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Sample records for shell electronic structure

  1. Electronic shell structure and chemisorption on gold nanoparticles

    DEFF Research Database (Denmark)

    Larsen, Ask Hjorth; Kleis, Jesper; Thygesen, Kristian Sommer

    2011-01-01

    to distort considerably, creating large band gaps at the Fermi level. For up to 200 atoms we consider structures generated with a simple EMT potential and clusters based on cuboctahedra and icosahedra. All types of cluster geometry exhibit jelliumlike electronic shell structure. We calculate adsorption...... energies of several atoms on the cuboctahedral clusters. Adsorption energies are found to vary abruptly at magic numbers. Using a Newns-Anderson model we find that the effect of magic numbers on adsorption energy can be understood from the location of adsorbate-induced states with respect to the cluster...

  2. Electronic Structure of Single- and Multiple-shell Carbon Fullerenes

    OpenAIRE

    Lin, Yeong-Lieh; Nori, Franco

    1993-01-01

    We study the electronic states of giant single-shell and the recently discovered nested multi-shell carbon fullerenes within the tight-binding approximation. We use two different approaches, one based on iterations and the other on symmetry, to obtain the $\\pi$-state energy spectra of large fullerene cages: $C_{240}$, $C_{540}$, $C_{960}$, $C_{1500}$, $C_{2160}$ and $C_{2940}$. Our iteration technique reduces the dimensionality of the problem by more than one order of magnitude (factors of $\\...

  3. Electronic structure of single- and multiple-shell carbon fullerenes

    International Nuclear Information System (INIS)

    Lin, Y.; Nori, F.

    1994-01-01

    We study the electronic states of giant single-shell and the recently discovered nested multiple-shell carbon fullerenes within the tight-binding approximation. We use two different approaches, one based on iterations and the other on symmetry, to obtain the π-state energy spectra of large fullerene cages: C 240 , C 540 , C 960 , C 1500 , C 2160 , and C 2940 . Our iteration technique reduces the size of the problem by more than one order of magnitude (factors of ∼12 and 20), while the symmetry-based approach reduces it by a factor of 10. We also find formulas for the highest occupied and lowest unoccupied molecular orbital energies of C 60n 2 fullerenes as a function of n, demonstrating a tendency towards a metallic regime for increasing n. For multiple-shell fullerenes, we analytically obtain the eigenvalues of the intershell interaction

  4. Morphology and electronic structure of the oxide shell on the surface of iron nanoparticles.

    Science.gov (United States)

    Wang, Chongmin; Baer, Donald R; Amonette, James E; Engelhard, Mark H; Antony, Jiji; Qiang, You

    2009-07-01

    An iron (Fe) nanoparticle exposed to air at room temperature will be instantly covered by an oxide shell that is typically approximately 3 nm thick. The nature of this native oxide shell, in combination with the underlying Fe(0) core, determines the physical and chemical behavior of the core-shell nanoparticle. One of the challenges of characterizing core-shell nanoparticles is determining the structure of the oxide shell, that is, whether it is FeO, Fe(3)O(4), gamma-Fe(2)O(3), alpha-Fe(2)O(3), or something else. The results of prior characterization efforts, which have mostly used X-ray diffraction and spectroscopy, electron diffraction, and transmission electron microscopic imaging, have been framed in terms of one of the known Fe-oxide structures, although it is not necessarily true that the thin layer of Fe oxide is a known Fe oxide. In this Article, we probe the structure of the oxide shell on Fe nanoparticles using electron energy loss spectroscopy (EELS) at the oxygen (O) K-edge with a spatial resolution of several nanometers (i.e., less than that of an individual particle). We studied two types of representative particles: small particles that are fully oxidized (no Fe(0) core) and larger core-shell particles that possess an Fe core. We found that O K-edge spectra collected for the oxide shell in nanoparticles show distinct differences from those of known Fe oxides. Typically, the prepeak of the spectra collected on both the core-shell and the fully oxidized particles is weaker than that collected on standard Fe(3)O(4). Given the fact that the origin of this prepeak corresponds to the transition of the O 1s electron to the unoccupied state of O 2p hybridized with Fe 3d, a weak pre-edge peak indicates a combination of the following four factors: a higher degree of occupancy of the Fe 3d orbital; a longer Fe-O bond length; a decreased covalency of the Fe-O bond; and a measure of cation vacancies. These results suggest that the coordination configuration in

  5. Electronic shell structure in multiply charged silver clusters

    International Nuclear Information System (INIS)

    Kandler, O.; Athanassenas, K.; Echt, O.; Kreisle, D.; Leisner, T.; Recknagel, E.

    1991-01-01

    Silver clusters are generated by standard laser vaporization technique and ionized via multiphoton ionization. Time-of-flight mass spectrometry reveals singly, doubly and triply charged clusters, Ag n z+ (z=1, 2, 3). The spectra show, for all charge states, intensity variations, indicating enhanced stabilities for cluster sizes with closed electronic configurations in accord with the spherical jellium model. (orig.)

  6. Super-paramagnetic core-shell material with tunable magnetic behavior by regulating electron transfer efficiency and structure stability of the shell

    Directory of Open Access Journals (Sweden)

    Wenyan Zhang

    Full Text Available In this work, a spherical nano core-shell material was constructed by encapsulating Fe3O4 microsphere into conductive polymer-metal composite shell. The Fe3O4 microspheres were fabricated by assembling large amounts of Fe3O4 nano-crystals, which endowed the microspheres with super-paramagnetic property and high saturation magnetization. The polymer-metal composite shell was constructed by inserting Pt nano-particles (NPs into the conductive polymer polypyrrole (PPy. As size and dispersion of the Pt NPs has an important influence on their surface area and surface energy, it was effective to enlarge the interface area between PPy and Pt NPs, enhance the electron transfer efficiency of PPy/Pt composite shell, and reinforced the shell’s structural stability just by tuning the size and dispersion of Pt NPs. Moreover, core-shell structure of the materials made it convenient to investigate the PPy/Pt shell’s shielding effect on the Fe3O4 core’s magnetic response to external magnetic fields. It was found that the saturation magnetization of Fe3O4/PPy/Pt core-shell material could be reduced by 20.5% by regulating the conductivity of the PPy/Pt shell. Keywords: Super-paramagnetic, Conductivity, Magnetic shielding, Structural stability

  7. Electronic structure and intersubband magnetoabsorption spectra of CdSe/CdS core-shell nanowires

    Science.gov (United States)

    Xiong, Wen

    2016-10-01

    The electronic structures of CdSe/CdS core-shell nanowires are calculated based on the effective-mass theory, and it is found that the hole states in CdSe/CdS core-shell nanowires are strongly mixed, which are very different from the hole states in CdSe or CdS nanowires. In addition, we find the three highest hole states at the Γ point are almost localized in the CdSe core and the energies of the hole states in CdSe/CdS core-shell nanowires can be enhanced greatly when the core radius Rc increases and the total radius R is fixed. The degenerate hole states are split by the magnetic field, and the split energies will increase when |Jh | increases from 1/2 to 7/2, while they are almost not influenced by the change of the core radius Rc. The absorption spectra of CdSe/CdS core-shell nanowires at the Γ point are also studied in the magnetic field when the temperature T is considered, and we find there are only two peaks will arise if the core radius Rc and the temperature T increase. The intensity of each optical absorption can be considerably enhanced by increasing the core radius Rc when the temperature T is fixed, it is due to the increase of their optical transition matrix element. Meanwhile, the intensity of each optical absorption can be decreased when the temperature T increases and the core radius Rc is fixed, and this is because the Fermi-Dirac distribution function of the corresponding hole states will increase as the increase of the temperature T.

  8. Cu–Ni core–shell nanoparticles: structure, stability, electronic, and magnetic properties: a spin-polarized density functional study

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qiang, E-mail: wangqiang@njtech.edu.cn; Wang, Xinyan; Liu, Jianlan; Yang, Yanhui [Nanjing Tech University, School of Chemistry and Molecular Engineering, Institute of Advanced Synthesis (IAS) (China)

    2017-02-15

    Bimetallic core–shell nanoparticles (CSNPs) have attracted great interest not only because of their superior stability, selectivity, and catalytic activity but also due to their tunable properties achieved by changing the morphology, sequence, and sizes of both core and shell. In this study, the structure, stability, charge transfer, electronic, and magnetic properties of 13-atom and 55-atom Cu and Cu–Ni CSNPs were investigated using the density functional theory (DFT) calculations. The results show that Ni@Cu CSNPs with a Cu surface shell are more energetically favorable than Cu@Ni CSNPs with a Ni surface shell. Interestingly, three-shell Ni@Cu{sub 12}@Ni{sub 42} is more stable than two-shell Cu{sub 13}@Ni{sub 42}, while two-shell Ni{sub 13}@Cu{sub 42} is more stable than three-shell Cu@Ni{sub 12}@Cu{sub 42}. Analysis of Bader charge illustrates that the charge transfer increases from Cu core to Ni shell in Cu@Ni NPs, while it decreases from Ni core to Cu shell in Ni@Cu NPs. Furthermore, the charge transfer results that d-band states have larger shift toward the Fermi level for the Ni@Cu CSNPs with Cu surface shell, while the Cu@Ni CSNPs with Ni surface shell have similar d-band state curves and d-band centers with the monometallic Ni NPs. In addition, the Cu–Ni CSNPs possess higher magnetic moment when the Ni atoms aggregated at core region of CSNPs, while having lower magnetic moment when the Ni atoms segregate on surface region. The change of the Cu atom location in CSNPs has a weak effect on the total magnetic moment. Our findings provide useful insights for the design of bimetallic core–shell catalysts.

  9. Rotational and fine structure of open-shell molecules in nearly degenerate electronic states

    Science.gov (United States)

    Liu, Jinjun

    2018-03-01

    An effective Hamiltonian without symmetry restriction has been developed to model the rotational and fine structure of two nearly degenerate electronic states of an open-shell molecule. In addition to the rotational Hamiltonian for an asymmetric top, this spectroscopic model includes the energy separation between the two states due to difference potential and zero-point energy difference, as well as the spin-orbit (SO), Coriolis, and electron spin-molecular rotation (SR) interactions. Hamiltonian matrices are computed using orbitally and fully symmetrized case (a) and case (b) basis sets. Intensity formulae and selection rules for rotational transitions between a pair of nearly degenerate states and a nondegenerate state have also been derived using all four basis sets. It is demonstrated using real examples of free radicals that the fine structure of a single electronic state can be simulated with either a SR tensor or a combination of SO and Coriolis constants. The related molecular constants can be determined precisely only when all interacting levels are simulated simultaneously. The present study suggests that analysis of rotational and fine structure can provide quantitative insights into vibronic interactions and related effects.

  10. Shell-like structures

    CERN Document Server

    Altenbach, Holm

    2011-01-01

    In this volume, scientists and researchers from industry discuss the new trends in simulation and computing shell-like structures. The focus is put on the following problems: new theories (based on two-dimensional field equations but describing non-classical effects), new constitutive equations (for materials like sandwiches, foams, etc. and which can be combined with the two-dimensional shell equations), complex structures (folded, branching and/or self intersecting shell structures, etc.) and shell-like structures on different scales (for example: nano-tubes) or very thin structures (similar

  11. Strontium clusters: electronic and geometry shell effects

    DEFF Research Database (Denmark)

    Lyalin, Andrey G.; Solov'yov, Ilia; Solov'yov, Andrey V.

    2008-01-01

    charged strontium clusters consisting of up to 14 atoms, average bonding distances, electronic shell closures, binding energies per atom, and spectra of the density of electronic states (DOS). It is demonstrated that the size-evolution of structural and electronic properties of strontium clusters...... is governed by an interplay of the electronic and geometry shell closures. Influence of the electronic shell effects on structural rearrangements can lead to violation of the icosahedral growth motif of strontium clusters. It is shown that the excessive charge essentially affects the optimized geometry...

  12. Local conditions for the Pauli potential in order to yield self-consistent electron densities exhibiting proper atomic shell structure

    Energy Technology Data Exchange (ETDEWEB)

    Finzel, Kati, E-mail: kati.finzel@liu.se [Linköpings University, IFM Department of Physics, 58183 Linköping (Sweden)

    2016-01-21

    The local conditions for the Pauli potential that are necessary in order to yield self-consistent electron densities from orbital-free calculations are investigated for approximations that are expressed with the help of a local position variable. It is shown that those local conditions also apply when the Pauli potential is given in terms of the electron density. An explicit formula for the Ne atom is given, preserving the local conditions during the iterative procedure. The resulting orbital-free electron density exhibits proper shell structure behavior and is in close agreement with the Kohn-Sham electron density. This study demonstrates that it is possible to obtain self-consistent orbital-free electron densities with proper atomic shell structure from simple one-point approximations for the Pauli potential at local density level.

  13. Structures in the K-shell delta electron spectrum near threshold for ionization by fast charged particles

    International Nuclear Information System (INIS)

    Amundsen, P.A.; Aashamar, K.

    Results of calculations of the delta electron spectrum for K-shell ionization of atoms by fast charged particles for target charges in the range 6 2 <=40 are presented. Appreciable structure is found in the spectrum near the ionization threshold, in particular for fast projectiles and heavy target elements. The structure can be quite sensitive to the details of the effective atomic potentials. (Auth.)

  14. The Quasi-Electron Shell Structure of the Fractional Quantum Hall Effect

    Science.gov (United States)

    Haxton, Wick; Haxton, Daniel

    2015-04-01

    The fractional quantum Hall effect (FQHE) formulated on a sphere resembles the nuclear shell model, with the desired translationally invariant states having total angular momentum zero. This property was exploited by Ginocchio and Haxton (GH) to derive a new set of scalar operators and a first-Landau-level representation of the full set of hierarchy states (fillings 1/3, 2/5, 3/7, etc.), with overlaps identical to those of Jain, who used unphysical higher Landau levels excitations followed by numerical projection. We demonstrate that the GH operators produce an appealing description of the FQHE as shells filled by non-interacting quasi-electrons, or composite fermions. These are explicitly constructed, and their planar forms are also found. The evolution of the shells and their quasi-electrons is quite unusual. The connections with electron correlations and Laughlin's variational arguments are described. We discuss how ``new states'' found experimentally at fillings such as 4/11 and 5/13 fit into this scheme. Work support in part by the US DOE Offices of Nuclear Physics and Basic Energy Sciences.

  15. Triple layered core–shell structure with surface fluorinated ZnO-carbon nanotube composites and its electron emission properties

    International Nuclear Information System (INIS)

    Wang, H.Y.; Chua, Daniel H.C.

    2013-01-01

    Highlights: ► The effects of CF 4 plasma on ZnO-CNT core–shell structures were studied. ► ZnO was effective in protecting the aligned CNTs core for as long as 30 min of plasma etching. ► SEM showed the surface morphology was nearly similar between pristine, 2 min and 30 min plasma etched specimens. ► F was observed to displace O in ZnO. ► This is the first report of an ultra long plasma etch of fluorine onto ZnO surface. - Abstract: Core-shelled structures such as zinc oxide (ZnO) on carbon nanotubes (CNTs) give rise to interesting material properties. In this work, a triple-layered core–shell–shell structure is presented where the effects of fluorine (F) incorporation on the outmost shell of the ZnO-CNT structure are studied. The samples prepared ranged from a short 2 min to a 30 min immersion in carbon tetraflouride (CF 4 ) plasma. In addition, its effects on the electron emission properties also studied and it is shown that the plasma immersions create thinner field emitters with sharp tiny wrinkles giving rise to more electron emission sites and higher enhancement factor. In addition, X-ray photoelectron spectroscopy measurements showed that F ions replace O in ZnO coatings during immersion process, thus increasing the electrical conductivity and shifts the Fermi level of ZnO upwards. Both physical and electronic effects further contribute to a lower threshold field.

  16. Inner-shell electron spectroscopy for microanalysis

    International Nuclear Information System (INIS)

    Joy, D.C.; Maher, D.M.

    1979-01-01

    The transmission electron energy-loss spectrum shows characteristic edges corresponding to the excitation of inner-shell electrons of atoms in a thin sample. Analysis of these edges provides detailed chemical, structural, and electronic data from the radiated volume. By combining electron spectroscopy and electron microscopy, this microanalytical technique can be performed in conjunction with high-resolution imaging of the sample. It is shown that this approach has advantages of sensitivity, spatial resolution, and convenience over other comparable techniques. 7 figures

  17. Electronic structure of the 3d metals. An investigation by L-shell-photoionisation

    Energy Technology Data Exchange (ETDEWEB)

    Richter, T.S.

    2007-12-03

    The 3d transition metal elements from Sc to Cu have been investigated by both photo electron emission and photo absorption. Experimental spectra in the 2p energy range are discussed based on atomic multiplet models and Hartree- Fock calculations. The samples have been evaporated from an electron bombardment crucible and excited/ionized by monochromatized synchrotron radiation. Fundamental effects and the main interactions which govern the electronic structure of the 3d metal atoms are covered. Common spectral features and trends in the series are discussed as well as the importance of many body electron correlation effects. (orig.)

  18. Temporal structures in shell models

    DEFF Research Database (Denmark)

    Okkels, F.

    2001-01-01

    The intermittent dynamics of the turbulent Gledzer, Ohkitani, and Yamada shell-model is completely characterized by a single type of burstlike structure, which moves through the shells like a front. This temporal structure is described by the dynamics of the instantaneous configuration of the shell...

  19. Plate shell structures of glass

    DEFF Research Database (Denmark)

    Bagger, Anne

    to their curved shape. A plate shell structure maintains a high stiffness-to-weight ratio, while facilitating the use of plane structural elements. The study focuses on using laminated glass panes for the load bearing facets. Various methods of generating a plate shell geometry are suggested. Together with Ghent......, such as facet size, imperfections, and connection characteristics. The critical load is compared to that of a similar, but smoothly curved, shell structure. Based on the investigations throughout the study, a set of guidelines for the structural design of plate shells of glass is proposed....

  20. Electron Shell as a Resonator

    International Nuclear Information System (INIS)

    Karpeshin, F. F.

    2002-01-01

    Main principles of the resonance effect arising in the electron shells in interaction of the nuclei with electromagnetic radiation are analyzed and presented in the historical aspect. Principles of NEET are considered from a more general position, as compared to how this is usually presented. Characteristic features of NEET and its reverse, TEEN, as internal conversion processes are analyzed, and ways are offered of inducing them by laser radiation. The ambivalent role of the Pauli exclusion principles in NEET and TEEN processes is investigated.

  1. Energy-momentum structure of the krypton valence shell by electron-momentum spectroscopy

    International Nuclear Information System (INIS)

    Nicholson, R.; Braidwood, S.W.; McCathy, I.E.; Weigold, E.; Brunger, M.J.

    1996-03-01

    Momentum distributions and spectroscopic factors are obtained in a high resolution electron-momentum spectroscopy study of krypton at 1000 eV. The shapes and relative magnitudes of the momentum profiles are in good agreement with the results of calculations made within the distorted-wave impulse approximation (DWIA) framework. The DWIA describes the relative magnitudes of the 4p and 4s manifolds as well as giving a good representation of the shapes of the respective 4p and 4s cross sections. Results for the momentum profiles belonging to excited 2 P o and 2 S e manifolds are also presented. Spectroscopic factors for transitions belonging to the 2 p o and 2 S e manifolds are assigned up to a binding energy of 42 eV. The spectroscopic factor for the lowest 4s transition is 0.51 ± 0.01, whereas that for the ground-state 4p transition is 0.98± 0.01. Comparisons of the present binding energies and spectroscopic factors are made against the results of several many-body calculations and photoelectron spectroscopy (PES) results. In addition, a new procedure is outlined, utilising the experimental 4p and 4s manifold cross sections, that provides information on possible initial state configuration interaction effects in krypton. 50 refs., 2 tabs., 10 figs

  2. Satellite structure of the xenon valence shell by electron momentum spectroscopy

    International Nuclear Information System (INIS)

    Braidwood, S.; Brunger, M.; Weigold, E.

    1992-05-01

    Momentum distributions and spectroscopic factors are obtained in a high resolution electron momentum spectroscopy (EMS) study of xenon at 1000 eV. The shapes and relative magnitudes of the momentum profiles are in excellent agreement with distorted-wave impulse approximations using the target Dirac-Fock approximation. The DWDF approximation accurately describes the relative magnitudes of the 5p and 5s manifold cross sections as well as the shape of the 5s cross section. The use of nonrelativistic Hartree-Fock wavefunctions gives significantly poorer fits to the data. Spectroscopic factors for transitions belonging to the 2 S e 1/2 ,P 0 1/2,3/2 , and 2 D 3 3/2,5/2 manifolds are assigned up to a separation energy of 45 eV. The spectroscopic strength for the lowest 5s transition is 0.345 ± 0.010 whereas that for the ground state 5p transition is 0.96 ± 0.02. The 5s strength in the continuum above 33.1 eV is 0.115 ± 0.025 and that for the 5p manifold is only 0.03± 0.01. The first momentum profiles belong to excited 2 P o and 2 D e manifolds are obtained. The latter, which must be entirely due to d-wave correlations in the xenon ground state, are in good agreement with DF 5d momentum profiles. Comparison is made with several many-body calculations and agreement with the latest relativistic calculation is very good. 26 refs., 3 tabs., 5 figs

  3. On the atomic shell structure calculation (1)

    International Nuclear Information System (INIS)

    Choe Sun Chol

    1986-01-01

    We have considered the problem of atomic shell structure calculation using operator technique. We introduce reduced matrix elements of annihilation operators according to eg. (4). The normalized basis function is denoted as || ...>. The reduced matrix elements of the pair annihilation operators are expressed throw one-electron matrix elements. Some numerical results are represented and the problem of sign assignment is discussed. (author)

  4. The effect of oxide shell thickness on the structural, electronic, and optical properties of Si-SiO{sub 2} core-shell nano-crystals: A (time dependent)density functional theory study

    Energy Technology Data Exchange (ETDEWEB)

    Nazemi, Sanaz, E-mail: s.nazemi@ut.ac.ir, E-mail: pourfath@ut.ac.ir; Soleimani, Ebrahim Asl [School of Electrical and Computer Engineering, University of Tehran, Tehran 14395-515 (Iran, Islamic Republic of); Pourfath, Mahdi, E-mail: s.nazemi@ut.ac.ir, E-mail: pourfath@ut.ac.ir [School of Electrical and Computer Engineering, University of Tehran, Tehran 14395-515 (Iran, Islamic Republic of); Institute for Microelectronics, Technische Universität Wien, Wien A-1040 (Austria); Kosina, Hans [Institute for Microelectronics, Technische Universität Wien, Wien A-1040 (Austria)

    2016-04-14

    Due to their tunable properties, silicon nano-crystals (NC) are currently being investigated. Quantum confinement can generally be employed for size-dependent band-gap tuning at dimensions smaller than the Bohr radius (∼5 nm for silicon). At the nano-meter scale, however, increased surface-to-volume ratio makes the surface effects dominant. Specifically, in Si-SiO{sub 2} core-shell semiconductor NCs the interfacial transition layer causes peculiar electronic and optical properties, because of the co-existence of intermediate oxidation states of silicon (Si{sup n+}, n = 0–4). Due to the presence of the many factors involved, a comprehensive understanding of the optical properties of these NCs has not yet been achieved. In this work, Si-SiO{sub 2} NCs with a diameter of 1.1 nm and covered by amorphous oxide shells with thicknesses between 2.5 and 4.75 Å are comprehensively studied, employing density functional theory calculations. It is shown that with increased oxide shell thickness, the low-energy part of the optical transition spectrum of the NC is red shifted and attenuated. Moreover, the absorption coefficient is increased in the high-energy part of the spectrum which corresponds to SiO{sub 2} transitions. Structural examinations indicate a larger compressive stress on the central silicon cluster with a thicker oxide shell. Examination of the local density of states reveals the migration of frontier molecular orbitals from the oxide shell into the silicon core with the increase of silica shell thickness. The optical and electrical properties are explained through the analysis of the density of states and the spatial distribution of silicon sub-oxide species.

  5. Creep buckling of shell structures

    International Nuclear Information System (INIS)

    Miyazaki, Noriyuki; Hagihara, Seiya

    2015-01-01

    The present article contains a review of the literatures on the creep buckling of shell structures published from late 1950's to recent years. In this article, the creep buckling studies on circular cylindrical shells, spherical shells, partial cylindrical shells and other shells are reviewed in addition to creep buckling criteria. Creep buckling is categorized into two types. One is the creep buckling due to quasi-static instability, in which the critical time for creep buckling is determined by tracing a creep deformation versus time curve. The other is the creep buckling due to kinetic instability, in which the critical time can be determined by examining the shape of total potential energy in the vicinity of a quasi-static equilibrium state. Bifurcation buckling and snap-through buckling during creep deformation belong to this type of creep buckling. A few detailed descriptions are given to the bifurcation and snap-through type of creep buckling based on the present authors' works. (author)

  6. Hierarchical super-structure identified by polarized light microscopy, electron microscopy and nanoindentation: Implications for the limits of biological control over the growth mode of abalone sea shells

    Directory of Open Access Journals (Sweden)

    Schneider Andreas S

    2012-09-01

    Full Text Available Abstract Background Mollusc shells are commonly investigated using high-resolution imaging techniques based on cryo-fixation. Less detailed information is available regarding the light-optical properties. Sea shells of Haliotis pulcherina were embedded for polishing in defined orientations in order to investigate the interface between prismatic calcite and nacreous aragonite by standard materialographic methods. A polished thin section of the interface was prepared with a defined thickness of 60 μm for quantitative birefringence analysis using polarized light and LC-PolScope microscopy. Scanning electron microscopy images were obtained for comparison. In order to study structural-mechanical relationships, nanoindentation experiments were performed. Results Incident light microscopy revealed a super-structure in semi-transparent regions of the polished cross-section under a defined angle. This super-structure is not visible in transmitted birefringence analysis due to the blurred polarization of small nacre platelets and numerous organic interfaces. The relative orientation and homogeneity of calcite prisms was directly identified, some of them with their optical axes exactly normal to the imaging plane. Co-oriented "prism colonies" were identified by polarized light analyses. The nacreous super-structure was also visualized by secondary electron imaging under defined angles. The domains of the super-structure were interpreted to consist of crystallographically aligned platelet stacks. Nanoindentation experiments showed that mechanical properties changed with the same periodicity as the domain size. Conclusions In this study, we have demonstrated that insights into the growth mechanisms of nacre can be obtained by conventional light-optical methods. For example, we observed super-structures formed by co-oriented nacre platelets as previously identified using X-ray Photo-electron Emission Microscopy (X-PEEM [Gilbert et al., Journal of the

  7. Electron induced atomic inner-shell ionization

    International Nuclear Information System (INIS)

    Quarles, C.A.

    1974-01-01

    The current status of cross section measurements for atomic inner-shell ionization by electron bombardment is reviewed. Inner shell ionization studies using electrons as projectiles compliment the similar studies being done with heavy particles, and in addition can provide tests of the theory in those cases when relativistic effects and exchange effects are expected to be important. Both total cross sections and recently measured differential cross sections will be discussed and compared with existing theories where possible. Prospects for further experimental and theoretical work in this area of atomic physics using small electron accelerators will also be discussed

  8. Muonic atoms with vacant electron shells

    International Nuclear Information System (INIS)

    Bacher, R.; Gotta, D.; Simons, L.M.; Missimer, J.; Mukhopadhyay, N.C.

    1985-01-01

    We show that the cascade in muonic atoms with Z<20 ejects sufficient atomic electrons to ionize an isolated muonic atom completely. In gases, the rates with which electrons refill the atomic shell can be accurately deduced from measured and calculated electron transfer cross sections. Thus, we can conclude that completely ionized muonic atoms can be prepared in gases, and that they remain isolated for long enough times at attainable pressures to facilitate studies of fundamental interactions in muonic atoms

  9. Characterization of the electronic and magnetic structure of multifunctional NaREF{sub 4} (RE = rare earth) core-shell nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, Lilli; Kuepper, Karsten [Physics Department, University of Osnabrueck (Germany); Rinkel, Thorben; Haase, Markus [Institute of Chemistry, University of Osnabrueck (Germany); Chrobak, Artur [Institute of Physics, University of Silesia (Poland)

    2014-07-01

    Rare earth (RE) based nanoparticles of type NaREF{sub 4} have attracted lot of attention in the last few years due to their upconverting luminescence. Here, we want to concentrate on electronic and magnetic properties of NaREF{sub 4}/NaGdF{sub 4} nanocrystals, since the magnetic behaviour of these fluorescent nanoparticles are of utmost importance from fundamental and applicative point of view as well. Hexagonal β-phase nanocrystals (3-22 nm) were prepared and characterized by X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). A detailed study of the electronic structure and magnetic coupling phenomena of the different core-shell nanoparticles is performed using X-ray photoelectron spectroscopy (XPS), magnetometry (SQUID) and X-ray magnetic circular dichroism (XMCD). First SQUID measurements of NaEuF{sub 4}/NaGdF{sub 4} core-shell nanoparticles show butterfly shaped hysteresis loops at low temperature (2 K) in contrast to superparamagnetic behaviour observed for the corresponding ''pure'' NaEuF{sub 4} and NaGdF{sub 4} nanoparticles.

  10. Semiclassical shell structure in rotating Fermi systems

    International Nuclear Information System (INIS)

    Magner, A. G.; Sitdikov, A. S.; Khamzin, A. A.; Bartel, J.

    2010-01-01

    The collective moment of inertia is derived analytically within the cranking model for any rotational frequency of the harmonic-oscillator potential well and at a finite temperature. Semiclassical shell-structure components of the collective moment of inertia are obtained for any potential by using the periodic-orbit theory. We found semiclassically their relation to the free-energy shell corrections through the shell-structure components of the rigid-body moment of inertia of the statistically equilibrium rotation in terms of short periodic orbits. The shell effects in the moment of inertia exponentially disappear with increasing temperature. For the case of the harmonic-oscillator potential, one observes a perfect agreement of the semiclassical and quantum shell-structure components of the free energy and the moment of inertia for several critical bifurcation deformations and several temperatures.

  11. Structural shell analysis understanding and application

    CERN Document Server

    Blaauwendraad, Johan

    2014-01-01

    The mathematical description of the properties of a shell is much more elaborate than those of beam and plate structures. Therefore many engineers and architects are unacquainted with aspects of shell behaviour and design, and are not familiar with sufficiently reliable shell theories for the different shell types as derived in the middle of the 20th century. Rather than contributing to theory development, this university textbook focuses on architectural and civil engineering schools. Of course, practising professionals will profit from it as well. The book deals with thin elastic shells, in particular with cylindrical, conical and spherical types, and with elliptic and hyperbolic paraboloids. The focus is on roofs, chimneys, pressure vessels and storage tanks. Special attention is paid to edge bending disturbance zones, which is indispensable knowledge in FE meshing. A substantial part of the book results from research efforts in the mid 20th century at Delft University of Technology. As such, it is a valua...

  12. Amplitude structure of off-shell processes

    International Nuclear Information System (INIS)

    Fearing, H.W.; Goldstein, G.R.; Moravcsik, M.J.

    1984-01-01

    The structure of M matrices, or scattering amplitudes, and of potentials for off-shell processes is discussed with the objective of determining how one can obtain information on off-shell amplitudes of a process in terms of the physical observables of a larger process in which the first process is embedded. The procedure found is inevitably model dependent, but within a particular model for embedding, a determination of the physically measurable amplitudes of the larger process is able to yield a determination of the off-shell amplitudes of the embedded process

  13. Structural experiments with ice (composite) shells

    NARCIS (Netherlands)

    Belis, J.; Martens, K.; Van Lancker, B.; Pronk, A.; Zingoni, Alphose

    2016-01-01

    ABSTRACT: Ice can be a very suitable building material for temporary structures in a freezing environment. When water, mixed with small fibre reinforcements, is sprayed onto an inflatable membrane structure in suitable cold outdoor conditions, a thin shell is formed which increases thickness layer

  14. UHPFRC in large span shell structures

    NARCIS (Netherlands)

    Ter Maten, R.N.; Grunewald, S.; Walraven, J.C.

    2013-01-01

    Ultra-High Performance Fibre-Reinforced Concrete (UHPFRC) is an innovative concrete type with a high compressive strength and a far more durable character compared to conventional concrete. UHPFRC can be applied in structures with aesthetic appearance and high material efficiency. Shell structures

  15. Interplay of electronic and geometry shell effects in properties of neutral and charged Sr clusters

    DEFF Research Database (Denmark)

    Lyalin, Andrey; Solov'yov, Ilia; Solov'yov, Andrey V.

    2007-01-01

    that the size evolution of structural and electronic properties of strontium clusters is governed by an interplay of the electronic and geometry shell closures. Influence of the electronic shell effects on structural rearrangements can lead to violation of the icosahedral growth motif of strontium clusters......The optimized structure and electronic properties of neutral, singly, and doubly charged strontium clusters have been investigated using ab initio theoretical methods based on density-functional theory. We have systematically calculated the optimized geometries of neutral, singly, and doubly...... charged strontium clusters consisting of up to 14 atoms, average bonding distances, electronic shell closures, binding energies per atom, the gap between the highest occupied and the lowest unoccupied molecular orbitals, and spectra of the density of electronic states (DOS). It is demonstrated...

  16. Conceptual Design Tool for Concrete Shell Structures

    DEFF Research Database (Denmark)

    Holst, Malene Kirstine; Kirkegaard, Poul Henning

    2011-01-01

    This paper focuses on conceptual tools for concrete shell structures when working within the span of performance-based design and computational morphogenesis. The designer, referred to as the Architect-Engineer, works through several iterations parallel with aesthetic, functional and technical re...

  17. Preparation of porous carbon particle with shell/core structure

    Directory of Open Access Journals (Sweden)

    2007-05-01

    Full Text Available Porous carbon particles with a shell/core structure have been prepared successfully by controlled precipitation of the polymer from droplets of oil-in-water emulsion, followed by curing and carbonization. The droplets of the oil phase are composed of phenolic resin (PFR, a good solvent (ethyl acetate and porogen (Poly(methyl methacrylate, PMMA. The microstructure was characterized in detail by scanning electron microscopy (SEM, transmission electron microscopy (TEM, nitrogen adsorption, and thermo gravimetric analysis (TGA. The obtained carbon particles have a capsular structure with a microporous carbon shell and a mesoporous carbon core. The BET surface area and porous volume are calculated to be 499 m2g-1 and 0.56 cm3g-1, respectively. The effects of the amount of porogen (PMMA, co-solvent (acetone and surfactant on the resultant structure were studied in detail.

  18. Determination of Core-Shell Structures in Pd-Hg Nanoparticles by STEM-EDX

    DEFF Research Database (Denmark)

    Deiana, Davide; Verdaguer Casadevall, Arnau; Malacrida, Paolo

    2015-01-01

    The structural and elemental configuration of a high-performing Pd-Hg electrocatalyst for oxygen reduction to hydrogen peroxide has been studied by means of high-resolution scanning transmission electron microscopy. Pd-Hg nanoparticles are shown to have a crystalline core-shell structure, with a Pd...... core and a Pd-Hg ordered alloy shell. The ordered shell is responsible for the high oxygen reduction selectivity to H2O2....

  19. Cluster shell model: I. Structure of 9Be, 9B

    Science.gov (United States)

    Della Rocca, V.; Iachello, F.

    2018-05-01

    We calculate energy spectra, electromagnetic transition rates, longitudinal and transverse electron scattering form factors and log ft values for beta decay in 9Be, 9B, within the framework of a cluster shell model. By comparing with experimental data, we find strong evidence for the structure of these nuclei to be two α-particles in a dumbbell configuration with Z2 symmetry, plus an additional nucleon.

  20. Modified ferrite core-shell nanoparticles magneto-structural characterization

    Science.gov (United States)

    Klekotka, Urszula; Piotrowska, Beata; Satuła, Dariusz; Kalska-Szostko, Beata

    2018-06-01

    In this study, ferrite nanoparticles with core-shell structures and different chemical compositions of both the core and shell were prepared with success. Proposed nanoparticles have in the first and second series magnetite core, and the shell is composed of a mixture of ferrites with Fe3+, Fe2+ and M ions (where M = Co2+, Mn2+ or Ni2+) with a general composition of M0.5Fe2.5O4. In the third series, the composition is inverted, the core is composed of a mixture of ferrites and as a shell magnetite is placed. Morphology and structural characterization of nanoparticles were done using Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), and Infrared spectroscopy (IR). While room temperature magnetic properties were measured using Mössbauer spectroscopy (MS). It is seen from Mössbauer measurements that Co always increases hyperfine magnetic field on Fe atoms at RT, while Ni and Mn have opposite influences in comparison to pure Fe ferrite, regardless of the nanoparticles structure.

  1. Kinetic-energy density functional: Atoms and shell structure

    International Nuclear Information System (INIS)

    Garcia-Gonzalez, P.; Alvarellos, J.E.; Chacon, E.

    1996-01-01

    We present a nonlocal kinetic-energy functional which includes an anisotropic average of the density through a symmetrization procedure. This functional allows a better description of the nonlocal effects of the electron system. The main consequence of the symmetrization is the appearance of a clear shell structure in the atomic density profiles, obtained after the minimization of the total energy. Although previous results with some of the nonlocal kinetic functionals have given incipient structures for heavy atoms, only our functional shows a clear shell structure for most of the atoms. The atomic total energies have a good agreement with the exact calculations. Discussion of the chemical potential and the first ionization potential in atoms is included. The functional is also extended to spin-polarized systems. copyright 1996 The American Physical Society

  2. Electron energy spectrum in core-shell elliptic quantum wire

    Directory of Open Access Journals (Sweden)

    V.Holovatsky

    2007-01-01

    Full Text Available The electron energy spectrum in core-shell elliptic quantum wire and elliptic semiconductor nanotubes are investigated within the effective mass approximation. The solution of Schrodinger equation based on the Mathieu functions is obtained in elliptic coordinates. The dependencies of the electron size quantization spectrum on the size and shape of the core-shell nanowire and nanotube are calculated. It is shown that the ellipticity of a quantum wire leads to break of degeneration of quasiparticle energy spectrum. The dependences of the energy of odd and even electron states on the ratio between semiaxes are of a nonmonotonous character. The anticrosing effects are observed at the dependencies of electron energy spectrum on the transversal size of the core-shell nanowire.

  3. Methodology of shell structure reinforcement layout optimization

    Science.gov (United States)

    Szafrański, Tomasz; Małachowski, Jerzy; Damaziak, Krzysztof

    2018-01-01

    This paper presents an optimization process of a reinforced shell diffuser intended for a small wind turbine (rated power of 3 kW). The diffuser structure consists of multiple reinforcement and metal skin. This kind of structure is suitable for optimization in terms of selection of reinforcement density, stringers cross sections, sheet thickness, etc. The optimisation approach assumes the reduction of the amount of work to be done between the optimization process and the final product design. The proposed optimization methodology is based on application of a genetic algorithm to generate the optimal reinforcement layout. The obtained results are the basis for modifying the existing Small Wind Turbine (SWT) design.

  4. Ionization effects in electronic inner-shells of ionized atoms

    International Nuclear Information System (INIS)

    Shchornak, G.

    1983-01-01

    A review of the atomic physics of ionization atoms has been presented. Interaction and structure effects in atomic shells, correlated to the occurrence of vacancies in several subshells of the atom have been considered. The methods of calculations of atomic states and wave functions have been reviewed. The energy shift of characteristic X-rays is discussed as a function of the ionization stage of the atom. The influence of inner and outer-shell vacancies on the energy of the X-rays is shown in detail. The influence of chemical effects on the parameters of X-rays is also taken into account. Further on, the change of transition probabilities in radiative and non-radiative transitions by changing stage of ionization is discussed; and among them the leading part of Auger and Coster-Kronig transitions by the arearrangement of the atomic states is shown. The influence of non-radiative electronic transitions on ionization cross-sections for multiple ionization is discussed. Using these results, ionization cross-sections for direct and indirect processes for several ionization stages are given

  5. Modeling plate shell structures using pyFormex

    DEFF Research Database (Denmark)

    Bagger, Anne; Verhegghe, Benedict; Hertz, Kristian Dahl

    2009-01-01

    A shell structure made of glass combines a light-weight structural concept with glass’ high permeability to light. If the geometry of the structure is plane-based facetted (plate shell structure), the glass elements will be plane panes, and these glass panes will comprise the primary load...... (plate shells and triangulated lattice shells) may not differ in complexity regarding the topology, but when it comes to the practical generation of the geometry, e.g. in CAD, the plate shell is far more troublesome to handle than the triangulated geometry. The free software tool “pyFormex”, developed...

  6. Opal shell structures: direct assembly versus inversion approach.

    Science.gov (United States)

    Deng, Tian-Song; Sharifi, Parvin; Marlow, Frank

    2013-09-16

    Opal shell structures can be fabricated in two ways: By direct assembly from hollow spheres (hs-opal) or by infiltration of precursors into opal templates and inversion. The resulting lattice disturbances were characterized by scanning electron microscopy (SEM), optical microscopy, and transmission spectra. The hs-opal system shows much lower disturbances, for example, a lower number of cracks and lattice deformations. The strong suppression of crack formation in one of these inverse opal structures can be considered as promising candidates for the fabrication of more perfect photonic crystals. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Semiclassical shell structure and nuclear double-humped fission barriers

    Directory of Open Access Journals (Sweden)

    A. G. Magner

    2010-09-01

    Full Text Available We derived the semiclassical trace formulas for the level density as sums over periodic-orbit families and isolated orbits within the improved stationary phase method. Averaged level-density shell corrections and shell-structure energies are continuous through all symmetry-breaking (bifurcation points with the correct asymptotics of the standard stationary phase approach accounting for continuous symmetries. We found enhancement of the nuclear shell structure near bifurcations in the superdeformed region. Our semiclassical results for the averaged level densities with the gross-shell and more thin-shell structures and the energy shell corrections for critical deformations are in good agreement with the quantum calculations for several single-particle Hamiltonians, in particular for the potentials with a sharp spheroidal shape. Enhancement of the shell structure owing to bifurcations of the shortest 3-dimensional orbits from equatorial orbits is responsible for the second well of fission barrier in a superdeformation region.

  8. Atomistic tight-binding computations of the structural and optical properties of CdTe/CdX (X=S and Se)/ZnS core/shell/shell nanocrystals

    Science.gov (United States)

    Sukkabot, Worasak

    2018-05-01

    A study of CdTe/CdX (X=S and Se)/ZnS core/shell/shell nanocrystals is carried out using atomistic tight-binding theory and the configuration interaction method to provide information for applications in bioimaging, biolabeling, display devices and near-infrared electronic instruments. The calculations yield the dependences of the internal and external passivated shells on the natural behaviours of CdTe/CdX (X=S and Se)/ZnS core/shell/shell nanocrystals. The reduction of the optical band gaps is observed with increasing numbers of monolayers in the external ZnS shell due to quantum confinement. Interestingly, the optical band gaps of CdTe/CdS/ZnS core/shell/shell nanocrystals are greater than those of CdTe/CdSe/ZnS core/shell/shell nanocrystals. In the presence of an external ZnS-coated shell, electron-hole wave function overlaps, oscillation strengths, ground-state exchange energies and Stokes shift are improved, whereas ground-state coulomb energies and fine-structure splitting are reduced. The oscillation strengths, Stokes shift and fine-structure splitting are reduced with the increase in external ZnS shell thickness. The oscillation strengths, Stokes shift and fine-structure splitting of CdTe/CdS/ZnS core/shell/shell nanocrystals are larger than those of CdTe/CdSe/ZnS core/shell/shell nanocrystals. Reduction of the atomistic electron-hole interactions is observed with increasing external ZnS shell size. The strong electron-hole interactions are more probed in CdTe/CdS/ZnS core/shell/shell nanocrystals than in CdTe/CdSe/ZnS core/shell/shell nanocrystals.

  9. Average L-shell fluorescence, Auger, and electron yields

    International Nuclear Information System (INIS)

    Krause, M.O.

    1980-01-01

    The dependence of the average L-shell fluorescence and Auger yields on the initial vacancy distribution is shown to be small. By contrast, the average electron yield pertaining to both Auger and Coster-Kronig transitions is shown to display a strong dependence. Numerical examples are given on the basis of Krause's evaluation of subshell radiative and radiationless yields. Average yields are calculated for widely differing vacancy distributions and are intercompared graphically for 40 3 subshell yields in most cases of inner-shell ionization

  10. Photoionization of inner-shell electrons

    International Nuclear Information System (INIS)

    Cooper, J.W.

    1975-01-01

    The theory of photoionization is developed and key approximations are discussed. The formalism is fully relativistic and includes all multipoles of the radiation field, conditions that can be related at lower energies and for low Z materials. The theory can also be extended to include electron-electron correlation effects, and represents a zeroth-order approximation. Alternate ways of treating correlation effects are developed along these lines. A brief discussion is given of two methods that have been used to treat near-threshold absorption in solids and the relationship of these to the methods covered earlier is discussed. Examples are given of how well results calculated by various methods agree with experimental evidence. 5 figures, 76 references

  11. L-shell ionization by relativistic electrons

    International Nuclear Information System (INIS)

    Johnston, P.N.; Spicer, B.M.; Helstroom, R.

    1980-01-01

    Measurements of the relative x-ray production cross-sections Lsub(α)/Lsub(l), Lsub(β)/Lsub(α) and Lsub (γ)/Lsub(α) by relativistic electrons for the heavy elements Gd, Tm, Ta, Au, Pb, Bi and Th have been carried out. The ratios Lsub(β)/Lsub(α) and Lsub(α)/Lsub (l), are compared with previous experimental and theoretical work

  12. Structural Acoustic Physics Based Modeling of Curved Composite Shells

    Science.gov (United States)

    2017-09-19

    NUWC-NPT Technical Report 12,236 19 September 2017 Structural Acoustic Physics -Based Modeling of Curved Composite Shells Rachel E. Hesse...SUBTITLE Structural Acoustic Physics -Based Modeling of Curved Composite Shells 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT...study was to use physics -based modeling (PBM) to investigate wave propagations through curved shells that are subjected to acoustic excitation. An

  13. Integrable structure in discrete shell membrane theory.

    Science.gov (United States)

    Schief, W K

    2014-05-08

    We present natural discrete analogues of two integrable classes of shell membranes. By construction, these discrete shell membranes are in equilibrium with respect to suitably chosen internal stresses and external forces. The integrability of the underlying equilibrium equations is proved by relating the geometry of the discrete shell membranes to discrete O surface theory. We establish connections with generalized barycentric coordinates and nine-point centres and identify a discrete version of the classical Gauss equation of surface theory.

  14. Relativistic effects on inner-shell electron properties

    International Nuclear Information System (INIS)

    Desclaux, J.P.

    1976-01-01

    The influence of relativistic effects on hydrogen-like systems is first reviewed. After having considered one-electron systems, the influence of the other electrons is to be taken into account when considering inner ionization energy and ionization cross sections. Two-hole states in inner shells being then dealt with, the problem of angular momentum coupling among electrons can no longer be neglected. In an other way, this implies that wave functions are to be built on a jj basis instead of a ls one. Ksub(α)sup(h) hypersatellite spectra and KLL Auger transition energies are successively discussed

  15. Micromagnetic studies of three-dimensional pyramidal shell structures

    International Nuclear Information System (INIS)

    Knittel, A; Franchin, M; Fischbacher, T; Fangohr, H; Nasirpouri, F; Bending, S J

    2010-01-01

    We present a systematic numerical analysis of the magnetic properties of pyramidal-shaped core-shell structures in a size range below 400 nm. These are three-dimensional structures consisting of a ferromagnetic shell which is grown on top of a non-magnetic core. The standard micromagnetic model without the magnetocrystalline anisotropy term is used to describe the properties of the shell. We vary the thickness of the shell between the limiting cases of an ultra-thin shell and a conventional pyramid and delineate different stable magnetic configurations. We find different kinds of single-domain states, which predominantly occur at smaller system sizes. In analogy to equivalent states in thin square films we term these onion, flower, C and S states. At larger system sizes, we also observe two types of vortex states, which we refer to as symmetric and asymmetric vortex states. For a classification of the observed states, we derive a phase diagram that specifies the magnetic ground state as a function of structure size and shell thickness. The transitions between different ground states can be understood qualitatively. We address the issue of metastability by investigating the stability of all occurring configurations for different shell thicknesses. For selected geometries and directions hysteresis measurements are analysed and discussed. We observe that the magnetic behaviour changes distinctively in the limit of ultra-thin shells. The study has been motivated by the recent progress made in the growth of faceted core-shell structures.

  16. Adsorption of copper to different biogenic oyster shell structures

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Qiong; Chen, Jie [College of Materials Science and Engineering, Fuzhou University, New Campus, Minhou, Fujian Province 350108 (China); Clark, Malcolm [Marine Ecology Research Centre, School of Environment, Science and Engineering, Southern Cross University, P.O. Box 157, Lismore, NSW 2480 (Australia); Yu, Yan, E-mail: yuyan_1972@126.com [College of Materials Science and Engineering, Fuzhou University, New Campus, Minhou, Fujian Province 350108 (China)

    2014-08-30

    Graphical abstract: - Highlights: • Adsorption of copper to waste oyster shell occurs rapidly at pH 5.5. • Copper adsorbs to the different structures of oyster shell at different rates. • The prismatic layer dominates copper sorption rather than the nacreous layer. • SEM analysis shows a porous open network structure to the prismatic layer. • Surface ζ-potentials establish electrostatic attraction to drive copper sorption. - Abstract: The removal of copper from solution by oyster shell powder was investigated for potential wastewater treatment uses. In particular, adsorption behavior differences between the prismatic (PP) and nacreous (NP) shell layers, and how this affects copper removal, were investigated. Experimental results indicated that copper adsorption was highly pH-dependent with optimal copper removal at pH 5.5, where the powdered whole raw shell (RP) removed up to 99.9% of the copper within 24 h at a 10 mg/L initial copper concentration. Langmuir and Freundlich models were used to analyze the isotherm PP, NP and RP data. These results showed a strong homogeneous Langmuir model for low initial copper concentrations (5–30 mg/L) to both RP and PP layer, while strong agreement with a heterogeneous Freundlich model for high initial copper concentrations (30–200 mg/L); nevertheless, a homogeneous Langmuir model provided the best fit for the more dense NP layer across the initial concentration range (5–200 mg/L). The distribution coefficient (K{sub d}) value of PP layer for each initial concentration investigated was substantially higher than the NP layer and it was also found that the PP layer dominated the adsorption process with an adsorption capacity of 8.9 mg/g, while the adsorption capacity of the NP layer was 2.6 mg/g. These differences are believed to be because of the more porous structure of the PP layer, which was confirmed by scanning electron microscopy, infrared spectroscopy, energy-dispersive X-ray spectroscopy, and

  17. Adsorption of copper to different biogenic oyster shell structures

    International Nuclear Information System (INIS)

    Wu, Qiong; Chen, Jie; Clark, Malcolm; Yu, Yan

    2014-01-01

    Graphical abstract: - Highlights: • Adsorption of copper to waste oyster shell occurs rapidly at pH 5.5. • Copper adsorbs to the different structures of oyster shell at different rates. • The prismatic layer dominates copper sorption rather than the nacreous layer. • SEM analysis shows a porous open network structure to the prismatic layer. • Surface ζ-potentials establish electrostatic attraction to drive copper sorption. - Abstract: The removal of copper from solution by oyster shell powder was investigated for potential wastewater treatment uses. In particular, adsorption behavior differences between the prismatic (PP) and nacreous (NP) shell layers, and how this affects copper removal, were investigated. Experimental results indicated that copper adsorption was highly pH-dependent with optimal copper removal at pH 5.5, where the powdered whole raw shell (RP) removed up to 99.9% of the copper within 24 h at a 10 mg/L initial copper concentration. Langmuir and Freundlich models were used to analyze the isotherm PP, NP and RP data. These results showed a strong homogeneous Langmuir model for low initial copper concentrations (5–30 mg/L) to both RP and PP layer, while strong agreement with a heterogeneous Freundlich model for high initial copper concentrations (30–200 mg/L); nevertheless, a homogeneous Langmuir model provided the best fit for the more dense NP layer across the initial concentration range (5–200 mg/L). The distribution coefficient (K d ) value of PP layer for each initial concentration investigated was substantially higher than the NP layer and it was also found that the PP layer dominated the adsorption process with an adsorption capacity of 8.9 mg/g, while the adsorption capacity of the NP layer was 2.6 mg/g. These differences are believed to be because of the more porous structure of the PP layer, which was confirmed by scanning electron microscopy, infrared spectroscopy, energy-dispersive X-ray spectroscopy, and

  18. Superconducting transition temperature and the formation of closed electron shells in the atoms of superconducting compounds

    International Nuclear Information System (INIS)

    Chapnik, I.M.

    1985-01-01

    The relationship between the regularities in the tansition temperature (T/sub c/) values in analogous compounds (having the same structure and stoichiometry) and the formation of the closed electron shells outside inert gas shells in the atoms of the variable component of the 158 intermetallic superconducting compounds has been discussed. The T/sub c/ data for compounds of the elements from the first long period of the Periodic Table (K to Se) are compared with the T/sub c/ data for the analogous compounds of the elements from the second long period (Rb to Te)

  19. Gross shell structure of moments of inertia

    International Nuclear Information System (INIS)

    Deleplanque, M.A.; Frauendorf, S.; Pashkevich, V.V.; Chu, S.Y.; Unzhakova, A.

    2002-01-01

    Average yrast moments of inertia at high spins, where the pairing correlations are expected to be largely absent, were found to deviate from the rigid-body values. This indicates that shell effects contribute to the moment of inertia. We discuss the gross dependence of moments of inertia and shell energies on the neutron number in terms of the semiclassical periodic orbit theory. We show that the ground-state shell energies, nuclear deformations and deviations from rigid-body moments of inertia are all due to the same periodic orbits

  20. Cross Sections for Inner-Shell Ionization by Electron Impact

    Energy Technology Data Exchange (ETDEWEB)

    Llovet, Xavier, E-mail: xavier@ccit.ub.edu [Centres Científics i Tecnològics, Universitat de Barcelona, Lluís Solé i Sabarís 1-3, 08028 Barcelona (Spain); Powell, Cedric J. [Materials Measurement Science Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8370 (United States); Salvat, Francesc [Facultat de Física (ECM and ICC), Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain); Jablonski, Aleksander [Institute of Physical Chemistry, Polish Academy of Sciences, ul. Kasprzaka 44/52, 01-224 Warsaw (Poland)

    2014-03-15

    An analysis is presented of measured and calculated cross sections for inner-shell ionization by electron impact. We describe the essentials of classical and semiclassical models and of quantum approximations for computing ionization cross sections. The emphasis is on the recent formulation of the distorted-wave Born approximation by Bote and Salvat [Phys. Rev. A 77, 042701 (2008)] that has been used to generate an extensive database of cross sections for the ionization of the K shell and the L and M subshells of all elements from hydrogen to einsteinium (Z = 1 to Z = 99) by electrons and positrons with kinetic energies up to 1 GeV. We describe a systematic method for evaluating cross sections for emission of x rays and Auger electrons based on atomic transition probabilities from the Evaluated Atomic Data Library of Perkins et al. [Lawrence Livermore National Laboratory, UCRL-ID-50400, 1991]. We made an extensive comparison of measured K-shell, L-subshell, and M-subshell ionization cross sections and of Lα x-ray production cross sections with the corresponding calculated cross sections. We identified elements for which there were at least three (for K shells) or two (for L and M subshells) mutually consistent sets of cross-section measurements and for which the cross sections varied with energy as expected by theory. The overall average root-mean-square deviation between the measured and calculated cross sections was 10.9% and the overall average deviation was −2.5%. This degree of agreement between measured and calculated ionization and x-ray production cross sections was considered to be very satisfactory given the difficulties of these measurements.

  1. Cu-Ag core–shell nanoparticles with enhanced oxidation stability for printed electronics

    International Nuclear Information System (INIS)

    Lee, Changsoo; Kim, Na Rae; Koo, Jahyun; Lee, Yung Jong; Lee, Hyuck Mo

    2015-01-01

    In this work, we synthesized uniform Cu–Ag core–shell nanoparticles using a facile two-step process that consists of thermal decomposition and galvanic displacement methods. The core–shell structure of these nanoparticles was confirmed through characterization using transmission electron microscopy, energy-dispersive spectroscopy, and x-ray diffraction. Furthermore, we investigated the oxidation stability of the Cu–Ag core–shell nanoparticles in detail. Both qualitative and quantitative x-ray photoelectron spectroscopy analyses confirm that the Cu–Ag core–shell nanoparticles have considerably higher oxidation stability than Cu nanoparticles. Finally, we formulated a conductive ink using the synthesized nanoparticles and coated it onto glass substrates. Following the sintering process, we compared the resistivity of the Cu–Ag core–shell nanoparticles with that of the Cu nanoparticles. The results of this study clearly show that the Cu–Ag core–shell nanoparticles can potentially be used as an alternative to Ag nanoparticles because of their superior oxidation stability and electrical properties. (paper)

  2. Gap state related blue light emitting boron-carbon core shell structures

    International Nuclear Information System (INIS)

    Singh, Paviter; Kaur, Manpreet; Singh, Bikramjeet; Kaur, Gurpreet; Singh, Kulwinder; Kumar, Akshay; Kumar, Manjeet; Bala, Rajni; Thakur, Anup

    2016-01-01

    Boron-carbon core shell structures have been synthesized by solvo-thermal synthesis route. The synthesized material is highly pure. X-ray diffraction analysis confirms the reduction of reactants in to boron and carbon. Scanning Electron Microscopy (SEM) analysis showed that the shell is uniform with average thickness of 340 nm. Photo luminescence studies showed that the material is blue light emitting with CIE color coordinates: x=0.16085, y=0.07554.

  3. Shell model description of band structure in 48Cr

    International Nuclear Information System (INIS)

    Vargas, Carlos E.; Velazquez, Victor M.

    2007-01-01

    The band structure for normal and abnormal parity bands in 48Cr are described using the m-scheme shell model. In addition to full fp-shell, two particles in the 1d3/2 orbital are allowed in order to describe intruder states. The interaction includes fp-, sd- and mixed matrix elements

  4. Electromagnetic and structural interaction analysis of curved shell structures

    International Nuclear Information System (INIS)

    Horie, T.; Niho, T.

    1993-01-01

    This paper describes a finite element formulation of the eddy current and structure coupled problem for curved shell structures. Coupling terms produced by curved geometry as well as flat plate geometry were obtained. Both matrix equations for eddy current and structure were solved simultaneously using coupling sub-matrices. TEAM Workshop bench mark problem 16 was solved to verify the formulation and the computer code. Agreement with experimental results was very good for such plate problem. A coupled problem for cylindrical shell structure was also analyzed. Influence of each coupling term was examined. The next topic is the eigenvalues of the coupled equations. Although the coupled matrix equations are not symmetric, symmetry was obtained by introducing a symmetrizing variable. The eigenvalues of the coupled matrix equations are different from those obtained from the uncoupled equations because of the influence of the coupling sub-matrix components. Some parameters obtained by the eigenvalue analysis have characteristics of parameters which indicate the intensity of electromagnetic structural coupling effect. (author)

  5. The influence of MOVPE growth conditions on the shell of core-shell GaN microrod structures

    Science.gov (United States)

    Schimpke, Tilman; Avramescu, Adrian; Koller, Andreas; Fernando-Saavedra, Amalia; Hartmann, Jana; Ledig, Johannes; Waag, Andreas; Strassburg, Martin; Lugauer, Hans-Jürgen

    2017-05-01

    A core-shell geometry is employed for most next-generation, three-dimensional opto-electric devices based on III-V semiconductors and grown by metal organic vapor phase epitaxy (MOVPE). Controlling the shape of the shell layers is fundamental for device optimization, however no detailed analysis of the influence of growth conditions has been published to date. We study homogeneous arrays of gallium nitride core-shell microrods with height and diameter in the micrometer range and grown in a two-step selective area MOVPE process. Changes in shell shape and homogeneity effected by deliberately altered shell growth conditions were accurately assessed by digital analysis of high-resolution scanning electron microscope images. Most notably, two temperature regimes could be established, which show a significantly different behavior with regard to material distribution. Above 900 °C of wafer carrier temperature, the shell thickness along the growth axis of the rods was very homogeneous, however variations between vicinal rods increase. In contrast, below 830 °C the shell thickness is higher close to the microrod tip than at the base of the rods, while the lateral homogeneity between neighboring microrods is very uniform. This temperature effect could be either amplified or attenuated by changing the remaining growth parameters such as reactor pressure, structure distance, gallium precursor, carrier gas composition and dopant materials. Possible reasons for these findings are discussed with respect to GaN decomposition as well as the surface and gas phase diffusion of growth species, leading to an improved control of the functional layers in next-generation 3D V-III devices.

  6. Core/shell structured ZnO/SiO2 nanoparticles: Preparation, characterization and photocatalytic property

    International Nuclear Information System (INIS)

    Zhai Jing; Tao Xia; Pu Yuan; Zeng Xiaofei; Chen Jianfeng

    2010-01-01

    ZnO nanoparticles were prepared by a simple chemical synthesis route. Subsequently, SiO 2 layers were successfully coated onto the surface of ZnO nanoparticles to modify the photocatalytic activity in acidic or alkaline solutions. The obtained particles were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive spectrometry (EDS) and zeta potential. It was found that ultrafine core/shell structured ZnO/SiO 2 nanoparticles were successfully obtained. The photocatalytic performance of ZnO/SiO 2 core/shell structured nanoparticles in Rhodamine B aqueous solution at varied pH value were also investigated. Compared with uncoated ZnO nanoparticles, core/shell structured ZnO/SiO 2 nanoparticles with thinner SiO 2 shell possess improved stability and relatively better photocatalytic activity in acidic or alkaline solutions, which would broaden its potential application in pollutant treatment.

  7. Process to make core-shell structured nanoparticles

    Science.gov (United States)

    Luhrs, Claudia; Phillips, Jonathan; Richard, Monique N

    2014-01-07

    Disclosed is a process for making a composite material that contains core-shell structured nanoparticles. The process includes providing a precursor in the form of a powder a liquid and/or a vapor of a liquid that contains a core material and a shell material, and suspending the precursor in an aerosol gas to produce an aerosol containing the precursor. In addition, the process includes providing a plasma that has a hot zone and passing the aerosol through the hot zone of the plasma. As the aerosol passes through the hot zone of the plasma, at least part of the core material and at least part of the shell material in the aerosol is vaporized. Vapor that contains the core material and the shell material that has been vaporized is removed from the hot zone of the plasma and allowed to condense into core-shell structured nanoparticles.

  8. Snap-Through Buckling Problem of Spherical Shell Structure

    Directory of Open Access Journals (Sweden)

    Sumirin Sumirin

    2014-12-01

    Full Text Available This paper presents results of a numerical study on the nonlinear behavior of shells undergoing snap-through instability. This research investigates the problem of snap-through buckling of spherical shells applying nonlinear finite element analysis utilizing ANSYS Program. The shell structure was modeled by axisymmetric thin shell of finite elements. Shells undergoing snap-through buckling meet with significant geometric change of their physical configuration, i.e. enduring large deflections during their deformation process. Therefore snap-through buckling of shells basically is a nonlinear problem. Nonlinear numerical operations need to be applied in their analysis. The problem was solved by a scheme of incremental iterative procedures applying Newton-Raphson method in combination with the known line search as well as the arc- length methods. The effects of thickness and depth variation of the shell is taken care of by considering their geometrical parameter l. The results of this study reveal that spherical shell structures subjected to pressure loading experience snap-through instability for values of l≥2.15. A form of ‘turn-back’ of the load-displacement curve took place at load levels prior to the achievement of the critical point. This phenomenon was observed for values of l=5.0 to l=7.0.

  9. Shell structure in superdeformed nuclei at high rotational frequencies

    International Nuclear Information System (INIS)

    Ploszajczak, M.

    1980-01-01

    Properties of the shell structure in superdeformed nuclei at high rotational frequencies are discussed. Moreover, stability of the high spin compound nucleus with respect to the fission and the emission of light particles is investigated. (author)

  10. Interface Fracture in Adhesively Bonded Shell Structures

    DEFF Research Database (Denmark)

    Jensen, Henrik Myhre

    2008-01-01

    Two methods for the prediction of crack propagation through the interface of adhesively bonded shells are discussed. One is based on a fracture mechanics approach; the other is based on a cohesive zone approach. Attention is focussed on predicting the shape of the crack front and the critical...

  11. Methanol oxidation reaction on core-shell structured Ruthenium-Palladium nanoparticles: Relationship between structure and electrochemical behavior

    Science.gov (United States)

    Kübler, Markus; Jurzinsky, Tilman; Ziegenbalg, Dirk; Cremers, Carsten

    2018-01-01

    In this work the relationship between structural composition and electrochemical characteristics of Palladium(Pd)-Ruthenium(Ru) nanoparticles during alkaline methanol oxidation reaction is investigated. The comparative study of a standard alloyed and a precisely Ru-core-Pd-shell structured catalyst allows for a distinct investigation of the electronic effect and the bifunctional mechanism. Core-shell catalysts benefit from a strong electronic effect and an efficient Pd utilization. It is found that core-shell nanoparticles are highly active towards methanol oxidation reaction for potentials ≥0.6 V, whereas alloyed catalysts show higher current outputs in the lower potential range. However, differential electrochemical mass spectrometry (DEMS) experiments reveal that the methanol oxidation reaction on core-shell structured catalysts proceeds via the incomplete oxidation pathway yielding formaldehyde, formic acid or methyl formate. Contrary, the alloyed catalyst benefits from the Ru atoms at its surface. Those are found to be responsible for high methanol oxidation activity at lower potentials as well as for complete oxidation of CH3OH to CO2 via the bifunctional mechanism. Based on these findings a new Ru-core-Pd-shell-Ru-terrace catalyst was synthesized, which combines the advantages of the core-shell structure and the alloy. This novel catalyst shows high methanol electrooxidation activity as well as excellent selectivity for the complete oxidation pathway.

  12. Radar attenuation in Europa's ice shell: obstacles and opportunities for constraining shell thickness and thermal structure

    Science.gov (United States)

    Kalousova, Klara; Schroeder, Dustin M.; Soderlund, Krista M.; Sotin, Christophe

    2016-10-01

    With its strikingly young surface and possibly recent endogenic activity, Europa is one of the most exciting bodies within our Solar System and a primary target for spacecraft exploration. Future missions to Europa are expected to carry ice penetrating radar instruments which are powerful tools to investigate the subsurface thermophysical structure of its ice shell.Several authors have addressed the 'penetration depth' of radar sounders at icy moons, however, the concept and calculation of a single value penetration depth is a potentially misleading simplification since it ignores the thermal and attenuation structure complexity of a realistic ice shell. Here we move beyond the concept of a single penetration depth by exploring the variation in two-way radar attenuation for a variety of potential thermal structures of Europa's ice shell as well as for a low loss and high loss temperature-dependent attenuation model. The possibility to detect brines is also investigated.Our results indicate that: (i) for all ice shell thicknesses investigated (5-30 km), a nominal satellite-borne radar sounder will penetrate between 15% and 100% of the total thickness, (ii) the maximum penetration depth strongly varies laterally with the deepest penetration possible through the cold downwellings, (iii) the direct detection of the ice/ocean interface might be possible for shells of up to 15 km if the radar signal travels through the cold downwelling, (iv) even if the ice/ocean interface is not detected, the penetration through most of the shell could constrain the deep shell structure through the loss of signal, and (v) for all plausible ice shells the two-way attenuation to the eutectic point is ≤30 dB which shows a robust potential for longitudinal investigation of the ice shell's shallow structure.Part of this work has been performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract to NASA. K.K. acknowledges support by the Grant Agency of the

  13. Topology optimization of 3D shell structures with porous infill

    DEFF Research Database (Denmark)

    Clausen, Anders; Andreassen, Erik; Sigmund, Ole

    2017-01-01

    This paper presents a 3D topology optimization approach for designing shell structures with a porous or void interior. It is shown that the resulting structures are significantly more robust towards load perturbations than completely solid structures optimized under the same conditions. The study...... indicates that the potential benefit of using porous structures is higher for lower total volume fractions. Compared to earlier work dealing with 2D topology optimization, we found several new effects in 3D problems. Most notably, the opportunity for designing closed shells significantly improves...

  14. Ag@ZnO core-shell nanoparticles study by first principle: The structural, magnetic and optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Hai-Xia [Department of Physics, University of Science and Technology Beijing, Beijing 100083 (China); Wang, Xiao-Xu [Department of Physics, University of Science and Technology Beijing, Beijing 100083 (China); Beijing Computing Center, Beijing 100094 (China); Hu, Yao-Wen [Department of Physics, Tsinghua University, Beijing 100084 (China); Song, Hong-Quan; Huo, Jin-Rong; Li, Lu [Department of Physics, University of Science and Technology Beijing, Beijing 100083 (China); Qian, Ping, E-mail: ustbqianp@163.com [Department of Physics, University of Science and Technology Beijing, Beijing 100083 (China); Song, Yu-Jun [Department of Physics, University of Science and Technology Beijing, Beijing 100083 (China)

    2016-12-15

    Ag@ZnO core-shell nanoparticles of around 72 atoms have been investigated by the density functional theory, revealing proving for the first time that the core-shell structure exhibits a shrinkage phenomenon from outer shell in agreement with the other studies in literatures. Our calculations predict that the Ag@ZnO core-shell structure is a ferromagnetic spin polarized state, and the magnetism mainly stems from the spin splitting of 2p electrons of O atoms. In addition, the total and partial DOS of Ag@ZnO indicate that the nanostructure is a half-metallic nanoparticle and has the characters of the p-type semiconductor. Furthermore, the optical properties calculations show that the absorption edge of Ag@ZnO have a red shift and good photocatalysis compare to that of the bulk ZnO. These results of the Ag@ZnO core-shell structure obtain a well agreement with the experimental measurement. - Graphical abstract: Geometric structure of (a) Ag@ZnO core-shell nanostructure; (b) the core of Ag; (c) the shell of ZnO The core-shell nanoparticle Ag@ZnO contains Ag inner core of radius of 4 Å and ZnO outer shell with thickness of 2 Å. Ag@ZnO core-shell nanoparticles of around 72 atoms have been proved for the first time that the core-shell structure exhibit a shrinkage phenomenon from outer shell. Our calculations predict that the Ag@ZnO core-shell structure is a half-metallic nanoparticle and has the characters of the p-type semiconductor. The absorption edge of Ag@ZnO have a red shift and get good photo-catalysis compare to that of the bulk ZnO.

  15. Controlling interface characteristics by adjusting core-shell structure

    International Nuclear Information System (INIS)

    Chang, H.Y.; Cheng, S.Y.; Sheu, C.I.

    2004-01-01

    Most grain boundary layer ceramics comprise semiconductive/conductive grains and insulated grain boundaries. Such a structure can be theoretically regarded as a shell (grain boundary layer) surrounds a core (conductive or semiconductive grain). The core-shell structure of titanium (Ti)-strontium titanate (ST) is composed of three zones - ST, non-stoichiometric strontium-titanium oxide and Ti, in order from shell to core. It was successfully prepared using a hydrothermal method. The Ti-ST core-shell structure was sintered in a reducing atmosphere and then annealed in air to achieve the metal-insulator-metal structure (MIM structure). The resulting MIM structure, annealed in air, changes with the oxygen stoichiometry of the ST shell (insulator layer) at various temperatures, which is thus used to tune its electrical characteristics. The characteristics exhibit nonlinear behavior. Accordingly, the thickness of the insulator layer can be adjusted in various annealing atmospheres and at various temperatures to develop various interfacial devices, such as varistors, capacitors and thermistors, without the use of complex donor/acceptor doping technology

  16. Controllable synthesis and characterization of novel copper-carbon core-shell structured nanoparticles

    International Nuclear Information System (INIS)

    Zhai, Jing; Tao, Xia; Pu, Yuan; Zeng, Xiao-Fei; Chen, Jian-Feng

    2011-01-01

    Highlights: → We reported a facile, green and cheap hydrothermal method to obtain novel copper-carbon core-shell nanoparticles. → The as-formed particles with controllable size and morphology are antioxidant. → The particles with organic-group-loaded surfaces and protective shells are expected to be applied in fields of medicine, electronics, sensors and lubricant. -- Abstract: A facile hydrothermal method was developed for preparing copper-carbon core-shell structured particles through a reaction at 160 o C in which glucose, copper sulfate pentahydrate and cetyltrimethylammonium bromide were used as starting materials. The original copper-carbon core-shell structured particles obtained were sized of 100-250 nm. The thickness of carbonaceous shells was controlled ranging from 25 to 100 nm by adjusting the hydrothermal duration time and the concentrations of glucose in the process. Products were characterized with transmission electron microscopy, X-ray diffraction, energy dispersive spectroscopy, Fourier transform infrared spectroscopy. Since no toxic materials were involved in the preparation, particles with stable carbonaceous framework and reactive surface also showed promising applications in medicine, electronics, sensors, lubricant, etc.

  17. Controllable synthesis and characterization of novel copper-carbon core-shell structured nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Zhai, Jing [Sin-China Nano Technology Center, Key Lab for Nanomaterials, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Research Center of the Ministry of Education for High Gravity Engineering and Technology, Beijing University of Chemical Technology, No. 15 Beisanhuan Dong Lu, Beijing 100029 (China); Tao, Xia; Pu, Yuan; Zeng, Xiao-Fei [Sin-China Nano Technology Center, Key Lab for Nanomaterials, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Chen, Jian-Feng, E-mail: chenjf@mail.buct.edu.cn [Research Center of the Ministry of Education for High Gravity Engineering and Technology, Beijing University of Chemical Technology, No. 15 Beisanhuan Dong Lu, Beijing 100029 (China)

    2011-06-15

    Highlights: {yields} We reported a facile, green and cheap hydrothermal method to obtain novel copper-carbon core-shell nanoparticles. {yields} The as-formed particles with controllable size and morphology are antioxidant. {yields} The particles with organic-group-loaded surfaces and protective shells are expected to be applied in fields of medicine, electronics, sensors and lubricant. -- Abstract: A facile hydrothermal method was developed for preparing copper-carbon core-shell structured particles through a reaction at 160 {sup o}C in which glucose, copper sulfate pentahydrate and cetyltrimethylammonium bromide were used as starting materials. The original copper-carbon core-shell structured particles obtained were sized of 100-250 nm. The thickness of carbonaceous shells was controlled ranging from 25 to 100 nm by adjusting the hydrothermal duration time and the concentrations of glucose in the process. Products were characterized with transmission electron microscopy, X-ray diffraction, energy dispersive spectroscopy, Fourier transform infrared spectroscopy. Since no toxic materials were involved in the preparation, particles with stable carbonaceous framework and reactive surface also showed promising applications in medicine, electronics, sensors, lubricant, etc.

  18. Vibrations of composite circular shell structures due to transient loads

    International Nuclear Information System (INIS)

    Schrader, K.-H.; Krutzik, N.; Winkel, G.

    1975-01-01

    Referring to a container consisting of different shell structures - such as spherical, cylindrical and conical shells - the dynamic behavior of coupled spatial shell structures due to transient loads will be investigated. The spatial structure including the filling of water will be idealized as a three-dimensional model consisting of ring elements. The influence of the water filling on the vibrations will be considered by virtual masses added to the shell structures. In circular direction as well as in meridional direction a consistent mass model has been used. By variation of the virtual masses it will be clarified, how these additional masses influence the vibrational behavior of the composed system. Another aspect which will be investigated is the influence of different stiffnesses of substructures or parts of substructures on the natural frequencies, and on their affiliated eigensystems. Furthermore, the maximum and minimum stresses in the structures caused by transient loads acting on the inner surface of the shells will be explored. Here it seems to be possible to locate an area of maximum strain. Rotational loads as well as nonrotational loads will be considered

  19. Investigation of the structure change of atomic shells due to uranium ionization by the Dirac-Fock-Slater method

    International Nuclear Information System (INIS)

    Shchornak, G.

    1979-01-01

    The influence of outer vacancies in the atomic shells of uranium on the atomic shell structure is claculated by the Dirac-Fock-Slater method. It is found out that the energy of the X-ray transitions increases due to the detachment of the electrons with the lowest binding energies. The electron detachment from the subshells of the 4f level gives rise to negative energy shifts of the X-ray transitions.(author)

  20. Core-shell SrTiO3/graphene structure by chemical vapor deposition for enhanced photocatalytic performance

    Science.gov (United States)

    He, Chenye; Bu, Xiuming; Yang, Siwei; He, Peng; Ding, Guqiao; Xie, Xiaoming

    2018-04-01

    Direct growth of high quality graphene on the surface of SrTiO3 (STO) was realized through chemical vapor deposition (CVD), to construct few-layer 'graphene shell' on every STO nanoparticle. The STO/graphene composite shows significantly enhanced UV light photocatalytic activity compared with the STO/rGO reference. Mechanism analysis confirms the role of special core-shell structure and chemical bond (Tisbnd C) for rapid interfacial electron transfer and effective electron-hole separation.

  1. Study of inter sub-shell and inter shell electron correlations in 4d open-shell heavy atomic ions

    International Nuclear Information System (INIS)

    Koike, Fumihiro

    2009-01-01

    The effect of correlations between 4p, 4d, and 4f has been studied extensively. The characteristic spectral structures of 4p - 4d and 4d - 4f optical transitions, due to the unique structures of N = 4 open sub-shells in heavy atomic ions, have been studied theoretically. To gain an insight of this effect, a series of careful MCDF calculations for 4d q (q = 0 to 10) atomic ions with atomic numbers Z = 48 to 56 has been carried out. The difference of orbital energy differences between 4p and 4d orbitals and 4d and 4f orbitals coincidently falls within the range of a few % for almost all the atomic ions investigated. The 4p 6 4d4f and 4p 5 4d 3 configurations may mix strongly, and the optical 4p - 4d and 4d - 4f transitions may take place coherently, providing us with quite a peculiar EUV emission spectrum. The effect of spectral narrowing and shift is expected to be quite common to the atomic specieds with the atomic numbers in the range Z = 48 to 56.

  2. Overview of Hanford Single Shell Tank (SST) Structural Integrity

    Energy Technology Data Exchange (ETDEWEB)

    Rast, Richard S.; Washenfelder, Dennis J.; Johnson, Jeremy M.

    2013-11-14

    To improve the understanding of the single-shell tanks (SSTs) integrity, Washington River Protection Solutions, LLC (WRPS), the USDOE Hanford Site tank contractor, developed an enhanced Single-Shell Tank Integrity Project (SSTIP) in 2009. An expert panel on SST integrity, consisting of various subject matters experts in industry and academia, was created to provide recommendations supporting the development of the project. This panel developed 33 recommendations in four main areas of interest: structural integrity, liner degradation, leak integrity and prevention, and mitigation of contamination migration, Seventeen of these recommendations were used to develop the basis for the M-45-10-1 Change Package for the Hanford Federal Agreement and Compliance Order, which is also known as the Tri-Party Agreement. The structural integrity of the tanks is a key element in completing the cleanup mission at the Hanford Site. There are eight primary recommendations related to the structural integrity of Hanford Single-Shell Tanks. Six recommendations are being implemented through current and planned activities. The structural integrity of the Hanford is being evaluated through analysis, monitoring, inspection, materials testing, and construction document review. Structural evaluation in the form of analysis is performed using modern finite element models generated in ANSYS. The analyses consider in-situ, thermal, operating loads and natural phenomena such as earthquakes. Structural analysis of 108 of 149 Hanford Single-Shell Tanks has concluded that the tanks are structurally sound and meet current industry standards. Analysis of the remaining Hanford Single-Shell Tanks is scheduled for FY2014. Hanford Single-Shell Tanks are monitored through a dome deflection program. The program looks for deflections of the tank dome greater than 1/4 inch. No such deflections have been recorded. The tanks are also subjected to visual inspection. Digital cameras record the interior surface of

  3. Overview of Hanford Single Shell Tank (SST) Structural Integrity

    International Nuclear Information System (INIS)

    Rast, Richard S.; Washenfelder, Dennis J.; Johnson, Jeremy M.

    2013-01-01

    To improve the understanding of the single-shell tanks (SSTs) integrity, Washington River Protection Solutions, LLC (WRPS), the USDOE Hanford Site tank contractor, developed an enhanced Single-Shell Tank Integrity Project (SSTIP) in 2009. An expert panel on SST integrity, consisting of various subject matters experts in industry and academia, was created to provide recommendations supporting the development of the project. This panel developed 33 recommendations in four main areas of interest: structural integrity, liner degradation, leak integrity and prevention, and mitigation of contamination migration, Seventeen of these recommendations were used to develop the basis for the M-45-10-1 Change Package for the Hanford Federal Agreement and Compliance Order, which is also known as the Tri-Party Agreement. The structural integrity of the tanks is a key element in completing the cleanup mission at the Hanford Site. There are eight primary recommendations related to the structural integrity of Hanford Single-Shell Tanks. Six recommendations are being implemented through current and planned activities. The structural integrity of the Hanford is being evaluated through analysis, monitoring, inspection, materials testing, and construction document review. Structural evaluation in the form of analysis is performed using modern finite element models generated in ANSYS. The analyses consider in-situ, thermal, operating loads and natural phenomena such as earthquakes. Structural analysis of 108 of 149 Hanford Single-Shell Tanks has concluded that the tanks are structurally sound and meet current industry standards. Analysis of the remaining Hanford Single-Shell Tanks is scheduled for FY2014. Hanford Single-Shell Tanks are monitored through a dome deflection program. The program looks for deflections of the tank dome greater than 1/4 inch. No such deflections have been recorded. The tanks are also subjected to visual inspection. Digital cameras record the interior surface of

  4. Radar attenuation in Europa's ice shell: Obstacles and opportunities for constraining the shell thickness and its thermal structure

    Science.gov (United States)

    Kalousová, Klára; Schroeder, Dustin M.; Soderlund, Krista M.

    2017-03-01

    Young surface and possible recent endogenic activity make Europa one of the most exciting solar system bodies and a primary target for spacecraft exploration. Future Europa missions are expected to carry ice-penetrating radar instruments designed to investigate its subsurface thermophysical structure. Several authors have addressed the radar sounders' performance at icy moons, often ignoring the complex structure of a realistic ice shell. Here we explore the variation in two-way radar attenuation for a variety of potential thermal structures of Europa's shell (determined by reference viscosity, activation energy, tidal heating, surface temperature, and shell thickness) as well as for low and high loss temperature-dependent attenuation model. We found that (i) for all investigated ice shell thicknesses (5-30 km), the radar sounder will penetrate between 15% and 100% of the total thickness, (ii) the maximum penetration depth varies laterally, with deepest penetration possible through cold downwellings, (iii) direct ocean detection might be possible for shells of up to 15 km thick if the signal travels through cold downwelling ice or the shell is conductive, (iv) even if the ice/ocean interface is not directly detected, penetration through most of the shell could constrain the deep shell structure through returns from deep non-ocean interfaces or the loss of signal itself, and (v) for all plausible ice shells, the two-way attenuation to the eutectic point is ≲30 dB which shows a robust potential for longitudinal investigation of the ice shell's shallow thermophysical structure.

  5. Faceted shell structure in grain boundary diffusion-processed sintered Nd–Fe–B magnets

    Energy Technology Data Exchange (ETDEWEB)

    Seelam, U.M.R.; Ohkubo, T.; Abe, T.; Hirosawa, S.; Hono, K., E-mail: kazuhiro.hono@nims.go.jp

    2014-12-25

    Graphical abstract: The grain boundary diffusion process (GBDP) using a heavy rare earth elements (HRE) such as Dy and Tb is known as an effective method to enhance the coercivity of Nd–Fe–B sintered magnets without reducing remanence. This process has been industrially implemented to manufacture Nd–Fe–B based sintered magnets with high coercivity and high remanence. In this process, Dy is considered to diffuse through grain boundaries (GBs) to form (Nd{sub 1−x}Dy{sub x}){sub 2}Fe{sub 14}B shells surrounding the Nd{sub 2}Fe{sub 14}B grains and the higher anisotropy field of the Dy-rich shell is considered to suppress the nucleation of reverse domains at low magnetic field. Although there are several investigations on the microstructure of HRE GBDP Nd–Fe–B magnets, no paper addressed the origin of the asymmetric formation of HRE rich shells. Based on detailed analysis of facet planes of core/shell interfaces, we propose a mechanism of the faceted core/shell microstructure formation in the GBDP sintered magnets. We believe that this gives new insights on understanding the coercivity enhancement by the GBDP. - Highlights: • Faceting was observed at the interfaces of cores and shells. • The core/shell interfaces are sharp with an abrupt change in Dy concentration. • Meting occurs at the interfaces of metalic Nd-rich/Nd{sub 2}Fe{sub 14}B phases above 685 °C due to eutectic reaction. • Solidification of Dy-enriched liquid phase from 900 °C can result in the shell formation. - Abstract: Dysprosium enriched shell structure formed by the grain boundary diffusion process (GBDP) of a sintered Nd–Fe–B magnet was characterized by using scanning electron microscopy, electron back-scattered diffraction and transmission electron microscopy. Faceted core–shell interfaces with an abrupt change in Dy concentration suggest the Dy-rich shells are formed by the solidification of the liquid phase during cooling from the GBDP temperature. The Nd-rich phases

  6. Faceted shell structure in grain boundary diffusion-processed sintered Nd–Fe–B magnets

    International Nuclear Information System (INIS)

    Seelam, U.M.R.; Ohkubo, T.; Abe, T.; Hirosawa, S.; Hono, K.

    2014-01-01

    Graphical abstract: The grain boundary diffusion process (GBDP) using a heavy rare earth elements (HRE) such as Dy and Tb is known as an effective method to enhance the coercivity of Nd–Fe–B sintered magnets without reducing remanence. This process has been industrially implemented to manufacture Nd–Fe–B based sintered magnets with high coercivity and high remanence. In this process, Dy is considered to diffuse through grain boundaries (GBs) to form (Nd 1−x Dy x ) 2 Fe 14 B shells surrounding the Nd 2 Fe 14 B grains and the higher anisotropy field of the Dy-rich shell is considered to suppress the nucleation of reverse domains at low magnetic field. Although there are several investigations on the microstructure of HRE GBDP Nd–Fe–B magnets, no paper addressed the origin of the asymmetric formation of HRE rich shells. Based on detailed analysis of facet planes of core/shell interfaces, we propose a mechanism of the faceted core/shell microstructure formation in the GBDP sintered magnets. We believe that this gives new insights on understanding the coercivity enhancement by the GBDP. - Highlights: • Faceting was observed at the interfaces of cores and shells. • The core/shell interfaces are sharp with an abrupt change in Dy concentration. • Meting occurs at the interfaces of metalic Nd-rich/Nd 2 Fe 14 B phases above 685 °C due to eutectic reaction. • Solidification of Dy-enriched liquid phase from 900 °C can result in the shell formation. - Abstract: Dysprosium enriched shell structure formed by the grain boundary diffusion process (GBDP) of a sintered Nd–Fe–B magnet was characterized by using scanning electron microscopy, electron back-scattered diffraction and transmission electron microscopy. Faceted core–shell interfaces with an abrupt change in Dy concentration suggest the Dy-rich shells are formed by the solidification of the liquid phase during cooling from the GBDP temperature. The Nd-rich phases are almost free from Dy, and

  7. Investigation of stresses in facetted glass shell structures

    DEFF Research Database (Denmark)

    Bagger, Anne; Jönsson, Jeppe; Wester, Ture

    2007-01-01

    by in-plane forces in the facets and the transfer of distributed in-plane forces across the joints. It is described how these facets work structurally, specifically how bending moments develop and cause possible stress concentrations in the corners, which are subjected to uplift. Apart from local...... bending moments from distributed load, other types of bending moments are likely to occur, especially if the shell has areas of low stiffness, for example along a free edge. A facetted shell structure has been modelled in a finite element program, and the resulting stresses are presented and discussed....

  8. Accounting of inter-electron correlations in the model of mobile electron shells

    International Nuclear Information System (INIS)

    Panov, Yu.D.; Moskvin, A.S.

    2000-01-01

    One studied the basic peculiar features of the model for mobile electron shells for multielectron atom or cluster. One offered a variation technique to take account of the electron correlations where the coordinates of the centre of single-particle atomic orbital served as variation parameters. It enables to interpret dramatically variation of electron density distribution under anisotropic external effect in terms of the limited initial basis. One studied specific correlated states that might make correlation contribution into the orbital current. Paper presents generalization of the typical MO-LCAO pattern with the limited set of single particle functions enabling to take account of additional multipole-multipole interactions in the cluster [ru

  9. Fast electrons from multi-electron dynamics in xenon clusters induced by inner-shell ionization

    International Nuclear Information System (INIS)

    Bostedt, Christoph; Thomas, Heiko; Hoener, Matthias; Moeller, Thomas; Saalmann, Ulf; Georgescu, Ionut; Gnodtke, Christian; Rost, Jan-Michael

    2010-01-01

    Fast electrons emitted from xenon clusters in strong femtosecond 90 eV pulses have been measured at the Free-electron Laser in Hamburg (FLASH). Energy absorption occurs mainly through atomic inner-shell photo-ionization. Photo-electrons are trapped in the strong Coulomb potential of the cluster ions and form a non-equilibrium plasma with supra-atomic density. Its equilibration through multiple energy-exchanging collisions within the entire cluster volume produces electrons with energies well beyond the dominant emission line of atomic xenon. Here, in contrast to traditional low-frequency laser plasma heating, the plasma gains energy from electrons delivered through massive single-photon excitation from bound states. Electron emission induced by thermalization of a non-equilibrium plasma is expected to be a general phenomenon occurring for strong atomic x-ray absorption in extended systems.

  10. Structural qualification of the multifunctional instrument tree for installation in double-shell and 100-series single-shell tanks

    International Nuclear Information System (INIS)

    Strohlow, J.P.

    1995-12-01

    This document provides the technical basis and methodology for qualifying the multifunctional instrument tree (MIT) structure for installation in double-shell and 100-series single-shell tanks. Structural qualification for MIT installations in specific tanks are also contained in this document

  11. Magnetic monopole interactions: shell structure of meson and baryon states

    International Nuclear Information System (INIS)

    Akers, D.

    1986-01-01

    It is suggested that a low-mass magnetic monopole of Dirac charge g = (137/2)e may be interacting with a c-quark's magnetic dipole moment to produce Zeeman splitting of meson states. The mass M 0 = 2397 MeV of the monopole is in contrast to the 10 16 -GeV monopoles of grand unification theories (GUT). It is shown that shell structure of energy E/sub n/ = M 0 + 1/4nM 0 ... exists for meson states. The presence of symmetric meson states leads to the identification of the shell structure. The possible existence of the 2397-MeV magnetic monopole is shown to quantize quark masses in agreement with calculations of quantum chromodynamics (QCD). From the shell structure of meson states, the existence of two new mesons is predicted: eta(1814 +/- 50 MeV) with I/sup G/(J/sup PC/) = 0 + (0 -+ ) and eta/sub c/ (3907 +/- 100 MeV) with J/sup PC/ = 0 -+ . The presence of shell structure for baryon states is shown

  12. Electronic structure of silicene

    International Nuclear Information System (INIS)

    Voon, L. C. Lew Yan

    2015-01-01

    In this topical review, we discuss the electronic structure of free-standing silicene by comparing results obtained using different theoretical methods. Silicene is a single atomic layer of silicon similar to graphene. The interest in silicene is the same as for graphene, in being two-dimensional and possessing a Dirac cone. One advantage of silicene is due to its compatibility with current silicon electronics. Both empirical and first-principles techniques have been used to study the electronic properties of silicene. We will provide a brief overview of the parameter space for first-principles calculations. However, since the theory is standard, no extensive discussion will be included. Instead, we will emphasize what empirical methods can provide to such investigations and the current state of these theories. Finally, we will review the properties computed using both types of theories for free-standing silicene, with emphasis on areas where we have contributed. Comparisons to graphene is provided throughout. (topical review)

  13. Cu cluster shell structure at elevated temperatures

    DEFF Research Database (Denmark)

    Christensen, Ole Bøssing; Jacobsen, Karsten Wedel; Nørskov, Jens Kehlet

    1991-01-01

    Equilibrium structures of small (3–29)-atom Cu clusters are determined by simulated annealing, and finite-temperature ensembles are simulated by Monte Carlo techniques using the effective-medium theory for the energy calculation. Clusters with 8, 18, and 20 atoms are found to be particularly stable....... The equilibrium geometrical structures are determined and found to be determined by a Jahn-Teller distortion, which is found to affect the geometry also at high temperatures. The ‘‘magic’’ clusters retain their large stability even at elevated temperatures....

  14. Electronic band structure

    International Nuclear Information System (INIS)

    Grosso, G.

    1986-01-01

    The aim of this chapter is to present, in detail, some theoretical methods used to calculate electronic band structures in crystals. The basic strategies employed to attack the problem of electronic-structure calculations are presented. Successive sections present the basic formulations of the tight-binding, orthogonalized-plane-wave, Green'sfunction, and pseudopotential methods with a discussion of their application to perfect solids. Exemplifications in the case of a few selected problems provide further insight by the author into the physical aspects of the different methods and are a guide to the use of their mathematical techniques. A discussion is offered of completely a priori Hartree-Fock calculations and attempts to extend them. Special aspects of the different methods are also discussed in light of recently published related work

  15. Inner shell excitation in atoms and molecules by high resolution electron impact

    International Nuclear Information System (INIS)

    King, G.C.

    1986-01-01

    In this work an inner-shell spin-forbidden transition in N 2 and a parity-forbidden transition in Ar were studied. These transitions were observed by using incident electron energies as low as 1.15 times the excitation energy of the inner-shell states. (Auth.)

  16. On buckling of double-shell-stiffened cylindrical steel structures

    International Nuclear Information System (INIS)

    Chen, S.J.; Chiu, K.D.; Odar, E.

    1981-01-01

    Buckling analysis methods and acceptance criteria for single shells of various configurations are well documented and adequately covered by many codes. There are, however, no guidelines or criteria for large Double-Shell-Stiffened (DSS) structures, which have been used recently in nuclear power plant applications. The existing codes for buckling analysis cannot be directly utilized because of the uniqueness of structural configuration and complexity of loading. This paper discusses a method for determining the critical buckling loads for this type of structure under a multitude load and suggests buckling criteria for the design of DSS structures. The method commonly used to determine the critical buckling loads for a single shell with or without stiffeners applies reduction factors to the theoretical results. The capacity reduction factors, which are often obtained from experimental results, include plasticity corrections and account for the difference between actual and theoretical buckling loads resulting from the effects of imperfections and nonlinearities. The interaction formulas derived from experimental results can be used to compute the interaction effects of three stress components. This paper extends these concepts and discusses their applicability to a DSS cylindrical structure. (orig./HP)

  17. Three-dimensional fabrication and characterisation of core-shell nano-columns using electron beam patterning of Ge-doped SiO2

    DEFF Research Database (Denmark)

    Gontard, Lionel C.; Jinschek, Joerg R.; Ou, Haiyan

    2012-01-01

    electron tomography. The results show that transformations in insulators that have been subjected to intense irradiation using charged particles can be studied directly in three dimensions. The fabricated structures include core-shell nano-columns, sputtered regions, voids, and clusters. (C) 2012 American......A focused electron beam in a scanning transmission electron microscope (STEM) is used to create arrays of core-shell structures in a specimen of amorphous SiO2 doped with Ge. The same electron microscope is then used to measure the changes that occurred in the specimen in three dimensions using...

  18. Electron spin resonance dating of shells from the sambaqui (shell mound) Capelinha, Sao Paulo, Brazil

    International Nuclear Information System (INIS)

    Kinoshita, A.; Figuty, L.; Baffa, O.

    2006-01-01

    Capelinha is a fluvial sambaqui (Brazilian Shell Mound) located in the Ribeira Valley in the State of Sao Paulo that is being studied. It is one of the oldest sambaquis located along a river dated so far in this region. The use of ESR to date other shells stimulated our group to apply this method to the Capelinha site. Shells from land snails (Megalobulimus sp.) obtained in two levels of excavations were analyzed; one of them was in contact with a skeleton that was dated by C-14. The archaeological doses obtained were (8.05±0.07) Gy and (9.50±0.03) Gy. Since the last site was previously dated by C-14 (Beta -Analytics, Beta 153988) giving: 8860 +/- 60 years BP (conventional age) and 10180 to 9710 years BP (calibrated age), the archaeological dose found for this shell was used to determine the local rate of (0.93 to 0.98) mGy/year, that aggress with other surveys done in the region. Using this dose rate the age of the second shell was found to be 8.14 to 8.73 ky BP that agrees with the stratigraphy of the site. (author)

  19. Shell structure and orbit bifurcations in finite fermion systems

    Science.gov (United States)

    Magner, A. G.; Yatsyshyn, I. S.; Arita, K.; Brack, M.

    2011-10-01

    We first give an overview of the shell-correction method which was developed by V.M. Strutinsky as a practicable and efficient approximation to the general self-consistent theory of finite fermion systems suggested by A.B. Migdal and collaborators. Then we present in more detail a semiclassical theory of shell effects, also developed by Strutinsky following original ideas of M.C. Gutzwiller. We emphasize, in particular, the influence of orbit bifurcations on shell structure. We first give a short overview of semiclassical trace formulae, which connect the shell oscillations of a quantum system with a sum over periodic orbits of the corresponding classical system, in what is usually called the "periodic orbit theory". We then present a case study in which the gross features of a typical double-humped nuclear fission barrier, including the effects of mass asymmetry, can be obtained in terms of the shortest periodic orbits of a cavity model with realistic deformations relevant for nuclear fission. Next we investigate shell structures in a spheroidal cavity model which is integrable and allows for far-going analytical computation. We show, in particular, how period-doubling bifurcations are closely connected to the existence of the so-called "superdeformed" energy minimum which corresponds to the fission isomer of actinide nuclei. Finally, we present a general class of radial power-law potentials which approximate well the shape of a Woods-Saxon potential in the bound region, give analytical trace formulae for it and discuss various limits (including the harmonic oscillator and the spherical box potentials).

  20. Material Distribution Optimization for the Shell Aircraft Composite Structure

    Science.gov (United States)

    Shevtsov, S.; Zhilyaev, I.; Oganesyan, P.; Axenov, V.

    2016-09-01

    One of the main goal in aircraft structures designing isweight decreasing and stiffness increasing. Composite structures recently became popular in aircraft because of their mechanical properties and wide range of optimization possibilities.Weight distribution and lay-up are keys to creating lightweight stiff strictures. In this paperwe discuss optimization of specific structure that undergoes the non-uniform air pressure at the different flight conditions and reduce a level of noise caused by the airflowinduced vibrations at the constrained weight of the part. Initial model was created with CAD tool Siemens NX, finite element analysis and post processing were performed with COMSOL Multiphysicsr and MATLABr. Numerical solutions of the Reynolds averaged Navier-Stokes (RANS) equations supplemented by k-w turbulence model provide the spatial distributions of air pressure applied to the shell surface. At the formulation of optimization problem the global strain energy calculated within the optimized shell was assumed as the objective. Wall thickness has been changed using parametric approach by an initiation of auxiliary sphere with varied radius and coordinates of the center, which were the design variables. To avoid a local stress concentration, wall thickness increment was defined as smooth function on the shell surface dependent of auxiliary sphere position and size. Our study consists of multiple steps: CAD/CAE transformation of the model, determining wind pressure for different flow angles, optimizing wall thickness distribution for specific flow angles, designing a lay-up for optimal material distribution. The studied structure was improved in terms of maximum and average strain energy at the constrained expense ofweight growth. Developed methods and tools can be applied to wide range of shell-like structures made of multilayered quasi-isotropic laminates.

  1. Controllable dielectric and electrical performance of polymer composites with novel core/shell-structured conductive particles through biomimetic method

    International Nuclear Information System (INIS)

    Yang, Dan; Tian, Ming; Wang, Wencai; Li, Dongdong; Li, Runyuan; Liu, Haoliang; Zhang, Liqun

    2013-01-01

    Highlights: ► Conductive core/shell-structured particles were synthesized by biomimetic method. ► These particles with silica/poly(dopamine)/silver core and poly(dopamine) shell. ► Dielectric composites were prepared with resulted particles and silicone elastomer. ► The dielectric properties of the composites can be controlled by shell thickness. ► This biomimetic method is simple, nontoxic, efficient and easy to control. - Abstract: Novel silica/poly(dopamine)/silver (from inner to outer) (denoted as SiO 2 /PDA/Ag) conductive micro-particles were first synthesized by biomimetic poly(dopamine) coating. These micro-particles were then coated with a poly(dopamine) layer to form core/shell-structured particles, with silica/poly(dopamine)/silver core and poly(dopamine) shell (denoted as SiO 2 /PDA/Ag/PDA). This multilayer core/shell micro-particles were confirmed by scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and transmission electron microscope. Polymer composites were then prepared by mechanical blending of poly(dimethyl siloxane) and the core/shell-structured particles. It was found that the silver layer and the poly(dopamine) shell had good adhesion with substrate and they kept intact even under violent shearing stress during mechanical mixing. The effect of the thickness of outermost poly(dopamine) shell as well as the loading amount of this filler on the dielectric and electrical properties of the composites was further studied. The results showed that the dielectric constant, dielectric loss, and conductivity of the composites decreased with increasing shell thickness (10–53 nm) at the same loading level. And the maximal dielectric constant of composites was achieved in the composites filled with SiO 2 /PDA/Ag/PDA (with 10–15 nm PDA shell) particles, which was much larger than that of the composite filled with SiO 2 /PDA/Ag particles without insulative PDA shell. At the same time, the composites can change

  2. Structural responses to plasma disruptions in toroidal shells

    International Nuclear Information System (INIS)

    Tillack, M.S.; Kazimi, M.S.; Lidsky, L.M.

    1985-01-01

    The induced pressures, stresses and strains in unrestrained axisymmetric toroidal shells are studied to scope the behavior of tokamak first walls during plasma disruptions. The modeling includes a circuit analog representation of the shell to solve for induced currents and pressures, and a separate quasi-static 1-D finite element solution for the mechanical response. This work demonstrates that the stresses in tokamkak first walls due to plasma disruption may be large, but to first order will not cause failure in the bulk structure. However, stress concentrations at structural supports and discontinuities together with resonant effects can result in large enhancements of the stresses, which could contribute to plastic deformation or failure when added to the already large steady state thermal and pressure loading of the first wall

  3. The electronic structures of solids

    CERN Document Server

    Coles, B R

    2013-01-01

    The Electronic Structures of Solids aims to provide students of solid state physics with the essential concepts they will need in considering properties of solids that depend on their electronic structures and idea of the electronic character of particular materials and groups of materials. The book first discusses the electronic structure of atoms, including hydrogen atom and many-electron atom. The text also underscores bonding between atoms and electrons in metals. Discussions focus on bonding energies and structures in the solid elements, eigenstates of free-electron gas, and electrical co

  4. Dynamic model of open shell structures buried in poroelastic soils

    Science.gov (United States)

    Bordón, J. D. R.; Aznárez, J. J.; Maeso, O.

    2017-08-01

    This paper is concerned with a three-dimensional time harmonic model of open shell structures buried in poroelastic soils. It combines the dual boundary element method (DBEM) for treating the soil and shell finite elements for modelling the structure, leading to a simple and efficient representation of buried open shell structures. A new fully regularised hypersingular boundary integral equation (HBIE) has been developed to this aim, which is then used to build the pair of dual BIEs necessary to formulate the DBEM for Biot poroelasticity. The new regularised HBIE is validated against a problem with analytical solution. The model is used in a wave diffraction problem in order to show its effectiveness. It offers excellent agreement for length to thickness ratios greater than 10, and relatively coarse meshes. The model is also applied to the calculation of impedances of bucket foundations. It is found that all impedances except the torsional one depend considerably on hydraulic conductivity within the typical frequency range of interest of offshore wind turbines.

  5. Explosion-Induced Implosions of Cylindrical Shell Structures

    Science.gov (United States)

    Ikeda, C. M.; Duncan, J. H.

    2010-11-01

    An experimental study of the explosion-induced implosion of cylindrical shell structures in a high-pressure water environment was performed. The shell structures are filled with air at atmospheric pressure and are placed in a large water-filled pressure vessel. The vessel is then pressurized to various levels P∞=αPc, where Pc is the natural implosion pressure of the model and α is a factor that ranges from 0.1 to 0.9. An explosive is then set off at various standoff distances, d, from the model center line, where d varies from R to 10R and R is the maximum radius of the explosion bubble. High-speed photography (27,000 fps) was used to observe the explosion and resulting shell structure implosion. High-frequency underwater blast sensors recorded dynamic pressure waves at 6 positions. The cylindrical models were made from aluminum (diameter D = 39.1 mm, wall thickness t = 0.89 mm, length L = 240 mm) and brass (D = 16.7 mm, t = 0.36 mm, L=152 mm) tubes. The pressure records are interpreted in light of the high-speed movies. It is found that the implosion is induced by two mechanisms: the shockwave generated by the explosion and the jet formed during the explosion-bubble collapse. Whether an implosion is caused by the shockwave or the jet depends on the maximum bubble diameter and the standoff distance.

  6. Electron spectroscopy studies of argon K-shell excitation and vacancy cascades

    International Nuclear Information System (INIS)

    Southworth, S.H.; MacDonald, M.A.; LeBrun, T.; Azuma, Y.; Cooper, J.W.

    1995-01-01

    Electron spectroscopy combined with tunable synchrotron radiation has been used for studies of Ar K-shell excitation and vacancy decay processes. In addition, electrons and fluorescent X-rays have been recorded in coincidence to select subsets of the ejected electron spectra. Examples are presented for Ar 1s photoelectrons and KLL and LMM Auger spectra

  7. Dynamics of solid inner-shell electrons in collisions with bare and dressed swift ions

    International Nuclear Information System (INIS)

    Montanari, C.C.; Miraglia, J. E.; Arista, N.R.

    2002-01-01

    We analyze the dynamical interactions of swift heavy projectiles and solid inner-shell electrons. The dielectric formalism employed to deal with the free-electron gas is extended to account for the core electrons, by using the local plasma approximation. Results for stopping power, energy straggling, and inner-shell ionization in collisions of bare ions with metals are displayed, showing very good accord with the experimental data. Simultaneous excitations of projectile and target electrons are also analyzed. In the high-energy range we find a similar contribution of target core and valence electrons to the probability of projectile-electron loss. The problem of no excitation threshold within the local plasma approximation and the possibility of collective excitations of the shells are discussed

  8. TiN/VN composites with core/shell structure for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Shanmu; Chen, Xiao [Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, Qingdao 266101 (China); Gu, Lin [WPI Advanced Institute for Materials Research, Tohoku University, Sendai 9808577 (Japan); Zhou, Xinhong [Qingdao University of Science and Technology, Qingdao 266101 (China); Wang, Haibo; Liu, Zhihong; Han, Pengxian; Yao, Jianhua; Wang, Li [Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, Qingdao 266101 (China); Cui, Guanglei, E-mail: cuigl@qibebt.ac.cn [Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, Qingdao 266101 (China); Chen, Liquan [Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, Qingdao 266101 (China); Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China)

    2011-06-15

    Research highlights: {yields} Vanadium and titanium nitride nanocomposite with core-shell structure was prepared. {yields} TiN/VN composites with different V:Ti molar ratios were obtained. {yields} TiN/VN composites can provide promising electronic conductivity and favorable capacity storage. -- Abstract: TiN/VN core-shell composites are prepared by a two-step strategy involving coating of commercial TiN nanoparticles with V{sub 2}O{sub 5}.nH{sub 2}O sols followed by ammonia reduction. The highest specific capacitance of 170 F g{sup -1} is obtained when scanned at 2 mV s{sup -1} and a promising rate capacity performance is maintained at higher voltage sweep rates. These results indicate that these composites with good electronic conductivity can deliver a favorable capacity performance.

  9. Shell structure of potassium isotopes deduced from their magnetic moments

    CERN Document Server

    Papuga, J.; Kreim, K; Barbieri, C; Blaum, K; De Rydt, M; Duguet, T; Garcia Ruiz, R F; Heylen, H; Kowalska, M; Neugart, R; Neyens, G; Nortershauser, W; Rajabali, M M; Sanchez, R; Smirnova, N; Soma, V; Yordanov, D T

    2014-09-29

    $\\textbf{Background:}$ Ground-state spins and magnetic moments are sensitive to the nuclear wave function, thus they are powerful probes to study the nuclear structure of isotopes far from stability. \\\\ \\\\ $\\textbf{Purpose:}$ Extend our knowledge about the evolution of the $1/2^+$ and $3/2^+$ states for K isotopes beyond the $N = 28$ shell gap. \\\\ \\\\ $\\textbf{Method:}$ High-resolution collinear laser spectroscopy on bunched atomic beams. \\\\ \\\\ $\\textbf{Results:}$ From measured hyperfine structure spectra of K isotopes, nuclear spins and magnetic moments of the ground states were obtained for isotopes from $N = 19$ up to $N = 32$. In order to draw conclusions about the composition of the wave functions and the occupation of the levels, the experimental data were compared to shell-model calculations using SDPF-NR and SDPF-U effective interactions. In addition, a detailed discussion about the evolution of the gap between proton $1d_{3/2}$ and $2s_{1/2}$ in the shell model and $\\textit{ab initio}$ framework is al...

  10. Understanding valence-shell electron-pair repulsion (VSEPR) theory using origami molecular models

    International Nuclear Information System (INIS)

    Saraswati, Teguh Endah; Saputro, Sulistyo; Ramli, Murni; Praseptiangga, Danar; Khasanah, Nurul; Marwati, Sri

    2017-01-01

    Valence-shell electron-pair repulsion (VSEPR) theory is conventionally used to predict molecular geometry. However, it is difficult to explore the full implications of this theory by simply drawing chemical structures. Here, we introduce origami modelling as a more accessible approach for exploration of the VSEPR theory. Our technique is simple, readily accessible and inexpensive compared with other sophisticated methods such as computer simulation or commercial three-dimensional modelling kits. This method can be implemented in chemistry education at both the high school and university levels. We discuss the example of a simple molecular structure prediction for ammonia (NH 3 ). Using the origami model, both molecular shape and the scientific justification can be visualized easily. This ‘hands-on’ approach to building molecules will help promote understanding of VSEPR theory. (paper)

  11. Understanding valence-shell electron-pair repulsion (VSEPR) theory using origami molecular models

    Science.gov (United States)

    Endah Saraswati, Teguh; Saputro, Sulistyo; Ramli, Murni; Praseptiangga, Danar; Khasanah, Nurul; Marwati, Sri

    2017-01-01

    Valence-shell electron-pair repulsion (VSEPR) theory is conventionally used to predict molecular geometry. However, it is difficult to explore the full implications of this theory by simply drawing chemical structures. Here, we introduce origami modelling as a more accessible approach for exploration of the VSEPR theory. Our technique is simple, readily accessible and inexpensive compared with other sophisticated methods such as computer simulation or commercial three-dimensional modelling kits. This method can be implemented in chemistry education at both the high school and university levels. We discuss the example of a simple molecular structure prediction for ammonia (NH3). Using the origami model, both molecular shape and the scientific justification can be visualized easily. This ‘hands-on’ approach to building molecules will help promote understanding of VSEPR theory.

  12. Role of shell structure in the 2νββ nuclear matrix elements

    International Nuclear Information System (INIS)

    Nakada, H.

    1998-01-01

    Significance of the nuclear shell structure in the ββ nuclear matrix elements is pointed out. The 2νββ processes are mainly mediated by the low-lying 1 + states. The shell structure also gives rise to concentration or fragmentation of the 2νββ components over intermediate states, depending on nuclide. These roles of the shell structure are numerically confirmed by realistic shell model calculations. Some shell structure effects are suggested for 0νββ matrix elements; dominance of low-lying intermediate states and nucleus-dependence of their spin-parities. (orig.)

  13. Response of a shell structure subject to distributed harmonic excitation

    International Nuclear Information System (INIS)

    Cao, Rui; Bolton, J. Stuart

    2016-01-01

    Previously, a coupled, two-dimensional structural-acoustic ring model was constructed to simulate the dynamic and acoustical behavior of pneumatic tires. Analytical forced solutions were obtained and were experimentally verified through laser velocimeter measurement made using automobile tires. However, the two-dimensional ring model is incapable of representing higher order, in-plane modal motion in either the circumferential or axial directions. Therefore, in this paper, a three-dimensional pressurized circular shell model is proposed to study the in-plane shearing motion and the effect of different forcing conditions. Closed form analytical solutions were obtained for both free and forced vibrations of the shell under simply supported boundary conditions. Dispersion relations were calculated and different wave types were identified by their different speeds. Shell surface mobility results under various input distributions were also studied and compared. Spatial Fourier series decompositions were also performed on the spatial mobility results to give the forced dispersion relations, which illustrate clearly the influence of input force spatial distribution. Such a model has practical application in identifying the sources of noise and vibration problems in automotive tires. (paper)

  14. Point-like structure and off-shell dual strings

    International Nuclear Information System (INIS)

    Green, M.B.

    1977-01-01

    It is argued that in a consistent off-shell dual formalism the amplitude for the emission of a scalar off-shell state by a string consists of two components. One of these contains the particle poles in the off-shell leg and the other is intimately related to the insertion of a point-like energy density on the string. As a result, the amplitude for a string to emit a zero momentum scalar state into the vacuum (which may be relevant for spontaneous symmetry breaking) is described by the amplitude for a finite fraction of the energy in the string to collapse to a spatial point at some time (this fraction and its space-time position being integrated over). The off-shell amplitudes have an elegant formulation in terms of a set of 'confined modes' which can be assigned quark flavour quantum numbers to reproduce the Chan-Paton scheme. It is suggested that the dual model be modified by allowing for the coupling of scalar closed strings to the vacuum and the resulting effect on the space-time structure of dual Green functions is described. It is found that even the emission of a single zero-momentum closed string modifies the elastic amplitude in a significant manner, leading to a power-behaved fixed-angle cross section in contrast to the usual exponential decrease of the dual model. This arises from point-like scattering between energy densities accumulating in the colliding strings. The relationship between the fixed angle and Regge limits is discussed. The fixed angle behaviour is found to be the asymptotic limit in momentum transfer of a fixed pole that arises in the Regge limit. (Auth.)

  15. Electronic Structure of Strongly Correlated Materials

    CERN Document Server

    Anisimov, Vladimir

    2010-01-01

    Electronic structure and physical properties of strongly correlated materials containing elements with partially filled 3d, 4d, 4f and 5f electronic shells is analyzed by Dynamical Mean-Field Theory (DMFT). DMFT is the most universal and effective tool used for the theoretical investigation of electronic states with strong correlation effects. In the present book the basics of the method are given and its application to various material classes is shown. The book is aimed at a broad readership: theoretical physicists and experimentalists studying strongly correlated systems. It also serves as a handbook for students and all those who want to be acquainted with fast developing filed of condensed matter physics.

  16. Chemical Structure, Ensemble and Single-Particle Spectroscopy of Thick-Shell InP-ZnSe Quantum Dots.

    Science.gov (United States)

    Reid, Kemar R; McBride, James R; Freymeyer, Nathaniel J; Thal, Lucas B; Rosenthal, Sandra J

    2018-02-14

    Thick-shell (>5 nm) InP-ZnSe colloidal quantum dots (QDs) grown by a continuous-injection shell growth process are reported. The growth of a thick crystalline shell is attributed to the high temperature of the growth process and the relatively low lattice mismatch between the InP core and ZnSe shell. In addition to a narrow ensemble photoluminescence (PL) line-width (∼40 nm), ensemble and single-particle emission dynamics measurements indicate that blinking and Auger recombination are reduced in these heterostructures. More specifically, high single-dot ON-times (>95%) were obtained for the core-shell QDs, and measured ensemble biexciton lifetimes, τ 2x ∼ 540 ps, represent a 7-fold increase compared to InP-ZnS QDs. Further, high-resolution energy dispersive X-ray (EDX) chemical maps directly show for the first time significant incorporation of indium into the shell of the InP-ZnSe QDs. Examination of the atomic structure of the thick-shell QDs by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) reveals structural defects in subpopulations of particles that may mitigate PL efficiencies (∼40% in ensemble), providing insight toward further synthetic refinement. These InP-ZnSe heterostructures represent progress toward fully cadmium-free QDs with superior photophysical properties important in biological labeling and other emission-based technologies.

  17. Structural and magnetic properties of core-shell iron-iron oxide nanoparticles

    DEFF Research Database (Denmark)

    Kuhn, Luise Theil; Bojesen, A.; Timmermann, L.

    2002-01-01

    We present studies of the structural and magnetic properties of core-shell iron-iron oxide nanoparticles. alpha-Fe nanoparticles were fabricated by sputtering and subsequently covered with a protective nanocrystalline oxide shell consisting of either maghaemite (gamma-Fe2O3) or partially oxidized...... magnetite (Fe3O4). We observed that the nanoparticles were stable against further oxidation, and Mossbauer spectroscopy at high applied magnetic fields and low temperatures revealed a stable form of partly oxidized magnetite. The nanocrystalline structure of the oxide shell results in strong canting...... of the spin structure in the oxide shell, which thereby modifies the magnetic properties of the core-shell nanoparticles....

  18. Electron-capture Rates for pf-shell Nuclei in Stellar Environments and Nucleosynthesis

    Science.gov (United States)

    Suzuki, Toshio; Honma, Michio; Mori, Kanji; Famiano, Michael A.; Kajino, Toshitaka; Hidakai, Jun; Otsuka, Takaharu

    Gamow-Teller strengths in pf-shell nuclei obtained by a new shell-model Hamltonian, GXPF1J, are used to evaluate electron-capture rates in pf-shell nuclei at stellar environments. The nuclear weak rates with GXPF1J, which are generally smaller than previous evaluations for proton-rich nuclei, are applied to nucleosynthesis in type Ia supernova explosions. The updated rates are found to lead to less production of neutron-rich nuclei such as 58Ni and 54Cr, thus toward a solution of the problem of over-production of neutron-rich isotopes of iron-group nuclei compared to the solar abundance.

  19. Holographic shell model: Stack data structure inside black holes?

    Science.gov (United States)

    Davidson, Aharon

    2014-03-01

    Rather than tiling the black hole horizon by Planck area patches, we suggest that bits of information inhabit, universally and holographically, the entire black core interior, a bit per a light sheet unit interval of order Planck area difference. The number of distinguishable (tagged by a binary code) configurations, counted within the context of a discrete holographic shell model, is given by the Catalan series. The area entropy formula is recovered, including Cardy's universal logarithmic correction, and the equipartition of mass per degree of freedom is proven. The black hole information storage resembles, in the count procedure, the so-called stack data structure.

  20. Argonne effect - evidence for the shell structure of proton

    International Nuclear Information System (INIS)

    Levintov, I.I.

    1983-01-01

    A strong spin effect in P,P scattering at parallel spin orientation of a target and a projectile and psub(t)sup(2) > or approximately 4(GeV/c) 2 (psub(t) is a transverse momentum of scattered proton) - Argonne effect - is explained by the presence of Fock configuration (qqc anti cq) ip proton which has the structure of p-shell. An analogous effect in the region psub(perpendicular)sup(2) > or approximately 25(GeV/c) 2 associated with the configuration (qqb anti bq) is predicted

  1. Compton scattering of 145 keV gamma rays by K-shell electrons of silver

    Energy Technology Data Exchange (ETDEWEB)

    Acharya, V B; Singh, B; Ghumman, B S [Punjabi Univ., Patiala (India). Dept. of Physics

    1981-01-01

    Differential cross-sections for the incoherent scattering of 145 keV photons from K-shell electrons of silver are measured at scattering angles ranging from 30/sup 0/ to 150/sup 0/ to investigate the effect of electron binding on the scattering process in the low energy region. Measurements are made employing two NaI (Tl) scintillation spectrometers and a slow-fast coincidence circuit of resolving time 30 ns. The experimental results are compared with the available theoretical data. The total K-shell scattering cross-section is also estimated and is about 45% of the free electron cross-section.

  2. Radiative electron capture into the K-, L-, and M-shell of decelerated, hydrogenic Ge projectiles

    International Nuclear Information System (INIS)

    Stoehlker, T.; Kozhuharov, C.; Livingston, A.E.; Mokler, P.H.; Stachura, Z.; Warczak, A.

    1991-12-01

    Radiative Electron Capture (REC) in 4 to 12 MeV/u Ge 31+ →H 2 collisions has been studied using an X-ray/particle coincidence technique. This technique allowed a systematic investigation of K-shell REC as well as a separation of REC into the projectile L- and M-shells. The cross sections are discussed within a general scaling picture based on the reduced projectile velocity. (orig.)

  3. Organic superalkalis with closed-shell structure and aromaticity

    Science.gov (United States)

    Srivastava, Ambrish Kumar

    2018-06-01

    Benzene (C6H6) and polycyclic hydrocarbons such as naphthalene (C10H8), anthracene (C14H10) and coronene (C24H12) are well known aromatic organic compounds. We study the substitution of Li replacing all H-atoms in these hydrocarbons using density functional method. The vertical ionisation energy of such lithiated species, i.e. C6Li6, C10Li8, C14Li10 and C24Li12 ranges 4.24-4.50 eV, which is lower than the ionisation energy (IE) of Li atom. Thus, these species may behave as superalkalis due to their lower IE than alkali metal. However, these lithiated species possess planar and closed-shell structure, unlike typical superalkalis. Furthermore, all Li-substituted species are aromatic although their degree of aromaticity is reduced as compared to corresponding hydrocarbon analogues. We have further explored the structure of C6Li6 as star-like, unlike its inorganic analogue B3N3Li6, which appears as fan-like structure. We have also demonstrated that the interaction of C6Li6 with a superhalogen (such as BF4) is similar to that of a typical superalkali (such as OLi3). This may further suggest that the proposed lithiated species may form a new class of closed-shell organic superalkalis with aromaticity.

  4. Core/Shell Structured Magnetic Nanoparticles for Biological Applications

    International Nuclear Information System (INIS)

    Park, Jeong Chan; Jung, Myung Hwan

    2013-01-01

    Magnetic nanoparticles have been widely used for biomedical applications, such as magnetic resonance imaging (MRI), hyperthermia, drug delivery and cell signaling. The surface modification of the nanomaterials is required for biomedical use to give physiogical stability, surface reactivity and targeting properties. Among many approaches for the surface modification with materials, such as polymers, organic ligands and metals, one of the most attractive ways is using metals. The fabrication of metal-based, monolayer-coated magnetic nanoparticles has been intensively studied. However, the synthesis of metal-capped magnetic nanoparticles with monodispersities and controllable sizes is still challenged. Recently, gold-capped magnetic nanoparticles have been reported to increase stability and to provide biocompatibility. Magnetic nanoparticle with gold coating is an attractive system, which can be stabilized in biological conditions and readily functionalized in biological conditions and readily functionalized through well-established surface modification (Au-S) chemistry. The Au coating offers plasmonic properties to magnetic nanoparticles. This makes the magnetic/Au core/shell combinations interesting for magnetic and optical applications. Herein, the synthesis and characterization of gold capped-magnetic core structured nanomaterials with different gold sources, such as gold acetate and chloroauric acid have been reported. The core/shell nanoparticles were transferred from organic to aqueous solutions for biomedical applications. Magnetic core/shell structured nanoparticles have been prepared and transferred from organic phase to aqueous solutions. The resulting Au-coated magnetic core nanoparticles might be an attractive system for biomedical applications, which are needed both magnetic resonance imaging and optical imaging

  5. The negative temperature coefficient resistivities of Ag2S-Ag core–shell structures

    International Nuclear Information System (INIS)

    Yu, Mingming; Liu, Dongzhi; Li, Wei; Zhou, Xueqin

    2014-01-01

    In this paper, the conductivity of silver nanoparticle films protected by 3-mercaptopropionic acid (Ag/MPA) has been investigated. When the nanoparticles were annealed in air at 200 °C, they converted to stable Ag 2 S-Ag core–shell structures. The mechanism for the formation of the Ag 2 S-Ag core–shell structures along with the compositional changes and the microstructural evolution of the Ag/MPA nanoparticles during the annealing process are discussed. It is proposed that the Ag 2 S-Ag core–shell structure was formed through a solid-state reduction reaction, in which the Ag + ions coming from Ag 2 S were reduced by sulfonate species and sulfur ions. The final Ag 2 S-Ag films display an exponentially decreased resistivity with increasing temperature from 25 to 170 °C. The negative temperature coefficient resistivity of Ag 2 S-Ag films can be adjusted by changing the S/Ag molar ratio used for the synthesis of the Ag/MPA nanoparticles, paving the way for the preparation of negative temperature-coefficient thermistors via printing technology for use in the electronics.

  6. Shell structures and chaos in nuclei and large metallic clusters

    International Nuclear Information System (INIS)

    Heiss, W.D.; University of the Witwatersrand, Johannesburg; Nazmitdinov, R.G.; Radu, S.; University of the Witwatersrand, Johannesburg

    1995-01-01

    A reflection-asymmetric deformed oscillator potential is analyzed from the classical and quantum mechanical point of view. The connection between occurrence of shell structures and classical periodic orbits is studied using the ''removal of resonances method'' in a classical analysis. In this approximation, the effective single particle potential becomes separable and the frequencies of the classical trajectories are easily determined. It turns out that the winding numbers calculated in this way are in good agreement with the ones found from the corresponding quantum mechanical spectrum using the particle number dependence of the fluctuating part of the total energy. When the octupole term is switched on it is found that prolate shapes are stable against chaos and can exhibit shells where spherical and oblate cases become chaotic. An attempt is made to explain this difference in the quantum mechanical context by looking at the distribution of exceptional points which results from the matrix structure of the respective Hamiltonians. In a similar way we analyze the modified Nilsson model and discuss its consequences for metallic clusters. (orig.)

  7. Ultimate load capacity assessment of reinforced concrete shell structures

    International Nuclear Information System (INIS)

    Gupta, Amita; Singh, R.K.; Kushwaha, H.S.; Mahajan, S.C.; Kakodkar, A.

    1993-01-01

    The objective of this study is to develop capability for prediction of ultimate load capacity of reinforced concrete shell structures. The present finite element code ULCA (Ultimate Load Capacity Assessment) adopts a degenerate concept of formulating general isoparametric shell element with a layered approach in the thickness direction. Different failure modes such as crushing, tensile cracking and reinforcement yielding are recognised for various problems. The structure fails by crushing of concrete when the concrete strain/stress reaches the ultimate stress or strain of concrete. Material nonlinearities as a result of tension cracking, tension stiffening between reinforcement and concrete in cracked region and yielding of reinforcement are considered along with geometric nonlinearity. Thus with this code it is possible to predict the pressure at which the first cracking, first through thickness cracking, first yielding of reinforcement occurs. After validating the code with few bench mark problems for different failure modes a reinforced concrete nuclear containment is analysed for its ultimate capacity and the results are matched with the published results. Further the ultimate load capacity of outer containment wall of Narora Atomic Power Station is predicted. It is observed that containment fails in membrane region and has a sufficient margin against design pressure. (author). 9 refs., 56 figs., 3 tabs., 1 appendix with 4 tabs

  8. Electronic structures of elements according to ionization energies.

    Science.gov (United States)

    Zadeh, Dariush H

    2017-11-28

    The electronic structures of elements in the periodic table were analyzed using available experimental ionization energies. Two new parameters were defined to carry out the study. The first parameter-apparent nuclear charge (ANC)-quantified the overall charge of the nucleus and inner electrons observed by an outer electron during the ionization process. This parameter was utilized to define a second parameter, which presented the shielding ability of an electron against the nuclear charge. This second parameter-electron shielding effect (ESE)-provided an insight into the electronic structure of atoms. This article avoids any sort of approximation, interpolation or extrapolation. First experimental ionization energies were used to obtain the two aforementioned parameters. The second parameter (ESE) was then graphed against the electron number of each element, and was used to read the corresponding electronic structure. The ESE showed spikes/peaks at the end of each electronic shell, providing insight into when an electronic shell closes and a new one starts. The electronic structures of elements in the periodic table were mapped using this methodology. These graphs did not show complete agreement with the previously known "Aufbau" filling rule. A new filling rule was suggested based on the present observations. Finally, a new way to organize elements in the periodic table is suggested. Two earlier topics of effective nuclear charge, and shielding factor were also briefly discussed and compared numerically to demonstrate the capability of the new approach.

  9. Multislice theory of fast electron scattering incorporating atomic inner-shell ionization

    International Nuclear Information System (INIS)

    Dwyer, C.

    2005-01-01

    It is demonstrated how atomic inner-shell ionization can be incorporated into a multislice theory of fast electron scattering. The resulting theory therefore accounts for both inelastic scattering due to inner-shell ionization and dynamical elastic scattering. The theory uses a description of the ionization process based on the angular momentum representation for both the initial and final states of the atomic electron. For energy losses near threshold, only a small number of independent states of the ejected atomic electron need to be considered, reducing demands on computing time, and eliminating the need for tabulated inelastic scattering factors. The theory is used to investigate the influence of the collection aperture size on the spatial origin of the silicon K-shell EELS signal generated by a STEM probe. The validity of a so-called local approximation is also considered

  10. The stabilities and electron structures of Al-Mg clusters with 18 and 20 valence electrons

    Science.gov (United States)

    Yang, Huihui; Chen, Hongshan

    2017-07-01

    The spherical jellium model predicts that metal clusters having 18 and 20 valence electrons correspond to the magic numbers and will show specific stabilities. We explore in detail the geometric structures, stabilities and electronic structures of Al-Mg clusters containing 18 and 20 valence electrons by using genetic algorithm combined with density functional theories. The stabilities of the clusters are governed by the electronic configurations and Mg/Al ratios. The clusters with lower Mg/Al ratios are more stable. The molecular orbitals accord with the shell structures predicted by the jellium model but the 2S level interweaves with the 1D levels and the 2S and 1D orbitals form a subgroup. The clusters having 20 valence electrons form closed 1S21P61D102S2 shells and show enhanced stability. The Al-Mg clusters with a valence electron count of 18 do not form closed shells because one 1D orbital is unoccupied. The ionization potential and electron affinity are closely related to the electronic configurations; their values are determined by the subgroups the HOMO or LUMO belong to. Supplementary material in the form of one pdf file available from the Journal web page at http://https://doi.org/10.1140/epjd/e2017-80042-9

  11. The dorsal shell wall structure of Mesozoic ammonoids

    Directory of Open Access Journals (Sweden)

    Gregor Radtke

    2017-03-01

    Full Text Available The study of pristine preserved shells of Mesozoic Ammonoidea shows different types of construction and formation of the dorsal shell wall. We observe three major types: (i The vast majority of Ammonoidea, usually planispirally coiled, has a prismatic reduced dorsal shell wall which consists of an outer organic component (e.g., wrinkle layer, which is the first layer to be formed, and the subsequently formed dorsal inner prismatic layer. The dorsal mantle tissue suppresses the formation of the outer prismatic layer and nacreous layer. With the exception of the outer organic component, secretion of a shell wall is omitted at the aperture. A prismatic reduced dorsal shell wall is always secreted immediately after the hatching during early teleoconch formation. Due to its broad distribution in (planispiral Ammonoidea, the prismatic reduced dorsal shell wall is probably the general state. (ii Some planispirally coiled Ammonoidea have a nacreous reduced dorsal shell wall which consists of three mineralized layers: two prismatic layers (primary and secondary dorsal inner prismatic layer and an enclosed nacreous layer (secondary dorsal nacreous layer. The dorsal shell wall is omitted at the aperture and was secreted in the rear living chamber. Its layers are a continuation of an umbilical shell doubling (reinforcement by additional shell layers that extends towards the ventral crest of the preceding whorl. The nacreous reduced dorsal shell wall is formed in the process of ontogeny following a prismatic reduced dorsal shell wall. (iii Heteromorph and some planispirally coiled taxa secrete a complete dorsal shell wall which forms a continuation of the ventral and lateral shell layers. It is formed during ontogeny following a prismatic reduced dorsal shell wall or a priori. The construction is identical with the ventral and lateral shell wall, including a dorsal nacreous layer. The wide distribution of the ability to form dorsal nacre indicates that it is

  12. Studies in the electronic structure of matter

    International Nuclear Information System (INIS)

    Swarts, C.A.

    1979-01-01

    The results of various theories for the angular distribution of electrons photoemitted from the outermost p-shell of rare gas atoms are compared. The theories compared are the local density theories of Slater (X/sub α/) and of Hohenberg, Kohn and Sham, the pseudopotential method, Hartree-Fock theory as evaluated by Kennedy and Manson, and Amusia's random phase approximation with exchange (RPAE). Extended Huekel theory is applied to GaAs, GaP, and to the nitrogen isoelectronic trap in GaAs and GaP. The computer perfect crystal band structures are found to be in reasonable agreement with those computed with empirical pseudopotentials. Nitrogen impurity levels in GaAs and GaP are calculated using a cluster model. By means of model calculations for an independent electron metal, exact lineshapes are obtained for the photon absorption, emission and photoemission spectra of deep core states. 97 references

  13. Optical and structural investigation of ZnO@ZnS core–shell nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Flores, Efracio Mamani; Raubach, Cristiane W.; Gouvea, Rogério [CCAF, Instituto de Física e Matemática (IFM), Departamento de Física, Universidade Federal de Pelotas, Campus Capão do Leão PO Box 354, CEP: 96010970, Pelotas, RS (Brazil); Longo, Elson [INCTMN-UNESP, Universidade Estadual Paulista, P.O. Box 355, Araraquara 14801-907, SP (Brazil); Cava, Sergio [CCAF, Centro de Desenvolvimento Tecnológico, Universidade Federal de Pelotas, Rua Félix da Cunha 809, Pelotas, RS (Brazil); Moreira, Mário L., E-mail: mlucio3001@gmail.com [CCAF, Instituto de Física e Matemática (IFM), Departamento de Física, Universidade Federal de Pelotas, Campus Capão do Leão PO Box 354, CEP: 96010970, Pelotas, RS (Brazil)

    2016-04-15

    In the present work, are reported the experimental study of ZnO@ZnS core–shell synthesised by a microwave-assisted solvothermal (MAS) method. Some synthesis parameters such as, time, precursor concentration and temperature were fixed. In order to investigate the effect of growing shell on the structural and optical properties, the samples were grown with two different solvent (water or ethylene glycol). The characterizations were performed by X-ray diffraction, absorption spectroscopy in the UV–vis range, scanning electron microscopy, and photoluminescence spectroscopy. The results show that both ZnO and ZnS diffractions are present for all samples, however the crystallinity degree of ZnS shell are too low. The better decorations of ZnS (shell) on the ZnO (core) are obtained for ethylene glycol (EG) solvent, which is verified through FE-SEM images of ZnO@ZnS (EG). On the other hand, non morphological solvent dependence was observed for ZnO multi-wires. Also the luminescent emission for decorated system in water were more intense and leads to form a type-II band alignment for ZnO@ZnS core–shell system. - Highlights: • Obtation of ZnO@ZnS decorated systens using different solvents by MAS methodology. • Growth solvent dependence of hexagonal and cubic phases for ZnS. • Potential application of ZnO@ZnS decorated nanostructures as replacement material for solar cells. • Control over band alignment between ZnO and ZnS.

  14. The creep analysis of shell structures using generalised models

    International Nuclear Information System (INIS)

    Boyle, J.T.; Spence, J.

    1981-01-01

    In this paper a new, more complete estimate of the accuracy of the stationary creep model is given for the general case through the evaluation of exact and approximate energy surfaces. In addition, the stationary model is extended to include more general non-stationary (combined elastic-creep) behaviour and to include the possibility of material deterioration through damage. The resulting models are then compared to existing exact solutions for several shell structures - e.g. a thin pressurised cylinder, a curved pipe in bending and an S-bellows under axial extension with large deflections. In each case very good agreement is obtained. Although requiring similar computing effort, so that the same solution techniques can be utilised, the calculation times are shown to be significantly reduced using the generalised approach. In conclusion, it has been demonstrated that a new simple mechanical model of a thin shell in creep, with or without material deterioration can be constructed; the model is assessed in detail and successfully compared to existing solutions. (orig./HP)

  15. Overview Of Hanford Single Shell Tank (SST) Structural Integrity - 12123

    International Nuclear Information System (INIS)

    Rast, R.S.; Rinker, M.W.; Washenfelder, D.J.; Johnson, J.B.

    2012-01-01

    To improve the understanding of the single-shell tanks (SSTs) integrity, Washington River Protection Solutions, LLC (WRPS), the USDOE Hanford Site tank contractor, developed an enhanced Single-Shell Tank Integrity Project in 2009. An expert panel on SST integrity, consisting of various subject matters experts in industry and academia, was created to provide recommendations supporting the development of the project. This panel developed 33 recommendations in four main areas of interest: structural integrity, liner degradation, leak integrity and prevention, and mitigation of contamination migration. Seventeen of these recommendations were used to develop the basis for the M-45-10-1 Change Package for the Hanford Federal Agreement and Compliance Order, which is also known as the Tri-Party Agreement. The structural integrity of the tanks is a key element in completing the cleanup mission at the Hanford Site. There are eight primary recommendations related to the structural integrity of Hanford SSTs. Six recommendations are being implemented through current and planned activities. The structural integrity of the Hanford SSTs is being evaluated through analysis, monitoring, inspection, materials testing, and construction document review. Structural evaluation in the form of analysis is performed using modern finite element models generated in ANSYS(reg s ign) The analyses consider in-situ, thermal, operating loads and natural phenomena such as earthquakes. Structural analysis of 108 of 149 Hanford SSTs has concluded that the tanks are structurally sound and meet current industry standards. Analyses of the remaining Hanford SSTs are scheduled for FY2013. Hanford SSTs are monitored through a dome deflection program. The program looks for deflections of the tank dome greater than 1/4 inch. No such deflections have been recorded. The tanks are also subjected to visual inspection. Digital cameras record the interior surface of the concrete tank domes, looking for cracks and

  16. OVERVIEW OF HANFORD SINGLE SHELL TANK (SST) STRUCTURAL INTEGRITY - 12123

    Energy Technology Data Exchange (ETDEWEB)

    RAST RS; RINKER MW; WASHENFELDER DJ; JOHNSON JB

    2012-01-25

    To improve the understanding of the single-shell tanks (SSTs) integrity, Washington River Protection Solutions, LLC (WRPS), the USDOE Hanford Site tank contractor, developed an enhanced Single-Shell Tank Integrity Project in 2009. An expert panel on SST integrity, consisting of various subject matters experts in industry and academia, was created to provide recommendations supporting the development of the project. This panel developed 33 recommendations in four main areas of interest: structural integrity, liner degradation, leak integrity and prevention, and mitigation of contamination migration. Seventeen of these recommendations were used to develop the basis for the M-45-10-1 Change Package for the Hanford Federal Agreement and Compliance Order, which is also known as the Tri-Party Agreement. The structural integrity of the tanks is a key element in completing the cleanup mission at the Hanford Site. There are eight primary recommendations related to the structural integrity of Hanford SSTs. Six recommendations are being implemented through current and planned activities. The structural integrity of the Hanford SSTs is being evaluated through analysis, monitoring, inspection, materials testing, and construction document review. Structural evaluation in the form of analysis is performed using modern finite element models generated in ANSYS{reg_sign} The analyses consider in-situ, thermal, operating loads and natural phenomena such as earthquakes. Structural analysis of 108 of 149 Hanford SSTs has concluded that the tanks are structurally sound and meet current industry standards. Analyses of the remaining Hanford SSTs are scheduled for FY2013. Hanford SSTs are monitored through a dome deflection program. The program looks for deflections of the tank dome greater than 1/4 inch. No such deflections have been recorded. The tanks are also subjected to visual inspection. Digital cameras record the interior surface of the concrete tank domes, looking for cracks and

  17. Active constrained layer damping treatments for shell structures: a deep-shell theory, some intuitive results, and an energy analysis

    Science.gov (United States)

    Shen, I. Y.

    1997-02-01

    This paper studies vibration control of a shell structure through use of an active constrained layer (ACL) damping treatment. A deep-shell theory that assumes arbitrary Lamé parameters 0964-1726/6/1/011/img1 and 0964-1726/6/1/011/img2 is first developed. Application of Hamilton's principle leads to the governing Love equations, the charge equation of electrostatics, and the associated boundary conditions. The Love equations and boundary conditions imply that the control action of the ACL for shell treatments consists of two components: free-end boundary actuation and membrane actuation. The free-end boundary actuation is identical to that of beam and plate ACL treatments, while the membrane actuation is unique to shell treatments as a result of the curvatures of the shells. In particular, the membrane actuation may reinforce or counteract the boundary actuation, depending on the location of the ACL treatment. Finally, an energy analysis is developed to determine the proper control law that guarantees the stability of ACL shell treatments. Moreover, the energy analysis results in a simple rule predicting whether or not the membrane actuation reinforces the boundary actuation.

  18. Extended fine structure in the K-shell photoionization spectrum of Br2

    International Nuclear Information System (INIS)

    Dill, D.; Dehmer, J.L.

    1975-01-01

    The multiple-scattering approach to molecular wavefunctions in the electronic continuum has been used recently to elucidate the structure of the shape resonance just above threshold in the K-shell photoionization spectrum of N 2 . A similar calculation for Br 2 has yielded significantly different results, i.e., there is no shape resonance; appearing instead is a single resonance in the discrete spectrum, and the photoionization spectrum is found to oscillate with appreciable amplitude throughout the spectral range investigated, from threshold to 60 Ry

  19. A refined element-based Lagrangian shell element for geometrically nonlinear analysis of shell structures

    Directory of Open Access Journals (Sweden)

    Woo-Young Jung

    2015-04-01

    Full Text Available For the solution of geometrically nonlinear analysis of plates and shells, the formulation of a nonlinear nine-node refined first-order shear deformable element-based Lagrangian shell element is presented. Natural co-ordinate-based higher order transverse shear strains are used in present shell element. Using the assumed natural strain method with proper interpolation functions, the present shell element generates neither membrane nor shear locking behavior even when full integration is used in the formulation. Furthermore, a refined first-order shear deformation theory for thin and thick shells, which results in parabolic through-thickness distribution of the transverse shear strains from the formulation based on the third-order shear deformation theory, is proposed. This formulation eliminates the need for shear correction factors in the first-order theory. To avoid difficulties resulting from large increments of the rotations, a scheme of attached reference system is used for the expression of rotations of shell normal. Numerical examples demonstrate that the present element behaves reasonably satisfactorily either for the linear or for geometrically nonlinear analysis of thin and thick plates and shells with large displacement but small strain. Especially, the nonlinear results of slit annular plates with various loads provided the benchmark to test the accuracy of related numerical solutions.

  20. Studies in the electronic structure of matter

    International Nuclear Information System (INIS)

    Miller, D.L.

    1979-01-01

    KLL Auger transition rates for helium are computed using simple atomic orbital wavefunctions which take into account the difference in average electron--electron repulsion of initial and final states. The results are consistent with transition rates computed by other authors using a variety of many-electron techniques. It is suggested that wavefunctions determined in the manner described provide a useful representation of the autoionizing state within the first Bohr radius. A method for extracting atomic pseudopotentials from photoelectron angular distributions is described and applied photoionization of the outermost p shells of Ar, Kr, and Xe and to the 4d shell of Xe. The pseudopotentials obtained reproduce the data, and also predict accurate cross sections and phase shifts for photoelectron energies up to 100 eV. It is suggested that the pseudopotentials aptly mimic the effects of intrashell electron--electron correlations in the photoionization process. The extended Hueckel theory is applied to the nitrogen trap in GaAs and GaP. Perfect crystal band structures are computed and are shown to be in reasonable agreement with those computed with empirical pseudopotentials. Nitrogen impurity levels in GaAs and GaP are computed using an extended Hueckel cluster model. In each case the model predicts two states within the band gap, in contrast to experiment which detects one impurity state in GaP and none in GaAs. It is suggested that the choice of cluster used unrealistically concentrates states near the conduction band edge on the central atom

  1. Studies in the electronic structure of matter

    International Nuclear Information System (INIS)

    Miller, D.L.

    1979-01-01

    KLL Auger transition rates for helium are computed using simple atomic orbital wavefunctions which take into account the difference in average electron-electron repulsion of initial and final states. The results are consistent with transition rates computed by other authors using a variety of many-electron techniques. It is suggested that wavefunctions determined in the manner described provide a useful representation of the autoionizing state within the first Bohr radius. A method for extracting atomic psuedopotentials from photoelectron angular distributions is described and applied photoionization of the outermost p shells of Ar, Kr, and Xe and to the 4d shell of Xe. The pseudopotentials obtained reproduce the data, and also predict accurate cross sections and phase shifts for photoelectron energies up to 100 eV. It is suggested that the pseudopotentials aptly mimic the effects of intrashell electron-electron correlations in the photoionization process. The extended Hueckel theory is applied to the nitrogen trap in GaAs and GaP. Perfect crystal band structures are computed and are shown to be in reasonable agreement with those computed with empirical psuedopotentials. Nitrogen impurity levles in GaAs and GaP are computed using an extended Hueckel cluster model. In each case the model predicts two states within the band gap, in contrast to experiment which detects one impurity state in GaP and none in GaAs. It is suggested that the choice of cluster used unrealistically concentrates states near the conduction band edge on the central atom

  2. Effects of Drift-Shell Splitting by Chorus Waves on Radiation Belt Electrons

    Science.gov (United States)

    Chan, A. A.; Zheng, L.; O'Brien, T. P., III; Tu, W.; Cunningham, G.; Elkington, S. R.; Albert, J.

    2015-12-01

    Drift shell splitting in the radiation belts breaks all three adiabatic invariants of charged particle motion via pitch angle scattering, and produces new diffusion terms that fully populate the diffusion tensor in the Fokker-Planck equation. Based on the stochastic differential equation method, the Radbelt Electron Model (REM) simulation code allows us to solve such a fully three-dimensional Fokker-Planck equation, and to elucidate the sources and transport mechanisms behind the phase space density variations. REM has been used to perform simulations with an empirical initial phase space density followed by a seed electron injection, with a Tsyganenko 1989 magnetic field model, and with chorus wave and ULF wave diffusion models. Our simulation results show that adding drift shell splitting changes the phase space location of the source to smaller L shells, which typically reduces local electron energization (compared to neglecting drift-shell splitting effects). Simulation results with and without drift-shell splitting effects are compared with Van Allen Probe measurements.

  3. Synthesis, structural, and optical properties of type-II ZnO–ZnS core–shell nanostructure

    Energy Technology Data Exchange (ETDEWEB)

    Sookhakian, M., E-mail: m.sokhakian@gmail.com [Department of Physics, University of Malaya, Kuala Lumpur 50603 (Malaysia); Amin, Y.M. [Department of Physics, University of Malaya, Kuala Lumpur 50603 (Malaysia); Basirun, W.J. [Department of Chemistry, University of Malaya, Kuala Lumpur 50603 (Malaysia); Nanotechnology and Catalysis Research Centre (NanoCat), Institute of Postgraduate Studies, University Malaya, 50603 Kuala Lumpur (Malaysia); Tajabadi, M.T. [Department of Chemistry, University of Malaya, Kuala Lumpur 50603 (Malaysia); Kamarulzaman, N. [Centre for Nanomaterials Research Institute of Science, Level 3 Block C (Old Engineering Building), Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia)

    2014-01-15

    We demonstrate a facile one-step method for the preparation of ZnO–ZnS core–shell type-II nanostructures, pure ZnS quantum dots and pure ZnO nanoparticles with different experimental conditions. Treatment with sodium hydroxide as a capping agent is investigated systematically during the synthesis of ZnS quantum dots (QDs). The thickness of the ZnS shell is controlled by the concentration of the sodium sulphide during the synthesis of ZnO–ZnS core–shell nanostructures. The morphology and structure of samples are verified by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray analysis (EDX). The UV–vis absorption spectra of the pure ZnS QDs exhibit a blue shift in the absorption edge due to the quantum confinement effect. The PL emission spectra of the ZnO–ZnS core–shell nanostructure are compared with the ZnO nanoparticles. The ZnO–ZnS core–shell nanostructures show decrease in the UV and green emissions with the appearance of a blue emission, which are not found in the ZnO nanoparticles. -- Highlights: • It has synthesised ZnO–ZnS core–shell type II in one-step for the first time. • The as-synthesised samples were characterised by using XRD, UV–vis. • The photoluminescence properties of ZnO–ZnS core–shell was compared with ZnO. • The UV and green emission in the PL spectrum of ZnO–ZnS core–shell decreased. • The blue emission in the PL spectrum of ZnO–ZnS core–shell appeared.

  4. Synthesis, structural, and optical properties of type-II ZnO–ZnS core–shell nanostructure

    International Nuclear Information System (INIS)

    Sookhakian, M.; Amin, Y.M.; Basirun, W.J.; Tajabadi, M.T.; Kamarulzaman, N.

    2014-01-01

    We demonstrate a facile one-step method for the preparation of ZnO–ZnS core–shell type-II nanostructures, pure ZnS quantum dots and pure ZnO nanoparticles with different experimental conditions. Treatment with sodium hydroxide as a capping agent is investigated systematically during the synthesis of ZnS quantum dots (QDs). The thickness of the ZnS shell is controlled by the concentration of the sodium sulphide during the synthesis of ZnO–ZnS core–shell nanostructures. The morphology and structure of samples are verified by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray analysis (EDX). The UV–vis absorption spectra of the pure ZnS QDs exhibit a blue shift in the absorption edge due to the quantum confinement effect. The PL emission spectra of the ZnO–ZnS core–shell nanostructure are compared with the ZnO nanoparticles. The ZnO–ZnS core–shell nanostructures show decrease in the UV and green emissions with the appearance of a blue emission, which are not found in the ZnO nanoparticles. -- Highlights: • It has synthesised ZnO–ZnS core–shell type II in one-step for the first time. • The as-synthesised samples were characterised by using XRD, UV–vis. • The photoluminescence properties of ZnO–ZnS core–shell was compared with ZnO. • The UV and green emission in the PL spectrum of ZnO–ZnS core–shell decreased. • The blue emission in the PL spectrum of ZnO–ZnS core–shell appeared

  5. Controlled growth of Ni/NiO core–shell nanoparticles: Structure, morphology and tuning of magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    D’Addato, S., E-mail: sergio.daddato@unimore.it [CNR-NANO, S3, via G. Campi 213/a, Modena (Italy); Dipartimento FIM, Università di Modena e Reggio Emilia, via G. Campi 213/a, Modena (Italy); Spadaro, M.C. [CNR-NANO, S3, via G. Campi 213/a, Modena (Italy); Dipartimento FIM, Università di Modena e Reggio Emilia, via G. Campi 213/a, Modena (Italy); Luches, P. [CNR-NANO, S3, via G. Campi 213/a, Modena (Italy); Grillo, V. [CNR-NANO, S3, via G. Campi 213/a, Modena (Italy); CNR-IMEM, Parco Area delle Scienze 37/A, 43100 Parma (Italy); Frabboni, S.; Valeri, S. [CNR-NANO, S3, via G. Campi 213/a, Modena (Italy); Dipartimento FIM, Università di Modena e Reggio Emilia, via G. Campi 213/a, Modena (Italy); Ferretti, A.M.; Capetti, E.; Ponti, A. [CNR-ISTM, Laboratorio di Nanotecnologie, via G. Fantoli 16/15, 20138 Milano (Italy)

    2014-07-01

    We performed a detailed study of Ni/NiO core–shell nanoparticles (NP) obtained with a gas aggregation source. The NP oxide shells were produced by oxidizing the NP with different procedures: deposition in oxygen atmosphere, post-annealing in air, sequential deposition of (a) first NiO layer, (b) Ni NP and (c) third NiO Layer. X-ray photoelectron spectroscopy from Ni 2p core-level gave information about the chemical state of Ni in the core and in the oxide shell, while scanning electron microscopy was used for investigation of the NP morphology. High quality scanning transmission electron microscopy in high angle annular dark field mode data demonstrated core–shell structure also for NiO/Ni NP/NiO samples. Field-cooled/zero-field-cooled magnetization curves and field-cooled isothermal hysteresis cycles at T = 5 K were recorded by a SQUID magnetometer. In this way, the relation between magnetic properties and oxide shell structure was assessed, showing the role played by the control of the formation of oxide on the exchange bias and interparticle magnetic interaction.

  6. Controlled growth of Ni/NiO core–shell nanoparticles: Structure, morphology and tuning of magnetic properties

    International Nuclear Information System (INIS)

    D’Addato, S.; Spadaro, M.C.; Luches, P.; Grillo, V.; Frabboni, S.; Valeri, S.; Ferretti, A.M.; Capetti, E.; Ponti, A.

    2014-01-01

    We performed a detailed study of Ni/NiO core–shell nanoparticles (NP) obtained with a gas aggregation source. The NP oxide shells were produced by oxidizing the NP with different procedures: deposition in oxygen atmosphere, post-annealing in air, sequential deposition of (a) first NiO layer, (b) Ni NP and (c) third NiO Layer. X-ray photoelectron spectroscopy from Ni 2p core-level gave information about the chemical state of Ni in the core and in the oxide shell, while scanning electron microscopy was used for investigation of the NP morphology. High quality scanning transmission electron microscopy in high angle annular dark field mode data demonstrated core–shell structure also for NiO/Ni NP/NiO samples. Field-cooled/zero-field-cooled magnetization curves and field-cooled isothermal hysteresis cycles at T = 5 K were recorded by a SQUID magnetometer. In this way, the relation between magnetic properties and oxide shell structure was assessed, showing the role played by the control of the formation of oxide on the exchange bias and interparticle magnetic interaction.

  7. Electronic structure of superlattices

    International Nuclear Information System (INIS)

    Altarelli, M.

    1987-01-01

    Calculations of electronic states in semiconductor superlattices are briefly reviewed, with emphasis on the envelope-function method and on comparison with experiments. The energy levels in presence of external magnetic fields are discussed and compared to magneto-optical experiments. (author) [pt

  8. Resonant Electron capture for be-like ions with K- and L- shell excitations

    International Nuclear Information System (INIS)

    Hanafy, H.

    2005-01-01

    Resonant electron capture in electron-ion collisions is known as dielectronic recombination (DR). It was proved that, DR dominants usually over radiative recombination (RR) at high energy. Since 1980's, DR is considered a very important process in thermal plasma. The DR is an effective process in self-cooling and ionization balance as well as plasma modeling. Experimental works are still carried out to understand the trends of DR process. In the present work, DR cross sections are calculated for Be-like ions with K- and L- shell excitations. It is found that, DR cross sections increase as the effective charge (Zeff) increases for both types of excitations. DR rates coefficient in case of L-shell excitation is found to be five times larger than that of K-shell excitation

  9. Contribution of Brazil nut shell fiber and electron-beam irradiation in thermomechanical properties of HDPE

    International Nuclear Information System (INIS)

    Polato, Pamella; Lorusso, Leandro Alex; Souza, Clecia de Moura; Moura, Esperidiana Augusta Barretos de; Chinellato, Anne; Rosa, Ricardo de

    2010-01-01

    In the present work, the influence of electron-beam irradiation on thermo-mechanical properties of HDPE and HDPE/Brazil nut shell fiber composite was investigated. The materials were irradiated at radiation dose 50 kGy using a 1.5 MeV electron beam accelerator, at room temperature in presence of air. The irradiated and non-irradiated samples were submitted to thermo-mechanical tests and the correlation between their properties was discussed. The results showed that the incorporation of Brazil nut shell fiber represented a significant gain (p < 0,05) in tensile strength at break, flexural strength, flexural module, Vicat softening temperature and heat distortion temperature (HDT) properties of the HDPE. In addition, the irradiated HDPE/Brazil nut shell fiber composite presented a significant increase (p < 0.05) in this properties compared with irradiated HDPE. (author)

  10. Core@shell@shell structured carbon-based magnetic ternary nanohybrids: Synthesis and their enhanced microwave absorption properties

    Science.gov (United States)

    Yang, Erqi; Qi, Xiaosi; Xie, Ren; Bai, Zhongchen; Jiang, Yang; Qin, Shuijie; Zhong, Wei; Du, Youwei

    2018-05-01

    High encapsulation efficiency of core@shell@shell structured carbon-based magnetic ternary nanohybrids have been synthesized in high yield by chemical vapor deposition of acetylene directly over octahedral-shaped Fe2O3 nanoparticles. By controlling the pyrolysis temperature, Fe3O4@Fe3C@carbon nanotubes (CNTs) and Fe@Fe3C@CNTs ternary nanohybrids could be selectively produced. The optimal RL values for the as-prepared ternary nanohybrids could reach up to ca. -46.7, -52.7 and -29.5 dB, respectively. The excellent microwave absorption properties of the obtaiend ternary nanohybrids were proved to ascribe to the quarter-wavelength matching model. Moreover, the as-prepared Fe@Fe3C@CNTs ternary nanohybrids displayed remarkably enhanced EM wave absorption capabilities compared to Fe3O4@Fe3C@CNTs due to their excellent dielectric loss abilities, good complementarities between the dielectric loss and the magnetic loss, and high attenuation constant. Generally, this strategy can be extended to explore other categories of core@shell or core@shell@shell structured carbon-based nanohybrids, which is very beneficial to accelerate the advancements of high performance MAMs.

  11. Electronic structure of alloys

    International Nuclear Information System (INIS)

    Ehrenreich, H.; Schwartz, L.M.

    1976-01-01

    The description of electronic properties of binary substitutional alloys within the single particle approximation is reviewed. Emphasis is placed on a didactic exposition of the equilibrium properties of the transport and magnetic properties of such alloys. Topics covered include: multiple scattering theory; the single band alloy; formal extensions of the theory; the alloy potential; realistic model state densities; the s-d model; and the muffin tin model. 43 figures, 3 tables, 151 references

  12. Morphology and oxide shell structure of iron nanoparticles grown by sputter-gas-aggregation

    International Nuclear Information System (INIS)

    Wang, C M; Baer, D R; Amonette, J E; Engelhard, M H; Qiang, Y; Antony, J

    2007-01-01

    The crystal faceting planes and oxide coating structures of core-shell structured iron/iron-oxide nanoparticles synthesized by a sputter-gas-aggregation process were studied using transmission electron microscopy (TEM), electron diffraction and Wulff shape construction. The particles grown by this process and deposited on a support in a room temperature process have been compared with particles grown and deposited at high temperature as reported in the literature. It has been found that the Fe nanoparticles formed at RT are invariantly faceted on the {100} lattice planes and truncated by the {110} planes at different degrees. A substantial fraction of particles are confined only by the 6{100} planes (not truncated by the {110} planes); this contrasts with the Fe particles formed at high temperature (HT) for which a predominance of {110} planes has been reported. Furthermore, at RT no particle was identified to be only confined by the 12{110} planes, which is relatively common for the particles formed at HT. The Fe cubes defined by the 6{100} planes show a characteristic inward relaxation along the and directions and the reason for this behaviour is not fully understood. The oxide shell on the Fe{100} plane maintains an orientation relationship: Fe(001) parallel Fe 3 O 4 (001) and Fe[100] parallel Fe 3 O 4 [110], which is the same as the oxide formed on a bulk Fe(001) through thermal oxidation. Orientation of the oxide that forms on the Fe{110} facets differs from that on Fe{001}: therefore, properties of core-shell structured Fe nanoparticle faceted primarily with one type of lattice plane may be fully different from that faceted with another type of lattice plane

  13. Measurements of integral cross-sections of incoherent interactions of photons with L-shell electrons

    Energy Technology Data Exchange (ETDEWEB)

    Verma, S L; Allawadhi, K L; Sood, B S [Punjabi Univ., Patiala (India). Nuclear Science Labs.

    1983-05-21

    Integral cross-sections of incoherent interactions of 662 and 1250 keV gamma-rays with L-shell electrons of different elements with 74<=Z<=92 have been measured. The experimental results, when interpreted in terms of photoelectric and Compton interaction cross-sections, are found to agree with theory.

  14. Measurement of integral cross-sections of incoherent interactions of photons with K-shell electrons

    Energy Technology Data Exchange (ETDEWEB)

    Verma, S L; Allawadhi, K L; Sood, B S [Punjabi Univ., Patiala (India). Dept. of Physics. Nuclear Science Labs.

    1981-06-01

    Integral cross-sections of incoherent interactions of 145, 279, 662 and 1250 keV gamma-rays with K-shell electrons of thirty-one different elements with 26 <= Z <= 92 have been measured. The results are interpreted in terms of the photoelectric and Compton interactions and are found to agree with theory.

  15. Electronics for Piezoelectric Smart Structures

    Science.gov (United States)

    Warkentin, D. J.; Tani, J.

    1997-01-01

    This paper briefly presents work addressing some of the basic considerations for the electronic components used in smart structures incorporating piezoelectric elements. After general remarks on the application of piezoelectric elements to the problem of structural vibration control, three main topics are described. Work to date on the development of techniques for embedding electronic components within structural parts is presented, followed by a description of the power flow and dissipation requirements of those components. Finally current work on the development of electronic circuits for use in an 'active wall' for acoustic noise is introduced.

  16. Facile Synthesis of Yolk/Core-Shell Structured TS-1@Mesosilica Composites for Enhanced Hydroxylation of Phenol

    KAUST Repository

    Zou, Houbing

    2015-12-14

    © 2015 by the authors. In the current work, we developed a facile synthesis of yolk/core-shell structured TS-1@mesosilica composites and studied their catalytic performances in the hydroxylation of phenol with H2O2 as the oxidant. The core-shell TS-1@mesosilica composites were prepared via a uniform coating process, while the yolk-shell TS-1@mesosilica composite was prepared using a resorcinol-formaldehyde resin (RF) middle-layer as the sacrificial template. The obtained materials were characterized by X-ray diffraction (XRD), N2 sorption, Fourier transform infrared spectoscopy (FT-IR) UV-Visible spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The characterization results showed that these samples possessed highly uniform yolk/core-shell structures, high surface area (560–700 m2 g−1) and hierarchical pore structures from oriented mesochannels to zeolite micropores. Importantly, owing to their unique structural properties, these composites exhibited enhanced activity, and also selectivity in the phenol hydroxylation reaction.

  17. High-performance polyimide nanocomposites with core-shell AgNWs@BN for electronic packagings

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Yongcun; Liu, Feng, E-mail: liufeng@nwpu.edu.cn [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi' an Shaanxi 710072 (China)

    2016-08-22

    The increasing density of electronic devices underscores the need for efficient thermal management. Silver nanowires (AgNWs), as one-dimensional nanostructures, possess a high aspect ratio and intrinsic thermal conductivity. However, high electrical conductivity of AgNWs limits their application for electronic packaging. We synthesized boron nitride-coated silver nanowires (AgNWs@BN) using a flexible and fast method followed by incorporation into synthetic polyimide (PI) for enhanced thermal conductivity and dielectric properties of nanocomposites. The thinner boron nitride intermediate nanolayer on AgNWs not only alleviated the mismatch between AgNWs and PI but also enhanced their interfacial interaction. Hence, the maximum thermal conductivity of an AgNWs@BN/PI composite with a filler loading up to 20% volume was increased to 4.33 W/m K, which is an enhancement by nearly 23.3 times compared with that of the PI matrix. The relative permittivity and dielectric loss were about 9.89 and 0.015 at 1 MHz, respectively. Compared with AgNWs@SiO{sub 2}/PI and Ag@BN/PI composites, boron nitride-coated core-shell structures effectively increased the thermal conductivity and reduced the permittivity of nanocomposites. The relative mechanism was studied and discussed. This study enables the identification of appropriate modifier fillers for polymer matrix nanocomposites.

  18. Double K-shell ionization in electron capture decay

    International Nuclear Information System (INIS)

    Intemann, R.L.

    1985-01-01

    Using a semirelativistic theory previously developed by the author, we have computed the total probability per K-capture event for the ionization of the remaining K electron for a dozen nuclides of interest. Based on hydrogenic wave functions and accurate to relative order (Zα) 2 , the theory takes into account the correlation between the two initial K electrons and permits adjustments for screening. Numerical results exhibiting the effects of screening are presented. A comprehensive comparison of the predictions of this theory, as well as those of other theoretical models, with recent experimental data is also given

  19. Theory of elastic thin shells solid and structural mechanics

    CERN Document Server

    Gol'Denveizer, A L; Dryden, H L

    1961-01-01

    Theory of Elastic Thin Shells discusses the mathematical foundations of shell theory and the approximate methods of solution. The present volume was originally published in Russian in 1953, and remains the only text which formulates as completely as possible the different sets of basic equations and various approximate methods of shell analysis emphasizing asymptotic integration. The book is organized into five parts. Part I presents the general formulation and equations of the theory of shells, which are based on the well-known hypothesis of the preservation of the normal element. Part II is

  20. On the description of electronic final states in the K-shell ionization by protons

    International Nuclear Information System (INIS)

    Aashamar, O.; Kocbach, L.

    1976-06-01

    The choice of free electronic wave functions in the description of K-shell ionization by protons is discussed. The previously known discrepancies between PWBA and SCA results are shown to be entirely due to two different choices of electronic wave functions. Calculations in the SCA framework with Hartree-Fock-Slater wave functions are reported. Some general features of the SCA calculations are discussed. (Auth.)

  1. Shell closures, loosely bound structures, and halos in exotic nuclei

    International Nuclear Information System (INIS)

    Saxena, G.; Singh, D.

    2013-01-01

    Inspired by the recent experiments indicating doubly magic nuclei that lie near the drip-line and encouraged by the success of our relativistic mean-field (RMF) plus state-dependent BCS approach to the description of the ground-state properties of drip-line nuclei, we develop this approach further, across the entire periodic table, to explore magic nuclei, loosely bound structures, and halo formation in exotic nuclei. In our RMF+BCS approach, the single-particle continuum corresponding to the RMF is replaced by a set of discrete positive-energy states for the calculations of pairing energy. Detailed analysis of the single-particle spectrum, pairing energies, and densities of the nuclei predict the unusual proton shell closures at proton numbers Z = 6, 14, 16, 34, and unusual neutron shell closures at neutron numbers N = 6, 14, 16, 34, 40, 70, 112. Further, in several nuclei like the neutron-rich isotopes of Ca, Zr, Mo, etc., the gradual filling of lowlying single-particle resonant state together with weakly bound single-particle states lying close to the continuum threshold helps accommodate more neutrons but with an extremely small increase in the binding energy. This gives rise to the occurrence of loosely bound systems of neutron-rich nuclei with a large neutron-to-proton ratio. In general, the halo-like formation, irrespective of the existence of any resonant state, is seen to be due to the large spatial extension of the wave functions for the weakly bound single-particle states with low orbital angular momentum having very small or no centrifugal barriers.

  2. Shell closures, loosely bound structures, and halos in exotic nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Saxena, G., E-mail: gauravphy@gmail.com [Govt. Women Engineering College, Department of Physics (India); Singh, D. [University of Rajasthan, Department of Physics (India)

    2013-04-15

    Inspired by the recent experiments indicating doubly magic nuclei that lie near the drip-line and encouraged by the success of our relativistic mean-field (RMF) plus state-dependent BCS approach to the description of the ground-state properties of drip-line nuclei, we develop this approach further, across the entire periodic table, to explore magic nuclei, loosely bound structures, and halo formation in exotic nuclei. In our RMF+BCS approach, the single-particle continuum corresponding to the RMF is replaced by a set of discrete positive-energy states for the calculations of pairing energy. Detailed analysis of the single-particle spectrum, pairing energies, and densities of the nuclei predict the unusual proton shell closures at proton numbers Z = 6, 14, 16, 34, and unusual neutron shell closures at neutron numbers N = 6, 14, 16, 34, 40, 70, 112. Further, in several nuclei like the neutron-rich isotopes of Ca, Zr, Mo, etc., the gradual filling of lowlying single-particle resonant state together with weakly bound single-particle states lying close to the continuum threshold helps accommodate more neutrons but with an extremely small increase in the binding energy. This gives rise to the occurrence of loosely bound systems of neutron-rich nuclei with a large neutron-to-proton ratio. In general, the halo-like formation, irrespective of the existence of any resonant state, is seen to be due to the large spatial extension of the wave functions for the weakly bound single-particle states with low orbital angular momentum having very small or no centrifugal barriers.

  3. Angular distribution of Auger electrons due to 3d-shell ionization of krypton

    Science.gov (United States)

    Omidvar, K.

    1977-01-01

    Cross sections for electron impact ionization of krypton due to ejection of a 3rd shell electron have been calculated using screened hydrogenic and Hartree-Slater wave functions for target atom. While the total ionization cross sections in the two approximations are within 10% of each other, the Auger electron angular distribution, related to cross sections for specific magnetic quantum numbers of the 3rd electrons, is widely different in the two approximations. The angular distribution due to Hartree-Slater approximation is in excellent agreement with measurement. The physical reason for the discrepancies in the two approximations is explained.

  4. Angular distribution of Auger electrons due to 3d-shell impact ionization of krypton

    Science.gov (United States)

    Omidvar, K.

    1977-01-01

    Cross sections for electron impact ionization of krypton due to ejection of a 3d-shell electron have been calculated using screened hydrogenic and Hartree-Slater wavefunctions for the target atom. While the total ionization cross sections in the two approximations are within 10% of each other, the Auger electron angular distribution, related to cross sections for specific magnetic quantum numbers of the 3d electrons, are widely different in the two approximations. The angular distribution due to the Hartree-Slater approximation is in excellent agreement with measurement. The physical reason for the discrepancies in the two approximations is explained.

  5. Reduction of the radiating sound of a submerged finite cylindrical shell structure by active vibration control.

    Science.gov (United States)

    Kim, Heung Soo; Sohn, Jung Woo; Jeon, Juncheol; Choi, Seung-Bok

    2013-02-06

    In this work, active vibration control of an underwater cylindrical shell structure was investigated, to suppress structural vibration and structure-borne noise in water. Finite element modeling of the submerged cylindrical shell structure was developed, and experimentally evaluated. Modal reduction was conducted to obtain the reduced system equation for the active feedback control algorithm. Three Macro Fiber Composites (MFCs) were used as actuators and sensors. One MFC was used as an exciter. The optimum control algorithm was designed based on the reduced system equations. The active control performance was then evaluated using the lab scale underwater cylindrical shell structure. Structural vibration and structure-borne noise of the underwater cylindrical shell structure were reduced significantly by activating the optimal controller associated with the MFC actuators. The results provide that active vibration control of the underwater structure is a useful means to reduce structure-borne noise in water.

  6. Reduction of the Radiating Sound of a Submerged Finite Cylindrical Shell Structure by Active Vibration Control

    Directory of Open Access Journals (Sweden)

    Seung-Bok Choi

    2013-02-01

    Full Text Available In this work, active vibration control of an underwater cylindrical shell structure was investigated, to suppress structural vibration and structure-borne noise in water. Finite element modeling of the submerged cylindrical shell structure was developed, and experimentally evaluated. Modal reduction was conducted to obtain the reduced system equation for the active feedback control algorithm. Three Macro Fiber Composites (MFCs were used as actuators and sensors. One MFC was used as an exciter. The optimum control algorithm was designed based on the reduced system equations. The active control performance was then evaluated using the lab scale underwater cylindrical shell structure. Structural vibration and structure-borne noise of the underwater cylindrical shell structure were reduced significantly by activating the optimal controller associated with the MFC actuators. The results provide that active vibration control of the underwater structure is a useful means to reduce structure-borne noise in water.

  7. Restricted open-shell Kohn-Sham theory: N unpaired electrons

    International Nuclear Information System (INIS)

    Schulte, Marius; Frank, Irmgard

    2010-01-01

    Graphical abstract: High-spin or low-spin? The lowest-lying states for different multiplicities of iron complexes are described with a combination of restricted open-shell Kohn-Sham theory and Car-Parrinello molecular dynamics. - Abstract: We present an energy expression for restricted open-shell Kohn-Sham theory for N unpaired electrons. It is shown that it is possible to derive an explicit energy expression for all low-spin multiplets of systems that exhibit neither radial nor cylindrical symmetry. The approach was implemented in the CPMD code and tested for iron complexes.

  8. Atomistic Tight-Binding Theory of Electron-Hole Exchange Interaction in Morphological Evolution of CdSe/ZnS Core/Shell Nanodisk to CdSe/ZnS Core/Shell Nanorod

    Directory of Open Access Journals (Sweden)

    Worasak Sukkabot

    2016-01-01

    Full Text Available Based on the atomistic tight-binding theory (TB and a configuration interaction (CI description, the electron-hole exchange interaction in the morphological transformation of CdSe/ZnS core/shell nanodisk to CdSe/ZnS core/shell nanorod is described with the aim of understanding the impact of the structural shapes on the change of the electron-hole exchange interaction. Normally, the ground hole states confined in typical CdSe/ZnS core/shell nanocrystals are of heavy hole-like character. However, the atomistic tight-binding theory shows that a transition of the ground hole states from heavy hole-like to light hole-like contribution with the increasing aspect ratios of the CdSe/ZnS core/shell nanostructures is recognized. According to the change in the ground-state hole characters, the electron-hole exchange interaction is also significantly altered. To do so, optical band gaps, ground-state electron character, ground-state hole character, oscillation strengths, ground-state coulomb energies, ground-state exchange energies, and dark-bright (DB excitonic splitting (stoke shift are numerically demonstrated. These atomistic computations obviously show the sensitivity with the aspect ratios. Finally, the alteration in the hole character has a prominent effect on dark-bright (DB excitonic splitting.

  9. Electron Spin Resonance Dating of Some Animal Teeth Enamel and Shell Fossils

    International Nuclear Information System (INIS)

    Athabutra, Supakij; Siri-Upathum, Chyagrit

    2007-08-01

    Full text: Electron spin resonance (ESR) dating was conducted for some ungulate tooth enamel samples and shell fossils of the the Tham Lod rock shelter Area I (S23W10) located in Highland Archaeology Project in Pang Mapha District, Mae Hong Son Province, Thailand. Age estimation for wave-induced breaching of the cavity and initial sand deposition (Level 19-29) was 33,200 - 18,700 years and 32,300 years for teeth enamel and the shell fossils of Nodularia scobinata sp. (Carditidae) respectively. ESR spectra showed g-factor g1 (gll, gcenter) = 2.0030 - 2.0036, g2 = 2.0040 - 2.0041 and g3 (g?) = 1.997 - 1.9988 formed by CO2- orthorhombic free radical for teeth enamel and g-factor (gcenter) = 2.0042 + 0.0003 formed by SO3- free radical for fresh shell fossils

  10. Single-quantum annihilation of positrons with shell-bound atomic electrons

    International Nuclear Information System (INIS)

    Palathingal, J.C.; Asoka-Kumar, P.; Lynn, K.G.; Posada, Y.; Wu, X.Y.

    1991-01-01

    The single-quantum annihilation of positrons has been studied experimentally with a positron beam and a thin lead target, at energies 1 MeV and higher. Spectral peaks corresponding to the K, L, and M shells have been resolved and observed distinctly for the first time. The shell ratios L/K and M/K have been determined. An analysis of the L peak has yielded the (LII+LIII)/L ratio. The first measurements of the directional distributions of the annihilation quanta of the three individual electron shells are also reported. The results are in agreement with theory. They also point out the potential for applying the phenomena to the development of a tunable, highly directional gamma-ray source

  11. Effects of electron-beam irradiation on HDPE/Brazil nut shell fiber composite

    International Nuclear Information System (INIS)

    Ferreira, Maiara S.; Sartori, Mariana N.; Oliveira, Rene R.; Moura, Esperidiana A.B.

    2013-01-01

    In recent years, research on the replacement of synthetic fibers by natural fibers as reinforcement in thermoplastic composites has increased dramatically due to the advantages of natural fibers, such as low density, low cost, environmental appeal and recyclability. In the present work, the influence of electron-beam irradiation on mechanical properties of HDPE and HDPE/Brazil Nut Shell (Bertholletia excelsa) fiber compositive was investigated. The HDPE composite reinforced with 5% or 10%, by weight of Brazil nut shell fiber powder with particle sizes equal or smaller than 250 μm were obtained by extrusion, using a twin screw extruder. The materials were irradiated at 200 kGy using a 1.5 MeV electron beam accelerator, at room temperature in presence of air. The irradiated and non-irradiated specimens tests samples were submitted to mechanical and thermo-mechanical tests, scanning electron microscopy (SEM), X-Ray diffraction (XRD) and sol-gel analysis and the correlation between their properties was discussed. The results showed significant changes in HDPE mechanical and thermo-mechanical properties due to Brazil nut shell fibers addition and electron-beam irradiation. The surface of the cryo fractured composite samples irradiated showed important visual changes which suggest a better fiber-matrix interfacial adhesion, due to irradiation treatment. These results showed that it is possible to get interesting property gains by using waste from renewable sources instead of the traditional ones and electron-beam radiation treatment. (author)

  12. Effects of electron-beam irradiation on HDPE/Brazil nut shell fiber composite

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Maiara S.; Sartori, Mariana N.; Oliveira, Rene R.; Moura, Esperidiana A.B., E-mail: maiara.sferreira@gmail.com [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2013-07-01

    In recent years, research on the replacement of synthetic fibers by natural fibers as reinforcement in thermoplastic composites has increased dramatically due to the advantages of natural fibers, such as low density, low cost, environmental appeal and recyclability. In the present work, the influence of electron-beam irradiation on mechanical properties of HDPE and HDPE/Brazil Nut Shell (Bertholletia excelsa) fiber compositive was investigated. The HDPE composite reinforced with 5% or 10%, by weight of Brazil nut shell fiber powder with particle sizes equal or smaller than 250 μm were obtained by extrusion, using a twin screw extruder. The materials were irradiated at 200 kGy using a 1.5 MeV electron beam accelerator, at room temperature in presence of air. The irradiated and non-irradiated specimens tests samples were submitted to mechanical and thermo-mechanical tests, scanning electron microscopy (SEM), X-Ray diffraction (XRD) and sol-gel analysis and the correlation between their properties was discussed. The results showed significant changes in HDPE mechanical and thermo-mechanical properties due to Brazil nut shell fibers addition and electron-beam irradiation. The surface of the cryo fractured composite samples irradiated showed important visual changes which suggest a better fiber-matrix interfacial adhesion, due to irradiation treatment. These results showed that it is possible to get interesting property gains by using waste from renewable sources instead of the traditional ones and electron-beam radiation treatment. (author)

  13. Layered structure in core–shell silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Van Tuan, Pham [Advanced Institute for Science and Technology (AIST) and International Training Institute for Materials Science Hanoi University of Science and Technology, 01 Dai Co Viet Street,Hanoi 10000,Vietnam (Viet Nam); Anh Tuan, Chu; Thanh Thuy, Tran; Binh Nam, Vu [Institute of Materials Science (IMS), Vietnamese Academy of Science and Technology (VAST), 18 Hoang Quoc Viet Street, Hanoi 10000 (Viet Nam); Toan Thang, Pham [Advanced Institute for Science and Technology (AIST) and International Training Institute for Materials Science Hanoi University of Science and Technology, 01 Dai Co Viet Street,Hanoi 10000,Vietnam (Viet Nam); Hong Duong, Pham, E-mail: duongphamhong@yahoo.com [Institute of Materials Science (IMS), Vietnamese Academy of Science and Technology (VAST), 18 Hoang Quoc Viet Street, Hanoi 10000 (Viet Nam); Thanh Huy, Pham, E-mail: huy.phamthanh@hust.edu.vn [Advanced Institute for Science and Technology (AIST) and International Training Institute for Materials Science Hanoi University of Science and Technology, 01 Dai Co Viet Street,Hanoi 10000,Vietnam (Viet Nam)

    2014-10-15

    Silicon nanowires (NWs) with core–shell structures were prepared using the Vapor–Liquid–Solid (VLS) method. The wires have lengths of several hundreds of nanometers and diameters in the range of 30–50 nm. Generally, these wires are too large to exhibit the quantum confinement effect of excitons in Si nanocrystals. However, the photoluminescence (PL) and Raman spectra are similar to those of nanocrystalline silicon embedded in a SiO{sub 2} matrix, in which the recombination of quantum-confined excitons plays an important role. This effect occurs only when the average size of the silicon nanocrystals is smaller than 5 nm. To understand this discrepancy, TEM images of nanowires were obtained and analyzed. The results revealed that the cores of wires have a layered Si/SiO{sub 2} structure, in which the thickness of each layer is much smaller than its diameter. The temperature dependence of the PL intensity was recorded from 11 to 300 K; the result is in good agreement with a model that takes into account the energy splitting between the excitonic singlet and triplet levels. - Highlights: • The cores of the Si NWs have a layered Si/SiO{sub 2} structure. • The Si NWs were formed due to the phase separation of Si and SiO{sub 2} and the partial oxidization by residual oxygen. • Two processes, the reaction of Si and oxygen atoms and the combination between Si atoms, occur simultaneously. • The formation of the layered structures is associated with the self-limiting oxidation phenomenon in Si nanostructures.

  14. Dye-Sensitized Solar Cells Based on TiO_2 Nanotube and Shelled Arrayed Structures

    International Nuclear Information System (INIS)

    Zhang, Jie; Kusumawati, Yuly; Pauporté, Thierry

    2016-01-01

    Anatase TiO_2 nanostructure arrays were synthetized starting from a template made of self-standing ZnO NWs prepared by an electrodeposition technique. By controlling the liquid phase deposition step, the obtained structures could be varied from free-standing nanotube (NT) arrays with controlled morphology to hierarchical spiky radiating core-shell rods. The nanotubes were made of assembled nanocrystals with an average size of 7–8 nm. The structures were investigated as n-type layers in DSSCs. The efficiency was enhanced for the core-shell layer and by starting with longer initial ZnO NW templates. The limitation of the cell efficiency was shown related to the specific surface area and dye loading. The cell functioning was in-depth investigated by electrochemical impedance spectroscopy over a large applied voltage range and compared to a cell based on a nanoparticle TO_2 mesoporous layer. A slow recombination rate was found. The enhancement of electron transport with nanocrystallite size explained the conductivity results. We also found that the prepared structures presented a high charge collection efficiency.

  15. A novel shell-structure cell microcarrier (SSCM) for cell transplantation and bone regeneration medicine.

    Science.gov (United States)

    Su, Kai; Gong, Yihong; Wang, Chunming; Wang, Dong-An

    2011-06-01

    The present study aims to develop a novel open and hollow shell-structure cell microcarrier (SSCM) to improve the anchorage-dependent cell (ADC) loading efficiency, increase the space for cell proliferation and tissue regeneration, and better propel its therapeutic effects. Gelatin particles were prepared with oil/water/oil (o/w/o) technique and modified by an adjustable surface crosslinking technique and subsequent release of uncrosslinked material. Optical microscopy and scanning electron microscopy (SEM) were utilized to observe the morphologies of the microcarriers. Cell loading tests were performed to evaluate the biocompatibilities and effect on osteogenesis of SSCM. SSCMs were successfully fabricated via the surface technique. The shell-structure could allow the cell to attach and grow on both outer and inner surface of sphere and provide adequate space for cell proliferation and extracellular matrix (ECM) secretion. The cell loading rate, proliferation rate and osteogenesis-related gene expressions on the SSCMs were higher than those on the spherical gelatin microcarriers. The outstanding performance of injectable SSCMs endowed with favorable micro-structure, desirable cytocompatibility and enhanced cell affinity makes them as a good choice as cell delivery vehicle for transplanting therapeutic cells towards the scope of tissue regeneration.

  16. Electronic structure of silicon superlattices

    International Nuclear Information System (INIS)

    Krishnamurthy, S.; Moriarty, J.A.

    1984-01-01

    Utilizing a new complex-band-structure technique, the electronic structure of model Si-Si/sub 1-x/Ge/sub x/ and MOS superlattices has been obtained over a wide range of layer thickness d (11 less than or equal to d less than or equal to 110 A). For d greater than or equal to 44 A, it is found that these systems exhibit a direct fundamental band gap. Further calculations of band-edge effective masses and impurity scattering rates suggest the possibility of a band-structure-driven enhancement in electron mobility over bulk silicon

  17. Shell structure of natural rubber particles: evidence of chemical stratification by electrokinetics and cryo-TEM.

    Science.gov (United States)

    Rochette, Christophe N; Crassous, Jérôme J; Drechsler, Markus; Gaboriaud, Fabien; Eloy, Marie; de Gaudemaris, Benoît; Duval, Jérôme F L

    2013-11-26

    The interfacial structure of natural rubber (NR) colloids is investigated by means of cryogenic transmission electron microscopy (cryo-TEM) and electrokinetics over a broad range of KNO3 electrolyte concentrations (4-300 mM) and pH values (1-8). The asymptotic plateau value reached by NR electrophoretic mobility (μ) in the thin double layer limit supports the presence of a soft (ion- and water-permeable) polyelectrolytic type of layer located at the periphery of the NR particles. This property is confirmed by the analysis of the electron density profile obtained from cryo-TEM that evidences a ∼2-4 nm thick corona surrounding the NR polyisoprene core. The dependence of μ on pH and salt concentration is further marked by a dramatic decrease of the point of zero electrophoretic mobility (PZM) from 3.6 to 0.8 with increasing electrolyte concentration in the range 4-300 mM. Using a recent theory for electrohydrodynamics of soft multilayered particles, this "anomalous" dependence of the PZM on electrolyte concentration is shown to be consistent with a radial organization of anionic and cationic groups across the peripheral NR structure. The NR electrokinetic response in the pH range 1-8 is indeed found to be equivalent to that of particles surrounded by a positively charged ∼3.5 nm thick layer (mean dissociation pK ∼ 4.2) supporting a thin and negatively charged outermost layer (0.6 nm in thickness, pK ∼ 0.7). Altogether, the strong dependence of the PZM on electrolyte concentration suggests that the electrostatic properties of the outer peripheral region of the NR shell are mediated by lipidic residues protruding from a shell containing a significant amount of protein-like charges. This proposed NR shell interfacial structure questions previously reported NR representations according to which the shell consists of either a fully mixed lipid-protein layer, or a layer of phospholipids residing exclusively beneath an outer proteic film.

  18. Gross shell structure at high spin in heavy nuclei

    International Nuclear Information System (INIS)

    Deleplanque, Marie-Agnes; Frauendorf, Stefan; Pashkevich, Vitaly V.; Chu, S.Y.; Unzhakova, Anja

    2003-01-01

    Experimental nuclear moments of inertia at high spins along the yrast line have been determined systematically and found to differ from the rigid-body values. The difference is attributed to shell effect and these have been calculated microscopically. The data and quantal calculations are interpreted by means of the semiclassical Periodic Orbit Theory. From this new perspective, features in the moments of inertia as a function of neutron number and spin, as well as their relation to the shell energies can be understood. Gross shell effects persist up to the highest angular momenta observed

  19. Electronic transport properties of 4f shell elements of liquid metal using hard sphere Yukawa system

    Science.gov (United States)

    Patel, H. P.; Sonvane, Y. A.; Thakor, P. B.

    2018-04-01

    The electronic transport properties are analyzed for 4f shell elements of liquid metals. To examine the electronic transport properties like electrical resistivity (ρ), thermal conductivity (σ) and thermo electrical power (Q), we used our own parameter free model potential with the Hard Sphere Yukawa (HSY) reference system. The screening effect on aforesaid properties has been examined by using different screening functions like Hartree (H), Taylor (T) and Sarkar (S). The correlations of our resultsand other data with available experimental values are intensely promising. Also, we conclude that our newly constructed parameter free model potential is capable of explaining the above mentioned electronic transport properties.

  20. Contribution of inner shell electrons to position-dependent stopping powers of a crystal surface

    International Nuclear Information System (INIS)

    Narumi, Kazumasa; Fujii, Yoshikazu; Kishine, Keiji; Kurakake, Hiroshi; Kimura, Kenji; Mannami, Michi-hiko

    1994-01-01

    Position-dependent stopping powers of the (001) surface of SnTe single crystal for specularly reflected 15 - 200 keV H + ions are studied. The position dependence of the experimental stopping powers varies with the energy of ions. From the comparison with the theoretical stopping powers based on both the single ion-electron collision and the collective excitation of the valence electrons, it is concluded that the observed change in the position-dependent stopping powers with energy of H + is due to the variation of contribution of inner shell electrons to stopping. (author)

  1. Dynamics of valence-shell electrons and nuclei probed by strong-field holography and rescattering

    Science.gov (United States)

    Walt, Samuel G.; Bhargava Ram, Niraghatam; Atala, Marcos; Shvetsov-Shilovski, Nikolay I; von Conta, Aaron; Baykusheva, Denitsa; Lein, Manfred; Wörner, Hans Jakob

    2017-01-01

    Strong-field photoelectron holography and laser-induced electron diffraction (LIED) are two powerful emerging methods for probing the ultrafast dynamics of molecules. However, both of them have remained restricted to static systems and to nuclear dynamics induced by strong-field ionization. Here we extend these promising methods to image purely electronic valence-shell dynamics in molecules using photoelectron holography. In the same experiment, we use LIED and photoelectron holography simultaneously, to observe coupled electronic-rotational dynamics taking place on similar timescales. These results offer perspectives for imaging ultrafast dynamics of molecules on femtosecond to attosecond timescales. PMID:28643771

  2. The shell model. Towards a unified description of nuclear structure

    Energy Technology Data Exchange (ETDEWEB)

    Poves, Alfredo [Departamento de Fisica Teorica, Universidad Autonoma Cantoblanco, 28049 - Madrid (Spain); Collaboration: La Direction des Sciences de la Matiere du CEA (FR); Le Fonds National de la Recherche Scientifique de Belgique (BE)

    1998-12-31

    In this series of lectures we present the foundations of the spherical shell model that we treat as an approximation to the exact solution of the full secular problem. We introduce the notions of valence space, effective interaction and effective operator. We analyse the structure of the realistic effective interactions, identifying their monopole part with the spherical mean field. The multipole Hamiltonian is shown to have a universal (simple) form that includes pairing (isovector and isoscalar), quadrupole, octupole, deca-pole, and ({sigma}{center_dot}{tau})({sigma}{center_dot}{tau}). We describe the methods of resolution of the secular problem, in particular the Lanczos method. The model is applied to the description of nuclear deformation and its relationship with the deformed mean field theories is studied. We propose a new symmetry, `quasi`-SU3, to understand deformation in the spherical basis. Finally, we discuss the domain of nuclei very far from the valley of {beta} stability, addressing the vanishing of some magic closures that can be explained in terms of intruder states. (author) 53 refs., 20 figs., 3 tabs.

  3. The shell model. Towards a unified description of nuclear structure

    International Nuclear Information System (INIS)

    Poves, Alfredo

    1998-01-01

    In this series of lectures we present the foundations of the spherical shell model that we treat as an approximation to the exact solution of the full secular problem. We introduce the notions of valence space, effective interaction and effective operator. We analyse the structure of the realistic effective interactions, identifying their monopole part with the spherical mean field. The multipole Hamiltonian is shown to have a universal (simple) form that includes pairing (isovector and isoscalar), quadrupole, octupole, deca-pole, and (σ·τ)(σ·τ). We describe the methods of resolution of the secular problem, in particular the Lanczos method. The model is applied to the description of nuclear deformation and its relationship with the deformed mean field theories is studied. We propose a new symmetry, 'quasi'-SU3, to understand deformation in the spherical basis. Finally, we discuss the domain of nuclei very far from the valley of β stability, addressing the vanishing of some magic closures that can be explained in terms of intruder states. (author)

  4. Nickel oxide/polypyrrole/silver nanocomposites with core/shell/shell structure: Synthesis, characterization and their electrochemical behaviour with antimicrobial activities

    Energy Technology Data Exchange (ETDEWEB)

    Das, Dhaneswar; Nath, Bikash C. [Department of Chemical Sciences, Tezpur University, Tezpur 784028, Assam (India); Phukon, Pinkee [Department of Molecular Biology and Biotechnology, Tezpur University, Tezpur 784028, Assam (India); Saikia, Bhaskar J.; Kamrupi, Isha R. [Department of Chemical Sciences, Tezpur University, Tezpur 784028, Assam (India); Dolui, Swapan K., E-mail: dolui@tezu.ernet.in [Department of Chemical Sciences, Tezpur University, Tezpur 784028, Assam (India)

    2013-10-01

    Magnetic and conducting Nickel oxide–polypyrrole (NiO/PPy) nanoparticles with core–shell structure were prepared in the presence of Nickel oxide (NiO) in aqueous solution containing sodium dodecyl benzenesulfonate (SDBS) as a surfactant as well as dopant. A stable dispersion of silver (Ag) nanoparticles was synthesized by chemical (citrate reduction) method. NiO/PPy nanocomposites were added to the Ag colloid under stirring. Ag nanoparticles could be electrostatically attracted on the surface of NiO/PPy nanocomposites, leading to formation of NiO/PPy/Ag nanocomposites with core/shell/shell structure. The morphology, structure, particle size and composition of the products were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, cyclic voltammetry (CV) and current–voltage (I–V) analysis. The resultant nanocomposites have the good conductivity and excellent electrochemical and catalytic properties of PPy and Ag nanoparticles. Furthermore, the nanocomposites showed excellent antibacterial behaviour due to the presence of Ag nanoparticles in the composite. The thermal stability of NiO–PPy as well as NiO/PPy/Ag nanocomposites was higher than that of pristine PPy. Studies of IR spectra suggest that the increased thermal stability may be due to interactions between NiO and Ag nanoparticles with the PPy backbone. - Highlights: • NiO nanoparticles were synthesized by two step soft chemical synthesis route. • Ag nanoparticles were prepared by using citrate reduction method. • NiO/PPy nanocomposites are synthesized by chemical oxidative polymerization process. • NiO/PPy/Ag nanocomposites can be used in the water purification technology.

  5. Nickel oxide/polypyrrole/silver nanocomposites with core/shell/shell structure: Synthesis, characterization and their electrochemical behaviour with antimicrobial activities

    International Nuclear Information System (INIS)

    Das, Dhaneswar; Nath, Bikash C.; Phukon, Pinkee; Saikia, Bhaskar J.; Kamrupi, Isha R.; Dolui, Swapan K.

    2013-01-01

    Magnetic and conducting Nickel oxide–polypyrrole (NiO/PPy) nanoparticles with core–shell structure were prepared in the presence of Nickel oxide (NiO) in aqueous solution containing sodium dodecyl benzenesulfonate (SDBS) as a surfactant as well as dopant. A stable dispersion of silver (Ag) nanoparticles was synthesized by chemical (citrate reduction) method. NiO/PPy nanocomposites were added to the Ag colloid under stirring. Ag nanoparticles could be electrostatically attracted on the surface of NiO/PPy nanocomposites, leading to formation of NiO/PPy/Ag nanocomposites with core/shell/shell structure. The morphology, structure, particle size and composition of the products were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, cyclic voltammetry (CV) and current–voltage (I–V) analysis. The resultant nanocomposites have the good conductivity and excellent electrochemical and catalytic properties of PPy and Ag nanoparticles. Furthermore, the nanocomposites showed excellent antibacterial behaviour due to the presence of Ag nanoparticles in the composite. The thermal stability of NiO–PPy as well as NiO/PPy/Ag nanocomposites was higher than that of pristine PPy. Studies of IR spectra suggest that the increased thermal stability may be due to interactions between NiO and Ag nanoparticles with the PPy backbone. - Highlights: • NiO nanoparticles were synthesized by two step soft chemical synthesis route. • Ag nanoparticles were prepared by using citrate reduction method. • NiO/PPy nanocomposites are synthesized by chemical oxidative polymerization process. • NiO/PPy/Ag nanocomposites can be used in the water purification technology

  6. Shell-like structures advanced theories and applications

    CERN Document Server

    Eremeyev, Victor

    2017-01-01

    The book presents mathematical and mechanical aspects of the theory of plates and shells, applications in civil, aero-space and mechanical engineering, as well in other areas. The focus relates to the following problems: • comprehensive review of the most popular theories of plates and shells, • relations between three-dimensional theories and two-dimensional ones, • presentation of recently developed new refined plates and shells theories (for example, the micropolar theory or gradient-type theories), • modeling of coupled effects in shells and plates related to electromagnetic and temperature fields, phase transitions, diffusion, etc., • applications in modeling of non-classical objects like, for example, nanostructures, • presentation of actual numerical tools based on the finite element approach.

  7. Diffraction and absorption of inelastically scattered electrons for K-shell ionization

    International Nuclear Information System (INIS)

    Josefsson, T.W.; Allen, L.J.

    1995-01-01

    An expression for the nonlocal inelastic scattering cross section for fast electrons in a crystalline environment, which explicitly includes diffraction as well as absorption for the inelastically scattered electrons, is used to carry out realistic calculations of K-shell electron energy loss spectroscopy (EELS) and energy dispersive x-ray (EDX) analysis cross sections. The calculations demonstrate quantitatively why, in EDX spectroscopy, integration over the dynamical states of the inelastically scattered electron averages in such a way that an effective plane wave representation of the scattered electrons is a good approximation. This is only the case for large enough acceptance angles of the detector in an EELS experiment. For EELS with smaller detector apertures, explicit integration over the dynamical final states is necessary and inclusion of absorption for the scattered electrons is important, particularly for thicker crystals. 50 refs., 7 figs

  8. Semiclassical shell structure of moments of inertia in deformed Fermi systems

    International Nuclear Information System (INIS)

    Magner, A.G.; Gzhebinsky, A.M.; Sitdikov, A.S.; Khamzin, A.A.; Bartel, J.

    2010-01-01

    The collective moment of inertia is derived analytically within the cranking model in the adiabatic mean-field approximation at finite temperature. Using the nonperturbative periodic-orbit theory the semiclassical shell-structure components of the collective moment of inertia are obtained for any potential well. Their relation to the free-energy shell corrections are found semiclassically as being given through the shell-structure components of the rigid-body moment of inertia of the statistically equilibrium rotation in terms of short periodic orbits. Shell effects in the moment of inertia disappear exponentially with increasing temperature. For the case of the harmonic-oscillator potential one observes a perfect agreement between semiclassical and quantum shell-structure components of the free energy and the moment of inertia for several critical bifurcation deformations and several temperatures. (author)

  9. Design, fabrication and test of a lightweight shell structure, phase 3

    Science.gov (United States)

    1977-01-01

    Progress is reported in the construction of lightweight orthogrid shells. Graphite/epoxy panels are being used in the fabrication. The shell structure is diagramed in detail. Panel laminates, and panel stiffener flanges are described while illustrations delineate panel assembly procedures.

  10. Growth of InAs/InP core-shell nanowires with various pure crystal structures.

    Science.gov (United States)

    Gorji Ghalamestani, Sepideh; Heurlin, Magnus; Wernersson, Lars-Erik; Lehmann, Sebastian; Dick, Kimberly A

    2012-07-20

    We have studied the epitaxial growth of an InP shell on various pure InAs core nanowire crystal structures by metal-organic vapor phase epitaxy. The InP shell is grown on wurtzite (WZ), zinc-blende (ZB), and {111}- and {110}-type faceted ZB twin-plane superlattice (TSL) structures by tuning the InP shell growth parameters and controlling the shell thickness. The growth results, particularly on the WZ nanowires, show that homogeneous InP shell growth is promoted at relatively high temperatures (∼500 °C), but that the InAs nanowires decompose under the applied conditions. In order to protect the InAs core nanowires from decomposition, a short protective InP segment is first grown axially at lower temperatures (420-460 °C), before commencing the radial growth at a higher temperature. Further studies revealed that the InP radial growth rate is significantly higher on the ZB and TSL nanowires compared to WZ counterparts, and shows a strong anisotropy in polar directions. As a result, thin shells were obtained during low temperature InP growth on ZB structures, while a higher temperature was used to obtain uniform thick shells. In addition, a schematic growth model is suggested to explain the basic processes occurring during the shell growth on the TSL crystal structures.

  11. Growth of InAs/InP core–shell nanowires with various pure crystal structures

    International Nuclear Information System (INIS)

    Gorji Ghalamestani, Sepideh; Heurlin, Magnus; Lehmann, Sebastian; Dick, Kimberly A; Wernersson, Lars-Erik

    2012-01-01

    We have studied the epitaxial growth of an InP shell on various pure InAs core nanowire crystal structures by metal–organic vapor phase epitaxy. The InP shell is grown on wurtzite (WZ), zinc-blende (ZB), and {111}- and {110}-type faceted ZB twin-plane superlattice (TSL) structures by tuning the InP shell growth parameters and controlling the shell thickness. The growth results, particularly on the WZ nanowires, show that homogeneous InP shell growth is promoted at relatively high temperatures (∼500 °C), but that the InAs nanowires decompose under the applied conditions. In order to protect the InAs core nanowires from decomposition, a short protective InP segment is first grown axially at lower temperatures (420–460 °C), before commencing the radial growth at a higher temperature. Further studies revealed that the InP radial growth rate is significantly higher on the ZB and TSL nanowires compared to WZ counterparts, and shows a strong anisotropy in polar directions. As a result, thin shells were obtained during low temperature InP growth on ZB structures, while a higher temperature was used to obtain uniform thick shells. In addition, a schematic growth model is suggested to explain the basic processes occurring during the shell growth on the TSL crystal structures. (paper)

  12. Silver atom solvation and desolvation in ice matrices: study of solvation shell geometry by electron spin resonance and electron spin echo methods

    Energy Technology Data Exchange (ETDEWEB)

    Kevan, L; Narayana, P A

    1978-01-01

    Results of studies of the solvation shell structure of silver atoms in ice matrix at 4/sup 0/K by electron spin resonance (ESR) and electron spin echo spectrometry are reported. Drastic change in the hyperfine coupling constant of the silver atom was noted when the silver atom initially produced at 4/sup 0/K was warmed to 77/sup 0/K and reexamined by ESR at 4/sup 0/K. This suggested a very drastic rearrangement of the water molecules surrounding the silver atom. The geometric arrangement of water molecules around the silver atom produced at 4/sup 0/K was what would be expected for a solvated silver ion, indicating that no rearrangement had occurred after the silver atom formed. The addition of a little thermal excitation (heating to 77/sup 0/K) results in the geometry changes than can be explained by assuming either that a water molecule rotates around one of its OH bands or by the development of a hydrogen bond between the silver atom and one of the first solvation shell water molecules. Optical excitation in the absorption band of the silver atom in the ice matrix at 400nm resulted in desolvation of the silver ion or a reversion to the structure originally obtained by reaction of solver salts in ic matrix with radiation produced electrons. This was best explained by a charge transfer mechanism. (BLM)

  13. Hylleraas-like functions with the correct cusp conditions: K-shell electrons for the neutral atoms

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, K.V. [Universidad Nacional del Sur, 8000 Bahia Blanca and Consejo Nacional de Investigaciones Cientificas y Tecnicas (Argentina)], E-mail: krodri@criba.edu.ar; Gasaneo, G. [Universidad Nacional del Sur, 8000 Bahia Blanca and Consejo Nacional de Investigaciones Cientificas y Tecnicas (Argentina); Mitnik, D.M.; Miraglia, J.E. [Instituto de Astronomia y Fisica del Espacio and Universidad de Buenos Aires (Argentina)

    2007-10-15

    We present simple correlated wavefunctions for the two K-shell electrons of neutral atoms. A variational method was chosen to calculate the mean energy of the ground state, in which the electrons are subject to a local Hartree potential representing the presence of the outer shell electrons. The functions are constructed in terms of exponential and power series, where special care has been taken in order to fulfill the exact behavior at the electron-electron and electron-nucleus coalescence points (Kato cusp conditions). Global properties, such as the energies and virial coefficients, as well as local properties, such as spatial mean values, are also analyzed.

  14. Linked-cluster perturbation theory for closed and open-shell systems: derivation of effective π-electron hamiltonians

    International Nuclear Information System (INIS)

    Brandow, B.H.

    1977-01-01

    The Brueckner--Goldstone form of linked-cluster perturbation theory is derived, together with its open-shell analog, by an elementary time-independent approach. This serves to focus attention on the physical interpretation of the results. The open-shell expansion is used to provide a straightforward justification for the effective π-electron Hamiltonians of planar organic molecules

  15. Curly arrows meet electron density transfers in chemical reaction mechanisms: from electron localization function (ELF) analysis to valence-shell electron-pair repulsion (VSEPR) inspired interpretation.

    Science.gov (United States)

    Andrés, Juan; Berski, Sławomir; Silvi, Bernard

    2016-07-07

    Probing the electron density transfers during a chemical reaction can provide important insights, making possible to understand and control chemical reactions. This aim has required extensions of the relationships between the traditional chemical concepts and the quantum mechanical ones. The present work examines the detailed chemical insights that have been generated through 100 years of work worldwide on G. N. Lewis's ground breaking paper on The Atom and the Molecule (Lewis, G. N. The Atom and the Molecule, J. Am. Chem. Soc. 1916, 38, 762-785), with a focus on how the determination of reaction mechanisms can be reached applying the bonding evolution theory (BET), emphasizing how curly arrows meet electron density transfers in chemical reaction mechanisms and how the Lewis structure can be recovered. BET that combines the topological analysis of the electron localization function (ELF) and Thom's catastrophe theory (CT) provides a powerful tool providing insight into molecular mechanisms of chemical rearrangements. In agreement with physical laws and quantum theoretical insights, BET can be considered as an appropriate tool to tackle chemical reactivity with a wide range of possible applications. Likewise, the present approach retrieves the classical curly arrows used to describe the rearrangements of chemical bonds for a given reaction mechanism, providing detailed physical grounds for this type of representation. The ideas underlying the valence-shell-electron pair-repulsion (VSEPR) model applied to non-equilibrium geometries provide simple chemical explanations of density transfers. For a given geometry around a central atom, the arrangement of the electronic domain may comply or not with the VSEPR rules according with the valence shell population of the considered atom. A deformation yields arrangements which are either VSEPR defective (at least a domain is missing to match the VSEPR arrangement corresponding to the geometry of the ligands), VSEPR compliant

  16. Facile one-step synthesis and photoluminescence properties of Ag–ZnO core–shell structure

    International Nuclear Information System (INIS)

    Zhai, HongJu; Wang, LiJing; Han, DongLai; Wang, Huan; Wang, Jian; Liu, XiaoYan; Lin, Xue; Li, XiuYan; Gao, Ming; Yang, JingHai

    2014-01-01

    Graphical abstract: The PL of the Ag–ZnO core-shell nanostructure showed obvious increase of UV emission and slight decrease of visible light emission compared to that of the pure ZnO. With the calcination temperature increasing from 300 to 600 °C, the primary peak located at 380 nm became stronger and sharper, indicating that the increasing calcination temperature made the samples crystallize better. - Highlights: • Ag-ZnO core-shell structure was obtained via a simple one-step solvothermal process. • The approach was simple, mild, low cost, reproducible and easy-to-handle. • The obvious enhancement of UV luminescent has been observed. • Effects of the calcining temperature to luminescence were investigated in detail. - Abstract: Ag–ZnO core–shell structures were gained via one-step solvothermal process. The products were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman spectroscopy, photoluminescence (PL) and UV–vis spectroscopy, respectively. It was shown that the properties were greatly changed compared to pure ZnO from the PL and Raman spectra, which indicated the strong interfacial interaction between ZnO and Ag. The work provides a feasible method to synthesize Ag–ZnO core–shell structure photocatalyst, which is promising in the further practical application of ZnO-based photocatalytic materials

  17. Analysis of thin composite structures using an efficient hex-shell finite element

    Energy Technology Data Exchange (ETDEWEB)

    Shiri, Seddik [Universite Bordeaux, Pessac (France); Naceur, Hakim [Universite de valenciennes, Valenciennes (France)

    2013-12-15

    In this paper a general methodology for the modeling of material composite multilayered shell structures is proposed using a Hex-shell finite element modeling. The first part of the paper is devoted to the general FE formulation of the present composite 8-node Hex-shell element called SCH8, based only on displacement degrees of freedom. A particular attention is given to alleviate shear, trapezoidal and thickness locking, without resorting to the classical plane-stress assumption. The anisotropic material behavior of layered shells is modeled using a fully three dimensional elastic orthotropic material law in each layer, including the thickness stress component. Applications to laminate thick shell structures are studied to validate the methodology, and good results have been obtained in comparison with ABAQUS commercial code.

  18. Stereo and scanning electron microscopy of in-shell Brazil nut (Bertholletia excelsa H.B.K.): part two-surface sound nut fungi spoilage susceptibility.

    Science.gov (United States)

    Scussel, Vildes M; Manfio, Daniel; Savi, Geovana D; Moecke, Elisa H S

    2014-11-01

    This work reports the in-shell Brazil nut spoilage susceptible morpho-histological characteristics and fungi infection (shell, edible part, and brown skin) through stereo and scanning electron microscopies (SEM). The following characteristics related to shell (a) morphology-that allow fungi and insects' entrance to inner nut, and (b) histology-that allow humidity absorption, improving environment conditions for living organisms development, were identified. (a.1) locule in testae-the nut navel, which is a cavity formed during nut detaching from pods (located at 1.0 to 2.0/4th of the shell B&C nut faces linkage). It allows the nut brown skin (between shell and edible part) first contact to the external environment, through the (a.2) nut channel-the locule prolongation path, which has the water/nutrients cambium function for their transport and distribution to the inner seed (while still on the tree/pod). Both, locule followed by the channel, are the main natural entrance of living organisms (fungi and insects), including moisture to the inner seed structures. In addition, the (a.3) nut shell surface-which has a crinkled and uneven surface morphology-allows water absorption, thus adding to the deterioration processes too. The main shell histological characteristic, which also allows water absorption (thus improving environment conditions for fungi proliferation), is the (b.1) cell wall porosity-the multilayered wall and porous rich cells that compose the shell faces double tissue layers and the (b.2) soft tissue-the mix of tissues 2 faces corner/linkage. This work also shows in details the SEM nut spoilage susceptible features highly fungi infected with hyphae and reproductive structures distribution. © 2014 Institute of Food Technologists®

  19. Electronic structure and correlation effects in actinides

    International Nuclear Information System (INIS)

    Albers, R.C.

    1998-01-01

    This report consists of the vugraphs given at a conference on electronic structure. Topics discussed are electronic structure, f-bonding, crystal structure, and crystal structure stability of the actinides and how they are inter-related

  20. Ballistic transport and electronic structure

    NARCIS (Netherlands)

    Schep, Kees M.; Kelly, Paul J.; Bauer, Gerrit E.W.

    1998-01-01

    The role of the electronic structure in determining the transport properties of ballistic point contacts is studied. The conductance in the ballistic regime is related to simple geometrical projections of the Fermi surface. The essential physics is first clarified for simple models. For real

  1. The Electronic Structure of Calcium

    DEFF Research Database (Denmark)

    Jan, J.-P.; Skriver, Hans Lomholt

    1981-01-01

    The electronic structure of calcium under pressure is re-examined by means of self-consistent energy band calculations based on the local density approximation and using the linear muffin-tin orbitals (LMTO) method with corrections to the atomic sphere approximation included. At zero pressure...

  2. Electronic structure of metal clusters

    International Nuclear Information System (INIS)

    Wertheim, G.K.

    1989-01-01

    Photoemission spectra of valence electrons in metal clusters, together with threshold ionization potential measurements, provide a coherent picture of the development of the electronic structure from the isolated atom to the large metallic cluster. An insulator-metal transition occurs at an intermediate cluster size, which serves to define the boundary between small and large clusters. Although the outer electrons may be delocalized over the entire cluster, a small cluster remains insulating until the density of states near the Fermi level exceeds 1/kT. In large clusters, with increasing cluster size, the band structure approaches that of the bulk metal. However, the bands remain significantly narrowed even in a 1000-atom cluster, giving an indication of the importance of long-range order. The core-electron binding-energy shifts of supported metal clusters depend on changes in the band structure in the initial state, as well as on various final-state effects, including changes in core hole screening and the coulomb energy of the final-state charge. For cluster supported on amorphous carbon, this macroscopic coulomb shift is often dominant, as evidenced by the parallel shifts of the core-electron binding energy and the Fermi edge. Auger data confirm that final-state effects dominate in cluster of Sn and some other metals. Surface atom core-level shifts provide a valuable guide to the contributions of initial-state changes in band structure to cluster core-electron binding energy shifts, especially for Au and Pt. The available data indicate that the shift observed in supported, metallic clusters arise largely from the charge left on the cluster by photoemission. As the metal-insulator transition is approached from above, metallic screening is suppressed and the shift is determined by the local environment. (orig.)

  3. A study of the valence shell electronic states of s-triazine by photoabsorption spectroscopy and ab initio calculations

    Energy Technology Data Exchange (ETDEWEB)

    Holland, D.M.P., E-mail: david.holland@stfc.ac.uk [Daresbury Laboratory, Daresbury, Warrington, Cheshire WA4 4AD (United Kingdom); Shaw, D.A. [Daresbury Laboratory, Daresbury, Warrington, Cheshire WA4 4AD (United Kingdom); Stener, M.; Decleva, P. [Dipartimento di Scienze Chimiche e Farmaceutiche, Università degli Studi di Trieste, Via L. Giorgieri, I-34127 Trieste (Italy); Consorzio Interuniversitario Nazionale per la Scienze e Tecnologia dei Materiali, INSTM, Unità di Trieste (Italy); CNR-IOM, Trieste (Italy); Coriani, S. [Dipartimento di Scienze Chimiche e Farmaceutiche, Università degli Studi di Trieste, Via L. Giorgieri, I-34127 Trieste (Italy); Consorzio Interuniversitario Nazionale per la Scienze e Tecnologia dei Materiali, INSTM, Unità di Trieste (Italy); Aarhus Institute of Advanced Studies, Aarhus University, 8000 Aarhus C (Denmark)

    2016-09-30

    Highlights: • The valence shell photoabsorption spectrum of s-triazine has been measured. • Electronic structure calculated with TDDFT and coupled cluster approaches. • Assignments proposed for Rydberg and valence states. • Mixing between Rydberg and valence states important. - Abstract: The absolute photoabsorption cross section of s-triazine has been measured between 4 and 40 eV, and is dominated by bands associated with valence states. Structure due to Rydberg excitations is both weak and irregular. Jahn-Teller interactions affect the vibronic structure observed in the Rydberg absorption bands due to excitation from the 1e″ or 6e′ orbitals. The interpretation of the experimental spectrum has been guided by transition energies and oscillator strengths, for Rydberg and valence states, calculated with the time-dependent version of density functional theory and with the coupled cluster linear response approach. The theoretical studies indicate that Rydberg/Rydberg and Rydberg/valence mixing is important.

  4. Single and multi-layered core-shell structures based on ZnO nanorods obtained by aerosol assisted chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Sáenz-Trevizo, A.; Amézaga-Madrid, P.; Pizá-Ruiz, P.; Antúnez-Flores, W.; Ornelas-Gutiérrez, C.; Miki-Yoshida, M., E-mail: mario.miki@cimav.edu.mx

    2015-07-15

    Core–shell nanorod structures were prepared by a sequential synthesis using an aerosol assisted chemical vapor deposition technique. Several samples consisting of ZnO nanorods were initially grown over TiO{sub 2} film-coated borosilicate glass substrates, following the synthesis conditions reported elsewhere. Later on, a uniform layer consisting of individual Al, Ni, Ti or Fe oxides was grown onto ZnO nanorod samples forming the so-called single MO{sub x}/ZnO nanorod core–shell structures, where MO{sub x} was the metal oxide shell. Additionally, a three-layer core–shell sample was developed by growing Fe, Ti and Fe oxides alternately, onto the ZnO nanorods. The microstructure of the core–shell materials was characterized by grazing incidence X-ray diffraction, scanning and transmission electron microscopy. Energy dispersive X-ray spectroscopy was employed to corroborate the formation of different metal oxides. X-ray diffraction outcomes for single core–shell structures showed solely the presence of ZnO as wurtzite and TiO{sub 2} as anatase. For the multi-layered shell sample, the existence of Fe{sub 2}O{sub 3} as hematite was also detected. Morphological observations suggested the existence of an outer material grown onto the nanorods and further microstructural analysis by HR-STEM confirmed the development of core–shell structures in all cases. These studies also showed that the individual Al, Fe, Ni and Ti oxide layers are amorphous; an observation that matched with X-ray diffraction analysis where no apparent extra oxides were detected. For the multi-layered sample, the development of a shell consisting of three different oxide layers onto the nanorods was found. Overall results showed that no alteration in the primary ZnO core was produced during the growth of the shells, indicating that the deposition technique used herein was and it is suitable for the synthesis of homogeneous and complex nanomaterials high in quality and purity. In addition

  5. Facile synthesis of flower like FePt@ZnO core–shell structure and its bifunctional properties

    Energy Technology Data Exchange (ETDEWEB)

    Majeed, Jerina [Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Jayakumar, O.D., E-mail: ddjaya@barc.gov.in [Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Mandal, B.P. [Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Salunke, H.G. [Technical Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Naik, R. [Department of Physics, Wayne State University, Detroit, MI 48202 (United States); Tyagi, A.K., E-mail: aktyagi@barc.gov.in [Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)

    2014-06-01

    Graphical abstract: Flower shaped FePt and ZnO coated FePt with core–shell nanostructures are synthesized by a facile solvothermal procedure. Shell thickness of ZnO over FePt core was tuned by varying FePt concentration with respect to ZnO. Hybrid structure with lower FePt concentration exhibited bifunctionality such as near room temperature ferromagnetism and photoluminescence. Pristine FePt crystallize in the fct (L1{sub 0}) phase whereas it converts into fcc phase in presence of ZnO. - Highlights: • FePt@ZnO hybrid core–shell particles, with unique flower shape morphology have been prepared by solvothermal method. • Phase transition of fct-FePt to fcc-FePt has been found in presence of ZnO nanoparticles. • Plausible mechanism for growth of flowershaped nanoparticle is in accordance with energy minimization principle. • The core shell structure (FePt@ZnO) exhibits bi-functional properties. - Abstract: Flower shaped FePt and ZnO coated FePt (FePt@ZnO) core–shell nanostructures are synthesized by a facile solvothermal procedure. Two different compositions (molar ratio) of FePt and ZnO (FePt:ZnO = 1:3 and FePt:ZnO = 1:6) core–shells with different thicknesses of ZnO shells were synthesized. Hybrid FePt@ZnO core–shell flower structure with lower FePt concentration (FePt:ZnO = 1:6) exhibited bifunctionality including near room temperature ferromagnetism and photoluminescence at ambient conditions. X-ray diffraction patterns of pristine FePt showed partially ordered face centred tetragonal (fct) L1{sub 0} phase whereas ZnO coated FePt (FePt@ZnO) nanostructures showed hexagonal ZnO and disordered phase of FePt with fcc structure. The phase transition of fct FePt to fcc phase occurring in presence of ZnO is further confirmed by transmission electron microscopy and magnetic measurement studies. The formation of the nanoflowers was possibly due to growth along the [0 1 1] or [0 0 1] direction, keeping the core nearly spherical in accordance with the

  6. Structure function of off-mass-shell pions and the calculation of the Sullivan process

    International Nuclear Information System (INIS)

    Shakin, C.M.; Sun, W.

    1994-01-01

    We construct a model for the pion (valence) structure function that fits the experimental data obtained in the study of the Drell-Yan process. The model may also be used to calculate the structure function of off-mass-shell pions. We apply our model in the study of deep-inelastic scattering from off-mass-shell pions found in the nucleon and are thus able to resolve a problem encountered in the standard analysis of such processes. The usual analysis is made using the structure function of on-mass-shell pions and requires the use of a soft πNN form factor that is inconsistent with standard nuclear physics phenomenology. The use of our off-mass-shell structure functions allows for a fit to the data for nonperturbative aspects of the nucleon ''sea'' with a pion-nucleon form factor of the standard form

  7. Structure of exotic nuclei by large-scale shell model calculations

    International Nuclear Information System (INIS)

    Utsuno, Yutaka; Otsuka, Takaharu; Mizusaki, Takahiro; Honma, Michio

    2006-01-01

    An extensive large-scale shell-model study is conducted for unstable nuclei around N = 20 and N = 28, aiming to investigate how the shell structure evolves from stable to unstable nuclei and affects the nuclear structure. The structure around N = 20 including the disappearance of the magic number is reproduced systematically, exemplified in the systematics of the electromagnetic moments in the Na isotope chain. As a key ingredient dominating the structure/shell evolution in the exotic nuclei from a general viewpoint, we pay attention to the tensor force. Including a proper strength of the tensor force in the effective interaction, we successfully reproduce the proton shell evolution ranging from N = 20 to 28 without any arbitrary modifications in the interaction and predict the ground state of 42Si to contain a large deformed component

  8. Magnetic properties of Co-ferrite-doped hydroxyapatite nanoparticles having a core/shell structure

    International Nuclear Information System (INIS)

    Petchsang, N.; Pon-On, W.; Hodak, J.H.; Tang, I.M.

    2009-01-01

    The magnetic properties of Co-ferrite-doped hydroxyapatite (HAP) nanoparticles of composition Ca 10-3x Fe 2x Co x (PO 4 ) 6 (OH) 2 (where x=0, 0.1, 0.2, 0.3, 0.4 and 0.5% mole) are studied. Transmission electron microscope micrograms show that the 90 nm size nanoparticles annealed at 1250 o C have a core/shell structure. Their electron diffraction patterns show that the shell is composed of the hydroxyapatite and the core is composed of the Co-ferrite, CoFe 2 O 4 . Electron spin resonance measurements indicate that the Co 2+ ions are being substituted into the Ca(1) sites in HAP lattice. X-ray diffraction studies show the formation of impurity phases as higher amounts of the Fe 3+ /Co 2+ ions which are substituted into the HAP host matrix. The presence of two sextets (one for the A-site Fe 3+ and the other for the B-site Fe 3+ ) in the Moessbauer spectrum for all the doped samples clearly indicates that the CoFe 2 O 4 .cores are in the ferromagnetic state. Evidence of the impurity phases is seen in the appearance of doublet patterns in the Moessbauer spectrums for the heavier-doped (x=0.4 and 0.5) specimens. The decrease in the saturation magnetizations and other magnetic properties of the nanoparticles at the higher doping levels is consistent with some of the Fe 3+ and Co 2+ which being used to form the CoO and Fe 2 O 3 impurity phase seen in the XRD patterns.

  9. Core-Shell Structured Electro- and Magneto-Responsive Materials: Fabrication and Characteristics

    Directory of Open Access Journals (Sweden)

    Hyoung Jin Choi

    2014-11-01

    Full Text Available Core-shell structured electrorheological (ER and magnetorheological (MR particles have attracted increasing interest owing to their outstanding field-responsive properties, including morphology, chemical and dispersion stability, and rheological characteristics of shear stress and yield stress. This study covers recent progress in the preparation of core-shell structured materials as well as their critical characteristics and advantages. Broad emphasises from the synthetic strategy of various core-shell particles to their feature behaviours in the magnetic and electric fields have been elaborated.

  10. Wear Resistance and Mechanical Behaviour of Epoxy/Mollusk Shell Biocomposites developed for Structural Applications

    Directory of Open Access Journals (Sweden)

    I.O. Oladele

    2016-09-01

    Full Text Available Epoxy resin is one of the strongest commercially exploitable thermosetting polymers in the polymer family; however its expensive nature in comparison with other thermosetting polymers such as vinylester and polyester limits its applications as a structural material. Inexpensive fillers on the other hand, especially those derived from agro-industrial wastes are very important in reducing the overall cost of polymer composites and furthermore influential in enhancing some of their engineering properties. In the present study, the wear resistance and mechanical behaviour of epoxy polymer matrix filled with <75 and 75 μm calcined particles of African land snail shells have been comparatively investigated. The wear resistance and the mechanical behaviour of the composites were studied via Taber Abraser and INSTRON universal testing machine. Also, the elemental constituents of the calcined snail shell and the epoxy biocomposites were characterized by X-Ray Fluorescence Spectroscopy and Scanning Electron Microscopy/Energy Dispersion Spectroscopy. From the experimental results, it was observed that, at the highest filler loading, smaller particle size presented a biocomposite with significant enhancement in wear and mechanical properties. However, it was also observed that increase in particle size showed no significant enhancement in the mechanical properties of the biocomposites.

  11. Neoclassical Diffusion of Radiation-Belt Electrons Across Very Low L-Shells

    Science.gov (United States)

    Cunningham, Gregory S.; Loridan, Vivien; Ripoll, Jean-François; Schulz, Michael

    2018-04-01

    In the presence of drift-shell splitting intrinsic to the International Geomagnetic Reference Field magnetic field model, pitch angle scattering from Coulomb collisions experienced by radiation-belt electrons in the upper atmosphere and ionosphere produces extra radial diffusion, a form of neoclassical diffusion. The strength of the neoclassical radial diffusion at L nuclear detonation. The data show apparent lifetimes 10-100 times as long as would have been expected from collisional pitch angle diffusion and Coulomb drag alone. Our model reproduces apparent lifetimes for >0.5-MeV electrons in the region 1.14 < L < 1.26 to within a factor of 2 (comparable to the uncertainty quoted for the observations). We conclude that neoclassical radial diffusion (resulting from drift-shell splitting intrinsic to International Geomagnetic Reference Field's azimuthal asymmetries) mitigates the decay expected from collisional pitch angle diffusion and inelastic energy loss alone and thus contributes importantly to the long apparent lifetimes observed at these low L-shells.

  12. Effect of electron beam irradiation on mechanical properties of gelatin/Brazil nut shell fiber composites

    International Nuclear Information System (INIS)

    Inamura, Patricia Y.; Shimazaki, Kleber; Moura, Esperidiana Augusta Barretos de; Mastro, Nelida L. del; Colombo, Maria Aparecida; Rosa, Ricardo de

    2010-01-01

    The use of natural fiber as polymeric matrix reinforcement has attracted interest, as fibers are renewable, of low cost, biodegradable and possesses non-toxic properties. In the present paper, Brazil nuts (Bertholletia excelsa) shell fiber (10% w/w) were mixed with gelatin (25% w/w), glycerin as plasticizer and acrylamide as copolymer to investigate the resultant mechanical properties effects upon ionizing radiation. The samples were irradiated at 40 kGy using a Dynamitron electron beam accelerator, at room temperature in the presence of air. The results showed that samples of gelatin with 10% of Brazil nuts shell fiber and irradiated at 40 kGy presented promising results for mechanical performance. (author)

  13. Correlated electron capture and inner-shell excitation measurements in ion-atom collisions

    International Nuclear Information System (INIS)

    Tanis, J.A.; Bernstein, E.M.; Clark, M.W.

    1985-01-01

    In an ion-atom collision projectile excitation and charge transfer (electron capture) may occur together in a single encounter. If the excitation and capture are correlated, then the process is called resonant transfer and excitation (RTE); if they are uncorrelated, then the process is termed nonresonant transfer and excitation (NTE). Experimental work to date has shown the existence of RTE and provided strong evidence for NTE. Results presented here provide information on the relative magnitudes of RTE and NTE, the charge state dependence of RTE, the effect of the target momentum distribution on RTE, the magnitude of L-shell RTE compared to K-shell RTE, and the target Z dependences of RTE and NTE. 15 refs., 5 figs

  14. Organic-Inorganic Hydrophobic Nanocomposite Film with a Core-Shell Structure

    Directory of Open Access Journals (Sweden)

    Peng Liu

    2016-12-01

    Full Text Available A method to prepare novel organic-inorganic hydrophobic nanocomposite films was proposed by a site-specific polymerization process. The inorganic part, the core of the nanocomposite, is a ternary SiO2–Al2O3–TiO2 nanoparticles, which is grafted with methacryloxy propyl trimethoxyl silane (KH570, and wrapped by fluoride and siloxane polymers. The synthesized samples are characterized by transmission electron microscopy (TEM, Fourier transform infrared (FTIR spectrscopy, X-ray diffractometry (XRD, contact angle meter (CA, and scanning electron microscope (SEM. The results indicate that the novel organic-inorganic hydrophobic nanocomposite with a core-shell structure was synthesized successfully. XRD analysis reveals the nanocomposite film has an amorphous structure, and FTIR analysis indicates the nanoparticles react with a silane coupling agent (methacryloxy propyl trimethoxyl silane KH570. Interestingly, the morphology of the nanoparticle film is influenced by the composition of the core. Further, comparing with the film synthesized by silica nanoparticles, the film formed from SiO2–Al2O3–TiO2 nanoparticles has higher hydrophobic performance, i.e., the contact angle is greater than 101.7°. In addition, the TEM analysis reveals that the crystal structure of the particles can be changed at high temperatures.

  15. Mesoporous coaxial titanium nitride-vanadium nitride fibers of core-shell structures for high-performance supercapacitors.

    Science.gov (United States)

    Zhou, Xinhong; Shang, Chaoqun; Gu, Lin; Dong, Shanmu; Chen, Xiao; Han, Pengxian; Li, Lanfeng; Yao, Jianhua; Liu, Zhihong; Xu, Hongxia; Zhu, Yuwei; Cui, Guanglei

    2011-08-01

    In this study, titanium nitride-vanadium nitride fibers of core-shell structures were prepared by the coaxial electrospinning, and subsequently annealed in the ammonia for supercapacitor applications. These core-shell (TiN-VN) fibers incorporated mesoporous structure into high electronic conducting transition nitride hybrids, which combined higher specific capacitance of VN and better rate capability of TiN. These hybrids exhibited higher specific capacitance (2 mV s(-1), 247.5 F g(-1)) and better rate capability (50 mV s(-1), 160.8 F g(-1)), which promise a good candidate for high-performance supercapacitors. It was also revealed by electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) characterization that the minor capacitance fade originated from the surface oxidation of VN and TiN.

  16. Nitrite sensing composite systems based on a core-shell emissive-superamagnetic structure: Construction, characterization and sensing behavior

    Science.gov (United States)

    Yang, Yan; Liu, Liang; Zha, Jianhua; Yuan, Ningyi

    2017-04-01

    Two recyclable nitrite sensing composite samples were designed and constructed through a core-shell structure, with Fe3O4 nanoparticles as core, silica molecular sieve MCM-41 as shell and two rhodamine derivatives as chemosensors, respectively. These samples and their structure were identified with their electron microscopy images, N2 adsorption/desorption isotherms, magnetic response, IR spectra and thermogravimetric analysis. Their nitrite sensing behavior was discussed based on emission intensity quenching, their limit of detection was found as low as 1.2 μM. Further analysis suggested a static sensing mechanism between nitrite and chemosensors through an additive reaction between NO+ and chemosensors. After finishing their nitrite sensing, these composite samples and their emission could be recycled and recovered by sulphamic acid.

  17. ECO-TECHNIQUE OF SEWER RENOVATION USING COMPOSITE SHELLS: STRUCTURAL ANALYSIS

    Directory of Open Access Journals (Sweden)

    B. Attaf

    2015-07-01

    Full Text Available An eco-technical renovation of the sewage system is developed in this paper; this technique involves incorporating into the existing sewer a series of jointed prefabricated sandwich or composite shells. The purpose of his study is to determine the structural shell deflection, the high displacement areas and to validate the non-failure criterion for each ply constituting the inner and outer laminate facings. The numerical results were obtained at low cost by using the finite element method. Studies have focused on structural analysis of a typical shell unit with an ovoid form (egg-shaped section when it is subjected, during annular space filling operation, to pressure forces generated by wet concrete. To ensure the safety of the composite shell structure, Tsai-Hill criterion function is applied and results are presented for the most stressed plies

  18. Grid-based electronic structure calculations: The tensor decomposition approach

    Energy Technology Data Exchange (ETDEWEB)

    Rakhuba, M.V., E-mail: rakhuba.m@gmail.com [Skolkovo Institute of Science and Technology, Novaya St. 100, 143025 Skolkovo, Moscow Region (Russian Federation); Oseledets, I.V., E-mail: i.oseledets@skoltech.ru [Skolkovo Institute of Science and Technology, Novaya St. 100, 143025 Skolkovo, Moscow Region (Russian Federation); Institute of Numerical Mathematics, Russian Academy of Sciences, Gubkina St. 8, 119333 Moscow (Russian Federation)

    2016-05-01

    We present a fully grid-based approach for solving Hartree–Fock and all-electron Kohn–Sham equations based on low-rank approximation of three-dimensional electron orbitals. Due to the low-rank structure the total complexity of the algorithm depends linearly with respect to the one-dimensional grid size. Linear complexity allows for the usage of fine grids, e.g. 8192{sup 3} and, thus, cheap extrapolation procedure. We test the proposed approach on closed-shell atoms up to the argon, several molecules and clusters of hydrogen atoms. All tests show systematical convergence with the required accuracy.

  19. Elastic stability of cylindrical shells with soft elastic cores: Biomimicking natural tubular structures

    Science.gov (United States)

    Karam, Gebran Nizar

    1994-01-01

    Thin walled cylindrical shell structures are widespread in nature: examples include plant stems, porcupine quills, and hedgehog spines. All have an outer shell of almost fully dense material supported by a low density, cellular core. In nature, all are loaded in combination of axial compression and bending: failure is typically by buckling. Natural structures are often optimized. Here we have analyzed the elastic buckling of a thin cylindrical shell supported by an elastic core to show that this structural configuration achieves significant weight saving over a hollow cylinder. The results of the analysis are compared with data from an extensive experimental program on uniaxial compression and four point bending tests on silicone rubber shells with and without compliant foam cores. The analysis describes the results of the mechanical tests well. Characterization of the microstructures of several natural tubular structures with foamlike cores (plant stems, quills, and spines) revealed them to be close to the optimal configurations predicted by the analytical model. Biomimicking of natural cylindrical shell structures and evolutionary design processes may offer the potential to increase the mechanical efficiency of engineering cylindrical shells.

  20. Broadband absorption and enhanced photothermal conversion property of octopod-like Ag@Ag2S core@shell structures with gradually varying shell thickness.

    Science.gov (United States)

    Jiang, Qian; Zeng, Wenxia; Zhang, Canying; Meng, Zhaoguo; Wu, Jiawei; Zhu, Qunzhi; Wu, Daxiong; Zhu, Haitao

    2017-12-19

    Photothermal conversion materials have promising applications in many fields and therefore they have attracted tremendous attention. However, the multi-functionalization of a single nanostructure to meet the requirements of multiple photothermal applications is still a challenge. The difficulty is that most nanostructures have specific absoprtion band and are not flexible to different demands. In the current work, we reported the synthesis and multi-band photothermal conversion of Ag@Ag 2 S core@shell structures with gradually varying shell thickness. We synthesized the core@shell structures through the sulfidation of Ag nanocubes by taking the advantage of their spatially different reactivity. The resulting core@shell structures show an octopod-like mopgorlogy with a Ag 2 S bulge sitting at each corner of the Ag nanocubes. The thickness of the Ag 2 S shell gradually increases from the central surface towards the corners of the structure. The synthesized core@shell structures show a broad band absorption spectrum from 300 to 1100 nm. Enhanced photothermal conversion effect is observed under the illuminations of 635, 808, and 1064 nm lasers. The results indicate that the octopod-like Ag@Ag 2 S core@shell structures have characteristics of multi-band photothermal conversion. The current work might provide a guidance for the design and synthesis of multifunctional photothermal conversion materials.

  1. Electronic structure of CdTe using GGA+USIC

    International Nuclear Information System (INIS)

    Menéndez-Proupin, E.; Amézaga, A.; Cruz Hernández, N.

    2014-01-01

    A simple method to obtain a gap-corrected band structure of cadmium telluride within density functional theory is presented. On-site Coulomb self-interaction-like correction potential has been applied to the 5p-shell of Te and the 4d-shell of Cd. The predicted physical properties are similar to or better than those obtained with hybrid functionals and at largely reduced computational cost. In addition to the corrected electronic structure, the lattice parameters and the bulk modulus are improved. The relative stabilities of the different phases (zincblende, wurtzite, rocksalt and cinnabar) are preserved. The formation energy of the cadmium vacancy remains close to the values obtained from hybrid functional calculations

  2. Direct correlations of structural and optical properties of three-dimensional GaN/InGaN core/shell micro-light emitting diodes

    Science.gov (United States)

    Sadat Mohajerani, Matin; Müller, Marcus; Hartmann, Jana; Zhou, Hao; Wehmann, Hergo-H.; Veit, Peter; Bertram, Frank; Christen, Jürgen; Waag, Andreas

    2016-05-01

    Three-dimensional (3D) InGaN/GaN quantum-well (QW) core-shell light emitting diodes (LEDs) are a promising candidate for the future solid state lighting. In this contribution, we study direct correlations of structural and optical properties of the core-shell LEDs using highly spatially-resolved cathodoluminescence spectroscopy (CL) in combination with scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM). Temperature-dependent resonant photoluminescence (PL) spectroscopy has been performed to understand recombination mechanisms and to estimate the internal quantum efficiency (IQE).

  3. A study on the nonlinear finite element analysis of reinforced concrete structures: shell finite element formulation

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang Jin; Seo, Jeong Moon

    2000-08-01

    The main goal of this research is to establish a methodology of finite element analysis of containment building predicting not only global behaviour but also local failure mode. In this report, we summerize some existing numerical analysis techniques to be improved for containment building. In other words, a complete description of the standard degenerated shell finite element formulation is provided for nonlinear stress analysis of nuclear containment structure. A shell finite element is derived using the degenerated solid concept which does not rely on a specific shell theory. Reissner-Mindlin assumptions are adopted to consider the transverse shear deformation effect. In order to minimize the sensitivity of the constitutive equation to structural types, microscopic material model is adopted. The four solution algorithms based on the standard Newton-Raphson method are discussed. Finally, two numerical examples are carried out to test the performance of the adopted shell medel.

  4. A study on the nonlinear finite element analysis of reinforced concrete structures: shell finite element formulation

    International Nuclear Information System (INIS)

    Lee, Sang Jin; Seo, Jeong Moon

    2000-08-01

    The main goal of this research is to establish a methodology of finite element analysis of containment building predicting not only global behaviour but also local failure mode. In this report, we summerize some existing numerical analysis techniques to be improved for containment building. In other words, a complete description of the standard degenerated shell finite element formulation is provided for nonlinear stress analysis of nuclear containment structure. A shell finite element is derived using the degenerated solid concept which does not rely on a specific shell theory. Reissner-Mindlin assumptions are adopted to consider the transverse shear deformation effect. In order to minimize the sensitivity of the constitutive equation to structural types, microscopic material model is adopted. The four solution algorithms based on the standard Newton-Raphson method are discussed. Finally, two numerical examples are carried out to test the performance of the adopted shell medel

  5. Mass spectrometric identification of Au68(SR)34 molecular gold nanoclusters with 34-electron shell closing.

    Science.gov (United States)

    Dass, Amala

    2009-08-26

    The molecular formula Au(68)(SCH(2)CH(2)Ph)(34) has been assigned to the 14 kDa nanocluster using MALDI-TOF mass spectrometry. The 34-electron shell closing in a macroscopically obtained thiolated gold nanocluster is demonstrated. The Au(68) nanocluster is predicted to have a 49 atom Marks decahedral core with 19 inner core atoms and 30 outer atoms chelating with the staple motifs. The nanoclusters' predicted formulation is [Au](19+30) [Au(SR)(2)](11) [Au(2)(SR)(3)](4).

  6. Onion-shell model for cosmic ray electrons and radio synchrotron emission in supernova remnants

    International Nuclear Information System (INIS)

    Beck, R.; Drury, L.O.; Voelk, H.J.; Bogdan, T.J.

    1985-01-01

    The spectrum of cosmic ray electrons, accelerated in the shock front of a supernova remnant (SNR), is calculated in the test-particle approximation using an onion-shell model. Particle diffusion within the evolving remnant is explicity taken into account. The particle spectrum becomes steeper with increasing radius as well as SNR age. Simple models of the magnetic field distribution allow a prediction of the intensity and spectrum of radio synchrotron emission and their radial variation. The agreement with existing observations is satisfactory in several SNR's but fails in other cases. Radiative cooling may be an important effect, especially in SNR's exploding in a dense interstellar medium

  7. Onion-shell model for cosmic ray electrons and radio synchrotron emission in supernova remnants

    Science.gov (United States)

    Beck, R.; Drury, L. O.; Voelk, H. J.; Bogdan, T. J.

    1985-01-01

    The spectrum of cosmic ray electrons, accelerated in the shock front of a supernova remnant (SNR), is calculated in the test-particle approximation using an onion-shell model. Particle diffusion within the evolving remnant is explicity taken into account. The particle spectrum becomes steeper with increasing radius as well as SNR age. Simple models of the magnetic field distribution allow a prediction of the intensity and spectrum of radio synchrotron emission and their radial variation. The agreement with existing observations is satisfactory in several SNR's but fails in other cases. Radiative cooling may be an important effect, especially in SNR's exploding in a dense interstellar medium.

  8. Electronic structure of lanthanide scandates

    Science.gov (United States)

    Mizzi, Christopher A.; Koirala, Pratik; Marks, Laurence D.

    2018-02-01

    X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and density functional theory calculations were used to study the electronic structure of three lanthanide scandates: GdSc O3,TbSc O3 , and DySc O3 . X-ray photoelectron spectra simulated from first-principles calculations using a combination of on-site hybrid and GGA +U methods were found to be in good agreement with experimental x-ray photoelectron spectra. The hybrid method was used to model the ground state electronic structure and the GGA +U method accounted for the shift of valence state energies due to photoelectron emission via a Slater-Janak transition state approach. From these results, the lanthanide scandate valence bands were determined to be composed of Ln 4 f ,O 2 p , and Sc 3 d states, in agreement with previous work. However, contrary to previous work the minority Ln 4 f states were found to be located closer to, and in some cases at, the valence band maximum. This suggests that minority Ln 4 f electrons may play a larger role in lanthanide scandate properties than previously thought.

  9. Investigation of CuInSe2 nanowire arrays with core-shell structure electrodeposited at various duty cycles into anodic alumina templates

    Science.gov (United States)

    Cheng, Yu-Song; Wang, Na-Fu; Tsai, Yu-Zen; Lin, Jia-Jun; Houng, Mau-Phon

    2017-02-01

    Copper indium selenide (CuInSe2) nanowire (NW) arrays were prepared at various electrolyte duty cycles by filling anodic alumina templates through the pulsed electrodeposition technique. X-ray diffraction and scanning electron microscopy (SEM) images showed that the nucleation mechanism of CuInSe2 NW arrays was affected by the electrodeposition duty cycle. Moreover, SEM images showed that the diameter and length of the NWs were 80 nm and 2 μm, respectively. Furthermore, PEDOT/CuInSe2 NW core-shell arrays were fabricated using surfactant-modified CuInSe2 NW surfaces showing the lotus effect. Transmission electron microscopy images confirmed that a core-shell structure was achieved. Current-voltage plots revealed that the CuInSe2 NW arrays were p-type semiconductors; moreover, the core-shell structure improved the diode ideality factor from 3.91 to 2.63.

  10. Supercooling suppression of microencapsulated phase change materials by optimizing shell composition and structure

    International Nuclear Information System (INIS)

    Cao, Fangyu; Yang, Bao

    2014-01-01

    Highlights: • A new method for supercooling suppression of microPCMs by optimizing the structure of the microcapsule shell. • Large effective latent heat (up to 213 J/g) of the microPCMs, much higher than those using additive as nucleating agents. • Change of shell composition and structure significantly affects the phase transition processes of the encapsulated PCMs. • The latent heat of the shell-induced phase transition is maximized, reaching 83.7% of the latent heat of bulk octadecane. • Hollow spheres with porous rather than solid resin shell are also formed when the SDS concentration is very high. - Abstract: A new method for supercooling suppression of microencapsulated phase change materials (PCMs) has been developed by optimizing the composition and structure of the microcapsule resin shell. The microcapsules comprising paraffin octadecane encapsulated in melamine–formaldehyde resin shell were synthesized with the use the oil-in-water emulsion technique. These PCM microcapsules are 5–15 μm in diameter. The supercooling of these octadecane microcapsules can be as large as 13.6 °C, when the homogeneous nucleation is dominant during the melt crystallization into the thermodynamically stable triclinic phase. It is discovered that the homogeneous nucleation can be mediated by shell-induced nucleation of the triclinic phase and the metastable rotator phase when the shell composition and structure are optimized, without need of any nucleating additives. The effects of synthesis parameters, such as ratio of melamine to formaldehyde, pH of pre-polymer, and pH of emulsion, on the phase transition properties of the octadecane microcapsules have been investigated systemically. The optimum synthesis conditions have been identified in terms of minimizing the supercooling while maintaining heat capacity. Potential applications of this type of phase changeable microcapsules include high heat capacity thermal fluids, thermal management in smart buildings

  11. Structural Color Palettes of Core-Shell Photonic Ink Capsules Containing Cholesteric Liquid Crystals.

    Science.gov (United States)

    Lee, Sang Seok; Seo, Hyeon Jin; Kim, Yun Ho; Kim, Shin-Hyun

    2017-06-01

    Photonic microcapsules with onion-like topology are microfluidically designed to have cholesteric liquid crystals with opposite handedness in their core and shell. The microcapsules exhibit structural colors caused by dual photonic bandgaps, resulting in a rich variety of color on the optical palette. Moreover, the microcapsules can switch the colors from either core or shell depending on the selection of light-handedness. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Economic Development through Globalisation in Nigeria : An analysis of Shell & the IMF Structural Adjustment Programs

    OpenAIRE

    Bokhari, Sven; Del Duca, Fabrizio

    2008-01-01

    Date: 2008/06/03 Level: Master thesis in International Business and Entrepreneurship, 10p (15ECTS) Authors: Sven Bokhari Fabrizio Del Duca Title: Economic Development through globalisation in Nigeria. An analysis of Shell & the IMF Structural Adjustment Programs Tutor: Leif Linnskog, Ph.D. Research Question: Can globalisation be seen as positive or negative for the Economic Development of Nigeria? A focus on Shell and the International Monetary Fund Research Issue: Globalisation in its cu...

  13. Subshell resolved L shell ionization of Bi and U induced by 16 - 45 keV electrons

    International Nuclear Information System (INIS)

    Rahangdale, Hitesh; Das, Pradipta K.; Saha, S.; Mitra, D.

    2015-01-01

    Electron induced inner-shell ionization is important for both fundamental and applied research. Ionization of outer atomic energy levels has been studied extensively than for inner levels. Knowledge of inner shell ionization cross sections is important in X-ray and Auger electron spectroscopy and in the fields of astrophysics, plasma physics, surface science and many more. At electron impact energies near the atomic binding energies the distortion of the wave functions from plane wave towards a spherical wave, due to the electrostatic field of the atoms, needs to be considered. The distorted wave Born approximation (DWBA) calculations, taking relativistic effects and exchange interaction into account, is used to estimate the K, L and M-shell ionization cross-section for the atoms. Earlier experiments on electron impact ionization studies focused mainly on K-shell ionization cross-section, while L and M-shell ionization data were hardly reported. A review of the existing L-shell ionization cross-section data shows that, while the X-ray production cross-sections by electron impact were reported quite a few times, the reporting of subshell resolved ionization cross-sections were rarely found near the ionization threshold region. In the present work, we have measured the X ray production cross-sections of different L lines of Bi and U induced by 16-45 keV electrons and converted the obtained values to the subshell specific ionization cross-sections. The experimental data are compared with the theoretical calculations based on the (DWBA) obtained from PENELOPE. To the best of our knowledge, the subshell resolved electron induced ionization cross-sections for the L-shell of Bi and U are reported here for the first time at the energy values near the corresponding ionization threshold. (author)

  14. Structure of natural draft cooling towers, 1. Study on cooling tower shells

    Energy Technology Data Exchange (ETDEWEB)

    Ishioka, H; Sakamoto, Y; Tsurusaki, M; Koshizawa, K; Chiba, T [Ishikawajima-Harima Heavy Industries Co. Ltd., Tokyo (Japan)

    1976-09-01

    Recently in Japan, demands for cooling tower systems have been increasing remarkably with the construction of large power plants and the legislation of environmental regulations. In view of the severe natural conditions in Japan such as strong wind and seismic loadings, etc., the establishment of the optimum design and construction method is essential for the building of safe and economical towers. In order to establish a comprehensive plan of a power plant cooling system of the appropriate structural type, the authors have made researches and experiments on design conditions, static and dynamic analyses, and comparative studies of various structural types such as reinforced concrete thin-shell structures, steel framed structures and composite shell segment structures, based on the investigation results of towers in Europe and America. These results are presented in three reports, the 1st of which concerns cooling tower shells as are herein described.

  15. Ductile all-cellulose nanocomposite films fabricated from core-shell structured cellulose nanofibrils.

    Science.gov (United States)

    Larsson, Per A; Berglund, Lars A; Wågberg, Lars

    2014-06-09

    Cellulosic materials have many desirable properties such as high mechanical strength and low oxygen permeability and will be an important component in a sustainable biomaterial-based society, but unfortunately they often lack the ductility and formability offered by petroleum-based materials. This paper describes the fabrication and characterization of nanocomposite films made of core-shell modified cellulose nanofibrils (CNFs) surrounded by a shell of ductile dialcohol cellulose, created by heterogeneous periodate oxidation followed by borohydride reduction of the native cellulose in the external parts of the individual fibrils. The oxidation with periodate selectively produces dialdehyde cellulose, and the process does not increase the charge density of the material. Yet the modified cellulose fibers could easily be homogenized to CNFs. Prior to film fabrication, the CNF was shown by atomic force microscopy to be 0.5-2 μm long and 4-10 nm wide. The films were fabricated by filtration, and besides uniaxial tensile testing at different relative humidities, they were characterized by scanning electron microscopy and oxygen permeability. The strength-at-break at 23 °C and 50% RH was 175 MPa, and the films could, before rupture, be strained, mainly by plastic deformation, to about 15% and 37% at 50% RH and 90% RH, respectively. This moisture plasticization was further utilized to form a demonstrator consisting of a double-curved structure with a nominal strain of 24% over the curvature. At a relative humidity of 80%, the films still acted as a good oxygen barrier, having an oxygen permeability of 5.5 mL·μL/(m(2)·24 h·kPa). These properties indicate that this new material has a potential for use as a barrier in complex-shaped structures and hence ultimately reduce the need for petroleum-based plastics.

  16. Coercivity enhancement in Ce-Fe-B based magnets by core-shell grain structuring

    Directory of Open Access Journals (Sweden)

    M. Ito

    2016-05-01

    Full Text Available Ce-based R2Fe14B (R= rare-earth nano-structured permanent magnets consisting of (Ce,Nd2Fe14B core-shell grains separated by a non-magnetic grain boundary phase, in which the relative amount of Nd to Ce is higher in the shell of the magnetic grain than in its core, were fabricated by Nd-Cu infiltration into (Ce,Nd2Fe14B hot-deformed magnets. The coercivity values of infiltrated core-shell structured magnets are superior to those of as-hot-deformed magnets with the same overall Nd content. This is attributed to the higher value of magnetocrystalline anisotropy of the shell phase in the core-shell structured infiltrated magnets compared to the homogeneous R2Fe14B grains of the as-hot-deformed magnets, and to magnetic isolation of R2Fe14B grains by the infiltrated grain boundary phase. First order reversal curve (FORC diagrams suggest that the higher anisotropy shell suppresses initial magnetization reversal at the edges and corners of the R2Fe14B grains.

  17. Synthesis, structural characterization and dielectric properties of Nb doped BaTiO3/SiO2 core–shell heterostructure

    International Nuclear Information System (INIS)

    Cernea, M.; Vasile, B.S.; Boni, A.; Iuga, A.

    2014-01-01

    Highlights: • Optimal parameters for preparation by sol–gel of core–shell (BT-Nb 0.005 )/SiO 2 are presented in this paper. • Single crystalline BT-Nb 0.005 /SiO 2 core–shell composite with ∼34 nm shell thick was prepared. • The core–shell ceramic exhibits good dielectric properties and ferroelectric characteristics. -- Abstract: Perovskite complex ceramic oxides, BaTiO 3 doped with 0.5 mol%Nb 2 O 5 and then nanocoated with SiO 2 (abbreviated as BT-Nb 0.005 /SiO 2 ) was successful prepared using conventional sol–gel processing. Phase composition, particle morphology, structure, and electric properties of BT-Nb 0.005 core and BT-Nb 0.005 /SiO 2 core–shell were examined and compared, using X-ray diffraction, transmission electron microscopy and, dielectric and ferroelectric measurements. Core–shell composite with well-defined perovskite tetragonal phase of BaTiO 3 was achieved. Furthermore, single crystalline BT-Nb 0.005 /SiO 2 core–nanoshell heterostructure with ∼34 nm shell thick was prepared, which is a novelty in ferroelectrics field. The ferroelectric quality of BT-Nb 0.005 has suffered an alteration when the (BT-Nb 0.005 )/SiO 2 core–shell heterostructure was realized. One-dimensional BT-Nb 0.005 /SiO 2 core–shell heterostructure exhibits an improvement of dielectric losses and a decrease of dielectric constant, compared to uncoated BT-Nb 0.005 . The (BT-Nb 0.005 )/SiO 2 core–shell material could be interesting for application in the composite capacitors

  18. Delta electron spectroscopy for the study of the inner-shell excitation in heavy ion collisions

    International Nuclear Information System (INIS)

    Trollmann, G.

    1981-01-01

    In this thesis energy and angular differential cross sections of delta electrons from ion-atom collisions are measured and compared with different perturbation theories. Shell specific cross sections were obtained from electron-X-ray coincidences. Contradicting theoretical statements concerning the angular distribution of the electrons can be experimentally clarified, other predictions are verified. Starting from fast, strongly asymmetric collisions until to slow, more symmetric collisions the question of the disturbance of the stationary target state by the projectile and the formation of intermediate molecular state is studied. With the results of the measurement of the delta electrons it can be contributed to the clarification of the question for the physical origin of the continuous X-radiation in the energy range beyond the K-line of the heavier collision partner. It is shown that the secondary electron bremsstrahlung discussed as radiation source besides the molecular orbital (MO) radiation is in its intensity about more than one order of magnitude weaker than the measured X-radiation and is therefore excluded as dominant radiation. In the framework of this work an apparature was developed, which allows the electron spectroscopy in the energy range between 10 keV and 150 keV and the angular range between 5 degrees and 180 degrees for the absolute determination of double differential cross sections. (orig./HSI) [de

  19. Understanding the Thermal Stability of Palladium-Platinum Core-Shell Nanocrystals by In Situ Transmission Electron Microscopy and Density Functional Theory.

    Science.gov (United States)

    Vara, Madeline; Roling, Luke T; Wang, Xue; Elnabawy, Ahmed O; Hood, Zachary D; Chi, Miaofang; Mavrikakis, Manos; Xia, Younan

    2017-05-23

    Core-shell nanocrystals offer many advantages for heterogeneous catalysis, including precise control over both the surface structure and composition, as well as reduction in loading for rare and costly metals. Although many catalytic processes are operated at elevated temperatures, the adverse impacts of heating on the shape and structure of core-shell nanocrystals are yet to be understood. In this work, we used ex situ heating experiments to demonstrate that Pd@Pt 4L core-shell nanoscale cubes and octahedra are promising for catalytic applications at temperatures up to 400 °C. We also used in situ transmission electron microscopy to monitor the thermal stability of the core-shell nanocrystals in real time. Our results demonstrate a facet dependence for the thermal stability in terms of shape and composition. Specifically, the cubes enclosed by {100} facets readily deform shape at a temperature 300 °C lower than that of the octahedral counterparts enclosed by {111} facets. A reversed trend is observed for composition, as alloying between the Pd core and the Pt shell of an octahedron occurs at a temperature 200 °C lower than that for the cubic counterpart. Density functional theory calculations provide atomic-level explanations for the experimentally observed behaviors, demonstrating that the barriers for edge reconstruction determine the relative ease of shape deformation for cubes compared to octahedra. The opposite trend for alloying of the core-shell structure can be attributed to a higher propensity for subsurface Pt vacancy formation in octahedra than in cubes.

  20. Electron scattering and nuclear structure

    International Nuclear Information System (INIS)

    Frois, B.

    1987-01-01

    The search for the appropriate degrees of freedom to describe nuclei is the central focus of nuclear physics today. Therefore the authors explore in this review their current understanding of nuclear structure as defined by electromagnetic data. The precision of the electromagnetic probe allows us to define accurately the limits of present theoretical descriptions. The authors review here a broad range of subjects that have been addressed by recent experiments, from the study of meson exchange currents and single-particle distributions to collective excitations in heavy nuclei. However, they do not discuss elastic magnetic scattering, inelastic excitation of discrete states, or single-nucleon knockout reactions since these reactions were recently reviewed. The principal aim of this review is to offer a fresh perspective on nuclear structure, based on the new generation of electron scattering data presented here and in the above-mentioned articles

  1. Electronic Structure of GdCuGe Intermetallic Compound

    Science.gov (United States)

    Lukoyanov, A. V.; Knyazev, Yu. V.; Kuz'min, Yu. I.

    2018-04-01

    The electronic structure of GdCuGe intermetallic compound has been studied. Spin-polarized energy spectrum calculations have been performed by the band method with allowance for strong electron correlations in the 4 f-shell of gadolinium ions. Antiferromagnetic ordering of GdCuGe at low temperatures has been obtained in a theoretical calculation, with the value of the effective magnetic moment of gadolinium ions reproduced in fair agreement with experimental data. The electronic density of states has been analyzed. An optical conductivity spectrum has been calculated for GdCuGe; it reveals specific features that are analogous to the ones discovered previously in the GdCuSi compound with a similar hexagonal structure.

  2. High spin structure of {sup 35}Cl and the sd-fp shell gap

    Energy Technology Data Exchange (ETDEWEB)

    Kshetri, Ritesh [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Saha Sarkar, M. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India)]. E-mail: maitrayee.sahasarkar@saha.ac.in; Ray, Indrani [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Banerjee, P. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Sarkar, S. [Department of Physics, Bengal Engineering and Science University, Shibpur, Howrah 711103 (India); Raut, Rajarshi [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Goswami, A. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Chatterjee, J.M. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Chattopadhyay, S. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Datta Pramanik, U. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Mukherjee, A. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Dey, C.C. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Bhattacharya, S. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Dasmahapatra, B. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Bhowal, Samit [Department of Physics, Surendranath Evening College, Kolkata 700009 (India); Gangopadhyay, G. [University of Calcutta, 92, Acharya Prafulla Chandra Road, Kolkata 700009 (India); Datta, P. [Anandamohan College, 102/1, Raja Rammohan Sarani, Kolkata 700009 (India); Jain, H.C. [Tata Institute of Fundamental Research, Mumbai 400005 (India); Bhowmik, R.K. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Muralithar, S.; Singh, R.P.; Kumar, R. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India)

    2007-01-15

    The high spin states of {sup 35}Cl have been studied by in-beam {gamma}-spectroscopy following the fusion-evaporation reaction {sup 12}C({sup 28}Si,{alpha}p){sup 35}Cl at E{sub lab}=70 and 88 MeV, using the Indian National Gamma (Clover) Array (INGA). Lifetimes of six new excited states have been estimated for the first time. To understand the underlying structure of the levels and transition mechanisms, experimental results have been compared with those from the large basis cross-shell shell model calculations. Involvement of orbitals from fp shell and squeezing of the sd-fp shell gap seem to be essential for reliable reproduction of high spin states.

  3. High spin structure of 35Cl and the sd-fp shell gap

    International Nuclear Information System (INIS)

    Kshetri, Ritesh; Saha Sarkar, M.; Ray, Indrani; Banerjee, P.; Sarkar, S.; Raut, Rajarshi; Goswami, A.; Chatterjee, J.M.; Chattopadhyay, S.; Datta Pramanik, U.; Mukherjee, A.; Dey, C.C.; Bhattacharya, S.; Dasmahapatra, B.; Bhowal, Samit; Gangopadhyay, G.; Datta, P.; Jain, H.C.; Bhowmik, R.K.; Muralithar, S.; Singh, R.P.; Kumar, R.

    2007-01-01

    The high spin states of 35 Cl have been studied by in-beam γ-spectroscopy following the fusion-evaporation reaction 12 C( 28 Si,αp) 35 Cl at E lab =70 and 88 MeV, using the Indian National Gamma (Clover) Array (INGA). Lifetimes of six new excited states have been estimated for the first time. To understand the underlying structure of the levels and transition mechanisms, experimental results have been compared with those from the large basis cross-shell shell model calculations. Involvement of orbitals from fp shell and squeezing of the sd-fp shell gap seem to be essential for reliable reproduction of high spin states

  4. Surface energy effect on free vibration of nano-sized piezoelectric double-shell structures

    Science.gov (United States)

    Fang, Xue-Qian; Zhu, Chang-Song; Liu, Jin-Xi; Liu, Xiang-Lin

    2018-01-01

    Combining Goldenveizer-Novozhilov shell theory, thin plate theory and electro-elastic surface theory, the size-dependent vibration of nano-sized piezoelectric double-shell structures under simply supported boundary condition is presented, and the surface energy effect on the natural frequencies is discussed. The displacement components of the cylindrical nano-shells and annular nano-plates are expanded as the superposition of standard Fourier series based on Hamilton's principle. The total stresses with consideration of surface energy effect are derived, and the total energy function is obtained by using Rayleigh-Ritz energy method. The free vibration equation is solved, and the natural frequency is analyzed. In numerical examples, it is found that the surface elastic constant, piezoelectric constant and surface residual stress show different effects on the natural frequencies. The effect of surface piezoelectric constant is the maximum. The effect of dimensions of the double-shell under different surface material properties is also examined.

  5. Quantum electrodynamic corrections for the valence shell in heavy many-electron atoms

    International Nuclear Information System (INIS)

    Thierfelder, C.; Schwerdtfeger, P.

    2010-01-01

    We present quantum electrodynamic (QED) calculations within the picture of bound-state QED for the frequency-dependent Breit interaction between electrons, the vacuum polarization, and the electron self-energy correction starting from the Dirac-Coulomb Hamiltonian for the ionization potentials of the group 1, 2, 11, 12, 13, and 18 elements of the periodic table, and down to the superheavy elements up to nuclear charge Z=120. The results for the s-block elements are in very good agreement with earlier studies by Labzowsky et al. [Phys. Rev. A 59, 2707 (1999)]. We discuss the influence of the variational versus perturbative treatment of the Breit interaction for valence-space ionization potentials. We argue that the lowest-order QED contributions become as important as the Breit interaction for ionization potentials out of the valence s shell.

  6. Assembly and luminescence properties of lanthanide-polyoxometalates/polyethyleneimine/SiO{sub 2} particles with core–shell structure

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jun, E-mail: junwang924@yahoo.com.cn; Fan, Shaohua; Zhao, Weiqian; Zhang, Hongyan

    2013-01-01

    In this paper, two lanthanide-polyoxometalate (LnW{sub 10}) complexes were bonded on the surface of the polyethyleneimine (PEI)-modified silica nanoparticles with different sizes, resulting in the formation of LnW{sub 10}/PEI/SiO{sub 2} particles. The hybrid core–shell particles were characterized by infrared, luminescent spectra, scanning electronic microscope, and transmission electronic microscope. The particles obtained exhibit the fine spherical core–shell structure and the excellent luminescence properties. The luminescence spectra studies revealed that the formation of LnW{sub 10}/PEI/SiO{sub 2} particles and the size of particle have an influence on the luminescence properties of lanthanide ions. - Highlights: ► SiO{sub 2}/polyethyleneimine (PEI) shows the chemisorption for Ln-polyoxometalates (LnW{sub 10}). ► The core-shell LnW{sub 10}/PEI/SiO{sub 2} nanoparticles with different sizes were fabricated. ► The hybrid particles exhibit the excellent luminescence properties. ► The sizes of particles affect the luminescence properties of lanthanide ions.

  7. Zero-valent iron treatment of dark brown colored coffee effluent: Contributions of a core-shell structure to pollutant removals.

    Science.gov (United States)

    Tomizawa, Mayuka; Kurosu, Shunji; Kobayashi, Maki; Kawase, Yoshinori

    2016-12-01

    The decolorization and total organic carbon (TOC) removal of dark brown colored coffee effluent by zero-valent iron (ZVI) have been systematically examined with solution pH of 3.0, 4.0, 6.0 and 8.0 under oxic and anoxic conditions. The optimal decolorization and TOC removal were obtained at pH 8.0 with oxic condition. The maximum efficiencies of decolorization and TOC removal were 92.6 and 60.2%, respectively. ZVI presented potential properties for pollutant removal at nearly neutral pH because of its core-shell structure in which shell or iron oxide/hydroxide layer on ZVI surface dominated the decolorization and TOC removal of coffee effluent. To elucidate the contribution of the core-shell structure to removals of color and TOC at the optimal condition, the characterization of ZVI surface by scanning electron microscopy (SEM) with an energy dispersive X-ray spectroscope (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) was conducted. It was confirmed that the core-shell structure was formed and the shell on ZVI particulate surface and the precipitates formed during the course of ZVI treatment consisted of iron oxides and hydroxides. They were significantly responsible for decolorization and TOC removal of coffee effluent via adsorption to shell on ZVI surface and inclusion into the precipitates rather than the oxidative degradation by OH radicals and the reduction by emitted electrons. The presence of dissolved oxygen (DO) enhanced the formation of the core-shell structure and as a result improved the efficiency of ZVI treatment for the removal of colored components in coffee effluents. ZVI was found to be an efficient material toward the treatment of coffee effluents. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Synthesis of novel core-shell structured dual-mesoporous silica nanospheres and their application for enhancing the dissolution rate of poorly water-soluble drugs

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Chao, E-mail: wuchao27@126.com [Department of Pharmaceutics, Liaoning Medical University, 40 Songpo Road, Linghe District, Jinzhou, Liaoning Province 121001 (China); Sun, Xiaohu [Management Center for Experiments, Bohai University, 19 Keji Road, Songshan District, Jinzhou, Liaoning Province 121000 (China); Zhao, Zongzhe; Zhao, Ying; Hao, Yanna; Liu, Ying [Department of Pharmaceutics, Liaoning Medical University, 40 Songpo Road, Linghe District, Jinzhou, Liaoning Province 121001 (China); Gao, Yu, E-mail: gaoyu_1116@163.com [Department of Medical Oncology, First Affiliated Hospital of Liaoning Medical University, 40 Songpo Road, Linghe District, Jinzhou, Liaoning Province 121001 (China)

    2014-11-01

    Novel core-shell dual-mesoporous silica nanospheres (DMSS) with a tunable pore size were synthesized successfully using a styrene monomer as a channel template for the core and cetyltrimethyl ammonium bromide (CTAB) as a channel template for the shell in order to improve the dissolution rate of poorly water-soluble drugs. Simvastatin was used as a model drug and loaded into DMSS and the mesoporous core without the shell (MSC) by the solvent evaporation method. The drug loading efficiency of DMSS and MSC were determined by thermogravimetric analysis (TGA) and ultraviolet spectroscopy (UV). Characterization, using scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption, powder X-ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR) showed that simvastatin adsorbed in DMSS and MSC was in an amorphous state, and in vitro release test results demonstrated that both DMSS and MSC increased the water solubility and dissolution rate of simvastatin. The shell structure of DMSS was able to regulate the release of simvastatin compared with MSC. It is worth noting that DMSS has significant potential as a carrier for improving the dissolution of poorly water-soluble drugs and reducing the rapid release. - Highlights: • A novel core-shell DMSS is prepared for improving the dissolution rate of simvastatin. • The diffusional resistance of the mesoporous shell can delay and regulate drug release. • Simvastatin absorbed in DMSS exists in amorphous form due to spatial confinement.

  9. Synthesis of novel core-shell structured dual-mesoporous silica nanospheres and their application for enhancing the dissolution rate of poorly water-soluble drugs

    International Nuclear Information System (INIS)

    Wu, Chao; Sun, Xiaohu; Zhao, Zongzhe; Zhao, Ying; Hao, Yanna; Liu, Ying; Gao, Yu

    2014-01-01

    Novel core-shell dual-mesoporous silica nanospheres (DMSS) with a tunable pore size were synthesized successfully using a styrene monomer as a channel template for the core and cetyltrimethyl ammonium bromide (CTAB) as a channel template for the shell in order to improve the dissolution rate of poorly water-soluble drugs. Simvastatin was used as a model drug and loaded into DMSS and the mesoporous core without the shell (MSC) by the solvent evaporation method. The drug loading efficiency of DMSS and MSC were determined by thermogravimetric analysis (TGA) and ultraviolet spectroscopy (UV). Characterization, using scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption, powder X-ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR) showed that simvastatin adsorbed in DMSS and MSC was in an amorphous state, and in vitro release test results demonstrated that both DMSS and MSC increased the water solubility and dissolution rate of simvastatin. The shell structure of DMSS was able to regulate the release of simvastatin compared with MSC. It is worth noting that DMSS has significant potential as a carrier for improving the dissolution of poorly water-soluble drugs and reducing the rapid release. - Highlights: • A novel core-shell DMSS is prepared for improving the dissolution rate of simvastatin. • The diffusional resistance of the mesoporous shell can delay and regulate drug release. • Simvastatin absorbed in DMSS exists in amorphous form due to spatial confinement

  10. Electronic structure of spin systems

    Energy Technology Data Exchange (ETDEWEB)

    Saha-Dasgupta, Tanusri

    2016-04-15

    Highlights: • We review the theoretical modeling of quantum spin systems. • We apply the Nth order muffin-tin orbital electronic structure method. • The method shows the importance of chemistry in the modeling. • CuTe{sub 2}O{sub 5} showed a 2-dimensional coupled spin dimer behavior. • Ti substituted Zn{sub 2}VO(PO{sub 4}){sub 2} showed spin gap behavior. - Abstract: Low-dimensional quantum spin systems, characterized by their unconventional magnetic properties, have attracted much attention. Synthesis of materials appropriate to various classes within these systems has made this field very attractive and a site of many activities. The experimental results like susceptibility data are fitted with the theoretical model to derive the underlying spin Hamiltonian. However, often such a fitting procedure which requires correct guess of the assumed spin Hamiltonian leads to ambiguity in deciding the representative model. In this review article, we will describe how electronic structure calculation within the framework of Nth order muffin-tin orbital (NMTO) based Wannier function technique can be utilized to identify the underlying spin model for a large number of such compounds. We will show examples from compounds belonging to vanadates and cuprates.

  11. Studies in the electronic structure of matter

    International Nuclear Information System (INIS)

    Swarts, C.A.

    1979-01-01

    Chapter I: Here the results of various theories for the angular distribution of electrons photoemitted from the outermost p-shell of rare gas atoms are compared. The theories compared are (I) the local density theories of Slater (X/sub α/) and of Hohenberg, Kohn and Sham, (II) the pseudopotential method, (III) Hartree-Fock theory as evaluated by Kennedy and Manson, and (IV) Amusia's Random Phase Approximation with Exchange (RPAE). It is shown that the local density theories, although simple, generally fail to produce reliable cross section; the more complicated Hartree-Fock method is no more reliable; the a priori RPAE method is most reliable, but tedious; and the phenomenological pseudopotential method offers a good combination of reliability and simplicity. The muffin-tin approximation, widely used in molecular and condensed matter physics, is examined and found to be adequate. Chapter II: Extended Hueckel theory is applied to GaAs, GaP and to the nitrogen isoelectronic trap in GaAs and GaP. The computed perfect crystal band structures are found to be in reasonable agreement with those computed with empirical pseudopotentials. Nitrogen impurity levels in GaAs and GaP are calculated using a cluster model. Chapter III: By means of model calculations for an independent electron metal, we obtain exact lineshapes for the photon absorption, emission and photoemission spectra of deep core states. We find in each case an X-ray edge anomaly as pedicted by Nozieres and De Dominicis. Sumrules are used as a general check on the calculations and to explain the deviations of the exact theory from the exciton theory away from threshold

  12. Shell structure at high spin and the influence on nuclear shapes

    International Nuclear Information System (INIS)

    Khoo, T.L.; Chowdhury, P.; Ahmad, I.

    1982-01-01

    Nuclear structure at high spin is influenced by a combination of liquid-drop and shell-structure effects. For N 90. The competition between oblate and prolate driving effects leads to a prolate-to-oblate shape transition in 154 Dy 88 . The role of rotation-aligned configurations in the shape change is discussed

  13. Probing the Evolution of the Shell Structures in Exotic Nuclei

    International Nuclear Information System (INIS)

    De Angelis, Giacomo

    2008-01-01

    Magic numbers are a key feature in finite Fermion systems since they are strongly related to the underlying mean field. The size of the shell gaps and their evolution far from stability can be linked to the shape and symmetry of the nuclear mean field. Moreover the study of nuclei with large neutron/proton ratio allow to probe the density dependence of the effective interaction. Changes of the nuclear density and size in nuclei with increasing N/Z ratios are expected to lead to different nuclear symmetries and excitations. In this contribution I will discuss some selected examples which show the big potential of stable beams and of binary reactions for the study of the properties of the neutron-rich nuclear many body systems.

  14. Shell structure and shape coexistence in {sup 195}Pb

    Energy Technology Data Exchange (ETDEWEB)

    Fant, B. [Helsinki Univ. (Finland). Dept. of Physics; Cederwall, B. [Royal Inst. of Tech., Physics Dept., Stockholm (Sweden); Cederkaell, J. [Royal Inst. of Tech., Physics Dept., Stockholm (Sweden); Norlin, L.O. [Royal Inst. of Tech., Physics Dept., Stockholm (Sweden); Wyss, R. [Royal Inst. of Tech., Physics Dept., Stockholm (Sweden); Fallon, P. [Lawrence Berkeley Lab., Berkeley, CA (United States); Beausang, C.W. [Oliver Lodge Lab., Univ. of Liverpool (United Kingdom); Butler, P.A. [Oliver Lodge Lab., Univ. of Liverpool (United Kingdom); Roberts, J.W. [Oliver Lodge Lab., Univ. of Liverpool (United Kingdom); Bruce, A.M. [Dept. of Mathematical Sciences, Univ. of Brighton (United Kingdom); Cullen, D.M. [Oak Ridge National Lab., TN (United States); Mullins, S.M. [Dept. of Physics and Astronomy, McMaster Univ., Hamilton, ON (Canada); Poynter, R.J. [Dept. of Physics, Univ. of York, Heslington (United Kingdom); Wadsworth, R. [Dept. of Physics, Univ. of York, Heslington (United Kingdom); Riley, M.A. [Florida State Univ., Tallahassee, FL (United States). Dept. of Physics; Korten, W. [Bonn Univ. (Germany). Inst. fuer Strahlen- und Kernphysik; Piiparinen, M.J. [Accelerator Lab., Univ. of Jyvaeskylae (Finland)

    1995-12-31

    {sup 195}Pb was investigated utilizing the reactions {sup 164}Dy({sup 36}S, 5n){sup 195}Pb and {sup 164}Dy({sup 34}S, 3n){sup 195}Pb at beam energies of 170 and 160 MeV respectively. Two new dipole bands which feed into the yrast 25/2{sup +} state, were found in {sup 195}Pb. The connection between the bands and the spherical states was established and thus spins and energies of the involved collective states were determined. The deformation is understood as mainly due to excitations of protons across the Z = 82 shell gap. The observed backbends are interpreted as alignment of i{sub 13/2} neutrons. (orig.).

  15. Eco-friendly synthesis of core-shell structured (TiO2/Li2CO3) nanomaterials for low cost dye-sensitized solar cells.

    Science.gov (United States)

    Karuppuchamy, S; Brundha, C

    2016-12-01

    Core-shell structured TiO 2 /Li 2 CO 3 electrode was successfully synthesized by eco-friendly solution growth technique. TiO 2 /Li 2 CO 3 electrodes were characterized using X-ray Diffractometer (XRD), Scanning electron microscopy (SEM) and photocurrent-voltage measurements. The synthesized core-shell electrode material was sensitized with tetrabutylammonium cis-di(thiocyanato)-N,N'-bis(4-carboxylato-4'-carboxylic acid-2,2'-bipyridine)ruthenate(II) (N-719). The performance of dye-sensitized solar cells (DSCs) based on N719 dye modified TiO 2 /Li 2 CO 3 electrodes was investigated. The effect of various shell thickness on the photovoltaic performance of the core-shell structured electrode is also investigated. We found that Li 2 CO 3 shells of all thicknesses perform as inert barriers which improve open-circuit voltage (V oc ) of the DSCs. The energy conversion efficiency was greatly dependent on the thickness of Li 2 CO 3 on TiO 2 film, and the highest efficiency of 3.7% was achieved at the optimum Li 2 CO 3 shell layer. Copyright © 2015 Elsevier Inc. All rights reserved.

  16. Nano-sized LiFePO4/C composite with core-shell structure as cathode material for lithium ion battery

    International Nuclear Information System (INIS)

    Liu, Yang; Zhang, Min; Li, Ying; Hu, Yemin; Zhu, Mingyuan; Jin, Hongming; Li, Wenxian

    2015-01-01

    Graphical abstract: Nano-sized LiFePO4/C composite with core-shell structure was fabricated via a well-designed approach as cathode material forlithium ion battery. The nano-sized LiFePO4/C composite with whole carbon shell coating layer showed an excellent electrical performance. - Abstract: Nano-sized composite with LiFePO 4 -core and carbon-shell was synthesized via a facile route followed by heat treatment at 650 °C. X-ray diffraction (XRD) shows that the core is well crystallized LiFePO 4 . The electron microscopy (SEM and TEM) observations show that the core-shell structured LiFePO 4 /C composite coating with whole carbon shell layer of ∼2.8 nm, possesses a specific surface area of 51 m 2 g −1 . As cathode material for lithium ion battery, the core-shell LiFePO 4 /C composite exhibits high initial capacity of 161 mAh g −1 at 0.1 C, excellent high-rate discharge capacity of 135 mAh g −1 at 5 C and perfect cycling retention of 99.6% at 100 th cycle. All these promising results should be contributed to the core-shell nanostructure which prevents collapse of the particle structure in the long-term charge and discharge cycles, as well as the large surface area of the nano-sized LiFePO 4 /C composite which enhances the electronic conductivity and shortens the distance of lithium ion diffusion

  17. Synthesis and properties MFe2O4 (M = Fe, Co) nanoparticles and core-shell structures

    Science.gov (United States)

    Yelenich, O. V.; Solopan, S. O.; Greneche, J. M.; Belous, A. G.

    2015-08-01

    Individual Fe3-xO4 and CoFe2O4 nanoparticles, as well as Fe3-xO4/CoFe2O4 core/shell structures were synthesized by the method of co-precipitation from diethylene glycol solutions. Core/shell structure were synthesized with CoFe2O4-shell thickness of 1.0, 2.5 and 3.5 nm. X-ray diffraction patterns of individual nanoparticles and core/shell are similar and indicate that all synthesized samples have a cubic spinel structure. Compares Mössbauer studies of CoFe2O4, Fe3-xO4 nanoparticles indicate superparamagnetic properties at 300 K. It was shown that individual magnetite nanoparticles are transformed into maghemite through oxidation during the synthesis procedure, wherein the smallest nanoparticles are completely oxidized while a magnetite core does occur in the case of the largest nanoparticles. The Mössbauer spectra of core/shell nanoparticles with increasing CoFe2O4-shell thickness show a gradual decrease in the relative intensity of the quadrupole doublet and significant decrease of the mean isomer shift value at both RT and 77 K indicating a decrease of the superparamagnetic relaxation phenomena. Specific loss power for the prepared ferrofluids was experimentally calculated and it was determined that under influence of ac-magnetic field magnetic fluid based on individual CoFe2O4 and Fe3-xO4 particles are characterized by very low heating temperature, when magnetic fluids based on core/shell nanoparticles demonstrate higher heating effect.

  18. Structure and stability of nickel/nickel oxide core-shell nanoparticles

    International Nuclear Information System (INIS)

    D'Addato, S; Grillo, V; Valeri, S; Frabboni, S; Altieri, S; Tondi, R

    2011-01-01

    The results of a combined x-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscopy (HR-TEM) study of Ni nanoparticles (NP), before and after oxidation, are presented. An experimental set-up was realized for the preparation and study of pre-formed NP films, concentrating the attention on Ni NP in the diameter range between 4 and 8 nm. The XPS data were taken in situ from NPs after different stages of oxidation, including controlled dosing of O 2 gas in the experimental system and exposure to the atmosphere. The Ni 2p structure is a combination of spectra from metallic Ni in the NP core and from the oxide shell. The signal from the NP core was observed even for samples after exposure to air. From the comparison of HR-TEM experimental images with theoretical simulations, it was found that the Ni NP core has a regular multitwinned icosahedral structure, composed of single-crystal tetrahedra with (111) faces. The NiO phase is clearly observed forming islands on the NP surface.

  19. Structure and stability of nickel/nickel oxide core-shell nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    D' Addato, S; Grillo, V; Valeri, S; Frabboni, S [CNR-Istituto Nanoscienze, Centro S3, Via G Campi 213/a, I-41125 Modena (Italy); Altieri, S; Tondi, R, E-mail: sergio.daddato@unimore.it [Dipartimento di Fisica, Universita di Modena e Reggio Emilia, via G Campi 213/a, I-41125 Modena (Italy)

    2011-05-04

    The results of a combined x-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscopy (HR-TEM) study of Ni nanoparticles (NP), before and after oxidation, are presented. An experimental set-up was realized for the preparation and study of pre-formed NP films, concentrating the attention on Ni NP in the diameter range between 4 and 8 nm. The XPS data were taken in situ from NPs after different stages of oxidation, including controlled dosing of O{sub 2} gas in the experimental system and exposure to the atmosphere. The Ni 2p structure is a combination of spectra from metallic Ni in the NP core and from the oxide shell. The signal from the NP core was observed even for samples after exposure to air. From the comparison of HR-TEM experimental images with theoretical simulations, it was found that the Ni NP core has a regular multitwinned icosahedral structure, composed of single-crystal tetrahedra with (111) faces. The NiO phase is clearly observed forming islands on the NP surface.

  20. Electronic structure of semiconductor interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Herman, F

    1983-02-01

    The study of semiconductor interfaces is one of the most active and exciting areas of current semiconductor research. Because interfaces play a vital role in modern semiconductor technology (integrated circuits, heterojunction lasers, solar cells, infrared detectors, etc.), there is a strong incentive to understand interface properties at a fundamental level and advance existing technology thereby. At the same time, technological advances such as molecular beam epitaxy have paved the way for the fabrication of semiconductor heterojunctions and superlattices of novel design which exhibit unusual electronic, optical, and magnetic properties and offer unique opportunities for fundamental scientific research. A general perspective on this subject is offered treating such topics as the atomic and electronic structure of semiconductor surfaces and interfaces; oxidation and oxide layers; semiconductor heterojunctions and superlattices; rectifying metal-semiconductor contacts; and interface reactions. Recent progress is emphasized and some future directions are indicated. In addition, the role that large-scale scientific computation has played in furthering our theoretical understanding of semiconductor surfaces and interfaces is discussed. Finally, the nature of theoretical models, and the role they play in describing the physical world is considered.

  1. Electronic structure of semiconductor interfaces

    International Nuclear Information System (INIS)

    Herman, F.

    1983-01-01

    The study of semiconductor interfaces is one of the most active and exciting areas of current semiconductor research. Because interfaces play a vital role in modern semiconductor technology (integrated circuits, heterojunction lasers, solar cells, infrared detectors, etc.), there is a strong incentive to understand interface properties at a fundamental level and advance existing technology thereby. At the same time, technological advances such as molecular beam epitaxy have paved the way for the fabrication of semiconductor heterojunctions and superlattices of novel design which exhibit unusual electronic, optical, and magnetic properties and offer unique opportunities for fundamental scientific research. A general perspective on this subject is offered treating such topics as the atomic and electronic structure of semiconductor surfaces and interfaces; oxidation and oxide layers; semiconductor heterojunctions and superlattices; rectifying metal-semiconductor contacts; and interface reactions. Recent progress is emphasized and some future directions are indicated. In addition, the role that large-scale scientific computation has played in furthering our theoretical understanding of semiconductor surfaces and interfaces is discussed. Finally, the nature of theoretical models, and the role they play in describing the physical world is considered. (Author) [pt

  2. Facile synthesis of core–shell structured PANI-Co_3O_4 nanocomposites with superior electrochemical performance in supercapacitors

    International Nuclear Information System (INIS)

    Hai, Zhenyin; Gao, Libo; Zhang, Qiang; Xu, Hongyan; Cui, Danfeng; Zhang, Zengxing; Tsoukalas, Dimitris; Tang, Jun; Yan, Shubin; Xue, Chenyang

    2016-01-01

    Graphical abstract: - Highlights: • PANI-Co_3O_4 is synthesized by carbon-assisted and in situ polymerization methods. • PANI coating improves the properties of Co_3O_4 affecting electrochemical performance. • The nanocomposites exhibit a high specific capacitance of 1184 F g"−"1 at 1.25 A g"−"1. - Abstract: Core–shell structured PANI-Co_3O_4 nanocomposites for supercapacitor applications were synthesized by combination of carbon-assisted method and in situ polymerization method. The crystalline structure, optical band gap, morphology, and hydrophilic property, as the major factors affecting the performances of supercapacitors, were investigated by X-ray diffraction (XRD), UV–vis spectrophotometry (UV–vis), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and water contact angle (WCA). The core–shell structured PANI-Co_3O_4 nanocomposites are characterized by amorphous PANI, small bandgaps, large surface area and favorable hydrophilicity, which indicates the superior electrochemical performances of the nanocomposites as electrode material for supercapacitors. Cyclic voltammetry (CV), galvanostatic charge/discharge and electrochemical impedance spectroscopy (EIS) measurements were conducted in 6 M KOH aqueous solution to evaluate the electrochemical performances. The results shows that core–shell structured PANI-Co_3O_4 nanocomposites exhibit a high specific capacitance of 1184 F g"−"1 at 1.25 A g"−"1, excellent cycling stability of a capacitance retention of 84.9% after 1000 galvanostatic charge/discharge cycles, good electrical conductivity and ion diffusion behavior.

  3. Electron shell contributions to gamma-ray spectra of positron annihilation in noble gases

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Feng; Selvam, Lalitha [Centre for Molecular Simulation, Swinburne University of Technology, PO Box 218, Hawthorn, Victoria 3122 (Australia); Gribakin, Gleb F [Department of Applied Mathematics and Theoretical Physics, Queen' s University Belfast BT7 1NN (United Kingdom); Surko, Clifford M, E-mail: fwang@swin.edu.a [Physics Department, University of California, San Diego, La Jolla, CA 92093-0319 (United States)

    2010-08-28

    Gamma-ray positron annihilation spectra of the noble gases are simulated using computational chemistry tools for the bound electron wavefunctions and plane-wave approximation for the low-energy positron. The present annihilation line shapes, i.e. the full width at half maximum, {Delta}{epsilon}, of the {gamma}-ray annihilation spectra for He and Ar (valence) agree well with available independent atomic calculations using a different algorithm. For other noble gases they achieve moderate agreement with the experimental measurements. It is found that the contributions of various atomic electron shells to the spectra depend significantly on their principal quantum number n and orbital angular momentum quantum number l. The present study further reveals that the outermost ns electrons of the noble gases exhibit spectral line shapes in close agreement with those measured, indicating (as expected) that the measurements are not due to a simple sum over the momentum densities for all atomic electrons. The robust nature of the present approach makes it possible for us to proceed to more complex molecular systems using the tools of modern computational chemistry.

  4. In-situ synthetize multi-walled carbon nanotubes@MnO2 nanoflake core-shell structured materials for supercapacitors

    Science.gov (United States)

    Zheng, Huajun; Wang, Jiaoxia; Jia, Yi; Ma, Chun'an

    2012-10-01

    A new type of core-shell structured material consisting of multi-walled carbon nanotubes (MWCNTs) and manganese dioxide (MnO2) nanoflake is synthesized using an in-situ co-precipitation method. By scanning electron microscopy and transition electron microscope, it is confirmed that the core-shell nanostructure is formed by the uniform incorporation of birnessite-type MnO2 nanoflake growth round the surface of the activated-MWCNTs. That core-shell structured material electrode presents excellent electrochemical capacitance properties with the specific capacitance reaching 380 F g-1 at the current density of 5 A g-1 in 0.5 M Na2SO4 electrolyte. In addition, the electrode also exhibits good performance (the power density: 11.28 kW kg-1 at 5 A g-1) and long-term cycling stability (retaining 82.7% of its initial capacitance after 3500 cycles at 5 A g-1). It mainly attributes to MWCNTs not only providing considerable specific surface area for high mass loading of MnO2 nanoflakes to ensure effective utilization of MnO2 nanoflake, but also offering an electron pathway to improve electrical conductivity of the electrode materials. It is clearly indicated that such core-shell structured materials including MWCNTs and MnO2 nanoflake may find important applications for supercapacitors.

  5. Harnessing the bistable composite shells to design a tunable phononic band gap structure

    Science.gov (United States)

    Li, Yi; Xu, Yanlong

    2018-02-01

    By proposing a system composed of an array of bistable composite shells immersed in air, we develop a new class of periodic structure to control the propagation of sound. Through numerical investigation, we find that the acoustic band gap of this system can be switched on and off by triggering the snap through deformation of the bistable composite shells. The shape of cross section and filling fraction of unit cell can be altered by different number of bistable composite shells, and they have strong impact on the position and width of the band gap. The proposed concept paves the way of using the bistable structures to design a new class of metamaterials that can be enable to manipulate sound.

  6. Shell and membrane theories in mechanics and biology from macro- to nanoscale structures

    CERN Document Server

    Mikhasev, Gennadi

    2015-01-01

    This book presents the latest results related to shells  characterize and design shells, plates, membranes and other thin-walled structures, a multidisciplinary approach from macro- to nanoscale is required which involves the classical disciplines of mechanical/civil/materials engineering (design, analysis, and properties) and physics/biology/medicine among others. The book contains contributions of a meeting of specialists (mechanical engineers, mathematicians, physicists and others) in such areas as classical and non-classical shell theories. New trends with respect to applications in mechanical, civil and aero-space engineering, as well as in new branches like medicine and biology are presented which demand improvements of the theoretical foundations of these theories and a deeper understanding of the material behavior used in such structures.

  7. Inner-Shell Excitations of 2p Electrons of Argon Investigated by Fast Electron Impact with High Resolution

    International Nuclear Information System (INIS)

    Ren Lin-Mao; Wang You-Yan; Li Dong-Dong; Yuan Zhen-Sheng; Zhu Lin-Fan

    2011-01-01

    Electron energy loss spectra of inner-shell excitations of 2p electrons of argon are measured at an incident electron energy of 2500 eV and scattering angles of 0° and 4°. The dipole-forbidden transitions of 2p −1 3/2 4p and 2p −1 3/2 5p are observed in the measured spectra and assigned based on the calculations of the Cowan code. The positions and line widths for the excitations of 2p −1 3/2 nl and 2p −1 1/2 nl (n ≤ 5) of argon are determined. The present results show that the line widths of the electric quadrupole transitions of 2p −1 3/2 4p[5/2 + 3/2] 2 and the electric monopole one of 2p −1 3/2 4p[1/2] 0 are less than those of the dipole-allowed transitions. (atomic and molecular physics)

  8. Computation of electron-impact K-shell ionization cross sections of atoms

    International Nuclear Information System (INIS)

    Uddin, M.A.; Haque, A.K.F.; Billah, M. Masum; Basak, A.K.; Karim, K.R.; Saha, B.C.

    2005-01-01

    The total cross sections of electron impact single K-shell ionization of atomic targets, with a wide range of atomic numbers from Z=6-50, are evaluated in the energy range up to about 10 MeV employing the recently proposed modified version of the improved binary-encounter dipole (RQIBED) model [Uddin et al., Phys. Rev. A 70, 032706 (2004)], which incorporates the ionic and relativistic effects. The experimental cross sections for all targets are reproduced satisfactorily even in the relativistic energies using fixed generic values of the two parameters in the RQIBED model. The relativistic effect is found to be significant in all targets except for C, being profound in Ag and Sn

  9. High resolution electron backscatter diffraction (EBSD) data from calcite biominerals in recent gastropod shells.

    Science.gov (United States)

    Pérez-Huerta, Alberto; Dauphin, Yannicke; Cuif, Jean Pierre; Cusack, Maggie

    2011-04-01

    Electron backscatter diffraction (EBSD) is a microscopy technique that reveals in situ crystallographic information. Currently, it is widely used for the characterization of geological materials and in studies of biomineralization. Here, we analyze high resolution EBSD data from biogenic calcite in two mollusk taxa, Concholepas and Haliotis, previously used in the understanding of complex biomineralization and paleoenvironmental studies. Results indicate that Concholepas has less ordered prisms than in Haliotis, and that in Concholepas the level of order is not homogenous in different areas of the shell. Overall, the usefulness of data integration obtained from diffraction intensity and crystallographic orientation maps, and corresponding pole figures, is discussed as well as its application to similar studies. © 2010 Elsevier Ltd. All rights reserved.

  10. Observation of hole accumulation in Ge/Si core/shell nanowires using off-axis electron holography.

    Science.gov (United States)

    Li, Luying; Smith, David J; Dailey, Eric; Madras, Prashanth; Drucker, Jeff; McCartney, Martha R

    2011-02-09

    Hole accumulation in Ge/Si core/shell nanowires (NWs) has been observed and quantified using off-axis electron holography and other electron microscopy techniques. The epitaxial [110]-oriented Ge/Si core/shell NWs were grown on Si (111) substrates by chemical vapor deposition through the vapor-liquid-solid growth mechanism. High-angle annular-dark-field scanning transmission electron microscopy images and off-axis electron holograms were obtained from specific NWs. The excess phase shifts measured by electron holography across the NWs indicated the presence of holes inside the Ge cores. Calculations based on a simplified coaxial cylindrical model gave hole densities of (0.4 ± 0.2) /nm(3) in the core regions.

  11. Structure of the first- and second-neighbor shells of simulated water: Quantitative relation to translational and orientational order

    Science.gov (United States)

    Yan, Zhenyu; Buldyrev, Sergey V.; Kumar, Pradeep; Giovambattista, Nicolas; Debenedetti, Pablo G.; Stanley, H. Eugene

    2007-11-01

    We perform molecular dynamics simulations of water using the five-site transferable interaction potential (TIP5P) model to quantify structural order in both the first shell (defined by four nearest neighbors) and second shell (defined by twelve next-nearest neighbors) of a central water molecule. We find that the anomalous decrease of orientational order upon compression occurs in both shells, but the anomalous decrease of translational order upon compression occurs mainly in the second shell. The decreases of translational order and orientational order upon compression (called the “structural anomaly”) are thus correlated only in the second shell. Our findings quantitatively confirm the qualitative idea that the thermodynamic, structural, and hence dynamic anomalies of water are related to changes upon compression in the second shell.

  12. Polypyrrole shell@3D-Ni metal core structured electrodes for high-performance supercapacitors.

    Science.gov (United States)

    Chen, Gao-Feng; Su, Yu-Zhi; Kuang, Pan-Yong; Liu, Zhao-Qing; Chen, Dao-Yi; Wu, Xu; Li, Nan; Qiao, Shi-Zhang

    2015-03-16

    Three-dimensional (3D) nanometal films serving as current collectors have attracted much interest recently owing to their promising application in high-performance supercapacitors. In the process of the electrochemical reaction, the 3D structure can provide a short diffusion path for fast ion transport, and the highly conductive nanometal may serve as a backbone for facile electron transfer. In this work, a novel polypyrrole (PPy) shell@3D-Ni-core composite is developed to enhance the electrochemical performance of conventional PPy. With the introduction of a Ni metal core, the as-prepared material exhibits a high specific capacitance (726 F g(-1) at a charge/discharge rate of 1 A g(-1)), good rate capability (a decay of 33% in Csp with charge/discharge rates increasing from 1 to 20 A g(-1)), and high cycle stability (only a small decrease of 4.2% in Csp after 1000 cycles at a scan rate of 100 mV s(-1)). Furthermore, an aqueous symmetric supercapacitor device is fabricated by using the as-prepared composite as electrodes; the device demonstrates a high energy density (≈21.2 Wh kg(-1)) and superior long-term cycle ability (only 4.4% and 18.6% loss in Csp after 2000 and 5000 cycles, respectively). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. The shell structure effects in neutron cross section calculation by a ...

    African Journals Online (AJOL)

    The role of the shell structure properties of the nucleus in the calculation of neutron-induced reaction cross-section data based on nuclear reaction theory has been investigated. In this investigation, measured, evaluated and calculated (n.p) reaction cross-section data on la spherical nucleus (i.e. 112Sn) and a deformed ...

  14. Study of band structure in 78,80Sr using Triaxial Projected Shell Model

    International Nuclear Information System (INIS)

    Behera, N.; Naik, Z.; Bhat, G.H.; Sheikh, J.A.; Palit, R.; Sun, Y.

    2017-01-01

    The purpose of present work is to carry out a systematic study of the yrast-band and gamma-band structure for the even-even 78-80 Sr nuclei using Triaxial Projected Shell Model (TPSM) approach. These nuclei were chosen because 78 Sr has well developed side band(unassigned configuration) and 80 Sr has well developed band observed experimentally

  15. Nuclear structure of s-d shell nuclei: what is new?

    International Nuclear Information System (INIS)

    Shanmugam, G.

    1995-01-01

    In this paper the shape evolution of the even-even s-d shell nuclei with temperature and spin is studied using Landau theory of phase transitions. The most important thermal fluctuations are incorporated in this study. The ground state pairing is also included in the calculations. Both the summation and Strutinsky methods are used for extracting the Landau constants. Both yield qualitatively similar results. To conclude, Landau theory of phase transitions can be effectively and economically used to study the structure of excited s-d shell nuclei. 10 refs., 2 tabs., 8 figs

  16. Formation of an Anti-Core–Shell Structure in Layered Oxide Cathodes for Li-Ion Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hanlei [Materials; amp, Department; NorthEast; Omenya, Fredrick [NorthEast; Whittingham, M. Stanley [NorthEast; Wang, Chongmin [Environmental; Zhou, Guangwen [Materials; amp, Department; NorthEast

    2017-10-20

    The layered → rock-salt phase transformation in the layered dioxide cathodes for Li-ion batteries is believed to result in a “core-shell” structure of the primary particles, in which the core region maintains as the layered phase while the surface region undergoes the phase transformation to the rock-salt phase. Using transmission electron microscopy, here we demonstrate the formation of an “anti-core-shell” structure in cycled primary particles with a formula of LiNi0.80Co0.15Al0.05O2, in which the surface and subsurface regions remain as the layered structure while the rock-salt phase forms as domains in the bulk with a thin layer of the spinel phase between the rock-salt core and the skin of the layered phase. Formation of this anti-core-shell structure is attributed to the oxygen loss at the surface that drives the migration of oxygen from the bulk to the surface, thereby resulting in localized areas of significantly reduced oxygen levels in the bulk of the particle, which subsequently undergoes the phase transformation to the rock-salt domains. The formation of the anti-core-shell rock-salt domains is responsible for the reduced capacity, discharge voltage and ionic conductivity in cycled cathode.

  17. Optimal design of hollow core–shell structural active materials for lithium ion batteries

    Directory of Open Access Journals (Sweden)

    Wenjuan Jiang

    2015-01-01

    Full Text Available To mitigate mechanical and chemical degradation of active materials, hollow core–shell structures have been applied in lithium ion batteries. Without embedding of lithium ions, the rigid coating shell can constrain the inward volume deformation. In this paper, optimal conditions for the full use of inner hollow space are identified in terms of the critical ratio of shell thickness and inner size and the state of charge. It is shown that the critical ratios are 0.10 and 0.15 for Si particle and tube (0.12 and 0.18 for Sn particle and tube, and above which there is lack of space for further lithiation.

  18. What explains the structure of Enceladus's ice shell and can it be in equilibrium?

    Science.gov (United States)

    Hemingway, D.; Mittal, T.

    2017-12-01

    Over the course of the Cassini mission, a series of geodetic measurements [1-3] have revealed that Enceladus's ongoing south polar eruptions are likely sourced from a global subsurface liquid water ocean [2-6]. The extent of the ocean and the structure of the overlying ice shell are of particular importance as they speak to the nature of the eruptions and the thermal state and evolution of Enceladus. How quickly is Enceladus cooling? Is the ocean a recent, perhaps transient phenomenon, or has it been present for billions of years? Based on shape, gravity, and libration observations, the floating ice shell is inferred to be thickest at the equator, where it is perhaps 35-45 km thick at the sub- and anti-Saturnian points, and thinnest at the poles, especially beneath the broad topographic depression associated with the South Polar Terrain (SPT), where the shell is likely less—perhaps much less—than 10 km thick [6,7]. Although tidal heating is assumed to be the mechanism primarily responsible for the observed shell structure, and whereas several theoretical studies have been carried out [e.g., 8], a clear match between theory and observations has yet to be demonstrated. Likewise, the question of whether or not the current configuration can be in equilibrium, remains open. Here we model the effects of tidal heating on Enceladus's ice shell, showing that the expected equilibrium ice shell structure is largely consistent with the structure inferred from shape, gravity, and libration observations. We consider the nature of the north-south polar asymmetry in shell structure and geologic activity, and we address the question of whether or not the current structure can be maintained in spite of ongoing relaxation. In light of our results, we discuss implications for the heat budget and thermal evolution of Enceladus. [1] P. Thomas et al., Icarus 190 (2), 573-584, Oct. 2007. [2] L. Iess et al., Science 344 (6179), 78-80, 2014. [3] P. C. Thomas et al., Icarus 264, 37

  19. Improved atomic data for electron-transport predictions by the codes TIGER and TIGERP. I. Inner-shell ionization by electron collision

    International Nuclear Information System (INIS)

    Peek, J.M.; Halbleib, J.A.

    1983-01-01

    The inner-shell ionization data for electron-target collisions now in use in the TIGER and TIGERP electron-transport codes are extracted and compared with other data for these processes. The TIGER cross sections for K-shell ionization by electron collisions are found to be seriously in error for large-Z targets and incident electron energies greater than 1 MeV. A series of TIGER and TIGERP runs were carried out with and without improved K-shell electron ionization cross section data replacing that now in use. The relative importance of electron-impact and photon ionization of the various subshells was also extracted from these runs. In general, photon ionization dominated in the examples studied so the sensitivity of many predicted properties to errors in the electron-impact subshell ionization data was not large. However, some differences were found and, as all possible applications were not covered in this study, it is recommended that these electron-impact data now in TIGER and TIGERP be replaced. Cross section data for the processes under study are reviewed and those that are most suitable for this application are identified. 19 references, 9 figures, 2 tables

  20. Plasma-assisted synthesis and study of structural and magnetic properties of Fe/C core shell

    Science.gov (United States)

    Shinde, K. P.; Ranot, M.; Choi, C. J.; Kim, H. S.; Chung, K. C.

    2017-07-01

    Pure and carbon-encapsulated iron nanoparticles with an average diameter of 25 nm were synthesized by using the DC plasma arc discharge method. Fe core nanoparticles were encapsulated with carbon layer, which is acting as protection layer against both oxidation and chemical reaction. The morphology and the Fe/C core/shell structure of the nanoparticles were studied by using field emission scanning electron microscopy and transmission electron microscopy. The x-ray diffraction study showed that the α-Fe phase exists with γ-Fe as an impurity. The studied samples have been interrelated with the variation of saturation magnetization, remanent magnetization and coercive field with the amount of carbon coating. The pure α-Fe sample shows saturation magnetization = 172 emu/g, and coercive field = 150 Oe, on the other hand few layer carbon coated α-Fe sample shows saturation magnetization =169 emu/g with higher coercive field 398 Oe.

  1. Plasma-assisted synthesis and study of structural and magnetic properties of Fe/C core shell

    Directory of Open Access Journals (Sweden)

    K. P. Shinde

    2017-07-01

    Full Text Available Pure and carbon-encapsulated iron nanoparticles with an average diameter of 25 nm were synthesized by using the DC plasma arc discharge method. Fe core nanoparticles were encapsulated with carbon layer, which is acting as protection layer against both oxidation and chemical reaction. The morphology and the Fe/C core/shell structure of the nanoparticles were studied by using field emission scanning electron microscopy and transmission electron microscopy. The x-ray diffraction study showed that the α-Fe phase exists with γ-Fe as an impurity. The studied samples have been interrelated with the variation of saturation magnetization, remanent magnetization and coercive field with the amount of carbon coating. The pure α-Fe sample shows saturation magnetization = 172 emu/g, and coercive field = 150 Oe, on the other hand few layer carbon coated α-Fe sample shows saturation magnetization =169 emu/g with higher coercive field 398 Oe.

  2. Characterization of magnetic core-shell nanoparticles by fluxgate magnetorelaxometry, ac susceptibility, transmission electron microscopy and photon correlation spectroscopy-A comparative study

    International Nuclear Information System (INIS)

    Ludwig, Frank; Heim, Erik; Schilling, Meinhard

    2009-01-01

    We have compared the structure parameters of magnetic core-shell nanoparticles determined from fluxgate magnetorelaxometry measurements applying the moment superposition model with the results from other methods. For the characterization of the magnetic cores, the nanoparticles are immobilized by freeze-drying. The core size distribution estimated for superparamagnetic Fe 3 O 4 magnetic nanoparticles (MNPs) with polyacrylic acid shell agrees well with that from transmission electron microscopy measurements. The distribution of hydrodynamic diameters of nanoparticle suspensions estimated from magnetorelaxometry measurements is in good agreement with that obtained from ac susceptibility and photon correlation spectroscopy measurements. Advantages of magnetorelaxometry compared to the other two integral techniques are that it is fast and the signal is less dominated by larger particles.

  3. Investigations of the valence-shell excitations of molecular ethane by high-energy electron scattering

    Science.gov (United States)

    Xu, Wei-Qing; Xu, Long-Quan; Qi, De-Guang; Chen, Tao; Liu, Ya-Wei; Zhu, Lin-Fan

    2018-04-01

    The differential cross sections and generalized oscillator strengths for the low-lying excitations of the valence-shell 1eg orbital electron in ethane have been measured for the first time at a high incident electron energy of 1500 eV and a scattering angular range of 1.5°-10°. A weak feature, termed X here, with a band center of about 7.5 eV has been observed, which was also announced by the previous experimental and theoretical studies. The dynamic behaviors of the generalized oscillator strengths for the 3s (8.7 eV), 3s+3p (9.31 eV, 9.41 eV), and X (˜7.5 eV) transitions on the momentum transfer squared have been obtained. The integral cross sections of these transitions from their thresholds to 5000 eV have been obtained with the aid of the BE-scaling (B is the binding energy and E is the excitation energy) method. The optical oscillator strengths of the above transitions determined by extrapolating their generalized oscillator strengths to the limit of the squared momentum transfer K2 → 0 are in good agreement with the ones from the photoabsorption spectrum [J. W. Au et al., Chem. Phys. 173, 209 (1993)], which indicates that the present differential cross sections, generalized oscillator strengths, and integral cross sections can serve as benchmark data.

  4. Form-finding of shell structures generated from physical models

    NARCIS (Netherlands)

    Li, Q.; Su, Y; Wu, Y; Borgart, A.; Rots, J.G.

    2017-01-01

    Vector form intrinsic finite element is a recently developed and promising numerical method for the analysis of complicated structural behavior. Taking the cable-link element as example, the framework of the vector form intrinsic finite element is explained first. Based on this, a constant strain

  5. Core shell structured nanoparticles of Eu3+ doped SnO2 with SiO2 shell: luminescence studies

    International Nuclear Information System (INIS)

    Ningthoujam, R.S.; Sudarsan, V.; Kulshreshtha, S.K.

    2005-01-01

    Re dispersible SnO 2 nanoparticles with and without Eu 3+ doping nanoparticles were prepared at 185 deg C by the urea hydrolysis of Sn 4+ in ethylene glycol medium. X-ray diffraction and 119 Sn MAS NMR studies of these particles revealed that these nanoparticles are crystalline with Cassiterite structure having an average crystallite size of 7 nm. Undoped SnO 2 gave a emission peak centered around 470 nm characteristic of the traps present in the nanoparticles. For Eu 3+ doped samples, emission around 590 and 615 nm was observed on both direct excitation as well as indirect excitation through traps, indicating that there is an energy transfer between the traps present in the nanoparticles and Eu 3+ ions. The asymmetric ratio of luminescence (relative intensity ratio of 590 to 615 nm transitions) has been found to be 1.2. For SnO 2 :Eu(5%)-SiO 2 nanoparticles, the asymmetric ratio of luminescence change significantly indicating the formation of nanoparticles with SnO 2 :Eu(5%) core covered with SiO 2 shell. (author)

  6. Structure of liposome encapsulating proteins characterized by X-ray scattering and shell-modeling

    International Nuclear Information System (INIS)

    Hirai, Mitsuhiro; Kimura, Ryota; Takeuchi, Kazuki; Hagiwara, Yoshihiko; Kawai-Hirai, Rika; Ohta, Noboru; Igarashi, Noriyuki; Shimuzu, Nobutaka

    2013-01-01

    Wide-angle X-ray scattering data using a third-generation synchrotron radiation source are presented. Lipid liposomes are promising drug delivery systems because they have superior curative effects owing to their high adaptability to a living body. Lipid liposomes encapsulating proteins were constructed and the structures examined using synchrotron radiation small- and wide-angle X-ray scattering (SR-SWAXS). The liposomes were prepared by a sequential combination of natural swelling, ultrasonic dispersion, freeze-throw, extrusion and spin-filtration. The liposomes were composed of acidic glycosphingolipid (ganglioside), cholesterol and phospholipids. By using shell-modeling methods, the asymmetric bilayer structure of the liposome and the encapsulation efficiency of proteins were determined. As well as other analytical techniques, SR-SWAXS and shell-modeling methods are shown to be a powerful tool for characterizing in situ structures of lipid liposomes as an important candidate of drug delivery systems

  7. Physical mechanism causing rapid changes in ultrarelativistic electron pitch angle distributions right after a shock arrival: Evaluation of an electron dropout event: Drift Shell Splitting on the Dayside

    International Nuclear Information System (INIS)

    Zhang, X.-J.; University of California, Los Angeles, CA; Li, W.; Boston University, MA; Thorne, R. M.

    2016-01-01

    Three mechanisms have been proposed to explain relativistic electron flux depletions (dropouts) in the Earth's outer radiation belt during storm times: adiabatic expansion of electron drift shells due to a decrease in magnetic field strength, magnetopause shadowing and subsequent outward radial diffusion, and precipitation into the atmosphere (driven by EMIC wave scattering). Which mechanism predominates in causing electron dropouts commonly observed in the outer radiation belt is still debatable. In the present study, we evaluate the physical mechanism that may be primarily responsible for causing the sudden change in relativistic electron pitch angle distributions during a dropout event observed by Van Allen Probes during the main phase of the 27 February 2014 storm. During this event, the phase space density of ultrarelativistic (>1MeV) electrons was depleted by more than 1 order of magnitude over the entire radial extent of the outer radiation belt (3 < L* < 5) in less than 6 h after the passage of an interplanetary shock. We model the electron pitch angle distribution under a compressed magnetic field topology based on actual solar wind conditions. Although these ultrarelativistic electrons exhibit highly anisotropic (peaked in 90°), energy-dependent pitch angle distributions, which appear to be associated with the typical EMIC wave scattering, comparison of the modeled electron distribution to electron measurements indicates that drift shell splitting is responsible for this rapid change in electron pitch angle distributions. This further indicates that magnetopause loss is the predominant cause of the electron dropout right after the shock arrival.

  8. Dynamical load factor of impact loaded shell structures

    International Nuclear Information System (INIS)

    Hammel, J.

    1977-01-01

    Dynamical loaded structures can be analysed by spectral representations, which usually lead to an enormous computational effort. If it is possible to find a fitting dynamical load factor, the dynamical problem can be reduced to a statical one. The computation of this statical problem is much simpler. The disadvantage is that the dynamical load factor usually leads to a very rough approximation. In this paper it will be shown, that by combination of these two methods, the approximation of the dynamical load factor can be improved and the consumption of computation time can be enormously reduced. (Auth.)

  9. Fabrication and Raman scattering of a core–shell structure based on Mn doped ZnO and barium titanate

    International Nuclear Information System (INIS)

    Sima, M.; Baibarac, M.; Vasile, E.; Sima, Ma.; Mihut, L.

    2015-01-01

    Graphical abstract: - Highlights: • ZnO/Zn_1_−_xMn_xO/BaTiO_3 nanorod array on FTO substrate. • Oxygen vacancies in the ZnO/Zn_1_−_xMn_xO nanostructure. • The interface between the ZnO/Zn_1_−_xMn_xO core and the BaTiO_3 shell without unwanted phases. - Abstract: A combination of chemical and thermal annealing techniques was used to prepare an array of ZnO/Zn_1_−_xMn_xO/BaTiO_3 nanorods. ZnO nanorod arrays were obtained by hydrothermal–electrochemical processes. The precursors for Zn_1_−_xMn_xO and BaTiO_3, prepared by sol–gel technique were deposited by spin coating on the surface of ZnO nanorods. Each deposition stage was accompanied by thermal treatment stages. Scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and photoluminescence spectroscopy reveal the presence of a film of Zn_1_−_xMn_xO with wurtzite structure on the surface of ZnO nanorods. Transmission electron microscopy images demonstrate that a layer of BaTiO_3 is deposited on the surface of each ZnO/Zn_1_−_xMn_xO core shell nanorod. BaTiO_3 film onto the ZnO/Zn_1_−_xMn_xO core shell nanorods is also evidenced in Raman scattering by broadening of the Raman band situated in the spectral range 500–750 cm"−"1.

  10. Fabrication and Raman scattering of a core–shell structure based on Mn doped ZnO and barium titanate

    Energy Technology Data Exchange (ETDEWEB)

    Sima, M., E-mail: msima@infim.ro [National Institute of Materials Physics, 105 bis Atomistilor Street, PO Box MG 7, 077125 Magurele (Romania); Baibarac, M. [National Institute of Materials Physics, 105 bis Atomistilor Street, PO Box MG 7, 077125 Magurele (Romania); Vasile, E. [University “Politehnica” of Bucharest, Faculty of Applied Chemistry and Material Science, Department of Oxide Materials and Nanomaterials, No. 1-7 Gh. Polizu Street, 011061 Bucharest (Romania); Sima, Ma.; Mihut, L. [National Institute of Materials Physics, 105 bis Atomistilor Street, PO Box MG 7, 077125 Magurele (Romania)

    2015-11-15

    Graphical abstract: - Highlights: • ZnO/Zn{sub 1−x}Mn{sub x}O/BaTiO{sub 3} nanorod array on FTO substrate. • Oxygen vacancies in the ZnO/Zn{sub 1−x}Mn{sub x}O nanostructure. • The interface between the ZnO/Zn{sub 1−x}Mn{sub x}O core and the BaTiO{sub 3} shell without unwanted phases. - Abstract: A combination of chemical and thermal annealing techniques was used to prepare an array of ZnO/Zn{sub 1−x}Mn{sub x}O/BaTiO{sub 3} nanorods. ZnO nanorod arrays were obtained by hydrothermal–electrochemical processes. The precursors for Zn{sub 1−x}Mn{sub x}O and BaTiO{sub 3}, prepared by sol–gel technique were deposited by spin coating on the surface of ZnO nanorods. Each deposition stage was accompanied by thermal treatment stages. Scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and photoluminescence spectroscopy reveal the presence of a film of Zn{sub 1−x}Mn{sub x}O with wurtzite structure on the surface of ZnO nanorods. Transmission electron microscopy images demonstrate that a layer of BaTiO{sub 3} is deposited on the surface of each ZnO/Zn{sub 1−x}Mn{sub x}O core shell nanorod. BaTiO{sub 3} film onto the ZnO/Zn{sub 1−x}Mn{sub x}O core shell nanorods is also evidenced in Raman scattering by broadening of the Raman band situated in the spectral range 500–750 cm{sup −1}.

  11. Characterization of core-shell GaAs/AlGaAs nanowire heterostructures using advanced electron microscopy

    International Nuclear Information System (INIS)

    Tambe, M J; Gradecak, S; Allard, L F

    2010-01-01

    To explore the unique properties of the nanoscale, advanced fabrication and characterization techniques are required. Specifically analyses in two orthogonal directions, plan-view and cross-section, were used to prove the core-shell morphology of GaAs/AlGaAs nanowires and determine their cross-section to be hexagonal. High-resolution transmission electron microscopy and high angle annular dark field scanning transmission electron microscopy confirmed the core-shell interface to be defect-free, coherent, and sharp ( 0.9 Ga 0.1 As uniformly along the length of the nanowire. These results demonstrate the power of electron microscopy to aid the development of semiconductor nanotechnology.

  12. Characterization of core/shell structures based on CdTe and GaAs nanocrystalline layers deposited on SnO2 microwires

    Science.gov (United States)

    Ghimpu, L.; Ursaki, V. V.; Pantazi, A.; Mesterca, R.; Brâncoveanu, O.; Shree, Sindu; Adelung, R.; Tiginyanu, I. M.; Enachescu, M.

    2018-04-01

    We report the fabrication and characterization of SnO2/CdTe and SnO2/GaAs core/shell microstructures. CdTe or GaAs shell layers were deposited by radio-frequency (RF) magnetron sputtering on core SnO2 microwires synthesized by a flame-based thermal oxidation method. The produced structures were characterized by scanning electron microscopy (SEM), high-resolution scanning transmission electron microscope (HR-STEM), X-ray diffraction (XRD), Raman scattering and FTIR spectroscopy. It was found that the SnO2 core is of the rutile type, while the shells are composed of CdTe or GaAs nanocrystallites of zincblende structure with the dimensions of crystallites in the range of 10-20 nm. The Raman scattering investigations demonstrated that the quality of the porous nanostructured shell is improved by annealing at temperatures of 420-450 °C. The prospects of implementing these microstructures in intrinsic type fiber optic sensors are discussed.

  13. Electronic structure studies of fullerites and fullerides

    International Nuclear Information System (INIS)

    Merkel, M.; Sohmen, E.; Masaki, A.; Romberg, H.; Alexander, M.; Knupfer, M.; Golden, M.S.; Adelmann, P.; Renker, B.; Fink, J.

    1993-01-01

    The electronic structure of fullerites and fullerides has been investigated by high-resolution photoemission and by high-energy electron energy-loss spectroscopy in transmission. Information on the occupied Π and σ bands, on the unoccupied Π * and σ * bands, and on the joint density of states has been obtained. In particular, we report on the changes of the electronic structure of fullerides as a function of dopant concentration. (orig.)

  14. Solvated electron structure in glassy matrices

    International Nuclear Information System (INIS)

    Kevan, L.

    1981-01-01

    Current knowledge of the detailed geometrical structure of solvated electrons in aqueous and organic media is summarized. The geometry of solvated electrons in glassy methanol, ethanol, and 2-methyltetrahydrofuran is discussed. Advanced electron magnetic resonance methods and development of new methods of analysis of electron spin echo modulation patterns, second moment line shapes, and forbidden photon spin-flip transitions for paramagnetic species in these disordered systems are discussed. 66 references are cited

  15. Shell structure of the A = 6 ground states from three-body dynamics

    International Nuclear Information System (INIS)

    Lehman, D.R.; Parke, W.C.

    1983-01-01

    Three-body (αNN) models of the 6 He and 6 Li ground states are used to investigate their shell structure. Three models for each nucleus are considered: simple, full (nn), and full (np) for 6 He, and simple, full (0%), and full (4%) for 6 Li. The full models in both cases are obtained by including the S/sub 1/2/, P/sub 1/2/, and P/sub 3/2/ partial waves of the αN interaction, whereas the simple model truncates to only the strongly resonant P/sub 3/2/ wave. The 6 He full models distinguish between use of the nn or np parameters for the 1 S 0 NN interaction, while the 6 Li full models have either a pure 3 S 1 NN interaction (0%) or a 3 S 1 - 3 D 1 interaction that leads to a 4% d-wave component in the deuteron (4%). These models are used to calculate the probabilities of the orbital components of the wave functions, the configuration-space single-particle orbital densities, and the configuration-space two-particle wave function amplitudes in j-j coupling with the nucleon coordinates referred to the alpha particle as the ''core'' or ''center of force.'' The results are then compared with those from phenomenological and realistic-interaction shell models. Major findings of the comparison are the following: None of the shell models considered have a distribution of orbital probabilities across shells like that predicted by three-body models; the orbital rms radii from three-body models indicate an ordering of the orbits within shells, i.e., p/sub 1/2/ outside p/sub 3/2/, unlike oscillator shell models with a single oscillator parameter where the p-shell orbitals have the same shape; and, as expected, three-body orbital densities decay at large radial distances as exponentials rather than the too compact Gaussian falling off of oscillator shell models

  16. Design and Manufacture of Conical Shell Structures Using Prepreg Laminates

    Science.gov (United States)

    Khakimova, Regina; Burau, Florian; Degenhardt, Richard; Siebert, Mark; Castro, Saullo G. P.

    2016-06-01

    The design and manufacture of unstiffened composite conical structures is very challenging, as the variation of the fiber orientations, lay-up and the geometry of the ply pieces have a significant influence on the thickness imperfections and ply angle deviations imprinted to the final part. This paper deals with the manufacture of laminated composite cones through the prepeg/autoclave process. The cones are designed to undergo repetitive buckling tests without accumulating permanent damage. The aim is to define a process that allows the control of fiber angle deviations and the removal of thickness imperfections generated from gaps and overlaps between ply pieces. Ultrasonic scan measurements are used to proof the effectiveness of the proposed method.

  17. Electronic structure and tautomerism of thioamides

    Energy Technology Data Exchange (ETDEWEB)

    Novak, Igor, E-mail: inovak@csu.edu.au [Charles Sturt University, POB 883, Orange, NSW 2800 (Australia); Klasinc, Leo, E-mail: klasinc@irb.hr [Physical Chemistry Department, Ruđer Bošković Institute, HR-10002 Zagreb (Croatia); McGlynn, Sean P., E-mail: sean.mcglynn@chemgate.chem.lsu.edu [Louisiana State University, Baton Rouge, LA 70803 (United States)

    2016-05-15

    Highlights: • Electronic structure of thioamide group and its relation to Lewis basicity. • Tautomerism of the (thio)amide groups. • Substituent effects on the electronic structure of (thio)amide group. - Abstract: The electronic structures of several thioamides have been studied by UV photoelectron spectroscopy (UPS). The relative stabilities of keto–enol tautomers have been determined using high-level ab initio calculations and the results were used in the analysis of UPS spectra. The main features of electronic structure and tautomerism of thioamide derivatives are discussed. The predominant tautomers in the gas phase are of keto–(thio)keto form. The addition of cyclohexanone moiety to the thioamide group enhances the Lewis base character of the sulfur atom. The addition of phenyl group to the (thio)amide group significantly affects its electronic structure.

  18. Catalyst-free fabrication of novel ZnO/CuO core-Shell nanowires heterojunction: Controlled growth, structural and optoelectronic properties

    Science.gov (United States)

    Khan, Muhammad Arif; Wahab, Yussof; Muhammad, Rosnita; Tahir, Muhammad; Sakrani, Samsudi

    2018-03-01

    Development of controlled growth and vertically aligned ZnO/CuO core-shell heterojunction nanowires (NWs) with large area by a catalyst free vapor deposition and oxidation approach has been investigated. Structural characterization reveals successful fabrication of a core ZnO nanowire having single crystalline hexagonal wurtzite structure along [002] direction and CuO nanostructure shell with thickness (8-10 nm) having polycrystalline monoclinic structure. The optical property analysis suggests that the reflectance spectrum of ZnO/CuO heterostructure nanowires is decreased by 18% in the visible range, which correspondingly shows high absorption in this region as compared to pristine ZnO nanowires. The current-voltage (I-V) characteristics of core-shell heterojunction nanowires measured by conductive atomic force microscopy (C-AFM) shows excellent rectifying behavior, which indicates the characteristics of a good p-n junction. The high-resolution transmission electron microscopy (HRTEM) has confirmed the sharp junction interface between the core-shell heterojunction nanowire arrays. The valence band offset and conduction band offset at ZnO/CuO heterointerfaces are measured to be 2.4 ± 0.05 and 0.23 ± 0.005 eV respectively, using X-ray photoelectron spectroscopy (XPS) and a type-II band alignment structure is found. The results of this study contribute to the development of new advanced device heterostructures for solar energy conversion and optoelectronics applications.

  19. Electron cryo-tomographic structure of cystovirus phi 12.

    Science.gov (United States)

    Hu, Guo-Bin; Wei, Hui; Rice, William J; Stokes, David L; Gottlieb, Paul

    2008-03-01

    Bacteriophage phi 12 is a member of the Cystoviridae virus family and contains a genome consisting of three segments of double-stranded RNA (dsRNA). This virus family contains eight identified members, of which four have been classified in regard to their complete genomic sequence and encoded viral proteins. A phospholipid envelope that contains the integral proteins P6, P9, P10, and P13 surrounds the viral particles. In species phi 6, host infection requires binding of a multimeric P3 complex to type IV pili. In species varphi8, phi 12, and phi 13, the attachment apparatus is a heteromeric protein assembly that utilizes the rough lipopolysaccharide (rlps) as a receptor. In phi 8 the protein components are designated P3a and P3b while in species phi 12 proteins P3a and P3c have been identified in the complex. The phospholipid envelope of the cystoviruses surrounds a nucleocapsid (NC) composed of two shells. The outer shell is composed of protein P8 with a T=13 icosahedral lattice while the primary component of the inner shell is a dodecahedral frame composed of dimeric protein P1. For the current study, the 3D architecture of the intact phi 12 virus was obtained by electron cryo-tomography. The nucleocapsid appears to be centered within the membrane envelope and possibly attached to it by bridging structures. Two types of densities were observed protruding from the membrane envelope. The densities of the first type were elongated, running parallel, and closely associated to the envelope outer surface. In contrast, the second density was positioned about 12 nm above the envelope connected to it by a flexible low-density stem. This second structure formed a torroidal structure termed "the donut" and appears to inhibit BHT-induced viral envelope fusion.

  20. Electron cryo-tomographic structure of cystovirus φ12

    International Nuclear Information System (INIS)

    Hu Guobin; Wei Hui; Rice, William J.; Stokes, David L.; Gottlieb, Paul

    2008-01-01

    Bacteriophage φ12 is a member of the Cystoviridae virus family and contains a genome consisting of three segments of double-stranded RNA (dsRNA). This virus family contains eight identified members, of which four have been classified in regard to their complete genomic sequence and encoded viral proteins. A phospholipid envelope that contains the integral proteins P6, P9, P10, and P13 surrounds the viral particles. In species φ6, host infection requires binding of a multimeric P3 complex to type IV pili. In species φ8, φ12, and φ13, the attachment apparatus is a heteromeric protein assembly that utilizes the rough lipopolysaccharide (rlps) as a receptor. In φ8 the protein components are designated P3a and P3b while in species φ12 proteins P3a and P3c have been identified in the complex. The phospholipid envelope of the cystoviruses surrounds a nucleocapsid (NC) composed of two shells. The outer shell is composed of protein P8 with a T = 13 icosahedral lattice while the primary component of the inner shell is a dodecahedral frame composed of dimeric protein P1. For the current study, the 3D architecture of the intact φ12 virus was obtained by electron cryo-tomography. The nucleocapsid appears to be centered within the membrane envelope and possibly attached to it by bridging structures. Two types of densities were observed protruding from the membrane envelope. The densities of the first type were elongated, running parallel, and closely associated to the envelope outer surface. In contrast, the second density was positioned about 12 nm above the envelope connected to it by a flexible low-density stem. This second structure formed a torroidal structure termed 'the donut' and appears to inhibit BHT-induced viral envelope fusion

  1. Ionic core–shell dendrimers with a polycationic core: structural aspects and host–guest binding properties

    NARCIS (Netherlands)

    van de Coevering, R.; Bruijnincx, P.C.A.; Lutz, M.; Spek, A.L.; van Koten, G.; Klein Gebbink, R.J.M.

    2007-01-01

    The structural aspects and host–guest binding properties of ionic core–shell dendrimers [1]Br8 and [2]Br4, which bear a polycationic core and a neutral shell of Fréchet-type poly(benzyl aryl ether) dendrons, have been investigated by means of dendritic wedges [3]Br2 and [4]Br, that resemble one of

  2. Magnetic properties of mixed spin (1, 3/2) Ising nanoparticles with core–shell structure

    International Nuclear Information System (INIS)

    Deviren, Bayram; Şener, Yunus

    2015-01-01

    The magnetic properties of mixed spin-1 and spin-3/2 Ising nanoparticles with core/shell structure are studied by using the effective-field theory with correlations. We investigate the thermal variations of the core, shell and total magnetizations and the Q-, R-, P-, S-, N- and L-types of compensation behavior in Néel classification nomenclature exists in the system. The effects of the crystal-field, core and shell interactions and interface coupling, on the phase diagrams are investigated in detail and the obtained phase diagrams are presented in three different planes. The system exhibits both second- and first-order phase transitions besides tricritical point, double critical end point, triple point and critical end point depending on the appropriate values of the interaction parameters. The system strongly affected by the surface situations and some characteristic phenomena are found depending on the ratio of the physical parameters in the surface shell and the core. - Highlights: • Magnetic properties of mixed spin (1, 3/2) Ising nanoparticles are investigated. • The system exhibits tricritical, double critical end, triple, critical end points. • Q-, R-, P-, S-, N- and L-types of compensation behavior are found. • Some characteristic phenomena are found depending on the interaction parameters. • Effects of crystal-field and bilinear interactions on the system are examined

  3. Magnetic properties of mixed spin (1, 3/2) Ising nanoparticles with core–shell structure

    Energy Technology Data Exchange (ETDEWEB)

    Deviren, Bayram, E-mail: bayram.deviren@nevsehir.edu.tr [Department of Physics, Nevsehir Hacı Bektaş Veli University, 50300 Nevşehir (Turkey); Şener, Yunus [Institute of Science, Department of Physics, Nevsehir Hacı Bektaş Veli University, 50300 Nevşehir (Turkey)

    2015-07-15

    The magnetic properties of mixed spin-1 and spin-3/2 Ising nanoparticles with core/shell structure are studied by using the effective-field theory with correlations. We investigate the thermal variations of the core, shell and total magnetizations and the Q-, R-, P-, S-, N- and L-types of compensation behavior in Néel classification nomenclature exists in the system. The effects of the crystal-field, core and shell interactions and interface coupling, on the phase diagrams are investigated in detail and the obtained phase diagrams are presented in three different planes. The system exhibits both second- and first-order phase transitions besides tricritical point, double critical end point, triple point and critical end point depending on the appropriate values of the interaction parameters. The system strongly affected by the surface situations and some characteristic phenomena are found depending on the ratio of the physical parameters in the surface shell and the core. - Highlights: • Magnetic properties of mixed spin (1, 3/2) Ising nanoparticles are investigated. • The system exhibits tricritical, double critical end, triple, critical end points. • Q-, R-, P-, S-, N- and L-types of compensation behavior are found. • Some characteristic phenomena are found depending on the interaction parameters. • Effects of crystal-field and bilinear interactions on the system are examined.

  4. Shell structure from N=Z (100Sn) to N>>Z (78Ni)

    International Nuclear Information System (INIS)

    Grawe, H.

    2003-01-01

    The shell structure of 100 Sn shows striking resemblance to 56 Ni one major shell below. Large-scale shell model calculations employing realistic interactions derived from effective NN potentials and allowing for up to 4p4h excitations of the 100 Sn core account very well for the spectroscopy of key neighbours 102,103 Sn, 98 Cd and 94 Ag, as inferred from level energies, isomerism, E2 strengths and Gamow-Teller (GT) decay of high-spin states. Recent β- decay studies of 101-104 Sn using the sulphurisation ISOL technique open the perspective to study the 100 Sn GT resonance. At N>>Z the persistence of the N=50 and the weakness of the N=40 shells are traced back to the monopole interaction in S=0 proton-neutron (πν) pairs of nucleons, a scenario which can be generalised to account for the new N=6,16(14),34(32) magicity in light neutron-rich nuclei. (orig.)

  5. Synthesis, characterization and nitrite ion sensing performance of reclaimable composite samples through a core-shell structure

    Science.gov (United States)

    Cui, Xiao; Yuqing, Zhao; Cui, Jiantao; Zheng, Qian; Bo, Wang

    2018-02-01

    The following paper reported and discussed a nitrite ion optical sensing platform based on a core-shell structure, using superamagnetic nanoparticles as the core, a silica molecular sieve MCM-41 as the shell and two rhodamine derivatives as probe, respectively. This superamagnetic core made this sensing platform reclaimable after finishing nitrite ion sensing procedure. This sensing platform was carefully characterized by means of electron microscopy images, porous structure analysis, magnetic response, IR spectra and thermal stability analysis. Detailed analysis suggested that the emission of these composite samples was quenchable by nitrite ion, showing emission turn off effect. A static sensing mechanism based on an additive reaction between chemosensors and nitrite ion was proposed. These composite samples followed Demas quenching equation against different nitrite ion concentrations. Limit of detection value was obtained as low as 0.4 μM. It was found that, after being quenched by nitrite ion, these composite samples could be reclaimed and recovered by sulphamic acid, confirming their recyclability.

  6. Electron scattering and nuclear structure

    International Nuclear Information System (INIS)

    Wolynec, E.

    1985-01-01

    A review of the historical development and the theory necessary to the interpretation of the experimental results is made. Some measurement techniques, experimental results and the technique of analysis of these data are presented. Future perspectives, due to the appearence of continous electron current accelerators, in this field of study are discussed. (L.C.) [pt

  7. Electron gun controlled smart structure

    Science.gov (United States)

    Martin, Jeffrey W.; Main, John Alan; Redmond, James M.; Henson, Tammy D.; Watson, Robert D.

    2001-01-01

    Disclosed is a method and system for actively controlling the shape of a sheet of electroactive material; the system comprising: one or more electrodes attached to the frontside of the electroactive sheet; a charged particle generator, disposed so as to direct a beam of charged particles (e.g. electrons) onto the electrode; a conductive substrate attached to the backside of the sheet; and a power supply electrically connected to the conductive substrate; whereby the sheet changes its shape in response to an electric field created across the sheet by an accumulation of electric charge within the electrode(s), relative to a potential applied to the conductive substrate. Use of multiple electrodes distributed across on the frontside ensures a uniform distribution of the charge with a single point of e-beam incidence, thereby greatly simplifying the beam scanning algorithm and raster control electronics, and reducing the problems associated with "blooming". By placing a distribution of electrodes over the front surface of a piezoelectric film (or other electroactive material), this arrangement enables improved control over the distribution of surface electric charges (e.g. electrons) by creating uniform (and possibly different) charge distributions within each individual electrode. Removal or deposition of net electric charge can be affected by controlling the secondary electron yield through manipulation of the backside electric potential with the power supply. The system can be used for actively controlling the shape of space-based deployable optics, such as adaptive mirrors and inflatable antennae.

  8. Eosin-Y sensitized core-shell TiO2-ZnO nano-structured photoanodes for dye-sensitized solar cell applications.

    Science.gov (United States)

    Manikandan, V S; Palai, Akshaya K; Mohanty, Smita; Nayak, Sanjay K

    2018-06-01

    In the current investigation, TiO 2 and TiO 2 -ZnO (core-shell) spherical nanoparticles were synthesized by simple combined hydrolysis and refluxing method. A TiO 2 core nanomaterial on the shell material of ZnO was synthesized by utilizing variable ratios of ZnO. The structural characterization of TiO 2 -ZnO core/shell nanoparticles were done by XRD analysis. The spherical structured morphology of the TiO 2 -ZnO has been confirmed through field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) studies. The UV-visible spectra of TiO 2 -ZnO nanostructures were also compared with the pristine TiO 2 to investigate the shift of wavelength. The TiO 2 -ZnO core/shell nanoparticles at the interface efficiently collect the photogenarated electrons from ZnO and also ZnO act a barrier for reduced charge recombination of electrolyte and dye-nanoparticles interface. This combination improved the light absorption which induced the charge transfer ability and dye loading capacity of core-shell nanoparticles. An enhancement in the short circuit current (J sc ) from 1.67 mA/cm 2 to 2.1 mA/cm 2 has been observed for TiO 2 -ZnObased photoanode (with platinum free counter electrode), promises an improvement in the energy conversion efficiency by 57% in comparison with that of the DSSCs based on the pristine TiO 2 . Henceforth, TiO 2 -ZnO photoelectrode in ZnO will effectively act as barrier at the interface of TiO 2 -ZnO and TiO 2 , ensuring the potential for DSSC application. Copyright © 2018 Elsevier B.V. All rights reserved.

  9. Measurement of differential incoherent scattering cross-sections of 145 keV photons from K-shell electrons

    Energy Technology Data Exchange (ETDEWEB)

    Acharya, V B; Ghumman, B S [Punjabi Univ., Patiala (India). Dept. of Physics

    1980-06-01

    Differential cross-sections for incoherent scattering of 145 keV photons from K-shell electrons of tin, silver and molybdenum have been measured at 110deg to investigate the effect of electron binding on differential cross-sections in the low energy region. The incoherent scattered photons are selected in coincidence with X-rays which follow the vacancies caused by the ejection of the electrons. NaI(Tl) scintillators are used for the detection of scattered photons and emitted X-rays. The experimental results are compared with the available theoretical data.

  10. Structural performance of a multipurpose canister shell for HLNW under normal handling conditions

    International Nuclear Information System (INIS)

    Ladkany, S.G.; Rajagopalan, R.

    1994-01-01

    A Multipurpose Canister (MPC) is analyzed for critical stresses that occur during normal handling conditions and accidental scenarios. Linear and Non-linear Finite Element Analysis is performed and the stresses at various critical locations in the MPC and its weldments are studied extensively. Progressive failure analysis of the MPC's groove and fillet welds, is presented. The structural response of the MPC to dynamic lifting loads, to loads resulting from an accidental slippage of a crane cable carrying the MPC, and from the impact between two canisters, is evaluated. Nonlinear structural analysis is used in the evaluation of the local buckling and the ultimate failure phenomena in the shell when the steel is in the strain hardening state during impact. Results make a case for increasing the thickness of the shell and all the welds

  11. Nonobservable nature of the nuclear shell structure: Meaning, illustrations, and consequences

    Science.gov (United States)

    Duguet, T.; Hergert, H.; Holt, J. D.; Somà, V.

    2015-09-01

    Background: The concept of single-nucleon shells constitutes a basic pillar of our understanding of nuclear structure. Effective single-particle energies (ESPEs) introduced by French [Proceedings of the International School of Physics "Enrico Fermi," Course XXXVI, Varenna 1965, edited by C. Bloch (Academic Press, New York, 1966)] and Baranger [Nucl. Phys. A 149, 225 (1970), 10.1016/0375-9474(70)90692-5] represent the most appropriate tool to relate many-body observables to a single-nucleon shell structure. As briefly discussed in Duguet and Hagen [Phys. Rev. C 85, 034330 (2012), 10.1103/PhysRevC.85.034330], the dependence of ESPEs on one-nucleon transfer probability matrices makes them purely theoretical quantities that "run" with the nonobservable resolution scale λ employed in the calculation. Purpose: Given that ESPEs provide a way to interpret the many-body problem in terms of simpler theoretical ingredients, the goal is to specify the terms, i.e., the exact sense and conditions, in which this interpretation can be conducted meaningfully. Methods: While the nuclear shell structure is both scale and scheme dependent, the present study focuses on the former. A detailed discussion is provided to illustrate the scale (in)dependence of observables and nonobservables and the reasons why ESPEs, i.e., the shell structure, belong to the latter category. State-of-the-art multireference in-medium similarity renormalization group and self-consistent Gorkov Green's function many-body calculations are employed to corroborate the formal analysis. This is done by comparing the behavior of several observables and of nonobservable ESPEs (and spectroscopic factors) under (quasi) unitary similarity renormalization group transformations of the Hamiltonian parametrized by the resolution scale λ . Results: The formal proofs are confirmed by the results of ab initio many-body calculations in their current stage of implementation. In practice, the unitarity of the similarity

  12. Carbon K-shell excitation in small molecules by high-resolution electron impact

    International Nuclear Information System (INIS)

    Tronc, M.; King, G.C.; Read, F.H.

    1979-01-01

    The excitation of 1s carbon electrons has been observed in C0, CH 4 , CF4, C0 2 , COS, C 2 H 2 and C 2 H 4 by means of the electron energy-loss technique with high resolution (70 meV in the 300 eV excitation energy range) and at an incident electron energy of 1.5 keV. The energies, widths and vibrational structures of excited states corresponding to the promotion of 1s carbon electrons to unoccupied valence and Rydberg orbitals have been obtained. The validity of the equivalent-core model, and the role of resonances caused by potential barriers, are discussed. (author)

  13. Structure of neutron-rich nuclei around the N = 50 shell-gap closure

    Science.gov (United States)

    Faul, T.; Duchêne, G.; Thomas, J.-C.; Nowacki, F.; Huyse, M.; Van Duppen, P.

    2010-04-01

    The structure of neutron-rich nuclei in the vicinity of 78Ni have been investigated via the β-decay of 71,73,75Cu isotopes (ISOLDE, CERN). Experimental results have been compared with shell-model calculations performed with the ANTOINE code using a large (2p3/21f5/22p1/21g9/2) valence space and a 56/28Ni28 core.

  14. On the absence of an α-nucleus structure in a two-centre shell model

    International Nuclear Information System (INIS)

    Gupta, R.K.; Sharma, M.K.; Antonenko, N.V.; Scheid, W.

    1999-01-01

    The two-centre shell model, used within the Strutinsky macro-microscopic method, is a valid prescription for calculating adiabatic or diabatic potential energy surfaces. It is shown, however, that this model does not contain the appropriate α-nucleus structure effects, very much required for collisions between light nuclei. A possible way to incorporate such effects is suggested. (author). Letter-to-the-editor

  15. Low power multiple shell fusion targets for use with electron and ion beams

    International Nuclear Information System (INIS)

    Lindl, J.D.; Bangerter, R.O.

    1975-01-01

    Use of double shell targets with a separate low Z, low density ablator at large radius for the outer shell, reduces the focusing and power requirements while maintaining reasonable aspect ratios. A high Z, high density pusher shell is placed at a much smaller radius in order to obtain an aspect ratio small enough to protect against fluid instability. Velocity multiplication between these shells further lowers the power requirements. Careful tuning of the power profile and intershell density results in a low entropy implosion which allows breakeven at low powers. Ion beams appear to be a promising power source and breakeven at 10-20 Terrawatts with 10 MeV alpha particles appears feasible. Predicted performance of targets with various energy sources is shown and comparison is made with single shell targets

  16. Evolution of Structure in Nuclei: Meditation by Sub-Shell Modifications and Relation to Binding Energies

    Science.gov (United States)

    Casten, R. F.; Cakirli, R. B.

    2009-03-01

    Understanding the development of configuration mixing, coherence, collectivity, and deformation in nuclei is one of the crucial challenges in nuclear structure physics, and one which has become all the more important with the advent of next generation facilities for the study of exotic nuclei. We will discuss recent work on phase/shape transitional behavior in nuclei, and the role of changes in sub-shell structure in mediating such transitional regions. We will also discuss a newly found, much deeper, link between nuclear structure and nuclear binding energies.

  17. Design of cryogenic tanks for space vehicles shell structures analytical modeling

    Science.gov (United States)

    Copper, Charles; Mccarthy, K.; Pilkey, W. D.; Haviland, J. K.

    1991-01-01

    The initial objective was to study the use of superplastically formed corrugated hat section stringers and frames in place of integrally machined stringers over separate frames for the tanks of large launch vehicles subjected to high buckling loads. The ALS was used as an example. The objective of the follow-on project was to study methods of designing shell structures subjected to severe combinations of structural loads and thermal gradients, with emphasis on new combinations of structural arrangements and materials. Typical applications would be to fuselage sections of high speed civil transports and to cryogenic tanks on the National Aerospace Plane.

  18. STRUCTURAL STABILITY AND ELECTRONIC STRUCTURE OF ...

    African Journals Online (AJOL)

    2012-12-31

    Dec 31, 2012 ... may be applications at high temperature strength and corrosion ... B2 structure, like that found in cesium-chloride (CsCl) and chemical formula RM, where R denotes a rare - earth element and M denotes a late transition metal ...

  19. Synthesis of TiO2/Bi2S3 heterojunction with a nuclear-shell structure and its high photocatalytic activity

    International Nuclear Information System (INIS)

    Lu, Juan; Han, Qiaofeng; Wang, Zuoshan

    2012-01-01

    Highlights: ► Bi 2 S 3 was doped into TiO 2 and it was clearly proved by the expander of the crystalline lattice in XRD result. ► As-prepared TiO 2 /Bi 2 S 3 heterojunctions have a nuclear-shell structure which has not been reported. ► As-prepared TiO 2 /Bi 2 S 3 heterojunctions have the excellent photocatalytic activity. -- Abstract: TiO 2 /Bi 2 S 3 heterojunctions with a nuclear-shell structure were prepared by the coprecipitation method. The products were characterized by X-ray diffraction analysis, Raman spectra, transmission electron microscope images and energy dispersion X-ray spectra. Results showed that as-prepared Bi 2 S 3 was urchin-like, made from many nanorods, and TiO 2 /Bi 2 S 3 heterojunctions have a similar nuclear-shell structure, with Bi 2 S 3 as the shell and TiO 2 as the nuclear. The photocatalytic experiments performed under UV irradiation using methyl orange as the pollutant revealed that the photocatalytic activity of TiO 2 could be improved by introduction of an appropriate amount of Bi 2 S 3 . However, excessive amount of Bi 2 S 3 would result in the decrease of photocatalytic activity of TiO 2 . The relative mechanism was proposed.

  20. Composites Based on Core-Shell Structured HBCuPc@CNTs-Fe3O4 and Polyarylene Ether Nitriles with Excellent Dielectric and Mechanical Properties

    Science.gov (United States)

    Pu, Zejun; Zhong, Jiachun; Liu, Xiaobo

    2017-10-01

    Core-shell structured magnetic carbon nanotubes (CNTs-Fe3O4) coated with hyperbranched copper phthalocyanine (HBCuPc) (HBCuPc@CNTs-Fe3O4) hybrids were prepared by the solvent-thermal method. The results indicated that the HBCuPc molecules were decorated on the surface of CNTs-Fe3O4 through coordination behavior of phthalocyanines, and the CNTs-Fe3O4 core was completely coaxial wrapped by a functional intermediate HBCuPc shell. Then, polymer-based composites with a relatively high dielectric constant and low dielectric loss were fabricated by using core-shell structured HBCuPc@CNTs-Fe3O4 hybrids as fillers and polyarylene ether nitriles (PEN) as the polymer matrix. The cross-sectional scanning electron microscopy (SEM) images of composites showed that there is almost no agglomeration and internal delamination. In addition, the rheological analysis reveals that the core-shell structured HBCuPc@CNTs-Fe3O4 hybrids present better dispersion and stronger interface adhesion with the PEN matrix than CNTs-Fe3O4, thus resulting in significant improvement of the mechanical, thermal and dielectric properties of polymer-based composites.

  1. Preparation of TiC/W core–shell structured powders by one-step activation and chemical reduction process

    International Nuclear Information System (INIS)

    Ding, Xiao-Yu; Luo, Lai-Ma; Huang, Li-Mei; Luo, Guang-Nan; Zhu, Xiao-Yong; Cheng, Ji-Gui; Wu, Yu-Cheng

    2015-01-01

    Highlights: • A novel wet chemical method was used to prepare TiC/W core–shell structure powders. • TiC nanoparticles were well-encapsulated by W shells. • TiC phase was present in the interior of tungsten grains. - Abstract: In the present study, one-step activation and chemical reduction process as a novel wet-chemical route was performed for the preparation of TiC/W core–shell structured ultra-fine powders. The XRD, FE-SEM, TEM and EDS results demonstrated that the as-synthesized powders are of high purity and uniform with a diameter of approximately 500 nm. It is also found that the TiC nanoparticles were well-encapsulated by W shells. Such a unique process suggests a new method for preparing X/W (X refers the water-insoluble nanoparticles) core–shell nanoparticles with different cores

  2. Rapid Synthesis and Formation Mechanism of Core-Shell-Structured La-Doped SrTiO3 with a Nb-Doped Shell

    Directory of Open Access Journals (Sweden)

    Nam-Hee Park

    2015-07-01

    Full Text Available To provide a convenient and practical synthesis process for metal ion doping on the surface of nanoparticles in an assembled nanostructure, core-shell-structured La-doped SrTiO3 nanocubes with a Nb-doped surface layer were synthesized via a rapid synthesis combining a rapid sol-precipitation and hydrothermal process. The La-doped SrTiO3 nanocubes were formed at room temperature by a rapid dissolution of NaOH pellets during the rapid sol-precipitation process, and the Nb-doped surface (shell along with Nb-rich edges formed on the core nanocubes via the hydrothermal process. The formation mechanism of the core-shell-structured nanocubes and their shape evolution as a function of the Nb doping level were investigated. The synthesized core-shell-structured nanocubes could be arranged face-to-face on a SiO2/Si substrate by a slow evaporation process, and this nanostructured 10 μm thick thin film showed a smooth surface.

  3. Investigation of CuInSe{sub 2} nanowire arrays with core–shell structure electrodeposited at various duty cycles into anodic alumina templates

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Yu-Song [Institute of Microelectronics, Department of Electrical Engineering, National Cheng-Kung University, Tainan 701, Taiwan (China); Wang, Na-Fu; Tsai, Yu-Zen [Department of Electronic Engineering, Cheng Shiu University, 840 Chengcing Rd., Niaosong District, Kaohsiung City 833, Taiwan (China); Lin, Jia-Jun [Institute of Microelectronics, Department of Electrical Engineering, National Cheng-Kung University, Tainan 701, Taiwan (China); Houng, Mau-Phon, E-mail: mphoung@eembox.ncku.edu.tw [Institute of Microelectronics, Department of Electrical Engineering, National Cheng-Kung University, Tainan 701, Taiwan (China)

    2017-02-28

    Highlights: • The present paper reports that CuInSe2 NW arrays were fabricated through pulsed electrode position onto an AAO template with various duty cycles, and a pore-filling ratio of approximately 92% was achieved. • GIXRD patterns showed that all CuInSe2 NW arrays were chalcopyrite and SAED images confirmed that the CuInSe2 NWs were polycrystalline. • PEDOT/CuInSe2 NW core–shell arrays were fabricated using surfactant-modified CuInSe2 NW surfaces showing the lotus effect. • Current–voltage plots revealed that the CuInSe2 NW arrays were p-type semiconductors; moreover, the core–shell structure improved the diode ideality factor from 3.91 to 2.63. - Abstract: Copper indium selenide (CuInSe{sub 2}) nanowire (NW) arrays were prepared at various electrolyte duty cycles by filling anodic alumina templates through the pulsed electrodeposition technique. X-ray diffraction and scanning electron microscopy (SEM) images showed that the nucleation mechanism of CuInSe{sub 2} NW arrays was affected by the electrodeposition duty cycle. Moreover, SEM images showed that the diameter and length of the NWs were 80 nm and 2 μm, respectively. Furthermore, PEDOT/CuInSe{sub 2} NW core–shell arrays were fabricated using surfactant-modified CuInSe{sub 2} NW surfaces showing the lotus effect. Transmission electron microscopy images confirmed that a core–shell structure was achieved. Current–voltage plots revealed that the CuInSe{sub 2} NW arrays were p-type semiconductors; moreover, the core–shell structure improved the diode ideality factor from 3.91 to 2.63.

  4. Investigation of CuInSe2 nanowire arrays with core–shell structure electrodeposited at various duty cycles into anodic alumina templates

    International Nuclear Information System (INIS)

    Cheng, Yu-Song; Wang, Na-Fu; Tsai, Yu-Zen; Lin, Jia-Jun; Houng, Mau-Phon

    2017-01-01

    Highlights: • The present paper reports that CuInSe2 NW arrays were fabricated through pulsed electrode position onto an AAO template with various duty cycles, and a pore-filling ratio of approximately 92% was achieved. • GIXRD patterns showed that all CuInSe2 NW arrays were chalcopyrite and SAED images confirmed that the CuInSe2 NWs were polycrystalline. • PEDOT/CuInSe2 NW core–shell arrays were fabricated using surfactant-modified CuInSe2 NW surfaces showing the lotus effect. • Current–voltage plots revealed that the CuInSe2 NW arrays were p-type semiconductors; moreover, the core–shell structure improved the diode ideality factor from 3.91 to 2.63. - Abstract: Copper indium selenide (CuInSe 2 ) nanowire (NW) arrays were prepared at various electrolyte duty cycles by filling anodic alumina templates through the pulsed electrodeposition technique. X-ray diffraction and scanning electron microscopy (SEM) images showed that the nucleation mechanism of CuInSe 2 NW arrays was affected by the electrodeposition duty cycle. Moreover, SEM images showed that the diameter and length of the NWs were 80 nm and 2 μm, respectively. Furthermore, PEDOT/CuInSe 2 NW core–shell arrays were fabricated using surfactant-modified CuInSe 2 NW surfaces showing the lotus effect. Transmission electron microscopy images confirmed that a core–shell structure was achieved. Current–voltage plots revealed that the CuInSe 2 NW arrays were p-type semiconductors; moreover, the core–shell structure improved the diode ideality factor from 3.91 to 2.63.

  5. Damage detection strategies for aircraft shell-like structures based on propagation guided elastic waves

    International Nuclear Information System (INIS)

    Zak, A; Ostachowicz, W; Krawczuk, M

    2011-01-01

    Damage of aircraft structural elements in any form always present high risks. Failures of these elements can be caused by various reasons including material fatigue or impact leading to damage initiation and growth. Detection of these failures at their earliest stage of development, estimation of their size and location, are one of the most crucial factors for each damage detection method. Structural health monitoring strategies based on propagation of guided elastic waves in structures and wave interaction with damage related discontinuities are very promising tools that offer not only damage detection capabilities, but are also meant to provide precise information about the state of the structures and their remaining lifetime. Because of that various techniques are employed to simulate and mimic the wave-discontinuity interactions. The use of various types of sensors, their networks together with sophisticated contactless measuring techniques are investigated both numerically and experimentally. Certain results of numerical simulations obtained by the use of the spectral finite element method are presented by the authors and related with propagation of guided elastic waves in shell-type aircraft structures. Two types of structures are considered: flat 2D panels with or without stiffeners and 3D shell structures. The applicability of two different damage detection approaches is evaluated in order to detect and localise damage in these structures. Selected results related with the use of laser scanning vibrometry are also presented and discussed by the authors.

  6. Electronic structure of metallic glasses

    International Nuclear Information System (INIS)

    Oelhafen, P.; Lapka, R.; Gubler, U.; Krieg, J.; DasGupta, A.; Guentherodt, H.J.; Mizoguchi, T.; Hague, C.; Kuebler, J.; Nagel, S.R.

    1981-01-01

    This paper is organized in six sections and deals with (1) the glassy transition metal alloys, their d-band structure, the d-band shifts on alloying and their relation to the alloy heat of formation (ΔH) and the glass forming ability, (2) the glass to crystal phase transition viewed by valence band spectroscopy, (3) band structure calculations, (4) metallic glasses prepared by laser glazing, (5) glassy normal metal alloys, and (6) glassy hydrides

  7. Electronic structure and tautomerism of aryl ketones

    International Nuclear Information System (INIS)

    Novak, Igor; Klasinc, Leo; Šket, Boris; McGlynn, S.P.

    2015-01-01

    Graphical abstract: Photoelectron spectroscopy, tautomerism. - Highlights: • UV photoelectron spectroscopy of aryl ketones. • The relative stability of tautomers and their electronic structures. • The factors influencing tautomerism. - Abstract: The electronic structures of several aryl ketones (AK) and their α-halo derivatives have been studied by UV photoelectron spectroscopy (UPS). The relative stabilities of keto–enol tautomers have been determined using high-level ab initio calculations and the results were used in the analysis of UPS spectra. The main features of electronic structure and tautomerism of the AK derivatives are discussed

  8. Phenomenology of the electron structure function

    International Nuclear Information System (INIS)

    Slominski, W.; Szwed, J.

    2001-01-01

    The advantages of introducing the electron structure function (ESF) in electron induced processes are demonstrated. Contrary to the photon structure function it is directly measured in such processes. At present energies, a simultaneous analysis of both the electron and the photon structure functions gives an important test of the experimentally applied methods. Estimates of the ESF at LEP momenta are given. At very high momenta contributions from W and Z bosons together with γ-Z interference can be observed. Predictions for the next generation of experiments are given. (orig.)

  9. Electronic structure and tautomerism of aryl ketones

    Energy Technology Data Exchange (ETDEWEB)

    Novak, Igor, E-mail: inovak@csu.edu.au [Charles Sturt University, POB 883, Orange, NSW 2800 (Australia); Klasinc, Leo, E-mail: klasinc@irb.hr [Physical Chemistry Department, Ruđer Bošković Institute, HR-10002 Zagreb (Croatia); Šket, Boris, E-mail: Boris.Sket@fkkt.uni-lj.si [Faculty of Chemistry and Chemical Technology, University of Ljubljana, SI-1000 (Slovenia); McGlynn, S.P., E-mail: sean.mcglynn@chemgate.chem.lsu.edu [Louisiana State University, Baton Rouge, LA 70803 (United States)

    2015-07-15

    Graphical abstract: Photoelectron spectroscopy, tautomerism. - Highlights: • UV photoelectron spectroscopy of aryl ketones. • The relative stability of tautomers and their electronic structures. • The factors influencing tautomerism. - Abstract: The electronic structures of several aryl ketones (AK) and their α-halo derivatives have been studied by UV photoelectron spectroscopy (UPS). The relative stabilities of keto–enol tautomers have been determined using high-level ab initio calculations and the results were used in the analysis of UPS spectra. The main features of electronic structure and tautomerism of the AK derivatives are discussed.

  10. Uniform formation of Au coated polystyrene core-shell structure using metallization process

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyoungseob; Koo, Jonghyun; Roh, Yonghan, E-mail: yhroh@skku.edu

    2011-08-01

    There are several methods for the fabrication of core-shell particles, including chemical reduction and self-assembly. In this study, the chemical reduction method was used to fabricate 100 nm, Au-coated polystyrene nanoparticles. The formation of the gold layer was based on the increase of gold coverage by the reaction with aniline and HAuCl{sub 4}. This method allowed for efficient control of the gold coverage and led to relatively stable products. The formation of Au clusters on the surface of the 100 nm polystyrene beads was characterized by scanning electron microscope and high resolution tunneling electron microscope. As a result, the Au-coated nanoparticles can be used in various applications such as surface plasmon resonators, drug delivery systems and electronic optical devices.

  11. Yolk-shell structured composite for fast and selective lithium ion sieving.

    Science.gov (United States)

    Li, Na; Lu, Deli; Zhang, Jinlong; Wang, Lingzhi

    2018-06-15

    Yolk-shell structured C@Li 4 Ti 5 O 12 microspheres composed of carbon core (ca. 500 nm) and sea urchin-like Li 4 Ti 5 O 12 shell (ca. 400-500 nm) are formed by hydrothermally treating the core-shell structured C@TiO 2 in the EtOH/H 2 O solution of LiOH and calcining it in N 2 atmosphere. Yolk-shell structured TiO 2 -type lithium ion sieve is further transformed from C@Li 4 Ti 5 O 12 through the acid treatment, which have a high specific surface area of 201.74 m 2 /g. The composite shows adsorption capacity towards Li + proportional to the pH value in the range of 7-13. The adsorption reaches equilibrium within 2 h with a high equilibrium adsorption capacity of 28.46 mg/g under alkaline conditions, which is ca. 8 times the value of ordinary TiO 2 lithium ion sieve with comparable size and surface area, demonstrating the enhanced adsorption is attributed to the generation of more accessible surficial voids by replacing internal part with light carbon core. The adsorption follows Freundlich and pseudo-second-order kinetic models with a high rate constant of 0.015 g/(mg·min). The selective adsorption to Li + is verified in the presence of K + , Na + , Ca 2+ and Mg 2+ . Copyright © 2018 Elsevier Inc. All rights reserved.

  12. The influence of the shell closure on the microscopic structure of even-even Hg isotopes

    International Nuclear Information System (INIS)

    Burghardt, A.J.C.

    1989-01-01

    Muonic X-ray data were obtained for 198 200 202 204 Hg at high-intensity muon-beam facility of SIN and an electron-scattering study was performed on 204 Hg with the 500 MeV, high-resolution electron-scattering facility of NIKHEF-K in a q-range from 0.4 to 2.9 fm -1 . The combined analysis of the elastic electron-scattering and muonic X-ray data has yielded the ground-state charge distribution of 204 Hg. Hartree-Fock calculations with four different interactions, with and without the inclusion of pairing correlations, are compared to this experimental result. The charge-density difference between 206 Pb (determined elsewhere) and 204 Hg is then used ot investigate the filling of the last proton orbit before the Z=82 shell closure, the 3s 1/2 orbit. The interpretation of this difference, also in terms of Hartree-Fock calculations, is discussed in conjunction with the earlier study of Frois et al. concerning 206 Pb and 205 Tl. Many excited states have been observed in the spectra of 204 Hg. The experimental excitation energies and the spins and parities assigned to a number of states are presented. From the cross-section data for these states transition charge distributions have been extracted. Shell-model predictions are compared with the observed level scheme and the shell-model calculation performed by Poppelier is used to interpret transition charge distributions of six states. 101 refs.; 32 figs.; 41 figs

  13. Iron Oxide Nanoparticles: Tunable Size Synthesis and Analysis in Terms of the Core-Shell Structure and Mixed Coercive Model

    Science.gov (United States)

    Phong, P. T.; Oanh, V. T. K.; Lam, T. D.; Phuc, N. X.; Tung, L. D.; Thanh, Nguyen T. K.; Manh, D. H.

    2017-04-01

    Iron oxide nanoparticles (NPs) are currently a very active research field. To date, a comprehensive study of iron oxide NPs is still lacking not only on the size dependence of structural phases but also in the use of an appropriate model. Herein, we report on a systematic study of the structural and magnetic properties of iron oxide NPs prepared by a co-precipitation method followed by hydrothermal treatment. X-ray diffraction and transmission electron microscopy reveal that the NPs have an inverse spinel structure of iron oxide phase (Fe3O4) with average crystallite sizes ( D XRD) of 6-19 nm, while grain sizes ( D TEM) are of 7-23 nm. In addition, the larger the particle size, the closer the experimental lattice constant value is to that of the magnetite structure. Magnetic field-dependent magnetization data and analysis show that the effective anisotropy constants of the Fe3O4 NPs are about five times larger than that of their bulk counterpart. Particle size ( D) dependence of the magnetization and the non-saturating behavior observed in applied fields up to 50 kOe are discussed using the core-shell structure model. We find that with decreasing D, while the calculated thickness of the shell of disordered spins ( t ˜ 0.3 nm) remains almost unchanged, the specific surface areas S a increases significantly, thus reducing the magnetization of the NPs. We also probe the coercivity of the NPs by using the mixed coercive Kneller and Luborsky model. The calculated results indicate that the coercivity rises monotonously with the particle size, and are well matched with the experimental ones.

  14. Measurements of L shell X-ray yields of thick Ag target by 6–29 keV electron impact

    International Nuclear Information System (INIS)

    Zhao, J.L.; Tian, L.X.; Li, X.L.; An, Z.; Zhu, J.J.; Liu, M.T.

    2015-01-01

    In this paper, the L shell X-ray yields for a thick Ag target have been measured at incident electron energies of 6–29 keV. The experimental values are compared with the Monte Carlo simulation results that are obtained by using the PENELOPE code, in which the inner-shell ionization cross sections by electron impact calculated in the theoretical frame of distorted wave Born approximation are used. The experimental and simulation values are in agreement with ∼10% difference. Meanwhile, the L shell X-ray production cross sections are also obtained based on the measured L shell X-ray yields for a thick Ag target in this paper, and are compared with other experimental Ag L shell X-ray production cross section data by electron and positron impact measured previously and some theoretical models. Some factors that could affect these comparisons are also discussed in this paper. - Highlights: • We measured L shell X-ray yields of thick Ag target by 6–29 keV electrons. • Our measured X-ray yields are in good agreement with the MC results with ∼10%. • L shell production cross sections are obtained based on the measured X-ray yields. • L shell production cross sections obtained are in good agreement with theories

  15. Epitaxial graphene electronic structure and transport

    International Nuclear Information System (INIS)

    De Heer, Walt A; Berger, Claire; Wu Xiaosong; Sprinkle, Mike; Hu Yike; Ruan Ming; First, Phillip N; Stroscio, Joseph A; Haddon, Robert; Piot, Benjamin; Faugeras, Clement; Potemski, Marek; Moon, Jeong-Sun

    2010-01-01

    Since its inception in 2001, the science and technology of epitaxial graphene on hexagonal silicon carbide has matured into a major international effort and is poised to become the first carbon electronics platform. A historical perspective is presented and the unique electronic properties of single and multilayered epitaxial graphenes on electronics grade silicon carbide are reviewed. Early results on transport and the field effect in Si-face grown graphene monolayers provided proof-of-principle demonstrations. Besides monolayer epitaxial graphene, attention is given to C-face grown multilayer graphene, which consists of electronically decoupled graphene sheets. Production, structure and electronic structure are reviewed. The electronic properties, interrogated using a wide variety of surface, electrical and optical probes, are discussed. An overview is given of recent developments of several device prototypes including resistance standards based on epitaxial graphene quantum Hall devices and new ultrahigh frequency analogue epitaxial graphene amplifiers.

  16. On the interactions between energetic electrons and lightning whistler waves observed at high L-shells on Van Allen Probes

    Science.gov (United States)

    Zheng, H.; Holzworth, R. H., II; Brundell, J. B.; Hospodarsky, G. B.; Jacobson, A. R.; Fennell, J. F.; Li, J.

    2017-12-01

    Lightning produces strong broadband radio waves, called "sferics", which propagate in the Earth-ionosphere waveguide and are detected thousands of kilometers away from their source. Global real-time detection of lightning strokes including their time, location and energy, is conducted with the World Wide Lightning Location Network (WWLLN). In the ionosphere, these sferics couple into very low frequency (VLF) whistler waves which propagate obliquely to the Earth's magnetic field. A good match has previously been shown between WWLLN sferics and Van Allen Probes lightning whistler waves. It is well known that lightning whistler waves can modify the distribution of energetic electrons in the Van Allen belts by pitch angle scattering into the loss cone, especially at low L-Shells (referred to as LEP - Lightning-induced Electron Precipitation). It is an open question whether lightning whistler waves play an important role at high L-shells. The possible interactions between energetic electrons and lightning whistler waves at high L-shells are considered to be weak in the past. However, lightning is copious, and weak pitch angle scattering into the drift or bounce loss cone would have a significant influence on the radiation belt populations. In this work, we will analyze the continuous burst mode EMFISIS data from September 2012 to 2016, to find out lightning whistler waves above L = 3. Based on that, MAGEIS data are used to study the related possible wave-particle interactions. In this talk, both case study and statistical analysis results will be presented.

  17. a-Axis GaN/AlN/AlGaN Core-Shell Heterojunction Microwires as Normally Off High Electron Mobility Transistors.

    Science.gov (United States)

    Song, Weidong; Wang, Rupeng; Wang, Xingfu; Guo, Dexiao; Chen, Hang; Zhu, Yuntao; Liu, Liu; Zhou, Yu; Sun, Qian; Wang, Li; Li, Shuti

    2017-11-29

    Micro/nanowire-based devices have been envisioned as a promising new route toward improved electronic and optoelectronic applications, which attracts considerable research interests. However, suffering from applicable strategies to synthesize uniform core-shell structures to meet the requirement for the investigations of electrical transport behaviors along the length direction or high electron mobility transistor (HEMT) devices, heterojunction wire-based electronics have been explored limitedly. In the present work, GaN/AlN/AlGaN core-shell heterojunction microwires on patterned Si substrates were synthesized without any catalyst via metalorganic chemical vapor deposition. The as-synthesized microwires had low dislocation, sharp, and uniform heterojunction interfaces. Electrical transport performances were evaluated by fabricating HEMTs on the heterojunction microwire channels. Results demonstrated that a normally off operation was achieved with a threshold voltage of 1.4 V, a high on/off current ratio of 10 8 , a transconductance of 165 mS/mm, and a low subthreshold swing of 81 mV/dec. The normally off operation may attribute to the weak polarization along semipolar facets of the heterojunction, which leads to weak constrain of 2DEG.

  18. The impact of core-shell nanotube structures on fracture in ceramic nanocomposites

    International Nuclear Information System (INIS)

    Liang, Xin; Yang, Yingchao; Lou, Jun; Sheldon, Brian W.

    2017-01-01

    Multi-wall carbon nanotubes (MWCNTs) can be used to create ceramic nanocomposites with improved fracture toughness. In the present work, atomic layer deposition (ALD) was employed to deposit thin oxide layers on MWCNTs. These core-shell structures were then used to create nanocomposites by using a polymer derived ceramic (PDC) to produce the matrix. Variations in both the initial MWCNT structure and the oxide layers led to substantial differences in fiber-pullout behavior. Single tube pullout tests also showed that the oxide coatings led to stronger bonding with the ceramic matrix. With high defect density MWCNTs, this led to shorter pull-out lengths which is consistent with the conventional understanding of fracture in ceramic matrix composites. However, with low defect density MWCNTs longer pullout lengths were observed with the oxide layers. To interpret the different trends that were observed, we believe that the ALD coatings should not be viewed simply as a means of altering the interfacial properties. Instead, the coated MWCNTs should be viewed as more complex core-shell fibers where both interface and internal properties can be controlled with the ALD layers. - Graphical abstract: Fracture properties of core-shell nanotubes reinforced ceramic nanocomposites.

  19. Structural aspects of the solvation shell of lysine and acetylated lysine: A Car-Parrinello and classical molecular dynamics investigation

    International Nuclear Information System (INIS)

    Carnevale, V.; Raugei, S.

    2009-01-01

    Lysine acetylation is a post-translational modification, which modulates the affinity of protein-protein and/or protein-DNA complexes. Its crucial role as a switch in signaling pathways highlights the relevance of charged chemical groups in determining the interactions between water and biomolecules. A great effort has been recently devoted to assess the reliability of classical molecular dynamics simulations in describing the solvation properties of charged moieties. In the spirit of these investigations, we performed classical and Car-Parrinello molecular dynamics simulations on lysine and acetylated-lysine in aqueous solution. A comparative analysis between the two computational schemes is presented with a focus on the first solvation shell of the charged groups. An accurate structural analysis unveils subtle, yet statistically significant, differences which are discussed in connection to the significant electronic density charge transfer occurring between the solute and the surrounding water molecules.

  20. Nuclear-electronic orbital reduced explicitly correlated Hartree-Fock approach: Restricted basis sets and open-shell systems

    International Nuclear Information System (INIS)

    Brorsen, Kurt R.; Sirjoosingh, Andrew; Pak, Michael V.; Hammes-Schiffer, Sharon

    2015-01-01

    The nuclear electronic orbital (NEO) reduced explicitly correlated Hartree-Fock (RXCHF) approach couples select electronic orbitals to the nuclear orbital via Gaussian-type geminal functions. This approach is extended to enable the use of a restricted basis set for the explicitly correlated electronic orbitals and an open-shell treatment for the other electronic orbitals. The working equations are derived and the implementation is discussed for both extensions. The RXCHF method with a restricted basis set is applied to HCN and FHF − and is shown to agree quantitatively with results from RXCHF calculations with a full basis set. The number of many-particle integrals that must be calculated for these two molecules is reduced by over an order of magnitude with essentially no loss in accuracy, and the reduction factor will increase substantially for larger systems. Typically, the computational cost of RXCHF calculations with restricted basis sets will scale in terms of the number of basis functions centered on the quantum nucleus and the covalently bonded neighbor(s). In addition, the RXCHF method with an odd number of electrons that are not explicitly correlated to the nuclear orbital is implemented using a restricted open-shell formalism for these electrons. This method is applied to HCN + , and the nuclear densities are in qualitative agreement with grid-based calculations. Future work will focus on the significance of nonadiabatic effects in molecular systems and the further enhancement of the NEO-RXCHF approach to accurately describe such effects

  1. Nuclear-electronic orbital reduced explicitly correlated Hartree-Fock approach: Restricted basis sets and open-shell systems

    Energy Technology Data Exchange (ETDEWEB)

    Brorsen, Kurt R.; Sirjoosingh, Andrew; Pak, Michael V.; Hammes-Schiffer, Sharon, E-mail: shs3@illinois.edu [Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Ave., Urbana, Illinois 61801 (United States)

    2015-06-07

    The nuclear electronic orbital (NEO) reduced explicitly correlated Hartree-Fock (RXCHF) approach couples select electronic orbitals to the nuclear orbital via Gaussian-type geminal functions. This approach is extended to enable the use of a restricted basis set for the explicitly correlated electronic orbitals and an open-shell treatment for the other electronic orbitals. The working equations are derived and the implementation is discussed for both extensions. The RXCHF method with a restricted basis set is applied to HCN and FHF{sup −} and is shown to agree quantitatively with results from RXCHF calculations with a full basis set. The number of many-particle integrals that must be calculated for these two molecules is reduced by over an order of magnitude with essentially no loss in accuracy, and the reduction factor will increase substantially for larger systems. Typically, the computational cost of RXCHF calculations with restricted basis sets will scale in terms of the number of basis functions centered on the quantum nucleus and the covalently bonded neighbor(s). In addition, the RXCHF method with an odd number of electrons that are not explicitly correlated to the nuclear orbital is implemented using a restricted open-shell formalism for these electrons. This method is applied to HCN{sup +}, and the nuclear densities are in qualitative agreement with grid-based calculations. Future work will focus on the significance of nonadiabatic effects in molecular systems and the further enhancement of the NEO-RXCHF approach to accurately describe such effects.

  2. Instructional Approach to Molecular Electronic Structure Theory

    Science.gov (United States)

    Dykstra, Clifford E.; Schaefer, Henry F.

    1977-01-01

    Describes a graduate quantum mechanics projects in which students write a computer program that performs ab initio calculations on the electronic structure of a simple molecule. Theoretical potential energy curves are produced. (MLH)

  3. Charge radii of magnesium isotopes by laser spectroscopy a structural study over the $sd$ shell

    CERN Multimedia

    Schug, M; Krieger, A R

    We propose to study the evolution of nuclear sizes and shapes over the magnesium chain by measuring the root-mean-square charge radii of $^{21 - 32}$Mg, essentially covering the entire $\\textit{sd}$ shell. Our goal is to detect the structural changes, which in the neutron-deficient isotopes may originate from clustering, in a way similar to neon, and on the neutron-rich side would characterize the transition to the "island of inversion". We will combine, for the first time, the sensitive $\\beta$-detection technique with traditional fluorescence spectroscopy for isotope-shift measurements and in such a way gain access to the exotic species near the ${N}$ = 8 and ${N}$ = 20 shell closures.

  4. Experimental and numerical modelling of ductile crack propagation in large-scale shell structures

    DEFF Research Database (Denmark)

    Simonsen, Bo Cerup; Törnquist, R.

    2004-01-01

    plastic and controlled conditions. The test specimen can be deformed either in combined in-plane bending and extension or in pure extension. Experimental results are described for 5 and 10 mm thick aluminium and steel plates. By performing an inverse finite-element analysis of the experimental results......This paper presents a combined experimental-numerical procedure for development and calibration of macroscopic crack propagation criteria in large-scale shell structures. A novel experimental set-up is described in which a mode-I crack can be driven 400 mm through a 20(+) mm thick plate under fully...... for steel and aluminium plates, mainly as curves showing the critical element deformation versus the shell element size. These derived crack propagation criteria are then validated against a separate set of experiments considering centre crack specimens (CCS) which have a different crack-tip constraint...

  5. Stress analysis of partial sphere used for bottom shell of off-shore structure

    International Nuclear Information System (INIS)

    Nishimaki, Ko; Matsumoto, Kohei; Hori, Tohru; Takeshita, Haruyuki; Iwata, Setsuo

    1976-01-01

    In the near future, various huge off-shore structures will be constructed. Concrete shall become a leading material in the structures, owing to its versatile properties. One of the limitations of concrete is its low tensile strength. The problem of low tensile strength of concrete is dealt with in main by two different methods: by applying prestressing and by designing the structural configuration so that no tensile stresses appear. In the paper, the authors discuss the application of partially spherical shell to huge off-shore structures. Structural analysis by using the finite element method were done in order to investigate the feasibility of the structure. The results were arranged as to certain parameters to derive design charts by which the stresses of check points can be presumed. Optimum shape is also discussed. (auth.)

  6. The Fabrication and High-Efficiency Electromagnetic Wave Absorption Performance of CoFe/C Core-Shell Structured Nanocomposites

    Science.gov (United States)

    Wan, Gengping; Luo, Yongming; Wu, Lihong; Wang, Guizhen

    2018-03-01

    CoFe/C core-shell structured nanocomposites (CoFe@C) have been fabricated through the thermal decomposition of acetylene with CoFe2O4 as precursor. The as-prepared CoFe@C was characterized by X-ray powder diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, transmission electron microscopy, and thermogravimetric analysis. The results demonstrate that the carbon shell in CoFe@C has a poor crystallization with a thickness about 5-30 nm and a content approximately 48.5 wt.%. Due to a good combination between intrinsic magnetic properties and high-electrical conductivity, the CoFe@C exhibits not only excellent absorption intensity but also wide frequency bandwidth. The minimum RL value of CoFe@C can reach - 44 dB at a thickness of 4.0 mm, and RL values below - 10 dB is up to 4.3 GHz at a thickness of 2.5 mm. The present CoFe@C may be a potential candidate for microwave absorption application.

  7. Intrinsic hierarchical structural imperfections in a natural ceramic of bivalve shell with distinctly graded properties.

    Science.gov (United States)

    Jiao, Da; Liu, Zengqian; Zhang, Zhenjun; Zhang, Zhefeng

    2015-07-22

    Despite the extensive investigation on the structure of natural biological materials, insufficient attention has been paid to the structural imperfections by which the mechanical properties of synthetic materials are dominated. In this study, the structure of bivalve Saxidomus purpuratus shell has been systematically characterized quantitatively on multiple length scales from millimeter to sub-nanometer. It is revealed that hierarchical imperfections are intrinsically involved in the crossed-lamellar structure of the shell despite its periodically packed platelets. In particular, various favorable characters which are always pursued in synthetic materials, e.g. nanotwins and low-angle misorientations, have been incorporated herein. The possible contributions of these imperfections to mechanical properties are further discussed. It is suggested that the imperfections may serve as structural adaptations, rather than detrimental defects in the real sense, to help improve the mechanical properties of natural biological materials. This study may aid in understanding the optimizing strategies of structure and properties designed by nature, and accordingly, provide inspiration for the design of synthetic materials.

  8. Structural and electrical properties of TiO2/ZnO core–shell nanoparticles synthesized by hydrothermal method

    International Nuclear Information System (INIS)

    Vlazan, P.; Ursu, D.H.; Irina-Moisescu, C.; Miron, I.; Sfirloaga, P.; Rusu, E.

    2015-01-01

    TiO 2 /ZnO core–shell nanoparticles were successfully synthesized by hydrothermal method in two stages: first stage is the hydrothermal synthesis of ZnO nanoparticles and second stage the obtained ZnO nanoparticles are encapsulated in TiO 2 . The obtained ZnO, TiO 2 and TiO 2 /ZnO core–shell nanoparticles were investigated by means of X-ray diffraction, transmission electron microscopy, Brunauer, Emmett, Teller and resistance measurements. X-ray diffraction analysis revealed the presence of both, TiO 2 and ZnO phases in TiO 2 /ZnO core–shell nanoparticles. According to transmission electron microscopy images, ZnO nanoparticles have hexagonal shapes, TiO 2 nanoparticles have a spherical shape, and TiO 2 /ZnO core–shell nanoparticles present agglomerates and the shape of particles is not well defined. The activation energy of TiO 2 /ZnO core–shell nanoparticles was about 101 meV. - Graphical abstract: Display Omitted - Highlights: • TiO 2 /ZnO core–shell nanoparticles were synthesized by hydrothermal method. • TiO 2 /ZnO core–shell nanoparticles were investigated by means of XRD, TEM and BET. • Electrical properties of TiO 2 /ZnO core–shell nanoparticles were investigated. • The activation energy of TiO 2 /ZnO core–shell nanoparticles was about E a = 101 meV

  9. Effect of laser radiation on multi-wall carbon nanotubes: study of shell structure and immobilization process

    Energy Technology Data Exchange (ETDEWEB)

    Gyoergy, Enikoe, E-mail: egyorgy@icmab.es; Perez del Pino, Angel [Instituto de Ciencia de Materiales de Barcelona, Consejo Superior de Investigaciones Cientificas (ICMAB-CSIC) (Spain); Roqueta, Jaume; Ballesteros, Belen [Centro de Investigaciones en Nanociencia y Nanotecnologia, Consejo Superior de Investigaciones Cientificas (CIN2-CSIC) (Spain); Cabana, Laura; Tobias, Gerard [Instituto de Ciencia de Materiales de Barcelona, Consejo Superior de Investigaciones Cientificas (ICMAB-CSIC) (Spain)

    2013-08-15

    Multi-wall carbon nanotubes (MWCNTs) with diameters between 10 and 15 nm were transferred and immobilized onto SiO{sub 2} glass substrates by ultraviolet matrix assisted pulsed laser evaporation (UV-MAPLE). Toluene was chosen as solvent material for the preparation of the composite MAPLE targets. An UV KrF* ({lambda} = 248 nm, {tau}{sub FWHM} {approx_equal} 25 ns, {nu} = 10 Hz) excimer laser source was used for the irradiation experiments. The effects of incident laser fluence on the structure of the laser transferred MWCNTs was investigated by high resolution transmission electron microscopy and Raman spectroscopy. The surface morphology of the laser processed MWCNTs was investigated by field emission scanning electron microscopy and atomic force microscopy in acoustic (dynamic) configuration. Network-like structures constituted by individual nanotubes and nanotube bundles were created onto solid substrates. Changes in the nanotubes' shell structure can be induced through the tuning of the laser fluence value incident onto the composite MAPLE targets.

  10. Electronic structure and mechanical properties of plasma nitrided ferrous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Portolan, E. [Centro de Ciencias Exatas e Tecnologia, Universidade de Caxias do Sul, 95070-560 Caxias do Sul-RS (Brazil); Baumvol, I.J.R. [Centro de Ciencias Exatas e Tecnologia, Universidade de Caxias do Sul, 95070-560 Caxias do Sul-RS (Brazil); Instituto de Fisica, Universidade Federal do Rio Grande do Sul, Porto Alegre 91509-970 (Brazil); Figueroa, C.A., E-mail: cafiguer@ucs.br [Centro de Ciencias Exatas e Tecnologia, Universidade de Caxias do Sul, 95070-560 Caxias do Sul-RS (Brazil)

    2009-04-15

    The electronic structures of the near-surface regions of two different nitrided steels (AISI 316 and 4140) were investigated using X-ray photoelectron spectroscopy. Photoelectron groups from all main chemical elements involved were addressed for steel samples with implanted-N concentrations in the range 16-32 at.%. As the implanted-N concentrations were increased, rather contrasting behaviors were observed for the two kinds of steel. The N1s photoelectrons had spectral shifts toward lower (nitrided AISI 316) or higher (nitrided AISI 4140) binding energies, whereas the Fe2p{sub 3/2} photoelectron spectrum remains at a constant binding energy (nitrided AISI 316) or shifts toward higher binding energies (AISI 4140). These trends are discussed in terms of the metallic nitride formation and the overlapping of atomic orbitals. For nitrided AISI 316, a semi-classical approach of charge transfer between Cr and N is used to explain the experimental facts (formation of CrN), while for nitrided AISI 4140 we propose that the interaction between orbitals 4s from Fe and 2p from N promotes electrons to the conduction band increasing the electrical attraction of the N1s and Fe2p electrons in core shells (formation of FeN{sub x}). The increase in hardness of the steel upon N implantation is attributed to the localization of electrons in specific bonds, which diminishes the metallic bond character.

  11. Electronic structure and mechanical properties of plasma nitrided ferrous alloys

    Science.gov (United States)

    Portolan, E.; Baumvol, I. J. R.; Figueroa, C. A.

    2009-04-01

    The electronic structures of the near-surface regions of two different nitrided steels (AISI 316 and 4140) were investigated using X-ray photoelectron spectroscopy. Photoelectron groups from all main chemical elements involved were addressed for steel samples with implanted-N concentrations in the range 16-32 at.%. As the implanted-N concentrations were increased, rather contrasting behaviors were observed for the two kinds of steel. The N1s photoelectrons had spectral shifts toward lower (nitrided AISI 316) or higher (nitrided AISI 4140) binding energies, whereas the Fe2p 3/2 photoelectron spectrum remains at a constant binding energy (nitrided AISI 316) or shifts toward higher binding energies (AISI 4140). These trends are discussed in terms of the metallic nitride formation and the overlapping of atomic orbitals. For nitrided AISI 316, a semi-classical approach of charge transfer between Cr and N is used to explain the experimental facts (formation of CrN), while for nitrided AISI 4140 we propose that the interaction between orbitals 4s from Fe and 2p from N promotes electrons to the conduction band increasing the electrical attraction of the N1s and Fe2p electrons in core shells (formation of FeN x). The increase in hardness of the steel upon N implantation is attributed to the localization of electrons in specific bonds, which diminishes the metallic bond character.

  12. Electronic structure and mechanical properties of plasma nitrided ferrous alloys

    International Nuclear Information System (INIS)

    Portolan, E.; Baumvol, I.J.R.; Figueroa, C.A.

    2009-01-01

    The electronic structures of the near-surface regions of two different nitrided steels (AISI 316 and 4140) were investigated using X-ray photoelectron spectroscopy. Photoelectron groups from all main chemical elements involved were addressed for steel samples with implanted-N concentrations in the range 16-32 at.%. As the implanted-N concentrations were increased, rather contrasting behaviors were observed for the two kinds of steel. The N1s photoelectrons had spectral shifts toward lower (nitrided AISI 316) or higher (nitrided AISI 4140) binding energies, whereas the Fe2p 3/2 photoelectron spectrum remains at a constant binding energy (nitrided AISI 316) or shifts toward higher binding energies (AISI 4140). These trends are discussed in terms of the metallic nitride formation and the overlapping of atomic orbitals. For nitrided AISI 316, a semi-classical approach of charge transfer between Cr and N is used to explain the experimental facts (formation of CrN), while for nitrided AISI 4140 we propose that the interaction between orbitals 4s from Fe and 2p from N promotes electrons to the conduction band increasing the electrical attraction of the N1s and Fe2p electrons in core shells (formation of FeN x ). The increase in hardness of the steel upon N implantation is attributed to the localization of electrons in specific bonds, which diminishes the metallic bond character.

  13. Electron conductance in curved quantum structures

    DEFF Research Database (Denmark)

    Willatzen, Morten; Gravesen, Jens

    2010-01-01

    is computationally fast and provides direct (geometrical) parameter insight as regards the determination of the electron transmission coefficient. We present, as a case study, calculations of the electron conductivity of a helically shaped quantum-wire structure and discuss the influence of the quantum......A differential-geometry analysis is employed to investigate the transmission of electrons through a curved quantum-wire structure. Although the problem is a three-dimensional spatial problem, the Schrodinger equation can be separated into three general coordinates. Hence, the proposed method...

  14. Core-shell structure of Miglyol/poly(D,L-lactide)/Poloxamer nanocapsules studied by small-angle neutron scattering.

    Science.gov (United States)

    Rübe, Andrea; Hause, Gerd; Mäder, Karsten; Kohlbrecher, Joachim

    2005-10-03

    The contrast variation technique in small angle neutron scattering (SANS) was used to investigate the inner structure of nanocapsules on the example of poly(D,L-lactide) (PLA) nanocapsules. The determination of the PLA and Poloxamer shell thickness was the focus of this study. Highest sensitivity on the inner structure of the nanocapsules was obtained when the scattering length density of the solvent was varied between the one of the Miglyol core and the PLA shell. According to the fit data the PLA shell thickness was 9.8 nm. The z-averaged radius determined by SANS experiments correlated well with dynamic light scattering (DLS) results, although DLS values were systematically slightly higher than the ones measured by SANS. This could be explained by taking into account the influence of Poloxamer attached to the nanocapsules surface. For a refined fit model with a second shell consisting of Poloxamer, SANS values and DLS values fitted well with each other. The characterization method presented here is significant because detailed insights into the nanocapsule and the Poloxamer shell were gained for the first time. This method could be used to develop strategies for the optimization of the shell properties concerning controlled release and to study changes in the shell structure during degradation processes.

  15. Probing the structure of CuInS{sub 2}-ZnS core-shell and similar nanocrystals by Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Dzhagan, Volodymyr, E-mail: dzhagan@isp.kiev.ua [Semiconductor Physics, Technische Universität Chemnitz, 09107 Chemnitz (Germany); V. E. Lashkaryov Institute of Semiconductors Physics, National Academy of Sciences of Ukraine, Kyiv 03028 (Ukraine); Kempken, Björn [Energy and Semiconductor Research Laboratory, Department of Physics, Carl von Ossietzky University of Oldenburg, 26111 Oldenburg (Germany); Valakh, Mykhailo [V. E. Lashkaryov Institute of Semiconductors Physics, National Academy of Sciences of Ukraine, Kyiv 03028 (Ukraine); Parisi, Jürgen; Kolny-Olesiak, Joanna [Energy and Semiconductor Research Laboratory, Department of Physics, Carl von Ossietzky University of Oldenburg, 26111 Oldenburg (Germany); Zahn, Dietrich R.T. [Semiconductor Physics, Technische Universität Chemnitz, 09107 Chemnitz (Germany)

    2017-02-15

    CuInS{sub 2}/ZnS core-shell and alloyed nanocrystals (NCs) are promising candidates for applications in biolabeling, photocatalysis, solar energy conversion, and light emitting diodes. The growth mechanism and subsequent internal structure of such heterogeneous NCs are therefore of crucial importance, as it strongly affects their optical and electronic properties. Here, we investigated using resonant Raman spectroscopy the structure of CuInS{sub 2}/ZnS and Cu-Zn-In-S/ZnS core-shell NCs, as well as the evolution of Cu{sub 2−x}S NCs into CuInS{sub 2}via the heterogeneous Cu{sub 2−x}S/CuInS{sub 2} phase. We demonstrate that the particular phases can be distinguished based on their characteristic Raman modes and tuning the exciting laser energy into resonance with the bandgap of the particular phase.

  16. Isostructural solid-solid phase transition in monolayers of soft core-shell particles at fluid interfaces: structure and mechanics.

    Science.gov (United States)

    Rey, Marcel; Fernández-Rodríguez, Miguel Ángel; Steinacher, Mathias; Scheidegger, Laura; Geisel, Karen; Richtering, Walter; Squires, Todd M; Isa, Lucio

    2016-04-21

    We have studied the complete two-dimensional phase diagram of a core-shell microgel-laden fluid interface by synchronizing its compression with the deposition of the interfacial monolayer. Applying a new protocol, different positions on the substrate correspond to different values of the monolayer surface pressure and specific area. Analyzing the microstructure of the deposited monolayers, we discovered an isostructural solid-solid phase transition between two crystalline phases with the same hexagonal symmetry, but with two different lattice constants. The two phases corresponded to shell-shell and core-core inter-particle contacts, respectively; with increasing surface pressure the former mechanically failed enabling the particle cores to come into contact. In the phase-transition region, clusters of particles in core-core contacts nucleate, melting the surrounding shell-shell crystal, until the whole monolayer moves into the second phase. We furthermore measured the interfacial rheology of the monolayers as a function of the surface pressure using an interfacial microdisk rheometer. The interfaces always showed a strong elastic response, with a dip in the shear elastic modulus in correspondence with the melting of the shell-shell phase, followed by a steep increase upon the formation of a percolating network of the core-core contacts. These results demonstrate that the core-shell nature of the particles leads to a rich mechanical and structural behavior that can be externally tuned by compressing the interface, indicating new routes for applications, e.g. in surface patterning or emulsion stabilization.

  17. Coulomb interaction in atomic and nuclear physics: Inner-Shell excitation, Coulomb dissociation of nuclei, and nuclear polarizability in electronic atoms

    International Nuclear Information System (INIS)

    Hoffmann, B.

    1984-07-01

    In three chapters different physical situations are described which have commonly the Coulomb interaction as driving force. The first two chapters study the Coulomb interactions in connection with the excitation of inner electron shells and the Coulomb excitation of nuclei in first order. In the third part on effect ofthe Coulomb interaction between electronic shell and nucleus is treated in second order (nuclear polarization), and its effect on the isotopic and isomeric shift is studied. (orig./HSI) [de

  18. Wrinkling of Pressurized Elastic Shells

    KAUST Repository

    Vella, Dominic; Ajdari, Amin; Vaziri, Ashkan; Boudaoud, Arezki

    2011-01-01

    We study the formation of localized structures formed by the point loading of an internally pressurized elastic shell. While unpressurized shells (such as a ping-pong ball) buckle into polygonal structures, we show that pressurized shells

  19. Overview of nuclear structure with electrons

    International Nuclear Information System (INIS)

    Geesaman, D. F.

    1999-01-01

    Following a broad summary of the author's view of nuclear structure in 1974, he will discuss the key elements they have learned in the past 25 years from the research at the M.I.T. Bates Linear Accelerator center and its sister electron accelerator laboratories. Electron scattering has provided the essential measurements for most of the progress. The future is bright for nuclear structure research as their ability to realistically calculate nuclear structure observables has dramatically advanced and they are increasingly able to incorporate an understanding of quantum chromodynamics into their picture of the nucleus

  20. The measurement of electrostatic potentials in core/shell GaN nanowires using off-axis electron holography

    DEFF Research Database (Denmark)

    Yazdi, Sadegh; Kasama, Takeshi; Ciechonski, R

    2013-01-01

    Core-shell GaN nanowires are expected to be building blocks of future light emitting devices. Here we apply off-axis electron holography to map the electrostatic potential distributions in such nanowires. To access the cross-section of selected individual nanowires, focused ion beam (FIB) milling...... is used. Furthermore, to assess the influence of FIB damage, the dopant potential measured from an intact NW is compared with a FIB prepared one. It is shown that in addition to the built-in potential between the p-type shell and unintentionally n-type under-layer there is a potential barrier between...... the core and under-layer which are both unintentionally n-type doped....

  1. Degenerated shell element for geometrically nonlinear analysis of thin-walled piezoelectric active structures

    International Nuclear Information System (INIS)

    Marinković, D; Köppe, H; Gabbert, U

    2008-01-01

    Active piezoelectric thin-walled structures, especially those with a notably higher membrane than bending stiffness, are susceptible to large rotations and transverse deflections. Recent investigations conducted by a number of researchers have shown that the predicted behavior of piezoelectric structures can be significantly influenced by the assumption of large displacements and rotations of the structure, thus demanding a geometrically nonlinear formulation in order to investigate it. This paper offers a degenerated shell element and a simplified formulation that relies on small incremental steps for the geometrically nonlinear analysis of piezoelectric composite structures. A set of purely mechanical static cases is followed by a set of piezoelectric coupled static cases, both demonstrating the applicability of the proposed formulation

  2. Analysis of intelligent hinged shell structures: deployable deformation and shape memory effect

    Science.gov (United States)

    Shi, Guang-Hui; Yang, Qing-Sheng; He, X. Q.

    2013-12-01

    Shape memory polymers (SMPs) are a class of intelligent materials with the ability to recover their initial shape from a temporarily fixable state when subjected to external stimuli. In this work, the thermo-mechanical behavior of a deployable SMP-based hinged structure is modeled by the finite element method using a 3D constitutive model with shape memory effect. The influences of hinge structure parameters on the nonlinear loading process are investigated. The total shape memory of the processes the hinged structure goes through, including loading at high temperature, decreasing temperature with load carrying, unloading at low temperature and recovering the initial shape with increasing temperature, are illustrated. Numerical results show that the present constitutive theory and the finite element method can effectively predict the complicated thermo-mechanical deformation behavior and shape memory effect of SMP-based hinged shell structures.

  3. Analysis of intelligent hinged shell structures: deployable deformation and shape memory effect

    International Nuclear Information System (INIS)

    Shi, Guang-Hui; Yang, Qing-Sheng; He, X Q

    2013-01-01

    Shape memory polymers (SMPs) are a class of intelligent materials with the ability to recover their initial shape from a temporarily fixable state when subjected to external stimuli. In this work, the thermo-mechanical behavior of a deployable SMP-based hinged structure is modeled by the finite element method using a 3D constitutive model with shape memory effect. The influences of hinge structure parameters on the nonlinear loading process are investigated. The total shape memory of the processes the hinged structure goes through, including loading at high temperature, decreasing temperature with load carrying, unloading at low temperature and recovering the initial shape with increasing temperature, are illustrated. Numerical results show that the present constitutive theory and the finite element method can effectively predict the complicated thermo-mechanical deformation behavior and shape memory effect of SMP-based hinged shell structures. (paper)

  4. Hysteresis and compensation behaviors of mixed spin-2 and spin-1 hexagonal Ising nanowire core–shell structure

    Energy Technology Data Exchange (ETDEWEB)

    Masrour, R., E-mail: rachidmasrour@hotmail.com [Laboratory of Materials, Processes, Environment and Quality, Cady Ayyed University, National School of Applied Sciences, 63 46000 Safi (Morocco); Laboratoire de Magnétisme et Physique des Hautes Energies L.M.P.H.E.URAC 12, Université Mohammed V, Faculté des Sciences, B.P. 1014 Rabat (Morocco); Jabar, A. [Laboratoire de Magnétisme et Physique des Hautes Energies L.M.P.H.E.URAC 12, Université Mohammed V, Faculté des Sciences, B.P. 1014 Rabat (Morocco); Benyoussef, A. [Laboratoire de Magnétisme et Physique des Hautes Energies L.M.P.H.E.URAC 12, Université Mohammed V, Faculté des Sciences, B.P. 1014 Rabat (Morocco); Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Hassan II Academy of Science and Technology, Rabat (Morocco); Hamedoun, M. [Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Bahmad, L. [Laboratoire de Magnétisme et Physique des Hautes Energies L.M.P.H.E.URAC 12, Université Mohammed V, Faculté des Sciences, B.P. 1014 Rabat (Morocco)

    2015-09-01

    The magnetic behaviors of a mixed spins (2-1) hexagonal Ising nanowire with core–shell structure are investigated by using the Monte Carlo simulations. The thermal magnetizations, the magnetic susceptibilities and the transition temperatures of core–shell are studied for different values of crystal field and exchange interactions. The thermal and magnetic hysteresis cycles are given for different values of the crystal field. - Highlights: • Critical temperature increase when exchange interaction increasing in core-shell. • Hysteresis loop areas decrease at above transition temperature. • Magnetic coercive field decrease when crystal field increasing. • Magnetic coercive field increase when exchange interaction increasing.

  5. The effect of magnetic field and donor impurity on electron spectrum in spherical core-shell quantum dot

    Science.gov (United States)

    Holovatsky, V. A.; Voitsekhivska, O. M.; Yakhnevych, M. Ya

    2018-04-01

    The effect of homogeneous magnetic field and location of donor impurity on the electron energy spectrum and distribution of its probability density in spherical core-shell quantum dot is investigated. In the framework of the effective mass approximation and rectangular infinitely deep potential well, the solutions of the Schrodinger equation are found using the matrix method. The wave functions are expanded over the complete set of exact functions obtained without the magnetic field and impurity. It is shown that when the induction of magnetic field increases, the ground state of electron in the nanostructure without impurity or on-center impurity is successively formed by the states with m = 0, -1, -2, … (Aharonov-Bohm effect). When donor impurity is located in the shell of the nanostructure the Aharonov-Bohm effect vanishes. The dependences of electron energy spectrum and its wave functions on the location of impurity, placed along the direction of magnetic field or perpendicularly to it, are studied. It is shown, that in the first case, the quantum states are characterized by the certain value of magnetic quantum number m and the expansion contains the wave functions of the states with it only. In the second case, the cylindrical symmetry of the problem is broken and the new quantum states are formed from the states with different values of all three quantum numbers n, l, m and electron energy spectrum weakly depends on the magnetic field induction.

  6. Structural-performance testing of titanium-shell lead-matrix container MM2

    Energy Technology Data Exchange (ETDEWEB)

    Hosaluk, L. J.; Barrie, J. N.

    1992-05-15

    This report describes the hydrostatic structural-performance testing of a half-scale, titanium-shell, lead-matrix container (MM2) with a large, simulated volumetric casting defect. Mechancial behaviour of the container is assessed from extensive surface-strain measurements and post-test non-destructive and destructive examinations. Measured strain data are compared briefly with analytical results from a finite-element model of a previous test prototype, MM1, and with data generated by a finite-difference computer code. Finally, procedures are recommended for more detailed analytical modelling. (auth)

  7. Vibration test of spherical shell structure and replacing method into mathematical model

    International Nuclear Information System (INIS)

    Takayanagi, M.; Suzuki, S.; Okamura, T.; Haas, E.E.; Krutzik, N.J.

    1989-01-01

    To verify the beam-type and oval-type vibratory characteristics of a spherical shell structure, two test specimens were made and vibration tests were carried out. Results of these tests are compared with results of detailed analyses using 3-D FEM and 2-D axisymmetric FEM models. The analytical results of overall vibratory characteristics are in good agreement with the test results, has been found that the effect of the attached mass should be considered in evaluating local vibration. The replacing method into equivalent beam model is proposed

  8. Shell supports

    DEFF Research Database (Denmark)

    Almegaard, Henrik

    2004-01-01

    A new statical and conceptual model for membrane shell structures - the stringer system - has been found. The principle was first published at the IASS conference in Copenhagen (OHL91), and later the theory has been further developed (ALMO3)(ALMO4). From the analysis of the stringer model it can...... be concluded that all membrane shells can be described by a limited number of basic configurations of which quite a few have free edges....

  9. Yolk-shell structured Sb@C anodes for high energy Na-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Song, Junhua; Yan, Pengfei; Luo, Langli; Qi, Xingguo; Rong, Xiaohui; Zheng, Jianming; Xiao, Biwei; Feng, Shuo; Wang, Chongmin; Hu, Yong-Sheng; Lin, Yuehe; Sprenkle, Vincent L.; Li, Xiaolin

    2017-10-01

    Despite great advances in sodium-ion battery developments, the search for high energy and stable anode materials remains a challenge. Alloy or conversion-typed anode materials are attractive candidates of high specific capacity and low voltage potential, yet their applications are hampered by the large volume expansion and hence poor electrochemical reversibility and fast capacity fade. Here, we use antimony (Sb) as an example to demonstrate the use of yolk-shell structured anodes for high energy Na-ion batteries. The Sb@C yolk-shell structure prepared by controlled reduction and selective removal of Sb2O3 from carbon coated Sb2O3 nanoparticles can accommodate the Sb swelling upon sodiation and improve the structural/electrical integrity against pulverization. It delivers a high specific capacity of ~554 mAh•g-1, good rate capability (315 mhA•g-1 at 10C rate) and long cyclability (92% capacity retention over 200 cycles). Full-cells of O3-Na0.9[Cu0.22Fe0.30Mn0.48]O2 cathodes and Sb@C-hard carbon composite anodes demonstrate a high specific energy of ~130 Wh•kg-1 (based on the total mass of cathode and anode) in the voltage range of 2.0-4.0 V, ~1.5 times energy of full-cells with similar design using hard carbon anodes.

  10. Subscale and Full-Scale Testing of Buckling-Critical Launch Vehicle Shell Structures

    Science.gov (United States)

    Hilburger, Mark W.; Haynie, Waddy T.; Lovejoy, Andrew E.; Roberts, Michael G.; Norris, Jeffery P.; Waters, W. Allen; Herring, Helen M.

    2012-01-01

    New analysis-based shell buckling design factors (aka knockdown factors), along with associated design and analysis technologies, are being developed by NASA for the design of launch vehicle structures. Preliminary design studies indicate that implementation of these new knockdown factors can enable significant reductions in mass and mass-growth in these vehicles and can help mitigate some of NASA s launch vehicle development and performance risks by reducing the reliance on testing, providing high-fidelity estimates of structural performance, reliability, robustness, and enable increased payload capability. However, in order to validate any new analysis-based design data or methods, a series of carefully designed and executed structural tests are required at both the subscale and full-scale level. This paper describes recent buckling test efforts at NASA on two different orthogrid-stiffened metallic cylindrical shell test articles. One of the test articles was an 8-ft-diameter orthogrid-stiffened cylinder and was subjected to an axial compression load. The second test article was a 27.5-ft-diameter Space Shuttle External Tank-derived cylinder and was subjected to combined internal pressure and axial compression.

  11. Electronic Structure of Eu6C60

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-Xiong; LI Hong-Nian; XU Ya-Bo; WANG Peng; ZHANG Wen-Hua; XU Fa-Qiang

    2009-01-01

    We study the valence band of Eu-intercalated C60 by synchrotron radiation photoelectron spectroscopy to un-derstand the ferromagnetism (FM) and the giant magnetoresistance (GMR) of Eu6C60. The results reveal the semiconducting property and the remarkable 5d6s-π hybridization. Eu-C60 bonding has both ionic and covalent contributions. No more than half the 5d6s electrons transfer from Eu to the LUMO derived band of C60, and the LUMO+1 derived band is not filled. The remaining valence electrons of Eu, together with some π (LUMO, HOMO and HOMO-1) electrons, constitute the covalent bond. The electronic structure implies that the magnetic coupling in Eu6C60 should be through the intra-atomic f-sd exchange and the medium of the π electrons. The possibility of the GMR being tunnelling magnetoresistance is ruled out.

  12. Electron mobility limited by optical phonons in wurtzite InGaN/GaN core-shell nanowires

    Science.gov (United States)

    Liu, W. H.; Qu, Y.; Ban, S. L.

    2017-09-01

    Based on the force-balance and energy-balance equations, the optical phonon-limited electron mobility in InxGa1-xN/GaN core-shell nanowires (CSNWs) is discussed. It is found that the electrons tend to distribute in the core of the CSNWs due to the strong quantum confinement. Thus, the scattering from first kind of the quasi-confined optical (CO) phonons is more important than that from the interface (IF) and propagating (PR) optical phonons. Ternary mixed crystal and size effects on the electron mobility are also investigated. The results show that the PR phonons exist while the IF phonons disappear when the indium composition x < 0.047, and vice versa. Accordingly, the total electron mobility μ first increases and then decreases with indium composition x, and reaches a peak value of approximately 3700 cm2/(V.s) when x = 0.047. The results also show that the mobility μ increases as increasing the core radius of CSNWs due to the weakened interaction between the electrons and CO phonons. The total electron mobility limited by the optical phonons exhibits an obvious enhancement as decreasing temperature or increasing line electron density. Our theoretical results are expected to be helpful to develop electronic devices based on CSNWs.

  13. Influence of core size on the upconversion luminescence properties of spherical Gd2O3:Yb3+/Er3+@SiO2 particles with core-shell structures

    International Nuclear Information System (INIS)

    Zheng, Kezhi; Liu, Zhenyu; Liu, Ye; Song, Weiye; Qin, Weiping

    2013-01-01

    Spherical SiO 2 particles with different sizes (30, 80, 120, and 180 nm) have been coated with Gd 2 O 3 :Yb 3+ /Er 3+ layers by a heterogeneous precipitation method, leading to the formation of core-shell structural Gd 2 O 3 :Yb 3+ /Er 3+ @SiO 2 particles. The samples were characterized by using X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, upconversion (UC) emission spectra, and fluorescent dynamical analysis. The obtained core-shell particles have perfect spherical shape with narrow size distribution. Under the excitation of 980 nm diode laser, the core-shell samples showed size-dependent upconversion luminescence (UCL) properties. The inner SiO 2 cores in core-shell samples were proved to have limited effect on the total UCL intensities of Er 3+ ions. The UCL intensities of core-shell particles were demonstrated much higher than the values obtained in pure Gd 2 O 3 :Yb 3+ /Er 3+ with the same phosphor volume. The dependence of the specific area of a UCL shell on the size of its inner SiO 2 particle was calculated and analyzed for the first time. It was confirmed that the surface effect came from the outer surfaces of emitting shells is dominant in influencing the UCL property in the core-shell samples. Three-photon UC processes for the green emissions were observed in the samples with small sizes of SiO 2 cores. The results of dynamical analysis illustrated that more nonradiative relaxation occurred in the core-shell samples with smaller SiO 2 core sizes

  14. Largely improved the low temperature toughness of acrylonitrile-styrene-acrylate (ASA) resin: Fabricated a core-shell structure of two elastomers through the differences of interfacial tensions

    Science.gov (United States)

    Mao, Zepeng; Zhang, Jun

    2018-06-01

    The phase morphology of two elastomers (i.e., chlorinated polyethylene (CPE) and polybutadiene rubber (BR)) were devised to be a core-shell structure in acrylonitrile-styrene-acrylate (ASA) resin matrix, via the interfacial tension differences of polymer pairs. Selective extraction test and scanning electron microscopy (SEM) were utilized to verify this special phase morphology. The results demonstrated that the core-shell structure, BR core and CPE shell, significantly contributed to improve the low temperature toughness of ASA/CPE/BR ternary blends, which may be because the nonpolar BR core was segregated from polar ASA by the CPE shell. The CPE shell served dual functions: Not only did it play compatibilizing effect in the interface between BR and ASA matrix, but it also toughened the blends at 25 and 0 °C. The blends of ASA/CPE/BR (100/27/3, w/w/w) and ASA/CPE/BR (100/22/8, w/w/w) showed the peak impact strengths at about 28 and 9 kJ/m2 at 0 and -30 °C, respectively, which were higher than both that of ASA/CPE/BR (100/30/0, w/w/w) and ASA/CPE/BR (100/0/30, w/w/w). Moreover, the impact strength of ternary blends at room temperature kept at 40 kJ/m2 when BR content was lower than 10 phr. Other characterizations including contact angle measurement, dynamic mechanical thermal analysis (DMTA), morphology of impact-fractured surfaces, tensile properties, flexural properties, and Fourier transform infrared spectroscopy (FTIR) were measured as well.

  15. Atomic and electronic structures of novel silicon surface structures

    Energy Technology Data Exchange (ETDEWEB)

    Terry, J.H. Jr.

    1997-03-01

    The modification of silicon surfaces is presently of great interest to the semiconductor device community. Three distinct areas are the subject of inquiry: first, modification of the silicon electronic structure; second, passivation of the silicon surface; and third, functionalization of the silicon surface. It is believed that surface modification of these types will lead to useful electronic devices by pairing these modified surfaces with traditional silicon device technology. Therefore, silicon wafers with modified electronic structure (light-emitting porous silicon), passivated surfaces (H-Si(111), Cl-Si(111), Alkyl-Si(111)), and functionalized surfaces (Alkyl-Si(111)) have been studied in order to determine the fundamental properties of surface geometry and electronic structure using synchrotron radiation-based techniques.

  16. Seniority structure of the cranked shell model wave function and the pairing phase transition

    International Nuclear Information System (INIS)

    Wu, C.S.; Zeng, J.Y.; Center of Theoretical Physics, China Center of Advanced Science and Technology

    1989-01-01

    The accurate solutions to the low-lying eigenstates of the cranked shell model Hamiltonian are obtained by the particle-number-conserving treatment, in which a many-particle configuration truncation is adopted instead of the conventional single-particle level truncation. The variation of the seniority structures of low-lying eigenstates with rotational frequency ω is analyzed. The gap parameter of the yrast band decreases with ω very slowly, though the seniority structure has undergone a great change. It is suggested to use the seniority structure to indicate the possible pairing phase transition from a superconducting state to a normal state. The important blocking effects on the low-lying eigenstates are discussed

  17. Electronic Band Structure of BaCo_{2}As_{2}: A Fully Doped Ferropnictide Analog with Reduced Electronic Correlations

    Directory of Open Access Journals (Sweden)

    N. Xu

    2013-01-01

    Full Text Available We report an investigation with angle-resolved photoemission spectroscopy of the Fermi surface and electronic band structure of BaCo_{2}As_{2}. Although its quasinesting-free Fermi surface differs drastically from that of its Fe-pnictide cousins, we show that the BaCo_{2}As_{2} system can be used as an approximation to the bare unoccupied band structure of the related BaFe_{2-x}Co_{x}As_{2} and Ba_{1-x}K_{x}Fe_{2}As_{2} compounds. However, our experimental results, in agreement with dynamical-mean-field-theory calculations, indicate that electronic correlations are much less important in BaCo_{2}As_{2} than in the ferropnictides. Our findings suggest that this effect is due to the increased filling of the electronic 3d shell in the presence of significant Hund’s exchange coupling.

  18. Facile fabrication of core–shell ZnO/Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} nanorods: Enhanced photoluminescence through electron charge

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Shengfei; Gao, Hongli [School of Materials Science & Engineering, Beihang University, Beijing 100191 (China); Deng, Yuan, E-mail: dengyuan@buaa.edu.cn [School of Materials Science & Engineering, Beihang University, Beijing 100191 (China); Wang, Yao [School of Materials Science & Engineering, Beihang University, Beijing 100191 (China); Qu, Shengchun, E-mail: qsc@semi.ac.cn [Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China)

    2016-01-15

    Graphical abstract: - Highlights: • The Bi{sub 0.5}Sb{sub 1.5}Te{sub 3}/ZnO core–shells prepared by combining a facile hydrothermal growth and magnetron sputtering approach. • The light absorption and photoluminescence emission of the ZnO and the Bi{sub 0.5}Sb{sub 1.5}Te{sub 3}/ZnO core–shells are investigated. • The core–shell structure reveals a simultaneous novelty enhancement of the photoluminescence emission in the UV and visible range. • The mechanism for the PL simultaneous enhancement is described. - Abstract: Surface decoration techniques are emerging as promising strategy to improve the optical properties of the ZnO based materials. The core–shell ZnO/Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} nanorods were grown on a FTO substrate through a facile hydrothermal and magnetron sputtering combined approach. The microstructure of the core–shell nanorod arrays were investigated by the X-ray diffraction (XRD), a field emission Scanning electron microscopy (SEM) and high resolution transmission electron microscope (HTEM). The optical properties of the core–shell nanorod arrays were investigated through the diffuse reflectance absorption spectra and photoluminescence emission. The visible light absorption and especially the photoluminescence emission of the ZnO nanorods are enhanced markedly with the Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} grains coating the ZnO nanorods through the electron charge.

  19. Structural changes induced by electron irradiation

    International Nuclear Information System (INIS)

    Koike, J.; Pedraza, D.F.

    1993-01-01

    Highly oriented pyrolytic graphite was irradiated at room temperature with 300 kV electrons. Transmission electron microscopy and electron energy loss spectroscopy were employed to study the structural changes produced by irradiation. The occurrence of a continuous ring intensity in the selected area diffraction (SAD) pattern obtained on a specimen irradiated with the electron beam parallel to the c-crystallographic axis indicated that microstructural changes had occurred. However, from the SAD pattern obtained for the specimens tilted relative to the irradiation direction, it was found that up to a fluence of 1.1x10 27 e/m 2 graphite remained crystalline. An SAD pattern of a specimen irradiated with the electron beam perpendicular to the c-axis confirmed the persistence of crystalline order. High resolution electron microscopy showed that ordering along the c-axis direction remained. A density reduction of 8.9% due to irradiation was determined from the plasmon frequency shift. A qualitative model is proposed to explain these observations. A new determination of the threshold displacement energy, Ed, of carbon atoms in graphite was done by examining the appearance of a continuous ring in the SAD pattern at various electron energies. A value of 30 eV was obtained whether the incident electron beam was parallel or perpendicular to the c-axis, demonstrating that Ed is independent of the displacement direction

  20. Structural stability and electronic structure of YCu ductile ...

    African Journals Online (AJOL)

    We investigate the structural, elastic and electronic properties of cubic YCu intermetallic compound. Which crystallize in the CsCl- B2 type structure, the investigated using the first principle full potential linearized augmented plane wave method (FP-LAPW) within density functional Theory (DFT). We used generalized ...

  1. Efficient electronic structure methods applied to metal nanoparticles

    DEFF Research Database (Denmark)

    Larsen, Ask Hjorth

    of efficient approaches to density functional theory and the application of these methods to metal nanoparticles. We describe the formalism and implementation of localized atom-centered basis sets within the projector augmented wave method. Basis sets allow for a dramatic increase in performance compared....... The basis set method is used to study the electronic effects for the contiguous range of clusters up to several hundred atoms. The s-electrons hybridize to form electronic shells consistent with the jellium model, leading to electronic magic numbers for clusters with full shells. Large electronic gaps...... and jumps in Fermi level near magic numbers can lead to alkali-like or halogen-like behaviour when main-group atoms adsorb onto gold clusters. A non-self-consistent NewnsAnderson model is used to more closely study the chemisorption of main-group atoms on magic-number Au clusters. The behaviour at magic...

  2. Crossover from disordered to core-shell structures of nano-oxide Y{sub 2}O{sub 3} dispersed particles in Fe

    Energy Technology Data Exchange (ETDEWEB)

    Higgins, M. P.; Wang, L. M.; Gao, F., E-mail: gaofeium@umich.edu [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States); Lu, C. Y. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States); Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang, Liaoning 110819 (China); Lu, Z. [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang, Liaoning 110819 (China); Shao, L. [Department of Nuclear Engineering, Texas A& M University, College Station, Texas 77843 (United States)

    2016-07-18

    Molecular dynamic simulations of Y{sub 2}O{sub 3} in bcc Fe and transmission electron microscopy (TEM) observations were used to understand the structure of Y{sub 2}O{sub 3} nano-clusters in an oxide dispersion strengthened steel matrix. The study showed that Y{sub 2}O{sub 3} nano-clusters below 2 nm were completely disordered. Y{sub 2}O{sub 3} nano-clusters above 2 nm, however, form a core-shell structure, with a shell thickness of 0.5–0.7 nm that is independent of nano-cluster size. Y{sub 2}O{sub 3} nano-clusters were surrounded by off-lattice Fe atoms, further increasing the stability of these nano-clusters. TEM was used to corroborate our simulation results and showed a crossover from a disordered nano-cluster to a core-shell structure.

  3. Adaptive resolution simulation of a biomolecule and its hydration shell: Structural and dynamical properties

    International Nuclear Information System (INIS)

    Fogarty, Aoife C.; Potestio, Raffaello; Kremer, Kurt

    2015-01-01

    A fully atomistic modelling of many biophysical and biochemical processes at biologically relevant length- and time scales is beyond our reach with current computational resources, and one approach to overcome this difficulty is the use of multiscale simulation techniques. In such simulations, when system properties necessitate a boundary between resolutions that falls within the solvent region, one can use an approach such as the Adaptive Resolution Scheme (AdResS), in which solvent particles change their resolution on the fly during the simulation. Here, we apply the existing AdResS methodology to biomolecular systems, simulating a fully atomistic protein with an atomistic hydration shell, solvated in a coarse-grained particle reservoir and heat bath. Using as a test case an aqueous solution of the regulatory protein ubiquitin, we first confirm the validity of the AdResS approach for such systems, via an examination of protein and solvent structural and dynamical properties. We then demonstrate how, in addition to providing a computational speedup, such a multiscale AdResS approach can yield otherwise inaccessible physical insights into biomolecular function. We use our methodology to show that protein structure and dynamics can still be correctly modelled using only a few shells of atomistic water molecules. We also discuss aspects of the AdResS methodology peculiar to biomolecular simulations

  4. A novel approach to preparing magnetic protein microspheres with core-shell structure

    International Nuclear Information System (INIS)

    Jiang Wei; Sun Zhendong; Li Fengsheng; Chen Kai; Liu Tianyu; Liu Jialing; Zhou Tianle; Guo Rui

    2011-01-01

    Magnetic protein microspheres with core-shell structure were prepared through a novel approach based on the sonochemical method and the emulsion solvent evaporation method. The microspheres are composed of the oleic acid and undecylenic acid modified Fe 3 O 4 cores and coated with globular bovine serum albumin (BSA). Under an optimized condition, up to 57.8 wt% of approximately 10 nm superparamagnetic Fe 3 O 4 nanoparticles could be uniformly encapsulated into the BSA microspheres with the diameter of approximately 160 nm and the high saturation magnetization of 38.5 emu/g, besides of the abundant functional groups. The possible formation mechanism of magnetic microspheres was discussed in detail. - Research Highlights: → Magnetic protein microspheres with core-shell structure were prepared through a novel approach based on the sonochemical method and the emulsion solvent evaporation method.→ The microspheres are composed of the oleic acid and undecylenic acid modified Fe 3 O 4 cores and coated with globular bovine serum albumin (BSA).→ 57.8 wt% of approximately 10 nm superparamagnetic Fe 3 O 4 nanoparticles could be uniformly encapsulated into the BSA microspheres with the diameter of approximately 160 nm and the high saturation magnetization of 38.5 emu/g, besides the abundant functional groups.

  5. A novel approach to preparing magnetic protein microspheres with core-shell structure

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Wei, E-mail: climentjw@126.co [National Special Superfine Powder Engineering Research Center, Nanjing University of Science and Technology, Nanjing 210094 (China); Sun Zhendong; Li Fengsheng [National Special Superfine Powder Engineering Research Center, Nanjing University of Science and Technology, Nanjing 210094 (China); Chen Kai; Liu Tianyu; Liu Jialing [Department of Physics, Nanjing University of Science and Technology, Nanjing 210094 (China); Zhou Tianle [Department of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Guo Rui [Department of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China)

    2011-03-15

    Magnetic protein microspheres with core-shell structure were prepared through a novel approach based on the sonochemical method and the emulsion solvent evaporation method. The microspheres are composed of the oleic acid and undecylenic acid modified Fe{sub 3}O{sub 4} cores and coated with globular bovine serum albumin (BSA). Under an optimized condition, up to 57.8 wt% of approximately 10 nm superparamagnetic Fe{sub 3}O{sub 4} nanoparticles could be uniformly encapsulated into the BSA microspheres with the diameter of approximately 160 nm and the high saturation magnetization of 38.5 emu/g, besides of the abundant functional groups. The possible formation mechanism of magnetic microspheres was discussed in detail. - Research Highlights: Magnetic protein microspheres with core-shell structure were prepared through a novel approach based on the sonochemical method and the emulsion solvent evaporation method. The microspheres are composed of the oleic acid and undecylenic acid modified Fe{sub 3}O{sub 4} cores and coated with globular bovine serum albumin (BSA). 57.8 wt% of approximately 10 nm superparamagnetic Fe{sub 3}O{sub 4} nanoparticles could be uniformly encapsulated into the BSA microspheres with the diameter of approximately 160 nm and the high saturation magnetization of 38.5 emu/g, besides the abundant functional groups.

  6. Adaptive resolution simulation of a biomolecule and its hydration shell: Structural and dynamical properties

    Energy Technology Data Exchange (ETDEWEB)

    Fogarty, Aoife C., E-mail: fogarty@mpip-mainz.mpg.de; Potestio, Raffaello, E-mail: potestio@mpip-mainz.mpg.de; Kremer, Kurt, E-mail: kremer@mpip-mainz.mpg.de [Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz (Germany)

    2015-05-21

    A fully atomistic modelling of many biophysical and biochemical processes at biologically relevant length- and time scales is beyond our reach with current computational resources, and one approach to overcome this difficulty is the use of multiscale simulation techniques. In such simulations, when system properties necessitate a boundary between resolutions that falls within the solvent region, one can use an approach such as the Adaptive Resolution Scheme (AdResS), in which solvent particles change their resolution on the fly during the simulation. Here, we apply the existing AdResS methodology to biomolecular systems, simulating a fully atomistic protein with an atomistic hydration shell, solvated in a coarse-grained particle reservoir and heat bath. Using as a test case an aqueous solution of the regulatory protein ubiquitin, we first confirm the validity of the AdResS approach for such systems, via an examination of protein and solvent structural and dynamical properties. We then demonstrate how, in addition to providing a computational speedup, such a multiscale AdResS approach can yield otherwise inaccessible physical insights into biomolecular function. We use our methodology to show that protein structure and dynamics can still be correctly modelled using only a few shells of atomistic water molecules. We also discuss aspects of the AdResS methodology peculiar to biomolecular simulations.

  7. Bio-inspired passive actuator simulating an abalone shell mechanism for structural control

    International Nuclear Information System (INIS)

    Yang, Henry T Y; Lin, Chun-Hung; Bridges, Daniel; Randall, Connor J; Hansma, Paul K

    2010-01-01

    An energy dispersion mechanism called 'sacrificial bonds and hidden length', which is found in some biological systems, such as abalone shells and bones, is the inspiration for new strategies for structural control. Sacrificial bonds and hidden length can substantially increase the stiffness and enhance energy dissipation in the constituent molecules of abalone shells and bone. Having been inspired by the usefulness and effectiveness of such a mechanism, which has evolved over millions of years and countless cycles of evolutions, the authors employ the conceptual underpinnings of this mechanism to develop a bio-inspired passive actuator. This paper presents a fundamental method for optimally designing such bio-inspired passive actuators for structural control. To optimize the bio-inspired passive actuator, a simple method utilizing the force–displacement–velocity (FDV) plots based on LQR control is proposed. A linear regression approach is adopted in this research to find the initial values of the desired parameters for the bio-inspired passive actuator. The illustrative examples, conducted by numerical simulation with experimental validation, suggest that the bio-inspired passive actuator based on sacrificial bonds and hidden length may be comparable in performance to state-of-the-art semi-active actuators

  8. Bio-inspired passive actuator simulating an abalone shell mechanism for structural control

    Science.gov (United States)

    Yang, Henry T. Y.; Lin, Chun-Hung; Bridges, Daniel; Randall, Connor J.; Hansma, Paul K.

    2010-10-01

    An energy dispersion mechanism called 'sacrificial bonds and hidden length', which is found in some biological systems, such as abalone shells and bones, is the inspiration for new strategies for structural control. Sacrificial bonds and hidden length can substantially increase the stiffness and enhance energy dissipation in the constituent molecules of abalone shells and bone. Having been inspired by the usefulness and effectiveness of such a mechanism, which has evolved over millions of years and countless cycles of evolutions, the authors employ the conceptual underpinnings of this mechanism to develop a bio-inspired passive actuator. This paper presents a fundamental method for optimally designing such bio-inspired passive actuators for structural control. To optimize the bio-inspired passive actuator, a simple method utilizing the force-displacement-velocity (FDV) plots based on LQR control is proposed. A linear regression approach is adopted in this research to find the initial values of the desired parameters for the bio-inspired passive actuator. The illustrative examples, conducted by numerical simulation with experimental validation, suggest that the bio-inspired passive actuator based on sacrificial bonds and hidden length may be comparable in performance to state-of-the-art semi-active actuators.

  9. Electron acoustic nonlinear structures in planetary magnetospheres

    Science.gov (United States)

    Shah, K. H.; Qureshi, M. N. S.; Masood, W.; Shah, H. A.

    2018-04-01

    In this paper, we have studied linear and nonlinear propagation of electron acoustic waves (EAWs) comprising cold and hot populations in which the ions form the neutralizing background. The hot electrons have been assumed to follow the generalized ( r , q ) distribution which has the advantage that it mimics most of the distribution functions observed in space plasmas. Interestingly, it has been found that unlike Maxwellian and kappa distributions, the electron acoustic waves admit not only rarefactive structures but also allow the formation of compressive solitary structures for generalized ( r , q ) distribution. It has been found that the flatness parameter r , tail parameter q , and the nonlinear propagation velocity u affect the propagation characteristics of nonlinear EAWs. Using the plasmas parameters, typically found in Saturn's magnetosphere and the Earth's auroral region, where two populations of electrons and electron acoustic solitary waves (EASWs) have been observed, we have given an estimate of the scale lengths over which these nonlinear waves are expected to form and how the size of these structures would vary with the change in the shape of the distribution function and with the change of the plasma parameters.

  10. Structure of conduction electrons on polysilanes

    Energy Technology Data Exchange (ETDEWEB)

    Ichikawa, Tsuneki [Hokkaido Univ., Sapporo (Japan); Kumagai, Jun

    1998-10-01

    The orbital structures of conduction electrons on permethylated oligosilane, Si{sub 2n}(CH{sub 3}){sub 2n+2}(n = 2 - 8), and poly(cyclohexylmethylsilane) have been determined by the electron spin-echo envelope modulation signals of the radical anions of these silanes in a deuterated rigid matrix at 77 K. The conduction electron on permethylated oligosilane is delocalized over the entire main chain, whereas that on poly(cyclohexylmethylsilane) is localized on a part of the main chain composed of about six Si atoms. Quantum-chemical calculations suggest that Anderson localization due to fluctuation of {sigma} conjugation by conformational disorder of the main chain is responsible for the localization of both the conduction electron and the hole. (author)

  11. Electronic structure of MgB2

    Indian Academy of Sciences (India)

    Abstract. Results of ab initio electronic structure calculations on the compound MgB2 using the. FPLAPW method employing GGA for the exchange-correlation energy are presented. Total energy minimization enables us to estimate the equilibrium volume, c/a ratio and the bulk modulus, all of which are in excellent ...

  12. Electronic structure of Fe-based superconductors

    Indian Academy of Sciences (India)

    Abstract. Fe-based superconductors have drawn much attention during the last decade due to the presence of superconductivity in materials containing the magnetic element, Fe, and the coexistence of superconductivity and magnetism. Extensive study of the electronic structure of these systems suggested the dominant ...

  13. Electronic structure of Fe-based superconductors

    Indian Academy of Sciences (India)

    2015-05-29

    May 29, 2015 ... Fe-based superconductors have drawn much attention during the last decade due to the presence of superconductivity in materials containing the magnetic element, Fe, and the coexistence of superconductivity and magnetism. Extensive study of the electronic structure of these systems suggested the ...

  14. Electronic structure of MgB 2

    Indian Academy of Sciences (India)

    Results of ab initio electronic structure calculations on the compound MgB2 using the FPLAPW method employing GGA for the exchange-correlation energy are presented. Total energy minimization enables us to estimate the equilibrium volume, / ratio and the bulk modulus, all of which are in excellent agreement with ...

  15. The electronic structure of antiferromagnetic chromium

    DEFF Research Database (Denmark)

    Skriver, Hans Lomholt

    1981-01-01

    The author has used the local spin density formalism to perform self-consistent calculations of the electronic structure of chromium in the non-magnetic and commensurate antiferromagnetic phases, as a function of the lattice parameter. A change of a few per cent in the atomic radius brings...

  16. Electronic structure calculations of calcium silicate hydrates

    International Nuclear Information System (INIS)

    Sterne, P.A.; Meike, A.

    1995-11-01

    Many phases in the calcium-silicate-hydrate system can develop in cement exposed over long periods of time to temperatures above 25 C. As a consequence, chemical reactions involving these phases can affect the relative humidity and water chemistry of a radioactive waste repository that contains significant amounts of cement. In order to predict and simulate these chemical reactions, the authors are developing an internally consistent database of crystalline Ca-Si-hydrate structures. The results of first principles electronic structure calculations on two such phases, wollastonite (CaSiO 3 ) and xonotlite (Ca 6 Si 6 O 17 (OH) 2 ), are reported here. The calculated ground state properties are in very good agreement with experiment, providing equilibrium lattice parameters within about 1--1.4% of the experimentally reported values. The roles of the different types of oxygen atoms, which are fundamental to understanding the energetics of crystalline Ca-Si-hydrates are briefly discussed in terms of their electronic state densities. The good agreement with experiment for the lattice parameters and the consistency of the electronic density of states features for the two structures demonstrate the applicability of these electronic structure methods in calculating the fundamental properties of these phases

  17. Optimal Sensor Placement for Latticed Shell Structure Based on an Improved Particle Swarm Optimization Algorithm

    Directory of Open Access Journals (Sweden)

    Xun Zhang

    2014-01-01

    Full Text Available Optimal sensor placement is a key issue in the structural health monitoring of large-scale structures. However, some aspects in existing approaches require improvement, such as the empirical and unreliable selection of mode and sensor numbers and time-consuming computation. A novel improved particle swarm optimization (IPSO algorithm is proposed to address these problems. The approach firstly employs the cumulative effective modal mass participation ratio to select mode number. Three strategies are then adopted to improve the PSO algorithm. Finally, the IPSO algorithm is utilized to determine the optimal sensors number and configurations. A case study of a latticed shell model is implemented to verify the feasibility of the proposed algorithm and four different PSO algorithms. The effective independence method is also taken as a contrast experiment. The comparison results show that the optimal placement schemes obtained by the PSO algorithms are valid, and the proposed IPSO algorithm has better enhancement in convergence speed and precision.

  18. Shell structure effects at high excitations and many-quasiparticle configurations

    International Nuclear Information System (INIS)

    Soloviev, V.G.

    1980-01-01

    Experimental and theoretical data available on few- and many-quasiparticle components of the wave functions of complex nuclei at low, intermediate and high energies are shortly analyzed. The components are treated in the nuclear quasiparticle-phonon model. Specific features of the lowest and high-spin states, giant resonances, neutron resonances and the effects of the energy-level structure in the few-and many-particle transfer reactions are discussed. It is concluded that the most reliable nuclear properties are determined by the components, their behaviour reflecting the shell structure effects. Wich increasing excitation energy the density of levels increases exponentially and the contribution of few-quasiparticle components to the normalization of the wave functions decreases exponentially

  19. The effect of seismic motion characteristics on the inelastic response reduction of cylindrical shell structures

    International Nuclear Information System (INIS)

    Hagiwara, Y.; Yamamoto, K.; Akiyama, H.

    1993-01-01

    Reactor vessels of FBR are cylindrical shell structures, whose critical failure mode during earthquakes is plastic buckling in shear or bending mode. In buckling prevention of the vessels, it is of primary importance to realistically evaluate the plastic response reduction effect in the pre-buckling stage. Though the authors have already proposed a empirical formula to estimate the response reduction effect, the formula depends only on the pre-buckling ductility factor in the evaluation for the purpose of easy design practice. In this study, the effect of seismic motion characteristics on the response reduction effect was investigated both experimentally and numerically, and a improved version of the empirical expression of the reduction factor was proposed. In this new method, the response reduction effect is evaluated by an initial acceleration amplification factor in addition to the ductility of structures. (author)

  20. Origin of fine structure of the giant dipole resonance in s d -shell nuclei

    Science.gov (United States)

    Fearick, R. W.; Erler, B.; Matsubara, H.; von Neumann-Cosel, P.; Richter, A.; Roth, R.; Tamii, A.

    2018-04-01

    A set of high-resolution zero-degree inelastic proton scattering data on 24Mg, 28Si, 32S, and 40Ca provides new insight into the long-standing puzzle of the origin of fragmentation of the giant dipole resonance (GDR) in s d -shell nuclei. Understanding is achieved by comparison with random phase approximation calculations for deformed nuclei using for the first time a realistic nucleon-nucleon interaction derived from the Argonne V18 potential with the unitary correlation operator method and supplemented by a phenomenological three-nucleon contact interaction. A wavelet analysis allows one to extract significant scales both in the data and calculations characterizing the fine structure of the GDR. The fair agreement for scales in the range of a few hundred keV supports the surmise that the fine structure arises from ground-state deformation driven by α clustering.

  1. Four shells atomic model to computer the counting efficiency of electron-capture nuclides

    International Nuclear Information System (INIS)

    Grau Malonda, A.; Fernandez Martinez, A.

    1985-01-01

    The present paper develops a four-shells atomic model in order to obtain the efficiency of detection in liquid scintillation courting, Mathematical expressions are given to calculate the probabilities of the 229 different atomic rearrangements so as the corresponding effective energies. This new model will permit the study of the influence of the different parameters upon the counting efficiency for nuclides of high atomic number. (Author) 7 refs

  2. Electronic structure and electron dynamics at Si(100)

    Energy Technology Data Exchange (ETDEWEB)

    Weinelt, M. [Universitaet Erlangen-Nuernberg, Lehrstuhl fuer Festkoerperphysik, Erlangen (Germany); Max-Born-Institut, Berlin (Germany); Kutschera, M.; Schmidt, R.; Orth, C.; Fauster, T. [Universitaet Erlangen-Nuernberg, Lehrstuhl fuer Festkoerperphysik, Erlangen (Germany); Rohlfing, M. [International University Bremen, School of Engineering and Science, P.O. Box 750 561, Bremen (Germany)

    2005-02-01

    The electronic structure and electron dynamics at a Si(100) surface is studied by two-photon photoemission (2PPE). At 90 K the occupied D{sub up} dangling-bond state is located 150{+-}50 meV below the valence-band maximum (VBM) at the center of the surface Brillouin zone anti {gamma} and exhibits an effective hole mass of (0.5{+-}0.15)m{sub e}. The unoccupied D{sub down} band has a local minimum at anti {gamma} at 650{+-}50 meV above the VBM and shows strong dispersion along the dimer rows of the c(4 x 2) reconstructed surface. At 300 K the D{sub down} position shifts comparable to the Si conduction-band minimum by 40 meV to lower energies but the dispersion of the dangling-bond states is independent of temperature. The surface band bending for p-doped silicon is less than 30 meV, while acceptor-type defects cause significant and preparation-dependent band bending on n-doped samples. 2PPE spectra of Si(100) are dominated by interband transitions between the occupied and unoccupied surface states and emission out of transiently and permanently charged surface defects. Including electron-hole interaction in many-body calculations of the quasi-particle band structure leads us to assign a dangling-bond split-off state to a quasi-one-dimensional surface exciton with a binding energy of 130 meV. Electrons resonantly excited to the unoccupied D{sub down} dangling-bond band with an excess energy of about 350 meV need 1.5{+-}0.2 ps to scatter via phonon emission to the band bottom at anti {gamma} and relax within 5 ps with an excited hole in the occupied surface band to form an exciton living for nanoseconds. (orig.)

  3. Load requirements for maintaining structural integrity of Hanford single-shell tanks during waste feed delivery and retrieval activities

    International Nuclear Information System (INIS)

    JULYK, L.J.

    1999-01-01

    This document provides structural load requirements and their basis for maintaining the structural integrity of the Hanford Single-Shell Tanks during waste feed delivery and retrieval activities. The requirements are based on a review of previous requirements and their basis documents as well as load histories with particular emphasis on the proposed lead transfer feed tanks for the privatized vitrification plant

  4. Diamond surface: atomic and electronic structure

    International Nuclear Information System (INIS)

    Pate, B.B.

    1984-01-01

    Experimental studies of the diamond surface (with primary emphasis on the (111) surface) are presented. Aspects of the diamond surface which are addressed include (1) the electronic structure, (2) the atomic structure, and (3) the effect of termination of the lattice by foreign atoms. Limited studies of graphite are discussed for comparison with the diamond results. Experimental results from valence band and core level photoemission spectroscopy (PES), Auger electron spectroscopy (AES), low energy electron diffraction (LEED), and carbon 1s near edge x-ray absorption fine structure (NEXAFS) spectroscopy (both the total electron yield (TEY) and Auger electron yield (AEY) techniques) are used to study and characterize both the clean and hydrogenated surface. In addition, the interaction of hydrogen with the diamond surface is examined using results from vibrational high resolution low energy electron loss spectroscopy (in collaboration with Waclawski, Pierce, Swanson, and Celotta at the National Bureau of Standards) and photon stimulated ion desorption (PSID) yield at photon energies near the carbon k-edge (hv greater than or equal to 280 eV). Both EELS and PSID verify that the mechanically polished 1 x 1 surface is hydrogen terminated and also that the reconstructed surface is hydrogen free. The (111) 2 x 2/2 x 1 reconstructed surface is obtained from the hydrogenated (111) 1 x 1:H surface by annealing to approx. = 1000 0 C. We observe occupied intrinsic surface states and a surface chemical shift (0.95 +- 0.1 eV) to lower binding energy of the carbon 1s level on the hydrogen-free reconstructed surface. Atomic hydrogen is found to be reactive with the reconstructed surface, while molecular hydrogen is relatively inert. Exposure of the reconstructed surface to atomic hydrogen results in chemisorption of hydrogen and removal of the intrinsic surface state emission in and near the band gap region

  5. Mechanical properties of crossed-lamellar structures in biological shells: A review.

    Science.gov (United States)

    Li, X W; Ji, H M; Yang, W; Zhang, G P; Chen, D L

    2017-10-01

    The self-fabrication of materials in nature offers an alternate and powerful solution towards the grand challenge of designing advanced structural materials, where strength and toughness are always mutually exclusive. Crossed-lamellar structures are the most common microstructures in mollusks that are composed of aragonites and a small amount of organic materials. Such a distinctive composite structure has a fracture toughness being much higher than that of pure carbonate mineral. These structures exhibiting complex hierarchical microarchitectures that span several sub-level lamellae from microscale down to nanoscale, can be grouped into two types, i.e., platelet-like and fiber-like crossed-lamellar structures based on the shapes of basic building blocks. It has been demonstrated that these structures have a great potential to strengthen themselves during deformation. The observed underlying toughening mechanisms include microcracking, channel cracking, interlocking, uncracked-ligament bridging, aragonite fiber bridging, crack deflection and zig-zag, etc., which play vital roles in enhancing the fracture resistance of shells with the crossed-lamellar structures. The exploration and utilization of these important toughening mechanisms have attracted keen interests of materials scientists since they pave the way for the development of bio-inspired advanced composite materials for load-bearing structural applications. This article is aimed to review the characteristics of hierarchical structures and the mechanical properties of two kinds of crossed-lamellar structures, and further summarize the latest advances and biomimetic applications based on the unique crossed-lamellar structures. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Hierarchical structure observation and nanoindentation size effect characterization for a limnetic shell

    Science.gov (United States)

    Song, Jingru; Fan, Cuncai; Ma, Hansong; Wei, Yueguang

    2015-06-01

    In the present research, hierarchical structure observation and mechanical property characterization for a type of biomaterial are carried out. The investigated biomaterial is Hyriopsis cumingii, a typical limnetic shell, which consists of two different structural layers, a prismatic "pillar" structure and a nacreous "brick and mortar" structure. The prismatic layer looks like a "pillar forest" with variation-section pillars sized on the order of several tens of microns. The nacreous material looks like a "brick wall" with bricks sized on the order of several microns. Both pillars and bricks are composed of nanoparticles. The mechanical properties of the hierarchical biomaterial are measured by using the nanoindentation test. Hardness and modulus are measured for both the nacre layer and the prismatic layer, respectively. The nanoindentation size effects for the hierarchical structural materials are investigated experimentally. The results show that the prismatic nanostructured material has a higher stiffness and hardness than the nacre nanostructured material. In addition, the nanoindentation size effects for the hierarchical structural materials are described theoretically, by using the trans-scale mechanics theory considering both strain gradient effect and the surface/interface effect. The modeling results are consistent with experimental ones.

  7. Electronic structure and electron momentum density in TiSi

    Energy Technology Data Exchange (ETDEWEB)

    Ghaleb, A.M. [Department of Physics, College of Science, University of Kirkuk, Kirkuk (Iraq); Mohammad, F.M. [Department of Physics, College of Science, University of Tikreet, Tikreet (Iraq); Sahariya, Jagrati [Department of Physics, University College of Science, M.L. Sukhadia University, Udaipur 313001, Rajasthan (India); Sharma, Mukesh [Physics Division, Forensic Science Laboratory, Jaipur, Rajasthan (India); Ahuja, B.L., E-mail: blahuja@yahoo.com [Department of Physics, University College of Science, M.L. Sukhadia University, Udaipur 313001, Rajasthan (India)

    2013-03-01

    We report the electron momentum density in titanium monosilicide using {sup 241}Am Compton spectrometer. Experimental Compton profile has been compared with the theoretical profiles computed using linear combination of atomic orbitals (LCAO). The energy bands, density of states and Fermi surface structures of TiSi are reported using the LCAO and the full potential linearized augmented plane wave methods. Theoretical anisotropies in directional Compton profiles are interpreted in terms of energy bands. To confirm the conducting behavior, we also report the real space analysis of experimental Compton profile of TiSi.

  8. The sustained-release behavior and in vitro and in vivo transfection of pEGFP-loaded core-shell-structured chitosan-based composite particles

    Science.gov (United States)

    Wang, Yun; Lin, Fu-xing; Zhao, Yu; Wang, Mo-zhen; Ge, Xue-wu; Gong, Zheng-xing; Bao, Dan-dan; Gu, Yu-fang

    2014-01-01

    Novel submicron core-shell-structured chitosan-based composite particles encapsulated with enhanced green fluorescent protein plasmids (pEGFP) were prepared by complex coacervation method. The core was pEGFP-loaded thiolated N-alkylated chitosan (TACS) and the shell was pH- and temperature-responsive hydroxybutyl chitosan (HBC). pEGFP-loaded TACS-HBC composite particles were spherical, and had a mean diameter of approximately 120 nm, as measured by transmission electron microscopy and particle size analyzer. pEGFP showed sustained release in vitro for >15 days. Furthermore, in vitro transfection in human embryonic kidney 293T and human cervix epithelial cells, and in vivo transfection in mice skeletal muscle of loaded pEGFP, were investigated. Results showed that the expression of loaded pEGFP, both in vitro and in vivo, was slow but could be sustained over a long period. pEGFP expression in mice skeletal muscle was sustained for >60 days. This work indicates that these submicron core-shell-structured chitosan-based composite particles could potentially be used as a gene vector for in vivo controlled gene transfection. PMID:25364253

  9. Double-shell Fe2O3 hollow box-like structure for enhanced photo-Fenton degradation of malachite green dye

    Science.gov (United States)

    Jiang, De Bin; Liu, Xiaoying; Xu, Xuan; Zhang, Yu Xin

    2018-01-01

    In this work we demonstrate the synthesis of novel Fe2O3 nanosheets with double-shell hollow morphology by replica molding from diatomite framework. The nanostructures of Fe2O3 nanosheets were examined by focused-ion-beam scanning electron microscopy (FIB/SEM), X-ray diffraction spectroscopy (XRD), Brunauer-Emmett-Teller (BET) specific surface area measurements and Fourier transform infrared (FT-IR) spectroscopy. The results reveal that (1) Pure Fe2O3 nanosheets were successfully obtained; (2) The double-shell Fe2O3 hollow structure achieved via the NaOH etching silica method was observed; (3) Fe2O3 nanosheets possessed uniformly distributed porous nanosheets. Such structural features enlarged the specific surface area of Fe2O3 nanosheets and led to more catalytic active sites. In the heterogeneous photo-Fenton reaction, the double-shell Fe2O3 hollow morphology exhibited excellent catalytic capability for the degradation of malachite green (MG) at circumneutral pH condition. Under optimum condition, MG solution was almost completely decolorized in 60 min (99.9%). The Fe2O3 nanosheets also showed good stability and recyclability, demonstrating great potential as a promising photo-Fenton catalyst for the effective degradation of MG dye in wastewater.

  10. Explicit Dynamic Finite Element Method for Predicting Implosion/Explosion Induced Failure of Shell Structures

    Directory of Open Access Journals (Sweden)

    Jeong-Hoon Song

    2013-01-01

    Full Text Available A simplified implementation of the conventional extended finite element method (XFEM for dynamic fracture in thin shells is presented. Though this implementation uses the same linear combination of the conventional XFEM, it allows for considerable simplifications of the discontinuous displacement and velocity fields in shell finite elements. The proposed method is implemented for the discrete Kirchhoff triangular (DKT shell element, which is one of the most popular shell elements in engineering analysis. Numerical examples for dynamic failure of shells under impulsive loads including implosion and explosion are presented to demonstrate the effectiveness and robustness of the method.

  11. Structure of s - p bonded metal clusters with 8, 20 and 40 valence electrons

    International Nuclear Information System (INIS)

    Kumar, V.

    1992-10-01

    From studies on some clusters of metals and semiconductors, there appear some similarities in the structure of clusters with a given number of atoms and having the number of valence electrons corresponding to a shell closing. Here we present results of the atomic and electronic structure of a few other clusters with 20 and 40 valence electrons, namely Sb 4 , Sn 5 and Sb 8 using the density functional molecular dynamics method. We suggest that the similarities in the structure and deviation from them may help to understand bonding characteristics in clusters and its evolution to bulk behaviour. Our results on Sb 8 cluster are preliminary but indicate that above room temperature its structure is two weakly interacting tetrahedra which is in general agreement with the observation of predominently antimony tetramers at T > 300 K. (author). 16 refs, 2 figs

  12. Enhanced visible light photocatalytic activity in SnO{sub 2}@g-C{sub 3}N{sub 4} core-shell structures

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Hao; Zhao, Xiaoru, E-mail: xrzhao@nwpu.edu.cn; Duan, Libing; Liu, Ruidi; Li, Hui

    2017-04-15

    Highlights: • Novel SnO{sub 2}@g-C{sub 3}N{sub 4} core-shell structures were successfully synthesized. • The core-shell structures exhibited enhanced visible light photocatalytic activity. • The enhanced photocatalytic activity was due to synergic action of SnO{sub 2} and g-C{sub 3}N{sub 4}. - Abstract: SnO{sub 2}@g-C{sub 3}N{sub 4} core-shell structures were successfully synthesized by simple calcination of SnO{sub 2} microspheres and urea in a muffle furnace. The investigation of morphologies and microstructures showed that g-C{sub 3}N{sub 4} was wrapped tightly on the surface of SnO{sub 2} microspheres with large intimate interface contact areas between the g-C{sub 3}N{sub 4} shells and SnO{sub 2} cores. The X-ray photoelectron spectroscopy results and photoluminescence spectra demonstrated that the intimate interface contacts could facilitate the transfer and separation of the photogenerated charge carriers at their interface, thus the recombination of the photogenerated electron-hole pairs was impeded. The photocatalytic activity of the synthesized composites was evaluated by the photodegradation of methyl orange under visible light irradiation. It was found that SnO{sub 2}@g-C{sub 3}N{sub 4} exhibited higher photodegradation rate (k = 0.013 min{sup −1}) than that of g-C{sub 3}N{sub 4} (k = 0.008 min{sup −1}) and pure SnO{sub 2}. The enhanced photocatalytic activity could be attributed to the synergic action of SnO{sub 2} and g-C{sub 3}N{sub 4}.

  13. Synthesis of parallel and antiparallel core-shell triangular nanoparticles

    Science.gov (United States)

    Bhattacharjee, Gourab; Satpati, Biswarup

    2018-04-01

    Core-shell triangular nanoparticles were synthesized by seed mediated growth. Using triangular gold (Au) nanoparticle as template, we have grown silver (Ag) shellto get core-shell nanoparticle. Here by changing the chemistry we have grown two types of core-shell structures where core and shell is having same symmetry and also having opposite symmetry. Both core and core-shell nanoparticles were characterized using transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX) to know the crystal structure and composition of these synthesized core-shell nanoparticles. From diffraction pattern analysis and energy filtered TEM (EFTEM) we have confirmed the crystal facet in core is responsible for such two dimensional growth of core-shell nanostructures.

  14. Orbital momentum distribution and binding energies for the complete valence shell of molecular chlorine by electron momentum spectroscopy

    International Nuclear Information System (INIS)

    Frost, L.; Grisogono, A.M.; McCarthy, I.E.

    1986-10-01

    The complete valence shell binding energy spectrum (10-50 eV) of Cl 2 has been determined using electron momentum (binary (e,2e)) spectroscopy. The inner valence region, corresponding to 4σ u and 4σ g ionization, has been measured for the first time and shows extensive splitting of the ionization strength due to electron correlation effects. These measurements are compared with the results of many-body calculations using Green's function and CI methods employing unpolarised as well as polarised wave functions. Momentum distributions, measured in both the outer and inner valence regions, are compared with calculations using a range of unpolarised and polarised wave functions. Computed orbital density maps in momentum and position space for oriented Cl 2 molecules are discussed in comparison with the measured and calculated spherically averaged momentum distributions

  15. Quasi-spin method in the case of j-j coupling in a shell of equivalent atomic electrons

    International Nuclear Information System (INIS)

    Savichyus, E.G.; Kanyauskas, Yu.M.; Rudzikas, Z.B.

    1979-01-01

    Mathematical apparatus of the theory of multielectronic atoms and ions in the case of j-j coupling in a shell of equivalent electrons is built. Quasi-spin method is used. The scheme of the investigation is the following: 1. Tensorial properties of the operators in quasi-spin space are considered. 2. Matrix elements of these operators are built and with the help of Wigner-Eckart theorem the dependence of the matrix elements upon the projection, including the quasi-spin projection, of the quantity of electrons in jj-subshell, is determined. 3. Subgenealogical coefficients (genealogical coefficients presented in quasi-spin space) are determined and some of their properties are investigated. The tables of subgenealogical coefficients for j=5/2, 7/2 are presented

  16. Core-Shell Structuring of Pure Metallic Aerogels towards Highly Efficient Platinum Utilization for the Oxygen Reduction Reaction.

    Science.gov (United States)

    Cai, Bin; Hübner, René; Sasaki, Kotaro; Zhang, Yuanzhe; Su, Dong; Ziegler, Christoph; Vukmirovic, Miomir B; Rellinghaus, Bernd; Adzic, Radoslav R; Eychmüller, Alexander

    2018-03-05

    The development of core-shell structures remains a fundamental challenge for pure metallic aerogels. Here we report the synthesis of Pd x Au-Pt core-shell aerogels composed of an ultrathin Pt shell and a composition-tunable Pd x Au alloy core. The universality of this strategy ensures the extension of core compositions to Pd transition-metal alloys. The core-shell aerogels exhibited largely improved Pt utilization efficiencies for the oxygen reduction reaction and their activities show a volcano-type relationship as a function of the lattice parameter of the core substrate. The maximum mass and specific activities are 5.25 A mg Pt -1 and 2.53 mA cm -2 , which are 18.7 and 4.1 times higher than those of Pt/C, respectively, demonstrating the superiority of the core-shell metallic aerogels. The proposed core-based activity descriptor provides a new possible strategy for the design of future core-shell electrocatalysts. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Facile synthesis of core–shell structured PANI-Co{sub 3}O{sub 4} nanocomposites with superior electrochemical performance in supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Hai, Zhenyin [Key Laboratory of Instrumentation and Dynamic Measurement of Ministry of Education, North University of China, Taiyuan, Shanxi 030051 (China); Gao, Libo [Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Hong Kong SAR, Kowloon 999077 (Hong Kong); Zhang, Qiang [Key Laboratory of Instrumentation and Dynamic Measurement of Ministry of Education, North University of China, Taiyuan, Shanxi 030051 (China); Xu, Hongyan [School of Materials Science and Engineering, North University of China, Taiyuan, Shanxi 030051 (China); Cui, Danfeng; Zhang, Zengxing [Key Laboratory of Instrumentation and Dynamic Measurement of Ministry of Education, North University of China, Taiyuan, Shanxi 030051 (China); Tsoukalas, Dimitris [Department of Applied Physics, National Technical University of Athens, Zografou GR-15780 (Greece); Tang, Jun; Yan, Shubin [Key Laboratory of Instrumentation and Dynamic Measurement of Ministry of Education, North University of China, Taiyuan, Shanxi 030051 (China); Xue, Chenyang, E-mail: xuechenyang@nuc.edu.cn [Key Laboratory of Instrumentation and Dynamic Measurement of Ministry of Education, North University of China, Taiyuan, Shanxi 030051 (China)

    2016-01-15

    Graphical abstract: - Highlights: • PANI-Co{sub 3}O{sub 4} is synthesized by carbon-assisted and in situ polymerization methods. • PANI coating improves the properties of Co{sub 3}O{sub 4} affecting electrochemical performance. • The nanocomposites exhibit a high specific capacitance of 1184 F g{sup −1} at 1.25 A g{sup −1}. - Abstract: Core–shell structured PANI-Co{sub 3}O{sub 4} nanocomposites for supercapacitor applications were synthesized by combination of carbon-assisted method and in situ polymerization method. The crystalline structure, optical band gap, morphology, and hydrophilic property, as the major factors affecting the performances of supercapacitors, were investigated by X-ray diffraction (XRD), UV–vis spectrophotometry (UV–vis), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and water contact angle (WCA). The core–shell structured PANI-Co{sub 3}O{sub 4} nanocomposites are characterized by amorphous PANI, small bandgaps, large surface area and favorable hydrophilicity, which indicates the superior electrochemical performances of the nanocomposites as electrode material for supercapacitors. Cyclic voltammetry (CV), galvanostatic charge/discharge and electrochemical impedance spectroscopy (EIS) measurements were conducted in 6 M KOH aqueous solution to evaluate the electrochemical performances. The results shows that core–shell structured PANI-Co{sub 3}O{sub 4} nanocomposites exhibit a high specific capacitance of 1184 F g{sup −1} at 1.25 A g{sup −1}, excellent cycling stability of a capacitance retention of 84.9% after 1000 galvanostatic charge/discharge cycles, good electrical conductivity and ion diffusion behavior.

  18. Polyaniline/multi-walled carbon nanotubes composite with core-shell structures as a cathode material for rechargeable lithium-polymer cells

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Pan [School of Marine Science and Technology, Harbin Institute of Technology, Weihai 264209 (China); Han, Jia-Jun, E-mail: hanjiajunhitweihai@163.com [School of Marine Science and Technology, Harbin Institute of Technology, Weihai 264209 (China); Jiang, Li-Feng [Dalian Chemical Institute of Chinese Academy of Sciences, Dalian 116011 (China); Li, Zhao-Yu; Cheng, Jin-Ning [School of Marine Science and Technology, Harbin Institute of Technology, Weihai 264209 (China)

    2017-04-01

    Highlights: • The polyaniline multi-walled carbon nanotubes composite with core-shell structures was synthetized via in situ chemical oxidative polymerization, and the materials were characterized by physical and chemical methods. • The PANI/WMCNTs was synthetized via in situ chemical oxidative polymerization with core-shell structures. • The WMCNTs highly enhanced the conductivity of composites. • The comopsites were more conducive to the intercalation and deintercalation of anions and cations. • The much better performance as the cathode for lithium-ion cells was acquired for the composites. • The composites are low cost and eco-friendly which have a good prospect in future. - Abstract: The aniline was polymerized onto functionalized multi-walled carbon nanotubes in order to obtain a cathode material with core-shell structures for lithium batteries. The structure and morphology of the samples were investigated by Fourier transform infrared spectroscopy analysis, scanning electron microscope, transmission electron microscope and X-ray diffraction. The electrochemical properties of the composite were characterized by the cyclic voltammetry, the charge/discharge property, coulombic efficiency, and ac impedance spectroscopy in detail. At a constant current density of 0.2 C, the first specific discharge capacity of the reduced and oxidized PANI/WMCNTs were 181.8 mAh/g and 135.1 mAh/g separately, and the capacity retention rates were corresponding to 76.75% and 86.04% for 100 cycles with 99% coulombic efficiency. It was confirmed that the CNTs obviously enhanced the conductivity and electrochemical performance of polyaniline, and compared with the pure PANI, the reduced composite possessed a quite good performance for the cathode of lithium batteries.

  19. 3D Printed structural electronics: embedding and connecting electronic components into freeform electronic devices

    NARCIS (Netherlands)

    Maalderink, H.H.H.; Bruning, F.B.J.; Schipper, M.M.R. de; Werff, J.J.J. van der; Germs, W.W.C.; Remmers, J.J.C.; Meinders, E.R.

    2018-01-01

    The need for personalised and smart products drives the development of structural electronics with mass-customisation capability. A number of challenges need to be overcome in order to address the potential of complete free form manufacturing of electronic devices. One key challenge is the

  20. 3D Printed structural electronics : embedding and connecting electronic components into freeform electronic devices

    NARCIS (Netherlands)

    Maalderink, H.H.; Bruning, F.B.J.; de Schipper, M.R.; van der Werff, J.J.; Germs, W.C.; Remmers, J.J.C.; Meinders, E.R.

    2018-01-01

    The need for personalised and smart products drives the development of structural electronics with mass-customisation capability. A number of challenges need to be overcome in order to address the potential of complete free form manufacturing of electronic devices. One key challenge is the

  1. Electronic structure of super heavy atoms revisited

    International Nuclear Information System (INIS)

    Gitman, D M; Levin, A D; Tyutin, I V; Voronov, B L

    2013-01-01

    The electronic structure of an atom with Z ⩽ Z c = 137 can be described by the Dirac equation with the Coulomb field of a point charge Ze. It was believed that the Dirac equation with Z > Z c poses difficulties because the formula for the lower energy level of the Dirac Hamiltonian formally gives imaginary eigenvalues. But a strict mathematical consideration shows that difficulties with the electronic spectrum for Z > Z c do not arise if the Dirac Hamiltonian is correctly defined as a self-adjoint operator. In this paper, we briefly summarize the main physical results of that consideration in a form suitable for physicists with some additional new details and numerical calculations of the electronic spectra. (comment)

  2. Effect of double-shell structure on reduction of field errors in the STP-3(M) reversed-field pinch

    International Nuclear Information System (INIS)

    Yamada, S.; Masamune, S.; Nagata, A.; Arimoto, H.; Oshiyama, H.; Sato, K.I.

    1988-08-01

    Reversed-field pinch (RFP) operation on STP-3 (M) proved that the adition of a quasistational vertical field B sub(perpendicular) together with large reduction of irregular magnetic field at the shell gap could remarkably improve properties of the plasma confinement. Here, the gaps of a thick shell is wholely covered with the single primary coil having a shell shape. The measured field error at the gap is as small as 7.5 % of the poloidal field. The application of B sub(perpendicular) sets the plasma at a more perfect equilibrium. In this operation, the plasma resistivety much decreased by a factor 2 and the electron temperature rose up to 0.8 keV. (author)

  3. Calculated Electronic Behavior and Spectrum of Mg+@C60 Using a Simple Jellium-shell Model

    Directory of Open Access Journals (Sweden)

    H. A. Schuessler

    2004-11-01

    Full Text Available Abstract: We present a method for calculating the energy levels and wave functions of any atom or ion with a single valence electron encapsulated in a Fullerene cage using a jelluim-shell model. The valence electron-core interaction is represented by a one-body pseudo-potential obtained through density functional theory with strikingly accurate parameters for Mg+ and which reduces to a purely Coulombic interaction in the case of H. We find that most energy states are affected little by encapsulation. However, when either the electron in the non-encapsulated species has a high probability of being near the jellium cage, or when the cage induces a maximum electron probability density within it, the energy levels shift considerably. Mg+ shows behavior similar to that of H, but since its wave functions are broader, the changes in its energy levels from encapsulation are slightly more pronounced. Agreement with other computational work as well as experiment is excellent and the method presented here is generalizable to any encapsulated species where a one-body electronic pseudo-potential for the free atom (or ion is available. Results are also presented for off-center hydrogen, where a ground state energy minimum of -14.01 eV is found at a nuclear displacement of around 0.1 Å.

  4. Electronic band structures of binary skutterudites

    International Nuclear Information System (INIS)

    Khan, Banaras; Aliabad, H.A. Rahnamaye; Saifullah; Jalali-Asadabadi, S.; Khan, Imad; Ahmad, Iftikhar

    2015-01-01

    The electronic properties of complex binary skutterudites, MX 3 (M = Co, Rh, Ir; X = P, As, Sb) are explored, using various density functional theory (DFT) based theoretical approaches including Green's Function (GW) as well as regular and non-regular Tran Blaha modified Becke Jhonson (TB-mBJ) methods. The wide range of calculated bandgap values for each compound of this skutterudites family confirm that they are theoretically as challenging as their experimental studies. The computationally expensive GW method, which is generally assume to be efficient in the reproduction of the experimental bandgaps, is also not very successful in the calculation of bandgaps. In this article, the issue of the theoretical bandgaps of these compounds is resolved by reproducing the accurate experimental bandgaps, using the recently developed non-regular TB-mBJ approach, based on DFT. The effectiveness of this technique is due to the fact that a large volume of the binary skutterudite crystal is empty and hence quite large proportion of electrons lie outside of the atomic spheres, where unlike LDA and GGA which are poor in the treatment of these electrons, this technique properly treats these electrons and hence reproduces the clear electronic picture of these compounds. - Highlights: • Theoretical and experimental electronic band structures of binary skutterudites are reviewed. • The literature reveals that none of the existing theoretical results are consistent with the experiments. • GW, regular and non-regular TB-mBJ methods are used to reproduce the correct results. • The GW and regular TB-mBJ results are better than the available results in literature. • However, non-regular TB-mBJ reproduces the correct experimental band structures

  5. Electronic band structures of binary skutterudites

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Banaras [Center for Computational Materials Science, University of Malakand, Chakdara (Pakistan); Department of Physics, University of Malakand, Chakdara (Pakistan); Aliabad, H.A. Rahnamaye [Department of Physics, Hakim Sabzevari University, Sabzevar (Iran, Islamic Republic of); Saifullah [Center for Computational Materials Science, University of Malakand, Chakdara (Pakistan); Department of Physics, University of Malakand, Chakdara (Pakistan); Jalali-Asadabadi, S. [Department of Physics, Faculty of Science, University of Isfahan (UI), 81744 Isfahan (Iran, Islamic Republic of); Khan, Imad [Center for Computational Materials Science, University of Malakand, Chakdara (Pakistan); Department of Physics, University of Malakand, Chakdara (Pakistan); Ahmad, Iftikhar, E-mail: ahma5532@gmail.com [Center for Computational Materials Science, University of Malakand, Chakdara (Pakistan); Department of Physics, University of Malakand, Chakdara (Pakistan)

    2015-10-25

    The electronic properties of complex binary skutterudites, MX{sub 3} (M = Co, Rh, Ir; X = P, As, Sb) are explored, using various density functional theory (DFT) based theoretical approaches including Green's Function (GW) as well as regular and non-regular Tran Blaha modified Becke Jhonson (TB-mBJ) methods. The wide range of calculated bandgap values for each compound of this skutterudites family confirm that they are theoretically as challenging as their experimental studies. The computationally expensive GW method, which is generally assume to be efficient in the reproduction of the experimental bandgaps, is also not very successful in the calculation of bandgaps. In this article, the issue of the theoretical bandgaps of these compounds is resolved by reproducing the accurate experimental bandgaps, using the recently developed non-regular TB-mBJ approach, based on DFT. The effectiveness of this technique is due to the fact that a large volume of the binary skutterudite crystal is empty and hence quite large proportion of electrons lie outside of the atomic spheres, where unlike LDA and GGA which are poor in the treatment of these electrons, this technique properly treats these electrons and hence reproduces the clear electronic picture of these compounds. - Highlights: • Theoretical and experimental electronic band structures of binary skutterudites are reviewed. • The literature reveals that none of the existing theoretical results are consistent with the experiments. • GW, regular and non-regular TB-mBJ methods are used to reproduce the correct results. • The GW and regular TB-mBJ results are better than the available results in literature. • However, non-regular TB-mBJ reproduces the correct experimental band structures.

  6. Synthesis and morphology of iron-iron oxide core-shell nanoparticles produced by high pressure gas condensation

    NARCIS (Netherlands)

    Xing, Lijuan; ten Brink, Gert H.; Chen, Bin; Schmidt, Franz P.; Haberfehlner, Georg; Hofer, Ferdinand; Kooi, Bart J.; Palasantzas, Georgios

    2016-01-01

    Core-shell structured Fe nanoparticles (NPs) produced by high pressure magnetron sputtering gas condensation were studied using transmission electron microscopy (TEM) techniques, electron diffraction, electron energy-loss spectroscopy (EELS), tomographic reconstruction, and Wulff shape construction

  7. Retrieving transient conformational molecular structure information from inner-shell photoionization of laser-aligned molecules

    Science.gov (United States)

    Wang, Xu; Le, Anh-Thu; Yu, Chao; Lucchese, R. R.; Lin, C. D.

    2016-01-01

    We discuss a scheme to retrieve transient conformational molecular structure information using photoelectron angular distributions (PADs) that have averaged over partial alignments of isolated molecules. The photoelectron is pulled out from a localized inner-shell molecular orbital by an X-ray photon. We show that a transient change in the atomic positions from their equilibrium will lead to a sensitive change in the alignment-averaged PADs, which can be measured and used to retrieve the former. Exploiting the experimental convenience of changing the photon polarization direction, we show that it is advantageous to use PADs obtained from multiple photon polarization directions. A simple single-scattering model is proposed and benchmarked to describe the photoionization process and to do the retrieval using a multiple-parameter fitting method. PMID:27025410

  8. A novel approach to preparing magnetic protein microspheres with core-shell structure

    Science.gov (United States)

    Jiang, Wei; Sun, Zhendong; Li, Fengsheng; Chen, Kai; Liu, Tianyu; Liu, Jialing; Zhou, Tianle; Guo, Rui

    2011-03-01

    Magnetic protein microspheres with core-shell structure were prepared through a novel approach based on the sonochemical method and the emulsion solvent evaporation method. The microspheres are composed of the oleic acid and undecylenic acid modified Fe 3O 4 cores and coated with globular bovine serum albumin (BSA). Under an optimized condition, up to 57.8 wt% of approximately 10 nm superparamagnetic Fe 3O 4 nanoparticles could be uniformly encapsulated into the BSA microspheres with the diameter of approximately 160 nm and the high saturation magnetization of 38.5 emu/g, besides of the abundant functional groups. The possible formation mechanism of magnetic microspheres was discussed in detail.

  9. Electronic structure and static dipole polarizability of C60-C240

    International Nuclear Information System (INIS)

    Zope, Rajendra R

    2008-01-01

    The electronic structure of C 60 -C 240 and its first-order response to a static electric field is studied by an all-electron density functional theory calculation using large polarized Gaussian basis sets. Our results show that the outer C 240 shell almost completely shields the inner C 60 as inferred from the practically identical values of dipole polarizability of the C 60 -C 240 onion (449 A 3 ) and that of the isolated C 240 fullerene (441 A 3 ). The C 60 -C 240 is thus a near-perfect Faraday cage

  10. Accelerated safety analyses - structural analyses Phase I - structural sensitivity evaluation of single- and double-shell waste storage tanks

    International Nuclear Information System (INIS)

    Becker, D.L.

    1994-11-01

    Accelerated Safety Analyses - Phase I (ASA-Phase I) have been conducted to assess the appropriateness of existing tank farm operational controls and/or limits as now stipulated in the Operational Safety Requirements (OSRs) and Operating Specification Documents, and to establish a technical basis for the waste tank operating safety envelope. Structural sensitivity analyses were performed to assess the response of the different waste tank configurations to variations in loading conditions, uncertainties in loading parameters, and uncertainties in material characteristics. Extensive documentation of the sensitivity analyses conducted and results obtained are provided in the detailed ASA-Phase I report, Structural Sensitivity Evaluation of Single- and Double-Shell Waste Tanks for Accelerated Safety Analysis - Phase I. This document provides a summary of the accelerated safety analyses sensitivity evaluations and the resulting findings

  11. Gastropod shells: a dynamic resource that helps shape benthic community structure. [Calliactis tricolor; Pagurus pollicaris; Calappa flammea; Octopus joubini; Panulirus argus

    Energy Technology Data Exchange (ETDEWEB)

    McLean, R

    1983-01-01

    Empty gastropod shells are an important resource for many animals in shallow benthic marine communities. Shells provide shelter for hermit crabs, octopuses, and fishes, provide attachment substratum for hermit crab symbionts, and directly or indirectly modify hermit crab predation. Creation of an empty shell due to predation of one gastropod on another and acquisition of that shell by a hermit crab are two key events in the subsequent use of that shell. Shells of different gastropod species and the species of hermit crab acquiring them affect the symbiont complement that attaches to the shell, which in turn may affect future shell use by other symbionts. Certain shell types worn by the hermit crab, Pagurus pollicaris Say, are positively associated with the symbiotic sea anemone, Calliactis tricolor (Lesueur), which protects the hermit crab from predation by the crab, Calappa flammea (Herbst), and possibly from the octopus, Octopus joubini Robson. Shells of other species of gastropods are resistant to being crushed by the spiny lobster, Panulirus argus (Latreille). The inter- and intraspecific interactions centered on the gastropod shell are termed a ''habitat web.'' The potential of the shell to limit the size and distribution of animal populations demonstrates how this resource helps shape community structure.

  12. Electronic structure of Pu carbides: photoelectron spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Gouder, T.; Havela, L.; Shick, Alexander; Huber, F.

    2008-01-01

    Roč. 403, č. 5-9 (2008), s. 852-853 ISSN 0921-4526 R&D Projects: GA AV ČR(CZ) IAA100100530 Grant - others:EU(XE) RITA -CT-2006-026176 Institutional research plan: CEZ:AV0Z10100520 Keywords : photoemission * electronic structure * plutonium Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.822, year: 2008

  13. Electrochemical performance and structure evolution of core-shell nano-ring α-Fe{sub 2}O{sub 3}@Carbon anodes for lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Yan-Hui, E-mail: sunyanhui0102@163.com; Liu, Shan; Zhou, Feng-Chen; Nan, Jun-Min

    2016-12-30

    Core-shell nano-ring α-Fe{sub 2}O{sub 3}@Carbon (CSNR) composites with different carbon content (CSNR-5%C and CSNR-13%C) are synthesized using a hydrothermal method by controlling different amounts of glucose and α-Fe{sub 2}O{sub 3} nano-rings with further annealing. The CSNR electrodes exhibit much improved specific capacity, cycling stability and rate capability compared with that of bare nano-ring α-Fe{sub 2}O{sub 3} (BNR), which is attributed to the core-shell nano-ring structure of CSNR. The carbon shell in the inner and outer surface of CSNR composite can increase electron conductivity of the electrode and inhibit the volume change of α-Fe{sub 2}O{sub 3} during discharge/charge processes, and the nano-ring structure of CSNR can buffer the volume change too. The CSNR-5%C electrode shows super high initial discharge/charge capacities of 1570/1220 mAh g{sup −1} and retains 920/897 mAh g{sup −1} after 200 cycles at 500 mA g{sup −1} (0.5C). Even at 2000 mA g{sup −1} (2C), the electrode delivers the initial capacities of 1400/900 mAh g{sup −1}, and still maintains 630/610 mAh g{sup −1} after 200 cycles. The core-shell nano-rings opened during cycling and rebuilt a new flower-like structure consisting of α-Fe{sub 2}O{sub 3}@Carbon nano-sheets. The space among the nano-sheet networks can further buffer the volume expansion of α-Fe{sub 2}O{sub 3} and facilitate the transportation of electrons and Li{sup +} ions during the charge/discharge processes, which increases the capacity and rate capability of the electrode. It is the first time that the evolution of core-shell α-Fe{sub 2}O{sub 3}@Carbon changing to flower-like networks during lithiation/de-lithiation has been reported.

  14. Electrochemical performance and structure evolution of core-shell nano-ring α-Fe_2O_3@Carbon anodes for lithium-ion batteries

    International Nuclear Information System (INIS)

    Sun, Yan-Hui; Liu, Shan; Zhou, Feng-Chen; Nan, Jun-Min

    2016-01-01

    Core-shell nano-ring α-Fe_2O_3@Carbon (CSNR) composites with different carbon content (CSNR-5%C and CSNR-13%C) are synthesized using a hydrothermal method by controlling different amounts of glucose and α-Fe_2O_3 nano-rings with further annealing. The CSNR electrodes exhibit much improved specific capacity, cycling stability and rate capability compared with that of bare nano-ring α-Fe_2O_3 (BNR), which is attributed to the core-shell nano-ring structure of CSNR. The carbon shell in the inner and outer surface of CSNR composite can increase electron conductivity of the electrode and inhibit the volume change of α-Fe_2O_3 during discharge/charge processes, and the nano-ring structure of CSNR can buffer the volume change too. The CSNR-5%C electrode shows super high initial discharge/charge capacities of 1570/1220 mAh g"−"1 and retains 920/897 mAh g"−"1 after 200 cycles at 500 mA g"−"1 (0.5C). Even at 2000 mA g"−"1 (2C), the electrode delivers the initial capacities of 1400/900 mAh g"−"1, and still maintains 630/610 mAh g"−"1 after 200 cycles. The core-shell nano-rings opened during cycling and rebuilt a new flower-like structure consisting of α-Fe_2O_3@Carbon nano-sheets. The space among the nano-sheet networks can further buffer the volume expansion of α-Fe_2O_3 and facilitate the transportation of electrons and Li"+ ions during the charge/discharge processes, which increases the capacity and rate capability of the electrode. It is the first time that the evolution of core-shell α-Fe_2O_3@Carbon changing to flower-like networks during lithiation/de-lithiation has been reported.

  15. Electrochemical performance and structure evolution of core-shell nano-ring α-Fe2O3@Carbon anodes for lithium-ion batteries

    Science.gov (United States)

    Sun, Yan-Hui; Liu, Shan; Zhou, Feng-Chen; Nan, Jun-Min

    2016-12-01

    Core-shell nano-ring α-Fe2O3@Carbon (CSNR) composites with different carbon content (CSNR-5%C and CSNR-13%C) are synthesized using a hydrothermal method by controlling different amounts of glucose and α-Fe2O3 nano-rings with further annealing. The CSNR electrodes exhibit much improved specific capacity, cycling stability and rate capability compared with that of bare nano-ring α-Fe2O3 (BNR), which is attributed to the core-shell nano-ring structure of CSNR. The carbon shell in the inner and outer surface of CSNR composite can increase electron conductivity of the electrode and inhibit the volume change of α-Fe2O3 during discharge/charge processes, and the nano-ring structure of CSNR can buffer the volume change too. The CSNR-5%C electrode shows super high initial discharge/charge capacities of 1570/1220 mAh g-1 and retains 920/897 mAh g-1 after 200 cycles at 500 mA g-1 (0.5C). Even at 2000 mA g-1 (2C), the electrode delivers the initial capacities of 1400/900 mAh g-1, and still maintains 630/610 mAh g-1 after 200 cycles. The core-shell nano-rings opened during cycling and rebuilt a new flower-like structure consisting of α-Fe2O3@Carbon nano-sheets. The space among the nano-sheet networks can further buffer the volume expansion of α-Fe2O3 and facilitate the transportation of electrons and Li+ ions during the charge/discharge processes, which increases the capacity and rate capability of the electrode. It is the first time that the evolution of core-shell α-Fe2O3@Carbon changing to flower-like networks during lithiation/de-lithiation has been reported.

  16. Structural and electronic properties of thallium compounds

    International Nuclear Information System (INIS)

    Paliwal, Neetu; Srivastava, Vipul

    2016-01-01

    The tight binding linear muffin-tin-orbital (TB-LMTO) method within the local density approximation (LDA has been used to calculate structural and electronic properties of thallium pnictides TlX (X=Sb, Bi) at high pressure. As a function of volume, the total energy is evaluated. Apart from this, the lattice parameter (a_0), bulk modulus (B_0), band structure (BS) and density of states (DOS) are calculated. From energy band diagram we observed metallic behaviour in TlSb and TlBi compounds. The values of equilibrium lattice constants and bulk modulus are agreed well with the available data.

  17. Structural and electronic properties of thallium compounds

    Energy Technology Data Exchange (ETDEWEB)

    Paliwal, Neetu, E-mail: neetumanish@gmail.com [Department of Physics, AISECT University Bhopal, 464993 (India); Srivastava, Vipul [Department of Engineering Physics, NRI Institute of Research & Technology, Raisen Road, Bhopal, 462021 (India)

    2016-05-06

    The tight binding linear muffin-tin-orbital (TB-LMTO) method within the local density approximation (LDA has been used to calculate structural and electronic properties of thallium pnictides TlX (X=Sb, Bi) at high pressure. As a function of volume, the total energy is evaluated. Apart from this, the lattice parameter (a{sub 0}), bulk modulus (B{sub 0}), band structure (BS) and density of states (DOS) are calculated. From energy band diagram we observed metallic behaviour in TlSb and TlBi compounds. The values of equilibrium lattice constants and bulk modulus are agreed well with the available data.

  18. Structural dynamics of electronic and photonic systems

    CERN Document Server

    Suhir, Ephraim; Steinberg, David S

    2011-01-01

    The proposed book will offer comprehensive and versatile methodologies and recommendations on how to determine dynamic characteristics of typical micro- and opto-electronic structural elements (printed circuit boards, solder joints, heavy devices, etc.) and how to design a viable and reliable structure that would be able to withstand high-level dynamic loading. Particular attention will be given to portable devices and systems designed for operation in harsh environments (such as automotive, aerospace, military, etc.)  In-depth discussion from a mechanical engineer's viewpoint will be conducte

  19. Soil structure interaction analysis for the Hanford Site 241-SY-101 double-shell waste storage tanks

    International Nuclear Information System (INIS)

    Giller, R.A.; Weiner, E.O.

    1991-09-01

    The 241-SY-101 tank is a double-shell waste storage tank buried in the 241-SY tank farm in the 200 West Area of the Hanford Site. This analysis addresses the effects of seismic soil-structure interaction on the tank structure and includes a parametric soil-structure interaction study addressing three configurations: two-dimensional soil structure, a two-dimensional structure-soil-structure, and a three-dimensional soil-structure interaction. This study was designed to determine an optimal method for addressing seismic-soil effects on underground storage tanks. The computer programs calculate seismic-soil pressures on the double-shell tank walls and and seismic acceleration response spectra in the tank. The results of this soil-structure interaction parametric study as produced by the computer programs are given in terms of seismic soil pressures and response spectra. The conclusions of this soil-structure interaction evaluation are that dynamically calculated soil pressures in the 241-SY-101 tank are significantly reduce from those using standard hand calculation methods and that seismic evaluation of underground double-shell waste storage tanks must consider soil-structure interaction effects in order to predict conservative structural response. Appendixes supporting this study are available in Volume 2 of this report

  20. Numerical simulation of deformation and fracture of space protective shell structures from concrete and fiber concrete under pulse loading

    International Nuclear Information System (INIS)

    Radchenko, P A; Batuev, S P; Radchenko, A V; Plevkov, V S

    2015-01-01

    This paper presents results of numerical simulation of interaction between aircraft Boeing 747-400 and protective shell of nuclear power plant. The shell is presented as complex multilayered cellular structure comprising layers of concrete and fiber concrete bonded with steel trusses. Numerical simulation was held three-dimensionally using the author's algorithm and software taking into account algorithms for building grids of complex geometric objects and parallel computations. The dynamics of stress-strain state and fracture of structure were studied. Destruction is described using two-stage model that allows taking into account anisotropy of elastic and strength properties of concrete and fiber concrete. It is shown that wave processes initiate destruction of shell cellular structure—cells start to destruct in unloading wave, originating after output of compression wave to the free surfaces of cells. (paper)

  1. Electronic structure of CdTe using GGA+U{sup SIC}

    Energy Technology Data Exchange (ETDEWEB)

    Menéndez-Proupin, E., E-mail: emenendez@uchile.cl [Departamento de Física, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, 780-0003 Ñuñoa, Santiago (Chile); Instituto de Energía Solar and Dept. Tecnologías Especiales, E.T.S.I. Telecomunicación, Universidad Politécnica de Madrid (Spain); Amézaga, A. [Departamento de Física, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, 780-0003 Ñuñoa, Santiago (Chile); Instituto de Ciencias Físicas y Matemáticas, Universidad Austral de Chile, Casilla 567, Valdivia (Chile); Cruz Hernández, N. [Departamento de Física Aplicada I, Escuela Técnica Superior de Ingeniería Informática, Universidad de Sevilla, Av. Reina Mercedes, 41012 Sevilla (Spain)

    2014-11-01

    A simple method to obtain a gap-corrected band structure of cadmium telluride within density functional theory is presented. On-site Coulomb self-interaction-like correction potential has been applied to the 5p-shell of Te and the 4d-shell of Cd. The predicted physical properties are similar to or better than those obtained with hybrid functionals and at largely reduced computational cost. In addition to the corrected electronic structure, the lattice parameters and the bulk modulus are improved. The relative stabilities of the different phases (zincblende, wurtzite, rocksalt and cinnabar) are preserved. The formation energy of the cadmium vacancy remains close to the values obtained from hybrid functional calculations.

  2. Electron emission relevant to inner-shell photoionization of condensed water studied by multi-electron coincidence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hikosaka, Y., E-mail: hikosaka@las.u-toyama.ac.jp [Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama 930-0194 (Japan); Mashiko, R.; Konosu, Y.; Soejima, K. [Department of Environmental Science, Niigata University, Niigata 950-2181 (Japan); Shigemasa, E. [UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585 (Japan); SOKENDAI, Okazaki 444-8585 (Japan)

    2016-11-15

    Highlights: • Multi-electron coincidence spectroscopy is applied to the study of electron emissions from condensed H2O molecules. • Coincidence Auger spectra are obtained for different photoelectron energies. • The energy distribution of the slow electrons ejected in the Auger decay is deduced from three-fold coincidences. - Abstract: Multi-electron coincidence spectroscopy using a magnetic-bottle electron spectrometer has been applied to the study of the Auger decay following O1s photoionization of condensed H{sub 2}O molecules. Coincidence Auger spectra are obtained for three different photoelectron energy ranges. In addition, the energy distribution of the slow electrons ejected in the Auger decay of the O1s core hole is deduced from three-fold coincidences.

  3. Scanning electron microscopy and swelling test of shrimp shell chitosan and chitosan-RGD scaffolds

    Science.gov (United States)

    Mandacan, M. C.; Yuniastuti, M.; Amir, L. R.; Idrus, E.; Suniarti, D. F.

    2017-08-01

    Shrimp shell chitosan and chitosan-RGD scaffold membranes are produced to be biocompatible with tissue engineering. Nonetheless, their architectural properties have not yet been studied. Analyze the architectural properties of chitosan and chitosan-RGD scaffolds. Analyze pore count and size, interpore distance, and porosity (using SEM testing and ImageJ analysis) and water absorption (using a swelling test). The properties of the chitosan and chitosan-RGD scaffolds were as follows, respectively. The pore counts were 225 and 153; pore size, 171.4 μam and 180.2 μam interpore distance, 105.7 μam and 101.4 μam porosity, 22% and 10.2%; and water absorption, 9.1 mgH2O/mgScaffold and 19.3 mgH2O/mgScaffold. The shrimp shell chitosan-RGD membrane scaffold was found to have architectural properties that make it more conducive to use in tissue engineering.

  4. Structure and interactions of calcite spherulites with α-chitin in the brown shrimp (Penaeus aztecus) shell

    International Nuclear Information System (INIS)

    Heredia, A.; Aguilar-Franco, M.; Magana, C.; Flores, C.; Pina, C.; Velazquez, R.; Schaeffer, T.E.; Bucio, L.; Basiuk, V.A.

    2007-01-01

    White spots form in the brown shrimp (Penaeus aztecus, Decapoda) shell during frozen storage. The mineral formed consists of calcite incorporated into an amorphous α-chitin matrix. We studied mechanisms of interaction of amorphous α-chitin macromolecules with hkl crystal planes to form highly ordered structures, as well as the role of specific sites in the biopolymer, which can be related to nucleation and spheroidal crystal growth. We used low vacuum scanning electron microscopy (LVSEM), X-ray powder diffraction (XRD), atomic force microscopy (AFM), Fourier-transform infrared spectroscopy (FT-IR), and molecular mechanics modeling (MM+ method). AFM images showed fingerprint distances in the biopolymer and a highly layered structure in the crystalline material. The presence of α-chitin, with a specific spatial distribution of radicals, is thought to be responsible for nucleation and to thermodynamically stabilize ions to form the spherulite crystalline phase, which are usually oval to spherical (0.10 to 200 μm in diameter). Our models of crystal-biopolymer interaction found high affinity of CO 3 2- anions in the (104) crystalline plane (the main plane in calcite monocrystals) to NH- groups of the biopolymer, as well as of the C=O in the biopolymer to Ca 2+ cations in the crystalline structure. These interactions explain the spherical growth and inhibition in some planes. The specific physicochemical interactions (docking of groups depending on their geometrical distribution) suggest that the biomineral structure is controlled by the biopolymer on a local scale. This information is useful for further design and improvement of (hybrid) materials for versatile application, from nanotechnology to biomedicine and engineering

  5. Structure and interactions of calcite spherulites with {alpha}-chitin in the brown shrimp (Penaeus aztecus) shell

    Energy Technology Data Exchange (ETDEWEB)

    Heredia, A. [Instituto de Ciencias Nucleares, Departamento de Quimica de Radiaciones y Radioquimica, UNAM, Circuito Exterior C.U. Apdo., Postal 70-543, 04510 Mexico, D.F. (Mexico); Physikalisches Institut and Center for Nanotechnology, Universitaet Muenster, Gievenbecker Weg 11, 48149 Muenster (Germany); Aguilar-Franco, M. [Instituto de Fisica, Depto de Fisicoquimica, UNAM, Circuito Exterior s/n, Ciudad Universitaria Apartado Postal 20-364 01000 Mexico D.F. (Mexico); Magana, C. [Instituto de Fisica, Depto de Estado Solido, UNAM, Circuito Exterior s/n, Ciudad Universitaria Apartado Postal 20-364 01000 Mexico D.F. (Mexico); Flores, C. [Instituto de Investigaciones en Materiales, Depto de Estado Solido, Laboratorio de Biomateriales, UNAM, Circuito Exterior C.U. S/N CP 04510 Mexico, D.F. (Mexico); Pina, C. [Instituto de Investigaciones en Materiales, Depto de Estado Solido, Laboratorio de Biomateriales, UNAM, Circuito Exterior C.U. S/N CP 04510 Mexico, D.F. (Mexico); Velazquez, R. [Centro de Fisica Aplicada Tecnologia Avanzada, UNAM, Km. 15 Carretera Queretaro-San Luis Potosi, C.P. 76230, Queretaro, Qro. (Mexico); Schaeffer, T.E. [Physikalisches Institut and Center for Nanotechnology, Universitaet Muenster, Gievenbecker Weg 11, 48149 Muenster (Germany); Bucio, L. [Instituto de Fisica, Depto de Estado Solido, UNAM, Circuito Exterior s/n, Ciudad Universitaria Apartado Postal 20-364 01000 Mexico D.F. (Mexico); Basiuk, V.A. [Instituto de Ciencias Nucleares, Departamento de Quimica de Radiaciones y Radioquimica, UNAM, Circuito Exterior C.U. Apdo., Postal 70-543, 04510 Mexico, D.F. (Mexico)

    2007-01-15

    White spots form in the brown shrimp (Penaeus aztecus, Decapoda) shell during frozen storage. The mineral formed consists of calcite incorporated into an amorphous {alpha}-chitin matrix. We studied mechanisms of interaction of amorphous {alpha}-chitin macromolecules with hkl crystal planes to form highly ordered structures, as well as the role of specific sites in the biopolymer, which can be related to nucleation and spheroidal crystal growth. We used low vacuum scanning electron microscopy (LVSEM), X-ray powder diffraction (XRD), atomic force microscopy (AFM), Fourier-transform infrared spectroscopy (FT-IR), and molecular mechanics modeling (MM+ method). AFM images showed fingerprint distances in the biopolymer and a highly layered structure in the crystalline material. The presence of {alpha}-chitin, with a specific spatial distribution of radicals, is thought to be responsible for nucleation and to thermodynamically stabilize ions to form the spherulite crystalline phase, which are usually oval to spherical (0.10 to 200 {mu}m in diameter). Our models of crystal-biopolymer interaction found high affinity of CO{sub 3} {sup 2-} anions in the (104) crystalline plane (the main plane in calcite monocrystals) to NH- groups of the biopolymer, as well as of the C=O in the biopolymer to Ca{sup 2+} cations in the crystalline structure. These interactions explain the spherical growth and inhibition in some planes. The specific physicochemical interactions (docking of groups depending on their geometrical distribution) suggest that the biomineral structure is controlled by the biopolymer on a local scale. This information is useful for further design and improvement of (hybrid) materials for versatile application, from nanotechnology to biomedicine and engineering.

  6. Effect of the STereoLithography file structure on the ear shell production for hearing aids according to DICOM images

    Energy Technology Data Exchange (ETDEWEB)

    KIm, Hyeong Gyun [Dept. of Radiological Science, Far East University, Eumseong (Korea, Republic of)

    2017-03-15

    A technique for producing the ear shell for a hearing aid using DICOM (Digital Imaging and Communication in Medicine) image and a 3D printing was studied. It is a new application method, and is an application technique that can improve the safety and infection of hearing aid users and can reduce the production time and process stages. In this study, the effects on the shape surface were examined before and after the printing of the ear shell using a 3D printer based on the values obtained from the raw data of the DICOM images at the volumes of 0.5 mm, 1.0 mm, and 2.0 mm, respectively. Before the printing, relative relationship was compared with respect to the STL (STereoLithography) file structure; and after the printing, the intervals of the layered structure of the ear shell shape surface were compared by magnifying them using a microscope. For the STL file structure, the numbers of triangular vertices, more than five intersecting points, and maximum intersecting points were large in the order of 0.5 mm, 1.0 m, and 2.0 mm, respectively; and the triangular structure was densely distributed in the order of the bending, angle, and crest regions depending on the sinuosity of the external auditory meatus shape. As for the ear shell shape surface examined by the digital microscope, the interval of the layered structure was thick in the order of 2.0 mm, 1.0 mm, and 0.5 mm. For the STL surface structure mentioned above, the intersecting STL triangular structure was denser as the sinuosity of the 3D ear shell shape became more irregular and the volume of the raw data decreased.

  7. Effect of the STereoLithography file structure on the ear shell production for hearing aids according to DICOM images

    International Nuclear Information System (INIS)

    KIm, Hyeong Gyun

    2017-01-01

    A technique for producing the ear shell for a hearing aid using DICOM (Digital Imaging and Communication in Medicine) image and a 3D printing was studied. It is a new application method, and is an application technique that can improve the safety and infection of hearing aid users and can reduce the production time and process stages. In this study, the effects on the shape surface were examined before and after the printing of the ear shell using a 3D printer based on the values obtained from the raw data of the DICOM images at the volumes of 0.5 mm, 1.0 mm, and 2.0 mm, respectively. Before the printing, relative relationship was compared with respect to the STL (STereoLithography) file structure; and after the printing, the intervals of the layered structure of the ear shell shape surface were compared by magnifying them using a microscope. For the STL file structure, the numbers of triangular vertices, more than five intersecting points, and maximum intersecting points were large in the order of 0.5 mm, 1.0 m, and 2.0 mm, respectively; and the triangular structure was densely distributed in the order of the bending, angle, and crest regions depending on the sinuosity of the external auditory meatus shape. As for the ear shell shape surface examined by the digital microscope, the interval of the layered structure was thick in the order of 2.0 mm, 1.0 mm, and 0.5 mm. For the STL surface structure mentioned above, the intersecting STL triangular structure was denser as the sinuosity of the 3D ear shell shape became more irregular and the volume of the raw data decreased

  8. Thick-target method in the measurement of inner-shell ionization cross-sections by low-energy electron impact

    International Nuclear Information System (INIS)

    An, Z.; Wu, Y.; Liu, M.T.; Duan, Y.M.; Tang, C.H.

    2006-01-01

    In this paper, we have studied the thick-target method for the measurements of atomic inner-shell ionization cross-section or X-ray production cross-section by keV electron impact. We find that in the processes of electron impact on the thick targets, the ratios of the characteristic X-ray yields of photoelectric ionization by bremsstrahlung to the total characteristic X-ray yields are Z-dependent and shell-dependent, and the ratios also show the weak energy-dependence. In addition, in the lower incident energy region (i.e. U < 5-6), the contribution from the rediffusion effect and the secondary electrons can be negligible. In general, the thick-target method can be appropriately applied to the measurements of atomic inner-shell ionization cross-sections or X-ray production cross-sections by electron impact for low and medium Z elements in the lower incident electron energy (i.e. U < 5-6). The experimental accuracies by the thick-target method can reach to the level equivalent or superior to the accuracies of experimental data based on the thin-target method. This thick-target method has been applied to the measurement of K-shell ionization cross-sections of Ni element by electron impact in this paper

  9. Correlated electronic structure of CeN

    Energy Technology Data Exchange (ETDEWEB)

    Panda, S.K., E-mail: swarup.panda@physics.uu.se [Department of Physics and Astronomy, Uppsala University, P.O. Box 516, SE-751 20 Uppsala (Sweden); Di Marco, I. [Department of Physics and Astronomy, Uppsala University, P.O. Box 516, SE-751 20 Uppsala (Sweden); Delin, A. [Department of Physics and Astronomy, Uppsala University, P.O. Box 516, SE-751 20 Uppsala (Sweden); KTH Royal Institute of Technology, School of Information and Communication Technology, Department of Materials and Nano Physics, Electrum 229, SE-164 40 Kista (Sweden); KTH Royal Institute of Technology, Swedish e-Science Research Center (SeRC), SE-100 44 Stockholm (Sweden); Eriksson, O., E-mail: olle.eriksson@physics.uu.se [Department of Physics and Astronomy, Uppsala University, P.O. Box 516, SE-751 20 Uppsala (Sweden)

    2016-04-15

    Highlights: • The electronic structure of CeN is studied within the GGA+DMFT approach using SPTF and Hubbard I approximation. • 4f spectral functions from SPTF and Hubbard I are coupled to explain the various spectroscopic manifestations of CeN. • The calculated XPS and BIS spectra show good agreement with the corresponding experimental spectra. • The contribution of the various l-states and the importance of cross-sections for the photoemission process are analyzed. - Abstract: We have studied in detail the electronic structure of CeN including spin orbit coupling (SOC) and electron–electron interaction, within the dynamical mean-field theory combined with density-functional theory in generalized gradient approximation (GGA+DMFT). The effective impurity problem has been solved through the spin-polarized T-matrix fluctuation-exchange (SPTF) solver and the Hubbard I approximation (HIA). The calculated l-projected atomic partial densities of states and the converged potential were used to obtain the X-ray-photoemission-spectra (XPS) and Bremstrahlung Isochromat spectra (BIS). Following the spirit of Gunnarsson–Schonhammer model, we have coupled the SPTF and HIA 4f spectral functions to explain the various spectroscopic manifestations of CeN. Our computed spectra in such a coupled scheme explain the experimental data remarkably well, establishing the validity of our theoretical model in analyzing the electronic structure of CeN. The contribution of the various l-states in the total spectra and the importance of cross sections are also analyzed in detail.

  10. Electronic structure theory of the superheavy elements

    Energy Technology Data Exchange (ETDEWEB)

    Eliav, Ephraim, E-mail: ephraim@tau.ac.il [School of Chemistry, Tel Aviv University, 6997801 Tel Aviv (Israel); Fritzsche, Stephan, E-mail: s.fritzsche@gsi.de [Helmholtz-Institut Jena, Fröbelstieg 3, D-07743 Jena (Germany); Theoretisch-Physikalisches Institut, Friedrich-Schiller-Universität Jena, D-07743 Jena (Germany); Kaldor, Uzi, E-mail: kaldor@tau.ac.il [School of Chemistry, Tel Aviv University, 6997801 Tel Aviv (Israel)

    2015-12-15

    High-accuracy calculations of atomic properties of the superheavy elements (SHE) up to element 122 are reviewed. The properties discussed include ionization potentials, electron affinities and excitation energies, which are associated with the spectroscopic and chemical behavior of these elements, and are therefore of considerable interest. Accurate predictions of these quantities require high-order inclusion of relativity and electron correlation, as well as large, converged basis sets. The Dirac–Coulomb–Breit Hamiltonian, which includes all terms up to second order in the fine-structure constant α, serves as the framework for the treatment; higher-order Lamb shift terms are considered in some selected cases. Electron correlation is treated by either the multiconfiguration self-consistent-field approach or by Fock-space coupled cluster theory. The latter is enhanced by the intermediate Hamiltonian scheme, allowing the use of larger model (P) spaces. The quality of the calculations is assessed by applying the same methods to lighter homologs of the SHEs and comparing with available experimental information. Very good agreement is obtained, within a few hundredths of an eV, and similar accuracy is expected for the SHEs. Many of the properties predicted for the SHEs differ significantly from what may be expected by straightforward extrapolation of lighter homologs, demonstrating that the structure and chemistry of SHEs are strongly affected by relativity. The major scientific challenge of the calculations is to find the electronic structure and basic atomic properties of the SHE and assign its proper place in the periodic table. Significant recent developments include joint experimental–computational studies of the excitation spectrum of Fm and the ionization energy of Lr, with excellent agreement of experiment and theory, auguring well for the future of research in the field.

  11. Spectral-Product Methods for Electronic Structure Calculations (Preprint)

    National Research Council Canada - National Science Library

    Langhoff, P. W; Mills, J. E; Boatz, J. A

    2006-01-01

    .... The spectral-product approach to molecular electronic structure avoids the repeated evaluations of the one- and two-electron integrals required in construction of polyatomic Hamiltonian matrices...

  12. Spectral-Product Methods for Electronic Structure Calculations (Postprint)

    National Research Council Canada - National Science Library

    Langhoff, P. W; Hinde, R. J; Mills, J. D; Boatz, J. A

    2007-01-01

    .... The spectral-product approach to molecular electronic structure avoids the repeated evaluations of the one- and two-electron integrals required in construction of polyatomic Hamiltonian matrices...

  13. In-medium no-core shell model for ab initio nuclear structure calculations

    International Nuclear Information System (INIS)

    Gebrerufael, Eskendr

    2017-01-01

    In this work, we merge two successful ab initio nuclear-structure methods, the no-core shell model (NCSM) and the multi-reference in-medium similarity renormalization group (IM-SRG), to define a novel many-body approach for the comprehensive description of ground and excited states of closed- and open-shell medium-mass nuclei. Building on the key advantages of the two methods - the decoupling of excitations at the many-body level in the IM-SRG, and the exact diagonalization in the NCSM applicable up to medium-light nuclei - their combination enables fully converged no-core calculations for an unprecedented range of nuclei and observables at moderate computational cost. The efficiency and rapid model-space convergence of the new approach make it ideally suited for ab initio studies of ground and low-lying excited states of nuclei up to the medium-mass regime. Interactions constructed within the framework of chiral effective field theory provide an excellent opportunity to describe properties of nuclei from first principles, i.e., rooted in quantum chromodynamics, they overcome the lack of predictive power of phenomenological potentials. The hard core of these interactions causes strong short-range correlations, which we soften by using the similarity-renormalization-group transformation that accelerates the model-space convergence of many-body calculations. Three-nucleon effects, which are mandatory for the correct description of bulk properties of nuclei, are included in our calculations by using the normal-ordered two-body approximation, which has been shown to be sufficient to capture the main effects of the three-nucleon interaction. Using these interactions, we analyze energies of ground and excited states in the carbon and oxygen isotopic chains, where conventional NCSM calculations are still feasible and provide an important benchmark. Furthermore, we study the Hoyle state in 12 C - a three-alpha cluster state that cannot be converged in standard NCSM

  14. Synthesis, structure and electronic structure of a new polymorph of CaGe2

    International Nuclear Information System (INIS)

    Tobash, Paul H.; Bobev, Svilen

    2007-01-01

    Reported are the flux synthesis, the crystal structure determination, the properties and the band structure calculations of a new polymorph of CaGe 2 , which crystallizes with the hexagonal space group P6 3 mc (no. 186) with cell parameters of a=3.9966(9) and c=10.211(4)A (Z=2; Pearson's code hP6). The structure can be viewed as puckered layers of three-bonded germanium atoms, ∼ 2 [Ge 2 ] 2- , which are stacked along the direction of the c-axis in an ABAB-fashion. The germanium polyanionic layers are separated by the Ca cations. As such, this structure is closely related to the structure of the other CaGe 2 polymorph, which crystallizes with the rhombohedral CaSi 2 type in the R3-bar m space group (No. 166), where the ∼ 2 [Ge 2 ] 2- layers are arranged in an AA'BB'CC'-fashion, and are also interspaced by Ca 2+ cations. LMTO calculations suggest that in spite of the formal closed-shell configuration for all atoms and the apparent adherence to the Zintl rules for electron counting, i.e., Ca 2+ [3b-Ge 1- ] 2 ), the phase will be a poor metal due to a small Ca-3d-Ge-4p band overlap. Magnetic susceptibility measurements as a function of the temperature indicate that the new CaGe 2 polymorph exhibits weak, temperature independent, Pauli-paramagnetism

  15. Core/Shell Structured TiO2/CdS Electrode to Enhance the Light Stability of Perovskite Solar Cells.

    Science.gov (United States)

    Hwang, Insung; Baek, Minki; Yong, Kijung

    2015-12-23

    In this work, enhanced light stability of perovskite solar cell (PSC) achieved by the introduction of a core/shell-structured CdS/TiO2 electrode and the related mechanism are reported. By a simple solution-based process (SILAR), a uniform CdS shell was coated onto the surface of a TiO2 layer, suppressing the activation of intrinsic trap sites originating from the oxygen vacancies of the TiO2 layer. As a result, the proposed CdS-PSC exhibited highly improved light stability, maintaining nearly 80% of the initial efficiency after 12 h of full sunlight illumination. From the X-ray diffraction analyses, it is suggested that the degradation of the efficiency of PSC during illumination occurs regardless of the decomposition of the perovskite absorber. Considering the light-soaking profiles of the encapsulated cells and the OCVD characteristics, it is likely that the CdS shell had efficiently suppressed the undesirable electron kinetics, such as trapping at the surface defects of the TiO2 and preventing the resultant charge losses by recombination. This study suggests that further complementary research on various effective methods for passivation of the TiO2 layer would be highly meaningful, leading to insight into the fabrication of PSCs stable to UV-light for a long time.

  16. Electronic structure and superconductivity of europium

    International Nuclear Information System (INIS)

    Nixon, Lane W.; Papaconstantopoulos, D.A.

    2010-01-01

    We have calculated the electronic structure of Eu for the bcc, hcp, and fcc crystal structures for volumes near equilibrium up to a calculated 90 GPa pressure using the augmented-plane-wave method in the local-density approximation. The frozen-core approximation was used with a semi-empirical shift of the f-states energies in the radial Schroedinger equation to move the occupied 4f valence states below the Γ 1 energy and into the core. This shift of the highly localized f-states yields the correct europium phase ordering with lattice parameters and bulk moduli in good agreement with experimental data. The calculated superconductivity properties under pressure for the bcc and hcp structures are also found to agree with and follow a T c trend similar to recent measurement by Debessai et al.

  17. Electromagnetic Radiation of Electrons in Periodic Structures

    CERN Document Server

    Potylitsyn, Alexander Petrovich

    2011-01-01

    Periodic magnetic structures (undulators) are widely used in accelerators to generate monochromatic undulator radiation (UR) in the range from far infrared to the hard X-ray region. Another periodic crystalline structure is used to produce quasimonochromatic polarized photon beams via the coherent bremsstrahlung mechanism (CBS). Due to such characteristics as monochromaticity, polarization and adjustability, these types of radiation is of large interest for applied and basic research of accelerator-emitted radiation. The book provides a detailed overview of the fundamental principles behind electromagnetic radiation emitted from accelerated charged particles (e.g. UR, CBS, radiation of fast electrons in Laser flash fields) as well as a unified description of relatively new radiation mechanisms which attracted great interest in recent years. This are the so-called polarization radiation excited by the Coulomb field of incident particles in periodic structures, parametric X-rays, resonant transition radiation a...

  18. Boson structure functions from inelastic electron scattering

    International Nuclear Information System (INIS)

    De Jager, C.W.

    1986-01-01

    The even /sup 104-110/Pd isotopes and /sup 196/Pt have been investigated at NIKHEF-K by high-resolution inelastic electron scattering. A new IBA-2 calculation has been performed for the Pd isotopes, in which the ratio of the proton and neutron coupling constants is taken from pion scattering. One set of boson structure functions sufficed for the description of the first and second E2-excitations in all Pd isotopes. The data showed no sensitivity for different structure functions for proton and neutron bosons. A preliminary analysis of a number of negative parity states (3/sup -/,5/sup -/ and 7/sup -/), observed in /sup 196/Pt, was performed through the introduction of an f-boson. The first E4-excitation in the palladium isotopes can be reasonably described with a β-structure function, but all other E4-excitations require the introduction of g-boson admixtures

  19. Photoelectron spectroscopy bulk and surface electronic structures

    CERN Document Server

    Suga, Shigemasa

    2014-01-01

    Photoelectron spectroscopy is now becoming more and more required to investigate electronic structures of various solid materials in the bulk, on surfaces as well as at buried interfaces. The energy resolution was much improved in the last decade down to 1 meV in the low photon energy region. Now this technique is available from a few eV up to 10 keV by use of lasers, electron cyclotron resonance lamps in addition to synchrotron radiation and X-ray tubes. High resolution angle resolved photoelectron spectroscopy (ARPES) is now widely applied to band mapping of materials. It attracts a wide attention from both fundamental science and material engineering. Studies of the dynamics of excited states are feasible by time of flight spectroscopy with fully utilizing the pulse structures of synchrotron radiation as well as lasers including the free electron lasers (FEL). Spin resolved studies also made dramatic progress by using higher efficiency spin detectors and two dimensional spin detectors. Polarization depend...

  20. Electronic Structures of LNA Phosphorothioate Oligonucleotides

    Directory of Open Access Journals (Sweden)

    Henrik G. Bohr

    2017-09-01

    Full Text Available Important oligonucleotides in anti-sense research have been investigated in silico and experimentally. This involves quantum mechanical (QM calculations and chromatography experiments on locked nucleic acid (LNA phosphorothioate (PS oligonucleotides. iso-potential electrostatic surfaces are essential in this study and have been calculated from the wave functions derived from the QM calculations that provide binding information and other properties of these molecules. The QM calculations give details of the electronic structures in terms of e.g., energy and bonding, which make them distinguish or differentiate between the individual PS diastereoisomers determined by the position of sulfur atoms. Rules are derived from the electronic calculations of these molecules and include the effects of the phosphorothioate chirality and formation of electrostatic potential surfaces. Physical and electrochemical descriptors of the PS oligonucleotides are compared to the experiments in which chiral states on these molecules can be distinguished. The calculations demonstrate that electronic structure, electrostatic potential, and topology are highly sensitive to single PS configuration changes and can give a lead to understanding the activity of the molecules. Keywords: LNA phosphorothioate, DNA/LNA oligonucleotide, diastereoisomers, Hartree-Fock calculations, iso-potential surface, anion chromatograms

  1. Nanospheres with a smectic hydrophobic core and an amorphous PEG hydrophilic shell: structural changes and implications for drug delivery

    Energy Technology Data Exchange (ETDEWEB)

    Murthy, N. Sanjeeva [New Jersey Center for Biomaterials; Rutgers; The State University of New Jersey; Piscataway; USA; Zhang, Zheng [New Jersey Center for Biomaterials; Rutgers; The State University of New Jersey; Piscataway; USA; Borsadia, Siddharth [New Jersey Center for Biomaterials; Rutgers; The State University of New Jersey; Piscataway; USA; Kohn, Joachim [New Jersey Center for Biomaterials; Rutgers; The State University of New Jersey; Piscataway; USA

    2018-01-01

    The structural changes in nanospheres with a crystalline core and an amorphous diffuse shell were investigated by small-angle neutron scattering (SANS), small-, medium-, and wide-angle X-ray scattering (SAXS, MAXS and WAXS), and differential scanning calorimetry (DSC).

  2. Rheological properties of magnetorheological suspensions based on core–shell structured polyaniline-coated carbonyl iron particles

    Czech Academy of Sciences Publication Activity Database

    Sedlačík, M.; Pavlínek, V.; Sáha, P.; Švrčinová, Petra; Filip, Petr; Stejskal, Jaroslav

    2010-01-01

    Roč. 19, č. 11 (2010), s. 115008 ISSN 0964-1726 R&D Projects: GA ČR GA202/09/1626 Institutional research plan: CEZ:AV0Z20600510; CEZ:AV0Z40500505 Keywords : magnetorheology * core - shell structure * polyaniline Subject RIV: BK - Fluid Dynamics Impact factor: 2.094, year: 2010

  3. Spin-spin interactions of electrons and also of nucleons create atomic molecular and nuclear structures

    International Nuclear Information System (INIS)

    Kaliambos, L.A.

    2008-01-01

    Fundamental interactions of spinning electrons at an interelectron separation less than 578.8 fm yield attractive electromagnetic forces with S = 0 creating vibrations under a motional emf. They explain the indistinguishability of electrons and give a vibration energy able for calculating the ground-state energies of many-electron atoms without using any perturbative approximation. Such forces create two-electron orbitals able to account for the exclusion principal and the mechanism of covalent bonds. In the outer subshells of atoms the penetrating orbitals interact also as pair-pair systems and deform drastically the probability densities of the quantum mechanical electron clouds. Such a dynamics of deformation removes the degeneracy and leads to the deviation from the shell scheme. However in the interior of atoms the large nuclear charge leads to a spherically symmetric potential with non-interacting pairs for creating shells of degenerate states giving an accurate explanation of the X-ray lines. On the other hand, considerable charge distributions in nucleons as multiples of 2e/3 and - e/3 determined by the magnetic moments, interact for creating the nuclear structure with p-n bonds. Such spin-spin interactions show that the dominant concept of the untisymmetric wave function for fermions is inapplicable not only in the simple p-n, p-p, and n-n systems but also in the LS coupling of atoms in which the electrons interact from different quantum states giving either S = 0 or S = l. (author)

  4. Energy storage in ferroelectric polymer nanocomposites filled with core-shell structured polymer@BaTiO3 nanoparticles: understanding the role of polymer shells in the interfacial regions.

    Science.gov (United States)

    Zhu, Ming; Huang, Xingyi; Yang, Ke; Zhai, Xing; Zhang, Jun; He, Jinliang; Jiang, Pingkai

    2014-11-26

    The interfacial region plays a critical role in determining the electrical properties and energy storage density of dielectric polymer nanocomposites. However, we still know a little about the effects of electrical properties of the interfacial regions on the electrical properties and energy storage of dielectric polymer nanocomposites. In this work, three types of core-shell structured polymer@BaTiO3 nanoparticles with polymer shells having different electrical properties were used as fillers to prepare ferroelectric polymer nanocomposites. All the polymer@BaTiO3 nanoparticles were prepared by surface-initiated reversible-addition-fragmentation chain transfer (RAFT) polymerization, and the polymer shells were controlled to have the same thickness. The morphology, crystal structure, frequency-dependent dielectric properties, breakdown strength, leakage currents, energy storage capability, and energy storage efficiency of the polymer nanocomposites were investigated. On the other hand, the pure polymers having the same molecular structure as the shells of polymer@BaTiO3 nanoparticles were also prepared by RAFT polymerization, and their electrical properties were provided. Our results show that, to achieve nanocomposites with high discharged energy density, the core-shell nanoparticle filler should simultaneously have high dielectric constant and low electrical conductivity. On the other hand, the breakdown strength of the polymer@BaTiO3-based nanocomposites is highly affected by the electrical properties of the polymer shells. It is believed that the electrical conductivity of the polymer shells should be as low as possible to achieve nanocomposites with high breakdown strength.

  5. Extraordinary electronic properties in uncommon structure types

    Science.gov (United States)

    Ali, Mazhar Nawaz

    In this thesis I present the results of explorations into several uncommon structure types. In Chapter 1 I go through the underlying idea of how we search for new compounds with exotic properties in solid state chemistry. The ideas of exploring uncommon structure types, building up from the simple to the complex, using chemical intuition and thinking by analogy are discussed. Also, the history and basic concepts of superconductivity, Dirac semimetals, and magnetoresistance are briefly reviewed. In chapter 2, the 1s-InTaS2 structural family is introduced along with the discovery of a new member of the family, Ag0:79VS2; the synthesis, structure, and physical properties of two different polymorphs of the material are detailed. Also in this chapter, we report the observation of superconductivity in another 1s structure, PbTaSe2. This material is especially interesting due to it being very heavy (resulting in very strong spin orbit coulping (SOC)), layered, and noncentrosymmetric. Electronic structure calculations reveal the presence of a bulk 3D Dirac cone (very similar to graphene) that is gapped by SOC originating from the hexagonal Pb layer. In Chapter 3 we show the re-investigation of the crystal structure of the 3D Dirac semimetal, Cd3As2. It is found to be centrosymmetric, rather than noncentrosymmetric, and as such all bands are spin degenerate and there is a 4-fold degenerate bulk Dirac point at the Fermi level, making Cd3As2 a 3D electronic analog to graphene. Also, for the first time, scanning tunneling microscopy experiments identify a 2x2 surface reconstruction in what we identify as the (112) cleavage plane of single crystals; needle crystals grow with a [110] long axis direction. Lastly, in chapter 4 we report the discovery of "titanic" (sadly dubbed ⪉rge, nonsaturating" by Nature editors and given the acronym XMR) magnetoresistance (MR) in the non-magnetic, noncentrosymmetric, layered transition metal dichalcogenide WTe2; over 13 million% at 0.53 K in

  6. Projected quasiparticle theory for molecular electronic structure

    Science.gov (United States)

    Scuseria, Gustavo E.; Jiménez-Hoyos, Carlos A.; Henderson, Thomas M.; Samanta, Kousik; Ellis, Jason K.

    2011-09-01

    We derive and implement symmetry-projected Hartree-Fock-Bogoliubov (HFB) equations and apply them to the molecular electronic structure problem. All symmetries (particle number, spin, spatial, and complex conjugation) are deliberately broken and restored in a self-consistent variation-after-projection approach. We show that the resulting method yields a comprehensive black-box treatment of static correlations with effective one-electron (mean-field) computational cost. The ensuing wave function is of multireference character and permeates the entire Hilbert space of the problem. The energy expression is different from regular HFB theory but remains a functional of an independent quasiparticle density matrix. All reduced density matrices are expressible as an integration of transition density matrices over a gauge grid. We present several proof-of-principle examples demonstrating the compelling power of projected quasiparticle theory for quantum chemistry.

  7. Influence of changes in the valence electronic configuration on the structure of L-X-ray spectra of molybdenum

    International Nuclear Information System (INIS)

    Polasik, M; Koziol, K; Slabkowska, K; Czarnota, M; Pajek, M

    2009-01-01

    Extensive multiconfiguration Dirac-Fock (MCDF) calculations with the inclusion of the transverse (Breit) interaction and QED corrections have been carried out on molybdenum to explain the dependence of the structure of Lα 1,2 and Lβ 1 lines on the changes in configurations of the valence electrons belonging to two different configuration types: three open-shell 4d 6-r 5s r (r = 2,1,0) configurations and one closed-shell 4d 4 3/2 5s 2 configuration. It has been found that the MCDF predictions for open-shell valence configurations (4d 4 5s 2 , 4d 5 5s 1 , 4d 6 5s 0 ) much better reproduce observed structure of Lα 1,2 lines in X-ray spectra of molybdenum than closed-shell 4d 4 3/2 5s 2 valence configuration. The influence of changes in the valence electronic configuration on the structure of L-X-ray spectra of molybdenum is noticeable. Moreover, the observation of the shapes of L-X-ray spectra seems to be very good method to investigate the changes of the valence electronic configuration caused by the chemical environment.

  8. Shell Venster

    International Nuclear Information System (INIS)

    De Wit, P.; Looijesteijn, B.; Regeer, B.; Stip, B.

    1995-03-01

    In the bi-monthly issues of 'Shell Venster' (window on Shell) attention is paid to the activities of the multinational petroleum company Shell Nederland and the Koninklijke/Shell Groep by means of non-specialist articles

  9. Direct observation and analysis of york-shell materials using low-voltage high-resolution scanning electron microscopy: Nanometal-particles encapsulated in metal-oxide, carbon, and polymer

    Directory of Open Access Journals (Sweden)

    Shunsuke Asahina

    2014-11-01

    Full Text Available Nanometal particles show characteristic features in chemical and physical properties depending on their sizes and shapes. For keeping and further enhancing their features, the particles should be protected from coalescence or degradation. One approach is to encapsulate the nanometal particles inside pores with chemically inert or functional materials, such as carbon, polymer, and metal oxides, which contain mesopores to allow permeation of only chemicals not the nanometal particles. Recently developed low-voltage high-resolution scanning electron microscopy was applied to the study of structural, chemical, and electron state of both nanometal particles and encapsulating materials in york-shell materials of Au@C, Ru/Pt@C, Au@TiO2, and Pt@Polymer. Progresses in the following categories were shown for the york-shell materials: (i resolution of topographic image contrast by secondary electrons, of atomic-number contrast by back-scattered electrons, and of elemental mapping by X-ray energy dispersive spectroscopy; (ii sample preparation for observing internal structures; and (iii X-ray spectroscopy such as soft X-ray emission spectroscopy. Transmission electron microscopy was also used for characterization of Au@C.

  10. Direct observation and analysis of yolk-shell materials using low-voltage high-resolution scanning electron microscopy: Nanometal-particles encapsulated in metal-oxide, carbon, and polymer

    Energy Technology Data Exchange (ETDEWEB)

    Asahina, Shunsuke; Suga, Mitsuo; Takahashi, Hideyuki [JEOL Ltd., SM Business Unit, Tokyo (Japan); Young Jeong, Hu [Graduate School of EEWS, WCU/BK21+, KAIST, Daejeon 305-701 (Korea, Republic of); Galeano, Carolina; Schüth, Ferdi [Department of Heterogeneous Catalysis, Max-Planck-Institut für Kohlenforschung, Mülheim (Germany); Terasaki, Osamu, E-mail: terasaki@mmk.su.se, E-mail: terasaki@kaist.ac.kr [Graduate School of EEWS, WCU/BK21+, KAIST, Daejeon 305-701 (Korea, Republic of); Department of Materials and Environmental Chemistry, Berzelii Centre EXSELENT on Porous Materials, Stockholm University, SE-10691 Stockholm (Sweden)

    2014-11-01

    Nanometal particles show characteristic features in chemical and physical properties depending on their sizes and shapes. For keeping and further enhancing their features, the particles should be protected from coalescence or degradation. One approach is to encapsulate the nanometal particles inside pores with chemically inert or functional materials, such as carbon, polymer, and metal oxides, which contain mesopores to allow permeation of only chemicals not the nanometal particles. Recently developed low-voltage high-resolution scanning electron microscopy was applied to the study of structural, chemical, and electron state of both nanometal particles and encapsulating materials in yolk-shell materials of Au@C, Ru/Pt@C, Au@TiO{sub 2}, and Pt@Polymer. Progresses in the following categories were shown for the yolk-shell materials: (i) resolution of topographic image contrast by secondary electrons, of atomic-number contrast by back-scattered electrons, and of elemental mapping by X-ray energy dispersive spectroscopy; (ii) sample preparation for observing internal structures; and (iii) X-ray spectroscopy such as soft X-ray emission spectroscopy. Transmission electron microscopy was also used for characterization of Au@C.

  11. Preliminary structural investigations of the Eut-L shell protein of the ethanolamine ammonia-lyase metabolosome of Escherichia coli

    International Nuclear Information System (INIS)

    Nikolakakis, Kiel; Ohtaki, Akashi; Newton, Keith; Chworos, Arkadiusz; Sagermann, Martin

    2009-01-01

    Preliminary X-ray analysis of crystals of the bacterial microcompartment shell protein Eut-L from Escherichia coli is reported. The ethanolamine ammonia-lyase microcompartment is composed of five different shell proteins that have been proposed to assemble into symmetrically shaped polyhedral particles of varying sizes. Here, preliminary X-ray analysis of crystals of the bacterial microcompartment shell protein Eut-L from Escherichia coli is reported. Cloning, overexpression and purification resulted in highly pure protein that crystallized readily under many different conditions. In all cases the protein forms thin hexagonal plate-shaped crystals belonging to space group P3 that are of unusually high stability against different solvent conditions. The crystals diffracted to a resolution of 2.0 Å using synchrotron radiation but proved to be radiation-sensitive. Preparations of heavy-atom-derivatized crystals for use in determining the three-dimensional structure are under way

  12. Inferring Enceladus' ice shell strength and structure from Tiger Stripe formation

    Science.gov (United States)

    Rhoden, A.; Hurford, T., Jr.; Spitale, J.; Henning, W. G.

    2017-12-01

    The tiger stripe fractures (TSFs) of Enceladus are four, roughly parallel, linear fractures that correlate with plume sources and high heat flows measured by Cassini. Diurnal variations of plume eruptions along the TSFs strongly suggest that tides modulate the eruptions. Several attempts have been made to infer Enceladus' ice shell structure, and the mechanical process of plume formation, by matching variations in the plumes' eruptive output with tidal stresses for different interior models. Unfortunately, the many, often degenerate, unknowns make these analyses non-unique. Tidal-interior models that best match the observed plume variability imply very low tidal stresses (<14 kPa), much lower than the 1 MPa tensile strength of ice implied by lab experiments or the 100 kPa threshold inferred for Europa's ice. In addition, the interior models that give the best matches are inconsistent with the constraints from observed librations. To gain more insight into the interior structure and rheology of Enceladus and the role of tidal stress in the development of the south polar terrain, we utilize the orientations of the TSFs themselves as observational constraints on tidal-interior models. While the initial formation of the TSFs has previously been attributed to tidal stress, detailed modeling of their formation has not been performed until now. We compute tidal stresses for a suite of rheologically-layered interior models, consistent with Enceladus' observed librations, and apply a variety of failure conditions. We then compare the measured orientations at 6391 points along the TSFs with the predicted orientations from the tidal models. Ultimately, we compute the likelihood of forming the TSFs with tidal stresses for each model and failure condition. We find that tidal stresses are a good match to the observed orientations of the TSFs and likely led to their formation. We also find that the model with the highest likelihood changes depending on the failure criterion

  13. Electronic structure of defects in semiconductor heterojunctions

    International Nuclear Information System (INIS)

    Haussy, Bernard; Ganghoffer, Jean Francois

    2002-01-01

    Full text.heterojunctions and semiconductors and superlattices are well known and well used by people interested in optoelectronics communications. Components based on the use of heterojunctions are interesting for confinement of light and increase of quantum efficiency. An heterojunction is the contact zone between two different semiconductors, for example GaAs and Ga 1-x Al x As. Superlattices are a succession of heterojunctions (up to 10 or 20). These systems have been the subjects of many experiments ao analyse the contact between semiconductors. They also have been theoretically studied by different types of approach. The main result of those studies is the prediciton of band discontinuities. Defects in heterojunctions are real traps for charge carriers; they can affect the efficiency of the component decreasing the currents and the fluxes in it. the knowledge of their electronic structure is important, a great density of defects deeply modifies the electronic structure of the whole material creating real new bands of energy in the band structure of the component. in the first part of this work, we will describe the heterostructure and the defect in terms of quantum wells and discrete levels. This approach allows us to show the role of the width of the quantum well describing the structure but induces specific behaviours due to the one dimensional modelling. Then a perturbative treatment is proposed using the Green's functions formalism. We build atomic chains with different types of atoms featuring the heterostructure and the defect. Densities of states of a structure with a defect and levels associated to the defect are obtained. Results are comparable with the free electrons work, but the modelling do not induce problems due to a one dimensional approach. To extend our modelling, a three dimensions approach, based on a cavity model, is investigated. The influence of the defect, - of hydrogenoid type - introduced in the structure, is described by a cavity

  14. Atomic Reference Data for Electronic Structure Calculations

    CERN Document Server

    Kotochigova, S; Shirley, E L

    We have generated data for atomic electronic structure calculations, to provide a standard reference for results of specified accuracy under commonly used approximations. Results are presented here for total energies and orbital energy eigenvalues for all atoms from H to U, at microHartree accuracy in the total energy, as computed in the local-density approximation (LDA) the local-spin-density approximation (LSD); the relativistic local-density approximation (RLDA); and scalar-relativistic local-density approximation (ScRLDA).

  15. The electronic structure of impurities in semiconductors

    CERN Multimedia

    Nylandsted larsen, A; Svane, A

    2002-01-01

    The electronic structure of isolated substitutional or interstitial impurities in group IV, IV-IV, and III-V compound semiconductors will be studied. Mössbauer spectroscopy will be used to investigate the incorporation of the implanted isotopes on the proper lattice sites. The data can be directly compared to theoretical calculations using the LMTO scheme. Deep level transient spectroscopy will be used to identify the band gap levels introduced by metallic impurities, mainly in Si~and~Si$ _{x}$Ge$_{1-x}$. \\\\ \\\\

  16. Unoccupied surface electronic structure of Gd(0001)

    International Nuclear Information System (INIS)

    Li, D.; Dowben, P.A.; Ortega, J.E.; Himpsel, F.J.

    1994-01-01

    The unoccupied surface electronic structure of Gd(0001) was investigated with high-resolution inverse-photoemission spectroscopy. An empty surface state near E F is observed at bar Γ. Two other surface-sensitive features are also revealed at 1.2 and 3.1 eV above the Fermi level. Hydrogen adsorption on Gd surfaces was used to distinguish the surface-sensitive features from the bulk features. The unoccupied bulk-band critical points are determined to be Γ 3 + at 1.9 eV and A 1 at 0.8 eV

  17. Cobalamins uncovered by modern electronic structure calculations

    DEFF Research Database (Denmark)

    Kepp, Kasper Planeta; Ryde, Ulf

    2009-01-01

    electronic-structure calculations, in particular density functional methods, the understanding of the molecular mechanism of cobalamins has changed dramatically, going from a dominating view of trans-steric strain effects to a much more complex view involving an arsenal of catalytic strategies. Among...... these are cis-steric distortions, electrostatic stabilization of radical products, the realization that nucleotide units can serve as polar handles, and the careful design of the active sites, with polar residues in the radical enzymes and non-polar residues in the transferases. Together, these strategies...

  18. Electronic golden structure of the periodic chart

    Energy Technology Data Exchange (ETDEWEB)

    Malinowski, Leonard J. [Interdisciplinary Research Club, Monroeville, PA (United States)], E-mail: LJMalinowski@gmail.com

    2009-11-15

    The golden ratio has been studied since the ancient Greeks due to its inherent symmetry and aesthetic beauty, especially in the five Platonic Solids. The golden mean is now established as a pillar of El Naschie's E infinity where it achieves the physical manifestation of 0.618 034 MeV. The largest atomic electron orbital total energies average to the golden mean energy. This paper examines the golden ratio in order to expand upon a century old attempt to produce a relatively static, visual, geometric model of atomic structure.

  19. Electronic golden structure of the periodic chart

    International Nuclear Information System (INIS)

    Malinowski, Leonard J.

    2009-01-01

    The golden ratio has been studied since the ancient Greeks due to its inherent symmetry and aesthetic beauty, especially in the five Platonic Solids. The golden mean is now established as a pillar of El Naschie's E infinity where it achieves the physical manifestation of 0.618 034 MeV. The largest atomic electron orbital total energies average to the golden mean energy. This paper examines the golden ratio in order to expand upon a century old attempt to produce a relatively static, visual, geometric model of atomic structure.

  20. Electronic structure of A15 compounds

    International Nuclear Information System (INIS)

    Pickett, W.E.

    1980-01-01

    For the past twenty-five years compounds with the A15 crystal structure have dominated the class of high temperature superconductors. The crystal structure of an A15 compound A 3 B is cubic (space group O/sub h/ 3 ). However, the site symmetry (D/sub 2d/) of the A atoms is much lower than cubic, an unusual occurrence in cubic binary compounds. Variations on this theme have supplied the basis of many theoretical models of the anomalous temperature (T) dependence of normal state properties and the low temperature cubic reversible tetragonal structural transformations which accompany high values of T/sub c/ in A15 compounds. In this paper results of self-consistent pseudopotential band structure calculations are used to assess some important aspects of the unique and unusual behavior in A15 compounds: (1) the role of the B atom in determining the overall electronic structure will be shown to be important; (2) the effect of the low site symmetry of the A atom on the charge density and potential will be assessed; and (3) the bonding will be shown to be metallic-covalent with no significant A-B charge transfer

  1. Electronic structure of point defects in semiconductors

    International Nuclear Information System (INIS)

    Bruneval, Fabien

    2014-01-01

    This 'Habilitation a diriger des Recherches' memoir presents most of my scientific activities during the past 7 years, in the field of electronic structure calculations of defects in solids. Point defects (vacancies, interstitials, impurities) in functional materials are a key parameter to determine if these materials will actually fill the role they have been assigned or not. Indeed, the presence of defects cannot be avoided when the temperature is increased or when the material is subjected to external stresses, such as irradiation in the nuclear reactors and in artificial satellites with solar radiations. However, in many cases, defects are introduced in the materials on purpose to tune the electronic transport, optical or even magnetic properties. This procedure is called the doping of semiconductors, which is the foundation technique for transistors, diodes, or photovoltaic cells. However, doping is not always straightforward and unexpected features may occur, such as doping asymmetry or Fermi level pinning, which can only be explained by complex phenomena involving different types of defects or complexes of defects. In this context, the calculations of electronic structure ab initio is an ideal tool to complement the experimental observations, to gain the understanding of phenomena at the atomic level, and even to predict the properties of defects. The power of the ab initio calculations comes from their ability to describe any system of electrons and nuclei without any specific adjustment. But although there is a strong need for numerical simulations in this field, the ab initio calculations for defects are still under development as of today. The work presented in this memoir summarizes my contributions to methodological developments on this subject. These developments have followed two main tracks. The first topic is the better understanding of the unavoidable finite size effects. Indeed, defects in semiconductors or insulators are generally present in

  2. Core-shell structural nanodiamond@TiN supported Pt nanoparticles as a highly efficient and stable electrocatalyst for direct methanol fuel cells

    International Nuclear Information System (INIS)

    Zhao, Yuling; Wang, Yanhui; Dong, Liang; Zhang, Yan; Huang, Junjie; Zang, Jianbing; Lu, Jing; Xu, Xipeng

    2014-01-01

    Highlights: • Core-shell structural nanodiamond@TiN was used as a novel support for Pt catalysts. • The ND@TiN support possessed a high electrochemical stability than carbon black. • The Pt/ND@TiN showed a higher catalytic activity for MOR and ORR than the Pt/C. • The Pt/ND@TiN demonstrated a much better durability compared with the Pt/C. - Abstract: A novel core-shell support material was designed with nanodiamond (ND) as core possessed excellent stability and TiN as shell improved the conductivity of support. The nano-TiN shell was decorated on the surface of ND by annealing TiO 2 in nitrogen atmosphere, and the obtained ND@TiN was employed to support Pt nanoparticles (NPs). The ND@TiN support and Pt/ND@TiN electrocatalyst were characterized by X-ray diffraction and transmission electron microscopy. ND particles were coated uniformly by the TiN layer and Pt NPs with a mean size of 4.2 nm were highly dispersed on the surface of ND@TiN. The electrochemical results confirmed that the ND@TiN support possessed a much more stability than the carbon black and exhibited a bigger background current density than the ND. The Pt/ND@TiN catalyst showed higher catalytic activity and better stability in methanol oxidation and oxygen reduction reactions compared with the Pt/C and Pt/ND

  3. Core-Shell Double Gyroid Structure Formed by Linear ABC Terpolymer Thin Films.

    Science.gov (United States)

    Antoine, Ségolène; Aissou, Karim; Mumtaz, Muhammad; Telitel, Siham; Pécastaings, Gilles; Wirotius, Anne-Laure; Brochon, Cyril; Cloutet, Eric; Fleury, Guillaume; Hadziioannou, Georges

    2018-05-01

    The synthesis and self-assembly in thin-film configuration of linear ABC triblock terpolymer chains consisting of polystyrene (PS), poly(2-vinylpyridine) (P2VP), and polyisoprene (PI) are described. For that purpose, a hydroxyl-terminated PS-b-P2VP (45 kg mol -1 ) building block and a carboxyl-terminated PI (9 kg mol -1 ) are first separately prepared by anionic polymerization, and then are coupled via a Steglich esterification reaction. This quantitative and metal-free catalyst synthesis route reveals to be very interesting since functionalization and purification steps are straightforward, and well-defined terpolymers are produced. A solvent vapor annealing (SVA) process is used to promote the self-assembly of frustrated PS-b-P2VP-b-PI chains into a thin-film core-shell double gyroid (Q 230 , space group: Ia3¯d) structure. As terraces are formed within PS-b-P2VP-b-PI thin films during the SVA process under a CHCl 3 vapor, different plane orientations of the Q 230 structure ((211), (110), (111), and (100)) are observed at the polymer-air interface depending on the film thickness. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Electronic structure of hcp transition metals

    DEFF Research Database (Denmark)

    Jepsen, O.; Andersen, O. Krogh; Mackintosh, A. R.

    1975-01-01

    Using the linear muffin-tin-orbital method described in the previous paper, we have calculated the electronic structures of the hcp transition metals, Zr, Hf, Ru, and Os. We show how the band structures of these metals may be synthesized from the sp and d bands, and illustrate the effects...... of hybridization, relativistic band shifts, and spin-orbit coupling by the example of Os. By making use of parameters derived from the muffin-tin potential, we discuss trends in the positions and widths of the energy bands, especially the d bands, as a function of the location in the periodic table. The densities...... of states of the four metals are presented, and the calculated heat capacities compared with experiment. The Fermi surfaces of both Ru and Os are found to be in excellent quantitative agreement with de Haas-van Alphen measurements, indicating that the calculated d-band position is misplaced by less than 10...

  5. A novel platform of hemoglobin on core-shell structurally Fe{sub 3}O{sub 4}-Au nanoparticles and its direct electrochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Liu Yang; Han Ting; Chen Chao; Bao Ning; Yu Chunmei [Institute of Analytical Chemistry for Life Science, School of Public Health, Nantong University, Nantong 226019 (China); Gu Haiying, E-mail: hygu@ntu.edu.c [Institute of Analytical Chemistry for Life Science, School of Public Health, Nantong University, Nantong 226019 (China)

    2011-03-30

    Research highlights: {yields} In recent years, immobilization of biomolecule onto nanomaterials, which could be utilized in the investigation of biomolecule reactions and the preparations of the biosensors, has attracted much research attention. A novel platform, which hemoglobin (Hb) was immobilized on core-shell structurally Fe{sub 3}O{sub 4}/Au nanoparticles (simplified as Fe{sub 3}O{sub 4}-Au NPs) modified glassy carbon electrode (GCE), has been developed for fabricating the third biosensors in this paper. {yields} Magnetic NPs stand out because of their added properties. However, naked Fe{sub 3}O{sub 4} NPs are very sensitive to oxidation because of their high chemical reactivity and being prone to aggregate. Those defects limit their further applications. We presented a simple approach to synthesize Au modified Fe{sub 3}O{sub 4} NPs with core-shell structure, which was characterized by transmission electron microscopy, scanning electron microscope, energy dispersive spectra and UV-vis spectroscopy. {yields} The thermodynamics, dynamics and catalysis properties of Hb immobilized on Fe{sub 3}O{sub 4}-Au NPs were discussed by UV-visible spectrum, electrochemical impedance spectroscopy, electrochemical quartz crystal microbalance technique and cyclic voltammetry. The electrocatalytic behaviors of the immobilized Hb on Fe{sub 3}O{sub 4}-Au NPs were applied for the determination of hydrogen peroxide, oxygen and trichloroacetic acid. The possible functions of Fe{sub 3}O{sub 4} core and Au shell as a novel platform for achieving Hb direct electrochemistry were also discussed, respectively. - Abstract: A novel platform, which hemoglobin (Hb) was immobilized on core-shell structurally Fe{sub 3}O{sub 4}/Au nanoparticles (simplified as Fe{sub 3}O{sub 4}-Au NPs) modified glassy carbon electrode (GCE), has been developed for fabricating the third biosensors. Fe{sub 3}O{sub 4}-Au NPs, characterized using transmission electron microscope (TEM), scanning electron microscope

  6. Experimental Benchmarking of Pu Electronic Structure

    International Nuclear Information System (INIS)

    Tobin, J.G.; Moore, K.T.; Chung, B.W.; Wall, M.A.; Schwartz, A.J.; Ebbinghaus, B.B.; Butterfield, M.T.; Teslich, N.E. Jr.; Bliss, R.A.; Morton, S.A.; Yu, S.W.; Komesu, T.; Waddill, G.D.; van der Laan, G.; Kutepov, A.L.

    2008-01-01

    The standard method to determine the band structure of a condensed phase material is to (1) obtain a single crystal with a well defined surface and (2) map the bands with angle resolved photoelectron spectroscopy (occupied or valence bands) and inverse photoelectron spectroscopy (unoccupied or conduction bands). Unfortunately, in the case of Pu, the single crystals of Pu are either nonexistent, very small and/or having poorly defined surfaces. Furthermore, effects such as electron correlation and a large spin-orbit splitting in the 5f states have further complicated the situation. Thus, we have embarked upon the utilization of unorthodox electron spectroscopies, to circumvent the problems caused by the absence of large single crystals of Pu with well-defined surfaces. Our approach includes the techniques of resonant photoelectron spectroscopy, x-ray absorption spectroscopy, electron energy loss spectroscopy, Fano Effect measurements, and Bremstrahlung Isochromat Spectroscopy, including the utilization of micro-focused beams to probe single-crystallite regions of polycrystalline Pu samples.

  7. Deep learning and the electronic structure problem

    Science.gov (United States)

    Mills, Kyle; Spanner, Michael; Tamblyn, Isaac

    In the past decade, the fields of artificial intelligence and computer vision have progressed remarkably. Supported by the enthusiasm of large tech companies, as well as significant hardware advances and the utilization of graphical processing units to accelerate computations, deep neural networks (DNN) are gaining momentum as a robust choice for many diverse machine learning applications. We have demonstrated the ability of a DNN to solve a quantum mechanical eigenvalue equation directly, without the need to compute a wavefunction, and without knowledge of the underlying physics. We have trained a convolutional neural network to predict the total energy of an electron in a confining, 2-dimensional electrostatic potential. We numerically solved the one-electron Schrödinger equation for millions of electrostatic potentials, and used this as training data for our neural network. Four classes of potentials were assessed: the canonical cases of the harmonic oscillator and infinite well, and two types of randomly generated potentials for which no analytic solution is known. We compare the performance of the neural network and consider how these results could lead to future advances in electronic structure theory.

  8. Strain Measurement of Steel Roof Truss Using FBG Sensor during Construction of Reverse Shell Shaped Reinforced Concrete Structure

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kun Woo [Kyungpook National University, Daegu (Korea, Republic of); Rhim, Hong Chul; Seo, Tae Seok [Yonsei University, Seoul (Korea, Republic of)

    2011-08-15

    Application of FBG (Fiber Bragg Grating) sensors to measure strain of steel roof trusses has been performed. This is to check and confirm the structural integrity of an unusually shaped, reverse shell structure made of reinforced concrete. The issue was to place sensors at proper location and compare the measured values to the results from structural analysis. It has been learned that a deliberate measurement scheme is needed in order to monitor a complex structure during construction. In this study, the measured values were within allowable range of strain, thus confirming the safety of the structure during measurement and construction.

  9. Immobilization of cholesterol oxidase on magnetic fluorescent core-shell-structured nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Jun, E-mail: hjun@whut.edu.cn; Liu, Huichao; Zhang, Peipei; Zhang, Pengfei; Li, Mengshi; Ding, Liyun

    2015-12-01

    The magnetic fluorescent core-shell structured nanoparticles, Fe{sub 3}O{sub 4}@SiO{sub 2}(F)@meso–SiO{sub 2} nanoparticles, were prepared. Cholesterol oxidase (COD) was immobilized on their surface to form Fe{sub 3}O{sub 4}@SiO{sub 2}(F)@meso–SiO{sub 2}@COD nanoparticles. Optimal immobilization was achieved with 2.5% (v/v) APTES, 2.0% (v/v) GA, 10 mg COD (in 15 mg carrier) and solution pH of 7.0. Fe{sub 3}O{sub 4}@SiO{sub 2}(F)@meso–SiO{sub 2}@COD nanoparticles showed maximal catalytic activity at pH 7.0 and 50 °C. The thermal, storage and operational stabilities of COD were improved greatly after its immobilization. After the incubation at 50 °C for 5 h, the nanoparticles and free COD retained 80% and 46% of its initial activity, respectively. After kept at 4 °C for 30 days, the nanoparticles and free COD maintained 86% and 65% of initial activity, respectively. The nanoparticles retained 71% of its initial activity after 7 consecutive operations. Since Fe{sub 3}O{sub 4}@SiO{sub 2}(F)@meso–SiO{sub 2}@COD nanoparticles contained tris(2,2-bipyridyl)dichloro-ruthenium(II) hexahydrate (Ru(bpy){sub 3}Cl{sub 2}) and were optical sensitive to oxygen in solution, it might be used as the sensing material and has the application potential in multi parameter fiber optic biosensor based on enzyme catalysis and oxygen consumption. - Highlights: • COD was immobilized on magnetic fluorescent core-shell structured nanoparticles. • The nanoparticles were optical sensitive to oxygen in water solution. • The nanoparticles have remarkable improved stability compared with free COD. • The nanoparticles can probably be used in multi parameter fiber optic Biosensor.

  10. Structure and navigation for electronic publishing

    Science.gov (United States)

    Tillinghast, John; Beretta, Giordano B.

    1998-01-01

    The sudden explosion of the World Wide Web as a new publication medium has given a dramatic boost to the electronic publishing industry, which previously was a limited market centered around CD-ROMs and on-line databases. While the phenomenon has parallels to the advent of the tabloid press in the middle of last century, the electronic nature of the medium brings with it the typical characteristic of 4th wave media, namely the acceleration in its propagation speed and the volume of information. Consequently, e-publications are even flatter than print media; Shakespeare's Romeo and Juliet share the same computer screen with a home-made plagiarized copy of Deep Throat. The most touted tool for locating useful information on the World Wide Web is the search engine. However, due to the medium's flatness, sought information is drowned in a sea of useless information. A better solution is to build tools that allow authors to structure information so that it can easily be navigated. We experimented with the use of ontologies as a tool to formulate structures for information about a specific topic, so that related concepts are placed in adjacent locations and can easily be navigated using simple and ergonomic user models. We describe our effort in building a World Wide Web based photo album that is shared among a small network of people.

  11. Electronic structure and superconductivity of fcc Cr

    International Nuclear Information System (INIS)

    Xu, J.; Freeman, A.J.; Jarlborg, T.; Brodsky, M.B.

    1984-01-01

    Results of self-consistent electronic structure calculations are reported for metastable fcc Cr metal. Unlike the case of bcc Cr which has E/sub F/ at a minimum in the density of states (DOS), the DOS at E/sub F/ in fcc Cr is at a peak making this one of the higher-DOS metals with the fcc structure (e.g., comparable with that of Ni and Pt). A calculated Stoner factor of 0.82 indicates that ferromagnetic ordering is not expected. Calculations of the electron-phonon coupling parameter lambda and superconducting transition temperature T/sub c/ were made using the rigid-ion approximation and strong-coupling theory with various estimates of the (unknown) phonon contribution. We conclude that T/sub c/'sroughly-equal2.5 K are reasonable, although they are substantially smaller than the T/sub c/roughly-equal10 K derived from measurements on Au-Cr-Au sandwiches

  12. Structure of X-ray photoelectron spectra of low-energy and core electrons of Ln(C6H4OCH3COO-3

    Directory of Open Access Journals (Sweden)

    Teterin Yury A.

    2005-01-01

    Full Text Available This paper deals with the results of an X-ray photo electron spectroscopy of lanthanide ortho-metoxybenzoates Ln(C6H4OCH3COO-3, where Ln represents lanthanides La through Lu except for Pm and C6H4OCH3COO- - residuum of ortho-metoxybenzoic acid. The core and outer electron X-ray photo electron spectroscopy spectra in the binding energy range of 0-1250 eV were shown to exhibit a complex, fine structure. The said structure was established due to the outer (0-15 eV binding energy and inner (15-50 eV binding energy valence molecular orbital from the filled Ln5p and O2s atomic shells multiple splitting, many-body perturbation, dynamic effect, etc. The mechanisms of such a fine structure formation were shown to manifest different probabilities in the spectrum of a certain electronic shell. There fore, the fine X-ray photo electron spectroscopy spectral structure resulting from a certain mechanism can be interpreted and its quantitative parameters related to the physical and chemical properties of the studied com pounds (degree of delocalization and participation of Ln4f electrons in the chemical bond, electronic configuration and oxidation states, density of uncoupled electrons on paramagnetic ions, degree of participation of the low binding energy filled electronic shells of lanthanide and ligands information of the outer and in nervalence molecular orbitals, lanthanide close environment structure in amorphous materials, etc.

  13. Electronic structure of Ca, Sr, and Ba under pressure.

    Science.gov (United States)

    Animalu, A. O. E.; Heine, V.; Vasvari, B.

    1967-01-01

    Electronic band structure calculations phase of Ca, Sr and Ba over wide range of atomic volumes under pressure electronic band structure calculations for fcc phase of Ca, Sr and Ba over wide range of atomic volumes under pressure electronic band structure calculations for fcc phase of Ca, Sr and Ba over wide range of atomic volumes under pressure

  14. Light-stimulated cargo release from a core–shell structured nanocomposite for site-specific delivery

    International Nuclear Information System (INIS)

    Cai, Yun; Ling, Li; Li, Xiaofang; Chen, Meng; Su, Likai

    2015-01-01

    This paper reported a core–shell structured site-specific delivery system with a light switch triggered by low energy light (λ=510 nm). Its core was composed of supermagnetic Fe 3 O 4 nanoparticles for magnetic guiding and targeting. Its outer shell consisted of mesoporous silica molecular sieve MCM-41 which offered highly ordered hexagonal tunnels for cargo capacity. A light switch N1-(4aH-cyclopenta[1,2-b:5,4-b′]dipyridin-5(5aH)-ylidene)benzene-1, 4-diamine (CBD) was covalently grafted into these hexagonal tunnels, serving as light stimuli acceptor with loading content of 1.1 μM/g. This composite was fully characterized and confirmed by SEM, TEM, XRD patterns, N 2 adsorption/desorption, thermogravimetric analysis, IR, UV–vis absorption and emission spectra. Experimental data suggested that this composite had a core as wide as 150 nm and could be magnetically guided to specific sites. Its hexagonal tunnels were as long as 180 nm. Upon light stimuli of “on” and “off” states, controllable release was observed with short release time of ~900 s (90% capacity). - Graphical abstract: A core–shell structured site-specific delivery system with a light switch triggered by yellow light was constructed. Controllable release was observed with short release time of ~900 s (90% capacity). - Highlights: • A core–shell structured site-specific delivery system was constructed. • It consisted of Fe 3 O 4 core and MCM-41 shell grafted with light switch. • This delivery system was triggered by low energy light. • Controllable release was observed with short release time of ~900 s

  15. Light-stimulated cargo release from a core–shell structured nanocomposite for site-specific delivery

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Yun; Ling, Li; Li, Xiaofang [Department of Neurology, Affiliated Hospital of Hebei University, Baoding 071000 (China); Chen, Meng [Department of Rheumatology, Affiliated Hospital of Hebei University, Baoding 071000 (China); Su, Likai, E-mail: zhangdong19992003@163.com [Department of Neurology, Affiliated Hospital of Hebei University, Baoding 071000 (China)

    2015-03-15

    This paper reported a core–shell structured site-specific delivery system with a light switch triggered by low energy light (λ=510 nm). Its core was composed of supermagnetic Fe{sub 3}O{sub 4} nanoparticles for magnetic guiding and targeting. Its outer shell consisted of mesoporous silica molecular sieve MCM-41 which offered highly ordered hexagonal tunnels for cargo capacity. A light switch N1-(4aH-cyclopenta[1,2-b:5,4-b′]dipyridin-5(5aH)-ylidene)benzene-1, 4-diamine (CBD) was covalently grafted into these hexagonal tunnels, serving as light stimuli acceptor with loading content of 1.1 μM/g. This composite was fully characterized and confirmed by SEM, TEM, XRD patterns, N{sub 2} adsorption/desorption, thermogravimetric analysis, IR, UV–vis absorption and emission spectra. Experimental data suggested that this composite had a core as wide as 150 nm and could be magnetically guided to specific sites. Its hexagonal tunnels were as long as 180 nm. Upon light stimuli of “on” and “off” states, controllable release was observed with short release time of ~900 s (90% capacity). - Graphical abstract: A core–shell structured site-specific delivery system with a light switch triggered by yellow light was constructed. Controllable release was observed with short release time of ~900 s (90% capacity). - Highlights: • A core–shell structured site-specific delivery system was constructed. • It consisted of Fe{sub 3}O{sub 4} core and MCM-41 shell grafted with light switch. • This delivery system was triggered by low energy light. • Controllable release was observed with short release time of ~900 s.

  16. Controlled synthesis of multi-shelled transition metal oxide hollow structures through one-pot solution route

    Institute of Scientific and Technical Information of China (English)

    Xi Wang; Yi-Jun Yang; Ying Ma; Jian-Nian Yao

    2013-01-01

    As one type of promising candidates fot environmental and energy-related systems,multi-shelled transition metal oxide hollow structures (MS-TMOHSs) have drawn great scientific and technical interest in the past few years.This article highlights recent advances in one-pot solution synthesis of MS-TMOHSs.We begin it with an overview of synthetic strategies that have been exploited to achieve these peculiar structures.We then focus on one-pot solution approaches in the following four sections:i) soft templates directed growth; ii) Ostwald ripening; iii) controlled etching; and iv) gas bubble assisted growth.After giving a brief discussion on the unique properties and applications of these multi-shelled hollow structures,we conclude this review with the general challenges and the potential future directions of this exciting area of research.

  17. Sound-structure interaction analysis of an infinite-long cylindrical shell submerged in a quarter water domain and subject to a line-distributed harmonic excitation

    Science.gov (United States)

    Guo, Wenjie; Li, Tianyun; Zhu, Xiang; Miao, Yuyue

    2018-05-01

    The sound-structure coupling problem of a cylindrical shell submerged in a quarter water domain is studied. A semi-analytical method based on the double wave reflection method and the Graf's addition theorem is proposed to solve the vibration and acoustic radiation of an infinite cylindrical shell excited by an axially uniform harmonic line force, in which the acoustic boundary conditions consist of a free surface and a vertical rigid surface. The influences of the complex acoustic boundary conditions on the vibration and acoustic radiation of the cylindrical shell are discussed. It is found that the complex acoustic boundary has crucial influence on the vibration of the cylindrical shell when the cylindrical shell approaches the boundary, and the influence tends to vanish when the distances between the cylindrical shell and the boundaries exceed certain values. However, the influence of the complex acoustic boundary on the far-field sound pressure of the cylindrical shell cannot be ignored. The far-field acoustic directivity of the cylindrical shell varies with the distances between the cylindrical shell and the boundaries, besides the driving frequency. The work provides more understanding on the vibration and acoustic radiation behaviors of cylindrical shells with complex acoustic boundary conditions.

  18. Reinforcement of Natural Rubber with Core-Shell Structure Silica-Poly(Methyl Methacrylate Nanoparticles

    Directory of Open Access Journals (Sweden)

    Qinghuang Wang

    2012-01-01

    Full Text Available A highly performing natural rubber/silica (NR/SiO2 nanocomposite with a SiO2 loading of 2 wt% was prepared by combining similar dissolve mutually theory with latex compounding techniques. Before polymerization, double bonds were introduced onto the surface of the SiO2 particles with the silane-coupling agent. The core-shell structure silica-poly(methyl methacrylate, SiO2-PMMA, nanoparticles were formed by grafting polymerization of MMA on the surface of the modified SiO2 particles via in situ emulsion, and then NR/SiO2 nanocomposite was prepared by blending SiO2-PMMA and PMMA-modified NR (NR-PMMA. The Fourier transform infrared spectroscopy results show that PMMA has been successfully introduced onto the surface of SiO2, which can be well dispersed in NR matrix and present good interfacial adhesion with NR phase. Compared with those of pure NR, the thermal resistance and tensile properties of NR/SiO2 nanocomposite are significantly improved.

  19. A novel approach to the systematization of α-decaying nuclei, based on shell structures

    International Nuclear Information System (INIS)

    Yarman, Tolga; Azmi Altintas, Ali; Zaim, Nimet; Amon Susam, Lidya; Kholmetskii, Alexander; Arik, Metin; Ozaydin, Fatih

    2016-01-01

    We provide a novel systematization of α-decaying nuclei, starting with the classically adopted mechanism. The decay half-life of an α-disintegrating nucleus is framed, supposing that i) the α-particle is born inside the parent, then ii) it keeps on hitting the barrier, while it runs back and forth inside the parent, and hitting each time the barrier, and iii) it finally tunnels through the barrier. One can, knowing the decay half-life, consider the probability that the α-particle is born within the parent, before it is emitted, as a parameter. Under all circumstances, the decay appears to be governed by the shell structure of the given nucleus. Our approach well allows to incorporate (not only even-even nuclei, but) all nuclei, decaying via throwing an alpha particle. Though herein, we limit ourselves with just even-even nuclei, in the aim of comparing our results with the existing Geiger-Nuttal results. (orig.)

  20. Electronic structure of MnSi : The role of electron-electron interactions

    NARCIS (Netherlands)

    Carbone, F; Zangrando, M; Brinkman, A; Nicolaou, A; Bondino, F; Magnano, E; Nugroho, A. A.; Parmigiani, F; Jarlborg, T; van der Marel, D

    We present an experimental study of the electronic structure of MnSi. Using x-ray absorption spectroscopy (XAS), x-ray photoemission, and x-ray fluorescence, we provide experimental evidence that MnSi has a mixed valence ground state. We show that self-consistent local density approximation