determined heavy atom: Topics by Science.gov

Sample records for determined heavy atom

Direct demodulation method for heavy atom position determination in protein crystallography

NASA Astrophysics Data System (ADS)

Zhou, Liang; Liu, Zhong-Chuan; Liu, Peng; Dong, Yu-Hui

2013-01-01

The first step of phasing in any de novo protein structure determination using isomorphous replacement (IR) or anomalous scattering (AD) experiments is to find heavy atom positions. Traditionally, heavy atom positions can be solved by inspecting the difference Patterson maps. Due to the weak signals in isomorphous or anomalous differences and the noisy background in the Patterson map, the search for heavy atoms may become difficult. Here, the direct demodulation (DD) method is applied to the difference Patterson maps to reduce the noisy backgrounds and sharpen the signal peaks. The real space Patterson search by using these optimized maps can locate the heavy atom positions more accurately. It is anticipated that the direct demodulation method can assist in heavy atom position determination and facilitate the de novo structure determination of proteins.
A rapid and rational approach to generating isomorphous heavy-atom phasing derivatives

PubMed Central

Lu, Jinghua; Sun, Peter D.

2014-01-01

In attempts to replace the conventional trial-and-error heavy-atom derivative search method with a rational approach, we previously defined heavy metal compound reactivity against peptide ligands. Here, we assembled a composite pH and buffer-dependent peptide reactivity profile for each heavy metal compound to guide rational heavy-atom derivative search. When knowledge of the best-reacting heavy-atom compound is combined with mass spectrometry-assisted derivatization, and with a quick-soak method to optimize phasing, it is likely that the traditional heavy-atom compounds could meet the demand of modern high-throughput X-ray crystallography. As an example, we applied this rational heavy-atom phasing approach to determine a previously unknown mouse serum amyloid A2 crystal structure. PMID:25040395
Towards a rational approach for heavy-atom derivative screening in protein crystallography

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

Agniswamy, Johnson; Joyce, M. Gordon; Hammer, Carl H.

2008-04-01

Heavy-atom derivatization is routinely used in protein structure determination and is thus of critical importance in structural biology. In order to replace the current trial-and-error heavy-atom derivative screening with a knowledge-based rational derivative-selection method, the reactivity of more than 40 heavy-atom compounds over a wide range of buffer and pH values was systematically examined using peptides which contained a single reactive amino-acid residue. Heavy-atom derivatization is routinely used in protein structure determination and is thus of critical importance in structural biology. In order to replace the current trial-and-error heavy-atom derivative screening with a knowledge-based rational derivative-selection method, the reactivity ofmore » more than 40 heavy-atom compounds over a wide range of buffer and pH values was systematically examined using peptides which contained a single reactive amino-acid residue. Met-, Cys- and His-containing peptides were derivatized against Hg, Au and Pt compounds, while Tyr-, Glu-, Asp-, Asn- and Gln-containing peptides were assessed against Pb compounds. A total of 1668 reactive conditions were examined using mass spectrometry and were compiled into heavy-atom reactivity tables. The results showed that heavy-atom derivatization reactions are highly linked to buffer and pH, with the most accommodating buffer being MES at pH 6. A group of 21 compounds were identified as most successful irrespective of ligand or buffer/pH conditions. To assess the applicability of the peptide heavy-atom reactivity to proteins, lysozyme crystals were derivatized with a list of peptide-reactive compounds that included both known and new compounds for lysozyme derivatization. The results showed highly consistent heavy-atom reactivities between the peptides and lysozyme.« less
Initiating heavy-atom-based phasing by multi-dimensional molecular replacement.

PubMed

Pedersen, Bjørn Panyella; Gourdon, Pontus; Liu, Xiangyu; Karlsen, Jesper Lykkegaard; Nissen, Poul

2016-03-01

To obtain an electron-density map from a macromolecular crystal the phase problem needs to be solved, which often involves the use of heavy-atom derivative crystals and concomitant heavy-atom substructure determination. This is typically performed by dual-space methods, direct methods or Patterson-based approaches, which however may fail when only poorly diffracting derivative crystals are available. This is often the case for, for example, membrane proteins. Here, an approach for heavy-atom site identification based on a molecular-replacement parameter matrix (MRPM) is presented. It involves an n-dimensional search to test a wide spectrum of molecular-replacement parameters, such as different data sets and search models with different conformations. Results are scored by the ability to identify heavy-atom positions from anomalous difference Fourier maps. The strategy was successfully applied in the determination of a membrane-protein structure, the copper-transporting P-type ATPase CopA, when other methods had failed to determine the heavy-atom substructure. MRPM is well suited to proteins undergoing large conformational changes where multiple search models should be considered, and it enables the identification of weak but correct molecular-replacement solutions with maximum contrast to prime experimental phasing efforts.
Initiating heavy-atom-based phasing by multi-dimensional molecular replacement

PubMed Central

Pedersen, Bjørn Panyella; Gourdon, Pontus; Liu, Xiangyu; Karlsen, Jesper Lykkegaard; Nissen, Poul

2016-01-01

To obtain an electron-density map from a macromolecular crystal the phase problem needs to be solved, which often involves the use of heavy-atom derivative crystals and concomitant heavy-atom substructure determination. This is typically performed by dual-space methods, direct methods or Patterson-based approaches, which however may fail when only poorly diffracting derivative crystals are available. This is often the case for, for example, membrane proteins. Here, an approach for heavy-atom site identification based on a molecular-replacement parameter matrix (MRPM) is presented. It involves an n-dimensional search to test a wide spectrum of molecular-replacement parameters, such as different data sets and search models with different conformations. Results are scored by the ability to identify heavy-atom positions from anomalous difference Fourier maps. The strategy was successfully applied in the determination of a membrane-protein structure, the copper-transporting P-type ATPase CopA, when other methods had failed to determine the heavy-atom substructure. MRPM is well suited to proteins undergoing large conformational changes where multiple search models should be considered, and it enables the identification of weak but correct molecular-replacement solutions with maximum contrast to prime experimental phasing efforts. PMID:26960131
A rapid and rational approach to generating isomorphous heavy-atom phasing derivatives.

PubMed

Lu, Jinghua; Sun, Peter D

2014-09-01

In attempts to replace the conventional trial-and-error heavy-atom derivative search method with a rational approach, we previously defined heavy metal compound reactivity against peptide ligands. Here, we assembled a composite pH- and buffer-dependent peptide reactivity profile for each heavy metal compound to guide rational heavy-atom derivative search. When knowledge of the best-reacting heavy-atom compound is combined with mass spectrometry assisted derivatization, and with a quick-soak method to optimize phasing, it is likely that the traditional heavy-atom compounds could meet the demand of modern high-throughput X-ray crystallography. As an example, we applied this rational heavy-atom phasing approach to determine a previously unknown mouse serum amyloid A2 crystal structure. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.
A rational approach to heavy-atom derivative screening

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

Joyce, M. Gordon; Radaev, Sergei; Sun, Peter D., E-mail: psun@nih.gov

2010-04-01

In order to overcome the difficulties associated with the ‘classical’ heavy-atom derivatization procedure, an attempt has been made to develop a rational crystal-free heavy-atom-derivative screening method and a quick-soak derivatization procedure which allows heavy-atom compound identification. Despite the development in recent times of a range of techniques for phasing macromolecules, the conventional heavy-atom derivatization method still plays a significant role in protein structure determination. However, this method has become less popular in modern high-throughput oriented crystallography, mostly owing to its trial-and-error nature, which often results in lengthy empirical searches requiring large numbers of well diffracting crystals. In addition, the phasingmore » power of heavy-atom derivatives is often compromised by lack of isomorphism or even loss of diffraction. In order to overcome the difficulties associated with the ‘classical’ heavy-atom derivatization procedure, an attempt has been made to develop a rational crystal-free heavy-atom derivative-screening method and a quick-soak derivatization procedure which allows heavy-atom compound identification. The method includes three basic steps: (i) the selection of likely reactive compounds for a given protein and specific crystallization conditions based on pre-defined heavy-atom compound reactivity profiles, (ii) screening of the chosen heavy-atom compounds for their ability to form protein adducts using mass spectrometry and (iii) derivatization of crystals with selected heavy-metal compounds using the quick-soak method to maximize diffraction quality and minimize non-isomorphism. Overall, this system streamlines the process of heavy-atom compound identification and minimizes the problem of non-isomorphism in phasing.« less
Site specific incorporation of heavy atom-containing unnatural amino acids into proteins for structure determination

DOEpatents

Xie, Jianming [San Diego, CA; Wang, Lei [San Diego, CA; Wu, Ning [Boston, MA; Schultz, Peter G [La Jolla, CA

2008-07-15

Translation systems and other compositions including orthogonal aminoacyl tRNA-synthetases that preferentially charge an orthogonal tRNA with an iodinated or brominated amino acid are provided. Nucleic acids encoding such synthetases are also described, as are methods and kits for producing proteins including heavy atom-containing amino acids, e.g., brominated or iodinated amino acids. Methods of determining the structure of a protein, e.g., a protein into which a heavy atom has been site-specifically incorporated through use of an orthogonal tRNA/aminoacyl tRNA-synthetase pair, are also described.
Study of the heavy atom-induced room temperature phosphorescence properties of melatonin and its analytical application

NASA Astrophysics Data System (ADS)

Amjadi, Mohammad; Manzoori, Jamshid L.; Miller, James N.

2006-02-01

Liquid phase room temperature phosphorescence (RTP) properties of melatonin were studied using heavy atom induced-room temperature phosphorescence (HAI-RTP) technique. 1.2 M potassium iodide was used as a heavy atom reagent together with 0.002 M sodium sulphite as deoxygenating agent to produce the RTP signal. The maximum phosphorescence emission and excitation wavelengths of melatonin were 290 and 457 nm, respectively. The effect of potassium iodide concentration on the RTP lifetime of melatonin was also investigated and based on the results, the rate constants for phosphorescence decay ( kp) and radiationless deactivation through reaction with heavy atom ( kh) were determined. Based on the obtained results, a simple and sensitive room temperature phosphorimetric method was developed for the determination of melatonin. The method allowed the determination of 10.0-200 ng ml -1 melatonin in aqueous solution with the limits of detection and quantification of 3.6 and 12 ng ml -1, respectively. The proposed method was satisfactorily applied to the determination of melatonin in commercial pharmaceutical formulations.
An overview of heavy-atom derivatization of protein crystals

PubMed Central

Pike, Ashley C. W.; Garman, Elspeth F.; Krojer, Tobias; von Delft, Frank; Carpenter, Elisabeth P.

2016-01-01

Heavy-atom derivatization is one of the oldest techniques for obtaining phase information for protein crystals and, although it is no longer the first choice, it remains a useful technique for obtaining phases for unknown structures and for low-resolution data sets. It is also valuable for confirming the chain trace in low-resolution electron-density maps. This overview provides a summary of the technique and is aimed at first-time users of the method. It includes guidelines on when to use it, which heavy atoms are most likely to work, how to prepare heavy-atom solutions, how to derivatize crystals and how to determine whether a crystal is in fact a derivative. PMID:26960118
Automated MAD and MIR structure solution

PubMed Central

Terwilliger, Thomas C.; Berendzen, Joel

1999-01-01

Obtaining an electron-density map from X-ray diffraction data can be difficult and time-consuming even after the data have been collected, largely because MIR and MAD structure determinations currently require many subjective evaluations of the qualities of trial heavy-atom partial structures before a correct heavy-atom solution is obtained. A set of criteria for evaluating the quality of heavy-atom partial solutions in macromolecular crystallography have been developed. These have allowed the conversion of the crystal structure-solution process into an optimization problem and have allowed its automation. The SOLVE software has been used to solve MAD data sets with as many as 52 selenium sites in the asymmetric unit. The automated structure-solution process developed is a major step towards the fully automated structure-determination, model-building and refinement procedure which is needed for genomic scale structure determinations. PMID:10089316
The influence of molecular symmetry and topological factors on the internal heavy atom effect in aromatic and heteroaromatic compounds

NASA Astrophysics Data System (ADS)

Nijegorodov, N.; Mabbs, R.

2001-06-01

The absorption and fluorescence properties of 26 specially selected aromatic and heteroaromatic compounds, from different classes, are studied quantum chemically and experimentally at room temperature (293 K). Seven of these compounds have not been studied before. The compounds are arranged in seven groups, which illustrate different cases of the internal heavy atom effect. The quantum yield of fluorescence, γ and fluorescence decay time, τf of deaerated and non-deaerated cyclohexane or ethanol solutions are measured. The oscillator strength, fe, fluorescence rate constant, kf, natural lifetime, τ0t, and intersystem crossing rate constant, kST, were calculated for each compound. The orbital nature of the lowest excited singlet state and direction of polarization of the S0→ S1 transitions are determined using the PPP-CI method for each molecule. The investigation shows that substitution of a heavy atom(s) (Cl, S, Br, I etc.) into an aromatic or heteroaromatic molecule may produce different changes in all the fluorescence parameters (sometimes dramatically) and not necessarily lead to the quenching of fluorescence. Substitution of a heavy atom(s) may increase the value of the spin-orbit operator, \\Hcirc SO, if the S0→ S1 excitation is localized to some extent on a carbon atom bonded to a heavy atom(s) or on the heavy atom itself (Ö or S). Such substitution may change the symmetry of a molecule and hence the values of the ΨS 1\\HcircsoΨT i' matrix elements would change (in molecules of higher symmetry groups not all Ti states are able to mix with the perturbing S1 state). Such substitution may change the arrangement of Ti states below the S1, state and hence, the Franck-Condon factors would change. Such substitution may also change the value of the ΨS 0M jΨS 1 matrix element and, consequently, the oscillator strength of the S0→ S1 transition would change. A combination of all these possible changes determines the value of kf and kST and, consequently, determines the value of γ and τf. It is observed that in many cases, the value of the spin-orbit operator is related to the dipole moment operator, e.g. if the introduction of a heavy atom increases kST then, as a rule, it decreases fe( 1A→ 1La).
The magic triangle goes MAD: experimental phasing with a bromine derivative

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

Beck, Tobias, E-mail: tbeck@shelx.uni-ac.gwdg.de; Gruene, Tim; Sheldrick, George M.

2010-04-01

5-Amino-2, 4, 6-tribromoisophthalic acid is used as a phasing tool for protein structure determination by MAD phasing. It is the second representative of a novel class of compounds for heavy-atom derivatization that combine heavy atoms with amino and carboxyl groups for binding to proteins. Experimental phasing is an essential technique for the solution of macromolecular structures. Since many heavy-atom ion soaks suffer from nonspecific binding, a novel class of compounds has been developed that combines heavy atoms with functional groups for binding to proteins. The phasing tool 5-amino-2, 4, 6-tribromoisophthalic acid (B3C) contains three functional groups (two carboxylate groups andmore » one amino group) that interact with proteins via hydrogen bonds. Three Br atoms suitable for anomalous dispersion phasing are arranged in an equilateral triangle and are thus readily identified in the heavy-atom substructure. B3C was incorporated into proteinase K and a multiwavelength anomalous dispersion (MAD) experiment at the Br K edge was successfully carried out. Radiation damage to the bromine–carbon bond was investigated. A comparison with the phasing tool I3C that contains three I atoms for single-wavelength anomalous dispersion (SAD) phasing was also carried out.« less
Ab initio effective core potentials including relativistic effects and their application to the electronic structure calculations of heavy atoms and molecules

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

Lee, Y.S.

1977-11-01

The effects of the 4f shell of electrons and the relativity of valence electrons are compared. The effect of 4f shell (lanthanide contraction) is estimated from the numerical Hartree-Fock (HF) calculations of pseudo-atoms corresponding to Hf, Re, Au, Hg, Tl, Pb and Bi without 4f electrons and with atomic numbers reduced by 14. The relativistic effect estimated from the numerical Dirac-Hartree-Fock (DHF) calculations of those atoms is comparable in the magnitude with that of the 4f shell of electrons. Both are larger for 6s than for 5d or 6p electrons. The various relativistic effects on valence electrons are discussed inmore » detail to determine the proper level of the approximation for the valence electron calculations of systems with heavy elements. An effective core potential system has been developed for heavy atoms in which relativistic effects are included in the effective potentials.« less
Determination of the Content of Heavy Metals in Pyrite Contaminated Soil and Plants

PubMed Central

Antonijević, Milan M.; Marić, Miroslava

2008-01-01

Determination of a pyrite contaminated soil texture, content of heavy metals in the soil and soil pH, was the aim in the investigation. Acidification of damaged soil was corrected by calcium carbonate. Mineral nutrients and organic matter (NPK, dung, earthworm cast, straw and coal dust) were added to damaged soil. Afterwards, the soil was used for oat production. Determination of total heavy metal contents (Cu, Pb, Zn, Fe) in soil was performed by atomic absorption spectrofotometry. Plant material (stems, seeds) was analysed, too. Total concentration of the heavy metals in the plant material were greater than in crop obtained in unaffected soil. PMID:27873845
Insights into the Hydrogen-Atom Transfer of the Blue Aroxyl.

PubMed

Bächle, Josua; Marković, Marijana; Kelterer, Anne-Marie; Grampp, Günter

2017-10-19

An experimental and theoretical study on hydrogen-atom transfer dynamics in the hydrogen-bonded substituted phenol/phenoxyl complex of the blue aroxyl (2,4,6-tri-tert-butylphenoxyl) is presented. The experimental exchange dynamics is determined in different organic solvents from the temperature-dependent alternating line-width effect in the continuous-wave ESR spectrum. From bent Arrhenius plots, effective tunnelling contributions with parallel heavy-atom motion are concluded. To clarify the transfer mechanism, reaction paths for different conformers of the substituted phenol/phenoxyl complex are modelled theoretically. Various DFT and post-Hartree-Fock methods including multireference methods are applied. From the comparison of experimental and theoretical data it is concluded that the system favours concerted hydrogen-atom transfer along a parabolic reaction path caused by heavy-atom motion. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Femtosecond response of polyatomic molecules to ultra-intense hard X-rays.

PubMed

Rudenko, A; Inhester, L; Hanasaki, K; Li, X; Robatjazi, S J; Erk, B; Boll, R; Toyota, K; Hao, Y; Vendrell, O; Bomme, C; Savelyev, E; Rudek, B; Foucar, L; Southworth, S H; Lehmann, C S; Kraessig, B; Marchenko, T; Simon, M; Ueda, K; Ferguson, K R; Bucher, M; Gorkhover, T; Carron, S; Alonso-Mori, R; Koglin, J E; Correa, J; Williams, G J; Boutet, S; Young, L; Bostedt, C; Son, S-K; Santra, R; Rolles, D

2017-06-01

X-ray free-electron lasers enable the investigation of the structure and dynamics of diverse systems, including atoms, molecules, nanocrystals and single bioparticles, under extreme conditions. Many imaging applications that target biological systems and complex materials use hard X-ray pulses with extremely high peak intensities (exceeding 10 20 watts per square centimetre). However, fundamental investigations have focused mainly on the individual response of atoms and small molecules using soft X-rays with much lower intensities. Studies with intense X-ray pulses have shown that irradiated atoms reach a very high degree of ionization, owing to multiphoton absorption, which in a heteronuclear molecular system occurs predominantly locally on a heavy atom (provided that the absorption cross-section of the heavy atom is considerably larger than those of its neighbours) and is followed by efficient redistribution of the induced charge. In serial femtosecond crystallography of biological objects-an application of X-ray free-electron lasers that greatly enhances our ability to determine protein structure-the ionization of heavy atoms increases the local radiation damage that is seen in the diffraction patterns of these objects and has been suggested as a way of phasing the diffraction data. On the basis of experiments using either soft or less-intense hard X-rays, it is thought that the induced charge and associated radiation damage of atoms in polyatomic molecules can be inferred from the charge that is induced in an isolated atom under otherwise comparable irradiation conditions. Here we show that the femtosecond response of small polyatomic molecules that contain one heavy atom to ultra-intense (with intensities approaching 10 20 watts per square centimetre), hard (with photon energies of 8.3 kiloelectronvolts) X-ray pulses is qualitatively different: our experimental and modelling results establish that, under these conditions, the ionization of a molecule is considerably enhanced compared to that of an individual heavy atom with the same absorption cross-section. This enhancement is driven by ultrafast charge transfer within the molecule, which refills the core holes that are created in the heavy atom, providing further targets for inner-shell ionization and resulting in the emission of more than 50 electrons during the X-ray pulse. Our results demonstrate that efficient modelling of X-ray-driven processes in complex systems at ultrahigh intensities is feasible.
Femtosecond response of polyatomic molecules to ultra-intense hard X-rays

DOE PAGES

Rudenko, A.; Inhester, L.; Hanasaki, K.; ...

2017-05-31

We report x-ray free-electron lasers enable the investigation of the structure and dynamics of diverse systems, including atoms, molecules, nanocrystals and single bioparticles, under extreme conditions. Many imaging applications that target biological systems and complex materials use hard X-ray pulses with extremely high peak intensities (exceeding 10 20 watts per square centimetre). However, fundamental investigations have focused mainly on the individual response of atoms and small molecules using soft X-rays with much lower intensities. Studies with intense X-ray pulses have shown that irradiated atoms reach a very high degree of ionization, owing to multiphoton absorption, which in a heteronuclear molecularmore » system occurs predominantly locally on a heavy atom (provided that the absorption cross-section of the heavy atom is considerably larger than those of its neighbours) and is followed by efficient redistribution of the induced charge. In serial femtosecond crystallography of biological objects—an application of X-ray free-electron lasers that greatly enhances our ability to determine protein structure—the ionization of heavy atoms increases the local radiation damage that is seen in the diffraction patterns of these objects and has been suggested as a way of phasing the diffraction data. On the basis of experiments using either soft or less-intense hard X-rays, it is thought that the induced charge and associated radiation damage of atoms in polyatomic molecules can be inferred from the charge that is induced in an isolated atom under otherwise comparable irradiation conditions. Here we show that the femtosecond response of small polyatomic molecules that contain one heavy atom to ultra-intense (with intensities approaching 10 20 watts per square centimetre), hard (with photon energies of 8.3 kiloelectronvolts) X-ray pulses is qualitatively different: our experimental and modelling results establish that, under these conditions, the ionization of a molecule is considerably enhanced compared to that of an individual heavy atom with the same absorption cross-section. This enhancement is driven by ultrafast charge transfer within the molecule, which refills the core holes that are created in the heavy atom, providing further targets for inner-shell ionization and resulting in the emission of more than 50 electrons during the X-ray pulse. Fnally, our results demonstrate that efficient modelling of X-ray-driven processes in complex systems at ultrahigh intensities is feasible.« less
Femtosecond response of polyatomic molecules to ultra-intense hard X-rays

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

Rudenko, A.; Inhester, L.; Hanasaki, K.

We report x-ray free-electron lasers enable the investigation of the structure and dynamics of diverse systems, including atoms, molecules, nanocrystals and single bioparticles, under extreme conditions. Many imaging applications that target biological systems and complex materials use hard X-ray pulses with extremely high peak intensities (exceeding 10 20 watts per square centimetre). However, fundamental investigations have focused mainly on the individual response of atoms and small molecules using soft X-rays with much lower intensities. Studies with intense X-ray pulses have shown that irradiated atoms reach a very high degree of ionization, owing to multiphoton absorption, which in a heteronuclear molecularmore » system occurs predominantly locally on a heavy atom (provided that the absorption cross-section of the heavy atom is considerably larger than those of its neighbours) and is followed by efficient redistribution of the induced charge. In serial femtosecond crystallography of biological objects—an application of X-ray free-electron lasers that greatly enhances our ability to determine protein structure—the ionization of heavy atoms increases the local radiation damage that is seen in the diffraction patterns of these objects and has been suggested as a way of phasing the diffraction data. On the basis of experiments using either soft or less-intense hard X-rays, it is thought that the induced charge and associated radiation damage of atoms in polyatomic molecules can be inferred from the charge that is induced in an isolated atom under otherwise comparable irradiation conditions. Here we show that the femtosecond response of small polyatomic molecules that contain one heavy atom to ultra-intense (with intensities approaching 10 20 watts per square centimetre), hard (with photon energies of 8.3 kiloelectronvolts) X-ray pulses is qualitatively different: our experimental and modelling results establish that, under these conditions, the ionization of a molecule is considerably enhanced compared to that of an individual heavy atom with the same absorption cross-section. This enhancement is driven by ultrafast charge transfer within the molecule, which refills the core holes that are created in the heavy atom, providing further targets for inner-shell ionization and resulting in the emission of more than 50 electrons during the X-ray pulse. Fnally, our results demonstrate that efficient modelling of X-ray-driven processes in complex systems at ultrahigh intensities is feasible.« less
Statistical Nature of Atomic Disorder in Irradiated Crystals.

PubMed

Boulle, A; Debelle, A

2016-06-17

Atomic disorder in irradiated materials is investigated by means of x-ray diffraction, using cubic SiC single crystals as a model material. It is shown that, besides the determination of depth-resolved strain and damage profiles, x-ray diffraction can be efficiently used to determine the probability density function (PDF) of the atomic displacements within the crystal. This task is achieved by analyzing the diffraction-order dependence of the damage profiles. We thereby demonstrate that atomic displacements undergo Lévy flights, with a displacement PDF exhibiting heavy tails [with a tail index in the γ=0.73-0.37 range, i.e., far from the commonly assumed Gaussian case (γ=2)]. It is further demonstrated that these heavy tails are crucial to account for the amorphization kinetics in SiC. From the retrieved displacement PDFs we introduce a dimensionless parameter f_{D}^{XRD} to quantify the disordering. f_{D}^{XRD} is found to be consistent with both independent measurements using ion channeling and with molecular dynamics calculations.

Statistical Nature of Atomic Disorder in Irradiated Crystals

NASA Astrophysics Data System (ADS)

Boulle, A.; Debelle, A.

2016-06-01

Atomic disorder in irradiated materials is investigated by means of x-ray diffraction, using cubic SiC single crystals as a model material. It is shown that, besides the determination of depth-resolved strain and damage profiles, x-ray diffraction can be efficiently used to determine the probability density function (PDF) of the atomic displacements within the crystal. This task is achieved by analyzing the diffraction-order dependence of the damage profiles. We thereby demonstrate that atomic displacements undergo Lévy flights, with a displacement PDF exhibiting heavy tails [with a tail index in the γ =0.73 - 0.37 range, i.e., far from the commonly assumed Gaussian case (γ =2 )]. It is further demonstrated that these heavy tails are crucial to account for the amorphization kinetics in SiC. From the retrieved displacement PDFs we introduce a dimensionless parameter fDXRD to quantify the disordering. fDXRD is found to be consistent with both independent measurements using ion channeling and with molecular dynamics calculations.
Localization and orientation of heavy-atom cluster compounds in protein crystals using molecular replacement

PubMed Central

Dahms, Sven O.; Kuester, Miriam; Streb, Carsten; Roth, Christian; Sträter, Norbert; Than, Manuel E.

2013-01-01

Heavy-atom clusters (HA clusters) containing a large number of specifically arranged electron-dense scatterers are especially useful for experimental phase determination of large complex structures, weakly diffracting crystals or structures with large unit cells. Often, the determination of the exact orientation of the HA cluster and hence of the individual heavy-atom positions proves to be the critical step in successful phasing and subsequent structure solution. Here, it is demonstrated that molecular replacement (MR) with either anomalous or isomorphous differences is a useful strategy for the correct placement of HA cluster compounds. The polyoxometallate cluster hexasodium α-metatungstate (HMT) was applied in phasing the structure of death receptor 6. Even though the HA cluster is bound in alternate partially occupied orientations and is located at a special position, its correct localization and orientation could be determined at resolutions as low as 4.9 Å. The broad applicability of this approach was demonstrated for five different derivative crystals that included the compounds tantalum tetradecabromide and trisodium phosphotungstate in addition to HMT. The correct placement of the HA cluster depends on the length of the intramolecular vectors chosen for MR, such that both a larger cluster size and the optimal choice of the wavelength used for anomalous data collection strongly affect the outcome. PMID:23385464
Analysis of heavy metals concentration in water and sediment in the Hara biosphere reserve, southern Iran.

PubMed

Nowrouzi, Mohsen; Mansouri, Borhan; Nabizadeh, Sahar; Pourkhabbaz, Alireza

2014-02-01

This study determined the concentration of heavy metals (Al, Cr, Cu, and Zn) in water and sediments at nine sites in the Hara biosphere reserve of southern Iran during the summer and winter 2010. Determination of Al, Cr, Cu, and Zn in water was carried out by graphite furnace atomic absorption spectrometer (Shimadzu, AA 610s) and in sediment by flame atomic absorption spectrometer (Perkin Elmer, AA3030). Results showed that the heavy metal concentrations in the water samples decreased in the sequence of Zn > Al > Cu > Cr, while in sediment samples were Cr > Zn > Cu > Al. Data analysis indicated that with the exception of Al, there was a Pearson's correlation coefficient between pH and Cu, Zn, and Cr at α = 0.01, 0.05, and 0.001 in sediment (in winter), respectively. There were also significant differences between heavy metals of Cr, Cu, and Zn during the two seasons (p < 0.001) in the water and sediment.
Heavy metals and its chemical speciation in sewage sludge at different stages of processing.

PubMed

Tytła, Malwina; Widziewicz, Kamila; Zielewicz, Ewa

2016-01-01

The analysis of heavy metal concentrations and forms in sewage sludge constitutes an important issue in terms of both health and environmental hazards the metals pose. The total heavy metals concentration enables only the assessment of its contamination. Hence the knowledge of chemical forms is required to determine their environmental mobility and sludge final disposal. Heavy metals speciation was studied by using four-stage sequential extraction BCR (Community Bureau of Reference). This study was aimed at determining the total concentration of selected heavy metals (Zn, Cu, Ni, Pb, Cd, Cr and Hg) and their chemical forms (except for Hg) in sludge collected at different stages of its processing at two municipal Wastewater Treatment Plants in southern Poland. Metals contents in sludge samples were determined by using flame atomic absorption spectrometry (FAAS) and electrothermal atomic absorption spectrometry (ETAAS). This study shows that Zn and Cu appeared to be the most abundant in sludge, while Cd and Hg were in the lowest concentrations. The sewage sludge revealed the domination of immobile fractions over the mobile ones. The oxidizable and residual forms were dominant for all the heavy metals. There was also a significant difference in metals speciation between sludges of different origin which was probably due to differences in wastewater composition and processes occurring in biological stage of wastewater treatment. The results indicate a negligible capability of metals to migrate from sludge into the environment. Our research revealed a significant impact of thickening, stabilization and hygienization on the distribution of heavy metals in sludge and their mobility.
Tetramers of Two Heavy and Two Light Bosons

NASA Astrophysics Data System (ADS)

Naidon, Pascal

2018-07-01

This article considers the bound states of two heavy and two light bosons, when a short-range force attracts the bosons of different mass, and a short-range force repels the light bosons. The existence of such four-body bound states results from the competition between these two forces. For a given strength of the attraction, the critical strength of the repulsion necessary to unbind the four particles is calculated. This study is motivated by the experimental realisation of impurity atoms immersed in an atomic Bose-Einstein condensate, and aims at determining in which regime only one boson contributes to binding two impurities.
Background of the completed research; relevances to solar physics

NASA Technical Reports Server (NTRS)

Sellin, I. A.

1973-01-01

Research activities reported consider the atomic structures of highly stripped heavy ions and their modes of formation and destruction in collisions. The lifetime of the metastable 2 3p1 state of the two electron ion F-7(+) was determined by measuring the radiative decay of an excited helium-like fluorine beam, Metastable state quenching measurements were performed on a helium-like ion to obtain the 1 1S0 to 2 3p2 transition probability. Exponential exchange state dependence of X-ray production cross sections was studied in heavy target atoms during collisions with light charged particles.
Anharmonic Normal Mode Analysis of Elastic Network Model Improves the Modeling of Atomic Fluctuations in Protein Crystal Structures

PubMed Central

Zheng, Wenjun

2010-01-01

Abstract Protein conformational dynamics, despite its significant anharmonicity, has been widely explored by normal mode analysis (NMA) based on atomic or coarse-grained potential functions. To account for the anharmonic aspects of protein dynamics, this study proposes, and has performed, an anharmonic NMA (ANMA) based on the Cα-only elastic network models, which assume elastic interactions between pairs of residues whose Cα atoms or heavy atoms are within a cutoff distance. The key step of ANMA is to sample an anharmonic potential function along the directions of eigenvectors of the lowest normal modes to determine the mean-squared fluctuations along these directions. ANMA was evaluated based on the modeling of anisotropic displacement parameters (ADPs) from a list of 83 high-resolution protein crystal structures. Significant improvement was found in the modeling of ADPs by ANMA compared with standard NMA. Further improvement in the modeling of ADPs is attained if the interactions between a protein and its crystalline environment are taken into account. In addition, this study has determined the optimal cutoff distances for ADP modeling based on elastic network models, and these agree well with the peaks of the statistical distributions of distances between Cα atoms or heavy atoms derived from a large set of protein crystal structures. PMID:20550915
Use of filler limestone and construction and demolition residues for remediating soils contaminated with heavy metals: an assessment by means of plant uptake.

NASA Astrophysics Data System (ADS)

Banegas, Ascension; Martinez-Sanchez, Maria Jose; Agudo, Ines; Perez-Sirvent, Carmen

2010-05-01

A greenhouse trial was carried out to evaluate the assimilation of heavy metals by three types of horticultural plants (lettuce, broccoli and alfalfa), different parts of which are destined for human and animal consumption (leaves, roots, fruits). The plants were cultivated in four types of soil, one uncontaminated (T1), one soil collected in the surrounding area of Sierra Minera (T2), the third being remediated with residues coming from demolition and construction activities (T3) and the four remediated with filler limestone (T4). To determine the metal content, soil samples were first ground to a fine powder using an agate ball mill. Fresh vegetable samples were separated into root and aboveground biomass and then lyophilized. The DTPA-extractable content was also determined to calculate the bioavailable amount of metal. Finally, the translocation factor (TF) and bioconcentration factor (BCF) were calculated. Arsenic levels were obtained by using atomic fluorescence spectrometry with an automated continuous flow hydride generation (HG-AFS) spectrometer and Cd, Pb and Zn was determined by electrothermal atomization atomic absorption spectrometry (ETAAS) or flame atomic absorption spectrometry (FAAS). Samples of the leached water were also obtained and analyzed. According to our results, the retention of the studied elements varies with the type of plant and is strongly decreased by the incorporation of filler limestone and/or construction and demolition residues to the soils. This practice represents a suitable way to reduce the risk posed to the biota by the presence of high levels of heavy metal in soil.
Ionic liquid-based extraction followed by graphite-furnace atomic absorption spectrometry for the determination of trace heavy metals in high-purity iron metal.

PubMed

Matsumiya, Hiroaki; Kato, Tatsuya; Hiraide, Masataka

2014-02-01

The analysis of high-purity materials for trace impurities is an important and challenging task. The present paper describes a facile and sensitive method for the determination of trace heavy metals in high-purity iron metal. Trace heavy metals in an iron sample solution were rapidly and selectively preconcentrated by the extraction into a tiny volume of an ionic liquid [1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide] for the determination by graphite-furnace atomic absorption spectrometry (GFAAS). A nitrogen-donating neutral ligand, 2,4,6-tris(2-pyridyl)-1,3,5-triazine (TPTZ), was found to be effective in the ionic liquid-based selective extraction, allowing the nearly complete (~99.8%) elimination of the iron matrix. The combination with the optimized GFAAS was successful. The detectability reached sub-μg g(-1) levels in iron metal. The novel use of TPTZ in ionic liquid-based extraction followed by GFAAS was successfully applied to the determination of traces of Co, Ni, Cu, Cd, and Pb in certified reference materials for high-purity iron metal. © 2013 Published by Elsevier B.V.
Methodology using a portable X-ray fluorescence device for on-site and rapid evaluation of heavy-atom contamination in wounds: a model study for application to plutonium contamination.

PubMed

Yoshii, Hiroshi; Yanagihara, Kouta; Imaseki, Hitoshi; Hamano, Tsuyoshi; Yamanishi, Hirokuni; Inagaki, Masayo; Sakai, Yasuhiro; Sugiura, Nobuyuki; Kurihara, Osamu; Sakai, Kazuo

2014-01-01

Workers decommissioning the Fukushima-Daiichi nuclear power plant damaged from the Great East Japan Earthquake and resulting tsunami are at risk of injury with possible contamination from radioactive heavy atoms including actinides, such as plutonium. We propose a new methodology for on-site and rapid evaluation of heavy-atom contamination in wounds using a portable X-ray fluorescence (XRF) device. In the present study, stable lead was used as the model contaminant substitute for radioactive heavy atoms. First, the wound model was developed by placing a liquid blood phantom on an epoxy resin wound phantom contaminated with lead. Next, the correlation between the concentration of contaminant and the XRF peak intensity was formulated considering the thickness of blood exiting the wound. Methods to determine the minimum detection limit (MDL) of contaminants at any maximal equivalent dose to the wound by XRF measurement were also established. For example, in this system, at a maximal equivalent dose of 16.5 mSv to the wound and blood thickness of 0.5 mm, the MDL value for lead was 1.2 ppm (3.1 nmol). The radioactivity of 239Pu corresponding to 3.1 nmol is 1.7 kBq, which is lower than the radioactivity of 239Pu contaminating puncture wounds in previous severe accidents. In conclusion, the established methodology could be beneficial for future development of a method to evaluate plutonium contamination in wounds. Highlights: Methodology for evaluation of heavy-atom contamination in a wound was established. A portable X-ray fluorescence device enables on-site, rapid and direct evaluation. This method is expected to be used for evaluation of plutonium contamination in wounds.
Determination of trace and heavy metals in some commonly used medicinal herbs in Ayurveda.

PubMed

Nema, Neelesh K; Maity, Niladri; Sarkar, Birendra K; Mukherjee, Pulok K

2014-11-01

Traditionally, the herbal drugs are well established for their therapeutic benefits. Depending upon their geographical sources sometimes the trace and heavy metals' content may differ, which may lead to severe toxicity. So, the toxicological and safety assessment of these herbal drugs are one of the major issues in recent days. Eight different plant species including Aloe vera, Centella asiatica, Calendula officinalis, Cucumis sativus, Camellia sinensis, Clitoria ternatea, Piper betel and Tagetes erecta were selected to determine their heavy and trace metals content and thereby to assure their safer therapeutic application. The trace and heavy metals were detected through atomic absorption spectrometry analysis. The selected medicinal plant materials were collected from the local cultivated regions of West Bengal, India, and were digested with nitric acid and hydrochloric acid as specified. Absorbance was measured through atomic absorption spectrometer (AA 303) and the concentration of different trace and heavy metals in the plant samples were calculated. The quantitative determinations were carried out using standard calibration curve obtained by the standard solutions of different metals. The contents of heavy metals were found to be within the prescribed limit. Other trace metals were found to be present in significant amount. Thus, on the basis of experimental outcome, it can be concluded that the plant materials collected from the specific region are safe and may not produce any harmful effect of metal toxicity during their therapeutic application. The investigated medicinal plants contain trace metals such as copper (Cu), chromium (Cr), manganese (Mn), iron (Fe) and nickel (Ni) as well as heavy metals such as arsenic (As), lead (Pb) and mercury (Hg), which were present within the permissible limit. © The Author(s) 2012.
Fast calculator for X-ray emission due to Radiative Recombination and Radiative Electron Capture in relativistic heavy-ion atom collisions

NASA Astrophysics Data System (ADS)

Herdrich, M. O.; Weber, G.; Gumberidze, A.; Wu, Z. W.; Stöhlker, Th.

2017-10-01

In experiments with highly charged, fast heavy ions the Radiative Recombination (RR) and Radiative Electron Capture (REC) processes have significant cross sections in an energy range of up to a few GeV / u . They are some of the most important charge changing processes in collisions of heavy ions with atoms and electrons, leading to the emission of a photon along with the formation of the ground and excited atomic states. Hence, for the understanding and planning of experiments, in particular for X-ray spectroscopy studies, at accelerator ring facilities, such as FAIR, it is crucial to have a good knowledge of these cross sections and the associated radiation characteristics. In the frame of this work a fast calculator, named RECAL, for the RR and REC process is presented and its capabilities are demonstrated with the analysis of a recently conducted experiment at the Experimental Storage Ring (ESR) at the GSI Helmholtz Center for Heavy Ion Research in Darmstadt, Germany. A method is presented to determine unknown X-ray emission cross sections via normalization of the recorded spectra to REC cross sections calculated by RECAL.
The heavy atom microwave structure of 2-methyltetrahydrofuran

NASA Astrophysics Data System (ADS)

Van, Vinh; Stahl, Wolfgang; Nguyen, Ha Vinh Lam

2016-11-01

The rotational spectra of 2-methyltetrahydrofuran have been observed using a pulsed molecular beam Fourier transform microwave spectrometer operating in the frequency range 2-26.5 GHz. Conformational analysis using quantum chemical calculations yields two stable conformers; both of them possess an envelope structure. The conformational transformation can occur via two different transition states. The Cremer-Pople notation for five-membered rings is chosen for describing the conformations. Only one conformer with equatorial position of the methyl group is assigned in the experimental spectrum. The fits of its parent species, 13C- and 18O-isotopologues result in highly accurate molecular parameters, and enable the determination of a heavy atom rs structure using Kraitchman's equations. This experimentally determined structure is in excellent agreement with the structure calculated by anharmonic frequency calculations.
The UKB prescription and the heavy atom effects on the nuclear magnetic shielding of vicinal heavy atoms.

PubMed

Maldonado, Alejandro F; Aucar, Gustavo A

2009-07-21

Fully relativistic calculations of NMR magnetic shielding on XYH3 (X = C, Si, Ge and Sn; Y = Br, I), XHn (n = 1-4) molecular systems and noble gases performed with a fully relativistic polarization propagator formalism at the RPA level of approach are presented. The rate of convergence (size of basis set and time involved) for calculations with both kinetic balance prescriptions, RKB and UKB, were investigated. Calculations with UKB makes it feasible to obtain reliable results for two or more heavy-atom-containing molecules. For such XYH3 systems, the influence of heavy vicinal halogen atoms on sigma(X) is such that heavy atom effects on heavy atoms (vicinal plus their own effects or HAVHA + HAHA effects) amount to 30.50% for X = Sn and Y = I; being the HAHA effect of the order of 25%. So the vicinal effect alone is of the order of 5.5%. The vicinal heavy atom effect on light atoms (HALA effect) is of the order of 28% for X = C and Y = I. A similar behaviour, but of opposite sign, is observed for sigma(Y) for which sigmaR-NR (I; X = C) (HAHA effect) is around 27% and sigmaR-NR(I; X = Sn) (HAVHA + HAHA effects) is close to 21%. Its electronic origin is paramagnetic for halogen atoms but both dia- and paramagnetic for central atoms. The effect on two bond distant hydrogen atoms is such that the largest variation of sigma(H) within the same family of XYH3 molecules appears for X = Si and Y = I: around 20%. In this case sigma(H; X = Sn, Y = I) = 33.45 ppm and sigma(H; X = Sn, Y = H) = 27.82 ppm.
Semi-empirical studies of atomic structure. Progress report, 1 July 1982-1 February 1983

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

Curtis, L.J.

1983-01-01

A program of studies of the properties of the heavy and highly ionized atomic systems which often occur as contaminants in controlled fusion devices is continuing. The project combines experimental measurements by fast-ion-beam excitation with semi-empirical data parametrizations to identify and exploit regularities in the properties of these very heavy and very highly ionized systems. The increasing use of spectroscopic line intensities as diagnostics for determining thermonuclear plasma temperatures and densities requires laboratory observation and analysis of such spectra, often to accuracies that exceed the capabilities of ab initio theoretical methods for these highly relativistic many electron systems. Through themore » acquisition and systematization of empirical data, remarkably precise methods for predicting excitation energies, transition wavelengths, transition probabilities, level lifetimes, ionization potentials, core polarizabilities, and core penetrabilities are being developed and applied. Although the data base for heavy, highly ionized atoms is still sparse, parametrized extrapolations and interpolations along isoelectronic, homologous, and Rydberg sequences are providing predictions for large classes of quantities, with a precision that is sharpened by subsequent measurements.« less
Semiempirical studies of atomic structure. Progress report, 1 July 1983-1 June 1984

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

Curtis, L.J.

1984-01-01

A program of studies of the properties of the heavy and highly ionized atomic systems which often occur as contaminants in controlled fusion devices is continuing. The project combines experimental measurements by fast ion beam excitation with semiempirical data parametrizations to identify and exploit regularities in the properties of these very heavy and very highly ionized systems. The increasing use of spectroscopic line intensities as diagnostics for determining thermonuclear plasma temperatures and densities requires laboratory observation and analysis of such spectra, often to accuracies that exceed the capabilities of ab initio theoretical methods for these highly relativistic many electron systems.more » Through the acquisition and systematization of empirical data, remarkably precise methods for predicting excitation energies, transition wavelengths, transition probabilities, level lifetimes, ionization potentials, core polarizabilities, and core penetrabilities are being developed and applied. Although the data base for heavy, highly ionized atoms is still sparse, parametrized extrapolations and interpolations along isoelectronic, homologous, and Rydberg sequences are providing predictions for large classes of quantities, with a precision that is sharpened by subsequent measurements.« less
How Kondo-holes create intense nanoscale heavy-fermion hybridization disorder

PubMed Central

Hamidian, Mohammad H.; Schmidt, Andrew R.; Firmo, Inês A.; Allan, Milan P.; Bradley, Phelim; Garrett, Jim D.; Williams, Travis J.; Luke, Graeme M.; Dubi, Yonatan; Balatsky, Alexander V.; Davis, J. C.

2011-01-01

Replacing a magnetic atom by a spinless atom in a heavy-fermion compound generates a quantum state often referred to as a “Kondo-hole”. No experimental imaging has been achieved of the atomic-scale electronic structure of a Kondo-hole, or of their destructive impact [Lawrence JM, et al. (1996) Phys Rev B 53:12559–12562] [Bauer ED, et al. (2011) Proc Natl Acad Sci. 108:6857–6861] on the hybridization process between conduction and localized electrons which generates the heavy-fermion state. Here we report visualization of the electronic structure at Kondo-holes created by substituting spinless thorium atoms for magnetic uranium atoms in the heavy-fermion system URu2Si2. At each thorium atom, an electronic bound state is observed. Moreover, surrounding each thorium atom we find the unusual modulations of hybridization strength recently predicted to occur at Kondo-holes [Figgins J, Morr DK (2011) Phys Rev Lett 107:066401]. Then, by introducing the “hybridization gapmap” technique to heavy-fermion studies, we discover intense nanoscale heterogeneity of hybridization due to a combination of the randomness of Kondo-hole sites and the long-range nature of the hybridization oscillations. These observations provide direct insight into both the microscopic processes of heavy-fermion forming hybridization and the macroscopic effects of Kondo-hole doping. PMID:22006302
Assessment of radioactive materials and heavy metals in the surface soil around uranium mining area of Tongliao, China.

PubMed

Haribala; Hu, Bitao; Wang, Chengguo; Gerilemandahu; Xu, Xiao; Zhang, Shuai; Bao, Shanhu; Li, Yuhong

2016-08-01

Natural and artificial radionuclides and heavy metals in the surface soil of the uranium mining area of Tongliao, China, were measured using gamma spectrometry, flame atomic absorption spectrophotometry, graphite furnace atomic absorption spectrophotometry and microwave dissolution atomic fluorescence spectrometry respectively. The estimated average activity concentrations of (238)U, (232)Th, (226)Ra, (40)K and (137)Cs are 27.53±16.01, 15.89±5.20, 12.64±4.27, 746.84±38.24 and 4.23±4.76Bq/kg respectively. The estimated average absorbed dose rate in the air and annual effective dose rate are 46.58±5.26nGy/h and 57.13±6.45μSv, respectively. The radium equivalent activity, external and internal hazard indices were also calculated and their mean values are within the acceptable limits. The heavy metal concentrations of Pb, Cd, Cu, Zn, Hg and As from the surface soil were measured and their health risks were then determined. Although the content of Cd is much higher than the average background in China, its non-cancer and cancer risk indices are all within the acceptable ranges. These calculated hazard indices to estimate the potential radiological health risk in soil and the dose rate are well below their permissible limit. In addition the correlations between the radioactivity concentrations of the radionuclides and the heavy metals in soil were determined by the Pearson linear coefficient. Copyright © 2016 Elsevier Inc. All rights reserved.
The Influence of a Presence of a Heavy Atom on (13)C Shielding Constants in Organomercury Compounds and Halogen Derivatives.

PubMed

Wodyński, Artur; Gryff-Keller, Adam; Pecul, Magdalena

2013-04-09

(13)C nuclear magnetic resonance shielding constants have been calculated by means of density functional theory (DFT) for several organomercury compounds and halogen derivatives of aliphatic and aromatic compounds. Relativistic effects have been included through the four-component Dirac-Kohn-Sham (DKS) method, two-component Zeroth Order Regular Approximation (ZORA) DFT, and DFT with scalar effective core potentials (ECPs). The relative shieldings have been analyzed in terms of the position of carbon atoms with respect to the heavy atom and their hybridization. The results have been compared with the experimental values, some newly measured and some found in the literature. The main aim of the calculations has been to evaluate the magnitude of heavy atom effects on the (13)C shielding constants and to check what are the relative contributions of scalar relativistic effects and spin-orbit coupling. Another object has been to compare the DKS and ZORA results and to check how the approximate method of accounting for the heavy-atom-on-light-atom (HALA) relativistic effect by means of scalar effective core potentials on heavy atoms performs in comparison with the more rigorous two- and four-component treatment.
Enhanced Reverse Saturable Absorption and Optical Limiting in Heavy-Atom Substituted Phthalocyanines

NASA Technical Reports Server (NTRS)

Perry, J. W.; Mansour, K.; Marder, S. R.; Alvarez, D., Jr.; Perry, K. J.; Choong, I.

1994-01-01

The reverse saturable absorption and optical limiting response of metal phthalocyaninies can be enhanced by using the heavy-atom effect. Phthalocyanines containing heavy metal atoms, such as In, Sn, and Pb show nearly a factor of two enhancement in the ratio of effective excited-state to ground-state absorption cross sections compared to those containing lighter atoms, such as Al and Si. In an f/8 optical geometry, homogeneous solutions of heavy metal phthalocyanines, at 30% linear transmission, limit 8-ns, 532-nm laser pulses to less than or equal to 3 (micro)J (the energy for 50% probability of eye damage) for incident pulses up to 800 (micro)J.

Selected toxic and essential heavy metals in impacted teeth and the surrounding mandibular bones of people exposed to heavy metals in the environment.

PubMed

Malara, Piotr; Fischer, Agnieszka; Malara, Beata

2016-01-01

The elemental composition of bones and teeth can allow exposure to heavy metals in the environment to be estimated. The aim of this study was to determine whether impacted mandibular teeth and the surrounding bones can be used as biomonitoring media to assess exposure to heavy metals. The research materials were 67 impacted lower third molars and samples of the cortical bone removed when the wisdom teeth were surgically extracted. The samples were from people living in two areas with different environmental concentrations of heavy metals. The cadmium, chromium, copper, iron, lead, manganese, and zinc concentrations in the samples were determined by atomic absorption spectrometry with flame atomization. The cadmium and lead concentrations in the impacted third molars and the bones surrounding the teeth were significantly higher for people living in the relatively polluted Ruda Slaska region than for people living in Bielsko-Biala region. Significantly higher chromium, copper, manganese, and zinc concentrations were found in the bones surrounding the impacted teeth from people living in Ruda Slaska than in the bones surrounding the impacted teeth from people living in Bielsko-Biala. The cadmium concentrations in impacted teeth and the surrounding bones were significantly positively correlated. The results indicated that impacted mandibular teeth and the surrounding mandibular bones may reflect the exposure of people to cadmium and lead in the environment. This conclusion, however, must be verified in future research projects designed to exclude the possibility of additional dietary, occupational, and other types of exposure to heavy metals.
[Determination of metal elements in Achyranthis bidentatae radix from various habitats].

PubMed

Tu, Wan-Qian; Zhang, Liu-Ji

2011-12-01

To establish an atomic absorption spectrometry method for determination of the contents of metal elements in Achyranthis Bidentatae Radix and analyze 21 batches of samples from different areas. Fe, Mn, Ca, Mg, K, Zn and Cu were detected by atomic absorption spectrometry with hydrogen flame detector, Pb, As and Cd were detected by graphite furnace atomic absorption, Hg was detected by cold atomic absorption. The heavy metal contents met the requirement of Chinese Pharmacopoeia. The contents of K, Mg, Cu and Mn in the samples of geo-authentic areas were higher,while the contents of Fe, Zn, Hg and Pb in the samples of non-authentic areas were higher. This method is sample, accurate, repeatable and could be used to evaluate the quality of Achyranthis Bidentatae Radix.
Use of scleractinian corals to indicate marine pollution in the northern Gulf of Aqaba, Jordan.

PubMed

Barakat, S A; Al-Rousan, S; Al-Trabeen, M S

2015-02-01

The actual and fatal concentrations of selected heavy metals, including cadmium, cobalt, copper, lead, nickel, and zinc in corals from the Gulf of Aqaba were determined. Several living coral samples of different species (e.g., Porites) were collected from shallow depths (of about 5 m) at a number of sites along the Jordanian Gulf of Aqaba coast. The coral samples were collected using either a pneumatic diamond drill corer (for Porites) or a hammer and chisel (for other branched species). Some of the corals that had been collected were analyzed for heavy metals using atomic absorption spectrometry, and other samples were used in incubation experiments. The heavy metal concentrations were determined separately in the coral skeleton and the tissue layer. Heavy metal concentrations have not previously been determined in corals from the Gulf of Aqaba. We conclude that corals are suitable for use as proxy tools for assessing environmental pollution (i.e., they are bioindicators) in the Gulf of Aqaba and the Red Sea. Therefore, this study provides useful information on the degree of heavy metal contamination in the study area.
The Shape and Flow of Heavy Ion Collisions (490th Brookhaven Lecture)

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

Schenke, Bjoern

2014-12-18

The sun can’t do it, but colossal machines like the Relativistic Heavy Ion Collider (RHIC) at Brookhaven Lab and Large Hadron Collider (LHC) in Europe sure can. Quarks and gluons make up protons and neutrons found in the nucleus of every atom in the universe. At heavy ion colliders like RHIC and the LHC, scientists can create matter more than 100,000 times hotter than the center of the sun—so hot that protons and neutrons melt into a plasma of quarks and gluons. The particle collisions and emerging quark-gluon plasma hold keys to understanding how these fundamental particles interact with eachmore » other, which helps explain how everything is held together—from atomic nuclei to human beings to the biggest stars—how all matter has mass, and what the universe looked like microseconds after the Big Bang. Dr. Schenke discusses theory that details the shape and structure of heavy ion collisions. He will also explain how this theory and data from experiments at RHIC and the LHC are being used to determine properties of the quark-gluon plasma.« less
HIAF: New opportunities for atomic physics with highly charged heavy ions

NASA Astrophysics Data System (ADS)

Ma, X.; Wen, W. Q.; Zhang, S. F.; Yu, D. Y.; Cheng, R.; Yang, J.; Huang, Z. K.; Wang, H. B.; Zhu, X. L.; Cai, X.; Zhao, Y. T.; Mao, L. J.; Yang, J. C.; Zhou, X. H.; Xu, H. S.; Yuan, Y. J.; Xia, J. W.; Zhao, H. W.; Xiao, G. Q.; Zhan, W. L.

2017-10-01

A new project, High Intensity heavy ion Accelerator Facility (HIAF), is currently being under design and construction in China. HIAF will provide beams of stable and unstable heavy ions with high energies, high intensities and high quality. An overview of new opportunities for atomic physics using highly charged ions and radioactive heavy ions at HIAF is given.
Heavy Metals Resisting Gravity in White Dwarfs?

NASA Astrophysics Data System (ADS)

Rauch, T.; Gamrath, S.; Quinet, P.; Hoyer, D.; Werner, K.; Kruk, J. W.

2017-03-01

Spectral lines of heavy metals, identified in high-resolution ultraviolet spectra of the DO-type white dwarf RX J0503.9-2854 (RE 0503-289), allow precise abundance determinations of these species by means of advanced non-local thermodynamic equilibrium stellar-atmosphere models - provided that reliable atomic data is available. Such analyses of Zn (atomic number Z = 30), Ga (31), Ge (32), As (33), Mo (42), Kr (36), Zr (40), Xe (54), and Ba (56) have recently shown that, without exception, their abundances are unexpectedly strongly supersolar (up to about 5 dex). This is much higher than predicted by recent asymptotic giant branch nucleosynthesis calculations. Thus, the interplay of gravitational settling and radiative levitation may play an important role for their photospheric prominence.
Heavy Metals Resisting Gravity in White Dwarfs?

NASA Technical Reports Server (NTRS)

Rauch, Thomas; Gamrath, Sebastien; Quinet, Pascal; Hoyer, Denny; Werner, Klaus; Kruk, Jeffrey Walter

2017-01-01

Spectral lines of heavy metals, identified in high-resolution ultraviolet spectra of the DO-type white dwarf RX J0503.9-2854 (RE 0503-289), allow precise abundance determinations of these species by means of advanced non-local thermo-dynamic equilibrium stellar-atmosphere models provided that reliable atomic data is available. Such analyses of Zn (atomic number Z equals 30), Ga (31), Ge (32), As (33), Mo(42), Kr (36), Zr (40), Xe (54), and Ba (56) have recently shown that, without exception, their abundances are unexpectedly strongly supersolar (up to about 5 dex (decimal exponent)). This is much higher than predicted by recent asymptotic giant branch nucleosynthesis calculations. Thus, the interplay of gravitational settling and radiative levitation may play an important role for their photospheric prominence.
High-energy accelerator for beams of heavy ions

DOEpatents

Martin, Ronald L.; Arnold, Richard C.

1978-01-01

An apparatus for accelerating heavy ions to high energies and directing the accelerated ions at a target comprises a source of singly ionized heavy ions of an element or compound of greater than 100 atomic mass units, means for accelerating the heavy ions, a storage ring for accumulating the accelerated heavy ions and switching means for switching the heavy ions from the storage ring to strike a target substantially simultaneously from a plurality of directions. In a particular embodiment the heavy ion that is accelerated is singly ionized hydrogen iodide. After acceleration, if the beam is of molecular ions, the ions are dissociated to leave an accelerated singly ionized atomic ion in a beam. Extraction of the beam may be accomplished by stripping all the electrons from the atomic ion to switch the beam from the storage ring by bending it in magnetic field of the storage ring.
Development of online, continuous heavy metals detection and monitoring sensors based on microfluidic plasma reactors

NASA Astrophysics Data System (ADS)

Abdul-Majeed, Wameath Sh

This research is dedicated to develop a fully integrated system for heavy metals determination in water samples based on micro fluidic plasma atomizers. Several configurations of dielectric barrier discharge (DBD) atomizer are designed, fabricated and tested toward this target. Finally, a combination of annular and rectangular DBD atomizers has been utilized to develop a scheme for heavy metals determination. The present thesis has combined both theoretical and experimental investigations to fulfil the requirements. Several mathematical studies are implemented to explore the optimal design parameters for best system performance. On the other hand, expanded experimental explorations are conducted to assess the proposed operational approaches. The experiments were designed according to a central composite rotatable design; hence, an empirical model has been produced for each studied case. Moreover, several statistical approaches are adopted to analyse the system performance and to deduce the optimal operational parameters.. The introduction of the examined analyte to the plasma atomizer has been achieved by applying chemical schemes, where the element in the sample has been derivitized by using different kinds of reducing agents to produce vapour species (e.g. hydrides) for a group of nine elements examined in this research individually and simultaneously. Moreover, other derivatization schemes based on photochemical vapour generation assisted by ultrasound irradiation are also investigated. Generally speaking, the detection limits achieved in this research for the examined set of elements (by applying hydroborate scheme) are found to be acceptable in accordance with the standard limits in drinking water. The results of copper compared with the data from other technologies in the literature, showed a competitive detection limit obtained from applying the developed scheme, with an advantage of conducting simultaneous, fully automated, insitu, online- real time analysis as well as a possibility of connecting the proposed device to control loops..
Flawed Nuclear Physics and Atomic Intelligence in the Campaign to deny Norwegian Heavy Water to Germany, 1942-1944

NASA Astrophysics Data System (ADS)

Børresen, Hans Christofer

2012-12-01

The military campaign to deny Norwegian heavy water to Germany in World War II did not diminish as the threat posed by heavy water in German hands dwindled, mainly because of excessive security among the Allies. Signs that Albert Speer (1905-1981) had decided in 1942 to stop the German atomic-bomb project were kept secret and ignored. Prominent Allied advisers like Leif Tronstad (1903-1945) and even Niels Bohr (1885-1962) were not told about the plutonium path to a German atomic bomb. Physicists did not brief advisers, decision makers, and Allied officers on how many years Werner Heisenberg (1901-1976) would need to accumulate enough heavy water (deuterium oxide, D2O) for an Uranmachine and then to extract and process plutonium for an atomic bomb. Had the flow of information been better, the military raids on the Norwegian heavy-water plant at Vemork could have been timed better, and the more costly of them could have been averted altogether.
Environmental impact of the gold mining industry in Ghana.

PubMed

Bamford, S A; Osae, E; Aboh, I; Biney, C A; Antwi, L A

1990-01-01

X-ray Fluorescence (XRF) Analysis and Atomic Absorption Spectrophotometry (AAS) have been used in assessing heavy metal pollution from some gold mines in Ghana. The presence and levels of heavy metals in gold ore, gold tailings, inland waters, and river sediments have been determined. Using these techniques, the heavy metals: Cr, Mn, Fe, Cu, Zn, As, Pb, Rb, Sr, Y, Zr, and Nb were identified in some of the solid samples within a concentration range of 0.08 ppm--4.9%. However, the inland waters showed the presence of only Fe and Zn at levels of 0.08-2.4 micrograms/mL.
Phasing and structure of bestrophin-1: a case study in the use of heavy-atom cluster compounds with multi-subunit transmembrane proteins

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

Kane Dickson, Veronica

The purification and three-dimensional crystallization of membrane proteins are commonly affected by a cumulation of pathologies that are less prevalent in their soluble counterparts. This may include severe anisotropy, poor spot shape, poor to moderate-resolution diffraction, crystal twinning, translational pseudo-symmetry and poor uptake of heavy atoms for derivatization. Such challenges must be circumvented by adaptations in the approach to crystallization and/or phasing. Here, an example of a protein that exhibited all of the above-mentioned complications is presented. Bestrophin-1 is a eukaryotic calcium-activated chloride channel, the structure of which was recently determined in complex with monoclonal antibody fragments using SAD phasingmore » with tantalum bromide clusters (Ta 6Br 12·Br 2). Some of the obstacles to obtaining improved diffraction and phasing for this particular channel are discussed, as well as the approach and adaptations that were key to determining the structure.« less
Hydrogen atoms can be located accurately and precisely by x-ray crystallography.

PubMed

Woińska, Magdalena; Grabowsky, Simon; Dominiak, Paulina M; Woźniak, Krzysztof; Jayatilaka, Dylan

2016-05-01

Precise and accurate structural information on hydrogen atoms is crucial to the study of energies of interactions important for crystal engineering, materials science, medicine, and pharmacy, and to the estimation of physical and chemical properties in solids. However, hydrogen atoms only scatter x-radiation weakly, so x-rays have not been used routinely to locate them accurately. Textbooks and teaching classes still emphasize that hydrogen atoms cannot be located with x-rays close to heavy elements; instead, neutron diffraction is needed. We show that, contrary to widespread expectation, hydrogen atoms can be located very accurately using x-ray diffraction, yielding bond lengths involving hydrogen atoms (A-H) that are in agreement with results from neutron diffraction mostly within a single standard deviation. The precision of the determination is also comparable between x-ray and neutron diffraction results. This has been achieved at resolutions as low as 0.8 Å using Hirshfeld atom refinement (HAR). We have applied HAR to 81 crystal structures of organic molecules and compared the A-H bond lengths with those from neutron measurements for A-H bonds sorted into bonds of the same class. We further show in a selection of inorganic compounds that hydrogen atoms can be located in bridging positions and close to heavy transition metals accurately and precisely. We anticipate that, in the future, conventional x-radiation sources at in-house diffractometers can be used routinely for locating hydrogen atoms in small molecules accurately instead of large-scale facilities such as spallation sources or nuclear reactors.
Hydrogen atoms can be located accurately and precisely by x-ray crystallography

PubMed Central

Woińska, Magdalena; Grabowsky, Simon; Dominiak, Paulina M.; Woźniak, Krzysztof; Jayatilaka, Dylan

2016-01-01

Precise and accurate structural information on hydrogen atoms is crucial to the study of energies of interactions important for crystal engineering, materials science, medicine, and pharmacy, and to the estimation of physical and chemical properties in solids. However, hydrogen atoms only scatter x-radiation weakly, so x-rays have not been used routinely to locate them accurately. Textbooks and teaching classes still emphasize that hydrogen atoms cannot be located with x-rays close to heavy elements; instead, neutron diffraction is needed. We show that, contrary to widespread expectation, hydrogen atoms can be located very accurately using x-ray diffraction, yielding bond lengths involving hydrogen atoms (A–H) that are in agreement with results from neutron diffraction mostly within a single standard deviation. The precision of the determination is also comparable between x-ray and neutron diffraction results. This has been achieved at resolutions as low as 0.8 Å using Hirshfeld atom refinement (HAR). We have applied HAR to 81 crystal structures of organic molecules and compared the A–H bond lengths with those from neutron measurements for A–H bonds sorted into bonds of the same class. We further show in a selection of inorganic compounds that hydrogen atoms can be located in bridging positions and close to heavy transition metals accurately and precisely. We anticipate that, in the future, conventional x-radiation sources at in-house diffractometers can be used routinely for locating hydrogen atoms in small molecules accurately instead of large-scale facilities such as spallation sources or nuclear reactors. PMID:27386545
Effect of heavy atoms on photochemically induced dynamic nuclear polarization in liquids

NASA Astrophysics Data System (ADS)

Okuno, Yusuke; Cavagnero, Silvia

2018-01-01

Given its short hyperpolarization time (∼10-6 s) and mostly non-perturbative nature, photo-chemically induced dynamic nuclear polarization (photo-CIDNP) is a powerful tool for sensitivity enhancement in nuclear magnetic resonance. In this study, we explore the extent of 1H-detected 13C nuclear hyperpolarization that can be gained via photo-CIDNP in the presence of small-molecule additives containing a heavy atom. The underlying rationale for this methodology is the well-known external-heavy-atom (EHA) effect, which leads to significant enhancements in the intersystem-crossing rate of selected photosensitizer dyes from photoexcited singlet to triplet. We exploited the EHA effect upon addition of moderate amounts of halogen-atom-containing cosolutes. The resulting increase in the transient triplet-state population of the photo-CIDNP sensitizer fluorescein resulted in a significant increase in the nuclear hyperpolarization achievable via photo-CIDNP in liquids. We also explored the internal-heavy-atom (IHA) effect, which is mediated by halogen atoms covalently incorporated into the photosensitizer dye. Widely different outcomes were achieved in the case of EHA and IHA, with EHA being largely preferable in terms of net hyperpolarization.
Faculty Member for Research in an Undergraduate Institution Prize Talk: Research and Teaching through high-precision spectroscopy of heavy atoms

NASA Astrophysics Data System (ADS)

Majumder, Tiku

2017-04-01

In recent decades, substantial experimental effort has centered on heavy (high-Z) atomic and molecular systems for atomic-physics-based tests of standard model physics, through (for example) measurements of atomic parity nonconservation and searches for permanent electric dipole moments. In all of this work, a crucial role is played by atomic theorists, whose accurate wave function calculations are essential in connecting experimental observables to tests of relevant fundamental physics parameters. At Williams College, with essential contributions from dozens of undergraduate students, we have pursued a series of precise atomic structure measurements in heavy metal atoms such as thallium, indium, and lead. These include measurements of hyperfine structure, transition amplitudes, and atomic polarizability. This work, involving diode lasers, heated vapor cells, and an atomic beam apparatus, has both tested the accuracy and helped guide the refinement of new atomic theory calculations. I will discuss a number of our recent experimental results, emphasizing the role played by students and the opportunities that have been afforded for research-training in this undergraduate environment. Work supported by Research Corporation, the NIST Precision Measurement Grants program, and the National Science Foundation.
Sensitized and heavy atom induced production of acenaphthylene triplet: A laser flash photolysis study

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

Samanta, A.; Fessenden, R.W.

1989-07-27

The triplet state of acenaphthylene has been examined by nanosecond laser flash photolysis using sensitization and heavy atom perturbation techniques. Although acenaphthylene does not form any observable triplet upon direct flash excitation, a transient with microsecond lifetime ({lambda}{sub max} = 315 nm) is observable when a solution of the sample is excited by sensitizers (benzophenone, thioxanthone, benzil). This transient is ascribed to the triplet of acenaphthylene on the basis of its quenching behavior toward oxygen, ferrocene, azulene, and {beta}-carotene. Quantitative data concerning the triplet-triplet absorption and quenching constants are presented. The triplet energy is estimated to lie between 46 andmore » 47 kcal/mol. The triplet can also be produced by direct excitation in solvents containing heavy atoms (ethyl bromide, ethyl iodide). The triplet yield is found to increase with an increase of the amount of the heavy atom containing solvent. No saturation limit is obtained. These facts together with the effect of heavy atoms on the T{sub 1} {yields} S{sub 0} process allow the differing behavior of ethyl bromide and ethyl iodide on the photodimerization process of acenaphthylene to be explained. Triplet-state parameters (extinction coefficient and triplet yield) have been estimated in these solvents by the energy-transfer technique and actinometry.« less
Accurate Determination of the Dynamical Polarizability of Dysprosium

NASA Astrophysics Data System (ADS)

Ravensbergen, C.; Corre, V.; Soave, E.; Kreyer, M.; Tzanova, S.; Kirilov, E.; Grimm, R.

2018-06-01

We report a measurement of the dynamical polarizability of dysprosium atoms in their electronic ground state at the optical wavelength of 1064 nm, which is of particular interest for laser trapping experiments. Our method is based on collective oscillations in an optical dipole trap, and reaches unprecedented accuracy and precision by comparison with an alkali atom (potassium) as a reference species. We obtain values of 184.4(2.4) and 1.7(6) a.u. for the scalar and tensor polarizability, respectively. Our experiments have reached a level that permits meaningful tests of current theoretical descriptions and provides valuable information for future experiments utilizing the intriguing properties of heavy lanthanide atoms.
Source apportionment of atmospheric bulk deposition in the Belgrade urban area using Positive Matrix factorization

NASA Astrophysics Data System (ADS)

Tasić, M.; Mijić, Z.; Rajšić, S.; Stojić, A.; Radenković, M.; Joksić, J.

2009-04-01

The primary objective of the present study was to assess anthropogenic impacts of heavy metals to the environment by determination of total atmospheric deposition of heavy metals. Atmospheric depositions (wet + dry) were collected monthly, from June 2002 to December 2006, at three urban locations in Belgrade, using bulk deposition samplers. Concentrations of Fe, Al, Pb, Zn, Cu, Ni, Mn, Cr, V, As and Cd were analyzed using atomic absorption spectrometry. Based upon these results, the study attempted to examine elemental associations in atmospheric deposition and to elucidate the potential sources of heavy metal contaminants in the region by the use of multivariate receptor model Positive Matrix Factorization (PMF).
Heavy metals in red crabs, Chaceon quinquedens, from the Gulf of Mexico.

PubMed

Perry, Harriet; Isphording, Wayne; Trigg, Christine; Riedel, Ralf

2015-12-30

The red crab, Chaceon quinquedens, is distributed in deep waters of the Gulf of Mexico (GOM) and is most abundant in an area associated with sediment deposition from the Mississippi River. Sediment geochemistry and biological and ecological traits of red crabs favor accumulation of contaminants. Red crabs, sediment, and bottom water samples were taken from three distinct geographic locations representing areas with differing exposure to contaminant laden effluents from the Mississippi River. Inductively coupled plasma spectrophotometry and atomic absorption spectrophotometry were employed to determine levels of heavy metals in red crab muscle tissue. Ion site partitioning was used to determine metal speciation in sediments. Red crabs showed evidence of heavy metal bioaccumulation in all sample areas with high variability in contaminant levels in individual crabs for some metals. Bioavailability of metals in sediment did not always result in accumulation in muscle tissue. Copyright © 2015 Elsevier Ltd. All rights reserved.

Strongly-correlated crystal-field approach to heavy-fermion compounds and to 3d oxides

NASA Astrophysics Data System (ADS)

Radwanski, Ryszard; Ropka, Zofia

2005-03-01

The description of electronic and magnetic properties of real compounds like LaMnO3, LaCoO3, Na2V3O7, FeO, NdAl2 and ErNi5 as well as heavy-fermion superconductor UPd2Al3 and heavy-fermion metal YbRh2Si2, both zero-temperature ground state properties and thermodynamics, will be presented pointing out the existence of a discrete atomic-like low-energy, in the meV scale, electronic structure. This low-energy many-electron discrete atomic-like electronic structure is governed by very strong electron correlations, predominantly on-site, by the intra-atomic spin-orbit coupling and by details of the local surrounding (crystal-field interactions), but later is modified by inter-site interactions. Our studies indicate that there is the highest time to ``unquench'' the orbital moment in solid state physics in description of 3d-/4f-/5f-atom containing compounds and that heavy-fermion phenomena are of the relativistic origin.
Production of 14 MeV neutrons by heavy ions

DOEpatents

Brugger, Robert M.; Miller, Lowell G.; Young, Robert C.

1977-01-01

This invention relates to a neutron generator and a method for the production of 14 MeV neutrons. Heavy ions are accelerated to impinge upon a target mixture of deuterium and tritium to produce recoil atoms of deuterium and tritium. These recoil atoms have a sufficient energy such that they interact with other atoms of tritium or deuterium in the target mixture to produce approximately 14 MeV neutrons.
Non Covalent Interactions in Large Diamondoid Dimers in the Gas Phase - a Microwave Study

NASA Astrophysics Data System (ADS)

Perez, Cristobal; Sekutor, Marina; Fokin, Andrey A.; Blomeyer, Sebastian; Vishnevskiy, Yury V.; Mitzel, Norbert W.; Schreiner, Peter R.; Schnell, Melanie

2017-06-01

Accurate structure determination of large molecules still represents an ambitious challenge. Interesting benchmark systems for structure determination are large diamondoid dimers, whose structures are governed by strong intramolecular interactions. Recently, diamondoid dimers with unusually long central C-C bonds (up to 1.71 Å) were synthesized. This long central C-C bond was rationalized by numerous CH...HC-type dispersion attractions between the two halves of the molecule. The thermodynamic stabilization of molecules equipped with bulky groups has provided a conceptually new rationale, since until then it had been assumed that such molecules are highly unstable. We performed a broadband CP-FTMW spectroscopy study in the 2-8 GHz frequency range on oxygen-substituted diamondoid dimers (C_{26}H_{34}O_2, 28 heavy atoms) as well as diadamantyl ether to provide further insight into their structures. The experimental data are compared with results from quantum-chemical calculations and gas-phase electron diffraction. For the ether, we even obtained ^{13}C and ^{18}O isotopologues to generate the full heavy-atom substitution structure.
Application of solid phase extraction on multiwalled carbon nanotubes of some heavy metal ions to analysis of skin whitening cosmetics using ICP-AES.

PubMed

Alqadami, Ayoub A; Abdalla, Mohammad Abulhassan; AlOthman, Zeid A; Omer, Kamal

2013-01-14

A novel and highly sensitive method for the determination of some heavy metals in skin whitening cosmetics creams using multiwalled carbon nanotubes MWCNTs as solid phase extraction sorbent for the preconcentration of these heavy metals prior to their determination by inductively coupled plasma atomic emission spectrometry is described. Different practical parameters have been thoroughly investigated and the optimum experimental conditions were employed. The developed method was then applied for the determination of arsenic, bismuth, cadmium, mercury, lead and titanium in samples of skin whitening cosmetics. The detection limits under these conditions for As, Bi, Cd, Pb, Hg and Ti were 2.4, 4.08, 0.3, 2.1, 1.8, and 1.8 ng·mL-1, respectively. The relative standard deviations (RSDs) were found to be less than 2.0%. For validation, a certified reference material of NIST SRM 1570a spinach leaves was analyzed and the determined values were in good agreement with the certified values. The recoveries for spiked samples were found to be in the range of 89.6-104.4%.
O-Alkylated heavy atom carbohydrate probes for protein X-ray crystallography: Studies towards the synthesis of methyl 2-O-methyl-L-selenofucopyranoside.

PubMed

Sommer, Roman; Hauck, Dirk; Varrot, Annabelle; Imberty, Anne; Künzler, Markus; Titz, Alexander

2016-01-01

Selenoglycosides are used as reactive glycosyl donors in the syntheses of oligosaccharides. In addition, such heavy atom analogs of natural glycosides are useful tools for structure determination of their lectin receptors using X-ray crystallography. Some lectins, e.g., members of the tectonin family, only bind to carbohydrate epitopes with O-alkylated ring hydroxy groups. In this context, we report the first synthesis of an O -methylated selenoglycoside, specifically methyl 2- O -methyl-L-selenofucopyranoside, a ligand of the lectin tectonin-2 from the mushroom Laccaria bicolor . The synthetic route required a strategic revision and further optimization due to the intrinsic lability of alkyl selenoglycosides, in particular for the labile fucose. Here, we describe a successful synthetic access to methyl 2- O -methyl-L-selenofucopyranoside in 9 linear steps and 26% overall yield starting from allyl L-fucopyranoside.
Arsenic species analysis in porewaters and sediments using hydride generation atomic fluorescence spectrometry.

PubMed

Liao, Meng-xia; Deng, Tian-long

2006-01-01

It was observed that the atomic fluorescence emission due to As(V) could has a 10% to 40% of fluorescence emission signal during the determination of As(III) in the mixture of As(III) and As(V). Besides, interferes from heavy metals such as Pb(lIl), Cu(ll) can cause severe increase of the signals as compared to the insignificant effects caused by Cd(II), Zn(ll), Mn(II) and Fe(Ill). On the basis of further studies, the masking agent of 8-hydroxyquinoline was used as an efficient agent to eliminate interference of As(V) emission and the heavy metal of Cu2+ and Pb2+ in the measurements of arsenic species. After a series standard additions and CRM researches, a sensitive and interference-free analytical procedure was developed for the speciation of arsenic in samples of porewaters and sediments in Poyang Lake, China.
Quantum delayed-choice experiment with a single neutral atom.

PubMed

Li, Gang; Zhang, Pengfei; Zhang, Tiancai

2017-10-01

We present a proposal to implement a quantum delayed-choice (QDC) experiment with a single neutral atom, such as a rubidium or cesium atom. In our proposal, a Ramsey interferometer is adopted to observe the wave-like or particle-like behaviors of a single atom depending on the existence or absence of the second π/2-rotation. A quantum-controlled π/2-rotation on target atom is realized through a Rydberg-Rydberg interaction by another ancilla atom. It shows that a heavy neutral atom can also have a morphing behavior between the particle and the wave. The realization of the QDC experiment with such heavy neutral atoms not only is significant to understand the Bohr's complementarity principle in matter-wave and matter-particle domains but also has great potential on the quantum information process with neutral atoms.
Photoelectron spectroscopy of heavy atoms and molecules

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

White, M.G.

1979-07-01

The importance of relativistic interactions in the photoionization of heavy atoms and molecules has been investigated by the technique of photoelectron spectroscopy. In particular, experiments are reported which illustrate the effects of the spin-orbit interaction in the neutral ground state, final ionic states and continuum states of the photoionization target.
1D chain formation by coadsorption of Pb and Bi on Cu(001): Determination using low energy electron diffraction

NASA Astrophysics Data System (ADS)

Kabiruzzaman, Md; Ahmed, Rezwan; Nakagawa, Takeshi; Mizuno, Seigi

2017-10-01

Coadsorption of two heavy metals, Pb and Bi, on Cu(001) at room temperature has been studied using low energy electron diffraction (LEED). c(4 × 4), c(2 × 2), and c(9√{ 2}×√{ 2}) phases are obtained at different coverages; here, we have determined the best-fit structure of c(4 × 4) phase. This structure can be described as a 1D substitutional chain arrangement of Pb and Bi atoms between the Cu rows along the [110] direction. The unit cell in the two-dimensional (2D) surface consists of one Bi atom, two Pb atoms, and four Cu atoms with one vacancy at the center. The optimal structure parameters demonstrate that Bi atoms are located at fourfold-hollow sites and that Pb atoms are laterally displaced by 0.78 Å from the fourfold-hollow site toward the vacancy. The reasons for the formation of the c(4 × 4) structure upon deposition of Pb and Bi on Cu(001) are discussed in comparison with a similar structure formed by the individual adsorption of Pb on the same substrate.
Heavy Atom Effect of Bromine Significantly Enhances Exciton Utilization of Delayed Fluorescence Luminogens.

PubMed

Gan, Shifeng; Hu, Shimin; Li, Xiang-Long; Zeng, Jiajie; Zhang, Dongdong; Huang, Tianyu; Luo, Wenwen; Zhao, Zujin; Duan, Lian; Su, Shi-Jian; Tang, Ben Zhong

2018-05-23

Raising triplet exciton utilization of pure organic luminescent materials is of significant importance for efficiency advancement of organic light-emitting diodes (OLEDs). Herein, by introducing bromine atom(s) onto a typical molecule (bis(carbazol-9-yl)-4,5-dicyanobenzene) with thermally activated delayed fluorescence, we demonstrate that the heavy atom effect of bromine can increase spin-orbit coupling and promote the reverse intersystem crossing, which endow the molecules with more distinct delayed fluorescence. In consequence, the triplet exciton utilization is improved greatly with the increase of bromine atoms, affording apparently advanced external quantum efficiencies of OLEDs. Utilizing the enhancement effect of bromine atoms on delayed fluorescence should be a simple and promising design concept for efficient organic luminogens with high exciton utilization.
Use of Relativistic Effective Core Potentials in the Calculation of Electron-Impact Ionization Cross Sections

NASA Technical Reports Server (NTRS)

Huo, Winifred M.; Kim, Yong-Ki

1999-01-01

Based on the Binary-Encounter-Bethe (BEB) model, the advantage of using relativistic effective core potentials (RECP) in the calculation of total ionization cross sections of heavy atoms or molecules containing heavy atoms is discussed. Numerical examples for Ar, Kr, Xe, and WF6 are presented.
Heavy metals effects on forage crops yields and estimation of elements accumulation in plants as affected by soil.

PubMed

Grytsyuk, N; Arapis, G; Perepelyatnikova, L; Ivanova, T; Vynograds'ka, V

2006-02-01

Heavy metals (Cu, Cd, Pb, Zn) effect on the productivity of forage crops (clover and perennial cereal grasses) and their accumulation in plants, depending on the concentration of these elements in a soil, has been studied in micro-field experiments on three types of soil. The principle objective was to determine regularities of heavy metals migration in a soil-plant system aiming the estimation of permissible levels of heavy metals content in soils with the following elaboration of methods, which regulate the toxicants transfer to plants. Methods of field experiments, agrochemical and atomic absorption analysis were used. Results were statistically treated by Statistica 6.0, S-Plus 6. Experimental results have shown that the intensity of heavy metals accumulation in plants depends on the type of the soil, the species of plants, the physicochemical properties of heavy metals and their content in the soil. Logarithmic interdependency of heavy metals concentration in soils and their accumulation in plants is suggested. However, the strong correlation between the different heavy metals concentrations in the various soils and the yield of crops was not observed. Toxicants accumulation in crops decreased in time.
Relativistic (SR-ZORA) quantum theory of atoms in molecules properties.

PubMed

Anderson, James S M; Rodríguez, Juan I; Ayers, Paul W; Götz, Andreas W

2017-01-15

The Quantum Theory of Atoms in Molecules (QTAIM) is used to elucidate the effects of relativity on chemical systems. To do this, molecules are studied using density-functional theory at both the nonrelativistic level and using the scalar relativistic zeroth-order regular approximation. Relativistic effects on the QTAIM properties and topology of the electron density can be significant for chemical systems with heavy atoms. It is important, therefore, to use the appropriate relativistic treatment of QTAIM (Anderson and Ayers, J. Phys. Chem. 2009, 115, 13001) when treating systems with heavy atoms. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.
The project of the mass separator of atomic nuclei produced in heavy ion induced reactions

NASA Astrophysics Data System (ADS)

Oganessian, Yu. Ts.; Shchepunov, V. A.; Dmitriev, S. N.; Itkis, M. G.; Gulbekyan, G. G.; Khabarov, M. V.; Bekhterev, V. V.; Bogomolov, S. L.; Efremov, A. A.; Pashenko, S. V.; Stepantsov, S. V.; Yeremin, A. V.; Yavor, M. I.; Kalimov, A. G.

2003-05-01

A new separator and mass analyzer, named MASHA (mass analyzer of super heavy atoms), has been designed at the Flerov Laboratory JINR Dubna to separate and measure masses of nuclei and molecules with precision better than 10 -3. The set up can work in the wide mass range from A≈20 to A≈500, its mass acceptance is as large as ±2.8%. In particular, it allows unambiguous mass identification of super heavy nuclei with a resolution better than 1 amu at the level of 300 amu. Synthesized in nuclear reactions nuclides are emitted from an ECR ion source at energy E=40 kV and charge state Q=+1. Then they pass the following steps of separation and analysis: the first section of rough separation, the second section of separation and mass analysis and the final section of separation with a 90° electrostatic deflector. In the focal plane of the device, a focal plane detector determines positions (masses) of studied nuclei. Ion optics of the analyzer, optimized up to the second order, is considered. Description of its elements and subsystems is given.
Heavy atom labeled nucleotides for measurement of kinetic isotope effects.

PubMed

Weissman, Benjamin P; Li, Nan-Sheng; York, Darrin; Harris, Michael; Piccirilli, Joseph A

2015-11-01

Experimental analysis of kinetic isotope effects represents an extremely powerful approach for gaining information about the transition state structure of complex reactions not available through other methodologies. The implementation of this approach to the study of nucleic acid chemistry requires the synthesis of nucleobases and nucleotides enriched for heavy isotopes at specific positions. In this review, we highlight current approaches to the synthesis of nucleic acids enriched site specifically for heavy oxygen and nitrogen and their application in heavy atom isotope effect studies. This article is part of a special issue titled: Enzyme Transition States from Theory and Experiment. Copyright © 2015 Elsevier B.V. All rights reserved.
Atomic Data for Nebular Abundance Determinations: Photoionization and Recombination Properties of Xenon Ions

NASA Astrophysics Data System (ADS)

Sterling, Nicholas C.; Kerlin, Austin B.

2016-01-01

We present preliminary results of a study of the photoionization (PI) and recombination properties of low-charge Xe ions. The abundances of neutron(n)-capture elements (atomic number Z > 30) are of interest in planetary nebulae (PNe) since they can be enriched by slow n-capture nucleosynthesis (the ``s-process'') in the progenitor asymptotic giant branch (AGB) stars. Xe is particularly valuable, because it is the most widely-observed ``heavy-s'' species (Z > 40) in PNe. Its abundance relative to lighter n-capture elements can be used to determine s-process neutron exposures, and constrain s-process enrichment patterns as a function of progenitor metallicity. Using the atomic structure code AUTOSTRUCTURE (Badnell 2011, Comp. Phys. Comm., 182, 1528), we have computed multi-configuration Breit-Pauli distorted-wave PI cross sections and radiative recombination (RR) and dielectronic recombination (DR) rate coefficients for neutral through six-times ionized Xe, data which are critically needed for accurate Xe abundance determinations in ionized nebulae. We find good agreement between our computed direct PI cross sections and experimental measurements. Internal uncertainties are estimated for our calculations by using three different configuration interaction expansions for each ion, and by testing the sensitivity of our results to the radial orbital scaling parameters. As found for other n-capture elements (Sterling & Witthoeft 2011, A&A, 529, A147; Sterling 2011, A&A, 533, A62), DR is the dominant recombination mechanism for Xe ions at nebular temperatures (~104 K). Following Sterling et al. (2015, ApJS, 218, 25), these data will be added to nebular modeling codes to compute ionization correction factors for unobserved Xe ions in PNe, which will enable elemental Xe abundances to be determined with much higher accuracy than is currently possible. This work is supported by NSF award AST-1412928.
Fundamental Studies on Donor-acceptor Conjugated Polymers Containing 'Heavy' Group 14 and Group 16 Elements

NASA Astrophysics Data System (ADS)

Gibson, Gregory Laird

One advantage of conjugated polymers as organic materials is that their properties may be readily tuned through covalent modifications. This thesis presents studies on the structure-property relationships resulting from single- and double-atom substitutions on an alternating donor-acceptor conjugated polymer. Specifically, single selenium and tellurium atoms have been incorporated into the acceptor monomer in place of sulfur; silicon and germanium atoms have been substituted in place of carbon at the donor monomer bridge position. The carbon-donor/ tellurium-acceptor polymer was synthesized by a post-polymerization reaction sequence and demonstrated the utility of heavy group 16 atoms to red shift a polymer absorption spectrum. Density functional theory calculations point to a new explanation for this result invoking the lower heavy atom ionization energy and reduced aromaticity of acceptor monomers containing selenium and tellurium compared to sulfur. Absorption and emission experiments demonstrate that both silicon and germanium substitutions in the donor slightly blue shift the polymer absorption spectrum. Polymers containing sulfur in the acceptor are the strongest light absorbers of all polymers studied here. Molecular weight and phenyl end capping studies show that molecular weight appears to affect polymer absorption to the greatest degree in a medium molecular weight regime and that these effects have a significant aggregation component. Solar cell devices containing either the silicon- or germanium-donor/selenium-acceptor polymer display improved red light harvesting or hole mobility relative to their structural analogues. Overall, these results clarify the effects of single atom substitution on donor-acceptor polymers and aid in the future design of polymers containing heavy atoms.
Observation of the continuous stern-gerlach effect on an electron bound in an atomic Ion

PubMed

Hermanspahn; Haffner; Kluge; Quint; Stahl; Verdu; Werth

2000-01-17

We report on the first observation of the continuous Stern-Gerlach effect on an electron bound in an atomic ion. The measurement was performed on a single hydrogenlike ion ( 12C5+) in a Penning trap. The measured g factor of the bound electron, g = 2.001 042(2), is in excellent agreement with the theoretical value, confirming the relativistic correction at a level of 0.1%. This proves the possibility of g-factor determinations on atomic ions to high precision by using the continuous Stern-Gerlach effect. The result demonstrates the feasibility of conducting experiments on single heavy highly charged ions to test quantum electrodynamics in the strong electric field of the nucleus.
Determination of trace heavy metals in soil and sediments by atomic spectrometry following preconcentration with Schiff bases on Amberlite XAD-4.

PubMed

Kara, Derya; Fisher, Andrew; Hill, Steve J

2009-06-15

A matrix separation and analyte preconcentration system using Amberlite XAD copolymer resins functionalized by Schiff base reactions coupled with atomic spectrometry has been developed. Three different functionalized Amberlite XAD resins were synthesized using 4-phenylthiosemicarbazide, 2,3-dihydroxybenzaldehyde and 2-thiophenecarboxaldehyde as reagents. These resins could be used to preconcentrate transition and other trace heavy metal analytes from nitric acid digests of soil and sediment samples. Analyte retention was shown to work well at pH 6.0. After treatment of the digests with sodium fluoride and buffering to pH 6, samples that contain extremely large concentrations of iron were analysed for trace analytes without the excess iron overloading the capacity of the resin. The analytes Cd, Co, Cu, Ni and Pb were preconcentrated from acid extracts of certified soil/sediment samples and then eluted with 0.1M HNO(3) directly to the detection system. Flame atomic absorption spectrometry was used as a means of detection during the studies. The efficiency of the chelating resin and the accuracy of the proposed method were evaluated by the analysis of soil (SO-2) and sediment (LGC 6157 and MESS-3) certified reference materials.
Electron Impact Ionization Cross Sections in Rb and Cs.

NASA Astrophysics Data System (ADS)

Reddish, T. J.; Lukomski, M.; Sutton, S.; Kedzierski, W.; McConkey, J. W.; Bartschat, K.; Bartlett, P. L.; Stelbovics, A. T.; Bray, I.

2006-05-01

We present a new atom trapping technique for determining absolute, total ionisation cross sections (TICS) out of an excited atom. The novel feature of this method is in utilizing Doppler cooling of neutral atoms to determine ionisation cross sections. This fluorescence-monitoring experiment, which is a variant of the `trap loss' technique, has enabled us to obtain the experimental electron impact ionisation cross sections out of the Cs 6^2P3/2 excited state between 7 - 400 eV. New CCC, R-Matrix with Pseudo-States (RMPS), and Born approximation single ionisation cross sections (SICS) are also presented for both the ground and excited states of Cs and Rb, and compared with the available experimental data. The comparison of the results reveals the importance of the autoionisation and multiple ionisation contributions to the TICS. The autoionisation contribution appears to be substantial for ionisation out of the Cs 6^2P and Rb 5^2P excited states; ˜ 3-4 larger than the direct ionisation contribution predicted by CCC at ˜ 30-50 eV. This surprising result shows the importance of multi-electron processes in determining the ionisation cross sections of heavy alkali atoms.

Application of Solid Phase Extraction on Multiwalled Carbon Nanotubes of Some Heavy Metal Ions to Analysis of Skin Whitening Cosmetics Using ICP-AES

PubMed Central

ALqadami, Ayoub A.; Abdalla, Mohammad Abulhassan; ALOthman, Zeid A.; Omer, Kamal

2013-01-01

A novel and highly sensitive method for the determination of some heavy metals in skin whitening cosmetics creams using multiwalled carbon nanotubes MWCNTs as solid phase extraction sorbent for the preconcentration of these heavy metals prior to their determination by inductively coupled plasma atomic emission spectrometry is described. Different practical parameters have been thoroughly investigated and the optimum experimental conditions were employed. The developed method was then applied for the determination of arsenic, bismuth, cadmium, mercury, lead and titanium in samples of skin whitening cosmetics. The detection limits under these conditions for As, Bi, Cd, Pb, Hg and Ti were 2.4, 4.08, 0.3, 2.1, 1.8, and 1.8 ng·mL−1, respectively. The relative standard deviations (RSDs) were found to be less than 2.0%. For validation, a certified reference material of NIST SRM 1570a spinach leaves was analyzed and the determined values were in good agreement with the certified values. The recoveries for spiked samples were found to be in the range of 89.6–104.4%. PMID:23343988
Bioaccumulation of heavy metals in crop plants grown near Almeda Textile Factory, Adwa, Ethiopia.

PubMed

Gitet, Hintsa; Hilawie, Masho; Muuz, Mehari; Weldegebriel, Yirgaalem; Gebremichael, Dawit; Gebremedhin, Desta

2016-09-01

The contents of heavy metals cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn) present in water (wastewater and wetland), soils, and food crops collected from the vicinity of Almeda Textile Factory were quantified using Flame Atomic Absorption Spectrometer (FAAS) in order to assess the environmental impact of the textile factory. The contents of heavy metals determined in the wastewater were found below the recommended limit set by WHO and United States Environmental Protection Agency (US EPA) except for Cr, which was found slightly higher than WHO permissible limit. Besides, the contents of the heavy metals determined in soils were below the permissible level of FAO/WHO and Canada maximum allowable limits. Moreover, only the concentrations of Cd and Pb were found above the permissible level set by FAO/WHO in the crop plants studied. Generally, the mean concentrations of heavy metals in the plants were in the decreasing order of: Mn > Zn > Cu > Pb > Ni > Co > Cr > Cd. Nevertheless, higher bioconcentration factor (BCF) was found for Cd (0.108-1.156) followed by Zn (0.081-0.499). In conclusion, comparison of heavy metal concentrations with the permissible limits in all collected sample types i.e. water, soil, and crop plants did not show significant pollution from the factory.
Optical Thin Film Thickness Measurement for the Single Atom Microscope

NASA Astrophysics Data System (ADS)

Nelson, Courtney; Frisbie, Dustin; Singh, Jaideep; Spinlab Team

2017-09-01

The Single Atom Microscope Project proposes an efficient, selective, and sensitive method to measure the 1022Ne+24 He ->1225 Mg + n reaction. This rare nuclear reaction is a source of neutrons for heavy element development through the slow neutron capture process. This method embeds Magnesium atoms in a solid neon film. The Magnesium atoms exhibit a shifted fluorescence spectrum allowing for the detection of individual fluorescence photons against the excitation light background. Currently, Ytterbium is used in place of Magnesium-25 because it has been more thoroughly studied than Magnesium and we expect it to have a brighter signal. To identify the signal emitted from the Ytterbium atoms, we need to quantify the amount of signal and background per atom in the neon film. We need to know the film thickness to find the number of atoms in the film to determine the amount of light emitted per atom. In preparation for the neon film measurement, I constructed an experiment to advance the understanding of what is required to optically measure a thin film by using a cover glass slide in place of the thin film. This preliminary experiment has determined a measurement method for finding the thickness of a neon thin film on a sapphire substrate. This work is supported by Michigan State University, U.S. National Science Foundation under Grant Number 1654610, and U.S. NSF REU.
Biophysical modeling of fragment length distributions of DNA plasmids after X and heavy-ion irradiation analyzed by atomic force microscopy.

PubMed

Elsässer, Thilo; Brons, Stephan; Psonka, Katarzyna; Scholz, Michael; Gudowska-Nowak, Ewa; Taucher-Scholz, Gisela

2008-06-01

The investigation of fragment length distributions of plasmid DNA gives insight into the influence of localized energy distribution on the induction of DNA damage, particularly the clustering of double-strand breaks. We present an approach that determines the fragment length distributions of plasmid DNA after heavy-ion irradiation by using the Local Effect Model. We find a good agreement of our simulations with experimental fragment distributions derived from atomic force microscopy (AFM) studies by including experimental constraints typical for AFM. Our calculations reveal that by comparing the fragmentation in terms of fluence, we can uniquely distinguish the effect of different radiation qualities. For very high-LET irradiation using nickel or uranium ions, no difference between their fragment distributions can be expected for the same dose level. However, for carbon ions with an intermediate LET, the fragmentation pattern differs from the distribution for very high-LET particles. The results of the model calculations can be used to determine the optimal experimental parameters for a demonstration of the influence of track structure on primary radiation damage. Additionally, we compare the results of our model for two different plasmid geometries.
Effects of metal-contaminated soils on the accumulation of heavy metals in gotu kola (Centella asiatica) and the potential health risks: a study in Peninsular Malaysia.

PubMed

Ong, Ghim Hock; Wong, Ling Shing; Tan, Ai Li; Yap, Chee Kong

2016-01-01

Centella asiatica is a commonly used medicinal plant in Malaysia. As heavy metal accumulation in medicinal plants which are highly consumed by human is a serious issue, thus the assessment of heavy metals in C. asiatica is important for the safety of consumers. In this study, the heavy metal accumulation in C. asiatica and the potential health risks were investigated. Samples of C. asiatica and surface soils were collected from nine different sites around Peninsular Malaysia. The concentration of six heavy metals namely Cd, Cu, Ni, Fe, Pb and Zn were determined by air-acetylene flame atomic absorption spectrophotometer (AAS). The degree of anthropogenic influence was assessed by calculating the enrichment factor (EF) and index of geoaccumulation (Igeo). The heavy metal uptake into the plant was estimated through the calculation of translocation factor (TF), bioconcentration factor (BCF) and correlation study. Estimated daily intakes (EDI) and target hazard quotients (THQ) were used to determine the potential health risk of consuming C. asiatica. The results showed that the overall surface soil was polluted by Cd, Cu and Pb, while the uptake of Zn and Ni by the plants was high. The value of EDI and THQ showed that the potential of Pb toxicity in C. asiatica was high as well. As heavy metal accumulation was confirmed in C. asiatica, daily consumption of the plant derived from polluted sites in Malaysia was not recommended.
Statistical radii associated with amino acids to determine the contact map: fixing the structure of a type I cohesin domain in the Clostridium thermocellum cellulosome

NASA Astrophysics Data System (ADS)

Chwastyk, Mateusz; Poma Bernaola, Adolfo; Cieplak, Marek

2015-07-01

We propose to improve and simplify protein refinement procedures through consideration of which pairs of amino acid residues should form native contacts. We first consider 11 330 proteins from the CATH database to determine statistical distributions of contacts associated with a given type of amino acid. The distributions are set across the distances between the α-C atoms that are in contact. Based on this data, we determine typical radii of effective spheres that can be placed on the α-C atoms in order to reconstruct the distribution of the contact lengths. This is done by checking for overlaps with enlarged van der Waals spheres associated with heavy atoms on other amino acids. The resulting contacts can be used to identify non-native contacts that may arise during the time evolution of structure-based models. Here, the radii are used to guide reconstruction of nine missing side chains in a type I cohesin domain with the Protein Data Bank code 1AOH. We first identify the likely missing contacts and then sculpt the corresponding side chains by standard refinement tools to achieve consistency with the expected contact map. One ambiguity in refinement is resolved by determining all-atom conformational energies.
Physics Division progress report for period ending September 30, 1983

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

Not Available

1983-12-01

Research and development activities are summarized in the following areas: Holifield Heavy Ion Research Facility, nuclear physics, the UNISOR program, accelerator-based atomic physics, theoretical physics, nuclear science applications, atomic physics and plasma diagnostics for fusion program, high-energy physics, the nuclear data project, and the relativistic heavy-ion collider study. Publications and papers presented are listed. (WHK)
First-principles study of the heavy metal atoms X (X=Au, Hg, Tl or Pb) doped monolayer WS2

NASA Astrophysics Data System (ADS)

Xie, Ling-Yun; Zhang, Jian-Min

2017-12-01

The heavy metal atoms X (X = Au, Hg, Tl or Pb) doped monolayer WS2 systems have been studied by using the spin-polarized first-principles calculations. Although pure monolayer WS2 system is a nonmagnetic semiconductor with a direct band gap of 1.820 eV, the Au and Hg atoms doped monolayer WS2 systems change to half-metal (HM) ferromagnets with the total magnetic moments 0.697 and 1.776 μB as well as the smaller spin-down gaps 0.605 and 0.527 eV, respectively, while the Tl and Pb atoms doped monolayer WS2 systems change to magnetic metal with the total magnetic moment 0.584 μB and a nonmagnetic metal. From the minimization of the formation energy, we find that it is easy to incorporate these heavy metal atoms into monolayer WS2 system under S-rich condition, especially for the Au doped monolayer WS2 system not only easily to be formed but also a HM ferromagnet, and thus the best candidate used in the spintronic devices.
Modeling Emission of Heavy Energetic Neutral Atoms from the Heliosphere

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

Swaczyna, Paweł; Bzowski, Maciej, E-mail: pswaczyna@cbk.waw.pl

2017-09-10

Observations of energetic neutral atoms (ENAs) are a fruitful tool for remote diagnosis of the plasma in the heliosphere and its vicinity. So far, instruments detecting ENAs from the heliosphere were configured for observations of hydrogen atoms. Here, we estimate emissions of ENAs of the heavy chemical elements helium, oxygen, nitrogen, and neon. A large portion of the heliospheric ENAs is created in the inner heliosheath from neutralized interstellar pick-up ions (PUIs). We modeled this process and calculated full-sky intensities of ENAs for energies 0.2–130 keV/nuc. We found that the largest fluxes among considered species are expected for helium, smallermore » for oxygen and nitrogen, and smallest for neon. The obtained intensities are 50–10{sup 6} times smaller than the hydrogen ENA intensities observed by IBEX . The detection of heavy ENAs will be possible if a future ENA detector is equipped with the capability to measure the masses of observed atoms. Because of different reaction cross-sections among the different species, observations of heavy ENAs can allow for a better understanding of global structure of the heliosphere as well as the transport and energization of PUIs in the heliosphere.« less
Modeling Emission of Heavy Energetic Neutral Atoms from the Heliosphere

NASA Astrophysics Data System (ADS)

Swaczyna, Paweł; Bzowski, Maciej

2017-09-01

Observations of energetic neutral atoms (ENAs) are a fruitful tool for remote diagnosis of the plasma in the heliosphere and its vicinity. So far, instruments detecting ENAs from the heliosphere were configured for observations of hydrogen atoms. Here, we estimate emissions of ENAs of the heavy chemical elements helium, oxygen, nitrogen, and neon. A large portion of the heliospheric ENAs is created in the inner heliosheath from neutralized interstellar pick-up ions (PUIs). We modeled this process and calculated full-sky intensities of ENAs for energies 0.2-130 keV/nuc. We found that the largest fluxes among considered species are expected for helium, smaller for oxygen and nitrogen, and smallest for neon. The obtained intensities are 50-106 times smaller than the hydrogen ENA intensities observed by IBEX. The detection of heavy ENAs will be possible if a future ENA detector is equipped with the capability to measure the masses of observed atoms. Because of different reaction cross-sections among the different species, observations of heavy ENAs can allow for a better understanding of global structure of the heliosphere as well as the transport and energization of PUIs in the heliosphere.
Heavy Metal Uptake by Herbs. IV. Influence of Soil pH on the Content of Heavy Metals in Valeriana officinalis L.

PubMed

Adamczyk-Szabela, Dorota; Markiewicz, Justyna; Wolf, Wojciech M

The aim of the study was to estimate the influence of soil pH on the uptake of copper, zinc, and manganese by Valeriana officinalis . Preliminary studies involved soil analyses to determine acidity, organic matter content, and copper, zinc, and manganese total and bioavailable forms. The study involved atomic absorption spectrometry to determine the concentration of the elements, and mineral soil of pH = 5.1 was used in the study, as being typical for central Poland. The copper, zinc, and manganese contents were determined in plants grown in soils which had been modified to cover a wide range of pH values 3÷13. The intensity of germination was strongly pH dependent with the highest yield obtained in original, unmodified soil. Surprisingly, high soil alkalinity stimulated copper and manganese uptake while at the same time resulting in a decrease in zinc content.
Safety Evaluation of Osun River Water Containing Heavy Metals and Volatile Organic Compounds (VOCs) in Rats.

PubMed

Azeez, L; Salau, A K; Adewuyi, S O; Osineye, S O; Tijani, K O; Balogun, R O

2015-12-20

This study evaluated the pH, heavy metals and volatile organic compounds (VOCs) in Osun river water. It also evaluated its safety in rats. Heavy metals were determined by atomic absorption spectrophotometry (AAS) while VOCs were determined by gas chromatography coupled with flame ionization detector (GC-FID). Male and female rats were exposed to Osun river water for three weeks and then sacrificed. The abundance of heavy metals in Osun river followed the trend Pb > Cd > Zn > Fe > Cr > Cu while VOCs followed the trend benzene < ethylbenzene < toluene < xylene. The concentrations of Pb, Cd and benzene were higher than the permissible limits of Standards Organization of Nigeria (SON) and World Health Organization (WHO) respectively. Rats exposed to Osun river water for three weeks had increased WBC, thiobarbituric acid reactive substances (TBARS), serum proteins and serum aminotransferases. There were also significant decreases in HCT, PLT, liver aminotransferases and liver glutathione compared to the control. These results show that the pollutants in Osun river water are capable of inducing hematological imbalance and liver cell injury. The toxicity induced in blood was sex-dependent affecting female rats more than male rats.
The use of feather as an indicator for heavy metal contamination in house crow (Corvus splendens) in the Klang area, Selangor, Malaysia.

PubMed

Janaydeh, Mohammed; Ismail, Ahmad; Zulkifli, Syaizwan Zahmir; Bejo, Mohd Hair; Aziz, Nor Azwady Abd; Taneenah, Ayat

2016-11-01

The Klang area of Peninsular Malaysia has experienced rapid industrial growth with intense activities, which can increase the concentration of pollutants in the environment that significantly impact on habitats and the human health. The purpose of this study was to determine the levels of selected heavy metals (Cu, Zn, Ni, Fe, and Pb) in the heart, lung, brain, liver, kidney, muscle tissues, and feathers of house crow, Corvus splendens, in Klang, Peninsular Malaysia. House crow samples were collected from the Klang area through the Department of Public Health at Majlis Perbandaran Klang. Quantitative determination of heavy metals was carried out using atomic absorption spectrophotometer (AAS). The result shows the presence of heavy metals in all biological samples of house crows. For heavy metals in all the house crow tissues analyzed, Fe concentrations were the highest, followed by those of Zn, Cu, Pb, and Ni. The feathers and kidney accumulated high concentrations of Pb, whereas the liver accumulated high concentrations of essential heavy metals (Fe > Zn > Cu > Ni). Significant variations were also detected in the concentrations of Pb among adult and juvenile and male and female bird samples. The results also revealed significant positive correlations between Pb metal concentration in the breast feathers and all internal organs. Accumulation of toxic heavy metals in feathers reflected storing and elimination processes, while the accumulation of toxic heavy metals in the kidney can be consequential to chronic exposure. The present study clearly shows the usefulness of house crow breast feather as a suitable indicator for heavy metal accumulation in the internal organs of house crows in the Klang area.
Physics Division annual review, 1 April 1980-31 March 1981

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

Not Available

1982-06-01

Progress in nuclear physics research is reported in the following areas: medium-energy physics (pion reaction mechanisms, high-resolution studies and nuclear structure, and two-nucleon physics with pions and electrons); heavy-ion research at the tandem and superconducting linear accelerator (resonant structure in heavy-ion reactions, fusion cross sections, high angular momentum states in nuclei, and reaction mechanisms and distributions of reaction strengths); charged-particle research; neutron and photonuclear physics; theoretical physics (heavy-ion direct-reaction theory, nuclear shell theory and nuclear structure, nuclear matter and nuclear forces, intermediate-energy physics, microscopic calculations of high-energy collisions of heavy ions, and light ion direct reactions); the superconducting linac; acceleratormore » operations; and GeV electron linac. Progress in atomic and molecular physics research is reported in the following areas: dissociation and other interactions of energetic molecular ions in solid and gaseous targets, beam-foil research and collision dynamics of heavy ions, photoionization- photoelectron research, high-resolution laser rf spectroscopy with atomic and molecular beams, moessbauer effect research, and theoretical atomic physics. Studies on interactions of energetic particles with solids are also described. Publications are listed. (WHK)« less
Measurement of the first ionization potential of lawrencium, element 103.

PubMed

Sato, T K; Asai, M; Borschevsky, A; Stora, T; Sato, N; Kaneya, Y; Tsukada, K; Düllmann, Ch E; Eberhardt, K; Eliav, E; Ichikawa, S; Kaldor, U; Kratz, J V; Miyashita, S; Nagame, Y; Ooe, K; Osa, A; Renisch, D; Runke, J; Schädel, M; Thörle-Pospiech, P; Toyoshima, A; Trautmann, N

2015-04-09

The chemical properties of an element are primarily governed by the configuration of electrons in the valence shell. Relativistic effects influence the electronic structure of heavy elements in the sixth row of the periodic table, and these effects increase dramatically in the seventh row--including the actinides--even affecting ground-state configurations. Atomic s and p1/2 orbitals are stabilized by relativistic effects, whereas p3/2, d and f orbitals are destabilized, so that ground-state configurations of heavy elements may differ from those of lighter elements in the same group. The first ionization potential (IP1) is a measure of the energy required to remove one valence electron from a neutral atom, and is an atomic property that reflects the outermost electronic configuration. Precise and accurate experimental determination of IP1 gives information on the binding energy of valence electrons, and also, therefore, on the degree of relativistic stabilization. However, such measurements are hampered by the difficulty in obtaining the heaviest elements on scales of more than one atom at a time. Here we report that the experimentally obtained IP1 of the heaviest actinide, lawrencium (Lr, atomic number 103), is 4.96(+0.08)(-0.07) electronvolts. The IP1 of Lr was measured with (256)Lr (half-life 27 seconds) using an efficient surface ion-source and a radioisotope detection system coupled to a mass separator. The measured IP1 is in excellent agreement with the value of 4.963(15) electronvolts predicted here by state-of-the-art relativistic calculations. The present work provides a reliable benchmark for theoretical calculations and also opens the way for IP1 measurements of superheavy elements (that is, transactinides) on an atom-at-a-time scale.
[Distribution characteristics of heavy metals along an elevation gradient of montane forest].

PubMed

Wan, Jia-rong; Nie, Ming; Zou, Qin; Hu, Shao-chang; Chen, Jia-kuan

2011-12-01

In the present paper, the concentrations of fourteen heavy metals (Fe, Al, Ti, Cu, Cr, Mn, V, Zn, Ni, Co, Pb, Se, Cd and As) were determined by ICP-AES and atomic absorption spectroscopy along an elevation gradient of montane forest. The results show that the elevation gradient had significant effects on the concentrations of Fe, Al, Ti, V, Pb and As. And the concentrations of Cu, Cr, Mn, Zn, Ni, Co, Se and Cd were not significantly affected by the elevation gradient. Because the studying area is red soil, the elevation gradient had significant effects on the concentrations of Fe, Al and Ti which are characteristic heavy metals of red soil, suggesting that the red soil at different elevations has different intensities of weathering desilication and bioaccumulation. Other heavy metals have different relationships with the elevation gradient, such as the concentrations of Cr, Zn and Cd were high at relatively high elevation and Pb and As were high at relatively low elevation. These results suggest that the different elevations of montane forest soils were polluted by differently types of heavy metals.
Global and local approaches to population analysis: Bonding patterns in superheavy element compounds

NASA Astrophysics Data System (ADS)

Oleynichenko, Alexander; Zaitsevskii, Andréi; Romanov, Stepan; Skripnikov, Leonid V.; Titov, Anatoly V.

2018-03-01

Relativistic effective atomic configurations of superheavy elements Cn, Nh and Fl and their lighter homologues (Hg, Tl and Pb) in their simple compounds with fluorine and oxygen are determined using the analysis of local properties of molecular Kohn-Sham density matrices in the vicinity of heavy nuclei. The difference in populations of atomic spinors with the same orbital angular momentum and different total angular momenta is demonstrated to be essential for understanding the peculiarities of chemical bonding in superheavy element compounds. The results are fully compatible with those obtained by the relativistic iterative version of conventional projection analysis of global density matrices.
An experimental investigation of fractionation by sputter deposition. [application to solar wind irradiation of lunar soil

NASA Technical Reports Server (NTRS)

Paruso, D. M.; Cassidy, W. A.; Hapke, B. W.

1978-01-01

Artificial glass targets composed of elements varying widely in atomic weight were irradiated at an angle of incidence of 45 deg by 2-keV hydrogen ions at a current density of .33 mA/sq cm, and sputtered atoms were caught on a molybdenum film. Analyses of the sputter-deposited films and unsputtered target glasses were carried out by electron microprobe. The backward-sputtered component was found to be enriched in elements of low atomic weight, while the forward-sputtered component was enriched in heavy atoms. These results indicate that at the lunar surface lighter elements and isotopes would tend to be ejected in backward directions, escaping directly through the openings which admit bombarding ions without first striking an adjacent grain surface; heavy elements and isotopes would be forward-sputtered deeper into the soil and be preferentially retained, contributing to the reported enrichments of heavy elements and isotopes. Additional results show that the binding energy of an element in its oxide form influences the sticking coefficient of a sputtered atom; elements of low binding energy are likely to desorb, while elements of high binding energy tend to stick to the first bounce surface.
Determination of Heavy Metals Concentration in Traditional Herbs Commonly Consumed in the United Arab Emirates

PubMed Central

Dghaim, Rania; Al Khatib, Safa; Rasool, Husna; Ali Khan, Munawwar

2015-01-01

Herbs are extensively consumed in the United Arab Emirates for their flavoring and medicinal properties. This study aimed at determining the concentration of heavy metals in selected traditional herbs consumed in the United Arab Emirates (UAE). A total of 81 samples of seven herbs, parsley (Petroselinum crispum), basil (Ocimum basilicum), sage (Salvia officinalis), oregano (Origanum vulgare), mint (Mentha spicata), thyme (Thymus vulgaris), and chamomile (Matricaria chamomilla), were purchased from the local market in Dubai and analyzed for their cadmium, lead, copper, iron, and zinc contents. Microwave-assisted digestion was applied for the dissolution of the samples and heavy metals concentration was determined using Atomic Absorption Spectrometry (AAS). Metals were found to be present in varied concentrations in the herb samples. The concentration ranges were found as follows: less than 0.1–1.11 mg·kg−1 for cadmium, less than 1.0–23.52 mg·kg−1 for lead, 1.44–156.24 mg·kg−1 for copper, 12.65–146.67 mg·kg−1 for zinc, and 81.25–1101.22 mg·kg−1 for iron. The findings of the study suggest that most of the analyzed herbs contained unsafe levels of heavy metals that exceeded the World Health Organization (WHO) permissible limits (PL). PMID:26000023
Geoaccumulation assessment of heavy metal pollution in Ikwo soils, eastern Nigeria.

PubMed

Tyopine, Andrew A; Jayeoye, Titilope J; Okoye, Chukwuma O B

2018-01-04

An imbalance in the environment's composition leads to significant effect on human activities such as farming. Of importance are heavy metals which are introduced anthropogenically or naturally. This calls for environmental monitoring and subsequent remediation if needed. An environmental monitoring exercise was conducted on Ikwo soils of Ebonyi State, eastern Nigeria with the aim of determining concentration levels for possible remediation. A total of 18 soil composite samples taken at 0-50 cm below soil surface from fallowed and cultivated soils not fertilized were subjected to heavy metal analyses and fertility indices like: organic matter (OM), cation exchange capacity (CEC), % total nitrogen (%TN), organic carbon (OC), and salinity. A correlation at 95% confidence level between geo-accumulations (I geo ) of the various heavy metals with salinity, OM, and CEC of the sampled soils reveals that I geo could be a contributing factor to the fertility status of the soils. With the aid of inductively coupled plasma atomic emission spectrophotometer (ICP-AES), the distribution pattern was determined as Mn> Fe> Zn>Cu> Mo> Cd> V>Hg>Ti> Ni>Bi> Pb> Co>Ag>Au> Cr>Pd>Pt. The I geo of the heavy metals in the study area varied from heavily to extremely contaminated levels. A remediation exercise was recommended on Ikwo soils due to their high salinity level and low CEC.

Removal of heavy metals from tannery effluents of Ambur industrial area, Tamilnadu by Arthrospira (Spirulina) platensis.

PubMed

Balaji, S; Kalaivani, T; Rajasekaran, C; Shalini, M; Vinodhini, S; Priyadharshini, S Sunitha; Vidya, A G

2015-06-01

The present study was carried out with the tannery effluent contaminated with heavy metals collected from Ambur industrial area to determine the phycoremediation potential of Arthrospira (Spirulina) platensis. Two different concentrations (50 and 100 %) of heavy metals containing tannery effluent treated with A. platensis were analysed for growth, absorption spectra, biochemical properties and antioxidant enzyme activity levels. The effluent treatments revealed dose-dependent decrease in the levels of A. platensis growth (65.37 % for 50 % effluent and 49.32 % for 100 % effluent), chlorophyll content (97.43 % for 50 % effluent and 71.05 % for 100 % effluent) and total protein content (82.63 % for 50 % effluent and 62.10 % for 100 % effluent) that leads to the reduction of total solids, total dissolved solids and total suspended solids. A. platensis with lower effluent concentration was effective than at higher concentration. Treatment with the effluent also resulted in increased activity levels of antioxidant enzymes, such as superoxide dismutase (14.58 units/g fresh weight for 50 % and 24.57 units/g fresh weight for 100 %) and catalase (0.963 units/g fresh weight for 50 % and 1.263 units/g fresh weight for 100 %). Furthermore, heavy metal content was determined using atomic absorption spectrometry. These results indicated that A. platensis has the ability to combat heavy metal stress by the induction of antioxidant enzymes demonstrating its potential usefulness in phycoremediation of tannery effluent.
Determination of heavy metals and halogens in plastics from electric and electronic waste.

PubMed

Dimitrakakis, Emmanouil; Janz, Alexander; Bilitewski, Bernd; Gidarakos, Evangelos

2009-10-01

The presence of hazardous substances and preparations in small waste electrical and electronic equipment (sWEEE) found in the residual household waste stream of the city of Dresden, Germany has been investigated. The content of sWEEE plastics in heavy metals and halogens is determined using handheld X-ray fluorescence analysis (HXRF), elemental analysis by means of atomic absorption spectrometry (AAS) and ion exchange chromatography (IEC). Mean value of results for heavy metals in samples (n=51) by AAS are 17.4 mg/kg for Pb, 5.7 mg/kg for Cd, 8.4 mg/kg for Cr. The mass fraction of an additive as shown by HXRF (n=161) can vary over a wide range. Precise deductions as regards sWEEE plastics content in hazardous substances and preparations cannot be made. Additional research would be expedient regarding the influence of hazardous substances to recycling processes, in particular regarding the contamination of clean fractions in the exit streams of a WEEE treatment plant. Suitable standards for calibrating HXRF for use on EEE plastics or complex electr(on)ic components do not exist and should be developed.
Optically stimulated slowing of polar heavy-atom molecules with a constant beat phase

NASA Astrophysics Data System (ADS)

Yin, Yanning; Xu, Supeng; Xia, Meng; Xia, Yong; Yin, Jianping

2018-04-01

Polar heavy-atom molecules have been well recognized as promising candidates for precision measurements and tests of fundamental physics. A much slower molecular beam to increase the interaction time should lead to a more sensitive measurement. Here we theoretically demonstrate the possibility of the stimulated longitudinal slowing of heavy-atom molecules by the coherent optical bichromatic force with a constant beat phase. Taking the YbF meolecule as an example, we show that a rapid and short-distance deceleration of heavy molecules by a phase-compensation method is feasible with moderate conditions. A molecular beam of YbF with a forward velocity of 120 m/s can be decelerated below 10 m/s within a distance of 3.5 cm and with a laser irradiance for each traveling wave of 107.2 W/cm 2 . Our proposed slowing method could be a promising approach to break through the space constraint or the limited capture efficiency of molecules loadable into a magneto-optical trap in traditional deceleration schemes, opening the possibility for a significant improvement of the precision measurement sensitivity.
Several methods to determine heavy metals in the human brain

NASA Astrophysics Data System (ADS)

Andrási, Erzsébet; Igaz, Sarolta; Szoboszlai, Norbert; Farkas, Éva; Ajtony, Zsolt

1999-05-01

The determination of naturally occurring heavy metals in various parts of the human brain is discussed. The patients had no diseases in their central nervous systems (five individuals, mean age 70 years). Twenty brain parts were selected from both hemispheres. The analysis was carried out by graphite furnace atomic absorption spectrometry, inductively coupled plasma atomic emission spectrometry and instrumental neutron activation analysis methods. Accuracy and precision of the applied techniques were tested by using standard reference materials. Two digestion methods were used to dissolve the brain samples for ICP-AES and GF-AAS. One was performed in a Parr-bomb and the second in a microwave oven. The present results show a non-homogeneous distribution of the essential elements (Cu, Fe, Mn, Zn) in normal human brain. Corresponding regions in both hemispheres showed an almost identical concentration of these elements. In the case of toxic elements (Pb, Cd) an average value in different brain regions can not be established because of the high variability of individual data. This study indicates that beside differences in Pb and Cd intake with foods or cigarette smoke inhalation, the main factors of the high inter-individual variability of these element concentrations in human brain parts may be a marked difference in individual elimination or accumulation capabilities.
Towards phasing using high X-ray intensity

DOE PAGES

Galli, Lorenzo; Son, Sang -Kil; Barends, Thomas R. M.; ...

2015-09-30

X-ray free-electron lasers (XFELs) show great promise for macromolecular structure determination from sub-micrometre-sized crystals, using the emerging method of serial femtosecond crystallography. The extreme brightness of the XFEL radiation can multiply ionize most, if not all, atoms in a protein, causing their scattering factors to change during the pulse, with a preferential `bleaching' of heavy atoms. This paper investigates the effects of electronic damage on experimental data collected from a Gd derivative of lysozyme microcrystals at different X-ray intensities, and the degree of ionization of Gd atoms is quantified from phased difference Fourier maps. In conclusion, a pattern sorting schememore » is proposed to maximize the ionization contrast and the way in which the local electronic damage can be used for a new experimental phasing method is discussed.« less
Direct pair production in heavy-ion--atom collisions

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

Anholt, R.; Jakubassa-Amundsen, D.H.; Amundsen, P.A.

1983-02-01

Direct pair production in approx.5-MeV/amu heavy-ion--atom collisions with uranium target atoms is calculated with the plane-wave Born approximation and the semiclassical approximation. Briggs's approximation is used to obtain the electron and positron wave functions. Since pair production involves high momentum transfer q from the moving projectile to the vacuum, use is made of a high-q approximation to greatly simplify the numerical computations. Coulomb deflection of the projectile, the effect of finite nuclear size on the elec- tronic wave functions, and the energy loss by the projectile exciting the pair are all taken into account in these calculations.
High-accuracy mass spectrometry for fundamental studies.

PubMed

Kluge, H-Jürgen

2010-01-01

Mass spectrometry for fundamental studies in metrology and atomic, nuclear and particle physics requires extreme sensitivity and efficiency as well as ultimate resolving power and accuracy. An overview will be given on the global status of high-accuracy mass spectrometry for fundamental physics and metrology. Three quite different examples of modern mass spectrometric experiments in physics are presented: (i) the retardation spectrometer KATRIN at the Forschungszentrum Karlsruhe, employing electrostatic filtering in combination with magnetic-adiabatic collimation-the biggest mass spectrometer for determining the smallest mass, i.e. the mass of the electron anti-neutrino, (ii) the Experimental Cooler-Storage Ring at GSI-a mass spectrometer of medium size, relative to other accelerators, for determining medium-heavy masses and (iii) the Penning trap facility, SHIPTRAP, at GSI-the smallest mass spectrometer for determining the heaviest masses, those of super-heavy elements. Finally, a short view into the future will address the GSI project HITRAP at GSI for fundamental studies with highly-charged ions.
[Survey and evaluation of heavy metal in the major vegetables in Shaanxi Province].

PubMed

Nie, Xiaoling; Cheng, Guoxia; Wang, Minjuan; Wang, Caixia; Du, Kejun

2015-09-01

To evaluate the contamination condition of the Pb, Cd, Hg and As in ten kinds of vegetables in Shaanxi Province. The Pb and Cd contents were determined by inductively coupled plasma mass spectrometry, and the As contents were determined by hydride generation-atomic fluorescence spectrometry, and the Hg contents were determined by mercury vapourmeter. One factor contamination index was employed to evaluate the metal pollution situation of different types of vegetables. Moreover, the health risk after intake of those heavy metals through vegetables were described. In ten kinds of vegetables of Shaanxi Province, the Pb contents in cowpea reached the alertness level, while the contents of Cd, Hg and As were below the safety level. What' s more, the contents of the Pb, Cd, Hg and As were below the safety level in other nine vegetables, and the over standard rate of were Hg > Pb > Cd > As. The contamination extents of Pb, Cd, Hg and As in ten kinds of vegetables in Shaanxi Province were low.
Separation, identification and quantification of carotenoids and chlorophylls in dietary supplements containing Chlorella vulgaris and Spirulina platensis using High Performance Thin Layer Chromatography.

PubMed

Hynstova, Veronika; Sterbova, Dagmar; Klejdus, Borivoj; Hedbavny, Josef; Huska, Dalibor; Adam, Vojtech

2018-01-30

In this study, 14 commercial products (dietary supplements) containing alga Chlorella vulgaris and cyanobacteria Spirulina platensis, originated from China and Japan, were analysed. UV-vis spectrophotometric method was applied for rapid determination of chlorophylls, carotenoids and pheophytins; as degradation products of chlorophylls. High Performance Thin-Layer Chromatography (HPTLC) was used for effective separation of these compounds, and also Atomic Absorption Spectrometry for determination of heavy metals as indicator of environmental pollution. Based on the results obtained from UV-vis spectrophotometric determination of photosynthetic pigments (chlorophylls and carotenoids), it was confirmed that Chlorella vulgaris contains more of all these pigments compared to the cyanobacteria Spirulina platensis. The fastest mobility compound identified in Chlorella vulgaris and Spirulina platensis using HPTLC method was β-carotene. Spectral analysis and standard calibration curve method were used for identification and quantification of separated substances on Thin-Layer Chromatographic plate. Quantification of copper (Cu 2+ , at 324.7 nm) and zinc (Zn 2+ , at 213.9nm) was performed using Flame Atomic Absorption Spectrometry with air-acetylene flame atomization. Quantification of cadmium (Cd 2+ , at 228.8 nm), nickel (Ni 2+ , at 232.0nm) and lead (Pb 2+ , at 283.3nm) by Electrothermal Graphite Furnace Atomic Absorption Spectrometry; and quantification of mercury (Hg 2+ , at 254nm) by Cold Vapour Atomic Absorption Spectrometry. Copyright © 2017 Elsevier B.V. All rights reserved.
Studies on heavy charged particle interaction, water equivalence and Monte Carlo simulation in some gel dosimeters, water, human tissues and water phantoms

NASA Astrophysics Data System (ADS)

Kurudirek, Murat

2015-09-01

Some gel dosimeters, water, human tissues and water phantoms were investigated with respect to their radiological properties in the energy region 10 keV-10 MeV. The effective atomic numbers (Zeff) and electron densities (Ne) for some heavy charged particles such as protons, He ions, B ions and C ions have been calculated for the first time for Fricke, MAGIC, MAGAT, PAGAT, PRESAGE, water, adipose tissue, muscle skeletal (ICRP), muscle striated (ICRU), plastic water, WT1 and RW3 using mass stopping powers from SRIM Monte Carlo software. The ranges and straggling were also calculated for the given materials. Two different set of mass stopping powers were used to calculate Zeff for comparison. The water equivalence of the given materials was also determined based on the results obtained. The Monte Carlo simulation of the charged particle transport was also done using SRIM code. The heavy ion distribution along with its parameters were shown for the given materials for different heavy ions. Also the energy loss and damage events in water when irradiated with 100 keV heavy ions were studied in detail.
Ion optical design of a collinear laser-negative ion beam apparatus.

PubMed

Diehl, C; Wendt, K; Lindahl, A O; Andersson, P; Hanstorp, D

2011-05-01

An apparatus for photodetachment studies on atomic and molecular negative ions of medium up to heavy mass (M ≃ 500) has been designed and constructed. Laser and ion beams are merged in the apparatus in a collinear geometry and atoms, neutral molecules and negative ions are detected in the forward direction. The ion optical design and the components used to optimize the mass resolution and the transmission through the extended field-free interaction region are described. A 90° sector field magnet with 50 cm bending radius in combination with two slits is used for mass dispersion providing a resolution of M∕ΔM≅800 for molecular ions and M∕ΔM≅400 for atomic ions. The difference in mass resolution for atomic and molecular ions is attributed to different energy distributions of the sputtered ions. With 1 mm slits, transmission from the source through the interaction region to the final ion detector was determined to be about 0.14%.
Heavy ion action on single cells: Cellular inactivation capability of single accelerated heavy ions

NASA Technical Reports Server (NTRS)

Kost, M.; Pross, H.-D.; Russmann, C.; Schneider, E.; Kiefer, J.; Kraft, G.; Lenz, G.; Becher, W.

1994-01-01

Heavy ions (HZE-particles) constitute an important part of radiation in space. Although their number is small the high amount of energy transferred by individual particles may cause severe biological effects. Their investigation requires special techniques which were tested by experiments performed at the UNILAC at the GSI (Darmstadt). Diploid yeast was used which is a suitable eucaryotic test system because of its resistance to extreme conditions like dryness and vacuum. Cells were placed on nuclear track detector foils and exposed to ions of different atomic number and energy. To assess the action of one single ion on an individual cell, track parameters and the respective colony forming abilities (CFA) were determined with the help of computer aided image analysis. There is mounting evidence that not only the amount of energy deposited along the particle path, commonly given by the LET, is of importance but also the spatial problem of energy deposition at a submicroscopical scale. It is virtually impossible to investigate track structure effects in detail with whole cell populations and (globally applied) high particle fluences. It is, therefore, necessary to detect the action of simple ions in individual cells. The results show that the biological action depends on atomic number and specific energy of the impinging ions, which can be compared with model calculations of recent track structure models.
Heavy metals in surface sediments of the Jialu River, China: their relations to environmental factors.

PubMed

Fu, Jie; Zhao, Changpo; Luo, Yupeng; Liu, Chunsheng; Kyzas, George Z; Luo, Yin; Zhao, Dongye; An, Shuqing; Zhu, Hailiang

2014-04-15

This work investigated heavy metal pollution in surface sediments of the Jialu River, China. Sediment samples were collected at 19 sites along the river in connection with field surveys and the total concentrations were determined using atomic fluorescence spectrometer and inductively coupled plasma optical emission spectrometer. Sediment samples with higher metal concentrations were collected from the upper reach of the river, while sediments in the middle and lower reaches had relatively lower metal concentrations. Multivariate techniques including Pearson correlation, hierarchical cluster and principal components analysis were used to evaluate the metal sources. The ecological risk associated with the heavy metals in sediments was rated as moderate based on the assessments using methods of consensus-based Sediment Quality Guidelines, Potential Ecological Risk Index and Geo-accumulation Index. The relations between heavy metals and various environmental factors (i.e., chemical properties of sediments, water quality indices and aquatic organism indices) were also studied. Nitrate nitrogen, total nitrogen, and total polycyclic aromatic hydrocarbons concentrations in sediments showed a co-release behavior with heavy metals. Ammonia nitrogen, total nitrogen, orthophosphate, total phosphate and permanganate index in water were found to be related to metal sedimentation. Heavy metals in sediments posed a potential impact on the benthos community. Copyright © 2014 Elsevier B.V. All rights reserved.
Core-dependent and ligand-dependent relativistic corrections to the nuclear magnetic shieldings in MH4-n Y n (n = 0-4; M = Si, Ge, Sn, and Y = H, F, Cl, Br, I) model compounds.

PubMed

Maldonado, Alejandro F; Aucar, Gustavo A; Melo, Juan I

2014-09-01

The nuclear magnetic shieldings of Si, Ge, and Sn in MH(4-n) Y(n) (M = Si, Ge, Sn; Y = F, Cl, Br, I and n = 1-4) molecular systems are highly influenced by the substitution of one or more hydrogens by heavy-halogen atoms. We applied the linear response elimination of small components (LRESC) formalism to calculate those shieldings and learn whether including only a few of the leading relativistic correction terms is sufficient to be able to quantitatively reproduce the full relativistic value. It was observed that the nuclear magnetic shieldings change as the number of heavy halogen substituents and their weights vary, and the pattern of σ(M) generally does not exhibit the normal halogen dependence (NHD) behavior that can be seen in similar molecular systems containing carbon atoms. We also analyzed each relativistic correction afforded by the LRESC method and split them in two: core-dependent and ligand-dependent contributions; we then looked for the electronic mechanisms involved in the different relativistic effects and in the total relativistic value. Based on this analysis, we were able to study the electronic mechanism involved in a recently proposed relativistic effect, the "heavy atom effect on vicinal heavy atom" (HAVHA), in more detail. We found that the main electronic mechanism is the spin-orbit or σ p (T(3)) correction, although other corrections such as σ p (S(1)) and σ p (S(3)) are also important. Finally, we analyzed proton magnetic shieldings and found that, for molecules containing Sn as the central atom, σ(H) decreases as the number of heavy halogen substituents (of the same type: either F, Cl, or Br) increases, albeit at different rates for different halogens. σ(H) only increase as the number of halogen substituents increases if the halogen is iodine.
Application of 1-(2-pyridylazo)-2-naphthol-modified nanoporous silica as a technique in simultaneous trace monitoring and removal of toxic heavy metals in food and water samples.

PubMed

Abolhasani, Jafar; Behbahani, Mohammad

2015-01-01

Solid-phase extraction is one the most useful and efficient techniques for sample preparation, purification, cleanup, preconcentration, and determination of heavy metals at trace levels. In this paper, functionalized MCM-48 nanoporous silica with 1-(2-pyridylazo)-2-naphthol was applied for trace determination of copper, lead, cadmium, and nickel in water and seafood samples. The experimental conditions such as pH, sample and eluent flow rate, type, concentration and volume of the eluent, breakthrough volume, and effect of coexisting ions were optimized for efficient solid-phase extraction of trace heavy metals in different water and seafood samples. The content of solutions containing the mentioned heavy metals was determined by flame atomic absorption spectrometry (FAAS), and the limits of detection were 0.3, 0.4, 0.6, and 0.9 ng mL(-1) for cadmium, copper, nickel, and lead, respectively. Recoveries and precisions were >98.0 and <4%, respectively. The adsorption capacity of the modified nanoporous silica was 178 mg g(-1) for cadmium, 110 mg g(-1) for copper, 98 mg g(-1) for nickel, and 210 mg g(-1) for lead, respectively. The functionalized MCM-48 nanoporous silica with 1-(2-pyridylazo)-2-naphthol was characterized by thermogravimetry analysis (TGA), differential thermal analysis (DTA), transmission electron microscopy (TEM), Fourier transform infrared spectrometry (FT-IR), X-ray diffraction (XRD), elemental analysis (CHN), and N2 adsorption surface area measurement.
The determination of trace elements in crude oil and its heavy fractions by atomic spectrometry

NASA Astrophysics Data System (ADS)

Duyck, Christiane; Miekeley, Norbert; Porto da Silveira, Carmem L.; Aucélio, Ricardo Q.; Campos, Reinaldo C.; Grinberg, Patrícia; Brandão, Geisamanda P.

2007-09-01

A literature review on the determination of trace elements in crude oil and heavy molecular mass fractions (saturates, aromatics, resins and asphaltenes) by ICP-MS, ICP OES and AAS is presented. Metal occurrences, forms and distributions are examined as well as their implications in terms of reservoir geochemistry, oil refining and environment. The particular analytical challenges for the determination of metals in these complex matrices by spectrochemical techniques are discussed. Sample preparation based on ashing, microwave-assisted digestion and combustion decomposition procedures is noted as robust and long used. However, the introduction of non-aqueous solvents and micro-emulsions into inductively coupled plasmas is cited as a new trend for achieving rapid and accurate analysis. Separation procedures for operationally defined fractions in crude oil are more systematically applied for the observation of metal distributions and their implications. Chemical speciation is of growing interest, achieved by the coupling of high efficiency separation techniques (e.g., HPLC and GC) to ICP-MS instrumentation, which allows the simultaneous determination of multiple organometallic species of geochemical and environmental importance.
Phase contrast scanning transmission electron microscopy imaging of light and heavy atoms at the limit of contrast and resolution.

PubMed

Yücelen, Emrah; Lazić, Ivan; Bosch, Eric G T

2018-02-08

Using state of the art scanning transmission electron microscopy (STEM) it is nowadays possible to directly image single atomic columns at sub-Å resolution. In standard (high angle) annular dark field STEM ((HA)ADF-STEM), however, light elements are usually invisible when imaged together with heavier elements in one image. Here we demonstrate the capability of the recently introduced Integrated Differential Phase Contrast STEM (iDPC-STEM) technique to image both light and heavy atoms in a thin sample at sub-Å resolution. We use the technique to resolve both the Gallium and Nitrogen dumbbells in a GaN crystal in [[Formula: see text
Relativistic Confinement Resonances

NASA Astrophysics Data System (ADS)

Keating, David; Manson, Steven; Deshmukh, Pranawa

2017-04-01

Photoionization of confined atoms in a C60 fullerene have been under intense investigation in the recent years, in particular the confinement induced resonances, termed confinement resonances. The effects of the C60 potential are modeled by a static spherical well, with (in atomic units) inner radius r0 = 5.8, width Δ = 1.9, and depth U0 = -0.302, which is reasonable in the energy region well above the C60 plasmons. At very high Z, relativistic interactions become important contributors to even the qualitative nature of atomic properties; this is true for confined atomic properties as well. To explore the extent of these interactions, a theoretical study of several heavy atoms has been performed using the relativistic random phase approximation (RRPA) methodology. In order to determine which features in the photoionization cross section are due to relativity, calculations using the (nonrelativistic) random phase approximation with exchange method (RPAE) are performed for comparison. The existence of the second subshell of the spin-orbit-split doublets can induce new confinement resonances in the total cross section, which is the sum of the spin-orbit-split doublets, due to the shift in the doublet's threshold. Several examples for confined high-Z atoms are presented. Work supported by DOE and NSF.
Lanthanide/Actinide Opacities

NASA Astrophysics Data System (ADS)

Hungerford, Aimee; Fontes, Christopher J.

2018-06-01

Gravitational wave observations benefit from accompanying electromagnetic signals in order to accurately determine the sky positions of the sources. The ejecta of neutron star mergers are expected to produce such electromagnetic transients, called macronovae (e.g. the recent and unprecedented observation of GW170817). Characteristics of the ejecta include large velocity gradients and the presence of heavy r-process elements, which pose significant challenges to the accurate calculation of radiative opacities and radiation transport. Opacities include a dense forest of bound-bound features arising from near-neutral lanthanide and actinide elements. Here we present an overview of current theoretical opacity determinations that are used by neutron star merger light curve modelers. We will touch on atomic physics and plasma modeling codes that are used to generate these opacities, as well as the limited body of laboratory experiments that may serve as points of validation for these complex atomic physics calculations.
Nucleosynthesis: Stellar and Solar Abundances and Atomic Data

NASA Technical Reports Server (NTRS)

Cowan, John J.; Lawler, James E.; Sneden, Christopher; DenHartog, E. A.; Collier, Jason; Dodge, Homer L.

2006-01-01

Abundance observations indicate the presence of often surprisingly large amounts of neutron capture (i.e., s- and r-process) elements in old Galactic halo and globular cluster stars. These observations provide insight into the nature of the earliest generations of stars in the Galaxy the progenitors of the halo stars responsible for neutron-capture synthesis. Comparisons of abundance trends can be used to understand the chemical evolution of the Galaxy and the nature of heavy element nucleosynthesis. In addition age determinations, based upon long-lived radioactive nuclei abundances, can now be obtained. These stellar abundance determinations depend critically upon atomic data. Improved laboratory transition probabilities have been recently obtained for a number of elements. These new gf values have been used to greatly refine the abundances of neutron-capture elemental abundances in the solar photosphere and in very metal-poor Galactic halo stars. The newly determined stellar abundances are surprisingly consistent with a (relative) Solar System r-process pattern, and are also consistent with abundance predictions expected from such neutron-capture nucleosynthesis.

An ab initio MO study of heavy atom effects on the zero-field splitting tensors of high-spin nitrenes: how the spin-orbit contributions are affected.

PubMed

Sugisaki, Kenji; Toyota, Kazuo; Sato, Kazunobu; Shiomi, Daisuke; Kitagawa, Masahiro; Takui, Takeji

2014-05-21

The CASSCF and the hybrid CASSCF-MRMP2 methods are applied to the calculations of spin-spin and spin-orbit contributions to the zero-field splitting tensors (D tensors) of the halogen-substituted spin-septet 2,4,6-trinitrenopyridines, focusing on the heavy atom effects on the spin-orbit term of the D tensors (D(SO) tensors). The calculations reproduced experimentally determined |D| values within an error of 15%. Halogen substitutions at the 3,5-positions are less influential in the spin-spin dipolar (D(SS)) term of 2,4,6-trinitrenopyridines, although the D(SO) terms are strongly affected by the introduction of heavier halogens. The absolute sign of the D(SO) value (D = D(ZZ) - (D(XX) + D(YY))/2) of 3,5-dibromo derivative 3 is predicted to be negative, which contradicts the Pederson-Khanna (PK) DFT result previously reported. The large negative contributions to the D(SO) value of 3 arise from the excited spin-septet states ascribed mainly to the excitations of in-plane lone pair of bromine atoms → SOMO of π nature. The importance of the excited states involving electron transitions from the lone pair orbital of the halogen atom is also confirmed in the D(SO) tensors of halogen-substituted para-phenylnitrenes. A new scheme based on the orbital region partitioning is proposed for the analysis of the D(SO) tensors as calculated by means of the PK-DFT approach.
Heavy-Atom Tunneling Calculations in Thirteen Organic Reactions: Tunneling Contributions are Substantial, and Bell's Formula Closely Approximates Multidimensional Tunneling at ≥250 K.

PubMed

Doubleday, Charles; Armas, Randy; Walker, Dana; Cosgriff, Christopher V; Greer, Edyta M

2017-10-09

Multidimensional tunneling calculations are carried out for 13 reactions, to test the scope of heavy-atom tunneling in organic chemistry, and to check the accuracy of one-dimensional tunneling models. The reactions include pericyclic, cycloaromatization, radical cyclization and ring opening, and S N 2. When compared at the temperatures that give the same effective rate constant of 3×10 -5 s -1 , tunneling accounts for 25-95 % of the rate in 8 of the 13 reactions. Values of transmission coefficients predicted by Bell's formula, κ Bell , agree well with multidimensional tunneling (canonical variational transition state theory with small curvature tunneling), κ SCT . Mean unsigned deviations of κ Bell vs. κ SCT are 0.08, 0.04, 0.02 at 250, 300 and 400 K. This suggests that κ Bell is a useful first choice for predicting transmission coefficients in heavy-atom tunnelling. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Atomic Data Revisions for Transitions Relevant to Observations of Interstellar, Circumgalactic, and Intergalactic Matter

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

Cashman, Frances H.; Kulkarni, Varsha P.; Kisielius, Romas

2017-05-01

Measurements of element abundances in galaxies from astrophysical spectroscopy depend sensitively on the atomic data used. With the goal of making the latest atomic data accessible to the community, we present a compilation of selected atomic data for resonant absorption lines at wavelengths longward of 911.753 Å (the H i Lyman limit), for key heavy elements (heavier than atomic number 5) of astrophysical interest. In particular, we focus on the transitions of those ions that have been observed in the Milky Way interstellar medium (ISM), the circumgalactic medium (CGM) of the Milky Way and/or other galaxies, and the intergalactic mediummore » (IGM). We provide wavelengths, oscillator strengths, associated accuracy grades, and references to the oscillator strength determinations. We also attempt to compare and assess the recent oscillator strength determinations. For about 22% of the lines that have updated oscillator strength values, the differences between the former values and the updated ones are ≳0.1 dex. Our compilation will be a useful resource for absorption line studies of the ISM, as well as studies of the CGM and IGM traced by sight lines to quasars and gamma-ray bursts. Studies (including those enabled by future generations of extremely large telescopes) of absorption by galaxies against the light of background galaxies will also benefit from our compilation.« less
The Extent of Heavy Metal Pollution and Their Potential Health Risk in Topsoils of the Massively Urbanized District of Shanghai.

PubMed

Jaffar, Syed Taseer Abbas; Luo, Fan; Ye, Rong; Younas, Hassan; Hu, Xue-Feng; Chen, Long-Zhu

2017-10-01

Urbanization and industrialization increase the concentrations of heavy metals in soils, which affect human health. A total of 127 topsoil samples were collected from the massively urbanized and industrialized district of Shanghai: Baoshan District. The sampling sites were isolated based on the land-use practice: industrial area, roadside area, residential area, and agricultural area. The absolute concentrations of heavy metals (Zn, Cr, Ni, Mn, Cu, Pb, and Cd) were determined using atomic absorption spectrometry and compared with Shanghai and the National soil background values. The geoaccumulation index (Igeo) and Nemerow pollution index were used to determine the existence and severity of the pollution of heavy metals. Enrichment factor (EF) analysis, spatial variability of pollution, and multivariate statistical analyses also were employed to determine the anthropogenic loading of heavy metals, their spatial dependency, and correlation among their sources, respectively. Moreover, potential ecological risk and human health risk [carcinogenic risk (RI) and noncarcinogenic hazard (HI)] were evaluated. The average concentration of all the metals (accounted as 229, 128, 56, 719, 55, 119, and 0.3 mg kg -1 for Zn, Cr, Ni, Mn, Cu, Pb, and Cd, respectively) was many folds higher than the background values. The indices depicted that the pollution exists in all the sites and severity decreases in the following order: industrial soils > roadside soil > residential soils > agricultural soils. However, Zn, Pb, and Cd showed high levels of pollution in all the soils. The EF values suggested that the majority of heavy metals are anthropogenically loaded; spatial variability showed that the pollution is more concentrated in Songnan town; Pearson's correlation, principal component analysis (PCA), and cluster analysis suggested different sources of origin for the majority of the heavy metals. RI of Cr and Pb ranged between 2.8E-04 and 2.7E-07. However, HI was site-specific (only for Cr, Pb, Mn), and most of the sites were in Songnan town. This study could be used as a significant piece of information for management purposes to prevent heavy metal pollution and to protect human health.
Cu determination in crude oil distillation products by atomic absorption and inductively coupled plasma mass spectrometry after analyte transfer to aqueous solution

NASA Astrophysics Data System (ADS)

Kowalewska, Zofia; Ruszczyńska, Anna; Bulska, Ewa

2005-03-01

Cu was determined in a wide range of petroleum products from crude oil distillation using flame atomic absorption spectrometry (FAAS), electrothermal atomic absorption spectrometry (ETAAS) and inductively coupled plasma mass spectrometry (ICP-MS). Different procedures of sample preparation were evaluated: (i) mineralization with sulfuric acid in an open system, (ii) mineralization in a closed microwave system, (iii) combustion in hydrogen-oxygen flame in the Wickbold's apparatus, (iv) matrix evaporation followed by acid dissolution, and (v) acidic extraction. All the above procedures led to the transfer of the analyte into an aqueous solution for the analytical measurement step. It was found that application of FAAS was limited to the analysis of the heaviest petroleum products of high Cu content. In ICP-MS, the use of internal reference method (with Rh or In as internal reference element) was required to eliminate the matrix effects in the analysis of extracts and the concentrated solutions of mineralized heavy petroleum products. The detection limits (in original samples) were equal to, respectively, 10, 86, 3.3, 0.9 and 0.4 ng g - 1 in procedures i-v with ETAAS detection and 10, 78, 1.1 and 0.5 ng g - 1 in procedures i-iii and v with ICP-MS detection. The procedures recommended here were validated by recovery experiments, certified reference materials analysis and comparison of results, obtained for a given sample, in different ways. The Cu content in the analyzed samples was: 50-110 ng g - 1 in crude oil, < 0.4-6 ng g - 1 in gasoline, < 0.5-2 ng g - 1 in atmospheric oil, < 6-100 ng g - 1 in heavy vacuum oil and 140-300 ng g - 1 in distillation residue.
Evaluation of heavy metal concentrations of edible wild-grown mushrooms from China.

PubMed

Wang, Xuemei; Liu, Honggao; Zhang, Ji; Li, Tao; Wang, Yuanzhong

2017-03-04

The heavy metal contents (Co, Cu, Fe, Mn, Ni, and Zn) of eight species of wild edible mushrooms from China were determined. The analyses were performed using inductively coupled plasma atomic emission spectrophotometry after microwave digestion. The contents of Co, Cu, Fe, Mn, Ni, and Zn in caps of mushroom samples were 0.7-7.2, 16.2-70.4, 371-1315, 12.5-29.8, 7.1-58.5, and 77.8-187.4 mg kg -1 dry matter (dm), respectively, while considerable differences were found to be 1.8-25.9, 9.8-36.3, 288-6762, 13.3-103.9, 5.9-78.7, and 38.7-118 mg kg -1 dm for stipes. The results indicated that higher levels of Co, Fe, and Ni were found in the mushrooms samples analyzed. Zinc and manganese levels were similar to previous reports, whereas Cu was lower than literature values. Correlation analysis suggested that significant correlations were found between the minerals determined and the greatest amount of contamination is associated with Co, Mn, Ni, and Fe. The results of this study indicate that heavy metal contents in mushroom species are mainly related to the mineral resources of sampling sites.
Quantitative analysis of polypeptide pharmaceuticals by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

PubMed

Amini, Ahmad; Nilsson, Elin

2008-02-13

An accurate method based on matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) has been developed for quantitative analysis of calcitonin and insulin in different commercially available pharmaceutical products. Tryptic peptides derived from these polypeptides were chemically modified at their C-terminal lysine-residues with 2-methoxy-4,5-dihydro-imidazole (light tagging) as standard and deuterated 2-methoxy-4,5-dihydro-imidazole (heavy tagging) as internal standard (IS). The heavy modified tryptic peptides (4D-Lys tag), differed by four atomic mass units from the corresponding light labelled counterparts (4H-Lys tag). The normalized peak areas (the ratio between the light and heavy tagged peptides) were used to construct a standard curve to determine the concentration of the analytes. The concentrations of calcitonin and insulin content of the analyzed pharmaceutical products were accurately determined, and less than 5% error was obtained between the present method and the manufacturer specified values. It was also found that the cysteine residues in CSNLSTCVLGK from tryptic calcitonin were converted to lanthionine by the loss of one sulfhydryl group during the labelling procedure.
Statistical clumped isotope signatures

PubMed Central

Röckmann, T.; Popa, M. E.; Krol, M. C.; Hofmann, M. E. G.

2016-01-01

High precision measurements of molecules containing more than one heavy isotope may provide novel constraints on element cycles in nature. These so-called clumped isotope signatures are reported relative to the random (stochastic) distribution of heavy isotopes over all available isotopocules of a molecule, which is the conventional reference. When multiple indistinguishable atoms of the same element are present in a molecule, this reference is calculated from the bulk (≈average) isotopic composition of the involved atoms. We show here that this referencing convention leads to apparent negative clumped isotope anomalies (anti-clumping) when the indistinguishable atoms originate from isotopically different populations. Such statistical clumped isotope anomalies must occur in any system where two or more indistinguishable atoms of the same element, but with different isotopic composition, combine in a molecule. The size of the anti-clumping signal is closely related to the difference of the initial isotope ratios of the indistinguishable atoms that have combined. Therefore, a measured statistical clumped isotope anomaly, relative to an expected (e.g. thermodynamical) clumped isotope composition, may allow assessment of the heterogeneity of the isotopic pools of atoms that are the substrate for formation of molecules. PMID:27535168
Heavy Metal Contents and Physical Parameters of Aegiceras corniculatum, Brassica juncea, and Litchi chinensis Honeys from Bangladesh

PubMed Central

Sarker, Nandita; Chowdhury, Muhammed Alamgir Zaman; Fakhruddin, Abu Naieum Muhammad; Fardous, Zeenath; Moniruzzaman, Mohammed; Gan, Siew Hua

2015-01-01

The present study was undertaken to determine the heavy metal levels and the physicochemical parameters (pH, electrical conductivity (EC), and ash, moisture, and total sugar content) of honeys from Bangladesh. Three different floral honeys were investigated, namely, khalsi (Aegiceras corniculatum), mustard (Brassica juncea), and litchi (Litchi chinensis) honeys. The heavy metals in the honeys were determined by using a High Temperature Dry Oxidation method followed by Atomic Absorption Spectroscopy. The mean pH, EC, and ash, moisture, and total sugar contents of the investigated honeys were 3.6, 0.51 mS/cm, 0.18%, 18.83%, and 68.30%, respectively. Iron was the most abundant among all the investigated heavy metals, ranging from 13.51 to 15.44 mg/kg. The mean concentrations of Mn and Zn in the investigated honeys were 0.28 mg/kg and 2.99 mg/kg, respectively. Cd was below the detection limit, and lead was found in some honey samples, but their contents were below the recommended Maximum Acceptable Level. Cr was also found in all of the samples, but its concentration was within the limit. The physicochemical analysis of the honey samples yielded levels within the limits set by the international honey legislation, indicating that the honey samples were of good quality and had acceptable values for maturity, purity, and freshness. PMID:26618176
Heavy Metal Contents and Physical Parameters of Aegiceras corniculatum, Brassica juncea, and Litchi chinensis Honeys from Bangladesh.

PubMed

Sarker, Nandita; Chowdhury, Muhammed Alamgir Zaman; Fakhruddin, Abu Naieum Muhammad; Fardous, Zeenath; Moniruzzaman, Mohammed; Gan, Siew Hua

2015-01-01

The present study was undertaken to determine the heavy metal levels and the physicochemical parameters (pH, electrical conductivity (EC), and ash, moisture, and total sugar content) of honeys from Bangladesh. Three different floral honeys were investigated, namely, khalsi (Aegiceras corniculatum), mustard (Brassica juncea), and litchi (Litchi chinensis) honeys. The heavy metals in the honeys were determined by using a High Temperature Dry Oxidation method followed by Atomic Absorption Spectroscopy. The mean pH, EC, and ash, moisture, and total sugar contents of the investigated honeys were 3.6, 0.51 mS/cm, 0.18%, 18.83%, and 68.30%, respectively. Iron was the most abundant among all the investigated heavy metals, ranging from 13.51 to 15.44 mg/kg. The mean concentrations of Mn and Zn in the investigated honeys were 0.28 mg/kg and 2.99 mg/kg, respectively. Cd was below the detection limit, and lead was found in some honey samples, but their contents were below the recommended Maximum Acceptable Level. Cr was also found in all of the samples, but its concentration was within the limit. The physicochemical analysis of the honey samples yielded levels within the limits set by the international honey legislation, indicating that the honey samples were of good quality and had acceptable values for maturity, purity, and freshness.
Heavy Elements and Cool Stars

NASA Technical Reports Server (NTRS)

Wahlgren, Glenn M.; Carpenter, Kenneth G.; Norris, Ryan P.

2008-01-01

We report on progress in the analysis of high-resolution near-IR spectra of alpha Orionis (M2 Iab) and other cool, luminous stars. Using synthetic spectrum techniques, we search for atomic absorption lines in the stellar spectra and evaluate the available line parameter data for use in our abundance analyses. Our study concentrates on the post iron-group elements copper through zirconium as a means of investigating the slow neutron-capture process of nucleosynthesis in massive stars and the mechanisms that transport recently processed material up into the photospheric region. We discuss problems with the atomic data and model atmospheres that need to be addressed before theoretically derived elemental abundances from pre-supernova nucleosynthesis calculations can be tested by comparison with abundances determined from observations of cool, massive stars.
Tailoring Thermal Conductivity of Single-stranded Carbon-chain Polymers through Atomic Mass Modification

PubMed Central

Liao, Quanwen; Zeng, Lingping; Liu, Zhichun; Liu, Wei

2016-01-01

Tailoring the thermal conductivity of polymers is central to enlarge their applications in the thermal management of flexible integrated circuits. Progress has been made over the past decade by fabricating materials with various nanostructures, but a clear relationship between various functional groups and thermal properties of polymers remains to be established. Here, we numerically study the thermal conductivity of single-stranded carbon-chain polymers with multiple substituents of hydrogen atoms through atomic mass modification. We find that their thermal conductivity can be tuned by atomic mass modifications as revealed through molecular dynamics simulations. The simulation results suggest that heavy homogeneous substituents do not assist heat transport and trace amounts of heavy substituents can in fact hinder heat transport substantially. Our analysis indicates that carbon chain has the biggest contribution (over 80%) to the thermal conduction in single-stranded carbon-chain polymers. We further demonstrate that atomic mass modifications influence the phonon bands of bonding carbon atoms, and the discrepancies of phonon bands between carbon atoms are responsible for the remarkable drops in thermal conductivity and large thermal resistances in carbon chains. Our study provides fundamental insight into how to tailor the thermal conductivity of polymers through variable substituents. PMID:27713563
Ionization of Atoms by Slow Heavy Particles, Including Dark Matter.

PubMed

Roberts, B M; Flambaum, V V; Gribakin, G F

2016-01-15

Atoms and molecules can become ionized during the scattering of a slow, heavy particle off a bound electron. Such an interaction involving leptophilic weakly interacting massive particles (WIMPs) is a promising possible explanation for the anomalous 9σ annual modulation in the DAMA dark matter direct detection experiment [R. Bernabei et al., Eur. Phys. J. C 73, 2648 (2013)]. We demonstrate the applicability of the Born approximation for such an interaction by showing its equivalence to the semiclassical adiabatic treatment of atomic ionization by slow-moving WIMPs. Conventional wisdom has it that the ionization probability for such a process should be exponentially small. We show, however, that due to nonanalytic, cusplike behavior of Coulomb functions close to the nucleus this suppression is removed, leading to an effective atomic structure enhancement. We also show that electron relativistic effects actually give the dominant contribution to such a process, enhancing the differential cross section by up to 1000 times.
HITRAP: A Facility for Experiments with Trapped Highly Charged Ions

NASA Astrophysics Data System (ADS)

Quint, W.; Dilling, J.; Djekic, S.; Häffner, H.; Hermanspahn, N.; Kluge, H.-J.; Marx, G.; Moore, R.; Rodriguez, D.; Schönfelder, J.; Sikler, G.; Valenzuela, T.; Verdú, J.; Weber, C.; Werth, G.

2001-01-01

HITRAP is a planned ion trap facility for capturing and cooling of highly charged ions produced at GSI in the heavy-ion complex of the UNILAC-SIS accelerators and the ESR storage ring. In this facility heavy highly charged ions up to uranium will be available as bare nuclei, hydrogen-like ions or few-electron systems at low temperatures. The trap for receiving and studying these ions is designed for operation at extremely high vacuum by cooling to cryogenic temperatures. The stored highly charged ions can be investigated in the trap itself or can be extracted from the trap at energies up to about 10 keV/q. The proposed physics experiments are collision studies with highly charged ions at well-defined low energies (eV/u), high-accuracy measurements to determine the g-factor of the electron bound in a hydrogen-like heavy ion and the atomic binding energies of few-electron systems, laser spectroscopy of HFS transitions and X-ray spectroscopy.
Heavy Metal Detoxification by Different Bacillus Species Isolated from Solar Salterns

PubMed Central

Syed, Shameer; Chinthala, Paramageetham

2015-01-01

The biosorption mechanism is an alternative for chemical precipitation and ultrafiltration which have been employed to treat heavy metal contamination with a limited success. In the present study, three species of Bacillus which were isolated from solar salterns were screened for their detoxification potential of the heavy metals, lead, chromium, and copper, by biosorption. Biosorption potential of each isolate was determined by Atomic Absorption Spectroscopy (AAS), Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), and Energy Dispersive Spectroscopy (EDS) as the amount of metal present in the medium after the treatment with the isolates. Bacterial isolates, Bacillus licheniformis NSPA5, Bacillus cereus NSPA8, and Bacillus subtilis NSPA13, showed significant level of lead biosorption with maximum of 87–90% by Bacillus cereus NSPA8. The biosorption of copper and chromium was relatively low in comparison with lead. With the obtained results, we have concluded that the bacterial isolates are potential agents to treat metal contamination in more efficient and ecofriendly manner. PMID:26525498
The dispersion of heavy metals in the vicinity of Britannia Mine, British Columbia, Canada.

PubMed

Wilson, Bob; Lang, Brennan; Pyatt, F Brian

2005-03-01

Britannia Mine in British Columbia, Canada, is a major source of copper and other heavy metal pollutants, which enter the sea at Howe Sound. This investigation aims to determine whether there is sufficient Cd, Cu, Pb, and Zn, in the terrestrial environment surrounding the mine to suggest that dispersion and subsequent bioaccumulation has occurred in the past and continues. Samples of spoil, vegetation, and water were collected in January 2003 from areas at sea level and up to an altitude of 790 m. The samples of soil and vegetation were digested with aqua regia. The subsequent extracts and water samples were analyzed using flame atomic absorption spectrophotometry. The target metal concentrations were found to be much higher on the hillside spoil tips than on the seashore where the ore concentrators had formerly been located. The dispersion of heavy metals into the surrounding biosphere is discussed and further investigations into dispersion and partitioning within organisms including humans are suggested.
The use of epilithic Antarctic lichens (Usnea aurantiacoatra and U. antartica) to determine deposition patterns of heavy metals in the Shetland Islands, Antarctica.

PubMed

Poblet, A; Andrade, S; Scagliola, M; Vodopivez, C; Curtosi, A; Pucci, A; Marcovecchio, J

1997-11-27

Trace-metal contents were recorded for the epilithic antarctic lichens Usnea aurantiacoatra and U. antartica, sampled close to the Argentine scientific station 'Jubany' on '25 de Mayo' (King George) Island, in the Southern Shetland Archipelago (Antarctica). The corresponding heavy-metal levels have been measured through atomic absorption spectrophotometry, following internationally accepted analytical methods. The results obtained support the hypothesis that an atmospheric circulation of trace metals exists on the assessed area, and the activities developed at the different scientific stations located on this island would be a potential source of heavy metals to the evaluated environment. The geographical distribution of trace metals atmospherically transported in the area close to 'Jubany Station' was studied through the corresponding metal contents of the assessed lichens. Finally, the suitability of both analyzed lichen species, Usnea aurantiacoatra and U. antartica, as biological indicators for quantitative monitoring of airborne metals for this antarctic environment was recognized.
Characteristic of total suspended particulate (TSP) containing Pb and Zn at solid waste landfill

NASA Astrophysics Data System (ADS)

Budihardjo, M. A.; Noveandra, K.; Samadikun, B. P.

2018-05-01

Activities conducted at municipal solid waste landfills (MSWLs) potentially cause air pollution. Heavy vehicles in MSWLs release various pollutants that can have negative impacts for humans. One noticeable pollutant at MSWLs is airborne total suspended particulate (TSP) which may contain heavy metals such as Pb and Zn and can cause disease when inhaled by humans. In this study, TSP from a landfill in Semarang, Indonesia was collected and characterized to quantify the concentration of Pb and Zn. Meteorological factors (i.e. temperature, humidity and wind velocity) and landfill activities were considered as factors affecting pollutant concentrations. TSP was sampled using dust samplers while the concentrations of heavy metals in TSP were analyzed using an Atomic Absorption Spectrophotometer (AAS). Pb concentration ranged from 0.84 to 1.78 µg/m3 while Zn concentration was from 7.87 to 8.76 µg/m3. The levels of Pb were below the threshold specified by the Indonesian Government. Meanwhile, the threshold for Zn has not yet been determined.
Compositional analysis and depth profiling of thin film CrO{sub 2} by heavy ion ERDA and standard RBS: a comparison

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

Khamlich, S., E-mail: skhamlich@gmail.com; Department of Chemistry, Tshwane University of Technology, Private Bag X 680, Pretoria, 0001; The African Laser Centre, CSIR campus, P.O. Box 395, Pretoria

2012-08-15

Chromium dioxide (CrO{sub 2}) thin film has generated considerable interest in applied research due to the wide variety of its technological applications. It has been extensively investigated in recent years, attracting the attention of researchers working on spintronic heterostructures and in the magnetic recording industry. However, its synthesis is usually a difficult task due to its metastable nature and various synthesis techniques are being investigated. In this work a polycrystalline thin film of CrO{sub 2} was prepared by electron beam vaporization of Cr{sub 2}O{sub 3} onto a Si substrate. The polycrystalline structure was confirmed through XRD analysis. The stoichiometry andmore » elemental depth distribution of the deposited film were measured by ion beam nuclear analytical techniques heavy ion elastic recoil detection analysis (ERDA) and Rutherford backscattering spectrometry (RBS), which both have relative advantage over non-nuclear spectrometries in that they can readily provide quantitative information about the concentration and distribution of different atomic species in a layer. Moreover, the analysis carried out highlights the importance of complementary usage of the two techniques to obtain a more complete description of elemental content and depth distribution in thin films. - Graphical abstract: Heavy ion elastic recoil detection analysis (ERDA) and Rutherford backscattering spectrometry (RBS) both have relative advantage over non-nuclear spectrometries in that they can readily provide quantitative information about the concentration and distribution of different atomic species in a layer. Highlights: Black-Right-Pointing-Pointer Thin films of CrO{sub 2} have been grown by e-beam evaporation of Cr{sub 2}O{sub 3} target in vacuum. Black-Right-Pointing-Pointer The composition was determined by heavy ion-ERDA and RBS. Black-Right-Pointing-Pointer HI-ERDA and RBS provided information on the light and heavy elements, respectively.« less
Leachability of heavy metals from growth media containing source-separated municipal solid waste compost

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

Sawhney, B.L.; Bugbee, G.J.; Stilwell, D.E.

1994-07-01

The leaching of heavy metals in source-separated municipal solid waste (MSW) compost was determined by irrigation leaching of growth medium, admixed with varying amounts of compost, used for container grown plants. Perennial flowers (black-eyed Susan, Rudbeckia hirta L.) were grown in 2-L containers filled with the growth medium for a 10-wk period. Rainfall was supplemented with overhead irrigation to supply 2 cm of water per day. Leachates collected over each 2-wk period were analyzed for Cd, Cr, Cu, Ni, Pb, and Zn using atomic spectrometry. Concentrations of the heavy metals in the leachates increased with increasing proportions of MSW compostmore » in the growth medium, but decreased with time of leaching. Leaching of the metals occurred at relatively high concentrations initially, followed by continued leaching at low concentrations. The initial leaching of heavy metals is attributed to their soluble or exchangeable forms and the subsequent slow leaching to the solid compounds. The concentrations of the heavy metals remained below the current drinking water standards in all treatments throughout the leaching period. The results thus suggest that contamination of groundwater with heavy metals from source-separated MSW compost applied as a soil amendment should be negligible, as the low concentrations in the leachates leaving the surface soil would be further attenuated by the subsoil. 29 refs., 6 figs., 1 tab.« less

Heavy metals concentration in vegetables irrigated with contaminated and fresh water and estimation of their daily intakes in suburb areas of Hamadan, Iran.

PubMed

Seid-Mohammadi, Abdolmotaleb; Roshanaei, Ghodratollah; Asgari, Ghorban

2014-01-01

This study was conducted to estimate the level of heavy metals accumulate in vegetables irrigated with contaminated water compared with those irrigated with fresh water in Hamadan, west of Iran in 2012. Sixty samples of different vegetables i.e., parsley, tarragon, sweat basil and leek irrigated with contaminated water and thirty six samples from three different adjacent areas irrigated with fresh water as control were analyzed to determine heavy metals. The concentration of heavy metals i.e., lead, cadmium and chromium were achieved using atomic adsorption spectrophotometer. The mean concentration of lead, chromium and cadmium regardless of the kind of vegetables irrigated with contaminated water was 6.24, 1.57 and 0.15 mg/kg, respectively. Moreover, metals uptake differences by the vegetables were recognized to vegetable differences in tolerance to heavy metals. Based on the above concentrations the dietary intakes of metals through vegetables consumption were 0.004, 0.0008 and 6E-05 mg/day in infants for lead, chromium and cadmium, respectively. The high concentration of these heavy metals in some vegetables might be attributed due to the use of untreated sanitary and industrial wastewater by farmers for the irrigation of vegetable lands. Therefore, treating of these wastewater and bioremediation of excess metals from polluted vegetation land could be considered.
Atom-scale depth localization of biologically important chemical elements in molecular layers.

PubMed

Schneck, Emanuel; Scoppola, Ernesto; Drnec, Jakub; Mocuta, Cristian; Felici, Roberto; Novikov, Dmitri; Fragneto, Giovanna; Daillant, Jean

2016-08-23

In nature, biomolecules are often organized as functional thin layers in interfacial architectures, the most prominent examples being biological membranes. Biomolecular layers play also important roles in context with biotechnological surfaces, for instance, when they are the result of adsorption processes. For the understanding of many biological or biotechnologically relevant phenomena, detailed structural insight into the involved biomolecular layers is required. Here, we use standing-wave X-ray fluorescence (SWXF) to localize chemical elements in solid-supported lipid and protein layers with near-Ångstrom precision. The technique complements traditional specular reflectometry experiments that merely yield the layers' global density profiles. While earlier work mostly focused on relatively heavy elements, typically metal ions, we show that it is also possible to determine the position of the comparatively light elements S and P, which are found in the most abundant classes of biomolecules and are therefore particularly important. With that, we overcome the need of artificial heavy atom labels, the main obstacle to a broader application of high-resolution SWXF in the fields of biology and soft matter. This work may thus constitute the basis for the label-free, element-specific structural investigation of complex biomolecular layers and biological surfaces.
Geometrically frustrated magnetic structures of the heavy-fermion compound CePdAl studied by powder neutron diffraction

NASA Astrophysics Data System (ADS)

Dönni, A.; Ehlers, G.; Maletta, H.; Fischer, P.; Kitazawa, H.; Zolliker, M.

1996-12-01

The heavy-fermion compound CePdAl with ZrNiAl-type crystal structure (hexagonal space group 0953-8984/8/50/043/img8) was investigated by powder neutron diffraction. The triangular coordination symmetry of magnetic Ce atoms on site 3f gives rise to geometrical frustration. CePdAl orders below 0953-8984/8/50/043/img9 with an incommensurate antiferromagnetic propagation vector 0953-8984/8/50/043/img10, and a longitudinal sine-wave (LSW) modulated spin arrangement. Magnetically ordered moments at Ce(1) and Ce(3) coexist with frustrated disordered moments at Ce(2). The experimentally determined magnetic structure is in agreement with group theoretical symmetry analysis considerations, calculated by the program MODY, which confirm that for Ce(2) an ordered magnetic moment parallel to the magnetically easy c-axis is forbidden by symmetry. Further low-temperature experiments give evidence for a second magnetic phase transition in CePdAl between 0.6 and 1.3 K. Magnetic structures of CePdAl are compared with those of the isostructural compound TbNiAl, where a non-zero ordered magnetic moment for the geometrically frustrated Tb(2) atoms is allowed by symmetry.
Study on using I - as heavy atom perturber in cyclodextrin-induced room temperature phosphorimetry

NASA Astrophysics Data System (ADS)

Li, Longdi; Hai, Xuan; Tong, Aijun

2000-07-01

A cyclodextrin induced room temperature phosphorimetry (CD-RTP) for determine β-NOA, which using I- as a heavy atom perturber (HAP) and sodium sulfite as a deoxygenator, was developed. The phosphorescence peak wavelength maxima λex/λem=287/496 521 nm. The analytical curve of β-NOA gives a linear dynamic range of 2.0×10-7-6.0×10-6 mol/l and a detection limit of 4×10-8 mol/l. The relative standard deviation (RSD; n=7) was 3.2% for the 4.0×10-6 mol/l β-NOA in spiked apple samples. The influence of I- concentration on RTP lifetime of β-NOA was studied in detail, the static Stern-Volmer equation for phosphorescence was derived and the luminescence kinetic parameters were calculated. It is found that the relation between I- concentration (x) and RTP lifetime (τ) can be expressed as τ=1.047 e-0.354x and the rate constants of phosphorescence emission kp and non-radiation process ki from T1→S0 were 0.9551s-1 and 0.4276 s-1l-1mol, respectively.
Atom-scale depth localization of biologically important chemical elements in molecular layers

PubMed Central

Schneck, Emanuel; Scoppola, Ernesto; Drnec, Jakub; Mocuta, Cristian; Felici, Roberto; Novikov, Dmitri; Fragneto, Giovanna; Daillant, Jean

2016-01-01

In nature, biomolecules are often organized as functional thin layers in interfacial architectures, the most prominent examples being biological membranes. Biomolecular layers play also important roles in context with biotechnological surfaces, for instance, when they are the result of adsorption processes. For the understanding of many biological or biotechnologically relevant phenomena, detailed structural insight into the involved biomolecular layers is required. Here, we use standing-wave X-ray fluorescence (SWXF) to localize chemical elements in solid-supported lipid and protein layers with near-Ångstrom precision. The technique complements traditional specular reflectometry experiments that merely yield the layers’ global density profiles. While earlier work mostly focused on relatively heavy elements, typically metal ions, we show that it is also possible to determine the position of the comparatively light elements S and P, which are found in the most abundant classes of biomolecules and are therefore particularly important. With that, we overcome the need of artificial heavy atom labels, the main obstacle to a broader application of high-resolution SWXF in the fields of biology and soft matter. This work may thus constitute the basis for the label-free, element-specific structural investigation of complex biomolecular layers and biological surfaces. PMID:27503887
4-(2-Pyridylazo)-resorcinol Functionalized Thermosensitive Ionic Microgels for Optical Detection of Heavy Metal Ions at Nanomolar Level.

PubMed

Zhou, Xianjing; Nie, Jingjing; Du, Binyang

2015-10-07

4-(2-Pyridylazo)-resorcinol (PAR) functionalized thermosensitive ionic microgels (PAR-MG) were synthesized by a one-pot quaternization method. The PAR-MG microgels were spherical in shape with radius of ca. 166.0 nm and narrow size distribution and exhibited thermo-sensitivity in aqueous solution. The PAR-MG microgels could optically detect trace heavy metal ions, such as Cu(2+), Mn(2+), Pb(2+), Zn(2+), and Ni(2+), in aqueous solutions with high selectivity and sensitivity. The PAR-MG microgel suspensions exhibited characteristic color with the presence of various trace heavy metal ions, which could be visually distinguished by naked eyes. The limit of colorimetric detection (DL) was determined to be 38 nM for Cu(2+) at pH 3, 12 nM for Cu(2+) at pH 7, and 14, 79, 20, and 21 nM for Mn(2+), Pb(2+), Zn(2+), and Ni(2+), respectively, at pH 11, which was lower than (or close to) the United States Environmental Protection Agency standard for the safety limit of these heavy metal ions in drinking water. The mechanism of detection was attributed to the chelation between the nitrogen atoms and o-hydroxyl groups of PAR within the microgels and heavy metal ions.
Quality of Kelantan drinking water and knowledge, attitude and practice among the population of Pasir Mas, Malaysia.

PubMed

Ab Razak, N H; Praveena, S M; Aris, A Z; Hashim, Z

2016-02-01

Information about the quality of drinking water, together with analysis of knowledge, attitude and practice (KAP) analysis and health risk assessment (HRA) remain limited. The aims of this study were: (1) to ascertain the level of KAP regarding heavy metal contamination of drinking water in Pasir Mas; (2) to determine the concentration of heavy metals (Al, Cr, Cu, Fe, Ni, Pb, Zn and Cd) in drinking water in Pasir Mas; and (3) to estimate the health risks (non-carcinogenic and carcinogenic) caused by heavy metal exposure through drinking water using hazard quotient and lifetime cancer risk. Information on KAP was collected using a standardized questionnaire. Heavy metal analysis of drinking water samples was performed using graphite furnace atomic absorption spectrophotometry. The population of Pasir Mas has good knowledge (80%), a less positive attitude (93%) and good practice (81%) towards heavy metal contamination of drinking water. The concentrations of heavy metals analysed in this study were found to be below the permissible limits for drinking water set by the Malaysian Ministry of Health and the World Health Organization. The HRA showed no potential non-carcinogenic and carcinogenic risks from the intake of heavy metal through drinking water. By investigating the quality of drinking water, KAP and HRA, the results of this study will provide authorities with the knowledge and resources to improve the management of drinking water quality in the future. Copyright © 2015 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.
Heavy element effects in the diagonal Born–Oppenheimer correction within a relativistic spin-free Hamiltonian

DOE PAGES

Imafuku, Yuji; Abe, Minori; Schmidt, Michael W.; ...

2016-03-22

Methodologies beyond the Born–Oppenheimer (BO) approximation are nowadays important to explain high precision spectroscopic measurements. Most previous evaluations of the BO correction are, however, focused on light-element molecules and based on a nonrelativistic Hamiltonian, so no information about the BO approximation (BOA) breakdown in heavy-element molecules is available. The present work is the first to investigate the BOA breakdown for the entire periodic table, by considering scalar relativistic effects in the Diagonal BO correction (DBOC). In closed shell atoms, the relativistic EDBOC scales as Z 1.25 and the nonrelativistic EDBOC scales as Z 1.17, where Z is the atomic number.more » Hence, we found that EDBOC becomes larger in heavy element atoms and molecules, and the relativistic EDBOC increases faster than nonrelativistic EDBOC. We have further investigated the DBOC effects on properties such as potential energy curves, spectroscopic parameters, and various energetic properties. The DBOC effects for these properties are mostly affected by the lightest atom in the molecule. Furthermore, in X 2 or XAt molecule (X = H, Li, Na, K, Rb, and Cs) the effect of DBOC systematically decreases when X becomes heavier but in HX molecules, the effect of DBOC seems relatively similar among all the molecules.« less
Density functional investigation of mercury and arsenic adsorption on nitrogen doped graphene decorated with palladium clusters: A promising heavy metal sensing material in farmland

NASA Astrophysics Data System (ADS)

Zhao, Chunjiang; Wu, Huarui

2017-03-01

Density functional theory calculations are carried out to study the adsorption of mercury and arsenic on Pdn (n = 1-6) supported on pyridine-like nitrogen doped graphene (PNG). Owing to the promising sensitivity in trace amounts of atoms or molecules, PNG can be acted as micro-sensor for sensing heavy metals in agriculture soils. Through the analyses of structural and electronic properties of pristine PNG and Pd atom decorated PNG, we find that the most favorable adsorption site for Pd atom is the vacancy site. The analyses of structural and electronic properties reveal that the Pd atom or clusters can enhance the reactivity for Hg and AsH3 adsorption on PNG. The adsorption ability of Hg on Pdn decorated PNG is found to be related to the d-band center (εd) of the Pdn, in which the closer εd of Pdn to the Fermi level, the higher adsorption strength for Hg on Pdn decorated PNG. Moreover, the charge transfer between Pdn and arsenic may constitute arsenic adsorption on Pdn decorated PNG. Further design of highly efficient carbon based sorbents for heavy metals removal should be focused on tailoring εd of adsorbed metals.
Bremsstrahlung-Based Imaging and Assays of Radioactive, Mixed and Hazardous Waste

NASA Astrophysics Data System (ADS)

Kwofie, J.; Wells, D. P.; Selim, F. A.; Harmon, F.; Duttagupta, S. P.; Jones, J. L.; White, T.; Roney, T.

2003-08-01

A new nondestructive accelerator based x-ray fluorescence (AXRF) approach has been developed to identify heavy metals in large-volume samples. Such samples are an important part of the process and waste streams of U.S Department of Energy sites, as well as other industries such as mining and milling. Distributions of heavy metal impurities in these process and waste samples can range from homogeneous to highly inhomogeneous, and non-destructive assays and imaging that can address both are urgently needed. Our approach is based on using high-energy, pulsed bremsstrahlung beams (3-6.5 MeV) from small electron accelerators to produce K-shell atomic fluorescence x-rays. In addition we exploit pair-production, Compton scattering and x-ray transmission measurements from these beams to probe locations of high density and high atomic number. The excellent penetrability of these beams allows assays and images for soil-like samples at least 15 g/cm2 thick, with elemental impurities of atomic number greater than approximately 50. Fluorescence yield of a variety of targets was measured as a function of impurity atomic number, impurity homogeneity, and sample thickness. We report on actual and potential detection limits of heavy metal impurities in a soil matrix for a variety of samples, and on the potential for imaging, using AXRF and these related probes.
Phosphorescence Tuning through Heavy Atom Placement in Unsymmetrical Difluoroboron β-Diketonate Materials.

PubMed

Liu, Tiandong; Zhang, Guoqing; Evans, Ruffin E; Trindle, Carl O; Altun, Zikri; DeRosa, Christopher A; Wang, Fang; Zhuang, Meng; Fraser, Cassandra L

2018-02-06

Difluoroboron β-diketonates (BF 2 bdks) show both fluorescence (F) and room-temperature phosphorescence (RTP) when confined to a rigid matrix, such as poly(lactic acid). These materials have been utilized as optical oxygen sensors (e.g., in tumors, wounds, and cells). Spectral features include charge transfer (CT) from the major aromatic donor to the dioxaborine acceptor. A series of naphthyl-phenyl dyes (BF 2 nbm) (1-6) were prepared to test heavy-atom placement effects. The BF 2 nbm dye (1) was substituted with Br on naphthyl (2), phenyl (3), or both rings (4) to tailor the fluorescence/phosphorescence ratio and RTP lifetime-important features for designing O 2 sensing dyes by means of the heavy atom effect. Computational studies identify the naphthyl ring as the major donor. Thus, Br substitution on the naphthyl ring produced greater effects on the optical properties, such as increased RTP intensity and decreased RTP lifetime compared to phenyl substitution. However, for electron-donating piperidyl-phenyl dyes (5), the phenyl aromatic is the major donor. As a result, Br substitution on the naphthyl ring (6) did not alter the optical properties significantly. Experimental data and computational modeling show the importance of Br position. The S 1 and T 1 states are described by two singly occupied MOs (SOMOs). When both of these SOMOs have substantial amplitude on the heavy atom, passage from S 1 to T 1 and emission from T 1 to S 0 are both favored. This shortens the excited-state lifetimes and enhances phosphorescence. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
The role of electronic mechanisms in surface erosion and glow phenomena

NASA Technical Reports Server (NTRS)

Haglund, Richard F., Jr.

1987-01-01

Experimental studies of desorption induced by electronic transitions (DIET) are described. Such studies are producing an increasingly complete picture of the dynamical pathways through which incident electronic energy is absorbed and rechanneled to produce macroscopic erosion and glow. These mechanistic studies can determine rate constants for erosion and glow processes in model materials and provide valuable guidance in materials selection and development. Extensive experiments with electron, photon, and heavy particle irradiation of alkali halides and other simple model materials have produced evidence showing that: (1) surface erosion, consisting primarily in the ejection or desorption of ground-state neutral atoms, occurs with large efficiencies for all irradiated species; (2) surface glow, resulting from the radiative decay of desorbed atoms, likewise occurs for all irradiating species; (3) the typical mechanism for ground-state neutral desorption is exciton formation, followed by relaxation to a permanent, mobile electronic defect which is the precursor to bond-breaking in the surface or near-surface bulk of the material; and (4) the mechanisms for excited atom formation may include curve crossing in atomic collisions, interactions with surface defect or impurity states, or defect diffusion.
On the influence of crystal size and wavelength on native SAD phasing.

PubMed

Liebschner, Dorothee; Yamada, Yusuke; Matsugaki, Naohiro; Senda, Miki; Senda, Toshiya

2016-06-01

Native SAD is an emerging phasing technique that uses the anomalous signal of native heavy atoms to obtain crystallographic phases. The method does not require specific sample preparation to add anomalous scatterers, as the light atoms contained in the native sample are used as marker atoms. The most abundant anomalous scatterer used for native SAD, which is present in almost all proteins, is sulfur. However, the absorption edge of sulfur is at low energy (2.472 keV = 5.016 Å), which makes it challenging to carry out native SAD phasing experiments as most synchrotron beamlines are optimized for shorter wavelength ranges where the anomalous signal of sulfur is weak; for longer wavelengths, which produce larger anomalous differences, the absorption of X-rays by the sample, solvent, loop and surrounding medium (e.g. air) increases tremendously. Therefore, a compromise has to be found between measuring strong anomalous signal and minimizing absorption. It was thus hypothesized that shorter wavelengths should be used for large crystals and longer wavelengths for small crystals, but no thorough experimental analyses have been reported to date. To study the influence of crystal size and wavelength, native SAD experiments were carried out at different wavelengths (1.9 and 2.7 Å with a helium cone; 3.0 and 3.3 Å with a helium chamber) using lysozyme and ferredoxin reductase crystals of various sizes. For the tested crystals, the results suggest that larger sample sizes do not have a detrimental effect on native SAD data and that long wavelengths give a clear advantage with small samples compared with short wavelengths. The resolution dependency of substructure determination was analyzed and showed that high-symmetry crystals with small unit cells require higher resolution for the successful placement of heavy atoms.
Physical conditions and chemical processes during single-bubble sonoluminescence

NASA Astrophysics Data System (ADS)

Flannigan, David J.

In order to gain insight into the physical conditions and chemical processes associated with single-bubble sonoluminescence (SBSL), nonvolatile liquids such as concentrated sulfuric acid (H2SO 4) were explored. The SBSL radiant powers from H2SO 4 aqueous solutions were found to be over 103 times larger than those typically observed for SBSL from water. In addition, the emission spectra contain extensive bands and lines from molecules, atoms, and ions. The population of high-energy states of atoms (20 eV) and ions (37 eV) provides definitive experimental evidence of the formation of a plasma. By using various techniques (e.g., small molecules and atoms as intra-cavity probes, standard methods of plasma diagnostics, and spectrometric methods of pyrometry), it was possible to quantify the heavy particle temperatures (15,000 K), heavy particle densities (1021 cm-3) and pressures (4,000 bar), and plasma electron densities (1018 cm -3) generated during SBSL from H2SO4. It was also found that SBSL from H2SO4 containing mixtures of noble gas and air was quenched up to a critical acoustic pressure, above which the radiant powers increased by 104. From the spectral profiles it was determined that the air limited heating and plasma formation by endothermic chemical reactions and energy-transfer reactions. Simultaneous stroboscopic and spectroscopic studies of SBSL in H2SO4 containing alkali-metal sulfates showed that dramatic changes in the bubble dynamics correlated with the onset of emission from nonvolatile species such as Na and K atoms. These effects were attributed to the development of interfacial instabilities with increasing translational velocity of the bubble.
Correlation and transport properties for mixtures at constant pressure and temperature

NASA Astrophysics Data System (ADS)

White, Alexander J.; Collins, Lee A.; Kress, Joel D.; Ticknor, Christopher; Clérouin, Jean; Arnault, Philippe; Desbiens, Nicolas

2017-06-01

Transport properties of mixtures of elements in the dense plasma regime play an important role in natural astrophysical and experimental systems, e.g., inertial confinement fusion. We present a series of orbital-free molecular dynamics simulations on dense plasma mixtures with comparison to a global pseudo ion in jellium model. Hydrogen is mixed with elements of increasingly high atomic number (lithium, carbon, aluminum, copper, and silver) at a fixed temperature of 100 eV and constant pressure set by pure hydrogen at 2 g/cm 3 , namely, 370 Mbars. We compute ionic transport coefficients, such as self-diffusion, mutual diffusion, and viscosity for various concentrations. Small concentrations of the heavy atoms significantly change the density of the plasma and decrease the transport coefficients. The structure of the mixture evidences a strong Coulomb coupling between heavy ions and the appearance of a broad correlation peak at short distances between hydrogen atoms. The concept of an effective one component plasma is used to quantify the overcorrelation of the light element induced by the admixture of a heavy element.
Correlation and transport properties for mixtures at constant pressure and temperature

DOE PAGES

White, Alexander J.; Collins, Lee A.; Kress, Joel D.; ...

2017-06-02

Transport properties of mixtures of elements in the dense plasma regime play an important role in natural astrophysical and experimental systems, e.g., inertial confinement fusion. In this paper, we present a series of orbital-free molecular dynamics simulations on dense plasma mixtures with comparison to a global pseudo ion in jellium model. Hydrogen is mixed with elements of increasingly high atomic number (lithium, carbon, aluminum, copper, and silver) at a fixed temperature of 100 eV and constant pressure set by pure hydrogen at 2g/cm 3, namely, 370 Mbars. We compute ionic transport coefficients, such as self-diffusion, mutual diffusion, and viscosity formore » various concentrations. Small concentrations of the heavy atoms significantly change the density of the plasma and decrease the transport coefficients. The structure of the mixture evidences a strong Coulomb coupling between heavy ions and the appearance of a broad correlation peak at short distances between hydrogen atoms. Finally, the concept of an effective one component plasma is used to quantify the overcorrelation of the light element induced by the admixture of a heavy element.« less
Correlation and transport properties for mixtures at constant pressure and temperature

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

White, Alexander J.; Collins, Lee A.; Kress, Joel D.

Transport properties of mixtures of elements in the dense plasma regime play an important role in natural astrophysical and experimental systems, e.g., inertial confinement fusion. In this paper, we present a series of orbital-free molecular dynamics simulations on dense plasma mixtures with comparison to a global pseudo ion in jellium model. Hydrogen is mixed with elements of increasingly high atomic number (lithium, carbon, aluminum, copper, and silver) at a fixed temperature of 100 eV and constant pressure set by pure hydrogen at 2g/cm 3, namely, 370 Mbars. We compute ionic transport coefficients, such as self-diffusion, mutual diffusion, and viscosity formore » various concentrations. Small concentrations of the heavy atoms significantly change the density of the plasma and decrease the transport coefficients. The structure of the mixture evidences a strong Coulomb coupling between heavy ions and the appearance of a broad correlation peak at short distances between hydrogen atoms. Finally, the concept of an effective one component plasma is used to quantify the overcorrelation of the light element induced by the admixture of a heavy element.« less
Fast Heavy-Atom Tunneling in Trifluoroacetyl Nitrene.

PubMed

Wu, Zhuang; Feng, Ruijuan; Li, Hongmin; Xu, Jian; Deng, Guohai; Abe, Manabu; Bégué, Didier; Liu, Kun; Zeng, Xiaoqing

2017-12-04

Chemical reactions involving quantum mechanical tunneling (QMT) increasingly attract the attention of scientists. In contrast to the hydrogen-tunneling as frequently observed in chemistry and biology, tunneling solely by heavy atoms is rare. Herein, we report heavy-atom tunneling in trifluoroacetyl nitrene, CF 3 C(O)N. The carbonyl nitrene CF 3 C(O)N in the triplet ground state was generated in cryogenic matrices by laser (193 or 266 nm) photolysis of CF 3 C(O)N 3 and characterized by IR and EPR spectroscopy. In contrast to the theoretically predicted activation barriers (>10 kcal mol -1 ), CF 3 C(O)N undergoes rapid rearrangement into CF 3 NCO with half-life times of less than 10 min and unprecedentedly large 14 N/ 15 N kinetic isotope effects (1.18-1.33) in solid Ar, Ne, and N 2 matrices even at 2.8 K. The tunneling disappearance of CF 3 C(O)N becomes much slower in the chemically active toluene and in 2-methyltetrahydrofuran at 5 K. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
COMBUSTION OF HEAVY LIQUID FUELS

DTIC Science & Technology

characteristics of individual fuel droplets, as functions of the external conditions and fuel properties, the droplet combustion process in a flame ... length and the quality of atomization are examined. In addition, atomization quality is covered, and nozzle systems and the construction of nozzles are
Heavy metals in liquid pig manure in light of bacterial antimicrobial resistance

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

Hoelzel, Christina S., E-mail: Christina.Hoelzel@wzw.tum.de; Mueller, Christa; Harms, Katrin S.

Heavy metals are regularly found in liquid pig manure, and might interact with bacterial antimicrobial resistance. Concentrations of heavy metals were determined by atomic spectroscopic methods in 305 pig manure samples and were connected to the phenotypic resistance of Escherichia coli (n=613) against 29 antimicrobial drugs. Concentrations of heavy metals (/kg dry matter) were 0.08-5.30 mg cadmium, 1.1-32.0 mg chrome, 22.4-3387.6 mg copper, <2.0-26.7 mg lead, <0.01-0.11 mg mercury, 3.1-97.3 mg nickel and 93.0-8239.0 mg zinc. Associated with the detection of copper and zinc, resistance rates against {beta}-lactams were significantly elevated. By contrast, the presence of mercury was significantly associatedmore » with low antimicrobial resistance rates of Escherichia coli against {beta}-lactams, aminoglycosides and other antibiotics. Effects of subinhibitory concentrations of mercury on bacterial resistance against penicillins, cephalosporins, aminoglycosides and doxycycline were also demonstrated in a laboratory trial. Antimicrobial resistance in the porcine microflora might be increased by copper and zinc. By contrast, the occurrence of mercury in the environment might, due to co-toxicity, act counter-selective against antimicrobial resistant strains.« less

Phytoremediation of heavy metal copper (Cu2+) by sunflower (Helianthus annuus l.)

NASA Astrophysics Data System (ADS)

Mahardika, G.; Rinanti, A.; Fachrul, M. F.

2018-01-01

A study in microcosmic condition has been carried out to determine the effectiveness of Helianthus annuus as a hyperaccumulator plant for heavy metal, Copper (Cu2+), that exposed in the soil. Artificial pollutants containing Copper (Cu2+) 0, 60, 120, 180 ppm are exposed to uncontaminated soil. The 12-weeks old H. annuus seedling were grown in Cu2+ contaminated soil, with variations of absorption time 3, 6, and 9 weeks. Analysis of Cu2+ concentration on soil and H. annuus (root, stem, leaf) was analised by Atomic Absorbtion Spectrometry (AAS). H. annuus are capable for Cu2+ removal, and the highest removal of Cu2+ is 85.56%, the highest metal accumulation/bioconcentration factor (BCF) is 0.99 occurred at roots with 9 weeks of exposure time and the highest translocation factor (TF) is 0.71. This highest removal is five times better than absorption by stems and leaves. The results concluded, the use of H. annuus for phytoextraction of heavy metals Cu2+ in contaminated soil can be an alternative to the absorption of heavy metal Cu2+ with low concentration metals which is generally very difficult to do in physical-chemical removal.
RADIATION DOSE DUE TO RADON AND HEAVY METAL ANALYSIS IN DRINKING WATER SAMPLES OF JAMMU DISTRICT, JAMMU & KASHMIR, INDIA.

PubMed

Kumar, A; Kaur, M; Sharma, S; Mehra, R; Sharma, D K; Mishra, R

2016-10-01

In the present investigation, radon concentration and heavy metal analysis were carried out in drinking water samples in Jammu district, Jammu & Kashmir, India. The radon concentration was measured by using RAD-7, portable alpha particle detector. The values of radon concentration in drinking water samples were also compared within the safe limit recommended by different health agencies. The total annual effective dose ranged from 53.04 to 197.29 µSv y -1 The annual effective dose from few locations from the studied area was found to be greater than the safe limit (100 µSv y -1 ) suggested by World Health Organisation (WHO) and EU Council. Heavy metal concentration was determined by atomic absorption spectrophotometer. A total of eight elements were analysed, viz. arsenic, mercury, zinc, iron, copper, chromium, manganese and cadmium. Heavy metals are considered to be the major pollutants of water sources. The results were compared with the limits of WHO, EU and Indian organisations. The trace metal analysis is not on the exceeding side of the permissible limit in all the samples. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
Pollution Problem in River Kabul: Accumulation Estimates of Heavy Metals in Native Fish Species.

PubMed

Ahmad, Habib; Yousafzai, Ali Muhammad; Siraj, Muhammad; Ahmad, Rashid; Ahmad, Israr; Nadeem, Muhammad Shahid; Ahmad, Waqar; Akbar, Nazia; Muhammad, Khushi

2015-01-01

The contamination of aquatic systems with heavy metals is affecting the fish population and hence results in a decline of productivity rate. River Kabul is a transcountry river originating at Paghman province in Afghanistan and inters in Khyber Pakhtunkhwa province of Pakistan and it is the major source of irrigation and more than 54 fish species have been reported in the river. Present study aimed at the estimation of heavy metals load in the fish living in River Kabul. Heavy metals including chromium, nickel, copper, zinc, cadmium, and lead were determined through atomic absorption spectrophotometer after tissue digestion by adopting standard procedures. Concentrations of these metals were recorded in muscles and liver of five native fish species, namely, Wallago attu, Aorichthys seenghala, Cyprinus carpio, Labeo dyocheilus, and Ompok bimaculatus. The concentrations of chromium, nickel, copper, zinc, and lead were higher in both of the tissues, whereas the concentration of cadmium was comparatively low. However, the concentration of metals was exceeding the RDA (Recommended Dietary Allowance of USA) limits. Hence, continuous fish consumption may create health problems for the consumers. The results of the present study are alarming and suggest implementing environmental laws and initiation of a biomonitoring program of the river.
Atomic x-ray production by relativistic heavy ions. [Cross sections, K and L shells, ionization 3 and 4. 88 GEV holes

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

Ioannou, J.G.

1977-12-01

The interaction of heavy ion projectiles with the electrons of target atoms gives rise to the production, in the target, of K-, L- or higher shell vacancies which are in turn followed by the emission of characteristic x-rays. The calculation of the theoretical value of the K- and L-shells vacancy production cross section was carried out for heavy ion projectiles of any energy. The transverse component of the cross section is calculated for the first time in detail and extensive tables of its numerical value as a function of its parameters are also given. Experimental work for 4.88 GeV protonsmore » and 3 GeV carbon ions is described. The K vacancy cross section has been measured for a variety of targets from Ti to U. The agreement between the theoretical predictions and experimental results for the 4.88 GeV protons is rather satisfactory. For the 3 GeV carbon ions, however, it is observed that the deviation of the theoretical and experimental values of the K vacancy production becomes larger with the heavier target element. Consequently, the simple scaling law of Z/sub 1//sup 2/ for the cross section of the heavy ion with atomic number Z/sub 1/ to the proton cross section is not true, for the K-shell at least. A dependence on the atomic number Z/sub 2/ of the target of the form (Z/sub 1/ - ..cap alpha..Z/sub 2/)/sup 2/, instead of Z/sub 1//sup 2/, is found to give extremely good agreement between theory and experiment. Although the exact physical meaning of such dependence is not yet clearly understood, it is believed to be indicative of some sort of screening effect of the incoming fast projectile by the fast moving in Bohr orbits K-shell electrons of the target. The enhancement of the K-shell ionization cross section by relativistic heavy ions on heavy targets is also discussed in terms of its practical applications in various branches of science and technology.« less
Relativistic Collisions of Highly-Charged Ions

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

Ionescu, Dorin; Belkacem, Ali

1998-11-19

The physics of elementary atomic processes in relativistic collisions between highly-charged ions and atoms or other ions is briefly discussed, and some recent theoretical and experimental results in this field are summarized. They include excitation, capture, ionization, and electron-positron pair creation. The numerical solution of the two-center Dirac equation in momentum space is shown to be a powerful nonperturbative method for describing atomic processes in relativistic collisions involving heavy and highly-charged ions. By propagating negative-energy wave packets in time the evolution of the QED vacuum around heavy ions in relativistic motion is investigated. Recent results obtained from numerical calculations usingmore » massively parallel processing on the Cray-T3E supercomputer of the National Energy Research Scientific Computer Center (NERSC) at Berkeley National Laboratory are presented.« less
Experimental investigation of the physical properties of medium and heavy oils, their vaporization and use in explosion engines. Part IV

NASA Technical Reports Server (NTRS)

Heinlein, Fritz

1926-01-01

This report presents a theoretical treatment of the vaporization process of medium and heavy oils. The results of this investigation, which were mostly obtained from the lighter components of the heavy fuels, require a 10- or 16-fold vaporization in comparison with gasoline. We must attain a still finer degree of atomization, in order to include the heavier components.
Designing Superhard Materials by Incorporating Boron Into Heavy Transition Metals

NASA Astrophysics Data System (ADS)

Liang, Yongcheng; Li, Anhu; Zhao, Jianzhi; Zhang, Wenqing

First-principles calculations on the incompressibility, elasticity and hardness of the Os, OsB2, Re, and ReB2 materials have systematically been performed by the plane-wave basis pseudopotential method. Transition metals Os and Re, which have high bulk modulus but low hardness, can be converted into hard materials by combining them with small B atoms. Moreover, electronic and structural mechanisms of ReB2 and OsB2 are analyzed in detail and compared. It is shown that incorporating small B atoms into heavy transition metals should be a valid pathway to obtain new superhard materials.
O-shell emission of heavy atoms in an optically thin tokamak plasma

NASA Astrophysics Data System (ADS)

Finkenthal, M.; Lippmann, S.; Huang, L. K.; Zwicker, A.; Moos, H. W.; Goldstein, W. H.; Osterheld, A. L.

1992-04-01

Heavy atoms Au (Z=79), Pb (Z=82), Bi (Z=83), and U (Z=92) have been introduced in the low-density (ne~1013 cm-3) high-temperature (Te>=1 keV) TEXT tokamak (Fusion Research Center, University of Texas at Austin) plasma. The emission has been measured in the 50-200-Å range using a photometrically calibrated, time-resolving grazing-incidence spectrometer. The O-shell ion emission has been identified by comparison with ab initio energy-level calculations and line-intensity predictions of collisional radiative models for various charge states with 5p65dk ground-state configurations.
Secondary Interstellar Oxygen in the Heliosphere: Numerical Modeling and Comparison with IBEX-Lo Data

NASA Astrophysics Data System (ADS)

Baliukin, I. I.; Izmodenov, V. V.; Möbius, E.; Alexashov, D. B.; Katushkina, O. A.; Kucharek, H.

2017-12-01

Quantitative analysis of the interstellar heavy (oxygen and neon) atom fluxes obtained by the Interstellar Boundary Explorer (IBEX) suggests the existence of the secondary interstellar oxygen component. This component is formed near the heliopause due to charge exchange of interstellar oxygen ions with hydrogen atoms, as was predicted theoretically. A detailed quantitative analysis of the fluxes of interstellar heavy atoms is only possible with a model that takes into account both the filtration of primary and the production of secondary interstellar oxygen in the boundary region of the heliosphere as well as a detailed simulation of the motion of interstellar atoms inside the heliosphere. This simulation must take into account photoionization, charge exchange with the protons of the solar wind and solar gravitational attraction. This paper presents the results of modeling interstellar oxygen and neon atoms through the heliospheric interface and inside the heliosphere based on a three-dimensional kinetic-MHD model of the solar wind interaction with the local interstellar medium and a comparison of these results with the data obtained on the IBEX spacecraft.
The Difference a Single Atom Can Make: Synthesis and Design at the Chemistry–Biology Interface

PubMed Central

2017-01-01

A Perspective of work in our laboratory on the examination of biologically active compounds, especially natural products, is presented. In the context of individual programs and along with a summary of our work, selected cases are presented that illustrate the impact single atom changes can have on the biological properties of the compounds. The examples were chosen to highlight single heavy atom changes that improve activity, rather than those that involve informative alterations that reduce or abolish activity. The examples were also chosen to illustrate that the impact of such single-atom changes can originate from steric, electronic, conformational, or H-bonding effects, from changes in functional reactivity, from fundamental intermolecular interactions with a biological target, from introduction of a new or altered functionalization site, or from features as simple as improvements in stability or physical properties. Nearly all the examples highlighted represent not only unusual instances of productive deep-seated natural product modifications and were introduced through total synthesis but are also remarkable in that they are derived from only a single heavy atom change in the structure. PMID:28945374
The effects of point pollutants-originated heavy metals (lead, copper, iron, and cadmium) on fish living in Yeşilırmak River, Turkey.

PubMed

Polat, Fatih; Akın, Şenol; Yıldırım, Alper; Dal, Tarık

2016-08-01

In this study, the association between heavy metals in water and cyprinids sampled from the Yeşilırmak River stretch, which is frequently exposed to pollutant sources (a sugar production factory (Turhal) and solid wastes dump area (Taşlıçiftlik) was explored, and the oxidative effects of heavy metals on cyprinids were evaluated through analyzing some liver enzymes, namely, superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), and cortisol. The heavy metal concentrations of both fish and water, collected from three different locations along the river during the summer of 2011 and winter of 2010 (Turhal, Taşlıçiftlik, and Gümenek), were determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES). The water and fish liver heavy metal concentrations exhibited increasing trends from upstream (Gümenek) to downstream (Turhal). The water and liver samples collected during the summer had higher heavy metal concentrations than those obtained during the winter. The mean heavy metal concentrations increased from Gümenek to Turhal. The liver heavy metal concentrations were higher than those in the water and exhibited almost the same increasing trend from Gümenek to Turhal. Positive relationships between liver and water heavy metal concentrations, especially for cadmium (R 2 = 0.91) and lead (R 2 = 0.98), were obtained. Among the liver enzymes, only MDA followed the same increasing trend from Gümenek to Turhal as was obtained for heavy metals. On the other hand, CAT and SOD had a contrary spatial pattern of change to those of heavy metals and MDA. Although the values of heavy metals and MDA in Taşlıçiftlik were between the two other locations, fish inhabiting this locality had significantly higher values of cortisol, which is an indication of the other stress-causing factors for fish. © The Author(s) 2015.
Atomic contributions from spin-orbit coupling to 29Si NMR chemical shifts in metallasilatrane complexes.

PubMed

Autschbach, Jochen; Sutter, Kiplangat; Truflandier, Lionel A; Brendler, Erica; Wagler, Jörg

2012-10-01

New members of a novel class of metallasilatrane complexes [X-Si-(μ-mt)(4)-M-Y], with M=Ni, Pd, Pt, X=F, Cl, Y=Cl, Br, I, and mt=2-mercapto-1-methylimidazolide, have been synthesized and characterized structurally by X-ray diffraction and by (29)Si solid-state NMR. Spin-orbit (SO) effects on the (29)Si chemical shifts induced by the metal, by the sulfur atoms in the ligand, and by heavy halide ligands Y=Cl, Br, I were investigated with the help of relativistic density functional calculations. Operators used in the calculations were constructed such that SO coupling can selectively be switched off for certain atoms. The unexpectedly large SO effects on the (29)Si shielding in the Ni complex with X=Y=Cl reported recently originate directly from the Ni atom, not from other moderately heavy atoms in the complex. With respect to Pd, SO effects are amplified for Ni owing to its smaller ligand-field splitting, despite the smaller nuclear charge. In the X=Cl, Y=Cl, Br, I series of complexes the Y ligand strongly modulates the (29)Si shift by amplifying or suppressing the metal SO effects. The pronounced delocalization of the partially covalent M←Y bond plays an important role in modulating the (29)Si shielding. We also demonstrate an influence from the X ligand on the (29)Si SO shielding contributions originating at Y. The NMR spectra for [X-Si-(μ-mt)(4)-M-Y] must be interpreted mainly based on electronic and relativistic effects, rather than structural differences between the complexes. The results highlight the sometimes unintuitive role of SO coupling in NMR spectra of complexes containing heavy atoms. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Assessment of heavy metal pollution in Córdoba (Spain) by biomonitoring foraging honeybee.

PubMed

Gutiérrez, Miriam; Molero, Rafael; Gaju, Miquel; van der Steen, Josef; Porrini, Claudio; Ruiz, José Antonio

2015-10-01

Due to features that make them outstanding environmental bioindicator, colonies of Apis mellifera are being used to study environmental pollution. The primary objective of this research was to use honeybee colonies to identify heavy metals and determine their utility for environmental management. Five stations each with two A. mellifera hives were strategically located in urban, industrial, agricultural and forested areas within the municipality of Córdoba (Spain), and foraging bees were collected from April to December in 2007, 2009 and 2010 to analyse spatial and temporal variation in Pb, Cr, Ni and Cd pollution. Metal concentrations, in milligram per kilogram of honeybee, were determined by inductively coupled plasma-atomic emission spectrometry and graphite furnace atomic absorption spectrophotometry. Significant differences in concentrations were found among the various locations and periods. The highest number of values exceeding the upper reference thresholds proposed for this study (Pb, 0.7 mg/kg; Cr, 0.12 mg/kg; Ni, 0.3 mg/kg; and Cd, 0.1 mg/kg) was observed for Pb and Cr (6.25% respectively), station S4 (13.22%), year 2007 (20.83%) and in months of May and July (11.90% each). Regarding the Cd, which was analysed only in 2010, the highest number of values exceeding the upper reference thresholds was 40%. Biomonitoring with colonies of A. mellifera could contribute to improved surveillance and control systems for atmospheric pollution by integrating qualitative and quantitative assessments, thus facilitating prevention and readiness in the event of environmental crises.
Heavy ligand atom induced large magnetic anisotropy in Mn(ii) complexes.

PubMed

Chowdhury, Sabyasachi Roy; Mishra, Sabyashachi

2017-06-28

In the search for single molecule magnets, metal ions are considered pivotal towards achieving large magnetic anisotropy barriers. In this context, the influence of ligands with heavy elements, showing large spin-orbit coupling, on magnetic anisotropy barriers was investigated using a series of Mn(ii)-based complexes, in which the metal ion did not have any orbital contribution. The mixing of metal and ligand orbitals was achieved by explicitly correlating the metal and ligand valence electrons with CASSCF calculations. The CASSCF wave functions were further used for evaluating spin-orbit coupling and zero-field splitting parameters for these complexes. For Mn(ii) complexes with heavy ligand atoms, such as Br and I, several interesting inter-state mixings occur via the spin-orbit operator, which results in large magnetic anisotropy in these Mn(ii) complexes.
Heavy Metals Bioaccumulation in Tissues of Spiny-Cheek Crayfish (Orconectes limosus) from Lake Gopło: Effect of Age and Sex.

PubMed

Stanek, Magdalena; Dąbrowski, Janusz; Różański, Szymon; Janicki, Bogdan; Długosz, Jacek

2017-06-01

The aim of the present work was to assess the concentrations of metals in the abdominal muscle and exoskeleton of 3-year-old males and 4-year-old females and males of spiny-cheek crayfish (Orconectes limosus) collected from Lake Gopło. A total of 93 males and 35 females were collected in autumn (October 2014). The analyzes of heavy metals were conducted by means of atomic absorption spectroscopy with a PU9100X spectrometer. The content of mercury was determined using AMA 254 mercury analyser. As analyses indicated heavy metals accumulated in the muscle and exoskeleton in the following sequence: Zn > Cu > Pb > Mn > Ni > Hg and Mn > Pb > Zn > Ni > Cu > Hg, respectively. Statistically significant differences between 3- and 4-year-old males were found for all analyzed metals. Gender dependent differences were calculated only for Ni in the muscle tissue and for Mn and Hg in the exoskeleton. In comparison with the study carried out 2 years ago notably higher concentrations of Pb were found in the muscle and a higher content of Zn, Pb, Mn and Ni was determined in the exoskeleton.
The role of gas in determining image quality and resolution during in situ scanning transmission electron microscopy experiments

DOE PAGES

Zhu, Yuanyuan; Browning, Nigel D.

2017-05-24

As gas-solid heterogeneous catalytic reactions are molecular in nature, a full mechanistic understanding of the process requires atomic scale characterization under realistic operating conditions. While atomic resolution imaging has become a routine in modern high-vacuum (scanning) transmission electron microscopy ((S)TEM), both image quality and resolution nominally degrade when reaction gases are introduced. In this work, we systematically assess the effects of different gases at various pressures on the quality and resolution of images obtained at room temperature in the annular dark field STEM imaging mode using a differentially pumped (DP) gas cell. This imaging mode is largely free from inelasticmore » scattering effects induced by the presence of gases and retains good imaging properties over a wide range of gas mass/pressures. Furthermore, we demonstrate the application of the ESTEM with atomic resolution images of a complex oxide alkane oxidation catalyst MoVNbTeOx (M1) immersed in light and heavy gas environments.« less
Oil residue contamination of continental shelf sediments of the Gulf of Mexico.

PubMed

Harding, V; Camp, J; Morgan, L J; Gryko, J

2016-12-15

We have investigated the distribution of a heavy oil residue in the coastal sediments of the Gulf of Mexico. The amount of the contamination was determined by high-temperature pyrolysis coupled with the Gas Chromatography-Mass Spectrometry (GCMS) of air-dried sediments. The pyrolysis products contain straight-chain saturated and unsaturated hydrocarbons, such as dodecane and 1-dodecene, resulting in a very characteristic pattern of double peaks in the GCMS. Hydrocarbons containing 8 to 23 carbon atoms were detected in the pyrolysis products. Using thermal pyrolysis we have found that the sediment samples collected along Texas, Louisiana, and Mississippi shores contain no detectable traces of oil residue, but most of the samples collected along Alabama and Florida shores contain ~200ppm of heavy oil residue. Copyright © 2016 Elsevier Ltd. All rights reserved.
The structure and energetics of the HCN → HNC transition state

NASA Astrophysics Data System (ADS)

Lee, Timothy J.; Rendell, Alistair P.

1991-03-01

The optimum geometries and quadratic force constants of HCN, HNC and the transition state connecting them have been determined at the single and double excitation coupled-cluster (CCSD) and CCSD(T) levels of theory. Energy differences were evaluated using the CCSD and CCSD(T) methods in conjunction with large atomic natural orbital basis sets containing g-type basis functions on the heavy atoms and f-type functions on hydrogen. The most reliable structure obtained for the transition state has bond distances of 1.194, 1.188 and 1.389 Å for rCN, rCH and rNH, respectively. Including a correction for zero-point vibrational energies, the transition state is predicted to be 44.6 ± 1.0 kcal/mol above the HCN isomer, while HNC is predicted to be 14.4 ± 1.0 kcal/mol above HCN. The latter value is in excellent agreement with the most recent experimental determination (14.8 ± 2.0 kcal/mol).
Physics Division annual review, 1 April 1975--31 March 1976. [ANL

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

Garvey, G. T.

1976-01-01

An overview is given of Physics Division activities in the following areas: the heavy-ion booster; medium-energy physics; heavy-ion physics; low-energy charged-particle physics; accelerator operations; neutron physics; theoretical nuclear physics, and atomic and molecular physics. A bibliography of publications amounts to 27 pages. (RWR)
Mass spectra of heavy ions near comet Halley

NASA Astrophysics Data System (ADS)

Korth, A.; Richter, A. K.; Loidl, A.; Anderson, K. A.; Carlson, C. W.; Curtis, D. W.; Lin, R. P.; Reme, H.; Sauvaud, J. A.; D'Uston, C.; Cotin, F.; Cros, A.; Mendis, D. A.

1986-05-01

The heavy-ion analyser aboard the Giotto spacecraft, detected the first cometary ions at a distance of ≡1.05x106km from the nucleus of comet Halley. In the inner coma the major ions identified are associated with the H2O, CO and CO2 groups. Ions of larger atomic mass unit are also present, corresponding possibly to various hydrocarbons, heavy metals of the iron-group or to sulphur compounds.

Mass spectra of heavy ions near comet Halley

NASA Technical Reports Server (NTRS)

Korth, A.; Richter, A. K.; Loidl, A.; Anderson, K. A.; Carlson, C. W.

1986-01-01

The heavy-ion analyzer, RPA2-PICCA, aboard the Giotto spacecraft, detected the first cometary ions at a distance of about 1.05 million km from the nucleus of comet Halley. In the inner coma the major ions identified are associated with the H2O, CO and CO2 groups. Ions of larger atomic mass unit are also present, corresponding possibly to various hydrocarbons, heavy metals of the iron-group or to sulphur compounds.
PINUS cembra L: histo-anatomical features, antioxidant enzyme activities and heavy metal contents of leaves and long shoots.

PubMed

Lungu, Cristina; Stănescu, Irina; Cojocaru, Sabina Ioana; Ciobanu, C; Ivănescu, Bianca; Miron, Anca

2015-01-01

This study aimed to investigate the histo-anatomical features of the long shoots and leaves (young and mature) of Pinus cembra L.. The activity of antioxidant enzymatic systems and the content of heavy metals were also evaluated. For the histo-anatomical study, the cross-sections were performed by usual techniques. The activity of antioxidant enzymatic systems (superoxide dismutase, catalase and peroxidase) was evaluated by spectrophotometric methods. The content of heavy metals was determined by atomic absorption spectroscopy. The cross-section through the long shoots shows many resiniferous canals and a periderm of variable thickness. The leaf has a triangular shape and only two vascular bundles in the inferior and upper levels. The highest level of superoxide dismutase activity (344.90 U/mg protein) was determined in the long shoots collected from a cembran pine in Vatra Dornei, while the highest level of peroxidase activity (7611.11 U/mg protein) was found in the leaves collected in Calimani Mountains. Cd level in all samples was under the quantification limit. Higher levels of Pb were determined in the long shoots (3 μg/g dry weight for the vegetal material collected in Vatra Dornei and 2.86 μg/g dry weight for the vegetal material collected in Calimani Mountains). Pinus cembra L. leaves show specific elements of subgenus Strobus (a triangular shape of the cross section, one single vascular bundle and two resiniferous canals). The results obtained for the superoxide dismutase and peroxidase activities corroborated with those obtained for the heavy metal contents indicate that antioxidant enzymes play an important role in the protection of Pinus cembra L. against exogenous stress factors.
Watershed-scale assessment of background concentrations and guidance values for heavy metals in soils from a semiarid and coastal zone of Brazil.

PubMed

da Silva, Yuri Jacques Agra Bezerra; do Nascimento, Clístenes Williams Araújo; Cantalice, José Ramon Barros; da Silva, Ygor Jacques Agra Bezerra; Cruz, Cinthia Maria Cordeiro Atanázio

2015-09-01

Determining heavy metal background concentrations in soils is fundamental in order to support the monitoring of potentially contaminated areas. This is particularly important to areas submitted to high environmental impact where an intensive and local monitoring is required. To this end, the aim of this study was to establish background concentrations and quality reference values (QRVs) for the heavy metals Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn, As, and Hg in an environmentally impacted watershed from Brazil. Geochemical associations among Fe, Mn, and trace elements were also assessed to provide an alternative tool for establishing background concentrations. A total of one hundred and four samples comprised twenty-six composite soil samples from areas of native forest or minimal anthropic influence. Samples were digested (USEPA method 3051A), and the metals were determined by ICP-OES, except for As and Hg measured by atomic absorption spectrophotometer. Background concentrations of heavy metals in soils had the following decreasing order: Fe > Mn > Zn > Cr > Pb > Ni > Cu > As > Cd > Hg. These values were usually lower than those observed in the international and national literature. The QRVs for Ipojuca watershed followed the order (mg kg(-1)) Fe (13,020.40) > Mn (91.80) > Zn (30.12) > Cr (15.00) > Pb (13.12) > Cu (3.53) > Ni (3.30) > As (0.51) > Cd (0.08) > Hg (0.04). Significant correlation among Fe, Mn, and heavy metals shows that solubilization by the method 3051A provides a reasonable estimate for predicting background concentrations for Cd, Cr, and Cu as well as Zn, Cr, Cu, and Ni.
[Determination of metals in waste bag filter of steel works by microwave digestion-flame atomic absorption spectrometry].

PubMed

Ning, Xun-An; Zhou, Yun; Liu, Jing-Yong; Wang, Jiang-Hui; Li, Lei; Ma, Xiao-Guo

2011-09-01

A method of microwave digestion technique-flame atomic absorption spectrometry was proposed to determine the total contents of Cu, Zn, Pb, Cd, Cr and Ni in five different kinds of waste bag filters from a steel plant. The digestion effects of the six acid systems on the heavy metals digestion were studied for the first time. The relative standard deviation (RSD) of the method was between 1.02% and 9.35%, and the recovery rates obtained by standard addition method ranged from 87.7% to 105.6%. The results indicated that the proposed method exhibited the advantages of simplicity, speediness, accuracy and repeatability, and it was suitable for determining the metal elements of the waste bag filter. The results also showed that different digestion systems should be used according to different waste bag filters. The waste bag filter samples from different production processes had different metal elements content. The Pb and Zn were the highest in the waste bag filters, while the Cu, Ni, Cd and Cr were relatively lower. These determination results provided the scientific data for further treatment and disposal of the waste bag filter.
Formation of the nitrogen aggregates in annealed diamond by neutron irradiation

NASA Astrophysics Data System (ADS)

Mita, Y.; Nisida, Y.; Okada, M.

2018-02-01

Neutron heavy irradiation was performed on synthetic diamonds contain nitrogen atoms in isolated substitutional form (called "type Ib diamond") and they were annealed under a pressure of 6 GPa. A large number of nitrogen B-aggregate which consists of four substitutional nitrogen atoms symmetrically surrounding a vacancy was formed within 30 m from single nitrogen atoms. Furthermore it is observed that, in these diamonds, single nitrogen atoms coexist with the B-aggregates, which is unexplainable by the simple nitrogen aggregation model.
Lifetimes and Oscillator Strengths for Ultraviolet Transitions Involving ns2nd 2D and nsnp2 2D terms in Pb II, Sn II, and Ge II

NASA Astrophysics Data System (ADS)

Federman, Steven Robert; Heidarian, Negar; Irving, Richard; Ellis, David; Ritchey, Adam M.; Cheng, Song; Curtis, Larry; Furman, Walter

2017-06-01

Radiative transitions of heavy elements are of great importance in astrophysics. Studying the transition rates and their corresponding oscillator strengths allows us to determine abundances of these heavy elements and therefore leads to better understanding of neutron capture processes. We provide the results of our studies on the transitions involving ns2nd 2D and nsnp2 2D terms to the ground term for Pb II, Sn II, and Ge II. These transitions are also of interest due to their strong mixing. Our studies involve experimental measurements performed at the Toledo Heavy Ion Accelerator and theoretical multi-configuration Dirac Hartree-Fock (MCDHF)1 calculations using the development version of the GRASP2K package2. The results are compared with Pb II lines seen in spectra acquired with the Hubble Space Telescope and with other values available in the literature. 1 P. Jönsson et al., The Computational Atomic Structure Group (2014).2 P. Jönsson et al., Comput. Phys. Commun. 184, 2197 (2013).
Kinetic and Potential Sputtering of Lunar Regolith: Contribution of Solar-Wind Heavy Ions

NASA Technical Reports Server (NTRS)

Meyer, F. W.; Harris, P. R.; Meyer, H. M., III; Hijiazi, H.; Barghouty, A. F.

2013-01-01

Sputtering of lunar regolith by protons as well as solar-wind heavy ions is considered. From preliminary measurements of H+, Ar+1, Ar+6 and Ar+9 ion sputtering of JSC-1A AGGL lunar regolith simulant at solar wind velocities, and TRIM simulations of kinetic sputtering yields, the relative contributions of kinetic and potential sputtering contributions are estimated. An 80-fold enhancement of oxygen sputtering by Ar+ over same-velocity H+, and an additional x2 increase for Ar+9 over same-velocity Ar+ was measured. This enhancement persisted to the maximum fluences investigated is approximately 1016/cm (exp2). Modeling studies including the enhanced oxygen ejection by potential sputtering due to the minority heavy ion multicharged ion solar wind component, and the kinetic sputtering contribution of all solar wind constituents, as determined from TRIM sputtering simulations, indicate an overall 35% reduction of near-surface oxygen abundance. XPS analyses of simulant samples exposed to singly and multicharged Ar ions show the characteristic signature of reduced (metallic) Fe, consistent with the preferential ejection of oxygen atoms that can occur in potential sputtering of some metal oxides.
High temperature electronic excitation and ionization rates in gases

NASA Technical Reports Server (NTRS)

Hansen, Frederick

1991-01-01

The relaxation times for electronic excitation due to electron bombardment of atoms was found to be quite short, so that electron kinetic temperature (T sub e) and the electron excitation temperature (T asterisk) should equilibrate quickly whenever electrons are present. However, once equilibrium has been achieved, further energy to the excited electronic states and to the kinetic energy of free electrons must be fed in by collisions with heavy particles that cause vibrational and electronic state transitions. The rate coefficients for excitation of electronic states produced by heavy particle collision have not been well known. However, a relatively simple semi-classical theory has been developed here which is analytic up to the final integration over a Boltzmann distribution of collision energies; this integral can then be evaluated numerically by quadrature. Once the rate coefficients have been determined, the relaxation of electronic excitation energy can be evaluated and compared with the relaxation rates of vibrational excitation. Then the relative importance of these two factors, electronic excitation and vibrational excitation by heavy particle collision, on the transfer of energy to free electron motion, can be assessed.
An Improved Analysis of the Sevoflurane-Benzene Structure by Chirped Pulse Ftmw Spectroscopy

NASA Astrophysics Data System (ADS)

Seifert, Nathan A.; Perez, Cristobal; Zaleski, Daniel P.; Neill, Justin L.; Pate, Brooks H.; Lesarri, Alberto; Vallejo, Montserrat; Cocinero, Emilio J.; Castano, Fernando; Kleiner, Isabelle

2013-06-01

Recent improvements to the 2-8 GHz CP-FTMW spectrometer at University of Virginia have improved the structural and spectroscopic analysis of the sevoflurane-benzene cluster. Previously reported results, although robust, were limited to a fit of the a-type transitions of the normal species in the determination of the six-fold barrier to benzene internal rotation. Structural analysis was limited to the benzene hydrogen atom positions using benzene-d_{1}. The increased sensitivity of the new 2-8 GHz setup allows for a full internal rotation analysis of the a- and c-type transitions of the normal species, which was performed with BELGI. A fit value for V_{6} of 32.868(11) cm^{-1} is determined. Additionally, a full substitution structure of the benzene carbon atom positions was determined in natural abundance. Also, new measurements of a sevoflurane/benzene-d_{1} mixture enabled detection of 33 of the 60 possible ^{2}D / ^{13}C double isotopologues. This abundance of isotopic data, a total of 45 isotopologues, enabled a full heavy atom least-squares r_{0} structure fit for the complex, including positions for all seven fluorines in sevoflurane. N. A. Seifert, D. P. Zaleski, J. L. Neill, B. H. Pate, A. Lesarri, M. Vallejo, E. J. Cocinero, F. Castańo. 67th OSU Int. Symp. On Mol. Spectrosc., Columbus, OH, 2012, MH13.
Monitorization of technosols in old mining sites treated with calcareous fillers

NASA Astrophysics Data System (ADS)

Martínez-Sanchez, MJose; Perez-Sirvent, Carmen; Garcia-Lorenzo, MariLuz; Gonzalez, Eva; Perez-Espinosa, Victor; Martínez-Lopez, Salvadora; Hernandez, Carmen; Molina, Jose; Martínez, Lucia B.

2014-05-01

A large number of soils around the world are contaminated by heavy metals due to mining activities, generating adverse effects on human health and the environment. In response to these negative effects, a variety of technologies to remediate soils affected by heavy metals have been developed. Among them, in situ immobilization by means of soil amendment is a non-intrusive and cost effective alternative, that transforms the highly mobile toxic heavy metals to physico-chemically stable forms, reducing their mobility and environmental risks. Limestone filler is a good selection for such a purpose, because of its low permeability and low solubility, due to its high degree of physical-chemical stability and because is a non-toxic material with a high finely divided calcium carbonate content. In addition, the use of this amendment could revalorize the residues, reducing the costs of the process. The objective of this work was to evaluate the effectiveness of a immobilization technique in sediments contaminated by heavy metals as a results of mining activities. The study area was Portman bay, located close to the mining region of La Unión and subjected to mining from the time of the Roman Empire to 1991. Wastes from mining activities mainly consisted in ore materials (galena, pyrite and sphalerite), phyllosilicates, in addition to siderite, iron oxides and sometimes alteration products such as jarosite, alunite, kaolinite and greenalite. These materials have suffered a concentration process by floatation with sea water and, as a result of the discharge, the whole of the bay has filled up with wastes which also extend into the Mediterranean Sea. Two experimental areas, approximately 1 Ha each one, were selected and technosols were developed as follows: original sediments from the bay, sediments mixed with limestone filler in a 1:1 proportion, gravel to avoid capillary and natural soil to allow plant growth. After the remediation technique was applied, monitorization of experimental areas was done in 18 sampling points in which sediment and water samples were collected and analyzed. Monitorization was carried out during a 4 years period, samples being obtained at two month intervals. The pH and the electrical conductivity were determined, in naddition to the heavy metal concentration. The Zn content was determined by flame atomic absorption spectrometry. The Pb, Cd and Cu content was determined by electrothermal atomization atomic absorption spectrometry. The As content was measured by atomic fluorescence spectrometry using an automated continuous flow hydride generation spectrometer. In addition, Microtox bioassay was applied in order to study ecotoxicity of collected water samples. Sediments before the remediation technique showed acidic pH, high EC values and high trace elements content. The results obtained after the immobilization showed that sediment samples had neutral pH (average value of 8.3) low electrical conductivity (1.32 dS m-1) and low trace elements concentration, in some cases below the detection limit. When water samples obtained in the piezometers were evaluated, the results indicated that these samples correspond to rainfall waters and were characterized by neutral pH and trace elements concentration below the detection limit. In addition, none of them showed toxicity when submitted to the selected bioassay Then, we can conclude that the use of limestone filler constitutes an excellent option in sediments polluted by trace elements, because of risk for human health or ecosystem does not exist or is decreased in a large extent after the intervention. In addition, the designed experience allows stabilizer proportion to be optimized and may suppose a big cost-saving in the project in areas affected by mining activities.
Upgrading of petroleum oil feedstocks using alkali metals and hydrocarbons

DOEpatents

Gordon, John Howard

2014-09-09

A method of upgrading an oil feedstock by removing heteroatoms and/or one or more heavy metals from the oil feedstock composition. This method reacts the oil feedstock with an alkali metal and an upgradant hydrocarbon. The alkali metal reacts with a portion of the heteroatoms and/or one or more heavy metals to form an inorganic phase separable from the organic oil feedstock material. The upgradant hydrocarbon bonds to the oil feedstock material and increases the number of carbon atoms in the product. This increase in the number of carbon atoms of the product increases the energy value of the resulting oil feedstock.
Computer Model Of Fragmentation Of Atomic Nuclei

NASA Technical Reports Server (NTRS)

Wilson, John W.; Townsend, Lawrence W.; Tripathi, Ram K.; Norbury, John W.; KHAN FERDOUS; Badavi, Francis F.

1995-01-01

High Charge and Energy Semiempirical Nuclear Fragmentation Model (HZEFRG1) computer program developed to be computationally efficient, user-friendly, physics-based program for generating data bases on fragmentation of atomic nuclei. Data bases generated used in calculations pertaining to such radiation-transport applications as shielding against radiation in outer space, radiation dosimetry in outer space, cancer therapy in laboratories with beams of heavy ions, and simulation studies for designing detectors for experiments in nuclear physics. Provides cross sections for production of individual elements and isotopes in breakups of high-energy heavy ions by combined nuclear and Coulomb fields of interacting nuclei. Written in ANSI FORTRAN 77.
Functionalizing carbon nitride with heavy atom-free spin converters for enhanced 1 O 2 generation

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

Wu, Wenting; Han, Congcong; Zhang, Qinhua

advanced photosensitizers for singlet oxygen (1O2) generation. However, the intersystem crossing (ISC) process is quite insufficient in carbon nitride, limiting the 1O2 generation. Here, we report a facile and general strategy to confined benzophenone as a heavy atom-free spin converter dopant in carbon nitride via the facile copolymerization. With proper energy level matching between the heavy atom-free spin converter and various ligands based on carbon nitride precursors, the proper combination can decrease the singlet-triplet energy gap (DEST) and hence generate 1O2 effectively. Due to its significant and selectivity for 1O2 generation, the as-prepared carbon nitride-based photosensitizer shows a high selectivemore » photooxidation activity for 1,5-dihydroxy-naphthalene (1,5-DHN). The product yield reached 71.8% after irradiation for 60 min, which was higher than that of cyclometalated PtII complexes (53.6%) in homogeneous photooxidation. This study can broaden the application of carbon nitride in the field of selective heterogeneous photooxidation due to simple operation, low cost, and high efficiency, making it a strong candidate for future industrialization.« less
The Complete Heavy-Atom Structure of a Cp-Ftmw Chiral Tag Precursor, Verbenone

NASA Astrophysics Data System (ADS)

Marshall, Frank E.; West, Channing; Sedo, Galen; Pate, Brooks; Grubbs, G. S., II

2017-06-01

The microwave spectrum of the chiral molecule verbenone has been recorded from 2-18 GHz using two CP-FTMW spectrometers. 2-8 GHz data has been acquired on a 2-8 GHz CP-FTMW located at the University of Virginia and 8-18 data has been acquired on a 6-18 GHz spectrometer located at Missouri S&T. From the experiments the authors were able to assign and fit isotopologues corresponding to each heavy atom position (either ^{13}C or ^{18}O), providing for the heavy-atom structure. Previous studies by Evans and coworkers have been added to these measurements in a global fit of the parent species. The measurement and assignment of these transitions provide preliminary information needed for enatiomeric excess experiments using CP-FTMW van der Waals-type chiral tagging processes already being performed at UVa. Details of the experiment, fits, and structure will be discussed. C. J. Evans, S. M. Allpress, P. D. Godfrey, D. McNaughton, 67th International Symposium on Molecular Spectroscopy, 2012, RH13 S. M. Allpress, Spectroscopic and Computational Chemistry Studies on Terpene Related Compounds, University of Leicester, 2015, Chapter 6: Microwave Spectroscopy of Verbenone
DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

This report contains viewgraphs on the following topics. The advanced light source U8 undulator beamline, 20--300 eV; gas-phase actinide studies with synchrotron radiation; atomic structure calculations for heavy atoms; flux growth of single crystal uranium intermetallics: Extension to transuranics; x-ray absorption near-edge structure studies of actinide compounds; surface as a new stage for studying actinides: Theoretical study of the surface electronic structure of uranium; magnetic x-ray scattering experiments at resonant energies; beamline instruments for radioactive materials; the search for x-ray absorption magnetic circular dichroism in actinide materials: preliminary experiments using UFe[sub 2] and U-S; the laser plasma laboratory light source:more » a source of preliminary transuranic data; electron spectroscopy of heavy fermion actinide materials; study of thin layers of actinides. Present status and future use of synchrotron radiation; electronic structure and correlated-electron theory for actinide materials; and heavy fermion and kondo phenomena in actinide materials.« less
DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

This report contains viewgraphs on the following topics. The advanced light source U8 undulator beamline, 20--300 eV; gas-phase actinide studies with synchrotron radiation; atomic structure calculations for heavy atoms; flux growth of single crystal uranium intermetallics: Extension to transuranics; x-ray absorption near-edge structure studies of actinide compounds; surface as a new stage for studying actinides: Theoretical study of the surface electronic structure of uranium; magnetic x-ray scattering experiments at resonant energies; beamline instruments for radioactive materials; the search for x-ray absorption magnetic circular dichroism in actinide materials: preliminary experiments using UFe{sub 2} and U-S; the laser plasma laboratory light source:more » a source of preliminary transuranic data; electron spectroscopy of heavy fermion actinide materials; study of thin layers of actinides. Present status and future use of synchrotron radiation; electronic structure and correlated-electron theory for actinide materials; and heavy fermion and kondo phenomena in actinide materials.« less
Heavy ions in Jupiter's environment

NASA Technical Reports Server (NTRS)

Brown, R. A.

1980-01-01

The extended atmosphere of the Jupiter system consists of atoms and ions of heavy elements. This material originates on the satellite Io. Energy is lost from the thermal plasma in collisionally excited optical and ultraviolet emission. The juxtaposition of Earth and spacecraft measurements provide insight concerning the underlying processes of particle transport and energy supply.
Processes of energy deposition by heavy-particle and electron impact. Final progress report

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

Salop, A.; Smith, F.T.

1978-04-18

Progress is reported in three areas of reasearch during the present period: K-shell ionization in high energy collisions of heavy ions with light target atoms using the sudden (Magnus) approximation, K-L level matching phenomena associated with K-shell vacancy production in heavy-ion collisions, and studies of low energy collisions of electrons with molecules using semi-classical perturbation theory. A brief discussion of each of these activities is given.
Hydroxide as general base in the saponification of ethyl acetate.

PubMed

Mata-Segreda, Julio F

2002-03-13

The second-order rate constant for the saponification of ethyl acetate at 30.0 degrees C in H(2)O/D(2)O mixtures of deuterium atom fraction n (a proton inventory experiment) obeys the relation k(2)(n) = 0.122 s(-1) M(-1) (1 - n + 1.2n) (1 - n + 0.48n)/(1 - n + 1.4n) (1 - n + 0.68n)(3). This result is interpreted as a process where formation of the tetrahedral intermediate is the rate-determining step and the transition-state complex is formed via nucleophilic interaction of a water molecule with general-base assistance from hydroxide ion, opposite to the direct nucleophilic collision commonly accepted. This mechanistic picture agrees with previous heavy-atom kinetic isotope effect data of Marlier on the alkaline hydrolysis of methyl formate.
Effective atomic number, energy loss and radiation damage studies in some materials commonly used in nuclear applications for heavy charged particles such as H, C, Mg, Fe, Te, Pb and U

NASA Astrophysics Data System (ADS)

Kurudirek, Murat

2016-05-01

Commonly used nuclear physics materials such as water, concrete, Pb-glass, paraffin, freon and P 10 gases, some alloys such as brass, bronze, stainless-steel and some scintillators such as anthracene, stilbene and toluene have been investigated with respect to the heavy charged particle interaction as means of projected range and effective atomic number (Zeff) in the energy region 10 keV to 10 MeV. Calculations were performed for heavy ions such as H, C, Mg, Fe, Te, Pb and U. Also, the energy loss and radiation damage were studied using SRIM Monte Carlo code for anthracene for different heavy ions of 100 keV kinetic energy. It has been observed that the variation in Zeff becomes less when the atomic number of the ions increase. Glass-Pb, bronze, brass, stainless-steel and Freon gas were found to vary less than 10% in the energy region 10 keV to 10 MeV. For total proton interaction, discrepancies up to 10% and 18% between two databases namely PSTAR and SRIM were noted in mass stopping power and Zeff of water, respectively. The range calculations resulted with a conclusion that the metal alloys and glass-Pb have lowest values of ranges confirming best shielding against energetic heavy ions whereas freon and P 10 gases have the highest values of ranges in the entire energy region. The simulation results showed that the energy loss (%) to target electrons decreases as the Z of the incident ion increases. Also, it was observed that the radiation damage first increases with Z of the ion and then keeps almost constant for ions with Z≥52.

A simple scheme for magnetic balance in four-component relativistic Kohn-Sham calculations of nuclear magnetic resonance shielding constants in a Gaussian basis.

PubMed

Olejniczak, Małgorzata; Bast, Radovan; Saue, Trond; Pecul, Magdalena

2012-01-07

We report the implementation of nuclear magnetic resonance (NMR) shielding tensors within the four-component relativistic Kohn-Sham density functional theory including non-collinear spin magnetization and employing London atomic orbitals to ensure gauge origin independent results, together with a new and efficient scheme for assuring correct balance between the large and small components of a molecular four-component spinor in the presence of an external magnetic field (simple magnetic balance). To test our formalism we have carried out calculations of NMR shielding tensors for the HX series (X = F, Cl, Br, I, At), the Xe atom, and the Xe dimer. The advantage of simple magnetic balance scheme combined with the use of London atomic orbitals is the fast convergence of results (when compared with restricted kinetic balance) and elimination of linear dependencies in the basis set (when compared to unrestricted kinetic balance). The effect of including spin magnetization in the description of NMR shielding tensor has been found important for hydrogen atoms in heavy HX molecules, causing an increase of isotropic values of 10%, but negligible for heavy atoms.
Nondestructive Determination of Cu Residue in Orange Peel by Laser Induced Breakdown Spectroscopy

NASA Astrophysics Data System (ADS)

Hu, Huiqin; Huang, Lin; Liu, Muhua; Chen, Tianbing; Yang, Ping; Yao, Mingyin

2015-08-01

Laser induced breakdown spectroscopy (LIBS) is an emerging tool with rapid, nondestructive, green characteristics in qualitative or quantitative analyses of composition in materials. But LIBS has its shortcomings in detect limit and sensitivity. In this work, heavy metal Cu in Gannan Navel Orange, which is one of famous fruits from Jiangxi of China, was analyzed. In view of LIBS's limit, it is difficult to determinate heavy metals in natural fruits. In this work, nine orange samples were pretreated in 50-500 μg/mL Cu solution, respectively. Another one orange sample was chosen as a control group without any pollution treatment. Previous researchers observed that the content of heavy metals is much higher in peel than in pulp. So, the content in pulp can be reflected by detecting peel. The real concentrations of Cu in peels were acquired by atomic absorption spectrophotometer (AAS). A calibration model of Cu I 324.7 and Cu I 327.4 was constructed between LIBS intensity and AAS concentration by six samples. The correlation coefficient of the two models is also 0.95. All of the samples were used to verify the accuracy of the model. The results show that the relative error (RE) between predicted and real concentration is less than 6.5%, and Cu I 324.7 line has smaller RE than Cu I 327.4. The analysis demonstrated that different characteristic lines decided different accuracy. The results prove the feasibility of detecting heavy metals in fruits by LIBS. But the results are limited in treated samples. The next work will focus on direct analysis of heavy metals in natural fruits without any pretreatment. This work is helpful to explore the distribution of heavy metals between pulp and peel. supported by National Natural Science Foundation of China (No. 31460419) and Major Project of Science and Technology of Jiangxi, China (No. 20143ACB21013)
Microwave spectrum and structure of bicyclo /1.1.1/ pentanone and comparison with several theoretical structures

NASA Technical Reports Server (NTRS)

Mcrae, Glenn A.; Cohen, Edward A.; Sponsler, Michael B.; Dougherty, Dennis A.

1986-01-01

The microwave spectra of five isotopic species of bicyclo (1.1.1) pentanone have been investigated. The rotational constants along with various centrifugal distortion constants for each species have been determined. From the rotational constants, a complete r(s) structure has been determined for the heavy atoms. Analysis of Stark effect measurements has shown the dipole moment to be along the a principal inertial axis with a magnitude of 3.164 (5) D. These results are compared with those obtained by four current theoretical methods: molecular mechanics (MM2), MNDO, and Hartree-Fock ab initio theory with STO-3G and 3-21G basis sets.
Upper bound dose values for meson radiation in heavy-ion therapy.

PubMed

Rabin, C; Gonçalves, M; Duarte, S B; González-Sprinberg, G A

2018-06-01

Radiation treatment of cancer has evolved to include massive particle beams, instead of traditional irradiation procedures. Thus, patient doses and worker radiological protection have become issues of constant concern in the use of these new technologies, especially for proton- and heavy-ion-therapy. In the beam energies of interest of heavy-ion-therapy, secondary particle radiation comes from proton, neutron, and neutral and charged pions produced in the nuclear collisions of the beam with human tissue atoms. This work, for the first time, offers the upper bound of meson radiation dose in organic tissues due to secondary meson radiation in heavy-ion therapy. A model based on intranuclear collision has been used to follow in time the nuclear reaction and to determine the secondary radiation due to the meson yield produced in the beam interaction with nuclei in the tissue-equivalent media and water. The multiplicity, energy spectrum, and angular distribution of these pions, as well as their decay products, have been calculated in different scenarios for the nuclear reaction mechanism. The results of the produced secondary meson particles has been used to estimate the energy deposited in tissue using a cylindrical phantom by a transport Monte Carlo simulation and we have concluded that these mesons contribute at most 0.1% of the total prescribed dose.
Pollution Problem in River Kabul: Accumulation Estimates of Heavy Metals in Native Fish Species

PubMed Central

Ahmad, Habib; Yousafzai, Ali Muhammad; Siraj, Muhammad; Ahmad, Rashid; Ahmad, Israr; Nadeem, Muhammad Shahid; Ahmad, Waqar; Akbar, Nazia; Muhammad, Khushi

2015-01-01

The contamination of aquatic systems with heavy metals is affecting the fish population and hence results in a decline of productivity rate. River Kabul is a transcountry river originating at Paghman province in Afghanistan and inters in Khyber Pakhtunkhwa province of Pakistan and it is the major source of irrigation and more than 54 fish species have been reported in the river. Present study aimed at the estimation of heavy metals load in the fish living in River Kabul. Heavy metals including chromium, nickel, copper, zinc, cadmium, and lead were determined through atomic absorption spectrophotometer after tissue digestion by adopting standard procedures. Concentrations of these metals were recorded in muscles and liver of five native fish species, namely, Wallago attu, Aorichthys seenghala, Cyprinus carpio, Labeo dyocheilus, and Ompok bimaculatus. The concentrations of chromium, nickel, copper, zinc, and lead were higher in both of the tissues, whereas the concentration of cadmium was comparatively low. However, the concentration of metals was exceeding the RDA (Recommended Dietary Allowance of USA) limits. Hence, continuous fish consumption may create health problems for the consumers. The results of the present study are alarming and suggest implementing environmental laws and initiation of a biomonitoring program of the river. PMID:26339622
Community-level physiological profiles of microorganisms inhabiting soil contaminated with heavy metals

NASA Astrophysics Data System (ADS)

Kuźniar, Agnieszka; Banach, Artur; Stępniewska, Zofia; Frąc, Magdalena; Oszust, Karolina; Gryta, Agata; Kłos, Marta; Wolińska, Agnieszka

2018-01-01

The aim of the study was to assess the differences in the bacterial community physiological profiles in soils contaminated with heavy metals versus soils without metal contaminations. The study's contaminated soil originated from the surrounding area of the Szopienice non-ferrous metal smelter (Silesia Region, Poland). The control was soil unexposed to heavy metals. Metal concentration was appraised by flame atomic absorption spectrometry, whereas the the community-level physiological profile was determined with the Biolog EcoPlatesTM system. The soil microbiological activity in both sites was also assessed via dehydrogenase activity. The mean concentrations of metals (Cd and Zn) in contaminated soil samples were in a range from 147.27 to 12265.42 mg kg-1, and the heavy metal contamination brought about a situation where dehydrogenase activity inhibition was observed mostly in the soil surface layers. Our results demonstrated that there is diversity in the physiological profiles of microorganisms inhabiting contaminated and colntrol soils; therefore, for assessment purposes, these were treated as two clusters. Cluster I included colntrol soil samples in which microbial communities utilised most of the available substrates. Cluster II incorporated contaminated soil samples in which a smaller number of the tested substrates was utilised by the contained microorganisms. The physiological profiles of micro-organisms inhabiting the contaminated and the colntrol soils are distinctly different.
Evaluation of heavy metal pollution in water wells and soil using common leafy green plant indicators in the Al-Kharj region, Saudi Arabia.

PubMed

Al-Hammad, Bushra Ahmed; Abd El-Salam, Magda Magdy

2016-06-01

This study was performed to determine the levels of eight heavy metals in irrigation well water and soil and to assess the suitability of some leafy green plants that are commonly cultivated in the Al-Kharj region, Saudi Arabia, for human consumption using an atomic absorption spectrometer. The mean concentrations of metals ranged from 0.0001 to 0.436 mg/L in well water and from 0.248 to 164.52 mg/kg in soil. The heavy metal concentrations showed significant differences among the different leafy green plants studied. Parsley (4.98 mg/kg) exhibited higher levels of Pb than other leafy green plants, whereas mallow (0.097 mg/kg) revealed greater amounts of Cd than other plants. All of the leafy green plants retained essential metals (Cu, Zn, Fe and Mn) more than the toxic metals (Pb and Cd). The levels of some of the metals in the leafy green plants were found to meet the FAO/WHO-recommended limits. The monitoring of heavy metals in leafy green plants must be continued because these plants are the main source of food for humans in many parts of the world and are considered to be bio-indicators for environmental pollution.
Acid volatile sulfide and simultaneously extracted metals in superficial sediments from Baihua Lake, China

NASA Astrophysics Data System (ADS)

Zhang, Jiping; Hu, Jiwei; Huang, Xianfei; Shen, Wei; Jin, Mei; Fu, Liya; Jin, Xiaofei

2013-09-01

The bioavailability of five divalent cationic heavy metals (Pb, Cd, Cu, Zn and Ni) in 10 superficial sediment samples from Baihua Lake was assessed based on the molar ratio of simultaneously extracted metals (SEMs) to acid volatile sulfide (AVS). Atomic absorption spectrometry (AAS) and X-ray powder diffraction (XRD) were used to determine the heavy metal concentrations and examine the mineralogy of the crystalline phases, respectively. The AVS loadings in sediments from Baihua Lake ranged from 64.30 to 350.08 μmol/g (dry weight). The corresponding SEM levels for the sampling sites varied from 1.770 to 14.660 μmol/g. The molar ratio of SEMs to AVS ranged from 0.014 to 0.084 with a mean value of 0.034. The XRD analysis also confirmed the presence of some metal sulfides in sediments from Baihua Lake. The SEMs/AVS ratios for all sampling sites were significantly lower than 1.0, indicating that AVS in the sediments was sufficient to bind the five heavy metals; thus, these heavy metals are currently not significantly bioavailable to benthic organisms. Comparing the SEMs results to published guideline values for metal toxicity to benthic organisms in sediments, however, suggests that Zn and Ni pose a risk at some sampling locations in Baihua Lake.
Temporal variations of heavy metals levels in Perna viridis, on the Chacopata-Bocaripo lagoon axis, Sucre State, Venezuela.

PubMed

Pinto, Rafael; Acosta, Vanessa; Segnini, Mary Isabel; Brito, Leonor; Martínez, Gregorio

2015-02-28

Perna viridis was used as biomonitor to assess heavy metal levels in the Chacopata-Bocaripo lagoon axis, Venezuela, during rain and drought seasons. The mussels were weighed and measured. The metal concentrations were determined by atomic absorption spectrophotometry. For rain period, the order of bioavailability was: Cu>Ni>Mn>Co>Cd>Pb, and for drought: Cu>Mn>Ni>Co>Pb>Cd. The concentrations of Ni, Co, Cd and Pb showed significant differences (P<0.05) in both periods. There was higher metal accumulation during drought season, possibly related to upwelling, since it produces an increase in primary productivity, which translates more food into organisms, making metals bioavailable for mussels. Only Cu and Mn showed significant relationships between the size and metal concentration, during drought period, it may be because of the organisms need for these essential metals in different physiological processes. Copyright © 2014 Elsevier Ltd. All rights reserved.
Mineral and heavy metal levels of some fruits grown at the roadsides.

PubMed

Hamurcu, Mehmet; Ozcan, Mehmet Musa; Dursun, Nesim; Gezgin, Sait

2010-06-01

The rate of heavy metal pollution of some minor fruit samples growing at the roadsides in Turkey were determined by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES). Pb, Zn and Cu were found at the high levels in the fruit samples. The results showed that the average level of Cu changed between 0.27 mg/kg (Sample 11) and 0.05 mg/kg (Sample 15), Cr 0.32 mg/kg (Sample 14) and 0.18 mg/kg (Sample 13), Ni 0.68 mg/kg (Sample 12) and 0.26 g/kg (Sample 15), Pb 2.86 mg/kg (Sample 12) and 1.54 mg/kg (Sample 4) and Se 12.96 mg/kg (Sample 14) and 5.42 mg/kg (Sample 7). The levels of Cu, Cd and Cr in samples do not appear to reach pollution levels. Copyright 2010 Elsevier Ltd. All rights reserved.
Honeybees and honey as monitors for heavy metal contamination near thermal power plants in Mugla, Turkey.

PubMed

Silici, Sibel; Uluozlu, Ozgur Dogan; Tuzen, Mustafa; Soylak, Mustafa

2016-03-01

In the present work, 6 honeydew samples of known geographical and botanical origins and 11 honeybee samples were analyzed to detect possible contamination by the thermoelectric power plants in Mugla, Turkey. The contents of trace elements were determined by atomic absorption spectrometry after application of microwave digestion. The samples from the thermal power plants, which were 10-22 km away from the hives, that did not cause pollution in honeydew honeys were also analyzed. The levels of copper, cadmium (Cd), lead (Pb), zinc, manganese, iron, chromium, nickel, and aluminum were similar to the values found in other recent studies in literature. However, it was found that the contamination levels of the toxic elements such as Pb and Cd in honeybee samples measured relatively higher than that of honey samples. The study concludes that honeybees may be better bioindicators of heavy metal pollution than honey. © The Author(s) 2013.
Levels of Heavy Metals in Popular Cigarette Brands and Exposure to These Metals via Smoking

PubMed Central

Ashraf, Muhammad Waqar

2012-01-01

The levels of selected heavy metals in popular cigarette brands sold and/or produced in Saudi Arabia were determined by graphite furnace-atomic absorption spectrometry (GFAAS). Average concentrations of Cadmium and Lead in different cigarette brands were 1.81 and 2.46 μg g−1 (dry weight), respectively. The results obtained in this study estimate the average quantity of Cd inhaled from smoking one packet of 20 cigarettes to be in the range of 0.22–0.78 μg. Results suggest that the quantity of Pb inhaled of smoking one packet of 20 cigarettes is estimated to be 0.97–2.64 μg. The concentrations of Cd and Pb in cigarettes were significantly different between cigarette brands tested. The results of the present study were compared with those of other regional and international studies. PMID:22489199
Heavy metal extractable forms in sludge from wastewater treatment plants.

PubMed

Alvarez, E Alonso; Mochón, M Callejón; Jiménez Sánchez, J C; Ternero Rodríguez, M

2002-05-01

The analysis of heavy metals is a very important task to assess the potential environmental and health risk associated with the sludge coming from wastewater treatment plants (WWTPs). However, it is widely accepted that the determination of total elements does not give an accurate estimation of the potential environmental impact. So, it is necessary to apply sequential extraction techniques to obtain a suitable information about their bioavailability or toxicity. In this paper, a sequential extraction scheme according to the BCR's guidelines was applied to sludge samples collected from each sludge treatment step of five municipal activated sludge plants. Al. Cd, Co, Cu, Cr, Fe, Mn, Hg, Mo, Ni, Pb, Ti and Zn were determined in the sludge extracts by inductively coupled plasma atomic emission spectrometry. In relation to current international legislation for the use of sludge for agricultural purposes none of metal concentrations exceeded maximum permitted levels. In most of the metal elements under considerations, results showed a clear rise along the sludge treatment in the proportion of two less-available fractions (oxidizable metal and residual metal).
Investigation of heavy metal content of Turkish tobacco leaves, cigarette butt, ash, and smoke.

PubMed

Pelit, Füsun Okçu; Demirdöğen, Ruken Esra; Henden, Emür

2013-11-01

A procedure for the determination of cadmium, copper, manganese, and zinc in Turkish tobaccos, which were of different origins, years, and grades, and in the butt, ash, and smoke, which were obtained by smoking the cigarettes that were prepared manually from the said tobaccos in a smoking apparatus, was devised as proposed. The collected samples were digested by wet ashing technique by using HNO3-HClO4 and were analyzed by flame atomic absorption spectrometry with satisfactory recoveries (94% to 98%). The regression coefficients were above 0.99, and the detection limits were in the range of 0.03-0.12 mg/L(-1). The performance and accuracy of the method was tested by analyzing "Certified Reference Material GBW 08501-Peach Leaves." The determined values were in agreement with the standard values for the heavy metals analyzed. Thus, it was concluded that the developed method could offer a wide range of application for establishing a relationship between the makeup and composition of tobacco plant, products, ash, smoke, and smoking.
The unitary convolution approximation for heavy ions

NASA Astrophysics Data System (ADS)

Grande, P. L.; Schiwietz, G.

2002-10-01

The convolution approximation for the impact-parameter dependent energy loss is reviewed with emphasis on the determination of the stopping force for heavy projectiles. In this method, the energy loss in different impact-parameter regions is well determined and interpolated smoothly. The physical inputs of the model are the projectile-screening function (in the case of dressed ions), the electron density and oscillators strengths of the target atoms. Moreover, the convolution approximation, in the perturbative mode (called PCA), yields remarkable agreement with full semi-classical-approximation (SCA) results for bare as well as for screened ions at all impact parameters. In the unitary mode (called UCA), the method contains some higher-order effects (yielding in some cases rather good agreement with full coupled-channel calculations) and approaches the classical regime similar as the Bohr model for large perturbations ( Z/ v≫1). The results are then used to compare with experimental values of the non-equilibrium stopping force as a function of the projectile charge as well as with the equilibrium energy loss under non-aligned and channeling conditions.
[Determination of heavy metals for RoHS compliance by ICP-OES spectrometry coupled with microwave extraction system].

PubMed

Hua, Li; Wu, Yi-Ping; An, Bing; Lai, Xiao-Wei

2008-11-01

The harm of heavy metals contained in electronic and electrical equipment (EEE) on environment is of high concern by human. Aiming to handle the great challenge of RoHS compliance, the determinations of trace or ultratrace chromium (Cr), cadmium (Cd), mercury (Hg) and lead (Pb) by inductively coupled plasma optical emission spectrometry (ICP-OES) was performed in the present paper, wherein, microwave extraction technology was used to prepare the sample solutions. In addition, the precision, recovery, repeatability and interference issues of this method were also discussed. The results exhibited that using the microwave extraction system to prepare samples is more quick, lossless, contamination-free in comparison with the conventional extraction methods such as dry ashing, wet-oven extraction etc. By analyzing the recoveries of these four heavy metals over different working time and wavelengths, the good recovery range between 85% and 115% showed that there was only tiny loss or contamination during the process of microwave extraction, sample introduction and ICP detection. Repeatability experiments proved that ICP plasma had a good stability during the working time and the matrix effect was small. Interference was a problem troublesome for atomic absorption spectrometry (AAS), however, the techniques of standard additions or inter-element correction (IEC) method can effectively eliminated the interferences of Ni, As, Fe etc. with the Cd determination. By employing the multi-wavelengths and two correction point methods, the issues of background curve sloping shift and spectra overlap were successfully overcome. Besides, for the determinations of trace heavy metal elements, the relative standard deviation (RSD) was less than 3% and the detection limits were less than 1 microg x L(-10 (3sigma, n = 5) for samples, standard solutions, and standard additions, which proved that ICP-OES has a good precision and high reliability. This provided a reliable technique support for electronic and electrical (EE) industries to comply with RoHS directive.
Electronic excitation of ground state atoms by collision with heavy gas particles

NASA Technical Reports Server (NTRS)

Hansen, C. Frederick

1993-01-01

Most of the important chemical reactions which occur in the very high temperature air produced around space vehicles as they enter the atmosphere were investigated both experimentally and theoretically, to some extent at least. One remaining reaction about which little is known, and which could be quite important at the extremely high temperatures that will be produced by the class of space vehicles now contemplated - such as the AOTV - is the excitation of bound electron states due to collisions between heavy gas particles. Rates of electronic excitation due to free electron collisions are known to be very rapid, but because these collisions quickly equilibrate the free and bound electron energy, the approach to full equilibrium with the heavy particle kinetic energy will depend primarily on the much slower process of bound electron excitation in heavy particle collisions and the subsequent rapid transfer to free electron energy. This may be the dominant mechanism leading to full equilibrium in the gas once the dissociation process has depleted the molecular states so the transfer between molecular vibrational energy and free electron energy is no longer available as a channel for equilibration of free electron and heavy particle kinetic energies. Two mechanisms seem probable in electronic excitation by heavy particle impact. One of these is the collision excitation and deexcitation of higher electronic states which are Rydberg like. A report, entitled 'Semi-Classical Theory of Electronic Excitation Rates', was submitted previously. This presented analytic expressions for the transition probabilities, assuming that the interaction potential is an exponential repulsion with a perturbation ripple due to the dipole-induced dipole effect in the case of neutral-neutral collisions, and to the ion-dipole interaction in the case of ion-neutral collisions. However the above may be, there is little doubt that excitation of ground state species by collision occurs at the point where the initial and final potentials cross, or at least come very close. Therefore, this mechanism would be applicable to the case where a gas is initially at very low temperature suddenly subjected to high energy heavy particle bombardment. This situation would model the measurement of excitation cross section by molecular beam techniques, for example. The purpose is to report values of cross sections and rate coefficients for collision excitation of ground state atoms estimated with the Landau-Zener transition theory and to compare results with measurement of excitation cross sections for a beam of Hydrogen atoms impacting Argon atom targets. Some very dubious approximations are used, and the comparison with measurement is found less than ideal, but results are at least consistent within order of magnitude. The same model is then applied to the case of N-N atom collisions, even though the approximations then become even more doubtful. Still the rate coefficients obtained are at least plausible in both magnitude and functional form, and as far as I am aware these are the only estimates available for such rate coefficients.
UV-spektra från Hubble-teleskopet avslöjar en stjärna i Vargen som lagrar tunga isotoper av mycket tunga grundämnen.

NASA Astrophysics Data System (ADS)

Johansson, S. E.; Leckrone, D. S.; Wahlgren, G. M.

1994-09-01

UV spectra from the Hubble Space Telescope reveal a star that stores heavy isotopes of very heavy elements. Atomic and plasma physics arguments for UV spectroscopy from space borne observatories are given. As an example, the authors discuss the analysis of high resolution spectra of the chemically peculiar star χ Lupi, obtained with the Hubble Space Telescope, in terms of identification of spectral lines of very heavy elements.
Mineral and heavy metal contents of the outer and inner tissues of commonly used fruits.

PubMed

Özcan, Mehmet Musa; Harmankaya, Mustafa; Gezgin, Sait

2012-01-01

The rate of heavy metal pollution in some minor fruit samples growing at roadsides in Turkey were determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES). The mineral contents of samples were found to be different depending on the several parts Citrus fruits. The highest minor and heavy metal levels for Citrus fruits were determined between 17.24 and 45.30 mg/kg boron, 2.08 and 15.05 mg/kg copper, 1.01 and 16.00 mg/kg iron and 2.35 and 9.87 mg/kg zinc. Boron content ranged from 16.54 mg/kg (Deveci pear inner pulp) to 89.89 mg/kg (Arjantin apple outer skin). The level of Fe ranged from 1.49 mg/kg (quince pulp) to 25.05 mg/kg (Ankara pear pulp). Cu content of fruits ranged between 2.52 mg/kg (Fuji apple skin) and 25.93 mg/kg quince skin). Zn content was found between 0.46 mg/kg (Golden apple pulp) and 14.34 mg/kg (quince skin). P contents ranged from 651 mg/kg (Golden apple pulp) to 1269 mg/kg (quince skin). Na was found between 500 mg/kg (Fuji apple skin) and 907 mg/kg (Arjantin apple skin).
Focal-surface detector for heavy ions

DOEpatents

Erskine, John R.; Braid, Thomas H.; Stoltzfus, Joseph C.

1979-01-01

A detector of the properties of individual charged particles in a beam includes a gridded ionization chamber, a cathode, a plurality of resistive-wire proportional counters, a plurality of anode sections, and means for controlling the composition and pressure of gas in the chamber. Signals generated in response to the passage of charged particles can be processed to identify the energy of the particles, their loss of energy per unit distance in an absorber, and their angle of incidence. In conjunction with a magnetic spectrograph, the signals can be used to identify particles and their state of charge. The detector is especially useful for analyzing beams of heavy ions, defined as ions of atomic mass greater than 10 atomic mass units.

Heavy metal contamination and risk assessment in water, paddy soil, and rice around an electroplating plant.

PubMed

Liu, Jie; Zhang, Xue-Hong; Tran, Henry; Wang, Dun-Qiu; Zhu, Yi-Nian

2011-11-01

The objective of this paper is to assess the impact of long-term electroplating industrial activities on heavy metal contamination in agricultural soils and potential health risks for local residents. Water, soil, and rice samples were collected from sites upstream (control) and downstream of the electroplating wastewater outlet. The concentrations of heavy metals were determined by an atomic absorption spectrophotometer. Fractionation and risk assessment code (RAC) were used to evaluate the environmental risks of heavy metals in soils. The health risk index (HRI) and hazard index (HI) were calculated to assess potential health risks to local populations through rice consumption. Hazardous levels of Cu, Cr, and Ni were observed in water and paddy soils at sites near the plant. According to the RAC analysis, the soils showed a high risk for Ni and a medium risk for Cu and Cr at certain sites. The rice samples were primarily contaminated with Ni, followed by Cr and Cu. HRI values >1 were not found for any heavy metal. However, HI values for adults and children were 2.075 and 1.808, respectively. Water, paddy soil, and rice from the studied area have been contaminated by Cu, Cr, and Ni. The contamination of these elements is related to the electroplating wastewater. Although no single metal poses health risks for local residents through rice consumption, the combination of several metals may threaten the health of local residents. Cu and Ni are the key components contributing to the potential health risks.
Association between serum heavy metals level and cancer incidence in darbandikhan and Kalar Area, Kurdistan Region, Iraq.

PubMed

Marouf, B H

2018-06-01

: Exposure to heavy metals is considered as the main threat to human health and biological system. Darbandikhan Lake is one of the three large lakes in Kurdistan, Northern Iraq; it is currently at a high risk of pollution by sewage and municipal wastes. The current study was designed to highlight the potential association between concentration of heavy metals and carcinogenicity in people who live in Darbandikhan and the surrounding area. : A case-control study was carried out on 29 cancerous patients and 25 healthy individuals from Darbandikhan, Kalar, and the surrounding area; the patients were admitted to the Hiwa Oncology Center in Sulaimani City. Determination of serum concentrations of copper (Cu), iron (Fe), cadmium (Cd), arsenic (As), chromium (Cr), lead (Pb), and zinc (Zn), was performed by an inductively coupled plasma atomic absorption spectrophotometer. : Serum concentration of Pb, Fe, and Cu was higher in cancer group compared with control in nonsignificantly different (P > 0.05) for Pb, whereas significantly (P < 0.05) for Cu and Fe. Higher serum Cd concentration was detected in control group compared with the cancer group. Differences not detected in Cr and As serum concentration analysis between both groups. Serum level of Zn was nonsignificantly higher in control group compared with the cancer group (P > 0.05). Discrepancies in the serum level of heavy metals of cancer group might reveal the involvement of heavy metal as a contributing factor of carcinogenicity in these areas.
Minima in generalized oscillator strengths for initially excited hydrogen-like atoms

NASA Technical Reports Server (NTRS)

Matsuzawa, M.; Omidvar, K.; Inokuti, M.

1976-01-01

Generalized oscillator strengths for transitions from an initially excited state of a hydrogenic atom to final states (either discrete or continuum) have complicated structures, including minima and shoulders, as functions of the momentum transfer. Extensive calculations carried out in the present work have revealed certain systematics of these structures. Some implications of the minima to the energy dependence of the inner-shell ionization cross section of heavy atoms by proton impact are discussed.
Comparison of lead and cadmium contents in cruciferous vegetables grown under diversified ecological conditions: Cracow region of Poland.

PubMed

Kapusta-Duch, Joanna; Leszczyńska, Teresa; Florkiewicz, Adam; Filipiak-Florkiewicz, Agnieszka

2011-01-01

The aim of the present study was to compare lead and cadmium contents in cruciferous vegetables grown under diversified ecological conditions for three consecutive years, independently of the climatic and agrotechnical conditions. The research was conducted in the Cracow region of Poland and tests vegetables near the Steelworks, from ecological farms, and from local markets. The heavy metal contents were determined using the validated Atomic Absorption Spectrometry method, including electrothermal atomization, with an ET-AAS graphite cuvette (Varian AA240Z, made by Varian). Cruciferous vegetables cultivated in the areas surrounding the steelworks were characterized by alarmingly high lead content versus ecological and commercially available vegetables, while the contents of this metal in vegetables from the two latter locations did not differ. It cannot be definitively stated that the origin of vegetables influenced their cadmium content.
[Variation in soil Mn fractions as affected by long-term manure amendment using atomic absorption spectrophotometer in a typical grassland of inner Mongolia].

PubMed

Fu, Ming-ming; Jiang, Yong; Bai, Yong-fei; Zhang, Yu-ge; Xu, Zhu-wen; Li, Bo

2012-08-01

The effect of sheep manure amendment on soil manganese fractions was conducted in a 11 year experiment at inner Mongolia grassland, using sequential extraction procedure in modified Community Bureau of Reference, and determined by atomic absorption spectrophotometer. Five treatments with dry sheep manure addition rate 0, 50, 250, 750, and 1500 g x m(-2) x yr(-1), respectively, were carried out in this experiment. Results showed that the recovery rate for total Mn was 91.4%-105.9%, as the percentage recovered from the summation of the improved BCR results with aqua regia extractable contents, and it was 97.2%-102.9% from certified soil reference materials. Plant available exchangeable Mn could be enhanced by 47.89%, but reducible and total Mn contents decreased significantly under heavy application of manure at depth of 0-5 cm. The effect of manure amendment on Mn fractions was greater in 0-5 cm than in 5-10 cm soil layer. The results are benefit to micronutrient fractions determination and nutrient management in grassland soils.
Pushing the limits of sulfur SAD phasing: de novo structure solution of the N-terminal domain of the ectodomain of HCV E1

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

El Omari, Kamel; Iourin, Oleg; Kadlec, Jan

2014-08-01

The sulfur SAD phasing method was successfully used to determine the structure of the N-terminal domain of HCV E1 from low-resolution diffracting crystals by combining data from 32 crystals. Single-wavelength anomalous dispersion of S atoms (S-SAD) is an elegant phasing method to determine crystal structures that does not require heavy-atom incorporation or selenomethionine derivatization. Nevertheless, this technique has been limited by the paucity of the signal at the usual X-ray wavelengths, requiring very accurate measurement of the anomalous differences. Here, the data collection and structure solution of the N-terminal domain of the ectodomain of HCV E1 from crystals that diffractedmore » very weakly is reported. By combining the data from 32 crystals, it was possible to solve the sulfur substructure and calculate initial maps at 7 Å resolution, and after density modication and phase extension using a higher resolution native data set to 3.5 Å resolution model building was achievable.« less
Collisional Cooling of Light Ions by Cotrapped Heavy Atoms.

PubMed

Dutta, Sourav; Sawant, Rahul; Rangwala, S A

2017-03-17

We experimentally demonstrate cooling of trapped ions by collisions with cotrapped, higher-mass neutral atoms. It is shown that the lighter ^{39}K^{+} ions, created by ionizing ^{39}K atoms in a magneto-optical trap (MOT), when trapped in an ion trap and subsequently allowed to cool by collisions with ultracold, heavier ^{85}Rb atoms in a MOT, exhibit a longer trap lifetime than without the localized ^{85}Rb MOT atoms. A similar cooling of trapped ^{85}Rb^{+} ions by ultracold ^{133}Cs atoms in a MOT is also demonstrated in a different experimental configuration to validate this mechanism of ion cooling by localized and centered ultracold neutral atoms. Our results suggest that the cooling of ions by localized cold atoms holds for any mass ratio, thereby enabling studies on a wider class of atom-ion systems irrespective of their masses.
The Synthesis and Photophysical Characterization of Porphyrin Photoactive Materials for Use as Sensitizers in Organic Photovoltaics and Photodynamic Therapy

NASA Astrophysics Data System (ADS)

Marin, Dawn Marie

Solar energy conversion and photodynamic therapy (PDT) are very different applications. However, both utilize very similar photoactive molecules called porphyrins. Porphyrins are structural analogs of chlorophyll and also function as prosthetic groups in some biological enzymes. Understanding the structure/function relationship of these molecules is crucial for enhancing the energy generation efficiency of molecular solar cells and improving chemotherapeutic activity in PDT. In this dissertation, two approaches were applied with the goal of increasing the efficiency of molecular semiconductors for these applications: the heavy atom effect and donor-acceptor molecules. We enhanced the efficiency of triplet excited state formation and singlet oxygen generation for porphyrin sensitizers using the heavy atom effect. The heavy atom effect induces spin-orbit coupling to promote intersystem crossing into the triplet state. In this study, a carbomethoxyphenyl substituent was replaced with either a bromophenyl or an iodophenyl substituent on 5,10,15,20-tetrakis(4-carbomethoxyphenyl)porphyrin. The longer lifetimes obtained from the increase in the triplet excited state allow for longer exciton diffusion lengths and lower recombination rates in photovoltaics. Also, the enhanced intersystem crossing is beneficial for photodynamic therapy because it increases singlet oxygen generation, which destroys tumor cells. Optimizing photovoltaic performance and PDT efficacy can also be accomplished with donor-acceptor molecules because they have extended electronic pi bond delocalization across the molecule, which causes the molecule to absorb longer wavelengths of light. Donor-acceptor molecules should produce photovoltaic devices that absorb more of the solar spectrum and produce sensitizers that absorb wavelengths of light that can penetrate through tissues. Donor-acceptor molecules were synthesized using 5,15-bis(4-carbomethoxyphenyl)porphyrin as the acceptor and thiazolo[5,4-d]thiazole derivatives as the donor. The excited state dynamics of the heavy atom derivatives and donor-acceptor molecules were studied using UV-vis spectroscopy, steady-state emission, time-resolved and delayed photoluminescence.
A hydrogen maser clock for space - Clocks in future possible and improbable applications

NASA Astrophysics Data System (ADS)

Vessot, Robert F. C.

The development of atomic-H maser clocks for space applications since 1967 is reviewed, with a focus on the 39-kg instrument built for a rocket-flight test of gravitational redshift in 1976. The stability of the oscillator and the instability of earth-space propagation in that test are described, and techniques for overcoming the latter effects are considered. More recent maser clocks employ an H sorption manifold rather than heavy ion pumps; their application to precise satellite position determination for space-based VLBI astronomy is discussed in detail. Extensive diagrams, drawings, and photographs are provided.
Hyperfine Structure and Abundances of Heavy Elements in 68 Tauri (HD 27962)

NASA Astrophysics Data System (ADS)

Martinet, S.; Monier, R.

2017-12-01

HD 27962, also known as 68 Tauri, is a Chemically Peculiar Am star member of the Hyades Open Cluster in the local arm of the Galaxy. We have modeled the high resolution SOPHIE (R=75000) spectrum of 68 Tauri using updated model atmosphere and spectrum synthesis to derive chemical abundances in its atmosphere. In particular, we have studied the effect of the inclusion of Hyperfine Structure of various Baryum isotopes on the determination of the Baryum abundance in 68 Tauri. We have also derived new abundances using updated accurate atomic parameters retrieved from the NIST database.
Adsorption of lead over Graphite Oxide

PubMed Central

Olanipekun, Opeyemi; Oyefusi, Adebola; Neelgund, Gururaj M.; Oki, Aderemi

2014-01-01

The adsorption efficiency and kinetics of removal of lead in presence of graphite oxide (GO) was determined using the Atomic Absorption spectrophotometer (AAS). The GO was prepared by the chemical oxidation of graphite and characterized using FTIR, SEM, TGA and XRD. The adsorption efficiency of GO for the solution containing 50, 100 and 150 ppm of Pb2+ was found to be 98, 91 and 71% respectively. The adsorption ability of GO was found to be higher than graphite. Therefore, the oxidation of activated carbon in removal of heavy metals may be a viable option to reduce pollution in portable water. PMID:24152870
V L Ginzburg and the Atomic Project

NASA Astrophysics Data System (ADS)

Ritus, V. I.

2017-04-01

This paper is an expanded version of the author's talk presented at a session of the Physical Sciences Division of the Russian Academy of Sciences celebrating the 100th anniversary of V L Ginzburg's birth. Tamm's Special group was organized in June 1948 with the task to clarify the feasibility of constructing a hydrogen bomb. Having verified and confirmed the calculated results by Ya B Zel'dovich's group, the Tamm group proposed an original hydrogen bomb design, which, following A D Sakharov's idea, consisted of an atomic bomb surrounded spherically by nested uranium and heavy water layers: the heavy water, on V L Ginzburg's suggestion, was replaced by higher-calorie solid lithium-6 deuteride. The ionization implosion of deuterium by uranium, both heated by the atomic bomb's explosion, greatly accelerates nuclear reactions in deuterium and uranium and increases the total energy release. Upon their approval by the KB-11 top researchers, the Atomic project leadership, and the government, the proposals were implemented in the RDS-6s bomb, which was successfully tested on 12 August 1953. Lithium-6 deuteride turned out to be a convenient multipurpose nuclear fuel. The paper highlights the recognition by the leaders of the country and of the Atomic project that fundamental science plays a crucial role in promoting scientists' ideas and proposals.
Carbon dioxide in the atmosphere: isotopic exchange with ozone and its use as a tracer in the middle atmosphere

NASA Technical Reports Server (NTRS)

Yung, Y. L.; Lee, A. Y.; Irion, F. W.; DeMore, W. B.; Wen, J.

1997-01-01

Atmospheric heavy ozone is enriched in the isotopes 18O and 17O. The magnitude of this enhancement, of the order of 100%, is very large compared with that commonly known in atmospheric chemistry and geochemistry. The heavy oxygen atom in heavy ozone is therefore useful as a tracer of chemical species and pathways that involve ozone or its derived products. As a test of the isotopic exchange reactions, we successfully carry out a series of numerical experiments to simulate the results of the laboratory experiments performed by Wen and Thiemens [1993] on ozone and CO2. A small discrepancy between the experimental and the model values for 17O exchange is also revealed. The results are used to compute the magnitude of isotopic exchange between ozone and carbon dioxide via the excited atom O(1D) in the middle atmosphere. The model for 18O is in good agreement with the observed values.
A MATLAB-based finite-element visualization of quantum reactive scattering. I. Collinear atom-diatom reactions

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

Warehime, Mick; Alexander, Millard H., E-mail: mha@umd.edu

We restate the application of the finite element method to collinear triatomic reactive scattering dynamics with a novel treatment of the scattering boundary conditions. The method provides directly the reactive scattering wave function and, subsequently, the probability current density field. Visualizing these quantities provides additional insight into the quantum dynamics of simple chemical reactions beyond simplistic one-dimensional models. Application is made here to a symmetric reaction (H+H{sub 2}), a heavy-light-light reaction (F+H{sub 2}), and a heavy-light-heavy reaction (F+HCl). To accompany this article, we have written a MATLAB code which is fast, simple enough to be accessible to a wide audience,more » as well as generally applicable to any problem that can be mapped onto a collinear atom-diatom reaction. The code and user's manual are available for download from http://www2.chem.umd.edu/groups/alexander/FEM.« less
Removal of a hazardous heavy metal from aqueous solution using functionalized graphene and boron nitride nanosheets: Insights from simulations.

PubMed

Azamat, Jafar; Sattary, Batoul Shirforush; Khataee, Alireza; Joo, Sang Woo

2015-09-01

A computer simulation was performed to investigate the removal of Zn(2+) as a heavy metal from aqueous solution using the functionalized pore of a graphene nanosheet and boron nitride nanosheet (BNNS). The simulated systems were comprised of a graphene nanosheet or BNNS with a functionalized pore containing an aqueous ionic solution of zinc chloride. In order to remove heavy metal from an aqueous solution using the functionalized pore of a graphene nanosheet and BNNS, an external voltage was applied along the z-axis of the simulated box. For the selective removal of zinc ions, the pores of graphene and BNNS were functionalized by passivating each atom at the pore edge with appropriate atoms. For complete analysis systems, we calculated the potential of the mean force of ions, the radial distribution function of ion-water, the residence time of ions, the hydrogen bond, and the autocorrelation function of the hydrogen bond. Copyright © 2015 Elsevier Inc. All rights reserved.
Kankan diamonds (Guinea) III: δ13C and nitrogen characteristics of deep diamonds

NASA Astrophysics Data System (ADS)

Stachel, T.; Harris, J. W.; Aulbach, S.; Deines, P.

Diamonds from the Kankan area in Guinea formed over a large depth profile beginning within the cratonic mantle lithosphere and extending through the asthenosphere and transition zone into the lower mantle. The carbon isotopic composition, the concentration of nitrogen impurities and the nitrogen aggregation level of diamonds representing this entire depth range have been determined. Peridotitic and eclogitic diamonds of lithospheric origin from Kankan have carbon isotopic compositions (δ13C: peridotitic -5.4 to -2.2‰ eclogitic -19.7 to -0.7‰) and nitrogen characteristics (N: peridotitic 17-648 atomic ppm; eclogitic 0-1,313 atomic ppm; aggregation from IaA to IaB) which are generally typical for diamonds of these two suites worldwide. Geothermobarometry of peridotitic and eclogitic inclusion parageneses (worldwide sources) indicates that both suites formed under very similar conditions within the cratonic lithosphere, which is not consistent with a derivation of diamonds with light carbon isotopic composition from subducted organic matter within subducting oceanic slabs. Diamonds containing majorite garnet inclusions fall to the isotopically heavy side (δ13C: -3.1‰ to +0.9‰) of the worldwide diamond population. Nitrogen contents are low (0-126 atomic ppm) and one of the two nitrogen-bearing diamonds shows such a low level of nitrogen aggregation (30% B-centre) that it cannot have been exposed to ambient temperatures of the transition zone (>=1,400 °C) for more than 0.2 Ma. This suggests rapid upward transport and formation of some Kankan diamonds pene-contemporaneous to Cretaceous kimberlite activity. Similar to these diamonds from the asthenosphere and the transition zone, lower mantle diamonds show a small shift towards isotopic heavy compositions (-6.6 to -0.5‰, mode at -3.5‰). As already observed for other mines, the nitrogen contents of lower mantle diamonds were below detection (using FTIRS). The mutual shift of sublithospheric diamonds towards isotopic heavier compositions suggests a common carbon source, which may have inherited an isotopic heavy composition from a component consisting of subducted carbonates.
Kankan diamonds (Guinea) III: δ13C and nitrogen characteristics of deep diamonds

NASA Astrophysics Data System (ADS)

Stachel, T.; Harris, J. W.; Aulbach, S.; Deines, P.

2001-08-01

Diamonds from the Kankan area in Guinea formed over a large depth profile beginning within the cratonic mantle lithosphere and extending through the asthenosphere and transition zone into the lower mantle. The carbon isotopic composition, the concentration of nitrogen impurities and the nitrogen aggregation level of diamonds representing this entire depth range have been determined. Peridotitic and eclogitic diamonds of lithospheric origin from Kankan have carbon isotopic compositions (δ13C: peridotitic -5.4 to -2.2‰ eclogitic -19.7 to -0.7‰) and nitrogen characteristics (N: peridotitic 17-648 atomic ppm; eclogitic 0-1,313 atomic ppm; aggregation from IaA to IaB) which are generally typical for diamonds of these two suites worldwide. Geothermobarometry of peridotitic and eclogitic inclusion parageneses (worldwide sources) indicates that both suites formed under very similar conditions within the cratonic lithosphere, which is not consistent with a derivation of diamonds with light carbon isotopic composition from subducted organic matter within subducting oceanic slabs. Diamonds containing majorite garnet inclusions fall to the isotopically heavy side (δ13C: -3.1‰ to +0.9‰) of the worldwide diamond population. Nitrogen contents are low (0-126 atomic ppm) and one of the two nitrogen-bearing diamonds shows such a low level of nitrogen aggregation (30% B-centre) that it cannot have been exposed to ambient temperatures of the transition zone (>=1,400 °C) for more than 0.2 Ma. This suggests rapid upward transport and formation of some Kankan diamonds pene-contemporaneous to Cretaceous kimberlite activity. Similar to these diamonds from the asthenosphere and the transition zone, lower mantle diamonds show a small shift towards isotopic heavy compositions (-6.6 to -0.5‰, mode at -3.5‰). As already observed for other mines, the nitrogen contents of lower mantle diamonds were below detection (using FTIRS). The mutual shift of sublithospheric diamonds towards isotopic heavier compositions suggests a common carbon source, which may have inherited an isotopic heavy composition from a component consisting of subducted carbonates.
Native flexibility of structurally homologous proteins: insights from anisotropic network model.

PubMed

Sarkar, Ranja

2017-01-01

Single-molecule microscopic experiments can measure the mechanical response of proteins to pulling forces applied externally along different directions (inducing different residue pairs in the proteins by uniaxial tension). This response to external forces away from equilibrium should in principle, correlate with the flexibility or stiffness of proteins in their folded states. Here, a simple topology-based atomistic anisotropic network model (ANM) is shown which captures the protein flexibility as a fundamental property that determines the collective dynamics and hence, the protein conformations in native state. An all-atom ANM is used to define two measures of protein flexibility in the native state. One measure quantifies overall stiffness of the protein and the other one quantifies protein stiffness along a particular direction which is effectively the mechanical resistance of the protein towards external pulling force exerted along that direction. These measures are sensitive to the protein sequence and yields reliable values through computations of normal modes of the protein. ANM at an atomistic level (heavy atoms) explains the experimental (atomic force microscopy) observations viz., different mechanical stability of structurally similar but sequentially distinct proteins which, otherwise were implied to possess similar mechanical properties from analytical/theoretical coarse-grained (backbone only) models. The results are exclusively demonstrated for human fibronectin (FN) protein domains. The topology of interatomic contacts in the folded states of proteins essentially determines the native flexibility. The mechanical differences of topologically similar proteins are captured from a high-resolution (atomic level) ANM at a low computational cost. The relative trend in flexibility of such proteins is reflected in their stability differences that they exhibit while unfolding in atomic force microscopic (AFM) experiments.
Accessibility of selenomethionine proteins by total chemical synthesis: structural studies of human herpesvirus-8 MIP-II.

PubMed

Shao, W; Fernandez, E; Wilken, J; Thompson, D A; Siani, M A; West, J; Lolis, E; Schweitzer, B I

1998-12-11

The determination of high resolution three-dimensional structures by X-ray crystallography or nuclear magnetic resonance (NMR) is a time-consuming process. Here we describe an approach to circumvent the cloning and expression of a recombinant protein as well as screening for heavy atom derivatives. The selenomethionine-modified chemokine macrophage inflammatory protein-II (MIP-II) from human herpesvirus-8 has been produced by total chemical synthesis, crystallized, and characterized by NMR. The protein has a secondary structure typical of other chemokines and forms a monomer in solution. These results indicate that total chemical synthesis can be used to accelerate the determination of three-dimensional structures of new proteins identified in genome programs.
The interstellar abundances of tin and four other heavy elements

NASA Technical Reports Server (NTRS)

Hobbs, L. M.; Welty, D. E.; Morton, D. C.; Spitzer, L.; York, D. G.

1993-01-01

Spectra recorded at 1150-1600 A with an instrumental resolution near 16 km/s were obtained with the Goddard High-Resolution Spectrograph on board the HST. The gaseous interstellar abundances of five heavy elements along the light paths to 23 Ori, 15 Mon, 1 Sco, Pi Sco, and Pi Aqr were determined from the observations. The 1400.450 A line of Sn II was detected and identified toward three stars; at Z = 50, tin is the first element from the fifth row of the periodic table to be identified in the interstellar medium. One spectral line of each of Cu II (Z = 29) and Ga II (Z = 31), three lines of Ge II (Z = 32), and two lines of Kr I (Z = 36) were also detected toward some or all of the five stars. The depletions of these five heavy elements generally decrease monotonically with increasing atomic number toward each of the six stars, and tin is generally undepleted within the observational errors. The depletions of 26 elements from the interstellar gas in an average dense interstellar cloud appear to correlate with the elemental 'nebular' condensation temperatures more closely than with the first ionization potentials.

Matrix photochemistry of small molecules: Influencing reaction dynamics on electronically excited hypersurfaces

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

Laursen, S.L.

Investigations of chemical reactions on electronically excited reaction surfaces are presented. The role of excited-surface multiplicity is of particular interest, as are chemical reactivity and energy transfer in systems in which photochemistry is initiated through a metal atom sensitizer.'' Two approaches are employed: A heavy-atom matrix affords access to forbidden triplet reaction surfaces, eliminating the need for a potentially reactive sensitizer. Later, the role of the metal atom in the photosensitization process is examined directly.
Nuclear chemistry. Annual report, 1974

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

Conzett, H.E.; Edelstein, N.M.; Tsang, C.F.

1975-07-01

The 1974 Nuclear Chemistry Annual Report contains information on research in the following areas: nuclear science (nuclear spectroscopy and radioactivity, nuclear reactions and scattering, nuclear theory); chemical and atomic physics (heavy ion-induced atomic reactions, atomic and molecular spectroscopy, photoelectron spectroscopy and hyperfine interactions); physical, inorganic, and analytical chemistry (x-ray crystallography, physical and inorganic chemistry, geochemistry); and instrumentation. Thesis abstracts, 1974 publication titles, and an author index are also included. Papers having a significant amount of information are listed separately by title. (RWR)
Heavy Atom Vibrational Modes and Low-Energy Vibrational Autodetachment in Nitromethane Anions

NASA Astrophysics Data System (ADS)

Thompson, Michael C.; Baraban, Joshua H.; Stanton, John F.; Weber, J. Mathias

2015-06-01

We use Ar predissociation and vibrational autodetachment below 2100 wn to obtain vibrational spectra of the low-energy modes of nitromethane anion. We interpret the spectra using anharmonic calculations, which reveal strong mode coupling and Fermi resonances. Not surprisingly, the number of evaporated Ar atoms varies with photon energy, and we follow the propensity of evaporating two versus one Ar atoms as photon energy increases. The photodetachment spectrum is discussed in the context of threshold effects and the importance of hot bands.
Preliminary zoning for risk assessment and remediation purposes in Portman Bay.

NASA Astrophysics Data System (ADS)

Pérez-Sirvent, Carmen; Martínez-Sanchez, MJose; Garcia-Lorenzo, MariLuz; Hernandez-Cordoba, Manuel; Molina, Jose; Gonzalez, Eva; Perez-Espinosa, Victor

2014-05-01

Portman bay is a singular point of mining impact in the Mediterranean area. The site is located in the province of Murcia, south-eastern Spain, and was completely inundated with more than 63 million tonnes of mining waste discharged through a huge washing plant. Wastes from mining activities mainly consisted of ore materials (galena, pyrite and sphalerite), phyllosilicates, in addition to siderite, iron oxides and sometimes alteration products such as jarosite, alunite, kaolinite and greenalite. These materials were submitted to a concentration process by floatation with sea water and as a result of the discharge, the whole of the bay was filled up with wastes which also extended into the Mediterranean Sea. In the last years of activity, wastes were even poured alternatively in the sea or over the sediments filling the bay. These actions have produced a very high heterogeneity in the sediments. Although after the end of the discharges it has been possible to reach a certain degree of balance, the sediments, especially those closest to the sea, are subjected to marine dynamics and the effects of rainfall and runoffs. In 2007, a recuperation pilot project was developed and financed by the Spanish Government. In the first step of this project, the complete physical, chemical and mineralogical characterization of sediments, both in surface and at depth was carried out. Twenty surface samples were collected (<1 m) and twelve sediment cores were also collected at the same time. To determine the total trace element content, zinc and iron levels were determined by flame atomic absorption spectrometry, while lead, cadmium and copper levels were determined by electrothermal atomization atomic absorption spectrometry. The arsenic content was measured by atomic fluorescence spectrometry using an automated continuous flow hydride generation spectrometer. The reliability of the results was verified by analyzing standard reference materials. The mineralogical composition was determined using Cu-Kα radiation with an X-ray Diffractometer and appropriate software. Data for metal leached, Acid-volatile sulphide (AVS) and simultaneously extracted metals (SEM) were also obtained. The results allowed two types of materials to be differentiated. The first one with a fine particle size, is related with the direct discharge of wastes and contains jarosite and other minerals resulting of supergenic alteration. The pH is low and both the level of heavy metals and chemical reactivity are high. The second, different material is black sand, a sediment of coarse texture in which stable minerals, phylosilicates, iron oxides and hydroxides, siderite, pyrite and quartz predominate. The pH is close to neutrality and despite a high heavy metals level, the chemical reactivity is low. The data allowed a preliminary zoning of the risk in the area to be established, and this was the starting point to outline the remediation project.
Aryl nitrene rearrangements: spectroscopic observation of a benzazirine and its ring expansion to a ketenimine by heavy-atom tunneling.

PubMed

Inui, Hiroshi; Sawada, Kazuhiro; Oishi, Shigero; Ushida, Kiminori; McMahon, Robert J

2013-07-17

In the photodecompositions of 4-methoxyphenyl azide (1) and 4-methylthiophenyl azide (5) in argon matrixes at cryogenic temperatures, benzazirine intermediates were identified on the basis of IR spectra. As expected, the benzazirines photochemically rearranged to the corresponding ketenimines and triplet nitrenes. Interestingly, with the methylthio substituent, the rearrangement of benzazirine 8 to ketenimine 7 occurred at 1.49 × 10(-5) s(-1) even in the dark at 10 K, despite a computed activation barrier of 3.4 kcal mol(-1). Because this rate is 10(57) times higher than that calculated for passing over the barrier and because it shows no temperature dependence, the rearrangement mechanism is interpreted in terms of heavy-atom tunneling.
An investigation of one- versus two-dimensional semiclassical transition state theory for H atom abstraction and exchange reactions.

PubMed

Greene, Samuel M; Shan, Xiao; Clary, David C

2016-02-28

We investigate which terms in Reduced-Dimensionality Semiclassical Transition State Theory (RD SCTST) contribute most significantly in rate constant calculations of hydrogen extraction and exchange reactions of hydrocarbons. We also investigate the importance of deep tunneling corrections to the theory. In addition, we introduce a novel formulation of the theory in Jacobi coordinates. For the reactions of H atoms with methane, ethane, and cyclopropane, we find that a one-dimensional (1-D) version of the theory without deep tunneling corrections compares well with 2-D SCTST results and accurate quantum scattering results. For the "heavy-light-heavy" H atom exchange reaction between CH3 and CH4, deep tunneling corrections are needed to yield 1-D results that compare well with 2-D results. The finding that accurate rate constants can be obtained from derivatives of the potential along only one dimension further validates RD SCTST as a computationally efficient yet accurate rate constant theory.
Particulate matter and heavy metal deposition on the leaves of Euonymus japonicus during the East Asian monsoon in Beijing, China

PubMed Central

Hong, Xiuling; Sun, Liwei

2017-01-01

Plants can be effectively used as bio-monitors of environmental pollution. However, how the particulate matter (PM) and heavy metal retention ability of plants changes in different areas with human disturbance along with monsoon has not yet been investigated in urban ecosystems. In this study, we measured the amount of PM and heavy metals such as Ni, Cr, Cu, Pb, and Zn accumulated by the leaves of Euonymus japonicus during the East Asian monsoon from different functional units in Beijing, China. A rinse-and-weigh method developed in our laboratory was used to determine the mass of the PM, and electro-thermal atomic absorption spectrometry was used for heavy metal analysis. We found that the types of functional units had little influence, whereas the monsoon had a significant effect on the deposition of PM: northwest areas during the monsoon had the lowest effect (with 0.005, 0.453, 0.643, and 1.569 g/m2 fine, coarse, large, and total PM, respectively), and the southeast areas during the monsoon had the highest effect (0.015, 2.687, 1.941, and 4.228 g/m2 for fine, coarse, large, and total PM, respectively). Notable, we found considerable variations in heavy metal accumulation across the functional units analyzed, that is, the accumulation level was higher in communities than in parks (P < 0.0001 for all heavy metals). Moreover, a positive relationship was found between PM retention and heavy metal accumulation by the leaves of E. japonicus. Taken together, our results suggested that the PM and heavy metal retention ability of E. japonicus was sensitive to human disturbance and monsoon in Beijing. Since E. japonicus is a widely distributed tree and has the ability of to purify the atmosphere, it is an ideal plant for mitigating urban environmental pollution. PMID:28662081
Impact of reactive oxygen species on antioxidant capacity of male reproductive system.

PubMed

Riaz, Muhammad; Mahmood, Zahed; Shahid, Muhammad; Saeed, M Usman Qamar; Tahir, Imtiaz Mahmood; Shah, Sm Ali; Munir, Naveed; El-Ghorab, Ahmed

2016-09-01

The present research work was aimed to study the mutual interaction of reactive oxygen species (ROS) and basal cells antioxidant capacity in the male reproductive system and to further establish the association between selected heavy metals and stress markers. Total oxidant status (TOS) and total antioxidant status (TAS) of serum and seminal plasma were determined by automated photometric methods. The concentrations of Selenium (Se), Lead (Pb), and Cadmium (Cd) were determined by using atomic absorption spectrophotometer. The TOS was increased significantly (P <0.05) in seminal plasma as well as in the serum of the infertile group when compared with the fertile group. On the other hand, the TAS of the infertile group was found to be noticeably decreased (P <0.05) when compared with the TAS of the fertile group. Among the heavy metals, a noticeably lower concentration of Se was detected in the infertile group whereas markedly elevated levels of Cd and Pb were observed in the infertile group compared with the fertile group. Among the infertile group a significant inverse correlation (r = -0.521, P <0.05) was observed between Se and TOS and between Cd and Pb (r = -0.407, P <0.05). Contrarily among the infertile group a considerable positive relationship was established between Se and TAS (r = 0.507, P <0.05). It was concluded that the oxidant stress reduces the antioxidant activity in infertile men by elevating the production of ROS. A lower concentration of Se and elevated levels of Pb and Cd explain the individual's exposure to these heavy metals. The study also revealed that the heavy metal toxicity contributes significantly to male infertility. © The Author(s) 2015.
Complexation of Uranium by Cells and S-Layer Sheets of Bacillus sphaericus JG-A12

PubMed Central

Merroun, Mohamed L.; Raff, Johannes; Rossberg, André; Hennig, Christoph; Reich, Tobias; Selenska-Pobell, Sonja

2005-01-01

Bacillus sphaericus JG-A12 is a natural isolate recovered from a uranium mining waste pile near the town of Johanngeorgenstadt in Saxony, Germany. The cells of this strain are enveloped by a highly ordered crystalline proteinaceous surface layer (S-layer) possessing an ability to bind uranium and other heavy metals. Purified and recrystallized S-layer proteins were shown to be phosphorylated by phosphoprotein-specific staining, inductive coupled plasma mass spectrometry analysis, and a colorimetric method. We used extended X-ray absorption fine-structure (EXAFS) spectroscopy to determine the structural parameters of the uranium complexes formed by purified and recrystallized S-layer sheets of B. sphaericus JG-A12. In addition, we investigated the complexation of uranium by the vegetative bacterial cells. The EXAFS analysis demonstrated that in all samples studied, the U(VI) is coordinated to carboxyl groups in a bidentate fashion with an average distance between the U atom and the C atom of 2.88 ± 0.02 Å and to phosphate groups in a monodentate fashion with an average distance between the U atom and the P atom of 3.62 ± 0.02 Å. Transmission electron microscopy showed that the uranium accumulated by the cells of this strain is located in dense deposits at the cell surface. PMID:16151146
[Exposure to metal compounds in occupational galvanic processes].

PubMed

Surgiewicz, Jolanta; Domański, Wojciech

2006-01-01

Occupational galvanic processes are provided in more than 600 small and medium enterprises in Poland. Workers who deal with galvanic coating are exposed to heavy metal compounds: tin, silver, copper and zinc. Some of them are carcinogenic, for example, hexavalent chromium compounds, nickel and cadmium compounds. Research covered several tens of workstations involved in chrome, nickel, zinc, tin, silver, copper and cadmium plating. Compounds of metals present in the air were determined: Cr, Ni, Cd, Sn, Ag--by atomic absorption spectrometry with electrothermal atomization (ET-AAS) and Zn--by atomic absorption spectrometry with flame atomization (F-AAS). The biggest metal concentrations--of silver and copper--were found at workstations of copper, brass, cadmium, nickel and chrome plating, conducted at the same time. Significant concentrations of copper were found at workstations of maintenance bathing and neutralizing of sewage. The concentrations of metals did not exceed Polish MAC values. MAC values were not exceeded for carcinogenic chromium(VI), nickel or cadmium, either. In galvanic processes there was no hazard related to single metals or their compounds, even carcinogenic ones. Combined exposure indicators for metals at each workstation did not exceed 1, either. However, if there are even small quantities of carcinogenic agents, health results should always be taken into consideration.
Actinide targets for the synthesis of super-heavy elements

DOE PAGES

Roberto, J.; Alexander, Charles W.; Boll, Rose Ann; ...

2015-06-18

Since 2000, six new super-heavy elements with atomic numbers 113 through 118 have been synthesized in hot fusion reactions of 48Ca beams on actinide targets. These target materials, including 242Pu, 244Pu, 243Am, 245Cm, 248Cm, 249Cf, and 249Bk, are available in very limited quantities and require specialized production and processing facilities resident in only a few research centers worldwide. This report describes the production and chemical processing of heavy actinide materials for super-heavy element research, current availabilities of these materials, and related target fabrication techniques. The impact of actinide materials in super-heavy element discovery is reviewed, and strategies for enhancing themore » production of rare actinides including 249Bk, 251Cf, and 254Es are described.« less
PREPARATION OF OXALATES OF METALS OF ATOMIC NUMBER GREATER THAN 88

DOEpatents

Duffield, R.B.

1959-02-01

A method is presented for the preparation of oxalates of metals of atomic number greater than 88. A solid peroxide of the heavy metal is contacted with an aqueous oxalic acid solution ai a temperature of about 50 C for a period of time sufficient to form the insoluble metal oxalate which is subsequentiy recovered as a pures crystalline compound.
Magnitude of finite-nucleus-size effects in relativistic density functional computations of indirect NMR nuclear spin-spin coupling constants.

PubMed

Autschbach, Jochen

2009-09-14

A spherical Gaussian nuclear charge distribution model has been implemented for spin-free (scalar) and two-component (spin-orbit) relativistic density functional calculations of indirect NMR nuclear spin-spin coupling (J-coupling) constants. The finite nuclear volume effects on the hyperfine integrals are quite pronounced and as a consequence they noticeably alter coupling constants involving heavy NMR nuclei such as W, Pt, Hg, Tl, and Pb. Typically, the isotropic J-couplings are reduced in magnitude by about 10 to 15 % for couplings between one of the heaviest NMR nuclei and a light atomic ligand, and even more so for couplings between two heavy atoms. For a subset of the systems studied, viz. the Hg atom, Hg(2) (2+), and Tl--X where X=Br, I, the basis set convergence of the hyperfine integrals and the coupling constants was monitored. For the Hg atom, numerical and basis set calculations of the electron density and the 1s and 6s orbital hyperfine integrals are directly compared. The coupling anisotropies of TlBr and TlI increase by about 2 % due to finite-nucleus effects.
Evaluation of Heavy Metal Exposure to Soil and Paddy Plant around the Closed Municipal Solid Waste Landfill: Case Study at Gunung Tugel Landfill, Banyumas-Central Java

NASA Astrophysics Data System (ADS)

Kasam; Rahmawati, Suphia; Mulya Iresha, Fajri; Wacano, Dhandhun; Farida Fauziah, Ida; Afif Amrullah, Muhammad

2018-01-01

This work was focused on assessing the exposure of heavy metal from closed municipal solid waste (MSW) landfill on soil and paddy plants. This study aimed to determine heavy metal content whether at the soil in the around Gunung Tugel landfill included and accumulated in the paddy plant tissues. The investigated metals include chromium (Cr), copper (Cu), cadmium (Cd), iron (Fe), and zinc (Zn). The samples were acid-digested before the desired elements were measured using Atomic Absorption Spectrophotometry (AAS). The results are presented as distribution map of the landfill area based on the total heavy metals content distribution in the soil and paddy plants. The samples shown that the concentrations of heavy metals around Gunung Tugel landfill are 6.27-34.71 mg/kg, 0.17-0.42 mg/kg, 28.29-48.69 mg/kg, 18,997.26-32,572.29 mg/kg, 342.74-834.49 mg/kg, 136.10-290.14 mg/kg at the top soil and 0.00-1.70 mg/kg, 0.00-0.26 mg/kg, 0.79-10.46 mg/kg, 13.88-61.46 mg/kg, 18.79-50.56 mg/kg, 87.27-273.22 mg/kg at the paddy for Cr, Cd, Cu, Fe, Mn, and Zn respectively. According to the results, The Gunung Tugel landfill is not a direct source of heavy metal pollution at paddy plant in the landfill area, but through surface water and soil media. Rainfall around landfill is quite high ie more 2000 mm/year of rainfall and soil permeability is 1.0 cm/sec.
Influence of voltage input to heavy metal removal from electroplating wastewater using electrocoagulation process

NASA Astrophysics Data System (ADS)

Wulan, D. R.; Cahyaningsih, S.; Djaenudin

2017-03-01

In medium capacity, electroplating industry usually treats wastewater until 5 m3 per day. Heavy metal content becomes concern that should be reduced. Previous studies performed electrocoagulation method on laboratory scale, either batch or continuous. This study was aimed to compare the influence of voltage input variation into heavy metal removal in electroplating wastewater treatment using electrocoagulation process on laboratory-scale in order to determine the optimum condition for scaling up the reactor into pilot-scale. The laboratory study was performed in 1.5 L glass reactor in batch system using wastewater from electroplating industry, the voltage input varied at 20, 30 and 40 volt. The electrode consisted of aluminium 32 cm2 as sacrifice anode and copper 32 cm2 as cathode. During 120 min electrocoagulation process, the pH value was measured using pH meter, whereas the heavy metal of chromium, copper, iron, and zinc concentration were analysed using Atomic Absorption Spectrophotometer (AAS). Result showed that removal of heavy metals from wastewater increased due to the increasing of voltage input. Different initial concentration of heavy metals on wastewater, resulted the different detention time. At pilot-scale reactor with 30 V voltage input, chromium, iron, and zinc reached removal efficiency until 89-98%, when copper reached 79% efficiency. At 40V, removal efficiencies increased on same detention time, i.e. chromium, iron, and zinc reached 89-99%, whereas copper reached 85%. These removal efficiencies have complied the government standard except for copper that had higher initial concentration in wastewater. Kinetic rate also calculated in this study as the basic factor for scaling up the process.
Persistent sample circulation microextraction combined with graphite furnace atomic absorption spectroscopy for trace determination of heavy metals in fish species marketed in Kermanshah, Iran, and human health risk assessment.

PubMed

Safari, Yahya; Karimaei, Mostafa; Sharafi, Kiomars; Arfaeinia, Hossein; Moradi, Masoud; Fattahi, Nazir

2018-06-01

Persistent sample circulation microextraction (PSCME) combined with graphite furnace atomic absorption spectrometry (GFAAS) was developed as a high pre-concentration technique for the determination of heavy metals in fish species. In this method, a few microliters of organic solvent (40.0 µL carbon tetrachloride) was transferred to the bottom of a conical sample cup. Then 10.0 mL of aqueous solution was transformed to fine droplets while passing through the organic solvent. At this stage, metal-ligand hydrophobic complex was extracted into the organic solvent. After extraction, 20 µL of extraction solvent was injected into the graphite tube using an auto-sampler. Under optimal conditions, enrichment factors and enhancement factor were in the range of 180-240 and 155-214, respectively. The calibration curves were linear in the range of 0.03-200 µg kg -1 and the limits of detection (LODs) were in the range of 0.01-0.05 µg kg -1 . Repeatability (intra-day) and reproducibility (inter-day) for 0.50 µg L -1 Hg and 0.10 µg L -1 Cd and Pb were in the range of 3.1-4.2% (n = 7) and 4.3-6.1% (n = 7), respectively. Potential human health risk assessment was conducted by calculating estimated weekly intake (EWI) of the metals from eating fish and comparison of these values with provisional tolerable weekly intake (PTWI) values. EWI data for the studied metals through fish consumption were lower than the PTWI values. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.
Impact of breeding region and season on the content of some trace elements and heavy metals in the hair of cows.

PubMed

Cygan-Szczegielniak, Dorota; Stanek, Magdalena; Giernatowska, Emilia; Janicki, Bogdan

2014-01-01

The aim of the research was to determine the effect of the season and the breeding region on the content of selected minerals (Zn, Cu, Mn, Fe, Pb, Cd) in the hair of dairy cows. The research material covered 114 Holstein-Friesian breed cows from three breeding centres in Poland, hereafterreferred to as A, B and C. Breeding centre A is located in Opolskie province, breeding centre B in Podlaskie province and breeding centre C in Kujawsko-Pomorskie province. The cows were kept in freestanding cowsheds with den boxes. Animal nutrition involved the use of the TMR system, considering division into nutrition groups. Hair was sampled in summer and in the period of winter and spring from the side of the body, directly behind the coastal arch. The Zn, Cu, Mn, Fe analysis was performed with atomic absorption spectrometry. The Pb and Cd content was assayed with the use of the electrothermal atomic absorption spectrometry. The results demonstrated the effect of season and breeding region on the level of the minerals and heavy metals assayed in the hair of cows being in the period of drying-off. The hair sampled in winter from cows from C demonstrated a higher concentration of most elements except for Fe than in material derived in summer. Hair sampled in winter from cows from the B centre showed higher Zn, Cu and Pb concentrations as compared with summer. Higher Cu, Mn, Fe and Pb concentrations were determined in hair sampled during winter from cows from A than in the material obtained in summer. The Cd content in the cow hair did not exceed the admissible norm, however, normal levels were exceeded for Pb in hair sampled in winter from cows from breeding centre C.
Analysis of several heavy metals in wild edible mushrooms from regions of China.

PubMed

Chen, Xin-Hua; Zhou, Hong-Bo; Qiu, Guan-Zhou

2009-08-01

The metal (Cu, Ni, Cd, Hg, As, Pb) contents in wild edible mushrooms collected from three different sites in China were determined by atomic absorption spectrometry and atomic fluorescence spectrometry. All element concentrations were determined on a dry weight basis. A total of 11 species was studied, five being from the urban area and six from rural areas in China. The As content ranged from 0.44 to 1.48 mg/kg. The highest As content was seen in Macrolepiota crustosa from the urban area, and the lowest in Russula virescens from rural areas. A high Ni concentration (1.35 mg/kg) was found in Calvatia craniiformis from the urban area. The lowest Ni level was 0.11 mg/kg, for the species R. virescens and Cantharellus cibarius. The Cu content ranged from 39.0 to 181.5 mg/kg. The highest Cu content was seen in Agaricus silvaticus and the lowest in C. cibarius. The Pb content ranged from 1.9 to 10.8 mg/kg. The highest Pb value was found in C. craniiformis. The Cd content ranged from 0.4 to 91.8 mg/kg. The highest Cd value was found in M. crustosa. The Hg content ranged from 0.28 to 3.92 mg/kg. The highest Hg level was found in Agaricus species. The levels of the heavy metals Cd, Pb, and Hg in the studied mushroom species from urban area can be considered high. The metal-to-metal correlation analysis supported they were the same source of contamination. High automobile traffic was identified as the most likely source of the contamination. Based upon the present safety standards, consumption of those mushrooms that grow in the polluted urban area should be avoided.
Content of Cr, Cu, Pb, and Zn on Pacific white shrimp cultured in modern farm at BLUPPB, Karawang, West Java

NASA Astrophysics Data System (ADS)

Takarina, N. D.; Rahman, A.; Siswanting, T.; Pin, T. J.

2018-03-01

Heavy metal is one of the hazardous substances which often found in shrimp farm. Since this shrimp become mostly favorable food, it is necessary to determine the content of metal in this shrimps. This research was aimed to determine the content of Cr, Cu, Pb, and Zn on Pacific white shrimp cultured on the modern farm at BLUPPB, Karawang, West Java. Samples were taken from five farms. During transport, samples were kept in a more relaxed box. Farms used were designed using black plastic as the bottom layer to separate contact with soil. Heavy metal of Cr, Cu, Pb, and Zn on shrimp meat was analyzed using Atomic Absorption Spectrophotometry method. The content of Cr was ranged from 0.06 – 0.38 ppm and Pb were 0.02 – 0.05 ppm. The content of Cu was ranged from 1.89 – 15.25 ppm and Zn were 2.16 – 3.92 ppm. According to government rules and literature, those content were below a threshold which was 0.4 ppm for Cu, 0.5 ppm for Pb, 20 ppm for Cu and 0.2 ppm for Zn.
Cell inactivation, repair and mutation induction in bacteria after heavy ion exposure: results from experiments at accelerators and in space.

PubMed

Horneck, G; Schafer, M; Baltschukat, K; Weisbrod, U; Micke, U; Facius, R; Bucker, H

1989-01-01

To understand the mechanisms of accelerated heavy ions on biological matter, the responses of spores of B. subtilis to this structured high LET radiation was investigated applying two different approaches. 1) By the use of the Biostack concept, the inactivation probability as a function of radial distance to single particles' trajectory (i.e. impact parameter) was determined in space experiments as well as at accelerators using low fluences of heavy ions. It was found that spores can survive even a central hit and that the effective range of inactivation extends far beyond impact parameters where inactivation by delta-ray dose would be effective. Concerning the space experiment, the inactivation cross section exceeds those from comparable accelerator experiments by roughly a factor of 20. 2) From fluence effect curves, cross sections for inactivation and mutation induction, and the efficiency of repair processes were determined. They are influenced by the ions characteristics in a complex manner. According to dependence on LET, at least 3 LET ranges can be differentiated: A low LET range (app. < 200 keV/micrometers), where cross sections for inactivation and mutation induction follow a common curve for different ions and where repair processes are effective; an intermediate LET range of the so-called saturation cross section with negligible mutagenic and repair efficiency; and a high LET range (>1000 keV/micrometers) where the biological endpoints are majorly dependent on atomic mass and energy of the ion under consideration.

Heavy metal accumulation in leaves and beans of cacao (Theobroma cacao L.) in major cacao growing regions in Peru.

PubMed

Arévalo-Gardini, Enrique; Arévalo-Hernández, Cesar O; Baligar, Virupax C; He, Zhenli L

2017-12-15

Peru is one of the leading exporters of organic cacao beans in the world. However, the accumulation of heavy metals in cacao beans represents a problem for cocoa bean export and chocolate quality. The aim of this study was to investigate the distribution and accumulation of heavy metals in cacao leaves and cocoa beans in three major cacao growing regions of Peru. The study was conducted in cacao plantations of 10 to 15years old in three regions of Peru: North (Regions of Tumbes, Piura, Cajamarca, and Amazonas); Center (Regions of Huánuco and San Martin) and South (Junin and Cuzco). Samples of leaf and cacao beans were collected from 70 cacao plantations, and the nature of cacao clone or genotype sampled was recorded. The concentrations of heavy metals such as Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn in leaves and beans were determined using atomic absorption spectrophotometer. Overall, concentrations of heavy metals were below the critical limits; however, the presence of high levels of Cd in cacao grown in Amazonas, Piura, and Tumbes regions is of primary concern. Plantations of cacao with different cacao clones show differences in Cd accumulation both in leaves and cocoa beans. Therefore, it is promising to screen low Cd accumulator cacao genotypes for safe production of cacao on lightly to moderately Cd contaminated soils. Also, synergism between Zn and Cd present both in plant and soil suggests that Zn has a direct effect on Cd accumulation in cacao. Copyright © 2017 Elsevier B.V. All rights reserved.
Heavy metals in fish from the Red Sea, Arabian Sea, and Indian Ocean: effect of origin, fish species and size and correlation among the metals.

PubMed

Obaidat, Mohammad M; Massadeh, Adnan M; Al-Athamneh, Ahmad M; Jaradat, Qasem M

2015-04-01

This study determined the levels of As, Cu, Pb, and Cd in fish from Red Sea, Arabian Sea, and Indian Ocean by graphite furnace atomic absorption spectrophotometry. Metal levels were compared with international standards. The levels among fish types and origin, the relationship among metals, and the correlation between the levels and fish size were statistically tested. Fish type and origin significantly affected the levels. None of the fish contained As, Cu, and Pb above the FAO and EU codes. However, Cd exceeded the Jordanian, FAO, and EC codes from the three origins. As and Cd positively correlated with each other in Arabian Sea fish. As and Pb correlated negatively, but Cu and Cd did not correlate with fish size. This study indicates that Cd is common in fish from the three origins regardless the fish size. This warrants continuous monitoring for heavy metals, especially Cd, in internationally traded fish.
Improving isotopic identification with INDRA Silicon-CsI(Tl) telescopes

NASA Astrophysics Data System (ADS)

Lopez, O.; Pârlog, M.; Borderie, B.; Rivet, M. F.; Lehaut, G.; Tabacaru, G.; Tassan-Got, L.; Pawłowski, P.; Bonnet, E.; Bougault, R.; Chbihi, A.; Dell'Aquila, D.; Frankland, J. D.; Galichet, E.; Gruyer, D.; La Commara, M.; Le Neindre, N.; Lombardo, I.; Manduci, L.; Marini, P.; Steckmeyer, J. C.; Verde, G.; Vient, E.; Wieleczko, J. P.; Indra Collaboration

2018-03-01

Profiting from previous works done with the INDRA multidetector on the description of the light response L of the CsI(Tl) crystals to different impinging nuclei, we propose an improved ΔE - L identification-calibration procedure for Silicon-Caesium Iodide (Si-CsI) telescopes, namely an Advanced Mass Estimate (AME) method. AME is compared to the usual, simple visual analysis of the corresponding two-dimensional map of ΔE - E type, by using INDRA experimental data from nuclear reactions induced by heavy ions in the Fermi energy regime. We show that the capability of such telescopes to identify both the atomic Z and the mass A numbers of light and heavy reaction products, can be quantitatively improved thanks to the proposed approach. This conclusion opens new possibilities to use INDRA for studying these reactions especially with radioactive beams. Indeed, the determination of the mass for charged reaction products becomes of paramount importance to shed light on the role of the isospin degree of freedom in the nuclear equation of state [1,2].
Essential and toxic elements in honeys from a region of central Italy.

PubMed

Meli, M A; Desideri, D; Roselli, C; Benedetti, C; Feduzi, L

2015-01-01

Levels of iron (Fe), manganese (Mn), chromium (Cr), copper (Cu), zinc (Zn), mercury (Hg), cadmium (Cd), and lead (Pb) in several types of honey produced in a region of Central Italy were determined by atomic absorption spectroscopy (AAS). The degree of humidity, sugar content, pH, free acidity, combined acidity (lactones), and total acidity were also measured. These elements were found to be present in honey in various proportions depending upon (1) the area foraged by bees, (2) flower type visited for collection of nectar, and (3) quality of water in the vicinity of the hive. Strong positive correlations occurred between Pb and Hg, Pb and Cd, Pb and Fe, Pb and Cr, Hg and Cd, and Hg and Fe. The honey products synthesized in Central Italy were of good quality, but not completely free of heavy metal contamination. Compared with established recommended daily intakes, heavy metals or trace element intoxication following honey consumption in Italy was found not to be a concern for human health.
Particle track identification: application of a new technique to apollo helmets.

PubMed

Fleischer, R L; Hart, H R; Giard, W R

1970-12-11

The Apollo helmets are being used to record the dose of heavy particles to which astronauts are exposed on space missions. An improved method for examining and identifying the etched tracks of heavy charged particles consists of replicating tracks and measuring the etching rate as a function of position along the track. Tracks have been observed in Apollo helmets that correspond to ionized atoms heavier than iron.
Origin of the heavy elements in binary neutron-star mergers from a gravitational-wave event.

PubMed

Kasen, Daniel; Metzger, Brian; Barnes, Jennifer; Quataert, Eliot; Ramirez-Ruiz, Enrico

2017-11-02

The cosmic origin of elements heavier than iron has long been uncertain. Theoretical modelling shows that the matter that is expelled in the violent merger of two neutron stars can assemble into heavy elements such as gold and platinum in a process known as rapid neutron capture (r-process) nucleosynthesis. The radioactive decay of isotopes of the heavy elements is predicted to power a distinctive thermal glow (a 'kilonova'). The discovery of an electromagnetic counterpart to the gravitational-wave source GW170817 represents the first opportunity to detect and scrutinize a sample of freshly synthesized r-process elements. Here we report models that predict the electromagnetic emission of kilonovae in detail and enable the mass, velocity and composition of ejecta to be derived from observations. We compare the models to the optical and infrared radiation associated with the GW170817 event to argue that the observed source is a kilonova. We infer the presence of two distinct components of ejecta, one composed primarily of light (atomic mass number less than 140) and one of heavy (atomic mass number greater than 140) r-process elements. The ejected mass and a merger rate inferred from GW170817 imply that such mergers are a dominant mode of r-process production in the Universe.
Electronic structure of clathrates Bax@AlySi46-y ; thermoelectric devices

NASA Astrophysics Data System (ADS)

Eguchi, Haruki; Nagano, Takatoshi; Takenaka, Hiroyuki; Tsumuraya, Kazuo

2002-03-01

Clathrates have received much attention as a candidate of high performance thermoelectric devices. This is because they have a) low thermal conductivity due to rattle effect of the alkali or heavy alkali-earth metals such as Ba atoms in the cages of clusters of the clathrates, and b) adjustablity of the Fermi levels through replacement of frame Si atoms with acceptor Al atoms and addition of the cage atoms as donors. We present the dispersion curves with LDA and GGA approximations for the exchange correlation of electrons using the planewave based pseudopotential methods and predict the electronic properties of the clathrates.
Evaluating the component contribution to nonlinear optical performances using stable [Ni4O4] cuboidal clusters as models.

PubMed

Hao, Zhi-Min; Chao, Meng-Yao; Liu, Yan; Song, Ying-Lin; Yang, Jun-Yi; Ding, Lifeng; Zhang, Wen-Hua; Lang, Jian-Ping

2018-06-19

Five stable clusters sharing the cuboidal [Ni4O4] skeleton are subjected to third-order nonlinear optical (NLO) property measurements. Preliminary results suggest that the NLO property is largely defined by the cluster core skeleton and the directly coordinated atoms, with limited contribution from the heavy atoms peripherally attached to the aromatic ligands.
Atomic-scale visualization of surface-assisted orbital order

PubMed Central

Kim, Howon; Yoshida, Yasuo; Lee, Chi-Cheng; Chang, Tay-Rong; Jeng, Horng-Tay; Lin, Hsin; Haga, Yoshinori; Fisk, Zachary; Hasegawa, Yukio

2017-01-01

Orbital-related physics attracts growing interest in condensed matter research, but direct real-space access of the orbital degree of freedom is challenging. We report a first, real-space, imaging of a surface-assisted orbital ordered structure on a cobalt-terminated surface of the well-studied heavy fermion compound CeCoIn5. Within small tip-sample distances, the cobalt atoms on a cleaved (001) surface take on dumbbell shapes alternatingly aligned in the [100] and [010] directions in scanning tunneling microscopy topographies. First-principles calculations reveal that this structure is a consequence of the staggered dxz-dyz orbital order triggered by enhanced on-site Coulomb interaction at the surface. This so far overlooked surface-assisted orbital ordering may prevail in transition metal oxides, heavy fermion superconductors, and other materials. PMID:28948229
Heaviest Nuclei: New Element with Atomic Number 117

ScienceCinema

Oganessian, Yuri

2018-01-24

One of the fundamental outcomes of the nuclear shell model is the prediction of the 'stability islands' in the domain of the hypothetical super heavy elements. The talk is devoted to the experimental verification of these predictions - the synthesis and study of both the decay and chemical properties of the super heavy elements. The discovery of a new chemical element with atomic number Z=117 is reported. The isotopes 293117 and 294117 were produced in fusion reactions between 48Ca and 249Bk. Decay chains involving 11 new nuclei were identified by means of the Dubna gas-filled recoil separator. The measured decay properties show a strong rise of stability for heavier isotopes with Z =111, validating the concept of the long sought island of enhanced stability for heaviest nuclei.
Relativistic Spin-Orbit Heavy Atom on the Light Atom NMR Chemical Shifts: General Trends Across the Periodic Table Explained.

PubMed

Vícha, Jan; Komorovsky, Stanislav; Repisky, Michal; Marek, Radek; Straka, Michal

2018-06-12

The importance of relativistic effects on the NMR parameters in heavy-atom (HA) compounds, particularly the SO-HALA (Spin-Orbit Heavy Atom on the Light Atom) effect on NMR chemical shifts, has been known for about 40 years. Yet, a general correlation between the electronic structure and SO-HALA effect has been missing. By analyzing 1 H NMR chemical shifts of the sixth-period hydrides (Cs-At), we discovered general electronic-structure principles and mechanisms that dictate the size and sign of the SO-HALA NMR chemical shifts. In brief, partially occupied HA valence shells induce relativistic shielding at the light atom (LA) nuclei, while empty HA valence shells induce relativistic deshielding. In particular, the LA nucleus is relativistically shielded in 5d 2 -5d 8 and 6p 4 HA hydrides and deshielded in 4f 0 , 5d 0 , 6s 0 , and 6p 0 HA hydrides. This general and intuitive concept explains periodic trends in the 1 H NMR chemical shifts along the sixth-period hydrides (Cs-At) studied in this work. We present substantial evidence that the introduced principles have a general validity across the periodic table and can be extended to nonhydride LAs. The decades-old question of why compounds with occupied frontier π molecular orbitals (MOs) cause SO-HALA shielding at the LA nuclei, while the frontier σ MOs cause deshielding is answered. We further derive connection between the SO-HALA NMR chemical shifts and Spin-Orbit-induced Electron Deformation Density (SO-EDD), a property that can be obtained easily from differential electron densities and can be represented graphically. SO-EDD provides an intuitive understanding of the SO-HALA effect in terms of the depletion/concentration of the electron density at LA nuclei caused by spin-orbit coupling due to HA in the presence of a magnetic field. Using an analogy between the SO-EDD concept and arguments from classic NMR theory, the complex question of the SO-HALA NMR chemical shifts becomes easily understandable for a wide chemical audience.
Getting the chemistry right: protonation, tautomers and the importance of H atoms in biological chemistry.

PubMed

Bax, Ben; Chung, Chun Wa; Edge, Colin

2017-02-01

There are more H atoms than any other type of atom in an X-ray crystal structure of a protein-ligand complex, but as H atoms only have one electron they diffract X-rays weakly and are `hard to see'. The positions of many H atoms can be inferred by our chemical knowledge, and such H atoms can be added with confidence in `riding positions'. For some chemical groups, however, there is more ambiguity over the possible hydrogen placements, for example hydroxyls and groups that can exist in multiple protonation states or tautomeric forms. This ambiguity is far from rare, since about 25% of drugs have more than one tautomeric form. This paper focuses on the most common, `prototropic', tautomers, which are isomers that readily interconvert by the exchange of an H atom accompanied by the switch of a single and an adjacent double bond. Hydrogen-exchange rates and different protonation states of compounds (e.g. buffers) are also briefly discussed. The difference in heavy (non-H) atom positions between two tautomers can be small, and careful refinement of all possible tautomers may single out the likely bound ligand tautomer. Experimental methods to determine H-atom positions, such as neutron crystallography, are often technically challenging. Therefore, chemical knowledge and computational approaches are frequently used in conjugation with experimental data to deduce the bound tautomer state. Proton movement is a key feature of many enzymatic reactions, so understanding the orchestration of hydrogen/proton motion is of critical importance to biological chemistry. For example, structural studies have suggested that, just as a chemist may use heat, some enzymes use directional movement to protonate specific O atoms on phosphates to catalyse phosphotransferase reactions. To inhibit `wriggly' enzymes that use movement to effect catalysis, it may be advantageous to have inhibitors that can maintain favourable contacts by adopting different tautomers as the enzyme `wriggles'.
Ion implantation for deterministic single atom devices

NASA Astrophysics Data System (ADS)

Pacheco, J. L.; Singh, M.; Perry, D. L.; Wendt, J. R.; Ten Eyck, G.; Manginell, R. P.; Pluym, T.; Luhman, D. R.; Lilly, M. P.; Carroll, M. S.; Bielejec, E.

2017-12-01

We demonstrate a capability of deterministic doping at the single atom level using a combination of direct write focused ion beam and solid-state ion detectors. The focused ion beam system can position a single ion to within 35 nm of a targeted location and the detection system is sensitive to single low energy heavy ions. This platform can be used to deterministically fabricate single atom devices in materials where the nanostructure and ion detectors can be integrated, including donor-based qubits in Si and color centers in diamond.
Ion implantation for deterministic single atom devices

DOE PAGES

Pacheco, J. L.; Singh, M.; Perry, D. L.; ...

2017-12-04

Here, we demonstrate a capability of deterministic doping at the single atom level using a combination of direct write focused ion beam and solid-state ion detectors. The focused ion beam system can position a single ion to within 35 nm of a targeted location and the detection system is sensitive to single low energy heavy ions. This platform can be used to deterministically fabricate single atom devices in materials where the nanostructure and ion detectors can be integrated, including donor-based qubits in Si and color centers in diamond.
Enhanced nitrogen diffusion induced by atomic attrition

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

Ochoa, E.A.; Figueroa, C.A.; Czerwiec, T.

2006-06-19

The nitrogen diffusion in steel is enhanced by previous atomic attrition with low energy xenon ions. The noble gas bombardment generates nanoscale texture surfaces and stress in the material. The atomic attrition increases nitrogen diffusion at lower temperatures than the ones normally used in standard processes. The stress causes binding energy shifts of the Xe 3d{sub 5/2} electron core level. The heavy ion bombardment control of the texture and stress of the material surfaces may be applied to several plasma processes where diffusing species are involved.
Structure Optimization of 21,23-Core-Modified Porphyrins Absorbing Long-Wavelength Light as Potential Photosensitizers Against Breast Cancer Cells

DTIC Science & Technology

2007-04-01

the core nitrogen atom(s) of natural porphyrins with heavy atoms such as S, Se, and Te provides a red -shift in their absorption spectra [4- 7]. The...shown in red , b in green and c in blue Copyright © 2007 Society of Porphyrins & Phthalocyanines J. Porphyrins Phthalocyanines 2007; 11: 1-8 Y. YOU ET AL...shown in red , b in green and c in blue Copyright © 2007 Society of Porphyrins & Phthalocyanines J. Porphyrins Phthalocyanines 2007; 11: 1-8
Analyzing silver concentration in soil using laser-induced breakdown spectroscopy

NASA Astrophysics Data System (ADS)

Prasetyo, S.; Isnaeni; Zaitun; Mitchell, K.; Suliyanti, M. M.; Herbani, Y.

2018-03-01

Determination of concentration of heavy metal ions in soil, such as silver, is very important to study soil pollution levels. Several techniques have been developed to determine silver ion concentration in soil. In this paper, we utilized laser-induced breakdown spectroscopy (LIBS) to study silver concentration in soil. We used four different data analysis methods to calculate silver concentration. In this case, we prepared soil samples with different silver ion concentrations from 400 ppm to 1000 ppm. Our analysis was focused on the 843.15 nm silver atomic absorption line. We found that plasma intensity increased as silver concentration increased. Our findings were based on our analysis using four different analysis methods. We believe that these analysis methods are able to calculate silver concentration in soil using LIBS.
Solid-phase extraction of some heavy metal ions on a double-walled carbon nanotube disk and determination by flame atomic absorption spectrometry.

PubMed

Karatepe, Aslihan; Soylak, Mustafa; Elçi, Latif

2011-01-01

A new preconcentration method was developed for the determination of trace amounts of Cu(II), Fe(III), Pb(II), Ni(II), and Cd(II) on a double-walled carbon nanotube disk. 4-(2-Thiazolylazo) resorcinol was used as a complexing reagent. The effects of parameters, including pH of the solutions, amounts of complexing reagent, eluent type, sample volume, flow rates of solutions, and matrix ions were examined for quantitative recoveries of the studied analyte ions. The retained metal ions were eluted by 2 M HNO3. The LOD values for the analytes were in the range of 0.7-4.4 microg/mL. Natural water samples and standard reference materials were analyzed by the presented method.
Adsorption of lead over graphite oxide.

PubMed

Olanipekun, Opeyemi; Oyefusi, Adebola; Neelgund, Gururaj M; Oki, Aderemi

2014-01-24

The adsorption efficiency and kinetics of removal of lead in presence of graphite oxide (GO) was determined using the Atomic Absorption Spectrophotometer (AAS). The GO was prepared by the chemical oxidation of graphite and characterized using FTIR, SEM, TGA and XRD. The adsorption efficiency of GO for the solution containing 50, 100 and 150 ppm of Pb(2+) was found to be 98%, 91% and 71% respectively. The adsorption ability of GO was found to be higher than graphite. Therefore, the oxidation of activated carbon in removal of heavy metals may be a viable option to reduce pollution in portable water. Published by Elsevier B.V.
Quantum theory of atoms in molecules: results for the SR-ZORA Hamiltonian.

PubMed

Anderson, James S M; Ayers, Paul W

2011-11-17

The quantum theory of atoms in molecules (QTAIM) is generalized to include relativistic effects using the popular scalar-relativistic zeroth-order regular approximation (SR-ZORA). It is usually assumed that the definition of the atom as a volume bounded by a zero-flux surface of the electron density is closely linked to the form of the kinetic energy, so it is somewhat surprising that the atoms corresponding to the relativistic kinetic-energy operator in the SR-ZORA Hamiltonian are also bounded by zero-flux surfaces. The SR-ZORA Hamiltonian should be sufficient for qualitative descriptions of molecular electronic structure across the periodic table, which suggests that QTAIM-based analysis can be useful for molecules and solids containing heavy atoms.

The influence of the occupational exposure to heavy metals and tobacco smoke on the selected oxidative stress markers in smelters.

PubMed

Sciskalska, Milena; Zalewska, Marta; Grzelak, Agnieszka; Milnerowicz, Halina

2014-06-01

The aim of the study was to verify if there is any association between exposure to Cu, Zn, Cd, Pb, As and the formation of malondialdehyde (MDA), 8-hydroxydeoxyguanosine (8-OHdG), advanced oxidation protein products (AOPP), and whether in this process cigarette smoking plays a role. The investigations were performed in the 352 smelters occupationally exposed to heavy metals and 73 persons of control group. Metals concentration was determined by atomic absorption spectrometry. MDA and AOPP concentrations were determined by spectrophotometric methods. The concentration of 8-OHdG was determined by ELISA method. It was demonstrated an increased Cu concentration in smoking smelters compared to non-smoking control group. It was noted no differences in Zn and Mg concentrations between the examined groups. Pb concentration was more than sixfold higher in the group of smoking smelters and about fivefold higher in the group of non-smoking smelters compared to the control groups (smokers and non-smokers). It was shown that Cd concentration in the blood was nearly fivefold higher in the smoking control group compared to the non-smoking control group and more than threefold higher in the group of smoking smelters compared to non-smoking. It was shown an increased As concentration (more than fourfold) and decreased Ca concentration in both groups of smelters compared to control groups. In groups of smelters (smokers and non-smokers), twofold higher MDA and AOPP concentrations, and AOPP/albumin index compared to control groups (smokers and non-smokers) were shown. Tobacco smoke is the major source of Cd in the blood of smelters. Occupational exposure causes accumulation of Pb in the blood. Occupational exposure to heavy metals causes raise of MDA concentration and causes greater increase in AOPP concentration than tobacco smoke.
Heavy metals accumulation in wood tissues of the forest-forming species growed in the Steppe technogenic landscapes in Ukraine

NASA Astrophysics Data System (ADS)

Lovinska, Viktoriia; Wiche, Oliver

2016-04-01

Territory of Steppe in Ukraine is affected by significant anthropogenic impact caused with mining, metallurgical, chemicalplants and heat power stations. The priority pollutants of the region emissions of these enterprises are presented such heavy metals as Cd, Pb, Cu, Zn, Ni, Mn. The regional forest ecosystems can be considered as potential concentrators of pollutants borned with different technogenic impact. It is necessary to study an ability of forests wood to accumulate heavy metals because accumulated toxins are eliminated from biogeochemical cycle in forest ecosystem for a long time. This study goal is to determine the accumulation properties of forest-forming species - Pinus sylvestris (Scots pine) and Robinia pseudoacacia (black locust) difference age group in relation to heavy metals. It was considerable also to assess the heavy metal distribution in the wood tissue of referred species.Heavy metals content were determined with atomic absorption spectrophotometer using. Scots pine and black locust are the main forest-forming species of natural and artificial forests within Northern Steppe.They can be seen as transformers of the heavy metals cycle and selective concentrators of toxic elements, under the conditions of their excessive concentrations in the environment.It was established that wood tissue of Scots pine and black locust accumulated cadmium in high concentrations according to the age in both species. Indexes of zinc accumulation in the wood of Scots pine exceeded the maximal value in the wood tissue of black locust. The results of our research demonstrated antagonistic interaction of cadmium and zinc. The highest copper concentrations was found for the trees at the age of 45 years. Lead has been identified in wood sample of all ages. Accumulation maximum was fixed in the oldest samples. The trend of concentration increasing of metal didn't find for both species. As for nickel there was established the opposite tendention for both studied species. Nickel maximum accumulation in black locust was fixed for the youngest copies. The same tendency was observed for Scots pine in copies of 45 years old. We did not see relation with age for mangan content in both studied species. The absolute value of the amount of mangan for Scots pine is much higher comparatevelly to black locust.
New Radiation Zones on Jupiter

NASA Image and Video Library

2017-12-11

This graphic shows a new radiation zone surrounding Jupiter, located just above the atmosphere near the equator, that has been discovered by NASA's Juno mission. The new radiation zone is depicted here as a glowing blue area around the planet's middle. This radiation zone includes energetic hydrogen, oxygen and sulfur ions moving at close to the speed of light (referred to as "relativistic" speeds). It resides inside Jupiter's previously known radiation belts. The zone was identified by the mission's Jupiter Energetic Particle Detector Instrument (JEDI), enabled by Juno's unique close approach to the planet during the spacecraft's science flybys (2,100 miles or 3,400 kilometers from the cloud tops). Juno scientists believe the particles creating this region of intense radiation are derived from energetic neutral atoms -- that is, fast-moving atoms without an electric charge -- coming from the tenuous gas around Jupiter's moons Io and Europa. The neutral atoms then become ions -- atoms with an electric charge -- as their electrons are stripped away by interaction with the planet's upper atmosphere. (This discovery is discussed further in an issue of the journal Geophysical Research Letters [Kollmann et al. (2017), Geophys. Res. Lett., 44, 5259-5268].) Juno also has detected signatures of a population of high-energy, heavy ions in the inner edges of Jupiter's relativistic electron radiation belt. This radiation belt was previously understood to contain mostly electrons moving at near light speed. The signatures of the heavy ions are observed at high latitude locations within the electron belt -- a region not previously explored by spacecraft. The origin and exact species of these heavy ions is not yet understood. Juno's Stellar Reference Unit (SRU-1) star camera detects the signatures of this population as extremely high noise in images collected as part of the mission's radiation monitoring investigation. The locations where the heavy ions were detected are indicated on the graphic by two bright, glowing spots along Juno's flight path past the planet, which is shown as a white line. The invisible lines of Jupiter's magnetic field are also portrayed here for context as faint, bluish lines. https://photojournal.jpl.nasa.gov/catalog/PIA22179
Light atom quantum oscillations in UC and US

DOE PAGES

Yiu, Yuen; Aczel, Adam A.; Granroth, Garrett E.; ...

2016-01-19

High energy vibrational scattering in the binary systems UC and US is measured using time-of-flight inelastic neutron scattering. A clear set of well-defined peaks equally separated in energy is observed in UC, corresponding to harmonic oscillations of the light C atoms in a cage of heavy U atoms. The scattering is much weaker in US and only a few oscillator peaks are visible. We show how the difference between the materials can be understood by considering the neutron scattering lengths and masses of the lighter atoms. Monte Carlo ray tracing is used to simulate the scattering, with near quantitative agreementmore » with the data in UC, and some differences with US. The possibility of observing anharmonicity and anisotropy in the potentials of the light atoms is investigated in UC. Lastly, the observed data is well accounted for by considering each light atom as a single atom isotropic quantum harmonic oscillator.« less
On the way to unveiling the atomic structure of superheavy elements

NASA Astrophysics Data System (ADS)

Laatiaoui, Mustapha

2016-12-01

Optical spectroscopy of the transfermium elements (atomic number Z > 100) is nowadays one of the most fascinating and simultaneously challenging tasks in atomic physics. On the one hand, key atomic and even nuclear ground-state properties may be obtained by studying the spectral lines of these heaviest elements. On the other hand, these elements have to be produced "online" by heavy-ion induced fusion-evaporation reactions yielding rates on the order of a few atoms per second at most, which renders their optical spectroscopy extremely difficult. Only recently, a first foray of laser spectroscopy into this heaviest element region was reported. Several atomic transitions in the element nobelium (Z = 102) were observed and characterized, using an ultra-sensitive and highly efficient resonance ionization technique. The findings confirm the predictions and additionally provide a benchmark for theoretical modelling. The work represents an important stepping stone towards experimental studies of the atomic structure of superheavy elements.
The effect of diffuse basis functions on valence bond structural weights

NASA Astrophysics Data System (ADS)

Galbraith, John Morrison; James, Andrew M.; Nemes, Coleen T.

2014-03-01

Structural weights and bond dissociation energies have been determined for H-F, H-X, and F-X molecules (-X = -OH, -NH2, and -CH3) at the valence bond self-consistent field (VBSCF) and breathing orbital valence bond (BOVB) levels of theory with the aug-cc-pVDZ and 6-31++G(d,p) basis sets. At the BOVB level, the aug-cc-pVDZ basis set yields a counterintuitive ordering of ionic structural weights when the initial heavy atom s-type basis functions are included. For H-F, H-OH, and F-X, the ordering follows chemical intuition when these basis functions are not included. These counterintuitive weights are shown to be a result of the diffuse polarisation function on one VB fragment being spatially located, in part, on the other VB fragment. Except in the case of F-CH3, this problem is corrected with the 6-31++G(d,p) basis set. The initial heavy atom s-type functions are shown to make an important contribution to the VB orbitals and bond dissociation energies and, therefore, should not be excluded. It is recommended to not use diffuse basis sets in valence bond calculations unless absolutely necessary. If diffuse basis sets are needed, the 6-31++G(d,p) basis set should be used with caution and the structural weights checked against VBSCF values which have been shown to follow the expected ordering in all cases.
Estimating inelastic heavy-particle-hydrogen collision data. I. Simplified model and application to potassium-hydrogen collisions

NASA Astrophysics Data System (ADS)

Belyaev, Andrey K.; Yakovleva, Svetlana A.

2017-10-01

Aims: We derive a simplified model for estimating atomic data on inelastic processes in low-energy collisions of heavy-particles with hydrogen, in particular for the inelastic processes with high and moderate rate coefficients. It is known that these processes are important for non-LTE modeling of cool stellar atmospheres. Methods: Rate coefficients are evaluated using a derived method, which is a simplified version of a recently proposed approach based on the asymptotic method for electronic structure calculations and the Landau-Zener model for nonadiabatic transition probability determination. Results: The rate coefficients are found to be expressed via statistical probabilities and reduced rate coefficients. It turns out that the reduced rate coefficients for mutual neutralization and ion-pair formation processes depend on single electronic bound energies of an atom, while the reduced rate coefficients for excitation and de-excitation processes depend on two electronic bound energies. The reduced rate coefficients are calculated and tabulated as functions of electronic bound energies. The derived model is applied to potassium-hydrogen collisions. For the first time, rate coefficients are evaluated for inelastic processes in K+H and K++H- collisions for all transitions from ground states up to and including ionic states. Tables with calculated data are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/606/A147
Relaxation of heavy species and gas temperature in the afterglow of a N2 microwave discharge

NASA Astrophysics Data System (ADS)

Pintassilgo, Carlos D.; Guerra, Vasco

2017-10-01

In this paper we present a self-consistent kinetic model to study the temporal variation of the gas temperature in the afterglow of a 440 Pa microwave nitrogen discharge operating at 433 MHz in a 3.8 cm diameter tube. The initial conditions in the afterglow are determined by a kinetic model that solves the electron Boltzmann equation coupled to the gas thermal balance equation and a system of rate-balance equations for N2(X 1∑g+, v) molecules, electronically excited states of N2, ground and excited states of atomic nitrogen and the main positive ions. Once the initial concentrations of the heavy species and gas temperature are known, their relaxation in the afterglow is obtained from the solutions to the corresponding time-dependent equations. Modelling predictions are found to be in good agreement with previously measured values for the concentrations of N(4S) atoms and N2(A 3∑u+) molecules, and the radially averaged gas temperature Tg along the afterglow of a microwave discharge in N2 under the same working conditions. It is shown that gas heating in the afterglow comes essentially from the energy transfer involving non-resonant vibration-vibration (V-V) collisions between vibrationally excited nitrogen molecules, as well as from energy exchanges in vibration-translation (V-T) on N2-N collisions. Contribution to the topical issue "Plasma Sources and Plasma Processes (PSPP)", edited by Luis Lemos Alves, Thierry Belmonte and Tiberiu Minea
CCR2 and CCR5 receptor-binding properties of herpesvirus-8 vMIP-II based on sequence analysis and its solution structure.

PubMed

Shao, W; Fernandez, E; Sachpatzidis, A; Wilken, J; Thompson, D A; Schweitzer, B I; Lolis, E

2001-05-01

Human herpesvirus-8 (HHV-8) is the infectious agent responsible for Kaposi's sarcoma and encodes a protein, macrophage inflammatory protein-II (vMIP-II), which shows sequence similarity to the human CC chemokines. vMIP-II has broad receptor specificity that crosses chemokine receptor subfamilies, and inhibits HIV-1 viral entry mediated by numerous chemokine receptors. In this study, the solution structure of chemically synthesized vMIP-II was determined by nuclear magnetic resonance. The protein is a monomer and possesses the chemokine fold consisting of a flexible N-terminus, three antiparallel beta strands, and a C-terminal alpha helix. Except for the N-terminal residues (residues 1-13) and the last two C-terminal residues (residues 73-74), the structure of vMIP-II is well-defined, exhibiting average rmsd of 0.35 and 0.90 A for the backbone heavy atoms and all heavy atoms of residues 14-72, respectively. Taking into account the sequence differences between the various CC chemokines and comparing their three-dimensional structures allows us to implicate residues that influence the quaternary structure and receptor binding and activation of these proteins in solution. The analysis of the sequence and three-dimensional structure of vMIP-II indicates the presence of epitopes involved in binding two receptors CCR2 and CCR5. We propose that vMIP-II was initially specific for CCR5 and acquired receptor-binding properties to CCR2 and other chemokine receptors.
Effects of Ion Atomic Number on Single-Event Gate Rupture (SEGR) Susceptibility of Power MOSFETs

NASA Technical Reports Server (NTRS)

Lauenstein, Jean-Marie; Goldsman, Neil; Liu, Sandra; Titus, Jeffrey L.; Ladbury, Raymond L.; Kim, Hak S.; Phan, Anthony M.; LaBel, Kenneth A.; Zafrani, Max; Sherman, Phillip

2012-01-01

The relative importance of heavy-ion interaction with the oxide, charge ionized in the epilayer, and charge ionized in the drain substrate, on the bias for SEGR failure in vertical power MOSFETs is experimentally investigated. The results indicate that both the charge ionized in the epilayer and the ion atomic number are important parameters of SEGR failure. Implications on SEGR hardness assurance are discussed.
Industrial Mobilization: The Relevant History. Revised

DTIC Science & Technology

1983-01-01

purpose was much too narrow and, in fact, wrong in its basic premise. In- stead, I adopted a more useful goal, i.e., to describe and analyze the...production of defense Items or research and development for DOD and the Atomic Energy Commission. The hearings had resultod from competition between two...I II| rll ll ll I.I -. _- History of Korean War Ere such as atomic energy plants and facilities housing heavy presses
Remediation of lead and cadmium-contaminated soils.

PubMed

Salama, Ahmed K; Osman, Khaled A; Gouda, Neama Abdel-Razeek

2016-01-01

The research was designated to study the ability of plants to bio-accumulate, translocate and remove the heavy metals, lead and cadmium from contaminated soil. The herbal plant ryegrass, Lolium multiflorum was investigated as a bio-accumulator plant for these metals. The translocation of these heavy metals in the herbal plant was compared considering root to shoot transport and redistribution of metals in the root and shoot system. The trace metal contents from root and shoot parts were determined using atomic absorption spectrometer. The results showed that the percent of lead and cadmium transferred to ryegrass plant were averaged as 51.39, and 74.57%, respectively, while those remained in the soil were averaged as 48.61 and 25.43% following 60 days of treatment. The soil-plant transfer index in root and shoot system of ryegrass was found to be 0.32 and 0.20 for lead, and 0.50 and 0.25 for cadmium. These findings indicated that the herbal plant ryegrass, Lolium multiflorum is a good accumulator for cadmium than lead. The soil-plant transfer factor (the conc. of heavy metal in plant to the conc. in soil) indicated that the mechanism of soil remedy using the investigated plant is phytoextraction where the amounts of heavy metals transferred by plant roots into the above ground portions were higher than that remained in the soil. The method offers green technology solution for the contamination problem since it is effective technology with minimal impact on the environment and can be easily used for soil remedy.
Total mercury, methyl mercury, and heavy metal concentrations in Hyeongsan River and its tributaries in Pohang city, South Korea.

PubMed

Bailon, Mark Xavier; David, Anneschel Sheehan; Park, Yeongeon; Kim, Eunhee; Hong, Yongseok

2018-04-11

Heavy metal contamination in aquatic systems is a big problem in many areas around the world. In 2016, high mercury concentrations were reported in bivalves (Corbicula leana) and sediments near the confluence of the Hyeongsan River and Chilseong Creek located in Pohang, a steel industrial city in the south-east coast of the Korean peninsula. Given that both the Chilseong and Gumu creeks run through the Pohang industrial complex and ultimately flow to the Hyeongsan River, it is imperative to determine if the industrial effluents have any impact on the mercury contamination in these two streams and the Hyeongsan River. In this work, we investigated the concentration levels of different heavy metals using cold vapor atomic fluorescence spectroscopy and inductively coupled plasma-mass spectroscopy. The metal concentration in the water samples from the Hyeongsan River, Gumu Creek, and Chilseong Creek did not exceed the limits for drinking water quality set by the US EPA and World Health Organization. However, the sediment samples were found to be heavily contaminated by Hg with levels exceeding the toxic effect threshold. Gumu Creek was found to be heavily contaminated. The concentrations of the different heavy metals increased downstream, and the samples collected from the sites in the Hyeongsan River near the Gumu Creek, an open channel for wastewater discharge of companies in the Pohang Industrial Complex, showed higher contamination levels, indicating that the effluents from the industrial complex are a possible source of contamination in the river.
Nonextensive Thomas-Fermi model

NASA Astrophysics Data System (ADS)

Shivamoggi, Bhimsen; Martinenko, Evgeny

2007-11-01

Nonextensive Thomas-Fermi model was father investigated in the following directions: Heavy atom in strong magnetic field. following Shivamoggi work on the extension of Kadomtsev equation we applied nonextensive formalism to father generalize TF model for the very strong magnetic fields (of order 10e12 G). The generalized TF equation and the binding energy of atom were calculated which contain a new nonextensive term dominating the classical one. The binding energy of a heavy atom was also evaluated. Thomas-Fermi equations in N dimensions which is technically the same as in Shivamoggi (1998) ,but behavior is different and in interesting 2 D case nonextesivity prevents from becoming linear ODE as in classical case. Effect of nonextensivity on dielectrical screening reveals itself in the reduction of the envelope radius. It was shown that nonextesivity in each case is responsible for new term dominating classical thermal correction term by order of magnitude, which is vanishing in a limit q->1. Therefore it appears that nonextensive term is ubiquitous for a wide range of systems and father work is needed to understand the origin of it.
Measuring mercury and other elemental components in tree rings

USGS Publications Warehouse

Gillan, C.; Hollerman, W.A.; Doyle, T.W.; Lewis, T.E.

2004-01-01

There has been considerable interest in measuring heavy metal pollution, such as mercury, using tree ring analysis. Since 1970, this method has provided a historical snapshot of pollutant concentrations near hazardous waste sites. Traditional methods of analysis have long been used with heavy metal pollutants such as mercury. These methods, such as atomic fluorescence and laser ablation, are sometimes time consuming and expensive to implement. In recent years, ion beam techniques, such as Particle Induced X-Ray Emission (PIXE), have been used to measure large numbers of elements. Most of the existing research in this area has been completed for low to medium atomic number pollutants, such as titanium, cobalt, nickel, and copper. Due to the reduction of sensitivity, it is often difficult or impossible to use traditional low energy (few MeV) PIXE analysis for pollutants with large atomic numbers. For example, the PIXE detection limit for mercury was recently measured to be about 1 ppm for a spiked Southern Magnolia wood sample [ref. 1]. This presentation will compare PIXE and standard chemical concentration results for a variety of wood samples.
Measuring mercury and other elemental components in tree rings

USGS Publications Warehouse

Gillan, C.; Hollerman, W.A.; Doyle, T.W.; Lewis, T.E.

2004-01-01

There has been considerable interest in measuring heavy metal pollution, such as mercury, using tree ring analysis. Since 1970, this method has provided a historical snapshot of pollutant concentrations near hazardous waste sites. Traditional methods of analysis have long been used with heavy metal pollutants such as mercury. These methods, such as atomic fluorescence and laser ablation, are sometimes time consuming and expensive to implement. In recent years, ion beam techniques, such as Particle Induced X-Ray Emission (PIXE), have been used to measure large numbers of elements. Most of the existing research in this area has been completed for low to medium atomic number pollutants, such as titanium, cobalt, nickel, and copper. Due to the reduction of sensitivity, it is often difficult or impossible to use traditional low energy (few MeV) PIXE analysis for pollutants with large atomic numbers. For example, the PIXE detection limit for mercury was recently measured to be about 1 ppm for a spiked Southern Magnolia wood sample [ref. 1]. This presentation will compare PIXE and standard chemical concentration results for a variety of wood samples. Copyright 2004 by ISA.
[Climatic analysis of heavy metal concentration associated with urban road-deposited sediment].

PubMed

Zafra-Mejía, Carlos; Santamaría-Galindo, Diana M; Torres-Galindo, Cristian D

2015-05-01

Objective To climatically assess (daily) the concentration of heavy metals (Pb and Cu) in sediment deposited on road surfaces of the localities of Kennedy and Puente Aranda (Bogota, D.C., Colombia). Additionally, the detected concentrations are to be evaluated with respect to the legislation chosen as reference point for the protection of human health in urban areas. Methods The concentration was determined by flame atomic absorption spectrometry. The samples were previously digested in a mixture of hydrochloric and nitric acid (3:1; aqua regia). Results The results show, with respect to road sediment closest to the size that could be potentially inhaled from the point of view of public health (≤ 10 µm), that the metal concentrations on average tend to increase in dry weather (29 %). In this regard, the concentrations during these time periods are on average 1.69 times higher than the lowest limit value set by the reference legislation. However, it is suggested that the metal concentrations are mostly due to the use of the land rather than weather conditions. Conclusions The findings are a reference point in Colombia for the discussion and publication of environmental regulations associated with the protection of human health from heavy metals and for visualizing future lines of research about the effect of climate change on metal concentrations in urban environments.
Comparative Assessment of Heavy Metals in Drinking Water Sources in Two Small-Scale Mining Communities in Northern Ghana.

PubMed

Cobbina, Samuel J; Duwiejuah, Abudu B; Quansah, Reginald; Obiri, Samuel; Bakobie, Noel

2015-08-28

The study assessed levels of heavy metals in drinking water sources in two small-scale mining communities (Nangodi and Tinga) in northern Ghana. Seventy-two (72) water samples were collected from boreholes, hand dug wells, dug-out, and a stream in the two mining communities. The levels of mercury (Hg), arsenic (As), lead (Pb), zinc (Zn), and cadmium (Cd) were determined using an atomic absorption spectrophotometer (AAS). Mean levels (mg/l) of heavy metals in water samples from Nangodi and Tinga communities were 0.038 and 0.064 (Hg), 0.031 and 0.002 (As), 0.250 and 0.031 (Pb), 0.034 and 0.002 (Zn), and 0.534 and 0.023 (Cd), respectively, for each community. Generally, levels of Hg, As, Pb, Zn, and Cd in water from Nangodi exceeded the World Health Organisation (WHO) stipulated limits of 0.010 for Hg, As, and Pb, 3.0 for Zn and 0.003 for Cd for drinking water, and levels of Hg, Pb, and Cd recorded in Tinga, exceeded the stipulated WHO limits. Ingestion of water, containing elevated levels of Hg, As, and Cd by residents in these mining communities may pose significant health risks. Continuous monitoring of the quality of drinking water sources in these two communities is recommended.
Comparative Assessment of Heavy Metals in Drinking Water Sources in Two Small-Scale Mining Communities in Northern Ghana

PubMed Central

Cobbina, Samuel J.; Duwiejuah, Abudu B.; Quansah, Reginald; Obiri, Samuel; Bakobie, Noel

2015-01-01

The study assessed levels of heavy metals in drinking water sources in two small-scale mining communities (Nangodi and Tinga) in northern Ghana. Seventy-two (72) water samples were collected from boreholes, hand dug wells, dug-out, and a stream in the two mining communities. The levels of mercury (Hg), arsenic (As), lead (Pb), zinc (Zn), and cadmium (Cd) were determined using an atomic absorption spectrophotometer (AAS). Mean levels (mg/l) of heavy metals in water samples from Nangodi and Tinga communities were 0.038 and 0.064 (Hg), 0.031 and 0.002 (As), 0.250 and 0.031 (Pb), 0.034 and 0.002 (Zn), and 0.534 and 0.023 (Cd), respectively, for each community. Generally, levels of Hg, As, Pb, Zn, and Cd in water from Nangodi exceeded the World Health Organisation (WHO) stipulated limits of 0.010 for Hg, As, and Pb, 3.0 for Zn and 0.003 for Cd for drinking water, and levels of Hg, Pb, and Cd recorded in Tinga, exceeded the stipulated WHO limits. Ingestion of water, containing elevated levels of Hg, As, and Cd by residents in these mining communities may pose significant health risks. Continuous monitoring of the quality of drinking water sources in these two communities is recommended. PMID:26343702
The gas phase structure of α -pinene, a main biogenic volatile organic compound

NASA Astrophysics Data System (ADS)

Neeman, Elias M.; Avilés Moreno, Juan Ramón; Huet, Thérèse R.

2017-12-01

The gas phase structure of the bicyclic atmospheric aerosol precursor α-pinene was investigated employing a combination of quantum chemical calculation and Fourier transform microwave spectroscopy coupled to a supersonic jet expansion. The very weak rotational spectra of the parent species and all singly substituted 13C in natural abundance have been identified, from 2 to 20 GHz, and fitted to Watson's Hamiltonian model. The rotational constants were used together with geometrical parameters from density functional theory and ab initio calculations to determine the rs, r0, and rm(1 ) structures of the skeleton, without any structural assumption in the fit concerning the heavy atoms. The double C=C bond was found to belong to a quasiplanar skeleton structure containing 6 carbon atoms. Comparison with solid phase structure is reported. The significant differences of α-pinene in gas phase and other gas phase bicyclic monoterpene structures (β-pinene, nopinone, myrtenal, and bicyclo[3.1.1]heptane) are discussed.

The P-factor and atomic mass systematics: Application to medium mass nuclei

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

Brenner, D.S.; Haustein, P.E.; Casten, R.F.

1988-01-01

The P formalism was applied to atomic mass systematics for medium and heavy nuclei. The P-factor linearizes the structure-dependent part of the nuclear mass in those regions which are free from subshell effects indicating that the attractive quadrupole p-n force plays an important role in determining the binding of valence nucleons. Where marked non-linearities occur, the P-factor provides a means for recognizing subshell closures and/or other structural features not embodied in the simple assumptions of abrupt shell or subshell changes. These are thought to be regions where the monopole part of the p-n interaction is highly orbit dependent and altersmore » the underlying single-particle structure as a function of A, N or Z. Finally, in those regions where the systematics are smooth and subshells are absent, the P-factor provides a means for predicting masses of some nuclei far-from-stability by interpolation rather than by extrapolation. 5 figs.« less
Simulation of FRET dyes allows quantitative comparison against experimental data

NASA Astrophysics Data System (ADS)

Reinartz, Ines; Sinner, Claude; Nettels, Daniel; Stucki-Buchli, Brigitte; Stockmar, Florian; Panek, Pawel T.; Jacob, Christoph R.; Nienhaus, Gerd Ulrich; Schuler, Benjamin; Schug, Alexander

2018-03-01

Fully understanding biomolecular function requires detailed insight into the systems' structural dynamics. Powerful experimental techniques such as single molecule Förster Resonance Energy Transfer (FRET) provide access to such dynamic information yet have to be carefully interpreted. Molecular simulations can complement these experiments but typically face limits in accessing slow time scales and large or unstructured systems. Here, we introduce a coarse-grained simulation technique that tackles these challenges. While requiring only few parameters, we maintain full protein flexibility and include all heavy atoms of proteins, linkers, and dyes. We are able to sufficiently reduce computational demands to simulate large or heterogeneous structural dynamics and ensembles on slow time scales found in, e.g., protein folding. The simulations allow for calculating FRET efficiencies which quantitatively agree with experimentally determined values. By providing atomically resolved trajectories, this work supports the planning and microscopic interpretation of experiments. Overall, these results highlight how simulations and experiments can complement each other leading to new insights into biomolecular dynamics and function.
Production and decay of K -shell hollow krypton in collisions with 52-197-MeV/u bare xenon ions

NASA Astrophysics Data System (ADS)

Shao, Caojie; Yu, Deyang; Cai, Xiaohong; Chen, Xi; Ma, Kun; Evslin, Jarah; Xue, Yingli; Wang, Wei; Kozhedub, Yury S.; Lu, Rongchun; Song, Zhangyong; Zhang, Mingwu; Liu, Junliang; Yang, Bian; Guo, Yipan; Zhang, Jianming; Ruan, Fangfang; Wu, Yehong; Zhang, Yuezhao; Dong, Chenzhong; Chen, Ximeng; Yang, Zhihu

2017-07-01

X-ray spectra of K -shell hollow krypton atoms produced in single collisions with 52-197-MeV/u X e54 + ions are measured in a heavy-ion storage ring equipped with an internal gas-jet target. Energy shifts of the K α1,2 s , K α1,2 h ,s , and K β1,3 s transitions are obtained. Thus the average number of the spectator L vacancies presented during the x-ray emission is deduced. From the relative intensities of the K α1,2 s and K α1,2 h ,s transitions, the ratio of K -shell hollow krypton to singly K -shell ionized atoms is determined to be 14 %-24 % . In the considered collisions, the K vacancies are mainly created by the direct ionization which cannot be calculated within the perturbation descriptions. The experimental results are compared with a relativistic coupled-channel calculation performed within the independent particle approximation.
Use of Bioassay test for the environmental evaluation of mining residues and their leachates: the singular case of the Portman Bay (SE, Spain)

NASA Astrophysics Data System (ADS)

Martínez-Sánchez, Maria Jose; García-Lorenzo, Maria Luz; Pérez-Sirvent, Carmen; Molina, Jose; Tudela, Maria Luz; Hernández-Córdoba, Manuel

2010-05-01

The aim of the present study was to evaluate the toxicity of sediments and their pore-water extracts from sites contaminated by mining activities using two assays: bacteria and plants. The acute toxicity in pore-waters was determined using the Microtox® bioassay, which uses the naturally luminescent marine bacterium Vibrio fischeri. Phytotoxicity in soil samples was tested by way of the seed germination and root elongation technique in three plant species, Sorghum saccharatum, Sinapis alba and Lepidium sativum. The aim of applying these assays is to establish a method for evaluating the real risks within a risk analysis process, considering both present and future risks, bearing in mind that the uses to which soil is put (urban, recreational or industrial) may change. In the zone studied, mining activities have led to heavy metal contamination with the risk of runoff and wind dispersion of the contaminated material. For this study, 6 sediment samples were collected from Portman Bay (Murcia, SE Spain). The soil extract was prepared by saturation with distilled water and allowing it to stand for four hours. Then, the soil was subjected to a vacuum pressure to extract the soil solution through filter paper. The Zn and Fe content was determined by flame atomic absorption spectrometry (FAAS). The Pb, Cd and Cu content was determined by electrothermal atomization atomic absorption spectrometry (ETAAS). The As content was analysed by atomic fluorescence spectrometry using an automated continuous flow hydride generation (As-AFS) spectrometer. Total Pb concentration varied from 600 to 2500 ppm, with a mean value of 1200 ppm. The average content of Zn was 5300 ppm. The mean concentration of Cd and Cu was 23 and 59 ppm, respectively. Total As concentrations varied from 180 to 470 ppm, with an average value 280 ppm. Finally, the total Fe content ranged from 37% to 47%, with an average value of 40%. Pore-water samples showed neutral pH values and average electrical conductivity was 8.4 ds m-1. Mean heavy metal content in leachates from Portman Bay was 6.8 ppm for Pb, 0.1 ppm for Zn, 17 ppb for Cd, 5.6 ppb for Cu, 3.7 ppb for As and 0.6 ppm for Fe. The bioassays showed different sensitivities to the target metals. The Vibrio fischeri luminescence inhibition assay showed less sensitivity to the toxicants in the sediments than phytotoxicity assay. According to our results it is highly advisable to complement chemical analyses with environmental toxicity testing to characterise the risks presented by contaminated soils. Finally, these methods satisfy the requirements of environmental toxicology in their reliability, sensitivity, reproducibility, rapidity and low cost.
Heavy metal concentration in groundwater from Besant Nagar to Sathankuppam, South Chennai, Tamil Nadu, India

NASA Astrophysics Data System (ADS)

Sridhar, S. G. D.; Sakthivel, A. M.; Sangunathan, U.; Balasubramanian, M.; Jenefer, S.; Mohamed Rafik, M.; Kanagaraj, G.

2017-12-01

The assessment of groundwater quality is an obligatory pre-requisite to developing countries like India with rural-based economy. Heavy metal concentration in groundwater from Besant Nagar to Sathankuppam, South Chennai was analyzed to assess the acquisition process. The study area has rapid urbanization since few decades, which deteriorated the condition of the aquifer of the area. Totally 30 groundwater samples were collected during pre-monsoon (June 2014) and post-monsoon (January 2015) from the same aquifer to assess the heavy metal concentration in groundwater. Groundwater samples were analyzed for heavy metals such as Fe, Pb, Zn, Cu, Ni, Cr, Co and Mn using atomic absorption spectrophotometry (AAS). Correlation matrix revealed that there is no significant correlation between heavy metals and other parameters during pre-monsoon except EC with Cr but Fe and Zn have good positive correlation during post-monsoon.
[Comparison of heavy metal elements between natural and plantation forests in a subtropical Montane forest].

PubMed

Nie, Ming; Wan, Jia-Rong; Chen, Xiao-Feng; Wang, Li; Li, Bo; Chen, Jia-Kuan

2011-11-01

Heavy metals as one of major pollutants is harmful to the health of forest ecosystems. In the present paper, the concentrations of thirteen heavy metals (Fe, Al, Ti, Cr, Cu, Mn, V, Zn, Ni, Co, Pb, Se and Cd) were compared between natural and plantation forests in the Mt. Lushan by ICP-AES and atomic absorption spectroscopy. The results suggest that the soil of natural forest had higher concentrations of Fe, Al, Ti, Cu, Mn, V, Zn, Ni, Co, Pb, Se, and Cd than the plantation forest except for Cr. The soil of natural forest had a higher level of heavy metals than that of the plantation forest as a whole. This might be due to that the natural forest has longer age than the plantation forest, and fixed soil heavy metals take a longer period of time than the plantation forest.
MARINE D-BLUE CLEAN™

EPA Pesticide Factsheets

Technical product bulletin: this dispersant is used in oil spill cleanups on salt water, sprayed onto slick in atomized form using moderately coarse droplets rather than fine mist. Effective with crude and residual heavy oil spills.
NEOS AB3000

EPA Pesticide Factsheets

Technical product bulletin: this hydrocarbon solvent based dispersant used in oil spill cleanups can be sprayed neat on the oil slick in atomized form. Effective with crude and residual heavy oil, and also at controlling volatile emissions.
Applications of beam-foil spectroscopy to atomic collisions in solids

NASA Technical Reports Server (NTRS)

Sellin, I. A.

1976-01-01

Some selected papers presented at the Fourth International Conference on Beam-Foil Spectroscopy, whose results are of particular pertinence to ionic collision phenomena in solids, are reviewed. The topics discussed include solid target effects and means of surmounting them in the measurement of excited projectile ion lifetimes for low-energy heavy element ions; the electron emission accompanying the passage of heavy particles through solid targets; the collision broadening of X rays emitted from 100 keV ions moving in solids; residual K-shell excitation in chlorine ions penetrating carbon; comparison between 40 MeV Si on gaseous SiH4 targets at 300 mtorr and 40 MeV Si on Al; and the emergent surface interaction in beam-foil spectroscopy. A distinct overlap of interests between the sciences of beam-foil spectroscopy and atomic collisions in solids is pointed out.
Elliptic flow from Coulomb interaction and low density elastic scattering

NASA Astrophysics Data System (ADS)

Sun, Yuliang; Li, Qingfeng; Wang, Fuqiang

2018-04-01

In high energy heavy ion collisions and interacting cold atom systems, large elliptic flow anisotropies have been observed. For the large opacity (ρ σ L ˜103 ) of the latter hydrodynamics is a natural consequence, but for the small opacity (ρ σ L ˜1 ) of the former the hydrodynamic description is questionable. To shed light onto the situation, we simulate the expansion of a low density argon ion (or atom) system, initially trapped in an elliptical region, under the Coulomb interaction (or elastic scattering). Significant elliptic anisotropy is found in both cases, and the anisotropy depends on the initial spatial eccentricity and the density of the system. The results may provide insights into the physics of anisotropic flow in high energy heavy ion collisions and its role in the study of quantum chromodynamics.
Computer simulation of sputtering induced by swift heavy ions

NASA Astrophysics Data System (ADS)

Kucharczyk, P.; Füngerlings, A.; Weidtmann, B.; Wucher, A.

2018-07-01

New experimental results regarding the mass and charge state distribution of material sputtered under irradiation with swift heavy ions suggest fundamental differences between the ejection mechanisms under electronic and nuclear sputtering conditions. In order to illustrate the difference, computer simulations based on molecular dynamics were performed to model the surface ejection process of atoms and molecules induced by a swift heavy ion track. In a first approach, the track is homogeneously energized by assigning a fixed energy to each atom with randomly oriented direction of motion within a cylinder of a given radius around the projectile ion trace. The remainder of the target crystal is assumed to be at rest, and the resulting lattice dynamics is followed by molecular dynamics. The resulting sputter yield is calculated as a function of track radius and energy and compared to corresponding experimental data in order to find realistic values for the effective deposited lattice energy density. The sputtered material is analyzed with respect to emission angle and energy as well as depth of origin. The results are compared to corresponding data from keV sputter simulations. As a second step of complexity, the homogeneous and monoenergetic lattice energization is replaced by a starting energy distribution described by a local lattice temperature. As a first attempt, the respective temperature is assumed constant within the track, and the results are compared with those obtained from monoenergetic energization with the same average energy per atom.
Matrix elimination method for the determination of precious metals in ores using electrothermal atomic absorption spectrometry.

PubMed

Salih, Bekir; Celikbiçak, Omür; Döker, Serhat; Doğan, Mehmet

2007-03-28

Poly(N-(hydroxymethyl)methacrylamide)-1-allyl-2-thiourea) hydrogels, poly(NHMMA-ATU), were synthesized by gamma radiation using (60)Co gamma source in the ternary mixture of NHMMA-ATU-H(2)O. These hydrogels were used for the specific gold, silver, platinum and palladium recovery, pre-concentration and matrix elimination from the solutions containing trace amounts of precious metal ions. Elimination of inorganic matrices such as different transition and heavy metal ions, and anions was performed by adjusting the solution pH to 0.5 that was the selective adsorption pH of the precious metal ions. Desorption of the precious metal ions was performed by using 0.8 M thiourea in 3M HCl as the most efficient desorbing agent with recovery values more than 95%. In the desorption medium, thiourea effect on the atomic signal was eliminated by selecting proper pyrolysis and atomization temperatures for all precious metal ions. Precision and the accuracy of the results were improved in the graphite furnace-atomic absorption spectrometer (GFAAS) measurements by applying the developed matrix elimination method performing the adsorption at pH 0.5. Pre-concentration factors of the studied precious metal ions were found to be at least 1000-fold. Detection limits of the precious metal ions were found to be less than 10 ng L(-1) of the all studied precious metal ions by using the proposed pre-concentration method. Determination of trace levels of the precious metals in the sea-water, anode slime, geological samples and photographic fixer solutions were performed using GFAAS clearly after applying the adsorption-desorption cycle onto the poly(NHMMA-UTU) hydrogels.
Possible impact of multi-electron loss events on the average beam charge state in an HIF target chamber and a neutral beam approach

NASA Astrophysics Data System (ADS)

Grisham, L. R.

2001-05-01

Experiments were carried out during the early 1980s to assess the obtainable atomic neutralization of energetic beams of negative ions ranging from lithium to silicon. The experiments found (Grisham et al. Rev. Sci. Instrum. 53 (1982) 281; Princeton Plasma Physics Laboratory Report PPPL-1857, 1981) that, for higher atomic number elements than lithium, it appeared that a substantial fraction of the time more than one electron was being lost in a single collision. This result was inferred from the existence of more than one ionization state in the product beam for even the thinnest line densities at which any electron removal took place. Because of accelerator limitations, these experiments were limited to maximum energies of 7 MeV. However, based upon these results, it is possible that multi-electron loss events may also play a significant role in determining the average ion charge state of the much higher Z and more energetic beams traversing the medium in an heavy ion fusion chamber. This could result in the beam charge state being considerably higher than previously anticipated, and might require designers to consider harder vacuum ballistic focusing approaches, or the development of additional space charge neutralization schemes. This paper discusses the measurements that gave rise for these concerns, as well as a description of further measurements that are proposed to be carried out for atomic numbers and energies per amu which would be closer to those required for heavy ion fusion drivers. With a very low current beam of a massive, but low charge state energetic ion, the charge state distribution emerging from a target gas cell could be measured as a function of line density and medium composition. Varying the line density would allow one to simulate the charge state evolution of the beam as a function of distance into the target chamber. This paper also briefly discusses a possible alternative driver approach using photodetachment-neutralized atomic beams, which could reduce plasma complications far from the target, but which would impose more stringent limitations upon chamber pressure and repetition rate.
A Simple and Fast Method Based on New Magnetic Ion Imprinted Polymer as a Highly Selective Sorbent for Preconcentration and Determination of Cadmium in Environmental Samples

PubMed Central

PANJALI, Zahra; ASGHARINEZHAD, Ali Akbar; EBRAHIMZADEH, Homeira; JALILIAN, Niloofar; YARAHMADI, Rasoul; SHAHTAHERI, Seyed Jamaleddin

2016-01-01

Background: The analysis of heavy metals at trace level is one of the main toxicologists concern, due to their vital rules in human`s life. Cadmium is one of these toxic heavy metals, which released to the environment from various industries. Methods: In order to determine Cd (II) ions in various matrices magnetic ion-imprinted polymer (IIP) method has been developed and applied. This nano-sorbent has been synthesized by coating an IIP compound on Fe3O4 nanoparticles core to achieve highest surface area. This polymer has been used to evaluate Cd (II) levels in food, river, and wastewater in Tehran, Iran. Results: Fe3O4@Cd-IIP was stable up to 300 °C. The various factors such as sample pH (optimized as 7), elution/sorption time (5 min), eluent amount (4 mL HCL), and its concentration (2 mol L−1) were optimized. Analysis instrument in all steps was Flame Atomic Abortion Spectrophotometer (FAAS). In this study, the detection limit was determined down to 0.6 μg L−1. Conclusion: This method was applied successfully for the preconcentration and determination of Cd (II) ions in environmental samples obtained from rivers, various foods and wastewater. In addition, the accuracy of the method was confirmed by analyzing a certified reference material (Seronorm LOT NO2525) and spiked real samples. PMID:27928531
Concentrations of lead, cadmium, mercury and other elements in seeds of Lupinus mutabilis and of other legumes.

PubMed

Gross, R; Auslitz, J; Schramel, P; Payer, H D

1987-01-01

Several species of legumes and varieties of lupins were examined for their heavy metal content in the seeds. Atomic absorption spectrometry was the main analytical tool. Validity and reproducibility of the results was checked by analyzing the same materials at two different laboratories performing the same technique. Additionally, inductively coupled plasma emission spectroscopy was applied. In grains of Lupinus mutabilis which constitute a traditional food in Andean populations, the following contents of heavy metals were determined: 0.10-0.25 microgram/g Cd; 0.5-1.6 microgram/g Pb; 0.10-0.15 microgram/g Hg. Seeds of other legumes contained 0.05-0.35 microgram/g Cd; 0.1-0.2 microgram/g Pb; 0.01-0.04 microgram/g Hg. The high lead content of lupins is easily reduced to one tenth by traditional extraction with boiling water. The mercury content, too, is decreased by this technique. The high manganese content of 1 300-1,400 micrograms/g of Lupinus albus compared to other legumes (25-37 micrograms/g) seems to be characteristic for this species and may be of nutritional significance. The comparison of the heavy metal contents of legume seeds of different origin and variety indicates a complex pattern of environmental and genetic factors that contribute to the specific metal contents of individual harvests. On the level of varieties the environmental factors (climate, soil, geology, agricultural techniques) seem to exhibit more important influences on the specific accumulation of heavy metals than genetic factors. In contrast, on the level of species or genera, the accumulation of heavy metals seems to be dominated by genetic factors rather than by environmental influences.
Concentration of heavy metals in drinking water of different localities in district east Karachi.

PubMed

Jaleel, M A; Noreen, R; Baseer, A

2001-01-01

Several heavy metals are present in drinking water that play important roles in the body provided their level remains within the specified range recommended by WHO. But now due to the industrialization and rapid urbanization, the problems of pollution have surfaced. This study was designed to ascertain the contents of some heavy metals and then their variations if any in drinking water in different localities of district East of Karachi, Pakistan. Drinking water samples were collected from different sources and localities of district East of Karachi. The concentration of the heavy metals i.e. Lead, Arsenic, Copper, Iron, Mercury, Chromium, Manganese, Nickel, Cadmium and Zinc were determined by Atomic Absorption Spectrophotometry. PH was estimated by pH meter. Total dissolved solids (TDS) were calculated by formula. These concentrations of heavy metals, pH and TDS were compared with the standards set by WHO. Concentrations of lead and nickel were found to be significantly elevated as compared to WHO recommended levels in all the three sources of water (Piped water, Hand pump water and Tanker water supply). Chromium was found to be raised in hand pump water. Arsenic and Mercury were not detected in any source of water. Copper, iron, manganese, cadmium and zinc were found to be within the safe limits in all the three sources of water. pH was found to be within the range of WHO recommended level in all the three sources of water. TDS was found to be elevated in hand pump water and tanker water. Concentrations of lead and nickel were found to be significantly elevated as compared to WHO recommended levels in all the three sources of water in district East of Karachi.
Heavy metals and metalloids in the surface sediments of the Xiangjiang River, Hunan, China: distribution, contamination, and ecological risk assessment.

PubMed

Chai, Liyuan; Li, Huan; Yang, Zhihui; Min, Xiaobo; Liao, Qi; Liu, Yi; Men, Shuhui; Yan, Yanan; Xu, Jixin

2017-01-01

Here, we aim to determine the distribution, ecological risk and sources of heavy metals and metalloids in the surface sediments of the Xiangjiang River, Hunan Province, China. Sixty-four surface sediment samples were collected in 16 sites of the Xiangjiang River, and the concentrations of ten heavy metals and metalloids (Mn, Zn, Cr, V, Pb, Cu, As, Ni, Co, and Cd) in the sediment samples were investigated using an inductively coupled plasma mass spectrometer (ICP-MS) and an atomic fluorescence spectrophotometer (AFS), respectively. The results showed that the mean concentrations of the ten heavy metals and metalloids in the sediment samples followed the order Mn > Zn > Cr > V > Pb > Cu > As ≈ Ni >Co > Cd. The geoaccumulation index (I geo ), enrichment factor (EF), modified degree of contamination (mC d ), and potential ecological risk index (RI) revealed that Cd, followed by Pb, Zn, and Cu, caused severely contaminated and posed very highly potential ecological risk in the Xiangjiang River, especially in Shuikoushan of Hengyang, Xiawan of Zhuzhou, and Yijiawan of Xiangtan. The Pearson's correlation coefficient (PCC) analysis, principal component analysis (PCA), and hierarchical cluster analysis (HCA) indicated that the ten heavy metals and metalloids in the sampling sediments of the Xiangjiang River were classified into three groups: (1) Cd, Pb, Zn, and Cu which possibly originated from Shuikoushan, Xiawan, and Yijiawan clustering Pb-Zn mining and smelting industries; (2) Co, V, Ni, Cr, and Al from natural resources; and (3) Mn and As. Therefore, our results suggest that anthropogenic activities, especially mining and smelting, have caused severe contamination of Cd, Pb, Zn, and Cu and posed very high potential ecological risk in the Xiangjiang River.
Heavy-metal contamination on training ranges at the Grafenwoehr Training Area, Germany

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

Zellmer, S.D.; Schneider, J.F.

1993-05-01

Large quantities of lead and other heavy metals are deposited in the environment of weapons ranges during training exercises. This study was conducted to determine the type, degree, and extent of heavy-metal contamination on selected handgun, rifle, and hand-grenade ranges at Grafenwoehr Training Area, Germany. Soil, vegetation, and surface-water samples were collected and analyzed using the inductively-coupled plasma atomic-emission spectroscopy (ICP-AES) method and the toxic characterization leaching procedure (TCLP). The ICP-AES results show that above-normal levels of lead and copper are in the surface soil at the handgun range, high concentrations of lead and copper are in the berm andmore » soil surface at the rifle range, and elevated levels of cadmium and above-normal concentrations of arsenic, copper, and zinc are present in the surface soil at the hand-grenade range. The TCLP results show that surface soils can be considered hazardous waste because of lead content at the rifle range and because of cadmium concentration at the hand-grenade range. Vegetation at the handgun and rifle ranges has above-normal concentrations of lead. At the hand-grenade range, both vegetation and surface water have high levels of cadmium. A hand-held X-ray fluorescence (XRF) spectrum analyzer was used to measure lead concentrations in soils in a field test of the method. Comparison of XRF readings with ICP-AES results for lead indicate that the accuracy and precision of the hand-held XRF unit must improve before the unit can be used as more than a screening tool. Results of this study show that heavy-metal contamination at all three ranges is limited to the surface soil; heavy metals are not being leached into the soil profile or transported into adjacent areas.« less
Army’s Management of Gray Eagle Spare Parts Needs Improvement (REDACTED)

DTIC Science & Technology

2016-04-29

contracting officers purchased Heavy Fuel Engine 2.0 Liter Turbochargers at an average unit cost of for a total value of General Atomics proposed...Liter Turbocharger to establish an accurate baseline and could potentially overpay on future contracts. See Figure 10 for a picture of the Heavy...Fuel Engine 2.0 Liter Turbocharger . 19 Federal Acquisition Regulation 15.402, “Pricing Policy,” May 29, 2014. 20 Federal Acquisition Regulation 15.404
Failla Memorial lecture. The future of heavy-ion science in biology and medicine.

PubMed

Tobias, C A

1985-07-01

Interplanetary space contains fluxes of fast moving atomic nuclei. The distribution of these reflects the atomic composition of the universe, and such particles may pose limitations for space flight and for life in space. Over the past 50 years, since the invention of Ernest Lawrence's cyclotron, advances in accelerator technology have permitted the acceleration of charged nuclei to very high velocities. Currently, beams of any stable isotope species up to uranium are available at kinetic energies of several hundred MeV/nucleon at the Berkeley Bevalac. Recently, new areas of particle physics research relating to the mechanisms of spallation and fission have opened up for investigation, and it is now realistic to search for nuclear super-dense states that might be produced in heavy nuclear collisions. The heavy ions hold interest for a broad spectrum of research because of their effectiveness in producing a series of major lesions in DNA along single particle tracks and because of the Bragg depth ionization properties that allow the precise deposition of highly localized doses deep in the human body. Individual heavy ions can also interrupt the continuity of membraneous regions in cells. Heavy ions, when compared to low-LET radiation, have increased effectiveness for mammalian cell lethality, chromosome mutations, and cell transformation. The molecular mechanisms are not completely understood but appear to involve fragmentation and reintegration of DNA. Cells attempt to repair these lesions, and many of the deleterious effects are due to misrepair or misrejoining of DNA. Heavy ions do not require the presence of oxygen for producing their effects, and hypoxic cells in necrotic regions have nearly the same sensitivity as cells in well-oxygenated tissues. Heavy ions are effective in delaying or blocking the cell division process. Heavy ions are also strong enhancers of viral-induced cell transformation, a process that requires integration of foreign DNA. Some cell lines, known to be radioresistant to X rays, have exhibited greater sensitivity to heavy ions. These radiobiological properties, combined with the ability to deliver highly localized internal doses, make accelerated heavy ions potentially important radiotherapeutic tools. Other novel approaches include the utilization of radioactive heavy beams as instant tracers. Heavy-ion radiography and microscopy respond to delicate changes in tissue electron density. Dose localization with helium ions has achieved excellent results for pituitary tumors, tumors adjacent to the spinal cord, and ocular melanomas. We are working on adapting silicon- and neon-ion beams for controlled therapy studies.(ABSTRACT TRUNCATED AT 400 WORDS)

The influence of the Rashba effect

NASA Astrophysics Data System (ADS)

Stranks, Samuel D.; Plochocka, Paulina

2018-05-01

Heavy atoms and crystal or inversion symmetry breaking may promote Rashba effects in halide perovskites. Sam Stranks and Paulina Plochocka propose experiments to assess the existence of these effects and their implications on the photophysics of perovskites.
[Particle size determination by radioisotope x-ray absorptiometry with sedimentation method].

PubMed

Matsui, Y; Furuta, T; Miyagawa, S

1976-09-01

The possibility of radioisotope X-ray absorptiometry to determine the particle size of powder in conjunction with sedimentation was investigated. The experimental accuracy was primarily determined by Cow and X-ray intensity. where Co'=weight concentration of the particle in the suspension w'=(micron/rho)l/(mu/rho)s-rhol/rhos rho; density micron/rho; mass absorption coefficient, suffix l and s indicate dispersion and particle, respectively. The radiosiotopes, Fe-55, Pu-238 and Cd-109 have high w-values over the wide range of the atomic number. However, a source of high micron value such as Fe-55 is not suitable because the optimal X-ray transmission length, Lopt is decided by the expression, micronlLopt approximately 2/(1+C'ow') by using Cd-109 AgKX-ray source, the weight size distribution of particles from the heavy elements such as PbO2 to light elements such as Al2O3 or flyash was determined.
Relativistic Zeroth-Order Regular Approximation Combined with Nonhybrid and Hybrid Density Functional Theory: Performance for NMR Indirect Nuclear Spin-Spin Coupling in Heavy Metal Compounds.

PubMed

Moncho, Salvador; Autschbach, Jochen

2010-01-12

A benchmark study for relativistic density functional calculations of NMR spin-spin coupling constants has been performed. The test set contained 47 complexes with heavy metal atoms (W, Pt, Hg, Tl, Pb) with a total of 88 coupling constants involving one or two heavy metal atoms. One-, two-, three-, and four-bond spin-spin couplings have been computed at different levels of theory (nonhybrid vs hybrid DFT, scalar vs two-component relativistic). The computational model was based on geometries fully optimized at the BP/TZP scalar relativistic zeroth-order regular approximation (ZORA) and the conductor-like screening model (COSMO) to include solvent effects. The NMR computations also employed the continuum solvent model. Computations in the gas phase were performed in order to assess the importance of the solvation model. The relative median deviations between various computational models and experiment were found to range between 13% and 21%, with the highest-level computational model (hybrid density functional computations including scalar plus spin-orbit relativistic effects, the COSMO solvent model, and a Gaussian finite-nucleus model) performing best.
Ground-State Hyperfine Structure of Heavy Hydrogen-Like Ions

NASA Astrophysics Data System (ADS)

Kühl, T.; Borneis, S.; Dax, A.; Engel, T.; Faber, S.; Gerlach, M.; Holbrow, C.; Huber, G.; Marx, D.; Merz, P.; Quint, W.; Schmitt, F.; Seelig, P.; Tomaselli, M.; Winter, H.; Wuertz, M.; Beckert, K.; Franzke, B.; Nolden, F.; Reich, H.; Steck, M.

Contributions of quantum electrodynamics (QED) to the combined electric and magnetic interaction between the electron and the nucleus can be studied by optical spectroscopy in high-Z hydrogen-like heavy ions. The transition studied is the ground-state hyperfine structure transition, well known from the 21 cm line in atomic hydrogen. The hyperfine splitting of the is ground state of hydrogen-like systems constitutes the simplest and most basic magnetic interaction in atomic physics. The Z3-increase leads to a transition energy in the UV-region of the optical spectrum for the case of Bi82+. At the same time, the QED correction rises to nearly 1 fraction of higher order contributions. This situation is particularly useful for a comparison with non-perturbative QED calculations. The combination of exceptionally intense electric and magnetic fields electric and magnetic fields is unique. This transition has become accessible to precision laser spectroscopy at the high-energy heavy-ion storage ring at GSI-Darmstadt in the hydrogen-like 209Bi82+ and 207Pb81+. In the meantime, 165Ho66+ and 185,187Re74+ were also studied with reduced resolution by conventional optical spectroscopy at the SuperEBIT ion trap at Lawrence Livermore National Laboratory.
Impact parameter sensitive study of inner-shell atomic processes in the experimental storage ring

NASA Astrophysics Data System (ADS)

Gumberidze, A.; Kozhuharov, C.; Zhang, R. T.; Trotsenko, S.; Kozhedub, Y. S.; DuBois, R. D.; Beyer, H. F.; Blumenhagen, K.-H.; Brandau, C.; Bräuning-Demian, A.; Chen, W.; Forstner, O.; Gao, B.; Gassner, T.; Grisenti, R. E.; Hagmann, S.; Hillenbrand, P.-M.; Indelicato, P.; Kumar, A.; Lestinsky, M.; Litvinov, Yu. A.; Petridis, N.; Schury, D.; Spillmann, U.; Trageser, C.; Trassinelli, M.; Tu, X.; Stöhlker, Th.

2017-10-01

In this work, we present a pilot experiment in the experimental storage ring (ESR) at GSI devoted to impact parameter sensitive studies of inner shell atomic processes for low-energy (heavy-) ion-atom collisions. The experiment was performed with bare and He-like xenon ions (Xe54+, Xe52+) colliding with neutral xenon gas atoms, resulting in a symmetric collision system. This choice of the projectile charge states was made in order to compare the effect of a filled K-shell with the empty one. The projectile and target X-rays have been measured at different observation angles for all impact parameters as well as for the impact parameter range of ∼35-70 fm.
Selected bibliography on atomic collisions: Data collections, bibliographies, review articles, books, and papers of particular tutorial value

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

McDaniel, E.W.; Flannery, M.R.; Thomas, E.W.

This bibliography deals mainly with binary and ternary collisions involving electrons, photons, and heavy particles (i.e., atoms, molecules, and ions). The energy range covered for each kind of collision is such that the interactions might be described as electronic, atomic, or chemical--higher-energy collisions involving nuclear forces are not treated. Also covered are particle and photon impact on surfaces, the passage of particles and radiation through bulk matter, and transport phenomena in gases. Practically all of the references cited are data compilations, other bibliographies, review articles, or books. The main objective is to provide easy access to atomic collision data, althoughmore » some references are included principally for their tutorial value.« less
Biological consequences of nanoscale energy deposition near irradiated heavy atom nanoparticles

PubMed Central

McMahon, Stephen J.; Hyland, Wendy B.; Muir, Mark F.; Coulter, Jonathan A.; Jain, Suneil; Butterworth, Karl T.; Schettino, Giuseppe; Dickson, Glenn R.; Hounsell, Alan R.; O'Sullivan, Joe M.; Prise, Kevin M.; Hirst, David G.; Currell, Fred J.

2011-01-01

Gold nanoparticles (GNPs) are being proposed as contrast agents to enhance X-ray imaging and radiotherapy, seeking to take advantage of the increased X-ray absorption of gold compared to soft tissue. However, there is a great discrepancy between physically predicted increases in X-ray energy deposition and experimentally observed increases in cell killing. In this work, we present the first calculations which take into account the structure of energy deposition in the nanoscale vicinity of GNPs and relate this to biological outcomes, and show for the first time good agreement with experimentally observed cell killing by the combination of X-rays and GNPs. These results are not only relevant to radiotherapy, but also have implications for applications of heavy atom nanoparticles in biological settings or where human exposure is possible because the localised energy deposition high-lighted by these results may cause complex DNA damage, leading to mutation and carcinogenesis. PMID:22355537
Molecular vibrational energy flow

NASA Astrophysics Data System (ADS)

Gruebele, M.; Bigwood, R.

This article reviews some recent work in molecular vibrational energy flow (IVR), with emphasis on our own computational and experimental studies. We consider the problem in various representations, and use these to develop a family of simple models which combine specific molecular properties (e.g. size, vibrational frequencies) with statistical properties of the potential energy surface and wavefunctions. This marriage of molecular detail and statistical simplification captures trends of IVR mechanisms and survival probabilities beyond the abilities of purely statistical models or the computational limitations of full ab initio approaches. Of particular interest is IVR in the intermediate time regime, where heavy-atom skeletal modes take over the IVR process from hydrogenic motions even upon X H bond excitation. Experiments and calculations on prototype heavy-atom systems show that intermediate time IVR differs in many aspects from the early stages of hydrogenic mode IVR. As a result, IVR can be coherently frozen, with potential applications to selective chemistry.
Impacts of geology and land use on magnetic susceptibility and selected heavy metals in surface soils of Mashhad plain, northeastern Iran

NASA Astrophysics Data System (ADS)

Karimi, Alireza; Haghnia, Gholam Hosain; Ayoubi, Shamsollah; Safari, Tayebeh

2017-03-01

Magnetic susceptibility is a fast, inexpensive and reliable technique for estimating and monitoring the anthropogenic contamination of soil with heavy metals. However, it is essential to determine the factors affecting magnetic susceptibility before applying this technique to environmental studies. The objectives of this study were to investigate i) the effect of parent materials and land use on the magnetic susceptibility and concentrations of Fe, Ni, Pb and Zn, and ii) capability of magnetic susceptibility as an indicator of anthropogenic heavy metals contamination of soil in Mashhad plain, northeastern Iran. One hundred seventy-eight composite surface soil samples (0-10 cm) were taken. The aqua-regia extractable concentrations of Fe, Ni, Zn and Pb were determined by atomic absorption spectroscopy. Magnetic susceptibility at low and high frequency (χlf and χhf) were measured and frequency dependent susceptibility (χfd) was calculated. The average concentrations of Fe, Ni, Pb and Zn were 22,812, 61.4, 74.1 and 31.6 mg kg- 1, respectively. The highest contents of Pb (69.1 mg kg- 1) and Zn (149 mg kg- 1) were observed in urban area. The highest concentration of Ni was 41,538 mg kg- 1 observed in the soils developed from ultramafic rocks. Magnetic susceptibility varied from 20.3 on marly sediments to 311.8 × 10- 8 m3 kg- 1 on ultramafic rocks. A positive strong correlation (Pvalue < 0.01, r = 0.88) was obtained between Ni and χlf. There were no significant relationships between Zn and Pb with χlf, therefore it seems that magnetic susceptibility has not been affected significantly by anthropogenic activities which enhanced Pb and Zn concentrations in urban soils. The results indicated that magnetic susceptibility was mainly controlled by Ni containing minerals with lithogenic origin. Therefore, in the soils studied, magnetic susceptibility could not be employed as indicator of anthropogenic contamination of soil with heavy metals.
Nuclear-bound quarkonia and heavy-flavor hadrons

NASA Astrophysics Data System (ADS)

Krein, G.; Thomas, A. W.; Tsushima, K.

2018-05-01

In our quest to win a deeper understanding of how QCD actually works, the study of the binding of heavy quarkonia and heavy-flavor hadrons to atomic nuclei offers enormous promise. Modern experimental facilities such as FAIR, Jefferson Lab at 12 GeV and J-PARC offer exciting new experimental opportunities to study such systems. These experimental advances are complemented by new theoretical approaches and predictions, which will both guide these experimental efforts and be informed and improved by them. This review will outline the main theoretical approaches, beginning with QCD itself, summarize recent theoretical predictions and relate them both to past experiments and those from which we may expect results in the near future.
The interaction of excited He, Ar and Ne metastable atoms with the CF2Cl2 molecule

NASA Astrophysics Data System (ADS)

Cherid, M.; Ben Arfa, M.; Driss Khodja, M.

2004-02-01

We studied Penning ionization of the CF2Cl2 molecule by neon and helium metastable atoms. In the case of the neon ionizing particle, we measured the electron kinetic energy as well as mass spectra; for helium metastable atoms, only the mass spectrum was recorded. We, therefore, obtained the branching ratios for the heavy charged particles produced in both interactions. In this report we will discuss the mechanism involved in the production of metastable halogen atoms in the dielectric barrier discharge further to the use of rare gases/CF2Cl2 mixtures. We show that this process needs a two-stage reaction. Ground state free halogen atoms are formed over the first stage by Penning ionization, charge transfer, dissociate excitation and ionization. Therefore, metastable halogen atoms can be produced by excitation transfer process in the second stage through interaction with metastable rare gas atoms. This paper is dedicated to Professor F M E Tuffin on the occasion of his retirement.
An attempt for modeling the atmospheric transport of 3H around Kakrapar Atomic Power Station.

PubMed

Patra, A K; Nankar, D P; Joshi, C P; Venkataraman, S; Sundar, D; Hegde, A G

2008-01-01

Prediction of downwind tritium air concentrations in the environment around Kakrapar Atomic Power Station (KAPS) was studied on the basis of Gaussian plume dispersion model. The tritium air concentration by field measurement [measured tritium air concentrations in the areas adjacent to KAPS] were compared with the theoretically calculated values (predicted) to validate the model. This approach will be useful in evaluating environmental radiological impacts due to pressurised heavy water reactors.
Molecular dynamics study of structural damage in amorphous silica induced by swift heavy-ion radiation

NASA Astrophysics Data System (ADS)

Zhen, J. S.; Yang, Q.; Yan, Y. H.; Jiang, X. W.; Yan, S. A.; Chen, W.; Guo, X. Q.

2016-03-01

In this paper, the radiation defects induced by the swift heavy ions and the recoil atoms in amorphous SiO2 were studied. The energy of recoil atoms induced by the incident Au ions in SiO2 was calculated by using Monte Carlo method. Results show that the average energies of recoils reach the maximum (200 eV for Si and 130 eV for O, respectively) when the incident energy of Au ion is 100 MeV. Using Tersoff/zbl potential with the newly built parameters, the defects formation processes in SiO2 induced by the recoils were studied by using molecular dynamics method. The displacement threshold energies (Ed) for Si and O atoms are found to be 33.5 and 16.3 eV, respectively. Several types of under- and over-coordinated Si and O defects were analyzed. The results demonstrate that Si3, Si5, and O1 are the mainly defects in SiO2 after radiation. Besides, the size of cylindrical damage region produced by a single recoil atom was calculated. The calculation shows that the depth and the radius are up to 2.0 and 1.4 nm when the energy of recoils is 200 eV. Finally, it is estimated that the Au ion would induce a defected track with a diameter of 4 nm in SiO2.
Trace elements and heavy metals in mineral and bottled drinking waters on the Iranian market.

PubMed

Hadiani, Mohammad Rasoul; Dezfooli-Manesh, Shirin; Shoeibi, Shahram; Ziarati, Parisa; Mousavi Khaneghah, Amin

2015-01-01

A survey of Iranian waters, sampled from 2010 to 2013, is presented. A total of 128 water samples from 42 different brands of bottled mineral and drinking water were collected and analysed for contamination levels of lead (Pb), cadmium (Cd), copper (Cu), arsenic (As) and mercury (Hg). Determinations were performed using a graphite furnace atomic absorption spectrophotometer for Pb, Cd and Cu, a hydride vapour generation as well as an Arsenator digital kit (Wagtech WTD, Tyne and Wear, UK) for As and a direct mercury analyser for Hg. Arsenic concentration in six bottled gaseous mineral samples was higher than the related limit. Regardless of these, mean concentrations of Pb, Cd, Cu, As and Hg in all types of water samples were 4.50 ± 0.49, 1.08 ± 0.09, 16.11 ± 2.77, 5.80 ± 1.63 and 0.52 ± 0.03 µg L⁻¹, respectively. Values obtained for analysed heavy metals in all samples were permissible according to the limits of national and international standards.
Determination of elements in ayurvedic medicinal plants by AAS

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

Teerthe, Santoshkumar S.; Kerur, B. R., E-mail: kerurbrk@yahoo.com

India has a rich country for the uses of Ayurvedic medicinal plants for treatment and also the north- Karnataka boasts an unparallel diversity of medicinal plants. The present study attempts to estimate and compare the level of trace and heavy metals in some selected leaves and root samples of Ayurvedic medicinal plants such as Mg, Al, K, Cr, Mn, Fe, Cu, Zn, and Cd. The samples are collected from different places of North-Karnataka regions and sample solutions prepared as the ratio of 1:25:25+950ml=1000ppm.the trace and heavy elemental concentration was estimated using Atomic Absorption Spectrometric (AAS) Method. The average concentrations ofmore » Mg, Mn, Fe and Zn, are ranging from 2ppm to 5250.2ppm and potassium (K) has more concentration as compare to all other. The other elements likes Al, Cr, Cu, and Cd were also estimed and presented in the table. Therefore, these medicinal plants are rich in some essential minerals, especially K, Mg, Mn, Fe and Zn which are essential for human health.« less
Analyses of heavy metals in mineral trioxide aggregate and Portland cement.

PubMed

Schembri, Matthew; Peplow, George; Camilleri, Josette

2010-07-01

Portland cement is used in the construction industry as a binder in concrete. It is manufactured from chalk, limestone, and clay, which are clinkered at very high temperatures and ground with gypsum to form Portland cement. The raw materials and the manufacturing process can result in the inclusion of heavy metals in Portland cement. Portland cement with a four to one addition of bismuth oxide is marketed as mineral trioxide aggregate (MTA), which is used mainly as a dental material. Heavy metal inclusion can be of concern because MTA is in contact with hard and soft tissues. Measurements of arsenic, lead, and chromium in hydrated gray and white Portland cement, ProRoot MTA, and MTA Angelus were conducted with graphite furnace atomic absorption spectrophotometry after acid digestion on the hydrated material. The leaching of the metal ions from the solid material in water and simulated body fluid (SBF) was also determined. All cement types showed high relative values of leached chromium compared with arsenic and lead in both the total metal content and leached species. The gray Portland cement showed the highest total amount of metal. The white Portland and both MTAs had lower values for all the leached metal ions. Both MTAs released more arsenic than the amount specified in ISO 9917-1 (2007). Portland cements and MTAs showed evidence of heavy metals in the acid-soluble form as well as leaching in deionized water and SBF. MTA contained levels of arsenic higher than the safe limit specified by the ISO 9917-1 (2007). Copyright 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.
Scalar relativistic computations of nuclear magnetic shielding and g-shifts with the zeroth-order regular approximation and range-separated hybrid density functionals

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

Aquino, Fredy W.; Govind, Niranjan; Autschbach, Jochen

2011-10-01

Density functional theory (DFT) calculations of NMR chemical shifts and molecular g-tensors with Gaussian-type orbitals are implemented via second-order energy derivatives within the scalar relativistic zeroth order regular approximation (ZORA) framework. Nonhybrid functionals, standard (global) hybrids, and range-separated (Coulomb-attenuated, long-range corrected) hybrid functionals are tested. Origin invariance of the results is ensured by use of gauge-including atomic orbital (GIAO) basis functions. The new implementation in the NWChem quantum chemistry package is verified by calculations of nuclear shielding constants for the heavy atoms in HX (X=F, Cl, Br, I, At) and H2X (X = O, S, Se, Te, Po), and Temore » chemical shifts in a number of tellurium compounds. The basis set and functional dependence of g-shifts is investigated for 14 radicals with light and heavy atoms. The problem of accurately predicting F NMR shielding in UF6-nCln, n = 1 to 6, is revisited. The results are sensitive to approximations in the density functionals, indicating a delicate balance of DFT self-interaction vs. correlation. For the uranium halides, the results with the range-separated functionals are mixed.« less
Rashba spin-orbit coupling and orbital chirality in magnetic bilayers

NASA Astrophysics Data System (ADS)

Lee, Hyun-Woo

2013-03-01

The phenomenon of the Rashba spin-orbit coupling is examined theoretically for an ultrathin magnetic layer in contact with a non-magnetic heavy metal layer. From first-principles calculation, large Rashba parameter of order 1 eV .Å is obtained, which is strong enough to generate large spin transfer torque of spin-orbit coupling origin. Large Rashba parameter is attributed to the orbital mixing of 3 d magnetic atoms and non-magnetic heavy elements with significant atomic spin-orbit coupling. Interestingly the magnitude and sign of the parameter vary from energy bands to bands, which we attribute to band-specific chiral ordering of orbital angular momentum. Through a simple tight-binding model analysis, we demonstrate that d-orbital hybridization allowed by the breaking of structural inversion symmetry generates band-specific chiral ordering of orbital angular momentum, which combines with atomic spin-orbit coupling to give rise to band-specific Rashba parameter. The band-dependence of the Rashba parameter is discussed in connection with recent experiments and we argue that the dependence may be utilized to enhance device application potentials. This work is supported by NRF grant (2010-0008529, 2011-0015631, 2010-0014109, 2011-0030789).
Near-threshold photoionization of hydrogenlike uranium studied in ion-atom collisions via the time-reversed process.

PubMed

Stöhlker, T; Ma, X; Ludziejewski, T; Beyer, H F; Bosch, F; Brinzanescu, O; Dunford, R W; Eichler, J; Hagmann, S; Ichihara, A; Kozhuharov, C; Krämer, A; Liesen, D; Mokler, P H; Stachura, Z; Swiat, P; Warczak, A

2001-02-05

Radiative electron capture, the time-reversed photoionization process occurring in ion-atom collisions, provides presently the only access to photoionization studies for very highly charged ions. By applying the deceleration mode of the ESR storage ring, we studied this process in low-energy collisions of bare uranium ions with low- Z target atoms. This technique allows us to extend the current information about photoionization to much lower energies than those accessible for neutral heavy elements in the direct reaction channel. The results prove that for high- Z systems, higher-order multipole contributions and magnetic corrections persist even at energies close to the threshold.
Is the Lamb shift chemically significant?

NASA Technical Reports Server (NTRS)

Dyall, Kenneth G.; Bauschlicher, Charles W., Jr.; Schwenke, David W.; Pyykko, Pekka; Arnold, James (Technical Monitor)

2001-01-01

The contribution of the Lamb shift to the atomization energies of some prototype molecules, BF3, AlF3, and GaF3, is estimated by a perturbation procedure. It is found to be in the range of 3-5% of the one-electron scalar relativistic contribution to the atomization energy. The maximum absolute value is 0.2 kcal/mol for GaF3. These sample calculations indicate that the Lamb shift is probably small enough to be neglected for energetics of molecules containing light atoms if the target accuracy is 1 kcal/mol, but for higher accuracy calculations and for molecules containing heavy elements it must be considered.

Effects of Ion Atomic Number on Single-Event Gate Rupture (SEGR) Susceptibility of Power MOSFETs

NASA Technical Reports Server (NTRS)

Lauenstein, J.-M.; Goldsman, N.; Liu, S.; Titus, J.; Ladbury, R. L.; Kim, H. S.; Phan, A. M.; Zafrani, M.; Sherman, P.

2011-01-01

The relative importance of heavy-ion interaction with the oxide, charge ionized in the epilayer, and charge ionized in the drain substrate, on the bias for SEGR failure is experimentally investigated.
Speciation, sources, and risk assessment of heavy metals in suburban vegetable garden soil in Xianyang City, Northwest China

NASA Astrophysics Data System (ADS)

Wang, Lijun; Tao, Wendong; Smardon, Richard C.; Xu, Xue; Lu, Xinwei

2017-07-01

Intensive anthropogenic activities can lead to soil heavy metal contamination resulting in potential risks to the environment and to human health. To reveal the concentrations, speciation, sources, pollution level, and ecological risk of heavy metals in vegetable garden soil, a total of 136 soil samples were collected from three vegetable production fields in the suburbs of Xianyang City, Northwest China. These samples were analyzed by inductively coupled plasma- atomic emission spectrometry and atomic fluorescence spectrometry. The results showed that the mean concentrations of Cd, Co, Cu, Mn, Pb, Zn, and Hg in vegetable garden soil were higher than the corresponding soil element background values of Shaanxi Province. The heavy metals studied in vegetable garden soil were primarily found in the residual fraction, averaging from 31.26% (Pb) to 90.23% (Cr). Considering the non-residual fractions, the mobility or potential risk was in the order of Pb (68.74%)>Co (60.54%)>Mn (59.28%) >Cd (53.54%) ≫Ni (23.36%) >Zn (22.73%)>Cu (14.93%)>V (11.81%)>Cr (9.78%). Cr, Mn, Ni, V, and As in the studied soil were related to soilforming parent materials, while Cu, Hg, Zn, Cd, Co, and Pb were associated with the application of plastic films, fertilizers, and pesticides, as well as traffic emissions and industrial fumes. Cr, Ni, V, and As presented low contamination levels, whereas Co, Cu, Mn, Pb, and Zn levels were moderate, and Cd and Hg were high. Ecological risk was low for Co, Cr, Cu, Mn, Pb, Zn, and As, with high risk observed for Cd and Hg. The overall pollution level and ecological risk of these heavy metals were high.
Speciation, sources, and risk assessment of heavy metals in suburban vegetable garden soil in Xianyang City, Northwest China

NASA Astrophysics Data System (ADS)

Wang, Lijun; Tao, Wendong; Smardon, Richard C.; Xu, Xue; Lu, Xinwei

2018-06-01

Intensive anthropogenic activities can lead to soil heavy metal contamination resulting in potential risks to the environment and to human health. To reveal the concentrations, speciation, sources, pollution level, and ecological risk of heavy metals in vegetable garden soil, a total of 136 soil samples were collected from three vegetable production fields in the suburbs of Xianyang City, Northwest China. These samples were analyzed by inductively coupled plasma- atomic emission spectrometry and atomic fluorescence spectrometry. The results showed that the mean concentrations of Cd, Co, Cu, Mn, Pb, Zn, and Hg in vegetable garden soil were higher than the corresponding soil element background values of Shaanxi Province. The heavy metals studied in vegetable garden soil were primarily found in the residual fraction, averaging from 31.26% (Pb) to 90.23% (Cr). Considering the non-residual fractions, the mobility or potential risk was in the order of Pb (68.74%)>Co (60.54%)>Mn (59.28%) >Cd (53.54%) ≫Ni (23.36%) >Zn (22.73%)>Cu (14.93%)>V (11.81%)>Cr (9.78%). Cr, Mn, Ni, V, and As in the studied soil were related to soilforming parent materials, while Cu, Hg, Zn, Cd, Co, and Pb were associated with the application of plastic films, fertilizers, and pesticides, as well as traffic emissions and industrial fumes. Cr, Ni, V, and As presented low contamination levels, whereas Co, Cu, Mn, Pb, and Zn levels were moderate, and Cd and Hg were high. Ecological risk was low for Co, Cr, Cu, Mn, Pb, Zn, and As, with high risk observed for Cd and Hg. The overall pollution level and ecological risk of these heavy metals were high.
Isolation and characterization of Bacillus cereus IST105 from electroplating effluent for detoxification of hexavalent chromium.

PubMed

Naik, Umesh Chandra; Srivastava, Shaili; Thakur, Indu Shekhar

2011-08-01

Electroplating industries are the main sources of heavy metals, chromium, nickel, lead, zinc, cadmium and copper. The highest concentrations of chromium (VI) in the effluent cause a direct hazards to human and animals. Therefore, there is a need of an effective and affordable biotechnological solution for removal of chromium from electroplating effluent. Bacterial strains were isolated from electroplating effluent to find out higher tolerant isolate against chromate. The isolate was identified by 16S rDNA sequence analysis. Absorbed chromium level of bacterium was determined by inductively coupled plasma-atomic emission spectrometer (ICP-AES), atomic absorption spectrophotometer (AAS), scanning electron microscope (SEM), transmission electron microscope (TEM) and energy dispersive X-ray analysis (EDX). Removal of metals by bacterium from the electroplating effluent eventually led to the detoxification of effluent confirmed by MTT assay. Conformational changes of functional groups of bacterial cell surface were studied through Fourier transform infrared spectroscopy. The chromate tolerant isolate was identified as Bacillus cereus. Bacterium has potency to remove more than 75% of chromium as measured by ICP-AES and AAS. The study indicated the accumulation of chromium (VI) on bacterial cell surface which was confirmed by the SEM-EDX and TEM analysis. The biosorption of metals from the electroplating effluent eventually led to the detoxification of effluent. The increased survivability of Huh7 cells cultured with treated effluent also confirmed the detoxification as examined by MTT assay. Isolated strain B. cereus was able to remove and detoxify chromium (VI). It would be an efficient tool of the biotechnological approach in mitigating the heavy metal pollutants.
Do fattening process and biological parameters affect the accumulation of metals in Atlantic bluefin tuna?

PubMed

Milatou, Niki; Dassenakis, Manos; Megalofonou, Persefoni

2015-01-01

The objective of this study was to determine the current levels of heavy metals and trace elements in Atlantic bluefin tuna muscle tissues and how they are influenced by the fattening process and various life history parameters to ascertain whether the concentrations in muscle tissue exceed the maximum levels defined by the European Commission Decision and to evaluate the health risk posed by fish consumption. A total of 20 bluefin tuna reared in sea cages, ranging from 160 to 295 cm in length and from 80 to 540 kg in weight, were sampled from a bluefin tuna farm in the Ionian Sea. The condition factor K of each specimen was calculated and their age was estimated. Heavy metal and trace element (Hg, Zn, Fe and Cu) contents were determined in muscle tissue using cold vapour atomic absorption spectrometry and flame and graphite furnace atomic absorption spectrometry. The total Hg concentrations ranged from 0.28 to 1.28 mg kg(-1) w/w, Zn from 5.81 to 76.37 mg kg(-1) w/w, Fe from 12.14 to 39.58 mg kg(-1) w/w, and Cu from 0.36 to 0.94 mg kg(-1) w/w. Only 5% of the muscle samples of tuna contained Hg above the maximum level laid down by the European Commission Decision. Moreover, 15% of the muscle samples contained Zn above the maximum level, while Fe and Cu concentrations were within the acceptable tolerable guideline values. The reared bluefin tuna had lower concentrations of Hg than the wild ones from the Mediterranean Sea. Hg and Fe concentrations showed a positive relationship with size and age of bluefin tuna, whereas negative relationships were found for the concentrations of Zn and Cu. The estimated dietary intake values of the analysed metals were mostly below the derived guidelines.
Determination and Quantification of metals in the shells of Crassostrea virginica after the Deepwater Horizon oil spill utilizing Atomic Absorption Spectrometry.

NASA Astrophysics Data System (ADS)

Roopnarine, D.; Patel, S.; Roopnarine, P.; Giarikos, D.; Anderson, L. C.

2017-12-01

The Deepwater Horizon (DWH) oil rig explosion on April 20, 2010 resulted in the release of 685,000 tons of crude oil into the Gulf of Mexico (GOM) over a period of three months. There were obvious immediate effects, but the long-term ramifications are still being studied. The primary constituent of crude oil is hydrocarbons with other organic compounds containing nitrogen, oxygen and sulfur. There are also a number of trace metals with the most abundant frequently being iron, nickel, copper and vanadium. These do not degrade like organic materials. However, the exact composition varies among the production sites. The oil from the DWH rig was classified as light crude which is moderately volatile. Natural oil seeps occur in the environment, but the DWH spill represented an acute impact. Trace amounts of heavy metals are a normal part of the composition of marine organisms, but can be toxic in high concentrations. Bivalved molluscs bioaccumulate heavy metals in their tissues and shells, and are therefore often useful as monitors of environmental pollution. We thus used the Eastern oyster Crassostrea virginica to determine the impact of the spill by measuring the concentrations of metals in the shells utilizing flame emission atomic absorption spectrometry. We focused on the hypothesis that DWH spill exposure resulted in an increase in metal uptake into the shells. Specimens spanned the years 2010 to 2014 and ranged from Grand Isle, LA to Apalachicola Bay, Fl. Vanadium had the greatest concentration in the shells, and along with copper, cadmium, zinc and iron displayed an upward trend of increase from 2010 to 2013, with a decline in 2014. However there was unexpected variability, as the specimens from Apalachicola Bay, Fl had higher levels of vanadium when compared to those from Grand Isle, LA. Ongoing work includes an increase of sample sizes from the same geographic localities and time period.
Study of MoNbO(y) (y = 2-5) anion and neutral clusters using photoelectron spectroscopy and density functional theory calculations: impact of spin contamination on single point calculations.

PubMed

Waller, Sarah E; Mann, Jennifer E; Rothgeb, David W; Jarrold, Caroline C

2012-10-04

Results of a study combining anion photoelectron spectroscopy and density functional theory calculations on the heteronuclear MoNbO(y)(-) (y = 2-5) transition metal suboxide cluster series are reported and analyzed. The photoelectron spectra, which exhibit broad electronic bands with partially resolved vibrational structure, were compared to spectral simulations generated from calculated spectroscopic parameters for all computationally determined energetically competitive structures. Although computational results on the less oxidized clusters could not be satisfactorily reconciled with experimental spectra, possibly because of heavy spin contamination found in a large portion of the computational results, the results suggest that (1) neutral cluster electron affinity is a strong indicator of whether O-atoms are bound in M-O-M bridge positions or M═O terminal positions, (2) MoNbO(y) anions and neutrals have structures that can be described as intermediate with respect to the unary (homonuclear) Mo(2)O(y) and Nb(2)O(y) clusters, and (3) structures in which O-atoms preferentially bind to the Nb center are slightly more stable than alternative structures. Several challenges associated with the calculations are considered, including spin contamination, which appears to cause spurious single point calculations used to determine vertical detachment energies.
Health risks associated with heavy metals in the drinking water of Swat, northern Pakistan.

PubMed

Lu, Yonglong; Khan, Hizbullah; Zakir, Shahida; Ihsanullah; Khan, Sardar; Khan, Akbar Ali; Wei, Luo; Wang, Tieyu

2013-10-01

The concentrations of heavy metals such as Cd, Cr, Cu, Mn, Ni, Pb and Zn were investigated in drinking water sources (surface and groundwater) collected from Swat valley, Khyber Pakhtunkhwa, Pakistan. The potential health risks of heavy metals to the local population and their possible source apportionment were also studied. Heavy metal concentrations were analysed using atomic absorption spectrometer and compared with permissible limits set by Pakistan Environmental Protection Agency and World Health Organization. The concentrations of Cd, Cr, Ni and Pb were higher than their respective permissible limits, while Cu, Mn and Zn concentrations were observed within their respective limits. Health risk indicators such as chronic daily intake (CDI) and health risk index (HRI) were calculated for adults and children separately. CDIs and HRIs of heavy metals were found in the order of Cr > Mn > Ni > Zn > Cd > Cu > Pb and Cd > Ni > Mn > Cr > Cu > Pb > Zn, respectively. HRIs of selected heavy metals in the drinking water were less than 1, indicating no health risk to the local people. Multivariate and univariate statistical analyses showed that geologic and anthropogenic activities were the possible sources of water contamination with heavy metals in the study area.
Analysis of heavy metal lead (Pb) levels with Aas in cow's milk by giving cumin (Cuminum cyminum L.), white turmeric (Curcuma zedoaria Rosc.) and mango turmeric (Curcuma mangga Val.).

PubMed

Nurdin, E; Putra, D P; Amelia, T

2013-11-01

The aim of this study was to determine the effect of giving Cumin (Cuminum cyminum L.), White Turmeric (Curcuma zedoaria Rosc.) and Mango Turmeric (Curcuma mango Val.) on levels of heavy metals lead (Pb) in cow's milk produced. The study was conducted in West Java with experimental method in 16 Fries Holland dairy cows with lactation period of 2-4 months and lactation months of 3-4 months. The design used is simple randomized design with 4 treatments such as Group A (control/no treatment), Group B (Cumin 0.03% body weight), Group C (White Turmeric 0.02% body weight) and Group D (Mango Turmeric 0.06% body weight). Measurement of Pb levels in milk using the method of wet destruction, while Pb measurements on faeces using wet ashing method, by means of Atomic Absorption Spectrophotometry. Based on the researsch results showed that administration of Cumin, White Turmeric and Mango Turmeric have very real effect on reducing levels of heavy metals lead (Pb) in cow's milk produced, with a consecutive decrease 98.36, 99.33 and 99.37% and the very real effect on elevated levels of Pb in faeces by 68.01, 64.52 and 80.54%. Mango Turmeric is the best treatment of three treatment in decreasing lead level in milk.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Pacheco, J. L.; Singh, M.; Perry, D. L.

Here, we demonstrate a capability of deterministic doping at the single atom level using a combination of direct write focused ion beam and solid-state ion detectors. The focused ion beam system can position a single ion to within 35 nm of a targeted location and the detection system is sensitive to single low energy heavy ions. This platform can be used to deterministically fabricate single atom devices in materials where the nanostructure and ion detectors can be integrated, including donor-based qubits in Si and color centers in diamond.
The pair-production channel in atomic processes

NASA Astrophysics Data System (ADS)

Belkacem, Ali; Sørensen, Allan H.

2006-06-01

Assisted by the creation of electron-positron pairs, new channels for ionization, excitation, and charge transfer open in atomic collisions when the energy is raised to relativistic values. At extreme energies these pair-production channels usually dominate the "traditional" contributions to cross sections that involve only "positive-energy" electrons. An extensive body of theoretical and experimental work has been performed over the last two decades to investigate charge-changing processes catalyzed by pair production in relativistic heavy ion collisions. We review some of these studies.
Photoionization and pseudopotentials

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

Costa, Romarly F. da; Lima, Marco A.P.; Ferreira, Luiz G.

2003-05-01

Transferability of norm-conserving pseudopotentials to low-energy electron-molecule scattering processes has been very successful [Bettega et al., Phys. Rev. A 47, 1111 (1993)]. In this paper we discuss the possibility of using effective potentials in calculations of valence electrons photoionization cross sections. Through atomic targets, we illustrate that pseudopotentials can be optimized to give cross sections in good agreement with all-electron calculations. The present work represents a first step towards more elaborate computer programs for photoionization of molecular targets containing heavy atoms.
Thermoelectric materials with filled skutterudite structure for thermoelectric devices

NASA Technical Reports Server (NTRS)

Fleurial, Jean-Pierre (Inventor); Borshchevsky, Alex (Inventor); Caillat, Thierry (Inventor); Morelli, Donald T. (Inventor); Meisner, Gregory P. (Inventor)

2002-01-01

A class of thermoelectric compounds based on the skutterudite structure with heavy filling atoms in the empty octants and substituting transition metals and main-group atoms. High Seebeck coefficients and low thermal conductivities are achieved in combination with large electrical conductivities in these filled skutterudites for large ZT values. Substituting and filling methods are disclosed to synthesize skutterudite compositions with desired thermoelectric properties. A melting and/or sintering process in combination with powder metallurgy techniques is used to fabricate these new materials.
Thermoelectric devices based on materials with filled skutterudite structures

NASA Technical Reports Server (NTRS)

Fleurial, Jean-Pierre (Inventor); Borshchevsky, Alex (Inventor); Caillat, Thierry (Inventor); Morelli, Donald T. (Inventor); Meisner, Gregory P. (Inventor)

2003-01-01

A class of thermoelectric compounds based on the skutterudite structure with heavy filling atoms in the empty octants and substituting transition metals and main-group atoms. High Seebeck coefficients and low thermal conductivities are achieved in combination with large electrical conductivities in these filled skutterudites for large ZT values. Substituting and filling methods are disclosed to synthesize skutterudite compositions with desired thermoelectric properties. A melting and/or sintering process in combination with powder metallurgy techniques is used to fabricate these new materials.
Limestone-based technosols: a suitable way for the remediation of sediments contaminated by heavy metals.

NASA Astrophysics Data System (ADS)

Martínez-Sanchez, Maria Jose; Garcia-Lorenzo, Mari Luz; Martínez, Salvadora; Gonzalez, Eva; Molina, Jose; Hernández, Carmen; Pérez-Sirvent, Carmen

2013-04-01

The aim of this work was to assess the suitability of limestone-based technosols for decreasing the toxicity of the leachates caused by rain in sites contaminated by heavy metals. For such a purpose, 64 technosols were prepared in containers of 0.75m3, filled with 4 types of sediments collected from Portman Bay and subjected to different stabilizer proportions (limestone filler), different thickness of a drainage layer and presence/absence of a topsoil cover. The technosols were then submitted to different humidity/dryness cycles simulating the usual rain conditions in the zone. Portman bay is situated close to the mining region of La Unión. The entire area around the bay was subject to mining from the time of the Roman Empire to 1991. Since 1957, the wastes from mining operations were discharged directly into the sea in the inner part of the bay, while later on, they were also discharged to sea at a distance of the shore. These wastes mainly consisted in ore materials (galena, pyrite and sphalerite), phyllosilicates, in addition to siderite, iron oxides and sometimes alteration products such as jarosite, alunite, kaolinite and greenalite. These materials have suffered a concentration process by floatation with sea water and as a result of the discharge, the whole of the bay has filled up with wastes which also extend into the Mediterranean Sea. The pH and the electrical conductivity (EC) was determined in obtained percolates, together with major ion content, determined by ionic chromatography. The Zn, Pb, Cd and Cu content was determined by electrothermal atomization atomic absorption spectrometry (ETAAS). The As content was measured by atomic fluorescence spectrometry. In addition, the mineralogical composition was determined in the evaporated samples by X-Ray diffraction. A battery of bioassays was applied for the ecotoxicological screening of obtained percolates . Particularly, the toxicity was evaluated by using three assays: microtox bioassay (Vibrio fischeri), embryogenesis assay in sea urchin (Paracentrotus lividus) and survival in estuarine amphipods (Gammarus aequicauda). The obtained results suggest that selected remediation technique reduces significantly the toxicological effect of the percolate to the tested organisms. The ecotoxicological testing may be a useful approach for assessing the toxicity as a complement to chemical analysis. In addition, the use of a battery of bioassays allows diminishing problems related to false positive results. The use of limestone filler constitutes an excellent option in sediments polluted by trace elements, because of risk for human health or ecosystems does not exist after the intervention. in addition, the designed experience allow to optimize stabilizer quantities, and may suppose a big cost-saving project in areas affected by mining activities.
Determination of mercury in hair: Comparison between gold amalgamation-atomic absorption spectrometry and mass spectrometry.

PubMed

Domanico, Francesco; Forte, Giovanni; Majorani, Costanza; Senofonte, Oreste; Petrucci, Francesco; Pezzi, Vincenzo; Alimonti, Alessandro

2017-09-01

Mercury is a heavy metal that causes serious health problems in exposed subjects. The most toxic form, i.e., methylmercury (MeHg), is mostly excreted through human hair. Numerous analytical methods are available for total Hg analysis in human hair, including cold vapour atomic fluorescence spectrometry (CV-AFS), inductively coupled plasma mass spectrometry (ICP-MS) and thermal decomposition amalgamation atomic absorption spectrometry (TDA-AAS). The aim of the study was to compare the TDA-AAS with the ICP-MS in the Hg quantification in human hair. After the washing procedure to minimize the external contamination, from each hair sample two aliquots were taken; the first was used for direct analysis of Hg by TDA-AAS and the second was digested for Hg determination by the ICP-MS. Results indicated that the two data sets were fully comparable (median; TDA-AAS, 475ngg -1 ; ICP-MS, 437ngg -1 ) and were not statistically different (Mann-Whitney test; p=0.44). The two techniques presented results with a good coefficient of correlation (r=0.94) despite different operative ranges and method limits. Both techniques satisfied internal performance requirements and the parameters for method validation resulting sensitive, precise and reliable. Finally, the use of the TDA-AAS can be considered instead of the ICP-MS in hair analysis in order to reduce sample manipulation with minor risk of contamination, less time consuming due to the absence of the digestion step and cheaper analyses. Copyright © 2016 Elsevier GmbH. All rights reserved.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, Chang W.; Iddir, Hakim; Uzun, Alper

To address the challenge of fast, direct atomic-scale visualization of the diffusion of atoms and clusters on surfaces, we used aberration-corrected scanning transmission electron microscopy (STEM) with high scan speeds (as little as ~0.1 s per frame) to visualize the diffusion of (1) a heavy atom (Ir) on the surface of a support consisting of light atoms, MgO(100), and (2) an Ir 3 cluster on MgO(110). Sequential Z-contrast images elucidate the diffusion mechanisms, including the hopping of Ir1 and the rotational migration of Ir 3 as two Ir atoms remain anchored to the surface. Density functional theory (DFT) calculations providedmore » estimates of the diffusion energy barriers and binding energies of the iridium species to the surfaces. The results show how the combination of fast-scan STEM and DFT calculations allow real-time visualization and fundamental understanding of surface diffusion phenomena pertaining to supported catalysts and other materials.« less
REVIEWS OF TOPICAL PROBLEMS: Properties of matter in ultrahigh magnetic fields and the structure of the surface of neutron stars

NASA Astrophysics Data System (ADS)

Liberman, Mikhail A.; Johansson, B.

1995-02-01

The physical properties of atoms, molecules, and solids in ultrahigh magnetic fields B gg 109 G that are believed to exist on the surface of neutron stars are discussed. In these fields, atoms are strongly deformed and elongated along the magnetic field lines; the binding energy and ionizing energy of the atoms are substantially increased and the interatomic interaction is dramatically changed. This strongly modifies the properties of matter at the surface of magnetic neutron stars which are crucial for modelling the pulsar magnetosphere. A scenario for magnetosphere evolution is proposed which suggests free emission for a young pulsar and strong binding of the matter to the surface at a later stage. This later stage is due to strongly bound chains of alternate heavy atoms and light atoms accreted on the surface of the star.
Thermochemical nonequilibrium in atomic hydrogen at elevated temperatures

NASA Technical Reports Server (NTRS)

Scott, R. K.

1972-01-01

A numerical study of the nonequilibrium flow of atomic hydrogen in a cascade arc was performed to obtain insight into the physics of the hydrogen cascade arc. A rigorous mathematical model of the flow problem was formulated, incorporating the important nonequilibrium transport phenomena and atomic processes which occur in atomic hydrogen. Realistic boundary conditions, including consideration of the wall electrostatic sheath phenomenon, were included in the model. The governing equations of the asymptotic region of the cascade arc were obtained by writing conservation of mass and energy equations for the electron subgas, an energy conservation equation for heavy particles and an equation of state. Finite-difference operators for variable grid spacing were applied to the governing equations and the resulting system of strongly coupled, stiff equations were solved numerically by the Newton-Raphson method.
Determination of Cadmium, Lead and Zinc in Vegetables in Jaipur (India).

PubMed

Kumar, Ashok; Verma, P S

2014-01-01

An atomic absorption spectroscopic method was used for the determination of Lead, Cadmium and Zinc in vegetables grown in and around Jaipur food stuffs irrigated with industrial waste water. Vegetable samples were collected after maturity, and analyzed, such as spinach (Spinacia oleracea), ladyfinger (Abelmoschus esulentus), pepper mint (Menthe pipereta), brinjal (Solanum melongena), coriander (Coriandrum sativum), cauliflower (Brassica oleracea), onion (Allium cepa), radish (Raphanus sativus), pointedgourd (Trichosanthes dioica), bottlegourd (Lagenaria siceraria), chilies (Capsicum annum), ribbedgourd (Luffa acutangula) and pumpkin (Curcurbites pepo). The concentration of Lead ranged between 1.40-71.06 ppm, Cadmium 0.61-34.48 ppm and Zinc 0.39-187.26 ppm in vegetable samples. The results reveal that urban consumers are at greater risk of purchasing fresh vegetables with high levels of heavy metal, beyond the permissible limits, as defined by the Indian Prevention of Food Adulteration Act, 1954 and WHO.

Emission spectrographic determination of volatile trace elements in geologic materials by a carrier distillation technique

USGS Publications Warehouse

Barton, H.N.

1986-01-01

Trace levels of chalcophile elements that form volatile sulfide minerals are determined in stream sediments and in the nonmagnetic fraction of a heavy-mineral concentrate of stream sediments by a carrier distillation emission spectrographic method. Photographically recorded spectra of samples are visually compared with those of synthetic standards for the two sample types. Rock and soil samples may also be analyzed by comparison with the stream-sediment standards. A gallium oxide spectrochemical carrier/buffer enhances the early emission of the volatile elements. Detection limits in parts per million attained are: Sb 5, As 20, Bi 0.1, Cd 1, Cu 1, Pb 2, Ag 0.1, Zn 2, and Sn 0.1. A comparison with other methods of analysis, total-burn emission and atomic absorption spectroscopy, shows good correlation for standard reference for materials and samples from a variety of geologic terranes. ?? 1986.
Maize (Zea mays L.) performance in organically amended mine site soils.

PubMed

Oladipo, Oluwatosin Gbemisola; Olayinka, Akinyemi; Awotoye, Olusegun Olufemi

2016-10-01

Organic amendments play an important role in the eco-friendly remediation of degraded mine site soils. This study investigated the quality (essential nutrients and heavy metal content) of maize grown on organically amended soils from three active mines in Nigeria. Soil samples were collected randomly at 0-15 cm depth, air-dried and sieved. Five kg of soil were amended with poultry manure and sawdust (poultry manure only, sawdust only, poultry manure-sawdust mixtures in 3:1, 2:1 and 1:1 ratios) at 10 g kg(-1). Maize (Zea mays L.) seeds were planted and watered for two consecutive periods of 8 weeks, with the control and treatment experiments set up in the screenhouse in quadruples. Harvested tissues were weighed, dried, ground and digested. Chemical properties were determined using standard methods while atomic absorption spectrophotometry was used to determine total metal concentrations (Ca, Mg, Fe, Zn, Pb, Cd and Cu). ANOVA was used to test for significant differences among treatment groups in the various parameters. Application of poultry manure-sawdust mixtures significantly (p < 0.05) enhanced tissue dry matter yield, as well as N, P, K, and Na contents while Zn, Cd, Cu and Pb were immobilized to approximately 50-100%. Treatment with sawdust alone reduced tissue nutrient content resulting in depressed plant yield while poultry manure only though enhanced crop yield, contained higher heavy metal contents. Soil amendments comprised of poultry manure-sawdust mixtures can be effective remediation strategy for mine site soils, as these organic materials help replenish soil nutrients, immobilize heavy metals, and enhance food productivity. Copyright © 2016 Elsevier Ltd. All rights reserved.
X-ray Emission from Highly Charged Heavy Ions Studied at Storage Rings

NASA Astrophysics Data System (ADS)

Ma, X.; Stöhlker, Th.; Bosch, F.; Gumberidze, A.; Kozhuharov, C.; Muthig, A.; Mokler, P. H.; Warczak, A.

2003-01-01

Radiative electron capture at low projectile energies is studied via angular differential cross sections for collisions of bare uranium with low-Z target atoms. Our results show that for high-Z systems relativistic effects such as spin-flip transitions show up in an unambiguous fashion which still persist even in the low-energy domain. Moreover, following REC into the 2p3/2 state a strong alignment of this level was observed by measuring the angular distribution of the Lyα1 transition in H-like uranium. Here, an interference between the leading E1 decay channel and the much weaker M2 multipole transition gives rise to a remarkable modified angular distribution of the emitted photons. For the particular case of hydrogen-like uranium the former variance of the experimental data with theoretical findings is removed when this E1/M2 multipole mixing is taken into account. Finally, with respect to atomic structure studies, a very recent experiment will be discussed aiming on a precise determination of the electron-electron QED contribution to the groundstate ionization potential in He-like uranium.
Studies Concerning the Accumulation of Minerals and Heavy Metals in Fruiting Bodies of Wild Mushrooms

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

Stihi, Claudia; Radulescu, Cristiana; Gheboianu, Anca

2011-10-03

The minerals and heavy metals play an important role in the metabolic processes, during the growth and development of mushrooms, when they are available in appreciable concentration. In this work the concentrations of Cr, Mn, Fe, Ni, Cu, Zn, Se, Cd and Pb were analyzed using the Flame Atomic Absorption spectrometry (FAAS) together with Energy Dispersive X-ray Fluorescence spectrometry (EDXRF) in 3 wild mushrooms species and their growing substrate, collected from various forestry fields in Dambovita County, Romania. The analyzed mushrooms were: Amanita phalloides, Amanita rubescens and Armillariella mellea. The accumulation coefficients were calculated to assess the mobility of mineralsmore » and heavy metals from substrate to mushrooms [1].« less
Crystallization, optimization and preliminary X-ray characterization of a metal-dependent PI-PLC from Streptomyces antibioticus

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

Jackson, Michael R.; Selby, Thomas L.

2012-10-30

A recombinant metal-dependent phosphatidylinositol-specific phospholipase C (PI-PLC) fromStreptomyces antibioticushas been crystallized by the hanging-drop method with and without heavy metals. The native crystals belonged to the orthorhombic space groupP222, with unit-cell parametersa= 41.26,b= 51.86,c = 154.78 Å. The X-ray diffraction results showed significant differences in the crystal quality of samples soaked with heavy atoms. Additionally, drop pinning, which increases the surface area of the drops, was also used to improve crystal growth and quality. The combination of heavy-metal soaks and drop pinning was found to be critical for producing high-quality crystals that diffracted to 1.23 Å resolution.
[Determination of Cu in Shell of Preserved Egg by LIBS Coupled with PLS].

PubMed

Hu, Hui-qin; Xu, Xue-hong; Liu, Mu-hua; Tu, Jian-ping; Huang, Le; Huang, Lin; Yao, Ming-yin; Chen, Tian-bing; Yang, Ping

2015-12-01

In this work, the content of copper in the shell of preserved eggs were determined directly by Laser induced breakdown spectroscopy (LIBS), and the characteristics lines of Cu was obtained. The samples of eggshell were pretreated by acid wet digestion, and the real content of Cu was obtained by atomic absorption spectrophotometer (AAS). Due to the test precision and accuracy of LIBS was influenced by a serious of factors, for example, the complex matrix effect of sample, the enviro nment noise, the system noise of the instrument, the stability of laser energy and so on. And the conventional unvariate linear calibration curve between LIBS intensity and content of element of sample, such as by use of Schiebe G-Lomakin equation, can not meet the requirement of quantitative analysis. In account of that, a kind of multivariate calibration method is needed. In this work, the data of LIBS spectra were processed by partial least squares (PLS), the precision and accuracy of PLS model were compared by different smoothing treatment and five pretreatment methods. The result showed that the correlation coefficient and the accuracy of the PLS model were improved, and the root mean square error and the average relative error were reduced effectively by 11 point smoothing with Multiplicative scatter correction (MSC) pretreatment. The results of the study show that, heavy metal Cu in preserved egg shells can be direct detected accurately by laser induced breakdown spectroscopy, and the next step batch tests will been conducted to find out the relationship of heavy metal Cu content in the preserved egg between the eggshell, egg white and egg yolk. And the goal of the contents of heavy metals in the egg white, egg yolk can be knew through determinate the eggshell by the LIBS can be achieved, to provide new method for rapid non-destructive testing technology for quality and satety of agricultural products.
Gaultheria trichophylla (Royle): a source of minerals and biologically active molecules, its antioxidant and anti-lipoxygenase activities.

PubMed

Alam, Fiaz; Saqib, Qazi Najam Us; Ashraf, Mohammad

2017-01-03

Gaultheria trichophylla (Royle) is used as food and for treating many ailments in folk medicine especially against inflammation. The purpose of this in vitro study was to evaluate the ability of extracts of G. trichophylla as anti-oxidant and anti-inflammatory agent and for its mineral contents. Powdered plant material (100 g) was extracted with 100 ml each of methanol, chloroform, and n-hexane using soxhlet extractor. Antioxidant activity of methanol extract was assessed by DPPH radical scavenging and FRAP assays. Determination of enzyme inhibition activity was determined using 5-LOX inhibitory activity. Total phenolic and flavonoids contents were measured by Folin-Chicalteu and colorimeteric methods respectively. Minerals and heavy metals contents were determined using Atomic absorption spectrophotometer. Qualitative HPLC analysis were performed using some standard phenolic compounds. The highest phenolic (17.5 ± 2.5 mg GA equivalent/g) and flavonoids (41.3 ± 0.1 mg QE equivalent/g) concentrations were found in methanol extract, which also showed more scavenging activity of 1, 1-diphenyl-2-picrylhydrazyl and ferrous reducing power with IC 50 = 81.2 ± 0.2 and IC 50 = 11.2 ± 0.1 μg/ml, respectively. The methanol and chloroform extracts showed best inhibition of 5-lipoxygenase enzyme with 90.5 ± 0.7% and 66.9 ± 0.1% at 0.5 mg/ml, respectively. G. trichophylla extract was also evaluated for mineral contents (K, Na, Ca, Mg, Fe, and Cu), and for chemical profiling of heavy metals (Cr, Pb, Cd, Co, Zn, Ni and Hg). Our current findings suggest that this plant is good source of minerals and concentration of all heavy metals were within permissible limits. The results revealed that this ignored plant has great pharmaceutical and nutraceutical potential.
Effectiveness Study of Drinking Water Treatment Using Clays/Andisol Adsorbent in Lariat Heavy Metal Cadmium (Cd) and Bacterial Pathogens

NASA Astrophysics Data System (ADS)

Pranoto; Inayati; Firmansyah, Fathoni

2018-04-01

Water is a natural resource that is essential for all living creatures. In addition, water also caused of disease affecting humans. The existence of one of heavy metal pollutants cadmium (Cd) in the body of water is an environmental problem having a negative impact on the quality of water resources. Adsorption is one of the ways or methods that are often used for the treatment of wastewater. Clay and allophanic soil were used as Cd adsorbent by batch method. Ceramic filter was used to reduce Cd concentration in the ground water. This study aims to determine the effect of the composition of clay and Allophane, activation temperature and contact time on the adsorption capacity of Cd in the model solution. The optimum adsorption condition and the effectiveness of drinking water treatment in accordance with Regulation of the Minister of Health using clay/Andisol adsorbents in ensnare heavy metals Cd and bacterial pathogens. Identification and characterization of adsorbent is done by using NaF, Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), specific surface area and total acidity specific. The Cd metal concentrations were analysed by atomic absorption spectroscopy. Adsorption isotherms determined by Freundlich and Langmuir equations. Modified water purification technology using ceramic filters are made with a mixture of clay and Andisol composition. The results showed samples of clay and Andisol containing minerals. The optimum condition of adsorption was achieved at 200 °C of activation temperature, 60 minutes of contact time and the 60:40 of clay:Andisol adsorbent composition. Freundlich isotherm represented Cd adsorption on the clay/Andisol adsorbent with a coefficient of determination (R2=0.99) and constant (k=1.59), higher than Langmuir (R2=0.89). The measurement results show the water purification technology using ceramic filters effectively reduce E. coli bacterial and Cd content in the water.
.pi.-conjugated heavy-metal polymers for organic white-light-emitting diodes

DOEpatents

Vardeny, Zeev Valentine; Wojcik, Leonard; Drori, Tomer

2016-09-13

A polymer mixture emits a broad spectrum of visible light that appears white or near-white in the aggregate. The polymer mixture comprises two (or more) components in the active layer. A heavy atom, such as platinum and/or iridium, present in the backbone of the mixture acts via a spin-orbit coupling mechanism to cause the ratio of fluorescent to phosphorescent light emission bands to be of approximately equal strength. These two broad emissions overlap, resulting in an emission spectrum that appears to the eye to be white.
Multipurpose electroslag remelting furnace for modern energy and heavy engineering industry

NASA Astrophysics Data System (ADS)

Dub, A. V.; Dub, V. S.; Kriger, Yu. N.; Levkov, L. Ya.; Shurygin, D. A.; Kissel'man, M. A.; Nekhamin, C. M.; Chernyak, A. I.; Bessonov, A. V.; Kamantsev, S. V.; Sokolov, S. O.

2012-12-01

In 2011, a unique complex based on a multipurpose unit-type electroslag remelting (ESR) furnace is created to meet the demand for large high-quality solid and hollow billets for the products of power, atomic, petrochemical, and heavy machine engineering. This complex has modern low-frequency power supplies with a new control level that ensure a high homogeneity and quality of the billets and an increase in the engineering-and-economical performance of the production. A unique pilot ESR furnace is erected to adjust technological conditions and the main control system elements.
Photoluminescence of epoxy resin modified by carbazole and its halogen derivative at 82 K

NASA Astrophysics Data System (ADS)

Mandowska, E.; Mandowski, A.; Tsvirko, M.

2009-10-01

The spectra and relative quantum yield of fluorescence and phosphorescence were measured for 9-(2,3-epoxypropyl)carbazole (EPK) added to epoxy resin (R) (R 5EPK - 5% weight content of the carbazole group in a polymer) and its mono and dihalogen derivative (Cl and Br). The materials under study have excellent mechanical properties. At 82 K photoluminescence (PL) spectra of these materials are composed of fluorescence (FL) and phosphorescence (PH) components while at 280 K, PH component is not observed. The vibrational frequencies of fluorescence and phosphorescence for R 5EPK were determined using Gaussian deconvolution. A decrease in the fluorescence and an increase in the phosphorescence quantum efficiency were observed after chemical bonding of heavy atoms Cl and Br.
Topological vortex formation in a Bose-Einstein condensate under gravitational field

NASA Astrophysics Data System (ADS)

Kawaguchi, Yuki; Nakahara, Mikio; Ohmi, Tetsuo

2004-10-01

Topological phase imprinting is a unique technique for vortex formation in a Bose-Einstein condensate (BEC) of an alkali-metal gas, in that it does not involve rotation: the BEC is trapped in a quadrupole field with a uniform bias field which is reversed adiabatically leading to vortex formation at the center of the magnetic trap. The scenario has been experimentally verified by Leanhardt employing Na23 atoms. Recently similar experiments have been conducted by Hirotani in which a BEC of Rb87 atoms was used. In the latter experiments the authors found that fine-tuning of the field reverse time Trev is required to achieve stable vortex formation. Otherwise, they often observed vortex fragmentation or a condensate without a vortex. It is shown in this paper that this behavior can be attributed to the heavy mass of the Rb atom. The confining potential, which depends on the eigenvalue mB of the hyperfine spin F along the magnetic field, is now shifted by the gravitational field perpendicular to the vortex line. Then the positions of two weak-field-seeking states with mB=1 and 2 deviate from each other. This effect is more prominent for BECs with a heavy atomic mass, for which the deviation is greater and, moreover, the Thomas-Fermi radius is smaller. We found, by solving the Gross-Pitaevskii equation numerically, that two condensates interact in a very complicated way leading to fragmentation of vortices, unless Trev is properly tuned.
Simulating Chiral Magnetic and Separation Effects with Spin-Orbit Coupled Atomic Gases

PubMed Central

Huang, Xu-Guang

2016-01-01

The chiral magnetic and chiral separation effects—quantum-anomaly-induced electric current and chiral current along an external magnetic field in parity-odd quark-gluon plasma—have received intense studies in the community of heavy-ion collision physics. We show that analogous effects occur in rotating trapped Fermi gases with Weyl-Zeeman spin-orbit coupling where the rotation plays the role of an external magnetic field. These effects can induce a mass quadrupole in the atomic cloud along the rotation axis which may be tested in future experiments. Our results suggest that the spin-orbit coupled atomic gases are potential simulators of the chiral magnetic and separation effects. PMID:26868084
Heavy metal concentrations in soils as determined by laser-induced breakdown spectroscopy (LIBS), with special emphasis on chromium.

PubMed

Senesi, G S; Dell'Aglio, M; Gaudiuso, R; De Giacomo, A; Zaccone, C; De Pascale, O; Miano, T M; Capitelli, M

2009-05-01

Soil is unanimously considered as one of the most important sink of heavy metals released by human activities. Heavy metal analysis of natural and polluted soils is generally conducted by the use of atomic absorption spectroscopy (AAS) or inductively coupled plasma optical emission spectroscopy (ICP-OES) on adequately obtained soil extracts. Although in recent years the emergent technique of laser-induced breakdown spectroscopy (LIBS) has been applied widely and with increasing success for the qualitative and quantitative analyses of a number of heavy metals in soil matrices with relevant simplification of the conventional methodologies, the technique still requires further confirmation before it can be applied fully successfully in soil analyses. The main objective of this work was to demonstrate that new developments in LIBS technique are able to provide reliable qualitative and quantitative analytical evaluation of several heavy metals in soils, with special focus on the element chromium (Cr), and with reference to the concentrations measured by conventional ICP spectroscopy. The preliminary qualitative LIBS analysis of five soil samples and one sewage sludge sample has allowed the detection of a number of elements including Al, Ca, Cr, Cu, Fe, Mg, Mn, Pb, Si, Ti, V and Zn. Of these, a quantitative analysis was also possible for the elements Cr, Cu, Pb, V and Zn based on the obtained linearity of the calibration curves constructed for each heavy metal, i.e., the proportionality between the intensity of the LIBS emission peaks and the concentration of each heavy metal in the sample measured by ICP. In particular, a triplet of emission lines for Cr could be used for its quantitative measurement. The consistency of experiments made on various samples was supported by the same characteristics of the laser-induced plasma (LIP), i.e., the typical linear distribution confirming the existence of local thermodynamic equilibrium (LTE) condition, and similar excitation temperatures and comparable electron number density measured for all samples. An index of the anthropogenic contribution of Cr in polluted soils was calculated in comparison to a non-polluted reference soil. Thus, the intensity ratios of the emission lines of heavy metal can be used to detect in few minutes the polluted areas for which a more detailed sampling and analysis can be useful.
MCCE2: improving protein pKa calculations with extensive side chain rotamer sampling.

PubMed

Song, Yifan; Mao, Junjun; Gunner, M R

2009-11-15

Multiconformation continuum electrostatics (MCCE) explores different conformational degrees of freedom in Monte Carlo calculations of protein residue and ligand pK(a)s. Explicit changes in side chain conformations throughout a titration create a position dependent, heterogeneous dielectric response giving a more accurate picture of coupled ionization and position changes. The MCCE2 methods for choosing a group of input heavy atom and proton positions are described. The pK(a)s calculated with different isosteric conformers, heavy atom rotamers and proton positions, with different degrees of optimization are tested against a curated group of 305 experimental pK(a)s in 33 proteins. QUICK calculations, with rotation around Asn and Gln termini, sampling His tautomers and torsion minimum hydroxyls yield an RMSD of 1.34 with 84% of the errors being <1.5 pH units. FULL calculations adding heavy atom rotamers and side chain optimization yield an RMSD of 0.90 with 90% of the errors <1.5 pH unit. Good results are also found for pK(a)s in the membrane protein bacteriorhodopsin. The inclusion of extra side chain positions distorts the dielectric boundary and also biases the calculated pK(a)s by creating more neutral than ionized conformers. Methods for correcting these errors are introduced. Calculations are compared with multiple X-ray and NMR derived structures in 36 soluble proteins. Calculations with X-ray structures give significantly better pK(a)s. Results with the default protein dielectric constant of 4 are as good as those using a value of 8. The MCCE2 program can be downloaded from http://www.sci.ccny.cuny.edu/~mcce. 2009 Wiley Periodicals, Inc.
Comparative assessment of essential and heavy metals in fruits from different geographical origins.

PubMed

Grembecka, Małgorzata; Szefer, Piotr

2013-11-01

The aim of this investigation was to estimate and compare essential and heavy metals contents in 98 commercially available fresh fruits from different geographic regions using multivariate techniques. The concentrations of 12 elements (calcium, magnesium, potassium, sodium, phophorus, cobalt (Co), manganese, iron, chromium (Cr), nickel (Ni), zinc and copper) were determined using flame atomic absorption spectrometry with deuterium-background correction. Phosphorus was determined in the form of phosphomolybdate by a spectrophotometric method. Reliability of the procedure was checked by analysis of the certified reference materials tea (NCS DC 73351), cabbage (IAEA-359) and spinach leaves (NIST-1570). Recoveries of the elements analysed varied between 85.5 and 103%, and precisions for the reference materials were 0.13-6.08%. Based on recommended dietary allowance and adequate intake estimated for essential elements, it was concluded that accessory fruits such as pineapples, raspberries and strawberries supply organism with the highest amounts of bioelements. Although accessory fruits were also found to be the greatest source of Ni among all the analysed fruits, in all the fruits Ni was more abundant than Cr and Co. Significant correlation coefficients (p < 0.001, p < 0.01 and p < 0.05) were found between concentrations of some metals in fresh fruits. Application of ANOVA Kruskal-Wallis test and multivariate techniques such as factor analysis and cluster analysis enabled us to differentiate particular botanical families and types of fruits.
Heavy metals and metalloid content in vegetables and soil collected from the gardens of Zagreb, Croatia.

PubMed

Puntarić, Dinko; Vidosavljević, Domagoj; Gvozdić, Vlatka; Puntarić, Eda; Puntarić, Ida; Mayer, Dijana; Bosnir, Jasna; Lasić, Dario; Jergović, Matijana; Klarić, Ivana; Vidosavljević, Marina; Krivdić, Ivancica

2013-09-01

Aim of this study was to determine concentration of Pb, Cd, As and Hg in green leafy vegetables and soil in the urban area of Zagreb, Croatia and to determine if there is a connection between the contamination of soil and vegetables. Green leafy vegetables and soil samples were taken from the gardens located in the outskirts of the city. Concentrations of Pb, Cd, As and Hg were determined by atomic absorption spectrometry; showing that average concentrations of metals and metalloids in vegetables and in soil, regardless of the location of sampling were below the maximum allowed concentration (MAC). The analysis determined that metal concentrations in only nine vegetable samples (9%) were above maximum allowed values prescribed by national and European legislation (three with higher concentrations of Pb, one with a higher concentration of Cd and five with higher concentrations of Hg). Concentrations of contaminants present in the analysed samples, in general, are lower than the ones published in similar studies. The final distribution and concentration of contaminants in vegetables of Zagreb, besides industry and traffic, is affected by the dominant wind direction.
Efficient Nonlinear Atomization Model for Thin 3D Free Liquid Films

NASA Astrophysics Data System (ADS)

Mehring, Carsten

2007-03-01

Reviewed is a nonlinear reduced-dimension thin-film model developed by the author and aimed at the prediction of spray formation from thin films such as those found in gas-turbine engines (e.g., prefilming air-blast atomizers), heavy-fuel-oil burners (e.g., rotary-cup atomizers) and in the paint industry (e.g., flat-fan atomizers). Various implementations of the model focusing on different model-aspects, i.e., effect of film geometry, surface tension, liquid viscosity, coupling with surrounding gas-phase flow, influence of long-range intermolecular forces during film rupture are reviewed together with a validation of the nonlinear wave propagation characteristics predicted by the model for inviscid planar films using a two-dimensional vortex- method. An extension and generalization of the current nonlinear film model for implementation into a commercial flow- solver is outlined.
Identification of light elements in silicon nitride by aberration-corrected scanning transmission electron microscopy.

PubMed

Idrobo, Juan C; Walkosz, Weronika; Klie, Robert F; Oğüt, Serdar

2012-12-01

In silicon nitride structural ceramics, the overall mechanical and thermal properties are controlled by the atomic and electronic structures at the interface between the ceramic grains and the amorphous intergranular films (IGFs) formed by various sintering additives. In the last ten years the atomic arrangements of heavy elements (rare-earths) at the Si(3)N(4)/IGF interfaces have been resolved. However, the atomic position of light elements, without which it is not possible to obtain a complete description of the interfaces, has been lacking. This review article details the authors' efforts to identify the atomic arrangement of light elements such as nitrogen and oxygen at the Si(3)N(4)/SiO(2) interface and in bulk Si(3)N(4) using aberration-corrected scanning transmission electron microscopy. Published by Elsevier B.V.
Multiple-collision analysis of characteristic X-rays from low-energy Ar 2+ travelling in solid targets

NASA Astrophysics Data System (ADS)

Cipolla, Sam J.; Mildebrath, Mark E.

1983-12-01

The density of atoms in a solid target fosters a multiple-collision mechanism that leads to the production of an equilibrium fraction of L-shell vacancies in an incident heavy ion. It is then possiblein a subsequent ion-atom collision in the solid for an L-vacancy to be transferred to the K-shell of a target atom via rotational coupling of the 2p π-2p σ molecular orbitals formed in the ion-atom quasimolecule. The vacancy-transfer cross section and the equilibrium fraction and lifetime of the vacancies can be found by using an appropriate multiple-collision analysis of the characteristic target and projectile X-rays. Results will be presented for 160-380 keV Ar 2+ incident of targets of Mg, Al, and Si.

Hierarchical Time-Lagged Independent Component Analysis: Computing Slow Modes and Reaction Coordinates for Large Molecular Systems.

PubMed

Pérez-Hernández, Guillermo; Noé, Frank

2016-12-13

Analysis of molecular dynamics, for example using Markov models, often requires the identification of order parameters that are good indicators of the rare events, i.e. good reaction coordinates. Recently, it has been shown that the time-lagged independent component analysis (TICA) finds the linear combinations of input coordinates that optimally represent the slow kinetic modes and may serve in order to define reaction coordinates between the metastable states of the molecular system. A limitation of the method is that both computing time and memory requirements scale with the square of the number of input features. For large protein systems, this exacerbates the use of extensive feature sets such as the distances between all pairs of residues or even heavy atoms. Here we derive a hierarchical TICA (hTICA) method that approximates the full TICA solution by a hierarchical, divide-and-conquer calculation. By using hTICA on distances between heavy atoms we identify previously unknown relaxation processes in the bovine pancreatic trypsin inhibitor.
Automated structure solution, density modification and model building.

PubMed

Terwilliger, Thomas C

2002-11-01

The approaches that form the basis of automated structure solution in SOLVE and RESOLVE are described. The use of a scoring scheme to convert decision making in macromolecular structure solution to an optimization problem has proven very useful and in many cases a single clear heavy-atom solution can be obtained and used for phasing. Statistical density modification is well suited to an automated approach to structure solution because the method is relatively insensitive to choices of numbers of cycles and solvent content. The detection of non-crystallographic symmetry (NCS) in heavy-atom sites and checking of potential NCS operations against the electron-density map has proven to be a reliable method for identification of NCS in most cases. Automated model building beginning with an FFT-based search for helices and sheets has been successful in automated model building for maps with resolutions as low as 3 A. The entire process can be carried out in a fully automatic fashion in many cases.
A general strategy to solve the phase problem in RNA crystallography

PubMed Central

Keel, Amanda Y.; Rambo, Robert P.; Batey, Robert T.; Kieft, Jeffrey S.

2007-01-01

SUMMARY X-ray crystallography of biologically important RNA molecules has been hampered by technical challenges, including finding a heavy-atom derivative to obtain high-quality experimental phase information. Existing techniques have drawbacks, severely limiting the rate at which important new structures are solved. To address this need, we have developed a reliable means to localize heavy atoms specifically to virtually any RNA. By solving the crystal structures of thirteen variants of the G·U wobble pair cation binding motif we have identified an optimal version that when inserted into an RNA helix introduces a high-occupancy cation binding site suitable for phasing. This “directed soaking” strategy can be integrated fully into existing RNA and crystallography methods, potentially increasing the rate at which important structures are solved and facilitating routine solving of structures using Cu-Kα radiation. The success of this method has been proven in that it has already been used to solve several novel crystal structures. PMID:17637337
Electronic and atomic kinetics in solids irradiated with free-electron lasers or swift-heavy ions

NASA Astrophysics Data System (ADS)

Medvedev, N.; Volkov, A. E.; Ziaja, B.

2015-12-01

In this brief review we discuss the transient processes in solids under irradiation with femtosecond X-ray free-electron-laser (FEL) pulses and swift-heavy ions (SHI). Both kinds of irradiation produce highly excited electrons in a target on extremely short timescales. Transfer of the excess electronic energy into the lattice may lead to observable target modifications such as phase transitions and damage formation. Transient kinetics of material excitation and relaxation under FEL or SHI irradiation are comparatively discussed. The same origin for the electronic and atomic relaxation in both cases is demonstrated. Differences in these kinetics introduced by the geometrical effects (μm-size of a laser spot vs nm-size of an ion track) and initial irradiation (photoabsorption vs an ion impact) are analyzed. The basic mechanisms of electron transport and electron-lattice coupling are addressed. Appropriate models and their limitations are presented. Possibilities of thermal and nonthermal melting of materials under FEL and SHI irradiation are discussed.
Physical particularities of nuclear reactors using heavy moderators of neutrons

NASA Astrophysics Data System (ADS)

Kulikov, G. G.; Shmelev, A. N.

2016-12-01

In nuclear reactors, thermal neutron spectra are formed using moderators with small atomic weights. For fast reactors, inserting such moderators in the core may create problems since they efficiently decelerate the neutrons. In order to form an intermediate neutron spectrum, it is preferable to employ neutron moderators with sufficiently large atomic weights, using 233U as a fissile nuclide and 232Th and 231Pa as fertile ones. The aim of the work is to investigate the properties of heavy neutron moderators and to assess their advantages. The analysis employs the JENDL-4.0 nuclear data library and the SCALE program package for simulating the variation of fuel composition caused by irradiation in the reactor. The following main results are obtained. By using heavy moderators with small neutron moderation steps, one is able to (1) increase the rate of resonance capture, so that the amount of fertile material in the fuel may be reduced while maintaining the breeding factor of the core; (2) use the vacant space for improving the fuel-element properties by adding inert, strong, and thermally conductive materials and by implementing dispersive fuel elements in which the fissile material is self-replenished and neutron multiplication remains stable during the process of fuel burnup; and (3) employ mixtures of different fertile materials with resonance capture cross sections in order to increase the resonance-lattice density and the probability of resonance neutron capture leading to formation of fissile material. The general conclusion is that, by forming an intermediate neutron spectrum with heavy neutron moderators, one can use the fuel more efficiently and improve nuclear safety.
High level leaching of heavy metals from colorful ceramic foodwares: a potential risk to human.

PubMed

Aderemi, Taiwo Adedoyin; Adenuga, Adeniyi Abiodun; Oyekunle, John Adekunle Oyedele; Ogunfowokan, Aderemi Okunola

2017-07-01

Ceramic foodwares are among the products used by people on daily basis without being cautious of exposures to heavy metals through possible leaching from the glaze ceramics. This study investigated the levels of heavy metals found in some commonly used ceramic foodwares in Nigeria with the aim of determining levels of human exposures through the use of the ceramics. To achieve this, acid digestion was carried out for the total metal concentrations and leaching tests were done using 4% acetic acid as a leaching agent. Metal concentrations were quantified using flame atomic absorption spectrometry (FAAS) and particle-induced X-ray emission spectrometry (PIXES) analysis. All the ceramic foodwares studied were found to contain varied amounts of heavy metals in their glazes, with concentrations in the range of 26.45-2071.46, 5.20-547.00, 1.24-2681.02, 2590.00-8848.40, 6.42-654.66, 112.69-649.95, 63.38-2518.51, and 3786.51-8249.44 μg g -1 for Pb, Cd, Zn, As, Cu, Cr, Mn, and Fe, respectively. Concentrations of the metals leached from the ceramics were in the range of 0.11-0.97, 0.01-0.28, 0.00-4.19, 1.93-15.00, 0.01-0.41, 0.09-0.60, 0.01-2.14, and 0.01-11.53 mgL -1 for Pb, Cd, Zn, As, Cu, Cr, Mn, and Fe, respectively. Comparing the ratio of the metals leached from the ceramic wares with those of the metal oxides in the ceramics, it was noticeable that not all the metals detected in the ceramic samples were domiciled in the glaze but in the clay materials used for the ceramics.
Quality assessment and public health status of harvested rainwater in a peri-urban community in Edo State of Nigeria.

PubMed

Igbinosa, Isoken H; Aighewi, Isoken T

2017-08-01

The harvested rainwater is an alternative water source in communities where there is limited or scarcity of water distribution system. However, contamination of roof-harvested rainwater is of immense concern to the general public health. Therefore, this study was initiated to assess the levels of physicochemical quality and heavy metal concentrations in the harvested rainwater from Oluku communities in Benin City, Edo State, Nigeria. The roof-harvested rainwater samples were collected from 20 independent different residential households in Oluku communities, between April 2015 and September 2015. Physicochemical analyses were carried out using standard analytical methods, and heavy metal concentrations were determined using atomic absorption spectrophotometry. The evaluation of the rainwater harvesting shows that 60% (12/20) of the roofs were made of corrugated iron sheets; aluminum sheets, 20% (4/20); asbestos, 10% (2/20); and open space was 10% (2/20). Also, the storage systems used for the storage of harvested rainwater were as follows: PVC tanks, 20% (4/20); drums, 30% (6/20); buckets, 25% (5/20); and wells, 25% (5/20). The physicochemical indicators investigated (temperature, nitrate, chlorine content, electrical conductivity, phosphate, total dissolved solids, and sulfate) were within World Health Organization (WHO) guidelines. However, some pH levels of the roof-harvested rainwater were acidic and below the WHO standard. Furthermore, a high value of turbidity was observed in some locations and exceeded the WHO guidelines. Though some heavy metal indicators (Zn, Na, K, and Ca) in this study were within the WHO guidelines, some locations revealed heavy metal (Cu, Fe, and Cd) concentrations slightly above the WHO guidelines. There is need for proper rainwater harvesting system and continuous monitoring of harvested rainwater for potable uses.
Dietary intake of heavy metals from eight highly consumed species of cultured fish and possible human health risk implications in Bangladesh.

PubMed

Ullah, A K M Atique; Maksud, M A; Khan, S R; Lutfa, L N; Quraishi, Shamshad B

2017-01-01

Concentrations of five heavy metals (Pb, Cd, Cr, As and Hg) in eight highly consumed cultured fish species ( Labeo rohita, Clarias gariepinus, Hypophthalmichthys molitrix, Cyprinus capio, Puntius sarana, Oreochromis mossambicus, Pangasius pangasius and Anabas testudineus ) collected from four wholesale markets of Dhaka city, Bangladesh (Karwan Bazar, Mohammadpur Town Hall, Newmarket and Mirpur-1) were measured using atomic absorption spectrometry (AAS) in order to evaluate the potential human health risks from the consumption of fish. The estimated daily intake (EDI) of all the studied heavy metals calculated on the basis of mean fish consumption of 49.5 g person -1 d -1 by Bangladeshi households indicated that no risk to people's health with respect to the EDI of investigated heavy metals through the consumption of the fish samples. From the human health point of view, the estimation of non-carcinogenic risk indicated that intake of individual heavy metal through the consumption of fish was safe for human health, whereas, consumption of combined heavy metals suggested potential health risk to highly exposed consumers. However, the estimation of carcinogenic risk of arsenic due to the consumption of fish indicated that consumers remain at risk of cancer.
Common plants as alternative analytical tools to monitor heavy metals in soil

PubMed Central

2012-01-01

Background Herbaceous plants are common vegetal species generally exposed, for a limited period of time, to bioavailable environmental pollutants. Heavy metals contamination is the most common form of environmental pollution. Herbaceous plants have never been used as natural bioindicators of environmental pollution, in particular to monitor the amount of heavy metals in soil. In this study, we aimed at assessing the usefulness of using three herbaceous plants (Plantago major L., Taraxacum officinale L. and Urtica dioica L.) and one leguminous (Trifolium pratense L.) as alternative indicators to evaluate soil pollution by heavy metals. Results We employed Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) to assess the concentration of selected heavy metals (Cu, Zn, Mn, Pb, Cr and Pd) in soil and plants and we employed statistical analyses to describe the linear correlation between the accumulation of some heavy metals and selected vegetal species. We found that the leaves of Taraxacum officinale L. and Trifolium pratense L. can accumulate Cu in a linearly dependent manner with Urtica dioica L. representing the vegetal species accumulating the highest fraction of Pb. Conclusions In this study we demonstrated that common plants can be used as an alternative analytical tool for monitoring selected heavy metals in soil. PMID:22594441
Assessment of heavy metals in Averrhoa bilimbi and A. carambola fruit samples at two developmental stages.

PubMed

Soumya, S L; Nair, Bindu R

2016-05-01

Though the fruits of Averrhoa bilimbi and A. carambola are economically and medicinally important, they remain underutilized. The present study reports heavy metal quantitation in the fruit samples of A. bilimbi and A. carambola (Oxalidaceae), collected at two stages of maturity. Heavy metals are known to interfere with the functioning of vital cellular components. Although toxic, some elements are considered essential for human health, in trace quantities. Heavy metals such as Cr, Mn, Co, Cu, Zn, As, Se, Pb, and Cd were analyzed by atomic absorption spectroscopy (AAS). The samples under investigation included, A. bilimbi unripe (BU) and ripe (BR), A. carambola sour unripe (CSU) and ripe (CSR), and A. carambola sweet unripe (CTU) and ripe (CTR). Heavy metal analysis showed that relatively higher level of heavy metals was present in BR samples compared to the rest of the samples. The highest amount of As and Se were recorded in BU samples while Mn content was highest in CSU samples and Co in CSR. Least amounts of Cr, Zn, Se, Cd, and Pb were noted in CTU while, Mn, Cu, and As were least in CTR. Thus, the sweet types of A. carambola (CTU, CTR) had comparatively lower heavy metal content. There appears to be no reason for concern since different fruit samples of Averrhoa studied presently showed the presence of various heavy metals in trace quantities.
Synthesis efficiency of heavy carbon clusters from ETFE ablated by different numbers of laser pulse in vacuum

NASA Astrophysics Data System (ADS)

Shibagaki, K.; Takada, N.; Sasaki, K.; Kadota, K.

2002-09-01

We have carried out mass spectral analysis of positive ions produced by laser ablation of a copolymer of ethylene and tetrafluoroethylene (ETFE: [CH 2CH 2CF 2CF 2] n) in vacuum using time-of-flight mass spectrometry (TOF-MS). The surfaces of the ETFE targets irradiated by different numbers of laser pulse were analyzed by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Heavy carbon cluster ions C n+ with n≥30 were observed in the mass spectra. The fractional abundance of heavy clusters in the mass spectrum decreased with the number of laser pulse. On the other hand, carbon became rich in the atomic composition of the laser-irradiated surface, and the eroded area on the surface increased with the number of laser pulse. From these results, it is suggested that the carbon-rich material surface results in the less efficient production of heavy carbon clusters. In addition, it is also suggested that clustering reactions in eroded craters do not contribute to the synthesis of heavy clusters.
Evidence for strong Breit interaction in dielectronic recombination of highly charged heavy ions.

PubMed

Nakamura, Nobuyuki; Kavanagh, Anthony P; Watanabe, Hirofumi; Sakaue, Hiroyuki A; Li, Yueming; Kato, Daiji; Currell, Fred J; Ohtani, Shunsuke

2008-02-22

Resonant strengths have been measured for dielectronic recombination of Li-like iodine, holmium, and bismuth using an electron beam ion trap. By observing the atomic number dependence of the state-resolved resonant strength, clear experimental evidence has been obtained that the importance of the generalized Breit interaction (GBI) effect on dielectronic recombination increases as the atomic number increases. In particular, it has been shown that the GBI effect is exceptionally strong for the recombination through the resonant state [1s2s(2)2p(1/2)](1).
Creating entanglement using integrals of motion

NASA Astrophysics Data System (ADS)

Olshanii, Maxim; Scoquart, Thibault; Yampolsky, Dmitry; Dunjko, Vanja; Jackson, Steven Glenn

2018-01-01

A quantum Galilean cannon is a one-dimensional sequence of N hard-core particles with special mass ratios and a hard wall; conservation laws due to the reflection group AN prevent both classical stochastization and quantum diffraction. It is realizable through specie-alternating mutually repulsive bosonic soliton trains. We show that an initial disentangled state can evolve into one where the heavy and light particles are entangled, and we propose a sensor, containing Ntotal atoms, with a √{Ntotal} times higher sensitivity than in a one-atom sensor with Ntotal repetitions.
3D simulation of LISM oxygen flux with PUIs inside of heliosphere

DOE PAGES

Kawamura, Akito D.; Heerikhuisen, Jacob; Pogorelov, Nikolai V.; ...

2012-11-20

The structure of the heliospheric interface has attracted increasing attention with continual improvements in modelling and observations, during the last half decade. The Interstellar Boundary Explore (IBEX) spacecraft is returning important data that require a theoretical model of Heliosphere to ensure proper interpretation. Furthermore, we develop a framework for understanding the measurements of heavier-than-hydrogen atoms by IBEX in terms of a 3D MHD-neutral numerical solution of the sun's interaction with the interstellar medium, combined with a test particle approach for heavy atoms and ions.
Tuning the electronic structure of graphene through alkali metal and halogen atom intercalation

NASA Astrophysics Data System (ADS)

Ahmad, Sohail; Miró, Pere; Audiffred, Martha; Heine, Thomas

2018-04-01

The deposition, intercalation and co-intercalation of heavy alkali metals and light halogens atoms in graphene mono- and bilayers have been studied using first principles density-functional calculations. Both the deposition and the intercalation of alkali metals gives rise to n-type doping due to the formation of M+-C- pairs. The co-intercalation of a 1:1 ratio of alkali metals and halogens derives into the formation of ionic pairs among the intercalated species, unaltering the electronic structure of the layered material.
Atomic Fine-Structure Diagnostic and Cooling Transitions for Far Infrared and Submillimeter Observations

NASA Astrophysics Data System (ADS)

Balance, Connor

Some of the strongest emission lines observed from a variety of astronomical sources originate from transitions between fine-structure levels in the ground term of neutral atoms and lowly-charged ions. These fine-structure levels are populated due to collisions with -, H+, H, He, and/or H2 depending on the temperature and ionization fraction of e the environment. As fine-structure excitation measurements are rare, modeling applications depend on theoretically determined rate coefficients. However, for many ions electron collision studies have not been performed for a decade or more, while over that time period the theoretical/computational methodology has significantly advanced. For heavy-particle collisions, very few systems have been studied. As a result, most models rely on estimates or on low-quality collisional data for fine-structure excitation. To significantly advance the state of fine-structure data for astrophysical models, we propose a collaborative effort in electron collisions, heavy-particle collisions, and quantum chemistry. Using the R-matrix method, fine-structure excitation due to electron collisions will be investigated for C, O, Ne^+, Ne^2+, Ar^+, Ar^2+, Fe, Fe^+, and Fe^2+. Fine-structure excitation due to heavy-particle collisions will be studied with a fully quantum molecular-orbital approach using potential energy surfaces computed with a multireference configuration-interaction method. The systems to be studied include: C/H^+, C/H2, O/H^+, O/H2, Ne^+/H, Ne^+/H2, Ne^2+/H, Ne^2+/H2, Fe/H^+, Fe^+/H, and Fe^2+/H. 2D rigid-rotor surfaces will be constructed for H2 collisions, internuclear distance dependent spin-orbit coupling will be computed in some cases, and all rate coefficients will be obtained for the temperature range 10-2000 K. The availability the proposed fine-structure excitation data will lead to deeper examination and understanding of the properties of many astrophysical environments, including young stellar objects, protoplanetary disks, planetary nebulae, photodissociation regions, active galactic nuclei, and x-ray dominated regions, hence elevating the scientific return from current (SOFIA, Spitzer, Herschel, HST) and upcoming (JWST) NASA IR/Submm astrophysics missions, as well as from ground-based telescopes.
Photochemical properties of squarylium cyanine dyes.

PubMed

Ferreira, D P; Conceição, D S; Ferreira, V R A; Graça, V C; Santos, P F; Vieira Ferreira, L F

2013-11-01

This study presents several new squarylium dyes derived from benzothiazole and benzoselenazole with several structural variations, namely the nature of the heteroaromatic ring and the length of the N,N'-dialkyl groups. Before being investigated in connection with their effect on living cells and/or tissues, these novel compounds were characterized, namely with respect to the determination of their main photophysical parameters. Therefore, a study of the ground state absorption, fluorescence emission (quantum yields and lifetimes) and singlet oxygen generation quantum yields was performed for all the compounds synthesized in order to evaluate their efficiency as photosensitizers. An increase of the alkyl chain length from ethyl to hexyl did not produce a clear change in the fluorescence quantum yields, showing no influence on the photoisomerization process. Heavy atom inclusion (Se instead of S) enhanced the singlet oxygen generation efficiency and decreased the intensity of the fluorescence emission. The external heavy atom effect (I(-) as a counterion instead of CF3SO3(-)) produced a significant increase in the singlet oxygen formation quantum yield (about 20%). Transient absorption studies in aerated and oxygen free samples revealed that the photoisomerization process, which could compete with the triplet state formation for all dyes in solution, is a negligible pathway for the excited state deactivation, in accordance with the rigidity introduced by the squaric ring into the polymethine chain of the dye, both in chloroform and ethanol. However, in the case of the chloroform solution a new transient was detected in air equilibrated solutions, resulting from a reaction of the excited squarylium dye in the singlet state with CHCl3˙, and assigned to the radical cation (SQ(+)˙) of the dye.
Exposure assessment of heavy metals in an e-waste processing area in northern Vietnam.

PubMed

Oguri, Tomoko; Suzuki, Go; Matsukami, Hidenori; Uchida, Natsuyo; Tue, Nguyen Minh; Tuyen, Le Huu; Viet, Pham Hung; Takahashi, Shin; Tanabe, Shinsuke; Takigami, Hidetaka

2018-04-15

In developing countries, inappropriate recycling of e-waste has resulted in the environmental release of toxicants, including heavy metals, that may have deleterious health effects. In this study, we estimated daily metal intakes in five households in a Vietnamese village located in an e-waste processing area and assessed the health risk posed by exposure to the metals. Garden soil, floor dust, 24-h duplicate diet, and ambient air samples were collected from five households in northern Vietnam in January 2014. All samples were acid-digested, and contents of Cd, Cu, Mn, Pb, Sb, and Zn were measured by using ICP mass spectrometry and ICP atomic emission spectroscopy. In addition, the soil, dust, and diet samples were subjected to an bioaccessibility extraction test to determine bioaccessible metal concentrations. Hazard quotients were estimated from bioaccessible metal concentrations, provisional tolerable weekly intakes, and reference doses. Garden soil and floor dust were estimated to be mainly contributors to daily Pb intake, as indicated by calculations using bioaccessible metal concentrations and the U.S. Environmental Protection Agency soil plus dust ingestion rate. Diet was suggested to contribute significantly to daily Cd, Cu, Mn, Sb, and Zn intake. Estimated metal exposures via inhalation were negligible, as indicated by calculations using International Atomic Energy Agency reference inhalation rates. The maximum hazard quotients were calculated as 0.2 (Cd), 0.09 (Cu), 0.3 (Mn), 0.6 (Pb), 0.2 (Sb), and 0.5 (Zn), on the basis of bioaccessible metal concentrations. The contributions of Cd, Cu, Mn, Sb, and Zn except Pb to potential noncancer risk for adult residents of the five households in the e-waste processing area may be low. Copyright © 2017 Elsevier B.V. All rights reserved.
Determination of heavy metals in the ambient atmosphere.

PubMed

Suvarapu, Lakshmi Narayana; Baek, Sung-Ok

2017-01-01

Heavy metal determination in ambient air is an important task for environmental researchers because of their toxicity to human beings. Some heavy metals (hexavalent chromium (Cr), arsenic (As), cadmium (Cd) and nickel (Ni)) have been listed as carcinogens. Furthermore, heavy metals in the atmosphere can accumulate in various plants and animals and enter humans through the food chain. This article reviews the determination of heavy metals in the atmosphere in different areas of the world since 2006. The results showed that most researchers concentrated on toxic metals, such as Cr, Cd, Ni, As and lead. A few studies used plant materials as bio-monitors for the atmospheric levels of heavy metals. Some researchers found higher concentrations of heavy metals surrounding industrial areas compared with residential and/or commercial areas. Most studies reported the major sources of the particulate matter and heavy metals in the atmosphere to be industrial emissions, vehicular emissions and secondary aerosols.
Meteoric Ions in Planetary Ionospheres

NASA Technical Reports Server (NTRS)

Pesnell, W. D.; Grebowsky, Joseph M.; Vondrak, Richard R. (Technical Monitor)

2001-01-01

Solar system debris, in the form of meteoroids, impacts every planet. The flux, relative composition and speed of the debris at each planet depends on the planet's size and location in the solar system. Ablation in the atmosphere evaporates the meteoric material and leaves behind metal atoms. During the ablation process metallic ions are formed by impact ionization. For small inner solar system planets, including Earth, this source of ionization is typically small compared to either photoionization or charge exchange with ambient molecular ions. For Earth, the atmosphere above the main deposition region absorbs the spectral lines capable of ionizing the major metallic atoms (Fe and Mg) so that charge exchange with ambient ions is the dominant source. Within the carbon dioxide atmosphere of Mars (and possibly Venus), photoionization is important in determining the ion density. For a heavy planet like Jupiter, far from the sun, impact ionization of ablated neutral atoms by impacts with molecules becomes a prominent source of ionization due to the gravitational acceleration to high incident speeds. We will describe the processes and location and extent of metal ion layers for Mars, Earth and Jupiter, concentrating on flagging the uncertainties in the models at the present time. This is an important problem, because low altitude ionosphere layers for the planets, particularly at night, probably consist predominantly of metallic ions. Comparisons with Earth will be used to illustrate the differing processes in the three planetary atmospheres.

40 CFR 86.1112-87 - Determining the compliance level and reporting of test results.

Code of Federal Regulations, 2010 CFR

2010-07-01

... ENGINES (CONTINUED) Nonconformance Penalties for Gasoline-Fueled and Diesel Heavy-Duty Engines and Heavy...) The final deteriorated test results for each heavy-duty engine or light-duty truck tested according to... information the Administrator may request relevant to the determination as to whether the new heavy-duty...
Synthesis of cobalt nanoparticles on Si (100) by swift heavy ion irradiation

PubMed Central

2013-01-01

We report the growth and characterization of uniform-sized nanoparticles of cobalt on n-type silicon (100) substrates by swift heavy ion (SHI) irradiation. The Co thin films of 25-nm thicknesses were grown by e-beam evaporation and irradiated with two different types of ions, 45-MeV Li3+ and 100-MeV O7+ ions with fluences ranging from 1 × 1011 to 1 × 1013 ions/cm2. SHI irradiation, with the beam rastered over the area of the film, resulted in the restructuring of the film into a dense array of Co nanostructures. Surface topography studied by atomic force microscopy revealed narrowed size distributions, with particle sizes ranging from 20 to 50 nm, formed through a self-organized process. Ion fluence-dependent changes in crystallinity of the Co nanostructures were determined by glancing angle X-ray diffraction. Rutherford backscattering spectroscopy analysis showed the absence of beam-induced mixing in this system. Surface restructuring and beam-induced crystallization are the dominant effects, with the nanoparticle size and density being dependent on the ion fluence. Results are analyzed in the context of molecular dynamics calculations of electron-lattice energy transfer. PMID:24138985
Detection of heavy metal Cd in polluted fresh leafy vegetables by laser-induced breakdown spectroscopy.

PubMed

Yao, Mingyin; Yang, Hui; Huang, Lin; Chen, Tianbing; Rao, Gangfu; Liu, Muhua

2017-05-10

In seeking a novel method with the ability of green analysis in monitoring toxic heavy metals residue in fresh leafy vegetables, laser-induced breakdown spectroscopy (LIBS) was applied to prove its capability in performing this work. The spectra of fresh vegetable samples polluted in the lab were collected by optimized LIBS experimental setup, and the reference concentrations of cadmium (Cd) from samples were obtained by conventional atomic absorption spectroscopy after wet digestion. The direct calibration employing intensity of single Cd line and Cd concentration exposed the weakness of this calibration method. Furthermore, the accuracy of linear calibration can be improved a little by triple Cd lines as characteristic variables, especially after the spectra were pretreated. However, it is not enough in predicting Cd in samples. Therefore, partial least-squares regression (PLSR) was utilized to enhance the robustness of quantitative analysis. The results of the PLSR model showed that the prediction accuracy of the Cd target can meet the requirement of determination in food safety. This investigation presented that LIBS is a promising and emerging method in analyzing toxic compositions in agricultural products, especially combined with suitable chemometrics.
Faster extraction of heavy metals from soils using vacuum and ultrasonic energy.

PubMed

Pontes, Fernanda V M; Carneiro, Manuel C; de da Souza, Evelyn M F; da Silva, Lílian I D; Monteiro, Maria Inês C; Neto, Arnaldo A

2013-01-01

A fast vacuum- and ultrasound-assisted acid extraction of Co, Cu, Fe, Mn, Pb, and Zn from soils using a homemade system has been investigated. Preliminarily, a full factorial design with two levels and three variables (extracting agent, extraction temperature, and sonication time) was applied to optimize the extraction conditions (without vacuum) for some heavy metals (Cu, Mn, Pb, and Zn). The best results were obtained with a 3:1 HCI extraction solution, temperature of 80 degrees C, and time of 2 h. As this sonication time was too long, a vacuum pump was used to produce air bubbles in order to increase the contact between the sample and the extracting agent and to prevent the sample sedimentation. This improvement drastically reduced the sonication time to 2 min. Under these conditions, Co, Cu, Mn, and Zn were totally extracted (recoveries of 86-99%), while recoveries of 73-76 and 74% were obtained for Fe and Pb, respectively. The LOD values using flame atomic absorption spectrometry for determination of Co, Cu, Fe, Mn, Pb, and Zn were 3.2, 7.5, 37.5, 7.5, 22.5, and 3.8 micro glg, respectively. The RSDs were lower than 11% (n = 3).
Synthesis of cobalt nanoparticles on Si (100) by swift heavy ion irradiation.

PubMed

Attri, Asha; Kumar, Ajit; Verma, Shammi; Ojha, Sunil; Asokan, Kandasami; Nair, Lekha

2013-10-18

We report the growth and characterization of uniform-sized nanoparticles of cobalt on n-type silicon (100) substrates by swift heavy ion (SHI) irradiation. The Co thin films of 25-nm thicknesses were grown by e-beam evaporation and irradiated with two different types of ions, 45-MeV Li3+ and 100-MeV O7+ ions with fluences ranging from 1 × 1011 to 1 × 1013 ions/cm2. SHI irradiation, with the beam rastered over the area of the film, resulted in the restructuring of the film into a dense array of Co nanostructures. Surface topography studied by atomic force microscopy revealed narrowed size distributions, with particle sizes ranging from 20 to 50 nm, formed through a self-organized process. Ion fluence-dependent changes in crystallinity of the Co nanostructures were determined by glancing angle X-ray diffraction. Rutherford backscattering spectroscopy analysis showed the absence of beam-induced mixing in this system. Surface restructuring and beam-induced crystallization are the dominant effects, with the nanoparticle size and density being dependent on the ion fluence. Results are analyzed in the context of molecular dynamics calculations of electron-lattice energy transfer.
Synthesis of cobalt nanoparticles on Si (100) by swift heavy ion irradiation

NASA Astrophysics Data System (ADS)

Attri, Asha; Kumar, Ajit; Verma, Shammi; Ojha, Sunil; Asokan, Kandasami; Nair, Lekha

2013-10-01

We report the growth and characterization of uniform-sized nanoparticles of cobalt on n-type silicon (100) substrates by swift heavy ion (SHI) irradiation. The Co thin films of 25-nm thicknesses were grown by e-beam evaporation and irradiated with two different types of ions, 45-MeV Li3+ and 100-MeV O7+ ions with fluences ranging from 1 × 1011 to 1 × 1013 ions/cm2. SHI irradiation, with the beam rastered over the area of the film, resulted in the restructuring of the film into a dense array of Co nanostructures. Surface topography studied by atomic force microscopy revealed narrowed size distributions, with particle sizes ranging from 20 to 50 nm, formed through a self-organized process. Ion fluence-dependent changes in crystallinity of the Co nanostructures were determined by glancing angle X-ray diffraction. Rutherford backscattering spectroscopy analysis showed the absence of beam-induced mixing in this system. Surface restructuring and beam-induced crystallization are the dominant effects, with the nanoparticle size and density being dependent on the ion fluence. Results are analyzed in the context of molecular dynamics calculations of electron-lattice energy transfer.
Heavy metals content in degraded agricultural soils of a mountain region related to soil properties

NASA Astrophysics Data System (ADS)

Navarro-Pedreño, José; Belén Almendro-Candel, María; Gómez, Ignacio; Jordán, Manuel M.; Bech, Jaume; Zorpas, Antonis

2017-04-01

Agriculture has been practiced for long time in Mediterranean regions. Intensive agriculture and irrigation have developed mainly in the valleys and coastal areas. In the mountainous areas, dry farming has been practiced for centuries. Soils have been fertilized using mainly organic amendments. Plants extracted nutrients and other elements like heavy metals presented in soils and agricultural practices modified soil properties that could favor the presence of heavy metals. In this work, it has been checked the content of heavy metals in 100 agricultural soils samples of the NorthWest area of the province of Alicante (Spain) which has been long cultivated with cereals and olive trees, and now soils are abandoned and degraded because of the low agricultural yields. European policy has the aim to improve the sustainable agriculture and recover landscapes of mountain regions. So that, it is important to check the state of the soils (Marques et al. 2007). Soils samples (arable layer) were analyzed determining: pH (1:5, w/v, water extract), equivalent calcium carbonate content, organic matter by Walkley-Black method (Nelson and Sommers 1996), micronutrients (Cu, Fe, Mn, Zn) extracted with DTPA (Lindsay and Norvell, 1978) and measured by atomic absorption spectrometry, and total content of metals (Cd, Cr, Ni, Pb) measured in soil samples after microwave acid digestion (Moral et al. 1996), quantifying the content of metals by ICP analysis. The correlation between soil properties and metals. The results indicated that pH and carbonates are the most important properties of these soils correlated with the metals (both micronutrients and heavy metals). The available micronutrients (all of them) are close correlated with the pH and carbonates in soils. Moreover, heavy metals like Pb and Ni are related to available Mn and Zn. Keywords: pH, carbonates, heavy metals, abandoned soils. References: Lindsay,W.L., andW.A. Norvell. 1978. "Development of a DTPA Soil Test for Zinc, Iron, Manganese and Copper." Soil Science Society of America Journal 42: 421-428. Marques,M.J., R. Jimenez-Ballesta, A. Á lvarez, and R. Bienes. 2007. "Spanish Research on Soil Damage." Science of the Total Environment 378: 1-4. Moral, R., J. Navarro-Pedreño, I. Gómez, and J. Mataix. 1996. "Quantitative Analysis of Organic Residues: Effects of Samples Preparation in the Determination of Metal." Communications in Soil Science and Plant Analysis 27: 753-761. Nelson, D.W., and L.E. Sommers. 1996. "Total Carbon, Organic Carbon, and Organic Matter." In Methods of Soil Analysis. Part 3. Chemical Methods, edited by D.L. Sparks, A.L. Page, P.A. Helmke, R.H. Loeppert, P.N. Soltanpour, M.A. Tabatabai, C.T. Johnston, M.E. Sumner. Madison, WI: American Society of Agronomy.
Preliminary assessment of heavy metals in water, sediment and macrophyte ( Lemna minor) collected from Anchar Lake, Kashmir, India

NASA Astrophysics Data System (ADS)

Showqi, Irfana; Lone, Farooq Ahmad; Naikoo, Mehrajuddin

2018-06-01

Water samples, sediments and free floating macrophytic plant, Lemna minor specimens were collected from five designated sites in Anchar lake (Srinagar, J&K, India) to assess its heavy metal (Cu, Cr, Zn, Ni, Cd, Pb) load and changes on seasonal basis. The concentration of heavy metals was determined using atomic absorption spectroscopy. Most of the samples were found within limits of maximum permissible concentrations as recommended by WHO (Guidelines for drinking water quality, pp 491-493, 2006). During all the seasons, highest concentration of all heavy metals (Cu, Cr, Zn, Ni, Cd, Pb) was recorded at highly polluted sites of the lake viz. near agricultural fields (S1), near settlements (S3) and SKIMS (S4). These sites received huge agrochemical run-off from the surrounding agricultural fields, solid and liquid wastes from the nearby catchment areas and effluents from Sher-e-Kashmir Institute of Medical Sciences (SKIMS) compared to control site lake centre (S5). Furthermore, most of the metals in water and sediment were found with highest concentration during autumn (Viz., Cu-1.5 ppm; Zn-0.38 ppm; Ni-1.89 ppm; Pb-0.84 ppm in water and Cu-26.9 ppm; Zn-13.6 ppm; Pb-4.33 ppm in sediment) and summer (Viz., Cr-0.68 ppm in water and Ni-4.8 ppm; Cd-2.6 ppm; Cr-8.01 ppm in sediment) seasons. Also in Lemna minor plant highest concentration was observed during summer season (Cu-29.09 ppm; Zn-19.11 ppm; Ni-5.7 ppm; Cd-1.34 ppm; Cr-9.18 ppm and Pb-9.77 ppm). From these observations, it was found that the sources of heavy metals in Anchar lake were both natural and anthropogenic ones. This study recommended that continuous monitoring of heavy metals (Viz; Cu, Cr, Zn, Ni, Cd and Pb) in water, sediment and other aquatic biota of Anchar lake should be directed to protection of ecological status of the lake and its surrounding area.
The structural analysis of shark IgNAR antibodies reveals evolutionary principles of immunoglobulins.

PubMed

Feige, Matthias J; Gräwert, Melissa A; Marcinowski, Moritz; Hennig, Janosch; Behnke, Julia; Ausländer, David; Herold, Eva M; Peschek, Jirka; Castro, Caitlin D; Flajnik, Martin; Hendershot, Linda M; Sattler, Michael; Groll, Michael; Buchner, Johannes

2014-06-03

Sharks and other cartilaginous fish are the phylogenetically oldest living organisms that rely on antibodies as part of their adaptive immune system. They produce the immunoglobulin new antigen receptor (IgNAR), a homodimeric heavy chain-only antibody, as a major part of their humoral adaptive immune response. Here, we report the atomic resolution structure of the IgNAR constant domains and a structural model of this heavy chain-only antibody. We find that despite low sequence conservation, the basic Ig fold of modern antibodies is already present in the evolutionary ancient shark IgNAR domains, highlighting key structural determinants of the ubiquitous Ig fold. In contrast, structural differences between human and shark antibody domains explain the high stability of several IgNAR domains and allowed us to engineer human antibodies for increased stability and secretion efficiency. We identified two constant domains, C1 and C3, that act as dimerization modules within IgNAR. Together with the individual domain structures and small-angle X-ray scattering, this allowed us to develop a structural model of the complete IgNAR molecule. Its constant region exhibits an elongated shape with flexibility and a characteristic kink in the middle. Despite the lack of a canonical hinge region, the variable domains are spaced appropriately wide for binding to multiple antigens. Thus, the shark IgNAR domains already display the well-known Ig fold, but apart from that, this heavy chain-only antibody employs unique ways for dimerization and positioning of functional modules.
Health Risk Assessment of Heavy Metals in Traditional Cosmetics Sold in Tunisian Local Markets

PubMed Central

Nouioui, Mohamed Anouar; Mahjoubi, Salah; Ghorbel, Asma; Ben Haj Yahia, Marouen; Amira, Dorra; Ghorbel, Hayet; Hedhili, Abderrazek

2016-01-01

This study was undertaken in order to determine heavy metal contents in twelve (n = 12) henna brands and eleven (n = 11) kohl products. An analytical test was performed for Pb, Cd, Cu, and Zn in henna and kohl products using atomic absorption spectrophotometery. The overall mean concentrations of heavy metals in henna varied between 1.2 and 8.9 μg g−1 for Pb; 0.8 and 18.6 μg g−1 for Cd; 0.5 μg g−1 and 3.3 μg g−1 for Cu; and 3.7 μg g−1 and 90.0 μg g−1 for Zn. As for kohl products, Pb concentrations ranged between 51.1 μg g−1 and 4839.5 μg g−1, Cd concentrations ranged between 1.0 μg g−1 and 158.6 μg g−1, Cu concentrations ranged between 2.5 μg g−1 and 162.5 μg g−1, and Zn concentrations ranged between 0.7 μg g−1 and 185.0 μg g−1. The results of our study revealed that Pb, Cd, Cu, and Zn contents in investigated samples were high, making from the prolonged use of such products a potential threat to human health. Therefore, major quality controls are recommended in order to enforce acceptable limits of potential contaminants in cosmetics and good manufacturing practice. PMID:27382641
Usage of the Upgraded Vassilissa Separator for Synthesis of Super-Heavy Elements

NASA Astrophysics Data System (ADS)

Yeremin, A. V.; Malyshev, O. N.; Popeko, A. G.; Sagaidak, R. N.; Chepigin, V. I.; Kabachenko, A. P.; Belozerov, A. V.; Chelnokov, M. L.; Gorshkov, V. A.; Svirikhin, A. I.; Korotkov, S. P.; Rohach, J.; Brida, I.; Berek, G.

2002-12-01

Electrostatic separator VASSILISSA is used for exploring complete fussion nuclear reactions. The magnetic analyzer, based on D37 dipole magnet, was installed after the second triplet of quadrupole lenses of the separator for the mass identification of evaporation residues. Mass identification is an powerful tool for identification of recoil atoms of super-heavy elements. The new detection system consisting of the time-of-fiight system and 32-strips position-sensitive detector array was installed in the focal plane of the separator. The mass resolution of the separator after upgrade was found to be about 2.5 %.
Formation of TiO2 nanorings due to rapid thermal annealing of swift heavy ion irradiated films.

PubMed

Thakurdesai, Madhavi; Sulania, I; Narsale, A M; Kanjilal, D; Bhattacharyya, Varsha

2008-09-01

Amorphous thin films of TiO2 deposited by Pulsed Laser Deposition (PLD) method are irradiated by Swift Heavy Ion (SHI) beam. The irradiated films are subsequently annealed by Rapid Thermal Annealing (RTA) method. Atomic Force Microscopy (AFM) study reveals formation of nano-rings on the surface after RTA processing. Phase change is identified by Glancing Angle X-ray Diffraction (GAXRD) and Raman spectroscopy. Optical characterisation is carried out by UV-VIS absorption spectroscopy. Though no shift of absorption edge is observed after irradiation, RTA processing does show redshift.
Membrane separation of hydrocarbons using cycloparaffinic solvents

DOEpatents

Kulkarni, S.S.; Chang, Y.A.; Gatsis, J.G.; Funk, E.W.

1988-06-14

Heavy crude oils which contain metal contaminants such as nickel, vanadium and iron may be separated from light hydrocarbon oils by passing a solution of the crude oil dissolved in a cycloparaffinic hydrocarbon solvent containing from about 5 to about 8 carbon atoms by passing through a polymeric membrane which is capable of maintaining its integrity in the presence of hydrocarbon compounds. The light hydrocarbon oils which possess relatively low molecular weights will be recovered as the permeate while the heavy oils which possess relatively high molecular weights as well as the metal contaminants will be recovered as the retentate.
Membrane separation of hydrocarbons using cycloparaffinic solvents

DOEpatents

Kulkarni, Sudhir S.; Chang, Y. Alice; Gatsis, John G.; Funk, Edward W.

1988-01-01

Heavy crude oils which contain metal contaminants such as nickel, vanadium and iron may be separated from light hydrocarbon oils by passing a solution of the crude oil dissolved in a cycloparaffinic hydrocarbon solvent containing from about 5 to about 8 carbon atoms by passing through a polymeric membrane which is capable of maintaining its integrity in the presence of hydrocarbon compounds. The light hydrocarbon oils which possess relatively low molecular weights will be recovered as the permeate while the heavy oils which possess relatively high molecular weights as well as the metal contaminants will be recovered as the retentate.
Atomic and molecular hydrogen in the circumstellar envelopes of late-type stars

NASA Technical Reports Server (NTRS)

Glassgold, A. E.; Huggins, P. J.

1983-01-01

The distribution of atomic and molecular hydrogen in the expanding circumstellar envelopes of cool evolved stars is discussed. The main concern is to evaluate the effects of photodestruction of H2 by galactic UV radiation, including shielding of the radiation by H2 itself and by dust in the envelope. One of the most important parameters is the H/H2 ratio which is frozen out in the upper atmosphere of the star. For stars with photospheric temperatures greater than about 2500 K, atmospheric models suggest that the outflowing hydrogen is mainly atomic, whereas cooler stars should be substantially molecular. In the latter case, photodissociation of H2 and heavy molecules contribute to the atomic hydrogen content of the outer envelope. The presented estimates indicate that atomic hydrogen is almost at the limit of detection in the C-rich star IRC + 10216, and may be detectable in warmer stars. Failure to detect it would have important implications for the general understanding of circumstellar envelopes.
Fourier transform microwave spectra and ab initio calculation of N-ethylformamide

NASA Astrophysics Data System (ADS)

Ohba, Keisuke; Usami, Tsuyoshi; Kawashima, Yoshiyuki; Hirota, Eizi

2005-06-01

A peptide molecule: N-ethylformamide HCONHCH 2CH 3 (NEFA) was investigated by Fourier transform microwave spectroscopy in order to determine molecular structure, potential barrier to methyl internal rotation, and nuclear quadrupole coupling constant of the nitrogen atom. All the three ( a, b and c) types of transitions were observed; they were split into hyperfine structure components due to nitrogen nuclear quadrupole coupling. The rotational constants of NEFA were determined to be A=9904.8373(6), B=3521.0995(2) and C=2984.9808(2) MHz, with three standard deviations in parentheses. The inertial defect Δ= Icc- Iaa- Ibb was calculated from the rotational constants to be -25.24492(2) uÅ 2, which indicates the ethyl group to be bent out of the peptide linkage plane. A comparison of the observed rotational constants with those calculated by an ab initio molecular orbital method also led us to conclude that the most stable form of NEFA is trans- sc, a conformer with a nonplanar heavy atom skeleton. No evidence has so far been obtained for the existence of other conformers, as was the case for a related molecule: N-ethylacetamide. We have also observed spectra of five singly substituted isotopomers, three 13C and one for each of 15N and 18O, from which we derived a partial rs structure, in fair agreement with an ab initio result.
Cluster formation in nuclear reactions from mean-field inhomogeneities

NASA Astrophysics Data System (ADS)

Napolitani, Paolo; Colonna, Maria; Mancini-Terracciano, Carlo

2018-05-01

Perturbing fluids of neutrons and protons (nuclear matter) may lead, as the most catastrophic effect, to the rearrangement of the fluid into clusters of nucleons. A similar process may occur in a single atomic nucleus undergoing a violent perturbation, like in heavy-ion collisions tracked in particle accelerators at around 30 to 50 MeV per nucleon: in this conditions, after the initial collision shock, the nucleus expands and then clusterises into several smaller nuclear fragments. Microscopically, when violent perturbation are applied to nuclear matter, a process of clusterisation arises from the combination of several fluctuation modes of large-amplitude where neutrons and protons may oscillate in phase or out of phase. The imposed perturbation leads to conditions of instability, the wavelengths which are the most amplified have sizes comparable to small atomic nuclei. We found that these conditions, explored in heavy-ion collisions, correspond to the splitting of a nucleus into fragments ranging from Oxygen to Neon in a time interval shorter than one zeptosecond (10 ‑ 21s). From the out-of-phase oscillations of neutrons and protons another property arises, the smaller fragments belonging to a more volatile phase get more neutron enriched: in the heavy-ion collision case this process, called distillation, reflects in the isotopic distributions of the fragments. The resulting dynamical description of heavy-ion collisions is an improvement with respect to more usual statistical approaches, based on the equilibrium assumption. It allows in fact to characterise also the very fast early stages of the collision process which are out of equilibrium. Such dynamical description is the core of the Boltzmann-Langevin One Body (BLOB) model, which in its latest development unifies in a common approach the description of fluctuations in nuclear matter, and a predictive description of the disintegration of nuclei into nuclear fragments. After a theoretical introduction, a few practical examples will be illustrated. This paper resumes the extended analysis of fluctuations in nuclear matter of ref. [2] and briefly reviews applications to heavy-ion collisions.
Urinary protein excretion profile: A contribution for subclinical renal damage identification among environmental heavy metals exposure in Southeast Brazil

NASA Astrophysics Data System (ADS)

Garlipp, C. R.; Bottini, P. V.; de Capitan, E. M.; Pinho, M. C.; Panzan, A. D. N.; Sakuma, A. M. A.; Paoliello, M. B.

2003-05-01

In Southeast Brazil. Ribeira Valley region has been a major public health concern due to he environmental heavy metals contamination indexes of vegetation, rocks and aquifers, caused by locai mining in the past. Human contamination low levels of heavy rnetals doesn't cause acute intoxication but ni chronic exposure, renal damage may occur with progressive tubuJointerstitial changes evolvil1g to glomemlar 1esiol1, ln this stndy we invesligated the relationship between thc profile of utillan, excreted proteins (glomerular or lubular origin) of arsenic and mercury and blood lead concentration in chiJdren and adults from highly e) qJosed regions of the Ribeira Valley. The subjects were classieed as GROUP 1 (GI; higher environmental risk n=333) and GROUP 2 (G2; lower risk of contamination. n=104). In order to determine the urinary excretion of total protein, albumin (MA, glomerular marker) and alpha i microglobulin (AIM, tubular marker) and the blood lead concentrations. random wine and blood samples were obtaiiied. Plasmatic lead levels were assessed by atomic absorption spectrometty with graphite fumace. Totai protein concentration (PROT) was assessed on a biochemical analyzer ,progallol red method). MA and AIM were determined by nephelometric method. Croup 1 showcd a higher frequency of altered urinary excretion of PROT (GI=3.4%; G2=1.0%), MA (Gl=9.0%; G2=5.1%) and AIM (Gt=7.5%, G2=3.8%), without significant differences between both groups. Elevated arscnic levels were more prevaient among subjects from Group 1 (2.8.8%) and demonstrated a significant corrolation with abiiormal iirinarv excretion of ilbumin and alpha-l-micrglobulin (p=0.019).Leadaand mercury levels showed no difference among the groups and no correlation will MAa and/or M. Oti-c dala suggests that abnormal itrinary protein excretion is relatively frequent in this population independently of the plasmatic or urinaryl heavy metal levels. The early detection of possible renal damage become necessary for effective measures can be taken to prevent clinical nephropathies.
[Concentration of Hg, Pb, Cd, Cr and As in liver Carcharhinus limbatus (Carcharhiniformes: Carcharhinidae) captured in Veracruz, Mexico].

PubMed

Mendoza-Díaz, Fernando; Serrano, Arturo; Cuervo-López, Liliana; López-Jiménez, Alejandra; Galindo, José A; Basañez-Muñoz, Agustin

2013-06-01

Pollution by heavy metals in marine ecosystems in the Gulf of Mexico is one of the hardest conservation issues to solve. Sharks as top predators are bioindicators of the marine ecosystem health, since they tend to bioaccumulate and biomagnify contaminants; they also represent a food source for local consumption. Thus, the objective of this study was to study the possible presence of heavy metals and a metalloid in livers of Carcharhinus limbatus. For this, a total of 19 shark livers were taken from animals captured nearby Tamihua, Veracruz, Mexico from December 2007 to April 2008. 12 out of the 19 captured sharks were males, one was an adult female, three were juvenile males, and three juvenile females. Four heavy metals (Hg, Pb, Cd, and Cr) and one metaloid (As) were analyzed in shark livers using an atomic absorption spectrophotometry with flame and hydride generator. Our results showed that the maximum concentrations found were: Hg = 0.69 mg/kg, Cd = 0.43 mg/kg, As = 27.37 mg/kg, Cr = 0.70 mg/kg. The minimum concentrations found were: As = 14.91 mg/kg, Cr = 0.35 mg/kg. The Pb could not be determined because the samples did not have the spectrophotometer minimum detectable amount (0.1 mg/kg). None of the 19 samples analyzed showed above the permissible limits established by Mexican and American laws. There was a correlation between shark size and Cr and As concentration (Pearson test). The concentration of Cr and As was observed to be higher in bigger animals. There was not a significant difference in heavy metals concentration between juveniles and adults; however, there was a difference between males and females. A higher Cr concentration was found in females when compared to males. None of the samples exceed the maximum limit established by the laws of Mexico and the United States of America. Much longer studies are needed with C. limbatus and other species caught in the region, in order to determine the degree of contaminants exposure in aquatic ecosystems and to identify potential health risks to consumers.
Absorption of mercuric cation by tannins in agricultural residues

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

Waiss, A.C. Jr.; Wiley, M.E.; Kuhnle, J.A.

1973-01-01

Two common environmental pollutants are agricultural residues (skins, pits, husks, tannin bark, grape pomace) and waste streams of water containing only traces of heavy metals (such as mercury at 10 or more ppb) from mining or manufacturing operations. Agricultural residues contain tannins, polyphenolic substances, pectin, and other polymers-all with chemically reactive groups that can chelate, reduce, oxidize, demonstrate ion exchange properties, and aid in removing traces of heavy metals from dilute waste water streams at low cost. Finely ground and water-washed agricultural residues were slurried in water and packed into columns for absorption tests with heavy metals. Solutions of knownmore » concentrations of heavy metals were passed through the packed columns which were then eluted with water or with alkaline or acidic solutions. The fractions and the column absorbents were then analyzed by standard atomic absorption methods. The nature of the physical and chemical forces that are effective in metal absorption from agricultural residues is not clear.« less

Preliminary results from the heavy ions in space experiment

NASA Technical Reports Server (NTRS)

Adams, James H., Jr.; Beahm, Lorraine P.; Tylka, Allan J.

1992-01-01

The Heavy Ions In Space (HIIS) experiment has two primary objectives: (1) to measure the elemental composition of ultraheavy galactic cosmic rays, beginning in the tin-barium region of the periodic table; and (2) to study heavy ions which arrive at LDEF below the geomagnetic cutoff, either because they are not fully stripped of electrons or because their source is within the magnetosphere. Both of these objectives have practical as well as astrophysical consequences. In particular, the high atomic number of the ultraheavy galactic cosmic rays puts them among the most intensely ionizing particles in Nature. They are therefore capable of upsetting electronic components normally considered immune to such effects. The below cutoff heavy ions are intensely ionizing because of their low velocity. They can be a significant source of microelectronic anomalies in low inclination orbits, where Earth's magnetic field protects satellites from most particles from interplanetary space. The HIIS results will lead to significantly improved estimates of the intensely ionizing radiation environment.
Physics Division progress report for period ending June 30, 1981

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

Not Available

1981-11-01

Progress is reported in detail in the following areas: Holifield Heavy-Ion Research Facility, nuclear physics, the UNISOR program, neutron physics, theoretical physics, the Nuclear Data Project, atomic and plasma physics, and high energy physics. Publications are listed. Separate abstracts were prepared for 34 papers. (WHK)
A Simple DWBA (’Franck-Condon’) Treatment of H-Atom Transfers between Two Heavy Particles.

DTIC Science & Technology

1984-07-02

integral over the reactants’ and products’ wavefunctions and the interaction potential. )Permanent address: DIpartarnento de Quirnica Fisica y Quimica... Cuantica , USniversidad Autonomna de Madrid, Cantoblanco. Madrid-34, Spain. blContribution No. 7020. -2- The reactants’ and products’ wavelunctions
Positronium collisions with atoms and molecules

NASA Astrophysics Data System (ADS)

Fabrikant, I. I.; Gribakin, G. F.; Wilde, R. S.

2017-11-01

We review recent theoretical efforts to explain observed similarities between electron-atom and positronium(Ps)-atom scattering which also extends to molecular targets. In the range of the projectile velocities above the threshold for Ps ionization (break-up) this similarity can be explained in terms of quasi-free electron scattering and impulse approximation. However, for lower Ps velocities more sophisticated methods should be developed. Our calculations of Ps scattering by heavy noble-gas atoms agree well with experiments at Ps velocities above the Ps ionization threshold. However, in contrast to electron scattering cross sections, at lower velocities they exhibit maxima whereas the experimental cross sections tend to decrease toward lower velocities indicating the same similarity with electron scattering cross section observed above the threshold. Our preliminary results for Ps-N2 scattering confirm experimental observation of a resonance similar to the ∏ g resonance in electron-N2 scattering.
Observation of crystalline changes of titanium dioxide during lithium insertion by visible spectrum analysis.

PubMed

Nam, Inho; Park, Jongseok; Park, Soomin; Bae, Seongjun; Yoo, Young Geun; Han, Jeong Woo; Yi, Jongheop

2017-05-24

Real-time analysis of changes in the atomic environment of materials is a cutting edge technology that is being used to explain reaction dynamics in many fields of science. Previously, this kind of analysis was only possible using heavy nucleonic equipment such as XANES and EXAFS, or Raman spectroscopy on a moderate scale. Here, a new methodology is described that can be used to track changes in crystalline developments during complex Li insertion reactions via the observation of structural color. To be specific, the changes in atomic crystalline and nanostructure are shown during Li insertion in a complex TiO 2 polymorph. Structural color corresponds to the refractive indices of materials originating from their atomic bonding nature and precise wave interferences in accordance with their nanostructure. Therefore, this new analysis simultaneously reveals changes in the nanostructure as well as changes in the atomic bonding nature of materials.
Quantum oscillations of nitrogen atoms in uranium nitride

NASA Astrophysics Data System (ADS)

Aczel, A. A.; Granroth, G. E.; MacDougall, G. J.; Buyers, W. J. L.; Abernathy, D. L.; Samolyuk, G. D.; Stocks, G. M.; Nagler, S. E.

2012-10-01

The vibrational excitations of crystalline solids corresponding to acoustic or optic one-phonon modes appear as sharp features in measurements such as neutron spectroscopy. In contrast, many-phonon excitations generally produce a complicated, weak and featureless response. Here we present time-of-flight neutron scattering measurements for the binary solid uranium nitride, showing well-defined, equally spaced, high-energy vibrational modes in addition to the usual phonons. The spectrum is that of a single atom, isotropic quantum harmonic oscillator and characterizes independent motions of light nitrogen atoms, each found in an octahedral cage of heavy uranium atoms. This is an unexpected and beautiful experimental realization of one of the fundamental, exactly solvable problems in quantum mechanics. There are also practical implications, as the oscillator modes must be accounted for in the design of generation IV nuclear reactors that plan to use uranium nitride as a fuel.
Quantum oscillations of nitrogen atoms in uranium nitride.

PubMed

Aczel, A A; Granroth, G E; Macdougall, G J; Buyers, W J L; Abernathy, D L; Samolyuk, G D; Stocks, G M; Nagler, S E

2012-01-01

The vibrational excitations of crystalline solids corresponding to acoustic or optic one-phonon modes appear as sharp features in measurements such as neutron spectroscopy. In contrast, many-phonon excitations generally produce a complicated, weak and featureless response. Here we present time-of-flight neutron scattering measurements for the binary solid uranium nitride, showing well-defined, equally spaced, high-energy vibrational modes in addition to the usual phonons. The spectrum is that of a single atom, isotropic quantum harmonic oscillator and characterizes independent motions of light nitrogen atoms, each found in an octahedral cage of heavy uranium atoms. This is an unexpected and beautiful experimental realization of one of the fundamental, exactly solvable problems in quantum mechanics. There are also practical implications, as the oscillator modes must be accounted for in the design of generation IV nuclear reactors that plan to use uranium nitride as a fuel.
Many-Body Descriptors for Predicting Molecular Properties with Machine Learning: Analysis of Pairwise and Three-Body Interactions in Molecules.

PubMed

Pronobis, Wiktor; Tkatchenko, Alexandre; Müller, Klaus-Robert

2018-06-12

Machine learning (ML) based prediction of molecular properties across chemical compound space is an important and alternative approach to efficiently estimate the solutions of highly complex many-electron problems in chemistry and physics. Statistical methods represent molecules as descriptors that should encode molecular symmetries and interactions between atoms. Many such descriptors have been proposed; all of them have advantages and limitations. Here, we propose a set of general two-body and three-body interaction descriptors which are invariant to translation, rotation, and atomic indexing. By adapting the successfully used kernel ridge regression methods of machine learning, we evaluate our descriptors on predicting several properties of small organic molecules calculated using density-functional theory. We use two data sets. The GDB-7 set contains 6868 molecules with up to 7 heavy atoms of type CNO. The GDB-9 set is composed of 131722 molecules with up to 9 heavy atoms containing CNO. When trained on 5000 random molecules, our best model achieves an accuracy of 0.8 kcal/mol (on the remaining 1868 molecules of GDB-7) and 1.5 kcal/mol (on the remaining 126722 molecules of GDB-9) respectively. Applying a linear regression model on our novel many-body descriptors performs almost equal to a nonlinear kernelized model. Linear models are readily interpretable: a feature importance ranking measure helps to obtain qualitative and quantitative insights on the importance of two- and three-body molecular interactions for predicting molecular properties computed with quantum-mechanical methods.
Harmonic Dynamics of Proteins: Normal Modes and Fluctuations in Bovine Pancreatic Trypsin Inhibitor

NASA Astrophysics Data System (ADS)

Brooks, Bernard; Karplus, Martin

1983-11-01

A normal mode analysis making use of an empirical potential function including local and nonlocal (nonbonded) interactions is performed for the bovine pancreatic trypsin inhibitor in the full conformational space of the molecule (1,740 degrees of freedom); that is, all bond lengths and angles, as well as dihedral angles, are included for the 580-atom system consisting of all heavy atoms and polar hydrogens. The heavy-atom frequency spectrum shows a dense distribution between 3 and 1,800 cm-1, with 350 modes below 216 cm-1. Most of the low-frequency modes, of which many have significant anharmonic character, are found to be delocalized over the protein. The root-mean-square amplitudes of the atomic fluctuations are calculated at 300 K from the normal modes and compared with those obtained from a solution molecular dynamics simulation based on the same potential function; very good agreement is obtained for the variation in the main-chain fluctuations as a function of residue number, though larger differences occur for the side chains. The fluctuations are generally, though not always, dominated by frequencies below 30 cm-1, in accord with the results of the dynamics simulation. The vibrational contributions to the thermodynamic properties of the protein are calculated as a function of temperature; the effects of perturbations on the spectrum, suggested for ligand or substrate binding, are examined. The analysis demonstrates that, in spite of the anharmonic contributions to the potential, a normal mode description can provide useful results concerning the internal motions of proteins.
Topological vortex formation in a Bose-Einstein condensate under gravitational field

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

Kawaguchi, Yuki; Ohmi, Tetsuo; Nakahara, Mikio

2004-10-01

Topological phase imprinting is a unique technique for vortex formation in a Bose-Einstein condensate (BEC) of an alkali-metal gas, in that it does not involve rotation: the BEC is trapped in a quadrupole field with a uniform bias field which is reversed adiabatically leading to vortex formation at the center of the magnetic trap. The scenario has been experimentally verified by Leanhardt et al. employing {sup 23}Na atoms. Recently similar experiments have been conducted by Hirotani et al. in which a BEC of {sup 87}Rb atoms was used. In the latter experiments the authors found that fine-tuning of the fieldmore » reverse time T{sub rev} is required to achieve stable vortex formation. Otherwise, they often observed vortex fragmentation or a condensate without a vortex. It is shown in this paper that this behavior can be attributed to the heavy mass of the Rb atom. The confining potential, which depends on the eigenvalue m{sub B} of the hyperfine spin F along the magnetic field, is now shifted by the gravitational field perpendicular to the vortex line. Then the positions of two weak-field-seeking states with m{sub B}=1 and 2 deviate from each other. This effect is more prominent for BECs with a heavy atomic mass, for which the deviation is greater and, moreover, the Thomas-Fermi radius is smaller. We found, by solving the Gross-Pitaevskii equation numerically, that two condensates interact in a very complicated way leading to fragmentation of vortices, unless T{sub rev} is properly tuned.« less
Material discrimination using scattering and stopping of cosmic ray muons and electrons: Differentiating heavier from lighter metals as well as low-atomic weight materials

NASA Astrophysics Data System (ADS)

Blanpied, Gary; Kumar, Sankaran; Dorroh, Dustin; Morgan, Craig; Blanpied, Isabelle; Sossong, Michael; McKenney, Shawn; Nelson, Beth

2015-06-01

Reported is a new method to apply cosmic-ray tomography in a manner that can detect and characterize not only dense assemblages of heavy nuclei (like Special Nuclear Materials, SNM) but also assemblages of medium- and light-atomic-mass materials (such as metal parts, conventional explosives, and organic materials). Characterization may enable discrimination between permitted contents in commerce and contraband (explosives, illegal drugs, and the like). Our Multi-Mode Passive Detection System (MMPDS) relies primarily on the muon component of cosmic rays to interrogate Volumes of Interest (VOI). Muons, highly energetic and massive, pass essentially un-scattered through materials of light atomic mass and are only weakly scattered by conventional metals used in industry. Substantial scattering and absorption only occur when muons encounter sufficient thicknesses of heavy elements characteristic of lead and SNM. Electrons are appreciably scattered by light elements and stopped by sufficient thicknesses of materials containing medium-atomic-mass elements (mostly metals). Data include simulations based upon GEANT and measurements in the HMT (Half Muon Tracker) detector in Poway, CA and a package scanner in both Poway and Socorro NM. A key aspect of the present work is development of a useful parameter, designated the "stopping power" of a sample. The low-density regime, comprising organic materials up to aluminum, is characterized using very little scattering but a strong variation in stopping power. The medium-to-high density regime shows a larger variation in scattering than in stopping power. The detection of emitted gamma rays is another useful signature of some materials.
Heavy metal determinations in algae, mussels and clams. Their possible employment for assessing the sea water quality criteria

NASA Astrophysics Data System (ADS)

Locatelli, C.

2003-05-01

An empirical criterion for a possible classification of sea water quality is proposed. It is based on the knowledge of metal content in algae (Ulva Rigida) mussels (Mytilus Galloprovincialis) and clams (Tapes Philippinarum), three species present in marine ecosystems. The elements considered are Hg, Cu, Pb, Cd, Zn, Ni and Cr. The anatytical technique employed is Atomic Absorption Spectroscopy (AAS). The analytical procedure has been verified on three standard reference materials : Sea Water BCR-CRM 403, Ulva Lactuca BCR-CRM 279 and Mussel Tissue BCR-CRM 278. For all the elements, in addition to detection limits, accuracy and precision are given : the former, expressed as retative error (e). and the latter, expressed as relative standard deviation (sr), were in all cases lower than 6%.
Copper(II)-rubeanic acid coprecipitation system for separation-preconcentration of trace metal ions in environmental samples for their flame atomic absorption spectrometric determinations.

PubMed

Soylak, Mustafa; Erdogan, Nilgun D

2006-09-21

A simple and facile preconcentration procedure based on the coprecipitation of trace heavy metal ions with copper(II)-rubeanic acid complex has been developed. The analytical parameters including pH, amounts of rubeanic acid, sample volume, etc. was investigated for the quantitative recoveries of Pb(II), Fe(III), Cd(II), Au(III), Pd(II) and Ni(II). No interferic effects were observed from the concomitant ions. The detection limits for analyte ions by 3 sigma were in the range of 0.14 microg/l for iron-3.4 microg/l for lead. The proposed coprecipitation method was successfully applied to water samples from Palas Lake-Kayseri, soil and sediment samples from Kayseri and Yozgat-Turkey.
Rydberg series in the lanthanides and actinides observed by stepwise laser excitation

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

Worden, E.F.; Solarz, R.W.; Paisner, J.A.

1977-05-18

The techniques of stepwise laser excitation were applied to obtain Ryberg series in the lanthanides and in uranium. The methods employed circumvent many of the experimental difficulties inherent in conventional absorption spectrosopy of these heavy atoms with very complex spectra. The Rydberg series observed have allowed the determination of accurate ionization limits. The values in eV are: Ce, 5.5387(4);Nd, 5.5250(6); Sm, 5.6437(10); Eu, 5.6704(3); Gd, 6.1502(6); Tb, 5.8639(6); Dy, 5.9390(6); Ho, 6.0216(6); Er 6.1077(6); U, 6.1941(5). A comparison of the f/sup n/s/sup 2/-f/sup n/s ionization limits as a function of n with theoretical calculations is made.
Electronic Bandgap and Edge Reconstruction in Phosphorene Materials

DOE PAGES

Liang, Liangbo; Wang, Jun; Lin, Wenzhi; ...

2014-11-12

Single-layer black phosphorous (BP), or phosphorene, is a highly-anisotropic two-dimensional elemental material possessing promising semiconductor properties for flexible electronics. However, the direct bandgap of single-layer black phosphorus predicted theoretically has not been directly measured, and the properties of its edges have not been considered in detail. Here we report atomic scale electronic variation related to strain-induced anisotropic deformation of the puckered honeycomb structure of freshly cleaved black phosphorus using a highresolved scanning tunneling spectroscopy (STS) survey along the light (x) and heavy (y) effective mass directions. Through a combination of STS measurements and first-principles calculations, a model for edge reconstructionmore » is also determined. The reconstruction is shown to self-passivate any dangling bond by switching the oxidation state of phosphorous from +3 to +5.« less
Heavy metals in edible seaweeds commercialised for human consumption

NASA Astrophysics Data System (ADS)

Besada, Victoria; Andrade, José Manuel; Schultze, Fernando; González, Juan José

2009-01-01

Though seaweed consumption is growing steadily across Europe, relatively few studies have reported on the quantities of heavy metals they contain and/or their potential effects on the population's health. This study focuses on the first topic and analyses the concentrations of six typical heavy metals (Cd, Pb, Hg, Cu, Zn, total As and inorganic As) in 52 samples from 11 algae-based products commercialised in Spain for direct human consumption ( Gelidium spp.; Eisenia bicyclis; Himanthalia elongata; Hizikia fusiforme; Laminaria spp.; Ulva rigida; Chondrus crispus; Porphyra umbilicales and Undaria pinnatifida). Samples were ground, homogenised and quantified by atomic absorption spectrometry (Cu and Zn by flame AAS; Cd, Pb and total As by electrothermal AAS; total mercury by the cold vapour technique; and inorganic As by flame-hydride generation). Accuracy was assessed by participation in periodic QUASIMEME (Quality Assurance of Information in Marine Environmental Monitoring in Europe) and IAEA (International Atomic Energy Agency) intercalibration exercises. To detect any objective differences existing between the seaweeds' metal concentrations, univariate and multivariate studies (principal component analysis, cluster analysis and linear discriminant analysis) were performed. It is concluded that the Hizikia fusiforme samples contained the highest values of total and inorganic As and that most Cd concentrations exceeded the French Legislation. The two harvesting areas (Atlantic and Pacific oceans) were differentiated using both univariate studies (for Cu, total As, Hg and Zn) and a multivariate discriminant function (which includes Zn, Cu and Pb).
The interplay of hydrogen bonding and dispersion in phenol dimer and trimer: structures from broadband rotational spectroscopy.

PubMed

Seifert, Nathan A; Steber, Amanda L; Neill, Justin L; Pérez, Cristóbal; Zaleski, Daniel P; Pate, Brooks H; Lesarri, Alberto

2013-07-21

The structures of the phenol dimer and phenol trimer complexes in the gas phase have been determined using chirped-pulse Fourier transform microwave spectroscopy in the 2-8 GHz band. All fourteen (13)C and (18)O phenol dimer isotopologues were assigned in natural abundance. A full heavy atom experimental substitution structure was determined, and a least-squares fit ground state r0 structure was determined by proper constraint of the M06-2X/6-311++g(d,p) ab initio structure. The structure of phenol dimer features a water dimer-like hydrogen bond, as well as a cooperative contribution from inter-ring dispersion. Comparisons between the experimental structure and previously determined experimental structures, as well as ab initio structures from various levels of theory, are discussed. For phenol trimer, a C3 symmetric barrel-like structure is found, and an experimental substitution structure was determined via measurement of the six unique (13)C isotopologues. The least-squares fit rm((1)) structure reveals a similar interplay between hydrogen bonding and dispersion in the trimer, with water trimer-like hydrogen bonding and C-H···π interactions.
Anthropogenic sources and environmentally relevant concentrations of heavy metals in surface water of a mining district in Ghana: a multivariate statistical approach.

PubMed

Armah, Frederick A; Obiri, Samuel; Yawson, David O; Onumah, Edward E; Yengoh, Genesis T; Afrifa, Ernest K A; Odoi, Justice O

2010-11-01

The levels of heavy metals in surface water and their potential origin (natural and anthropogenic) were respectively determined and analysed for the Obuasi mining area in Ghana. Using Hawth's tool an extension in ArcGIS 9.2 software, a total of 48 water sample points in Obuasi and its environs were randomly selected for study. The magnitude of As, Cu, Mn, Fe, Pb, Hg, Zn and Cd in surface water from the sampling sites were measured by flame Atomic Absorption Spectrophotometry (AAS). Water quality parameters including conductivity, pH, total dissolved solids and turbidity were also evaluated. Principal component analysis and cluster analysis, coupled with correlation coefficient analysis, were used to identify possible sources of these heavy metals. Pearson correlation coefficients among total metal concentrations and selected water properties showed a number of strong associations. The results indicate that apart from tap water, surface water in Obuasi has elevated heavy metal concentrations, especially Hg, Pb, As, Cu and Cd, which are above the Ghana Environmental Protection Agency (GEPA) and World Health Organisation (WHO) permissible levels; clearly demonstrating anthropogenic impact. The mean heavy metal concentrations in surface water divided by the corresponding background values of surface water in Obuasi decrease in the order of Cd > Cu > As > Pb > Hg > Zn > Mn > Fe. The results also showed that Cu, Mn, Cd and Fe are largely responsible for the variations in the data, explaining 72% of total variance; while Pb, As and Hg explain only 18.7% of total variance. Three main sources of these heavy metals were identified. As originates from nature (oxidation of sulphide minerals particularly arsenopyrite-FeAsS). Pb derives from water carrying drainage from towns and mine machinery maintenance yards. Cd, Zn, Fe and Mn mainly emanate from industry sources. Hg mainly originates from artisanal small-scale mining. It cannot be said that the difference in concentration of heavy metals might be attributed to difference in proximity to mining-related activities because this is inconsistent with the cluster analysis. Based on cluster analysis SN32, SN42 and SN43 all belong to group one and are spatially similar. But the maximum Cu concentration was found in SN32 while the minimum Cu concentration was found in SN42 and SN43.
[Determination of deuterium concentration in foods and influence of water with modified isotopic composition on oxidation parameters and heavy hydrogen isotopes content in experimental animals].

PubMed

Basov, A A; Bykov, I M; Baryshev, M G; Dzhimak, S S; Bykov, M I

2014-01-01

The article presents the results of the study of the deuterium (D) content in food products as well as the influence of deuterium depleted water (DDW) on the concentration of heavy hydrogen isotopes in the blood and lyophilized tissues of rats. The most significant difference in the content of D was found between potato and pork fat, which indexes the standard delta notation (δ) D in promille, related to the international standard SMOW (Standard Mean Ocean of Water) amounted to -83,2 per thousand and -250,7 per thousand, respectively (p<0,05). Among the investigated samples of water deuterium concentration ranged from -75,5 per thousand (Narzan) to +72,1 per thousand (Kubai), that indicates the ability of some food products to increase the concentration of heavy hydrogen atoms in the body. The data obtained in the experimental modeling of the diet of male Wistar rats in the age of 5-6 mo (weight 235 ± 16 g) using DDW (δD = -743,2 per thousand) instead of drinking water (δD = -37,0 per thousand) with identical mineral composition showed that after 2 weeks significant (p <0,05) formation of isotopic (deuterium-protium, D/H) gradient in the body is possible. Changing the direction of isotopic D/H gradient in laboratory animals in comparison with its physiological indicators (72-127 per thousand, "plasma>tissue") is due to different rates ofisotopic exchange reactions in plasma and tissues (liver, kidney, heart), which can be explained by entering into the composition of a modified diet of organic substrates with more than DDW concentration D, which are involved in the construction of cellular structures and eventually lead to a redistribution of D and change direction of D/H gradient "plasma
Physical particularities of nuclear reactors using heavy moderators of neutrons

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

Kulikov, G. G., E-mail: ggkulikov@mephi.ru; Shmelev, A. N.

2016-12-15

In nuclear reactors, thermal neutron spectra are formed using moderators with small atomic weights. For fast reactors, inserting such moderators in the core may create problems since they efficiently decelerate the neutrons. In order to form an intermediate neutron spectrum, it is preferable to employ neutron moderators with sufficiently large atomic weights, using {sup 233}U as a fissile nuclide and {sup 232}Th and {sup 231}Pa as fertile ones. The aim of the work is to investigate the properties of heavy neutron moderators and to assess their advantages. The analysis employs the JENDL-4.0 nuclear data library and the SCALE program packagemore » for simulating the variation of fuel composition caused by irradiation in the reactor. The following main results are obtained. By using heavy moderators with small neutron moderation steps, one is able to (1) increase the rate of resonance capture, so that the amount of fertile material in the fuel may be reduced while maintaining the breeding factor of the core; (2) use the vacant space for improving the fuel-element properties by adding inert, strong, and thermally conductive materials and by implementing dispersive fuel elements in which the fissile material is self-replenished and neutron multiplication remains stable during the process of fuel burnup; and (3) employ mixtures of different fertile materials with resonance capture cross sections in order to increase the resonance-lattice density and the probability of resonance neutron capture leading to formation of fissile material. The general conclusion is that, by forming an intermediate neutron spectrum with heavy neutron moderators, one can use the fuel more efficiently and improve nuclear safety.« less

Evaluation of shielding parameters for heavy metal fluoride based tellurite-rich glasses for gamma ray shielding applications

NASA Astrophysics Data System (ADS)

Sayyed, M. I.; Lakshminarayana, G.; Kityk, I. V.; Mahdi, M. A.

2017-10-01

In this work, we have evaluated the γ-ray shielding parameters such as mass attenuation coefficient (μ/ρ), effective atomic number (Zeff), half value layer (HVL), mean free path (MFP) and exposure buildup factors (EBF) for heavy metal fluoride (PbF2) based tellurite-rich glasses. In addition, neutron total macroscopic cross sections (∑R) for these glasses were also calculated. The maximum value for μ/ρ, Zeff and ∑R was found for heavy metal (Bi2O3) oxide introduced glass. The results of the selected glasses have been compared, in terms of MFP with different glass systems. The shielding effectiveness of the selected glasses is found comparable or better than of common ones, which indicates that these glasses with suitable oxides could be developed for gamma ray shielding applications.
Dosimetry of heavy ions by use of CCD detectors

NASA Technical Reports Server (NTRS)

Schott, J. U.

1994-01-01

The design and the atomic composition of Charge Coupled Devices (CCD's) make them unique for investigations of single energetic particle events. As detector system for ionizing particles they detect single particles with local resolution and near real time particle tracking. In combination with its properties as optical sensor, particle transversals of single particles are to be correlated to any objects attached to the light sensitive surface of the sensor by simple imaging of their shadow and subsequent image analysis of both, optical image and particle effects, observed in affected pixels. With biological objects it is possible for the first time to investigate effects of single heavy ions in tissue or extinguished organs of metabolizing (i.e. moving) systems with a local resolution better than 15 microns. Calibration data for particle detection in CCD's are presented for low energetic protons and heavy ions.
Means for obtaining a metal ion beam from a heavy-ion cyclotron source

DOEpatents

Hudson, E.D.; Mallory, M.L.

1975-08-01

A description is given of a modification to a cyclotron ion source used in producing a high intensity metal ion beam. A small amount of an inert support gas maintains the usual plasma arc, except that it is necessary for the support gas to have a heavy mass, e.g., xenon or krypton as opposed to neon. A plate, fabricated from the metal (or anything that can be sputtered) to be ionized, is mounted on the back wall of the ion source arc chamber and is bombarded by returning energetic low-charged gas ions that fail to cross the initial accelerating gap between the ion source and the accelerating electrode. Some of the atoms that are dislodged from the plate by the returning gas ions become ionized and are extracted as a useful beam of heavy ions. (auth)
High baryon densities in heavy ion collisions at energies attainable at the BNL Relativistic Heavy-Ion Collider and the CERN Large Hadron Collider

NASA Astrophysics Data System (ADS)

Li, Ming; Kapusta, Joseph I.

2017-01-01

In very high-energy collisions nuclei are practically transparent to each other but produce very hot nearly baryon-free matter in the so-called central rapidity region. The energy in the central rapidity region comes from the kinetic energy of the colliding nuclei. We calculate the energy and rapidity loss of the nuclei using the color glass condensate model. This model also predicts the excitation energy of the nuclear fragments. Using a space-time picture of the collision we calculate the baryon and energy densities of the receding baryonic fireballs. For central collisions of gold nuclei at the highest energy attainable at the Relativistic Heavy-Ion Collider, for example, we find baryon densities more than ten times that of atomic nuclei over a large volume.
Monte-Carlo Simulations of Heavy Ions Track Structures and Applications

NASA Technical Reports Server (NTRS)

Plante, Ianik; Cucinotta, Francia A.

2013-01-01

In space, astronauts are exposed to protons, high ]energy heavy (HZE) ions that have a high charge (Z) and energy (E), and secondary radiation, including neutrons and recoil nuclei produced by nuclear reactions in spacecraft walls or in tissue. The astronauts can only be partly shielded from these particles. Therefore, on travelling to Mars, it is estimated that every cell nucleus in an astronaut fs body would be hit by a proton or secondary electron (e.g., electrons of the target atoms ionized by the HZE ion) every few days and by an HZE ion about once a month. The risks related to these heavy ions are not well known and of concern for long duration space exploration missions. Medical ion therapy is another situation where human beings can be irradiated by heavy ions, usually to treat cancer. Heavy ions have a peculiar track structure characterized by high levels of energy ]deposition clustering, especially in near the track ends in the so ]called eBragg peak f region. In radiotherapy, these features of heavy ions can provide an improved dose conformation with respect to photons, also considering that the relative biological effectiveness (RBE) of therapeutic ions in the plateau region before the peak is sufficiently low. Therefore, several proton and carbon ion therapy facilities are under construction at this moment
Dynamic Effects in the Photoionization of the 6s Subshell of Radon and Nobelium

NASA Astrophysics Data System (ADS)

Keating, David; Manson, Steven; Deshmukh, Pranawa

2017-04-01

Relativistic interactions are very important contributors to atomic properties. Of interest is the alterations made to the wave functions, i.e., the dynamics. These dynamical changes can greatly affect the photoionization cross section of heavy (high Z) atoms. To explore the extent of these dynamic effects a theoretical study of the 6s photoionization cross section of both radon (Z = 86) and nobelium (Z = 102) have been performed using the relativistic random phase approximation (RRPA) methodology. These two cases have been selected because they offer the clearest picture of the effects in question. In order to determine which features in the photoionization cross section are due to relativity, calculations using the (nonrelativistic) random phase approximation with exchange method (RPAE) are performed for comparison. Interchannel coupling can obscure the dynamic effects by ``pulling'' minima out of the discrete spectrum and into the continuum or by inducing minima. Therefore it is necessary to perform calculations without coupling included. This is possible thanks to the RRPA and RPAE codes being able to calculate cross sections with particular channels omitted. Comparisons are presented between calculations with and without interchannel coupling. Work supported by DOE and NSF.
Determination of mercury by cold vapor atomic absorption spectrophotometer in Tongkat Ali preparations obtained in Malaysia.

PubMed

Ang, Hooi-Hoon; Lee, Ee-Lin; Cheang, Hui-Seong

2004-01-01

The DCA (Drug Control Authority), Malaysia, has implemented the phase 3 registration of traditional medicines on 1 January 1992, with special emphasis on the quality, efficacy, and safety (including the presence of heavy metals) in all pharmaceutical dosage forms of traditional medicine preparations. As such, a total of 100 products in various pharmaceutical dosage forms of a herbal preparation, containing Tongkat Ali, were analyzed for mercury content using cold vapor atomic absorption spectrophotometer. Results showed that 36% of the above products possessed 0.52 to 5.30 ppm of mercury and, therefore, do not comply with the quality requirement for traditional medicines in Malaysia. Out of these 36 products, 5 products that possessed 1.05 to 4.41 ppm of mercury were in fact have already registered with the DCA, Malaysia. However, the rest of the products that contain 0.52 to 5.30 ppm of mercury still have not registered with the DCA, Malaysia. Although this study showed that only 64% of the products complied with the quality requirement for traditional medicines in Malaysia pertaining to mercury, they cannot be assumed safe from mercury contamination because of batch-to-batch inconsistency.
Determination of the conformational ensemble of the TAR RNA by X-ray scattering interferometry

PubMed Central

Walker, Peter

2017-01-01

Abstract The conformational ensembles of structured RNA's are crucial for biological function, but they remain difficult to elucidate experimentally. We demonstrate with HIV-1 TAR RNA that X-ray scattering interferometry (XSI) can be used to determine RNA conformational ensembles. X-ray scattering interferometry (XSI) is based on site-specifically labeling RNA with pairs of heavy atom probes, and precisely measuring the distribution of inter-probe distances that arise from a heterogeneous mixture of RNA solution structures. We show that the XSI-based model of the TAR RNA ensemble closely resembles an independent model derived from NMR-RDC data. Further, we show how the TAR RNA ensemble changes shape at different salt concentrations. Finally, we demonstrate that a single hybrid model of the TAR RNA ensemble simultaneously fits both the XSI and NMR-RDC data set and show that XSI can be combined with NMR-RDC to further improve the quality of the determined ensemble. The results suggest that XSI-RNA will be a powerful approach for characterizing the solution conformational ensembles of RNAs and RNA-protein complexes under diverse solution conditions. PMID:28108663
Mechanistic investigations of the hydrolysis of amides, oxoesters and thioesters via kinetic isotope effects and positional isotope exchange.

PubMed

Robins, Lori I; Fogle, Emily J; Marlier, John F

2015-11-01

The hydrolysis of amides, oxoesters and thioesters is an important reaction in both organic chemistry and biochemistry. Kinetic isotope effects (KIEs) are one of the most important physical organic methods for determining the most likely transition state structure and rate-determining step of these reaction mechanisms. This method induces a very small change in reaction rates, which, in turn, results in a minimum disturbance of the natural mechanism. KIE studies were carried out on both the non-enzymatic and the enzyme-catalyzed reactions in an effort to compare both types of mechanisms. In these studies the amides and esters of formic acid were chosen because this molecular structure allowed development of methodology to determine heavy-atom solvent (nucleophile) KIEs. This type of isotope effect is difficult to measure, but is rich in mechanistic information. Results of these investigations point to transition states with varying degrees of tetrahedral character that fit a classical stepwise mechanism. This article is part of a special issue entitled: Enzyme Transition States from Theory and Experiment. Copyright © 2014 Elsevier B.V. All rights reserved.
Division B Commission 14 Working Group: Collision Processes

NASA Astrophysics Data System (ADS)

Peach, Gillian; Dimitrijevic, Milan S.; Barklem, Paul S.

2016-04-01

Since our last report (Peach & Dimitrijević 2012), a large number of new publications on the results of research in atomic and molecular collision processes and spectral line broadening have been published. Due to the limited space available, we have only included work of importance for astrophysics. Additional relevant papers, not included in this report, can be found in the databases at the web addresses provided in Section 6. Elastic and inelastic collisions between electrons, atoms, ions, and molecules are included, as well as charge transfer in collisions between heavy particles which can be very important.
Target Z dependence of Xe L x-ray emission in heavy ion-atom collision near the Bohr velocity: influence of level matching

NASA Astrophysics Data System (ADS)

Ren, Jieru; Zhao, Yongtao; Zhou, Xianming; Cheng, Rui; Lei, Yu; Sun, Yuanbo; Wang, Xing; Xu, Ge; Wang, Yuyu; Liu, Shidong; Yu, Yang; Li, Yongfeng; Zhang, Xiaoan; Xu, Zhongfeng; Xiao, Guoqing

2013-09-01

X-ray yields for the projectile L-shell have been measured for collisions between Xe20+ and thick solid targets throughout the periodic table with incident energies near the Bohr velocity. The yields show a very pronounced cyclic dependence on the target atomic number. This result indicates that Xe L x-ray emission intensity is greatly enhanced either in near-symmetric collisions or if the binding energy of the Xe M-shell matches the L- or N-shell binding energy of the target.
Do stellar and nebular abundances in the Cocoon nebula agree?

NASA Astrophysics Data System (ADS)

García-Rojas, J.; Simón-Díaz, S.; Esteban, C.

2015-05-01

The Cocoon nebula is an apparently spherical Galactic HII region ionized by a single star (BD+46 3474). This nebula seems to be appropriate to investigate the chemical behavior of oxygen and other heavy elements from two different points of view: a detailed analysis of the chemical content of the ionized gas through nebular spectrophotometry and a detailed spectroscopic analysis of the spectrum of the ionizing star using the state-of-the-art stellar atmosphere modelling. In this poster we present the results from a set of high-quality observations, from 2m-4m class telescopes, including the optical spectrum of the ionizing star BD+46 3474, along with long-slit spatially resolved spectroscopy of the nebula. We have used state-of-the-art stellar atmosphere codes to determine stellar parameters and the chemical content of several heavy elements. Traditional nebular techniques along with updated atomic data have been used to compute gaseous abundances of O, N and S in the Cocoon nebula. Thanks to the low ionization degree of the nebula, we could determine total abundances directly from observable ions (no ionization correction factors were needed) for three of the analyzed elements (O, S, and N). The derived stellar and nebular abundances are compared and the influence of the possible presence of the so-called temperature fluctuations on the nebula is discussed. The results of this study are presented in more detail in García-Rojas, Simón-Díaz & Esteban 2014, A&A, 571, A93.
The Smallest Drops of the Hottest Matter? New Investigations at the Relativistic Heavy Ion Collider (493rd Brookhaven Lecture)

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

Sickles, Anne

2014-03-19

Pool sharks at the billiards hall know that sometimes you aim to rocket the cue ball for a head-on collision, and other times, a mere glance will do. Physicists need to know more than a thing or two about collision geometry too, as they sift through data from the billions of ions that smash together at the Relativistic Heavy Ion Collider (RHIC). Determining whether ions crash head-on or just glance is crucial for the physicists analyzing data to study quark-gluon plasma—the ultra-hot, "perfect" liquid of quarks and gluons that existed more than 13 billion years ago, before the first protonsmore » and neutrons formed. For these physicists, collision geometry data provides insights about quark-gluon plasma's extremely low viscosity and other unusual properties, which are essential for understanding more about the "strong force" that holds together the nucleus, protons, and neutrons of every atom in the universe. Dr. Sickles explains how physicists use data collected at house-sized detectors like PHENIX and STAR to determine what happens before, during, and after individual particle collisions among billions at RHIC. She also explains how the ability to collide different "species" of nuclei at RHIC—including protons and gold ions today and possibly more with a proposed future electron-ion collider upgrade (eRHIC)—enables physicists to probe deeper into the mysteries of quark-gluon plasma and the strong force.« less
Heavy metal determinations in algae and clams and their possible employment for assessing the sea water quality criteria.

PubMed

Locatelli, C; Fabbri, D; Torsi, G

2001-01-01

An empirical criterion for a possible classification of sea water quality is proposed. It is based on the knowledge of metal content in algae (Ulva Rigida) and clams (Tapes Philippinarum), two species present in marine ecosystems. The elements considered are Hg, Cu, Pb, Cd, Zn. The analytical technique employed is Differential Pulse Anodic Stripping Voltammetry (DPASV) in the case of Cu, Pb, Cd, Zn, while the determination of mercury is obtained by the Cold Vapour Atomic Absorption Spectroscopy (CV-AAS) technique with SnCl2 as reducing agent. The analytical procedure has been verified on three standard reference materials: Sea Water BCR-CRM 403, Ulva Lactuca BCR-CRM 279 and Mussel Tissue BCR-CRM 278. For all the elements, in addition to detection limits, accuracy and precision are given: the former, expressed as relative error (e), and the latter, expressed as relative standard deviation (Sr), were in all cases lower than 6%.
Thiopental and Phenytoin as Novel Ionophores for Potentiometric Determination of Lead (II) Ions

PubMed Central

Rizk, Nashwa M.H.; Abbas, Samah S.; Hamza, Salem M.; Abd EL-Karem, Yasser M.

2009-01-01

Two novel polymeric membrane sensors for the analysis of Pb(II) have been developed based on two therapeutic drugs, thiopental (TP) and phenytoin (PT) as two new ionophores and potassium tetrakis(p-chlorophenyl) borate (KTpClPB) as a lipophilic additive, in plasticized PVC membranes. The sensors show a Nernstian response for Pb(II) ions over the wide concentration ranges of 1×10−2 – 7×10−6 M and 1×10−2 – 8×10−6 M for the sensors based on thiopental and phenytoin, respectively. The proposed sensors have a fast response time and can be used for more than nine weeks without any considerable divergence in potentials. The sensors exhibit comparatively good selectivity with respect to alkaline, alkaline earth and some transition and heavy metal ions. They were employed for direct determination of lead in solder alloys and in galena rocks with a good agreement with the obtained results by atomic absorption spectroscopy. PMID:22573991
Crystallization of isoelectrically homogeneous cholera toxin

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

Spangler, B.D.; Westbrook, E.M.

1989-02-07

Past difficulty in growing good crystals of cholera toxin has prevented the study of the crystal structure of this important protein. The authors have determined that failure of cholera toxin to crystallize well has been due to its heterogeneity. They have now succeeded in overcoming the problem by isolating a single isoelectric variant of this oligomeric protein (one A subunit and five B subunits). Cholera toxin purified by their procedure readily forms large single crystals. The crystal form has been described previously. They have recorded data from native crystals of cholera toxin to 3.0-{angstrom} resolution with our electronic area detectors.more » With these data, they have found the orientation of a 5-fold symmetry axis within these crystals, perpendicular to the screw dyad of the crystal. They are now determining the crystal structure of cholera toxin by a combination of multiple heavy-atom isomorphous replacement and density modification techniques, making use of rotational 5-fold averaging of the B subunits.« less
A molecular modeling based method to predict elution behavior and binding patches of proteins in multimodal chromatography.

PubMed

Banerjee, Suvrajit; Parimal, Siddharth; Cramer, Steven M

2017-08-18

Multimodal (MM) chromatography provides a powerful means to enhance the selectivity of protein separations by taking advantage of multiple weak interactions that include electrostatic, hydrophobic and van der Waals interactions. In order to increase our understanding of such phenomena, a computationally efficient approach was developed that combines short molecular dynamics simulations and continuum solvent based coarse-grained free energy calculations in order to study the binding of proteins to Self Assembled Monolayers (SAM) presenting MM ligands. Using this method, the free energies of protein-MM SAM binding over a range of incident orientations of the protein can be determined. The resulting free energies were then examined to identify the more "strongly bound" orientations of different proteins with two multimodal surfaces. The overall free energy of protein-MM surface binding was then determined and correlated to retention factors from isocratic chromatography. This correlation, combined with analytical expressions from the literature, was then employed to predict protein gradient elution salt concentrations as well as selectivity reversals with different MM resin systems. Patches on protein surfaces that interacted strongly with MM surfaces were also identified by determining the frequency of heavy atom contacts with the atoms of the MM SAMs. A comparison of these patches to Electrostatic Potential and hydrophobicity maps indicated that while all of these patches contained significant positive charge, only the highest frequency sites also possessed hydrophobicity. The ability to identify key binding patches on proteins may have significant impact on process development for the separation of bioproduct related impurities. Copyright © 2017 Elsevier B.V. All rights reserved.
Influence of heavy metal stress on antioxidant status and DNA damage in Urtica dioica.

PubMed

Gjorgieva, Darinka; Kadifkova Panovska, Tatjana; Ruskovska, Tatjana; Bačeva, Katerina; Stafilov, Trajče

2013-01-01

Heavy metals have the potential to interact and induce several stress responses in the plants; thus, effects of heavy metal stress on DNA damages and total antioxidants level in Urtica dioica leaves and stems were investigated. The samples are sampled from areas with different metal exposition. Metal content was analyzed by Inductively Coupled Plasma-Atomic Emission Spectrometer (ICP-AES), for total antioxidants level assessment the Ferric-Reducing Antioxidant Power (FRAP) assay was used, and genomic DNA isolation from frozen plant samples was performed to obtain DNA fingerprints of investigated plant. It was found that heavy metal contents in stems generally changed synchronously with those in leaves of the plant, and extraneous metals led to imbalance of mineral nutrient elements. DNA damages were investigated by Random Amplified Polymorphic DNA (RAPD) technique, and the results demonstrated that the samples exposed to metals yielded a large number of new fragments (total 12) in comparison with the control sample. This study showed that DNA stability is highly affected by metal pollution which was identified by RAPD markers. Results suggested that heavy metal stress influences antioxidant status and also induces DNA damages in U. dioica which may help to understand the mechanisms of metals genotoxicity.
Biosorption of heavy metals by obligate halophilic fungi.

PubMed

Bano, Amna; Hussain, Javaid; Akbar, Ali; Mehmood, Khalid; Anwar, Muhammad; Hasni, Muhammad Sharif; Ullah, Sami; Sajid, Sumbal; Ali, Imran

2018-05-01

The presence of heavy metals in the environment poses a serious threat to human health. Remediation of this problem using microorganisms has been widely researched to find a sustainable solution. Obligate halophilic fungi comprising Aspergillus flavus, Aspergillus gracilis, Aspergillus penicillioides (sp. 1), Aspergillus penicillioides (sp. 2), Aspergillus restrictus and Sterigmatomyces halophilus were used for the biosorption of cadmium, copper, ferrous, manganese, lead and zinc. The metals were supplemented as salts in potato dextrose broth for the growth of obligate halophilic fungi and incubated for 14 days. The supernatant and biomass were obtained by the acid digestion method. The biosorption was screened by atomic absorption spectroscopy. All tested fungi showed moderate to high adsorption of heavy metals, amongst which A. flavus and S. halophilus showed the best average adsorption of all heavy metals studied, with an average of 86 and 83%, respectively. On average, Fe and Zn are best removed from the liquid media of obligate halophilic fungi, with an average of 85 and 84%, respectively. This pioneering study of biosorption by obligate halophilic fungi using inexpensive media in stagnant conditions provides a cost-effective environmental solution for the removal of heavy metals. Copyright © 2018 Elsevier Ltd. All rights reserved.
Orbital order and effective mass enhancement in t2 g two-dimensional electron gases

NASA Astrophysics Data System (ADS)

Tolsma, John; Principi, Alessandro; Polini, Marco; MacDonald, Allan

2015-03-01

It is now possible to prepare d-electron two-dimensional electron gas systems that are confined near oxide heterojunctions and contain t2 g electrons with a density much smaller than one electron per metal atom. I will discuss a generic model that captures all qualitative features of electron-electron interaction physics in t2 g two-dimensional electron gas systems, and the use of a GW approximation to explore t2 g quasiparticle properties in this new context. t2 g electron gases contain a high density isotropic light mass xy component and low-density xz and yz anisotropic components with light and heavy masses in orthogonal directions. The high density light mass band screens interactions within the heavy bands. As a result the wave vector dependence of the self-energy is reduced and the effective mass is increased. When the density in the heavy bands is low, the difference in anisotropy between the two heavy bands favors orbital order. When orbital order does not occur, interactions still reshape the heavy-band Fermi surfaces. I will discuss these results in the context of recently reported magnetotransport experiments.

Heavy-metal detectors based on modified ferrite nanoparticles

PubMed Central

Klekotka, Urszula; Wińska, Ewelina; Zambrzycka-Szelewa, Elżbieta; Satuła, Dariusz

2018-01-01

In this work, we analyze artificial heavy-metal solutions with ferrite nanoparticles. Measurements of adsorption effectiveness of different kinds of particles, pure magnetite or magnetite doped with calcium, cobalt, manganese, or nickel ions, were carried out. A dependence of the adsorption efficiency on the composition of the inorganic core has been observed. Ferrites surfaces were modified by phthalic anhydride (PA), succinic anhydride (SA), acetic anhydride (AA), 3-phosphonopropionic acid (3-PPA), or 16-phosphohexadecanoic acid (16-PHDA) to compare the adsorption capability of the heavy metals Cd, Cu and Pb. The obtained nanoparticles were structurally characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Mössbauer spectroscopy. The amounts of Cd, Cu and Pb were measured out by atomic absorption spectroscopy (AAS) and energy dispersive X-ray (EDX) as comparative techniques. The performed study shows that SA linker appears to be the most effective in the adsorption of heavy metals. Moreover, regarding the influence of the composition of the inorganic core on the detection ability, the most effective ferrite Mn0.5Fe2.5O4 was selected for discussion. The highest heavy-metal adsorption capability and universality was observed for SA as a surface modifier. PMID:29600137
Heavy-metal detectors based on modified ferrite nanoparticles.

PubMed

Klekotka, Urszula; Wińska, Ewelina; Zambrzycka-Szelewa, Elżbieta; Satuła, Dariusz; Kalska-Szostko, Beata

2018-01-01

In this work, we analyze artificial heavy-metal solutions with ferrite nanoparticles. Measurements of adsorption effectiveness of different kinds of particles, pure magnetite or magnetite doped with calcium, cobalt, manganese, or nickel ions, were carried out. A dependence of the adsorption efficiency on the composition of the inorganic core has been observed. Ferrites surfaces were modified by phthalic anhydride (PA), succinic anhydride (SA), acetic anhydride (AA), 3-phosphonopropionic acid (3-PPA), or 16-phosphohexadecanoic acid (16-PHDA) to compare the adsorption capability of the heavy metals Cd, Cu and Pb. The obtained nanoparticles were structurally characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Mössbauer spectroscopy. The amounts of Cd, Cu and Pb were measured out by atomic absorption spectroscopy (AAS) and energy dispersive X-ray (EDX) as comparative techniques. The performed study shows that SA linker appears to be the most effective in the adsorption of heavy metals. Moreover, regarding the influence of the composition of the inorganic core on the detection ability, the most effective ferrite Mn 0.5 Fe 2.5 O 4 was selected for discussion. The highest heavy-metal adsorption capability and universality was observed for SA as a surface modifier.
Production, formation, and transport of high-brightness atomic hydrogen beam studies for the relativistic heavy ion collider polarized source upgrade.

PubMed

Kolmogorov, A; Atoian, G; Davydenko, V; Ivanov, A; Ritter, J; Stupishin, N; Zelenski, A

2014-02-01

The RHIC polarized H(-) ion source had been successfully upgraded to higher intensity and polarization by using a very high brightness fast atomic beam source developed at BINP, Novosibirsk. In this source the proton beam is extracted by a four-grid multi-aperture ion optical system and neutralized in the H2 gas cell downstream from the grids. The proton beam is extracted from plasma emitter with a low transverse ion temperature of ∼0.2 eV which is formed by plasma jet expansion from the arc plasma generator. The multi-hole grids are spherically shaped to produce "geometrical" beam focusing. Proton beam formation and transport of atomic beam were experimentally studied at test bench.
Measurements of the structure of an ionizing shock wave in a hydrogen-helium mixture

NASA Technical Reports Server (NTRS)

Leibowitz, L. P.

1972-01-01

Shock structure during ionization of a hydrogen-helium mixture was studied using hydrogen line and continuum emission measurements. A reaction scheme is proposed which includes hydrogen dissociation and a two-step excitation-ionization mechanism for hydrogen ionization by atom-atom and atom-electron collisions. Agreement was achieved between numerical calculations and measurements of emission intensity as a function of time for shock velocities from 13 to 20 km/sec in a 0.208 H2 - 0.792 He mixture. The electron temperature was found to be significantly different from the heavy particle temperature during much of the ionization process. Similar time histories for H beta and continuum emission indicate upper level populations of hydrogen in equilibrium with the electron concentration during the relaxation process.
Measurements of the structure of an ionizing shock wave in a hydrogen-helium mixture.

NASA Technical Reports Server (NTRS)

Leibowitz, L. P.

1973-01-01

Shock structure during ionization of a hydrogen-helium mixture has been followed using hydrogen line and continuum emission measurements. A reaction scheme is proposed which includes hydrogen dissociation and a two-step excitation-ionization mechanism for hydrogen ionization by atom-atom and atom-electron collisions. Agreement has been achieved between numerical calculations and measurements of emission intensity as a function of time for shock velocities from 13 to 20 km/sec in a 0.208 H2-0.792 He mixture. The electron temperature was found to be significantly different from the heavy particle temperature during much of the ionization process. Similar time histories for H beta and continuum emission indicate upper level populations of hydrogen in equilibrium with the electron concentration during the relaxation process.
Edwin M. McMillan

Science.gov Websites

mixture. The separation of the different components in these compound earths has been no easy task, since terbium and dysprosium in the lanthanides. By irradiating different sorts of heavy atoms with neutrons Berkeley Lab Search Submit Web People Close About the Lab Leadership/Organization Calendar News Center
Physics division progress report for period ending September 30 1991

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

Livingston, A.B.

1992-03-01

This report discusses research being conducted at Oak Ridge National Laboratory in physics. The areas covered are: Holifield Heavy Ion Research Facility; low/medium energy nuclear physics; high energy experimental physics; the Unisor program; experimental atomic physics; laser and electro-optics lab; theoretical physics; compilations and evaluations; and radioactive ion beam development. (LSP)
Pyrolysis oil combustion in a horizontal box furnace with an externally mixed nozzle

USDA-ARS?s Scientific Manuscript database

Combustion characteristics of neat biomass fast-pyrolysis oil were studied in a horizontal combustion chamber with a rectangular cross-section. An air-assisted externally mixed nozzle known to successfully atomize heavy fuel oils was installed in a modified nominal 100 kW (350,000 BTU/h nominal cap...
SOLAR OPACITY CALCULATIONS USING THE SUPER-TRANSITION-ARRAY METHOD

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

Krief, M.; Feigel, A.; Gazit, D., E-mail: menahem.krief@mail.huji.ac.il

A new opacity model has been developed based on the Super-Transition-Array (STA) method for the calculation of monochromatic opacities of plasmas in local thermodynamic equilibrium. The atomic code, named STAR (STA-Revised), is described and used to calculate spectral opacities for a solar model implementing the recent AGSS09 composition. Calculations are carried out throughout the solar radiative zone. The relative contributions of different chemical elements and atomic processes to the total Rosseland mean opacity are analyzed in detail. Monochromatic opacities and charge-state distributions are compared with the widely used Opacity Project (OP) code, for several elements near the radiation–convection interface. STARmore » Rosseland opacities for the solar mixture show a very good agreement with OP and the OPAL opacity code throughout the radiation zone. Finally, an explicit STA calculation was performed of the full AGSS09 photospheric mixture, including all heavy metals. It was shown that, due to their extremely low abundance, and despite being very good photon absorbers, the heavy elements do not affect the Rosseland opacity.« less
DOE Office of Scientific and Technical Information (OSTI.GOV)

Carvalho, R. S.; Ávila, H. C.; Cremona, M., E-mail: cremona@fis.puc-rio.br

The recently discovered organic magnetoresistance effect (OMAR) reveals the spin-dependent behavior of the charge transport in organic semiconductors. So far, it is known that hyperfine interactions play an important role in this phenomenon and also that spin-orbit coupling is negligible for light-atom based compounds. However, in the presence of heavy atoms, spin-orbit interactions should play an important role in OMAR. It is known that these interactions are responsible for singlet and triplet states mixing via intersystem crossing and the change of spin-charge relaxation time in the charge mobility process. In this work, we report a dramatic change in the OMARmore » effect caused by the presence of strong intramolecular spin-orbit coupling in a series of rare-earth quinolate organic complex-based devices. Our data show a different OMAR lineshape compared with the OMAR lineshape of tris(8-hydroxyquinolinate) aluminum-based devices, which are well described in the literature. In addition, electronic structure calculations based on density functional theory help to establish the connection between this results and the presence of heavy central ions in the different complexes.« less
Relativistic equation-of-motion coupled-cluster method using open-shell reference wavefunction: Application to ionization potential

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

Pathak, Himadri, E-mail: hmdrpthk@gmail.com; Sasmal, Sudip, E-mail: sudipsasmal.chem@gmail.com; Vaval, Nayana

2016-08-21

The open-shell reference relativistic equation-of-motion coupled-cluster method within its four-component description is successfully implemented with the consideration of single- and double- excitation approximations using the Dirac-Coulomb Hamiltonian. At the first attempt, the implemented method is employed to calculate ionization potential value of heavy atomic (Ag, Cs, Au, Fr, and Lr) and molecular (HgH and PbF) systems, where the effect of relativity does really matter to obtain highly accurate results. Not only the relativistic effect but also the effect of electron correlation is crucial in these heavy atomic and molecular systems. To justify the fact, we have taken two further approximationsmore » in the four-component relativistic equation-of-motion framework to quantify how the effect of electron correlation plays a role in the calculated values at different levels of theory. All these calculated results are compared with the available experimental data as well as with other theoretically calculated values to judge the extent of accuracy obtained in our calculations.« less
Purification, crystallization and X-ray diffraction analysis of the C-terminal protease domain of Venezuelan equine encephalitis virus nsP2

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

Russo, Andrew T.; Watowich, Stanley J., E-mail: watowich@xray.utmb.edu

2006-06-01

The C-terminal protease domain of Venezuelan equine encephalitis virus (VEEV) nsP2 has been overexpressed in E. coli, purified and successfully crystallized. Native crystals diffract to beyond 2.5 Å resolution and isomorphous heavy-atom derivatives suitable for phase analysis have been identified. The C-terminal region of Venezuelan equine encephalitis virus (VEEV) nsP2 is responsible for proteolytic processing of the VEEV polyprotein replication complex. This action regulates the activity of the replication complex and is essential for viral replication, thus making nsP2 a very attractive target for development of VEEV therapeutics. The 338-amino-acid C-terminal region of VEEV nsP2 has been overexpressed in Escherichiamore » coli, purified and crystallized. Crystals diffract to beyond 2.5 Å resolution and belong to the orthorhombic space group P2{sub 1}2{sub 1}2{sub 1}. Isomorphous heavy-atom derivatives suitable for phase analysis have been obtained and work on building a complete structural model is under way.« less
Swift heavy ion irradiation studies of GdFeO3 orthoferrite thin films

NASA Astrophysics Data System (ADS)

Kaur, Pawanpreet; Pandit, Rabia; Sharma, K. K.; Kumar, Ravi

2018-04-01

Thin films of GdFeO3, orthoferrite have been grown on MgO (001) substrate by pulsed laser deposition technique (PLD) to investigate the effect of swift heavy ion irradiation on their structural and magnetic properties. Thin films were irradiated with 200 MeV Ag15+ ions with fluence of 1×1011ions/cm2. The results of X-ray diffraction, atomic force microscopy and vibrating sample magnetometer characterization techniques are found to be different for the irradiated film from that of the pristine sample. The modifications in the irradiated samples are explained in terms of the ion-induced disorder.
HEAVY ION LINEAR ACCELERATOR

DOEpatents

Van Atta, C.M.; Beringer, R.; Smith, L.

1959-01-01

A linear accelerator of heavy ions is described. The basic contributions of the invention consist of a method and apparatus for obtaining high energy particles of an element with an increased charge-to-mass ratio. The method comprises the steps of ionizing the atoms of an element, accelerating the resultant ions to an energy substantially equal to one Mev per nucleon, stripping orbital electrons from the accelerated ions by passing the ions through a curtain of elemental vapor disposed transversely of the path of the ions to provide a second charge-to-mass ratio, and finally accelerating the resultant stripped ions to a final energy of at least ten Mev per nucleon.
Determination of allergen specificity by heavy chains in grass pollen allergen-specific IgE antibodies.

PubMed

Gadermaier, Elisabeth; Flicker, Sabine; Lupinek, Christian; Steinberger, Peter; Valenta, Rudolf

2013-04-01

Affinity and clonality of allergen-specific IgE antibodies are important determinants for the magnitude of IgE-mediated allergic inflammation. We sought to analyze the contribution of heavy and light chains of human allergen-specific IgE antibodies for allergen specificity and to test whether promiscuous pairing of heavy and light chains with different allergen specificity allows binding and might affect affinity. Ten IgE Fabs specific for 3 non-cross-reactive major timothy grass pollen allergens (Phl p 1, Phl p 2, and Phl p 5) obtained by means of combinatorial cloning from patients with grass pollen allergy were used to construct stable recombinant single chain variable fragments (ScFvs) representing the original Fabs and shuffled ScFvs in which heavy chains were recombined with light chains from IgE Fabs with specificity for other allergens by using the pCANTAB 5 E expression system. Possible ancestor genes for the heavy chain and light chain variable region-encoding genes were determined by using sequence comparison with the ImMunoGeneTics database, and their chromosomal locations were determined. Recombinant ScFvs were tested for allergen specificity and epitope recognition by means of direct and sandwich ELISA, and affinity by using surface plasmon resonance experiments. The shuffling experiments demonstrate that promiscuous pairing of heavy and light chains is possible and maintains allergen specificity, which is mainly determined by the heavy chains. ScFvs consisting of different heavy and light chains exhibited different affinities and even epitope specificity for the corresponding allergen. Our results indicate that allergen specificity of allergen-specific IgE is mainly determined by the heavy chains. Different heavy and light chain pairings in allergen-specific IgE antibodies affect affinity and epitope specificity and thus might influence clinical reactivity to allergens. Copyright © 2012 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.
Some heavy metals in Luciobarbus esocinus for public consumption and consumer protection.

PubMed

Düşükcan, M; Canpolat, Ö; Eroğlu, M

2017-09-30

In this study, the concentrations of some heavy metals were determined in the muscle of Luciobarbus esocinus Heckel, 1843 and in water where they live. The results were evaluated in term of potential human risk of consumption of this fish and the relationship between the heavy metal load of fish and some of their biological aspects (weight, length and sex). In addition, the accumulation factor of heavy metals in the muscle of L. esocinus were also determined. The Cr, Pb and Ni were not found in detectable levels according to results obtained by ICP. Only Cu, Zn and Fe were detected. It was found that heavy metals concentrations in the muscle of L. esocinus were higher than that in the water. The concentration of heavy metals showed differences according to weight, length and sex of fish. The results were discussed and compared with tolerable values for heavy metals provided from the EPA, FAO and WHO in order to determine whether this fish species has any risk for human consumption.
Sub-barrier quasifission in heavy element formation reactions with deformed actinide target nuclei

NASA Astrophysics Data System (ADS)

Hinde, D. J.; Jeung, D. Y.; Prasad, E.; Wakhle, A.; Dasgupta, M.; Evers, M.; Luong, D. H.; du Rietz, R.; Simenel, C.; Simpson, E. C.; Williams, E.

2018-02-01

Background: The formation of superheavy elements (SHEs) by fusion of two massive nuclei is severely inhibited by the competing quasifission process. Low excitation energies favor SHE survival against fusion-fission competition. In "cold" fusion with spherical target nuclei near 208Pb, SHE yields are largest at beam energies significantly below the average capture barrier. In "hot" fusion with statically deformed actinide nuclei, this is not the case. Here the elongated deformation-aligned configurations in sub-barrier capture reactions inhibits fusion (formation of a compact compound nucleus), instead favoring rapid reseparation through quasifission. Purpose: To determine the probabilities of fast and slow quasifission in reactions with prolate statically deformed actinide nuclei, through measurement and quantitative analysis of the dependence of quasifission characteristics at beam energies spanning the average capture barrier energy. Methods: The Australian National University Heavy Ion Accelerator Facility and CUBE fission spectrometer have been used to measure fission and quasifission mass and angle distributions for reactions with projectiles from C to S, bombarding Th and U target nuclei. Results: Mass-asymmetric quasifission occurring on a fast time scale, associated with collisions with the tips of the prolate actinide nuclei, shows a rapid increase in probability with increasing projectile charge, the transition being centered around projectile atomic number ZP=14 . For mass-symmetric fission events, deviations of angular anisotropies from expectations for fusion fission, indicating a component of slower quasifission, suggest a similar transition, but centered around ZP˜8 . Conclusions: Collisions with the tips of statically deformed prolate actinide nuclei show evidence for two distinct quasifission processes of different time scales. Their probabilities both increase rapidly with the projectile charge. The probability of fusion can be severely suppressed by these two quasifission processes, since the sub-barrier heavy element yield is likely to be determined by the product of the probabilities of surviving each quasifission process.
Universal many-body response of heavy impurities coupled to a Fermi sea: a review of recent progress

NASA Astrophysics Data System (ADS)

Schmidt, Richard; Knap, Michael; Ivanov, Dmitri A.; You, Jhih-Shih; Cetina, Marko; Demler, Eugene

2018-02-01

In this report we discuss the dynamical response of heavy quantum impurities immersed in a Fermi gas at zero and at finite temperature. Studying both the frequency and the time domain allows one to identify interaction regimes that are characterized by distinct many-body dynamics. From this theoretical study a picture emerges in which impurity dynamics is universal on essentially all time scales, and where the high-frequency few-body response is related to the long-time dynamics of the Anderson orthogonality catastrophe by Tan relations. Our theoretical description relies on different and complementary approaches: functional determinants give an exact numerical solution for time- and frequency-resolved responses, bosonization provides accurate analytical expressions at low temperatures, and the theory of Toeplitz determinants allows one to analytically predict response up to high temperatures. Using these approaches we predict the thermal decoherence rate of the fermionic system and prove that within the considered model the fastest rate of long-time decoherence is given by γ=π k_BT/4 . We show that Feshbach resonances in cold atomic systems give access to new interaction regimes where quantum effects can prevail even in the thermal regime of many-body dynamics. The key signature of this phenomenon is a crossover between different exponential decay rates of the real-time Ramsey signal. It is shown that the physics of the orthogonality catastrophe is experimentally observable up to temperatures T/T_F≲ 0.2 where it leaves its fingerprint in a power-law temperature dependence of thermal spectral weight and we review how this phenomenon is related to the physics of heavy ions in liquid {\\hspace{0pt}}3 He and the formation of Fermi polarons. The presented results are in excellent agreement with recent experiments on LiK mixtures, and we predict several new phenomena that can be tested using currently available experimental technology.
Sequential extraction of metals from mixed and digested sludge from aerobic WWTPs sited in the south of Spain

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

Alonso, E.; Aparicio, I.; Santos, J.L.

2009-01-15

The content of heavy metals is the major limitation to the application of sewage sludge in soil. However, assessment of the pollution by total metal determination does not reveal the true environmental impact. It is necessary to apply sequential extraction techniques to obtain suitable information about their bioavailability or toxicity. In this paper, sequential extraction of metals from sludge before and after aerobic digestion was applied to sludge from five WWTPs in southern Spain to obtain information about the influence of the digestion treatment in the concentration of the metals. The percentage of each metal as residual, oxidizable, reducible andmore » exchangeable form was calculated. For this purpose, sludge samples were collected from two different points of the plants, namely, sludge from the mixture (primary and secondary sludge) tank (mixed sludge, MS) and the digested-dewatered sludge (final sludge, FS). Heavy metals, Al, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Ti and Zn, were extracted following the sequential extraction scheme proposed by the Standards, Measurements and Testing Programme of the European Commission and determined by inductively-coupled plasma atomic emission spectrometry. The total concentration of heavy metals in the measured sludge samples did not exceed the limits set out by European legislation and were mainly associated with the two less-available fractions (27-28% as oxidizable metal and 44-50% as residual metal). However, metals as Co (64% in MS and 52% in FS samples), Mn (82% in MS and 79% in FS), Ni (32% in MS and 26% in FS) and Zn (79% in MS and 62% in FS) were present at important percentages as available forms. In addition, results showed a clear increase of the concentration of metals after sludge treatment in the proportion of two less-available fractions (oxidizable and residual metal)« less
Sequential extraction of metals from mixed and digested sludge from aerobic WWTPs sited in the south of Spain.

PubMed

Alonso, E; Aparicio, I; Santos, J L; Villar, P; Santos, A

2009-01-01

The content of heavy metals is the major limitation to the application of sewage sludge in soil. However, assessment of the pollution by total metal determination does not reveal the true environmental impact. It is necessary to apply sequential extraction techniques to obtain suitable information about their bioavailability or toxicity. In this paper, sequential extraction of metals from sludge before and after aerobic digestion was applied to sludge from five WWTPs in southern Spain to obtain information about the influence of the digestion treatment in the concentration of the metals. The percentage of each metal as residual, oxidizable, reducible and exchangeable form was calculated. For this purpose, sludge samples were collected from two different points of the plants, namely, sludge from the mixture (primary and secondary sludge) tank (mixed sludge, MS) and the digested-dewatered sludge (final sludge, FS). Heavy metals, Al, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Ti and Zn, were extracted following the sequential extraction scheme proposed by the Standards, Measurements and Testing Programme of the European Commission and determined by inductively-coupled plasma atomic emission spectrometry. The total concentration of heavy metals in the measured sludge samples did not exceed the limits set out by European legislation and were mainly associated with the two less-available fractions (27-28% as oxidizable metal and 44-50% as residual metal). However, metals as Co (64% in MS and 52% in FS samples), Mn (82% in MS and 79% in FS), Ni (32% in MS and 26% in FS) and Zn (79% in MS and 62% in FS) were present at important percentages as available forms. In addition, results showed a clear increase of the concentration of metals after sludge treatment in the proportion of two less-available fractions (oxidizable and residual metal).

Electronic Structure of Actinides under Pressure

NASA Astrophysics Data System (ADS)

Johansson, Borje

2006-03-01

The series of heavy radioactive elements known as the actinides all have similar elemental properties. However, when the volume per atom in the condensed phase is illustrated as a function of atomic number, perhaps the most dramatic anomaly in the periodic table becomes apparent. The atomic volume of americium is almost 50% larger than it is for the preceding element plutonium. For the element after americium, curium, the atomic volume is very close to that of americium. The same holds also for the next elements berkelium and californium. Accordingly from americium and onwards the actinides behave very similar to the corresponding rare-earth elements - a second lanthanide series of metallic elements can be identified. This view is strongly supported by the fact that all these elements adopt the dhcp structure, a structure typical for the lanthanides. The reason for this behavior is found in the behavior of the 5f electrons. For the earlier actinides, up to and including plutonium, the 5f electrons form metallic states and contribute most significantly to the bonding. In Np and Pu they even dominate the bonding, while all of a sudden they become localized in Am, very much like the 4f electrons in the lanthanide series, and contribute no longer to the cohesion. This withdrawal of 5f bonding gives rise to the large volume expansion between plutonium and americium. This difference between the light and heavy actinide suggests that it would be most worthwhile to strongly compress the transplutonium elements, thereby forcing the individual 5f electron wave functions into strong contact with each other (overlap). Recently high pressure experiments have been performed for americium and curium and dramatic crystal structure changes have been observed. These results and other high pressure data will be discussed in relation to the basic electronic structure of these elements.
An exacting transition probability measurement - a direct test of atomic many-body theories.

PubMed

Dutta, Tarun; De Munshi, Debashis; Yum, Dahyun; Rebhi, Riadh; Mukherjee, Manas

2016-07-19

A new protocol for measuring the branching fraction of hydrogenic atoms with only statistically limited uncertainty is proposed and demonstrated for the decay of the P3/2 level of the barium ion, with precision below 0.5%. Heavy hydrogenic atoms like the barium ion are test beds for fundamental physics such as atomic parity violation and they also hold the key to understanding nucleo-synthesis in stars. To draw definitive conclusion about possible physics beyond the standard model by measuring atomic parity violation in the barium ion it is necessary to measure the dipole transition probabilities of low-lying excited states with a precision better than 1%. Furthermore, enhancing our understanding of the barium puzzle in barium stars requires branching fraction data for proper modelling of nucleo-synthesis. Our measurements are the first to provide a direct test of quantum many-body calculations on the barium ion with a precision below one percent and more importantly with no known systematic uncertainties. The unique measurement protocol proposed here can be easily extended to any decay with more than two channels and hence paves the way for measuring the branching fractions of other hydrogenic atoms with no significant systematic uncertainties.
First survey of atmospheric heavy metal deposition in Kosovo using moss biomonitoring.

PubMed

Maxhuni, Albert; Lazo, Pranvera; Kane, Sonila; Qarri, Flora; Marku, Elda; Harmens, Harry

2016-01-01

Bryophytes act as bioindicators and bioaccumulators of metal deposition in the environment. The atmospheric deposition of Cd, Cr, Cu, Fe, Hg, Ni, Mn, Pb, and Zn in Kosovo was investigated by using carpet-forming moss species (Pseudocleropodium purum and Hypnum cupressiforme) as bioindicators. This research is part of the European moss survey coordinated by the ICP Vegetation, an International Cooperative Programme reporting on the effects of air pollution on vegetation to the UNECE Convention on Long-range Transboundary Air Pollution. Sampling was performed during the summer of 2011 at 25 sampling sites homogenously distributed over Kosovo. Unwashed, dried samples were digested by using wet digestion in Teflon tubes. The concentrations of metal elements were determined by atomic absorption spectrometry (AAS) equipped with flame and/or furnace systems. The heavy metal concentration in mosses reflected local emission sources. The data obtained in this study were compared with those of similar studies in neighboring countries and Europe (2010-2014 survey). The geographical distribution maps of the elements over the sampled territory were constructed using geographic information system (GIS) technology. The concentrations of Cr, Ni, Pb, and Zn were higher than the respective median values of Europe, suggesting that the zones with heavy vehicular traffic and industry emission input are important emitters of these elements. Selected zones are highly polluted particularly by Cd, Pb, Hg, and Ni. The statistical analyses revealed that a strong correlation exists between the Pb and Cd content in mosses, and the degree of pollution in the studied sites was assessed.
Placental concentrations of heavy metals in a mother-child cohort

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

Amaya, E., E-mail: eamayag@ugr.es; Gil, F.; Freire, C.

Heavy metals are environmental contaminants with properties known to be toxic for wildlife and humans. Despite strong concerns about their harmful effects, little information is available on intrauterine exposure in humans. The aim of this study was to evaluate prenatal exposure to As, Cd, Cr, Hg, Mn, and Pb and its association with maternal factors in a population-based mother-child cohort in Southern Spain. Between 2000 and 2002, 700 pregnant women were recruited and 137 placentas from the cohort were randomly selected and analyzed for the selected metals by atomic absorption. Maternal sociodemographic and lifestyle factors were obtained by questionnaire aftermore » delivery. Bivariate analysis and multivariate linear regression were performed. Cd and Mn concentrations were detected in all placentas, while Cr, Pb, and Hg were found in 98.5%, 35.0%, and 30.7% of samples, respectively. The highest concentrations were observed for Pb (mean: 94.80 ng/g wet weight of placenta), followed by Mn (63.80 ng/g), Cr (63.70 ng/g), Cd (3.45 ng/g), and Hg (0.024 ng/g). Arsenic was not detected in any sample. Gestational age and smoking during pregnancy were associated with placental Cd concentrations, while no factor appeared to influence concentrations of Cr, Hg, Mn, or Pb. In comparison to results of European studies, these concentrations are in a low-intermediate position. Studies are required to investigate the factors contributing to early exposure to heavy metals and to determine how placental transfer of these toxic compounds may affect children's health.« less
Radio-toxicity of spent fuel of the advanced heavy water reactor.

PubMed

Anand, S; Singh, K D S; Sharma, V K

2010-01-01

The Advanced Heavy Water Reactor (AHWR) is a new power reactor concept being developed at Bhabha Atomic Research Centre, Mumbai. The reactor retains many desirable features of the existing Pressurised Heavy Water Reactor (PHWR), while incorporating new, advanced safety features. The reactor aims to utilise the vast thorium resources available in India. The reactor core will use plutonium as the make-up fuel, while breeding (233)U in situ. On account of this unique combination of fuel materials, the operational characteristics of the fuel as determined by its radioactivity, decay heat and radio-toxicity are being viewed with great interest. Radio-toxicity of the spent fuel is a measure of potential radiological hazard to the members of the public and also important from the ecological point of view. The radio-toxicity of the AHWR fuel is extremely high to start with, being approximately 10(4) times that of the fresh natural U fuel used in a PHWR, and continues to remain relatively high during operation and subsequent cooling. A unique feature of this fuel is the peak observed in its radio-toxicity at approximately 10(5) y of decay cooling. The delayed increase in fuel toxicity has been traced primarily to a build-up of (229)Th, (230)Th and (226)Ra. This phenomenon has been observed earlier for thorium-based fuels and is confirmed for the AHWR fuel. This paper presents radio-toxicity data for AHWR spent fuel up to a period of 10(6) y and the results are compared with the radio-toxicity of PHWR.
Dielectronic recombination experiments at the storage rings: From the present CSR to the future HIAF

NASA Astrophysics Data System (ADS)

Huang, Z. K.; Wen, W. Q.; Xu, X.; Wang, H. B.; Dou, L. J.; Chuai, X. Y.; Zhu, X. L.; Zhao, D. M.; Li, J.; Ma, X. M.; Mao, L. J.; Yang, J. C.; Yuan, Y. J.; Xu, W. Q.; Xie, L. Y.; Xu, T. H.; Yao, K.; Dong, C. Z.; Zhu, L. F.; Ma, X.

2017-10-01

Dielectronic recombination (DR) experiments of highly charged ions at the storage rings have been developed as a precision spectroscopic tool to investigate the atomic structure as well as nuclear properties of stable and unstable nuclei. The DR experiment on lithium-like argon ions was successfully performed at main Cooler Storage Ring (CSRm) at Heavy Ion Research Facility in Lanzhou (HIRFL) accelerator complex. The DR experiments on heavy highly charged ions and even radioactive ions are currently under preparation at the experimental Cooler Storage Ring (CSRe) at HIRFL. The current status of DR experiments at the CSRm and the preparation of the DR experiments at the CSRe are presented. In addition, an overview of DR experiments by employing an electron cooler and a separated ultra-cold electron target at the upcoming High Intensity heavy ion Accelerator Facility (HIAF) will be given.
Experimental survey of the production of α -decaying heavy elements in 238U+232Th reactions at 7.5-6.1 MeV/nucleon

NASA Astrophysics Data System (ADS)

Wuenschel, S.; Hagel, K.; Barbui, M.; Gauthier, J.; Cao, X. G.; Wada, R.; Kim, E. J.; Majka, Z.; Płaneta, R.; Sosin, Z.; Wieloch, A.; Zelga, K.; Kowalski, S.; Schmidt, K.; Ma, C.; Zhang, G.; Natowitz, J. B.

2018-06-01

The production of α -particle decaying heavy nuclei in reactions of 7.5-6.1 MeV/nucleon 238U +232Th was explored using an in-beam detection array composed of YAP scintillators and gas ionization chamber-Si telescopes. Comparisons of α energies and half-lives for the observed products with those of the previously known isotopes and with theoretically predicted values indicate the observation of a number of previously unreported α emitters. α -particle decay energies reaching as high as 12 MeV are observed. Many of these are expected to be from decay of previously unseen relatively neutron rich products. While the contributions of isomeric states require further exploration and specific isotope identifications need to be made, the production of heavy isotopes with quite high atomic numbers is suggested by the data.
FROM THE HISTORY OF PHYSICS: The development of the first Soviet atomic bomb

NASA Astrophysics Data System (ADS)

Goncharov, German A.; Ryabev, Lev D.

2001-01-01

In the late 1930s and early 1940s, two remarkable physical phenomena — the fission of heavy nuclei and the chain fission reaction — were discovered, implying that a new powerful source of energy (nuclear fission energy) might become a practical possibility for mankind. At that time, however, the political situation in the world made the development of the atomic bomb the main objective of nuclear energy research in the countries involved. The first atomic bombs, notoriously used in the war against Japan, were produced by the United States of America only six and a half years after the discovery of fission. Four years later, the first Soviet atomic bomb was tested. This was a major step toward the establishment of nuclear parity which led to stability and global peace and thus greatly influenced the destiny of human kind. Based on documentary materials covering the period from 1939 to 1949, this paper traces the origin and evolution of the physical ideas behind the first Soviet atomic bomb and discusses the most important events associated with the project.
Determination of the line shapes of atomic nitrogen resonance lines by magnetic scans

NASA Technical Reports Server (NTRS)

Lawrence, G. M.; Stone, E. J.; Kley, D.

1976-01-01

A technique is given for calibrating an atomic nitrogen resonance lamp for use in determining column densities of atoms in specific states. A discharge lamp emitting the NI multiplets at 1200 A and 1493 A is studied by obtaining absorption by atoms in a magnetic field (0-2.5 T). This magnetic scanning technique enables the determination of the absorbing atom column density, and an empirical curve of growth is obtained because the atomic f-value is known. Thus, the calibrated lamp can be used in the determination of atomic column densities.
Kinetics of color center formation in silica irradiated with swift heavy ions: Thresholding and formation efficiency

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

Manzano-Santamaria, J.; Euratom/CIEMAT Fusion Association, Madrid; Olivares, J.

2012-10-08

We have determined the cross-section {sigma} for color center generation under single Br ion impacts on amorphous SiO{sub 2}. The evolution of the cross-sections, {sigma}(E) and {sigma}(S{sub e}), show an initial flat stage that we associate to atomic collision mechanisms. Above a certain threshold value (S{sub e} > 2 keV/nm), roughly coinciding with that reported for the onset of macroscopic disorder (compaction), {sigma} shows a marked increase due to electronic processes. In this regime, a energetic cost of around 7.5 keV is necessary to create a non bridging oxygen hole center-E Prime (NBOHC/E Prime ) pair, whatever the input energy.more » The data appear consistent with a non-radiative decay of self-trapped excitons.« less
[Effect of cigarette smoking on coexistence of cadmium and zinc in retained wisdom teeth].

PubMed

Malara, Piotr; Kwapuliński, Jerzy; Drugacz, Jan; Malara, Beata

2005-01-01

The change in coexistence pattern of elements (antagonism-synergism) in conditions of excessive level of toxic element is observed in many biological samples. The aim of this study was to establish the cadmium and zinc content in hard tissues of retained wisdom teeth of smokers and non-smokers and to find out if active exposure to cigarette smoke has an influence on coexistence of both metals in these tissues. Material consisted of 127 retained wisdom teeth (65 from smokers and 62 from non-smokers). Cadmium and zinc contents were determined by means of atomic absorption spectrometry. We found out that retained wisdom tooth from smokers exhibited higher cadmium and zinc contents compared to non-smokers' teeth. Moreover, coexistence pattern of cadmium and zinc in teeth depends on exposure to heavy metals and exhibits strong synergism in smokers.
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 study of effective atomic numbers and electron densities of some vitamins for electron, H, He and C ion interactions

NASA Astrophysics Data System (ADS)

Büyükyıldız, M.

2017-09-01

The radiological properties of some vitamins such as Retinol, Beta-carotene, Riboflavin, Niacin, Niacinamide, Pantothenic acid, Pyridoxine, Pyridoxamine, Pyridoxal, Biotin, Folic acid, Ascorbic acid, Cholecalciferol, Alpha-tocopherol, Gamma-tocopherol, Phylloquinone have been investigated with respect to total electron interaction and some heavy charged particle interaction as means of effective atomic numbers (Z_{eff}) and electron densities (N_{eff}) for the first time. Calculations were performed for total electron interaction and heavy ions such as H, He and C ion interactions in the energy region 10keV-10MeV by using a logarithmic interpolation method. Variations in Z_{eff}'s and N_{eff}'s of given vitamins have been studied according to the energy of electron or heavy charged particles, and significant variations have been observed for all types of interaction in the given energy region. The maximum values of Z_{eff} have been found in the different energy regions for different interactions remarkably and variations in N_{eff} seem approximately to be the same with variation in Z_{eff} for the given vitamins as expected. Z_{eff} values of some vitamins were plotted together and compared with each other for electron, H, He and C interactions and the ratios of Z_{eff}/ < A > have been changed in the range of 0.25-0.36, 0.20-0.36, 0.22-0.35 and 0.20-0.35 for electron, H, He and C interactions, respectively.
Polarized negative ions

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

Haeberli, W.

1981-04-01

This paper presents a survey of methods, commonly in use or under development, to produce beams of polarized negative ions for injection into accelerators. A short summary recalls how the hyperfine interaction is used to obtain nuclear polarization in beams of atoms. Atomic-beam sources for light ions are discussed. If the best presently known techniques are incorporated in all stages of the source, polarized H/sup -/ and D/sup -/ beams in excess of 10 ..mu..A can probably be achieved. Production of polarized ions from fast (keV) beams of polarized atoms is treated separately for atoms in the H(25) excited statemore » (Lamb-Shift source) and atoms in the H(1S) ground state. The negative ion beam from Lamb-Shift sources has reached a plateau just above 1 ..mu..A, but this beam current is adequate for many applications and the somewhat lower beam current is compensated by other desirable characteristics. Sources using fast polarized ground state atoms are in a stage of intense development. The next sections summarize production of polarized heavy ions by the atomic beam method, which is well established, and by optical pumping, which has recently been demonstrated to yield very large nuclear polarization. A short discussion of proposed ion sources for polarized /sup 3/He/sup -/ ions is followed by some concluding remarks.« less
40 CFR 86.1104-91 - Determination of upper limits.

Code of Federal Regulations, 2010 CFR

2010-07-01

...) Nonconformance Penalties for Gasoline-Fueled and Diesel Heavy-Duty Engines and Heavy-Duty Vehicles, Including... pollutant emission standard for a subclass of heavy-duty engines or heavy-duty vehicles for which an NCP is...
Speciation and distribution of cadmium and lead in salinized horizons of antrosols

NASA Astrophysics Data System (ADS)

Bulgariu, D.; Bulgariu, L.; Astefanei, D.

2009-04-01

The utilization of intensive technologies for the vegetable cultivation in glass houses by the administration of high doses of organic fertilizes, the supra-dimensional irrigation and the maintaining of soil at high humidity state, in special in case of vicious drainage have as result the rapid degradation of morphological, chemical and physical characteristics of soils, concretized by: (i) decrease of structural aggregates stability; (ii) more dense packing of soil; (iii) accumulation of easy soluble salts (in special at superior horizons level); (iv) limitation of organic compounds and micro-elements biodisponibility. All these determined a significant reduction of productivity and of exploitation duration of soils from glass houses. These phenomena modified continuously the dynamic of speciation processes and inter-phases distribution, of heavy metals in soils from glass houses, and can determined a non-controlled accumulation of heavy metals, in special as mobile forms with high biodisponibility. Ours studied have been performed using soil profiles drawing from Copou-glass house, Iasi (Romania). Has been followed the modification of distribution for speciation forms of cadmium and lead (two heavy metals with high toxicity degree), between hortic antrosol horizons, and between chemical-mineralogical components of this, with the progressive salinization of superior horizons, in 2007-2008 period. The separation, differentiation and determination of cadmium and lead speciation forms was done by combined solid-liquid sequential extraction (SPE) and extraction in aqueous polymer-inorganic salt two-phase systems (ABS) procedure, presented in some of ours previous studies. After extraction, the total contents of the two heavy metals and fractions from these differential bonded by mineral and organic components of hortic antrosol have been determined by atomic absorption spectrometry. The specific interaction mechanisms of Cd and Pb with organic-mineral components of soils have been estimated on the basis of Raman and FT-IR spectra, recorded for fractions obtained after each extraction step. These data were correlated with those obtained by chemical analysis and UV-VIS spectrometry, and were used for to establish the type and weight of Cd and Pb speciation forms in studied antrosol. Our studies have been show that in medium and inferior horizons of hortic antrosols, the heavy metals have a general accumulation tendency, preferential by binding on organic matter and organic-mineral complexes, components with higher abundance in such type of soils. The selectivity and complexation mechanisms are controlled by speciation forms of the two metals. This phenomenon has two important consequences, the strong fixation of heavy metals in hortic antrosol and significant modification of structure and conformation of organic macromolecules. A specific phenomenon of hortic antrosols is that the accumulation rate of heavy metals is higher than levigation rate, and the mobile forms of these have a higher biodisponibility, being relative easy assimilated by plants. The progressive salinization of superior horizons of soils from glass houses, determined a sever perturbation of equilibrium between Cd and Pb speciation forms. In consequence these will have an accentuated migration tendency in superior horizons, as complexes with inorganic ligands, with a high mobility and biodsiponibility. The accumulation of soluble salts in superior horizons, and the formation of frangipane horizon (horizon of geochemical segregation of hortic antrosols) modified the ionic strength from soil solution and the thermodynamic activity of cadmium and lead species. Under these conditions, the levigation rate of cadmium and lead is higher than the accumulation rate, which means that the migration of these metals in soil solution occurs fast and in high concentrations. Acknowledgments The authors would like to acknowledge the financial support from Romanian Ministry of Education and Research (Project PNCDI 2-D5 no. 51045/07 an Project PNCDI 2-D5 no. 52141 / 08).
Determining oxygen relaxations at an interface: A comparative study between transmission electron microscopy techniques.

PubMed

Gauquelin, N; van den Bos, K H W; Béché, A; Krause, F F; Lobato, I; Lazar, S; Rosenauer, A; Van Aert, S; Verbeeck, J

2017-10-01

Nowadays, aberration corrected transmission electron microscopy (TEM) is a popular method to characterise nanomaterials at the atomic scale. Here, atomically resolved images of nanomaterials are acquired, where the contrast depends on the illumination, imaging and detector conditions of the microscope. Visualization of light elements is possible when using low angle annular dark field (LAADF) STEM, annular bright field (ABF) STEM, integrated differential phase contrast (iDPC) STEM, negative spherical aberration imaging (NCSI) and imaging STEM (ISTEM). In this work, images of a NdGaO 3 -La 0.67 Sr 0.33 MnO 3 (NGO-LSMO) interface are quantitatively evaluated by using statistical parameter estimation theory. For imaging light elements, all techniques are providing reliable results, while the techniques based on interference contrast, NCSI and ISTEM, are less robust in terms of accuracy for extracting heavy column locations. In term of precision, sample drift and scan distortions mainly limits the STEM based techniques as compared to NCSI. Post processing techniques can, however, partially compensate for this. In order to provide an outlook to the future, simulated images of NGO, in which the unavoidable presence of Poisson noise is taken into account, are used to determine the ultimate precision. In this future counting noise limited scenario, NCSI and ISTEM imaging will provide more precise values as compared to the other techniques, which can be related to the mechanisms behind the image recording. Copyright © 2017 Elsevier B.V. All rights reserved.
Investigation of radiological properties of some shielding materials on charged and uncharged radiation interaction for neutron generator

NASA Astrophysics Data System (ADS)

Büyükyıldız, Mehmet

2017-04-01

Radiation interaction parameters such as total stopping power, projected range (longitudinal and lateral) straggling, mass attenuation coefficient, effective atomic number (Zeff) and electron density (Neff) of some shielding materials were investigated for photon and heavy charged particle interactions. The ranges, stragglings and mass attenuation coefficients were calculated for the high-density polyethylene(HDPE), borated polyethylene (BPE), brick (common silica), concrete (regular), wood, water, stainless steel (304), aluminum (alloy 6061-O), lead and bismuth using SRIM Monte Carlo software and WinXCom program. In addition, effective atomic numbers (Zeff) and electron densities (Neff) of HDPE, BPE, brick (common silica), concrete (regular), wood, water, stainless steel (304) and aluminum (alloy 6061-O) were calculated in the energy region 10 keV-100 MeV using mass stopping powers and mass attenuation coefficients. Two different methods namely direct and interpolation procedures were used to calculate Zeff for comparison and significant differences were determined between the methods. Variations of the ranges, longitudinal and lateral stragglings of water, concrete and stainless steel (304) were compared with each other in the continuous kinetic energy region and discussed with respect to their Zeffs. Moreover, energy absorption buildup factors (EABF) and exposure buildup factors (EBF) of the materials were determined for gamma rays as well and were compared with each other for different photon energies and different mfps in the photon energy region 0.015-15 MeV.
Simulations as a tool for higher mass resolution spectrometer: Lessons from existing observations

NASA Astrophysics Data System (ADS)

Nicolaou, Georgios; Yamauchi, Masatoshi; Nilsson, Hans; Wieser, Martin; Fedorov, Andrei

2017-04-01

Scientific requirements of each mission are crucial for the instrument's design. Ion tracing simulations of instruments can be helpful to characterize their performance, identify their limitations and improving the design for future missions. However, simulations provide the best performance in ideal case, and the actual response is determined by many other factors. Therefore, simulations should be compared with observations when possible. Characterizing the actual response of a running instrument gives valuable lessons for the future design of test instruments with the same detection principle before spending resources to build and calibrate them. In this study we use an ion tracing simulation of the Ion Composition Analyser (ICA) on board ROSETTA, in order to characterize its response and to compare it with the observations. It turned out that, due to the complicated unexpected response of the running instrument, the heavy cometary ions and molecules are sometimes difficult to be resolved. However, preliminary simulation of a slightly modified design predicts much higher mass resolution. Even after considering the complicated unexpected response, we safely expect that the modified design can resolve most abundant heavy atomic ions (e.g., O^+) and molecular ions (e.g., N_2+ and O_2^+). We show the simulation results for both designs and ICA data.
A layered magnetic iron/iron oxide nanoscavenger for the analytical enrichment of ng-L(-1) concentration levels of heavy metals from water.

PubMed

Karatapanis, Andreas E; Petrakis, Dimitrios E; Stalikas, Constantine D

2012-05-13

Magnetically driven separation techniques have received considerable attention in recent decade because of their great potential application. In this study, we investigate the application of an unmodified layered magnetic Fe/Fe(2)O(3) nanoscavenger for the analytical enrichment and determination of sub-parts per billion concentrations of Cd(II), Pb(II), Ni(II), Cr(VI) and As(V) from water samples. The synthesized nanoscavenger was characterized by BET, TGA, XRD and IR and the parameters influencing the extraction and recovery of the preconcentration process were assessed by atomic absorption spectrometry. The possible mechanism of the enrichment of heavy metals on Fe/Fe(2)O(3) was proposed, which involved the dominant adsorption and reduction. The nanoscale size offers large surface area and high reactivity of sorption and reduction reactions. The obtained limits of detection for the metals studied were in the range of 20-125 ng L(-1) and the applicability of the nanomaterial was verified using a real sample matrix. The method is environmentally friendly as only 15 mg of nanoscavenger are used, no organic solvent is required for the extraction and the experiment is performed without the need for filtration or preparation of packed preconcentration columns. Copyright © 2012 Elsevier B.V. All rights reserved.

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