WorldWideScience

Sample records for wedge-shaped shell structure

  1. 冰箱门内壳楔形冲孔模设计%Design of the Wedge-Shaped Piercing Die for the Inner Shell of the Refrigerator Door

    Institute of Scientific and Technical Information of China (English)

    秦建保

    2001-01-01

    分析了冰箱门内壳的冲孔工艺性,介绍了楔形冲孔模的结构及工作过程,还介绍了设计与工作中的注意事项。%The hole-piercing processing property of an inner shell of the refrigerator door was analyzed. The structure and the working process of the wedge-shaped piercing die were introduced.And the attention points in the design and manufacture of the die were stated.

  2. 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.

  3. Study on effect of segments erection tolerance and wedge-shaped segment on segment ring in shield tunnel

    Institute of Scientific and Technical Information of China (English)

    CHEN Jun-sheng; MO Hai-hong

    2006-01-01

    Deformation and dislocations of segments of shield tunnel in construction stage have apparent effect on tunnel structure stress and even cause local cracks and breakage in tunnel. 3D finite element method was used to analyze two segment ring models under uniform injected pressure: (1) segment ring without wedge-shaped segment, which has 16 types of preinstall erection tolerance; (2) segment ring with wedge-shaped segment, which has no preinstall erection tolerance. The analysis results indicate that different erection tolerances can cause irregular deformation in segment ring under uniform injected pressure, and that the tolerance values are enlarged further. Wedge-shaped segment apparently affects the overall deformation of segment ring without erection tolerances. The uniform injected pressure can cause deformation of ring with wedge-shaped segment irregular,and dislocations also appear in this situation. The stress of segment with erection tolerances is much larger than that of segment without erection tolerances. Enlarging the central angle of wedge-shaped segment can make the irregular deformation and dislocations of segments smaller. The analysis results also provide basis for erection tolerance control and improvement of segment constitution.

  4. Large scale test of wedge shaped micro strip gas counters

    Energy Technology Data Exchange (ETDEWEB)

    Ackermann, M.; Atz, S.; Aulchenko, V.; Bachmann, S.; Baiboussinov, B.; Barthe, S.; Beaumont, W.; Beckers, T.; Beissel, F.; Benhammou, Y.; Bergdolt, A.M.; Bernier, K.; Bluem, P.; Bondar, A.; Bouhali, O.; Boulogne, I.; Bozzo, M.; Brom, J.M.; Camps, C.; Chorowicz, V.; Coffin, J.; Commichau, V.; Contardo, D.; Croix, J.; Troy, J. de; Drouhin, F.; Eberle, H.; Fluegge, G.; Fontaine, J.-C.; Geist, W.; Goerlach, U.; Gundlfinger, K.; Hangarter, K.; Haroutunian, R.; Helleboid, J.M.; Henkes, Th.; Hoffer, M.; Hoffman, C.; Huss, D.; Ischebeck, R.; Jeanneau, F.; Juillot, P.; Junghans, S.; Kapp, M.R.; Kaercher, K.; Knoblauch, D.; Kraeber, M.; Krauth, M.; Kremp, J.; Lounis, A.; Luebelsmeyer, K.; Maazouzi, C.; Macke, D.; Metri, R.; Mirabito, L.; Mueller, Th.; Nagaslaev, V.; Neuberger, D.; Nowack, A.; Pallares, A.; Pandoulas, D.; Petertill, M.; Pooth, O.; Racca, C.; Ripp, I.; Ruoff, E.; Sauer, A.; Schmitz, P.; Schulte, R.; Schultz von Dratzig, A.; Schunk, J.P.; Schuster, G.; Schwaller, B.; Shektman, L.; Siedling, R.; Sigward, M.H.; Simonis, H.J.; Smadja, G.; Stefanescu, J.; Szczesny, H.; Tatarinov, A.; Thuemmel, W.H.; Tissot, S.; Titov, V.; Todorov, T.; Tonutti, M.; Udo, F.; Velde, C. Vander. E-mail: vandervelde@hep.iihe.ac.be; Doninck, W. van; Dyck, Ch. van; Vanlaer, P.; Lancker, L. van; Verdini, P.G.; Weseler, S.; Wittmer, B.; Wortmann, R.; Zghiche, A.; Zhukov, V

    1999-11-01

    In order to check the system aspects of the forward-backward MSGC tracker designed for the future CMS experiment at LHC, 38 trapezoidal MSGC counters assembled in six multi-substrates detector modules were built and exposed to a muon beam at the CERN SPS. Results on the gain uniformity along the wedge-shaped strip pattern and across the detector modules are shown together with measurements of the detection efficiency and the spatial resolution.

  5. Large scale test of wedge shaped micro strip gas counters

    CERN Document Server

    Ackermann, M; Aulchenko, V M; Bachmann, S; Baibusinov, B O; Barthe, S; Beaumont, W; Beckers, T; Beissel, F; Benhammou, Ya; Bergdolt, A M; Bernier, K; Blüm, H P; Bondar, A E; Bouhali, O; Boulogne, I; Bozzo, M; Brom, J M; Camps, C; Chorowicz, V; Coffin, J P; Commichau, V; Contardo, D; Croix, J; De Troy, J G; Drouhin, F; Eberle, H; Flügge, G; Fontaine, J C; Geist, Walter M; Goerlach, U; Gundlfinger, K; Hangarter, K; Haroutunian, R; Helleboid, J M; Henkes, T; Hoffer, M; Hoffmann, C; Huss, D; Ischebeck, R; Jeanneau, F; Juillot, P; Junghans, S; Kapp, M R; Kärcher, K; Knoblauch, D; Kräber, M H; Krauth, M; Kremp, J; Lounis, A; Lübelsmeyer, K; Maazouzi, C; Macke, D; Metri, R; Mirabito, L; Müller, T; Nagaslaev, V; Neuberger, D; Nowak, A; Pallarès, A; Pandoulas, D; Petertill, M; Pooth, O; Racca, C; Ripp, I; Ruoff, E; Sauer, A; Schmitz, P; Schulte, R; Schultz von Dratzig, A; Schunk, J P; Schuster, G; Schwaller, B; Shekhtman, L I; Siedling, R; Sigward, M H; Simonis, H J; Smadja, G; Stefanescu, J; Szczesny, H; Tatarinov, A A; Thümmel, W H; Tissot, S; Titov, V; Todorov, T; Tonutti, M; Udo, Fred; Van der Velde, C; Van Doninck, W K; Van Dyck, C; Vanlaer, P; Van Lancker, L; Verdini, P G; Weseler, S; Wittmer, B; Wortmann, R; Zghiche, A; Zhukov, V

    1999-01-01

    In order to check the system aspects of the forward-backward MSGC tracker designed for the future CMS experiment at LHC, 38 trapezoidal MSGC counters assembled in six multi-substrates detector modules were built and exposed to a muon beam at the CERN SPS. Results on the gain uniformity along the wedge-shaped strip pattern and across the detector modules are shown together with measurements of the detection efficiency and the spatial resolution. (8 refs).

  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. Enhancement of linear and second-order hyperpolarizabilities in wedge-shaped nanostructures

    Science.gov (United States)

    Jayabalan, J.; Singh, Manoranjan P.; Rustagi, K. C.

    2003-08-01

    Analytical solutions for the wave functions for free electrons inside a wedge-shaped quantum dot are reported. For silver wedge-shaped quantum dots, linear and second-order hyperpolarizabilities are calculated for various apex angles. It is found that linear and nonlinear hyperpolarizabilities both increase with decreasing apex angle.

  8. Modal Analysis in Lined Wedge-Shaped Ducts

    Science.gov (United States)

    Mechel, F. P.

    1998-10-01

    It has been suggested to describe the sound field in a wedge-shaped duct in a cylindrical co-ordinate system in which the boundaries of the wedge lie in a co-ordinate surface. This suggestion was developed in a companion paper [1]. The wave equation can be separated only if the boundaries are ideally reflecting (rigid or soft). Two solutions were proposed in reference [1] for absorbing boundaries. In the first solution the sound field is composed of “ideal modes” (modes in a wedge with ideally reflecting boundaries); the boundary condition at the absorbing boundary then leads to a system of equations for the mode amplitudes. The problem with this method lies in the fact that there is no radial orthogonality of the ideal modes so that the precision of the field synthesis by ideal modes is doubtful. In the second method in reference [1] one defines “fictitious modes” which satisfy the boundary conditions at the flanks exactly and which are based on hypergeometric functions as radial functions, but which produce a “rest” in the wave equation. It was described how this rest can be minimized; this procedure leads to slow numerical integrations. In the present paper, the wedge is subdivided into duct sections with parallel walls (the boundary is stepped); the fields in the sections are composed of duct modes (modes in a straight lined duct); the mode amplitudes are determined from the boundary conditions at the section limits. The advantages of the present method are (analytically) the duct modes are orthogonal across the sections, so the mode amplitudes can be determined with the usual precision of a modal analysis, and (numerically) no numerical integrations are needed.

  9. 塔里木盆地巴楚隆起北缘阿恰基底卷入构造%Basement-Involved wedge-shaped Structure of Aqia Fault in Northern Magin of Bachu Uplift in Northwestern Tarim Basin, Northwest China

    Institute of Scientific and Technical Information of China (English)

    杨庚; 李本亮; 杨海军; 陈竹新; 王晓波; 张朝军; 雷永良

    2012-01-01

    The Tarim Basin records the history of deposition and deformation affected by the Indian-Eurasia collision during the Cenozoic. The seismic data shows that the faulted rigid Bachu uplift, central Tarim, is a paleo-uplift covered by Quaternary deposits. NW-striking Aqia fault, Qiaolaitnaiti fault and Salambulake syncline and anticline between them were developed on the north margin of the Bachu uplift, northward adjacent to Awati depression. Many seismic lines and well data show that the Aqia fault is a deep basement-involved, south-dipping thrust fault, and the shallow structures are both Qiaolaimaiti north-dipping thrust fault and Salambulake fold. The Aqia fault cuts through the Precambrian basement to the Middle Cambrian evaporates and its displacements decrease from west to east. Salambulake anticline is a fault-propagation fold controlled by the Qiaolaimaiti fault which develops from the main decollement layer of the Cambrian evaporates. The south-dipping basement-involved fault, north-dipping cover-detached fault and Salambulake anticline forms a typical wedge-shaped structure in profile and a triangular structural belt in map view. The Aqia fault and the Salambulake fold extend northwestwardly into the Kelpin thrust belt and forms the NW-striking surface structures superimposed by northeastern-striking deformation. The growth strata indicates that NW-striking wedge-shaped structure formed during Eocene to Miocene, which extends northwestwards into the Kelping thrust zone formed in the Quaternary.%塔里木盆地巴楚隆起为第四系不整合覆盖的古隆起,在其西北缘发育NW走向的阿恰断裂、萨拉姆布拉克背斜、向斜和隐伏的乔来麦提断裂.地震剖面和钻井资料显示,阿恰断裂为倾向南的基底卷入逆冲断裂,向北逆冲,错断层位从前寒武系基底一直到中寒武统膏岩,从西向东逆冲断距减少.乔来麦提断裂则以中寒武统膏岩为滑动面,向南逆冲,并在断层端部发育萨拉

  10. Statics of Magnetic Fluid Drop with Compound Magnetic Core in a Wedge-Shaped Channel

    Directory of Open Access Journals (Sweden)

    V. Bashtovoi

    2013-12-01

    Full Text Available A behavior of magnetic fluid drop with compound magnetic core in a wedge-shaped channel was studied experimentally. The study examines influence of magnetic fluid properties, its volume and magnetic field on statics of the system compound magnet – magnetic fluid drop in wedge-shaped channel. The possibility to change the static conditions of such system by altering magnetic field of the core was observed

  11. 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...

  12. RESEARCH ON THE MOTION CHARACTERISTICS OF FIBER SUSPENSIONS IN A WEDGE-SHAPED FLOW

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In this paper the motion of cylindrical particles in a wedge-shaped flow was studied. The velocity distribution of wedge-shaped flow was simulated first, then the Euler-Lagrange model used to calculate the motion of cylindrical particles. The evolution of particle location, velocity and orientation with time was examined. The trajectories of the particles with different particle Stokes number, rate of flow and initial particle orientation were drawn. The results indicate that the Stokes number and initial orientation are important parameters which affect the particle motion. The conclusions are helpful to the engineering applications.

  13. 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....

  14. Plate shell structures of glass

    DEFF Research Database (Denmark)

    Bagger, Anne

    . This modelling technique is used to model a plate shell structure with a span of 11.5 meters in the FE software \\textsc{Abaqus}. The structure is analyzed with six different connection details with varying stiffness characteristics, to investigate the influence of these characteristics on the structural effects...... University, a script has been developed for an automated generation of a given plate shell geometry and a corresponding finite element (FE) model. A suitable FE modelling technique is proposed, suggesting a relatively simple method of modelling the connection detail's stiffness characteristics....... Based on these investigations, and FE analysis of other plate shell models, the structural behaviour is described. Possible methods of estimating the stresses in a given plate shell structure are proposed. The non-linear behaviour of a plate shell structure is investigated for varying parameters...

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

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jeong Hun; Park, Goon Cherl; Cho, Hyoung Kyu [Seoul National University, Seoul (Korea, Republic of); Yoon, Su Jong [Idaho National Laboratory, Idaho Falls (United States)

    2014-10-15

    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

  16. Direct Preparation of Nano-Quasicrystals via a Water-Cooled Wedge-Shaped Copper Mould

    Directory of Open Access Journals (Sweden)

    Zhifeng Wang

    2012-01-01

    Full Text Available We have successfully synthesized multicomponent Mg-based nano-quasicrystals (nano-QCs through a simple route by using a water-cooled wedge-shaped copper mould. Nanoscale QCs are prepared directly on tip of wedge-shaped castings. The further study shows that nano-QCs in the Mg71Zn26Y2Cu1 alloy show well microhardness of greater than HV450. Electrochemical properties of three kinds of quasicrystal alloys are investigated in simulated seawater. The Mg71Zn26Y2Cu1 nano-QC alloy presents the best corrosion resistance in this study for the formation of well-distributed nano-QC phases (1~5 nm and polygonal Mg2(Cu,Y nanophases (40~50 nm.

  17. Large negative Goos-H(a)nchen shift from a wedge-shaped thin film

    Institute of Scientific and Technical Information of China (English)

    Jianping Bai; Yaoju Zhang

    2009-01-01

    The analytical expression for the complex amplitude of light reflected from a wedge-shaped thin film is derived.For plane wave incidence,a simple ray tracing approach is used to calculate Goos-H(a)nchen(GH)shifts;and for non-plane wave incidence,for example,a Gaussian beam,the angular spectrum approach of plane wave is used in simulation.The two approaches predict that a wedge-shaped thin film can produce large negative longitudinal GH shifts.Although the reflectivity is small near the condition of resonance,the large negative GH shifts can be more easily detected in comparison with the shift from a plane-paxallel film in vacuum.

  18. 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.

  19. CALCULATION OF DISPLACEMENT FIELD AND DEFORMATIONS OF WEDGE SHAPED TWIN WITH THE HELP OF MESOSCOPIC DISLOCATIONAL MODEL

    Directory of Open Access Journals (Sweden)

    Y. V. Vasilevich

    2011-01-01

    Full Text Available Displacements and deformations of a wedge-shaped twin have been calculated with the help of mesoscopic dislocational model. It has been shown that deformations are localized at twin boundaries and twin top and also at some limited areas which are rather far from the twin. 

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

    CERN Document Server

    Yagisawa, Yui; 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 dynamics, bubbling and cavity regimes. 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 consid...

  1. A computational study of supersonic combustion behind a wedge-shaped flameholder

    Science.gov (United States)

    Fureby, C.; Fedina, E.; Tegnér, J.

    2014-01-01

    In this study, large eddy simulation (LES) has been used to examine supersonic flow, mixing, self-ignition and combustion in a model scramjet combustor and has been compared against the experimental data. The LES model is based on an unstructured finite-volume discretization, using monotonicity-preserving flux reconstruction of the filtered mass, momentum, species and energy equations. Both a two-step and a seven-step hydrogen-air mechanism are used to describe the chemical reactions. Additional comparisons are made with results from a previously presented flamelet model. The subgrid flow terms are modeled using a mixed model, whereas the subgrid turbulence-chemistry interaction terms are modeled using the partially stirred reactor model. Simulations are carried out on a scramjet model experimentally studied at Deutsches Zentrum für Luft- und Raumfahrt consisting of a one-sided divergent channel with a wedge-shaped flame holder at the base of which hydrogen is injected. The LES predictions are compared with experimental data for velocity, temperature, wall pressure at different cross sections as well as schlieren images, showing good agreement for both first- and second-order statistics. In addition, the LES results are used to illustrate and explain the intrinsic flow, and mixing and combustion features of this combustor.

  2. Analytical expression for the sheath edge around wedge-shaped cathodes

    Science.gov (United States)

    Sheridan, T. E.

    2008-03-01

    The sheath is the boundary layer separating a quasi-neutral plasma from a material electrode. Understanding the sheath is important for numerous applications, including plasma-based ion implantation, plasma etching of semiconductors, plasma assisted electrostatic cleaning, and Langmuir probes. In a 1D planar geometry, the Child-Langmuir (CL) law describes the sheath when the bias on a negative electrode, i.e., a cathode, is much greater than the electron temperature. In this case, the sheath width s is an eigenvalue of the problem. In 2D, the sheath edge is an unknown line (an ``eigen-boundary") which is determined by a set of coupled, nonlinear, partial differential equations. I have found an expression for the sheath edge around a 2D wedge-shaped cathode with included angle θw. In polar coordinates (r,θ), the sheath edge is a solution of r(aθ)=as where s is the planar sheath width far from the corner and θw=2π- π/a, so that a=1/2 gives a knife edge, while a=2/3 gives a square corner. This result is verified by comparison with the numerical solutions of Watterson [P. A. Watterson, J. Phys. D 22, 1300 (1989)].

  3. Experimental study of slot jet impingement heat transfer on a wedge-shaped surface

    Science.gov (United States)

    Rahimi, Mostafa; Irani, Mohammad

    2012-12-01

    An experimental investigation was conducted to study the convective heat transfer rate from a wedge-shaped surface to a rectangular subsonic air jet impinging onto the apex of the wedge. The jet Reynolds number, nozzle-to-surface distance and the wedge angle were considered as the main parameters. Jet Reynolds number was ranged from 5,000 to 20,000 and two dimensionless nozzle-to-surface distances h/w = 4 and 10 were examined. The apex angle of the wedge ranged from 30° to 180° where the latter case corresponds with that of a flat surface. Velocity profile and turbulence intensity were provided for free jet flow using hot wire anemometer. Local and average Nusselt numbers on the impinged surface are presented for all the configurations. Based on the results presented, the local Nusselt number at the stagnation region increases as the wedge angle is decreased but, it then decreases over the remaining area of the impinged surface. Average Nusselt number over the whole surface is maximum when the wedge angle is 180° (i.e. plane surface) for any jet and nozzle-to-surface configuration.

  4. Groundwater response to tidal fluctuations in wedge-shaped confined aquifers

    Science.gov (United States)

    Cuello, Julián E.; Guarracino, Luis; Monachesi, Leonardo B.

    2017-08-01

    Most of the analytical solutions to describe tide-induced head fluctuations assume that the coastal aquifer has a constant thickness. These solutions have been applied in many practical problems ignoring possible changes in aquifer thickness, which may lead to wrong estimates of the hydraulic parameters. In this study, a new analytical solution to describe tide-induced head fluctuations in a wedge-shaped coastal aquifer is presented. The proposed model assumes that the aquifer thickness decreases with the distance from the coastline. A closed-form analytical solution is obtained by solving a boundary-value problem with both a separation of variables method and a change of variables method. The analytical solution indicates that wedging significantly enhances the amplitude of the induced heads in the aquifer. However, the effect on time lag is almost negligible, particularly near the coast. The slope factor, which quantifies the degree of heterogeneity of the aquifer, is obtained and analyzed for a number of hypothetical scenarios. The slope factor provides a simple criterion to detect a possible wedging of the coastal aquifer.

  5. Computational analysis of responses of a wedge-shaped-tip optical fiber probe in bubble measurement.

    Science.gov (United States)

    Sakamoto, A; Saito, T

    2012-07-01

    Optical-fiber probing is widely employed in bubble/droplet measurement in gas-liquid two-phase flows. Several types of optical fiber probes with a very high S/N ratio and high performance have been developed, but further improvement in the probes' measurement accuracy and reliability for industrial applications is desired. We tried to eliminate optical noise in the probe measurements, and we found that the signals include some peak signs that have potential for advanced measurement with optical-fiber probing. We developed a ray-tracing numerical simulator and identified the mechanisms underlying the generation of the signals. In order to numerically simulate the optical probing signals, the simulator must use 3D frameworks composed of incident beams, the reflection and refraction on the surfaces of the optical elements (i.e., an optical fiber, a sensing tip, an air phase, and a water phase), and beams returning from the sensing tip to the other tip through the fiber. We used all of these in a simple rendering framework based on a ray-tracing algorithm with Fresnel's law, and we observed the mechanism of some promising signals that may be useful for extracting the hidden potential of optical-fiber probing. To verify the simulator's performance, we carried out three comparative experiments with fundamental setups using a wedge-shaped single-tip optical fiber probe, examining: (1) the beam trajectories and energy leaking out from the sensing tip into the surrounding air phase or water phase, (2) the probing signals throughout penetration of the sensing tip at the air-water free interface in light of the three-dimensional deformation, and (3) the probing signals throughout penetration of the sensing tip into a bubble in light of the three-dimensional bubble shape. As a result, (a) we found that an optical fiber probe with a wedge-shaped tip has particular characteristics of beam emissions from the tip, and the emitting angles switched depending on the phases covering

  6. Engineered Magnetic Core-Shell Structures.

    Science.gov (United States)

    Alavi Nikje, Mir Mohammad; Vakili, Maryam

    2015-01-01

    In recent years, engineered magnetic core-shell structures are playing an important role in the wide range of various applications. These magnetic core-shell structures have attracted considerable attention because of their unique properties and various applications. Also, the synthesis of engineered magnetic core-shell structures has attracted practical interest because of potential applications in areas such as ferrofluids, medical imaging, drug targeting and delivery, cancer therapy, separations, and catalysis. So far a large number of engineered magnetic core-shell structures have been successfully synthesized. This review article focuses on the recent progress in synthesis and characterization of engineered magnetic core-shell structures. Also, this review gives a brief description of the various application of these structures. It is hoped that this review will play some small part in helping future developments in important field.

  7. The structural acoustic properties of stiffened shells

    DEFF Research Database (Denmark)

    Luan, Yu

    2008-01-01

    . This is important when a number of stiffened plates are combined in a complicated structure composed of many plates. However, whereas the equivalent plate theory is well established there is no similar established theory for stiffened shells. This paper investigates the mechanical and structural acoustic properties...... of curved shells with stiffening ribs. Finite element simulations and experimental data will be compared and discussed....

  8. 楔状缺损临床研究进展%Clinical research progress of wedge shaped defects

    Institute of Scientific and Technical Information of China (English)

    韦界飞

    2012-01-01

    Wedge shaped defects is common non-caries dental disease, which caused by chronic consumption of hard tissue close to lips, huccal and neck. The defects formed by the intersection of two planes, with neatly edge, hard and smooth surface; the defects general had the same color of dental hard tissue, but sometimes could also be with other different colors; the defects were commonly found in the premolars, especially in the first premolar; wedge-shaped defect increase with age growth. In recent years, there were more and more studies focusing on the etiology and clinical progress. Here, we summarized the risk factors, prevalence and clinical treatment for wedge shaped defects.%楔状缺损是非龋性疾病中的常见病,是牙齿唇、颊面牙颈部硬组织发生慢性消耗所致的缺损.其缺损由两个平面相交而成,边缘整齐,表面坚硬光滑,一般均为牙体硬组织本色,有时可有不同程度的着色,好发生于前磨牙,尤其是第一前磨牙,随着年龄增长,楔状缺损有增加的趋势,年龄愈大,楔状缺损愈严重.近年来国内外学者对于楔状缺损的病因学研究更加深入、临床治疗进展的报道也越来越多,本文对楔状缺损的病因、流行情况及治疗进展进行综述.

  9. Foraminiferal shell structures: exoskeleton and endoskeleton

    Directory of Open Access Journals (Sweden)

    Lukas Hottinger

    2006-04-01

    Full Text Available Larger foraminiferal shell structures are illustrated and described in terms of exoskeleton and endoskeleton. Several examples are reported. The paper is organized as a large poster that can be displayed in laboratory and class rooms.

  10. 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...

  11. Deterministic Spin-Orbit Torque Switching of a Perpendicularly Polarized Magnet Using Wedge Shape of the Magnet

    Science.gov (United States)

    Bhowmik, Debanjan; Salahuddin, Sayeef

    2016-10-01

    Spin-orbit torque provides an efficient way to switch magnets for low power memory applications by reducing the current density needed to switch the magnetization. Perpendicularly polarized magnets are preferred for high density data storage applications because of their high thermal stability in scaled dimensions. However, spin-orbit torque cannot switch a perpendicularly polarized magnet deterministically from up to down and down to up in the absence of an external magnetic field because spin-orbit torque alone cannot break the symmetry of the system. This poses a severe challenge to the applicability of spin-orbit torque for memory devices. In this paper, we show through micromagnetic simulations that when spin-orbit torque is applied on a magnet with a wedge shape, the moments of the magnet are aligned in-plane. On removal of the spin-orbit torque the moments deterministically evolve to vertically upward or downward direction because the anisotropy axis of the magnet is tilted away from the vertical direction owing to the wedge shape of the magnet. Thus, spin-orbit torque driven deterministic switching of the magnet in the absence of an external magnetic field is possible.

  12. The New Wedge-Shaped Hubble Diagram of 398 SCP Supernovae According to the Expansion Center Model

    CERN Document Server

    Lorenzi, Luciano

    2010-01-01

    Following the successful dipole test on 53 SCP SNe Ia presented at SAIt2004 in Milan, this 9th contribution to the ECM series beginning in 1999 in Naples (43th SAIt meeting: "Revolutions in Astronomy") deals with the construction of the new wedge-shaped Hubble diagram obtained with 398 supernovae of the SCP Union Compilation (Kowalski et al. 2008) by applying a calculated correlation between SNe Ia absolute blue magnitude MB and central redshift z0, according to the expansion center model. The ECM distance D of the Hubble diagram (cz versus D) is computed as the ratio between the luminosity distance DL and 1 + z. Mathematically D results to be a power series of the light-space r run inside the expanding cosmic medium or Hubble flow; thus its expression is independent of the corresponding z. In addition one can have D = D(z, h) from the ECM Hubble law by using the h convention with an anisotropic HX. It is proposed to the meeting that the wedge-shape of this new Hubble diagram be confirmed independently as mai...

  13. Shell structure of nuclei far from stability

    CERN Document Server

    Grawe, H

    2001-01-01

    The experimental status of shell structure studies in medium-heavy nuclei far off the line of beta-stability is reviewed. Experimental techniques, signatures for shell closure and expectations for future investigations are discussed for the key regions around sup 4 sup 8 sup , sup 5 sup 6 Ni, sup 1 sup 0 sup 0 Sn for proton rich nuclei and the neutron-rich N=20 isotones, Ca, Ni and Sn isotopes.

  14. UHPFRC in large span shell structures

    NARCIS (Netherlands)

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

    2013-01-01

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

  15. Shape-changing shell-like structures.

    Science.gov (United States)

    Pagitz, M; Bold, J

    2013-03-01

    Plants such as Dionaea muscipula (Venus Flytrap) can change the shape of their shell-like leaves by actively altering the cell pressures. These leaves are hydraulic actuators that do not require any complex controls and that possess an energy efficiency that is unmatched by natural or artificial muscles (Huber et al 1997 Proc. R. Soc. A 453 2185-205). We extend our previous work (Pagitz et al 2012 Bioinspir. Biomim. 7 016007) on pressure-actuated cellular structures by introducing a concept for shape-changing shell-like structures that can significantly alter their Gaussian curvature. The potential of this concept is demonstrated by a hemispherical shell that can reversibly change the sign of its Gaussian curvature. Furthermore, it is shown that a snap-through behaviour, similar to the one known from Dionaea muscipula, can be achieved by lowering the pressure in a single layer of cells.

  16. Energy constancy checking for electron beams using a wedge-shaped solid phantom combined with a beam profile scanner

    Energy Technology Data Exchange (ETDEWEB)

    Rosenow, U.F.; Islam, M.K.; Gaballa, H.; Rashid, H. (Univ. of Goettingen (Germany, F.R.))

    1991-01-01

    An energy constancy checking method is presented which involves a specially designed wedge-shaped solid phantom in combination with a multiple channel ionization chamber array known as the Thebes device. Once the phantom/beam scanner combination is set up, measurements for all electron energies can be made and evaluated without re-entering the treatment room. This is also valid for the readjustment of beam energies which are found to deviate from required settings. The immediate presentation of the measurements is in the form of crossplots which resemble depth dose profiles. The evaluation of the measured data can be performed using a hand-held calculator, but processing of the measured signals through a PC-type computer is advisable. The method is insensitive to usual fluctuations in beam flatness. The sensitivity and reproducibility of the method are more than adequate. The method may also be used in modified form for photon beams.

  17. Energy constancy checking for electron beams using a wedge-shaped solid phantom combined with a beam profile scanner.

    Science.gov (United States)

    Rosenow, U F; Islam, M K; Gaballa, H; Rashid, H

    1991-01-01

    An energy constancy checking method is presented which involves a specially designed wedge-shaped solid phantom in combination with a multiple channel ionization chamber array known as the Thebes device. Once the phantom/beam scanner combination is set up, measurements for all electron energies can be made and evaluated without re-entering the treatment room. This is also valid for the readjustment of beam energies which are found to deviate from required settings. The immediate presentation of the measurements is in the form of crossplots which resemble depth dose profiles. The evaluation of the measured data can be performed using a hand-held calculator, but processing of the measured signals through a PC-type computer is advisable. The method is insensitive to usual fluctuations in beam flatness. The sensitivity and reproducibility of the method are more than adequate. The method may also be used in modified form for photon beams.

  18. Anti-plane deformations around arbitrary-shaped canyons on a wedge-shape half-space: moment method solutions

    Institute of Scientific and Technical Information of China (English)

    Nazaret Dermendjian; Vincent W. Lee; Jianwen Liang(梁建文)

    2003-01-01

    The wave propagation behavior in an elastic wedge-shaped medium with an arbitrary shaped cylindrical canyon at its vertex has been studied. Nunerical computation of the wave displacement field is carried out on and near the canyon surfaces using weighted-residuals (moment method). The wave displacement fields are computed by the residual mcthod for the cases of elliptic, circular, rounded-rectangular and flat-elliptic canyons. The analysis demonstrates that thc resulting surface displacemcnt depends, as in similar previous analyses, on several factors including, but not limited, to the angle of thc wedge, thc geometry of thc vertex, the frcquencies of thc incident waves, the angles of incidence, and the material properties of the media. The analysis provides intriguing results that help to explain geophysical observations regarding the amplification of seismic energy as a function of site conditions.

  19. Numerical Studies on the Performance of Scramjet Combustor with Alternating Wedge-Shaped Strut Injector

    Science.gov (United States)

    Choubey, Gautam; Pandey, K. M.

    2017-04-01

    Numerical analysis of the supersonic combustion and flow structure through a scramjet engine at Mach 7 with alternating wedge fuel injection and with three angle of attack (α=-3°, α=0°, α=3°) have been studied in the present research article. The configuration used here is slight modification of the Rabadan et al. scramjet model. Steady two dimensional (2D) Reynolds-averaged Navier-Stokes (RANS) simulation and Shear stress transport (SST) based on k-ω turbulent model is used to predict the shock structure and combustion phenomenon inside the scramjet combustor. All the simulations are done by using Ansys 14-Fluent code. The combustion model used here is the combination of eddy dissipation and finite rate chemistry models since this model avoids Arrhenius calculations in which reaction rates are controlled by turbulence. Present results show that the geometry with negative angle of attack (α=-3°) have lowest ignition delay and it improves the performance of scramjet combustor as compared to geometry with α=0°, α=3°. The combustion phenomena and efficiency is also found to be stronger and highest in case of α=-3°.

  20. Plate shell structures - statics and stability

    DEFF Research Database (Denmark)

    Almegaard, Henrik

    2008-01-01

    This paper describes the basic structural system, statics and spatial stability of plate shells. The structural system can be considered as a single layer of planar elements, where each element only transfers in-plane (membrane) forces to its neighbouring elements. External out-of-plane loads...... are carried into the structure as in-plane forces by plate action in each element. These in-plane forces are then carried through the plate structure to the supports as in-plane forces by membrane action. The consequence is that the spatial stability of the structure can be simply analysed by considering...... the plate system as only subject to in-plane loads. The stability of such systems is based on the fact that each plane element is held fixed in space by three fixed support lines and that these support lines can be provided by three plane neighbour elements. This means that the spatial stability of a plate...

  1. Synthesis of core-shell structured magnetic nanoparticles with a carbide shell

    Science.gov (United States)

    Hou, Shushan; Chi, Yue; Zhao, Zhankui

    2017-03-01

    Core-shell structured materials combining the functionalities of the core and shell have great application potential in many fields. In this work, by combining solvothermal, polymerization and the high temperature carbonization, we have successfully developed a facile method to generate core-shell structured nanoparticles which possess an internal magnetic nanoparticle with a carbide shell. The thickness of resorcinol formaldehyde resin as intermediate transition shell could be easily adjusted by changing the concentration of the RF precursor. The resulting nanoparticles possess well-defined structure, uniform size and high magnetization. The unique nanostructure of the magnetic core-shell structured nanoparticles could lead to many promising applications in areas ranging from drug delivery to the purifyication of sewage.

  2. Evaluation of Four Different Restorative Materials for Restoration of the Periodontal Condition of Wedge-Shaped Defect: A Comparative Study.

    Science.gov (United States)

    Ruan, Jian-Yong; Gong, Zheng-Lin; Zhang, Rui-Zhi; Zhang, Zhe; Xu, Ran; Li, Da-Xu; Ren, Le; Tao, Hong

    2017-09-16

    BACKGROUND This study aimed to conduct a clinical evaluation of four restorative materials for restoration of dental wedge-shaped defect (WSD) and their impacts on periodontal tissues. MATERIAL AND METHODS A total of 280 maxillary premolars with dental WSD were selected from 106 patients; the patient cases were divided into eight groups according to different combinations of restorative materials (flowable resin composites, Dyract compomers, glass ionomer cement (GIC), light-curing composite resin), and WSD positions (approaching gingival and subgingival positions). Gingival crevicular fluid (GCF) volume, levels of aspartate aminotransferase (AST), alkaline phosphatase (ALP), and interleukin-1β (IL-1β) in GCF were analyzed, while probing depth (PD), plaque index (PLI), and sulcus bleeding index (SBI) were also measured. The periodontal conditions of all patients were followed prior to restoration, as well as six months and 12 months after restoration. RESULTS After six months of restoration, the overall clinical success rates of flowable resin composites, Dyract compomers, and light-curing composite resin were greater than those of GIC. GCF volume, GCF-AST, IL-1β levels, PD, PLI, and SBI of cases restored by GIC were higher than those restored by the other three materials. After 12 months of restoration, the overall clinical success rates of flowable resin composites and Dyract compomers were greater than those of light-curing composite resin and GIC. GCF volume, GCF-AST, GCF-ALP, IL-1β levels, PD, PLI, and SBI of cases restored by GIC were higher than those restored by the other three materials. CONCLUSIONS Our study provided evidence that the clinical efficacy of flowable resin composites, Dyract compomers, and light-curing composite resin was greater than that of GIC for restoration of dental WSD.

  3. 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...... requirements in the three phases of the design process; sketching, evaluation and modification. The engineering analysis is not a time consuming process, as they are at a conceptual level corresponding to the design stage. By this approach the aesthetic, functional and technical requirement are developed...... together through a process of several iterations that includes sketching, evaluation and modification. Based on this procedure a design model is proposed as a generative design model relating the engineering profession and architectural profession as a design model for conceptual architectural design....

  4. Dynamic structure of active nematic shells

    Science.gov (United States)

    Zhang, Rui; Zhou, Ye; Rahimi, Mohammad; de Pablo, Juan J.

    2016-11-01

    When a thin film of active, nematic microtubules and kinesin motor clusters is confined on the surface of a vesicle, four +1/2 topological defects oscillate in a periodic manner between tetrahedral and planar arrangements. Here a theoretical description of nematics, coupled to the relevant hydrodynamic equations, is presented here to explain the dynamics of active nematic shells. In extensile microtubule systems, the defects repel each other due to elasticity, and their collective motion leads to closed trajectories along the edges of a cube. That motion is accompanied by oscillations of their velocities, and the emergence and annihilation of vortices. When the activity increases, the system enters a chaotic regime. In contrast, for contractile systems, which are representative of some bacterial suspensions, a hitherto unknown static structure is predicted, where pairs of defects attract each other and flows arise spontaneously.

  5. Conceptual Design Tool for Concrete Shell Structures

    DEFF Research Database (Denmark)

    Holst, Malene Kirstine; Kirkegaard, Poul Henning

    2011-01-01

    requirements in the three phases of the design process; sketching, evaluation and modification. The engineering analysis is not a time consuming process, as they are at a conceptual level corresponding to the design stage. By this approach the aesthetic, functional and technical requirement are developed...... together through a process of several iterations that includes sketching, evaluation and modification. Based on this procedure a design model is proposed as a generative design model relating the engineering profession and architectural profession as a design model for conceptual architectural design.......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...

  6. Design optimization of a torpedo shell structure

    Institute of Scientific and Technical Information of China (English)

    YU De-hai; SONG Bao-wei; LI Jia-wang; YANG Shi-xing

    2008-01-01

    An optimized methodology to design a more robust torpedo shell is proposed. The method has taken into account reliability requirements and controllable and uncontrollable factors such as geometry, load, material properties, manufacturing processes, installation, etc. as well as human and environmental factors. The result is a more realistic shell design. Our reliability optimization design model was developed based on sensitivity analysis. Details of the design model are given in this paper. An example of a torpedo shell design based on this model is given and demonstrates that the method produces designs that are more effective and reliable than traditional torpedo shell designs. This method can be used for other torpedo system designs.

  7. Material with core-shell structure

    Science.gov (United States)

    Luhrs, Claudia; Richard, Monique N.; Dehne, Aaron; Phillips, Jonathan; Stamm, Kimber L.; Fanson, Paul T.

    2011-11-15

    Disclosed is a material having a composite particle, the composite particle including an outer shell and a core. The core is made from a lithium alloying material and the outer shell has an inner volume that is greater in size than the core of the lithium alloying material. In some instances, the outer mean diameter of the outer shell is less than 500 nanometers and the core occupies between 5 and 99% of the inner volume. In addition, the outer shell can have an average wall thickness of less than 100 nanometers.

  8. Static shape control of a flat shell structure

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The eight-node and forty-DOF piezoelectric shell element were applied to shape control of a flat shell structure. By the direct and converse effects, a distributed piezoelectric sensor layer was used to monitor the shape deformation and a distributed actuator layer was used to suppresse the deflection. A finite element model was for static response of laminated shell with piezoelectric sensors/actuators was derived. The model was verified by calculating piezoelectric polymeric PVDF bimorph beam. The results are in good agreement with those obtained by theoretical analysis of Tzou[1] and Hwang[2]. A case study of the static shape control of a flat shell structure is presented.

  9. Automated Shell Theory for Rotating Structures (ASTROS)

    Science.gov (United States)

    Foster, B. J.; Thomas, J. M.

    1973-01-01

    Computer program can be used to analyze any disk or shell of revolution of arbitrary cross section under inertial loads caused by rotation about shell axis and under various static loads, including thermal gradients. Geometric shapes incorporated in program are ellipsoidal, spherical, ogival, toroidal, conical, circular plate, cylindrical, and parabolic.

  10. Comparison of Three Different Materials for Wedge-shaped Defects%3种材料修复楔状缺损的疗效观察

    Institute of Scientific and Technical Information of China (English)

    邱自力

    2011-01-01

    目的 观察采用不同材料充填修复楔状缺损的临床疗效.方法 将500颗需要进行楔状缺损修复的患牙随机分成3组,分别用3M玻璃离子水门汀(1组172颗),Z350复合树脂(2组195颗),Dyract复合体(3组133颗)充填修复楔状缺损,随访1年.结果 随访1年,1组成功率87.8%,2组成功率94.9%,3组成功率为98.5%.2组和3组之间差异无统计学意义(P>0.05),1组与2组、3组之间差异有统计学意义(P<0.05).结论 Dyract复合体和Z350复合树脂的临床疗效优于玻璃离子,是较为理想的修复楔状缺损的材料.%Objective To observe the efficacy of three different materials in the restoration of wedge-shaped defects. Methods Five hundred teeth with wedge-shaped defects were randomly divided into three groups. Wedge-shaped defects were repaired with 3M glass-ionomer cement, Z350 light-cured composite resins and Dyract complex in group 1 (172 teeth), group 2 (195 teeth) and group 3(133 teeth) .respectively. All patients were followed up for 1 year. Results The success rate in group 1 (87. 8%) was significantly lower than that in group 2 (94. 9%) and group 3 (98. 5 %) (P<0. 05). Conclusion Dyract complex and Z350 light-cured composite resins are superior to 3M glass-ionomer and can be considered as the ideal choices for restoring wedge-shaped defects.

  11. Structure and Property Characterization of Oyster Shell Cementing Material

    Institute of Scientific and Technical Information of China (English)

    钟彬杨; 周强; 单昌锋; 于岩

    2012-01-01

    Oyster shell powder was used as the admixture of ordinary portland cement.The effects of different addition amounts and grinding ways on the strength and stability of cement mortar were discussed and proper addition amount of oyster shell powder was determined.The structure and property changes of cementing samples with different oyster shell powder contents were tested by XRD and SEM means.The results revealed that compressive and rupture strengths of the sample with 10% oyster shell powder was close to those of the original one without addition.Stability experiment showed that the sample prepared by pat method had smooth surface without crack and significant expansion or shrinkage after pre-curing and boiling,which indicated that cementing material dosed with oyster shell powder had fine stability.XRD and SEM observation showed that oyster shell independently exists in the cementing material.

  12. Nuclear Quadrupole Moments and Nuclear Shell Structure

    Science.gov (United States)

    Townes, C. H.; Foley, H. M.; Low, W.

    1950-06-23

    Describes a simple model, based on nuclear shell considerations, which leads to the proper behavior of known nuclear quadrupole moments, although predictions of the magnitudes of some quadrupole moments are seriously in error.

  13. 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.

  14. 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-bearing...... element analysis software Abaqus as a Python script, which translates the information to an Abaqus CAE-model. In pyFormex the model has been prepared for applying the meshing in Abaqus, by allocation of edge seeds, and by defining geometry sets for easy handling....... at Ghent University, has been used to accommodate a parametric generation of plate shell structures. This generation includes the basic facetted shell geometry, joint areas that reproduce given connection characteristics, loads and boundary conditions. From pyFormex the model is exported to the finite...

  15. 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.

  16. 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

  17. Interface Fracture in Adhesively Bonded Shell Structures

    DEFF Research Database (Denmark)

    Jensen, Henrik Myhre

    2007-01-01

    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...... stress required to propagate the crack under quasi-static conditions. The fracture mechanical model is theoretically sound and it is accurate and numerically stable. The cohesive zone model has some advantages over the fracture mechanics based model. It is easier to generalise the cohesive zone model...... to take into account effects such as plastic deformation in the adhering shells, and to take into account effects of large local curvatures of the interface crack front. The comparison shows a convergence of the results based on the cohesive zone model towards the results based on a fracture mechanics...

  18. 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...

  19. Stress Analysis of Ellipsoidal Shell with Inner Guide Structure

    Institute of Scientific and Technical Information of China (English)

    Wei-Wei Zhang; Xiao-Song Wang; Meng Chen; Shi-Jian Yuan

    2014-01-01

    In order to overcome stress concentration and increase fatigue life of ellipsoidal shells with inner guide structure, the stress analysis for strength check is very important. Owing to the main sectional profile with ellipsoidal shape, the stress distribution for perfect ellipsoidal shell is firstly conducted based on the theoretical calculation and strain gauges measurement. The experiment results show that the stresses increase gradually from pole region to equatorial plane, but still within elastic range. Secondly, strain gauge measurement for ellipsoidal shells with inner guide structure is conducted. The results show that stresses are concentrated at the vicinity of bottom plate and beyond elastic range, so the structural redesign is needed. Finally based on the analysis mentioned above, a redesigned structure with local thickening is proposed. Experimental research shows that the stress varies more even after structural redesign and within allowable range. Numerical simulation shows that both the deformation and fatigue life after redesign are acceptable.

  20. The Coupling Effect of Spatial Reticulated Shell Structure with Cables

    Institute of Scientific and Technical Information of China (English)

    MA Jun; ZHOU Dai; FU Xu-chen

    2005-01-01

    The spatial reticulated shell structure with cables (RSC) is a kind of coupling working system, which consists of flexible cables, reticulated shell structure (RS) and tower columns. The dynamic analysis of RSC based on the coupling model was carried out. Three kinds of elements such as the spatial bar element, cable element and beam element were introduced to analyze the reticulated shell, cable and tower column respectively. Furthermore,such parameter influences as structural boundary conditions, grid configuration, the span-to-depth ratio and the arrangement of cable system upon structural dynamics were analyzed. The structural vibration modes can be divided into four groups based on some numerical examples. And the frequencies in the same group are very close while the frequencies in different groups are different from each other obviously. It is clear that the sequence of the appearance of the each mode group heavily depends on the comparative stiffness of the tower column system, RS and cables.

  1. Structural and Acoustic Responses of a Submerged Stiffened Conical Shell

    Directory of Open Access Journals (Sweden)

    Meixia Chen

    2014-01-01

    Full Text Available This paper studies the vibrational behavior and far-field sound radiation of a submerged stiffened conical shell at low frequencies. The solution for the dynamic response of the conical shell is presented in the form of a power series. A smeared approach is used to model the ring stiffeners. Fluid loading is taken into account by dividing the conical shell into narrow strips which are considered to be local cylindrical shells. The far-field sound pressure is solved by the Element Radiation Superposition Method. Excitations in two directions are considered to simulate the loading on the surface of the conical shell. These excitations are applied along the generator and normal to the surface of the conical shell. The contributions from the individual circumferential modes on the structural responses of the conical shell are studied. The effects of the external fluid loading and stiffeners are discussed. The results from the analytical models are validated by numerical results from a fully coupled finite element/boundary element model.

  2. 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...

  3. Stress Recovery and Error Estimation for Shell Structures

    Science.gov (United States)

    Yazdani, A. A.; Riggs, H. R.; Tessler, A.

    2000-01-01

    The Penalized Discrete Least-Squares (PDLS) stress recovery (smoothing) technique developed for two dimensional linear elliptic problems is adapted here to three-dimensional shell structures. The surfaces are restricted to those which have a 2-D parametric representation, or which can be built-up of such surfaces. The proposed strategy involves mapping the finite element results to the 2-D parametric space which describes the geometry, and smoothing is carried out in the parametric space using the PDLS-based Smoothing Element Analysis (SEA). Numerical results for two well-known shell problems are presented to illustrate the performance of SEA/PDLS for these problems. The recovered stresses are used in the Zienkiewicz-Zhu a posteriori error estimator. The estimated errors are used to demonstrate the performance of SEA-recovered stresses in automated adaptive mesh refinement of shell structures. The numerical results are encouraging. Further testing involving more complex, practical structures is necessary.

  4. Perspective: Structure and ultrafast dynamics of biomolecular hydration shells

    Directory of Open Access Journals (Sweden)

    Damien Laage

    2017-07-01

    Full Text Available The structure and function of biomolecules can be strongly influenced by their hydration shells. A key challenge is thus to determine the extent to which these shells differ from bulk water, since the structural fluctuations and molecular excitations of hydrating water molecules within these shells can cover a broad range in both space and time. Recent progress in theory, molecular dynamics simulations, and ultrafast vibrational spectroscopy has led to new and detailed insight into the fluctuations of water structure, elementary water motions, and electric fields at hydrated biointerfaces. Here, we discuss some central aspects of these advances, focusing on elementary molecular mechanisms and processes of hydration on a femto- to picosecond time scale, with some special attention given to several issues subject to debate.

  5. 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

  6. Foraminiferal shell structures: additional cavity systems produced by supplemental skeletons

    Directory of Open Access Journals (Sweden)

    Davide Bassi

    2006-04-01

    Full Text Available This is the second part of the article, published in Mus. Sci. Nat. vol. 2, which illustrates the larger foraminiferal shell structures. In this poster intercoluclar space, canal system, umbilical cavity system, enveloping canal system, and interlamellar cavity system are described and illustrated.

  7. Dynamic fracture modeling in shell structures based on XFEM

    NARCIS (Netherlands)

    Larsson, R.; Mediavilla, J.; Fagerström, M.

    2011-01-01

    Through-the-thickness crack propagation in thin-walled structures is dealt with in this paper. The formulation is based on the cohesive zone concept applied to a kinematically consistent shell model enhanced with an XFEM-based discontinuous kinematical representation. The resulting formulation compr

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

    Science.gov (United States)

    Clausen, Anders; Andreassen, Erik; Sigmund, Ole

    2017-08-01

    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 the performance of porous structures due to the sandwich effect. Furthermore, the paper introduces improved filter boundary conditions to ensure a completely uniform coating thickness at the design domain boundary.

  9. Ion Structure Near a Core-Shell Dielectric Nanoparticle

    Science.gov (United States)

    Ma, Manman; Gan, Zecheng; Xu, Zhenli

    2017-02-01

    A generalized image charge formulation is proposed for the Green's function of a core-shell dielectric nanoparticle for which theoretical and simulation investigations are rarely reported due to the difficulty of resolving the dielectric heterogeneity. Based on the formulation, an efficient and accurate algorithm is developed for calculating electrostatic polarization charges of mobile ions, allowing us to study related physical systems using the Monte Carlo algorithm. The computer simulations show that a fine-tuning of the shell thickness or the ion-interface correlation strength can greatly alter electric double-layer structures and capacitances, owing to the complicated interplay between dielectric boundary effects and ion-interface correlations.

  10. Investigation of stresses in facetted glass shell structures

    DEFF Research Database (Denmark)

    Bagger, Anne; Jönsson, Jeppe; Wester, Ture

    2007-01-01

    The typical use of triangular and quadrangular facets in doubly curved facetted shells requires the use of triangulated truss systems or quadrangular truss framing with diagonals or cross tension cabling. In such a structure, the load carrying ability is based on concentrated forces in the framing...... system, while the glass merely serves as a separation of the inside environment from the outside. In this paper facetted glass shell structures with three way vertices, i.e. with three adjoining edges in each vertex are considered, since the load carrying ability of such a structure is achieved primarily...... 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...

  11. Better Finite-Element Analysis of Composite Shell Structures

    Science.gov (United States)

    Clarke, Gregory

    2007-01-01

    A computer program implements a finite-element-based method of predicting the deformations of thin aerospace structures made of isotropic materials or anisotropic fiber-reinforced composite materials. The technique and corresponding software are applicable to thin shell structures in general and are particularly useful for analysis of thin beamlike members having open cross-sections (e.g. I-beams and C-channels) in which significant warping can occur.

  12. Fluid-structure coupled analysis of underwater cylindrical shells

    Institute of Scientific and Technical Information of China (English)

    AI Shang-mao; SUN Li-ping

    2008-01-01

    Underwater cylindrical shell structures have been found a wide of application in many engineering fields,such as the element of marine,oil platforms,etc.The coupled vibration analysis is a hot issue for these underwater structures.The vibration characteristics of underwater structures are influenced not only by hydrodynamic pressure but also by hydrostatic pressure corresponding to different water depths.In this study,an acoustic finite element method was used to evaluate the underwater structures.Taken the hydrostatic pressure into account in terms of initial stress stiffness,an acoustical fluid-structure coupled analysis of underwater cylindrical shells has been made to study the effect of hydrodynamic pressures on natural frequency and sound radiation.By comparing with the frequencies obtained by the acoustic finite element method and by the added mass method based on the Bessel function,the validity of present analysis was checked.Finally,test samples of the sound radiation of stiffened cylindrical shells were acquired by a harmonic acoustic analysis.The results showed that hydrostatic pressure plays an important role in determining a large submerged body motion,and the characteristics of sound radiation change with water depth. Furthermore,the analysis methods and the results are of significant reference value for studies of other complicated submarine structures.

  13. Cu cluster shell structure at elevated temperatures

    DEFF Research Database (Denmark)

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

    1991-01-01

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

  14. 老年牙齿楔状缺损患者165例临床分析及预防措施研究%Clinical Analysis and Preventive Measures of 165 Elderly Patients with Wedge-shaped Defects

    Institute of Scientific and Technical Information of China (English)

    杨士杰

    2011-01-01

    目的 分析老年牙齿楔状缺损患者的发病特点,探讨有效的临床预防措施.方法 选择2007年11月-2010年10月清苑县妇幼保健院就诊的老年牙齿楔状缺损患者165例,记录患者的患病情况并采用提间的方式对与发病可能有关的情况进行调查.结果 老年牙齿楔状缺损好发于第一双尖牙,且楔缺损害以盘型,2度更为常见;横刷法刷牙、刷牙次数≥3次/d、喜食酸性食物以及牙周退缩者更容易发生楔状缺损.结论 临床医生应该掌握老年牙齿楔状缺损的发病特点,针对性进行宣传教育工作,以减少牙齿楔状缺损的发病率.%Objective To analyze the onset characteristics of elderly patients with wedge - shaped defects, and to explore the effective clinical preventive measures. Methods One hundred and sixty - five elderly patients with wedgeshaped defects hospitalized in the Maternal and Child Health Hospital of Qingyuan County from November 2007 to October 2010 were enrolled in this study. Their sickness status was recorded and the related situations of the disease were surveyed by questionnaires. Results Wedge- shaped defects in the first premolar were commonly seen in elderly patients, moreover, the disc wedge and type 2 degrees were more common in the lack of damage. The patients with cross - brushing method, brushing frequency≥3 times/day, eating acidic foods and back by periodontal wedge- shaped defect were more likely to occur wedge - shaped defects. Conclusions Dentists should grasp the onset characteristics of elderly patients with wedge - shaped defects and develop targeted publicity and education so as to reduce the incidence of wedge- shaped defects.

  15. 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.

  16. Direct imaging the upconversion nanocrystal core/shell structure at the subnanometer level: shell thickness dependence in upconverting optical properties.

    Science.gov (United States)

    Zhang, Fan; Che, Renchao; Li, Xiaomin; Yao, Chi; Yang, Jianping; Shen, Dengke; Hu, Pan; Li, Wei; Zhao, Dongyuan

    2012-06-13

    Lanthanide-doped upconversion nanoparticles have shown considerable promise in solid-state lasers, three-dimensional flat-panel displays, and solar cells and especially biological labeling and imaging. It has been demonstrated extensively that the epitaxial coating of upconversion (UC) core crystals with a lattice-matched shell can passivate the core and enhance the overall upconversion emission intensity of the materials. However, there are few papers that report a precise link between the shell thickness of core/shell nanoparticles and their optical properties. This is mainly because rare earth fluoride upconversion core/shell structures have only been inferred from indirect measurements to date. Herein, a reproducible method to grow a hexagonal NaGdF(4) shell on NaYF(4):Yb,Er nanocrystals with monolayer control thickness is demonstrated for the first time. On the basis of the cryo-transmission electron microscopy, rigorous electron energy loss spectroscopy, and high-angle annular dark-field investigations on the core/shell structure under a low operation temperature (96 K), direct imaging the NaYF(4):Yb,Er@NaGdF(4) nanocrystal core/shell structure at the subnanometer level was realized for the first time. Furthermore, a strong linear link between the NaGdF(4) shell thickness and the optical response of the hexagonal NaYF(4):Yb,Er@NaGdF(4) core/shell nanocrystals has been established. During the epitaxial growth of the NaGdF(4) shell layer by layer, surface defects of the nanocrystals can be gradually passivated by the homogeneous shell deposition process, which results in the obvious enhancement in overall UC emission intensity and lifetime and is more resistant to quenching by water molecules.

  17. Shell structure and orbit bifurcations in finite fermion systems

    Energy Technology Data Exchange (ETDEWEB)

    Magner, A. G., E-mail: magner@kinr.kiev.ua; Yatsyshyn, I. S. [National Academy of Sciences of Ukraine, Institute for Nuclear Research (Ukraine); Arita, K. [Nagoya Institute of Technology, Department of Physics (Japan); Brack, M. [University of Regensburg, Institute for Theoretical Physics (Germany)

    2011-10-15

    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).

  18. 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.

  19. Electronic shell and supershell structure in graphene flakes

    CERN Document Server

    Manninen, M; Akola, J

    2008-01-01

    We use a simple tight-binding (TB) model to study electronic properties of free graphene flakes. Valence electrons of triangular graphene flakes show a shell and supershell structure which follows an analytical expression derived from the solution of the wave equation for triangular cavity. However, the solution has different selection rules for triangles with armchair and zigzag edges, and roughly 40000 atoms are needed to see clearly the first supershell oscillation. In the case of spherical flakes, the edge states of the zigzag regions dominate the shell structure which is thus sensitive to the flake diameter and center. A potential well that is made with external gates cannot have true bound states in graphene due to the zero energy band gap. However, it can cause strong resonances in the conduction band.

  20. Synergetic effect of organic cores and inorganic shells for core/shell structured composite abrasives for chemical mechanical planarization

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yang, E-mail: cy.jpu@126.com [School of Materials Science and Engineering, Changzhou University, Changzhou, Jiangsu 213164 (China); Li, Zhina [School of Materials Science and Engineering, Changzhou University, Changzhou, Jiangsu 213164 (China); Miao, Naiming [School of Mechanical Engineering, Changzhou University, Changzhou, Jiangsu 213016 (China)

    2014-09-30

    Highlights: • The damage-free polishing mechanism of core/shell composite abrasive was explored. • The organic core is help to decrease surface roughness and mechanical damages. • The inorganic shell is in favor of improving material removal rate. • The enhanced CMP behavior is due to the synergistic effect between core and shell. - Abstract: Core/shell structured organic/inorganic composite microspheres has an important potential application in efficient and damage-free chemical mechanical planarization/polishing (CMP) as a kind of novel abrasive due to its uniform non-rigid mechanical property. However, the synergistic effect of material removal between organic cores and inorganic shells of composite abrasives is ambiguous. In this work, oxide-CMP performances of various slurries, containing polystyrene (PS) spheres, solid abrasives (SiO{sub 2} or CeO{sub 2}), mixed abrasives ((PS + SiO{sub 2}) or (PS + CeO{sub 2})), core/shell composites (PS/SiO{sub 2} or PS/CeO{sub 2}), were investigated by atomic force microscopy. Experiment results indicated that the surfaces polished by composite abrasives exhibited lower surface roughness, fewer scratches as well as lower topographical variations than those by other type of abrasives. The core/shell structure of composite abrasives plays an important role in improving CMP behavior. Moreover, the organic cores are mainly beneficial to decrease surface roughness and mechanical damages, and the inorganic shells are in favor of improving material removal rate.

  1. Shell

    OpenAIRE

    Harper, Catherine

    2006-01-01

    Susie MacMurray's Shell installation manifests in Pallant House Gallery, Chichester, like some pulsing exotica, a heavily-textured wall-paper, darkly decorative, heavily luxurious, broodingly present, with more than a hint of the uncanny or the gothic. A remarkable undertaking by an artist of significance, this work's life-span will be just one year, and then it will disappear, leaving no physical trace, but undoubtedly contributing in a much less tangible way to an already rich layering of n...

  2. Two Kinds of Repair Methods for Teeth Depth of the Wedge-shaped Defect%深度楔状缺损两种修复方法的临床疗效观察

    Institute of Scientific and Technical Information of China (English)

    李慧良; 杨令云

    2011-01-01

    To compare the observed light-cured calcium hydroxide bottom composite Dyract after repair and the direct use of Fuji II glass ionomer cement neck deep wedge-shaped defects in dental clinical efficacy. 178 cases of tooth neck deep wedge-shaped defect in patients with 412 teeth were randomly divided into two groups. Group 1 Fuji II glass ionomer direct repair. Group 2 using light-cured calcium hydroxide bottom composite Dyract after repair. 6 -24 months follow-up after, the results were significantly different after two years (P0. 05). 2 years after the first set of edge adaptation, secondary caries and periodontal dental pulp are superior to group 2 (P<0. 05). Repair of glass ionomer cement direct treatment of wedge-shaped defects over the depth of light curing calcium hydroxide to bottom with Dyract complex repair, Fujill direct filling of glass ionomer cement is an ideal depth of wedge-shaped defect repair technology.%通过光固化氢氧化钙垫底后Dyract复合体修复和直接用Fuji Ⅱ玻璃离子水门汀分别修复牙颈部深度楔状缺损,临床观察6个月~24个月.对二者的治疗效果进行研究分析,认为玻璃离子水门汀直接修复深度楔状缺损治疗效果优于以光固化氢氧化钙垫底用Dyract复合体修复,FujiⅡ玻璃离子水门汀直接充填是一种较理想的修复深度楔状缺损技术.

  3. 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

    2014-01-01

    $\\textbf{Background:}$ 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...

  4. Three-body forces and shell structure in calcium isotopes

    CERN Document Server

    Holt, Jason D; Schwenk, Achim; Suzuki, Toshio

    2010-01-01

    Understanding and predicting the formation of shell structure from nuclear forces is a central challenge for nuclear physics. While the magic numbers N=2,8,20 are generally well understood, N=28 is the first standard magic number that is not reproduced in microscopic theories with two-nucleon forces. In this Letter, we show that three-nucleon forces give rise to repulsive interactions between two valence neutrons that correctly lead to 48Ca as a magic nucleus, with a high 2+ excitation energy and a concentrated magnetic dipole transition strength. Towards the neutron drip line, we robustly predict a shell closure at N=34. The repulsive three-nucleon mechanism improves the agreement with experimental binding energies and suggests the drip line around 60Ca.

  5. Pore structure of the activated coconut shell charcoal carbon

    Science.gov (United States)

    Budi, E.; Nasbey, H.; Yuniarti, B. D. P.; Nurmayatri, Y.; Fahdiana, J.; Budi, A. S.

    2014-09-01

    The development of activated carbon from coconut shell charcoal has been investigated by using physical method to determine the influence of activation parameters in term of temperature, argon gas pressure and time period on the pore structure of the activated carbon. The coconut shell charcoal was produced by pyrolisis process at temperature of about 75 - 150 °C for 6 hours. The charcoal was activated at various temperature (532, 700 and 868 °C), argon gas pressure (6.59, 15 and 23.4 kgf/cm2) and time period of (10, 60 and 120 minutes). The results showed that the pores size were reduced and distributed uniformly as the activation parameters are increased.

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

    Science.gov (United States)

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

    2013-09-16

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

  7. Magnetic mirror structure for testing shell-type quadrupole coils

    Energy Technology Data Exchange (ETDEWEB)

    Andreev, N.; Barzi, E.; Bossert, R.; Chlachidze, G.; Kashikhin, V.S.; Kashikhin, V.V.; Lamm, M.J.; Nobrega, F.; Novitski, I.; Tartaglia, N.; Turrioni, D.; /Fermilab

    2009-10-01

    This paper presents magnetic and mechanical designs and analyses of the quadrupole mirror structure to test single shell-type quadrupole coils. Several quadrupole coils made of different Nb{sub 3}Sn strands, cable insulation and pole materials were tested using this structure at 4.5 and 1.9 K. The coils were instrumented with voltage taps, spot heaters, temperature sensors and strain gauges to study their mechanical and thermal properties and quench performance. The results of the quadrupole mirror model assembly and test are reported and discussed.

  8. Magnetic mirror structure for testing shell-type quadrupole coils

    Energy Technology Data Exchange (ETDEWEB)

    Andreev, N.; Barzi, E.; Bossert, R.; Chlachidze, G.; Kashikhin, V.S.; Kashikhin, V.V.; Lamm, M.J.; Nobrega, F.; Novitski, I.; Tartaglia, N.; Turrioni, D.; /Fermilab

    2009-10-01

    This paper presents magnetic and mechanical designs and analyses of the quadrupole mirror structure to test single shell-type quadrupole coils. Several quadrupole coils made of different Nb{sub 3}Sn strands, cable insulation and pole materials were tested using this structure at 4.5 and 1.9 K. The coils were instrumented with voltage taps, spot heaters, temperature sensors and strain gauges to study their mechanical and thermal properties and quench performance. The results of the quadrupole mirror model assembly and test are reported and discussed.

  9. 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

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

    Science.gov (United States)

    Cao, Rui; Bolton, J. Stuart

    2016-09-01

    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.

  11. Investigation of physical vapor deposition techniques of conformal shell coating for core/shell structures by Monte Carlo simulations

    Energy Technology Data Exchange (ETDEWEB)

    Cansizoglu, H., E-mail: hxis@ualr.edu; Yurukcu, M.; Cansizoglu, M.F.; Karabacak, T.

    2015-05-29

    Vertically aligned core/shell nanowire (nanorod) arrays are favorable candidates in many nano-scale devices such as solar cells, detectors, and integrated circuits. The quality of the shell coating around nanowire arrays is as crucial as the quality of the nanowires in device applications. For this reason, we worked on different physical vapor deposition (PVD) techniques and conducted Monte Carlo simulations to estimate the best deposition technique for a conformal shell coating. Our results show that a small angle (≤ 45°) between incoming flux of particles and the substrate surface normal is necessary for PVD techniques with a directional incoming flux (e.g. thermal or e-beam evaporation) for a reasonable conformal coating. On the other hand, PVD techniques with an angular flux distribution (e.g. sputtering) can provide a fairly conformal shell coating around nanowire arrays without a need of small angle deposition. We also studied the shape effect of the arrays on the conformality of the coating and discovered that arrays of the tapered-top nanorods and the pyramids can be coated with a more conformal and thicker coating compared to the coating on the arrays of flat-top nanowires due to their larger openings in between structures. Our results indicate that conventional PVD techniques, which offer low cost and large scale thin film fabrication, can be utilized for highly conformal and uniform shell coating formation in core/shell nanowire device applications. - Highlights: • We examined the shell coating growth in core/shell nanostructures. • We investigated the effect of physical vapor deposition method on the conformality of the shell. • We used Monte Carlo simulations to simulate the shell growth on nanowire templates. • Angular atomic flux (i.e., sputtering at high pressure) leads to conformal and uniform coatings. • A small angle (< 45°) to the directional flux needs to be introduced for conformal coatings.

  12. Analysis and experiment of a vessels shell cover in submarine structure

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yu-li; ZENG Guang-wu

    2004-01-01

    This paper aims to achieve analysis and experiment results that relate to mechanics capability and structural parameter of a special saddle shell of revolution. Theoretically speaking, the saddle shell of revolution consists of a toroidal shell and a spherical shell. The shells simultaneous equations can be solved with harmonious terms. Where, the fundamental equations can be solved by asymptotic exponential perturbation method. The equations of special solution can be solved by Hovozhilovs special solution. This new idea is from a study of some existing solutions of the toroidal shell. The results have been proved by compared with some experimental results. The experiments aims to study the effect caused by change of material parameter, or by change of different geometric dimensions of the saddle shell, which include the change of thickness, the change of radius of shell, and the change of ribs. Finally, the accepted product of the saddle shell were reinforced by a toroidal rib has been submitted.

  13. The similitude research on underwater complex shell-structure based on SEA

    Institute of Scientific and Technical Information of China (English)

    WANG San-de; YANG De-sen; SHI Sheng-guo; FANG Er-zheng

    2005-01-01

    In this paper, the vibration and sound radiation of the underwater complex shell-structure which is the cylindrical shell with hemi-spherical shell on the ends are studied by statistical energy analysis (SEA). The whole shell-structure is divided into the four subsystems, and the SEA physical model and power flow balance equations among these subsystems are established. The similitude relations of input power, coupling loss factor and modal density of the subsystems between the complex shell-structure and its scaled-down model are analyzed. According to the similitude theory and power flow balance equations, when the immerged shell-structures are excited, the similar relations of spatially averaged vibration response and underwater radiating sound power are established for the complex shell-structure and its scaled-down model.

  14. 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....

  15. The shells of atomic structure in metallic glasses

    Science.gov (United States)

    Pan, S. P.; Feng, S. D.; Qiao, J. W.; Dong, B. S.; Qin, J. Y.

    2016-02-01

    We proposed a scheme to describe the spatial correlation between two atoms in metallic glasses. Pair distribution function in a model iron was fully decomposed into several shells and can be presented as the spread of nearest neighbor correlation via distance. Moreover, angle distribution function can also be decomposed into groups. We demonstrate that there is close correlation between pair distribution function and angle distribution function for metallic glasses. We think that our results are very helpful understanding the atomic structure of metallic glasses.

  16. THE LAYOUT OPTIMIZATION OF STIFFENERS FOR PLATE-SHELL STRUCTURES

    Institute of Scientific and Technical Information of China (English)

    Chen Suhuan; Yang Zhijun

    2005-01-01

    The plate-shell structures with stiffeners are widely used in a broad range of engineering structures. This study presents the layout optimization of stiffeners. The minimum weight of stiffeners is taken as the objective function with the global stiffness constraint. In the layout optimization, the stiffeners should be placed at the locations with high strain energy/or stress.Conversely, elements of stiffeners with a small strain energy/or stress are considered to be used inefficiently and can be removed. Thus, to identify the element efficiency so that most inefficiently used elements of stiffeners can be removed, the element sensitivity of the strain energy of stiffeners is introduced, and a search criterion for locations of stiffeners is presented. The layout optimization approach is given for determining which elements of the stiffeners need to be kept or removed. In each iterative design, a high efficiency reanalysis approach is used to reduce the computational effort. The present approach is implemented for the layout optimization of stiffeners for a bunker loaded by the hydrostatic pressure. The numerical results show that the present approach is effective for dealing with layout optimization of stiffeners for plate-shell structures.

  17. Structure of Supergiant Shells in the Large Magellanic Cloud

    CERN Document Server

    Book, Laura G; Gruendl, Robert A

    2007-01-01

    Nine supergiant shells (SGSs) have been identified in the Large Magellanic Cloud (LMC) based on H-alpha images, and twenty-three SGSs have been reported based on HI 21-cm line observations, but these sets do not always identify the same structures. We have examined the physical structure of the optically identified SGSs using HI channel maps and P-V diagrams to analyze the gas kinematics. There is good evidence for seven of the nine optically identified SGSs to be true shells. Of these seven H-alpha SGSs, four are the ionized inner walls of HI SGSs, while three are an ionized portion of a larger and more complex HI structure. All of the H-alpha SGSs are identified as such because they have OB associations along the periphery or in the center, with younger OB associations more often found along the periphery. After roughly 12 Myrs, if no new OB associations have been formed a SGS will cease to be identifiable at visible wavelengths. Thus, the presence and location of ionizing sources is the main distinction be...

  18. Comparison of the Behaviour of Curved and Straight Types of Steel Shell Roof Structures

    OpenAIRE

    Behnamasl, Mana

    2010-01-01

    ABSTRACT: In this research, the straight and curved models of the steel shell roof with different plates were analysed, designed and the results were compared with one another. Through this exercise it is aimed at achieving an ideal shell roof structure which could cover a larger surface. Therefore, three types of shell roofs were considered duopitch, cylindrical and dome and the main objective was to compare the straight and curved model of the shells. According to the findings of the liter...

  19. Projected shell model study of quasiparticle structure of arsenic isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Verma, Preeti; Sharma, Chetan; Singh, Suram [Department of Physics and Electronics, University of Jammu, Jammu, 180006 (India); Bharti, Arun, E-mail: arunbharti_2003@yahoo.co.in [Department of Physics and Electronics, University of Jammu, Jammu, 180006 (India); Khosa, S.K. [Department of Physics and Electronics, University of Jammu, Jammu, 180006 (India); Bhat, G.H. [Department of Physics, University of Kashmir, Srinagar, 190006 (India); Sheikh, J.A. [Department of Physics, University of Kashmir, Srinagar, 190006 (India); Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996 (United States)

    2013-11-20

    Odd-mass isotopic chain of {sup 67–79}As has been studied within the context of the projected shell model. Deformed single-particle states generated by the standard Nilsson potential are used to calculate various nuclear structure properties like yrast spectra, rotational frequencies and reduced transition probabilities. The study of band structures of these As nuclei based on the band diagrams indicates the presence of multi-quasiparticle structure in the high spin realm of these nuclei. Rotational alignment phenomenon has also been studied in terms of band crossing which is understood to occur due to the rotational alignment of g{sub 9/2} neutron pair. We also have compared the results of the present calculations with the available experimental as well as the other theoretical data and an overall good agreement has been achieved between the two.

  20. The shell model approach: Key to hadron structure

    Energy Technology Data Exchange (ETDEWEB)

    Lipkin, H.J. (Weizmann Inst. of Science, Rehovoth (Israel). Dept. of Nuclear Physics)

    1989-08-14

    A shell model approach leads to a simple constituent quark model for hadron structure in which mesons and baryons consist only of constituent quarks. Hadron masses are the sums of the constituent quark effective masses and a hyperfine interaction inversely proportional to the product of these same masses. Hadron masses and magnetic moments are related by the assumption that the same effective mass parameter appears in the additive mass term, the hyperfine interaction, and the quark magnetic moment, both in mesons and baryons. The analysis pinpoints the physical assumptions needed for each relation and gives two new mass relations. Application to weak decays and recent polarized EMC data confirms conclusions previously obtained that the current quark contribution to the spin structure of the proton vanishes, but without need for the questionable assumption of SU(3) symmetry relating hyperon decays and proton structure. SU(3) symmetry breaking is clarified. 24 refs.

  1. 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

  2. Comparison of the clinical effects of two kinds of materials for restoration of the wedge-shaped defect%两种楔状缺损修复材料的临床效果比较

    Institute of Scientific and Technical Information of China (English)

    霍志强

    2013-01-01

    目的 探讨两种修复楔状缺损材料的应用效果.方法 将294例患者共1242颗患牙随机分为两组.实验组:149例患者648颗患牙,采用Dyract AP复合体修复.对照组:145例患者594颗患牙,采用3M-Vitemer新一代光固化玻璃离子水门汀修复.修复后1~2年进行复查,观察两组的临床效果.结果 两种修复材料均显示出优良的固位性能和边缘密合性,对牙髓和牙周组织均无刺激;实验组和对照组的成功率分别为92.59%和88.38%,两组差异具有统计学意义(P<0.05).结论 两种材料修复楔状缺损均可获得较好的临床效果,其中复合体修复的成功率高于光固化水门汀.%Objective To evaluate the application effect of two kinds of materials for restoration of the wedge-shaped defect.Methods 294 patients with a total of 1242 teeth with wedge-shaped defect enrolled and randomly divided into two groups.648 teeth with wedge-shaped defect of 149 patients in the experimental group were repaired with the Dyract AP complex.While 594 teeth with wedge-shaped defect of 145 patients in the control group were repaired with a new generation of 3M-Vitemer light-cured glass ionomer cement.The patients were recalled 1-2 years after restoration to evaluate the clinical effects of two kinds of materials.Results Both of the two kinds of repairing materials showed excellent retention and edge sealing,and no irritation to pulp and periodontal tissue.The success rate of the experimental group and the control group were 92.59% and 88.38% respectively,and there was statistical difference between the success rates of the two groups (P<0.05).Conclusion Both of the two kinds of materials for restoration of dental wedge-shaped defects in the present manuscript can obtain good clinical effect,but the success rate in reparing the wedge-shaped defect with the complex is higher than that with light-cured cement material.

  3. Active vibration control of ring-stiffened cylindrical shell structure using macro fiber composite actuators.

    Science.gov (United States)

    Sohn, Jung Woo; Jeon, Juncheol; Choi, Seung-Bok

    2014-10-01

    Vibration control performance of the ring-stiffened cylindrical shell structure is experimentally evaluated in this work. In order to achieve high control performance, advanced flexible piezoelectric actuator whose commercial name is Macro-Fiber Composite (MFC) is adapted to the shell structure. Governing equation is derived by finite element method and dynamic characteristics are investigated from the modal analysis results. Ring-stiffened cylindrical shell structure is then manufactured and modal test is conducted to verify modal analysis results. An optimal controller is designed and experimentally realized to the proposed shell structure system. Vibration control performance is experimentally evaluated in time domain and verified by simulated control results.

  4. THE RELATION OF SALIVARY FLOW RATE,PH AND BUTTER CAPACITY TO WEDGE-SHAPE DEFECTS OF TOOTH NECK%老年人唾液与牙颈部楔状缺损的关系

    Institute of Scientific and Technical Information of China (English)

    林南雁; 姜毅; 东智安

    2001-01-01

    Objective:The aim of the study was to inestigate the relation of some saliva factors to wedge-shape defects of tooth in the elderly.Methods:The material comprised 84 subjects,whose wedge-shape defects of tooth were evaluated with Smith' tooth wear index.According to the TWI,the subjects were divided into mild and severe group.Saliva samples in stimuli wax from subjects were measured.Results:No different was found between groups in salivary flow rate,pH and buffer capacity.Conclusion:The salivary pH and buffer capacity has no significant relation to wedge-shape defects of tooth.%目的:调查老年人唾液流速、pH值及缓冲力的变化与牙齿颈部楔状缺损的关系.方法:选84名老年人,采用Smith牙齿磨损指数分度检查全口牙齿颈楔状缺损,并据缺损程度分组;检测新鲜刺激唾液的流速、pH值及缓冲力.结果:牙齿颈部楔状缺损程度不同组间与唾液流速、pH值及缓冲无差异.结论:牙颈部楔状缺损与唾液流速、pH及缓冲力无明显关系.

  5. 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

  6. 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.

  7. 可摘局部义齿基牙楔状缺损充填修复的临床疗效分析%Removable Partial Denture Restoration of Wedge-shaped Defect Clinical Analysis

    Institute of Scientific and Technical Information of China (English)

    田云霞

    2013-01-01

      目的:分析研究临床采用三种材料对可摘局部义齿基牙颈部楔状缺损的临床修复疗效.方法:选取我院口腔门诊2009年3月~2010年3月收治的62例患者174颗楔状缺损可摘局部义齿基牙,随机分为为A组、B组及C组.分别采用三种材料对其缺损部位进行修复,修复2年后采用改良的USPHS系统评价修复体的疗效.结果:A组、B组与C组比较有显著性差异(P<0.05)有统计学意义.结论:可摘局部义齿基牙楔状缺损应及早黏结修复以改善该处的集中应力状况,以提高楔状缺损患者的生活质量.%Objective:To study three glass ionomer cements materials for removable partial denture abutments cervical wedge-shaped defects of clinical therapeutic effect of repair.Methods:In our hospital in 2009 March~2010 March dental clinic in 62 patients 174 wedge-shaped defect with removable partial denture abutments,respectively,using three kinds of materials on the defect repair,restoration after 2 years by using the improved USPHS system restoration effect evaluation.Results:The amalgam group,Dyract group and GC Fuji IX composite GP glass ionomer cement group had significant difference (P<0.05) was statistically significant.Conclusion:Removable partial denture abutment teeth wedge-shaped defects should be early restorations to improve the concentrated stress condition,in order to improve the quality of life in patients with wedge shaped defect.

  8. Simulations of Line Profile Structure in Shell Galaxies

    CERN Document Server

    Jilkova, L; Krizek, M; Ebrova, I; Stoklasova, I; Bartakova, T; Bartoskova, K

    2009-01-01

    In the context of exploring mass distributions of dark matter haloes in giant ellipticals, we extend the analysis carried out Merrifield and Kuijken (1998) for stellar line profiles of shells created in nearly radial mergers of galaxies. We show that line-of-sight velocity distributions are more complex than previously predicted. We simulate shell formation and analyze the detectability of spectroscopic signatures of shells after convolution with spectral PSFs.

  9. New Variational Techniques for Acoustic Radiation and Scattering From Elastic Shell Structures

    Science.gov (United States)

    1993-12-20

    in structural dynamics When the mechanical energy functions are very complicated, as in the case of a doubly curved-shell, determination of the...Investigator, Professor and Woodruff Chair, School of Mechanical Enginneering , Georgia Institute of Technology. 2. Allan D. Pierce, Co-Principal...5 1. General Implementation of SVP for Bodies of Revolution ........ 7 2. Structural Dynamics for Plates and Shells

  10. 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

  11. 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.

  12. 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.

  13. A Study of Rock Mechanical Properties under the Effect of the Wedge-shaped Blade Head%楔形刃压头作用下岩石力学性能研究

    Institute of Scientific and Technical Information of China (English)

    张照煌; 叶定海; 袁昕

    2011-01-01

    楔形刃压头与岩石作用规律的研究是全断面岩石掘进机研制的基础理论.通过对楔形刃压头贯入岩石产生的现象及其与岩石相互作用规律的研究,发现在楔形刃作用下,岩石破坏的宏观表现是“跃进破碎”.岩石在跃进破碎前经历弹性变形和塑性变形,弹性变形较小,塑性变形在跃进破碎前及两相邻跃进破碎间是岩石变形的主要形式,并且作用在楔形刃上的力与楔形刃贯入岩石的深度保持着线性关系,因此,将楔形刃作用下岩石塑性变形的物理方程表示为广义胡克定律形式;提出了楔形刃作用下,岩石变形几何方程建立的单点双角度变量理论;通过楔形刃与岩石相互作用平衡方程的建立,研究了楔形刃压头作用下广义胡克定律中杨氏模量的取值.从而提出了此领域研究的新方法和新理论.%The research on the interaction between the Wedge-shaped blade head and the rock is not only the theoretical basis for developing TBM, but also the research focus of scholars at home and abroad. The study of the phenomenon of the Wedge-shaped blade head's piercing the rock and the interaction between them reveal that under the effect of the Wedge-shaped blade Head, the macro form of rock-breaking is " jump crushing. " Before that, the rock undergoes elastic deformation and plastic deformation. The rock deformation is mainly in the form of plastic deformation with minor elastic deformation plastic. The force exerted on the Wedge-shaped blade head and the cutting depth maintain linear relationship. Thus, the physical equation for rock's plastic deformation in such a case is expressed as the generalized Hooke's Law. The theory of single-point and double-angle variables is put forward. With the balance equations for the interaction between the Wedge-shaped blade head and the rock established, the value of Young modulus in terms of the generalized Hooke's Law is analyzed. Hence, a new

  14. Numerical analysis of stiffened shells of revolution. Volume 2: Users' manual for STAR-02S - shell theory automated for rotational structures - 2 (statics), digital computer program

    Science.gov (United States)

    Svalbonas, V.

    1973-01-01

    A procedure for the structural analysis of stiffened shells of revolution is presented. A digital computer program based on the Love-Reissner first order shell theory was developed. The computer program can analyze orthotropic thin shells of revolution, subjected to unsymmetric distributed loading or concentrated line loads, as well as thermal strains. The geometrical shapes of the shells which may be analyzed are described. The shell wall cross section can be a sheet, sandwich, or reinforced sheet or sandwich. General stiffness input options are also available.

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

    OpenAIRE

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

    2013-01-01

    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 excite...

  16. Wind-induced vibration of single-layer reticulated shell structures

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jian-sheng; WU Yue; SHEN Shi-zhao

    2008-01-01

    Aiming at the dynamic response of reticulated shell structures under wind load, systematic parameter analyses on wind-induced responses of Kiewitt6-6 type single-layer spherical reticulated shell structures and three-way grid single-layer cylindrical reticulated shell structures were performed with the random simulation method in time domain, including geometric parameters, structural parameters and aerodynamic parameters. Moreover, a wind-induced vibration coefficient was obtained, which can be a reference to the wind-resistance design of reticulated shell structures. The results indicate that the geometric parameters are the most important factor influencing wind-induced responses of the reticulated shell structures; the wind-induced vibration coeffi-cient is 3.0 - 3.2 for the spherical reticulated shell structures and that is 2.8 - 3.0 for the cylindrical reticula-ted shell structures, which shows that the wind-induced vibration coefficients of these two kinds of space frames are well-proportioned.

  17. Fracture mechanics analyses of partial crack closure in shell structures

    Science.gov (United States)

    Zhao, Jun

    2007-12-01

    This thesis presents the theoretical and finite element analyses of crack-face closure behavior in shells and its effect on the stress intensity factor under a bending load condition. Various shell geometries, such as spherical shell, cylindrical shell containing an axial crack, cylindrical shell containing a circumferential crack and shell with double curvatures, are all studied. In addition, the influence of material orthotropy on the crack closure effect in shells is also considered. The theoretical formulation is developed based on the shallow shell theory of Delale and Erdogan, incorporating the effect of crack-face closure at the compressive edges. The line-contact assumption, simulating the crack-face closure at the compressive edges, is employed so that the contact force at the closure edges is introduced, which can be translated to the mid-plane of the shell, accompanied by an additional distributed bending moment. The unknown contact force is computed by solving a mixed-boundary value problem iteratively, that is, along the crack length, either the normal displacement of the crack face at the compressive edges is equal to zero or the contact pressure is equal to zero. It is found that due to the curvature effects crack closure may not always occur on the entire length of the crack, depending on the direction of the bending load and the geometry of the shell. The crack-face closure influences significantly the magnitude of the stress intensity factors; it increases the membrane component but decreases the bending component. The maximum stress intensity factor is reduced by the crack-face closure. The significant influence of geometry and material orthotropy on rack closure behavior in shells is also predicted based on the analytical solutions. Three-dimensional FEA is performed to validate the theoretical solutions. It demonstrates that the crack face closure occurs actually over an area, not on a line, but the theoretical solutions of the stress intensity

  18. Gross shell structure at high spin in heavy nuclei

    CERN Document Server

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

    2004-01-01

    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 effects and these have been calculated microscopically. The data and quantal calculations are interpreted by means of the semiclassical Periodic Orbit Theory. From this new perspective, features in the moments of inertia as a function of neutron number and spin, as well as their relation to the shell energies can be understood. Gross shell effects persist up to the highest angular momenta observed.

  19. Gross shell structure at high spin in heavy nuclei

    Energy Technology Data Exchange (ETDEWEB)

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

    2003-10-07

    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.

  20. 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.

  1. Structural Lightweight Concrete Production by Using Oil Palm Shell

    Directory of Open Access Journals (Sweden)

    Habibur Rahman Sobuz

    2014-01-01

    Full Text Available Conventional building materials are widely used in a developing country like Malaysia. This type of material is costly. Oil palm shell (OPS is a type of farming solid waste in the tropical region. This paper aims to investigate strength characteristics and cost analysis of concrete produced using the gradation of OPS 0–50% on conventional coarse aggregate with the mix proportions 1 : 1.65 : 2.45, 1 : 2.5 : 3.3, and 1 : 3.3 : 4.2 by the weight of ordinary Portland cement, river sand, crushed stone, and OPS as a substitution for coarse aggregate. The corresponding w/c ratios were used: 0.45, 0.6, and 0.75, respectively, for the defined mix proportions. Test results indicate that compressive strength of concrete decreased as the percentage of the OPS increased in each mix ratio. Other properties of OPS concrete, namely, modulus of rupture, modulus of elasticity, splitting tensile strength, and density, were also determined and compared to the corresponding properties of conventional concrete. Economic analysis also indicates possible cost reduction of up to 15% due to the use of OPS as coarse aggregate. Finally, it is concluded that the use of OPS has great potential in the production of structural lightweight concrete.

  2. 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.

  3. Core-Shell-structured Dendritic Mesoporous Silica Nanoparticles for Combined Photodynamic Therapy and Antibody Delivery.

    Science.gov (United States)

    Abbaraju, Prasanna Lakshmi; Yang, Yannan; Yu, Meihua; Fu, Jianye; Xu, Chun; Yu, Chengzhong

    2017-07-04

    Multifunctional core-shell-structured dendritic mesoporous silica nanoparticles with a fullerene-doped silica core, a dendritic silica shell and large pores have been prepared. The combination of photodynamic therapy and antibody therapeutics significantly inhibits the cancer cell growth by effectively reducing the level of anti-apoptotic proteins. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. High thermal stability of core-shell structures dominated by negative interface energy.

    Science.gov (United States)

    Zhu, Yong-Fu; Zhao, Ning; Jin, Bo; Zhao, Ming; Jiang, Qing

    2017-03-29

    Nanoscale core/shell structures are of interest in catalysis due to their superior catalytic properties. Here we investigated the thermal stability of the coherent core-shell structures in a thermodynamic way by considering the impact from the core with the bulk melting point Tm(∞) lower or higher than the shell. When a low-Tm(∞) core is adopted, core-shell melting induced by the melting depression of the core does not occur upon heating because of the superheating, although the melting depression of the core can be triggered ultimately by the preferential melting of the high-Tm(∞) shell for small cores. The superheating of the core is contributed by the negative solid-solid interface energy, while the depression is originated from the positive solid-liquid interface energy. Owing to the presence of the negative interface energy, moreover, the low-Tm(∞)-core structure possesses a low difference in thermal expansion between the core and the shell, high activation energy of outward atomic diffusion from the core to shell, and low heat capacity. This result is beneficial for the core-shell structure design for its application in catalysis.

  5. 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.

  6. Clinical observation of deep dental wedge-shaped defects with three different methods%3种方法修复深度楔状缺损的临床观察

    Institute of Scientific and Technical Information of China (English)

    陈平

    2012-01-01

    Objective To explore better materials and methods for restoring deep dental wedge-shaped defects. Methods 486 teeth in 189 cases with wedge-shaped defects were randomly divided into three groups which were restored with glass inomer cement restoration, light-cured composite resin restoration and the sandwich technique respectively. Evaluation was made after restoration for 1 to 2 years respectively. Results The successful rates of glass inomer cement restoration, light-cured composite resin restoration and the sandwich technique after 1 to 2 years were 89.66%, 84.72%, 93.46% and 69.17%, 82.22%, 90.28% respectively. The successful rate of the sandwich technique group was higher than that of the other two groups. Conclusion The clinical curative effect of the sandwich technique for restoring deep dental wedge-shaped defects was better.%目的 探讨疗效较理想的修复深度楔状缺损的材料和方法.方法 189名患者的486颗患牙随机分为3组,分别用玻璃离子黏固剂修复法、光固化复合树脂修复法和夹层技术修复深度楔状缺损.修复后1~2年复查,观察其临床疗效.结果 修复1年和2年后玻璃离子黏固剂修复法、光固化复合树脂修复法和夹层技术修复的成功率分别为89.66%、84.72%、93.46%和69.17%、82.22%、90.28%.夹层技术组成功率明显高于其他2组.结论夹层技术用于修复深度楔状缺损的临床疗效较好.

  7. The study of the wedge-shaped vibration-driven robot motion in a viscous fluid forced by different oscillation laws of the internal mass

    Science.gov (United States)

    Nuriev, A. N.; Zakharova, O. S.; Zaitseva, O. N.; Yunusova, A. I.

    2016-11-01

    A rectilinear motion of a two-mass system in a viscous incompressible fluid is considered. The system consists of a shell having the form of an equilateral triangular cylinder and a movable internal mass. The motion of the system as a whole is forced by longitudinal oscillations of the internal mass relative to the shell. This mechanical system simulates a vibration-driven robot, i.e. a mobile device capable to move in a resistive medium without external moving parts. Investigation of the system is carried out by a direct numerical simulation. A comparative analysis of the characteristics of the motion and flow regimes around the vibration-driven robot is carried out for different internal mass oscillation laws.

  8. Monte Carlo Shell Model for ab initio nuclear structure

    Directory of Open Access Journals (Sweden)

    Abe T.

    2014-03-01

    Full Text Available We report on our recent application of the Monte Carlo Shell Model to no-core calculations. At the initial stage of the application, we have performed benchmark calculations in the p-shell region. Results are compared with those in the Full Configuration Interaction and No-Core Full Configuration methods. These are found to be consistent with each other within quoted uncertainties when they could be quantified. The preliminary results in Nshell = 5 reveal the onset of systematic convergence pattern.

  9. Coordination polymer core/shell structures: Preparation and up/down-conversion luminescence.

    Science.gov (United States)

    Li, Bingmei; Xu, Hualan; Xiao, Chen; Shuai, Min; Chen, Weimin; Zhong, Shengliang

    2016-10-01

    Coordination polymer (CP) core-shell nanoparticles with Gd-based CP (GdCP) as core and Eu-based CP (EuCP) as shell have been successfully prepared. Allantoin was employed as the organic building block without the assistance of any template. The composition, size and structure of the core-shell nanospheres were well characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX), powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR), thermo-gravimetric analysis (TG). Results show that the resultant cores are uniform nanospheres with diameter of approximately 45nm, while the diameters of the core-shell nanospheres are increased to approximately 60nm. The core-shell products show enhanced luminescence efficiency than the core under 980nm laser excitation and decreased down-conversion luminescence when excited at 394nm.

  10. Fast connection of large-diameter PE pipes. A new generation of heating coil welding technologies. A technical comparison between the new wedge-shaped joint and the conventional cylindrical foint for PE pipes d 1000 and larger; PE-Grossrohre im Handumdrehen verbinden. Eine neue Generation der Heizwendelschweisstechnik. Ein technischer Vergleich zwischen der neuen Keilmuffe und der herkoemmlichen zylindrischen Muffe fuer PE-Rohre d 1000 und groesser

    Energy Technology Data Exchange (ETDEWEB)

    Eckert, Robert [FRIATEC AG, Mannheim (Germany)

    2011-07-01

    Wedge-shape joints are a revolution in large-diameter pipe connection. Fitting is simplified considerably as compared to conventional cylindrical joints. Reproducible high-quality connections are achieved at only a fraction of the time formerly required. Assembly follows clear and simple rules. Anybody who can assemble a flange will be able to cope with the tightening system of the wedge-shaped joint.

  11. The structural, compositional and mechanical features of the calcite shell of the barnacle Tetraclita rufotincta.

    Science.gov (United States)

    Astachov, Liliana; Nevo, Zvi; Brosh, Tamar; Vago, Razi

    2011-09-01

    The microstructure and chemical composition of the calcite shell of the sea barnacle Tetraclita rufotincta (Pilsbry, 1916) were investigated using microscopic and analytical methods. The barnacle shell was separated mechanically into its three substructural units: outer, interior, and inner layers. The organic matrices of these structural parts were further separated into soluble and insoluble constituents and their characteristic functional groups were studied by FTIR. Investigation of the mechanical properties of the interior mass of the shell reveals remarkable viscoelastic behavior. In general, the mechanical behavior of the shell is a function of its geometry as well as of the material, of which it is constructed. In the case of T. rufotincta, as calcite is a brittle material, the elastic behavior of the shell is apparently related to its micro- and macroarchitecture. The latter enables the shell to fulfill its primary function which is to protect the organism from a hostile environment and enables its survival. Our detailed identification of the similarities and differences between the various structural components of the shell in regard to the composition and properties of the organic component will hopefully throw light on the role of organic matrices in biomineralization processes.

  12. A hybrid-stress solid-shell element for non-linear analysis of piezoelectric structures

    Institute of Scientific and Technical Information of China (English)

    SZE; K; Y

    2009-01-01

    This paper presents eight-node solid-shell elements for geometric non-linear analyze of piezoelectric structures. To subdue shear, trapezoidal and thickness locking, the assumed natural strain method and an ad hoc modified generalized laminate stiffness matrix are employed. With the generalized stresses arising from the modified generalized laminate stiffness matrix assumed to be independent from the ones obtained from the displacement, an extended Hellinger-Reissner functional can be derived. By choosing the assumed generalized stresses similar to the assumed stresses of a previous solid ele- ment, a hybrid-stress solid-shell element is formulated. The presented finite shell element is able to model arbitrary curved shell structures. Non-linear numerical examples demonstrate the ability of the proposed model to analyze nonlinear piezoelectric devices.

  13. Coupled mixed-field laminate theory and finite element for smart piezoelectric composite shell structures

    Science.gov (United States)

    Saravanos, Dimitris A.

    1996-01-01

    Mechanics for the analysis of laminated composite shells with piezoelectric actuators and sensors are presented. A new mixed-field laminate theory for piezoelectric shells is formulated in curvilinear coordinates which combines single-layer assumptions for the displacements and a layerwise representation for the electric potential. The resultant coupled governing equations for curvilinear piezoelectric laminates are described. Structural mechanics are subsequently developed and an 8-node finite-element is formulated for the static and dynamic analysis of adaptive composite structures of general laminations containing piezoelectric layers. Evaluations of the method and comparisons with reported results are presented for laminated piezoelectric-composite plates, a closed cylindrical shell with a continuous piezoceramic layer and a laminated composite semi-circular cantilever shell with discrete cylindrical piezoelectric actuators and/or sensors.

  14. Establishing the Structural Integrity of Core-Shell Nanoparticles against Elemental Migration using Luminescent Lanthanide Probes.

    Science.gov (United States)

    Chen, Bing; Peng, Dengfeng; Chen, Xian; Qiao, Xvsheng; Fan, Xianping; Wang, Feng

    2015-10-19

    Core-shell structured nanoparticles are increasingly used to host luminescent lanthanide ions but the structural integrity of these nanoparticles still lacks sufficient understanding. Herein, we present a new approach to detect the diffusion of dopant ions in core-shell nanostructures using luminescent lanthanide probes whose emission profile and luminescence lifetime are sensitive to the chemical environment. We show that dopant ions in solution-synthesized core-shell nanoparticles are firmly confined in the designed locations. However, annealing at certain temperatures (greater than circa 350 °C) promotes diffusion of the dopant ions and leads to degradation of the integrity of the nanoparticles. These insights into core-shell nanostructures should enhance our ability to understand and use lanthanide-doped luminescent nanoparticles.

  15. On the shape and orientation control of an orbiting shallow spherical shell structure

    Science.gov (United States)

    Bainum, P. M.; Reddy, A. S. S. R.

    1982-01-01

    The dynamics of orbiting shallow flexible spherical shell structures under the influence of control actuators was studied. Control laws are developed to provide both attitude and shape control of the structure. The elastic modal frequencies for the fundamental and lower modes are closely grouped due to the effect of the shell curvature. The shell is gravity stabilized by a spring loaded dumbbell type damper attached at its apex. Control laws are developed based on the pole clustering techniques. Savings in fuel consumption can be realized by using the hybrid shell dumbbell system together with point actuators. It is indicated that instability may result by not including the orbital and first order gravity gradient effects in the plant prior to control law design.

  16. On the shape and orientation control of orbiting shallow spherical shell structure

    Science.gov (United States)

    Bainum, P. M.; Reddy, A. S. S. R.

    1983-01-01

    The dynamics of orbiting shallow flexible spherical shell structures under the influence of control actuators was studied. Control laws are developed to provide both attitude and shape control of the structure. The elastic modal frequencies for the fundamental and lower modes are closely grouped due to the effect of the shell curvature. The shell is gravity stabilized by a spring loaded dumbell type damper attached at its apex. Control laws are developed based on the pole clustering techniques. Savings in fuel consumption can be realized by using the hybrid shell dumbbell system together with point actuators. It is indicated that instability may result by not including the orbital and first order gravity gradient effects in the plant prior to control law design. Previously announced in STAR as N82-17243

  17. Projected shell model study of band structure of 90Nb

    Science.gov (United States)

    Kumar, Amit; Singh, Dhanvir; Gupta, Anuradha; Singh, Suram; Bharti, Arun

    2016-05-01

    A systematic study of two-quasiparticle bands of the odd-odd 90Nb nucleus is performed using the projected shell model approach. Yrast band with some other bands have been obtained and back-bending in moment of inertia has also been calculated and compared with the available experimental. On comparing the available experimental data, it is found that the treatment with PSM provides a satisfactory explanation of the available data.

  18. Polymer-virus core-shell structures prepared via co-assembly and template synthesis methods

    Institute of Scientific and Technical Information of China (English)

    SUTHIWANGCHAROEN; Nisaraporn; PREVELIGE; Peter; E.Jr

    2010-01-01

    Bionanoparticles(BNPs),consisting of virus and virus-like assemblies,have attracted much attention in the biomedical field for their applications such as imaging and targeted drug delivery,owing to their well-defined structures and well-controlled chemistries.BNPs-based core-shell structures provide a unique system for the investigation of biological interactions such as protein-protein and protein-carbohydrate interactions.However,it is still a challenge to prepare the BNPs-based core-shell structures.Herein,we describe(i) co-assembly method and(ii) template synthesis method in the development of polymer-BNPs core-shell structures.These two methods can be divided into three different systems.In system A,different polymers including poly(2-vinylpyridine)(P2VP),poly(4-vinylpyridine)(P4VP) and poly(ε-caprolactone)-block-poly(2-vinylpyridine)(PCL-b-P2VP) can form a raspberry-like structure with BNPs.In system B,polystyrene(PS) spheres end capped with free amine and BNPs can form a core-shell structure.In System C,layer-by-layer(LBL) method is used to prepare positive charged PS particles,which can be used as a template to form the core-shell structures with BNPs.These two methods may open a new way for preparing novel protein-based functional materials for potential applications in the biomedical field.

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

    Science.gov (United States)

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

    2016-05-01

    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.

  20. 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.

  1. Mapping the Atomistic Structure of Graded Core/Shell Colloidal Nanocrystals.

    Science.gov (United States)

    Yarema, Maksym; Xing, Yunhua; Lechner, Rainer T; Ludescher, Lukas; Dordevic, Nikola; Lin, Weyde M M; Yarema, Olesya; Wood, Vanessa

    2017-09-15

    Engineering the compositional gradient for core/shell semiconductor nanocrystals improves their optical properties. To date, however, the structure of graded core/shell nanocrystal emitters has only been qualitatively described. In this paper, we demonstrate an approach to quantify nanocrystal structure, selecting graded Ag-In-Se/ZnSe core/shell nanocrystals as a proof-of-concept material. A combination of multi-energy small-angle X-ray scattering and electron microscopy techniques enables us to establish the radial distribution of ZnSe with sub-nanometer resolution. Using ab initio shape-retrieval analysis of X-ray scattering spectra, we further determine the average shape of nanocrystals. These results allow us to generate three-dimensional, atomistic reconstructions of graded core/shell nanocrystals. We use these reconstructions to calculate solid-state Zn diffusion in the Ag-In-Se nanocrystals and the lattice mismatch between nanocrystal monolayers. Finally, we apply these findings to propose design rules for optimal shell structure and record-luminescent core/shell nanocrystals.

  2. Magnetic field effect on nuclear shell structure and implications to physics of neutron stars

    Energy Technology Data Exchange (ETDEWEB)

    Kondratyev, V.N.; Maruyama, Toshiki; Chiba, Satoshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1999-12-01

    The effect of the magnetic field on the shell structure of nuclei is considered by employing the shell-correction method. The shift of a phase in shell-oscillations is shown to represent the main feature of the field effect. Such a phase-change is originating from the Pauli-magnetic response associated with the relative shift of spin-up and spin-down energy levels. The neutron shell-correction energy behaves almost periodically as a function of the field strength with a slightly enhanced amplitude of the shell-oscillations at a large field. The period of the sign change is determined by the energy difference between neighbour levels. The proton shell-correction energy displays an anomalous dependence on the field. The proton orbital magnetism enhances the nuclear shell effect especially when the field influence is comparable to the spin-orbit coupling. The nuclear magic numbers are demonstrated to depend considerably on the magnetic field on the strength scale B {approx} 10{sup 16} - 10{sup 17} G relevant for neutron stars and supernovas. Such a field is found to shift significantly nuclear magics of the iron region towards smaller mass numbers. (author)

  3. 四种材料治疗牙体楔状缺损的临床疗效观察%Clinical effect on the evaluation of restorations for wedge-shaped defect with four different materials

    Institute of Scientific and Technical Information of China (English)

    倪成励

    2015-01-01

    Objective:To observe and compare late stage clinical effect of fluid resin,light cured composite resin,glass ionomer cement,common glass ionomer on restoration of dental wedge-shaped defects. Methods:Eighty patients with 198 wedge-shaped defect teeth were selected and randomly divided into four groups,with use of Z350 fluid resin( A group ), Z350 light curing resin( B group),Fuji II composite glass ionomer( C group)and FX II glass ionomer( D group)respec-tively for restoration. All the patients were recalled to evaluate the restoration efficacy six months and 12 months later. USA public health service evaluation system modified was used to evaluate the clinical effects of teeth. Results:The success rate of FX II glass ionomer was lower than that in the other three groups at 6 months(P<0. 05). At 12 months,the efficacy of Z350 fluid resin,Fuji II glass ionomer was significantly better than that of the other two groups(P<0. 05). Conclusion:Z350 fluid resin and Fuji II reinforced glass ionomer are ideal materials for the restoration of dental wedge-shaped defects.%目的:观察比较流体树脂、光固化复合树脂、加强型玻璃离子水门汀、普通玻璃离子修复楔状缺损的后期临床效果。方法选择80例病人198颗楔状缺损,随机分为四组,分别使用Z350流体树脂( A组)、Z350光固化树脂( B组)、FujiⅡ复合玻璃离子( C组)和FXⅡ玻璃离子( D组)行充填修复,修复后于6个月、12个月门诊随访,采用改良的美国公共卫生署评价系统对治疗后的患牙进行临床效果评价。结果6个月时FXⅡ玻璃离子的成功率低于其他三组(P<0.05),12个月时,Z350流体树脂、FujiⅡ玻璃离子的疗效均明显优于另外两组(P<0.05)。结论Z350流体树脂和FujiⅡ加强型玻璃离子是修复楔状缺损的理想材料。

  4. 两种斜面修复术治疗楔状缺损临床脱落率疗效观察%Investigation on the expulsion rate of two types of cavities for repairing wedged-shaped defects

    Institute of Scientific and Technical Information of China (English)

    巩蕾; 邱勋定; 郝春波

    2016-01-01

    目的:比较制备短斜面、凹斜面两种洞缘斜配合FiltekA350流体树脂修复楔状缺损后一年内的脱落率。方法收集2011年7月至2012年7月来我科门诊就诊的楔状缺损患者58例,患牙106颗,采用随机数字表将患者随机分为短斜面组和凹斜面组,每组53颗,分别在釉质合面制备短斜面、凹斜面后流体树脂进行充填,观察充填治疗一年内的脱落率。结果凹斜面组与短斜面组患者修复1年内充填体的脱落率分别为4.3%(2/46)和8.0%(4/50),凹斜面组的脱落率低于短斜面组,但差异无统计学意义(P>0.05)。结论凹斜面组配合流体树脂修复楔状缺损,相比短斜面组,修复一年内充填体的脱落率更低。%Objective To investigate the expulsion rate of two restoring methods, the short bevel and the hol-low-ground bevel, using the flowable composite to repair the wedged-shaped defects, within one year after restoring. Methods A total of 58 cases of patients with 106 teeth of wedge-shaped defects, who admitted to Department of Stoma-tology of our hospital from July 2011 to July 2012, were randomly divided into two groups with 53 teeth in each group. After preparing two types of cavities, the short bevel and the hollow-ground bevel, and using the flowable composite to repair the wedged-shaped defects, expulsion rates of two restoring methods during one year after restoring were investi-gated. Results The expulsion rates of the hollow-ground and the short bevel are respectively 8.0% and 4.3%. There was no significant difference between two bevels by using the flowable composite to restore the defect in the expulsion rate. Conclusion Compared with the short bevel, the hollow-ground by using the flowable composite to restore the de-fect has the lower expulsion rate within one year after restoring.

  5. Clinical evaluation of flowable composites in treatment of wedge-shaped defects as a liner%流动复合树脂衬洞在楔状缺损修复中的疗效评价

    Institute of Scientific and Technical Information of China (English)

    李相如; 王静; 李红文

    2011-01-01

    PURPOSE: To evaluate the clinical effects of flowable composite as a liner in treatment of wedge-shaped defects. METHODS: Three hundred and sixty teeth from 85 patients with wedge-shaped defects were studied. The self control design was used in this study. Teelh were randomly divided into experimental group which were restored with composite resin after using flowable composite as a liner in one side, and the control group which were filled with composite resin directly in the other side. The modified USPHS / Ryge criteria were used to evaluate the treatment effects after 1 year and 3 years. SPSS 12.0 software package was used for statistical analysis. RESULTS: There was significant difference between the 2 groups in postoperative sensitivity. The experimental group had higher successful rate than the control group. In marginal integrity, the successful rate of the experimental group was 100% after 1 year, higher than 95.65% in the control group (P<0.01). The successful rate of the experimental group was 98.56% after 3 year, higher than 92.42% in the control group (P<0.01). In postoperative sensitivity: the experimental group had no sensitive cases after 1 year, while the control group had 6 teeth with moderate sensitivity which needed to change the restoration. The experimental group was better than the control group, the difference was statistically significant (P <0.05). CONCLUSION: It can be concluded that flowable composites as a liner in restoration of wedge-shaped defects may improve the marginal integrity and reduce the postoperative sensitivity.%目的:评价流动复合树脂作为洞衬材料在楔状缺损修复中的价值.方法:选择85例患者的360颗楔状缺损患牙为研究对象,采用自身对照设计,随机选择每例患者一侧患牙为实验组,采用流动树脂衬洞后再以复合树脂充填;对侧同名牙为对照组,直接采用复合树脂充填.以改良的USPHS/Ryge临床修复体质量评估系统评价修复后1年和3

  6. Application of gingival retraction cord to the restoration of subgingival wedge-shaped defect%排龈术在龈下楔状缺损修复中的应用研究

    Institute of Scientific and Technical Information of China (English)

    赵静; 葛久禹

    2013-01-01

    Objective To study the clinical performance of gingival retraction cord in repairing subgingival wedge-shaped defects. Methods Totally 40 patients with wedge-shaped defect on both side premolars were selected, one side treated by gingival retraction and filled with composite resin and the other side filled directly with Z350 compos-ite resin. The marginal adaptation,retention and the presence of secondary carries after one year and two years were eval-uated. Results One week after restoration,the incidence of overhanging for dental restoration by using retraction cord to retract gingival was significantly lower than those of the control group(P<0.05). After 1 year and 2 years,the reten-tion of restorations in the control group was significantly lower than that of using retraction cord(P<0.05). Conclusion Gingival retraction cord has high success rate for restoration of subgingival wedge-shaped defect.%目的:评估排龈术对龈下楔状缺损修复效果的影响。方法选择2008年2月至2009年7月来南京大学医学院附属口腔医院牙体牙髓科就诊的双侧上颌前磨牙颈部楔状缺损患者40例,将同一患者的两侧患牙随机分为排龈组与对照组(各40颗牙),排龈组在排龈线排龈后用Z350复合树脂充填,对照组直接用Z350复合树脂充填。随访2年,观察其临床疗效,评价修复体保存、边缘密合性以及继发龋发生情况。结果充填1周后首次复查,排龈组悬突发生率低于对照组,差异有统计学意义(P<0.05)。充填1年和2年后复查,排龈组修复体的脱落率均明显低于对照组,差异有统计学意义(P<0.05)。结论排龈术可提高龈下楔状缺损修复的治疗效果。

  7. 不同方式修复牙齿楔状缺损的疗效对照%Comparison of Therapeutic Effect of Different Ways of Repairing the Wedge-shaped Teeth Defect

    Institute of Scientific and Technical Information of China (English)

    姜蕾

    2013-01-01

      Objective:To observe and compare the clinical curative effect of three kinds of restorations of using glass ionomer cement materials, light curing calcium hydroxide under light cured composite resin materials and light curing calcium hydroxide under light curing resin flow materials. Method:180 cases of patients with canines and 64 cases of patients with premolars tooth wedge-shaped defects who were in need repair were selected and divided into A,B,C 3 groups,each group of 64 teeth,the patients were received the treatment of three kinds of restorations of using glass ionomer cement materials,light curing calcium hydroxide under light cured composite resin materials and light curing calcium hydroxide under light curing resin flow materials respectively. The patients were followed up 6 months after operation and the clinical efficacy were observed.Result:The success rates in A, B,C group of 3 methods for restoring wedge-shaped defect were 81.67%,93.33%and 95.00%after 6 months,of where B,C two group was higher than that in A group and the differences were statistically significant(P0.05). Conclusion:Light curing calcium hydroxide under light cured composite resin materials in treatment of patients with the wedge-shaped teeth dentin exposure has higher repair effect.%  目的:通过应用玻璃离子水门汀材料、光固化氢氧化钙垫底后光固化复合树脂材料及光固化氢氧化钙垫底后光固化流动树脂材料三种不同的楔状缺损修复方式,比较对照这三种修复方式的临床疗效。方法:临床选择180颗尖牙或是前磨牙牙齿楔状缺损需要修复的患者64例,分为A、B、C三组,每组60颗牙齿,分别采用玻璃离子水门汀材料、光固化氢氧化钙垫底后光固化复合树脂材料、光固化氢氧化钙垫底后光固化流动树脂材料三种方法修复楔状缺损,并于术后6个月随访观察疗效。结果:充填后6个月A、B、C组三种方法修复楔状

  8. Numerical modeling of nonlinear deformation and buckling of composite plate-shell structures under pulsed loading

    Science.gov (United States)

    Abrosimov, N. A.

    1999-11-01

    Nonlinear three-dimensional problems of dynamic deformation, buckling, and posteritical behavior of composite shell structures under pulsed loads are analyzed. The structure is assumed to be made of rigidly joined plates and shells of revolution along the lines coinciding with the coordinate directions of the joined elements. Individual structural elements can be made of both composite and conventional isotropic materials. The kinematic model of deformation of the structural elements is based on Timoshenko-type hypotheses. This approach is oriented to the calculation of nonstationary deformation processes in composite structures under small deformations but large displacements and rotation angles, and is implemented in the context of a simplified version of the geometrically nonlinear theory of shells. The physical relations in the composite structural elements are based on the theory of effective moduli for individual layers or for the package as a whole, whereas in the metallic elements this is done in the framework of the theory of plastic flow. The equations of motion of a composite shell structure are derived based on the principle of virtual displacements with some additional conditions allowing for the joint operation of structural elements. To solve the initial boundary-value problem formulated, an efficient numerical method is developed based on the finite-difference discretization of variational equations of motion in space variables and an explicit second-order time-integration scheme. The permissible time-integration step is determined using Neumann's spectral criterion. The above method is especially efficient in calculating thin-walled shells, as well as in the case of local loads acting on the structural element, when the discretization grid has to be condensed in the zones of rapidly changing solutions in space variables. The results of analyzing the nonstationary deformation processes and critical loads are presented for composite and isotropic

  9. Impact of high pCO2 on shell structure of the bivalve Cerastoderma edule.

    Science.gov (United States)

    Milano, Stefania; Schöne, Bernd R; Wang, Schunfeng; Müller, Werner E

    2016-08-01

    Raised atmospheric emissions of carbon dioxide (CO2) result in an increased ocean pCO2 level and decreased carbonate saturation state. Ocean acidification potentially represents a major threat to calcifying organisms, specifically mollusks. The present study focuses on the impact of elevated pCO2 on shell microstructural and mechanical properties of the bivalve Cerastoderma edule. The mollusks were collected from the Baltic Sea and kept in flow-through systems at six different pCO2 levels from 900 μatm (control) to 24,400 μatm. Extreme pCO2 levels were used to determine the effects of potential leaks from the carbon capture and sequestration sites where CO2 is stored in sub-seabed geological formations. Two approaches were combined to determine the effects of the acidified conditions: (1) Shell microstructures and dissolution damage were analyzed using scanning electron microscopy (SEM) and (2) shell hardness was tested using nanoindentation. Microstructures of specimens reared at different pCO2 levels do not show significant changes in their size and shape. Likewise, the increase of pCO2 does not affect shell hardness. However, dissolution of ontogenetically younger portions of the shell becomes more severe with the increase of pCO2. Irrespective of pCO2, strong negative correlations exist between microstructure size and shell mechanics. An additional sample from the North Sea revealed the same microstructural-mechanical interdependency as the shells from the Baltic Sea. Our findings suggest that the skeletal structure of C. edule is not intensely influenced by pCO2 variations. Furthermore, our study indicates that naturally occurring shell mechanical property depends on the shell architecture at μm-scale.

  10. Shell structure and few-nucleon removal in intranuclear cascade

    CERN Document Server

    Mancusi, Davide; Carbonell, Jaume; Cugnon, Joseph; David, Jean-Christophe; Leray, Sylvie

    2014-01-01

    It is well known that intranuclear-cascade models generally overestimate the cross sections for one-proton removal from heavy, stable nuclei by a high-energy proton beam, but they yield reasonable predictions for one-neutron removal from the same nuclei and for one-nucleon removal from light targets. We use simple shell-model calculations to investigate the reasons of this deficiency. We find that a correct description of the neutron skin and of the energy density in the nuclear surface is crucial for the aforementioned observables. Neither ingredient is sufficient if taken separately.

  11. Influence of a Neighboring Charged Group on Hydrophobic Hydration Shell Structure.

    Science.gov (United States)

    Davis, Joel G; Zukowski, Samual R; Rankin, Blake M; Ben-Amotz, Dor

    2015-07-23

    Raman multivariate curve resolution (Raman-MCR), as well as quantum and classical calculations, are used to probe water structural changes in the hydration shells of carboxylic acids and tetraalkyl ammonium ions with various aliphatic chain lengths. The results reveal that water molecules in the hydration shell around the hydrophobic chains undergo a temperature and chain length dependent structural transformation resembling that previously observed in aqueous solutions of n-alcohols. Deprotonation of the carboxylic acid headgroup (at pH ∼ 7) is found to suppress the onset of the hydration-shell structural transformation around the nearest aliphatic methylene group. Tetraalkyl ammonium cations are found to more strongly suppress the water structural transformation, perhaps reflecting the greater intramolecular charge delocalization and suppression of dangling OH defects in water's tetrahedral H-bond network. The observed coupling between ionic and hydrophobic groups, as well as the associated charge asymmetry, may influence the hydrophobicity of proteins and other materials.

  12. 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.

  13. Periodic mesoporous organosilica (PMO) materials with uniform spherical core-shell structure.

    Science.gov (United States)

    Haffer, Stefanie; Tiemann, Michael; Fröba, Michael

    2010-09-10

    We report the synthesis of monodisperse, spherical periodic mesoporous organosilica (PMO) materials. The particles have diameters between about 350 and 550 nm. They exhibit a regular core-shell structure with a solid, non-porous silica core and a mesoporous PMO shell with a thickness of approximately 75 nm and uniform pores of about 1.7 nm. The synthesis of the core and the shell is carried out in a one-pot, two-stage synthesis and can be accomplished at temperatures between 25 and 100 °C. Higher synthesis temperatures lead to substantial shrinking of the solid core, generating an empty void between core and shell. This leads to interesting cavitation phenomena in the nitrogen physisorption analysis at 77.4 K.

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

    Science.gov (United States)

    Deviren, Bayram; Şener, Yunus

    2015-07-01

    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.

  15. Synthesis, structural, optical and photocatalytic properties of CdS/ZnS core/shell nanoparticles

    Science.gov (United States)

    Reddy, Ch. Venkata; Shim, Jaesool; Cho, Migyung

    2017-04-01

    CdS, ZnS and CdS/ZnS core/shell nanoparticles were successfully synthesized via two-step synthesis method. The as-prepared CdS, ZnS and CdS/ZnS core/shell nanoparticles were used to study the structural, morphological, and optical properties by PXRD, TEM, HRTEM, UV-vis spectroscopy, N2 adsorption-desorption, FT-IR, PL and Raman spectroscopy measurements. The XRD pattern confirms the crystal structure of the prepared ZnS, CdS, and CdS/ZnS core/shell nanoparticles. The crystallinity of the as-prepared samples is confirmed by PXRD, TEM and HRTEM analysis. The BET analysis showed that the CdS/ZnS core/shell nanoparticles had larger surface area and pore diameter than CdS and ZnS. The Raman and FT-IR spectra confirm the fundamental vibrational modes of CdS and ZnS respectively. Compared to pure CdS and ZnS, CdS/ZnS core/shell nanoparticles exhibited higher photocatalytic activity for the degradation of methyl orange (MO). The enhancement of photocatalytic activity in the CdS/ZnS core/shell nanoparticles is due to the interface actions between CdS and ZnS, which greatly reduces the recombination of photogenerated electrons-holes pair. The proposed mechanism for degradation of MO dye is discussed in detail.

  16. Structural and magnetic properties of core-shell Au/Fe3O4 nanoparticles

    Science.gov (United States)

    León Félix, L.; Coaquira, J. A. H.; Martínez, M. A. R.; Goya, G. F.; Mantilla, J.; Sousa, M. H.; Valladares, L. De Los Santos; Barnes, C. H. W.; Morais, P. C.

    2017-02-01

    We present a systematic study of core-shell Au/Fe3O4 nanoparticles produced by thermal decomposition under mild conditions. The morphology and crystal structure of the nanoparticles revealed the presence of Au core of d = (6.9 ± 1.0) nm surrounded by Fe3O4 shell with a thickness of ~3.5 nm, epitaxially grown onto the Au core surface. The Au/Fe3O4 core-shell structure was demonstrated by high angle annular dark field scanning transmission electron microscopy analysis. The magnetite shell grown on top of the Au nanoparticle displayed a thermal blocking state at temperatures below TB = 59 K and a relaxed state well above TB. Remarkably, an exchange bias effect was observed when cooling down the samples below room temperature under an external magnetic field. Moreover, the exchange bias field (HEX) started to appear at T~40 K and its value increased by decreasing the temperature. This effect has been assigned to the interaction of spins located in the magnetically disordered regions (in the inner and outer surface of the Fe3O4 shell) and spins located in the ordered region of the Fe3O4 shell.

  17. Core-Shell Structure of a Silicon Nanorod/Carbon Nanotube Field Emission Cathode

    Directory of Open Access Journals (Sweden)

    Bohr-Ran Huang

    2012-01-01

    Full Text Available A novel core-shell structure of silicon nanorods/carbon nanotubes (SiNRs/CNTs is developed for use in field emission cathodes. The CNTs were synthesized on SiNRs, using the Ag-assisted electroless etching technique to form the SiNRs/CNT core-shell structure. This resulting SiNRs/CNT field emission cathode demonstrated improved field emission properties including a lower turn-on electric field on (1.3 V/μm, 1 μA/cm2, a lower threshold electric field th (1.8 V/μm, 1 mA/cm2, and a higher enhancement factor (2347. These superior properties indicate that this core-shell structure of SiNRs/CNTs has good potential in field emission cathode applications.

  18. Shell-based support structures for Nb$_{3}$Sn accelerator quadrupole magnets

    CERN Document Server

    Ferracin, P

    2009-01-01

    Shell-based support structures are being fabricated and tested as part of the development of large-aperture Nb3Sn superconducting quadrupoles for future upgrades of the LHC Interaction Regions. These structures utilize water pressurized bladders for room-temperature pre-load control, and rely on a pre-tensioned aluminum shell to deliver a substantial part of the coil pre-stress during cooldown. The coil final pre-load is therefore monotonically approached from below, without overstressing the strainsensitive conductor. This method has been adopted by the US LARP collaboration to test subscale racetrack coils (SQ series), 1 m long cos-theta coils (TQS series), and 4 m long magnets (LRS and LQS series). We present recent progress in the development of shell-based support structures, with a description of the principles of operations and the future plans.

  19. Thermal Stability of Co-Pt and Co-Au Core-Shell Structured Nanoparticles: Insights from Molecular Dynamics Simulations.

    Science.gov (United States)

    Wen, Yu-Hua; Huang, Rao; Shao, Gui-Fang; Sun, Shi-Gang

    2017-09-07

    Co-Pt and Co-Au core-shell nanoparticles were heated by molecular dynamics simulations to investigate their thermal stability. Two core structures, that is, hcp Co and fcc Co, have been addressed. The results demonstrate that the hcp-fcc phase transition happens in the hcp-Co-core/fcc-Pt-shell nanoparticle, while it is absent in the hcp-Co-core/fcc-Au-shell one. The stacking faults appear in both Pt and Au shells despite different structures of the Co core. The Co core and Pt shell concurrently melt and present an identical melting point in both Co-Pt core-shell nanoparticles. However, typical two-stage melting occurs in both Co-Au core-shell nanoparticles. Furthermore, the Au shell in the hcp-Co-core/fcc-Au-shell nanoparticle exhibits a lower melting point than that in the fcc-Co-core/fcc-Au-shell one, while the melting points are closely equal for both hcp and fcc Co cores. All of these observations suggest that their thermal stability strongly depends on the structure of the core and the element of the shell.

  20. 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.

  1. Evolution of Wurtzite Structured GaAs Shells Around InAs Nanowire Cores

    Directory of Open Access Journals (Sweden)

    Kim Y

    2009-01-01

    Full Text Available Abstract GaAs was radially deposited on InAs nanowires by metal–organic chemical vapor deposition and resultant nanowire heterostructures were characterized by detailed electron microscopy investigations. The GaAs shells have been grown in wurtzite structure, epitaxially on the wurtzite structured InAs nanowire cores. The fundamental reason of structural evolution in terms of material nucleation and interfacial structure is given.

  2. The triple-shell structure and collimated outflows of the planetary nebula NGC 6891

    CERN Document Server

    Guerrero, M; Manchado, A; Vázquez, R A

    1999-01-01

    Narrow-band H$\\alpha$ and [N {\\sc ii}] images and high-dispersion spatially-resolved echelle spectroscopy of the planetary nebula NGC 6891 are presented. These observations show a great wealth of structures. The bright central nebula is surrounded by an attached shell and a detached outer halo. Both the inner and intermediate shells can be described as ellipsoids with similar major to minor axial ratios, but different spatial orientations. The kinematical ages of the intermediate shell and halo are 4,800 and 28,000 years, respectively. The inter-shell time lapse is in good agreement with the evolutionary inter-pulse time lapse. A highly collimated outflow is observed to protrude from the tips of the major axis of the inner nebula and impact on the outer edge of the intermediate shell. Kinematics and excitation of this outflow provide conclusive evidence that it is deflected during the interaction with the outer edge of the intermediate shell. At the same time, both the kinematics and the morphology of the int...

  3. Structural and Magnetic Response in Bimetallic Core/Shell Magnetic Nanoparticles

    Directory of Open Access Journals (Sweden)

    Adeela Nairan

    2016-04-01

    Full Text Available Bimagnetic monodisperse CoFe2O4/Fe3O4 core/shell nanoparticles have been prepared by solution evaporation route. To demonstrate preferential coating of iron oxide onto the surface of ferrite nanoparticles X-ray diffraction (XRD, High resolution transmission electron microscope (HR-TEM and Raman spectroscopy have been performed. XRD analysis using Rietveld refinement technique confirms single phase nanoparticles with average seed size of about 18 nm and thickness of shell is 3 nm, which corroborates with transmission electron microscopy (TEM analysis. Low temperature magnetic hysteresis loops showed interesting behavior. We have observed large coercivity 15.8 kOe at T = 5 K, whereas maximum saturation magnetization (125 emu/g is attained at T = 100 K for CoFe2O4/Fe3O4 core/shell nanoparticles. Saturation magnetization decreases due to structural distortions at the surface of shell below 100 K. Zero field cooled (ZFC and Field cooled (FC plots show that synthesized nanoparticles are ferromagnetic till room temperature and it has been noticed that core/shell sample possess high blocking temperature than Cobalt Ferrite. Results indicate that presence of iron oxide shell significantly increases magnetic parameters as compared to the simple cobalt ferrite.

  4. Shell structure from {sup 100}Sn to {sup 78}Ni: Implications for nuclear astrophysics

    Energy Technology Data Exchange (ETDEWEB)

    Grawe, H.; Gorska, M.; Roeckl, E. [GSI, Darmstadt (Germany); Blazhev, A. [GSI, Darmstadt (Germany); University of Sofia, Sofia (Bulgaria); Mukha, I. [GSI, Darmstadt (Germany); Katholieke Universiteit Leuven, Leuven (Belgium); RRC ' ' Kurchatov Institute' ' , Moscow (Russian Federation); Plettner, C. [GSI, Darmstadt (Germany); Yale University, New Haven, CT (United States); Nowacki, F. [IReS, Strasbourg, Cedex (France); Grzywacz, R. [ORNL, Oak Ridge, TN (United States); Sawicka, M. [IEP Warsaw University, Warsaw (Poland)

    2005-09-01

    The single-particle structure and shell gap of {sup 100}Sn is inferred from prompt in-beam and delayed {gamma}-ray spectroscopy of seniority and spin-gap isomers. Recent results in {sup 94,95}Ag and {sup 98}Cd stress the importance of large-scale shell model calculations employing realistic interactions for the isomerism, np-nh excitations and E2 polarisation of the {sup 100}Sn core. The strong monopole interaction of the {delta}l=0 spin-flip partners {pi}g{sub 9/2}-{nu}g{sub 7/2} in N=51 isotones below {sup 100}Sn is echoed in the {delta}l=1 {pi}f{sub 5/2}- {nu}g{sub 9/2} pair of nucleons, which is decisive for the persistence of the N=50 shell gap in {sup 78}Ni. This is corroborated by recent experimental data on {sup 70,} {sup 76}Ni, {sup 78}Zn. The importance of monopole driven shell evolution for the appearance of new shell closures in neutron-rich nuclei and implications for r-process abundances near the N=82 shell is discussed. (orig.)

  5. Photoluminescence and structural properties of Si/SiC core–shell nanowires growth by HWCVD

    Energy Technology Data Exchange (ETDEWEB)

    Nazarudin, Nur Fatin Farhanah Binti; Mohd Noor, Nurul Jannah Binti; Rahman, Saadah Abdul; Goh, Boon Tong, E-mail: boontong77@yahoo.com

    2015-01-15

    Si/SiC core–shell nanowires grown by hot-wire chemical vapor deposition were studied. Ni nanoparticles act as metal nano-templates to catalyze the growth of these core–shell nanowires. These nanowires were grown at different deposition pressures of 0.5 and 1 mbar. The nanowires showed a tapered-like morphology at deposition pressure 0.5 mbar. Increase in pressure to 1 mbar leads to a formation of agglomerated grains at the root of the nanowires. The results show that these nanowires consisted of crystalline Si core and amorphous SiC shell nanowires. Increase in pressure enhanced the formation of SiC phase in the shell of the nanowires. On the other hand, the formation of the agglomerated grains attributed to an increasing of the SiC phase at higher deposition pressure. The presence of Si and SiC nano-crystallites embedded within an amorphous matrix exhibited a room temperature PL emission in the range of 400–1000 nm. The effects of the deposition pressure on the optical and structural properties of the nanowires are also discussed. - Highlights: • Growth of Si/SiC core–shell nanowires by HWCVD. • The nanowires consisted of crystalline Si core and amorphous SiC shell. • Metal nano-templates catalyzed the growth of Si core nanowires. • Increase in deposition pressure enhanced the SiC phase. • The presence of nano-crystallites exhibited a room temperature PL.

  6. Structural and Magnetic Response in Bimetallic Core/Shell Magnetic Nanoparticles

    Science.gov (United States)

    Nairan, Adeela; Khan, Usman; Iqbal, Munawar; Khan, Maaz; Javed, Khalid; Riaz, Saira; Naseem, Shahzad; Han, Xiufeng

    2016-01-01

    Bimagnetic monodisperse CoFe2O4/Fe3O4 core/shell nanoparticles have been prepared by solution evaporation route. To demonstrate preferential coating of iron oxide onto the surface of ferrite nanoparticles X-ray diffraction (XRD), High resolution transmission electron microscope (HR-TEM) and Raman spectroscopy have been performed. XRD analysis using Rietveld refinement technique confirms single phase nanoparticles with average seed size of about 18 nm and thickness of shell is 3 nm, which corroborates with transmission electron microscopy (TEM) analysis. Low temperature magnetic hysteresis loops showed interesting behavior. We have observed large coercivity 15.8 kOe at T = 5 K, whereas maximum saturation magnetization (125 emu/g) is attained at T = 100 K for CoFe2O4/Fe3O4 core/shell nanoparticles. Saturation magnetization decreases due to structural distortions at the surface of shell below 100 K. Zero field cooled (ZFC) and Field cooled (FC) plots show that synthesized nanoparticles are ferromagnetic till room temperature and it has been noticed that core/shell sample possess high blocking temperature than Cobalt Ferrite. Results indicate that presence of iron oxide shell significantly increases magnetic parameters as compared to the simple cobalt ferrite.

  7. Lifting shell structures in the dynamically assisted Schwinger effect in periodic fields

    CERN Document Server

    Otto, Andreas; Blaschke, David; Kampfer, Burkhard; Smolyansky, Stanislav Alexandrovich

    2015-01-01

    The dynamically assisted pair creation (Schwinger effect) is considered for the superposition of two periodic electric fields acting a finite time interval. We find a strong enhancement by orders of magnitude caused by a weak field with a frequency being a multitude of the strong-field frequency. The strong low-frequency field leads to shell structures which are lifted by the weaker high-frequency field. The resonance type amplification refers to a new, monotonously increasing mode, often hidden in some strong oscillatory transient background which disappears during the smoothly switching off the background fields, thus leaving a pronounced residual shell structure in phase space.

  8. On the vibration of double-walled carbon nanotubes using molecular structural and cylindrical shell models

    Science.gov (United States)

    Ansari, R.; Rouhi, S.; Aryayi, M.

    2016-01-01

    The vibrational behavior of double-walled carbon nanotubes is studied by the use of the molecular structural and cylindrical shell models. The spring elements are employed to model the van der Waals interaction. The effects of different parameters such as geometry, chirality, atomic structure and end constraint on the vibration of nanotubes are investigated. Besides, the results of two aforementioned approaches are compared. It is indicated that by increasing the nanotube side length and radius, the computationally efficient cylindrical shell model gives rational results.

  9. Lifting shell structures in the dynamically assisted Schwinger effect in periodic fields

    Directory of Open Access Journals (Sweden)

    A. Otto

    2015-01-01

    Full Text Available The dynamically assisted pair creation (Schwinger effect is considered for the superposition of two periodic electric fields acting in a finite time interval. We find a strong enhancement by orders of magnitude caused by a weak field with a frequency being a multitude of the strong-field frequency. The strong low-frequency field leads to shell structures which are lifted by the weaker high-frequency field. The resonance type amplification refers to a new, monotonously increasing mode, often hidden in some strong oscillatory transient background, which disappears during the smoothly switching off the background fields, thus leaving a pronounced residual shell structure in phase space.

  10. Preparation of Hollow Spherical and Core/shell Structured Powders by Plasma Processing

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Xiaofeng; ZHOU; Kesong; DENG; Changguang; SONG; Jinbing; ZHANG; Jifu; DONG; Shujuan

    2015-01-01

    Four types of hollow spherical micro- and nano-szied powders of ZrO2-7wt.%Y2O3(7YSZ), ZrO2-7wt.%Y2O3, Al2O3-13 wt.% TiO2(AT) and WC as well as one type of core/shell structured powder of ZrB2-30 wt.%Mo Si2 were prepared via plasma processing. In addition, the formation mechanisms of hollow spherical and core/shell structured powders prepared via plasma processing were also proposed.

  11. Lifting shell structures in the dynamically assisted Schwinger effect in periodic fields

    Energy Technology Data Exchange (ETDEWEB)

    Otto, A., E-mail: a.otto@hzdr.de [Institute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden (Germany); Institut für Theoretische Physik, Technische Universität Dresden, Zellescher Weg 17, 01062 Dresden (Germany); Seipt, D. [Helmholtz-Institut Jena, Fröbelstieg 3, 07743 Jena (Germany); Blaschke, D. [Group of Elementary Particle Theory, Institute for Theoretical Physics, University of Wroclaw, pl. M. Borna 9, 50-204 Wroclaw (Poland); Kämpfer, B. [Institute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden (Germany); Institut für Theoretische Physik, Technische Universität Dresden, Zellescher Weg 17, 01062 Dresden (Germany); Smolyansky, S.A. [Department of Physics, Saratov State University, 410071 Saratov (Russian Federation)

    2015-01-05

    The dynamically assisted pair creation (Schwinger effect) is considered for the superposition of two periodic electric fields acting in a finite time interval. We find a strong enhancement by orders of magnitude caused by a weak field with a frequency being a multitude of the strong-field frequency. The strong low-frequency field leads to shell structures which are lifted by the weaker high-frequency field. The resonance type amplification refers to a new, monotonously increasing mode, often hidden in some strong oscillatory transient background, which disappears during the smoothly switching off the background fields, thus leaving a pronounced residual shell structure in phase space.

  12. Structural instability of shell-like assemblies of a keplerate-type polyoxometalate induced by ionic strength.

    Science.gov (United States)

    Veen, Sandra J; Kegel, Willem K

    2009-11-19

    We demonstrate a new structural instability of shell-like assemblies of polyoxometalates. Besides the colloidal instability, that is, the formation of aggregates that consist of many single layered POM-shells, these systems also display an instability on a structural scale within the shell-like assemblies. This instability occurs at significantly lower ionic strength than the colloidal stability limit and only becomes evident after a relatively long time. For the polyoxometalate, abbreviated as {Mo(72)Fe(30)}, it is shown that the structural stability limit of POM-shells lies between a NaCl concentration of 1.00 and 5.00 mM in aqueous solution.

  13. Validity boundary of orbital-free molecular dynamics method corresponding to thermal ionization of shell structure

    Science.gov (United States)

    Gao, Chang; Zhang, Shen; Kang, Wei; Wang, Cong; Zhang, Ping; He, X. T.

    2016-11-01

    With 6LiD as an example, we show that the applicable region of the orbital-free molecular dynamics (OFMD) method in a large temperature range is determined by the thermal ionization process of bound electrons in shell structures. The validity boundary of the OFMD method is defined roughly by the balance point of the average thermal energy of an electron and the ionization energy of the lowest localized electronic state. This theoretical proposition is based on the observation that the deviation of the OFMD method originates from its less accurate description to the charge density in partially ionized shells, as compared with the results of the extended first-principles molecular dynamics method, which well reproduces the charge density of shell structures.

  14. 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.

  15. Material and Geometric Nonlinear Analysis of Functionally Graded Plate-Shell Type Structures

    Science.gov (United States)

    Moita, J. S.; Araújo, A. L.; Mota Soares, C. M.; Mota Soares, C. A.; Herskovits, J.

    2016-08-01

    A nonlinear formulation for general Functionally Graded Material plate-shell type structures is presented. The formulation accounts for geometric and material nonlinear behaviour of these structures. Using the Newton-Raphson incremental-iterative method, the incremental equilibrium path is obtained, and in case of snap-through occurrence the automatic arc-length method is used. This simple and fast element model is a non-conforming triangular flat plate/shell element with 24 degrees of freedom for the generalized displacements. It is benchmarked in the solution of some illustrative plate- shell examples and the results are presented and discussed with numerical alternative models. Benchmark tests with material and geometrically nonlinear behaviour are also proposed.

  16. Study of CRFP Shell Structures under Dynamic Loading in Shock Tube Setup

    Directory of Open Access Journals (Sweden)

    H. A. Khawaja

    2014-01-01

    Full Text Available The paper gives the study of the response of carbon fiber reinforced polymers (CRFP quasi-isotropic shell structures under the influence of dynamic loading. The quasi-isotropic CRFP shell specimens are fabricated using Multipreg E720 laminates. These laminates are laid in such a way that shell structure has equal strength and mechanical properties in the two-dimensional (2D plane and hence can be regarded as quasi-isotropic. In this study, the dynamic loading is generated using shock waves in a shock tube experimental setup. The strain and pressure data is collected from the experiments. Additional tests are carried out using Material Test System (MTS for both tensile and flexural response of CRFP. Results obtained from experiments are compared with numerical simulations using ANSYS Multiphysics 14.0 finite element method (FEM package. The numerical simulation and experimental results are found to be in good agreement.

  17. Structural characterization of Pt-Pd core-shell nanoparticles by Cs-corrected STEM

    Energy Technology Data Exchange (ETDEWEB)

    Esparza, R., E-mail: resparza@fata.unam.mx [Universidad Nacional Autonoma de Mexico, Centro de Fisica Aplicada y Tecnologia Avanzada (Mexico); Garcia-Ruiz, Amado F. [UPIICSA-COFAA, Instituto Politecnico Nacional (Mexico); Velazquez Salazar, J. J. [University of Texas at San Antonio, Department of Physics and Astronomy (United States); Perez, R. [Universidad Nacional Autonoma de Mexico, Centro de Fisica Aplicada y Tecnologia Avanzada (Mexico); Jose-Yacaman, M. [The University of Texas at San Antonio, Department of Physics and Astronomy (United States)

    2013-01-15

    Pt-Pd core-shell nanoparticles were synthesized using a modified polyol method. A thermal method under refluxing, carrying on the reaction up to 285 Degree-Sign C, has been performed to reduce metallic salts using ethylene glycol as reducer and poly(N-vinyl-2-pyrrolidone) as protective reagent of the formed bimetallic nanoparticles. According to other works, this type of structure has been studied and utilized to successfully increase the catalytic properties of monometallic nanoparticles Pt or Pd. Core-shell bimetallic nanoparticles were structurally characterized using aberration-corrected scanning transmission electron microscopy (Cs-STEM) equipped with a high-angle annular dark field detector, energy-dispersive X-ray spectrometry (EDS), and electron energy-loss spectroscopy (EELS). The high-resolution elemental line scan and mappings were carried out using a combination of STEM-EDS and STEM-EELS. The obtained results show the growth of the Pd shell on the Pt core with polyhedral morphology. The average size of the bimetallic nanoparticles was 13.5 nm and the average size of the core was 8.5 nm; consequently, the thickness of the shell was around 2.5 nm. The growth of the Pd shell on the Pt core is layer by layer, suggesting a Frank-van der Merwe growth mechanism.

  18. Numerical analysis of stiffened shells of revolution. Volume 3: Users' manual for STARS-2B, 2V, shell theory automated for rotational structures, 2 (buckling, vibrations), digital computer programs

    Science.gov (United States)

    Svalbonas, V.

    1973-01-01

    The User's manual for the shell theory automated for rotational structures (STARS) 2B and 2V (buckling, vibrations) is presented. Several features of the program are: (1) arbitrary branching of the shell meridians, (2) arbitrary boundary conditions, (3) minimum input requirements to describe a complex, practical shell of revolution structure, and (4) accurate analysis capability using a minimum number of degrees of freedom.

  19. The effects of laterally varying icy shell structure on the tidal response of Europa and Ganymede

    Science.gov (United States)

    Wahr, J. M.; A, G.; Zhong, S.

    2013-12-01

    One of the long-sought objectives of an icy moon orbiter or fly-by mission, has been to use tidal observations to help determine the existence of a liquid ocean and characteristics of the overlying icy shell. The radio science component of such a mission could be used to estimate the tidal potential Love number k2 for gravity. And if there is an on-board laser altimeter, it could be used to determine the radial displacement Love number h2. Knowledge of either of those Love numbers could provide information on the presence of an ocean beneath the icy outer shell, and the two Love numbers could be combined to place constraints on the thickness of the icy shell. Though if a subsurface ocean exists, complications could conceivably arise if the icy outer shell has significant lateral variations in elastic thickness or shear modulus, or if the ocean is not global in extent so that the icy shell is grounded in places but floating in others. In these cases, the tidal deformation pattern would not be represented as the sum of degree 2 harmonics, and so the results could not be characterized in terms of a single Love number. In this study, by solving a set of tidal loading problems with laterally variable icy shell structures (for which the existence of an ocean layer is assumed), we investigate how those structures might complicate the interpretation of the tide measurements, and we discuss how to extract information regarding the interior structure of Ganymede and Europa from measurements of their tidal response.

  20. Neutron Halo and Nuclear Shell Structure in New Nuclide 31Ne

    Institute of Scientific and Technical Information of China (English)

    REN ZhongZhou; CHEN BaoQiu; MA ZhongYu; XU GongOu

    2001-01-01

    The ground state properties of new nuclide 31Ne are investigated within the framework of the densitydependent relativistic mean-field theory. One-neutron halo in 31Ne is predicted. Calculations also show that the ground state of31Ne is (3/2)- and it can be used for the testing of the nuclear shell structure near the neutron-drip line.``

  1. Ultrafast structural and vibrational dynamics of the hydration shell around DNA

    Directory of Open Access Journals (Sweden)

    Szyc Ł

    2013-03-01

    Full Text Available Two-dimensional infrared spectroscopy in the frequency range of OH- and NH stretch excitations serves for a direct mapping of hydration dynamics around DNA. A moderate slowing down of structural dynamics and resonant OH stretch energy transfer is observed in the DNA water shell compared to bulk water.

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

    DEFF Research Database (Denmark)

    Sørensen, Rene; Lund, Erik

    2012-01-01

    be performed on the basis of different materials, and/or consist of discrete selection of the same orthotropic material with different orientations of the fibers. The problem considered is the optimization of a general laminated composite shell structure with respect to maximum stiffness (minimum compliance...

  3. Exploring the changing of shell structure of nuclei at N=50

    Energy Technology Data Exchange (ETDEWEB)

    De Angelis, G. [Istituto Nazionale di Fisica Nucleare laboratori Nazionali di Legnaro, Legnaro (Italy); Duchene, G.; Faul, T. [IPHC, IN2P3/CNRS et Universite' Louis Pasteur, Strasbourg, (France)] (and others)

    2005-07-01

    Here it is reported an experimental study of the excited structures of the neutron-rich N=50 and 51 isotones. New experimental information has been obtained on a wide range of nuclei close to the N=50 shell closure by means of multi-nucleon transfer and deep-inelastic collisions. The reaction mechanism allows the population of medium and high-spin yrast states. The systematic of the N=51 single-neutron states, extended down to the Z=34, can be used to test the predictions of the shell evolution based on the effects of the tensor interactions as well as of the different effective interactions.

  4. Diffractive imaging of transient electronic core-shell structures in a nanoplasma

    CERN Document Server

    Rupp, Daniela; Adolph, Marcus; Gorkhover, Tais; Krikunova, Maria; Müller, Jan-Phillipe; Müller, Maria; Oelze, Tim; Ovcharenko, Yevheniy; Sauppe, Mario; Schorb, Sebastian; Wolter, David; Harmand, Marion; Treusch, Rolf; Bostedt, Christoph; Möller, Thomas

    2016-01-01

    We have recorded the coherent diffraction images of individual xenon clusters using intense extreme ultraviolet free-electron laser pulses tuned to atomic and ionic resonances in order to elucidate the influence of light induced electronic changes on the diffraction pattern. The data show the emergence of a transient core-shell structure within the otherwise homogeneous sample. Simulations indicate that ionization and nanoplasma formation result in a cluster shell with strongly altered refraction. The presented resonant scattering approach enables the imaging of ultrafast electron dynamics with unprecedented spatial resolution on their natural time scale.

  5. AN EXACT ANALYSIS FOR FREE VIBRATION OF A COMPOSITE SHELL STRUCTURE- HERMETIC CAPSULE

    Institute of Scientific and Technical Information of China (English)

    尚新春

    2001-01-01

    An exact analytical solution was presented for free vibration of composite shell structure-hermetic capsule. The basic equations on axisymmetric vibration were based on the Love classical thin shell theory and derived for shells of revolution with arbitrary meridian shape. The conditions of the junction between the spherical and the cylindrical shell segments are given by the continuity of deformation and the equilibrium relations near the junction point. The mathematical model of problem is reduced to as an eigenvalue problem for a system of ordinary differential equations in two separate domains corresponding to the spherical and the cylindrical shell segments. By using Legendre and trigonometric functions, exact and explicitly analytical solutions of the mode functions were constructed and the exact frequency equation were obtained. The implementation of Maple programme indicates that all calculations are simple and efficient in both the exact symbolic calculation and the numerical results of natural frequencies compare with the results using finite element methods and other numerical methdos. As a benchmark, the exactly analytical solutions presented in this paper is valuable to examine the accuracy of various approximate methods.

  6. 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.

  7. Strain-induced structural defects and their effects on the electrochemical performances of silicon core/germanium shell nanowire heterostructures.

    Science.gov (United States)

    Lin, Yung-Chen; Kim, Dongheun; Li, Zhen; Nguyen, Binh-Minh; Li, Nan; Zhang, Shixiong; Yoo, Jinkyoung

    2017-01-19

    We report on strain-induced structural defect formation in core Si nanowires of a Si/Ge core/shell nanowire heterostructure and the influence of the structural defects on the electrochemical performances in lithium-ion battery anodes based on Si/Ge core/shell nanowire heterostructures. The induced structural defects consisting of stacking faults and dislocations in the core Si nanowire were observed for the first time. The generation of stacking faults in the Si/Ge core/shell nanowire heterostructure is observed to prefer settling in either only the Ge shell region or in both the Ge shell and Si core regions and is associated with the increase of the shell volume fraction. The relaxation of the misfit strain in the [112] oriented core/shell nanowire heterostructure leads to subsequent gliding of Shockley partial dislocations, preferentially forming the twins. The observation of crossover of defect formation is of great importance for understanding heteroepitaxy in radial heterostructures at the nanoscale and for building three dimensional heterostructures for the various applications. Furthermore, the effect of the defect formation on the nanomaterial's functionality is investigated using electrochemical performance tests. The Si/Ge core/shell nanowire heterostructures enhance the gravimetric capacity of lithium ion battery anodes under fast charging/discharging rates compared to Si nanowires. However, the induced structural defects hamper lithiation of the Si/Ge core/shell nanowire heterostructure.

  8. Corrugated Shell Displacements During the Passage of a Vehicle Along a Soil-Steel Structure

    Science.gov (United States)

    Machelski, Czesław; Mumot, Marcin

    2016-12-01

    Corrugated steel plates are highly rigid and as the constructions can be immersed in soil, they can be used as soil-steel structures. With an increase of cover depth, the effectiveness of operating loads decreases. A substantial reduction of the impacts of vehicles takes place as a road or rail surface with its substructure is crucial. The scope of load's impact greatly exceeds the span L of a shell. This article presents the analysis of deformations of the upper part of a shell caused by a live load. One of the assumptions used in calculations performed in Plaxis software was the circle-shaped shell and the circumferential segment of the building structure in the 2D model. The influence lines of the components of vertical and horizontal displacements of points located at the highest place on the shell were used as a basis of analysis. These results are helpful in assessing the results of measurements carried out for the railway structure during the passage of two locomotives along the track. This type of load is characterized by a steady pressure onto wheels with a regular wheel base. The results of measurements confirmed the regularity of displacement changes during the passage of this load.

  9. 不同排龈方法修复龈下楔状缺损的远期疗效观察%The long-term theraputic effect of different gingival retraction techniques on subgingival wedge-shaped defect

    Institute of Scientific and Technical Information of China (English)

    林萤; 杨春丽

    2013-01-01

    [ABSTRACT] Objective: To evaluate the long-term theraputic effect of different gingival retraction techniques on subgingival wedge-shaped defect. Methods: 78 patients(297 teeth) with wedge-shaped defects were selected and divided into two groups: 43 patients(155 teeth) in gingival retraction code group were restored with the aid of gingival retraction code, 35 patients(142 teeth) in gingival retractor group were restored with the aid of LM gingival retractor. Al the defects were filed with Clearfil SE Bond system and 3M Z250 composite resin. Al cases were folowed up for 1 year. The results were evaluated by modified USPHS criteria including retention, marginal adaptation, recurrent caries, marginal discolor, new defect, gingival response and pulp response. Retention rate and successful rate were compared between the two groups. Results: 100% retention rate was recorded in the two groups. The one-year successful rates were 98.06 and 97.89% respectively, without significant difference between the two groups(p > 0.05). Conclusions: Subgingival defects can be satisfactorily restored with the aid of effective gingival retraction techniques, without difference between gingival retraction code and LM gingival retractor.%  目的对比观察排龈线和推龈器两种排龈方法修复龈下楔状缺损的远期疗效。方法纳入2011年4月至2011年12月间本院口腔科收治的龈下楔状缺损患者78例,共297颗缺损位于龈下0~2mm 内的患牙。根据修复前不同排龈方法将所有患者分为两组:排龈线组43例155颗患牙填充前使用排龈线排龈,推龈器组35例142颗患牙填充前使用推龈器排龈。两组均使用可乐丽菲露自酸蚀粘接剂粘接,3M Z250树脂进行充填。随访1年,以改良的美国公共健康署制定的 USPHS 直接临床评估系统评估远期疗效。结果楔状缺损修复1年后复查,两组患牙充填体均无脱落。通过对患牙修复体脱落情况、边缘密合度、

  10. Er:YAG 激光治疗楔形缺损的临床观察%Clinical evaluation of the effects of Er:YAG laser in the treatment of cervical wedge -shaped defects

    Institute of Scientific and Technical Information of China (English)

    杨文东; 赵继志; 王鑫; 马林; 李倩; 李珍; 张洁; 郭春岚; 吴宣; 蔡文

    2016-01-01

    目的:比较传统旋转器械和 Er:YAG 激光治疗楔形缺损过程中患者的主观感受及树脂充填后的远期临床疗效。方法:选择35~68岁口内同颌对称性且程度相似的楔形缺损患者26例共104个患牙,采用自身对照法,随机选取一侧作为对照组,机械预备窝洞;另一侧实验组用 Er:YAG 激光预备窝洞。采用自酸蚀粘结技术,3M复合树脂充填。术后即刻填写调查问卷,对两种方法的疼痛、气味、噪音、恐惧程度及患者的接受程度进行评估,术后1年采用改良的评定系统 USPHS 对充填体进行临床评价。结果:治疗后即刻问卷调查结果显示:22/26位患者(85%)认为激光备洞较机械备洞疼痛和不适感轻,在下次治疗时更愿意优先选择激光;4/26的患者认为两种治疗方法差别不大。术后1年 26例患者中失访2例,其余24例共98个牙复查结果显示:实验组和对照组总有效率分别为86%和88%(P >0.05)。结论:Er:YAG 激光在窝洞预备过程中患者感觉更舒适,修复体粘结效果与机械预备相当。%AIM:To compare the effects of traditional rotary instrument and Er:YAG laser in the treatment of cervical wedge -shaped defects.METHODS:1 04 teeh of 26 patients with similar degree of cervical wedge -shaped lesions symmetrically in the same jaw were included.The teeth on one side were randomly selected for cavity preparation by Er:YAG laser as experiment group.Those in other side prepared by traditional rotary bur as the con-trol.Cavities were filled with 3Mcomposite resin by self etching adhesive technique.The patients were investigated by a questionnaire about pain,smell,noise,fear and preferred method for next cavity preparation.All restorations were followed up for 1 year after treatment by USPHS criteria.RESULTS:24 patients with 98 teeth finished the follow up. The questionnaire survey showed that 22 /26 patients(85%)preferred Er

  11. One-dimensional photonic bandgap structure in abalone shell

    Institute of Scientific and Technical Information of China (English)

    LI Bo; ZHOU Ji; LI Longtu; LI Qi; HAN Shuo; HAO Zhibiao

    2005-01-01

    @@ Photonic bandgap (PBG) materials are periodic com- posites of dielectric materials in which electromagnetic waves of certain frequency range cannot propagate in any or a special direction. Recently, there has been great inter- est in synthetic PBG materials due to their ability in ma- nipulation of photons. Since 500 million years ago, the natural world has been exploiting photonic structures for specific biological purposes[1]. Different types of biologi- cal PBG materials have been discovered in recent years, such as the one-dimension PBG structure in the sea mouse Aphrodita[2], and the fruits Elaeocarpus[3,4]; two-dimension PBG structure in the male peacock Pavo muticus feathers[5], Indonesian male Papilio palinurus butterfly[6], Thaumantis diores butterfly[7] and the male Ancyluris meliboeus Fabricius butterflies[8]; and three-dimension PBG structure in the weevil Pachyrhynchus argus[9].

  12. High performance carbon nanotube-Si core-shell wires with a rationally structured core for lithium ion battery anodes.

    Science.gov (United States)

    Fan, Yu; Zhang, Qing; Lu, Congxiang; Xiao, Qizhen; Wang, Xinghui; Tay, Beng Kang

    2013-02-21

    Core-shell Si nanowires are very promising anode materials. Here, we synthesize vertically aligned carbon nanotubes (CNTs) with relatively large diameters and large inter-wire spacing as core wires and demonstrate a CNT-Si core-shell wire composite as a lithium ion battery (LIB) anode. Owing to the rationally engineered core structure, the composite shows good capacity retention and rate performance. The excellent performance is superior to most core-shell nanowires previously reported.

  13. The structure of mollusc larval shells formed in the presence of the chitin synthase inhibitor Nikkomycin Z

    Directory of Open Access Journals (Sweden)

    Weiss Ingrid M

    2007-11-01

    Full Text Available Abstract Background Chitin self-assembly provides a dynamic extracellular biomineralization interface. The insoluble matrix of larval shells of the marine bivalve mollusc Mytilus galloprovincialis consists of chitinous material that is distributed and structured in relation to characteristic shell features. Mollusc shell chitin is synthesized via a complex transmembrane chitin synthase with an intracellular myosin motor domain. Results Enzymatic mollusc chitin synthesis was investigated in vivo by using the small-molecule drug NikkomycinZ, a structural analogue to the sugar donor substrate UDP-N-acetyl-D-glucosamine (UDP-GlcNAc. The impact on mollusc shell formation was analyzed by binocular microscopy, polarized light video microscopy in vivo, and scanning electron microscopy data obtained from shell material formed in the presence of NikkomycinZ. The partial inhibition of chitin synthesis in vivo during larval development by NikkomycinZ (5 μM – 10 μM dramatically alters the structure and thus the functionality of the larval shell at various growth fronts, such as the bivalve hinge and the shell's edges. Conclusion Provided that NikkomycinZ mainly affects chitin synthesis in molluscs, the presented data suggest that the mollusc chitin synthase fulfils an important enzymatic role in the coordinated formation of larval bivalve shells. It can be speculated that chitin synthesis bears the potential to contribute via signal transduction pathways to the implementation of hierarchical patterns into chitin mineral-composites such as prismatic, nacre, and crossed-lamellar shell types.

  14. Site-specific carbon deposition for hierarchically ordered core/shell-structured graphitic carbon with remarkable electrochemical performance.

    Science.gov (United States)

    Lv, Yingying; Wu, Zhangxiong; Qian, Xufang; Fang, Yin; Feng, Dan; Xia, Yongyao; Tu, Bo; Zhao, Dongyuan

    2013-10-01

    A fascinating core-shell-structured graphitic carbon material composed of ordered microporous core and uniform mesoporous shell is fabricated for the first time through a site-specific chemical vapor deposition process by using a nanozeolite@mesostructured silica composite molecular sieve as the template. The mesostructure-directing agent cetyltrimethylammonium bromide in the shell of the template can be either burned off or carbonized so that it is successfully utilized as a pore switch to turn the shell of the template "on" or "off" to allow selective carbon deposition. The preferred carbon deposition process can be performed only in the inner microporous zeolite cores or just within the outer mesoporous shells, resulting in a zeolite-like ordered microporous carbon or a hollow mesoporous carbon. Full carbon deposition in the template leads to the new core-shell-structured microporous@mesoporous carbon with a nanographene-constructed framework for fast electron transport, a microporous nanocore with large surface area for high-capacity storage of lithium ions, a mesoporous shell with highly opened mesopores as a transport layer for lithium ions and electron channels to access inner cores. The ordered micropores are protected by the mesoporous shell, avoiding pore blockage as the formation of solid electrolyte interphase layers. Such a unique core-shell-structured microporous@mesoporous carbon material represents a newly established lithium ion storage model, demonstrating high reversible energy storage, excellent rate capability, and long cyclic stability.

  15. Design of a new toroidal shell and support structure for RFX

    Energy Technology Data Exchange (ETDEWEB)

    Baker, W.; Dal Bello, S. E-mail: dalbello@igi.pd.cnr.it; Marcuzzi, D.; Sonato, P.; Zaccaria, P

    2002-12-01

    The physics results obtained from RFP experiments at high current (0.8-1 MA) indicate the need for a better control of the plasma MHD modes, which grow rapidly and lock to the wall during the pulse. The modifications planned for the RFX machine have been designed to guarantee both a passive and an active control of these modes. The present 65 mm thick aluminium shell will be replaced by a 3 mm thick copper shell which is assembled on the vacuum vessel, closer to the plasma edge. In addition 192 saddle coils will be installed to actively control the main mode spectrum of RFX. As a result of these modifications, a new toroidal support structure will be required, which carries out the mechanical functions of the previous shell and supports the new saddle coils. This paper deals with the design of the thin shell and toroidal structure. The solutions which guarantee the required safety level, from a mechanical and thermal point of view, and the technological details of the electrical insulation systems for the various components are highlighted.

  16. Core/shell structured iron/iron-oxide nanoparticles as excellent MRI contrast enhancement agents

    Energy Technology Data Exchange (ETDEWEB)

    Khurshid, Hafsa, E-mail: hkhurshi@udel.edu [Department of Physics and Astronomy, University of Delaware, 217 sharp lab, Newark, DE 19716 (United States); Hadjipanayis, Costas G. [Department of Neurological Surgery, Emory University School of Medicine Atlanta, GA 30322 (United States); Chen, Hongwei [Department of Radiology, Emory University School of Medicine Atlanta, GA 30322 (United States); Li, Wanfeng [Department of Physics and Astronomy, University of Delaware, 217 sharp lab, Newark, DE 19716 (United States); Mao, Hui [Department of Radiology, Emory University School of Medicine Atlanta, GA 30322 (United States); Machaidze, Revaz [Department of Neurological Surgery, Emory University School of Medicine Atlanta, GA 30322 (United States); Tzitzios, Vasilis [Institute of Materials Science, “Demokritos” 15310 Athens (Greece); Hadjipanayis, George C. [Department of Physics and Astronomy, University of Delaware, 217 sharp lab, Newark, DE 19716 (United States)

    2013-04-15

    We report the use of metallic iron-based nanoparticles for magnetic resonance imaging (MRI) applications. Core/shell structured iron-based nanoparticles prepared by thermally decomposing organo-metallic compounds of iron at high temperature in the presence of hydrophobic surfactants were coated and stabilized in the aqueous solvent using the newly developed polysiloxane PEO–b–PγMPS (poly(ethylene oxide)–block–poly (γ methacryloxypropyl trimethyl oxysilane)) diblock copolymers. Particles are well suspended in water and retain their core–shell morphology after coating with the copolymer. In comparison to the conventionally used iron-oxide nanoparticles, core/shell structured iron/iron-oxide nanoparticles offer a much stronger T{sub 2} shortening effect than that of iron-oxide with the same core size due to their better magnetic properties. -- Highlights: ► Core/shell Fe/Fe-oxide nanoparticles were synthesized by organo-metallic synthesis. ► Water dispersibility was obtained by coating particles with a polysiloxane diblock copolymer. ► In comparison to Fe-oxide, Fe/Fe-oxide nanoparticles offer a much stronger T{sub 2} shortening effect.

  17. Core-shell structured PEO-chitosan nanofibers by coaxial electrospinning.

    Science.gov (United States)

    Pakravan, Mehdi; Heuzey, Marie-Claude; Ajji, Abdellah

    2012-02-13

    Core-shell structured PEO-chitosan nanofibers have been produced using a coaxial electrospinning setup. PEO and chitosan solutions, both in an aqueous acetic acid solvent, were used as the inner (core) and outer (shell) layer, respectively. Uniform-sized defect-free nanofibers of 150-190 nm diameter were produced. In addition, hollow nanofibers could be obtained subsequent to PEO washing of the membranes. The core-shell nanostructure and existence of chitosan on the shell layer were confirmed by TEM images obtained before and after washing the PEO content with water. The presence of chitosan on the surface of the composite nanofibers was further supported by XPS studies. The chitosan and PEO compositions in the nanofibrous mats were determined by TGA analysis, which were similar to their ratio in the feed solutions. The local compositional homogeneity of the membranes and the efficiency of the washing step to remove PEO were also verified by FTIR. In addition, DSC and XRD were used to characterize the crystalline structure and morphology of the co-electrospun nonwoven mats. The prepared coaxial nanofibers (hollow and solid) have several potential applications due to the presence of chitosan on their outer surfaces.

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

    Energy Technology Data Exchange (ETDEWEB)

    Hirai, Mitsuhiro, E-mail: mhirai@gunma-u.ac.jp; Kimura, Ryota; Takeuchi, Kazuki; Hagiwara, Yoshihiko [Gunma University, 4-2 Aramaki, Maebashi, Gunma 371-8510 (Japan); Kawai-Hirai, Rika [Gunma University, 3-39-15 Shouwa, Maebashi 371-8512 (Japan); Ohta, Noboru [JASRI, 1-1-1 Kuoto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Igarashi, Noriyuki; Shimuzu, Nobutaka [KEK-PF, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)

    2013-11-01

    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.

  19. New development in welding thin-shell aluminum alloy structures with high strength

    Institute of Scientific and Technical Information of China (English)

    徐文立; 范成磊; 方洪渊; 田锡唐

    2004-01-01

    From the viewpoint of welding mechanics, two new welding methods-welding with trailing peening and welding with trailing impactive rolling were introduced. For aluminum alloy thin-shell structures with high strength, welding will lead to hot cracking, poor joint and distortion. In order to solve them, trailing impactive device was used behind welding torch to impact the different positions of welded joints, thus realizing the welding with free-hot cracking, low distortion and joint strengthening. By use of impactive rolling wheels instead of peening heads, the outlook of welded specimen can be improved and stress concentration at weld toes can be reduced. Equipment of this technology is simple and portable. It can used to weld sheets, longitudinal and ring-like beams of tube-like structures, as well as the thin-shell structures with closed welds such as flanges and hatches. So the technology has the wide application foreground in the fields of aviation and aerospace.

  20. Synthesis and Surface Properties of Silica Spheres with Core Shell Structure by One Convenient Method

    Directory of Open Access Journals (Sweden)

    D. P. Das

    2009-01-01

    Full Text Available Earlier, we have published a paper on the preparation of silica sphere using propanol as cosurfactant. We report here a highly cost-effective method of preparation of mesoporous silica spheres with core shell structure using sodium silicate as silica precursor, cetyltrimethyl ammonium bromide (CTAB as surfactant, and methanol as cosurfactant. Thus after removal of the template by dissolutions or/and activation at higher temperature, mesoporous silica spheres with core shell structure were obtained. The products prepared with methanol to CTAB molar ratio 8.5 : 1 were confirmed to give best results. All the spherical products have very large surface area (∼589–1044 m2/g, pore volume (∼0.98–1.41 cm3/g, and ordered pore structure.

  1. The stability and catalytic activity of W13@Pt42 core-shell structure

    Science.gov (United States)

    Huo, Jin-Rong; Wang, Xiao-Xu; Li, Lu; Cheng, Hai-Xia; Su, Yan-Jing; Qian, Ping

    2016-10-01

    This paper reports a study of the electronic properties, structural stability and catalytic activity of the W13@Pt42 core-shell structure using the First-principles calculations. The degree of corrosion of W13@Pt42 core-shell structure is simulated in acid solutions and through molecular absorption. The absorption energy of OH for this structure is lower than that for Pt55, which inhibits the poison effect of O containing intermediate. Furthermore we present the optimal path of oxygen reduction reaction catalyzed by W13@Pt42. Corresponding to the process of O molecular decomposition, the rate-limiting step of oxygen reduction reaction catalyzed by W13@Pt42 is 0.386 eV, which is lower than that for Pt55 of 0.5 eV. In addition by alloying with W, the core-shell structure reduces the consumption of Pt and enhances the catalytic efficiency, so W13@Pt42 has a promising perspective of industrial application.

  2. The stability and catalytic activity of W13@Pt42 core-shell structure

    Science.gov (United States)

    Huo, Jin-Rong; Wang, Xiao-Xu; Li, Lu; Cheng, Hai-Xia; Su, Yan-Jing; Qian, Ping

    2016-01-01

    This paper reports a study of the electronic properties, structural stability and catalytic activity of the W13@Pt42 core-shell structure using the First-principles calculations. The degree of corrosion of W13@Pt42 core-shell structure is simulated in acid solutions and through molecular absorption. The absorption energy of OH for this structure is lower than that for Pt55, which inhibits the poison effect of O containing intermediate. Furthermore we present the optimal path of oxygen reduction reaction catalyzed by W13@Pt42. Corresponding to the process of O molecular decomposition, the rate-limiting step of oxygen reduction reaction catalyzed by W13@Pt42 is 0.386 eV, which is lower than that for Pt55 of 0.5 eV. In addition by alloying with W, the core-shell structure reduces the consumption of Pt and enhances the catalytic efficiency, so W13@Pt42 has a promising perspective of industrial application. PMID:27759038

  3. The stability and catalytic activity of W13@Pt42 core-shell structure.

    Science.gov (United States)

    Huo, Jin-Rong; Wang, Xiao-Xu; Li, Lu; Cheng, Hai-Xia; Su, Yan-Jing; Qian, Ping

    2016-10-19

    This paper reports a study of the electronic properties, structural stability and catalytic activity of the W13@Pt42 core-shell structure using the First-principles calculations. The degree of corrosion of W13@Pt42 core-shell structure is simulated in acid solutions and through molecular absorption. The absorption energy of OH for this structure is lower than that for Pt55, which inhibits the poison effect of O containing intermediate. Furthermore we present the optimal path of oxygen reduction reaction catalyzed by W13@Pt42. Corresponding to the process of O molecular decomposition, the rate-limiting step of oxygen reduction reaction catalyzed by W13@Pt42 is 0.386 eV, which is lower than that for Pt55 of 0.5 eV. In addition by alloying with W, the core-shell structure reduces the consumption of Pt and enhances the catalytic efficiency, so W13@Pt42 has a promising perspective of industrial application.

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

    Science.gov (United States)

    Wang, Qiang; Wang, Xinyan; Liu, Jianlan; Yang, Yanhui

    2017-02-01

    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@Cu12@Ni42 is more stable than two-shell Cu13@Ni42, while two-shell Ni13@Cu42 is more stable than three-shell Cu@Ni12@Cu42. 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.

  5. Correlation between the energy shell structure and geometry in metallic nanoclusters: quasi-resonance states, isotope effect

    CERN Document Server

    Kresin, Vladimir

    2008-01-01

    Metallic nanoclusters displaying electronic shell structure exhibit the special feature of a correlation between their geometry and the number of delocalized electrons . Their shape evolution can be described as a quantum oscillation between quasi-resonant states (prolate and oblate configurations) whose amplitudes depend upon the degree of shell filling. The picture explains the evolution of absorption spectra and predicts a peculiar isotope effect .

  6. Rational Integration of Inbuilt Aperture with Mesoporous Framework in Unusual Asymmetrical Yolk-Shell Structures for Energy Storage and Conversion.

    Science.gov (United States)

    Zhu, Ting; Zhu, Liangliang; Wang, Jing; Ho, Ghim Wei

    2016-12-07

    Despite the attractive benefits of hollow structures as electrodes for advanced energy storage-conversion capabilities, one prevailing shortcoming is their compromised structural integrity and volumetric energy density due to the introduction of an ultrathin shell with an excessively underutilized large hollow cavity. Herein, we report a facile and template-free synthetic route to realize unusual asymmetrical yolk-shell (AYs) structures composed of mixed-valence NiCo2O4 material. Explicitly, this work highlights the unusual off-central core, an AYs structure that encompasses a hemispherical hollow interior, and a mesoporous solid counterpart. As such, it retains desirable hollow structural characteristics while favorably precludes the excessive unexploited hollow interior space for increased active material packing. Unlike the conventional symmetrical yolk-shell (SYs) which is composed of a porous shell framework radially throughout the structure, the mesoporous solid constitution of the AYs structure offers an inbuilt reinforced framework to support the partial porous shell and concurrently leaves sufficient void for volumetric buffering. Another unique structural feature of the AYs structure is the formation of a submicron aperture or opening on the shell that enhances accessibility of electrolyte diffusion. All of these synergistic structural features of NiCo2O4 AYs structures enhance the pseudocapacitive and electrocatalytic properties.

  7. 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.

  8. X-ray photoelectron spectroscopy studies on core-shell structured nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, M. [Surface Physics Division, Saha Institute of Nuclear Physics, Kolkata 700064 (India); Basu, S.; Ghosh, B. [Unit on Nano Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India); Chakravorty, D. [Unit on Nano Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India)], E-mail: mlsdc@iacs.res.in

    2007-08-15

    Core-shell nanostructures were grown in silica-based glasses. Copper-copper oxide and iron-iron oxide structures had diameters in the range 3-6 nm, with shell thicknesses {approx}1-2 nm. Silver-lithium niobate core-shell nanostructures had diameters in the range 4.2-46 nm and thicknesses varying from 2.2 to 22 nm. X-ray photoelectron spectroscopy studies were carried out on all these specimens. The analyses of these results show the presence of Cu{sup +}/Cu{sup 2+}, Fe{sup 2+}/Fe{sup 3+} and Nb{sup 4+}/Nb{sup 5+} valence states in the above three systems. Electrical resistivity data were fitted satisfactorily to the small polaron hopping model in the case of copper and iron-containing specimens. The presence of ions in the lithium niobate shell provides direct evidence of the formation of localized states between which variable range hopping conduction can be effected.

  9. Quadratic solid-shell elements for nonlinear structural analysis and sheet metal forming simulation

    Science.gov (United States)

    Wang, Peng; Chalal, Hocine; Abed-Meraim, Farid

    2017-01-01

    In this paper, two quadratic solid-shell (SHB) elements are proposed for the three-dimensional modeling of thin structures. These consist of a 20-node hexahedral solid-shell element, denoted SHB20, and its 15-node prismatic counterpart, denoted SHB15. The formulation of these elements is extended in this work to include geometric and material nonlinearities, for application to problems involving large displacements and rotations as well as plasticity. For this purpose, the SHB elements are coupled with large-strain anisotropic elasto-plastic constitutive equations for metallic materials. Although based on a purely three-dimensional approach, several modifications are introduced in the formulation of these elements to provide them with interesting shell features. In particular, a special direction is chosen to represent the thickness, along which a user-defined number of integration points are located. Furthermore, for efficiency requirements and for alleviating locking phenomena, an in-plane reduced-integration scheme is adopted. The resulting formulations are implemented into the finite element software ABAQUS/Standard and, to assess their performance, a variety of nonlinear benchmark problems are investigated. Attention is then focused on the simulation of various complex sheet metal forming processes, involving large strain, anisotropic plasticity, and double-sided contact. From all simulation results, it appears that the SHB elements represent an interesting alternative to traditional shell and solid elements, due to their versatility and capability of accurately modeling selective nonlinear benchmark problems as well as complex sheet metal forming processes.

  10. 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.

  11. New Shell Structures and Their Ground Electronic States in Spherical Quantum Dots (II) under Magnetic Field

    Science.gov (United States)

    Asari, Yusuke; Takeda, Kyozaburo; Tamura, Hiroyuki

    2005-04-01

    We theoretically studied the electronic structure of the three-dimensional spherical parabolic quantum dot (3D-SPQD) under a magnetic field. We obtained the quantum dot orbitals (QDOs) and determined the ground state by using the extended UHF approach where the expectation values of the z component of the total orbital angular momentum are conserved during the scf-procedure. The single-electron treatment predicts that the applied magnetic field (B) creates k-th new shells at the magnetic field of Bk=k(k+2)/(k+1)ω0 with the shell-energy interval of \\hbarω0/(k+1), where ω0(=\\hbar/m*l02) is the characteristic frequency originating from the spherical parabolic confinement potential. These shells are formed by the level crossing among multiple QDOs. The interelectron interaction breaks the simple level crossing but causes complicated dependences among the total energy, the chemical potential and their differences (magic numbers) with the magnetic field or the number of confinement electrons. The ground state having a higher spin multiplicity is theoretically predicted on the basis of the \\textit{quasi}-degeneracies of the QDOs around these shells.

  12. Quadratic solid-shell elements for nonlinear structural analysis and sheet metal forming simulation

    Science.gov (United States)

    Wang, Peng; Chalal, Hocine; Abed-Meraim, Farid

    2016-10-01

    In this paper, two quadratic solid-shell (SHB) elements are proposed for the three-dimensional modeling of thin structures. These consist of a 20-node hexahedral solid-shell element, denoted SHB20, and its 15-node prismatic counterpart, denoted SHB15. The formulation of these elements is extended in this work to include geometric and material nonlinearities, for application to problems involving large displacements and rotations as well as plasticity. For this purpose, the SHB elements are coupled with large-strain anisotropic elasto-plastic constitutive equations for metallic materials. Although based on a purely three-dimensional approach, several modifications are introduced in the formulation of these elements to provide them with interesting shell features. In particular, a special direction is chosen to represent the thickness, along which a user-defined number of integration points are located. Furthermore, for efficiency requirements and for alleviating locking phenomena, an in-plane reduced-integration scheme is adopted. The resulting formulations are implemented into the finite element software ABAQUS/Standard and, to assess their performance, a variety of nonlinear benchmark problems are investigated. Attention is then focused on the simulation of various complex sheet metal forming processes, involving large strain, anisotropic plasticity, and double-sided contact. From all simulation results, it appears that the SHB elements represent an interesting alternative to traditional shell and solid elements, due to their versatility and capability of accurately modeling selective nonlinear benchmark problems as well as complex sheet metal forming processes.

  13. On-shell diagrammatics and the perturbative structure of planar gauge theories

    CERN Document Server

    Benincasa, Paolo

    2015-01-01

    We discuss the on-shell diagrammatic representation of theories less special than maximally supersymmetric Yang-Mills. In particular, we focus on planar $\\mathcal{N}\\,\\le\\,2$ gauge theories, including pure Yang-Mills. For such a class of theories, the on-shell diagrammatics is endowed with a decoration which carries the information on the helicity of the coherent states. In the first part of the paper we extensively discuss the properties of this decorated diagrammatics. Particular relevance have the helicity flows that the decoration induces on the diagrams, which allows to identify the different classes of singularities and, consequentely, the singularity structure of the on-shell processes. The second part of the paper establishes a link between the decorated on-shell diagrammatics and the scattering amplitudes for the theories under examination. We prove that an all-loop recursion relation at integrand level holds also for $\\mathcal{N}\\,=\\,1,\\,2$, while for $\\mathcal{N}\\,=\\,0$ we are able to set up a prel...

  14. Off-shell Corrections and Moments of the Deep Inelastic Nuclear Structure Functions

    CERN Document Server

    Cothran, C D; Liuti, S

    1998-01-01

    We present an improved method for handling off-shell effects in deep inelastic nuclear scattering. With a firm understanding of the effects of the nuclear wave function, including these off-shell corrections as well as binding and nucleon-nucleon correlations, we can begin to examine the role of QCD in nuclei through an analysis of the moments of the nuclear structure function. Our analysis is aimed at extracting the Q^2 dependence of the moments of the nucleon structure function by using the recent high x world Iron data and by properly removing nuclear effects from the perturbative contribution. In addition, we compare quantitatively the behavior of the extracted moments with a simple O(1/Q^2) phenomenological form and we determine the mass term for this parametrization.

  15. Age structure, carbonate production and shell loss rate in an Early Miocene reef of the giant oyster Crassostrea gryphoides

    Science.gov (United States)

    Harzhauser, Mathias; Djuricic, Ana; Mandic, Oleg; Neubauer, Thomas A.; Zuschin, Martin; Pfeifer, Norbert

    2016-02-01

    We present the first analysis of population structure and cohort distribution in a fossil oyster shell bed based on 1121 shells of the giant oyster Crassostrea gryphoides (von Schlotheim, 1813). Data derive from terrestrial laser scanning of a Lower Miocene shell bed covering 459 m2. Within two transects, individual shells were manually outlined on a digital surface model and cross-checked based on high-resolution orthophotos, resulting in accurate information on center line length and area of exposed shell surface. A growth model was calculated, revealing this species as the fastest growing and largest Crassostrea known so far. Non-normal distribution of size, area and age data hints at the presence of at least four distinct recruitment cohorts. The rapid decline of frequency amplitudes with age is interpreted to be a function of mortality and shell loss. The calculated shell half-lives range around a few years, indicating that oyster reefs were geologically short-lived structures, which could have been fully degraded on a decadal scale. Crassostrea gryphoides reefs were widespread and common along the Miocene circum-Tethyan coasts. Given its enormous growth performance of ˜ 150 g carbonate per year this species has been an important carbonate producer in estuarine settings. Yet, the rapid shell loss impeded the formation of stable structures comparable to coral reefs.

  16. Influence of SiO2 shell thickness on power conversion efficiency in plasmonic polymer solar cells with Au nanorod@SiO2 core-shell structures

    Science.gov (United States)

    Zhang, Ran; Zhou, Yongfang; Peng, Ling; Li, Xue; Chen, Shufen; Feng, Xiaomiao; Guan, Yuqiao; Huang, Wei

    2016-04-01

    Locating core-shell metal nanoparticles into a photoactive layer or at the interface of photoactive layer/hole extraction layer is beneficial for fully employing surface plasmon energy, thus enhancing power conversion efficiency (PCE) in plasmonic organic photovoltaic devices (OPVs). Herein, we first investigated the influence of silica shell thickness in Au nanorods (NRs)@SiO2 core-shell structures on OPV performances by inserting them into poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) and thieno[3,4-b]thiophene/benzodithiophene (PTB7) interface, and amazedly found that a 2–3 nm silica shell onto Au NRs induces a highest short-circuit current density of 21.2 mA cm‑2 and PCE of 9.55%. This is primarily due to an extremely strong local field and a much slower attenuation of localized surface plasmon resonance around ultrathin silica-coated Au NRs, with which the field intensity remains a high value in the active layer, thus sufficiently improves the absorption of PTB7. Our work provides a clear design concept on precise control of the shell of metal nanoparticles to realize high performances in plasmonic OPVs.

  17. Draft Crystal Structure of the Vault Shell at 9-Å Resolution

    OpenAIRE

    Anderson, Daniel H; Kickhoefer, Valerie A.; Stuart A Sievers; Rome, Leonard H.; David Eisenberg

    2007-01-01

    Vaults are the largest known cytoplasmic ribonucleoprotein structures and may function in innate immunity. The vault shell self-assembles from 96 copies of major vault protein and encapsulates two other proteins and a small RNA. We crystallized rat liver vaults and several recombinant vaults, all among the largest non-icosahedral particles to have been crystallized. The best crystals thus far were formed from empty vaults built from a cysteine-tag construct of major vault protein (termed cpMV...

  18. 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.

  19. Amorphous Silicon Solar cells with a Core-Shell Nanograting Structure

    CERN Document Server

    Yang, L; Okuno, Y; He, S

    2011-01-01

    We systematically investigate the optical behaviors of an amorphous silicon solar cell based on a core-shell nanograting structure. The horizontally propagating Bloch waves and Surface Plasmon Polariton (SPP) waves lead to significant absorption enhancements and consequently short-circuit current enhancements of this structure, compared with the conventional planar one. The perpendicular carrier collection makes this structure optically thick and electronically thin. An optimal design is achieved through full-field numerical simulation, and physical explanation is given. Our numerical results show that this configuration has ultrabroadband, omnidirectional and polarization-insensitive responses, and has a great potential in photovoltaics.

  20. MAGNETIC CORE SHELL STRUCTURES: from 0D to 1D assembling.

    Science.gov (United States)

    Ficai, Denisa; Ficai, Anton; Dinu, Elena; Oprea, Ovidiu; Sonmez, Maria; Keler, Memduh Kagan; Sahin, Yesim Muge; Ekren, Nazmi; Inan, Ahmet Talat; Daglilar, Sibel; Gunduz, Oguzhan

    2015-01-01

    Material research and development studies are focused on different techniques of bringing out nanomaterials with desired characteristics and properties. From the point of view of materials development, nowadays scientists are strongly focused on obtaining materials with predefined characteristics and properties. The morphology control seems to be a determinant factor and increasing attention is devoted to this aspect. At this moment it is possible to engineer the material's features by using different methods and materials combination for both medical and industrial applications. In the applications of chemistry and synthesis, biology, mechanics, optics solar cells and microelectronics tailoring the adjustable parameters of stoichiometry, chemical structure, shape and segregation are evaluated and opens new fields. Because of the magnetic features of nanoparticles and durable particle size, less than 100 nm, this study is aiming to describe their uses in practical applications. That's why the whole hydrodynamic magnetic core shell topic will be reviewed on this paper. Additionally, the properties acting in general sight in solid-state physics are utilized for material selection and for defining issue connecting the core, shell structure and their producing properties. Here, in the study of core/shell nanoparticle various physical and chemical synthesis routes and the effect of electrospun method are briefly discussed. Starting from a real void of the scientific literature, the existent data related to the 1D magnetic electrospun materials are reviewed. The perspectives in the medical, environmental or energetic sector is great and bring some real advantages related to the 0D core@shell structures because both mechanical and biological properties are dependent on the morphology of the materials.

  1. Structural Evolution of Core-Shell Gold Nanoclusters: Aun(-) (n = 42-50).

    Science.gov (United States)

    Pande, Seema; Huang, Wei; Shao, Nan; Wang, Lei-Ming; Khetrapal, Navneet; Mei, Wai-Ning; Jian, Tian; Wang, Lai-Sheng; Zeng, Xiao Cheng

    2016-11-22

    Gold nanoclusters have attracted great attention in the past decade due to their remarkable size-dependent electronic, optical, and catalytic properties. However, the structures of large gold clusters are still not well-known because of the challenges in global structural searches. Here we report a joint photoelectron spectroscopy (PES) and theoretical study of the structural evolution of negatively charged core-shell gold nanoclusters (Aun(-)) for n = 42-50. Photoelectron spectra of size-selected Aun(-) clusters are well resolved with distinct spectral features, suggesting a dominating structural type. The combined PES data and density functional calculations allow us to systematically identify the global minimum or candidates of the global minima of these relatively large gold nanoclusters, which are found to possess low-symmetry structures with gradually increasing core sizes. Remarkably, the four-atom tetrahedral core, observed first in Au33(-), continues to be highly robust and is even present in clusters as large as Au42(-). Starting from Au43(-), a five-atom trigonal bipyramidal core appears and persists until Au47(-). Au48(-) possesses a six-atom core, while Au49(-) and Au50(-) feature seven- and eight-atom cores, respectively. Notably, both Au46(-) and Au47(-) contain a pyramidal Au20 motif, which is stacked with another truncated pyramid by sharing a common 10-atom triangular face. The present study sheds light on our understanding of the structural evolution of the medium-sized gold nanoclusters, the shells and core as well as how the core-shell structures may start to embrace the golden pyramid (bulk-like) fragment.

  2. Lifetime analysis of individual-atom contacts and crossover to geometric-shell structures in unstrained silver nanowires

    Directory of Open Access Journals (Sweden)

    Christian Obermair

    2011-11-01

    Full Text Available We study the crossover of quantum point contacts from (i individual-atom contacts to (ii electronic-shell effects and finally to (iii geometric-shell effects in electrochemically deposited silver contacts. The method allows the fabrication of mechanically unstrained structures, which is a requirement for determining the individual atomic configuration by means of a detailed lifetime analysis of their conductance. Within the geometric-shell model, the sequence of conductance maxima is explained quantitatively based on the crystal structure data of silver, and the growth mechanism of the nanowires is discussed.

  3. {ital s} -{ital p} Hybridization and Electron Shell Structures in Aluminum Clusters: A Photoelectron Spectroscopy Study

    Energy Technology Data Exchange (ETDEWEB)

    Li, X.; Wu, H.; Wang, X.; Wang, L. [Department of Physics, Washington State University, 2710 University Drive, Richland, Washington 99352-1671 (United States)]|[W. R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, MS K8-88, P.O. Box 999, Richland, Washington 99352 (United States)

    1998-08-01

    Using photoelectron spectroscopy of size-selected Al{sub x}{sup {minus}} (x=1{endash}162) clusters, we studied the electronic structure evolution of Al{sub x} and observed that the Al 3s - and 3p -derived bands evolve and broaden with cluster size and begin to overlap at Al{sub 9} . Direct spectroscopic signatures were obtained for electron shell structures with spherical shell closings at Al{sub 11}{sup {minus}} , Al{sub 13}{sup {minus}} , Al{sub 19}{sup {minus}} , Al{sub 23}{sup {minus}} , Al{sub 35}{sup {minus}} , Al{sub 37}{sup {minus}} , Al{sub 46} , Al{sub 52} , Al{sub 55}{sup {minus}} , Al{sub 56} , Al{sub 66} , and Al{sub 73}{sup {minus}} . The electron shell effect diminishes above Al{sub 75} and new spectral features appearing in Al{sub x}{sup {minus}} (x{gt}100) suggest a possible geometrical packing effect in large clusters. {copyright} {ital 1998} {ital The American Physical Society}

  4. SYNTHESIS AND CHARACTERIZATION OF NANO METALS WITH CORE-SHELL STRUCTURE

    Institute of Scientific and Technical Information of China (English)

    Ru-Shi Liu; Hau-Ming Chen; Shu-Fen Hu

    2004-01-01

    Using AUcore-Ptshell as an example, the synthesis and characterization of nano metals with core-shell structure is demonstrated in a systematic study on the amount-dependent morphology change in a series of Au-Pt bimetallic nanoparticles synthesized using chemical reduction. While the amount of Au precursor is kept constant throughout the whole series of compounds to obtain a fixed Au core size (~7.5 nm), the Au/Pt ratio is varied from 1/1 to 1/4 in order to synthesize Pt shell layers of different thickness. We observed a remarkable shift of surface plasmon band to around 410 nm. With the aid of high resolution transmission electron microscope (HRTEM) and energy-dispersive spectrometer (EDS), the composition of the shell layer is found to be a Pt-enriched Au-Pt alloy. As the amount of Pt increases, string-like Pt clusters form on the surface of the nanoparticles. The average diameter of these Pt clusters is about 2 nm. This special structure may possess unique catalytic properties.

  5. Synthesis and Microwave Absorption Properties of Core-Shell Structured Co3O4-PANI Nanocomposites

    Directory of Open Access Journals (Sweden)

    Hongyan Xu

    2015-01-01

    Full Text Available The core-shell structured Co3O4-PANI nanocomposites have been successfully prepared using an in situ polymerization method, while the core Co3O4 nanoparticles were synthesized by carbon-assisted method using degreasing cotton as a template. The obtained samples were characterized by XRD, TEM, FTIR, and XPS. The results indicated that the amorphous PANI was well covered on the surface of the spinel Co3O4 and the Co3O4-PANI with core-shell structure was formed with particle size of about 100 nm. The interfacial interaction of the core-shell nanocomposite greatly enhances the microwave absorption properties. The maximum reflection loss of Co3O4-PANI is up to −45.8 dB at 11.7 GHz with a thickness of 2.5 mm and the adsorption bandwidth with the reflection loss below −10 dB reaches 14.1 GHz ranging from 3.9 to 18 GHz when the thickness is between 2 and 5.5 mm. Therefore, the facilely synthesized and low-cost Co3O4-PANI nanocomposite with superior microwave absorption properties can be a promising nanomaterial for high efficient microwave absorption.

  6. Synthesis and characterization of magnetic polymer microspheres with a core-shell structure

    Institute of Scientific and Technical Information of China (English)

    Ming; Lu; Shu; Bai; Kun; Yang; Yan; Sun

    2007-01-01

    Non-porous magnetic polymer microspheres with a core-shell structure were prepared by a novel micro-suspension polymerization technique.A stable iron oxide ferrofluid was used to supply the magnetic core, and the polymeric shell was made of glycidyl methacrylate (GMA monomer)and ethylene dimethacrylate (cross-linker). In the preparation, polyvinyl alcohol was used as the stabilizer, and a lauryl alcohol mixture as the dispersant. The influence of various conditions such as aqueous phase volume, GMA and initiator amounts, reaction time and stirring speed on the character of the microspheres was investigated. The magnetic microspheres were then characterized briefly. The results indicate that the microspheres with active epoxy groups had a narrow size distribution range from 1 to 10 μm with a volume-weighted mean diameter of 4.5 μm.The saturation magnetization reached 19.9 emu/g with little coercivity and remanence.

  7. Open structure ZnO/CdSe core/shell nanoneedle arrays for solar cells.

    Science.gov (United States)

    Chen, Yanxue; Wei, Lin; Zhang, Guanghua; Jiao, Jun

    2012-09-20

    Open structure ZnO/CdSe core/shell nanoneedle arrays were prepared on a conducting glass (SnO2:F) substrate by solution deposition and electrochemical techniques. A uniform CdSe shell layer with a grain size of approximately several tens of nanometers was formed on the surface of ZnO nanoneedle cores after annealing at 400°C for 1.5 h. Fabricated solar cells based on these nanostructures exhibited a high short-circuit current density of about 10.5 mA/cm2 and an overall power conversion efficiency of 1.07% with solar illumination of 100 mW/cm2. Incident photo-to-current conversion efficiencies higher than 75% were also obtained.

  8. 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.

  9. Surface Plasmon Resonance from Bimetallic Interface in Au–Ag Core–Shell Structure Nanowires

    Directory of Open Access Journals (Sweden)

    Zhu Jian

    2009-01-01

    Full Text Available Abstract Transverse surface plasmon resonances (SPR in Au–Ag and Ag–Au core–shell structure nanowires have been investigated by means of quasi-static theory. There are two kinds of SPR bands resulting from the outer surface of wall metal and the interface between core and wall metals, respectively. The SPR corresponding to the interface, which is similar to that of alloy particle, decreases and shifts obviously with increasing the wall thickness. However, the SPR corresponding to the outer surface, which is similar to that of pure metal particle, increases and shifts slightly with increasing the wall thickness. A mechanism based on oscillatory surface electrons under coulombic attraction is developed to illuminate the shift fashion of SPR from bimetallic core–shell interface. The net charges and extra coulombic force in metallic wall affect the SPR energy and the shift fashion.

  10. Structural optical correlated properties of SnO2/Al2O3 core@ shell heterostructure

    Science.gov (United States)

    Heiba, Zein K.; Imam, N. G.; Bakr Mohamed, Mohamed

    2016-07-01

    Nano size polycrystalline samples of the core@shell heterostructure of SnO2 @ xAl2O3 (x = 0, 25, 50, 75 wt.%) were synthesized by sol-gel technique. The resulting samples were characterized with fourier transform infrared spectroscopy (FT-IR), photoluminescence (PL) and X-ray powder diffraction (XRD). The XRD patterns manifest diffraction peaks of SnO2 as main phase with weak peaks corresponding to Al2O3 phase. The formation of core@ shell structure is confirmed by TEM images and Rietveld quantitative phase analysis which revealed that small part of Al2O3 is incorporated into the SnO2 lattice while the main part (shell) remains as a separate phase segregated on the grain boundary surface of SnO2 (core). It is found that the grain size of the mixed oxides SnO2 @ xAl2O3 is below 10 nm while for pure SnO2 it is over 41 nm, indicating that alumina can effectively prevent SnO2 from further growing up in the process of calcination. This is confirmed by the large increase in the specific surface area for mixed oxide samples. The PL emission showed great dependence on the structure properties analyzed by XRD and FTIR. The PL results recommend Al2O3@SnO2 core@shell heterostructure to be a promising short-wavelength luminescent optoelectronic devices for blue, UV, and laser light-emitting diodes.

  11. Structural distortion of biogenic aragonite in strongly textured mollusc shell layers

    Energy Technology Data Exchange (ETDEWEB)

    Chateigner, D., E-mail: daniel.chateigner@ensicaen.f [CRISMAT-ENSICAEN, Universite de Caen Basse-Normandie, 6 Bd. M. Juin, 14050 Caen (France); Ouhenia, S. [CRISMAT-ENSICAEN, Universite de Caen Basse-Normandie, 6 Bd. M. Juin, 14050 Caen (France); Lab. De Physique, Faculte des Sciences Exactes, Bejaia 06000 (Algeria); Krauss, C. [CRISMAT-ENSICAEN, Universite de Caen Basse-Normandie, 6 Bd. M. Juin, 14050 Caen (France); Belkhir, M. [Lab. De Physique, Faculte des Sciences Exactes, Bejaia 06000 (Algeria); Morales, M. [CIMAP-ENSICAEN, Universite de Caen Basse-Normandie, 6 Bd. M. Juin, 14050 Caen (France)

    2010-02-15

    The stabilisation of strong textures in mollusc shells has for long been a strong drawback towards precise structural determinations of these natural biocomposites. We demonstrate here on several crossed lamellar and nacre layers from two gastropods (Charonia lampas lampas and Haliotis tuberculata tuberculata) and one bivalve (Pinctada maxima), that on real specimens (without grinding or specific preparation), the textural information can be used efficiently for precise structural determination of the biogenic aragonite. This is done through the combination of orientation distribution function and cyclic Rietveld refinements on several hundreds to thousands of diffractions diagrams.

  12. Synthesis and characterisation of core-shell structures for orthopaedic surgery.

    Science.gov (United States)

    Rusen, Edina; Zaharia, Cătălin; Zecheru, Teodora; Mărculescu, Bogdan; Filmon, Robert; Chappard, Daniel; Bădulescu, Roxana; Cincu, Corneliu

    2007-01-01

    This paperwork deals with the obtaining and characterisation of new acrylic cements for bone surgery. The final mixture of cement contains derivatives of methacryloyloxyethyl phosphate, methacrylic acid or 2-acrylamido-2-methyl-1-propane sulphonic acid. The idea of using these monomers is sustained by their ability to form ionic bonds with barium, which is responsible for X-ray reflection and by the biocompatibility of these structures. The strategy consists in the obtaining of core-shell structures through heterogeneous polymerisation, which are used for final cement's manufacture. The orthopaedic cements were characterised by SEM, EDX, compression resistance and cytotoxicity assays.

  13. Age structure, carbonate production and shell loss rate in an Early Miocene reef of the giant oyster Crassostrea gryphoides

    Directory of Open Access Journals (Sweden)

    M. Harzhauser

    2015-09-01

    Full Text Available We present the first analysis of population structure and cohort distribution in a fossil oyster reef based on more than 1121 shells of the giant oyster Crassostrea gryphoides (Schlotheim, 1813. Data derive from Terrestrial Laser Scanning of a Lower Miocene shell bed covering 459 m2. Within two transects, individual shells were manually outlined on a digital surface model and cross-checked based on high-resolution orthophotos, resulting in accurate information on center line length and area of exposed shell surface. A growth model was calculated, revealing this species as the fastest growing and largest Crassostrea known so far. Non-normal distribution of size, area and age data hints at the presence of at least four distinct recruitment cohorts. The rapid decline of frequency amplitudes with age is interpreted to be a function of mortality and shell loss. The calculated shell half-lives range around few years, indicating that oyster reefs were geologically short-lived structures, which could have been fully degraded on a decadal scale. Crassostrea gryphoides reefs were widespread and common along the Miocene circum-Tethyan coasts. Given its enormous growth performance of ~ 150 g carbonate per year this species has been an important carbonate producer in estuarine settings. Yet, the rapid shell loss impeded the formation of stable structures comparable to coral reefs.

  14. Diverse Melting Modes and Structural Collapse of Hollow Bimetallic Core-Shell Nanoparticles: A Perspective from Molecular Dynamics Simulations

    Science.gov (United States)

    Huang, Rao; Shao, Gui-Fang; Zeng, Xiang-Ming; Wen, Yu-Hua

    2014-11-01

    Introducing hollow structures into metallic nanoparticles has become a promising route to improve their catalytic performances. A fundamental understanding of thermal stability of these novel nanostructures is of significance for their syntheses and applications. In this article, molecular dynamics simulations have been employed to offer insights into the thermodynamic evolution of hollow bimetallic core-shell nanoparticles. Our investigation reveals that for hollow Pt-core/Au-shell nanoparticle, premelting originates at the exterior surface, and a typical two-stage melting behavior is exhibited, similar to the solid ones. However, since the interior surface provides facilitation for the premelting initiating at the core, the two-stage melting is also observed in hollow Au-core/Pt-shell nanoparticle, remarkably different from the solid one. Furthermore, the collapse of hollow structure is accompanied with the overall melting of the hollow Pt-core/Au-shell nanoparticle while it occurs prior to that of the hollow Au-core/Pt-shell nanoparticle and leads to the formation of a liquid-core/solid-shell structure, although both of them finally transform into a mixing alloy with Au-dominated surface. Additionally, the existence of stacking faults in the hollow Pt-core/Au-shell nanoparticle distinctly lowers its melting point. This study could be of great importance to the design and development of novel nanocatalysts with both high activity and excellent stability.

  15. Diverse Melting Modes and Structural Collapse of Hollow Bimetallic Core-Shell Nanoparticles: A Perspective from Molecular Dynamics Simulations

    Science.gov (United States)

    Huang, Rao; Shao, Gui-Fang; Zeng, Xiang-Ming; Wen, Yu-Hua

    2014-01-01

    Introducing hollow structures into metallic nanoparticles has become a promising route to improve their catalytic performances. A fundamental understanding of thermal stability of these novel nanostructures is of significance for their syntheses and applications. In this article, molecular dynamics simulations have been employed to offer insights into the thermodynamic evolution of hollow bimetallic core-shell nanoparticles. Our investigation reveals that for hollow Pt-core/Au-shell nanoparticle, premelting originates at the exterior surface, and a typical two-stage melting behavior is exhibited, similar to the solid ones. However, since the interior surface provides facilitation for the premelting initiating at the core, the two-stage melting is also observed in hollow Au-core/Pt-shell nanoparticle, remarkably different from the solid one. Furthermore, the collapse of hollow structure is accompanied with the overall melting of the hollow Pt-core/Au-shell nanoparticle while it occurs prior to that of the hollow Au-core/Pt-shell nanoparticle and leads to the formation of a liquid-core/solid-shell structure, although both of them finally transform into a mixing alloy with Au-dominated surface. Additionally, the existence of stacking faults in the hollow Pt-core/Au-shell nanoparticle distinctly lowers its melting point. This study could be of great importance to the design and development of novel nanocatalysts with both high activity and excellent stability. PMID:25394424

  16. Isostructural solid-solid phase transition in monolayers of soft core-shell particles at fluid interfaces: structure and mechanics.

    Science.gov (United States)

    Rey, Marcel; Fernández-Rodríguez, Miguel Ángel; Steinacher, Mathias; Scheidegger, Laura; Geisel, Karen; Richtering, Walter; Squires, Todd M; Isa, Lucio

    2016-04-21

    We have studied the complete two-dimensional phase diagram of a core-shell microgel-laden fluid interface by synchronizing its compression with the deposition of the interfacial monolayer. Applying a new protocol, different positions on the substrate correspond to different values of the monolayer surface pressure and specific area. Analyzing the microstructure of the deposited monolayers, we discovered an isostructural solid-solid phase transition between two crystalline phases with the same hexagonal symmetry, but with two different lattice constants. The two phases corresponded to shell-shell and core-core inter-particle contacts, respectively; with increasing surface pressure the former mechanically failed enabling the particle cores to come into contact. In the phase-transition region, clusters of particles in core-core contacts nucleate, melting the surrounding shell-shell crystal, until the whole monolayer moves into the second phase. We furthermore measured the interfacial rheology of the monolayers as a function of the surface pressure using an interfacial microdisk rheometer. The interfaces always showed a strong elastic response, with a dip in the shear elastic modulus in correspondence with the melting of the shell-shell phase, followed by a steep increase upon the formation of a percolating network of the core-core contacts. These results demonstrate that the core-shell nature of the particles leads to a rich mechanical and structural behavior that can be externally tuned by compressing the interface, indicating new routes for applications, e.g. in surface patterning or emulsion stabilization.

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

    Science.gov (United States)

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

    2013-01-01

    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 (CF4) 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.

  18. Limit Load and Buckling Analysis for Assessing Hanford Single-Shell Tank Dome Structural Integrity

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Kenneth I.; Deibler, John E.; Julyk, Larry J.; Karri, Naveen K.; Pilli, Siva Prasad

    2012-12-07

    The U.S. Department of Energy, Office of River Protection has commissioned a structural analysis of record (AOR) for the Hanford single shell tanks (SSTs) to assess their structural integrity. The analysis used finite element techniques to predict the tank response to the historical thermal and operating loads. The analysis also addressed the potential tank response to a postulated design basis earthquake. The combined response to static and seismic loads was then evaluated against the design requirements of American Concrete Institute (ACI) standard, ACI-349-06, for nuclear safety-related concrete structures. Further analysis was conducted to estimate the plastic limit load and the elastic-plastic buckling capacity of the tanks. The limit load and buckling analyses estimate the margin between the applied loads and the limiting load capacities of the tank structure. The potential for additional dome loads from waste retrieval equipment and the addition of large dome penetrations to accommodate retrieval equipment has generated additional interest in the limit load and buckling analyses. This paper summarizes the structural analysis methods that were used to evaluate the limit load and buckling of the single shell tanks.

  19. Design, fabrication, and test of lightweight shell structure. [for application to the space tug design

    Science.gov (United States)

    1974-01-01

    A cylindrical shell skirt structure was subjected to a design and analysis study using a wide variety of structural materials and concepts. The design loading, axial compression, and torsion is representative of that expected on a typical space tug skirt section. Structural concepts evaluated included honeycomb sandwich, truss, isogrid, and skin/stringer/frame. The materials considered included a wide variety of structural metals as well as glass, graphite, and boron-reinforced composites. Honeycomb sandwich with aluminum faceskins, honeycomb sandwich with graphite/epoxy faceskins, and aluminum truss with fiberglass meteoroid protection layers were the designs selected for further evaluation. Procurement of materials required for fabrication is reported and the structural test plan and fabrication drawings are included. Construction of the graphite/epoxy faceskins, chem mill of the aluminum faceskins, chem mill of aluminum truss components, and fabrication of the graphite/epoxy honeycomb sandwich development panel is also reported.

  20. Microstructure, chemistry, and electronic structure of natural hybrid composites in abalone shell.

    Science.gov (United States)

    Srot, Vesna; Wegst, Ulrike G K; Salzberger, Ute; Koch, Christoph T; Hahn, Kersten; Kopold, Peter; van Aken, Peter A

    2013-05-01

    The crystal structure and chemical composition at the inorganic/inorganic and inorganic/organic interfaces in abalone shell (genus Haliotis) were investigated using advanced analytical transmission electron microscopy (TEM) methods. Electron energy-loss near-edge structures (ELNES) of Ca-M2,3, C-K, Ca-L2,3, O-K and low-loss EEL spectra acquired from aragonite and calcite are distinctly different. When comparing biogenic with inorganic material for aragonite, only minor differences in C-K fine structures could be detected. The crystal structure of the mineral bridges was confirmed by ELNES experiments. ELNES and energy-filtered TEM (EFTEM) experiments of regular and self-healed interfaces between nacreous aragonite and prismatic calcite reveal relatively rough transitions. In this work, the importance of TEM specimen preparation and specimen damage on structural features is discussed.

  1. 数字化口腔修复(12)--CAD/CAM全瓷嵌体修复楔状缺损(附病例报告)%Digital restorative dentistry and prosthodontics (12)--Restoration of wedge-shaped defect by CAD/CAM all ceramic inlay (case report)

    Institute of Scientific and Technical Information of China (English)

    金地; 姚江武

    2016-01-01

    Objective:The clinical effects were observed on the restoration of wedge-shaped defect teeth by using two lithium silicate inlay by (computer aided design/computer aided manufacturing,CAD/CAM). Method:The clinical case was a patient who had a wedge-shaped defect teeth reached deep below free gingival margin, which was going to restore with all ceramic inlay by CAD/CAM. The clinical effect assessment was made after 6 and 12 months respectively, according to modified USPHS standard. Result:The results in each review stage showed that there were no undesirable effects such as fall off, fracture and cleav-age occurred on inlay. The clinical indexes had up to A class. Conclusion:Better clinical effect can be achieved in treating teeth with wedge-shaped defect using two lithium silicate inlay by CAD/CAM, but the long-term follow-up result still had to be fur-ther observed.%目的:观察计算机辅助设计和制作(CAD/CAM)二矽酸锂全瓷嵌体修复牙颈部缺损的临床疗效。方法:临床病例为1颗牙颈部继发龋坏深达龈下的患牙,采用CAD/CAM全瓷嵌体修复,按照改良的USPHS标准分别进行6个月和1年的临床疗效评价。结果:各个复查阶段:嵌体无脱落,折断、劈裂等不良现象,临床指标均达到A级指标。结论:CAD/CAM嵌体修复牙颈部楔状缺损是一种效果良好的修复方法。

  2. Fluid-structure interaction for nonlinear response of shells conveying pulsatile flow

    Science.gov (United States)

    Tubaldi, Eleonora; Amabili, Marco; Païdoussis, Michael P.

    2016-06-01

    Circular cylindrical shells with flexible boundary conditions conveying pulsatile flow and subjected to pulsatile pressure are investigated. The equations of motion are obtained based on the nonlinear Novozhilov shell theory via Lagrangian approach. The flow is set in motion by a pulsatile pressure gradient. The fluid is modeled as a Newtonian pulsatile flow and it is formulated using a hybrid model that contains the unsteady effects obtained from the linear potential flow theory and the pulsatile viscous effects obtained from the unsteady time-averaged Navier-Stokes equations. A numerical bifurcation analysis employs a refined reduced order model to investigate the dynamic behavior. The case of shells containing quiescent fluid subjected to the action of a pulsatile transmural pressure is also addressed. Geometrically nonlinear vibration response to pulsatile flow and transmural pressure are here presented via frequency-response curves and time histories. The vibrations involving both a driven mode and a companion mode, which appear due to the axial symmetry, are also investigated. This theoretical framework represents a pioneering study that could be of great interest for biomedical applications. In particular, in the future, a more refined model of the one here presented will possibly be applied to reproduce the dynamic behavior of vascular prostheses used for repairing and replacing damaged and diseased thoracic aorta in cases of aneurysm, dissection or coarctation. For this purpose, a pulsatile time-dependent blood flow model is here considered by applying physiological waveforms of velocity and pressure during the heart beating period. This study provides, for the first time in literature, a fully coupled fluid-structure interaction model with deep insights in the nonlinear vibrations of circular cylindrical shells subjected to pulsatile pressure and pulsatile flow.

  3. 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.

  4. Enhancing oxidative stability in heated oils using core/shell structures of collagen and α-tocopherol complex.

    Science.gov (United States)

    Gim, Seo Yeong; Hong, Seungmi; Kim, Jisu; Kwon, YongJun; Kim, Mi-Ja; Kim, GeunHyung; Lee, JaeHwan

    2017-11-15

    In this study, collagen mesh structure was prepared by carrying α-tocopherol in the form of core/shell complex. Antioxidant properties of α-tocopherol loaded carriers were tested in moisture added bulk oils at 140°C. From one gram of collagen core/shell complex, 138mg α-tocopherol was released in medium chain triacylglycerol (MCT). α-Tocopherol was substantially protected against heat treatment when α-tocopherol was complexed in collagen core/shell. Oxidative stability in bulk oil was significantly enhanced by added collagen mesh structure or collagen core/shell complex with α-tocopherol compared to that in control bulk oils (pcore/shell with α-tocopherol (p>0.05). Results of DPPH loss in methanol demonstrated that collagen core/shell with α-tocopherol had significantly (pcore/shell complex is a promising way to enhance the stability of α-tocopherol and oxidative stability in oil-rich foods prepared at high temperature. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. An adaptive piezoelectric vibration absorber enhanced by a negative capacitance applied to a shell structure

    Science.gov (United States)

    Gripp, J. A. B.; Góes, L. C. S.; Heuss, O.; Scinocca, F.

    2015-12-01

    Piezoelectric shunt damping is a well-known technique to damp mechanical vibrations of a structure, using a piezoelectric transducer to convert mechanical vibration energy into electrical energy, which is dissipated in an electrical resistance. Resonant shunts consisting of a resistance and an inductance connected to a piezoelectric transducer are used to damp structural vibrations in narrow frequency bands, but their performance is very sensitive to variations in structural modal frequencies and transducer capacitance. In order to overcome this drawback, a piezoelectric shunt damping technique with improved performance and robustness is presented in this paper. The design of the adaptive circuit considers the variation of the host structure’s natural frequency as a project parameter. This paper describes an adaptive resonant piezoelectric vibration absorber enhanced by a synthetic negative capacitance applied to a shell structure. The resonant shunt circuit autonomously adapts its inductance value by comparing the phase difference of the vibration velocity and the current flowing through the shunt circuit. Moreover, a synthetic negative capacitance is added to the shunt circuit to enhance the vibration attenuation provided by the piezoelectric absorber. The circuitry is implemented using analog components. Validation of the proposed method is done by bonding the piezoelectric absorber on a free-formed metallic shell.

  6. Numerical analysis of stiffened shells of revolution. Volume 4: Engineer's program manual for STARS-2S shell theory automated for rotational structures - 2 (statics) digital computer program

    Science.gov (United States)

    Svalbonas, V.; Ogilvie, P.

    1973-01-01

    The engineering programming information for the digital computer program for analyzing shell structures is presented. The program is designed to permit small changes such as altering the geometry or a table size to fit the specific requirements. Each major subroutine is discussed and the following subjects are included: (1) subroutine description, (2) pertinent engineering symbols and the FORTRAN coded counterparts, (3) subroutine flow chart, and (4) subroutine FORTRAN listing.

  7. 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.

  8. A simple method to prepare titania nanomaterials of core-shell structure, hollow nanospheres and mesoporous nanoparticles

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A simple method to prepare titania nanomaterials of core-shell structure, hollow nanospheres and mesoporous nanoparticles has been developed. The core-shell nanostructures with NH4Cl as core and TiO2·xH2O-NH4Cl as shell were prepared in nonaqueous system by the deposition on the surface of the aggregated NH4Cl crystals, which could be transformed into mesoporous anatase nanoparticles or hollow nanospheres by calcination at 500℃ or extraction with methanol, respectively. The hierarchical mesoporous nanostructures benefited the photocatalytic activities of the resultant titania nanomateri-als, demonstrated by the UV light photodegradation of Methyl Orange.

  9. Hydrophobic core/hydrophilic shell structured mesoporous silica nanospheres: enhanced adsorption of organic compounds from water.

    Science.gov (United States)

    Li, Shuru; Jiao, Xuan; Yang, Hengquan

    2013-01-29

    Inspired by the structure features of micelle, we attempt to synthesize a novel functionalized mesoporous silica nanosphere consisting of a hydrophobic core and a hydrophilic shell. The obtained solid materials were structurally confirmed by N(2) sorption, X-ray diffraction (XRD), and transmission electron microscopy (TEM). Their compositions were characterized by Fourier transfer infrared spectroscopy (FT-IR), solid state NMR, X-ray photoelectron spectroscopy (XPS), and elemental analysis. Its fundamental properties such as dispersibility in water or organic phase, wettability, and adsorption ability toward hydrophobic organics in water were investigated. It was revealed that these important properties could be facilely adjusted through varying structure and composition. In particular, these materials showed much better adsorption ability toward hydrophobic organic molecules in water than conventional monofunctionalized mesoporous materials, owing to possessing the hydrophobic/hydrophilic domain-segregated and hierarchically functionalized mesoporous structures. The intriguing properties would make mesoporous materials more accessible to many important applications, especially in aqueous systems.

  10. 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....

  11. Core–shell and multilayered magnetite nanoparticles—Structural and Mössbauer studies

    Energy Technology Data Exchange (ETDEWEB)

    Kalska-Szostko, B., E-mail: kalska@uwb.edu.pl [Institute of Chemistry, Hurtowa 1, 15-399 Białystok (Poland); Wykowska, U. [Institute of Chemistry, Hurtowa 1, 15-399 Białystok (Poland); Satuła, D. [Faculty of Physics, Lipowa 41, 15-424 Białystok (Poland)

    2014-07-01

    In the paper, we present the effective method of the preparation of nanosized core–shell or multilayered nanoparticles with various layer compositions. Metals like Cu, Ag and Au have been used as a surface or spacer material in magnetite based particles. In further steps, functionalization of obtained nanoparticles was done. The resulting nanoparticles were structurally examined by X-ray diffraction, infra-red spectroscopy, transmission electron microscopy and differential scanning calorimetry. Magnetic properties of the nanoparticles were tested by Mössbauer spectroscopy.

  12. Shell-structure effects on high-pressure Rankine-Hugoniot shock adiabats

    CERN Document Server

    Pain, J C

    2007-01-01

    Rankine-Hugoniot shock adiabats are calculated in the pressure range 1 Mbar-10 Gbar with two atomic-structure models: the atom in a spherical cell and the atom in a jellium of charges. These quantum self-consistent-field models include shell effects, which have a strong impact on pressure and shock velocity along the shock adiabat. Comparisons with experimental data are presented and quantum effects are interpreted in terms of electronic specific heat. A simple analytical estimate for the maximum compression is proposed, depending on initial density, atomic weight and atomic number.

  13. Preparation of Magnetic Hybrid Microspheres with Well-Defined Yolk-Shell Structure

    Directory of Open Access Journals (Sweden)

    Yuan Zhao

    2016-01-01

    Full Text Available A facile and efficient route was reported to prepare a kind of yolk-shell magnetic hybrid microspheres by suspension polymerization and calcinations method. The morphology, structure, and composition of the magnetic microspheres were characterized by FTIR, XRD, TEM, SEM, and TGA analysis. The vibrating-sample magnetometry (VSM results clearly showed that the magnetic particles were superparamagnetic with saturation magnetization of 32.82 emu/g which makes the microcomposites easily controlled by an external magnetic field. The results revealed that the magnetic hybrid microspheres might have important applications in magnetic bioseparation and drug delivery.

  14. 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.

  15. Emergence of cluster structures and collectivity within a no-core shell-model framework

    Science.gov (United States)

    Launey, K. D.; Dreyfuss, A. C.; Draayer, J. P.; Dytrych, T.; Baker, R.

    2014-12-01

    An innovative symmetry-guided concept, which capitalizes on partial as well as exact symmetries that underpin the structure of nuclei, is discussed. Within this framework, ab initio applications of the theory to light nuclei reveal the origin of collective modes and the emergence a simple orderly pattern from first principles. This provides a strategy for determining the nature of bound states of nuclei in terms of a relatively small fraction of the complete shell-model space, which, in turn, can be used to explore ultra-large model spaces for a description of alpha-cluster and highly deformed structures together with the associated rotations. We find that by using only a fraction of the model space extended far beyond current no-core shell-model limits and a long-range interaction that respects the symmetries in play, the outcome reproduces characteristic features of the low-lying 0+ states in 12 C (including the elusive Hoyle state and its 2+ excitation) and agrees with ab initio results in smaller spaces. This is achieved by selecting those particle configurations and components of the interaction found to be foremost responsible for the primary physics governing clustering phenomena and large spatial deformation in the ground-state and Hoyle-state rotational bands of 12 C. For these states, we offer a novel perspective emerging out of no-core shell-model considerations, including a discussion of associated nuclear deformation, matter radii, and density distribution. The framework we find is also extensible to negative-parity states (e.g., the 3-1 state in 12C) and beyond, namely, to the low-lying 0+ states of 8Be as well as the ground-state rotational band of Ne, Mg, and Si isotopes. The findings inform key features of the nuclear interaction and point to a new insight into the formation of highly-organized simple patterns in nuclear dynamics.

  16. Design, fabrication and test of lightweight shell structure. [axial compression loads and torsion stress

    Science.gov (United States)

    Lager, J. R.

    1975-01-01

    A cylindrical shell structure 3.66 m (144 in.) high by 4.57 m (180 in.) diameter was designed using a wide variety of materials and structural concepts to withstand design ultimate combined loading 1225.8 N/cm (700 lb/in.) axial compression and 245.2 N/cm (140 lb/in.) torsion. The overall cylinder geometry and design loading are representative of that expected on a high performance space tug vehicle. The relatively low design load level results in designs that use thin gage metals and fibrous-composite laminates. Fabrication and structural tests of small panels and components representative of many of the candidate designs served to demonstrate proposed fabrication techniques and to verify design and analysis methods. Three of the designs evaluated, honeycomb sandwich with aluminum faceskins, honeycomb sandwich with graphite/epoxy faceskins, and aluminum truss with fiber-glass meteoroid protection layers, were selected for further evaluation.

  17. Core-shell structured nanospheres with mesoporous silica shell and Ni core as a stable catalyst for hydrolytic dehydrogenation of ammonia borane

    Institute of Scientific and Technical Information of China (English)

    Hua; Liu; Changyan; Cao; Ping; Li; Yu; Yu; Weiguo; Song

    2014-01-01

    Core-shell structured nanospheres with mesoporous silica shell and Ni core(denoted as Ni@meso-SiO2) are prepared through a three-step process. Monodispersed Ni precursors are first prepared, and then coated with mesoporous SiO2. Final Ni@meso-SiO2spheres are obtained after calcination. The products are characterized by X-ray powder diffraction, transmission electron microscopy and N2adsorption-desorption methods. These spheres have a high surface area and are well dispersed in water, showing a high catalytic activity with a TOF value of 18.5,and outstanding stability in hydrolytic dehydrogenation of ammonia borane at room temperature.

  18. Adaptive resolution simulation of a biomolecule and its hydration shell: Structural and dynamical properties

    Science.gov (United States)

    Fogarty, Aoife C.; Potestio, Raffaello; Kremer, Kurt

    2015-05-01

    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.

  19. Non-observable nature of the nuclear shell structure. Meaning, illustrations and consequences

    CERN Document Server

    Duguet, T; Holt, J D; Somà, V

    2014-01-01

    The concept of single-nucleon shells constitutes a basic pillar of our understanding of nuclear structure. Effective single-particle energies (ESPEs) introduced by French and Baranger represent the most appropriate tool to relate many-body observables to a single-nucleon shell structure. As briefly discussed in [T. Duguet, G. Hagen, Phys. Rev. C {\\bf 85}, 034330 (2012)], the dependence of ESPEs on one-nucleon transfer probability matrices makes them purely theoretical quantities that "run" with the non-observable resolution scale $\\lambda$ employed in the calculation. 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. State-of-the-art multi-reference 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...

  20. 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.

  1. Interface effect of magnetic properties in Ni nanoparticles with a hcp core and fcc shell structure.

    Science.gov (United States)

    Choo, Seongmin; Lee, Kyujoon; Jo, Younghun; Yoon, Seon-Mi; Choi, Jae-Young; Kim, Jea-Young; Park, Jea-Hoon; Lee, Kyung-Jin; Lee, Jong-Heun; Jung, Myung-Hwa

    2011-07-01

    We have fabricated hexagonal close-packed (hcp) Ni nanoparticles covered by a face-centered cubic (fcc) Ni surface layer by polyol method. The magnetic properties have been investigated as a function of temperature and applied magnetic field. The magnetic behavior reveals that the system should be divided magnetically into three distinct phases with different origins. The fcc Ni phase on the shell contributes to the superparamagnetism through a wide temperature range up to 360 K. The hcp Ni phase at the core is associated with antiferromagnetic nature below 12 K. These observations are in good agreement with the X-ray absorption spectroscopy and magnetic circular dichroism measurements. In our particular case, the unique hcp core and fcc shell structure gives rise to an additional anomaly at 20 K in the zero-field-cooled magnetization curve. Its position is barely affected by the magnetic field but its structure disappears above 30 kOe, showing a metamagnetic transition in the magnetization versus magnetic field curve. This new phase originates from the magnetic exchange at the interface between the hcp and fcc Ni sublattices.

  2. Structural anomalies of fluids: origins in second and higher coordination shells.

    Science.gov (United States)

    Krekelberg, William P; Mittal, Jeetain; Ganesan, Venkat; Truskett, Thomas M

    2008-04-01

    Compressing or cooling a fluid typically enhances its static interparticle correlations. However, there are notable exceptions. Isothermal compression can reduce the translational order of fluids that exhibit anomalous waterlike trends in their thermodynamic and transport properties, while isochoric cooling (or strengthening of attractive interactions) can have a similar effect on fluids of particles with short-range attractions. Recent simulation studies by Yan [Phys. Rev. E 76, 051201 (2007)] on the former type of system and Krekelberg [J. Chem. Phys. 127, 044502 (2007)] on the latter provide examples where such structural anomalies can be related to specific changes in second and more distant coordination shells of the radial distribution function. Here, we confirm the generality of this microscopic picture through analysis, via molecular simulation and integral equation theory, of coordination shell contributions to the two-body excess entropy for several related model fluids which incorporate different levels of molecular resolution. The results suggest that integral equation theory can be an effective and computationally inexpensive tool for assessing, based on the pair potential alone, whether new model systems are good candidates for exhibiting structural (and hence thermodynamic and transport) anomalies.

  3. The role of Argopecten purpuratus shells structuring the soft bottom community in shallow waters of southern Peru

    Science.gov (United States)

    Lomovasky, Betina J.; Gamero, Patricia A.; Romero, Leonardo; Firstater, Fausto N.; Gamarra Salazar, Alex; Hidalgo, Fernando; Tarazona, Juan; Iribarne, Oscar O.

    2015-12-01

    Accumulation of Argopecten purpuratus shells often occurs after El Niño events in shallow waters of Independencia Bay (14°17‧S-76°10‧W; Pisco, Peru). Here we experimentally investigate the effects of their shell accumulation on macrobenthos assemblages in soft bottom, shallow areas of the bay. A field experiment (from May 2006 to May 2007), including four treatments with different coverage levels of empty shells of A. purpuratus, were randomly arranged in: (1) areas devoid of shells ("Empty" treatment: experimental control), (2) 50% of the plot area covered with shells haphazardly distributed over the bottom ("medium" treatment), (3) 100% of the plot area covered with shells, forming a 10 cm valve layer ("full" treatment) and (4) "natural control". We found a total of 124 taxa throughout the experiment. Polychaetes, crustaceans and mollusks were the most abundant groups in "natural controls", dominated by the gastropod Nassarius gayi and the polychaetes Prionospio peruana, Platynereis bicanaliculata and Mediomastus branchiferus. The abundance of individuals (N) and the species richness (S) were higher in the "medium" treatment, but only in one month under positive sea bottom thermal anomalies. Similarity analysis (Bray-Curtis) showed that "natural control", "empty" and "full" treatments were more similar among them than the "medium" treatment. Multidimensional analysis showed no clear species association among treatments and a higher grouping among the samplings of Jun-06, Aug-06 and Nov-06. Our results also showed that the commercial crab Romaleon polyodon and the polyplacophora Tonicia elegans were positively affected by shell accumulations ("medium" treatment), while the limpet Fissurella crassa was negatively affected. Our study shows that directly by changing habitat structure or indirectly by changing sediment characteristics, the addition of scallop shells to the soft bottom can modify the macrobenthic assemblage; however, the seasonal oceanographic

  4. A Facile Method for Synthesizing Dendritic Core–Shell Structured Ternary Metallic Aerogels and Their Enhanced Electrochemical Performances

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Qiurong; Zhu, Chengzhou; Li, Yijing; Xia, Haibing; Engelhard, Mark H.; Fu, Shaofang; Du, Dan; Lin, Yuehe

    2016-11-08

    Currently, three dimensional self-supported metallic structures are attractive for their unique properties of high porosity, low density, excellent conductivity etc. that promote their wide application in fuel cells. Here, for the first time, we report a facile synthesis of dendritic core-shell structured Au/Pt3Pd ternary metallic aerogels via a one-pot self-assembly gelation strategy. The as-prepared Au/Pt3Pd ternary metallic aerogels demonstrated superior electrochemical performances toward oxygen reduction reaction compared to commercial Pt/C. The unique dendritic core-shell structures, Pt3Pd alloyed shells and the cross-linked network structures are beneficial for the electrochemical oxygen reduction reaction performances of the Pt-based materials via the electronic effect, geometric effect and synergistic effect. This strategy of fabrication of metallic hydrogels and aerogels as well as their exceptional properties hold great promise in a variety of applications.

  5. Synthesis, structural characterization and magnetic properties of Fe/Pt core-shell nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Pisane, K. L.; Singh, Sobhit; Seehra, M. S., E-mail: mseehra@wvu.edu [Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506-6315 (United States)

    2015-05-07

    Structural and magnetic properties of Fe/Pt core-shell nanostructure prepared by a sequential reduction process are reported. Transmission electron microscopy shows nearly spherical particles fitting a lognormal size distribution with D{sub o} = 3.0 nm and distribution width λ{sub D} = 0.31. In x-ray diffraction, Bragg lines only from the Pt shell are clearly identified with line-widths yielding crystallite size = 3.1 nm. Measurements of magnetization M vs. T (2 K–350 K) in magnetic fields up to 90 kOe show a blocking temperature T{sub B} = 13 K below which hysteresis loops are observed with coercivity H{sub C} increasing with decreasing T reaching H{sub C} = 750 Oe at 2 K. Temperature dependence of the ac susceptibilities at frequencies f{sub m} = 10 Hz–5 kHz is measured to determine the change in T{sub B} with f{sub m} using the Vogel-Fulcher law. This analysis shows the presence of significant interparticle interaction, the Neel-Brown relaxation frequency f{sub o} = 5.3 × 10{sup 10 }Hz and anisotropy constant K{sub a} = 3.6 × 10{sup 6 }ergs/cm{sup 3}. A fit of the M vs. H data up to H = 90 kOe for T > T{sub B} to the modified Langevin function taking particle size distribution into account yields magnetic moment per particle consistent with the proposed core-shell structure; Fe core of 2.2 nm diameter and Pt shell of 0.4 nm thickness.

  6. On the impact of radiation pressure on the dynamics and inner structure of dusty wind-driven shells

    CERN Document Server

    Martinez-Gonzalez, Sergio; Tenorio-Tagle, Guillermo

    2014-01-01

    Massive young stellar clusters are strong sources of radiation and mechanical energy. Their powerful winds and radiation pressure sweep-up interstellar gas into thin expanding shells which trap the ionizing radiation produced by the central clusters affecting the dynamics and the distribution of their ionized gas. Here we continue our comparison of the star cluster winds and radiation pressure effects on the dynamics of shells around young massive clusters. We calculate the impact that radiation pressure has on the distribution of matter and thermal pressure within such shells as well as on the density weighted ionization parameter $U_w$ and put our results on the diagnostic diagram which allows one to discriminate between the wind-dominated and radiation-dominated regimes. We found that model predicted values of the ionization parameter agree well with typical values found in local starburst galaxies. Radiation pressure may affect the inner structure and the dynamics of wind-driven shells only at the earlies...

  7. Versatile Core-Shell Nanoparticle@Metal-Organic Framework Nanohybrids: Exploiting Mussel-Inspired Polydopamine for Tailored Structural Integration.

    Science.gov (United States)

    Zhou, Jiajing; Wang, Peng; Wang, Chenxu; Goh, Yi Ting; Fang, Zheng; Messersmith, Phillip B; Duan, Hongwei

    2015-07-28

    We report a versatile strategy based on the use of multifunctional mussel-inspired polydopamine for constructing well-defined single-nanoparticle@metal-organic framework (MOF) core-shell nanohybrids. The capability of polydopamine to form a robust conformal coating on colloidal substrates of any composition and to direct the heterogeneous nucleation and growth of MOFs makes it possible for customized structural integration of a broad range of inorganic/organic nanoparticles and functional MOFs. Furthermore, the unique redox activity of polydopamine adds additional possibilities to tailor the functionalities of the nanohybrids by sandwiching plasmonic/catalytic metal nanostructures between the core and shell via localized reduction. The core-shell nanohybrids, with the molecular sieving effect of the MOF shell complementing the intrinsic properties of nanoparticle cores, represent a unique class of nanomaterials of considerable current interest for catalysis, sensing, and nanomedicine.

  8. The Three-dimensional Structure of the Cassiopeia A Supernova Remnant. I. The Spherical Shell

    Science.gov (United States)

    Reed, Jeri E.; Hester, J. Jeff; Fabian, A. C.; Winkler, P. F.

    1995-02-01

    The three-dimensional structure of the Cassiopeia A supernova remnant is explored via 73 long-slit optical spectra (spanning 6250-7600 Å) which cross the face and "jet" region of the nebula. We extracted position, radial velocity, and line intensity information from nearly 25,000 cross sections of these original data, resulting in a library of 3663 fast-moving knots (FMKs) and 450 quasi-stationary flocculi (QSFs) detections. We performed an iterative least-squares spherical fit to the data, using this to convert radial velocities to line-of-sight distances. We have built up a picture of the remnant as a spherical circumstellar shell of 104"5±0"7 radius, corresponding to 5.3 × 1018 cm (1.7 pc). The center on the sky is displaced by 8".7 west and 12".6 north of the proper motion center. The velocity center of our fitted sphere has been redshifted by 770±40 km s-1 from the presumed expansion center at zero velocity. This expansion of the ejecta from a displaced center accounts for the observed radial velocity difference at the front and back faces. The average rate of expansion of the FMKs is 5290±90 km s-1, while the asymmetric values are 4520 km s-1 at the blueshifted face, and 6060 km s-1 at the redshifted face. Based on a comparison of our suite of radial velocities with all the available proper-motion and age data, we find the distance to Cas A to be 3.4+0.3-0.1 kpc. Our kinematic analysis shows the optically emitting ejecta of Cas A have been slowed certainly by less than 7%, and probably by less than 4% and that the velocity of the reverse shock driven into the knots is about 200 km s-1. We conclude that the center of expansion of the supernova is displaced by about 0.36 pc (1.1 × 1018 cm) to the northwest and front of the geometric center of the bubble. The geometry suggests that the density of the surrounding medium is greater in the direction of displacement. The asymmetrically distributed radial velocities of the QSFs, of which 76% are blueshifted

  9. LOAD CARRYING CAPABILITY OF LIQUID FILLED CYLINDRICAL SHELL STRUCTURES UNDER AXIAL COMPRESSION

    Directory of Open Access Journals (Sweden)

    QASIM H. SHAH

    2011-08-01

    Full Text Available Empty and water filled cylindrical Tin (Sn coated steel cans were loaded under axial compression at varying loading rates to study their resistance to withstand accidental loads. Compared to empty cans the water filled cans exhibit greater resistance to axially applied compression loads before a complete collapse. The time and load or stroke and load plots showed three significant load peaks related to three stages during loading until the cylinder collapse. First peak corresponds to the initial structural buckling of can. Second peak occurs when cylindrical can walls gradually come into full contact with water. The third peak shows the maximum load carrying capability of the structure where pressurized water deforms the can walls into curved shape until can walls fail under peak pressure. The collapse process of water filled cylindrical shell was further studied using Smooth Particle Hydrodynamics (SPH technique in LSDYNA. Load peaks observed in the experimental work were successfully simulated which substantiated the experimental work.

  10. Origin of fine structure of the giant dipole resonance in sd-shell nuclei

    CERN Document Server

    Fearick, R W; Matsubara, H; von Neumann-Cosel, P; Richter, A; Roth, R; Tamii, A

    2014-01-01

    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 sd-shell nuclei. Understanding is provided by state-of-the-art theoretical Random Phase Approximation (RPA) calculatios 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 to extract significant scales both in the data and calculations characterizing the fine structure of the GDR. The fair agreement supports that the fine structure arises from ground-state deformation driven by alpha clustering.

  11. Load requirements for maintaining structural integrity of Hanford single-shell tanks during waste feed delivery and retrieval activities

    Energy Technology Data Exchange (ETDEWEB)

    JULYK, L.J.

    1999-09-22

    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.

  12. Systematic position, distribution, and shell structure of the Devonian linguloid brachiopod Bicarinatina bicarinata (Kutorga, 1837

    Directory of Open Access Journals (Sweden)

    Puura, Ivar

    2009-03-01

    Full Text Available The type species of the brachiopod genus Bicarinatina Batrukova was first described by Kutorga in 1837 (Zweiter Beitrag zur Geognosie und Paläaontologie Dorpats und seiner nächsten Umbegebungen. St.-Petersbourg, 51 pp. as Lingula bicarinata from the Middle Devonian sandstone beds now assigned to the Aruküla Regional Stage in Tartu, Estonia. Gravitis (1981, in Devon i karbon pribaltiki (Brangulis et al., eds, pp. 455–462. Zinatne, Riga described eight new species of the genus Bicarinatina. Revision of the collections in St Petersburg and Riga showed that four of these species names should be considered as subjective junior synonyms of the type species Bicarinatina bicarinata (Kutorga and that the type specimens of the remaining four new species were either juvenile or too poorly preserved for species-level identifications. Therefore, B. bicarinata should be considered the only valid species of the genus Bicarinatina occurring in the Middle Devonian on the Baltic plate, known from Estonia, Latvia, and northwestern Russia. The shell structure of B. bicarinata is baculate symmetrical, with the finest baculate sets in the innermost parts of the valves and thicker and aggregated baculi in outer parts, due to stronger taphonomic changes in outer parts of the shell. In cross section, the valves are 70–100 µm thick.

  13. 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.

  14. Shell Structure from 100Sn to 78Ni: Implications for Nuclear Astrophysics

    Energy Technology Data Exchange (ETDEWEB)

    Grawe, Hubert H [ORNL; Blazhev, A. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Gorska, M. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Mukha, I. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Plettner, C. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Roeckl, E. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Nowacki, F. [IReS, Strasbourg, Cedex, France; Grzywacz, Robert Kazimierz [ORNL; Sawicka, M. [University of Warsaw

    2005-09-01

    The single-particle structure and shell gap of {sup 100}Sn is inferred from prompt in-beam and delayed {gamma}-ray spectroscopy of seniority and spin-gap isomers. Recent results in {sup 94, 95}Ag and {sup 98}Cd stress the importance of large-scale shell model calculations employing realistic interactions for the isomerism, np-nh excitations and E2 polarization of the {sup 100}Sn core. The strong monopole interaction of the {Delta}l = 0 spin-flip partners {pi}g{sub 9/2-} {nu}g{sub 7/2} in N = 51 isotones below {sup 100}Sn is echoed in the {Delta}l = 1 pf5/2- ?g9/2 pair of nucleons, which is decisive for the persistence of the N = 50 shell gap in {sup 78}Ni. This is corroborated by recent experimental data on {sup 70, 76}Ni, {sup 78}Zn. The importance of monopole driven shell evolution for the appearance of new shell closures in neutron-rich nuclei and implications for r-process abundances near the N = 82 shell is discussed.

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

    Science.gov (United States)

    Cheng, Hai-Xia; Wang, Xiao-Xu; Hu, Yao-Wen; Song, Hong-Quan; Huo, Jin-Rong; Li, Lu; Qian, Ping; Song, Yu-Jun

    2016-12-01

    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.

  16. Investigation of fine-structure dips in fission-fragment mass distribution: An asymmetric two centre shell model approach

    Science.gov (United States)

    Malik, Sham S.

    2017-04-01

    The fission fragment mass distribution followed by neutron emission is studied for the 208Pb (18O , f) reaction using the asymmetric two centre shell model. The measured mass distribution spectrum reveals new kind of systematics on shell structure and leads to an improved understanding of structure effects in nuclear fission. A detailed investigation of shell effects both in potential and cranking mass parameter has been carried out for explaining the observed fine structure dips (i.e., less probable distributions) corresponding to shell closure (Z = 50 and/or N = 82) of fission fragments and their complementary partners. The available energy states for the decay process are obtained by solving the Schrödinger equation and found that first-five eigenstates are sufficient in reproducing the observed mass distribution spectrum. An outcome of the asymmetric two centre shell model also completely favours the observed claim that ;the total number of emitted neutrons between correlated pairs of fission fragments should not exceed 6;. A complete observed spectrum is obtained by adding the mass distribution yields of all 6-neutron emission channels. This suggests a possible importance of extending these calculations to get new insight into an understanding of the dynamical behaviour of fragment formation in the fission process.

  17. Physical mechanism of surface roughening of the radial Ge-core/Si-shell nanowire heterostructure and thermodynamic prediction of surface stability of the InAs-core/GaAs-shell nanowire structure.

    Science.gov (United States)

    Cao, Y Y; Ouyang, G; Wang, C X; Yang, G W

    2013-02-13

    As a promising and typical semiconductor heterostructure at the nanoscale, the radial Ge/Si NW heterostructure, that is, the Ge-core/Si-shell NW structure, has been widely investigated and used in various nanodevices such as solar cells, lasers, and sensors because of the strong changes in the band structure and increased charge carrier mobility. Therefore, to attain high quality radial semiconductor NW heterostructures, controllable and stable epitaxial growth of core-shell NW structures has become a major challenge for both experimental and theoretical evaluation. Surface roughening is usually undesirable for the epitaxial growth of high quality radial semiconductor NW heterostructures, because it would destroy the core-shell NW structures. For example, the surface of the Ge-core/Si-shell NWs always exhibits a periodic modulation with island-like morphologies, that is, surface roughening, during epitaxial growth. Therefore, the physical understanding of the surface roughening behavior during the epitaxial growth of core-shell NW structures is essential and urgent for theoretical design and experimentally controlling the growth of high quality radial semiconductor NW heterostructures. Here, we proposed a quantitative thermodynamic theory to address the physical process of epitaxial growth of core-shell NW structures and surface roughening. We showed that the transformation from the Frank-van der Merwe mode to the Stranski-Krastanow mode during the epitaxial growth of radial semiconductor NW heterostructures is the physical origin of surface roughening. We deduced the thermodynamic criterion for the formation of the surface roughening and the phase diagram of growth and showed that the radius of the NWs and the thickness of the shell layer can not only determine the formation of the surface roughening in a core-shell NW structure, but also control the periodicity and amplitude of the surface roughness. The agreement between the theoretical results and the

  18. Nuclear structure of low-lying states in 60,62,64,66Zn — A shell model description

    Science.gov (United States)

    Rai, S.; Biswas, A.; Mukherjee, B.

    2016-11-01

    Shell model calculation has been performed for even-even 60,62,64,66Zn using NuShellX code in f5/2pg9/2 model space with two different effective Hamiltonians, viz. JUN45 and jj44b. The low-lying structure is studied up to angular momentum, I = 10ℏ by calculating level energies, reduced transition probabilities, occupation numbers, lifetimes, and quadrupole moments. The results of the calculations are compared with the available experimental data. It is observed that the inclusion of 1g9/2 orbital in the model space is essential to understand nuclear structure in these isotopes. Shell model calculation with an improved set of effective Hamiltonian parameters and inclusion of 1f7/2 orbital in the model space are necessary in order to produce finer agreement with the experimental observations.

  19. A novel approach to the systematization of α-decaying nuclei, based on shell structures

    Science.gov (United States)

    Yarman, Tolga; Zaim, Nimet; Amon Susam, Lidya; Kholmetskii, Alexander; Arık, Metin; Azmi Altıntaş, Ali; Ozaydin, Fatih

    2016-05-01

    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.

  20. Shell structure in neutron rich nuclei by means of binary reactions

    Energy Technology Data Exchange (ETDEWEB)

    Angelis, G. de [INFN, Laboratori Nazionali di Legnaro (Italy)

    2014-08-14

    Nuclear structure studies far from stability rely mainly on the availability of radioactive nuclear beams but can complementary be addressed by means of high intensity beams of stable ions. In such contest, deep-inelastic and multinucleon transfer reactions are a powerful tool to populate yrast and non yrast states in neutron-rich nuclei. Particularly successful is here the combination of large acceptance spectrometers with highly segmented gamma-detector arrays. Such devices can provide the necessary channel selectivity to identify very rare signals. The AGATA gamma-ray detector array coupled to the PRISMA spectrometer at the Legnaro National Laboratories (LNL) in Italy is one example. Large data sets have been collected at LNL for nuclei close to the N=20, 28, 40, 50 and 82 shell closures.

  1. Shell Model for Elastic and Thermodynamic Properties of Gallium Nitride with Hexagonal Wurtzite Structure

    Institute of Scientific and Technical Information of China (English)

    CHENG Yan; TU Ya-Jing; ZENG Zhao-Yi; GOU Qing-Quan

    2008-01-01

    Shell model molecular dynamic simulation with interatomic pair potential is utilized to investigate the elastic and thermodynamic properties of gallium nitride with hexagonal wurtzite structure (w-GaN) at high pressure. The calculated elastic constants Cij at zero pressure and 300 K agree well with the experimental data and other calculated values. Meanwhile, the dependences of the relative volume V/Vo, elastic constants Cij, entropy S, enthalpy H, and heat capacities Cv and Cp on pressure are successfully obtained. From the elastic constants obtained, we also calculate the shear modulus G, bulk modulus B, Young's modulus E, Poisson's ratio v, Debye temperature ΘD, and shear anisotropic factor Ashear on pressures.

  2. Accelerated safety analyses - structural analyses Phase I - structural sensitivity evaluation of single- and double-shell waste storage tanks

    Energy Technology Data Exchange (ETDEWEB)

    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.

  3. Controllable preparation of hierarchically core–shell structure NiO/C microspheres for non-enzymatic glucose sensor

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Zhenzhen; Yin, Haoyong; Nie, Qiulin, E-mail: nieqiulin@hdu.edu.cn

    2015-05-25

    Highlights: • Hierarchically core–shell structure NiO/C microspheres were prepared. • The NiO/C microspheres were obtained via layer-by-layer assembly methods. • The NiO/C sensor shows excellent performance in glucose detection. • Good stability and anti-interference were also obtained on the NiO/C sensor. - Abstract: Hierarchically core–shell structure NiO/C microspheres were controllably fabricated with a facile hydrothermal method via layer-by-layer assembly. The single-/double-/triple-/quadri-shelled NiO/C microspheres were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), and energy dispersive X-ray spectroscopy (EDX). The results showed that the NiO/C composites are flower-like hierarchically structured microspheres composed of the interconnecting porous nanoplates with the thickness of about 50 nm. Every nanoplate is assembled by NiO nanoparticles with diameter about 10 nm. All the multi-shelled NiO/C microspheres show high electro-catalytic activity toward the oxidation of glucose. The double-shelled NiO/C glucose sensor exhibits the best performance with a much wider linear range of 2 μM–1.279 mM, higher sensitivity of 30.19 mA mM{sup −1} cm{sup −2} and lower detection limit of 2 μM. Importantly, long-term stability and favorable anti-interference were obtained thanks to the hierarchically core–shell structure.

  4. Core-shell structured titanium-nitrogen alloys with high strength, high thermal stability and good plasticity.

    Science.gov (United States)

    Zhang, Y S; Zhao, Y H; Zhang, W; Lu, J W; Hu, J J; Huo, W T; Zhang, P X

    2017-01-06

    Multifunctional materials with more than two good properties are widely required in modern industries. However, some properties are often trade-off with each other by single microstructural designation. For example, nanostructured materials have high strength, but low ductility and thermal stability. Here by means of spark plasma sintering (SPS) of nitrided Ti particles, we synthesized bulk core-shell structured Ti alloys with isolated soft coarse-grained Ti cores and hard Ti-N solid solution shells. The core-shell Ti alloys exhibit a high yield strength (~1.4 GPa) comparable to that of nanostructured states and high thermal stability (over 1100 °C, 0.71 of melting temperature), contributed by the hard Ti-N shells, as well as a good plasticity (fracture plasticity of 12%) due to the soft Ti cores. Our results demonstrate that this core-shell structure offers a design pathway towards an advanced material with enhancing strength-plasticity-thermal stability synergy.

  5. Core-shell structured titanium-nitrogen alloys with high strength, high thermal stability and good plasticity

    Science.gov (United States)

    Zhang, Y. S.; Zhao, Y. H.; Zhang, W.; Lu, J. W.; Hu, J. J.; Huo, W. T.; Zhang, P. X.

    2017-01-01

    Multifunctional materials with more than two good properties are widely required in modern industries. However, some properties are often trade-off with each other by single microstructural designation. For example, nanostructured materials have high strength, but low ductility and thermal stability. Here by means of spark plasma sintering (SPS) of nitrided Ti particles, we synthesized bulk core-shell structured Ti alloys with isolated soft coarse-grained Ti cores and hard Ti-N solid solution shells. The core-shell Ti alloys exhibit a high yield strength (~1.4 GPa) comparable to that of nanostructured states and high thermal stability (over 1100 °C, 0.71 of melting temperature), contributed by the hard Ti-N shells, as well as a good plasticity (fracture plasticity of 12%) due to the soft Ti cores. Our results demonstrate that this core-shell structure offers a design pathway towards an advanced material with enhancing strength-plasticity-thermal stability synergy.

  6. Integrated Topology Optimization of Structure/Vibration Control for Piezoelectric Cylindrical Shell Based on the Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    Jianjun He

    2015-01-01

    Full Text Available A hybrid optimization strategy for integrated topological optimization design of piezoelectric cylindrical flat shell structure is proposed. The method combines the genetic algorithm (GA and linear-quadratic-regulator (LQR theory to optimize the performance of coupling structure/control system. The GA is used to choose the optimal structure topology and number and placements of actuators and control parameters; meanwhile, the LQR is used to design control system to suppress vibration of optimal structure under sinusoidal excitation, which is based on the couple-mode space control. In addition, the mathematical morphology operators are used for repairs of disconnected structure topology. The results of numerical simulation and computations show that the proposed method is effective and feasible, with good performance for the optimal and coupling piezoelectric cylindrical shell structure/control system.

  7. Isolation and Structural Characterization of a Mackay 55-Metal-Atom Two-Shell Icosahedron of Pseudo-Ih Symmetry, Pd55L12(μ3-CO)20 (L = PR3, R = Isopropyl): Comparative Analysis with Interior Two-Shell Icosahedral Geometries in Capped Three-Shell Pd145, Pt-Centered Four-Shell Pd-Pt M165, and Four-Shell Au133 Nanoclusters.

    Science.gov (United States)

    Erickson, Jeremiah D; Mednikov, Evgueni G; Ivanov, Sergei A; Dahl, Lawrence F

    2016-02-10

    We present the first successful isolation and crystallographic characterization of a Mackay 55-metal-atom two-shell icosahedron, Pd55L12(μ3-CO)20 (L = PPr(i)3) (1). Its two-shell icosahedron of pseudo-Ih symmetry (without isopropyl substituents) enables a structural/bonding comparison with interior 55-metal-atom two-shell icosahedral geometries observed within the multi-shell capped 145-metal-atom three-shell Pd145(CO)72(PEt3)30 and 165-metal-atom four-shell Pt-centered (μ12-Pt)Pd164-xPtx(CO)72(PPh3)20 (x ≈ 7) nanoclusters, and within the recently reported four-shell Au133(SC6H4-p-Bu(t))52 nanocluster. DFT calculations carried out on a Pd55(CO)20(PH3)12 model analogue, with triisopropyl phosphine substituents replaced by H atoms, revealed a positive +0.84 e charge for the entire Pd55 core, with a highly positive second-shell Pd42 surface of +1.93 e.

  8. Helical Shell Structures of Ni-Al Alloy Nanowires and Their Electronic Transport Properties

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xue-Qing; LI Hui; LIEW Kim-Meow; LI Yun-Fang; SUN Feng-Wei

    2007-01-01

    Six kinds of Ni-Al alloy nanowires are optimized by means of simulated annealing. The optimized structures show that the Ni-Al alloy nanowires are helical shell structures that are wound by three atomic strands, which is very similar to the case with pure metallic nanowires. The densities of states (DOS), transmission function T(E), current-voltage (Ⅰ-Ⅴ) curves, and the conductance spectra of these alloy nanowires are also investigated. Our results indicate that the conductance spectra depend on the geometric structure properties and the ingredients of the alloy nanowires. We observe and study the nonlinear contribution to the Ⅰ-Ⅴ characteristics that are due to the quantum size effect and the impurity effect. The addition of Ni atoms decreases the conductance of the Ni-Al alloy nanowire because the doping atom Ni change the electronic band structures and the charge density distribution. The interesting statistical results shed light on the physics of quantum transport at the nano-scale.

  9. 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.

  10. Observation of Clinical Therapeutic Effect of Combination of Glass Gonomer Gement and Light Cured Composite Resin on Restoring Wedge Shaped Defect%两种材料联合修复牙齿楔状缺损的临床疗效观察

    Institute of Scientific and Technical Information of China (English)

    戴晓枫

    2012-01-01

    Objective To evaluate clinical therapeutic effect of combination of glass ionomer cement and light cured composite resin on restoring wedge shaped defect. Methods 110 teeth with wedge shaped defects in treatment group were filled and repaired with glass ionomer cement. The light cured composite resin was used to repair the teeth permanently after 24 hours. The other two control groups were treated with glass ionomer cement and light cured composite resin respectively. The treatment results and cure rates were compared between the three groups after one year follow-up. Results The cure rates of treatment group and two control groups were 98.61%, 77.85%, 77.46% respectively. The difference between treatment group and control groups was significant (p<0.01). Conclusion The combination of glass ionomer cement and light cured composite resin is a better method to restore the wedge shaped defect.%目的探讨玻璃离子水门汀联合光固化复合树脂充填修复牙齿楔状缺损的临床疗效.方法对110例楔状缺损患牙采用玻璃离子水门汀常规充填雕刻成形,然后行光固化复合树脂永久修复.对照组分别用玻璃离子、光固化复合树脂.随访一年后比较3组修复楔状缺损治愈率.结果两种材料联合修复牙齿楔状缺损的治愈率98.61%,对照组的治愈率77.85%和77.46%;两组有显著差异(P<0.01).结论两种材料联合修复牙齿楔状缺损技术是理想方法之一.

  11. Limit Load and Buckling Analysis for Assessing Hanford Single-Shell Tank Dome Structural Integrity - 12278

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Ken I.; Deibler, John E.; Karri, Naveen K.; Pilli, Siva P. [Pacific Northwest National Laboratory, Richland, Washington 99352 (United States); Julyk, Larry J. [M and D Professional Services, Inc., Richland, Washington 99352 (United States)

    2012-07-01

    The U.S. Department of Energy, Office of River Protection has commissioned a structural analysis of record for the Hanford single shell tanks to assess their structural integrity. The analysis used finite element techniques to predict the tank response to the historical thermal and operating loads. The analysis also addressed the potential tank response to a postulated design basis earthquake. The combined response to static and seismic loads was then evaluated against the design requirements of American Concrete Institute standard, ACI-349-06, for nuclear safety-related concrete structures. Further analysis was conducted to estimate the plastic limit load and the elastic-plastic buckling capacity of the tanks. The limit load and buckling analyses estimate the margin between the applied loads and the limiting load capacities of the tank structure. The potential for additional dome loads from waste retrieval equipment and the addition of large dome penetrations to accommodate retrieval equipment has generated additional interest in the limit load and buckling analyses. This paper summarizes the structural analysis methods that were used to evaluate the limit load and buckling of the single shell tanks. This paper summarizes the structural analysis methods that were used to evaluate the limit load and buckling limit states of the underground single shell tanks at the Hanford site. The limit loads were calculated using nonlinear finite element models that capture the progressive deformation and damage to the concrete as it approaches the limit load. Both uniform and concentrated loads over the tank dome were considered, and the analysis shows how adding a penetration in the center of the tank would affect the limit loads. For uniform surface loads, the penetration does not affect the limit load because concrete crushing and rebar yielding initiates first at the top of the wall, away from the penetration. For concentrated loads, crushing initiates at the center of the

  12. 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.

  13. Surface corrections to the shell-structure of the moment of inertia

    CERN Document Server

    Gorpinchenko, D V; 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 Inglis cranking and the Strutinsky shell-correction methods, improved by surface corrections within the non-perturbative periodic-orbit theory. For adiabatic (statistical-equilibrium) rotations it was approximated by the generalized rigid-body moment of inertia accounting for the shell corrections of the particle density. An improved phase-space trace formula allows to express the shell components of the moment of inertia more accurately in terms of the free-energy shell correction with their ratio evaluated within the extended Thomas-Fermi effective-surface approximation.

  14. 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.

  15. On the structure of Ce-containing silicophosphate glasses: a core-shell molecular dynamics investigation.

    Science.gov (United States)

    Gambuzzi, Elisa; Pedone, Alfonso

    2014-10-21

    Classical molecular dynamics simulations have been used to investigate the local and medium range structure of Ce-containing silicophosphate glasses widely used in optical and photonic devices because of their enhanced UV absorption and radiation damage resistance properties. New Ce(3+)-O and Ce(4+)-O parameters for a force-field based on the core-shell model were developed by fitting on the crystalline structures of Ce-containing crystal phases, and used to get insights into the structure of five silicophosphate glasses with increasing Ce2O3 and P2O5 content. An excellent agreement between experimental and computational data was found for the local environment around cerium ions and network former cations. The Ce(3+)-O bond lengths are generally longer than Ce(4+)-O, which shows higher coordination numbers. Both P and Si are four-fold coordinated; their allocation in the network is not uniform: the increasing Ce content leads to the formation of silica-rich domains and phosphate-rich domains, which entrap Ce cations increasing their solubility in the glass. We found that both the Q(n) distributions of phosphorous and Ce clustering depend on the Ce/P ratio in the glass. In particular, Ce clustering begins for Ce/P ratios between 0.17 and 0.29 in the glass series investigated.

  16. 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.

  17. Cross-sectional mapping for refined beam elements with applications to shell-like structures

    Science.gov (United States)

    Pagani, A.; de Miguel, A. G.; Carrera, E.

    2017-02-01

    This paper discusses the use of higher-order mapping functions for enhancing the physical representation of refined beam theories. Based on the Carrera unified formulation (CUF), advanced one-dimensional models are formulated by expressing the displacement field as a generic expansion of the generalized unknowns. According to CUF, a novel physically/geometrically consistent model is devised by employing Legendre-like polynomial sets to approximate the generalized unknowns at the cross-sectional level, whereas a local mapping technique based on the blending functions method is used to describe the exact physical boundaries of the cross-section domain. Classical and innovative finite element methods, including hierarchical p-elements and locking-free integration schemes, are utilized to solve the governing equations of the unified beam theory. Several numerical applications accounting for small displacements/rotations and strains are discussed, including beam structures with cross-sectional curved edges, cylindrical shells, and thin-walled aeronautical wing structures with reinforcements. The results from the proposed methodology are widely assessed by comparisons with solutions from the literature and commercial finite element software tools. The attention is focussed on the high computational efficiency and the marked capabilities of the present beam model, which can deal with a broad spectrum of structural problems with unveiled accuracy in terms of geometrical representation of the domain boundaries.

  18. Structural stability of alloyed and core-shell Cu-Pt bimetallic nanoparticles

    Science.gov (United States)

    Peng, Hongcheng; Qi, Weihong; Ji, Wenhai; Li, Siqi; He, Jieting

    2017-03-01

    Combining the bond-energy model and Debye theory, we generalized the Gibbs free energy model for Cu-Pt nanoparticles (NPs) by introducing a shape factor considering the shape effect. We studied the structural stability of the Cu-Pt NPs and plotted the corresponding composition-, shape- and size-dependent phase diagrams. It is shown that the Cu-Pt NPs can form alloyed structure in a large size range. But when the particle size continues to decrease, the NPs will form the core-shell structure due to surface segregation. Meanwhile, the composition segregation could make the atoms of less-content element to gather in the surface. The predictions from the present calculated phase diagrams are consistent with a series of experimental results in literatures. To further prove the efficiency of the phase diagrams, we synthesized the alloyed Cu-Pt NPs of 4-15 nm by a co-reduction method, which is in agreement with the predictions from the phase diagrams.

  19. Molecular dynamics study of crater formation by core-shell structured cluster impact

    Science.gov (United States)

    Aoki, Takaaki; Seki, Toshio; Matsuo, Jiro

    2012-07-01

    Crater formation processes by the impacts of large clusters with binary atomic species were studied using molecular dynamics (MD) simulations. Argon and xenon atoms are artificially organized in core-shell cluster structures with various component ratios and irradiated on a Si(1 0 0) target surface. When the cluster has Xe1000 core covered with 1000 Ar atoms, and impacts at a total of 20 keV, the core Xe cluster penetrates into the deep area, and a crater with a conical shape is left on the target. On the other hand, in the case of a cluster with the opposite structure, Ar1000 core covered with 1000 Xe atoms, the cluster stops at a shallow area of the target. The incident cluster atoms are mixed and tend to spread in a lateral direction, which results in a square shaped crater with a shallower hole and wider opening. The MD simulations suggest that large cluster impacts cause different irradiation effects by changing the structure, even if the component ratio is the same.

  20. Chaotic interaction dynamics of three structures: Two cylindrical shells nested into each other and their reinforcing local rib

    Science.gov (United States)

    Krysko, V. A.; Vetsel', S. S.; Dobriyan, V. V.; Saltykova, O. A.

    2017-05-01

    This paper studies the chaotic dynamics of two cylindrical shells nested into each other with a gap and their reinforcing beam, also with a gap, which is subjected to a distributed alternating load. The problem is solved using methods of nonlinear dynamics and the qualitative theory of differential equations. The Novozhilov equations for geometrically nonlinear structures are used as the governing equations. Contact pressure is determined by Kantor's method. Using finite elements in spatial variables, the partial differential equations for the beam and shells are reduced to the Cauchy problem, which is solved by explicit integration (Euler's method). The chaotic synchronization of this system is studied.

  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. Structural and optical investigation of semiconductor CdSe/CdS core-shell quantum dot thin films.

    Science.gov (United States)

    Sharma, A B; Sharma, Sudhir Kumar; Sharma, M; Pandey, R K; Reddy, D S

    2009-03-01

    Highly luminescent CdSe/CdS core-shell nanocrystals have been assembled on indium tin oxide (ITO) coated glass substrates using a wet synthesis route. The physical properties of the quantum dots (QD) have been investigated using X-ray diffraction, transmission electron microscopy and optical absorption spectroscopy techniques. These quantum dots showed a strong enhancement in the near band edge absorption. The in situ luminescence behavior has been interpreted in the light of the quantum confinement effect and induced strain in the core-shell structure.

  3. A simple method to prepare titania nanomaterials of core-shell structure,hollow nanospheres and mesoporous nanoparticles

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hui; LI DeQian; SHAO GaoSong; YUAN ZhongYong

    2009-01-01

    A simple method to prepare titania nanomaterials of core-shell structure,hollow nanospheres and mesoporous nanoparticlee has been developed.The core-shell nanostructures with NH4CI as core and aggregated NH4Cl crystals,which could be transformed into mesoporous anatase nanoparticles or hollow nanospheres by calcination at 500℃ or extraction with methanol,respectively.The hierarchical mesoporous nanostructures benefited the photocatalytic activities of the resultant titania nanomaterials,demonstrated by the UV light photodegradation of Methyl Orange.

  4. Computation of wind-induced vibrations of flexible shells and membranous structures

    Science.gov (United States)

    Glück, M.; Breuer, M.; Durst, F.; Halfmann, A.; Rank, E.

    2003-04-01

    A partitioned coupling approach for time-dependent fluid-structure interactions is applied to thin shells and membranous structures with large displacements. The frame algorithm connects a three-dimensional, finite volume-based multi-block flow solver for incompressible fluids with a finite element code for geometrically nonlinear structural problems using a commercial coupling interface. Thus a high modularity is achieved and the whole range of opportunities with these two powerful codes - each of them highly adapted to its specific field of application - can be used also for coupled simulations. Two completely different configurations were investigated. First, the coupling algorithm was applied to an academic test configuration consisting of one, two, and three flexible L-shaped plates being loaded by a steady far-field flow. Various investigations were carried out at different Reynolds numbers /(Re=50,200, and 500) in order to study phenomena such as vortex shedding, resonance, influence of the interaction between several flexible plates, whereas the second and third plates were placed in the wake of the first. The second part of the paper shows that in principle the coupling procedure can also deal with real-life structures as they occur in civil engineering. A membranous roof of glass-fiber synthetics with a complex shape was exposed to a time-dependent wind gust from diagonally above which was superimposed on a constant basic wind flow parallel to the ground. The structural model contains the pre-stressed textile roof including the taut cables at its circumference which are fastened at the pylons. As a structural response, the wind gust led to a displacement of the textile roof which disappeared again when the gust subsided. With the coupled algorithm proposed in the paper it is possible to study dynamic interactions for engineering applications.

  5. Size dependent structural, vibrational and magnetic properties of BiFeO3 and core-shell structured BiFeO3@SiO2 nanoparticles

    Science.gov (United States)

    Chauhan, Sunil; Kumar, Manoj; Chhoker, Sandeep; Katyal, S. C.

    2014-04-01

    Bulk BiFeO3, BiFeO3 nanoparticles and core-shell structured BiFeO3@SiO2 nanoparticles were synthesized by solid state reaction method, sol-gel and Stöber process (SiO2 shell) respectively. Transmission electron microscopy image confirmed the core-shell structure of BiFeO3@SiO2 nanoparticles with BiFeO3 core ˜50-90 nm and SiO2 shell ˜16 nm. X-ray diffraction and FTIR spectroscopy results showed the presence of distorted rhombohedral structure with R3c space group in all three samples. The magnetic measurement indicated the existence of room-temperature weak ferromagnetism in core-shell BiFeO3@SiO2 nanoparticles and BiFeO3 nanoparticles, whereas bulk BiFeO3 showed antiferromagnteic nature. Electron Spin Resonance results confirmed the enhancement in magnetic properties of coreshell structured BiFeO3@SiO2 nanoparticles in comparison with BiFeO3 nanoparticles and bulk BiFeO3.

  6. Protein encapsulated core-shell structured particles prepared by coaxial electrospraying: investigation on material and processing variables.

    Science.gov (United States)

    Zamani, Maedeh; Prabhakaran, Molamma P; Thian, Eng San; Ramakrishna, Seeram

    2014-10-01

    Biodegradable polymeric particles have been extensively investigated for controlled drug delivery of various therapeutic agents. 'Coaxial' electrospraying was successfully employed in this study, to fabricate core-shell PLGA particles containing bovine serum albumin (BSA) as the model protein, and the results were also compared to particles prepared by 'emulsion' electrospraying. Two different molecular weights of PLGA were employed to encapsulate the protein. Solution properties and processing parameters were found to influence the morphology of the core-shell particles. Depending on the type of solvent used to dissolve the polymer as well as the polymer concentration and molecular weight, the mean diameter of the particles varied between 3.0 to 5.5 μm. Fluorescence microscopic analysis of the electrosprayed particles using FITC-conjugated BSA demonstrated the core-shell structure of the developed particles. The encapsulation efficiency and release behavior of BSA was influenced by shell:core feeding ratio, protein concentration, and the electrospraying method. The encapsulation efficiency of BSA within the core-shell particles of high and low molecular weight PLGA was found 15.7% and 25.1% higher than the emulsion electrosprayed particles, respectively. Moreover, the total amount of BSA released from low molecular weight PLGA particles was significantly higher than high molecular weight PLGA particles within 43 days of release studies, with negligible effect on encapsulation efficiency. The technique of coaxial electrospraying has high potential for encapsulation of susceptible protein-based therapeutic agents such as growth factors for multiple drug delivery applications.

  7. Hydrothermal Preparation of TiO2-ZnO Nano Core-Shell Structure with Quantum Size Effect

    Science.gov (United States)

    Asl, Shahab Khameneh; Rad, M. Kianpour; Sadrnezhaad, S. K.

    2011-12-01

    Nano sized ZnO on TiO2 spherical core shells were prepared by using hydrothermal method. The particle size of initial TiO2 was around 20 nm, and the specific surface area was 50 m2/gr. Different ratios of TiO2 and ZnO applied to synthesize core shell particle. X-ray diffraction (XRD) used to phase characterization and crystalline size, scanning electron microscopy (SEM) to morphology and microstructure investigations. S. Brunauer, P. H. Emmett and E. Teller method (BET) to find specific surface area, Diffusive UV-visible-NIR spectrometry to bang gap calculations. The results indicate that powders with a shell of zinc oxide in specific range have the quantum size effect. Titanium oxide and zinc oxide have similar band gap, but TiO2 could act as a template to produced 2D structure of ZnO with modified physical properties.

  8. Carbon sphere@Co9S8 yolk-shell structure with good morphology stability for improved lithium storage performance

    Science.gov (United States)

    Tang, Xuekun; Huang, Jing; Feng, Qiming; Liu, Kun; Luo, Xianping; Li, Zishun

    2017-09-01

    The poor electronic conductivity and huge volume expansion of cobalt sulfides upon cycling would lead to their poor electrochemical performances for Lithium-ion batteries. Here, we rationally design a yolk-shell carbon sphere@Co9S8 (C@CS) composite, which demonstrates improved kinetics and excellent morphology stability during cycling. This structure can keep Co9S8 shell from collapse and aggregation. After cycling, a layer of thin solid electrolyte interphase is coated on the Co9S8 shells and prevented them from dissolving in electrolyte, which is helpful for the electrochemical performances. As a result, the C@CS electrodes exhibit good lithium storage performances, including excellent cyclic stability up to 300 cycles at 1000 and 2000 mA g-1 and high-rate property of 4000 mA g-1 with a capacity of 489 mA h g-1.

  9. The structure of TeV-bright shell-type supernova remnants

    Science.gov (United States)

    Yang, Chuyuan; Liu, Siming; Fang, Jun; Li, Hui

    2015-01-01

    Aims: Two-dimensional magnetohydrodynamic (MHD) simulations are used to model the emission properties of TeV-bright shell-type supernova remnants (SNRs) and to explore their nature. Methods: In the leptonic scenario for the TeV emission, the γ-ray emission is produced via inverse Compton scattering of background soft photons by high-energy electrons accelerated by the shocks of the SNRs. In a previous paper, we showed that since the energy densities of the cosmic microwave background radiation and that of the IR/optical background photons are much higher than that of the photons produced by the same high-energy electrons via the synchrotron process, the observed correlation between X-ray and TeV brightness of SNR RX J1713.7-3946 can be readily explained with the assumption that the energy density of relativistic electrons is proportional to that of the magnetic field. The TeV emissivity is therefore proportional to the magnetic field energy density and MHD simulations can be used to model the TeV structure of such remnants directly. Two-dimensional MHD simulations for SNRs are then performed under the assumption that the ambient interstellar medium is turbulent with the magnetic field and density fluctuations, following a Kolmogorov-like power-law spectrum. Results: (1) As expected, these simulations confirm early 1D and 2D modelings of these sources, namely the hydrodynamical evolution of the shock waves and amplification of magnetic field by Rayleigh-Taylor convective flows and by shocks propagating in a turbulent medium; (2) we reproduce rather complex morphological structure for γ-rays, for example, the bright thin rim and significant asymmetry, suggesting intrinsic variations of the source morphology not related to the structure of the progenitor and environment; and (3) the observed radial profile of several remnants are well reproduced with an ambient medium density of 0.1-1 cm-3. An even lower ambient density leads to a sharper drop of the TeV brightness

  10. Porous shell/dense core structures prepared in tungsten phosphate glass through template-free route

    Energy Technology Data Exchange (ETDEWEB)

    Nascimento Correa, Deleon; Alves, Oswaldo Luiz [Institute of Chemistry, University of Campinas - UNICAMP, Campinas, SP (Brazil); Odone Mazali, Italo, E-mail: mazali@iqm.unicamp.br [Institute of Chemistry, University of Campinas - UNICAMP, Campinas, SP (Brazil)

    2010-07-01

    The preparation of the 11.7Li{sub 2}O-39.7WO{sub 3}-10.9CaO-37.7P{sub 2}O{sub 5} glass (pgLWCP) was based on a one-step heat treatment of the 6Li{sub 2}O-18WO{sub 3}-43CaO-33P{sub 2}O{sub 5} (gLWCP) glass followed by leaching of the {beta}-Ca{sub 2}P{sub 2}O{sub 7} phase formed during the crystallization process. The porous structure was formed in the region formerly occupied by the {beta}-Ca{sub 2}P{sub 2}O{sub 7} phase. The gLWCP undergoes devitrification through surface crystallization. This process occurs after a thermal treatment in lower temperature and in a shorter period of time than that required for the complete crystallization. After acid leaching treatment, we obtained a core-/shell-like structure with a very well-defined dense glass (gLWCP)/porous glass (pgLWCP) interface. The pgLWCP exhibits reversible coloration-decoloration reactions.

  11. Chemical-mechanical stability of the hierarchical structure of shell nacre

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The hierarchical structure and mechanical property of shell nacre are experimentally investigated from the new aspects of chemical stability and chemistry-mechanics coupling. Through chemical deproteinization or demineralization methods together with characterization techniques at micro/nano scales,it is found that the nacre of abalone,haliotis discus hannai,contains a hierarchical structure stacked with irregular aragonite platelets and interplatelet organic matrix thin layers. Yet the aragonite platelet itself is a nanocomposite consisting of nanoparticles and intraplatelet organic matrix framework. The mean diameter of the nanoparticles and the distribution of framework are quite different for different platelets. Though the interplatelet and in-traplatelet organic matrix can be both decomposed by sodium hydroxide solution,the chemical stability of individual aragonite platelets is much higher than that of the microstructure stacked with them. Further,macroscopic bending test or nanoindentation experiment is performed on the micro/nanostructure of nacre after sodium hydroxide treatment. It is found that the Young’s modulus of both the stacked microstructure and nanocomposite platelet reduced. The reduction of the microstructure is more remark than that of the platelet. Therefore the chemical-mechanical stability of the nanocomposite platelet itself is much higher than that of the stacked microstructure of nacre.

  12. Draft crystal structure of the vault shell at 9-A resolution.

    Directory of Open Access Journals (Sweden)

    Daniel H Anderson

    2007-11-01

    Full Text Available Vaults are the largest known cytoplasmic ribonucleoprotein structures and may function in innate immunity. The vault shell self-assembles from 96 copies of major vault protein and encapsulates two other proteins and a small RNA. We crystallized rat liver vaults and several recombinant vaults, all among the largest non-icosahedral particles to have been crystallized. The best crystals thus far were formed from empty vaults built from a cysteine-tag construct of major vault protein (termed cpMVP vaults, diffracting to about 9-A resolution. The asymmetric unit contains a half vault of molecular mass 4.65 MDa. X-ray phasing was initiated by molecular replacement, using density from cryo-electron microscopy (cryo-EM. Phases were improved by density modification, including concentric 24- and 48-fold rotational symmetry averaging. From this, the continuous cryo-EM electron density separated into domain-like blocks. A draft atomic model of cpMVP was fit to this improved density from 15 domain models. Three domains were adapted from a nuclear magnetic resonance substructure. Nine domain models originated in ab initio tertiary structure prediction. Three C-terminal domains were built by fitting poly-alanine to the electron density. Locations of loops in this model provide sites to test vault functions and to exploit vaults as nanocapsules.

  13. Structure of the Particle-Hole Amplitudes in No-core Shell Model Wave Functions

    CERN Document Server

    Hayes, A C

    2009-01-01

    We study the structure of the no-core shell model wave functions for $^6$Li and $^{12}$C by investigating the ground state and first excited state electron scattering charge form factors. In both nuclei, large particle-hole ($ph$) amplitudes in the wave functions appear with the opposite sign to that needed to reproduce the shape of the $(e,e')$ form factors, the charge radii, and the B(E2) values for the lowest two states. The difference in sign appears to arise mainly from the monopole $\\Delta\\hbar\\omega=2$ matrix elements of the kinetic and potential energy (T+V) that transform under the harmonic oscillator SU(3) symmetries as $(\\lambda,\\mu)=(2,0)$. These are difficult to determine self-consistently, but they have a strong effect on the structure of the low-lying states and on the giant monopole and quadrupole resonances. The Lee-Suzuki transformation, used to account for the restricted nature of the space in terms of an effective interaction, introduces large higher-order $\\Delta\\hbar\\omega=n, n>$2, $ph$ ...

  14. Draft crystal structure of the vault shell at 9-A resolution.

    Science.gov (United States)

    Anderson, Daniel H; Kickhoefer, Valerie A; Sievers, Stuart A; Rome, Leonard H; Eisenberg, David

    2007-11-01

    Vaults are the largest known cytoplasmic ribonucleoprotein structures and may function in innate immunity. The vault shell self-assembles from 96 copies of major vault protein and encapsulates two other proteins and a small RNA. We crystallized rat liver vaults and several recombinant vaults, all among the largest non-icosahedral particles to have been crystallized. The best crystals thus far were formed from empty vaults built from a cysteine-tag construct of major vault protein (termed cpMVP vaults), diffracting to about 9-A resolution. The asymmetric unit contains a half vault of molecular mass 4.65 MDa. X-ray phasing was initiated by molecular replacement, using density from cryo-electron microscopy (cryo-EM). Phases were improved by density modification, including concentric 24- and 48-fold rotational symmetry averaging. From this, the continuous cryo-EM electron density separated into domain-like blocks. A draft atomic model of cpMVP was fit to this improved density from 15 domain models. Three domains were adapted from a nuclear magnetic resonance substructure. Nine domain models originated in ab initio tertiary structure prediction. Three C-terminal domains were built by fitting poly-alanine to the electron density. Locations of loops in this model provide sites to test vault functions and to exploit vaults as nanocapsules.

  15. Advanced Deployable Shell-Based Composite Booms for Small Satellite Structural Applications Including Solar Sails

    Science.gov (United States)

    Fernandez, Juan M.

    2017-01-01

    State of the art deployable structures are mainly being designed for medium to large size satellites. The lack of reliable deployable structural systems for low cost, small volume, rideshare-class spacecraft severely constrains the potential for using small satellite platforms for affordable deep space science and exploration precursor missions that could be realized with solar sails. There is thus a need for reliable, lightweight, high packaging efficiency deployable booms that can serve as the supporting structure for a wide range of small satellite systems including solar sails for propulsion. The National Air and Space Administration (NASA) is currently investing in the development of a new class of advanced deployable shell-based composite booms to support future deep space small satellite missions using solar sails. The concepts are being designed to: meet the unique requirements of small satellites, maximize ground testability, permit the use of low-cost manufacturing processes that will benefit scalability, be scalable for use as elements of hierarchical structures (e.g. trusses), allow long duration storage, have high deployment reliability, and have controlled deployment behavior and predictable deployed dynamics. This paper will present the various rollable boom concepts that are being developed for 5-20 m class size deployable structures that include solar sails with the so-called High Strain Composites (HSC) materials. The deployable composite booms to be presented are being developed to expand the portfolio of available rollable booms for small satellites and maximize their length for a given packaged volume. Given that solar sails are a great example of volume and mass optimization, the booms were designed to comply with nominal solar sail system requirements for 6U CubeSats, which are a good compromise between those of smaller form factors (1U, 2U and 3U CubeSats) and larger ones (12 U and 27 U future CubeSats, and ESPA-class microsatellites). Solar

  16. 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.

  17. Facile synthesis of hairy core-shell structured magnetic polymer submicrospheres and their adsorption of bovine serum albumin.

    Science.gov (United States)

    Yan, Xianming; Kong, Juan; Yang, Chongchong; Fu, Guoqi

    2015-05-01

    Highly magnetic polymer submicrospheres with a hairy core-shell structure were facilely synthesized by combining distillation-precipitation polymerization (DPP) with subsequent surface-initiated atom transfer radical polymerization (SI-ATRP), and then investigated for protein adsorption. A robust polymer shell consisting of poly(divinylbenzene-co-chloromethylstyrene) (P(DVB-co-CMS)) was coated on superparamagnetic submicrometer-sized magnetite colloid nanocrystal clusters (MCNCs) via DPP. With the benzyl chloride groups on the shell as initiator, poly(2-(dimethylamino) ethyl methacrylate) (PDMAEMA) hairs were grafted by SI-ATRP approach. The resulting hairy core-shell structured Fe3O4@ P(DVB-co-CMS)-PDMAEMA microspheres showed pH- and temperature-sensitivity, and high-magnetization. The composite microspheres were further investigated for adsorption of a typical acidic protein, i.e. bovine serum albumin (BSA). They exhibited a high binding capacity up to over 660 mg/g (corresponding to 158 DMAEMA monomer units cooperating for binding one BSA molecule) and could rapidly reach binding equilibrium within 5 min. Moreover, the adsorption of BSA was found to be remarkably dependent on the pH and salt concentration of the protein solutions, and the bound protein could be quantitatively desorbed by washing with a medium with lowered pH or raised salt concentration.

  18. Synthesis and Structure Control of A New Kind of Inelastomer Impact Modifier with Core-shell Structure and Impact Modification to PVC/CPE

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A new kind of inelastomer impact modifier with a core-shell structure was synthesized by employing a multi-step composite emulsion polymerization technique, the size and morphology structure of the core-shell particles could be controlled by the multi-step composite emulsion polymerization technique. The study of the impact strength and the elongation at break of the PVC/CPE blend with different contents of core-shell particles(C-S) indicated that the mechanical properties of PVC/CPE/C-S composite were the best when the concentration of the particle was 2.5%(mass fraction) which showed the different regularities and characteristics of elastomer toughening plastic.

  19. 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.

  20. Structure-Related Optical Fingerprints in the Absorption Spectra of Colloidal Quantum Dots: Random Alloy vs. Core/Shell Systems

    CERN Document Server

    Mourad, Daniel

    2016-01-01

    We argue that the experimentally easily accessible optical absorption spectrum can often be used to distinguish between a random alloy phase and a stoichiometrically equivalent core/shell realization of ensembles of monodisperse colloidal semiconductor quantum dots without the need for more advanced structural characterization tools. Our proof-of-concept is performed by conceptually straightforward exact-disorder tight-binding calculations. The underlying stochastical tight-binding scheme only parametrizes bulk band structure properties and does not employ additional free parameters to calculate the optical absorption spectrum, which is an easily accessible experimental property. The method is applied to selected realizations of type-I Cd(Se,S) and type-II (Zn,Cd)(Se,S) alloyed quantum dots with an underlying zincblende crystal structure and the corresponding core/shell counterparts.

  1. Photochemical synthesis of bimetallic Au-Ag nanoparticles with "core-shell" type structure by seed mediated catalytic growth

    Institute of Scientific and Technical Information of China (English)

    DONG Shou-an; TANG Chun

    2005-01-01

    The colloidal Au core/Ag shell structure composite nanoparticles were synthesized in PEG-acetone solution by photochemical route. The monodispersed Au nanoparticles with average diameter of 3.9 nm were used as growth seeds. The optical property of colloids and the sizes of composite nanoparticles were characterized when the molar ratio of Au to Ag ranges from 4 : 1 to 1 : 4. The results show that a composite nanoparticle structure similar to strawberry shape is formed at the molar ratio of Au to Ag from 4 : 1 to 1 : 1; the composite nanoparticles consisting of a core of Au and shell of Ag were generated at the 1: 4 molar ratio, having a striking feature of forming interconnected network structure.

  2. 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.

  3. Population genetic structure of the ark shell Scapharca broughtonii Schrenck from Korea, China, and Russia based on COI gene sequences.

    Science.gov (United States)

    Cho, Eun-Seob; Jung, Choon-Goon; Sohn, Sang-Gyu; Kim, Chul-Won; Han, Seock-Jung

    2007-01-01

    Haplotype distribution, gene flow, and population genetic structure of the ark shell (Scapharca broughtonii) were studied using a partial sequence of a mitochondrial COI gene. The sequence analysis of 100 specimens obtained from a total of seven localities-five in Korea, one in China, and one in Russia- revealed 29 haplotypes, ranging in sequence divergence from 0.1% to 2.1%. Among these, the most frequent haplotype, SB16, was extensively distributed over study areas, especially in all Korean localities. This extensive distribution consequently resulted in the near absence of statistically significant genetic distance. Also, a high rate of gene flow was characteristic among localities in Korea. A test of genetic population structure showed that the ark shell in Korea formed a large genetic group. Moreover, an AMOVA test to determine the allocation of the genetic variance showed that most of the variance was distributed between localities, instead of within localities. However, a significant population differentiation was found between geographic populations [i.e., Jinhae (locality 6) in Korea and Sangdong (locality 5) in China and Vladivostok (locality 7) in Russia] based on geographic distance and population structure. These distinct groups may be associated with geographic characteristics and barriers. The results suggest that most of the ark shell populations in Korea caused considerable distribution to form a genetically homogeneous and intermixing structure, whereas some of the Korean and Chinese and Russian populations had a significantly different genetic structure.

  4. Self-catalyzed MBE grown GaAs/GaAs(x)Sb(1-x) core-shell nanowires in ZB and WZ crystal structures.

    Science.gov (United States)

    Ghalamestani, Sepideh Gorji; Munshi, A Mazid; Dheeraj, Dasa L; Fimland, Bjørn-Ove; Weman, Helge; Dick, Kimberly A

    2013-10-11

    We have investigated the growth of self-catalyzed GaAs/GaAs(x)Sb(1-x) core-shell nanowires directly on Si(111) substrates by molecular beam epitaxy. The compositions of the GaAs(x)Sb(1-x) shells are tuned in a wide range where the Sb-content is varied from 10 to ~70%, covering the miscibility gap. In addition, the GaAs(x)Sb(1-x) shells are grown on both zinc blende (ZB) and wurtzite (WZ) crystal structures. Morphological and structural characterizations of the grown nanowires indicate successful transfer of the GaAs core crystal structure to the GaAs(x)Sb(1-x) shells for both ZB and WZ nanowires, with slower shell growth rate on the WZ segments.

  5. A novel approach to the systematization of α-decaying nuclei, based on shell structures

    Energy Technology Data Exchange (ETDEWEB)

    Yarman, Tolga; Azmi Altintas, Ali [Okan University, Istanbul (Turkey); Zaim, Nimet [Trakya University, Edirne (Turkey); Amon Susam, Lidya [Istanbul University, Istanbul (Turkey); Kholmetskii, Alexander [Belarus State University, Minsk (Belarus); Arik, Metin [Bogazici University, Istanbul (Turkey); Ozaydin, Fatih [Isik University, Istanbul (Turkey)

    2016-05-15

    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.)

  6. Mechanical Analysis of a Pneumatically Actuated Concentric Double-Shell Structure for Cell Stretching

    Directory of Open Access Journals (Sweden)

    Feihu Zhao

    2014-10-01

    Full Text Available An available novel system for studying the cellular mechanobiology applies an equiaxial strain field to cells cultured on a PolyDiMethylSiloxane (PDMS substrate membrane, which is stretched over the deformation of a cylindrical shell. In its application of in vitro cell culture, the in-plane strain of the substrate membrane provides mechanical stimulation to cells, and out-of-plane displacement plays an important role in monitoring the cells by a microscope. However, no analysis of the parameters has been reported yet. Therefore, in this paper, we employ analytical and computational models to investigate the mechanical behavior of the device, in terms of in-plane strain and out-of-plane displacement of the substrate membrane. As a result, mathematical descriptions are given, which are not only for quantitatively determining the applied load, but also provide the theoretical basis for the researchers to carry out structural modification, according to their needs in specific cell culture experiments. Furthermore, by computational study, the elastic modulus of PDMS is determined to allow the mechanical behavior analysis of a fabricated device. Finally, compared to the experimental results of characterizing a fabricated device, good agreement is obtained between the predicted and experimental results.

  7. The structure of TeV-bright shell-type supernova remnants

    CERN Document Server

    Yang, Chuyuan; Fang, Jun; Li, Hui

    2014-01-01

    Aims. Two-dimensional MHD simulations are used to model the emission properties of TeV-bright shell-type supernova remnants (SNRs) and to explore their nature. Methods. In the leptonic scenario for the TeV emission, the $\\gamma$-ray emission is produced via Inverse Compton scattering of background soft photons by high-energy electrons accelerated by the shocks of the SNRs. The TeV emissivity is proportional to the magnetic field energy density and MHD simulations can be used to model the TeV structure of such remnants directly. 2D MHD simulations for SNRs are then performed under the assumption that the ambient interstellar medium is turbulent with the magnetic field and density fluctuations following a Kolmogorov-like power-law spectrum. Results. (1) As expected, these simulations confirm early 1D and 2D modelings of these sources, namely the hydrodynamical evolution of the shock waves and amplification of magnetic field by Rayleigh-Taylor convective flows and by shocks propagating in a turbulent medium; (2)...

  8. Shell evolution approaching the N=20 island of inversion: structure of 26Na

    CERN Document Server

    Wilson, G L; Orr, N A; Diget, C Aa; Matta, A; Hackman, G; Williams, S J; Celik, I C; Achouri, N L; Falou, H Al; Ashley, R; Austin, R A E; Ball, G C; Blackmon, J C; Boston, A J; Boston, H C; Brown, S M; Cross, D S; Djongolov, M; Drake, T E; Hager, U; Fox, S P; Fulton, B R; Galinski, N; Garnsworthy, A B; Jamieson, D; Kanungo, R; Leach, K; Orce, J N; Pearson, C J; Porter-Peden, M; Sarazin, F; Simpson, E C; Sjue, S; Smalley, D; Sumithrarachchi, C; Triambak, S; Unsworth, C; Wadsworth, R

    2015-01-01

    The levels in 26Na with single particle character have been observed for the first time using the d(25Na,p gamma) reaction at 5 MeV/nucleon. The measured excitation energies and the deduced spectroscopic factors are in good overall agreement with (0+1) hbar-omega shell model calculations performed in a complete spsdfp basis and incorporating a reduction in the N=20 gap. Notably, the 1p3/2 neutron configuration was found to play an enhanced role in the structure of the low-lying negative parity states in 26Na, compared to the isotone 28Al. Thus, the lowering of the 1p3/2 orbital relative to the 0f7/2 occuring in the neighbouring Z=10 and 12 nuclei -- 25,27Ne and 27,29Mg -- is seen to extend to Z=11. Together with the newly measured splitting of the spin multiplets formed by odd-odd proton-neutron coupling, this provides further, stronger constraints on the modelling of the transition into the island of inversion.

  9. Spatial and Orientational Structure of the Hydration Shell of Benzene in Sub- and Supercritical Water.

    Science.gov (United States)

    Choudhary, Ashu; Chandra, Amalendu

    2015-07-09

    The spatial and orientational structure of the solvation shell of benzene in sub- and supercritical water are investigated by means of molecular dynamics simulations. The present study reveals different local organization of water molecules at different parts of the solute. The π-hydrogen-bonding between benzene and water along the axial direction is found to exist even at supercritical conditions although to a reduced extent. The coordination number of benzene decreases substantially on increase of temperature and decrease of density. While the π-hydrogen-bonded part in the axial region shows a slight expansion, the hydrophobically solvated part in the equatorial plane shows an opposite behavior as the temperature is increased from normal to the supercritical temperature. Two other distribution functions, namely the radial/angular and spatial orientational functions (SOFs) are calculated to explore the spatially resolved angular preferences of water molecules around the benzene solute. Water molecules located axial to the benzene are found to have strong inward orientation toward the solute, however an opposite behavior is found in the equatorial region. Although at supercritical conditions, the orientational distributions of water molecules are broadened, the preferential orientations in the axial and equatorial regions remain similar to that under ambient condition on average.

  10. 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.

  11. Shell quenching in Ni78: A hint from the structure of neutron-rich copper isotopes

    Science.gov (United States)

    Sieja, K.; Nowacki, F.

    2010-06-01

    Recent progress in experimental techniques allows us to study very exotic systems like neutron-rich nuclei in the vicinity of Ni78. The spectroscopy of this region can nowadays be studied theoretically in the large scale shell model calculations. In this work, we perform a shell model study of odd copper nuclei with N=40-50, in a large valence space with the Ca48 core, using a realistic interaction derived from the CD-Bonn potential. We present the crucial importance of the proton core excitations for the description of spectra and magnetic moments, which are for the first time correctly reproduced in theoretical calculations. Shell evolution from Ni68 to Ni78 is discussed in detail. A weakening of the Z=28 gap when approaching the N=50 shell closure, suggested by the experimental evidence, is confirmed in the calculations.

  12. Effects of finite element formulation on optimal plate and shell structural topologies

    CSIR Research Space (South Africa)

    Long, CS

    2009-09-01

    Full Text Available The effects of selected membrane, plate and flat shell finite element formulations on optimal topologies are numerically investigated. Two different membrane components are considered. The first is a standard 4-node bilinear quadrilateral...

  13. Density dependence of the entropy and the solvation shell structure in supercritical water via molecular dynamics simulation.

    Science.gov (United States)

    Ma, Haibo

    2012-06-07

    We perform molecular dynamics simulations of supercritical water (SCW) with a wide range of densities along a near critical isotherm using the simple point charge extended (SPC/E) pair potential in order to study the entropy and the solvation shell structure around a central water molecule. It is shown that both the translational and orientational two-particle correlation entropy terms can serve as the metrics of the translational-orientational structural orders in water and it is revealed that the translational structural order is very sensitive to the density variation in the gas-like and liquid-like region, while the orientational structural order is much more dependent upon compression in the medium-density SCW region. The comparison of the magnitudes of the full thermodynamic excess entropy and two-particle correlation entropy confirms the recent findings that the many-body terms other than two-body ones also present significant and non-neglectable contributions to the full excess entropy for the highly anomalous fluids like water. The analysis of entropy terms as a function of intermolecular distance and the orientational distribution functions as well as the three-dimensional spatial distribution functions indicate that the structural order occurs only in a much more diffused first solvation shell due to the elongated hydrogen bonds under supercritical conditions. It is revealed that no obvious second or higher neighbor shells occur in SCW, in contrast with the feature of normal liquid water that the anomalous decrease of translational order upon compression occurs mainly in the second shell.

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

    OpenAIRE

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

    2014-01-01

    The moment of inertia for nuclear collective rotations was derived within the 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 formul...

  15. Atomic structure and thermal stability of Pt-Fe bimetallic nanoparticles: from alloy to core/shell architectures.

    Science.gov (United States)

    Huang, Rao; Wen, Yu-Hua; Shao, Gui-Fang; Sun, Shi-Gang

    2016-06-22

    Bimetallic nanoparticles comprising noble metal and non-noble metal have attracted intense interest over the past few decades due to their low cost and significantly enhanced catalytic performances. In this article, we have explored the atomic structure and thermal stability of Pt-Fe alloy and core-shell nanoparticles by molecular dynamics simulations. In Fe-core/Pt-shell nanoparticles, Fe with three different structures, i.e., body-centered cubic (bcc), face-centered cubic (fcc), and amorphous phases, has been considered. Our results show that Pt-Fe alloy is the most stable configuration among the four types of bimetallic nanoparticles. It has been discovered that the amorphous Fe cannot stably exist in the core and preferentially transforms into the fcc phase. The phase transition from bcc to hexagonal close packed (hcp) has also been observed in bcc-Fe-core/Pt-shell nanoparticles. In contrast, Fe with the fcc structure is the most preferred as the core component. These findings are helpful for understanding the structure-property relationships of Pt-Fe bimetallic nanoparticles, and are also of significance to the synthesis and application of noble metal based nanoparticle catalysts.

  16. On the impact of radiation pressure on the dynamics and inner structure of dusty wind-driven shells

    Energy Technology Data Exchange (ETDEWEB)

    Martínez-González, Sergio; Silich, Sergiy; Tenorio-Tagle, Guillermo, E-mail: silich@inaoep.mx [Instituto Nacional de Astrofísica Óptica y Electrónica, AP 51, 72000 Puebla (Mexico)

    2014-04-20

    Massive young stellar clusters are strong sources of radiation and mechanical energy. Their powerful winds and radiation pressure sweep up interstellar gas into thin expanding shells that trap the ionizing radiation produced by the central clusters affecting the dynamics and the distribution of their ionized gas. Here we continue our comparison of the star cluster winds and radiation pressure effects on the dynamics of shells around young massive clusters. We calculate the impact that radiation pressure has on the distribution of matter and thermal pressure within such shells, as well as on the density-weighted ionization parameter U{sub w} , and put our results on the diagnostic diagram, which allows one to discriminate between the wind-dominated and radiation-dominated regimes. We found that model-predicted values of the ionization parameter agree well with typical values found in local starburst galaxies. Radiation pressure may affect the inner structure and the dynamics of wind-driven shells, but only during the earliest stages of evolution (before ∼3 Myr) or if a major fraction of the star cluster mechanical luminosity is dissipated or radiated away within the star cluster volume and thus the star cluster mechanical energy output is significantly smaller than star cluster synthetic models predict. However, even in these cases radiation dominates over the wind dynamical pressure only if the exciting cluster is embedded into a high-density ambient medium.

  17. Solvent-surface interactions control the phase structure in laser-generated iron-gold core-shell nanoparticles

    Science.gov (United States)

    Wagener, Philipp; Jakobi, Jurij; Rehbock, Christoph; Chakravadhanula, Venkata Sai Kiran; Thede, Claas; Wiedwald, Ulf; Bartsch, Mathias; Kienle, Lorenz; Barcikowski, Stephan

    2016-03-01

    This work highlights a strategy for the one-step synthesis of FeAu nanoparticles by the pulsed laser ablation of alloy targets in the presence of different solvents. This method allows particle generation without the use of additional chemicals; hence, solvent-metal interactions could be studied without cross effects from organic surface ligands. A detailed analysis of generated particles via transmission electron microscopy in combination with EDX elemental mapping could conclusively verify that the nature of the used solvent governs the internal phase structure of the formed nanoparticles. In the presence of acetone or methyl methacrylate, a gold shell covering a non-oxidized iron core was formed, whereas in aqueous media, an Au core with an Fe3O4 shell was generated. This core-shell morphology was the predominant species found in >90% of the examined nanoparticles. These findings indicate that fundamental chemical interactions between the nanoparticle surface and the solvent significantly contribute to phase segregation and elemental distribution in FeAu nanoparticles. A consecutive analysis of resulting Fe@Au core-shell nanoparticles revealed outstanding oxidation resistance and fair magnetic and optical properties. In particular, the combination of these features with high stability magnetism and plasmonics may create new opportunities for this hybrid material in imaging applications.

  18. Study on the DFB fiber laser accelerometer with a metal-shell-packaged single-cylinder mandrel structure

    Science.gov (United States)

    Li, Haitao; Ma, Lina; Yang, Huayong; Luo, Hong

    2014-12-01

    To realize the miniature of fiber laser accelerometers, a metal-shell-packaged single-cylinder mandrel-structured distributed feedback (DFB) fiber laser accelerometer was proposed, whose key sensing component is the DFB fiber laser with a cavity length of 16mm. Simulation results show that when the weight of the mass is 400g, the radius of the thin shell cylinder is 0.5cm, we will find that the resonance frequency of the sensor is 900Hz and its sensitivity reaches 18.1pm/g. It is also shown that its sensitivity achieved 42.8dB.re.rad/g while demodulated by an unbalanced Michelson optical fiber interferometer with 1m path difference. In addition, the effects of its structure and material parameters on the acceleration sensitivity are also studied.

  19. 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.

  20. Immobilization of Thermostable Lipase QLM on Core-Shell Structured Polydopamine-Coated Fe3O4 Nanoparticles

    Directory of Open Access Journals (Sweden)

    Chenhui Wang

    2017-02-01

    Full Text Available Here, core-shell structured polydopamine-coated Fe3O4 nanoparticles were constructed to immobilize thermostable lipase QLM from Alcaligenes sp. Systematical characterization indicated that lipase QLM was successfully immobilized on the surface of nanoparticles with an enzyme loading of 21.4 ± 1.47 mg/g immobilized enzyme. Then, the immobilized enzyme was demonstrated to possess favorable catalytic activity and stability in the ester hydrolysis, using p-nitrophenyl caprylate as the substrate. Further, it was successfully employed in the kinetic resolution of (R, S-2-octanol, and satisfactory enantioselectivity and recyclability could be obtained with an enantiomeric ratio (E of 8–15 over 10 cycle reactions. Thus, core-shell structured polydopamine-coated Fe3O4 nanoparticles can be potentially used as a carrier for enzyme immobilization to improve their activity, stability, and reusability, which is beneficial for constructing efficient catalysts for industrial biocatalysis.

  1. HANFORD DOUBLE SHELL TANK (DST) THERMAL & SEISMIC PROJECT DYTRAN ANALYSIS OF SEISMICALLY INDUCED FLUID STRUCTURE INTERACTION IN A HANFORD DOUBLE SHELL PRIMARY TANK

    Energy Technology Data Exchange (ETDEWEB)

    MACKEY, T.C.

    2006-03-14

    M&D Professional Services, Inc. (M&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

  2. Determination of the structural and chemisorption characteristics of granulated active charcoal on the basis of coconut shell

    Directory of Open Access Journals (Sweden)

    Milenković Dragan D.

    2004-01-01

    Full Text Available Wastewater purification and the acquirement of drinking water from water streams that are in most cases recipients of various industrial plants, present a significant problem nowadays. The structural characteristics of granulated active charcoal (GAC obtained by the carbonization of coconut shells and activated by steam are presented in this paper. The established kinetics of suspending cyanide from aqueous solution using GAC impregnated with copper(II acetate were studied and a mathematical model estabkusged by a regression - correlation analysis.

  3. Molecular dynamics study on core-shell structure stability of aluminum encapsulated by nano-carbon materials

    Science.gov (United States)

    Yi, Qingwen; Xu, Jingcheng; Liu, Yi; Zhai, Dong; Zhou, Kai; Pan, Deng

    2017-02-01

    A ReaxFF reactive forcefield for aluminum-carbon composite system has been developed to investigate structural stability and thermal decomposition mechanism of nano-carbon materials coating aluminum particles. Research results indicated the Al@C particles were structurally stable in a broad temperature range from room temperature up to 2735 K. In particular, the broken carbon cage self-healed to reconstruct a more stable Al@C core-shell structure after Al atoms sequentially departing from carbon cage during thermal decomposition, proffering an effective protection for aluminum surface-activeness.

  4. Polystyrene-ZnO core-shell microspheres and hollow ZnO structures synthesized with the sulfonated polystyrene templates

    Science.gov (United States)

    Yang, Yang; Chu, Ying; Zhang, Yanping; Yang, Fuyong; Liu, Jinglin

    2006-02-01

    Mono-sized sulfonated polystyrene (PS) microspheres were used as templates to prepare PS-zinc oxide (ZnO) core-shell microspheres. Two different hollow ZnO structures were obtained after removing the PS cores by solvent extraction or calcinations. However, we obtained rod-like ZnO by either using unsulfonated PS microspheres as templates or without any templates. Transmission electron microscope (TEM) and scanning electron microscope (SEM) images were used to characterize the structures and morphologies of all the samples. X-ray diffraction (XRD), electron diffraction (ED) and infrared (IR) spectra were, respectively, used to study the crystal structure and composition of samples, respectively.

  5. Synergetic Effect of Yolk-Shell Structure and Uniform Mixing of SnS-MoS₂ Nanocrystals for Improved Na-Ion Storage Capabilities.

    Science.gov (United States)

    Choi, Seung Ho; Kang, Yun Chan

    2015-11-11

    Mixed metal sulfide composite microspheres with a yolk-shell structure for sodium-ion batteries are studied. Tin-molybdenum oxide yolk-shell microspheres prepared by a one-pot spray pyrolysis process transform into yolk-shell SnS-MoS2 composite microspheres. The discharge capacities of the yolk-shell and dense-structured SnS-MoS2 composite microspheres for the 100th cycle are 396 and 207 mA h g(-1), and their capacity retentions measured from the second cycle are 89 and 47%, respectively. The yolk-shell SnS-MoS2 composite microspheres with high structural stability during repeated sodium insertion and desertion processes have low charge-transfer resistance even after long-term cycling. The synergetic effect of the yolk-shell structure and uniform mixing of the SnS and MoS2 nanocrystals result in the excellent sodium-ion storage properties of the yolk-shell SnS-MoS2 composite microspheres by improving their structural stability during cycling.

  6. Anti-wear properties of the molluscan shell Scapharca subcrenata: Influence of surface morphology, structure and organic material on the elementary wear process

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Limei, E-mail: lmtian@jlu.edu.cn [Key Laboratory of Bionic Engineering (Jilin University), Ministry of Education, Changchun 130022 (China); Tian, Ximei, E-mail: txm@jlu.edu.cn [Secretariat of the International Society of Bionic Engineering, Jilin University, Changchun 130012 (China); Wang, Yinci [Key Laboratory of Bionic Engineering (Jilin University), Ministry of Education, Changchun 130022 (China); Hu, Guangliang, E-mail: guoliang_huu@163.com [School of Automobile and Traffic Engineering, Jiangsu University, Zhenjiang 212013 (China); Ren, Luquan, E-mail: lqren@jlu.edu.cn [Key Laboratory of Bionic Engineering (Jilin University), Ministry of Education, Changchun 130022 (China)

    2014-09-01

    As a typical natural biological mineralisation material, molluscan shells have excellent wear-resistance properties that result from the interactions amongst biological coupling elements such as morphology, structure and material. The in-depth study of the wear-resistance performance of shells and the contribution made by each coupling element may help to promote the development of new bionic wear-resistant devices. The objective of this study was to investigate the influence of surface morphology (rib distribution on the shell), structure (rib coupled with nodules) and material (organic matter) on the anti-wear performance of the molluscan Scapharca subcrenata shell. The effect and contribution of each of these biological coupling elements were systematically investigated using the comparative experiment method. All three were found to exert significant effects on the shell's wear-resistance ability, and their individual contributions to that ability were revealed. Organic material can be classified as the principal coupling element, rib morphology as the secondary coupling element and the combined rib-nodule structure as the general coupling element. - Highlights: • We found that the S. subcrenata shell has an anti-wear ability. • This is related to the morphology, structure and material of the shell surface. • Organic material is the principal coupling element in its anti-wear ability. • Rib morphology could be considered the secondary coupling element. • The coupled structure could be regarded as the general coupling element.

  7. Multiple shells in IRC+10216: shell properties

    Science.gov (United States)

    Mauron, N.; Huggins, P. J.

    2000-07-01

    We report on the properties of the multiple shells in the circumstellar envelope of IRC+10216, using deep optical imaging, including data from the Hubble Space Telescope. The intensity profiles confirm the presence of thin ( ~ 0farcs5 -3'' ec), limb-brightened shells in the envelope, seen in stellar and ambient Galactic light scattered by dust. The shells are spaced at irregular intervals of ~ 5'' ec-20'' ec, corresponding to time scales of 200-800 yr, although intervals as short as ~ 1'' ec (40 yr) are seen close to the star. The location of the main shells shows a good correlation with high-resolution, molecular line maps of the inner envelope, indicating that the dust and gas are well coupled. The shell/intershell density contrast is typically ~ 3, and we find that the shells form the dominant mass component of the circumstellar envelope. The shells exhibit important evolutionary effects: the thickness increases with increasing radius, with an effective dispersion velocity of 0.7 km s-1 and there is evidence for shell interactions. Despite the presence of bipolar structure close to the star, the global shell pattern favors a roughly isotropic, episodic mass loss mechanism, with a range of time scales. Based on observations made with the Canada-France-Hawaii telescope, operated by CNRS, NRCC and UH, and on dearchived observations made with the NASA/ESA Hubble Space Telescope, operated by AURA Inc., under NASA contract NAS5-26555

  8. Structure and photoluminescence properties of TeO2-core/TiO2-shell nanowires

    Science.gov (United States)

    Park, Sunghoon; An, Soyeon; Lee, Chongmu

    2013-12-01

    TeO2-core/TiO2-shell nanowires were fabricated by thermal evaporation of Te powders and MOCVD of TiO2. The as-synthesized TeO2 nanowires showed a weak broad violet band centered at approximately 430 nm. The emission peak was shifted to a bluish violet region (∼455 nm) by the encapsulation of the nanowires with a TiO2 thin film. The intensity of the major emission from the core-shell nanowires showed strong dependence on the shell layer thickness. The strongest emission was obtained for the shell layer thickness of ∼15 nm and its intensity was approximately 80 times higher than that of the violet emission from the as-synthesized TeO2 nanowires. This enhancement in emission intensity is attributed to the subwavelength optical resonant cavity formation in the shell layer. The major emission intensity was enhanced further and blue-shifted by annealing, which might be attributed to the increase in the Ti interstitial and O vacancy concentrations in the TeO2 cores during annealing.

  9. Preparation, characterization and photocatalytic activities of ZrWMoO{sub 8}/Ag composites with core-shell structure

    Energy Technology Data Exchange (ETDEWEB)

    Liu Qinqin, E-mail: liu_qin_qin@126.com [School of Materials Science and Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang, Jiangsu 212013 (China); Sun Shuai; Li Haohua; Yang Xiaofei; Shen Hao; Cheng Xiaonong; Dong Shubin [School of Materials Science and Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang, Jiangsu 212013 (China)

    2012-11-15

    ZrWMoO{sub 8} rods with negative thermal expansion and ZrWMoO{sub 8}/Ag composites with core-shell structure were first proved to exhibit photocatalytic activity under UV-irradiation. Highlights: Black-Right-Pointing-Pointer ZrWMoO{sub 8} rods with negative thermal expansion property were first studied for its photocatalytic activity. Black-Right-Pointing-Pointer ZrWMoO{sub 8}/Ag composites with core-shell structure were prepared using a simple reduction method. Black-Right-Pointing-Pointer Improved photocatalytic activity was found in the ZrWMoO{sub 8}/Ag heterostructures. Black-Right-Pointing-Pointer The ZrWMoO{sub 8}/Ag heterostructure promotes the separation of electron-hole pairs and enhances the photocatalytic activity. - Abstract: A novel photocatalytic ZrWMoO{sub 8}/Ag composite with core-shell structure was prepared. The composites were composed of ZrWMoO{sub 8} rods with negative thermal expansion (NTE) property as cores and Ag nanoparticles as shell. The resulting products were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV-visible spectrophotometer (UV-vis DRS). The results showed that ZrWMoO{sub 8} rods displayed not only negative thermal expansion but also photocatalytic efficiency toward Rhodamine B (RB) degradation under UV-irradiation. The as-prepared ZrWMoO{sub 8}/Ag composites exhibited a higher photocatalytic activity than that of pure ZrWMoO{sub 8}, thereby implying that the ZrWMoO{sub 8}/Ag interfaces promote the separation of photogenerated electron-hole pairs and enhance the photocatalytic activity.

  10. The Cenzonic tail derived structures of transtensional faults in Bohai Sea, East China

    Science.gov (United States)

    Wang, Guangzeng; Wu, Zhiping

    2017-04-01

    Two pre-exsiting giant strike-slip fault zones, Tanlu Fault Zone and Zhangpeng Fault Zone, comprise a conjugate strike-slip fualt system in Bohai Sea. They reactivated and developped into many branches under the extensional and shear stresses indued by the combined action of plate collision and deep mantle upwelling in Cenzonic. In response to the stress concentration at the tails of those branches, various kinds of tail derived structures develop. To systematically describe and distinguish above tail derived structures, we reviewed numerous high-resolution seismic sections and plandimetric maps of Bohai Sea, such as deteiled fault system diagroms, coherence slices and 3D visualization structural diagrams, and distinguished three types of tail derived structures at the tails of the transtensional branches of Tanlu Fault Zone and Zhangpeng Fault Zone, based on their geometric characteristics, namely, extensional horsetail/imbricate fan, wedge-shaped tail, and mixed tail of extensional horsetail fan and wedge-shaped tail (the tail derived structures develops in stepovers of transtensioanl branches are not discussed in this paper). Extensional horsetail fan mainly develops at fault tails with releasing single bend and the horsetail splay faults are T faults (about 45° to main strike-slip fault), while the wedge-shaped tail mainly develops at fault tails unfavorable for strike slip, they could be straight or with gentle restaining single bend and the derived faults are mainly antithetic faults (R' shears, normally above 70° to main strike-slip fault). If the fault tail developing a wedge-shaped tail has a small releasing single bend at its tip, a extensional horsetail fan would occur at the tip of the wedge-shaped tail, viz., mixed tail derived structure. All above tail derived faults show normal throws in profile and develop in extensional quadrant of the hanging wall of those branches. And with the shear of above main strike-slip faults, the angles bewteen the main

  11. Comparison of electrorheological performance between urea-coated and graphene oxide-wrapped core-shell structured amorphous TiO2 nanoparticles

    Science.gov (United States)

    Dong, Xufeng; Huo, Shuang; Qi, Min

    2016-01-01

    Polar molecules and graphene oxide (GO) have been used as the shell materials to prepare core-shell structured particles with enhanced electrorheological (ER) properties. Nevertheless, few studies compared the ER performance and stability of the suspensions with the two kinds of shell. In this study, urea and GO are used as the shell materials to prepare TiO2/urea and TiO2/GO core-shell particles-based ER fluids, respectively. Particle characterization results indicate the two kinds of core-shell structured particles present little change in size, morphology and crystal structure compared with the bare amorphous TiO2. Some polar groups are distributed on the surface of the two kinds of core-shell structured particles, which is responsible for their improved ER performance with respect to the bare TiO2 particles. The TiO2/GO particles-based ER fluid presents higher yield stress, lower leakage current density, better sedimentation stability but lower ER efficiency than the TiO2/urea particles-based sample. The larger surface area, stronger connection with the bare TiO2 particles, and larger number of polar groups of the GO-coating is the possible reason for the different properties of TiO2/GO particles-based ER fluid compared with the TiO2/urea particles-based sample.

  12. Influence of Nano Composite Resin Repairing Gingival Wedge-shaped Defects on Periodontal Tissue%纳米复合树脂修复龈下楔状缺损后对患牙牙周组织的影响观察

    Institute of Scientific and Technical Information of China (English)

    杨玉慧

    2016-01-01

    Objective:To observe the influence of nano composite resin repairing gingival wedge-shaped defects on periodontal tissue.Methods:50 cases (50 teeth)of patients with wedge-shaped defects received nano-composite resin restoration in a hospital from May 2013 to April 2014 were selected.Observed the dental plaque index,gingival sulcus bleeding index,GCF,and aspartate aminotransferase (AST)level and alkaline phosphatase (ALP)level in gingival crevicular fluid before and after treatment in six months and 1 2 months. Results:After 6 months of restoration,the GCF level and gingival sulcus fluid AST level were significantly higher than those of before the restoration (P<0.05).After 12 months of restoration,the gingival sulcus bleeding index,GCF and gingival sulcus fluid AST levels were significantly higher than those of after 6 months of restoration (P<0.05).Conclusion:The influence of nano-composite resin restoration for gingival wedge-shaped defects on gingival periodontal tissue is small,and this effect did not cause the change of perio-dontal tissue,so the long-term effect is better,which is worthy of promotion and application.%目的::观察纳米复合树脂修复龈下楔状缺损对患牙牙周组织的影响。方法:选择2013年5月~2014年4月来某院行纳米复合树脂修复的楔状缺损的患者50例,患牙50颗。观察患牙修复前、修复后6个月及12个月的菌斑指数、龈沟出血指数、龈沟液量以及龈沟液中天冬氨酸转氨酶(AST)和碱性磷酸酶水平(ALP)。结果:修复后6个月患牙的龈沟液量和龈沟液中AST的水平显著高于修复前(P<0.05)。修复后12个月患牙龈沟出血指数、龈沟液量和龈沟液中 AST的水平显著高于修复后6个月(P<0.05)。结论:纳米复合树脂修复龈下缺损时对患牙牙周组织有影响,但是很小,而且这种影响未造成牙周骨组织的变化,因此远期效果比较好,值得推广应用。

  13. The effect of “bulk-fill”flowable resin in filling deep wedge-shaped defects:A randomized controlled clini-cal evaluation%整层充填流动树脂充填深楔状缺损的随机对照临床研究

    Institute of Scientific and Technical Information of China (English)

    李智; 许永伟; 高承志

    2015-01-01

    Objective:To observe the effect of “bulk-fill”flowable resin in filling deep wedge-shaped defects.Methods:50 pa-tients with totally 85 pairs of premolars with deep wedge-shaped defects(depth >2 mm)were included.Each pair of the defects was randomly divided into the test group and the control group,the defects were treated by “bulk-fill”flowable resin with single cure tech-nique and conventional flowable resin with incremental layering technique respectively,the tooth sensitive rate 1 week after filling,the filling failure rate,the edge coloring and secondary caries rate 2 years after filling of the 2 groups were compared.Results:There was no significant difference between the 2 groups in the sensitive rate 1 week after filling,the failure rate and the edge coloring and sec-ondary caries rate 2 years after filling(P >0.05).Conclusion:The “bulk-filled”flowable resin using single cure technique can ac-quire the same clinical effect as conventional flowable resin using incremental layering technique in filling deep wedge-shaped defects.%目的:观察新型整层充填流动树脂一次固化充填深楔状缺损的2年临床效果。方法:纳入左右成对深楔状缺损(深度>2 mm)前磨牙的患者50名,共85对前磨牙,随机分为试验组和对照组,试验组使用整层充填流动树脂一次充填固化,对照组使用传统树脂分层充填固化,比较2组患牙充填后1周牙齿敏感发生率及充填后2年充填体脱落率及边缘染色/继发龋发生率。结果:2组患牙在充填后1周牙齿敏感发生率、充填后2年充填体脱落率、边缘染色/继发龋发生率差异均无显著性(P>0.05)。结论:使用整层充填流动树脂一次固化充填深楔状缺损可达到与传统树脂分层充填相媲美的临床效果。

  14. Recent progress in the study of core-shell-structured materials with metal organic frameworks (MOFs) as shell%金属有机骨架(MOFs)为壳的核壳结构材料研究进展

    Institute of Scientific and Technical Information of China (English)

    农洁静; 赵文波; 覃显业; 刘彪; 张政

    2015-01-01

    MOFs核壳结构材料是近十几年来化工材料领域的研究热点,其中MOFs可作核,亦可作壳。本文从不同的核出发综述了以 MOFs 为壳的核壳结构材料的合成方法,如外延生长法、后合成修饰法等;概述了其展现出优于核层与壳层的特性(如选择性分离、催化性、磁性等)及以 MOFs 为壳的核壳结构材料在气体吸附、催化剂、磁性分离等应用上的研究,这给MOFs复合材料的产业化带来很大的潜力;而内核主要包括单质金属及非金属类内核、氧化物类内核、MOFs类内核;最后对MOFs为壳的核壳结构复合材料合成方法的改进和拓展、结构均一稳定、多功能化的发展作了展望。%Core-shell-structure MOFs materials became a hot spot in the field of chemical and materials over the last decade,and MOFs can act as core or shell. This paper mainly reviews the synthesis methods of core-shell-structure material with MOFs as shell according to different nuclear types,such as epitaxial growth method,and post-synthetic modifications;and summarizes the performances which are better than single core or shell,such as separation selectivity,catalysis,magnetic performance, and the development of the core-shell-structure materials with MOFs as shell in gas adsorption, catalysts,magnetic separation,which bring a large potential for MOFs composite industrialization. The cores include metallic and non-metallic element core , oxides core , and MOFs core. And the core-shell-structure composites with MOFs as shell are prospected for the improvement and development of synthesis methods in order to obtain uniform and stable structure and multi-function.

  15. Structural and optical tunability of metallodielectric composites with gradual shell growth

    Indian Academy of Sciences (India)

    Ankita Sharma; Naresh Dhiman; B P Singh; Arvind K Gathania

    2016-01-01

    Metallodielectric (gold@silica) composites were prepared by seed and grow method. The dielectric microspheres (core material) of an average size of 400 nm were synthesized by sol–gel method and gold nanoparticles (AuNPs) were prepared by reducing the chloroauric solution. Shell growth around silica (SiO2) microspheres was carried out in a multistep layer-by-layer process. The synthesized composites were characterized using techniques such as field emissionscanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and UV–Visible (UV–Vis) spectroscopy. FE-SEM and FTIR analyses have confirmed the functionalization of SiO2 surfaces with the amine terminal group along with the gold shell growth. XRD analysis has given an average crystallite size of 12.3 nm for metallodielectric composites. Absorption spectra have demonstrated the dependence of surface plasmon resonance (SPR) peak on the successive shell growth by exhibiting a red shift.

  16. An efficient hybrid / mixed element for geometrically nonlinear analysis of plate and shell structures

    Science.gov (United States)

    Duan, M.

    2004-12-01

    In this paper, a geometrically nonlinear hybrid/mixed curved quadrilateral shell element (HMSHEL4N) with four nodes is developed based on the modified Hellinger/Reissner variational principles. The performance of element is investigated and tested using some benchmark problems. A number of numerical examples of plate and shell nonlinear deflection problems are included. The results are compared with theoretical solutions and other numerical results. It is shown that HMSHEL4N does not possess spurious zero energy modes and any locking phenomenon, and is convergent and insensitive to the distorted mesh. A good agreement of the results with theoretical solutions, and better performance compared with displacement finite element method, are observed. It is seen that an efficient shell element based on stress and displacement field assumptions in solution and time is obtained.

  17. Thermal Stability of Platinum-Cobalt Bimetallic Nanoparticles: Chemically Disordered Alloys, Ordered Intermetallics, and Core-Shell Structures.

    Science.gov (United States)

    Huang, Rao; Shao, Gui-Fang; Zhang, Yang; Wen, Yu-Hua

    2017-04-12

    Pt-Co bimetallic nanoparticles are promising candidates for Pt-based nanocatalysts and magnetic-storage materials. By using molecular dynamics simulations, we here present a detailed examination on the thermal stabilities of Pt-Co bimetallic nanoparticles with three configurations including chemically disordered alloy, ordered intermetallics, and core-shell structures. It has been revealed that ordered intermetallic nanoparticles possess better structural and thermal stability than disordered alloyed ones for both Pt3Co and PtCo systems, and Pt3Co-Pt core-shell nanoparticles exhibit the highest melting points and the best thermal stability among Pt-Co bimetallic nanoparticles, although their meltings all initiate at the surface and evolve inward with increasing temperatures. In contrast, Co-Pt core-shell nanoparticles display the worst thermal stability compared with the aforementioned nanoparticles. Furthermore, their melting initiates in the core and extends outward surface, showing a typical two-stage melting mode. The solid-solid phase transition is discovered in Co core before its melting. This work demonstrates the importance of composition distribution to tuning the properties of binary nanoparticles.

  18. A core-shell structured nanocomposite material for detection, adsorption and removal of Hg(II) ions in water.

    Science.gov (United States)

    Li, Le; Tang, Shuangyang; Ding, Dexin; Hu, Nan; Yang, Shengyuan; He, Shuya; Wang, Yongdong; Tan, Yan; Sun, Jing

    2012-11-01

    In this paper, a core-shell structured nanocomposite material was prepared for the detection, adsorption and removal of Hg(ll) ions in aqueous solution. The core was made from Fe3O4 nanoparticles with superparamagnetic behavior and the outer shell was made from amorphous silica modified with pyrene-based sensing-probes. The material could detect and adsorb Hg(II) ions in aqueous solution due to its surface being modified with pyrene-based sensing-probes, and could easily be removed from the solution by magnetic force because of its core being made from magnetic Fe3O4 nanoparticles. This multifunctional core-shell structure was confirmed and characterized by TEM, IR spectra, TGA, XRD and N2 adsorption/desorption isotherms. Experiments were conducted on its functions of detection, adsorption and removal of Hg(II) ions in aqueous solution. The experimental results showed that this composite material had high sensitivity and unique selectivity to Hg(II), and that it could easily be removed from the solution.

  19. Pulse electrodeposition to prepare core-shell structured AuPt@Pd/C catalyst for formic acid fuel cell application

    Science.gov (United States)

    Lu, Xueyi; Luo, Fan; Song, Huiyu; Liao, Shijun; Li, Hualing

    2014-01-01

    A novel core-shell structured AuPt@Pd/C catalyst for the electrooxidation of formic acid is synthesized by a pulse electrodeposition process, and the AuPt core nanoparticles are obtained by a NaBH4 reduction method. The catalyst is characterized with X-ray powder diffraction and transmission electron microscopy, thermogravimetric analysis, cyclic voltammetry, CO stripping and X-ray photoelectron spectroscopy. The core-shell structure of the catalyst is revealed by the increase in particle size resulting from a Pd layer covering the AuPt core, and by a negative shift in the CO stripping peaks. The addition of a small amount of Pt improves the dispersion of Au and results in smaller core particles. The catalyst's activity is evaluated by cyclic voltammetry in formic acid solution. The catalyst shows excellent activity towards the anodic oxidation of formic acid, the mass activity reaches 4.4 A mg-1Pd and 0.83 A mg-1metal, which are 8.5 and 1.6 times that of commercial Pd/C. This enhanced electrocatalytic activity could be ascribed to the good dispersion of Au core particles resulting from the addition of Pt, as well as to the interaction between the Pd shell layer and the Au and Pt in the core nanoparticles.

  20. Synthesis and characterization of self-crosslinking fluorinated polyacrylate soap-free latices with core-shell structure

    Science.gov (United States)

    Xu, Wei; An, Qiufeng; Hao, Lifen; Zhang, Dan; Zhang, Min

    2013-03-01

    Novel self-crosslinking fluorinated polyacrylate soap-free latices (FMBN) with core-shell structure were synthesized by semicontinuous seeded emulsion polymerization method from dodecafluoroheptyl methacrylate (DFMA), methyl methacrylate (MMA), butyl acrylate (BA), and N-methylolamide (NMA) in the presence of a polymerizable emulsifier-ammonium allyloxtmethylate nonylphenol ethoxylates sulfate (DNS-86). Effects of the DNS-86 and DFMA amounts on stability and properties of the FMBN emulsions were studied. Besides, the latices and their film were characterized by Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (1H NMR) spectrum, scanning electron microscopy (SEM), transmission electron microscopy (TEM), laser particle size analyzer, differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), contact angle goniometer, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), respectively. FT-IR spectra and 1H NMR spectrum showed that DFMA successfully participated in soap-free emulsion polymerization and monomers formed the fluorinated acrylate copolymer. The resulted latex particles had the core-shell structure. The films formed from the FMBN latices thus had two Tg. Their thermal stability and Tg of the shell phase increased gradually with augment of DFMA amount in polymer. XPS, AFM and hydrophobicity analyses indicated the fluoroalkyl groups had the tendency to enrich at the film-air interface. This enrichment of fluorine at the film-air interface was more evident after the annealing process. Water contact angles of the FMBN film before and after the annealing process could attain 115.5° and 117.5°, individually.

  1. 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

  2. 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

    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...... is in general good and it is believed that the presented results and experimental-numerical calibration procedure can be of use in practical finite-element simulations of collision and grounding events with the use of shell elements. As discussed, the paper provides a clean framework for further development...

  3. 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.

  4. Incipient manifestation of the shell structure of atoms within the WDA model for the exchange and kinetic energy density functionals

    Science.gov (United States)

    Glossman, M. D.; Balbás, L. C.; Alonso, J. A.

    1995-07-01

    The radial electron density obtained for all the atoms of the main groups of the Periodic Table through the solution of the Euler equation associated with the nonlocal weighted density approximation (WDA) for the exchange and kinetic energy density functionals shows an incipient shell structure which is absent in other calculations using kinetic energy functionals based on the electronic density. The WDA radial density reveals two local maxima and the position of the first maximum correlates with the position of the maximum for the 1s orbital in the Hartree-Fock approximation. The cusp condition at the nucleus is fulfilled accurately. Also we study the density-based electron localization function (DELF) as a complementary procedure for the visualization of shells.

  5. Theoretical study of structure and production of F19Λ as a gateway to sd-shell hypernuclei

    Science.gov (United States)

    Umeya, Atsushi; Motoba, Toshio

    2016-10-01

    Energy level structures of the typical light sd-shell hypernucleus F19Λ, together with 18F, have been studied in detail with the multi-configuration shell model. Both positive-parity and negative-parity nuclear core excitations are fully taken into account by removing the spurious center-of-mass excitation effects. Corresponding to the J-PARC proposal of the 19F (K- ,π- γ) F19Λ experiment, the production cross sections have been estimated extensively, including the angular distributions. Starting with the elementary amplitudes for the K- n → Λπ- process, the microscopic DWIA calculations at high energy kaon momenta up to 1.8 GeV / c have been carried out for the first time. The calculated wave functions are also used to estimate the electromagnetic transition probabilities for both 18F and F19Λ. The detailed γ-decay schemes are presented and discussed.

  6. A Comparative Study on the Selected Area Electron Diffraction Pattern of Fe Oxide/Au Core-shell Structured Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    Qianghua LU; Kailun YAO; Dong XI; Zuli LIU; Xiaoping LUO; Qin NING

    2007-01-01

    The selected area electron diffraction (SAED) pattern of magnetic iron oxide core/gold shell nanoparticles has been studied. For the composite particles with mean size less than 10 nm, their SAED pattern is found to be different from either the pattern of pure Fe oxide nanoparticles or that of pure Au particles. Based on the fact that the ring diameters of these composite particles fit the characteristic relation for the fcc structure, the Au atoms on surfaces of the concerned particles are supposed to pack in a way more tightly than they usually do in pure Au nanoparticles. The driving force for this is the coherency strain which enables the shell material at the heterostructured interface to adapt the lattice parameters of the core.

  7. 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

  8. The structure of the shell and polar plugs of the egg of the whipworm, Trichuris trichiura (Nematoda: Trichuridae) from the Samango monkey (Cercopithecus albogularis).

    Science.gov (United States)

    Appleton, C C; White, B J

    1989-12-01

    The structure of the shell of the egg of Trichuris trichiura was examined using light microscopy as well as scanning and transmission electron microscopy. The results confirmed its three-layered structure and provided evidence that the cores of the polar plugs, which could be seen to be extensions of the shell's middle layer, could be lost en bloc, either mechanically or chemically, and in this way probably provided an exit for the first stage larva at hatching.

  9. Influence of Different Gingival Retraction Methods before Subgingival Wedge-shaped Defect Reparation on Gingival Bleeding after Repair%龈下楔状缺损修复前不同排龈方法对修复后牙龈出血的影响

    Institute of Scientific and Technical Information of China (English)

    张秀荣

    2014-01-01

    目的:观察龈下楔状缺损修复前不同排龈方法对修复后牙龈出血的影响。方法:将165例入选患者随机为三组,A组(n=55)采用不含药排龈线排龈,B组(n=55)采用含药排龈线(每英寸含有0.4±0.2 mg肾上腺素)排龈,C组( n=55)采用排龈膏排龈,记录三组患者治疗后的牙龈出血率与疼痛感以及随访1年后的牙龈指数( GI)。结果:三组患者治疗后的牙龈出血率与疼痛感差异显著( P<0.05);随访1年,三组患者均未见修复体脱落,在临床效果(包括充填体脱落、边缘密合性、继发龋、边缘着色)方面差异不显著( P>0.05)。结论:三种方法修复龈下楔状缺损均有显著疗效,但排龈膏排龈法在控制修复后牙龈出血方面更有优势。%Objective:To observe the influence of different gingival retraction methods before subgingi-val wedge-shaped defect reparation on gingival bleeding after repair .Method:165 cases were selected and divided into 3 groups randomly .Group A ( n=55 ) received gingival retraction without including medicine , Group B(n=55)received gingival retraction with medicine ( each inch has 0.4±0.2mg phenylephrine), and group C( n=55) received gingival retraction with gingival retraction paste .The gingiva bleeding rate and pain after treatment and gingival index after following up for 1 year of three groups were recorded .Result: The difference for gingiva bleeding rate and pain among three groups was not evident (P0. 05).Conclusion:Three methods repairing subgingival wedge-shaped defect has evident efficacy , and gingi-val retraction paste has more evident effect to control gingiva bleeding after repair .

  10. Enhanced microwave absorption properties and mechanism of core/shell structured magnetic nanoparticles/carbon-based nanohybrids

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Xiaosi, E-mail: sci.xsqi@gzu.edu.cn [Physics Department, Guizhou University, Guiyang 550025 (China); Nanjing National Laboratory of Microstructures and Jiangsu Provincial Laboratory for NanoTechnology, Nanjing University, Nanjing 210093 (China); Hu, Qi; Xu, Jianle; Xie, Ren; Bai, Zhongchen; Jiang, Yang; Qin, Shuijie [Physics Department, Guizhou University, Guiyang 550025 (China); Zhong, Wei, E-mail: wzhong@nju.edu.cn [Nanjing National Laboratory of Microstructures and Jiangsu Provincial Laboratory for NanoTechnology, Nanjing University, Nanjing 210093 (China); Du, Youwei [Nanjing National Laboratory of Microstructures and Jiangsu Provincial Laboratory for NanoTechnology, Nanjing University, Nanjing 210093 (China)

    2016-09-15

    Graphical abstract: In the article, core/shell Fe{sub 3}O{sub 4}/C, Fe/helical carbon nanotubes were synthesized selectively. The results indicated that the optimum reflection loss (RL) could reach −47.1 dB at 17.39 GHz with a matching thickness of 1.39 mm. The absorption bandwidth with the RL below −20 dB was up to 11.59 GHz. Moreover, based on the obtained results, the possibly enhanced microwave absorption mechanisms were also discussed in detail. - Highlights: • An efficient scheme was designed to synthesize core/shell magnetic nanoparticles/carbon-based hybrids. • By controlling the temperature, different categories of core/shell nanohybrids were synthesized. • The obtained Fe/CNT hybrid exhibits enhanced microwave absorption property. • Enhanced microwave absorbing mechanism was discussed in detail. - Abstract: An efficient scheme was designed to selectively synthesize different categories of core/shell structured magnetic nanoparticles/carbon-based nanohybrids such as Fe{sub 3}O{sub 4}/C and Fe/helical carbon nanotubes (HCNTs) through the decomposition of acetylene directly over Fe{sub 2}O{sub 3} nanotubes by controlling the pyrolysis temperature. The measured electromagnetic parameters indicated that the Fe/HCNT nanohybrids exhibited enhanced microwave absorption properties, which may be related to their special structures. The optimum reflection loss (RL) could reach −47.1 dB at 17.39 GHz with a matching thickness of 1.39 mm. The absorption bandwidth with the RL values below −20 dB was up to 11.59 GHz. Moreover, based on the obtained results, the possible enhanced EM absorption mechanisms were also discussed in detail. The results show excellent microwave absorption materials that are lightweight, have strong absorption and a wide absorption frequency band may be realized in these nanohybrids.

  11. A First-Principles Molecular Dynamics Study of the Solvation Shell Structure, Vibrational Spectra, Polarity, and Dynamics around a Nitrate Ion in Aqueous Solution.

    Science.gov (United States)

    Yadav, Sushma; Choudhary, Ashu; Chandra, Amalendu

    2017-09-15

    A first-principles molecular dynamics study is presented for the structural, dynamical, vibrational, and dipolar properties of the solvation shell of a nitrate ion in deuterated water. A detailed description of the anisotropic structure of the solvation shell is presented through calculations of various structural distributions in different conical shells around the perpendicular axis of the ion. The nitrate ion-water dimer potential energies are also calculated for many different orientations of water. The average vibrational stretch frequency of OD modes in the solvation shell is found to be higher than that of other OD modes in the bulk, which signifies a weakening of hydrogen bonds in the hydration shell. A splitting of the NO stretch frequencies and an associated fast spectral diffusion of the solute are also observed in the current study. The dynamics of rotation and hydrogen bond relaxation are found to be faster in the hydration shell than that in the bulk water. The residence time of water in the hydration shell is, however, found to be rather long. The nitrate ion is found to have a dipole moment of 0.9 D in water which can be attributed to its fluctuating interactions with the surrounding water.

  12. 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.

  13. Core-shell Mn3O4/birnessite-MnO2 hierachical structure with enhanced adsorption towards methylene blue

    Science.gov (United States)

    Huang, Feifan; Zhou, Bowen; Xiao, Han; Xiao, Wei

    2016-01-01

    The core-shell Mn3O4/birnessite-MnO2 (Mn3O4/MnO2) was successfully established by assembly of birnessite-type MnO2 over Mn3O4 backbones. The product was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), as well as UV-vis absorption spectra (UV-vis) to assess its adsorption of methylene blue (MB) from neutral aqueous solutions. Compared to the individual Mn3O4, the prepared Mn3O4/MnO2 shows enhanced adsorption capability towards MB. Such enhancement is due to the higher surface area and the unique nanosheet shells. The adsorption of MB on the surface of Mn3O4/MnO2 was studied in terms of pseudo-first-order and the pseudo-second-order kinetic models, and the latter was found better. The present study indicates that hierarchically structured core-shell manganese oxides are promising adsorbents for wastewater treatment.

  14. 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.

  15. 玻璃离子和流体树脂修复楔状缺损的疗效比较%Comparation of the Clinical Effects of Glass Ionomer Cement and Flowable Composite Resin on the Restoration of Dental Wedge-Shaped Defects

    Institute of Scientific and Technical Information of China (English)

    陆佳萍; 赵守亮; 徐培成

    2013-01-01

    目的:探讨玻璃离子和流体树脂用于楔状缺损的修复的临床效果.方法:选择105例中型楔状缺损患者(376颗患牙),楔状缺损深度大于1 mm且小于2 mm、仅出现牙本质过敏症状、无牙髓炎症状.将患者左右两侧同名牙采用自身对照法随机分为玻璃离子衬垫组(A组)和流体树脂衬垫组(B组),A组以玻璃离子和复合树脂充填;B组以流体树脂和复合树脂充填.采用Ryge和USPHS评价标准,比较术后1周、1个月、1年、3年的敏感发生率及充填体脱落率.结果:失访18例70牙,复查87例306牙,复查率为81.4%.A组楔状缺损充填修复后1周、1个月的术后敏感发生率分别为18.3 %(28/153)、9.2%(14/153),B组分别为35.9 %(55/153)、28.1%(43/153),差异均有统计学意义(P均<0.01);修复后1年和3年2组术后敏感发生率差异无统计学意义.A组患牙术后1年、3年充填体脱落率分别为9.8 %(15/153)、11.8 %(18/153),B组分别为2.6%(4/153)、3.3 %(5/153),差异均有统计学意义(P<0.05和0.01);修复后1周、1个月差异均无统计学意义.结论:采用玻璃离子和流体树脂作为夹层技术中的衬垫材料修复楔状缺损,对于预防术后敏感和降低充填体脱落率均有理想的疗效.但是玻璃离子作为衬垫材料在预防术后敏感方面要优于流体树脂,而流体树脂作为衬垫材料在修复体固位力方面则优于玻璃离子.%Objective:To compare the clinical effects of glass ionomer cement(GIC) and flowable composite resin(FCR) on the restoration of dental wedge-shaped defects as liners.Methods:A total of 376 teeth from 105 patients with wedge-shaped defects were studied and divided into Group A and Group B randomly with self-contrasted method.The depth of wedge-shaped defects was more than 1 mm and less than 2 mm,and the patients were with dentin hypersensitiveness and without pulpitis.Group A was restored with composite resin after applying flowable

  16. A novel strategy to fabricate multifunctional Fe3O4@C@TiO2 yolk-shell structures as magnetically recyclable photocatalysts

    Science.gov (United States)

    Chen, Lulu; Li, Lu; Wang, Tingting; Zhang, Lingyu; Xing, Shuangxi; Wang, Chungang; Su, Zhongmin

    2014-05-01

    Using poly(acrylic acid) (PAA) as a template, a novel Fe3O4@C@TiO2 yolk-shell structure derived from heat treatment on Fe2O3@PAA@TiO2 core-shell structures is constructed, where the interior void volume and shell thickness are readily tuned. In this method, the PAA shell between the original spherical α-Fe2O3 nanoparticle (NP) core and the outer TiO2 shell replaces the common SiO2 template leaving out the tedious treatment procedure of the template. After calcination, the α-Fe2O3 core was reduced to the Fe3O4 core providing the NPs with magnetic properties and the middle carbon coating around the magnetic core could avoid the occurrence of photodissolution. Moreover, the obtained Fe3O4@C@TiO2 yolk-shell nanocomposites (NCs) exhibit fine photocatalytic activity for the photodegradation of organic contaminants in waste water.Using poly(acrylic acid) (PAA) as a template, a novel Fe3O4@C@TiO2 yolk-shell structure derived from heat treatment on Fe2O3@PAA@TiO2 core-shell structures is constructed, where the interior void volume and shell thickness are readily tuned. In this method, the PAA shell between the original spherical α-Fe2O3 nanoparticle (NP) core and the outer TiO2 shell replaces the common SiO2 template leaving out the tedious treatment procedure of the template. After calcination, the α-Fe2O3 core was reduced to the Fe3O4 core providing the NPs with magnetic properties and the middle carbon coating around the magnetic core could avoid the occurrence of photodissolution. Moreover, the obtained Fe3O4@C@TiO2 yolk-shell nanocomposites (NCs) exhibit fine photocatalytic activity for the photodegradation of organic contaminants in waste water. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr00175c

  17. Synthesis and Properties of Water-soluble CdSe/ZnS Nanocrystals with the Type-Ⅰ Core/Shell Structure

    Institute of Scientific and Technical Information of China (English)

    WANG Deping; YU Meijuan; HUANG Wenhai; XIE Wangxing; WANG Lu

    2008-01-01

    The synthesis of CdSe/ZnS core/shell nanocrystals though aqueous phase using the coprecipitation method was reported. The influences of factors such as injection methods and dosages of precursors, reaction duration of water-bathing and the initial CdSe:ZnS molar ratio were discussed. In comparison to the CdSe plain core nanocrystals, the CdSe/ZnS core/shell nanocrystals show much brighter photoluminescence demonstrated by the photoluminescence spectra. The epitaxial growth of the core/shell structures was verified by TEM and XRD.

  18. Synthesis, structural characterization and dielectric properties of Nb doped BaTiO{sub 3}/SiO{sub 2} core–shell heterostructure

    Energy Technology Data Exchange (ETDEWEB)

    Cernea, M., E-mail: mcernea@infim.ro [National Institute of Materials Physics, P.O. Box MG-7, Bucharest-Magurele 077125 (Romania); Vasile, B.S. [University POLITEHNICA of Bucharest, Bucharest 060042 (Romania); Boni, A.; Iuga, A. [National Institute of Materials Physics, P.O. Box MG-7, Bucharest-Magurele 077125 (Romania)

    2014-02-25

    Highlights: • Optimal parameters for preparation by sol–gel of core–shell (BT-Nb{sub 0.005})/SiO{sub 2} are presented in this paper. • Single crystalline BT-Nb{sub 0.005}/SiO{sub 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{sub 3} doped with 0.5 mol%Nb{sub 2}O{sub 5} and then nanocoated with SiO{sub 2} (abbreviated as BT-Nb{sub 0.005}/SiO{sub 2}) was successful prepared using conventional sol–gel processing. Phase composition, particle morphology, structure, and electric properties of BT-Nb{sub 0.005} core and BT-Nb{sub 0.005}/SiO{sub 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{sub 3} was achieved. Furthermore, single crystalline BT-Nb{sub 0.005}/SiO{sub 2} core–nanoshell heterostructure with ∼34 nm shell thick was prepared, which is a novelty in ferroelectrics field. The ferroelectric quality of BT-Nb{sub 0.005} has suffered an alteration when the (BT-Nb{sub 0.005})/SiO{sub 2} core–shell heterostructure was realized. One-dimensional BT-Nb{sub 0.005}/SiO{sub 2} core–shell heterostructure exhibits an improvement of dielectric losses and a decrease of dielectric constant, compared to uncoated BT-Nb{sub 0.005}. The (BT-Nb{sub 0.005})/SiO{sub 2} core–shell material could be interesting for application in the composite capacitors.

  19. Constrained Hartree-Fock Theory and Study of Deformed Structures of Closed Shell Nuclei

    Science.gov (United States)

    Praharaj, Choudhury

    2016-03-01

    We have studied some N or Z = 50 nuclei in a microscopic model with effective interaction in a reasonably large shell model space. Excitation of particles across 50 shell closure leads to well-deformed excited prolate configurations. The potential energy surfaces of nuclei are studied using Hartree-Fock theory with quadrupole constraint to explore the various deformed configurations of N = 50 nuclei 82Ge , 84Se and 86Kr . Energy spectra are calculated from various intrinsic states using Peierls-Yoccoz angular momentum projection technique. Results of spectra and electromagnetic moments and transitions will be presented for N = 50 nuclei and for Z = 50 114Sn nucleus. Supported by Grant No SB/S2/HEP-06/2013 of DST.

  20. Structural and Optical Properties of Core-Shell TiO2/CdS Prepared by Chemical Bath Deposition

    Science.gov (United States)

    Al-Jawad, Selma M. H.

    2017-10-01

    Titanium dioxide (TiO2) nanorod arrays (NRAs) sensitized with cadmium sulfide (CdS) nanoparticles (NPs) were deposited by chemical bath deposition (CBD). TiO2 NRAs were also obtained by using the same method on glass substrates coated with fluorine-doped tin oxide (FTO). The structure of the FTO/TiO2/CdS core-shell was characterized by x-ray diffraction (XRD), atomic force microscopy, scanning electron microscopy, ultraviolet-visible (UV-Vis) absorption spectroscopy, photoluminescence, and photoelectrocatalysis of FTO/TiO2 and FTO/TiO2/CdS. The FTO/TiO2 conformed to anatase and rutile phase structures for different pH values and also with annealing. XRD patterns of the FTO/TiO2/CdS sample exhibited two peaks corresponding to hexagonal (100) and (101) for CdS. Scanning electron micrographs showed nanorod structures for the TiO2 thin films deposited at a pH value equal 0.7. Optical results showed the CdS deposited on nanorod TiO2 exhibited increased absorption ability in the visible light, indicating an increased photocatalytic activity for TiO2/CdS core-shell nanorods in the visible light. When illuminated with a UV-Vis light source, the TiO2/CdS core-shell films displayed high responses. A composite exists between the TiO2 nanostructure and CdS NPs because the film absorbs the incident light located in both the visible and UV-Vis regions. A higher response to UV-Vis light was attained with the use of TiO2 NRAs/CdS NPs films prepared by CBD. This approach offers a technique for fabricating photoelectrodes.

  1. A study of the valence shell electronic structure and photoionisation dynamics of para-dichlorobenzene and para-bromochlorobenzene

    Energy Technology Data Exchange (ETDEWEB)

    Powis, I. [School of Chemistry, University of Nottingham, Nottingham NG7 2RD (United Kingdom); Trofimov, A.B. [Laboratory of Quantum Chemistry, Irkutsk State University, 664003 Irkutsk (Russian Federation); A.E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, 664033 Irkutsk (Russian Federation); Bodzuk, I.L. [Laboratory of Quantum Chemistry, Irkutsk State University, 664003 Irkutsk (Russian Federation); Holland, D.M.P., E-mail: david.holland@stfc.ac.uk [Daresbury Laboratory, Daresbury, Warrington, Cheshire, WA4 4AD (United Kingdom); Potts, A.W. [Department of Physics, King’s College, Strand, London WC2R 2LS (United Kingdom); Karlsson, L. [Department of Physics, Uppsala University, Box 530, SE-751 21 Uppsala (Sweden)

    2013-03-29

    Highlights: ► Electronic structure and photoionisation dynamics of pDCB and pBCB have been studied. ► Dynamics affected by halogen atom Cooper minimum. ► Many-body effects influence inner valence shell ionisation. - Abstract: The valence shell electronic structure and photoionisation dynamics of para-dichlorobenzene and para-bromochlorobenzene have been investigated both experimentally and theoretically. High resolution photoelectron spectra of the outer valence orbitals have been recorded with HeI radiation and the observed structure has been interpreted using calculated ionisation energies and spectral intensities. The theoretical predictions for the single-hole ionic states due to outer valence ionisation agree satisfactorily with the experimental results. Ionisation from the inner valence orbitals is strongly influenced by many-body effects and the with a particular orbital is spread amongst numerous satellites. Some of the photoelectron bands exhibit vibrational progressions and tentative assignments have been proposed. The photoionisation dynamics of the outer valence orbitals of para-dichlorobenzene have been investigated theoretically by using the continuum multiple scattering approach to calculate photoionisation partial cross-sections and photoelectron anisotropy parameters. The results show that ionisation from some of the orbitals is affected by the Cooper minimum associated with the chlorine atom. Synchrotron radiation has been used to record angle resolved photoelectron spectra of the entire valence shell, for photon energies between threshold and ∼100 eV, and these have allowed the corresponding experimental data to be derived. A comparison between the predicted and measured anisotropy parameters confirms the influence of the Cooper minimum in those orbitals related to the chlorine lone-pairs.

  2. 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.

  3. Excitonic energy shell structure of self-assembled InGaAs/GaAs quantum dots.

    Science.gov (United States)

    Raymond, S; Studenikin, S; Sachrajda, A; Wasilewski, Z; Cheng, S J; Sheng, W; Hawrylak, P; Babinski, A; Potemski, M; Ortner, G; Bayer, M

    2004-05-07

    Performing optical spectroscopy of highly homogeneous quantum dot arrays in ultrahigh magnetic fields, an unprecedently well resolved Fock-Darwin spectrum is observed. The existence of up to four degenerate electronic shells is demonstrated where the magnetic field lifts the initial degeneracies, which reappear when levels with different angular momenta come into resonance. The resulting level shifting and crossing pattern also show evidence of many-body effects such as the mixing of configurations and exciton condensation at the resonances.

  4. Core-Shell Structure and Photoluminescence of CdS Quantum Dots

    Institute of Scientific and Technical Information of China (English)

    邹炳锁; 武振羽; 曹立; 戴建华; 张泽勃; 聂玉昕; 解思深

    2001-01-01

    A double-potential-well model is proposed to describe the core-shell thickness-dependent photoluminescence peaks and energy relaxations in semiconductor quantum dots (QDs). The surface effect plays an important role in the formation of new states-polaronic states around the surface of QDs. The polaronic states formed emit light due to the strong interaction between the core state (confined state) and the surface state with an enhanced participation of the size effect.

  5. The circumstellar structure of the Be shell star φ Persei. II. Modeling

    Science.gov (United States)

    Hummel, W.; Štefl, S.

    2001-03-01

    We model Fe Ii 5317 emission lines and phase resolved He I 6678 and 5876 emission lines of the bright B2e&sdO shell binary phi Per to find the size and shape of the excitation region inside the circumprimary disk. We find the Fe Ii 5317 emission to originate within 9 stellar radii in an axisymmetric disk around the primary. Orbital phase variations of He I 6678 are fit in terms of a disk sector with disk radius of 10 stellar radii and opening angle of =~ 120degr facing the secondary. This region can be alternatively described by an intersection of a sphere around the secondary and the circumprimary disk with a penetration depth of about 7 R_*. Similar fit values are found for He I 5876. The enigmatic orbital phase precedence of shell occurrence in the He I emission features is discussed. We favor a model in which the inner He I shell is deformed because of differential rotation in combination with a finite recombination time. Based on observations collected at the Ondřejov Observatory (of the Academy of Sciences of the Czech Republic), the German-Spanish Astronomical Center (DSAZ) -- Calar Alto (operated by the Max-Plank-Institut für Astronomie Heidelberg jointly with the Spanish National Commission for Astronomy) and Observatoire de Haute-Provence (OHP; CNRS, France).

  6. Investigation of acoustic scale effects and boundary effects for the similitude model of underwater complex shell-structure

    Institute of Scientific and Technical Information of China (English)

    WANG San-de; YANG De-sen; LIU Ning

    2007-01-01

    In this paper, the acoustic scale effects and boundary effects for the similitude model of underwater complex shell-structure are investigated. The similitude conditions and relations between the similitude model and its prototype were studied in the references This paper investigates the acoustic scale effects for the similitude model, which are influenced by loss factor, shear and rotatory inertia. At the same time, the boundary effects which are influenced by surface sound reflection are investigated in the experiment of similitude model. The results show that the acoustic scale effects may be controlled with model designing, the boundary effects can be controlled with experimental designing between the similitude model and its prototype.

  7. Reduced-temperature ordering of FePt nanoparticle assembled films by Fe30Pt70/Fe3O4 core/shell structure

    Institute of Scientific and Technical Information of China (English)

    He Shu-Li; Peng Yin; Liu Li-Li; Jiang Hong-Wei; Liu Li-Feng; Zheng Wu; Wang Ai-Ling

    2007-01-01

    In this paper, Fe3oPt70/Fe3O4 core/shell nanoparticles were synthesized by chemical routine and the layered polycthylenimine (PEI)-Fe30Pt70/Fe3O4 structure was constructed by molecule-mediated self-assembly technique. The dimension of core/shell structured nanoparticles was that of 4nm core and 2 nm shell. After annealing under a flow of forming gas (50%Ar2%%30%H2) for 1h at or above 400℃, the iron oxide shell was reduced to Fe and diffused to Pt-rich core, which leaded to the formation of L10 phase FePt at low temperature. The x-ray diffraction results and magnetic properties measurement showed that the chemical ordering temperature of Fe30Pt70/Fe3O4 core/shell nanoparticles assembly can be reduced to as low as 400℃. The sample annealed at 400℃ showed the coercivity of 4 KOe with the applied field of 1.5T. The core/shell structure was suggested to be an effective way to reduce the ordering temperature obviously.

  8. Immobilization of metalloporphyrins on CeO2@SiO2 with a core-shell structure prepared via microemulsion method for catalytic oxidation of ethylbenzene

    Institute of Scientific and Technical Information of China (English)

    沈丹华; 吉琳韬; 付玲玲; 董旭龙; 刘志刚; 刘强; 刘世明

    2015-01-01

    CeO2@SiO2 core−shell nanoparticles were prepared by microemulsion method, and metalloporphyrins were immobilized on the CeO2@SiO2 core−shell nanoparticles surface via amide bond. The supported metalloporphyrin catalysts were characterized by N2 adsorption−desorption isotherm (BET), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), ultraviolet and visible spectroscopy (UV-Vis), and Fourier transform infrared spectroscopy (FT-IR). The results show that the morphology of CeO2@SiO2 nanoparticles is core−shell microspheres with about 30 nm in diameter, and metalloporphyrins are immobilized on the CeO2@SiO2 core−shell nanoparticles via amide bond. Especially, the core−shell structure contains multi CeO2 core and thin SiO2 shell, which may benefit the synergistic effect between the CeO2 core and the porphyrin anchored on the very thin SiO2 shell. As a result, this supported metalloporphyrin catalysts present comparably high catalytic activity and stability for oxidation of ethylbenzene with molecular oxygen, namely, ethylbenzene conversion remains around 12% with identical selectivity of about 80%for acetophenone even after six-times reuse of the catalyst.

  9. Characteristics of the Aragonitic Layer in Adult Oyster Shells, Crassostrea gigas: Structural Study of Myostracum including the Adductor Muscle Scar

    Directory of Open Access Journals (Sweden)

    Seung-Woo Lee

    2011-01-01

    Full Text Available Myostracum, which is connected from the umbo to the edge of a scar, is not a single layer composed of prismatic layers, but a hierarchically complex multilayered shape composed of minerals and an organic matrix. Through the analysis of the secondary structure, the results revealed that a β-antiparallel structure was predominant in the mineral phase interface between the myostracum (aragonite and bottom folia (calcite. After the complete decalcification and deproteinization, the membrane obtained from the interface between the myostracum buried in upper folia, and the bottom folia was identified as chitin. The transitional zone in the interface between the adductor muscle scar and folia are verified. The myostracum disappeared at the edge of the scar of the posterior side. From this study, the entire structure of the myostracum from the adult oyster shell of Crassostrea gigas could be proposed.

  10. Self-Assembly of Crystalline Structures of Magnetic Core-Shell Nanoparticles for Fabrication of Nanostructured Materials.

    Science.gov (United States)

    Xue, Xiaozheng; Wang, Jianchao; Furlani, Edward P

    2015-10-14

    A theoretical study is presented of the template-assisted formation of crystalline superstructures of magnetic-dielectric core-shell particles. The templates produce highly localized gradient fields and a corresponding magnetic force that guides the assembly with nanoscale precision in particle placement. The process is studied using two distinct and complementary computational models that predict the dynamics and energy of the particles, respectively. Both mono- and polydisperse colloids are studied, and the analysis demonstrates for the first time that although the particles self-assemble into ordered crystalline superstructures, the particle formation is not unique. There is a Brownian motion-induced degeneracy in the process wherein various distinct, energetically comparable crystalline structures can form for a given template geometry. The models predict the formation of hexagonal close packed (HCP) and face centered cubic (FCC) structures as well as mixed phase structures due to in-plane stacking disorders, which is consistent with experimental observations. The polydisperse particle structures are less uniform than the monodisperse particle structures because of the irregular packing of different-sized particles. A comparison of self-assembly using soft- and hard-magnetic templates is also presented, the former being magnetized in a uniform field. This analysis shows that soft-magnetic templates enable an order-of-magnitude more rapid assembly and much higher spatial resolution in particle placement than their hard-magnetic counterparts. The self-assembly method discussed is versatile and broadly applies to arbitrary template geometries and multilayered and multifunctional mono- and polydisperse core-shell particles that have at least one magnetic component. As such, the method holds potential for the bottom-up fabrication of functional nanostructured materials for a broad range of applications. This work provides unprecedented insight into the assembly

  11. Simulation for double shell pinch

    Institute of Scientific and Technical Information of China (English)

    Wang Gang-Hua; Hu Xi-Jing; Sun Cheng-Wei

    2004-01-01

    Basic shock phenomena are presented in a composite pinch, a hybrid of the Z-pinch. The successive transfer of current within the plasma structure is demonstrated by our calculations. Properties of the shock wave are described.The current distribution between the two shells after the outer shell hitting the inner shell is also discussed.

  12. Ag-Sn Bimetallic Catalyst with a Core-Shell Structure for CO2 Reduction.

    Science.gov (United States)

    Luc, Wesley; Collins, Charles; Wang, Siwen; Xin, Hongliang; He, Kai; Kang, Yijin; Jiao, Feng

    2017-02-08

    Converting greenhouse gas carbon dioxide (CO2) to value-added chemicals is an appealing approach to tackle CO2 emission challenges. The chemical transformation of CO2 requires suitable catalysts that can lower the activation energy barrier, thus minimizing the energy penalty associated with the CO2 reduction reaction. First-row transition metals are potential candidates as catalysts for electrochemical CO2 reduction; however, their high oxygen affinity makes them easy to be oxidized, which could, in turn, strongly affect the catalytic properties of metal-based catalysts. In this work, we propose a strategy to synthesize Ag-Sn electrocatalysts with a core-shell nanostructure that contains a bimetallic core responsible for high electronic conductivity and an ultrathin partially oxidized shell for catalytic CO2 conversion. This concept was demonstrated by a series of Ag-Sn bimetallic electrocatalysts. At an optimal SnOx shell thickness of ∼1.7 nm, the catalyst exhibited a high formate Faradaic efficiency of ∼80% and a formate partial current density of ∼16 mA cm(-2) at -0.8 V vs RHE, a remarkable performance in comparison to state-of-the-art formate-selective CO2 reduction catalysts. Density-functional theory calculations showed that oxygen vacancies on the SnO (101) surface are stable at highly negative potentials and crucial for CO2 activation. In addition, the adsorption energy of CO2(-) at these oxygen-vacant sites can be used as the descriptor for catalytic performance because of its linear correlation to OCHO* and COOH*, two critical intermediates for the HCOOH and CO formation pathways, respectively. The volcano-like relationship between catalytic activity toward formate as a function of the bulk Sn concentration arises from the competing effects of favorable stabilization of OCHO* by lattice expansion and the electron conductivity loss due to the increased thickness of the SnOx layer.

  13. The effect of oxide shell thickness on the structural, electronic, and optical properties of Si-SiO2 core-shell nano-crystals: A (time dependent)density functional theory study

    Science.gov (United States)

    Nazemi, Sanaz; Pourfath, Mahdi; Soleimani, Ebrahim Asl; Kosina, Hans

    2016-04-01

    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-SiO2 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 (Sin+, 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-SiO2 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 SiO2 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.

  14. 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.

  15. Electronic fine structure calculation of metal complexes with three-open-shell s, d, and p configurations.

    Science.gov (United States)

    Ramanantoanina, Harry; Daul, Claude

    2017-08-01

    The ligand field density functional theory (LFDFT) algorithm is extended to treat the electronic structure and properties of systems with three-open-shell electron configurations, exemplified in this work by the calculation of the core and semi-core 1s, 2s, and 3s one-electron excitations in compounds containing transition metal ions. The work presents a model to non-empirically resolve the multiplet energy levels arising from the three-open-shell systems of non-equivalent ns, 3d, and 4p electrons and to calculate the oscillator strengths corresponding to the electric-dipole 3d (m)  → ns (1)3d (m) 4p (1) transitions, with n = 1, 2, 3 and m = 0, 1, 2, …, 10 involved in the s electron excitation process. Using the concept of ligand field, the Slater-Condon integrals, the spin-orbit coupling constants, and the parameters of the ligand field potential are determined from density functional theory (DFT). Therefore, a theoretical procedure using LFDFT is established illustrating the spectroscopic details at the atomic scale that can be valuable in the analysis and characterization of the electronic spectra obtained from X-ray absorption fine structure or electron energy loss spectroscopies.

  16. Morpho-kinematics of the planetary nebula NGC 3242: an analysis beyond its multiple-shell structure

    CERN Document Server

    Gómez-Muñoz, M A; Vázquez, R; Zavala, S; Guillén, P F; Ayala, S

    2015-01-01

    In this paper we present the results of optical high-resolution imaging and spectroscopy of the complex planetary nebula (PN) NGC~3242. Our study is based on the analysis of the narrowband H$\\alpha$ $\\lambda$6563\\AA , [O III] $\\lambda$5007\\AA , [N II] $\\lambda$6584\\AA , and [S II] $\\lambda$6724{\\AA} images, and high- resolution spectroscopy using spectral ranges centered on the H$\\alpha$ $\\lambda$6564\\AA , [N II] $\\lambda$6583\\AA , and [O III] $\\lambda$5007\\AA . We detected and analysed morphological components beyond the multiple shell structure of this PN, to investigate the small-scale morphological components aligned towards its major axis (such as knots and ansae, as well as the arc-like features) and its surroundings. Thus, we investigated the morpho-kinematical properties of NGC~3242, as well as their nature and formation. Our results regarding the elliptical double-shell structure and the distance to this nebula are in concordance with previous studies. Furthermore, we have used the software SHAPE to ...

  17. Cross-shell excitation in two-proton knockout: Structure of $^{52}$Ca

    CERN Document Server

    Gade, A; Bazin, D; Broda, R; Brown, B A; Campbell, C M; Carpenter, M P; Cook, J M; Deacon, A N; Dinca, D C; Fornal, B; Freeman, S J; Glasmacher, T; Hansen, P G; Kay, B P; Mantica, P F; Müller, W F; Terry, J R; Tostevin, J A; Zhu, S

    2006-01-01

    The two-proton knockout reaction $^9$Be($^{54}$Ti,$^{52}$Ca$ + \\gamma$) has been studied at 72 MeV/nucleon. Besides the strong feeding of the $^{52}$Ca ground state, the only other sizeable cross section proceeds to a 3$^-$ level at 3.9 MeV. There is no measurable direct yield to the first excited 2$^+$ state at 2.6 MeV. The results illustrate the potential of such direct reactions for exploring cross-shell proton excitations in neutron-rich nuclei and confirms the doubly-magic nature of $^{52}$Ca.

  18. 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.

  19. Compressive elastic moduli and polishing performance of non-rigid core/shell structured PS/SiO{sub 2} composite abrasives evaluated by AFM

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Ailian [College of Mechanical and Energy Engineering, Changzhou University, Changzhou, Jiangsu 213016 (China); Mu, Weibin [School of Materials Science and Engineering, Changzhou University, Changzhou, Jiangsu 213164 (China); Chen, Yang, E-mail: cy.jpu@126.com [School of Materials Science and Engineering, Changzhou University, Changzhou, Jiangsu 213164 (China)

    2014-01-30

    The core/shell structured polystyrene (PS)/SiO{sub 2} composite microspheres with different silica shell morphology were synthesized by a modified Stöber method. As confirmed by transmission electron microscopy (TEM), the rough discontinuous shell consisted of separate SiO{sub 2} nanoparticles for composite-A, while the smooth continuous one was composed of amorphous silica network for composite-B. Atomic force microscopy (AFM) was employed to probe the compressive Young's moduli (E) and chemical mechanical polishing (CMP) performances of the as-prepared PS/SiO{sub 2} composite microspheres. On the basis of the Hertzian contact mechanics, the calculated E values of the PS microspheres, composite-A and composite-B were 2.9 ± 0.4, 5.1 ± 1.2 and 6.0 ± 1.2 GPa, respectively. Compared to traditional abrasives, thermally grown silicon oxide wafers after polished by the core/shell PS/SiO{sub 2} composite abrasives obtained a lower root mean square roughness and a higher material removal rate value. In addition, there is an obvious effect of shell morphology of the composites on oxide CMP performance and structural stability during polishing process. This approach would provide a basis for understanding the actual role of organic/inorganic core/shell composite abrasives in the material removal process of CMP.

  20. A facile in situ self-assembly strategy for large-scale fabrication of CHS@MOF yolk/shell structure and its catalytic application in a flow system.

    Science.gov (United States)

    Gao, Hongyi; Luan, Yi; Chaikittikul, Kullapat; Dong, Wenjun; Li, Jie; Zhang, Xiaowei; Jia, Dandan; Yang, Mu; Wang, Ge

    2015-03-04

    A hierarchical yolk/shell copper hydroxysulfates@MOF (CHS@MOF, where MOF = metal-organic frameworks) structure was fabricated from a homogeneous yolk/shell CHS template composed of an active shell and a stabilized core via a facile self-template strategy at room temperature. The active shell of the template served as the source of metal ion and was in situ transformed into a well-defined MOF crystal shell, and the relatively stabilized core retained its own nature during the formation of the MOF shell. The strategy of in situ transformation of CHS shell to MOF shell avoided the self-nucleation of MOF in the solution and complex multistep procedures. Furthermore, a flow reaction system using CHS@MOF as self-supported stationary-phase catalyst was developed, which demonstrated excellent catalytic performance for aldehyde acetalization with ethanol, and high yields and selectivities were achieved under mild conditions.

  1. Stress-driven buckling patterns in spheroidal core/shell structures.

    Science.gov (United States)

    Yin, Jie; Cao, Zexian; Li, Chaorong; Sheinman, Izhak; Chen, Xi

    2008-12-09

    Many natural fruits and vegetables adopt an approximately spheroidal shape and are characterized by their distinct undulating topologies. We demonstrate that various global pattern features can be reproduced by anisotropic stress-driven buckles on spheroidal core/shell systems, which implies that the relevant mechanical forces might provide a template underpinning the topological conformation in some fruits and plants. Three dimensionless parameters, the ratio of effective size/thickness, the ratio of equatorial/polar radii, and the ratio of core/shell moduli, primarily govern the initiation and formation of the patterns. A distinct morphological feature occurs only when these parameters fall within certain ranges: In a prolate spheroid, reticular buckles take over longitudinal ridged patterns when one or more parameters become large. Our results demonstrate that some universal features of fruit/vegetable patterns (e.g., those observed in Korean melons, silk gourds, ribbed pumpkins, striped cavern tomatoes, and cantaloupes, etc.) may be related to the spontaneous buckling from mechanical perspectives, although the more complex biological or biochemical processes are involved at deep levels.

  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. Triaxial projected shell model description of high-spin band-structures in {sup 103,105}Rh isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Bhat, G.H. [Department of Physics, University of Kashmir, Srinagar 190 006 (India); Sheikh, J.A., E-mail: sjaphysics@gmail.com [Department of Physics, University of Kashmir, Srinagar 190 006 (India); Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996 (United States); Dar, W.A. [Department of Physics, University of Kashmir, Srinagar 190 006 (India); Jehangir, S. [Department of Physics, University of Kashmir, Srinagar 190 006 (India); Department of Physics, National Institute of Technology, Srinagar 190 006 (India); Palit, R., E-mail: palit@tifr.res.in [Department of Nuclear and Atomic Physics, Tata Institute of Fundamental Research, Colaba, Mumbai (India); Ganai, P.A. [Department of Physics, University of Kashmir, Srinagar 190 006 (India); Department of Physics, National Institute of Technology, Srinagar 190 006 (India)

    2014-11-10

    High-spin band structures in odd-proton {sup 103,105}Rh are investigated using the microscopic triaxial projected shell model approach. It is demonstrated that the observed band structures built on one- and three-quasiparticle states are reproduced reasonably well in the present work. Further, it is evident from the analysis of the projected wavefunctions that side-band in the low-spin regime is the normal γ-band built on the ground-state configuration. However, in the high-spin regime, the side band is shown to be highly mixed and ceases to be a γ-band. We provide a complete set of electromagnetic transition probabilities for the two bands and the experimental measurements are desirable to test the predictions of the present work.

  4. Axially connected nanowire core-shell p-n junctions: a composite structure for high-efficiency solar cells.

    Science.gov (United States)

    Wang, Sijia; Yan, Xin; Zhang, Xia; Li, Junshuai; Ren, Xiaomin

    2015-01-01

    A composite nanostructure for high-efficiency solar cells that axially connects nanowire core-shell p-n junctions is proposed. By axially connecting the p-n junctions in one nanowire, the solar spectrum is separated and absorbed in the top and bottom cells with respect to the wavelength. The unique structure of nanowire p-n junctions enables substantial light absorption along the nanowire and efficient radial carrier separation and collection. A coupled three-dimensional optoelectronic simulation is used to evaluate the performance of the structure. With an excellent current matching, a promising efficiency of 19.9% can be achieved at a low filling ratio of 0.283 (the density of the nanowire array), which is much higher than the tandem axial p-n junctions.

  5. Theory for the atomic shell structure of the cluster magnetic moment and magnetoresistance of a cluster ensemble

    Science.gov (United States)

    Jensen, P. J.; Bennemann, K. H.

    1995-12-01

    We present a simple theory for the cluster size dependence of the average cluster magnetic moment of transition metal clusters. Assuming a local environmental dependence of the atomic magnetic moments, the cluster magnetization exhibits a magnetic shell structure, reflecting the atomic structure of the cluster. Thus, the observed oscillations of the average cluster magnet moment may serve as a fingerprint of the cluster geometry. We also discuss the giant magnetoresistance (GMR) exhibited by an ensemble of magnetic clusters embedded in a metallic matrix. It is shown that the magnetic anisotropy affects strongly the magnetization of the cluster ensemble under certain conditions. Since the GMR depends on the cluster ensemble magnetization, it can be used to determine the cluster magnetic anisotropy energy.

  6. [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.

  7. 排龈联合流动树脂衬层技术修复楔状缺损临床疗效观察%Clinical effect of gingival retraction combined with lfowable composite resin as a liner for restoring dental wedge-shaped defects

    Institute of Scientific and Technical Information of China (English)

    张瑶; 张司晨; 万领; 曹钰

    2015-01-01

    ObjectiveTo evaluate the clinical effect of gingival retraction combined with flowable composite resin as a liner for restoring dental wedge-shaped defects.MethodsSixty-five patients with four equivalent non-carious cervical lesions on bilateral maxillary premolars were enrolled in this study. Group I was treated only with composite resin, group II was treated with gingival retraction technique and composite resin filling, group III was treated with flowable composite resin as a liner and then composite resin filling, group IV was gingival retraction combined with flowable composite resin as a liner and composite resin filling eventually. The patients were followed up for one year. The results were statistically analyzed. ResultsThere was significant difference in one year success rates between group I and group IV(P 0.05) .ConclusionEffective gingival retraction combined with flowable composite resin as a liner is a good choice for treating dental wedge-shaped defects.%目的:评估采用排龈联合流动树脂衬层技术修复楔状缺损的临床疗效。方法选择65例楔状缺损患者,每个患者的双侧上颌前磨牙均存在齐龈的4个楔状缺损(共260颗牙),将每个患者的4颗楔状缺损牙随机分为Ⅰ、Ⅱ、Ⅲ、Ⅳ4组,分别用光固化复合树脂直接充填,排龈+光固化复合树脂直接充填,光固化流动树脂衬层+复合树脂充填,排龈+光固化流动树脂衬层+复合树脂充填4种方式进行修复,于修复后1年进行观察对比。以改良的美国公共卫生署的直接临床评价系统(USPHS)评估疗效,数据进行卡方检验。结果1年复查结果显示,色泽协调性、边缘着色、边缘密合性、表面形态4个方面,4组间A、B分级间差异均无统计学意义(P>0.05)。成功率方面Ⅰ组和Ⅳ组间差异有统计学意义(P<0.05),Ⅳ组排龈+光固化流动树脂衬层+复合树脂充填临床疗效最好

  8. Aligned PVDF-TrFE nanofibers with high-density PVDF nanofibers and PVDF core–shell structures for endovascular pressure sensing.

    Science.gov (United States)

    Sharma, Tushar; Naik, Sahil; Langevine, Jewel; Gill, Brijesh; Zhang, John X J

    2015-01-01

    Nanostructures of polyvinyledenedifluoride-tetrafluoroethylene (PVDF-TrFE), a semicrystalline polymer with high piezoelectricity, results in significant enhancement of crystallinity and better device performance as sensors, actuators, and energy harvesters. Using electrospinning of PVDF to manufacture nanofibers, we demonstrate a new method to pattern high-density, highly aligned nanofibers. To further boost the charge transfer from such a bundle of nanofibers, we fabricated novel core-shell structures. Finally, we developed pressure sensors utilizing these fiber structures for endovascular applications. The sensors were tested in vitro under simulated physiological conditions. We observed significant improvements using core-shell electrospun fibers (4.5 times gain in signal intensity, 4000 μV/mmHg sensitivity) over PVDF nanofibers (280 μV/mmHg). The preliminary results showed that core-shell fiber-based devices exhibit nearly 40-fold higher sensitivity, compared to the thin-film structures demonstrated earlier.

  9. Structural variation of solid core and thickness of porous shell of 1.7 μm core-shell silica particles on chromatographic performance: narrow bore columns.

    Science.gov (United States)

    Omamogho, Jesse O; Hanrahan, John P; Tobin, Joe; Glennon, Jeremy D

    2011-04-15

    Chromatographic and mass transfer kinetic properties of three narrow bore columns (2.1×50 mm) packed with new core-shell 1.7 μm EIROSHELL™-C(18) (EiS-C(18)) particles have been studied. The particles in each column varied in the solid-core to shell particle size ratio (ρ), of 0.59, 0.71 and 0.82, with a porous silica shell thickness of 350, 250 and 150 nm respectively. Scanning and transmission electron microscopy (SEM and TEM), Coulter counter analysis, gas pycnometry, nitrogen sorption analysis and inverse size exclusion chromatography (ISEC) elucidated the physical properties of these materials. The porosity measurement of the packed HILIC and C(18) modified phases provided the means to estimate the phase ratios of the three different shell columns (EiS-150-C(18), EiS-250-C(18) and EiS-350-C(18)). The dependence of the chromatographic performance to the volume fraction of the porous shell was observed for all three columns. The naphtho[2,3-a]pyrene retention factor of k'∼10 on the three EiS-C(18s) employed to obtain the height equivalents to theoretical plates (HETPs) data were achieved by varying the mobile phase compositions and applying the Wilke and Chang relationship to obtain a parallel reduced linear velocity. The Knox fit model gave the coefficient of the reduce HETPs for the three EiS-C(18s). The reduced plate height minimum h(min)=1.9 was achieved for the EiS-150-C(18) column, and generated an efficiency of over 350,000 N/m and h(min)=2.5 equivalent to an efficiency of 200,000 N/m for the EiS-350-C(18) column. The efficiency loss of the EiS-C18 column emanating from the system extra-column volume was discussed with respect to the porous shell thickness.

  10. Structural and Optical Analysis of the Bio-mineralized Photonic Structures in the Shell of the Blue- Rayed Limpet Ansates Pellucida

    Science.gov (United States)

    Kolle, Mathias; Li, Ling; Kolle, Stefan; Weaver, James; Ortiz, Christine; Aizenberg, Joanna

    2013-03-01

    Many terrestrial biological organisms have evolved a variety of micro- and nanostructures that provide unique optical signatures including distinctive, dynamic coloration, high reflectivity or superior whiteness. Recently, photonic structures have also been found in the shells or spines of marine animals. Life under water imposes very distinct constraints on organisms relying on visual communication and on the designs and the materials involved in aquatic photonic structures. Here, we present a bio-mineralized calcium carbonate - based crystalline photonic system buried in the shell of the blue-rayed limpet Ansates pellucida. The structure consists of a layered stack of calcite lamellae with uniform thickness and inter-lamella spacing. This arrangement lies at the origin of the blue-green iridescence of the organism's characteristic stripes, which is caused by multilayer interference. The multilayer is supported by a disordered array of spherical particles with an average diameter of 300nm, likely serving to enhance the contrast of the blue stripes. We present a full structural and optical characterization of this bio-mineralised marine photonic system, supported by optical FDTD modeling. The authors gratefully acknowledge financial support by the Air Force Office of Scientific Research under Award No. FA9550-09-1-0669-DOD35CAP. M. Kolle is grateful for support from the Alexander von Humboldt - Foundation.

  11. Effects of Temperature and Pore Structure on High Surface Area-Activated Carbon Obtained from Peanut Shells.

    Science.gov (United States)

    Kalpana, D; Lee, Y S

    2016-03-01

    Activated carbon was synthesized from peanut shells by treating with H3PO4 with an intention to enhance the surface area and to find its electrochemical performance in EDLC as electrode material. The powdered peanut shells were pyrolyzed at three different temperatures namely 300 degrees C, 600 degrees C and 800 degrees C respectively. The structural and surface properties of the pyrolyzed carbon materials were studied using N2 adsorption/desorption, Raman, TEM and SEM analysis. There has been remarkable increase in the surface area of the carbon pyrolyzed at 600 degrees C due to the effect of pore generations. The surface area of the 600 degrees C pyrolyzed sample was found to be 1629 m2/g. The electrochemical properties of all the samples were evaluated by cyclic voltammetry, impedance spectroscopy, and galvanostatic charge-discharge tests. The system showed excellent cycleability and a maximum specific capacitance of 291 Fg(-1) was obtained in a 0.1 M H2SO4 electrolyte solution. The effects of the various properties of the activated carbon on the EDLC performance are discussed.

  12. Pyrolysis of hazelnut shells in a fixed-bed tubular reactor. Yields and structural analysis of bio-oil

    Energy Technology Data Exchange (ETDEWEB)

    Puetuen, A.E.; Oezcan, A.; Puetuen, E. [Department of Chemical Engineering, Faculty of Engineering and Architecture, Yunusemre Campus, Anadolu University, 26470 Eskisehir (Turkey)

    1999-09-01

    Fixed-bed pyrolysis experiments have been conducted on a sample of hazelnut shells to determine the possibility of being a potential source of renewable fuels and chemical feedstocks. The effects of pyrolysis temperature and well-sweep gas atmosphere (N{sub 2}) on the pyrolysis yields and chemical compositions have been investigated. The maximum bio-oil yield of 23.1 wt.% was obtained in N{sub 2} atmosphere at a pyrolysis temperature of 500C and heating rate of 7 K min{sup -1}. The pyrolysis products were characterised by elemental analysis and various chromatographic and spectroscopic techniques and also compared with currently utilised transport fuels by simulated distillation. Bio-oil was then fractionated into pentane soluble and insoluble compounds (asphaltenes). Pentane soluble was then solvent fractionated into pentane, toluene, ether and methanol subfractions by fractionated column chromatography. The aliphatic and low-molecular-weight aromatic subfractions of the bio-oil were then analyzed by capillary column gas-liquid chromatography and GC/MS. Further structural analysis of bio-oil and aromatic and polar subfractions FTIR and {sup 1}H-NMR spectra were obtained. The chemical characterization has shown that the bio-oil obtained from hazelnut shells was quite similar to the crude oil and shale oil

  13. 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. PMID:28102314

  14. 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

    2017-01-19

    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 Ti(3+) 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.

  15. 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.

  16. Structural characterization of Pt-Pd and Pd-Pt core-shell nanoclusters at atomic resolution.

    Science.gov (United States)

    Sanchez, Sergio I; Small, Matthew W; Zuo, Jian-min; Nuzzo, Ralph G

    2009-06-24

    We describe the results of a study at atomic resolution of the structures exhibited by polymer-capped monometallic and bimetallic Pt and Pd nanoclusters--models for nanoscale material electrocatalysts--as carried out using an aberration-corrected scanning transmission electron microscope (STEM). The coupling of sub-nanometer resolution with Z-contrast measurements provides unprecedented insights into the atomic structures and relative elemental speciation of Pt and Pd within these clusters. The work further defines the nature of deeply quenched states that prevent facile conversions of core-shell motifs to equilibrium alloys and the nature of nonidealities such as twinning (icosahedral cores) and atomic segregation that these structures can embed. The nature of the facet structure present in these model systems is revealed by theory directed modeling in which experimental intensity profiles obtained in Z-contrast measurements at atomic resolution are compared to simulated intensity profiles using theoretically predicted cluster geometries. These comparisons show close correspondences between experiment and model and highlight striking structural complexities in these systems that are compositionally sensitive and subject to amplification by subsequent cluster growth processes. The work demonstrates an empowering competency in nanomaterials research for STEM measurements carried out using aberration corrected microscopes, approaches that hold considerable promise for characterizing the structure of these and other important catalytic materials systems at the atomic scale.

  17. 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

  18. Structural vibration a uniform accurate solution for laminated beams, plates and shells with general boundary conditions

    CERN Document Server

    Jin, Guoyong; Su, Zhu

    2015-01-01

    This book develops a uniform accurate method which is capable of dealing with vibrations of laminated beams, plates and shells with arbitrary boundary conditions including classical boundaries, elastic supports and their combinations. It also provides numerous solutions for various configurations including various boundary conditions, laminated schemes, geometry and material parameters, which fill certain gaps in this area of reach and may serve as benchmark solutions for the readers. For each case, corresponding fundamental equations in the framework of classical and shear deformation theory are developed. Following the fundamental equations, numerous free vibration results are presented for various configurations including different boundary conditions, laminated sequences and geometry and material properties. The proposed method and corresponding formulations can be readily extended to static analysis.

  19. 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 Nb3Sn 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 Nb3Sn MJR conductor and segmented bronze poles. The last two models (TQS02a, b) used Nb3Sn 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.

  20. Stark effect in a wedge-shaped quantum box

    CERN Document Server

    Reyes-Esqueda, J A; Castillo-Mussot, M; Vazquez, G J; Reyes-Esqueda, Jorge-Alejandro; Mendoza, Carlos I.; Castillo-Mussot, Marcelo del; Vazquez, Gerardo J.

    2005-01-01

    The effect of an external applied electric field on the electronic ground state energy of a quantum box with a geometry defined by a wedge is studied by carrying out a variational calculation. This geometry could be used as an approximation for a tip of a cantilever of an atomic force microscope. We study theoretically the Stark effect as function of the parameters of the wedge: its diameter, angular aperture and thickness; as well as function of the intensity of the external electric field applied along the axis of the wedge in both directions; pushing the carrier towards the wider or the narrower parts. A confining electronic effect, which is sharper as the wedge dimensions are smaller, is clearly observed for the first case. Besides, the sign of the Stark shift changes when the angular aperture is changed from small angles to angles theta>pi. For the opposite field, the electronic confinement for large diameters is very small and it is also observed that the Stark shift is almost independent with respect t...

  1. Dietary Probiotics Affect Gastrointestinal Microbiota, Histological Structure and Shell Mineralization in Turtles.

    Directory of Open Access Journals (Sweden)

    Mateusz Rawski

    Full Text Available Probiotics are widely used in nutrition, and their mode of action is intensively studied in mammals and birds; however, it is almost unknown in reptiles. In the present study, Trachemys scripta scripta and Sternotherus odoratus were used to assess the effects of dietary probiotics on chelonian gastrointestinal tract microecology. In the first, 20-week experiment, 40 young T. s. scripta were randomly distributed to four experimental groups: 1st, (CON--with no additives; 2nd, (SSPA with Bacillus subtilis PB6; 3rd, (MSP--with multiple strain probiotic; and 4th, (SSPB with Bacillus subtilis C-3102. The first study has shown that SSPA and MSP decreased the numbers of total bacteria, Enterobacteriace, Staphylococcus sp. and Streptococcus sp. excreted to water and increased the villous height and mucosa thickness in duodenum. SSPB improved the duodenal microstructure; however, it also increased numbers of kanamycin and vancomycin resistant bacteria, Staphylococcus sp. and Streptococcus sp., in water. In the second, 52-week experiment, 30 S. odoratus were randomly assigned to three dietary treatments. CON, SSPA and MSP groups. The MSP preparation increased the body weight gain, crude ash, Ca and P share in the turtles' shells. Both probiotics affected duodenal histomorphology. SSPA decreased the villous height, while MSP increased the villous height and mucosa thickness, and decreased the crypt depth. SSPA decreased the concentrations of bacteria excreted to water. In the case of intestinal microbiota, bacteria suppressing effects were observed in the case of both probiotics. MSP increased the number of Bifidobacterium sp. and Lactobacillus sp./Enteroccoccus sp., and decreased the number of Clostridium perfringens and Campylobacter sp. in the small intestine. In the large intestine it lowered, amongst others, Bacteroides-Pervotella cluster, Clostridium leptum subgroup and Clostridium perfringens numbers. The above-mentioned results suggest that

  2. Dietary Probiotics Affect Gastrointestinal Microbiota, Histological Structure and Shell Mineralization in Turtles.

    Science.gov (United States)

    Rawski, Mateusz; Kierończyk, Bartosz; Długosz, Jakub; Świątkiewicz, Sylwester; Józefiak, Damian

    2016-01-01

    Probiotics are widely used in nutrition, and their mode of action is intensively studied in mammals and birds; however, it is almost unknown in reptiles. In the present study, Trachemys scripta scripta and Sternotherus odoratus were used to assess the effects of dietary probiotics on chelonian gastrointestinal tract microecology. In the first, 20-week experiment, 40 young T. s. scripta were randomly distributed to four experimental groups: 1st, (CON)--with no additives; 2nd, (SSPA) with Bacillus subtilis PB6; 3rd, (MSP)--with multiple strain probiotic; and 4th, (SSPB) with Bacillus subtilis C-3102. The first study has shown that SSPA and MSP decreased the numbers of total bacteria, Enterobacteriace, Staphylococcus sp. and Streptococcus sp. excreted to water and increased the villous height and mucosa thickness in duodenum. SSPB improved the duodenal microstructure; however, it also increased numbers of kanamycin and vancomycin resistant bacteria, Staphylococcus sp. and Streptococcus sp., in water. In the second, 52-week experiment, 30 S. odoratus were randomly assigned to three dietary treatments. CON, SSPA and MSP groups. The MSP preparation increased the body weight gain, crude ash, Ca and P share in the turtles' shells. Both probiotics affected duodenal histomorphology. SSPA decreased the villous height, while MSP increased the villous height and mucosa thickness, and decreased the crypt depth. SSPA decreased the concentrations of bacteria excreted to water. In the case of intestinal microbiota, bacteria suppressing effects were observed in the case of both probiotics. MSP increased the number of Bifidobacterium sp. and Lactobacillus sp./Enteroccoccus sp., and decreased the number of Clostridium perfringens and Campylobacter sp. in the small intestine. In the large intestine it lowered, amongst others, Bacteroides-Pervotella cluster, Clostridium leptum subgroup and Clostridium perfringens numbers. The above-mentioned results suggest that probiotics are useful in

  3. 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.

  4. Vanadium fine-structure K-shell electron impact ionization cross sections for fast-electron diagnostic in laser–solid experiments

    Energy Technology Data Exchange (ETDEWEB)

    Palmeri, P., E-mail: patrick.palmeri@umons.ac.be [Astrophysique et Spectroscopie, Université de Mons - UMONS, B-7000 Mons (Belgium); Quinet, P., E-mail: pascal.quinet@umons.ac.be [Astrophysique et Spectroscopie, Université de Mons - UMONS, B-7000 Mons (Belgium); IPNAS, Université de Liège, B-4000 Liège (Belgium); Batani, D., E-mail: batani@celia.u-bordeaux1.fr [CELIA, Université de Bordeaux, F-33400 Talence (France)

    2015-09-15

    The K-shell electron impact ionization (EII) cross section, along with the K-shell fluorescence yield, is one of the key atomic parameters for fast-electron diagnostic in laser–solid experiments through the K-shell emission cross section. In addition, in a campaign dedicated to the modeling of the K lines of astrophysical interest (Palmeri et al. (2012)), the K-shell fluorescence yields for the K-vacancy fine-structure atomic levels of all the vanadium isonuclear ions have been calculated. In this study, the K-shell EII cross sections connecting the ground and the metastable levels of the parent vanadium ions to the daughter ions K-vacancy levels considered in Palmeri et al. (2012) have been determined. The relativistic distorted-wave (DW) approximation implemented in the FAC atomic code has been used for the incident electron kinetic energies up to 20 times the K-shell threshold energies. Moreover, the resulting DW cross sections have been extrapolated at higher energies using the asymptotic behavior of the modified relativistic binary encounter Bethe model (MRBEB) of Guerra et al. (2012) with the density-effect correction proposed by Davies et al. (2013)

  5. The Corneoscleral Shell of the Eye: an Age-Related Analysis of Structural Biomechanical Properties. Literature review

    Directory of Open Access Journals (Sweden)

    E. N. Iomdina

    2016-01-01

    Full Text Available Structural biomechanical properties of the ocular corneoscleral shell largely determine its anatomic and optical parameters and its supporting and protective function. Therefore, changes related to age restructuring processes may affect the state of the cornea and the sclera, which should be taken into account in diagnosing eye diseases, especially age-related. According to actual literary data, age-related changes of the corneoscleral shell affecting its biomechanical properties involve all connective tissue components of the extracellular matrix: fibrous proteins (collagen and elastin and intermediate substance components (proteoglycans and glycosaminoglycans. Aged patients have a larger diameter of elastic fiber fibrils in the external part of the sclera and a lower density of fibrils in the center as compared to young patients, which is an evidence of elastin damage at the molecular level and fibril degeneration. Age-related changes of proteoglycans are primarilymanifested in hydration loss, which leads to an increase in corneal and sclera density and regional thinning of tissues. Agerelated changes of collagen are less expressed than those of elastin and proteoglycans. Yet, the distance between collagen fibrils in the cornea becomes smaller with age; they are subject to destruction, and small spaces devoid of collagen tend to appear in the posterior stroma. The most pronounced age-related degenerative changes of collagen in the deeper layers of the corneal stroma occur in the limb, which accumulates more cross striated collagen fibrils. Recent years of research have shown that the formation of cross-linked chemical bonds, i.e. intra- and intermolecular cross links of collagen is the most important structural factor. It is this particular process that is responsible for structural stability of the corneal and scleral tissue, which tends to change with age or due to certain eye diseases, such as keratoconus or progressive myopia

  6. 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

    2017-02-01

    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(Z0.5-T0.5)) 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.

  7. Polydopamine-coated, nitrogen-doped, hollow carbon-sulfur double-layered core-shell structure for improving lithium-sulfur batteries.

    Science.gov (United States)

    Zhou, Weidong; Xiao, Xingcheng; Cai, Mei; Yang, Li

    2014-09-10

    To better confine the sulfur/polysulfides in the electrode of lithium-sulfur (Li/S) batteries and improve the cycling stability, we developed a double-layered core-shell structure of polymer-coated carbon-sulfur. Carbon-sulfur was first prepared through the impregnation of sulfur into hollow carbon spheres under heat treatment, followed by a coating polymerization to give a double-layered core-shell structure. From the study of scanning transmission electron microscopy (STEM) images, we demonstrated that the sulfur not only successfully penetrated through the porous carbon shell but also aggregated along the inner wall of the carbon shell, which, for the first time, provided visible and convincing evidence that sulfur preferred diffusing into the hollow carbon rather than aggregating in/on the porous wall of the carbon. Taking advantage of this structure, a stable capacity of 900 mA h g(-1) at 0.2 C after 150 cycles and 630 mA h g(-1) at 0.6 C after 600 cycles could be obtained in Li/S batteries. We also demonstrated the feasibility of full cells using the sulfur electrodes to couple with the silicon film electrodes, which exhibited significantly improved cycling stability and efficiency. The remarkable electrochemical performance could be attributed to the desirable confinement of sulfur through the unique double-layered core-shell architectures.

  8. Facile synthesis of multi-shell structured binary metal oxide powders with a Ni/Co mole ratio of 1:2 for Li-Ion batteries

    Science.gov (United States)

    Choi, Seung Ho; Park, Sun Kyu; Lee, Jung-Kul; Kang, Yun Chan

    2015-06-01

    Multi-shell structured binary transition metal oxide powders with a Ni/Co mole ratio of 1:2 are prepared by a simple spray drying process. Precursor powder particles prepared by spray drying from a spray solution of citric acid and ethylene glycol have completely spherical shape, fine size, and a narrow size distribution. The precursor powders turn into multi-shell powders after a post heat-treatment at temperatures between 250 and 800 °C. The multi-shell structured powders are formed by repeated combustion and contraction processes. The multi-shell powders have mixed crystal structures of Ni1-xCo2O4-x and NiO phases regardless of the post-treatment temperature. The reversible capacities of the powders post-treated at 250, 400, 600, and 800 °C after 100 cycles are 584, 913, 808, and 481 mA h g-1, respectively. The low charge transfer resistance and high lithium ion diffusion rate of the multi-shell powders post-treated at 400 °C with optimum grain size result in superior electrochemical properties even at high current densities.

  9. 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.

  10. Structure and mechanism of the formation of core–shell nanoparticles obtained through a one-step gas-phase synthesis by electron beam evaporation

    Directory of Open Access Journals (Sweden)

    Andrey V. Nomoev

    2015-03-01

    Full Text Available The structure of core–shell Cu@silica and Ag@Si nanoparticles obtained in one-step through evaporation of elemental precursors by a high-powered electron beam are investigated. The structure of the core and shell of the particles are investigated in order to elucidate their mechanisms of formation and factors affecting the synthesis. It is proposed that the formation of Cu@silica particles is mainly driven by surface tension differences between Cu and Si while the formation of Ag@Si particles is mainly driven by differences in the vapour concentration of the two components.

  11. Structure and mechanism of the formation of core-shell nanoparticles obtained through a one-step gas-phase synthesis by electron beam evaporation.

    Science.gov (United States)

    Nomoev, Andrey V; Bardakhanov, Sergey P; Schreiber, Makoto; Bazarova, Dashima G; Romanov, Nikolai A; Baldanov, Boris B; Radnaev, Bair R; Syzrantsev, Viacheslav V

    2015-01-01

    The structure of core-shell Cu@silica and Ag@Si nanoparticles obtained in one-step through evaporation of elemental precursors by a high-powered electron beam are investigated. The structure of the core and shell of the particles are investigated in order to elucidate their mechanisms of formation and factors affecting the synthesis. It is proposed that the formation of Cu@silica particles is mainly driven by surface tension differences between Cu and Si while the formation of Ag@Si particles is mainly driven by differences in the vapour concentration of the two components.

  12. 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

  13. Recent Advances in Shell Evolution with Shell-Model Calculations

    CERN Document Server

    Utsuno, Yutaka; Tsunoda, Yusuke; Shimizu, Noritaka; Honma, Michio; Togashi, Tomoaki; Mizusaki, Takahiro

    2014-01-01

    Shell evolution in exotic nuclei is investigated with large-scale shell-model calculations. After presenting that the central and tensor forces produce distinctive ways of shell evolution, we show several recent results: (i) evolution of single-particle-like levels in antimony and cupper isotopes, (ii) shape coexistence in nickel isotopes understood in terms of configuration-dependent shell structure, and (iii) prediction of the evolution of the recently established $N=34$ magic number towards smaller proton numbers. In any case, large-scale shell-model calculations play indispensable roles in describing the interplay between single-particle character and correlation.

  14. 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

  15. 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.

  16. Tungsten Micropowder/Copper Nanoparticle Core/Shell-Structured Composite Powder Synthesized by Inductively Coupled Thermal Plasma Process

    Science.gov (United States)

    Kim, Kyou-Hyun; Choi, Hanshin; Han, Chulwoong

    2017-01-01

    We here synthesized a Cu nanoparticle-coated W micropowder using in-situ reactive radio frequency thermal plasma with a blended feedstock of tungsten (W) and copper oxide micropowder. The spherical W micropowder improves the packing density and uniformity of the compacted body. On the other hand, the Cu nanoparticles coated on the W micropowder allow the spherical W powders to be compacted by rigid-die compaction only at 400 MPa. Moreover, homogeneous sintering in both solid state and liquid state occurs even at low Cu contents of 5 wt pct due to the uniformly coated Cu nanoparticles. The effect of W/Cu core/shell structure on the physical properties of sintered W-5 wt pct Cu composite is investigated based on the density, resistivity, and hardness. The results show that homogeneously sintered W-5 wt pct Cu composite well agree with the theoretical values calculated from the rule of mixture.

  17. Core-Shell Structure of Intermediate Precipitates in a Nb-Based Z-Phase Strengthened 12% Cr Steel.

    Science.gov (United States)

    Rashidi, Masoud; Andrén, Hans-Olof; Liu, Fang

    2017-04-01

    In creep resistant Z-phase strengthened 12% Cr steels, MX (M=Nb, Ta, or V, and X=C and/or N) to Z-phase (CrMN, M=Ta, Nb, or V) transformation plays an important role in achieving a fine distribution of Z-phase precipitates for creep strengthening. Atom probe tomography was employed to investigate the phase transformation in a Nb-based Z-phase strengthened trial steel. Using iso-concentration surfaces with different concentration values, and subtracting the matrix contribution enabled us to reveal the core-shell structure of the transient precipitates between MX and Z-phase. It was shown that Z-phase forms by diffusion of Cr into NbN upon ageing, and Z-phase has a composition corresponding to Cr1+x Nb1-x N with x=0.08.

  18. Structural and optical properties of CdO/ZnS core/shell nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Joyce Stella, R.; Thirumala Rao, G.; Pushpa Manjari, V.; Babu, B. [Department of Physics, University College of Sciences, Acharya Nagarjuna University, Nagarjuna Nagar 522510, A.P. (India); Rama Krishna, Ch. [Division of Advanced Materials Science & Engineering, Chonbuk National University, 567, Baekje-daero, Deokjin-gu, Jeonju 561-756 (Korea, Republic of); Ravikumar, R.V.S.S.N., E-mail: rvssn@yahoo.co.in [Department of Physics, University College of Sciences, Acharya Nagarjuna University, Nagarjuna Nagar 522510, A.P. (India)

    2015-04-15

    Graphical abstract: Powder X-ray diffraction pattern of CdO nanopowder and CdO/ZnS nanocomposites. XRD pattern of prepared samples confirm the predominant phase is CdO and small, broad peaks show the ZnS phase in nanocomposites. This XRD data is indexed to cubic crystal system and lattice parameter is calculated as a = 4.6916 Å. After the deposition of ZnS, small blue diffraction peaks are observed for cubic CdO nanostructures. The corresponding lattice cell parameters are evaluated as a = 4.6910 for CdO and a = 5.3735 Å for ZnS. After formation of the CdO–ZnS nanocomposites, the peak intensities of CdO decrease and new peaks due to ZnS are observed. This supports the fact that ZnS particles are deposited on the surface of CdO. These results shows well agreement with standard diffraction data of JCPDS file No. 05-0640 for face centred cubic CdO and file No. 05-0566 for cubic ZnS. From this diffraction data crystallite size, strain and dislocation density are evaluated from Scherrer’s formula and Williamson and Hall. After the deposition of ZnS, increase in particle size and decrease in strain and dislocation density is observed. - Highlights: • CdO/ZnS core/shell nanocomposites were synthesized by a two step wet chemical method. • Powder XRD pattern confirms the cubic phase of the prepared materials. • Red shift is observed in PL spectrum after the deposition of ZnS. - Abstract: CdO/ZnS core/shell nanocomposites have been synthesised at room temperature by a simple wet chemical method. The prepared materials are characterized by XRD, SEM, EDS, FT-IR, UV–Vis and Photoluminescence studies. X-ray diffraction pattern exhibits peaks correspond to cubic phase of CdO and ZnS, the evaluated average crystallite size of prepared materials are in the range of 20–30 nm. The strain and dislocation density are also calculated from XRD studies. Morphology of the samples and their chemical composition are analysed by SEM with EDS. FT-IR spectrum shows the

  19. Core-Shell Structural CdS@SnO₂ Nanorods with Excellent Visible-Light Photocatalytic Activity for the Selective Oxidation of Benzyl Alcohol to Benzaldehyde.

    Science.gov (United States)

    Liu, Ya; Zhang, Ping; Tian, Baozhu; Zhang, Jinlong

    2015-07-01

    Core-shell structural CdS@SnO2 nanorods (NRs) were fabricated by synthesizing SnO2 nanoparticles with a solvent-assisted interfacial reaction and further anchoring them on the surface of CdS NRs under ultrasonic stirring. The morphology, composition, and microstructures of the obtained samples were characterized by field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and nitrogen adsorption-desorption. It was found that SnO2 nanoparticles can be tightly anchored on the surface of CdS NRs, and the thickness of SnO2 shells can be conveniently adjusted by simply changing the addition amount of SnO2 quantum dots. UV-vis diffuse reflectance spectrum indicated that SnO2 shell layer also can enhance the visible light absorption of CdS NRs to a certain extent. The results of transient photocurrents and photoluminescence spectra revealed that the core-shell structure can effectively promote the separation rate of electron-hole pairs and prolong the lifetime of electrons. Compared with the single CdS NRs, the core-shell structural CdS@SnO2 exhibited a remarkably enhanced photocatalytic activity for selective oxidation of benzyl alcohol (BA) to benzaldehyde (BAD) under visible light irradiation, attributed to the more efficient separation of electrons and holes, improved surface area, and enhanced visible light absorption of core-shell structure. The radical scavenging experiments proved that in acetonitrile solution, ·O2- and holes are the main reactive species responsible for BA to BAD transformation, and the lack of ·OH radicals is favorable to obtaining high reaction selectivity.

  20. Designing of luminescent GdPO4:Eu@LaPO4@SiO2 core/shell nanorods: Synthesis, structural and luminescence properties

    Science.gov (United States)

    Ansari, Anees A.; Labis, Joselito P.; Aslam Manthrammel, M.

    2017-09-01

    GdPO4:Eu3+ (core) and GdPO4:Eu@LaPO4 (core/shell) nanorods (NRs) were successfully prepared by urea based co-precipitation process at ambient conditions which was followed by coating with amorphous silica shell via the sol-gel chemical route. The role of surface coating on the crystal structure, crystallinity, morphology, solubility, surface chemistry and luminescence properties were well investigated by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray (EDX) analysis, Fourier Transform Infrared (FTIR), UV-Vis, and photoluminescence spectroscopy. XRD pattern revealed highly purified, well-crystalline, single phase-hexagonal-rhabdophane structure of GdPO4 crystal. The TEM micrographs exhibited highly crystalline and narrow size distributed rod-shaped GdPO4:Eu3+ nanostructures with average width 14-16 nm and typical length 190-220 nm. FTIR spectra revealed characteristic infrared absorption bands of amorphous silica. High absorbance in a visible region of silica modified core/shell/Si NRs in aqueous environment suggests the high solubility along with colloidal stability. The photoluminescence properties were remarkably enhanced after growth of undoped LaPO4 layers due to the reduction of nonradiative transition rate. The advantages of presented high emission intensity and high solubility of core/shell and core/shell/Si NRs indicated the potential applications in monitoring biological events.

  1. Effects of substrate temperature on the growth, structural and optical properties of NiSi/SiC core-shell nanowires

    Science.gov (United States)

    Hamzan, Najwa Binti; Nordin, Farah Nadiah Binti; Rahman, Saadah Abdul; Huang, Nay Ming; Goh, Boon Tong

    2015-07-01

    In this paper we attempt to study the growth of NiSi/SiC core-shell nanowires on Ni-coated glass substrates by hot-wire chemical vapor deposition. The samples were prepared at different substrate temperatures of between 350 and 527 °C to investigate the growth of the nanowires. Ni nanoparticles were used as templates for initially inducing the growth of these core-shell nanowires at substrate temperature as low as 350 °C. The high density of the nanowires was clearly demonstrated at higher substrate temperatures of 450 and 527 °C. These core-shell nanowires were structured by single crystalline NiSi and amorphous SiC as the core and shell of the nanowires respectively. The amorphous SiC shell consisted of SiC nanocolumns within an amorphous matrix. The formation of these high density nanowires showed a noticeable suppression in photoluminescence emissions from the oxygen-related defects and superior optical absorption in visible and limited near infrared regions. The effects of substrate temperatures on growth, optical and structural properties of the nanowires are presented and discussed.

  2. Synthesis and study of structural and magnetic properties of superparamagnetic Fe3O4@SiO2 core/shell nanocomposite for biomedical applications

    Directory of Open Access Journals (Sweden)

    Mitra Helmi Rashid Farimani

    2013-09-01

    Full Text Available   Objective(s: This paper describes coating of magnetite nanoparticles (MNPs with amorphous silica shells.   Materials and Methods: First, magnetite (Fe3O4 NPs were synthesized by co-precipitation method and then treated with stabilizer molecule of trisodium citrate to enhance their dispersibility. Afterwards, coating with silica was carried out via a sol-gel approach in which the electrostatically stabilized MNPs were used as seeds. The samples were characterized by means of X-ray diffraction (XRD, transmission electron microscopy (TEM, Fourier transform infrared (FT-IR spectroscopy and vibrating sample magnetometer (VSM. Results: The results of XRD analysis implied that the prepared nanocomposite consists of two compounds of crystalline magnetite and amorphous silica that formation of their core/shell structure with the shell thickness of about 5 nm was confirmed by TEM images. The magnetic studies also indicated that produced Fe3O4@SiO2 core/shell nanocomposite exhibits superparamagnetic properties at room temperature. Conclusion: These core/shell structure due to having superparamagnetic property of Fe3O4 and unique properties of SiO2, offers a high potential for many biomedical applications.

  3. Dynamic Analysis of Shells

    Directory of Open Access Journals (Sweden)

    Charles R. Steele

    1995-01-01

    Full Text Available Shell structures are indispensable in virtually every industry. However, in the design, analysis, fabrication, and maintenance of such structures, there are many pitfalls leading to various forms of disaster. The experience gained by engineers over some 200 years of disasters and brushes with disaster is expressed in the extensive archival literature, national codes, and procedural documentation found in larger companies. However, the advantage of the richness in the behavior of shells is that the way is always open for innovation. In this survey, we present a broad overview of the dynamic response of shell structures. The intention is to provide an understanding of the basic themes behind the detailed codes and stimulate, not restrict, positive innovation. Such understanding is also crucial for the correct computation of shell structures by any computer code. The physics dictates that the thin shell structure offers a challenge for analysis and computation. Shell response can be generally categorized by states of extension, inextensional bending, edge bending, and edge transverse shear. Simple estimates for the magnitudes of stress, deformation, and resonance in the extensional and inextensional states are provided by ring response. Several shell examples demonstrate the different states and combinations. For excitation frequency above the extensional resonance, such as in impact and acoustic excitation, a fine mesh is needed over the entire shell surface. For this range, modal and implicit methods are of limited value. The example of a sphere impacting a rigid surface shows that plastic unloading occurs continuously. Thus, there are no short cuts; the complete material behavior must be included.

  4. Structures, thermal stability, and melting behaviors of free-standing pentagonal multi-shell Pd-Pt nanowires

    Science.gov (United States)

    Cheng, D.; Hou, M.

    2010-04-01

    Classical molecular dynamics and Metropolis Monte Carlo simulations were carried out to investigate the thermal stability and melting behaviors of free-standing Pd-Pt bimetallic nanowires (NWs) with pentagonal multi-shell-type (PMS-type) structure in the whole composition range. Equilibrium configurations at 100 K are predicted in the semi-grand canonical ensemble. Pd-Pt PMS-type NWs are stable with a multishell structure of alternating Pd and Pt compositions and Pd segregating systematically to the surface. On thermal heating, an interesting composition-dependent structural transformation from the PMS-type to face-centred-cubic (FCC) by overcoming a high energy barrier is observed for Pd-Pt bimetallic NWs before the melting. Consequently, the system energy is decreased. The FCC structure is found more stable than PMS-type over the whole range of composition. The melting of Pd-Pt bimetallic NWs is also studied. It is found to start at the edges, then propagate over the whole surface, and next to the interior. It occurs in a composition-dependent range of temperature.

  5. Error estimation and adaptive mesh refinement for parallel analysis of shell structures

    Science.gov (United States)

    Keating, Scott C.; Felippa, Carlos A.; Park, K. C.

    1994-01-01

    The formulation and application of element-level, element-independent error indicators is investigated. This research culminates in the development of an error indicator formulation which is derived based on the projection of element deformation onto the intrinsic element displacement modes. The qualifier 'element-level' means that no information from adjacent elements is used for error estimation. This property is ideally suited for obtaining error values and driving adaptive mesh refinements on parallel computers where access to neighboring elements residing on different processors may incur significant overhead. In addition such estimators are insensitive to the presence of physical interfaces and junctures. An error indicator qualifies as 'element-independent' when only visible quantities such as element stiffness and nodal displacements are used to quantify error. Error evaluation at the element level and element independence for the error indicator are highly desired properties for computing error in production-level finite element codes. Four element-level error indicators have been constructed. Two of the indicators are based on variational formulation of the element stiffness and are element-dependent. Their derivations are retained for developmental purposes. The second two indicators mimic and exceed the first two in performance but require no special formulation of the element stiffness mesh refinement which we demonstrate for two dimensional plane stress problems. The parallelizing of substructures and adaptive mesh refinement is discussed and the final error indicator using two-dimensional plane-stress and three-dimensional shell problems is demonstrated.

  6. SAPNEW: Parallel finite element code for thin shell structures on the Alliant FX-80

    Science.gov (United States)

    Kamat, Manohar P.; Watson, Brian C.

    1992-11-01

    The finite element method has proven to be an invaluable tool for analysis and design of complex, high performance systems, such as bladed-disk assemblies in aircraft turbofan engines. However, as the problem size increase, the computation time required by conventional computers can be prohibitively high. Parallel processing computers provide the means to overcome these computation time limits. This report summarizes the results of a research activity aimed at providing a finite element capability for analyzing turbomachinery bladed-disk assemblies in a vector/parallel processing environment. A special purpose code, named with the acronym SAPNEW, has been developed to perform static and eigen analysis of multi-degree-of-freedom blade models built-up from flat thin shell elements. SAPNEW provides a stand alone capability for static and eigen analysis on the Alliant FX/80, a parallel processing computer. A preprocessor, named with the acronym NTOS, has been developed to accept NASTRAN input decks and convert them to the SAPNEW format to make SAPNEW more readily used by researchers at NASA Lewis Research Center.

  7. Core-Shell Nanocatalysts Obtained in Reverse Micelles: Structural and Kinetic Aspects

    Directory of Open Access Journals (Sweden)

    Concha Tojo

    2015-01-01

    Full Text Available Ability to control the metal arrangement in bimetallic nanocatalysts is the key to improving their catalytic activity. To investigate how metal distribution in nanostructures can be modified, we developed a computer simulation model on the synthesis of bimetallic nanoparticles obtained in microemulsions by a one-pot method. The calculations allow predicting the metal arrangement in nanoparticle under different experimental conditions. We present results for two couples of metals, Au/Pt (Δε=0.26 V and Au/Ag (Δε=0.19 V, but conclusions can be generalized to other bimetallic pairs with similar difference in standard reduction potentials. It was proved that both surface and interior compositions can be controlled at nanometer resolution easily by changing the initial reactant concentration inside micelles. Kinetic analysis demonstrates that the confinement of reactants inside micelles has a strong effect on the reaction rates of the metal precursors. As a result, the final nanocatalyst shows a more mixed core and a better defined shell as concentration is higher.

  8. Sensitivity of Λ single-particle energies to the ΛN spin-orbit coupling and to nuclear core structure in p-shell and sd-shell hypernuclei

    Science.gov (United States)

    Veselý, P.; Hiyama, E.; Hrtánková, J.; Mareš, J.

    2016-10-01

    We introduce a mean field model based on realistic 2-body baryon interactions and calculate spectra of a set of p-shell and sd-shell Λ hypernuclei - 13ΛC, 17ΛO, 21ΛNe, 29ΛSi and 41ΛCa. The hypernuclear spectra are compared with the results of a relativistic mean field (RMF) model and available experimental data. The sensitivity of Λ single-particle energies to the nuclear core structure is explored. Special attention is paid to the effect of spin-orbit ΛN interaction on the energy splitting of the Λ single particle levels 0p3/2 and 0p1/2. In particular, we analyze the contribution of the symmetric (SLS) and the anti-symmetric (ALS) spin-orbit terms to the energy splitting. We give qualitative predictions for the calculated hypernuclei.

  9. Drug release profile in core-shell nanofibrous structures: a study on Peppas equation and artificial neural network modeling.

    Science.gov (United States)

    Maleki, Mahboubeh; Amani-Tehran, Mohammad; Latifi, Masoud; Mathur, Sanjay

    2014-01-01

    Release profile of drug constituent encapsulated in electrospun core-shell nanofibrous mats was modeled by Peppas equation and artificial neural network. Core-shell fibers were fabricated by co-axial electrospinning process using tetracycline hydrochloride (TCH) as the core and poly(l-lactide-co-glycolide) (PLGA) or polycaprolactone (PCL) as the shell materials. The density and hydrophilicity of the shell polymers, feed rates and concentrations of core and shell phases, the contribution of TCH in core material and electrical field were the parameters fed to the perceptron network to predict Peppas constants in order to derive release pattern. This study demonstrated the viability of the prediction tool in determining drug release profile of electrospun core-shell nanofibrous scaffolds.

  10. Fabrication of and drug delivery by an upconversion emission nanocomposite with monodisperse LaF3:Yb,Er core / mesoporous silica shell structure

    NARCIS (Netherlands)

    Yang, Y.; Qu, Y.; Zhao, J.; Zeng, Q.; Ran, Y.; Zhang, Q.; Kong, X.; Zhang, H.

    2010-01-01

    Monodisperse, uniform, encapsulated mesoporous silicananocomposites with a LaF3:Yb,Er core and a mesoporous silica shell structure, which still exhibit green upconversion photoluminescence (PL) under 980 nm irradiation, have been successfully synthesized and investigated as potential drug delivery s

  11. Robust synthesis of green fuels from biomass-derived ethyl esters over a hierarchically core/shell-structured ZSM-5@(Co/SiO2) catalyst.

    Science.gov (United States)

    Wang, Darui; Wang, Bo; Ding, Yu; Yuan, Qingqing; Wu, Haihong; Guan, Yejun; Wu, Peng

    2017-09-12

    A novel bifunctional ZSM-5@(Co/SiO2) material with a hierarchical core/shell structure was successfully prepared through a simple chemoselective interaction between the crystal surface silica species of zeolite and the external Co(2+) source in basic media, which served as an excellent catalyst in the synthesis of green fuels from biomass-derived ethyl esters.

  12. Hollow-shell-structured nanospheres: a recoverable heterogeneous catalyst for rhodium-catalyzed tandem reduction/lactonization of ethyl 2-acylarylcarboxylates to chiral phthalides.

    Science.gov (United States)

    Liu, Rui; Jin, Ronghua; An, Juzeng; Zhao, Qiankun; Cheng, Tanyu; Liu, Guohua

    2014-05-01

    Chiral organorhodium-functionalized hollow-shell-structured nanospheres were prepared by immobilization of a chiral N-sulfonylated diamine-based organorhodium complex within an ethylene-bridged organosilicate shell. Structural analysis and characterization reveal its well-defined single-site rhodium active center, and transmission electron microscopy images reveal a uniform dispersion of hollow-shell-structured nanospheres. As a heterogenous catalyst, it exhibits excellent catalytic activity and enantioselectivity in synthesis of chiral phthalides by a tandem reduction/lactonization of ethyl 2-acylarylcarboxylates in aqueous medium. The high catalytic performance is attributed to the synergistic effect of the high hydrophobicity and the confined chiral organorhodium catalytic nature. The organorhodium-functionalized nanospheres could be conveniently recovered and reused at least 10 times without loss of catalytic activity. This feature makes it an attractive catalyst in environmentally friendly organic reactions. The results of this study offer a new approach to immobilize chiral organometal functionalities within the hollow-shell-structured nanospheres to prepare materials with high activity in heterogeneous asymmetric catalysis.

  13. The Core/Shell Structure of CdSe/ZnS Quantum Dots Characterized by X-Ray Absorption Fine Spectroscopy

    Directory of Open Access Journals (Sweden)

    Huijing Wei

    2015-01-01

    Full Text Available Understanding the chemical and physical properties of core/shell nanocrystal quantum dots (QDs is key for their use in light-emission applications. In this paper, a single-step injection-free scalable synthetic method is applied to prepare high-quality core/shell QDs with emission wavelengths of 544 nm, 601 nm, and 634 nm. X-ray absorption fine structure spectra are used to determine the core/shell structure of CdSe/ZnS quantum dots. Moreover, theoretical XANES spectra calculated by FEFF.8.20 are used to determine the structure of Se and S compounds. The QD samples displayed nearly spherical shapes with diameters of approximately 3.4 ± 0.5 nm (634 nm, 4.5 ± 0.4 nm (601 nm, and 5.5 ± 0.5 nm (544 nm. With XANES results and MS calculations, it is indicated that sphalerite ZnS capped with organic sulfur ligands should be the shell structure. Wurtzite CdSe is the main core structure with a Cd-Se bond length of 2.3 Å without phase shift. This means that different emission wavelengths are only due to the crystal size with single-step injection-free synthesis. Therefore, single-step injection-free synthesis could generate a nearly ideal core/shell structure of CdSe/ZnS QDs capped with an organic sulfur ligand.

  14. 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...

  15. 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.

  16. 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.

  17. Pulsed laser deposited porous nano-carpets of indium tin oxide and their use as charge collectors in core-shell structures for dye sensitized solar cells.

    Science.gov (United States)

    Garvey, Timothy R; Farnum, Byron H; Lopez, Rene

    2015-02-14

    Porous In2O3:Sn (ITO) films resembling from brush carpets to open moss-like discrete nanostructures were grown by pulsed laser deposition under low to high background gas pressures, respectively. The charge transport properties of these mesoporous substrates were probed by pulsed laser photo-current and -voltage transient measurements in N719 dye sensitized devices. Although the cyclic voltammetry and dye adsorption measurements suggest a lower proportion of electro-active dye molecules for films deposited at the high-end background gas pressures, the transient measurements indicate similar electron transport rates within the films. Solar cell operation was achieved by the deposition of a conformal TiO2 shell layer by atomic layer deposition (ALD). Much of the device improvement was shown to be due to the TiO2 shell blocking the recombination of photoelectrons with the electrolyte as recombination lifetimes increased drastically from a few seconds in uncoated ITO to over 50 minutes in the ITO with a TiO2 shell layer. Additionally, an order of magnitude increase in the electron transport rate in ITO/TiO2 (core/shell) films was observed, giving the core-shell structure a superior ratio of recombination/transport times.

  18. Shell structure underlying the evolution of quadrupole collectivity in S-38 and S-40 probed by transient-field g-factor measurements on fast radioactive beams

    CERN Document Server

    Stuchbery, A E; Brown, B A; Campbell, C M; Cook, J M; Davidson, P M; Davies, A D; Dinca, D C; Gade, A; Liddick, S N; Mantica, P F; Mertzimekis, T J; Müller, W F; Terry, J R; Tomlin, B E; Wilson, A N; Yoneda, K; Zwahlen, H

    2006-01-01

    The shell structure underlying shape changes in neutron-rich nuclei between N=20 and N=28 has been investigated by a novel application of the transient field technique to measure the first-excited state g factors in S-38 and S-40 produced as fast radioactive beams. Details of the new methodology are presented. In both S-38 and S-40 there is a fine balance between the proton and neutron contributions to the magnetic moments. Shell model calculations which describe the level schemes and quadrupole properties of these nuclei also give a satisfactory explanation of the g factors. In S-38 the g factor is extremely sensitive to the occupation of the neutron p3/2 orbit above the N=28 shell gap as occupation of this orbit strongly affects the proton configuration. The g factor of deformed S-40 does not resemble that of a conventional collective nucleus because spin contributions are more important than usual.

  19. Novel structure of TiO2-ZnO core shell rice grain for photoanode of dye-sensitized solar cells

    Science.gov (United States)

    Song, Lixin; Jiang, Qingxu; Du, Pingfan; Yang, Yefeng; Xiong, Jie; Cui, Can

    2014-09-01

    The TiO2-ZnO core shell rice grains are prepared by coaxial electrospinning and calcination. These core shell rice grains have the length of 300-800 nm and the BET surface area of 66.3 m2 g-1. They consist of anatase TiO2 (core) and wurtzite ZnO (shell). Using this novel structure as the photoanodic material, the dye-sensitized solar cells (DSSCs) have the conversion efficiency (η) of 5.31%, which is increased by 23.9% in comparison with that of the DSSCs based on the TiO2 rice grains. This is mainly ascribed to the improvement in both light harvesting efficiency and electron collection efficiency, and the effective suppression of charge recombination.

  20. Structural analysis and design optimization of double shell system for fuel irradiation capsule

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Y. S.; Choi, Y. J.; Choi, M. H.; Rhu, C. H.; Go, J. H.; Hong, S. J.; Lee, H. C. [Chungnam National Univ., Taejeon (Korea)

    2001-04-01

    During irradiation tests, the fuel capsule expect that the high temperature will be occur. Thus, to estimate the structural integrity of fuel capsule during irradiation tests, it is needed to perform structural analysis and to obtain the information of mechanical characteristics for the system. In this study, the structure analysis of the circular capsule is performed using the finite element analysis program, ANSYS and analysis calculation. To obtain the mechanical characteristics of the circular capsule structure such as stresses, critical buckling loads and natural frequencies et al. the static nd model analysis are conducted. The effects of various wall thicknesses of capsule outer tube and support tube for circular capsule are obtained. Also, the effects of boundary conditions and principal materials of the fuel capsule on the structural behavior are investigated. The FE results are compared with the analysis results in case of possible. 13 refs., 34 figs., 10 tabs. (Author)

  1. Clinical Effect of GC Fuji Ⅱ Glass-Ionomer Cement in Repair of Wedge-Shaped Defects%富士Ⅱ玻璃离子充填材料修复楔状缺损的临床疗效观察

    Institute of Scientific and Technical Information of China (English)

    刘晓蕊; 张慧琴; 员战民; 常缨

    2011-01-01

    目的:比较富士Ⅱ玻璃离子与普通玻璃离子充填材料修复楔状缺损的临床疗效.方法:58例患者324颗楔状缺损患牙随机分为2组,分别用富士Ⅱ玻璃离子(实验组)和普通玻璃离子材(对照组)进行修复,观察修复后半年、一年和两年的充填效果.结果:富士Ⅱ玻璃离子和普通玻璃离子充填材料的成功率0.5年分别为98.15%、87.04%;1年分别为93.83%、71.25%;2年分别为89.38%、58.60%,修复后0.5年、1年、2年相比差异均有有显著性,(P<0.01).结论:富士Ⅱ玻璃离子充填材料修复楔状缺损效果好,是充填楔状缺损较理想的材料.%Objective: To compare the clinical effect of GC Fuji II glass-ionomer cement and ordinary glass-ionomer cement for repairing wedge-shaped defects. Methods: Totally 58 teeth were randomly divided into 2 groups, and filled by GC Fuji Ⅱ glass-ionomer cement (experimental group) and ordinary glass-ionomer cement (control group) respectively, which was to compare the clinical effect after 6 months, 1 year, and 2 years. Results: With 0.5 years, the successful rates for both GC Fuji Ⅱ glass-ionomer cement and ordinary glass-ionomer cement are 98.15%, 87.04 respectively; with 1 year, 93.83%, 71.25; with 2 years, 89.38%, 58.60%, there were significant difference if compared after either 0.5 years, 1 year or 2 years (P< 0.01). Conclusion: It exhibits GC Fuji II supior effects to ordinary glass-ionomer cement, that is a relatively ideal restorative material.

  2. Observation of Effect onFilling of 50 CasesWedge Shaped DefectTeeth by Light Cured Composite Resin and Glass Ionomer Cement%光固化复合树脂、玻璃离子水门汀填充牙楔状缺损50例的疗效观察

    Institute of Scientific and Technical Information of China (English)

    马勇

    2016-01-01

    Objective To investigate the clinical efficacyonfilling of 50 caseswedge shaped defectteeth by light cured composite resin and glass ionomer cement.Methods50 cases (186 teeth) with wedge shaped defect in our hospital were selected.They were randomly divided into light cured composite resin and glass ionomer cement joint repair group (observation group),62 teeth, light cured composite resin repair group (control group 1),58 teeth, glass ionomer cement group (control group 2),66 teeth, therapeutic effect of three groups of patients were compared.ResultsAfter 2 years of observation, the success rate of observation group was significantly higher than that of control group 1 and control group 2, the difference was statistically significant (P0.05).ConclusionIt canobtain good therapeutic effect thatwedge shaped defectteeth was repaired by light cured composite resin and glass ionomer cement. This method is worthy to be popularized and applied in clinical practice.%目的:探讨光固化复合树脂联合玻璃离子水门汀填充牙楔状缺损的临床疗效。方法选取本院门诊收治的50例(共186颗)牙楔状缺损患者,随机将其分为光固化复合树脂与玻璃离子水门汀联合修复组(观察组),共62颗,光固化复合树脂修复组(对照1组),共58颗,玻璃离子水门汀修复组(对照2组),共66颗,对三组患者的治疗效果进行比较。结果经2年的修复观察,观察组的修复成功率明显高于对照1组和对照2组,差异具有统计学意义(P0.05)。结论光固化复合树脂联合玻璃离子水门汀填充牙楔状缺损能取得良好的治疗效果,值得在临床推广与应用。

  3. 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......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...

  4. Prevalence of anisotropic shell growth in rare earth core-shell upconversion nanocrystals.

    Science.gov (United States)

    Zhang, Chao; Lee, Jim Yang

    2013-05-28

    Through a series of carefully executed experiments, we discovered the prevalence of anisotropic shell growth in many upconversion NaREF4 systems caused by a combination of factors: selective adsorption of ligands on the core surface due to the core crystal structure, ligand etching, and the lattice mismatch between core and shell components. This could lead to incomplete shell formation in core-shell nanocrystals under certain conditions. Shell growth is always faster in the a and b crystallographic directions than in the c direction. In the case of a larger lattice mismatch between the core and shell, shell growth only occurs in the a and b directions resulting in an oblong core-shell structure. These findings are useful for rationalizing shell-dependent emission properties, understanding the emission mechanisms in complex core-shell nanostructures, and for creating accurate models of core-shell designs for multifunctionality and optimal performance in applications.

  5. Exploring the structural and magnetic properties of TiO2/SnO2 core/shell nanocomposite: An experimental and density functional study

    Science.gov (United States)

    Chetri, Pawan; Basyach, Priyanka; Choudhury, Amarjyoti

    2014-12-01

    TiO2/SnO2 core/shell nanocomposite is prepared via a simple sol-gel method and the properties are compared with the individual TiO2 (core) and SnO2 (shell). The corresponding characterizations are carried out in terms of structural and magnetic properties of TiO2/SnO2, TiO2 and SnO2 nanosystems. Structural properties are studied via XRD, TEM, Raman spectroscopy, FTIR and XPS. Magnetic characterization is performed by measuring Moment vs. Applied Field for all the samples and Moment vs. Temperature for TiO2/SnO2 core/shell nanocomposite. We also went for a better insight with the help of theoretical measures. First principle calculations have been executed using “Density Functional Theory” (DFT)-based MedeA VASP package to compare the results of TiO2/SnO2 with TiO2 (1 1 0) and SnO2 (1 1 0) surface calculations and its effect on the magnetic nature of the specific nanoparticles. XRD, RAMAN and FTIR gave indirect evidence of formation of core shell nanostructure while TEM micrographs provide the direct evidence of formation of core shell nanostructure. The magnetic study shows a higher saturation magnetization for the core/shell nanostructure compared to pristine TiO2 and SnO2. In this report, we have attempted to relate this experimental observation with the results of the first principle calculations.

  6. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  8. Immobilized lipase on core-shell structured Fe3O4-MCM-41 nanocomposites as a magnetically recyclable biocatalyst for interesterification of soybean oil and lard.

    Science.gov (United States)

    Xie, Wenlei; Zang, Xuezhen

    2016-03-01

    A core-shell structured Fe3O4-MCM-41 nanocomposite was prepared by means of a surfactant-directed sol-gel process. Candida rugosa lipase was then bound to the magnetic core-shell material by using glutaraldehyde as a cross-linking reagent. The as-prepared Fe3O4-MCM-41 support and the immobilized lipase were characterized in detail using enzyme activity assays, TEM, XRD, FTIR, VSM and nitrogen adsorption-desorption techniques. Results showed that the magnetite nanoparticles were coated with the MCM-41 silica with the formation of core-shell structured materials, and the lipase was successfully immobilized on the core-shell structured support. The catalytic performance of the bound lipase was tested in the interesterification of lard and soybean oil. It was shown that the immobilized lipase had a better catalytic activity towards the interesterification reaction. The slip melting point of the final product was lower than that of the original blend, and the interesterification led to an obvious variation in the microstructure of the product.

  9. 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)

  10. Discovery of Shell-Like Radio-Structure in SN 1993J

    Science.gov (United States)

    Marcaide, J.; Alberdi, A.; Ros, E.; Diamond, P.; Schmidt, B.; Shapiro, I.; Baath, L.; De Bruyn, G.; Elosegui, P.; Guirado, J.; Davis, R.; Jones, D.; Krichbaum, T.; Manntovani, F.; Preston, R.; Ratner, M.; Rius, A.; Rogers, A.; Schilizzi, R.; Trigilio, C.; Whitney, A.; Witzel, A.; Zensus, A.

    1994-01-01

    The radio-luminous supernova SN 1993J in M81 offers an unprecedented opportunity to study with high linear resolution the details of the growth of a supernova radio structure by means of the VLBI technique.

  11. Structure and Property of Cashew Nut Shell Flour/PVC Composite%腰果壳粉/PVC复合材料的结构和性能

    Institute of Scientific and Technical Information of China (English)

    肖建平; 岑兰; 陈福林; 周彦豪

    2013-01-01

    通过采用六次甲基四胺对腰果壳粉进行改性,并制备了腰果壳粉/聚氯乙烯(PVC)复合材料.研究改性前后腰果壳粉的用量对复合材料力学性能、耐水性和加工性能的影响,并用扫描电镜(SEM)观察了断面形貌.结果表明:随着不同腰果壳粉用量的增加,复合材料的拉伸强度、冲击强度、弯曲强度呈先上升后下降的趋势,当腰果壳粉用量为5 ~10份时最佳;添加质量分数为5%的六次甲基四胺改性腰果壳粉时,复合材料的物理力学性能、耐水性提高.%The cashew nut shell flour was modified by hexamethylene tetramine( C6H12 N4) , cashew nut shell flour/PVC composite were prepared. The effects of varieties content of cashew nut shell flour on mechanical properties, water proof and proceeding fluidity of cashew nut shell flour/PVC composite were investigated. The morphology structure of cashew nut shell flour/PVC composite was observed by SEM. Results showed that with increasing the amount of cashew nut shell flour or modified cashew nut shell flour,the properties of tensile strength,impact strength,bending strength were increased at first and then decreased,composite with excellent properties was obtained by the content of cashew nut shell flour being 5 ~ 10 phr. When cashew nut shell flour was modified by C6H12N4,whose ratio was 5 % (by mass) , mechanical properties and water proof of composite were increased.

  12. Plate/shell structure topology optimization of orthotropic material for buckling problem based on independent continuous topological variables

    Science.gov (United States)

    Ye, Hong-Ling; Wang, Wei-Wei; Chen, Ning; Sui, Yun-Kang

    2017-03-01

    The purpose of the present work is to study the buckling problem with plate/shell topology optimization of orthotropic material. A model of buckling topology optimization is established based on the independent, continuous, and mapping method, which considers structural mass as objective and buckling critical loads as constraints. Firstly, composite exponential function (CEF) and power function (PF) as filter functions are introduced to recognize the element mass, the element stiffness matrix, and the element geometric stiffness matrix. The filter functions of the orthotropic material stiffness are deduced. Then these filter functions are put into buckling topology optimization of a differential equation to analyze the design sensitivity. Furthermore, the buckling constraints are approximately expressed as explicit functions with respect to the design variables based on the first-order Taylor expansion. The objective function is standardized based on the second-order Taylor expansion. Therefore, the optimization model is translated into a quadratic program. Finally, the dual sequence quadratic programming (DSQP) algorithm and the global convergence method of moving asymptotes algorithm with two different filter functions (CEF and PF) are applied to solve the optimal model. Three numerical results show that DSQP&CEF has the best performance in the view of structural mass and discretion.

  13. Synchrotron-based crystal structure, associated morphology of snail and bivalve shells by X-ray diffraction

    Science.gov (United States)

    Rao, D. V.; Gigante, G. E.; Kumar, Y. Manoj; Cesareo, R.; Brunetti, A.; Schiavon, N.; Akatsuka, T.; Yuasa, T.; Takeda, T.

    2016-10-01

    Synchrotron-based high-resolution X-ray powder diffraction spectra from the body parts of a snail and bivalve (CaCO3), have been recorded with Pilatus area detector. Experiments were performed at Desy, Hamburg, Germany, utilizing the Resonant and Diffraction beamline (P9), with 15 keV X-rays (λ=0.82666 Å). The external shell of these living organisms, is composed of calcium carbonate, which carries strong biological signal. It consists of some light elements, such as, Ca, C and O, which constitute part of the soft tissue and other trace elements. The knowledge of these diffraction patterns and hence the understanding of structures at molecular level are enormous. The application of synchrotron radiation to powder diffraction is well suited for samples of biological nature via changes in their patterns and also to investigate crystallographic phase composition. With the use of Rietveld refinement procedure, to the high-resolution diffraction spectra, we were able to extract the lattice parameters of orthorhombic polymorph of CaCO3, the most abundant mineral produced by these living organisms. The small size of the crystallite is a very important factor related to the biological structure. The natural model presents a combination of organic and inorganic phases with nanometer size. For the present study, we also used the scanning electron microscopy (SEM) to explore the associated morphology of the snail and bivalve.

  14. Elastic platonic shells.

    Science.gov (United States)

    Yong, Ee Hou; Nelson, David R; Mahadevan, L

    2013-10-25

    On microscopic scales, the crystallinity of flexible tethered or cross-linked membranes determines their mechanical response. We show that by controlling the type, number, and distribution of defects on a spherical elastic shell, it is possible to direct the morphology of these structures. Our numerical simulations show that by deflating a crystalline shell with defects, we can create elastic shell analogs of the classical platonic solids. These morphologies arise via a sharp buckling transition from the sphere which is strongly hysteretic in loading or unloading. We construct a minimal Landau theory for the transition using quadratic and cubic invariants of the spherical harmonic modes. Our approach suggests methods to engineer shape into soft spherical shells using a frozen defect topology.

  15. Numerical simulation and transonic wind-tunnel test for elastic thin-shell structure considering fluid-structure interaction

    Institute of Scientific and Technical Information of China (English)

    Yan Yunju; Xi Zhuyou; Zhang Shanzhi

    2015-01-01

    Aerodynamic force can lead to the strong structural vibration of flying aircraft at a high speed. This harmful vibration can bring damage or failure to the electronic equipment fixed in air-craft. It is necessary to predict the structural dynamic response in the design course. This paper pre-sents a new numerical algorithm and scheme to solve the structural dynamics responses when considering fluid–structure interaction (FSI). Numerical simulation for a free-flying structural model in transonic speed is completed. Results show that the small elastic deformation of the struc-ture can greatly affect the FSI. The FSI vibration tests are carried out in a transonic speed wind-tunnel for checking numerical theory and algorithms, and the wind-tunnel test results well accord with that of the numerical simulation. This indicates that the presented numerical method can be applied to predicting the structural dynamics responses when containing the FSI.

  16. 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.

  17. Seasonal changes of sperm storage and correlative structures in male and female soft-shelled turtles, Trionyx sinensis.

    Science.gov (United States)

    Xiangkun, Han; Li, Zhang; Meiying, Li; Huijun, Bao; Nainan, Hei; Qiusheng, Chen

    2008-11-01

    Reproductive ducts of male and female soft-shelled turtles, Trionyx sinensis were examined throughout the year (March, May, September, December) using brightfield and electron microscopes (TEM and SEM), to determine the location and histomorphological characteristics of sperm storage structures as well as their changes at different phases of the seasonal reproductive cycle. Sperm stored in the epididymis were also examined. In the male, spermatogenesis is initiated in spring (May), and then the mature sperm are released in autumn as an episodic event. Spermatogenesis is inactive in winter. However, in this species, the epididymis contains sperm throughout the entire year. Sperm observed in the epididymis are intact and some structures are uniquely different from other reptiles, and is characterized by 35-40 concentric mitochondria with a dense core in the centre. Many glycogen granules are observed in the cytoplasm of the midpiece. However, the epithelial cell type of epididymal duct change in different seasons. The cells are fully developed with a highly secretory activity in September. The materials secreted from the epithelium might have the function as nourishment for the stored sperm. Sperm storage structures in the form of tubules are observed in the wall of the isthmus of the oviduct in hibernating females but are absent in the groups of May and September. These tubules develop either by folding or fusion of the oviductal mucosal folds and are lined by both ciliated and secretory cells. These tubules might provide a microenvironment for the sperm to enable its long-term storage. After being separated 4 months (December-March) from the male, sperm are observed in the tubules of the isthmus of the oviduct. The unique character of the sperm combined with the special sperm storage structures enable the sperm to maintain fertility and activity during their storage.

  18. 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.

  19. 玻璃离子水门汀、光固化复合树脂、流动树脂修复牙体浅型楔状缺损的疗效性%Curative Effect of Glass Sonomer Cement, Light-Cured Composite Resin and Flowable Resin in the Dental Repair of Wedge-Shaped Defect

    Institute of Scientific and Technical Information of China (English)

    李文进

    2015-01-01

    Objective:To compare the clinical efficacy of glass sonomer cement, light-cured composite resin and flowable resin in the dental repair of wedge-shaped defect.Method:90 patients with wedge-shaped defect in our dental clinic were selected from January 2010 to May 2014 and they were randomly divided into three groups, 30 cases in each group. Group A was given glass sonomer cement, group B adopted light-cured composite resin and group C was given the flowable resin. After 1 year of follow-up visits, the success rate of dental repair, loss rate of materials, incidence rate of irritation symptom of dental pulp and incidence rate of secondary caries of three groups were compared.Result: In 1 year, group A had 6 cases with loss of materials,group B had 4 cases and group C had 1 case,the loss rate of materials of group A was significantly higher than that of group C, the difference was statistically significant(P0.05).The incidence rate of irritation symptom of dental pulp of three groups was respectively 10.0%,40.0% and 3.3%,compared group A and C, the difference was not statistically significant(P>0.05)The rate of Group B was significantly higher than that of Group A and Group B, the difference was statistically significant(P0.05).Compared 3 months and 1 weeks after repair, the periodontal index of group B and group C were significantly reduced, the differences were statistically significant (P0.05).Conclusion:The flowable resin is featured as great adhesion, less irritation, ability of filling in the tooth edge, reduction of permeability and fewer damages for periodontal tissues. It has a high success rate of dental repair. It can be promoted and applied in clinical treatment.%目的:对玻璃离子水门汀、光固化复合树脂、流动树脂三种材料修复牙体浅型楔状缺损的临床疗效进行对比,并做出评价。方法:选取2010年1月-2014年5月本院口腔科门诊收治的牙体浅型楔状缺损患者90例为研究对象,将患者

  20. 纤维桩对穿髓型楔状缺损抗折性修复的临床对比观察%Clinical comparative study on anti-fracture effects of fiber post in severe wedge-shaped defect

    Institute of Scientific and Technical Information of China (English)

    王勤波; 戴荣烽

    2014-01-01

    目的:针对穿髓型楔状缺损牙颈部抗力薄弱易折断的潜在隐患,评价不同修复术式对牙颈部抗折性能的临床效果。方法:临床随机选择穿髓型楔状缺损患者48例,牙合面完整,男性20例,女性28例,年龄45-73岁。其中第一前磨牙28例(上颌19例,下颌9例),第二前磨牙9例(上颌6例,下颌3例);尖牙11例(上颌8例,下颌3例)。在牙合面开髓根管治疗后,将所有患者随机分为A、 B两组各24颗牙,以2种术式分别进行修复。 A组:牙合面及楔状缺损处以Filtek Z350 XT纳米树脂完成修复; B组:根管纤维桩粘固后牙合面及楔状缺损处以Filtek Z350 XT纳米树脂完成修复。结果:临床观察2年, A组出现6例颈部折断, B组未出现颈部折断,经卡方检验连续校正公式计算,χ2=4.68, P<0.05,说明是否使用纤维桩修复与牙颈部折断间有统计学差异,使用纤维桩可增强牙颈部抗折断力。结论:在穿髓型楔状缺损根管内粘固玻璃纤维桩的一端,再以复合树脂将纤维桩的另一端与牙冠粘接,使纤维桩、树脂、整个牙齿(冠与根)三者整合为一体,不但增强了颊颈部修复体的固位,更提高了牙颈部的抗折性能,是一种合理、微创的牙颈部抗折修复形式,较好地体现了整体修复理念。%Objective:Based on the potential risk of the weakness of the severe wedge-shaped defect with exposed pulp, to evaluate the clinical efficacy of cervical anti-fracture resistance using different techniques. Methods: 48 patients, 20 males and 28 females, aged between 45 to 73 years old, with severe wedge-shaped defect, exposed pulp, and intact occlusal surfaces were enrolled to this study. 28 cases were the first premolar (19 cases maxillary and 9 cases mandibular). 9 cases were the second premolar (6 cases maxillary and 3 cases mandibular). 11 cases were the canines (8 cases maxillary and 3 cases mandibular

  1. On the Half Shell: An Introduction to Oysters and Their Unique Structures and Function

    Science.gov (United States)

    Frederick, J. Adam; Haines, Sarah; Romano, Christina; Takacs, Jacqueline

    2017-01-01

    The eastern oyster, "Crassostrea virginica," is an ecologically and economically important species in Chesapeake Bay. Oysters are ecologically unique in the Chesapeake Bay because they build a structure known as a bar or reef by attaching to one another over a 45 long period of time. They have been coined the "Ecological Engineers…

  2. Structural Performance of Fiber-Placed, Variable-Stiffness Composite Conical and Cylindrical Shells

    NARCIS (Netherlands)

    Blom, A.W.

    2010-01-01

    The use of fiber-reinforced composites in aerospace structures has increased dramatically over the past decades. The high specific strength and stiffness, the tailorability, and the possibilities to integrate parts and reduce the number of fasteners give composites an advantage over metals. Automati

  3. On the Half Shell: An Introduction to Oysters and Their Unique Structures and Function

    Science.gov (United States)

    Frederick, J. Adam; Haines, Sarah; Romano, Christina; Takacs, Jacqueline

    2017-01-01

    The eastern oyster, "Crassostrea virginica," is an ecologically and economically important species in Chesapeake Bay. Oysters are ecologically unique in the Chesapeake Bay because they build a structure known as a bar or reef by attaching to one another over a 45 long period of time. They have been coined the "Ecological Engineers…

  4. Structural Performance of Fiber-Placed, Variable-Stiffness Composite Conical and Cylindrical Shells

    NARCIS (Netherlands)

    Blom, A.W.

    2010-01-01

    The use of fiber-reinforced composites in aerospace structures has increased dramatically over the past decades. The high specific strength and stiffness, the tailorability, and the possibilities to integrate parts and reduce the number of fasteners give composites an advantage over metals.

  5. Size dependent structural, vibrational and magnetic properties of BiFeO{sub 3} and core-shell structured BiFeO{sub 3}@SiO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Chauhan, Sunil, E-mail: sunilchauhanjiit@gmail.com; Kumar, Manoj, E-mail: sunilchauhanjiit@gmail.com; Chhoker, Sandeep, E-mail: sunilchauhanjiit@gmail.com; Katyal, S. C., E-mail: sunilchauhanjiit@gmail.com [Department of Physics and Materials Science and Engineering, Jaypee Institute of Information Technology, Noida- 201307 (India)

    2014-04-24

    Bulk BiFeO{sub 3}, BiFeO{sub 3} nanoparticles and core-shell structured BiFeO{sub 3}@SiO{sub 2} nanoparticles were synthesized by solid state reaction method, sol-gel and Stöber process (SiO{sub 2} shell) respectively. Transmission electron microscopy image confirmed the core-shell structure of BiFeO{sub 3}@SiO{sub 2} nanoparticles with BiFeO3 core ∼50-90 nm and SiO{sub 2} shell ∼16 nm. X-ray diffraction and FTIR spectroscopy results showed the presence of distorted rhombohedral structure with R3c space group in all three samples. The magnetic measurement indicated the existence of room-temperature weak ferromagnetism in core-shell BiFeO{sub 3}@SiO{sub 2} nanoparticles and BiFeO3 nanoparticles, whereas bulk BiFeO{sub 3} showed antiferromagnteic nature. Electron Spin Resonance results confirmed the enhancement in magnetic properties of coreshell structured BiFeO{sub 3}@SiO{sub 2} nanoparticles in comparison with BiFeO{sub 3} nanoparticles and bulk BiFeO{sub 3}.

  6. Test Results of LARP 3.6 m Nb3Sn Racetrack Coils Support by Full-length and Segmented Shell Structures

    Energy Technology Data Exchange (ETDEWEB)

    Muratore, Joseph F.; Ambrosio, Giorgio; Anerella, Michael; Barzi, Emanuela; Bossert, Rodger; Caspi, Shlomo; Cheng, D. W.; Cozzolino, John; Dietderich, Daniel R.; Escallier, John; Feher, Sandor; Felice, Helene; Ferracin, Paolo; Ganetis, George; Ghosh, Arup K.; Gupta, Ramesh C.; Hafalia, A. R.; Hannaford, C. R.; Joshi, Piyush; Kovach, Paul; Lietzke, A. F.; Louie, Wing; Marone, Andrew; McInturff, Al D.; Nobrega, F.; Sabbi, GianLuca; Schmalzle, Jesse; Thomas, Richard; Turrioni, Daniele; Wanderer, Peter

    2008-08-17

    As part of the LHC Accelerator Research Program (LARP) to build a high performance quadrupole magnet with Nb{sub 3}Sn conductor, a pair of 3.6 m-long Nb{sub 3}Sn racetrack coils has been made at Brookhaven National Laboratory (BNL) and installed in two shell-type support structures built by Lawrence Berkeley National Laboratory (LBL). These magnet assemblies have been tested at 4.5 K at BNL to gauge the effect of extended length and prestress on the mechanical performance of the long structure compared to earlier short models. This paper presents the results of quench testing and compares the overall performance of the two versions of the support structure. We also summarize the shell strain measurements and discuss the variation of quench current with ramp rate.

  7. Probing and extracting the structure of vibrating SF6 molecules with inner-shell photoelectrons

    Science.gov (United States)

    Nguyen, Ngoc-Ty; Lucchese, R. R.; Lin, C. D.; Le, Anh-Thu

    2016-06-01

    We propose a scheme for probing the structure of vibrating molecules with photoelectrons generated from ultrashort soft-x-ray pulses. As an example we analyze below-100-eV photoelectrons liberated from the S (2 p ) orbital of vibrating SF6 molecules to image very small structural changes of molecular vibration. In particular, photoionization cross sections and photoelectron angular distributions (PAD) at nonequilibrium geometries can be retrieved accurately with photoelectrons near the shape resonance at 13 eV. This is achieved with a pump-probe scheme, in which the symmetric stretch mode is first Raman excited predominantly by a relatively short laser pulse and then later probed at different time delays by a few-femtosecond soft-x-ray pulse with photon energy near 200 eV.

  8. The contribution of off-shell gluons to the longitudinal structure function F{sub L}

    Energy Technology Data Exchange (ETDEWEB)

    Kotikov, A.V. [Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Lipatov, A.V. [Department of Physics, Lomonosov Moscow State University, 119899 Moscow (Russian Federation); Zotov, N.P. [Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, 119992 Moscow (Russian Federation)

    2003-03-01

    We present the results for the structure function F{sub L} for a gluon target having a non-zero transverse momentum square at order {alpha}{sub s}. The results of a double convolution (with respect to the Bjorken variable x and the transverse momentum) of the perturbative part and the unintegrated gluon densities are compared with recent experimental data for F{sub L} at low x values and with the predictions of other approaches. (orig.)

  9. Structural Performance of Fiber-Placed, Variable-Stiffness Composite Conical and Cylindrical Shells

    OpenAIRE

    Blom, A. W.

    2010-01-01

    The use of fiber-reinforced composites in aerospace structures has increased dramatically over the past decades. The high specific strength and stiffness, the tailorability, and the possibilities to integrate parts and reduce the number of fasteners give composites an advantage over metals. Automation of the production process enables large-scale production of composites in a repeatable, reliable fashion. Fiber-reinforced composite laminates are traditionally made of 0◦, 90◦ and ±45◦ plies. A...

  10. A numerical approach for simulating fluid structure interaction of flexible thin shells undergoing arbitrarily large deformations in complex domains

    Energy Technology Data Exchange (ETDEWEB)

    Gilmanov, Anvar, E-mail: agilmano@umn.edu [Saint Anthony Falls Laboratory, University of Minnesota, Minneapolis, MN 55414 (United States); Le, Trung Bao, E-mail: lebao002@umn.edu [Saint Anthony Falls Laboratory, University of Minnesota, Minneapolis, MN 55414 (United States); Sotiropoulos, Fotis, E-mail: fotis@umn.edu [Saint Anthony Falls Laboratory, University of Minnesota, Minneapolis, MN 55414 (United States); Department of Civil, Environmental and Geo-Engineering, University of Minnesota, Minneapolis, MN 55414 (United States)

    2015-11-01

    We present a new numerical methodology for simulating fluid–structure interaction (FSI) problems involving thin flexible bodies in an incompressible fluid. The FSI algorithm uses the Dirichlet–Neumann partitioning technique. The curvilinear immersed boundary method (CURVIB) is coupled with a rotation-free finite element (FE) model for thin shells enabling the efficient simulation of FSI problems with arbitrarily large deformation. Turbulent flow problems are handled using large-eddy simulation with the dynamic Smagorinsky model in conjunction with a wall model to reconstruct boundary conditions near immersed boundaries. The CURVIB and FE solvers are coupled together on the flexible solid–fluid interfaces where the structural nodal positions, displacements, velocities and loads are calculated and exchanged between the two solvers. Loose and strong coupling FSI schemes are employed enhanced by the Aitken acceleration technique to ensure robust coupling and fast convergence especially for low mass ratio problems. The coupled CURVIB-FE-FSI method is validated by applying it to simulate two FSI problems involving thin flexible structures: 1) vortex-induced vibrations of a cantilever mounted in the wake of a square cylinder at different mass ratios and at low Reynolds number; and 2) the more challenging high Reynolds number problem involving the oscillation of an inverted elastic flag. For both cases the computed results are in excellent agreement with previous numerical simulations and/or experiential measurements. Grid convergence tests/studies are carried out for both the cantilever and inverted flag problems, which show that the CURVIB-FE-FSI method provides their convergence. Finally, the capability of the new methodology in simulations of complex cardiovascular flows is demonstrated by applying it to simulate the FSI of a tri-leaflet, prosthetic heart valve in an anatomic aorta and under physiologic pulsatile conditions.

  11. A numerical approach for simulating fluid structure interaction of flexible thin shells undergoing arbitrarily large deformations in complex domains

    Science.gov (United States)

    Gilmanov, Anvar; Le, Trung Bao; Sotiropoulos, Fotis

    2015-11-01

    We present a new numerical methodology for simulating fluid-structure interaction (FSI) problems involving thin flexible bodies in an incompressible fluid. The FSI algorithm uses the Dirichlet-Neumann partitioning technique. The curvilinear immersed boundary method (CURVIB) is coupled with a rotation-free finite element (FE) model for thin shells enabling the efficient simulation of FSI problems with arbitrarily large deformation. Turbulent flow problems are handled using large-eddy simulation with the dynamic Smagorinsky model in conjunction with a wall model to reconstruct boundary conditions near immersed boundaries. The CURVIB and FE solvers are coupled together on the flexible solid-fluid interfaces where the structural nodal positions, displacements, velocities and loads are calculated and exchanged between the two solvers. Loose and strong coupling FSI schemes are employed enhanced by the Aitken acceleration technique to ensure robust coupling and fast convergence especially for low mass ratio problems. The coupled CURVIB-FE-FSI method is validated by applying it to simulate two FSI problems involving thin flexible structures: 1) vortex-induced vibrations of a cantilever mounted in the wake of a square cylinder at different mass ratios and at low Reynolds number; and 2) the more challenging high Reynolds number problem involving the oscillation of an inverted elastic flag. For both cases the computed results are in excellent agreement with previous numerical simulations and/or experiential measurements. Grid convergence tests/studies are carried out for both the cantilever and inverted flag problems, which show that the CURVIB-FE-FSI method provides their convergence. Finally, the capability of the new methodology in simulations of complex cardiovascular flows is demonstrated by applying it to simulate the FSI of a tri-leaflet, prosthetic heart valve in an anatomic aorta and under physiologic pulsatile conditions.

  12. The structure of the spherical tensor forces in the USD and GXPF1A shell model Hamiltonians

    Institute of Scientific and Technical Information of China (English)

    WANG Han-Kui; GAO Zao-Chun; CHEN Yong-Shou; GUO Jian-You; CHEN Yong-Jing; TU Ya

    2011-01-01

    The realistic shell model Hamiltonians, USD and GXPF1A, have been transformed from the particle-particle (normal) representation to the particle-hole representation (multipole-multipole)by using the known formulation in Ref. [1].The obtained multipole-multipole terms were compared with the known spherical tensor forces, including the coupled ones. It is the first time the contributions of the coupled tensor forces to the shell model Hamiltonian have been investigated. It has been shown that some coupled-tensor forces, such as [r2Y2σ]1,also give important contributions to the shell model Hamiltonian.

  13. Nitrogen-Doped Yolk-Shell-Structured CoSe/C Dodecahedra for High-Performance Sodium Ion Batteries.

    Science.gov (United States)

    Zhang, Yifang; Pan, Anqiang; Ding, Lin; Zhou, Zilong; Wang, Yaping; Niu, Shaoyu; Liang, Shuquan; Cao, Guozhong

    2017-02-01

    In this work, nitrogen-doped, yolk-shell-structured CoSe/C mesoporous dodecahedra are successfully prepared by using cobalt-based metal-organic frameworks (ZIF-67) as sacrificial templates. The CoSe nanoparticles are in situ produced by reacting the cobalt species in the metal-organic frameworks with selenium (Se) powder, and the organic species are simultaneously converted into nitrogen-doped carbon material in an inert atmosphere at temperatures between 700 and 900 °C for 4 h. For the composite synthesized at 800 °C, the carbon framework has a relatively higher extent of graphitization, with high nitrogen content (17.65%). Furthermore, the CoSe nanoparticles, with a size of around 15 nm, are coherently confined in the mesoporous carbon framework. When evaluated as novel anode materials for sodium ion batteries, the CoSe/C composites exhibit high capacity and superior rate capability. The composite electrode delivers the specific capacities of 597.2 and 361.9 mA h g(-1) at 0.2 and 16 A g(-1), respectively.

  14. Metal-based magnetic fluids with core-shell structure FeB@SiO2 amorphous particles.

    Science.gov (United States)

    Yu, Mengchun; Bian, Xiufang; Wang, Tianqi; Wang, Junzhang

    2017-09-27

    FeB@SiO2 amorphous particles were firstly introduced into Ga85.8In14.2 alloys to prepare metal-based magnetic fluids. The morphology of the FeB amorphous particles is spherical with an average particle size of about 190 nm. The shape of the particles is regular and the particle size is homogeneous. Stable core-shell structure SiO2 modified FeB amorphous particles are obtained and the thickness of the SiO2 coatings is observed to be about 40 nm. The results of VSM confirm that the saturation magnetization of the FeB amorphous particles is 131.5 emu g(-1), which is almost two times higher than that of the Fe3O4 particles. The saturation magnetization of the FeB@SiO2 amorphous particles is 106.9 emu g(-1), an approximate decrease of 18.7% due to the non-magnetic SiO2 coatings. The results from the torsional oscillation viscometer show that the metal-based magnetic fluids with FeB amorphous particles exhibit a desirable high temperature performance and are ideal candidates for high temperature use.

  15. Structural and magnetic properties of nanosized iron-polyoxocarbosilane core-shell composites prepared by laser pyrolysis

    Science.gov (United States)

    Alexandrescu, R.; Morjan, I.; Dumitrache, F.; Pola, J.; Vorlicek, V.; Marysko, M.; Gavrila, L.; Scarisoreanu, M.; Voicu, I.; Sandu, I.; Fleaca, C.; Popovici, E.; Prodan, G.

    2007-03-01

    Because of their quantum-scale dimensions, nanoparticles exhibit properties different from those of the bulk. As a result of their unique properties, numerous efforts have been made to disperse nanoparticles in polymers to enhance or modify their structural and magnetic properties. A new in situ synthesis method was used to incorporate small iron nanoparticles into a polyoxocarbosilane polymer matrix. Nano-magnetic iron-based composites were obtained by a one-step procedure consisting of the IR laser co-pyrolysis of a sensitized (with ethylene) gaseous mixture containing gaseous iron pentacarbonyl and hexamethyldisiloxane in argon. The simultaneously occurring formation of iron from iron pentacarbonyl and that of organosilicon polymer from hexamethyldisiloxane yield iron nanoparticles surrounded by an organosilicon polymer shell. The particles become superficially oxidized in the atmosphere. They were characterized by Raman analysis, electron microscopy and magnetic measurements. The properties of the nanocomposite particles depend on the experimental synthesis parameters such as flow rates of precursors, total pressure and laser power. Magnetization curves, exchange bias Hex at T = 5 K and AC susceptibility were studied in the temperature range 5-400 K. It was found that the nanocomposite should be in a ferromagnetic blocked state with a minor superparamagnetic contribution of the smallest nanoparticles.

  16. 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

  17. Local atomic structure of solid solutions with overlapping shells by EXAFS: The regularization method

    Energy Technology Data Exchange (ETDEWEB)

    Babanov, Yu.A., E-mail: babanov@imp.uran.ru [M.N. Miheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, Ekaterinburg 620990 (Russian Federation); Ponomarev, D.A.; Ustinov, V.V. [M.N. Miheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, Ekaterinburg 620990 (Russian Federation); Baranov, A.N. [M.V. Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Zubavichus, Ya.V. [Russian Research Centre “Kurchatov Institute”, 123182 Moscow (Russian Federation)

    2016-08-15

    Highlights: • A method for determining bond lengths from combined EXAFS spectra for solid oxide solutions is proposed. • We have demonstrated a high resolution in r-space of close spacing atoms in the Periodical Table. • These results were obtained without any assumptions concerning interatomic distances for multi-component systems. • Coordinates ions for the solid solution with rock salt structure are determined. - Abstract: The regularization method of solving ill-posed problem is used to determine five partial interatomic distances on the basis of combined two EXAFS spectra. Mathematical algorithm and experimental results of the EXAFS analysis for Ni{sub c}Zn{sub 1−c}O (c = 0.0, 0.3, 0.5, 0.7, 1.0) solid solutions with the rock salt (rs) crystal structure are discussed. Samples were synthesized from the binary oxide powders at pressure of 7.7 GPa and temperatures 1450–1650 K. The measurements were performed using synchrotron facilities (Russian Research Centre “Kurchatov Institute”, Moscow). The Ni and Zn K absorption spectra were recorded in transmission mode under room temperature. It is shown, the ideal rock salt lattice is distorted and long-range order exists only in the average (Vegard law). In order to determine coordinates ions for the solid solution with rock salt structure, we used the Pauling model. The simulation is performed for 343,000 cluster of oxide ions. The distribution functions for ions (Ni−O, Ni−Ni, Ni−Zn, Zn−Zn, Zn−O, O−O) depending on the distance are obtained. The width of the Gaussian distribution function is determined by the difference of the radii of the metal ions. The results are consistent with the data both X-ray diffraction and the EXAFS spectroscopy.

  18. 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)

  19. Self-construction of core-shell structure by metallofullerene-containing polymer.

    Science.gov (United States)

    Bai, Xiaojuan; Yue, Dongmei; Zhao, Shixiong; Dong, Jinquan; Yang, Limei; Ibrahim, Kurash; Wang, Jiaou; Yang, Shangyuan; Hao, Jian; Hu, Zhongbo; Sun, Baoyun

    2011-03-01

    Metallofullerene Gd@C82 offers the opportunity to produce novel and advanced polymer-based nanocomposite materials. In this work, we reported the synthesis of novel Gd@C82-containing copolymers with the optimum condition found by changing the temperature, initiator and fullerene contents of C60-PS. The developed materials, based on polystyrene, displayed unique nanostructures which were confirmed by many measurements (GPC, AFM, SEM, TGA/DSC and NEXAFS analysis). The mechanism, stability and structure of Gd@C82-containing copolymer were discussed. This approach offers a new possibility of optimizing the polymer performance with metallofullerene.

  20. 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.)