some locations as a bimodality. The origin of these diverse, and possibly distinct, stellar populations in the Galactic disc is not well understood. We examine the Fe and α-element evolution of 133 Milky Way-like galaxies from the EAGLE simulation, to investigate the origin and diversity of their [α/Fe]-[Fe/H] distributions. We find that bimodal [α/Fe] distributions arise in galaxies whose gas accretion histories exhibit episodes of significant infall at both early and late times, with the former fostering more intense star formation than the latter. The shorter characteristic consumption timescale of gas accreted in the earlier episode suppresses its enrichment with iron synthesised by Type Ia SNe, resulting in the formation of a high-[α/Fe] sequence. We find that bimodality in [α/Fe] similar to that seen in the Galaxy is rare, appearing in approximately 5 percent of galaxies in our sample. We posit that this is a consequence of an early gas accretion episode requiring the mass accretion history of a galaxy's dark matter halo to exhibit a phase of atypically-rapid growth at early epochs. The scarcity of EAGLE galaxies exhibiting distinct sequences in the [α/Fe]-[Fe/H] plane may therefore indicate that the Milky Way's elemental abundance patterns, and its accretion history, are not representative of the broader population of ˜L⋆ disc galaxies.

Trace elements records from vermetids aragonite as millennial paleo-oceanographic archives in the South-East Mediterranean

NASA Astrophysics Data System (ADS)

Jacobson, Yitzhak; Yam, Ruth; Shemesh, Aldo

2017-04-01

The Mediterranean Sea is a region under high anthropogenic stress, thus a hotspot for climate change studies. Natural conditions, such as SST, productivity, precipitation and dust fluxes along with human induced activity affect seawater chemistry. We study millennial variability of trace elements in East Mediterranean Sea high-resolution records, in attempt to connect them to environmental factors. The Mediterranean reef builder Vermetid, D. petraeum is a sessile gastropod, secreting its aragonite shells in tidal zones. Cores of Vermetid reefs from the South Eastern Mediterranean (Israel) were previously analyzed by Sisma?Ventura et al. (2014) to reconstruct seawater surface temperature (SST) and δ13C of dissolved inorganic carbon (DIC). In this study we analyzed trace elements of these vermetid cores, and reconstructed millennial records of elements to calcium (el/Ca) molar ratios. Vermetid trace element contents from recent decades are mostly in agreement with known values for marine biogenic aragonites from corals and mollusk. We divide vermetid trace element records into three element groups: 1) Sr and U are related to SST and DIC. These elements correlate with major climatic events of the last millennium, such as the Medieval Warm Period (900-1300 AD) and the Little Ice Age (1450-1850 AD). 2) Pb and Cd are related to anthropogenic pollution and demonstrate industrial sourced trends throughout the anthropocene (since 1750 AD). 3) Terrogenous elements, including Fe, Al, Mn and V. Al in seawater and sediments has been used to trace water masses and land derived sediment source. We observe a major change in average vermetid Al/Fe ratios from 0.5 to 2.5 over the recorded period (n=72). This vermetid Al/Fe change points at a possible shift from Nilotic sediments (0.1-0.5 Al/Fe molar ratio) to Saharan dust ratio (2-4 Al/Fe molar ratio). Mn and V show a similar variability to Fe. Understanding the variability of vermetid TE can help us interpret the relative dominance of different climate systems and anthropogenic processes on the East Mediterranean environment.

Abundances in very metal-poor stars

NASA Astrophysics Data System (ADS)

Johnson, Jennifer Anne

We measured the abundances of 35 elements in 22 field red giants and a red giant in the globular cluster M92. We found the [Zn/Fe] ratio increases with decreasing [Fe/H], reaching ~0.3 at [Fe/H] = -3.0. While this is a larger [Zn/Fe] than found by previous investigators, it is not sufficient to account for the [Zn/Fe] observed in the damped Lyα systems. We test different models for the production of the s-process elements by comparing our [Y/Zr] values, which have been produced by the r- process, to predictions of what the s-process does not produce. We find that the models of Arlandini et al. (1999), which calculate s-process production in a model AGB star, agree the best. We then look at the r-process abundances across a wide range in mass. The [Y/Ba] values for most of our stars cluster around -0.30, but there are three outliers with [Y/Ba] values up to 1 dex higher. Thus the heavy element abundances do not show the same pattern from Z = 39 to Z = 56. However, our abundances ratios from Pd (Z = 46) to Yb (Z = 70) are consistent with a scaled solar system r- process pattern, arguing that at least the heavy r- process elements are made in a universal pattern. If we assume that this same pattern hold through thorium, we can determine the ages of our stars from the present abundance of radioactive thorium and an initial thorium abundance based on the abundance of stable heavy elements. Our results for five stars are consistent with those stars being the same age. Our mean age is 10.8 +/- 2 Gyr. However that result depends critically on the assumed Th/stable ratio, which we adopt from models of the r-process. For an average age of 15 Gyrs, the initial Th/Eu ratio we would need is 0.590. Finally, the [element/Fe] ratios for elements in the iron group and lower do not show any dispersion, unlike for the r- process elements such as Y and Ba. Therefore the individual contributions of supernovae have been erased for the lighter elements.

A Finite Element Model of the THOR-K Dummy for Aerospace and Aircraft Impact Simulations

NASA Technical Reports Server (NTRS)

Putnam, Jacob; Untaroiu, Costin D.; Somers, Jeffrey T.; Pellettiere, Joseph

2013-01-01

1) Update and Improve the THOR Finite Element (FE) model to specifications of the latest mod kit (THOR-K). 2) Evaluate the kinematic and kinetic response of the FE model in frontal, spinal, and lateral impact loading conditions.

Driving forces of redistribution of elements during quasicrystalline phase formation under heating of mechanically alloyed Al65Cu23Fe12 powder

NASA Astrophysics Data System (ADS)

Tcherdyntsev, V. V.; Kaloshkin, S. D.; Shelekhov, E. V.; Principi, G.; Rodin, A. O.

2008-02-01

Al65Cu23Fe12 alloys were prepared by ball milling of the elemental powders mixture. Phase and structural transformations at heating of as-milled powders were investigated by X-ray diffraction analysis. Precision analysis of Mössbauer spectra was performed to check the adequacy of the fitting of X-ray diffraction patterns. The results were compared with the data of differential scanning and solution calorimetry, as well as with the thermodynamic literature data, in order to estimate the driving forces of redistribution of elements that preceded the formation of single-phase quasicrystalline structure. The heat of elements mixing, which is positive for Cu-Fe system and negative for Al-Fe and Al-Cu systems, was supposed to be a decisive factor for phase transformations during heating of the alloy. The correlation between sequence of phase transformations during heating and the thermodynamic data was discussed and the scheme describing phase transformations observed was proposed.

Unraveling the molecular mechanisms of nitrogenase conformational protection against oxygen in diazotrophic bacteria.

PubMed

Lery, Letícia M S; Bitar, Mainá; Costa, Mauricio G S; Rössle, Shaila C S; Bisch, Paulo M

2010-12-22

G. diazotrophicus and A. vinelandii are aerobic nitrogen-fixing bacteria. Although oxygen is essential for the survival of these organisms, it irreversibly inhibits nitrogenase, the complex responsible for nitrogen fixation. Both microorganisms deal with this paradox through compensatory mechanisms. In A. vinelandii a conformational protection mechanism occurs through the interaction between the nitrogenase complex and the FeSII protein. Previous studies suggested the existence of a similar system in G. diazotrophicus, but the putative protein involved was not yet described. This study intends to identify the protein coding gene in the recently sequenced genome of G. diazotrophicus and also provide detailed structural information of nitrogenase conformational protection in both organisms. Genomic analysis of G. diazotrophicus sequences revealed a protein coding ORF (Gdia0615) enclosing a conserved "fer2" domain, typical of the ferredoxin family and found in A. vinelandii FeSII. Comparative models of both FeSII and Gdia0615 disclosed a conserved beta-grasp fold. Cysteine residues that coordinate the 2[Fe-S] cluster are in conserved positions towards the metallocluster. Analysis of solvent accessible residues and electrostatic surfaces unveiled an hydrophobic dimerization interface. Dimers assembled by molecular docking presented a stable behaviour and a proper accommodation of regions possibly involved in binding of FeSII to nitrogenase throughout molecular dynamics simulations in aqueous solution. Molecular modeling of the nitrogenase complex of G. diazotrophicus was performed and models were compared to the crystal structure of A. vinelandii nitrogenase. Docking experiments of FeSII and Gdia0615 with its corresponding nitrogenase complex pointed out in both systems a putative binding site presenting shape and charge complementarities at the Fe-protein/MoFe-protein complex interface. The identification of the putative FeSII coding gene in G. diazotrophicus genome represents a large step towards the understanding of the conformational protection mechanism of nitrogenase against oxygen. In addition, this is the first study regarding the structural complementarities of FeSII-nitrogenase interactions in diazotrophic bacteria. The combination of bioinformatic tools for genome analysis, comparative protein modeling, docking calculations and molecular dynamics provided a powerful strategy for the elucidation of molecular mechanisms and structural features of FeSII-nitrogenase interaction.

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

Milani, Gabriele, E-mail: milani@stru.polimi.it, E-mail: gabriele.milani@polimi.it; Valente, Marco

This study presents some FE results regarding the behavior under horizontal loads of eight existing masonry towers located in the North-East of Italy. The towers, albeit unique for geometric and architectural features, show some affinities which justify a comparative analysis, as for instance the location and the similar masonry material. Their structural behavior under horizontal loads is therefore influenced by geometrical issues, such as slenderness, walls thickness, perforations, irregularities, presence of internal vaults, etc., all features which may be responsible for a peculiar output. The geometry of the towers is deduced from both existing available documentation and in-situ surveys. Onmore » the basis of such geometrical data, a detailed 3D realistic mesh is conceived, with a point by point characterization of each single geometric element. The FE models are analysed under seismic loads acting along geometric axes of the plan section, both under non-linear static (pushover) and non-linear dynamic excitation assumptions. A damage-plasticity material model exhibiting softening in both tension and compression, already available in the commercial code Abaqus, is used for masonry. Pushover analyses are performed with both G1 and G2 horizontal loads distribution, according to Italian code requirements, along X+/− and Y+/− directions. Non-linear dynamic analyses are performed along both X and Y directions with a real accelerogram scaled to different peak ground accelerations. Some few results are presented in this paper. It is found that the results obtained with pushover analyses reasonably well fit expensive non-linear dynamic simulations, with a slightly less conservative trend.« less

Impact of Stellar Convection Criteria on the Nucleosynthetic Yields of Population III Supernovae.

NASA Astrophysics Data System (ADS)

Teffs, Jacob; Young, Tim; Lawlor, Tim

2018-01-01

A grid of 15-80 solar mass Z=0 stellar models are evolved to pre-core collapse using the stellar evolution code BRAHAMA. Each initial zero-age main sequence mass model star is evolved with two different convection criteria, Ledoux and Schwarzchild. The choice of convection produces significant changes in the evolutionary model tracks on the HR diagram, mass loss, and interior core and envelope structures. At onset of core collapse, a SNe explosion is initiated using a one-dimensional radiation-hydrodynamics code and followed for 400 days. The explosion energy is varied between 1-10 foes depending on the model as there are no observationally determined energies for population III supernovae. Due to structure differences, the Schwarzchild models resemble Type II-P SNe in their lightcurve while the Ledoux models resemble SN1987a, a Type IIpec. The nucleosynthesis is calculated using TORCH, a 3,208 isotope network, in a post process method using the hydrodynamic history. The Ledoux models have, on average, higher yields for elements above Fe compared to the Schwarzchild. Using a Salpeter IMF and other recently published population III IMF’s, the net integrated yields per solar mass are calculated and compared to published theoretical results and to published observations of extremely metal poor halo stars of [Fe/H] < -3. Preliminary results show the lower mass models of both criteria show similar trends to the extremely metal poor halo stars but more work and analysis is required.

A comparison of FE beam and continuum elements for typical nitinol stent geometries

NASA Astrophysics Data System (ADS)

Ballew, Wesley; Seelecke, Stefan

2009-03-01

With interest in improved efficiency and a more complete description of the SMA material, this paper compares finite element (FE) simulations of typical stent geometries using two different constitutive models and two different element types. Typically, continuum elements are used for the simulation of stents, for example the commercial FE software ANSYS offers a continuum element based on Auricchio's SMA model. Almost every stent geometry, however, is made up of long and slender components and can be modeled more efficiently, in the computational sense, with beam elements. Using the ANSYS user programmable material feature, we implement the free energy based SMA model developed by Mueller and Seelecke into the ANSYS beam element 188. Convergence behavior for both, beam and continuum formulations, is studied in terms of element and layer number, respectively. This is systematically illustrated first for the case of a straight cantilever beam under end loading, and subsequently for a section of a z-bend wire, a typical stent sub-geometry. It is shown that the computation times for the beam element are reduced to only one third of those of the continuum element, while both formulations display a comparable force/displacement response.

Distribution of Ca, Fe, Cu and Zn in primary colorectal cancer and secondary colorectal liver metastases

NASA Astrophysics Data System (ADS)

Al-Ebraheem, A.; Mersov, A.; Gurusamy, K.; Farquharson, M. J.

2010-07-01

A microbeam synchrotron X-ray fluorescence (μSRXRF) technique has been used to determine the localization and the relative concentrations of Zn, Cu, Fe and Ca in primary colorectal cancer and secondary colorectal liver metastases. 24 colon and 23 liver samples were examined, all of which were formalin fixed tissues arranged as microarrays of 1.0 mm diameter and 10 μm thickness. The distribution of these metals was compared with light transmission images of adjacent sections that were H and E stained to reveal the location of the cancer cells. Histological details were provided for each sample which enable concentrations of all elements in different tissue types to be compared. In the case of liver, significant differences have been found for all elements when comparing tumour, normal, necrotic, fibrotic, and blood vessel tissues (Kruskal Wallis Test, P<0.0001). The concentrations of all elements have also been found to be significantly different among tumour, necrotic, fibrotic, and mucin tissues in the colon samples (Kruskal Wallis Test, P<0.0001). The concentrations of all elements have been compared between primary colorectal samples and colorectal liver metastases. Concentration of Zn, Cu, Fe and Ca are higher in all types of liver tissues compared to those in the colon tissues. Comparing liver tumour and colon tumour samples, significant differences have been found for all elements (Mann Whitney, P<0.0001). For necrotic tissues, significant increase has been found for Zn, Ca, Cu and Fe (Mann Whitney, P<0.0001 for Fe and Zn, 0.014 for Ca, and 0.001 for Cu). The liver fibrotic levels of Zn, Ca, Cu and Fe were higher than the fibrotic colon areas (independent T test, P=0.007 for Zn and Mann Whitney test P<0.0001 for Cu, Fe and Ca). For the blood vessel tissue, the analysis revealed that the difference was only significant for Fe ( P=0.009) from independent T test.

Synthesis of Xenon and Iron-Nickel Intermetallic Compounds at Earth’s Core Thermodynamic Conditions

DOE PAGES

Stavrou, Elissaios; Yao, Yansun; Goncharov, Alexander F.; ...

2018-02-28

In this study, using in situ synchrotron x-ray diffraction and Raman spectroscopy in concert with first principles calculations we demonstrate the synthesis of stable Xe(Fe ,Fe/Ni) 3 and XeNi 3 compounds at thermodynamic conditions representative of Earth’s core. Surprisingly, in the case of both the Xe-Fe and Xe-Ni systems Fe and Ni become highly electronegative and can act as oxidants. In conclusion, the results indicate the changing chemical properties of elements under extreme conditions by documenting that electropositive at ambient pressure elements could gain electrons and form anions.

A combined experimental and finite element analysis method for the estimation of eddy-current loss in NdFeB magnets.

PubMed

Fratila, Radu; Benabou, Abdelkader; Tounzi, Abdelmounaïm; Mipo, Jean-Claude

2014-05-14

NdFeB permanent magnets (PMs) are widely used in high performance electrical machines, but their relatively high conductivity subjects them to eddy current losses that can lead to magnetization loss. The Finite Element (FE) method is generally used to quantify the eddy current loss of PMs, but it remains quite difficult to validate the accuracy of the results with complex devices. In this paper, an experimental test device is used in order to extract the eddy current losses that are then compared with those of a 3D FE model.

Defining the Architecture of the Core Machinery for the Assembly of Fe-S Clusters in Human Mitochondria.

PubMed

Gakh, Oleksandr; Ranatunga, Wasantha; Galeano, Belinda K; Smith, Douglas S; Thompson, James R; Isaya, Grazia

2017-01-01

Although Fe-S clusters may assemble spontaneously from elemental iron and sulfur in protein-free systems, the potential toxicity of free Fe 2+ , Fe 3+ , and S 2- ions in aerobic environments underscores the requirement for specialized proteins to oversee the safe assembly of Fe-S clusters in living cells. Prokaryotes first developed multiprotein systems for Fe-S cluster assembly, from which mitochondria later derived their own system and became the main Fe-S cluster suppliers for eukaryotic cells. Early studies in yeast and human mitochondria indicated that Fe-S cluster assembly in eukaryotes is centered around highly conserved Fe-S proteins (human ISCU) that serve as scaffolds upon which new Fe-S clusters are assembled from (i) elemental sulfur, provided by a pyridoxal phosphate-dependent cysteine desulfurase (human NFS1) and its stabilizing-binding partner (human ISD11), and (ii) elemental iron, provided by an iron-binding protein of the frataxin family (human FXN). Further studies revealed that all of these proteins could form stable complexes that could reach molecular masses of megadaltons. However, the protein-protein interaction surfaces, catalytic mechanisms, and overall architecture of these macromolecular machines remained undefined for quite some time. The delay was due to difficulties inherent in reconstituting these very large multiprotein complexes in vitro or isolating them from cells in sufficient quantities to enable biochemical and structural studies. Here, we describe approaches we developed to reconstitute the human Fe-S cluster assembly machinery in Escherichia coli and to define its remarkable architecture. © 2017 Elsevier Inc. All rights reserved.

FE calculations on a three stage metal forming process of Sandvik Nanoflex™

NASA Astrophysics Data System (ADS)

Voncken, R. M. J.; van der Sluis, O.; Post, J.; Huétink, J.

2004-06-01

Sandvik Nanoflex™ combines good corrosion resistance with high strength. This steel has good deformability in austenitic conditions. It belongs to the group of metastable austenites, which means that during deformation a strain-induced transformation into martensite takes place. After deformation, transformation continues as a result of internal stresses. Both transformations are stress-state and temperature dependent. A constitutive model for this steel has been formulated, based on the macroscopic material behaviour measured by inductive measurements. Both the stress-assisted and the strain-induced transformation into martensite have been incorporated in this model. Path-dependent work hardening has also been taken into account. This article describes how the model is implemented in an internal Philips FE code called Crystal, which is a dedicated robust and accurate finite element solver. The implementation is based on lookup tables in combination with feed-forward neural networks. The radial return method is used to determine the material state during and after plastic flow, however, it has been extended to cope with the stiff character of the partial differential equation that describes the transformation behaviour.

Evidence for regulation of columnar habit in apple by a putative 2OG-Fe(II) oxygenase.

PubMed

Wolters, Pieter J; Schouten, Henk J; Velasco, Riccardo; Si-Ammour, Azeddine; Baldi, Paolo

2013-12-01

Understanding the genetic mechanisms controlling columnar-type growth in the apple mutant 'Wijcik' will provide insights on how tree architecture and growth are regulated in fruit trees. In apple, columnar-type growth is controlled by a single major gene at the Columnar (Co) locus. By comparing the genomic sequence of the Co region of 'Wijcik' with its wild-type 'McIntosh', a novel non-coding DNA element of 1956 bp specific to Pyreae was found to be inserted in an intergenic region of 'Wijcik'. Expression analysis of selected genes located in the vicinity of the insertion revealed the upregulation of the MdCo31 gene encoding a putative 2OG-Fe(II) oxygenase in axillary buds of 'Wijcik'. Constitutive expression of MdCo31 in Arabidopsis thaliana resulted in compact plants with shortened floral internodes, a phenotype reminiscent of the one observed in columnar apple trees. We conclude that MdCo31 is a strong candidate gene for the control of columnar growth in 'Wijcik'. No claim to original European Union works. New Phytologist © 2013 New Phytologist Trust.

Fe-C and Fe-H systems at pressures of the Earth's inner core

NASA Astrophysics Data System (ADS)

Bazhanova, Zulfiya G.; Oganov, Artem R.; Gianola, Omar

2012-05-01

The solid inner core of Earth is predominantly composed of iron alloyed with several percent Ni and some lighter elements, Si, S, O, H, and C being the prime candidates. To establish the chemical composition of the inner core, it is necessary to find the range of compositions that can explain its observed characteristics. Recently, there have been a growing number of papers investigating C and H as possible light elements in the core, but the results were contradictory. Here, using ab initio simulations, we study the Fe-C and Fe-H systems at inner core pressures (330-364 GPa). Based on the evolutionary structure prediction algorithm USPEX, we have determined the lowest-enthalpy structures of all possible carbides (FeC, Fe2C, Fe3C, Fe4C, FeC2, FeC3, FeC4, Fe7C3) and hydrides (Fe4H, Fe3H, Fe2H, FeH, FeH2, FeH3, FeH4) and have found that Fe2C (space group Pnma) is the most stable iron carbide at pressures of the inner core, while FeH, FeH3, and FeH4 are the most stable iron hydrides at these conditions. For Fe3C, the cementite structure (space group Pnma) and the Cmcm structure recently found by random sampling are less stable than the I-4 and C2/m structures predicted here. We have found that FeH3 and FeH4 adopt chemically interesting thermodynamically stable crystal structures, containing trivalent iron in both compounds. We find that the density of the inner core can be matched with a reasonable concentration of carbon, 11-15 mol.% (2.6-3.7 wt.%) at relevant pressures and temperatures, yielding the upper bound to the C content in the inner core. This concentration matches that in CI carbonaceous chondrites and corresponds to the average atomic mass in the range 49.3-51.0, in close agreement with inferences from Birch's law for the inner core. Similarly made estimates for the maximum hydrogen content are unrealistically high: 17-22 mol.% (0.4-0.5 wt.%), which corresponds to the average atomic mass of the core in the range 43.8-46.5. We conclude that carbon is a better candidate light alloying element than hydrogen.

Determining baseline element composition of lichens. I. Parmelia sulcata at Theodore Roosevelt national park, North Dakota

USGS Publications Warehouse

Gough, L.P.; Severson, R.C.; Jackson, L.L.

1988-01-01

Element-concentration baselines are given for Parmelia sulcata and associated soils. Parmelia chlorochroa was found sporadically and therefore only representative concentration ranges are reported for this species. Element data include (1) for lichens; Al, As, Ba, B, Ca, Cr, Cu, Fe, Hg, Mn, Ni, P, Sr, S, Ti, V, Y, and Zn; and (2) for soils: Al, Ba, Be, Ca, Cs, Cr, Cu, Fe, Hg, Mg, Mn, Ni, Nb, P, Pb, Sr, S, Ti, V, Y, and Zn. Very little (usually 7.2 km); thus, P sulcata is, in general, chemically similar throughout the park. This same uniformity was found for soil geochemistry. Numerous samples collected at close intervals would be required, therefore, to produce detailed element-concentration maps for P. sulcata and soils. No instances of elemental phytotoxic conditions were found; however, P. sulcata apparently possesses large concentrations of Ba, Cu, Fe, Pb, S, V, and possibly Zn.

Major and trace elements in igneous rocks from Apollo 15.

NASA Technical Reports Server (NTRS)

Helmke, P. A.; Blanchard, D. P.; Haskin, L. A.; Telander, K.; Weiss, C.; Jacobs, J. W.

1973-01-01

The concentrations of major and trace elements have been determined in igneous rocks from Apollo 15. All materials analyzed have typical depletions of Eu except for minerals separated from sample 15085. Four samples have concentrations of trace elements that are similar to those of KREEP. The samples of mare basalt from Apollo 15 have higher concentrations of FeO, MgO, Mn, and Cr and lower concentrations of CaO, Na2O, K2O, and rare-earth elements (REE) as compared to the samples of mare basalt from Apollos 11, 12, and 14. The samples can be divided into two groups on the basis of their normative compositions. One group is quartz normative and has low concentrations of FeO while the other is olivine normative and has high concentrations of FeO. The trace element data indicate that the samples of olivine normative basalt could be from different portions of a single lava flow.

The Diversity of Chemical Composition and the Effects on Stellar Evolution and Planetary Habitability

NASA Astrophysics Data System (ADS)

Truitt, Amanda R.

2017-08-01

I present a catalog of 1,794 stellar evolution models for solar-type and low-mass stars, which is intended to help characterize real host-stars of interest during the ongoing search for potentially habitable exoplanets. The main grid is composed of 904 tracks, for 0.5-1.2 M solar masses at scaled metallicity values of 0.1-1.5 Z solar masses and specific elemental abundance ratio values of 0.44-2.28 O/Fe solar masses, 0.58-1.72 C/Fe solar masses, 0.54-1.84 Mg/Fe solar masses, and 0.5-2.0 Ne/Fe solar masses. The catalog includes a small grid of late stage evolutionary tracks (25 models), as well as a grid of M-dwarf stars for 0.1-0.45 M solar masses (856 models). The time-dependent habitable zone evolution is calculated for each track, and is strongly dependent on stellar mass, effective temperature, and luminosity parameterizations. I have also developed a subroutine for the stellar evolution code TYCHO that implements a minimalist coupled model for estimating changes in the stellar X-ray luminosity, mass loss, rotational velocity, and magnetic activity over time; to test the utility of the updated code, I created a small grid (9 models) for solar-mass stars, with variations in rotational velocity and scaled metallicity. Including this kind of information in the catalog will ultimately allow for a more robust consideration of the long-term conditions that orbiting planets may experience. In order to gauge the true habitability potential of a given planetary system, it is extremely important to characterize the host-star's mass, specific chemical composition, and thus the timescale over which the star will evolve. It is also necessary to assess the likelihood that a planet found in the "instantaneous" habitable zone has actually had sufficient time to become "detectably" habitable. This catalog provides accurate stellar evolution predictions for a large collection of theoretical host-stars; the models are of particular utility in that they represent the real variation in stellar parameters that have been observed in nearby stars.

LSD (Landing System Development) Impact Simulation

NASA Astrophysics Data System (ADS)

Ullio, R.; Riva, N.; Pellegrino, P.; Deloo, P.

2012-07-01

In the frame of the Exploration Programs, a soft landing on the planet surface is foreseen. To ensure a successful final landing phase, a landing system by using leg tripod design landing legs with adequate crushable damping system was selected, capable of absorbing the residual velocities (vertical, horizontal and angular) at touch- down, insuring stability. TAS-I developed a numerical non linear dynamic methodology for the landing impact simulation of the Lander system by using a commercial explicit finite element analysis code (i.e. Altair RADIOSS). In this paper the most significant FE modeling approaches and results of the analytical simulation of landing impact are reported, especially with respect to the definition of leg dimensioning loads and the design update of selected parts (if necessary).

Enhanced thermal stability of Cu alloy films by strong interaction between Ni and Zr (or Fe)

NASA Astrophysics Data System (ADS)

Zheng, Yuehong; Li, Xiaona; Cheng, Xiaotian; Li, Zhuming; Liu, Yubo; Dong, Chuang

2018-04-01

Low resistivity, phase stability and nonreactivity with surrounding dielectrics are the key to the application of Cu to ultra-large-scale integrated circuits. Here, a stable solid solution cluster model was introduced to design the composition of barrierless Cu-Ni-Zr (or Fe) seed layers. The third elements Fe and Zr were dissolved into Cu via a second element Ni, which is soluble in both Cu and Zr (or Fe). The films were prepared by magnetron sputtering on the single-crystal p-Si (1 0 0) wafers. Since the diffusion characteristics of the alloying elements are different, the effects of the strong interaction between Ni and Zr (or Fe) on the film’s stability and resistivity were studied. The results showed that a proper addition of Zr-Ni (Zr/Ni  ⩽  0.6/12) into Cu could form a large negative lattice distortion, which inhibits Cu-Si interdiffusion and enhances the stability of Cu film. When Fe-Ni was co-added into Cu, the lattice distortion of Cu reached a lower value, 0.0029 Å  ⩽  |Δa|  ⩽  0.0046 Å, and the films showed poor stability. Therefore, when the model is applied to the composition design of the films, the strong interaction between the elements and the addition ratio should be taken into consideration.

Material flow analysis of NdFeB magnets for Denmark: a comprehensive waste flow sampling and analysis approach.

PubMed

Habib, Komal; Schibye, Peter Klausen; Vestbø, Andreas Peter; Dall, Ole; Wenzel, Henrik

2014-10-21

Neodymium-iron-boron (NdFeB) magnets have become highly desirable for modern hi-tech applications. These magnets, in general, contain two key rare earth elements (REEs), i.e., neodymium (Nd) and dysprosium (Dy), which are responsible for the very high strength of these magnets, allowing for considerable size and weight reduction in modern applications. This study aims to explore the current and future potential of a secondary supply of neodymium and dysprosium from recycling of NdFeB magnets. For this purpose, material flow analysis (MFA) has been carried out to perform the detailed mapping of stocks and flows of NdFeB magnets in Denmark. A novel element of this study is the value added to the traditionally practiced MFAs at national and/or global levels by complementing them with a comprehensive sampling and elemental analysis of NdFeB magnets, taken out from a sample of 157 different products representing 18 various product types. The results show that the current amount of neodymium and dysprosium in NdFeB magnets present in the Danish waste stream is only 3 and 0.2 Mg, respectively. However, this number is estimated to increase to 175 Mg of neodymium and 11.4 Mg of dysprosium by 2035. Nevertheless, efficient recovery of these elements from a very diverse electronic waste stream remains a logistic and economic challenge.

Effect of Silicon on Activity Coefficients of Siderophile Elements (P, Au, Pd, As, Ge, Sb, and In) in Liquid Fe, with Application to Core Formation

NASA Technical Reports Server (NTRS)

Righter, K.; Pando, K.; Danielson, L. R.; Humayun, M.; Righter, M.; Lapen, T.; Boujibar, A.

2016-01-01

Earth's core contains approximately 10 percent light elements that are likely a combination of S, C, Si, and O, with Si possibly being the most abundant. Si dissolved into Fe liquids can have a large effect on the magnitude of the activity coefficient of siderophile elements (SE) in Fe liquids, and thus the partitioning behavior of those elements between core and mantle. The effect of Si can be small such as for Ni and Co, or large such as for Mo, Ge, Sb, As. The effect of Si on many siderophile elements is unknown yet could be an important, and as yet unquantified, influence on the core-mantle partitioning of SE. Here we report new experiments designed to quantify the effect of Si on the partitioning of P, Au, Pd, and many other SE between metal and silicate melt. The results will be applied to Earth, for which we have excellent constraints on the mantle siderophile element concentrations.

Rare Earth Extraction from NdFeB Magnet Using a Closed-Loop Acid Process.

PubMed

Kitagawa, Jiro; Uemura, Ryohei

2017-08-14

There is considerable interest in extraction of rare earth elements from NdFeB magnets to enable recycling of these elements. In practical extraction methods using wet processes, the acid waste solution discharge is a problem that must be resolved to reduce the environmental impact of the process. Here, we present an encouraging demonstration of rare earth element extraction from a NdFeB magnet using a closed-loop hydrochloric acid (HCl)-based process. The extraction method is based on corrosion of the magnet in a pretreatment stage and a subsequent ionic liquid technique for Fe extraction from the HCl solution. The rare earth elements are then precipitated using oxalic acid. Triple extraction has been conducted and the recovery ratio of the rare earth elements from the solution is approximately 50% for each extraction process, as compared to almost 100% recovery when using a one-shot extraction process without the ionic liquid but with sufficient oxalic acid. Despite its reduced extraction efficiency, the proposed method with its small number of procedures at almost room temperature is still highly advantageous in terms of both cost and environmental friendliness. This study represents an initial step towards realization of a closed-loop acid process for recycling of rare earth elements.

Calibration-Free Laser-Induced Breakdown Spectroscopy (CF-LIBS) with Standard Reference Line for the Analysis of Stainless Steel.

PubMed

Fu, Hongbo; Dong, Fengzhong; Wang, Huadong; Jia, Junwei; Ni, Zhibo

2017-08-01

In this work, calibration-free laser-induced breakdown spectroscopy (CF-LIBS) is used to analyze a certified stainless steel sample. Due to self-absorption of the spectral lines from the major element Fe and the sparse lines of trace elements, it is usually not easy to construct the Boltzmann plots of all species. A standard reference line method is proposed here to solve this difficulty under the assumption of local thermodynamic equilibrium so that the same temperature value for all elements present into the plasma can be considered. Based on the concentration and rich spectral lines of Fe, the Stark broadening of Fe(I) 381.584 nm and Saha-Boltzmann plots of this element are used to calculate the electron density and the plasma temperature, respectively. In order to determine the plasma temperature accurately, which is seriously affected by self-absorption, a pre-selection procedure for eliminating those spectral lines with strong self-absorption is employed. Then, one spectral line of each element is selected to calculate its corresponding concentration. The results from the standard reference lines with and without self-absorption of Fe are compared. This method allows us to measure trace element content and effectively avoid the adverse effects due to self-absorption.

Levels of Essential Elements in Different Medicinal Plants Determined by Using Inductively Coupled Plasma Mass Spectrometry

PubMed Central

2018-01-01

The objective of this study was to investigate the content of essential elements in medicinal plants in the Kingdom of Saudi Arabia (KSA). Five different medical plants (mahareeb (Cymbopogon schoenanthus), sheeh (Artemisia vulgaris), harjal (Cynanchum argel delile), nabipoot (Equisetum arvense), and cafmariam (Vitex agnus-castus)) were collected from Madina city in the KSA. Five elements Fe, Mn, Zn, Cu, and Se were determined by using inductively coupled plasma mass spectrometry (ICP-MS). Fe levels were the highest and Se levels were the lowest in all plants. The range levels of all elements in all plants were as follows: Fe 193.4–1757.9, Mn 23.6–143.7, Zn 15.4–32.7, Se 0.13–0.92, and Cu 11.3–21.8 µg/g. Intakes of essential elements from the medical plants in infusion were calculated: Fe 4.6–13.4, Mn 6.7–123.2, Zn 7.0–42.7, Se 0.14–1.5, and Cu 1.5–5.0 µg/dose. The calculated intakes of essential elements for all plants did not exceed the daily intake set by the World Health Organization (WHO) and European Food Safety Authority (EFSA). These medicinal plants may be useful sources of essential elements, which are vital for health. PMID:29744234

Refining the chemical composition of the inner core with multicomponent alloys: from first-principles to thermodynamics and seismology

NASA Astrophysics Data System (ADS)

Caracas, R.; Asimow, P. D.; Wolf, A. S.; Harvey, J. P.; Martin, A.; Torrent, M.

2015-12-01

We compute the solubility limits of Si in the hexagonal-close packed (hcp) phase of iron using standard thermodynamical treatment of solid solutions with data obtained from first-principles calculations. For this, we consider the system with end-members hcp Fe and the B2 phase of FeSi. Si and Fe enter both structures in substitution of one another. The system is characterized by an immiscibility gap, which according to our results widens with pressure. At core conditions about 5 wt.% Si can be dissolved into the hcp phase of Fe. Comparatively there is much more Fe that can enter the FeSi B2 phase. In a second step we start with the hcp Fe-Si alloys and add the most probable light elements found in the core: H, C, O, and S. The light elements can enter the hcp structure either as interstitial impurities, in case of H, C, O, or in substitution of Fe, in case of S. We consider several insertion patterns with the light elements both adjacent and far apart. For each of these new phases we compute the elastic constants tensors and the seismic properties. Based on our theoretical results and the comparisons with PREM we discuss in detail the possible composition of the Earth's inner core, we rule out certain light elements, like H, and we show that the distribution pattern is not important. This is also the first time the elastic constants tensor is computed from lattice dynamics using the response function in the Planar Augmented Wavefunction approach of the Density Functional Theory [1]. [1] A. Martin, M. Torrent, R. Caracas, submitted (2015); A. Martin, PhD thesis (2015).

Orbital and maxillofacial computer aided surgery: patient-specific finite element models to predict surgical outcomes.

PubMed

Luboz, Vincent; Chabanas, Matthieu; Swider, Pascal; Payan, Yohan

2005-08-01

This paper addresses an important issue raised for the clinical relevance of Computer-Assisted Surgical applications, namely the methodology used to automatically build patient-specific finite element (FE) models of anatomical structures. From this perspective, a method is proposed, based on a technique called the mesh-matching method, followed by a process that corrects mesh irregularities. The mesh-matching algorithm generates patient-specific volume meshes from an existing generic model. The mesh regularization process is based on the Jacobian matrix transform related to the FE reference element and the current element. This method for generating patient-specific FE models is first applied to computer-assisted maxillofacial surgery, and more precisely, to the FE elastic modelling of patient facial soft tissues. For each patient, the planned bone osteotomies (mandible, maxilla, chin) are used as boundary conditions to deform the FE face model, in order to predict the aesthetic outcome of the surgery. Seven FE patient-specific models were successfully generated by our method. For one patient, the prediction of the FE model is qualitatively compared with the patient's post-operative appearance, measured from a computer tomography scan. Then, our methodology is applied to computer-assisted orbital surgery. It is, therefore, evaluated for the generation of 11 patient-specific FE poroelastic models of the orbital soft tissues. These models are used to predict the consequences of the surgical decompression of the orbit. More precisely, an average law is extrapolated from the simulations carried out for each patient model. This law links the size of the osteotomy (i.e. the surgical gesture) and the backward displacement of the eyeball (the consequence of the surgical gesture).

Trace elements in urban and suburban rainfall, Mersin, Northeastern Mediterranean

NASA Astrophysics Data System (ADS)

Özsoy, Türkan; Örnektekin, Sermin

2009-10-01

Spatial/temporal variabilities of rainwater constituents are examined based on soluble/insoluble trace elements, pH and electrical conductivity measurements in rainfall sampled during December 2003-May 2005 at two urban and two suburban sites in Mersin, an industrialized city of 850,000 inhabitants on the southern coast of Turkey. In the analyses, backward air mass trajectories for rainy days were used in addition to factor analyses, enrichment factors, phase distributions and correlations between trace elements. The pH varied from 4.8 to 8.5 with an average value of 6.2, reflecting a mainly alkaline regime. Mean concentrations of trace elements collected from urban and suburban sites are spatially variable. Based on the overall data, total concentrations of trace elements were ordered as Ca > Na > Fe > Al > Mg > K > Zn > Mn > Sr > Pb > Ni > Cr > Ba > Cu > Co > Cd. Mainly terrigeneous (Ca, Fe, Al) and, to a lesser extent, sea salt particles (Na, Mg) were shown to be the major source of trace elements. Excluding major cations, the solubilities of trace elements were found to be ordered as Sr > Zn > Ba > Mn > Cu > Ni > Cr > Fe > Al, confirming the lower solubility of crustal elements. Cd, Co and Pb were excluded from the above evaluation because of the low numbers of soluble samples allowing quantitative measurements. The solubilities of Al, Fe, Mn and particularly of Ni were found to be considerably lower than those reported for various sites around the world, most likely due to the effect of pH. During the entire sampling period, a total of 28 dust transport episodes associated with 31 red rain events were identified. Extremely high mean concentration ratios of Al (8.2), Fe (14.4) and Mn (13.1) were observed in red rain, compared to normal rain. The degree of this enhancement displayed a decrease from crustal to anthropogenic origin elements and the lowest enhancements were found for anthropogenic origin elements of Zn and Cd (both having a ratio of 1.1). Aerosol dust was found to be the main source of almost all analyzed elements in Mersin precipitation, regardless that they are crustal or anthropic derived elements. The magnitude of crustal source contribution to trace element budget of precipitation was at its highest levels for crustal originated elements, most probably due to much higher scavenging ratios of crustal elements compared to anthropogenic ones.

Fatigue and Damage Tolerance Analysis of a Hybrid Composite Tapered Flexbeam

NASA Technical Reports Server (NTRS)

Murri, Gretchen B.; Schaff, Jeffrey R.; Dobyns, Al

2001-01-01

The behavior of nonlinear tapered composite flexbeams under combined axial tension and cyclic bending loading was studied using coupon test specimens and finite element (FE) analyses. The flexbeams used a hybrid material system of graphite/epoxy and glass/epoxy and had internal dropped plies, dropped in an overlapping stepwise pattern. Two material configurations, differing only in the use of glass or graphite plies in the continuous plies near the midplane, were studied. Test specimens were cut from a full-size helicopter tail-rotor flexbeam and were tested in a hydraulic load frame under combined constant axialtension load and transverse cyclic bending loads. The first determination damage observed in the specimens occurred at the area around the tip of the outermost ply-drop group in the tapered region of the flexbeam, near the thick end. Delaminations grew slowly and stably, toward the thick end of the flexbeam, at the interfaces above and below the dropped-ply region. A 2D finite element model of the flexbeam was developed. The model was analyzed using a geometrically non-linear analysis with both the ANSYS and ABAQUS FE codes. The global responses of each analysis agreed well with the test results. The ANSYS model was used to calculate strain energy release rates (G) for delaminations initiating at two different ply-ending locations. The results showed that delaminations were more inclined to grow at the locations where they were observed in the test specimens. Both ANSYS and ABAQUS were used to calculate G values associated with delamination initiating at the observed location but growing in different interfaces, either above or below the ply-ending group toward the thick end, or toward the thin end from the tip of the resin pocket. The different analysis codes generated the same trends and comparable peak values, within 5-11 % for each delamination path. Both codes showed that delamination toward the thick region was largely mode II, and toward the thin region was predominantly mode I. The calculated peak G-values from either analysis predict delamination is most likely to occur along the same interface where it was observed in the test specimens. Calculated peak G values were used with material characterization data to calculate a curve relating the fatigue life of the specimens, N, to the applied transverse load, V, for a given constant axial load.

Nucleosynthesis by Type Ia Supernova for different Metallicity

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

Ohkubo, Takuya; Umeda, Hideyuki; Nomoto, Ken'ichi

2006-07-12

We calculate nucleosynthesis by type Ia supernova for various metallicity. We adopt two typical hydrodynamical models, carbon deflagration and delayed detonation. The two main points of this research are to see that (1)how the ejected mass of 56Ni changes and (2)how abundance of each element (especially Fe-group elements) is influenced by varying metallicity. We find that (1)56Ni mass changes about 15% in the range of Z = 0.001 - 0.05 and insufficient to explain all of the observed variety of SNe Ia peak luminosity, and (2)[Mn/Fe] and [Ni/Fe] show fairy dependence on metallicity (especially for delayed detonation model) while [Cr/Fe]more » or [{alpha}/Fe] do not.« less

Modelling of the material flow of Nd-Fe-B magnets under high temperature deformation via finite element simulation method

PubMed Central

Chen, Yen-Ju; Lee, Yen-I; Chang, Wen-Cheng; Hsiao, Po-Jen; You, Jr-Shian; Wang, Chun-Chieh; Wei, Chia-Min

2017-01-01

Abstract Hot deformation of Nd-Fe-B magnets has been studied for more than three decades. With a good combination of forming processing parameters, the remanence and (BH)max values of Nd-Fe-B magnets could be greatly increased due to the formation of anisotropic microstructures during hot deformation. In this work, a methodology is proposed for visualizing the material flow in hot-deformed Nd-Fe-B magnets via finite element simulation. Material flow in hot-deformed Nd-Fe-B magnets could be predicted by simulation, which fitted with experimental results. By utilizing this methodology, the correlation between strain distribution and magnetic properties enhancement could be better understood. PMID:28970869

Quantification of multiple elements in dried blood spot samples.

PubMed

Pedersen, Lise; Andersen-Ranberg, Karen; Hollergaard, Mads; Nybo, Mads

2017-08-01

Dried blood spots (DBS) is a unique matrix that offers advantages compared to conventional blood collection making it increasingly popular in large population studies. We here describe development and validation of a method to determine multiple elements in DBS. Elements were extracted from punches and analyzed using inductively coupled plasma-mass spectrometry (ICP-MS). The method was evaluated with quality controls with defined element concentration and blood spiked with elements to assess accuracy and imprecision. DBS element concentrations were compared with concentrations in venous blood. Samples with different hematocrit were spotted onto filter paper to assess hematocrit effect. The established method was precise and accurate for measurement of most elements in DBS. There was a significant but relatively weak correlation between measurement of the elements Mg, K, Fe, Cu, Zn, As and Se in DBS and venous whole blood. Hematocrit influenced the DBS element measurement, especially for K, Fe and Zn. Trace elements can be measured with high accuracy and low imprecision in DBS, but contribution of signal from the filter paper influences measurement of some elements present at low concentrations. Simultaneous measurement of K and Fe in DBS extracts may be used to estimate sample hematocrit. Copyright © 2017 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

Fission products detection in irradiated TRIGA fuel by means of gamma spectroscopy and MCNP calculation.

PubMed

Cagnazzo, M; Borio di Tigliole, A; Böck, H; Villa, M

2018-05-01

Aim of this work was the detection of fission products activity distribution along the axial dimension of irradiated fuel elements (FEs) at the TRIGA Mark II research reactor of the Technische Universität (TU) Wien. The activity distribution was measured by means of a customized fuel gamma scanning device, which includes a vertical lifting system to move the fuel rod along its vertical axis. For each investigated FE, a gamma spectrum measurement was performed along the vertical axis, with steps of 1 cm, in order to determine the axial distribution of the fission products. After the fuel elements underwent a relatively short cooling down period, different fission products were detected. The activity concentration was determined by calibrating the gamma detector with a standard calibration source of known activity and by MCNP6 simulations for the evaluation of self-absorption and geometric effects. Given the specific TRIGA fuel composition, a correction procedure is developed and used in this work for the measurement of the fission product Zr 95 . This measurement campaign is part of a more extended project aiming at the modelling of the TU Wien TRIGA reactor by means of different calculation codes (MCNP6, Serpent): the experimental results presented in this paper will be subsequently used for the benchmark of the models developed with the calculation codes. Copyright © 2018 Elsevier Ltd. All rights reserved.

Serial turbo trellis coded modulation using a serially concatenated coder

NASA Technical Reports Server (NTRS)

Divsalar, Dariush (Inventor); Dolinar, Samuel J. (Inventor); Pollara, Fabrizio (Inventor)

2010-01-01

Serial concatenated trellis coded modulation (SCTCM) includes an outer coder, an interleaver, a recursive inner coder and a mapping element. The outer coder receives data to be coded and produces outer coded data. The interleaver permutes the outer coded data to produce interleaved data. The recursive inner coder codes the interleaved data to produce inner coded data. The mapping element maps the inner coded data to a symbol. The recursive inner coder has a structure which facilitates iterative decoding of the symbols at a decoder system. The recursive inner coder and the mapping element are selected to maximize the effective free Euclidean distance of a trellis coded modulator formed from the recursive inner coder and the mapping element. The decoder system includes a demodulation unit, an inner SISO (soft-input soft-output) decoder, a deinterleaver, an outer SISO decoder, and an interleaver.

Alloying effects of Ni, Si, and S on the phase diagram and sound velocities of Fe under high pressures and high temperatures

NASA Astrophysics Data System (ADS)

Lin, J.; Fei, Y.; Sturhahn, W.; Zhao, J.; Mao, H.; Hemley, R.

2004-05-01

Iron-nickel is the most abundant constituent of the Earth's core. The amount of Ni in the core is about 5.5 wt%. Geophysical and cosmochemical studies suggest that the Earth's outer core also contains approximately 10% of light element(s) and a certain amount of light element(s) may be present in the inner core. Si and S are believed to be alloying light elements in the iron-rich planetary cores such as the Earth and Mars. Therefore, understanding the alloying effects of Ni, Si, and S on the phase diagram and physical properties of Fe under core conditions is crucial for geophysical and geochemical models of planetary interiors. The addition of Ni and Si does not appreciably change the compressibility of hcp-Fe under high pressures. Studies of the phase relations of Fe and Fe-Ni alloys indicate that Fe with up to 10 wt% Ni is likely to be in the hcp structure under inner core conditions. On the other hand, adding Si into Fe strongly stabilizes the bcc structure to much higher pressures and temperatures (Lin et al., 2002). We have also studied the sound velocities and magnetic properties of Fe0.92Ni0.08, Fe0.85Si0.15, and Fe3S alloys with nuclear resonant inelastic x-ray scattering and nuclear forward scattering up to 106 GPa, 70 GPa, and 57 GPa, respectively. The sound velocities of the alloys are obtained from the measured partial phonon density of states for 57Fe incorporated in the alloys. Addition of Ni slightly decreases the VP and VS of Fe under high pressures (Lin et al., 2003). Si or S alloyed with Fe increases the VP and VS under high pressures, which provides a better match to seismological data of the Earth's core. We note that the increase in the VP and VS of Fe0.85Si0.15 and Fe3S is mainly contributed from the density decrease of adding Si and S in iron. Time spectra of the nuclear forward scattering reveal that the most iron rich sulfide, Fe3S, undergoes a magnetic to non-magnetic transition at approximately 18 GPa from a low-pressure magnetically ordered state to a high-pressure non-magnetic ordered state. The magnetic transition significantly affects the elastic, thermodynamic, and vibrational properties of Fe3S. It is conceivable that the magnetic collapse of Fe3S may also affect the binary phase diagram of the iron-sulfur system, changing the solubility of sulfur in iron under higher pressures. Study of the non-magnetic phase is more relevant to understand the properties of the Fe3S under planetary core conditions where high pressures and high temperature ensure the non-magnetic ordering state, affecting the interpretation of the amount and properties of sulfur being in the planetary cores. If the Martian core is in the solid state containing 14.2 wt% sulfur, it is likely that the non-magnetic Fe3S phase is a dominant component and that our measured sound velocities of Fe3S can be used to understand the velocity profile in the Martian core.

Evaluation of elemental enrichments in surface sediments off southwestern Taiwan

NASA Astrophysics Data System (ADS)

Chen, Chen-Tung; Kandasamy, Selvaraj

2008-05-01

Surface slices of 20 sediment cores, off southwestern Taiwan, and bed sediment of River Kaoping were measured for major and trace elements (Al, As, Ca, Cd, Cl, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, Pb, S, Si, Ti, V, and Zn) to evaluate the geochemical processes responsible for their distribution, including elemental contamination. Major element/Al ratio and mean grain size indicate quartz-dominated, coarse grained sediments that likely derived from sedimentary rocks of Taiwan and upper crust of Yangtze Craton. Bi-plot of SiO2 versus Fe2O{3/T} suggests the possible iron enrichment in sediments of slag dumping sites. Highest concentrations of Cr, Mn, P, S, and Zn found in sediments of dumping sites support this. Correlation analysis shows dual associations, detrital and organic carbon, for Cr, P, S, and V with the latter association typical for sediments in dumping sites. Normalization of trace elements to Al indicates high enrichment factors (>2) for As, Cd, Pb, and Zn, revealing contamination. Factor analysis extracted four geochemical associations with the principal factor accounted for 25.1% of the total variance and identifies the combined effects of dumped iron and steel slag-induced C-S-Fe relationship owing to authigenic precipitation of Fe-Mn oxyhydroxides and/or metal sulfides, and organic matter complexation of Fe, Mn, Ca, Cr, P, and V. Factors 2, 3, and 4 reveal detrital association (Ti, Al, Ni, Pb, Cu, and V), effect of sea salt (Cl, Mg, Na, and K) and anthropogenic component (As and Zn)-carbonate link, respectively, in the investigated sediments.

Abundances in metal-rich stars. Detailed abundance analysis of 47 G and K dwarf stars with [Me/H] > 0.10 dex

NASA Astrophysics Data System (ADS)

Feltzing, S.; Gustafsson, B.

1998-04-01

We have derived elemental abundances of O, Na, Mg, Al, Si, Ca, Ti, Cr, Mn, Fe, Co, Ni as well as for a number of s-elements for 47 G and K dwarf, with [Me/H]>0.1 dex. The selection of stars was based on their kinematics as well as on their uvby-beta photometry. One sample of stars on rather eccentric orbits traces the chemical evolution interior to the solar orbit and another, on circular orbits, the evolution around the solar orbit. A few Extreme Population I stars were included in the latter sample. The stars have -0.1 dex < [Fe/H] < 0.42 dex. The spectroscopic [Fe/H] correlate well with the [Me/H] derived from uvby-beta photometry. We find that the elemental abundances of Mg, Al, Si, Ca, Ti, Cr and Ni all follow [Fe/H]. Our data put further constraints on models of galactic chemical evolution, in particular of Cr, Mn and Co which have not previously been studied for dwarf stars with [Me/H] >0.1 dex. The increase in [Na/Fe] and [Al/Fe] as a function of [Fe/H] found previously by \\cite[Edvardsson et al. (1993a)]{Edv93} has been confirmed for [Na/Fe]. This upturning relation, and the scatter around it, are shown not to be due to a mixture of populations with different mean distances to the galactic centre. We do not confirm the same trend for aluminium, which is somewhat surprising since both these elements are thought to be produced in the same environments in the pre-supernova stars. Nor have we been able to trace any tendency for relative abundances of O, Si, and Ti relative to Fe to vary with the stellar velocities, i.e. the stars present mean distance to the galactic centre. These results imply that there is no significant difference in the chemical evolution of the different stellar populations for stars with [Me/H]>0.1 dex. We find that [O/Fe] continue to decline with increasing [Fe/H] and that oxygen and europium correlate well. However [Si/Fe] and [Ca/Fe] seem to stay constant. A real (``cosmic'') scatter in [Ti/Fe] at given [Fe/H] is suggested as well as a decreasing abundance of the s-elements relative to iron for the most metal-rich dwarf stars. We discuss our results in the context of recent models of galactic chemical evolution. In our sample we have included a few very metal rich stars, sometimes called SMR (super metal rich) stars. We find these stars to be among the most iron-rich in our sample but far from as metal-rich as indicated by their photometric metallicities. SMR stars on highly eccentric orbits, alleged to trace the evolution of the chemical evolution in the galactic Bulge, have previously been found overabundant in O, Mg and Si. We have included three such stars from the study by \\cite[Barbuy & Grenon (1990)]{Bar90}. We find them to be less metal rich and the other elemental abundances remain puzzling. Detailed spectroscopic abundance analyses of K dwarf stars are rare. Our study includes 5 K dwarf stars and has revealed what appears to be a striking example of overionization. The overionization is especially prominent for Ca, Cr and Fe. The origin of this apparent overionization is not clear and we discuss different explanations in some detail. Based on observations at the McDonald Observatory.

Trace of heavy metals in maternal and umbilical cord blood samples in association with birth outcomes in Baghdad, Iraq

NASA Astrophysics Data System (ADS)

Hasan Rhaif Al-Sahlanee, Mayyadah; Maizan Ramli, Ramzun; Abdul Hassan Ali, Miami; Fadhil Tawfiq, Nada; Zahirah Noor Azman, Nurul; Abdul Rahman, Azhar; Shahrim Mustafa, Iskandar; Noor Ashikin Nik Abdul Razak, Nik; Zakiah Yahaya, Nor; Mohammed Al-Marri, Hana; Syuhada Ayob, Nur; Zakaria, Nabela

2017-10-01

Trace elements are essential nutritional components in humans and inconvenient tissue content that have a significant influence on infant size. The aim of this study is to evaluate the effects of concentration of elements (uranium (U), lead (Pb) and iron (Fe)) and absorption of Pb and Fe on maternal and umbilical cord blood samples. The concentration and absorption of Pb and Fe in blood samples were determined by using atomic absorption spectrophotometry device, while the uranium concentration was determined by using CR-39 detector. Fifty women of age 16-44 years are involved in this study. Results show that the maximum and minimum values of both concentration and absorption in the maternal samples were for Pb and Fe, respectively. In addition, for umbilical cord, the maximum values of concentration and absorption were for Fe and the minimum concentration and absorption were for U and Pb, respectively. A significant correlation between maternal and umbilical cord blood samples was found. This indicates that the Pb, U and Fe elements can easily transfer from maternal to the fetal body which impacts the growth of fetus.

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

Jacobson, Heather R.; Pilachowski, Catherine A.; Friel, Eileen D., E-mail: jacob189@msu.edu, E-mail: catyp@astro.indiana.edu, E-mail: edfriel@mac.com

We present a detailed chemical abundance study of evolved stars in 10 open clusters based on Hydra multi-object echelle spectra obtained with the WIYN 3.5 m telescope. From an analysis of both equivalent widths and spectrum synthesis, abundances have been determined for the elements Fe, Na, O, Mg, Si, Ca, Ti, Ni, Zr, and for two of the 10 clusters, Al and Cr. To our knowledge, this is the first detailed abundance analysis for clusters NGC 1245, NGC 2194, NGC 2355, and NGC 2425. These 10 clusters were selected for analysis because they span a Galactocentric distance range R{sub gc}more » {approx} 9-13 kpc, the approximate location of the transition between the inner and outer disks. Combined with cluster samples from our previous work and those of other studies in the literature, we explore abundance trends as a function of cluster R{sub gc}, age, and [Fe/H]. As found previously by us and other studies, the [Fe/H] distribution appears to decrease with increasing R{sub gc} to a distance of {approx}12 kpc and then flattens to a roughly constant value in the outer disk. Cluster average element [X/Fe] ratios appear to be independent of R{sub gc}, although the picture for [O/Fe] is more complicated with a clear trend of [O/Fe] with [Fe/H] and sample incompleteness. Other than oxygen, no other element [X/Fe] exhibits a clear trend with [Fe/H]; likewise, there does not appear to be any strong correlation between abundance and cluster age. We divided clusters into different age bins to explore temporal variations in the radial element distributions. The radial metallicity gradient appears to have flattened slightly as a function of time, as found by other studies. There is also some indication that the transition from the inner disk metallicity gradient to the {approx}constant [Fe/H] distribution of the outer disk occurs at different Galactocentric radii for different age bins. However, interpretation of the time evolution of radial abundance distributions is complicated by the unequal R{sub gc} and [Fe/H] ranges spanned by clusters in different age bins.« less

So Tell Me What You Want: A Comparison of FE College and Other Post-16 Students' Aspirations

ERIC Educational Resources Information Center

Baird, Jo-Anne; Rose, Jo; McWhirter, Alison

2012-01-01

This study compares the aspirations of students in further education (FE) colleges and non-FE post-compulsory settings. Within the context of a survey about their education, 928 students across 26 institutions were asked what their "hopes, goals and plans" were, with space for five open responses. Coding of responses was based upon…

Galactic evolution of oxygen. OH lines in 3D hydrodynamical model atmospheres

NASA Astrophysics Data System (ADS)

González Hernández, J. I.; Bonifacio, P.; Ludwig, H.-G.; Caffau, E.; Behara, N. T.; Freytag, B.

2010-09-01

Context. Oxygen is the third most common element in the Universe. The measurement of oxygen lines in metal-poor unevolved stars, in particular near-UV OH lines, can provide invaluable information about the properties of the Early Galaxy. Aims: Near-UV OH lines constitute an important tool to derive oxygen abundances in metal-poor dwarf stars. Therefore, it is important to correctly model the line formation of OH lines, especially in metal-poor stars, where 3D hydrodynamical models commonly predict cooler temperatures than plane-parallel hydrostatic models in the upper photosphere. Methods: We have made use of a grid of 52 3D hydrodynamical model atmospheres for dwarf stars computed with the code CO5BOLD, extracted from the more extended CIFIST grid. The 52 models cover the effective temperature range 5000-6500 K, the surface gravity range 3.5-4.5 and the metallicity range -3 < [Fe/H] < 0. Results: We determine 3D-LTE abundance corrections in all 52 3D models for several OH lines and ion{Fe}{i} lines of different excitation potentials. These 3D-LTE corrections are generally negative and reach values of roughly -1 dex (for the OH 3167 with excitation potential of approximately 1 eV) for the higher temperatures and surface gravities. Conclusions: We apply these 3D-LTE corrections to the individual O abundances derived from OH lines of a sample the metal-poor dwarf stars reported in Israelian et al. (1998, ApJ, 507, 805), Israelian et al. (2001, ApJ, 551, 833) and Boesgaard et al. (1999, AJ, 117, 492) by interpolating the stellar parameters of the dwarfs in the grid of 3D-LTE corrections. The new 3D-LTE [O/Fe] ratio still keeps a similar trend as the 1D-LTE, i.e., increasing towards lower [Fe/H] values. We applied 1D-NLTE corrections to 3D ion{Fe}{i} abundances and still see an increasing [O/Fe] ratio towards lower metallicites. However, the Galactic [O/Fe] ratio must be revisited once 3D-NLTE corrections become available for OH and Fe lines for a grid of 3D hydrodynamical model atmospheres.

Trace Elements and Carbon and Nitrogen Stable Isotopes in Organisms from a Tropical Coastal Lagoon

PubMed Central

van Hattum, B.; de Boer, J.; van Bodegom, P. M.; Rezende, C. E.; Salomons, W.

2010-01-01

Trace elements (Fe, Mn, Al, Zn, Cr, Cu, Ni, Pb, Cd, Hg, and As) and stable isotope ratios (δ13C and δ15N) were analyzed in sediments, invertebrates, and fishes from a tropical coastal lagoon influenced by iron ore mining and processing activities to assess the differences in trace element accumulation patterns among species and to investigate relations with trophic levels of the organisms involved. Overall significant negative relations between trophic level (given by 15N) and trace element concentrations in gastropods and crustaceans showed differences in internal controls of trace element accumulation among the species of different trophic positions, leading to trace element dilution. Generally, no significant relation between δ15N and trace element concentrations was observed among fish species, probably due to omnivory in a number of species as well as fast growth. Trace element accumulation was observed in the fish tissues, with higher levels of most trace elements found in liver compared with muscle and gill. Levels of Fe, Mn, Al, and Hg in invertebrates, and Fe and Cu in fish livers, were comparable with levels in organisms and tissues from other contaminated areas. Trace element levels in fish muscle were below the international safety baseline standards for human consumption. PMID:20217062

Trace elements and carbon and nitrogen stable isotopes in organisms from a tropical coastal lagoon.

PubMed

Pereira, A A; van Hattum, B; de Boer, J; van Bodegom, P M; Rezende, C E; Salomons, W

2010-10-01

Trace elements (Fe, Mn, Al, Zn, Cr, Cu, Ni, Pb, Cd, Hg, and As) and stable isotope ratios (delta(13)C and delta(15)N) were analyzed in sediments, invertebrates, and fishes from a tropical coastal lagoon influenced by iron ore mining and processing activities to assess the differences in trace element accumulation patterns among species and to investigate relations with trophic levels of the organisms involved. Overall significant negative relations between trophic level (given by (15)N) and trace element concentrations in gastropods and crustaceans showed differences in internal controls of trace element accumulation among the species of different trophic positions, leading to trace element dilution. Generally, no significant relation between delta(15)N and trace element concentrations was observed among fish species, probably due to omnivory in a number of species as well as fast growth. Trace element accumulation was observed in the fish tissues, with higher levels of most trace elements found in liver compared with muscle and gill. Levels of Fe, Mn, Al, and Hg in invertebrates, and Fe and Cu in fish livers, were comparable with levels in organisms and tissues from other contaminated areas. Trace element levels in fish muscle were below the international safety baseline standards for human consumption.

Spectroscopic Study of HD 179821 (IRAS 19114+0002): Proto-Planetary Nebula or Supergiant?

NASA Technical Reports Server (NTRS)

Reddy, B. E.; Hrivnak, Bruce J.

1999-01-01

A detailed chemical composition analysis of the bright post-AGB candidate HD 179821 (IRAS 19114 + 0002) is presented. The LTE analysis, based on high-resolution (R approximately equal 50,000) and high-quality (S/N approximately equal 300) spectra, yields atmospheric parameters T(sub eff) = 6750 K, log g = 0.5, and xi(sub t) = 5.25 km/s. The elemental abundance results of HD 179821 are found to be [Fe/H] = -0.1, [C/Fe] = +0.2, [N/Fe] = +1.3, [O/Fe] = +0.2, [alpha-process/Fe] = +0.5, and [s-process/Fe] = +0.4. These values clearly differ from the elemental abundances of Population I F supergiants. The C, N, and O abundances and the total CNO abundance value relative to Fe, [C+N+O/Fe] = +0.5, indicate that the photosphere of HD 179821 is contaminated with both the H- and He-burning products of the AGB phase. The evidence for He burning through the 3.alpha process and deep AGB mixing also comes from the observed overabundances of s-process elements. Remarkably, the abundance of the element Na is found to be very large, [Na/Fe] = +0.9. The ratio O/C = 2.6 indicates that the atmosphere is oxygen rich. The results of this abundance study support the argument that HD 179821 is a proto-planetary nebula,. probably with an intermediate-mass progenitor. However, the strength of the O I triplet lines at 7774 A and the distance derived from the interstellar Na I D1 and D2 components imply that the star is a luminous object (M(sub bol) approximately -8.9 +/- 1) and thus a massive supergiant. Thus, while this study contributes important new observational results for this star, an unambiguous determination of its evolutionary status has yet to be achieved.

Rates of As and trace-element mobilization caused by Fe reduction in mixed BTEX–ethanol experimental plumes

USGS Publications Warehouse

Ziegler, Brady A.; McGuire, Jennifer T.; Cozzarelli, Isabelle M.

2015-01-01

Biodegradation of organic matter, including petroleum-based fuels and biofuels, can create undesired secondary water-quality effects. Trace elements, especially arsenic (As), have strong adsorption affinities for Fe(III) (oxyhydr)-oxides and can be released to groundwater during Fe-reducing biodegradation. We investigated the mobilization of naturally occurring As, cobalt (Co), chromium (Cr), and nickel (Ni) from wetland sediments caused by the introduction of benzene, toluene, ethylbenzene, and xylenes (BTEX) and ethanol mixtures under iron- and nitrate-reducing conditions, using in situ push–pull tests. When BTEX alone was added, results showed simultaneous onset and similar rates of Fe reduction and As mobilization. In the presence of ethanol, the maximum rates of As release and Fe reduction were higher, the time to onset of reaction was decreased, and the rates occurred in multiple stages that reflected additional processes. The concentration of As increased from <1 μg/L to a maximum of 99 μg/L, exceeding the 10 μg/L limit for drinking water. Mobilization of Co, Cr, and Ni was observed in association with ethanol biodegradation but not with BTEX. These results demonstrate the potential for trace-element contamination of drinking water during biodegradation and highlight the importance of monitoring trace elements at natural and enhanced attenuation sites.

Assessment of function-graded materials as fracture fixation bone-plates under combined loading conditions using finite element modelling.

PubMed

Fouad, H

2011-05-01

In previous work by Fouad (Medical Engineering and Physics 2010 [23]), 3D finite element (FE) models for fractured bones with function-graded (FG) bone-plates and traditional bone-plates made of stainless steel (SS) and titanium (Ti) alloy were examined under compressive loading conditions using the ABAQUS Code. In this study, the effects of the presence of the torsional load in addition to the compressive load on the predicted stresses of the fracture fixation bone-plate system are examined at different healing stages. The effects on the stress on the fracture site when using contacted and non-contacted bone-plate systems are also studied. The FE modelling results indicate that the torsional load has significant effects on the resultant stress on the fracture fixation bone-plate system, which should be taken into consideration during the design and the analysis. The results also show that the stress shielding at the fracture site decreases significantly when using FG bone-plates compared to Ti alloy or SS bone-plates. The presence of a gap between the bone and the plate results in a remarkable reduction in bone stress shielding at the fracture site. Therefore, the significant effects of using an FG bone-plate with a gap and the presence of torsional load on the resultant stress on the fracture fixation bone-plate system should be taken into consideration. Copyright © 2010 IPEM. Published by Elsevier Ltd. All rights reserved.

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

Gong, Ke; Xu, Fei; Grunewald, Jonathan B.

The rapid growth of intermittent renewable energy (e.g., wind and solar) demands low-cost and large-scale energy storage systems for smooth and reliable power output, where redox-flow batteries (RFBs) could find their niche. In this work, we introduce the first all-soluble all-iron RFB based on iron as the same redox-active element but with different coordination chemistries in alkaline aqueous system. The adoption of the same redox-active element largely alleviates the challenging problem of cross-contamination of metal ions in RFBs that use two redox-active elements. An all-soluble all-iron RFB is constructed by combining an iron–triethanolamine redox pair (i.e., [Fe(TEOA)OH] –/[Fe(TEOA)(OH)] 2–) andmore » an iron–cyanide redox pair (i.e., Fe(CN) 6 3–/Fe(CN) 6 4–), creating 1.34 V of formal cell voltage. Furthermore, good performance and stability have been demonstrated, after addressing some challenges, including the crossover of the ligand agent. As exemplified by the all-soluble all-iron flow battery, combining redox pairs of the same redox-active element with different coordination chemistries could extend the spectrum of RFBs.« less

Computer-Aided Design of Manufacturing Chain Based on Closed Die Forging for Hardly Deformable Cu-Based Alloys

NASA Astrophysics Data System (ADS)

Pietrzyk, Maciej; Kuziak, Roman; Pidvysots'kyy, Valeriy; Nowak, Jarosław; Węglarczyk, Stanisław; Drozdowski, Krzysztof

2013-07-01

Two copper-based alloys were considered, Cu-1 pct Cr and Cu-0.7 pct Cr-1 pct Si-2 pct Ni. The thermal, electrical, and mechanical properties of these alloys are given in the paper and compared to pure copper and steel. The role of aging and precipitation kinetics in hardening of the alloys is discussed based upon the developed model. Results of plastometric tests performed at various temperatures and various strain rates are presented. The effect of the initial microstructure on the flow stress was investigated. Rheologic models for the alloys were developed. A finite element (FE) model based on the Norton-Hoff visco-plastic flow rule was applied to the simulation of forging of the alloys. Analysis of the die wear for various processes of hot and cold forging is presented as well. A microstructure evolution model was implemented into the FE code, and the microstructure and mechanical properties of final products were predicted. Various variants of the manufacturing cycles were considered. These include different preheating schedules, hot forging, cold forging, and aging. All variants were simulated using the FE method and loads, die filling, tool wear, and mechanical properties of products were predicted. Three variants giving the best combination of forging parameters were selected and industrial trials were performed. The best manufacturing technology for the copper-based alloys is proposed.

PRELIMINARY EVALUATION OF FeCrAl CLADDING AND U-Si FUEL FOR ACCIDENT TOLERANT FUEL CONCEPTS

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

Hales, J. D.; Gamble, K. A.

2015-09-01

Since the accident at the Fukushima Daiichi Nuclear Power Station, enhancing the accident tolerance of light water reactors (LWRs) has become an important research topic. In particular, the community is actively developing enhanced fuels and cladding for LWRs to improve safety in the event of accidents in the reactor or spent fuel pools. Fuels with enhanced accident tolerance are those that, in comparison with the standard UO2-zirconium alloy system, can tolerate loss of active cooling in the reactor core for a considerably longer time period during design-basis and beyond design-basis events while maintaining or improving the fuel performance during normalmore » operations and operational transients. This paper presents early work in developing thermal and mechanical models for two materials that may have promise: U-Si for fuel, and FeCrAl for cladding. These materials would not necessarily be used together in the same fuel system, but individually have promising characteristics. BISON, the finite element-based fuel performance code in development at Idaho National Laboratory, was used to compare results from normal operation conditions with Zr-4/UO2 behavior. In addition, sensitivity studies are presented for evaluating the relative importance of material parameters such as ductility and thermal conductivity in FeCrAl and U-Si in order to provide guidance on future experiments for these materials.« less

The Spectroscopic Evolution of Nova Cygni 1992

NASA Astrophysics Data System (ADS)

Moro-Martin, A.; Garnavich, P. M.; Noriega-Crespo, A.; Alpert, A.

1996-12-01

Optical spectroscopic observations of Nova Cygni 1992 spanning 4 years are modeled in this study. The data were obtained primarily with the DAO 1.8m telescope and cover a wavelength range from ~ 3200 - 8000 Angstroms. The observations begin on May 92 (85 days after the outburst) and end on June 1996, i.e. during most of the optically thin evolutionary phase. The spectra were modeled in a relatively straightforward way by using the flux predicted by a photoionization code [1] for most of the emission lines (down to 0.1% of Hβ ) and transforming these numbers into a synthetic spectrum. There are, however, significant differences in the detailed procedure in comparison with similar works [2]. First, the photoionization models were run at a fixed abundance value for the most prominent elements (i.e. H, He, C, O, N, Ne, Fe, etc) over the entire time sequence. Second, the brightest lines, e.g. [Ne V], [Ne III], [O III] and the Balmer lines, were initially used as guide to match the observations. The rest of the spectra, which includes the fainter lines, were then directly predicted by the photoionization code. Considering the complicated structure of the shell [3], the lack of well defined values of its gas density and our limited knowledge of the time evolution of the surface temperature of the photoionization source, the comparison between models and observations agrees remarkably well. It was found that the time evolution of some of the Iron coronal lines, [Fe VII] 6087 Angstroms and [Fe X] 6374 Angstroms, closely follows that of the X-rays [4]. [1] Ferland, G.J 1993, CLOUDY, U. of Kentucky Dept. Phys & Astr. Internal Report. [2] Austin et al. 1992, AJ, 111, 869 [3] Paresce, Livio, Hack & Korista (1995) A&A, 299, 823 [4] Krautter et al. (1996), ApJ, 456, 788

Palindromic repetitive DNA elements with coding potential in Methanocaldococcus jannaschii.

PubMed

Suyama, Mikita; Lathe, Warren C; Bork, Peer

2005-10-10

We have identified 141 novel palindromic repetitive elements in the genome of euryarchaeon Methanocaldococcus jannaschii. The total length of these elements is 14.3kb, which corresponds to 0.9% of the total genomic sequence and 6.3% of all extragenic regions. The elements can be divided into three groups (MJRE1-3) based on the sequence similarity. The low sequence identity within each of the groups suggests rather old origin of these elements in M. jannaschii. Three MJRE2 elements were located within the protein coding regions without disrupting the coding potential of the host genes, indicating that insertion of repeats might be a widespread mechanism to enhance sequence diversity in coding regions.

Abundance patterns of the light neutron-capture elements in very and extremely metal-poor stars

NASA Astrophysics Data System (ADS)

Spite, F.; Spite, M.; Barbuy, B.; Bonifacio, P.; Caffau, E.; François, P.

2018-03-01

Aims: The abundance patterns of the neutron-capture elements in metal-poor stars provide a unique record of the nucleosynthesis products of the earlier massive primitive objects. Methods: We measured new abundances of so-called light neutron-capture of first peak elements using local thermodynamic equilibrium (LTE) 1D analysis; this analysis resulted in a sample of 11 very metal-poor stars, from [Fe/H] = -2.5 to [Fe/H] = -3.4, and one carbon-rich star, CS 22949-037 with [Fe/H] = -4.0. The abundances were compared to those observed in two classical metal-poor stars: the typical r-rich star CS 31082-001 ([Eu/Fe] > +1.0) and the r-poor star HD 122563 ([Eu/Fe] < 0.0), which are known to present a strong enrichment of the first peak neutron-capture elements relative to the second peak. Results: Within the first peak, the abundances are well correlated in analogy to the well-known correlation inside the abundances of the second-peak elements. In contrast, there is no correlation between any first peak element with any second peak element. We show that the scatter of the ratio of the first peak abundance over second peak abundance increases when the mean abundance of the second peak elements decreases from r-rich to r-poor stars. We found two new r-poor stars that are very similar to HD 122563. A third r-poor star, CS 22897-008, is even more extreme; this star shows the most extreme example of first peak elements enrichment to date. On the contrary, another r-poor star (BD-18 5550) has a pattern of first peak elements that is similar to the typical r-rich stars CS 31082-001, however this star has some Mo enrichment. Conclusions: The distribution of the neutron-capture elements in our very metal-poor stars can be understood as the combination of at least two mechanisms: one that enriches the forming stars cloud homogeneously through the main r-process and leads to an element pattern similar to the r-rich stars, such as CS 31082-001; and another that forms mainly lighter, first peak elements. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programme 165.N-0276(A), (PI R.Cayrel).

Extreme Ultraviolet Emission Lines of Iron Fe XI-XIII

NASA Astrophysics Data System (ADS)

Lepson, Jaan; Beiersdorfer, P.; Brown, G. V.; Liedahl, D. A.; Brickhouse, N. S.; Dupree, A. K.

2013-04-01

The extreme ultraviolet (EUV) spectral region (ca. 20--300 Å) is rich in emission lines from low- to mid-Z ions, particularly from the middle charge states of iron. Many of these emission lines are important diagnostics for astrophysical plasmas, providing information on properties such as elemental abundance, temperature, density, and even magnetic field strength. In recent years, strides have been made to understand the complexity of the atomic levels of the ions that emit the lines that contribute to the richness of the EUV region. Laboratory measurements have been made to verify and benchmark the lines. Here, we present laboratory measurements of Fe XI, Fe XII, and Fe XIII between 40-140 Å. The measurements were made at the Lawrence Livermore electron beam ion trap (EBIT) facility, which has been optimized for laboratory astrophysics, and which allows us to select specific charge states of iron to help line identification. We also present new calculations by the Hebrew University - Lawrence Livermore Atomic Code (HULLAC), which we also utilized for line identification. We found that HULLAC does a creditable job of reproducing the forest of lines we observed in the EBIT spectra, although line positions are in need of adjustment, and line intensities often differed from those observed. We identify or confirm a number of new lines for these charge states. This work was supported by the NASA Solar and Heliospheric Program under Contract NNH10AN31I and the DOE General Plasma Science program. Work was performed in part under the auspices of the Department of Energy by Lawrence Livermore National Laboratory under Contract DEAC52-07NA27344.

Geochemical features of sulfides from the Deyin-1 hydrothermal field at the southern Mid-Atlantic Ridge near 15°S

NASA Astrophysics Data System (ADS)

Wang, Shujie; Li, Huaiming; Zhai, Shikui; Yu, Zenghui; Cai, Zongwei

2017-12-01

In this study, geochemical compositions of elements in sulfide samples collected from the Deyin-1 hydrothermal field near the 15°S southern Mid-Atlantic Ridge (SMAR) were analyzed by the X-ray fluorescence spectrometry (XRF) and inductively coupled plasma mass spectrometry (ICP-MS) to examine the enrichment regulations of ore-forming elements and hydrothermal mineralization. These sulfide precipitates can be classified macroscopically into three types: Fe-rich sulfide, Fe-Cu-rich sulfide and Fe-Zn-rich sulfide, and are characterized by the enrichment of base metal elements along with a sequence of Fe>Zn>Cu. Compared with sulfides from other hydrothermal fields on MAR, Zn concentrations of sulfides in the research area are significantly high, while Cu concentrations are relatively low. For all major, trace or rare-earth elements (REE), their concentrations and related characteristic parameters exhibit significant variations (up to one or two orders of magnitude), which indicates the sulfides from different hydrothermal vents or even a same station were formed at different stages of hydrothermal mineralization, and suggests the variations of chemical compositions of the hydrothermal fluid with respect to time. The hydrothermal temperatures of sulfides precipitation decreased gradually from station TVG10 (st.TVG10) to st.TVG12, and to st.TVG11, indicating that the precipitation of hydrothermal sulfides is subjected to conditions changed from high temperature to low temperature, and that the hydrothermal activity of study area was at the late stage of a general trend of evolution from strong to weak. The abnormally low concentrations of REE in sulfides and their similar chondrite-normalized REE patterns show that REEs in all sulfides were derived from a same source, but underwent different processes of migration or enrichment, or sulfides were formed at different stages of hydrothermal mineralization. The sulfides collected from the active hydrothermal vent were mainly attributed to precipitating directly from the hydrothermal fluid, while those collected from the extinct hydrothermal chimney might have already been altered by the seawater. Generally, ore-forming elements in the sulfides can be divided into three groups: Fe-based element group, Cu-based element group and Zn-based element group. The first group includes Fe, Mn, Cr, Mo, Sn, Rb and bio-enriching elements, such as P and Si, reflecting the similar characteristics to Fe in the study area. And the second group contains Cu, W, Co, Se, Te and Bi, suggesting the similar behavior with Cu. Moreover, the third group includes Zn, Hf, Hg, Cd, Ta, Ga, Pb, As, Ag, Ni and Sb, which indicates the geochemical characteristics of most dispersed trace elements controlled by Zn-bearing minerals to some extent.

Fe-FeO and Fe-Fe3C melting relations at Earth's core-mantle boundary conditions: Implications for a volatile-rich or oxygen-rich core

NASA Astrophysics Data System (ADS)

Morard, G.; Andrault, D.; Antonangeli, D.; Nakajima, Y.; Auzende, A. L.; Boulard, E.; Cervera, S.; Clark, A.; Lord, O. T.; Siebert, J.; Svitlyk, V.; Garbarino, G.; Mezouar, M.

2017-09-01

Eutectic melting temperatures in the Fe-FeO and Fe-Fe3C systems have been determined up to 150 GPa. Melting criteria include observation of a diffuse scattering signal by in situ X-Ray diffraction, and textural characterisation of recovered samples. In addition, compositions of eutectic liquids have been established by combining in situ Rietveld analyses with ex situ chemical analyses. Gathering these new results together with previous reports on Fe-S and Fe-Si systems allow us to discuss the specific effect of each light element (Si, S, O, C) on the melting properties of the outer core. Crystallization temperatures of Si-rich core compositional models are too high to be compatible with the absence of extensive mantle melting at the core-mantle boundary (CMB) and significant amounts of volatile elements such as S and/or C (>5 at%, corresponding to >2 wt%), or a large amount of O (>15 at% corresponding to ∼5 wt%) are required to reduce the crystallisation temperature of the core material below that of a peridotitic lower mantle.

Automation of a DXA-based finite element tool for clinical assessment of hip fracture risk.

PubMed

Luo, Yunhua; Ahmed, Sharif; Leslie, William D

2018-03-01

Finite element analysis of medical images is a promising tool for assessing hip fracture risk. Although a number of finite element models have been developed for this purpose, none of them have been routinely used in clinic. The main reason is that the computer programs that implement the finite element models have not been completely automated, and heavy training is required before clinicians can effectively use them. By using information embedded in clinical dual energy X-ray absorptiometry (DXA), we completely automated a DXA-based finite element (FE) model that we previously developed for predicting hip fracture risk. The automated FE tool can be run as a standalone computer program with the subject's raw hip DXA image as input. The automated FE tool had greatly improved short-term precision compared with the semi-automated version. To validate the automated FE tool, a clinical cohort consisting of 100 prior hip fracture cases and 300 matched controls was obtained from a local community clinical center. Both the automated FE tool and femoral bone mineral density (BMD) were applied to discriminate the fracture cases from the controls. Femoral BMD is the gold standard reference recommended by the World Health Organization for screening osteoporosis and for assessing hip fracture risk. The accuracy was measured by the area under ROC curve (AUC) and odds ratio (OR). Compared with femoral BMD (AUC = 0.71, OR = 2.07), the automated FE tool had a considerably improved accuracy (AUC = 0.78, OR = 2.61 at the trochanter). This work made a large step toward applying our DXA-based FE model as a routine clinical tool for the assessment of hip fracture risk. Furthermore, the automated computer program can be embedded into a web-site as an internet application. Copyright © 2017 Elsevier B.V. All rights reserved.

Preparation of Mo-Re-C samples containing Mo{sub 7}Re{sub 13}C with the β-Mn-type structure by solid state reaction of planetary-ball-milled powder mixtures of Mo, Re and C, and their crystal structures and superconductivity

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

Oh-ishi, Katsuyoshi, E-mail: oh-ishi@kc.chuo-u.ac.jp; Nagumo, Kenta; Tateishi, Kazuya

Mo-Re-C compounds containing Mo{sub 7}Re{sub 13}C with the β-Mn structure were synthesized with high-melting-temperature metals Mo, Re, and C powders using a conventional solid state method with a planetary ball milling machine instead of the arc melting method. Use of the ball milling machine was necessary to obtain Mo{sub 7}Re{sub 13}C with the β-Mn structure using the solid state method. Almost single-phase Mo{sub 7}Re{sub 13}C with a trace of impurity were obtained using the synthesis method. By XRF and lattice parameter measurements on the samples, Fe element existed in the compound synthesized using the planetary ball milling machine with amore » pot and balls made of steel, though Fe element was not detected in the compound synthesized using a pot and balls made of tungsten carbide. The former compound containg the Fe atom did not show superconductivity but the latter compound without the Fe atom showed superconductivity at 6.1 K. - Graphical abstract: Temperature dependence of the magnetic susceptibility measured under 10 Oe for the superconducting PBM-T samples without Fe element and non-superconducting PBM-S with Fe element. The inset is the enlarged view of the data for the PBM-S sample.« less

Sulfur, sulfides, oxides and organic matter aggregated in submarine hydrothermal plumes at 9°50‧N East Pacific Rise

NASA Astrophysics Data System (ADS)

Breier, J. A.; Toner, B. M.; Fakra, S. C.; Marcus, M. A.; White, S. N.; Thurnherr, A. M.; German, C. R.

2012-07-01

Deep-sea hydrothermal plume particles are known to sequester seawater trace elements and influence ocean-scale biogeochemical budgets. The relative importance of biotic versus abiotic oxidation-reduction and other particle-forming reaction, however, and the mechanisms of seawater trace element sequestration remain unknown. Suspended particulate material was collected from a non-buoyant hydrothermal plume by in situ filtration at 9°50‧N East Pacific Rise during a 3-day, 24 sample, time-series. Twenty-three samples were digested for total elemental analysis. One representative sample was selected for particle-by-particle geochemical analyses including elemental composition by X-ray fluorescence, speciation of Fe, S, and C by 1s X-ray absorption near edge structure spectroscopy, and X-ray diffraction. Consistent with past studies, positive linear correlations were observed for P, V, As, and Cr with Fe in the bulk chemistry. Arsenic was associated with both Fe oxyhydroxides and sulfides but not uniformly distributed among either mineral type. Particle aggregation was common. Aggregates were composed of minerals embedded in an organic matrix; the minerals ranged from <20 nm to >10 μm in diameter. The speciation of major mineral forming elements (Fe, Mn, S) was complex. Over 20 different minerals were observed, nine of which were either unpredicted by thermodynamic modeling or had no close match in the thermodynamic database. Sulfur-bearing phases consisted of polysulfides (S6, S8), and metal sulfides (Fe, Cu, Zn, Mn). Four dominant species, Fe oxyhydroxide, Fe monosulfide, pyrrhotite, and pyrite, accounted for >80% of the Fe present. Particulate Mn was prevalent in both oxidized and reduced minerals. The organic matrix was: (1) always associated with minerals, (2) composed of biomolecules, and (3) rich in S. Possible sources of this S-rich organic matter include entrained near vent biomass and in situ production by S-oxidizing microorganisms. These results indicate that particle aggregation with organic material is prevalent in dispersing hydrothermal plume fluxes, as well as in sinking particulate matter at this site. Particle aggregation and organic coatings can influence the reactivity, transport, and residence time of hydrothermal particles in the water column. Thus a biogeochemical approach is critical to understanding the net effect of hydrothermal fluxes on ocean and sedimentary trace element budgets.

Elemental concentration analysis in brain structures from young, adult and old Wistar rats by total reflection X-ray fluorescence with synchrotron radiation

NASA Astrophysics Data System (ADS)

Serpa, R. F. B.; de Jesus, E. F. O.; Anjos, M. J.; do Carmo, M. G. T.; Moreira, S.; Rocha, M. S.; Martinez, A. M. B.; Lopes, R. T.

2006-11-01

The knowledge of the spatial distribution and the local concentration of trace elements in tissues are of great importance since trace elements are involved in a number of metabolic and physiological processes in the human body, and their deficiency and excess may lead to different metabolic disorders. In this way, the main goal of this work is to compare the elemental concentration in different brain structures, namely temporal cortex, entorhinal cortex, visual cortex and hippocampus, from Wistar female rats ( n = 15) with different ages: 2, 8 and 48 weeks. The measurements were performed at the Synchrotron Light Brazilian Laboratory, Campinas, São Paulo, Brazil. In the entorhinal cortex, the following elements decreased with age: Zn, S, Cl, K, Ca and Br. In the temporal cortex, Ca, Fe and Br levels increased with aging and on the other hand, P, S, Cl, K and Rb levels decreased with aging. In the visual cortex almost all the elements decreased with aging: Cl, Ca, Fe, Ni and Zn. In the hippocampus, in turn, most of the elements identified, increased with aging: Al, P, S, K, Fe, Cu, Zn and Rb. The increase of Fe with aging in the hippocampus is an important fact that will be studied, since it is involved in oxidative stress. It is believed that oxidative stress is the one of the main causes responsible for neuronal death in Parkinson's disease.

Analysis of laser induced plasma of lithium iron phosphate/LiFePO4 using Nd:YAG laser at low pressure

NASA Astrophysics Data System (ADS)

Suliyanti, M. M.; Hidayah, A. N.; Isnaeni

2017-04-01

Preliminary analysis of lithium in Lithium Iron Phosphate (LiFePO4) powder using laser induced plasma spectroscopy at low pressure had been done. Recently, LiFePO4-based batteries are widely used in most electric cars and bikes due to less toxic. However, lithium (Li) element is very difficult to detect since it is a very light element. In this work, we used a Nd:YAG laser (1064 nm wavelength, 5 ns pulse width at 10 Hz repetition rate) that was focused on LiFePO4 sample at low pressure. The main Li peak emission in LiFePO4 powder and sheet can be easily detected using this technique. We report the results of experimental study on Li element emission lines at wavelength 460.18 nm, 610.37 nm and 670.83 nm using 2 mJ and 12 mJ laser irradiation at 5 Torr and 35 Torr air atmosphere. The results of this study showed promising application of laser-induced plasma spectroscopy to detect and analyse Li in various samples.

Ternary NiFeX as soft biasing film in a magnetoresistive sensor

NASA Astrophysics Data System (ADS)

Chen, Mao-Min; Gharsallah, Neila; Gorman, Grace L.; Latimer, Jacquie

1991-04-01

The properties of NiFeX ternary films (X being Al, Au, Nb, Pd, Pt, Si, and Zr) have been studied for soft-film biasing of the magnetoresistive (MR) trilayer sensor. In general, the addition of the element X into the NiFe alloy film decreases the saturation magnetization Bs and magnetoresistance coefficient of the film, while increasing the film's electrical resistivity ρ. One of the desirable properties of a soft film for biasing is high sheet resistance for minimum current flow. A figure of merit Bsρ that takes into account both the rate of increase in Bs and the rate of decrease in ρ when adding X element was derived to compare the effectiveness of various X elements in reducing the current shunting through the soft-film layer. Using this criterion, NiFeNb and NiFeZr emerge as good soft-film materials having a maximum sheet resistance relative to the MR layer. Other critical properties such as magnetoresistance coefficient, magnetostriction, coercivity, and anisotropy field were also examined and are discussed in this paper.

Effects of trace element addition on process stability during anaerobic co-digestion of OFMSW and slaughterhouse waste.

PubMed

Moestedt, J; Nordell, E; Shakeri Yekta, S; Lundgren, J; Martí, M; Sundberg, C; Ejlertsson, J; Svensson, B H; Björn, A

2016-01-01

This study used semi-continuous laboratory scale biogas reactors to simulate the effects of trace-element addition in different combinations, while degrading the organic fraction of municipal solid waste and slaughterhouse waste. The results show that the combined addition of Fe, Co and Ni was superior to the addition of only Fe, Fe and Co or Fe and Ni. However, the addition of only Fe resulted in a more stable process than the combined addition of Fe and Co, perhaps indicating a too efficient acidogenesis and/or homoacetogenesis in relation to a Ni-deprived methanogenic population. The results were observed in terms of higher biogas production (+9%), biogas production rates (+35%) and reduced VFA concentration for combined addition compared to only Fe and Ni. The higher stability was supported by observations of differences in viscosity, intraday VFA- and biogas kinetics as well as by the 16S rRNA gene and 16S rRNA of the methanogens. Copyright © 2015 Elsevier Ltd. All rights reserved.

Calibration under uncertainty for finite element models of masonry monuments

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

Atamturktur, Sezer,; Hemez, Francois,; Unal, Cetin

2010-02-01

Historical unreinforced masonry buildings often include features such as load bearing unreinforced masonry vaults and their supporting framework of piers, fill, buttresses, and walls. The masonry vaults of such buildings are among the most vulnerable structural components and certainly among the most challenging to analyze. The versatility of finite element (FE) analyses in incorporating various constitutive laws, as well as practically all geometric configurations, has resulted in the widespread use of the FE method for the analysis of complex unreinforced masonry structures over the last three decades. However, an FE model is only as accurate as its input parameters, andmore » there are two fundamental challenges while defining FE model input parameters: (1) material properties and (2) support conditions. The difficulties in defining these two aspects of the FE model arise from the lack of knowledge in the common engineering understanding of masonry behavior. As a result, engineers are unable to define these FE model input parameters with certainty, and, inevitably, uncertainties are introduced to the FE model.« less

Numerical Calculation of Neoclassical Distribution Functions and Current Profiles in Low Collisionality, Axisymmetric Plasmas

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

B.C. Lyons, S.C. Jardin, and J.J. Ramos

2012-06-28

A new code, the Neoclassical Ion-Electron Solver (NIES), has been written to solve for stationary, axisymmetric distribution functions (f ) in the conventional banana regime for both ions and elec trons using a set of drift-kinetic equations (DKEs) with linearized Fokker-Planck-Landau collision operators. Solvability conditions on the DKEs determine the relevant non-adiabatic pieces of f (called h ). We work in a 4D phase space in which Ψ defines a flux surface, θ is the poloidal angle, v is the total velocity referenced to the mean flow velocity, and λ is the dimensionless magnetic moment parameter. We expand h inmore » finite elements in both v and λ . The Rosenbluth potentials, φ and ψ, which define the integral part of the collision operator, are expanded in Legendre series in cos χ , where χ is the pitch angle, Fourier series in cos θ , and finite elements in v . At each ψ , we solve a block tridiagonal system for hi (independent of fe ), then solve another block tridiagonal system for he (dependent on fi ). We demonstrate that such a formulation can be accurately and efficiently solved. NIES is coupled to the MHD equilibrium code JSOLVER [J. DeLucia, et al., J. Comput. Phys. 37 , pp 183-204 (1980).] allowing us to work with realistic magnetic geometries. The bootstrap current is calculated as a simple moment of the distribution function. Results are benchmarked against the Sauter analytic formulas and can be used as a kinetic closure for an MHD code (e.g., M3D-C1 [S.C. Jardin, et al ., Computational Science & Discovery, 4 (2012).]).« less

An attempt to diagnose cancer by PIXE

NASA Astrophysics Data System (ADS)

Uda, M.; Maeda, K.; Sasa, Y.; Kusuyama, H.; Yokode, Y.

1987-03-01

PIXE is suitable especially for trace elemental analysis for atoms with high atomic numbers, which are contained in matrices composed mainly of light elements such as biological materials. An attempt has been made to distinguish elemental concentrations of cancer tissues from those of normal ones. Kidney, testis and urinary bladder cancer tissues were examined by PIXE. Key elements to diagnose these cancers were Ca, Ti, Cr, Fe and Zn. Enrichment of Fe and Ti, and deficiency of Zn could be seen in the kidney cancer. An opposite tendency was observed in the testicular cancer. Imbalance of these elemental concentrations in characteristic organs might give us a possibility for cancer diagnosis.

Influence of trace elements mixture on bacterial diversity and fermentation characteristics of liquid diet fermented with probiotics under air-tight condition.

PubMed

He, Yuyong; Chen, Zhiyu; Liu, Xiaolan; Wang, Chengwei; Lu, Wei

2014-01-01

Cu2+, Zn2+, Fe2+ and I- are often supplemented to the diet of suckling and early weaning piglets, but little information is available regarding the effects of different Cu2+, Zn2+, Fe2+ and I- mixtures on bacteria growth, diversity and fermentation characteristics of fermented liquid diet for piglets. Pyrosequencing was performed to investigate the effect of Cu2+, Zn2+, Fe2+ and I- mixtures on the diversity, growth and fermentation characteristics of bacteria in the liquid diet fermented with Bacillus subtilis and Enterococcus faecalis under air-tight condition. Results showed that the mixtures of Cu2+, Zn2+, Fe2+ and I- at different concentrations promoted Bacillus growth, increased bacterial diversity and lactic acid production and lowered pH to about 5. The importance of Cu2+, Zn2+, Fe2+ and I- is different for Bacillus growth with the order Zn2+> Fe2+>Cu2+> I- in a 21-d fermentation and Cu2+>I->Fe2+>Zn2+ in a 42-d fermentation. Cu2+, Zn2+, Fe2+ and I- is recommended at a level of 150, 60, 150 and 0.6 mg/kg respectively for the production of fermented liquid diet with Bacillus subtilis. The findings improve our understanding of the influence of trace elements on liquid diet fermentation with probiotics and support the proper use of trace elements in the production of fermented liquid diet for piglets.

The Effect of Alloying Elements on Thermal Conductivity and Casting Characteristic in High Pressure Die Casting of Aluminum Alloy

NASA Astrophysics Data System (ADS)

Kim, Cheol-Woo; Cho, Jae-Ik; Choi, Se-Weon; Kim, Young-Chan; Kang, Chang-Seog

Recently, demand of aluminum alloys for use in high thermal conductivity application is increases but the most aluminum die casting alloys exhibit very lower thermal properties because of their high concentrations of alloying elements. However, those alloying elements are essential to obtain sufficient fluidity and mechanical strength. Therefore, the purpose of this study is to analyze the effect of alloying elements in die casting alloys, Si, Cu, Mg, Fe and Mn, in thermal conductivity, die casting characteristics and mechanical properties and find out the appropriate amount of each alloying element for development of heat sink component. The results showed that Mn had the most deleterious effect in thermal conductivity and Si and Fe contents were important to improve strength and limit casting defects, such as hot tearing and die soldering. The alloy with 0.2 1.0wt%Cu, 0.3 0.6wt%Fe and 1.0 2.0wt%Si showed very good combination of high thermal conductivity and good casting characteristics.

Effect of Silicon on Activity Coefficients of Platinum in Liquid Fe-Si, With Application to Core Formation

NASA Technical Reports Server (NTRS)

Righter, K.; Pando, K.; Danielson, L. R.; Humayun, M.

2017-01-01

Earth's core contains approximately 10% of a light element that is likely a combination of S, C, Si, and O, with Si possibly being the most abundant light element. Si dissolved into Fe liquids can have a large effect on the magnitude of the activity coefficient of siderophile elements (SE) in Fe liquids, and thus the partitioning behavior of those elements between core and mantle. The effect of Si can be small such as for Ni and Co, or large such as for Mo, Ge, Sb, As. The effect of Si on many siderophile elements is unknown yet could be an important, and as yet unquantified, influence on the core-mantle partitioning of SE. Here we report new experiments designed to quantify the effect of Si on the partitioning of Pt (with Re and Ru in progress or planned) between metal and silicate melt. The results will be applied to Earth, for which we have excellent constraints on the mantle Pt concentrations.

A baseline study on the concentration of trace elements in the surface sediments off Southwest coast of Tamil Nadu, India.

PubMed

Godson, Prince S; Magesh, N S; Peter, T Simon; Chandrasekar, N; Krishnakumar, S; Vincent, Salom Gnana Thanga

2018-01-01

Forty two surface sediment samples were collected in order to document baseline elemental concentration along the Southwest coast of Tamil Nadu, India. The elements detected were Manganese (Mn), Zinc (Zn), Iron (Fe), Copper (Cu), Nickel (Ni) and Lead (Pb). The concentration of Fe and Mn was primarily controlled by the riverine input. The source of Pb and Zn is attributed to leaded petrol and anti-biofouling paints. The calculated index (EF, Igeo and CF) suggests that the sediments of the study area are significantly enriched with all elements except Pb. The contamination factor showed the order of Mn>Zn>Fe>Cu>Ni>Pb. The sediment pollution index (SPI) revealed that the sediments belonged to low polluted to dangerous category. The correlation matrix and dendrogram showed that the elemental distribution was chiefly controlled by riverine input as well as anthropogenic activity in the coast. Copyright © 2017 Elsevier Ltd. All rights reserved.

Atomistic Simulations of Grain Boundary Pinning in CuFe Alloys

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

Zepeda-Ruiz, L A; Gilmer, G H; Sadigh, B

2005-05-22

The authors apply a hybrid Monte Carlo-molecular dynamics code to the study of grain boundary motion upon annealing of pure Cu and Cu with low concentrations of Fe. The hybrid simulations account for segregation and precipitation of the low solubility Fe, together with curvature driven grain boundary motion. Grain boundaries in two different systems, a {Sigma}7+U-shaped half-loop grain and a nanocrystalline sample, were found to be pinned in the presence of Fe concentrations exceeding 3%.

Dissociation of a ferric maltol complex and its subsequent metabolism during absorption across the small intestine of the rat.

PubMed Central

Barrand, M. A.; Callingham, B. A.; Dobbin, P.; Hider, R. C.

1991-01-01

1. The fate and disposition of [59Fe]-ferric [3H]-maltol after intravenous administration were investigated in anaesthetized rats. Immediate dissociation of ferric iron from maltol took place in the circulation even with high doses of ferric maltol (containing 1 mg elemental iron). In plasma samples withdrawn within 1 min of injection and subjected to gel filtration, 59Fe eluted with the high molecular weight proteins whilst the tritium was associated with low molecular weight material. 2. The rates of elimination of 59Fe and of tritium from the plasma and their ultimate fate were very different. The half life for 59Fe in the plasma was around 70 min and 59Fe appeared mainly in the bone marrow and liver. There was an initial rapid exit of tritium from the plasma with a half life of around 12 min. This was followed either by a plateau or by a rise in tritium levels, involving entry of maltol metabolites into the circulation. These metabolites could be recovered in the urine. 3. Entry of 59Fe and of tritium into the blood plasma after intraduodenal administration of [59Fe]-ferric [3H]-maltol was also very different. At low doses of ferric maltol (containing 100 micrograms elemental iron), the tritium appeared in the plasma in highest amounts within seconds and then decreased whilst there was a slow rise in 59Fe levels. At higher doses of ferric maltol (containing 7 mg elemental iron), levels of 59Fe in the plasma were highest at 5 min and then fell whereas tritium levels rose steadily. Mucosal processing of 59Fe prevented further entry of iron at high dose into the circulation.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1364845

Iron Isotope Systematics

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

Dauphas, Nicolas; John, Seth G.; Rouxel, Olivier

Iron is a ubiquitous element with a rich (i.e., complex) chemical behavior. It possesses three oxidation states, metallic iron (Fe0), ferrous iron (Fe2+) and ferric iron (Fe3+). The distribution of these oxidation states is markedly stratified in the Earth.

Light, alpha, and Fe-peak element abundances in the galactic bulge

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

Johnson, Christian I.; Rich, R. Michael; Kobayashi, Chiaki

2014-10-01

We present radial velocities and chemical abundances of O, Na, Mg, Al, Si, Ca, Cr, Fe, Co, Ni, and Cu for a sample of 156 red giant branch stars in two Galactic bulge fields centered near (l, b) = (+5.25,–3.02) and (0,–12). The (+5.25,–3.02) field also includes observations of the bulge globular cluster NGC 6553. The results are based on high-resolution (R ∼ 20,000), high signal-to-noise ration (S/N ≳ 70) FLAMES-GIRAFFE spectra obtained through the European Southern Observatory archive. However, we only selected a subset of the original observations that included spectra with both high S/N and that did notmore » show strong TiO absorption bands. This work extends previous analyses of this data set beyond Fe and the α-elements Mg, Si, Ca, and Ti. While we find reasonable agreement with past work, the data presented here indicate that the bulge may exhibit a different chemical composition than the local thick disk, especially at [Fe/H] ≳ –0.5. In particular, the bulge [α/Fe] ratios may remain enhanced to a slightly higher [Fe/H] than the thick disk, and the Fe-peak elements Co, Ni, and Cu appear enhanced compared to the disk. There is also some evidence that the [Na/Fe] (but not [Al/Fe]) trends between the bulge and local disk may be different at low and high metallicity. We also find that the velocity dispersion decreases as a function of increasing [Fe/H] for both fields, and do not detect any significant cold, high-velocity populations. A comparison with chemical enrichment models indicates that a significant fraction of hypernovae may be required to explain the bulge abundance trends, and that initial mass functions that are steep, top-heavy (and do not include strong outflow), or truncated to avoid including contributions from stars >40 M {sub ☉} are ruled out, in particular because of disagreement with the Fe-peak abundance data. For most elements, the NGC 6553 stars exhibit abundance trends nearly identical to comparable metallicity bulge field stars. However, the star-to-star scatter and mean [Na/Fe] ratios appear higher in the cluster, perhaps indicating additional self-enrichment.« less

Geographical traceability of virgin olive oils from south-western Spain by their multi-elemental composition.

PubMed

Beltrán, María; Sánchez-Astudillo, María; Aparicio, Ramón; García-González, Diego L

2015-02-15

The geographical traceability of virgin olive oil can be controlled by chemical species that are linked to the production area. Trace elements are among these species. The hypothesis is that the transfer of elements from the soil to the oil is subjected to minor variations and therefore this chemical information can be used for geographical traceability. In order to confirm this hypothesis, the trace elements of virgin olive oils from south-western Spain were analysed, and the same elements were determined in the corresponding olive-pomaces and soils. The differences in the concentration were studied according to cultivars and locations. Results show some coincidences in the selection of elements in soils (W, Fe, Na), olive-pomace (W, Fe, Na, Mg, Mn, Ca, Ba, Li) and olive oils (W, Fe, Mg, Mn, Ca, Ba, Li, Bi), which supports their utility in traceability. In the case of olive oils, 93% of the samples were correctly classified in their geographical origins (96% for Beas, 77% for Gibraleón, 91% for Niebla, and 100% for Sanlúcar de Guadiana). Copyright © 2014 Elsevier Ltd. All rights reserved.

The Energy Spectra of Heavy Nuclei Measured by the ATIC Experiment

NASA Technical Reports Server (NTRS)

Panov, A. D.; Adams, J. H.; Ahn, H. S.; Bashindzhagyan, G. L.; Batkov, K. E.; Chang, J.; Christl, M.; Fazley, A. R.; Ganel, O.; Gunasingha, R. M.

2004-01-01

ATIC (Advanced Thin Ionization Calorimeter) is a balloon-borne experiment to measure the spectra and composition of primary cosmic rays in the region of total energy from 100 GeV to near 100 TeV for Z from 1 to 26. ATIC consists of a pixelated silicon matrix detector to measure charge plus a fully active BGO calorimeter, to measure energy, located below a carbon target interleaved with three layers of scintillator hodoscope. The ATIC instrument had a second (scientific) flight from McMurdo, Antarctica from 12/29/02 to 1/18/03, yielding 20 days of good data. The GEANT 3.21 Monte Carlo code with the QGSM event generator and the FLUKA code with the DPMJET-II event generator were used to convert energy deposition measurements to primary energy. We present the preliminary energy spectra for the abundant elements C, O, Ne, Mg, Si and Fe and compare them with the results of the first (test) flight of ATIC in 2000-01 and with results from the HEAO-3 and CRN experiments.

Evolution of trace elements in the planetary boundary layer in southern China: Effects of dust storms and aerosol-cloud interactions

NASA Astrophysics Data System (ADS)

Li, Tao; Wang, Yan; Zhou, Jie; Wang, Tao; Ding, Aijun; Nie, Wei; Xue, Likun; Wang, Xinfeng; Wang, Wenxing

2017-03-01

Aerosols and cloud water were analyzed at a mountaintop in the planetary boundary layer in southern China during March-May 2009, when two Asian dust storms occurred, to investigate the effects of aerosol-cloud interactions (ACIs) on chemical evolution of atmospheric trace elements. Fe, Al, and Zn predominated in both coarse and fine aerosols, followed by high concentrations of toxic Pb, As, and Cd. Most of these aerosol trace elements, which were affected by dust storms, exhibited various increases in concentrations but consistent decreases in solubility. Zn, Fe, Al, and Pb were the most abundant trace elements in cloud water. The trace element concentrations exhibited logarithmic inverse relationships with the cloud liquid water content and were found highly pH dependent with minimum concentrations at the threshold of pH 5.0. The calculation of Visual MINTEQ model showed that 80.7-96.3% of Fe(II), Zn(II), Pb(II), and Cu(II) existed in divalent free ions, while 71.7% of Fe(III) and 71.5% of Al(III) were complexed by oxalate and fluoride, respectively. ACIs could markedly change the speciation distributions of trace elements in cloud water by pH modification. The in-cloud scavenging of aerosol trace elements likely reached a peak after the first 2-3 h of cloud processing, with scavenging ratios between 0.12 for Cr and 0.57 for Pb. The increases of the trace element solubility (4-33%) were determined in both in-cloud aerosols and postcloud aerosols. These results indicated the significant importance of aerosol-cloud interactions to the evolution of trace elements during the first several cloud condensation/evaporation cycles.

Modeling and analysis of the spectrum of the globular cluster NGC 2419

NASA Astrophysics Data System (ADS)

Sharina, M. E.; Shimansky, V. V.; Davoust, E.

2013-06-01

The properties of the stellar population of the unusual object NGC 2419 are studied; this is the most distant high-mass globular cluster of the Galaxy's outer halo, and a spectrum taken with the 1.93-m telescope of the Haute Provence Observatory displays elemental abundance anomalies. Since traditional high-resolution spectroscopicmethods are applicable to bright stars only, spectroscopic information for the cluster's stellar population as a whole, integrated along the spectrograph slit placed in various positions, is used. Population synthesis is carried out for the spectrum of NGC 2419 using synthetic spectra calculated from a grid of stellar model atmospheres, based on the theoretical isochrone from the literature that best fits the color-magnitude diagram of the cluster. The derived age (12.6 billion years), metallicity ([Fe/H] = -2.25 dex), and abundances of helium ( Y = 0.26) and other chemical elements (a total of 14) are in a good qualitative agreement with estimates from the literature made from high-resolution spectra of eight red giants in the cluster. The influence on the spectrum of deviations from local thermodynamic equilibrium is considered for several elements. The derived abundance of α-elements ([ α/Fe] = 0.13 dex, as the mean of [O/Fe], [Mg/Fe], and [Ca/Fe]) differs from the mean value in the literature ([ α/Fe] = 0.4 for the eight brightest red giants) and may be explained by recently discovered in NGC2419 large [a/Fe] dispersion. Further studies of the integrated properties of the stellar population in NGC 2419 using higher-resolution spectrographs in various wavelength ranges should help improve our understanding of the cluster's chemical anomalies.

[Determination of Mineral Elements in Choerospondias Axillaris and Its Extractives by ICP-AES].

PubMed

Zhai, Yu-xin; Chen, Jun; Li, Ti; Liu, Ji-yan; Wang, Xie-yi; Cheng, Chao; Liu, Cheng-mei

2015-04-01

Nine elements in Choerospondias axillaris flesh, peels, aqueous extractives and gastric digesta were determined by the inductively coupled plasma atomic emission spectrometry (ICP-AES) in the present study. The results showed that the contents of Fe, Ca, Zn, Mn, Al, Mg, Cu, K and P in the flesh were 27.37, 269.88, 1.51, 2.45, 1.95, 195.30, 2.45, 2,970.11, and 133.94 µg · g(-1), respectively. They are lower than that in the peels, about 40.31%, 11.70%, 21.68%, 4.27%, 10.58%, 15.76%, 68.72%, 42.04%, and 22.59%, respectively. For microwave assistant extraction, the release rate of Mn was highest (81.68%), while Fe was lowest (4.42%) in the flesh. The release rate of Zn was the highest (79.00%), while that of A1 was the lowest (4.94%) in the peels. Except Fe, Cu and Zn, the release rates of the other elements in flesh were higher than those in the peels. After gastric digestion, the release rates of nine elements were 3.25%-87.51% in the flesh and 7.11%-50.69% in the peels. The release rates of minerals in the flesh were found to be higher than those in the peels except Fe and Cu. Microwave assistant extraction can more efficiently release Fe, Ca, Mn, Mg and K from the flesh than the gastric digestion do. While gastric digestion had a significant effect on the peels, the release rates of elements, except Zn, were higher than those in microwave assistant extraction. Therefore, the difference of distribution and release of mineral elements between peels and flesh of Choerospondias axillaris was understood, which will provide a positive guide for further study of bioavailability of minerals for human body.

Finite element strategies to satisfy clinical and engineering requirements in the field of percutaneous valves.

PubMed

Capelli, Claudio; Biglino, Giovanni; Petrini, Lorenza; Migliavacca, Francesco; Cosentino, Daria; Bonhoeffer, Philipp; Taylor, Andrew M; Schievano, Silvia

2012-12-01

Finite element (FE) modelling can be a very resourceful tool in the field of cardiovascular devices. To ensure result reliability, FE models must be validated experimentally against physical data. Their clinical application (e.g., patients' suitability, morphological evaluation) also requires fast simulation process and access to results, while engineering applications need highly accurate results. This study shows how FE models with different mesh discretisations can suit clinical and engineering requirements for studying a novel device designed for percutaneous valve implantation. Following sensitivity analysis and experimental characterisation of the materials, the stent-graft was first studied in a simplified geometry (i.e., compliant cylinder) and validated against in vitro data, and then in a patient-specific implantation site (i.e., distensible right ventricular outflow tract). Different meshing strategies using solid, beam and shell elements were tested. Results showed excellent agreement between computational and experimental data in the simplified implantation site. Beam elements were found to be convenient for clinical applications, providing reliable results in less than one hour in a patient-specific anatomical model. Solid elements remain the FE choice for engineering applications, albeit more computationally expensive (>100 times). This work also showed how information on device mechanical behaviour differs when acquired in a simplified model as opposed to a patient-specific model.

The excretion of biotrace elements using the multitracer technique in tumour-bearing mice.

PubMed

Wang, X; Tian, J; Yin, X M; Zhang, X; Wang, Q Z

2000-12-01

A radioactive multitracer solution obtained from the nuclear reaction of selenium with 25 MeV/nucleon 40Ar ions was used for investigation of trace element excretion into the faeces and urine of cancerous mice. The excretion rates of 22 elements (Na, K, Rb, Mg, Ca, Sr, Ga, As, Sc, V, Cr, Mn, Co, Fe, Y, Zr, Mo, Nb, Tc, Ru, Ag and In) were simultaneously measured under strictly identical experimental conditions, in order to clarify the excretion behavior of these elements in cancerous mice. The faecal and urinary excretion rates of Mg, Sr, Ga, As, Sc, V, Cr, Mn, Co, Fe, Y, Zr, Nb, Ru and Mo in cancerous mice, showed the in highest value at 0-8 hours. The accumulative excretion of Ca, Mo, Y and Zr was decreased and Na, Fe, Mn and Co increased in tumour-bearing mice, when compared to normal mice.

Finite element modeling of mitral leaflet tissue using a layered shell approximation

PubMed Central

Ratcliffe, Mark B.; Guccione, Julius M.

2012-01-01

The current study presents a finite element model of mitral leaflet tissue, which incorporates the anisotropic material response and approximates the layered structure. First, continuum mechanics and the theory of layered composites are used to develop an analytical representation of membrane stress in the leaflet material. This is done with an existing anisotropic constitutive law from literature. Then, the concept is implemented in a finite element (FE) model by overlapping and merging two layers of transversely isotropic membrane elements in LS-DYNA, which homogenizes the response. The FE model is then used to simulate various biaxial extension tests and out-of-plane pressure loading. Both the analytical and FE model show good agreement with experimental biaxial extension data, and show good mutual agreement. This confirms that the layered composite approximation presented in the current study is able to capture the exponential stiffening seen in both the circumferential and radial directions of mitral leaflets. PMID:22971896

Deformation of Ordinary Chondrite Under Very Reducing Conditons: Implications for Liquid Metal Compositions, HSE Partitioning and Enstatite Chondrites

NASA Astrophysics Data System (ADS)

Rushmer, T.; Corgne, A.

2008-12-01

One important method in which to gain insight into metallic liquid compositions and their ability to control HSE (highly siderophile element) distribution is through experimentation. Deformation experiments can additionally provide information into mechanisms and chemical consequences of dynamic liquid metal segregation under a variety of conditions. We report results on metallic liquid HSE compositions and their distribution from a set of deformation experiments on a natural H6 ordinary chondrite, performed under very reducing conditions and a series of phase equilibria experiments focused on HSE partitioning between Si-rich and S-rich Fe molten alloys. The deformation experiments were conducted at temperatures between 925°C and 950°C, at 1.3 GPa confining pressure with a strain rate of 10-4/s. Major element analyses of both silicate and metal phases show that they are considerably reduced and the typically lithophile elements are behaving like siderophiles. Fe-Ni-Si compositions are found in the shear zones produced during the deformation experiment. Metallic compositions also include (Mg,Fe,Ca)S, Fe-Ni-Si, FeP, and Fe-Ni-S quench metal. Silicate phases include forsterite (Fo92-96) and enstatite (En98). Highly siderophile element (HSE) concentrations have been measured in the sulphide ((Fe,Mg,Ca)S) and metal (Fe- Ni-Si) phases by LA-ICPMS and compared with results from an earlier set of experiments on the same material but which were not performed under reducing conditions. The partitioning of the PGE is modified by the changing conditions with elements such as Ir and Os having higher DMetal/Sulphide values under reducing conditions. Partitioning experiments between molten FeS and Ni-, Si-bearing molten Fe were performed at 1.5-5.0 GPa and 1500-1750° to further investigate this observation. The starting material is synthetic, doped with a range of trace and HSE elements. The results confirm the preference of the HSE for the metallic phase with DMetal/Sulphide > 100 in most cases, in contrast to Cu and Ag, which have D values near or below 1, respectively. Our results also suggest the possibility of significant PGE fractionation since D values are larger for Ir and Os and smaller for Pd and Au, with Pt, Ru, Rh having intermediate values. It is not clear with the present data set whether T and P variations can affect significantly HSE partitioning. These results have been applied to the most naturally reduced material we know, the Enstatite chondrites. Several E chondrites have bulk HSE data available, but no HSE data available on sulphide and metallic phases themselves. We have now a set of HSE data for individual metallic phases in several enstatite chondrites, both EH and ELs. The bulk data show that for elements such as Os and Pd, the abundances are positively correlated and overall Pd is much higher in abundance. We find in the experiments that DPd ranges between 10-100, but do not fully explain the bulk trends. Additional phases, such as FeP have therefore been analyzed and we find that Pd is concentrated in FeP and the presence of schreibersite may help explain the high Pd ratios (e.g. Pd/Ir) observed in the Enstatite chondrites.

Fuel Performance Calculations for FeCrAl Cladding in BWRs

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

George, Nathan; Sweet, Ryan; Maldonado, G. Ivan

2015-01-01

This study expands upon previous neutronics analyses of the reactivity impact of alternate cladding concepts in boiling water reactor (BWR) cores and directs focus toward contrasting fuel performance characteristics of FeCrAl cladding against those of traditional Zircaloy. Using neutronics results from a modern version of the 3D nodal simulator NESTLE, linear power histories were generated and supplied to the BISON-CASL code for fuel performance evaluations. BISON-CASL (formerly Peregrine) expands on material libraries implemented in the BISON fuel performance code and the MOOSE framework by providing proprietary material data. By creating material libraries for Zircaloy and FeCrAl cladding, the thermomechanical behaviormore » of the fuel rod (e.g., strains, centerline fuel temperature, and time to gap closure) were investigated and contrasted.« less

Mapping Metal Elements of Shuangbai Dinosaur Fossil by Synchrotron X-ray Fluorescence Microprobe

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

Wang, Y.; Qun, Y; Ablett, J

The metal elements mapping of Shuangbai dinosaur fossil, was obtained by synchrotron x-ray fluorescence (SXRF). Eight elements, Ca, Mn, Fe, Cu, Zn, As, Y and Sr were determined. Elements As and Y were detected for the first time in the dinosaur fossil. The data indicated that metal elements are asymmetrical on fossil section. This is different from common minerals. Mapping metals showed that metal element As is few. The dinosaur most likely belongs to natural death. This is different from Zigong dinosaurs which were found dead from poisoning. This method has been used to find that metals Fe and Mnmore » are accrete, and the same is true for Sr and Y. This study indicated that colloid granule Fe and Mn, as well as Sr and Y had opposite electric charges in lithification process of fossils. By this analysis, compound forms can be ascertained. Synchrotron light source x-ray fluorescence is a complementary method that shows mapping of metal elements at the dinosaur fossil, and is rapid, exact and intuitionist. This study shows that dinosaur fossil mineral imaging has a potential in reconstructing the paleoenvironment and ancient geology.« less

The Abundances of the Fe Group Elements in AV 304, an Abundance Standard in the Small Magellanic Cloud

NASA Astrophysics Data System (ADS)

Peters, Geraldine J.; Lanz, Thierry; Bouret, Jean-Claude; Proffitt, Charles R.; Adelman, Saul J.; Hubeny, Ivan

2018-06-01

AV 304 is a B0.5 IV field star in the Small Magellanic Cloud with ultra-sharp spectral lines that has emerged as an abundance standard. We have combined recent spectroscopic observations from the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope with archival data from the Far Ultraviolet Spectroscopic Explorer (FUSE) and ESO’s VLT/UVES to determine the abundances of the Fe group elements (Ti, V, Cr, Mn, Fe, Co, & Ni). The analysis was carried through using the Hubeny/Lanz NLTE programs TLUSTY/SYNSPEC. The COS observations were secured with the G130M, G160M, G185M, and G225M gratings. Combined with the FUSE data, we have achieved spectral coverage in the UV from 950 to 2400 A. Measurable lines from the Fe group, except for a very few multiplets of Fe II, III are not observed in optical spectra. The following stellar parameters were found: Teff = 27500±500 K, log g = 3.7±0.1 cm/s2, Vturb= 1±1 km/s, and v sin i = 8 ±2 km/s. The Fe abundance appears to be only slightly lower than the mean depletion in the SMC, but the other Fe group elements are underabundant by 0.3 dex or more. This study confirmed the low abundance of nitrogen (-1.25 dex relative to the solar value) that was reported by Peters & Adelman (ASP Conf. Series, 348, p. 136, 2006). Whereas the light elements are delivered to the ISM by core-collapse supernovae (CCSNe), the Fe group elements are believed to come mostly from low/intermediate mass binaries containing white dwarfs that undergo SNe Ia explosions. A single SNe Ia can deliver 0.5 solar masses of pure Fe (and maybe Mn) to the ISM compared with about 0.07 solar masses from a CCSNe. It appears that there is very little processed material from its interior in the atmosphere of AV 304 and that the star did not form from an interstellar cloud that was enriched by material from earlier supernova activity. Support from STScI grants HST-GO-14081.002 and HST-GO-13346.022, and USC’s Women in Science and Engineering (WiSE) program is greatly appreciated.

In situ determination of binary alloy melt compositions in the LHDAC by X- Radiography

NASA Astrophysics Data System (ADS)

Lord, O. T.; Walter, M. J.; Walker, D.; Clark, S. M.

2008-12-01

Constraining the light element in Earth's molten outer core requires an understanding of the melting phase relations in iron-light element binary systems. For example, it is critical to determine the composition of liquids at binary eutectics. Typically such measurements are carried out after the sample has been quenched in temperature and pressure. Such 'cook and look' methods possibly suffer from systematic errors introduced by exsolution of the light element from the melt on quench and error in the reintegration of the liquid composition [1]. Here, we present a novel method for the determination of melt compositions in iron-light element binary systems in situ in the LHDAC at simultaneous high-pressure, high-temperature conditions. Samples consist of a light element bearing compound, such as FeO, surrounded by a pure iron ring, forming a donut ~100 μm in diameter and ~15 μm thick. The donuts are loaded into stainless steel gaskets in the DAC, sandwiched between discs fabricated from sol-gel deposited nanocrystalline Al2O3 with similar dimensions to the donut. Pressure is monitored by ruby fluorescence during compression. The sample is heated at the boundary between the iron and light element compound using two 100 W IR lasers in a double-sided configuration at beamline 12.2.2 at the Advanced Light Source. Temperature is measured by spectroradiometry. Before, during and after melting, X-radiographic images of the sample are taken by shining a defocused beam of synchrotron X-rays through the sample and onto a CdWO4 phosphor. The visible light from the phosphor is then focused onto a high resolution CCD, where absorption contrast images are recorded. The absorption of the molten region is then determined, and it's composition calculated by linear interpolation between the absorption of the two solid end members. As a test of the reliability of the method we measured the Fe-FeS eutectic to 20 GPa and our results are in good agreement with previous studies that are based on various ex situ techniques. We measured the eutectic composition between Fe and Fe3C up to 44 GPa, and found that the carbon content of the eutectic drops rapidly above about 10 GPa, dropping to less that 1 wt% by 44 GPa. This result is generally consistent with the thermodynamic calculations of Wood [2]. Experiments on the Fe-FeSi eutectic yielded an increase in the Si content of the eutectic to 35 GPa, consistent with data from large volume press experiments [3] Notably, melting experiments at 35-43 GPa and ~2500 K on a boundary between Fe and FeO failed to yield evidence of a melt with a composition distinguishable from pure iron. However, an experiment at 12 GPa and 2700 K between Fe and FeO(OH) did yield a melt with a composition intermediate between the two end members. This suggests that O solubility in the Fe-O eutectic melt is low at mid-mantle pressures, but that H may dissolve into the melt by itself or in combination with O. [1] Walker, D., 2005. Core-Mantle chemical issues. Canad. Min., 43, 1553-1564 [2] Wood, B. J., 1993. Carbon in the core. Earth Planet Sci. Lett., 117, 593-607 [3] Kuwayama, Y. & Hirose, K., 2004. Phase relations in the system Fe-FeSi at 21 GPa. Am. Min., 89, 273-276.

NOTE: Do acupuncture points exist?

NASA Astrophysics Data System (ADS)

Yan, Xiaohui; Zhang, Xinyi; Liu, Chenglin; Dang, Ruishan; Huang, Yuying; He, Wei; Ding, Guanghong

2009-05-01

We used synchrotron x-ray fluorescence analysis to probe the distribution of four chemical elements in and around acupuncture points, two located in the forearm and two in the lower leg. Three of the four acupuncture points showed significantly elevated concentrations of elements Ca, Fe, Cu and Zn in relation to levels in the surrounding tissue, with similar elevation ratios for Cu and Fe. The mapped distribution of these elements implies that each acupuncture point seems to be elliptical with the long axis along the meridian.

Master standard data quantity food production code. Macro elements for synthesizing production labor time.

PubMed

Matthews, M E; Waldvogel, C F; Mahaffey, M J; Zemel, P C

1978-06-01

Preparation procedures of standardized quantity formulas were analyzed for similarities and differences in production activities, and three entrée classifications were developed, based on these activities. Two formulas from each classification were selected, preparation procedures were divided into elements of production, and the MSD Quantity Food Production Code was applied. Macro elements not included in the existing Code were simulated, coded, assigned associated Time Measurement Units, and added to the MSD Quantity Food Production Code. Repeated occurrence of similar elements within production methods indicated that macro elements could be synthesized for use within one or more entrée classifications. Basic elements were grouped, simulated, and macro elements were derived. Macro elements were applied in the simulated production of 100 portions of each entrée formula. Total production time for each formula and average production time for each entrée classification were calculated. Application of macro elements indicated that this method of predetermining production time was feasible and could be adapted by quantity foodservice managers as a decision technique used to evaluate menu mix, production personnel schedules, and allocation of equipment usage. These macro elements could serve as a basis for further development and refinement of other macro elements which could be applied to a variety of menu item formulas.

3D FEM Geometry and Material Flow Optimization of Porthole-Die Extrusion

NASA Astrophysics Data System (ADS)

Ceretti, Elisabetta; Mazzoni, Luca; Giardini, Claudio

2007-05-01

The aim of this work is to design and to improve the geometry of a porthole-die for the production of aluminum components by means of 3D FEM simulations. In fact, the use of finite element models will allow to investigate the effects of the die geometry (webs, extrusion cavity) on the material flow and on the stresses acting on the die so to reduce the die wear and to improve the tool life. The software used to perform the simulations was a commercial FEM code, Deform 3D. The technological data introduced in the FE model have been furnished by METRA S.p.A. Company, partner in this research. The results obtained have been considered valid and helpful by the Company for building a new optimized extrusion porthole-die.

Numerical assessment of residual formability in sheet metal products: towards design for sustainability

NASA Astrophysics Data System (ADS)

Falsafi, Javad; Demirci, Emrah; Silberschmidt, Vadim. V.

2016-08-01

A new computational scheme is presented to addresses cold recyclability of sheet- metal products. Cold recycling or re-manufacturing is an emerging area studied mostly empirically; in its current form, it lacks theoretical foundation especially in the area of sheet metals. In this study, a re-formability index was introduced based on post-manufacture residual formability in sheet metal products. This index accounts for possible levels of deformation along different strain paths based on Polar Effective Plastic Strain (PEPS) technique. PEPS is strain-path independent, hence provides a foundation for residual formability analysis. A user- friendly code was developed to implement this assessment in conjunction with advanced finite- element (FE) analysis. The significance of this approach is the advancement towards recycling of sheet metal products without melting them.

Modelling of Microstructure Changes in Hot Deformed Materials Using Cellular Automata

NASA Astrophysics Data System (ADS)

Kuc, Dariusz; Gawąd, Jerzy

2011-01-01

The paper is focused on application of multi-scale 2D method. Model approach consists of Cellular Automata (CA) model of microstructure development and the finite element code to solve thermo-mechanical problem. Dynamic recrystallization phenomenon is taken into account in 2D CA model which takes advantage of explicit representation of microstructure, including individual grains and grain boundaries. Flow stress is the main material parameter in mechanical part of FE and is calculated on the basis of average dislocation density obtained from CA model. The results attained from the model were validated with the experimental data. In the present study, austenitic steel X3CrNi18-10 was investigated. The examination of microstructure for the initial and final microstructures was carried out, using light microscopy and transmission electron microscopy.

Stochastic filtering for damage identification through nonlinear structural finite element model updating

NASA Astrophysics Data System (ADS)

Astroza, Rodrigo; Ebrahimian, Hamed; Conte, Joel P.

2015-03-01

This paper describes a novel framework that combines advanced mechanics-based nonlinear (hysteretic) finite element (FE) models and stochastic filtering techniques to estimate unknown time-invariant parameters of nonlinear inelastic material models used in the FE model. Using input-output data recorded during earthquake events, the proposed framework updates the nonlinear FE model of the structure. The updated FE model can be directly used for damage identification and further used for damage prognosis. To update the unknown time-invariant parameters of the FE model, two alternative stochastic filtering methods are used: the extended Kalman filter (EKF) and the unscented Kalman filter (UKF). A three-dimensional, 5-story, 2-by-1 bay reinforced concrete (RC) frame is used to verify the proposed framework. The RC frame is modeled using fiber-section displacement-based beam-column elements with distributed plasticity and is subjected to the ground motion recorded at the Sylmar station during the 1994 Northridge earthquake. The results indicate that the proposed framework accurately estimate the unknown material parameters of the nonlinear FE model. The UKF outperforms the EKF when the relative root-mean-square error of the recorded responses are compared. In addition, the results suggest that the convergence of the estimate of modeling parameters is smoother and faster when the UKF is utilized.

Development, Validation and Parametric study of a 3-Year-Old Child Head Finite Element Model

NASA Astrophysics Data System (ADS)

Cui, Shihai; Chen, Yue; Li, Haiyan; Ruan, ShiJie

2015-12-01

Traumatic brain injury caused by drop and traffic accidents is an important reason for children's death and disability. Recently, the computer finite element (FE) head model has been developed to investigate brain injury mechanism and biomechanical responses. Based on CT data of a healthy 3-year-old child head, the FE head model with detailed anatomical structure was developed. The deep brain structures such as white matter, gray matter, cerebral ventricle, hippocampus, were firstly created in this FE model. The FE model was validated by comparing the simulation results with that of cadaver experiments based on reconstructing the child and adult cadaver experiments. In addition, the effects of skull stiffness on the child head dynamic responses were further investigated. All the simulation results confirmed the good biofidelity of the FE model.

Ab-initio Calculation of the XANES of Lithium Phosphates and LiFePO4

NASA Astrophysics Data System (ADS)

Yiu, Y. M.; Yang, Songlan; Wang, Dongniu; Sun, Xueliang; Sham, T. K.

2013-04-01

Lithium iron phosphate has been regarded as a promising cathode material for the next generation lithium ion batteries due to its high specific capacity, superior thermal and cyclic stability [1]. In this study, the XANES (X-ray Absorption Near Edge Structure) spectra of lithium iron phosphate and lithium phosphates of various compositions at the Li K, P L3,2, Fe M3,2 and O K-edges have been simulated self-consistently using ab-initio calculations based on multiple scattering theory (the FEFF9 code) and DFT (Density Functional Theory, the Wien2k code). The lithium phosphates under investigation include LiFePO4, γ-Li3PO4, Li4P2O7 and LiPO3. The calculated spectra are compared to the experimental XANES recorded in total electron yield (TEY) and fluorescence yield (FLY). This work was carried out to assess the XANES of possible phases presented in LiFePO4 based Li ion battery applications [2].

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

Roederer, Ian U.; Karakas, Amanda I.; Pignatari, Marco

We present a detailed analysis of the composition and nucleosynthetic origins of the heavy elements in the metal-poor ([Fe/H] = −1.62 ± 0.09) star HD 94028. Previous studies revealed that this star is mildly enhanced in elements produced by the slow neutron-capture process (s process; e.g., [Pb/Fe] = +0.79 ± 0.32) and rapid neutron-capture process (r process; e.g., [Eu/Fe] = +0.22 ± 0.12), including unusually large molybdenum ([Mo/Fe] = +0.97 ± 0.16) and ruthenium ([Ru/Fe] = +0.69 ± 0.17) enhancements. However, this star is not enhanced in carbon ([C/Fe] = −0.06 ± 0.19). We analyze an archival near-ultraviolet spectrum of HD 94028, collected using the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope, and other archival optical spectra collected frommore » ground-based telescopes. We report abundances or upper limits derived from 64 species of 56 elements. We compare these observations with s-process yields from low-metallicity AGB evolution and nucleosynthesis models. No combination of s- and r-process patterns can adequately reproduce the observed abundances, including the super-solar [As/Ge] ratio (+0.99 ± 0.23) and the enhanced [Mo/Fe] and [Ru/Fe] ratios. We can fit these features when including an additional contribution from the intermediate neutron-capture process (i process), which perhaps operated through the ingestion of H in He-burning convective regions in massive stars, super-AGB stars, or low-mass AGB stars. Currently, only the i process appears capable of consistently producing the super-solar [As/Ge] ratios and ratios among neighboring heavy elements found in HD 94028. Other metal-poor stars also show enhanced [As/Ge] ratios, hinting that operation of the i process may have been common in the early Galaxy.« less

Trace element supplementation in the biogas production from wheat stillage--optimization of metal dosing.

PubMed

Schmidt, Thomas; Nelles, Michael; Scholwin, Frank; Pröter, Jürgen

2014-09-01

A trace element dosing strategy for the anaerobic digestion of wheat stillage was developed in this study. Mesophilic CSTR reactors were operated with the sulfuric substrate wheat stillage in some cases under trace element deficiency. After supplementing trace elements during the start-up, one of the elements of Fe, Ni, Co, Mo, and W were depleted in one digester while still augmenting the other elements to determine minimum requirements for each element. The depletion of Fe and Ni resulted in a rapid accumulation of volatile fatty acids while Co and W seem to have a long-term effect. Based on the results it was possible to reduce the dosing of trace elements, which is positive with reference to economic and environmental aspects. Copyright © 2014 Elsevier Ltd. All rights reserved.

Interactive Finite Elements for General Engine Dynamics Analysis

NASA Technical Reports Server (NTRS)

Adams, M. L.; Padovan, J.; Fertis, D. G.

1984-01-01

General nonlinear finite element codes were adapted for the purpose of analyzing the dynamics of gas turbine engines. In particular, this adaptation required the development of a squeeze-film damper element software package and its implantation into a representative current generation code. The ADINA code was selected because of prior use of it and familiarity with its internal structure and logic. This objective was met and the results indicate that such use of general purpose codes is viable alternative to specialized codes for general dynamics analysis of engines.

Concentrations of macro- and micro-elements in the milk of pasture-fed thoroughbred mares.

PubMed

Grace, N D; Pearce, S G; Firth, E C; Fennessy, P F

1999-03-01

To determine the changes in Ca, P, Mg, Na, K, S, Cu, Fe and Zn concentrations of milk during the lactation in pasture-fed Thoroughbred mares and then calculate the dietary mineral requirements of the sucking foal and the lactating mare. Milk was sampled on days 1, 3, 7, 14, 21, 28 and at various times between 55 to 65, 85 to 95 and 135 to 150 days after parturition from 21 pasture-fed mares. The concentrations of macro- and micro-elements in the milk were determined by inductively coupled plasma emission spectrometry. Concentrations (mg/L) of these elements were highest in colostrum (Mg 302, Na 561, K 955, S 1035, Cu 0.76, Fe 0.79 and Zn 5.5) except for Ca (1245) and P (895), which where highest on day 7. The mean milk mineral element concentrations (mg/L) over days 55 to 150 were Ca 843, P 543, Mg 47, Na 120, K 590, S 219, Cu 0.19, Fe 0.34 and Zn 2.1. The mean plasma element concentrations (mg/L) over the same period were Ca 120, P 77.1, Mg 17.0, Na 3110, K 168, S 983, Cu 1.1, Fe 1.5 and Zn 0.49. Concentration gradients between plasma and milk were observed and, in the case of Ca, P, Mg, K and Zn, their concentrations in milk were greater than those in plasma, while a reverse situation was observed for Na, S, Cu and Fe. With the exception of Ca and P, the highest concentrations of mineral elements were observed in the colostrum. The nursing foal should have access to good pasture or creep feed, because the intakes of Ca, P and Cu from milk may be less than optimum to meet the daily mineral element requirements.

Examining Two Sets of Introgression Lines in Rice (Oryza sativa L.) Reveals Favorable Alleles that Improve Grain Zn and Fe Concentrations

PubMed Central

Hu, Xia; Cheng, Li-Rui; Xu, Jian-Long; Shi, Yu-Min; Li, Zhi-Kang

2015-01-01

In the modern world, the grain mineral concentration (GMC) in rice (Oryza sativa L.) not only includes important micronutrient elements such as iron (Fe) and zinc (Zn), but it also includes toxic heavy metal elements, especially cadmium (Cd) and lead (Pb). To date, the genetic mechanisms underlying the regulation of GMC, especially the genetic background and G × E effects of GMC, remain largely unknown. In this study, we adopted two sets of backcross introgression lines (BILs) derived from IR75862 (a Zn-dense rice variety) as the donor parent and two elite indica varieties, Ce258 and Zhongguangxiang1, as recurrent parents to detect QTL affecting GMC traits including Fe, Zn, Cd and Pb concentrations in two environments. We detected a total of 22 loci responsible for GMC traits, which are distributed on all 12 rice chromosomes except 5, 9 and 10. Six genetic overlap (GO) regions affecting multiple elements were found, in which most donor alleles had synergistic effects on GMC. Some toxic heavy metal-independent loci (such as qFe1, qFe2 and qZn12) and some regions that have opposite genetic effects on micronutrient (Fe and Zn) and heavy metal element (Pb) concentrations (such as GO-IV) may be useful for marker-assisted biofortification breeding in rice. We discuss three important points affecting biofortification breeding efforts in rice, including correlations between different GMC traits, the genetic background effect and the G × E effect. PMID:26161553

Structural classification of RAO3( MO) n compounds ( R =Sc, In, Y, or lanthanides; A =Fe(III), Ga, Cr, or Al; M =divalent cation; n = 1-11)

NASA Astrophysics Data System (ADS)

Kimizuka, Noboru; Mohri, Takahiko

1989-01-01

A series of new compounds RAO3( MO) n ( n = 1-11) having spinel, YbFe 2O 4, or InFeO 3(ZnO) n types of structures were newly synthesized ( R =Sc, In, Y, Lu, Yb, Tm, or Er; A =Fe(III), Ga, Cr, or Al; M =Mg, Mn, Fe(II), Co, Ni, Zn, or Cd) at elevated temperatures. The conditions of synthesis and the lattice constants for these compounds are reported. The stacking sequences of the InO 1.5, (FeZn)O 2.5, and ZnO layers for InFeO 3(ZnO) 10 and the TmO 1.5, (AlZn)O 2.5, and ZnO layers for TmAlO 3(ZnO) 11 are presented, respectively. The crystal structures of the( RAO3) m( MO) n phases ( R =Sc, In, Y, or lanthanide elements; A =Fe(III), Ga, Cr, or Al; M =divalent cation elements; m and n =integer) are classified into four crystal structure types (K 2NiF 4, CaFe 2O 4, YbFe 2O 4, and spinel), based upon the constituent cations R, A, and M

Quasi-static earthquake cycle simulation based on nonlinear viscoelastic finite element analyses

NASA Astrophysics Data System (ADS)

Agata, R.; Ichimura, T.; Hyodo, M.; Barbot, S.; Hori, T.

2017-12-01

To explain earthquake generation processes, simulation methods of earthquake cycles have been studied. For such simulations, the combination of the rate- and state-dependent friction law at the fault plane and the boundary integral method based on Green's function in an elastic half space is widely used (e.g. Hori 2009; Barbot et al. 2012). In this approach, stress change around the fault plane due to crustal deformation can be computed analytically, while the effects of complex physics such as mantle rheology and gravity are generally not taken into account. To consider such effects, we seek to develop an earthquake cycle simulation combining crustal deformation computation based on the finite element (FE) method with the rate- and state-dependent friction law. Since the drawback of this approach is the computational cost associated with obtaining numerical solutions, we adopt a recently developed fast and scalable FE solver (Ichimura et al. 2016), which assumes use of supercomputers, to solve the problem in a realistic time. As in the previous approach, we solve the governing equations consisting of the rate- and state-dependent friction law. In solving the equations, we compute stress changes along the fault plane due to crustal deformation using FE simulation, instead of computing them by superimposing slip response function as in the previous approach. In stress change computation, we take into account nonlinear viscoelastic deformation in the asthenosphere. In the presentation, we will show simulation results in a normative three-dimensional problem, where a circular-shaped velocity-weakening area is set in a square-shaped fault plane. The results with and without nonlinear viscosity in the asthenosphere will be compared. We also plan to apply the developed code to simulate the post-earthquake deformation of a megathrust earthquake, such as the 2011 Tohoku earthquake. Acknowledgment: The results were obtained using the K computer at the RIKEN (Proposal number hp160221).

Effect of Alloy Elements on Microstructures and Mechanical Properties in Al-Mg-Si Alloys

NASA Astrophysics Data System (ADS)

Kato, Yoshikazu; Hisayuki, Koji; Sakaguchi, Masashi; Higashi, Kenji

Microstructures and mechanical properties in the modified Al-Mg-Si alloys with variation in the alloy elements and their contents were investigated to enhance higher strength and ductility. Optimizing both the alloy element design and the industrial processes including heat-treatments and extrusion technology was carried out along the recent suggestion from the first principles calculation. The investigation concluded that the addition of Fe and/or Cu could recovery their lost ductility, furthermore increase their tensile strength up to 420 MPa at high elongation of 24 % after T6 condition for Al-0.8mass%Mg-1.0mass%Si-0.8mass%Cu-0.5mass%Fe alloy with excess Si content. The excellent combination between strength and ductility could be obtained by improvement to the grain boundary embitterment caused by grain boundary segregation of Si as a result from the interaction of Si with Cu or Fe with optimizing the amount of Cu and Fe contents.

Effect of light elements on the sound velocities in solid iron: Implications for the composition of Earth's core

NASA Astrophysics Data System (ADS)

Badro, James; Fiquet, Guillaume; Guyot, François; Gregoryanz, Eugene; Occelli, Florent; Antonangeli, Daniele; d'Astuto, Matteo

2007-02-01

We measured compressional sound velocities in light element alloys of iron (FeO, FeSi, FeS, and FeS2) at high-pressure by inelastic X-ray scattering. This dataset provides new mineralogical constraints on the composition of Earth's core, and completes the previous sets formed by the pressure-density systematics for these compounds. Based on the combination of these datasets and their comparison with radial seismic models, we propose an average composition model of the Earth's core. We show that the incorporation of small amounts of silicon or oxygen is compatible with geophysical observations and geochemical abundances. The effect of nickel on the calculated light element contents is shown to be negligible. The preferred core model derived from our measurements is an inner core which contains 2.3 wt.% silicon and traces of oxygen, and an outer core containing 2.8 wt.% silicon and around 5.3 wt.% oxygen.

COST-EFFECTIVE RARE EARTH ELEMENT RECYCLING PROCESS FROM INDUSTRIAL SCRAP AND DISCARDED ELECTRONIC PRODUCTS TO VALUABLE MAGNETIC ALLOYS AND PERMANENT MAGNETS - PHASE II

EPA Science Inventory

Rare earth element (REE) based Nd-Fe-B and Sm-Co permanent magnets have been widely used because of their excellent magnetic properties. The applications of Nd-Fe-B and Sm-Co rare earth permanent magnets include hybrid electric vehicles (HEVs), power generators for wind tur...

All-soluble all-iron aqueous redox-flow battery

DOE PAGES

Gong, Ke; Xu, Fei; Grunewald, Jonathan B.; ...

2016-05-03

The rapid growth of intermittent renewable energy (e.g., wind and solar) demands low-cost and large-scale energy storage systems for smooth and reliable power output, where redox-flow batteries (RFBs) could find their niche. In this work, we introduce the first all-soluble all-iron RFB based on iron as the same redox-active element but with different coordination chemistries in alkaline aqueous system. The adoption of the same redox-active element largely alleviates the challenging problem of cross-contamination of metal ions in RFBs that use two redox-active elements. An all-soluble all-iron RFB is constructed by combining an iron–triethanolamine redox pair (i.e., [Fe(TEOA)OH] –/[Fe(TEOA)(OH)] 2–) andmore » an iron–cyanide redox pair (i.e., Fe(CN) 6 3–/Fe(CN) 6 4–), creating 1.34 V of formal cell voltage. Furthermore, good performance and stability have been demonstrated, after addressing some challenges, including the crossover of the ligand agent. As exemplified by the all-soluble all-iron flow battery, combining redox pairs of the same redox-active element with different coordination chemistries could extend the spectrum of RFBs.« less

Adaptive finite element modelling of three-dimensional magnetotelluric fields in general anisotropic media

NASA Astrophysics Data System (ADS)

Liu, Ying; Xu, Zhenhuan; Li, Yuguo

2018-04-01

We present a goal-oriented adaptive finite element (FE) modelling algorithm for 3-D magnetotelluric fields in generally anisotropic conductivity media. The model consists of a background layered structure, containing anisotropic blocks. Each block and layer might be anisotropic by assigning to them 3 × 3 conductivity tensors. The second-order partial differential equations are solved using the adaptive finite element method (FEM). The computational domain is subdivided into unstructured tetrahedral elements, which allow for complex geometries including bathymetry and dipping interfaces. The grid refinement process is guided by a global posteriori error estimator and is performed iteratively. The system of linear FE equations for electric field E is solved with a direct solver MUMPS. Then the magnetic field H can be found, in which the required derivatives are computed numerically using cubic spline interpolation. The 3-D FE algorithm has been validated by comparisons with both the 3-D finite-difference solution and 2-D FE results. Two model types are used to demonstrate the effects of anisotropy upon 3-D magnetotelluric responses: horizontal and dipping anisotropy. Finally, a 3D sea hill model is modelled to study the effect of oblique interfaces and the dipping anisotropy.

Autumnal resorption and accretion of trace metals in gallery forest tree. [Quercus macrocarpa, Quercus muehlenbergii, Fraxinus pennsylvanica, Celtis occidentalis, and Ulmus rubra

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

Killingbeck, K.T.

1985-02-01

Autumnal resorption and accretion of copper (Cu), iron (Fe), zinc (Zn), and manganese (Mn) were measured in the foliage of five gallery forest trees species on the Konza Prairie Research Natural Area. Presenescence and postabscission leaves from five trees each of Quercus macrocarpa, Q. muehlenbergii, Fraxinus pennsylvanica, Celtis occidentalis, and Ulmus rubra, were sampled. Three species resorbed 19, 25, and 26%, respectively, of their presenescence foliar Zn, and one species resorbed 35% of its presenescence foliar Fe. This validates the prediction made by others that Zn and Fe are withdrawn from the senescing foliage of at least some deciduous species.more » Net accretions of Cu (43, 44, 69%), Fe (36, 40%), and Mn (19, 57%) occurred during the same period. The two oak species were responsible for most of the resorption, while the three non-oak species accounted for all of the significant accretions. Such well-defined differences in element conservation may influence interspecific competition by accentuating, or compensating for, species differences in element uptake ability and element use efficiency. Demand:availability ratios proved useful in predicting the likelihood that a given element would be conserved through resorption.« less

Constraints on Earth’s inner core composition inferred from measurements of the sound velocity of hcp-iron in extreme conditions

PubMed Central

Sakamaki, Tatsuya; Ohtani, Eiji; Fukui, Hiroshi; Kamada, Seiji; Takahashi, Suguru; Sakairi, Takanori; Takahata, Akihiro; Sakai, Takeshi; Tsutsui, Satoshi; Ishikawa, Daisuke; Shiraishi, Rei; Seto, Yusuke; Tsuchiya, Taku; Baron, Alfred Q. R.

2016-01-01

Hexagonal close-packed iron (hcp-Fe) is a main component of Earth’s inner core. The difference in density between hcp-Fe and the inner core in the Preliminary Reference Earth Model (PREM) shows a density deficit, which implies an existence of light elements in the core. Sound velocities then provide an important constraint on the amount and kind of light elements in the core. Although seismological observations provide density–sound velocity data of Earth’s core, there are few measurements in controlled laboratory conditions for comparison. We report the compressional sound velocity (VP) of hcp-Fe up to 163 GPa and 3000 K using inelastic x-ray scattering from a laser-heated sample in a diamond anvil cell. We propose a new high-temperature Birch’s law for hcp-Fe, which gives us the VP of pure hcp-Fe up to core conditions. We find that Earth’s inner core has a 4 to 5% smaller density and a 4 to 10% smaller VP than hcp-Fe. Our results demonstrate that components other than Fe in Earth’s core are required to explain Earth’s core density and velocity deficits compared to hcp-Fe. Assuming that the temperature effects on iron alloys are the same as those on hcp-Fe, we narrow down light elements in the inner core in terms of the velocity deficit. Hydrogen is a good candidate; thus, Earth’s core may be a hidden hydrogen reservoir. Silicon and sulfur are also possible candidates and could show good agreement with PREM if we consider the presence of some melt in the inner core, anelasticity, and/or a premelting effect. PMID:26933678

Comparative Study of Electronic Structure and Magnetic Properties of Osmate Double Perovskites: Ca2FeOsO6 versus Ca2Co(Ni)OsO6

NASA Astrophysics Data System (ADS)

Samanta, Kartik; Saha-Dasgupta, Tanusri

2018-04-01

Employing density functional theory, we study the trend in the electronic and magnetic properties of 3d-5d double perovskites, upon varying the 3d element for a fixed choice of 5d element, namely Ca2BOsO6 (B = Fe/Co/Ni). While all three compounds are reported to be ferrimagnets, the magnetic transition temperature of Ca2FeOsO6 is reported to be 2-2.4 times larger than that of Ca2CoOsO6 or Ca2NiOsO6. Our first-principles study provides microscopic insight into this trend. This trend is found to be caused by the downward shift in the position of d level energies of the B site element with respect to that of the Os t2g level upon moving across the 3d series from Fe to Co and Ni. This in turn changes the nominal valence of the Os ion from 5+ in Ca2FeOsO6 to 6+ in Ca2CoOsO6 and Ca2NiOsO6, resulting in differing superexchange paths between Ca2FeOsO6 and Ca2Co(Ni)OsO6, and additionally enabling the hybridization-mechanism-driven magnetism in Ca2FeOsO6. These together significantly enhance the magnetic transition temperature in Ca2FeOsO6 compared with that in Ca2Co(Ni)OsO6.

The Abundances of the Fe Group Elements in Early B Stars in the Magellanic Clouds and Our Galaxy

NASA Astrophysics Data System (ADS)

Peters, Geraldine Joan; Adelman, Saul Joseph

2015-08-01

The abundances of the Fe-peak elements (Ti, V, Cr, Mn, Fe, Co, and Ni) are of interest as they are important for assessing opacities for stellar evolution calculations, confirming theoretical calculations of explosive nucleosynthesis, and inferring the past history of supernova activity in a galaxy. FUSE FUV spectra of early B stars in the LMC and SMC and HST/STIS FUV/NUV spectra of nearby B stars in our galaxy are analyzed with the Hubeny/Lanz programs TLUSTY/SYNSPEC to determine abundance for the Fe group elements and produce a map of these abundances in the Magellanic Clouds (MC) and Magellanic Bridge (MB). Except for four weak multiplets of Fe III there are no measurable lines from the Fe group in the optical region. The Fe group species found in the FUV spectra of early B stars are primarily in the second stage of ionization. The best set of lines in the FUSE spectral region are Fe III (UV1), V III 1150 Å, and Cr III 1137 Å. Analysis of the galactic B stars provides a good assessment of the reliability of the atomic parameters that are used for the MC calculations. Twenty-two early B stars in the MC and MB and five in our galaxy were analyzed. In general the Fe group abundances range from solar to slightly below solar in our region of the galaxy. But in the MCs the abundances of V, Cr, and Fe tend to be significantly lower than the mean metal abundances for the galaxy. Maps of the Fe group abundances and their variations in the LMC and SMC, tracers of recent enrichment of the ISM from supernova activity, are shown. Support from NASA grants NAG5-13212, NNX10AD66G, STScI HST-GO-13346.22, and USC’s Women in Science and Engineering (WiSE) program is greatly appreciated.

Studying the Effect of Deposition Conditions on the Performance and Reliability of MEMS Gas Sensors

PubMed Central

Sadek, Khaled; Moussa, Walied

2007-01-01

In this paper, the reliability of a micro-electro-mechanical system (MEMS)-based gas sensor has been investigated using Three Dimensional (3D) coupled multiphysics Finite Element (FE) analysis. The coupled field analysis involved a two-way sequential electrothermal fields coupling and a one-way sequential thermal-structural fields coupling. An automated substructuring code was developed to reduce the computational cost involved in simulating this complicated coupled multiphysics FE analysis by up to 76 percent. The substructured multiphysics model was then used to conduct a parametric study of the MEMS-based gas sensor performance in response to the variations expected in the thermal and mechanical characteristics of thin films layers composing the sensing MEMS device generated at various stages of the microfabrication process. Whenever possible, the appropriate deposition variables were correlated in the current work to the design parameters, with good accuracy, for optimum operation conditions of the gas sensor. This is used to establish a set of design rules, using linear and nonlinear empirical relations, which can be utilized in real-time at the design and development decision-making stages of similar gas sensors to enable the microfabrication of these sensors with reliable operation.

Element-resolved thermodynamics of magnetocaloric LaFe 13 – x Si x

DOE PAGES

Gruner, Markus E.; Keune, Werner; Cuenya, B. Roldan; ...

2015-02-04

By combination of two independent approaches, nuclear resonant inelastic x-ray scattering and first-principles calculations in the framework of density functional theory, we demonstrate significant changes in the element-resolved vibrational density of states across the first-order transition from the ferromagnetic low temperature to the paramagnetic high temperature phase of LaFe 13-xSi x. These changes originate from the itinerant electron metamagnetism associated with Fe and lead to a pronounced magneto-elastic softening despite the large volume decrease at the transition. As a result, the increase in lattice entropy associated with the Fe subsystem is significant and contributes cooperatively with the magnetic and electronicmore » entropy changes to the excellent magneto- and barocaloric properties.« less

Writing analytic element programs in Python.

PubMed

Bakker, Mark; Kelson, Victor A

2009-01-01

The analytic element method is a mesh-free approach for modeling ground water flow at both the local and the regional scale. With the advent of the Python object-oriented programming language, it has become relatively easy to write analytic element programs. In this article, an introduction is given of the basic principles of the analytic element method and of the Python programming language. A simple, yet flexible, object-oriented design is presented for analytic element codes using multiple inheritance. New types of analytic elements may be added without the need for any changes in the existing part of the code. The presented code may be used to model flow to wells (with either a specified discharge or drawdown) and streams (with a specified head). The code may be extended by any hydrogeologist with a healthy appetite for writing computer code to solve more complicated ground water flow problems. Copyright © 2009 The Author(s). Journal Compilation © 2009 National Ground Water Association.

Element Specific Spin and Orbital Moments in Fe1-x Vx Alloys

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

Guan, Y.; Scheck, C; Bailey, W

2009-01-01

We present transmission-mode X-ray magnetic circular dichroism (XMCD) measurements of element-specific magnetic moments for Fe and V at the L2,3 edges in polycrystalline Fe1-xVx ultrathin films. We find that the orbital-to-spin moment ratio of Fe does not change within experimental error. The V XMCD is not very informative, and a nearly pure-spin type V impurity moment ({approx}1.0 {mu}{sub B}/atom, antiparallel to the Fe host moment) is assumed to match known magnetization data. Data are further reduced to a two-sublattice model and found to be compatible with known spectroscopic splitting g-factor data in the alloy. The results confirm that the verymore » low Gilbert damping, attained through the introduction of V into epitaxial Fe1-xVx films and found by ferromagnetic resonance (FMR), does not result from the reduction of orbital moment content in the alloy.« less

Energetic particle abundances in solar electron events

NASA Technical Reports Server (NTRS)

Reames, D. V.; Cane, H. V.; Von Rosenvinge, T. T.

1990-01-01

The results of a comprehensive search of the ISEE 3 energetic particle data for solar electron events with associated increases in elements with atomic number Z = 6 or greater are reported. A sample of 90 such events was obtained. The events support earlier evidence of a bimodal distribution in Fe/O or, more clearly, in Fe/C. Most of the electron events belong to the group that is Fe-rich in comparison with the coronal abundance. The Fe-rich events are frequently also He-3-rich and are associated with type III and type V radio bursts and impulsive solar flares. Fe-poor events are associated with type IV bursts and with interplanetary shocks. With some exceptions, event-to-event enhancements in the heavier elements vary smoothly with Z and with Fe/C. In fact, these variations extend across the full range of events despite inferred differences in acceleration mechanism. The origin of source material in all events appears to be coronal and not photospheric.

Potential human health risk from consumption of metallic elements-contaminated benthic mollusks from Don Hoi Lot sandbar, Thailand.

PubMed

Khidkhan, Kraisiri; Imsilp, Kanjana; Poapolathep, Amnart; Poapolathep, Saranya; Tanhan, Phanwimol

2017-04-15

Environmental pollutants have raised more concerns for human health risk, especially via consumption of contaminated food. Terrestrial as well as aquatic animals are capable of bioaccumulation a variety of toxic substances including metallic elements. With increasing anthropogenic activities along the coastal areas, living organisms have more chances to be exposed to released contaminants. In this study, seven metallic elements (Cd, Cu, Fe, Mn, Ni, Pb and Zn) were determined in sediments and water from Don Hoi Lot sandbar, Samutsongkharm province, Thailand. Potential human health risks via the consumption of two benthic bivalves Solen corneus (Larmarck, 1818) and Meretrix meretrix (Linnaeus, 1758) were also estimated using the target hazard quotients (THQs). The variations of metallic element concentrations were apparent between wet and dry season. Fe was the predominate metallic element in the sediment and the remaining were Mn>Pb>Zn>Ni>Cu>Cd. Whereas metallic element concentrations in water were Pb>Ni>Fe>Zn>Cu>Mn>Cd. PCA analysis confirmed that the contaminations of these metallic elements were from Mae Klong river surface water. Most Pb THQ values in both S. corneus and M. meretrix were >1 indicating that human health risk is of concern. However, the sum of THQs of an individual metallic element should also be considered since multiple metallic elements exposure is so common. Copyright © 2017 Elsevier B.V. All rights reserved.

Inferring episodic atmospheric iron fluxes in the Western South Atlantic

NASA Astrophysics Data System (ADS)

Evangelista, Heitor; Maldonado, Juan; dos Santos, Elaine A.; Godoi, Ricardo H. M.; Garcia, Carlos A. E.; Garcia, Virginia M. T.; Jonhson, Erling; Dias da Cunha, Kenya; Leite, Carlos Barros; Van Grieken, René; Van Meel, Katleen; Makarovska, Yaroslava; Gaiero, Diego M.

2010-02-01

Iron (Fe) and other trace elements such as Zn, Mn, Ni and Cu are known as key-factors in marine biogeochemical cycles. It is believed that ocean primary productivity blooms in iron deficient regions can be triggered by iron in aeolian dust. Up to now, scarce aerosol elemental composition, based on measurements over sea at the Western South Atlantic (WSA), exist. An association between the Patagonian semi-desert dust/Fe and chlorophyll-a variability at the Argentinean continental shelf is essentially inferred from models. We present here experimental data of Fe enriched aerosols over the WSA between latitudes 22°S-62°S, during 4 oceanographic campaigns between 2002 and 2005. These data allowed inferring the atmospheric Fe flux onto different latitudinal bands which varied from 30.4 to 1688 nmolFe m -2 day -1 (October 29th-November 15th, 2003); 5.83-1586 nmolFe m -2 day -1 (February 15th-March 6th, 2004) and 4.73-586 nmolFe m -2 day -1(October 21st-November 5th, 2005).

Calculations of the energy levels and oscillator strengths of the Ne-like Fe Ion (Fe XVII)

NASA Astrophysics Data System (ADS)

Zhong, Jia-yong; Zhang, Jie; Zhao, Gang; Lu, Xin

Energy levels and oscillator strengths among the 27 fine-structure levels belonging to the (ls 22s 2)2p 6, 2p 53s, 2p 53p and 2p 53d configurations of the neon-like iron ion have been calculated using three atomic structure codes RCN/RCG, AUTOSTRUCTURE (AS) and GRASP. Relativistic corrections of the wave functions are taken into account in the RCN/RCG calculation. The results agree well with the available experimental and theoretical data. The accuracy of the three codes is analysed.

Phase transformation and magnetic properties of MnAl powders prepared by elemental-doping and salt-assisted ball milling

NASA Astrophysics Data System (ADS)

Qian, Hui-Dong; Si, Ping-Zhan; Choi, Chul-Jin; Park, Jihoon; Cho, Kyung Mox

2018-05-01

The effects of elemental doping of Si and Fe on the ɛ→τ phase transformation and the magnetic properties of MnAl were studied. The magnetic powders of Si- and Fe-doped MnAl were prepared by using induction melting followed by water-quenching, annealing, and salt-assisted ball-milling. The Fe-doped MnAl powders are mainly composed of the L10-structured τ-phase, while the Si-doped MnAl are composed of τ-phase and a small fraction of γ2- and β-phases. A unique thin leaves-like morphology with thickness of several tens of nanometers and diameter size up to 500 nm were observed in the Si-doped MnAl powders. The Fe-doped MnAl powders show irregular shape with much larger dimensions in the range from several to 10 μm. The morphology difference of the samples was ascribed to the variation of the mechanical properties affected by different doping elements. The phase transformation temperatures of the ɛ-phase of the samples were measured. The doping of Fe decreases the onset temperature of the massive phase transformation in MnAl, while the Si-doping increases the massive phase transformation temperature. Both Fe and Si increase the Curie temperature of MnAl. A substantially enhanced coercivity up to 0.45 T and 0.42 T were observed in the ball-milled MnAl powders doped with Si and Fe, respectively.

Southern Ocean biological iron cycling in the pre-whaling and present ecosystems

NASA Astrophysics Data System (ADS)

Maldonado, Maria T.; Surma, Szymon; Pakhomov, Evgeny A.

2016-11-01

This study aimed to create the first model of biological iron (Fe) cycling in the Southern Ocean food web. Two biomass mass-balanced Ecopath models were built to represent pre- and post-whaling ecosystem states (1900 and 2008). Functional group biomasses (tonnes wet weight km-2) were converted to biogenic Fe pools (kg Fe km-2) using published Fe content ranges. In both models, biogenic Fe pools and consumption in the pelagic Southern Ocean were highest for plankton and small nektonic groups. The production of plankton biomass, particularly unicellular groups, accounted for the highest annual Fe demand. Microzooplankton contributed most to biological Fe recycling, followed by carnivorous zooplankton and krill. Biological Fe recycling matched previous estimates, and, under most conditions, could entirely meet the Fe demand of bacterioplankton and phytoplankton. Iron recycling by large baleen whales was reduced 10-fold by whaling between 1900 and 2008. However, even under the 1900 scenario, the contribution of whales to biological Fe recycling was negligible compared with that of planktonic consumers. These models are a first step in examining oceanic-scale biological Fe cycling, highlighting gaps in our present knowledge and key questions for future research on the role of marine food webs in the cycling of trace elements in the sea. This article is part of the themed issue 'Biological and climatic impacts of ocean trace element chemistry'.

Coping with Iron Limitation: A Metabolomic Study of Synechocystis sp. PCC 6803.

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

Rivas-Ubach, Albert; Poret-Peterson, A. T.; Penuel

2018-02-28

Iron (Fe) is a key element for all living systems, especially for photosynthetic organisms because of its important role in the photosynthetic electron transport chain. Fe limitation in cyanobacteria leads to several physiological and morphological changes. However, the overall metabolic responses to Fe limitation are still poorly understood. In this study, we integrated elemental, stoichiometric, macromolecular, and metabolomic data to shed light on the responses of Synechocystis sp. PCC 6803, a non-N2-fixing freshwater cyanobacterium, to Fe limitation. Compared to Synechocystis growing at nutrient replete conditions, Fe-limited cultures had lower growth rates and amounts of chlorophyll a, RNA, RNA:DNA, C, N,more » and P and higher ratios of Protein:RNA, C:N, C:P and N:P, in accordance with the growth rate hypothesis which predicts faster growing organisms will have decreased biomass RNA contents and C:P and N:P ratios. Fe-limited Synechocystis had lower amounts Fe, Mn and Mo, and higher amount of Cu. Several changes in amino acids of cultures growing under Fe limitation suggest nitrogen limitation. Additionally, we found substantial increases in stress-related metabolites in Fe-limited cyanobacteria such antioxidants. This study represents an advance in understanding the stoichiometric, macromolecular and metabolic strategies that cyanobacteria use to cope with Fe limitation. This information, moreover, may further understanding of changes in cyanobacterial functions under scenarios of Fe limitation in aquatic ecosystems.« less

Biogeochemical Cycling of Fe, S, C, N, and Mo in the 3.2 Ga ocean: Constraints from DXCL-DP Black Shales from Pilbara, Western Australia

NASA Astrophysics Data System (ADS)

Yamaguchi, K. E.; Naraoka, H.; Ikehara, M.; Ito, T.; Kiyokawa, S.

2014-12-01

Records of geochemical cycling of bio-essential, redox-sensitive elements have keys to decipher mysteries of the co-evolution of Earth and life. To obtain insight into biogeochemical cycling of those elements and early evolution of microbial biosphere from high-quality samples, we drilled through Mesoarchean strata in coastal Pilbara (Dixon Island-Cleaverville Drilling Project, see Yamaguchi et al., 2009; Kiyokawa et al., 2012), and obtained 3.2 Ga old drillcores (CL1, CL2, and DX) of sulfide-rich black shales in the Cleaverville Group, Pilbara Supergroup. We conducted a systematic geochemical study involving sequential extractions of Fe, S, C, and N for phase-dependent contents (e.g., pyrite-Fe, reactive-Fe, highly reactive-Fe, unreactive-Fe, pyrite-S, sulfate-S, organic-S, elemental-S, Corg, Ccarb, Norg, and Nclay) and their stable isotope compositions, micro FT-IR and laser Raman spectroscopy for extracted kerogen, in addition to major and trace (redox-sensitive; e.g., Mo) element analysis, for >100 samples. Here we integrate our recent multidisciplinary investigations into the redox state of ocean and nature of microbial biosphere in the ocean 3.2 Ga ago. All of the obtained data are very difficult to explain only by geochemical processes in strictly anoxic environments, where both atmosphere and oceans were completely anoxic, like an environment before the inferred "Great Oxidation Event" when pO2 was lower than 0.00001 PAL (e.g., Holland, 1994). Our extensive data set consistently suggests that oxygenic photosynthesis, bacterial sulfate reduction, and microbially mediated redox-cycling of nitrogen, possibly involving denitrification and N2-fixation, are very likely to have been operating, and may be used as a strong evidence for at least local and temporal existence of oxidized environment as far back as 3.2 Ga ago. Modern-style biogeochemical cycling of Fe, S, C, N, and Mo has been operating since then. The atmosphere-hydrosphere system 3.2 Ga ago would have been sufficiently oxidized to allow redox-cycling of elements during deposition of the sediments, ~800 Ma earlier than commonly thought. Our suggestions have far-reaching and astrobiological implications for earlier evolution of the surface environment, especially redox state, and marine microbial biosphere.

Phase identification in boron-containing powder metallurgy steel using EBSD in combination with EPMA

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

Wu, Ming-Wei, E-mail: mwwu@ntut.edu.tw; Cai, Wen-Zhang

2016-03-15

Boron (B) is extensively used to induce liquid phase sintering (LPS) in powder metallurgy (PM) steels and thereby increase the densification. The alloying elements in B-containing PM steels affect the boride phase, stability of the boride, the temperature of liquid formation, and the progress of LPS. However, the boride phase has not been systematically identified yet. The main objective of this study was to clarify the influences of alloying elements, including C, Cr, and Ni, on the boride phases using electron backscatter diffraction (EBSD) in combination with electron probe microanalysis (EPMA). Network structures consisting of ferrite, Fe{sub 2}B boride, andmore » Fe{sub 3}C carbide were extensively observed in the Fe–0.4B–0.5C steel. The portions of Fe{sub 2}B were sufficiently larger than those of Fe{sub 3}C, and Fe{sub 3}C was mostly distributed at the interfaces between ferrite and Fe{sub 2}B. Adding 1.5 wt.% Cr or 1.8 wt.% Ni to Fe–0.4B–0.5C steel completely changes the Fe{sub 2}B and Fe{sub 3}C phases to a M{sub 3}(B,C) phase, where M represents the metallic elements, including Fe, Cr, Mo, and Ni. Furthermore, Cr, Mo, B, and C atoms tend to concentrate on the M{sub 3}(B,C) phase, but Ni atoms do not. - Highlights: • Network structures consisting of ferrite, Fe{sub 2}B boride, and Fe{sub 3}C carbide were extensively observed in the Fe–0.4B–0.5C steel. • Adding 1.5 wt.% Cr or 1.8 wt.% Ni to Fe–0.4B–0.5C steel completely transforms the Fe{sub 2}B and Fe{sub 3}C phases to a M{sub 3}(B,C) phase. • Cr, Mo, B, and C atoms tend to concentrate on the M{sub 3}(B,C) phase, but Ni atoms do not.« less

Finite element simulation and Experimental verification of Incremental Sheet metal Forming

NASA Astrophysics Data System (ADS)

Kaushik Yanamundra, Krishna; Karthikeyan, R., Dr.; Naranje, Vishal, Dr

2018-04-01

Incremental sheet metal forming is now a proven manufacturing technique that can be employed to obtain application specific, customized, symmetric or asymmetric shapes that are required by automobile or biomedical industries for specific purposes like car body parts, dental implants or knee implants. Finite element simulation of metal forming process is being performed successfully using explicit dynamics analysis of commercial FE software. The simulation is mainly useful in optimization of the process as well design of the final product. This paper focuses on simulating the incremental sheet metal forming process in ABAQUS, and validating the results using experimental methods. The shapes generated for testing are of trapezoid, dome and elliptical shapes whose G codes are written and fed into the CNC milling machine with an attached forming tool with a hemispherical bottom. The same pre-generated coordinates are used to simulate a similar machining conditions in ABAQUS and the tool forces, stresses and strains in the workpiece while machining are obtained as the output data. The forces experimentally were recorded using a dynamometer. The experimental and simulated results were then compared and thus conclusions were drawn.

Dysprosium-free melt-spun permanent magnets.

PubMed

Brown, D N; Wu, Z; He, F; Miller, D J; Herchenroeder, J W

2014-02-12

Melt-spun NdFeB powders can be formed into a number of different types of permanent magnet for a variety of applications in electronics, automotive and clean technology industries. The melt-spinning process produces flake powder with a fine uniform array of nanoscale Nd2Fe14B grains. These powders can be net-shape formed into isotropic polymer-bonded magnets or hot formed into fully dense magnets. This paper discusses the influence of heavy rare earth elements and microstructure on the magnetic performance, thermal stability and material cost of NdFeB magnets. Evidence indicates that melt-spun nanocrystalline NdFeB magnets are less dependent on heavy rare earth elements for high-temperature performance than the alternative coarser-grained sintered NdFeB magnets. In particular, hot-pressed melt-spun magnets are an attractive low-cost solution for applications that require thermal stability up to 175-200 °C.

Modeling the global emission, transport and deposition of trace elements associated with mineral dust

DOE PAGES

Zhang, Y.; Mahowald, N.; Scanza, R. A.; ...

2015-10-12

Trace element deposition from desert dust has important impacts on ocean primary productivity, the quantification of which could be useful in determining the magnitude and sign of the biogeochemical feedback on radiative forcing. However, the impact of elemental deposition to remote ocean regions is not well understood and is not currently included in global climate models. In this study, emission inventories for eight elements primarily of soil origin, Mg, P, Ca, Mn, Fe, K, Al, and Si are determined based on a global mineral data set and a soil data set. The resulting elemental fractions are used to drive themore » desert dust model in the Community Earth System Model (CESM) in order to simulate the elemental concentrations of atmospheric dust. Spatial variability of mineral dust elemental fractions is evident on a global scale, particularly for Ca. Simulations of global variations in the Ca / Al ratio, which typically range from around 0.1 to 5.0 in soils, are consistent with observations, suggesting that this ratio is a good signature for dust source regions. The simulated variable fractions of chemical elements are sufficiently different; estimates of deposition should include elemental variations, especially for Ca, Al and Fe. The model results have been evaluated with observations of elemental aerosol concentrations from desert regions and dust events in non-dust regions, providing insights into uncertainties in the modeling approach. The ratios between modeled and observed elemental fractions range from 0.7 to 1.6, except for Mg and Mn (3.4 and 3.5, respectively). Using the soil database improves the correspondence of the spatial heterogeneity in the modeling of several elements (Ca, Al and Fe) compared to observations. Total and soluble dust element fluxes to different ocean basins and ice sheet regions have been estimated, based on the model results. The annual inputs of soluble Mg, P, Ca, Mn, Fe and K associated with dust using the mineral data set are 0.30 Tg, 16.89 Gg, 1.32 Tg, 22.84 Gg, 0.068 Tg, and 0.15 Tg to global oceans and ice sheets.« less

Morphing the feature-based multi-blocks of normative/healthy vertebral geometries to scoliosis vertebral geometries: development of personalized finite element models.

PubMed

Hadagali, Prasannaah; Peters, James R; Balasubramanian, Sriram

2018-03-01

Personalized Finite Element (FE) models and hexahedral elements are preferred for biomechanical investigations. Feature-based multi-block methods are used to develop anatomically accurate personalized FE models with hexahedral mesh. It is tedious to manually construct multi-blocks for large number of geometries on an individual basis to develop personalized FE models. Mesh-morphing method mitigates the aforementioned tediousness in meshing personalized geometries every time, but leads to element warping and loss of geometrical data. Such issues increase in magnitude when normative spine FE model is morphed to scoliosis-affected spinal geometry. The only way to bypass the issue of hex-mesh distortion or loss of geometry as a result of morphing is to rely on manually constructing the multi-blocks for scoliosis-affected spine geometry of each individual, which is time intensive. A method to semi-automate the construction of multi-blocks on the geometry of scoliosis vertebrae from the existing multi-blocks of normative vertebrae is demonstrated in this paper. High-quality hexahedral elements were generated on the scoliosis vertebrae from the morphed multi-blocks of normative vertebrae. Time taken was 3 months to construct the multi-blocks for normative spine and less than a day for scoliosis. Efforts taken to construct multi-blocks on personalized scoliosis spinal geometries are significantly reduced by morphing existing multi-blocks.

Trace element and strontium isotope characteristics of volcanic rocks from Isla Tortuga: a young seamount in the Gulf of California

USGS Publications Warehouse

Batiza, Rodey; Futa, K.; Hedge, C.E.

1979-01-01

Isla Tortuga is a small isolated central volcano which is located near an actively spreading trough in the Gulf of California. The basalt lavas from Tortuga which have the highest Mg/Fe and Ni contents have trace element abundances and ratios and 87Sr/86Sr which are similar to those of mid-ocean ridge tholeiite. The major element, rare earth element and Sr abundances of fractionated tholeiite (low Mg/Fe) and tholeiitic andesite of Tortuga are consistent with an origin by closed-system fractional crystallization. This hypothesis is not supported by K, Na, Rb and Ba abundances in the lavas nor by their variable 87Sr/86Sr (0.7024-0.7035). It is proposed that the apparent decoupling of light rare earth elements, other incompatible trace elements and 87Sr/86Sr is due to contamination of some Tortuga magmas while they are fractionated in a high-level crustal magma chamber. The mantle source of least-contaminated, high Mg/Fe basalt lavas of Tortuga is similar, although not identical to the source of normal mid-ocean ridge tholeiite; significant differences exist. The reasons for these differences are not yet known. ?? 1979.

SECIS elements in the coding regions of selenoprotein transcripts are functional in higher eukaryotes

PubMed Central

Mix, Heiko; Lobanov, Alexey V.; Gladyshev, Vadim N.

2007-01-01

Expression of selenocysteine (Sec)-containing proteins requires the presence of a cis-acting mRNA structure, called selenocysteine insertion sequence (SECIS) element. In bacteria, this structure is located in the coding region immediately downstream of the Sec-encoding UGA codon, whereas in eukaryotes a completely different SECIS element has evolved in the 3′-untranslated region. Here, we report that SECIS elements in the coding regions of selenoprotein mRNAs support Sec insertion in higher eukaryotes. Comprehensive computational analysis of all available viral genomes revealed a SECIS element within the ORF of a naturally occurring selenoprotein homolog of glutathione peroxidase 4 in fowlpox virus. The fowlpox SECIS element supported Sec insertion when expressed in mammalian cells as part of the coding region of viral or mammalian selenoproteins. In addition, readthrough at UGA was observed when the viral SECIS element was located upstream of the Sec codon. We also demonstrate successful de novo design of a functional SECIS element in the coding region of a mammalian selenoprotein. Our data provide evidence that the location of the SECIS element in the untranslated region is not a functional necessity but rather is an evolutionary adaptation to enable a more efficient synthesis of selenoproteins. PMID:17169995

Robust Hybrid Finite Element Methods for Antennas and Microwave Circuits

NASA Technical Reports Server (NTRS)

Gong, J.; Volakis, John L.

1996-01-01

One of the primary goals in this dissertation is concerned with the development of robust hybrid finite element-boundary integral (FE-BI) techniques for modeling and design of conformal antennas of arbitrary shape. Both the finite element and integral equation methods will be first overviewed in this chapter with an emphasis on recently developed hybrid FE-BI methodologies for antennas, microwave and millimeter wave applications. The structure of the dissertation is then outlined. We conclude the chapter with discussions of certain fundamental concepts and methods in electromagnetics, which are important to this study.

Insights into Mercury's interior structure from geodesy measurements

NASA Astrophysics Data System (ADS)

Rivoldini, A.; Van Hoolst, T.; Trinh, A.

2013-09-01

The measurements of the gravitational field of Mercury by MESSENGER [1] and improved measurements of the spin state of Mercury [2] provide important constraints on the interior structure of Mercury. In particular, these data give strong constraints on the radius and density of Mercury's core and on the core's concentration of sulfur if sulfur is the only light element in the core [3]. Although sulfur is ubiquitously invoked as being the principal candidate light element in terrestrial planet's cores its abundance in the core depends on the redox conditions during planetary formation. MESSENGER data from remote sensing of Mercury's surface [4] indicate a high abundance of sulfur and confirm the low abundance in FeO supporting the hypotheses that Mercury formed under reducing conditions [5]. Therefore, substantial amounts of other light elements like for instance silicon could be present together with sulfur inside Mercury's core. Unlike sulfur, which does almost not partition into solid iron under Mercury's core pressure and temperature conditions, silicon partitions virtually equally between solid and liquid iron. Thus, if silicon is the only light element inside the core, the density jump at the inner-core outer-core boundary is significantly smaller if compared to an Fe - FeS core. If both silicon and sulfur are present inside Mercury's core then as a consequence of a large immiscibility region in liquid Fe - Si - S at Mercury's core conditions and for specific concentrations of light elements [6] a thin layer much enriched in sulfur and depleted in silicon could form at the top of the core. In this study we analyze interior structure models with silicon as the only light element in the core and with both silicon and sulfur in the core. Compared to models with Fe - FeS both settings have different mass distributions within their cores and will likely deform differently due to different elastic properties. Consequently their libration and tides will be different. Here we will use the measured 88 day libration amplitude and polar moment of inertia of Mercury in order to constrain the interior structure of both settings and calculate their tides.

The Role of Anionogenic Elements (As, Sb, Mo, Se, S, P, N, Cl, F, C) In The Formation of Technogenic Geochemical Anomalies

NASA Astrophysics Data System (ADS)

Abrosimova, Natalya; Bortnikova, Svetlana

2017-12-01

The study was conducted on the example of sulphide-containing mine tailings with a varying amount of sulphide and arsenide minerals, from three distinct tailings dumps situated in Russia: Karabash Mine Site, South Ural; Komsomolsk tailings impoundment, Kemerovo region; Khovu-Aksy mine site, Tuva Republic. The aim of the study was to compare the mobility of anionogenic elements (As, Sb, Mo, Se, S, P, N, Cl, F, C) and their role in migration, precipitation, and concentration of metals during the water-tailings interaction depending on the physicochemical parameters (pH, Eh) of the medium and the mineral composition of the waste material. Using slightly acidic leaching experiments the quantitative estimation of mobile forms of elements is given. Based on the compositions of the obtained water leaching solutions, aqueous speciation of chemical elements and saturation index of key minerals in the experimental solutions were calculated. The results of calculating forms of chemical elements made it possible to construct series of mobility of metals and metalloids in solutions with different physicochemical parameters. In the alkaline conditions, Sb>As>Cd>Cu>Zn>Fe>Pb, when the medium is acidified, the series changes, As>Cd>Cu>Zn>Pb>Sb>Fe in weakly alkaline conditions, Sb>Mn>As>Zn>Fe however, when the medium is acidified, the series changes to Cd>Mn>Pb>Cu>Zn>Sb>Ni>Fe>As under acidic conditions Cd>Cu>Zn>Pb>Mn>Fe>Se>Mo>Sb>As>Ni. The mineral composition of the tailings was investigated, which will allow to determine the sources of toxic elements and to understand the processes of secondary mineral formation in technogenic objects. Arsenopyrite and pyrite predominate in the heavy fraction of the Komsomolsk tailings impoundment, arsenopyrite grains are often corroded, Sb contained in Sb oxide and Sb sulfide. The pyrite and barite are determined in the solid matter of the Karabash Mine Site and chalcopyrite, sphalerite, tennantite Cu3AsS3, and tetrahedrite (Cu,Fe)12Sb4S13 are determined in the form of inclusions in grains of pyrite.

Chemical fractionation of arsenic and heavy metals in fine particle matter and its implications for risk assessment: A case study in Nanjing, China

NASA Astrophysics Data System (ADS)

Li, Huiming; Wang, Jinhua; Wang, Qin'geng; Qian, Xin; Qian, Yu; Yang, Meng; Li, Fengying; Lu, Hao; Wang, Cheng

2015-02-01

A four-step sequential extraction procedure was used to study the chemical fractionation of As and heavy metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) in fine particulate matter (PM2.5) collected from Nanjing, China. The mass concentrations of most PM2.5 samples exceeded the 24 h standard (75 μg/m3) recommended by the new national ambient air quality standard of China. The most abundant elements were Fe, Zn and Pb, while As and Cd were present at the lowest concentrations. As, Cd, Cu, Mn, Pb and Zn were mostly present in the two mobile fractions, including the soluble and exchangeable fraction (F1), and carbonates, oxides and reducible fraction (F2). Fe had the highest proportion present in the residual fraction (F4). Relatively high proportions of the metals Ni and Cr were present in the oxidizable and sulfidic fraction (F3). High proportions of Zn, As and Cu and lower proportions of Cd, Cr and Fe were present in the potentially mobile phases. The enrichment factor, contamination factor and risk assessment code were calculated to analyze the main sources and assess the environmental risks of the metals in PM2.5. The carcinogenic risks of As, Cd, Ni and Pb were all lower than the accepted criterion of 10-6, whereas the carcinogenic risks of Cr for children and As and Cr for adults were higher than 10-6. The non-carcinogenic health risk of As and heavy metals because of PM2.5 exposure for children and adults were lower than but close to the safe level of 1.

BODYFIT-1FE: a computer code for three-dimensional steady-state/transient single-phase rod-bundle thermal-hydraulic analysis. Draft report

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

Chen, B.C.J.; Sha, W.T.; Doria, M.L.

1980-11-01

The governing equations, i.e., conservation equations for mass, momentum, and energy, are solved as a boundary-value problem in space and an initial-value problem in time. BODYFIT-1FE code uses the technique of boundary-fitted coordinate systems where all the physical boundaries are transformed to be coincident with constant coordinate lines in the transformed space. By using this technique, one can prescribe boundary conditions accurately without interpolation. The transformed governing equations in terms of the boundary-fitted coordinates are then solved by using implicit cell-by-cell procedure with a choice of either central or upwind convective derivatives. It is a true benchmark rod-bundle code withoutmore » invoking any assumptions in the case of laminar flow. However, for turbulent flow, some empiricism must be employed due to the closure problem of turbulence modeling. The detailed velocity and temperature distributions calculated from the code can be used to benchmark and calibrate empirical coefficients employed in subchannel codes and porous-medium analyses.« less

Phase constitution in the interfacial region of laser penetration brazed magnesium–steel joints

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

Miao, Yugang; Han, Duanfeng, E-mail: handuanfeng@gmail.com; Xu, Xiangfang

2014-07-01

The phase constitution in the interfacial region of laser penetration brazed magnesium–steel joints was investigated using electron microscopy. From the distribution of elements, the transition zone was mainly composed of elements Mg and Fe along with some Al and O. Furthermore, the transition layer consisted mainly of intermetallic compounds and metal oxides. The compounds were identified as Al-rich phases, such as Mg{sub 17}Al{sub 12}, Mg{sub 2}Al{sub 3}, FeAl and Fe{sub 4}Al{sub 13}. More noteworthy was that the thickness of the transition layer was determined by Fe–Al compounds. The presence of FeAl and Fe{sub 4}Al{sub 13} was a result of themore » complex processes that were associated with the interfacial reaction of solid steel and liquid Mg–Al alloy. - Highlights: • A technology of laser penetration brazed Mg alloy and steel has been developed. • The interface of Mg/Fe dissimilar joints was investigated using electron microscopy. • The transition layer consisted of intermetallic compounds and metal oxides. • Moreover, the thickness of transition layer was determined by Fe/Al compounds. • The presence of FeAl and Fe{sub 4}Al{sub 13} was associated with the interfacial reaction.« less

The Distribution of Dissolved Iron in the West Atlantic Ocean

PubMed Central

Rijkenberg, Micha J. A.; Middag, Rob; Laan, Patrick; Gerringa, Loes J. A.; van Aken, Hendrik M.; Schoemann, Véronique; de Jong, Jeroen T. M.; de Baar, Hein J. W.

2014-01-01

Iron (Fe) is an essential trace element for marine life. Extremely low Fe concentrations limit primary production and nitrogen fixation in large parts of the oceans and consequently influence ocean ecosystem functioning. The importance of Fe for ocean ecosystems makes Fe one of the core chemical trace elements in the international GEOTRACES program. Despite the recognized importance of Fe, our present knowledge of its supply and biogeochemical cycle has been limited by mostly fragmentary datasets. Here, we present highly accurate dissolved Fe (DFe) values measured at an unprecedented high intensity (1407 samples) along the longest full ocean depth transect (17500 kilometers) covering the entire western Atlantic Ocean. DFe measurements along this transect unveiled details about the supply and cycling of Fe. External sources of Fe identified included off-shelf and river supply, hydrothermal vents and aeolian dust. Nevertheless, vertical processes such as the recycling of Fe resulting from the remineralization of sinking organic matter and the removal of Fe by scavenging still dominated the distribution of DFe. In the northern West Atlantic Ocean, Fe recycling and lateral transport from the eastern tropical North Atlantic Oxygen Minimum Zone (OMZ) dominated the DFe-distribution. Finally, our measurements showed that the North Atlantic Deep Water (NADW), the major driver of the so-called ocean conveyor belt, contains excess DFe relative to phosphate after full biological utilization and is therefore an important source of Fe for biological production in the global ocean. PMID:24978190

Exposure of women to trace elements through the skin by direct contact with underwear clothing.

PubMed

Nguyen, Thao; Saleh, Mahmoud A

2017-01-02

Heavy metals pose a potential danger to human health when present in textile materials. In the present study, inductive coupled plasma mass spectrometry (ICPMS) was used to determine the concentrations and the identity of extractable inorganic elements from different brands of women undergarments. A total of 120 samples consisting of 63 cottons, 44 nylons and 13 polyesters manufactured in 14 different countries having different colors were analyzed for their extractable metals contents. Elements analyzed were Ag, Al, As, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Li, Mg, Mn, Na, Ni, Pb, Sb, Se, Sr, Ti, V and Zn. Cotton undergarments were rich in Al, Fe and Zn, nylon undergarments had high levels of Cr, Cu and Al, while polyester fabrics contained higher levels of Ni and Fe compared to cotton or nylon. With respect to manufacturing countries, China, Egypt and India showed the highest concentrations of metals in all fabrics. With respect to the color, black garments were characteristic by high concentration of Fe, blue colors with Cu, brown garments with Fe and Cu, green garments with Cu and Fe, pink garments with Al, purple garments with Al and Cu and red garments with Cr, Zn and Al. The consumer should be made aware of the potential dangers of these metals in their clothing.

Shunted Piezoelectric Vibration Damping Analysis Including Centrifugal Loading Effects

NASA Technical Reports Server (NTRS)

Min, James B.; Duffy, Kirsten P.; Provenza, Andrew J.

2011-01-01

Excessive vibration of turbomachinery blades causes high cycle fatigue problems which require damping treatments to mitigate vibration levels. One method is the use of piezoelectric materials as passive or active dampers. Based on the technical challenges and requirements learned from previous turbomachinery rotor blades research, an effort has been made to investigate the effectiveness of a shunted piezoelectric for the turbomachinery rotor blades vibration control, specifically for a condition with centrifugal rotation. While ample research has been performed on the use of a piezoelectric material with electric circuits to attempt to control the structural vibration damping, very little study has been done regarding rotational effects. The present study attempts to fill this void. Specifically, the objectives of this study are: (a) to create and analyze finite element models for harmonic forced response vibration analysis coupled with shunted piezoelectric circuits for engine blade operational conditions, (b) to validate the experimental test approaches with numerical results and vice versa, and (c) to establish a numerical modeling capability for vibration control using shunted piezoelectric circuits under rotation. Study has focused on a resonant damping control using shunted piezoelectric patches on plate specimens. Tests and analyses were performed for both non-spinning and spinning conditions. The finite element (FE) shunted piezoelectric circuit damping simulations were performed using the ANSYS Multiphysics code for the resistive and inductive circuit piezoelectric simulations of both conditions. The FE results showed a good correlation with experimental test results. Tests and analyses of shunted piezoelectric damping control, demonstrating with plate specimens, show a great potential to reduce blade vibrations under centrifugal loading.

Simulated Response of a Tissue-equivalent Proportional Counter on the Surface of Mars.

PubMed

Northum, Jeremy D; Guetersloh, Stephen B; Braby, Leslie A; Ford, John R

2015-10-01

Uncertainties persist regarding the assessment of the carcinogenic risk associated with galactic cosmic ray (GCR) exposure during a mission to Mars. The GCR spectrum peaks in the range of 300(-1) MeV n to 700 MeV n(-1) and is comprised of elemental ions from H to Ni. While Fe ions represent only 0.03% of the GCR spectrum in terms of particle abundance, they are responsible for nearly 30% of the dose equivalent in free space. Because of this, radiation biology studies focusing on understanding the biological effects of GCR exposure generally use Fe ions. Acting as a thin shield, the Martian atmosphere alters the GCR spectrum in a manner that significantly reduces the importance of Fe ions. Additionally, albedo particles emanating from the regolith complicate the radiation environment. The present study uses the Monte Carlo code FLUKA to simulate the response of a tissue-equivalent proportional counter on the surface of Mars to produce dosimetry quantities and microdosimetry distributions. The dose equivalent rate on the surface of Mars was found to be 0.18 Sv y(-1) with an average quality factor of 2.9 and a dose mean lineal energy of 18.4 keV μm(-1). Additionally, albedo neutrons were found to account for 25% of the dose equivalent. It is anticipated that these data will provide relevant starting points for use in future risk assessment and mission planning studies.

A finite-element simulation of galvanic coupling intra-body communication based on the whole human body.

PubMed

Song, Yong; Zhang, Kai; Hao, Qun; Hu, Lanxin; Wang, Jingwen; Shang, Fuzhou

2012-10-09

Simulation based on the finite-element (FE) method plays an important role in the investigation of intra-body communication (IBC). In this paper, a finite-element model of the whole body model used for the IBC simulation is proposed and verified, while the FE simulation of the galvanic coupling IBC with different signal transmission paths has been achieved. Firstly, a novel finite-element method for modeling the whole human body is proposed, and a FE model of the whole human body used for IBC simulation was developed. Secondly, the simulations of the galvanic coupling IBC with the different signal transmission paths were implemented. Finally, the feasibility of the proposed method was verified by using in vivo measurements within the frequency range of 10 kHz-5 MHz, whereby some important conclusions were deduced. Our results indicate that the proposed method will offer significant advantages in the investigation of the galvanic coupling intra-body communication.

A Finite-Element Simulation of Galvanic Coupling Intra-Body Communication Based on the Whole Human Body

PubMed Central

Song, Yong; Zhang, Kai; Hao, Qun; Hu, Lanxin; Wang, Jingwen; Shang, Fuzhou

2012-01-01

Simulation based on the finite-element (FE) method plays an important role in the investigation of intra-body communication (IBC). In this paper, a finite-element model of the whole body model used for the IBC simulation is proposed and verified, while the FE simulation of the galvanic coupling IBC with different signal transmission paths has been achieved. Firstly, a novel finite-element method for modeling the whole human body is proposed, and a FE model of the whole human body used for IBC simulation was developed. Secondly, the simulations of the galvanic coupling IBC with the different signal transmission paths were implemented. Finally, the feasibility of the proposed method was verified by using in vivo measurements within the frequency range of 10 kHz–5 MHz, whereby some important conclusions were deduced. Our results indicate that the proposed method will offer significant advantages in the investigation of the galvanic coupling intra-body communication. PMID:23202010

Characterization of elemental and structural composition of corrosion scales and deposits formed in drinking water distribution systems.

PubMed

Peng, Ching-Yu; Korshin, Gregory V; Valentine, Richard L; Hill, Andrew S; Friedman, Melinda J; Reiber, Steve H

2010-08-01

Corrosion scales and deposits formed within drinking water distribution systems (DWDSs) have the potential to retain inorganic contaminants. The objective of this study was to characterize the elemental and structural composition of extracted pipe solids and hydraulically-mobile deposits originating from representative DWDSs. Goethite (alpha-FeOOH), magnetite (Fe(3)O(4)) and siderite (FeCO(3)) were the primary crystalline phases identified in most of the selected samples. Among the major constituent elements of the deposits, iron was most prevalent followed, in the order of decreasing prevalence, by sulfur, organic carbon, calcium, inorganic carbon, phosphorus, manganese, magnesium, aluminum and zinc. The cumulative occurrence profiles of iron, sulfur, calcium and phosphorus for pipe specimens and flushed solids were similar. Comparison of relative occurrences of these elements indicates that hydraulic disturbances may have relatively less impact on the release of manganese, aluminum and zinc, but more impact on the release of organic carbon, inorganic carbon, and magnesium. (c) 2010 Elsevier Ltd. All rights reserved.

Geochemical and mineralogical composition of bog iron ore as a resource for prehistoric iron production - A case study of the Widawa catchment area in Eastern Silesia, Poland

NASA Astrophysics Data System (ADS)

Thelemann, Michael; Bebermeier, Wiebke; Hoelzmann, Philipp

2016-04-01

Spreading from the Near East in the declining Bronze Age from the 2nd millennium BCE onwards, the technique of iron smelting reached Eastern Silesia, Poland, in approximately the 2nd century BCE (pre-Roman Iron Age). At this time the region of the Widawa catchment area was inhabited by the Przeworsk culture. While the older moraine landscape of the study area lacks ores from geological rock formations, bog iron ores were relatively widespread and, due to their comparatively easy accessibility, were commonly exploited for early iron production. In this poster the mineralogical and elemental composition of local bog iron ore deposits and iron slag finds, as a by-product of the smelting process, are investigated. The crystalline mineralogical composition of local bog iron ores is dominated by quartz (SiO2) and goethite (α FeO(OH)), in contrast to slag samples in which fayalite (Fe2SiO4), wüstite (FeO) and quartz, with traces of goethite, represent the main minerals. Ores and slags are both characterized by notable hematite (Fe2O3), magnetite (Fe3O4) and maghemite (γ-Fe2O3) contents. Analyzed bog iron ore samples show iron contents of up to 64.9 mass% Fe2O3 (45.4 mass% Fe), whereas the iron contents of bloomery slags vary between 48.7 and 72.0 mass% FeO (37.9 and 56.0 mass% Fe). A principal component analysis of the element contents, which were quantified by portable energy-dispersive X-ray fluorescence spectrometry (p-ED-XRF), indicates local variations in the elemental composition. Our results show that bog iron ores are relatively widely distributed with spatially varying iron contents along the Widawa floodplain but present-day formation conditions (e.g. different ground-water levels) are negatively affected by modern land-use practices, such as agriculture and melioration measures.

High purity Fe3O4 from Local Iron Sand Extraction

NASA Astrophysics Data System (ADS)

Gunanto, Y. E.; Izaak, M. P.; Jobiliong, E.; Cahyadi, L.; Adi, W. A.

2018-04-01

Indonesia has a long coastline and is rich with iron sand. The iron sand is generally rich in various elements such as iron and titanium. One of the products processing of the iron sand mineral is iron (II) (III) oxide (magnetite Fe3O4). The stages of purification process to extracting magnetite phase and discarding the other phases has been performed. Magnetite phase analysis of ironsand extraction retrieved from Indonesia have been investigated. The result of analysis element of iron sand shows that it consists of majority Fe around 65 wt%. However, there are still 17 impurities such as Ti, Al, Ce, Co, Cr, Eu, La, Mg, Mn, Na, Sc, Sm, Th, V, Yb, and Zn. After extraction process, Fe element content increases up to 94%. The iron sand powder after milling for 10 hours and separating using a magnetic separator, the iron sand powders are dissolved in acid chloride solution to form a solution of iron chloride, and this solution is sprinkled with sodium hydroxide to obtain fine powders of Fe3O4. The fine powders which formed were washed with de-mineralization water. The X-ray diffraction pattern shows that the fine powders have a single phase of Fe3O4. The analysis result shows that the sample has the chemical formula: Fe3O4 with a cubic crystal system, space group: Fd-3m and lattice parameters: a = b = c = 8.3681 (1) Å, α = β = γ = 90°. The microstructure analysis shows that the particle of Fe3O4 homogeneously shaped like spherical. The magnetic properties using vibrating sample magnetometer shows that Fe3O4 obtained have ferromagnetic behavior with soft magnetic characteristics. We concluded that this purification of iron sand had been successfully performed to obtain fine powders of Fe3O4 with high purity.

Toxic trace element assessment for soils/sediments deposited during Hurricanes Katrina and Rita from southern Louisiana, USA: a sequential extraction analysis.

PubMed

Shi, Honglan; Witt, Emitt C; Shu, Shi; Su, Tingzhi; Wang, Jianmin; Adams, Craig

2010-07-01

Analysis of soil/sediment samples collected in the southern Louisiana, USA, region three weeks after Hurricanes Katrina and Rita passed was performed using sequential extraction procedures to determine the origin, mode of occurrence, biological availability, mobilization, and transport of trace elements in the environment. Five fractions: exchangeable, bound to carbonates, bound to iron (Fe)-manganese (Mn) oxides, bound to organic matter, and residual, were subsequently extracted. The toxic trace elements Pb, As, V, Cr, Cu, and Cd were analyzed in each fraction, together with Fe in 51 soil/sediment samples. Results indicated that Pb and As were at relatively high concentrations in many of the soil/sediment samples. Because the forms in which Pb and As are present tend to be highly mobile under naturally occurring environmental conditions, these two compounds pose an increased health concern.Vanadium and Cr were mostly associated with the crystal line nonmobile residual fraction. A large portion of the Cu was associated with organic matter and residual fraction. Cadmium concentrations were low in all soil/sediment samples analyzed and most of this element tended to be associated with the mobile fractions. An average of 21% of the Fe was found in the Fe-Mn oxide fraction, indicating that a substantial part of the Fe was in an oxidized form. The significance of the overall finding of the present study indicated that the high concentrations and high availabilities of the potentially toxic trace elements As and Pb may impact the environment and human health in southern Louisiana and, in particular, the New Orleans area. Copyright (c) 2010 SETAC.

Heavy-Element Abundances in Solar Energetic Particle Events

NASA Technical Reports Server (NTRS)

Reames, Donald V.

2004-01-01

We survey the relative abundances of elements with 1 less than or = Z less than or = 82 in solar energetic particle (SEP) events observed at 2 - 10 MeV amu" during nearly 9 years aboard the Wind spacecraft, with special emphasis on enhanced abundances of elements with 2Z greater than or = 34. Abundances of Fe/O again show a bimodal distribution with distinct contributions from impulsive and gradual SEP events as seen in earlier solar cycles. Periods with greatly enhanced abundances of (50 less than or = Z less than or = 56)/O, like those with enhanced He-3/He-4, fall prominently in the Fe-rich population of the impulsive SEP events. In a sample of the 39 largest impulsive events, 25 have measurable enhancements in (50 less than or = Z less than or = 56)/O and (76 less than or = Z less than or = 82)/O, relative to coronal values, ranging from approx. 100 to 10,000. By contrast, in a sample of 45 large gradual events the corresponding enhancements vary from approx. 0.2 to 20. However, the magnitude of the heavy-element enhancements in impulsive events is less striking than their strong correlation with the Fe spectral index and flare size, with the largest enhancements occurring in flares with the steepest Fe spectra, the smallest Fe fluence, and the lowest X-ray intensity, as reported here for the first time Thus it seem that small events with low energy input can produce only steep spectra of the dominant species but accelerate rare heavy elements with great efficiency, probably by selective absorption of resonant waves in the flare plasma. With increased energy input, enhancements diminish, as heavy ions are depleted, and spectra of the dominant species harden.

Heavy-Element Abundances in Solar Energetic Particle Events

NASA Technical Reports Server (NTRS)

Reames, D. V.; Ng, C. K.

2004-01-01

We survey the relative abundances of elements with 1 < or equal to Z < or equal to 82 in solar energetic particle (SEP) events observed at 2-10 MeV/amu during nearly 9 years aboard the Wind spacecraft, with special emphasis on enhanced abundances of elements with Z > or equal to 34. Abundances of Fe/O again show a bimodal distribution with distinct contributions from impulsive and gradual SEP events as seen in earlier solar cycles. Periods with greatly enhanced abundances of (50 < or equal to Z < or equal to 56)/O, like those with enhanced (3)He/(4)He, fall prominently in the Fe-rich population of the impulsive SEP events. In a sample of the 39 largest impulsive events, 25 have measurable enhancements in (50 < or equal to z < or equal to 56)/O and (76 < or equal to Z < or equal to 82)/O, relative to coronal values, ranging from approx. 100 to 10,000. By contrast, in a sample of 45 large gradual events the corresponding enhancements vary from approx. 0.2 to 20. However, the magnitude of the heavy-element enhancements in impulsive events is less striking than their strong correlation with the Fe spectral index and flare size, with the largest enhancements occurring in flares with the steepest Fe spectra, the smallest Fe fluence, and the lowest X-ray intensity, as reported here for the first time. Thus it seems that small events with low energy input can produce only steep spectra of the dominant species but accelerate rare heavy elements with great efficiency, probably by selective absorption of resonant waves in the flare plasma. With increased energy input, enhancements diminish, as heavy ions are depleted, and spectra of the dominant species harden.

Efficient finite element modelling for the investigation of the dynamic behaviour of a structure with bolted joints

NASA Astrophysics Data System (ADS)

Omar, R.; Rani, M. N. Abdul; Yunus, M. A.; Mirza, W. I. I. Wan Iskandar; Zin, M. S. Mohd

2018-04-01

A simple structure with bolted joints consists of the structural components, bolts and nuts. There are several methods to model the structures with bolted joints, however there is no reliable, efficient and economic modelling methods that can accurately predict its dynamics behaviour. Explained in this paper is an investigation that was conducted to obtain an appropriate modelling method for bolted joints. This was carried out by evaluating four different finite element (FE) models of the assembled plates and bolts namely the solid plates-bolts model, plates without bolt model, hybrid plates-bolts model and simplified plates-bolts model. FE modal analysis was conducted for all four initial FE models of the bolted joints. Results of the FE modal analysis were compared with the experimental modal analysis (EMA) results. EMA was performed to extract the natural frequencies and mode shapes of the test physical structure with bolted joints. Evaluation was made by comparing the number of nodes, number of elements, elapsed computer processing unit (CPU) time, and the total percentage of errors of each initial FE model when compared with EMA result. The evaluation showed that the simplified plates-bolts model could most accurately predict the dynamic behaviour of the structure with bolted joints. This study proved that the reliable, efficient and economic modelling of bolted joints, mainly the representation of the bolting, has played a crucial element in ensuring the accuracy of the dynamic behaviour prediction.

Quantifying Spatial Variability of Selected Soil Trace Elements and Their Scaling Relationships Using Multifractal Techniques

PubMed Central

Zhang, Fasheng; Yin, Guanghua; Wang, Zhenying; McLaughlin, Neil; Geng, Xiaoyuan; Liu, Zuoxin

2013-01-01

Multifractal techniques were utilized to quantify the spatial variability of selected soil trace elements and their scaling relationships in a 10.24-ha agricultural field in northeast China. 1024 soil samples were collected from the field and available Fe, Mn, Cu and Zn were measured in each sample. Descriptive results showed that Mn deficiencies were widespread throughout the field while Fe and Zn deficiencies tended to occur in patches. By estimating single multifractal spectra, we found that available Fe, Cu and Zn in the study soils exhibited high spatial variability and the existence of anomalies ([α(q)max−α(q)min]≥0.54), whereas available Mn had a relatively uniform distribution ([α(q)max−α(q)min]≈0.10). The joint multifractal spectra revealed that the strong positive relationships (r≥0.86, P<0.001) among available Fe, Cu and Zn were all valid across a wider range of scales and over the full range of data values, whereas available Mn was weakly related to available Fe and Zn (r≥0.18, P<0.01) but not related to available Cu (r = −0.03, P = 0.40). These results show that the variability and singularities of selected soil trace elements as well as their scaling relationships can be characterized by single and joint multifractal parameters. The findings presented in this study could be extended to predict selected soil trace elements at larger regional scales with the aid of geographic information systems. PMID:23874944

Damage buildup and edge dislocation mobility in equiatomic multicomponent alloys

NASA Astrophysics Data System (ADS)

Granberg, F.; Djurabekova, F.; Levo, E.; Nordlund, K.

2017-02-01

A new class of single phase metal alloys of equal atomic concentrations has shown very promising mechanical properties and good corrosion resistance. Moreover, a significant reduction in damage accumulation during prolonged irradiation has also been observed in these equiatomic multicomponent alloys. A comparison of elemental Ni with the two component NiFe- and the three component NiCoCr-alloy showed a substantial reduction in damage in both alloys, and an even larger difference was seen if only larger clusters were considered. One of the factors limiting the damage build-up in the alloys compared to the elemental material was seen to be dislocation mobility (Granberg et al., 2016). In this Article, we focus on a more thorough investigation of the mobility of edge dislocations in different cases of the Ni-, NiFe- and NiCoCr-samples. We find that even though the saturated amount of defects in the alloys is lower than in elemental Ni, the defect buildup in the early stages is faster in the alloys. We also find that the dislocation mobility in NiFe is lower than in Ni, at low stresses, and that the onset stress in NiFe is higher than in Ni. The same phenomenon was seen in comparison between NiFe and NiCoCr, since the three component alloy had lower dislocation mobility and higher onset stress. The dislocation velocity in elemental Ni plateaued out just under the forbidden velocity, whereas the alloys showed a more complex behaviour.

Supernova Ejecta in the Youngest Galactic Supernova Remnant G1.9+0.3

NASA Technical Reports Server (NTRS)

Borkowski, Kazimierz J.; Reynolds, Stephen P.; Hwang, Una; Green, David A.; Petre, Robert; Krishnamurthy, Kalyani; Willett, Rebecca

2013-01-01

G1.9+0.3 is the youngest known Galactic supernova remnant (SNR), with an estimated supernova (SN) explosion date of approximately 1900, and most likely located near the Galactic Center. Only the outermost ejecta layers with free-expansion velocities (is) approximately greater than 18,000 km s-1 have been shocked so far in this dynamically young, likely Type Ia SNR. A long (980 ks) Chandra observation in 2011 allowed spatially-resolved spectroscopy of heavy-element ejecta. We denoised Chandra data with the spatio-spectral method of Krishnamurthy et al., and used a wavelet based technique to spatially localize thermal emission produced by intermediate-mass elements (IMEs: Si and S) and iron. The spatial distribution of both IMEs and Fe is extremely asymmetric, with the strongest ejecta emission in the northern rim. Fe K alpha emission is particularly prominent there, and fits with thermal models indicate strongly oversolar Fe abundances. In a localized, outlying region in the northern rim, IMEs are less abundant than Fe, indicating that undiluted Fe-group elements (including 56Ni) with velocities greater than 18,000 km s-1 were ejected by this SN. But in the inner west rim, we find Si- and S-rich ejecta without any traces of Fe, so high-velocity products of O-burning were also ejected. G1.9+0.3 appears similar to energetic Type Ia SNe such as SN 2010jn where iron-group elements at such high free-expansion velocities have been recently detected. The pronounced asymmetry in the ejecta distribution and abundance inhomogeneities are best explained by a strongly asymmetric SN explosion, similar to those produced in some recent 3D delayed-detonation Type Ia models.

AN ELEMENTAL ASSAY OF VERY, EXTREMELY, AND ULTRA-METAL-POOR STARS

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

Hansen, T.; Christlieb, N.; Hansen, C. J.

2015-07-10

We present a high-resolution elemental-abundance analysis for a sample of 23 very metal-poor ([Fe/H] < −2.0) stars, 12 of which are extremely metal-poor ([Fe/H] < −3.0), and 4 of which are ultra-metal-poor ([Fe/H] < −4.0). These stars were targeted to explore differences in the abundance ratios for elements that constrain the possible astrophysical sites of element production, including Li, C, N, O, the α-elements, the iron-peak elements, and a number of neutron-capture elements. This sample substantially increases the number of known carbon-enhanced metal-poor (CEMP) and nitrogen-enhanced metal-poor (NEMP) stars—our program stars include eight that are considered “normal” metal-poor stars, sixmore » CEMP-no stars, five CEMP-s stars, two CEMP-r stars, and two CEMP-r/s stars. One of the CEMP-r stars and one of the CEMP-r/s stars are possible NEMP stars. We detect lithium for three of the six CEMP-no stars, all of which are Li depleted with respect to the Spite plateau. The majority of the CEMP stars have [C/N] > 0. The stars with [C/N] < 0 suggest a larger degree of mixing; the few CEMP-no stars that exhibit this signature are only found at [Fe/H] < −3.4, a metallicity below which we also find the CEMP-no stars with large enhancements in Na, Mg, and Al. We confirm the existence of two plateaus in the absolute carbon abundances of CEMP stars, as suggested by Spite et al. We also present evidence for a “floor” in the absolute Ba abundances of CEMP-no stars at A(Ba) ∼ −2.0.« less

Heavy Element Abundances in Two B0-B0.5 Main Sequence Stars in the Small Magellanic Cloud

NASA Astrophysics Data System (ADS)

Peters, Geraldine J.

We propose FUSE observations of AV304 (B0.5V) and NGC346-637 B0V), two sharp-lined main-sequence stars in the Small Magellanic Cloud, to determine the abundances of heavy elements, especially those of the iron group. The FUSE spectral region contains numerous Fe III lines, including the resonance multiplet (UV 1) near 1130 Angstroms, that is excellent for abundance determinations and two strong multiplets of V III, an ion that does not produce measurable lines longward of 1200 Angstoms, in metal-deficient stars. In addition there are several measurable lines from Cr III and Mn III. A limited analyses of ground-based spectra of these stars by Dufton et al. (1990) and Rolleston et al. (1993) indicated an average underabundance of 0.7-0.8 dex for most light elements and a recent analysis of HSTSTIS data on AV304 by Peters & Grigsby (2001) suggests that the Fe group elements are depleted by the same amount relative to the sun. When combined with the HST-STIS results, this effort will represent the first attempt to measure the abundances of Fe group elements in the photospheres of early B, main sequence stars in an external galaxy. Although abundances of the Fe-peak elements are of interest because they are important for assessing opacities for stellar evolution calculations and the validity of theoretical calculations of explosive nucleosynthesis, the ground-based study did not yield this information because measurable lines from these species are found only in the UV spectral region. Abundances and abundance ratios of both heavy & light elements will be compared with the HST-STIS results from AV304, H II regions, supernova remnants, evolved massive stars in the SMC, and theoretical calculations of nucleosynthesis.

Southern Ocean biological iron cycling in the pre-whaling and present ecosystems.

PubMed

Maldonado, Maria T; Surma, Szymon; Pakhomov, Evgeny A

2016-11-28

This study aimed to create the first model of biological iron (Fe) cycling in the Southern Ocean food web. Two biomass mass-balanced Ecopath models were built to represent pre- and post-whaling ecosystem states (1900 and 2008). Functional group biomasses (tonnes wet weight km -2 ) were converted to biogenic Fe pools (kg Fe km -2 ) using published Fe content ranges. In both models, biogenic Fe pools and consumption in the pelagic Southern Ocean were highest for plankton and small nektonic groups. The production of plankton biomass, particularly unicellular groups, accounted for the highest annual Fe demand. Microzooplankton contributed most to biological Fe recycling, followed by carnivorous zooplankton and krill. Biological Fe recycling matched previous estimates, and, under most conditions, could entirely meet the Fe demand of bacterioplankton and phytoplankton. Iron recycling by large baleen whales was reduced 10-fold by whaling between 1900 and 2008. However, even under the 1900 scenario, the contribution of whales to biological Fe recycling was negligible compared with that of planktonic consumers. These models are a first step in examining oceanic-scale biological Fe cycling, highlighting gaps in our present knowledge and key questions for future research on the role of marine food webs in the cycling of trace elements in the sea.This article is part of the themed issue 'Biological and climatic impacts of ocean trace element chemistry'. © 2016 The Author(s).

Methodologies for validating ray-based forward model using finite element method in ultrasonic array data simulation

NASA Astrophysics Data System (ADS)

Zhang, Jie; Nixon, Andrew; Barber, Tom; Budyn, Nicolas; Bevan, Rhodri; Croxford, Anthony; Wilcox, Paul

2018-04-01

In this paper, a methodology of using finite element (FE) model to validate a ray-based model in the simulation of full matrix capture (FMC) ultrasonic array data set is proposed. The overall aim is to separate signal contributions from different interactions in FE results for easier comparing each individual component in the ray-based model results. This is achieved by combining the results from multiple FE models of the system of interest that include progressively more geometrical features while preserving the same mesh structure. It is shown that the proposed techniques allow the interactions from a large number of different ray-paths to be isolated in FE results and compared directly to the results from a ray-based forward model.

Coding "We-ness" in couple's relationship stories: A method for assessing mutuality in couple therapy.

PubMed

Gildersleeve, Sara; Singer, Jefferson A; Skerrett, Karen; Wein, Shelter

2017-05-01

"We-ness," a couple's mutual investment in their relationship and in each other, has been found to be a potent dimension of couple resilience. This study examined the development of a method to capture We-ness in psychotherapy through the coding of relationship narratives co-constructed by couples ("We-Stories"). It used a coding system to identify the core thematic elements that make up these narratives. Couples that self-identified as "happy" (N = 53) generated We-Stories and completed measures of relationship satisfaction and mutuality. These stories were then coded using the We-Stories coding manual. Findings indicated that security, an element that involves aspects of safety, support, and commitment, was most common, appearing in 58.5% of all narratives. This element was followed by the elements of pleasure (49.1%) and shared meaning/vision (37.7%). The number of "We-ness" elements was also correlated with and predictive of discrepancy scores on measures of relationship mutuality, indicating the validity of the We-Stories coding manual. Limitations and future directions are discussed.

Imitation Learning Errors Are Affected by Visual Cues in Both Performance and Observation Phases.

PubMed

Mizuguchi, Takashi; Sugimura, Ryoko; Shimada, Hideaki; Hasegawa, Takehiro

2017-08-01

Mechanisms of action imitation were examined. Previous studies have suggested that success or failure of imitation is determined at the point of observing an action. In other words, cognitive processing after observation is not related to the success of imitation; 20 university students participated in each of three experiments in which they observed a series of object manipulations consisting of four elements (hands, tools, object, and end points) and then imitated the manipulations. In Experiment 1, a specific intially observed element was color coded, and the specific manipulated object at the imitation stage was identically color coded; participants accurately imitated the color coded element. In Experiment 2, a specific element was color coded at the observation but not at the imitation stage, and there were no effects of color coding on imitation. In Experiment 3, participants were verbally instructed to attend to a specific element at the imitation stage, but the verbal instructions had no effect. Thus, the success of imitation may not be determined at the stage of observing an action and color coding can provide a clue for imitation at the imitation stage.

Characterization of Three Carbon- and Nitrogen-Rich Particles from Comet 81P/WILD

NASA Technical Reports Server (NTRS)

Gallien, J.-P.; Khodja, H.; Herzog, G. F.; Taylor, S.; Koepsell, E.; Daghlian, C. P.; Flynn, G. J.; Sitnitsky, I.; Lanzirotti, A.; Sutton, S. R.;

HD 179821 (V1427 Aql, IRAS 19114+0002) - a massive post-red supergiant star?

NASA Astrophysics Data System (ADS)

Şahin, T.; Lambert, David L.; Klochkova, Valentina G.; Panchuk, Vladimir E.

2016-10-01

We have derived elemental abundances of a remarkable star, HD 179821, with unusual composition (e.g. [Na/Fe] = 1.0 ± 0.2 dex) and extra-ordinary spectral characteristics. Its metallicity at [Fe/H] = 0.4 dex places it among the most metal-rich stars yet analysed. The abundance analysis of this luminous star is based on high-resolution and high-quality (S/N ≈ 120-420) optical echelle spectra from McDonald Observatory and Special Astronomy Observatory. The data includes five years of observations over 21 epochs. Standard 1D local thermodynamic equilibrium analysis provides a fresh determination of the atmospheric parameters over all epochs: Teff = 7350 ± 200 K, log g= +0.6 ± 0.3, and a microturbulent velocity ξ = 6.6 ± 1.6 km s-1 and [Fe/H] = 0.4 ± 0.2, and a carbon abundance [C/Fe] = -0.19 ± 0.30. We find oxygen abundance [O/Fe] = -0.25 ± 0.28 and an enhancement of 0.9 dex in N. A supersonic macroturbulent velocity of 22.0 ± 2.0 km s-1 is determined from both strong and weak Fe I and Fe II lines. Elemental abundances are obtained for 22 elements. HD 179821 is not enriched in s-process products. Eu is overabundant relative to the anticipated [X/Fe] ≈ 0.0. Some peculiarities of its optical spectrum (e.g. variability in the spectral line shapes) is noticed. This includes the line profile variations for H α line. Based on its estimated luminosity, effective temperature and surface gravity, HD 179821 is a massive star evolving to become a red supergiant and finally a Type II supernova.

Discrimination of Venezuelan spirituous beverages by a trace element-radial basis neural network approach.

PubMed

Hernández-Caraballo, Edwin A; Avila de Hernández, Rita M; Rivas-Echeverría, Francklin; Capote-Luna, Tarcisio

2008-01-15

Radial basis neural networks (RBNNs) were developed and evaluated for discrimination of specimens of 'aguardiente de Cocuy', a spirituous beverage produced in the northwestern region of Venezuela. The beverage is distilled from the must of Agave cocui Trelease in an artisanship fashion with little quality control. Forty specimens, with known concentrations of copper, iron, and zinc, were used in this study. The specimens were previously collected in various locations around Sucre Municipality (Falcón State) and Urdaneta Municipality (Lara State). The normalized concentrations of these elements served as indirect descriptors of origin (input data). They were presented to the neural networks through 1-3 input nodes in seven different combinations. In addition, two categories (two collection sites) and four categories (two collection sites+two manufacturing conditions) were designated as output data, in order to assess the impact of such selection on the discrimination performance. The overall performance of the four-category RBNNs was as follows (the input data is indicated in parentheses): (Cu-Fe)>(Cu-Zn)>(Cu)>(Zn)>(Fe-Zn)>(Cu-Fe-Zn)>(Fe). In this case, the highest percentage of correct hits was 82.5%. For the two-category RBNNs, the performance decreased as indicated below: (Cu)>(Cu-Fe)>(Cu-Zn)>(Fe-Zn)>(Zn) approximately (Cu-Fe-Zn)>(Fe). The reduction in the number of categories led to an increase in the discrimination performance of all the RBNNs, the best of which was 90.0%. The possibility of discriminating specimens of 'aguardiente de Cocuy' with such an accuracy, based on a single-element determination, is particularly attractive as it would result in a reduction of analysis' costs and laboratory's response time.

BISON Fuel Performance Analysis of FeCrAl cladding with updated properties

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

Sweet, Ryan; George, Nathan M.; Terrani, Kurt A.

2016-08-30

In order to improve the accident tolerance of light water reactor (LWR) fuel, alternative cladding materials have been proposed to replace zirconium (Zr)-based alloys. Of these materials, there is a particular focus on iron-chromium-aluminum (FeCrAl) alloys due to much slower oxidation kinetics in high-temperature steam than Zr-alloys. This should decrease the energy release due to oxidation and allow the cladding to remain integral longer in the presence of high temperature steam, making accident mitigation more likely. As a continuation of the development for these alloys, suitability for normal operation must also be demonstrated. This research is focused on modeling themore » integral thermo-mechanical performance of FeCrAl-cladded fuel during normal reactor operation. Preliminary analysis has been performed to assess FeCrAl alloys (namely Alkrothal 720 and APMT) as a suitable fuel cladding replacement for Zr-alloys, using the MOOSE-based, finite-element fuel performance code BISON and the best available thermal-mechanical and irradiation-induced constitutive properties. These simulations identify the effects of the mechanical-stress and irradiation response of FeCrAl, and provide a comparison with Zr-alloys. In comparing these clad materials, fuel rods have been simulated for normal reactor operation and simple steady-state operation. Normal reactor operating conditions target the cladding performance over the rod lifetime (~4 cycles) for the highest-power rod in the highest-power fuel assembly under reactor power maneuvering. The power histories and axial temperature profiles input into BISON were generated from a neutronics study on full-core reactivity equivalence for FeCrAl using the 3D full core simulator NESTLE. Evolution of the FeCrAl cladding behavior over time is evaluated by using steady-state operating conditions such as a simple axial power profile, a constant cladding surface temperature, and a constant fuel power history. The fuel rod designs and operating conditions used are based off the Peach Bottom BWR and design consideration was given to minimize the neutronic penalty of the FeCrAl cladding by changing fuel enrichment and cladding thickness. As this study progressed, systematic parametric analysis of the fuel and cladding creep responses were also performed.« less

CELFE/NASTRAN Code for the Analysis of Structures Subjected to High Velocity Impact

NASA Technical Reports Server (NTRS)

Chamis, C. C.

1978-01-01

CELFE (Coupled Eulerian Lagrangian Finite Element)/NASTRAN Code three-dimensional finite element code has the capability for analyzing of structures subjected to high velocity impact. The local response is predicted by CELFE and, for large problems, the far-field impact response is predicted by NASTRAN. The coupling of the CELFE code with NASTRAN (CELFE/NASTRAN code) and the application of the code to selected three-dimensional high velocity impact problems are described.

Simultaneous biosorption of selenium, arsenic and molybdenum with modified algal-based biochars.

PubMed

Johansson, Charlotte L; Paul, Nicholas A; de Nys, Rocky; Roberts, David A

2016-01-01

Ash disposal waters from coal-fired power stations present a challenging water treatment scenario as they contain high concentrations of the oxyanions Se, As and Mo which are difficult to remove through conventional techniques. In an innovative process, macroalgae can be treated with Fe and processed through slow pyrolysis into Fe-biochar which has a high affinity for oxyanions. However, the effect of production conditions on the efficacy of Fe-biochar is poorly understood. We produced Fe-biochar from two algal sources; "Gracilaria waste" (organic remnants after agar is extracted from cultivated Gracilaria) and the freshwater macroalgae Oedogonium. Pyrolysis experiments tested the effects of the concentration of Fe(3+) in pre-treatment, and pyrolysis temperatures, on the efficacy of the Fe-biochar. The efficacy of Fe-biochar increased with increasing concentrations of Fe(3+) in the pre-treatment solutions, and decreased with increasing pyrolysis temperatures. The optimized Fe-biochar for each biomass was produced by treatment with a 12.5% w/v Fe(3+) solution, followed by slow pyrolysis at 300 °C. The Fe-biochar produced in this way had higher a biosorption capacity for As and Mo (62.5-80.7 and 67.4-78.5 mg g(-1) respectively) than Se (14.9-38.8 mg g(-1)) in single-element mock effluents, and the Fe-biochar produced from Oedogonium had a higher capacity for all elements than the Fe-biochar produced from Gracilaria waste. Regardless, the optimal Fe-biochars from both biomass sources were able to effectively treat Se, As and Mo simultaneously in an ash disposal effluent from a power station. The production of Fe-biochar from macroalgae is a promising technique for treatment of complex effluents containing oxyanions. Copyright © 2015 Elsevier Ltd. All rights reserved.

Total-diet study: dietary intakes of macro elements and trace elements in Italy.

PubMed

Lombardi-Boccia, Ginevra; Aguzzi, Altero; Cappelloni, Marsilio; Di Lullo, Giuseppe; Lucarini, Massimo

2003-12-01

The present study provides the dietary intakes of macro elements (Ca, Mg, Na, K, P) and trace elements (Fe, Zn, Cu, Se) from the Italian total diet. The contribution of the most representative food groups of the total diet (cereals and cereal products, vegetables, fruit, milk and dairy products, meat and meat products, fish) to the daily intakes of these nutrients was also evaluated. The Italian total diet was formulated following the 'market-basket' approach. Cereals represented the primary sources of Cu (35 %), Fe (30 %) and Mg (27 %). About 89 % of the total daily intake of Fe was derived from plant foods. The vegetables food group was the main source of dietary K (27 %). Most of the Ca (59 %) and P (27 %) was derived from the milk-and-dairy food group. Of the dietary Zn, 41 % was provided by meat, which, together with the fish food group, was the primary source of Se (20 %). The adequacy of the Italian total diet with respect to nutritional elements was assessed by comparing the daily intakes with the average requirement values of the Italian recommended dietary allowances. The present findings indicated that the dietary patterns of the Italian total diet were generally consistent with current Italian dietary recommendations for both macro and trace elements. The major concern was for Ca, for which daily intake was 76 % of the average recommendation for the Italian population. It should not be ruled out that there could be a potential risk of inadequate Fe intake in some segments of the population.

Multigrid finite element method in stress analysis of three-dimensional elastic bodies of heterogeneous structure

NASA Astrophysics Data System (ADS)

Matveev, A. D.

2016-11-01

To calculate the three-dimensional elastic body of heterogeneous structure under static loading, a method of multigrid finite element is provided, when implemented on the basis of algorithms of finite element method (FEM), using homogeneous and composite threedimensional multigrid finite elements (MFE). Peculiarities and differences of MFE from the currently available finite elements (FE) are to develop composite MFE (without increasing their dimensions), arbitrarily small basic partition of composite solids consisting of single-grid homogeneous FE of the first order can be used, i.e. in fact, to use micro approach in finite element form. These small partitions allow one to take into account in MFE, i.e. in the basic discrete models of composite solids, complex heterogeneous and microscopically inhomogeneous structure, shape, the complex nature of the loading and fixation and describe arbitrarily closely the stress and stain state by the equations of three-dimensional elastic theory without any additional simplifying hypotheses. When building the m grid FE, m of nested grids is used. The fine grid is generated by a basic partition of MFE, the other m —1 large grids are applied to reduce MFE dimensionality, when m is increased, MFE dimensionality becomes smaller. The procedures of developing MFE of rectangular parallelepiped, irregular shape, plate and beam types are given. MFE generate the small dimensional discrete models and numerical solutions with a high accuracy. An example of calculating the laminated plate, using three-dimensional 3-grid FE and the reference discrete model is given, with that having 2.2 milliards of FEM nodal unknowns.

Dissolved and colloidal trace elements in the Mississippi River Delta outflow after Hurricanes Katrina and Rita

USGS Publications Warehouse

Shim, Moo-Joon; Swarzenski, Peter W.; Shiller, Alan M.

2012-01-01

The Mississippi River delta outflow region is periodically disturbed by tropical weather systems including major hurricanes, which can terminate seasonal bottom water hypoxia and cause the resuspension of shelf bottom sediments which could result in the injection of trace elements into the water column. In the summer of 2005, Hurricanes Katrina and Rita passed over the Louisiana Shelf within a month of each other. Three weeks after Rita, we collected water samples in the Mississippi River delta outflow, examining the distributions of trace elements to study the effect of Hurricanes Katrina and Rita. We observed limited stratification on the shelf and bottom waters that were no longer hypoxic. This resulted, for instance, in bottom water dissolved Mn being lower than is typically observed during hypoxia, but with concentrations still compatible with Mn–O2 trends previously reported. Interestingly, for no element were we able to identify an obvious effect of sediment resuspension on its distribution. In general, elemental distributions were compatible with previous observations in the Mississippi outflow system. Co and Re, which have not been reported for this system previously, showed behavior consistent with other systems: input for Co likely from desorption and conservative mixing for Re. For Cs, an element for which there is little information regarding its estuarine behavior, conservative mixing was also observed. Our filtration method, which allowed us to distinguish the dissolved (<0.02 μm) from colloidal (0.02–0.45 μm) phase, revealed significant colloidal fractions for Fe and Zn, only. For Fe, the colloidal phase was the dominant fraction and was rapidly removed at low salinity. Dissolved Fe, in contrast, persisted out to mid-salinities, being removed in a similar fashion to nitrate. This ability to distinguish the smaller Fe (likely dominantly organically complexed) from larger colloidal suspensates may be useful in better interpreting the bioavailablity of the Fe in estuarine systems.

The effects of copper, manganese and zinc on plant growth and elemental accumulation in the manganese-hyperaccumulator Phytolacca americana.

PubMed

Zhao, Huijun; Wu, Liangqi; Chai, Tuanyao; Zhang, Yuxiu; Tan, Jinjuan; Ma, Shengwen

2012-09-01

Synchrotron radiation X-ray fluorescence (SRXRF) and inductively coupled plasma mass spectrometry were used to estimate major, minor and trace elements in Cu-, Zn- and Mn-treated Phytolacca americana. The effects of the addition of Cu, Zn and Mn on morphological parameters, such as root length, shoot height, and fresh and dry weights of shoots and roots, were also examined. In addition, the activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), guaiacol peroxidases (GPX) and catalase (CAT) and the expression of Fe-SOD, Cu/Zn-SOD, metallothionein-2 and glutathione S-transferase (GST) exposed to the highest amounts of Cu, Zn or Mn were detected. Our results confirmed the following: (1) Zn supplementation leads to chlorosis, disturbed elemental homeostasis and decreased concentrations of micro- and macroelements such as Fe, Mg, Mn, Ca and K. Cu competed with Fe, Mn and Zn uptake in plants supplemented with 25 μM Cu. However, no antagonistic interactions took place between Cu, Zn, Mn and Fe uptake in plants supplemented with 100 μM Cu. Mn supplementation at various concentrations had no negative effects on elemental deficits. Mn was co-located with high concentrations of Fe and Zn in mature leaves and the concentrations of macro elements were unchanged. (2) P. americana supplemented with increased concentrations of Zn and Cu exhibited lower biomass production and reduced plant growth. (3) When plants were supplemented with the highest Zn and Cu concentrations, symptoms of toxicity corresponded to decreased SOD or CAT activities and increased APX and GPX activities. However, Mn tolerance corresponded to increased SOD and CAT activities and decreased POD and APX activities. Our study revealed that heavy metals partially exert toxicity by disturbing the nutrient balance and modifying enzyme activities that induce damage in plants. However, P. americana has evolved hyper accumulating mechanisms to maintain elemental balance and redox homeostasis under excess Mn. Copyright © 2012 Elsevier GmbH. All rights reserved.

Dissolved and colloidal trace elements in the Mississippi River delta outflow after Hurricanes Katrina and Rita

NASA Astrophysics Data System (ADS)

Shim, Moo-Joon; Swarzenski, Peter W.; Shiller, Alan M.

2012-07-01

The Mississippi River delta outflow region is periodically disturbed by tropical weather systems including major hurricanes, which can terminate seasonal bottom water hypoxia and cause the resuspension of shelf bottom sediments which could result in the injection of trace elements into the water column. In the summer of 2005, Hurricanes Katrina and Rita passed over the Louisiana Shelf within a month of each other. Three weeks after Rita, we collected water samples in the Mississippi River delta outflow, examining the distributions of trace elements to study the effect of Hurricanes Katrina and Rita. We observed limited stratification on the shelf and bottom waters that were no longer hypoxic. This resulted, for instance, in bottom water dissolved Mn being lower than is typically observed during hypoxia, but with concentrations still compatible with Mn-O2 trends previously reported. Interestingly, for no element were we able to identify an obvious effect of sediment resuspension on its distribution. In general, elemental distributions were compatible with previous observations in the Mississippi outflow system. Co and Re, which have not been reported for this system previously, showed behavior consistent with other systems: input for Co likely from desorption and conservative mixing for Re. For Cs, an element for which there is little information regarding its estuarine behavior, conservative mixing was also observed. Our filtration method, which allowed us to distinguish the dissolved (<0.02 μm) from colloidal (0.02-0.45 μm) phase, revealed significant colloidal fractions for Fe and Zn, only. For Fe, the colloidal phase was the dominant fraction and was rapidly removed at low salinity. Dissolved Fe, in contrast, persisted out to mid-salinities, being removed in a similar fashion to nitrate. This ability to distinguish the smaller Fe (likely dominantly organically complexed) from larger colloidal suspensates may be useful in better interpreting the bioavailablity of the Fe in estuarine systems.

INAA Application for Trace Element Determination in Biological Reference Material

NASA Astrophysics Data System (ADS)

Atmodjo, D. P. D.; Kurniawati, S.; Lestiani, D. D.; Adventini, N.

2017-06-01

Trace element determination in biological samples is often used in the study of health and toxicology. Determination change to its essentiality and toxicity of trace element require an accurate determination method, which implies that a good Quality Control (QC) procedure should be performed. In this study, QC for trace element determination in biological samples was applied by analyzing the Standard Reference Material (SRM) Bovine muscle 8414 NIST using Instrumental Neutron Activation Analysis (INAA). Three selected trace element such as Fe, Zn, and Se were determined. Accuracy of the elements showed as %recovery and precision as %coefficient of variance (%CV). The result showed that %recovery of Fe, Zn, and Se were in the range between 99.4-107%, 92.7-103%, and 91.9-112%, respectively, whereas %CV were 2.92, 3.70, and 5.37%, respectively. These results showed that INAA method is precise and accurate for trace element determination in biological matrices.

Evaluation of Trace Elements and Their Relationship with Growth and Development of Young Children.

PubMed

Cao, Jia; Gao, Zhenyan; Yan, Jin; Li, Minming; Su, Jia; Xu, Jian; Yan, Chong-Huai

2016-06-01

This study was conducted to assess the levels of trace elements and their relationship with growth and development of children in Shanghai, China, to offer scientific evidence for supplementing trace elements in children. A stratified, clustered, random sampling method was used in the study. Blood samples were taken from 2141 Shanghai children from 0 to 6.0 years old, and the concentrations of zinc (Zn), calcium (Ca), iron (Fe), copper (Cu), and magnesium (Mg) were measured using inductively coupled plasma mass spectrometry (ICP-MS). Nutritional status was determined and Z-scores of anthropometric parameters, such as height for age (HFA), weight for age (WFA), and body mass index (BMI) were calculated, indicated by HAZ, WAZ, and BMIZ, respectively. The overall median blood levels of Zn, Ca, Fe, Cu, and Mg were 8.83, 79.02, 9.49, 1.04, and 15.45 mg/L, respectively. Fe, Cu, and Mg increased with age and Zn, Fe, and Cu differed by sex. HAZ and WAZ were positively correlated with Zn (r (2) = 0.072 and 0.053, respectively; P < 0.05). Trace elements were significantly related to children's growth and development. Dietary supplementation and screening of nutritional states are potential solutions to improve children's growth and development.

Trace elements in muscle of three fish species from Todos os Santos Bay, Bahia State, Brazil.

PubMed

de Santana, Carolina Oliveira; de Jesus, Taíse Bomfim; de Aguiar, William Moura; de Jesus Sant'anna Franca-Rocha, Washington; Soares, Carlos Alberto Caroso

2017-03-01

In this study, an analysis was performed on the concentrations of the trace elements Al, As, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V, and Zn in muscle of two carnivorous and one planktivorous fish species collected at Todos os Santos Bay (BTS). The accumulation order of the trace elements in Lutjanus analis was Al >Zn >Fe >Cr >Ba >Ni. In Cetengraulis edentulus, the order was Al >Fe >Zn >Cr >Ni >Mn >As. In the species Diapterus rhombeus, the order was Al >Fe >Zn >Cr >Ni >Mn >Cd. To determine the risk related to the consumption of fish, toxicity guidelines were used as standard references. It was observed that the species C. edentulus contained concentrations of As exceeding WHO limits, but these concentrations were acceptable according to the Agência Nacional de Vigilância Sanitária (ANVISA) guidelines. Cd levels were found only in D. rhombeus and in low concentrations according to the determinations of WHO and ANVISA. Pb levels were not detected in any of the three fish species. The analyzed elements did not differ statistically according to the species and feeding habits. The results point to possible risks of human contamination by As related to the consumption of the fish species C. edentulus from the BTS.

The association between content of the elements S, Cl, K, Fe, Cu, Zn and Br in normal and cirrhotic liver tissue from Danes and Greenlandic Inuit examined by dual hierarchical clustering analysis.

PubMed

Laursen, Jens; Milman, Nils; Pind, Niels; Pedersen, Henrik; Mulvad, Gert

2014-01-01

Meta-analysis of previous studies evaluating associations between content of elements sulphur (S), chlorine (Cl), potassium (K), iron (Fe), copper (Cu), zinc (Zn) and bromine (Br) in normal and cirrhotic autopsy liver tissue samples. Normal liver samples from 45 Greenlandic Inuit, median age 60 years and from 71 Danes, median age 61 years. Cirrhotic liver samples from 27 Danes, median age 71 years. Element content was measured using X-ray fluorescence spectrometry. Dual hierarchical clustering analysis, creating a dual dendrogram, one clustering element contents according to calculated similarities, one clustering elements according to correlation coefficients between the element contents, both using Euclidian distance and Ward Procedure. One dendrogram separated subjects in 7 clusters showing no differences in ethnicity, gender or age. The analysis discriminated between elements in normal and cirrhotic livers. The other dendrogram clustered elements in four clusters: sulphur and chlorine; copper and bromine; potassium and zinc; iron. There were significant correlations between the elements in normal liver samples: S was associated with Cl, K, Br and Zn; Cl with S and Br; K with S, Br and Zn; Cu with Br. Zn with S and K. Br with S, Cl, K and Cu. Fe did not show significant associations with any other element. In contrast to simple statistical methods, which analyses content of elements separately one by one, dual hierarchical clustering analysis incorporates all elements at the same time and can be used to examine the linkage and interplay between multiple elements in tissue samples. Copyright © 2013 Elsevier GmbH. All rights reserved.

Astronaut Bone Medical Standards Derived from Finite Element (FE) Models of QCT Scans from Population Studies

NASA Technical Reports Server (NTRS)

Sibonga, J. D.; Feiveson, A. H.

2014-01-01

This work was accomplished in support of the Finite Element [FE] Strength Task Group, NASA Johnson Space Center [JSC], Houston, TX. This group was charged with the task of developing rules for using finite-element [FE] bone-strength measures to construct operating bands for bone health that are relevant to astronauts following exposure to spaceflight. FE modeling is a computational tool used by engineers to estimate the failure loads of complex structures. Recently, some engineers have used this tool to characterize the failure loads of the hip in population studies that also monitored fracture outcomes. A Directed Research Task was authorized in July, 2012 to investigate FE data from these population studies to derive these proposed standards of bone health as a function of age and gender. The proposed standards make use of an FE-based index that integrates multiple contributors to bone strength, an expanded evaluation that is critical after an astronaut is exposed to spaceflight. The current index of bone health used by NASA is the measurement of areal BMD. There was a concern voiced by a research and clinical advisory panel that the sole use of areal BMD would be insufficient to fully evaluate the effects of spaceflight on the hip. Hence, NASA may not have a full understanding of fracture risk, both during and after a mission, and may be poorly estimating in-flight countermeasure efficacy. The FE Strength Task Group - composed of principal investigators of the aforementioned population studies and of FE modelers -donated some of its population QCT data to estimate of hip bone strength by FE modeling for this specific purpose. Consequently, Human Health Countermeasures [HHC] has compiled a dataset of FE hip strengths, generated by a single FE modeling approach, from human subjects (approx.1060) with ages covering the age range of the astronauts. The dataset has been analyzed to generate a set of FE strength cutoffs for the following scenarios: a) Qualify an applicant for astronaut candidacy, b) Qualify an astronaut for a long-duration (LD) mission, c) Qualify a veteran LD astronaut for a second LD mission, and d) Establish a non-permissible, minimum hip strength following a given mission architecture. This abstract will present the FE-based standards accepted by the FE Strength Task Group for its recommendation to HHC in January 2015.

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

Strauss, H.R.

This paper describes the code FEMHD, an adaptive finite element MHD code, which is applied in a number of different manners to model MHD behavior and edge plasma phenomena on a diverted tokamak. The code uses an unstructured triangular mesh in 2D and wedge shaped mesh elements in 3D. The code has been adapted to look at neutral and charged particle dynamics in the plasma scrape off region, and into a full MHD-particle code.

Effects of Scan Resolutions and Element Sizes on Bovine Vertebral Mechanical Parameters from Quantitative Computed Tomography-Based Finite Element Analysis

PubMed Central

Zhang, Meng; Gao, Jiazi; Huang, Xu; Zhang, Min; Liu, Bei

2017-01-01

Quantitative computed tomography-based finite element analysis (QCT/FEA) has been developed to predict vertebral strength. However, QCT/FEA models may be different with scan resolutions and element sizes. The aim of this study was to explore the effects of scan resolutions and element sizes on QCT/FEA outcomes. Nine bovine vertebral bodies were scanned using the clinical CT scanner and reconstructed from datasets with the two-slice thickness, that is, 0.6 mm (PA resolution) and 1 mm (PB resolution). There were significantly linear correlations between the predicted and measured principal strains (R2 > 0.7, P < 0.0001), and the predicted vertebral strength and stiffness were modestly correlated with the experimental values (R2 > 0.6, P < 0.05). Two different resolutions and six different element sizes were combined in pairs, and finite element (FE) models of bovine vertebral cancellous bones in the 12 cases were obtained. It showed that the mechanical parameters of FE models with the PB resolution were similar to those with the PA resolution. The computational accuracy of FE models with the element sizes of 0.41 × 0.41 × 0.6 mm3 and 0.41 × 0.41 × 1 mm3 was higher by comparing the apparent elastic modulus and yield strength. Therefore, scan resolution and element size should be chosen optimally to improve the accuracy of QCT/FEA. PMID:29065624

Coping with iron limitation: A metabolomic study of Synechocystis sp. PCC 6803

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

Rivas-Ubach, Albert; Poret-Peterson, Amisha T.; Peñuelas, Josep

Iron (Fe) is a key element for all living systems, especially for photosynthetic organisms because of its important role in the photosynthetic electron transport chain. Fe limitation in cyanobacteria leads to several physiological and morphological changes. However, the overall metabolic responses to Fe limitation are still poorly understood. In this study, we integrated elemental, stoichiometric, macromolecular, and metabolomic data to shed light on the responses of Synechocystis sp. PCC 6803, a non-N2-fixing freshwater cyanobacterium, to Fe limitation. Compared to Synechocystis growing at nutrient replete conditions, Fe-limited cultures had lower growth rates and amounts of chlorophyll a, RNA, RNA:DNA, C, N,more » and P and higher ratios of Protein:RNA, C:N, C:P and N:P, in accordance with the growth rate hypothesis which predicts faster growing organisms will have decreased biomass RNA contents and C:P and N:P ratios. Fe-limited Synechocystis had lower amounts Fe, Mn and Mo, and higher amount of Cu. Several changes in amino acids of cultures growing under Fe limitation suggest nitrogen limitation. Additionally, we found substantial increases in stress-related metabolites in Fe-limited cyanobacteria such antioxidants. This study represents an advance in understanding the stoichiometric, macromolecular and metabolic strategies that cyanobacteria use to cope with Fe limitation. This information, moreover, may further understanding of changes in cyanobacterial functions under scenarios of Fe limitation in aquatic ecosystems.« less

Nanocrystalline Fe/Zr alloys: preparation by using mechanical alloying and mechanical milling processes

NASA Astrophysics Data System (ADS)

Rodríguez, V. A. Peña; Medina, J. Medina; Marcatoma, J. Quispe; Ayala, Ch. Rojas; Landauro, C. V.; Baggio-Saitovitch, E. M.; Passamani, E. C.

2011-11-01

Nanocrystalline Fe/Zr alloys have been prepared after milling for 9 h the mixture of elemental Fe and Zr powders or the arc-melting produced Fe2Zr alloy by using mechanical alloying and mechanical milling techniques, respectively. X-ray and Mössbauer results of the Fe and Zr powders, mechanically alloyed, suggest that amorphous Fe2Zr phase and \\upalpha-Fe(Zr) nanograins have been produced with relative concentrations of 91% and 9%, respectively. Conversely, the results of the mechanically milled Fe2Zr alloy indicate that nanograins of the Fe2Zr alloy have been formed, surrounded by a magnetic inter-granular phase that are simultaneously dispersed in a paramagnetic amorphous phase.

A lanthanide-based chemosensor for bioavailable Fe3+ using a fluorescent siderophore: an assay displacement approach.

PubMed

Orcutt, Karen M; Jones, W Scott; McDonald, Andrea; Schrock, David; Wallace, Karl J

2010-01-01

The measurement of trace analytes in aqueous systems has become increasingly important for understanding ocean primary productivity. In oceanography, iron (Fe) is a key element in regulating ocean productivity, microplankton assemblages and has been identified as a causative element in the development of some harmful algal blooms. The chemosenor developed in this study is based on an indicator displacement approach that utilizes time-resolved fluorescence and fluorescence resonance energy transfer as the sensing mechanism to achieve detection of Fe3+ ions as low as 5 nM. This novel approach holds promise for the development of photoactive chemosensors for ocean deployment.

Mercury's core evolution

NASA Astrophysics Data System (ADS)

Deproost, Marie-Hélène; Rivoldini, Attilio; Van Hoolst, Tim

2016-10-01

Remote sensing data of Mercury's surface by MESSENGER indicate that Mercury formed under reducing conditions. As a consequence, silicon is likely the main light element in the core together with a possible small fraction of sulfur. Compared to sulfur, which does almost not partition into solid iron at Mercury's core conditions and strongly decreases the melting temperature, silicon partitions almost equally well between solid and liquid iron and is not very effective at reducing the melting temperature of iron. Silicon as the major light element constituent instead of sulfur therefore implies a significantly higher core liquidus temperature and a decrease in the vigor of compositional convection generated by the release of light elements upon inner core formation.Due to the immiscibility in liquid Fe-Si-S at low pressure (below 15 GPa), the core might also not be homogeneous and consist of an inner S-poor Fe-Si core below a thinner Si-poor Fe-S layer. Here, we study the consequences of a silicon-rich core and the effect of the blanketing Fe-S layer on the thermal evolution of Mercury's core and on the generation of a magnetic field.

Geochemical studies of Fe, Mn, Co, As, Cr, Sb, Zn, Sc and V in surface sediments from Jiaozhou Bay

NASA Astrophysics Data System (ADS)

Wu, Run; Li, Pei-Quan; Miao, Lu-Tian; Zhang, Shu-Xin; Tian, Wei-Zhi

1994-12-01

The contents of nearly forty-elements in surface sediments in Jiaozhou Bay were determined using a Neutron Activation Analysis Technique (Grancini, et al., 1976; Li Peiquan et al., 1985, 1986; Li Xiuxia et al., 1986). This paper's detailed discussion on only nine elements (Fe, Mn, Co, Cr, Sc, As, Sb, Zn and V) includes their distributions, concentrations, correlationships, material sources, background, etc. Based on Zavaristski's classification method, Fe, Mn, Co, Cr and V belong to the second group; As and Sb to the eighth groups: Sc and Zn to the third and sixth groups. It was found that their notably good correlationship is mainly due to the similarity of their ionic structures and that their variation is controlled by the Fe content (except Mn). The source of sediments is mainly terristrial material, and the composition of sediment is similar to that of shale and shale+clay. The contents for a large number of elements are within the scope of the background level, but there still is pollution of Zn and Cr, at least in a few stations.

Major and trace elements in Boletus aereus and Clitopilus prunulus growing on volcanic and sedimentary soils of Sicily (Italy).

PubMed

Alaimo, M G; Dongarrà, G; La Rosa, A; Tamburo, E; Vasquez, G; Varrica, D

2018-08-15

The aim of this study was to determine and compare the content of 28 elements (Ag, Al, As, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, Pb, Rb, Sb, Se, Sr, Tl, U, V and Zn) in fruiting bodies of Boletus aereus Bull. and Clitopilus prunulus P. Kumm collected from eleven unpolluted sites of Sicily (Italy) and, also to relate the abundance of chemical elements in soil with their concentration in mushrooms. Median concentrations of the most abundant elements in Boletus aereus ranged from 31,290 μg/g (K) to 107 μg/g (Zn) in caps and from 24,009 μg/g (K) to 57 μg/g (Zn) in stalks with the following abundance order: K > Na > Ca > Mg > Fe > Al > Rb > Zn. The same elements, in the whole fruiting body of Clitopilus prunulus samples, varied in the range 54,073-92 μg/g following the abundance order: K > Na > Mg > Ca > Fe > Al > Rb > Zn. Metal contents in Boletus aereus and in the whole fruiting body of Clitopilus prunulus, collected from the same sampling sites, showed statistically significant differences for most elements. In particular, Clitopilus prunulus contained around two to four times more Co, Cr, Fe, Mg, Mo, Pb, U and V than caps and stalks of Boletus aereus species which, in turn, was from two to four times more enriched in Cu, Se and Tl. Thus, the elemental content of Boletus aereus and Clitopilus prunulus appeared to be species-dependent. The distribution of chemical elements in Boletus aereus was not uniform throughout the whole fruiting body as most elements were significantly bioconcentrated in caps. Furthermore, the fruit bodies of Boletus aereus from the volcanic soil differed both in major and minor elements concentrations from those collected from sedimentary soils. Cadmium and lead concentrations were below the threshold limits for wild mushrooms proposed by EU Directives (2008 and 2015). The elemental content was not significantly influenced by soil pH. Copyright © 2018 Elsevier Inc. All rights reserved.

Excitation functions of the natCr(p,x)44Ti, 56Fe(p,x)44Ti, natNi(p,x)44Ti and 93Nb(p,x)44Ti reactions at energies up to 2.6 GeV

NASA Astrophysics Data System (ADS)

Titarenko, Yu. E.; Batyaev, V. F.; Pavlov, K. V.; Titarenko, A. Yu.; Zhivun, V. M.; Chauzova, M. V.; Balyuk, S. A.; Bebenin, P. V.; Ignatyuk, A. V.; Mashnik, S. G.; Leray, S.; Boudard, A.; David, J. C.; Mancusi, D.; Cugnon, J.; Yariv, Y.; Nishihara, K.; Matsuda, N.; Kumawat, H.; Stankovskiy, A. Yu.

2016-06-01

The paper presents the measured cumulative yields of 44Ti for natCr, 56Fe, natNi and 93Nb samples irradiated by protons at the energy range 0.04-2.6 GeV. The obtained excitation functions are compared with calculations of the well-known codes: ISABEL, Bertini, INCL4.2+ABLA, INCL4.5+ABLA07, PHITS, CASCADE07 and CEM03.02. The predictive power of these codes regarding the studied nuclides is analyzed.

Benchmark Testing of a New 56Fe Evaluation for Criticality Safety Applications

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

Leal, Luiz C; Ivanov, E.

2015-01-01

The SAMMY code was used to evaluate resonance parameters of the 56Fe cross section in the resolved resonance energy range of 0–2 MeV using transmission data, capture, elastic, inelastic, and double differential elastic cross sections. The resonance analysis was performed with the code SAMMY that fits R-matrix resonance parameters using the generalized least-squares technique (Bayes’ theory). The evaluation yielded a set of resonance parameters that reproduced the experimental data very well, along with a resonance parameter covariance matrix for data uncertainty calculations. Benchmark tests were conducted to assess the evaluation performance in benchmark calculations.

Trace element content and magnetic properties of commercial HOPG samples studied by ion beam microscopy and SQUID magnetometry

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

Spemann, D., E-mail: spemann@uni-leipzig.de; Esquinazi, P., E-mail: esquin@physik.uni-leipzig.de; Setzer, A.

In this study, the impurity concentration and magnetic response of nine highly oriented pyrolytic graphite (HOPG) samples with different grades and from different providers were determined using ion beam microscopy and SQUID magnetometry. Apart from sideface contaminations in the as-received state, bulk contamination of the samples in most cases consists of disk-shaped micron-sized particles made of Ti and V with an additional Fe contamination around the grain perimeter. The saturation magnetization typically increases with Fe concentration, however, there is no simple correlation between Fe content and magnetic moment. The saturation magnetization of one, respectively six, out of nine samples clearlymore » exceeds the maximum contribution from pure Fe or Fe{sub 3}C. For most samples the temperature dependence of the remanence decreases linearly with T – a dependence found previously for defect-induced magnetism (DIM) in HOPG. We conclude that apart from magnetic impurities, additional contribution to the ferromagnetic magnetization exists in pristine HOPG in agreement with previous studies. A comparative study between the results of ion beam microscopy and the commonly used EDX analysis shows clearly that EDX is not a reliable method for quantitative trace elemental analysis in graphite, clarifying weaknesses and discrepancies in the element concentrations given in the recent literature.« less

New magnetic rails with double-layer Halbach structure by employing NdFeB and ferrite magnets for HTS maglev

NASA Astrophysics Data System (ADS)

Sun, Ruixue; Zheng, Jun; Zheng, Botian; Qian, Nan; Li, Jipeng; Deng, Zigang

2018-01-01

In the high temperature superconducting (HTS) maglev system, the magnetic rail as an essential infrastructure is needed all along the route to carry passengers and goods to the destinations. Thus, large amount of rare earth magnetic materials are required in the magnetic rail construction. In order to decrease the dependence of magnetic rails on rare earth elements, the ferrite magnet is employed to replace part of the NdFeB magnets containing rare earth elements. Consequently, a new type rail with double-layer Halbach structure is presented, which is consisted of NdFeB and ferrite magnets. In this paper, we designed and fabricated the proposed rail, and further measured its magnetic flux density distribution and electromagnetic force interacting with HTS bulks. Experimental results indicate that, this new type rail, in double-layer Halbach structure, can achieve an equivalent distribution of magnetic flux density and levitation performance as the pure NdFeB Halbach rail, while a 10% reduction in NdFeB magnet consumption can be realized at the same time. In addition this work explores another magnetic material selection for HTS maglev applications. The dependence on rare earth element and the cost of magnetic rails can be further reduced, as the coercive force of ferrite magnets improved.

Strategic coating of NdFeB magnets with Dy to improve the coercivity of permanent magnets

DOE PAGES

Ucar, Huseyin; Parker, David S.; Nlebedim, I. C.; ...

2015-12-25

Here, we present a method, supported by theoretical analysis, for optimizing the usage of the critical rare earth element dysprosium in Nd 2Fe 14B (NdFeB)-based permanent magnets. In this method, we use Dy selectively in locations such as magnet edges and faces, where demagnetization factors are most significant, rather than uniformly throughout the bulk sample. A 200 nm thick Dy film was sputtered onto commercial N-38, NdFeB magnets with a thickness of 3 mm and post-annealed at temperatures from 600 - 700 C. Magnets displayed enhanced coercivities after post-annealing. Furthermore, our experimental results indicate as large as a 5 percentmore » increase in the energy product of NdFeB magnets, achieved for a total Dy weight percentage of 0.06 percent, much less than that used in commercial grade Dy-NdFeB magnets. Finally, by assuming all Dy diffused into NdFeB magnets, the improvement in energy product corresponds to a saving of over 1% Dy (critical element). Magnets manufactured using this technique will therefore be higher performing and significantly less expensive than those made presently.« less

Federal Logistics Information Systems. FLIS Procedures Manual. Document Identifier Code Input/Output Formats (Variable Length). Volume 9.

DTIC Science & Technology

1997-04-01

DATA COLLABORATORS 0001N B NQ 8380 NUMBER OF DATA RECEIVERS 0001N B NQ 2533 AUTHORIZED ITEM IDENTIFICATION DATA COLLABORATOR CODE 0002 ,X B 03 18 TD...01 NC 8268 DATA ELEMENT TERMINATOR CODE 000iX VT 9505 TYPE OF SCREENING CODE 0001A 01 NC 8268 DATA ELEMENT TERMINATOR CODE 000iX VT 4690 OUTPUT DATA... 9505 TYPE OF SCREENING CODE 0001A 2 89 2910 REFERENCE NUMBER CATEGORY CODE (RNCC) 0001X 2 89 4780 REFERENCE NUMBER VARIATION CODE (RNVC) 0001 N 2 89

Application of thin-plate spline transformations to finite element models, or, how to turn a bog turtle into a spotted turtle to analyze both.

PubMed

Stayton, C Tristan

2009-05-01

Finite element (FE) models are popular tools that allow biologists to analyze the biomechanical behavior of complex anatomical structures. However, the expense and time required to create models from specimens has prevented comparative studies from involving large numbers of species. A new method is presented for transforming existing FE models using geometric morphometric methods. Homologous landmark coordinates are digitized on the FE model and on a target specimen into which the FE model is being transformed. These coordinates are used to create a thin-plate spline function and coefficients, which are then applied to every node in the FE model. This function smoothly interpolates the location of points between landmarks, transforming the geometry of the original model to match the target. This new FE model is then used as input in FE analyses. This procedure is demonstrated with turtle shells: a Glyptemys muhlenbergii model is transformed into Clemmys guttata and Actinemys marmorata models. Models are loaded and the resulting stresses are compared. The validity of the models is tested by crushing actual turtle shells in a materials testing machine and comparing those results to predictions from FE models. General guidelines, cautions, and possibilities for this procedure are also presented.

Variation of magnetic properties with mischmetal content in the resource saving magnets of MM-Fe-B ribbons

NASA Astrophysics Data System (ADS)

Li, Zhu-bai; Wang, Li-chen; Geng, Xiao-peng; Hu, Feng-xia; Sun, Ji-rong; Shen, Bao-gen

2017-03-01

Magnetic materials of MM-Fe-B (MM=mischmetal) ribbons were prepared using melt spinning method by varying the content of MM. The ribbons contain minor phases besides the main phase of Re2Fe14B. X-ray techniques show that the diffraction peak intensities of the minor phase Fe3B vary with the content of constituent elements, indicating that the amount of minor phase could be tunable. The squareness of hysteresis loop is the best in MM13Fe80.5B6.5 ribbons, which should mainly ascribe to the less amount of minor phase. Henkel plots verify the more uniform magnetization reversals in MM13Fe80.5B6.5 ribbons, and the energy product achieves to the maximum of 12.74 MGOe with the coercivity of 6.50 kOe. With the increase of MM content the coercivity increases monotonically, and reaches to 9.13 kOe in MM15Fe77.5B7.5 ribbons, which should be related with the nature of the defects in the main phase. These investigations show that optimizing the content of constituent elements and phase constitution could improve magnetic properties in the resource-saving magnets of MM-Fe-B ribbons.

Effect of Nb on magnetic and mechanical properties of TbDyFe alloys

NASA Astrophysics Data System (ADS)

Wang, Naijuan; Liu, Yuan; Zhang, Huawei; Chen, Xiang; Li, Yanxiang

2018-03-01

The intrinsic brittleness in giant magnetostrictive material TbDyFe alloy has devastating influence on the machinability and properties of the alloy, thus affecting its applications. The purpose of this paper is to study the mechanical properties of the TbDyFe alloy by alloying with Nb element. The samples (Tb0.3Dy0.7)xFe2xNby (y = 0, 0.01, 0.04, 0.07, 0.1; 3x + y = 1) were melted in an arc melting furnace under high purity argon atmosphere. The microstructure, magnetostrictive properties and mechanical performance of the alloys were studied systematically. The results showed that NbFe2 phases were observed in the alloys with the addition of Nb. Moreover, both the NbFe2 phases and rare earth (RE)-rich phases were increased with the increasing of Nb element. The mechanical properties results revealed that the fracture toughness of the alloy with the addition of Nb enhanced 1.5-5 times of the Nb-free alloy. Both the NbFe2 phase and the RE-rich phase had the ability to prevent crack propagation, so that they can strengthen the REFe2 body. However, NbFe2 phase is a paramagnetic phase, which can reduce the magnetostrictive properties of the alloy by excessive precipitation.

The effects of Ni, Mo, Ti and Si on the mechanical properties of Cr free Mn steel (Fe-25Mn-5Al-2C)

NASA Technical Reports Server (NTRS)

Schuon, S. R.

1982-01-01

The FeMnAlC alloys may hold potential as Cr-free replacements for high strategic material iron base superalloys, but little is known about their intermediate temperature (650 C to 870 C) mechanical properties. The effects of alloying elements on the mechanical properties of model FeMnAlC alloys were studied. Results showed that modified FeMnAlC alloys had promising short term, intermediate temperature properties but had relatively poor stress rupture lives at 172 MPa and 788 C. Room temperature and 788 C tensile strength of FeMnAlC alloys were better than common cast stainless steels. Changes in room temperature tensile and 788 C tensile strength and ductility, and 788 C stress rupture life were correlated with changes in Ni, Mo, Ti, and Si levels due to alloying effects on interstitial carbon levels and carbide morphology. Fe-25Mn-5Al-2C had a very poor stress rupture life at 172 MPa and 788 C. Addition of carbide-forming elements improved the stress rupture life.

Weathering and precipitation after meteorite impact of Ni, Cr, Fe, Ca and Mn in K-T boundary clays from Stevns Klint

NASA Astrophysics Data System (ADS)

Miyano, Yumiko; Yoshiasa, Akira; Tobase, Tsubasa; Isobe, Hiroshi; Hongu, Hidetomo; Okube, Maki; Nakatsuka, Akihiko; Sugiyama, Kazumasa

2016-05-01

Ni, Cr, Fe, Ca and Mn K-edge XANES and EXAFS spectra were measured on K-T boundary clays from Stevns Klint in Denmark. According to XANES spectra and EXAFS analyses, the local structures of Ni, Cr and Fe in K-T boundary clays is similar to Ni(OH)2, Cr2O3 and FeOOH, respectively. It is assumed that the Ni, Cr and Fe elements in impact related glasses is changing into stable hydrate and oxide by the weathering and diagenesis at the surface of the Earth. Ca in K-T boundary clays maintains the diopside-like structure. Local structure of Ca in K-T clays seems to keep information on the condition at meteorite impact. Mn has a local structure like MnCO3 with divalent state. It is assumed that the origin on low abundant of Mn in the Fe-group element in K-T clays was the consumption by life activity and the diffusion to other parts.

Density of Fe-3.5 wt% C liquid at high pressure and temperature and the effect of carbon on the density of the molten iron

NASA Astrophysics Data System (ADS)

Shimoyama, Yuta; Terasaki, Hidenori; Ohtani, Eiji; Urakawa, Satoru; Takubo, Yusaku; Nishida, Keisuke; Suzuki, Akio; Katayama, Yoshinori

2013-11-01

Carbon is a plausible light element candidate in the Earth’s outer core. We measured the density of liquid Fe-3.5 wt% C up to 6.8 GPa and 2200 K using an X-ray absorption method. The compression curve of liquid Fe-C was fitted using the third-order Birch-Murnaghan equation of state. The bulk modulus and its pressure derivative are K0,1500K = 55.3 ± 2.5 GPa and (dK0/dP)T = 5.2 ± 1.5, and the thermal expansion coefficient is α = 0.86 ± 0.04 × 10-4 K-1. The Fe-C density abruptly increases at pressures between 4.3 and 5.5 GPa in the range of present temperatures. Compared with the results of previous density measurements of liquid Fe-C, the effect of carbon on the density of liquid Fe shows a nonideal mixing behavior. The abrupt density increase and nonideal mixing behavior are important factors in determining the light element content in the Earth’s core.

Novel Experimental Simulations of the Atmospheric Injection of Meteoric Metals

NASA Astrophysics Data System (ADS)

Gómez Martín, J. C.; Bones, D. L.; Carrillo-Sánchez, J. D.; James, A. D.; Trigo-Rodríguez, J. M.; Fegley, B., Jr.; Plane, J. M. C.

2017-02-01

A newly developed laboratory, Meteoric Ablation Simulator (MASI), is used to test model predictions of the atmospheric ablation of interplanetary dust particles (IDPs) with experimental Na, Fe, and Ca vaporization profiles. MASI is the first laboratory setup capable of performing time-resolved atmospheric ablation simulations, by means of precision resistive heating and atomic laser-induced fluorescence detection. Experiments using meteoritic IDP analogues show that at least three mineral phases (Na-rich plagioclase, metal sulfide, and Mg-rich silicate) are required to explain the observed appearance temperatures of the vaporized elements. Low melting temperatures of Na-rich plagioclase and metal sulfide, compared to silicate grains, preclude equilibration of all the elemental constituents in a single melt. The phase-change process of distinct mineral components determines the way in which Na and Fe evaporate. Ca evaporation is dependent on particle size and on the initial composition of the molten silicate. Measured vaporized fractions of Na, Fe, and Ca as a function of particle size and speed confirm differential ablation (I.e., the most volatile elements such as Na ablate first, followed by the main constituents Fe, Mg, and Si, and finally the most refractory elements such as Ca). The Chemical Ablation Model (CABMOD) provides a reasonable approximation to this effect based on chemical fractionation of a molten silicate in thermodynamic equilibrium, even though the compositional and geometric description of IDPs is simplistic. Improvements in the model are required in order to better reproduce the specific shape of the elemental ablation profiles.

Algebraic multigrid preconditioning within parallel finite-element solvers for 3-D electromagnetic modelling problems in geophysics

NASA Astrophysics Data System (ADS)

Koldan, Jelena; Puzyrev, Vladimir; de la Puente, Josep; Houzeaux, Guillaume; Cela, José María

2014-06-01

We present an elaborate preconditioning scheme for Krylov subspace methods which has been developed to improve the performance and reduce the execution time of parallel node-based finite-element (FE) solvers for 3-D electromagnetic (EM) numerical modelling in exploration geophysics. This new preconditioner is based on algebraic multigrid (AMG) that uses different basic relaxation methods, such as Jacobi, symmetric successive over-relaxation (SSOR) and Gauss-Seidel, as smoothers and the wave front algorithm to create groups, which are used for a coarse-level generation. We have implemented and tested this new preconditioner within our parallel nodal FE solver for 3-D forward problems in EM induction geophysics. We have performed series of experiments for several models with different conductivity structures and characteristics to test the performance of our AMG preconditioning technique when combined with biconjugate gradient stabilized method. The results have shown that, the more challenging the problem is in terms of conductivity contrasts, ratio between the sizes of grid elements and/or frequency, the more benefit is obtained by using this preconditioner. Compared to other preconditioning schemes, such as diagonal, SSOR and truncated approximate inverse, the AMG preconditioner greatly improves the convergence of the iterative solver for all tested models. Also, when it comes to cases in which other preconditioners succeed to converge to a desired precision, AMG is able to considerably reduce the total execution time of the forward-problem code-up to an order of magnitude. Furthermore, the tests have confirmed that our AMG scheme ensures grid-independent rate of convergence, as well as improvement in convergence regardless of how big local mesh refinements are. In addition, AMG is designed to be a black-box preconditioner, which makes it easy to use and combine with different iterative methods. Finally, it has proved to be very practical and efficient in the parallel context.

PIXE as a complement to ICP-OES trace metal analysis in Sudanese medicinal plants.

PubMed

Mubark Ebrahim, Ammar; Etayeb, M A; Khalid, H; Noun, Manale; Roumie, M; Michalke, B

2014-08-01

This paper compares trace element concentrations (Ca, K, Sr, Fe, Mn, Zn, Ni, Cu, Co and Cr) in 27 Sudanese medical plants determined in parallel by PIXE and ICP-OES to get information on which technique is preferable at different matrices and element concentrations. PIXE correlates well to ICP-OES for Sr, Mn, Ca, K, Zn and Fe determinations. ICP-OES seems to be the superior technique over PIXE when measuring low concentrated elements (chromium, cobalt, nickel and copper) in the medicinal plants. Copyright © 2014 Elsevier Ltd. All rights reserved.

Trace-element evidence for the origin of desert varnish by direct aqueous atmospheric deposition

NASA Astrophysics Data System (ADS)

Thiagarajan, Nivedita; Aeolus Lee, Cin-Ty

2004-07-01

Smooth rock surfaces in arid environments are often covered with a thin coating of Fe-Mn oxyhydroxides known as desert varnish. It is debated whether such varnish is formed (a) by slow diagenesis of dust particles deposited on rock surfaces, (b) by leaching from the underlying rock substrate, or (c) by direct deposition of dissolved constituents in the atmosphere. Varnishes collected from smooth rock surfaces in the Mojave Desert and Death Valley, California are shown here to have highly enriched and fractionated trace-element abundances relative to upper continental crust (UCC). They are highly enriched in Co, Ni, Pb and the rare-earth elements (REEs). In particular, they have anomalously high Ce/La and low Y/Ho ratios. These features can only be explained by preferential scavenging of Co, Ni, Pb and the REEs by Fe-Mn oxyhydroxides in an aqueous environment. High field strength elements (HFSEs: Zr, Hf, Ta, Nb, Th), however, show only small enrichments despite the fact that these elements should also be strongly scavenged by Fe-Mn oxyhydroxides. This suggests that their lack of enrichment is a feature inherited from a solution initially poor in HFSEs. The first two scenarios for varnish formation can be ruled out as follows. The high enrichment factors of Fe, Mn and many trace elements cannot be generated by mass loss associated with post-depositional diagenesis of dust particles because such a process predicts only a small increase in concentration. In addition, the highly fractionated abundance patterns of particle reactive element pairs (e.g., Ce/La and Y/Ho) rules out leaching of the rock substrate. This is because if leaching were to occur, varnishes would grow from the inside to the outside, and thus any particle-reactive trace element leached from the substrate would be quantitatively sequestered in the Fe-Mn oxyhydroxide layers, prohibiting any significant elemental fractionations. One remaining possibility is that the Fe, Mn and trace metals in varnish are derived from leaching of dust particles entrained in rain or fog droplets either in the atmosphere or during wet atmospheric deposition. The high trace metal enrichment factors require that most of the dust was physically removed before or during varnish formation. The remaining aqueous counterpart would be depleted in HFSEs and Th relative to the REEs, Co, Ni and Pb because the former are more insoluble and hence largely retained in the removed dust fraction. The high Ce/La ratios suggest that precipitation of trace metals may have been governed by equilibrium partitioning in an excess of wet atmospheric deposition. If varnishes are indeed derived from wet atmospheric deposition, they may provide a record of the aqueous component of atmospheric dust inputs to various environments.

Critical evaluation and thermodynamic optimization of the Iron-Rare-Earth systems

NASA Astrophysics Data System (ADS)

Konar, Bikram

Rare-Earth elements by virtue of its typical magnetic, electronic and chemical properties are gaining importance in power, electronics, telecommunications and sustainable green technology related industries. The Magnets from RE-alloys are more powerful than conventional magnets which have more longevity and high temperature workability. The dis-equilibrium in the Rare-Earth element supply and demand has increased the importance of recycling and extraction of REE's from used permanent Magnets. However, lack of the thermodynamic data on RE alloys has made it difficult to design an effective extraction and recycling process. In this regard, Computational Thermodynamic calculations can serve as a cost effective and less time consuming tool to design a waste magnet recycling process. The most common RE permanent magnet is Nd magnet (Nd 2Fe14B). Various elements such as Dy, Tb, Pr, Cu, Co, Ni, etc. are also added to increase its magnetic and mechanical properties. In order to perform reliable thermodynamic calculations for the RE recycling process, accurate thermodynamic database for RE and related alloys are required. The thermodynamic database can be developed using the so-called CALPHAD method. The database development based on the CALPHAD method is essentially the critical evaluation and optimization of all available thermodynamic and phase diagram data. As a results, one set of self-consistent thermodynamic functions for all phases in the given system can be obtained, which can reproduce all reliable thermodynamic and phase diagram data. The database containing the optimized Gibbs energy functions can be used to calculate complex chemical reactions for any high temperature processes. Typically a Gibbs energy minimization routine, such as in FactSage software, can be used to obtain the accurate thermodynamic equilibrium in multicomponent systems. As part of a large thermodynamic database development for permanent magnet recycling and Mg alloy design, all thermodynamic and phase diagram data in the literature for the fourteen Fe-RE binary systems: Fe-La, Fe-Ce, Fe-Pr, Fe-Nd, Fe-Sm, Fe-Gd, Fe-Tb, Fe-Dy, Fe-Ho, Fe-Er, Fe-Tm, Fe-Lu, Fe-Sc and Fe-Y are critically evaluated and optimized to obtain thermodynamic model parameters. The model parameters can be used to calculate phase diagrams and Gibbs energies of all phases as functions of temperature and composition. This database can be incorporated with the present thermodynamic database in FactSage software to perform complex chemical reactions and phase diagram calculations for RE magnet recycling process.

Combined effects of low-molecular-weight organic acids on mobilization of arsenic and lead from multi-contaminated soils.

PubMed

Onireti, Olaronke O; Lin, Chuxia; Qin, Junhao

2017-03-01

A batch experiment was conducted to examine the combined effects of three common low-molecular-weight organic acids (LMWOAs) on the mobilization of arsenic and lead in different types of multi-contaminated soils. The capacity of individual LMWOAs (at a same molar concentration) to mobilize soil-borne As and Pb varied significantly. The combination of the organic acids did not make a marked "additive" effect on the mobilization of the investigated three elements. An "antagonistic" effect on element mobilization was clear in the treatments involving oxalic acid for some soils. The acid strength of a LMWOA did not play an important role in controlling the mobilization of elements. While the mobilization of As and Pb was closely associated with the dissolution of soil-borne Fe, soil properties such as original soil pH, organic matter contents and the total amount of the element relative to the total Fe markedly complicated the mobility of that element. Aging led to continual consumption of proton introduced from addition of LMWOAs and consequently caused dramatic changes in solution-borne Fe, which in turn resulted in change in As and Pb in the soil solution though different elements behaved differently. Copyright © 2016 Elsevier Ltd. All rights reserved.

Hot-pressed production and laser properties of ZnSe:Fe2+

NASA Astrophysics Data System (ADS)

Avetisov, R. I.; Balabanov, S. S.; Firsov, K. N.; Gavrishchuk, E. M.; Gladilin, A. A.; Ikonnikov, V. B.; Kalinushkin, V. P.; Kazantsev, S. Yu.; Kononov, I. G.; Zykova, M. P.; Mozhevitina, E. N.; Khomyakov, A. V.; Savin, D. V.; Timofeeva, N. A.; Uvarov, O. V.; Avetissov, I. Ch.

2018-06-01

A new approach for fabrication of laser elements in form of plates based on ZnSe:Fe2+ with undoped faces, combining the advantages of hot pressing and diffusion techniques has been proposed. CVD-ZnSe was used as a host material. 1 μm Fe film was deposited by electron-beam technique on one side of the polished CVD-ZnSe plate (20 mm in diameter and 2 mm in thickness). The elements were stacked in contact by iron surfaces, placed in a hot press-mold die, heated under vacuum to 1000 °C, exposed during 60 min with the application of 25 MPa uniaxial pressure. The iron film was dissolved in ZnSe matrix and elements welded together. The samples were subjected to hot isostatic pressing (HIP) during 29 h at 100 MPa argon pressure and 1300 °C. The influence of sintering and HIP processing conditions on local morphology and properties of the interface of welded elements was studied by SEM, TEM and optical microscopy. For all composite elements the lasing was obtained at a pumping by HF-laser at RT with high efficiency around 40%. The proposed technique removes restrictions on the size of laser elements and appears to be very promising for the management of the distribution profile of the doping component.

A computer code for calculations in the algebraic collective model of the atomic nucleus

NASA Astrophysics Data System (ADS)

Welsh, T. A.; Rowe, D. J.

2016-03-01

A Maple code is presented for algebraic collective model (ACM) calculations. The ACM is an algebraic version of the Bohr model of the atomic nucleus, in which all required matrix elements are derived by exploiting the model's SU(1 , 1) × SO(5) dynamical group. This paper reviews the mathematical formulation of the ACM, and serves as a manual for the code. The code enables a wide range of model Hamiltonians to be analysed. This range includes essentially all Hamiltonians that are rational functions of the model's quadrupole moments qˆM and are at most quadratic in the corresponding conjugate momenta πˆN (- 2 ≤ M , N ≤ 2). The code makes use of expressions for matrix elements derived elsewhere and newly derived matrix elements of the operators [ π ˆ ⊗ q ˆ ⊗ π ˆ ] 0 and [ π ˆ ⊗ π ˆ ] LM. The code is made efficient by use of an analytical expression for the needed SO(5)-reduced matrix elements, and use of SO(5) ⊃ SO(3) Clebsch-Gordan coefficients obtained from precomputed data files provided with the code.

Resin Film Infusion (RFI) Process Modeling for Large Transport Aircraft Wing Structures

NASA Technical Reports Server (NTRS)

Loos, Alfred C.; Caba, Aaron C.; Furrow, Keith W.

2000-01-01

This investigation completed the verification of a three-dimensional resin transfer molding/resin film infusion (RTM/RFI) process simulation model. The model incorporates resin flow through an anisotropic carbon fiber preform, cure kinetics of the resin, and heat transfer within the preform/tool assembly. The computer model can predict the flow front location, resin pressure distribution, and thermal profiles in the modeled part. The formulation for the flow model is given using the finite element/control volume (FE/CV) technique based on Darcy's Law of creeping flow through a porous media. The FE/CV technique is a numerically efficient method for finding the flow front location and the fluid pressure. The heat transfer model is based on the three-dimensional, transient heat conduction equation, including heat generation. Boundary conditions include specified temperature and convection. The code was designed with a modular approach so the flow and/or the thermal module may be turned on or off as desired. Both models are solved sequentially in a quasi-steady state fashion. A mesh refinement study was completed on a one-element thick model to determine the recommended size of elements that would result in a converged model for a typical RFI analysis. Guidelines are established for checking the convergence of a model, and the recommended element sizes are listed. Several experiments were conducted and computer simulations of the experiments were run to verify the simulation model. Isothermal, non-reacting flow in a T-stiffened section was simulated to verify the flow module. Predicted infiltration times were within 12-20% of measured times. The predicted pressures were approximately 50% of the measured pressures. A study was performed to attempt to explain the difference in pressures. Non-isothermal experiments with a reactive resin were modeled to verify the thermal module and the resin model. Two panels were manufactured using the RFI process. One was a stepped panel and the other was a panel with two 'T' stiffeners. The difference between the predicted infiltration times and the experimental times was 4% to 23%.

Chemical composition of drinking water as a possible environment-specific factor modifying the thyroid risk in the areas subjected to radioiodine contamination

NASA Astrophysics Data System (ADS)

Kolmykova, Lyudmila; Korobova, Elena; Ryzhenko, Boris

2015-04-01

Water is one of the main natural agents providing chemical elements' migration in the environment and food chains. In our opinion a study of spatial variation of the essential trace elements in local drinking water is worth considering as the factor that may contribute to variation of the health risk in areas contaminated by radionuclides and radioiodine in particular. Radioiodine was proved to increase the risk of thyroid cancer among children who lived in areas contaminated during the Chernobyl accident. It was also shown that low stable iodine status of the contaminated area and population also contributed to the risk of this disease in case of radionuclide contamination. The goal of the study was to investigate chemical composition of the drinking water in rural settlements of the Bryansk oblast' subjected to radioiodine contamination and to evaluate speciation of stable I and Se on the basis of their total concentration and chemical composition of the real water samples with the help of thermodynamic modelling. Water samples were collected from different aquifers discharging at different depths (dug wells, local private bore holes and water pipes) in rural settlements located in areas with contrasting soil iodine status. Thermodynamic modelling was performed using original software (HCh code of Y.Shvarov, Moscow State University, RUSSIA) incorporating the measured pH, Corg and elements' concentration values. Performed modelling showed possibility of formation of complex CaI+ ion in aqueous phase, I sorption by goethite and transfer of Se to solid phase as FeSe in the observed pH-Eh conditions. It helped to identify environmental conditions providing high I and Se mobility and their depletion from natural waters. Both the experimental data and modeling showed that I and Se migration and deficiency in natural water is closely connected to pH, Eh conditions and the concentration of typomorphic chemical elements (Ca, Mg, Fe) defining the class of water migration in landscapes (according Perel'man, 1975). Obtained data will be used for evaluation of contribution of I and Se status of drinking water to the risk of thyroid diseases among local population.

Molecular beam epitaxy growth of SmFeAs(O,F) films with Tc = 55 K using the new fluorine source FeF3

NASA Astrophysics Data System (ADS)

Sakoda, Masahito; Ishii, Akihiro; Takinaka, Kenji; Naito, Michio

2017-07-01

REFeAs(O,F) (RE: rare-earth element) has the highest-Tc (˜58 K) among the iron-based superconductors, but a thin-film growth of REFeAs(O,F) is difficult. This is because it is not only a complex compound consisting of five elements but also requires doping of highly reactive fluorine to achieve superconductivity. We have reported in our previous article that fluorine can be supplied to a film by subliming solid-state fluorides such as FeF2 or SmF3. In this article, we report on the growth of SmFeAs(O,F) using FeF3 as an alternative fluorine source. FeF3 is solid at ambient temperatures and decomposes at temperatures as low as 100-200 °C, and releases fluorine-containing gas during the thermal decomposition. With this alternative fluorine source, we have grown SmFeAs(O,F) films with Tc as high as 55 K. This achievement demonstrates that FeF3 has potential as a fluorine source that can be employed ubiquitously for a thin-film growth of any fluorine containing compounds. One problem specific to FeF3 is that the compound is highly hydroscopic and contains a substantial amount of water even in its anhydrous form. In this article, we describe how to overcome this specific problem.

40 CFR Appendix A to Subpart A of... - Tables

Code of Federal Regulations, 2011 CFR

2011-07-01

... precursor of PM2.5. Table 2a to Appendix A of Subpart A—Data Elements for Reporting on Emissions From Point Sources, Where Required by 40 CFR 51.30 Data elements Every-yearreporting Three-yearreporting (1... phone number ✓ ✓ (6) FIPS code ✓ ✓ (7) Facility ID codes ✓ ✓ (8) Unit ID code ✓ ✓ (9) Process ID code...

Minor and trace element concentrations in adjacent kamacite and taenite in the Krymka chondrite

NASA Astrophysics Data System (ADS)

Meftah, N.; Mostefaoui, S.; Jambon, A.; Guedda, E. H.; Pont, S.

2016-04-01

We report in situ NanoSIMS siderophile minor and trace element abundances in individual Fe-Ni metal grains in the unequilibrated chondrite Krymka (LL3.2). Associated kamacite and taenite of 10 metal grains in four chondrules and one matrix metal were analyzed for elemental concentrations of Fe, Ni, Co, Cu, Rh, Ir, and Pt. The results show large elemental variations among the metal grains. However, complementary and correlative variations exist between adjacent kamacite-taenite. This is consistent with the unequilibrated character of the chondrite and corroborates an attainment of chemical equilibrium between the metal phases. The calculated equilibrium temperature is 446 ± 9 °C. This is concordant with the range given by Kimura et al. (2008) for the Krymka postaccretion thermal metamorphism. Based on Ni diffusivity in taenite, a slow cooling rate is estimated of the Krymka parent body that does not exceed ~1K Myr-1, which is consistent with cooling rates inferred by other workers for unequilibrated ordinary chondrites. Elemental ionic radii might have played a role in controlling elemental partitioning between kamacite and taenite. The bulk compositions of the Krymka metal grains have nonsolar (mostly subsolar) element/Ni ratios suggesting the Fe-Ni grains could have formed from distinct precursors of nonsolar compositions or had their compositions modified subsequent to chondrule formation events.

High Pressure and Temperature Core Formation as an Alternative to the "Late Veneer" Hypothesis

NASA Technical Reports Server (NTRS)

Righter, Kevin; Pando, K.; Humayun, M.; Danielson, L.

2011-01-01

The highly siderophile elements (HSE; Re, Au and the Platinum Group Elements - Pd Pt, Rh, Ru, Ir, Os) are commonly utilized to constrain accretion processes in terrestrial differentiated bodies due to their affinity for FeNi metal [1]. These eight elements exhibit highly siderophile behavior, but nonetheless have highly diverse metal-silicate partition coefficients [2]. Therefore the near chondritic relative concentrations of HSEs in the terrestrial and lunar mantles, as well as some other bodies, are attributed to late accretion rather than core formation [1]. Evaluation of competing theories, such as high pressure metal-silicate partitioning or magma ocean hypotheses has been hindered by a lack of relevant partitioning data for this group of eight elements. In particular, systematic studies isolating the effect of one variable (e.g. temperature or melt compositions) are lacking. Here we undertake new experiments on all eight elements, using Fe metal and FeO-bearing silicate melts at fixed pressure, but variable temperatures. These experiments, as well as some additional planned experiments should allow partition coefficients to be more accurately calculated or estimated at the PT conditions and compositions at which core formation is thought to have occurred.

Potentially toxic elements (PTEs) in soils from the surroundings of the Trans-Amazonian Highway, Brazil.

PubMed

de Souza, Edna Santos; Fernandes, Antonio Rodrigues; de Souza Braz, Anderson Martins; Sabino, Lorena Lira Leite; Alleoni, Luís Reynaldo Ferracciú

2015-01-01

The Trans-Amazonian Highway (TAH) is located in the northern region of Brazil, comprising a border region where agricultural, mining, and logging activities are the main activities responsible for fostering economic development, in addition to large hydroelectric plants. Such activities lead to environmental contamination by potentially toxic elements (PTEs). Environmental monitoring is only possible through the determination of element contents under natural conditions. Many extraction methods have been proposed to determine PTEs' bioavailability in the soil; however, there is no consensus about which extractor is most suitable. In this study, we determined the contents of PTEs in soils in the surroundings of TAH after mineral extraction with diethylenetriaminepentaacetic acid-triethanolamine (DTPA-TEA), Mehlich I, and Mehlich III solutions. Soil samples were collected in areas of natural vegetation in the vicinity of TAH in the state of Pará, Brazil. Chemical attributes and particle size were determined, besides concentrations of Fe, Al, Mn, and Ti by sulfuric acid digestion, Si after alkaline solution attack, and poorly crystalline Fe, Al, and "free" Fe oxides. Mehlich III solution extracted greater contents from Fe, Al, and Pb as compared to Mehlich I and DTPA-TEA and similar contents from Cd, Mn, Zn, and Cu. Significant correlations were found between concentrations of PTEs and the contents of Fe and Mn oxides as well as organic carbon and soil cation exchange capacity. Contents of Cu, Mn, Fe, and Zn by the three methods were positively correlated.

Effectiveness of fortification of corn flour-derived products with hydrogen-reduced elemental iron on iron-deficiency anaemia in children and adolescents in southern Brazil.

PubMed

Miglioranza, Lúcia H S; Breganó, José Wander; Dichi, Isaias; Matsuo, Tiemi; Dichi, Jane Bandeira; Barbosa, Décio Sabbatini

2009-02-01

To find the ideal combination of Fe fortifier and its food vehicle is an essential measure in developing countries. However, its cost also plays an important role. In the present study, the effect on blood parameter values of corn flour-derived products fortified with powdered elemental Fe in the form of H2-reduced Fe was investigated in children and adolescents. One hundred and sixty-two individuals (eighty-six boys and seventy-six girls) from public educational centres in Londrina, Paraná (southern Brazil) participated in the study. Fe-deficiency anaemia (IDA) was defined when Hb and serum ferritin values fell below 12 g/dl and 20 microg/l, respectively; Fe deficiency (ID) was considered when serum ferritin was below 20 microg/l. The prevalence of ID and IDA decreased from 18.0 % and 14.9 %, values found at the beginning of the study, to respectively 5.6 % and 1.2 % after 6 months. Changes from altered to normal values occurred more often than normal to altered values with transferrin saturation (14.2 % v. 6.8 %; P < 0.04) and ferritin (12.4 % v. 0 %; P < 0.001). Hb, transferrin saturation and ferritin showed differences between normal and altered parameters after 6 months (P < 0.001). A pronounced reduction in the prevalence of ID and IDA was observed in children and adolescents following 6 months' ingestion of corn flour-derived products enriched with elemental Fe.

Ferric iron in sediments as a novel CO2 mineral trap: CO 2-SO2 reaction with hematite

USGS Publications Warehouse

Palandri, J.L.; Rosenbauer, R.J.; Kharaka, Y.K.

2005-01-01

Thermodynamic simulations of reactions among SO2-bearing CO 2-dominated gas, water and mineral phases predict that Fe III in sediments should be converted almost entirely to dissolved FeII and siderite (FeCO3), and that SO2 should simultaneously be oxidized to dissolved sulfate. The reactions are however, subject to kinetic constraints which may result in deviation from equilibrium and the precipitation of other metastable mineral phases. To test the prediction, a laboratory experiment was carried out in a well stirred hydrothermal reactor at 150??C and 300 bar with hematite, 1.0 m NaCl, 0.5 m NaOH, SO2 in quantity sufficient to reduce much of the iron, and excess CO2. The experiment produced stable siderite and metastable pyrite and elemental S. Changes in total dissolved Fe are consistent with nucleation of pyrite at ???17 h, and nucleation of siderite at ???600 h. Dissolution features present on elemental S at the conclusion of the experiment suggest nucleation early in the experiment. The experiment did not reach equilibrium after ???1400 h, as indicated by coexistence of hematite with metastable pyrite and elemental sulfur. However, the results confirm that FeIII can be used to trap CO2 in siderite if partly oxidized S, as SO2, is present to reduce the Fe with CO2 in the gas phase. ?? 2005 Elsevier Ltd. All rights reserved.

Creating physically-based three-dimensional microstructures: Bridging phase-field and crystal plasticity models.

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

Lim, Hojun; Owen, Steven J.; Abdeljawad, Fadi F.

In order to better incorporate microstructures in continuum scale models, we use a novel finite element (FE) meshing technique to generate three-dimensional polycrystalline aggregates from a phase field grain growth model of grain microstructures. The proposed meshing technique creates hexahedral FE meshes that capture smooth interfaces between adjacent grains. Three dimensional realizations of grain microstructures from the phase field model are used in crystal plasticity-finite element (CP-FE) simulations of polycrystalline a -iron. We show that the interface conformal meshes significantly reduce artificial stress localizations in voxelated meshes that exhibit the so-called "wedding cake" interfaces. This framework provides a direct linkmore » between two mesoscale models - phase field and crystal plasticity - and for the first time allows mechanics simulations of polycrystalline materials using three-dimensional hexahedral finite element meshes with realistic topological features.« less

Apollo 17 lunar surface cosmic ray experiment - Measurement of heavy solar wind particles

NASA Technical Reports Server (NTRS)

Zinner, E.; Walker, R. M.; Borg, J.; Maurette, M.

1974-01-01

During the Apollo 17 mission a series of metal foils and nuclear track detectors were exposed both in the sun and in the shade on the surface of the moon. Here we give the analysis of the mica detectors which were used to measure the flux of solar wind particles of Fe-group and heavier elements. These particles register as shallow pits after etching in hydrofluoric acid. Calibration experiments were performed to determine the registration properties of different ions and to simulate the lunar environment. We obtain an Fe-group flux of 39,000 per sec per sq cm, which together with the H flux measured on IMP-7 gives an Fe/H ratio of 0.000041. For elements with Z exceeding 45 we can set only an upper limit on the abundance, ruling out an overabundance of extremely heavy elements relative to iron by a factor of 4.

Growth- and substrate-dependent transcription of formate dehydrogenase and hydrogenase coding genes in Syntrophobacter fumaroxidans and Methanospirillum hungatei.

PubMed

Worm, Petra; Stams, Alfons J M; Cheng, Xu; Plugge, Caroline M

2011-01-01

Transcription of genes coding for formate dehydrogenases (fdh genes) and hydrogenases (hyd genes) in Syntrophobacter fumaroxidans and Methanospirillum hungatei was studied following growth under different conditions. Under all conditions tested, all fdh and hyd genes were transcribed. However, transcription levels of the individual genes varied depending on the substrate and growth conditions. Our results strongly suggest that in syntrophically grown S. fumaroxidans cells, the [FeFe]-hydrogenase (encoded by Sfum_844-46), FDH1 (Sfum_2703-06) and Hox (Sfum_2713-16) may confurcate electrons from NADH and ferredoxin to protons and carbon dioxide to produce hydrogen and formate, respectively. Based on bioinformatic analysis, a membrane-integrated energy-converting [NiFe]-hydrogenase (Mhun_1741-46) of M. hungatei might be involved in the energy-dependent reduction of CO(2) to formylmethanofuran. The best candidates for F(420)-dependent N(5),N(10)-methyl-H(4) MPT and N(5),N(10),-methylene-H(4)MPT reduction are the cytoplasmic [NiFe]-hydrogenase and FDH1. 16S rRNA ratios indicate that in one of the triplicate co-cultures of S. fumaroxidans and M. hungatei, less energy was available for S. fumaroxidans. This led to enhanced transcription of genes coding for the Rnf-complex (Sfum_2694-99) and of several fdh and hyd genes. The Rnf-complex probably reoxidized NADH with ferredoxin reduction, followed by ferredoxin oxidation by the induced formate dehydrogenases and hydrogenases.

Selective Tuning of Gilbert Damping in Spin-Valve Trilayer by Insertion of Rare-Earth Nanolayers.

PubMed

Zhang, Wen; Zhang, Dong; Wong, Ping Kwan Johnny; Yuan, Honglei; Jiang, Sheng; van der Laan, Gerrit; Zhai, Ya; Lu, Zuhong

2015-08-12

Selective tuning of the Gilbert damping constant, α, in a NiFe/Cu/FeCo spin-valve trilayer has been achieved by inserting different rare-earth nanolayers adjacent to the ferromagnetic layers. Frequency dependent analysis of the ferromagnetic resonances shows that the initially small magnitude of α in the NiFe and FeCo layers is improved by Tb and Gd insertions to various amounts. Using the element-specific technique of X-ray magnetic circular dichroism, we find that the observed increase in α can be attributed primarily to the orbital moment enhancement of Ni and Co, rather than that of Fe. The amplitude of the enhancement depends on the specific rare-earth element, as well as on the lattice and electronic band structure of the transition metals. Our results demonstrate an effective way for individual control of the magnetization dynamics in the different layers of the spin-valve sandwich structures, which will be important for practical applications in high-frequency spintronic devices.

A Fe-C-Ca big cycle in modern carbon-intensive industries: toward emission reduction and resource utilization

PubMed Central

Sun, Yongqi; Sridhar, Seetharaman; Seetharaman, Seshadri; Wang, Hao; Liu, Lili; Wang, Xidong; Zhang, Zuotai

2016-01-01

Herein a big Fe-C-Ca cycle, clarifying the basic element flows and energy flows in modern carbon-intensive industries including the metallurgical industry and the cement industry, was proposed for the first time in the contexts of emission reduction and iron ore degradation nowadays. This big cycle was focused on three industrial elements of Fe, C and Ca and thus it mainly comprised three interdependent loops, i.e., a C-cycle, a Fe-cycle and a Ca-path. As exemplified, we started from the integrated disposal of hot steel slags, a man-made iron resource via char gasification and the employment of hematite, a natural iron resource greatly extended the application area of this idea. Accordingly, based on this concept, the theoretical potentials for energy saving, emission reduction and Fe resource recovery achieved in modern industry are estimated up to 7.66 Mt of standard coal, 63.9 Mt of CO2 and 25.2 Mt of pig iron, respectively. PMID:26923104

A Fe-C-Ca big cycle in modern carbon-intensive industries: toward emission reduction and resource utilization

NASA Astrophysics Data System (ADS)

Sun, Yongqi; Sridhar, Seetharaman; Seetharaman, Seshadri; Wang, Hao; Liu, Lili; Wang, Xidong; Zhang, Zuotai

2016-02-01

Herein a big Fe-C-Ca cycle, clarifying the basic element flows and energy flows in modern carbon-intensive industries including the metallurgical industry and the cement industry, was proposed for the first time in the contexts of emission reduction and iron ore degradation nowadays. This big cycle was focused on three industrial elements of Fe, C and Ca and thus it mainly comprised three interdependent loops, i.e., a C-cycle, a Fe-cycle and a Ca-path. As exemplified, we started from the integrated disposal of hot steel slags, a man-made iron resource via char gasification and the employment of hematite, a natural iron resource greatly extended the application area of this idea. Accordingly, based on this concept, the theoretical potentials for energy saving, emission reduction and Fe resource recovery achieved in modern industry are estimated up to 7.66 Mt of standard coal, 63.9 Mt of CO2 and 25.2 Mt of pig iron, respectively.

Magnetocaloric effect in heavy rare-earth elements doped Fe-based bulk metallic glasses with tunable Curie temperature

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

Li, Jiawei; Huo, Juntao; Chang, Chuntao, E-mail: ctchang@nimte.ac.cn, E-mail: dujun@nimte.ac.cn

2014-08-14

The effects of heavy rare earth (RE) additions on the Curie temperature (T{sub C}) and magnetocaloric effect of the Fe-RE-B-Nb (RE = Gd, Dy and Ho) bulk metallic glasses were studied. The type of dopping RE element and its concentration can easily tune T{sub C} in a large temperature range of 120 K without significantly decreasing the magnetic entropy change (ΔS{sub M}) and refrigerant capacity (RC) of the alloys. The observed values of ΔS{sub M} and RC of these alloys compare favorably with those of recently reported Fe-based metallic glasses with enhanced RC compared to Gd{sub 5}Ge{sub 1.9}Si{sub 2}Fe{sub 0.1}. The tunable T{submore » C} and large glass-forming ability of these RE doped Fe-based bulk metallic glasses can be used in a wide temperature range with the final required shapes.« less

Iron deficiency cause changes in photochemistry, thylakoid organization, and accumulation of photosystem II proteins in Chlamydomonas reinhardtii.

PubMed

Devadasu, Elsin Raju; Madireddi, Sai Kiran; Nama, Srilatha; Subramanyam, Rajagopal

2016-12-01

A trace element, iron (Fe) plays a pivotal role in photosynthesis process which in turn mediates the plant growth and productivity. Here, we have focused majorly on the photochemistry of photosystem (PS) II, abundance of proteins, and organization of supercomplexes of thylakoids from Fe-depleted cells in Chlamydomonas reinhardtii. Confocal pictures show that the cell's size has been reduced and formed rosette-shaped palmelloids; however, there is no cell death. Further, the PSII photochemistry was reduced remarkably. Further, the photosynthetic efficiency analyzer data revealed that both donor and acceptor side of PSII were equally damaged. Additionally, the room-temperature emission spectra showed the fluorescence emission maxima increased due to impaired energy transfer from PSII to PSI. Furthermore, the protein data reveal that most of the proteins of reaction center and light-harvesting antenna were reduced in Fe-depleted cells. Additionally, the supercomplexes of PSI and PSII were destabilized from thylakoids under Fe-deficient condition showing that Fe is an important element in photosynthesis mechanism.

41 CFR Appendix C to Chapter 301 - Standard Data Elements for Federal Travel [Traveler Identification

Code of Federal Regulations, 2014 CFR

2014-07-01

... education, in scientific, professional, technical, mechanical, trade, clerical, fiscal, administrative, or... Data Elements for Federal Travel [Accounting & Certification] Group name Data elements Description Accounting Classification Accounting Code Agency accounting code. Non-Federal Source Indicator Per Diem...

Structural classification of RAO/sub 3/(MO)/sub n/ compounds (R = Sc, In, Y, or lanthanides; A = Fe(III), Ga, Cr, or Al; M = divalent cation; n = 1-11)

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

Kimizuka, N.; Mohri, T.

A series of new compounds (RAO/sub 3/MO)/sub n/ (n = 1-11) having spinel, YbFe/sub 2/O/sub 4/, or InFeO/sub 3/(ZnO)/sub n/ types of structures were newly synthesized (R = Sc, In, Y, Lu, Yb, Tm, or Er; A = Fe(III), Ga, Cr, or Al; M = Mg, Mn, Fe(II), Co, Ni, Zn, or Cd) at elevated temperatures. The conditions of synthesis and the lattice constants for these compounds are reported. The stacking sequences of the InO/sub 1.5/, (FeZn)O/sub 2.5/, and ZnO layers for InFeO/sub 3/(ZnO)/sub 10/ and the TmO/sub 1.5/, (AlZn)O/sub 2.5/, and ZnO layers for TmAlO/sub 3/(ZnO)/sub 11/ are presented,more » respectively. The crystal structures of the (RAO/sub 3/)/sub m/(MO)/sub n/ phases R = Sc, In, Y, or lanthanide elements; A = Fe(III), Ga, Cr, or Al; M = divalent cation elements; m and n = integer are classified into four crystal structure types (K/sub 2/NiF/sub 4/, CaFe/sub 2/O/sub 4/, YbFe/sub 2/O/sub 4/, and spinel), based upon the constituent cations R, A, and M.« less

Nonlinear static and dynamic finite element analysis of an eccentrically loaded graphite-epoxy beam

NASA Technical Reports Server (NTRS)

Fasanella, Edwin L.; Jackson, Karen E.; Jones, Lisa E.

1991-01-01

The Dynamic Crash Analysis of Structures (DYCAT) and NIKE3D nonlinear finite element codes were used to model the static and implulsive response of an eccentrically loaded graphite-epoxy beam. A 48-ply unidirectional composite beam was tested under an eccentric axial compressive load until failure. This loading configuration was chosen to highlight the capabilities of two finite element codes for modeling a highly nonlinear, large deflection structural problem which has an exact solution. These codes are currently used to perform dynamic analyses of aircraft structures under impact loads to study crashworthiness and energy absorbing capabilities. Both beam and plate element models were developed to compare with the experimental data using the DYCAST and NIKE3D codes.

High-pressure and high-temperature phase diagram for Fe0.9Ni0.1-H alloy

NASA Astrophysics Data System (ADS)

Shibazaki, Yuki; Terasaki, Hidenori; Ohtani, Eiji; Tateyama, Ryuji; Nishida, Keisuke; Funakoshi, Ken-ichi; Higo, Yuji

2014-03-01

Planetary cores are considered to consist of an iron-nickel (Fe-Ni) alloy and light elements and hydrogen is one of plausible light elements in the core. Here we have performed in situ X-ray diffraction experiments on an Fe0.9Ni0.1-H system up to 15.1 GPa and 1673 K, and investigated the effect of Ni on phase relations of FeHx under high pressure and high temperature. The experimental system in the present work was oversaturated with hydrogen. We found a face-center-cubic (fcc) phase (with hydrogen concentration up to x∼1) and a body-center-cubic (bcc) phase (x < 0.1) as stable phases. The partial melting was observed below 6 GPa. We could not observe a double-hexagonal-close-packed (dhcp) phase because of limitations in pressure and temperature conditions. The stability field of each phase of Fe0.9Ni0.1Hx was almost same as that of FeHx. The solidus of Fe0.9Ni0.1Hx was 500-700 K lower than the melting curve of Fe and its liquidus was 400-600 K lower than that of Fe in the pressure range of this study. Both the solidus and liquidus of Fe0.9Ni0.1Hx were depressed at around 3.5 GPa, as was the solidus of FeHx. The hydrogen contents in fcc-Fe0.9Ni0.1Hx just below solidus were slightly lower than those of fcc-FeHx, which suggests that nickel is likely to prevent dissolution of hydrogen into iron. Due to the lower hydrogen solubilities in Fe0.9Ni0.1 compared to Fe, the solidus of Fe0.9Ni0.1Hx is about 100-150 K higher than that of FeHx.

Vibration Response Models of a Stiffened Aluminum Plate Excited by a Shaker

NASA Technical Reports Server (NTRS)

Cabell, Randolph H.

2008-01-01

Numerical models of structural-acoustic interactions are of interest to aircraft designers and the space program. This paper describes a comparison between two energy finite element codes, a statistical energy analysis code, a structural finite element code, and the experimentally measured response of a stiffened aluminum plate excited by a shaker. Different methods for modeling the stiffeners and the power input from the shaker are discussed. The results show that the energy codes (energy finite element and statistical energy analysis) accurately predicted the measured mean square velocity of the plate. In addition, predictions from an energy finite element code had the best spatial correlation with measured velocities. However, predictions from a considerably simpler, single subsystem, statistical energy analysis model also correlated well with the spatial velocity distribution. The results highlight a need for further work to understand the relationship between modeling assumptions and the prediction results.

Micro-spatial variation of elemental distribution in estuarine sediment and their accumulation in mangroves of Indian Sundarban.

PubMed

Bakshi, Madhurima; Ram, S S; Ghosh, Somdeep; Chakraborty, Anindita; Sudarshan, M; Chaudhuri, Punarbasu

2017-05-01

This work describes the micro-spatial variation of elemental distribution in estuarine sediment and bioaccumulation of those elements in different mangrove species of the Indian Sundarbans. The potential ecological risk due to such elemental load on this mangrove-dominated habitat is also discussed. The concentrations of elements in mangrove leaves and sediments were determined using energy-dispersive X-ray fluorescence spectroscopy. Sediment quality and potential ecological risks were assessed from the calculated indices. Our data reflects higher concentration of elements, e.g., Al, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, and Pb, in the sediment, as compared to that reported by earlier workers. Biological concentration factors for K, Ca, Mn, Fe, Cu, and Zn in different mangroves indicated gradual elemental bioaccumulation in leaf tissues (0.002-1.442). Significant variation was observed for elements, e.g., Ni, Mn, and Ca, in the sediments of all the sites, whereas in the plants, significant variation was found for P, S, Cl, K, Ca, Mn, Fe, Cu, and Zn. This was mostly due to the differences in uptake and accumulation potential of the plants. Various sediment quality indices suggested the surface sediments to be moderately contaminated and suffering from progressive deterioration. Cu, Cr, Zn, Mn, and Ni showed higher enrichment factors (0.658-1.469), contamination factors (1.02-2.7), and geo-accumulation index (0.043-0.846) values. The potential ecological risk index values considering Cu, Cr, Pb, and Zn were found to be within "low ecological risk" category (20.04-24.01). However, Cr and Ni in the Sundarban mangroves exceeded the effect range low and probable effect level limits. Strong correlation of Zn with Fe and K was observed, reflecting their similar transportation and accumulation process in both sediment and plant systems. The plant-sediment elemental correlation was found to be highly non-linear, suggesting role of some physiological and edaphic factors in the accumulation process. Overall, the study of micro-spatial distribution of elements can act as a useful tool for determining health of estuarine ecosystem.

Constraints on Galactic Cosmic-Ray Origins from Elemental and Isotopic Composition Measurements

NASA Technical Reports Server (NTRS)

Binns, W. R.; Christian, E. R.; Cummings, A. C.; deNolfo, G. A.; Israel, M. H.; Leske, R. A.; Mewaldt, R. A,; Stone, E. C.; vonRosevinge, T. T.; Wiedenbeck, M. E.

2013-01-01

The most recent measurements by the Cosmic Ray Isotope Spectrometer (CRIS) aboard the Advanced Composition Explorer (ACE) satellite of ultra-heavy cosmic ray isotopic and elemental abundances will be presented. A range of isotope and element ratios, most importantly Ne-22/Ne-20, Fe-58/Fe-56, and Ga-31/Ge -32 show that the composition is consistent with source material that is a mix of approx 80% ISM (with Solar System abundances) and 20% outflow/ejecta from massive stars. In addition, our data show that the ordering of refractory and volatile elements with atomic mass is greatly improved when compared to an approx 80%/20% mix rather than pure ISM, that the refractory and volatile elements have similar slopes, and that refractory elements are preferentially accelerated by a factor of approx 4. We conclude that these data are consistent with an OB association origin of GCRs.

Effect of strain and diet on growth performance characteristics and relative expression of genes coding for electron transport chain in channel catfish

USDA-ARS?s Scientific Manuscript database

The major cost in aquaculture production systems is feed, and the use of biotechnology approaches to identify fishes with superior feed efficiency (FE) may have a positive influence on profitability. There been little use of genetically based technologies to assess FE in culture fishes. Mitochondria...

Iron Sulfide Attenuates the Methanogenic Toxicity of Elemental Copper and Zinc Oxide Nanoparticles and their Soluble Metal Ion Analogs

PubMed Central

Gonzalez-Estrella, Jorge; Gallagher, Sara; Sierra-Alvarez, Reyes; Field, Jim A.

2016-01-01

Elemental copper (Cu0) and zinc oxide (ZnO) nanoparticle (NP) toxicity to methanogens has been attributed to the release of soluble metal ions. Iron sulfide (FeS) partially controls the soluble concentration of heavy metals and their toxicity in aquatic environments. Heavy metals displace the Fe from FeS forming poorly soluble metal sulfides in the FeS matrix. Therefore, FeS may be expected to attenuate the NP toxicity. This work assessed FeS as an attenuator of the methanogenic toxicity of Cu0 and ZnO NPs and their soluble salt analogs. The toxicity attenuation capacity of fine (25–75 µm) and coarse (500 to 1200 µm) preparations of FeS (FeS-f and FeS-c respectively) was tested in the presence of highly inhibitory concentrations of CuCl2, ZnCl2 Cu0 and ZnO NPs. FeS-f attenuated methanogenic toxicity better than FeS-c. The results revealed that 2.5× less FeS-f than FeS-c was required to recover the methanogenic activity to 50% (activity normalized to uninhibited controls). The results also indicated that a molar FeS-f/Cu0 NP, FeS-f/ZnO NP, FeS-f/ZnCl2, and FeS-f/CuCl2 ratio of 2.14, 2.14, 4.28, and 8.56 respectively, was necessary to recover the methanogenic activity to >75%. Displacement experiments demonstrated that CuCl2 and ZnCl2 partially displaced Fe from FeS. As a whole, the results indicate that not all the sulfide in FeS was readily available to react with the soluble Cu and Zn ions which may explain the need for a large stoichiometric excesses of FeS to highly attenuate Cu and Zn toxicity. Overall, this study provides evidence that FeS attenuates the toxicity caused by Cu0 and ZnO NPs and their soluble ion analogs to methanogens. PMID:26803736

The Oxidation State of Fe in Glasses from the Galapagos Archipelago: Variable Oxygen Fugacity as a Function of Mantle Source

NASA Astrophysics Data System (ADS)

Peterson, M. E.; Kelley, K. A.; Cottrell, E.; Saal, A. E.; Kurz, M. D.

2015-12-01

The oxidation state of the mantle plays an intrinsic role in the magmatic evolution of the Earth. Here we present new μ-XANES measurements of Fe3+/ΣFe ratios (a proxy for ƒO2) in a suite of submarine glasses from the Galapagos Archipelago. Using previously presented major, trace, and volatile elements and isotopic data for 4 groups of glass that come from distinct mantle sources (depleted upper mantle, 2 recycled, and a primitive mantle source) we show that Fe3+/ΣFe ratios vary both with the influence of shallow level processes and with variations in mantle source. Fe3+/ΣFe ratios increase with differentiation (i.e. decreasing MgO), but show a large variation at a given MgO. Progressive degassing of sulfur accompanies decreasing Fe3+/ΣFe ratios, while assimilation of hydrothermally altered crust (as indicated by increasing Sr/Sr*) is shown to increase Fe3+/ΣFe ratios. After taking these processes into account, there is still variability in the Fe3+/ΣFe ratios of the isotopically distinct sample suites studied, yielding a magmatic ƒO2 that ranges from ΔQFM = +0.16 to +0.74 (error < 0.5 log units) and showing that oxidation state varies as a function of mantle source composition in the Galapagos hotspot system. After correcting back to a common MgO content = 8.0 wt%, the trace element depleted group similar to MORB (ITD), and the group similar to Pinta (WD = high Th/La, Δ7/4, Δ8/4 ratios) show Fe3+/ΣFe ratios within the range of MORB (average ITD = 0.162 ± 0.003 and WD = 0.164 ± 0.006). Another trace element enriched group similar to Sierra Negra and Cerro Azul (ITE = enriched Sr and Pb isotopes) shows evidence of mixing between oxidized and reduced sources (ITE oxidized end-member = 0.177). This suggests that mantle sources in the Galapagos that are thought to contain recycled components (i.e., WD and ITE groups) have distinct oxidation states. The high 3He/4He Fernandina samples (HHe group) are shown to be the most oxidized (ave. 0.175 ± 0.006). With C/3He ratios an order of magnitude greater than MORB this suggests that the primitive mantle is a more carbonated and oxidized source than the depleted upper mantle.

Recombinant Escherichia coli as a biofactory for various single- and multi-element nanomaterials.

PubMed

Choi, Yoojin; Park, Tae Jung; Lee, Doh C; Lee, Sang Yup

2018-06-05

Nanomaterials (NMs) are mostly synthesized by chemical and physical methods, but biological synthesis is also receiving great attention. However, the mechanisms for biological producibility of NMs, crystalline versus amorphous, are not yet understood. Here we report biosynthesis of 60 different NMs by employing a recombinant Escherichia coli strain coexpressing metallothionein, a metal-binding protein, and phytochelatin synthase that synthesizes a metal-binding peptide phytochelatin. Both an in vivo method employing live cells and an in vitro method employing the cell extract are used to synthesize NMs. The periodic table is scanned to select 35 suitable elements, followed by biosynthesis of their NMs. Nine crystalline single-elements of Mn 3 O 4 , Fe 3 O 4 , Cu 2 O, Mo, Ag, In(OH) 3 , SnO 2 , Te, and Au are synthesized, while the other 16 elements result in biosynthesis of amorphous NMs or no NM synthesis. Producibility and crystallinity of the NMs are analyzed using a Pourbaix diagram that predicts the stable chemical species of each element for NM biosynthesis by varying reduction potential and pH. Based on the analyses, the initial pH of reactions is changed from 6.5 to 7.5, resulting in biosynthesis of various crystalline NMs of those previously amorphous or not-synthesized ones. This strategy is extended to biosynthesize multi-element NMs including CoFe 2 O 4 , NiFe 2 O 4 , ZnMn 2 O 4 , ZnFe 2 O 4 , Ag 2 S, Ag 2 TeO 3 , Ag 2 WO 4 , Hg 3 TeO 6 , PbMoO 4, PbWO 4 , and Pb 5 (VO 4 ) 3 OH NMs. The strategy described here allows biosynthesis of NMs with various properties, providing a platform for manufacturing various NMs in an environmentally friendly manner.

Bhasmas: unique ayurvedic metallic-herbal preparations, chemical characterization.

PubMed

Kumar, A; Nair, A G C; Reddy, A V R; Garg, A N

2006-03-01

Bhasmas are unique Ayurvedic metallic preparations with herbal juices/fruits, known in the Indian subcontinent since the seventh century BC and widely recommended for treatment of a variety of chronic ailments. Twenty bhasmas based on calcium, iron, zinc, mercury, silver, potassium, arsenic, copper, tin, and gemstones were analyzed for up to 18 elements by instrumental neutron activation analysis, including their C, H, N, and S contents. In addition to the major constituent element found at % level, several other essential elements such as Na, K, Ca, Mg, V, Mn, Fe, Cu, and Zn have also been found in microg/g amounts and ultratrace (ng/g) amounts of Au and Co. These seem to remain chelated with organic ligands derived from medicinal herbs. The bhasmas are biologically produced nanoparticles and are taken along with milk, butter, honey, or ghee (a preparation from milk); thus, this makes these elements easily assimilable, eliminating their harmful effects and enhancing their biocompatibility. Siddha Makaradhwaja, a mercury preparation is found to be stoichiometrically HgS without any traces of any other element. Similarly, Swet Parpati is stoichiometrically KNO3 but is found to have Mn, Cu, Zn, Na, P, and Cl as well. An attempt has been made to correlate the metallic contents with their medicinal importance. Na and K, the two electrolytic elements, seem to be well correlated, although K/Na varies in a wide range from 0.06 to 95, with specifically low values for Ca-, Fe-, and Zn-based bhasmas. K/P also varies in a wide range from 0.23 to 12, although for most bhasmas (n = 12), it is 2.3 +/- 1.2. Further, Fe/Mn is linearly correlated (r = 0.96) with Fe in nine noniron bhasmas.

[Contents of nutrient elements in NH4(+)-N fertilizer and urea].

PubMed

Wang, Zheng-Rui; Qu, Gui-Qin; Rui, Yu-Kui; Shen, Jian-Bo; Zhang, Fu-Suo

2009-03-01

Fertilizer contains not only one compound or one element, so it is important to determine the contents of other elements necessitous and beneficial to plant. All the other nutrient elements for plant, including necessitous elements and beneficial elements in ammonia nitrogen fertilizer ((NH4)2SO4) and CO(NH2)2, were analyzed by method of ICP-MS. The results showed that ammonia nitrogen fertilizer ((NH4)2SO4) and CO(NH2)2 both contain many necessitous elements, Mg, P, K, Ca, Mn, Fe, Ni, Cu, Zn and Mo, thereinto the contents of Mg, P, K, Ca, Mn and Fe were on microg x g(-1) the level, and Ni, Cu, Zn and Mo were on the ng x g(-1) level; compared with CO(NH2)2, ammonia nitrogen fertilizer ((NH4)2SO4) contains more necessitous elements and beneficial elements except Mo and Si. All the above elements could influence the results of nitrogen fertilizer efficiency experiments, so pure fertilizer should be used in the future nitrogen fertilizer efficiency experiments and the comparative experiments of different form nitrogen fertilizer.

The Diverse Origins of Neutron-capture Elements in the Metal-poor Star HD 94028: Possible Detection of Products of I-Process Nucleosynthesis

NASA Astrophysics Data System (ADS)

Roederer, Ian U.; Karakas, Amanda I.; Pignatari, Marco; Herwig, Falk

2016-04-01

We present a detailed analysis of the composition and nucleosynthetic origins of the heavy elements in the metal-poor ([Fe/H] = -1.62 ± 0.09) star HD 94028. Previous studies revealed that this star is mildly enhanced in elements produced by the slow neutron-capture process (s process; e.g., [Pb/Fe] = +0.79 ± 0.32) and rapid neutron-capture process (r process; e.g., [Eu/Fe] = +0.22 ± 0.12), including unusually large molybdenum ([Mo/Fe] = +0.97 ± 0.16) and ruthenium ([Ru/Fe] = +0.69 ± 0.17) enhancements. However, this star is not enhanced in carbon ([C/Fe] = -0.06 ± 0.19). We analyze an archival near-ultraviolet spectrum of HD 94028, collected using the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope, and other archival optical spectra collected from ground-based telescopes. We report abundances or upper limits derived from 64 species of 56 elements. We compare these observations with s-process yields from low-metallicity AGB evolution and nucleosynthesis models. No combination of s- and r-process patterns can adequately reproduce the observed abundances, including the super-solar [As/Ge] ratio (+0.99 ± 0.23) and the enhanced [Mo/Fe] and [Ru/Fe] ratios. We can fit these features when including an additional contribution from the intermediate neutron-capture process (I process), which perhaps operated through the ingestion of H in He-burning convective regions in massive stars, super-AGB stars, or low-mass AGB stars. Currently, only the I process appears capable of consistently producing the super-solar [As/Ge] ratios and ratios among neighboring heavy elements found in HD 94028. Other metal-poor stars also show enhanced [As/Ge] ratios, hinting that operation of the I process may have been common in the early Galaxy. These data are associated with Program 072.B-0585(A), PI. Silva. Some data presented in this paper were obtained from the Barbara A. Mikulski Archive for Space Telescopes (MAST). The Space Telescope Science Institute is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. These data are associated with Programs GO-7402 and GO-8197. This work is based on data obtained from the European Southern Observatory (ESO) Science Archive Facility. These data are associated with Program 072.B-0585(A). This paper includes data taken at The McDonald Observatory of The University of Texas at Austin.

PM2.5 water-soluble elements in the southeastern United States: automated analytical method development, spatiotemporal distributions, source apportionment, and implications for heath studies

NASA Astrophysics Data System (ADS)

Fang, T.; Guo, H.; Verma, V.; Peltier, R. E.; Weber, R. J.

2015-06-01

Water-soluble redox-active metals are potentially toxic due to the ability to catalytically generate reactive oxygen species (ROS) in vivo, leading to oxidative stress. As part of the Southeastern Center for Air Pollution and Epidemiology (SCAPE), we developed a method to quantify water-soluble elements, including redox-active metals, from a large number of filter samples (N = 530) in support of the Center's health studies. PM2.5 samples were collected during 2012-2013 at various sites (three urban, two rural, a near-road, and a road-side site) in the southeastern US, using high-volume samplers. Water-soluble elements (S, K, Ca, Ti, Mn, Fe, Cu, Zn, As, Se, Br, Sr, Ba, and Pb) were determined by extracting filters in deionized water and re-aerosolized for analyses by X-ray fluorescence (XRF) using an online aerosol element analyzer (Xact, Cooper Environmental). Concentrations ranged from detection limits (nominally 0.1 to 30 ng m-3) to 1.2 μg m-3, with S as the most abundant element, followed by Ca, K, Fe, Cu, Zn, and Ba. Positive Matrix Factorization (PMF) identified four factors that were associated with specific sources based on relative loadings of various tracers. These include: brake/tire wear (with tracers Ba and Cu); biomass burning (K); secondary formation (S, Se, and WSOC); and mineral dust (Ca). Of the four potentially toxic and relatively abundant metals (redox active Cu, Mn, Fe, and redox-inactive Zn), 51 % of Cu, 32 % of Fe, 17 % of Mn, and 45 % of Zn, were associated with the brake/tire factor. Mn was mostly associated with the mineral dust factor (45 %). These two factors were higher in warm (dryer) periods that favored particle re-suspension. Zn was found in a mixture of factors, with 26 % associated with mineral dust, 14 % biomass burning, and 13 % secondary formation. Roughly 50 % of Fe and 40 % of Cu was apportioned to the secondary formation factor, likely through increased solubility by sulfur-driven aerosol acidity. Linkages between sulfate and water-soluble Fe and Cu may account for some of the past observed associations between sulfate/sulfur oxide and health outcomes. For Cu, Mn, Fe, and Zn, only Fe was correlated with PM2.5 mass (r = 0.73-0.80). Overall, mobile source emissions generated through mechanical processes (re-entrained road dust, tire and break wear) and processing by secondary sulfate were major contributors to water-soluble metals known to be capable of generating ROS.

Dissolved and Colloidal Trace Elements in the Mississippi River Delta Outflow after Hurricanes Katrina and Rita

NASA Astrophysics Data System (ADS)

Shim, M.; Swarzenski, P. W.; Shiller, A. M.

2010-12-01

The Mississippi River (MR) plays an important role as a major fluvial source of dissolved and particulate materials for the Gulf of Mexico (GOM). This region is periodically disturbed by tropical weather systems including major hurricanes. Such storms have the potential to stir up the normally stratified water column of the Louisiana Shelf and thus can serve as a mechanism for the abrupt termination of seasonal bottom water hypoxia. Additionally, strong tropical systems can cause the resuspension of shelf bottom sediments which could result in the injection of trace elements into the water column. In the summer of 2005, two major hurricanes, Katrina and Rita, passed over the Louisiana Shelf within a month of each other. Three weeks after Rita, we participated in a survey of the waters of the Mississippi River delta outflow, examining the distributions of trace elements (including Ba, Co, Cr, Cs, Cu, Fe, Mn, Ni, Re, U, V, and Zn) in a comparison with previous results in this area. We indeed observed that there was limited stratification on the shelf and that bottom waters were no longer hypoxic. This resulted, for instance, in bottom water dissolved Mn being lower than is typically observed during hypoxia, but with concentrations still compatible with Mn-O2 trends previously reported. Interestingly, for no element were we able to identify an obvious effect of sediment resuspension on its distribution. In general, elemental distributions were compatible with previous observations in the Mississippi outflow system. Co and Re, which have not been reported for this system previously, showed behavior consistent with other systems: input for Co likely from desorption and conservative mixing for Re. For Cs, an element for which there is little information regarding its estuarine behavior, conservative mixing was also observed. Our filtration method, which allowed us to distinguish the dissolved (<0.02 µm) from colloidal (0.02 - 0.45 µm) phase, revealed significant colloidal fractions for Fe and Zn, only. For Fe, the colloidal phase was the dominant fraction and was rapidly removed at low salinity. Dissolved Fe, in contrast, persisted out to mid-salinities, being removed in a similar fashion to nitrate. This ability to distinguish the smaller Fe (likely dominantly organically complexed) from larger colloidal suspensates may be useful in better interpreting the bioavailablity of the Fe in estuarine systems.

Metal transports and enrichments in iron depositions hosted in basaltic rocks. II: Metal rich fluids and Fe origin

NASA Astrophysics Data System (ADS)

Zhang, Ronghua; Zhang, Xuetong; Hu, Shumin

2015-12-01

This study focuses on revealing the mechanism of metal transport, enrichment and Fe origin of iron deposition during water basalt interactions occurred in basaltic rocks. Observations of the iron deposits (anhydrite-magnetite-pyroxene type deposits) hosted in K-rich basaltic rocks in the Mesozoic volcanic area of the Middle-Lower Yangtze River valley, China, indicate that the mechanism of metal transport and enrichment for those deposits are significant objective to scientists, and the Fe origin problem is not well resolved. Here the metal transport, enrichment and iron origin have been investigated in high temperature experiments of water basaltic interactions. These deposits were accompanying a wide zone with metal alteration. The effects of hydrothermal alteration on major rock-forming element concentrations in basaltic rock were investigated by systematically comparing the chemical compositions of altered rocks with those of fresh rocks. In the deposits, these metals are distributed throughout altered rocks that exhibit vertical zoning from the deeper to the shallow. Then, combined with the investigations of the metal-alterations, we performed kinetic experiments of water-basaltic rock interactions using flow-through reactors in open systems at temperatures from 20 °C to 550 °C, 23-34 MPa. Release rates for the rock-forming elements from the rocks have been measured. Experiments provide the release rates for various elements at a large temperature range, and indicate that the dissolution rates (release rates) for various elements vary with temperature. Si, Al, and K have high release rates at temperatures from 300 °C to 500 °C; the maximum release rates (RMX) for Si are reached at temperatures from 300 °C to 400 °C. The RMXs for Ca, Mg, and Fe are at low temperatures from 20 °C to 300 °C. Results demonstrate that Fe is not released from 400 °C to 550 °C, and indicate that when deep circling fluids passed through basaltic rocks, Fe was not mobile, and fixed in the rocks at temperatures from 400 °C to 550 °C. Significance of the results is to provide evidence that the Fe of ores originated from basalt, and Fe-oxides precipitated across the critical state of water. Simultaneously, Ca, Mg and Fe are fixed in the deeper altered rocks (mafic minerals). But, Fe was dissolved at relatively low temperatures (100-300 °C). Si, Al, and K were easily mobile from basalt by upward flowing fluids from 300 °C to 400 °C and transported to the upper part (silicified and argillized rock).

Evaluation of the finite element fuel rod analysis code (FRANCO)

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

Lee, K.; Feltus, M.A.

1994-12-31

Knowledge of temperature distribution in a nuclear fuel rod is required to predict the behavior of fuel elements during operating conditions. The thermal and mechanical properties and performance characteristics are strongly dependent on the temperature, which can vary greatly inside the fuel rod. A detailed model of fuel rod behavior can be described by various numerical methods, including the finite element approach. The finite element method has been successfully used in many engineering applications, including nuclear piping and reactor component analysis. However, fuel pin analysis has traditionally been carried out with finite difference codes, with the exception of Electric Powermore » Research Institute`s FREY code, which was developed for mainframe execution. This report describes FRANCO, a finite element fuel rod analysis code capable of computing temperature disrtibution and mechanical deformation of a single light water reactor fuel rod.« less

45 CFR 162.103 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-10-01

... definitions apply: Code set means any set of codes used to encode data elements, such as tables of terms... code sets inherent to a transaction, and not related to the format of the transaction. Data elements... information in a transaction. Data set means a semantically meaningful unit of information exchanged between...

45 CFR 162.103 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-10-01

... definitions apply: Code set means any set of codes used to encode data elements, such as tables of terms... code sets inherent to a transaction, and not related to the format of the transaction. Data elements... information in a transaction. Data set means a semantically meaningful unit of information exchanged between...

Seasonal variations in C:N:Si:Ca:P:Mg:S:K:Fe relationships of seston from Norwegian coastal water: Impact of extreme offshore forcing during winter-spring 2010.

PubMed

Erga, Svein Rune; Haugen, Stig Bjarte; Bratbak, Gunnar; Egge, Jorun Karin; Heldal, Mikal; Mork, Kjell Arne; Norland, Svein

2017-11-20

The aim of this study was to reveal the relative content of C, N, Ca, Si, P, Mg, K, S and Fe in seston particles in Norwegian coastal water (NCW), and how it relates to biological and hydrographic processes during seasonal cycles from October 2009-March 2012. The following over all stoichiometric relationship for the time series was obtained: C 66 N 11 Si 3.4 Ca 2.3 P 1 Mg 0.73 S 0.37 K 0.35 Fe 0.30 , which is novel for marine waters. A record-breaking (187-year record) negative North Atlantic Oscillation (NAO) index caused extreme physical forcing on the Norwegian Coastal Current Water (NCCW) during the winter 2009-2010, and the inflow and upwelling of saline Atlantic water (AW) in the fjord was thus extraordinary during late spring-early summer in 2010. The element concentrations in fjord seston particles responded strongly to this convection, revealed by maximum values of all elements, except Fe, exceeding average values with 10.8 × for Ca, 9.3 for K, 5.3 for S, 5.1 for Mg, 4.6 for Si, 4.0 for P, 3.8 for C, and 3.3 for N and Fe. This indicates that the signature of the Atlantic inflow was roughly two times stronger for Ca and K than for the others, probably connected with peaks in coccolithophorids and diatoms. There is, however, 1.5 × more of Si than Ca contained in the seston, which could be due to a stronger dominance of diatoms than coccolithophorids, confirming their environmental fitness. In total our data do not indicate any severe nutrient limitation with respect to N, P and Fe, but accumulation of iron by Fe-sequestering bacteria might at times reduce the availability of the dissolved Fe-fraction. There is a high correlation between most of the measured elements, except for Ca, which together with Fe only weakly correlated with the other elements. It is to be expected that environmental alterations in NCW related to climate change will influence the seston elemental composition, but the full effect of this will be strongly dependent on the future dominance of the high pressure versus low pressure systems (i.e. NAO index), since they are key regulators for the direction of wind driven vertical convection (i.e. upwelling or downwelling). Changes in stratification, temperature, light, pH (ocean acidification), CaCO 3 concentrations (carbon pump) and availability of nutrients in the euphotic zone (biogeochemical cycling) are essential for the future dominance of coccolithophorids versus diatoms.

Laser properties of Fe2+:ZnSe fabricated by solid-state diffusion bonding

NASA Astrophysics Data System (ADS)

Balabanov, S. S.; Firsov, K. N.; Gavrishchuk, E. M.; Ikonnikov, V. B.; Kazantsev, S. Yu; Kononov, I. G.; Kotereva, T. V.; Savin, D. V.; Timofeeva, N. A.

2018-04-01

The characteristics of an Fe2+:ZnSe laser at room temperature and its active elements with undoped faces were studied. Polycrystalline elements with one or two diffusion-doped internal layers were obtained by the solid-state diffusion bonding technique applied to chemical vapor deposition grown ZnSe plates preliminary doped with Fe2+ ions in the process of hot isostatic pressing. A non-chain electric-discharge HF laser was used to pump the crystals. It was demonstrated that increasing the number of doped layers allows increasing the maximum diameter of the pump radiation spot and the pump energy without the appearance of transversal parasitic oscillation. For the two-layer-doped active element with a diameter of 20 mm an output energy of 480 mJ was achieved with 37% total efficiency with respect to the absorbed energy. The obtained results demonstrate the potential of the developed technology for fabrication of active elements by the solid-state diffusion bonding technique combined with the hot isostatic pressing treatment for efficient IR lasers based on chalcogenides doped with transition metal ions.

Urban and industrial contribution to trace elements in the atmosphere as measured in holm oak bark

NASA Astrophysics Data System (ADS)

Drava, Giuliana; Brignole, Daniele; Giordani, Paolo; Minganti, Vincenzo

2016-11-01

The concentrations of As, Cd, Co, Cu, Fe, Mn, Ni, Pb, V and Zn were measured by ICP-OES in samples of bark of the holm oak (Quercus ilex L.) collected from trees in different urban environments (residential and mixed residential/industrial). The use of tree bark as a bioindicator makes it easy to create maps that can provide detailed data on the levels and on the spatial distribution of each trace element. For most of the elements considered (As, Co, Fe, Mn, Ni, V and Zn), the concentrations in the industrial sites are about twice (from 1.9 to 2.8 times higher) of those in the residential area. Arsenic, Fe and Zn show the highest concentrations near a steel plant (operational until 2005), but for the other elements it is not possible to identify any localized source, as evident from the maps. In areas where urban pollution is summed up by the impact of industrial activities, the population is exposed to significantly higher amounts of some metals than people living in residential areas.

Fungal Transformation of Tree Stumps into a Suitable Resource for Xylophagous Beetles via Changes in Elemental Ratios

PubMed Central

Filipiak, Michał; Sobczyk, Łukasz; Weiner, January

2016-01-01

The elements present in dead pine stumps inhabited by larvae of wood-boring beetles (Stictoleptura rubra, Arhopalus rusticus and Chalcophora mariana) were analyzed over the initial (first 5 years; a chronosequence) stages of wood decay. The quantities of N, P, K, Ca, Mg, Fe, Zn, Mn, Cu and Na (but not S) increased with increases in the content of ergosterol (used as a proxy for the amount of fungal tissue). In fact, the amounts of P, N, K, Fe and Cu presented marked increases. These findings show that fungi stoichiometrically rearrange dead wood by importing externally occurring nutrients to decaying stumps. During the first years of wood decay, the ratios of C to other elements decrease substantially, but differently, for various elements, whereas the N:Fe, N:Cu, N:P and N:K ratios remain relatively stable. Therefore, the stoichiometric mismatch between xylophages and their food is greatly reduced. By changing the nutritional stoichiometry of dead wood, fungi create a nutritional niche for wood-eaters, and these changes enable the development of xylophages.

Frequency response function (FRF) based updating of a laser spot welded structure

NASA Astrophysics Data System (ADS)

Zin, M. S. Mohd; Rani, M. N. Abdul; Yunus, M. A.; Sani, M. S. M.; Wan Iskandar Mirza, W. I. I.; Mat Isa, A. A.

2018-04-01

The objective of this paper is to present frequency response function (FRF) based updating as a method for matching the finite element (FE) model of a laser spot welded structure with a physical test structure. The FE model of the welded structure was developed using CQUAD4 and CWELD element connectors, and NASTRAN was used to calculate the natural frequencies, mode shapes and FRF. Minimization of the discrepancies between the finite element and experimental FRFs was carried out using the exceptional numerical capability of NASTRAN Sol 200. The experimental work was performed under free-free boundary conditions using LMS SCADAS. Avast improvement in the finite element FRF was achieved using the frequency response function (FRF) based updating with two different objective functions proposed.

High density submicron magnetoresistive random access memory (invited)

NASA Astrophysics Data System (ADS)

Tehrani, S.; Chen, E.; Durlam, M.; DeHerrera, M.; Slaughter, J. M.; Shi, J.; Kerszykowski, G.

1999-04-01

Various giant magnetoresistance material structures were patterned and studied for their potential as memory elements. The preferred memory element, based on pseudo-spin valve structures, was designed with two magnetic stacks (NiFeCo/CoFe) of different thickness with Cu as an interlayer. The difference in thickness results in dissimilar switching fields due to the shape anisotropy at deep submicron dimensions. It was found that a lower switching current can be achieved when the bits have a word line that wraps around the bit 1.5 times. Submicron memory elements integrated with complementary metal-oxide-semiconductor (CMOS) transistors maintained their characteristics and no degradation to the CMOS devices was observed. Selectivity between memory elements in high-density arrays was demonstrated.

METAL-POOR STARS OBSERVED WITH THE MAGELLAN TELESCOPE. I. CONSTRAINTS ON PROGENITOR MASS AND METALLICITY OF AGB STARS UNDERGOING s-PROCESS NUCLEOSYNTHESIS

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

Placco, Vinicius M.; Rossi, Silvia; Frebel, Anna

2013-06-20

We present a comprehensive abundance analysis of two newly discovered carbon-enhanced metal-poor (CEMP) stars. HE 2138-3336 is a s-process-rich star with [Fe/H] = -2.79, and has the highest [Pb/Fe] abundance ratio measured thus far, if non-local thermodynamic equilibrium corrections are included ([Pb/Fe] = +3.84). HE 2258-6358, with [Fe/H] = -2.67, exhibits enrichments in both s- and r-process elements. These stars were selected from a sample of candidate metal-poor stars from the Hamburg/ESO objective-prism survey, and followed up with medium-resolution (R {approx} 2000) spectroscopy with GEMINI/GMOS. We report here on derived abundances (or limits) for a total of 34 elements inmore » each star, based on high-resolution (R {approx} 30, 000) spectroscopy obtained with Magellan-Clay/MIKE. Our results are compared to predictions from new theoretical asymptotic giant branch (AGB) nucleosynthesis models of 1.3 M{sub Sun} with [Fe/H] = -2.5 and -2.8, as well as to a set of AGB models of 1.0 to 6.0 M{sub Sun} at [Fe/H] = -2.3. The agreement with the model predictions suggests that the neutron-capture material in HE 2138-3336 originated from mass transfer from a binary companion star that previously went through the AGB phase, whereas for HE 2258-6358, an additional process has to be taken into account to explain its abundance pattern. We find that a narrow range of progenitor masses (1.0 {<=} M(M{sub Sun }) {<=} 1.3) and metallicities (-2.8 {<=} [Fe/H] {<=}-2.5) yield the best agreement with our observed elemental abundance patterns.« less

Synthesis of Ti Oxides at Reducing Conditions: Implications for Beamline Standards and Cosmochemistry

NASA Technical Reports Server (NTRS)

Righter, K.; Pando, K. A.; Butterworth, A. L.; Gainsforth, Z.; Jilly-Rehak, C. E.; Westphal, A. J.

2017-01-01

These initial experiments demonstrate the great potential for synthesizing customized compounds for use as standards, or in buffering experiments at reducing conditions. We are also investigating Cr and V oxides, as well as compounds containing these elements such as FeV2O4 and FeCr2O4. Oxygen fugacity exerts a major control on mineral major element chemistry and elemental valence of minerals in any plane-tary compositional system [1]. For Earth, Fe is multivalent ranging from nearly Fe0 at low fO2 in the deep mantle to Fe2+ to Fe3+ at high low fO2. For solar nebular and meteoritic materials fO2 ranges from near IW to 10 log fO2 units below the IW buffer [1]. Phases in CAIs, for example, contain no Fe2+, but may contain Ti4+, Ti3+, or Ti2+, and Cr3+ or Cr2+, and V3+ or V2+ [1,2,3]. De-tailed study of inclusions may reveal important differences in fO2 thus reflecting different environments in the solar nebula [4]. XANES, FEG-SEM, and TEM can reveal such variations in micro and nano samples such as Stardust and cosmic dust particles [5], but successful application to reduced conditions depends upon the availability of well characterized standards. Acquiring appropriate standards for reduced phases that contain Ti3+ or Ti2+, Cr3+ or Cr2+, and V3+ or V2+ can be a challenge. Here we report our preliminary results at synthesizing reduced Ti bearing standards, and focus on the preliminary characterization.

Diffusion-driven magnesium and iron isotope fractionation at a gabbro-granite boundary

NASA Astrophysics Data System (ADS)

Wu, Hongjie; He, Yongsheng; Teng, Fang-Zhen; Ke, Shan; Hou, Zhenhui; Li, Shuguang

2018-02-01

Significant magnesium and iron isotope fractionations were observed in an adjacent gabbro and granite profile from the Dabie Orogen, China. Chilled margin and granitic veins at the gabbro side and gabbro xenoliths in the granite indicate the two intrusions were emplaced simultaneously. The δ26Mg decreases from -0.28 ± 0.04‰ to -0.63 ± 0.08‰ and δ56Fe increases from -0.07 ± 0.03‰ to +0.25 ± 0.03‰ along a ∼16 cm traverse from the contact to the granite. Concentrations of major elements such as Al, Na, Ti and most trace elements also systematically change with distance to the contact. All the observations suggest that weathering, magma mixing, fluid exsolution, fractional crystallization and thermal diffusion are not the major processes responsible for the observed elemental and isotopic variations. Rather, the negatively correlated Mg and Fe isotopic compositions as well as co-variations of Mg and Fe isotopes with Mg# reflect Mg-Fe inter-diffusion driven isotope fractionation, with Mg diffusing from the chilled gabbro into the granitic melt and Fe oppositely. The diffusion modeling yields a characteristic diffusive transport distance of ∼6 cm. Consequently, the diffusion duration, during which the granite may have maintained a molten state, can be constrained to ∼2 My. The cooling rate of the granite is calculated to be 52-107 °C/My. Our study suggests diffusion profiles can be a powerful geospeedometry. The observed isotope fractionations also indicate that Mg-Fe inter-diffusion can produce large stable isotope fractionations at least on a decimeter scale, with implications for Mg and Fe isotope study of mantle xenoliths, mafic dikes, and inter-bedded lavas.

Migration laws of major elements of Laowashan bauxite in Zunyi area, northern Guizhou province of China

NASA Astrophysics Data System (ADS)

Cui, Tao

2018-01-01

After exploring migration laws of major elements in Laowashan bauxite of northern Guizhou Province by geochemical methods, it was found that: 1) Si was negatively correlated to Al and Ti; Al showed significant negative correlations with Si and Fe; Al was positively correlated to Ti. 2) The content of Si and Fe was low in the middle part, high at the top and the highest at the bottom. The content of Al and Ti is the highest in the middle, followed by the content at the top and the bottom successively. 3) Karst depressions are favorable for groundwater discharge through leaching, leading to heavy loss of Fe in ZK-CS1.

An Overview of the Effects of Alloying Elements on the Properties of Lightweight Fe-(15-35) Mn-(5-12) Al-(0.3-1.2) C Steel

NASA Astrophysics Data System (ADS)

Xing, Jia; Wei, Yinghui; Hou, Lifeng

2018-06-01

In this review, the influences of alloying elements on the phase constitution, density, and stacking fault energy of Fe-(15-35) Mn-(5-12) Al-(0.3-1.2) C lightweight steel are discussed. The mechanical properties of austenite single-phase and austenite-ferrite dual-phase Fe-Mn-Al-C steels processed by different procedures are also statistically analyzed. The austenite single-phase steel was found to possess superior strength and plasticity. Three reasonable explanations for the mechanism of plastic deformation are presented, namely, shear band-induced plasticity, microband-induced plasticity, and slip band refinement-induced plasticity.

Fracture-Based Mesh Size Requirements for Matrix Cracks in Continuum Damage Mechanics Models

NASA Technical Reports Server (NTRS)

Leone, Frank A.; Davila, Carlos G.; Mabson, Gerald E.; Ramnath, Madhavadas; Hyder, Imran

2017-01-01

This paper evaluates the ability of progressive damage analysis (PDA) finite element (FE) models to predict transverse matrix cracks in unidirectional composites. The results of the analyses are compared to closed-form linear elastic fracture mechanics (LEFM) solutions. Matrix cracks in fiber-reinforced composite materials subjected to mode I and mode II loading are studied using continuum damage mechanics and zero-thickness cohesive zone modeling approaches. The FE models used in this study are built parametrically so as to investigate several model input variables and the limits associated with matching the upper-bound LEFM solutions. Specifically, the sensitivity of the PDA FE model results to changes in strength and element size are investigated.

Thermal Coefficient of Linear Expansion Modified by Dendritic Segregation in Nickel-Iron Alloys

NASA Astrophysics Data System (ADS)

Ogorodnikova, O. M.; Maksimova, E. V.

2018-05-01

The paper presents investigations of thermal properties of Fe-Ni and Fe-Ni-Co casting alloys affected by the heterogeneous distribution of their chemical elements. It is shown that nickel dendritic segregation has a negative effect on properties of studied invars. A mathematical model is proposed to explore the influence of nickel dendritic segregation on the thermal coefficient of linear expansion (TCLE) of the alloy. A computer simulation of TCLE of Fe-Ni-Co superinvars is performed with regard to a heterogeneous distribution of their chemical elements over the whole volume. The ProLigSol computer software application is developed for processing the data array and results of computer simulation.

An Overview of the Effects of Alloying Elements on the Properties of Lightweight Fe-(15-35) Mn-(5-12) Al-(0.3-1.2) C Steel

NASA Astrophysics Data System (ADS)

Xing, Jia; Wei, Yinghui; Hou, Lifeng

2018-04-01

In this review, the influences of alloying elements on the phase constitution, density, and stacking fault energy of Fe-(15-35) Mn-(5-12) Al-(0.3-1.2) C lightweight steel are discussed. The mechanical properties of austenite single-phase and austenite-ferrite dual-phase Fe-Mn-Al-C steels processed by different procedures are also statistically analyzed. The austenite single-phase steel was found to possess superior strength and plasticity. Three reasonable explanations for the mechanism of plastic deformation are presented, namely, shear band-induced plasticity, microband-induced plasticity, and slip band refinement-induced plasticity.

THE WEATHERING OF A SULFIDE OREBODY: SPECIATION AND FATE OF SOME POTENTIAL CONTAMINANTS

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

Courtin-Nomade, Alexandra; Grosbois, Cecile; Marcus, Matthew A.

2010-07-16

Various potentially toxic trace elements such as As, Cu, Pb and Zn have been remobilized by the weathering of a sulfide orebody that was only partially mined at Leona Heights, California. As a result, this body has both natural and anthropogenically modified weathering profiles only 500 m apart. The orebody is located in a heavily urbanized area in suburban Oakland, and directly affects water quality in at least one stream by producing acidic conditions and relatively high concentrations of dissolved elements (e.g., {approx}500 mg/L Cu, {approx}3700 mg/L Zn). Micrometric-scale mineralogical investigations were performed on the authigenic metal-bearing phases (less thanmore » 10 {mu}m in size) using electron-probe micro-analysis (EPMA), micro-Raman, micro X-ray absorption spectroscopy (mXAS), scanning X-ray diffraction (mSXRD) and scanning X-ray fluorescence (mSXRF) mapping techniques. Those measurements were coupled with classical mineralogical laboratory techniques, X-ray diffraction (XRD) and scanning electron microscopy (SEM). Authigenic metal-bearing phases identified are mainly sulfates (jarosite, epsomite, schwertmannite), Fe (oxy-)hydroxides (goethite, hematite and poorly crystalline Fe products) and poorly crystalline Mn (hydr-)oxides. Sulfates and Fe (oxy-)hydroxides are the two main secondary products at both sites, whereas Mn (hydr-) oxides were only observed in the samples from the non-mining site. In these samples, the various trace elements show different affinities for Fe or Mn compounds. Lead is preferentially associated with Mn (hydr-)oxides and As with Fe (oxy-)hydroxides or sulfates. Copper association with Mn and Fe phases is questionable, and the results obtained rather indicate that Cu is present as individual Cu-rich grains (Cu hydroxides). Some ochreous precipitates were found at both sites and correspond to a mixture of schwertmannite, goethite and jarosite containing some potentially toxic trace elements such as Cu, Pb and Zn. According to the trace element distribution and relative abundance of the unweathered sulfides, this orebody still represents a significant reservoir of potential contaminants for the watershed, especially in the non-mining site, as a much greater proportion of sulfides is left to react and because of the lower porosity in this site.« less

The weathering of a sulfide orebody: Speciation and fate of some potential contaminants

USGS Publications Warehouse

Courtin-Nomade, A.; Grosbois, C.; Marcus, M.A.; Fakra, S.C.; Beny, J.-M.; Foster, A.L.

2009-01-01

Various potentially toxic trace elements such as As, Cu, Pb and Zn have been remobilized by the weathering of a sulfide orebody that was only partially mined at Leona Heights, California. As a result, this body has both natural and anthropogeni- cally modified weathering profiles only 500 m apart. The orebody is located in a heavily urbanized area in suburban Oakland, and directly affects water quality in at least one stream by producing acidic conditions and relatively high concentrations of dissolved elements (e.g., ??500 ??g/L Cu, ??3700 ??g/L Zn). Micrometric-scale mineralogical investigations were performed on the authigenic metal-bearing phases (less than 10 ??m in size) using electron-probe micro-analysis (EPMA), micro-Raman, micro X-ray absorption spectroscopy (??XAS), scanning X-ray diffraction ((??SXRD) and scanning X-ray fluorescence (??-SXRF) mapping techniques. Those measurements were coupled with classical mineralogical laboratory techniques, X-ray diffraction (XRD) and scanning electron microscopy (SEM). Authigenic metal-bearing phases identified are mainly sulfates (jarosite, epsomite, schwertmannite), Fe (oxy-)hydroxides (goethite, hematite and poorly crystalline Fe products) and poorly crystalline Mn (hydr-)oxides. Sulfates and Fe (oxy-)hydroxides are the two main secondary products at both sites, whereas Mn (hydr-) oxides were only observed in the samples from the non-mining site. In these samples, the various trace elements show different affinities for Fe or Mn compounds. Lead is preferentially associated with Mn (hydr-)oxides and As with Fe (oxy-)hydroxides or sulfates. Copper association with Mn and Fe phases is questionable, and the results obtained rather indicate that Cu is present as individual Cu-rich grains (Cu hydroxides). Some ochreous precipitates were found at both sites and correspond to a mixture of schwertmannite, goethite and jarosite containing some potentially toxic trace elements such as Cu, Pb and Zn. According to the trace element distribution and relative abundance of the unweathered sulfides, this orebody still represents a significant reservoir of potential contaminants for the watershed, especially at the non-mining site, as a much greater proportion of sulfides is left to react and because of the lower porosity at this site.

Spatial transform coding of color images.

NASA Technical Reports Server (NTRS)

Pratt, W. K.

1971-01-01

The application of the transform-coding concept to the coding of color images represented by three primary color planes of data is discussed. The principles of spatial transform coding are reviewed and the merits of various methods of color-image representation are examined. A performance analysis is presented for the color-image transform-coding system. Results of a computer simulation of the coding system are also given. It is shown that, by transform coding, the chrominance content of a color image can be coded with an average of 1.0 bits per element or less without serious degradation. If luminance coding is also employed, the average rate reduces to about 2.0 bits per element or less.

Spatial distributions, fractionation characteristics, and ecological risk assessment of trace elements in sediments of Chaohu Lake, a large eutrophic freshwater lake in eastern China.

PubMed

Wu, Lei; Liu, Guijian; Zhou, Chuncai; Liu, Rongqiong; Xi, Shanshan; Da, Chunnian; Liu, Fei

2018-01-01

The concentrations, spatial distribution, fractionation characteristics, and potential ecological risks of trace elements (Cu, Pb, Zn, Cr, Ni, and Co) in the surface sediment samples collected from 32 sites in Chaohu Lake were investigated. The improved BCR sequential extraction procedure was applied to analyze the chemical forms of trace elements in sediments. The enrichment factor (EF), sediment quality guidelines (SQGs), potential ecological risk index (PERI), and risk assessment code (RAC) were employed to evaluate the pollution levels and the potential ecological risks. The results found that the concentrations of Cu, Pb, Zn, Cr, Ni, and Co in the surface sediments were 78.59, 36.91, 161.84, 98.87, 38.92, and 10.09 mg kg -1 , respectively. The lower concentrations of Cu, Pb, Zn, Cr, and Ni were almost found in the middle part of the lake, while Co increased from the western toward the eastern parts of the lake. Cr, Ni, Co, and Zn predominantly existed in the residual fractions, with the average values of 76.35, 59.22, 45.60, and 44.30%, respectively. Cu and Pb were mainly combined with Fe/Mn oxides in reducible fraction, with the average values of 66.4 and 69.1%, respectively. The pollution levels were different among the selected elements. Cu had the highest potential ecological risk, while Cr had the lowest potential ecological risk.

Highly Reducing Partitioning Experiments Relevant to the Planet Mercury

NASA Technical Reports Server (NTRS)

Rowland, Rick, II; Vander Kaaden, Kathleen E.; McCubbin, Francis M.; Danielson, Lisa R.

2017-01-01

With the data returned from the MErcury Surface Space ENvironment GEochemistry and Ranging (MESSENGER) mission, there are now numerous constraints on the physical and chemical properties of Mercury, including its surface composition. The high S and low FeO contents observed from MESSENGER on the planet's surface suggests a low oxygen fugacity of the present planetary materials. Estimates of the oxygen fugacity for Mercurian magmas are approximately 3-7 log units below the Iron-Wüstite (Fe-FeO) oxygen buffer, several orders of magnitude more reducing than other terrestrial bodies we have data from such as the Earth, Moon, or Mars. Most of our understanding of elemental partitioning behavior comes from observations made on terrestrial rocks, but Mercury's oxygen fugacity is far outside the conditions of those samples. With limited oxygen available, lithophile elements may instead exhibit chalcophile, halophile, or siderophile behaviors. Furthermore, very few natural samples of rocks that formed under reducing conditions are available in our collections (e.g., enstatite chondrites, achondrites, aubrites). With this limited amount of material, we must perform experiments to determine the elemental partitioning behavior of typically lithophile elements as a function of decreasing oxygen fugacity. Experiments are being conducted at 4 GPa in an 880-ton multi-anvil press, at temperatures up to 1850degC. The composition of starting materials for the experiments were selected for the final run products to contain metal, silicate melt, and sulfide melt phases. Oxygen fugacity is controlled in the experiments by adding silicon metal to the samples, using the Si-SiO2 oxygen buffer, which is approximately 5 log units more reducing than the Fe-FeO oxygen buffer at our temperatures of interest. The target silicate melt compositional is diopside (CaMgSi2O6) because measured surface compositions indicate partial melting of a pyroxene-rich mantle. Elements detected on Mercury's surface by MESSENGER (K, Na, Fe, Ti, Cl, Al, Cr, Mn, U, Th) and other geochemically relevant elements (P, F, H, N, C, Co, Ni, Mo, Ce, Nd, Sm, Eu, Gd, Dy, Yb) are added to the starting composition at trace abundances (approximately 500 ppm) so that they are close enough to infinite dilution to follow Henry's law of trace elements, and their partitioning behavior can be measured between the metal, silicate, and sulfide phases. The results of these experiments will allow us to assess the thermal and magmatic evolution of the planet Mercury from a geochemical standpoint.

Adaptation Reactions of Siderophilic Cyanobacteria to High and Low Levels Of Environmental Iron: Implications for Biosphere History

NASA Technical Reports Server (NTRS)

Brown, I. I.; Bryant, D.; Sarkisova, S.; Shen, G.; Garrison, D.; McKay, D. S.

2009-01-01

Of all extant environments, iron-depositing hot springs may constitute the most appropriate natural models (Pierson and Parenteau, 2000) for analysis of the ecophysiology of ancient cyanobacteria (CB) which may have emerged in association with hydrothermal activity (Brown et al., 2007) and elevated levels of environmental Fe (Rouxel et al., 2005). Elevated environmental Fe2+ posed a significant challenge to the first oxygenic phototrophs - CB - because reduced Fe2+ induces toxic Fenton reactions (Wiedenheft et al., 2005). Ancient CB could have also been stressed by occasional migrations from the Fe2+-rich Ocean to the basaltic land which was almost devoid of dissolved Fe2+. That is why the study of the adaptation reactions of siderophilic CB, which inhabit iron-depositing hot springs, to up and down shifts in levels of dissolved Fe may shed light on the paleophysiology of ancient oxygenic prokaryotes. Methods. Siderophilic CB (Brown et al., 2007) were cultivated in media with different concentrations of added Fe3+. In some cases basaltic rocks were used as a source of Fe and trace elements. The processes of Fe mineralization and rock dissolution were studied using TEM, SEM and EDS techniques. Fluorescence spectroscopy was used for checking chlorophyll-protein complexes. Results. It was found that five siderophilic isolates Chroogloeocystis siderophila, JSC-1, JSC-3, JSC-11 and JSC-12 precipitated Fe-bearing phases on the exopolymeric sheaths of their cells if [Fe3+] was approx. 400-600 M (high Fe). Same [Fe3+] was most optimal one for the cultures proliferation rate (Brown et al., 2005; Brown et al., 2007). Higher concentrations of Fe3+ repressed the growth of some siderophilic CB (Brown et al., 2005). No mineralized Fe3+ was observed on the sheath of freshwater isolates Synechocystis sp. PCC 6803 and Phormidium aa. Scanning TEM in conjunction with thin-window energy dispersive X-ray spectroscopy (EDS) revealed intracellular Fe-rich phases within all three isolates studied JSC-1, JSC-3 and JSC-11. The elemental composition of the Fe-rich precipitates indicates P, Fe, and O as the major elements with minor amounts of Al and Ca. It was also found that the PSI:PSII ratio is higher in JSC-1 and JSC-3 isolates than in CB without detectable ability to mineralize Fe. SEM-EDS studies of the interaction of siderophilic cyanobacteria with Fe-rich minerals and rocks revealed, for the first time, their ability to leach ilmenite, olivine, FeS, ZnS and ferrosilicates, perhaps because the cyanobacteria studied can secrete 2-oxo-glutarate and malate which possess chelating properties. The draft of Cyanobacterium JSC-1 is currently being completed. This will help to verify the molecular mechanisms of Fe mineralization and Fe-rich minerals by siderophilic CB. Conclusions. The results obtained suggest that colloidal Fe3+ is transported in CB cytoplasm most likely through ABC-type Fe3+ transport system (Braun et al., 2004). The prevalence of PSI components over PSII in some species of siderophilic CB may indirectly support the Y. Cohen s hypothesis that PSI in cyanobacteria can be involved in Fe2+ oxidation (Cohen, 1984; 1989). The ability of siderophilic CB to mineralize Fe within their cytoplasms could be a protective survival mechanism induced by high levels of [Fe2+] and UV radiation, while the ability to leach Fe-rich minerals could have supported the expansion of ancient CB onto basaltic land.

NPKS uptake, sensing, and signaling and miRNAs in plant nutrient stress.

PubMed

Nath, Manoj; Tuteja, Narendra

2016-05-01

Sessile nature of higher plants consequently makes it highly adaptable for nutrient absorption and acquisition from soil. Plants require 17 essential elements for their growth and development which include 14 minerals (macronutrients: N, P, K, Mg, Ca, S; micronutrients: Cl, Fe, B, Mn, Zn, Cu, Ni, Mo) and 3 non-mineral (C, H, O) elements. The roots of higher plants must acquire these macronutrients and micronutrients from rhizosphere and further allocate to other plant parts for completing their life cycle. Plants evolved an intricate series of signaling and sensing cascades to maintain nutrient homeostasis and to cope with nutrient stress/availability. The specific receptors for nutrients in root, root system architecture, and internal signaling pathways help to develop plasticity in response to the nutrient starvation. Nitrogen (N), phosphorus (P), potassium (K), and sulfur (S) are essential for various metabolic processes, and their deficiency negatively effects the plant growth and yield. Genes coding for transporters and receptors for nutrients as well as some small non-coding RNAs have been implicated in nutrient uptake and signaling. This review summarizes the N, P, K, and S uptake, sensing and signaling events in nutrient stress condition especially in model plant Arabidopsis thaliana and involvement of microRNAs in nutrient deficiency. This article also provides a framework of uptake, sensing, signaling and to highlight the microRNA as an emerging major players in nutrient stress condition. Nutrient-plant-miRNA cross talk may help plant to cope up nutrient stress, and understanding their precise mechanism(s) will be necessary to develop high yielding smart crop with low nutrient input.

A Multiscale Progressive Failure Modeling Methodology for Composites that Includes Fiber Strength Stochastics

NASA Technical Reports Server (NTRS)

Ricks, Trenton M.; Lacy, Thomas E., Jr.; Bednarcyk, Brett A.; Arnold, Steven M.; Hutchins, John W.

2014-01-01

A multiscale modeling methodology was developed for continuous fiber composites that incorporates a statistical distribution of fiber strengths into coupled multiscale micromechanics/finite element (FE) analyses. A modified two-parameter Weibull cumulative distribution function, which accounts for the effect of fiber length on the probability of failure, was used to characterize the statistical distribution of fiber strengths. A parametric study using the NASA Micromechanics Analysis Code with the Generalized Method of Cells (MAC/GMC) was performed to assess the effect of variable fiber strengths on local composite failure within a repeating unit cell (RUC) and subsequent global failure. The NASA code FEAMAC and the ABAQUS finite element solver were used to analyze the progressive failure of a unidirectional SCS-6/TIMETAL 21S metal matrix composite tensile dogbone specimen at 650 degC. Multiscale progressive failure analyses were performed to quantify the effect of spatially varying fiber strengths on the RUC-averaged and global stress-strain responses and failure. The ultimate composite strengths and distribution of failure locations (predominately within the gage section) reasonably matched the experimentally observed failure behavior. The predicted composite failure behavior suggests that use of macroscale models that exploit global geometric symmetries are inappropriate for cases where the actual distribution of local fiber strengths displays no such symmetries. This issue has not received much attention in the literature. Moreover, the model discretization at a specific length scale can have a profound effect on the computational costs associated with multiscale simulations.models that yield accurate yet tractable results.

Experiment to measure oxygen opacity at high density and temperature

NASA Astrophysics Data System (ADS)

Keiter, Paul; Mussack, Katie; Orban, Chris; Colgan, James; Ducret, Jean-Eric; Fontes, Christopher J.; Guzik, Joyce Ann; Heeter, Robert F.; Kilcrease, Dave; Le Pennec, Maelle; Mancini, Roberto; Perry, Ted; Turck-Chièze, Sylvaine; Trantham, Matt

2017-06-01

In recent years, there has been a debate over the abundances of heavy elements (Z >2) in the solar interior. Recent solar atmosphere models [Asplund 2009] find a significantly lower abundance for C, N, and O compared to models used roughly a decade ago. This discrepancy has led to an investigation of opacities through laboratory experiments and improved opacity models for many of the larger contributors to the sun’s opacity, including iron and oxygen. Recent opacity measurements of iron disagree with opacity model predictions [Bailey et al, 2015]. Although these results are still controversial, repeated scrutiny of the experiment and data has not produced a conclusive reason for the discrepancy. New models have been implemented in the ATOMIC opacity code for C, O and Fe to address the solar abundance issue [Colgan, 2013]. Armstrong et al [2014] have also implemented changes in the ATOMIC code for low-Z elements. However, no data currently exists to test the low-Z material models in the regime relevant to the solar convection zone. We present an experimental design using the opacity platform developed at the National Ignition Facility to study the oxygen opacity at densities and temperatures near the solar convection zone conditions.This work is funded by the U.S. DOE, through the NNSA-DS and SC-OFES Joint Program in HEDPLP, grant No. DE-NA0001840, and the NLUF Program, grant No. DE-NA0000850, and through LLE, University of Rochester by the NNSA/OICF under Agreement No. DE-FC52-08NA28302.

Microplankton trace element contents: implications for mineral limitation of mesozooplankton in an HNLC area

PubMed Central

Baines, Stephen B.; Chen, Xi; Vogt, Stefan; Fisher, Nicholas S.; Twining, Benjamin S.; Landry, Michael R.

2016-01-01

Mesozooplankton production in high-nutrient low-chlorophyll regions of the ocean may be reduced if the trace element concentrations in their food are insufficient to meet growth and metabolic demands. We used elemental microanalysis (SXRF) of single-celled plankton to determine their trace metal contents during a series of semi-Lagrangian drift studies in an HNLC upwelling region, the Costa Rica Dome (CRD). Cells from the surface mixed layer had lower Fe:S but higher Zn:S and Ni:S than those from the subsurface chlorophyll maximum at 22–30 m. Diatom Fe:S values were typically 3-fold higher than those in flagellated cells. The ratios of Zn:C in flagellates and diatoms were generally similar to each other, and to co-occurring mesozooplankton. Estimated Fe:C ratios in flagellates were lower than those in co-occurring mesozooplankton, sometimes by more than 3-fold. In contrast, Fe:C in diatoms was typically similar to that in zooplankton. RNA:DNA ratios in the CRD were low compared with other regions, and were related to total autotrophic biomass and weakly to the discrepancy between Zn:C in flagellated cells and mesozooplankton tissues. Mesozooplankton may have been affected by the trace element content of their food, even though trace metal limitation of phytoplankton was modest at best. PMID:27275029

Effects of chemical alternation on damage accumulation in concentrated solid-solution alloys

DOE PAGES

Ullah, Mohammad W.; Xue, Haizhou; Velisa, Gihan; ...

2017-06-23

Single-phase concentrated solid-solution alloys (SP-CSAs) have recently gained unprecedented attention due to their promising properties. To understand effects of alloying elements on irradiation-induced defect production, recombination and evolution, an integrated study of ion irradiation, ion beam analysis and atomistic simulations are carried out on a unique set of model crystals with increasing chemical complexity, from pure Ni to Ni 80Fe 20, Ni 50Fe 50, and Ni 80Cr 20 binaries, and to a more complex Ni 40Fe 40Cr 20 alloy. Both experimental and simulation results suggest that the binary and ternary alloys exhibit higher radiation resistance than elemental Ni. The modelingmore » work predicts that Ni 40Fe 40Cr 20 has the best radiation tolerance, with the number of surviving Frenkel pairs being factors of 2.0 and 1.4 lower than pure Ni and the 80:20 binary alloys, respectively. While the reduced defect mobility in SP-CSAs is identified as a general mechanism leading to slower growth of large defect clusters, the effect of specific alloying elements on suppression of damage accumulation is clearly demonstrated. This work suggests that concentrated solid-solution provides an effective way to enhance radiation tolerance by creating elemental alternation at the atomic level. The demonstrated chemical effects on defect dynamics may inspire new design principles of radiation-tolerant structural alloys for advanced energy systems.« less

Expression in Escherichia coli and characterization of a recombinant 7Fe ferredoxin of Rhodobacter capsulatus.

PubMed Central

Jouanneau, Y; Duport, C; Meyer, C; Gaillard, J

1992-01-01

The 7Fe ferredoxin of Rhodobacter capsulatus (FdII) could be expressed in Escherichia coli by cloning the fdxA gene coding for FdII downstream from the lac promoter. The expressed recombinant ferredoxin appeared as a brown protein which was specifically recognized in E. coli cell-free extracts by anti-FdII serum. The purified recombinant ferredoxin was indistinguishable from R. capsulatus FdII on the basis of its molecular, redox and spectroscopic properties. These results indicate that the [3Fe-4S] and [4Fe-4S] clusters were correctly inserted into the recombinant ferredoxin. Images Fig. 2. PMID:1325780

An emulator for minimizing computer resources for finite element analysis

NASA Technical Reports Server (NTRS)

Melosh, R.; Utku, S.; Islam, M.; Salama, M.

1984-01-01

A computer code, SCOPE, has been developed for predicting the computer resources required for a given analysis code, computer hardware, and structural problem. The cost of running the code is a small fraction (about 3 percent) of the cost of performing the actual analysis. However, its accuracy in predicting the CPU and I/O resources depends intrinsically on the accuracy of calibration data that must be developed once for the computer hardware and the finite element analysis code of interest. Testing of the SCOPE code on the AMDAHL 470 V/8 computer and the ELAS finite element analysis program indicated small I/O errors (3.2 percent), larger CPU errors (17.8 percent), and negligible total errors (1.5 percent).

Performance of an MPI-only semiconductor device simulator on a quad socket/quad core InfiniBand platform.

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

Shadid, John Nicolas; Lin, Paul Tinphone

2009-01-01

This preliminary study considers the scaling and performance of a finite element (FE) semiconductor device simulator on a capacity cluster with 272 compute nodes based on a homogeneous multicore node architecture utilizing 16 cores. The inter-node communication backbone for this Tri-Lab Linux Capacity Cluster (TLCC) machine is comprised of an InfiniBand interconnect. The nonuniform memory access (NUMA) nodes consist of 2.2 GHz quad socket/quad core AMD Opteron processors. The performance results for this study are obtained with a FE semiconductor device simulation code (Charon) that is based on a fully-coupled Newton-Krylov solver with domain decomposition and multilevel preconditioners. Scaling andmore » multicore performance results are presented for large-scale problems of 100+ million unknowns on up to 4096 cores. A parallel scaling comparison is also presented with the Cray XT3/4 Red Storm capability platform. The results indicate that an MPI-only programming model for utilizing the multicore nodes is reasonably efficient on all 16 cores per compute node. However, the results also indicated that the multilevel preconditioner, which is critical for large-scale capability type simulations, scales better on the Red Storm machine than the TLCC machine.« less

Thermo-Mechanical Analysis of a Single-Pass Weld Overlay and Girth Welding in Lined Pipe

NASA Astrophysics Data System (ADS)

Obeid, Obeid; Alfano, Giulio; Bahai, Hamid

2017-08-01

The paper presents a nonlinear heat-transfer and mechanical finite-element (FE) analyses of a two-pass welding process of two segments of lined pipe made of a SUS304 stainless steel liner and a C-Mn steel pipe. The two passes consist of the single-pass overlay welding (inner lap weld) of the liner with the C-Mn steel pipe for each segment and the single-pass girth welding (outer butt weld) of the two segments. A distributed power density of the moving welding torch and a nonlinear heat-transfer coefficient accounting for both radiation and convection have been used in the analysis and implemented in user subroutines for the FE code ABAQUS. The modeling procedure has been validated against previously published experimental results for stainless steel and carbon steel welding separately. The model has been then used to determine the isotherms induced by the weld overlay and the girth welding and to clarify their influence on the transient temperature field and residual stress in the lined pipe. Furthermore, the influence of the cooling time between weld overlay and girth welding and of the welding speed have been examined thermally and mechanically as they are key factors that can affect the quality of lined pipe welding.

VizieR Online Data Catalog: Example of FERRE code spectra (Aguado+, 2017)

NASA Astrophysics Data System (ADS)

Aguado, D. S.; Gonzalez Hernandez, J. I.; Allende Prieto, C.; Rebolo, R.

2017-05-01

FERRE matches physical models to observed data. It was created to deal with the common problem of having numerical models that are costly to evaluate, and need to be used to interpret large data sets. ferre.pdf file contains the FERRE uses's guide. The code can be obtained from http://hebe.as.utexas.edu/ferre Example : f_crump3h.dat is a tool usable with FERRE with the parameters shown in its header: Resolving Power:10.000 3600 <= λ <= 9000Å, -6 <= [Fe/H] <=-2, -1 <= [C/Fe] <= 5, 4750 <= Tefff <= 7000, 1.0 <= logg <= 5.0, It is the grid used for the paper. (2 data files).

Absolute Photoionization Cross Section for Fe6+ to Fe10+ Ions in the Photon Energy Region of the 2p–3d Resonance Lines

NASA Astrophysics Data System (ADS)

Blancard, C.; Cubaynes, D.; Guilbaud, S.; Bizau, J.-M.

2018-01-01

Resonant single photoionization cross sections of Fen+ (n = 6 to 10) ions have been measured in absolute values using a merged-beams setup at the SOLEIL synchrotron radiation facility. Photon energies were between about 710 and 780 eV, covering the range of the 2p–3d transitions. The experimental cross sections are compared to calculations we performed using a multi-configuration Dirac–Fock code and the OPAS code dedicated to radiative opacity calculations. Comparisons are also done with the Chandra X-ray observatory NGC 3783 spectra and with the results of previously published calculations.

Effect of silicon on activity coefficients of siderophile elements (Au, Pd, Pt, P, Ga, Cu, Zn, and Pb) in liquid Fe: Roles of core formation, late sulfide matte, and late veneer in shaping terrestrial mantle geochemistry

NASA Astrophysics Data System (ADS)

Righter, K.; Pando, K.; Humayun, M.; Waeselmann, N.; Yang, S.; Boujibar, A.; Danielson, L. R.

2018-07-01

Earth's core contains ∼10% of a light element that may be a combination of Si, S, C, O or H, with Si potentially being the major light element. Metal-silicate partitioning of siderophile elements can place important constraints on the P-T-fO2 and composition of the early Earth, but the effect of Si alloyed in Fe liquids is unknown for many of these elements. In particular, the effect of Si on the partitioning of highly siderophile elements (Au, Re and PGE) is virtually unknown. To address this gap in understanding, we have undertaken a systematic study of the highly siderophile elements Au, Pd, and Pt, and the volatile siderophile elements P, Ga, Cu, Zn, and Pb at variable Si content of metal, and 1600 °C and 1 GPa. From our experiments we derive epsilon interaction parameters between these elements and Si in Fe metallic liquids. The new parameters are used to update an activity model for trace siderophile elements in Fe alloys; Si causes large variation in the magnitude of activity coefficients of these elements in FeSi liquids. Because the interaction parameters are all positive, Si causes a decrease in their metal/silicate partition coefficients. We combine these new activity results with experimental studies of Au, Pd, Pt, P, Ga, Cu, Zn and Pb, to derive predictive expressions for metal/silicate partition coefficients which can then be applied to Earth. The expressions are applied to two scenarios for continuous accretion of Earth; specifically for constant and increasing fO2 during accretion. The results indicate that mantle concentrations of P, Ga, Cu, Zn, and Pb can be explained by metal-silicate equilibrium during accretion of the Earth where Earth's early magma ocean deepens to pressures of 40-60 GPa. Au, Pd, and Pt, on the other hand become too high in the mantle in such a scenario, and require a later removal mechanism, rather than an addition as traditionally argued. A late reduction event that removes 0.5% metal from a shallow magma ocean can lower the Au, Pd, and Pt contents to values near the current day BSE. On the other hand, removal of 0.2-1.0% of a late sulfide-rich matte to the core would lower the Au, Pd, and Pt concentrations in the mantle, but not to chondritic relative concentrations observed in the BSE. If sulfide matte is called upon to remove HSEs, they must be later added via a late veneer to re-establish the high and chondritic relative PUM concentrations. These results suggest that although accretion and core formation (involving a Si, S, and C-bearing metallic liquid) were the primary processes establishing many of Earth's mantle volatile elements and HSE, a secondary removal process is required to establish HSEs at their current and near-chondritic relative BSE levels. Mn and P - two siderophile elements that are central to biochemical processes (photosynthesis and triphosphates, respectively) - have significant and opposite interactions with FeSi liquids, and their mantle concentrations would be notably different if Earth had a Si-free core.

Magnetic safety matches

NASA Astrophysics Data System (ADS)

Lindén, J.; Lindberg, M.; Greggas, A.; Jylhävuori, N.; Norrgrann, H.; Lill, J. O.

2017-07-01

In addition to the main ingredients; sulfur, potassium chlorate and carbon, ordinary safety matches contain various dyes, glues etc, giving the head of the match an even texture and appealing color. Among the common reddish-brown matches there are several types, which after ignition can be attracted by a strong magnet. Before ignition the match head is generally not attracted by the magnet. An elemental analysis based on proton-induced x-ray emission was performed to single out iron as the element responsible for the observed magnetism. 57Fe Mössbauer spectroscopy was used for identifying the various types of iron-compounds, present before and after ignition, responsible for the macroscopic magnetism: Fe2O3 before and Fe3O4 after. The reaction was verified by mixing the main chemicals in the match-head with Fe2O3 in glue and mounting the mixture on a match stick. The ash residue after igniting the mixture was magnetic.

Corrosion behavior in high-temperature pressurized water of Zircaloy-4 joints brazed with Zr-Cu-based amorphous filler alloys

NASA Astrophysics Data System (ADS)

Lee, Jung Gu; Lee, Gyoung-Ja; Park, Jin-Ju; Lee, Min-Ku

2017-05-01

The compositional effects of ternary Zr-Cu-X (X: Al, Fe) amorphous filler alloys on galvanic corrosion susceptibility in high-temperature pressurized water were investigated for Zircaloy-4 brazed joints. Through an Al-induced microgalvanic reaction that deteriorated the overall nobility of the joint, application of the Zr-Cu-Al filler alloy caused galvanic coupling to develop readily between the Al-bearing joint and the Al-free base metal, finally leading to massive localized corrosion of the joint. Contrastingly, joints prepared with a Zr-Cu-Fe filler alloy showed excellent corrosion resistance comparable to that of the Zircaloy-4 base metal, since the Cu and Fe elements forming fine intermetallic particles with Zr did not influence the electrochemical stability of the resultant joints. The present results demonstrate that Fe is a more suitable alloying element than Al for brazing filler alloys subjected to high-temperature corrosive environments.

Comparative microstructures and cytotoxicity assays for ballistic aerosols composed of micrometals and nanometals: respiratory health implications

PubMed Central

Machado, Brenda I; Suro, Raquel M; Garza, Kristine M; Murr, Lawrence E

2011-01-01

Aerosol particulates collected on filters from ballistic penetration and erosion events for W–Ni–Co and W–Ni–Fe kinetic energy rod projectiles penetrating steel target plates were observed to be highly cytotoxic to human epithelial A549 lung cells in culture after 48 hours of exposure. The aerosol consisted of micron-sized Fe particulates and nanoparticulate aggregates consisting of W, Ni or W, Co, and some Fe, characterized by scanning electron microscopy and transmission electron microscopy, and using energy-dispersive (X-ray) spectrometry for elemental analysis and mapping. Cytotoxic assays of manufactured micron-sized and nanosized metal particulates of W, Ni, Fe, and Co demonstrated that, consistent with many studies in the literature, only the nanoparticulate elements demonstrated measurable cytotoxicity. These results suggest the potential for very severe, short-term, human toxicity, in particular to the respiratory system on inhaling ballistic aerosols. PMID:21499416

Concentrations of radioactive elements in lunar materials

NASA Astrophysics Data System (ADS)

Korotev, Randy L.

1998-01-01

As an aid to interpreting data obtained remotely on the distribution of radioactive elements on the lunar surface, average concentrations of K, U, and Th as well as Al, Fe, and Ti in different types of lunar rocks and soils are tabulated. The U/Th ratio in representative samples of lunar rocks and regolith is constant at 0.27; K/Th ratios are more variable because K and Th are carried by different mineral phases. In nonmare regoliths at the Apollo sites, the main carriers of radioactive elements are mafic (i.e., 6-8 percent Fe) impact-melt breccias created at the time of basin formation and products derived therefrom.

Characteristics and source identification of dissolved trace elements in the Jinshui River of the South Qinling Mts., China.

PubMed

Bu, Hongmei; Wang, Weibo; Song, Xianfang; Zhang, Quanfa

2015-09-01

Dissolved trace elements and physiochemical parameters were analyzed to investigate their physicochemical characteristics and identify their sources at 12 sampling sites of the Jinshui River in the South Qinling Mts., China from October 2006 to November 2008. The two-factor ANOVA indicated significant temporal variations of the dissolved Cu, Fe, Sr, Si, and V (p < 0.001 or p < 0.05). With the exception of Sr (p < 0.001), no significant spatial variations were found. Distributions and concentrations of the dissolved trace elements displayed that dissolved Cu, Fe, Sr, Si, V, and Cr were originated from chemical weathering and leaching from the soil and bedrock. Dissolved Cu, Fe, Sr, As, and Si were also from anthropogenic inputs (farming and domestic effluents). Correlation and regression analysis showed that the chemical and physical processes of dissolved Cu was influenced by water temperature and dissolved oxygen (DO) to some degree. Dissolved Fe and Sr were affected by colloid destabilization or sedimentary inputs. Concentrations of dissolved Si were slightly controlled by biological uptake. Principal component analysis confirmed that Fe, Sr, and V resulted from domestic effluents, agricultural runoff, and confluence, whereas As, Cu, and Si were from agricultural activities, and Cr and Zn through natural processes. The research results provide a reference for ecological restoration and protection of the river environment in the Qinling Mts., China.

To generate a finite element model of human thorax using the VCH dataset

NASA Astrophysics Data System (ADS)

Shi, Hui; Liu, Qian

2009-10-01

Purpose: To generate a three-dimensional (3D) finite element (FE) model of human thorax which may provide the basis of biomechanics simulation for the study of design effect and mechanism of safety belt when vehicle collision. Methods: Using manually or semi-manually segmented method, the interested area can be segmented from the VCH (Visible Chinese Human) dataset. The 3D surface model of thorax is visualized by using VTK (Visualization Toolkit) and further translated into (Stereo Lithography) STL format, which approximates the geometry of solid model by representing the boundaries with triangular facets. The data in STL format need to be normalized into NURBS surfaces and IGES format using software such as Geomagic Studio to provide archetype for reverse engineering. The 3D FE model was established using Ansys software. Results: The generated 3D FE model was an integrated thorax model which could reproduce human's complicated structure morphology including clavicle, ribs, spine and sternum. It was consisted of 1 044 179 elements in total. Conclusions: Compared with the previous thorax model, this FE model enhanced the authenticity and precision of results analysis obviously, which can provide a sound basis for analysis of human thorax biomechanical research. Furthermore, using the method above, we can also establish 3D FE models of some other organizes and tissues utilizing the VCH dataset.

CHEMICAL DIVERSITY IN THE ULTRA-FAINT DWARF GALAXY TUCANA II

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

Ji, Alexander P.; Frebel, Anna; Ezzeddine, Rana

We present the first detailed chemical abundance study of the ultra-faint dwarf galaxy Tucana II, based on high-resolution Magellan/MIKE spectra of four red giant stars. The metallicities of these stars range from [Fe/H] = −3.2 to −2.6, and all stars are low in neutron-capture abundances ([Sr/Fe] and [Ba/Fe] < −1). However, a number of anomalous chemical signatures are present. One star is relatively metal-rich ([Fe/H] = −2.6) and shows [Na, α , Sc/Fe] < 0, suggesting an extended star formation history with contributions from AGB stars and SNe Ia. Two stars with [Fe/H] < −3 are mildly carbon-enhanced ([C/Fe] ∼more » 0.7) and may be consistent with enrichment by faint supernovae, if such supernovae can produce neutron-capture elements. A fourth star with [Fe/H] = −3 is carbon-normal, and exhibits distinct light element abundance ratios from the carbon-enhanced stars. This carbon-normal star implies that at least two distinct nucleosynthesis sources, both possibly associated with Population III stars, contributed to the early chemical enrichment of this galaxy. Despite its very low luminosity, Tucana II shows a diversity of chemical signatures that preclude it from being a simple “one-shot” first galaxy yet still provide a window into star and galaxy formation in the early universe.« less

Iron rich low cost superalloys. Ph.D. Thesis. Final Report

NASA Technical Reports Server (NTRS)

Wayne, S. F.

1985-01-01

An iron-rich low-cost superalloy was developed. The alloy, when processed by conventional chill casting, has physical and mechanical properties that compare favorably with existing nickel and cobalt based superalloys while containing significantly lower amounts of strategic elements. Studies were also made on the properties of Cr(20)-Mn(10)-C(3.4)-Fe(bal.), a eutectic alloy processed by chill casting and directional solidification which produced an aligned microstructure consisting of M7C3 fibers in a gamma-Fe matrix. Thermal expansion of the M7C3 (M = Fe, Cr, Mn) carbide lattice was measured up to 800 C and found to be highly anisotropic, with the a-axis being the predominant mode of expansion. Repetitive impact sliding wear experiments performed with the Fe rich eutectic alloy showed that the directionally solidified microstructure greatly improved the alloy's wear resistance as compared to the chill cast microstructure and conventional nickel base superalloys. Studies on the molybdenum cementite phase prove that the crystal structure of the xi phase is not orthorhombic. The crystal structure of the xi phase is made up of octahedra building elements consisting of four Mo and two Fe atoms and trigonal prisms consisting of four Fe and two Mo atoms. The voids are occupied by carbon atoms. The previous chemical formula for the molybdenum cementite MoFe2C is now clearly seen to be Mo12Fe22C10.

Novel Experimental Simulations of the Atmospheric Injection of Meteoric Metals

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

Gómez Martín, J. C.; Bones, D. L.; Carrillo-Sánchez, J. D.

2017-02-20

A newly developed laboratory, Meteoric Ablation Simulator (MASI), is used to test model predictions of the atmospheric ablation of interplanetary dust particles (IDPs) with experimental Na, Fe, and Ca vaporization profiles. MASI is the first laboratory setup capable of performing time-resolved atmospheric ablation simulations, by means of precision resistive heating and atomic laser-induced fluorescence detection. Experiments using meteoritic IDP analogues show that at least three mineral phases (Na-rich plagioclase, metal sulfide, and Mg-rich silicate) are required to explain the observed appearance temperatures of the vaporized elements. Low melting temperatures of Na-rich plagioclase and metal sulfide, compared to silicate grains, precludemore » equilibration of all the elemental constituents in a single melt. The phase-change process of distinct mineral components determines the way in which Na and Fe evaporate. Ca evaporation is dependent on particle size and on the initial composition of the molten silicate. Measured vaporized fractions of Na, Fe, and Ca as a function of particle size and speed confirm differential ablation (i.e., the most volatile elements such as Na ablate first, followed by the main constituents Fe, Mg, and Si, and finally the most refractory elements such as Ca). The Chemical Ablation Model (CABMOD) provides a reasonable approximation to this effect based on chemical fractionation of a molten silicate in thermodynamic equilibrium, even though the compositional and geometric description of IDPs is simplistic. Improvements in the model are required in order to better reproduce the specific shape of the elemental ablation profiles.« less