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Sample records for wedge-shaped shell structure

  1. Metamaterials based on wedge-shaped electrodynamic structures

    Directory of Open Access Journals (Sweden)

    Mitrokhin Vladimir

    2017-01-01

    Full Text Available The paper studies a possibility of simulation of artificial composite media with negative values of the real part of the equivalent dielectric (magnetic permittivity, by the use of segments of hollow composite waveguides with cylindrical guided waves in evanescent mode. Reactive evanescent fields of wedge-shaped waveguide eigenmodes are formed in the evanescent region before the critical section of the waveguide which separates the quasistatic field region from the distributing field of the evanescent waveguide mode. The possibility of simulation is determined by the equivalence of dispersion equation of the eigenmode propagation constant and the dispersion equation for the electric (magnetic permittivity of plasma-like medium if cut-off frequency and electric (magnetic plasma frequency of the medium are equal.

  2. Modelling the wedge shape for the virtual wedge

    International Nuclear Information System (INIS)

    Chang Liyun; Ho Shengyow; Chen, Helen H W

    2003-01-01

    We present a method to model the virtual wedge shape in a 3D treatment planning system as a physical wedge. The virtual wedge shape was determined using the measured dose profile of the virtual wedge at a chosen reference depth. The differences between the calculated and the measured dose profiles for the virtual wedge were within 0.5% at the reference depth, and within 2.5% at other depths. This method provides a fast and accurate way to implement the virtual wedge into our planning system for any wedge angles. This method is also applicable to model the physical wedge shapes with comparable good results

  3. A Novel Continuous Extrusion Process to Fabricate Wedge-Shaped Light Guide Plates

    Directory of Open Access Journals (Sweden)

    Wen-Tse Hsiao

    2013-01-01

    Full Text Available Backlight modules are key components in thin-film transistor liquid crystal displays (TFT-LCD. Among the components of a backlight module, the light guide plate (LGP plays the most important role controlling the light projected to the eyes of users. A wedge-shaped LGP, with its asymmetrical structure, is usually fabricated by an injection proces, but the fabrication time of this process is long. This study proposes a continuous extrusion process to fabricate wedge-shaped LGPs. This continuous process has advantages for mass production. Besides a T-die and rollers, this system also has an in situ monitor of the melt-bank that forms during the extrusion process, helping control the plate thickness. Results show that the melt bank has a close relationship with the plate thickness. The temperature of the bottom heater and roller was adjusted to reduce the surface deformation of the wedge-shaped plate. This continuous extrusion system can successfully manufacture wedge-shaped LGPs for mass production.

  4. Complex Wedge-Shaped Matrices: A Generalization of Jacobi Matrices

    Czech Academy of Sciences Publication Activity Database

    Hnětynková, Iveta; Plešinger, M.

    2015-01-01

    Roč. 487, 15 December (2015), s. 203-219 ISSN 0024-3795 R&D Projects: GA ČR GA13-06684S Keywords : eigenvalues * eigenvector * wedge-shaped matrices * generalized Jacobi matrices * band (or block) Krylov subspace methods Subject RIV: BA - General Mathematics Impact factor: 0.965, year: 2015

  5. Spatial resolution of wedge shaped silicon microstrip detectors

    International Nuclear Information System (INIS)

    Anticic, T.; Barnett, B.; Blumenfeld, B.; Chien, C.Y.; Fisher, P.; Gougas, A.; Krizmanic, J.; Madansky, L.; Newman, D.; Orndorff, J.; Pevsner, A.; Spangler, J.

    1995-01-01

    Several wedge-shaped silicon microstrip detectors with pitches from 30 to 100 μm have been designed by our group and beam tested at the CERN SPS. We find the spatial resolution σ becomes larger at the rate of 0.21 μm per 1 μm increase in pitch, but the number of strips per cluster remains about the same as the pitch varies from 30 to 100 μm. (orig.)

  6. 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

  7. Diffusion induced flow on a wedge-shaped obstacle

    International Nuclear Information System (INIS)

    Zagumennyi, Ia V; Dimitrieva, N F

    2016-01-01

    In this paper the problem of evolution of diffusion induced flow on a wedge-shaped obstacle is analyzed numerically. The governing set of fundamental equations is solved using original solvers from the open source OpenFOAM package on supercomputer facilities. Due to breaking of naturally existing diffusion flux of a stratifying agent by the impermeable surface of the wedge a complex multi-level vortex system of compensatory fluid motions is formed around the obstacle. Sharp edges of the obstacle generate extended high-gradient horizontal interfaces which are clearly observed in laboratory experiments by high-resolution Schlieren visualization. Formation of an intensive pressure depression zone in front of the leading vertex of the wedge is responsible for generation of propulsive force resulting in a self-displacement of the obstacle along the neutral buoyancy horizon in a stably stratified environment. The size of the pressure deficiency area near the sharp vertex of a concave wedge is about twice that for a convex one. This demonstrates a more intensive propulsion mechanism in case of the concave wedge and, accordingly, a higher velocity of its self-movement in a continuously stratified medium. (paper)

  8. 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...

  9. Chemical risk factors responsible for the formation of wedge-shaped lesions

    Directory of Open Access Journals (Sweden)

    Perić Dejan

    2015-01-01

    Full Text Available Introduction: Non-carious tooth substances loss pose a major health problem of a modern man. The literature often collectively describes all non-carious lesions and is therefore difficult to compare results obtained by different authors. Chemical factors are one of the predisposing factors responsible for the formation of wedge-shaped erosions. Aim: Examination of chemical risk factors as one of the predisposing causes responsible for the formation of wedge-shaped lesions. Method: We examined 62 patients with wedge-shaped erosions (mean age 45.52 ± 12.03 years, 58.1% of men and 60 patients without erosions in the control group (mean age 34.40 ± 9.28 years, 60% men . The entire examination was completed by using a questionnaire at the Dental Clinic of the University of Pristina - Kosovska Mitrovica. salivary pH was measured by the pH meter. Results: The results show that the wedge-shaped lesions often occur equally in both men and women. Considerably often it might appear in older people but can also occur in teenagers. Patients with wedge-shaped erosion have increased acidity of saliva, a heightened sense of acid in the mouth and consume a lot more carbonated drinks compared to patients without erosions. Conclusion: Wedge-shaped lesions are more common in people older than 40 years. Taking into account the results obtained in this study it can be concluded that the chemical risk factors truly fall within the predisposing factors that may be responsible for the creation of wedge-shaped erosions.

  10. 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....

  11. Wedge-shaped parenchymal enhancement peripheral to the hepatic hemangioma : two-phase spiral CT findings

    International Nuclear Information System (INIS)

    Kim, Kyoung Won; Kim, Tae Kyoung; Han, Joon Koo; Kim, Ah Young; Lee, Hyun Ju; Song, Chi Sung; Choi, Byung Ihn

    2000-01-01

    To determine the incidence of hepatic hemangiomas associated with wedge-shaped parenchymal enhancements adjacent to the tumors as seen on two-phase spiral CT images obtained during the hepatic arterial phase and to characterize the two-phase spiral CT findings of those hemangiomas. One hundred and eight consecutive hepatic hemangiomas in 63 patients who underwent two-phase spiral CT scanning during an 11-month period were included in this study. Two-phase spiral CT scans were obtained during the hepatic arterial phase (30-second delay) and portal venous phase (65-second delay) after injection of 120 mL of contrast material at a rate of 3 mL/sec. We evaluated the frequency with which wedge-shaped parenchymal enhancement was adjacent to the hemangiomas during the hepatic arterial phase and divided hemangiomas into two groups according to whether or not wedge-shaped parenchymal enhancement was noted (Group A and Group B). The presence of such enhancement in hemangiomas was correlated with tumor size and the grade of intratumoral enhancement. In 24 of 108 hemangiomas, wedge-shaped parenchymal enhancement adjacent to hepatic tumors was seen on two-phase CT images obtained during the hepatic arterial phase. Mean hemangioma size was 22mm in group A and 24mm in group B. There was no statistically significant relationship between lesion size and the presence of wedge-shaped parenchymal enhancement adjacent to a hemangioma. In 91.7% and 100% of tumors in Group A, and in 9.6% and 17.8% in Group B, hemangiomas showed more than 50% intratumoral enhancement during the arterial and portal venous phase, respectively. Wedge-shaped parenchymal enhancements peripheral to hepatic hemangiomas was more frequently found in tumors showing more than 50% intratumoral enhancement during these two phases (p less than 0.01). Wedge-shaped parenchymal enhancements is not uncommonly seen adjacent to hepatic hemangiomas on two-phase spiral CT images obtained during the hepatic arterial phase. A

  12. Experimental Investigation on Cross Flow of Wedge-shaped Gap in the core of Prismatic VHTR

    International Nuclear Information System (INIS)

    Lee, Jeong Hun; Park, Goon Cherl; Cho, Hyoung Kyu; Yoon, Su Jong

    2014-01-01

    The core of the PMR type reactor consists of assemblies of hexagonal graphite blocks. The graphite blocks have lots of advantages for neutron economy and high temperature structural integrity. The height and flat-to-flat width of fuel bock are 793 mm and 360 mm, respectively. Each block has 108 coolant channels of which the diameter is 16 mm. And there are gaps between blocks not only vertically but also horizontally for reloading of the fuel elements. The vertical gap induces the bypass flow and through the horizontal gap the cross flow is formed. Since the complicated flow distribution occurs by the bypass flow and cross flow, flow characteristics in the core of the PMR reactor cannot be treated as a simple pipe flow. The fuel zone of the PMR core consists of multiple layers of fuel blocks. The shape change of the fuel blocks could be caused by the thermal expansion and fast-neutron induced shrinkage. It could make different axial shrinkage of fuel block and this leads to wedge-shaped gaps between two stacked fuel blocks. The cross flow is often considered as a leakage flow through the horizontal gap between stacked fuel blocks and it complicates the flow distribution in the reactor core by connecting the coolant channel and the bypass gap. Moreover, the cross flow could lead to uneven coolant distribution and consequently cause superheating of individual fuel element zones with increased fission product release. Since the core cross flow has a negative impact on safety and efficiency of VHTR, core cross flow phenomena have to be investigated to improve the core thermal margin of VHTR. To develop the cross flow loss coefficient model for determination of the flow distribution for PMR core analysis codes, study on cross flow for PMR200 core is essential. In particular, to predict the amount of flow through the cross flow gap, obtaining accurate flow loss coefficient is important. In this study, the full-scale cross flow experimental facility was constructed to

  13. [A Patient with a Wedge-shaped Pulmonary Lesion Associated with Streptococcus parasanguinis].

    Science.gov (United States)

    Miyamoto, Hiroya; Gomi, Harumi; Ishioka, Haruhiko; Shirokawa, Taijiro

    2016-05-01

    An 84-year-old man was admitted to our hospital with bloody sputum. He was found to have a right lower lobe wedge-shaped nodular lesion with chest X-ray and computed tomography of the chest. Ceftriaxone and minocycline were started empirically based on a working diagnosis of community-acquired pneumonia. Streptococcus parasanguinis was isolated with sputum cultures obtained on three consecutive days and was identified based on its biochemical properties. S. parasanguinis is a member of the sanguinis group of viridans Streptococci. It is known as a causative pathogen for endocarditis. There are very few reports of S. parasanguinis associated with pulmonary infections. The present report describes the association of S. parasanguinis with a wedge-shaped nodular lesion in the lungs.

  14. 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)

  15. Wedged-shaped, segmental changes in the liver caused by occlusion of a single hepatic vein

    International Nuclear Information System (INIS)

    Kanazawa, Susumu; Akaki, Shiro; Yasui, Kotaro; Tanaka, Akio; Hiraki, Yoshio

    1997-01-01

    We evaluated wedged-shaped, segmental changes in the liver caused by occlusion of a single hepatic vein in seven patients. The causes of occlusion were due to liver tumors in three patients, metastasis of the right adrenal gland in one, and postoperative changes in three. Changes included low attenuating on unenhanced CT, high attenuation on enhanced CT, low signal intensity on T1-weighted MRI, high signal intensity on T2-weighted MRI, high signal intensity on enhanced MRI, dense hepatogram and retrograde arterioportal shunt on hepatic arteriography. MRI and hepatic arteriography are more sensitive than CT in demonstration of those changes. (author)

  16. Temperature of Heating and Cooling of Massive, Thin, and Wedge-Shaped Plates from Hard-to-Machine Steels During Their Grinding

    Science.gov (United States)

    Dement‧ev, V. B.; Ivanova, T. N.; Dolginov, A. M.

    2017-01-01

    Grinding of flat parts occurs by solid abrasive particles due to the physicomechanical process of deformation and to the action of a process liquid at high temperatures in a zone small in volume and difficult for observation. The rate of heating and cooling depends on the change in the intensity of the heat flux and in the velocity and time of action of the heat source. A study has been made of the regularities of the influence of each of these parameters on the depth and character of structural transformations during the grinding of flat parts from hard-to-machine steels. A procedure to calculate temperature in grinding massive, thin, and wedge-shaped parts has been developed with account taken of the geometric and thermophysical parameters of the tool and the treated part, and also of cutting regimes. The procedure can be used as a constituent part in developing a system for automatic design of the technological process of grinding of flat surfaces. A relationship between the temperature in the grinding zone and the regimes of treatment has been established which makes it possible to control the quality of the surface layer of massive, thin, and wedge-shaped plates from hard-to-machine steels. The rational boundaries of shift of cutting regimes have been determined.

  17. Rainfall induced groundwater mound in wedge-shaped promontories: The Strack-Chernyshov model revisited

    Science.gov (United States)

    Kacimov, A. R.; Kayumov, I. R.; Al-Maktoumi, A.

    2016-11-01

    An analytical solution to the Poisson equation governing Strack's discharge potential (squared thickness of a saturated zone in an unconfined aquifer) is obtained in a wedge-shaped domain with given head boundary conditions on the wedge sides (specified water level in an open water body around a porous promontory). The discharge vector components, maximum elevation of the water table in promontory vertical cross-sections, quantity of groundwater seeping through segments of the wedge sides, the volume of fresh groundwater in the mound are found. For acute angles, the solution to the problem is non-unique and specification of the behaviour at infinity is needed. A ;basic; solution is distinguished, which minimizes the water table height above a horizontal bedrock. MODFLOW simulations are carried out in a finite triangular island and compare solutions with a constant-head, no-flow and ;basic; boundary condition on one side of the triangle. Far from the tip of an infinite-size promontory one has to be cautious with truncation of the simulated flow domains and imposing corresponding boundary conditions. For a right and obtuse wedge angles, there are no positive solutions for the case of constant accretion on the water table. In a particular case of a confined rigid wedge-shaped aquifer and incompressible fluid, from an explicit solution to the Laplace equation for the hydraulic head with arbitrary time-space varying boundary conditions along the promontory rays, essentially 2-D transient Darcian flows within the wedge are computed. They illustrate that surface water waves on the promontory boundaries can generate strong Darcian waves inside the porous wedge. Evaporation from the water table and sea-water intruded interface (rather than a horizontal bed) are straightforward generalizations for the Poissonian Strack potential.

  18. Stationary bubble formation and cavity collapse in wedge-shaped hoppers

    Science.gov (United States)

    Yagisawa, Yui; Then, Hui Zee; Okumura, Ko

    2016-01-01

    The hourglass is one of the apparatuses familiar to everyone, but reveals intriguing behaviors peculiar to granular materials, and many issues are remained to be explored. In this study, we examined the dynamics of falling sand in a special form of hourglass, i.e., a wedge-shaped hopper, when a suspended granular layer is stabilized to a certain degree. As a result, we found remarkably different dynamic regimes of bubbling and cavity. In the bubbling regime, bubbles of nearly equal size are created in the sand at a regular time interval. In the cavity regime, a cavity grows as sand beads fall before a sudden collapse of the cavity. Bubbling found here is quite visible to a level never discussed in the physics literature and the cavity regime is a novel phase, which is neither continuous, intermittent nor completely blocked phase. We elucidate the physical conditions necessary for the bubbling and cavity regimes and develop simple theories for the regimes to successfully explain the observed phenomena by considering the stability of a suspended granular layer and clogging of granular flow at the outlet of the hopper. The bubbling and cavity regimes could be useful for mixing a fluid with granular materials. PMID:27138747

  19. 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.

  20. Three-dimensional semi-analytical solution to groundwater flow in confined and unconfined wedge-shaped aquifers

    Science.gov (United States)

    Sedghi, Mohammad Mahdi; Samani, Nozar; Sleep, Brent

    2009-06-01

    The Laplace domain solutions have been obtained for three-dimensional groundwater flow to a well in confined and unconfined wedge-shaped aquifers. The solutions take into account partial penetration effects, instantaneous drainage or delayed yield, vertical anisotropy and the water table boundary condition. As a basis, the Laplace domain solutions for drawdown created by a point source in uniform, anisotropic confined and unconfined wedge-shaped aquifers are first derived. Then, by the principle of superposition the point source solutions are extended to the cases of partially and fully penetrating wells. Unlike the previous solution for the confined aquifer that contains improper integrals arising from the Hankel transform [Yeh HD, Chang YC. New analytical solutions for groundwater flow in wedge-shaped aquifers with various topographic boundary conditions. Adv Water Resour 2006;26:471-80], numerical evaluation of our solution is relatively easy using well known numerical Laplace inversion methods. The effects of wedge angle, pumping well location and observation point location on drawdown and the effects of partial penetration, screen location and delay index on the wedge boundary hydraulic gradient in unconfined aquifers have also been investigated. The results are presented in the form of dimensionless drawdown-time and boundary gradient-time type curves. The curves are useful for parameter identification, calculation of stream depletion rates and the assessment of water budgets in river basins.

  1. 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...

  2. 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

  3. Application of Green's differential equation to the analysis of ion-matrix sheaths around wedge-shaped cathodes

    International Nuclear Information System (INIS)

    Donolato, C

    2005-01-01

    A relation between the gradient of the electric field and mean curvature of equipotential surfaces (Green's differential equation) is applied to a two-dimensional free-boundary problem arising in the study of ion sheaths around wedge-shaped cathodes. With the assumption that the equipotential lines are hyperbolae, this relation leads to a nonlinear ordinary differential equation for the potential along the bisector line of the wedge. An approximate solution is found, which yields, in particular, the sheath width along this line as a function of the wedge angle. The resulting values are in good agreement with published results obtained by numerically solving Poisson's equation

  4. 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

  5. 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

  6. 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...

  7. 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)

  8. 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.

  9. 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...

  10. 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.

  11. 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

  12. 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.

  13. Wedge-shaped lesion in the liver seen on postoperative CT. Probable thromboembolic phenomenon in the portal venous system

    International Nuclear Information System (INIS)

    Yoshimitsu, K.; Charnsangavej, C.; Mi Park, J.; Ibukuro, K.

    1996-01-01

    Retrospective review of teaching files in our institution revealed 18 cases showing postoperative WSL in the liver. We also retrospectively reviewed CT images of the liver in 104 patients with a recent history of abdominopelvic surgery performed during a period of 12 months, as well as in 102 patients with no history of surgery during the same period to be used as control. Three additional patients with WSL were found in the postoperative group and none in the control group. Liver CT images from the 21 patients showing WSL, along with their clinical data and follow-up CT where available, were retrospectively analyzed. I.v. contrast-enhanced CT showed homogeneous higher attenuation of WSL than the surrounding liver in all cases; unenhanced CT showed low density in 5 patients, isodensity in 7 patients, and high density in 5 patients as compared with the surrounding liver. Density of unenhanced CT was significantly correlated with the presence or grade of fatty liver. In 5 cases CT demonstrated clots in the portal vein branch within the area of WSL and in 2 cases portal perfusion defects were observed on arterial portal CT, corresponding to the areas of WSL. Follow-up CT examinations were available on 15 patients: WSL became less prominent, or atrophic, or showed no change in 10, 2 and 3 patients respectively. Follow-up CT showed development of liver metastasis in only 3 cases. Only 2 of the 21 patients were clinically symptomatic; one had postoperative ileus and the other obstructive jaundice. Postoperative WSL may represent a thromboembolic phenomenon at the peripheral intrahepatic branch of the portal venous system during or after abdominopelvic surgery, resulting in a compensatory increase in the hepatic arterial flow that appears as wedge-shaped enhancement on CT. (orig./MG)

  14. 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.

  15. 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

  16. 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

  17. 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)

  18. 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.

  19. 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.

  20. 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)

  1. Three-level anterior cervical discectomy and fusion in elderly patients with wedge shaped tricortical autologous graft: A consecutive prospective series

    Directory of Open Access Journals (Sweden)

    Lee Suk

    2008-01-01

    Full Text Available Background: Treatment of multilevel cervical spondylotic myelopathy/radiculopathy is a matter of debate, more so in elderly patients due to compromised physiology. We evaluated the clinical and radiological results of cervical fusion, using wedge-shaped tricortical autologous iliac graft and Orion plate for three-level anterior cervical discectomy in elderly patients. Materials and Methods: Twelve elderly patients with mean age of 69.7 years (65-76 years were treated between April 2000 and March 2005, for three-level anterior cervical discectomy and fusion, using wedge-shaped tricortical autologous iliac graft and Orion plate. Outcome was recorded clinically according to Odom′s criteria and radiologically in terms of correction of lordosis angle and intervertebral disc height span at the time of bony union. The mean follow-up was 29.8 months (12-58 months. Results: All the patients had a complete recovery of clinical symptoms after surgery. Postoperative score according to Odom′s criteria was excellent in six patients and good in remaining six. Bony union was achieved in all the patients with average union time of 12 weeks (8-20 weeks. The mean of sum of three segment graft height collapse was 2.50 mm (SD = 2.47. The average angle of lordosis was corrected from 18.2° (SD = 2.59° preoperatively to 24.9° (SD = 4.54° at the final follow-up. This improvement in the radiological findings is statistically significant (P < 0.05. Conclusion: Cervical fusion with wedge-shaped tricortical autologous iliac graft and Orion plate for three-level anterior cervical discectomy is an acceptable technique in elderly patients. It gives satisfactory results in terms of clinical outcome, predictable early solid bony union, and maintenance of disc space height along with restoration of cervical lordosis.

  2. 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...

  3. Goldtraces on wedge-shaped artefacts from late neolithic of south Scandinavia analysed by proton induced x-ray emission spectroscopy

    International Nuclear Information System (INIS)

    Ahlberg, M.; Akselsson, R.; Forkman, B.; Rausing, G.

    1975-01-01

    Visible coloured traces on the surface of two selected wedge-shaped artefacts (pendants) of slate from the late Neolithic of South Scandinavia was analysed by means of proton-induced x-ray emission spectroscopy (PIXE). PIXE is shown to be a feasible tool in investigating surface layers of archeological significance. Three different gold-silver alloys was found on the two pendants. The results indicate that we shall have to reconsider the general accepted theories on the economic basis of the early Bronze Age in the area. (author)

  4. 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

  5. BOMB STABILIZING STRUCTURE

    Science.gov (United States)

    Kelley, J.L.; Runyan, C.E.

    1963-12-10

    A stabilizinig structure capable of minimizing deviations of a falling body such as a bomb from desired trajectory is described. The structure comprises a fin or shroud arrangement of double-wedge configuration, the feeding portion being of narrow wedge shape and the after portion being of a wider wedge shape. The structure provides a force component for keeping the body on essentially desired trajectory throughout its fall. (AEC)

  6. 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...

  7. 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

  8. 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

  9. 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

  10. 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

  11. 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.

  12. 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....

  13. High electron mobility through the edge states in random networks of c-axis oriented wedge-shaped GaN nanowalls grown by molecular beam epitaxy

    International Nuclear Information System (INIS)

    Bhasker, H. P.; Dhar, S.; Sain, A.; Kesaria, Manoj; Shivaprasad, S. M.

    2012-01-01

    Transport and optical properties of random networks of c-axis oriented wedge-shaped GaN nanowalls grown spontaneously on c-plane sapphire substrates through molecular beam epitaxy are investigated. Our study suggests a one dimensional confinement of carriers at the top edges of these connected nanowalls, which results in a blue shift of the band edge luminescence, a reduction of the exciton-phonon coupling, and an enhancement of the exciton binding energy. Not only that, the yellow luminescence in these samples is found to be completely suppressed even at room temperature. All these changes are highly desirable for the enhancement of the luminescence efficiency of the material. More interestingly, the electron mobility through the network is found to be significantly higher than that is typically observed for GaN epitaxial films. This dramatic improvement is attributed to the transport of electrons through the edge states formed at the top edges of the nanowalls.

  14. 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

  15. 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

  16. 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.

  17. 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....

  18. 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

  19. 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.

  20. 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)

  1. 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).

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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...

  8. Transport and optical properties of c-axis oriented wedge shaped GaN nanowall network grown by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Bhasker, H. P.; Dhar, S. [Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai, Maharashtra-400076 (India); Thakur, Varun; Kesaria, Manoj; Shivaprasad, S. M. [Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) Bangalore- 560064 (India)

    2014-02-21

    The transport and optical properties of wedge-shaped nanowall network of GaN grown spontaneously on cplane sapphire substrate by Plasma-Assisted Molecular Beam Epitaxy (PAMBE) show interesting behavior. The electron mobility at room temperature in these samples is found to be orders of magnitude higher than that of a continuous film. Our study reveals a strong correlation between the mobility and the band gap in these nanowall network samples. However, it is seen that when the thickness of the tips of the walls increases to an extent such that more than 70% of the film area is covered, it behaves close to a flat sample. In the sample with lower surface coverage (≈40% and ≈60%), it was observed that the conductivity, mobility as well as the band gap increase with the decrease in the average tip width of the walls. Photoluminescence (PL) experiments show a strong and broad band edge emission with a large (as high as ≈ 90 meV) blue shift, compared to that of a continuous film, suggesting a confinement of carriers on the top edges of the nanowalls. The PL peak width remains wide at all temperatures suggesting the existence of a high density of tail states at the band edge, which is further supported by the photoconductivity result. The high conductivity and mobility observed in these samples is believed to be due to a “dissipation less” transport of carriers, which are localized at the top edges (edge states) of the nanowalls.

  9. Technical note: A new wedge-shaped ionization chamber component module for BEAMnrc to model the integral quality monitoring system®

    Science.gov (United States)

    Oderinde, Oluwaseyi Michael; du Plessis, FCP

    2017-12-01

    The purpose of this study was to develop a new component module (CM) namely IQM to accurately model the integral quality monitoring (IQM) system® to be used in the BEAMnrc Monte Carlo (MC) code. The IQM is essentially a double wedge ionization chamber with the central electrode plate bisecting the wedge. The IQM CM allows the user to characterize the double wedge of this ionization chamber and BEAMnrc can then accurately calculate the dose in this CM including its enclosed air regions. This has been verified against measured data. The newly created CM was added into the standard BEAMnrc CMs, and it will be made available through the NRCC website. The BEAMnrc graphical user interface (GUI) and particle ray-tracing techniques were used to validate the IQM geometry. In subsequent MC simulations, the dose scored in the IQM was verified against measured data over a range of square fields ranging from 1 × 1-30 × 30 cm2. The IQM system is designed for the present day need for a device that could verify beam output in real-time during treatment. This CM is authentic, and it can serve as a basis for researchers that have an interest in real-time beam delivery checking using wedge-shaped ionization chamber based instruments like the IQM.

  10. Transport and optical properties of c-axis oriented wedge shaped GaN nanowall network grown by molecular beam epitaxy

    International Nuclear Information System (INIS)

    Bhasker, H. P.; Dhar, S.; Thakur, Varun; Kesaria, Manoj; Shivaprasad, S. M.

    2014-01-01

    The transport and optical properties of wedge-shaped nanowall network of GaN grown spontaneously on cplane sapphire substrate by Plasma-Assisted Molecular Beam Epitaxy (PAMBE) show interesting behavior. The electron mobility at room temperature in these samples is found to be orders of magnitude higher than that of a continuous film. Our study reveals a strong correlation between the mobility and the band gap in these nanowall network samples. However, it is seen that when the thickness of the tips of the walls increases to an extent such that more than 70% of the film area is covered, it behaves close to a flat sample. In the sample with lower surface coverage (≈40% and ≈60%), it was observed that the conductivity, mobility as well as the band gap increase with the decrease in the average tip width of the walls. Photoluminescence (PL) experiments show a strong and broad band edge emission with a large (as high as ≈ 90 meV) blue shift, compared to that of a continuous film, suggesting a confinement of carriers on the top edges of the nanowalls. The PL peak width remains wide at all temperatures suggesting the existence of a high density of tail states at the band edge, which is further supported by the photoconductivity result. The high conductivity and mobility observed in these samples is believed to be due to a “dissipation less” transport of carriers, which are localized at the top edges (edge states) of the nanowalls

  11. 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...

  12. 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.

  13. 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

  14. 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

  15. 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.)

  16. 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)

  17. 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.)

  18. 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....

  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. 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.

  2. 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

  3. 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.)

  4. 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

  5. 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

  6. 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)

  7. 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

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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....

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. 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)

  3. 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.

  4. 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)

  5. 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 $\\...

  6. 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.

  7. 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.

  8. 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)

  9. 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.

  10. 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

  11. 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

  12. 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

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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

  1. 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.

  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. 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...

  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. 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.

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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

  11. 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.

  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. 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.

  16. 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.

  17. 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

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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 ...

  6. 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

  7. 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

  8. 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.

  9. 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

  10. 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

  11. 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)

  12. 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

  13. 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.)

  14. 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

  15. 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.

  16. 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.

  17. 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

  18. 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

  19. 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.

  20. 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.)

  1. 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

  2. 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

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. 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...

  18. 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.)

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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

  6. 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.

  7. 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)

  8. 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.

  9. 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

  10. 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

  11. 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)

  12. 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

  13. 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....

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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)

  19. 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.

  20. 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.

  1. 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

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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

  12. 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)

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. 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

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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

  8. 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)

  9. 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.

  10. 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.

  11. 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.

  12. 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

  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. 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. 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.

  16. 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).

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.)

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.)

  18. 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.

  19. Experimental approach towards shell structure at 100Sn and 78Ni

    International Nuclear Information System (INIS)

    Grawe, H.; Gorska, M.; Fahlander, C.

    2000-07-01

    The status of experimental approach to 100 Sn and 78 Ni is reviewed. Revised single particle energies for neutrons are deduced for the N=Z=50 shell closure and evidence for low lying I π =2 + and 3 - states is presented. Moderate E2 polarisation charges of 0.1 e and 0.6 e are found to reproduce the experimental data when core excitation of 100 Sn is properly accounted for in the shell model. For the neutron rich Ni region no conclusive evidence for a N=40 subshell is found, whereas firm evidence for the persistence of the N=50 shell at 78 Ni is inferred from the existence of seniority isomers. The disappearance of this isomerism in the mid νg 9/2 shell is discussed. (orig.)

  20. Semiclassical moment of inertia shell-structure within the phase-space approach

    International Nuclear Information System (INIS)

    Gorpinchenko, D V; Magner, A G; Bartel, J; Blocki, J P

    2015-01-01

    The moment of inertia for nuclear collective rotations is derived within a semiclassical approach based on the cranking model and the Strutinsky shell-correction method by using the non-perturbative periodic-orbit theory in the phase-space variables. This moment of inertia for adiabatic (statistical-equilibrium) rotations can be approximated by the generalized rigid-body moment of inertia accounting for the shell corrections of the particle density. A semiclassical phase-space trace formula allows us to express the shell components of the moment of inertia quite accurately in terms of the free-energy shell corrections for integrable and partially chaotic Fermi systems, which is in good agreement with the corresponding quantum calculations. (paper)

  1. On the structural behavior of ship's shell structures due to impact loading

    Directory of Open Access Journals (Sweden)

    Hyung Kyun Lim

    2018-01-01

    Full Text Available When collision accident between ships or between ship and offshore platform occurs, a common phenomenon that occurs in structures is the plastic deformation accompanied by a large strain such as fracture. In this study, for the rational design against accidental limit state, the plastic material constants of steel plate which is heated by line heating and steel plate formed by cold bending procedure have been defined through the numerical simulation for the high speed tension test. The usefulness of the material constants included in Cowper–Symonds model and Johnson–Cook model and the assumption that strain rate can be neglected when strain rate is less than the intermediate speed are verified through free drop test as well as comparing with numerical results in several references. This paper ends with describing the future study.

  2. Nuclear structure of the N = Z odd - odd nuclei around N=28 closed shell interpreted with IBFFM

    International Nuclear Information System (INIS)

    Dragulescu, E.; Serbanut, G. C.; Serbanut, I.

    2001-01-01

    In the very recent years the knowledge of the level structure at lower and higher energies in the fpg shell N=Z nuclei has renewed a growing interest due to major improvements in the theoretical techniques. Going away from closed shell, the shell model calculations rapidly exhaust computer capabilities and we must resort to the model observed on collective phenomena. The fpg odd-odd N = Z nuclei close to the doubly magic 56 Ni nucleus are good candidates to investigate the competition between collective and single-particle excitations. Here part of the results obtained from an exhaustive systematic study of the self conjugate doubly-odd nuclei with A > 62: 62 Ga and 66 As nuclei using the interacting - boson - fermion - fermion - model (IBFFM) is presented. The odd-odd nuclei are described in the framework of the IBFFM by coupling valence shell proton and neutron quasiparticles to even-even core described in the interacting - boson model. In the first step of the calculations the core parameters for 60 Zn and 64 Ge cores were fitted to the energies of their excited states. In the second step of calculations, we have adjusted the IBFM proton Hamiltonian to the low - lying levels of 63 Ga and 67 As nuclei and IBFM neutron Hamiltonian of low - lying levels of 61 Zn and 65 Ge nuclei involved in the cases of the structure of odd-odd 62 Ga and 66 As nuclei. We have finally calculated the level spectra and electromagnetic properties of above mentioned nuclei. The IBFFM positive - parity energy spectra are compared with experimental ones. The calculations show a reasonable agreement with experimental data and existing shell - model calculations. (authors)

  3. Shell colour, temperature, (micro)habitat structure and predator pressure affect the behaviour of Cepaea nemoralis

    Science.gov (United States)

    Rosin, Zuzanna M.; Kwieciński, Zbigniew; Lesicki, Andrzej; Skórka, Piotr; Kobak, Jarosław; Szymańska, Anna; Osiejuk, Tomasz S.; Kałuski, Tomasz; Jaskulska, Monika; Tryjanowski, Piotr

    2018-06-01

    Although shell colour polymorphism of the land snail Cepaea nemoralis is a well-known phenomenon, proximate and ultimate factors driving its evolution remain uncertain. Polymorphic species show variation in behavioural responses to selective forces. Therefore, we estimated effects of various environmental factors (temperature, humidity, food availability, (micro)habitat structure and predatory pressure) on behavioural response (frequency of locomotion, climbing and hiding) of C. nemoralis morphs, in experimental and natural conditions. In the experimental part of study, the frequency of locomotion was negatively affected by temperature and the presence of food and positively influenced by the presence of light. Morphs significantly differed in behavioural responses to environmental variability. Pink mid-banded and yellow five-banded morphs climbed less often and hide in shelter more often than yellow and pink unbanded individuals when temperature was low and food was absent. Snails fed most often at moderate temperature compared to low and high temperatures. Field investigations partially confirmed differences among morphs in frequency of climbing, but not in terms of probability of hiding in sheltered sites. In natural colonies, temperature and (micro)habitat structure significantly affected frequency of climbing as well as hiding in shelter. Snails more often hid in sheltered sites where thrushes preyed on Cepaea. Tendency of unbanded morphs to climb trees may have evolved under avian predatory pressure as thrushes forage on a ground. Tendency of banded morphs to hide in sheltered sites may reflect prey preferences for cryptic background. The results implicate that differential behaviour of C. nemoralis morphs compensate for their morphological and physiological limitations of adaptation to habitat.

  4. Constructing Repairable Meta-Structures of Ultra-Broad-Band Electromagnetic Absorption from Three-Dimensional Printed Patterned Shells.

    Science.gov (United States)

    Song, Wei-Li; Zhou, Zhili; Wang, Li-Chen; Cheng, Xiao-Dong; Chen, Mingji; He, Rujie; Chen, Haosen; Yang, Yazheng; Fang, Daining

    2017-12-13

    Ultra-broad-band electromagnetic absorption materials and structures are increasingly attractive for their critical role in competing with the advanced broad-band electromagnetic detection systems. Mechanically soft and weak wax-based materials composites are known to be insufficient to serve in practical electromagnetic absorption applications. To break through such barriers, here we developed an innovative strategy to enable the wax-based composites to be robust and repairable meta-structures by employing a three-dimensional (3D) printed polymeric patterned shell. Because of the integrated merits from both the dielectric loss wax-based composites and mechanically robust 3D printed shells, the as-fabricated meta-structures enable bear mechanical collision and compression, coupled with ultra-broad-band absorption (7-40 and 75-110 GHz, reflection loss  smaller than -10 dB) approaching state-of-the-art electromagnetic absorption materials. With the assistance of experiment and simulation methods, the design advantages and mechanism of employing such 3D printed shells for substantially promoting the electromagnetic absorption performance have been demonstrated. Therefore, such universal strategy that could be widely extended to other categories of wax-based composites highlights a smart stage on which high-performance practical multifunction meta-structures with ultra-broad-band electromagnetic absorption could be envisaged.

  5. A Study on the Plasmonic Properties of Silver Core Gold Shell Nanoparticles: Optical Assessment of the Particle Structure

    Science.gov (United States)

    Mott, Derrick; Lee, JaeDong; Thi Bich Thuy, Nguyen; Aoki, Yoshiya; Singh, Prerna; Maenosono, Shinya

    2011-06-01

    This paper reports a qualitative comparison between the optical properties of a set of silver core, gold shell nanoparticles with varying composition and structure to those calculated using the Mie solution. To achieve this, silver nanoparticles were synthesized in aqueous phase from a silver hydroxide precursor with sodium acrylate as dual reducing-capping agent. The particles were then coated with a layer of gold with controllable thickness through a reduction-deposition process. The resulting nanoparticles reveal well defined optical properties that make them suitable for comparison to ideal calculated results using the Mie solution. The discussion focuses on the correlation between the synthesized core shell nanoparticles with varying Au shell thickness and the Mie solution results in terms of the optical properties. The results give insight in how to design and synthesize silver core, gold shell nanoparticles with controllable optical properties (e.g., SPR band in terms of intensity and position), and has implications in creating nanoparticle materials to be used as biological probes and sensing elements.

  6. HANFORD DOUBLE-SHELL TANK THERMAL and SEISMIC PROJECT. DYTRAN ANALYSIS OF SEISMICALLY INDUCED FLUID-STRUCTURE INTERACTION IN A HANFORD DOUBLE-SHELL PRIMARY TANK

    International Nuclear Information System (INIS)

    MACKEY, T.C.

    2006-01-01

    M and D Professional Services, Inc. (M and D) is under subcontract to Pacific Northwest National Laboratories (PNNL) to perform seismic analysis of the Hanford Site Double-Shell Tanks (DSTs) in support of a project entitled ''Double-Shell Tank (DSV Integrity Project-DST Thermal and Seismic Analyses)''. The overall scope of the project is to complete an up-to-date comprehensive analysis of record of the DST System at Hanford in support of Tri-Party Agreement Milestone M-48-14. The work described herein was performed in support of the seismic analysis of the DSTs. The thermal and operating loads analysis of the DSTs is documented in Rinker et al. (2004). The overall seismic analysis of the DSTs is being performed with the general-purpose finite element code ANSYS'. The global model used for the seismic analysis of the DSTs includes the DST structure, the contained waste, and the surrounding soil. The seismic analysis of the DSTs must address the fluid-structure interaction behavior and sloshing response of the primary tank and contained liquid. ANSYS has demonstrated capabilities for structural analysis, but has more limited capabilities for fluid-structure interaction analysis. The purpose of this study is to demonstrate the capabilities and investigate the limitations of the finite element code MSC.Dytranz for performing a dynamic fluid-structure interaction analysis of the primary tank and contained waste. To this end, the Dytran solutions are benchmarked against theoretical solutions appearing in BNL 1995, when such theoretical solutions exist. When theoretical solutions were not available, comparisons were made to theoretical solutions to similar problems, and to the results from ANSYS simulations. Both rigid tank and flexible tank configurations were analyzed with Dytran. The response parameters of interest that are evaluated in this study are the total hydrodynamic reaction forces, the impulsive and convective mode frequencies, the waste pressures, and slosh

  7. Assembly of core–shell structured porous carbon–graphene composites as anode materials for lithium-ion batteries

    International Nuclear Information System (INIS)

    Guo, Rong; Zhao, Li; Yue, Wenbo

    2015-01-01

    As potential anode materials for lithium-ion batteries, mesoporous carbons such as CMK-3 and CMK-8 usually show stable cycling performances but only slightly higher reversible capacities than commercial graphite. Graphene has much higher theoretical capacity than that of graphite in theory. However, its electrochemical behavior is not as good as expected due to the aggregation of graphene nanosheets. Herein we describe a novel strategy for the preparation of core–shell structured porous carbon–graphene composites. Compared to pure porous carbons or pure graphene nanosheets, these novel composites exhibit superior electrochemical performances including higher reversible capacities and better cycle/rate performances. This core–shell structure can avoid the aggregation of graphene nanosheets as well as may stabilize the mesostructure of porous carbon, which is beneficial to improving the electrochemical performances of the composites

  8. 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.

  9. 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.

  10. Structural Control of InP/ZnS Core/Shell Quantum Dots Enables High-quality White LEDs.

    Science.gov (United States)

    Ganesh Kumar, Baskaran; Sadeghi, Sadra; Melikov, Rustamzhon; Mohammadi Aria, Mohammed; Bahmani Jalali, Houman; Ow-Yang, Cleva; Nizamoglu, Sedat

    2018-05-30

    Herein, we demonstrate that the structural and optical control of InP-based quantum dots can lead to high-performance LEDs. Zinc sulphide (ZnS) shells passivate the InP quantum dot core and increase the quantum yield in green-emitting quantum dots by 13-fold and red-emitting quantum dots by 8-fold. The optimised quantum dots are integrated in the liquid-state to eliminate aggregation induced emission quenching and we fabricated white LEDs with warm, neutral, and cool white appearance by the down-conversion mechanism. The quantum dot-functionalized white LEDs achieve luminous efficiency up to 14.7 lm/W and colour-rendering index up to 80. The structural and optical control of InP/ZnS core/shell quantum dots enable 23-fold enhancement in luminous efficiency of white LEDs compared to ones containing only QDs of InP core. © 2018 IOP Publishing Ltd.

  11. 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.

  12. Statistical analysis on hollow and core-shell structured vanadium oxide microspheres as cathode materials for Lithium ion batteries

    Directory of Open Access Journals (Sweden)

    Xing Liang

    2018-06-01

    Full Text Available In this data, the statistical analyses of vanadium oxide microspheres cathode materials are presented for the research article entitled “Statistical analyses on hollow and core-shell structured vanadium oxides microspheres as cathode materials for Lithium ion batteries” (Liang et al., 2017 [1]. This article shows the statistical analyses on N2 adsorption-desorption isotherm and morphology vanadium oxide microspheres as cathode materials for LIBs. Keywords: Adsorption-desorption isotherm, Pore size distribution, SEM images, TEM images

  13. 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.

  14. Preparation of core-shell structured CaCO3 microspheres as rapid and recyclable adsorbent for anionic dyes

    Science.gov (United States)

    Zhao, Mengen; Chen, Zhenhua; Lv, Xinyan; Zhou, Kang; Zhang, Jie; Tian, Xiaohan; Ren, Xiuli; Mei, Xifan

    2017-09-01

    Core-shell structured CaCO3 microspheres (MSs) were prepared by a facile, one-pot method at room temperature. The adsorbent dosage and adsorption time of the obtained CaCO3 MSs were investigated. The results suggest that these CaCO3 MSs can rapidly and efficiently remove 99-100% of anionic dyes within the first 2 min. The obtained CaCO3 MSs have a high Brunauer-Emmett-Teller surface area (211.77 m2 g-1). In addition, the maximum adsorption capacity of the obtained CaCO3 MSs towards Congo red was 99.6 mg g-1. We also found that the core-shell structured CaCO3 MSs have a high recycling capability for removing dyes from water. Our results demonstrate that the prepared core-shell structured CaCO3 MSs can be used as an ideal, rapid, efficient and recyclable adsorbent to remove dyes from aqueous solution.

  15. 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

  16. PARCS - A pre-stressed and reinforced concrete shell element for analysis of containment structures

    International Nuclear Information System (INIS)

    Buragohain, D.N.; Mukherjee, A.

    1993-01-01

    Containment structures are designed as pressure vessels against a huge internal pressure build up in the event of a postulated LOCA. In such situations the containment structures experience predominantly in-plane stress in tension. Therefore, pre-stressed concrete has been very frequently used for the construction of containment. For larger plants a dual containment with a pre-stressed concrete inner containment and a reinforced concrete outer containment has been adopted. These structures are required to perform within very stringent safety requirements under extremely severe loading. Naturally, their design has attracted a lot of investigators and a huge volume of literature has been published in previous SMiRT conferences. However, it seems that the structural modeling of the containment has not developed accordingly. It is a common practice to consider the concrete section only in the model and the effects of pre-stress and reinforcements are usually neglected. This is due to the difficulty in including these effects without generating an unduly large model. To include these effects using the existing software, the concrete can be modeled with 3D elements. The reinforcements can be included in the model as bar or cable elements. However, that would require a nodal line along every reinforcement. Therefore, this method would generate a huge model unmanageable even with modern computing facilities. Alternatively, the reinforcements can be assumed to be smeared uniformly within the structure and an average property can be included. This model is acceptable when the reinforcements are very closely spaced. However, for sparsely spaced reinforcements it would result in loss of accuracy, especially in important areas like the vicinity of large openings. In this paper a shell element for the analysis of pre-stressed and reinforced concrete structures has been proposed which alleviates this difficulty. This element can accommodate the reinforcing bars or cables anywhere

  17. (3He,α) reaction mechanism at high energy and neutron inner shell structure

    International Nuclear Information System (INIS)

    Wiele, J. van de.

    1980-01-01

    The ( 3 He,α) reaction on 12 C, 16 O, 28 Si, 58 Ni, 90 Zr, 118 Sn, 124 Sn and 208 Pb targets has been studied at Esub( 3 He) = 217 MeV (or 205 MeV) in order to investigate the reaction mechanism at high energy and large momentum transfer. The reaction yields large cross sections at very forward angles and strongly enhances the largest orbital momentum transfer. The angular distribution shapes are well reproduced in the frame-work of the Z-R- D.W.B.A. analysis if we use a unique empirical α-potential: Vsub(α)(Esub(α)) = Vsub( 3 He)(3/4 Esub(α)) + Vsub(n)(1/4 Esub(α)). The excitation energy spectra have been measured up to 100 MeV in the residual light and medium nuclei and up to about 16 MeV in heavy nuclei. In addition to the well-known low-lying levels, peaks or broad structures are observed for each nucleus at higher excitation energies. They are attributed to pick up from inner shells: 1s( 11 C and 15 O), 1p( 27 Si), 1d5/2 + 1p( 57 Ni), 1f7/2( 89 Zr) 1g9/2 117 Sn, 123 Sn and 1h11/2( 207 Pb). Selectivity and localization of direct and indirect pick up ( 3 He,α) reactions were studied. Finite range calculations show that this reaction is not very sensitive to the details of the range from function but only to D 0 coefficient and range R. A microscopic α-nucleus optical potential calculated with n-n dependent and independent density forces is able to reproduce both elastic scattering and pick up reaction angular distributions [fr

  18. Nuclear structure in the vicinity of shell closures far from stability

    International Nuclear Information System (INIS)

    Grawe, H.; Gorska, M.; Doering, J.

    2000-09-01

    The status of experimental approach to 100 Sn and 78 Ni is reviewed. Revised single particle energies for neutrons are deduced for the N=Z=50 shell closure and evidence for low lying I π =2 + and 3 - states is presented. Moderate E2 polarization charges of 0.1 e and 0.6 e are found to reproduce the experimental data when core excitation of 100 Sn is properly accounted for in the shell model. For the neutron rich Ni region no conclusive evidence for an N=40 subshell is found, whereas firm evidence for the persistence of the N=50 shell at 78 Ni is inferred from the existence of seniority isomers. The disappearance of this isomerism in the mid νg 9/2 shell is discussed. The spectroscopy of 216 Th disproves the existence of a Z=92 shell gap as predicted by some recent mean field calculations. Inversion of the πh 9/2 and f 7/2 orbitals at Z=90 is ascribed to the coupling of the f 7/2 (and i 13/2 ) protons to the low-lying 3 - state (ℎω 3 =1.69 MeV). (orig.)

  19. Au@Pd core-shell nanobricks with concave structures and their catalysis of ethanol oxidation.

    Science.gov (United States)

    Wang, Wenjin; Zhang, Jie; Yang, Shengchun; Ding, Bingjun; Song, Xiaoping

    2013-10-01

    Au@Pd core-shell nanobricks (CNBs) with concave surfaces and Pd shells with a thickness of approximately 5 nm were synthesized by co-reduction of HAuCl4 and H2 PdCl4 in the presence of Au seeds and Ag ions. These as-synthesized concave CNBs exhibit significantly enhanced catalytic activity for the electrooxidation of ethanol in alkaline media compared to the commercially-used Pd black. The improved performance of the Au@Pd CNBs can be attributed to the exposed stepped surfaces, high-index facets, and the synergistic effects of the core and shell metals. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Large-scale micromagnetic simulation of Nd-Fe-B sintered magnets with Dy-rich shell structures

    Directory of Open Access Journals (Sweden)

    T. Oikawa

    2016-05-01

    Full Text Available Large-scale micromagnetic simulations have been performed using the energy minimization method on a model with structural features similar to those of Dy grain boundary diffusion (GBD-processed sintered magnets. Coercivity increases as a linear function of the anisotropy field of the Dy-rich shell, which is independent of Dy composition in the core as long as the shell thickness is greater than about 15 nm. This result shows that the Dy contained in the initial sintered magnets prior to the GBD process is not essential for enhancing coercivity. Magnetization reversal patterns indicate that coercivity is strongly influenced by domain wall pinning at the grain boundary. This observation is found to be consistent with the one-dimensional pinning theory.

  1. Laser spectroscopy of cadmium isotopes: probing the nuclear structure between the neutron 50 and 82 shell closures

    CERN Multimedia

    Blaum, K; Stroke, H H; Krieger, A R

    We propose to study the isotopic chain of cadmium with high-resolution laser spectroscopy for the first time. Our goal is to determine nuclear spins, moments and root-mean-square charge radii of ground and isomeric states between the neutron 50 and 82 shell closures, contributing decisively to a better understanding of the nuclear structure in the vicinity of the doubly-magic $^{100}$Sn and $^{132}$Sn. On the neutron-rich side this is expected to shed light on a shell-quenching hypothesis and consequently on the duration of the r-process along the waiting-point nuclei below $^{130}$Cd. On the neutron-deficient side it may elucidate the role of the cadmium isotopes in the rp-process for rapidly accreting neutron stars.

  2. Facile synthesis of core-shell Cu2O@ ZnO structure with enhanced photocatalytic H2 production

    Science.gov (United States)

    Zhang, Yong-Hui; Jiu, Bei-Bei; Gong, Fei-Long; Lu, Kuan; Jiang, Nan; Zhang, Hao-Li; Chen, Jun-Li

    2018-05-01

    Core-shell Cu2O@ZnO composites were synthesized successfully based on a one-pot hydrothermal method in the presence of dioctyl sulfosuccinate sodium salt (AOT) surfactant. The Cu2O can be converted to rough core-shell Cu2O@ZnO structure by adjusting the amount of zinc powder added. The as-synthesized Cu2O@ZnO composites exhibited excellent photocatalytic activity and the amount of H2 generated using these composites was 4.5-fold more than that produced with Cu2O cubes. A possible photocatalytic mechanism for the Cu2O@ZnO composites with enhanced photocatalytic activity could be the separation by ZnO of the effective charge carriers.

  3. PREFACE: 11th International Spring Seminar on Nuclear Physics: Shell Model and Nuclear Structure - achievements of the past two decades

    Science.gov (United States)

    2015-02-01

    The 11th International Seminar on Nuclear Physics was held in Ischia from May 12 to May 16, 2014. This Seminar was dedicated to Aldo Covello, who has been the promoter of this series of meetings, which started in Sorrento in 1986 and continued with meetings held every two or three years in the Naples area. Aldo's idea was to offer to a group of researchers, actively working in selected fields of Nuclear Physics, the opportunity to confront their points of view in a lively and informal way. The choice for the period of the year, Spring, as well as the sites chosen reflected this intent. The first meeting was of a purely theoretical nature, but it was immediately clear that the scope of these conferences needed to be enlarged calling into play the experimental community. Then, starting from the second meeting, all the following ones have been characterized by fruitful discussion between theoretical and experimental researchers on current achievements and future developments of nuclear structure. This may be read, in fact, as one of the motivating factors for Aldo's election as Fellow of the American Physical Society in 2008 "... for his outstanding contributions to the international nuclear physics community by providing, for over two decades, a venue for theorists and experimentalists to share their latest ideas." The present meeting, organized by Aldo's former students and with the benefit of his suggestions, has maintained this tradition. The title "Shell model and nuclear structure: achievements of the past two decades" recalls that of the 2nd International Spring Seminar "Shell Model and Nuclear Structure: where do we stand?". The main aim of this 11th Seminar was, in fact, to discuss the changes of the past two decades on our view of nuclei in terms of shell structure as well as the perspectives of the shell model, which has been one of the key points in Aldo's research. This point is well accounted by the Opening Speech of Igal Talmi, one of the fathers of the

  4. Studies on II-VI and III-V semiconductor nanostructures. Introduction of the core/shell/shell structure and development of CdSe nanocrystals in an automatized procedure; Untersuchungen an II-VI und III-V Halbleiternanostrukturen. Einfuehrung der Core/shell/shell-Struktur und Darstellung von CdSe-Nanokristallen in einem automatisierten Verfahren

    Energy Technology Data Exchange (ETDEWEB)

    Mekis, I.

    2005-11-15

    The work in this dissertation is focused on the development and characterization of fluorescent II-VI and III-V-Nanomaterials. Highly luminescent and photostable Nanocrystals with narrow size distributions were prepared. It was shown that nearly monodisperse CdSe-Nanocrystals could be prepared from Cd(Ac){sub 2} and TOPSe in a mixture of TOPO/TOP/HDA/TDPA. Nearly monodisperse CdSe/CdS-Core/shell-Nanocrystals have been prepared in a one-pot-synthesis by injection of H{sub 2}S-Gas into a freshly prepared crude solution of CdSe. The passivation of the CdSe-core with an inorganic shell of CdS resulted in the drastic improvement of the photoluminescence-efficiency of the colloidal solution. Reproducible room-temperature quantum yields reached up to a value of 85%. Photostability investigations have proved the enhanced stability of CdSe/CdS-Nanocrystals compared to CdSe-Nanocrystals under illumination with UV-Light. A novel type of luminescent semiconductor nanocrystal structure has been developed, consisting of a CdSe core and two anorganic shells. Highly fluorescent and nearly monodisperse CdSe/CdS/ZnS- and CdSe/ZnSe/ZnS-Core/shell/shell-nanocrystals have been prepared via organometallic- and acetate-precursors. The Core/she ll/shell particles reached reproducible room-temperature quantum yields up to 85%. Photostability investigations among CdSe-core, CdSe/CdS-Core/shell- and CdSe/CdS/ZnS- Core/shell/-shell-nanocrystals under illumination with UV-light have proved the highest photostability of the Core/shell/shell-particles. The photostabilities of CdSe/ZnSe/ZnS-and CdSe/ZnS-nanocrystals were compared under illumination with intense laser-beam in air. Another part of this work focused on the development of an automated synthesis procedure of CdSe-nanocrystals by constructing and implementing a flow-reactor system. The size and structure of prepared nanocrystals depended considerably on the Cd:Se-precursorratio and the flow-rate. The preparation of CdSe using Cd(Ac)2

  5. Palm-Kernel Shell Concrete For Structural Use – A Preliminary ...

    African Journals Online (AJOL)

    The paper reports on the results of an investigation into the physical and strength characteristics of concrete (norminal mixes), which contains crushed palm-kernel shell as fine aggregates instead of normal river sand. 66 No beams of 100mm x 100mm x 500mm sizes and 396 No 100mm cubes as well were tested with ...

  6. Structural and magnetic properties of CoO-Pt core-shell nanoparticles

    Czech Academy of Sciences Publication Activity Database

    Zeleňáková, A.; Zeleňák, V.; Michalik, Štefan; Kováč, J.; Meisel, M. W.

    2014-01-01

    Roč. 89, č. 10 (2014), "104417-1"-"104417-10" ISSN 1098-0121 Institutional support: RVO:68378271 Keywords : CoO-Pt core shell nanoparticles * superparamagnetism * superspin glass state * x-ray diffraction * x-ray absorption spectroscopy Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 3.736, year: 2014

  7. Bird's nest-like nanographene shell encapsulated Si nanoparticles - Their structural and Li anode properties

    Science.gov (United States)

    Li, Beibei; Jiang, Yizhe; Jiang, Fan; Cao, Daxian; Wang, Hongkang; Niu, Chunming

    2017-02-01

    Bird's nest-like nanographene shell (NGS) encapsulated Si@SiO2 nanoparticles have been prepared by a simple chemical vapor deposition (CVD) method. The shell is comprised of a conformed coating with 4-10 layers of the nanographene, and nanographene spikes with the same thickness grown on the coating surface. The high crystallinity of the shell is demonstrated by XRD, HRTEM and Raman characterization. After SiO2 has been removed, distinctive void space is created between Si core and nested NGS. Statistical estimation from TEM images of 50 Si@void@NGS particles shows that the volume of void space is about 2.82 times of that of Si nanoparticle, sufficient to accommodate volume change from Si to Li15Si4. Evaluation of Si@void@NGS for Li ion anode reveals a specific capacity of 2634 mAh g-1 at a current density of 0.2 A g-1, and an excellent rate and cycling performance. The capacity decreases by 5.2%-2497 mAh g-1 after cycling at current densities of 0.5, 1, 2, 5 10, 20 A g-1. The excellent performance can be attributed to high conductivity and high stability of the shell, which remains intact after repeated cycling.

  8. Local functional derivative of the total energy and the shell structure in atoms and molecules

    NARCIS (Netherlands)

    Pino, R.; Markvoort, Albert. J.; Santen, van R.A.; Hilbers, P.A.J.

    2003-01-01

    The full and local Thomas–Fermi–Dirac energy functional derivatives are evaluated at Hartree–Fock densities for several atoms and molecules. These functions are interpreted as local chemical potentials and related mainly to kinetic energy functional derivatives. They are able to reveal the shell

  9. Solution strategies for linear and nonlinear instability phenomena for arbitrarily thin shell structures

    International Nuclear Information System (INIS)

    Eckstein, U.; Harte, R.; Kraetzig, W.B.; Wittek, U.

    1983-01-01

    In order to describe nonlinear response and instability behaviour the paper starts with the total potential energy considering the basic kinematic equations of a consistent nonlinear shell theory for large displacements and moderate rotations. The material behaviour is assumed to be hyperelastic and isotropic. The incrementation and discretization of the total potential energy leads to the tangent stiffness relation, which is the central equation of computational algorithms based on combined incremental and iterative techniques. Here a symmetrized form of the RIKS/WEMPNER-algorithm for positive and negative load incrementation represents the basis of the nonlinear solution technique. To detect secondary equilibrium branches at points of neutral equilibrium within nonlinear primary paths a quadratic eigenvalue-problem has to be solved. In order to follow those complicated nonlinear response phenomena the RIKS/WEMPNER incrementation/iteration process is combined with a simultaneous solution of the linearized quadratic eigenvalue-problem. Additionally the essentials of a recently derived family of arbitrarily curved shell elements for linear (LACS) and geometrically nonlinear (NACS) shell problems are presented. The main advantage of these elements is the exact description of all geometric properties as well as the energy-equivalent representation of the applied loads in combination with an efficient algorithm to form the stiffness submatrices. Especially the NACS-elements are designed to improve the accuracy of the solution in the deep postbuckling range including moderate rotations. The derived finite elements and solution strategies are applied to a certain number of typical shell problems to prove the precision of the shell elements and to demonstrate the possibilities of tracing linear and nonlinear bifurcation problems as well as snap-through phenomena with and without secondary bifurcation branches. (orig.)

  10. 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.

  11. Thermal and magnetic properties of ternary mixed Ising nanoparticles with core–shell structure: Effective-field theory approach

    International Nuclear Information System (INIS)

    Kantar, Ersin; Keskin, Mustafa

    2014-01-01

    We propose a ternary Ising spins (1/2, 1, 3/2) model to investigate the thermal and magnetic properties of magnetic nanoparticles with core–shell structure within the framework of the effective-field theory with correlations. The center site of the core is occupied by σ=±1/2 spin, while those surrounding the center site are occupied by S=±1, 0 spins and the shell sites are occupied by m=±1/2,±3/2 spins. Thermal behaviors of the core and shell magnetizations, susceptibilities and internal energies as well as total magnetization are examined. In order to confirm the stability of the solutions we also investigate the free energy of the system. According to the values of Hamiltonian parameters, the system undergoes first- and second-order phase transitions. Phase diagrams are calculated and discussed in detail. We find that the system exhibits a tricritical point, reentrant and five different type (Q, P, R, S and W) of compensation behaviors that strongly depend on interaction parameters. The results are in good agreement with some experimental and theoretical results. - Highlights: • Thermal and magnetic properties of ternary Ising nanoparticles are studied. • Phase diagrams within the EFT with correlations are calculated and discussed. • The effects of the exchange interactions and crystal field have been studied. • Reentrant phenomena and compensation behaviors have been found

  12. Thermal and magnetic properties of ternary mixed Ising nanoparticles with core–shell structure: Effective-field theory approach

    Energy Technology Data Exchange (ETDEWEB)

    Kantar, Ersin [Department of Physics, Erciyes University, 38039 Kayseri (Turkey); Institute of Science, Erciyes University, 38039 Kayseri (Turkey); Keskin, Mustafa, E-mail: keskin@erciyes.edu.tr [Department of Physics, Erciyes University, 38039 Kayseri (Turkey)

    2014-01-15

    We propose a ternary Ising spins (1/2, 1, 3/2) model to investigate the thermal and magnetic properties of magnetic nanoparticles with core–shell structure within the framework of the effective-field theory with correlations. The center site of the core is occupied by σ=±1/2 spin, while those surrounding the center site are occupied by S=±1, 0 spins and the shell sites are occupied by m=±1/2,±3/2 spins. Thermal behaviors of the core and shell magnetizations, susceptibilities and internal energies as well as total magnetization are examined. In order to confirm the stability of the solutions we also investigate the free energy of the system. According to the values of Hamiltonian parameters, the system undergoes first- and second-order phase transitions. Phase diagrams are calculated and discussed in detail. We find that the system exhibits a tricritical point, reentrant and five different type (Q, P, R, S and W) of compensation behaviors that strongly depend on interaction parameters. The results are in good agreement with some experimental and theoretical results. - Highlights: • Thermal and magnetic properties of ternary Ising nanoparticles are studied. • Phase diagrams within the EFT with correlations are calculated and discussed. • The effects of the exchange interactions and crystal field have been studied. • Reentrant phenomena and compensation behaviors have been found.

  13. 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.

  14. Population Structure and Growth of the Threatened Pen Shell, Pinna rudis (Linnaeus, 1758 in a Western Mediterranean Marine Protected Area

    Directory of Open Access Journals (Sweden)

    E. NEBOT COLOMER

    2016-11-01

    Full Text Available Coastal ecosystems are being extensively degraded by human activities. Benthic, slow-growing and long-lived species are highly vulnerable to these impacts. Marine protected areas might avoid biodiversity losses through habitat protection. The pen shell Pinna rudis is a protected species, but scarce data are available on its ecology and biology. The present study is a comprehensive ecological study encompassing several unknown aspects of the growth and inner record in relation to habitat types, density and size distribution. A total of 418 strip transects were conducted by scuba diving in the Marine Protected Area of Cabrera National Park (39.14° N, 2.96° E, during the summers of 2011, 2012 and 2013. Sampling was conducted across different habitats and depths exploring 152,146.35 m2 in total. Densities varied spatially within the park (from 0 to 6.89 ind./100 m2 corresponding to a wide range of sizes and ages. Most pen shells were patchily distributed and mainly concentrated in caves. Two hotspots with high densities represent the highest densities ever recorded worldwide, showing a possible link to high larval accumulation and settlement. The population size structure showed a unimodal distribution with shell width ranging from 6.2 to 25.0 cm, with an average shell width of 16.0 ± 3.4 cm. The absolute growth was asymptotic, with a maximum age and length of 28-31 years and 45 cm, respectively. This study on the biology and ecology of a well-established population of Pinna rudis in the Western Mediterranean could set a baseline for the conservation of this species in other areas.

  15. Spectral element modelling of wave propagation in isotropic and anisotropic shell-structures including different types of damage

    International Nuclear Information System (INIS)

    Schulte, R T; Fritzen, C-P; Moll, J

    2010-01-01

    During the last decades, guided waves have shown great potential for Structural Health Monitoring (SHM) applications. These waves can be excited and sensed by piezoelectric elements that can be permanently attached onto a structure offering online monitoring capability. However, the setup of wave based SHM systems for complex structures may be very difficult and time consuming. For that reason there is a growing demand for efficient simulation tools providing the opportunity to design wave based SHM systems in a virtual environment. As usually high frequency waves are used, the associated short wavelength leads to the necessity of a very dense mesh, which makes conventional finite elements not well suited for this purpose. Therefore in this contribution a flat shell spectral element approach is presented. By including electromechanical coupling a SHM system can be simulated entirely from actuator voltage to sensor voltage. Besides a comparison to measured data for anisotropic materials including delamination, a numerical example of a more complex, stiffened shell structure with debonding is presented.

  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. An ultrasonic methodology for in-service inspection of shell weld of core support structure in a sodium cooled fast reactor

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Anish, E-mail: anish@igcar.gov.in; Rajkumar, K.V.; Sharma, Govind K.; Dhayalan, R.; Jayakumar, T.

    2015-02-15

    Highlights: • We demonstrate a novel ultrasonic methodology for in-service inspection of shell weld of core support structure in a sodium cooled fast breeder reactor. • The methodology comprises of the inspection of shell weld immersed in sodium from the outside surface of the main vessel using ultrasonic guided wave. • The formation and propagation of guided wave modes are validated by finite element simulation of the inspection methodology. • A defect down to 20% of 30 mm thick wall (∼6 mm) in the shell weld can be detected reliably using the developed methodology. - Abstract: The paper presents a novel ultrasonic methodology developed for in-service inspection (ISI) of shell weld of core support structure of main vessel of 500 MWe prototype fast breeder reactor (PFBR). The methodology comprises of the inspection of shell weld immersed in sodium from the outsider surface of the main vessel using a normal beam longitudinal wave ultrasonic transducer. Because of the presence of curvature in the knuckle region of the main vessel, the normal beam longitudinal wave enters the support shell plate at an angle and forms the guided waves by mode conversion and multiple reflections from the boundaries of the shell plate. Hence, this methodology can be used to detect defects in the shell weld of the core support structure. The successful demonstration of the methodology on a mock-up sector made of stainless steel indicated that an artificial defect down to 20% of 30 mm thick wall (∼6 mm) in the shell weld can be detected reliably.

  18. Intrinsic Ge nanowire nonvolatile memory based on a simple core–shell structure

    International Nuclear Information System (INIS)

    Chen, Wen-Hua; Liu, Chang-Hai; Li, Qin-Liang; Sun, Qi-Jun; Liu, Jie; Gao, Xu; Sun, Xuhui; Wang, Sui-Dong

    2014-01-01

    Intrinsic Ge nanowires (NWs) with a Ge core covered by a thick Ge oxide shell are utilized to achieve nanoscale field-effect transistor nonvolatile memories, which show a large memory window and a high ON/OFF ratio with good retention. The retainable surface charge trapping is considered to be responsible for the memory effect, and the Ge oxide shell plays a key role as the insulating tunneling dielectric which must be thick enough to prevent stored surface charges from leaking out. Annealing the device in air is demonstrated to be a simple and effective way to attain thick Ge oxide on the Ge NW surface, and the Ge-NW-based memory corresponding to thick Ge oxide exhibits a much better retention capability compared with the case of thin Ge oxide. (paper)

  19. Shell structure and level migrations in zinc studied using collinear laser spectroscopy

    CERN Multimedia

    Tungate, G; De rydt, M A E; Flanagan, K; Rajabali, M M; Hammen, M; Blaum, K; Froemmgen, N E; Kowalska, M; Campbell, P; Neugart, R; Kreim, K D; Stroke, H H; Krieger, A R; Procter, T J

    We propose to perform collinear laser spectroscopy of zinc isotopes to measure the nuclear spin, magnetic dipole moment, electric quadrupole moment and mean-square charge radius. The yield database indicates that measurements of the isotopes $^{60-81}$Zn will be feasible. These measurements will cross the N = 50 shell closure and provide nuclear moments in a region where an inversion of ground-state spin has been identified in neighbouring chains.

  20. Structures of $p$-shell double-$\\Lambda$ hypernuclei studied with microscopic cluster models

    OpenAIRE

    Kanada-En'yo, Yoshiko

    2018-01-01

    $0s$-orbit $\\Lambda$ states in $p$-shell double-$\\Lambda$ hypernuclei ($^{\\ \\,A}_{\\Lambda\\Lambda}Z$), $^{\\ \\,8}_{\\Lambda\\Lambda}\\textrm{Li}$, $^{\\ \\,9}_{\\Lambda\\Lambda}\\textrm{Li}$, $^{10,11,12}_{\\ \\ \\ \\ \\ \\Lambda\\Lambda}\\textrm{Be}$, $^{12,13}_{\\ \\ \\Lambda\\Lambda}\\textrm{B}$, and $^{\\,14}_{\\Lambda\\Lambda}\\textrm{C}$ are investigated. Microscopic cluster models are applied to core nuclear part and a potential model is adopted for $\\Lambda$ particles. The $\\Lambda$-core potential is a folding ...

  1. A comparison study on the performance of lower order solid finite element for elastic analysis of plate and shell structures

    International Nuclear Information System (INIS)

    Lee, Young Jung; Lee, Sang Jin; Choun, Young Sun; Seo, Jeong Moon

    2003-05-01

    The objective of this research is to assess the performance of lower order solid finite elements which will be ultimately applied into the safety analysis of nuclear containment building. For the safety analysis of large structures such as nuclear containment building, efficient lower order finite element is necessarily required to calculate the structural response of containment building with low computational cost. In this study, the state of the art formulations of lower order solid finite element are throughly reviewed and the best possible solid finite element is adopted into the development of nuclear containment analysis system. Three 8-node solid finite elements based on standard strain-displacement relationship, B-bar method and EAS method are implemented as computer modules and completely tested with various plate and shell structures. The present results can be directly applied into the analysis code development for general reinforced concrete structures

  2. Structure and expression of an unusually acidic matrix protein of pearl oyster shells

    International Nuclear Information System (INIS)

    Tsukamoto, Daiki; Sarashina, Isao; Endo, Kazuyoshi

    2004-01-01

    We report identification and characterization of the unusually acidic molluscan shell matrix protein Aspein, which may have important roles in calcium carbonate biomineralization. The Aspein gene (aspein) encodes a sequence of 413 amino acids, including a high proportion of Asp (60.4%), Gly (16.0%), and Ser (13.2%), and the predicted isoelectric point is 1.45; this is the most acidic of all the molluscan shell matrix proteins sequenced so far, or probably even of all known proteins on earth. The main body of Aspein is occupied by (Asp) 2-10 sequences punctuated with Ser-Gly dipeptides. RT-PCR demonstrated that the transcript of aspein is expressed at the outer edge of the mantle, corresponding to the calcitic prismatic layer, but not at the inner part of the mantle, corresponding to the aragonitic nacreous layer. Our findings and previous in vitro experiments taken together suggest that Aspein is responsible for directed formation of calcite in the shell of the pearl oyster Pinctada fucata

  3. 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.

  4. 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

  5. Electrical Conductivity of Ni-YSZ Anode for SOFCs According to the Ni Powder Size Variations in Core-shell Structure

    International Nuclear Information System (INIS)

    Kang, Young Jin; Jung, Sung-Hun; An, Yong-Tae; Choi, Byung-Hyun; Ji, Mi-Jung

    2015-01-01

    Ni-YSZ (Y_2O_3-stabilized ZrO_2) core-shell structures were prepared by a high-speed mixing method, starting from Ni particles of three different average sizes of 0.2, 0.4, and 1.8 μm. The Ni-YSZ core-shell structures prepared using Ni particles of size 0.2, 0.4, and 1.8 μm exhibited dense core, porous core, and random-morphology core, respectively. Subsequently, nano structured cermet anodes were fabricated using the prepared Ni-YSZ core-shell powders. During the formation of cermet, the heat treatment of Ni-YSZ core-shell powder results in the eruption of Ni core out of the YSZ shell layers, thereby facilitating the formation of nano structured Ni-YSZ cermet. Systematic studies indicated that the morphology and electrical conductivity of the prepared Ni-YSZ core-shell powders and the cermet anode varied, depending on the initial particle size of the Ni particles. Of the different samples prepared in this study, the Ni-YSZ cermet prepared using Ni particles of size 0.4 μm showed the highest electrical conductivity at 750 ℃.

  6. Electrical Conductivity of Ni-YSZ Anode for SOFCs According to the Ni Powder Size Variations in Core-shell Structure

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Young Jin; Jung, Sung-Hun; An, Yong-Tae; Choi, Byung-Hyun; Ji, Mi-Jung [Korea Institute of Ceramic Engineering and Technology (KICET), Seoul (Korea, Republic of)

    2015-04-15

    Ni-YSZ (Y{sub 2}O{sub 3}-stabilized ZrO{sub 2}) core-shell structures were prepared by a high-speed mixing method, starting from Ni particles of three different average sizes of 0.2, 0.4, and 1.8 μm. The Ni-YSZ core-shell structures prepared using Ni particles of size 0.2, 0.4, and 1.8 μm exhibited dense core, porous core, and random-morphology core, respectively. Subsequently, nano structured cermet anodes were fabricated using the prepared Ni-YSZ core-shell powders. During the formation of cermet, the heat treatment of Ni-YSZ core-shell powder results in the eruption of Ni core out of the YSZ shell layers, thereby facilitating the formation of nano structured Ni-YSZ cermet. Systematic studies indicated that the morphology and electrical conductivity of the prepared Ni-YSZ core-shell powders and the cermet anode varied, depending on the initial particle size of the Ni particles. Of the different samples prepared in this study, the Ni-YSZ cermet prepared using Ni particles of size 0.4 μm showed the highest electrical conductivity at 750 ℃.

  7. HANFORD DOUBLE-SHELL TANK THERMAL and SEISMIC PROJECT-ANSYS BENCHMARK ANALYSIS OF SEISMICALLY INDUCED FLUID-STRUCTURE INTERACTION IN A HANFORD DOUBLE-SHELL PRIMARY TANK

    International Nuclear Information System (INIS)

    MACKEY, T.C.

    2006-01-01

    M and D Professional Services, Inc. (M and D) is under subcontract to Pacific Northwest National Laboratories (PNNL) to perform seismic analysis of the Hanford Site Double-Shell Tanks (DSTs) in support of a project entitled ''Double-Shell Tank (DSV Integrity Project-DST Thermal and Seismic Analyses)''. The overall scope of the project is to complete an up-to-date comprehensive analysis of record of the DST System at Hanford in support of Tri-Party Agreement Milestone M-48-14. The work described herein was performed in support of the seismic analysis of the DSTs. The thermal and operating loads analysis of the DSTs is documented in Rinker et al. (2004). The overall seismic analysis of the DSTs is being performed with the general-purpose finite element code ANSYS. The overall model used for the seismic analysis of the DSTs includes the DST structure, the contained waste, and the surrounding soil. The seismic analysis of the DSTs must address the fluid-structure interaction behavior and sloshing response of the primary tank and contained liquid. ANSYS has demonstrated capabilities for structural analysis, but the capabilities and limitations of ANSYS to perform fluid-structure interaction are less well understood. The purpose of this study is to demonstrate the capabilities and investigate the limitations of ANSYS for performing a fluid-structure interaction analysis of the primary tank and contained waste. To this end, the ANSYS solutions are benchmarked against theoretical solutions appearing in BNL 1995, when such theoretical solutions exist. When theoretical solutions were not available, comparisons were made to theoretical solutions of similar problems and to the results from Dytran simulations. The capabilities and limitations of the finite element code Dytran for performing a fluid-structure interaction analysis of the primary tank and contained waste were explored in a parallel investigation (Abatt 2006). In conjunction with the results of the global ANSYS

  8. Synthesis of porous MnCo2O4microspheres with yolk–shell structure induced by concentration gradient and the effect on their performance in electrochemical energy storage

    DEFF Research Database (Denmark)

    Huang, Guoyong; Yang, Yue; Sun, Hongyu

    2016-01-01

    In this study, novel spherical yolk–shell MnCo2O4 powders with concentration gradient have been synthesized. The porous microspheres with yolk–shell structure (2.00–3.00 μm in average diameter, ∼200 nm in thickness of shell) are built up by irregular nanoparticles attached to each other. It is sh...

  9. 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

  10. Growth control, structure, chemical state, and photoresponse of CuO-CdS core-shell heterostructure nanowires.

    Science.gov (United States)

    El Mel, A A; Buffière, M; Bouts, N; Gautron, E; Tessier, P Y; Henzler, K; Guttmann, P; Konstantinidis, S; Bittencourt, C; Snyders, R

    2013-07-05

    The growth of single-crystal CuO nanowires by thermal annealing of copper thin films in air is studied. We show that the density, length, and diameter of the nanowires can be controlled by tuning the morphology and structure of the copper thin films deposited by DC magnetron sputtering. After identifying the optimal conditions for the growth of CuO nanowires, chemical bath deposition is employed to coat the CuO nanowires with CdS in order to form p-n nanojunction arrays. As revealed by high-resolution TEM analysis, the thickness of the polycrystalline CdS shell increases when decreasing the diameter of the CuO core for a given time of CdS deposition. Near-edge x-ray absorption fine-structure spectroscopy combined with transmission x-ray microscopy allows the chemical analysis of isolated nanowires. The absence of modification in the spectra at the Cu L and O K edges after the deposition of CdS on the CuO nanowires indicates that neither Cd nor S diffuse into the CuO phase. We further demonstrate that the core-shell nanowires exhibit the I-V characteristic of a resistor instead of a diode. The electrical behavior of the device was found to be photosensitive, since increasing the incident light intensity induces an increase in the collected electrical current.

  11. 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.

  12. 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.

  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. Glass transition of poly (methyl methacrylate) filled with nanosilica and core-shell structured silica

    DEFF Research Database (Denmark)

    Song, Yihu; Bu, Jing; Zuo, Min

    2017-01-01

    transition and segmental dynamics of PMMA in the nanocomposites prepared via solution casting was compared. The remarkable depression (≥10 °C) of glass transition temperature (Tg) induced by the incorporation of SiO2 and CS was both observed at low loadings. Here, different mechanisms were responsible...... for the effect of SiO2 and CS on the segmental acceleration of PMMA matrix. The formation of rigid amorphous fraction (RAF) layer around SiO2 with the thickness of 16.4 nm led to the adjacent molecular packing frustration, while the “lubrication” effect of nonwetting interface between the grafted crosslinked......Core-shell (CS) nanocomposite particles with 53.4 wt% cross-linked poly (methyl methacrylate) (PMMA) shell of 11.6 nm in thickness were fabricated via miniemulsion polymerization of methyl methacrylate in the presence of modified nanosilica. The influence of nanosilica and CS nanoparticles on glass...

  15. On-shell structures of MHV amplitudes beyond the planar limit

    Energy Technology Data Exchange (ETDEWEB)

    Arkani-Hamed, Nima [School of Natural Sciences, Institute for Advanced Study,Princeton, NJ (United States); Bourjaily, Jacob L. [Niels Bohr International Academy and Discovery Center,Copenhagen (Denmark); Cachazo, Freddy [Perimeter Institute for Theoretical Physics,Waterloo, Ontario (Canada); Postnikov, Alexander [Department of Mathematics, Massachusetts Institute of Technology,Cambridge, MA (United States); Trnka, Jaroslav [Walter Burke Institute for Theoretical Physics, California Institute of Technology,Pasadena, CA (United States)

    2015-06-25

    We initiate an exploration of on-shell functions in N = 4 SYM beyond the planar limit by providing compact, combinatorial expressions for all leading singularities of MHV amplitudes and showing that they can always be expressed as a positive sum of differently ordered Parke-Taylor tree amplitudes. This is understood in terms of an extended notion of positivity in G(2,n), the Grassmannian of 2-planes in n dimensions: a single on-shell diagram can be associated with many different “positive' regions, of which the familiar G{sub +}(2,n) associated with planar diagrams is just one example. The decomposition into Parke-Taylor factors is simply a “triangulation' of these extended positive regions. The U(1) decoupling and Kleiss-Kuijf (KK) relations satisfied by the Parke-Taylor amplitudes also follow naturally from this geometric picture. These results suggest that non-planar MHV amplitudes in N = 4 SYM at all loop orders can be expressed as a sum of polylogarithms weighted by color factors and (unordered) Parke-Taylor amplitudes.

  16. 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.

  17. 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.

  18. 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}.

  19. Progressive buckling analysis for a cylindrical shell structure with the free edge subjected to moving thermal cycles

    International Nuclear Information System (INIS)

    Koo, Gyeong-Hoi; Lee, Jae-Han

    2004-01-01

    In the KALIMER (Korea Advanced Liquid Metal Reactor) design, the reactor baffle structure is adopted to prevent the hot pool sodium from directly contacting the reactor vessel and to guide the hot sodium overflow in severe transient operating conditions. The parts in the vicinity of the hot pool free surface region could be repeatedly subjected to a moving axial temperature gradient and this might result in thermal ratcheting deformation. In this paper, the progressive thermal buckling behaviour following thermal ratcheting due to the moving axial temperature gradients in a cylindrical shell structure with an open free edge is investigated using numerical inelastic analysis with Chaboche's model. To do this, the analyses of the moving temperature distribution are carried out with a simple model and the severe moving axial temperature gradients are assumed to be sufficient for the evolution of thermal ratcheting

  20. Scalable Synthesis of Triple-Core-Shell Nanostructures of TiO2 @MnO2 @C for High Performance Supercapacitors Using Structure-Guided Combustion Waves.

    Science.gov (United States)

    Shin, Dongjoon; Shin, Jungho; Yeo, Taehan; Hwang, Hayoung; Park, Seonghyun; Choi, Wonjoon

    2018-03-01

    Core-shell nanostructures of metal oxides and carbon-based materials have emerged as outstanding electrode materials for supercapacitors and batteries. However, their synthesis requires complex procedures that incur high costs and long processing times. Herein, a new route is proposed for synthesizing triple-core-shell nanoparticles of TiO 2 @MnO 2 @C using structure-guided combustion waves (SGCWs), which originate from incomplete combustion inside chemical-fuel-wrapped nanostructures, and their application in supercapacitor electrodes. SGCWs transform TiO 2 to TiO 2 @C and TiO 2 @MnO 2 to TiO 2 @MnO 2 @C via the incompletely combusted carbonaceous fuels under an open-air atmosphere, in seconds. The synthesized carbon layers act as templates for MnO 2 shells in TiO 2 @C and organic shells of TiO 2 @MnO 2 @C. The TiO 2 @MnO 2 @C-based electrodes exhibit a greater specific capacitance (488 F g -1 at 5 mV s -1 ) and capacitance retention (97.4% after 10 000 cycles at 1.0 V s -1 ), while the absence of MnO 2 and carbon shells reveals a severe degradation in the specific capacitance and capacitance retention. Because the core-TiO 2 nanoparticles and carbon shell prevent the deformation of the inner and outer sides of the MnO 2 shell, the nanostructures of the TiO 2 @MnO 2 @C are preserved despite the long-term cycling, giving the superior performance. This SGCW-driven fabrication enables the scalable synthesis of multiple-core-shell structures applicable to diverse electrochemical applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. [Adsorption of Cu on Core-shell Structured Magnetic Particles: Relationship Between Adsorption Performance and Surface Properties].

    Science.gov (United States)

    Li, Qiu-mei; Chen, Jing; Li, Hai-ning; Zhang, Xiao-lei; Zhang, Gao-sheng

    2015-12-01

    In order to reveal the relationship between the adsorption performance of adsorbents and their compositions, structure, and surface properties, the core-shell structured Fe₃O₄/MnO2 and Fe-Mn/Mn₂2 magnetic particles were systematically characterized using multiple techniques and their Cu adsorption behaviors as well as mechanism were also investigated in details. It was found that both Fe₃O4 and Fe-Mn had spinel structure and no obvious crystalline phase change was observed after coating with MnO₂. The introduction of Mn might improve the affinity between the core and the shell, and therefore enhanced the amount and distribution uniformity of the MnO₂ coated. Consequently, Fe-Mn/MnO₂ exhibited a higher BET specific surface area and a lower isoelectric point. The results of sorption experiments showed that Fe-Mn had a higher maximal Cu adsorption capacity of 33.7 mg · g⁻¹ at pH 5.5, compared with 17.5 mg · g⁻¹ of Fe₃O4. After coating, the maximal adsorption capacity of Fe-Mn/MnO₂ was increased to 58.2 mg · g⁻¹, which was 2.6 times as high as that of Fe₃O₄/MnO₂ and outperformed the majority of magnetic adsorbents reported in literature. In addition, a specific adsorption of Cu occurred at the surface of Fe₃O₄/MnO₂ or Fe-Mn/MnO₂ through the formation of inner-sphere complexes. In conclusion, the adsorption performance of the magnetic particles was positively related to their compositions, structure, and surface properties.

  2. 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.

  3. Tests results of Nb$_{3}$Sn quadrupole magnets using a shell-based support structure

    CERN Document Server

    Caspi, S

    2009-01-01

    In support of the development of a 90 mm aperture Nb$_{3}$Sn superconducting quadrupole for the US LHC Accelerator Research Program (LARP), test results of five quadrupole magnets are compared. All five assemblies used key and bladder technology to compress and support the coils within an iron yoke and an aluminium shell. The first three models (TQS01a, b, c) used Nb$_{3}$Sn MJR conductor and segmented bronze poles. The last two models (TQS02a, b) used Nb$_{3}$Sn RRP conductor, and segmented titanium alloy (TiAl6V4) poles, with no axial gaps during reaction. This presentation summarizes the magnets performance during assembly, cool-down and excitation and compares measurements with design expectations.

  4. 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.

  5. Fabrication of Cu-Ag core-shell bimetallic superfine powders by eco-friendly reagents and structures characterization

    International Nuclear Information System (INIS)

    Zhao Jun; Zhang Dongming; Zhao Jie

    2011-01-01

    Superfine bimetallic Cu-Ag core-shell powders were synthesized by reduction of copper sulfate pentahydrate and silver nitrate with eco-friendly ascorbic acid as a reducing agent and cyclodextrins as a protective agent in an aqueous system. The influence of Ag/Cu ratio on coatings was investigated. Ag was homogeneously distributed on the surface of Cu particles at a mole ratio of Ag/Cu=1. FE-SEM showed an uniformity of Ag coatings on Cu particles. Antioxidation of Cu particles was improved by increasing Ag/Cu ratio. TEM-EDX and UV-vis spectra also revealed that Cu cores were covered by Ag nanoshells on the whole. The surface composition analysis by XPS indicated that only small parts of Cu atoms in the surface were oxidized. It was noted that the hindrance of cyclodextrins chemisorbed on particles plays an important role in forming high quality and good dispersity Cu-Ag (Cu-Ag) core-shell powders. - Graphical abstract: Mechanism of fabricating Cu-Ag particles with good dispersibility using β-CDs as a protective agent was studied because of its special structure. Highlights: → Green supramolecular β-CD used as a protective agent and ascorbic acid(Vc) as a reducing agent to fabricate Cu-Ag powders. → Particles are monodisperse and the diameter is close to nanoscale(100-150 nm). → Resistance of Cu particles to oxidation was higher. → Formation mechanism explained.

  6. Reinforced PEI/PVdF Multicore-Shell Structure Composite Membranes by Phase Prediction on a Ternary Solution

    Directory of Open Access Journals (Sweden)

    Jihye Chae

    2018-04-01

    Full Text Available To construct a polyetherimide (PEI-reinforced polyvinylidene fluoride (PVdF composite membrane with multicore-shell structure, a ternary solution was prepared and electrospun by single-nozzle electrospinning. A theoretical prediction was made for the feasibility of complete distinction of two phases. The diameters of the membrane fibers and the PEI multi-core fibrils varied with the PEI ratio and the spinning time, respectively. The tensile strength and modulus were improved to 48 MPa and 1.5 GPa, respectively. The shrinkage of the membrane was only 6.6% at 180 °C, at which temperature the commercial PE separator melted down. The reinforcement in mechanical and thermal properties is associated with multiple PEI nanofibrils oriented along the fiber axis. Indeed, the unique morphology of self-assembled multicore-shell fibers plays an important role in their properties. All in all, PEI/PVdF membranes are appropriate for a lithium-ion battery application due to their high mechanical strength, excellent thermal stability, and controllable textural properties.

  7. Improved Solar-Driven Photocatalytic Performance of Highly Crystalline Hydrogenated TiO2 Nanofibers with Core-Shell Structure

    Science.gov (United States)

    Wu, Ming-Chung; Chen, Ching-Hsiang; Huang, Wei-Kang; Hsiao, Kai-Chi; Lin, Ting-Han; Chan, Shun-Hsiang; Wu, Po-Yeh; Lu, Chun-Fu; Chang, Yin-Hsuan; Lin, Tz-Feng; Hsu, Kai-Hsiang; Hsu, Jen-Fu; Lee, Kun-Mu; Shyue, Jing-Jong; Kordás, Krisztián; Su, Wei-Fang

    2017-01-01

    Hydrogenated titanium dioxide has attracted intensive research interests in pollutant removal applications due to its high photocatalytic activity. Herein, we demonstrate hydrogenated TiO2 nanofibers (H:TiO2 NFs) with a core-shell structure prepared by the hydrothermal synthesis and subsequent heat treatment in hydrogen flow. H:TiO2 NFs has excellent solar light absorption and photogenerated charge formation behavior as confirmed by optical absorbance, photo-Kelvin force probe microscopy and photoinduced charge carrier dynamics analyses. Photodegradation of various organic dyes such as methyl orange, rhodamine 6G and brilliant green is shown to take place with significantly higher rates on our novel catalyst than on pristine TiO2 nanofibers and commercial nanoparticle based photocatalytic materials, which is attributed to surface defects (oxygen vacancy and Ti3+ interstitial defect) on the hydrogen treated surface. We propose three properties/mechanisms responsible for the enhanced photocatalytic activity, which are: (1) improved absorbance allowing for increased exciton generation, (2) highly crystalline anatase TiO2 that promotes fast charge transport rate, and (3) decreased charge recombination caused by the nanoscopic Schottky junctions at the interface of pristine core and hydrogenated shell thus promoting long-life surface charges. The developed H:TiO2 NFs can be helpful for future high performance photocatalysts in environmental applications.

  8. 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.

  9. Structural analysis of Hanford's single-shell 241-C-106 tank: A first step toward waste-tank remediation

    International Nuclear Information System (INIS)

    Harris, J.P.; Julyk, L.J.; Marlow, R.S.; Moore, C.J.; Day, J.P.; Dyrness, A.D.; Jagadish, P.; Shulman, J.S.

    1993-10-01

    The buried single-shell waste tank 241-C-106, located at the US Department of Energy's Hanford Site, has been a repository for various liquid radioactive waste materials since its construction in 1943. A first step toward waste tank remediation is demonstrating that remediation activities can be performed safely. Determination of the current structural capacity of this high-heat tank is an important element in this assessment. A structural finite-element model of tank 241-C-106 has been developed to assess the tank's structural integrity with respect to in situ conditions and additional remediation surface loads. To predict structural integrity realistically, the model appropriately addresses two complex issues: (1) surrounding soil-tank interaction associated with thermal expansion cycling and surcharge load distribution and (2) concrete-property degradation and creep resulting from exposure to high temperatures generated by the waste. This paper describes the development of the 241-C-106 structural model, analysis methodology, and tank-specific structural acceptance criteria

  10. Thermoelectric-pyroelectric hybrid energy generation from thermopower waves in core-shell structured carbon nanotube-PZT nanocomposites.

    Science.gov (United States)

    Yeo, Taehan; Hwang, Hayoung; Shin, Dongjoon; Seo, Byungseok; Choi, Wonjoon

    2017-02-10

    There is an urgent need to develop a suitable energy source owing to the rapid development of various innovative devices using micro-nanotechnology. The thermopower wave (TW), which produces a high specific power during the combustion of solid fuel inside micro-nanostructure materials, is a unique energy source for unusual platforms that cannot use conventional energy sources. Here, we report on the significant enhancement of hybrid energy generation of pyroelectrics and thermoelectrics from TWs in carbon nanotube (CNT)-PZT (lead zirconate titanate, P(Z 0.5 -T 0.5 )) composites for the first time. Conventional TWs use only charge carrier transport driven by the temperature gradient along the core materials to produce voltage. In this study, a core-shell structure of CNTs-PZTs was prepared to utilize both the temperature gradient along the core material (thermoelectrics) and the dynamic change in the temperature of the shell structure (pyroelectrics) induced by TWs. The dual mechanism of energy generation in CNT-PZT composites amplified the average peak and duration of the voltage up to 403 mV and 612 ms, respectively, by a factor of 2 and 60 times those for the composites without a PZT layer. Furthermore, dynamic voltage measurements and structural analysis in repetitive TWs confirmed that CNT-PZT composites maintain the original performance in multiple TWs, which improves the reusability of materials. The advanced TWs obtained by the application of a PZT layer as a pyroelectric material contributes to the extension of the usable energy portion as well as the development of TW-based operating devices.

  11. 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

  12. 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.

  13. Synthesis of core-shell hematite (α-Fe2O3) nanoplates: Quantitative analysis of the particle structure and shape, high coercivity and low cytotoxicity

    Science.gov (United States)

    Tadic, Marin; Kopanja, Lazar; Panjan, Matjaz; Kralj, Slavko; Nikodinovic-Runic, Jasmina; Stojanovic, Zoran

    2017-05-01

    Hematite core-shell nanoparticles with plate-like morphology were synthesized using a one-step hydrothermal synthesis. An XRPD analysis indicates that the sample consist of single-phase α-Fe2O3 nanoparticles. SEM and TEM measurements show that the hematite sample is composed of uniform core-shell nanoplates with 10-20 nm thickness, 80-100 nm landscape dimensions (aspect ratio ∼5) and 3-4 nm thickness of the surface shells. We used computational methods for the quantitative analysis of the core-shell particle structure and circularity shape descriptor for the quantitative shape analysis of the nanoparticles from TEM micrographs. The calculated results indicated that a percentage of the shell area in the nanoparticle area (share [%]) is significant. The determined values of circularity in the perpendicular and oblique perspective clearly show shape anisotropy of the nanoplates. The magnetic properties revealed the ferromagnetic-like properties at room temperature with high coercivity HC = 2340 Oe, pointing to the shape and surface effects. These results signify core-shell hematite nanoparticles' for practical applications in magnetic devices. The synthesized hematite plate-like nanoparticles exhibit low cytotoxicity levels on the human lung fibroblasts (MRC5) cell line demonstrating the safe use of these nanoparticles for biomedical applications.

  14. 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

  15. Shell structure in the vicinity of the doubly magic {sup 100}Sn via Coulomb excitation at PreSPEC

    Energy Technology Data Exchange (ETDEWEB)

    Guastalla, Giulia

    2014-11-17

    The PreSPEC setup in combination with the high intensity primary beams available at GSI provided unique opportunities for the key nuclear structure studies on exotic nuclei. The experiment performed on the neutron deficient {sup 104}Sn aimed to deduce the reduced transition probability of the first excited 2{sup +} state quantified by the B(E2; 0{sup +} → 2{sup +}) value. This result is the central point in the discussion of the evolution of nuclear structure in proximity of the doubly magic nucleus {sup 100}Sn. As {sup 100}Sn is not yet accessible for such measurements, a series of experiments have been performed for neutron-deficient Sn isotopes over the past few years. These data showed excessive experimental B(E2) strength compared to shell model calculations below neutron number N=64 and they are therefore not excluding a constant or even increasing collectivity below {sup 106}Sn. Hence, the measurement of the B(E2) value in the next even-even isotope toward {sup 100}Sn, i.e. {sup 104}Sn, was a crucial step to verify the robustness of the shell gap of {sup 100}Sn. Moreover, {sup 104}Sn is the heaviest isotope of the Sn isotopic chain for which a shell model calculation without significant truncation of the valence space can be performed and therefore with this experimental value the validity of Large Scale Shell Model (LSSM) calculations could be tested. As a main result of the experiment a B(E2) value corresponding to 0.10(4) e{sup 2}b{sup 2} has been extracted for {sup 104}Sn. The experimental value showed a very good agreement with the predicted one and, despite the large error bar, it clearly established a downward trend of the B(E2) values of the Sn isotopic chain toward A=100. This implied enhanced stability of the N = Z = 50 shell closure against ph-excited quadrupole modes. However, an experiment of this kind is very challenging for several reasons. First, {sup 104}Sn lies in proximity of the proton drip line and has therefore a small production

  16. Form and formation of flares and parabolae based on new observations of the internal shell structure in lytoceratid and perisphinctid ammonoids

    Directory of Open Access Journals (Sweden)

    Gregor Radtke

    2016-08-01

    Full Text Available The ultrastructure of pristine shells of Jurassic and Cretaceous lytoceratid and perisphinctid ammonoids indicates that flares and parabolae represent homologous structures. Both mark an interruption of shell growth. We dismiss earlier interpretations of parabolae as actual aperture, relics of resorbed apophyses or superstructure of the musculature associated to a semi-internal shell. Instead we propose an episodic growth model including several growth stops at the aperture during the formation of a frill-like aperture for parabolae and flares. Such an aperture is composed of the outer prismatic layer, the nacreous layer and an apertural prismatic coating. Here, we observed the apertural prismatic coating for the first time as an integral part of flares and parabolae. The apertural prismatic coating covers only the inner surface of the frill and was secreted by a permanent mantle cover indicating a prolonged period without the production of new shell material. Parabolae differ from flares by their general shape and the presence of ventro-lateral parabolic notches and nodes. The notches were formed by folding of the frill and had the potential to form semi-open spines. The corresponding parabolic nodes are caused by an outward swelling of the shell-secreting mantle tissue producing new shell material at the position of the folding. New shell material that belongs to the conch tube is attached to the base of flares and parabolae after withdrawal of the mantle edge representing the continuation of shell growth. Usually, the frilled aperture associated with flares and parabolae were removed during lifetime. This study reports on flares in Argonauticeras for the first time. In this genus they are typically associated with varices.

  17. 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.

  18. An AgI@g-C3N4 hybrid core@shell structure: Stable and enhanced photocatalytic degradation

    Science.gov (United States)

    Liu, Li; Qi, Yuehong; Yang, Jinyi; Cui, Wenquan; Li, Xingang; Zhang, Zisheng

    2015-12-01

    A novel visible-light-active material AgI@g-C3N4 was prepared by ultrasonication/chemisorption method. The core@shell structure AgI@g-C3N4 catalyst showed high efficiency for the degradation of MB under visible light irradiation (λ > 420 nm). Nearly 96.5% of MB was degraded after 120 min of irradiation in the presence of the AgI@g-C3N4 photocatalyst. Superior stability was also observed in the cyclic runs indicating that the as prepared hybrid composite is highly desirable for the remediation of organic contaminated wastewaters. The improved photocatalytic performance is due to synergistic effects at the interface of AgI and g-C3N4 which can effectively accelerate the charge separation and reinforce the photostability of hybrid composite. The possible mechanism for the photocatalytic activity of AgI@g-C3N4 was tentatively proposed.

  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. 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.

  1. Optimization of wall thickness and lay-up for the shell-like composite structure loaded by non-uniform pressure field

    Science.gov (United States)

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

    2017-01-01

    The glass/carbon fiber composites are widely used in the design of various aircraft and rotorcraft components such as fairings and cowlings, which have predominantly a shell-like geometry and are made of quasi-isotropic laminates. The main requirements to such the composite parts are the specified mechanical stiffness to withstand the non-uniform air pressure at the different flight conditions and reduce a level of noise caused by the airflow-induced vibrations at the constrained weight of the part. The main objective of present study is the optimization of wall thickness and lay-up of composite shell-like cowling. The present approach assumes conversion of the CAD model of the cowling surface to finite element (FE) representation, then its wind tunnel testing simulation at the different orientation of airflow to find the most stressed mode of flight. 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. A wall thickness of the shell had to change over its surface to minimize the objective at the constrained weight. We used a parameterization of the problem that assumes an initiation of auxiliary sphere with varied radius and coordinates of the center, which were the design variables. Curve that formed by the intersection of the shell with sphere defined boundary of area, which should be reinforced by local thickening the shell wall. To eliminate a local stress concentration this increment was defined as the smooth function defined on the shell surface. As a result of structural optimization we obtained the thickness of shell's wall distribution, which then was used to design the draping and lay-up of composite prepreg layers. The global strain energy in the optimized cowling was reduced in2

  2. Effects of Alloying Elements on the Formation of Core-Shell-Structured Reinforcing Particles during Heating of Al–Ti Powder Compacts

    Science.gov (United States)

    Chen, Tijun; Gao, Min; Tong, Yunqi

    2018-01-01

    To prepare core-shell-structured Ti@compound particle (Ti@compoundp) reinforced Al matrix composite via powder thixoforming, the effects of alloying elements, such as Si, Cu, Mg, and Zn, on the reaction between Ti powders and Al melt, and the microstructure of the resulting reinforcements were investigated during heating of powder compacts at 993 K (720 °C). Simultaneously, the situations of the reinforcing particles in the corresponding semisolid compacts were also studied. Both thermodynamic analysis and experiment results all indicate that Si participated in the reaction and promoted the formation of Al–Ti–Si ternary compounds, while Cu, Mg, and Zn did not take part in the reaction and facilitated Al3Ti phase to form to different degrees. The first-formed Al–Ti–Si ternary compound was τ1 phase, and then it gradually transformed into (Al,Si)3Ti phase. The proportion and existing time of τ1 phase all increased as the Si content increased. In contrast, Mg had the largest, Cu had the least, and Si and Zn had an equivalent middle effect on accelerating the reaction. The thicker the reaction shell was, the larger the stress generated in the shell was, and thus the looser the shell microstructure was. The stress generated in (Al,Si)3Ti phase was larger than that in τ1 phase, but smaller than that in Al3Ti phase. So, the shells in the Al–Ti–Si system were more compact than those in the other systems, and Si element was beneficial to obtain thick and compact compound shells. Most of the above results were consistent to those in the semisolid state ones except the product phase constituents in the Al–Ti–Mg system and the reaction rate in the Al–Ti–Zn system. More importantly, the desirable core-shell structured Ti@compoundp was only achieved in the semisolid Al–Ti–Si system. PMID:29342946

  3. Effects of Alloying Elements on the Formation of Core-Shell-Structured Reinforcing Particles during Heating of Al-Ti Powder Compacts.

    Science.gov (United States)

    Chen, Tijun; Gao, Min; Tong, Yunqi

    2018-01-15

    To prepare core-shell-structured Ti@compound particle (Ti@compound p ) reinforced Al matrix composite via powder thixoforming, the effects of alloying elements, such as Si, Cu, Mg, and Zn, on the reaction between Ti powders and Al melt, and the microstructure of the resulting reinforcements were investigated during heating of powder compacts at 993 K (720 °C). Simultaneously, the situations of the reinforcing particles in the corresponding semisolid compacts were also studied. Both thermodynamic analysis and experiment results all indicate that Si participated in the reaction and promoted the formation of Al-Ti-Si ternary compounds, while Cu, Mg, and Zn did not take part in the reaction and facilitated Al₃Ti phase to form to different degrees. The first-formed Al-Ti-Si ternary compound was τ1 phase, and then it gradually transformed into (Al,Si)₃Ti phase. The proportion and existing time of τ1 phase all increased as the Si content increased. In contrast, Mg had the largest, Cu had the least, and Si and Zn had an equivalent middle effect on accelerating the reaction. The thicker the reaction shell was, the larger the stress generated in the shell was, and thus the looser the shell microstructure was. The stress generated in (Al,Si)₃Ti phase was larger than that in τ1 phase, but smaller than that in Al₃Ti phase. So, the shells in the Al-Ti-Si system were more compact than those in the other systems, and Si element was beneficial to obtain thick and compact compound shells. Most of the above results were consistent to those in the semisolid state ones except the product phase constituents in the Al-Ti-Mg system and the reaction rate in the Al-Ti-Zn system. More importantly, the desirable core-shell structured Ti@compound p was only achieved in the semisolid Al-Ti-Si system.

  4. 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.

  5. Morphogenesis of the turtle shell: the development of a novel structure in tetrapod evolution.

    Science.gov (United States)

    Gilbert, S F; Loredo, G A; Brukman, A; Burke, A C

    2001-01-01

    The turtle shell is an evolutionary novelty that is synapomorphic for chelonians. The carapace is initiated by the entrapment of the ribs by the carapacial ridge (CR), a lateral bulge of the dorsal ectoderm and dermal mesoderm. The mechanisms by which the CR is initiated, the ribs entrapped and the dorsal dermis ossified, remains unknown. Similarly, the formation of the plastron remains unexplained. Here, we present a series of anatomical investigations into plastron and carapace formation in the red-eared slider, Trachemys scripta, and the snapping turtle, Chelydra serpentina. We document the entrapment of the ribs by the CR and the formation of the plastron and carapacial bones by intramembranous ossification. We note the formation of the ossification centers around each rib, which suggest that the rib is organizing dermal ossification by secreting paracrine factors. The nuchal ossification center is complex and appears to involve multiple bone-forming regions. Individual ossification centers at the periphery of the carapace form the peripheral and pygial bones. The intramembranous ossification of the plastron proceeds from nine distinct ossification centers, and there appear to be interactions between the spicules of apposing centers as they draw near each other.

  6. Highly selective and sensitive methanol gas sensor based on molecular imprinted silver-doped LaFeO3 core-shell and cage structures

    Science.gov (United States)

    Rong, Qian; Zhang, Yumin; Lv, Tianping; Shen, Kaiyuan; Zi, Baoye; Zhu, Zhongqi; Zhang, Jin; Liu, Qingju

    2018-04-01

    Silver-doped LaFeO3 molecularly imprinted polymers (SLMIPs) were synthesized by a sol-gel method combined with molecularly imprinted technology as precursors. The precursors were then used to prepare SLMIPs cage (SLM-cage) and SLMIPs core-shell (SLM-core-shell) structures by using a carbon sphere as the template and hydrothermal synthesis, respectively. The structures, morphologies, and surface areas of these materials were determined, as well as their gas-sensing properties and related mechanisms. The SLM-cage and SLM-core-shell samples exhibited good responses to methanol gas, with excellent selectivity. The response and optimum working temperature were 16.98 °C and 215 °C, 33.7 °C and 195 °C, respectively, with corresponding response and recovery times of 45 and 50 s (SLM-cage) and 42 and 57 s (SLM-core-shell) for 5 ppm methanol gas. Notably, the SLM-cage and SLM-core-shell samples exhibited lower responses (≤5 and ≤7, respectively) to other gases, including ethanol, ammonia, benzene, acetone, and toluene. Thus, these materials show potential as practical methanol detectors.

  7. I. Fission Probabilities, Fission Barriers, and Shell Effects. II. Particle Structure Functions

    Energy Technology Data Exchange (ETDEWEB)

    Jing, Kexing [Univ. of California, Berkeley, CA (United States)

    1999-05-01

    In Part I, fission excitation functions of osmium isotopes 185,186, 187, 189 Os produced in 3He +182,183, 184, 186W reactions, and of polonium isotopes 209,210, 211, 212Po produced in 3He/4He + 206, 207, 208Pb reactions, were measured with high precision. These excitation functions have been analyzed in detail based upon the transition state formalism. The fission barriers, and shell effects for the corresponding nuclei are extracted from the detailed analyses. A novel approach has been developed to determine upper limits of the transient time of the fission process. The upper limits are constrained by the fission probabilities of neighboring isotopes. The upper limits for the transient time set with this new method are 15x 10–21 sec and 25x 10–21 sec for 0s and Po compound nuclei, respectively. In Part II, we report on a search for evidence of the optical modulations in the energy spectra of alpha particles emitted from hot compound nuclei. The optical modulations are expected to arise from the ~-particle interaction with the rest of the nucleus as the particle prepares to exit. Some evidence for the modulations has been observed in the alpha spectra measured in the 3He-induced reactions, 3He + natAg in particular. The identification of the modulations involves a technique that subtracts the bulk statistical background from the measured alpha spectra, in order for the modulations to become visible in the residuals. Due to insufficient knowledge of the background spectra, however, the presented evidence should only be regarded as preliminary and tentative.

  8. 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.

  9. Hierarchical core-shell structure of ZnO nanorod@NiO/MoO₂ composite nanosheet arrays for high-performance supercapacitors.

    Science.gov (United States)

    Hou, Sucheng; Zhang, Guanhua; Zeng, Wei; Zhu, Jian; Gong, Feilong; Li, Feng; Duan, Huigao

    2014-08-27

    A hierarchical core-shell structure of ZnO nanorod@NiO/MoO2 composite nanosheet arrays on nickel foam substrate for high-performance supercapacitors was constructed by a two-step solution-based method involving two hydrothermal processes followed by a calcination treatment. Compared to one composed of pure NiO/MoO2 composite nanosheets, the hierarchical core-shell structure electrode displays better pseudocapacitive behaviors in 2 M KOH, including high areal specific capacitance values of 1.18 F cm(-2) at 5 mA cm(-2) and 0.6 F cm(-2) at 30 mA cm(-2) as well as relatively good rate capability at high current densities. Furthermore, it also shows remarkable cycle stability, remaining at 91.7% of the initial value even after 4000 cycles at a current density of 10 mA cm(-2). The enhanced pseudocapacitive behaviors are mainly due to the unique hierarchical core-shell structure and the synergistic effect of combining ZnO nanorod arrays and NiO/MoO2 composite nanosheets. This novel hierarchical core-shell structure shows promise for use in next-generation supercapacitors.

  10. 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.

  11. Room-temperature synthesis of core-shell structured magnetic covalent organic frameworks for efficient enrichment of peptides and simultaneous exclusion of proteins.

    Science.gov (United States)

    Lin, Guo; Gao, Chaohong; Zheng, Qiong; Lei, Zhixian; Geng, Huijuan; Lin, Zian; Yang, Huanghao; Cai, Zongwei

    2017-03-28

    Core-shell structured magnetic covalent organic frameworks (Fe 3 O 4 @COFs) were synthesized via a facile approach at room temperature. Combining the advantages of high porosity, magnetic responsiveness, chemical stability and selectivity, Fe 3 O 4 @COFs can serve as an ideal absorbent for the highly efficient enrichment of peptides and the simultaneous exclusion of proteins from complex biological samples.

  12. Sustainable solid-state strategy to hierarchical core-shell structured Fe 3 O 4 @graphene towards a safer and green sodium ion full battery

    KAUST Repository

    Ding, Xiang; Huang, Xiaobing; Jin, Junling; Ming, Hai; Wang, Limin; Ming, Jun

    2017-01-01

    A sustainable solid-state strategy of SPEX milling is developed to coat metal oxide (e.g., Fe3O4) with tunable layers of graphene, and a new hierarchical core-shell structured Fe3O4@graphene composite is constructed. The presented green process can

  13. Ab initio and shell model studies of structural, thermoelastic and vibrational properties of SnO2 under pressure

    Science.gov (United States)

    Casali, R. A.; Lasave, J.; Caravaca, M. A.; Koval, S.; Ponce, C. A.; Migoni, R. L.

    2013-04-01

    The pressure dependences of the structural, thermoelastic and vibrational properties of SnO2 in its rutile phase are studied, as well as the pressure-induced transition to a CaCl2-type phase. These studies have been performed by means of ab initio (AI) density functional theory calculations using the localized basis code SIESTA. The results are employed to develop a shell model (SM) for application in future studies of nanostructured SnO2. A good agreement of the SM results for the pressure dependences of the above properties with the ones obtained from present and previous AI calculations as well as from experiments is achieved. The transition is characterized by a rotation of the Sn-centered oxygen octahedra around the tetragonal axis through the Sn. This rotation breaks the tetragonal symmetry of the lattice and an orthorhombic distortion appears above the critical pressure Pc. A zone-center phonon of B1g symmetry in the rutile phase involves such rotation and softens on approaching Pc. It becomes an Ag mode which stabilizes with increasing pressure in the CaCl2 phase. This behavior, together with the softening of the shear modulus (C11-C12)/2 related to the orthorhombic distortion, allows a precise determination of a value for Pc. An additional determination is provided by the splitting of the basal plane lattice parameters. Both the AI and the experimentally observed softening of the B1g mode are incomplete, indicating a small discontinuity at the transition. However, all results show continuous changes in volume and lattice parameters, indicating a second-order transition. All these results indicate that there should be sufficient confidence for the future employment of the shell model.

  14. Ab initio and shell model studies of structural, thermoelastic and vibrational properties of SnO2 under pressure

    International Nuclear Information System (INIS)

    Casali, R A; Ponce, C A; Lasave, J; Koval, S; Migoni, R L; Caravaca, M A

    2013-01-01

    The pressure dependences of the structural, thermoelastic and vibrational properties of SnO 2 in its rutile phase are studied, as well as the pressure-induced transition to a CaCl 2 -type phase. These studies have been performed by means of ab initio (AI) density functional theory calculations using the localized basis code SIESTA. The results are employed to develop a shell model (SM) for application in future studies of nanostructured SnO 2 . A good agreement of the SM results for the pressure dependences of the above properties with the ones obtained from present and previous AI calculations as well as from experiments is achieved. The transition is characterized by a rotation of the Sn-centered oxygen octahedra around the tetragonal axis through the Sn. This rotation breaks the tetragonal symmetry of the lattice and an orthorhombic distortion appears above the critical pressure P c . A zone-center phonon of B 1g symmetry in the rutile phase involves such rotation and softens on approaching P c . It becomes an A g mode which stabilizes with increasing pressure in the CaCl 2 phase. This behavior, together with the softening of the shear modulus (C 11 −C 12 )/2 related to the orthorhombic distortion, allows a precise determination of a value for P c . An additional determination is provided by the splitting of the basal plane lattice parameters. Both the AI and the experimentally observed softening of the B 1g mode are incomplete, indicating a small discontinuity at the transition. However, all results show continuous changes in volume and lattice parameters, indicating a second-order transition. All these results indicate that there should be sufficient confidence for the future employment of the shell model. (paper)

  15. 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).

  16. 脉冲 Er:YAG 激光与常规涡轮高速车针治疗楔状缺损的效果比较%The Effect Comparasion between the Pulse Er:YAG Laser and the Conventional Turbine High-speed Dental Bur to the Remedy of Teeth Wedge-shaped Defect

    Institute of Scientific and Technical Information of China (English)

    范伟; 贺慧霞

    2015-01-01

    目的:比较Er:YAG激光与常规涡轮机高速车针治疗楔状缺损的效果。方法收集我院口腔科就诊的、双侧多个同名牙楔状缺损患者85例382颗牙,随机分为激光组和涡轮机组各191牙,其中每位患者每侧至少2颗牙采用激光表面预备,对侧高速涡轮机预备,脉冲照射采用激光剂量为300 mJ,20 Hz间歇操作。涡轮机组采用高速车针制备固位型,自体对照,两组均预备后光固化树脂黏充填。比较两组治疗后1周、1个月、6个月、12个月术后充填物保存率、边缘着色、继发龋等指标,评价其临床治疗效果。结果两组术中疼痛牙齿发生率激光组(16.7%)显著少于涡轮机组(74.8%),差异有统计学意义(P<0.05);术后1周、1个月激光组分别有35牙和12牙出现冷热刺激痛,而涡轮机组发生刺激痛分别为83牙和44牙,两者差异有统计学意义( P<0.05);术后6个月和12个月修复体保存率激光组显著高于涡轮机组,差异有统计学意义( P<0.05);但边缘适合性、边缘着色和继发龋发生率两组差异无统计学意义。结论激光组较涡轮机组在楔状缺损治疗中疼痛发生率低、治疗后疼痛反应轻;修复体保存率高。300 mJ,20 Hz的Er:YAG激光治疗楔状缺损具有无痛、安全、高效的优点。%Objective To compare the effects of Er: YAG laser and conventional high-speed burr in treatment of wedge-shaped tooth defects and to evaluate its applicability and reliability .Methods 382 bilateral multiple teeth with wedge-shaped defects in 85 patients were randomly divided into two groups with 191 teeth in each:laser group and the turbine burr group .At least two teeth of one side in all patients were irradiated by pulsed Er:YAG laser with doses of 300 mj, 20 Hz.Meanwhile, the caries cavities on the contralateral were prepared by high-speed burr .Then the prepared caries defects in both

  17. Tubular House - Form Follows Technology, Concrete Shell Structure with Inner Thermal Insulation

    Science.gov (United States)

    Idem, Robert; Kleczek, Paweł; Pawłowski, Krzysztof; Chudoba, Piotr

    2017-10-01

    The aim of this paper is the theoretical analysis of the possibilities and limitations of using an unconventional technology and the original architectural form stemming from it - the building with external construction and internal insulation. In Central European climatic conditions, the traditional solution for the walls of heated buildings relies on using external thermal insulation. This stems from building physics: it prevents interstitial condensation of water vapour in the wall. Internal insulation is used exceptionally. This is done e.g. in historical buildings undergoing thermal modernization (due to the impossibility of interfering with facade). In such cases, a thermal insulation layer is used on the internal wall surface, along with an additional layer of vapour barrier. The concept of building concerns the intentional usage of an internal insulation. In this case, the construction is a tight external reinforced concrete shell. The architectural form of such building is strongly interrelated with the technology, which was used to build it. The paper presents the essence of this concept in descriptive and drawing form. The basic elements of such building are described (the external construction, the internal insulation and ventilation). As a case study, authors present a project of a residential building along with the description of the applied materials and installation solutions, and the results obtained from thermal, humidity and energetic calculations. The discussion presents the advantages and disadvantages of the proposed concept. The basic advantage of this solution is potentially low building cost. This stems from minimizing the ground works, the simplicity of the joints and the outer finish, as well as from the possibility of prefabrication of the elements. The continuity of the thermal insulation allows to reduce the amount of thermal bridges. The applied technology and form are applicable most of all for small buildings, due to limited

  18. Spatial Resolution of a Wedge Shaped MSGC Module

    CERN Document Server

    Bachmann, Sebastian

    1997-01-01

    A banana shaped closed design MSGC detector module was tested together with silicon detectors and other MSGCs in a 100 GeV muon beam. Despite of an undesirable geometry of the test setup, a spatial resolution below 40 micron m was reached. The efficiency of the module, defined by track reconstruction, shows to be 95,6 percent

  19. Seniority and K-structure of the cranked shell model wave function: Pt. 2

    International Nuclear Information System (INIS)

    Lin Xinwei; Liao Boqin; Tang Xianghong; Wu Chongshi; Zeng Jinyan

    1988-01-01

    The seniority v-structure and the K-structure of the CSM wave function for odd particlernumber system are analysed. For not too high ω (h-bar≤0.5MeV) configurations with v = 1, 3, 5 are dominant for the low-lying bands, while those with v≤7 are negligibly small. Also the K-structure of the low lying bands become very complicated. Calculation shows that the blocking effect is very important for the low-lying bands in low-ω region

  20. Core-Shell Nano structure of a-Fe2O3/Fe3O4: Synthesis and Photo catalysis for Methyl Orange

    International Nuclear Information System (INIS)

    Tian, Y.; Wu, D.; Yu, B.; Jia, X.; Zhan, S.

    2011-01-01

    Fe 3 O 4 nanoparticle was synthesized in the solution involving water and ethanol. Then, a-Fe 2 O 3 shell was produced in situ on the surface of the Fe 3 O 4 nanoparticle by surface oxidation in molten salts, forming α-Fe 2 O 3 /Fe 3 O 4 core-shell nano structure. It was showed that the magnetic properties transformed from ferromagnetism to superparamagnetism after the primary Fe 3 O 4 nanoparticles were oxidized. Furthermore, the obtained a-Fe 2 O 3 /Fe 3 O 4 core-shell nanoparticles were used to photo catalyse solution of methyl orange, and the results revealed that a-Fe 2 O 3 /Fe 3 O 4 nanoparticles were more efficient than the self-prepared α-Fe 2 O 3 nanoparticles. At the same time, the photo catalyzer was recyclable by applying an appropriate magnetic field.

  1. High spin structure of nuclei near N = 50 shell gap and search for high-spin isomers using time stamped data

    International Nuclear Information System (INIS)

    Saha, S.; Palit, R.; Trivedi, T.; Sethi, J.; Joshi, P.K.; Naidu, B.S.; Donthi, R.; Jadhav, S.; Nanal, V.; Pillay, R.G.; Jain, H.C.; Kumar, S.; Biswas, D.C.; Mukherjee, G.; Saha, S.

    2011-01-01

    Information on the high-spin states of nuclei promises to provide stringent test of the interaction of the Hamiltonian used in the calculation due to smaller basis space for high J-values. It is reported in a recent shell model review that no interaction is optimized for the region of interest around N = 50 and Z = 40 shell closure. The detailed spectroscopic information of the medium and high spin states in these nuclei is required to understand the shape transition between spherical and deformed shapes at N =60 as the higher orbitals are filled. Structure of isomers near shell closure carries important information of, for example, the extent of core excitation. In the present work, the spectroscopic study of the high spin states of 89 Zr isotope have been discussed

  2. Benefits of Silica Core-Shell Structures on the Temperature Sensing Properties of Er,Yb:GdVO4 Up-Conversion Nanoparticles.

    Science.gov (United States)

    Savchuk, Oleksandr A; Carvajal, Joan J; Cascales, C; Aguiló, M; Díaz, F

    2016-03-23

    We studied the temperature-dependent luminescence of GdVO4 nanoparticles co-doped with Er(3+) (1 mol %) and Yb(3+) (20 mol %) and determined their thermal sensing properties through the fluorescence intensity ratio (FIR) technique. We also analyzed how a silica coating, in a core-shell structure, affects the temperature sensing properties of this material. Spectra were recorded in the range of biological temperatures (298-343 K). The absolute sensitivity for temperature determination calculated for the core-shell nanoparticles is double the one calculated for bare nanoparticles, achieving a thermal resolution of 0.4 K. Moreover, silica-coated nanoparticles show good dispersibility in different solvents, such as water, DMSO, and methanol. Also, they show good luminescence stability without interactions with solvent molecules. Furthermore, we also observed that the silica coating shell prevents progressive heating of the nanoparticles during prolonged excitation periods with the 980 nm laser, preventing effects on their thermometric applications.

  3. Design aids for stiffened composite shells with cutouts

    CERN Document Server

    Sahoo, Sarmila

    2017-01-01

    This book focuses on the free vibrations of graphite-epoxy laminated composite stiffened shells with cutout both in terms of the natural frequencies and mode shapes. The dynamic analysis of shell structures, which may have complex geometry and arbitrary loading and boundary conditions, is solved efficiently by the finite element method, even including cutouts in shells. The results may be readily used by practicing engineers dealing with stiffened composite shells with cutouts. Several shell forms viz. cylindrical shell, hypar shell, conoidal shell, spherical shell, saddle shell, hyperbolic paraboloidal shell and elliptic paraboloidal shell are considered in the book. The dynamic characteristics of stiffened composite shells with cutout are described in terms of the natural frequency and mode shapes. The size of the cutouts and their positions with respect to the shell centre are varied for different edge constraints of cross-ply and angle-ply laminated composite shells. The effects of these parametric variat...

  4. Ply-based Optimization of Laminated Composite Shell Structures under Manufacturing Constraints

    DEFF Research Database (Denmark)

    Sørensen, Rene; Lund, Erik

    2012-01-01

    This work concerns a new ply-based parameterization for performing simultaneous material selection and topology optimization of fiber reinforced laminated composite structures while ensuring that a series of different manufacturing constraints are fulfilled. The material selection can either...

  5. Core/shell structure NiCo2O4@MnCo2O4 nanofibers fabricated by different temperatures for high-performance supercapacitors

    Science.gov (United States)

    Wang, Qing; Qin, Xuefeng; Jiang, Pengcheng; Dai, Jianfeng; Li, Weixue; Gao, Haoran

    2018-03-01

    Core/shell structure NiCo2O4@MnCo2O4 nanofibers (NiCo2O4@MnCo2O4 NFs) were prepared by a facile co-electrospinning method and heat treatment. The composites annealed at 500 °C have a complete, continuously obvious core/shell structure, and clear interface of composites with good morphology, while annealed at 600 °C were stacked on each other and were unable to sustain three-dimensional network structures and 700 °C calcination have completely lost one-dimensional structure. The core NiCo2O4 is about 70 nm in diameter and the MnCo2O4 shell behaves a thickness about 60 nm. When investigated as an electrode material for supercapacitors, the NiCo2O4@MnCo2O4 NFs annealed at 500 °C exihibited the specific capacitance of 463 F g-1 (0.926 F cm-2) at 1 A g-1, higher than that annealed at 600 °C 362 F g-1, 1 A g-1 (0.724 F cm-2, 1 A g-1) and 700 °C 283 F g-1, 1 A g-1 (0.566 F cm-2, 1 A g-1). These results suggest that core/shell NiCo2O4@MnCo2O4 NFs annealed at 500 °C have formed a good morphology with continuously complete core/shell structure which lead to good properties would be potential electrodes for supercapacitors.

  6. Pearl-necklace structures in core-shell molecular brushes: Experiments, Monte Carlo simulations and self-consistent field modeling

    NARCIS (Netherlands)

    Polotsky, A.; Charlaganov, M.; Xu, Y.P.; Leermakers, F.A.M.; Daoud, M.; Muller, A.H.E.; Dotera, T.; Borisov, O.V.

    2008-01-01

    We present theoretical arguments and experimental evidence for a longitudinal instability in core-shell cylindrical polymer brushes with a solvophobic inner (core) block and a solvophilic outer (shell) block in selective solvents. The two-gradient self-consistent field Scheutjens-Fleer (SCF-SF)

  7. 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.

  8. 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.

  9. 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.

  10. Structural acceptance criteria for the evaulation of existing double-shell waste storage tanks located at the Hanford site, Richland, Washington

    International Nuclear Information System (INIS)

    Julyk, L.J.; Day, A.D.; Dyrness, A.D.; Moore, C.J.; Peterson, W.S.; Scott, M.A.; Shrivastava, H.P.; Sholman, J.S.; Watts, T.N.

    1995-09-01

    The structural acceptance criteria contained herein for the evaluation of existing underground double-shell waste storage tanks located at the Hanford Site is part of the Life Management/Aging Management Program of the Tank Waste Remediation System. The purpose of the overall life management program is to ensure that confinement of the waste is maintained over the required service life of the tanks. Characterization of the present condition of the tanks, understanding and characterization of potential degradation mechanisms, and development of tank structural acceptance criteria based on previous service and projected use are prerequisites to assessing tank integrity, to projecting the length of tank service, and to developing and applying prudent fixes or repairs. The criteria provided herein summarize the requirements for the analysis and structural qualification of the existing double-shell tanks for continued operation. Code reconciliation issues and material degradation under aging conditions are addressed. Although the criteria were developed for double-shell tanks, many of the provisions are equally applicable to single-shell tanks. However, the criteria do not apply to the evaluation of tank appurtenances and buried piping

  11. Modelling the structure and kinematics of the Firework nebula: The nature of the GK Persei nova shell and its jet-like feature

    Science.gov (United States)

    Harvey, E.; Redman, M. P.; Boumis, P.; Akras, S.

    2016-10-01

    Aims: The shaping mechanisms of old nova remnants are probes for several important and unexplained processes, such as dust formation and the structure of evolved star nebulae. To gain a more complete understanding of the dynamics of the GK Per (1901) remnant, an examination of symmetry of the nova shell is explored, followed by a kinematical analysis of the previously detected jet-like feature in the context of the surrounding fossil planetary nebula. Methods: Faint-object high-resolution echelle spectroscopic observations and imaging were undertaken covering the knots which comprise the nova shell and the surrounding nebulosity. New imaging from the Aristarchos telescope in Greece and long-slit spectra from the Manchester Echelle Spectrometer instrument at the San Pedro Mártir observatory in Mexico were obtained, supplemented with archival observations from several other optical telescopes. Position-velocity arrays are produced of the shell, and also individual knots, and are then used for morpho-kinematic modelling with the shape code. The overall structure of the old knotty nova shell of GK Per and the planetary nebula in which it is embedded is then analysed. Results: Evidence is found for the interaction of knots with each other and with a wind component, most likely the periodic fast wind emanating from the central binary system. We find that a cylindrical shell with a lower velocity polar structure gives the best model fit to the spectroscopy and imaging. We show in this work that the previously seen jet-like feature is of low velocity. Conclusions: The individual knots have irregular tail shapes; we propose here that they emanate from episodic winds from ongoing dwarf nova outbursts by the central system. The nova shell is cylindrical, not spherical, and the symmetry axis relates to the inclination of the central binary system. Furthermore, the cylinder axis is aligned with the long axis of the bipolar planetary nebula in which it is embedded. Thus, the

  12. Magnetic and structural investigations on La0.6Sr0.4MnO3 nanostructured manganite: Evidence of a ferrimagnetic shell

    International Nuclear Information System (INIS)

    Andrade, V.M.; Caraballo-Vivas, R.J.; Costas-Soares, T.; Pedro, S.S.; Rocco, D.L.; Reis, M.S.; Campos, A.P.C.; Coelho, A.A.

    2014-01-01

    This paper presents the structural and magnetic properties of La 0.6 Sr 0.4 MnO 3 nanoparticles with sizes from 21 to 106 nm, which have been prepared using the sol–gel method. The reduction of the nanoparticles' size tends to broaden the paramagnetic to ferromagnetic transition, as well as to promote magnetic hysteresis and a remarkable change on the magnetic saturation. In order to better understand the magnetic behavior of those nanoparticles, a simple model based on a ferromagnetic core and a ferrimagnetic shell was considered, where the magnetization was described in terms of the standard mean-field Brillouin function. This model matches the experimental data, leading to conclusion the nanoparticles with size <40nm are single magnetic domain. In addition, the output fitting parameters give information on the Landé factor of the core and shell. - Graphical abstract: Core–shell model: The core has a ferromagnetic character, while the shell is ferrimagnetic. Each one has two sub-lattices (Mn 3+ and Mn 4+ ) that interact through a mean-field (see Eq. (6)). Interactions strength and signals are also represented in this figure. In this figure the arrows (or vectors) represent the magnetic moment of ions Mn 3+ (s=2) and Mn 4+ (s=3/2). βλ's describe the ferromagnetic interaction between Mn 4+ ions into the core (βλ co ) and into the shell (βλ sh ), while αλ's represent ferromagnetic interaction between Mn 3+ ions into the core (αλ co ) and into the shell (αλ sh ). The −λ sh and +λ co co are associated to the mean field parameter of interaction between Mn 3+ and Mn 4+ sub-lattices in the shell (ferrimagnetic, negative sign) and core (ferromagnetic, positive sign), respectively. - Highlights: • Evidences of ferromagnetic shell in La 0.6 Sr 0.4 MnO 3 ferromagnetic nanoparticles. • Core(ferromagnetic)–shell(ferromagnetic) model for nanostructured manganite. • Sol–gel method was successfully used to obtain nanostructured

  13. 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

  14. 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.

  15. The CEASEMT system (Calculation and Analysis of Structures in Mechanics and Thermics). Program TRICO. Analysis of tridimensionnal structures made of shells and beams. Statics - Dynamics - Elasticity - Plasticity - Collapse - Large displacements

    International Nuclear Information System (INIS)

    Hoffmann, Alain; Jeanpierre, Francoise.

    1976-01-01

    The TRICO subroutine of the CEASEMT system is especially intended for elastic or plastic computation of structures made of thin shells and beams. TRICO involves the finite element method for shells and beams, and is also suitable for a dynamic structural analysis: eigenmode and eigenfrequency analysis, and analysis of the response to various sinusoidal excitations, or time dependent elastic and plastic loading. Structures may have various shapes composed of a number of materials. Data are distributed between different optional commands having a precise physical sense, corresponding to a sequential program. A dynamic memory control provides the adaptation of the size of the program to that of the problem to be solved [fr

  16. Modelling loading and break-up of RC structure due to internal explosion of fragmenting shells

    NARCIS (Netherlands)

    Weerheijm, J.; Stolz, A.; Riedel, W.; Mediavilla Varas, J.

    2012-01-01

    The Klotz Group (KG), an international group of experts on explosion safety, investigates the debris throw hazard associated with the accidental detonation of ammunition in reinforced concrete (RC-) structures. Experiments are combined with engineering models but also with results of advanced

  17. Modelling loading and break-up of RC structure due to internal explosion of fragmenting shells

    NARCIS (Netherlands)

    Weerheijm, J.; Stolz, A.; Riedel, W.; Mediavilla, J.

    2012-01-01

    The Klotz Group (KG), an mtemational group of experts on explosion safety, investigates the debris throw hazard associated with the accidental detonation of ammunition in reinforced concrete (RC-) structures. Experiments are combined with engineering models but also with results of advanced

  18. 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.

  19. 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

  20. Wrinkling of Pressurized Elastic Shells

    KAUST Repository

    Vella, Dominic

    2011-10-01

    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 are subject to a wrinkling instability. We study wrinkling in depth, presenting scaling laws for the critical indentation at which wrinkling occurs and the number of wrinkles formed in terms of the internal pressurization and material properties of the shell. These results are validated by numerical simulations. We show that the evolution of the wrinkle length with increasing indentation can be understood for highly pressurized shells from membrane theory. These results suggest that the position and number of wrinkles may be used in combination to give simple methods for the estimation of the mechanical properties of highly pressurized shells. © 2011 American Physical Society.

  1. 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.

  2. 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.

  3. Structural analysis and evaluation of a mixer pump in a double-shell tank at the Hanford Site

    International Nuclear Information System (INIS)

    Rezvani, M.A.; Strehlow, J.P.; Baliga, R.

    1993-01-01

    The double-shell waste tank 241-SY-101 is a 1,000,000 gallon tank used to store radioactive waste at the Hanford Site near Richland, Washington. With time the waste has formed two layers of sludge, a convective and a nonconvective layer. In addition, a crust has formed over the surface of the waste, isolating the convective layer from the vapor space. Ongoing reactions in the waste cause a buildup of hydrogen molecules that become trapped within the nonconvective layer and under the crust. Over time, this hydrogen buildup increases pressure on the crust from beneath. Every 100 to 140 days, the pressure is released when the crust lifts upward in what is called a waste rollover. To prevent the release of a large volume of hydrogen to the vapor space, a mixer pump has been designed to be installed in the tank to circulate the waste and reduce or prevent the hydrogen buildup. The structural analysis and evaluation designed as part of the hydrogen mitigation test process and presented herein addresses the response of the mixer pump and the tank dome resulting from expected operational and design loads. The loads include deadweight, waste rollover, asymmetric thrust, and pump vibration, as well as seismic loads. The seismically induced loads take into consideration both the convective and the impulsive effects of the waste-filled tank. The structural evaluations were performed in accordance with applicable national codes and standards. The qualification of the mixer pump required the design of a unique mounting assembly to transfer the loads from the pump to the surrounding soil without overstressing the structural components such as the dome penetration riser. Also, special consideration was given to minimize the additional stresses in the already stressed concrete tank dome

  4. Core–Shell Structure and Aggregation Number of Micelles Composed of Amphiphilic Block Copolymers and Amphiphilic Heterografted Polymer Brushes Determined by Small-Angle X-ray Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Szymusiak, Magdalena; Kalkowski, Joseph; Luo, Hanying; Donovan, Alexander J.; Zhang, Pin; Liu, Chang; Shang, Weifeng; Irving, Thomas; Herrera-Alonso, Margarita; Liu, Ying (JHU); (IIT); (UIC)

    2017-08-31

    A large group of functional nanomaterials employed in biomedical applications, including targeted drug delivery, relies on amphiphilic polymers to encapsulate therapeutic payloads via self-assembly processes. Knowledge of the micelle structures will provide critical insights into design of polymeric drug delivery systems. Core–shell micelles composed of linear diblock copolymers poly(ethylene glycol)-b-poly(caprolactone) (PEG-b-PCL), poly(ethylene oxide)-b-poly(lactic acid) (PEG-b-PLA), as well as a heterografted brush consisting of a poly(glycidyl methacrylate) backbone with PEG and PLA branches (PGMA-g-PEG/PLA) were characterized by dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS) measurements to gain structural information regarding the particle morphology, core–shell size, and aggregation number. The structural information at this quasi-equilibrium state can also be used as a reference when studying the kinetics of polymer micellization.

  5. Core–Shell Structure and Aggregation Number of Micelles Composed of Amphiphilic Block Copolymers and Amphiphilic Heterografted Polymer Brushes Determined by Small-Angle X-ray Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Szymusiak, Magdalena [Department; Kalkowski, Joseph [Department; Luo, Hanying [Department; Donovan, Alexander J. [Department; Zhang, Pin [Department; Liu, Chang [Department; Shang, Weifeng [Department; Irving, Thomas [Department; Herrera-Alonso, Margarita [Department; Liu, Ying [Department; Department

    2017-08-16

    A large group of functional nanomaterials employed in biomedical applications, including targeted drug delivery, relies on amphiphilic polymers to encapsulate therapeutic payloads via self-assembly processes. Knowledge of the micelle structures will provide critical insights into design of polymeric drug delivery systems. Core–shell micelles composed of linear diblock copolymers poly(ethylene glycol)-b-poly(caprolactone) (PEG-b-PCL), poly(ethylene oxide)-b-poly(lactic acid) (PEG-b-PLA), as well as a heterografted brush consisting of a poly(glycidyl methacrylate) backbone with PEG and PLA branches (PGMA-g-PEG/PLA) were characterized by dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS) measurements to gain structural information regarding the particle morphology, core–shell size, and aggregation number. The structural information at this quasi-equilibrium state can also be used as a reference when studying the kinetics of polymer micellization.

  6. 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.)

  7. Optical fiber-based core-shell coaxially structured hybrid cells for self-powered nanosystems

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Caofeng; Zhu, Guang [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia (United States); Guo, Wenxi [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia (United States); State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Dong, Lin [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia (United States); School of Materials Science and Enginnering, Zhenzhou University, Zhenghou 450001 (China); Wang, Zhong Lin [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia (United States); Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing (China)

    2012-07-03

    An optical fiber-based 3D hybrid cell consisting of a coaxially structured dye-sensitized solar cell (DSSC) and a nanogenerator (NG) for simultaneously or independently harvesting solar and mechanical energy is demonstrated. The current output of the hybrid cell is dominated by the DSSC, and the voltage output is dominated by the NG; these can be utilized complementarily for different applications. The output of the hybrid cell is about 7.65 {mu}A current and 3.3 V voltage, which is strong enough to power nanodevices and even commercial electronic components. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. Analysis of thin-walled cylindrical composite shell structures subject to axial and bending loads: Concept development, analytical modeling and experimental verification

    Science.gov (United States)

    Mahadev, Sthanu

    Continued research and development efforts devoted in recent years have generated novel avenues towards the advancement of efficient and effective, slender laminated fiber-reinforced composite members. Numerous studies have focused on the modeling and response characterization of composite structures with particular relevance to thin-walled cylindrical composite shells. This class of shell configurations is being actively explored to fully determine their mechanical efficacy as primary aerospace structural members. The proposed research is targeted towards formulating a composite shell theory based prognosis methodology that entails an elaborate analysis and investigation of thin-walled cylindrical shell type laminated composite configurations that are highly desirable in increasing number of mechanical and aerospace applications. The prime motivation to adopt this theory arises from its superior ability to generate simple yet viable closed-form analytical solution procedure to numerous geometrically intense, inherent curvature possessing composite structures. This analytical evaluative routine offers to acquire a first-hand insight on the primary mechanical characteristics that essentially govern the behavior of slender composite shells under typical static loading conditions. Current work exposes the robustness of this mathematical framework via demonstrating its potential towards the prediction of structural properties such as axial stiffness and bending stiffness respectively. Longitudinal ply-stress computations are investigated upon deriving the global stiffness matrix model for composite cylindrical tubes with circular cross-sections. Additionally, this work employs a finite element based numerical technique to substantiate the analytical results reported for cylindrically shaped circular composite tubes. Furthermore, this concept development is extended to the study of thin-walled, open cross-sectioned, curved laminated shells that are geometrically

  9. Eduardo Torroja y la International Association for Shell and Spatial Structures (IASS

    Directory of Open Access Journals (Sweden)

    Astudillo, R.

    2014-12-01

    Full Text Available Eduardo Torroja’s legacy doesn’t limit to his innovative designs, or to his contributions to concrete structures and their codes development. Throw his life, he founded, or contributed to found, several associations, national and international, which as IASS (1959 are working nowadays leading the progress of civil and architectural construction.El legado de Eduardo Torroja no se limita a sus innovadores proyectos, o a sus aportaciones al cálculo y desarrollo del hormigón armado y pretensado. A lo largo de su vida, fundó, o contribuyó a fundar, diversas asociaciones, nacionales e internacionales que, como la IASS (1959, continúan vivas liderando el progreso de la construcción civil y arquitectónica.

  10. Probing nuclear shell structure beyond the N=40 subshell using multiple Coulomb excitation and transfer experiments

    Energy Technology Data Exchange (ETDEWEB)

    Hellgartner, Stefanie Christine

    2015-11-13

    In this work, the N=40 subshell closure is investigated with two complementary methods using a radioactive {sup 72}Zn ISOLDE beam: One- and two-neutron transfer reactions and multiple Coulomb excitation. In the one-neutron transfer reaction, two new levels of {sup 73}Zn were discovered. The two-neutron transfer channel allowed to study the differential cross section of the ground state and the 2{sup +}{sub 1} state of {sup 74}Zn. In the Coulomb excitation experiment, the measured B(E2) values and quadrupole moments of {sup 72}Zn showed that the yrast states 0{sup +}{sub 1}, 2{sup +}{sub 1} and 4{sup +}{sub 1} are moderately collective. Contrary, the 0{sup +}{sub 2} state has a different structure, since it features a stronger closed N=40 configuration compared to the ground state.

  11. Enhancing photocatalytic activity by using TiO2-MgO core-shell-structured nanoparticles

    International Nuclear Information System (INIS)

    Jung, Hyun Suk; Lee, Jung-Kun; Nastasi, Michael; Kim, Jeong-Ryeol; Lee, Sang-Wook; Kim, Jin Young; Park, Jong-Sung; Hong, Kug Sun; Shin, Hyunho

    2006-01-01

    Hygroscopic Mg(OH) 2 gel was topotactically decomposed on TiO 2 particle surfaces, resulting in highly nanoporous MgO-coated TiO 2 particles. The highly hygroscopic and nanoporous MgO shell absorbed more water molecules and hydroxyl groups from the environment to yield an improved photocatalytic property of the core-shell particles as compared to the uncoated TiO 2 counterpart

  12. 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.

  13. 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.

  14. The Shell Structure Effect on the Vapor Selectivity of Monolayer-Protected Gold Nanoparticle Sensors

    Directory of Open Access Journals (Sweden)

    Rui-Xuan Huang

    2014-02-01

    Full Text Available Four types of monolayer-protected gold nanoclusters (MPCs were synthesized and characterized as active layers of vapor sensors. An interdigitated microelectrode (IDE and quartz crystal microbalance (QCM were used to measure the electrical resistance and mass loading changes of MPC films during vapor sorption. The vapor sensing selectivity was influenced by the ligand structure of the monolayer on the surface of gold nanoparticles. The responses of MPC-coated QCM were mainly determined according to the affinity between the vapors and surface ligands of MPCs. The responses to the resistance changes of the MPC films were due to the effectiveness of the swelling when vapor was absorbed. It was observed that resistive sensitivity to polar organics could be greatly enhanced when the MPC contained ligands that contain interior polar functional groups with exterior nonpolar groups. This finding reveals that reducing interparticle attraction by using non-polar exterior groups could increase effective swelling and therefore enhance the sensitivity of MPC-coated chemiresistors.

  15. Effective enhancement of gas separation performance in mixed matrix membranes using core/shell structured multi-walled carbon nanotube/graphene oxide nanoribbons

    Science.gov (United States)

    Xue, Qingzhong; Pan, Xinglong; Li, Xiaofang; Zhang, Jianqiang; Guo, Qikai

    2017-02-01

    Novel core/shell structured multi-walled carbon nanotube/graphene oxide nanoribbons (MWCNT@GONRs) nanohybrids were successfully prepared using a modified chemical longitudinal unzipping method. Subsequently, the MWCNT@GONRs nanohybrids were used as fillers to enhance the gas separation performance of polyimide based mixed matrix membranes (MMMs). It is found that MMMs concurrently exhibited higher gas selectivity and higher gas permeability compared to pristine polyimide. The high gas selectivity could be attributed to the GONRs shell, which provided a selective barrier and large gas adsorbed area, while the high gas permeability resulted from the hollow structured MWCNTs core with smooth internal surface, which acted as a rapid transport channel. MWCNT@GONRs could be promising candidates to improve gas separation performance of MMMs due to the unique microstructures, ease of synthesis and low filling loading.

  16. 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.

  17. 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.

  18. Palladium nanoparticles encapsulated in core-shell silica: A structured hydrogenation catalyst with enhanced activity for reduction of oxyanion water pollutants

    KAUST Repository

    Wang, Yin; Liu, Jinyong; Wang, Peng; Werth, Charles; Strathmann, Timothy J.

    2014-01-01

    Noble metal nanoparticles have been applied to mediate catalytic removal of toxic oxyanions and halogenated hydrocarbons in contaminated water using H2 as a clean and sustainable reductant. However, activity loss by nanoparticle aggregation and difficulty of nanoparticle recovery are two major challenges to widespread technology adoption. Herein, we report the synthesis of a core-shell-structured catalyst with encapsulated Pd nanoparticles and its enhanced catalytic activity in reduction of bromate (BrO3-), a regulated carcinogenic oxyanion produced during drinking water disinfection process, using 1 atm H2 at room temperature. The catalyst material consists of a nonporous silica core decorated with preformed octahedral Pd nanoparticles that were further encapsulated within an ordered mesoporous silica shell (i.e., SiO2@Pd@mSiO2). Well-defined mesopores (2.3 nm) provide a physical barrier to prevent Pd nanoparticle (6 nm) movement, aggregation, and detachment from the support into water. Compared to freely suspended Pd nanoparticles and SiO2@Pd, encapsulation in the mesoporous silica shell significantly enhanced Pd catalytic activity (by a factor of 10) under circumneutral pH conditions that are most relevant to water purification applications. Mechanistic investigation of material surface properties combined with Langmuir-Hinshelwood modeling of kinetic data suggest that mesoporous silica shell enhances activity by promoting BrO3- adsorption near the Pd active sites. The dual function of the mesoporous shell, enhancing Pd catalyst activity and preventing aggregation of active nanoparticles, suggests a promising general strategy of using metal nanoparticle catalysts for water purification and related aqueous-phase applications.

  19. Palladium nanoparticles encapsulated in core-shell silica: A structured hydrogenation catalyst with enhanced activity for reduction of oxyanion water pollutants

    KAUST Repository

    Wang, Yin

    2014-10-03

    Noble metal nanoparticles have been applied to mediate catalytic removal of toxic oxyanions and halogenated hydrocarbons in contaminated water using H2 as a clean and sustainable reductant. However, activity loss by nanoparticle aggregation and difficulty of nanoparticle recovery are two major challenges to widespread technology adoption. Herein, we report the synthesis of a core-shell-structured catalyst with encapsulated Pd nanoparticles and its enhanced catalytic activity in reduction of bromate (BrO3-), a regulated carcinogenic oxyanion produced during drinking water disinfection process, using 1 atm H2 at room temperature. The catalyst material consists of a nonporous silica core decorated with preformed octahedral Pd nanoparticles that were further encapsulated within an ordered mesoporous silica shell (i.e., SiO2@Pd@mSiO2). Well-defined mesopores (2.3 nm) provide a physical barrier to prevent Pd nanoparticle (6 nm) movement, aggregation, and detachment from the support into water. Compared to freely suspended Pd nanoparticles and SiO2@Pd, encapsulation in the mesoporous silica shell significantly enhanced Pd catalytic activity (by a factor of 10) under circumneutral pH conditions that are most relevant to water purification applications. Mechanistic investigation of material surface properties combined with Langmuir-Hinshelwood modeling of kinetic data suggest that mesoporous silica shell enhances activity by promoting BrO3- adsorption near the Pd active sites. The dual function of the mesoporous shell, enhancing Pd catalyst activity and preventing aggregation of active nanoparticles, suggests a promising general strategy of using metal nanoparticle catalysts for water purification and related aqueous-phase applications.

  20. Electrochemical Impedance Spectroscopy Illuminating Performance Evolution of Porous Core–Shell Structured Nickel/Nickel Oxide Anode Materials

    International Nuclear Information System (INIS)

    Yan, Bo; Li, Minsi; Li, Xifei; Bai, Zhimin; Dong, Lei; Li, Dejun

    2015-01-01

    Highlights: • The electrochemical reaction kinetics of the Ni/NiO anode was studied for the first time. • Charge transfer resistance is main contribution to total resistance during discharge process. • The slow growth of the SEI film is responsible for the capacity fading upon cycling. • Some promising strategies to optimize NiO anode performance were summarized. - Abstract: The electrochemical reaction kinetics of the porous core–shell structured Ni/NiO anode for Li ion battery application is systematically investigated by monitoring the electrochemical impedance evolution for the first time. The electrochemical impedance under prescribed condition is measured by using impedance spectroscopy in equilibrium conditions at various depths of discharge (DOD) during charge–discharge cycles. The Nyquist plots of the binder-free porous Ni/NiO electrode are interpreted with a selective equivalent circuit composed of solution resistance, solid electrolyte interphase (SEI) film, charge transfer and solid state diffusion. The impedance analysis shows that the change of charge transfer resistance is the main contribution to the total resistance change during discharge, and the surface configuration of the obtained electrode may experience significant change during the first two cycles. Meanwhile, the increase of internal resistance reduced the utilization efficiency of the active material may be another convincing factor to increase the irreversible capacity. In addition, the impedance evolution of the as-prepared electrode during charge–discharge cycles reveals that the slow growth of the SEI film is responsible for the capacity fading after long term cycling. As a result, several strategies are summarized to optimize the electrochemical performances of transition metal oxide anodes for lithium ion batteries

  1. 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}.

  2. Application of core–shell-structured CdTe-SiO2 quantum dots synthesized via a facile solution method for improving latent fingerprint detection

    International Nuclear Information System (INIS)

    Gao Feng; Han Jiaxing; Lv Caifeng; Wang Qin; Zhang Jun; Li Qun; Bao Liru; Li Xin

    2012-01-01

    Fingerprint detection is important in criminal investigation. This paper reports a facile powder brushing technique for improving latent fingerprint detection using core–shell-structured CdTe-SiO 2 quantum dots (QDs) as fluorescent labeling marks. Core–shell-structured CdTe-SiO 2 QDs are prepared via a simple solution-based approach using NH 2 NH 2 ·H 2 O as pH adjustor and stabilizer, and their application for improving latent fingerprint detection is explored. The obtained CdTe-SiO 2 QDs show spherical shapes with well-defined core–shell structures encapsulating different amounts of QDs depending on the type of the pH adjustor and stabilizer. Moreover, the fluorescence of CdTe-SiO 2 QDs is largely enhanced by surface modification of the SiO 2 shell. The CdTe-SiO 2 QDs overcome the oxidation problem of pure CdTe QDs in air, thus affording better variability with strong adhesive ability, better resolution, and bright emission colors for practical application in latent fingerprint detection. In comparison with the conventional fluorescence powders, silver powders, and others, the effectiveness of CdTe-SiO 2 QD powders for detection of latent fingerprints present on a large variety of object surfaces is greatly improved. The synthesis method for CdTe-SiO 2 QDs is simple, cheap, and easy for large-scale production, and thus offers many advantages in the practical application of fingerprint detection.

  3. 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)

  4. High performance and durability of order-structured cathode catalyst layer based on TiO_2@PANI core-shell nanowire arrays

    International Nuclear Information System (INIS)

    Chen, Ming; Wang, Meng; Yang, Zhaoyi; Wang, Xindong

    2017-01-01

    Highlights: • TiO_2@PANI core-shell nanowire arrays were prepared and applied as catalyst support. • As-prepared Pt-TiO_2@PANI core-shell nanowire arrays were applied as order-structured cathode catalyst layer. • The novel cathode catalyst structure without Nafion"® ionomer enhance the performance and durability of PEMFC. - Abstract: In this paper, an order-structured cathode catalyst layer consisting of Pt-TiO_2@PANI core-shell nanowire arrays that in situ grown on commercial gas diffusion layer (GDL) are prepared and applied to membrane electrode assembly (MEA) of proton exchange membrane fuel cell (PEMFC). In order to prepare the TiO_2@PANI core-shell nanowire arrays with suitable porosity and prominent conductivity, the morphologies of the TiO_2 nanoarray and electrochemical polymerization process of aniline are schematically investigated. The MEA with order-structured cathode catalyst layer is assembled in the single cell to evaluate the electrochemical performance and durability of PEMFC. As a result, the PEMFC with order-structured cathode catalyst layer shows higher peak power density (773.54 mW cm"−"2) than conventional PEMFC (699.30 mW cm"−"2). Electrochemically active surface area (ECSA) and charge transfer impedance (R_c_t) are measured before and after accelerated degradation test (ADT), and the corresponding experimental results indicate the novel cathode structure exhibits a better stability with respect to conventional cathode. The enhanced electrochemical performance and durability toward PEMFC can be ascribed to the order-structured cathode nanoarray structure with high specific surface area increases the utilization of catalyst and reduces the tortuosity of transport pathways, and the synergistic effect between TiO_2@PANI support and Pt nanoparticles promotes the high efficiency of electrochemical reaction and improves the stability of catalyst. This research provides a facile and controllable method to prepare order-structured

  5. High performance and durability of order-structured cathode catalyst layer based on TiO{sub 2}@PANI core-shell nanowire arrays

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Ming; Wang, Meng; Yang, Zhaoyi [State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, 30 College Road, Beijing 100083 (China); School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, 30 College Road, Beijing 100083 (China); Wang, Xindong, E-mail: echem@ustb.edu.cn [State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, 30 College Road, Beijing 100083 (China); School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, 30 College Road, Beijing 100083 (China)

    2017-06-01

    Highlights: • TiO{sub 2}@PANI core-shell nanowire arrays were prepared and applied as catalyst support. • As-prepared Pt-TiO{sub 2}@PANI core-shell nanowire arrays were applied as order-structured cathode catalyst layer. • The novel cathode catalyst structure without Nafion{sup ®} ionomer enhance the performance and durability of PEMFC. - Abstract: In this paper, an order-structured cathode catalyst layer consisting of Pt-TiO{sub 2}@PANI core-shell nanowire arrays that in situ grown on commercial gas diffusion layer (GDL) are prepared and applied to membrane electrode assembly (MEA) of proton exchange membrane fuel cell (PEMFC). In order to prepare the TiO{sub 2}@PANI core-shell nanowire arrays with suitable porosity and prominent conductivity, the morphologies of the TiO{sub 2} nanoarray and electrochemical polymerization process of aniline are schematically investigated. The MEA with order-structured cathode catalyst layer is assembled in the single cell to evaluate the electrochemical performance and durability of PEMFC. As a result, the PEMFC with order-structured cathode catalyst layer shows higher peak power density (773.54 mW cm{sup −2}) than conventional PEMFC (699.30 mW cm{sup −2}). Electrochemically active surface area (ECSA) and charge transfer impedance (R{sub ct}) are measured before and after accelerated degradation test (ADT), and the corresponding experimental results indicate the novel cathode structure exhibits a better stability with respect to conventional cathode. The enhanced electrochemical performance and durability toward PEMFC can be ascribed to the order-structured cathode nanoarray structure with high specific surface area increases the utilization of catalyst and reduces the tortuosity of transport pathways, and the synergistic effect between TiO{sub 2}@PANI support and Pt nanoparticles promotes the high efficiency of electrochemical reaction and improves the stability of catalyst. This research provides a facile and

  6. 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

  7. 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.

  8. The fabrication of highly uniform ZnO/CdS core/shell structures using a spin-coating-based successive ion layer adsorption and reaction method

    International Nuclear Information System (INIS)

    Joo, Jinmyoung; Kim, Darae; Yun, Dong-Jin; Jun, Hwichan; Rhee, Shi-Woo; Lee, Jae Sung; Yong, Kijung; Jeon, Sangmin; Kim, Sungjee

    2010-01-01

    We developed a successive ion layer adsorption and reaction method based on spin-coating (spin-SILAR) and applied the method to the fabrication of highly uniform ZnO/CdS core/shell nanowire arrays. Because the adsorption, reaction, and rinsing steps occur simultaneously during spin-coating, the spin-SILAR method does not require rinsing steps between the alternating ion adsorption steps, making the growth process simpler and faster than conventional SILAR methods based on dip-coating (dip-SILAR). The ZnO/CdS core/shell nanowire arrays prepared by spin-SILAR had a denser and more uniform structure than those prepared by dip-SILAR, resulting in the higher power efficiency for use in photoelectrochemical cells.

  9. The fabrication of highly uniform ZnO/CdS core/shell structures using a spin-coating-based successive ion layer adsorption and reaction method

    Energy Technology Data Exchange (ETDEWEB)

    Joo, Jinmyoung; Kim, Darae; Yun, Dong-Jin; Jun, Hwichan; Rhee, Shi-Woo; Lee, Jae Sung; Yong, Kijung; Jeon, Sangmin [System on Chip Chemical Process Research, Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang (Korea, Republic of); Kim, Sungjee, E-mail: jeons@postech.ac.kr [Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang (Korea, Republic of)

    2010-08-13

    We developed a successive ion layer adsorption and reaction method based on spin-coating (spin-SILAR) and applied the method to the fabrication of highly uniform ZnO/CdS core/shell nanowire arrays. Because the adsorption, reaction, and rinsing steps occur simultaneously during spin-coating, the spin-SILAR method does not require rinsing steps between the alternating ion adsorption steps, making the growth process simpler and faster than conventional SILAR methods based on dip-coating (dip-SILAR). The ZnO/CdS core/shell nanowire arrays prepared by spin-SILAR had a denser and more uniform structure than those prepared by dip-SILAR, resulting in the higher power efficiency for use in photoelectrochemical cells.

  10. Modeling of a fluid-loaded smart shell structure for active noise and vibration control using a coupled finite element–boundary element approach

    International Nuclear Information System (INIS)

    Ringwelski, S; Gabbert, U

    2010-01-01

    A recently developed approach for the simulation and design of a fluid-loaded lightweight structure with surface-mounted piezoelectric actuators and sensors capable of actively reducing the sound radiation and the vibration is presented. The objective of this paper is to describe the theoretical background of the approach in which the FEM is applied to model the actively controlled shell structure. The FEM is also employed to model finite fluid domains around the shell structure as well as fluid domains that are partially or totally bounded by the structure. Boundary elements are used to characterize the unbounded acoustic pressure fields. The approach presented is based on the coupling of piezoelectric and acoustic finite elements with boundary elements. A coupled finite element–boundary element model is derived by introducing coupling conditions at the fluid–fluid and fluid–structure interfaces. Because of the possibility of using piezoelectric patches as actuators and sensors, feedback control algorithms can be implemented directly into the multi-coupled structural–acoustic approach to provide a closed-loop model for the design of active noise and vibration control. In order to demonstrate the applicability of the approach developed, a number of test simulations are carried out and the results are compared with experimental data. As a test case, a box-shaped shell structure with surface-mounted piezoelectric actuators and four sensors and an open rearward end is considered. A comparison between the measured values and those predicted by the coupled finite element–boundary element model shows a good agreement

  11. Impacts from Partial Removal of Decommissioned Oil and Gas Platforms on Fish Biomass and Production on the Remaining Platform Structure and Surrounding Shell Mounds.

    Science.gov (United States)

    Claisse, Jeremy T; Pondella, Daniel J; Love, Milton; Zahn, Laurel A; Williams, Chelsea M; Bull, Ann S

    2015-01-01

    When oil and gas platforms become obsolete they go through a decommissioning process. This may include partial removal (from the surface to 26 m depth) or complete removal of the platform structure. While complete removal would likely eliminate most of the existing fish biomass and associated secondary production, we find that the potential impacts of partial removal would likely be limited on all but one platform off the coast of California. On average 80% of fish biomass and 86% of secondary fish production would be retained after partial removal, with above 90% retention expected for both metrics on many platforms. Partial removal would likely result in the loss of fish biomass and production for species typically found residing in the shallow portions of the platform structure. However, these fishes generally represent a small proportion of the fishes associated with these platforms. More characteristic of platform fauna are the primarily deeper-dwelling rockfishes (genus Sebastes). "Shell mounds" are biogenic reefs that surround some of these platforms resulting from an accumulation of mollusk shells that have fallen from the shallow areas of the platforms mostly above the depth of partial removal. We found that shell mounds are moderately productive fish habitats, similar to or greater than natural rocky reefs in the region at comparable depths. The complexity and areal extent of these biogenic habitats, and the associated fish biomass and production, will likely be reduced after either partial or complete platform removal. Habitat augmentation by placing the partially removed platform superstructure or some other additional habitat enrichment material (e.g., rock boulders) on the seafloor adjacent to the base of partially removed platforms provides additional options to enhance fish production, potentially mitigating reductions in shell mound habitat.

  12. Impacts from Partial Removal of Decommissioned Oil and Gas Platforms on Fish Biomass and Production on the Remaining Platform Structure and Surrounding Shell Mounds.

    Directory of Open Access Journals (Sweden)

    Jeremy T Claisse

    Full Text Available When oil and gas platforms become obsolete they go through a decommissioning process. This may include partial removal (from the surface to 26 m depth or complete removal of the platform structure. While complete removal would likely eliminate most of the existing fish biomass and associated secondary production, we find that the potential impacts of partial removal would likely be limited on all but one platform off the coast of California. On average 80% of fish biomass and 86% of secondary fish production would be retained after partial removal, with above 90% retention expected for both metrics on many platforms. Partial removal would likely result in the loss of fish biomass and production for species typically found residing in the shallow portions of the platform structure. However, these fishes generally represent a small proportion of the fishes associated with these platforms. More characteristic of platform fauna are the primarily deeper-dwelling rockfishes (genus Sebastes. "Shell mounds" are biogenic reefs that surround some of these platforms resulting from an accumulation of mollusk shells that have fallen from the shallow areas of the platforms mostly above the depth of partial removal. We found that shell mounds are moderately productive fish habitats, similar to or greater than natural rocky reefs in the region at comparable depths. The complexity and areal extent of these biogenic habitats, and the associated fish biomass and production, will likely be reduced after either partial or complete platform removal. Habitat augmentation by placing the partially removed platform superstructure or some other additional habitat enrichment material (e.g., rock boulders on the seafloor adjacent to the base of partially removed platforms provides additional options to enhance fish production, potentially mitigating reductions in shell mound habitat.

  13. Estimation Of Young’s Modulus Of Elesticity By The Form Finding Of Grid Shell Structures By The Dynamic Relaxation Method

    Directory of Open Access Journals (Sweden)

    Grančičová Ivana

    2015-12-01

    Full Text Available The paper is basically focused on the process of form finding by the dynamic relaxation method (DRM with the aid of computational tools that enable us to make many calculations with different inputs. There are many important input values with a significant impact on the course of the calculations and the resulting displacement of a structure. One of these values is Young’s modulus of elasticity. This value has a considerable impact on the final displacement of a grid shell structure and the resulting internal forces.

  14. Beta decay and structure of exotic nuclei in the mass regions N=Z, A {approx} 70 and near the N=20 closed shell

    Energy Technology Data Exchange (ETDEWEB)

    Courtin, S.; Baumann, P.; Dessagne, Ph.; Marechal, F.; Miehe, Ch.; Perrot, F.; Poirier, E.; Ramdhane, M. [Institut de Recherches Subatomiques, Strasbourg Cedex 2 (France); ISOLDE collaboration

    2004-09-15

    This paper describes two beta decay experiments performed at the CERN/ISOLDE mass separator. The structure of {sup 74}Kr has been studied using a total absorption {gamma} spectrometer (TAgS). The measured Gamow-Teller strength is presented and compared to HFBCS+QRPA calculations. The {sup 33}Na decay is also presented. The structure of the {sup 33}Mg daughter nucleus is compared to shell-model calculations, showing for the first time an inversion of states in the A{sub {approx}}35 mass region. (author)

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. Studies on connecting structure between steel shell and steel reinforced concrete; Kokaku to tekkotsu tekkin concrete tono ketsugo kozo ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Morimoto, A. [Kinki University, Osaka (Japan). Faculty of Science and Engineering; Morikawa, H.; Ito, N. [Metropolitan Expressway Public Corp., Tokyo (Japan)

    1996-02-15

    On the insert reinforcing bar structure for the connecting part of the main tower of cable stayed bridges, this paper reports verification results on a load resistant safety with a full-scale model, structure analysis and construction work. The basic structure was composed of a drilled steel shell, inserted reinforcing bars, fixing structure of bars in lining concrete of the shell and a pressure bearing plate. As an experimental result, the connecting part had a sufficient load carrying capacity against both tensile and compressive loads. The shear stress of the insert reinforcing bar structure was estimated successfully under von Mises`s condition. The shear spring constant in deformation characteristics was linearly proportional to an inserted reinforcing bar ratio. In earthquake, nearly 60% of an allowable compressive load was transferred to concrete through the pressure bearing plate. The analytical results of load resistant deformation characteristics of the connecting part well agreed with experimental ones, and the proposed analytical model was applicable to estimation of a dynamic behavior. 5 refs., 22 figs., 4 tabs.

  20. Structural and magnetic properties of CoFe{sub 2}O{sub 4}/NiFe{sub 2}O{sub 4} core/shell nanocomposite prepared by the hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Sattar, A.A. [Department of Physics, Faculty of Science, Ain Shams University, 11566 Abbasia, Cairo (Egypt); EL-Sayed, H.M., E-mail: h_m_elsaid@hotmail.com [Department of Physics, Faculty of Science, Ain Shams University, 11566 Abbasia, Cairo (Egypt); ALsuqia, Ibrahim [Department of Physics, Faculty of Education and Applied Science, Hajjah University, Alshahli, Hajjah (Yemen)

    2015-12-01

    CoFe{sub 2}O{sub 4}/NiFe{sub 2}O{sub 4} core/shell magnetic nanocomposite was synthesized by using hydrothermal method.The analysis of XRD indicated the coexistence of CoFe{sub 2}O{sub 4}, NiFe{sub 2}O{sub 4}as core/shell composite. The core/shell structure of the composite sample has been confirmed by HR-TEM images, EDX and FT-IR measurements. The size of obtained core/shell nanoparticles was 17 nm in core diameter and about 3 nm in shell thickness. The magnetization measurements showed that both the coercive field and the saturation magnetization of the resulting core/shell nanocomposite were slightly decreased compared to those of the CoFe{sub 2}O{sub 4} core but the thermal stability is of the magnetization parameter was enhanced. Furthermore, superparamagnetic phase is established at temperatures higher than the room temperature. The results were discussed in terms of the surface pinning and the magnetic interaction at the interface between the core and shell. - Highlights: • CoFe{sub 2}O{sub 4}/NiFe{sub 2}O{sub 4} core/shell could be prepared by hydrothermal method. • The structural analysis proved the formation of NiFe{sub 2}O{sub 4} shell with thickness 3 nm. • The thermal stability of M{sub s} and H{sub c} is enhanced due to the presence of NiFe{sub 2}O{sub 4} as a shell. • Super paramagnetic transition is confirmed and the effective magnetic anisotropy was calculated.

  1. Hi shells, supershells, shell-like objects, and ''worms''

    International Nuclear Information System (INIS)

    Heiles, C.

    1984-01-01

    We present photographic representations of the combination of two Hi surveys, so as to eliminate the survey boundaries at Vertical BarbVertical Bar = 10 0 . We also present high-contrast photographs for particular velocities to exhibit weak Hi features. All of these photographs were used to prepare a new list of Hi shells, supershells, and shell-like objects. We discuss the structure of three shell-like objects that are associated with high-velocity gas, and with gas at all velocities that is associated with radio continuum loops I, II, and III. We use spatial filtering to find wiggly gas filaments: ''worms'': crawling away from the galactic plane in the inner Galaxy. The ''worms'' are probably parts of shells that are open at the top; such shells should be good sources of hot gas for the galactic halo

  2. Static and free-vibration analyses of cracks in thin-shell structures based on an isogeometric-meshfree coupling approach

    Science.gov (United States)

    Nguyen-Thanh, Nhon; Li, Weidong; Zhou, Kun

    2018-03-01

    This paper develops a coupling approach which integrates the meshfree method and isogeometric analysis (IGA) for static and free-vibration analyses of cracks in thin-shell structures. In this approach, the domain surrounding the cracks is represented by the meshfree method while the rest domain is meshed by IGA. The present approach is capable of preserving geometry exactness and high continuity of IGA. The local refinement is achieved by adding the nodes along the background cells in the meshfree domain. Moreover, the equivalent domain integral technique for three-dimensional problems is derived from the additional Kirchhoff-Love theory to compute the J-integral for the thin-shell model. The proposed approach is able to address the problems involving through-the-thickness cracks without using additional rotational degrees of freedom, which facilitates the enrichment strategy for crack tips. The crack tip enrichment effects and the stress distribution and displacements around the crack tips are investigated. Free vibrations of cracks in thin shells are also analyzed. Numerical examples are presented to demonstrate the accuracy and computational efficiency of the coupling approach.

  3. 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.

  4. 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.

  5. 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.

  6. Study of neutron-rich nuclei structure around the N=28 shell closure using the in-beam gamma spectroscopy technique

    International Nuclear Information System (INIS)

    Bastin, B.

    2007-10-01

    For a few years now, a loss of magicity in neutron-rich nuclei near the neutron drip-line at N=28 has been suggested and observed. Deformation in these nuclei has been observed. The deformation was explained in S isotopes as being due to a moderate reduction of the N=28 shell closure together with a proton induced collectivity originating from the near degeneracy of the proton d3/2 and s1/2 orbitals. As a consequence, the observed deformation seems to result from a subtle interplay between neutron and proton excitations. Since the proton configuration in the Si isotopes is expected to be more stable due to the Z=14 sub-shell gap, 42 Si was considered as a key nucleus in order to distinguish the different effects responsible for the structural changes observed at N=28. Even if it is at the limits of our technical possibilities, an in-beam gamma-spectroscopy experiment using two-step fragmentation and one or several nucleons knockout reaction mechanisms was performed at GANIL. The measurement of the energy of the first excited state in 42 Si, combined with the observation of 38,40 Si and the spectroscopy of 41,43 P, has given evidence for the loss of magicity at N=28 far from stability. Modifications of the effective interaction used in modern shell model calculations have been completed following this investigation, increasing its predictive character. This study confirms the role of the tensor force and the density dependence of the spin-orbit interaction in the collapse of the N=28 shell closure. (author)

  7. 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

  8. A novel durable double-conductive core-shell structure applying to the synthesis of silicon anode for lithium ion batteries

    Science.gov (United States)

    Xing, Yan; Shen, Tong; Guo, Ting; Wang, Xiuli; Xia, Xinhui; Gu, Changdong; Tu, Jiangping

    2018-04-01

    Si/C composites are currently the most commercially viable next-generation lithium-ion battery anode materials due to their high specific capacity. However, there are still many obstacles need to be overcome such as short cycle life and poor conductivity. In this work, we design and successfully synthesis an excellent durable double-conductive core-shell structure p-Si-Ag/C composites. Interestingly, this well-designed structure offers remarkable conductivity (both internal and external) due to the introduction of silver particles and carbon layer. The carbon layer acts as a protective layer to maintain the integrity of the structure as well as avoids the direct contact of silicon with electrolyte. As a result, the durable double-conductive core-shell structure p-Si-Ag/C composites exhibit outstanding cycling stability of roughly 1000 mAh g-1 after 200 cycles at a current density of 0.2 A g-1 and retain 765 mAh g-1 even at a high current density of 2 A g-1, indicating a great improvement in electrochemical performance compared with traditional silicon electrode. Our research results provide a novel pathway for production of high-performance Si-based anodes to extending the cycle life and specific capacity of commercial lithium ion batteries.

  9. The CEASEMT system (Computer analysis of the thermomechanical structure behavior). The TRICO code, for analysis of three-dimensional structures comprising shells and beams - Statics - Dynamics - Elasticity - Plasticity - Buckling - Large displacements

    International Nuclear Information System (INIS)

    1977-01-01

    The TRICO part of the CEA-SEMT system is concerned with the elasticity or plasticity computation of structures made of thin shells and beams. TRICO uses the finite element method for shells and beams. TRICO also allows the dynamic computing of structures: search for eigenmodes and eigenfrequencies or response to any sinusoidal excitation, response to time dependent loads (direct integration) in elasticity or plasticity. The mechanical structures can offer any shape and be composed of a number of materials. A special effort has been put on data input (read without any format), the data being arranged in optional commands with a precise physical sense corresponding to an order for the program. A dynamic control of the memory allows the size of the program to be adapted to that the problem to be processed. Results are printed on listing, or many be described on a magnetic tape [fr

  10. Inorganic/organic nanocomposites: Reaching a high filler content without increasing viscosity using core-shell structured nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Benhadjala, W., E-mail: warda.benhadjala@cea.fr [IMS Laboratory - UMR CNRS 5218, University of Bordeaux, 351 Cours de la Libération, 33405 Talence (France); CEA, LETI, Minatec Campus, 38000 Grenoble (France); Gravoueille, M.; Weiss, M. [EDF, Centre d' Expertise et d' Inspection dans les Domaines de la Réalisation et de l' Exploitation (CEIDRE), Chinon, BP 80, 37420 Avoine (France); Bord-Majek, I.; Béchou, L.; Ousten, Y. [IMS Laboratory - UMR CNRS 5218, University of Bordeaux, 351 Cours de la Libération, 33405 Talence (France); Suhir, E. [Maseeh College of Engineering and Computer Science, Portland State University, Oregon 97201 (United States); Buet, M.; Louarn, M.; Rougé, F.; Gaud, V. [Polyrise SAS, 16 Avenue Pey Berland, 33607 Pessac (France)

    2015-11-23

    Extensive research is being conducted on the development of inorganic/organic nanocomposites for a wide variety of applications in microelectronics, biotechnologies, photonics, adhesives, or optical coatings. High filler contents are usually required to fully optimize the nanocomposites properties. However, numerous studies demonstrated that traditional composite viscosity increases with increasing the filler concentration reducing therefore significantly the material processability. In this work, we synthesized inorganic/organic core-shell nanocomposites with different shell thicknesses. By reducing the shell thickness while maintaining a constant core size, the nanoparticle molecular mass decreases but the nanocomposite filler fraction is correlatively increased. We performed viscosity measurements, which clearly highlighted that intrinsic viscosity of hybrid nanoparticles decreases as the molecular mass decreases, and thus, as the filler fraction increases, as opposed to Einstein predictions about the viscosity of traditional inorganic/polymer two-phase mixtures. This exceptional behavior, modeled by Mark-Houwink-Sakurada equation, proves to be a significant breakthrough for the development of industrializable nanocomposites with high filler contents.

  11. The Structure of the Heavy Calcium Isotopes and the Effective Interaction in the sd-fp Shell

    CERN Multimedia

    Dorvaux, O; Nowacki, F; Courtin, S; Marechal, F; Siiskonen, T M; Perrot, F; Pietri, S B

    2002-01-01

    Nuclei with 40 $<$ A $<$ 56, near the stability line, are very well described in the frame of the shell model. However, when the number of neutrons increases, the situation becomes more complex which explains why the interaction can be found very dissimilar within different calculations. Heavy Ca isotopes, because of the simplicity of their wave-functions, correspond to the optimal choice to fix unambiguously the interaction in this mass region.\\\\ It is proposed to measure the $\\beta$-decay of $^{51, 52, 53}$K with the help of an utmost performing neutron (TONNERRE array) and $\\gamma$- (Miniball clusters) detection, allowing efficient coincidence measurements. This will allow the lowest lying Gamow-Teller states to be located in $^{51, 52, 53}$Ca, and the still unknown properties of natural parity states to be investigated. The awaited results should allow to settle the n-n interaction in the fp shell and the Gnp matrix accross the sd and fp shells, one step farther from stability, by comparison with fu...

  12. Core-shell structure of polypyrrole grown on V{sub 2}O{sub 5} nanoribbon as high performance anode material for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Qu, Qunting [New Energy and Materials Laboratory (NEML), Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai (China); School of Energy, Soochow University, Suzhou, Jiangsu (China); Zhu, Yusong; Gao, Xiangwen; Wu, Yuping [New Energy and Materials Laboratory (NEML), Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai (China)

    2012-08-15

    A core-shell structure of polypyrrole grown on V{sub 2}O{sub 5} nanoribbons as a high performance anode material for supercapacitors is fabricated using anionic dodecylbenzenesulfonate (DBS{sup -}) as surfactant. Benefiting from the nanoribbon morphology of V{sub 2}O{sub 5}, the improved charge-transfer and polymeric coating effect of PPy, PPy rate at V{sub 2}O{sub 5} nanocomposites exhibits high energy density, and excellent cycling and rate capability in K{sub 2}SO{sub 4} aqueous electrolyte. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. A Prussian Blue-Based Core-Shell Hollow-Structured Mesoporous Nanoparticle as a Smart Theranostic Agent with Ultrahigh pH-Responsive Longitudinal Relaxivity.

    Science.gov (United States)

    Cai, Xiaojun; Gao, Wei; Ma, Ming; Wu, Meiying; Zhang, Linlin; Zheng, Yuanyi; Chen, Hangrong; Shi, Jianlin

    2015-11-04

    Novel core-shell hollow mesoporous Prussian blue @ Mn-containing Prussian blue analogue (HMPB@MnPBA) nanoparticles, designated as HMPB-Mn) as an intelligent theranostic nanoagent, are successfully constructed by coating a similarly crystal-structured MnPBA onto HMPB. This can be used as a pH-responsive T1 -weighted magnetic resonance imaging contrast agent with ultrahigh longitudinal relaxivity (r1 = 7.43 m m(-1) s(-1) ), and achieves the real-time monitoring of drug release. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. The sustained-release behavior and in vitro and in vivo transfection of pEGFP-loaded core-shell-structured chitosan-based composite particles

    Directory of Open Access Journals (Sweden)

    Wang Y

    2014-10-01

    Full Text Available Yun Wang,1 Fu-xing Lin,2 Yu Zhao,1 Mo-zhen Wang,2 Xue-wu Ge,2 Zheng-xing Gong,1 Dan-dan Bao,1 Yu-fang Gu1 1Department of Plastic Surgery, First Affiliated Hospital of Anhui Medical University, 2CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui, People’s Republic of China Abstract: 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. Keywords: gene therapy, gene transfection, hydroxybutyl chitosan, thiolated N-alkylated chitosan, pEGFP, complex coacervation

  15. Investigation of the structure of core-coupled odd-proton copper nuclei in fpg valence space using the projected shell model

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Anuradha; Singh, Suram; Bharti, Arun [University of Jammu, Department of Physics and Electronics, Jammu (India); Khosa, S.K. [Central University of Jammu, Department of Physics and Astronomical Sciences, Jammu (India); Bhat, G.H.; Sheikh, J.A. [University of Kashmir, Department of Physics, Srinagar (India)

    2017-01-15

    By employing a systematically parametrized Hamiltonian and the best fit of the various input parameters, high-spin yrast energy states for an isotopic chain of odd mass {sup 59-69}Cu nuclei have been investigated by using a novel computational quantum mechanical framework-projected shell model. Comparison of calculations and experiments yields good agreement. The present study of various intriguing nuclear structure properties along the yrast lines in these odd proton isotopes reflects some interesting informative nuclear physics results. The calculations successfully describe the formation of the yrast level structures from multi-quasi-particle configurations based on πf x νg bands for {sup 59-69}Cu isotopes. The present calculations indicate the evolution of the nuclear structure near the magic nuclei, Ni, and also provide an indication of coexistence of both, collective as well as single-particle, levels for {sup 69}Cu nucleus at N=40. (orig.)

  16. Application of Ni-Oxide@TiO₂ Core-Shell Structures to Photocatalytic Mixed Dye Degradation, CO Oxidation, and Supercapacitors.

    Science.gov (United States)

    Lee, Seungwon; Lee, Jisuk; Nam, Kyusuk; Shin, Weon Gyu; Sohn, Youngku

    2016-12-20

    Performing diverse application tests on synthesized metal oxides is critical for identifying suitable application areas based on the material performances. In the present study, Ni-oxide@TiO₂ core-shell materials were synthesized and applied to photocatalytic mixed dye (methyl orange + rhodamine + methylene blue) degradation under ultraviolet (UV) and visible lights, CO oxidation, and supercapacitors. Their physicochemical properties were examined by field-emission scanning electron microscopy, X-ray diffraction analysis, Fourier-transform infrared spectroscopy, and UV-visible absorption spectroscopy. It was shown that their performances were highly dependent on the morphology, thermal treatment procedure, and TiO₂ overlayer coating.

  17. Study of neutron shell structure of even-even 40-56Ca isotopes by the dispersive optical model

    International Nuclear Information System (INIS)

    Bespalova, O.V.; Boboshin, I.N.; Varlamov, V.V.; Ermakova, T.A.; Ishkhanov, B.S.; Romanovskij, E.A.; Spasskaya, T.I.; Timokhina, T.P.

    2005-01-01

    The single-particle energies and occupation probabilities of the bound neutron states in 40,42,44,46,48 Ca isotopes were obtained by the joint evaluation of the stripping and pick-up reaction data. The results were analyzed by the dispersive optical model and a good agreement was achieved. The dispersive optical potential was extrapolated to unstable 50,52,54,56 Ca nuclei. The calculated single-particle energies of the bound neutron states in unstable Ca isotopes were compared with the nuclear shell-model calculations, which predicted new magic number N = 34 for nuclei with Z = 20 [ru

  18. Wigner’s phase-space function and atomic structure: II. Ground states for closed-shell atoms

    DEFF Research Database (Denmark)

    Springborg, Michael; Dahl, Jens Peder

    1987-01-01

    We present formulas for reduced Wigner phase-space functions for atoms, with an emphasis on the first-order spinless Wigner function. This function can be written as the sum of separate contributions from single orbitals (the natural orbitals). This allows a detailed study of the function. Here we...... display and analyze the function for the closed-shell atoms helium, beryllium, neon, argon, and zinc in the Hartree-Fock approximation. The quantum-mechanical exact results are compared with those obtained with the approximate Thomas-Fermi description of electron densities in phase space....

  19. Core-Shell-Structured Copolyaniline-Coated Polymeric Nanoparticle Suspension and Its Viscoelastic Response under Various Electric Fields

    Directory of Open Access Journals (Sweden)

    Il-Jae Moon

    2015-08-01

    Full Text Available Semi-conducting poly(n-methylaniline (PNMA-coated poly(methyl methacrylate (PMMA composite nanoparticles were synthesized using cross-linked and grafted PMMA particles as a core, and then, the PNMA shell was coated via chemical oxidative polymerization on the surface of modified PMMA nanoparticles. Their electroresponsive electrorheological characteristics when dispersed in silicone were confirmed under applied electric fields using a rotational rheometer, focusing on their viscoelastic response. Using a frequency sweep test, the frequency dependence of both the storage and loss moduli was confirmed to increase upon increasing the electric field, with a stable plateau regime over the entire angular frequency range.

  20. Fabrication of Core-Shell Structural SiO2@H3[PM12O40] Material and Its Catalytic Activity

    Directory of Open Access Journals (Sweden)

    Xin Yang

    2014-01-01

    Full Text Available Through a natural tree grain template and sol-gel technology, the heterogeneous catalytic materials based on polyoxometalate compounds H3[PM12O40] encapsulating SiO2: SiO2@H3[PM12O40] (SiO2@PM12, M = W, Mo with core-shell structure had been prepared. The structure and morphology of the core-shell microspheres were characterized by the XRD, IR spectroscopy, UV-Vis absorbance, and SEM. These microsphere materials can be used as heterogeneous catalysts with high activity and stability for catalytic wet air oxidation of pollutant dyes safranine T (ST at room condition. The results show that the catalysts have excellent catalytic activity in treatment of wastewater containing 10 mg/L ST, and 94% of color can be removed within 60 min. Under different cycling runs, it is shown that the catalysts are stable under such operating conditions and the leaching tests show negligible leaching effect owing to the lesser dissolution.

  1. Crystallization and preliminary x-ray structure analysis of the egg-white lysozyme from a Taiwanese Soft-Shelled Turtle (Tri onyx Sinensis Wiegmann)

    International Nuclear Information System (INIS)

    Siritapetawee, Jaruwan; Thammasirirak, Sompong; Yuvaniyama, Jirudon

    2005-10-01

    Lysozyme has been purified from the egg-white of a Taiwanese soft-shelled turtle. This soft-shelled turtle ' s egg-white lysozyme migrated on 12.5% SDS-PAGE at about 14.8 kDa. The lysozyme has been crystallized using the sitting drop vapor diffusion technique and 30% (w/v) polyethylene glycol 8000 in 0.1 M sodium cacodylate, p H 6.5 containing 0.2 M ammonium sulfate as a precipitant. One of the crystals diffracted X rays beyond 2 angstrom unit resolution and belonged to the orthorhombic, space group P212121, with unit cell dimensions of a = 37.8 angstrom unit, b = 55.6 angstrom unit, and c 72.2 angstrom unit and one molecule of the enzyme per asymmetric unit. The data were collected to 1.9 angstrom resolution with an R merge of 4.6%, suitable for high resolution structure analysis. The single-crystal X-ray structure of lysozyme has been initially phased with the Molecular Replacement technique using pheasant egg-white lysozyme (PDB ID 1GHL) as a search template. Model rebuilding and refinement are in progress

  2. Alginate/nanohydroxyapatite scaffolds with designed core/shell structures fabricated by 3D plotting and in situ mineralization for bone tissue engineering.

    Science.gov (United States)

    Luo, Yongxiang; Lode, Anja; Wu, Chengtie; Chang, Jiang; Gelinsky, Michael

    2015-04-01

    Composite scaffolds, especially polymer/hydroxyapatite (HAP) composite scaffolds with predesigned structures, are promising materials for bone tissue engineering. Various methods including direct mixing of HAP powder with polymers or incubating polymer scaffolds in simulated body fluid for preparing polymer/HAP composite scaffolds are either uncontrolled or require long times of incubation. In this work, alginate/nano-HAP composite scaffolds with designed pore parameters and core/shell structures were fabricated using 3D plotting technique and in situ mineralization under mild conditions (at room temperature and without the use of any organic solvents). Light microscopy, scanning electron microscopy, microcomputer tomography, X-ray diffraction, and Fourier transform infrared spectroscopy were applied to characterize the fabricated scaffolds. Mechanical properties and protein delivery of the scaffolds were evaluated, as well as the cell response to the scaffolds by culturing human bone-marrow-derived mesenchymal stem cells (hBMSC). The obtained data indicate that this method is suitable to fabricate alginate/nano-HAP composite scaffolds with a layer of nano-HAP, coating the surface of the alginate strands homogeneously and completely. The surface mineralization enhanced the mechanical properties and improved the cell attachment and spreading, as well as supported sustaining protein release, compared to pure alginate scaffolds without nano-HAP shell layer. The results demonstrated that the method provides an interesting option for bone tissue engineering application.

  3. Effect of nitrogen on the electrochemical performance of core–shell structured Si/C nanocomposites as anode materials for Li-ion batteries

    International Nuclear Information System (INIS)

    Tao, Hua-Chao; Huang, Mian; Fan, Li-Zhen; Qu, Xuanhui

    2013-01-01

    Highlights: ► N-containing core–shell structured Si/C nanocomposites are prepared via two steps. ► The N-containing Si/C nanocomposites exhibit high capacity and excellent cycling stability. ► The appropriate nitrogen has a beneficial effect on the electrochemical performance. -- Abstract: Core–shell structured Si/C nanocomposites with different nitrogen contents are prepared by in situ polymerization of aniline in the suspension of silicon nanoparticles followed by carbonization of Si/polyaniline (PANI) nanocomposites at different temperatures. The nitrogen contents of Si/C nanocomposites decrease gradually with increasing carbonization temperatures. The effect of nitrogen contents on the electrochemical performance of Si/C nanocomposites as anode materials for lithium ion batteries is investigated. It is found that the Si/C nanocomposites with 4.75 wt.% nitrogen exhibit the high specific capacity of 795 mAh g −1 after 50 cycles at a current density of 100 mA g −1 and excellent cycling stability. The appropriate nitrogen in Si/C nanocomposites plays a beneficial role in the improvement of electrochemical performance. The nitrogen in Si/C nanocomposites increases the reversible capacity, which may be due to the formation of vacancies and dangling bonds around the nitrogen sites

  4. 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

  5. Pressure Shell Approach to Integrated Environmental Protection

    Science.gov (United States)

    Kennedy, Kriss J.

    2011-01-01

    The next generation of exploration mission human systems will require environmental protection such as radiation protection that is effective and efficient. In order to continue human exploration, habitat systems will require special shells to protect astronauts from hostile environments. The Pressure Shell Approach to integrated environmental (radiation) protection is a multi-layer shell that can be used for multifunctional environmental protection. Self-healing, self-repairing nano technologies and sensors are incorporated into the shell. This shell consists of multiple layers that can be tailored for specific environmental protection needs. Mainly, this innovation focuses on protecting crew from exposure to micrometeorites, thermal, solar flares, and galactic cosmic ray (GCR) radiation. The Pressure Shell Approach consists of a micrometeoroid and secondary ejecta protection layer; a thin, composite shell placed in between two layers that is non-structural; an open cavity layer that can be filled with water, regolith, or polyethylene foam; a thicker composite shell that is a structural load bearing that is placed between two layers; and a bladder coating on the interior composite shell. This multi-layer shell creates an effective radiation protection system. Most of its layers can be designed with the materials necessary for specific environments. In situ materials such as water or regolith can be added to the shell design for supplemental radiation protection.

  6. Bridging quantum chemistry and nuclear structure theory: Coupled-cluster calculations for closed- and open-shell nuclei

    International Nuclear Information System (INIS)

    Piecuch, Piotr; Wloch, Marta; Gour, Jeffrey R.; Dean, David J.; Papenbrock, Thomas; Hjorth-Jensen, Morten

    2005-01-01

    We review basic elements of the single-reference coupled-cluster theory and discuss large scale ab initio calculations of ground and excited states of 15O, 16O, and 17O using coupled-cluster methods and algorithms developed in quantum chemistry. By using realistic two-body interactions and the renormalized form of the Hamiltonian obtained with a no-core G-matrix approach, we obtain the converged results for 16O and promising preliminary results for 15O and 17O at the level of two-body interactions. The calculated properties other than energies include matter density, charge radius, and charge form factor. The relatively low costs of coupled-cluster calculations, which are characterized by the low-order polynomial scaling with the system size, enable us to probe large model spaces with up to 7 or 8 major oscillator shells, for which non-truncated shell-model calculations for nuclei with A = 15 17 active particles are presently not possible. We argue that the use of coupled-cluster methods and computer algorithms developed by quantum chemists to calculate properties of nuclei is an important step toward the development of accurate and affordable many-body theories that cross the boundaries of various physical sciences

  7. Fabrication of Cu-Ag core-shell bimetallic superfine powders by eco-friendly reagents and structures characterization

    Science.gov (United States)

    Zhao, Jun; Zhang, Dongming; Zhao, Jie

    2011-09-01

    Superfine bimetallic Cu-Ag core-shell powders were synthesized by reduction of copper sulfate pentahydrate and silver nitrate with eco-friendly ascorbic acid as a reducing agent and cyclodextrins as a protective agent in an aqueous system. The influence of Ag/Cu ratio on coatings was investigated. Ag was homogeneously distributed on the surface of Cu particles at a mole ratio of Ag/Cu=1. FE-SEM showed an uniformity of Ag coatings on Cu particles. Antioxidation of Cu particles was improved by increasing Ag/Cu ratio. TEM-EDX and UV-vis spectra also revealed that Cu cores were covered by Ag nanoshells on the whole. The surface composition analysis by XPS indicated that only small parts of Cu atoms in the surface were oxidized. It was noted that the hindrance of cyclodextrins chemisorbed on particles plays an important role in forming high quality and good dispersity Cu-Ag (Cu@Ag) core-shell powders.

  8. Band structure of Si/Ge core-shell nanowires along the [110] direction modulated by external uniaxial strain

    International Nuclear Information System (INIS)

    Peng Xihong; Tang Fu; Logan, Paul

    2011-01-01

    Strain modulated electronic properties of Si/Ge core-shell nanowires along the [110] direction were reported, on the basis of first principles density-functional theory calculations. In particular, the energy dispersion relationship of the conduction/valence band was explored in detail. At the Γ point, the energy levels of both bands are significantly altered by applied uniaxial strain, which results in an evident change of the band gap. In contrast, for the K vectors far away from Γ, the variation of the conduction/valence band with strain is much reduced. In addition, with a sufficient tensile strain (∼1%), the valence band edge shifts away from Γ, which indicates that the band gap of the Si/Ge core-shell nanowires experiences a transition from direct to indirect. Our studies further showed that effective masses of charge carriers can also be tuned using the external uniaxial strain. The effective mass of the hole increases dramatically with tensile strain, while strain shows a minimal effect on tuning the effective mass of the electron. Finally, the relation between strain and the conduction/valence band edge is discussed thoroughly in terms of site-projected wavefunction characters.

  9. Structural changes in quantum dots core-shell CdSe/ZnS by thermal treatment and proton irradiation

    International Nuclear Information System (INIS)

    Almeida, L.G.; Sortica, M.A.; Grande, P.L.; Debastiani, R.; Dias, J.F.; Hentz, A.; Radtke, C.

    2013-01-01

    Full text: Compound quantum-dots (QDs) are promising materials used in many fields of technological development. In spite of that, the accurate knowledge of their compositional depth-profiling is still a technological challenge. Recently, we used the MEIS (medium energy ion-scattering) technique, combined with PIXE and RBS (Rutherford backscattering spectrometry) to characterize core-shell nanostructures of CdSe/ZnS [1]. In this work, we use the same characterization methods to survey the changes of elemental distribution in the the core and shell regions of these QDs, when submitted to a range of thermal treatments and proton irradiation conditions. Our preliminary results show that for temperatures below the melting point of the bulk CdSe compound, there is already a decrease in the amount of cadmium, accompanied by an overall decrease in the diameter of the CdSe QD nuclei. [1] M. A. Sortica, P. L. Grande, C. Radtke, L. Almeida, R. Debastiani, J. F. Dias, A. Hentz, Applied Physics Letters, 101 (2012)023110. (author)

  10. Synthesis and characterization of organic–inorganic core–shell structure nanocomposite and application for Zn ions removal from aqueous solution in a fixed-bed column

    Energy Technology Data Exchange (ETDEWEB)

    Ghasemi, Shokoofeh [Faculty of Chemical, Gas and Petroleum Engineering, Semnan University, Semnan 35131-19111 (Iran, Islamic Republic of); Ghorbani, Mohsen, E-mail: M.ghorbani@nit.ac.ir [Faculty of Chemical Engineering, Babol University of Technology, P.O. Box 484, Babol (Iran, Islamic Republic of); Ghazi, Mohsen Mehdipour [Faculty of Chemical, Gas and Petroleum Engineering, Semnan University, Semnan 35131-19111 (Iran, Islamic Republic of)

    2015-12-30

    Graphical abstract: - Highlights: • The γ-Fe{sub 2}O{sub 3} nanoparticles were prepared in one step using ultrasonic radiation and coated by polyrhodanine. • Nanocomposite synthesized with core average diameter of 15 nm and polyrhodanine as shell with thickness of 1.5 nm • Application of products was investigated to separate zinc ions from aqueous solution in a fixed-bed column. • The Adams–Bohart, BDST, Thomas and Yoon–Nelson models used to predict model parameters. • The models were nearly in good agreement with the experimental data. - Abstract: An organic–inorganic core/shell structure, γ-Fe{sub 2}O{sub 3}/polyrhodanine nanocomposite with γ-Fe{sub 2}O{sub 3} nanoparticle as core with average diameter of 15 nm and polyrhodanine as shell with thickness of 1.5 nm, has been synthesized via chemical oxidation polymerization and applied for adsorption of Zn ions from aqueous solution in a fixed-bed column. The properties of nanocomposite were characterized with transmission electron microscope (TEM), Fourier transform infrared (FT-IR) spectroscopy and vibrating sample magnetometer (VSM). The performance of the column was assessed under variable bed heights (10, 15 and 20 cm) and influent Zn concentrations (50, 100 and 150 ppm) at a constant flow rate (0.5 mL/min). The results demonstrated that the breakthrough curves are S-shaped and the breakthrough time increases with increasing bed height and decreases with increasing influent concentration. Moreover, the dynamics of the adsorption process were evaluated by using Adams–Bohart, bed depth service time (BDST), Thomas and Yoon–Nelson kinetic models. The models were nearly in good agreement with the experimental data.

  11. Recent advances in platinum monolayer electrocatalysts for oxygen reduction reaction: Scale-up synthesis, structure and activity of Pt shells on Pd cores

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, K., E-mail: ksasaki@bnl.go [Brookhaven National Laboratory, Chemistry Department, Upton, NY 11973 (United States); Wang, J.X. [Brookhaven National Laboratory, Chemistry Department, Upton, NY 11973 (United States); Naohara, H. [Toyota Motor Corporation, Susono 410-1193 (Japan); Marinkovic, N. [University of Delaware, Department of Chemical Engineering, Newark, DE 19716 (United States); More, K. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Inada, H. [Hitachi High Technologies America, Pleasanton, CA 94588 (United States); Adzic, R.R., E-mail: adzic@bnl.go [Brookhaven National Laboratory, Chemistry Department, Upton, NY 11973 (United States)

    2010-03-01

    We have established a scale-up synthesis method to produce gram-quantities of Pt monolayer electrocatalysts. The core-shell structure of the Pt/Pd/C electrocatalyst has been verified using the HAADF-STEM Z-contrast images, STEM/EELS, and STEM/EDS line profile analysis. The atomic structure of this electrocatalyst and formation of a Pt monolayer on Pd nanoparticle surfaces were examined using in situ EXAFS. The Pt mass activity of the Pt/Pd/C electrocatalyst for ORR is considerably higher than that of commercial Pt/C electrocatalysts. The results with Pt monolayer electrocatalysts may significantly impact science of electrocatalysis and fuel-cell technology, as they have demonstrated an exceptionally effective way of using Pt that can resolve problems of other approaches, including electrocatalysts' inadequate activity and high Pt content.

  12. A systematic study of band structure and electromagnetic properties of neutron rich odd mass Eu isotopes in the projected shell model framework

    Energy Technology Data Exchange (ETDEWEB)

    Pandit, Rakesh K.; Devi, Rani [University of Jammu, Department of Physics and Electronics, Jammu (India); Khosa, S.K. [Central University of Jammu, Department of Physics and Astronomical Sciences, Jammu (India); Bhat, G.H.; Sheikh, J.A. [University of Kashmir, Department of Physics, Srinagar (India)

    2017-10-15

    The positive and negative parity rotational band structure of the neutron rich odd mass Eu isotopes with neutron numbers ranging from 90 to 96 are investigated up to the high angular momentum. In the theoretical analysis of energy spectra, transition energies and electromagnetic transition probabilities we employ the projected shell model. The calculations successfully describe the formation of the ground and excited band structures from the single particle and multi quasiparticle configurations. Calculated excitation energy spectra, transition energies, exact quantum mechanically calculated B(E2) and B(M1) transition probabilities are compared with experimental data wherever available and a reasonably good agreement is obtained with the observed data. The change in deformation in the ground state band with the increase in angular momentum and the increase in neutron number has also been established. (orig.)

  13. Recent advances in platinum monolayer electrocatalysts for oxygen reduction reaction: Scale-up synthesis, structure and activity of Pt shells on Pd cores

    International Nuclear Information System (INIS)

    Sasaki, K.; Wang, J.X.; Naohara, H.; Marinkovic, N.; More, K.; Inada, H.; Adzic, R.R.

    2010-01-01

    We have established a scale-up synthesis method to produce gram-quantities of Pt monolayer electrocatalysts. The core-shell structure of the Pt/Pd/C electrocatalyst has been verified using the HAADF-STEM Z-contrast images, STEM/EELS, and STEM/EDS line profile analysis. The atomic structure of this electrocatalyst and formation of a Pt monolayer on Pd nanoparticle surfaces were examined using in situ EXAFS. The Pt mass activity of the Pt/Pd/C electrocatalyst for ORR is considerably higher than that of commercial Pt/C electrocatalysts. The results with Pt monolayer electrocatalysts may significantly impact science of electrocatalysis and fuel-cell technology, as they have demonstrated an exceptionally effective way of using Pt that can resolve problems of other approaches, including electrocatalysts' inadequate activity and high Pt content.

  14. De novo assembly of pen shell ( Atrina pectinata) transcriptome and screening of its genic microsatellites

    Science.gov (United States)

    Sun, Xiujun; Li, Dongming; Liu, Zhihong; Zhou, Liqing; Wu, Biao; Yang, Aiguo

    2017-10-01

    The pen shell ( Atrina pectinata) is a large wedge-shaped bivalve, which belongs to family Pinnidae. Due to its large and nutritious adductor muscle, it is the popular seafood with high commercial value in Asia-Pacific countries. However, limiting genomic and transcriptomic data have hampered its genetic investigations. In this study, the transcriptome of A. pectinata was deeply sequenced using Illumina pair-end sequencing technology. After assembling, a total of 127263 unigenes were obtained. Functional annotation indicated that the highest percentage of unigenes (18.60%) was annotated on GO database, followed by 18.44% on PFAM database and 17.04% on NR database. There were 270 biological pathways matched with those in KEGG database. Furthermore, a total of 23452 potential simple sequence repeats (SSRs) were identified, of them the most abundant type was mono-nucleotide repeats (12902, 55.01%), which was followed by di-nucleotide (8132, 34.68%), tri-nucleotide (2010, 8.57%), tetra-nucleotide (401, 1.71%), and penta-nucleotide (7, 0.03%) repeats. Sixty SSRs were selected for validating and developing genic SSR markers, of them 23 showed polymorphism in a cultured population with the average observed and expected heterozygosities of 0.412 and 0.579, respectively. In this study, we established the first comprehensive transcript dataset of A. pectinata genes. Our results demonstrated that RNA-Seq is a fast and cost-effective method for genic SSR development in non-model species.

  15. The hierarchical porous structure bio-char assessments produced by co-pyrolysis of municipal sewage sludge and hazelnut shell and Cu(II) adsorption kinetics.

    Science.gov (United States)

    Zhao, Bing; Xu, Xinyang; Zeng, Fanqiang; Li, Haibo; Chen, Xi

    2018-05-04

    The co-pyrolysis technology was applied to municipal sewage sludge (MSS) and hazelnut shell with alkaline activating agent K 2 CO 3 under N 2 atmosphere. The innovative bio-char produced by co-pyrolysis had significant physical and chemical characteristics. The specific surface area reached 1990.23 m 2 /g, and the iodine absorption number was 1068.22 mg/g after co-pyrolysis at 850 °C. Although hazelnut shell was a kind of solid waste, it also had abundant cellulose resource, which could contribute to porous structure of bio-char during co-pyrolysis with MSS and decrease total heavy metals contents of raw material to increase security of bio-chars. Meanwhile, the residual fractions of heavy metals in bio-char were above 92.95% after co-pyrolysis at 900 °C except Cd to prevent heavy metals digestion, and the bio-char presented significant immobilization behavior from co-pyrolysis technology. Moreover, the yield and the iodine absorption number of bio-chars under different process variables were analyzed, and it was confirmed that appropriate process variables could contribute the yield and the iodine absorption number of bio-char and prevent to etch pore structure excessively to collapse. The changes of surface functional groups and crystallographic structure before and after co-pyrolysis were analyzed by FTIR and XRD, respectively. The hierarchical porous structure of bio-char was presented by SEM and N 2 adsorption-desorption isotherm. The Cu(II) adsorption capacity of the bio-char was 42.28 mg/g after 24 h, and surface functional groups acted as active binding sites for Cu(II) adsorption. Langmuir model and pseudo-second-order model can describe process of Cu(II) adsorption well.

  16. Core-shell structured ceramic nonwoven separators by atomic layer deposition for safe lithium-ion batteries

    Science.gov (United States)

    Shen, Xiu; Li, Chao; Shi, Chuan; Yang, Chaochao; Deng, Lei; Zhang, Wei; Peng, Longqing; Dai, Jianhui; Wu, Dezhi; Zhang, Peng; Zhao, Jinbao

    2018-05-01

    Safety is one of the most factors for lithium-ion batteries (LIBs). In this work, a novel kind of ceramic separator with high safety insurance is proposed. We fabricated the core-shell nanofiber separators for LIBs by atomic layer deposition (ALD) of 30 nm Al2O3 on the electrospinning nonwoven fiber of polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP). The separators show a pretty high heat resistance up to 200 °C without any shrinkage, an excellent fire-resistant property and a wide electrochemical window. Besides, with higher uptake and ionic conductivity, cells assembled with the novel separator shows better electrochemical performance. The ALD produced separators exhibit great potential in elaborate products like 3C communications and in energy field with harsh requirements for safety such as electric vehicles. The application of ALD on polymer fiber membranes brings a new strategy and opportunity for improving the safety of the advanced LIBs.

  17. Structure and photoluminescence properties of ZnS-core/In2O3-shell one-dimensional nanowires

    Science.gov (United States)

    Park, Sunghoon; Lee, Jungkeun; Jeong, Bongyong; Lee, Wan In; Lee, Chongmu

    2011-12-01

    ZnS-core/In2O3-shell nanowires have been prepared by using a two-step process: the thermal evaporation of ZnS powders on Si(100) substrates coated with Au thin films and the sputter-deposition of In2O3. The ZnS nanowires were a few tens to a few hundreds of nanometers in diameter and up to a few hundreds of micrometers in length. ZnS nanowires have an emission band centered at around 570 nm in the yellow region. The yellow emission has been enhanced in intensity by coating the ZnS nanowires with In2O3 and further enhanced by annealing in a reducing atmosphere, but it is degraded by annealing in an oxidative atmosphere.

  18. Structural Properties of Zn-ZnO Core-Shell Microspheres Grown by Hot-Filament CVD Technique

    Directory of Open Access Journals (Sweden)

    R. López

    2012-01-01

    Full Text Available We report the hot-filament chemical vapor deposition (HFCVD growth of Zn-ZnO core-shell microspheres in the temperature range of 350–650°C only using ZnO pellets as raw material. The samples were characterized by scanning electron microscope (SEM, energy dispersive spectroscopy (EDS, and X-ray diffraction (XRD techniques. SEM micrographs showed the presence of solid microspheres and a Zn-ZnO layer in all samples. The observed heterogeneous morphology on each sample suggested two different growth mechanisms. On the one hand, solid microspheres were formed by means of gas phase nucleation of Zn atoms. The Zn-ZnO layer was formed on the substrate as result of surface reactions. It is possible that Zn microspheres condensed during the natural cooling of the HFCVD reactor as they were observed on the Zn-ZnO layer.

  19. Pt monolayer shell on hollow Pd core electrocatalysts: Scale up synthesis, structure, and activity for the oxygen reduction reaction

    Directory of Open Access Journals (Sweden)

    Vukmirovic Miomir B.

    2013-01-01

    Full Text Available We report on synthesis, characterization and the oxygen reduction reaction (ORR kinetics of Pt monolayer shell on Pd(hollow, or Pd-Au(hollow core electrocatalysts. Comparison between the ORR catalytic activity of the electrocatalysts with hollow cores and those of Pt solid and Pt hollow nanoparticles has been obtained using the rotating disk electrode technique. Hollow nanoparticles were made using Ni or Cu nanoparticles as sacrificial templates. The Pt ORR specific and mass activities of the electrocatalysts with hollow cores were found considerably higher than those of the electrocatalysts with the solid cores. We attribute this enhanced Pt activity to the smooth surface morphology and hollow-induced lattice contraction, in addition to the mass-saving geometry of hollow particles.

  20. 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

  1. On-demand oil-water separation via low-voltage wettability switching of core-shell structures on copper substrates

    Science.gov (United States)

    Kung, Chun Haow; Zahiri, Beniamin; Sow, Pradeep Kumar; Mérida, Walter

    2018-06-01

    A copper mesh with dendritic copper-oxide core-shell structure is prepared using an additive-free electrochemical deposition strategy for on-demand oil-water separation. Electrochemical manipulation of the oxidation state of the copper oxide shell phase results in opposite affinities towards water and oil. The copper mesh can be tuned to manifest both superhydrophobic and superoleophilic properties to enable oil-removal. Conversely, switching to superhydrophilic and underwater superoleophobic allows water-removal. These changes correspond to the application of small reduction voltages (air drying. In the oil-removal mode, heavy oil selectively passes through the mesh while water is retained; in water-removal mode, the mesh allows water to permeate but blocks light oil. The smart membrane achieved separation efficiencies higher than 98% for a series of oil-water mixtures. The separation efficiency remains high with less than 5% variation after 30 cycles of oil-water separation in both modes. The switchable wetting mechanism is demonstrated with the aid of microstructural and electrochemical analysis and based on the well-known Cassie-Baxter and Wenzel theories. The selective removal of water or oil from the oil-water mixtures is driven solely by gravity and yields high efficiency and recyclability. The potential applications for the relevant technologies include oil spills cleanup, fuel purification, and wastewater treatment.

  2. Enhanced energy density and thermostability in polyimide nanocomposites containing core-shell structured BaTiO3@SiO2 nanofibers

    Science.gov (United States)

    Wang, Junchuan; Long, Yunchen; Sun, Ying; Zhang, Xueqin; Yang, Hong; Lin, Baoping

    2017-12-01

    High energy density polymer nanocomposites with high-temperature resistance are quite desirable for film capacitors and many other power electronics. In this study, polyimide-based (PI) nanocomposite films containing the core-shell structured barium titanate@silicon dioxide (BT@SiO2) nanofibers have been successfully synthesized by the solution casting method. In the BT@SiO2/PI nanocomposite films, the dielectric permittivity as well as the breakdown strength increase significantly. The SiO2 shell layers with moderate dielectric permittivity could effectively mitigate the local field concentration induced by the large mismatch between the dielectric permittivity of BT and PI, which contributes to the enhancement of the breakdown strength of the PI nanocomposite films. As a result, the PI nanocomposite film filled with 3 vol% BT@SiO2 nanofibers exhibits a maximal energy density of 2.31 J cm-3 under the field of 346 kV/mm, which is 62% over the pristine PI (1.42 J cm-3 at 308 kV/mm) and about 200% greater than the best commercial polymer, i.e. biaxially oriented polypropylenes (BOPP) (≈1.2 J cm-3). The thermogravimetric analysis results indicate that the BT@SiO2/PI nanocomposite films have good thermal stability below 500 °C.

  3. Low-Cost Label-Free Biosensing Bimetallic Cellulose Strip with SILAR-Synthesized Silver Core-Gold Shell Nanoparticle Structures.

    Science.gov (United States)

    Kim, Wansun; Lee, Jae-Chul; Lee, Gi-Ja; Park, Hun-Kuk; Lee, Anbok; Choi, Samjin

    2017-06-20

    We introduce a label-free biosensing cellulose strip sensor with surface-enhanced Raman spectroscopy (SERS)-encoded bimetallic core@shell nanoparticles. Bimetallic nanoparticles consisting of a synthesis of core Ag nanoparticles (AgNP) and a synthesis of shell gold nanoparticles (AuNPs) were fabricated on a cellulose substrate by two-stage successive ionic layer absorption and reaction (SILAR) techniques. The bimetallic nanoparticle-enhanced localized surface plasmon resonance (LSPR) effects were theoretically verified by computational calculations with finite element models of optimized bimetallic nanoparticles interacting with an incident laser source. Well-dispersed raspberry-like bimetallic nanoparticles with highly polycrystalline structure were confirmed through X-ray and electron analyses despite ionic reaction synthesis. The stability against silver oxidation and high sensitivity with superior SERS enhancement factor (EF) of the low-cost SERS-encoded cellulose strip, which achieved 3.98 × 10 8 SERS-EF, 6.1%-RSD reproducibility, and <10%-degraded sustainability, implicated the possibility of practical applications in high analytical screening methods, such as single-molecule detection. The remarkable sensitivity and selectivity of this bimetallic biosensing strip in determining aquatic toxicities for prohibited drugs, such as aniline, sodium azide, and malachite green, as well as monitoring the breast cancer progression for urine, confirmed its potential as a low-cost label-free point-of-care test chip for the early diagnosis of human diseases.

  4. High Photocatalytic Activity of Fe3O4-SiO2-TiO2 Functional Particles with Core-Shell Structure

    Directory of Open Access Journals (Sweden)

    Chenyang Xue

    2013-01-01

    Full Text Available This paper describes a novel method of synthesizing Fe3O4-SiO2-TiO2 functional nanoparticles with the core-shell structure. The Fe3O4 cores which were mainly superparamagnetic were synthesized through a novel carbon reduction method. The Fe3O4 cores were then modified with SiO2 and finally encapsulated with TiO2 by the sol-gel method. The results of characterizations showed that the encapsulated 700 nm Fe3O4-SiO2-TiO2 particles have a relatively uniform size distribution, an anatase TiO2 shell, and suitable magnetic properties for allowing collection in a magnetic field. These magnetic properties, large area, relative high saturation intensity, and low retentive magnetism make the particles have high dispersibility in suspension and yet enable them to be recovered well using magnetic fields. The functionality of these particles was tested by measuring the photocatalytic activity of the decolouring of methyl orange (MO and methylene blue (MB under ultraviolet light and sunlight. The results showed that the introduction of the Fe3O4-SiO2-TiO2 functional nanoparticles significantly increased the decoloration rate so that an MO solution at a concentration of 10 mg/L could be decoloured completely within 180 minutes. The particles were recovered after utilization, washing, and drying and the primary recovery ratio was 87.5%.

  5. A yolk-shell V2O5 structure assembled from ultrathin nanosheets and coralline-shaped carbon as advanced electrodes for a high-performance asymmetric supercapacitor.

    Science.gov (United States)

    Xing, Ling-Li; Zhao, Gang-Gang; Huang, Ke-Jing; Wu, Xu

    2018-02-13

    Various V 2 O 5 three-dimensional nanostructures are synthesized using a facile template-free hydrothermal method and evaluated for use as supercapacitor electrode materials. As a result, the yolk-shell structure assembled from ultrathin nanosheets shows the best electrochemical performance, with a specific capacitance of 704.17 F g -1 at 1.0 A g -1 and a high capacity retention of 89% over 4000 cycles at 3.0 A g -1 . In addition, a continuous three-dimensional porous coralline-shaped carbon is synthesized from osmanthus and has a large Brunauer-Emmett-Teller surface area of 2840.88 m 2 g -1 . Then, an asymmetric supercapacitor is developed using the as-prepared yolk-shell V 2 O 5 as a positive electrode and the osmanthus derived coralline-shaped carbon as a negative electrode. This exhibits an energy density of 29.49 W h kg -1 at a power density of 800 W kg -1 with a good cycling performance that retains 90.6% of its initial capacity after 2000 cycles at 3.0 A g -1 . Furthermore, two cells in series can easily brightly light up a light-emitting diode (3 V), further demonstrating the great potential of the prepared materials for high-performance supercapacitor devices.

  6. 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.

  7. Synthesis and luminescent properties of CaCO3:Eu3+@SiO2 phosphors with core-shell structure

    Science.gov (United States)

    Liu, Min; Kang, Ming; Chen, Kexu; Mou, Yongren; Sun, Rong

    2018-03-01

    Integrating the processes of preparation of CaCO3:Eu3+ and its surface-coating, core-shell structured CaCO3:Eu3+@SiO2 phosphors with red emission were synthesized by the carbonation method and surface precipitation procedure using sodium silicate as silica source. The phase structure, thermal stability, morphology and luminescent property of the as-synthesized samples were characterized by X-ray diffraction, Fourier transform infrared spectrum, thermal analysis, field-emission scanning electron microscopy, transmission electron microscope and photoluminescence spectra. The experimental results show that Eu3+ ions as the luminescence center are divided into two types: one is at the surface of the CaCO3 and the other inhabits the site of Ca2+. For CaCO3:Eu3+@SiO2 phosphors, the SiO2 layers are continuously coated on the surface of CaCO3:Eu3+ and show a typical core-shell structure. After coated with SiO2 layer, the luminous intensity and the compatibility with the rubber matrix increase greatly. Additionally, the luminous intensity increases with the increasing of Eu3+ ions concentration in CaCO3 core and concentration quenching occurs when Eu3+ ions concentration exceeds 7.0 mol%, while it is 5.0 mol% for CaCO3:Eu3+ phosphors. Therefore, preparation of CaCO3:Eu3+@SiO2 phosphors can not only simplify the experimental process through integrating the preparation of CaCO3:Eu3+ and SiO2 layer, but also effectively increase the luminous intensities of CaCO3:Eu3+ phosphors. The as-obtained phosphors may have potential applications in the fields of optical materials and functional polymer composite materials, such as plastics and rubbers.

  8. A scalable route to prepare core–shell structured ZnO@PEDOT nanowires and PEDOT nanotubes and their properties as electrode materials

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Fang, E-mail: 270220943@qq.com [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Zhang, Xianhong, E-mail: zxh_0507@126.com [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Yang, Le, E-mail: 13613513412@126.com [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Xu, Dehong, E-mail: dedehenry@qq.com [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Ma, Yuhong, E-mail: mayh@mail.buct.edu.cn [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Chen, Dong, E-mail: chendong@mail.buct.edu.cn [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Wang, Li, E-mail: lwang@mail.buct.edu.cn [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Zhao, Changwen, E-mail: zhaocw@mail.buct.edu.cn [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Yang, Wantai, E-mail: yangwt@mail.buct.edu.cn [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China)

    2016-05-01

    Highlights: • ZnO@PEDOT nanowires and PEDOT nanotubes synthesized by chemical oxidation polymerization. • By controlling the ratio of ZnO/EDOT, ZnO@PEDOT formed different structures. • The maximum specific capacitance of PEDOT can reach 101.34 F/g. - Abstract: A composite of a core–shell structured nanowires with ZnO as a core and conductive poly(3,4-ethylenedioxythiophene) (PEDOT) as a shell was prepared. At first, the hexagonal ZnO nanowires, with diameter of about 80–100 nm and length 4–5 μm, were fabricated by hydrothermal synthesis process. Then a thick layer of poly(trifluoroethyl methacrylate)-block-poly(sodium styrene sulfonate) (PTFEMA-b-PSSNa) was grafted from the surface of ZnO nanowires via atom transfer free radical polymerization. At last, with the ZnO@PTFEMA-b-PSSNa as a template and the PSSNa chain as the counterion dopant, PEDOT was precipitated onto the surface of the template to form the composite of ZnO@PEDOT/PSSNa. With the evaluation of the EDOT polymerization, the thickness of the PEDOT layer increased steadily. However, as the ratio of EDOT/ZnO was greater than 1:2, the ZnO nanowires templates were dissolved at last and then PEDOT particles were produced due to increasing of the acidity during the oxidation polymerization of EDOT. In this case, the product was the mixture of the nanotubes and particles of PEDOT/PPSNa. The electrochemical capacitances of the composites with different structures were investigated with cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy techniques with three-electrode cell configuration. The maximum specific capacitance of ZnO@PEDOT electrode can reach 101.34 F/g at 20 mV/s.

  9. Core–shell structure carbon coated ferric oxide (Fe{sub 2}O{sub 3}@C) nanoparticles for supercapacitors with superior electrochemical performance

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Yipeng [School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006 (China); Zhang, Haiyan [School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006 (China); Guangdong Provincial Key Laboratory of Functional Soft Condensed Matter, Guangzhou 510006 (China); Chen, Yiming, E-mail: chenym@gdut.edu.cn [School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006 (China); Guangdong Provincial Key Laboratory of Functional Soft Condensed Matter, Guangzhou 510006 (China); Deng, Peng; Huang, Zhikun [School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006 (China); Liu, Liying; Qian, Yannan; Li, Yunyong [School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006 (China); Guangdong Provincial Key Laboratory of Functional Soft Condensed Matter, Guangzhou 510006 (China); Li, Qingyu [School of Chemistry and Chemistry Engineering, Guangxi Normal University, Guilin 541004 (China)

    2015-08-05

    Highlights: • Fe{sub 2}O{sub 3}@C was prepared by using arc discharge method followed by heat treatment. • KOH activation made the core–shell structure Fe{sub 2}O{sub 3}@C porous. • The activated-Fe{sub 2}O{sub 3}@C supercapacitor exhibited superior electrochemical performance. - Abstract: Core–shell structure carbon coated ferric oxide nanoparticles (Fe{sub 2}O{sub 3}@C) were fabricated by the oxidation of carbon coated iron nanoparticles (Fe@C) prepared by a direct current carbon arc discharge method. Porous activated-Fe{sub 2}O{sub 3}@C was prepared by KOH activation of Fe{sub 2}O{sub 3}@C at the temperature of 750 °C. X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were employed to characterize the structure and morphology of the Fe{sub 2}O{sub 3}@C and activated-Fe{sub 2}O{sub 3}@C. The specific surface area and pore size distribution of the samples were also tested. The activated-Fe{sub 2}O{sub 3}@C electrodes exhibited good electrochemical performance with a maximum specific capacitance of 612 F g{sup −1} at the charge/discharge current density of 0.5 A g{sup −1} with 5 M NaOH electrolyte. After 10,000 cycling DC tests at the charge/discharge current density of 4 A g{sup −1}, a high level specific capacitance of 518 F g{sup −1} was obtained (90.6% retention of the initial capacity), suggesting excellent long-term cycling stability.

  10. Structure, energetic and phase transition of multi shell icosahedral bimetallic nanostructures: A molecular dynamics study of NimPdn (n + m = 55 and 147)

    International Nuclear Information System (INIS)

    Hewage, Jinasena W.

    2015-01-01

    Structure, energetic and thermodynamic properties of multi shell icosahedral bimetallic nickel–palladium nanostructures with the size of 55 and 147 atoms were studied by using the molecular dynamics simulations and the microcanonical ensemble version of multiple histogram method. In 55 atoms icosahedra, two core–shell motifs, Ni 13 Pd 42 and Pd 13 Ni 42 with their isomers Pd 13 (Pd 29 Ni 13 ) and Ni 13 (Ni 29 Pd 13 ) were considered. Similarly in 147 atoms icosahedra, all mutations corresponding to the occupations of either nickel atoms or palladium atoms in the core, inner shell or outer shell and their isomers generated by interchanging thirteen core atoms with thirteen atoms of the other type in the inner and outer shells were considered. It is found that the nickel-core clusters are more stable than the palladium-core clusters and cohesive energy increases with the nickel composition. Phase transition of each cluster was studied by means of constant volume heat capacity. The trend in variation of melting temperature is opposite to the energy trend and special increase in melting points was observed for nickel-core isomers compared to the palladium-core isomers. Helmholtz free energy change with temperature for shell to core interchange of thirteen atoms revealed the thermodynamic stability of the formation of Ni core Pd shell structures and the surface segregation of palladium. - Highlights: • Nanostructures of Ni m Pd n clusters for m + n = 55 and 147 have been studied. • Structures favor the formation of nickel-core surrounded by palladium atoms. • In general, it appears the increase of cohesive energy with the nickel composition. • Calculated thermodynamic parameters confirm the energetic results. • Results show also the palladium segregation on the surface

  11. Bending stresses in Facetted Glass Shells

    DEFF Research Database (Denmark)

    Bagger, Anne; Jönsson, Jeppe; Almegaard, Henrik

    2008-01-01

    A shell structure of glass combines a highly effective structural principle with a material of optimal permeability to light. A facetted shell structure has a piecewise plane geometry, and together the facets form an approximation to a curved surface. A distributed load on a plane-based facetted...... structure will locally cause bending moments in the loaded facets. The bending stresses are dependent on the stiffness of the joints. Approximate solutions are developed to estimate the magnitude of the bending stresses. A FE-model of a facetted glass shell structure is used to validate the expressions...

  12. Water-resistant, monodispersed and stably luminescent CsPbBr3/CsPb2Br5 core-shell-like structure lead halide perovskite nanocrystals

    Science.gov (United States)

    Qiao, Bo; Song, Pengjie; Cao, Jingyue; Zhao, Suling; Shen, Zhaohui; Gao, Di; Liang, Zhiqin; Xu, Zheng; Song, Dandan; Xu, Xurong

    2017-11-01

    Lead halide perovskite materials are thriving in optoelectronic applications due to their excellent properties, while their instability due to the fact that they are easily hydrolyzed is still a bottleneck for their potential application. In this work, water-resistant, monodispersed and stably luminescent cesium lead bromine perovskite nanocrystals coated with CsPb2Br5 were obtained using a modified non-stoichiometric solution-phase method. CsPb2Br5 2D layers were coated on the surface of CsPbBr3 nanocrystals and formed a core-shell-like structure in the synthetic processes. The stability of the luminescence of the CsPbBr3 nanocrystals in water and ethanol atmosphere was greatly enhanced by the photoluminescence-inactive CsPb2Br5 coating with a wide bandgap. The water-stable enhanced nanocrystals are suitable for long-term stable optoelectronic applications in the atmosphere.

  13. Structure of 14C via elastic and inelastic neutron scattering from 13C: Measurement, R-matrix analysis, and shell model calculations

    International Nuclear Information System (INIS)

    Resler, D.A.

    1987-03-01

    The specific purpose of this work is to provide a better understanding of the 14 C level structure; the general purpose is to provide the details for using shell model calculations in R-matrix analyses. Using the TOF facilities of the Ohio University Accelerator Laboratory, the elastic and first 3 inelastic differential scattering cross sections for 13 C + n were measured at 69 energies for 4.5 ≤ E/sub n/ ≤ 11 MeV. A multiple scattering code was developed which provided a simulation of the experimental scattering process allowing accurate corrections to the small inelastic data. The integrated 13 C(n,α) 10 Be cross section is estimated. The sequential 2n-decay of 14 C states populated by 13 C + n was observed. A shell model code was developed. Normal and nonnormal parity calculations were made for the lithium isotopes using a new two-body interaction. The results for 5 Li predict the 2s/sub 1/2/ and 1d/sub 5/2/ single-particle states to be located below the 3/2 + state. Similar calculations were made for 13 C, 13 N, and 14 C. Results for 13 C and 13 N show for E/sub x/ 7 Li and 14 C, 2 h-barω calculations were done. Shell model calculations generated the R-matrix parameters for the elastic and first 3 inelastic channels of 13 C + n. After adjusting some energies, the predicted structure generally agrees with experiment for E/sub n/ 13 C + n data were refit to replace R 0 background terms by more realistic broad states and to get better agreement with model calculations. R-matrix fitting of the full data set produced new 14 C level information. For E/sub n/ > 4 MeV (E/sub x/ > 12 MeV), 5 states are given definite J/sup π/ assignments; 3, tentative assignments. 122 refs., 91 figs., 30 tabs

  14. Ancient shell industry at Bet Dwarka island

    Digital Repository Service at National Institute of Oceanography (India)

    Gaur, A.S.; Sundaresh; Patankar, V.

    for the manufacture of beads, bangles, etc. 12 . Shell species found at the sites include T. pyrum (cha nk), Chicoreus ramosus , Fasciolaria trapezium , Cypraea (cowries), Arabica arabica (cowries), Babylonia spirata , dentalium, mussel and Arca... muscles are attached. Average length of a shell can be up to 15 to 20 cm and width 10 ? 15 cm 8 . It provides a unique structure for the manufacture of several bangles from a single shell. The organ ism living inside is also edible...

  15. Seed-mediated photodeposition route to Ag-decorated SiO2@TiO2 microspheres with ideal core-shell structure and enhanced photocatalytic activity

    Science.gov (United States)

    Ma, Jianqi; Guo, Xiaohua; Ge, Hongguang; Tian, Guanghui; Zhang, Qiang

    2018-03-01

    Ag-decorated SiO2@TiO2 microspheres (SiO2@TiO2-Ag) with ideal core-shell structure and enhanced photocatalytic activity were successfully fabricated by combining both coating anatase TiO2 on the surface of SiO2 spheres and subsequent depositing face-centered cubic Ag nanoparticles (NPs) on the coated TiO2 surface via novel sol-gel method and Ag-seed-mediated photodeposition (PD) route, respectively. The morphology, structure, composition and optical properties of the resulting composites were characterized in detail. The results reveal that the monodisperse SiO2 spheres of ∼260 nm were covered uniformly and perfectly by the TiO2 nanoparticle coating layer with the thickness of ca. 55 nm by the novel sol-gel method. Further, homogeneously and highly dispersed Ag NPs with an average size of 8 ± 1.5 nm were strongly anchored onto the TiO2 surface in SiO2@TiO2 core-shell spheres by the modified PD process (Ag-seed-mediated PD route), whereas polydispersed Ag aggregates and detached Ag NPs were irregularly deposited over the TiO2 surface in previous works, which is the inherent problem and has not been effectively solved for depositing noble metal NPs such as Au, Ag, Pt, Pd on TiO2 surface by conventional PD method. The formation mechanism of small and uniformly dispersed Ag NPs with narrow size distribution via the modified PD method is tentatively explained by both nucleation kinetics and growth kinetics. The key reason is that the pre-deposited seeds firmly tethered on SiO2@TiO2 spheres served as nucleation sites and anchoring points for the further nucleation and subsequent growth of Ag via photoreduction of Ag+.

  16. Evolution of the shell structure in medium-mass nuclei: search for the 2d5/2 neutron orbital in 69Ni

    International Nuclear Information System (INIS)

    Moukaddam, M.

    2012-01-01

    The harmonic oscillator shell closure at N=40 in 68 Ni is weak and loses its strength when removing (or adding) pair of protons. Calculations performed in this mass region predict a new island of inversion at N=40 similar to the one at N=20. Using a large valence space, the neutron orbital 2d(5/2) is shown to be a crucial ingredient for the interpretation of the nuclear structure at N ∼40. The neutron 1g(9/2) -2d(5/2) energy difference has been determined in 69 Ni beam at 25.14 MeV/u separated by the LISE3 spectrometer was impinging a CD 2 target of 2.6 mg/cm 2 thickness. The experimental setup consisted of CATS/MUST2-S1/EXOGAM detectors coupled to an ionization chamber and a plastic scintillator. The angular moment and spectroscopic factors of the ground state (J π =9/2 + ) and a doublet of states (J π =5/2 + ) around 2.48 MeV corresponding to the population of the 1g(9/2) and the 2d(5/2) orbitals, were obtained from the comparison between the experimental cross-sections as a function of the proton detection angle and ADWA calculations. The spins of the observed states were assigned by comparison to large scale Shell-Model calculations. The position of the 2d(5/2) orbital in 69 Ni has been established for the first time. Our measurements support the hypothesis of a low-lying 2d(5/2) orbital (∼2.5 MeV) with respect to the 1g(9/2) neutron orbital and thus its major role in the structure of the nuclei around N=40. (author)

  17. Nafion covered core–shell structured Fe{sub 3}O{sub 4}@graphene nanospheres modified electrode for highly selective detection of dopamine

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wuxiang; Zheng, Jianzhong; Shi, Jiangu; Lin, Zhongqiu; Huang, Qitong; Zhang, Hanqiang; Wei, Chan [College of Chemistry and Environment, Minnan Normal University, Zhangzhou 363000 (China); Chen, Jianhua [College of Chemistry and Environment, Minnan Normal University, Zhangzhou 363000 (China); Fujian Province University Key Laboratory of Analytical Science, Minnan Normal University, Zhangzhou 363000 (China); Hu, Shirong, E-mail: Hushirong6666@163.com [College of Chemistry and Environment, Minnan Normal University, Zhangzhou 363000 (China); Fujian Province University Key Laboratory of Analytical Science, Minnan Normal University, Zhangzhou 363000 (China); School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Hao, Aiyou [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China)

    2015-01-01

    Graphical abstract: Schematic illustration of the reaction mechanism of Fe{sub 3}O{sub 4}@GNs/Nafion with DA. - Highlights: • The sensor based on Fe{sub 3}O{sub 4}@graphene nanospheres was prepared for the first time. • The biosensor shows a wide linear range and a lower detection limit of 0.007 μM. • This method was successfully applied to detection of DA in real samples. - Abstract: Nafion covered core–shell structured Fe{sub 3}O{sub 4}@graphene nanospheres (GNs) modified glassy carbon electrode (GCE) was successfully prepared and used for selective detection dopamine. Firstly, the characterizations of hydro-thermal synthesized Fe{sub 3}O{sub 4}@GNs were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. Then Fe{sub 3}O{sub 4}@GNs/Nafion modified electrode exhibited excellent electrocatalytic activity toward the oxidations of dopamine (DA). The interference test showed that the coexisted ascorbic acid (AA) and uric acid (UA) had no electrochemical interference toward DA. Under the optimum conditions, the broad linear relationship was obtained in the experimental concentration from 0.020 μM to 130.0 μM with the detection limit (S/N = 3) of 0.007 μM. Furthermore, the core–shell structured Fe{sub 3}O{sub 4}@GNs/Nafion/GCE was applied to the determination of DA in real samples and satisfactory results were got, which could provide a promising platform to develop excellent biosensor for detecting DA.

  18. [Removal and Recycle of Phosphor from Water Using Magnetic Core/Shell Structured Fe₃O₄ @ SiO₂Nanoparticles Functionalized with Hydrous Aluminum Oxide].

    Science.gov (United States)

    Lai, Li; Xie, Qiang; Fang, Wen-kan; Xing, Ming-chao; Wu, De-yi

    2016-04-15

    A novel magnetic core/shell structured nano-particle Fe₃O₄@ SiO₂phosphor-removal ahsorbent functionalized with hydrous aluminum oxides (Fe₃O₄@ SiO₂@ Al₂O₃· nH₂O) was synthesized. Fe₃O₄@ SiO₂@ Al₂O₃· nH₂O was characterized by XRD, TEM, VSM and BET nitrogen adsorption experiment. The XRD and TEM results demonstrated the presence of the core/shell structure, with saturated magnetization and specific surface area of 56.00 emu · g⁻¹ and 47.27 m² · g⁻¹, respectively. In batch phosphor adsorption experiment, the Langmuir adsorption maximum capacity was 12.90 mg · g⁻¹ and nearly 96% phosphor could be rapidly removed within a contact time of 40 mm. Adsorption of phosphor on Fe₃O₄@ SiO₂@ Al₂O₃ · nH₂O was highly dependent on pH condition, and the favored pH range was 5-9 in which the phosphor removal rate was above 90%. In the treatment of sewage water, the recommended dosage was 1.25 kg · t⁻¹. In 5 cycles of adsorption-regeneration-desorption experiment, over 90% of the adsorbed phosphor could be desorbed with 1 mol · L⁻¹ NaOH, and Fe₃O₄@ SiO₂@ Al₂O₃· nH₂O could be reused after regeneration by pH adjustment with slightly decreased phosphor removal rate with increasing recycling number, which proved the recyclability of Fe₃O₄@ SiO₂@ Al₂O₃· nH₂O and thereby its potential in recycling of phosphor resources.

  19. Core-shell structured polystyrene/BaTiO3 hybrid nanodielectrics prepared by in situ RAFT polymerization: a route to high dielectric constant and low loss materials with weak frequency dependence.

    Science.gov (United States)

    Yang, Ke; Huang, Xingyi; Xie, Liyuan; Wu, Chao; Jiang, Pingkai; Tanaka, Toshikatsu

    2012-11-23

    A novel route to prepare core-shell structured nanocomposites with excellent dielectric performance is reported. This approach involves the grafting of polystyrene (PS) from the surface of BaTiO(3) by an in situ RAFT polymerization. The core-shell structured PS/BaTiO(3) nanocomposites not only show significantly increased dielectric constant and very low dielectric loss, but also have a weak frequency dependence of dielectric properties over a wide range of frequencies. In addition, the dielectric constant of the nanocomposites can also be easily tuned by varying the thickness of the PS shell. Our method is very promising for preparing high-performance nanocomposites used in energy-storage devices. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Composted oyster shell as lime fertilizer is more effective than fresh oyster shell.

    Science.gov (United States)

    Lee, Young Han; Islam, Shah Md Asraful; Hong, Sun Joo; Cho, Kye Man; Math, Renukaradhya K; Heo, Jae Young; Kim, Hoon; Yun, Han Dae

    2010-01-01

    Physio-chemical changes in oyster shell were examined, and fresh and composted oyster shell meals were compared as lime fertilizers in soybean cultivation. Structural changes in oyster shell were observed by AFM and FE-SEM. We found that grains of the oyster shell surface became smoother and smaller over time. FT-IR analysis indicated the degradation of a chitin-like compound of oyster shell. In chemical analysis, pH (12.3+/-0.24), electrical conductivity (4.1+/-0.24 dS m(-1)), and alkaline powder (53.3+/-1.12%) were highest in commercial lime. Besides, pH was higher in composted oyster shell meal (9.9+/-0.53) than in fresh oyster shell meal (8.4+/-0.32). The highest organic matter (1.1+/-0.08%), NaCl (0.54+/-0.03%), and moisture (15.1+/-1.95%) contents were found in fresh oyster shell meal. A significant higher yield of soybean (1.33 t ha(-1)) was obtained by applying composted oyster shell meal (a 21% higher yield than with fresh oyster shell meal). Thus composting of oyster shell increases the utility of oyster shell as a liming material for crop cultivation.

  1. Isogeometric shell formulation based on a classical shell model

    KAUST Repository

    Niemi, Antti

    2012-09-04

    This paper constitutes the first steps in our work concerning isogeometric shell analysis. An isogeometric shell model of the Reissner-Mindlin type is introduced and a study of its accuracy in the classical pinched cylinder benchmark problem presented. In contrast to earlier works [1,2,3,4], the formulation is based on a shell model where the displacement, strain and stress fields are defined in terms of a curvilinear coordinate system arising from the NURBS description of the shell middle surface. The isogeometric shell formulation is implemented using the PetIGA and igakit software packages developed by the authors. The igakit package is a Python package used to generate NURBS representations of geometries that can be utilised by the PetIGA finite element framework. The latter utilises data structures and routines of the portable, extensible toolkit for scientific computation (PETSc), [5,6]. The current shell implementation is valid for static, linear problems only, but the software package is well suited for future extensions to geometrically and materially nonlinear regime as well as to dynamic problems. The accuracy of the approach in the pinched cylinder benchmark problem and present comparisons against the h-version of the finite element method with bilinear elements. Quadratic, cubic and quartic NURBS discretizations are compared against the isoparametric bilinear discretization introduced in [7]. The results show that the quadratic and cubic NURBS approximations exhibit notably slower convergence under uniform mesh refinement as the thickness decreases but the quartic approximation converges relatively quickly within the standard variational framework. The authors future work is concerned with building an isogeometric finite element method for modelling nonlinear structural response of thin-walled shells undergoing large rigid-body motions. The aim is to use the model in a aeroelastic framework for the simulation of flapping wings.

  2. Nitrogen-doped amorphous carbon-silicon core-shell structures for high-power supercapacitor electrodes.

    Science.gov (United States)

    Tali, S A Safiabadi; Soleimani-Amiri, S; Sanaee, Z; Mohajerzadeh, S

    2017-02-10

    We report successful deposition of nitrogen-doped amorphous carbon films to realize high-power core-shell supercapacitor electrodes. A catalyst-free method is proposed to deposit large-area stable, highly conformal and highly conductive nitrogen-doped amorphous carbon (a-C:N) films by means of a direct-current plasma enhanced chemical vapor deposition technique (DC-PECVD). This approach exploits C 2 H 2 and N 2 gases as the sources of carbon and nitrogen constituents and can be applied to various micro and nanostructures. Although as-deposited a-C:N films have a porous surface, their porosity can be significantly improved through a modification process consisting of Ni-assisted annealing and etching steps. The electrochemical analyses demonstrated the superior performance of the modified a-C:N as a supercapacitor active material, where specific capacitance densities as high as 42 F/g and 8.5 mF/cm 2 (45 F/cm 3 ) on silicon microrod arrays were achieved. Furthermore, this supercapacitor electrode showed less than 6% degradation of capacitance over 5000 cycles of a galvanostatic charge-discharge test. It also exhibited a relatively high energy density of 2.3 × 10 3  Wh/m 3 (8.3 × 10 6  J/m 3 ) and ultra-high power density of 2.6 × 10 8  W/m 3 which is among the highest reported values.

  3. Cenozoic stratigraphy and structure of the Chesapeake Bay region

    Science.gov (United States)

    Powars, David S.; Edwards, Lucy E.; Kidwell, Susan M.; Schindler, J. Stephen

    2015-01-01

    The Salisbury embayment is a broad tectonic downwarp that is filled by generally seaward-thickening, wedge-shaped deposits of the central Atlantic Coastal Plain. Our two-day field trip will take us to the western side of this embayment from the Fall Zone in Washington, D.C., to some of the bluffs along Aquia Creek and the Potomac River in Virginia, and then to the Calvert Cliffs on the western shore of the Chesapeake Bay. We will see fluvial-deltaic Cretaceous deposits of the Potomac Formation. We will then focus on Cenozoic marine deposits. Transgressive and highstand deposits are stacked upon each other with unconformities separating them; rarely are regressive or lowstand deposits preserved. The Paleocene and Eocene shallow shelf deposits consist of glauconitic, silty sands that contain varying amounts of marine shells. The Miocene shallow shelf deposits consist of diatomaceous silts and silty and shelly sands. The lithology, thickness, dip, preservation, and distribution of the succession of coastal plain sediments that were deposited in our field-trip area are, to a great extent, structurally controlled. Surficial and subsurface mapping using numerous continuous cores, auger holes, water-well data, and seismic surveys has documented some folds and numerous high-angle reverse and normal faults that offset Cretaceous and Cenozoic deposits. Many of these structures are rooted in early Mesozoic and/or Paleozoic NE-trending regional tectonic fault systems that underlie the Atlantic Coastal Plain. On Day 1, we will focus on two fault systems (stops 1–2; Stafford fault system and the Skinkers Neck–Brandywine fault system and their constituent fault zones and faults). We will then see (stops 3–5) a few of the remaining exposures of largely unlithified marine Paleocene and Eocene strata along the Virginia side of the Potomac River including the Paleocene-Eocene Thermal Maximum boundary clay. These exposures are capped by fluvial-estuarine Pleistocene terrace

  4. Caracterização físico-química e microestrutural de conchas de moluscos bivalves provenientes de cultivos da região litorânea da ilha de Santa Catarina Physical chemistry and micro structural characterization of shells of bivalve mollusks from sea farmer around the Santa Catarina island

    Directory of Open Access Journals (Sweden)

    Denyo Silva

    2010-01-01

    Full Text Available Samples of shells of oysters and mussels from sea farm around the Santa Catarina Island in south Brazil were collected and analyzed by DRX, FRX, SEM, CHN-S, FTIR, TG, AAS/Flame and AAS /GF. The results showed that the crystalline structure of mussel's shells is mainly formed by aragonite and the oyster's shells by calcite. The calcium percentage in both shells species was in the range of 33 to 35% and also 850 and 1200 mg/kg of strontium was detected in the shells of oysters and mussels, respectively. The content of organic matter was larger in the mussel's shells and the thermal degradation of both shells species occurred by three events at different temperatures from 250 to 830 ºC.

  5. TEOA-mediated formation of hollow core-shell structured CoNi2S4 nanospheres as a high-performance electrode material for supercapacitors

    Science.gov (United States)

    Liang, Jun; Li, Meng; Chai, Yao; Luo, Min; Li, Li

    2017-09-01

    In this study, we report for the first time a cost-effective and general approach for the high-yield synthesis of a hierarchical core-shell and hollow structure of ternary CoNi2S4 in a triethanolamine (TEOA)-assisted hydrothermal system. It is found that a continuous increase in TEOA usages facilitates the formation and transformation of hierarchical CoNi2S4 hollow nanospheres, and the formation mechanism of the unique structure is revealed to be assembly-then-inside-out evacuation and Ostwald ripening mechanism during the sulfidation process. More importantly, when used as faradaic electrode for supercapacitors, the hierarchical hollow CoNi2S4 nanospheres display not only exceptional pseudocapacitve performance with high specific capacitance (2035 Fg-1 at 1 Ag-1) and excellent rate capability (1215 Fg-1 at 20 Ag-1), but also superior cycling stability, with only about 8.7% loss over 3000 cycles at 10 Ag-1. This work can provide some guidance for us in the structural and compositional tuning of mixed binary-metal sulfides toward many desired applications.

  6. Core/Shell Structure of TiO2-Coated MWCNTs for Thermal Protection for High-Temperature Processing of Metal Matrix Composites

    Directory of Open Access Journals (Sweden)

    Laura Angélica Ardila Rodriguez

    2018-01-01

    Full Text Available The production of metal matrix composites with elevated mechanical properties depends largely on the reinforcing phase properties. Due to the poor oxidation resistance of multiwalled carbon nanotubes (MWCNTs as well as their high reactivity with molten metal, the processing conditions for the production of MWCNT-reinforced metal matrix composites may be an obstacle to their successful use as reinforcement. Coating MWCNTs with a ceramic material that acts as a thermal protection would be an alternative to improve oxidation stability. In this work, MWCNTs previously functionalized were coated with titanium dioxide (TiO2 layers of different thicknesses, producing a core-shell structure. Heat treatments at three different temperatures (500°C, 750°C, and 1000°C were performed on coated nanotubes in order to form a stable metal oxide structure. The MWCNT/TiO2 hybrids produced were evaluated in terms of thermal stability. Thermogravimetric analysis (TGA, X-ray diffraction (XRD, scanning electron microscopy (SEM, Fourier transform infrared spectroscopy (FTIR, Raman spectroscopy (RS, and X-ray photoelectron spectroscopy (XPS were performed in order to investigate TiO2-coated MWCNT structure and thermal stability under oxidative atmosphere. It was found that the thermal stability of the TiO2-coated MWCNTs was dependent of the TiO2 layer morphology that in turn depends on the heat treatment temperature.

  7. Ultrasonic assisted rapid synthesis of high uniform super-paramagnetic microspheres with core-shell structure and robust magneto-chromatic ability

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wenyan, E-mail: wiseyanyan@jit.edu.cn [College of Material Engineering, Jinling Institute of technology, Nanjing (China); Chen, Jiahua [College of Material Engineering, Jinling Institute of technology, Nanjing (China); Wang, Wei [Jiangsu Collaborative Innovation Center for Advanced Inorganic Function Composites, Nanjing Tech University, Nanjing (China); School of Physics and Optoelectronic Engineering, Nanjing University of Information Science & Technology, Nanjing (China); Lu, GongXuan [State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Science, Lanzhou 730000 (China); Hao, Lingyun [College of Material Engineering, Jinling Institute of technology, Nanjing (China); Ni, Yaru; Lu, Chunhua; Xu, Zhongzi [Jiangsu Collaborative Innovation Center for Advanced Inorganic Function Composites, Nanjing Tech University, Nanjing (China); State Key Laboratory of Materials-Oriented Chemical Engineering, College of Materials Science and Engineering, Nanjing Tech University, Nanjing (China)

    2017-03-15

    Super-paramagnetic core-shell microspheres were synthesized by ultrasonic assisted routine under low ultrasonic irradiation powers. Compared with conventional routine, ultrasonic effect could not only improve the uniformity of the core-shell structure of Fe{sub 3}O{sub 4}@SiO{sub 2}, but shorten the synthesis time in large scale.