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Sample records for 8-node solid shell

  1. Nonlinear shell analyses of the space shuttle solid rocket boosters

    NASA Technical Reports Server (NTRS)

    Knight, Norman F., Jr.; Gillian, Ronnie E.; Nemeth, Michael P.

    1989-01-01

    A variety of structural analyses have been performed on the Solid Rocket Boosters (SRB's) to provide information that would contribute to the understanding of the failure which destroyed the Space Shuttle Challenger. This paper describes nonlinear shell analyses that were performed to characterize the behavior of an overall SRB structure and a segment of the SRB in the vicinity of the External Tank Attachment (ETA) ring. Shell finite element models were used that would accurately reflect the global load transfer in an SRB in a manner such that nonlinear shell collapse and ovalization could be assessed. The purpose of these analyses was to calculate the overall deflection and stress distributions for these SRB models when subjected to mechanical loads corresponding to critical times during the launch sequence. Static analyses of these SRB models were performed using a snapshot picture of the loads. Analytical results obtained using these models show no evidence of nonlinear shell collapse for the pre-liftoff loading cases considered.

  2. A novel versatile multilayer hybrid stress solid-shell element

    NASA Astrophysics Data System (ADS)

    Rah, K.; Van Paepegem, W.; Degrieck, J.

    2013-06-01

    This paper presents a versatile multilayer locking free hybrid stress solid-shell element that can be readily employed for a wide range of geometrically linear elastic structural analyses, i.e. from shell-like isotropic structures to multilayer anisotropic composites. This solid-shell element has eight nodes with only displacement degrees of freedom and a few internal parameters that provide the locking free behavior and accurate interlaminar stress resolution through the element thickness. These elements can be stacked on top of each other to model multilayer structures, fulfilling the interlaminar stress continuity at the interlayer surfaces and zero traction conditions on the top and bottom surfaces of composite laminates. The element formulation is based on the modified form of the well-known Fraeijs de Veubeke-Hu-Washizu (FHW) multifield variational principle with enhanced assumed strains (EAS formulation) and assumed natural strains (ANS formulation) to alleviate the different types of locking phenomena in solid-shell elements. The distinct feature of the present formulation is its ability to accurately calculate the interlaminar stress field in multilayer structures, which is achieved by incorporating an assumed stress field in a standard EAS formulation based on the FHW principle. To assess the present formulation's accuracy, a variety of popular numerical benchmark examples related to element patch tests, convergence, mesh distortion, shell and laminated composite analyses are investigated and the results are compared with those available in the literature. This assessment reveals that the proposed solid-shell formulation provides very accurate results for a wide range of structural analyses.

  3. The free vibration of plates, shallow shells and solids

    NASA Astrophysics Data System (ADS)

    Young, Philippe Georges

    1993-07-01

    The Ritz approach is used to study the free structural vibration problem of a wide class of plates, shallow shells, and solids. The boundaries and/or internal supports of the systems are considered and described by polynomials in Cartesian coordinates. The geometric boundary conditions at these boundaries or supports are enforced by including in a simple polynomial trial series the polynomial equation describing the position of the support raised to the appropriate power. For plates and shallow shells, in some instances, the displacement field is discretized into several domains or elements, and continuity conditions along the connecting boundaries are enforced using a penalty method approach. Complicating effects such as point masses, stepped geometry, cutouts, and internal point supports are also considered. The natural frequencies and mode shapes of isotropic rectangular plates are obtained, then isotropic and orthotropic plates of more general form are considered. The approach is extended to shallow shells of differing shapes and curvatures, as well as complicating effects. The approach is finally applied to studying free vibration of a class of solids including a sphere, cylinders, a cone, and a prismatic solid of more general cross-section.

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

    PubMed

    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.

  5. Torrefaction of almond shells: effects of torrefaction conditions on properties of solid and condensate products

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Almond shells were torrefied in a fixed bed reactor and their solid and condensate products were collected for analysis. A central composite design and response surface methodology were used to examine effects of torrefaction temperature and time on mass and energy yields of solid products as well a...

  6. An 8-node tetrahedral finite element suitable for explicit transient dynamic simulations

    SciTech Connect

    Key, S.W.; Heinstein, M.W.; Stone, C.M.

    1997-12-31

    Considerable effort has been expended in perfecting the algorithmic properties of 8-node hexahedral finite elements. Today the element is well understood and performs exceptionally well when used in modeling three-dimensional explicit transient dynamic events. However, the automatic generation of all-hexahedral meshes remains an elusive achievement. The alternative of automatic generation for all-tetrahedral finite element is a notoriously poor performer, and the 10-node quadratic tetrahedral finite element while a better performer numerically is computationally expensive. To use the all-tetrahedral mesh generation extant today, the authors have explored the creation of a quality 8-node tetrahedral finite element (a four-node tetrahedral finite element enriched with four midface nodal points). The derivation of the element`s gradient operator, studies in obtaining a suitable mass lumping and the element`s performance in applications are presented. In particular, they examine the 80node tetrahedral finite element`s behavior in longitudinal plane wave propagation, in transverse cylindrical wave propagation, and in simulating Taylor bar impacts. The element only samples constant strain states and, therefore, has 12 hourglass modes. In this regard, it bears similarities to the 8-node, mean-quadrature hexahedral finite element. Given automatic all-tetrahedral meshing, the 8-node, constant-strain tetrahedral finite element is a suitable replacement for the 8-node hexahedral finite element and handbuilt meshes.

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

    PubMed

    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. PMID:26948023

  8. A solid-shell Cosserat point element ( SSCPE) for elastic thin structures at finite deformation

    NASA Astrophysics Data System (ADS)

    Jabareen, Mahmood; Mtanes, Eli

    2016-07-01

    The objective of this study is to develop a new solid-shell element using the Cosserat point theory for modeling thin elastic structures at finite deformations. The point-wise Green-Lagrange strain tensor is additively decomposed into homogeneous and inhomogeneous parts. Only the latter part of the strain tensor is modified by the assumed natural strain ANS concept to avoid both curvature-thickness locking and transverse shear locking. To the authors' knowledge, such modification has not been applied yet in the literature, and here it is referred to as the assumed natural inhomogeneous strain ANIS concept. Moreover, a new methodology for determining the constitutive coefficients of the strain energy function, which controls the inhomogeneous deformations, is proposed. The resulting coefficients ensure both accuracy, robustness, and elimination of all locking pathologies in the solid-shell Cosserat point element ( SSCPE). The performance of the developed SSCPE is verified and tested via various benchmark problems and compared to other solid, shell, and solid-shell elements. These examples demonstrate that the SSCPE is accurate, robust, stable, free of locking, and can be used for modeling thin structures at both small and finite deformations.

  9. Cloaking core-shell nanoparticles from conducting electrons in solids.

    PubMed

    Liao, Bolin; Zebarjadi, Mona; Esfarjani, Keivan; Chen, Gang

    2012-09-21

    In this Letter, we aim at making nanoparticles embedded in a host semiconductor with a size comparable to electronic wavelengths "invisible" to the electron transport. Inspired by the recent progress made in optics and working within the framework of the expansion of partial waves, we demonstrate that the opposite effects imposed by potential barriers and wells of a core-shell nanoparticle on the phase shifts associated with the scattered electron wave could make the scattering cross section of the first two partial waves vanish simultaneously. We show that this is sufficient to cloak the nanoparticle from being detected by electrons with specific energy in the sense that a total scattering cross section smaller than 0.01% of the physical cross section can be obtained and a 4 orders of magnitude difference in the total scattering cross section can be presented within an energy range of only 40 meV, indicating possible applications of the "electron cloaks" as novel electronic switches and sensors, and in efficient energy harvesting and conversion technologies. PMID:23005976

  10. Cloaking core-shell nanoparticles from conducting electrons in solids.

    PubMed

    Liao, Bolin; Zebarjadi, Mona; Esfarjani, Keivan; Chen, Gang

    2012-09-21

    In this Letter, we aim at making nanoparticles embedded in a host semiconductor with a size comparable to electronic wavelengths "invisible" to the electron transport. Inspired by the recent progress made in optics and working within the framework of the expansion of partial waves, we demonstrate that the opposite effects imposed by potential barriers and wells of a core-shell nanoparticle on the phase shifts associated with the scattered electron wave could make the scattering cross section of the first two partial waves vanish simultaneously. We show that this is sufficient to cloak the nanoparticle from being detected by electrons with specific energy in the sense that a total scattering cross section smaller than 0.01% of the physical cross section can be obtained and a 4 orders of magnitude difference in the total scattering cross section can be presented within an energy range of only 40 meV, indicating possible applications of the "electron cloaks" as novel electronic switches and sensors, and in efficient energy harvesting and conversion technologies.

  11. Polymer composite electrolytes having core-shell silica fillers with anion-trapping boron moiety in the shell layer for all-solid-state lithium-ion batteries.

    PubMed

    Shim, Jimin; Kim, Dong-Gyun; Kim, Hee Joong; Lee, Jin Hong; Lee, Jong-Chan

    2015-04-15

    Core-shell silica particles with ion-conducting poly(ethylene glycol) and anion-trapping boron moiety in the shell layer were prepared to be used as fillers for polymer composite electrolytes based on organic/inorganic hybrid branched copolymer as polymer matrix for all-solid-state lithium-ion battery applications. The core-shell silica particles were found to improve mechanical strength and thermal stability of the polymer matrix and poly(ethylene glycol) and boron moiety in the shell layer increase compatibility between filler and polymer matrix. Furthermore, boron moiety in the shell layer increases both ionic conductivity and lithium transference number of the polymer matrix because lithium salt can be more easily dissociated by the anion-trapping boron. Interfacial compatibility with lithium metal anode is also improved because well-dispersed silica particles serve as protective layer against interfacial side reactions. As a result, all-solid-state battery performance was found to be enhanced when the copolymer having core-shell silica particles with the boron moiety was used as solid polymer electrolyte.

  12. Template-Engaged Solid-State Synthesis of Barium Magnesium Silicate Yolk@Shell Particles and Their High Photoluminescence Efficiency.

    PubMed

    Chen, Xuncai; Kim, Woo-Sik

    2016-05-17

    This study presents a new synthetic method for fabricating yolk@shell-structured barium magnesium silicate (BMS) particles through a template-engaged solid-state reaction. First, as the core template, (BaMg)CO3 spherical particles were prepared based on the coprecipitation of Ba(2+) and Mg(2+) . These core particles were then uniformly shelled with silica (SiO2 ) by using CTAB as the structure-directing template to form (BaMg)CO3 @SiO2 particles with a core@shell structure. The (BaMg)CO3 @SiO2 particles were then converted to yolk@shell barium magnesium silicate (BMS) particles by an interfacial solid-state reaction between the (BaMg)CO3 (core) and the SiO2 (shell) at 750 °C. During this interfacial solid-state reaction, Kirkendall diffusion contributed to the formation of yolk@shell BMS particles. Thus, the synthetic temperature for the (BaMg)SiO4 :Eu(3+) phosphor is significantly reduced from 1200 °C with the conventional method to 750 °C with the proposed method. In addition, the photoluminescence intensity of the yolk@shell (BaMg)SiO4 :Eu(3+) phosphor was found to be 9.8 times higher than that of the conventional (BaMg)SiO4 :Eu(3+) phosphor. The higher absorption of excitation light by the structure of the yolk@shell phosphor is induced by multiple light-reflection and -scattering events in the interstitial void between the yolk and the shell. When preparing the yolk@shell (BaMg)SiO4 :Eu(3+) phosphor, a hydrogen environment for the solid-state reaction results in higher photoluminescence efficiency than nitrogen and air environments. The proposed synthetic method can be easily extended to the synthesis of other yolk@shell multicomponent metal silicates.

  13. Facile synthesis and microwave absorbability of C@Ni–NiO core–shell hybrid solid sphere and multi-shelled NiO hollow sphere

    SciTech Connect

    Wu, Hongjing; Wu, Guanglei; Wu, Qiaofeng; Wang, Liuding

    2014-11-15

    We reported the preparation of C@Ni–NiO core–shell hybrid solid spheres or multi-shelled NiO hollow spheres by combining a facile hydrothermal route with a calcination process in H{sub 2} or air atmosphere, respectively. The synthesized C@Ni–NiO core–shell solid spheres with diameters of approximately 2–6 μm were in fact built from dense NiO nanoparticles coated by random two-dimensional metal Ni nanosheets without any visible pores. The multi-shelled NiO hollow spheres were built from particle-like ligaments and there are a lot of pores with size of several nanometers on the surface. Combined Raman spectra with X-ray photoelectron spectra (XPS), it suggested that the defects in the samples play a limited role in the dielectric loss. Compared with the other samples, the permeability of the samples calcined in H{sub 2} and air was increased slightly and the natural resonance frequency shifted to higher frequency (7, 11 and 14 GHz, respectively), leading to an enhancement of microwave absorption property. For the sample calcined in H{sub 2}, an optimal reflection loss less than − 10 was obtained at 7 GHz with a matching thickness of 5.0 mm. Our study demonstrated the potential application of C@Ni–NiO core–shell hybrid solid sphere or multi-shelled NiO hollow sphere as a more efficient electromagnetic (EM) wave absorber. - Highlights: • C@Ni–NiO core–shell hybrid solid sphere was synthesized by a facile method. • Multi-shelled NiO hollow sphere was synthesized by a facile method. • It suggested that the defects in the samples play a limited role in dielectric loss. • The permeability of the samples calcined in H{sub 2} and air was increased. • Microwave absorbability of C@Ni–NiO core–shell hybrid solid sphere was investigated.

  14. A nonlinear solid shell element formulation for analysis of composite panels under blast wave pressure loading

    NASA Astrophysics Data System (ADS)

    Park, Hun

    A comprehensive methodology to accurately predict the dynamic response of composite panels under blast wave pressure loading has been successfully developed for the first time. It includes the modeling of geometrically nonlinear dynamic effect, progressive failure and strain-rate effect on constitutive equation and strength. For dynamic analysis, a nonlinear solid shell element formulation is combined with the trapezoidal rule for numerical integration in time. The progressive damage incorporates the effect of the material failure, such as fiber failure, matrix cracking and fiber-matrix shearing failure on the stiffness and strength. Material degradation models based on the rule of mixtures are proposed for each failure mode. To implement the strain-rate effect on the constitutive equation of the material, a viscoplastic model is adopted. In this model, three material parameters are determined by conducting uniaxial tension tests on off-axis specimen. The effect of strain rates on material strength is implemented via the linear least square fit of the test data. A key ingredient of the analysis is a geometrically nonlinear solid shell element based on the assumed strain formulation to alleviate element locking. In this approach, the composite shell is treated as a three-dimensional solid. Accordingly, the change of shell thickness is allowed and the kinematics of deformation is described by six vector components at a point on the shell midsurface. The mass matrix always remains constant during the analysis. Example problems under static and dynamic loadings are solved to investigate the behavior of composite panels undergoing large deformation while experiencing material damage. The analysis results are compared with the test data available. Results of the numerical analysis show that the effect of the progressive failure and strain-rates on structural responses are considerable. For a composite plate under static pressure loadings, maximum displacement and

  15. Preliminary 2-D shell analysis of the space shuttle solid rocket boosters

    NASA Technical Reports Server (NTRS)

    Knight, Norman F., Jr.; Gillian, Ronnie E.; Nemeth, Michael P.

    1987-01-01

    A two-dimensional shell model of an entire solid rocket booster (SRB) has been developed using the STAGSC-1 computer code and executed on the Ames CRAY computer. The purpose of these analyses is to calculate the overall deflection and stress distributions for the SRB when subjected to mechanical loads corresponding to critical times during the launch sequence. The mechanical loading conditions for the full SRB arise from the external tank (ET) attachment points, the solid rocket motor (SRM) pressure load, and the SRB hold down posts. The ET strut loads vary with time after the Space Shuttle main engine (SSME) ignition. The SRM internal pressure varies axially by approximately 100 psi. Static analyses of the full SRB are performed using a snapshot picture of the loads. The field and factory joints are modeled by using equivalent stiffness joints instead of detailed models of the joint. As such, local joint behavior cannot be obtained from this global model.

  16. Axisymmetric shell analysis of the space shuttle solid rocket booster field joint

    NASA Technical Reports Server (NTRS)

    Nemeth, Michael P.; Anderson, Melvin S.

    1991-01-01

    The Space Shuttle Challenger (STS 51-L) accident led to an intense investigation of the structural behavior of the solid rocket booster (SRB) tang and clevis field joints. Results are presented of axisymmetric shell analyses that parametrically assess the structural behavior of SRB field joints subjected to quasi-steady-state internal pressure loading for both the original joint flown on mission STS 51-L and the redesigned joint flown for the first time after the STS 51-L accident on the Space Shuttle Discovery. Discussion of axisymmetric shell modeling issues and details is presented and a generic method for simulating contact between adjacent shells of revolution is described. Results are presented that identify the performance trends of the joints for a wide range of joint parameters. An important finding is that the redesigned joint exhibits significantly smaller O-ring gap changes and much less sensitivity to joint clearances than the original joint. For a wide range of joint parameters, the result presented indicate that the redesigned joint provides a much better pressure seal than the original joint.

  17. Evaluation of Flygt Propeller Xixers for Double Shell Tank (DST) High Level Waste Auxiliary Solids Mobilization

    SciTech Connect

    PACQUET, E.A.

    2000-07-20

    The River Protection Project (RPP) is planning to retrieve radioactive waste from the single-shell tanks (SST) and double-shell tanks (DST) underground at the Hanford Site. This waste will then be transferred to a waste treatment plant to be immobilized (vitrified) in a stable glass form. Over the years, the waste solids in many of the tanks have settled to form a layer of sludge at the bottom. The thickness of the sludge layer varies from tank to tank, from no sludge or a few inches of sludge to about 15 ft of sludge. The purpose of this technology and engineering case study is to evaluate the Flygt{trademark} submersible propeller mixer as a potential technology for auxiliary mobilization of DST HLW solids. Considering the usage and development to date by other sites in the development of this technology, this study also has the objective of expanding the knowledge base of the Flygt{trademark} mixer concept with the broader perspective of Hanford Site tank waste retrieval. More specifically, the objectives of this study delineated from the work plan are described.

  18. Shell and solid modeling for structural body-in-white part

    NASA Astrophysics Data System (ADS)

    Senin, Azman; Nopiah, Zulkifli Mohd; Jamaludin, Muhammad Jamhuri; Abidin, Mohd Azmir; Zaudin, Muhamad Azuan; Ahmad, Muhammad Afzal; Zakaria, Ahmad

    2013-12-01

    Finite-Element Analysis (FEA) is a numerical method that facilitates designers to produce a part with the high degree of reliability. These advantages allow manufacturing engineer to produce a virtual tool prototype. This approach has eliminated the requirement to manufacture the prototype model from soft tool parts and soft tool press die. This research focuses on the numerical experiments for an advanced high-strength steel part in Body-in-White. The patchwork blank sheet of a structural body in white is modeled with three conditions - shell elements without spot welding nuggets, Shell elements with spot welding nuggets and Solid elements. Shell elements are usually the obvious choice in the blank in sheet metal forming simulation primarily due to the rapid and fairly accurate results generated. Solid elements of the other hand require extremely high computation time. The main objective of this study is to critically compare plastic deformation results obtained from three approaches on a B-Pillar part with 1.75mm thickness. The finite-element models are developed from the CAD data of production tool and blank material. The blank material is meshed with quad elements for optimized computing time and results. The input parameters for the simulation models are obtained from the current setup at Press Machine and Production Tool. The analyses of plastic deformation for all three blank material models are compared to the actual part thickness. Percentage of deviation from the actual part geometry will indicate the best approach in producing finite-element models for Hot forming process.

  19. Core-shell electrospun polybutylene terephthalate/polypyrrole hollow nanofibers for micro-solid phase extraction.

    PubMed

    Bagheri, Habib; Rezvani, Omid; Banihashemi, Solmaz

    2016-02-19

    In the present work, a new micro-solid phase extraction (μ-SPE) sorbent as an extracting medium based on core-shell nanofibers was synthesized by electrospinning. The core-shell nanofibers of polyvinylpyrrolidone-Polybutylene terephthalate/polypyrrole (PVP-PBT/PPy) were electrospun and subsequently, modified hollow nanofibers were prepared by removing the central PVP moiety. Moreover, conventional PBT/PPy was also prepared for the comparison purposes. The homogeneity and the porous surface structure of the core-shell nanofibers were confirmed by scanning electron microscopy (SEM). The applicability of the fabricated nanofibers-coating was examined by immersed μ-SPE of some selected triazine herbicides from aqueous samples and wheat grains. Subsequently, the extracted analytes were transferred into a gas chromatography (GC) after solvent desorption. Influencing parameters on the morphology of nanofiber such as elctrospinning parameters and the weight ratio of components were optimized. In addition, effects of different parameters influencing the extraction efficiency including extraction temperature, extraction time, ionic strength, sample pH, desorption temperature, and desorption time were investigated and optimized. Eventually, the developed method was validated by gas chromatography-mass spectrometry (GC-MS). At the optimum conditions, the relative standard deviation values for real water samples spiked with the selected triazines at 1 ng mL(-1) were 4-8% (n=3) and the limits of detection for the studied compounds were between 50 and 90 ng L(-1). The calibration curves for the selected triazines were in the range of 0.3-500 ng mL(-1) and regression coefficients (R(2)) were between 0.9985 and 0.9996. PMID:26810808

  20. Characterizing Solids in Residual Wastes from Single-Shell Tanks at the Hanford Site.

    SciTech Connect

    Krupka, Kenneth M.; Cantrell, Kirk J.; Schaef, Herbert T.; Arey, Bruce W.; Heald, Steve M.; Deutsch, William J.; Lindberg, Michael J.

    2010-03-03

    Solid-phase characterization methods have been used in an ongoing study of residual wastes (i.e., waste remaining after final retrieval operations) from underground single-shell storage tanks 241-C-103, 241 C 106, 241-C-202, 241-C-203, and 241-S-112 at the U.S. Department of Energy’s Hanford Site in Washington State. The results of studies completed to date show variability in the compositions of those residual wastes and the compositions, morphologies, and crystallinities of the individual phases that make up these wastes. These differences undoubtedly result from the various waste types stored and transferred into and out of each tank and the different sluicing and retrieval operations used for waste retrieval. The studies indicate that these residual wastes are chemically-complex assemblages of crystalline and amorphous solids that contain contaminants as discrete phases and/or coprecipitated within oxide/hydroxide phases. Depending on the specific tank, various solids (e.g., gibbsite; böhmite; dawsonite; cancrinite; Fe oxides/hydroxides such as hematite, goethite, and maghemite; rhodochrosite; lindbergite; whewellite; nitratine; and numerous amorphous or poorly crystalline phases) have been identified by X-ray diffraction and scanning electron microscopy/energy dispersive X-ray spectroscopy in residual wastes studied to date. The studies also show that contact of residual wastes with Ca(OH)2- and CaCO3-saturated aqueous solutions, which were used as surrogates for the compositions of pore-fluid leachants derived from young and aged cements, respectively, may alter the composition of solid phases present in the contacted wastes. Iron oxides/hydroxides have been identified in all residual wastes studied to date. They occur in these wastes as discrete particles, particles intergrown within a matrix of other phases, and surface coatings on other particles or particle aggregates. These Fe oxides/hydroxides typically contain trace concentrations of other

  1. An assessment of finite-element modeling techniques for thick-solid/thin-shell joints analysis

    NASA Technical Reports Server (NTRS)

    Min, J. B.; Androlake, S. G.

    1993-01-01

    The subject of finite-element modeling has long been of critical importance to the practicing designer/analyst who is often faced with obtaining an accurate and cost-effective structural analysis of a particular design. Typically, these two goals are in conflict. The purpose is to discuss the topic of finite-element modeling for solid/shell connections (joints) which are significant for the practicing modeler. Several approaches are currently in use, but frequently various assumptions restrict their use. Such techniques currently used in practical applications were tested, especially to see which technique is the most ideally suited for the computer aided design (CAD) environment. Some basic thoughts regarding each technique are also discussed. As a consequence, some suggestions based on the results are given to lead reliable results in geometrically complex joints where the deformation and stress behavior are complicated.

  2. Frequency Split Elimination Method for a Solid-State Vibratory Angular Rate Gyro with an Imperfect Axisymmetric-Shell Resonator

    PubMed Central

    Lin, Zhen; Fu, Mengyin; Deng, Zhihong; Liu, Ning; Liu, Hong

    2015-01-01

    The resonator of a solid-state vibratory gyro is responsible for sensing angular motion. Frequency splitting of an axisymmetric-shell resonator is a common problem caused by manufacturing defects. The defect causes a frequency difference between two working modes which consist of two nodes and two antinodes. The difference leads to the loss of gyroscopic effect, and thus the resonator cannot sense angular motion. In this paper, the resonator based on an axisymmetric multi-curved surface shell structure is investigated and an approach to eliminate frequency splits is proposed. Since axisymmetric multi-curved surface shell resonators are too complex to be modeled, this paper proposes a simplified model by focusing on a common property of the axisymmetric shell. The resonator with stochastic imperfections is made equivalent to a perfect shell with an imperfect mass point. Rayleigh's energy method is used in the theoretical analysis. Finite element modeling is used to demonstrate the effectiveness of the elimination approach. In real cases, a resonator's frequency split is eliminated by the proposed approach. In this paper, errors in the theoretical analysis are discussed and steps to be taken when the deviation between assumptions and the real situation is large are figured out. The resonator has good performance after processing. The elimination approach can be applied to any kind of solid-state vibratory gyro resonators with an axisymmetric shell structure. PMID:25648707

  3. Geological evidence for solid-state convection in Europa's ice shell.

    PubMed

    Pappalardo, R T; Head, J W; Greeley, R; Sullivan, R J; Pilcher, C; Schubert, G; Moore, W B; Carr, M H; Moore, J M; Belton, M J; Goldsby, D L

    1998-01-22

    The ice-rich surface of the jovian satellite Europa is sparsely cratered, suggesting that this moon might be geologically active today. Moreover, models of the satellite's interior indicate that tidal interactions with Jupiter might produce enough heat to maintain a subsurface liquid water layer. But the mechanisms of interior heat loss and resurfacing are currently unclear, as is the question of whether Europa has (or had at one time) a liquid water ocean. Here we report on the morphology and geological interpretation of distinct surface features-pits, domes and spots-discovered in high-resolution images of Europa obtained by the Galileo spacecraft. The features are interpreted as the surface manifestation of diapirs, relatively warm localized ice masses that have risen buoyantly through the subsurface. We find that the formation of the features can be explained by thermally induced solid-state convection within an ice shell, possibly overlying a liquid water layer. Our results are consistent with the possibility that Europa has a liquid water ocean beneath a surface layer of ice, but further tests and observations are needed to demonstrate this conclusively. PMID:9450750

  4. Disks solid phase extraction based polypyrrole functionalized core-shell nanofibers mat.

    PubMed

    Qi, FeiFei; Li, XiaoQing; Yang, BiYi; Rong, Fei; Xu, Qian

    2015-11-01

    A novel disks solid phase extraction (SPE) based on polypyrrole (PPy) functionalized core-shell electrospun nanofibers mat was proposed. The performance of the established disks SPE technique was evaluated in the extraction of trace polar analytes from environmental water samples. Disulphonated (acid yellow 9) and monosulphonated azo dyes (acid orange 7 and metanil yellow) were selected as typical model analytes. Under the optimum conditions, detection limits were 0.15-0.3 μg/L for all target analytes and the enrichment coefficients were 106-121. The recoveries of sulfonated azo dyes added to typical environmental water samples were 87.6-112.3%, suggesting that the interferences of the sample matrix did not affect the enrichment. Compared with existing methods, the device in this study showed higher recovery, lower detection limit and better precision. Moreover, the miniaturized disks SPE technique for sample preparation is simple and fast, with significantly reduced sorbent bed mass (2.5 mg) and eluent volume (500 μL). These results indicate that PPy nanofibers mat-based disks SPE may be a promising device that can effectively extract the polar species in water samples. PMID:26452802

  5. Geological evidence for solid-state convection in Europa's ice shell

    USGS Publications Warehouse

    Pappalardo, R.T.; Head, J.W.; Greeley, R.; Sullivan, R.J.; Pilcher, C.; Schubert, G.; Moore, W.B.; Carr, M.H.; Moore, Johnnie N.; Belton, M.J.S.; Goldsby, D.L.

    1998-01-01

    The ice-rich surface of the jovian satellite Europa is sparsely cratered, suggesting that this moon might be geologically active today. Moreover, models of the satellite's interior indicate that tidal interactions with Jupiter might produce enough heat to maintain a subsurface liquid water layer. But the mechanisms of interior heat loss and resurfacing are currently unclear, as is the question of whether Europa has (or had at one time) a liquid water ocean. Here we report on the morphology and geological interpretation of distinct surface features-pits, domes and spots-discovered in high-resolution images of Europa obtained by the Galileo spacecraft. The features are interpreted as the surface manifestation of diapirs, relatively warm localized ice masses that have risen buoyantly through the subsurface. We find that the formation of the features can be explained by thermally induced solid-state convection within an ice shell, possibly overlying a liquid water layer. Our results are consistent with the possibility that Europa has a liquid water ocean beneath a surface layer of ice, but further tests and observations are needed to demonstrate this conclusively.

  6. Core-Shell Diamond as a Support for Solid-Phase Extraction and High-Performance Liquid Chromatography

    SciTech Connect

    Saini, Gaurav; Jensen, David S.; Wiest, Landon A.; Vail, Michael A.; Dadson, Andrew; Lee, Milton L.; Shutthanandan, V.; Linford, Matthew R.

    2010-06-01

    We report the formation of core-shell diamond particles for solid phase extraction (SPE) and high performance liquid chromatography (HPLC) made by layer-by-layer (LbL) deposition. Their synthesis begins with the amine functionalization of microdiamond by its immersion in an aqueous solution of a primary amine-containing polymer (polyallylamine (PAAm)). The amine-terminated microdiamond is then immersed in an aqueous suspension of nanodiamond, which leads to adsorption of the nanodiamond. Alternating (self-limiting) immersions in the solutions of the amine-containing polymer and the suspension of nanodiamond are continued until the desired number of nanodiamond layers is formed around the microdiamond. Finally, the core-shell particles are cross-linked with 1,2,5,6-diepoxycyclooctane or reacted with 1,2-epoxyoctadecane. Layer-by-layer deposition of PAAm and nanodiamond is also studied on planar Si/SiO2 surfaces, which were characterized by SEM, Rutherford backscattering spectrometry (RBS) and nuclear reaction analysis (NRA). Core-shell particles are characterized by diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), environmental scanning electron microscopy (ESEM), and Brunauer Emmett Teller (BET) surface area and pore size measurements. Larger (ca. 50 μm) core-shell diamond particles have much higher surface areas, and analyte loading capacities in SPE than nonporous solid diamond particles. Smaller (ca. 3 μm), normal and reversed phase, core-shell diamond particles have been used for HPLC, with 36,300 plates per meter for mesitylene in a separation of benzene and alkyl benzenes on a C18 adsorbent, and 54,800 plates per meter for diazinon in a similar separation of two pesticides.

  7. A facile route to core-shell nanoparticulate formation of arsenic trioxide for effective solid tumor treatment

    NASA Astrophysics Data System (ADS)

    Zhang, Zongjun; Liu, Hanyu; Zhou, Hualu; Zhu, Xianglong; Zhao, Zhenghuan; Chi, Xiaoqin; Shan, Hong; Gao, Jinhao

    2016-02-01

    Arsenic trioxide has achieved great clinical success in the treatment of acute promyelocytic leukemia (APL). However, it is difficult to replicate the success in other cancers, such as solid tumors, in part because of the rapid renal clearance and dose-limiting toxicity. Nanotechnology is expected to overcome these disadvantages through altering its pharmacokinetics and concentrating the drug at the desired sites. Herein, we report a ``one-pot'' method to develop arsenic-based nanodrugs by in situ coating the as-prepared arsenic nanocomplexes with porous silica shells. This process can be easily reproduced and scaled up because no complicated synthesis and purification steps are involved. This core-shell embedding method endows nanodrugs with high loading capacity (57.9 wt%) and a prolonged pH-responsive releasing profile, which is crucial to increase the drug concentration at tumor sites and improve the drug efficacy. Based on these unique features, the nanodrugs significantly inhibit the growth of solid tumors without adverse side effects. Therefore, we anticipate that the arsenic-based nanodrugs generated by this facile synthetic route may be a powerful and alternative strategy for solid tumor therapy.Arsenic trioxide has achieved great clinical success in the treatment of acute promyelocytic leukemia (APL). However, it is difficult to replicate the success in other cancers, such as solid tumors, in part because of the rapid renal clearance and dose-limiting toxicity. Nanotechnology is expected to overcome these disadvantages through altering its pharmacokinetics and concentrating the drug at the desired sites. Herein, we report a ``one-pot'' method to develop arsenic-based nanodrugs by in situ coating the as-prepared arsenic nanocomplexes with porous silica shells. This process can be easily reproduced and scaled up because no complicated synthesis and purification steps are involved. This core-shell embedding method endows nanodrugs with high loading capacity

  8. Core-shell microcapsules of solid lipid nanoparticles and mesoporous silica for enhanced oral delivery of curcumin.

    PubMed

    Kim, Sanghoon; Diab, Roudayna; Joubert, Olivier; Canilho, Nadia; Pasc, Andreea

    2016-04-01

    Newly designed microcapsules (MC) combining a core of solid lipid nanoparticle (SLN) and a mesoporous silica shell have been developed and explored as oral delivery system of curcumin (CU). CU-loaded MC (MC-CU) are 2 μm sized and have a mesoporous silica shell of 0.3 μm thickness with a wormlike structure as characterized by small angle X-ray scattering (SAXS), nitrogen adsorption/desorption and transmission electron microscopy (TEM) measurements. It was found that SLN acts as reservoir of curcumin while the mesoporous shell insures the protection and the controlled release of the drug. MC-CU displayed a pH-dependent in vitro release profile with marked drug retention at pH 2.8. Neutral red uptake assay together with confocal laser scanning microscopy (CLSM) showed a good cell tolerance to MC-CU at relatively high concentration of inert materials. Besides, the cell-uptake test revealed that fluorescent-MC were well internalized into Caco-2 cells, confirming the possibility to use MC for gut cells targeting. These findings suggest that organic core-silica shell microcapsules are promising drug delivery systems with enhanced bioavailability for poorly soluble drugs. PMID:26752213

  9. Electrosprayed core–shell solid dispersions of acyclovir fabricated using an epoxy-coated concentric spray head

    PubMed Central

    Liu, Zhe-Peng; Cui, Lei; Yu, Deng-Guang; Zhao, Zhuan-Xia; Chen, Lan

    2014-01-01

    A novel structural solid dispersion (SD) taking the form of core–shell microparticles for poorly water-soluble drugs is reported for the first time. Using polyvinylpyrrolidone (PVP) as a hydrophilic polymer matrix, the SDs were fabricated using coaxial electrospraying (characterized by an epoxy-coated concentric spray head), although the core fluids were unprocessable using one-fluid electrospraying. Through manipulating the flow rates of the core drug-loaded solutions, two types of core–shell microparticles with tunable drug contents were prepared. They had average diameters of 1.36±0.67 and 1.74±0.58 μm, and were essentially a combination of nanocomposites with the active ingredient acyclovir (ACY) distributed in the inner core, and the sweeter sucralose and transmembrane enhancer sodium dodecyl sulfate localized in the outer shell. Differential scanning calorimetry and X-ray diffraction results demonstrated that ACY, sodium dodecyl sulfate, and sucralose were well distributed in the PVP matrix in an amorphous state because of favorable second-order interactions. In vitro dissolution and permeation studies showed that the core–shell microparticle SDs rapidly freed ACY within 1 minute and promoted nearly eightfold increases in permeation rate across the sublingual mucosa compared with raw ACY powders. PMID:24790437

  10. Characterization of solids in residual wastes from single-shell tanks at the Hanford site, Washington, USA.

    SciTech Connect

    Krupka, K. M.; Cantrell, K. J.; Todd Schaef, H.; Arey, B. W.; Heald, S. M.; Deutsch, W. J.; Lindberg, M. J.

    2010-03-01

    Solid phase physical and chemical characterization methods have been used in an ongoing study of residual wastes from several single-shell underground waste tanks at the U.S. Department of Energy's Hanford Site in southeastern Washington State. Because these wastes are highly-radioactive dispersible powders and are chemically-complex assemblages of crystalline and amorphous solids that contain contaminants as discrete phases and/or co-precipitated within oxide phases, their detailed characterization offers an extraordinary technical challenge. X-ray diffraction (XRD) and scanning electron microscopy/energy dispersive x-ray spectroscopy (SEM/EDS) are the two principal methods used, along with a limited series of analyses by synchrotron-based methods, to characterize solid phases and their contaminant associations in these wastes.

  11. A facile route to core-shell nanoparticulate formation of arsenic trioxide for effective solid tumor treatment.

    PubMed

    Zhang, Zongjun; Liu, Hanyu; Zhou, Hualu; Zhu, Xianglong; Zhao, Zhenghuan; Chi, Xiaoqin; Shan, Hong; Gao, Jinhao

    2016-02-21

    Arsenic trioxide has achieved great clinical success in the treatment of acute promyelocytic leukemia (APL). However, it is difficult to replicate the success in other cancers, such as solid tumors, in part because of the rapid renal clearance and dose-limiting toxicity. Nanotechnology is expected to overcome these disadvantages through altering its pharmacokinetics and concentrating the drug at the desired sites. Herein, we report a "one-pot" method to develop arsenic-based nanodrugs by in situ coating the as-prepared arsenic nanocomplexes with porous silica shells. This process can be easily reproduced and scaled up because no complicated synthesis and purification steps are involved. This core-shell embedding method endows nanodrugs with high loading capacity (57.9 wt%) and a prolonged pH-responsive releasing profile, which is crucial to increase the drug concentration at tumor sites and improve the drug efficacy. Based on these unique features, the nanodrugs significantly inhibit the growth of solid tumors without adverse side effects. Therefore, we anticipate that the arsenic-based nanodrugs generated by this facile synthetic route may be a powerful and alternative strategy for solid tumor therapy.

  12. Cu3Si@Si core-shell nanoparticles synthesized using a solid-state reaction and their performance as anode materials for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Zhou, Jianbin; Lin, Ning; Han, Ying; Zhou, Jie; Zhu, Yongchun; Du, Jin; Qian, Yitai

    2015-09-01

    Cu3Si@Si core-shell nanoparticles with a Si shell coated over the Cu3Si core are synthesized by a solid-state reaction between CuCl and Si. The evaluation process of the core-shell structure shows a mechanism analogous to the Kirkendall effect. As anode materials for lithium ion batteries, Cu3Si@Si core-shell nanoparticles retained a capacity of 903.6 mA h g-1 at the current density of 2 A g-1 over 400 cycles.Cu3Si@Si core-shell nanoparticles with a Si shell coated over the Cu3Si core are synthesized by a solid-state reaction between CuCl and Si. The evaluation process of the core-shell structure shows a mechanism analogous to the Kirkendall effect. As anode materials for lithium ion batteries, Cu3Si@Si core-shell nanoparticles retained a capacity of 903.6 mA h g-1 at the current density of 2 A g-1 over 400 cycles. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr04456a

  13. Tailoring surface plasmon resonance and dipole cavity plasmon modes of scattering cross section spectra on the single solid-gold/gold-shell nanorod

    NASA Astrophysics Data System (ADS)

    Chou Chau, Yuan-Fong; Lim, Chee Ming; Lee, Chuanyo; Huang, Hung Ji; Lin, Chun-Ting; Kumara, N. T. R. N.; Yoong, Voo Nyuk; Chiang, Hai-Pang

    2016-09-01

    Tunable surface plasmon resonance (SPR) and dipole cavity plasmon modes of the scattering cross section (SCS) spectra on the single solid-gold/gold-shell nanorod have been numerically investigated by using the finite element method. Various effects, such as the influence of SCS spectra under x- and y-polarizations on the surface of the single solid-gold/gold-shell nanorod, are discussed in detail. With the single gold-shell nanorod, one can independently tune the relative SCS spectrum width by controlling the rod length and rod diameter, and the surface scattering by varying the shell thickness and polarization direction, as well as the dipole peak energy. These behaviors are consistent with the properties of localized SPRs and offer a way to optically control and produce selected emission wavelengths from the single solid-gold/gold-shell nanorod. The electric field and magnetic distributions provide us a qualitative idea of the geometrical properties of the single solid-gold/gold-shell nanorod on plasmon resonance.

  14. Optimizing the electric field around solid and core-shell alloy nanostructures for near-field applications.

    PubMed

    Montaño-Priede, Luis; Peña-Rodríguez, Ovidio; Rivera, Antonio; Guerrero-Martínez, Andrés; Pal, Umapada

    2016-08-21

    The near electric field enhancement around plasmonic nanoparticles (NPs) is very important for applications like surface enhanced spectroscopies, plasmonic dye-sensitized solar cells and plasmon-enhanced OLEDs, where the interactions occur close to the surface of the NPs. In this work we have calculated the near-field enhancement around solid and core-shell alloy NPs as a function of their geometrical parameters and composition. We have found that the field enhancement is lower in the AuxAg1-x alloys with respect to pure Ag NPs, but it is still high enough for most near-field applications. The higher order modes have a stronger influence over the near-field due to a sharper spatial decay of the near electric field with the increase of the order of multipolar modes. For the same reason, in AuxAg1-x@SiO2 core-shell structures, the quadrupolar mode is dominant around the core, whereas the dipolar mode is predominant around the shell. The LSPR modes can have different behaviours in the near- and the far-field, particularly for larger particles with high Ag contents, which indicates that caution must be exercised for designing plasmonic nanostructures for near-field applications, as the variations of the LSPR in the near-field cannot be inferred from those observed in the far-field. These results have important implications for the application of gold-silver alloy NPs in surface enhanced spectroscopies and in the fabrication of plasmon-based optoelectronic devices, like dye-sensitized solar cells and plasmon-enhanced organic light-emitting diodes.

  15. Optimizing the electric field around solid and core-shell alloy nanostructures for near-field applications

    NASA Astrophysics Data System (ADS)

    Montaño-Priede, Luis; Peña-Rodríguez, Ovidio; Rivera, Antonio; Guerrero-Martínez, Andrés; Pal, Umapada

    2016-08-01

    The near electric field enhancement around plasmonic nanoparticles (NPs) is very important for applications like surface enhanced spectroscopies, plasmonic dye-sensitized solar cells and plasmon-enhanced OLEDs, where the interactions occur close to the surface of the NPs. In this work we have calculated the near-field enhancement around solid and core-shell alloy NPs as a function of their geometrical parameters and composition. We have found that the field enhancement is lower in the AuxAg1-x alloys with respect to pure Ag NPs, but it is still high enough for most near-field applications. The higher order modes have a stronger influence over the near-field due to a sharper spatial decay of the near electric field with the increase of the order of multipolar modes. For the same reason, in AuxAg1-x@SiO2 core-shell structures, the quadrupolar mode is dominant around the core, whereas the dipolar mode is predominant around the shell. The LSPR modes can have different behaviours in the near- and the far-field, particularly for larger particles with high Ag contents, which indicates that caution must be exercised for designing plasmonic nanostructures for near-field applications, as the variations of the LSPR in the near-field cannot be inferred from those observed in the far-field. These results have important implications for the application of gold-silver alloy NPs in surface enhanced spectroscopies and in the fabrication of plasmon-based optoelectronic devices, like dye-sensitized solar cells and plasmon-enhanced organic light-emitting diodes.

  16. Copper fine-structure K-shell electron impact ionization cross sections for fast-electron diagnostic in laser-solid experiments

    SciTech Connect

    Palmeri, P.; Quinet, P.; Batani, D.

    2015-03-15

    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, copper is a material that has been often used in those experiments because it has a maximum total K-shell emission yield. Furthermore, 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 copper isonuclear ions have been calculated. In this study, the K-shell EII cross sections connecting the ground and the metastable levels of the parent copper 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 10 times the K-shell threshold energies. Moreover, the resulting DW cross sections have been extrapolated at higher energies using the asymptotic form proposed by Davies et al. (2013)

  17. Effects and Mechanisms of Surface Topography on the Antiwear Properties of Molluscan Shells (Scapharca subcrenata) Using the Fluid-Solid Interaction Method

    PubMed Central

    Tian, Limei; Tian, Ximei; Hu, Guoliang; Wang, Yinci; Ren, Luquan

    2014-01-01

    The surface topography (surface morphology and structure) of the left Scapharca subcrenata shell differs from that of its right shell. This phenomenon is closely related to antiwear capabilities. The objective of this study is to investigate the effects and mechanisms of surface topography on the antiwear properties of Scapharca subcrenata shells. Two models are constructed—a rib morphology model (RMM) and a coupled structure model (CSM)—to mimic the topographies of the right and left shells. The antiwear performance and mechanisms of the two models are studied using the fluid-solid interaction (FSI) method. The simulation results show that the antiwear capabilities of the CSM are superior to those of the RMM. The CSM is also more conducive to decreasing the impact velocity and energy of abrasive particles, reducing the probability of microcrack generation, extension, and desquamation. It can be deduced that in the real-world environment, Scapharca subcrenata's left shell sustains more friction than its right shell. Thus, the coupled structure of the left shell is the result of extensive evolution. PMID:24982928

  18. L-shell emission from high-Z solid targets by intense (10{sup 19}W/cm{sup 2}) irradiation with a 248nm laser

    SciTech Connect

    Nelson, T. R.; Borisov, A. B.; Boyer, K.; Schroeder, W. A.; Santoro, J.; Van Tassle, A. J.; Rhodes, C. K.; Luk, T. S.; Cameron, S.; Longworth, J. W.; McPherson, A.

    1999-11-22

    Efficient (1.2% yield) multikilovolt x-ray emission from Ba(L) (2.4--2.8{angstrom}) and Gd(L) (1.7--2.1{angstrom}) is produced by ultraviolet (248nm) laser-excited BaF{sub 2} and Gd solids. The high efficiency is attributed to an inner shell-selective collisional electron ejection.

  19. Exact geometry solid-shell element based on a sampling surfaces technique for 3D stress analysis of doubly-curved composite shells

    NASA Astrophysics Data System (ADS)

    Kulikov, G. M.; Mamontov, A. A.; Plotnikova, S. V.; Mamontov, S. A.

    2015-11-01

    A hybrid-mixed ANS four-node shell element by using the sampling surfaces (SaS) technique is developed. The SaS formulation is based on choosing inside the nth layer In not equally spaced SaS parallel to the middle surface of the shell in order to introduce the displacements of these surfaces as basic shell variables. Such choice of unknowns with the consequent use of Lagrange polynomials of degree In - 1 in the thickness direction for each layer permits the presentation of the layered shell formulation in a very compact form. The SaS are located inside each layer at Chebyshev polynomial nodes that allows one to minimize uniformly the error due to the Lagrange interpolation. To implement the efficient analytical integration throughout the element, the enhanced ANS method is employed. The proposed hybrid-mixed four-node shell element is based on the Hu-Washizu variational equation and exhibits a superior performance in the case of coarse meshes. It could be useful for the 3D stress analysis of thick and thin doubly-curved shells since the SaS formulation gives the possibility to obtain numerical solutions with a prescribed accuracy, which asymptotically approach the exact solutions of elasticity as the number of SaS tends to infinity.

  20. Vanadium fine-structure K-shell electron impact ionization cross sections for fast-electron diagnostic in laser–solid experiments

    SciTech Connect

    Palmeri, P.; Quinet, P.; Batani, D.

    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)

  1. A nonlinear, implicit, three-dimensional finite element code for solid and structural mechanics - User`s Manual

    SciTech Connect

    Maker, B.N.

    1995-04-14

    This report provides a user`s manual for NIKE3D, a fully implicit three-dimensional finite element code for analyzing the finite strain static and dynamic response of inelastic solids, shells, and beams. Spatial discretization is achieved by the use of 8-node solid elements, 2-node truss and beam elements, and 4-node membrane and shell elements. Over twenty constitutive models are available for representing a wide range of elastic, plastic, viscous, and thermally dependent material behavior. Contact-impact algorithms permit gaps, frictional sliding, and mesh discontinuities along material interfaces. Several nonlinear solution strategies are available, including Full-, Modified-, and Quasi-Newton methods. The resulting system of simultaneous linear equations is either solved iteratively by an element-by-element method, or directly by a factorization method, for which case bandwidth minimization is optional. Data may be stored either in or out of core memory to allow for large analyses.

  2. On the Assumed Natural Strain method to alleviate locking in solid-shell NURBS-based finite elements

    NASA Astrophysics Data System (ADS)

    Caseiro, J. F.; Valente, R. A. F.; Reali, A.; Kiendl, J.; Auricchio, F.; Alves de Sousa, R. J.

    2014-06-01

    In isogeometric analysis (IGA), the functions used to describe the CAD geometry (such as NURBS) are also employed, in an isoparametric fashion, for the approximation of the unknown fields, leading to an exact geometry representation. Since the introduction of IGA, it has been shown that the high regularity properties of the employed functions lead in many cases to superior accuracy per degree of freedom with respect to standard FEM. However, as in Lagrangian elements, NURBS-based formulations can be negatively affected by the appearance of non-physical phenomena that "lock" the solution when constrained problems are considered. In order to alleviate such locking behaviors, the Assumed Natural Strain (ANS) method proposed for Lagrangian formulations is extended to NURBS-based elements in the present work, within the context of solid-shell formulations. The performance of the proposed methodology is assessed by means of a set of numerical examples. The results allow to conclude that the employment of the ANS method to quadratic NURBS-based elements successfully alleviates non-physical phenomena such as shear and membrane locking, significantly improving the element performance.

  3. Engineered core/shell quantum dots as phosphors for solid-state lighting

    SciTech Connect

    Klimov, Victor Ivanovich; Pietryga, Jeffrey Michael; McDaniel, Hunter

    2015-01-14

    Light-emitting diodes (LEDs) for solid state light ing (SSL) typically combine a blue or near- ultraviolet drive LED with one or more dow nconverting phosphors to produce “white” light. Further advances in both efficiency and wh ite-light quality will re quire new phosphors with narrow-band, highly efficient emission, particul arly in the red. A team led by principal investigator Dr. Victor Klim ov of Los Alamos National Labo ratory proposes to develop engineered semiconductor nanocrystal quantum dots (QDs) that combine optimal luminescent properties with long-term stability under ty pical downconverting conditions to enable new performance levels in SSL. The white LED phosphor industry is estimated to have sales of roughly $400 million in 2018 and would significantly benefit from the development of bright and narrow red-emitting QD phosphors because they woul d enable warmer whites without wasting energy by emission of light beyond the response of the human eye. In order to capitalize on the market opportunity, the LANL team is partnering with a local company called UbiQD that will facilitate US manufacturing.

  4. Air-Stable, Near- to Mid-Infrared Emitting Solids of PbTe/CdTe Core-Shell Colloidal quantum dots.

    PubMed

    Protesescu, Loredana; Zünd, Tanja; Bodnarchuk, Maryna I; Kovalenko, Maksym V

    2016-03-01

    Light emitters and detectors operating in the near- and mid-infrared spectral regions are important to many applications, such as telecommunications, high-resolution gas analysis, atmospheric pollution monitoring, medical diagnostics, and night vision. Various lead chalcogenides (binary, ternary, and quaternary alloys) in the form of quantum dots (QDs) or quantum wells provide narrow bandgap energies that cover the broad infrared region corresponding to wavelengths of 1-30 μm. Here, we report an inexpensive, all-solution-based synthesis strategy to thin-film solids consisting of 5-16 nm PbTe QDs encapsulated by CdTe shells. Colloidally synthesized PbTe QDs were first converted into core-shell PbTe/CdTe QDs, and then deposited as thin films. The subsequent fusion of the CdTe shells is achieved by ligand removal and annealing in the presence of CdCl2 . Contrary to highly unstable bare PbTe QDs, PbTe/CdTe QD solids exhibit bright and stable near- to mid-infrared emission at wavelengths of 1-3 μm, which is also retained upon prolonged storage at ambient conditions for one year.

  5. Air-Stable, Near- to Mid-Infrared Emitting Solids of PbTe/CdTe Core-Shell Colloidal quantum dots.

    PubMed

    Protesescu, Loredana; Zünd, Tanja; Bodnarchuk, Maryna I; Kovalenko, Maksym V

    2016-03-01

    Light emitters and detectors operating in the near- and mid-infrared spectral regions are important to many applications, such as telecommunications, high-resolution gas analysis, atmospheric pollution monitoring, medical diagnostics, and night vision. Various lead chalcogenides (binary, ternary, and quaternary alloys) in the form of quantum dots (QDs) or quantum wells provide narrow bandgap energies that cover the broad infrared region corresponding to wavelengths of 1-30 μm. Here, we report an inexpensive, all-solution-based synthesis strategy to thin-film solids consisting of 5-16 nm PbTe QDs encapsulated by CdTe shells. Colloidally synthesized PbTe QDs were first converted into core-shell PbTe/CdTe QDs, and then deposited as thin films. The subsequent fusion of the CdTe shells is achieved by ligand removal and annealing in the presence of CdCl2 . Contrary to highly unstable bare PbTe QDs, PbTe/CdTe QD solids exhibit bright and stable near- to mid-infrared emission at wavelengths of 1-3 μm, which is also retained upon prolonged storage at ambient conditions for one year. PMID:26676076

  6. On the role of the porous shell of the solid core of the earth in the anomalous heat and mass flow to the mantle

    SciTech Connect

    Pikin, S. A.

    2013-03-15

    The model of the pressure-induced first-order phase transition of a metal melt to the metallicglass state considers a thermodynamically nonequilibrium porous near-surface shell of the solid core of the Earth, which contacts cyclonic vortices in the liquid core. Anomalous flows of heat and light-material mass to the mantle from the solid core at these contact points are calculated. These anomalous flows are shown to be comparable with the observed ones under the assumption of a rapid increase in the melt viscosity at pressures of 1-10 Mbar, which is characteristic of a solid core. In this case, the porous layer permeability may be very low.

  7. TECHNICAL NOTE: The formulation of a refined hybrid enhanced assumed strain solid shell element and its application to model smart structures containing distributed piezoelectric sensors/actuators

    NASA Astrophysics Data System (ADS)

    Zheng, Shijie; Wang, Xinwei; Chen, Wanji

    2004-08-01

    In the present paper, a novel refined hybrid piezoelectric element formulation is developed for mechanical analysis and active vibration control of laminated structures bonded to piezoelectric sensors and actuators. By invoking the electrical field potential equation, a 'quasi-decoupling' method for treating the coupling electromechanical effects is presented and a modified generalized variational principle with a weaker interelement continuity condition is proposed. On the basis of this functional, a general formulation for a refined hybrid piezoelectric element method is established by incorporating an orthogonal interpolation approach and enhanced assumed strain (EAS) modes. A linearly distributed transverse EAS in the thickness direction is adopted to overcome the thickness locking of solid shell elements. Compared with the conventional incompatible brick element approach, the present formulation is very reliable, more accurate, computationally efficient and can be used to model the response of thin plates and shell structures.

  8. Simulation of the solid state and the first and second hydration shell of the xanthine oxidase inhibitor allopurinol: Structures obtained using DFT and MP2 methods

    NASA Astrophysics Data System (ADS)

    Álvarez-Ros, M. C.; Alcolea Palafox, M.

    2016-05-01

    Allopurinol (AL) was investigated in the isolated state, solid state, and in the hydrated form through an exhaustive quantum-chemical analysis. Full geometry optimization and energy calculations of the 11 most stable tautomers in the isolated state were performed. The most stable one corresponds to AL-15 at all the levels of computation. Several weak bands of the experimental spectrum in Ar-matrix were tentatively assigned to tautomer AL-25. The crystal unit cell of the solid state was simulated by a heptamer form. Comparisons with the experimental values confirm that only tautomer AL-15 appears in the solid state. The hydration of the two most stable tautomers: AL-15 and AL-25 was carried out. Solvent effects were considered using the Tomasi's polarized continuum model (PCM) and by the explicit model (EM) including a variable number of water molecules surrounding the base to simulate the first and second hydration shells. In this second hydration shell the calculated difference in the free energy between both tautomers is so small, that both tautomers can coexist in bull water. Some of the most important conclusions on the effects of the hydration on the molecular structure were presented. The deformation and interaction energies were corrected for basis set superposition error (BSSE) using the counterpoise (CP) procedure.

  9. Preparation of hollow microsphere@onion-like solid nanosphere MoS2 coated by a carbon shell as a stable anode for optimized lithium storage

    NASA Astrophysics Data System (ADS)

    Guo, Bangjun; Yu, Ke; Song, Haili; Li, Honglin; Tan, Yinghua; Fu, Hao; Li, Chao; Lei, Xiang; Zhu, Ziqiang

    2015-12-01

    A one-step hydrothermal method was successfully used to fabricate hollow microsphere@onion-like solid nanosphere MoS2. Then the as-prepared sS-MoS2 was decorated with a carbon shell using dopamine as a carbon source by a facile route, resulting in hollow microsphere@onion-like solid nanosphere MoS2 decorated with carbon shell (sS-MoS2@C). A synergistic effect was observed for the two-component material, leading to new electrochemical processes for lithium storage, with improved electroconductivity and structural soundness, triggering an ascending capacity upon cycling. The as-prepared sS-MoS2@C exhibits optimized electrochemical behaviour with high specific capacity (1107 mA h g-1 at 100 mA g-1), superior high-rate capability (805 mA h g-1 at 5000 mA g-1) and good cycling stability (91.5% of capacity retained after 100 cycles), suggesting its potential application in high-energy lithium-ion batteries.A one-step hydrothermal method was successfully used to fabricate hollow microsphere@onion-like solid nanosphere MoS2. Then the as-prepared sS-MoS2 was decorated with a carbon shell using dopamine as a carbon source by a facile route, resulting in hollow microsphere@onion-like solid nanosphere MoS2 decorated with carbon shell (sS-MoS2@C). A synergistic effect was observed for the two-component material, leading to new electrochemical processes for lithium storage, with improved electroconductivity and structural soundness, triggering an ascending capacity upon cycling. The as-prepared sS-MoS2@C exhibits optimized electrochemical behaviour with high specific capacity (1107 mA h g-1 at 100 mA g-1), superior high-rate capability (805 mA h g-1 at 5000 mA g-1) and good cycling stability (91.5% of capacity retained after 100 cycles), suggesting its potential application in high-energy lithium-ion batteries. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr05595d

  10. Facile preparation of surface-exchangeable core@shell iron oxide@gold nanoparticles for magnetic solid-phase extraction: use of gold shell as the intermediate platform for versatile adsorbents with varying self-assembled monolayers.

    PubMed

    Li, Yaping; Qi, Li; Shen, Ying; Ma, Huimin

    2014-02-01

    The core@shell Fe3O4@Au nanoparticles (NPs) functionalized with exchangeable self-assembled monolayers have been developed for mode switching magnetic solid-phase extraction (MSPE) using high performance liquid chromatography with ultraviolet detection. The adsorbents were synthesized by chemical coprecipitation to prepare magnetic cores followed by sonolysis to produce gold shells. Functionalization of Fe3O4@Au NPs surface was realized through self-assembly of commercially available low molecular weight thiol-containing ligands using gold shells as intermediate platform and the dynamic nature of Au-S chemistry allowed substituent of one thiol-containing ligand with another simply by thiol exchange process. The resultant adsorbents were characterized by transmission electronic microscopy, Fourier transform infrared spectroscopy, elemental analysis, contact angle measurement, and vibrating sample magnetometry. To evaluate the versatile performance of the developed MSPE adsorbents, they were applied for normal-phase SPE followed by reversed-phase SPE. A few kinds of diphenols and polycyclic aromatic hydrocarbons (PAHs) were employed as model analytes, respectively. The predominant parameters affecting extraction efficiency were investigated and optimized. Under the optimum experimental conditions, wide dynamic linear range (6.25-1600 μg L(-1) for diphenols and 1.56-100 μg L(-1) for PAHs) with good linearity (r(2)≥0.989) and low detection limits (0.34-16.67 μg L(-1) for diphenols and 0.26-0.52 μg L(-1) for PAHs) were achieved. The advantage of the developed method is that the Fe3O4@Au NPs could be reutilized for preconcentrating diverse target analytes in different SPE modes sequentially simply through treatment with desired thiol-containing ligands.

  11. Preparation of hollow microsphere@onion-like solid nanosphere MoS2 coated by a carbon shell as a stable anode for optimized lithium storage.

    PubMed

    Guo, Bangjun; Yu, Ke; Song, Haili; Li, Honglin; Tan, Yinghua; Fu, Hao; Li, Chao; Lei, Xiang; Zhu, Ziqiang

    2016-01-01

    A one-step hydrothermal method was successfully used to fabricate hollow microsphere@onion-like solid nanosphere MoS2. Then the as-prepared sS-MoS2 was decorated with a carbon shell using dopamine as a carbon source by a facile route, resulting in hollow microsphere@onion-like solid nanosphere MoS2 decorated with carbon shell (sS-MoS2@C). A synergistic effect was observed for the two-component material, leading to new electrochemical processes for lithium storage, with improved electroconductivity and structural soundness, triggering an ascending capacity upon cycling. The as-prepared sS-MoS2@C exhibits optimized electrochemical behaviour with high specific capacity (1107 mA h g(-1) at 100 mA g(-1)), superior high-rate capability (805 mA h g(-1) at 5000 mA g(-1)) and good cycling stability (91.5% of capacity retained after 100 cycles), suggesting its potential application in high-energy lithium-ion batteries. PMID:26620104

  12. Equilibrium K-, L-, and M-shell ionizations and charge-state distribution of sulfur projectiles passing through solid targets

    SciTech Connect

    Braziewicz, J.; Majewska, U.; Banas, D.; Polasik, M.; Slabkowska, K.; Koziol, K.; Jaskola, M.; Korman, A.; Kretschmer, W.; Choinski, J.

    2010-08-15

    In the present work, an alternative approach for the evaluation of the equilibrium K-, L-, and M-shell ionizations and the mean charge state q for projectiles passing through various targets has been proposed. The approach is based on measured K x-ray energy shifts and line intensity ratios and utilizes the theoretical analysis of projectile spectra using multiconfiguration Dirac-Fock calculations. It was applied for the satellite and hypersatellite K lines in the x-ray spectra emitted by sulfur projectiles passing with energies of 9.6-122 MeV through carbon, aluminium, titanium, and iron targets, recorded by a Si(Li) detector. It was found that only in the high projectile energy region there was significant dependence of mean equilibrium K-shell ionization on the target atomic number. The equilibrium L-shell ionization rises with the increase of sulfur energy until 32 MeV, but for higher energies the changes are very weak. The equilibrium M-shell ionization changes very weakly for low projectile energy while for higher energies this ionization is practically constant. For each target, the estimated value of q rises with the increase of the sulfur energy value. The dependence of the sulfur charge state on the target atomic number was discussed by taking into account the cross sections for ionization, decay, and electron capture processes. The data were compared with the experimental data measured by other authors and with the predictions of Shima's and Schiwietz and Grande's semiempirical formulas. The presented good agreement points out that this alternative approach delivers quantitative results.

  13. L-shell emission from high-Z solid targets by intense 10{sup 19}W/cm{sup 2} irradiation with a 248nm laser

    SciTech Connect

    Nelson, T.R.; Borisov, A.B.; Boyer, K.

    2000-01-05

    Efficient (1.2% yield) multikilovolt x-ray emission from Ba(L) (2.4--2.8{angstrom}) and Gd(L) (1.7--2.1{angstrom}) is produced by ultraviolet (248nm) laser-excited BaF{sub 2} and Gd solids. The high efficiency is attributed to an inner shell-selective collisional electron ejection. Much effort has been expended recently in attempts to develop an efficient coherent x-ray source suitable for high-resolution biological imaging. To this end, many experiments have been performed studying the x-ray emissions from high-Z materials under intense (>10{sup 18}W/cm{sup 2}) irradiation, with the most promising results coming from the irradiation of Xe clusters with a UV (248nm) laser at intensities of 10{sup 18}--10{sup 19}W/cm{sup 2}. In this paper the authors report the production of prompt x-rays with energies in excess of 5keV with efficiencies on the order of 1% as a result of intense irradiation of BaF{sub 2} and Gd targets with a terawatt 248nm laser. The efficiency is attributed to an inner shell-selective collisional electron ejection mechanism in which the previously photoionized electrons are ponderomotively driven into an ion while retaining a portion of their atomic phase and symmetry. This partial coherence of the laser-driven electrons has a pronounced effect on the collisional cross-section for the electron ion interaction.

  14. Synthesis and characterization of core-shell magnetic molecularly imprinted polymers for solid-phase extraction and determination of Rhodamine B in food.

    PubMed

    Su, Xiaomeng; Li, Xiaoyan; Li, Junjie; Liu, Min; Lei, Fuhou; Tan, Xuecai; Li, Pengfei; Luo, Weiqiang

    2015-03-15

    Core-shell magnetic molecularly imprinted polymers (MIPs) nanoparticles (NPs), in which a Rhodamine B-imprinted layer was coated on Fe3O4 NPs. were synthesized. First, Fe3O4 NPs were prepared by a coprecipitation method. Then, amino-modified Fe3O4 NPs (Fe3O4@SiO2-NH2) was prepared. Finally, the MIPs were coated on the Fe3O4@SiO2-NH2 surface by the copolymerization with functional monomer, acrylamide, using a cross-linking agent, ethylene glycol dimethacrylate; an initiator, azobisisobutyronitrile and a template molecule, Rhodamine B. The Fe3O4@MIPs were characterized using a scanning electron microscope, Fourier transform infrared spectrometer, vibrating sample magnetometer, and re-binding experiments. The Fe3O4@MIPs showed a fast adsorption equilibrium, a highly improved imprinting capacity, and significant selectivity; they could be used as a solid-phase extraction material and detect illegal addition Rhodamine B in food. A method was developed for the selective isolation and enrichment of Rhodamine B in food samples with recoveries in the range 78.47-101.6% and the relative standard deviation was <2%.

  15. Foam shell cryogenic ICF target

    DOEpatents

    Darling, Dale H.

    1987-01-01

    A uniform cryogenic layer of DT fuel is maintained in a fusion target having a low density, small pore size, low Z rigid foam shell saturated with liquid DT fuel. Capillary action prevents gravitational slumping of the fuel layer. The saturated shell may be cooled to produce a solid fuel layer.

  16. Elastic platonic shells.

    PubMed

    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.

  17. Generation of a mesoporous silica MSU shell onto solid core silica nanoparticles using a simple two-step sol-gel process.

    PubMed

    Allouche, Joachim; Dupin, Jean-Charles; Gonbeau, Danielle

    2011-07-14

    Silica core-shell nanoparticles with a MSU shell have been synthesized using several non-ionic poly(ethylene oxide) based surfactants via a two step sol-gel method. The materials exhibit a typical worm-hole pore structure and tunable pore diameters between 2.4 nm and 5.8 nm.

  18. Radiography of magnetically-driven implosions of initially solid beryllium cylindrical shells for equation-of-state studies at the Z pulsed-power facility

    NASA Astrophysics Data System (ADS)

    McBride, Ryan

    2011-06-01

    The Z accelerator delivers approximately 4-MV, 26-MA electrical pulses with adjustable current rise times of 100--600 ns, as well as adjustable pulse waveforms. The magnetic pressure produced is used for various applications, including magnetically-driven implosions. The Z-Beamlet Laser (ZBL) is a pulsed (0.3-1.5 ns), multi-kJ, TW-class Nd:glass laser system that provides x-ray radiography capabilities for Z experiments. This talk focuses primarily on the radiography diagnostic used to study the magnetically-driven implosions of initially solid cylindrical shells (also referred to as ``liners''). Specifically, we discuss the 6.151-keV monochromatic backlighting system and its use in obtaining radiographs of imploding beryllium (Be) liners. The high transmission efficiency of 6.151-keV photons in Be allowed us to obtain radiographs with finite transmission throughout the radial extent of the imploding liners. Abel inverting these data, we have obtained time-resolved measurements of the imploding liner's density as a function of both axial and radial location throughout the field of view. These data are allowing us to study magneto-Rayleigh-Taylor (MRT) growth for inertial-confinement-fusion applications, as well as compression-wave propagation for equation-of-state studies (see talks by R.L. Lemke and M.R. Martin). Additionally, Z's pulse-shaping capabilities have enabled us to obtain data for both shock- and quasi-isentropically-compressed Be. Example data from MRT, shock-compression, and quasi-isentropic-compression experiments will be shown. We will also discuss planned upgrades to 25-keV radiography that will allow us to study materials with opacities beyond that of beryllium. This work was done in collaboration with R.W. Lemke, M.R. Martin, J.-P. Davis, M.D. Knudson, D.B. Sinars, S.A. Slutz, C.A. Jennings, M.E. Cuneo, D.G. Flicker, and M.C. Herrmann. Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed-Martin company, for the US

  19. Enrichment and determination of polybrominated diphenyl ethers in environmental water samples by magnetic solid-phase extraction with core-shell magnetic carbon microspheres before gas chromatography with mass spectrometry.

    PubMed

    Zhou, Jia-Bin; She, Xiao-Kun; Xing, Han-Zhu; Wang, Xia; Zhao, Ru-Song

    2016-05-01

    Core-shell magnetic carbon microspheres were synthesized by a simple hydrothermal method and used as a novel magnetic solid-phase extraction adsorbent for the sensitive determination of polybrominated diphenyl ethers in environmental water samples. Gas chromatography with negative chemical ionization mass spectrometry was adopted for the detection. Box-Behnken design was used to investigate and optimize important magnetic solid-phase extraction parameters through response surface methodology. Under the optimal conditions, low limits of detection (0.07-0.17 ng·L(-1) ), a wide linear range (1-1000 ng·L(-1) ), and good repeatability (0.80-4.58%) were achieved. The developed method was validated with several real water samples, and satisfactory results were obtained in the range of 72.8-97.9%. These results indicated that core-shell magnetic carbon microspheres have great potential as an adsorbent for the magnetic solid-phase extraction of polybrominated diphenyl ethers at trace levels from environmental water samples.

  20. Sensational spherical shells

    SciTech Connect

    Lee, M.C.; Kendall, J.M.,JR.; Bahrami, P.A.; Wang, T.G.

    1986-01-01

    Fluid-dynamic and capillary forces can be used to form nearly perfect, very small spherical shells when a liquid that can solidify is passed through an annular die to form an annular jet. Gravity and certain properties of even the most ideal materials, however, can cause slight asymmetries. The primary objective of the present work is the control of this shell formation process in earth laboratories rather than space microgravity, through the development of facilities and methods that minimize the deleterious effects of gravity, aerodynamic drag, and uncontrolled cooling. The spherical shells thus produced can be used in insulation, recyclable filter materials, fire retardants, explosives, heat transport slurries, shock-absorbing armor, and solid rocket motors.

  1. MVC Shell

    2008-06-03

    Provides the shell of a plugin based application environment that builds on MVC Framework to allow one to rapidly construct an application by using a collection of plugins. The MVC Shell is implemented in C# as a .NET 2.0 application that can then be used as a shell for building a plugin based application. The infrastructure allows for dynamically processing a specified collection of plugins in order to determine the functionality of the application, wheremore » all plugins operate within the context of the underlying MVC Framework environment.« less

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

    NASA Technical Reports Server (NTRS)

    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.

  3. Core-shell SiO2 -coated Fe3 O4 with a surface molecularly imprinted polymer coating of folic acid and its applicable magnetic solid-phase extraction prior to determination of folates in tomatoes.

    PubMed

    Areerob, Yonrapach; Sricharoen, Phitchan; Limchoowong, Nunticha; Chanthai, Saksit

    2016-08-01

    A novel core-shell magnetic surface molecularly imprinted polymer with folic acid as a template was successfully synthesized by the sol-gel method. To generate Lewis acid sites in the silica matrix for the interaction of the metal coordinate with the template, 3-aminopropyltriethoxysilane was used as a functional monomer, tetraethyl orthosilicate as a cross-linker, and aluminum ions as a dopant. The magnetite encapsulated by the silica shell plays an important role as a magnetic-coated polymer. The synthesized product was characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and FTIR and UV/Vis spectroscopy. The powder X-ray diffraction patterns, FTIR and UV/Vis spectra confirmed the characteristics of the as-prepared silica coated magnetite and folic acid molecularly imprinted polymer. It was successfully applied for magnetic solid-phase extraction prior to the determination of folates in tomato samples using high-performance liquid chromatography with photodiode array detection. The detection limit of the proposed method was 1.67 μg/L, and results were satisfactory, with a relative standard deviation of < 3.94%. PMID:27296679

  4. Metal-organic framework UiO-66 modified magnetite@silica core-shell magnetic microspheres for magnetic solid-phase extraction of domoic acid from shellfish samples.

    PubMed

    Zhang, Wenmin; Yan, Zhiming; Gao, Jia; Tong, Ping; Liu, Wei; Zhang, Lan

    2015-06-26

    Fe3O4@SiO2@UiO-66 core-shell magnetic microspheres were synthesized and characterized by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectrometry, vibrating sample magnetometry, nitrogen adsorption porosimetry and zeta potential analyzer. The synthesized Fe3O4@SiO2@UiO-66 microspheres were first used for magnetic solid-phase extraction (MSPE) of domoic acid (DA) in shellfish samples. Combined with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), a fast, simple and sensitive method for the determination of DA was established successfully. Under the optimized conditions, the developed method showed short analysis time, good linearity (r(2) = 0.9990), low limit of detection (1.45 pg mL(-1); S/N = 3:1), low limit of quantification (4.82 pg mL(-1); S/N = 10:1), and good extraction repeatability (RSD ≤ 5.0%; n = 5). Real shellfish samples were processed using the developed method, and trace level of DA was detected. The results demonstrate that Fe3O4@SiO2@UiO-66 core-shell magnetic microspheres are the promising sorbents for rapid and efficient extraction of polar analytes from complex biological samples. PMID:25997847

  5. Vibration of Shells

    NASA Technical Reports Server (NTRS)

    Leissa, A. W.

    1973-01-01

    The vibrational characteristics and mechanical properties of shell structures are discussed. The subjects presented are: (1) fundamental equations of thin shell theory, (2) characteristics of thin circular cylindrical shells, (3) complicating effects in circular cylindrical shells, (4) noncircular cylindrical shell properties, (5) characteristics of spherical shells, and (6) solution of three-dimensional equations of motion for cylinders.

  6. Building Atoms Shell by Shell.

    ERIC Educational Resources Information Center

    Sussman, Beverly

    1993-01-01

    Describes an atom-building activity where students construct three-dimensional models of atoms using a styrofoam ball as the nucleus and pom-poms, gum drops, minimarshmallows, or other small items of two different colors to represent protons and neutrons attached. Rings of various sizes with pom-poms attached represent electron shells and…

  7. Shell worlds

    NASA Astrophysics Data System (ADS)

    Roy, Kenneth I.; Kennedy, Robert G., III; Fields, David E.

    2013-02-01

    The traditional concept of terraforming assumes ready availability of candidate planets with acceptable qualities: orbiting a star in its "Goldilocks zone", liquid water, enough mass, years longer than days, magnetic field, etc. But even stipulating affordable interstellar travel, we still might never find a good candidate elsewhere. Whatever we found likely would require centuries of heavy terraforming, just as Mars or Venus would here. Our increasing appreciation of the ubiquity of life suggests that any terra nova would already possess it. We would then face the dilemma of introducing alien life forms (us, our microbes) into another living world. Instead, we propose a novel method to create habitable environments for humanity by enclosing airless, sterile, otherwise useless planets, moons, and even large asteroids within engineered shells, which avoids the conundrum. These shells are subject to two opposing internal stresses: compression due to the primary's gravity, and tension from atmospheric pressure contained inside. By careful design, these two cancel each other resulting in zero net shell stress. Beneath the shell an Earth-like environment could be created similar in almost all respects to that of Home, except for gravity, regardless of the distance to the sun or other star. Englobing a small planet, moon, or even a dwarf planet like Ceres, would require astronomical amounts of material (quadrillions of tons) and energy, plus a great deal of time. It would be a quantum leap in difficulty over building Dyson Dots or industrializing our solar system, perhaps comparable to a mission across interstellar space with a living crew within their lifetime. But when accomplished, these constructs would be complete (albeit small) worlds, not merely large habitats. They could be stable across historic timescales, possibly geologic. Each would contain a full, self-sustaining ecology, which might evolve in curious directions over time. This has interesting implications

  8. Computational design and fabrication of core-shell magnetic molecularly imprinted polymer for dispersive micro-solid-phase extraction coupled with high-performance liquid chromatography for the determination of rhodamine 6G.

    PubMed

    Xie, Jin; Xie, Jie; Deng, Jian; Fang, Xiangfang; Zhao, Haiqing; Qian, Duo; Wang, Hongjuan

    2016-06-01

    A novel core-shell magnetic nano-adsorbent with surface molecularly imprinted polymer coating was fabricated and then applied to dispersive micro-solid-phase extraction followed by determination of rhodamine 6G using high-performance liquid chromatography. The molecularly imprinted polymer coating was prepared by copolymerization of dopamine and m-aminophenylboronic acid (functional monomers), in the presence of rhodamine 6G (template). The selection of the suitable functional monomers was based on the interaction between different monomers and the template using the density functional theory. The ratios of the monomers to template were further optimized by an OA9 (3(4) ) orthogonal array design. The binding performances of the adsorbent were evaluated by static, kinetic, and selective adsorption experiments. The results reveal that the adsorbent possesses remarkable affinity and binding specificity for rhodamine 6G because of the enhanced Lewis acid-base interaction between the B(Ш) embedded in the imprinted cavities and the template. The nano-adsorbent was successfully applied to dispersive micro-solid-phase extraction coupled to high-performance liquid chromatography for the trace determination of rhodamine 6G in samples with a detection limit of 2.7 nmol/L. Spiked recoveries ranged from 93.0-99.1, 89.5-92.7, and 86.9-105% in river water, matrimony vine and paprika samples, respectively, with relative standard deviations of less than 4.3%. PMID:27120290

  9. In situ fabrication of high-performance Ni-GDC-nanocube core-shell anode for low-temperature solid-oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Yamamoto, Kazuhiro; Qiu, Nan; Ohara, Satoshi

    2015-11-01

    A core-shell anode consisting of nickel-gadolinium-doped-ceria (Ni-GDC) nanocubes was directly fabricated by a chemical process in a solution containing a nickel source and GDC nanocubes covered with highly reactive {001} facets. The cermet anode effectively generated a Ni metal framework even at 500 °C with the growth of the Ni spheres. Anode fabrication at such a low temperature without any sintering could insert a finely nanostructured layer close to the interface between the electrolyte and the anode. The maximum power density of the attractive anode was 97 mW cm-2, which is higher than that of a conventional NiO-GDC anode prepared by an aerosol process at 55 mW cm-2 and 600 °C, followed by sintering at 1300 °C. Furthermore, the macro- and microstructure of the Ni-GDC-nanocube anode were preserved before and after the power-generation test at 700 °C. Especially, the reactive {001} facets were stabled even after generation test, which served to reduce the activation energy for fuel oxidation successfully.

  10. In situ fabrication of high-performance Ni-GDC-nanocube core-shell anode for low-temperature solid-oxide fuel cells

    PubMed Central

    Yamamoto, Kazuhiro; Qiu, Nan; Ohara, Satoshi

    2015-01-01

    A core–shell anode consisting of nickel–gadolinium-doped-ceria (Ni–GDC) nanocubes was directly fabricated by a chemical process in a solution containing a nickel source and GDC nanocubes covered with highly reactive {001} facets. The cermet anode effectively generated a Ni metal framework even at 500 °C with the growth of the Ni spheres. Anode fabrication at such a low temperature without any sintering could insert a finely nanostructured layer close to the interface between the electrolyte and the anode. The maximum power density of the attractive anode was 97 mW cm–2, which is higher than that of a conventional NiO–GDC anode prepared by an aerosol process at 55 mW cm–2 and 600 °C, followed by sintering at 1300 °C. Furthermore, the macro- and microstructure of the Ni–GDC-nanocube anode were preserved before and after the power-generation test at 700 °C. Especially, the reactive {001} facets were stabled even after generation test, which served to reduce the activation energy for fuel oxidation successfully. PMID:26615816

  11. In situ fabrication of high-performance Ni-GDC-nanocube core-shell anode for low-temperature solid-oxide fuel cells.

    PubMed

    Yamamoto, Kazuhiro; Qiu, Nan; Ohara, Satoshi

    2015-11-30

    A core-shell anode consisting of nickel-gadolinium-doped-ceria (Ni-GDC) nanocubes was directly fabricated by a chemical process in a solution containing a nickel source and GDC nanocubes covered with highly reactive {001} facets. The cermet anode effectively generated a Ni metal framework even at 500 °C with the growth of the Ni spheres. Anode fabrication at such a low temperature without any sintering could insert a finely nanostructured layer close to the interface between the electrolyte and the anode. The maximum power density of the attractive anode was 97 mW cm(-2), which is higher than that of a conventional NiO-GDC anode prepared by an aerosol process at 55 mW cm(-2) and 600 °C, followed by sintering at 1300 °C. Furthermore, the macro- and microstructure of the Ni-GDC-nanocube anode were preserved before and after the power-generation test at 700 °C. Especially, the reactive {001} facets were stabled even after generation test, which served to reduce the activation energy for fuel oxidation successfully.

  12. New chrysin-functionalized silica-core shell magnetic nanoparticles for the magnetic solid phase extraction of copper ions from water samples.

    PubMed

    Abd Ali, Layth Imad; Ibrahim, Wan Aini Wan; Sulaiman, Azli; Kamboh, Muhammad Afzal; Sanagi, Mohd Marsin

    2016-01-01

    This study describes the synthesis, characterization and application of a new chrysin-based silica core-shell magnetic nanoparticles (Fe3O4@SiO2-N-chrysin) as an adsorbent for the preconcentration of Cu(II) from aqueous environment. The morphology, thermal stability and magnetic property of Fe3O4@SiO2-N-chrysin were analyzed using FTIR, FESEM, TEM, XRD, thermal analysis and VSM. The extraction efficiency of Fe3O4@SiO2-N-chrysin was analyzed using the batch wise method with flame atomic absorption spectrometry. Parameters such as the pH, the sample volume, the adsorption-desorption time, the concentration of the desorption solvent, the desorption volume, the interference effects and the regeneration of the adsorbent were optimized. It was determined that Cu(II) adsorption is highly pH-dependent, and a high recovery (98%) was achieved at a pH 6. The limit of detection (S/N=3), the limit of quantification (S/N=10), the preconcentration factor and the relative standard deviation for Cu(II) extraction were 0.3 ng mL(-1), 1 ng mL(-1), 100 and 1.9% (concentration=30 ng mL(-1), n=7), respectively. Excellent relative recoveries of 97-104% (%RSD<3.12) were achieved from samples from a spiked river, a lake and tap water. The MSPE method was also validated using certified reference materials SLRS-5 with good recovery (92.53%).

  13. Magnetic solid phase extraction using ionic liquid-coated core-shell magnetic nanoparticles followed by high-performance liquid chromatography for determination of Rhodamine B in food samples.

    PubMed

    Chen, Jieping; Zhu, Xiashi

    2016-06-01

    Three hydrophobic ionic liquids (ILs) (1-butyl-3-methylimidazole hexafluorophosphate ([BMIM]PF6), 1-hexyl-3-methyl-imidazole hexafluoro-phosphate ([HMIM]PF6), and 1-octyl-3-methylimidazole hexafluorophosphate ([OMIM]PF6)) were used to coat Fe3O4@SiO2 nanoparticles (NPs) with core-shell structures to prepare magnetic solid phase extraction (MSPE) agents (Fe3O4@SiO2@IL). A novel method of MSPE coupled with high-performance liquid chromatography for the separation/analysis of Rhodamine B was then established. The results showed that Rhodamine B was adsorbed rapidly on Fe3O4@SiO2@[OMIM]PF6 and was released using ethanol. Under optimal conditions, the pre-concentration factor for the proposed method was 25. The linear range, limit of detection (LOD), correlation coefficient (R), and relative standard deviation (RSD) were found to be 0.50-150.00 μgL(-1), 0.08 μgL(-1), 0.9999, and 0.51% (n=3, c=10.00 μgL(-1)), respectively. The Fe3O4@SiO2 NPs could be re-used up to 10 times. The method was successfully applied to the determination of Rhodamine B in food samples. PMID:26830554

  14. Magnetic solid phase extraction using ionic liquid-coated core-shell magnetic nanoparticles followed by high-performance liquid chromatography for determination of Rhodamine B in food samples.

    PubMed

    Chen, Jieping; Zhu, Xiashi

    2016-06-01

    Three hydrophobic ionic liquids (ILs) (1-butyl-3-methylimidazole hexafluorophosphate ([BMIM]PF6), 1-hexyl-3-methyl-imidazole hexafluoro-phosphate ([HMIM]PF6), and 1-octyl-3-methylimidazole hexafluorophosphate ([OMIM]PF6)) were used to coat Fe3O4@SiO2 nanoparticles (NPs) with core-shell structures to prepare magnetic solid phase extraction (MSPE) agents (Fe3O4@SiO2@IL). A novel method of MSPE coupled with high-performance liquid chromatography for the separation/analysis of Rhodamine B was then established. The results showed that Rhodamine B was adsorbed rapidly on Fe3O4@SiO2@[OMIM]PF6 and was released using ethanol. Under optimal conditions, the pre-concentration factor for the proposed method was 25. The linear range, limit of detection (LOD), correlation coefficient (R), and relative standard deviation (RSD) were found to be 0.50-150.00 μgL(-1), 0.08 μgL(-1), 0.9999, and 0.51% (n=3, c=10.00 μgL(-1)), respectively. The Fe3O4@SiO2 NPs could be re-used up to 10 times. The method was successfully applied to the determination of Rhodamine B in food samples.

  15. Improved Performance of Dye-Sensitized Solar Cells Fabricated from a Coumarin NKX-2700 Dye-Sensitized TiO2/MgO Core-Shell Photoanode with an HfO2 Blocking Layer and a Quasi-Solid-State Electrolyte

    NASA Astrophysics Data System (ADS)

    Maheswari, D.; Venkatachalam, P.

    2015-03-01

    Dye sensitized solar cells (DSSC) were fabricated from a coumarin NKX-2700 dye-sensitized core-shell photoanode and a quasi-solid-state electrolyte, sandwiched together, with a cobalt sulfide-coated counter electrode. The core-shell photoanode consisted of a composite mixture of 90% TiO2 nanoparticles and 10% TiO2 nanowires (TNPW) as core layer and MgO nanoparticles (MNP) as shell layer. Hafnium oxide (HfO2) was applied to the core-shell photoanode film as a blocking layer. TiO2 nanoparticles, TiO2 nanowires, and TNPW/MNP were characterized by x-ray diffractometry, scanning electron microscopy, and transmission electron microscopy. It was apparent from the UV-visible spectrum of the sensitizing dye coumarin NKX-2700 that its absorption was maximum at 525 nm. Power conversion efficiency (PCE) was greater for DSSC-1, fabricated with a core-shell TNPW/MNP/HfO2 photoanode, than for the other DSSC; its photovoltaic properties were: short circuit photocurrent J sc = 19 mA/cm2, open circuit voltage ( V oc) = 720 mV, fill factor ( FF) = 66%, and PCE ( η) = 9.02%. The charge-transport and charge-recombination behavior of the DSSC were investigated by electrochemical impedance spectroscopy; the results showed that the composite core-shell film resulted in the lowest charge-transfer resistance ( R CE) and the longest electron lifetime ( τ eff). Hence, the improved performance of DSSC-1 could be ascribed to the core-shell photoanode with blocking layer, which increased electron transport and suppressed recombination of charge carriers at the photoanode/dye/electrolyte interface.

  16. Solid Phase Characterization of Solids Recovered from Failed Sluicer Arm

    SciTech Connect

    Cooke, Gary A.

    2015-03-09

    The Enclosure to this memo discusses the solid phase characterization of a solid sample that was retrieved from the single-shell Tank 241-C-111 extended reach sluicer #2. This sluicer, removed from riser #3 on September 25, 2014, was found to have approximately 0.4 gallons of solid tank waste adhering to the nozzle area.

  17. Prediction of Path Deviation in Robot Based Incremental Sheet Metal Forming by Means of a New Solid-Shell Finite Element Technology and a Finite Elastoplastic Model with Combined Hardening

    NASA Astrophysics Data System (ADS)

    Kiliclar, Yalin; Laurischkat, Roman; Vladimirov, Ivaylo N.; Reese, Stefanie

    2011-08-01

    The presented project deals with a robot based incremental sheet metal forming process, which is called roboforming and has been developed at the Chair of Production Systems. It is characterized by flexible shaping using a freely programmable path-synchronous movement of two industrial robots. The final shape is produced by the incremental infeed of the forming tool in depth direction and its movement along the part contour in lateral direction. However, the resulting geometries formed in roboforming deviate several millimeters from the reference geometry. This results from the compliance of the involved machine structures and the springback effects of the workpiece. The project aims to predict these deviations caused by resiliences and to carry out a compensative path planning based on this prediction. Therefore a planning tool is implemented which compensates the robots's compliance and the springback effects of the sheet metal. The forming process is simulated by means of a finite element analysis using a material model developed at the Institute of Applied Mechanics (IFAM). It is based on the multiplicative split of the deformation gradient in the context of hyperelasticity and combines nonlinear kinematic and isotropic hardening. Low-order finite elements used to simulate thin sheet structures, such as used for the experiments, have the major problem of locking, a nonphysical stiffening effect. For an efficient finite element analysis a special solid-shell finite element formulation based on reduced integration with hourglass stabilization has been developed. To circumvent different locking effects, the enhanced assumed strain (EAS) and the assumed natural strain (ANS) concepts are included in this formulation. Having such powerful tools available we obtain more accurate geometries.

  18. Theory of conformational transitions of viral shells

    NASA Astrophysics Data System (ADS)

    Guérin, Thomas; Bruinsma, Robijn

    2007-12-01

    We propose a continuum theory for the conformational transitions of viral shells. Conformational transitions of viral shells, as encountered during viral maturation, are associated with a soft mode instability of the capsid proteins [F. Tama and C. L. Brooks, J. Mol. Biol. 345(2), 299 (2005)]. The continuum theory presented here is an adaptation of the Ginzburg-Landau theory of soft-mode structural phase transitions of solids to viral shells. The theory predicts that the conformational transitions are characterized by a pronounced softening of the shell elasticity in the critical region. We demonstrate that the thermodynamics of the conformational transition can be probed quantitatively by a micromechanical atomic force microscope study. The external force can drive a capsid into a state of phase coexistence characterized by a highly nonlinear force deformation curve.

  19. Classification Shell Game.

    ERIC Educational Resources Information Center

    Etzold, Carol

    1983-01-01

    Discusses shell classification exercises. Through keying students advanced from the "I know what a shell looks like" stage to become involved in the classification process: observing, labeling, making decisions about categories, and identifying marine animals. (Author/JN)

  20. Photon upconversion in core-shell nanoparticles.

    PubMed

    Chen, Xian; Peng, Denfeng; Ju, Qiang; Wang, Feng

    2015-03-21

    Photon upconversion generally results from a series of successive electronic transitions within complex energy levels of lanthanide ions that are embedded in the lattice of a crystalline solid. In conventional lanthanide-doped upconversion nanoparticles, the dopant ions homogeneously distributed in the host lattice are readily accessible to surface quenchers and lose their excitation energy, giving rise to weak and susceptible emissions. Therefore, present studies on upconversion are mainly focused on core-shell nanoparticles comprising spatially confined dopant ions. By doping upconverting lanthanide ions in the interior of a core-shell nanoparticle, the upconversion emission can be substantially enhanced, and the optical integrity of the nanoparticles can be largely preserved. Optically active shells are also frequently employed to impart multiple functionalities to upconversion nanoparticles. Intriguingly, the core-shell design introduces the possibility of constructing novel upconversion nanoparticles by exploiting the energy exchange interactions across the core-shell interface. In this tutorial review, we highlight recent advances in the development of upconversion core-shell nanoparticles, with particular emphasis on the emerging strategies for regulating the interplay of dopant interactions through core-shell nanostructural engineering that leads to unprecedented upconversion properties. The improved control over photon energy conversion will open up new opportunities for biological and energy applications. PMID:25058157

  1. The adsorption of rare earth ions using carbonized polydopamine nano shells

    DOE PAGES

    Sun, Xiaoqi; Luo, Huimin; Mahurin, Shannon Mark; Dai, Sheng; Liu, Rui; Hou, Xisen; Dai, Sheng

    2016-01-07

    Herein we report the structure effects of nano carbon shells prepared by carbonized polydopamine for rare earth elements (REEs) adsorption for the first time. The solid carbon sphere, 60 nm carbon shell and 500 nm carbon shell were prepared and investigated for adsorption and desorption of REEs. The adsorption of carbon shells for REEs was found to be better than the solid carbon sphere. The effect of acidities on the adsorption and desorption properties was discussed in this study. The good adsorption performance of carbon shells can be attributed to their porous structure, large specific surface area, amine group andmore » carbonyl group of dopamine.« less

  2. Fluctuating shells under pressure

    PubMed Central

    Paulose, Jayson; Vliegenthart, Gerard A.; Gompper, Gerhard; Nelson, David R.

    2012-01-01

    Thermal fluctuations strongly modify the large length-scale elastic behavior of cross-linked membranes, giving rise to scale-dependent elastic moduli. Whereas thermal effects in flat membranes are well understood, many natural and artificial microstructures are modeled as thin elastic shells. Shells are distinguished from flat membranes by their nonzero curvature, which provides a size-dependent coupling between the in-plane stretching modes and the out-of-plane undulations. In addition, a shell can support a pressure difference between its interior and its exterior. Little is known about the effect of thermal fluctuations on the elastic properties of shells. Here, we study the statistical mechanics of shape fluctuations in a pressurized spherical shell, using perturbation theory and Monte Carlo computer simulations, explicitly including the effects of curvature and an inward pressure. We predict novel properties of fluctuating thin shells under point indentations and pressure-induced deformations. The contribution due to thermal fluctuations increases with increasing ratio of shell radius to thickness and dominates the response when the product of this ratio and the thermal energy becomes large compared with the bending rigidity of the shell. Thermal effects are enhanced when a large uniform inward pressure acts on the shell and diverge as this pressure approaches the classical buckling transition of the shell. Our results are relevant for the elasticity and osmotic collapse of microcapsules. PMID:23150558

  3. Lithography-free shell-substrate isolation for core-shell GaAs nanowires.

    PubMed

    Haggren, Tuomas; Perros, Alexander Pyymaki; Jiang, Hua; Huhtio, Teppo; Kakko, Joona-Pekko; Dhaka, Veer; Kauppinen, Esko; Lipsanen, Harri

    2016-07-01

    A facile and scalable lithography-free technique(5) for the rapid construction of GaAs core-shell nanowires incorporating shell isolation from the substrate is reported. The process is based on interrupting NW growth and applying a thin spin-on-glass (SOG) layer to the base of the NWs and resuming core-shell NW growth. NW growth occurred in an atmospheric pressure metalorganic vapour phase epitaxy (MOVPE) system with gold nanoparticles used as catalysts for the vapour-liquid-solid growth. It is shown that NW axial core growth and radial shell growth can be resumed after interruption and even exposure to air. The SOG residues and native oxide layer that forms on the NW surface are shown to prevent or perturb resumption of epitaxial NW growth if not removed. Both HF etching and in situ annealing of the air-exposed NWs in the MOVPE were shown to remove the SOG residues and native oxide layer. While both procedures are shown capable of removing the native oxide and enabling resumption of epitaxial NW growth, in situ annealing produced the best results and allowed construction of pristine core-shell NWs. No growth occurred on SOG and it was observed that axial NW growth was more rapid when a SOG layer covered the substrate. The fabricated p-core/n-shell NWs exhibited diode behaviour upon electrical testing. The isolation of the NW shells from the substrate was confirmed by scanning electron microscopy and electrical measurements. The crystal quality of the regrown core-shell NWs was verified with a high resolution transmission electron microscope. The reported technique potentially provides a pathway using MOVPE for scalable and high-throughput production of shell-substrate isolated core-shell NWs on an industrial scale.

  4. Lithography-free shell-substrate isolation for core-shell GaAs nanowires

    NASA Astrophysics Data System (ADS)

    Haggren, Tuomas; Pyymaki Perros, Alexander; Jiang, Hua; Huhtio, Teppo; Kakko, Joona-Pekko; Dhaka, Veer; Kauppinen, Esko; Lipsanen, Harri

    2016-07-01

    A facile and scalable lithography-free technique5 for the rapid construction of GaAs core-shell nanowires incorporating shell isolation from the substrate is reported. The process is based on interrupting NW growth and applying a thin spin-on-glass (SOG) layer to the base of the NWs and resuming core-shell NW growth. NW growth occurred in an atmospheric pressure metalorganic vapour phase epitaxy (MOVPE) system with gold nanoparticles used as catalysts for the vapour-liquid-solid growth. It is shown that NW axial core growth and radial shell growth can be resumed after interruption and even exposure to air. The SOG residues and native oxide layer that forms on the NW surface are shown to prevent or perturb resumption of epitaxial NW growth if not removed. Both HF etching and in situ annealing of the air-exposed NWs in the MOVPE were shown to remove the SOG residues and native oxide layer. While both procedures are shown capable of removing the native oxide and enabling resumption of epitaxial NW growth, in situ annealing produced the best results and allowed construction of pristine core-shell NWs. No growth occurred on SOG and it was observed that axial NW growth was more rapid when a SOG layer covered the substrate. The fabricated p-core/n-shell NWs exhibited diode behaviour upon electrical testing. The isolation of the NW shells from the substrate was confirmed by scanning electron microscopy and electrical measurements. The crystal quality of the regrown core-shell NWs was verified with a high resolution transmission electron microscope. The reported technique potentially provides a pathway using MOVPE for scalable and high-throughput production of shell-substrate isolated core-shell NWs on an industrial scale.

  5. Lithography-free shell-substrate isolation for core-shell GaAs nanowires.

    PubMed

    Haggren, Tuomas; Perros, Alexander Pyymaki; Jiang, Hua; Huhtio, Teppo; Kakko, Joona-Pekko; Dhaka, Veer; Kauppinen, Esko; Lipsanen, Harri

    2016-07-01

    A facile and scalable lithography-free technique(5) for the rapid construction of GaAs core-shell nanowires incorporating shell isolation from the substrate is reported. The process is based on interrupting NW growth and applying a thin spin-on-glass (SOG) layer to the base of the NWs and resuming core-shell NW growth. NW growth occurred in an atmospheric pressure metalorganic vapour phase epitaxy (MOVPE) system with gold nanoparticles used as catalysts for the vapour-liquid-solid growth. It is shown that NW axial core growth and radial shell growth can be resumed after interruption and even exposure to air. The SOG residues and native oxide layer that forms on the NW surface are shown to prevent or perturb resumption of epitaxial NW growth if not removed. Both HF etching and in situ annealing of the air-exposed NWs in the MOVPE were shown to remove the SOG residues and native oxide layer. While both procedures are shown capable of removing the native oxide and enabling resumption of epitaxial NW growth, in situ annealing produced the best results and allowed construction of pristine core-shell NWs. No growth occurred on SOG and it was observed that axial NW growth was more rapid when a SOG layer covered the substrate. The fabricated p-core/n-shell NWs exhibited diode behaviour upon electrical testing. The isolation of the NW shells from the substrate was confirmed by scanning electron microscopy and electrical measurements. The crystal quality of the regrown core-shell NWs was verified with a high resolution transmission electron microscope. The reported technique potentially provides a pathway using MOVPE for scalable and high-throughput production of shell-substrate isolated core-shell NWs on an industrial scale. PMID:27242347

  6. Lithography-free shell-substrate isolation for core–shell GaAs nanowires

    NASA Astrophysics Data System (ADS)

    Haggren, Tuomas; Pyymaki Perros, Alexander; Jiang, Hua; Huhtio, Teppo; Kakko, Joona-Pekko; Dhaka, Veer; Kauppinen, Esko; Lipsanen, Harri

    2016-07-01

    A facile and scalable lithography-free technique5 for the rapid construction of GaAs core–shell nanowires incorporating shell isolation from the substrate is reported. The process is based on interrupting NW growth and applying a thin spin-on-glass (SOG) layer to the base of the NWs and resuming core–shell NW growth. NW growth occurred in an atmospheric pressure metalorganic vapour phase epitaxy (MOVPE) system with gold nanoparticles used as catalysts for the vapour‑liquid‑solid growth. It is shown that NW axial core growth and radial shell growth can be resumed after interruption and even exposure to air. The SOG residues and native oxide layer that forms on the NW surface are shown to prevent or perturb resumption of epitaxial NW growth if not removed. Both HF etching and in situ annealing of the air-exposed NWs in the MOVPE were shown to remove the SOG residues and native oxide layer. While both procedures are shown capable of removing the native oxide and enabling resumption of epitaxial NW growth, in situ annealing produced the best results and allowed construction of pristine core–shell NWs. No growth occurred on SOG and it was observed that axial NW growth was more rapid when a SOG layer covered the substrate. The fabricated p-core/n-shell NWs exhibited diode behaviour upon electrical testing. The isolation of the NW shells from the substrate was confirmed by scanning electron microscopy and electrical measurements. The crystal quality of the regrown core–shell NWs was verified with a high resolution transmission electron microscope. The reported technique potentially provides a pathway using MOVPE for scalable and high-throughput production of shell-substrate isolated core–shell NWs on an industrial scale.

  7. Multiple shell fusion targets

    DOEpatents

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

    1975-10-31

    Multiple shell fusion targets for use with electron beam and ion beam implosion systems are described. The multiple shell targets are of the low-power type and use a separate relatively low Z, low density ablator at large radius for the outer shell, which reduces the focusing and power requirements of the implosion system while maintaining reasonable aspect ratios. The targets use a high Z, high density pusher shell placed at a much smaller radius in order to obtain an aspect ratio small enough to protect against fluid instability. Velocity multiplication between these shells further lowers the power requirements. Careful tuning of the power profile and intershell density results in a low entropy implosion which allows breakeven at low powers. For example, with ion beams as a power source, breakeven at 10-20 Terrawatts with 10 MeV alpha particles for imploding a multiple shell target can be accomplished.

  8. Breakup of finite thickness viscous shell microbubbles by ultrasound: A simplified zero-thickness shell model

    PubMed Central

    Hsiao, Chao-Tsung; Chahine, Georges L.

    2013-01-01

    A simplified three-dimensional (3-D) zero-thickness shell model was developed to recover the non-spherical response of thick-shelled encapsulated microbubbles subjected to ultrasound excitation. The model was validated by comparison with previously developed models and was then used to study the mechanism of bubble break-up during non-spherical deformations resulting from the presence of a nearby rigid boundary. The effects of the shell thickness and the bubble standoff distance from the solid wall on the bubble break-up were studied parametrically for a fixed insonification frequency and amplitude. A diagram of bubble shapes versus the normalized shell thickness and wall standoff was derived, and the potential bubble shapes at break-up from reentrant jets were categorized resulting in four distinct zones. PMID:23556560

  9. Imperfection Insensitive Thin Shells

    NASA Astrophysics Data System (ADS)

    Ning, Xin

    The buckling of axially compressed cylindrical shells and externally pressurized spherical shells is extremely sensitive to even very small geometric imperfections. In practice this issue is addressed by either using overly conservative knockdown factors, while keeping perfect axial or spherical symmetry, or adding closely and equally spaced stiffeners on shell surface. The influence of imperfection-sensitivity is mitigated, but the shells designed from these approaches are either too heavy or very expensive and are still sensitive to imperfections. Despite their drawbacks, these approaches have been used for more than half a century. This thesis proposes a novel method to design imperfection-insensitive cylindrical shells subject to axial compression. Instead of following the classical paths, focused on axially symmetric or high-order rotationally symmetric cross-sections, the method in this thesis adopts optimal symmetry-breaking wavy cross-sections (wavy shells). The avoidance of imperfection sensitivity is achieved by searching with an evolutionary algorithm for smooth cross-sectional shapes that maximize the minimum among the buckling loads of geometrically perfect and imperfect wavy shells. It is found that the shells designed through this approach can achieve higher critical stresses and knockdown factors than any previously known monocoque cylindrical shells. It is also found that these shells have superior mass efficiency to almost all previously reported stiffened shells. Experimental studies on a design of composite wavy shell obtained through the proposed method are presented in this thesis. A method of making composite wavy shells and a photogrametry technique of measuring full-field geometric imperfections have been developed. Numerical predictions based on the measured geometric imperfections match remarkably well with the experiments. Experimental results confirm that the wavy shells are not sensitive to imperfections and can carry axial compression

  10. Iridescence color of shells

    NASA Astrophysics Data System (ADS)

    Liu, Yan

    2002-06-01

    Some shells from both salt water and fresh water show the phenomenon of iridescence color. Pearls and mother-of-pearls also display this phenomenon. In the past, the cause of the iridescence color was attributed to interference. A scanning electron microscope (SEM) was used to study the surface structure of the shell of the mollusk Pinctada Margaritifera. There is a groove structure of reflection grating on the surface area in where the iridescence color appears. An optic experiment with a laser obtained a diffraction pattern produced by the reflection grating structure of the shell. The study led to a conclusion that the iridescence color of the shell is caused by diffraction. A SEM image of the shells of an abalone Haliotis Rufescens (red abalone) showed a statistically regularly arranged tile structure that serves as a two-dimensional grating. This grating structure causes the iridescence color of the shell of red abalone. The dominant color of the iridescence of shells is caused by the uneven grating efficiency in the visible wavelength range when a shell functions as a reflection grating. The wavelength of the dominant color should be at or near the wavelength of the maximum efficiency of the grating.

  11. Static cylindrical matter shells

    NASA Astrophysics Data System (ADS)

    Arık, Metin; Delice, Özgür

    2005-08-01

    Static cylindrical shells composed of massive particles arising from matching of two different Levi-Civita space-times are studied for the shell satisfying either an isotropic or an anisotropic equation of state. We find that these solutions satisfy the energy conditions for certain ranges of the parameters.

  12. Nuclear shell evolution

    NASA Astrophysics Data System (ADS)

    Bentley, Ian

    2016-03-01

    The appearance and disappearance of nuclear shells and sub-shells has been at the forefront of recent nuclear theory and experimental efforts. This work extends a previously introduced method of structural analysis and applies it to protons in an attempt to provide a more complete understanding of shell structure in nuclei. Experimental observables including the mean square charge radius, as well as other spectroscopic and mass related quantities have been analyzed for shell structure features. A preliminary analysis using Nilsson coefficient fits of experimental quantities, such as odd mass spectra and B(E2) values, along isotopic chains will be discussed. The goal of this work is to provide a means of predicting shell structure far from stability. This work was supported by the National Science Foundation under Grants PHY1419765 and PHY0822648.

  13. Cohesive Elements for Shells

    NASA Technical Reports Server (NTRS)

    Davila, Carlos G.; Camanho, Pedro P.; Turon, Albert

    2007-01-01

    A cohesive element for shell analysis is presented. The element can be used to simulate the initiation and growth of delaminations between stacked, non-coincident layers of shell elements. The procedure to construct the element accounts for the thickness offset by applying the kinematic relations of shell deformation to transform the stiffness and internal force of a zero-thickness cohesive element such that interfacial continuity between the layers is enforced. The procedure is demonstrated by simulating the response and failure of the Mixed Mode Bending test and a skin-stiffener debond specimen. In addition, it is shown that stacks of shell elements can be used to create effective models to predict the inplane and delamination failure modes of thick components. The results indicate that simple shell models can retain many of the necessary predictive attributes of much more complex 3D models while providing the computational efficiency that is necessary for design.

  14. Method of altering the effective bulk density of solid material and the resulting product

    DOEpatents

    Kool, Lawrence B.; Nolen, Robert L.; Solomon, David E.

    1983-01-01

    A method of adjustably tailoring the effective bulk density of a solid material in which a mixture comprising the solid material, a film-forming polymer and a volatile solvent are sprayed into a drying chamber such that the solvent evaporates and the polymer dries into hollow shells having the solid material captured within the shell walls. Shell density may be varied as a function of solid/polymer concentration, droplet size and drying temperature.

  15. Failure of Viral Shells

    NASA Astrophysics Data System (ADS)

    Klug, William S.; Bruinsma, Robijn F.; Michel, Jean-Philippe; Knobler, Charles M.; Ivanovska, Irena L.; Schmidt, Christoph F.; Wuite, Gijs J. L.

    2006-12-01

    We report a combined theoretical and experimental study of the structural failure of viral shells under mechanical stress. We find that discontinuities in the force-indentation curve associated with failure should appear when the so-called Föppl von Kármán (FvK) number exceeds a critical value. A nanoindentation study of a viral shell subject to a soft-mode instability, where the stiffness of the shell decreases with increasing pH, confirms the predicted onset of failure as a function of the FvK number.

  16. Endoliths in Lithophaga lithophaga shells--Variation in intensity of infestation and species occurrence.

    PubMed

    Peharda, Melita; Calcinai, Barbara; Puljas, Sanja; Golubić, Stjepko; Arapov, Jasna; Thébault, Julien

    2015-07-01

    Pronounced differences with respect to the extent of infestation and the degree of Lithophaga lithophaga shell damage inflicted by euendolithic taxa at two sites in the Adriatic Sea representing different productivity conditions, are described. Shells collected from the eastern part of Kaštela Bay, which is characterized by higher primary productivity, have significantly more shell damage then the shell collected from a site on the outer coast of the island of Čiovo exposed to the oligotrophic Adriatic Sea. The presence of endoliths and their perforations were detected in different layers of the shell, including solidly mineralized parts of the skeleton and within the organic lamellae incorporated into the shell. Phototrophic endoliths were not observed in the specimens. The most serious damage to L. lithophaga shells was the boring clionaid sponge Pione vastifica, which was more common in shells collected from Kaštela. PMID:25982321

  17. Key techniques and applications of adaptive growth method for stiffener layout design of plates and shells

    NASA Astrophysics Data System (ADS)

    Ding, Xiaohong; Ji, Xuerong; Ma, Man; Hou, Jianyun

    2013-11-01

    The application of the adaptive growth method is limited because several key techniques during the design process need manual intervention of designers. Key techniques of the method including the ground structure construction and seed selection are studied, so as to make it possible to improve the effectiveness and applicability of the adaptive growth method in stiffener layout design optimization of plates and shells. Three schemes of ground structures, which are comprised by different shell elements and beam elements, are proposed. It is found that the main stiffener layouts resulted from different ground structures are almost the same, but the ground structure comprised by 8-nodes shell elements and both 3-nodes and 2-nodes beam elements can result in clearest stiffener layout, and has good adaptability and low computational cost. An automatic seed selection approach is proposed, which is based on such selection rules that the seeds should be positioned on where the structural strain energy is great for the minimum compliance problem, and satisfy the dispersancy requirement. The adaptive growth method with the suggested key techniques is integrated into an ANSYS-based program, which provides a design tool for the stiffener layout design optimization of plates and shells. Typical design examples, including plate and shell structures to achieve minimum compliance and maximum bulking stability are illustrated. In addition, as a practical mechanical structural design example, the stiffener layout of an inlet structure for a large-scale electrostatic precipitator is also demonstrated. The design results show that the adaptive growth method integrated with the suggested key techniques can effectively and flexibly deal with stiffener layout design problem for plates and shells with complex geometrical shape and loading conditions to achieve various design objectives, thus it provides a new solution method for engineering structural topology design optimization.

  18. Hollow spherical shell manufacture

    DOEpatents

    O'Holleran, T.P.

    1991-11-26

    A process is disclosed for making a hollow spherical shell of silicate glass composition in which an aqueous suspension of silicate glass particles and an immiscible liquid blowing agent is placed within the hollow spherical cavity of a porous mold. The mold is spun to reduce effective gravity to zero and to center the blowing agent, while being heated so as to vaporize the immiscible liquid and urge the water carrier of the aqueous suspension to migrate into the body of the mold, leaving a green shell compact deposited around the mold cavity. The green shell compact is then removed from the cavity, and is sintered for a time and a temperature sufficient to form a silicate glass shell of substantially homogeneous composition and uniform geometry. 3 figures.

  19. Hollow spherical shell manufacture

    DOEpatents

    O'Holleran, Thomas P.

    1991-01-01

    A process for making a hollow spherical shell of silicate glass composition in which an aqueous suspension of silicate glass particles and an immiscible liquid blowing agent is placed within the hollow spherical cavity of a porous mold. The mold is spun to reduce effective gravity to zero and to center the blowing agent, while being heated so as to vaporize the immiscible liquid and urge the water carrier of the aqueous suspension to migrate into the body of the mold, leaving a green shell compact deposited around the mold cavity. The green shell compact is then removed from the cavity, and is sintered for a time and a temperature sufficient to form a silicate glass shell of substantially homogeneous composition and uniform geometry.

  20. C-Shell Cookbook

    NASA Astrophysics Data System (ADS)

    Currie, Malcolm J.

    This cookbook describes the fundamentals of writing scripts using the UNIX C shell. It shows how to combine Starlink and private applications with shell commands and constructs to create powerful and time-saving tools for performing repetitive jobs, creating data-processing pipelines, and encapsulating useful recipes. The cookbook aims to give practical and reassuring examples to at least get you started without having to consult a UNIX manual. However, it does not offer a comprehensive description of C-shell syntax to prevent you from being overwhelmed or intimidated. The topics covered are: how to run a script, defining shell variables, prompting, arithmetic and string processing, passing information between Starlink applications, obtaining dataset attributes and FITS header information, processing multiple files and filename modification, command-line arguments and options, and loops. There is also a glossary.

  1. Shells and Patterns

    ERIC Educational Resources Information Center

    Sutley, Jane

    2009-01-01

    "Shells and Patterns" was a project the author felt would easily put smiles on the faces of her fifth-graders, and teach them about unity and the use of watercolor pencils as well. It was thrilling to see the excitement in her students as they made their line drawings of shells come to life. For the most part, they quickly got the hang of…

  2. Double shell liner implosions

    SciTech Connect

    Sorokin, S. A.; Chaikovsky, S. A.

    1997-05-05

    Experiments on the double shell liner (DSL) implosions with and without an initial axial magnetic were performed on the SNOP-3 pulse generator (1.1 MA, 100 ns). In implosions of a DSL without an initial axial magnetic field, high radial compressions of the inner shell were observed, as in previous experiments with an initial axial magnetic field. Possible mechanisms for the formation of the initial azimuthal magnetic field are discussed.

  3. Isogeometric phase-field modeling of brittle and ductile fracture in shell structures

    NASA Astrophysics Data System (ADS)

    Ambati, Marreddy; Kiendl, Josef; De Lorenzis, Laura

    2016-08-01

    Phase-field modeling of brittle and ductile fracture is a modern promising approach that enables a unified description of complicated failure processes (including crack initiation, propagation, branching, merging), as well as its efficient numerical treatment [1-4]. In the present work, we apply this approach to model fracture in shell structures, considering both thin and thick shells. For thin shells, we use an isogeometric Kirchhoff-Love shell formulation [5-6], which exploits the high continuity of the isogeometric shape functions in order to avoid rotational degrees of freedom, i.e., the shell geometry is modeled as a surface and its deformation is fully described by the displacements of this surface. For thick shells, we use an isogeometric assumed natural strain (ANS) solid shell formulation [7], i.e., a 3D solid formulation enhanced with the ANS method in order to alleviate geometrical locking effects. According to the discretization of the structural formulations, an isogeometric basis is also used for the phase-field. While the phase-field fracture formulation for solid shells is basically the same as for standard solids, some reformulation is necessary for thin shells, accounting for the interaction of stresses devoted to membrane and bending deformation. We test both formulations on several numerical examples and perform comparisons of the results obtained by the two methods to each other as well as to reference solutions, which confirm the validity and applicability of the presented methods.

  4. Liquid-drop technique for generation of organic glass and metal shells

    SciTech Connect

    Hendricks, C.D.

    1981-12-23

    We have for several years utilized the technique of capillary wave synchronization of the break-up of single and multiple component jets to produce uniform sized liquid drops and solid particles, and hollow liquid and solid shells. The technique has also been used to encapsulate a number of liquids in impermeable spherical shells. Highly uniform glass shells have been made by generating uniform drops of glass forming materials in an aqueous solution, subsequently evaporating the water, and then fusing and blowing the remaining solids in a high temperature vertical tube furnace. Experimental results will be presented and the critical problems in further research in this field will be discussed.

  5. Synthesis of core-shell molecularly imprinted polymer microspheres by precipitation polymerization for the inline molecularly imprinted solid-phase extraction of thiabendazole from citrus fruits and orange juice samples.

    PubMed

    Barahona, Francisco; Turiel, Esther; Cormack, Peter A G; Martín-Esteban, Antonio

    2011-01-01

    In this work, the synthesis of molecularly imprinted polymer microspheres with narrow particle size distributions and core-shell morphology by a two-step precipitation polymerization procedure is described. Polydivinylbenzene (poly DVB-80) core particles were used as seed particles in the production of molecularly imprinted polymer shells by copolymerization of divinylbenzene-80 with methacrylic acid in the presence of thiabendazole (TBZ) and an appropriate porogen. Thereafter, polymer particles were packed into refillable stainless steel HPLC columns used in the development of an inline molecularly imprinted SPE method for the determination of TBZ in citrus fruits and orange juice samples. Under optimized chromatographic conditions, recoveries of TBZ within the range 81.1-106.4%, depending upon the sample, were obtained, with RSDs lower than 10%. This novel method permits the unequivocal determination of TBZ in the samples under study, according to the maximum residue levels allowed within Europe, in less than 20 min and without any need for a clean-up step in the analytical protocol.

  6. Multi-Shell Hollow Nanogels with Responsive Shell Permeability

    NASA Astrophysics Data System (ADS)

    Schmid, Andreas J.; Dubbert, Janine; Rudov, Andrey A.; Pedersen, Jan Skov; Lindner, Peter; Karg, Matthias; Potemkin, Igor I.; Richtering, Walter

    2016-03-01

    We report on hollow shell-shell nanogels with two polymer shells that have different volume phase transition temperatures. By means of small angle neutron scattering (SANS) employing contrast variation and molecular dynamics (MD) simulations we show that hollow shell-shell nanocontainers are ideal systems for controlled drug delivery: The temperature responsive swelling of the inner shell controls the uptake and release, while the thermoresponsive swelling of the outer shell controls the size of the void and the colloidal stability. At temperatures between 32 °C < T < 42 °C, the hollow nanocontainers provide a significant void, which is even larger than the initial core size of the template, and they possess a high colloidal stability due to the steric stabilization of the swollen outer shell. Computer simulations showed, that temperature induced switching of the permeability of the inner shell allows for the encapsulation in and release of molecules from the cavity.

  7. Multi-Shell Hollow Nanogels with Responsive Shell Permeability.

    PubMed

    Schmid, Andreas J; Dubbert, Janine; Rudov, Andrey A; Pedersen, Jan Skov; Lindner, Peter; Karg, Matthias; Potemkin, Igor I; Richtering, Walter

    2016-03-17

    We report on hollow shell-shell nanogels with two polymer shells that have different volume phase transition temperatures. By means of small angle neutron scattering (SANS) employing contrast variation and molecular dynamics (MD) simulations we show that hollow shell-shell nanocontainers are ideal systems for controlled drug delivery: The temperature responsive swelling of the inner shell controls the uptake and release, while the thermoresponsive swelling of the outer shell controls the size of the void and the colloidal stability. At temperatures between 32 °C < T < 42 °C, the hollow nanocontainers provide a significant void, which is even larger than the initial core size of the template, and they possess a high colloidal stability due to the steric stabilization of the swollen outer shell. Computer simulations showed, that temperature induced switching of the permeability of the inner shell allows for the encapsulation in and release of molecules from the cavity.

  8. Multi-Shell Hollow Nanogels with Responsive Shell Permeability

    PubMed Central

    Schmid, Andreas J.; Dubbert, Janine; Rudov, Andrey A.; Pedersen, Jan Skov; Lindner, Peter; Karg, Matthias; Potemkin, Igor I.; Richtering, Walter

    2016-01-01

    We report on hollow shell-shell nanogels with two polymer shells that have different volume phase transition temperatures. By means of small angle neutron scattering (SANS) employing contrast variation and molecular dynamics (MD) simulations we show that hollow shell-shell nanocontainers are ideal systems for controlled drug delivery: The temperature responsive swelling of the inner shell controls the uptake and release, while the thermoresponsive swelling of the outer shell controls the size of the void and the colloidal stability. At temperatures between 32 °C < T < 42 °C, the hollow nanocontainers provide a significant void, which is even larger than the initial core size of the template, and they possess a high colloidal stability due to the steric stabilization of the swollen outer shell. Computer simulations showed, that temperature induced switching of the permeability of the inner shell allows for the encapsulation in and release of molecules from the cavity. PMID:26984478

  9. Rapid magnetic-mediated solid-phase extraction and pre-concentration of selected endocrine disrupting chemicals in natural waters by poly(divinylbenzene-co-methacrylic acid) coated Fe3O4 core-shell magnetite microspheres for their liquid chromatography-tandem mass spectrometry determination.

    PubMed

    Li, Qingling; Lam, Michael H W; Wu, Rudolf S S; Jiang, Biwang

    2010-02-19

    A new Fe(3)O(4)/poly(divinylbenzene-co-methacrylic acid) core-shell magnetite microspheric material have been successfully developed as magnetic-mediated solid-phase extraction micro-particle sorbent in dispersion mode (MM-SPE-MP) for the determination of selected estrogenic endocrine disrupting chemicals (EDCs), namely: estrone (E1), 17beta-estradiol (E2), estriol (E3), 17alpha-ethynylestradiol (EE2) and bisphenol-A (BPA), in natural water, via quantification by HPLC tandem mass spectrometry. The magnetite Fe(3)O(4) core of this MM-SPE-MP sorbent was fabricated by a solvothermal approach and the thin layer of amphipolar poly(divinylbenzene-co-methacrylic acid) (pDVB-MAA) coating was established via suspension polymerization. The resultant core-shell MM-SPE-MP sorbent material was characterized by electron microscopy, X-ray diffraction and Fourier-transformed infrared spectroscopy. Particle size distribution of the core-shell microspheres was within the range 300-700 nm in diameter and the thickness of the pDVB-MAA coating was ca. 10nm. This magnetite microspheric material can be easily dispersed in aqueous samples and retrieved by the application of external magnetic field via a small piece of permanent magnet. The MM-SPE-MP process for the selected estrogenic EDCs involved the dispersion of the core-shell microspheric sorbent in water samples with sonication, followed by magnetic aided retrieval of the sorbent and solvent (methanol) desorption of extracted EDCs for LC-MS/MS analysis. Partition equilibrium for all the selected EDCs onto this MM-SPE-MP sorbent was achieved within 15 min. Recoveries of the EDCs were in ranges of 56-111%. Analytes with smaller K(OW) value showed relatively lower recovery (and relatively longer equilibration time for partitioning). Method detection limits achieved were found to be 1-36 pg ml(-1) (n=3), while the repeatability was 6-34% (p<0.05, n=3). This work demonstrates the usefulness of MM-SPE-MP in the rapid and highly sensitive

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

    PubMed

    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. PMID:22545710

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

    PubMed

    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.

  12. An immersed-shell method for modelling fluid–structure interactions

    PubMed Central

    Viré, A.; Xiang, J.; Pain, C. C.

    2015-01-01

    The paper presents a novel method for numerically modelling fluid–structure interactions. The method consists of solving the fluid-dynamics equations on an extended domain, where the computational mesh covers both fluid and solid structures. The fluid and solid velocities are relaxed to one another through a penalty force. The latter acts on a thin shell surrounding the solid structures. Additionally, the shell is represented on the extended domain by a non-zero shell-concentration field, which is obtained by conservatively mapping the shell mesh onto the extended mesh. The paper outlines the theory underpinning this novel method, referred to as the immersed-shell approach. It also shows how the coupling between a fluid- and a structural-dynamics solver is achieved. At this stage, results are shown for cases of fundamental interest. PMID:25583857

  13. SiS2 in circumstellar shells

    NASA Astrophysics Data System (ADS)

    Goebel, J. H.

    1993-10-01

    Solid state SiS2 is proposed as the material responsible for the recently discovered 21 micrometer emission feature that is observed in the carbon-rich circumstellar shells of certain protoplanetary nebulae. Sulfurized SiC, or SiS2 mantles on grains of either SiC or a:C-H are discussed as possible forms for which no spectroscopic laboratory observations yet exist. The identification with a relatively minor species and required special abundance ratios are consistent with the low incidence rate that the 21 micrometer feature presents in the population of carbon rich objects. It is also consistent with the lack of a good correlation between the 21 micrometer feature and the other solid-state spectroscopic features that have been observed in protoplanetaries that would be expected if the feature arose from molecules composed of H, C, N, and O. SiS2 condensate is consistent with the circumstellar shell temperature range, TCS approximately equal to or less than 150 K, at which the feature appears, and the available mass of SiS2, MSiS2 approx. = 5 x 10-6 solar mass, that is possible in the circumstellar shell.

  14. Switching closed-shell to open-shell phenalenyl: toward designing electroactive materials.

    PubMed

    Pariyar, Anand; Vijaykumar, Gonela; Bhunia, Mrinal; Dey, Suman Kr; Singh, Santosh K; Kurungot, Sreekumar; Mandal, Swadhin K

    2015-05-13

    Open-shell phenalenyl chemistry started more than half a century back, and the first solid-state phenalenyl radical was realized only 15 years ago highlighting the synthetic challenges associated in stabilizing carbon-based radical chemistry, though it has great promise as building blocks for molecular electronics and multifunctional materials. Alternatively, stable closed-shell phenalenyl has tremendous potential as it can be utilized to create an in situ open-shell state by external spin injection. In the present study, we have designed a closed-shell phenalenyl-based iron(III) complex, Fe(III)(PLY)3 (PLY-H = 9-hydroxyphenalenone) displaying an excellent electrocatalytic property as cathode material for one compartment membraneless H2O2 fuel cell. The power density output of Fe(III)(PLY)3 is nearly 15-fold higher than the structurally related model compound Fe(III)(acac)3 (acac = acetylacetonate) and nearly 140-fold higher than an earlier reported mononuclear Fe(III) complex, Fe(III)(Pc)Cl (Pc = pthalocyaninate), highlighting the role of switchable closed-shell phenalenyl moiety for electron-transfer process in designing electroactive materials.

  15. Fabrication of diamond shells

    DOEpatents

    Hamza, Alex V.; Biener, Juergen; Wild, Christoph; Woerner, Eckhard

    2016-11-01

    A novel method for fabricating diamond shells is introduced. The fabrication of such shells is a multi-step process, which involves diamond chemical vapor deposition on predetermined mandrels followed by polishing, microfabrication of holes, and removal of the mandrel by an etch process. The resultant shells of the present invention can be configured with a surface roughness at the nanometer level (e.g., on the order of down to about 10 nm RMS) on a mm length scale, and exhibit excellent hardness/strength, and good transparency in the both the infra-red and visible. Specifically, a novel process is disclosed herein, which allows coating of spherical substrates with optical-quality diamond films or nanocrystalline diamond films.

  16. Shell Biorefinery: Dream or Reality?

    PubMed

    Chen, Xi; Yang, Huiying; Yan, Ning

    2016-09-12

    Shell biorefinery, referring to the fractionation of crustacean shells into their major components and the transformation of each component into value-added chemicals and materials, has attracted growing attention in recent years. Since the large quantities of waste shells remain underexploited, their valorization can potentially bring both ecological and economic benefits. This Review provides an overview of the current status of shell biorefinery. It first describes the structural features of crustacean shells, including their composition and their interactions. Then, various fractionation methods for the shells are introduced. The last section is dedicated to the valorization of chitin and its derivatives for chemicals, porous carbon materials and functional polymers.

  17. Shell Biorefinery: Dream or Reality?

    PubMed

    Chen, Xi; Yang, Huiying; Yan, Ning

    2016-09-12

    Shell biorefinery, referring to the fractionation of crustacean shells into their major components and the transformation of each component into value-added chemicals and materials, has attracted growing attention in recent years. Since the large quantities of waste shells remain underexploited, their valorization can potentially bring both ecological and economic benefits. This Review provides an overview of the current status of shell biorefinery. It first describes the structural features of crustacean shells, including their composition and their interactions. Then, various fractionation methods for the shells are introduced. The last section is dedicated to the valorization of chitin and its derivatives for chemicals, porous carbon materials and functional polymers. PMID:27484462

  18. Oyster shell conveyor used to lift shells from the dock ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Oyster shell conveyor used to lift shells from the dock into the receiving room housed in the 1965 concrete block addition. - J.C. Lore Oyster House, 14430 Solomons Island Road, Solomons, Calvert County, MD

  19. Dynamics of a suspension of interacting yolk-shell particles

    SciTech Connect

    Sánchez Díaz, L. E.; Cortes-Morales, E. C.; Li, X.; Chen, Wei-Ren; Medina-Noyola, M.

    2014-12-01

    In this work we study the self-diusion properties of a liquid of hollow spherical particles (shells) bearing a smaller solid sphere in their interior (yolks). We model this system using purely repulsive hard-body interactions between all (shell and yolk) particles, but assume the presence of a background ideal solvent such that all the particles execute free Brownian motion between collisions, characterized by short-time self-diusion coecients D0 s for the shells and D0 y for the yolks. Using a softened version of these interparticle potentials we perform Brownian dynamics simulations to determine the mean squared displacement and intermediate scattering function of the yolk-shell complex. These results can be understood in terms of a set of eective Langevin equations for the N interacting shell particles, pre-averaged over the yolks' degrees of freedom, from which an approximate self-consistent description of the simulated self-diusion properties can be derived. Here we compare the theoretical and simulated results between them, and with the results for the same system in the absence of yolks. We nd that the yolks, which have no eect on the shell-shell static structure, in uence the dynamic properties in a predictable manner, fully captured by the theory.

  20. Dynamics of a suspension of interacting yolk-shell particles

    DOE PAGES

    Sánchez Díaz, L. E.; Cortes-Morales, E. C.; Li, X.; Chen, Wei-Ren; Medina-Noyola, M.

    2014-12-01

    In this work we study the self-diusion properties of a liquid of hollow spherical particles (shells) bearing a smaller solid sphere in their interior (yolks). We model this system using purely repulsive hard-body interactions between all (shell and yolk) particles, but assume the presence of a background ideal solvent such that all the particles execute free Brownian motion between collisions, characterized by short-time self-diusion coecients D0 s for the shells and D0 y for the yolks. Using a softened version of these interparticle potentials we perform Brownian dynamics simulations to determine the mean squared displacement and intermediate scattering function ofmore » the yolk-shell complex. These results can be understood in terms of a set of eective Langevin equations for the N interacting shell particles, pre-averaged over the yolks' degrees of freedom, from which an approximate self-consistent description of the simulated self-diusion properties can be derived. Here we compare the theoretical and simulated results between them, and with the results for the same system in the absence of yolks. We nd that the yolks, which have no eect on the shell-shell static structure, in uence the dynamic properties in a predictable manner, fully captured by the theory.« less

  1. Agreement, Shells, and Focus.

    ERIC Educational Resources Information Center

    Simpson, Andrew; Wu, Zoe

    2002-01-01

    Reconsiders development and licensing of agreement as a syntactic projection and argues for a productive developmental relation between agreement and the category of focus. Suggests that focus projections are initially selected by a variety of functional heads with real semantic content, then, over time decays into a simple concord shell. Upon…

  2. Snail Shell Science.

    ERIC Educational Resources Information Center

    Matthews, Catherine

    1992-01-01

    Presents three inquiry-based lessons to develop the science process skills of observation, identification, and classification. Activities use whelk eggs and snail shells as the focus of the students' inquiries. Provides a list of 19 facts about whelks and snails. (MDH)

  3. Shell Higher Olefins Process.

    ERIC Educational Resources Information Center

    Lutz, E. F.

    1986-01-01

    Shows how olefin isomerization and the exotic olefin metathesis reaction can be harnessed in industrial processes. Indicates that the Shell Higher Olefins Process makes use of organometallic catalysts to manufacture alpha-olefins and internal carbon-11 through carbon-14 alkenes in a flexible fashion that can be adjusted to market needs. (JN)

  4. Shell Creek Summers

    ERIC Educational Resources Information Center

    Seier, Mark; Goedeken, Suzy

    2005-01-01

    In 2002 Shell Creek Watershed Improvement Group turned to the Newman Grove Public Schools' science department to help educate the public on water quality in the watershed and to establish a monitoring system that would be used to improve surface and groundwater quality in the creek's watershed. Nebraska Department of Environmental Quality provided…

  5. Solid phase extraction using magnetic core mesoporous shell microspheres with C18-modified interior pore-walls for residue analysis of cephalosporins in milk by LC-MS/MS.

    PubMed

    Liu, Xiaodan; Yu, Yingjia; Zhao, Meiyan; Zhang, Haiying; Li, Yan; Duan, Gengli

    2014-05-01

    A fast and effective extraction method has been developed for measuring the residue of cephalosporins (cefalexin, cefazolin, cefoperazone) in milk by using magnetic core-mesoporous shell microspheres with C18-functionalized interior pore-walls (C18-Fe3O4@mSiO2) as adsorbent. With no need for any protein precipitation procedure, the cephalosporins were directly adsorbed onto the C18-Fe3O4@mSiO2 microspheres through hydrophobic interaction with C18-groups (Octadecyl functional groups) functionalized in the interior walls of mesopore channels while the abundant proteins in milk sample were excluded out of the channel due to the size exclusion effect. Thereafter, the cephalosporins-absorbed C18-Fe3O4@mSiO2 microspheres were rapidly isolated by placing a magnet, and followed by liquid chromatography-tandem mass spectrometry analysis after eluted by methanol. Various parameters which could affect the extraction performance were optimised. The newly developed extraction method was successfully applied in determination of cephalosporin residues in milk samples, offering a valuable alternative to simplify and speed up the sample preparation step.

  6. Stability of charged thin shells

    SciTech Connect

    Eiroa, Ernesto F.; Simeone, Claudio

    2011-05-15

    In this article we study the mechanical stability of spherically symmetric thin shells with charge, in Einstein-Maxwell and Einstein-Born-Infeld theories. We analyze linearized perturbations preserving the symmetry, for shells around vacuum and shells surrounding noncharged black holes.

  7. 7 CFR 51.2002 - Split shell.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Split shell. 51.2002 Section 51.2002 Agriculture... Standards for Grades of Filberts in the Shell 1 Definitions § 51.2002 Split shell. Split shell means a shell... of the shell, measured in the direction of the crack....

  8. Engineering bacterial microcompartment shells: chimeric shell proteins and chimeric carboxysome shells.

    PubMed

    Cai, Fei; Sutter, Markus; Bernstein, Susan L; Kinney, James N; Kerfeld, Cheryl A

    2015-04-17

    Bacterial microcompartments (BMCs) are self-assembling organelles composed entirely of protein. Depending on the enzymes they encapsulate, BMCs function in either inorganic carbon fixation (carboxysomes) or organic carbon utilization (metabolosomes). The hallmark feature of all BMCs is a selectively permeable shell formed by multiple paralogous proteins, each proposed to confer specific flux characteristics. Gene clusters encoding diverse BMCs are distributed broadly across bacterial phyla, providing a rich variety of building blocks with a predicted range of permeability properties. In theory, shell permeability can be engineered by modifying residues flanking the pores (symmetry axes) of hexameric shell proteins or by combining shell proteins from different types of BMCs into chimeric shells. We undertook both approaches to altering shell properties using the carboxysome as a model system. There are two types of carboxysomes, α and β. In both, the predominant shell protein(s) contain a single copy of the BMC domain (pfam00936), but they are significantly different in primary structure. Indeed, phylogenetic analysis shows that the two types of carboxysome shell proteins are more similar to their counterparts in metabolosomes than to each other. We solved high resolution crystal structures of the major shell proteins, CsoS1 and CcmK2, and the presumed minor shell protein CcmK4, representing both types of cyanobacterial carboxysomes and then tested the interchangeability. The in vivo study presented here confirms that both engineering pores to mimic those of other shell proteins and the construction of chimeric shells is feasible.

  9. Relativistic shell model calculations

    NASA Astrophysics Data System (ADS)

    Furnstahl, R. J.

    1986-06-01

    Shell model calculations are discussed in the context of a relativistic model of nuclear structure based on renormalizable quantum field theories of mesons and baryons (quantum hadrodynamics). The relativistic Hartree approximation to the full field theory, with parameters determined from bulk properties of nuclear matter, predicts a shell structure in finite nuclei. Particle-hole excitations in finite nuclei are described in an RPA calculation based on this QHD ground state. The particle-hole interaction is prescribed by the Hartree ground state, with no additional parameters. Meson retardation is neglected in deriving the RPA equations, but it is found to have negligible effects on low-lying states. The full Dirac matrix structure is maintained throughout the calculation; no nonrelativistic reductions are made. Despite sensitive cancellations in the ground state calculation, reasonable excitation spectra are obtained for light nuclei. The effects of including charged mesons, problems with heavy nuclei, and prospects for improved and extended calculations are discussed.

  10. Spectroscopy of Mn atoms isolated in solid {sup 4}He

    SciTech Connect

    Moroshkin, P. Lebedev, V.; Weis, A.

    2014-06-07

    We present an experimental study of the laser-induced luminescence spectra of Mn atoms in solid helium matrices. We observe transitions of the valence electron and of inner-shell electrons. We find that the Mn-He interaction perturbs the inner-shell transitions to a lesser extent than the valence-electron transitions. The observed lineshapes of the inner-shell transitions of Mn are similar to those of an inner-shell transition in Ba studied earlier. At the same time, they are more strongly perturbed than the corresponding transitions in Au and Cu under the same conditions. We suggest a qualitative explanation of these observations based on the atomic bubble model. Our results also suggest that the inner-shell transitions of Mn in solid He are more strongly perturbed than the same lines of Mn isolated in solid Ar or Kr matrices.

  11. A computer program for anisotropic shallow-shell finite elements using symbolic integration

    NASA Technical Reports Server (NTRS)

    Andersen, C. M.; Bowen, J. T.

    1976-01-01

    A FORTRAN computer program for anisotropic shallow-shell finite elements with variable curvature is described. A listing of the program is presented together with printed output for a sample case. Computation times and central memory requirements are given for several different elements. The program is based on a stiffness (displacement) finite-element model in which the fundamental unknowns consist of both the displacement and the rotation components of the reference surface of the shell. Two triangular and four quadrilateral elements are implemented in the program. The triangular elements have 6 or 10 nodes, and the quadrilateral elements have 4 or 8 nodes. Two of the quadrilateral elements have internal degrees of freedom associated with displacement modes which vanish along the edges of the elements (bubble modes). The triangular elements and the remaining two quadrilateral elements do not have bubble modes. The output from the program consists of arrays corresponding to the stiffness, the geometric stiffness, the consistent mass, and the consistent load matrices for individual elements. The integrals required for the generation of these arrays are evaluated by using symbolic (or analytic) integration in conjunction with certain group-theoretic techniques. The analytic expressions for the integrals are exact and were developed using the symbolic and algebraic manipulation language.

  12. Liquid drop technique for generation of organic glass and metal shells

    NASA Technical Reports Server (NTRS)

    Hendricks, C. D.

    1982-01-01

    It was found that liquid drop techniques are very useful in several diverse areas. For producing very uniform metallic, organic, inorganic and, on particular, glassy shells, the liquid jet method is the most reproducible and exceptionally useful of all the techniques studied. The technique of capillary wave synchronization of the break-up of single and multiple component jets was utilized to produce uniform sized liquid drops and solid particles, and hollow liquid and solid shells. The technique was also used to encapsulate a number of liquids in impermeable spherical shells. Highly uniform glass shells were made by generating uniform drops of glass forming materials in an aqueous solution, subsequently evaporating the water, and then fusing and blowing the remaining solids in a high temperature vertical tube furnace. Experimental results are presented and the critical problems in further research in this field are discussed.

  13. Making Solid Geometry Solid.

    ERIC Educational Resources Information Center

    Hartz, Viggo

    1981-01-01

    Allowing students to use a polystyrene cutter to fashion their own three-dimensional models is suggested as a means of allowing individuals to experience problems and develop ideas related to solid geometry. A list of ideas that can lead to mathematical discovery is provided. (MP)

  14. Em Response of a Conductive, Permeable Spherical Shell

    2005-10-24

    This code calculates the spectral response of conductive, permeable, shell in a conductive whole space using a closed form solution. The source is either a uniform field (approximately valid when the size of the sphere is small compared to the distance to the source) or the field of dipole (and by superposition, the field of a finite loop). The code is particularly useful in showing that the typical UXO (usually shells), the response is significantlymore » different at intermediate to late times compared to solids of the same materials.« less

  15. Natural melting within a spherical shell

    NASA Technical Reports Server (NTRS)

    Bahrami, Parviz A.

    1990-01-01

    Fundamental heat transfer experiments were performed on the melting of a phase change medium in a spherical shell. Free expansion of the medium into a void space within the sphere was permitted. A step function temperature jump on the outer shell wall was imposed and the timewise evolution of the melting process and the position of the solid-liquid interface was photographically recorded. Numerical integration of the interface position data yielded information about the melted mass and the energy of melting. It was found that the rate of melting and the heat transfer were significantly affected by the movement of the solid medium to the base of the sphere due to gravity. The energy transfer associated with melting was substantially higher than that predicted by the conduction model. Furthermore, the radio of the measured values of sensible energy in the liquid melt to the energy of melting were nearly proportional to the Stefan number. The experimental results are in agreement with a theory set forth in an earlier paper.

  16. Characterization of the pigmented shell-forming proteome of the common grove snail Cepaea nemoralis

    PubMed Central

    2014-01-01

    Background With a diversity of pigmented shell morphotypes governed by Mendelian patterns of inheritance, the common grove snail, Cepaea nemoralis, has served as a model for evolutionary biologists and population geneticists for decades. Surprisingly, the molecular mechanisms by which C. nemoralis generates this pigmented shelled diversity, and the degree of evolutionary conservation present between molluscan shell-forming proteomes, remain unknown. Results Here, using next generation sequencing and high throughput proteomics, we identify and characterize the major proteinaceous components of the C. nemoralis shell, the first shell-proteome for a pulmonate mollusc. The recent availability of several marine molluscan shell-proteomes, and the dataset we report here, allow us to identify 59 evolutionarily conserved and novel shell-forming proteins. While the C. nemoralis dataset is dominated by proteins that share little to no similarity with proteins in public databases, almost half of it shares similarity with proteins present in other molluscan shells. In addition, we could not find any indication that a protein (or class of proteins) is directly associated with shell pigmentation in C. nemoralis. This is in contrast to the only other partially characterized molluscan-shell pigmentation mechanism employed by the tropical abalone Haliotis asinina. Conclusions The unique pulmonate shell-forming proteome that we report here reveals an abundance of both mollusc-specific and pulmonate-specific proteins, suggesting that novel coding sequences, and/or the extensive divergence of these sequences from ancestral sequences, supported the innovation of new shell types within the Conchifera. In addition, we report here the first evidence that molluscs use independently evolved mechanisms to pigment their shells. This proteome provides a solid foundation from which further studies aimed at the functional characterization of these shell-forming proteins can be conducted. PMID

  17. The structure of circumstellar shells

    NASA Technical Reports Server (NTRS)

    Fix, John D.

    1993-01-01

    This document provides a report on research activities carried out with the support of NASA grant NAG 5-1174, the Structure of Circumstellar Shells, funded under the Astrophysics Data Program. The research carried out with the support of this grant is a study of the properties of circumstellar dust shells for which spectra are available through IRAS low resolution spectrometry (LRS). This research consisted of the development and application of models of axisymmetric circumstellar shells and a preliminary survey of the applicability of neural nets for analysis of the IRAS LRS spectra of circumstellar dust shells.

  18. Automated shell theory for rotating structures (ASTROS)

    NASA Technical Reports Server (NTRS)

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

    1971-01-01

    A computer program for analyzing axisymmetric shells with inertial forces caused by rotation about the shell axis is developed by revising the STARS II shell program. The basic capabilities of the STARS II shell program, such as the treatment of the branched shells, stiffened wall construction, and thermal gradients, are retained.

  19. 7 CFR 51.2289 - Shell.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Shell. 51.2289 Section 51.2289 Agriculture Regulations... Standards for Shelled English Walnuts (Juglans Regia) Definitions § 51.2289 Shell. Shell means the outer shell and/or the woody partition from between the halves of the kernel, and any fragments of either....

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

    SciTech Connect

    Heiles, C.

    1984-08-01

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

  1. Three dimensional sound transmission through poroelastic cylindrical shells in the presence of subsonic flow

    NASA Astrophysics Data System (ADS)

    Talebitooti, R.; Daneshjou, K.; Kornokar, M.

    2016-02-01

    This paper proposes an extension of the full method to investigate sound transmission through poroelastic cylindrical shell. The "extended full method" is presented based on Biot theory with considering the 3-D wave propagation in a cylindrical shell. Contrary to previous methods, it could be applicable for both poroelastic cylindrical shells and double-walled cylindrical shells lined with poroelastic materials with an excellent accuracy. In the extended full method, the well-known Helmholtz decomposition is used to obtain the displacement fields, solid stresses and the fluid pressure. In order to verify the results of the poroelastic cylindrical shell the porosity goes into zero with eliminating the fluid phase of the poroelastic material. Thus, the results are compared with those of TLs for isotropic shell with high accuracy. The results also indicate that enhancing the porosity of the poroelastic cylindrical shells efficiently leads into decreasing the TL. It is also designated that with doubling the thickness of the poroelastic shell, the TL is improved about 6 dB in a broad-band frequency. Also, the present method is investigated for the case of a double-walled cylindrical shell composed of isotropic skins and poroelastic core. The first-order shear deformation theory is applied to modeling the isotropic shells. The results indicate that presented method is more accurate than simplified method, particularly in the case of small radius cylindrical shells. Moreover, the results indicate that with increasing the radius of the shell, the double-walled cylindrical shell behaves in a same trend as a double-walled flat plate.

  2. Biomineralisation in Mollusc shells

    NASA Astrophysics Data System (ADS)

    Dauphin, Y.; Cuif, J. P.; Salomé, M.; Williams, C. T.

    2009-04-01

    The main components of Mollusc shells are carbonate minerals: calcite and aragonite. ACC is present in larval stages. Calcite and aragonite can be secreted simultaneously by the mantle. Despite the small number of varieties, the arrangement of the mineral components is diverse, and dependant upon the taxonomy. They are also associated with organic components much more diverse, the diversity of which reflects the large taxonomic diversity. From TGA analyses, the organic content (water included) is high (>5% in some layers). The biomineralisation process is not a passive precipitation process, but is strongly controlled by the organism. The biological-genetic control is shown by the constancy of the arrangement of the layers, the mineralogy and the microstructure in a given species. Microstructural units (i.e. tablets, prisms etc.) have shapes that do not occur in non-biogenic counterparts. Nacreous tablets, for example, are flattened on their crystallographic c axis, which is normally the axis of maximum growth rate for non-biogenic aragonite. Morever, their inner structure is species-specific: the arrangements of nacreous tablets in Gastropoda - Cephalopoda, and in Bivalvia differ, and the inner arrangement of the nacreous tablets is different in ectocochlear and endocochlear Cephalopoda. The organic-mineral ratios also differ in the various layers of a shell. Differences in chemical composition also demonstrates the biological-genetic control: for example, aragonite has a low Sr content unknown in non-biogenic samples; two aragonitic layers in a shell have different Sr and Mg contents, S is higher in calcitic layers. Decalcification releases soluble (SOM) and insoluble (IOM) organic components. Insoluble components form the main part of the intercrystalline membranes, and contain proteins, polysaccharides and lipids. Soluble phases are present within the crystals and the intercrystalline membranes. These phases are composed of more or less glycosylated proteins

  3. NIKE3D: an implicit, finite-deformation, finite element code for analyzing the static and dynamic response of three-dimensional solids

    SciTech Connect

    Hallquist, J.O.

    1981-01-01

    A user's manual is provided for NIKE3D, a fully implicit three-dimensional finite element code for analyzing the large deformation static and dynamic response of inelastic solids. A contact-impact algorithm permits gaps and sliding along material interfaces. By a specialization of this algorithm, such interfaces can be rigidly tied to admit variable zoning without the need of transition regions. Spatial discretization is achieved by the use of 8-node constant pressure solid elements. Bandwidth minimization is optional. Post-processors for NIKE3D include GRAPE for plotting deformed shapes and stress contours and DYNAP for plotting time histories.

  4. Summary compilation of shell element performance versus formulation.

    SciTech Connect

    Heinstein, Martin Wilhelm; Hales, Jason Dean; Breivik, Nicole L.; Key, Samuel W.

    2011-07-01

    This document compares the finite element shell formulations in the Sierra Solid Mechanics code. These are finite elements either currently in the Sierra simulation codes Presto and Adagio, or expected to be added to them in time. The list of elements are divided into traditional two-dimensional, plane stress shell finite elements, and three-dimensional solid finite elements that contain either modifications or additional terms designed to represent the bending stiffness expected to be found in shell formulations. These particular finite elements are formulated for finite deformation and inelastic material response, and, as such, are not based on some of the elegant formulations that can be found in an elastic, infinitesimal finite element setting. Each shell element is subjected to a series of 12 verification and validation test problems. The underlying purpose of the tests here is to identify the quality of both the spatially discrete finite element gradient operator and the spatially discrete finite element divergence operator. If the derivation of the finite element is proper, the discrete divergence operator is the transpose of the discrete gradient operator. An overall summary is provided from which one can rank, at least in an average sense, how well the individual formulations can be expected to perform in applications encountered year in and year out. A letter grade has been assigned albeit sometimes subjectively for each shell element and each test problem result. The number of A's, B's, C's, et cetera assigned have been totaled, and a grade point average (GPA) has been computed, based on a 4.0-system. These grades, combined with a comparison between the test problems and the application problem, can be used to guide an analyst to select the element with the best shell formulation.

  5. Fabrication of iron (III) oxide doped polystyrene shells

    NASA Astrophysics Data System (ADS)

    Cai, Pei-Jun; Tang, Yong-Jian; Zhang, Lin; Du, Kai; Feng, Chang-Gen

    2004-03-01

    A type of iron (III) oxide doped plastic shell used for inertial confinement fusion experiments has been fabricated by emulsion techniques. Three different phases of solution (W1, O, and W2) are used for the fabrication process. The W1 phase is a 1 wt % of sodium lauryl sulfate in water. This W1 phase solution is mixed with a 3 wt % Fe2O3-polystyrene (PS) solution in benzene-dichloroethane (O phase) while stirring. The resulting emulsion (W1/O) is poured into a 3 wt % aqueous polyvinyl alcohol solution (W2 phase) while stirring. The resulting emulsion (W1/O/W2) is then heated to evaporate benzene and dichloroethane, and thus a solid Fe2O3-PS shell is formed. The diameter and wall thickness of the shells range from 150 to 500 μm and 5 to 15 μm, respectively. The average surface roughness of the shells is 40 nm, similar to that of the usual PS shells. .

  6. Solids Accumulation Scouting Studies

    SciTech Connect

    Duignan, M. R.; Steeper, T. J.; Steimke, J. L.

    2012-09-26

    The objective of Solids Accumulation activities was to perform scaled testing to understand the behavior of remaining solids in a Double Shell Tank (DST), specifically AW-105, at Hanford during multiple fill, mix, and transfer operations. It is important to know if fissionable materials can concentrate when waste is transferred from staging tanks prior to feeding waste treatment plants. Specifically, there is a concern that large, dense particles containing plutonium could accumulate in poorly mixed regions of a blend tank heel for tanks that employ mixing jet pumps. At the request of the DOE Hanford Tank Operations Contractor, Washington River Protection Solutions, the Engineering Development Laboratory of the Savannah River National Laboratory performed a scouting study in a 1/22-scale model of a waste staging tank to investigate this concern and to develop measurement techniques that could be applied in a more extensive study at a larger scale. Simulated waste tank solids: Gibbsite, Zirconia, Sand, and Stainless Steel, with stainless steel particles representing the heavier particles, e.g., plutonium, and supernatant were charged to the test tank and rotating liquid jets were used to mix most of the solids while the simulant was pumped out. Subsequently, the volume and shape of the mounds of residual solids and the spatial concentration profiles for the surrogate for heavier particles were measured. Several techniques were developed and equipment designed to accomplish the measurements needed and they included: 1. Magnetic particle separator to remove simulant stainless steel solids. A device was designed and built to capture these solids, which represent the heavier solids during a waste transfer from a staging tank. 2. Photographic equipment to determine the volume of the solids mounds. The mounds were photographed as they were exposed at different tank waste levels to develop a composite of topographical areas. 3. Laser rangefinders to determine the volume of

  7. Glass shell manufacturing in space

    NASA Technical Reports Server (NTRS)

    Downs, R. L.; Ebner, M. A.; Nolen, R. L., Jr.

    1981-01-01

    Highly-uniform, hollow glass spheres (shells), which are used for inertial confinement fusion targets, were formed from metal-organic gel powder feedstock in a vertical furnace. As a result of the rapid pyrolysis caused by the furnace, the gel is transformed to a shell in five distinct stages: (a) surface closure of the porous gel; (b) generation of a closed-cell foam structure in the gel; (c) spheridization of the gel and further expansion of the foam; (d) coalescence of the closed-cell foam to a single-void shell; and (e) fining of the glass shell. The heat transfer from the furnace to the falling gel particle was modeled to determine the effective heating rate of the gel. The model predicts the temperature history for a particle as a function of mass, dimensions, specific heat, and absorptance as well as furnace temperature profile and thermal conductivity of the furnace gas. A model was developed that predicts the gravity-induced degradation of shell concentricity in falling molten shells as a function of shell characteristics and time.

  8. Crack problems in cylindrical and spherical shells

    NASA Technical Reports Server (NTRS)

    Erdogan, F.

    1976-01-01

    Standard plate or shell theories were used as a starting point to study the fracture problems in thin-walled cylindrical and spherical shells, assuming that the plane of the crack is perpendicular to the surface of the sheet. Since recent studies have shown that local shell curvatures may have a rather considerable effect on the stress intensity factor, the crack problem was considered in conjunction with a shell rather than a plate theory. The material was assumed to be isotropic and homogeneous, so that approximate solutions may be obtained by approximating the local shell crack geometry with an ideal shell which has a solution, namely a spherical shell with a meridional crack, a cylindrical shell with a circumferential crack, or a cylindrical shell with an axial crack. A method of solution for the specially orthotropic shells containing a crack was described; symmetric and skew-symmetric problems are considered in cylindrical shells with an axial crack.

  9. A simple low temperature synthesis route for ZnO-MgO core-shell nanowires.

    PubMed

    Plank, N O V; Snaith, H J; Ducati, C; Bendall, J S; Schmidt-Mende, L; Welland, M E

    2008-11-19

    We report a hydrothermal synthesis method for MgO shell coatings directly onto the surface of ZnO nanowire arrays. The entire process can be carried out below 100 °C. The MgO shells are produced by the addition of 10 mM magnesium nitrate with 0.2 M sodium hydroxide in water, resulting in a shell thickness of up to 8 nm, verified by high resolution transmission electron microscopy. The viability of the MgO layer as a functional element of optoelectronic devices was tested on solid-state organic hole-transporter based dye-sensitized solar cells. Incorporation of the MgO shell into the solar cell resulted in substantive efficiency improvements of over 400% in comparison to the pristine ZnO nanowire based photovoltaics, indicating that electrons can efficiently tunnel through the 'insulating' MgO shell.

  10. Optimum rotationally symmetric shells for flywheel rotors

    DOEpatents

    Blake, Henry W.

    2000-01-01

    A flywheel rim support formed from two shell halves. Each of the shell halves has a disc connected to the central shaft. A first shell element connects to the disc at an interface. A second shell element connects to the first shell element. The second shell element has a plurality of meridional slits. A cylindrical shell element connects to the second shell element. The cylindrical shell element connects to the inner surface of the flywheel rim. A flywheel rim support having a disc connected an outer diameter of a shaft. Two optimally shaped shell elements connect to the optimally shaped disc at an interface. The interface defines a discontinuity in a meridional slope of said support. A cylindrical shell element connects to the two shell elements. The cylindrical shell element has an outer surface for connecting to the inner surface of the flywheel rim. A flywheel rim casing includes an annular shell connected to the central shaft. The annular shell connects to the flywheel rim. A composite shell surrounds the shaft, annular shell and flywheel rim.

  11. MicroShell Minimalist Shell for Xilinx Microprocessors

    NASA Technical Reports Server (NTRS)

    Werne, Thomas A.

    2011-01-01

    MicroShell is a lightweight shell environment for engineers and software developers working with embedded microprocessors in Xilinx FPGAs. (MicroShell has also been successfully ported to run on ARM Cortex-M1 microprocessors in Actel ProASIC3 FPGAs, but without project-integration support.) Micro Shell decreases the time spent performing initial tests of field-programmable gate array (FPGA) designs, simplifies running customizable one-time-only experiments, and provides a familiar-feeling command-line interface. The program comes with a collection of useful functions and enables the designer to add an unlimited number of custom commands, which are callable from the command-line. The commands are parameterizable (using the C-based command-line parameter idiom), so the designer can use one function to exercise hardware with different values. Also, since many hardware peripherals instantiated in FPGAs have reasonably simple register-mapped I/O interfaces, the engineer can edit and view hardware parameter settings at any time without stopping the processor. MicroShell comes with a set of support scripts that interface seamlessly with Xilinx's EDK tool. Adding an instance of MicroShell to a project is as simple as marking a check box in a library configuration dialog box and specifying a software project directory. The support scripts then examine the hardware design, build design-specific functions, conditionally include processor-specific functions, and complete the compilation process. For code-size constrained designs, most of the stock functionality can be excluded from the compiled library. When all of the configurable options are removed from the binary, MicroShell has an unoptimized memory footprint of about 4.8 kB and a size-optimized footprint of about 2.3 kB. Since MicroShell allows unfettered access to all processor-accessible memory locations, it is possible to perform live patching on a running system. This can be useful, for instance, if a bug is

  12. Solid propellants.

    NASA Technical Reports Server (NTRS)

    Marsh, H. E., Jr.; Hutchison, J. J.

    1972-01-01

    The basic principles underlying propulsion by rocket motor are examined together with the configuration of a solid propellant motor. Solid propellants and their preparation are discussed, giving attention to homogeneous propellants, composite propellants, energetic considerations in choosing a solid propellant, the processing of composite propellants, and some examples of new developments. The performance of solid propellants is investigated, taking into account characteristics velocity, the specific impulse, and performance calculations. Aspects of propellant development considered include nonperformance requirements for solid propellants, the approach to development, propellant mechanical properties, and future trends.

  13. Investigation of polymer-shelled microbubble motions in acoustophoresis.

    PubMed

    Kothapalli, Satya V V N; Wiklund, Martin; Janerot-Sjoberg, Birgitta; Paradossi, Gaio; Grishenkov, Dmitry

    2016-08-01

    The objective of this paper is to explore the trajectory motion of microsize (typically smaller than a red blood cell) encapsulated polymer-shelled gas bubbles propelled by radiation force in an acoustic standing-wave field and to compare the corresponding movements of solid polymer microbeads. The experimental setup consists of a microfluidic chip coupled to a piezoelectric crystal (PZT) with a resonance frequency of about 2.8MHz. The microfluidic channel consists of a rectangular chamber with a width, w, corresponding to one wavelength of the ultrasound standing wave. It creates one full wave ultrasound of a standing-wave pattern with two pressure nodes at w/4 and 3w/4 and three antinodes at 0, w/2, and w. The peak-to-peak amplitude of the electrical potential over the PZT was varied between 1 and 10V. The study is limited to no-flow condition. From Gor'kov's potential equation, the acoustic contrast factor, Φ, for the polymer-shelled microbubbles was calculated to about -60.7. Experimental results demonstrate that the polymer-shelled microbubbles are translated and accumulated at the pressure antinode planes. This trajectory motion of polymer-shelled microbubbles toward the pressure antinode plane is similar to what has been described for other acoustic contrast particles with a negative Φ. First, primary radiation forces dragged the polymer-shelled microbubbles into proximity with each other at the pressure antinode planes. Then, primary and secondary radiation forces caused them to quickly aggregate at different spots along the channel. The relocation time for polymer-shelled microbubbles was 40 times shorter than that for polymer microbeads, and in contrast to polymer microbeads, the polymer-shelled microbubbles were actuated even at driving voltages (proportional to radiation forces) as low as 1V. In short, the polymer-shelled microbubbles demonstrate the behavior attributed to the negative acoustic contrast factor particles and thus can be trapped at the

  14. Investigation of polymer-shelled microbubble motions in acoustophoresis.

    PubMed

    Kothapalli, Satya V V N; Wiklund, Martin; Janerot-Sjoberg, Birgitta; Paradossi, Gaio; Grishenkov, Dmitry

    2016-08-01

    The objective of this paper is to explore the trajectory motion of microsize (typically smaller than a red blood cell) encapsulated polymer-shelled gas bubbles propelled by radiation force in an acoustic standing-wave field and to compare the corresponding movements of solid polymer microbeads. The experimental setup consists of a microfluidic chip coupled to a piezoelectric crystal (PZT) with a resonance frequency of about 2.8MHz. The microfluidic channel consists of a rectangular chamber with a width, w, corresponding to one wavelength of the ultrasound standing wave. It creates one full wave ultrasound of a standing-wave pattern with two pressure nodes at w/4 and 3w/4 and three antinodes at 0, w/2, and w. The peak-to-peak amplitude of the electrical potential over the PZT was varied between 1 and 10V. The study is limited to no-flow condition. From Gor'kov's potential equation, the acoustic contrast factor, Φ, for the polymer-shelled microbubbles was calculated to about -60.7. Experimental results demonstrate that the polymer-shelled microbubbles are translated and accumulated at the pressure antinode planes. This trajectory motion of polymer-shelled microbubbles toward the pressure antinode plane is similar to what has been described for other acoustic contrast particles with a negative Φ. First, primary radiation forces dragged the polymer-shelled microbubbles into proximity with each other at the pressure antinode planes. Then, primary and secondary radiation forces caused them to quickly aggregate at different spots along the channel. The relocation time for polymer-shelled microbubbles was 40 times shorter than that for polymer microbeads, and in contrast to polymer microbeads, the polymer-shelled microbubbles were actuated even at driving voltages (proportional to radiation forces) as low as 1V. In short, the polymer-shelled microbubbles demonstrate the behavior attributed to the negative acoustic contrast factor particles and thus can be trapped at the

  15. Insulative laser shell coupler

    DOEpatents

    Arnold, Phillip A.; Anderson, Andrew T.; Alger, Terry W.

    1994-01-01

    A segmented coaxial laser shell assembly having at least two water jacket sections, two pairs of interconnection half rings, a dialectric break ring, and a pair of threaded ring sections. Each water jacket section with an inner tubular section that defines an inner laser cavity with water paths adjacent to at least a portion of the exterior of the inner tubular section, and mating faces at the end of the water jacket section through which the inner laser cavity opens and which defines at least one water port therethrough in communication with the water jackets. The water paths also define in their external surface a circumferential notch set back from and in close proximity to the mating face. The dielectric break ring has selected thickness and is placed between, and in coaxial alignment with, the mating faces of two of the adjacent water jacket sections. The break ring also defines an inner laser cavity of the same size and shape as the inner laser cavity of the water jacket sections and at least one water passage through the break ring to communicate with at least one water port through the mating faces of the water jacket sections.

  16. Insulative laser shell coupler

    DOEpatents

    Arnold, P.A.; Anderson, A.T.; Alger, T.W.

    1994-09-20

    A segmented coaxial laser shell assembly having at least two water jacket sections, two pairs of interconnection half rings, a dielectric break ring, and a pair of threaded ring sections is disclosed. Each water jacket section with an inner tubular section that defines an inner laser cavity with water paths adjacent to at least a portion of the exterior of the inner tubular section, and mating faces at the end of the water jacket section through which the inner laser cavity opens and which defines at least one water port therethrough in communication with the water jackets. The water paths also define in their external surface a circumferential notch set back from and in close proximity to the mating face. The dielectric break ring has selected thickness and is placed between, and in coaxial alignment with, the mating faces of two of the adjacent water jacket sections. The break ring also defines an inner laser cavity of the same size and shape as the inner laser cavity of the water jacket sections and at least one water passage through the break ring to communicate with at least one water port through the mating faces of the water jacket sections. 4 figs.

  17. Stellar Populations of Shell Galaxies

    NASA Astrophysics Data System (ADS)

    Carlsten, Scott; Zenteno, Alfredo

    2016-01-01

    We present a study of the inner (out to ˜1 effective radius) stellar populations in a sample of 9 shell galaxies. We derive stellar population parameters from long slit spectra by both analyzing the Lick indices of the galaxies and by fitting high resolution SSP model spectra to the full galaxy spectra. The results from the two methods agree reasonably well. We find the presence of young stellar populations in several of the galaxies, implying recent star formation and allowing us to speculate on the age of the shells. Analyzing the metallicity gradients in our sample, we find an average metallicity gradient of -0.16±0.10 dex/decade in radius. Finally, we compare this with galaxy evolution models to try to constrain the merging history of shell galaxies. We argue that our galaxies likely have undergone major mergers in their past but it is unclear whether the shells formed from these events or from separate minor mergers.

  18. Collapsing thin shells with rotation

    NASA Astrophysics Data System (ADS)

    Delsate, Térence; Rocha, Jorge V.; Santarelli, Raphael

    2014-06-01

    We construct exact solutions describing the motion of rotating thin shells in a fully backreacted five-dimensional rotating black hole spacetime. The radial equation of motion follows from the Darmois-Israel junction conditions, where both interior and exterior geometries are taken to be equal angular momenta Myers-Perry solutions. We show that rotation generates anisotropic pressures and momentum along the shell. Gravitational collapse scenarios including rotation are analyzed and a new class of stationary solutions is introduced. Energy conditions for the anisotropic matter shell are briefly discussed. We find that the weak energy condition is not violated for the collapse scenario where the shell starts at rest from infinity, nor for the new class of stationary solutions in anti-de Sitter. We further prove that the cosmic censorship conjecture is always satisfied in our setup.

  19. 7 CFR 996.19 - Shelled peanuts.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 8 2012-01-01 2012-01-01 false Shelled peanuts. 996.19 Section 996.19 Agriculture... STANDARDS FOR DOMESTIC AND IMPORTED PEANUTS MARKETED IN THE UNITED STATES Definitions § 996.19 Shelled peanuts. Shelled peanuts means the kernels or portions of kernels of peanuts after the shells are removed....

  20. 7 CFR 996.19 - Shelled peanuts.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 8 2014-01-01 2014-01-01 false Shelled peanuts. 996.19 Section 996.19 Agriculture... STANDARDS FOR DOMESTIC AND IMPORTED PEANUTS MARKETED IN THE UNITED STATES Definitions § 996.19 Shelled peanuts. Shelled peanuts means the kernels or portions of kernels of peanuts after the shells are removed....

  1. 7 CFR 996.19 - Shelled peanuts.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 8 2013-01-01 2013-01-01 false Shelled peanuts. 996.19 Section 996.19 Agriculture... STANDARDS FOR DOMESTIC AND IMPORTED PEANUTS MARKETED IN THE UNITED STATES Definitions § 996.19 Shelled peanuts. Shelled peanuts means the kernels or portions of kernels of peanuts after the shells are removed....

  2. Slowly rotating thin shell gravastars

    NASA Astrophysics Data System (ADS)

    Uchikata, Nami; Yoshida, Shijun

    2016-01-01

    We construct the solutions of slowly rotating gravastars with a thin shell. In the zero-rotation limit, we consider the gravastar composed of a de Sitter core, a thin shell, and Schwarzschild exterior spacetime. The rotational effects are treated as small axisymmetric and stationary perturbations. The perturbed internal and external spacetimes are matched with a uniformly rotating thin shell. We assume that the angular velocity of the thin shell, Ω, is much smaller than the Keplerian frequency of the nonrotating gravastar, {{{Ω }}}{{k}}. The solutions within an accuracy up to the second order of {{Ω }}/{{{Ω }}}{{k}} are obtained. The thin shell matter is assumed to be described by a perfect fluid and to satisfy the dominant energy condition in the zero-rotation limit. In this study, we assume that the equation of state for perturbations is the same as that of the unperturbed solution. The spherically symmetric component of the energy density perturbations, δ {σ }0, is assumed to vanish independently of the rotation rate. Based on these assumptions, we obtain many numerical solutions and investigate properties of the rotational corrections to the structure of the thin shell gravastar.

  3. Comparison of aragonitic molluscan shell proteins.

    PubMed

    Furuhashi, Takeshi; Miksik, Ivan; Smrz, Miloslav; Germann, Bettina; Nebija, Dashnor; Lachmann, Bodo; Noe, Christian

    2010-02-01

    Acidic macromolecules, as a nucleation factor for mollusc shell formation, are a major focus of research. It remains unclear, however, whether acidic macromolecules are present only in calcified shell organic matrices, and which acidic macromolecules are crucial for the nucleation process by binding to chitin as structural components. To clarify these questions, we applied 2D gel electrophoresis and amino acid analysis to soluble shell organic matrices from nacre shell, non-nacre aragonitic shell and non-calcified squid shells. The 2D gel electrophoresis results showed that the acidity of soluble proteins differs even between nacre shells, and some nacre (Haliotis gigantea) showed a basic protein migration pattern. Non-calcified shells also contained some moderately acidic proteins. The results did not support the correlation between the acidity of soluble shell proteins and shell structure.

  4. A 4-node assumed-stress hybrid shell element with rotational degrees of freedom

    NASA Technical Reports Server (NTRS)

    Aminpour, Mohammad A.

    1990-01-01

    An assumed-stress hybrid/mixed 4-node quadrilateral shell element is introduced that alleviates most of the deficiencies associated with such elements. The formulation of the element is based on the assumed-stress hybrid/mixed method using the Hellinger-Reissner variational principle. The membrane part of the element has 12 degrees of freedom including rotational or drilling degrees of freedom at the nodes. The bending part of the element also has 12 degrees of freedom. The bending part of the element uses the Reissner-Mindlin plate theory which takes into account the transverse shear contributions. The element formulation is derived from an 8-node isoparametric element. This process is accomplished by assuming quadratic variations for both in-plane and out-of-plane displacement fields and linear variations for both in-plane and out-of-plane rotation fields along the edges of the element. In addition, the degrees of freedom at midside nodes are approximated in terms of the degrees of freedom at corner nodes. During this process the rotational degrees of freedom at the corner nodes enter into the formulation of the element. The stress field are expressed in the element natural-coordinate system such that the element remains invariant with respect to node numbering.

  5. Direct formulation of a 4-node hybrid shell element with rotational degrees of freedom

    NASA Technical Reports Server (NTRS)

    Aminpour, Mohammad A.

    1990-01-01

    A simple 4-node assumed-stress hybrid quadrilateral shell element with rotational or drilling degrees of freedom is formulated. The element formulation is based directly on a 4-node element. This direct formulation requires fewer computations than a similar element that is derived from an internal 8-node isoparametric element in which the midside degrees of freedom are eliminated in favor of rotational degree of freedom at the corner nodes. The formulation is based on the principle of minimum complementary energy. The membrane part of the element has 12 degrees of freedom including rotational degrees of freedom. The bending part of the element also has 12 degrees of freedom. The bending part of the quadratic variations for both in-plane and out-of-plane displacement fields and linear variations for both in-plane and out-of-plane rotation fields are assumed along the edges of the element. The element Cartesian-coordinate system is chosen such as to make the stress field invariant with respect to node numbering. The membrane part of the stress field is based on a 9-parameter equilibrating stress field, while the bending part is based on a 13-parameter equilibrating stress field. The element passes the patch test, is nearly insensitive to mesh distortion, does not lock, possesses the desirable invariance properties, has no spurious modes, and produces accurate and reliable results.

  6. An assumed-stress hybrid 4-node shell element with drilling degrees of freedom

    NASA Technical Reports Server (NTRS)

    Aminpour, M. A.

    1992-01-01

    An assumed-stress hybrid/mixed 4-node quadrilateral shell element is introduced that alleviates most of the deficiencies associated with such elements. The formulation of the element is based on the assumed-stress hybrid/mixed method using the Hellinger-Reissner variational principle. The membrane part of the element has 12 degrees of freedom including rotational or 'drilling' degrees of freedom at the nodes. The bending part of the element also has 12 degrees of freedom. The bending part of the element uses the Reissner-Mindlin plate theory which takes into account the transverse shear contributions. The element formulation is derived from an 8-node isoparametric element by expressing the midside displacement degrees of freedom in terms of displacement and rotational degrees of freedom at corner nodes. The element passes the patch test, is nearly insensitive to mesh distortion, does not 'lock', possesses the desirable invariance properties, has no hidden spurious modes, and for the majority of test cases used in this paper produces more accurate results than the other elements employed herein for comparison.

  7. Mass of Perfect Fluid Black Shells

    NASA Astrophysics Data System (ADS)

    Zloshchastiev, Konstantin G.

    The spherically symmetric singular perfect fluid shells are considered when their radii are equal to the event horizon (the black shells). We study their observable masses, depending at least on the three parameters, viz. the square speed of sound in the shell, instantaneous radial velocity of the shell at a moment when it reaches the horizon, and integration constant related to surface mass density. We discuss the features of black shells depending on the equation of state.

  8. Solid lubricants

    NASA Technical Reports Server (NTRS)

    Sliney, Harold E.

    1991-01-01

    The state of knowledge of solid lubricants is reviewed. The results of research on solid lubricants from the 1940's to the present are presented from a historical perspective. Emphasis is placed largely, but not exclusively, on work performed at NASA Lewis Research Center with a natural focus on aerospace applications. However, because of the generic nature of the research, the information presented in this review is applicable to most areas where solid lubricant technology is useful.

  9. Ethanol Gas Detection Using a Yolk-Shell (Core-Shell) α-Fe2O3 Nanospheres as Sensing Material.

    PubMed

    Wang, LiLi; Lou, Zheng; Deng, Jianan; Zhang, Rui; Zhang, Tong

    2015-06-17

    Three-dimensional (3D) nanostructures of α-Fe2O3 materials, including both hollow sphere-shaped and yolk-shell (core-shell)-shaped, have been successfully synthesized via an environmentally friendly hydrothermal approach. By expertly adjusting the reaction time, the solid, hollow, and yolk-shell shaped α-Fe2O3 can be selectively synthesized. Yolk-shell α-Fe2O3 nanospheres display outer diameters of 350 nm, and the interstitial hollow spaces layer is intimately sandwiched between the inner and outer shell of α-Fe2O3 nanostructures. The possible growth mechanism of the yolk-shell nanostructure is proposed. The results showed that the well-defined bilayer interface effectively enhanced the sensing performance of the α-Fe2O3 nanostructures (i.e., yolk-shell α-Fe2O3@α-Fe2O3), owing predominantly to the unique nanostructure, thus facilitated the transport rate and augmented the adsorption quantity of the target gas molecule under gas detection.

  10. Gasification of carbonaceous solids

    DOEpatents

    Coates, Ralph L.

    1976-10-26

    A process and apparatus for converting coal and other carbonaceous solids to an intermediate heating value fuel gas or to a synthesis gas. A stream of entrained pulverized coal is fed into the combustion stage of a three-stage gasifier along with a mixture of oxygen and steam at selected pressure and temperature. The products of the combustion stage pass into the second or quench stage where they are partially cooled and further reacted with water and/or steam. Ash is solidified into small particles and the formation of soot is suppressed by water/steam injections in the quench stage. The design of the quench stage prevents slag from solidifying on the walls. The products from the quench stage pass directly into a heat recovery stage where the products pass through the tube, or tubes, of a single-pass, shell and tube heat exchanger and steam is generated on the shell side and utilized for steam feed requirements of the process.

  11. Numerical Investigation of Shell Formation in Thin Slab Casting of Funnel-Type Mold

    NASA Astrophysics Data System (ADS)

    Vakhrushev, A.; Wu, M.; Ludwig, A.; Tang, Y.; Hackl, G.; Nitzl, G.

    2014-06-01

    The key issue for modeling thin slab casting (TSC) process is to consider the evolution of the solid shell including fully solidified strand and partially solidified dendritic mushy zone, which strongly interacts with the turbulent flow and in the meantime is subject to continuous deformation due to the funnel-type mold. Here an enthalpy-based mixture solidification model that considers turbulent flow [Prescott and Incropera, ASME HTD, 1994, vol. 280, pp. 59-69] is employed and further enhanced by including the motion of the solidifying and deforming solid shell. The motion of the solid phase is calculated with an incompressible rigid viscoplastic model on the basis of an assumed moving boundary velocity condition. In the first part, a 2D benchmark is simulated to mimic the solidification and motion of the solid shell. The importance of numerical treatment of the advection of latent heat in the deforming solid shell (mushy zone) is specially addressed, and some interesting phenomena of interaction between the turbulent flow and the growing mushy zone are presented. In the second part, an example of 3D TSC is presented to demonstrate the model suitability. Finally, techniques for the improvement of calculation accuracy and computation efficiency as well as experimental evaluations are also discussed.

  12. User's manuals for DYNA3D and DYNAP: nonlinear dynamic analysis of solids in three dimensions

    SciTech Connect

    Hallquist, J.O.

    1981-07-01

    This report provides a user's manual for DYNA3D, an explicit three-dimensional finite element code for analyzing the large deformation dynamic response of inelastic solids. A contact-impact algorithm permits gaps and sliding along material interfaces. By a specialization of this algorithm, such interfaces can be rigidly tied to admit variable zoning without the need of transition regions. Spatial discretization is achieved by the use of 8-node solid elements, and the equations-of-motion are integrated by the central difference method. Post-processors for DYNA3D include GRAPE for plotting deformed shapes and stress contours and DYNAP for plotting time histories. A user's manual for DYNAP is also provided in this report.

  13. Foam shell project: Progress report

    SciTech Connect

    Overturf, G.; Reibold, B.; Cook, B.; Schroen-Carey, D.

    1994-03-25

    The authors report on their work to produce a foam shell target for two possible applications: (1) as liquid-layered cryogenic target on Omega Upgrade, and (2) as a back-up design for the NIF. This target consists of a roughly 1 mm diameter and 100 {mu}m thick spherical low-density foam shell surrounding a central void. The foam will be slightly overfilled with liquid D{sub 2} or DT, the overfilled excess being symmetrically distributed on the inside of the shell and supported by thermal gradient techniques. The outside of the foam is overcoated with full density polymer which must be topologically smooth. The technology for manufacturing this style of foam shell involves microencapsulation techniques and has been developed by the Japanese at ILE. Their goal is to determine whether this technology can be successfully adapted to meet US ICF objectives. To this end a program of foam shell development has been initiated at LLNL in collaboration with both the General Atomics DOE Target Fabrication Contract Corporation and the Target Fabrication Group at LLE.

  14. Physical quality and composition of retail shell eggs.

    PubMed

    Jones, D R; Musgrove, M T; Anderson, K E; Thesmar, H S

    2010-03-01

    There are a number of specialty shell eggs available to consumers in the US retail market. A survey consisting of white and brown large shell eggs with various production and nutritional differences (traditional, cage-free, free-roaming, pasteurized, nutritionally enhanced, and fertile) was conducted to determine if physical quality and compositional differences exist. Identical brands of eggs were purchased from the same retail outlets on 3 occasions (replicates) in a single city. The average range of time from processing to purchase for all eggs was 7.67 to 25.33 d, with traditional white eggs in retail having the shortest time. Haugh unit values ranged from 66.67 (cage-free, docosahexaenoic acid, and n-3 enhanced) to 84.42 (traditional white). Albumen height followed a similar pattern. Egg weight was greater for brown eggs (61.12 vs. 58.85 g). Brown eggs also had greater static compression shell strength than white eggs (4,130.61 vs. 3,690.31 g force). Vitelline membrane strength was greatest for traditional brown eggs (2.24 g force). Percentage of total solids and crude fat was greatest in the cage-free, n-3-enhanced white eggs (25.07 and 11.71%, respectively). Although significant differences were found between white and brown shell eggs and production methods, average values for quality attributes varied without one egg type consistently maintaining the highest or lowest values.

  15. Shell-NASA Vibration-Based Damage Characterization

    NASA Technical Reports Server (NTRS)

    Rollins, John M.

    2014-01-01

    This article describes collaborative research between Shell International Exploration and Production (IE&P) scientists and ISAG personnel to investigate the feasibility of ultrasonic-based characterization of spacecraft tile damage for in-space inspection applications. The approach was proposed by Shell personnel in a Shell-NASA "speed-matching" session in early 2011 after ISAG personnel described challenges inherent in the inspection of MMOD damage deep within spacecraft thermal protection system (TPS) tiles. The approach leveraged Shell's relevant sensor and analytical expertise. The research addressed the difficulties associated with producing 3D models of MMOD damage cavities under the surface of a TPS tile, given that simple image-based sensing is constrained by line of sight through entry holes that have diameters considerably smaller than the underlying damage cavities. Damage cavity characterization is needed as part of a vehicle inspection and risk reduction capability for long-duration, human-flown space missions. It was hoped that cavity characterization could be accomplished through the use of ultrasonic techniques that allow for signal penetration through solid material.

  16. Washing of the AW-101 entrained solids

    SciTech Connect

    GJ Lumetta

    2000-03-31

    BNFL Inc. (BNFL) is under contract with the US Department of Energy, River Protection Project (DOE-RPP) to design, construct, and operate facilities for treating wastes stored in the single-shell and double-shell tanks at the Hanford Site, Richland, Washington. The DOE-BNFL RPP contract identifies two feeds to the waste treatment plant: (1) primarily liquid low-activity waste (LAW) consisting of less than 2 wt% entrained solids and (2) high-level waste (HLW) consisting of 10 to 200 g/L solids slurry. This report describes the results of a test conducted by Battelle to assess the effects of inhibited water washing on the composition of the entrained solids in the diluted AW-101 low-activity waste (LAW) sample. The objective of this work was to gather data on the solubility of the AW-101 entrained solids in 0.01 M NaOH, so that BNFL can evaluate whether these solids require caustic leaching. The work was conducted according to test plan BNFL-TP-29953-9, Rev. 0, LAW Entrained Solids Water Wash and Caustic Leach Testing. The test went according to plan, with no deviations from the test plan. Based on the results of the 0.01 M NaOH washing, a decision was made by BNFL to not proceed with the caustic leaching test. The composition of the washed solids was such that caustic leaching would not result in significant reduction in the immobilized HLW volume.

  17. Contaminant exposures at the 4H shell mounds in the Santa Barbara Channel.

    PubMed

    Phillips, Charles R; Salazar, Michael H; Salazar, Sandra M; Snyder, Barry J

    2006-12-01

    exhibit clear spatial gradients with distance from the shell mounds. Despite a number of storm events during the mussel exposures, maximum currents were 34 cm s(-1) and unlikely to erode materials from the shell mounds. Thus, Ba distributions in bottom sediments probably were due to episodic disturbance such as platform removal or trawling rather than ongoing erosion and dispersion of shell mound solids by near-bottom currents. These results suggest that, in the absence of physical disturbances, contaminants are expected to remain sequestered in the shell mounds.

  18. Contaminant exposures at the 4H shell mounds in the Santa Barbara Channel.

    PubMed

    Phillips, Charles R; Salazar, Michael H; Salazar, Sandra M; Snyder, Barry J

    2006-12-01

    exhibit clear spatial gradients with distance from the shell mounds. Despite a number of storm events during the mussel exposures, maximum currents were 34 cm s(-1) and unlikely to erode materials from the shell mounds. Thus, Ba distributions in bottom sediments probably were due to episodic disturbance such as platform removal or trawling rather than ongoing erosion and dispersion of shell mound solids by near-bottom currents. These results suggest that, in the absence of physical disturbances, contaminants are expected to remain sequestered in the shell mounds. PMID:16919301

  19. Dominant thermogravimetric signatures of lignin in cashew shell as compared to cashew shell cake.

    PubMed

    Gangil, Sandip

    2014-03-01

    Dominant thermogravimetric signatures related to lignin were observed in cashew shell as compared to these signatures in cashew shell cake. The phenomenon of weakening of lignin from cashew shell to cashew shell cake was explained on the basis of changes in the activation energies. The pertinent temperature regimes responsible for the release of different constituents of both the bio-materials were identified and compared. The activation energies of cashew shell and cashew shell cake were compared using Kissinger-Akahira-Sunose method. Thermogravimetric profiling of cashew shell and cashew shell cake indicated that these were different kinds of bio-materials.

  20. Diverse melting modes and structural collapse of hollow bimetallic core-shell nanoparticles: a perspective from molecular dynamics simulations.

    PubMed

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

    2014-11-14

    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.

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

    PubMed Central

    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

  2. Chemical Analysis Of Beryllium Shells

    SciTech Connect

    Gunther, J; Cook, R

    2005-11-17

    There is a need to understand the level of high-Z impurities in Beryllium shells prepared by sputter coating. The Ignition Point Design Requirements state the following: ''Except for allowed ingredients, as listed in the ablator composition entries, the ablator material in all layers shall contain sufficiently low impurity levels that the sum over all impurities of atom fraction*Z{sup 2} shall be less than or equal to 0.2''. This is a tight specification that requires careful materials analysis. Early in the first quarter of FY06, we undertook a study of Be shell impurities via ICP-MS{sup 2} and determined that the impurity levels in the sputtered shells are very close to the specification.

  3. Shell model Monte Carlo methods

    SciTech Connect

    Koonin, S.E.; Dean, D.J.

    1996-10-01

    We review quantum Monte Carlo methods for dealing with large shell model problems. These methods reduce the imaginary-time many-body evolution operator to a coherent superposition of one-body evolutions in fluctuating one-body fields; resultant path integral is evaluated stochastically. We first discuss the motivation, formalism, and implementation of such Shell Model Monte Carlo methods. There then follows a sampler of results and insights obtained from a number of applications. These include the ground state and thermal properties of pf-shell nuclei, thermal behavior of {gamma}-soft nuclei, and calculation of double beta-decay matrix elements. Finally, prospects for further progress in such calculations are discussed. 87 refs.

  4. Shell may expand detergent alcohols

    SciTech Connect

    1996-10-23

    Shell Chemical is studying plans to expand detergent alcohols capacity in the US, CW has learned. The company is considering adding capacity for about 80 million lbs/year. If the project is approved, it would be implemented at the company`s Geismar, LA site. Shell will make a final decision on whether to proceed with the project within six months. It has been rumored to be considering a capacity addition as a result of tightening supply of natural and synthetic detergent alcohols.

  5. On Closed Shells in Nuclei

    DOE R&D Accomplishments Database

    Mayer, M. G.

    1948-02-01

    It has been suggested in the past that special numbers of neutrons or protons in the nucleus form a particularly stable configuration.{sup1} The complete evidence for this has never been summarized, nor is it generally recognized how convincing this evidence is. That 20 neutrons or protons (Ca{sup40}) form a closed shell is predicted by the Hartree model. A number of calculations support this fact.{sup2} These considerations will not be repeated here. In this paper, the experimental facts indicating a particular stability of shells of 50 and 82 protons and of 50, 82, and 126 neutrons will be listed.

  6. Hollow ruthenium nanoparticles with small dimensions derived from Ni@Ru core@shell structure: synthesis and enhanced catalytic dehydrogenation of ammonia borane.

    PubMed

    Chen, Guozhu; Desinan, Stefano; Rosei, Renzo; Rosei, Federico; Ma, Dongling

    2012-08-18

    Hollow Ru nanoparticles with ~14 nm diameter and ~2 nm shell thickness are reported for the first time, by removal of Ni from the delicately designed Ni@Ru core@shell NPs. Such hollow Ru NPs exhibit enhanced catalytic activity in the dehydrogenation of ammonia borane with respect to solid ones. PMID:22773309

  7. A Shell/3D Modeling Technique for the Analysis of Delaminated Composite Laminates

    NASA Technical Reports Server (NTRS)

    Krueger, Ronald; OBrien, T. Kevin

    2000-01-01

    A shell/3D modeling technique was developed for which a local solid finite element model is used only in the immediate vicinity of the delamination front. The goal was to combine the accuracy of the full three-dimensional solution with the computational efficiency of a shell finite element model. Multi-point constraints provided a kinematically compatible interface between the local 3D model and the global structural model which has been meshed with shell finite elements. Double Cantilever Beam, End Notched Flexure, and Single Leg Bending specimens were analyzed first using full 3D finite element models to obtain reference solutions. Mixed mode strain energy release rate distributions were computed using the virtual crack closure technique. The analyses were repeated using the shell/3D technique to study the feasibility for pure mode I, mode II and mixed mode I/II cases. Specimens with a unidirectional layup and with a multidirectional layup were simulated. For a local 3D model, extending to a minimum of about three specimen thicknesses on either side of the delamination front, the results were in good agreement with mixed mode strain energy release rates obtained from computations where the entire specimen had been modeled with solid elements. For large built-up composite structures the shell/3D modeling technique offers a great potential for reducing the model size, since only a relatively small section in the vicinity of the delamination front needs to be modeled with solid elements.

  8. Engineering of Hollow Core-Shell Interlinked Carbon Spheres for Highly Stable Lithium-Sulfur Batteries.

    PubMed

    Sun, Qiang; He, Bin; Zhang, Xiang-Qian; Lu, An-Hui

    2015-08-25

    We report engineered hollow core-shell interlinked carbon spheres that consist of a mesoporous shell, a hollow void, and an anchored carbon core and are expected to be ideal sulfur hosts for overcoming the shortage of Li-S batteries. The hollow core-shell interlinked carbon spheres were obtained through solution synthesis of polymer spheres followed by a pyrolysis process that occurred in the hermetical silica shell. During the pyrolysis, the polymer sphere was transformed into the carbon core and the carbonaceous volatiles were self-deposited on the silica shell due to the blocking effect of the hermetical silica shell. The gravitational force and the natural driving force of lowering the surface energy tend to interlink the carbon core and carbon/silica shell, resulting in a core-shell interlinked structure. After the SiO2 shell was etched, the mesoporous carbon shell was generated. When used as the sulfur host for Li-S batteries, such a hierarchical structure provides access to Li(+) ingress/egress for reactivity with the sulfur and, meanwhile, can overcome the limitations of low sulfur loading and a severe shuttle effect in solid carbon-supported sulfur cathodes. Transmission electron microscopy and scanning transmission electron microscopy images provide visible evidence that sulfur is well-encapsulated in the hollow void. Importantly, such anchored-core carbon nanostructures can simultaneously serve as a physical buffer and an electronically connecting matrix, which helps to realize the full potential of the active materials. Based on the many merits, carbon-sulfur cathodes show a high utilization of sulfur with a sulfur loading of 70 wt % and exhibit excellent cycling stability (i.e., 960 mA h g(-1) after 200 cycles at a current density of 0.5 C). PMID:26182333

  9. Engineering of Hollow Core-Shell Interlinked Carbon Spheres for Highly Stable Lithium-Sulfur Batteries.

    PubMed

    Sun, Qiang; He, Bin; Zhang, Xiang-Qian; Lu, An-Hui

    2015-08-25

    We report engineered hollow core-shell interlinked carbon spheres that consist of a mesoporous shell, a hollow void, and an anchored carbon core and are expected to be ideal sulfur hosts for overcoming the shortage of Li-S batteries. The hollow core-shell interlinked carbon spheres were obtained through solution synthesis of polymer spheres followed by a pyrolysis process that occurred in the hermetical silica shell. During the pyrolysis, the polymer sphere was transformed into the carbon core and the carbonaceous volatiles were self-deposited on the silica shell due to the blocking effect of the hermetical silica shell. The gravitational force and the natural driving force of lowering the surface energy tend to interlink the carbon core and carbon/silica shell, resulting in a core-shell interlinked structure. After the SiO2 shell was etched, the mesoporous carbon shell was generated. When used as the sulfur host for Li-S batteries, such a hierarchical structure provides access to Li(+) ingress/egress for reactivity with the sulfur and, meanwhile, can overcome the limitations of low sulfur loading and a severe shuttle effect in solid carbon-supported sulfur cathodes. Transmission electron microscopy and scanning transmission electron microscopy images provide visible evidence that sulfur is well-encapsulated in the hollow void. Importantly, such anchored-core carbon nanostructures can simultaneously serve as a physical buffer and an electronically connecting matrix, which helps to realize the full potential of the active materials. Based on the many merits, carbon-sulfur cathodes show a high utilization of sulfur with a sulfur loading of 70 wt % and exhibit excellent cycling stability (i.e., 960 mA h g(-1) after 200 cycles at a current density of 0.5 C).

  10. Thermo-Chemical Convection in Europa's Icy Shell with Salinity

    NASA Technical Reports Server (NTRS)

    Han, L.; Showman, A. P.

    2005-01-01

    Europa's icy surface displays numerous pits, uplifts, and chaos terrains that have been suggested to result from solid-state thermal convection in the ice shell, perhaps aided by partial melting. However, numerical simulations of thermal convection show that plumes have insufficient buoyancy to produce surface deformation. Here we present numerical simulations of thermochemical convection to test the hypothesis that convection with salinity can produce Europa's pits and domes. Our simulations show that domes (200-300 m) and pits (300-400 m) comparable to the observations can be produced in an ice shell of 15 km thick with 5-10% compositional density variation if the maximum viscosity is less than 10(exp 18) Pa sec. Additional information is included in the original extended abstract.

  11. The metrology of spherical shells using synchrotron x ray microtomography

    NASA Technical Reports Server (NTRS)

    Hmelo, Anthony B.; Allen, James L.; Damico, Kevin L.

    1990-01-01

    With recent advances in solid state imaging technology and the increasing availability of synchrotron x-ray radiation sources, synchrotron x-ray microtomography is emerging as a nondestructive technique for the evaluation of the structure and composition of small specimens with spatial resolution in the micron range. Synchrotron radiation offers the following advantages over conventional x-ray sources: high brightness, continuous emission which is tunable over a large energy range, faster data collection rates, and a highly collimated beam of large cross section permitting the illumination of large specimens. Synchrotron x-ray microtomography enables the structure of individual spheres to be evaluated in order to reveal the concentricity and sphericity of the internal void and the uniformity of the shell wall in the case of high quality spherical shells for Sandia National Laboratories' Inertial Confinement Fusion project.

  12. On the crystallization of spheres and shells

    NASA Astrophysics Data System (ADS)

    Hallett, J.

    1990-01-01

    Isolated drops of many solutions or pure materials readily supercool below their equilibrium crystallization point. In some cases a glass forms; otherwise the crystallization process is usually initiaed at a specific point in the drop leading to a complex structure. Under moderate supercooling, in the first stage of crystallization dendrites grow throughout the drop, leading to latent heat release, and temperature rise. The dendrite growth velocity, tip radius and crystal orientation depend critically on the supercooling. The second stage of crystallization depends on the geometry of the heat loss from the periphery and results in freezing from one side of the drop for asymmetric heat loss or as a thickening shell for symmetrical heat loss. Most solute is rejected at this stage, to nucleate in a geometry determined by the original dendrite distribution and the growth interface, and the internal pressure as it responds to volume changes and cracking of the shell. New crystal orientation appear for nucleation at large supercooling and also in large drops, following reorientation of dendrite arms separated during Ostwald Ripening. Crystal growth is usually uninfluenced by the interface in a gas or liquid environment but changes habit to thin needle like crystals, and increases growth velocity for a solid interface. Drops of size of the tip radius will no longer be spherical on crystallization. For a solvent which evaporates, crystals grow faceted (as hydrates); surface tension forces may move solvent over the surface to give well formed faceted crystals. It is suggested that faceted defect free crystals can be grown from drops under low g using controlled nucleation in a controlled vapor and temperature environment in the absence of convective motion.

  13. GaAs Core/SrTiO3 Shell Nanowires Grown by Molecular Beam Epitaxy.

    PubMed

    Guan, X; Becdelievre, J; Meunier, B; Benali, A; Saint-Girons, G; Bachelet, R; Regreny, P; Botella, C; Grenet, G; Blanchard, N P; Jaurand, X; Silly, M G; Sirotti, F; Chauvin, N; Gendry, M; Penuelas, J

    2016-04-13

    We have studied the growth of a SrTiO3 shell on self-catalyzed GaAs nanowires grown by vapor-liquid-solid assisted molecular beam epitaxy on Si(111) substrates. To control the growth of the SrTiO3 shell, the GaAs nanowires were protected using an arsenic capping/decapping procedure in order to prevent uncontrolled oxidation and/or contamination of the nanowire facets. Reflection high energy electron diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy were performed to determine the structural, chemical, and morphological properties of the heterostructured nanowires. Using adapted oxide growth conditions, it is shown that most of the perovskite structure SrTiO3 shell appears to be oriented with respect to the GaAs lattice. These results are promising for achieving one-dimensional epitaxial semiconductor core/functional oxide shell nanostructures. PMID:27008537

  14. GaAs Core/SrTiO3 Shell Nanowires Grown by Molecular Beam Epitaxy.

    PubMed

    Guan, X; Becdelievre, J; Meunier, B; Benali, A; Saint-Girons, G; Bachelet, R; Regreny, P; Botella, C; Grenet, G; Blanchard, N P; Jaurand, X; Silly, M G; Sirotti, F; Chauvin, N; Gendry, M; Penuelas, J

    2016-04-13

    We have studied the growth of a SrTiO3 shell on self-catalyzed GaAs nanowires grown by vapor-liquid-solid assisted molecular beam epitaxy on Si(111) substrates. To control the growth of the SrTiO3 shell, the GaAs nanowires were protected using an arsenic capping/decapping procedure in order to prevent uncontrolled oxidation and/or contamination of the nanowire facets. Reflection high energy electron diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy were performed to determine the structural, chemical, and morphological properties of the heterostructured nanowires. Using adapted oxide growth conditions, it is shown that most of the perovskite structure SrTiO3 shell appears to be oriented with respect to the GaAs lattice. These results are promising for achieving one-dimensional epitaxial semiconductor core/functional oxide shell nanostructures.

  15. Method and apparatus for an inflatable shell

    NASA Technical Reports Server (NTRS)

    Johnson, Christopher J. (Inventor)

    2012-01-01

    A method of assembling an inflatable shell of a structure comprises folding a plurality of shell sections about a set of fold lines and integrating the plurality of shell sections together with one another to form the shell. In another embodiment, an inflatable shell comprises a plurality of shell sections, each shell section having two pairs of fold lines for folding into stowage comprising a first gore section having a plurality of first gore panels layered and collectively folded about at a first set of fold lines. Each layer of the first gore panels and second gore panels are configured such that, once the first gore panel and second gore panel are attached to one another at the respective side edges of each panel, the lines of attachment forming a second set of fold lines for the shell section. A system and method for fabricating gore panels is also disclosed.

  16. Platinum Monolayer on IrFe Core-Shell Nanoparticle Electrocatalysts for the Oxygen Reduction Reaction

    SciTech Connect

    K Sasaki; K Kuttiyiel; D Su; R Adzic

    2011-12-31

    We synthesized high activity and stability platinum monolayer on IrFe core-shell nanoparticle electrocatalysts. Carbon-supported IrFe core-shell nanoparticles were synthesized by chemical reduction and subsequent thermal annealing. The formation of Ir shells on IrFe solid-solution alloy cores has been verified by scanning transmission electron microscopy coupled with energy-loss spectroscopy (EELS) and in situ X-ray absorption spectroscopy. The Pt monolayers were deposited on IrFe core-shell nanoparticles by galvanic replacement of underpotentially deposited Cu adatoms on the Ir shell surfaces. The specific and Pt mass activities for the ORR on the Pt monolayer on IrFe core-shell nanoparticle electrocatalyst are 0.46 mA/cm{sup 2} and 1.1 A/mg{sub Pt}, which are much higher than those on a commercial Pt/C electrocatalyst. High durability of Pt{sub ML}/IrFe/C has also been demonstrated by potential cycling tests. These high activity and durability observed can be ascribed to the structural and electronic interaction between the Pt monolayer and the IrFe core-shell nanoparticles.

  17. Platinum Monolayer on IrFe Core–Shell Nanoparticle Electrocatalysts for the Oxygen Reduction Reaction

    SciTech Connect

    Sasaki K.; Kuttiyiel, K.A.; Su, D.; Adzic, R.R.

    2012-04-19

    We synthesized high activity and stability platinum monolayer on IrFe core-shell nanoparticle electrocatalysts. Carbon-supported IrFe core-shell nanoparticles were synthesized by chemical reduction and subsequent thermal annealing. The formation of Ir shells on IrFe solid-solution alloy cores has been verified by scanning transmission electron microscopy coupled with energy-loss spectroscopy (EELS) and in situ X-ray absorption spectroscopy. The Pt monolayers were deposited on IrFe core-shell nanoparticles by galvanic replacement of underpotentially deposited Cu adatoms on the Ir shell surfaces. The specific and Pt mass activities for the ORR on the Pt monolayer on IrFe core-shell nanoparticle electrocatalyst are 0.46 mA/cm{sup 2} and 1.1 A/mg{sub Pt}, which are much higher than those on a commercial Pt/C electrocatalyst. High durability of Pt{sub ML}/IrFe/C has also been demonstrated by potential cycling tests. These high activity and durability observed can be ascribed to the structural and electronic interaction between the Pt monolayer and the IrFe core-shell nanoparticles.

  18. Shell structures for biogas plants

    SciTech Connect

    Sasse, L.

    1982-01-01

    The shell structures designed for biogas plants of the fixed-dome type by the Bremen Overseas Research and Development Association are described. Biogas digesters of the design described have been successfully tested in Rwanda and India without structural or contractural problems.

  19. Finite element shell instability analysis

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Formulation procedures and the associated computer program for finite element thin shell instability analysis are discussed. Data cover: (1) formulation of basic element relationships, (2) construction of solution algorithms on both the conceptual and algorithmic levels, and (3) conduction of numerical analyses to verify the accuracy and efficiency of the theory and related programs therein are described.

  20. Shell Games: Uncovering Periodic Properties.

    ERIC Educational Resources Information Center

    Lamb, William G.

    1983-01-01

    Describes activities (demonstrations/experiments) used to introduce history of periodic properties--without electrons, orbitals, filling shells, or any conception of atoms beyond Dalton's model. Activities supplement first chapter in a currently available chemistry text. Indicates potential danger of experiments if proper safety precautions are…

  1. Notes on static cylindrical shells

    NASA Astrophysics Data System (ADS)

    Bicák, J.; Zofka, M.

    2002-07-01

    Static cylindrical shells made of various types of matter are studied as sources of the vacuum Levi-Civita metrics. Their internal physical properties are related to the two essential parameters of the metrics outside. The total mass per unit length of the cylinders is always less than ¼. The results are illustrated by a number of figures.

  2. Bases for solid waste volume estimates for tank waste remediation system

    SciTech Connect

    Reddick, G.W., Westinghouse Hanford

    1996-08-01

    This document presents the background and basis for the Tank Waste Remediation System forecast for solid waste submitted in June 1996. The forecast was generated for single-shell tank and double-shell tank activities including operations through retrieval and disposal of chemical tank waste.

  3. Industrial mixing techniques for Hanford double-shell tanks

    SciTech Connect

    Daymo, E.A.

    1997-09-01

    Jet mixer pumps are currently the baseline technology for sludge mobilization and mixing in one-million gallon double-shell tanks at the Hanford and Savannah River Sites. Improvements to the baseline jet mixer pump technology are sought because jet mixer pumps have moving parts that may fail or require maintenance. Moreover, jet mixers are relatively expensive, they heat the waste, and, in some cases, may not mobilize enough of the sludge. This report documents a thorough literature search for commercially available applicable mixing technologies that could be used for double-shell tank sludge mobilization and mixing. Textbooks, research articles, conference proceedings, mixing experts, and the Thomas Register were consulted to identify applicable technologies. While there are many commercial methods that could be used to mobilize sludge or mix the contents of a one-million gallon tank, few will work given the geometrical constraints (e.g., the mixer must fit through a 1.07-m-diameter riser) or the tank waste properties (e.g., the sludge has such a high yield stress that it generally does not flow under its own weight). Pulsed fluid jets and submersible Flygt mixers have already been identified at Hanford and Savannah River Sites for double-shell tank mixing applications. While these mixing technologies may not be applicable for double-shell tanks that have a thick sludge layer at the bottom (since too many of these mixers would need to be installed to mobilize most of the sludge), they may have applications in tanks that do not have a settled solids layer. Retrieval projects at Hanford and other U.S. Department of Energy sites are currently evaluating the effectiveness of these mixing techniques for tank waste applications. The literature search did not reveal any previously unknown technologies that should be considered for sludge mobilization and mixing in one-million gallon double-shell tanks.

  4. NMR and ESR characterization of activated carbons produced from pecan shells

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A large number of solid-state NMR and ESR experiments were explored as potential tools to study chemical structure, mobility, and pore volume of activated carbon. We used a model system where pecan shells were activated with phosphoric acid, and carbonized at 450ºC for 4 h with varying amounts of ai...

  5. Recent advances in shell theory. [application of asymptotic approach to thin walled shells

    NASA Technical Reports Server (NTRS)

    Simmonds, J. G.

    1976-01-01

    The results reviewed are divided into two categories: those that relate two-dimensional shell theory to three-dimensional elasticity theory and those concerned with shell theory per se. In the second category results for general elastic systems that carry over, by specialization or analogy, to shells and results that are unique to shell theory itself are considered.

  6. 7 CFR 983.29 - Shelled pistachios.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Shelled pistachios. 983.29 Section 983.29 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE PISTACHIOS GROWN IN CALIFORNIA, ARIZONA, AND NEW MEXICO Definitions § 983.29 Shelled pistachios. Shelled pistachios means...

  7. 7 CFR 984.10 - Shelled walnuts.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 8 2012-01-01 2012-01-01 false Shelled walnuts. 984.10 Section 984.10 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE WALNUTS GROWN IN CALIFORNIA Order Regulating Handling Definitions § 984.10 Shelled walnuts. Shelled walnuts means walnut kernels after...

  8. 7 CFR 984.10 - Shelled walnuts.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 8 2011-01-01 2011-01-01 false Shelled walnuts. 984.10 Section 984.10 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE WALNUTS GROWN IN CALIFORNIA Order Regulating Handling Definitions § 984.10 Shelled walnuts. Shelled walnuts means walnut kernels after...

  9. 7 CFR 984.10 - Shelled walnuts.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 8 2014-01-01 2014-01-01 false Shelled walnuts. 984.10 Section 984.10 Agriculture... AND ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE WALNUTS GROWN IN CALIFORNIA Order Regulating Handling Definitions § 984.10 Shelled walnuts. Shelled walnuts means walnut kernels after...

  10. 7 CFR 984.10 - Shelled walnuts.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Shelled walnuts. 984.10 Section 984.10 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE WALNUTS GROWN IN CALIFORNIA Order Regulating Handling Definitions § 984.10 Shelled walnuts. Shelled walnuts means walnut kernels after...

  11. 7 CFR 984.10 - Shelled walnuts.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 8 2013-01-01 2013-01-01 false Shelled walnuts. 984.10 Section 984.10 Agriculture... AND ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE WALNUTS GROWN IN CALIFORNIA Order Regulating Handling Definitions § 984.10 Shelled walnuts. Shelled walnuts means walnut kernels after...

  12. 21 CFR 886.3800 - Scleral shell.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Scleral shell. 886.3800 Section 886.3800 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Prosthetic Devices § 886.3800 Scleral shell. (a) Identification. A scleral shell is...

  13. 7 CFR 981.6 - Shelled almonds.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Shelled almonds. 981.6 Section 981.6 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE ALMONDS GROWN IN CALIFORNIA Order Regulating Handling Definitions § 981.6 Shelled almonds. Shelled almonds mean raw or roasted almonds...

  14. 7 CFR 981.6 - Shelled almonds.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 8 2013-01-01 2013-01-01 false Shelled almonds. 981.6 Section 981.6 Agriculture... AND ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE ALMONDS GROWN IN CALIFORNIA Order Regulating Handling Definitions § 981.6 Shelled almonds. Shelled almonds mean raw or roasted almonds...

  15. 7 CFR 981.6 - Shelled almonds.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 8 2012-01-01 2012-01-01 false Shelled almonds. 981.6 Section 981.6 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE ALMONDS GROWN IN CALIFORNIA Order Regulating Handling Definitions § 981.6 Shelled almonds. Shelled almonds mean raw or roasted almonds...

  16. 7 CFR 981.6 - Shelled almonds.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 8 2014-01-01 2014-01-01 false Shelled almonds. 981.6 Section 981.6 Agriculture... AND ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE ALMONDS GROWN IN CALIFORNIA Order Regulating Handling Definitions § 981.6 Shelled almonds. Shelled almonds mean raw or roasted almonds...

  17. 7 CFR 981.6 - Shelled almonds.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 8 2011-01-01 2011-01-01 false Shelled almonds. 981.6 Section 981.6 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE ALMONDS GROWN IN CALIFORNIA Order Regulating Handling Definitions § 981.6 Shelled almonds. Shelled almonds mean raw or roasted almonds...

  18. Developments in Cylindrical Shell Stability Analysis

    NASA Technical Reports Server (NTRS)

    Knight, Norman F., Jr.; Starnes, James H., Jr.

    1998-01-01

    Today high-performance computing systems and new analytical and numerical techniques enable engineers to explore the use of advanced materials for shell design. This paper reviews some of the historical developments of shell buckling analysis and design. The paper concludes by identifying key research directions for reliable and robust methods development in shell stability analysis and design.

  19. 7 CFR 983.29 - Shelled pistachios.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 8 2012-01-01 2012-01-01 false Shelled pistachios. 983.29 Section 983.29 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE PISTACHIOS GROWN IN CALIFORNIA, ARIZONA, AND NEW MEXICO Definitions § 983.29 Shelled pistachios. Shelled pistachios means...

  20. 7 CFR 983.29 - Shelled pistachios.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 8 2013-01-01 2013-01-01 false Shelled pistachios. 983.29 Section 983.29 Agriculture... AND ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE PISTACHIOS GROWN IN CALIFORNIA, ARIZONA, AND NEW MEXICO Definitions § 983.29 Shelled pistachios. Shelled pistachios means...

  1. 7 CFR 983.29 - Shelled pistachios.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 8 2011-01-01 2011-01-01 false Shelled pistachios. 983.29 Section 983.29 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE PISTACHIOS GROWN IN CALIFORNIA, ARIZONA, AND NEW MEXICO Definitions § 983.29 Shelled pistachios. Shelled pistachios means...

  2. 7 CFR 983.29 - Shelled pistachios.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 8 2014-01-01 2014-01-01 false Shelled pistachios. 983.29 Section 983.29 Agriculture... AND ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE PISTACHIOS GROWN IN CALIFORNIA, ARIZONA, AND NEW MEXICO Definitions § 983.29 Shelled pistachios. Shelled pistachios means...

  3. Shell Model Depiction of Isospin Mixing in sd Shell

    SciTech Connect

    Lam, Yi Hua; Smirnova, Nadya A.; Caurier, Etienne

    2011-11-30

    We constructed a new empirical isospin-symmetry breaking (ISB) Hamiltonian in the sd(1s{sub 1/2}, 0d{sub 5/2} and 0d{sub 3/2}) shell-model space. In this contribution, we present its application to two important case studies: (i){beta}-delayed proton emission from {sup 22}Al and (ii) isospin-mixing correction to superallowed 0{sup +}{yields}0{sup +}{beta}-decay ft-values.

  4. On chaotic behavior of gravitating stellar shells.

    PubMed

    Barkov, M V; Bisnovatyi-Kogan, G S; Neishtadt, A I; Belinski, V A

    2005-03-01

    Motion of two gravitating spherical stellar shells around a massive central body is considered. Each shell consists of point particles with the same specific angular momenta and energies. In the case when one can neglect the influence of gravitation of one ("light") shell onto another ("heavy") shell ("restricted problem") the structure of the phase space is described. The scaling laws for the measure of the domain of chaotic motion and for the minimal energy of the light shell sufficient for its escape to infinity are obtained. PMID:15836258

  5. Solid electrolytes

    DOEpatents

    Abraham, Kuzhikalail M.; Alamgir, Mohamed

    1993-06-15

    This invention pertains to Li ion (Li.sup.+) conductive solid polymer electrolytes composed of solvates of Li salts immobilized (encapsulated) in a solid organic polymer matrix. In particular, this invention relates to solid polymer electrolytes derived by immobilizing complexes (solvates) formed between a Li salt such as LiAsF.sub.6, LiCF.sub.3 SO.sub.3 or LiClO.sub.4 and a mixture of aprotic organic solvents having high dielectric constants such as ethylene carbonate (EC) (dielectric constant=89.6) and propylene carbonate (PC) (dielectric constant=64.4) in a polymer matrix such as polyacrylonitrile, poly(tetraethylene glycol diacrylate), or poly(vinyl pyrrolidinone).

  6. Molecular phylogeny of the acorn barnacle family Tetraclitidae (Cirripedia: Balanomorpha: Tetraclitoidea): validity of shell morphology and arthropodal characteristics in the systematics of Tetraclitid barnacles.

    PubMed

    Tsang, Ling Ming; Chu, Ka Hou; Achituv, Yair; Chan, Benny Kwok Kan

    2015-01-01

    Shell structure is a crucial aspect of barnacle systematics. Within Tetraclitidae, the diametric and monometric growth patterns and number of rows of parietal tubes in the shells are key characteristics used to infer evolutionary trends. We used molecular analysis based on seven genes (mitochondrial COI, 16S and 12S rRNA, and nuclear EF1, RPII, H3, and 18S rRNA) to test two traditional phylogenetic hypothesis: (1) Tetraclitid barnacles are divided into two major lineages, which are distinguished according to monometric and diametric shell growth patterns, and (2) the evolutionary trend in shell parietal development began with a solid shell, which developed into a single tubiferous shell, which then developed into multitubiferous shells. The results indicated that Tetraclitinae and Newmanellinae are not monophyletic, but that Austrobalaninae and Tetraclitellinae are. The phylogram based on the genetic data suggested that Bathylasmatidae is nested within the Tetraclitidae, forming a sister relationship with the Austrobalaninae and Tetraclitinae/Newmanellinae clade. Within the Tetraclitinae/Newmanellinae clade, the genera Tetraclita (multitubiferous shell), Tesseropora (single tubiferous shell), and Yamaguchiella (multitubiferous shell) are polyphyletic. The results suggested that shell morphology and growth patterns do not reflect the evolutionary history of Tetraclitidae, whereas the arthropodal characteristics are informative. PMID:25263422

  7. Molecular phylogeny of the acorn barnacle family Tetraclitidae (Cirripedia: Balanomorpha: Tetraclitoidea): validity of shell morphology and arthropodal characteristics in the systematics of Tetraclitid barnacles.

    PubMed

    Tsang, Ling Ming; Chu, Ka Hou; Achituv, Yair; Chan, Benny Kwok Kan

    2015-01-01

    Shell structure is a crucial aspect of barnacle systematics. Within Tetraclitidae, the diametric and monometric growth patterns and number of rows of parietal tubes in the shells are key characteristics used to infer evolutionary trends. We used molecular analysis based on seven genes (mitochondrial COI, 16S and 12S rRNA, and nuclear EF1, RPII, H3, and 18S rRNA) to test two traditional phylogenetic hypothesis: (1) Tetraclitid barnacles are divided into two major lineages, which are distinguished according to monometric and diametric shell growth patterns, and (2) the evolutionary trend in shell parietal development began with a solid shell, which developed into a single tubiferous shell, which then developed into multitubiferous shells. The results indicated that Tetraclitinae and Newmanellinae are not monophyletic, but that Austrobalaninae and Tetraclitellinae are. The phylogram based on the genetic data suggested that Bathylasmatidae is nested within the Tetraclitidae, forming a sister relationship with the Austrobalaninae and Tetraclitinae/Newmanellinae clade. Within the Tetraclitinae/Newmanellinae clade, the genera Tetraclita (multitubiferous shell), Tesseropora (single tubiferous shell), and Yamaguchiella (multitubiferous shell) are polyphyletic. The results suggested that shell morphology and growth patterns do not reflect the evolutionary history of Tetraclitidae, whereas the arthropodal characteristics are informative.

  8. Pressure Shell Approach to Integrated Environmental Protection

    NASA Technical Reports Server (NTRS)

    Kennedy, Kriss J.

    2011-01-01

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

  9. Turbine blade with spar and shell

    DOEpatents

    Davies, Daniel O.; Peterson, Ross H.

    2012-04-24

    A turbine blade with a spar and shell construction in which the spar and the shell are both secured within two platform halves. The spar and the shell each include outward extending ledges on the bottom ends that fit within grooves formed on the inner sides of the platform halves to secure the spar and the shell against radial movement when the two platform halves are joined. The shell is also secured to the spar by hooks extending from the shell that slide into grooves formed on the outer surface of the spar. The hooks form a serpentine flow cooling passage between the shell and the spar. The spar includes cooling holes on the lower end in the leading edge region to discharge cooling air supplied through the platform root and into the leading edge cooling channel.

  10. Indentation of Ellipsoidal and Cylindrical Elastic Shells

    NASA Astrophysics Data System (ADS)

    Vella, Dominic; Ajdari, Amin; Vaziri, Ashkan; Boudaoud, Arezki

    2012-10-01

    Thin shells are found in nature at scales ranging from viruses to hens’ eggs; the stiffness of such shells is essential for their function. We present the results of numerical simulations and theoretical analyses for the indentation of ellipsoidal and cylindrical elastic shells, considering both pressurized and unpressurized shells. We provide a theoretical foundation for the experimental findings of Lazarus et al. [following paper, Phys. Rev. Lett. 109, 144301 (2012)PRLTAO0031-9007] and for previous work inferring the turgor pressure of bacteria from measurements of their indentation stiffness; we also identify a new regime at large indentation. We show that the indentation stiffness of convex shells is dominated by either the mean or Gaussian curvature of the shell depending on the pressurization and indentation depth. Our results reveal how geometry rules the rigidity of shells.

  11. Shell Evolutions and Nuclear Forces

    NASA Astrophysics Data System (ADS)

    Sorlin, O.

    2014-03-01

    During the last 30 years, and more specifically during the last 10 years, many experiments have been carried out worldwide using different techniques to study the shell evolution of nuclei far from stability. What seemed not conceivable some decades ago became rather common: all known magic numbers that are present in the valley of stability disappear far from stability and are replaced by new ones at the drip line. By gathering selected experimental results, beautifully consistent pictures emerge, that very likely take root in the properties of the nuclear forces.The present manuscript describes some of these discoveries and proposes an intuitive understanding of these shell evolutions derived from observations. Extrapolations to yet unstudied regions, as where the explosive r-process nucleosynthesis occurs, are proposed. Some remaining challenges and puzzling questions are also addressed.

  12. Glass shell manufacturing in space

    NASA Technical Reports Server (NTRS)

    Nolen, R. L.; Downs, R. L.; Ebner, M. A.

    1982-01-01

    Highly-uniform, hollow glass spheres, which are used for inertial-confinement fusion targets, are formed from metal-organic gel powder feedstock in a drop-tower furnace. The modelling of this gel-to-sphere transformation has consisted of three phases: gel thermochemistry, furnance-to-gel heat transfer, and gravity-driven degradation of the concentricity of the molten shell. The heat transfer from the furnace to the free-falling gel particle was modelled with forced convection. The gel mass, dimensions, and specific heat as well as furnace temperature profile and furnace gas conductivity, were controlled variables. This model has been experimentally verified. In the third phase, a mathematical model was developed to describe the gravity-driven degradation of concentricity in molten glass shells.

  13. Density Measurements of Be Shells

    SciTech Connect

    Cook, R C

    2005-02-15

    The purpose of this memo is to lay out the uncertainties associated with the measurement of density of Be ablators by the weigh and volume method. I am counting on the readers to point out any faulty assumptions about the techniques or uncertainties associated with them. Based on the analysis presented below we should expect that 30 {micro}m thick shells will have an uncertainty in the measured density of about 2% of the value, coming more or less equally from the mass and volume measurement. The uncertainty is roughly inversely proportional to the coating thickness, thus a 60 {micro}m walled shell would result in a 1% uncertainty in the density.

  14. The shell coal gasification process

    SciTech Connect

    Koenders, L.O.M.; Zuideveld, P.O.

    1995-12-01

    Future Integrated Coal Gasification Combined Cycle (ICGCC) power plants will have superior environmental performance and efficiency. The Shell Coal Gasification Process (SCGP) is a clean coal technology, which can convert a wide range of coals into clean syngas for high efficiency electricity generation in an ICGCC plant. SCGP flexibility has been demonstrated for high-rank bituminous coals to low rank lignites and petroleum coke, and the process is well suited for combined cycle power generation, resulting in efficiencies of 42 to 46% (LHV), depending on choice of coal and gas turbine efficiency. In the Netherlands, a 250 MWe coal gasification combined cycle plant based on Shell technology has been built by Demkolec, a development partnership of the Dutch Electricity Generating Board (N.V. Sep). The construction of the unit was completed end 1993 and is now followed by start-up and a 3 year demonstration period, after that the plant will be part of the Dutch electricity generating system.

  15. Premature detonation problem. [Artillery shells

    SciTech Connect

    Pimbley, G.H.; Marshall, E.F.

    1980-05-01

    Determining how cavities or voids in the explosive loads of artillery shells cause in-bore premature detonations is important to military authorities. Though answers continue to be elusive, in detailing recent studies of the problem at LASL, some traditional approaches were examined and a new direction of investigation is suggested. The aquarium experiment and the pipe test were devised at LASL to model the events taking place in a base gap, or in an internal cavity, in the load of an accelerating artillery shell. Numerical simulation was used to assess the data from these experiments. Both the experimental and the numerical simulation phases of the project are described. The commonly accepted gas compression, thermal ignition mechanism is not consistent with the results of this study. The dominant mechanism or mechanisms have not been identified.

  16. Shell Models of Superfluid Turbulence

    NASA Astrophysics Data System (ADS)

    Wacks, Daniel H.; Barenghi, Carlo F.

    2011-12-01

    Superfluid helium consists of two inter-penetrating fluids, a viscous normal fluid and an inviscid superfluid, coupled by a mutual friction. We develop a two-fluid shell model to study superfluid turbulence and investigate the energy spectra and the balance of fluxes between the two fluids in a steady state. At sufficiently low temperatures a 'bottle-neck' develops at high wavenumbers suggesting the need for a further dissipative effect, such as the Kelvin wave cascade.

  17. Inner-shell excitation spectroscopy of peroxides

    NASA Astrophysics Data System (ADS)

    Harding, K. L.; Kalirai, S.; Hayes, R.; Ju, V.; Cooper, G.; Hitchcock, A. P.; Thompson, M. R.

    2015-11-01

    O 1s inner-shell excitation spectra of a number of vapor phase molecules containing peroxide bonds - hydrogen peroxide (H2O2), di-t-butylperoxide (tBuOtBu), benzoyl peroxide, ((C6H5(CO)O)2), luperox-F [1,3(4)-bis(tertbutylperoxyisopropyl) benzene], and analogous, non-peroxide compounds - water, t-butanol and benzoic acid have been measured. C 1s spectra are also reported. O 1s spectra of solid benzoic acid, di-t-butylperoxide and luperox-F recorded using a scanning transmission X-ray microscope, are also reported, and compared to the corresponding gaseous spectra. Spectral interpretation was aided by comparing the spectra of the peroxide and non-peroxide counterparts and with ab initio calculations. A characteristic O 1s → σ∗O-O transition at 533.0(3) eV is identified in each peroxide species, which is absent in the corresponding non-peroxide counterpart species. The energy and intensity of the 533 eV peroxide feature is stable and thus useful for analysis of peroxides in mixtures, such as tracking residual peroxide initiators, or peroxides produced in fuel cells.

  18. Atomic inner-shell transitions

    NASA Technical Reports Server (NTRS)

    Crasemann, B.; Chen, M. H.; Mark, H.

    1984-01-01

    Atomic inner-shell processes have quite different characteristics, in several important aspects, from processes in the optical regime. Energies are large, e.g., the 1s binding energy reaches 100 keV at Z = 87; relativistic and quantum-electrodynamic effects therefore are strong. Radiationless transitions vastly dominate over photon emission in most cases. Isolated inner-shell vacancies have pronounced single-particle character, with correlations generally contributing only approximately 1 eV to the 1s and 2p binding energies; the structure of such systems is thus well tractable by independent-particle self-consistent-field atomic models. For systems containing multiple deep inner-shell vacancies, or for highly stripped ions, the importance of relativistic intermediate coupling and configuration interaction becomes pronounced. Cancellation of the Coulomb interaction can lead to strong manifestations of the Breit interaction in such phenomena as multiplet splitting and hypersatellite X-ray shifts. Unique opportunities arise for the test of theory.

  19. Liquefaction of bamboo shoot shell for the production of polyols.

    PubMed

    Ye, Liyi; Zhang, Jingmiao; Zhao, Jie; Tu, Song

    2014-02-01

    Bamboo (Dendrocalamus latiflorus Munro) shoot shell (BSS) was liquefied in polyethylene glycol 400 (PEG400) and ethylene glycol (EG) catalyzed by sulfuric acid under atmospheric pressure. The effects of liquefaction conditions such as liquid-solid ratio, temperature, time, catalyst, solvents ratio, and material size on the liquefaction yield of BSS have been investigated. Methods including Elemental analysis, Thermogravimetric analysis, Fourier transform infrared spectroscopy, nuclear magnetic resonance and gas chromatography-mass spectrometry were selected to analyze the characteristics of products in three fractions: an aqueous fraction (AQ), an acetone-soluble fraction (AS) and a residue (RS), respectively. Results showed that the highest liquefaction percentage was 99.79% under the optimal conditions (liquid-solid ratio 6:1; temperature 150°C; reaction time 80min; raw size more than 40 mesh; catalyst mass percentage of solvent 4%; solvent volume ratio 3:1). Polyols could be obtained effectively by the liquefaction of BSS, an agricultural by-product.

  20. Isogeometric Kirchhoff-Love shell formulations for biological membranes

    PubMed Central

    Tepole, Adrián Buganza; Kabaria, Hardik; Bletzinger, Kai-Uwe; Kuhl, Ellen

    2015-01-01

    Computational modeling of thin biological membranes can aid the design of better medical devices. Remarkable biological membranes include skin, alveoli, blood vessels, and heart valves. Isogeometric analysis is ideally suited for biological membranes since it inherently satisfies the C1-requirement for Kirchhoff-Love kinematics. Yet, current isogeometric shell formulations are mainly focused on linear isotropic materials, while biological tissues are characterized by a nonlinear anisotropic stress-strain response. Here we present a thin shell formulation for thin biological membranes. We derive the equilibrium equations using curvilinear convective coordinates on NURBS tensor product surface patches. We linearize the weak form of the generic linear momentum balance without a particular choice of a constitutive law. We then incorporate the constitutive equations that have been designed specifically for collagenous tissues. We explore three common anisotropic material models: Mooney-Rivlin, May Newmann-Yin, and Gasser-Ogden-Holzapfel. Our work will allow scientists in biomechanics and mechanobiology to adopt the constitutive equations that have been developed for solid three-dimensional soft tissues within the framework of isogeometric thin shell analysis. PMID:26251556

  1. Analysis of Composite Skin-Stiffener Debond Specimens Using a Shell/3D Modeling Technique and Submodeling

    NASA Technical Reports Server (NTRS)

    OBrien, T. Kevin (Technical Monitor); Krueger, Ronald; Minguet, Pierre J.

    2004-01-01

    The application of a shell/3D modeling technique for the simulation of skin/stringer debond in a specimen subjected to tension and three-point bending was studied. The global structure was modeled with shell elements. A local three-dimensional model, extending to about three specimen thicknesses on either side of the delamination front was used to model the details of the damaged section. Computed total strain energy release rates and mixed-mode ratios obtained from shell/3D simulations were in good agreement with results obtained from full solid models. The good correlation of the results demonstrated the effectiveness of the shell/3D modeling technique for the investigation of skin/stiffener separation due to delamination in the adherents. In addition, the application of the submodeling technique for the simulation of skin/stringer debond was also studied. Global models made of shell elements and solid elements were studied. Solid elements were used for local submodels, which extended between three and six specimen thicknesses on either side of the delamination front to model the details of the damaged section. Computed total strain energy release rates and mixed-mode ratios obtained from the simulations using the submodeling technique were not in agreement with results obtained from full solid models.

  2. Rigid shells enhance survival of gekkotan eggs.

    PubMed

    Andrews, Robin M

    2015-11-01

    The majority of lizards and snakes produce permeable parchment-shelled eggs that require high moisture conditions for successful embryonic development. One clade of gekkotan lizards is an exception; females produce relatively impermeable rigid-shelled eggs that normally incubate successfully under low moisture conditions. I tested the hypothesis that the rigid-shell increases egg survival during incubation, but only under low moisture conditions. To test this hypothesis, I incubated rigid-shelled eggs of Chondrodactylus turneri under low and under high moisture conditions. Eggs were incubated with parchment-shelled eggs of Eublepharis macularius to insure that incubation conditions were suitable for parchment-shelled eggs. Chondrodactylus turneri eggs had very high survival (>90%) when they were incubated under low moisture conditions. In contrast, eggs incubated under high moisture conditions had low survival overall, and lower survival than those of the parchment-shelled eggs of E. macularius. Mortality of C. turneri and E. macularius eggs incubated under high moisture conditions was the result of fungal infection, a common source of egg mortality for squamates under laboratory and field conditions. These observations document high survival of rigid-shelled eggs under low moisture conditions because eggs escape from fungal infection. Highly mineralized rigid shells also make egg survival independent of moisture availability and may also provide protection from small invertebrates in nature. Enhanced egg survival could thus compensate for the low reproductive output of gekkotans that produce rigid-shelled eggs.

  3. Shape-tunable core-shell microparticles.

    PubMed

    Klein, Matthias K; Saenger, Nicolai R; Schuetter, Stefan; Pfleiderer, Patrick; Zumbusch, Andreas

    2014-10-28

    Colloidal polymer particles are an important class of materials finding use in both everyday and basic research applications. Tailoring their composition, shape, and functionality is of key importance. In this article, we describe a new class of shape-tunable core-shell microparticles. They are composed of a cross-linked polystyrene (PS) core and a poly(methyl methacrylate) (PMMA) shell of varying thickness. In the first step, we prepared highly cross-linked PS cores, which are subsequently transferred into a nonpolar dispersant. They serve as the seed dispersion for a nonaqueous dispersion polymerization to generate the PMMA shell. The shape of the particles can subsequently be manipulated. After the shell growth stage, the spherical PS/PMMA core-shell colloids exhibit an uneven and wrinkled surface. An additional tempering procedure allows for smoothing the surface of the core-shell colloids. This results in polymer core-shell particles with a perfectly spherical shape. In addition to this thermal smoothing of the PMMA shell, we generated a selection of shape-anisotropic core-shell particles using a thermomechanical stretching procedure. Because of the unique constitution, we can selectively interrogate molecular vibrations in the PS core or the PMMA shell of the colloids using nonlinear optical microscopy techniques. This is of great interest because no photobleaching occurs, such that the particles can be tracked in real space over long times.

  4. Coherently Strained Si-SixGe1-x Core-Shell Nanowire Heterostructures.

    PubMed

    Dillen, David C; Wen, Feng; Kim, Kyounghwan; Tutuc, Emanuel

    2016-01-13

    Coherently strained Si-SixGe1-x core-shell nanowire heterostructures are expected to possess a positive shell-to-core conduction band offset, allowing for quantum confinement of electrons in the Si core. We report the growth of epitaxial, coherently strained Si-SixGe1-x core-shell heterostructures through the vapor-liquid-solid mechanism for the Si core, followed in situ by the epitaxial SixGe1-x shell growth using ultrahigh vacuum chemical vapor deposition. The Raman spectra of individual nanowires reveal peaks associated with the Si-Si optical phonon mode in the Si core and the Si-Si, Si-Ge, and Ge-Ge vibrational modes of the SixGe1-x shell. The core Si-Si mode displays a clear red-shift compared to unstrained, bare Si nanowires thanks to the lattice mismatch-induced tensile strain, in agreement with calculated values using a finite-element continuum elasticity model combined with lattice dynamic theory. N-type field-effect transistors using Si-SixGe1-x core-shell nanowires as channel are demonstrated.

  5. Advanced solid elements for sheet metal forming simulation

    NASA Astrophysics Data System (ADS)

    Mataix, Vicente; Rossi, Riccardo; Oñate, Eugenio; Flores, Fernando G.

    2016-08-01

    The solid-shells are an attractive kind of element for the simulation of forming processes, due to the fact that any kind of generic 3D constitutive law can be employed without any additional hypothesis. The present work consists in the improvement of a triangular prism solid-shell originally developed by Flores[2, 3]. The solid-shell can be used in the analysis of thin/thick shell, undergoing large deformations. The element is formulated in total Lagrangian formulation, and employs the neighbour (adjacent) elements to perform a local patch to enrich the displacement field. In the original formulation a modified right Cauchy-Green deformation tensor (C) is obtained; in the present work a modified deformation gradient (F) is obtained, which allows to generalise the methodology and allows to employ the Pull-Back and Push-Forwards operations. The element is based in three modifications: (a) a classical assumed strain approach for transverse shear strains (b) an assumed strain approach for the in-plane components using information from neighbour elements and (c) an averaging of the volumetric strain over the element. The objective is to use this type of elements for the simulation of shells avoiding transverse shear locking, improving the membrane behaviour of the in-plane triangle and to handle quasi-incompressible materials or materials with isochoric plastic flow.

  6. Single-shell tank interim stabilization project plan

    SciTech Connect

    Ross, W.E.

    1998-03-27

    Solid and liquid radioactive waste continues to be stored in 149 single-shell tanks at the Hanford Site. To date, 119 tanks have had most of the pumpable liquid removed by interim stabilization. Thirty tanks remain to be stabilized. One of these tanks (C-106) will be stabilized by retrieval of the tank contents. The remaining 29 tanks will be interim stabilized by saltwell pumping. In the summer of 1997, the US Department of Energy (DOE) placed a moratorium on the startup of additional saltwell pumping systems because of funding constraints and proposed modifications to the Hanford Federal Facility Agreement and Consent Order (Tri-Party Agreement) milestones to the Washington State Department of Ecology (Ecology). In a letter dated February 10, 1998, Final Determination Pursuant to Hanford Federal Facility Agreement and Consent Order (Tri-Party Agreement) in the Matter of the Disapproval of the DOE`s Change Control Form M-41-97-01 (Fitzsimmons 1998), Ecology disapproved the DOE Change Control Form M-41-97-01. In response, Fluor Daniel Hanford, Inc. (FDH) directed Lockheed Martin Hanford Corporation (LNMC) to initiate development of a project plan in a letter dated February 25, 1998, Direction for Development of an Aggressive Single-Shell Tank (SST) Interim Stabilization Completion Project Plan in Support of Hanford Federal Facility Agreement and Consent Order (Tri-Party Agreement). In a letter dated March 2, 1998, Request for an Aggressive Single-Shell Tank (SST) Interim Stabilization Completion Project Plan, the DOE reaffirmed the need for an aggressive SST interim stabilization completion project plan to support a finalized Tri-Party Agreement Milestone M-41 recovery plan. This project plan establishes the management framework for conduct of the TWRS Single-Shell Tank Interim Stabilization completion program. Specifically, this plan defines the mission needs and requirements; technical objectives and approach; organizational structure, roles, responsibilities

  7. Rarefied solids

    NASA Technical Reports Server (NTRS)

    Noever, D. A.; Nikora, V. I.

    1994-01-01

    One important limit to creating low density materials is the objects' own weight. As a solid or colloidal matrix becomes more rarefied, gravity acts destructively to compress its suporting skeleton. We describe experimental results and propose a model which matches the low gravity behavior of rarefied or fractal solids. On parabolic airplane flights, we sought to demonstrate a key component of producing higher surface area fractals. Flight paths were selected to give a range of gravity levels: 0.01 g/g(sub 0) (low), 0.16 g(sub 0) (Lunar), 0.33 g/g(sub 0) (Martian), 1 g/g(sub 0) (Earth) and 1.8 g/g(sub 0) (high) (where g(sub 0) = 980 cm/sq s). Results using the model material of hydrophobic silica indicated that stable agglomeration of such tenuous objects can increase markedly in reduced gravity. Optical characterization revealed that fractal dimension changed directly with varying gravity. As measured by fractal dimension, effective surface area and roughness increased by 40% in low gravity. This finding supports the conclusion that relieving internal weight stresses on delicate aggregates can enhance their overall size (by two orders of magnitude) and internal surface area. We conclude that gravitational restructuring limits the overall size and void content of low-density solids. These sparse colloidal regimes may present new and technologically attractive physics, ranging from improved insulators, liquid-like tension in a 'solid' matrix, and characteristically low conductivities for sound and (8 to 14 micrometers wavelength) infrared radiation.

  8. Cracked shells under skew-symmetric loading

    NASA Technical Reports Server (NTRS)

    Lelale, F.

    1982-01-01

    A shell containing a through crack in one of the principal planes of curvature and under general skew-symmetric loading is considered. By employing a Reissner type shell theory which takes into account the effect of transverse shear strains, all boundary conditions on the crack surfaces are satisfied separately. Consequently, unlike those obtained from the classical shell theory, the angular distributions of the stress components around the crack tips are shown to be identical to the distributions obtained from the plane and antiplane elasticity solutions. Extensive results are given for axially and circumferentially cracked cylindrical shells, spherical shells, and toroidal shells under uniform inplane shearing, out of plane shearing, and torsion. The effect of orthotropy on the results is also studied.

  9. Thermal stresses in thick laminated composite shells

    NASA Technical Reports Server (NTRS)

    Yuan, F. G.

    1993-01-01

    The paper provides an analytical formulation to investigate the thermomechanical behavior of thick composite shells subjected to a temperature distribution which varies arbitrarily in the radial direction. For illustrative purposes, shells under uniform temperature change are presented. It is found that thermal twist would occur even for symmetric laminated shells. Under uniform temperature rise, results for off-axis graphite/epoxy shells show that extensional-shear coupling can cause tensile radial stress throughout the shell and tensile hoop stress in the inner region. Laminated graphite/epoxy shells can exhibit negative effective thermal expansion coefficients in the longitudinal and transverse directions. Finally, the stacking sequence has a strong influence on the thermal stress distributions.

  10. Mussel Shell Impaction in the Esophagus

    PubMed Central

    Kim, Sunmin; Kim, Hyung Hun; Jang, Gook Hwan; Song, Jun Young

    2013-01-01

    Mussels are commonly used in cooking around the world. The mussel shell breaks more easily than other shells, and the edge of the broken mussel shell is sharp. Impaction can ultimately cause erosion, perforation and fistula. Aside from these complications, the pain can be very intense. Therefore, it is essential to verify and remove the shell as soon as possible. In this report we describe the process of diagnosing and treating mussel shell impaction in the esophagus. Physicians can overlook this unusual foreign body impaction due to lack of experience. When physicians encounter a patient with severe chest pain after a meal with mussels, mussel shell impaction should be considered when diagnosing and treating the patient. PMID:23569440

  11. Flow past a porous approximate spherical shell

    NASA Astrophysics Data System (ADS)

    Srinivasacharya, D.

    2007-07-01

    In this paper, the creeping flow of an incompressible viscous liquid past a porous approximate spherical shell is considered. The flow in the free fluid region outside the shell and in the cavity region of the shell is governed by the Navier Stokes equation. The flow within the porous annulus region of the shell is governed by Darcy’s Law. The boundary conditions used at the interface are continuity of the normal velocity, continuity of the pressure and Beavers and Joseph slip condition. An exact solution for the problem is obtained. An expression for the drag on the porous approximate spherical shell is obtained. The drag experienced by the shell is evaluated numerically for several values of the parameters governing the flow.

  12. Shell boosts recovery at Kernridge

    SciTech Connect

    Moore, S.

    1984-01-01

    Since acquiring the Kernridge property in December 1979, Shell Oil Co. has drilled more than 1,800 wells and steadily increased production from 42,000 to 89,000 b/d of oil. Currently, the Kernridge Production Division of Shell California Production Inc. (SCPI), a newly formed subsidiary of Shell Oil Co., is operator for the property. The property covers approximately 35,000 mostly contiguous net acres, with production concentrated mainly on about 5,500 net acres. SCPI's four major fields in the area are the North and South Belridge, Lost Hills, and Antelope Hills. Most of the production comes from the North and South Belridge fields, which were previously held by the Belridge Oil Co. Productive horizons in the fields are the Tulare, Diatomite, Brown Shale, Antelope Shale, 64 Zone, and Agua sand. The Tulare and Diatomite are the two major reservoirs SCPI is developing. The Tulare, encountered between 400 and 1,300 ft, is made up of fine- to coarse-grained, unconsolidated sands with interbedded shales and silt stones and contains 13 /sup 0/ API oil. Using steam drive as the main recovery method, SCPI estimates an ultimate recovery from the Tulare formation of about 60% of the original 1 billion barrels in place. The Diatomite horizon, found between 800 and 3,500 ft and containing light, 28 /sup 0/ API oil, has high porosity (more than 60%), low permeability (less than 1 md), and natural fractures. Because of the Diatomite's low permeability, fracture stimulation is being used to increase well productivity. SCPI anticipates that approximately 5% of the almost 2 billion barrels of oil originally in place will be recovered by primary production.

  13. Boson shells harboring charged black holes

    SciTech Connect

    Kleihaus, Burkhard; Kunz, Jutta; Laemmerzahl, Claus; List, Meike

    2010-11-15

    We consider boson shells in scalar electrodynamics coupled to Einstein gravity. The interior of the shells can be empty space, or harbor a black hole or a naked singularity. We analyze the properties of these types of solutions and determine their domains of existence. We investigate the energy conditions and present mass formulae for the composite black hole-boson shell systems. We demonstrate that these types of solutions violate black hole uniqueness.

  14. Adaptive finite element strategies for shell structures

    NASA Technical Reports Server (NTRS)

    Stanley, G.; Levit, I.; Stehlin, B.; Hurlbut, B.

    1992-01-01

    The present paper extends existing finite element adaptive refinement (AR) techniques to shell structures, which have heretofore been neglected in the AR literature. Specific challenges in applying AR to shell structures include: (1) physical discontinuities (e.g., stiffener intersections); (2) boundary layers; (3) sensitivity to geometric imperfections; (4) the sensitivity of most shell elements to mesh distortion, constraint definition and/or thinness; and (5) intrinsic geometric nonlinearity. All of these challenges but (5) are addressed here.

  15. Characterization of Russian ballistic furnace shells

    SciTech Connect

    Fearon, E

    1999-02-18

    The authors received another batch of polystyrene ballistic furnace shells on December 4, 1998. Assigned the batch number of LSC012, it consisted of three cassettes containing 36 shells in each cassette. A group of 27 of the shells were selected for characterization that ranged in diameter from 1880 to 1780 {micro}m. There were two shells with a diameter above 1900 {micro}m, but they were too fragile and did not survive initial handling. For characterization, they examined the shells through a stereo microscope, measured diameter and sphericity on RACI, and weighed a subset of the 27 shells that did not have large particles or polymer shards adhered to the outside in order to calculate wall thickness. They then selected the cleanest and most spherical shells for Sphere Mapping. This batch of shells has about the same physical appearance as the one they documented August 26, 1998. There were some shells with polymer shards adhered to the outside, a few large vacuoles or large particle embedded in the polymer wall, and some with a scattering of small black particles on the outside. There were no swirls in the shell walls. As mentioned in the previous report, each shell is measured with the RACI system in three orthogonal views. They now have new analysis software on RACI that returns the mode two amplitude of the sphere radius vs. angle of rotation around the edge of the shadowgram of the shell. From this they report the maximum radius out-of-round, the largest of the three different orientations.

  16. Nanostructure and strain properties of core-shell GaAs/AlGaAs nanowires

    NASA Astrophysics Data System (ADS)

    Kehagias, Th; Florini, N.; Kioseoglou, J.; Pavloudis, Th; Komninou, Ph; Walther, T.; Moratis, K.; Hatzopoulos, Z.; Pelekanos, N. T.

    2015-11-01

    GaAs/AlGaAs core-shell nanowires (NWs) were grown on Si(111) by Ga-assisted molecular beam epitaxy via the vapor-liquid-solid mechanism. High-resolution and scanning transmission electron microscopy observations showed that NWs were predominantly zinc-blende single crystals of hexagonal shape, grown along the [111] direction. GaAs core NWs emerged from the Si surface and subsequently, the NW growth front advanced by a continuous sequence of (111) rotational twins, while the AlGaAs shell lattice was perfectly aligned with the core lattice. Occasionally, single or multiple stacking faults induced wurtzite structure NW pockets. The AlGaAs shell occupied at least half of the NW’s projected diameter, while the average Al content of the shell, estimated by energy dispersive x-ray analysis, was x = 0.35. Furthermore, molecular dynamics simulations of hexagonal cross-section NW slices, under a new parametrization of the Tersoff interatomic potential for AlAs, showed increased atom relaxation at the hexagon vertices of the shell. This, in conjunction with the compressively strained Al0.35Ga0.65As shell close to the GaAs core, can trigger a kinetic surface mechanism that could drive Al adatoms to accumulate at the relaxed sites of the shell, namely along the diagonals of the shell’s hexagon. Moreover, the absence of long-range stresses in the GaAs/Al0.35Ga0.65As core-shell system may account for a highly stable heterostructure. The latter was consolidated by temperature-dependent photoluminescence spectroscopy.

  17. Electron Shell as a Resonator

    NASA Astrophysics Data System (ADS)

    Karpeshin, F. F.

    2002-11-01

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

  18. Generic thin-shell gravastars

    SciTech Connect

    Martin-Moruno, Prado; Visser, Matt; Garcia, Nadiezhda Montelongo; Lobo, Francisco S.N. E-mail: nmontelongo@fis.cinvestav.mx E-mail: matt.visser@msor.vuw.ac.nz

    2012-03-01

    We construct generic spherically symmetric thin-shell gravastars by using the cut-and-paste procedure. We take considerable effort to make the analysis as general and unified as practicable; investigating both the internal physics of the transition layer and its interaction with 'external forces' arising due to interactions between the transition layer and the bulk spacetime. Furthermore, we discuss both the dynamic and static situations. In particular, we consider 'bounded excursion' dynamical configurations, and probe the stability of static configurations. For gravastars there is always a particularly compelling configuration in which the surface energy density is zero, while surface tension is nonzero.

  19. Celestial mechanics of planet shells

    NASA Astrophysics Data System (ADS)

    Barkin, Yu V.; Vilke, V. G.

    2004-06-01

    The motion of a planet consisting of an external shell (mantle) and a core (rigid body), which are connected by a visco-elastic layer and mutually gravitationally interact with each other and with an external celestial body (considered as a material point), is studied (Barkin, 1999, 2002a,b; Vilke, 2004). Relative motions of the core and mantle are studied on the assumption that the centres of mass of the planet and external body move on unperturbed Keplerian orbits around the general centre of mass of the system. The core and mantle of the planet have axial symmetry and have different principal moments of inertia. The differential action of the external body on the core and mantle cause the periodic relative displacements of their centres of mass and their relative turns. An approximate solution of the problem was obtained on the basis of the linearization, averaging and small-parameter methods. The obtained analytical results are applied to the study of the possible relative displacements of the core and mantle of the Earth under the gravitational action of the Moon. For the suggested two-body Earth model and in the simple case of a circular (model) lunar orbit the new phenomenon of periodic translatory-rotary oscillations of the core with a fortnightly period the mantle was observed. The more remarkable phenomenon is the cyclic rotation with the same period (13.7 days) of the core relative to the mantle with a ‘large’ amplitude of 152 m (at the core surface).The results obtained confirm the general concept described by Barkin (1999, 2002a,b) that induced relative shell oscillations can control and dictate the cyclic and secular processes of energization of the planets and satellites in definite rhythms and on different time scales.The results obtained mean that giant moments and forces produce energy which causes in particular deformations of the viscoelastic layer between planet shells. This process is realized with different intensities on different time

  20. Single Shell Tank (SST) Retrieval Sequence & Double Shell Tank (DST) Space Evaluation

    SciTech Connect

    HOHL, T.M.

    2001-09-20

    This document describes the baseline single-shell tank (SST) waste retrieval sequence for the River Protection Project updated for Fiscal Year 2002. The double-shell tank (DST) space evaluation presents projected DST needs for Hanford for additional DSTs.

  1. Single Shell Tank (SST) Retrieval Sequence and Double Shell Tank (DST) Space Evaluation

    SciTech Connect

    KIRCH, N.W.

    2003-09-23

    This document describes the baseline single-shell tank (SST) waste retrieval sequence for the River Protection Project updated for Fiscal Year 2002. The double-shell tank (DST) space evaluation presents projected DST needs for Hanford for additional DSTs.

  2. Single Shell Tank (SST) Retrieval Sequence & Double Shell Tank (DST) Space Evaluation

    SciTech Connect

    STRODE, J.N.

    2002-09-23

    This document describes the baseline single-shell tank (SST) waste retrieval sequence for the River Protection Project updated for Fiscal Year 2002. The double-shell tank (DST) space evaluation presents projected DST needs for Hanford for additional DSTs.

  3. Silver-silver oxide core-shell nanoparticles by femtosecond laser ablation: core and shell sizing by extinction spectroscopy

    NASA Astrophysics Data System (ADS)

    Schinca, D. C.; Scaffardi, L. B.; Videla, F. A.; Torchia, G. A.; Moreno, P.; Roso, L.

    2009-11-01

    The generation of small silver metal nanoparticles (Nps) by ultrashort pulsed laser ablation has been an active area of research in recent years due to their interest in several fields of applied research such as biotechnology and material research, in particular those with sizes smaller than 10 nm. In general, laser ablation tends to produce environmentally clean metal Nps compared with wet chemical methods. However, since silver may be oxidized in the presence of water or ethanol, core-shell silver-silver oxide (Ag-Ag2O) Nps can be formed, whose size and thickness must be determined and characterized for functionalization related to future applications. This work analyses the size characteristics of core-shell Ag-Ag2O colloid nanostructures (smaller than 10 nm) obtained by femtosecond laser ablation of solid silver targets in different liquid media (water or ethanol) through the study of their optical extinction spectra. A fit of full experimental spectrum using Mie theory allows the determination of core size and shell thickness distributions as a function of fluence. The red-shift of the plasmon peak wavelength with respect to the bare-core peak wavelength at 400 nm, produced by the oxide shell, may be easily measured even for very small thicknesses. It was found that the dominant Ag2O effective thickness is inversely proportional to the fluence, reaching a maximum of 0.2 nm for a fluence of 60 J cm-2 and a minimum of 0.04 nm for a fluence of 1000 J cm-2.

  4. Radiocarbon Dating: Fictitious Results with Mollusk Shells.

    PubMed

    Keith, M L; Anderson, G M

    1963-08-16

    Evidence is presented to show that modern mollusk shells from rivers can have anomalous radiocarbon ages, owing mainly to incorporation of inactive (carbon-14-deficient) carbon from humus, probably through the food web, as well as by the pathway of carbon dioxide from humus decay. The resultant effect, in addition to the variable contributions of atmospheric carbon dioxide, fermentative carbon dioxide from bottom muds, and, locally, of carbonate carbon from dissolving limestones, makes the initial carbon-14-activity of ancient fresh-water shell indeterminate, but within limits. Consequent errors of shell radiocarbon dates may be as large as several thousand years for river shells.

  5. Shell appraising deepwater discovery off Philippines

    SciTech Connect

    Scherer, M. ); Lambers, E.J.T.; Steffens, G.S. )

    1993-05-10

    Shell International Petroleum Co. Ltd. negotiated a farmout in 1990 from Occidental International Exploration and Production Co. for Block SC-38 in the South China Sea off Palawan, Philippines, following Oxy's discovery of gas in 1989 in a Miocene Nido limestone buildup. Under the terms of the farmout agreement, Shell became operator with a 50% share. Following the disappointing well North Iloc 1, Shell was successful in finding oil and gas in Malampaya 1. Water 700-1,000 m deep, remoteness, and adverse weather conditions have imposed major challenges for offshore operations. The paper describes the tectonic setting; the Nido limestone play; the Malampaya discovery; and Shell's appraisal studies.

  6. Thin-shell instability in collisionless plasma.

    PubMed

    Dieckmann, M E; Ahmed, H; Doria, D; Sarri, G; Walder, R; Folini, D; Bret, A; Ynnerman, A; Borghesi, M

    2015-09-01

    Thin-shell instability is one process which can generate entangled structures in astrophysical plasma on collisional (fluid) scales. It is driven by a spatially varying imbalance between the ram pressure of the inflowing upstream plasma and the downstream's thermal pressure at a nonplanar shock. Here we show by means of a particle-in-cell simulation that an analog process can destabilize a thin shell formed by two interpenetrating, unmagnetized, and collisionless plasma clouds. The amplitude of the shell's spatial modulation grows and saturates after about ten inverse proton plasma frequencies, when the shell consists of connected piecewise linear patches.

  7. Design optimization of a torpedo shell structure

    NASA Astrophysics Data System (ADS)

    Yu, De-Hai; Song, Bao-Wei; Li, Jia-Wang; Yang, Shi-Xing

    2008-03-01

    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.

  8. Material with core-shell structure

    DOEpatents

    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.

  9. Fracture Mitigation Strategies in Gastropod Shells

    NASA Astrophysics Data System (ADS)

    Salinas, Christopher; Kisailus, David

    2013-04-01

    For hundreds of millions of years, gastropods have been evolving, modifying their external calcified shells for defense against shell-breaking and drilling predators. They have evolved primarily to use two different aragonitic microstructures: the evolutionary older Nacre (mother of pearl) structure and the more recently developed crossed-lamellar structure. By using both of these structures, gastropods are able to produce shells that are significantly tougher then geologic aragonite. However, the crossed-lamellar structure allows for a wider variety of shell morphologies, ensuring its increasing presence since the Mesozoic Marine Revolution more than 200 million years ago.

  10. Archaeological Activity Report: Post-Review Discoveries Within 45BN431 at Solid Waste Site 128-F-2

    SciTech Connect

    T. E. Marceau; J. J. Sharpe

    2006-12-21

    During monitoring of remedial activities at Solid Waste Site 128-F-2 on August 19, 2005, a concentration of mussel shell was discovered in the west wall of a trench in the northen section of the waste site.

  11. Lead behavior in abalone shell

    NASA Astrophysics Data System (ADS)

    Hirao, Yoshimitsu; Matsumoto, Akikazu; Yamakawa, Hiroshi; Maeda, Masaru; Kimura, Kan

    1994-08-01

    In order to gain information about the behavior of heavy metals in biological assimilation processes in a marine food chain and to investigate the possibility that lead pollution in a marine environment can be estimated by measurement of a small number of key materials from such a food chain, muscle and shell were analyzed from abalone ( Haliotis) from a shallow water locality in a Japanese coastal region. Lead concentrations in muscle were about 26 ppb for abalone of approximately 3 years old and decreased systematically with increasing age of animals sampled, to about 3.3 ppb for a specimen approximately 8 years old. Lead concentrations in shell material gradually decreased also, from 150 ppb to 82 ppb in the oldest specimen. The decrease of concentration in tissues with increasing age indicates that a mechanism for exclusion of lead during tissue growth becomes more efficient with age. Along the food chain in which abalone is the final stage, lead was enriched at the first stage, from seawater to algae, by a factor of 100. Lead was diminished at all subsequent stages of the chain. Tissue of artificially cultured abalone had four times higher lead values compared to abalone grown in natural conditions, and this appears to reflect the fact that lead concentration was three times higher in seawater in the cultured environment.

  12. Transitional nuclei near shell closures

    SciTech Connect

    Mukherjee, G.

    2014-08-14

    High spin states in Bismuth and Thallium nuclei near the Z = 82 shell closure and Cesium nuclei near the N = 82 shell closure in A = 190 and A = 130 regions, respectively, have been experimentally investigated using heavy-ion fusion evaporation reaction and by detecting the gamma rays using the Indian National Gamma Array (INGA). Interesting shape properties in these transitional nuclei have been observed. The results were compared with the neighboring nuclei in these two regions. The total Routhian surface (TRS) calculations have been performed for a better understanding of the observed properties. In mass region A = 190, a change in shape from spherical to deformed has been observd around neutron number N = 112 for the Bi (Z = 83) isotopes with proton number above the magic gap Z = 82, whereas, the shape of Tl (Z = 81) isotopes with proton number below the magic gap Z = 82 remains stable as a function of neutron number. An important transition from aplanar to planar configuration of angular momentum vectors leading to the occurance of nuclar chirality and magnetic rotation, respectively, has been proposed for the unique parity πh{sub 11/2}⊗νh{sub 11/2} configuration in Cs isotopes in the mass region A ∼ 130 around neutron number N = 79. These results are in commensurate with the TRS calculations.

  13. Lead behavior in abalone shell

    SciTech Connect

    Hirao, Yoshimitsu; Matsumoto, Akikazu; Kimura, Kan ); Yamakawa, Hiroshi; Maeda, Masaru )

    1994-08-01

    In order to gain information about the behavior of heavy metals in biological assimilation processes in a marine food chain and to investigate the possibility that lead pollution in a marine environment can be estimated by measurement of a small number of key materials from such a food chain, muscle and shell were analyzed from abalone (Haliotis) from a shallow water locality in a Japanese coastal region. Lead concentrations in muscle were about 26 ppb for abalone approximately 3 years old and decreased systematically with increasing age of animals sampled, to about 3.3 ppb for a specimen approximately 8 years old. Lead concentrations in shell material gradually decreased also, from 150 ppb to 82 ppb in the oldest specimen. The decrease of concentration in tissues with increasing age indicates that a mechanism for exclusion of lead during tissue growth becomes more efficient with age. Along the food chain in which abalone is the final stage, lead was enriched at the first stage, from seawater to algae, by a factor of 100. Lead was diminished at all subsequent stages of the chain. Tissue of artificially cultured abalone had four times higher lead values compared to abalone grown in natural conditions, and this appears to reflect the fact that lead concentration was three times higher in seawater in the cultured environment.

  14. Apparatus and methods for installing, removing and adjusting an inner turbine shell section relative to an outer turbine shell section

    DOEpatents

    Leach, David; Bergendahl, Peter Allen; Waldo, Stuart Forrest; Smith, Robert Leroy; Phelps, Robert Kim

    2001-01-01

    A turbine includes upper and lower inner shell sections mounting the nozzles and shrouds and which inner shell is supported by pins secured to a surrounding outer shell. To disassemble the turbine for access to the inner shell sections and rotor, an alignment fixture is secured to the lower outer shell section and has pins engaging the inner shell section. To disassemble the turbine, the inner shell weight is transferred to the lower outer shell section via the alignment fixture and cradle pins. Roller assemblies are inserted through access openings vacated by support pins to permit rotation of the lower inner shell section out of and into the lower outer shell section during disassembly and assembly. The alignment fixture includes adjusting rods for adjusting the inner shell axially, vertically, laterally and about a lateral axis. A roller over-cage is provided to rotate the inner shell and a dummy shell to facilitate assembly and disassembly in the field.

  15. BV photometry of five shell galaxies

    NASA Astrophysics Data System (ADS)

    Pierfederici, F.; Rampazzo, R.

    2004-06-01

    Current views consider shell structures as bona fide signatures of a recent minor/major merging event though also weak interaction models (WIM) could produce long lasting shells on host galaxies possessing a stellar thick disc. We present a B V band photometric study of a sample of 5 shell galaxies belonging to the Malin & Carter (1983) compilation. The structural properties and colors of the galaxies, as well as the colors of their shells are examined in detail. We did not find signatures of the presence of double nuclei. NGC 7585 is the only E galaxy in the sample and has a moderately boxy structure. The other galaxies have either a discy structure or are mixed E/S0 type galaxies. NGC 474 is a true lenticular. NGC 6776 shows a diffuse asymmetric outer structure and a system of tails of the the same color of the galaxy body; but not clear shells. In general, the color of the shells in our sample is similar or slightly redder than that of the host galaxy, whose color, in turn, is typical of the early-type morphological class. One of the outer shells of NGC 474 is significantly bluer than the body of the galaxy. Since NGC 474 appears to be interacting with NGC 470, the color of this one shell could be explained as result of a recent acquisition of material through tidal interaction. The WIM hypothesis could explain both the red and the blue shells of NGC 474, this latter acquired from the fly-by of the nearby companion NGC 470, but the lack of the constancy of shell surface brightness as a ratio of the underlying galaxy brightness argues against WIM. We speculate about evidence, which also comes from different observations, that suggests a merging/accretion origin of the shells. Based on observations obtained at the Observatoire de Haute Provence, CNRS, Saint Michel l'Observatoire, France and ESO, La Silla, Chile

  16. Synthesis of 3D Printable Cu-Ag Core-Shell Materials: Kinetics of CuO Film Removal

    NASA Astrophysics Data System (ADS)

    Hong, Seongik; Kim, Namsoo

    2015-03-01

    In this research, Cu-Ag core-shell particles were synthesized as a functional and 3D printable material. Using the solid-liquid method, Cu-Ag core-shell particles were simply synthesized, and different particle sizes of 100 nm and 2 μm were used to confirm the size effect in the synthesis and reaction control of the Cu-Ag core-shell particles. In addition, highly viscous Cu-Ag core-shell particle paste was also prepared, and its electrical conductivity was measured. As a result, the reaction rate in the case of the 2 μm Cu particles was controlled by film diffusion, whereas for the 100 nm Cu particles, the reaction rate was controlled by CuO film produced before reacting with Ag ions in solution, and limited by chemical reaction control. Through the solid-liquid method, dendrite-shaped Cu-Ag core-shell particles were formed. Also, the electrical conductivity increased with increasing sintering temperature and core-shell particle concentration.

  17. The ultimate step towards a tailored engineering of core@shell and core@shell@shell nanoparticles.

    PubMed

    Llamosa, D; Ruano, M; Martínez, L; Mayoral, A; Roman, E; García-Hernández, M; Huttel, Y

    2014-11-21

    Complex core@shell and core@shell@shell nanoparticles are systems that combine the functionalities of the inner core and outer shell materials together with new physico-chemical properties originated by their low (nano) dimensionality. Such nanoparticles are of prime importance in the fast growing field of nanotechnology as building blocks for more sophisticated systems and a plethora of applications. Here, it is shown that although conceptually simple a modified gas aggregation approach allows the one-step generation of well-controlled complex nanoparticles. In particular, it is demonstrated that the atoms of the core and the shell of the nanoparticles can be easily inverted, avoiding intrinsic constraints of chemical methods.

  18. Heterogeneous core/shell fluoride nanocrystals with enhanced upconversion photoluminescence for in vivo bioimaging.

    PubMed

    Hao, Shuwei; Yang, Liming; Qiu, Hailong; Fan, Rongwei; Yang, Chunhui; Chen, Guanying

    2015-06-28

    We report on heterogeneous core/shell CaF2:Yb(3+)/Ho(3+)@NaGdF4 nanocrystals of 17 nm with efficient upconversion (UC) photoluminescence (PL) for in vivo bioimaging. Monodisperse core/shell nanostructures were synthesized using a seed-mediated growth process involving two quite different approaches of liquid-solid-solution and thermal decomposition. They exhibit green emission with a sharp band around 540 nm when excited at ∼980 nm, which is about 39 times brighter than the core CaF2:Yb(3+)/Ho(3+) nanoparticles. PL decays at 540 nm revealed that such an enhancement arises from efficient suppression of surface-related deactivation from the core nanocrystals. In vivo bioimaging employing water-dispersed core/shell nanoparticles displayed high contrast against the background. PMID:26035440

  19. Isothermal Circumstellar Dust Shell Model for Teaching

    ERIC Educational Resources Information Center

    Robinson, G.; Towers, I. N.; Jovanoski, Z.

    2009-01-01

    We introduce a model of radiative transfer in circumstellar dust shells. By assuming that the shell is both isothermal and its thickness is small compared to its radius, the model is simple enough for students to grasp and yet still provides a quantitative description of the relevant physical features. The isothermal model can be used in a…

  20. A Geometric Theory of Nonlinear Morphoelastic Shells

    NASA Astrophysics Data System (ADS)

    Sadik, Souhayl; Angoshtari, Arzhang; Goriely, Alain; Yavari, Arash

    2016-08-01

    Many thin three-dimensional elastic bodies can be reduced to elastic shells: two-dimensional elastic bodies whose reference shape is not necessarily flat. More generally, morphoelastic shells are elastic shells that can remodel and grow in time. These idealized objects are suitable models for many physical, engineering, and biological systems. Here, we formulate a general geometric theory of nonlinear morphoelastic shells that describes both the evolution of the body shape, viewed as an orientable surface, as well as its intrinsic material properties such as its reference curvatures. In this geometric theory, bulk growth is modeled using an evolving referential configuration for the shell, the so-called material manifold. Geometric quantities attached to the surface, such as the first and second fundamental forms, are obtained from the metric of the three-dimensional body and its evolution. The governing dynamical equations for the body are obtained from variational consideration by assuming that both fundamental forms on the material manifold are dynamical variables in a Lagrangian field theory. In the case where growth can be modeled by a Rayleigh potential, we also obtain the governing equations for growth in the form of kinetic equations coupling the evolution of the first and the second fundamental forms with the state of stress of the shell. We apply these ideas to obtain stress-free growth fields of a planar sheet, the time evolution of a morphoelastic circular cylindrical shell subject to time-dependent internal pressure, and the residual stress of a morphoelastic planar circular shell.

  1. An egg shell-like retroperitoneal pseudocyst.

    PubMed

    Li, Zhao-Lun; Li, Hong-Liang; Chen, Hai-Weng; Gan, Wei-Ming

    2011-09-01

    Retroperitoneal pseudocysts are rare entities. Egg shell-like calcified retroperitoneal pseudocyst is rarer. We report a 75-year-old woman with an egg shell-like calcified retroperitoneal pseudocyst. Subsequently, the calcified pseudocyst was dissected and excised completely through laparoscopy via a retroperitoneal approach.

  2. A Well-Defined Bipolar Outflow Shell

    NASA Astrophysics Data System (ADS)

    Xie, Taoling; Goldsmith, Paul F.; Patel, Nimesh

    1992-12-01

    A well-defined "eggplant-shaped" thin shell is revealed in the Mon R2 central core region by CO and (13) CO J=1-0 maps obtained with QUARRY. This thin shell outlines the extended blue lobe of the massive bipolar outflow. The projected length and width of the shell are about 5.7 pc and 2.5 pc respectively, and the averaged projected thickness of the shell is ~ 0.3 pc. The shape of this shell can be satisfactorily accounted for quantitatively in terms of limb-brightening within the framework of the Shu et al shell model with radially directed wind, although the model seems to be oversimplified with respect to the complexity that our data reveal. The outflow shell's symmetry axis is estimated to be inclined by ~ 70(deg) with respect to the line of sight. We suggest that the coincident blue- and red-shifted emission and the bending of the red-shifted lobe are the result of the red-shifted shell being compressed, rather than having a second bipolar outflow aligned roughly perpendicular to the axis of the first bipolar outflow.

  3. The wavefunction of a gravitating shell

    SciTech Connect

    Dokuchaev, V. I. Chernov, S. V.

    2010-10-15

    We have calculated a discrete spectrum and found an exact analytical solution in the form of Meixner polynomials for the wavefunction of a thin gravitating shell in the Reissner-Nordstroem geometry. We show that there is no extreme state in the quantum spectrum of the gravitating shell, as in the case of an extreme black hole.

  4. Thick-shell nanocrystal quantum dots

    DOEpatents

    Hollingsworth, Jennifer A.; Chen, Yongfen; Klimov, Victor I.; Htoon, Han; Vela, Javier

    2011-05-03

    Colloidal nanocrystal quantum dots comprising an inner core having an average diameter of at least 1.5 nm and an outer shell, where said outer shell comprises multiple monolayers, wherein at least 30% of the quantum dots have an on-time fraction of 0.80 or greater under continuous excitation conditions for a period of time of at least 10 minutes.

  5. Biomineral repair of abalone shell apertures.

    PubMed

    Cusack, Maggie; Guo, Dujiao; Chung, Peter; Kamenos, Nicholas A

    2013-08-01

    The shell of the gastropod mollusc, abalone, is comprised of nacre with an outer prismatic layer that is composed of either calcite or aragonite or both, depending on the species. A striking characteristic of the abalone shell is the row of apertures along the dorsal margin. As the organism and shell grow, new apertures are formed and the preceding ones are filled in. Detailed investigations, using electron backscatter diffraction, of the infill in three species of abalone: Haliotis asinina, Haliotis gigantea and Haliotis rufescens reveals that, like the shell, the infill is composed mainly of nacre with an outer prismatic layer. The infill prismatic layer has identical mineralogy as the original shell prismatic layer. In H. asinina and H. gigantea, the prismatic layer of the shell and infill are made of aragonite while in H. rufescens both are composed of calcite. Abalone builds the infill material with the same high level of biological control, replicating the structure, mineralogy and crystallographic orientation as for the shell. The infill of abalone apertures presents us with insight into what is, effectively, shell repair.

  6. A Shell/3D Modeling Technique for Delaminations in Composite Laminates

    NASA Technical Reports Server (NTRS)

    Krueger, Ronald

    1999-01-01

    A shell/3D modeling technique was developed for which a local solid finite element model is used only in the immediate vicinity of the delamination front. The goal was to combine the accuracy of the full three-dimensional solution with the computational efficiency of a plate or shell finite element model. Multi-point constraints provide a kinematically compatible interface between the local 3D model and the global structural model which has been meshed with plate or shell finite elements. For simple double cantilever beam (DCB), end notched flexure (ENF), and single leg bending (SLB) specimens, mixed mode energy release rate distributions were computed across the width from nonlinear finite element analyses using the virtual crack closure technique. The analyses served to test the accuracy of the shell/3D technique for the pure mode I case (DCB), mode II case (ENF) and a mixed mode I/II case (SLB). Specimens with a unidirectional layup where the delamination is located between two 0 plies, as well as a multidirectional layup where the delamination is located between two non-zero degree plies, were simulated. For a local 3D model extending to a minimum of about three specimen thicknesses in front of and behind the delamination front, the results were in good agreement with mixed mode strain energy release rates obtained from computations where the entire specimen had been modeled with solid elements. For large built-up composite structures modeled with plate elements, the shell/3D modeling technique offers a great potential, since only a relatively small section in the vicinity of the delamination front needs to be modeled with solid elements.

  7. Ecology and shell chemistry of Loxoconcha matagordensis

    USGS Publications Warehouse

    Cronin, T. M.; Kamiya, T.; Dwyer, G.S.; Belkin, H.; Vann, C.D.; Schwede, S.; Wagner, R.

    2005-01-01

    Studies of the seasonal ecology and shell chemistry of the ostracode Loxoconcha matagordensis and related species of Loxoconcha from regions off eastern North America reveal that shell size and trace elemental (Mg/Ca ratio) composition are useful in paleothermometry using fossil populations. Seasonal sampling of populations from Chesapeake Bay, augmented by samples from Florida Bay, indicate that shell size is inversely proportional to water temperature and that Mg/Ca ratios are positively correlated with the water temperature in which the adult carapace was secreted. Microprobe analyses of sectioned valves reveal intra-shell variability in Mg/Ca ratios but this does not strongly influence the utility of whole shell Mg/Ca analyses for paleoclimate application.

  8. The Vega particulate shell - Comets or asteroids?

    NASA Technical Reports Server (NTRS)

    Weissman, P. R.

    1984-01-01

    The Infrared Astronomical Satellite (IRAS) science team has discovered a shell of particulate material around the star Vega. At the mean distance and temperature of the shell, the expected condensation products from a protostellar nebula would be dominated by frozen volatiles, in particular water ice. It is not possible to discriminate between dirty ice and silicate materials in the Vega shell on the basis of the IRAS data. The Vega shell is probably a ring of cometary bodies with an estimated minimum mass of 15 earth masses, analogous to one that has been hypothesized for the solar system. A possible hot inner shell around Vega may be an asteroid-like belt of material a few astronomical units from the star.

  9. Variability in shell models of GRBs

    SciTech Connect

    Sumner, M.C.; Fenimore, E.E.

    1997-09-01

    Many cosmological models of gamma-ray bursts (GRBs) assume that a single relativistic shell carries kinetic energy away from the source and later converts it into gamma rays, perhaps by interactions with the interstellar medium or by internal shocks within the shell. Although such models are able to reproduce general trends in GRB time histories, it is difficult to reproduce the high degree of variability often seen in GRBs. The authors investigate methods of achieving this variability using a simplified external shock model. Since the model emphasizes geometric and statistical considerations, rather than the detailed physics of the shell, it is applicable to any theory that relies on relativistic shells. They find that the variability in GRBs gives strong clues to the efficiency with which the shell converts its kinetic energy into gamma rays.

  10. Semiclassical shell structure in rotating Fermi systems

    SciTech Connect

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

    2010-06-15

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

  11. Engineered Magnetic Core-Shell Structures.

    PubMed

    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. PMID:26377655

  12. The protein shells of bacterial microcompartment organelles

    PubMed Central

    Yeates, Todd O.; Thompson, Michael C.; Bobik, Thomas A.

    2011-01-01

    SUMMARY Details are emerging on the structure and function of a remarkable class of capsid-like protein assemblies that serve as simple metabolic organelles in many bacteria. These bacterial microcompartments consist of a few thousand shell proteins, which encapsulate two or more sequentially acting enzymes in order to enhance or sequester certain metabolic pathways, particularly those involving toxic or volatile intermediates. Genomic data indicate that bacterial microcompartment shell proteins are present in a wide range of bacterial species, where they encapsulate varied reactions. Crystal structures of numerous shell proteins from distinct types of microcompartments have provided keys for understanding how the shells are assembled and how they conduct molecular transport into and out of microcompartments. The structural data emphasize a high level of mechanistic sophistication in the protein shell, and point the way for further studies on this fascinating but poorly appreciated class of subcellular structures. PMID:21315581

  13. Thermal equilibrium in Europa's ice shell

    NASA Astrophysics Data System (ADS)

    Moore, William B.

    2006-01-01

    Models of tidal-convective equilibrium for Europa's ice shell are computed using a laboratory-derived composite flow law for ice. Volume diffusion creep is found to dominate the flow law at equilibrium, and thus the thickness of the shell is strongly dependent on the poorly known grain size of the ice. This grain size is, however, constrained to be less than a few millimeters if equilibrium is achieved at the current eccentricity. Europa's ice shell cannot be thinner than about 16 km in equilibrium at present, since tidal dissipation cannot generate enough heat in such a thin shell to balance the heat transport. No conductive equilibria are found; this is likely due to the fact that most of a conductive shell must be cold if temperature gradients are to be large enough to carry the heat. A minimum eccentricity of about 0.0025 (about 1/4 the present value) below which there are no equilibria is also found.

  14. The vega particulate shell: comets or asteroids?

    PubMed

    Weissman, P R

    1984-06-01

    The Infrared Astronomical Satellite (IRAS) science team has discovered a shell of particulate material around the star Vega. At the mean distance and temperature of the shell, the expected condensation products from a protostellar nebula would be dominated by frozen volatiles, in particular water ice. It is not possible to discriminate between dirty ice and silicate materials in the Vega shell on the basis of the IRAS data. The Vega shell is probably a ring of cometary bodies with an estimated minimum mass of 15 earth masses, analogous to one that has been hypothesized for the solar system. A possible hot inner shell around Vega may be an asteroid-like belt of material a few astronomical units from the star. PMID:17731997

  15. Application of the Shell/3D Modeling Technique for the Analysis of Skin-Stiffener Debond Specimens

    NASA Technical Reports Server (NTRS)

    Krueger, Ronald; O'Brien, T. Kevin; Minguet, Pierre J.

    2002-01-01

    The application of a shell/3D modeling technique for the simulation of skin/stringer debond in a specimen subjected to three-point bending is demonstrated. The global structure was modeled with shell elements. A local three-dimensional model, extending to about three specimen thicknesses on either side of the delamination front was used to capture the details of the damaged section. Computed total strain energy release rates and mixed-mode ratios obtained from shell/13D simulations were in good agreement with results obtained from full solid models. The good correlations of the results demonstrated the effectiveness of the shell/3D modeling technique for the investigation of skin/stiffener separation due to delamination in the adherents.

  16. Electroformation of uranium hemispherical shells

    SciTech Connect

    Marshall, S.L.; Redey, L.; Vandegrift, G.F.; Vissers, D.R.

    1989-11-01

    This effort was directed at developing an electrochemical process for forming uniform and dendrite-free deposits of uranium from molten salts. This process is to be used for the electroformation of free-standing hemispherical shells of uranium for nuclear applications. Electrodeposition of uranium onto a substrate was accomplished with a fused chloride mixture containing 42 wt% UCl{sub 3} and a fused chloride-fluoride mixture containing 4 wt % UF{sub 4}. Under pulsed potential control at 504{degree}C, the chloride-fluoride mixture yielded the widest range of plating conditions for which dendrites could be avoided. Bipolar current pulse plating with both electrolytes gave good results, and successful application of this technique to a large tubular cathode has been demonstrated. 24 refs., 10 figs.

  17. Spherical-shell model for the van der Waals coefficients between fullerenes and/or nearly spherical nanoclusters.

    PubMed

    Perdew, John P; Tao, Jianmin; Hao, Pan; Ruzsinszky, Adrienn; Csonka, Gábor I; Pitarke, J M

    2012-10-24

    Fullerene molecules such as C(60) are large nearly spherical shells of carbon atoms. Pairs of such molecules have a strong long-range van der Waals attraction that can produce scattering or binding into molecular crystals. A simplified classical-electrodynamics model for a fullerene is a spherical metal shell, with uniform electron density confined between outer and inner radii (just as a simplified model for a nearly spherical metallic nanocluster is a solid metal sphere or filled shell). For the spherical-shell model, the exact dynamic multipole polarizabilities are all known analytically. From them, we can derive exact analytic expressions for the van der Waals coefficients of all orders between two spherical metal shells. The shells can be identical or different, and hollow or filled. To connect the model to a real fullerene, we input the static dipole polarizability, valence electron number and estimated shell thickness t of the real molecule. Our prediction for the leading van der Waals coefficient C(6) between two C(60) molecules ((1.30 ± 0.22) × 10(5) hartree bohr(6)) agrees well with a prediction for the real molecule from time-dependent density functional theory. Our prediction is remarkably insensitive to t. Future work might include the prediction of higher-order (e.g. C(8) and C(10)) coefficients for C(60), applications to other fullerenes or nearly spherical metal clusters, etc. We also make general observations about the van der Waals coefficients.

  18. Shell middle distillate hydrogenation process

    SciTech Connect

    Lucien, J.P.; Berg, J.P. van den; Hooijdonk, H.M.J.H. van; Thielemans, G.L.B.; Germaine, G.; Gjers, M.

    1994-12-31

    The strive towards cleaner environment has lead to low sulfur specifications for middle distillate fuels. In addition compositional specifications are presently debated. Thus, to meet future emissions standards regarding, specifically, particulates emissions, the motor industry calls for improved automotive gasoil quality. Although automotive gasoil quality affects emissions from diesel engines it is considered less influential than engine design and maintenance. Sulfur, density and cetane number are the fuel properties having the greatest influence on diesel engine emissions although also aromatics and endpoint specifications have been defined in environmentally adopted government initiatives. This paper reviews the options which are available to tackle these new requirements. The high severity single stage concept (using conventional mixed sulfides catalysts) will be discussed in its potential to meet more severe product requirements as well as in terms of its limitations, especially at the point of aromatics saturation and cetaine upgrading. Furthermore, it is shown that the option of severe hydrotreating followed by hydrogenation with conventional noble metal catalysts is preferred if deep aromatics saturation is aimed at. However, this conventional two stage concept has limitations with respect to heaviness and sulfur and nitrogen content of feedstocks. The new Shell Middle Distillate Hydrogenation (SMDH) technology, applying a (semi) two stage approach based on the Shell developed hydrogenation catalyst is presented. The SMDH process will be discussed in its potential to break the limitations of the conventional options. The new catalyst is crucial in this process and allows a highly integrated mode of operation. A number of applications of this novel process will be discussed.

  19. Facile one-pot synthesis of multi-yolk-shell Bi@C nanostructures by the nanoscale Kirkendall effect.

    PubMed

    Cui, C M; Guo, X H; Geng, Y M; Dang, T T; Xie, G; Chen, S P; Zhao, F Q

    2015-06-01

    Multi-yolk-shell Bi@C nanostructures were prepared via a facile one-pot template-free hydrothermal approach. The prepared Bi@C nanostructures can act as a solid catalyst in the thermal decomposition of cyclotrimethylenetrinitramine (RDX) and display excellent catalytic activity, which highlights their application in the field of energetic materials.

  20. Development of a particle nanoimprinting technique by core-shell particles.

    PubMed

    Watanabe, H; Nishimura, M; Fukui, Y; Fujimoto, K

    2014-02-18

    We developed a particle nanoimprinting technique assisted by the array of core-shell particles. Core-shell particles composed of a solid core of polystyrene and a soft shell were prepared by soap-free emulsion polymerization and subsequently seeded polymerization. By the Langmuir-Blodgett method, particles were arranged into a closely packed 2D array over the water surface and transferred onto a polystyrene (PS) substrate at a regular interval. The PS substrate was heated up above its glass transition temperature (Tg) by either UV irradiation using a high-pressure Hg lamp or heat treatment in a temperature-controlled incubator. It could be observed that a nanopatterned indented surface was formed through the denting of particles into the PS substrate (particle nanoindenting). By the detachment of particles from the substrate by ultrasonication in ethanol, nanoholes were produced over the surface (particle nanoimprinting). The depth and the wall of nanoholes and their interval were tunable by the shell thickness and the 2D packing ratio of core-shell particle monolayers. The contact angle decreased from 70 degrees of the pristine particle monolayer to 13 degrees by the particle nanoindenting, and again increased to 50 degrees by detaching the particles from the substrate to create the nanoholes. The use of nanoholes as zepto-litter volume vessels enabled us to produce and arrange nanocrystals, such as NaCl and CaCO3 (zepto-reactor).

  1. Single-crystal apatite nanowires sheathed in graphitic shells: synthesis, characterization, and application.

    PubMed

    Jeong, Namjo; Cha, Misun; Park, Yun Chang; Lee, Kyung Mee; Lee, Jae Hyup; Park, Byong Chon; Lee, Junghoon

    2013-07-23

    Vertically aligned one-dimensional hybrid structures, which are composed of apatite and graphitic structures, can be beneficial for orthopedic applications. However, they are difficult to generate using the current method. Here, we report the first synthesis of a single-crystal apatite nanowire encapsulated in graphitic shells by a one-step chemical vapor deposition. Incipient nucleation of apatite and its subsequent transformation to an oriented crystal are directed by derived gaseous phosphorine. Longitudinal growth of the oriented apatite crystal is achieved by a vapor-solid growth mechanism, whereas lateral growth is suppressed by the graphitic layers formed through arrangement of the derived aromatic hydrocarbon molecules. We show that this unusual combination of the apatite crystal and the graphitic shells can lead to an excellent osteogenic differentiation and bony fusion through a programmed smart behavior. For instance, the graphitic shells are degraded after the initial cell growth promoted by the graphitic nanostructures, and the cells continue proliferation on the bare apatite nanowires. Furthermore, a bending experiment indicates that such core-shell nanowires exhibited a superior bending stiffness compared to single-crystal apatite nanowires without graphitic shells. The results suggest a new strategy and direction for bone grafting materials with a highly controllable morphology and material conditions that can best stimulate bone cell differentiation and growth. PMID:23755838

  2. Resonance frequencies of lipid-shelled microbubbles in the regime of nonlinear oscillations

    PubMed Central

    Doinikov, Alexander A.; Haac, Jillian F.; Dayton, Paul A.

    2009-01-01

    Knowledge of resonant frequencies of contrast microbubbles is important for the optimization of ultrasound contrast imaging and therapeutic techniques. To date, however, there are estimates of resonance frequencies of contrast microbubbles only for the regime of linear oscillation. The present paper proposes an approach for evaluating resonance frequencies of contrast agent microbubbles in the regime of nonlinear oscillation. The approach is based on the calculation of the time-averaged oscillation power of the radial bubble oscillation. The proposed procedure was verified for free bubbles in the frequency range 1–4 MHz and then applied to lipid-shelled microbubbles insonified with a single 20-cycle acoustic pulse at two values of the acoustic pressure amplitude, 100 kPa and 200 kPa, and at four frequencies: 1.5, 2.0, 2.5, and 3.0 MHz. It is shown that, as the acoustic pressure amplitude is increased, the resonance frequency of a lipid-shelled microbubble tends to decrease in comparison with its linear resonance frequency. Analysis of existing shell models reveals that models that treat the lipid shell as a linear viscoelastic solid appear may be challenged to provide the observed tendency in the behavior of the resonance frequency at increasing acoustic pressure. The conclusion is drawn that the further development of shell models could be improved by the consideration of nonlinear rheological laws. PMID:18977009

  3. Au-Cu{sub 2}O core-shell nanowire photovoltaics

    SciTech Connect

    Oener, S. Z.; Mann, S. A.; Sciacca, B.; Sfiligoj, C.; Hoang, J.; Garnett, E. C.

    2015-01-12

    Semiconductor nanowires are among the most promising candidates for next generation photovoltaics. This is due to their outstanding optical and electrical properties which provide large optical cross sections while simultaneously decoupling the photon absorption and charge carrier extraction length scales. These effects relax the requirements for both the minority carrier diffusion length and the amount of semiconductor needed. Metal-semiconductor core-shell nanowires have previously been predicted to show even better optical absorption than solid semiconductor nanowires and offer the additional advantage of a local metal core contact. Here, we fabricate and analyze such a geometry using a single Au-Cu{sub 2}O core-shell nanowire photovoltaic cell as a model system. Spatially resolved photocurrent maps reveal that although the minority carrier diffusion length in the Cu{sub 2}O shell is less than 1 μm, the radial contact geometry with the incorporated metal electrode still allows for photogenerated carrier collection along an entire nanowire. Current-voltage measurements yield an open-circuit voltage of 600 mV under laser illumination and a dark diode turn-on voltage of 1 V. This study suggests the metal-semiconductor core-shell nanowire concept could be extended to low-cost, large-scale photovoltaic devices, utilizing for example, metal nanowire electrode grids coated with epitaxially grown semiconductor shells.

  4. Development of a particle nanoimprinting technique by core-shell particles.

    PubMed

    Watanabe, H; Nishimura, M; Fukui, Y; Fujimoto, K

    2014-02-18

    We developed a particle nanoimprinting technique assisted by the array of core-shell particles. Core-shell particles composed of a solid core of polystyrene and a soft shell were prepared by soap-free emulsion polymerization and subsequently seeded polymerization. By the Langmuir-Blodgett method, particles were arranged into a closely packed 2D array over the water surface and transferred onto a polystyrene (PS) substrate at a regular interval. The PS substrate was heated up above its glass transition temperature (Tg) by either UV irradiation using a high-pressure Hg lamp or heat treatment in a temperature-controlled incubator. It could be observed that a nanopatterned indented surface was formed through the denting of particles into the PS substrate (particle nanoindenting). By the detachment of particles from the substrate by ultrasonication in ethanol, nanoholes were produced over the surface (particle nanoimprinting). The depth and the wall of nanoholes and their interval were tunable by the shell thickness and the 2D packing ratio of core-shell particle monolayers. The contact angle decreased from 70 degrees of the pristine particle monolayer to 13 degrees by the particle nanoindenting, and again increased to 50 degrees by detaching the particles from the substrate to create the nanoholes. The use of nanoholes as zepto-litter volume vessels enabled us to produce and arrange nanocrystals, such as NaCl and CaCO3 (zepto-reactor). PMID:24446687

  5. Empirical calibration of shell chemistry of Cyprideis torosa (Jones, 1850) (Crustacea: Ostracoda)

    NASA Astrophysics Data System (ADS)

    Marco-Barba, J.; Ito, E.; Carbonell, E.; Mesquita-Joanes, F.

    2012-09-01

    Cyprideis torosa is a species of ostracode that inhabits a wide range of aquatic habitats in which its low Alk/Ca requirement is met. Its fossil remains are widely used in palaeoecological studies of coastal environments and inland salt lakes. We collected C. torosa from 20 water bodies near Valencia, Spain. Temperature, chlorophyll a concentration, electrical conductivity, and the concentration of major ions and oxygen isotopes were measured at each site. Between 2 and 20 live individuals of C. torosa were collected per site, their instar stage and sex determined and their shell chemistry (Mg/Ca, Sr/Ca and carbon and oxygen isotope composition) analyzed. Three of these sites were sampled monthly for one year, and ostracode population structure and shell chemistry (20-40 shells) were analyzed. The water chemistry varied widely between sites. TDS (total dissolved solids) ranged from 0.5 to 71.8 g/L but chloride was always the dominant anion. There is a significant positive relationship between ostracode and water δ18O except at high TDS (>20 g/L) when shell δ18O values are lower than expected. No effect of either temperature or water Mg/Ca is observed on the Mg/Ca in the ostracode calcite in waters with Mg/Ca < 6 (molar ratio). Ostracode shell Sr/Ca is strongly and significantly related to water Sr/Ca. δ13C values in C. torosa shells are ˜2‰ lower than observed δ13CDIC. These results provide new and more accurate quantification tools to reconstruct past hydrochemistry from C. torosa shells.

  6. Synthesis of Zeolitic Imidazolate Framework Core-Shell Nanosheets Using Zinc-Imidazole Pseudopolymorphs.

    PubMed

    Lee, Wan-Chi; Chien, Heng-Ta; Lo, Yang; Chiu, Hao-Che; Wang, Tung-Ping; Kang, Dun-Yen

    2015-08-26

    Zeolitic imidazolate frameworks (ZIFs) are an emerging class of microporous materials that possess an organic flexible scaffold and zeolite-like topology. The catalytic and molecular-separation capabilities of these materials have attracted considerable attention; however, crystal-shape engineering in ZIF materials remains in its infancy. This is the first study to report an effective method for tailoring the near-spherical crystal morphology of ZIF-8 using its leaf-like pseudopolymorph, ZIF-L. A thin, uniform layer of ZIF-8 is formed on ZIF-L through heterogeneous surface growth to produce a ZIF-L@ZIF-8 core-shell nanocomposite. This results in ZIF-8 with a crystal morphology comprising two-dimensional nanoflakes. We characterized the resulting core-shell crystals using a number of solid-state techniques, including powder X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, and nitrogen physisorption. Approximately 16 mass% of ZIF-8 in the core-shell composites heterogeneous surfacely grown on ZIF-L core crystals. We also investigated the effects of zinc salts, which were used as a source of zinc in the formation of the ZIF-L@ZIF-8 core-shell nanocomposites. Finally, we assessed the CO2 adsorption properties of ZIF-8, ZIF-L, and ZIF-L@ZIF-8 core-shell crystals, the results of which were used to deduce the dynamic and equilibrium adsorption characteristics of various microporous ZIF crystals. The core-shell materials present hybridized CO2 uptake and diffusivity of the parent crystals. The proposed method for the synthesis of core-shell nanocomposites using pseudopolymorphic crystals is applicable to other ZIF systems.

  7. Process-Dependent Properties in Colloidally Synthesized “Giant” Core/Shell Nanocrystal Quantum Dots

    SciTech Connect

    Hollingsworth, Jennifer A.; Ghosh, Yagnaseni; Dennis, Allison M.; Mangum, Benjamin D.; Park, Young-Shin; Kundu, Janardan; Htoon, Han

    2012-06-07

    Due to their characteristic bright and stable photoluminescence, semiconductor nanocrystal quantum dots (NQDs) have attracted much interest as efficient light emitters for applications from single-particle tracking to solid-state lighting. Despite their numerous enabling traits, however, NQD optical properties are frustratingly sensitive to their chemical environment, exhibit fluorescence intermittency ('blinking'), and are susceptible to Auger recombination, an efficient nonradiative decay process. Previously, we showed for the first time that colloidal CdSe/CdS core/shell nanocrystal quantum dots (NQDs) comprising ultrathick shells (number of shell monolayers, n, > 10) grown by protracted successive ionic layer adsorption and reaction (SILAR) leads to remarkable photostability and significantly suppressed blinking behavior as a function of increasing shell thickness. We have also shown that these so-called 'giant' NQDs (g-NQDs) afford nearly complete suppression of non-radiative Auger recombination, revealed in our studies as long biexciton lifetimes and efficient multiexciton emission. The unique behavior of this core/shell system prompted us to assess correlations between specific physicochemical properties - beyond shell thickness - and functionality. Here, we demonstrate the ability of particle shape/faceting, crystalline phase, and core size to determine ensemble and single-particle optical properties (quantum yield/brightness, blinking, radiative lifetimes). Significantly, we show how reaction process parameters (surface-stabilizing ligands, ligand:NQD ratio, choice of 'inert' solvent, and modifications to the SILAR method itself) can be tuned to modify these function-dictating NQD physical properties, ultimately leading to an optimized synthetic approach that results in the complete suppression of blinking. We find that the resulting 'guiding principles' can be applied to other NQD compositions, allowing us to achieve non-blinking behavior in the near

  8. Hierarchical Structure of Lattices in Film Formation of Core-Shell Type Polymer Microspheres

    PubMed

    Saito; Sugita; Ishizu

    1997-03-15

    By adding polystyrene homopolymer in the solid state, super-lattice structures of poly(4-vinyl pyridine) core-polystyrene shell type polymer microspheres were hierarchically changed from a disordered state to a face-centered cubic via a body-centered cubic. The transition of the lattice structures was investigated from the view point of the excluded volume of the microsphere, which was controlled by a changing of the molecular weights and blend tarios of polystyrene homopolymers.

  9. Multi-element spherical shell generation

    NASA Technical Reports Server (NTRS)

    Morrison, Andrew D. (Inventor)

    1990-01-01

    A nozzle assembly in a multi-element spherical shell generation system includes first and second side-by-side spaced apart nozzles and a web portion extending between and connecting the nozzles. The first nozzle has an inner orifice adapted to discharge a first filler material and an outer annular orifice separated from and defined in concentric relation about the inner orifice and adapted to discharge a first shell material. The second nozzle has an inner orifice adapted to discharge a second filler material and an outer annular orifice separated from and defined in concentric relation about the inner orifice and adapted to discharge a second shell material. A multi-element spherical shell can be formed through employment of the nozzle assembly by merger with one another after discharge from the outer orifices of the nozzles of a pair of adjacent annular streams of liquid or molten shell wall material of different compositions and encapsulation by the mixed shell wall materials of a common encapsulated core fluids also simultaneously discharged by the inner orifices nozzles. On the other hand, the pair of encapsulating streams of shell wall material can be of the same materials which merge together and encapsulate core fluids of different compositions which will merge together after discharge from the nozzles.

  10. Probabilistic Dynamic Buckling of Smart Composite Shells

    NASA Technical Reports Server (NTRS)

    Abumeri, Galib H.; Chamis, Christos C.

    2003-01-01

    A computational simulation method is presented to evaluate the deterministic and nondeterministic dynamic buckling of smart composite shells. The combined use of composite mechanics, finite element computer codes, and probabilistic analysis enable the effective assessment of the dynamic buckling load of smart composite shells. A universal plot is generated to estimate the dynamic buckling load of composite shells at various load rates and probabilities. The shell structure is also evaluated with smart fibers embedded in the plies right below the outer plies. The results show that, on the average, the use of smart fibers improved the shell buckling resistance by about 10 percent at different probabilities and delayed the buckling occurrence time. The probabilistic sensitivities results indicate that uncertainties in the fiber volume ratio and ply thickness have major effects on the buckling load while uncertainties in the electric field strength and smart material volume fraction have moderate effects. For the specific shell considered in this evaluation, the use of smart composite material is not recommended because the shell buckling resistance can be improved by simply re-arranging the orientation of the outer plies, as shown in the dynamic buckling analysis results presented in this report.

  11. Probabilistic Dynamic Buckling of Smart Composite Shells

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.; Abumeri, Galib H.

    2007-01-01

    A computational simulation method is presented to evaluate the deterministic and nondeterministic dynamic buckling of smart composite shells. The combined use of intraply hybrid composite mechanics, finite element computer codes, and probabilistic analysis enable the effective assessment of the dynamic buckling load of smart composite shells. A universal plot is generated to estimate the dynamic buckling load of composite shells at various load rates and probabilities. The shell structure is also evaluated with smart fibers embedded in the plies right next to the outer plies. The results show that, on the average, the use of smart fibers improved the shell buckling resistance by about 10% at different probabilities and delayed the buckling occurrence time. The probabilistic sensitivities results indicate that uncertainties in the fiber volume ratio and ply thickness have major effects on the buckling load while uncertainties in the electric field strength and smart material volume fraction have moderate effects. For the specific shell considered in this evaluation, the use of smart composite material is not recommended because the shell buckling resistance can be improved by simply re-arranging the orientation of the outer plies, as shown in the dynamic buckling analysis results presented in this report.

  12. Large ultrathin shelled drops produced via non-confined microfluidics.

    PubMed

    Chaurasia, Ankur S; Josephides, Dimitris N; Sajjadi, Shahriar

    2015-02-01

    We present a facile approach for producing large and monodisperse core-shell drops with ultrathin shells using a single-step process. A biphasic compound jet is introduced into a quiescent third (outer) phase that ruptures to form core-shell drops. Ultrathin shelled drops could only be produced within a certain range of surfactant concentrations and flow rates, highlighting the effect of interfacial tension in engulfing the core in a thin shell. An increase in surfactant concentrations initially resulted in drops with thinner shells. However, the drops with thinnest shells were obtained at an optimum surfactant concentration, and a further increase in the surfactant concentrations increased the shell thickness. Highly monodisperse (coefficient of variation smaller than 3 %) core-shell drops with diameter of ∼200 μm-2 mm with shell thickness as small as ∼2 μm were produced. The resulting drops were stable enough to undergo polymerisation and produce ultrathin shelled capsules.

  13. 1/12-Scale scoping experiments to characterize double-shell tank slurry uniformity: Test plan

    SciTech Connect

    Bamberger, J.A.; Liljegren, L.M.

    1994-10-01

    Million gallon double-shell tanks (DSTs) at Hanford are used to store transuranic, high-level, and low-level wastes. These wastes generally consist of a large volume of salt-laden solution covering a smaller volume of settled sludge primarily containing metal hydroxides. These wastes will be retrieved and processed into immobile waste forms suitable for permanent disposal. The current retrieval concept is to use submerged dual-nozzle pumps to mobilize the settled solids by creating jets of fluid that are directed at the tank solids. The pumps oscillate, creating arcs of high-velocity fluid jets that sweep the floor of the tank. After the solids are mobilized, the pumps will continue to operate at a reduced flow rate sufficient to maintain the particles in a uniform suspension. The objectives of these 1/12-scale scoping experiments are to determine how Reynolds number, Froude number, and gravitational settling parameter affect the degree of uniformity achieved during jet mixer pump operation in the full-scale double-shell tanks; develop linear models to predict the degree of uniformity achieved by jet mixer pumps operating in the full-scale double-shell tanks; apply linear models to predict the degree of uniformity that will be achieved in tank 241-AZ-101 and determine whether contents of that tank will be uniform to within {+-} 10% of the mean concentration; and obtain experimental concentration and jet velocity data to compared with the TEMPEST computational and modeling predictions to guide further code development.

  14. Synthesis of stiffened shells of revolution

    NASA Technical Reports Server (NTRS)

    Thornton, W. A.

    1974-01-01

    Computer programs for the synthesis of shells of various configurations were developed. The conditions considered are: (1) uniform shells (mainly cones) using a membrane buckling analysis, (2) completely uniform shells (cones, spheres, toroidal segments) using linear bending prebuckling analysis, and (3) revision of second design process to reduce the number of design variables to about 30 by considering piecewise uniform designs. A perturbation formula was derived and this allows exact derivatives of the general buckling load to be computed with little additional computer time.

  15. Laminated anisotropic reinforced plastic plates and shells

    NASA Technical Reports Server (NTRS)

    Korolev, V. I.

    1981-01-01

    Basic technical theories and engineering calculation equations for anisotropic plates and shells made of rigid reinforced plastics, mainly laminated fiberglass, are presented and discussed. Solutions are given for many problems of design of structural plates and shells, including curved sections and tanks, as well as two chapters on selection of the optimum materials, are given. Accounting for interlayer shearing and transverse separation, which are new engineering properties, are discussed. Application of the results obtained to thin three ply plates and shells wth a light elastic filler is presented and discussed.

  16. Magnetic-Plasmonic Core-Shell Nanoparticles

    PubMed Central

    Levin, Carly S.; Hofmann, Cristina; Ali, Tamer A.; Kelly, Anna T.; Morosan, Emilia; Nordlander, Peter; Whitmire, Kenton H.; Halas, Naomi J.

    2013-01-01

    Nanoparticles composed of magnetic cores with continuous Au shell layers simultaneously possess both magnetic and plasmonic properties. Faceted and tetracubic nanocrystals consisting of wüstite with magnetite-rich corners and edges retain magnetic properties when coated with an Au shell layer, with the composite nanostructures showing ferrimagnetic behavior. The plasmonic properties are profoundly influenced by the high dielectric constant of the mixed-iron-oxide nanocrystalline core. A comprehensive theoretical analysis that examines the geometric plasmon tunability over a range of core permittivities enables us to identify the dielectric properties of the mixed-oxide magnetic core directly from the plasmonic behavior of the core-shell nanoparticle. PMID:19441794

  17. Thin shells joining local cosmic string geometries

    NASA Astrophysics Data System (ADS)

    Eiroa, Ernesto F.; Rubín de Celis, Emilio; Simeone, Claudio

    2016-10-01

    In this article we present a theoretical construction of spacetimes with a thin shell that joins two different local cosmic string geometries. We study two types of global manifolds, one representing spacetimes with a thin shell surrounding a cosmic string or an empty region with Minkowski metric, and the other corresponding to wormholes which are not symmetric across the throat located at the shell. We analyze the stability of the static configurations under perturbations preserving the cylindrical symmetry. For both types of geometries we find that the static configurations can be stable for suitable values of the parameters.

  18. Gross shell structure of moments of inertia

    SciTech Connect

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

    2002-07-01

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

  19. Shell states of neutron-rich matter

    NASA Astrophysics Data System (ADS)

    Horowitz, C. J.; Shen, G.

    2008-07-01

    The equation of state (EOS) for nuclear and neutron rich matter is investigated in a relativistic mean field (RMF) model. New shell states are found that minimize the free energy per baryon, calculated in a spherical Wigner-Seitz (WS) approximation, over a significant range of baryon densities. These shell states, that have both inside and outside surfaces, minimize the Coulomb energy of large proton number configurations at the expense of a larger surface energy. This is related to a possible depression in the central density of super heavy nuclei. As the baryon density increases, we find the system changes from normal nuclei, to shell states, and then to uniform matter.

  20. Shell states of neutron-rich matter

    SciTech Connect

    Horowitz, C. J.; Shen, G.

    2008-07-15

    The equation of state (EOS) for nuclear and neutron rich matter is investigated in a relativistic mean field (RMF) model. New shell states are found that minimize the free energy per baryon, calculated in a spherical Wigner-Seitz (WS) approximation, over a significant range of baryon densities. These shell states, that have both inside and outside surfaces, minimize the Coulomb energy of large proton number configurations at the expense of a larger surface energy. This is related to a possible depression in the central density of super heavy nuclei. As the baryon density increases, we find the system changes from normal nuclei, to shell states, and then to uniform matter.

  1. Effective Interactions from No Core Shell Model

    SciTech Connect

    Dikmen, E.; Lisetskiy, A. F.; Barrett, B. R.; Navratil, P.; Vary, J. P.

    2008-11-11

    We construct the many-body effective Hamiltonian for pf-shell by carrying out 2({Dirac_h}/2{pi}){omega}. NCSM calculations at the 2-body cluster level. We demonstrate how the effective Hamiltonian derived from realistic nucleon-nucleon (NN) potentials for the 2({Dirac_h}/2{pi}){omega} NCSM space should be modified to properly account for the many-body correlations produced by truncating to the major pf-shell. We obtain two-body effective interactions for the pf-shell by using direct projection and use them to reproduce the results of large scale NCSM for other light Ca isotopes.

  2. THE PYTHON SHELL FOR THE ORBIT CODE

    SciTech Connect

    Shishlo, Andrei P; Gorlov, Timofey V; Holmes, Jeffrey A

    2009-01-01

    A development of a Python driver shell for the ORBIT simulation code is presented. The original ORBIT code uses the SuperCode shell to organize accelerator-related simulations. It is outdated, unsupported, and it is an obstacle to future code development. The necessity and consequences of replacing the old shell language are discussed. A set of core modules and extensions that are currently in PyORBIT are presented. They include particle containers, parsers for MAD and SAD lattice files, a Python wrapper for MPI libraries, space charge calculators, TEAPOT trackers, and a laser stripping extension module.

  3. Thermoluminescence analysis of irradiated oyster shells.

    PubMed

    Cruz-Zaragoza, E; Marcazzó, J; Della Monaca, S; Boniglia, C; Gargiulo, R; Bortolin, E

    2012-12-01

    This paper reports the thermoluminescence (TL) analysis performed on the oyster shells powder. TL response of (60)Co gamma-rays irradiated samples were studied in the range from 80 Gy to 8 kGy doses. TL signal of irradiated shell powder was higher as compared to the unirradiated control samples, which allowed to identify the irradiated oysters. Results show that the oyster shells have good TL properties and can be useful for the identification of irradiated seafood as well as for the evaluation of the treatment dose.

  4. Stress Recovery and Error Estimation for 3-D Shell Structures

    NASA Technical Reports Server (NTRS)

    Riggs, H. R.

    2000-01-01

    The C1-continuous stress fields obtained from finite element analyses are in general lower- order accurate than are the corresponding displacement fields. Much effort has focussed on increasing their accuracy and/or their continuity, both for improved stress prediction and especially error estimation. A previous project developed a penalized, discrete least squares variational procedure that increases the accuracy and continuity of the stress field. The variational problem is solved by a post-processing, 'finite-element-type' analysis to recover a smooth, more accurate, C1-continuous stress field given the 'raw' finite element stresses. This analysis has been named the SEA/PDLS. The recovered stress field can be used in a posteriori error estimators, such as the Zienkiewicz-Zhu error estimator or equilibrium error estimators. The procedure was well-developed for the two-dimensional (plane) case involving low-order finite elements. It has been demonstrated that, if optimal finite element stresses are used for the post-processing, the recovered stress field is globally superconvergent. Extension of this work to three dimensional solids is straightforward. Attachment: Stress recovery and error estimation for shell structure (abstract only). A 4-node, shear-deformable flat shell element developed via explicit Kirchhoff constraints (abstract only). A novel four-node quadrilateral smoothing element for stress enhancement and error estimation (abstract only).

  5. Supramolecular core-shell nanoparticles for photoconductive device applications

    NASA Astrophysics Data System (ADS)

    Cheng, Chih-Chia; Chen, Jem-Kun; Shieh, Yeong-Tarng; Lee, Duu-Jong

    2016-08-01

    We report a breakthrough discovery involving supramolecular-based strategies to construct novel core-shell heterojunction nanoparticles with hydrophilic adenine-functionalized polythiophene (PAT) as the core and hydrophobic phenyl-C61-butyric acid methyl ester (PCBM) as the shell, which enables the conception of new functional supramolecular assemblies for constructing functional nanomaterials for applications in optoelectronic devices. The generated nanoparticles exhibit uniform spherical shape, well-controlled tuning of particle size with narrow size distributions, and excellent electrochemical stability in solution and the solid state owing to highly efficient energy transfer from PAT to PCBM. When the PAT/PCBM nanoparticles were fabricated into a photoconducting layer in an electronic device, the resulting device showed excellent electric conduction characteristics, including an electrically-tunable voltage-controlled switch, and high short-circuit current and open-circuit voltage. These observations demonstrate how the self-assembly of PAT/PCBM into specific nanostructures may help to promote efficient charge generation and transport processes, suggesting potential for a wide variety of applications as a promising candidate material for bulk heterojunction polymer devices.

  6. Supramolecular core–shell nanoparticles for photoconductive device applications

    NASA Astrophysics Data System (ADS)

    Cheng, Chih-Chia; Chen, Jem-Kun; Shieh, Yeong-Tarng; Lee, Duu-Jong

    2016-08-01

    We report a breakthrough discovery involving supramolecular-based strategies to construct novel core–shell heterojunction nanoparticles with hydrophilic adenine-functionalized polythiophene (PAT) as the core and hydrophobic phenyl-C61-butyric acid methyl ester (PCBM) as the shell, which enables the conception of new functional supramolecular assemblies for constructing functional nanomaterials for applications in optoelectronic devices. The generated nanoparticles exhibit uniform spherical shape, well-controlled tuning of particle size with narrow size distributions, and excellent electrochemical stability in solution and the solid state owing to highly efficient energy transfer from PAT to PCBM. When the PAT/PCBM nanoparticles were fabricated into a photoconducting layer in an electronic device, the resulting device showed excellent electric conduction characteristics, including an electrically-tunable voltage-controlled switch, and high short-circuit current and open-circuit voltage. These observations demonstrate how the self-assembly of PAT/PCBM into specific nanostructures may help to promote efficient charge generation and transport processes, suggesting potential for a wide variety of applications as a promising candidate material for bulk heterojunction polymer devices.

  7. Supramolecular core-shell nanoparticles for photoconductive device applications.

    PubMed

    Cheng, Chih-Chia; Chen, Jem-Kun; Shieh, Yeong-Tarng; Lee, Duu-Jong

    2016-08-12

    We report a breakthrough discovery involving supramolecular-based strategies to construct novel core-shell heterojunction nanoparticles with hydrophilic adenine-functionalized polythiophene (PAT) as the core and hydrophobic phenyl-C61-butyric acid methyl ester (PCBM) as the shell, which enables the conception of new functional supramolecular assemblies for constructing functional nanomaterials for applications in optoelectronic devices. The generated nanoparticles exhibit uniform spherical shape, well-controlled tuning of particle size with narrow size distributions, and excellent electrochemical stability in solution and the solid state owing to highly efficient energy transfer from PAT to PCBM. When the PAT/PCBM nanoparticles were fabricated into a photoconducting layer in an electronic device, the resulting device showed excellent electric conduction characteristics, including an electrically-tunable voltage-controlled switch, and high short-circuit current and open-circuit voltage. These observations demonstrate how the self-assembly of PAT/PCBM into specific nanostructures may help to promote efficient charge generation and transport processes, suggesting potential for a wide variety of applications as a promising candidate material for bulk heterojunction polymer devices. PMID:27353003

  8. Deformation and failure of curved colloidal crystal shells

    PubMed Central

    Negri, Carlotta; Sellerio, Alessandro L.; Zapperi, Stefano

    2015-01-01

    Designing and controlling particle self-assembly into robust and reliable high-performance smart materials often involves crystalline ordering in curved spaces. Examples include carbon allotropes like graphene, synthetic materials such as colloidosomes, or biological systems like lipid membranes, solid domains on vesicles, or viral capsids. Despite the relevance of these structures, the irreversible deformation and failure of curved crystals is still mostly unexplored. Here, we report simulation results of the mechanical deformation of colloidal crystalline shells that illustrate the subtle role played by geometrically necessary topological defects in controlling plastic yielding and failure. We observe plastic deformation attributable to the migration and reorientation of grain boundary scars, a collective process assisted by the intermittent proliferation of disclination pairs or abrupt structural failure induced by crack nucleating at defects. Our results provide general guiding principles to optimize the structural and mechanical stability of curved colloidal crystals. PMID:26553975

  9. Colloidal Quantum Dot Photovoltaics Enhanced by Perovskite Shelling.

    PubMed

    Yang, Zhenyu; Janmohamed, Alyf; Lan, Xinzheng; García de Arquer, F Pelayo; Voznyy, Oleksandr; Yassitepe, Emre; Kim, Gi-Hwan; Ning, Zhijun; Gong, Xiwen; Comin, Riccardo; Sargent, Edward H

    2015-11-11

    Solution-processed quantum dots are a promising material for large-scale, low-cost solar cell applications. New device architectures and improved passivation have been instrumental in increasing the performance of quantum dot photovoltaic devices. Here we report photovoltaic devices based on inks of quantum dot on which we grow thin perovskite shells in solid-state films. Passivation using the perovskite was achieved using a facile solution ligand exchange followed by postannealing. The resulting hybrid nanostructure created a more intrinsic CQD film, which, when incorporated into a photovoltaic device with graded bandstructure, achieved a record solar cell performance for single-step-deposited CQD films, exhibiting an AM1.5 solar power conversion efficiency of 8.95%.

  10. Deformation and failure of curved colloidal crystal shells.

    PubMed

    Negri, Carlotta; Sellerio, Alessandro L; Zapperi, Stefano; Miguel, M Carmen

    2015-11-24

    Designing and controlling particle self-assembly into robust and reliable high-performance smart materials often involves crystalline ordering in curved spaces. Examples include carbon allotropes like graphene, synthetic materials such as colloidosomes, or biological systems like lipid membranes, solid domains on vesicles, or viral capsids. Despite the relevance of these structures, the irreversible deformation and failure of curved crystals is still mostly unexplored. Here, we report simulation results of the mechanical deformation of colloidal crystalline shells that illustrate the subtle role played by geometrically necessary topological defects in controlling plastic yielding and failure. We observe plastic deformation attributable to the migration and reorientation of grain boundary scars, a collective process assisted by the intermittent proliferation of disclination pairs or abrupt structural failure induced by crack nucleating at defects. Our results provide general guiding principles to optimize the structural and mechanical stability of curved colloidal crystals. PMID:26553975

  11. Sensitivity and Uncertainty Analysis Shell

    1999-04-20

    SUNS (Sensitivity and Uncertainty Analysis Shell) is a 32-bit application that runs under Windows 95/98 and Windows NT. It is designed to aid in statistical analyses for a broad range of applications. The class of problems for which SUNS is suitable is generally defined by two requirements: 1. A computer code is developed or acquired that models some processes for which input is uncertain and the user is interested in statistical analysis of the outputmore » of that code. 2. The statistical analysis of interest can be accomplished using the Monte Carlo analysis. The implementation then requires that the user identify which input to the process model is to be manipulated for statistical analysis. With this information, the changes required to loosely couple SUNS with the process model can be completed. SUNS is then used to generate the required statistical sample and the user-supplied process model analyses the sample. The SUNS post processor displays statistical results from any existing file that contains sampled input and output values.« less

  12. Membrane Shell Reflector Segment Antenna

    NASA Technical Reports Server (NTRS)

    Fang, Houfei; Im, Eastwood; Lin, John; Moore, James

    2012-01-01

    The mesh reflector is the only type of large, in-space deployable antenna that has successfully flown in space. However, state-of-the-art large deployable mesh antenna systems are RF-frequency-limited by both global shape accuracy and local surface quality. The limitations of mesh reflectors stem from two factors. First, at higher frequencies, the porosity and surface roughness of the mesh results in loss and scattering of the signal. Second, the mesh material does not have any bending stiffness and thus cannot be formed into true parabolic (or other desired) shapes. To advance the deployable reflector technology at high RF frequencies from the current state-of-the-art, significant improvements need to be made in three major aspects: a high-stability and highprecision deployable truss; a continuously curved RF reflecting surface (the function of the surface as well as its first derivative are both continuous); and the RF reflecting surface should be made of a continuous material. To meet these three requirements, the Membrane Shell Reflector Segment (MSRS) antenna was developed.

  13. Acetabular shell deformation as a function of shell stiffness and bone strength.

    PubMed

    Dold, Philipp; Pandorf, Thomas; Flohr, Markus; Preuss, Roman; Bone, Martin C; Joyce, Tom J; Holland, James; Deehan, David

    2016-04-01

    Press-fit acetabular shells used for hip replacement rely upon an interference fit with the bone to provide initial stability. This process may result in deformation of the shell. This study aimed to model shell deformation as a process of shell stiffness and bone strength. A cohort of 32 shells with two different wall thicknesses (3 and 4 mm) and 10 different shell sizes (44- to 62-mm outer diameter) were implanted into eight cadavers. Shell deformation was then measured in the cadavers using a previously validated ATOS Triple Scan III optical system. The shell-bone interface was then considered as a spring system according to Hooke's law and from this the force exerted on the shell by the bone was calculated using a combined stiffness consisting of the measured shell stiffness and a calculated bone stiffness. The median radial stiffness for the 3-mm wall thickness was 4192 N/mm (range, 2920-6257 N/mm), while for the 4-mm wall thickness the median was 9633 N/mm (range, 6875-14,341 N/mm). The median deformation was 48 µm (range, 3-187 µm), while the median force was 256 N (range, 26-916 N). No statistically significant correlation was found between shell stiffness and deformation. Deformation was also found to be not fully symmetric (centres 180° apart), with a median angle discrepancy of 11.5° between the two maximum positive points of deformation. Further work is still required to understand how the bone influences acetabular shell deformation.

  14. Shell-Model Calculations of f p-shell Nuclei with Realistic NN Interactions

    SciTech Connect

    Qi, C.; Xu, F. R.

    2010-05-12

    Shell model calculations have been carried out to study the structure and decay properties of nuclei in the f p shell. The shell-model effective Hamiltonian is constructed from the high-precision CD-Bonn NN potential using the folded-diagram renormalization method without any empirical modification. The Hamiltonian gives a reasonable description of spectroscopic properties in nuclei around the N = Z line.

  15. Wireless energy transfer between anisotropic metamaterials shells

    SciTech Connect

    Díaz-Rubio, Ana; Carbonell, Jorge; Sánchez-Dehesa, José

    2014-06-15

    The behavior of strongly coupled Radial Photonic Crystals shells is investigated as a potential alternative to transfer electromagnetic energy wirelessly. These sub-wavelength resonant microstructures, which are based on anisotropic metamaterials, can produce efficient coupling phenomena due to their high quality factor. A configuration of selected constitutive parameters (permittivity and permeability) is analyzed in terms of its resonant characteristics. The coupling to loss ratio between two coupled resonators is calculated as a function of distance, the maximum (in excess of 300) is obtained when the shells are separated by three times their radius. Under practical conditions an 83% of maximum power transfer has been also estimated. -- Highlights: •Anisotropic metamaterial shells exhibit high quality factors and sub-wavelength size. •Exchange of electromagnetic energy between shells with high efficiency is analyzed. •Strong coupling is supported with high wireless transfer efficiency. •End-to-end energy transfer efficiencies higher than 83% can be predicted.

  16. On the Calculation of Shallow Shells

    NASA Technical Reports Server (NTRS)

    Ambartsumyan, S. A.

    1956-01-01

    This paper considers a sufficiently thin shallow shell of nonzero Gaussian curvature. It also presents a system of symmetrically constructed differential equations, constructed by the mixed method through the stress function and the displpacement function.

  17. A new view of nuclear shells

    NASA Astrophysics Data System (ADS)

    Kanungo, Rituparna

    2013-01-01

    The nuclear shell structure that has served as a fundamental framework for understanding the arrangement of nucleons exhibits dramatic changes as the neutron to proton ratio in nuclei increases. This paper describes how reaction spectroscopy of the neutron- and proton-rich nuclei has brought about a new revolution towards a more global view of nuclear shells. The relationship between changes in shell structure and the discovery of exotic forms of nuclei such as nuclear halo and skin is discussed. It is shown that the well-known shell gaps (magic numbers) N = 8 and 20 disappear. The discovery of a new magic number at N = 16 at the limit of nuclear binding is discussed.

  18. Nuclear Quadrupole Moments and Nuclear Shell Structure

    DOE R&D Accomplishments Database

    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.

  19. Shell nuclear explosions in degenerate dwarfs

    NASA Astrophysics Data System (ADS)

    Kuznetsov, O. A.; Tutukov, A. V.; Chechetkin, V. M.

    1989-08-01

    Numerical gas dynamics simulations are used to study shell nuclear explosions of degenerate carbon-oxygen dwarfs with masses of 1.17, 1.36, and 1.42 solar masses. It is assumed that the calorific capacity of the burning shell matter is between 5 X 10 to the 17th and 5 X 10 to the 18th erg/g. It is shown that, at a low calorific capacity, a remnant may form if the mass of the shell is less than 90 percent of the mass of the degenerate dwarf. In the case of high calorific capacity, a remnant may form only if the mass of the shell is less than half of the dwarf's mass.

  20. Design of efficient stiffened shells of revolution

    NASA Technical Reports Server (NTRS)

    Majumder, D. K.; Thornton, W. A.

    1976-01-01

    A method to produce efficient piecewise uniform stiffened shells of revolution is presented. The approach uses a first order differential equation formulation for the shell prebuckling and buckling analyses and the necessary conditions for an optimum design are derived by a variational approach. A variety of local yielding and buckling constraints and the general buckling constraint are included in the design process. The local constraints are treated by means of an interior penalty function and the general buckling load is treated by means of an exterior penalty function. This allows the general buckling constraint to be included in the design process only when it is violated. The self-adjoint nature of the prebuckling and buckling formulations is used to reduce the computational effort. Results for four conical shells and one spherical shell are given.

  1. Shell Eggs from Farm to Table

    MedlinePlus

    ... and stored and transported under refrigeration and ambient temperature of no greater than 45 °F. USDA also ... transported under refrigeration at an ambient (surrounding) air temperature not to exceed 45 °F; All packed shell ...

  2. Damping control of 'smart' piezoelectric shell structures

    NASA Astrophysics Data System (ADS)

    Tzou, H. S.

    Advanced 'smart' structures with self-sensation and control capabilities have attracted much attention in recent years. 'Smart' piezoelectric structures (conventional structures integrated with piezoelectric sensor and actuator elements) possessing self-monitoring and adaptive static and/or dynamic characteristics are very promising in many applications. This paper presents a study on 'smart' piezoelectric shell structures. A generic piezoelastic vibration theory for a thin piezoelectric shell continuum made of a hexagonal piezoelectric material is first derived. Piezoelastic system equation and electrostatic charge equation are formulated using Hamilton's principle and Kirchhoff-Love thin shell assumptions. Dynamic adaptivity, damping control, of a simply supported cylindrical shell structure is demonstrated in a case study. It shows that the system damping increases with the increase of feedback voltage for odd modes. The control scheme is ineffective for all even modes because of the symmetrical boundary conditions.

  3. 41 CFR 102-85.120 - What is shell Rent?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false What is shell Rent? 102... GSA SPACE Rent Charges § 102-85.120 What is shell Rent? Shell Rent is that portion of GSA Rent charged for the building envelope and land. (See § 102-85.35 for the definition of building shell.)...

  4. Silica shell/gold core nanoparticles: correlating shell thickness with the plasmonic red shift upon aggregation.

    PubMed

    Vanderkooy, Alan; Chen, Yang; Gonzaga, Ferdinand; Brook, Michael A

    2011-10-01

    Differences in the wavelengths of the surface plasmon band of gold nanoparticles (AuNP)--before and after particle aggregation--are widely used in bioanalytical assays. However, the gold surfaces in such bioassays can suffer from exchange and desorption of noncovalently bound ligands and from nonspecific adsorption of biomolecules. Silica shells on the surfaces of the gold can extend the available surface chemistries for bioconjugation and potentially avoid these issues. Therefore, silica was grown on gold surfaces using either hydrolysis/condensation of tetraethyl orthosilicate 1 under basic conditions or diglyceroxysilane 2 at neutral pH. The former precursor permitted slow, controlled growth of shells from about 1.7 to 4.3 nm thickness. By contrast, 3-4 nm thick silica shells formed within an hour using diglyceroxysilane; thinner or thicker shells were not readily available. Within the range of shell thicknesses synthesized, the presence of a silica shell on the gold nanoparticle did not significantly affect the absorbance maximum (~5 nm) of unaggregated particles. However, the change in absorbance wavelength upon aggregation of the particles was highly dependent on the thickness of the shell. With silica shells coating the AuNP, there was a significant decrease in the absorbance maximum of the aggregated particles, from ~578 to ~536 nm, as the shell thicknesses increased from ~1.7 to ~4.3 nm, because of increased distance between adjacent gold cores. These studies provide guidance for the development of colorimetric assays using silica-coated AuNP.

  5. Experimental study of upper sd shell nuclei and evolution of sd-fp shell gap

    SciTech Connect

    Sarkar, M. Saha

    2012-06-27

    The intruder orbitals from the fp shell play important role in the structure of nuclei around the line of stability in the upper sd shell. Experimentally we have studied {sup 35}Cl, {sup 30}P, {sup 36}Cl, {sup 37}Ar and {sup 34}Cl in this mass region using the INGA setup. Large basis cross-shell shell model calculations have indicated the need for change of the sd-fp energy gap for reliable reproduction of negative parity and high spin positive parity states. Indication of population of states of large deformation has been found in our data. Theoretical interpretation of these states has been discussed.

  6. Shell-model study for neutron-rich sd-shell nuclei

    SciTech Connect

    Kaneko, Kazunari; Sun Yang; Mizusaki, Takahiro; Hasegawa, Munetake

    2011-01-15

    The microscopic structure of neutron-rich sd-shell nuclei is investigated by using the spherical-shell model in the sd-pf valence space with the extended pairing plus quadrupole-quadrupole forces accompanied by the monopole interaction (EPQQM). The calculation reproduces systematically the known energy levels for even-even and odd-mass nuclei including the recent data for {sup 43}S, {sup 46}S, and {sup 47}Ar. In particular, the erosion of the N=28 shell closure in {sup 42}Si can be explained. Our EPQQM results are compared with other shell-model calculations with the SDPF-NR and SDPF-U effective interactions.

  7. Structural durability of stiffened composite shells

    NASA Technical Reports Server (NTRS)

    Minnetyan, Levon; Rivers, James M.; Murthy, Pappu L. N.; Chamis, Christos C.

    1992-01-01

    The durability of a stiffened composite cylindrical shell panel is investigated under several loading conditions. An integrated computer code is utilized for the simulation of load induced structural degradation. Damage initiation, growth, and accumulation up to the stage of propagation to fracture are included in the computational simulation. Results indicate significant differences in the degradation paths for different loading cases. The effects of combined loading on structural durability and ultimate structural strength of a stiffened shell are assessed.

  8. Double shell tank waste analysis plan

    SciTech Connect

    Mulkey, C.H.; Jones, J.M.

    1994-12-15

    Waste analysis plan for the double shell tanks. SD-WM-EV-053 is Superseding SD-WM-EV-057.This document provides the plan for obtaining information needed for the safe waste handling and storage of waste in the Double Shell Tank Systems. In Particular it addresses analysis necessary to manage waste according to Washington Administrative Code 173-303 and Title 40, parts 264 and 265 of the Code of Federal Regulations.

  9. Kramers' Restricted Closed Shell CCSD Theory

    NASA Technical Reports Server (NTRS)

    Visscher, Lucas; Dyall, Kenneth G.; Lee, Timothy J.; Langhoff, Stephen R. (Technical Monitor)

    1995-01-01

    A Kramers' restricted version of the closed shell coupled cluster singles doubles theory is presented. The theory may be used in conjunction with 2 or 4-component relativistic reference wavefunctions. The intrinsic treatment of the spin-orbit coupling doubles the number of independent quantities (amplitudes and integrals) relative to a spin-independent formalism. The number of operations required to evaluate the equations is four times larger than in the optimal spin-independent closed shell formalism.

  10. Trapping of intense light in hollow shell

    SciTech Connect

    Luan, Shixia; Yu, Wei; Yu, M. Y.; Weng, Suming; Wang, Jingwei; Xu, Han; Zhuo, Hongbin; Wong, A. Y.

    2015-09-15

    A small hollow shell for trapping laser light is proposed. Two-dimensional particle-in-cell simulation shows that under appropriate laser and plasma conditions a part of the radiation fields of an intense short laser pulse can enter the cavity of a small shell through an over-critical density plasma in an adjacent guide channel and become trapped. The trapped light evolves into a circulating radial wave pattern until its energy is dissipated.

  11. The Strength of Shell and Tubular Spar Wings

    NASA Technical Reports Server (NTRS)

    Ebner, H

    1940-01-01

    The report is a survey of the strength problems arising on shell and tubular spar wings. The treatment of the shell wing strength is primarily confined to those questions which concern the shell wing only; those pertaining to both shell wing and shell body together have already been treated in TM 838. The discussion of stress condition and compressive strength of shell wings and tubular spar wings is prefaced by several considerations concerning the spar and shell design of metal wings from the point of view of strength.

  12. New developments of the nuclear shell model

    NASA Astrophysics Data System (ADS)

    Poves, Alfredo

    2002-04-01

    More than fifty years ago, the independent particle model of the nucleus was proposed by M. Goeppert-Mayer and H. Jensen. The label "shell model" has since changed meaning and nowadays it applies mainly to the description of the nucleus that results of the mixing of many Slater determinants by an effective "in medium" interaction, usually limited to one and two-body terms. The advent of efficient new algorithms to solve the secular problem, together with the increase in speed and storage capacity of modern computers, has brought into the reach of large scale shell model calculations entire regions of nuclei and of nuclear phenomena traditionally considered to be out of the shell model realm. This enormous extension of its field of practical applications has occurred simultaneously with a regain of experimental interest in the nuclear spectroscopy, in particular in very neutron rich and N=Z nuclei. The shell model work in large model spaces demands a very complete understanding of the effective nuclear interaction, a basic goal of the nuclear theory. Besides, the huge increase of dimensionality that occurs when many valence orbits and valence particles are involved, is a formidable challenge for both the direct diagonalization shell model codes and for the many different approximations, based most often in physically guided truncations of the full shell model basis. In this talk I aim to transmit the effervescence of the field by highlighting the most important recent advances and applications.

  13. Experiments on shells under base excitation

    NASA Astrophysics Data System (ADS)

    Pellicano, Francesco; Barbieri, Marco; Zippo, Antonio; Strozzi, Matteo

    2016-05-01

    The aim of the present paper is a deep experimental investigation of the nonlinear dynamics of circular cylindrical shells. The specific problem regards the response of circular cylindrical shells subjected to base excitation. The shells are mounted on a shaking table that furnishes a vertical vibration parallel to the cylinder axis; a heavy rigid disk is mounted on the top of the shells. The base vibration induces a rigid body motion, which mainly causes huge inertia forces exerted by the top disk to the shell. In-plane stresses due to the aforementioned inertias give rise to impressively large vibration on the shell. An extremely violent dynamic phenomenon suddenly appears as the excitation frequency varies up and down close to the linear resonant frequency of the first axisymmetric mode. The dynamics are deeply investigated by varying excitation level and frequency. Moreover, in order to generalise the investigation, two different geometries are analysed. The paper furnishes a complete dynamic scenario by means of: (i) amplitude frequency diagrams, (ii) bifurcation diagrams, (iii) time histories and spectra, (iv) phase portraits and Poincaré maps. It is to be stressed that all the results presented here are experimental.

  14. Batdorf parameter for the spherical shells tectonics

    NASA Astrophysics Data System (ADS)

    Kikuchi, Kazuhei; Nagahama, Hiroyuki

    2015-04-01

    The buckling phenomena of the subducting lithosphere due to the sphericity of the earth has been studied as spherical shell tectonics which happen the megaquake along the boundary of subducting lithosphere. The earthquake scale is decided by slab length or arc length. However, a relationship between slab length and the normalized hydrostatic pressure along the bottom circumferential edge of a hemispherical shell has not been clear yet. So, by using the data set of the geometrical parameters for subducting lithosphere andBuckingham's Pi-theorem, we found out a new linear relationship between Batdorf parameter Z = L2(l - v2)0.5/(Rh) for the measurement of the slab length L and the normalized hydrostatic pressure along the bottom circumferential edge of a hemispherical shell Q = qRL2/(π2D), where D = Eh3/[12(1 - v2)] with E = modulus of elasticity of lithosphere, R is Earth radius, q is the hydrostatic pressure along the bottom circumferential edge of a hemispherical shell, and h is the thickness of subducting lithosphere. In the engineering sciences, a similar relationship between Batdorf parameter for the panel length and normalized hydrostatic pressure was proposed for the buckling of partially liquid-filled circular cylindrical shells under hydrostatic pressure. Moreover, by previous researches, the slab length is approximately proportional to the arc length or the lithosphere thickness related to lithosphere age. Therefore, the Batdorf parameter for subducting lithosphere is an important parameter for the spherical shells tectonics.

  15. Distributed neural signals on parabolic cylindrical shells

    NASA Astrophysics Data System (ADS)

    Hu, S. D.; Li, H.; Tzou, H. S.

    2013-06-01

    Parabolic cylindrical shells are commonly used as key components in communication antennas, space telescopes, solar collectors, etc. This study focuses on distributed modal neural sensing signals on a flexible simply-supported parabolic cylindrical shell panel. The parabolic cylindrical shell is fully laminated with a piezoelectric layer on its outer surface and the piezoelectric layer is segmented into infinitesimal elements (neurons) to investigate the microscopic distributed neural sensing signals. Since the dominant vibration component of the shell is usually the transverse oscillation, a new transverse mode shape function is defined. Two shell cases, i.e., the ratio of the meridian height to the half span distance of a parabola at 1:4 (shallow) and 1:1 (deep), are studied to reveal the curvature effect to the neural sensing signals. Studies suggest that the membrane signal component dominates for lower natural modes and the bending signal component dominates for higher natural modes. The meridional membrane and bending signal components are mostly concentrated on the high-curvature areas, while the longitudinal bending component is mostly concentrated on the relatively flat areas. The concentration behavior becomes more prominent as the parabolic cylindrical shell deepens, primarily resulting from the enhanced membrane effect due to the increased curvature.

  16. Creation of optically-thin solid-density plasmas using LCLS

    NASA Astrophysics Data System (ADS)

    Preston, T.; Vinko, S. M.; Ciricosta, O.; Hollebon, P.; Wark, J. S.; Burian, T.; Chalupsky, J.; Vozda, V.; Minitti, M.; Dakovski, G.; Hall, F.; Spindloe, C.; Zastrau, U.

    2015-11-01

    The advent of X-ray free-electron-lasers such as LCLS provides the capability to truly isochorically heat solid-density matter on femtosecond time-scales. K-shell emission from such plasmas has provided new information on ionization potential depression and collisional ionisation rates. However, in previous work the targets were 1- μm thick, resulting in high-opacity on the K-shell transitions. We report here results of a detailed study of K-shell emission from exactly solid-density Mg plasmas with thicknesses ranging from 500 down to 25 nm - just over 100 atoms across. A curve-of-growth analysis exhibits text-book behavior, and confirms peak optical depths for the thinnest targets well below unity, in excellent agreement with simulations. The rich data-set provides information on line-widths, collisional dynamics, and radiation transfer in solid density plasmas.

  17. 50 CFR 648.50 - Shell-height standard.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 8 2010-10-01 2010-10-01 false Shell-height standard. 648.50 Section 648... Atlantic Sea Scallop Fishery § 648.50 Shell-height standard. (a) Minimum shell height. The minimum shell height for in-shell scallops that may be landed, or possessed at or after landing, is 3.5 inches (8.9...

  18. Nanorod and nanoparticle shells in concentration gradient core-shell lithium oxides for rechargeable lithium batteries.

    PubMed

    Yoon, Sung-June; Myung, Seung-Taek; Noh, Hyung-Joo; Lu, Jun; Amine, Khalil; Sun, Yang-Kook

    2014-12-01

    The structure, electrochemistry, and thermal stability of concentration gradient core-shell (CGCS) particles with different shell morphologies were evaluated and compared. We modified the shell morphology from nanoparticles to nanorods, because nanorods can result in a reduced surface area of the shell such that the outer shell would have less contact with the corrosive electrolyte, resulting in improved electrochemical properties. Electron microscopy studies coupled with electron probe X-ray micro-analysis revealed the presence of a concentration gradient shell consisting of nanoparticles and nanorods before and after thermal lithiation at high temperature. Rietveld refinement of the X-ray diffraction data and the chemical analysis results showed no variations of the lattice parameters and chemical compositions of both produced CGCS particles except for the degree of cation mixing (or exchange) in Li and transition metal layers. As anticipated, the dense nanorods present in the shell gave rise to a high tap density (2.5 g cm(-3) ) with a reduced pore volume and surface area. Intimate contact among the nanorods is likely to improve the resulting electric conductivity. As a result, the CGCS Li[Ni0.60 Co0.15 Mn0.25 ]O2 with the nanorod shell retained approximately 85.5% of its initial capacity over 150 cycles in the range of 2.7-4.5 V at 60 °C. The charged electrode consisting of Li0.16 [Ni0.60 Co0.15 Mn0.25 ]O2 CGCS particles with the nanorod shell also displayed a main exothermic reaction at 279.4 °C releasing 751.7 J g(-1) of heat. Due to the presence of the nanorod shell in the CGCS particles, the electrochemical and thermal properties are substantially superior to those of the CGCS particles with the nanoparticle shell.

  19. Nanorod and nanoparticle shells in concentration gradient core-shell lithium oxides for rechargeable lithium batteries.

    PubMed

    Yoon, Sung-June; Myung, Seung-Taek; Noh, Hyung-Joo; Lu, Jun; Amine, Khalil; Sun, Yang-Kook

    2014-12-01

    The structure, electrochemistry, and thermal stability of concentration gradient core-shell (CGCS) particles with different shell morphologies were evaluated and compared. We modified the shell morphology from nanoparticles to nanorods, because nanorods can result in a reduced surface area of the shell such that the outer shell would have less contact with the corrosive electrolyte, resulting in improved electrochemical properties. Electron microscopy studies coupled with electron probe X-ray micro-analysis revealed the presence of a concentration gradient shell consisting of nanoparticles and nanorods before and after thermal lithiation at high temperature. Rietveld refinement of the X-ray diffraction data and the chemical analysis results showed no variations of the lattice parameters and chemical compositions of both produced CGCS particles except for the degree of cation mixing (or exchange) in Li and transition metal layers. As anticipated, the dense nanorods present in the shell gave rise to a high tap density (2.5 g cm(-3) ) with a reduced pore volume and surface area. Intimate contact among the nanorods is likely to improve the resulting electric conductivity. As a result, the CGCS Li[Ni0.60 Co0.15 Mn0.25 ]O2 with the nanorod shell retained approximately 85.5% of its initial capacity over 150 cycles in the range of 2.7-4.5 V at 60 °C. The charged electrode consisting of Li0.16 [Ni0.60 Co0.15 Mn0.25 ]O2 CGCS particles with the nanorod shell also displayed a main exothermic reaction at 279.4 °C releasing 751.7 J g(-1) of heat. Due to the presence of the nanorod shell in the CGCS particles, the electrochemical and thermal properties are substantially superior to those of the CGCS particles with the nanoparticle shell. PMID:25044175

  20. Fabrication of poly(glycerol sebacate) fibrous membranes by coaxial electrospinning: Influence of shell and core solutions.

    PubMed

    You, Zhi-Rong; Hu, Ming-Hsien; Tuan-Mu, Ho-Yi; Hu, Jin-Jia

    2016-10-01

    Although poly(glycerol sebacate) (PGS) has enjoyed great success in soft tissue engineering, it remains challenging to fabricate PGS fibers. In this study, coaxial electrospinning, in which polylactide (PLA) was used to confine and draw PGS prepolymer, was used to fabricate PGS fibrous membranes. Specifically, effects of adding poly(ethylene oxide) (PEO), which was removed prior to curing, in the shell were investigated. Transmission and scanning electron microscopy were used to confirm core-shell structure and morphology of fibers, respectively. Both the removal of PEO or PLA in the shell and the efficacy of PGS curing were verified by Fourier transform infrared spectroscopy and differential scanning calorimetry. Mechanical properties of the membranes with different shell and core contents were examined. We found that the addition of PEO to the shell reduced Young׳s modulus of the resulting cured membrane and increased its elongation at break significantly, the latter indicating better PGS curing. Moreover, with the addition of PEO, increasing PGS prepolymer concentration further increased the elongation at break and appeared to enhance the structural integrity of fibers; PGS fibrous membranes (with no PLA shell) were thus successfully fabricated after the removal of PLA. The Young׳s modulus of the PGS fibrous membrane was ~0.47MPa, which is similar to that of PGS solid sheets and some soft tissues. Finally, the cytocompatibility of the electrospun membranes was validated by Alamar blue and LDH assays. PMID:27429071

  1. Fabrication of poly(glycerol sebacate) fibrous membranes by coaxial electrospinning: Influence of shell and core solutions.

    PubMed

    You, Zhi-Rong; Hu, Ming-Hsien; Tuan-Mu, Ho-Yi; Hu, Jin-Jia

    2016-10-01

    Although poly(glycerol sebacate) (PGS) has enjoyed great success in soft tissue engineering, it remains challenging to fabricate PGS fibers. In this study, coaxial electrospinning, in which polylactide (PLA) was used to confine and draw PGS prepolymer, was used to fabricate PGS fibrous membranes. Specifically, effects of adding poly(ethylene oxide) (PEO), which was removed prior to curing, in the shell were investigated. Transmission and scanning electron microscopy were used to confirm core-shell structure and morphology of fibers, respectively. Both the removal of PEO or PLA in the shell and the efficacy of PGS curing were verified by Fourier transform infrared spectroscopy and differential scanning calorimetry. Mechanical properties of the membranes with different shell and core contents were examined. We found that the addition of PEO to the shell reduced Young׳s modulus of the resulting cured membrane and increased its elongation at break significantly, the latter indicating better PGS curing. Moreover, with the addition of PEO, increasing PGS prepolymer concentration further increased the elongation at break and appeared to enhance the structural integrity of fibers; PGS fibrous membranes (with no PLA shell) were thus successfully fabricated after the removal of PLA. The Young׳s modulus of the PGS fibrous membrane was ~0.47MPa, which is similar to that of PGS solid sheets and some soft tissues. Finally, the cytocompatibility of the electrospun membranes was validated by Alamar blue and LDH assays.

  2. Synthesis of Co/MFe{sub 2}O{sub 4} (M=Fe, Mn) core/shell nanocomposite particles

    SciTech Connect

    Peng Sheng; Xie Jin; Sun Shouheng

    2008-07-15

    Monodispersed cobalt nanoparticles (NPs) with controllable size (8-14 nm) have been synthesized using thermal decomposition of dicobaltoctacarbonyl in organic solvent. The as-synthesized high magnetic moment (125 emu/g) Co NPs are dispersible in various organic solvents, and can be easily transferred into aqueous phase by surface modification using phospholipids. However, the modified hydrophilic Co NPs are not stable as they are quickly oxidized, agglomerated in buffer. Co NPs are stabilized by coating the MFe{sub 2}O{sub 4} (M=Fe, Mn) ferrite shell. Core/shell structured bimagnetic Co/MFe{sub 2}O{sub 4} nanocomposites are prepared with tunable shell thickness (1-5 nm). The Co/MFe{sub 2}O{sub 4} nanocomposites retain the high magnetic moment density from the Co core, while gaining chemical and magnetic stability from the ferrite shell. Compared to Co NPs, the nanocomposites show much enhanced stability in buffer solution at elevated temperatures, making them promising for biomedical applications. - Graphical abstract: The 10 nm/3 nm Co/MFe{sub 2}O{sub 4} (M=Fe, Mn) bimagnetic core/shell nanocomposites are synthesized from the surface coating of ferrite shell over 10 nm Co nanoparticle seeds. The nanocomposites show much enhanced chemical and magnetic stability in solid state, organic solution and aqueous phase, and are promising for biomedical applications.

  3. Random three-dimensional jammed packings of elastic shells acting as force sensors

    NASA Astrophysics Data System (ADS)

    Jose, Jissy; van Blaaderen, Alfons; Imhof, Arnout

    2016-06-01

    In a jammed solid of granular particles, the applied stress is in-homogeneously distributed within the packing. A full experimental characterization requires measurement of all the interparticle forces, but so far such measurements are limited to a few systems in two and even fewer in three dimensions. Particles with the topology of (elastic) shells are good local force sensors as relatively large deformations of the shells result from relatively small forces. We recently introduced such fluorescent shells as a model granular system in which force distributions can be determined in three dimensions using confocal microscopy and quantitative image analysis. An interesting aspect about these shells that differentiates them from other soft deformable particles is their buckling behavior at higher compression. This leads to deformations that do not conserve the inner volume of the particle. Here we use this system to accurately measure the contact forces in a three-dimensional packing of shells subjected to a static anisotropic compression and to shear. At small deformations forces are linear, however, for a buckled contact, the restoring force is related to the amount of deformation by a square root law, as follows from the theory of elasticity of shells. Near the unjamming-jamming transition (point J ), we found the probability distribution of the interparticle forces P (f ) to decay nearly exponentially at large forces, with little evidence of long-range force chains in the packings. As the packing density is increased, the tail of the distribution was found to crossover to a Gaussian, in line with other experimental and simulation studies. Under a small shear strain, up to 0.216, applied at an extremely low shear rate, we observed a shear-induced anisotropy in both the pair correlation function and contact force network; however, no appreciable change was seen in the number of contacts per particle.

  4. Random three-dimensional jammed packings of elastic shells acting as force sensors.

    PubMed

    Jose, Jissy; van Blaaderen, Alfons; Imhof, Arnout

    2016-06-01

    In a jammed solid of granular particles, the applied stress is in-homogeneously distributed within the packing. A full experimental characterization requires measurement of all the interparticle forces, but so far such measurements are limited to a few systems in two and even fewer in three dimensions. Particles with the topology of (elastic) shells are good local force sensors as relatively large deformations of the shells result from relatively small forces. We recently introduced such fluorescent shells as a model granular system in which force distributions can be determined in three dimensions using confocal microscopy and quantitative image analysis. An interesting aspect about these shells that differentiates them from other soft deformable particles is their buckling behavior at higher compression. This leads to deformations that do not conserve the inner volume of the particle. Here we use this system to accurately measure the contact forces in a three-dimensional packing of shells subjected to a static anisotropic compression and to shear. At small deformations forces are linear, however, for a buckled contact, the restoring force is related to the amount of deformation by a square root law, as follows from the theory of elasticity of shells. Near the unjamming-jamming transition (point J), we found the probability distribution of the interparticle forces P(f) to decay nearly exponentially at large forces, with little evidence of long-range force chains in the packings. As the packing density is increased, the tail of the distribution was found to crossover to a Gaussian, in line with other experimental and simulation studies. Under a small shear strain, up to 0.216, applied at an extremely low shear rate, we observed a shear-induced anisotropy in both the pair correlation function and contact force network; however, no appreciable change was seen in the number of contacts per particle. PMID:27415341

  5. Sound Transmission through Two Concentric Cylindrical Sandwich Shells

    NASA Technical Reports Server (NTRS)

    Tang, Yvette Y.; Silcox, Richard J.; Robinson, Jay H.

    1996-01-01

    This paper solves the problem of sound transmission through a system of two infinite concentric cylindrical sandwich shells. The shells are surrounded by external and internal fluid media and there is fluid (air) in the annular space between them. An oblique plane sound wave is incident upon the surface of the outer shell. A uniform flow is moving with a constant velocity in the external fluid medium. Classical thin shell theory is applied to the inner shell and first-order shear deformation theory is applied to the outer shell. A closed form for transmission loss is derived based on modal analysis. Investigations have been made for the impedance of both shells and the transmission loss through the shells from the exterior into the interior. Results are compared for double sandwich shells and single sandwich shells. This study shows that: (1) the impedance of the inner shell is much smaller than that of the outer shell so that the transmission loss is almost the same in both the annular space and the interior cavity of the shells; (2) the two concentric sandwich shells can produce an appreciable increase of transmission loss over single sandwich shells especially in the high frequency range; and (3) design guidelines may be derived with respect to the noise reduction requirement and the pressure in the annular space at a mid-frequency range.

  6. An integrated process to produce ethanol, vanillin, and xylooligosaccharides from Camellia oleifera shell.

    PubMed

    Zhu, Junjun; Zhu, Yuanyuan; Jiang, Faxian; Xu, Yong; Ouyang, Jia; Yu, Shiyuan

    2013-12-15

    This study aims to present an integrated process that can be used to produce ethanol, vanillin, and xylooligosaccharides from Camellia oleifera shell. After the shell was pretreated with NaOH, two fractions were obtained: solid and liquid fractions. The solid fraction was hydrolyzed with cellulase and then fermented with Pichia stipitis to produce ethanol. The liquid fraction was subjected to oxidation to prepare vanillin or hydrolysis with xylanase to prepare xylooligosaccharides. The optimal pretreatment conditions of an orthogonal test were as follows: 12% NaOH concentration; 120°C; 150 min; and liquid-solid ratio of 10.0. After pretreatment, the solid fraction containing cellulose and a small part of xylan at 10% substance concentration via enzymatic hydrolysis and glucose-xylose cofermentation could obtain 17.35 g/L of ethanol, 80.90% of the theoretical yield. The liquid fraction was initially hydrolyzed with xylanase to produce 1758.63 mg/L of xylooligosaccharides (DP2-6) and then oxidized to produce 322.07 mg/L of vanillin. PMID:24188806

  7. An integrated process to produce ethanol, vanillin, and xylooligosaccharides from Camellia oleifera shell.

    PubMed

    Zhu, Junjun; Zhu, Yuanyuan; Jiang, Faxian; Xu, Yong; Ouyang, Jia; Yu, Shiyuan

    2013-12-15

    This study aims to present an integrated process that can be used to produce ethanol, vanillin, and xylooligosaccharides from Camellia oleifera shell. After the shell was pretreated with NaOH, two fractions were obtained: solid and liquid fractions. The solid fraction was hydrolyzed with cellulase and then fermented with Pichia stipitis to produce ethanol. The liquid fraction was subjected to oxidation to prepare vanillin or hydrolysis with xylanase to prepare xylooligosaccharides. The optimal pretreatment conditions of an orthogonal test were as follows: 12% NaOH concentration; 120°C; 150 min; and liquid-solid ratio of 10.0. After pretreatment, the solid fraction containing cellulose and a small part of xylan at 10% substance concentration via enzymatic hydrolysis and glucose-xylose cofermentation could obtain 17.35 g/L of ethanol, 80.90% of the theoretical yield. The liquid fraction was initially hydrolyzed with xylanase to produce 1758.63 mg/L of xylooligosaccharides (DP2-6) and then oxidized to produce 322.07 mg/L of vanillin.

  8. Sub-2-μm seeded growth mesoporous thin shell particles for high-performance liquid chromatography: Synthesis, functionalisation and characterisation.

    PubMed

    Langsi, Victor K; Ashu-Arrah, Benjamin A; Glennon, Jeremy D

    2015-07-10

    Nanometer control over the porous shell thickness of sub-2-μm-shell particles is investigated. Three seeded growth mesoporous thin shell particles for HPLC were prepared, with 0.05μm (or 50nm) porous shell layers: particle sizes 1.5μm (solid core diameters 1.4μm), 1.7μm (solid core diameter 1.6μm), 1.9μm (solid core diameter 1.8μm) and compared with a fourth 1.7μm particle (solid core diameter 1.4μm) surrounded by 0.15μm (or 150nm) porous shell thickness. The thin shell particles were functionalised using a mono-functional octadecyldimethylchlorosilane ligand (C20H43SiCl) under optimised reflux conditions and packed in-house in narrow bore columns (2.1 I.D.×50mm) denoted as TS1.5-50-C18, TS1.7-50-C18, and TS1.9-50-C18 respectively. The synthesised thin shell particles and bonded materials were comprehensively characterised using scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS), zeta potential, BET analysis, elemental analysis (CHN), thermogravimetric analysis (TGA) and diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. Experimental data from inverse size exclusion chromatography (ISEC) was used to measure external, internal and total column porosities. Five probe analytes (uracil, naphthalene, acetophenone, benzene and toluene) were chosen for the chromatographic performance analysis of these columns. Column evaluation and measurements of height equivalent to a theoretical plate (HETP) data were performed on naphthalene using 55% acetonitile in water. The retention coefficients for the thin shell particles (TS1.9-50-C18, TS1.7-50-C18, TS1.5-50-C18) were in the range 1.26-1.35 and 5.6 for the core-shell particle (EiS1.7-150-C18). The minimum reduced plate heights range from 3.89 to 4.26 for the thin shell particles and 2.03 for the core-shell particle.

  9. Cluster aspects of p-shell and sd-shell nuclei

    SciTech Connect

    Kanada-En'yo, Y.; Kobayashi, F.; Suhara, T.; Kimura, M.; Taniguchi, Y.

    2011-05-06

    We report some topics on cluster structures studied by using a theoretical method of antisymmetrized molecular dynamics(AMD). Cluster features of p-shell and sd-shell nuclei are discussed. In particular, three alpha cluster structures in the excited states of {sup 12}C and {sup 14}C are focused. Dineutron correlations in neutron-rich nuclei are also discussed.

  10. Supercooling Self-Assembly of Magnetic Shelled Core/Shell Supraparticles.

    PubMed

    Zheng, Xiaotong; Yan, Bingyun; Wu, Fengluan; Zhang, Jinlong; Qu, Shuxin; Zhou, Shaobing; Weng, Jie

    2016-09-14

    Molecular self-assembly has emerged as a powerful technique for controlling the structure and properties of core/shell structured supraparticles. However, drug-loading capacities and therapeutic effects of self-assembled magnetic core/shell nanocarriers with magnetic nanoparticles in the core are limited by the intervention of the outer organic or inorganic shell, the aggregation of superparamagnetic nanoparticles, the narrowed inner cavity, etc. Here, we present a self-assembly approach based on rebalancing hydrogen bonds between components under a supercooling process to form a new core/shell nanoscale supraparticle with magnetic nanoparticles as the shell and a polysaccharide as a core. Compared with conventional iron oxide nanoparticles, this magnetic shelled core/shell nanoparticle possesses an optimized inner cavity and a loss-free outer magnetic property. Furthermore, we find that the drug-loaded magnetic shelled nanocarriers showed interesting in vitro release behaviors at different pH conditions, including "swelling-broken", "dissociating-broken", and "bursting-broken" modes. Our experiments demonstrate the novel design of the multifunctional hybrid nanostructure and provide a considerable potential for the biomedical applications.

  11. Shell thickness determination of polymer-shelled microbubbles using transmission electron microscopy.

    PubMed

    Härmark, Johan; Hebert, Hans; Koeck, Philip J B

    2016-06-01

    Intravenously injected microbubbles (MBs) can be utilized as ultrasound contrast agent (CA) resulting in enhanced image quality. A novel CA, consisting of air filled MBs stabilized with a shell of polyvinyl alcohol (PVA) has been developed. These spherical MBs have been decorated with superparamagnetic iron oxide nanoparticles (SPIONs) in order to serve as both ultrasound and magnetic resonance imaging (MRI) CA. In this study, a mathematical model was introduced that determined the shell thickness of two types of SPIONs decorated MBs (Type A and Type B). The shell thickness of MBs is important to determine, as it affects the acoustical properties. In order to investigate the shell thickness, thin sections of plastic embedded MBs were prepared and imaged using transmission electron microscopy (TEM). However, the sections were cut at random distances from the MB center, which affected the observed shell thickness. Hence, the model determined the average shell thickness of the MBs from corrected mean values of the outer and inner radii observed in the TEM sections. The model was validated using simulated slices of MBs with known shell thickness and radius. The average shell thickness of Type A and Type B MBs were 651nm and 637nm, respectively.

  12. Modeling shell formation in core-shell nanocrystals in reverse micelle systems.

    PubMed

    Shukla, Diwakar; Mehra, Anurag

    2006-11-01

    The mechanisms responsible for the formation of the shell in core-shell nanocrystals are ion-displacement and heterogeneous nucleation. In the ion-displacement mechanism, the shell is formed by the displacement reaction at the surface of the core nanoparticle whereas in heterogeneous nucleation the core particle induces the nucleation (or direct deposition) of shell material on its surface. The formation of core-shell nanocrystals via the post-core route has been examined in the current investigation. A purely probabilistic Monte Carlo scheme for the formation of the shell has been developed to predict the experimental results of Hota et al. (Hota, G.; Jain, S.; Khilar, K. C. Colloids Surf., A 2004, 232, 119) for the precipitation of Ag2S-coated CdS (Ag2S@CdS) nanoparticles. The simulation procedure involves two stages. In the first stage, shell formation takes place as a result of the consumption of supersaturation, ion displacement, and reaction between Ag+ and excess sulfide ions. The growth in the second stage is driven by the coagulation of nanoparticles. The results indicate that the fraction of shell deposited by the ion-displacement mechanism increases with increasing ion ratio and decreases with increasing water-to-surfactant molar ratio.

  13. Comparative study of the shell development of hard- and soft-shelled turtles

    PubMed Central

    Nagashima, Hiroshi; Shibata, Masahiro; Taniguchi, Mari; Ueno, Shintaro; Kamezaki, Naoki; Sato, Noboru

    2014-01-01

    The turtle shell provides a fascinating model for the investigation of the evolutionary modifications of developmental mechanisms. Different conclusions have been put forth for its development, and it is suggested that one of the causes of the disagreement could be the differences in the species of the turtles used – the differences between hard-shelled turtles and soft-shelled turtles. To elucidate the cause of the difference, we compared the turtle shell development in the two groups of turtle. In the dorsal shell development, these two turtle groups shared the gene expression profile that is required for formation, and shared similar spatial organization of the anatomical elements during development. Thus, both turtles formed the dorsal shell through a folding of the lateral body wall, and the Wnt signaling pathway appears to have been involved in the development. The ventral portion of the shell, on the other hand, contains massive dermal bones. Although expression of HNK-1 epitope has suggested that the trunk neural crest contributed to the dermal bones in the hard-shelled turtles, it was not expressed in the initial anlage of the skeletons in either of the types of turtle. Hence, no evidence was found that would support a neural crest origin. PMID:24754673

  14. Comparative study of the shell development of hard- and soft-shelled turtles.

    PubMed

    Nagashima, Hiroshi; Shibata, Masahiro; Taniguchi, Mari; Ueno, Shintaro; Kamezaki, Naoki; Sato, Noboru

    2014-07-01

    The turtle shell provides a fascinating model for the investigation of the evolutionary modifications of developmental mechanisms. Different conclusions have been put forth for its development, and it is suggested that one of the causes of the disagreement could be the differences in the species of the turtles used - the differences between hard-shelled turtles and soft-shelled turtles. To elucidate the cause of the difference, we compared the turtle shell development in the two groups of turtle. In the dorsal shell development, these two turtle groups shared the gene expression profile that is required for formation, and shared similar spatial organization of the anatomical elements during development. Thus, both turtles formed the dorsal shell through a folding of the lateral body wall, and the Wnt signaling pathway appears to have been involved in the development. The ventral portion of the shell, on the other hand, contains massive dermal bones. Although expression of HNK-1 epitope has suggested that the trunk neural crest contributed to the dermal bones in the hard-shelled turtles, it was not expressed in the initial anlage of the skeletons in either of the types of turtle. Hence, no evidence was found that would support a neural crest origin.

  15. Simplified dispersion curves for circular cylindrical shells using shallow shell theory

    NASA Astrophysics Data System (ADS)

    Sarkar, Abhijit; Sonti, Venkata R.

    2009-04-01

    An alternative derivation of the dispersion relation for the transverse vibration of a circular cylindrical shell is presented. The use of the shallow shell theory model leads to a simpler derivation of the same result. Further, the applicability of the dispersion relation is extended to the axisymmetric mode and the high frequency beam mode.

  16. SolidShperal

    2013-12-22

    SolidSpheral is an extension of the Spheral open source meshless hydrodynamics method. SolidSpheral adds the capability to model solid materials using analytic equations of state, and a simple damage model to allow for the modeled materials to undergo dynamic damage evolution. SolidSpheral is a distributed parallel code employing MPI for the parallel framework.

  17. Shell-in-Shell TiO2 hollow microspheres and optimized application in light-trapping perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Sun, Hongxia; Ruan, Peng; Bao, Zhongqiu; Chen, Lei; Zhou, Xingfu

    2015-02-01

    The shell-in-shell structured TiO2 hollow microspheres with enhanced light scattering ability were synthesized via a facile one step hydrothermal process. The diameter of the microsphere is about 1.5 μm, the core of the unique shell-in-shell structure is composed of TiO2 nanoparticles with a diameter of about 15 nm, while the shell is constructed with ∼50 nm TiO2 nanocubes. The hollow space between the outer shell and the inner shell is about 230 nm. The formation mechanism of the unique shell-in-shell structure is interpreted. The design and the optimized application of shell-in-shell structured TiO2 hollow microspheres in the light-trapping perovskite solar cells are also investigated. Owing to the light scattering properties of the shell-in-shell structure of the hollow microsphere, the optimized photoelectrode exhibits an enhanced photoelectric conversion efficiency of 4.29% using perovskite CH3NH3PbI3 as the sensitizer. The shell-in-shell hollow TiO2 microsphere shows a 21.2% increase in conversion efficiency when compared with P25 nanoparticels photoanode. The conversion efficiency enhancement is mainly attributed to the increase of short-current density induced by the light scattering effect.

  18. Exocomet signatures around the A-shell star φ Leonis?

    NASA Astrophysics Data System (ADS)

    Eiroa, C.; Rebollido, I.; Montesinos, B.; Villaver, E.; Absil, O.; Henning, Th.; Bayo, A.; Canovas, H.; Carmona, A.; Chen, Ch.; Ertel, S.; Iglesias, D. P.; Launhardt, R.; Maldonado, J.; Meeus, G.; Moór, A.; Mora, A.; Mustill, A. J.; Olofsson, J.; Riviere-Marichalar, P.; Roberge, A.

    2016-10-01

    We present an intensive monitoring of high-resolution spectra of the Ca ii K line in the A7IV shell star φ Leo at very short (minutes, hours), short (night to night), and medium (weeks, months) timescales. The spectra show remarkable variable absorptions on timescales of hours, days, and months. The characteristics of these sporadic events are very similar to most that are observed toward the debris disk host star β Pic, which are commonly interpreted as signs of the evaporation of solid, comet-like bodies grazing or falling onto the star. Therefore, our results suggest the presence of solid bodies around φ Leo. To our knowledge, with the exception of β Pic, our monitoring has the best time resolution at the mentioned timescales for a star with events attributed to exocomets. Assuming the cometary scenario and considering the timescales of our monitoring, our results indicate that φ Leo presents the richest environment with comet-like events known to date, second only to β Pic.

  19. Size-selective yolk-shell nanoreactors with nanometer-thin porous polymer shells.

    PubMed

    Jia, Ying; Shmakov, Sergey N; Register, Paul; Pinkhassik, Eugene

    2015-09-01

    Yolk-shell nanoreactors with metal nanoparticle core and ultrathin porous polymer shells are effective catalysts for heterogeneous reactions. Polymer shells provide size-selectivity and improved reusability of catalyst. Nanocapsules with single-nanometer porous shells are prepared by vesicle-templated directed assembly. Metal nanoparticles are formed either by selective initiation in pre-fabricated nanocapsules or simultaneously with the creation of a crosslinked polymer shell. In this study, we investigated the oxidation of benzyl alcohol and benzaldehyde catalyzed by gold nanoparticles and hydrogenation of cyclohexene catalyzed by platinum nanoparticles. Comparison of newly created nanoreactors with commercially available nanoparticles revealed superior reusability and size selectivity in nanoreactors while showing no negative effect on reaction kinetics.

  20. Solids fluidizer-injector

    DOEpatents

    Bulicz, Tytus R.

    1990-01-01

    An apparatus and process for fluidizing solid particles by causing rotary motion of the solid particles in a fluidizing chamber by a plurality of rotating projections extending from a rotatable cylinder end wall interacting with a plurality of fixed projections extending from an opposite fixed end wall and passing the solid particles through a radial feed orifice open to the solids fluidizing chamber on one side and a solid particle utilization device on the other side. The apparatus and process are particularly suited for obtaining intermittent feeding with continual solids supply to the fluidizing chamber. The apparatus and process are suitable for injecting solid particles, such as coal, to an internal combustion engine.

  1. Dynamics of dusty radiation-pressure-driven shells and clouds: fast outflows from galaxies, star clusters, massive stars, and AGN

    NASA Astrophysics Data System (ADS)

    Thompson, Todd A.; Fabian, Andrew C.; Quataert, Eliot; Murray, Norman

    2015-05-01

    It is typically assumed that radiation-pressure-driven winds are accelerated to an asymptotic velocity of v∞ ≃ vesc, where vesc is the escape velocity from the central source. We note that this is not the case for dusty shells and clouds. Instead, if the shell or cloud is initially optically thick to the UV emission from the source of luminosity L, then there is a significant boost in v∞ that reflects the integral of the momentum absorbed as it is accelerated. For shells reaching a generalized Eddington limit, we show that v∞ ≃ (4RUVL/Mshc)1/2, in both point-mass and isothermal-sphere potentials, where RUV is the radius where the shell becomes optically thin to UV photons, and Msh is the mass of the shell. The asymptotic velocity significantly exceeds vesc for typical parameters, and can explain the ˜1000-2000 km s-1 outflows observed from rapidly star-forming galaxies and active galactic nuclei (AGN) if the surrounding halo has low gas density. Similarly fast outflows from massive stars can be accelerated on ˜few-103 yr time-scales. These results carry over to clouds that subtend only a small fraction of the solid angle from the source of radiation and that expand as a consequence of their internal sound speed. We further consider the dynamics of shells that sweep up a dense circumstellar or circumgalactic medium. We calculate the `momentum ratio' dot{M} v/(L/c) in the shell limit and show that it can only significantly exceed ˜2 if the effective optical depth of the shell to re-radiated far-infrared photons is much larger than unity. We discuss simple prescriptions for the properties of galactic outflows for use in large-scale cosmological simulations. We also briefly discuss applications to the dusty ejection episodes of massive stars, the disruption of giant molecular clouds, and AGN.

  2. Mesoporous core–shell Fenton nanocatalyst: a mild, operationally simple approach to the synthesis of adipic acid.

    PubMed

    Patra, Astam K; Dutta, Arghya; Bhaumik, Asim

    2013-09-01

    Mesoporous nanoparticles composed of γ-Al2O3 cores and α-Fe2O3 shells were synthesized in aqueous medium. The surface charge of γ-Al2O3 helps to form the core–shell nanocrystals. The core–shell structure and formation mechanism have been investigated by wide-angle XRD, energy-dispersive X-ray spectroscopy, and elemental mapping by ultrahigh-resolution (UHR) TEM and X-ray photoelectron spectroscopy. The N2 adsorption–desorption isotherm of this core–shell materials, which is of type IV, is characteristic of a mesoporous material having a BET surface area of 385 m2 g(−1) and an average pore size of about 3.2 nm. The SEM images revealed that the mesoporosity in this core–shell material is due to self-aggregation of tiny spherical nanocrystals with sizes of about 15–20 nm. Diffuse-reflectance UV/Vis spectra, elemental mapping by UHRTEM, and wide-angle XRD patterns indicate that the materials are composed of aluminum oxide cores and iron oxide shells. These Al2O3@Fe2O3 core–shell nanoparticles act as a heterogeneous Fenton nanocatalyst in the presence of hydrogen peroxide, and show high catalytic efficiency for the one-pot conversion of cyclohexanone to adipic acid in water. The heterogeneous nature of the catalyst was confirmed by a hot filtration test and analysis of the reaction mixture by atomic absorption spectroscopy. The kinetics of the reaction was monitored by gas chromatography and 1H NMR spectroscopy. The new core–shell catalyst remained in a separate solid phase, which could easily be removed from the reaction mixture by simple filtration and the catalyst reused efficiently.

  3. Mesoporous core–shell Fenton nanocatalyst: a mild, operationally simple approach to the synthesis of adipic acid.

    PubMed

    Patra, Astam K; Dutta, Arghya; Bhaumik, Asim

    2013-09-01

    Mesoporous nanoparticles composed of γ-Al2O3 cores and α-Fe2O3 shells were synthesized in aqueous medium. The surface charge of γ-Al2O3 helps to form the core–shell nanocrystals. The core–shell structure and formation mechanism have been investigated by wide-angle XRD, energy-dispersive X-ray spectroscopy, and elemental mapping by ultrahigh-resolution (UHR) TEM and X-ray photoelectron spectroscopy. The N2 adsorption–desorption isotherm of this core–shell materials, which is of type IV, is characteristic of a mesoporous material having a BET surface area of 385 m2 g(−1) and an average pore size of about 3.2 nm. The SEM images revealed that the mesoporosity in this core–shell material is due to self-aggregation of tiny spherical nanocrystals with sizes of about 15–20 nm. Diffuse-reflectance UV/Vis spectra, elemental mapping by UHRTEM, and wide-angle XRD patterns indicate that the materials are composed of aluminum oxide cores and iron oxide shells. These Al2O3@Fe2O3 core–shell nanoparticles act as a heterogeneous Fenton nanocatalyst in the presence of hydrogen peroxide, and show high catalytic efficiency for the one-pot conversion of cyclohexanone to adipic acid in water. The heterogeneous nature of the catalyst was confirmed by a hot filtration test and analysis of the reaction mixture by atomic absorption spectroscopy. The kinetics of the reaction was monitored by gas chromatography and 1H NMR spectroscopy. The new core–shell catalyst remained in a separate solid phase, which could easily be removed from the reaction mixture by simple filtration and the catalyst reused efficiently. PMID:24167824

  4. Solids mass flow determination

    DOEpatents

    Macko, Joseph E.

    1981-01-01

    Method and apparatus for determining the mass flow rate of solids mixed with a transport fluid to form a flowing mixture. A temperature differential is established between the solids and fluid. The temperature of the transport fluid prior to mixing, the temperature of the solids prior to mixing, and the equilibrium temperature of the mixture are monitored and correlated in a heat balance with the heat capacities of the solids and fluid to determine the solids mass flow rate.

  5. Thick or Thin Ice Shell on Europa?

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Scientists are all but certain that Europa has an ocean underneath its icy surface, but they do not know how thick this ice might be. This artist concept illustrates two possible cut-away views through Europa's ice shell. In both, heat escapes, possibly volcanically, from Europa's rocky mantle and is carried upward by buoyant oceanic currents. If the heat from below is intense and the ice shell is thin enough (left), the ice shell can directly melt, causing what are called 'chaos' on Europa, regions of what appear to be broken, rotated and tilted ice blocks. On the other hand, if the ice shell is sufficiently thick (right), the less intense interior heat will be transferred to the warmer ice at the bottom of the shell, and additional heat is generated by tidal squeezing of the warmer ice. This warmer ice will slowly rise, flowing as glaciers do on Earth, and the slow but steady motion may also disrupt the extremely cold, brittle ice at the surface. Europa is no larger than Earth's moon, and its internal heating stems from its eccentric orbit about Jupiter, seen in the distance. As tides raised by Jupiter in Europa's ocean rise and fall, they may cause cracking, additional heating and even venting of water vapor into the airless sky above Europa's icy surface. (Artwork by Michael Carroll.)

  6. Hollow Pollen Shells to Enhance Drug Delivery

    PubMed Central

    Diego-Taboada, Alberto; Beckett, Stephen T.; Atkin, Stephen L.; Mackenzie, Grahame

    2014-01-01

    Pollen grain and spore shells are natural microcapsules designed to protect the genetic material of the plant from external damage. The shell is made up of two layers, the inner layer (intine), made largely of cellulose, and the outer layer (exine), composed mainly of sporopollenin. The relative proportion of each varies according to the plant species. The structure of sporopollenin has not been fully characterised but different studies suggest the presence of conjugated phenols, which provide antioxidant properties to the microcapsule and UV (ultraviolet) protection to the material inside it. These microcapsule shells have many advantageous properties, such as homogeneity in size, resilience to both alkalis and acids, and the ability to withstand temperatures up to 250 °C. These hollow microcapsules have the ability to encapsulate and release actives in a controlled manner. Their mucoadhesion to intestinal tissues may contribute to the extended contact of the sporopollenin with the intestinal mucosa leading to an increased efficiency of delivery of nutraceuticals and drugs. The hollow microcapsules can be filled with a solution of the active or active in a liquid form by simply mixing both together, and in some cases operating a vacuum. The active payload can be released in the human body depending on pressure on the microcapsule, solubility and/or pH factors. Active release can be controlled by adding a coating on the shell, or co-encapsulation with the active inside the shell. PMID:24638098

  7. Folding of non-Euclidean curved shells

    NASA Astrophysics Data System (ADS)

    Bende, Nakul; Evans, Arthur; Innes-Gold, Sarah; Marin, Luis; Cohen, Itai; Santangelo, Christian; Hayward, Ryan

    2015-03-01

    Origami-based folding of 2D sheets has been of recent interest for a variety of applications ranging from deployable structures to self-folding robots. Though folding of planar sheets follows well-established principles, folding of curved shells involves an added level of complexity due to the inherent influence of curvature on mechanics. In this study, we use principles from differential geometry and thin shell mechanics to establish fundamental rules that govern folding of prototypical creased shells. In particular, we show how the normal curvature of a crease line controls whether the deformation is smooth or discontinuous, and investigate the influence of shell thickness and boundary conditions. We show that snap-folding of shells provides a route to rapid actuation on time-scales dictated by the speed of sound. The simple geometric design principles developed can be applied at any length-scale, offering potential for bio-inspired soft actuators for tunable optics, microfluidics, and robotics. This work was funded by the National Science Foundation through EFRI ODISSEI-1240441 with additional support to S.I.-G. through the UMass MRSEC DMR-0820506 REU program.

  8. Removable inner turbine shell with bucket tip clearance control

    DOEpatents

    Sexton, Brendan F.; Knuijt, Hans M.; Eldrid, Sacheverel Q.; Myers, Albert; Coneybeer, Kyle E.; Johnson, David Martin; Kellock, Iain R.

    2000-01-01

    A turbine includes a plurality of inner shell sections mounting first and second stage nozzle and shroud portions. The inner shell sections are pinned to an outer containment shell formed of sections to preclude circumferential movement of the inner shell relative to the outer shell and enable thermal expansion and contraction of the inner shell relative to the outer shell. Positive bucket tip clearance control is afforded by passing a thermal medium about the inner shell in heat transfer relation with the shrouds about the first and second stage bucket tips, the thermal medium being provided from a source of heating/cooling fluid independent of the turbine. Access is provided to the rotor and turbine buckets by removing the outer and inner shell sections.

  9. Structural Assessment of Advanced Composite Tow-Steered Shells

    NASA Technical Reports Server (NTRS)

    Wu, K. Chauncey; Stanford, Bret K.; Hrinda, Glenn A.; Wang, Zhuosong; Martin, Robert a.; Kim, H. Alicia

    2013-01-01

    The structural performance of two advanced composite tow-steered shells, manufactured using a fiber placement system, is assessed using both experimental and analytical methods. The fiber orientation angles vary continuously around the shell circumference from 10 degrees on the shell crown and keel, to 45 degrees on the shell sides. The two shells differ in that one shell has the full 24-tow course applied during each pass of the fiber placement system, while the second shell uses the fiber placement system s tow drop/add capability to achieve a more uniform shell wall thickness. The shells are tested in axial compression, and estimates of their prebuckling axial stiffnesses and bifurcation buckling loads are predicted using linear finite element analyses. These preliminary predictions compare well with the test results, with an average agreement of approximately 10 percent.

  10. Analysis of two colliding fractionally damped spherical shells in modelling blunt human head impacts

    NASA Astrophysics Data System (ADS)

    Rossikhin, Yury A.; Shitikova, Marina V.

    2013-06-01

    The collision of two elastic or viscoelastic spherical shells is investigated as a model for the dynamic response of a human head impacted by another head or by some spherical object. Determination of the impact force that is actually being transmitted to bone will require the model for the shock interaction of the impactor and human head. This model is indended to be used in simulating crash scenarios in frontal impacts, and provide an effective tool to estimate the severity of effect on the human head and to estimate brain injury risks. The model developed here suggests that after the moment of impact quasi-longitudinal and quasi-transverse shock waves are generated, which then propagate along the spherical shells. The solution behind the wave fronts is constructed with the help of the theory of discontinuities. It is assumed that the viscoelastic features of the shells are exhibited only in the contact domain, while the remaining parts retain their elastic properties. In this case, the contact spot is assumed to be a plane disk with constant radius, and the viscoelastic features of the shells are described by the fractional derivative standard linear solid model. In the case under consideration, the governing differential equations are solved analytically by the Laplace transform technique. It is shown that the fractional parameter of the fractional derivative model plays very important role, since its variation allows one to take into account the age-related changes in the mechanical properties of bone.

  11. Crab shell-based biosorption technology for the treatment of nickel-bearing electroplating industrial effluents.

    PubMed

    Vijayaraghavan, K; Palanivelu, K; Velan, M

    2005-03-17

    This paper discusses the possible application of a biosorption system with acid-washed crab shells in a packed bed up-flow column for the removal of nickel from electroplating industrial effluents. Between two nickel-bearing effluents, effluent-1 is characterized by considerable amount of light metals along with trace amounts of lead and copper. Effluent-2 is characterized by relatively low conductivity, total dissolved solids and total hardness compared to effluent-1. Crab shells exhibited uptakes of 15.08 and 20.04 mg Ni/g from effluent-1 and effluent-2, respectively. The crab shell bed was regenerated using 0.01 M EDTA (pH 9.8, aq. NH3) and reused for seven sorption-desorption cycles. The EDTA elution provided elution efficiencies up to 99% in all the seven cycles. This, together with the data from regeneration efficiencies for seven cycles, provided evidence that the reusability of crab shell in the treatment of nickel-bearing electroplating industrial effluents is viable.

  12. Mesoscale morphology of airborne core-shell nanoparticle clusters: x-ray laser coherent diffraction imaging

    NASA Astrophysics Data System (ADS)

    Pedersoli, E.; Loh, N. D.; Capotondi, F.; Y Hampton, C.; Sierra, R. G.; Starodub, D.; Bostedt, C.; Bozek, J.; Nelson, A. J.; Aslam, M.; Li, S.; Dravid, V. P.; Martin, A. V.; Aquila, A.; Barty, A.; Fleckenstein, H.; Gumprecht, L.; Liang, M.; Nass, K.; Schulz, J.; White, T. A.; Coppola, N.; Bajt, S.; Barthelmess, M.; Graafsma, H.; Hirsemann, H.; Wunderer, C.; Epp, S. W.; Erk, B.; Rudek, B.; Rudenko, A.; Foucar, L.; Kassemeyer, S.; Lomb, L.; Rolles, D.; Shoeman, R. L.; Steinbrener, J.; Hartmann, R.; Hartmann, A.; Hauser, G.; Holl, P.; Kimmel, N.; Reich, C.; Soltau, H.; Weidenspointner, G.; Benner, W. H.; Farquar, G. R.; Hau-Riege, S. P.; Hunter, M. S.; Ekeberg, T.; Hantke, M.; Maia, F. R. N. C.; Tobias, H. J.; Marchesini, S.; Frank, M.; Strüder, L.; Schlichting, I.; Ullrich, J.; Chapman, H. N.; Bucksbaum, P. H.; Kiskinova, M.; Bogan, M. J.

    2013-08-01

    Unraveling the complex morphology of functional materials like core-shell nanoparticles and its evolution in different environments is still a challenge. Only recently has the single-particle coherent diffraction imaging (CDI), enabled by the ultrabright femtosecond free-electron laser pulses, provided breakthroughs in understanding mesoscopic morphology of nanoparticulate matter. Here, we report the first CDI results for Co@SiO2 core-shell nanoparticles randomly clustered in large airborne aggregates, obtained using the x-ray free-electron laser at the Linac Coherent Light Source. Our experimental results compare favourably with simulated diffraction patterns for clustered Co@SiO2 nanoparticles with ˜10 nm core diameter and ˜30 nm shell outer diameter, which confirms the ability to resolve the mesoscale morphology of complex metastable structures. The findings in this first morphological study of core-shell nanomaterials are a solid base for future time-resolved studies of dynamic phenomena in complex nanoparticulate matter using x-ray lasers.

  13. Crab shell-based biosorption technology for the treatment of nickel-bearing electroplating industrial effluents.

    PubMed

    Vijayaraghavan, K; Palanivelu, K; Velan, M

    2005-03-17

    This paper discusses the possible application of a biosorption system with acid-washed crab shells in a packed bed up-flow column for the removal of nickel from electroplating industrial effluents. Between two nickel-bearing effluents, effluent-1 is characterized by considerable amount of light metals along with trace amounts of lead and copper. Effluent-2 is characterized by relatively low conductivity, total dissolved solids and total hardness compared to effluent-1. Crab shells exhibited uptakes of 15.08 and 20.04 mg Ni/g from effluent-1 and effluent-2, respectively. The crab shell bed was regenerated using 0.01 M EDTA (pH 9.8, aq. NH3) and reused for seven sorption-desorption cycles. The EDTA elution provided elution efficiencies up to 99% in all the seven cycles. This, together with the data from regeneration efficiencies for seven cycles, provided evidence that the reusability of crab shell in the treatment of nickel-bearing electroplating industrial effluents is viable. PMID:15752873

  14. Do freshwater mussel shells record road-salt pollution?

    PubMed Central

    O'Neil, Dane D.; Gillikin, David P.

    2014-01-01

    Road-salt pollution in streams in the Northeastern United States has become a major concern, but historical data are scarce. Freshwater bivalve shells have the ability to record past environmental information, and may act as archives of road-salt pollution. We sampled Elliptio complanata shells from four streams, as well as specimens collected in 1877. Average [Na/Ca]shell was highest in modern shells from the stream with the highest sodium concentrations, and low in shells collected from this same stream in 1877 as well as in the shells from other streams, suggesting that [Na/Ca]shell serves as a proxy for road-salt pollution. We expected higher [Na/Ca]shell in winter and spring. However, high-resolution [Na/Ca]shell analyses along the growth axis of one shell did not reveal any clear subannual patterns, which could be the result of shell growth cessation in winter and/or during periods of high stream sodium concentrations. Therefore, bulk [Na/Ca]shell analysis from multiple shells can be used as a proxy of large changes in stream sodium concentrations, but high-resolution variations in stream sodium concentrations do not seem to be recorded in the shells. PMID:25418687

  15. Synthesis of fluorescent core-shell nanomaterials and strategies to generate white light

    SciTech Connect

    Singh, Amandeep; Kaur, Ramanjot; Pandey, O. P.; Wei, Xueyong; Sharma, Manoj E-mail: manojsharma@bilkent.edu.tr

    2015-07-28

    In this work, cadmium free core-shell ZnS:X/ZnS (X = Mn, Cu) nanoparticles have been synthesized and used for white light generation. First, the doping concentration of Manganese (Mn) was varied from 1% to 4% to optimize the dopant related emission and its optimal value was found to be 1%. Then, ZnS shell was grown over ZnS:Mn(1%) core to passivate the surface defects. Similarly, the optimal concentration of Copper (Cu) was found to be 0.8% in the range varied from 0.6% to 1.2%. In order to obtain an emission in the whole visible spectrum, dual doping of Mn and Cu was done in the core and the shell, respectively. A solid-solid mixing in different ratios of separately doped quantum dots (QDs) emitting in the blue green and the orange region was performed. Results show that the optimum mixture of QDs excited at 300 nm gives Commission Internationale del'Éclairage color coordinates of (0.35, 0.36), high color rendering index of 88, and correlated color temperature of 4704 K with minimum self-absorption.

  16. Evaporation of multi-component mixtures and shell formation in spray dried droplets

    NASA Astrophysics Data System (ADS)

    Valente, Pedro; Duarte, Íris; Porfirio, Tiago; Temtem, Márcio

    2015-11-01

    Drug particles where the active pharmaceutical ingredient (APIs) is dispersed in a polymer matrix forming an amorphous solid dispersion (ASD) is a commonly used strategy to increase the solubility and dissolution rate of poorly water soluble APIs. However, the formation and stability of an amorphous solid dispersion depends on the polymer/API combination and process conditions to generate it. The focus of the present work is to further develop a numerical tool to predict the formation of ASDs by spray drying solutions of different polymer/API combinations. Specifically, the evaporation of a multi-component droplet is coupled with a diffusion law within the droplet that minimizes the Gibbs free energy of the polymer/API/solvents system, following the Flory-Huggins model. Prior to the shell formation, the evaporation of the solvents is modelled following the simplified approach proposed by Abramzon & Sirignano (1989) which accounts for the varying relative velocity between the droplet and the drying gas. After shell formation, the diffusion of the solvents across the porous shell starkly modifies the evaporative dynamics.

  17. Tuning of whispering gallery modes of polymeric micro-spheres and shells using external electric field

    NASA Astrophysics Data System (ADS)

    Ioppolo, Tindaro; Ayaz, Ulas; Ötügen, M. Volkan

    2010-02-01

    The electrostriction effect on the whispering gallery modes (WGM) of polymeric micro-spheres is investigated analytically and experimentally. Electrostriction is the elastic deformation (mechanical strain) of a dielectric material due the force exerted by an electric field. The elastic deformation also leads to mechanical stress which perturbs the refractive index of the sphere. Both if these effects (strain and stress) induce a shift in the WGM of the dielectric microsphere. We develop analytical expressions for the WGM shift due to electrostriction for solid and thin-walled micro-shells. The analytical results show that detection of electric fields < 1000 V/m is possible using water filled PDMS microshells. The electric field sensitivities for solid spheres, on the other hand, are significantly smaller. Results of experiments carried out using solid polydimethylsiloxane (PDMS) spheres agree well with the analytical prediction. These results are encouraging for future development of WGM-based optical switches/filters as well as electric field sensors.

  18. Nova shell observation of V2275 Cyg

    NASA Astrophysics Data System (ADS)

    Esenoglu, Hasan H.; Balman, Solen; Saygac, A. Talat

    2016-07-01

    We present a recent search for nova shell of V2275 Cyg after its eruption of 9 years, using narrow bands of H-alpha, OIII and H-alpha-continuum images taken with RTT150 telescope at TUG. They were taken in November 2nd, 2010 with exposures of 600sec. There is uncertain in the literature whether the nova shell is visible in H-alpha. In this work the nova disappears on frame of OIII (wavelengt of 500.7nm with band width of 5nm) when it is faint apparent on the frames of both H-alpha and H-alpha continuum. We will calculate a new angular diameter of the nova shell by using the nebular expantion method if the data allow to measure seeing values of the nova and neighbor stars.

  19. Shell nebulae around luminous evolved stars

    NASA Technical Reports Server (NTRS)

    Dufour, Reginald J.

    1989-01-01

    Shell nebulae around luminous Population I Wolf-Rayet, Of, and P-Cygni stars are astrophysically interesting since they are indicators of pre-supernova mass loss and how such massive stars prepare their surrounding interstellar medium prior to explosion. Some twenty-odd such nebulae are known, for which detailed study of their morphological and spectroscopic characteristics have only begun in this decade. In this paper, some of these characteristics are reviewed in general, and new observations are reported. Emphasis has been placed on several 'prototype 'objects (NGC 7635, NGC 2359, NGC 6888, and the Eta Carinae condensations) to illustrate the varied massive-star mass-loss, the physics of their winds and shell ejecta, and related nucleosynthesis effects in the compositions of the winds and shells.

  20. Shape-changing shell-like structures.

    PubMed

    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.

  1. Brachiopod punctae: a complexity in shell biomineralisation.

    PubMed

    Pérez-Huerta, A; Cusack, M; McDonald, S; Marone, F; Stampanoni, M; MacKay, S

    2009-07-01

    Perforations ("punctae") are one of the most characteristic morphological shell features in calcite brachiopods. The significance of punctae is that they represent discontinuities in shell biomineralisation and thus add a level of complexity that must be accounted for in any model of brachiopod shell formation. A significant hindrance to understanding punctae growth and formation is the absence of sufficient information on volume, size and density. Here, we use synchrotron-radiation X-ray tomographic microscopy (SRXTM) to obtain three-dimensional information about punctae of five species of calcite brachiopods. X-ray tomography shows that punctae morphology is species-specific and reveals previously unknown levels of complexity for each species. This information is combined with previous data on morphology to discuss the function and growth of punctae. Overall the present study demonstrates the need to increase our understanding of discontinuities and the role of cell biology in the context of biomineralisation.

  2. Locally adaptive method to define coordination shell

    NASA Astrophysics Data System (ADS)

    Higham, Jonathan; Henchman, Richard H.

    2016-08-01

    An algorithm is presented to define a particle's coordination shell for any collection of particles. It requires only the particles' positions and no pre-existing knowledge or parameters beyond those already in the force field. A particle's shell is taken to be all particles that are not blocked by any other particle and not further away than a blocked particle. Because blocking is based on two distances and an angle for triplets of particles, it is called the relative angular distance (RAD) algorithm. RAD is applied to Lennard-Jones particles in molecular dynamics simulations of crystalline, liquid, and gaseous phases at various temperatures and densities. RAD coordination shells agree well with those from a cut-off in the radial distribution function for the crystals and liquids and are slightly higher for the gas.

  3. Locally adaptive method to define coordination shell.

    PubMed

    Higham, Jonathan; Henchman, Richard H

    2016-08-28

    An algorithm is presented to define a particle's coordination shell for any collection of particles. It requires only the particles' positions and no pre-existing knowledge or parameters beyond those already in the force field. A particle's shell is taken to be all particles that are not blocked by any other particle and not further away than a blocked particle. Because blocking is based on two distances and an angle for triplets of particles, it is called the relative angular distance (RAD) algorithm. RAD is applied to Lennard-Jones particles in molecular dynamics simulations of crystalline, liquid, and gaseous phases at various temperatures and densities. RAD coordination shells agree well with those from a cut-off in the radial distribution function for the crystals and liquids and are slightly higher for the gas. PMID:27586905

  4. Working and Net Available Shell Storage Capacity

    EIA Publications

    2016-01-01

    Working and Net Available Shell Storage Capacity is the U.S. Energy Information Administration’s (EIA) report containing storage capacity data for crude oil, petroleum products, and selected biofuels. The report includes tables detailing working and net available shell storage capacity by type of facility, product, and Petroleum Administration for Defense District (PAD District). Net available shell storage capacity is broken down further to show the percent for exclusive use by facility operators and the percent leased to others. Crude oil storage capacity data are also provided for Cushing, Oklahoma, an important crude oil market center. Data are released twice each year near the end of May (data for March 31) and near the end of November (data for September 30).

  5. FInal Report - Investment Casting Shell Cracking

    SciTech Connect

    Von Richards

    2003-12-01

    This project made a significant contribution to the understanding of the investment casting shell cracking problem. The effects of wax properties on the occurrence of shell cracking were demonstrated and can be measured. The properties measured include coefficient of thermal expansion, heating rate and crystallinity of the structure. The important features of production molds and materials properties have been indicated by case study analysis and fractography of low strength test bars. It was found that stress risers in shell cavity design were important and that typical critical flaws were either oversize particles or large pores just behind the prime coat. It was also found that the true effect of fugitive polymer fibers was not permeability increase, but rather a toughening mechanism due to crack deflection.

  6. Shells on nanowires detected by analytical TEM

    NASA Astrophysics Data System (ADS)

    Thomas, Jürgen; Gemming, Thomas

    2005-09-01

    Nanostructures in the form of nanowires or filled nanotubes and nanoparticles covered by shells are of great interest in materials science. They allow the creation of new materials with tailored new properties. For the characterisation of these structures and their shells by means of analytical transmission electron microscopy (TEM), especially by energy dispersive X-ray spectroscopy (EDXS), and electron energy loss spectroscopy (EELS), the accurate analysis of linescan intensity profiles is necessary. A mathematical model is described, which is suitable for this analysis. It considers the finite electron beam size, the beam convergence, and the beam broadening within the specimen. It is shown that the beam size influences the measured result of core radius and shell thickness. On the other hand, the influence of the beam broadening within the specimen is negligible. At EELS, the specimen thickness must be smaller than the mean free path for inelastic scattering. Otherwise, artifacts of the signal profile of a nanowire can pretend a nanotube.

  7. The microindentation behavior of several mollusk shells

    SciTech Connect

    Laraia, V.J.; Heuer, A.H. . Dept. of Materials Science and Engineering)

    1990-01-01

    An investigation of the relationship between structure and mechanical behavior is reported for mollusk shells employing foliated, nacreous, and crossed-lamellar structures by microindentation in the Knoop and Vickers geometries. Indentation damage zones develop crack systems that reflect the micro-architecture. For the crosed-lamellar structure, the system of cracks about the indentation normally developed in a brittle material is suppressed. Previous reports that shells are harder than the corresponding minerals, calcite and aragonite, are confirmed, but it is found that this effect can be strongly dependent on orientation. This anomalous hardness is not an artifact of the indentation test technique, since scratch tests confirm the relative hardness of shell over the mineral. It is suggested that microstructural organization is of central importance in producing this hardness, as opposed to intrinsic properties of the mineral or matrix phases. 17 refs., 6 figs., 1 tab.

  8. Stresses in rotating composite cylindrical shells

    NASA Astrophysics Data System (ADS)

    Wang, James T.-S.; Lin, Chien-Chang

    Stresses in composite cylindrical shells rotating with a constant speed about their longitudinal axis are analyzed. Each ply or ply group is treated as a separate thin layer of homogeneous and orthotropic material under the interfacial stresses as surface loading. There is no limitation on the total thickness of the shell. The circumferential stress, motivated by the conventional thin shell theory, is assumed to vary linearly through the thickness of the layer. The radial stress is determined in terms of the circumferential stress through the equilibrium condition, and an average compatibility condition through the thickness of the thin layer is used. Numerical results using the present analysis show nearly perfect agreement with the exact solution for homogeneous and isotropic cylinders. Some results for cylinders having orthotropic layers are presented for illustrative purposes.

  9. COMPLETE SURFACE MAPPING OF ICF SHELLS

    SciTech Connect

    STEPHENS,R.B; OLSON,D; HUANG,H; GIBSON,J.B

    2003-06-01

    OAK-B135 Inertial confinement fusion shells have previously been evaluated on the basis of microscopic examination for local defects and limited surface profiling to represent their average fluctuation power. Since defects are local, and don't always have visible edges, this approach both misses some important fluctuations and doesn't properly represent the spatially dependent surface fluctuation power. they have taken the first step toward correcting this problem by demonstrating the capability to completely map the surface of a NIF shell with the resolution to account for all modes. This allows complete accounting of all the surface fluctuations. In the future this capability could be used for valuable shells to generate a complete r({theta},{psi}) surface map for accurate 3-D modeling of a shot.

  10. Complete Surface Mapping of ICF Shells

    SciTech Connect

    Stephens, R.B.; Olson, D.; Huang, H.; Gibson, J.B.

    2004-03-15

    Inertial confinement fusion shells have previously been evaluated on the basis of microscopic examination for local defects and limited surface profiling to represent their average fluctuation power. Since defects are local, and don't always have visible edges, this approach both misses some important fluctuations and doesn't properly represent the spatially dependent surface fluctuation power. We have taken the first step toward correcting this problem by demonstrating the capability to completely map the surface of a NIF shell with the resolution to account for all modes. This allows complete accounting of all the surface fluctuations. In the future this capability could be used for valuable shells to generate a complete r({theta}, {phi}) surface map for accurate 3-D modeling of a shot.

  11. Spectrophotometry of the shell around AG Carinae

    NASA Technical Reports Server (NTRS)

    Mitra, P. Mila; Dufour, Reginald J.

    1990-01-01

    Spatially-resolved long-slit spectrophotometry are presented for two regions of the shell nebula around the P-Cygni variable star AG Carinae. The spectra cover the 3700-6800 A wavelength range. Emission-line diagnostics are used to derive extinction, electron temperatures, and densities for various positions in the nebula. The chemical abundances and ionization structure are calculated and compared with other types of planetary nebulae and shells around other luminous stars. It is found that the N/O and N/S ratios of Ag Car are high compared to solar neighborhood ISM values. The O/H depletion found for the AG Car shell approaches that found in the condensations of the Eta Car system.

  12. Modeling of microencapsulated polymer shell solidification

    SciTech Connect

    Boone, T.; Cheung, L.; Nelson, D.; Soane, D.; Wilemski, G.; Cook, R.

    1995-03-08

    A finite element transport model has been developed and implemented to complement experimental efforts to improve the quality of ICF target shells produced via controlled-mass microencapsulation. The model provides an efficient means to explore the effect of processing variables on the dynamics of shell dimensions, concentricity, and phase behavior. Comparisons with experiments showed that the model successfully predicts the evolution of wall thinning and core/wall density differences. The model was used to efficiently explore and identify initial wall compositions and processing temperatures which resulted in concentricity improvements from 65 to 99%. The evolution of trace amounts of water entering into the shell wall was also tracked in the simulations. Comparisons with phase envelope estimations from modified UNIFAP calculations suggest that the water content trajectory approaches the two-phase region where vacuole formation via microphase separation may occur.

  13. Spline Approximation of Thin Shell Dynamics

    NASA Technical Reports Server (NTRS)

    delRosario, R. C. H.; Smith, R. C.

    1996-01-01

    A spline-based method for approximating thin shell dynamics is presented here. While the method is developed in the context of the Donnell-Mushtari thin shell equations, it can be easily extended to the Byrne-Flugge-Lur'ye equations or other models for shells of revolution as warranted by applications. The primary requirements for the method include accuracy, flexibility and efficiency in smart material applications. To accomplish this, the method was designed to be flexible with regard to boundary conditions, material nonhomogeneities due to sensors and actuators, and inputs from smart material actuators such as piezoceramic patches. The accuracy of the method was also of primary concern, both to guarantee full resolution of structural dynamics and to facilitate the development of PDE-based controllers which ultimately require real-time implementation. Several numerical examples provide initial evidence demonstrating the efficacy of the method.

  14. Adaptive piezoelectric shell structures: theory and experiments

    NASA Astrophysics Data System (ADS)

    Tzou, H. S.; Zhong, J. P.

    1993-07-01

    Active "smart" space and mechanical structures with adaptive dynamic characteristics have long been interested in a variety of high-performance systems, e.g. flexible space structures, flexible robots, "smart" machines etc. In this paper, an active adaptive structure made of piezoelectric materials is proposed and evaluated. Electromechanical equations of motion and generalised boundary conditions of a generic piezoelectric shell subjected to mechanical and electrical excitations are derived using Hamilton's principle and the linear piezoelectric theory. The structural adaptivity is achieved by a voltage feedback (open or closed loops) utilising the converse piezoelectric effect. Applications of the theory is demonstrated in a bimorph beam case and a cylindrical shell case. Frequency manipulation of the bimorph beam is studied theoretically and experimentally. Damping control of the cylindrical shell via in-plane membrane forces is also investigated.

  15. Material transport across Europa's ice shell

    NASA Astrophysics Data System (ADS)

    Allu Peddinti, Divya; McNamara, Allen K.

    2015-06-01

    Jupiter's moon Europa exhibits a deformed icy surface with salt deposits concentrated along the varied geological features. The topographic alignment of salt deposits has been speculated to indicate an endogenic sourcing of the material. Two-way transport of salts from a liquid-water ocean beneath the ice shell to the surface, and vice versa, has been speculated. We present dynamical models that demonstrate the incorporation of newly frozen ice into convective plumes within the ice shell, caused by convection within the ice shell that drives dynamic topography along the ice-ocean boundary. The new ice that forms at the freezing front can be transported by the rising ice plumes toward the surface until it is blocked by a high-viscosity lid at the surface. Weakening of the lid by tidal or tectonic forces could then lead to the surface detection of ocean trace chemistry captured in the newly formed ice.

  16. DECam Observations of the Tidal Shells Around NGC 3923

    NASA Astrophysics Data System (ADS)

    Miller, Bryan; Grooms, Connor; Puzia, Thomas H.; Matthew, Taylor; Graeme, Candlish; McGaugh, Stacy S.; Mihos, Chris; Smith, Rory; Schirmer, Mischa

    2016-01-01

    Stellar shells around elliptical galaxies are thought to be the results of near-radial mergers with low mass companions. Thus, the shell systems contain information about the merger history and gravitational potential of the elliptical galaxy. We present a preliminary census of the shell system of NGC 3923 from extremely deep g and i-band DECam imaging. NGC 3923 has the largest know shell system, with different studies finding between 27 and 42 shells. We present an overview of the DECam data reduction and an initial analysis of the shell system.

  17. Inner shell radial pin geometry and mounting arrangement

    DOEpatents

    Leach, David; Bergendahl, Peter Allen

    2002-01-01

    Circumferentially spaced arrays of support pins are disposed through access openings in an outer turbine shell and have projections received in recesses in forward and aft sections of an inner turbine shell supported from the outer shell. The projections have arcuate sides in a circumferential direction affording line contacts with the side walls of the recesses and are spaced from end faces of the recesses, enabling radial and axial expansion and contraction of the inner shell relative to the outer shell. All loads are taken up in a tangential direction by the outer shell with the support pins taking no radial loadings.

  18. Exciton dynamics in GaAs/(Al,Ga)As core-shell nanowires with shell quantum dots

    NASA Astrophysics Data System (ADS)

    Corfdir, Pierre; Küpers, Hanno; Lewis, Ryan B.; Flissikowski, Timur; Grahn, Holger T.; Geelhaar, Lutz; Brandt, Oliver

    2016-10-01

    We study the dynamics of excitons in GaAs/(Al,Ga)As core-shell nanowires by continuous-wave and time-resolved photoluminescence and photoluminescence excitation spectroscopy. Strong Al segregation in the shell of the nanowires leads to the formation of Ga-rich inclusions acting as quantum dots. At 10 K, intense light emission associated with these shell quantum dots is observed. The average radiative lifetime of excitons confined in the shell quantum dots is 1.7 ns. We show that excitons may tunnel toward adjacent shell quantum dots and nonradiative point defects. We investigate the changes in the dynamics of charge carriers in the shell with increasing temperature, with particular emphasis on the transfer of carriers from the shell to the core of the nanowires. We finally discuss the implications of carrier localization in the (Al,Ga)As shell for fundamental studies and optoelectronic applications based on core-shell III-As nanowires.

  19. Advances in Shell Buckling: Theory and Experiments

    NASA Astrophysics Data System (ADS)

    Thompson, J. Michael T.

    In a recent feature article in this journal, coauthored by Gert van der Heijden, I described the static-dynamic analogy and its role in understanding the localized post-buckling of shell-like structures, looking exclusively at integrable systems. We showed the true significance of the Maxwell energy criterion load in predicting the sudden onset of "shock sensitivity" to lateral disturbances. The present paper extends the survey to cover nonintegrable systems, such as thin compressed shells. These exhibit spatial chaos, generating a multiplicity of localized paths (and escape routes) with complex snaking and laddering phenomena. The final theoretical contribution shows how these concepts relate to the response and energy barriers of an axially compressed cylindrical shell. After surveying NASA's current shell-testing programme, a new nondestructive technique is proposed to estimate the "shock sensitivity" of a laboratory specimen that is in a compressed metastable state before buckling. A probe is used to measure the nonlinear load-deflection characteristic under a rigidly applied lateral displacement. Sensing the passive resisting force, it can be plotted in real time against the displacement, displaying an equilibrium path along which the force rises to a maximum and then decreases to zero: having reached the free state of the shell that forms a mountain-pass in the potential energy. The area under this graph gives the energy barrier against lateral shocks. The test is repeated at different levels of the overall compression. If a symmetry-breaking bifurcation is encountered on the path, computer simulations show how this can be suppressed by a controlled secondary probe tuned to deliver zero force on the shell.

  20. Tuning the synthesis of platinum-copper nanoparticles with a hollow core and porous shell for the selective hydrogenation of furfural to furfuryl alcohol

    NASA Astrophysics Data System (ADS)

    Huang, Shuangshuang; Yang, Nating; Wang, Shibin; Sun, Yuhan; Zhu, Yan

    2016-07-01

    Pt-Cu nanoparticles constructed with a hollow core and porous shell have been synthesized in which Pt-Cu cages with multiporous outermost shells are formed at the initial stage and then the Pt and Cu atoms in solution continuously fed these hollow-core of cages by passing through the porous tunnels of the outermost shells, finally leading to the formation of hollow structures with different sizes. Furthermore, these hollow-core Pt-Cu nanoparticles are more effective than the solid-core Pt-Cu nanoparticles for the catalytic hydrogenation of furfural toward furfuryl alcohol. The former can achieve almost 100% conversion of furfural with 100% selectivity toward the alcohol.Pt-Cu nanoparticles constructed with a hollow core and porous shell have been synthesized in which Pt-Cu cages with multiporous outermost shells are formed at the initial stage and then the Pt and Cu atoms in solution continuously fed these hollow-core of cages by passing through the porous tunnels of the outermost shells, finally leading to the formation of hollow structures with different sizes. Furthermore, these hollow-core Pt-Cu nanoparticles are more effective than the solid-core Pt-Cu nanoparticles for the catalytic hydrogenation of furfural toward furfuryl alcohol. The former can achieve almost 100% conversion of furfural with 100% selectivity toward the alcohol. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr03894h

  1. Static spherically symmetric thin shell wormhole colliding with a spherical thin shell

    NASA Astrophysics Data System (ADS)

    Wang, Xiaobao; Gao, Sijie

    2016-03-01

    We consider a static spherically symmetric thin shell wormhole that collides with another thin shell consisting of ordinary matter. By employing the geometrical constraint, which leads to the conservation of energy and momentum, we show that the state after the collision can be solved from the initial data. In the low speed approximation, the solutions are rather simple. The shell may either bounce back or pass through the wormhole. In either case, the wormhole shrinks right after the collision. In the "bouncing" case, a surprising result is that the radial speeds before and after the collision satisfy an addition law, which is independent of other parameters of the wormhole and the shell. Once the shell passes through the wormhole, we find that the shell always expands. However, the expansion rate is the same as its collapsing rate right before the collision. Finally, we find the solution for the shell moving together with the wormhole. This work sheds light on the interaction between wormholes and matter.

  2. What's in a Shell? - Interactions of Chemistry and Structure at Submicron Levels in Bivalve Shells

    NASA Astrophysics Data System (ADS)

    Jacob, D. E.; Piazolo, S.; Trimby, P.

    2014-12-01

    The wide geographical distribution of bivalve shells makes them much favoured paleoclimate proxy archives. However, they are amongst the materials most affected by physiological effects, making the correct deciphering of these archives a challenging task. Shell building plans are usually hierarchic, thus optimizing mechanical properties. However, different structures common to certain bivalve families, such as the prism-nacre or the crossed-lamellar structures, are assembled from very different building blocks. These structural differences coincide with chemical and crystallographic differences suggesting critically different formation mechanisms within the bivalve class. Most importantly some bivalves form their shells from amorphous calcium carbonate that crystallizes in situ once assembled into the shell. We present new correlated multi-scale structural and compositional data for different shell bivalve shell structures such as nacre-prism, cross-lamellar intermediate structures. Data are obtained using EBSD, FIB-assisted TEM and Transmission Kikuchi Diffraction combined with Nano-SIMS and Raman Microspectrometry and suggest that formation from amorphous phases is widespread and results in different calcium carbonate polymorphs to be present in the shell with distinct chemical compositions. The results highlight the complex nature of the biomaterials, which has consequences for the precision and accuracy of paleotemperature calculations.

  3. Stability analysis of dynamic thin shells

    NASA Astrophysics Data System (ADS)

    Lobo, Francisco S. N.; Crawford, Paulo

    2005-11-01

    We analyse the stability of generic spherically symmetric thin shells to linearized perturbations around static solutions. We include the momentum flux term in the conservation identity, deduced from the 'ADM' constraint and the Lanczos equations. Following the Ishak Lake analysis, we deduce a master equation which dictates the stable equilibrium configurations. Considering the transparency condition, we study the stability of thin shells around black holes, showing that our analysis is in agreement with previous results. Applying the analysis to traversable wormhole geometries, by considering specific choices for the form function, we deduce stability regions and find that the latter may be significantly increased by considering appropriate choices for the redshift function.

  4. On the elastic stability of shells

    NASA Technical Reports Server (NTRS)

    Horton, W. H.

    1976-01-01

    A synopsis of a series of investigations into the instability of axially compressed cylindrical shells is given. The objective of the research, which was made with models, was to devise a technique of nondestructive evaluation. The results show that, with models at any rate, success was achieved. Probing methods which can be used to determine the locations of weakness and the pertinent instability load levels were devised. The research on large scale shells was undertaken to determine the critical loads under as uniform a circumferential distribution of axial compressive force as possible. It is clear from the results presented that this objective was met.

  5. Off-shell kinematics in nuclear processes

    NASA Astrophysics Data System (ADS)

    Thakur, Jagannath

    1983-11-01

    A semirelativistic model based on an approximate solution of the Bethe-Salpeter equation used previously to construct a conserved electromagnetic current with arbitrary interaction is generalized to arbitrary processes and extended to many body targets. Although the technique appears valid and useful for introducing kinematic corrections in processes off few body targets, a paradoxical result emerges for large nuclei in that the relevant form factors, which must be evaluated far off-shell, can be dramatically different from that for free nucleons, contrary to the usual picture of the nucleus as composed of nearly free nucleons. NUCLEAR REACTIONS Bethe-Salpeter equation, off-shell kinematics, impulse approximation, paradox for large nuclei.

  6. Fast optimization of static axisymmetric shell structures

    NASA Astrophysics Data System (ADS)

    Jacoby, Jeffrey

    An axisymmetric shell optimization procedure is developed which is a fast, user-friendly and practical tool for design use in disciplines including aerospace, mechanical and civil engineering. The shape and thickness of a shell can be optimized to minimize shell mass, mass/volume ratio or stress with constraints imposed on von Mises stress and local buckling. The procedure was created with the aid of the GENOPT optimization development system (Dr. D. Bushnell, Lockheed Missiles and Space Co) and uses the FAST1 shell analysis program (Prof. C. R. Steele, Stanford University) to perform the constraint analysis. The optimization method used is the modified method of feasible directions. The procedure is fast because exact analysis methods allow complex shells to be modelled with only a few large shell elements and still retain a sufficiently accurate solution. This is of particular advantage near shell boundaries and intersections which can have small regions of very detailed variation in the solution. Finite element methods would require many small elements to capture accurately this detail with a resulting increase in computation time and model complexity. Reducing the complexity of the model also reduces the size of the required input and contributes to the simplicity of the procedure. Optimization design variables are the radial and axial coordinates of nodes and the shape parameters and thicknesses of the elements. Thickness distribution within an element can be optimized by specifying the thickness at evenly spaced control points. Spline interpolation is used to provide a smooth thickness variation between the control points. An effective method is developed for reducing the number of required stress constraint equations. Various shells have been optimized and include models for comparison with published results. Shape, thickness and shape/thickness optimization has been performed on examples including a simple aerobrake, sphere-nozzle intersections, ring

  7. Selective hypersensitivity to boiled razor shell.

    PubMed

    Martín-García, C; Carnés, J; Blanco, R; Martínez-Alonso, J C; Callejo-Melgosa, A; Frades, A; Colino, T

    2007-01-01

    Many types of seafood require cooking before ingestion and it has been demonstrated that this cooking process may affect the antigenicity and allergenicity of the food. We describe a case of anaphylaxis caused by selective sensitization to razor shell, a mollusc. In vivo and in vitro studies confirmed sensitization to boiled razor shell. Analysis of the nature of the allergen yielded results that were consistent with the findings of other authors and suggested that allergens involved in seafood allergy are commonly high molecular weight proteins that, in most cases, are heat stable.

  8. Low temperature solution-phase growth of ZnSe and ZnSe/CdSe core/shell nanowires.

    PubMed

    Petchsang, Nattasamon; Shapoval, Liubov; Vietmeyer, Felix; Yu, Yanghai; Hodak, Jose H; Tang, I-Ming; Kosel, Thomas H; Kuno, Masaru

    2011-08-01

    High quality ZnSe nanowires (NWs) and complementary ZnSe/CdSe core/shell species have been synthesized using a recently developed solution-liquid-solid (SLS) growth technique. In particular, bismuth salts as opposed to pre-synthesized Bi or Au/Bi nanoparticles have been used to grow NWs at low temperatures in solution. Resulting wires are characterized using transmission electron microscopy and possess mean ensemble diameters between 15 and 28 nm with accompanying lengths ranging from 4-10 μm. Subsequent solution-based overcoating chemistry results in ZnSe wires covered with CdSe nanocrystals. By varying the shell's growth time, different thicknesses can be obtained and range from 8 to 21 nm. More interestingly, the mean constituent CdSe nanocrystal diameter can be varied and results in size-dependent shell emission spectra.

  9. The development of shell-like distributions from newborn cometary ions

    NASA Technical Reports Server (NTRS)

    Gary, S. Peter; Hinata, Satoshi; Madland, Christian D.; Winske, Dan

    1986-01-01

    One-dimensional hybrid computer simulations that are spatially homogeneous are used to investigate the evolution of newborn cometary ions that interact self-consistently with the solar wind. Cometary ions injected at a constant rate are scattered by the growing electromagnetic fluctuations resulting from the associated free energy, and the scattering at relatively low fluctuating field amplitudes leads to shell-like velocity distributions which subtend about 4 pi in solid angle but which have small spread in speed. Shell-like distributions are found to occur when the ion injection rate is relatively slow, when the injected ion mass is relatively light, and when the energy density of the fluctuating magnetic fields exhibits linear growth.

  10. Experimental evaluation of drying characteristics of sewage sludge and hazelnut shell mixtures

    NASA Astrophysics Data System (ADS)

    Pehlivan, Hüseyin; Ateş, Asude; Özdemir, Mustafa

    2016-11-01

    In this study the drying behavior of organic and agricultural waste mixtures has been experimentally investigated. The usability of sewage sludge as an organic waste and hazelnut shell as an agricultural waste was assessed in different mixture range. The paper discusses the applicability of these mixtures as a recovery energy source. Moisture content of mixtures has been calculated in laboratory and plant conditions. Indoor and outdoor solar sludge drying plants were constructed in pilot scale for experimental purposes. Dry solids and climatic conditions were constantly measured. A total more than 140 samples including for drying has been carried out to build up results. Indoor and outdoor weather conditions are taken into consideration in winter and summer. The most effective drying capacity is obtained in mixture of 20 % hazelnut shell and 80 % sewage sludge.

  11. Femtosecond laser ablation of dielectric materials in the optical breakdown regime: Expansion of a transparent shell

    SciTech Connect

    Garcia-Lechuga, M.; Siegel, J. Hernandez-Rueda, J.; Solis, J.

    2014-09-15

    Phase transition pathways of matter upon ablation with ultrashort laser pulses have been considered to be understood long-since for metals and semiconductors. We provide evidence that also certain dielectrics follow the same pathway, even at high pulse energies triggering optical breakdown. Employing femtosecond microscopy, we observe a characteristic ring pattern within the ablating region that dynamically changes for increasing time delays between pump and probe pulse. These transient Newton rings are related to optical interference of the probe beam reflected at the front surface of the ablating layer with the reflection at the interface of the non-ablating substrate. Analysis of the ring structure shows that the ablation mechanism is initiated by a rarefaction wave leading within a few tens of picoseconds to the formation of a transparent thin shell of reduced density and refractive index, featuring optically sharp interfaces. The shell expands and eventually detaches from the solid material at delays of the order of 100 ps.

  12. Synthesis of Ge/Si core/shell nanowires with suppression of branch formation

    NASA Astrophysics Data System (ADS)

    Noguchi, Tomohiro; Simanullang, Marolop; Xu, Zhengyu; Usami, Koichi; Kodera, Tetsuo; Oda, Shunri

    2016-05-01

    Ge/Si core/shell nanowires (Ge/Si-NWs) are promising materials for applications such as transistors, sensors, and thermoelectric devices. A major problem in the synthesis of Ge/Si-NWs using Au catalysts in conjunction with vapor-liquid-solid chemical vapor deposition is the formation of branched Si nanowires on the surface of Ge nanowires because of the migration of Au nanoparticles that serve as seeds. Based on an analysis of the Au-Ge phase diagram, we propose a method to mitigate this issue. By introducing Ge-rich conditions during the temperature-increase step between the formation of the Ge core and the Si shell, we have successfully eliminated Au nanoparticles on Ge surfaces, and thus fabricated Ge/Si-NWs without Si nanowires.

  13. Femtosecond laser ablation of dielectric materials in the optical breakdown regime: Expansion of a transparent shell

    NASA Astrophysics Data System (ADS)

    Garcia-Lechuga, M.; Siegel, J.; Hernandez-Rueda, J.; Solis, J.

    2014-09-01

    Phase transition pathways of matter upon ablation with ultrashort laser pulses have been considered to be understood long-since for metals and semiconductors. We provide evidence that also certain dielectrics follow the same pathway, even at high pulse energies triggering optical breakdown. Employing femtosecond microscopy, we observe a characteristic ring pattern within the ablating region that dynamically changes for increasing time delays between pump and probe pulse. These transient Newton rings are related to optical interference of the probe beam reflected at the front surface of the ablating layer with the reflection at the interface of the non-ablating substrate. Analysis of the ring structure shows that the ablation mechanism is initiated by a rarefaction wave leading within a few tens of picoseconds to the formation of a transparent thin shell of reduced density and refractive index, featuring optically sharp interfaces. The shell expands and eventually detaches from the solid material at delays of the order of 100 ps.

  14. Characterizing inner-shell with spectral phase interferometry for direct electric-field reconstruction

    NASA Astrophysics Data System (ADS)

    Mashiko, Hiroki; Yamaguchi, Tomohiko; Oguri, Katsuya; Suda, Akira; Gotoh, Hideki

    2014-12-01

    In many atomic, molecular and solid systems, Lorentzian and Fano profiles are commonly observed in a broad research fields throughout a variety of spectroscopies. As the profile structure is related to the phase of the time-dependent dipole moment, it plays an important role in the study of quantum properties. Here we determine the dipole phase in the inner-shell transition using spectral phase interferometry for direct electric-field reconstruction (SPIDER) with isolated attosecond pulses (IAPs). In addition, we propose a scheme for pulse generation and compression by manipulating the inner-shell transition. The electromagnetic radiation generated by the transition is temporally compressed to a few femtoseconds in the extreme ultraviolet (XUV) region. The proposed pulse-compression scheme may provide an alternative route to producing attosecond pulses of light.

  15. Experimental evaluation of drying characteristics of sewage sludge and hazelnut shell mixtures

    NASA Astrophysics Data System (ADS)

    Pehlivan, Hüseyin; Ateş, Asude; Özdemir, Mustafa

    2016-01-01

    In this study the drying behavior of organic and agricultural waste mixtures has been experimentally investigated. The usability of sewage sludge as an organic waste and hazelnut shell as an agricultural waste was assessed in different mixture range. The paper discusses the applicability of these mixtures as a recovery energy source. Moisture content of mixtures has been calculated in laboratory and plant conditions. Indoor and outdoor solar sludge drying plants were constructed in pilot scale for experimental purposes. Dry solids and climatic conditions were constantly measured. A total more than 140 samples including for drying has been carried out to build up results. Indoor and outdoor weather conditions are taken into consideration in winter and summer. The most effective drying capacity is obtained in mixture of 20 % hazelnut shell and 80 % sewage sludge.

  16. Epoxy-acrylic core-shell particles by seeded emulsion polymerization.

    PubMed

    Chen, Liang; Hong, Liang; Lin, Jui-Ching; Meyers, Greg; Harris, Joseph; Radler, Michael

    2016-07-01

    We developed a novel method for synthesizing epoxy-acrylic hybrid latexes. We first prepared an aqueous dispersion of high molecular weight solid epoxy prepolymers using a mechanical dispersion process at elevated temperatures, and we subsequently used the epoxy dispersion as a seed in the emulsion polymerization of acrylic monomers comprising methyl methacrylate (MMA) and methacrylic acid (MAA). Advanced analytical techniques, such as scanning transmission X-ray microscopy (STXM) and peak force tapping atomic force microscopy (PFT-AFM), have elucidated a unique core-shell morphology of the epoxy-acrylic hybrid particles. Moreover, the formation of the core-shell morphology in the seeded emulsion polymerization process is primarily attributed to kinetic trapping of the acrylic phase at the exterior of the epoxy particles. By this new method, we are able to design the epoxy and acrylic polymers in two separate steps, and we can potentially synthesize epoxy-acrylic hybrid latexes with a broad range of compositions. PMID:27078740

  17. Self-assembled heterogeneous argon/neon core-shell clusters studied by photoelectron spectroscopy.

    PubMed

    Lundwall, M; Pokapanich, W; Bergersen, H; Lindblad, A; Rander, T; Ohrwall, G; Tchaplyguine, M; Barth, S; Hergenhahn, U; Svensson, S; Björneholm, O

    2007-06-01

    Clusters formed by a coexpansion process of argon and neon have been studied using synchrotron radiation. Electrons from interatomic Coulombic decay as well as ultraviolet and x-ray photoelectron spectroscopy were used to determine the heterogeneous nature of the clusters and the cluster structure. Binary clusters of argon and neon produced by coexpansion are shown to exhibit a core-shell structure placing argon in the core and neon in the outer shells. Furthermore, the authors show that 2 ML of neon on the argon core is sufficient for neon valence band formation resembling the neon solid. For 1 ML of neon the authors observe a bandwidth narrowing to about half of the bulk value.

  18. Epoxy-acrylic core-shell particles by seeded emulsion polymerization.

    PubMed

    Chen, Liang; Hong, Liang; Lin, Jui-Ching; Meyers, Greg; Harris, Joseph; Radler, Michael

    2016-07-01

    We developed a novel method for synthesizing epoxy-acrylic hybrid latexes. We first prepared an aqueous dispersion of high molecular weight solid epoxy prepolymers using a mechanical dispersion process at elevated temperatures, and we subsequently used the epoxy dispersion as a seed in the emulsion polymerization of acrylic monomers comprising methyl methacrylate (MMA) and methacrylic acid (MAA). Advanced analytical techniques, such as scanning transmission X-ray microscopy (STXM) and peak force tapping atomic force microscopy (PFT-AFM), have elucidated a unique core-shell morphology of the epoxy-acrylic hybrid particles. Moreover, the formation of the core-shell morphology in the seeded emulsion polymerization process is primarily attributed to kinetic trapping of the acrylic phase at the exterior of the epoxy particles. By this new method, we are able to design the epoxy and acrylic polymers in two separate steps, and we can potentially synthesize epoxy-acrylic hybrid latexes with a broad range of compositions.

  19. Cosmic Shell-Seekers Find a Beauty

    NASA Astrophysics Data System (ADS)

    2005-04-01

    Two scientists have discovered a distinctive shell of hot gas around the site of a distant supernova explosion by combining 150 hours of archived data collected by NASA's Chandra X-ray Observatory. This discovery is a significant step forward in solving a decades-old puzzle as to why some stellar explosions display shells and others do not. "The likely answer is that the explosion of every massive star sends a sonic boom rumbling through interstellar space," said Samar Safi-Harb of the University of Manitoba in Winnipeg, Canada, who is a coauthor with Heather Matheson on a paper describing the research that appears in the journal Advances in Space Research. "It's just that, some of the shells are harder to find than others because of the environment where the explosion occurs." The shell marks a sonic boom, or shock wave, generated by the supernova. Gas is heated to millions of degrees by the shock wave and produces X-rays, but little visible light. By examining the properties of the shell with an X-ray telescope, astronomers can work back to deduce the age (a few thousand years), and energy of the explosion, as well as information about the state of the star a million years before it exploded. Animation of a Supernova Explosion Animation of a Supernova Explosion It is likely that the star that produced the supernova remnant and shell was about 10 times as massive as the Sun. The absence of a detectable shell around this and similar supernova remnants had led astronomers to speculate that another, weaker type of explosion had occurred there. Now this hypothesis seems unlikely. Although many supernovas leave behind bright shells, others do not. This supernova remnant, identified as G21.5-0.9 by radio astronomers 30 years ago, was considered to be one that had no shell. A diffuse cloud of X-rays around the source was detected about 5 years ago by another group of astronomers and independently by Safi-Harb and colleagues using Chandra, but it took the careful

  20. A platonic solid templating Archimedean solid: an unprecedented nanometre-sized Ag37 cluster

    NASA Astrophysics Data System (ADS)

    Li, Xiao-Yu; Su, Hai-Feng; Yu, Kai; Tan, Yuan-Zhi; Wang, Xing-Po; Zhao, Ya-Qin; Sun, Di; Zheng, Lan-Sun

    2015-04-01

    The spontaneous formation of discrete spherical nanosized molecules is prevalent in nature, but the authentic structural mimicry of such highly symmetric polyhedra from edge sharing of regular polygons has remained elusive. Here we present a novel ball-shaped {(HNEt3)[Ag37S4(SC6H4tBu)24(CF3COO)6(H2O)12]} cluster (1) that is assembled via a one-pot process from polymeric {(HNEt3)2[Ag10(SC6H4tBu)12]}n and CF3COOAg. Single crystal X-ray analysis confirmed that 1 is a Td symmetric spherical molecule with a [Ag36(SC6H4tBu)24] anion shell enwrapping a AgS4 tetrahedron. The shell topology of 1 belongs to one of 13 Archimedean solids, a truncated tetrahedron with four edge-shared hexagons and trigons, which are supported by a AgS4 Platonic solid in the core. Interestingly, the cluster emits green luminescence centered at 515 nm at room temperature. Our investigations have provided a promising synthetic protocol for a high-nuclearity silver cluster based on underlying geometrical principles.The spontaneous formation of discrete spherical nanosized molecules is prevalent in nature, but the authentic structural mimicry of such highly symmetric polyhedra from edge sharing of regular polygons has remained elusive. Here we present a novel ball-shaped {(HNEt3)[Ag37S4(SC6H4tBu)24(CF3COO)6(H2O)12]} cluster (1) that is assembled via a one-pot process from polymeric {(HNEt3)2[Ag10(SC6H4tBu)12]}n and CF3COOAg. Single crystal X-ray analysis confirmed that 1 is a Td symmetric spherical molecule with a [Ag36(SC6H4tBu)24] anion shell enwrapping a AgS4 tetrahedron. The shell topology of 1 belongs to one of 13 Archimedean solids, a truncated tetrahedron with four edge-shared hexagons and trigons, which are supported by a AgS4 Platonic solid in the core. Interestingly, the cluster emits green luminescence centered at 515 nm at room temperature. Our investigations have provided a promising synthetic protocol for a high-nuclearity silver cluster based on underlying geometrical principles

  1. Low temperature solution-phase growth of ZnSe and ZnSe/CdSe core/shell nanowires

    NASA Astrophysics Data System (ADS)

    Petchsang, Nattasamon; Shapoval, Liubov; Vietmeyer, Felix; Yu, Yanghai; Hodak, Jose H.; Tang, I.-Ming; Kosel, Thomas H.; Kuno, Masaru

    2011-08-01

    High quality ZnSe nanowires (NWs) and complementary ZnSe/CdSe core/shell species have been synthesized using a recently developed solution-liquid-solid (SLS) growth technique. In particular, bismuth salts as opposed to pre-synthesized Bi or Au/Bi nanoparticles have been used to grow NWs at low temperatures in solution. Resulting wires are characterized using transmission electron microscopy and possess mean ensemble diameters between 15 and 28 nm with accompanying lengths ranging from 4-10 μm. Subsequent solution-based overcoating chemistry results in ZnSe wires covered with CdSe nanocrystals. By varying the shell's growth time, different thicknesses can be obtained and range from 8 to 21 nm. More interestingly, the mean constituent CdSe nanocrystal diameter can be varied and results in size-dependent shell emission spectra.High quality ZnSe nanowires (NWs) and complementary ZnSe/CdSe core/shell species have been synthesized using a recently developed solution-liquid-solid (SLS) growth technique. In particular, bismuth salts as opposed to pre-synthesized Bi or Au/Bi nanoparticles have been used to grow NWs at low temperatures in solution. Resulting wires are characterized using transmission electron microscopy and possess mean ensemble diameters between 15 and 28 nm with accompanying lengths ranging from 4-10 μm. Subsequent solution-based overcoating chemistry results in ZnSe wires covered with CdSe nanocrystals. By varying the shell's growth time, different thicknesses can be obtained and range from 8 to 21 nm. More interestingly, the mean constituent CdSe nanocrystal diameter can be varied and results in size-dependent shell emission spectra. Electronic supplementary information (ESI) available. See DOI: 10.1039/c1nr10176e

  2. A Facile Synthesis of SiO2@Co/mSiO2 Egg-Shell Nanoreactors for Fischer-Tropsch Reaction.

    PubMed

    Kwon, Jae In; Kim, Tae Wan; Park, Ji Chan; Yang, Jung-Il; Lee, Kwan Young

    2016-02-01

    Recently, a convenient melt-infiltration method, using a hydrated metal salt with porous support, was developed to prepare various metal/metal-oxide nanocatalysts. Until now, millimeter-scale, bead-shaped, cobalt egg-shell catalysts have been used to enhance the rate of reactant diffusion and catalyst performance. In the present work, new SiO2@Co/mSiO2 egg-shell nanoreactors (~300 nm) were synthesized with controlled Co content of 10 and 20 wt%. This was accomplished using a selective melt-infiltration process with porous silica shells around solid-silica cores. The SiO2@Co(10 wt%)/mSiO2 egg-shell catalyst that bears small cobalt nanoparticles of -2 nm was successfully employed for the industrially valuable Fischer-Tropsch synthesis reaction, showing the high activity of -8.0 x 10(-5) mol(CO) x gCo(-1) x S(-1).

  3. Synthesis, characterization and evaluation of uniformly sized core-shell imprinted microspheres for the separation trans-resveratrol from giant knotweed

    NASA Astrophysics Data System (ADS)

    Zhang, Zhaohui; Liu, Li; Li, Hui; Yao, Shouzhuo

    2009-09-01

    A novel core-shell molecularly imprinting microspheres (MIMs) with trans-resveratrol as the template molecule; acrylamide (AA) as functional monomer and ethylene glycol dimethacrylate (EGDMA) as cross-linker, was prepared based on SiO 2 microspheres with surface imprinting technique. These core-shell trans-resveratrol imprinted microspheres were characterized by infrared spectra (IR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and high performance liquid chromatography (HPLC). The results showed that these core-shell imprinted microspheres, which take on perfect spherical shape with average shell thickness of 150 nm, exhibit especially selective recognition for trans-resveratrol. These imprinted microspheres were applied as solid-phase extraction materials for selective extraction of trans-resveratrol from giant knotweed extracting solution successfully.

  4. 50 CFR 648.50 - Shell-height standard.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...). Shell height is a straight line measurement from the hinge to the part of the shell that is farthest away from the hinge. (b) Compliance and sampling. Any time at landing or after, including when...

  5. MOND implications for spectral line profiles of shell galaxies: shell formation history and mass-velocity scaling relations

    NASA Astrophysics Data System (ADS)

    Bílek, M.; Jungwiert, B.; Ebrová, I.; Bartošková, K.

    2015-03-01

    Context. Many ellipticals are surrounded by round stellar shells probably stemming from minor mergers. A new method for constraining gravitational potential in elliptical galaxies has recently been suggested. It uses the spectral line profiles of these shells to measure the circular velocity at the edge of the shell and the expansion velocity of the shell itself. MOND is an alternative to the dark matter framework aiming to solve the missing mass problem. Aims: We study how the circular and expansion velocities behave in MOND for large shells. Methods: The asymptotic behavior for infinitely large shells is derived analytically. The applicability of the asymptotic results for finitely sized shells is studied numerically on a grid of galaxies modeled with Sérsic spheres. Results: Circular velocity settles asymptotically at a value determined by the baryonic mass of the galaxy forming the baryonic Tully-Fisher relation known for disk galaxies. Shell expansion velocity also becomes asymptotically constant. The expansion velocities of large shells form a multibranched analogy to the baryonic Tully-Fisher relation, together with the galactic baryonic masses. For many - but not all - shell galaxies, the asymptotic values of these two types of velocities are reached under the effective radius. If MOND is assumed to work in ellipticals, then the shell spectra allow many details of the history to be revealed about the formation of the shell system, including its age. The results pertaining to circular velocities apply to all elliptical galaxies, not only those with shells.

  6. Morphology-controlled synthesis of Ti{sup 3+} self-doped yolk–shell structure titanium oxide with superior photocatalytic activity under visible light

    SciTech Connect

    Wang, Shixiong; Yang, Xiangjun; Wang, Yapeng; Liu, Lixiang; Guo, Yuanyuan; Guo, Hong

    2014-05-01

    Ti{sup 3+} self-doped yolk–shell structure titanium oxide nanoparticle aggregates are fabricated through an environmental template-free route and the reduction reaction at low temperature subsequently. After the Ti{sup 3+} doping, the reduced TiO{sub 2} sample exhibits a wide visible-light absorption ranged from 400 nm to 800 nm. The intrinsic hollow core–shell microstructure can make multiple reflections of light within the chamber, and thus results in more efficient use of the light source compared with solid structure. Besides, the large surface area can render the sample with a high activity. Therefore, Ti{sup 3+} self-doped yolk–shell structure titanium oxide exhibits a superior photocatalytic activity under visible light. This strategy is simple, cheap and mass-productive, which may shed light on a new avenue for large scale production of self-doped yolk–shell structural nano functional materials for catalyst, sensors, energy storage and other new applications. - Graphical abstract: A facile generic strategy is employed to prepare Ti{sup 3+} self-doped yolk–shell structure titanium oxide nanoparticle aggregates with the superior photocatalytic activity under visible light. - Highlights: • Yolk–shell TiO{sub 2} mesospheres are synthesized by solvothermal alcoholysis. • Ti{sup 3+} self-doped yolk–shell structure titanium oxide is obtained at low temperature. • It exhibits a remarkable photocatalytic activity.

  7. DNA nanoparticles with core-shell morphology.

    PubMed

    Chandran, Preethi L; Dimitriadis, Emilios K; Lisziewicz, Julianna; Speransky, Vlad; Horkay, Ferenc

    2014-10-14

    Mannobiose-modified polyethylenimines (PEI) are used in gene therapy to generate nanoparticles of DNA that can be targeted to the antigen-presenting cells of the immune system. We report that the sugar modification alters the DNA organization within the nanoparticles from homogenous to shell-like packing. The depth-dependent packing of DNA within the nanoparticles was probed using AFM nano-indentation. Unmodified PEI-DNA nanoparticles display linear elastic properties and depth-independent mechanics, characteristic of homogenous materials. Mannobiose-modified nanoparticles, however, showed distinct force regimes that were dependent on indentation depth, with 'buckling'-like response that is reproducible and not due to particle failure. By comparison with theoretical studies of spherical shell mechanics, the structure of mannobiosylated particles was deduced to be a thin shell with wall thickness in the order of few nanometers, and a fluid-filled core. The shell-core structure is also consistent with observations of nanoparticle denting in altered solution conditions, with measurements of nanoparticle water content from AFM images, and with images of DNA distribution in Transmission Electron Microscopy.

  8. Calculation of tubular joints as compound shells

    NASA Astrophysics Data System (ADS)

    Golovanov, A. I.

    A scheme for joining isoparametric finite shell elements with a bend in the middle surface is described. A solution is presented for the problem of the stress-strain state of a T-joint loaded by internal pressure. A refined scheme is proposed for calculating structures of this kind with allowance for the stiffness of the welded joint.

  9. 7 CFR 996.19 - Shelled peanuts.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 8 2011-01-01 2011-01-01 false Shelled peanuts. 996.19 Section 996.19 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE MINIMUM QUALITY AND HANDLING STANDARDS FOR DOMESTIC AND IMPORTED PEANUTS MARKETED IN THE UNITED STATES Definitions § 996.19...

  10. 7 CFR 996.19 - Shelled peanuts.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Shelled peanuts. 996.19 Section 996.19 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE MINIMUM QUALITY AND HANDLING STANDARDS FOR DOMESTIC AND IMPORTED PEANUTS MARKETED IN THE UNITED STATES Definitions § 996.19...

  11. On Newton’s shell theorem

    NASA Astrophysics Data System (ADS)

    Borghi, Riccardo

    2014-03-01

    In the present letter, Newton’s theorem for the gravitational field outside a uniform spherical shell is considered. In particular, a purely geometric proof of proposition LXXI/theorem XXXI of Newton’s Principia, which is suitable for undergraduates and even skilled high-school students, is proposed. Minimal knowledge of elementary calculus and three-dimensional Euclidean geometry are required.

  12. Palaeontology: pterosaur egg with a leathery shell.

    PubMed

    Ji, Qiang; Ji, Shu-An; Cheng, Yen-Nien; You, Hai-Lu; Lü, Jun-Chang; Liu, Yong-Qing; Yuan, Chong-Xi

    2004-12-01

    The recent discovery of a pterosaur egg with embryonic skeleton and soft tissues from the Yixian Formation confirmed that the flying pterosaurs were oviparous. Here we describe another pterosaur egg whose exquisite preservation indicates that the shell structure was soft and leathery.

  13. On-Shell Methods in Perturbative QCD

    SciTech Connect

    Bern, Zvi; Dixon, Lance J.; Kosower, David A.

    2007-04-25

    We review on-shell methods for computing multi-parton scattering amplitudes in perturbative QCD, utilizing their unitarity and factorization properties. We focus on aspects which are useful for the construction of one-loop amplitudes needed for phenomenological studies at the Large Hadron Collider.

  14. Double-shell tank emergency pumping guide

    SciTech Connect

    BROWN, M.H.

    1999-02-24

    This Double-Shell Tank Emergency Pumping Guide provides the preplanning necessary to expeditiously remove any waste that may leak from the primary tank to the secondary tank for Hanford's 28 DSTS. The strategy is described, applicable emergency procedures are referenced, and transfer routes and pumping equipment for each tank are identified.

  15. Double-shell tank emergency pumping guide

    SciTech Connect

    BROWN, M.H.

    1999-05-18

    This Double-Shell Tank Emergency Pumping Guide provides the preplanning necessary to expeditiously remove any waste that may leak from the primary tank to the secondary tank for Hanfords 28 DSTs. The strategy is described, applicable emergency procedures are referenced, and transfer routes and pumping equipment for each tank are identified.

  16. New method for calculating shell correction

    SciTech Connect

    Salamon, P.; Kruppa, A. T.; Vertse, T.

    2010-06-15

    A new method is presented for the calculation of the shell correction with the inclusion of the continuum part of the spectrum. The smoothing function used has a finite energy range in contrast to the Gaussian shape of the Strutinski method. The new method is especially useful for light nuclei where the generalized Strutinski procedure cannot be applied.

  17. BOWOOSS: bionic optimized wood shells with sustainability

    NASA Astrophysics Data System (ADS)

    Pohl, Göran

    2011-04-01

    In architecture, shell construction is used for the most efficient, large spatial structures. Until now the use of wood rather played a marginal role, implementing those examples of architecture, although this material offers manifold advantages, especially against the background of accelerating shortage of resources and increasing requirements concerning the energy balance. Regarding the implementation of shells, nature offers a wide range of suggestions. The focus of the examinations is on the shells of marine plankton, especially of diatoms, whose richness in species promises the discovery of entirely new construction principles. The project is targeting at transferring advantageous features of these organisms on industrial produced, modular wood shell structures. Currently a transfer of these structures in CAD - models is taking place, helping to perform stress analysis by computational methods. Micro as well as macro structures are the subject of diverse consideration, allowing to draw the necessary conclusions for an architectural design. The insights of these tests are the basis for the development of physical models on different scales, which are used to verify the different approaches. Another important aim which is promoted in the project is to enhance the competitiveness of timber construction. Downsizing of the prefabricated structural elements leads to considerable lower transportation costs as abnormal loads can be avoided as far as possible and means of transportation can be loaded with higher efficiency so that an important contribution to the sustainability in the field of architecture can also be made.

  18. Helium-Shell Nucleosynthesis and Extinct Radioactivities

    NASA Astrophysics Data System (ADS)

    Meyer, B. S.; The, L.-S.; Clayton, D. D.; El Eid, M. F.

    2004-03-01

    We present details of explosive nucleosynthesis in the helium-burning shell of a 25 solar mass star. We describe the production of short-lived radioactivities in this environment. We finally describe how to access the details of our calculations over the world-wide web.

  19. On the Theory of Thin Shallow Shells

    NASA Technical Reports Server (NTRS)

    Nazarov, A. A.

    1956-01-01

    This report is concerned with the theory of thin shallow shells. It does not employ the lines of curvature as the coordinate system, but employs "almost cartesian coordinates" or the coordinates obtained by cutting the surface into two mutually orthogonal systems of parallel planes.

  20. Polarimetry of nacre in iridescent shells

    NASA Astrophysics Data System (ADS)

    Metzler, R. A.; Burgess, C.; Regan, B.; Spano, S.; Galvez, E. J.

    2014-09-01

    We investigate the light transmitted or reflected from nacre (mother of pearl) taken from the iridescent shell of the bivalve Pinctad a fucata. These nacre surfaces have a rich structure, composed of aragonite crystals arranged as tablets or bricks, 5 μm wide and 400-500 nm thick, surrounded by 30nm thick organic mortar. The light reflected from these shell surfaces, or transmitted through thin polished layers, is rich in its polarization content, exhibiting a space dependent variation in the state of polarization with a high density of polarization singularities. Our goal is to use the polarization information to infer the structure of the biominerals and the role of the organic layer in determining the orientation of the crystals. In the experiments we send the light from a laser with a uniform state of polarization onto the shell, and analyze the light that is either transmitted or reflected, depending on the type of experiment, imaging it after its passage through polarization filters. We use the images from distinct filters to obtain the Stokes parameters, and hence the state of polarization, of each image point. We also construct the Mueller matrix for each imaged point, via 36 measurements. We do this for distinct physical and chemical treatments of the shell sample. Preliminary data shows that the organic layer may be responsible for organizing a multi-crystalline arrangement of aragonite tablets.

  1. Sanitation in the Shell Egg Processing Environment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hazard analysis and critical control programs (HACCP) will eventually be required for commercial shell egg processing plants. Sanitation is an essential prerequisite program for HACCP and is based upon current Good Manufacturing Practices (cGMPs) as listed in the Code of Federal Regulations. Good ...

  2. Torrefaction of pomaces and nut shells

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Technical: Apple, grape, olive, and tomato pomaces as well as almond and walnut shells were torrefied at different temperatures and times in a muffle furnace. The fiber content and thermal stability of the raw byproducts were examined using fiber analysis and thermogravimetric analysis (TGA), respec...

  3. Measuring Shell Resonances of Spherical Acoustic Resonators

    NASA Astrophysics Data System (ADS)

    Truong, D.; Sparasci, F.; Foltête, E.; Ouisse, M.; Pitre, L.

    2011-01-01

    Coupling between the gas and shell is a concern in the experiment used at LNE-CNAM to determine the Boltzmann constant k B by an acoustic method. As the walls of real resonators are not perfectly rigid, some perturbations occur in the frequency range of the acoustic resonances measured within helium gas contained in the cavity. As a contribution for a better understanding of this phenomenon, an experiment to measure the shell modes of the spherical resonators is in use in this laboratory. A work in progress to assess these modes using a hammer blow method together with modal analysis is reported here. The study is carried out with an air-filled, copper-walled, half-liter quasi-spherical resonator in the frequency range from 1 Hz to 20 kHz. Results show that the shell modes expand into multiple resonances of similar modal shape, including the "breathing" mode. The observations reported in other studies of shell perturbations at other frequencies than the breathing frequency are confirmed.

  4. Method to produce large, uniform hollow spherical shells

    DOEpatents

    Hendricks, Charles D.

    1985-01-01

    Large, uniform hollow spherical shells are produced by forming uniform size drops of heat decomposable or vaporizable material, evaporating the drops to form dried particles, coating the dried particles with a layer of shell forming material, and heating the composite particles to melt the outer layer and decompose or vaporize the inner particle to form an expanding inner gas bubble which expands the outer layer. By cycling the temperature and pressure on the hollow shells, spherical shells with uniform walls are produced.

  5. Interior remodeling of the shell by a gastropod mollusc

    PubMed Central

    Kohn, Alan J.; Myers, Elizabeth R.; Meenakshi, V. R.

    1979-01-01

    As the Conus shell grows by spiraling of the outer lip around the axis, profound internal shell dissolution thins the walls of the protected penultimate whorl from several millimeters to <50μm. Shell material is added to the inside of the spire and the anterior part of the columella. The resulting shell has a uniformly thick last whorl and thickened spire that enhance defense against crushing predators and a greatly expanded interior living space for the animal. Images PMID:16592680

  6. Characterization of Russian ballistic furnace shells, February, 1999, batch

    SciTech Connect

    Fearon, E

    1999-04-02

    This report documents the characterization of the latest batch of shells produced in the Ballistic Furnace System at the Lebedev Physical Institute, Moscow, Russia, that we received in mid-February, 1999. The batch consisted of three cassettes containing 36 shells in each cassette. An initial sphericity measurement was done, each shell was weighed, and shells were selected that were spherical enough to run on the Sphere Mapper AFM.

  7. Doping GaP Core-Shell Nanowire pn-Junctions: A Study by Off-Axis Electron Holography.

    PubMed

    Yazdi, Sadegh; Berg, Alexander; Borgström, Magnus T; Kasama, Takeshi; Beleggia, Marco; Samuelson, Lars; Wagner, Jakob B

    2015-06-10

    The doping process in GaP core-shell nanowire pn-junctions using different precursors is evaluated by mapping the nanowires' electrostatic potential distribution by means of off-axis electron holography. Three precursors, triethyltin (TESn), ditertiarybutylselenide, and silane are investigated for n-type doping of nanowire shells; among them, TESn is shown to be the most efficient precursor. Off-axis electron holography reveals higher electrostatic potentials in the regions of nanowire cores grown by the vapor-liquid-solid (VLS) mechanism (axial growth) than the regions grown parasitically by the vapor-solid (VS) mechanism (radial growth), attributed to different incorporation efficiency between VLS and VS of unintentional p-type carbon doping originating from the trimethylgallium precursor. This study shows that off-axis electron holography of doped nanowires is unique in terms of the ability to map the electrostatic potential and thereby the active dopant distribution with high spatial resolution.

  8. Measurement and calculation of L-shell transitions in M-shell iron ions

    NASA Astrophysics Data System (ADS)

    Beiersdorfer, P.; Lepson, J. K.; Díaz, F.; Ishikawa, Y.; Träbert, E.

    2013-09-01

    We have made high-resolution measurements of the iron L-shell emission near 15 Å using the EBIT-I electron beam ion trap at Livermore that exhibit L-shell transitions from autoionizing levels in Fe13+, Fe14+ and Fe15+ ions. The observed L-shell iron spectra were modeled using the flexible atomic code augmented with transition energies produced by calculations based on the relativistic multi-reference Møller-Plesset (MRMP) perturbation theory, allowing us to identify multiple M-shell iron lines. Our measured values for the Fe XV emission lines are in excellent agreement with a recent measurement using the BESSY-II synchrotron but the present measurements have somewhat higher accuracy. Our MRMP calculations are compared to earlier calculations using the many-body perturbation theory approach, and we find good agreement for some but not all transitions.

  9. Laser cooling of solids

    SciTech Connect

    Epstein, Richard I; Sheik-bahae, Mansoor

    2008-01-01

    We present an overview of solid-state optical refrigeration also known as laser cooling in solids by fluorescence upconversion. The idea of cooling a solid-state optical material by simply shining a laser beam onto it may sound counter intuitive but is rapidly becoming a promising technology for future cryocooler. We chart the evolution of this science in rare-earth doped solids and semiconductors.

  10. ROTARY BULK SOLIDS DIVIDER

    DOEpatents

    Maronde, Carl P.; Killmeyer JR., Richard P.

    1992-03-03

    An apparatus for the disbursement of a bulk solid sample comprising, a gravity hopper having a top open end and a bottom discharge end, a feeder positioned beneath the gravity hopper so as to receive a bulk solid sample flowing from the bottom discharge end, and a conveyor receiving the bulk solid sample from the feeder and rotating on an axis that allows the bulk solid sample to disperse the sample to a collection station.

  11. Rotary bulk solids divider

    DOEpatents

    Maronde, Carl P.; Killmeyer, Jr., Richard P.

    1992-01-01

    An apparatus for the disbursement of a bulk solid sample comprising, a gravity hopper having a top open end and a bottom discharge end, a feeder positioned beneath the gravity hopper so as to receive a bulk solid sample flowing from the bottom discharge end, and a conveyor receiving the bulk solid sample from the feeder and rotating on an axis that allows the bulk solid sample to disperse the sample to a collection station.

  12. Tetraphenylborate Solids Stability Tests

    SciTech Connect

    Walker, D.D.

    1997-06-25

    Tetraphenylborate solids are a potentially large source of benzene in the slurries produced in the In-Tank Precipitation (ITP) process. The stability of the solids is an important consideration in the safety analysis of the process and we desire an understanding of the factors that influence the rate of conversion of the solids to benzene. This report discusses current testing of the stability of tetraphenylborate solids.

  13. Polymer-encapsulated carbon capture liquids that tolerate precipitation of solids for increased capacity

    DOEpatents

    Aines, Roger D; Bourcier, William L; Spadaccini, Christopher M; Stolaroff, Joshuah K

    2015-02-03

    A system for carbon dioxide capture from flue gas and other industrial gas sources utilizes microcapsules with very thin polymer shells. The contents of the microcapsules can be liquids or mixtures of liquids and solids. The microcapsules are exposed to the flue gas and other industrial gas and take up carbon dioxide from the flue gas and other industrial gas and eventual precipitate solids in the capsule.

  14. Defects in liquid crystal nematic shells

    NASA Astrophysics Data System (ADS)

    Fernandez-Nieves, A.; Utada, A. S.; Vitelli, V.; Link, D. R.; Nelson, D. R.; Weitz, D. A.

    2006-03-01

    We generate water/liquid crystal (LC)/water double emulsions via recent micro-capillary fluidic devices [A. S. Utada, et.al. Science 308, 537 (2005)]. The resultant objects are stabilized against coalescence by using surfactants or adequate polymers; these also fix the boundary conditions for the director field n. We use 4-pentyl-4-cyanobiphenyl (5CB) and impose tangential boundary conditions at both water/LC interfaces by having polyvinyl alcohol (PVA) dispersed in the inner and outer water phases. We confirm recent predictions [D. R. Nelson, NanoLetters 2, 1125 (2002)] and find that four strength s=+1/2 defects are present; this is in contrast to the two s=+1 defect bipolar configuration observed for bulk spheres [A. Fernandez-Nieves, et.al. Phys. Rev. Lett. 92, 105503 (2004)]. However, these defects do not lie in the vertices of a tetrahedron but are pushed towards each other until certain equilibration distance is reached. In addition to the four defect shells, we observe shells with two s=+1 defects and even with three defects, a s=+1 and two s=+1/2. We argue these configurations arise from nematic bulk distortions that become important as the shell thickness increases. Finally, by adding a different surfactant, sodium dodecyl sulphate (SDS), to the outer phase, we can change the director boundary conditions at the outermost interface from parallel to homeotropic, to induce coalescing of the two pair of defects in the four defect shell configuration to yield two defect bipolar shells.

  15. Searching for nova shells around cataclysmic variables

    NASA Astrophysics Data System (ADS)

    Sahman, D. I.; Dhillon, V. S.; Knigge, C.; Marsh, T. R.

    2015-08-01

    We present the results of a search for nova shells around 101 cataclysmic variables (CVs), using H α images taken with the 4.2-m William Herschel Telescope (WHT) and the 2.5-m Isaac Newton Telescope Photometric H α Survey of the Northern Galactic Plane (IPHAS). Both telescopes are located on La Palma. We concentrated our WHT search on nova-like variables, whilst our IPHAS search covered all CVs in the IPHAS footprint. We found one shell out of the 24 nova-like variables we examined. The newly discovered shell is around V1315 Aql and has a radius of ˜2.5 arcmin, indicative of a nova eruption approximately 120 yr ago. This result is consistent with the idea that the high mass-transfer rate exhibited by nova-like variables is due to enhanced irradiation of the secondary by the hot white dwarf following a recent nova eruption. The implications of our observations for the lifetime of the nova-like variable phase are discussed. We also examined four asynchronous polars, but found no new shells around any of them, so we are unable to confirm that a recent nova eruption is the cause of the asynchronicity in the white dwarf spin. We find tentative evidence of a faint shell around the dwarf nova V1363 Cyg. In addition, we find evidence for a light echo around the nova V2275 Cyg, which erupted in 2001, indicative of an earlier nova eruption ˜300 yr ago, making V2275 Cyg a possible recurrent nova.

  16. SHELL - PRESSURE VOLUME PROPERTIES OF METALLIC BELLOWS

    NASA Technical Reports Server (NTRS)

    Kiefling, L.

    1994-01-01

    A majority of the liquid-fueled rocket vehicles developed in the past have been plagued by an instability known as POGO. The POGO phenomenon involves dynamics of the vehicle structure, dynamics of the propellant in the feedline, and the engine dynamic transfer function. Each of these three items must be accurately known in order to determine stability. Metallic bellows are commonly used as segments of propellant feedlines for rocket-propelled vehicles to accommodate temperature-induced length variations, manufacturing tolerances, and gimbaling of the engines. These bellows sections deform radially and change volume when internal pressure varies, and the magnitude of such deformation is much higher than that for the straight, cylindrical segments of the line. The greater flexibility of the bellows decreases the frequency of acoustic oscillations in the line. Calculating elastic stiffness is difficult due to the radial deformation of a bellows section. SHELL was developed specifically to calculate changes in volume of a bellows due to changes in internal pressure. Input to the program consists of tables describing the material, the geometry of the convolutions and loading. The output gives displacements and volume change that can be used for POGO or waterhammer analysis. SHELL is written in standard FORTRAN 77. This program was originally developed on a Univac 1100 series computer and has been successfully implemented on IBM 370 series computers running MVS and DEC VAX series computers running VMS. The main memory requirement for running SHELL under VMS is 116K. The program source code, IBM JCL for compiling and running SHELL, and sample input are provided with the program. SHELL is available on a 9-track 1600 BPI ASCII CARD IMAGE magnetic tape. This program was developed in 1989. IBM is a trademark of International Business Machines Corporation. DEC, VAX and VMS are registered trademarks of Digital Equipment Corporation. Univac 1100 is a trademark of Unisys

  17. Tetraphenylborate Solids Stability Tests

    SciTech Connect

    Walker, D.D.; Edwards, T.B.

    1997-12-19

    Tetraphenylborate solids provide a potentially large source of benzene in the slurries produced in the In-Tank Precipitation process. The stability of the solids is an important consideration in the safety analysis of the process and we desire an understanding of the factors that influence the rate of conversion of the solids to benzene.

  18. Thermal dryers for solids

    SciTech Connect

    Billings, C.H.

    1993-12-01

    This article describes an indirect thermal dryer added to dewater solids before incineration of sewage sludge at a Buffalo, New York waste water treatment plant. In the first three months of operation, the solids inventory was reduced from about 799 tons to 250 tons. The solids processed in the plant's multiple hearth incinerators varied from 12 to 14 tons per hour.

  19. Solid State Division

    SciTech Connect

    Green, P.H.; Watson, D.M.

    1989-08-01

    This report contains brief discussions on work done in the Solid State Division of Oak Ridge National Laboratory. The topics covered are: Theoretical Solid State Physics; Neutron scattering; Physical properties of materials; The synthesis and characterization of materials; Ion beam and laser processing; and Structure of solids and surfaces. (LSP)

  20. Improved solid aerosol generator

    DOEpatents

    Prescott, D.S.; Schober, R.K.; Beller, J.

    1988-07-19

    An improved solid aerosol generator used to produce a gas borne stream of dry, solid particles of predetermined size and concentration. The improved solid aerosol generator nebulizes a feed solution of known concentration with a flow of preheated gas and dries the resultant wet heated aerosol in a grounded, conical heating chamber, achieving high recovery and flow rates. 2 figs.

  1. Solid aerosol generator

    DOEpatents

    Prescott, Donald S.; Schober, Robert K.; Beller, John

    1992-01-01

    An improved solid aerosol generator used to produce a gas borne stream of dry, solid particles of predetermined size and concentration. The improved solid aerosol generator nebulizes a feed solution of known concentration with a flow of preheated gas and dries the resultant wet heated aerosol in a grounded, conical heating chamber, achieving high recovery and flow rates.

  2. Solid aerosol generator

    DOEpatents

    Prescott, D.S.; Schober, R.K.; Beller, J.

    1992-03-17

    An improved solid aerosol generator used to produce a gas borne stream of dry, solid particles of predetermined size and concentration is disclosed. The improved solid aerosol generator nebulizes a feed solution of known concentration with a flow of preheated gas and dries the resultant wet heated aerosol in a grounded, conical heating chamber, achieving high recovery and flow rates. 2 figs.

  3. Simulating the co-encapsulation of drugs in a "smart" core-shell-shell polymer nanoparticle.

    PubMed

    Buxton, Gavin A

    2014-03-01

    A coarse-grained lattice Monte Carlo method is used to simulate co-encapsulation and delivery of both a hydrophilic and hydrophobic drug from polymer nanoparticles. In particular, core-shell-shell polymer nanoparticles with acid-labile bonds are simulated, and the preferential release of the encapsulated drugs near more acidic tumors is captured. While these simple models lack the molecular details of a real system, they can reveal interesting insights concerning the effects of entropy and enthalpy in these systems.

  4. Imperfection sensitivity of pressured buckling of biopolymer spherical shells

    NASA Astrophysics Data System (ADS)

    Zhang, Lei; Ru, C. Q.

    2016-06-01

    Imperfection sensitivity is essential for mechanical behavior of biopolymer shells [such as ultrasound contrast agents (UCAs) and spherical viruses] characterized by high geometric heterogeneity. In this work, an imperfection sensitivity analysis is conducted based on a refined shell model recently developed for spherical biopolymer shells of high structural heterogeneity and thickness nonuniformity. The influence of related parameters (including the ratio of radius to average shell thickness, the ratio of transverse shear modulus to in-plane shear modulus, and the ratio of effective bending thickness to average shell thickness) on imperfection sensitivity is examined for pressured buckling. Our results show that the ratio of effective bending thickness to average shell thickness has a major effect on the imperfection sensitivity, while the effect of the ratio of transverse shear modulus to in-plane shear modulus is usually negligible. For example, with physically realistic parameters for typical imperfect spherical biopolymer shells, the present model predicts that actual maximum external pressure could be reduced to as low as 60% of that of a perfect UCA spherical shell or 55%-65% of that of a perfect spherical virus shell, respectively. The moderate imperfection sensitivity of spherical biopolymer shells with physically realistic imperfection is largely attributed to the fact that biopolymer shells are relatively thicker (defined by smaller radius-to-thickness ratio) and therefore practically realistic imperfection amplitude normalized by thickness is very small as compared to that of classical elastic thin shells which have much larger radius-to-thickness ratio.

  5. Leathery Hull Peanuts – Effect on Shelling Performance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    When shelling peanuts from the 2012 peanut crop, various shellers experienced diminished shelling plant throughput when shelling peanuts harvested from isolated geographical regions. Shellers reported a reduction of 25-30% throughput of the first stage sheller bank with significant increases in spli...

  6. Porous Core-Shell Nanostructures for Catalytic Applications

    NASA Astrophysics Data System (ADS)

    Ewers, Trevor David

    Porous core-shell nanostructures have recently received much attention for their enhanced thermal stability. They show great potential in the field of catalysis, as reactant gases can diffuse in and out of the porous shell while the core particle is protected from sintering, a process in which particles coalesce to form larger particles. Sintering is a large problem in industry and is the primary cause of irreversible deactivation. Despite the obvious advantages of high thermal stability, porous core-shell nanoparticles can be developed to have additional interactive properties from the combination of the core and shell together, rather than just the core particle alone. This dissertation focuses on developing new porous core-shell systems in which both the core and shell take part in catalysis. Two types of systems are explored; (1) yolk-shell nanostructures with reducible oxide shells formed using the Kirkendall effect and (2) ceramic-based porous oxide shells formed using sol-gel chemistry. Of the Kirkendall-based systems, Au FexOy and Cu CoO were synthesized and studied for catalytic applications. Additionally, ZnO was explored as a potential shelling material. Sol-gel work focused on optimizing synthetic methods to allow for coating of small gold particles, which remains a challenge today. Mixed metal oxides were explored as a shelling material to make dual catalysts in which the product of a reaction on the core particle becomes a reactant within the shell.

  7. Shells. Modified Primary. Revised. Anchorage School District Elementary Science Program.

    ERIC Educational Resources Information Center

    Defendorf, Jean, Ed.

    This publication provides information and activities for teaching about seashells and process skills including observing, classifying, collecting and interpreting data, inferring, measuring, and predicting. There are 10 lessons. Lessons 1 through 5 deal with an introduction to shells, why animals have shells, observing and classifying shells, the…

  8. 46 CFR 174.225 - Hull penetrations and shell connections.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Hull penetrations and shell connections. 174.225 Section 174.225 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY... § 174.225 Hull penetrations and shell connections. Each overboard discharge and shell connection...

  9. Mollusc evolution: seven shells on the sea shore.

    PubMed

    Telford, Maximilian J

    2013-11-01

    Recent phylogenies unite two seemingly very different groups of mollusc: the Polyplacophora with multiple shells and the shell-less Aplacophora. The finding of seven muscle rows in larvae of both classes suggests that polyplacophoran-like shell rows have been lost in adult Aplacophora.

  10. 41 CFR 102-85.120 - What is shell Rent?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 41 Public Contracts and Property Management 3 2013-07-01 2013-07-01 false What is shell Rent? 102-85.120 Section 102-85.120 Public Contracts and Property Management Federal Property Management... GSA SPACE Rent Charges § 102-85.120 What is shell Rent? Shell Rent is that portion of GSA Rent...

  11. 41 CFR 102-85.120 - What is shell Rent?

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 41 Public Contracts and Property Management 3 2012-01-01 2012-01-01 false What is shell Rent? 102-85.120 Section 102-85.120 Public Contracts and Property Management Federal Property Management... GSA SPACE Rent Charges § 102-85.120 What is shell Rent? Shell Rent is that portion of GSA Rent...

  12. 41 CFR 102-85.120 - What is shell Rent?

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 41 Public Contracts and Property Management 3 2011-01-01 2011-01-01 false What is shell Rent? 102-85.120 Section 102-85.120 Public Contracts and Property Management Federal Property Management... GSA SPACE Rent Charges § 102-85.120 What is shell Rent? Shell Rent is that portion of GSA Rent...

  13. 41 CFR 102-85.120 - What is shell Rent?

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 41 Public Contracts and Property Management 3 2014-01-01 2014-01-01 false What is shell Rent? 102-85.120 Section 102-85.120 Public Contracts and Property Management Federal Property Management... GSA SPACE Rent Charges § 102-85.120 What is shell Rent? Shell Rent is that portion of GSA Rent...

  14. Mollusc evolution: seven shells on the sea shore.

    PubMed

    Telford, Maximilian J

    2013-11-01

    Recent phylogenies unite two seemingly very different groups of mollusc: the Polyplacophora with multiple shells and the shell-less Aplacophora. The finding of seven muscle rows in larvae of both classes suggests that polyplacophoran-like shell rows have been lost in adult Aplacophora. PMID:24200320

  15. Pseudo-Symmetry and Majorana Operators in pf-Shell

    SciTech Connect

    Valencia, J. P.; Wu, H. C.

    2007-10-26

    The Majorana operator of the pseudo ds-shell preserves the SU-tilde(4) symmetry, and in a unified manner it reproduces reasonably well the ground state energies of the nine nuclei in this shell. The study of {beta} decay in the same shell provides further support for the SU-tilde(4) symmetry.

  16. Palladium-platinum core-shell electrocatalysts for oxygen reduction reaction prepared with the assistance of citric acid

    DOE PAGES

    Zhang, Lulu; Su, Dong; Zhu, Shangqian; Chang, Qiaowan; Yue, Jeffrey; Du, Zheng; Shao, Minhua

    2016-04-26

    Core–shell structure is a promising alternative to solid platinum (Pt) nanoparticles as electrocatalyst for oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs). A simple method of preparing palladium (Pd)–platinum (Pt) core–shell catalysts (Pd@Pt/C) in a gram-batch was developed with the assistance of citric acid. The Pt shell deposition involves three different pathways: galvanic displacement reaction between Pd atoms and Pt cations, chemical reduction by citric acid, and reduction by negative charges on Pd surfaces. The uniform ultrathin (~0.4 nm) Pt shell was characterized by in situ X-ray diffraction (XRD) and high-angle annular dark-field scanning transmission electron microscopymore » (HAADF-STEM) images combined with electron energy loss spectroscopy (EELS). Compared with state-of-the-art Pt/C, the Pd@Pt/C core–shell catalyst showed 4 times higher Pt mass activity and much better durability upon potential cycling. As a result, both the mass activity and durability were comparable to that of Pd@Pt/C synthesized by a Cu-mediated-Pt-displacement method, which is more complicated and difficult for mass production.« less

  17. GaAs nanowires with oxidation-proof arsenic capping for the growth of an epitaxial shell.

    PubMed

    Guan, X; Becdelievre, J; Benali, A; Botella, C; Grenet, G; Regreny, P; Chauvin, N; Blanchard, N P; Jaurand, X; Saint-Girons, G; Bachelet, R; Gendry, M; Penuelas, J

    2016-08-25

    We propose an arsenic-capping/decapping method, allowing the growth of an epitaxial shell around the GaAs nanowire (NW) core which is exposed to an ambient atmosphere, and without the introduction of impurities. Self-catalyzed GaAs NW arrays were firstly grown on Si(111) substrates by solid-source molecular beam epitaxy. Aiming for protecting the active surface of the GaAs NW core, the arsenic-capping/decapping method has been applied. To validate the effect of this method, different core/shell NWs have been fabricated. Analyses highlight the benefit of the As capping-decapping method for further epitaxial shell growth: an epitaxial shell with a smooth surface is achieved in the case of As-capped-decapped GaAs NWs, comparable to the in situ grown GaAs/AlGaAs NWs. This As capping method opens a way for the epitaxial growth of heterogeneous material shells such as functional oxides using different reactors. PMID:27513669

  18. Enhanced Conductivity in CZTS/Cu(2-x)Se Nanocrystal Thin Films: Growth of a Conductive Shell.

    PubMed

    Korala, Lasantha; McGoffin, J Tyler; Prieto, Amy L

    2016-02-01

    Poor charge transport in Cu2ZnSnS4 (CZTS) nanocrystal (NC) thin films presents a great challenge in the fabrication of solar cells without postannealing treatments. We introduce a novel approach to facilitate the charge carrier hopping between CZTS NCs by growing a stoichiometric Cu2Se shell that can be oxidized to form a conductive Cu2-xSe phase when exposed to air. The CZTS/Cu2Se core/shell NCs with varying numbers of shell monolayers were synthesized by the successive ionic layer adsorption and reaction (SILAR) method, and the variation in structural and optical properties of the CZTS NCs with varying shell thicknesses was investigated. Solid-phase sulfide ligand exchange was employed to fabricate NC thin films by layer-by-layer dip coating and a 2 orders of magnitude rise in dark conductivity (∼10(-3) S cm(-1) at 0 monolayer and ∼10(-1) S cm(-1) at 1.5 monolayers) was observed with an increase in the number of shell monolayers. The approach described herein is the first key step in achieving a significant increase in the photoconductivity of as-deposited CZTS NC thin films. PMID:26745286

  19. Microporous activated carbons prepared from palm shell by thermal activation and their application to sulfur dioxide adsorption.

    PubMed

    Guo, Jia; Lua, Aik Chong

    2002-07-15

    Textural characterization of activated carbons prepared from palm shell by thermal activation with carbon dioxide (CO(2)) gas is reported in this paper. Palm shell (endocarp) is an abundant agricultural solid waste from palm-oil processing mills in many tropical countries such as Malaysia, Indonesia, and Thailand. The effects of activation temperature on the textural properties of the palm-shell activated carbons, namely specific surface area (BET method), porosity, and microporosity, were investigated. The activated carbons prepared from palm shell possessed well-developed porosity, predominantly microporosity, leading to potential applications in gas-phase adsorption for air pollution control. Static and dynamic adsorption tests for sulfur dioxide (SO(2)), a common gaseous pollutant, were carried out in a thermogravimetric analyzer and a packed column configuration respectively. The effects of adsorption temperature, adsorbate inlet concentration, and adsorbate superficial velocity on the adsorptive performance of the prepared activated carbons were studied. The palm-shell activated carbon was found to have substantial capability for the adsorption of SO(2), comparable to those of some commercial products and an adsorbent derived from another biomass.

  20. Acoustic scattering from an infinitely long cylindrical shell with an internal mass attached by multiple axisymmetrically distributed stiffeners

    NASA Astrophysics Data System (ADS)

    Titovich, Alexey S.; Norris, Andrew N.

    2015-03-01

    A thin infinitely long elastic shell is stiffened by J in number identical lengthwise ribs distributed uniformly around the circumference and joined to a rod in the center. The 2D model of the substructure is a rigid central mass supported by J axisymmetrically placed linear springs. The response of the shell-spring-mass system is quite different from a fluid filled shell or that of a solid cylinder due to the discrete number of contact points which couple the displacement of the shell at different locations. Exterior acoustic scattering due to normal plane wave incidence is solved in closed form for arbitrary J. The scattering matrix associated with the normal mode solution displays a simple structure, composed of distinct sub-matrices which decouple the incident and scattered fields into J families. The presence of a spring-mass substructure causes resonances which are shown to be related to the subsonic shell flexural waves, and an approximate analytic expression is derived for the quasi-flexural resonance frequencies. Numerical simulations indicate that the new solution for J ≥ 3 springs results in a complicated scattering response for plane wave incidence. As the number of springs becomes large enough, the total scattering cross-section is asymptotically zero at low frequencies and slightly increased compared to the empty shell at moderate frequencies due to the added stiffness and mass. It is also observed that the sensitivity to the angle of incidence diminishes as the number of springs is increased. This system can be tuned by selecting the shell thickness, spring stiffness and added mass to yield desired quasi-static effective properties making it a candidate element for graded index sonic crystals.