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Sample records for prolate spheroidal shell

  1. Coulomb energy of uniformly charged spheroidal shell systems.

    Science.gov (United States)

    Jadhao, Vikram; Yao, Zhenwei; Thomas, Creighton K; de la Cruz, Monica Olvera

    2015-03-01

    We provide exact expressions for the electrostatic energy of uniformly charged prolate and oblate spheroidal shells. We find that uniformly charged prolate spheroids of eccentricity greater than 0.9 have lower Coulomb energy than a sphere of the same area. For the volume-constrained case, we find that a sphere has the highest Coulomb energy among all spheroidal shells. Further, we derive the change in the Coulomb energy of a uniformly charged shell due to small, area-conserving perturbations on the spherical shape. Our perturbation calculations show that buckling-type deformations on a sphere can lower the Coulomb energy. Finally, we consider the possibility of counterion condensation on the spheroidal shell surface. We employ a Manning-Oosawa two-state model approximation to evaluate the renormalized charge and analyze the behavior of the equilibrium free energy as a function of the shell's aspect ratio for both area-constrained and volume-constrained cases. Counterion condensation is seen to favor the formation of spheroidal structures over a sphere of equal area for high values of shell volume fractions.

  2. Effect of Cu Salt Molarity on the Nanostructure of CuO Prolate Spheroid

    Science.gov (United States)

    Sabeeh, Sabah H.; Hussein, Hashim Abed; Judran, Hadia Kadhim

    Copper sulfate pentahydrate was used as a source of Cu ion with five different molarities (0.02, 0.05, 0.1, 0.15, 2 and 0.25M). XRD, FE-SEM and TEM techniques all showed that CuO samples have polycrystalline monoclinic structure. CuO prolate spheroid is assembled from nanoparticles as building units. It was demonstrated that the purity, morphology, size range of prolate spheroid and density of nano building units are significantly influenced by Cu precursor’s molarity. The pure phase of CuO prolate spheroid was produced via molarity of 0.2M with crystallite size of 15.1565nm while the particle size of building units ranges from 16nm to 21nm. The stability of CuO nanosuspension or nanofluid was evaluated by zeta potential analysis. The obtained properties of specific structure with large surface area of CuO prolate spheroid make it a promising candidate for wide range of potential applications as in nanofluids for cooling purposes.

  3. Generalized prolate spheroidal wave functions for optical finite fractional Fourier and linear canonical transforms.

    Science.gov (United States)

    Pei, Soo-Chang; Ding, Jian-Jiun

    2005-03-01

    Prolate spheroidal wave functions (PSWFs) are known to be useful for analyzing the properties of the finite-extension Fourier transform (fi-FT). We extend the theory of PSWFs for the finite-extension fractional Fourier transform, the finite-extension linear canonical transform, and the finite-extension offset linear canonical transform. These finite transforms are more flexible than the fi-FT and can model much more generalized optical systems. We also illustrate how to use the generalized prolate spheroidal functions we derive to analyze the energy-preservation ratio, the self-imaging phenomenon, and the resonance phenomenon of the finite-sized one-stage or multiple-stage optical systems.

  4. Hydrogen atom and the H+2 and HeH++ molecular ions inside prolate spheroidal boxes

    International Nuclear Information System (INIS)

    Ley-Koo, E.; Cruz, S.A.

    1981-01-01

    We formulate the exact solution of the Schroedinger equation for systems of one electron in the Coulomb field of one or two fixed nuclei at the foci inside prolate spheroidal boxes. Numerical results are obtained for the energy eigenvalues and eigenfunctions of the lowest states of the hydrogen atom and the H + 2 and HeH ++ molecular ions for boxes of different sizes and eccentricities. We also evaluate the hyperfine splitting of atomic hydrogen and of H + 2

  5. Two-dimensional particle-in-cell plasma source ion implantation of a prolate spheroid target

    International Nuclear Information System (INIS)

    Cheng-Sen, Liu; Hong-Ying, Han; Xiao-Qing, Peng; Ye, Chang; De-Zhen, Wang

    2010-01-01

    A two-dimensional particle-in-cell simulation is used to study the time-dependent evolution of the sheath surrounding a prolate spheroid target during a high voltage pulse in plasma source ion implantation. Our study shows that the potential contour lines pack more closely in the plasma sheath near the vertex of the major axis, i.e. where a thinner sheath is formed, and a non-uniform total ion dose distribution is incident along the surface of the prolate spheroid target due to the focusing of ions by the potential structure. Ion focusing takes place not only at the vertex of the major axis, where dense potential contour lines exist, but also at the vertex of the minor axis, where sparse contour lines exist. This results in two peaks of the received ion dose, locating at the vertices of the major and minor axes of the prolate spheroid target, and an ion dose valley, staying always between the vertices, rather than at the vertex of the minor axis

  6. Two-dimensional particle-in-cell plasma source ion implantation of a prolate spheroid target

    Science.gov (United States)

    Liu, Cheng-Sen; Han, Hong-Ying; Peng, Xiao-Qing; Chang, Ye; Wang, De-Zhen

    2010-03-01

    A two-dimensional particle-in-cell simulation is used to study the time-dependent evolution of the sheath surrounding a prolate spheroid target during a high voltage pulse in plasma source ion implantation. Our study shows that the potential contour lines pack more closely in the plasma sheath near the vertex of the major axis, i.e. where a thinner sheath is formed, and a non-uniform total ion dose distribution is incident along the surface of the prolate spheroid target due to the focusing of ions by the potential structure. Ion focusing takes place not only at the vertex of the major axis, where dense potential contour lines exist, but also at the vertex of the minor axis, where sparse contour lines exist. This results in two peaks of the received ion dose, locating at the vertices of the major and minor axes of the prolate spheroid target, and an ion dose valley, staying always between the vertices, rather than at the vertex of the minor axis.

  7. Fully-resolved prolate spheroids in turbulent channel flows: A lattice Boltzmann study

    Science.gov (United States)

    Eshghinejadfard, Amir; Hosseini, Seyed Ali; Thévenin, Dominique

    2017-09-01

    Particles are present in many natural and industrial multiphase flows. In most practical cases, particle shape is not spherical, leading to additional difficulties for numerical studies. In this paper, DNS of turbulent channel flows with finite-size prolate spheroids is performed. The geometry includes a straight wall-bounded channel at a frictional Reynolds number of 180 seeded with particles. Three different particle shapes are considered, either spheroidal (aspect ratio λ =2 or 4) or spherical (λ =1 ). Solid-phase volume fraction has been varied between 0.75% and 1.5%. Lattice Boltzmann method (LBM) is used to model the fluid flow. The influence of the particles on the flow field is simulated by immersed boundary method (IBM). In this Eulerian-Lagrangian framework, the trajectory of each particle is computed individually. All particle-particle and particle-fluid interactions are considered (four-way coupling). Results show that, in the range of examined volume fractions, mean fluid velocity is reduced by addition of particles. However, velocity reduction by spheroids is much lower than that by spheres; 2% and 1.6%, compared to 4.6%. Maximum streamwise velocity fluctuations are reduced by addition of particle. By comparing particle and fluid velocities, it is seen that spheroids move faster than the fluid before reaching the same speed in the channel center. Spheres, on the other hand, move slower than the fluid in the buffer layer. Close to the wall, all particle types move faster than the fluid. Moreover, prolate spheroids show a preferential orientation in the streamwise direction, which is stronger close to the wall. Far from the wall, the orientation of spheroidal particles tends to isotropy.

  8. Fully-resolved prolate spheroids in turbulent channel flows: A lattice Boltzmann study

    Directory of Open Access Journals (Sweden)

    Amir Eshghinejadfard

    2017-09-01

    Full Text Available Particles are present in many natural and industrial multiphase flows. In most practical cases, particle shape is not spherical, leading to additional difficulties for numerical studies. In this paper, DNS of turbulent channel flows with finite-size prolate spheroids is performed. The geometry includes a straight wall-bounded channel at a frictional Reynolds number of 180 seeded with particles. Three different particle shapes are considered, either spheroidal (aspect ratio λ=2 or 4 or spherical (λ=1. Solid-phase volume fraction has been varied between 0.75% and 1.5%. Lattice Boltzmann method (LBM is used to model the fluid flow. The influence of the particles on the flow field is simulated by immersed boundary method (IBM. In this Eulerian-Lagrangian framework, the trajectory of each particle is computed individually. All particle-particle and particle-fluid interactions are considered (four-way coupling. Results show that, in the range of examined volume fractions, mean fluid velocity is reduced by addition of particles. However, velocity reduction by spheroids is much lower than that by spheres; 2% and 1.6%, compared to 4.6%. Maximum streamwise velocity fluctuations are reduced by addition of particle. By comparing particle and fluid velocities, it is seen that spheroids move faster than the fluid before reaching the same speed in the channel center. Spheres, on the other hand, move slower than the fluid in the buffer layer. Close to the wall, all particle types move faster than the fluid. Moreover, prolate spheroids show a preferential orientation in the streamwise direction, which is stronger close to the wall. Far from the wall, the orientation of spheroidal particles tends to isotropy.

  9. Prolate spheroidal hematite particles equatorially belt with drug-carrying layered double hydroxide disks: Ring Nebula-like nanocomposites

    Directory of Open Access Journals (Sweden)

    Nedim Ay Ahmet

    2011-01-01

    Full Text Available Abstract A new nanocomposite architecture is reported which combines prolate spheroidal hematite nanoparticles with drug-carrying layered double hydroxide [LDH] disks in a single structure. Spindle-shaped hematite nanoparticles with average length of 225 nm and width of 75 nm were obtained by thermal decomposition of hydrothermally synthesized hematite. The particles were first coated with Mg-Al-NO3-LDH shell and then subjected to anion exchange with salicylate ions. The resulting bio-nanohybrid displayed a close structural resemblance to that of the Ring Nebula. Scanning electron microscope and transmission electron microscopy images showed that the LDH disks are stacked around the equatorial part of the ellipsoid extending along the main axis. This geometry possesses great structural tunability as the composition of the LDH and the nature of the interlayer region can be tailored and lead to novel applications in areas ranging from functional materials to medicine by encapsulating various guest molecules.

  10. Prolate spheroidal hematite particles equatorially belt with drug-carrying layered double hydroxide disks: Ring Nebula-like nanocomposites.

    Science.gov (United States)

    Nedim Ay, Ahmet; Konuk, Deniz; Zümreoglu-Karan, Birgul

    2011-02-03

    A new nanocomposite architecture is reported which combines prolate spheroidal hematite nanoparticles with drug-carrying layered double hydroxide [LDH] disks in a single structure. Spindle-shaped hematite nanoparticles with average length of 225 nm and width of 75 nm were obtained by thermal decomposition of hydrothermally synthesized hematite. The particles were first coated with Mg-Al-NO3-LDH shell and then subjected to anion exchange with salicylate ions. The resulting bio-nanohybrid displayed a close structural resemblance to that of the Ring Nebula. Scanning electron microscope and transmission electron microscopy images showed that the LDH disks are stacked around the equatorial part of the ellipsoid extending along the main axis. This geometry possesses great structural tunability as the composition of the LDH and the nature of the interlayer region can be tailored and lead to novel applications in areas ranging from functional materials to medicine by encapsulating various guest molecules.

  11. Theoretical investigation of resonance frequencies in long wavelength electromagnetic wave scattering process from plasma prolate and oblate spheroids placed in a dielectric layer

    Science.gov (United States)

    Ahmadizadeh, Y.; Jazi, B.; Abdoli-Arani, A.

    2014-01-01

    Response of a prolate spheroid plasma and/or an oblate spheroid plasma in presence of long wavelength electromagnetic wave has been studied. The resonance frequencies of these objects are obtained and it is found that they reduce to the resonance frequency of spherical cold plasma. Moreover, the resonant frequencies of prolate spheroid plasma and oblate spheroid plasma covered by a dielectric are investigated as well. Furthermore, their dependency on dielectric permittivity and geometry dimensions is simulated.

  12. Breakup of the H2 molecule by xuv laser pulses: A time-dependent treatment in prolate spheroidal coordinates

    International Nuclear Information System (INIS)

    Guan Xiaoxu; Bartschat, Klaus; Schneider, Barry I

    2012-01-01

    We present theoretical predictions for one-photon double-ionization of H 2 by an xuv laser pulse. The results were obtained by solving the time-dependent Schrödinger equation in prolate spheroidal coordinates. Good agreement is obtained with predictions from other time-dependent and time-independent calculations, except for the recent 'exterior complex scaling' treatment by Tao et al. (Phys. Rev. A 82 023423).

  13. A Probe-Compensated Helicoidal NF-FF Transformation for Aperture Antennas Using a Prolate Spheroidal Expansion

    Directory of Open Access Journals (Sweden)

    Amedeo Capozzoli

    2012-01-01

    Full Text Available A new probe-compensated near-field-far-field (NF-FF transformation for aperture antennas in a cylindrical scanning geometry is presented. Such a technique takes the advantage of the NF data acquisition made according to a very efficient sampling strategy along a helix and exploits a proper aperture field expansion based on the use of the prolate spheroidal wave functions (PSWFs, accounting for the a priori information on shape and size of the antenna under test. The unknown aperture field expansion coefficients of the PSWFs are evaluated from the acquired voltage samples by an inversion process using a regularized version of the singular value decomposition method. Experimental results on connected and disconnected radiating aperture antennas, including sum and difference patterns, show the effectiveness of the approach and, in particular, how it enables a serious reduction of the measurement points without impairing the FF estimation accuracy.

  14. Analysis of long wavelength electromagnetic scattering by a magnetized cold plasma prolate spheroid

    Science.gov (United States)

    Ahmadizadeh, Yadollah; Jazi, Bahram; Abdoli-Arani, Abbas

    2013-08-01

    Using dielectric permittivity tensor of the magnetized prolate plasma, the scattering of long wavelength electromagnetic waves from the mentioned object is studied. The resonance frequency and differential scattering cross section for the backward scattered waves are presented. Consistency between the resonance frequency in this configuration and results obtained for spherical plasma are investigated. Finally, the effective factors on obtained results such as incident wave polarization, the frequency of the incident wave, the plasma frequency and the cyclotron frequency are analyzed.

  15. Optical properties of spherical and oblate spheroidal gold shell colloids

    NARCIS (Netherlands)

    Penninkhof, J.J.; Moroz, A.; van Blaaderen, A.; Polman, A.

    2008-01-01

    The surface plasmon modes of spherical and oblate spheroidal core−shell colloids composed of a 312 nm diameter silica core and a 20 nm thick Au shell are investigated. Large arrays of uniaxially aligned core−shell colloids with size aspect ratios ranging from 1.0 to 1.7 are fabricated using a novel

  16. Semi-analytical Karhunen-Loeve representation of irregular waves based on the prolate spheroidal wave functions

    Science.gov (United States)

    Lee, Gibbeum; Cho, Yeunwoo

    2018-01-01

    A new semi-analytical approach is presented to solving the matrix eigenvalue problem or the integral equation in Karhunen-Loeve (K-L) representation of random data such as irregular ocean waves. Instead of direct numerical approach to this matrix eigenvalue problem, which may suffer from the computational inaccuracy for big data, a pair of integral and differential equations are considered, which are related to the so-called prolate spheroidal wave functions (PSWF). First, the PSWF is expressed as a summation of a small number of the analytical Legendre functions. After substituting them into the PSWF differential equation, a much smaller size matrix eigenvalue problem is obtained than the direct numerical K-L matrix eigenvalue problem. By solving this with a minimal numerical effort, the PSWF and the associated eigenvalue of the PSWF differential equation are obtained. Then, the eigenvalue of the PSWF integral equation is analytically expressed by the functional values of the PSWF and the eigenvalues obtained in the PSWF differential equation. Finally, the analytically expressed PSWFs and the eigenvalues in the PWSF integral equation are used to form the kernel matrix in the K-L integral equation for the representation of exemplary wave data such as ordinary irregular waves. It is found that, with the same accuracy, the required memory size of the present method is smaller than that of the direct numerical K-L representation and the computation time of the present method is shorter than that of the semi-analytical method based on the sinusoidal functions.

  17. Numerical simulations of bistable flows in precessing spheroidal shells

    Science.gov (United States)

    Vormann, J.; Hansen, U.

    2018-05-01

    Precession of the rotation axis is an often neglected mechanical driving mechanism for flows in planetary interiors, through viscous coupling at the boundaries and topographic forcing in non-spherical geometries. We investigate precession-driven flows in spheroidal shells over a wide range of parameters and test the results against theoretical predictions. For Ekman numbers down to 8.0 × 10-7, we see a good accordance with the work of Busse, who assumed the precession-driven flow to be dominated by a rigid rotation component that is tilted to the main rotation axis. The velocity fields show localized small-scale structures for lower Ekman numbers and clear signals of inertial waves for some parameters. For the case of moderate viscosity and strong deformation, we report the realization of multiple solutions at the same parameter combination, depending on the initial condition.

  18. Axial acoustic radiation force on rigid oblate and prolate spheroids in Bessel vortex beams of progressive, standing and quasi-standing waves.

    Science.gov (United States)

    Mitri, F G

    2017-02-01

    The analysis using the partial-wave series expansion (PWSE) method in spherical coordinates is extended to evaluate the acoustic radiation force experienced by rigid oblate and prolate spheroids centered on the axis of wave propagation of high-order Bessel vortex beams composed of progressive, standing and quasi-standing waves, respectively. A coupled system of linear equations is derived after applying the Neumann boundary condition for an immovable surface in a non-viscous fluid, and solved numerically by matrix inversion after performing a single numerical integration procedure. The system of linear equations depends on the partial-wave index n and the order of the Bessel vortex beam m using truncated but converging PWSEs in the least-squares sense. Numerical results for the radiation force function, which is the radiation force per unit energy density and unit cross-sectional surface, are computed with particular emphasis on the amplitude ratio describing the transition from the progressive to the pure standing waves cases, the aspect ratio (i.e., the ratio of the major axis over the minor axis of the spheroid), the half-cone angle and order of the Bessel vortex beam, as well as the dimensionless size parameter. A generalized expression for the radiation force function is derived for cases encompassing the progressive, standing and quasi-standing waves of Bessel vortex beams. This expression can be reduced to other types of beams/waves such as the zeroth-order Bessel non-vortex beam or the infinite plane wave case by appropriate selection of the beam parameters. The results for progressive waves reveal a tractor beam behavior, characterized by the emergence of an attractive pulling force acting in opposite direction of wave propagation. Moreover, the transition to the quasi-standing and pure standing wave cases shows the acoustical tweezers behavior in dual-beam Bessel vortex beams. Applications in acoustic levitation, particle manipulation and acousto

  19. SIZE AND SHAPE FACTOR EXTREMES OF SPHEROIDS

    Directory of Open Access Journals (Sweden)

    Daniel Hlubinka

    2011-05-01

    Full Text Available In the paper we consider random prolate (oblate spheroids and their random profiles. The limiting distribution of the extremal characteristics of the spheroids is related to the limiting distribution of the corresponding extremal characteristics of the profiles. The difference between the analysis of the prolate and oblate spheroids is discussed. We propose the possible application of the theoretical results.

  20. Isotropic oscillator: spheroidal wave functions

    International Nuclear Information System (INIS)

    Mardoyan, L.G.; Pogosyan, G.S.; Ter-Antonyan, V.M.; Sisakyan, A.N.

    1985-01-01

    Solutions of the Schroedinger equation are found for an isotropic oscillator (10) in prolate and oblate spheroidal coordinates. It is shown that the obtained solutions turn into spherical and cylindrical bases of the isotropic oscillator at R→0 and R→ infinity (R is the dimensional parameter entering into the definition of prolate and oblate spheroidal coordinates). The explicit form is given for both prolate and oblate basis of the isotropic oscillator for the lowest quantum states

  1. Acoustic scattering on spheroidal shapes near boundaries

    Science.gov (United States)

    Miloh, Touvia

    2016-11-01

    A new expression for the Lamé product of prolate spheroidal wave functions is presented in terms of a distribution of multipoles along the axis of the spheroid between its foci (generalizing a corresponding theorem for spheroidal harmonics). Such an "ultimate" singularity system can be effectively used for solving various linear boundary-value problems governed by the Helmholtz equation involving prolate spheroidal bodies near planar or other boundaries. The general methodology is formally demonstrated for the axisymmetric acoustic scattering problem of a rigid (hard) spheroid placed near a hard/soft wall or inside a cylindrical duct under an axial incidence of a plane acoustic wave.

  2. Analytical study of spheroidal dust grains in plasma

    International Nuclear Information System (INIS)

    Zahed, H.; Mahmoodi, J.; Sobhanian, S.

    2006-01-01

    Using the modified spheroidal equations, the potential of a spheroidal conducting grain, floated in a plasma, is calculated. The electric field and capacitance for both prolate and oblate spheroidal grains are investigated. The solutions, obtained up to the second-order approximation, show that the plasma screening causes the equipotential surfaces around the grain to be more elongated or flattened than the potential spheroids of the Laplace equation. This leads to the variation of the plasma concentration around the grain

  3. Magnetohydrodynamic equilibrium with spheroidal plasma-vacuum interface

    International Nuclear Information System (INIS)

    Kaneko, Shobu; Chiyoda, Katsuji; Hirota, Isao.

    1983-01-01

    The Grad-Shafranov equations for an oblate and a prolate spheroidal plasmas are solved analytically under the assumptions, Bsub(phi) = 0 and dp/dpsi = constant. Here Bsub(phi) is the toroidal magnetic field, p is the kinetic pressure, and psi is the magnetic flux function. The plasmas in magnetohydrodynamic equilibrium are shown to be toroidal. The equilibrium magnetic-field configurations outside the spheroidal plasmas are considerably different from that of a spherical plasma. A line cusp or two point cusps appear outside the oblate or the prolate spheroidal plasma, respectively. (author)

  4. Electromagnetic characteristics of systems of prolate and oblate ellipsoids

    Science.gov (United States)

    Karimi, Pouyan; Amiri-Hezaveh, Amirhossein; Ostoja-Starzewski, Martin; Jin, Jian-Ming

    2017-11-01

    The present study suggests a novel model for simulating electromagnetic characteristics of spheroidal nanofillers. The electromagnetic interference shielding efficiency of prolate and oblate ellipsoids in the X-band frequency range is studied. Different multilayered nanocomposite configurations incorporating carbon nanotubes, graphene nanoplatelets, and carbon blacks are fabricated and tested. The best performance for a specific thickness is observed for the multilayered composite with a gradual increase in the thickness and electrical conductivity of layers. The simulation results based on the proposed model are shown to be in good agreement with the experimental data. The effect of filler alignment on shielding efficiency is also studied by using the nematic order parameter. The ability of a nanocomposite to shield the incident power is found to decrease by increasing alignment especially for high volume fractions of prolate fillers. The interaction of the electromagnetic wave and the fillers is mainly affected by the polarization of the electric field; when the electric field is perpendicular to the equatorial axis of a spheroid, the interaction is significantly reduced and results in a lower shielding efficiency. Apart from the filler alignment, size polydispersity is found to have a significant effect on reflected and transmitted powers. It is demonstrated that the nanofillers with a higher aspect ratio mainly contribute to the shielding performance. The results are of interest in both shielding structures and microwave absorbing materials.

  5. The prolate dark matter halo of the Andromeda galaxy

    Energy Technology Data Exchange (ETDEWEB)

    Hayashi, Kohei; Chiba, Masashi, E-mail: k.hayasi@astr.tohoku.ac.jp, E-mail: chiba@astr.tohoku.ac.jp [Astronomical Institute, Tohoku University, Aoba-ku, Sendai 980-8578 (Japan)

    2014-07-01

    We present new limits on the global shape of the dark matter halo in the Andromeda galaxy using and generalizing non-spherical mass models developed by Hayashi and Chiba and compare our results with theoretical predictions of cold dark matter (CDM) models. This is motivated by the fact that CDM models predict non-spherical virialized dark halos, which reflect the process of mass assembly in the galactic scale. Applying our models to the latest kinematic data of globular clusters and dwarf spheroidal galaxies in the Andromeda halo, we find that the most plausible cases for Andromeda yield a prolate shape for its dark halo, irrespective of assumed density profiles. We also find that this prolate dark halo in Andromeda is consistent with theoretical predictions in which the satellites are distributed anisotropically and preferentially located along major axes of their host halos. It is a reflection of the intimate connection between galactic dark matter halos and the cosmic web. Therefore, our result is profound in understanding internal dynamics of halo tracers in Andromeda, such as orbital evolutions of tidal stellar streams, which play important roles in extracting the abundance of CDM subhalos through their dynamical effects on stream structures.

  6. The prolate dark matter halo of the Andromeda galaxy

    International Nuclear Information System (INIS)

    Hayashi, Kohei; Chiba, Masashi

    2014-01-01

    We present new limits on the global shape of the dark matter halo in the Andromeda galaxy using and generalizing non-spherical mass models developed by Hayashi and Chiba and compare our results with theoretical predictions of cold dark matter (CDM) models. This is motivated by the fact that CDM models predict non-spherical virialized dark halos, which reflect the process of mass assembly in the galactic scale. Applying our models to the latest kinematic data of globular clusters and dwarf spheroidal galaxies in the Andromeda halo, we find that the most plausible cases for Andromeda yield a prolate shape for its dark halo, irrespective of assumed density profiles. We also find that this prolate dark halo in Andromeda is consistent with theoretical predictions in which the satellites are distributed anisotropically and preferentially located along major axes of their host halos. It is a reflection of the intimate connection between galactic dark matter halos and the cosmic web. Therefore, our result is profound in understanding internal dynamics of halo tracers in Andromeda, such as orbital evolutions of tidal stellar streams, which play important roles in extracting the abundance of CDM subhalos through their dynamical effects on stream structures.

  7. Translation and rotation of a porous spheroid in a spheroidal container

    International Nuclear Information System (INIS)

    Saad, E.I.

    2010-01-01

    The flow problem of an incompressible axisymmetrical quasisteady translation and steady rotation of a porous spheroid in a concentric spheroidal container are studied analytically. The same small departure from a sphere is considered for each spheroidal surface. In the limit of small Reynolds number, the Brinkman equation for the flow inside the porous region and the Stokes equation for the outside region in their stream functions formulations and velocity components, which are proportional to the translational and angular velocities, respectively, are used. Explicit expressions are obtained for both inside and outside flow fields to the first order in a small parameter characterizing the deformation of the spheroidal surface from the spherical shape. The hydrodynamic drag force and couple exerted on the porous spheroid are obtained for the special cases of prolate and oblate spheroids in closed forms. The dependence of the normalized wall-corrected translational and rotational mobilities on permeability for a porous spheroid in an unbounded medium and for a solid spheroid in a cell on the particle volume fraction is discussed numerically and graphically for various values of the deformation parameter. In the limiting cases, the analytical solutions describing the drag force and torque or mobilities for a porous spheroid in the spheroidal vessel reduce to those for a solid sphere and for a porous sphere in a spherical cell. (author)

  8. Tilted-ring models of the prolate spiral galaxies NGC 5033 and 5055

    Science.gov (United States)

    Christodoulou, Dimitris M.; Tohline, Joel E.; Steiman-Cameron, Thomas Y.

    1988-01-01

    Observations of the kinematics of H I in the disks of spiral galaxies have shown that isovelocity contours often exhibit a twisted pattern. The shape of a galaxy's gravitational potential well (whether due to luminous matter or dark matter) can be determined from the direction of the twist. If this twist is a manifestation of the precession of a nonsteady-state disk, it is shown that the twists of NGC 5033 and 5055 imply an overall prolate shape, with the major axis of the potential well aligned along the rotation axis of the disk. Therefore, the luminous disks of these galaxies must be embedded in dark halos that are prolate spheroids or prolatelike triaxial figures.

  9. Prolate dominant but oblate stable

    International Nuclear Information System (INIS)

    Girija, K.K.; Joseph, Antony

    2013-01-01

    This article discusses the yrast states of even-even nuclei in the isotopic chains 150-160 Dy, 150-160 Er and 150-160 Yb and thereby to study the shape and deformation dependence of ground state energy, exploring cranked Nilsson Strutinsky shell correction method and potential energy surface (PES) diagrams. The total energy calculations have been performed for the even-even nuclei of the isotopic chains 150-160 Dy, 150-160 Er and 150-160 Yb in the ground state. The range of triaxiality parameter used is 0-60 ° and a frequency range of 0-1.5 MeV is employed. The quadrupole deformation parameter ε 2 is varied from 0 to 1

  10. Quantum Monodromy in Prolate Ellipsoidal Billiards

    NARCIS (Netherlands)

    Waalkens, Holger; Dullin, Holger R.

    2002-01-01

    This is the third in a series of three papers on quantum billiards with elliptic and ellipsoidal boundaries. In the present paper we show that the integrable billiard inside a prolate ellipsoid has an isolated singular point in its bifurcation diagram and, therefore, exhibits classical and quantum

  11. Stability of force-free spheromak plasma in spheroidal flux conserver

    International Nuclear Information System (INIS)

    Kaneko, Shobu; Tsutsui, Hiroaki

    1988-01-01

    The Woltjer-Taylor method is applied to spheromak plasmas in spheroidal flux conservers. As models of the flux conserver, both oblate and prolate spheroidal vessels with a center conductor are used. The plasma is not assumed to be nearly spherical, and the Rayleigh-Ritz method and the finite element method are used to evaluate the eigenvalues. The oblate spheromak is shown to be stable irrespective of the shape of the flux conserver. Though the prolate spheromak is unstable if there is no center conductor, it can be stable if the center conductor is installed. (author)

  12. Stability of spheroidal spheromak plasma by use of force-free approximation

    International Nuclear Information System (INIS)

    Kaneko, Shobu; Tsutsui, Hiroaki.

    1987-09-01

    The Woltjer-Taylor method is applied to spheromak plasmas in spheroidal flux conservers. As models of the flux conserver, both oblate and prolate spheroidal vessels with a center conductor are used. The plasma is not assumed to be nearly spherical, and the Rayleigh-Ritz method and the finite element method are used to evaluate the eigenvalues. The oblate spheromak is shown to be stable irrespective of the shape of the flux conserver. Though the prolate spheromak is unstable if there is no center conductor, it can be stable if the center conductor is installed. (author)

  13. Prolate yrast cascade in 183Tl

    International Nuclear Information System (INIS)

    Reviol, W.; Carpenter, M. P.; Janssens, R. V. F.; Jenkins, D.; Toth, K. S.; Bingham, C. R.; Riedinger, L. L.; Weintraub, W.; Cizewski, J. A.; Lauritsen, T.

    2000-01-01

    The yrast sequence in 183 Tl has been studied for the first time in recoil-mass selected γ-ray spectroscopic measurements. A rotational-like cascade of seven transitions is established down to the band head with probable spin and parity (13/2 + ). Unlike in the adjacent odd-mass Tl nuclei, prompt γ decay from the yrast band to a lower lying weakly deformed (oblate) structure is not observed. These features are consistent with the predicted drop of the prolate band head in 183 Tl compared to 185 Tl. The implications for the prolate energy minimum in odd-mass Tl nuclei at the neutron i 13/2 midshell (N=103) are discussed. (c) 2000 The American Physical Society

  14. Axisymmetric scattering of an acoustical Bessel beam by a rigid fixed spheroid

    OpenAIRE

    Mitri, F. G.

    2015-01-01

    Based on the partial-wave series expansion (PWSE) method in spherical coordinates, a formal analytical solution for the acoustic scattering of a zeroth-order Bessel acoustic beam centered on a rigid fixed (oblate or prolate) spheroid is provided. The unknown scattering coefficients of the spheroid are determined by solving a system of linear equations derived for the Neumann boundary condition. Numerical results for the modulus of the backscattered pressure (\\theta = \\pi) in the near-field an...

  15. Acoustic scattering of a Bessel vortex beam by a rigid fixed spheroid

    Science.gov (United States)

    Mitri, F. G.

    2015-12-01

    Partial-wave series representation of the acoustic scattering field of high-order Bessel vortex beams by rigid oblate and prolate spheroids using the modal matching method is developed. The method, which is applicable to slightly elongated objects at low-to-moderate frequencies, requires solving a system of linear equations which depends on the partial-wave index n and the order of the Bessel vortex beam m using truncated partial-wave series expansions (PWSEs), and satisfying the Neumann boundary condition for a rigid immovable surface in the least-squares sense. This original semi-analytical approach developed for Bessel vortex beams is demonstrated for finite oblate and prolate spheroids, where the mathematical functions describing the spheroidal geometry are written in a form involving single angular (polar) integrals that are numerically computed. The transverse (θ = π / 2) and 3D scattering directivity patterns are evaluated in the far-field for both prolate and oblate spheroids, with particular emphasis on the aspect ratio (i.e., the ratio of the major axis over the minor axis of the spheroid) not exceeding 3:1, the half-cone angle β and order m of the Bessel vortex beam, as well as the dimensionless size parameter kr0. Periodic oscillations in the magnitude plots of the far-field scattering form function are observed, which result from the interference of the reflected waves with the circumferential (Franz') waves circumnavigating the surface of the spheroid in the surrounding fluid. Moreover, the 3D directivity patterns illustrate the far-field scattering from the spheroid, that vanishes in the forward (θ = 0) and backward (θ = π) directions. Particular applications in underwater acoustics and scattering, acoustic levitation and the detection of submerged elongated objects using Bessel vortex waves to name a few, would benefit from the results of the present investigation.

  16. The Origin of Prolate Rotation in Dwarf Spheroidal Galaxies Formed by Mergers of Disky Dwarfs

    Czech Academy of Sciences Publication Activity Database

    Ebrová, Ivana; Lokas, E.

    2015-01-01

    Roč. 813, č. 1 (2015), 10/1-10/15 ISSN 0004-637X Institutional support: RVO:67985815 Keywords : galaxies * fundamental parameters * kinematics and dynamics Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 5.909, year: 2015

  17. Prolate-Spheroid ('Rugby-Shaped') Hohlraum for Inertial Confinement Fusion

    International Nuclear Information System (INIS)

    Vandenboomgaerde, M.; Bastian, J.; Casner, A.; Galmiche, D.; Jadaud, J.-P.; Laffite, S.; Liberatore, S.; Malinie, G.; Philippe, F.

    2007-01-01

    A novel rugby-ball shaped hohlraum is designed in the context of the indirect-drive scheme of inertial-confinement fusion (ICF). Experiments were performed on the OMEGA laser and are the first use of rugby hohlraums for ICF studies. Analysis of experimental data shows that the hohlraum energetics is well understood. We show that the rugby-ball shape exhibits advantages over cylinder, in terms of temperature and of symmetry control of the capsule implosion. Simulations indicate that rugby hohlraum driven targets may be candidates for ignition in a context of early Laser MegaJoule experiments with reduced laser energy

  18. Strain-Driven Stacking Faults in CdSe/CdS Core/Shell Nanorods.

    Science.gov (United States)

    Demortière, Arnaud; Leonard, Donovan N; Petkov, Valeri; Chapman, Karena; Chattopadhyay, Soma; She, Chunxing; Cullen, David A; Shibata, Tomohiro; Pelton, Matthew; Shevchenko, Elena V

    2018-04-19

    Colloidal semiconductor nanocrystals are commonly grown with a shell of a second semiconductor material to obtain desired physical properties, such as increased photoluminescence quantum yield. However, the growth of a lattice-mismatched shell results in strain within the nanocrystal, and this strain has the potential to produce crystalline defects. Here, we study CdSe/CdS core/shell nanorods as a model system to investigate the influence of core size and shape on the formation of stacking faults in the nanocrystal. Using a combination of high-angle annular dark-field scanning transmission electron microscopy and pair-distribution-function analysis of synchrotron X-ray scattering, we show that growth of the CdS shell on smaller, spherical CdSe cores results in relatively small strain and few stacking faults. By contrast, growth of the shell on larger, prolate spheroidal cores leads to significant strain in the CdS lattice, resulting in a high density of stacking faults.

  19. Axisymmetric scattering of an acoustical Bessel beam by a rigid fixed spheroid.

    Science.gov (United States)

    Mitri, Farid G

    2015-10-01

    Based on the partial-wave series expansion (PWSE) method in spherical coordinates, a formal analytical solution for the acoustic scattering of a zeroth-order Bessel acoustic beam centered on a rigid fixed (oblate or prolate) spheroid is provided. The unknown scattering coefficients of the spheroid are determined by solving a system of linear equations derived for the Neumann boundary condition. Numerical results for the modulus of the backscattered pressure (θ = π) in the near field and the backscattering form function in the far field for both prolate and oblate spheroids are presented and discussed, with particular emphasis on the aspect ratio (i.e., the ratio of the major axis over the minor axis of the spheroid), the half-cone angle of the Bessel beam, and the dimensionless frequency. The plots display periodic oscillations (versus the dimensionless frequency) because of the interference of specularly reflected waves in the backscattering direction with circumferential Franz' waves circumnavigating the surface of the spheroid in the surrounding fluid. Moreover, the 3-D directivity patterns illustrate the near- and far-field axisymmetric scattering. Investigations in underwater acoustics, particle levitation, scattering, and the detection of submerged elongated objects and other related applications utilizing Bessel waves would benefit from the results of the present study.

  20. Multipoles and Force on External Points for a Two-layered Spheroidal Liquid Mass Rotating Differentialy

    Energy Technology Data Exchange (ETDEWEB)

    Cisneros-Parra, Joel U. [Facultad de Ciencias, UASLP, Zona Universitaria, San Luis Potosi, S,L,P, 78290 (Mexico); Martinez-Herrera, Francisco J.; Montalvo-Castro, J. Daniel [Instituto de Fisica, UASLP, Zona Universitaria, San Luis Potosi, S,L,P, 78290 (Mexico)

    2017-10-20

    We recently reported on a series of equilibrium figures for a self-gravitating heterogeneous liquid body, consisting of two concentric distorted spheroids, “nucleus” and “atmosphere,” each endowed with its own internal motion of differential rotation. In our current work, we calculate the body’s force at external points and obtain a multipolar expansion of the potential. We also give an account of figures with prolate nuclei, which remained unnoticed by us in our former paper.

  1. Axisymmetric force-free states and relaxation of a spheroidal spheromak

    International Nuclear Information System (INIS)

    Throumoulopoulos, G.N.; Pantis, G.

    1990-01-01

    Axisymmetric force-free equilibrium eigenstates for a prolate as well as an oblate spheroidal Spheromak with arbitrary elongation are obtained. In the framework of the Woltjer-Taylor relaxation theory the relaxed states are also identified. A simple hypothesis for the relaxation process is introduced, which implies that the plasma relaxes from multitoroidal formations to a singly toroidal configuration, in qualitative agreement with experimental results. (author)

  2. Multipoles and Force on External Points for a Two-layered Spheroidal Liquid Mass Rotating Differentialy

    International Nuclear Information System (INIS)

    Cisneros-Parra, Joel U.; Martinez-Herrera, Francisco J.; Montalvo-Castro, J. Daniel

    2017-01-01

    We recently reported on a series of equilibrium figures for a self-gravitating heterogeneous liquid body, consisting of two concentric distorted spheroids, “nucleus” and “atmosphere,” each endowed with its own internal motion of differential rotation. In our current work, we calculate the body’s force at external points and obtain a multipolar expansion of the potential. We also give an account of figures with prolate nuclei, which remained unnoticed by us in our former paper.

  3. Axisymmetric force-free states and relaxation of a spheroidal spheromak

    International Nuclear Information System (INIS)

    Throumoulopoulos, G.N.; Pantis, G.

    1990-01-01

    Axisymmetric force-free equilibrium eigenstates for a prolate as well as an oblate spheroidal spheromak with arbitrary elongation are obtained. In the framework of the Woltjer-Taylor relaxation theory the relaxed states are also identified. A simple hypothesis for the relaxation process is introduced which implies that the plasma relaxes from multitoroidal formations to a singly toroidal configuration in qualitative agreement with experimental results. (Author)

  4. Encapsulation by Janus spheroids

    OpenAIRE

    Li, Wei; Liu, Ya; Brett, Genevieve; Gunton, James D.

    2011-01-01

    The micro/nano encapsulation technology has acquired considerable attention in the fields of drug delivery, biomaterial engineering, and materials science. Based on recent advances in chemical particle synthesis, we propose a primitive model of an encapsulation system produced by the self-assembly of Janus oblate spheroids, particles with oblate spheroidal bodies and two hemi-surfaces coded with dissimilar chemical properties. Using Monte Carlo simulation, we investigate the encapsulation sys...

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

    International Nuclear Information System (INIS)

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

    1982-01-01

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

  6. Magnetohydrodynamic equilibrium and stability of spheromak with spheroidal plasma-vacuum interface

    International Nuclear Information System (INIS)

    Kaneko, Shobu; Kamitani, Atsushi; Takimoto, Akio.

    1985-05-01

    The analytic solutions to the Grad-Shafranov equation are obtained for a prolate and an oblate spheroidal plasma by using Hill's vortex model. Effects of a toroidal magnetic field Bsub(phi) on the MHD equilibrium configurations are investigated by using these analytic solutions. When Bsub(phi) is larger than that of the force-free configuration, the spheroidal plasmas in a vacuum magnetic field are shown to be unable in the MHD equilibrium. The several physical quantities on the equilibrium configuration are evaluated. The spheromak plasma is proved to be unstable if dp/d psi not equal 0 and d 2 V/d psi 2 >= 0 on the magnetic axis. Here p is the pressure and V(psi) the volume surrounded by a magnetic surface of psi=const. The equilibrium configurations of the spheroidal plasmas by using Hill's vortex model are shown to satisfy the above conditions, i.e., to be unstable. (author)

  7. Magnetohydrodynamic equilibrium and stability of spheromak with spheroidal plasma-vacuum interface

    International Nuclear Information System (INIS)

    Kaneko, Shobu; Kamitani, Atsushi; Takimoto, Akio

    1985-01-01

    The analytic solutions to the Grad-Shafranov equation are obtained for a prolate and an oblate spheroidal plasma by using Hill's vortex model. Effects of a toroidal magnetic field Bsub(phi) on the MHD equilibrium configurations are investigated by using these analytic solutions. When Bsub(phi) is stronger than that of the force-free configuration, the spheroidal plasmas in a vacuum magnetic field are shown to be unable in the MHD equilibrium. The several physical quantities on the equilibrium configuration are evaluated. The spheromak plasma is proved to be unstable if dp/d psi not equal 0 and d 2 V/d psi 2 >= 0 on the magnetic axis. Here p is the pressure and V(psi) the volume surrounded by a magnetic surface of psi = const. The equilibrium configurations of the spheroidal plasmas by using Hill's vortex model are shown to satisfy the above conditions, i.e., to be unstable. (author)

  8. Arbitrary scattering of an acoustical Bessel beam by a rigid spheroid with large aspect-ratio

    Science.gov (United States)

    Gong, Zhixiong; Li, Wei; Mitri, Farid G.; Chai, Yingbin; Zhao, Yao

    2016-11-01

    In this paper, the T-matrix (null-field) method is applied to investigate the acoustic scattering by a large-aspect-ratio rigid spheroid immersed in a non-viscous fluid under the illumination of an unbounded zeroth-order Bessel beam with arbitrary orientation. Based on the proposed method, a MATLAB software package is constructed accordingly, and then verified and validated to compute the acoustic scattering by a rigid oblate or prolate spheroid in the Bessel beam. Several numerical examples are carried out to investigate the novel phenomenon of acoustic scattering by spheroids in Bessel beams with arbitrary incidence, with particular emphasis on the aspect ratio (i.e. the ratio of the polar radius over the equatorial radius of the spheroid), the half-cone angle of Bessel beam, the dimensionless frequency, as well as the angle of incidence. The quasi-periodic oscillations are observed in the plots of the far-field backscattering form function modulus versus the dimensionless frequency, owing to the interference between the specular reflection and the Franz wave circumnavigating the spheroid in the surrounding fluid. Furthermore, the 3D far-field scattering directivity patterns at end-on incidence and 2D polar plots at arbitrary angles of incidence are exhibited, which could provide new insights into the physical mechanisms of Bessel beam scattering by flat or elongated spheroid. This research work may provide an impetus for the application of acoustic Bessel beam in engineering practices.

  9. On the swimming motion of spheroidal magnetotactic bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Cui Zhen; Kong Dali; Zhang Keke [Department of Mathematical Sciences, University of Exeter, Exeter EX4 4QF (United Kingdom); Pan Yongxin, E-mail: kzhang@ex.ac.uk [Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing (China)

    2012-10-15

    We investigate, via both theoretical and experimental methods, the swimming motion of magnetotactic bacteria having the shape of an elongated prolate spheroid in a viscous liquid under the influence of an imposed magnetic field. A fully three-dimensional Stokes flow, driven by the translation and rotation of a swimming bacterium, exerts a complicated viscous drag/torque on the motion of a non-spherical bacterium. By assuming that the body of the bacterium is non-deformable and that the interaction between different bacteria is weak and hence negligible, we have derived a system of 12 coupled nonlinear ordinary differential equations that govern both the motion and the orientation of a swimming spheroidal magnetotactic bacterium. The focus of the study is on how the shape of a non-spherical magnetotactic bacterium, marked by the size of its eccentricity, affects the pattern of its swimming motion. It is revealed that the pattern/speed of a swimming spheroidal magnetotactic bacterium is highly sensitive not only to the direction of its magnetic moment but also to its shape. We also compare the theoretical pattern obtained from the solutions of the 12 coupled differential equations with that observed in the laboratory experiments using the magnetotactic bacteria found in Lake Miyun near Beijing, China, showing that the observed pattern can be largely reproduced with an appropriate set of parameters in our theoretical model. (paper)

  10. On the swimming motion of spheroidal magnetotactic bacteria

    International Nuclear Information System (INIS)

    Cui Zhen; Kong Dali; Zhang Keke; Pan Yongxin

    2012-01-01

    We investigate, via both theoretical and experimental methods, the swimming motion of magnetotactic bacteria having the shape of an elongated prolate spheroid in a viscous liquid under the influence of an imposed magnetic field. A fully three-dimensional Stokes flow, driven by the translation and rotation of a swimming bacterium, exerts a complicated viscous drag/torque on the motion of a non-spherical bacterium. By assuming that the body of the bacterium is non-deformable and that the interaction between different bacteria is weak and hence negligible, we have derived a system of 12 coupled nonlinear ordinary differential equations that govern both the motion and the orientation of a swimming spheroidal magnetotactic bacterium. The focus of the study is on how the shape of a non-spherical magnetotactic bacterium, marked by the size of its eccentricity, affects the pattern of its swimming motion. It is revealed that the pattern/speed of a swimming spheroidal magnetotactic bacterium is highly sensitive not only to the direction of its magnetic moment but also to its shape. We also compare the theoretical pattern obtained from the solutions of the 12 coupled differential equations with that observed in the laboratory experiments using the magnetotactic bacteria found in Lake Miyun near Beijing, China, showing that the observed pattern can be largely reproduced with an appropriate set of parameters in our theoretical model. (paper)

  11. Prolate non-collective shape- a rare shape phase around Z = 50

    International Nuclear Information System (INIS)

    Aggarwal, Mamta

    2009-01-01

    The search for rare shape-phase transition in hot and rotating nuclei is one of the very active field in nuclear physics research. According to universally known features of the evolution of equilibrium shapes with temperature and spin, heating a deformed nonrotating nucleus leads to a shape transition from deformed to spherical at a certain temperature. At high temperatures T≅ 2 MeV, the shell effects melt and the nucleus resembles a classical liquid drop. Rotation of the hot nucleus generates an oblate shape rotating noncollectively. But it has been shown by A. Goodman that nuclei with two critical temperatures can rotate with a rare non-collective prolate shape phase which has been caused directly by rotation at angular momentum values around (5-30h) which creates a residual quantum shell effect as shown by A. L. Goodman. Search for such exotic shape-phase around Z = 50 region is the aim of present work. We consider N = 60 isotones 108 Cd, 109 In, 110 Sn

  12. Chitosan derived co-spheroids of neural stem cells and mesenchymal stem cells for neural regeneration.

    Science.gov (United States)

    Han, Hao-Wei; Hsu, Shan-Hui

    2017-10-01

    Chitosan has been considered as candidate biomaterials for neural applications. The effective treatment of neurodegeneration or injury to the central nervous system (CNS) is still in lack nowadays. Adult neural stem cells (NSCs) represents a promising cell source to treat the CNS diseases but they are limited in number. Here, we developed the core-shell spheroids of NSCs (shell) and mesenchymal stem cells (MSCs, core) by co-culturing cells on the chitosan surface. The NSCs in chitosan derived co-spheroids displayed a higher survival rate than those in NSC homo-spheroids. The direct interaction of NSCs with MSCs in the co-spheroids increased the Notch activity and differentiation tendency of NSCs. Meanwhile, the differentiation potential of MSCs in chitosan derived co-spheroids was significantly enhanced toward neural lineages. Furthermore, NSC homo-spheroids and NSC/MSC co-spheroids derived on chitosan were evaluated for their in vivo efficacy by the embryonic and adult zebrafish brain injury models. The locomotion activity of zebrafish receiving chitosan derived NSC homo-spheroids or NSC/MSC co-spheroids was partially rescued in both models. Meanwhile, the higher survival rate was observed in the group of adult zebrafish implanted with chitosan derived NSC/MSC co-spheroids as compared to NSC homo-spheroids. These evidences indicate that chitosan may provide an extracellular matrix-like environment to drive the interaction and the morphological assembly between NSCs and MSCs and promote their neural differentiation capacities, which can be used for neural regeneration. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Modeling single-scattering properties of small cirrus particles by use of a size-shape distribution of ice spheroids and cylinders

    International Nuclear Information System (INIS)

    Liu Li; Mishchenko, Michael I.; Cairns, Brian; Carlson, Barbara E.; Travis, Larry D.

    2006-01-01

    In this study, we model single-scattering properties of small cirrus crystals using mixtures of polydisperse, randomly oriented spheroids and cylinders with varying aspect ratios and with a refractive index representative of water ice at a wavelength of 1.88 μm. The Stokes scattering matrix elements averaged over wide shape distributions of spheroids and cylinders are compared with those computed for polydisperse surface-equivalent spheres. The shape-averaged phase function for a mixture of oblate and prolate spheroids is smooth, featureless, and nearly flat at side-scattering angles and closely resembles those typically measured for cirrus. Compared with the ensemble-averaged phase function for spheroids, that for a shape distribution of cylinders shows a relatively deeper minimum at side-scattering angles. This may indicate that light scattering from realistic cirrus crystals can be better represented by a shape mixture of ice spheroids. Interestingly, the single-scattering properties of shape-averaged oblate and prolate cylinders are very similar to those of compact cylinders with a diameter-to-length ratio of unity. The differences in the optical cross sections, single-scattering albedo, and asymmetry parameter between the spherical and the nonspherical particles studied appear to be relatively small. This may suggest that for a given optical thickness, the influence of particle shape on the radiative forcing caused by a cloud composed of small ice crystals can be negligible

  14. Neutron diffusion in spheroidal, bispherical, and toroidal systems

    International Nuclear Information System (INIS)

    Williams, M.M.R.

    1986-01-01

    The neutron flux has been studied around absorbing bodies of spheroidal, bispherical, and toroidal shapes in an infinite nonabsorbing medium. Exact solutions have been obtained by using effective boundary conditions at the surfaces of the absorbing bodies. The problems considered are as follows: 1. Neutron flux and current distributions around prolate and oblate spheroids. It is shown that an equivalent sphere approximation can lead to accurate values for the rate of absorption. 2. Neutron flux and current in a bispherical system of unequal spheres. Three separate situations arise here: (a) two absorbing spheres, (b) two spherical sources, and (c) one spherical source and one absorbing sphere. It is shown how the absorption rate in the two spheres depends on their separation. 3. Neutron flux and current in a toroidal system: (a) an absorbing toroid and (b) a toroidal source. The latter case simulates the flux distribution from a thermonuclear reactor vessel. Finally, a brief description of how these techniques can be extended to multiregion problems is given

  15. Needlelike motion of prolate ellipsoids in the sea of spheres

    Science.gov (United States)

    Vasanthi, R.; Ravichandran, S.; Bagchi, Biman

    2001-05-01

    Molecular dynamics simulations of translational motion of isolated prolate ellipsoids in the sea of spheres have been carried out for several different values of the aspect ratio (κ), obtained by changing either the length or the diameter of the ellipsoids, at several different solvent densities. The interaction among the spheres is given by the Lennard-Jones pair potential while that between spheres and ellipsoids is given by a modified Gay-Berne potential. Both the mean-square displacements of the center of mass of the ellipsoids and their orientational time correlation function have been calculated. It is found that at short to intermediate times, the motion of ellipsoids is anisotropic and primarily needlelike—the molecules prefer to move parallel to their long axis. The ratio of these two diffusion constants (D∥ and D⊥) approaches κ, suggesting a decoupling of D∥ from the length of the ellipsoid. The diffusion becomes isotropic in the long time with the total diffusion coefficient given by D∥+2D⊥. The crossover from the anisotropic to the isotropic diffusion is surprisingly sharp and clear in most cases.

  16. Formation and field-driven dynamics of nematic spheroids.

    Science.gov (United States)

    Fu, Fred; Abukhdeir, Nasser Mohieddin

    2017-07-19

    Unlike the canonical application of liquid crystals (LCs), LC displays, emerging technologies based on LC materials are increasingly leveraging the presence of nanoscale defects. The inherent nanoscale characteristics of LC defects present both significant opportunities as well as barriers for the application of this fascinating class of materials. Simulation-based approaches to the study of the effects of confinement and interface anchoring conditions on LC domains has resulted in significant progress over the past decade, where simulations are now able to access experimentally-relevant length scales while simultaneously capturing nanoscale defect structures. In this work, continuum simulations were performed in order to study the dynamics of micron-scale nematic LC spheroids of varying shape. Nematic spheroids are one of the simplest inherently defect-containing LC structures and are relevant to polymer-dispersed LC-based "smart" window technology. Simulation results include nematic phase formation and external field-switching dynamics of nematic spheroids ranging in shape from oblate to prolate. Results include both qualitative and quantitative insight into the complex coupling of nanoscale defect dynamics and structure transitions to micron-scale reorientation. Dynamic mechanisms are presented and related to structural transitions in LC defects present in the nematic domain. Domain-averaged metrics including order parameters and response times are determined for a range of experimentally-accessible electric field strengths. These results have both fundamental and technological relevance, in that increased understanding of LC dynamics in the presence of defects is a key barrier to continued advancement in the field.

  17. The Andromeda Dwarf Spheroidal Galaxies

    OpenAIRE

    Armandroff, Taft E.; Da Costa, Gary S.

    1998-01-01

    Our current knowledge of M31's dwarf spheroidal companions is reviewed. Two topics of recent interest constitute the bulk of this review. First, color-magnitude diagrams reaching below the horizontal branch have been constructed for two M31 dwarf spheroidals based on images from HST/WFPC2. The horizontal branches are predominantly red in both galaxies, redder than expected for their metallicity based on Galactic globular clusters. Thus, the second parameter effect is seen in the M31 halo. Sec...

  18. Radiobiological studies of cells in multicellular spheroids using a sequential trypsinization technique

    International Nuclear Information System (INIS)

    Giesbrecht, J.L.; Wilson, W.R.; Hill, R.P.

    1981-01-01

    The radiation response of V79 Chinese hamster cells grown as multicellular spheroids has been investigated by determining survival curves for treatment under a variety of different oxygen concentrations. Spheroids were irradiated under fully oxygenated conditions in air-equilibrated medium at 37 0 C, in medium exposed to lower oxygen tension (5% O 2 ) for times varying from 1 hr to 3 days, or under anoxic conditions. For comparison with the spheroids, using identical treatment conditions, V79 cells were grown in suspension as a subconfluent monolayer attached to Sephadex (microcarrier) beads and irradiated under fully oxygenated or anoxic conditions. The radiation response of cells at different depths within the spheroid was investigated by using a sequential trypsinization technique developed to remove eight or nine shells of cells successively from the spheroid surface. When irradiation was given under fully oxygenated conditions the outer few cell layers were more sensitive than the inner cells, a finding which is not understood. As expected the inner cells in spheroids irradiated in air (at 37 0 C) or in 5% O 2 are more resistant than the outer cells. For an acute exposure to 5% O 2 (1 hr) in the inner cells displayed full radiobiological hypoxia; however, for chronic exposures to low oxygen this was not the case. These results with the sequential trypsinization procedure suggest that the radiation response of cells in spheroids is more complex than anticipted

  19. RF induction plasma spheroidization of tungsten powders

    International Nuclear Information System (INIS)

    Gu Zhogntao; Ye Gaoying; Liu Chuandong; Tong Honghui

    2009-01-01

    Irregularly-shaped tungsten powders (average granular sizes of 512 μm) have been spheroidized by radio frequency (RF)induction plasma. The effects of feed rate, mode of material dispersion, particle size on spheroidization efficiency are investigated. Experimental results show that the spheroidization efficiency decreases rapidly when the feed rate increases to more than 95 g/min. Only 30% spheroidization efficiency is gained at the feed rate of 135.75 g/min. The spheroidization efficiency is also affected by the flow rate of carrier gas. When the flow rate of carrier gas is 0.12 m 3 /h, the dispersion effect is the best, and the spheroidization efficiency is almost 100%. The apparent density of tungsten powders increases a bit with the increase of spheroidization efficiency. And the particle size uniformity of spheroidized tungsten powders is in accordance with that of original powders. (authors)

  20. The role of spin-orbit potential in nuclear prolate-shape dominance

    Energy Technology Data Exchange (ETDEWEB)

    Takahara, Satoshi, E-mail: staka@ks.kyorin-u.ac.jp [Kyorin University, School of Medicine, Mitaka, Tokyo 181-8611 (Japan); Onishi, Naoki [University of Tokyo (Japan); University of Yamanashi (Japan); Shimizu, Yoshifumi R. [Department of Physics, Graduate School of Science, Kyushu University, Fukuoka 812-8581 (Japan); Tajima, Naoki [Department of Applied Physics, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507 (Japan)

    2011-08-26

    It is confirmed, in terms of the Woods-Saxon-Strutinsky method, that the spin-orbit potential plays a decisive role in the predominance of prolate deformation, which has been a long standing problem in nuclear physics. It is originated from the combined effects of the spin-orbit coupling and the diffused surface of the potential, in agreement with the previous work based on a more schematic Nilsson-Strutinsky method. The degree of prolate-shape dominance exhibits an oscillatory behavior with respect to the strength of spin-orbit potential and, the prolate-shape dominance is realized at the proper strength of the spin-orbit potential together with the standard surface diffuseness; this oscillatory behavior disappears in case of small diffuseness corresponding to ellipsoidal cavity. The calculated energy differences between oblate and prolate minima in this Letter are consistent with those of our extensive self-consistent calculations of the Hartree-Fock + BCS method with the Skyrme interaction.

  1. The role of spin-orbit potential in nuclear prolate-shape dominance

    International Nuclear Information System (INIS)

    Takahara, Satoshi; Onishi, Naoki; Shimizu, Yoshifumi R.; Tajima, Naoki

    2011-01-01

    It is confirmed, in terms of the Woods-Saxon-Strutinsky method, that the spin-orbit potential plays a decisive role in the predominance of prolate deformation, which has been a long standing problem in nuclear physics. It is originated from the combined effects of the spin-orbit coupling and the diffused surface of the potential, in agreement with the previous work based on a more schematic Nilsson-Strutinsky method. The degree of prolate-shape dominance exhibits an oscillatory behavior with respect to the strength of spin-orbit potential and, the prolate-shape dominance is realized at the proper strength of the spin-orbit potential together with the standard surface diffuseness; this oscillatory behavior disappears in case of small diffuseness corresponding to ellipsoidal cavity. The calculated energy differences between oblate and prolate minima in this Letter are consistent with those of our extensive self-consistent calculations of the Hartree-Fock + BCS method with the Skyrme interaction.

  2. Theory and computation of spheroidal wavefunctions

    International Nuclear Information System (INIS)

    Falloon, P E; Abbott, P C; Wang, J B

    2003-01-01

    In this paper we report on a package, written in the Mathematica computer algebra system, which has been developed to compute the spheroidal wavefunctions of Meixner and Schaefke (1954 Mathieusche Funktionen und Sphaeroidfunktionen) and is available online (physics.uwa.edu.au/~falloon/spheroidal/spheroidal.html). This package represents a substantial contribution to the existing software, since it computes the spheroidal wavefunctions to arbitrary precision for general complex parameters μ, ν, γ and argument z; existing software can only handle integer μ, ν and does not give arbitrary precision. The package also incorporates various special cases and computes analytic power series and asymptotic expansions in the parameter γ. The spheroidal wavefunctions of Flammer (1957 Spheroidal Wave functions) are included as a special case of Meixner's more general functions. This paper presents a concise review of the general theory of spheroidal wavefunctions and a description of the formulae and algorithms used in their computation, and gives high precision numerical examples

  3. Variable property, steady, axi-symmetric, laminar, continuum plasma flow over spheroidal particles

    International Nuclear Information System (INIS)

    Wen Yuemin; Jog, Milind A.

    2005-01-01

    Steady, continuum, laminar plasma flow over spheroidal particles has been numerically investigated in this paper using a finite volume method. To body-fit the non-spherical particle surface, an adaptive orthogonal grid is generated. The flow field and the temperature distribution are calculated for oblate and prolate particle shapes. A number of particle surface temperatures and far field temperatures are considered and thermo-physical property variation is fully accounted for in our model. The particle shapes are represented in terms of axis ratio which is defined as the ratio of axis perpendicular to the flow direction to the axis along the flow direction. For oblate shape, axis ratios from 1.6 (disk-like) to 1 (sphere) are used whereas for prolate shape, axis ratios of 1(sphere) to 0.4 (cylinder-like) are used. Effects of flow Reynolds number, particle shape, surface and far field temperatures, and variable properties, on the flow field, temperature variations, drag coefficient, and Nusselt number are outlined. Results show that particle shape has significant effect on flow and heat transfer to particle surface. Compared to a constant property flow, accounting for thermo-physical property variation leads to prediction of higher temperature and velocity gradients in the vicinity of the particle surface. Based on the numerical results, a correlation for the Nusslet number is proposed that accounts for the effect of particle shape in continuum flow with large thermo-physical property variation

  4. Identification of the host determinant of two prolate-headed phages infecting lactococcus lactis

    International Nuclear Information System (INIS)

    Stuer-Lauridsen, Birgitte; Janzen, Thomas; Schnabl, Jannie; Johansen, Eric

    2003-01-01

    A gene responsible for host determination was identified in two prolate-headed bacteriophages of the c2 species infecting strains of Lactococcus lactis. The identification of the host determinant gene was based on low DNA sequence homology in a specific open reading frame (ORF) between prolate-headed phages with different host ranges. When a host carrying this ORF from one phage on a plasmid was infected with another phage, we obtained phages with an altered host range at a frequency of 10 -6 to 10 -7 . Sequencing of phage DNA originating from 10 independent single plaques confirmed that a genetic recombination had taken place at different positions between the ORF on the plasmid and the infecting phage. The adsorption of the recombinant phages to their bacterial hosts had also changed to match the phage origin of the ORF. Consequently, it is concluded that this ORF codes for the host range determinant

  5. Scalable robotic biofabrication of tissue spheroids

    International Nuclear Information System (INIS)

    Mehesz, A Nagy; Hajdu, Z; Visconti, R P; Markwald, R R; Mironov, V; Brown, J; Beaver, W; Da Silva, J V L

    2011-01-01

    Development of methods for scalable biofabrication of uniformly sized tissue spheroids is essential for tissue spheroid-based bioprinting of large size tissue and organ constructs. The most recent scalable technique for tissue spheroid fabrication employs a micromolded recessed template prepared in a non-adhesive hydrogel, wherein the cells loaded into the template self-assemble into tissue spheroids due to gravitational force. In this study, we present an improved version of this technique. A new mold was designed to enable generation of 61 microrecessions in each well of a 96-well plate. The microrecessions were seeded with cells using an EpMotion 5070 automated pipetting machine. After 48 h of incubation, tissue spheroids formed at the bottom of each microrecession. To assess the quality of constructs generated using this technology, 600 tissue spheroids made by this method were compared with 600 spheroids generated by the conventional hanging drop method. These analyses showed that tissue spheroids fabricated by the micromolded method are more uniform in diameter. Thus, use of micromolded recessions in a non-adhesive hydrogel, combined with automated cell seeding, is a reliable method for scalable robotic fabrication of uniform-sized tissue spheroids.

  6. Scalable robotic biofabrication of tissue spheroids

    Energy Technology Data Exchange (ETDEWEB)

    Mehesz, A Nagy; Hajdu, Z; Visconti, R P; Markwald, R R; Mironov, V [Advanced Tissue Biofabrication Center, Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, SC (United States); Brown, J [Department of Mechanical Engineering, Clemson University, Clemson, SC (United States); Beaver, W [York Technical College, Rock Hill, SC (United States); Da Silva, J V L, E-mail: mironovv@musc.edu [Renato Archer Information Technology Center-CTI, Campinas (Brazil)

    2011-06-15

    Development of methods for scalable biofabrication of uniformly sized tissue spheroids is essential for tissue spheroid-based bioprinting of large size tissue and organ constructs. The most recent scalable technique for tissue spheroid fabrication employs a micromolded recessed template prepared in a non-adhesive hydrogel, wherein the cells loaded into the template self-assemble into tissue spheroids due to gravitational force. In this study, we present an improved version of this technique. A new mold was designed to enable generation of 61 microrecessions in each well of a 96-well plate. The microrecessions were seeded with cells using an EpMotion 5070 automated pipetting machine. After 48 h of incubation, tissue spheroids formed at the bottom of each microrecession. To assess the quality of constructs generated using this technology, 600 tissue spheroids made by this method were compared with 600 spheroids generated by the conventional hanging drop method. These analyses showed that tissue spheroids fabricated by the micromolded method are more uniform in diameter. Thus, use of micromolded recessions in a non-adhesive hydrogel, combined with automated cell seeding, is a reliable method for scalable robotic fabrication of uniform-sized tissue spheroids.

  7. Roles of dynamical symmetry breaking in driving oblate-prolate transitions of atomic clusters

    International Nuclear Information System (INIS)

    Oka, Yurie; Yanao, Tomohiro; Koon, Wang Sang

    2015-01-01

    This paper explores the driving mechanisms for structural transitions of atomic clusters between oblate and prolate isomers. We employ the hyperspherical coordinates to investigate structural dynamics of a seven-atom cluster at a coarse-grained level in terms of the dynamics of three gyration radii and three principal axes, which characterize overall mass distributions of the cluster. Dynamics of gyration radii is governed by two kinds of forces. One is the potential force originating from the interactions between atoms. The other is the dynamical forces called the internal centrifugal forces, which originate from twisting and shearing motions of the system. The internal centrifugal force arising from twisting motions has an effect of breaking the symmetry between two gyration radii. As a result, in an oblate isomer, activation of the internal centrifugal force that has the effect of breaking the symmetry between the two largest gyration radii is crucial in triggering structural transitions into prolate isomers. In a prolate isomer, on the other hand, activation of the internal centrifugal force that has the effect of breaking the symmetry between the two smallest gyration radii is crucial in triggering structural transitions into oblate isomers. Activation of a twisting motion that switches the movement patterns of three principal axes is also important for the onset of structural transitions between oblate and prolate isomers. Based on these trigger mechanisms, we finally show that selective activations of specific gyration radii and twisting motions, depending on the isomer of the cluster, can effectively induce structural transitions of the cluster. The results presented here could provide further insights into the control of molecular reactions

  8. Shell Venster

    International Nuclear Information System (INIS)

    De Wit, P.; Looijesteijn, B.; Regeer, B.; Stip, B.

    1995-03-01

    In the bi-monthly issues of 'Shell Venster' (window on Shell) attention is paid to the activities of the multinational petroleum company Shell Nederland and the Koninklijke/Shell Groep by means of non-specialist articles

  9. Modeling of optical absorption of silver prolate nanoparticles embedded in sol-gel glasses

    International Nuclear Information System (INIS)

    Renteria, V.M.; Garcia-Macedo, J.

    2005-01-01

    Silver prolate nanoparticles were obtained in silica gels prepared by the sol-gel process. Heating them at 900 deg. C for few minutes, the samples showed a yellow-orange color. A strong optical absorption with an asymmetric peak centred at 425 nm due to surface plasmon resonance of silver nanoparticles was observed. High-resolution transmission electron microscopy images showed silver prolate particles (average axial ratio AR = 0.76) randomly oriented with broad size distribution. The size changed from 9 to 3 nm and the prolate form changed to almost spherical (AR = 0.92) when the samples were heated longer time at 900 deg. C. In these samples, the absorption peak was shifted from 425 up to 460 nm. After heat treatment, the absorption spectrum did not change any more in some months, indicating that the particles obtained through this method are stable at room temperature. The Gans theory was used to fit the experimental spectra. The fit was not good until we assumed in the calculations all the physical features come from the system such as the volume fraction, shape and size of the metallic particles, and refractive index of the silica matrix. It was necessary to consider also a refractive index that come from oxidation on the surface of the metallic particles. With these considerations the fit with the Gans theory was good enough, and the difference between the calculated and experimental spectra was very small, factor 20 better than when oxidation is ignored. So then, the oxidation from the metallic particles must be taken in account to explain the experimental absorption spectra. These results are discussed

  10. Modeling of optical absorption of silver prolate nanoparticles embedded in sol-gel glasses

    Energy Technology Data Exchange (ETDEWEB)

    Renteria, V.M. [Departamento de Estado Solido, Instituto de Fisica, UNAM, P.O. Box 20-364, 01000 Mexico, Distrito Federal (Mexico); Garcia-Macedo, J. [Departamento de Estado Solido, Instituto de Fisica, UNAM, P.O. Box 20-364, 01000 Mexico, Distrito Federal (Mexico)]. E-mail: gamaj@fisica.unam.mx

    2005-05-15

    Silver prolate nanoparticles were obtained in silica gels prepared by the sol-gel process. Heating them at 900 deg. C for few minutes, the samples showed a yellow-orange color. A strong optical absorption with an asymmetric peak centred at 425 nm due to surface plasmon resonance of silver nanoparticles was observed. High-resolution transmission electron microscopy images showed silver prolate particles (average axial ratio AR = 0.76) randomly oriented with broad size distribution. The size changed from 9 to 3 nm and the prolate form changed to almost spherical (AR = 0.92) when the samples were heated longer time at 900 deg. C. In these samples, the absorption peak was shifted from 425 up to 460 nm. After heat treatment, the absorption spectrum did not change any more in some months, indicating that the particles obtained through this method are stable at room temperature. The Gans theory was used to fit the experimental spectra. The fit was not good until we assumed in the calculations all the physical features come from the system such as the volume fraction, shape and size of the metallic particles, and refractive index of the silica matrix. It was necessary to consider also a refractive index that come from oxidation on the surface of the metallic particles. With these considerations the fit with the Gans theory was good enough, and the difference between the calculated and experimental spectra was very small, factor 20 better than when oxidation is ignored. So then, the oxidation from the metallic particles must be taken in account to explain the experimental absorption spectra. These results are discussed.

  11. Solution of diffusion equation in deformable spheroids

    Energy Technology Data Exchange (ETDEWEB)

    Ayyoubzadeh, Seyed Mohsen [Department of Energy Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Safari, Mohammad Javad, E-mail: iFluka@gmail.com [Department of Energy Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Vosoughi, Naser [Department of Energy Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of)

    2011-05-15

    Research highlights: > Developing an explicit solution for the diffusion equation in spheroidal geometry. > Proving an orthogonality relation for spheroidal eigenfunctions. > Developing a relation for the extrapolation distance in spheroidal geometry. > Considering the sphere and slab as limiting cases for a spheroid. > Cross-validation of the analytical solution with Monte Carlo simulations. - Abstract: The time-dependent diffusion of neutrons in a spheroid as a function of the focal distance has been studied. The solution is based on an orthogonal basis and an extrapolation distanced related boundary condition for the spheroidal geometry. It has been shown that spheres and disks are two limiting cases for the spheroids, for which there is a smooth transition for the systems properties between these two limits. Furthermore, it is demonstrated that a slight deformation from a sphere does not affect the fundamental mode properties, to the first order. The calculations for both multiplying and non-multiplying media have been undertaken, showing good agreement with direct Monte Carlo simulations.

  12. Charged fluid distribution in higher dimensional spheroidal space-time

    Indian Academy of Sciences (India)

    associated 3-spaces obtained as hypersurfaces t = constant, 3-spheroids, are suit- ... pressure. Considering the Vaidya–Tikekar [12] spheroidal geometry, ... a relativistic star in hydrostatic equilibrium having the spheroidal geometry of the .... K = 1, the spheroidal 3-space degenerates into a flat 3-space and when K = 0 it.

  13. Proton radioactivity at non-collective prolate shape in high spin state of 94Ag

    International Nuclear Information System (INIS)

    Aggarwal, Mamta

    2010-01-01

    We predict proton radioactivity and structural transitions in high spin state of an excited exotic nucleus near proton drip line in a theoretical framework and investigate the nature and the consequences of the structural transitions on separation energy as a function of temperature and spin. It reveals that the rotation of the excited exotic nucleus 94 Ag at excitation energies around 6.7 MeV and angular momentum near 21h generates a rarely seen prolate non-collective shape and proton separation energy becomes negative which indicates proton radioactivity in agreement with the experimental results of Mukha et al. for 94 Ag.

  14. Proton radioactivity at non-collective prolate shape in high spin state of {sup 94}Ag

    Energy Technology Data Exchange (ETDEWEB)

    Aggarwal, Mamta, E-mail: mamta.a4@gmail.co [UM-DAE Centre for Excellence in Basic Sciences, University of Mumbai, Kalina Campus, Mumbai 400 098 (India)

    2010-10-11

    We predict proton radioactivity and structural transitions in high spin state of an excited exotic nucleus near proton drip line in a theoretical framework and investigate the nature and the consequences of the structural transitions on separation energy as a function of temperature and spin. It reveals that the rotation of the excited exotic nucleus {sup 94}Ag at excitation energies around 6.7 MeV and angular momentum near 21h generates a rarely seen prolate non-collective shape and proton separation energy becomes negative which indicates proton radioactivity in agreement with the experimental results of Mukha et al. for {sup 94}Ag.

  15. Nuclear masses, deformations and shell effects

    International Nuclear Information System (INIS)

    Hirsch, Jorge G; Barbero, César A; Mariano, Alejandro E

    2011-01-01

    We show that the Liquid Drop Model is best suited to describe the masses of prolate deformed nuclei than of spherical nuclei. To this end three Liquid Drop Mass formulas are employed to describe nuclear masses of eight sets of nuclei with similar quadrupole deformations. It is shown that they are able to fit the measured masses of prolate deformed nuclei with an RMS smaller than 750 keV, while for the spherical nuclei the RMS is, in the three cases, larger than 2000 keV. The RMS of the best fit of the masses of semi-magic nuclei is also larger than 2000 keV. The parameters of the three models are studied, showing that the surface symmetry term is the one which varies the most from one group of nuclei to another. In one model, isospin dependent terms are also found to exhibit strong changes. The inclusion of shell effects allows for better fits, which continue to be better in the prolate deformed nuclei region.

  16. Deformation and shell effects in nuclear mass formulas

    International Nuclear Information System (INIS)

    Barbero, César; Hirsch, Jorge G.; Mariano, Alejandro E.

    2012-01-01

    We analyze the ability of three different Liquid Drop Mass (LDM) formulas to describe nuclear masses for nuclei in various deformation regions. Separating the 2149 measured nuclear species into eight sets with similar quadrupole deformations, we show that the masses of prolate deformed nuclei are better described than those of spherical ones. In fact, the prolate deformed nuclei are fitted with an RMS smaller than 750 keV, while for spherical and semi-magic species the RMS is always larger than 2000 keV. These results are found to be independent of pairing. It is also shown that the macroscopic sector of the Duflo–Zuker (DZ) mass model reproduces shell effects, while most of the deformation dependence is lost and the RMS is larger than in any LDM. Adding to the LDM the microscopically motivated DZ master terms introduces the shell effects, allowing for a significant reduction in the RMS of the fit but still exhibiting a better description of prolate deformed nuclei. The inclusion of shell effects following the Interacting Boson Model's ideas produces similar results.

  17. Deformation and shell effects in nuclear mass formulas

    Energy Technology Data Exchange (ETDEWEB)

    Barbero, Cesar [Departamento de Fisica, Universidad Nacional de La Plata, C.C. 67, 1900 La Plata (Argentina); Instituto de Fisica La Plata, CONICET, 1900 La Plata (Argentina); Hirsch, Jorge G., E-mail: hirsch@nucleares.unam.mx [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, 04510 Mexico D.F. (Mexico); Mariano, Alejandro E. [Departamento de Fisica, Universidad Nacional de La Plata, C.C. 67, 1900 La Plata (Argentina); Instituto de Fisica La Plata, CONICET, 1900 La Plata (Argentina)

    2012-01-15

    We analyze the ability of three different Liquid Drop Mass (LDM) formulas to describe nuclear masses for nuclei in various deformation regions. Separating the 2149 measured nuclear species into eight sets with similar quadrupole deformations, we show that the masses of prolate deformed nuclei are better described than those of spherical ones. In fact, the prolate deformed nuclei are fitted with an RMS smaller than 750 keV, while for spherical and semi-magic species the RMS is always larger than 2000 keV. These results are found to be independent of pairing. It is also shown that the macroscopic sector of the Duflo-Zuker (DZ) mass model reproduces shell effects, while most of the deformation dependence is lost and the RMS is larger than in any LDM. Adding to the LDM the microscopically motivated DZ master terms introduces the shell effects, allowing for a significant reduction in the RMS of the fit but still exhibiting a better description of prolate deformed nuclei. The inclusion of shell effects following the Interacting Boson Model's ideas produces similar results.

  18. Bar-spheroid interaction in galaxies

    Science.gov (United States)

    Hernquist, Lars; Weinberg, Martin D.

    1992-01-01

    N-body simulation and linear analysis is employed to investigate the secular evolution of barred galaxies, with emphasis on the interaction between bars and spheroidal components of galaxies. This interaction is argued to drive secular transfer of angular momentum from bars to spheroids, primarily through resonant coupling. A moderately strong bar, having mass within corotation about 0.3 times the enclosed spheroid mass, is predicted to shed all its angular momentum typically in less than about 10 exp 9 yr. Even shorter depletion time scales are found for relatively more massive bars. It is suggested either that spheroids around barred galaxies are structured so as to inhibit strong coupling with bars, or that bars can form by unknown processes long after disks are established. The present models reinforce the notion that bars can drive secular evolution in galaxies.

  19. New directions at UNISOR and the importance of reinforcing spherical and deformed shell gaps

    International Nuclear Information System (INIS)

    Hamilton, J.H.

    1985-01-01

    An on-line nuclear orientation facility under construction for UNISOR is described. The strong competition between shell gaps at spherical, prolate and oblate deformation is shown to give rise to various structures from spherical double closed shell, to coexisting near-spherical and deformed shapes to deformed double closed shell nuclei in the region of A = 70-104. The importance of the reinforcing of the shape driving forces when the nucleus has shell gaps for the protons and neutrons at the same deformation on nuclear shapes and the switching of magic numbers is described

  20. Tidal disruption of dwarf spheroidal galaxies: the strange case of Crater II

    Science.gov (United States)

    Sanders, Jason L.; Evans, N. W.; Dehnen, W.

    2018-05-01

    Dwarf spheroidal galaxies of the Local Group obey a relationship between the line-of-sight velocity dispersion and half-light radius, although there are a number of dwarfs that lie beneath this relation with suppressed velocity dispersion. The most discrepant of these (in the Milky Way) is the `feeble giant' Crater II. Using analytic arguments supported by controlled numerical simulations of tidally-stripped flattened two-component dwarf galaxies, we investigate interpretations of Crater II within standard galaxy formation theory. Heavy tidal disruption is necessary to explain the velocity-dispersion suppression which is plausible if the proper motion of Crater II is (μα*, μδ) = ( - 0.21 ± 0.09, -0.24 ± 0.09)mas yr-1. Furthermore, we demonstrate that the velocity dispersion of tidally-disrupted systems is solely a function of the total mass loss even for weakly-embedded and flattened systems. The half-light radius evolution depends more sensitively on orbital phase and the properties of the dark matter profile. The half-light radius of weakly-embedded cusped systems rapidly decreases producing some tension with the Crater II observations. This tension is alleviated by cored dark matter profiles, in which the half-light radius can grow after tidal disruption. The evolution of flattened galaxies is characterised by two competing effects: tidal shocking makes the central regions rounder whilst tidal distortion produces a prolate tidally-locked outer envelope. After ˜70% of the central mass is lost, tidal distortion becomes the dominant effect and the shape of the central regions of the galaxy tends to a universal prolate shape irrespective of the initial shape.

  1. Plasma spheroidization and cladding of powders

    Energy Technology Data Exchange (ETDEWEB)

    Petrunichev, V.A.; Averin, V.V.; Sorokin, L.M.; Koroleva, E.B.

    1987-02-01

    With reference to experimental results for nickel and chromium alloys, it is shown that complex alloy powders can be spheroidized in plasma discharges using an argon plasma with hydrogen. The spheroidizing process is accompanied by the reduction of surface oxides, with uniform element distribution within the particles; the granulometric composition of the particles is preserved. It is also shown that plasma technology can be used for producing metal-clad oxide and carbide powders, which improve the performance of cermets and coatings.

  2. Unsuccessful mitosis in multicellular tumour spheroids.

    Science.gov (United States)

    Molla, Annie; Couvet, Morgane; Coll, Jean-Luc

    2017-04-25

    Multicellular spheroids are very attractive models in oncology because they mimic the 3D organization of the tumour cells with their microenvironment. We show here using 3 different cell types (mammary TSA/pc, embryonic kidney Hek293 and cervical cancer HeLa), that when the cells are growing as spheroids the frequency of binucleated cells is augmented as occurs in some human tumours.We therefore describe mitosis in multicellular spheroids by following mitotic markers and by time-lapse experiments. Chromosomes alignment appears to be correct on the metaphasic plate and the passenger complex is well localized on centromere. Moreover aurora kinases are fully active and histone H3 is phosphorylated on Ser 10. Consequently, the mitotic spindle checkpoint is satisfied and, anaphase proceeds as illustrated by the transfer of survivin on the spindle and by the segregation of the two lots of chromosomes. However, the segregation plane is not well defined and oscillations of the dividing cells are observed. Finally, cytokinesis fails and the absence of separation of the two daughter cells gives rise to binucleated cells.Division orientation is specified during interphase and persists throughout mitosis. Our data indicate that the cancer cells, in multicellular spheroids, lose their ability to regulate their orientation, a feature commonly encountered in tumours.Moreover, multicellular spheroid expansion is still sensitive to mitotic drugs as pactlitaxel and aurora kinase inhibitors. The spheroids thus represent a highly relevant model for studying drug efficiency in tumours.

  3. Repair during multifraction exposures: spheroids versus monolayers

    International Nuclear Information System (INIS)

    Durand, R.E.

    1984-01-01

    Many type of mammalian cells, when grown in culture as multicell spheroids, display an increased ability to accumulate and repair sublethal radiation damage which has been called the ''contact effect''. Since this effect has the potential to markedly modify the multifraction radiation response of cells in V79 spheroids relative to cells in monolayer cultures, an investigation was made of regimens ranging from 1 to 100 fractions. Effective dose rates were chosen near 1 Gy h -1 to inhibit cell progression and thus simplify analysis of the results. As expected, larger doses per fraction produced more net cell killing in both systems than lower doses per fraction. Additionally, less killing of spheroid cells was observed in all regimens, in accord with their greater potential for repair. However, when the data were expressed as isoeffect curves, the spheroid and monolayer curves converged as the number of fractions increased. Thus, quite similar inherent sensitivity and repair capabilities would be predicted for ultra-low doses per fraction. High precision techniques for defining survival after doses of radiation from 0.2 to 1 Gy were, however, still able to demonstrate a survival advantage for cells grown as spheroids. (author)

  4. Bistable flows in precessing spheroids

    Energy Technology Data Exchange (ETDEWEB)

    Cébron, D, E-mail: david.cebron@ujf-grenoble.fr [Université Grenoble Alpes, CNRS, ISTerre, Grenoble (France)

    2015-04-15

    Precession driven flows are found in any rotating container filled with liquid, when the rotation axis itself rotates about a secondary axis that is fixed in an inertial frame of reference. Because of its relevance for planetary fluid layers, many works consider spheroidal containers, where the uniform vorticity component of the bulk flow is reliably given by the well-known equations obtained by Busse (1968 J. Fluid Mech. 33 739–51). So far however, no analytical result for the solutions is available. Moreover, the cases where multiple flows can coexist have not been investigated in detail since their discovery by Noir et al (2003 Geophys. J. Int. 154 407–16). In this work we aim at deriving analytical results for the solutions, aiming in particular at first estimating the ranges of parameters where multiple solutions exist, and second studying quantitatively their stability. Using the models recently proposed by Noir and Cébron (2013 J. Fluid Mech. 737 412–39), which are more generic in the inviscid limit than the equations of Busse, we analytically describe these solutions, their conditions of existence, and their stability in a systematic manner. We then successfully compare these analytical results with the theory of Busse (1968). Dynamical model equations are finally proposed to investigate the stability of the solutions, which describe the bifurcation of the unstable flow solution. We also report for the first time the possibility that time-dependent multiple flows can coexist in precessing triaxial ellipsoids. Numerical integrations of the algebraic and differential equations have been efficiently performed with the dedicated script FLIPPER (supplementary material). (paper)

  5. Nuclear ground state properties and self-consistent calculations with the Skyrme interaction. II. S-D shell nuclei

    International Nuclear Information System (INIS)

    Flocard, H.

    1975-04-01

    Hartree-Fock results concerning the ground state properties of some S-D shell nuclei are discussed. Two different Skyrme interactions have been used. They both lead to good agreement with the experimental total binding energies, charge radii and multipole moments. In particular the observed prolate-oblate transitions occuring in the S-D shell are reproduced. The calculated spectroscopic factors are also shown to be consistent with experimental data [fr

  6. THE STELLAR STRUCTURE AND KINEMATICS OF DWARF SPHEROIDAL GALAXIES FORMED BY TIDAL STIRRING

    International Nuclear Information System (INIS)

    Lokas, Ewa L.; Klimentowski, Jaroslaw; Kazantzidis, Stelios; Mayer, Lucio; Callegari, Simone

    2010-01-01

    Using high-resolution N-body simulations, we study the stellar properties of dwarf spheroidal (dSph) galaxies resulting from the tidally induced morphological transformation of disky dwarfs on a cosmologically motivated eccentric orbit around the Milky Way. The dwarf galaxy models initially consist of an exponential stellar disk embedded in an extended spherical dark matter halo. Depending on the initial orientation of the disk with respect to the orbital plane, different final configurations are obtained. The least evolved dwarf is triaxial and retains a significant amount of rotation. The more evolved dwarfs are prolate spheroids with little rotation. We show that in this scenario the final density distribution of stars can be approximated by a simple modification of the Plummer law. The kinematics of the dwarfs is significantly different depending on the line of sight which has important implications for mapping the observed stellar velocity dispersions of dwarfs to subhalo circular velocities. When the dwarfs are observed along the long axis, the measured velocity dispersion is higher and decreases faster with radius. In the case where rotation is significant, when viewed perpendicular to the long axis, the effect of minor axis rotation is detected, as expected for triaxial systems. We model the velocity dispersion profiles and rotation curves of the dwarfs under the assumption of constant mass-to-light ratio by solving the Jeans equations for spherical and axisymmetric systems and adjusting different sets of free parameters, including the total mass. We find that the mass is typically overestimated when the dwarf is seen along the long axis and underestimated when the observation is along the short or intermediate axis. For the studied cases, the effect of non-sphericity cannot, however, bias the inferred mass by more than 60% in either direction, even for the most strongly stripped dwarf which is close to disruption.

  7. Misorientations in spheroidal graphite: some new insights about spheroidal graphite growth in cast irons

    International Nuclear Information System (INIS)

    Lacaze, J; Theuwissen, K; Laffont, L; Véron, M

    2016-01-01

    Local diffraction patterning, orientation mapping and high resolution transmission electron microscopy imaging have been used to characterize misorientations in graphite spheroids of cast irons. Emphasis is put here on bulk graphite, away from the nucleus as well as from the outer surface of the spheroids in order to get information on their growth during solidification. The results show that spheroidal graphite consists in conical sectors made of elementary blocks piled up on each other. These blocks are elongated along the prismatic a direction of graphite with the c axes roughly parallel to the radius of the spheroids. This implies that the orientation of the blocks rotates around the spheroid centre giving low angle tilting misorientations along tangential direction within each sector. Misorientations between neighbouring sectors are of higher values and their interfaces show rippled layers which are characteristic of defects in graphene. Along a radius of the spheroid, clockwise and anticlockwise twisting between blocks is observed. These observations help challenging some of the models proposed to explain spheroidal growth in cast ions. (paper)

  8. Charged fluid distribution in higher dimensional spheroidal space-time

    Indian Academy of Sciences (India)

    A general solution of Einstein field equations corresponding to a charged fluid distribution on the background of higher dimensional spheroidal space-time is obtained. The solution generates several known solutions for superdense star having spheroidal space-time geometry.

  9. Dwarf spheroidal galaxies: Keystones of galaxy evolution

    Science.gov (United States)

    Gallagher, John S., III; Wyse, Rosemary F. G.

    1994-01-01

    Dwarf spheroidal galaxies are the most insignificant extragalactic stellar systems in terms of their visibility, but potentially very significant in terms of their role in the formation and evolution of much more luminous galaxies. We discuss the present observational data and their implications for theories of the formation and evolution of both dwarf and giant galaxies. The putative dark-matter content of these low-surface-brightness systems is of particular interest, as is their chemical evolution. Surveys for new dwarf spheroidals hidden behind the stars of our Galaxy and those which are not bound to giant galaxies may give new clues as to the origins of this unique class of galaxy.

  10. Differential thermo-resistance of multicellular tumor spheroids

    International Nuclear Information System (INIS)

    Khoei, S.; Goliaei, B.; Neshasteh-Rize, A.

    2004-01-01

    Many cell lines, when cultured under proper conditions, can form three dimensional structures called multicellular spheroids. These spheroids resemble in vivo tumor models in several aspects. Therefore, studying growth characteristics and behavior of spheroids is beneficial in understanding the behavior of tumors under various experimental conditions. In this work, we have studied the growth properties, along with the thermal characteristics of spheroids of Du 145 human prostate carcinoma cell lines and compared the results to monolayer cultures of these cells. For this purpose, The Du 145 cells were cultured either as monolayer or spheroids. At various times after initiation of cultures, the growth properties of spheroids as a function of seeding cell number was determined. To evaluate the thermal characteristics of spheroids, they were heated at various stages of growth at 43 d ig c for various periods. The thermal response was judged by the survival fraction of colony forming cells in spheroids or monolayer culture following heat treatment. The results showed spheroids were more resistant to heat than monolayer cultures at all stages of development. However, the extent of this thermal resistant was dependent on the age, and consequently, the size of the spheroid. The result suggests that the differential thermal resistance of the spheroid cultures develop gradually during the growth of spheroid cultures of Du 145 cell line

  11. Partial discharges in spheroidal voids: Void orientation

    DEFF Research Database (Denmark)

    McAllister, Iain Wilson

    1997-01-01

    Partial discharge transients can be described in terms of the charge induced on the detecting electrode. The influence of the void parameters upon the induced charge is examined and discussed for spheroidal voids. It is shown that a quantitative interpretation of the induced charge requires...

  12. Zero-point energy in spheroidal geometries

    OpenAIRE

    Kitson, A. R.; Signal, A. I.

    2005-01-01

    We study the zero-point energy of a massless scalar field subject to spheroidal boundary conditions. Using the zeta-function method, the zero-point energy is evaluated for small ellipticity. Axially symmetric vector fields are also considered. The results are interpreted within the context of QCD flux tubes and the MIT bag model.

  13. Convection in Slab and Spheroidal Geometries

    Science.gov (United States)

    Porter, David H.; Woodward, Paul R.; Jacobs, Michael L.

    2000-01-01

    Three-dimensional numerical simulations of compressible turbulent thermally driven convection, in both slab and spheroidal geometries, are reviewed and analyzed in terms of velocity spectra and mixing-length theory. The same ideal gas model is used in both geometries, and resulting flows are compared. The piecewise-parabolic method (PPM), with either thermal conductivity or photospheric boundary conditions, is used to solve the fluid equations of motion. Fluid motions in both geometries exhibit a Kolmogorov-like k(sup -5/3) range in their velocity spectra. The longest wavelength modes are energetically dominant in both geometries, typically leading to one convection cell dominating the flow. In spheroidal geometry, a dipolar flow dominates the largest scale convective motions. Downflows are intensely turbulent and up drafts are relatively laminar in both geometries. In slab geometry, correlations between temperature and velocity fluctuations, which lead to the enthalpy flux, are fairly independent of depth. In spheroidal geometry this same correlation increases linearly with radius over the inner 70 percent by radius, in which the local pressure scale heights are a sizable fraction of the radius. The effects from the impenetrable boundary conditions in the slab geometry models are confused with the effects from non-local convection. In spheroidal geometry nonlocal effects, due to coherent plumes, are seen as far as several pressure scale heights from the lower boundary and are clearly distinguishable from boundary effects.

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

    Directory of Open Access Journals (Sweden)

    A. G. Magner

    2010-09-01

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

  15. Application of the adiabatic self-consistent collective coordinate method to a solvable model of prolate-oblate shape coexistence

    International Nuclear Information System (INIS)

    Kobayasi, Masato; Matsuyanagi, Kenichi; Nakatsukasa, Takashi; Matsuo, Masayuki

    2003-01-01

    The adiabatic self-consistent collective coordinate method is applied to an exactly solvable multi-O(4) model that is designed to describe nuclear shape coexistence phenomena. The collective mass and dynamics of large amplitude collective motion in this model system are analyzed, and it is shown that the method yields a faithful description of tunneling motion through a barrier between the prolate and oblate local minima in the collective potential. The emergence of the doublet pattern is clearly described. (author)

  16. Design of a uranium-dioxide powder spheroidization system by plasma processing

    Science.gov (United States)

    Cavender, Daniel

    The plasma spheroidization system (PSS) is the first process in the development of a tungsten-uranium dioxide (W-UO2) ceramic-metallic (cermet) fuel for nuclear thermal rocket (NTR) propulsion. For the purposes of fissile fuel retention, UO2 spheroids ranging in size from 50 - 100 micrometers (μm) in diameter will be encapsulated in a tungsten shell. The PSS produces spherical particles by melting angular stock particles in an argon-hydrogen plasma jet where they become spherical due to surface tension. Surrogate CeO 2 powder was used in place of UO2 for system and process parameter development. Stock and spheroidized powders were micrographed using optical and scanning electron microscopy and evaluated by statistical methods to characterize and compare the spherocity of pre and post process powders. Particle spherocity was determined by irregularity parameter. Processed powders showed a statistically significant improvement in spherocity, with greater that 60% of the examined particles having an irregularity parameter of equal to or lower than 1.2, compared to stock powder.

  17. Mass Spectrometry Analyses of Multicellular Tumor Spheroids.

    Science.gov (United States)

    Acland, Mitchell; Mittal, Parul; Lokman, Noor A; Klingler-Hoffmann, Manuela; Oehler, Martin K; Hoffmann, Peter

    2018-05-01

    Multicellular tumor spheroids (MCTS) are a powerful biological in vitro model, which closely mimics the 3D structure of primary avascularized tumors. Mass spectrometry (MS) has established itself as a powerful analytical tool, not only to better understand and describe the complex structure of MCTS, but also to monitor their response to cancer therapeutics. The first part of this review focuses on traditional mass spectrometry approaches with an emphasis on elucidating the molecular characteristics of these structures. Then the mass spectrometry imaging (MSI) approaches used to obtain spatially defined information from MCTS is described. Finally the analysis of primary spheroids, such as those present in ovarian cancer, and the great potential that mass spectrometry analysis of these structures has for improved understanding of cancer progression and for personalized in vitro therapeutic testing is discussed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Axisymmetric Eigenmodes of Spheroidal Pure Electron Plasmas

    Science.gov (United States)

    Kawai, Yosuke; Saitoh, Haruhiko; Yoshida, Zensho; Kiwamoto, Yasuhito

    2010-11-01

    The axisymmetric electrostatic eigenmodes of spheroidal pure electron plasmas have been studied experimentally. It is confirmed that the observed spheroidal plasma attains a theoretically expected equilibrium density distribution, with the exception of a low-density halo distribution surrounding the plasma. When the eigenmode frequency observed for the plasma is compared with the frequency predicted by the dispersion relation derived under ideal conditions wherein the temperature is zero and the boundary is located at an infinite distance from the plasma, it is observed that the absolute value of the observed frequency is systematically higher than the theoretical prediction. Experimental examinations and numerical calculations indicate that the upward shift of the eigenmode frequency cannot be accounted for solely by the finite temperature effect, but is significantly affected by image charges induced on the conducting boundary and the resulting distortion of the density profile from the theoretical expectation.

  19. Non-existence of separable spheroidal beams

    International Nuclear Information System (INIS)

    Boyack, Rufus; Lekner, John

    2011-01-01

    We show that ψ = R(ξ)S(η) e imφ , a product of radial and angular oblate spheroidal functions and an azimuthal factor, cannot represent physical free-space scalar beams. The reason lies in the discontinuity in the longitudinal derivative of ψ in the focal plane, where ψ is not a solution of the Helmholtz equation on the disc ξ = 0

  20. Morphological and Immunohistochemical Characterization of Canine Osteosarcoma Spheroid Cell Cultures.

    Science.gov (United States)

    Gebhard, C; Gabriel, C; Walter, I

    2016-06-01

    Spheroid cell culture emerges as powerful in vitro tool for experimental tumour research. In this study, we established a scaffold-free three-dimensional spheroid system built from canine osteosarcoma (OS) cells (D17). Spheroids (7, 14 and 19 days of cultivation) and monolayer cultures (2 and 7 days of cultivation) were evaluated and compared on light and electron microscopy. Monolayer and spheroid cultures were tested for vimentin, cytokeratin, alkaline phosphatase, osteocalcin and collagen I by means of immunohistochemistry. The spheroid cell culture exhibited a distinct network of collagen I in particular after 19-day cultivation, whereas in monolayer cultures, collagen I was arranged as a lamellar basal structure. Necrotic centres of large spheroids, as observed in 14- and 19-day cultures, were characterized by significant amounts of osteocalcin. Proliferative activity as determined by Ki-67 immunoreactivity showed an even distribution in two-dimensional cultures. In spheroids, proliferation was predominating in the peripheral areas. Metastasis-associated markers ezrin and S100A4 were shown to be continuously expressed in monolayer and spheroid cultures. We conclude that the scaffold-free spheroid system from canine OS cells has the ability to mimic the architecture of the in vivo tumour, in particular cell-cell and cell-matrix interactions. © 2015 The Authors. Anatomia, Histologia, Embryologia Published by Blackwell Verlag GmbH.

  1. Global Landslides on Rapidly Spinning Spheroids

    Science.gov (United States)

    Scheeres, Daniel J.; Sanchez, P.

    2013-10-01

    The angle of repose and conditions for global landslides on the surfaces of small, rapidly spinning, spheroidal asteroids are studied. Applying techniques of soil mechanics, we develop a theory for, and examples of, how regolith will fail and flow in this microgravity environment. Our motivation is to develop an understanding of the "top-shaped" class of asteroids based on analytical soil mechanics. Our analysis transforms the entire asteroid surface into a local frame where we can model it as a conventional granular pile with a surface slope, acceleration and height variations as a function of the body's spin rate, shape and density. A general finding is that the lowest point on a rapidly spinning spheroid is at the equator with the effective height of surface material monotonically increasing towards the polar regions, where the height can be larger than the physical radius of the body. We study the failure conditions of both cohesionless and cohesive regolith, and develop specific predictions of the surface profile as a function of the regolith angle of friction and the maximum spin rate experienced by the body. The theory also provides simple guidelines on what the shape may look like, although we do not analyze gravitationally self-consistent evolution of the body shape. The theory is tested with soft-sphere discrete element method granular mechanics simulations to better understand the dynamical aspects of global asteroid landslides. We find significant differences between failure conditions for cohesive and cohesionless regolith. In the case of cohesive regolith, we show that extremely small values of strength (much less than that found in lunar regolith) can stabilize a surface even at very rapid spin rates. Cohesionless surfaces, as expected, fail whenever their surface slopes exceed the angle of friction. Based on our analysis we propose that global landslides and the flow of material towards the equator on spheroidal bodies are precipitated by exogenous

  2. On realistic size equivalence and shape of spheroidal Saharan mineral dust particles applied in solar and thermal radiative transfer calculations

    Directory of Open Access Journals (Sweden)

    S. Otto

    2011-05-01

    Full Text Available Realistic size equivalence and shape of Saharan mineral dust particles are derived from in-situ particle, lidar and sun photometer measurements during SAMUM-1 in Morocco (19 May 2006, dealing with measured size- and altitude-resolved axis ratio distributions of assumed spheroidal model particles. The data were applied in optical property, radiative effect, forcing and heating effect simulations to quantify the realistic impact of particle non-sphericity. It turned out that volume-to-surface equivalent spheroids with prolate shape are most realistic: particle non-sphericity only slightly affects single scattering albedo and asymmetry parameter but may enhance extinction coefficient by up to 10 %. At the bottom of the atmosphere (BOA the Saharan mineral dust always leads to a loss of solar radiation, while the sign of the forcing at the top of the atmosphere (TOA depends on surface albedo: solar cooling/warming over a mean ocean/land surface. In the thermal spectral range the dust inhibits the emission of radiation to space and warms the BOA. The most realistic case of particle non-sphericity causes changes of total (solar plus thermal forcing by 55/5 % at the TOA over ocean/land and 15 % at the BOA over both land and ocean and enhances total radiative heating within the dust plume by up to 20 %. Large dust particles significantly contribute to all the radiative effects reported. They strongly enhance the absorbing properties and forward scattering in the solar and increase predominantly, e.g., the total TOA forcing of the dust over land.

  3. Structure of the Draco Dwarf Spheroidal Galaxy

    OpenAIRE

    Piatek, Slawomir; Pryor, Carlton; Armandroff, Taft E.; Olszewski, Edward W.

    2002-01-01

    This article studies the structure of the Draco dwarf spheroidal galaxy with an emphasis on the question of whether the spatial distribution of its stars has been affected by the tidal interaction with the Milky Way, using R- and V-band CCD photometry for eleven fields. The article reports coordinates for the center, a position angle of the major axis, and the ellipticity. It also reports the results of searches for asymmetries in the structure of Draco. These results, and searches for a ``br...

  4. Process for producing uranium carbide spheroids

    International Nuclear Information System (INIS)

    Shennan, J.V.; Ford, L.H.

    1977-01-01

    The invention deals with a method to fabricate UC spheroids which are filled into moulds made of refractory material for fuel elements. The UC fuel particles are double-coated: a first thin layer of pyrolytic carbon is coated at low temperature 1200-1400 0 C, a record layer of pyrolytic material (e.g. Si c) is coated at a higher temperature (above 1500 0 C) which holds back the fission products. The method is described more closely by means of an example. (GSC) [de

  5. Process for producing uranium carbide spheroids

    International Nuclear Information System (INIS)

    Shennan, J.V.; Ford, L.H.

    1976-01-01

    The invention deals with a method to produce UC spheroids which are filled into molded bodies of fire-proof material for fuel elements. The UC fuel particles are doubly coated: a first thin layer of pyrolytic carbon is coated at low temperature (1,200-1,400 0 C), a second layer of fire-proof material (e.g. SiC) is coated at a higher temperature (above 1,500 0 C) which holds back the fission products. The process is explained in more detail using an example. (GSCH) [de

  6. Digital microfluidics for automated hanging drop cell spheroid culture.

    Science.gov (United States)

    Aijian, Andrew P; Garrell, Robin L

    2015-06-01

    Cell spheroids are multicellular aggregates, grown in vitro, that mimic the three-dimensional morphology of physiological tissues. Although there are numerous benefits to using spheroids in cell-based assays, the adoption of spheroids in routine biomedical research has been limited, in part, by the tedious workflow associated with spheroid formation and analysis. Here we describe a digital microfluidic platform that has been developed to automate liquid-handling protocols for the formation, maintenance, and analysis of multicellular spheroids in hanging drop culture. We show that droplets of liquid can be added to and extracted from through-holes, or "wells," and fabricated in the bottom plate of a digital microfluidic device, enabling the formation and assaying of hanging drops. Using this digital microfluidic platform, spheroids of mouse mesenchymal stem cells were formed and maintained in situ for 72 h, exhibiting good viability (>90%) and size uniformity (% coefficient of variation <10% intraexperiment, <20% interexperiment). A proof-of-principle drug screen was performed on human colorectal adenocarcinoma spheroids to demonstrate the ability to recapitulate physiologically relevant phenomena such as insulin-induced drug resistance. With automatable and flexible liquid handling, and a wide range of in situ sample preparation and analysis capabilities, the digital microfluidic platform provides a viable tool for automating cell spheroid culture and analysis. © 2014 Society for Laboratory Automation and Screening.

  7. Multicellular spheroids as an in vitro tumor model

    International Nuclear Information System (INIS)

    Kozubek, S.; Erzgraber, G.

    1982-01-01

    Experiments with fractionated irradiation of multicellular spheroids were performed. Our data as well as the data of other works have been evaluated by means of simple mathematical formulae on the basis of several hypothesis. The spheroids are shown to exhibit similar behaviour as in vivo carcinomas. They offer the possibility of investigation of quantitative correlations for practical purposes

  8. Short-term effects of radiation in gliolalstoma spheroids

    DEFF Research Database (Denmark)

    Petterson, Stine Asferg; Jakobsen, Ida Pind; Jensen, Stine Skov

    2016-01-01

    was to investigate the short-term effects of radiation of spheroids containing tumor-initiating stem-like cells. We used a patient-derived glioblastoma stem cell enriched culture (T76) and the standard glioblastoma cell line U87. Primary spheroids were irradiated with doses between 2 and 50 Gy and assessed after two...

  9. Variable Stars in the M31 Dwarf Spheroidal Companion Cassiopeia

    Science.gov (United States)

    Pritzl, Barton J.; Armandroff, T. E.; Jacoby, G. H.; Da Costa, G. S.

    2007-12-01

    Dwarf spheroidal galaxies show very diverse star formation histories. For the Galactic dwarf spheroidal galaxies, a correlation exists between Galactocentric distance and the prominence of intermediate-age ( 2 - 10 Gyr) populations. To test whether this correlation exists for the M31 dwarf spheroidal galaxies, we observed the Cassiopeia (And VII) dwarf galaxy, which is one of the most distant M31 dwarf spheroidal galaxies. We will present the results of a variable star search using HST/ACS data, along with a preliminary color-magnitude diagram. From the RR Lyrae stars we can obtain an independent distance and metallicity estimate for the dwarf galaxy. These results will be compared to those found for the other M31 dwarf spheroidal galaxies.This research is supported in part by NASA through grant number GO-11081.11 from the Space Telescope Science Institute.

  10. Development of controlled release spheroids using Buchananiacochinchinesis gum

    Directory of Open Access Journals (Sweden)

    Narayan Babulal Gaikwad

    2013-03-01

    Full Text Available Chirauli nut gum was isolated from the bark of Buchanania cochinchinesis (fam. Anacadiacea and was used as a release modifier for the preparation of Diclofenac sodium spheroids using the extrusion spheronization technique. The process was studied for the effects on variables when making spheroids with satisfactory particle shape, size and size distribution. The prepared spheroids were characterized for surface morphology, qualitative surface porosity, friability, bulk density and flow properties. In vitro studies demonstrated that the release exhibited Fickian diffusion kinetics which was confirmed by the Higuchi and the Korsmeyer-Peppas models. The physico-chemical parameters of the gum could be correlated to the in vitro dissolution profile of the spheroids. The spheroids were not able to sustain the drug releases over 12 hours. A greater concentration of Chirauli nut gum and a process that can accommodate such greater concentrations may produce a formulation capable of significant sustained release.

  11. Design of a Uranium Dioxide Spheroidization System

    Science.gov (United States)

    Cavender, Daniel P.; Mireles, Omar R.; Frendi, Abdelkader

    2013-01-01

    The plasma spheroidization system (PSS) is the first process in the development of tungsten-uranium dioxide (W-UO2) fuel cermets. The PSS process improves particle spherocity and surface morphology for coating by chemical vapor deposition (CVD) process. Angular fully dense particles melt in an argon-hydrogen plasma jet at between 32-36 kW, and become spherical due to surface tension. Surrogate CeO2 powder was used in place of UO2 for system and process parameter development. Particles range in size from 100 - 50 microns in diameter. Student s t-test and hypothesis testing of two proportions statistical methods were applied to characterize and compare the spherocity of pre and post process powders. Particle spherocity was determined by irregularity parameter. Processed powders show great than 800% increase in the number of spherical particles over the stock powder with the mean spherocity only mildly improved. It is recommended that powders be processed two-three times in order to reach the desired spherocity, and that process parameters be optimized for a more narrow particles size range. Keywords: spherocity, spheroidization, plasma, uranium-dioxide, cermet, nuclear, propulsion

  12. Shell supports

    DEFF Research Database (Denmark)

    Almegaard, Henrik

    2004-01-01

    A new statical and conceptual model for membrane shell structures - the stringer system - has been found. The principle was first published at the IASS conference in Copenhagen (OHL91), and later the theory has been further developed (ALMO3)(ALMO4). From the analysis of the stringer model it can...... be concluded that all membrane shells can be described by a limited number of basic configurations of which quite a few have free edges....

  13. Differentiation of human mesenchymal stem cell spheroids under microgravity conditions

    Directory of Open Access Journals (Sweden)

    Wolfgang H Cerwinka

    2012-01-01

    Full Text Available To develop and characterize a novel cell culture method for the generation of undifferentiated and differentiated human mesenchymal stem cell 3D structures, we utilized the RWV system with a gelatin-based scaffold. 3 × 106 cells generated homogeneous spheroids and maximum spheroid loading was accomplished after 3 days of culture. Spheroids cultured in undifferentiated spheroids of 3 and 10 days retained expression of CD44, without expression of differentiation markers. Spheroids cultured in adipogenic and osteogenic differentiation media exhibited oil red O staining and von Kossa staining, respectively. Further characterization of osteogenic lineage, showed that 10 day spheroids exhibited stronger calcification than any other experimental group corresponding with significant expression of vitamin D receptor, alkaline phosphatase, and ERp60 . In conclusion this study describes a novel RWV culture method that allowed efficacious engineering of undifferentiated human mesenchymal stem cell spheroids and rapid osteogenic differentiation. The use of gelatin scaffolds holds promise to design implantable stem cell tissue of various sizes and shapes for future regenerative treatment.

  14. Ellipticity behaviour of relativistic Maclaurin spheroids

    International Nuclear Information System (INIS)

    Abramowicz, M.A.; Miller, J.C.; International School of Advanced Studies, Trieste; Oxford Univ.

    1990-01-01

    Chandrasekhar and Miller (1974 Mon. Not. R. Astr. Soc., 167, 63) found that, according to the general theory of relativity, when slowly rotating spheroids contract, conserving angular momentum, their eccentricity does not increase monotonically, as is the case for Newtonian gravity, but instead reaches a maximum (when the mean radius is a few times the Schwarzschild radius) and then decreases again. We show here that this can be explained within the framework of the recent discussion of rotational effects in a strong gravitational field. We suggest that it can be convenient to introduce a 'corrected' Newtonian theory, incorporating terms to approximate strong field effects, and that such a corrected theory could be useful for numerical studies. (author)

  15. Electron, proton, neutron as spheroidical particles

    International Nuclear Information System (INIS)

    Bagge, E.R.

    1993-01-01

    It is shown that it is possible to describe the electron and the proton at rest within the framework of Dirac's relativistic theory of particles as electro-magnetic stable, spheroidal particles like balloons with very thin envelopes. Their properties, especially their spins and their magnetic momenta, are exactly those, which have been measured at first and later on derived by Dirac. In this picture the neutron plays the role of a system of two concentric and synchronically rotating balloons with a small distance between them at a positive energetic minimum of balance at 1.26 MeV. The magnetic moment of this particle has a negative sign and is of the correct size. (orig.)

  16. Plasma spheroidizing and cladding of powders

    International Nuclear Information System (INIS)

    Petrunichev, V.A.; Averin, V.V.; Sorokin, L.M.; Koroleva, E.B.

    1987-01-01

    Arc and high-frequency plasmatrons are used for spheroidizing nickel and chromium-base alloy particles. Different plasma-forming medium compositions are used in the arc variant and the effect of these media on the plasma treatment product is demonstrated. For a high-frequency plasmatron, a long time of plasma contact with the powder leads to the transfer of the part of the material from the treated particles into vaporous state with subsequent condensation at the outlet from the discharge zone. Results of investigations into the formation of metal coatings on oxide and carbide particles during plasma-arc action are also presented. Representative data on the output of particles with coating are obtained and factors, providing for the optimal particle cladding conditions, are indicated

  17. [Reparative and neoplastic spheroid cellular structures and their mathematical model].

    Science.gov (United States)

    Kogan, E A; Namiot, V A; Demura, T A; Faĭzullina, N M; Sukhikh, G T

    2014-01-01

    Spheroid cell structures in the cell cultures have been described and are used for studying cell-cell and cell- matrix interactions. At the same time, spheroid cell structure participation in the repair and development of cancer in vivo remains unexplored. The aim of this study was to investigate the cellular composition of spherical structures and their functional significance in the repair of squamous epithelium in human papilloma virus-associated cervical pathology--chronic cervicitis and cervical intraepithelial neoplasia 1-3 degree, and also construct a mathematical model to explain the development and behavior of such spheroid cell structure.

  18. Collective motion in prolate γ-rigid nuclei within minimal length concept via a quantum perturbation method

    Science.gov (United States)

    Chabab, M.; El Batoul, A.; Lahbas, A.; Oulne, M.

    2018-05-01

    Based on the minimal length concept, inspired by Heisenberg algebra, a closed analytical formula is derived for the energy spectrum of the prolate γ-rigid Bohr-Mottelson Hamiltonian of nuclei, within a quantum perturbation method (QPM), by considering a scaled Davidson potential in β shape variable. In the resulting solution, called X(3)-D-ML, the ground state and the first β-band are all studied as a function of the free parameters. The fact of introducing the minimal length concept with a QPM makes the model very flexible and a powerful approach to describe nuclear collective excitations of a variety of vibrational-like nuclei. The introduction of scaling parameters in the Davidson potential enables us to get a physical minimum of this latter in comparison with previous works. The analysis of the corrected wave function, as well as the probability density distribution, shows that the minimal length parameter has a physical upper bound limit.

  19. Powder processing and spheroidizing with thermal inductively coupled plasma

    International Nuclear Information System (INIS)

    Nutsch, G.; Linke, P.; Zakharian, S.; Dzur, B.; Weiss, K.-H.

    2001-01-01

    Processing of advanced powder materials for the spraying industry is one of the most promising applications of the thermal RF inductively coupled plasma. By selecting the feedstock carefully and adjusting the RF plasma parameters, unique materials with high quality can be achieved. Powders injected in the hot plasma core emerge with modified shapes, morphology, crystal structure and chemical composition. Ceramic oxide powders such as Al 2 O 3 , ZrO 2 , SiO 2 are spheroidized with a high spheroidization rate. By using the RF induction plasma spheroidizing process tungsten melt carbide powders are obtained with a high spheroidization rate at high feeding rates by densification of agglomerated powders consisting of di-tungsten carbide and monocarbide with a definite composition. This kind of ball-like powders is particularly suited for wear resistant applications. (author)

  20. Spheroidization of transition metal carbides in low temperature plasma

    International Nuclear Information System (INIS)

    Klinskaya, N.A.; Koroleva, E.B.; Petrunichev, V.A.; Rybalko, O.F.; Solov'ev, P.V.; Ugol'nikova, T.A.

    1986-01-01

    Plasma process of preparation of titanium, tungsten and chromium carbide spherical powders with the main particle size 40-80 μm is considered. Spheroidization degree, granulometric and phase composition of the product are investigated

  1. Dwarf Spheroidal Satellite Formation in a Reionized Local Group

    OpenAIRE

    Milosavljevic, Milos; Bromm, Volker

    2013-01-01

    Dwarf spheroidal satellite galaxies have emerged a powerful probe of small-scale dark matter clustering and of cosmic reionization. They exhibit structural and chemical continuity with dwarf irregular galaxies in the field and with spheroidal galaxies in high-density environments. By combining empirical constraints derived for star formation at low gas column densities and metallicities in the local universe with a model for dark matter and baryonic mass assembly, we provide an analytical des...

  2. Shell Model Far From Stability: Island of Inversion Mergers

    Science.gov (United States)

    Nowacki, F.; Poves, A.

    2018-02-01

    In this study we propose a common mechanism for the disappearance of shell closures far from stabilty. With the use of Large Scale Shell Model calculations (SM-CI), we predict that the region of deformation which comprises the heaviest Chromium and Iron isotopes at and beyond N=40 will merge with a new one at N=50 in an astonishing parallel to the N=20 and N=28 case in the Neon and Magnesium isotopes. We propose a valence space including the full pf-shell for the protons and the full sdg shell for the neutrons, which represents a come-back of the the harmonic oscillator shells in the very neutron rich regime. Our calculations preserve the doubly magic nature of the ground state of 78Ni, which, however, exhibits a well deformed prolate band at low excitation energy, providing a striking example of shape coexistence far from stability. This new Island of Inversion (IoI) adds to the four well documented ones at N=8, 20, 28 and 40.

  3. Self-assembly of tissue spheroids on polymeric membranes.

    Science.gov (United States)

    Messina, Antonietta; Morelli, Sabrina; Forgacs, Gabor; Barbieri, Giuseppe; Drioli, Enrico; De Bartolo, Loredana

    2017-07-01

    In this study, multicellular tissue spheroids were fabricated on polymeric membranes in order to accelerate the fusion process and tissue formation. To this purpose, tissue spheroids composed of three different cell types, myoblasts, fibroblasts and neural cells, were formed and cultured on agarose and membranes of polycaprolactone (PCL) and chitosan (CHT). Membranes prepared by a phase-inversion technique display different physicochemical, mechanical and transport properties, which can affect the fusion process. The membranes accelerated the fusion process of a pair of spheroids with respect to the inert substrate. In this process, a critical role is played by the membrane properties, especially by their mechanical characteristics and oxygen and carbon dioxide mass transfer. The rate of fusion was quantified and found to be similar for fibroblast, myoblast and neural tissue spheroids on membranes, which completed the fusion within 3 days. These spheroids underwent faster fusion and maturation on PCL membrane than on agarose, the rate of fusion being proportional to the value of oxygen and carbon dioxide permeances and elastic characteristics. Consequently, tissue spheroids on the membranes expressed high biological activity in terms of oxygen uptake, making them more suitable as building blocks in the fabrication of tissues and organs. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

  4. Correlation between grade of pearlite spheroidization and laser induced spectra

    Science.gov (United States)

    Yao, Shunchun; Dong, Meirong; Lu, Jidong; Li, Jun; Dong, Xuan

    2013-12-01

    Laser induced breakdown spectroscopy (LIBS) which is used traditionally as a spectrochemical analytical technique was employed to analyze the grade of pearlite spheroidization. Three 12Cr1MoV steel specimens with different grades of pearlite spheroidization were ablated to produce plasma by pulse laser at 266 nm. In order to determine the optimal temporal condition and plasma parameters for correlating the grade of pearlite spheroidization and laser induced spectra, a set of spectra at different delays were analyzed by the principal component analysis method. Then, the relationship between plasma temperature, intensity ratios of ionic to atomic lines and grade of pearlite spheroidization was studied. The analysis results show that the laser induced spectra of different grades of pearlite spheroidization can be readily identifiable by principal component analysis in the range of 271.941-289.672 nm with 1000 ns delay time. It is also found that a good agreement exists between the Fe ionic to atomic line ratios and the tensile strength, whereas there is no obvious difference in the plasma temperature. Therefore, LIBS may be applied not only as a spectrochemical analytical technique but also as a new way to estimate the grade of pearlite spheroidization.

  5. Correlation between grade of pearlite spheroidization and laser induced spectra

    International Nuclear Information System (INIS)

    Yao, Shunchun; Dong, Meirong; Lu, Jidong; Li, Jun; Dong, Xuan

    2013-01-01

    Laser induced breakdown spectroscopy (LIBS) which is used traditionally as a spectrochemical analytical technique was employed to analyze the grade of pearlite spheroidization. Three 12Cr1MoV steel specimens with different grades of pearlite spheroidization were ablated to produce plasma by pulse laser at 266 nm. In order to determine the optimal temporal condition and plasma parameters for correlating the grade of pearlite spheroidization and laser induced spectra, a set of spectra at different delays were analyzed by the principal component analysis method. Then, the relationship between plasma temperature, intensity ratios of ionic to atomic lines and grade of pearlite spheroidization was studied. The analysis results show that the laser induced spectra of different grades of pearlite spheroidization can be readily identifiable by principal component analysis in the range of 271.941–289.672 nm with 1000 ns delay time. It is also found that a good agreement exists between the Fe ionic to atomic line ratios and the tensile strength, whereas there is no obvious difference in the plasma temperature. Therefore, LIBS may be applied not only as a spectrochemical analytical technique but also as a new way to estimate the grade of pearlite spheroidization. (paper)

  6. Implications of the dwarfs spheroidal galaxy mass-metallicity relation

    International Nuclear Information System (INIS)

    Smith, G.H.

    1985-01-01

    The properties of the mass-metallicity relation among dwarf spheroidal galaxies are discussed in terms of a model which assumes that the internal chemical evolution of the dwarf spheroidals was promoted by supernova activity. The model can be used to explain the observed dwarf spheroidal mass-metallicity relation assuming the present mass of these systems M sub s is proportional to their initial masses M as M sub s varies according to a power-law index of exp 7/4. It is inferred from the power-law dependence of M on the proto-cloud radius that the most massive dwarf spheroids were formed from the densest clouds. The observed slope of the mass-metallicity relation for dwarf spheroidal galaxies is found to be significantly different from theoretical estimates of this slope for elliptical galaxies. It is suggested that the difference may imply that spheroidal dwarfs and elliptical galaxies had different formation histories, confirming Kormendy's (1985) observations of differences in the brightness and luminosity trends. 54 references

  7. Magnetically levitated mesenchymal stem cell spheroids cultured with a collagen gel maintain phenotype and quiescence

    Directory of Open Access Journals (Sweden)

    Natasha S Lewis

    2017-04-01

    Full Text Available Multicellular spheroids are an established system for three-dimensional cell culture. Spheroids are typically generated using hanging drop or non-adherent culture; however, an emerging technique is to use magnetic levitation. Herein, mesenchymal stem cell spheroids were generated using magnetic nanoparticles and subsequently cultured within a type I collagen gel, with a view towards developing a bone marrow niche environment. Cells were loaded with magnetic nanoparticles, and suspended beneath an external magnet, inducing self-assembly of multicellular spheroids. Cells in spheroids were viable and compared to corresponding monolayer controls, maintained stem cell phenotype and were quiescent. Interestingly, core spheroid necrosis was not observed, even with increasing spheroid size, in contrast to other commonly used spheroid systems. This mesenchymal stem cell spheroid culture presents a potential platform for modelling in vitro bone marrow stem cell niches, elucidating interactions between cells, as well as a useful model for drug delivery studies.

  8. Development of lacrimal gland spheroids for lacrimal gland tissue regeneration.

    Science.gov (United States)

    Massie, Isobel; Spaniol, Kristina; Barbian, Andreas; Geerling, Gerd; Metzger, Marco; Schrader, Stefan

    2018-04-01

    Severe dry eye syndrome resulting from lacrimal gland (LG) dysfunction can cause blindness, yet treatments remain palliative. In vitro reconstruction of LG tissue could provide a curative treatment. We aimed to combine epithelial cells with endothelial cells and mesenchymal stem cells (MSCs) to form a 3D functional unit. Epithelial cells and MSCs were isolated from porcine LG; endothelial cells were isolated from human foreskin. MSCs were characterised (flow cytometry and differentiation potential assays). All 3 cell types were combined on Matrigel and spheroid formation observed. Spheroids were characterised [immunohistochemistry (IHC) and transmission electron microscopy] and function assessed (β-hexosaminidase assay). Spheroids were transferred to decellularised jejunum (SIS-Muc) in dynamic cultures for 1 week before further characterisation. MSCs did not express CD31 but expressed CD44 and CD105 and differentiated towards osteogenic and adipogenic lineages. Spheroids formed on Matrigel within 18 hr, contracting to ~10% of the well area (p function was increased in spheroids cf. monolayer controls (p function (p < .05), viability (p < .05), and proliferation decreased, whilst apoptosis increased. On SIS-Muc under dynamic culture, however, spheroids continued to proliferate to repopulate SIS-Muc. IHC revealed LG epithelial cells coexpressing pan-cytokeratin and lysozyme, as well as endothelial cells and MSCs and cells remained capable of responding to carbachol (p < .05). These spheroids could form the basis of a regenerative medicine treatment approach for dry eye syndrome. In vivo studies are required to evaluate this further. Copyright © 2017 John Wiley & Sons, Ltd.

  9. Human Cardiac Progenitor Spheroids Exhibit Enhanced Engraftment Potential.

    Directory of Open Access Journals (Sweden)

    Francesca Oltolina

    Full Text Available A major obstacle to an effective myocardium stem cell therapy has always been the delivery and survival of implanted stem cells in the heart. Better engraftment can be achieved if cells are administered as cell aggregates, which maintain their extra-cellular matrix (ECM. We have generated spheroid aggregates in less than 24 h by seeding human cardiac progenitor cells (hCPCs onto methylcellulose hydrogel-coated microwells. Cells within spheroids maintained the expression of stemness/mesenchymal and ECM markers, growth factors and their cognate receptors, cardiac commitment factors, and metalloproteases, as detected by immunofluorescence, q-RT-PCR and immunoarray, and expressed a higher, but regulated, telomerase activity. Compared to cells in monolayers, 3D spheroids secreted also bFGF and showed MMP2 activity. When spheroids were seeded on culture plates, the cells quickly migrated, displaying an increased wound healing ability with or without pharmacological modulation, and reached confluence at a higher rate than cells from conventional monolayers. When spheroids were injected in the heart wall of healthy mice, some cells migrated from the spheroids, engrafted, and remained detectable for at least 1 week after transplantation, while, when the same amount of cells was injected as suspension, no cells were detectable three days after injection. Cells from spheroids displayed the same engraftment capability when they were injected in cardiotoxin-injured myocardium. Our study shows that spherical in vivo ready-to-implant scaffold-less aggregates of hCPCs able to engraft also in the hostile environment of an injured myocardium can be produced with an economic, easy and fast protocol.

  10. Radiobiological investigations of multicellular spheroids as an in vitro tumor model. 4

    International Nuclear Information System (INIS)

    Kopp, J.

    1978-01-01

    Multicellular spheroids of various size were irradiated with a single dose of X-rays or fast neutrons, incubated after irradiation in roller tubes for long time, and observed light-microscopically. The observed effects were found independent of the radiation used and dependent on dose (considering the RBE) and size of spheroids. After irradiation the spheroid surface showed a loosening phenomenon and the spheroid structure changed depending on dose in three various types. Up to the 10% survival fraction the spheroids recovered within some days to the structure of non-irradiated spheroids by the growth of the surviving cells. After higher doses single surviving cells inside the dead spheroid material seemed to migrate from the inner hypoxic into the rim zone. They can start proliferation many days after irradiation leading to repopulation of irradiated spheroids. The volume changes of irradiated spheroids were also dose-dependent, but the measurement of spheroid volume seems to be of limited value for predicting the effectiveness of irradiation because the spheroid volume of irradiated spheroids is not proportional to the number of cells per spheroid. (author)

  11. Stark shift and photoionization cross section of on-center and off-center donor impurity in a core/shell ellipsoidal quantum dot

    Science.gov (United States)

    Shi, L.; Yan, Z. W.

    2018-04-01

    Within the framework of the effective-mass approximation and by using a variational method, the Stark shift of on-center and off-center donor impurity binding energies and photoionization cross section under a z-direction electric field in a prolate (oblate) core/shell ellipsoidal quantum dot has been studied. We have calculated the Stark shift as a function of the core and shell sizes and shapes, electric field, and impurity position. We also discuss the photoionization cross section as a function of photon energy with different core and shell sizes and shapes, electric field strengths, and impurity positions. The results show that the Stark shift depends strongly on the impurity position, it could be positive or negative. The core and shell sizes and shapes also have a pronounce influence on the Stark shift, and the Stark shift changes with them is non-monotonic, especially when the impurity is located at the -z-axis, the situation will become complicated. In addition, the core and shell sizes and shapes, impurity position, and electric field also have an important influence on the photoionization cross section. In particular, the photoionization cross section will vanish when the impurity is located at center of spherical core with spherical or prolate shell case at zero field.

  12. Cell proliferation kinetics and radiation response in 9L tumor spheroids

    Energy Technology Data Exchange (ETDEWEB)

    Sweigert, S.E.

    1984-05-01

    Cell kinetic parameters, including population doubling-time, cell cycle time, and growth fraction, were measured in 9L gliosarcoma spheroids. These parameters were studied as the spheroids grew from 50 ..mu..m to over 900 ..mu..m in diameter. Experiments relating the cell kinetic parameters to the radiation response of 9L spheroids were also carried out. The major findings were that the average cell cycle time (T/sub c/), is considerably longer in large spheroids than in exponentially-growing monolayers, the radiosensitivity of noncycling (but still viable) cells in spheroids is not significantly different from that of cycling spheroid cells, and the radiation-induced division delay is approximately twice as long in spheroid cells as in monolayer cells given equal radiation doses. The cell loss factor for spheroids of various sizes was calculated, by using the measured kinetic parameters in the basic equations for growth of a cell population. 157 references, 6 figures, 3 tables.

  13. Cell shedding from X-irradiated multicellular spheroids of human lung carcinomas

    International Nuclear Information System (INIS)

    Sakata, K.; Okada, S.; Suzuki, N.; Majima, H.

    1991-01-01

    We studied the effect of radiation on cell shedding from the surface of multicellular spheroids. Spheroids were produced from two human lung cell lines, one adenocarcinoma (LCT1) and the other small cell carcinoma (LCT2), by using a liquid overlay culture technique. The number of cells shed from both kinds of spheroids did not change significantly when they were irradiated. The number of clonogenic cells shed from both kinds of irradiated spheroids decreased sharply as the dose of irradiation increases. There were no significant differences in clonogenic cell shedding per spheroid between LCT1 and LCT2 spheroids. 400 μm spheroids were more radioresistant to inhibition of clonogenic cell shedding than 250 μm spheroids. Shed cells were more radiosensitive than speroid cells. In these experiments, we did not obtain any results indicating that radiation enchances metastasis. (orig.) [de

  14. Cell proliferation kinetics and radiation response in 9L tumor spheroids

    International Nuclear Information System (INIS)

    Sweigert, S.E.

    1984-05-01

    Cell kinetic parameters, including population doubling-time, cell cycle time, and growth fraction, were measured in 9L gliosarcoma spheroids. These parameters were studied as the spheroids grew from 50 μm to over 900 μm in diameter. Experiments relating the cell kinetic parameters to the radiation response of 9L spheroids were also carried out. The major findings were that the average cell cycle time (T/sub c/), is considerably longer in large spheroids than in exponentially-growing monolayers, the radiosensitivity of noncycling (but still viable) cells in spheroids is not significantly different from that of cycling spheroid cells, and the radiation-induced division delay is approximately twice as long in spheroid cells as in monolayer cells given equal radiation doses. The cell loss factor for spheroids of various sizes was calculated, by using the measured kinetic parameters in the basic equations for growth of a cell population. 157 references, 6 figures, 3 tables

  15. Process for titanium powders spheroidization by RF induction plasma

    International Nuclear Information System (INIS)

    Gu Zhongtao; Ye Gaoying; Liu Chuandong; Tong Honghui

    2010-01-01

    Spherical titanium (Ti) particles were obtained by the process of heating irregularly shaped Ti powders under the radio frequency induction plasma (RF induction plasma) condition. The effect of feed rate, various dispersion methods and Ti particle size on the spheroidization efficiency was studied. The efficiency of the spheroidization is evaluated through the measurements of the percentage of powder spheroidized based on the electron microscopic observations and the tap density measurement of the processed powder. During the short flight of the particles in the plasma flow, of the order of a few milliseconds, the individual titanium particles of the powder are heated and melt, forming a spherical liquid droplet which upon freezing gives rise to the formation of a perfectly dense spherical solid particle. So RF induction plasma is a promising method for the preparation of spherical titanium powders with high flow ability. (authors)

  16. Spheroidization of glass powders for glass ionomer cements.

    Science.gov (United States)

    Gu, Y W; Yap, A U J; Cheang, P; Kumar, R

    2004-08-01

    Commercial angular glass powders were spheroidized using both the flame spraying and inductively coupled radio frequency plasma spraying techniques. Spherical powders with different particle size distributions were obtained after spheroidization. The effects of spherical glass powders on the mechanical properties of glass ionomer cements (GICs) were investigated. Results showed that the particle size distribution of the glass powders had a significant influence on the mechanical properties of GICs. Powders with a bimodal particle size distribution ensured a high packing density of glass ionomer cements, giving relatively high mechanical properties of GICs. GICs prepared by flame-spheroidized powders showed low strength values due to the loss of fine particles during flame spraying, leading to a low packing density and few metal ions reacting with polyacrylic acid to form cross-linking. GICs prepared by the nano-sized powders showed low strength because of the low bulk density of the nano-sized powders and hence low powder/liquid ratio of GICs.

  17. Monoenergetic electron parameters in a spheroid bubble model

    Science.gov (United States)

    Sattarian, H.; Sh., Rahmatallahpur; Tohidi, T.

    2013-02-01

    A reliable analytical expression for the potential of plasma waves with phase velocities near the speed of light is derived. The presented spheroid cavity model is more consistent than the previous spherical and ellipsoidal models and it explains the mono-energetic electron trajectory more accurately, especially at the relativistic region. The maximum energy of electrons is calculated and it is shown that the maximum energy of the spheroid model is less than that of the spherical model. The electron energy spectrum is also calculated and it is found that the energy distribution ratio of electrons ΔE/E for the spheroid model under the conditions reported here is half that of the spherical model and it is in good agreement with the experimental value in the same conditions. As a result, the quasi-mono-energetic electron output beam interacting with the laser plasma can be more appropriately described with this model.

  18. Merging and Splitting of Plasma Spheroids in a Dusty Plasma

    Science.gov (United States)

    Mikikian, Maxime; Tawidian, Hagop; Lecas, Thomas

    2012-12-01

    Dust particle growth in a plasma is a strongly disturbing phenomenon for the plasma equilibrium. It can induce many different types of low-frequency instabilities that can be experimentally observed, especially using high-speed imaging. A spectacular case has been observed in a krypton plasma where a huge density of dust particles is grown by material sputtering. The instability consists of well-defined regions of enhanced optical emission that emerge from the electrode vicinity and propagate towards the discharge center. These plasma spheroids have complex motions resulting from their mutual interaction that can also lead to the merging of two plasma spheroids into a single one. The reverse situation is also observed with the splitting of a plasma spheroid into two parts. These results are presented for the first time and reveal new behaviors in dusty plasmas.

  19. Monoenergetic electron parameters in a spheroid bubble model

    International Nuclear Information System (INIS)

    Sattarian, H.; Rahmatallahpur, Sh.; Tohidi, T.

    2013-01-01

    A reliable analytical expression for the potential of plasma waves with phase velocities near the speed of light is derived. The presented spheroid cavity model is more consistent than the previous spherical and ellipsoidal models and it explains the mono-energetic electron trajectory more accurately, especially at the relativistic region. The maximum energy of electrons is calculated and it is shown that the maximum energy of the spheroid model is less than that of the spherical model. The electron energy spectrum is also calculated and it is found that the energy distribution ratio of electrons ΔE/E for the spheroid model under the conditions reported here is half that of the spherical model and it is in good agreement with the experimental value in the same conditions. As a result, the quasi-mono-energetic electron output beam interacting with the laser plasma can be more appropriately described with this model. (physics of gases, plasmas, and electric discharges)

  20. CONCENTRIC MACLAURIN SPHEROID MODELS OF ROTATING LIQUID PLANETS

    International Nuclear Information System (INIS)

    Hubbard, W. B.

    2013-01-01

    I present exact expressions for the interior gravitational potential V of a system of N concentric constant-density (Maclaurin) spheroids. I demonstrate an iteration procedure to find a self-consistent solution for the shapes of the interfaces between spheroids, and for the interior gravitational potential. The external free-space potential, expressed as a multipole expansion, emerges as part of the self-consistent solution. The procedure is both simpler and more precise than perturbation methods. One can choose the distribution and mass densities of the concentric spheroids so as to reproduce a prescribed barotrope to a specified accuracy. I demonstrate the method's efficacy by comparing its results with several published test cases.

  1. Off-center point explosion in a spheroid

    International Nuclear Information System (INIS)

    Morita, Kazuhiko; Sakashita, Shiro

    1978-01-01

    An off-center point explosion in a spheroid with exponential or Gaussian density distribution is investigated by applying the generalized Laumbach and Probstein method. For a typical example, we calculate the explosion in a spheroid with the eccentricity e = 0.7. If the separation distance between the center of the spheroid and the explosion point is larger than three times of the density scale height, the shock wave may almost propagate toward the direction of the minor axis of symmetry, within the polar angle of 30 0 . The shock envelope elongates toward the same direction and may form a polar jet and/or a tilted jet. But, in the case of an explosion in the equatorial plane (perpendicular to the minor axis of symmetry), two plasmas with the same form may be ejected into two different directions with the angle smaller than 180 0 . Explosion models of double radio sources and related objects are suggested. (author)

  2. Search for Correlations between Prolate-Shape Collective and Oblate-Shape Non-Collective Nuclear Rotation: High Spin States in 159,160 Yb

    International Nuclear Information System (INIS)

    Byrski, T.; Beck, F.A.; Sharpey-Schafer, J.F.

    1987-01-01

    High-spin states of 159,160 Yb have been studied using the escape-suppressed array TESSA 2. Extensions of yrast and lateral bands have been found up to I ∼40. Experimental data suggest strong correlations between maximum alignment configurations of the valence nucleons and related collective states. Theoretical analysis fully supports the idea of prolate-collective vs. oblate-non-collective correlations. Band termination interpretation is discussed

  3. Method for the determination of oxygen consumption rates and diffusion coefficients in multicellular spheroids

    OpenAIRE

    Mueller-Klieser, W.

    1984-01-01

    A method has been developed for the quantitative evaluation of oxygen tension (PO2) distributions in multicellular spheroids measured with O2-sensitive microelectrodes. The experimental data showed that multicellular tumor spheroids in stirred growth media were characterized by a diffusion-depleted zone surrounding the spheroids. This zone was elicited by an unstirred layer of medium next to the spheroid leading to a continuous decrease in the PO2 values from the bulk medium towards the spher...

  4. Halo carbon stars associated with dwarf spheroidal galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Van Den Bergh, S.; Lafontaine, A.

    1984-11-01

    Star counts have been performed for rings centered on the carbon star at 1 69 degrees, b + 55 degrees at a distance of 60 kpc. The counts were performed in order to determine whether halo carbon stars might be situated in dwarf spheroidal galaxies which are too star-poor to have been recognized as galaxies. The counts were made on a IIIa-J plate baked in forming gas that was exposed for 40 minutes through a 2C filter with the Palomar 1.2-m Schmidt telescope. It is shown that the carbon star is not situated in a dwarf spheroidal galaxy brighter than M(V) 5.7.

  5. Heavy-ion radiobiology of multicellular tumor spheroids

    International Nuclear Information System (INIS)

    Rodriguez, A.; Alpen, E.L.

    1980-01-01

    Experiments reported here were conducted with carbon ions, neon ions, and argon ions using rat brain gliosarcoma (9L) and Chinese hamster lung V79 cells grown as multicellular spheroids. Our studies were designed to evaluate high-LET radiation survival characteristics of cells grown in this relatively organized tissue-like environment. Our primary objectives were to determine the RBE values in plateau and spread Bragg peak regions of the carbon, neon, and argon beams, and evaluate with high and low LET radiation, the role of spheroid architecture in postirradiation survival of cells grown in this format

  6. Effects of irradiation and cisplatin on human glioma spheroids: inhibition of cell proliferation and cell migration

    NARCIS (Netherlands)

    Fehlauer, Fabian; Muench, Martina; Rades, Dirk; Stalpers, Lukas J. A.; Leenstra, Sieger; van der Valk, Paul; Slotman, Ben; Smid, Ernst J.; Sminia, Peter

    2005-01-01

    Investigation of cell migration and proliferation of human glioma cell line spheroids (CLS) and evaluation of morphology, apoptosis, and immunohistochemical expression of MIB-1, p53, and p21 of organotypic muticellular spheroids (OMS) following cisplatin (CDDP) and irradiation (RT). Spheroids of the

  7. Biomaterial Substrate-Mediated Multicellular Spheroid Formation and Their Applications in Tissue Engineering.

    Science.gov (United States)

    Tseng, Ting-Chen; Wong, Chui-Wei; Hsieh, Fu-Yu; Hsu, Shan-Hui

    2017-12-01

    Three-dimentional (3D) multicellular aggregates (spheroids), compared to the traditional 2D monolayer cultured cells, are physiologically more similar to the cells in vivo. So far there are various techniques to generate 3D spheroids. Spheroids obtained from different methods have already been applied to regenerative medicine or cancer research. Among the cell spheroids created by different methods, the substrate-derived spheroids and their forming mechanism are unique. This review focuses on the formation of biomaterial substrate-mediated multicellular spheroids and their applications in tissue engineering and tumor models. First, the authors will describe the special chitosan substrate-derived mesenchymal stem cell (MSC) spheroids and their greater regenerative capacities in various tissues. Second, the authors will describe tumor spheroids derived on chitosan and hyaluronan substrates, which serve as a simple in vitro platform to study 3D tumor models or to perform cancer drug screening. Finally, the authors will mention the self-assembly process for substrate-derived multiple cell spheroids (co-spheroids), which may recapitulate the heterotypic cell-cell interaction for co-cultured cells or crosstalk between different types of cells. These unique multicellular mono-spheroids or co-spheroids represent a category of 3D cell culture with advantages of biomimetic cell-cell interaction, better functionalities, and imaging possibilities. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Sulphur, zinc and carbon in the Sculptor dwarf spheroidal galaxy

    NARCIS (Netherlands)

    Skúladóttir, Ása

    2016-01-01

    The Sculptor dwarf spheroidal galaxy is a Milky Way satellite with predominantly old stellar population, and therefore the ideal target to study early chemical evolution. The chemical abundances of photospheres of stars reveal the composition of their birth environment; studying stars of different

  9. The early days of the Sculptor dwarf spheroidal galaxy

    NARCIS (Netherlands)

    Jablonka, P.; North, P.; Mashonkina, L.; Hill, V.; Revaz, Y.; Shetrone, M.; Starkenburg, E.; Irwin, M.; Tolstoy, E.; Battaglia, G.; Venn, K.; Helmi, A.; Primas, F.; François, P.

    2015-01-01

    We present the high-resolution spectroscopic study of five -3.9 ≤ [Fe/H] ≤ -2.5 stars in the Local Group dwarf spheroidal, Sculptor, thereby doubling the number of stars with comparable observations in this metallicity range. We carry out a detailed analysis of the chemical abundances of α, iron

  10. Spheroidal Integral Equations for Geodetic Inversion of Geopotential Gradients

    Science.gov (United States)

    Novák, Pavel; Šprlák, Michal

    2018-03-01

    The static Earth's gravitational field has traditionally been described in geodesy and geophysics by the gravitational potential (geopotential for short), a scalar function of 3-D position. Although not directly observable, geopotential functionals such as its first- and second-order gradients are routinely measured by ground, airborne and/or satellite sensors. In geodesy, these observables are often used for recovery of the static geopotential at some simple reference surface approximating the actual Earth's surface. A generalized mathematical model is represented by a surface integral equation which originates in solving Dirichlet's boundary-value problem of the potential theory defined for the harmonic geopotential, spheroidal boundary and globally distributed gradient data. The mathematical model can be used for combining various geopotential gradients without necessity of their re-sampling or prior continuation in space. The model extends the apparatus of integral equations which results from solving boundary-value problems of the potential theory to all geopotential gradients observed by current ground, airborne and satellite sensors. Differences between spherical and spheroidal formulations of integral kernel functions of Green's kind are investigated. Estimated differences reach relative values at the level of 3% which demonstrates the significance of spheroidal approximation for flattened bodies such as the Earth. The observation model can be used for combined inversion of currently available geopotential gradients while exploring their spectral and stochastic characteristics. The model would be even more relevant to gravitational field modelling of other bodies in space with more pronounced spheroidal geometry than that of the Earth.

  11. The dwarf spheroidal galaxies around the milky way

    NARCIS (Netherlands)

    Tolstoy, E.; Battaglia, G.; Helmi, A.; Irwin, M. J.; Hill, V.; Vallenari, A; Tantalo, R; Portinari, L; Moretti, A

    2007-01-01

    We review the progress of ESO/WFI Imaging and VLT/FLAMES spectroscopy of large numbers of individual stars in nearby dwarf spheroidal galaxies by the Dwarf Abundances and Radial-velocities Team (DART). These observations have allowed us to show that neither the kinematics nor the abundance nor the

  12. Numerical simulations of the metallicity distribution in dwarf spheroidal galaxies

    NARCIS (Netherlands)

    Ripamonti, E.; Tolstoy, E.; Helmi, A.; Battaglia, G.; Abel, T.

    2006-01-01

    Abstract: Recent observations show that the number of stars with very low metallicities in the dwarf spheroidal satellites of the Milky Way is low, despite the low average metallicities of stars in these systems. We undertake numerical simulations of star formation and metal enrichment of dwarf

  13. The dynamical and chemical evolution of dwarf spheroidal galaxies

    NARCIS (Netherlands)

    Revaz, Y.; Jablonka, P.; Sawala, T.; Hill, V.; Letarte, B.; Irwin, M.; Battaglia, G.; Helmi, A.; Shetrone, M. D.; Tolstoy, E.; Venn, K. A.

    We present a large sample of fully self-consistent hydrodynamical Nbody/Tree-SPH simulations of isolated dwarf spheroidal galaxies (dSphs). It has enabled us to identify the key physical parameters and mechanisms at the origin of the observed variety in the Local Group dSph properties. The initial

  14. Estimation of scattering from a moist rough surface with spheroidal ...

    Indian Academy of Sciences (India)

    Administrator

    less than 5⋅5% of the magnetic wavelength. We empha- size that the surface deviation is responsible for scattering at a given electromagnetic wavelength. 2. Theoretical consideration (basic theory). We consider a horizontally rough surface with slight per- centage of moisture (2–4⋅5%) with spheroidal dust parti- cles.

  15. Cryopreservation of organotypic multicellular spheroids from human gliomas

    NARCIS (Netherlands)

    Kaaijk, P.; van den Berg, F.; van Amstel, P.; Troost, D.

    1996-01-01

    Fresh human glioma tissue can be cultured on agarose to form organotypic multicellular spheroids (OMS). The major advantage of OMS is the preservation of the cellular heterogeneity and the tumour architecture, which is lost in conventional monolayer cultures. The present study was undertaken to

  16. Void nucleation in spheroidized steels during tensile deformation

    International Nuclear Information System (INIS)

    Fisher, J.R. Jr.

    1980-04-01

    An investigation was conducted to determine the effects of various mechanical and material parameters on void formation at cementite particles in axisymmetric tensile specimens of spheroidized plain carbon steels. Desired microstructures for each of three steel types were obtained. Observations of void morphology with respect to various microstructural features were made using optical and scanning electron microscopy

  17. Comparative analysis of tumor spheroid generation techniques for differential in vitro drug toxicity

    Science.gov (United States)

    Raghavan, Shreya; Rowley, Katelyn R.; Mehta, Geeta

    2016-01-01

    Multicellular tumor spheroids are powerful in vitro models to perform preclinical chemosensitivity assays. We compare different methodologies to generate tumor spheroids in terms of resultant spheroid morphology, cellular arrangement and chemosensitivity. We used two cancer cell lines (MCF7 and OVCAR8) to generate spheroids using i) hanging drop array plates; ii) liquid overlay on ultra-low attachment plates; iii) liquid overlay on ultra-low attachment plates with rotating mixing (nutator plates). Analysis of spheroid morphometry indicated that cellular compaction was increased in spheroids generated on nutator and hanging drop array plates. Collagen staining also indicated higher compaction and remodeling in tumor spheroids on nutator and hanging drop arrays compared to conventional liquid overlay. Consequently, spheroids generated on nutator or hanging drop plates had increased chemoresistance to cisplatin treatment (20-60% viability) compared to spheroids on ultra low attachment plates (10-20% viability). Lastly, we used a mathematical model to demonstrate minimal changes in oxygen and cisplatin diffusion within experimentally generated spheroids. Our results demonstrate that in vitro methods of tumor spheroid generation result in varied cellular arrangement and chemosensitivity. PMID:26918944

  18. Media additives to promote spheroid circularity and compactness in hanging drop platform.

    Science.gov (United States)

    Leung, Brendan M; Lesher-Perez, Sasha Cai; Matsuoka, Toshiki; Moraes, Christopher; Takayama, Shuichi

    2015-02-01

    Three-dimensional spheroid cultures have become increasingly popular as drug screening platforms, especially with the advent of different high throughput spheroid forming technologies. However, comparing drug efficacy across different cell types in spheroid culture can be difficult due to variations in spheroid morphologies and transport characteristics. Improving the reproducibility of compact, circular spheroids contributes to standardizing and increasing the fidelity of the desired gradient profiles in these drug screening three-dimensional tissue cultures. In this study we discuss the role that circularity and compaction has on spheroids, and demonstrate the impact methylcellulose (MethoCel) and collagen additives in the culture media can contribute to more compact and circular spheroid morphology. We demonstrate that improved spheroid formation is not a simple function of increased viscosity of the different macromolecule additives, suggesting that other macromolecular characteristics contribute to improved spheroid formation. Of the various macromolecular additives tested for hanging drop culture, MethoCel provided the most desirable spheroid formation. Additionally, the higher viscosity of MethoCel-containing media improved the ease of imaging of cellular spheroids within hanging drop cultures by reducing motion-induced image blur.

  19. Spatio-temporal cell dynamics in tumour spheroid irradiation

    International Nuclear Information System (INIS)

    Kempf, H.; Bleicher, M.; Meyer-Hermann, M.; Kempf, H.; Bleicher, M.; Kempf, H.; Meyer-Hermann, M.

    2010-01-01

    Multicellular tumour spheroids are realistic in vitro systems in radiation research that integrate cell-cell interaction and cell cycle control by factors in the medium. The dynamic reaction inside a tumour spheroid triggered by radiation is not well understood. Of special interest is the amount of cell cycle synchronization which could be triggered by irradiation, since this would allow follow-up irradiations to exploit the increased sensitivity of certain cell cycle phases. In order to investigate these questions we need to support irradiation experiments with mathematical models. In this article a new model is introduced combining the dynamics of tumour growth and irradiation treatments. The tumour spheroid growth is modelled using an agent-based Delaunay/Voronoi hybrid model in which the cells are represented by weighted dynamic vertices. Cell properties like full cell cycle dynamics are included. In order to be able to distinguish between different cell reactions in response to irradiation quality we introduce a probabilistic model for damage dynamics. The overall cell survival from this model is in agreement with predictions from the linear-quadratic model. Our model can describe the growth of avascular tumour spheroids in agreement to experimental results. Using the probabilistic model for irradiation damage dynamics the classic 'four Rs' of radiotherapy can be studied in silico. We found a pronounced reactivation of the tumour spheroid in response to irradiation. A majority of the surviving cells is synchronized in their cell cycle progression after irradiation. The cell synchronization could be actively triggered and should be exploited in an advanced fractionation scheme. Thus it has been demonstrated that our model could be used to understand the dynamics of tumour growth after irradiation and to propose optimized fractionation schemes in cooperation with experimental investigations. (authors)

  20. Fluid absorption related to ion transport in human airway epithelial spheroids

    DEFF Research Database (Denmark)

    Pedersen, P S; Holstein-Rathlou, N H; Larsen, P L

    1999-01-01

    , and amiloride inhibited both values. Fluid transport rates were calculated from repeated measurements of spheroid diameters. The results showed that 1) non-CF and CF spheroids absorbed fluid at identical rates (4.4 microl x cm(-2) x h(-1)), 2) amiloride inhibited fluid absorption to a lower residual level...... in non-CF than in CF spheroids, 3) Cl(-)-channel inhibitors increased fluid absorption in amiloride-treated non-CF spheroids to a level equal to that of amiloride-treated CF spheroids, 4) hydrochlorothiazide reduced the amiloride-insensitive fluid absorption in both non-CF and CF spheroids, and 5......) osmotic water permeabilities were equal in non-CF and CF spheroids ( approximately 27 x 10(-7) cm x s(-1) x atm(-1))....

  1. Plasma spheroidization of iron powders in a non-transferred DC thermal plasma jet

    International Nuclear Information System (INIS)

    Kumar, S.; Selvarajan, V.

    2008-01-01

    In this paper, the results of plasma spheroidization of iron powders using a DC non-transferred plasma spray torch are presented. The morphology of the processed powders was characterized through scanning electron microscopy (SEM) and optical microscopy (OM). The percentages of spheroidized powders were calculated by the shape factors such as the Irregularity Parameter (IP) and Roundness (RN). A maximum of 83% of spheroidization can be achieved. The spheroidization results are compared with the theoretical estimation and they are found to be in good agreement. The phase composition of the spheroidized powder was analyzed by XRD. The effect of plasma jet temperature and plasma gas flow rate on spheroidization is discussed. At low plasma gas flow rates and at high plasma jet temperatures, the percentage of spheroidization is high

  2. Shells, orbit bifurcations, and symmetry restorations in Fermi systems

    Energy Technology Data Exchange (ETDEWEB)

    Magner, A. G., E-mail: magner@kinr.kiev.ua; Koliesnik, M. V. [NASU, Institute for Nuclear Research (Ukraine); Arita, K. [Nagoya Institute of Technology, Department of Physics (Japan)

    2016-11-15

    The periodic-orbit theory based on the improved stationary-phase method within the phase-space path integral approach is presented for the semiclassical description of the nuclear shell structure, concerning themain topics of the fruitful activity ofV.G. Soloviev. We apply this theory to study bifurcations and symmetry breaking phenomena in a radial power-law potential which is close to the realistic Woods–Saxon one up to about the Fermi energy. Using the realistic parametrization of nuclear shapes we explain the origin of the double-humped fission barrier and the asymmetry in the fission isomer shapes by the bifurcations of periodic orbits. The semiclassical origin of the oblate–prolate shape asymmetry and tetrahedral shapes is also suggested within the improved periodic-orbit approach. The enhancement of shell structures at some surface diffuseness and deformation parameters of such shapes are explained by existence of the simple local bifurcations and new non-local bridge-orbit bifurcations in integrable and partially integrable Fermi-systems. We obtained good agreement between the semiclassical and quantum shell-structure components of the level density and energy for several surface diffuseness and deformation parameters of the potentials, including their symmetry breaking and bifurcation values.

  3. Dielectrophoresis of Tetraselmis sp., a unicellular green alga, in travelling electric fields analyzed using the RC model for a spheroid

    Directory of Open Access Journals (Sweden)

    Sakshin Bunthawin

    2011-10-01

    Full Text Available Dielectrophoresis of a unicellular green alga, Tetraselmis sp., in a travelling electric field was analyzed using an RC(resistor-capacitor-model, instead of the Laplace approach reported in our previous work. The model consists of resistorcapacitorpairs in series to represent the conductive and the capacitive properties of the shell and the inner part of the spheroid.The model is mathematically simpler than the Laplace model and the RC approach is experimentally superior because only thelower critical frequency [LCF] and cell translational speed are required to be measured experimentally. The effective compleximpedance of the spheroid was mathematically modeled to obtain the Clausius-Mossotti factor ([CMF] as a function of celldielectric properties. Spectra of dielectrophoretic velocity and the lower critical frequency of the marine green alga, Tetraselmissp. were investigated to determine cell dielectric properties using a manual curve-fitting method. Effects of arsenic at differentconcentrations on the cell were examined to verify the model. Arsenic severely decreases cytoplasmic conductance (cwhereas it increases membrane conductance (m. Effects were easily observable even at the lowest concentration of arsenicused experimentally (1 ppm. The method offers a practical means of manipulating small plant cells and for rapid screeningfor effects on the dielectric properties of cells of various applied experimental treatments.

  4. Transfer, imaging, and analysis plate for facile handling of 384 hanging drop 3D tissue spheroids.

    Science.gov (United States)

    Cavnar, Stephen P; Salomonsson, Emma; Luker, Kathryn E; Luker, Gary D; Takayama, Shuichi

    2014-04-01

    Three-dimensional culture systems bridge the experimental gap between in vivo and in vitro physiology. However, nonstandardized formation and limited downstream adaptability of 3D cultures have hindered mainstream adoption of these systems for biological applications, especially for low- and moderate-throughput assays commonly used in biomedical research. Here we build on our recent development of a 384-well hanging drop plate for spheroid culture to design a complementary spheroid transfer and imaging (TRIM) plate. The low-aspect ratio wells of the TRIM plate facilitated high-fidelity, user-independent, contact-based collection of hanging drop spheroids. Using the TRIM plate, we demonstrated several downstream analyses, including bulk tissue collection for flow cytometry, high-resolution low working-distance immersion imaging, and timely reagent delivery for enzymatic studies. Low working-distance multiphoton imaging revealed a cell type-dependent, macroscopic spheroid structure. Unlike ovarian cancer spheroids, which formed loose, disk-shaped spheroids, human mammary fibroblasts formed tight, spherical, and nutrient-limited spheroids. Beyond the applications we describe here, we expect the hanging drop spheroid plate and complementary TRIM plate to facilitate analyses of spheroids across the spectrum of throughput, particularly for bulk collection of spheroids and high-content imaging.

  5. Relations between pH, oxygen partial pressure and growth in cultured cell spheroids.

    Science.gov (United States)

    Carlsson, J; Acker, H

    1988-11-15

    The pH gradients, oxygen partial-pressure gradients and growth curves were measured for 7 different types of spheroids. Growth curves were measured in liquid overlay culture and thereafter the spheroids were attached to cover glasses and transferred to a chamber for micro-electrode measurements. The spheroids were randomly divided for pH or pO2 measurements which then were made under conditions as identical as possible. The decreases in pO2 and pH, delta pO2 and delta pH were calculated as the difference between the values in the culture medium and the values 200 micron inside the spheroids. Each type of spheroid had a certain relation between delta pO2 and delta pH. The human colon carcinoma HT29, the mouse mammary carcinoma EMT6 and the hamster lung V79-379A spheroids had high values of the quotient delta pO2/delta pH. The human thyroid carcinoma HTh7 spheroids and the 3 types of human glioma spheroids had lower quotients. There was a tendency for fast-growing spheroids to have high quotients. Two extreme types of spheroids, HT29 (high quotient) and U-118 MG (low quotient) were analyzed for lactate production and oxygen consumption. The U-118 MG spheroids produced about 3 times more lactate and consumed about 3 times less oxygen than the HT29 spheroids. The differences in lactate production could not be explained by differences in the pyruvate Km values of lactate dehydrogenase. The results indicate that there are significant metabolic differences between the spheroid systems studied.

  6. Dark matter annihilations search in dwarf spheroidal galaxies with fermi

    International Nuclear Information System (INIS)

    Farnier, C.; Nuss, E.; Cohen-Tanugi, J.

    2011-01-01

    Launched in June 2008, the Fermi Gamma-ray Telescope includes a pair conversion detector designed for the 20 MeV to ∼300GeV gamma-ray sky study, the Large Area Telescope (LAT). Operating in all-sky survey mode, its excellent sensitivity and angular resolution will allow either to discover or constrain a signal coming through the annihilation of dark matter particles. Predicted by cold dark matter scenarios as the largest clumps, dwarf spheroidal galaxies are amongst the most attractive targets for indirect search of dark matter by gamma-ray experiments. We present here an overview of the Fermi LAT Dark Matter and New Physics Working Group efforts in the searches of gamma-ray fluxes coming from WIMP pair annihilations in dwarf spheroidal galaxies.

  7. Magnetohydrodynamic stability of spheromak plasma in spheroidal flux conserver

    International Nuclear Information System (INIS)

    Kaneko, Shobu; Kamitani, Atsushi.

    1985-11-01

    The MHD equilibrium configurations of spheromak plasmas in a spheroidal flux conserver are determined by use of a pressure distribution whose derivative dp/dψ vanishes on the magnetic axis, and by use of an optimized distribution. Here p is the pressure and ψ is the flux function. These equilibria are shown to be stable for symmetric modes. The stability for localized modes is investigated by the Mercier criterion. The values of the maximum beta ratio β max are evaluated for both pressure distributions and are shown to become about two times larger by optimization. If the condition, q axis max are found to be less than 30 %. The oblate spheroidal flux conserver is shown to be better than the toroidal conserver with a rectangular cross section from the standpoint of stability. (author)

  8. A 2-D nucleation-growth model of spheroidal graphite

    International Nuclear Information System (INIS)

    Lacaze, Jacques; Bourdie, Jacques; Castro-Román, Manuel Jesus

    2017-01-01

    Analysis of recent experimental investigations, in particular by transmission electron microscopy, suggests spheroidal graphite grows by 2-D nucleation of new graphite layers at the outer surface of the nodules. These layers spread over the surface along the prismatic direction of graphite which is the energetically preferred growth direction of graphite when the apparent growth direction of the nodules is along the basal direction of graphite. 2-D nucleation-growth models first developed for precipitation of pure substances are then adapted to graphite growth from the liquid in spheroidal graphite cast irons. Lateral extension of the new graphite layers is controlled by carbon diffusion in the liquid. This allows describing quantitatively previous experimental results giving strong support to this approach.

  9. Mass transfer inside oblate spheroidal solids: modelling and simulation

    Directory of Open Access Journals (Sweden)

    J. E. F. Carmo

    2008-03-01

    Full Text Available A numerical solution of the unsteady diffusion equation describing mass transfer inside oblate spheroids, considering a constant diffusion coefficient and the convective boundary condition, is presented. The diffusion equation written in the oblate spheroidal coordinate system was used for a two-dimensional case. The finite-volume method was employed to discretize the basic equation. The linear equation set was solved iteratively using the Gauss-Seidel method. As applications, the effects of the Fourier number, the Biot number and the aspect ratio of the body on the drying rate and moisture content during the process are presented. To validate the methodology, results obtained in this work are compared with analytical results of the moisture content encountered in the literature and good agreement was obtained. The results show that the model is consistent and it may be used to solve cases such as those that include disks and spheres and/or those with variable properties with small modifications.

  10. Spheroidization of inorganic compounds by the LPPS method

    Czech Academy of Sciences Publication Activity Database

    Mastný, L.; Brožek, Vlastimil; Medřický, Jan; Marek, I.

    2017-01-01

    Roč. 13, č. 1 (2017), s. 162 ISSN 1336-7242. [Zjazd chemikov /69./. 11.09.2017-15.09.2017, Vysoké Tatry, Starý Smokovec] R&D Projects: GA ČR GA15-12145S Institutional support: RVO:61389021 Keywords : Water stabilized plasma * Liquid precursor plasma spraying * nanoparticles * spheroidization Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics)

  11. Sulphur, zinc and carbon in the Sculptor dwarf spheroidal galaxy

    OpenAIRE

    Skúladóttir, Ása

    2016-01-01

    The Sculptor dwarf spheroidal galaxy is a Milky Way satellite with predominantly old stellar population, and therefore the ideal target to study early chemical evolution. The chemical abundances of photospheres of stars reveal the composition of their birth environment; studying stars of different ages, therefore, provides insight into the chemical enrichment history of the galaxy in which they dwell. High-resolution spectra of 100 stars were used to further explore the chemical enrichment hi...

  12. Method for Processing Liver Spheroids Using an Automatic Tissue Processor

    Science.gov (United States)

    2016-05-01

    alcohol dehydration and hot liquid wax infiltration. After the water in the tissue is replaced with wax and cooled, it then becomes possible to cut...effective for processing and preparing microscopy slides of liver spheroids. The general process involved formalin fixation, dehydration in a...DPBS);  formalin (37% neutral buffer formaldehyde);  series of alcohol solutions: 70, 80, 95, and 100% ethanol in water; 2  xylene

  13. A study on the spheroidization by palsma spraying

    International Nuclear Information System (INIS)

    Jung, In Ha; Ji, C. G.; Bae, S. O.; Yoon, J. H.; Kwon, H. I.

    2001-01-01

    Spheroidization of a powder in thermal plasma is a plausible method for powder morphology treatment. In this experiment, the spheroidization fraction was decreased with increasing the particle size. The higher fraction of H2 gas and higher probe position resulted in a higher spheroidization fraction. From this study, it follows that the good result could be attained from smaller size particle with higher hydrogen gas fraction and higher probe position. Through the statistical assessment, the results concluded that the effect of hydrogen gas content has more influence than particle size, and the probe position affects lower than the others. The interaction between the probe position and hydrogen gas fraction affects more than the other interactions. This alluded that the result largely depended on the particle size and hydrogen gas fraction, and there was an interaction between probe position and hydrogen gas fraction. Therefore, when altering the H2 gas fraction is considered, altering the probe position should also be considered. The fractions of each effect were roughly 25% by particle size, 9% by probe position and 35% by H2 gas fraction. At the results of X-ray diffraction patterns of the spheroidized particles, the large particle exhibited higher content of tetragonal phase, while smaller particle showed nearly cubic phase. This seemed to be the quenching rate; larger particle might have more time to phase separation upon cooling that smaller one. X-ray analysis results confirmed a relation between the particle size and tetragonal phase content, when the particles were sprayed at the same conditions. When particles were the same size but sprayed at different conditions, different content of tetragonal phase exhibited according to the experienced temperatures of particles. A particle wasting longer time for cooling to room temperature showed much tetragonal content which phase is stable at low temperatures

  14. A study on the spheroidization by palsma spraying

    Energy Technology Data Exchange (ETDEWEB)

    Jung, In Ha; Ji, C. G.; Bae, S. O.; Yoon, J. H.; Kwon, H. I

    2001-01-01

    Spheroidization of a powder in thermal plasma is a plausible method for powder morphology treatment. In this experiment, the spheroidization fraction was decreased with increasing the particle size. The higher fraction of H2 gas and higher probe position resulted in a higher spheroidization fraction. From this study, it follows that the good result could be attained from smaller size particle with higher hydrogen gas fraction and higher probe position. Through the statistical assessment, the results concluded that the effect of hydrogen gas content has more influence than particle size, and the probe position affects lower than the others. The interaction between the probe position and hydrogen gas fraction affects more than the other interactions. This alluded that the result largely depended on the particle size and hydrogen gas fraction, and there was an interaction between probe position and hydrogen gas fraction. Therefore, when altering the H2 gas fraction is considered, altering the probe position should also be considered. The fractions of each effect were roughly 25% by particle size, 9% by probe position and 35% by H2 gas fraction. At the results of X-ray diffraction patterns of the spheroidized particles, the large particle exhibited higher content of tetragonal phase, while smaller particle showed nearly cubic phase. This seemed to be the quenching rate; larger particle might have more time to phase separation upon cooling that smaller one. X-ray analysis results confirmed a relation between the particle size and tetragonal phase content, when the particles were sprayed at the same conditions. When particles were the same size but sprayed at different conditions, different content of tetragonal phase exhibited according to the experienced temperatures of particles. A particle wasting longer time for cooling to room temperature showed much tetragonal content which phase is stable at low temperatures.

  15. Scaffold-free Prevascularized Microtissue Spheroids for Pulp Regeneration.

    Science.gov (United States)

    Dissanayaka, W L; Zhu, L; Hargreaves, K M; Jin, L; Zhang, C

    2014-12-01

    Creating an optimal microenvironment that mimics the extracellular matrix (ECM) of natural pulp and securing an adequate blood supply for the survival of cell transplants are major hurdles that need to be overcome in dental pulp regeneration. However, many currently available scaffolds fail to mimic essential functions of natural ECM. The present study investigated a novel approach involving the use of scaffold-free microtissue spheroids of dental pulp stem cells (DPSCs) prevascularized by human umbilical vein endothelial cells (HUVECs) in pulp regeneration. In vitro-fabricated microtissue spheroids were inserted into the canal space of tooth-root slices and were implanted subcutaneously into immunodeficient mice. Histological examination revealed that, after four-week implantation, tooth-root slices containing microtissue spheroids resulted in well-vascularized and cellular pulp-like tissues, compared with empty tooth-root slices, which were filled with only subcutaneous fat tissue. Immunohistochemical staining indicated that the tissue found in the tooth-root slices was of human origin, as characterized by the expression of human mitochondria, and contained odontoblast-like cells organized along the dentin, as assessed by immunostaining for nestin and dentin sialoprotein (DSP). Vascular structures formed by HUVECs in vitro were successfully anastomosed with the host vasculature upon transplantation in vivo, as shown by immunostaining for human CD31. Collectively, these findings demonstrate that prevascularized, scaffold-free, microtissue spheroids can successfully regenerate vascular dental pulp-like tissue and also highlight the significance of the microtissue microenvironment as an optimal environment for successful pulp-regeneration strategies. © International & American Associations for Dental Research.

  16. Reparative Spheroids in HPV-Associated Chronic Cervicitis

    Directory of Open Access Journals (Sweden)

    Gennadiy T. Sukhikh

    2013-09-01

    Full Text Available Background: Spheroid cell structures (SCS described in cell culture are used to study cell-cell and cell-matrix interactions. However, the role of the SCS in the repair process in vivo remains unexplored. The aim of the study was to examine the cellular composition of the spherical structures and their functional significance in the repair of the squamous epithelium in human papilloma virus-associated chronic cervicitis (HPV-CC. Methods and Results: The cytology and biopsy materials from 223 patients with HPV-CC were subjected to molecular testing for HPV DNA by Real-Time Polymerase Chain Reaction (Real-Time PCR with genotyping and chromogenic in situ hybridization (CISH, as well as immunocytological and immunohistochemical analyses of p16INK4A, Ki67, SMA, Vimentin, CD34, E-cadherin, Oct4, CD44, CKW markers. In the stem cell niche zone, these spheroid structures were discovered having proliferative activity and showing signs of producing stem cells involved in the repair of the cervical mucosa in HPV-CC. Conclusion: The persistence of the HPV in the stem cell niche zone cells in the cervix determines the chronization of inflammation in this area, with the ability to perform pathological repair. The immunophenotype of the spheroid cell structures in the HPV-CC includes cells with signs of stem cells (‘stemness’ and the mesenchymal-epithelial transition.

  17. Formation mechanism of spheroidal carbide in ultra-low carbon ductile cast iron

    Directory of Open Access Journals (Sweden)

    Bin-guo Fu

    2016-09-01

    Full Text Available The formation mechanism of the spheroidal carbide in the ultra-low carbon ductile cast iron fabricated by the metal mold casting technique was systematically investigated. The results demonstrated that the spheroidal carbide belonged to eutectic carbide and crystallized in the isolated eutectic liquid phase area. The formation process of the spheroidal carbide was related to the contact and the intersection between the primary dendrite and the secondary dendrite of austenite. The oxides of magnesium, rare earths and other elements can act as heterogeneous nucleation sites for the spheroidal carbide. It was also found that the amount of the spheroidal carbide would increase with an increase in carbon content. The cooling rate has an important influence on the spheroidal carbide under the same chemical composition condition.

  18. Porous Nb-Ti based alloy produced from plasma spheroidized powder

    OpenAIRE

    Li, Qijun; Zhang, Lin; Wei, Dongbin; Ren, Shubin; Qu, Xuanhui

    2017-01-01

    Spherical Nb-Ti based alloy powder was prepared by the combination of plasma spheroidization and mechanical alloying. Phase constituents, microstructure and surface state of the powder, and pore characteristics of the resulting porous alloy were investigated. The results show that the undissolved W and V in the mechanically alloyed powder is fully alloyed after spheroidization, and single β phase is achieved. Particle size of the spheroidized powder is in the range of 20–110 μm. With the decr...

  19. Response of the MG-63 human osteosarcoma cell line grown as multicellular spheroids to neutron irradiation

    International Nuclear Information System (INIS)

    Kubota, Nobuo; Kakehi, Masae; Matsubara, Shou; Koike, Sachiko; Ando, Koichi.

    1993-01-01

    Multicellular tumor spheroids are composed of the mixed populations of cells with regard to cell proliferation, nutrition, oxygenation and radiosensitivity. Human osteogenic sarcoma is generally considered clinically radioresistant. However, the in vitro cell survival curves for human osteogenic sarcoma cell lines do not differ from those of other tumor cell lines. In this study, the responses of human osteogenic sarcoma cell line to gamma ray and neutrons were investigated by using spheroid system. The spheroids of the osteogenic sarcoma cell line are considered to be a good in vitro model of radioresistant tumors. The purpose of this study is to measure the response of the spheroids to fast neutron irradiation. MG-63 human osteogenic sarcoma cell line was used for this study. The cell line was cultured in alpha-MEM with supplement. Cell survival was estimated after the trypsinization of spheroids 24 hours after irradiation. The method of measuring spheroid cure is explained. The mean number of surviving cells per spheroid can be obtained from the mean clonogenic number and cell survival curve. The cell survival of MG-63 spheroids exposed to gamma ray and neutrons and the dose effect curves for spheroid cure after irradiation are shown. (K.I.)

  20. Cell Spheroids with Enhanced Aggressiveness to Mimic Human Liver Cancer In Vitro and In Vivo.

    Science.gov (United States)

    Jung, Hong-Ryul; Kang, Hyun Mi; Ryu, Jea-Woon; Kim, Dae-Soo; Noh, Kyung Hee; Kim, Eun-Su; Lee, Ho-Joon; Chung, Kyung-Sook; Cho, Hyun-Soo; Kim, Nam-Soon; Im, Dong-Soo; Lim, Jung Hwa; Jung, Cho-Rok

    2017-09-05

    We fabricated a spheroid-forming unit (SFU) for efficient and economic production of cell spheroids. We optimized the protocol for generating large and homogenous liver cancer cell spheroids using Huh7 hepatocellular carcinoma (HCC) cells. The large Huh7 spheroids showed apoptotic and proliferative signals in the centre and at the surface, respectively. In particular, hypoxia-induced factor-1 alpha (HIF-1α) and ERK signal activation were detected in the cell spheroids. To diminish core necrosis and increase the oncogenic character, we co-cultured spheroids with 2% human umbilical vein endothelial cells (HUVECs). HUVECs promoted proliferation and gene expression of HCC-related genes and cancer stem cell markers in the Huh7 spheroidsby activating cytokine signalling, mimicking gene expression in liver cancer. HUVECs induced angiogenesis and vessel maturation in Huh7 spheroids in vivo by activating epithelial-mesenchymal transition and angiogenic pathways. The large Huh7 cell spheroids containing HUVECs survived at higher concentrations of anti-cancer drugs (doxorubicin and sorafenib) than did monolayer cells. Our large cell spheroid provides a useful in vitro HCC model to enable intuitive observation for anti-cancer drug testing.

  1. Measuring the light scattering and orientation of a spheroidal particle using in-line holography.

    Science.gov (United States)

    Seo, Kyung Won; Byeon, Hyeok Jun; Lee, Sang Joon

    2014-07-01

    The light scattering properties of a horizontally and vertically oriented spheroidal particle under laser illumination are experimentally investigated using digital in-line holography. The reconstructed wave field shows the bright singular points as a result of the condensed beam formed by a transparent spheroidal particle acting as a lens. The in-plane (θ) and out-of-plane (ϕ) rotating angles of an arbitrarily oriented spheroidal particle are measured by using these scattering properties. As a feasibility test, the 3D orientation of a transparent spheroidal particle suspended in a microscale pipe flow is successfully reconstructed by adapting the proposed method.

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

    International Nuclear Information System (INIS)

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

    1995-01-01

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

  3. IN VITRO INVESTIGATION OF THE TRANSPLANTATION PROSPECTS OF MULTICELLULAR SPHEROID MICROAGGREGATES OF DONOR RETINAL PIGMENT EPITHELIUM

    Directory of Open Access Journals (Sweden)

    S. A. Borzenok

    2015-01-01

    Full Text Available Aim. To study in experiment the criteria for transplantability of multicellular spheroid microaggregates of retinal pigment epithelium (RPE, prepared by the method of 3D cell culture. Materials and Methods. 11 donor eyes (6 of adrenaline index «A», 5 of index «B» were used as a source of RPE cell cultures (group «A» – 6 cultures, group «B» – 5 cultures, of which over 2000 RPE spheroids were obtained by the method of three-dimensional cell culture. 1760 spheroids of them were selected for transplantability investigation (960 – group «A», 800 – group «B». Among the selected spheroids were equal numbers of spheroids of different morphology («smooth» and «rough» and of the initial cell seeding number (500, 1000, 5000, 25 000, 125 000 cells per hanging drop. We were taking out 12 spheroids of group «A» and 10 spheroids of group «B» of the 3D culture in terms of 7, 14, 21, 28 days of 3D culture to assess their viability. We were transferring the same number of spheroids in the same terms from 3D to 2D culture conditions to assess their adhesive properties. Viability of cells within spheroids was determined using the Trypan blue exclusion. The presence or absence of adhesion was determined by microscopic observation.Results. «Smooth» spheroids of 7 and 14 days of pretransplantation cultivation and derived from hanging drops containing 500 and 1000 cells showed the highest transplantability (cell viability varied from 0.83 ± 0.38 to 0.94 ± 0.24, a 100% adhesion. «Rough» spheroids were untransplantable in all variants, despite their partial preservation of viability (in comparison to “smooth” ones p < 0.05. 21 and 28 days of pretransplantation culturing and high cell seeding numbers signifi cantly lowered transplantability of obtained spheroids (p > 0.05 for low cell numbers, p < 0.05 for the high ones. Differences in adrenaline indexes A and B of donor eyes which were the primary sources of cellular

  4. Optimal formation of genetically modified and functional pancreatic islet spheroids by using hanging-drop strategy.

    Science.gov (United States)

    Kim, H J; Alam, Z; Hwang, J W; Hwang, Y H; Kim, M J; Yoon, S; Byun, Y; Lee, D Y

    2013-03-01

    Rejection and hypoxia are important factors causing islet loss at an early stage after pancreatic islet transplantation. Recently, islets have been dissociated into single cells for reaggregation into so-called islet spheroids. Herein, we used a hanging-drop strategy to form islet spheroids to achieve functional equivalence to intact islets. To obtain single islet cells, we dissociated islets with trypsin-EDTA digestion for 10 minutes. To obtain spheroids, we dropped various numbers of single cells (125, 250, or 500 cells/30 μL drop) onto a Petri dish, that was inverted for incubation in humidified air containing 5% CO(2) at 37 °C for 7 days. The aggregated spheroids in the droplets were harvested for further culture. The size of the aggregated islet spheroids depended on the number of single cells (125-500 cells/30 μL droplet). Their morphology was similar to that of intact islets without any cellular damage. When treated with various concentrations of glucose to evaluate responsiveness, their glucose-mediated stimulation index value was similar to that of intact islets, an observation that was attributed to strong cell-to-cell interactions in islet spheroids. However, islet spheroids aggregated in general culture dishes showed abnormal glucose responsiveness owing to weak cell-to-cell interactions. Cell-to-cell interactions in islet spheroids were confirmed with an anti-connexin-36 monoclonal antibody. Finally, nonviral poly(ethylene imine)-mediated interleukin-10 cytokine gene delivered beforehand into dissociated single cells before formation of islet spheroids increased the gene transfection efficacy and interleukin-10 secretion from islet spheroids >4-fold compared with intact islets. These results demonstrated the potential application of genetically modified, functional islet spheroids with of controlled size and morphology using an hanging-drop technique. Copyright © 2013 Elsevier Inc. All rights reserved.

  5. In vitro characterization of self-assembled anterior cruciate ligament cell spheroids for ligament tissue engineering.

    Science.gov (United States)

    Hoyer, M; Meier, C; Breier, A; Hahner, J; Heinrich, G; Drechsel, N; Meyer, M; Rentsch, C; Garbe, L-A; Ertel, W; Lohan, A; Schulze-Tanzil, G

    2015-03-01

    Tissue engineering of an anterior cruciate ligament (ACL) implant with functional enthesis requires site-directed seeding of different cell types on the same scaffold. Therefore, we studied the suitability of self-assembled three-dimensional spheroids generated by lapine ACL ligament fibroblasts for directed scaffold colonization. The spheroids were characterized in vitro during 14 days in static and 7 days in dynamic culture. Size maintenance of self-assembled spheroids, the vitality, the morphology and the expression pattern of the cells were monitored. Additionally, we analyzed the total sulfated glycosaminoglycan, collagen contents and the expression of the ligament components type I collagen, decorin and tenascin C on protein and for COL1A1, DCN and TNMD on gene level in the spheroids. Subsequently, the cell colonization of polylactide-co-caprolactone [P(LA-CL)] and polydioxanone (PDS) polymer scaffolds was assessed in response to a directed, spheroid-based seeding technique. ACL cells were able to self-assemble spheroids and survive over 14 days. The spheroids decreased in size but not in cellularity depending on the culture time and maintained or even increased their differentiation state. The area of P[LA-CL] scaffolds, colonized after 14 days by the cells of one spheroid, was in average 4.57 ± 2.3 mm(2). Scaffolds consisting of the polymer P[LA-CL] were more suitable for colonization by spheroids than PDS embroideries. We conclude that ACL cell spheroids are suitable as site-directed seeding strategy for scaffolds in ACL tissue engineering approaches and recommend the use of freshly assembled spheroids for scaffold colonization, due to their balanced proliferation and differentiation.

  6. Generating Chondromimetic Mesenchymal Stem Cell Spheroids by Regulating Media Composition and Surface Coating.

    Science.gov (United States)

    Sridharan, BanuPriya; Laflin, Amy D; Detamore, Michael S

    2018-04-01

    Spheroids of mesenchymal stem cells (MSCs) in cartilage tissue engineering have been shown to enhance regenerative potential owing to their 3D structure. In this study, we explored the possibility of priming spheroids under different media to replace the use of inductive surface coatings for chondrogenic differentiation. Rat bone marrow-derived MSCs were organized into cell spheroids by the hanging drop technique and subsequently cultured on hyaluronic acid (HA) coated or non-coated well plates under different cell media conditions. Endpoint analysis included cell viability, DNA and Glycosaminoglycan (GAG) and collagen content, gene expression and immunohistochemistry. For chondrogenic applications, MSC spheroids derived on non-coated surfaces outperformed the spheroids derived from HA-coated surfaces in matrix synthesis and collagen II gene expression. Spheroids on non-coated surfaces gave rise to the highest collagen and GAG when primed with medium containing insulin-like growth factor (IGF) for 1 week during spheroid formation. Spheroids that were grown in chondroinductive raw material-inclusive media such as aggrecan or chondroitin sulfate exhibited the highest Collagen II gene expression in the non-coated surface at 1 week. Media priming by growth factors and raw materials might be a more predictive influencer of chondrogenesis compared to inductive-surfaces. Such tailored bioactivity of the stem cell spheroids in the stage of the spheroid formation may give rise to a platform technology that may eventually produce spheroids capable of chondrogenesis achieved by mere media manipulation, skipping the need for additional culture on a modified surface, that paves the way for cost-effective technologies.

  7. Supermassive Black Holes and Their Host Spheroids. I. Disassembling Galaxies

    Science.gov (United States)

    Savorgnan, G. A. D.; Graham, A. W.

    2016-01-01

    Several recent studies have performed galaxy decompositions to investigate correlations between the black hole mass and various properties of the host spheroid, but they have not converged on the same conclusions. This is because their models for the same galaxy were often significantly different and not consistent with each other in terms of fitted components. Using 3.6 μm Spitzer imagery, which is a superb tracer of the stellar mass (superior to the K band), we have performed state-of-the-art multicomponent decompositions for 66 galaxies with directly measured black hole masses. Our sample is the largest to date and, unlike previous studies, contains a large number (17) of spiral galaxies with low black hole masses. We paid careful attention to the image mosaicking, sky subtraction, and masking of contaminating sources. After a scrupulous inspection of the galaxy photometry (through isophotal analysis and unsharp masking) and—for the first time—2D kinematics, we were able to account for spheroids large-scale, intermediate-scale, and nuclear disks bars rings spiral arms halos extended or unresolved nuclear sources; and partially depleted cores. For each individual galaxy, we compared our best-fit model with previous studies, explained the discrepancies, and identified the optimal decomposition. Moreover, we have independently performed one-dimensional (1D) and two-dimensional (2D) decompositions and concluded that, at least when modeling large, nearby galaxies, 1D techniques have more advantages than 2D techniques. Finally, we developed a prescription to estimate the uncertainties on the 1D best-fit parameters for the 66 spheroids that takes into account systematic errors, unlike popular 2D codes that only consider statistical errors.

  8. SUPERMASSIVE BLACK HOLES AND THEIR HOST SPHEROIDS. I. DISASSEMBLING GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Savorgnan, G. A. D.; Graham, A. W., E-mail: gsavorgn@astro.swin.edu.au [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn, Victoria 3122 (Australia)

    2016-01-15

    Several recent studies have performed galaxy decompositions to investigate correlations between the black hole mass and various properties of the host spheroid, but they have not converged on the same conclusions. This is because their models for the same galaxy were often significantly different and not consistent with each other in terms of fitted components. Using 3.6 μm Spitzer imagery, which is a superb tracer of the stellar mass (superior to the K band), we have performed state-of-the-art multicomponent decompositions for 66 galaxies with directly measured black hole masses. Our sample is the largest to date and, unlike previous studies, contains a large number (17) of spiral galaxies with low black hole masses. We paid careful attention to the image mosaicking, sky subtraction, and masking of contaminating sources. After a scrupulous inspection of the galaxy photometry (through isophotal analysis and unsharp masking) and—for the first time—2D kinematics, we were able to account for spheroids; large-scale, intermediate-scale, and nuclear disks; bars; rings; spiral arms; halos; extended or unresolved nuclear sources; and partially depleted cores. For each individual galaxy, we compared our best-fit model with previous studies, explained the discrepancies, and identified the optimal decomposition. Moreover, we have independently performed one-dimensional (1D) and two-dimensional (2D) decompositions and concluded that, at least when modeling large, nearby galaxies, 1D techniques have more advantages than 2D techniques. Finally, we developed a prescription to estimate the uncertainties on the 1D best-fit parameters for the 66 spheroids that takes into account systematic errors, unlike popular 2D codes that only consider statistical errors.

  9. SUPERMASSIVE BLACK HOLES AND THEIR HOST SPHEROIDS. I. DISASSEMBLING GALAXIES

    International Nuclear Information System (INIS)

    Savorgnan, G. A. D.; Graham, A. W.

    2016-01-01

    Several recent studies have performed galaxy decompositions to investigate correlations between the black hole mass and various properties of the host spheroid, but they have not converged on the same conclusions. This is because their models for the same galaxy were often significantly different and not consistent with each other in terms of fitted components. Using 3.6 μm Spitzer imagery, which is a superb tracer of the stellar mass (superior to the K band), we have performed state-of-the-art multicomponent decompositions for 66 galaxies with directly measured black hole masses. Our sample is the largest to date and, unlike previous studies, contains a large number (17) of spiral galaxies with low black hole masses. We paid careful attention to the image mosaicking, sky subtraction, and masking of contaminating sources. After a scrupulous inspection of the galaxy photometry (through isophotal analysis and unsharp masking) and—for the first time—2D kinematics, we were able to account for spheroids; large-scale, intermediate-scale, and nuclear disks; bars; rings; spiral arms; halos; extended or unresolved nuclear sources; and partially depleted cores. For each individual galaxy, we compared our best-fit model with previous studies, explained the discrepancies, and identified the optimal decomposition. Moreover, we have independently performed one-dimensional (1D) and two-dimensional (2D) decompositions and concluded that, at least when modeling large, nearby galaxies, 1D techniques have more advantages than 2D techniques. Finally, we developed a prescription to estimate the uncertainties on the 1D best-fit parameters for the 66 spheroids that takes into account systematic errors, unlike popular 2D codes that only consider statistical errors

  10. WFPC2 Observations of the URSA Minor Dwarf Spheroidal Galaxy

    Science.gov (United States)

    Mighell, Kenneth J.; Burke, Christopher J.

    1999-01-01

    We present our analysis of archival Hubble Space Telescope Wide Field Planetary Camera 2 (WFPC2) observations in F555W (approximately V) and F814W (approximately I) of the central region of the Ursa Minor dwarf spheroidal galaxy. The V versus V - I color-magnitude diagram features a sparsely populated blue horizontal branch, a steep thin red giant branch, and a narrow subgiant branch. The main sequence reaches approximately 2 magnitudes below the main-sequence turnoff (V(sup UMi, sub TO) approximately equals 23.27 +/- 0.11 mag) of the median stellar population. We compare the fiducial sequence of the Galactic globular cluster M92 (NGC 6341). The excellent match between Ursa Minor and M92 confirms that the median stellar population of the UMi dSph galaxy is metal poor ([Fe/H](sub UMi) approximately equals [Fe/H](sub M92) approximately equals -2.2 dex) and ancient (age(sub UMi)approximately equalsage(sub M92) approximately equals 14 Gyr). The B - V reddening and the absorption in V are estimated to be E(B - V) = 0.03 +/- 0.01 mag and A(sup UMi, sub V) = 0.09 +/- 0.03 mag. A new estimate of the distance modulus of Ursa Minor, (m - M)(sup UMi, sub 0) = 19.18 +/- 0.12 mag, has been derived based on fiducial-sequence fitting M92 [DELTA.V(sub UMi - M92) = 4.60 +/- 0.03 mag and DELTA(V - I)(sub UMi - M92) = 0.010 +/- 0.005 mag] and the adoption of the apparent V distance modulus for M92 of (m - M)(sup M92, sub V) = 14.67 +/- 0.08 mag (Pont et al. 1998, A&A, 329, 87). The Ursa Minor dwarf spheroidal galaxy is then at a distance of 69 +/- 4 kpc from the Sun. These HST observations indicate that Ursa Minor has had a very simple star formation history consisting mainly of a single major burst of star formation about 14 Gyr ago which lasted approximately stars in the central region Ursa Minor dwarf spheroidal galaxy are ancient. If the ancient Galactic globular clusters, like M92, formed concurrently with the early formation of the Milky Way galaxy itself, then the Ursa Minor

  11. PREDICTION OF THE EXTREMAL SHAPE FACTOR OF SPHEROIDAL PARTICLES

    Directory of Open Access Journals (Sweden)

    Daniel Hlubinka

    2011-05-01

    Full Text Available In the stereological unfolding problem for spheroidal particles the extremal shape factor is predicted. The theory of extreme values has been used to show that extremes of the planar shape factor of particle sections tend to the same limit distribution as extremes of the original shape factor for both the conditional and marginal distribution. Attention is then paid to the extreme shape factor conditioned by the particle size. Normalizing constants are evaluated for a parametric model and the numerical procedure is tested on real data from metallography.

  12. Modes of spheroidal ion plasmas at the Brillouin limit

    International Nuclear Information System (INIS)

    Tinkle, M. D.; Greaves, R. G.; Surko, C. M.

    1995-01-01

    Brillouin-density pure ion plasmas have been generated in a quadrupole Penning tray by electron-beam ionization of a low-pressure gas. Large, spheroidal, steady-state plasmas are produced that extend to one of the trap electrodes. With the density fixed at the Brillouin limit by the high ion production rate, the electrode potentials determine the plasma shape. The frequencies of azimuthally propagating cyclotron and diocotron modes are found to vary significantly with the plasma aspect ratio. For oblate plasmas, we are able to test theoretical predictions of a simple fluid model, and the frequencies are in good agreement

  13. Scattering of Gaussian beam by a spherical particle with a spheroidal inclusion

    International Nuclear Information System (INIS)

    Zhang Huayong; Liao Tongqing

    2011-01-01

    A generalized Lorenz-Mie theory framework (GLMT) is applied to the study of Gaussian beam scattering by a spherical particle with an embedded spheroid at the center. By virtue of a transformation between the spherical and spheroidal vector wave functions, a theoretical procedure is developed to deal with the boundary conditions. Numerical results of the normalized differential scattering cross section are presented.

  14. Spheroidal corrections to the spherical and parabolic bases of the hydrogen atom

    International Nuclear Information System (INIS)

    Mardyan, L.G.; Pogosyan, G.S.; Sisakyan, A.N.

    1986-01-01

    This paper introduces the bases of the hydrogen atom and obtains recursion relations that determine the expansion of the spheroidal basis with respect to its parabolic basis. The leading spheroidal corrections to the spherical and parabolic bases are calculated by perturbation theory

  15. Stability of self-gravitating homogeneous spheroid with azimuthal magnetic field. I

    International Nuclear Information System (INIS)

    Antonov, V.A.; Zheleznyak, O.A.

    1988-01-01

    The influence of a frozen magnetic field on the stability of a self-gravitating homogeneous spheroid with respect to a deformation that transforms it into a triaxial ellipsoid is investigated. It is shown that an azimuthal magnetic field is a stabilizing factor, allowing the spheroid to be stable at e > e/sub cr/ = 0.95285

  16. Multiscale image analysis reveals structural heterogeneity of the cell microenvironment in homotypic spheroids.

    Science.gov (United States)

    Schmitz, Alexander; Fischer, Sabine C; Mattheyer, Christian; Pampaloni, Francesco; Stelzer, Ernst H K

    2017-03-03

    Three-dimensional multicellular aggregates such as spheroids provide reliable in vitro substitutes for tissues. Quantitative characterization of spheroids at the cellular level is fundamental. We present the first pipeline that provides three-dimensional, high-quality images of intact spheroids at cellular resolution and a comprehensive image analysis that completes traditional image segmentation by algorithms from other fields. The pipeline combines light sheet-based fluorescence microscopy of optically cleared spheroids with automated nuclei segmentation (F score: 0.88) and concepts from graph analysis and computational topology. Incorporating cell graphs and alpha shapes provided more than 30 features of individual nuclei, the cellular neighborhood and the spheroid morphology. The application of our pipeline to a set of breast carcinoma spheroids revealed two concentric layers of different cell density for more than 30,000 cells. The thickness of the outer cell layer depends on a spheroid's size and varies between 50% and 75% of its radius. In differently-sized spheroids, we detected patches of different cell densities ranging from 5 × 10 5 to 1 × 10 6  cells/mm 3 . Since cell density affects cell behavior in tissues, structural heterogeneities need to be incorporated into existing models. Our image analysis pipeline provides a multiscale approach to obtain the relevant data for a system-level understanding of tissue architecture.

  17. Oxygenation and response to irradiation of organotypic multicellular spheroids of human glioma.

    Science.gov (United States)

    Sminia, Peter; Acker, Helmut; Eikesdal, Hans Petter; Kaaijk, Patricia; Enger, Per øvind; Slotman, Ben; Bjerkvig, Rolf

    2003-01-01

    Investigation of the oxygenation status of organotypic multicellular spheroids (OMS) and their response to irradiation. Tumour specimens of glioblastoma multiforme patients (n = 16) were initiated as OMS. Following 20 Gy gamma-irradiation, the cell migratory capacity was evaluated. Spheroid oxygenation was determined by micro-electrode pO2 measurements and pimonidazole immunostaining. Spheroids prepared from established human glioma cell lines were used as a reference. Irradiation inhibited spheroid outgrowth by 12 to 88% relative to the non-irradiated controls. A large interpatient variation was noticed. Oxygen measurements revealed a gradual decrease in pO2 level from the periphery to the core of the spheroids, but the pO2 values remained within an oxygenated range. However, in the cell line spheroids an intermediate layer of hypoxia surrounding the central core was observed. Cell line spheroids with a hypoxic cell fraction and well-oxygenated OMS both show high resistance to irradiation, indicating that hypoxia may not be the biological factor determining the radioresistance of glioma spheroids in vitro.

  18. Synergistic interaction between cisplatin and gemcitabine in neuroblastoma cell lines and multicellular tumor spheroids

    NARCIS (Netherlands)

    Besançon, Odette G.; Tytgat, Godelieve A. M.; Meinsma, Rutger; Leen, René; Hoebink, Jerry; Kalayda, Ganna V.; Jaehde, Ulrich; Caron, Huib N.; van Kuilenburg, André B. P.

    2012-01-01

    The efficacy and mechanism of action of cisplatin and gemcitabine were investigated in a panel of neuroblastoma cell lines and multicellular tumor spheroids. In neuroblastoma spheroids, the combination of cisplatin and gemcitabine induced a complete cytostasis at clinical relevant concentrations. A

  19. Solid freeform-fabricated scaffolds designed to carry multicellular mesenchymal stem cell spheroids for cartilage regeneration

    Directory of Open Access Journals (Sweden)

    G-S Huang

    2013-10-01

    Full Text Available Three-dimensional (3D cellular spheroids have recently emerged as a new trend to replace suspended single cells in modern cell-based therapies because of their greater regeneration capacities in vitro. They may lose the 3D structure during a change of microenvironment, which poses challenges to their translation in vivo. Besides, the conventional microporous scaffolds may have difficulty in accommodating these relatively large spheroids. Here we revealed a novel design of microenvironment for delivering and sustaining the 3D spheroids. Biodegradable scaffolds with macroporosity to accommodate mesenchymal stem cell (MSC spheroids were made by solid freeform fabrication (SFF from the solution of poly(D,L-lactide-co-glycolide. Their internal surface was modified with chitosan following air plasma treatment in order to preserve the morphology of the spheroids. It was demonstrated that human MSC spheroids loaded in SFF scaffolds produced a significantly larger amount of cartilage-associated extracellular matrix in vitro and in NOD/SCID mice compared to single cells in the same scaffolds. Implantation of MSC spheroid-loaded scaffolds into the chondral defects of rabbit knees showed superior cartilage regeneration. This study establishes new perspectives in designing the spheroid-sustaining microenvironment within a tissue engineering scaffold for in vivo applications.

  20. An mDia2/ROCK signaling axis regulates invasive egress from epithelial ovarian cancer spheroids.

    Science.gov (United States)

    Pettee, Krista M; Dvorak, Kaitlyn M; Nestor-Kalinoski, Andrea L; Eisenmann, Kathryn M

    2014-01-01

    Multi-cellular spheroids are enriched in ascites of epithelial ovarian cancer (OvCa) patients. They represent an invasive and chemoresistant cellular population fundamental to metastatic dissemination. The molecular mechanisms triggering single cell invasive egress from spheroids remain enigmatic. mDia formins are Rho GTPase effectors that are key regulators of F-actin cytoskeletal dynamics. We hypothesized that mDia2-driven F-actin dynamics promote single cell invasive transitions in clinically relevant three-dimensional (3D) OvCa spheroids. The current study is a dissection of the contribution of the F-actin assembly factor mDia2 formin in invasive transitions and using a clinically relevant ovarian cancer spheroid model. We show that RhoA-directed mDia2 activity is required for tight spheroid organization, and enrichment of mDia2 in the invasive cellular protrusions of collagen-embedded OVCA429 spheroids. Depleting mDia2 in ES-2 spheroids enhanced invasive dissemination of single amoeboid-shaped cells. This contrasts with spheroids treated with control siRNA, where a mesenchymal invasion program predominated. Inhibition of another RhoA effector, ROCK, had no impact on ES-2 spheroid formation but dramatically inhibited spheroid invasion through induction of a highly elongated morphology. Concurrent inhibition of ROCK and mDia2 blocked single cell invasion from ES-2 spheroids more effectively than inhibition of either protein alone, indicating that invasive egress of amoeboid cells from mDia2-depleted spheroids is ROCK-dependent. Our findings indicate that multiple GTPase effectors must be suppressed in order to fully block invasive egress from ovarian cancer spheroids. Furthermore, tightly regulated interplay between ROCK and mDia2 signaling pathways dictates the invasive capacities and the type of invasion program utilized by motile spheroid-derived ovarian cancer cells. As loss of the gene encoding mDia2, DRF3, has been linked to cancer progression and

  1. An mDia2/ROCK signaling axis regulates invasive egress from epithelial ovarian cancer spheroids.

    Directory of Open Access Journals (Sweden)

    Krista M Pettee

    Full Text Available Multi-cellular spheroids are enriched in ascites of epithelial ovarian cancer (OvCa patients. They represent an invasive and chemoresistant cellular population fundamental to metastatic dissemination. The molecular mechanisms triggering single cell invasive egress from spheroids remain enigmatic. mDia formins are Rho GTPase effectors that are key regulators of F-actin cytoskeletal dynamics. We hypothesized that mDia2-driven F-actin dynamics promote single cell invasive transitions in clinically relevant three-dimensional (3D OvCa spheroids. The current study is a dissection of the contribution of the F-actin assembly factor mDia2 formin in invasive transitions and using a clinically relevant ovarian cancer spheroid model. We show that RhoA-directed mDia2 activity is required for tight spheroid organization, and enrichment of mDia2 in the invasive cellular protrusions of collagen-embedded OVCA429 spheroids. Depleting mDia2 in ES-2 spheroids enhanced invasive dissemination of single amoeboid-shaped cells. This contrasts with spheroids treated with control siRNA, where a mesenchymal invasion program predominated. Inhibition of another RhoA effector, ROCK, had no impact on ES-2 spheroid formation but dramatically inhibited spheroid invasion through induction of a highly elongated morphology. Concurrent inhibition of ROCK and mDia2 blocked single cell invasion from ES-2 spheroids more effectively than inhibition of either protein alone, indicating that invasive egress of amoeboid cells from mDia2-depleted spheroids is ROCK-dependent. Our findings indicate that multiple GTPase effectors must be suppressed in order to fully block invasive egress from ovarian cancer spheroids. Furthermore, tightly regulated interplay between ROCK and mDia2 signaling pathways dictates the invasive capacities and the type of invasion program utilized by motile spheroid-derived ovarian cancer cells. As loss of the gene encoding mDia2, DRF3, has been linked to cancer

  2. Multiplexing spheroid volume, resazurin and acid phosphatase viability assays for high-throughput screening of tumour spheroids and stem cell neurospheres.

    Directory of Open Access Journals (Sweden)

    Delyan P Ivanov

    Full Text Available Three-dimensional cell culture has many advantages over monolayer cultures, and spheroids have been hailed as the best current representation of small avascular tumours in vitro. However their adoption in regular screening programs has been hindered by uneven culture growth, poor reproducibility and lack of high-throughput analysis methods for 3D. The objective of this study was to develop a method for a quick and reliable anticancer drug screen in 3D for tumour and human foetal brain tissue in order to investigate drug effectiveness and selective cytotoxic effects. Commercially available ultra-low attachment 96-well round-bottom plates were employed to culture spheroids in a rapid, reproducible manner amenable to automation. A set of three mechanistically different methods for spheroid health assessment (Spheroid volume, metabolic activity and acid phosphatase enzyme activity were validated against cell numbers in healthy and drug-treated spheroids. An automated open-source ImageJ macro was developed to enable high-throughput volume measurements. Although spheroid volume determination was superior to the other assays, multiplexing it with resazurin reduction and phosphatase activity produced a richer picture of spheroid condition. The ability to distinguish between effects on malignant and the proliferating component of normal brain was tested using etoposide on UW228-3 medulloblastoma cell line and human neural stem cells. At levels below 10 µM etoposide exhibited higher toxicity towards proliferating stem cells, whereas at concentrations above 10 µM the tumour spheroids were affected to a greater extent. The high-throughput assay procedures use ready-made plates, open-source software and are compatible with standard plate readers, therefore offering high predictive power with substantial savings in time and money.

  3. A theoretical study of the spheroidal droplet evaporation in forced convection

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jie, E-mail: leejay1986@163.com; Zhang, Jian

    2014-11-07

    In many applications, the shape of a droplet may be assumed to be an oblate spheroid. A theoretical study is conducted on the evaporation of an oblate spheroidal droplet under forced convection conditions. Closed-form analytical expressions of the mass evaporation rate for an oblate spheroid are derived, in the regime of controlled mass-transfer and heat-transfer, respectively. The variation of droplet size during the evaporation process is presented in the regime of shrinking dynamic model. Comparing with the droplets having the same surface area, an increase in the aspect ratio enhances the mass evaporation rate and prolongs the burnout time. - Highlights: • Fully algebraic solutions for the spheroidal droplet evaporation rate is obtained. • We examine the effect of aspect ratio on the droplet evaporation. • We propose a calculation method of Nusselt number for spheroidal droplet.

  4. Creation of Cardiac Tissue Exhibiting Mechanical Integration of Spheroids Using 3D Bioprinting.

    Science.gov (United States)

    Ong, Chin Siang; Fukunishi, Takuma; Nashed, Andrew; Blazeski, Adriana; Zhang, Huaitao; Hardy, Samantha; DiSilvestre, Deborah; Vricella, Luca; Conte, John; Tung, Leslie; Tomaselli, Gordon; Hibino, Narutoshi

    2017-07-02

    This protocol describes 3D bioprinting of cardiac tissue without the use of biomaterials, using only cells. Cardiomyocytes, endothelial cells and fibroblasts are first isolated, counted and mixed at desired cell ratios. They are co-cultured in individual wells in ultra-low attachment 96-well plates. Within 3 days, beating spheroids form. These spheroids are then picked up by a nozzle using vacuum suction and assembled on a needle array using a 3D bioprinter. The spheroids are then allowed to fuse on the needle array. Three days after 3D bioprinting, the spheroids are removed as an intact patch, which is already spontaneously beating. 3D bioprinted cardiac patches exhibit mechanical integration of component spheroids and are highly promising in cardiac tissue regeneration and as 3D models of heart disease.

  5. A theoretical study of the spheroidal droplet evaporation in forced convection

    International Nuclear Information System (INIS)

    Li, Jie; Zhang, Jian

    2014-01-01

    In many applications, the shape of a droplet may be assumed to be an oblate spheroid. A theoretical study is conducted on the evaporation of an oblate spheroidal droplet under forced convection conditions. Closed-form analytical expressions of the mass evaporation rate for an oblate spheroid are derived, in the regime of controlled mass-transfer and heat-transfer, respectively. The variation of droplet size during the evaporation process is presented in the regime of shrinking dynamic model. Comparing with the droplets having the same surface area, an increase in the aspect ratio enhances the mass evaporation rate and prolongs the burnout time. - Highlights: • Fully algebraic solutions for the spheroidal droplet evaporation rate is obtained. • We examine the effect of aspect ratio on the droplet evaporation. • We propose a calculation method of Nusselt number for spheroidal droplet

  6. Universal timescales in the rheology of spheroid cell aggregates

    Science.gov (United States)

    Yu, Miao; Mahtabfar, Aria; Beleen, Paul; Foty, Ramsey; Zahn, Jeffrey; Shreiber, David; Liu, Liping; Lin, Hao

    2017-11-01

    The rheological properties of tissue play important roles in key biological processes including embryogenesis, cancer metastasis, and wound healing. Spheroid cell aggregate is a particularly interesting model system for the study of these phenomena. In the long time, they behave like drops with a surface tension. In the short, viscoelasticity also needs to be considered. In this work, we discover two coupled and universal timescales for spheroid aggregates. A total of 12 aggregate types (total aggregate number n =290) derived from L and GBM (glioblastoma multiforme) cells are studied with microtensiometer to obtain their surface tension. They are also allowed to relax upon release of the compression forces. The two timescales are observed during the relaxation process; their values do not depend on compression time nor the degree of deformation, and are consistent among all 12 types. Following prior work (Yu et al., Phys. Rev. Lett., 115:128303; Liu et al., J. Mech. Phys. Solids, 98:309-329) we use a rigorous mathematical theory to interpret the results, which reveals intriguing properties of the aggregates on both tissue and cellular levels. The mechanics of multicellular organization reflects both complexity and regularity due to strong active regulation.

  7. Cell survival in spheroids irradiated with heavy-ion beams

    International Nuclear Information System (INIS)

    Rodriguez, A.; Alpen, E.L.

    1981-01-01

    Biological investigations with accelerated heavy ions have been carried out regularly at the Lawrence Berkeley Laboratory Bevalac for the past four years. Most of the cellular investigations have been conducted on cell monolayer and suspension culture systems. The studies to date suggest that heavy charged particle beams may offer some radiotherapeutic advantages over conventional radiotherapy sources. The advantages are thought to lie primarily in an increased relative biological effectiveness (RBE), a decrease in the oxygen enhancement ratio (OER), and better tissue distribution dose. Experiments reported here were conducted with 400 MeV/amu carbon ions and 425 MeV/amu neon ions, using a rat brain gliosarcoma cell line grown as multicellular spheroids. Studies have been carried out with x-rays and high-energy carbon and neon ion beams. These studies evaluate high-LET (linear energy transfer) cell survival in terms of RBE and the possible contributions of intercellular communication. Comparisons were made of the post-irradiation survival characteristics for cells irradiated as multicellular spheroids (approximately 100 μm and 300 μm diameters) and for cells irradiated in suspension. These comparisons were made between 225-kVp x-rays, 400 MeV/amu carbon ions, and 425 MeV/amu neon ions

  8. Two step continuous method to synthesize colloidal spheroid gold nanorods.

    Science.gov (United States)

    Chandra, S; Doran, J; McCormack, S J

    2015-12-01

    This research investigated a two-step continuous process to synthesize colloidal suspension of spheroid gold nanorods. In the first step; gold precursor was reduced to seed-like particles in the presence of polyvinylpyrrolidone and ascorbic acid. In continuous second step; silver nitrate and alkaline sodium hydroxide produced various shape and size Au nanoparticles. The shape was manipulated through weight ratio of ascorbic acid to silver nitrate by varying silver nitrate concentration. The specific weight ratio of 1.35-1.75 grew spheroid gold nanorods of aspect ratio ∼1.85 to ∼2.2. Lower weight ratio of 0.5-1.1 formed spherical nanoparticle. The alkaline medium increased the yield of gold nanorods and reduced reaction time at room temperature. The synthesized gold nanorods retained their shape and size in ethanol. The surface plasmon resonance was red shifted by ∼5 nm due to higher refractive index of ethanol than water. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Oxygen consumption rate and mitochondrial density in human melanoma monolayer cultures and multicellular spheroids.

    Science.gov (United States)

    Hystad, M E; Rofstad, E K

    1994-05-15

    Rate of oxygen consumption per cell has been shown in previous studies to decrease with increasing depth in the viable rim of multicellular spheroids initiated from rodent cells, human colon-carcinoma cells, and human glioma cells, due to progressive accumulation of quiescent cells during spheroid growth. The purpose of our work was to determine oxygen-consumption profiles in human melanoma spheroids. Monolayer cultures of 4 lines (BEX-c, COX-c, SAX-c, and WIX-c) and spheroid cultures of 2 lines (BEX-c and WIX-c) were subjected to investigation. Spheroids were initiated from monolayer cell cultures and grown in spinner flasks. Rate of oxygen consumption was measured with a Clarke-type electrode. Mitochondrial density was determined by stereological analysis of transmission electron micrographs. Thickness of viable rim and cell packing density were assessed by light microscopy of central spheroid sections. Cell-cycle distribution was determined by analysis of DNA histograms measured by flow cytometry. Cell volume was measured by an electronic particle counter. Rate of oxygen consumption per cell differed by a factor of approximately 1.8 between the 4 cell lines and was positively correlated to total volume of mitochondria per cell. Rate of oxygen consumption per cell and total volume of mitochondria per cell were equal for monolayer cell cultures, 600-microns spheroids and 1,200-microns spheroids of the same line. Mitochondrial density and location in the cell did not differ between cells at the spheroid surface, in the middle of the viable rim and adjacent to the central necrosis. Cell-cycle distribution, cell volume, and cell-packing density in the outer and inner halves of the viable rim were not significantly different. Consequently, the rate of oxygen consumption per cell in inner regions of the viable rim was probably equal to that at the spheroid surface, suggesting that oxygen diffusion distances may be shorter in some melanomas than in many other tumor

  10. Coal option. [Shell Co

    Energy Technology Data Exchange (ETDEWEB)

    1978-01-01

    This paper notes the necessity of developing an international coal trade on a very large scale. The role of Shell in the coal industry is examined; the regions in which Shell companies are most active are Australia, Southern Africa, Indonesia; Europe and North America. Research is being carried out on marketing and transportation, especially via slurry pipelines; coal-oil emulsions; briquets; fluidized-bed combustion; recovery of coal from potential waste material; upgrading of low-rank coals; unconventional forms of mining; coal conversion (the Shell/Koppers high-pressure coal gasification process). Techniques for cleaning flue gas (the Shell Flue Gas Desulfurization process) are being examined.

  11. Shell-like structures

    CERN Document Server

    Altenbach, Holm

    2011-01-01

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

  12. UVES Abundances of Stars in Nearby Dwarf Spheroidal Galaxies

    Science.gov (United States)

    Tolstoy, Eline; Venn, Kim; Shetrone, Matt; Primas, Francesca; Hill, Vanessa; Kaufer, Andreas; Szeifert, Thomas

    2002-07-01

    It is a truth universally acknowledged, that a galaxy in possession of a good quantity of gas must want to form stars. It is the details of how and why that baffle us all. The simplest theories either would have this process a carefully self-regulated affair, or one that goes completely out of control and is capable of wrecking the galaxy which hosts it. Of course the majority of galaxies seem to amble along somewhere between these two extremes, and the mean properties tend to favour a quiescent self-regulated evolutionary scenario. But there area variety of observations which require us to invoke transitory ‘bursts’ of star-formation at one time or another in most galaxy types. Several nearby dwarf spheroidal galaxies have clearly determined star-formation histories with apparent periods of zero star formation followed by periods of fairly active star formation. If we are able to understand what separated these bursts we would understand several important phenomena in galaxy evolution. Were these galaxies able to clear out their gas reservoir in a burst of star formation? How did this gas return? or did it? Have these galaxies receieved gas from the IGM instead? Could stars from these types of galaxy contribute significantly to the halo population in our Galaxy? To answer these questions we need to combine accurate stellar photometry and Colour-Magnitude Diagram interpretation with detailed metal abundances to combine a star-formation rate versus time with a range of element abundances with time. Different elements trace different evolutionary process (e.g., relative contributions of type I and II supernovae). We often aren't even sure of the abundance spread in these galaxies. We have collected detailed high resolution UVES spectra of four nearby dwarf spheroidal galaxies (Sculptor, Fornax, Leo I & Carina) to begin to answer these questions. This is a precursor study to a more complete study with FLAMES. We presented at this meeting the initial results for

  13. Hypersonic vibrations of Ag@SiO2 (cubic core)-shell nanospheres.

    Science.gov (United States)

    Sun, Jing Ya; Wang, Zhi Kui; Lim, Hock Siah; Ng, Ser Choon; Kuok, Meng Hau; Tran, Toan Trong; Lu, Xianmao

    2010-12-28

    The intriguing optical and catalytic properties of metal-silica core-shell nanoparticles, inherited from their plasmonic metallic cores together with the rich surface chemistry and increased stability offered by their silica shells, have enabled a wide variety of applications. In this work, we investigate the confined vibrational modes of a series of monodisperse Ag@SiO(2) (cubic core)-shell nanospheres synthesized using a modified Stöber sol-gel method. The particle-size dependence of their mode frequencies has been mapped by Brillouin light scattering, a powerful tool for probing hypersonic vibrations. Unlike the larger particles, the observed spheroidal-like mode frequencies of the smaller ones do not scale with inverse diameter. Interestingly, the onset of the deviation from this linearity occurs at a smaller particle size for higher-energy modes than for lower-energy ones. Finite element simulations show that the mode displacement profiles of the Ag@SiO(2) core-shells closely resemble those of a homogeneous SiO(2) sphere. Simulations have also been performed to ascertain the effects that the core shape and the relative hardness of the core and shell materials have on the vibrations of the core-shell as a whole. As the vibrational modes of a particle have a bearing on its thermal and mechanical properties, the findings would be of value in designing core-shell nanostructures with customized thermal and mechanical characteristics.

  14. Proteomic approach toward molecular backgrounds of drug resistance of osteosarcoma cells in spheroid culture system.

    Science.gov (United States)

    Arai, Kazuya; Sakamoto, Ruriko; Kubota, Daisuke; Kondo, Tadashi

    2013-08-01

    Chemoresistance is one of the most critical prognostic factors in osteosarcoma, and elucidation of the molecular backgrounds of chemoresistance may lead to better clinical outcomes. Spheroid cells resemble in vivo cells and are considered an in vitro model for the drug discovery. We found that spheroid cells displayed more chemoresistance than conventional monolayer cells across 11 osteosarcoma cell lines. To investigate the molecular mechanisms underlying the resistance to chemotherapy, we examined the proteomic differences between the monolayer and spheroid cells by 2D-DIGE. Of the 4762 protein species observed, we further investigated 435 species with annotated mass spectra in the public proteome database, Genome Medicine Database of Japan Proteomics. Among the 435 protein species, we found that 17 species exhibited expression level differences when the cells formed spheroids in more than five cell lines and four species out of these 17 were associated with spheroid-formation associated resistance to doxorubicin. We confirmed the upregulation of cathepsin D in spheroid cells by western blotting. Cathepsin D has been implicated in chemoresistance of various malignancies but has not previously been implemented in osteosarcoma. Our study suggested that the spheroid system may be a useful tool to reveal the molecular backgrounds of chemoresistance in osteosarcoma. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Detachably assembled microfluidic device for perfusion culture and post-culture analysis of a spheroid array.

    Science.gov (United States)

    Sakai, Yusuke; Hattori, Koji; Yanagawa, Fumiki; Sugiura, Shinji; Kanamori, Toshiyuki; Nakazawa, Kohji

    2014-07-01

    Microfluidic devices permit perfusion culture of three-dimensional (3D) tissue, mimicking the flow of blood in vascularized 3D tissue in our body. Here, we report a microfluidic device composed of a two-part microfluidic chamber chip and multi-microwell array chip able to be disassembled at the culture endpoint. Within the microfluidic chamber, an array of 3D tissue aggregates (spheroids) can be formed and cultured under perfusion. Subsequently, detailed post-culture analysis of the spheroids collected from the disassembled device can be performed. This device facilitates uniform spheroid formation, growth analysis in a high-throughput format, controlled proliferation via perfusion flow rate, and post-culture analysis of spheroids. We used the device to culture spheroids of human hepatocellular carcinoma (HepG2) cells under two controlled perfusion flow rates. HepG2 spheroids exhibited greater cell growth at higher perfusion flow rates than at lower perfusion flow rates, and exhibited different metabolic activity and mRNA and protein expression under the different flow rate conditions. These results show the potential of perfusion culture to precisely control the culture environment in microfluidic devices. The construction of spheroid array chambers allows multiple culture conditions to be tested simultaneously, with potential applications in toxicity and drug screening. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. An injectable spheroid system with genetic modification for cell transplantation therapy.

    Science.gov (United States)

    Uchida, Satoshi; Itaka, Keiji; Nomoto, Takahiro; Endo, Taisuke; Matsumoto, Yu; Ishii, Takehiko; Kataoka, Kazunori

    2014-03-01

    The new methodology to increase a therapeutic potential of cell transplantation was developed here by the use of three-dimensional spheroids of transplanting cells subsequent to the genetic modification with non-viral DNA vectors, polyplex nanomicelles. Particularly, spheroids in regulated size of 100-μm of primary hepatocytes transfected with luciferase gene were formed on the micropatterned culture plates coated with thermosensitive polymer, and were recovered in the form of injectable liquid suspension simply by cooling the plates. After subcutaneously transplanting these hepatocyte spheroids, efficient transgene expression was observed in host tissue for more than a month, whereas transplantation of a single-cell suspension from a monolayer culture resulted in an only transient expression. The spheroid system contributed to the preservation of innate functions of transplanted hepatocytes in the host tissue, such as albumin expression, thereby possessing high potential for expressing transgene. Intravital observation of transplanted cells showed that those from spheroid cultures had a tendency to localize in the vicinity of blood vessels, making a favorable microenvironment for preserving cell functionality. Furthermore, spheroids transfected with erythropoietin-expressing DNA showed a significantly higher hematopoietic effect than that of cell suspensions from monolayer cultures, demonstrating high potential of this genetically-modified spheroid transplantation system for therapeutic applications. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. Identification of Lgr5-Independent Spheroid-Generating Progenitors of the Mouse Fetal Intestinal Epithelium

    Directory of Open Access Journals (Sweden)

    Roxana C. Mustata

    2013-10-01

    Full Text Available Immortal spheroids were generated from fetal mouse intestine using the culture system initially developed to culture organoids from adult intestinal epithelium. Spheroid proportion progressively decreases from fetal to postnatal period, with a corresponding increase in production of organoids. Like organoids, spheroids show Wnt-dependent indefinite self-renewing properties but display a poorly differentiated phenotype reminiscent of incompletely caudalized progenitors. The spheroid transcriptome is strikingly different from that of adult intestinal stem cells, with minimal overlap of Wnt target gene expression. The receptor LGR4, but not LGR5, is essential for their growth. Trop2/Tacstd2 and Cnx43/Gja1, two markers highly enriched in spheroids, are expressed throughout the embryonic-day-14 intestinal epithelium. Comparison of in utero and neonatal lineage tracing using Cnx43-CreER and Lgr5-CreERT2 mice identified spheroid-generating cells as developmental progenitors involved in generation of the prenatal intestinal epithelium. Ex vivo, spheroid cells have the potential to differentiate into organoids, qualifying as a fetal type of intestinal stem cell.

  18. Promotion of malignant phenotype after disruption of the three-dimensional structure of cultured spheroids from colorectal cancer.

    Science.gov (United States)

    Piulats, Jose M; Kondo, Jumpei; Endo, Hiroko; Ono, Hiromasa; Hagihara, Takeshi; Okuyama, Hiroaki; Nishizawa, Yasuko; Tomita, Yasuhiko; Ohue, Masayuki; Okita, Kouki; Oyama, Hidejiro; Bono, Hidemasa; Masuko, Takashi; Inoue, Masahiro

    2018-03-23

    Individual and small clusters of cancer cells may detach from the edges of a main tumor and invade vessels, which can act as the origin of metastasis; however, the mechanism for this phenomenon is not well understood. Using cancer tissue-originated spheroids, we studied whether disturbing the 3D architecture of cancer spheroids can provoke the reformation process and progression of malignancy. We developed a mechanical disruption method to achieve homogenous disruption of the spheroids while maintaining cell-cell contact. After the disruption, 9 spheroid lines from 9 patient samples reformed within a few hours, and 3 of the 9 lines exhibited accelerated spheroid growth. Marker expression, spheroid forming capacity, and tumorigenesis indicated that stemness increased after spheroid disruption. In addition, the spheroid forming capacity increased in 6 of 11 spheroid lines. The disruption signature determined by gene expression profiling supported the incidence of remodeling and predicted the prognosis of patients with colorectal cancer. Furthermore, WNT and HER3 signaling were increased in the reformed spheroids, and suppression of these signaling pathways attenuated the increased proliferation and stemness after the disruption. Overall, the disruption and subsequent reformation of cancer spheroids promoted malignancy-related phenotypes through the activation of the WNT and ERBB pathways.

  19. Pervasive plastisphere: First record of plastics in egagropiles (Posidonia spheroids).

    Science.gov (United States)

    Pietrelli, Loris; Di Gennaro, Alessia; Menegoni, Patrizia; Lecce, Francesca; Poeta, Gianluca; Acosta, Alicia T R; Battisti, Corrado; Iannilli, Valentina

    2017-10-01

    The ability of Posidonia oceanica spheroids (egagropiles, EG) to incorporate plastics was investigated along the central Italy coast. Plastics were found in the 52.84% of the egagropiles collected (n = 685). The more represented size of plastics has range within 1-1.5 cm, comparable to the size of natural fibres. Comparing plastics occurring both in EG and in surrounding sand, Polyethylene, Polyester and Nylon were the most abundant polymers in EG, while PSE, PE, PP and PET were the most represented in sand. In particular PE and PP were significantly more represented in sand, while PE, Nylon, Polyester and microfibers (as pills) were more represented in EG. Within plastics found in EG, 26.9% were microfibers as small pills (PET mixing. These microfibers might be produced by discharges from washing machines and currently represents an emerging pollutant with widespread distribution in marine and freshwater ecosystems. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Modes of spheroidal ion plasmas at the Brillouin limit

    International Nuclear Information System (INIS)

    Tinkle, M.D.; Greaves, R.G.; Surko, C.M.

    1996-01-01

    The confinement properties and collective modes of single-component plasmas are investigated in a quadrupole Penning trap. Brillouin-density pure ion plasmas are generated by electron-beam ionization of a low-pressure gas. Large, spheroidal, steady-state plasmas are produced, extending out to contact one or more of the trap electrodes. With the density fixed at the Brillouin limit by the high ion production rate, the electrode potentials determine the plasma shape. The frequencies of azimuthally propagating cyclotron and diocotron modes are found to vary significantly with the plasma aspect ratio. For oblate plasmas, the frequencies are in good agreement with a simple fluid model. copyright 1996 American Institute of Physics

  1. Patient-specific three-dimensional explant spheroids derived from human nasal airway epithelium

    DEFF Research Database (Denmark)

    Marthin, June Kehlet; Stevens, Elizabeth Munkebjerg; Larsen, Lars Allan

    2017-01-01

    BACKGROUND: Three-dimensional explant spheroid formation is an ex vivo technique previously used in studies of airway epithelial ion and water transport. Explanted cells and sheets of nasal epithelium form fully differentiated spheroids enclosing a partly fluid-filled lumen with the ciliated apical...... surface facing the outside and accessible for analysis of ciliary function. METHODS: We performed a two-group comparison study of ciliary beat pattern and ciliary beat frequency in spheroids derived from nasal airway epithelium in patients with primary ciliary dyskinesia (PCD) and in healthy controls...... in the investigation of pathophysiological aspects and drug effects in human nasal airway epithelium....

  2. Scattering of a high-order Bessel beam by a spheroidal particle

    Science.gov (United States)

    Han, Lu

    2018-05-01

    Within the framework of generalized Lorenz-Mie theory (GLMT), scattering from a homogeneous spheroidal particle illuminated by a high-order Bessel beam is formulated analytically. The high-order Bessel beam is expanded in terms of spheroidal vector wave functions, where the spheroidal beam shape coefficients (BSCs) are computed conveniently using an intrinsic method. Numerical results concerning scattered field in the far zone are displayed for various parameters of the incident Bessel beam and of the scatter. These results are expected to provide useful insights into the scattering of a Bessel beam by nonspherical particles and particle manipulation applications using Bessel beams.

  3. A theoretical study of hot plasma spheroids in the presence of low-frequency electromagnetic waves

    Science.gov (United States)

    Ahmadizadeh, Y.; Jazi, B.; Barjesteh, S.

    2016-07-01

    While taking into account thermal motion of electrons, scattering of electromagnetic waves with low frequency from hot plasma spheroids is investigated. In this theoretical research, ions are heavy to respond to electromagnetic fluctuations. The solution of scalar wave equation in spheroidal coordinates for electric potential inside the plasma spheroids are obtained. The variations of resonance frequencies vs. Debye length are studied and consistency between the obtained results in this paper and the results for the well-known plasma objects such as plasma column and spherical plasma have been proved.

  4. Low-temperature plasma spheroidizing of polydisperse powders of refractory materials

    International Nuclear Information System (INIS)

    Tsymbalist, M.M.; Rudenskaya, N.A.; Kuz'min, B.P.; Pan'kov, V.A.

    2003-01-01

    A model is developed for heating and melting of a spherical particle, when powder processing in low temperature plasma, with the aim of estimation of the dependence of the degree of fusion on particle size for various materials. Spheroidizing of various refractory material powders close in shape and size composition is experimentally performed. Experimental and calculation estimates of spheroidizing criteria for the materials studied are in a satisfactory agreement. The influence of basic physical properties of refractory materials and plasma processing parameters on the degree of particle spheroidizing is analyzed [ru

  5. Multicellular tumor spheroid interactions with bone cells and bone

    International Nuclear Information System (INIS)

    Wezeman, F.H.; Guzzino, K.M.; Waxler, B.

    1985-01-01

    In vitro coculture techniques were used to study HSDM1C1 murine fibrosarcoma multicellular tumor spheroid (HSDM1C1-MTS) interactions with mouse calvarial bone cells having osteoblastic characteristics and mouse bone explants. HSDM1C1-MTS attached to confluent bone cell monolayers and their attachment rate was quantified. HSDM1C1-MTS interaction with bone cells was further demonstrated by the release of 3 H-deoxyuridine from prelabeled bone cells during coculture with multicellular tumor spheroids. HSDM1C1-MTS-induced cytotoxicity was mimicked by the addition of 10(-5) M prostaglandin E2 (PGE2) to 3 H-deoxyuridine-labeled bone cells. The effects of low (10(-9) M) and high (10(-5) M) concentrations of PGE2 on bone cell proliferation were also studied. Higher concentrations of PGE2 inhibited bone cell proliferation. HSDM1C1-MTS resorbed living explants in the presence of indomethacin, suggesting that other tumor cell products may also participate in bone resorption. HSDM1C1-MTS caused direct bone resorption as measured by the significantly elevated release of 45 Ca from prelabeled, devitalized calvaria. However, the growth of a confluent bone cell layer on devitalized, 45 Ca-prelabeled calvaria resulted in a significant reduction in the amount of 45 Ca released subsequent to the seeding of HSDM1C1-MTS onto the explants. Bone cells at the bone surface may act as a barrier against invasion and tumor cell-mediated bone resorption. Violation of this cellular barrier is achieved, in part, by tumor cell products

  6. Tensile Forces Originating from Cancer Spheroids Facilitate Tumor Invasion.

    Directory of Open Access Journals (Sweden)

    Katarzyna S Kopanska

    Full Text Available The mechanical properties of tumors and the tumor environment provide important information for the progression and characterization of cancer. Tumors are surrounded by an extracellular matrix (ECM dominated by collagen I. The geometrical and mechanical properties of the ECM play an important role for the initial step in the formation of metastasis, presented by the migration of malignant cells towards new settlements as well as the vascular and lymphatic system. The extent of this cell invasion into the ECM is a key medical marker for cancer prognosis. In vivo studies reveal an increased stiffness and different architecture of tumor tissue when compared to its healthy counterparts. The observed parallel collagen organization on the tumor border and radial arrangement at the invasion zone has raised the question about the mechanisms organizing these structures. Here we study the effect of contractile forces originated from model tumor spheroids embedded in a biomimetic collagen I matrix. We show that contractile forces act immediately after seeding and deform the ECM, thus leading to tensile radial forces within the matrix. Relaxation of this tension via cutting the collagen does reduce invasion, showing a mechanical relation between the tensile state of the ECM and invasion. In turn, these results suggest that tensile forces in the ECM facilitate invasion. Furthermore, simultaneous contraction of the ECM and tumor growth leads to the condensation and reorientation of the collagen at the spheroid's surface. We propose a tension-based model to explain the collagen organization and the onset of invasion by forces originating from the tumor.

  7. Shell coal gasification process

    Energy Technology Data Exchange (ETDEWEB)

    Hennekes, B. [Shell Global Solutions (US) Inc. (United States). Technology Marketing

    2002-07-01

    The presentation, on which 17 slides/overheads are included in the papers, explained the principles of the Shell coal gasification process and the methods incorporated for control of sulfur dioxide, nitrogen oxides, particulates and mercury. The economics of the process were discussed. The differences between gasification and burning, and the differences between the Shell process and other processes were discussed.

  8. Wrinkling of Pressurized Elastic Shells

    KAUST Repository

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

    2011-01-01

    We study the formation of localized structures formed by the point loading of an internally pressurized elastic shell. While unpressurized shells (such as a ping-pong ball) buckle into polygonal structures, we show that pressurized shells

  9. Study of human prostate spheroids treated with zinc using X-ray microfluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Leitao, Roberta G.; Lopes, Ricardo T.; Pereira, Gabriela R., E-mail: roberta@lin.ufrj.br, E-mail: gpereira@metalmat.ufrj.br [Coordenacao dos Cursos de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil); Santos, Carlos A.N., E-mail: cansantos.bio@gmail.com [Instituto Nacional de Metrologia, Qualidade e Tecnologia (DIPRO/INMETRO), Duque de Caxias, RJ (Brazil). Lab. de Biotecnologia; Palumbo Junior, Antonio; Nasciutti, Luiz E., E-mail: nasciutt@ufrj.br [Universidade Federal do Rio de Janeiro (ICB/CCS/UFRJ), Rio de Janeiro, RJ (Brazil). Lab. de Interacoes Celulares; Souza, Pedro A.V.R., E-mail: pedroaugustoreis@uol.com.br [Hospital Federal do Andarai (HFA), Rio de Janeiro, RJ (Brazil). Servico de Urologia; Anjos, Marcelino J., E-mail: marcelin@lin.ufrj.br [Universidade Estatual do Rio de Janeiro (UERJ), Rio de Janeiro, RJ (Brazil). Inst. de Fisica

    2013-07-01

    Spheroids cell culture is a useful technique for tissue engineering or regenerative medicine re-search, pharmacological and toxicological studies, and fundamental studies in cell biology. In this study, we investigated Zn distribution in cell spheroids in benign prostate hyperplasia (BPH) and prostate cancer (DU145) and analyzed the differences in the response to Zinc (0-150 μM) treatment. The measurements were performed in standard geometry of 45 deg incidence, exciting with a white beam and using an optical capillary with 20 μm diameter collimation in the XRF beam line at the Synchrotron Light National Laboratory (Campinas, Brazil). The results showed non-uniform distribution of Zn in all the spheroids analyzed. The differential response to zinc of DU145 and BPH cell spheroids suggests that zinc may have an important role in prostate cancer and BPH diagnosis. (author)

  10. Axonal Spheroid Accumulation In the Brainstem and Spinal Cord of A Young Angus Cow with Ataxia.

    Science.gov (United States)

    Hanshaw, D M; Finnie, J W; Manavis, J; Kessell, A E

    2015-08-01

    An 18-month-old Angus cow presented with rapidly developing ataxia and subsequently died. The finding of large numbers of axonal spheroids in brainstem nuclei and spinal cord grey matter, bilaterally symmetrical in distribution, was consistent with a histopathological diagnosis of neuroaxonal dystrophy (NAD). Most of the axonal swellings were immunopositive to amyloid precursor protein, suggesting that interruption to axonal flow was important in their genesis. The topographical distribution of axonal spheroids in the brain and spinal cord in this bovine case closely resembled that found in the ovine neurodegenerative disorder termed NAD, in which axonal swellings are the major pathological feature. This appears to be the first reported case of this type of NAD in cattle. The aetiology of the spheroidal aggregations in this case was not determined. There was no evidence from the case history or neuropathology to indicate whether the axonal spheroids in this case involved an acquired or heritable aetiology. © 2015 Australian Veterinary Association.

  11. Processes of Formation of Spheroidal Concretions and Inferences for "Blueberries" in Meridiani Planum Sediments

    Science.gov (United States)

    Coleman, M. L.

    2005-03-01

    Formation of spheroidal concretions on Earth results generally from reactions of organic matter in oxidized sediments. Had organic matter been present in Merididani Planum it could have produced a reduced iron mineral phase later oxidized to hematite.

  12. Study of human prostate spheroids treated with zinc using X-ray microfluorescence

    International Nuclear Information System (INIS)

    Leitao, Roberta G.; Lopes, Ricardo T.; Pereira, Gabriela R.; Santos, Carlos A.N.; Palumbo Junior, Antonio; Nasciutti, Luiz E.; Souza, Pedro A.V.R.; Anjos, Marcelino J.

    2013-01-01

    Spheroids cell culture is a useful technique for tissue engineering or regenerative medicine re-search, pharmacological and toxicological studies, and fundamental studies in cell biology. In this study, we investigated Zn distribution in cell spheroids in benign prostate hyperplasia (BPH) and prostate cancer (DU145) and analyzed the differences in the response to Zinc (0-150 μM) treatment. The measurements were performed in standard geometry of 45 deg incidence, exciting with a white beam and using an optical capillary with 20 μm diameter collimation in the XRF beam line at the Synchrotron Light National Laboratory (Campinas, Brazil). The results showed non-uniform distribution of Zn in all the spheroids analyzed. The differential response to zinc of DU145 and BPH cell spheroids suggests that zinc may have an important role in prostate cancer and BPH diagnosis. (author)

  13. Repair, redistribution and repopulation in V79 spheroids during multifraction irradiation

    International Nuclear Information System (INIS)

    Brown, R.C.; Durand, R.E.

    1994-01-01

    We used cells growing as multicell spheroids to determine whether the initial radiation response would be predictive for multifraction exposures, or whether other factors including repopulation rate should be considered. Potential problems of hypoxia and reoxygenation were avoided by using small spheroids which had not yet developed radiobiologically hypoxic regions. Repair and redistribution dominated the responses in the first two or three exposures, with repopulation playing a minor role. As the fractionation schedule was extended, however, repopulation between fractions largely determined the number of viable cells per spheroid. We conclude that the radiation response of cells from untreated spheroids provides a general indication of net sensitivity, but that repair and redistribution produces considerable variation in radiosensitivity throughout a fractionation protocol. Ultimately, repopulation effects may dominate the multifraction response. (Author)

  14. Direct Measurements of Oxygen Gradients in Spheroid Culture System Using Electron Parametric Resonance Oximetry.

    Directory of Open Access Journals (Sweden)

    Laura M Langan

    Full Text Available Advanced in vitro culture from tissues of different origin includes three-dimensional (3D organoid micro structures that may mimic conditions in vivo. One example of simple 3D culture is spheroids; ball shaped structures typically used as liver and tumour models. Oxygen is critically important in physiological processes, but is difficult to quantify in 3D culture: and the question arises, how small does a spheroid have to be to have minimal micro-environment formation? This question is of particular importance in the growing field of 3D based models for toxicological assessment. Here, we describe a simple non-invasive approach modified for the quantitative measurement and subsequent evaluation of oxygen gradients in spheroids developed from a non-malignant fish cell line (i.e. RTG-2 cells using Electron Paramagnetic Resonance (EPR oximetry. Sonication of the paramagnetic probe Lithium phthalocyanine (LiPc allows for incorporation of probe particulates into spheroid during its formation. Spectra signal strength after incorporation of probe into spheroid indicated that a volume of 20 μl of probe (stock solution: 0.10 mg/mL is sufficient to provide a strong spectra across a range of spheroid sizes. The addition of non-toxic probes (that do not produce or consume oxygen report on oxygen diffusion throughout the spheroid as a function of size. We provide evidence supporting the use of this model over a range of initial cell seeding densities and spheroid sizes with the production of oxygen distribution as a function of these parameters. In our spheroid model, lower cell seeding densities (∼2,500 cells/spheroid and absolute size (118±32 μm allow control of factors such as pre-existing stresses (e.g. ∼ 2% normoxic/hypoxic interface for more accurate measurement of treatment response. The applied methodology provides an elegant, widely applicable approach to directly characterize spheroid (and other organoid cultures in biomedical and

  15. Molluscan shell colour.

    Science.gov (United States)

    Williams, Suzanne T

    2017-05-01

    The phylum Mollusca is highly speciose, and is the largest phylum in the marine realm. The great majority of molluscs are shelled, including nearly all bivalves, most gastropods and some cephalopods. The fabulous and diverse colours and patterns of molluscan shells are widely recognised and have been appreciated for hundreds of years by collectors and scientists alike. They serve taxonomists as characters that can be used to recognise and distinguish species, however their function for the animal is sometimes less clear and has been the focus of many ecological and evolutionary studies. Despite these studies, almost nothing is known about the evolution of colour in molluscan shells. This review summarises for the first time major findings of disparate studies relevant to the evolution of shell colour in Mollusca and discusses the importance of colour, including the effects of visual and non-visual selection, diet and abiotic factors. I also summarise the evidence for the heritability of shell colour in some taxa and recent efforts to understand the molecular mechanisms underpinning synthesis of shell colours. I describe some of the main shell pigments found in Mollusca (carotenoids, melanin and tetrapyrroles, including porphyrins and bile pigments), and their durability in the fossil record. Finally I suggest that pigments appear to be distributed in a phylogenetically relevant manner and that the synthesis of colour is likely to be energetically costly. © 2016 Cambridge Philosophical Society.

  16. Shell structure and orbit bifurcations in finite fermion systems

    Science.gov (United States)

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

    2011-10-01

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

  17. Theory of electrostatic fluid modes in a cold spheroidal non-neutral plasma

    International Nuclear Information System (INIS)

    Dubin, D.H.E.

    1991-01-01

    The normal modes of a magnetized spheroidally shaped pure ion plasma have recently been measured. Here the theory of these modes is presented. Although one might expect that a numerical solution is required (because the plasma dielectric is anisotropic and the plasma is inhomogeneous), the problem is actually separable in an unusual coordinate system. The result is a simple electrostatic fluid dispersion relation for modes in a cloud of any spheroidal shape

  18. Radioresistance of human glioma spheroids and expression of HSP70, p53 and EGFr

    International Nuclear Information System (INIS)

    Fedrigo, Carlos A; Rocha, Adriana B da; Grivicich, Ivana; Schunemann, Daniel P; Chemale, Ivan M; Santos, Daiane dos; Jacovas, Thais; Boschetti, Patryck S; Jotz, Geraldo P; Filho, Aroldo Braga

    2011-01-01

    Radiation therapy is routinely prescribed for high-grade malignant gliomas. However, the efficacy of this therapeutic modality is often limited by the occurrence of radioresistance, reflected as a diminished susceptibility of the irradiated cells to undergo cell death. Thus, cells have evolved an elegant system in response to ionizing radiation induced DNA damage, where p53, Hsp70 and/or EGFr may play an important role in the process. In the present study, we investigated whether the content of p53, Hsp70 and EGFr are associated to glioblastoma (GBM) cell radioresistance. Spheroids from U-87MG and MO59J cell lines as well as spheroids derived from primary culture of tumor tissue of one GBM patient (UGBM1) were irradiated (5, 10 and 20 Gy), their relative radioresistance were established and the p53, Hsp70 and EGFr contents were immunohistochemically determined. Moreover, we investigated whether EGFr-phospho-Akt and EGFr-MEK-ERK pathways can induce GBM radioresistance using inhibitors of activation of ERK (PD098059) and Akt (wortmannin). At 5 Gy irradiation UGBM1 and U-87MG spheroids showed growth inhibition whereas the MO59J spheroid was relatively radioresistant. Overall, no significant changes in p53 and Hsp70 expression were found following 5 Gy irradiation treatment in all spheroids studied. The only difference observed in Hsp70 content was the periphery distribution in MO59J spheroids. However, 5 Gy treatment induced a significant increase on the EGFr levels in MO59J spheroids. Furthermore, treatment with inhibitors of activation of ERK (PD098059) and Akt (wortmannin) leads to radiosensitization of MO59J spheroids. These results indicate that the PI3K-Akt and MEK-ERK pathways triggered by EGFr confer GBM radioresistance

  19. Rapid formation of size-controllable multicellular spheroids via 3D acoustic tweezers.

    Science.gov (United States)

    Chen, Kejie; Wu, Mengxi; Guo, Feng; Li, Peng; Chan, Chung Yu; Mao, Zhangming; Li, Sixing; Ren, Liqiang; Zhang, Rui; Huang, Tony Jun

    2016-07-05

    The multicellular spheroid is an important 3D cell culture model for drug screening, tissue engineering, and fundamental biological research. Although several spheroid formation methods have been reported, the field still lacks high-throughput and simple fabrication methods to accelerate its adoption in drug development industry. Surface acoustic wave (SAW) based cell manipulation methods, which are known to be non-invasive, flexible, and high-throughput, have not been successfully developed for fabricating 3D cell assemblies or spheroids, due to the limited understanding on SAW-based vertical levitation. In this work, we demonstrated the capability of fabricating multicellular spheroids in the 3D acoustic tweezers platform. Our method used drag force from microstreaming to levitate cells in the vertical direction, and used radiation force from Gor'kov potential to aggregate cells in the horizontal plane. After optimizing the device geometry and input power, we demonstrated the rapid and high-throughput nature of our method by continuously fabricating more than 150 size-controllable spheroids and transferring them to Petri dishes every 30 minutes. The spheroids fabricated by our 3D acoustic tweezers can be cultured for a week with good cell viability. We further demonstrated that spheroids fabricated by this method could be used for drug testing. Unlike the 2D monolayer model, HepG2 spheroids fabricated by the 3D acoustic tweezers manifested distinct drug resistance, which matched existing reports. The 3D acoustic tweezers based method can serve as a novel bio-manufacturing tool to fabricate complex 3D cell assembles for biological research, tissue engineering, and drug development.

  20. Rapid formation of size-controllable multicellular spheroids via 3D acoustic tweezers

    OpenAIRE

    Chen, Kejie; Wu, Mengxi; Guo, Feng; Li, Peng; Chan, Chung-Yu; Mao, Zhangming; Li, Sixing; Ren, Liqiang; Zhang, Rui; Huang, Tony Jun

    2016-01-01

    The multicellular spheroid is an important 3D cell culture model for drug screening, tissue engineering, and fundamental biological research. Although several spheroid formation methods have been reported, the field still lacks high-throughput and simple fabrication methods to accelerate its adoption in drug development industry. Surface acoustic wave (SAW) based cell manipulation methods, which are known to be non-invasive, flexible, and high-throughput, have not been successfully developed ...

  1. Nuclear shell theory

    CERN Document Server

    de-Shalit, Amos; Massey, H S W

    1963-01-01

    Nuclear Shell Theory is a comprehensive textbook dealing with modern methods of the nuclear shell model. This book deals with the mathematical theory of a system of Fermions in a central field. It is divided into three parts. Part I discusses the single particle shell model. The second part focuses on the tensor algebra, two-particle systems. The last part covers three or more particle systems. Chapters on wave functions in a central field, tensor fields, and the m-Scheme are also presented. Physicists, graduate students, and teachers of nuclear physics will find the book invaluable.

  2. Type II shell evolution in A=70 isobars from the N≥40 island of inversion

    Directory of Open Access Journals (Sweden)

    A.I. Morales

    2017-02-01

    Full Text Available The level structures of 70Co and 70Ni, populated from the β decay of 70Fe, have been investigated using β-delayed γ-ray spectroscopy following in-flight fission of a 238U beam. The experimental results are compared to Monte-Carlo Shell-Model calculations including the pf+g9/2+d5/2 orbitals. The strong population of a (1+ state at 274 keV in 70Co is at variance with the expected excitation energy of ∼1 MeV from near spherical single-particle estimates. This observation indicates a dominance of prolate-deformed intruder configurations in the low-lying levels, which coexist with the normal near spherical states. It is shown that the β decay of the neutron-rich A=70 isobars from the new island of inversion to the Z=28 closed-shell regime progresses in accordance with a newly reported type of shell evolution, the so-called Type II, which involves many particle-hole excitations across energy gaps.

  3. High-throughput image analysis of tumor spheroids: a user-friendly software application to measure the size of spheroids automatically and accurately.

    Science.gov (United States)

    Chen, Wenjin; Wong, Chung; Vosburgh, Evan; Levine, Arnold J; Foran, David J; Xu, Eugenia Y

    2014-07-08

    The increasing number of applications of three-dimensional (3D) tumor spheroids as an in vitro model for drug discovery requires their adaptation to large-scale screening formats in every step of a drug screen, including large-scale image analysis. Currently there is no ready-to-use and free image analysis software to meet this large-scale format. Most existing methods involve manually drawing the length and width of the imaged 3D spheroids, which is a tedious and time-consuming process. This study presents a high-throughput image analysis software application - SpheroidSizer, which measures the major and minor axial length of the imaged 3D tumor spheroids automatically and accurately; calculates the volume of each individual 3D tumor spheroid; then outputs the results in two different forms in spreadsheets for easy manipulations in the subsequent data analysis. The main advantage of this software is its powerful image analysis application that is adapted for large numbers of images. It provides high-throughput computation and quality-control workflow. The estimated time to process 1,000 images is about 15 min on a minimally configured laptop, or around 1 min on a multi-core performance workstation. The graphical user interface (GUI) is also designed for easy quality control, and users can manually override the computer results. The key method used in this software is adapted from the active contour algorithm, also known as Snakes, which is especially suitable for images with uneven illumination and noisy background that often plagues automated imaging processing in high-throughput screens. The complimentary "Manual Initialize" and "Hand Draw" tools provide the flexibility to SpheroidSizer in dealing with various types of spheroids and diverse quality images. This high-throughput image analysis software remarkably reduces labor and speeds up the analysis process. Implementing this software is beneficial for 3D tumor spheroids to become a routine in vitro model

  4. Hypoxic fraction and binding of misonidazole in EMT6/Ed multicellular tumor spheroids

    International Nuclear Information System (INIS)

    Franko, A.J.

    1985-01-01

    Misonidazole has been shown to bind selectively to hypoxic cells in tissue culture and to cells which are presumed to be chronically hypoxic in EMT6 spheroids and tumors. Thus it has considerable potential as a marker of hypoxic cells in vivo. To further evaluate this potential EMT6/Ed spheroids were used to quantitate misonidazole binding under conditions which resulted in hypoxic fractions between 0 and 1. The patterns of binding of 14 C-labeled misonidazole determined by autoradiography were consistent with the regions of radiobiological hypoxia as predicted by oxygen diffusion theory. The overall uptake of 3 H-labeled misonidazole by spheroids correlated well with the hypoxic fraction, although binding to aerobic cells and necrotic tissue contributed appreciably to the total label in the spheroids. It is concluded that misonidazole is an excellent marker of hypoxia in EMT6/Ed spheroids at the microscopic level, and the total amount bound per spheroid provides a potentially useful measure of the hypoxic fraction

  5. The effect of spheroidizing by thermal cycling in low concentration Cr-Mo alloy steel

    International Nuclear Information System (INIS)

    Yun, H.S.; Kang, C.Y.

    1979-01-01

    An intensive study was carried out on spheroidizing of pearlite (Sph) and number of spherical carbide in proeutectoid ferrite (No/100) of low concentration Cr-Mo steel with thermal cycling. Physical and mechanical properties of steel containing 0.33 % C with thermal cycling were compared with those of low concentration Cr-Mo steel with thermal cycling. The effect of normal heat treatment and cooling rate on spheroidizing of pearlite and precipitation of fine spherical carbide in the steels were investigated. The results obtained were as follows: 1) Thermal cycling of low concentration Cr-Mo steel promoted the spheroidizing of pearlite compared with that of steel without Cr and Mo to steel had significant effect on spheroidizing of pearlite. 2) Number of fine spherical carbides of low concentration Cr-Mo steel with thermal cycling was over 5 times to that of fine spherical carbides of hypoeutectoid steel with thermal cycling. 3) Spheroidizing of pearlite and number of fine spherical carbide in proeutectoid ferrite of low concentration Cr-Mo steel with increasing thermal cycle and cooling rate. 4) Hardness of steel with thermal cycling was decreased. However, low concentration Cr-Mo steel had little decreasing rate in hardness with increasing thermal cycle on the basis of 100 times in thermal cycle. Therefore, toughness was considered to be increased with increasing spheroidizing of pearlite without changing mechanical properties. (author)

  6. Cancer cell spheroids are a better screen for the photodynamic efficiency of glycosylated photosensitizers.

    Directory of Open Access Journals (Sweden)

    Patrícia M R Pereira

    Full Text Available Photodynamic Therapy (PDT relies on the use of non-toxic photosensitizers that are locally and selectively activated by light to induce cell death or apoptosis through reactive oxygen species generation. The conjugation of porphyrinoids with sugars that target cancer is increasingly viewed as an effective way to increase the selectivity of PDT. To date, in vitro PDT efficacy is mostly screened using two-dimensional monolayer cultures. Compared to monolayer cultures, three-dimensional spheroid cultures have unique spatial distributions of nutrients, metabolites, oxygen and signalling molecules; therefore better mimic in vivo conditions. We obtained 0.05 mm3 spheroids with four different human tumor cell lines (HCT-116, MCF-7, UM-UC-3 and HeLa with appropriate sizes for screening PDT agents. We observed that detachment from monolayer culture and growth as tumor spheroids was accompanied by changes in glucose metabolism, endogenous ROS levels, galectin-1 and glucose transporter GLUT1 protein levels. We compared the phototoxic responses of a porphyrin conjugated with four glucose molecules (PorGlu4 in monolayer and spheroid cultures. The uptake and phototoxicity of PorGlu4 is highly dependent on the monolayer versus spheroid model used and on the different levels of GLUT1 protein expressed by these in vitro platforms. This study demonstrates that HCT-116, MCF-7, UM-UC-3 and HeLa spheroids afford a more rational platform for the screening of new glycosylated-photosensitizers compared to monolayer cultures of these cancer cells.

  7. Fibroblast spheroids as a model to study sustained fibroblast quiescence and their crosstalk with tumor cells

    Energy Technology Data Exchange (ETDEWEB)

    Salmenperä, Pertteli, E-mail: pertteli.salmenpera@helsinki.fi [Department of Virology, Medicum, Faculty of Medicine, University of Helsinki, P.O. Box 21, FIN-00014 (Finland); Karhemo, Piia-Riitta [Research Programs Unit, Translational Cancer Biology, and Institute of Biomedicine, University of Helsinki, P.O. Box 63, FIN-00014 (Finland); Räsänen, Kati [Department of Virology, Medicum, Faculty of Medicine, University of Helsinki, P.O. Box 21, FIN-00014 (Finland); Laakkonen, Pirjo [Research Programs Unit, Translational Cancer Biology, and Institute of Biomedicine, University of Helsinki, P.O. Box 63, FIN-00014 (Finland); Vaheri, Antti [Department of Virology, Medicum, Faculty of Medicine, University of Helsinki, P.O. Box 21, FIN-00014 (Finland)

    2016-07-01

    Stromal fibroblasts have an important role in regulating tumor progression. Normal and quiescent fibroblasts have been shown to restrict and control cancer cell growth, while cancer-associated, i. e. activated fibroblasts have been shown to enhance proliferation and metastasis of cancer cells. In this study we describe generation of quiescent fibroblasts in multicellular spheroids and their effects on squamous cell carcinoma (SCC) growth in soft-agarose and xenograft models. Quiescent phenotype of fibroblasts was determined by global down-regulation of expression of genes related to cell cycle and increased expression of p27. Interestingly, microarray analysis showed that fibroblast quiescence was associated with similar secretory phenotype as seen in senescence and they expressed senescence-associated-β-galactosidase. Quiescent fibroblasts spheroids also restricted the growth of RT3 SCC cells both in soft-agarose and xenograft models unlike proliferating fibroblasts. Restricted tumor growth was associated with marginally increased tumor cell senescence and cellular differentiation, showed with senescence-associated-β-galactosidase and cytokeratin 7 staining. Our results show that the fibroblasts spheroids can be used as a model to study cellular quiescence and their effects on cancer cell progression. - Highlights: • Fibroblasts acquire a sustained quiescence when grown as multicellular spheroids. • This quiescence is associated with drastic change in gene expression. • Fibroblasts spheroids secrete various inflammation-linked cytokines and chemokines. • Fibroblasts spheroids reduced growth of RT3 SCC cells in xenograft model.

  8. Characterization of variants isolated from BCNU-treated 9L multicellular spheroids

    International Nuclear Information System (INIS)

    Hoff, M.H.B.; Deen, D.F.

    1984-01-01

    Multicellular spheroids of the 9L rat brain tumor cell line were treated with a single high-dose to produce cells of varying sensitivity. Treatment of 350-450 μm diameter 9L spheroids with 45 μM BCNU for 1 hr at 37 0 C produced 5 log cell kill. Some of the treated spheroids were dissociated immediately after treatment; others were dissociated after 1 wk. From these populations, twenty clones were selected and passaged as monolayers. Each clone was assayed at passage 2 for BCNU-induced damage using colony forming efficiency and sister chromatid exchange. 60% of the clones were resistant to BCNU, 15% were unchanged, and 15% appeared hypersensitive as compared with the control, which were uncloned 9L cells. All of the hypersensitive clones originated from the spheroids that remained in suspension after treatment. Three clones were studied during subsequent passage in monolayer. Two resistant clones maintained their resistance to BCNU over -- 25 passages, while one hypersensitive clone appeared to become progressively more resistant during passage. Thus, as with monolayer and in vivo 9L cells, a single high-dose treatment with BCNU produces a spectrum of sensitivities to BCNU. Some of these phenotypes are stable over many passages and have been used to initiate 9L spheroids having varying sensitivity to BCNU. These spheroids will be used to investigate drug-radiation interactions

  9. Imaging Herpes Simplex Virus Type 1 Amplicon Vector–Mediated Gene Expression in Human Glioma Spheroids

    Directory of Open Access Journals (Sweden)

    Christine Kaestle

    2011-05-01

    Full Text Available Vectors derived from herpes simplex virus type 1 (HSV-1 have great potential for transducing therapeutic genes into the central nervous system; however, inefficient distribution of vector particles in vivo may limit their therapeutic potential in patients with gliomas. This study was performed to investigate the extent of HSV-1 amplicon vector–mediated gene expression in a three-dimensional glioma model of multicellular spheroids by imaging highly infectious HSV-1 virions expressing green fluorescent protein (HSV-GFP. After infection or microscopy-guided vector injection of glioma spheroids at various spheroid sizes, injection pressures and injection times, the extent of HSV-1 vector–mediated gene expression was investigated via laser scanning microscopy. Infection of spheroids with HSV-GFP demonstrated a maximal depth of vector-mediated GFP expression at 70 to 80 μm. A > 80% transduction efficiency was reached only in small spheroids with a diameter of 90%. The results demonstrated that vector-mediated gene expression in glioma spheroids was strongly dependent on the mode of vector application—injection pressure and injection time being the most important parameters. The assessment of these vector application parameters in tissue models will contribute to the development of safe and efficient gene therapy protocols for clinical application.

  10. Transferrin targeted core-shell nanomedicine for combinatorial delivery of doxorubicin and sorafenib against hepatocellular carcinoma.

    Science.gov (United States)

    Malarvizhi, Giridharan Loghanathan; Retnakumari, Archana Payickattu; Nair, Shantikumar; Koyakutty, Manzoor

    2014-11-01

    Combinatorial drug delivery is an attractive, but challenging requirement of next generation cancer nanomedicines. Here, we report a transferrin-targeted core-shell nanomedicine formed by encapsulating two clinically used single-agent drugs, doxorubicin and sorafenib against liver cancer. Doxorubicin was loaded in poly(vinyl alcohol) nano-core and sorafenib in albumin nano-shell, both formed by a sequential freeze-thaw/coacervation method. While sorafenib from the nano-shell inhibited aberrant oncogenic signaling involved in cell proliferation, doxorubicin from the nano-core evoked DNA intercalation thereby killing >75% of cancer cells. Upon targeting using transferrin ligands, the nanoparticles showed enhanced cellular uptake and synergistic cytotoxicity in ~92% of cells, particularly in iron-deficient microenvironment. Studies using 3D spheroids of liver tumor indicated efficient penetration of targeted core-shell nanoparticles throughout the tissue causing uniform cell killing. Thus, we show that rationally designed core-shell nanoparticles can effectively combine clinically relevant single-agent drugs for exerting synergistic activity against liver cancer. Transferrin-targeted core-shell nanomedicine encapsulating doxorubicin and sorafenib was studied as a drug delivery system against hepatocellular carcinoma, resulting in enhanced and synergistic therapeutic effects, paving the way towards potential future clinical applications of similar techniques. Copyright © 2014 Elsevier Inc. All rights reserved.

  11. Shell Buckling Knockdown Factors

    Data.gov (United States)

    National Aeronautics and Space Administration — The Shell Buckling Knockdown Factor (SBKF) Project, NASA Engineering and Safety Center (NESC) Assessment #: 07-010-E, was established in March of 2007 by the NESC in...

  12. Shells and Patterns

    Science.gov (United States)

    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…

  13. Off-shell CHY amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Lam, C.S., E-mail: Lam@physics.mcgill.ca [Department of Physics, McGill University, Montreal, Q.C., H3A 2T8 (Canada); Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada); Yao, York-Peng, E-mail: yyao@umich.edu [Department of Physics, The University of Michigan Ann Arbor, MI 48109 (United States)

    2016-06-15

    The Cachazo–He–Yuan (CHY) formula for on-shell scattering amplitudes is extended off-shell. The off-shell amplitudes (amputated Green's functions) are Möbius invariant, and have the same momentum poles as the on-shell amplitudes. The working principles which drive the modifications to the scattering equations are mainly Möbius covariance and energy momentum conservation in off-shell kinematics. The same technique is also used to obtain off-shell massive scalars. A simple off-shell extension of the CHY gauge formula which is Möbius invariant is proposed, but its true nature awaits further study.

  14. Targeted radiotherapy of multicell neuroblastoma spheroids with high specific activity [125I]meta-iodobenzylguanidine

    International Nuclear Information System (INIS)

    Roa, Wilson H.Y.; Miller, Gerald G.; McEwan, Alexander J.B.; McQuarrie, Steve A.; Tse, Jeanie; Wu, Jonn; Wiebe, Leonard I.

    1998-01-01

    Purpose: Iodine-125 induces cell death by a mechanism similar to that of high linear energy transfer (high-LET) radiation. This study investigates the cytotoxicity of high-specific-activity [ 125 I]meta-iodobenzylguanidine ( 125 I-mIBG) in human SK-N-MC neuroblastoma cells grown as three-dimensional multicellular spheroids. Materials and Methods: Spheroids were incubated with high-specific-activity 125 I-mIBG (6 mCi/μg, 1000 times that of the conventional specific activity used for autoradiography). Cytotoxicity was assessed by fluorescence viability markers and confocal microscopy for intact spheroids, fluorescence-activated cell sorting and clonogenic assay, and clonogenic assays for dispersed whole spheroids. Distribution of radioactive mIBG was determined by quantitative light-microscope autoradiography of spheroid cryostat sections. Dose estimation was based on temporal knowledge of the retained radioactivity inside spheroids, and of the radiolabel's emission characteristics. Findings were compared with those of spheroids treated under the same conditions with 131 I-mIBG, cold mIBG, and free iodine-125. Results: 125 I-mIBG exerted significant cell killing. Complete spheroids were eradicated when they were treated with 500 μCi of 125 I-mIBG, while those treated with 500 μCi or 1000 μCi of 131 I-mIBG were not. The observed difference in cytotoxicity between treatments with 125 I- and 131 I-mIBG could not be accounted for by the absorbed dose of spheroid alone. The peripheral, proliferating cell layer of the spheroids remained viable at the moderate radioactivity of 100 μCi for both isotopes. Cytotoxicity induced by 125 I-mIBG was quantitatively comparable by the peripheral rim thickness to that of 131 I-mIBG at the dose of 100 μCi. The peripheral rim thickness decreased most significantly in the first 17 hours after initial treatment. There was no statistical decrease in the rim thickness identified afterwards for the second, third, and fourth days of

  15. Universal Dark Halo Scaling Relation for the Dwarf Spheroidal Satellites

    Science.gov (United States)

    Hayashi, Kohei; Ishiyama, Tomoaki; Ogiya, Go; Chiba, Masashi; Inoue, Shigeki; Mori, Masao

    2017-07-01

    Motivated by a recently found interesting property of the dark halo surface density within a radius, {r}\\max , giving the maximum circular velocity, {V}\\max , we investigate it for dark halos of the Milky Way’s and Andromeda’s dwarf satellites based on cosmological simulations. We select and analyze the simulated subhalos associated with Milky-Way-sized dark halos and find that the values of their surface densities, {{{Σ }}}{V\\max }, are in good agreement with those for the observed dwarf spheroidal satellites even without employing any fitting procedures. Moreover, all subhalos on the small scales of dwarf satellites are expected to obey the universal relation, irrespective of differences in their orbital evolutions, host halo properties, and observed redshifts. Therefore, we find that the universal scaling relation for dark halos on dwarf galaxy mass scales surely exists and provides us with important clues for understanding fundamental properties of dark halos. We also investigate orbital and dynamical evolutions of subhalos to understand the origin of this universal dark halo relation and find that most subhalos evolve generally along the {r}\\max \\propto {V}\\max sequence, even though these subhalos have undergone different histories of mass assembly and tidal stripping. This sequence, therefore, should be the key feature for understanding the nature of the universality of {{{Σ }}}{V\\max }.

  16. Three-dimensional alginate spheroid culture system of murine osteosarcoma.

    Science.gov (United States)

    Akeda, Koji; Nishimura, Akinobu; Satonaka, Haruhiko; Shintani, Ken; Kusuzaki, Katsuyuki; Matsumine, Akihiko; Kasai, Yuichi; Masuda, Koichi; Uchida, Atsumasa

    2009-11-01

    Osteosarcoma (OS) is the most common primary malignant tumor of the bone and often forms pulmonary metastases, which are the most important prognostic factor. For further elucidation of the mechanism underlying the progression and metastasis of human OS, a culture system mimicking the microenvironment of the tumor in vivo is needed. We report a novel three-dimensional (3D) alginate spheroid culture system of murine osteosarcoma. Two different metastatic clones, the parental Dunn and its derivative line LM8, which has a higher metastatic potential to the lungs, were encapsulated in alginate beads to develop the 3D culture system. The beads containing murine OS cells were also transplanted into mice to determine their metastatic potential in vivo. In this culture system, murine OS cells encapsulated in alginate beads were able to grow in a 3D structure with cells detaching from the alginate environment. The number of detaching cells was higher in the LM8 cell line than the Dunn cell line. In the in vivo alginate bead transplantation model, the rate of pulmonary metastasis was higher with LM8 cells compared with that of Dunn cells. The cell characteristics and kinetics in this culture system closely reflect the original malignant potential of the cells in vivo.

  17. ON THE r -PROCESS ENRICHMENT OF DWARF SPHEROIDAL GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Bramante, Joseph [Department of Physics, 225 Nieuwland Science Hall, University of Notre Dame, Notre Dame, IN 46556 (United States); Linden, Tim [Center for Cosmology and AstroParticle Physics (CCAPP) and Department of Physics The Ohio State University, Columbus OH, 43210 (United States)

    2016-07-20

    Recent observations of Reticulum II have uncovered an overabundance of r -process elements compared to similar ultra-faint dwarf spheroidal galaxies (UFDs). Because the metallicity and star formation history of Reticulum II appear consistent with all known UFDs, the high r -process abundance of Reticulum II suggests enrichment through a single, rare event, such as a double neutron star (NS) merger. However, we note that this scenario is extremely unlikely, as binary stellar evolution models require significant supernova natal kicks to produce NS–NS or NS–black hole (BH) mergers, and these kicks would efficiently remove compact binary systems from the weak gravitational potentials of UFDs. We examine alternative mechanisms for the production of r -process elements in UFDs, including a novel mechanism wherein NSs in regions of high dark matter (DM) density implode after accumulating a BH-forming mass of DM. We find that r -process proto-material ejection by tidal forces, when a single NS implodes into a BH, can occur at a rate matching the r -process abundance of both Reticulum II and the Milky Way. Remarkably, DM models which collapse a single NS in observed UFDs also solve the missing pulsar problem in the Milky Way Galactic Center. We propose tests specific to DM r -process production which may uncover or rule out this model.

  18. The Variable Stars of the Draco Dwarf Spheroidal Galaxy: Revisited

    Science.gov (United States)

    Kinemuchi, K.; Harris, H. C.; Smith, Horace A.; Silbermann, N. A.; Snyder, L. A.; La Cluyzé, A. P.; Clark, C. L.

    2008-11-01

    We present a CCD survey of variable stars in the Draco dwarf spheroidal galaxy. This survey, which has the largest areal coverage since the original variable star survey by Baade & Swope, includes photometry for 270 RR Lyrae (RRL) stars, 9 anomalous Cepheids (ACs), 2 eclipsing binaries, and 12 slow, irregular red variables, as well as 30 background QSOs. Twenty-six probable double-mode RRL stars were identified. Observed parameters, including mean V and I magnitudes, V amplitudes, and periods, have been derived. Photometric metallicities of the ab-type RRL stars were calculated according to the method of Jurcsik & Kovacs, yielding a mean metallicity of lang[Fe/H]rang = -2.19 ± 0.03. The well-known Oosterhoff intermediate nature of the RRL stars in Draco is reconfirmed, although the double-mode RRL stars, with one exception, have properties similar to those found in Oosterhoff type II globular clusters. The period-luminosity relation of the ACs is rediscussed with the addition of the new Draco ACs.

  19. A Kinematic Study of the Andromeda Dwarf Spheroidal System

    Science.gov (United States)

    Collins, Michelle L. M.; Chapman, Scott C.; Rich, R. Michael; Ibata, Rodrigo A.; Martin, Nicolas F.; Irwin, Michael J.; Bate, Nicholas F.; Lewis, Geraint F.; Peñarrubia, Jorge; Arimoto, Nobuo; Casey, Caitlin M.; Ferguson, Annette M. N.; Koch, Andreas; McConnachie, Alan W.; Tanvir, Nial

    2013-05-01

    We present a homogeneous kinematic analysis of red giant branch stars within 18 of the 28 Andromeda dwarf spheroidal (dSph) galaxies, obtained using the Keck I/LRIS and Keck II/DEIMOS spectrographs. Based on their g - i colors (taken with the CFHT/MegaCam imager), physical positions on the sky, and radial velocities, we assign probabilities of dSph membership to each observed star. Using this information, the velocity dispersions, central masses, and central densities of the dark matter halos are calculated for these objects, and compared with the properties of the Milky Way dSph population. We also measure the average metallicity ([Fe/H]) from the co-added spectra of member stars for each M31 dSph and find that they are consistent with the trend of decreasing [Fe/H] with luminosity observed in the Milky Way population. We find that three of our studied M31 dSphs appear as significant outliers in terms of their central velocity dispersion, And XIX, XXI, and XXV, all of which have large half-light radii (gsim 700 pc) and low velocity dispersions (σ v ratio within its half-light radius of just [M/L]_half=10.3^{+7.0}_{-6.7}, making it consistent with a simple stellar system with no appreciable dark matter component within its 1σ uncertainties. We suggest that the structure of the dark matter halos of these outliers have been significantly altered by tides.

  20. A Chemical Evolution Model for the Fornax Dwarf Spheroidal Galaxy

    Directory of Open Access Journals (Sweden)

    Yuan Zhen

    2016-01-01

    Full Text Available Fornax is the brightest Milky Way (MW dwarf spheroidal galaxy and its star formation history (SFH has been derived from observations. We estimate the time evolution of its gas mass and net inflow and outflow rates from the SFH usinga simple star formation law that relates the star formation rate to the gas mass. We present a chemical evolution model on a 2D mass grid with supernovae (SNe as sources of metal enrichment. We find that a key parameter controlling the enrichment is the mass Mx of the gas to mix with the ejecta from each SN. The choice of Mx depends on the evolution of SN remnants and on the global gas dynamics. It differs between the two types of SNe involved and between the periods before and after Fornax became an MW satellite at time t = tsat. Our results indicate that due to the global gas outflow at t > tsat, part of the ejecta from each SN may directly escape from Fornax. Sample results from our model are presented and compared with data.

  1. Experimental evidence for several spheroid growth mechanisms in the liquid-phase sintered tungsten-base composites

    International Nuclear Information System (INIS)

    Zukas, E.G.; Rogers, P.S.Z.; Rogers, R.S.

    1976-01-01

    The generally accepted mechanism for spheroid growth during sintering of tungsten-base composites in the presence of a liquid phase is the dissolution of the small spheroids with simultaneous precipitation of tungsten from the molten matrix onto the larger spheroids, the process being driven by the difference in surface energy between the larger and smaller spheroids. From theoretical considerations, the slope of the straight line of log diameter versus log time should be 1 / 3 for this process. The experimental evidence for the dissolution and reprecipitation mechanism is meager, being based primarily on the spheroid growth rate during the latter stages of liquid-phase sintering. Experimental evidence is presented that shows spheroid growth taking place in systems where the tungsten and the matrix are mutually insoluble thereby making dissolution and reprecipitation impossible. Furthermore, the results from these studies and others using the usual matrix compositions indicate that spheroid growth takes place predominantly by the combination or coalescence of two or more spheroids. Deposition of tungsten from the molten matrix also occurs, although not necessarily on spheroid surfaces which have the lowest surface energy. Thus, many mechanisms, each depending on temperature and other variables, operate simultaneously. A satisfactory theoretical treatment must include them all

  2. Retrieval of spheroid particle size distribution from spectral extinction data in the independent mode using PCA approach

    International Nuclear Information System (INIS)

    Tang, Hong; Lin, Jian-Zhong

    2013-01-01

    An improved anomalous diffraction approximation (ADA) method is presented for calculating the extinction efficiency of spheroids firstly. In this approach, the extinction efficiency of spheroid particles can be calculated with good accuracy and high efficiency in a wider size range by combining the Latimer method and the ADA theory, and this method can present a more general expression for calculating the extinction efficiency of spheroid particles with various complex refractive indices and aspect ratios. Meanwhile, the visible spectral extinction with varied spheroid particle size distributions and complex refractive indices is surveyed. Furthermore, a selection principle about the spectral extinction data is developed based on PCA (principle component analysis) of first derivative spectral extinction. By calculating the contribution rate of first derivative spectral extinction, the spectral extinction with more significant features can be selected as the input data, and those with less features is removed from the inversion data. In addition, we propose an improved Tikhonov iteration method to retrieve the spheroid particle size distributions in the independent mode. Simulation experiments indicate that the spheroid particle size distributions obtained with the proposed method coincide fairly well with the given distributions, and this inversion method provides a simple, reliable and efficient method to retrieve the spheroid particle size distributions from the spectral extinction data. -- Highlights: ► Improved ADA is presented for calculating the extinction efficiency of spheroids. ► Selection principle about spectral extinction data is developed based on PCA. ► Improved Tikhonov iteration method is proposed to retrieve the spheroid PSD.

  3. Radiosensitivity of different human tumor cells lines grown as multicellular spheroids determined from growth curves and survival data

    International Nuclear Information System (INIS)

    Schwachoefer, J.H.C.; Crooijmans, R.P.; van Gasteren, J.J.; Hoogenhout, J.; Jerusalem, C.R.; Kal, H.B.; Theeuwes, A.G.

    1989-01-01

    Five human tumor cell lines were grown as multicellular tumor spheroids (MTS) to determine whether multicellular tumor spheroids derived from different types of tumors would show tumor-type dependent differences in response to single-dose irradiation, and whether these differences paralleled clinical behavior. Multicellular tumor spheroids of two neuroblastoma, one lung adenocarcinoma, one melanoma, and a squamous cell carcinoma of the oral tongue, were studied in terms of growth delay, calculated cell survival, and spheroid control dose50 (SCD50). Growth delay and cell survival analysis for the tumor cell lines showed sensitivities that correlated well with clinical behavior of the tumor types of origin. Similar to other studies on melanoma multicellular tumor spheroids our spheroid control dose50 results for the melanoma cell line deviated from the general pattern of sensitivity. This might be due to the location of surviving cells, which prohibits proliferation of surviving cells and hence growth of melanoma multicellular tumor spheroids. This study demonstrates that radiosensitivity of human tumor cell lines can be evaluated in terms of growth delay, calculated cell survival, and spheroid control dose50 when grown as multicellular tumor spheroids. The sensitivity established from these evaluations parallels clinical behavior, thus offering a unique tool for the in vitro analysis of human tumor radiosensitivity

  4. Generation of Multicellular Tumor Spheroids with Microwell-Based Agarose Scaffolds for Drug Testing.

    Directory of Open Access Journals (Sweden)

    Xue Gong

    Full Text Available Three dimensional multicellular aggregate, also referred to as cell spheroid or microtissue, is an indispensable tool for in vitro evaluating antitumor activity and drug efficacy. Compared with classical cellular monolayer, multicellular tumor spheroid (MCTS offers a more rational platform to predict in vivo drug efficacy and toxicity. Nevertheless, traditional processing methods such as plastic dish culture with nonadhesive surfaces are regularly time-consuming, laborious and difficult to provide uniform-sized spheroids, thus causing poor reproducibility of experimental data and impeding high-throughput drug screening. In order to provide a robust and effective platform for in vitro drug evaluation, we present an agarose scaffold prepared with the template containing uniform-sized micro-wells in commercially available cell culture plates. The agarose scaffold allows for good adjustment of MCTS size and large-scale production of MCTS. Transparent agarose scaffold also allows for monitoring of spheroid formation under an optical microscopy. The formation of MCTS from MCF-7 cells was prepared using different-size-well templates and systematically investigated in terms of spheroid growth curve, circularity, and cell viability. The doxorubicin cytotoxicity against MCF-7 spheroid and MCF-7 monolayer cells was compared. The drug penetration behavior, cell cycle distribution, cell apoptosis, and gene expression were also evaluated in MCF-7 spheroid. The findings of this study indicate that, compared with cellular monolayer, MCTS provides a valuable platform for the assessment of therapeutic candidates in an in vivo-mimic microenvironment, and thus has great potential for use in drug discovery and tumor biology research.

  5. Dyson shells: a retrospective

    Science.gov (United States)

    Bradbury, Robert J.

    2001-08-01

    More than 40 years have passed since Freeman Dyson suggested that advanced technological civilizations are likely to dismantle planets in their solar systems to harvest all of the energy their stars wastefully radiate into space. Clearly this was an idea that was ahead of its time. Since that time, dozens of SETI searches have been conducted and almost all of them have focused their attention on stars which by definition cannot be the advanced civilizations that Dyson envisioned. I will review the data that created the confusion between Dyson spheres and Dyson shells. The sources that disprove Dyson spheres while still allowing Dyson shells will be discussed. The use of outmoded ideas that have biased the few searches for Dyson Shells that have occurred will be pointed out. An update of the concept of Dyson shells to include our current knowledge of biotechnology, nanotechnology and computer science will be explored. Finally, an approach to setting limits on the abundance of Dyson shells in our galaxy using existing optical astronomical data and future optical satellites will be proposed.

  6. Structure and Formation of Elliptical and Spheroidal Galaxies

    Science.gov (United States)

    Kormendy, John; Fisher, David B.; Cornell, Mark E.; Bender, Ralf

    2009-05-01

    dichotomy between elliptical and spheroidal galaxies. Their properties are consistent with our understanding of their different formation processes: mergers for ellipticals and conversion of late-type galaxies into spheroidals by environmental effects and by energy feedback from supernovae. In an appendix, we develop machinery to get realistic error estimates for Sérsic parameters even when they are strongly coupled. And we discuss photometric dynamic ranges necessary to get robust results from Sérsic fits. Based in part on observations obtained with the Hobby-Eberly Telescope (HET), which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universität München, and Georg-August-Universität Göttingen.

  7. Porous Nb-Ti based alloy produced from plasma spheroidized powder

    Directory of Open Access Journals (Sweden)

    Qijun Li

    Full Text Available Spherical Nb-Ti based alloy powder was prepared by the combination of plasma spheroidization and mechanical alloying. Phase constituents, microstructure and surface state of the powder, and pore characteristics of the resulting porous alloy were investigated. The results show that the undissolved W and V in the mechanically alloyed powder is fully alloyed after spheroidization, and single β phase is achieved. Particle size of the spheroidized powder is in the range of 20–110 μm. With the decrease of particle size, a transformation from typical dendrite solidification structure to fine cell microstructure occurs. The surface of the spheroidized powder is coated by a layer of oxides consisting mainly of TiO2 and Nb2O5. Probabilities of sinter-neck formation and particle coalescence increases with increasing sintering temperature. Porous skeleton with relatively homogeneous pore distribution and open pore channel is formed after vacuum sintering at 1700 °C, and the porosity is 32%. The sintering kinetic analysis indicates that grain boundary diffusion is the primary mass transport mechanism during sintering process. Keywords: Powder metallurgy, Nb-Ti based alloy, Porous material, Mechanical alloying, Plasma spheroidizing, Solidification microstructure

  8. Elemental mapping by synchrotron radiation X-Ray microfluorescence in cellular spheroid of prostate tumor cells

    Energy Technology Data Exchange (ETDEWEB)

    Leitao, R.G.; Anjos, M.J.; Lopes, R.T., E-mail: roberta@lin.ufrj.br [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Lab. de Instrumentacao Nuclear; Santos, C.A.N. [Instituto Nacional de Metrologia, Qualidade e Tecnologia (INMETRO), Duque de Caxias, RJ (Brazil). Lab. de Biotecnologia; Palumbo Junior, A.; Souza, P.A.V.R.; Nasciutti, L.E. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Instituto de Ciencias Biomedicas; Pereira, G.R. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Lab. de Ensaios Nao Destrutivos, Corrosao e Soldagem

    2013-08-15

    Prostate cancer is the sixth most common type of cancer and the third most common in males in Western industrialized countries. Cellular spheroid serves as excellent physiologic tumor models as they mimic avascular tumors and micrometastases. Trace elements play a significant role in biological processes. They are capable of affecting human health by competing with essential elements for available binding sites and by the activation or inhibition of reactions between metabolic enzymes. It is well known that zinc levels in the peripheral zone of dorsal and lateral lobes of the prostate are almost 10 times higher than in other soft tissues. Prostate tumor cells were isolated of the prostate tissue samples that were collected from patients submitted to surgery. The measurements were performed in XRF beam line at the Synchrotron Light National Laboratory (LNLS) in Campinas, Brazil. The results showed that all elements were heterogeneously distributed in different areas of the spheroids analyzed. P, S and Cl showed similar elemental distribution in all the samples analyzed while K, Ca, Fe, and Cu showed different elemental distribution. In all spheroids analyzed, Zn presented more intense distributions in the central region of the spheroid. The relationship between the function of Zn in the secretory epithelial cells and the carcinogenic process suggests that more studies on elemental mapping in spheroids are necessary. (author)

  9. Cell invasion in the spheroid sprouting assay: a spatial organisation analysis adaptable to cell behaviour.

    Directory of Open Access Journals (Sweden)

    Silvia Blacher

    Full Text Available The endothelial cell spheroid assay provides a suitable in vitro model to study (lymph angiogenesis and test pro- and anti-(lymph angiogenic factors or drugs. Usually, the extent of cell invasion, observed through optical microscopy, is measured. The present study proposes the spatial distribution of migrated cells as a new descriptor of the (lymph angiogenic response. The utility of this novel method rests with its capacity to locally characterise spheroid structure, allowing not only the investigation of single and collective cell invasion but also the evolution of the spheroid core itself. Moreover, the proposed method can be applied to 2D-projected spheroid images obtained by optical microscopy, as well as to 3D images acquired by confocal microscopy. To validate the proposed methodology, endothelial cell invasion was evaluated under different experimental conditions. The results were compared with widely used global parameters. The comparison shows that our method prevents local spheroid modifications from being overlooked and leading to the possible misinterpretation of results.

  10. Elemental mapping by synchrotron radiation X-Ray microfluorescence in cellular spheroid of prostate tumor cells

    International Nuclear Information System (INIS)

    Leitao, R.G.; Anjos, M.J.; Lopes, R.T.; Santos, C.A.N.; Palumbo Junior, A.; Souza, P.A.V.R.; Nasciutti, L.E.; Pereira, G.R.

    2013-01-01

    Prostate cancer is the sixth most common type of cancer and the third most common in males in Western industrialized countries. Cellular spheroid serves as excellent physiologic tumor models as they mimic avascular tumors and micrometastases. Trace elements play a significant role in biological processes. They are capable of affecting human health by competing with essential elements for available binding sites and by the activation or inhibition of reactions between metabolic enzymes. It is well known that zinc levels in the peripheral zone of dorsal and lateral lobes of the prostate are almost 10 times higher than in other soft tissues. Prostate tumor cells were isolated of the prostate tissue samples that were collected from patients submitted to surgery. The measurements were performed in XRF beam line at the Synchrotron Light National Laboratory (LNLS) in Campinas, Brazil. The results showed that all elements were heterogeneously distributed in different areas of the spheroids analyzed. P, S and Cl showed similar elemental distribution in all the samples analyzed while K, Ca, Fe, and Cu showed different elemental distribution. In all spheroids analyzed, Zn presented more intense distributions in the central region of the spheroid. The relationship between the function of Zn in the secretory epithelial cells and the carcinogenic process suggests that more studies on elemental mapping in spheroids are necessary. (author)

  11. Influence of reaction chamber shape on cast-iron spheroidization process in-mold

    Directory of Open Access Journals (Sweden)

    S. Pietrowski

    2010-01-01

    Full Text Available This paper presents a results concerning the influence of reaction chamber shape on cast – iron spheroidization process in form. The volume of the tested reaction chambers was about 118000mm3. Reaction chambers in the shape of: rectangular, cylinder and spherical cap were examined. It has been shown that the best graphite spheroidizing process was provided by spherical cap chamber shape. The reaction of cast – iron with magnesium in reaction chamber depends on the flow of cast – iron in the chamber. In rectangular and cylinder shape chambers proceed the impact of diphase stream on flat bottom wall. It causes the creation on its surface film, called: cast – iron “film”, where single grains of magnesium master alloy exist. The largest part of master alloy is drifted by liquid cast – iron to the top and only there graphite spheroidization process proceed. In the spherical cap shape reaction chamber, as a result of rotation movement of liquid cast – iron throughout its volume, graphite spheroidization process proceed. Apart from the reaction chamber shape, applying of mixing chamber ensure full cast – iron spheroidization process.

  12. Application of Mie theory to assess structure of spheroidal scattering in backscattering geometries.

    Science.gov (United States)

    Chalut, Kevin J; Giacomelli, Michael G; Wax, Adam

    2008-08-01

    Inverse light scattering analysis seeks to associate measured scattering properties with the most probable theoretical scattering distribution. Although Mie theory is a spherical scattering model, it has been used successfully for discerning the geometry of spheroidal scatterers. The goal of this study was an in-depth evaluation of the consequences of analyzing the structure of spheroidal geometries, which are relevant to cell and tissue studies in biology, by employing Mie-theory-based inverse light scattering analysis. As a basis for this study, the scattering from spheroidal geometries was modeled using T-matrix theory and used as test data. In a previous study, we used this technique to investigate the case of spheroidal scatterers aligned with the optical axis. In the present study, we look at a broader scope which includes the effects of aspect ratio, orientation, refractive index, and incident light polarization. Over this wide range of parameters, our results indicate that this method provides a good estimate of spheroidal structure.

  13. Engineered Breast Cancer Cell Spheroids Reproduce Biologic Properties of Solid Tumors.

    Science.gov (United States)

    Ham, Stephanie L; Joshi, Ramila; Luker, Gary D; Tavana, Hossein

    2016-11-01

    Solid tumors develop as 3D tissue constructs. As tumors grow larger, spatial gradients of nutrients and oxygen and inadequate diffusive supply to cells distant from vasculature develops. Hypoxia initiates signaling and transcriptional alterations to promote survival of cancer cells and generation of cancer stem cells (CSCs) that have self-renewal and tumor-initiation capabilities. Both hypoxia and CSCs are associated with resistance to therapies and tumor relapse. This study demonstrates that 3D cancer cell models, known as tumor spheroids, generated with a polymeric aqueous two-phase system (ATPS) technology capture these important biological processes. Similar to solid tumors, spheroids of triple negative breast cancer cells deposit major extracellular matrix proteins. The molecular analysis establishes presence of hypoxic cells in the core region and expression of CSC gene and protein markers including CD24, CD133, and Nanog. Importantly, these spheroids resist treatment with chemotherapy drugs. A combination treatment approach using a hypoxia-activated prodrug, TH-302, and a chemotherapy drug, doxorubicin, successfully targets drug resistant spheroids. This study demonstrates that ATPS spheroids recapitulate important biological and functional properties of solid tumors and provide a unique model for studies in cancer research. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Spheroidal Carbonaceous Particles (SCPs) as Chronological Markers in Marine Sediments

    Science.gov (United States)

    Thornalley, D.; Rose, N.; Oppo, D.

    2016-12-01

    Spheroidal carbonaceous particles (SCPs) are a component of fly-ash, the particulate by-product of industrial high-temperature combustion of coal and fuel-oil that is released to the atmosphere with flue-gases. They are morphologically distinct and have no natural sources making them unambiguous markers of contamination from these anthropogenic sources. In naturally accumulating archives, SCPs may be used as a chronological tool as they provide a faithful record of industrial emissions and deposition. While the timing of the first presence of SCP in the 19th century, and the observed sub-surface peak are dependent on factors such as sediment accumulation rates and local industrial history, a rapid increase in SCP inputs in the mid-20thcentury appears to be a global signal corresponding to an acceleration in global electricity demand following the Second World War and the use of fuel-oil in electricity production at an industrial scale for the first time. While this approach has been widely used in lake sediments, it has not been applied to marine sediments, although there is great potential. Improved dating of 19th-20th century marine sediments has particular relevance for developing reconstructions of recent multi-decadal climate and ocean variability, and for studies that aim to place 20thcentury climate change within the context of the last millennium. Here, we present data from three sediment cores from the continental slope south of Iceland to demonstrate the temporal and spatial replicability of the SCP record in the marine environment and compare these data with cores taken from more contaminated areas off the coast of the eastern United States. The improved age model constraints provided by the analysis of SCPs has enabled a more accurate assessment of the timing of recent abrupt climate events recorded in these archives and has thus improved our understanding of likely causal climate mechanisms.

  15. A KINEMATIC STUDY OF THE ANDROMEDA DWARF SPHEROIDAL SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    Collins, Michelle L. M.; Martin, Nicolas F. [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany); Chapman, Scott C.; Irwin, Michael J. [Institute of Astronomy, Madingley Rise, Cambridge CB3 0HA (United Kingdom); Rich, R. Michael [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1547 (United States); Ibata, Rodrigo A. [Observatoire astronomique de Strasbourg, Universite de Strasbourg, CNRS, UMR 7550, 11 rue de l' Universite, F-67000 Strasbourg (France); Bate, Nicholas F.; Lewis, Geraint F. [Sydney Institute for Astronomy, School of Physics, A28, University of Sydney, NSW 2006 (Australia); Penarrubia, Jorge [Instituto de Astrofisica de Andalucia-CSIC, Glorieta de la Astronomia s/n, E-18008 Granada (Spain); Arimoto, Nobuo [Subaru Telescope, National Astronomical Observatory of Japan, 650 North A' ohoku Place, Hilo, HI 96720 (United States); Casey, Caitlin M. [Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, HI 96822-1839 (United States); Ferguson, Annette M. N. [Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Koch, Andreas [Zentrum fuer Astronomie der Universitaet Heidelberg, Landessternwarte, Koenigstuhl 12, D-69117 Heidelberg (Germany); McConnachie, Alan W. [NRC Herzberg Institute of Astrophysics, 5071 West Saanich Road, British Columbia, Victoria V9E 2E7 (Canada); Tanvir, Nial [Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom)

    2013-05-10

    We present a homogeneous kinematic analysis of red giant branch stars within 18 of the 28 Andromeda dwarf spheroidal (dSph) galaxies, obtained using the Keck I/LRIS and Keck II/DEIMOS spectrographs. Based on their g - i colors (taken with the CFHT/MegaCam imager), physical positions on the sky, and radial velocities, we assign probabilities of dSph membership to each observed star. Using this information, the velocity dispersions, central masses, and central densities of the dark matter halos are calculated for these objects, and compared with the properties of the Milky Way dSph population. We also measure the average metallicity ([Fe/H]) from the co-added spectra of member stars for each M31 dSph and find that they are consistent with the trend of decreasing [Fe/H] with luminosity observed in the Milky Way population. We find that three of our studied M31 dSphs appear as significant outliers in terms of their central velocity dispersion, And XIX, XXI, and XXV, all of which have large half-light radii ({approx}> 700 pc) and low velocity dispersions ({sigma}{sub v} < 5 km s{sup -1}). In addition, And XXV has a mass-to-light ratio within its half-light radius of just [M/L]{sub half}=10.3{sup +7.0}{sub -6.7}, making it consistent with a simple stellar system with no appreciable dark matter component within its 1{sigma} uncertainties. We suggest that the structure of the dark matter halos of these outliers have been significantly altered by tides.

  16. A KINEMATIC STUDY OF THE ANDROMEDA DWARF SPHEROIDAL SYSTEM

    International Nuclear Information System (INIS)

    Collins, Michelle L. M.; Martin, Nicolas F.; Chapman, Scott C.; Irwin, Michael J.; Rich, R. Michael; Ibata, Rodrigo A.; Bate, Nicholas F.; Lewis, Geraint F.; Peñarrubia, Jorge; Arimoto, Nobuo; Casey, Caitlin M.; Ferguson, Annette M. N.; Koch, Andreas; McConnachie, Alan W.; Tanvir, Nial

    2013-01-01

    We present a homogeneous kinematic analysis of red giant branch stars within 18 of the 28 Andromeda dwarf spheroidal (dSph) galaxies, obtained using the Keck I/LRIS and Keck II/DEIMOS spectrographs. Based on their g – i colors (taken with the CFHT/MegaCam imager), physical positions on the sky, and radial velocities, we assign probabilities of dSph membership to each observed star. Using this information, the velocity dispersions, central masses, and central densities of the dark matter halos are calculated for these objects, and compared with the properties of the Milky Way dSph population. We also measure the average metallicity ([Fe/H]) from the co-added spectra of member stars for each M31 dSph and find that they are consistent with the trend of decreasing [Fe/H] with luminosity observed in the Milky Way population. We find that three of our studied M31 dSphs appear as significant outliers in terms of their central velocity dispersion, And XIX, XXI, and XXV, all of which have large half-light radii (∼> 700 pc) and low velocity dispersions (σ v –1 ). In addition, And XXV has a mass-to-light ratio within its half-light radius of just [M/L] half =10.3 +7.0 -6.7 , making it consistent with a simple stellar system with no appreciable dark matter component within its 1σ uncertainties. We suggest that the structure of the dark matter halos of these outliers have been significantly altered by tides.

  17. Scission-point model of nuclear fission based on deformed-shell effects

    International Nuclear Information System (INIS)

    Wilkins, B.D.; Steinberg, E.P.; Chasman, R.R.

    1976-01-01

    A static model of nuclear fission is proposed based on the assumption of statistical equilibrium among collective degrees of freedom at the scission point. The relative probabilities of formation of complementary fission fragment pairs are determined from the relative potential energies of a system of two nearly touching, coaxial spheroids with quadrupole deformations. The total potential energy of the system at the scission point is calculated as the sum of liquid-drop and shell- and pairing-correction terms for each spheroid, and Coulomb and nuclear potential terms describing the interaction between them. The fissioning system at the scission point is characterized by three parameters: the distance between the tips of the spheroids (d), the intrinsic excitation energy of the fragments (tau/sub int/), and a collective temperature (T/sub coll/). No attempt is made to adjust these parameters to give optimum fits to experimental data, but rather, a single choice of values for d, tau/sub int/, and T/sub coll/ is used in the calculations for all fissioning systems. The general trends of the distributions of mass, nuclear charge, and kinetic energy in the fission of a wide range of nuclides from Po to Fm are well reproduced in the calculations. The major influence of the deformed-shell corrections for neutrons is indicated and provides a convenient framework for the interpretation of observed trends in the data and for the prediction of new results. The scission-point configurations derived from the model provide an interpretation of the ''saw-tooth'' neutron emission curve as well as previously unexplained observations on the variation of TKE for isotopes of U, Pu, Cm, and Cf; structure in the width of total kinetic energy release as a function of fragment mass ratio; and a difference in threshold energies for symmetric and asymmetric mass splits in the fission of Ra and Ac isotopes

  18. NIF Double Shell outer/inner shell collision experiments

    Science.gov (United States)

    Merritt, E. C.; Loomis, E. N.; Wilson, D. C.; Cardenas, T.; Montgomery, D. S.; Daughton, W. S.; Dodd, E. S.; Desjardins, T.; Renner, D. B.; Palaniyappan, S.; Batha, S. H.; Khan, S. F.; Smalyuk, V.; Ping, Y.; Amendt, P.; Schoff, M.; Hoppe, M.

    2017-10-01

    Double shell capsules are a potential low convergence path to substantial alpha-heating and ignition on NIF, since they are predicted to ignite and burn at relatively low temperatures via volume ignition. Current LANL NIF double shell designs consist of a low-Z ablator, low-density foam cushion, and high-Z inner shell with liquid DT fill. Central to the Double Shell concept is kinetic energy transfer from the outer to inner shell via collision. The collision determines maximum energy available for compression and implosion shape of the fuel. We present results of a NIF shape-transfer study: two experiments comparing shape and trajectory of the outer and inner shells at post-collision times. An outer-shell-only target shot measured the no-impact shell conditions, while an `imaging' double shell shot measured shell conditions with impact. The `imaging' target uses a low-Z inner shell and is designed to perform in similar collision physics space to a high-Z double shell but can be radiographed at 16keV, near the viable 2DConA BL energy limit. Work conducted under the auspices of the U.S. DOE by LANL under contract DE-AC52-06NA25396.

  19. Radiation cell survival and growth delay studies in multicellular spheroids of small-cell lung carcinoma

    International Nuclear Information System (INIS)

    Duchesne, G.M.; Peacock, J.H.

    1987-01-01

    The radiation sensitivity of two small-cell lung carcinoma cell lines growing as multicellular spheroids in static culture was determined using clonogenic cell survival and growth delay as endpoints. Growth delay determination suggested that clonogenic cell kill was less than was obtained by direct assay of cell survival. Recovery from potentially lethal damage was assayed in one line (HC12) but was not demonstrable, and clonogenic cell survival decreased with time in treated spheroids with diameters greater than 300 μm which contained a hypoxic cell population. Microscopic examination of the treated spheroids showed the emergence of an abnormal giant-cell population, and the progressive clonogenic cell loss that occurred after treatment was thought to be due to oxygen and nutrient deprivation of the remaining viable cells by this doomed cell population. Correction of the growth delay measurements for changes in cell size and clonogenic cell population allowed correlation of the growth delay and cell survival data. (author)

  20. Heterogenic expression of stem cell markers in patient-derived glioblastoma spheroid cultures exposed to long-term hypoxia

    DEFF Research Database (Denmark)

    Rosenberg, Tine; Aaberg-Jessen, Charlotte; Petterson, Stine Asferg

    2018-01-01

    AIM: To investigate the time profile of hypoxia and stem cell markers in glioblastoma spheroids of known molecular subtype. MATERIALS & METHODS: Patient-derived glioblastoma spheroids were cultured up to 7 days in either 2% or 21% oxygen. Levels of proliferation (Ki-67), hypoxia (HIF-1α, CA9...

  1. Scaffold-Free Coculture Spheroids of Human Colonic Adenocarcinoma Cells and Normal Colonic Fibroblasts Promote Tumorigenicity in Nude Mice

    Directory of Open Access Journals (Sweden)

    Jong-il Park

    2016-02-01

    Full Text Available The aim of this study was to form a scaffold-free coculture spheroid model of colonic adenocarcinoma cells (CACs and normal colonic fibroblasts (NCFs and to use the spheroids to investigate the role of NCFs in the tumorigenicity of CACs in nude mice. We analysed three-dimensional (3D scaffold-free coculture spheroids of CACs and NCFs. CAC Matrigel invasion assays and tumorigenicity assays in nude mice were performed to examine the effect of NCFs on CAC invasive behaviour and tumorigenicity in 3D spheroids. We investigated the expression pattern of fibroblast activation protein-α (FAP-α by immunohistochemical staining. CAC monocultures did not form densely-packed 3D spheroids, whereas cocultured CACs and NCFs formed 3D spheroids. The 3D coculture spheroids seeded on a Matrigel extracellular matrix showed higher CAC invasiveness compared to CACs alone or CACs and NCFs in suspension. 3D spheroids injected into nude mice generated more and faster-growing tumors compared to CACs alone or mixed suspensions consisting of CACs and NCFs. FAP-α was expressed in NCFs-CACs cocultures and xenograft tumors, whereas monocultures of NCFs or CACs were negative for FAP-α expression. Our findings provide evidence that the interaction between CACs and NCFs is essential for the tumorigenicity of cancer cells as well as for tumor propagation.

  2. Modeling mechanical inhomogeneities in small populations of proliferating monolayers and spheroids.

    Science.gov (United States)

    Lejeune, Emma; Linder, Christian

    2018-06-01

    Understanding the mechanical behavior of multicellular monolayers and spheroids is fundamental to tissue culture, organism development, and the early stages of tumor growth. Proliferating cells in monolayers and spheroids experience mechanical forces as they grow and divide and local inhomogeneities in the mechanical microenvironment can cause individual cells within the multicellular system to grow and divide at different rates. This differential growth, combined with cell division and reorganization, leads to residual stress. Multiple different modeling approaches have been taken to understand and predict the residual stresses that arise in growing multicellular systems, particularly tumor spheroids. Here, we show that by using a mechanically robust agent-based model constructed with the peridynamic framework, we gain a better understanding of residual stresses in multicellular systems as they grow from a single cell. In particular, we focus on small populations of cells (1-100 s) where population behavior is highly stochastic and prior investigation has been limited. We compare the average strain energy density of cells in monolayers and spheroids using different growth and division rules and find that, on average, cells in spheroids have a higher strain energy density than cells in monolayers. We also find that cells in the interior of a growing spheroid are, on average, in compression. Finally, we demonstrate the importance of accounting for stochastic fluctuations in the mechanical environment, particularly when the cellular response to mechanical cues is nonlinear. The results presented here serve as a starting point for both further investigation with agent-based models, and for the incorporation of major findings from agent-based models into continuum scale models when explicit representation of individual cells is not computationally feasible.

  3. Radiation survival of cells from spheroids grown in different oxygen concentrations

    International Nuclear Information System (INIS)

    Franko, A.J.; Sutherland, R.M.

    1979-01-01

    The position of the internal, chronically hypoxic cells in spheroids was varied by alterations in the oxygen concentration in the growth medium. Such alterations were expected to cause large changes in the size of the radiobiologically hypoxic fraction. This was tested by growing and irradiating spheroids in oxygen concentrations between 5 and 20.3%, ensuring that the irradiation and growth conditions were as similar as possible. The survival curves appeared to be linear below a surviving fraction of 3 x 10 -2 , and the slopes were intermediate between the slopes of control curves for cells from spheroids irradiated in nitrogen or when fully oxygenated. Thus direct estimates of the hypoxic fractions could not be made. Two models of oxygen diffusion might explain the data. One model assumes that a large fraction of cells was fully hypoxic (radiobiologically) and that these internal, G 1 -confined, chronically hypoxic cells had a lower inherent radioresistance than the outer proliferating cells. Evidence was presented which indicated that this model was unlikely to be correct. The other model assumes that the inherent radioresistance was equal throughout the spheroid, and that the innermost cells died before the oxygen concentration was reduced sufficiently to cause full hypoxic protection. Theoretical survival curves based on this model were generated using the measured geometries ofthe spheroids and multitarget single-hit survival theory. Acceptable agreement with the postulate that the innermost cells of spheroids die at between 0.2 and 0.4% oxygen was obtained. These data may have implications regarding the relative contributions of chronic and acute hypoxia to the fraction of hypoxic cells in tumors

  4. Supermassive Black Holes and their Host Spheroids III. The Mbh-nsph Correlation

    Science.gov (United States)

    Savorgnan, Giulia A. D.

    2016-04-01

    The Sérsic {R}1/n model is the best approximation known to date for describing the light distribution of stellar spheroidal and disk components, with the Sérsic index n providing a direct measure of the central radial concentration of stars. The Sérsic index of a galaxy’s spheroidal component, nsph, has been shown to tightly correlate with the mass of the central supermassive black hole, MBH. The {M}{BH}{--}{n}{sph} correlation is also expected from other two well known scaling relations involving the spheroid luminosity, Lsph: the {L}{sph}{--}{n}{sph} and the {M}{BH}{--}{L}{sph}. Obtaining an accurate estimate of the spheroid Sérsic index requires a careful modeling of a galaxy’s light distribution and some studies have failed to recover a statistically significant {M}{BH}{--}{n}{sph} correlation. With the aim of re-investigating the {M}{BH}{--}{n}{sph} and other black hole mass scaling relations, we performed a detailed (I.e., bulge, disks, bars, spiral arms, rings, halo, nucleus, etc.) decomposition of 66 galaxies, with directly measured black hole masses, that had been imaged at 3.6 μm with Spitzer. In this paper, the third of this series, we present an analysis of the {L}{sph}{--}{n}{sph} and {M}{BH}{--}{n}{sph} diagrams. While early-type (elliptical+lenticular) and late-type (spiral) galaxies split into two separate relations in the {L}{sph}{--}{n}{sph} and {M}{BH}{--}{L}{sph} diagrams, they reunite into a single {M}{BH}\\propto {n}{sph}3.39+/- 0.15 sequence with relatively small intrinsic scatter (ɛ ≃ 0.25 {dex}). The black hole mass appears to be closely related to the spheroid central concentration of stars, which mirrors the inner gradient of the spheroid gravitational potential.

  5. Transplantation of cord blood mesenchymal stem cells as spheroids enhances vascularization.

    Science.gov (United States)

    Bhang, Suk Ho; Lee, Seahyoung; Shin, Jung-Youn; Lee, Tae-Jin; Kim, Byung-Soo

    2012-10-01

    Despite promising results from the therapeutic use of stem cells for treating ischemic diseases, the poor survival of cells transplanted into ischemic regions is one of the major problems that undermine the efficacy of stem cell therapy. Cord blood mononuclear cells (CBMNCs) are an alternative source of mesenchymal stem cells (MSCs) without disadvantages, such as the painful and invasive harvesting procedure, of MSCs derived from bone marrow or adipose tissue. In the present study, we investigated whether the angiogenic efficacy of cord blood mesenchymal stem cells (CBMSCs) can be enhanced by grafting as spheroids in a mouse hindlimb ischemia model. Human CBMSC (hCBMSC) spheroids were prepared by using the hanging-drop method. Mouse hindlimb ischemia was induced by excising the femoral artery and its branches. After surgery, the animals were divided into no-treatment, dissociated hCBMSC, and spheroid hCBMSC groups (n=8 per group) and received corresponding hCBMSC treatments. After surgery, the ischemic hindlimbs were monitored for 4 weeks, and then, the ischemic hindlimb muscles were harvested for histological analysis. Apoptotic signaling, angiogenesis-related signal pathways, and blood vessel formation were investigated in vitro and/or in vivo. The transplantation of hCBMSCs as spheroids into mouse ischemic hindlimbs significantly improved the survival of the transplanted cells by suppressing apoptotic signaling while activating antiapoptotic signaling. Furthermore, the transplantation of hCBMSCs as spheroids significantly increased the number of microvessels and smooth muscle α-actin-positive vessels in the ischemic limbs of mice, and attenuated limb loss and necrosis. Human CBMNC can be considered an alternative source of MSC, and spheroid-based hCBMSC delivery can be considered a simple and effective strategy for enhancing the therapeutic efficacy of hCBMSCs.

  6. Sidewall coring shell

    Energy Technology Data Exchange (ETDEWEB)

    Edelman, Ya A; Konstantinov, L P; Martyshin, A N

    1966-12-12

    A sidewall coring shell consists of a housing and a detachable core catcher. The core lifter is provided with projections, the ends of which are situated in another plane, along the longitudinal axis of the lifter. The chamber has corresponding projections.

  7. Engineering fibrin hydrogels to promote the wound healing potential of mesenchymal stem cell spheroids.

    Science.gov (United States)

    Murphy, Kaitlin C; Whitehead, Jacklyn; Zhou, Dejie; Ho, Steve S; Leach, J Kent

    2017-12-01

    Mesenchymal stem cells (MSCs) secrete endogenous factors such as vascular endothelial growth factor (VEGF) and prostaglandin E2 (PGE 2 ) that promote angiogenesis, modulate the inflammatory microenvironment, and stimulate wound repair, and MSC spheroids secrete more trophic factors than dissociated, individual MSCs. Compared to injection of cells alone, transplantation of MSCs in a biomaterial can enhance their wound healing potential by localizing cells at the defect site and upregulating trophic factor secretion. To capitalize on the therapeutic potential of spheroids, we engineered a fibrin gel delivery vehicle to simultaneously enhance the proangiogenic and anti-inflammatory potential of entrapped human MSC spheroids. We used multifactorial statistical analysis to determine the interaction between four input variables derived from fibrin gel synthesis on four output variables (gel stiffness, gel contraction, and secretion of VEGF and PGE 2 ). Manipulation of the four input variables tuned fibrin gel biophysical properties to promote the simultaneous secretion of VEGF and PGE 2 by entrapped MSC spheroids while maintaining overall gel integrity. MSC spheroids in stiffer gels secreted the most VEGF, while PGE 2 secretion was highest in more compliant gels. Simultaneous VEGF and PGE 2 secretion was greatest using hydrogels with intermediate mechanical properties, as small increases in stiffness increased VEGF secretion while maintaining PGE 2 secretion by entrapped spheroids. The fibrin gel formulation predicted to simultaneously increase VEGF and PGE 2 secretion stimulated endothelial cell proliferation, enhanced macrophage polarization, and promoted angiogenesis when used to treat a wounded three-dimensional human skin equivalent. These data demonstrate that a statistical approach is an effective strategy to formulate fibrin gel formulations that enhance the wound healing potential of human MSCs. Mesenchymal stem cells (MSCs) are under investigation for wound

  8. Relationship of clonogenic cells and 'tumour-rescuing cells', modelled in irradiated spheroids in vitro

    International Nuclear Information System (INIS)

    Moore, J.V.; Hendry, J.H.

    1984-01-01

    Using the method of double negative logs (Gilbert, 1974), in which the probability of death (Pm) of a structure (e.g. spheroid, tumour or organism) after a given dose D, is related to the survival characteristics after irradiation of target cells (TRC) within the structure, the authors have reexamined the data of Durand (1975) for spheroids of V79-171 Chinese hamster cells grown in spinner culture, and of Pourreau-Schneider and Malaise (1981) for Na II human melanoma grown on agar. (U.K.)

  9. Composition of the spheroidal objects in KhN77TYuR-VD alloy

    International Nuclear Information System (INIS)

    Kotkis, M.A.; Nabutovskii, L.S.; Ostrov, A.E.; Zil'berman, A.G.

    1986-01-01

    The authors make an element analysis of the spheroidal objects in KhN77TYuR-VD alloy with the use of the energy dispersion microanalyzer with which the Stereoscan S-180 scanning electron microscope is equipped. Examples of the qualitative element analysis are shown. The results of the investigations show that the composition of the spheroidal inclusions includes nickel, chromium, titanium, iron, and also silicon and sulfur. The information obtained makes it possible to make an assumption on the mechanism of origin of these objects

  10. A possible formation scenario for dwarf spheroidal galaxies - III. Adding star formation histories to the fiducial model

    Science.gov (United States)

    Alarcón Jara, A. G.; Fellhauer, M.; Matus Carrillo, D. R.; Assmann, P.; Urrutia Zapata, F.; Hazeldine, J.; Aravena, C. A.

    2018-02-01

    Dwarf spheroidal galaxies are regarded as the basic building blocks in the formation of larger galaxies and are the most dark matter dominated systems in the Universe, known so far. There are several models that attempt to explain their formation and evolution, but they have problems modelling the formation of isolated dwarf spheroidal galaxies. Here, we will explain a possible formation scenario in which star clusters form inside the dark matter halo of a dwarf spheroidal galaxy. These star clusters suffer from low star formation efficiency and dissolve while orbiting inside the dark matter halo. Thereby, they build the faint luminous components that we observe in dwarf spheroidal galaxies. In this paper, we study this model by adding different star formation histories to the simulations and compare the results with our previous work and observational data to show that we can explain the formation of dwarf spheroidal galaxies.

  11. Spatial distribution of elements in the spheroids by prostate tumor cells using synchrotron radiation x-ray fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Leitao, Roberta G.; Santos, Carlos Antonio N.; Junior, Antonio Palumbo; Souza, Pedro A. V. R.; Canellas, Catarine G. L.; Anjos, Marcelino J.; Nasciutti, Luiz E.; Lopes, Ricardo T. [Laboratorio de Instrumentacao Nuclear, PEN/COPPE, Universidade Federal do Rio de Janeiro, Ilha do Fundao, 21941-972, Rio de Janeiro, RJ (Brazil); Laboratorio de Biotecnologia - Bioengenharia - DIPRO, Instituto Nacional de Metrologia, Normalizacao e Qualidade Industrial, Xerem. 25250-020, Duque de Caxias, RJ (Brazil); Laboratorio de Interacoes Celulares, ICB-CCS, Universidade Federal do Rio de Janeiro, Ilha do Fundao, 21941- 590, Rio de Janeiro, RJ (Brazil); Laboratorio de Instrumentacao Nuclear, PEN/COPPE, Universidade Federal do Rio de Janeiro, Ilha do Fundao, 21941-972, Rio de Janeiro, RJ (Brazil); Laboratorio de Interacoes Celulares, ICB-CCS, Universidade Federal do Rio de Janeiro, Ilha do Fundao, 21941- 590, Rio de Janeiro, RJ (Brazil); Laboratorio de Instrumentacao Nuclear, PEN/COPPE, Universidade Federal do Rio de Janeiro, Ilha do Fundao, 21941-972, Rio de Janeiro, RJ (Brazil)

    2012-05-17

    The formation of three-dimensional cell microspheres such as spheroids has attracted attention as a useful culture technique. In this study, we investigated the trace elemental distribution (mapping) in spheroids derived from tissue prostate cancer (PCa). The measurements were performed in standard geometry of 45 deg. incidence, exciting with a white beam and using an optical capillary with 20 {mu}m diameter collimation in the XRF beam line at the Synchrotron Light National Laboratory (Campinas, Brazil). The results showed that most elements analyzed presented non-uniform distribution. P, S and Cl showed similar elemental distribution in all the samples analyzed. K, Ca, Fe, and Cu showed different elemental distribution for the spheroids analyzed. Zinc presented more intense distributions in the spheroid central region for all spheroids analyzed.

  12. Spatial distribution of elements in the spheroids by prostate tumor cells using synchrotron radiation X-ray fluorescence

    International Nuclear Information System (INIS)

    Leitao, Roberta G.; Canellas, Catarine G.L.; Anjos, Marcelino J.; Lopes, Ricardo T.; Santos, Carlos Antonio N.; Palumbo Junior, Antonio; Souza, Pedro A.V.R.; Nasciutti, Luiz E.

    2011-01-01

    The formation of three-dimensional cell microspheres such as spheroids has attracted attention as a useful culture technique. In this study, we investigated the trace elemental distribution (mapping) in spheroids derived from tissue prostate cancer (PCa). The measurements were performed in standard geometry of 45 deg incidence, exciting with a white beam and using an optical capillary with 20 μm diameter collimation in the XRF beam line at the Synchrotron Light National Laboratory (Campinas, Brazil). The results showed that most elements analyzed presented non-uniform distribution. P, S and Cl showed similar elemental distribution in all the samples analyzed. K, Ca, Fe, and Cu showed different elemental distribution for the spheroids analyzed. Zinc presented more intense distributions in the spheroid central region for all spheroids analyzed. (author)

  13. Spatial distribution of elements in the spheroids by prostate tumor cells using synchrotron radiation x-ray fluorescence

    International Nuclear Information System (INIS)

    Leitao, Roberta G.; Santos, Carlos Antonio N.; Junior, Antonio Palumbo; Souza, Pedro A. V. R.; Canellas, Catarine G. L.; Anjos, Marcelino J.; Nasciutti, Luiz E.; Lopes, Ricardo T.

    2012-01-01

    The formation of three-dimensional cell microspheres such as spheroids has attracted attention as a useful culture technique. In this study, we investigated the trace elemental distribution (mapping) in spheroids derived from tissue prostate cancer (PCa). The measurements were performed in standard geometry of 45 deg. incidence, exciting with a white beam and using an optical capillary with 20 μm diameter collimation in the XRF beam line at the Synchrotron Light National Laboratory (Campinas, Brazil). The results showed that most elements analyzed presented non-uniform distribution. P, S and Cl showed similar elemental distribution in all the samples analyzed. K, Ca, Fe, and Cu showed different elemental distribution for the spheroids analyzed. Zinc presented more intense distributions in the spheroid central region for all spheroids analyzed.

  14. The increase in radioresistance of Chinese hamster cells cultured as spheroids is correlated to changes in nuclear morphology

    International Nuclear Information System (INIS)

    Gordon, D.J.; Milner, A.E.; Beaney, R.P.; Grdina, D.J.; Vaughan, A.T.

    1990-01-01

    Chinese hamster V79 cells grown as spheroids in roller culture are more radioresistant than those grown as monolayers. The supercoiled structure of chromatin, as salt-extracted nucleoids, has been examined using flow cytometry. Irradiated viable cells from spheroid culture contain restraints to supercoil relaxation that are absent in monolayer cells. Further analysis of the chromatin organization from each growth form shows that the radioresistant spheroid cells contain a DNA-protein matrix that is more resistant to detergent-induced degradation. The increase in structural integrity may be due to the retention of a 55-60 kDa protein that is apparent in the nucleoids of spheroid, but not monolayer cells. The increase in structural integrity of the spheroid cells may explain their greater radioresistance by providing a more stable platform for high-fidelity DNA damage repair

  15. Spatial distribution of elements in the spheroids by prostate tumor cells using synchrotron radiation X-ray fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Leitao, Roberta G.; Canellas, Catarine G.L.; Anjos, Marcelino J.; Lopes, Ricardo T. [Universidade Federal do Rio de Janeiro (PEN/COPPE/UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-Graduacao de Engenharia. Programa de Energia Nuclear; Santos, Carlos Antonio N. [Instituto Nacional de Metrologia, Normalizacao e Qualidade Industrial (INMETRO), Duque de Caxias, RJ (Brazil). Lab. de Biotecnologia - Bioengenharia; Palumbo Junior, Antonio; Souza, Pedro A.V.R.; Nasciutti, Luiz E., E-mail: nasciutt@ufrj.b [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Lab. de Interacoes Celulares

    2011-07-01

    The formation of three-dimensional cell microspheres such as spheroids has attracted attention as a useful culture technique. In this study, we investigated the trace elemental distribution (mapping) in spheroids derived from tissue prostate cancer (PCa). The measurements were performed in standard geometry of 45 deg incidence, exciting with a white beam and using an optical capillary with 20 {mu}m diameter collimation in the XRF beam line at the Synchrotron Light National Laboratory (Campinas, Brazil). The results showed that most elements analyzed presented non-uniform distribution. P, S and Cl showed similar elemental distribution in all the samples analyzed. K, Ca, Fe, and Cu showed different elemental distribution for the spheroids analyzed. Zinc presented more intense distributions in the spheroid central region for all spheroids analyzed. (author)

  16. Phase field study of interfacial diffusion-driven spheroidization in a composite comprized of two mutually insoluble phases

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Liang [Ames Laboratory; Russell, Alan [Ames Laboratory

    2014-03-27

    The phase field approach is a powerful computational technique to simulate morphological and microstructural evolution at the mesoscale. Spheroidization is a frequently observed morphological change of mesoscale heterogeneous structures during annealing. In this study, we used the diffuse interface phase field method to investigate the interfacial diffusion-driven spheroidization of cylindrical rod structures in a composite comprised of two mutually insoluble phases in a two-dimensional case. Perturbation of rod radius along a cylinder's axis has long been known to cause the necessary chemical potential gradient that drives spheroidization of the rod by Lord Rayleigh's instability theory. This theory indicates that a radius perturbation wavelength larger than the initial rod circumference would lead to cylindrical spheroidization. We investigated the effect of perturbation wavelength, interfacial energy, volume diffusion, phase composition, and interfacial percentage on the kinetics of spheroidization. The results match well with both the Rayleigh's instability criterion and experimental observations.

  17. Penetration and binding of monoclonal antibody in human osteosarcoma multicell spheroids. Comparison of confocal laser scanning microscopy and autoadiography

    International Nuclear Information System (INIS)

    Hjelstuen, M.H.; Rasch-Halvorsen, K.; Brekken, C.; Bruland, Oe.; Davies, C. de L.

    1996-01-01

    Penetration and binding of monoclonal antibody (MAb) in multicell osteosarcoma spheroids have been studied by autoradiography and confocal laser scanning microscopy (CLSM). Optical sectioning of the 3-dimensional spheroids was performed by CLSM. Owing to attenuation of fluorescence intensity, FITC-labelled MAb could not be detected at depths greater than 60 μm within the spheroids. The antibody uptake seen in autoradiographs and CLSM images 60 μm within the spheroids were essentially identical. MAb had reached all parts of the spheroids within 6 h. Quantitative measurements of the fluorescence intensity of FITC-labelled MAb seen in confocal images and measurements of MAb bound per cell using flow cytometry, showed that maximum uptake was reached after 6 h. The possibility to perform both quantatitive and qualitative measurements makes CLSM a promising method for studying antibody uptake in thick tissue samples. (orig.)

  18. Stability of charged thin shells

    International Nuclear Information System (INIS)

    Eiroa, Ernesto F.; Simeone, Claudio

    2011-01-01

    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.

  19. Temporal structures in shell models

    DEFF Research Database (Denmark)

    Okkels, F.

    2001-01-01

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

  20. Monitoring the effects of doxorubicin on 3D-spheroid tumor cells in real-time

    Directory of Open Access Journals (Sweden)

    Baek N

    2016-11-01

    Full Text Available NamHuk Baek,1,* Ok Won Seo,1,* MinSung Kim,1 John Hulme,2 Seong Soo A An2 1Department of R & D, NanoEntek Inc., Seoul, Republic of Korea; 2Department of BioNano Technology Gachon University, Gyeonggi-do, Republic of Korea *These authors contributed equally to this work Abstract: Recently, increasing numbers of cell culture experiments with 3D spheroids presented better correlating results in vivo than traditional 2D cell culture systems. 3D spheroids could offer a simple and highly reproducible model that would exhibit many characteristics of natural tissue, such as the production of extracellular matrix. In this paper numerous cell lines were screened and selected depending on their ability to form and maintain a spherical shape. The effects of increasing concentrations of doxorubicin (DXR on the integrity and viability of the selected spheroids were then measured at regular intervals and in real-time. In total 12 cell lines, adenocarcinomic alveolar basal epithelial (A549, muscle (C2C12, prostate (DU145, testis (F9, pituitary epithelial-like (GH3, cervical cancer (HeLa, HeLa contaminant (HEp2, embryo (NIH3T3, embryo (PA317, neuroblastoma (SH-SY5Y, osteosarcoma U2OS, and embryonic kidney cells (293T, were screened. Out of the 12, 8 cell lines, NIH3T3, C2C12, 293T, SH-SY5Y, A549, HeLa, PA317, and U2OS formed regular spheroids and the effects of DXR on these structures were measured at regular intervals. Finally, 5 cell lines, A549, HeLa, SH-SY5Y, U2OS, and 293T, were selected for real-time monitoring and the effects of DXR treatment on their behavior were continuously recorded for 5 days. A potential correlation regarding the effects of DXR on spheroid viability and ATP production was measured on days 1, 3, and 5. Cytotoxicity of DXR seemed to occur after endocytosis, since the cellular activities and ATP productions were still viable after 1 day of the treatment in all spheroids, except SH-SY5Y. Both cellular activity and ATP production were

  1. Modeling photopolarimetric characteristics of comet dust as a polydisperse mixture of polyshaped rough spheroids

    Science.gov (United States)

    Kolokolova, L.; Das, H.; Dubovik, O.; Lapyonok, T.

    2013-12-01

    It is widely recognized now that the main component of comet dust is aggregated particles that consist of submicron grains. It is also well known that cometary dust obey a rather wide size distribution with abundant particles whose size reaches dozens of microns. However, numerous attempts of computer simulation of light scattering by comet dust using aggregated particles have not succeeded to consider particles larger than a couple of microns due to limitations in the memory and speed of available computers. Attempts to substitute aggregates by polydisperse solid particles (spheres, spheroids, cylinders) could not consistently reproduce observed angular and spectral characteristics of comet brightness and polarization even in such a general case as polyshaped (i.e. containing particles of a variety of aspect ratios) mixture of spheroids (Kolokolova et al., In: Photopolarimetry in Remote Sensing, Kluwer Acad. Publ., 431, 2004). In this study we are checking how well cometary dust can be modeled using modeling tools for rough spheroids. With this purpose we use the software package described in Dubovik et al. (J. Geophys. Res., 111, D11208, doi:10.1029/2005JD006619d, 2006) that allows for a substantial reduction of computer time in calculating scattering properties of spheroid mixtures by means of using pre-calculated kernels - quadrature coefficients employed in the numerical integration of spheroid optical properties over size and shape. The kernels were pre-calculated for spheroids of 25 axis ratios, ranging from 0.3 to 3, and 42 size bins within the size parameter range 0.01 - 625. This software package has been recently expanded with the possibility of simulating not only smooth but also rough spheroids that is used in present study. We consider refractive indexes of the materials typical for comet dust: silicate, carbon, organics, and their mixtures. We also consider porous particles accounting on voids in the spheroids through effective medium approach. The

  2. Formation of stable small cell number three-dimensional ovarian cancer spheroids using hanging drop arrays for preclinical drug sensitivity assays.

    Science.gov (United States)

    Raghavan, Shreya; Ward, Maria R; Rowley, Katelyn R; Wold, Rachel M; Takayama, Shuichi; Buckanovich, Ronald J; Mehta, Geeta

    2015-07-01

    Ovarian cancer grows and metastasizes from multicellular spheroidal aggregates within the ascites fluid. Multicellular tumor spheroids are therefore physiologically significant 3D in vitro models for ovarian cancer research. Conventional hanging drop cultures require high starting cell numbers, and are tedious for long-term maintenance. In this study, we generate stable, uniform multicellular spheroids using very small number of ovarian cancer cells in a novel 384 well hanging drop array platform. We used novel tumor spheroid platform and two ovarian cancer cell lines (A2780 and OVCAR3) to demonstrate the stable incorporation of as few as 10 cells into a single spheroid. Spheroids had uniform geometry, with projected areas (42.60×10(3)μm-475.22×10(3)μm(2) for A2780 spheroids and 37.24×10(3)μm(2)-281.01×10(3)μm(2) for OVCAR3 spheroids) that varied as a function of the initial cell seeding density. Phalloidin and nuclear stains indicated cells formed tightly packed spheroids with demarcated boundaries and cell-cell interaction within spheroids. Cells within spheroids demonstrated over 85% viability. 3D tumor spheroids demonstrated greater resistance (70-80% viability) to cisplatin chemotherapy compared to 2D cultures (30-50% viability). Ovarian cancer spheroids can be generated from limited cell numbers in high throughput 384 well plates with high viability. Spheroids demonstrate therapeutic resistance relative to cells in traditional 2D culture. Stable incorporation of low cell numbers is advantageous when translating this research to rare patient-derived cells. This system can be used to understand ovarian cancer spheroid biology, as well as carry out preclinical drug sensitivity assays. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Shells on elastic foundations

    International Nuclear Information System (INIS)

    Das, Y.C.; Kedia, K.K.

    1977-01-01

    No realistic analytical work in the area of Shells on Elastic Foundations has been reported in the literature. Various foundation models have been proposed by several authors. These models involve one or more than one parameters to characterise the foundation medium. Some of these models cannot be used to derive the basic equations governing the behaviour of shells on elastic foundations. In the present work, starting from an elastic continuum hypothesis, a mathematical model for foundation has been derived in curvilinear orthogonal coordinates by the help of principle of virtual displacements, treating one of the virtual displacements as known to satisfy certain given conditions at its edge surfaces. In this model, several foundation parameters can be considered and it can also be used for layered medium of both finite and infinite thickness. (Auth.)

  4. Flames High Resolution Spectroscopy of RGB Stars in the Carina Dwarf Spheroidal Galaxy

    NARCIS (Netherlands)

    Lemasle, B.; Hill, V.; Tolstoy, E.; Venn, K.; Koleva, M; Prugniel, P; Vauglin,

    Carina is a small and faint classical dwarf spheroidal galaxy in the halo of the Milky Way with a highly episodic star formation history (e.g., Hurley-Keller et al. 1998). Using VLT/FLAMES in high resolution mode, we significantly increase the sample of stars with abundance determinations in Carina,

  5. VLT/FLAMES spectroscopy of red giant branch stars in the Fornax dwarf spheroidal galaxy

    NARCIS (Netherlands)

    Lemasle, B.; de Boer, T.J.L.; Hill, V.; Tolstoy, E.; Irwin, M.J.; Jablonka, P.; Venn, K.; Battaglia, G.; Starkenburg, E.; Shetrone, M.; Letarte, B.; François, P.; Helmi, A.; Primas, F.; Kaufer, A.; Szeifert, T.

    2014-01-01

    Context. Fornax is one of the most massive dwarf spheroidal galaxies in the Local Group. The Fornax field star population is dominated by intermediate age stars but star formation was going on over almost its entire history. It has been proposed that Fornax experienced a minor merger event. Aims.

  6. Chemical composition of extremely metal-poor stars in the Sextans dwarf spheroidal galaxy

    NARCIS (Netherlands)

    Aoki, W.; Arimoto, N.; Sadakane, K.; Tolstoy, E.; Battaglia, G.; Jablonka, P.; Shetrone, M.; Letarte, B.; Irwin, M.; Hill, V.; Francois, P.; Venn, K.; Primas, F.; Helmi, A.; Kaufer, A.; Tafelmeyer, M.; Szeifert, T.; Babusiaux, C.

    Context. Individual stars in dwarf spheroidal galaxies around the Milky Way Galaxy have been studied both photometrically and spectroscopically. Extremely metal-poor stars among them are very valuable because they should record the early enrichment in the Local Group. However, our understanding of

  7. Internal kinematics and dynamical models of dwarf spheroidal galaxies around the Milky Way

    NARCIS (Netherlands)

    Battaglia, Giuseppina; Helmi, Amina; Breddels, Maarten

    We review our current understanding of the internal dynamical properties of the dwarf spheroidal galaxies surrounding the Milky Way. These are the most dark matter dominated galaxies, and as such may be considered ideal laboratories to test the current concordance cosmological model, and in

  8. VLT/UVES abundances in four nearby dwarf spheroidal galaxies. II. Implications for understanding galaxy evolution

    NARCIS (Netherlands)

    Tolstoy, E; Venn, KA; Shetrone, M; Primas, F; Hill, [No Value; Kaufer, A; Szeifert, T

    We have used the Ultraviolet Visual-Echelle Spectrograph (UVES) on Kueyen (UT2) of the Very Large Telescope to take spectra of 15 individual red giant stars in the centers of four nearby dwarf spheroidal galaxies (dSph's) : Sculptor, Fornax, Carina, and Leo I. We measure the abundance variations of

  9. A new study of stellar substructures in the Fornax dwarf spheroidal galaxy

    NARCIS (Netherlands)

    de Boer, T. J. L.; Tolstoy, E.; Saha, A.; Olszewski, E. W.

    Using deep V, B - V wide-field photometry, we have conducted a new study of stellar over-densities in the Fornax dwarf spheroidal galaxy by determining detailed star formation histories from colour-magnitude diagram analysis. We have concentrated on the relatively young stellar component ( We have

  10. Cardiac spheroids as promising in vitro models to study the human heart microenvironment

    DEFF Research Database (Denmark)

    Polonchuk, Liudmila; Chabria, Mamta; Badi, Laura

    2017-01-01

    Three-dimensional in vitro cell systems are a promising alternative to animals to study cardiac biology and disease. We have generated three-dimensional in vitro models of the human heart ("cardiac spheroids", CSs) by co-culturing human primary or iPSC-derived cardiomyocytes, endothelial cells an...

  11. Three-dimensional spheroid culture promotes odonto/osteoblastic differentiation of dental pulp cells.

    Science.gov (United States)

    Yamamoto, Mioko; Kawashima, Nobuyuki; Takashino, Nami; Koizumi, Yu; Takimoto, Koyo; Suzuki, Noriyuki; Saito, Masahiro; Suda, Hideaki

    2014-03-01

    Three-dimensional (3D) spheroid culture is a method for creating 3D aggregations of cells and their extracellular matrix without a scaffold mimicking the actual tissues. The aim of this study was to evaluate the effects of 3D spheroid culture on the phenotype of immortalized mouse dental papilla cells (MDPs) that have the ability to differentiate into odontoblasts. We cultured MDPs for 1, 3, 7, and 14 days in 96-well low-attachment culture plates for 3D spheroid culture or flat-bottomed plates for two-dimensional (2D) monolayer culture. Cell proliferation and apoptosis were detected by immunohistochemical staining of Ki67 and cleaved caspase-3, respectively. Hypoxia was measured by the hypoxia probe LOX-1. Odonto/osteoblastic differentiation marker gene expression was evaluated by quantitative PCR. We also determined mineralized nodule formation, alkaline phosphatase (ALP) activity, and dentine matrix protein-1 (DMP1) expression. Vinculin and integrin signalling-related proteins were detected immunohistochemically. Odonto/osteoblastic marker gene expression and mineralized nodule formation were significantly up-regulated in 3D spheroid-cultured MDPs compared with those in 2D monolayer-cultured MDPs (podonto/osteoblastic differentiation of MDPs, which may be mediated by integrin signalling. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Autophagy Protects from Trastuzumab-Induced Cytotoxicity in HER2 Overexpressing Breast Tumor Spheroids.

    Directory of Open Access Journals (Sweden)

    Cristina E Rodríguez

    Full Text Available Multicellular tumor spheroids represent a 3D in vitro model that mimics solid tumor essential properties including assembly and development of extracellular matrix and nutrient, oxygen and proliferation gradients. In the present study, we analyze the impact of 3D spatial organization of HER2-overexpressing breast cancer cells on the response to Trastuzumab. We cultured human mammary adenocarcinoma cell lines as spheroids with the hanging drop method and we observed a gradient of proliferating, quiescent, hypoxic, apoptotic and autophagic cells towards the inner core. This 3D organization decreased Trastuzumab sensitivity of HER2 over-expressing cells compared to monolayer cell cultures. We did not observe apoptosis induced by Trastuzumab but found cell arrest in G0/G1 phase. Moreover, the treatment downregulated the basal apoptosis only found in tumor spheroids, by eliciting protective autophagy. We were able to increase sensitivity to Trastuzumab by autophagy inhibition, thus exposing the interaction between apoptosis and autophagy. We confirmed this result by developing a resistant cell line that was more sensitive to autophagy inhibition than the parental BT474 cells. In summary, the development of Trastuzumab resistance relies on the balance between death and survival mechanisms, characteristic of 3D cell organization. We propose the use of spheroids to further improve the understanding of Trastuzumab antitumor activity and overcome resistance.

  13. Can physical stellar collisions explain the blue stragglers in the dwarf spheroidal galaxies?

    International Nuclear Information System (INIS)

    Leonard, P.J.T.

    1993-01-01

    The hypothesis that the blue stragglers in the dwarf spheroidal galaxie have a collisional origin is considered. If all of the dark matter in these galaxies is in the form of low-mass stars and the binary frequency is ≅ 50%, then it is quite possible that ≅ 10% to 20% of their blue stragglers have been produced by physical stellar collisions

  14. Three-dimensional in vitro cancer spheroid models for Photodynamic Therapy: Strengths and Opportunities

    Science.gov (United States)

    Evans, Conor

    2015-03-01

    Three dimensional, in vitro spheroid cultures offer considerable utility for the development and testing of anticancer photodynamic therapy regimens. More complex than monolayer cultures, three-dimensional spheroid systems replicate many of the important cell-cell and cell-matrix interactions that modulate treatment response in vivo. Simple enough to be grown by the thousands and small enough to be optically interrogated, spheroid cultures lend themselves to high-content and high-throughput imaging approaches. These advantages have enabled studies investigating photosensitizer uptake, spatiotemporal patterns of therapeutic response, alterations in oxygen diffusion and consumption during therapy, and the exploration of mechanisms that underlie therapeutic synergy. The use of quantitative imaging methods, in particular, has accelerated the pace of three-dimensional in vitro photodynamic therapy studies, enabling the rapid compilation of multiple treatment response parameters in a single experiment. Improvements in model cultures, the creation of new molecular probes of cell state and function, and innovations in imaging toolkits will be important for the advancement of spheroid culture systems for future photodynamic therapy studies.

  15. Stem Cell Spheroids and Ex Vivo Niche Modeling: Rationalization and Scaling-Up.

    Science.gov (United States)

    Chimenti, Isotta; Massai, Diana; Morbiducci, Umberto; Beltrami, Antonio Paolo; Pesce, Maurizio; Messina, Elisa

    2017-04-01

    Improved protocols/devices for in vitro culture of 3D cell spheroids may provide essential cues for proper growth and differentiation of stem/progenitor cells (S/PCs) in their niche, allowing preservation of specific features, such as multi-lineage potential and paracrine activity. Several platforms have been employed to replicate these conditions and to generate S/PC spheroids for therapeutic applications. However, they incompletely reproduce the niche environment, with partial loss of its highly regulated network, with additional hurdles in the field of cardiac biology, due to debated resident S/PCs therapeutic potential and clinical translation. In this contribution, the essential niche conditions (metabolic, geometric, mechanical) that allow S/PCs maintenance/commitment will be discussed. In particular, we will focus on both existing bioreactor-based platforms for the culture of S/PC as spheroids, and on possible criteria for the scaling-up of niche-like spheroids, which could be envisaged as promising tools for personalized cardiac regenerative medicine, as well as for high-throughput drug screening.

  16. Electromagnetic waves in irregular multilayered spheroidal structures of finite conductivity: full wave solutions

    International Nuclear Information System (INIS)

    Bahar, E.

    1976-01-01

    The propagation of electromagnetic waves excited by electric dipoles oriented along the axis of multilayered spheroidal structures of finite conductivity is investigated. The electromagnetic parameters and the thickness of the layers of the structure are assumed to be functions of the latitude. In the analysis, electric and magnetic field transforms that constitute a discrete and a continuous spectrum of spherical waves are used to provide a suitable basis for the expansion of the electromagnetic fields at any point in the irregular spheroidal structure. For spheroidal structures with good conducting cores, the terms in the solutions associated with the continuous part of the wave spectrum vanish. In general, however, when the skin depth for the core is large compared to its dimensions or when the sources are located in the core of the structure and propagation in the core is of special interest, the contribution from the continuous part of the wave spectrum cannot be neglected. At each interface between the layers of the irregular spheroidal structure, exact boundary conditions are imposed. Since the terms of the field expansions in the irregular structure do not individually satisfy the boundary conditions, Maxwell's equations are reduced to sets of coupled ordinary first-order differential equations for the wave amplitudes. The solutions are shown to satisfy the reciprocity relationships in electromagnetic theory. The analysis may be applied to problems of radio wave propagation in a nonuniform model of the earth-ionosphere waveguide, particularly when focusing effects at the antipodes are important

  17. Ground eigenvalue and eigenfunction of a spin-weighted spheroidal wave equation in low frequencies

    Institute of Scientific and Technical Information of China (English)

    Tang Wen-Lin; Tian Gui-Hua

    2011-01-01

    Spin-weighted spheroidal wave functions play an important role in the study of the linear stability of rotating Kerr black holes and are studied by the perturbation method in supersymmetric quantum mechanics. Their analytic ground eigenvalues and eigenfunctions are obtained by means of a series in low frequency. The ground eigenvalue and eigenfunction for small complex frequencies are numerically determined.

  18. Detailed Studies of the Sculptor Dwarf Spheroidal Galaxy in the Milky Way halo

    NARCIS (Netherlands)

    Tolstoy, Eline

    In and around the Milky Way halo there are a number of low mass low luminosity dwarf galaxies. Several of these systems have been studied in great detail. I describe recent photometric and spectroscopic studies of the Sculptor dwarf spheroidal galaxy made as part of the DART survey of nearby dwarf

  19. Dynamics of Small Inertia-Free Spheroidal Particles in a Turbulent Channel Flow

    Science.gov (United States)

    Challabotla, Niranjan Reddy; Zhao, Lihao; Andersson, Helge I.; Department of Energy; Process Engineering Team

    2015-11-01

    The study of small non-spherical particles suspended in turbulent fluid flows is of interest in view of the potential applications in industry and the environment. In the present work, we investigated the dynamics of inertia-free spheroidal particles suspended in fully-developed turbulent channel flow at Re τ = 180 by using the direct numerical simulations (DNS) for the Eulerian fluid phase coupled with the Lagrangian point-particle tracking. We considered inertia-free spheroidal particles with a wide range of aspect ratios from 0.01 to 50, i.e. from flat disks to long rods. Although the spheroids passively translate along with the fluid, the particle orientation and rotation strongly depend on the particle shape. The flattest disks were preferentially aligned with their symmetry axis normal to the wall, whereas the longest rods aligned parallel to the wall. Strong mean rotational spin was observed for spherical particles and this has been damped with increasing asphericity both for rod-like and disk-like spheroids. The anisotropic mean and fluctuating fluid vorticity resulted in particle spin anisotropies which exhibited a complex dependence on the particle asphericty. The Research Council of Norway, Notur and COST Action FP1005 are gratefully acknowledged.

  20. Influence of boron on ferrite formation in copper-added spheroidal graphite cast iron

    Directory of Open Access Journals (Sweden)

    Ying Zou

    2014-07-01

    Full Text Available This paper reviews the original work of the authors published recently, describing the influence of B on the matrix of the Cuadded spheroidal graphite cast iron. The effect of Cu has been corrected as a ferrite formation promoter in the matrix of the grey cast iron by the usage of high-purity material. Also, this paper focuses on the ferrite formation and the observation of the Cu distribution in the B-added and B-free Cu-containing spheroidal graphite cast iron. The Cu film on the spheroidal graphite can be successfully observed in the B-free sample using a special etching method. However, in the B-added sample, no Cu film could be found, while the secondary graphite was formed on the surface of the spheroidal graphite. The interaction between B and Cu is stressed as a peculiar phenomenon by the employment of a contrast experiment of B and Mn. The heat treatment could make Cu precipitate more significantly in the eutectic cells and in the matrix in the form of large Cu particles because of the limited solubility of Cu.

  1. Porous Nb-Ti based alloy produced from plasma spheroidized powder

    Science.gov (United States)

    Li, Qijun; Zhang, Lin; Wei, Dongbin; Ren, Shubin; Qu, Xuanhui

    Spherical Nb-Ti based alloy powder was prepared by the combination of plasma spheroidization and mechanical alloying. Phase constituents, microstructure and surface state of the powder, and pore characteristics of the resulting porous alloy were investigated. The results show that the undissolved W and V in the mechanically alloyed powder is fully alloyed after spheroidization, and single β phase is achieved. Particle size of the spheroidized powder is in the range of 20-110 μm. With the decrease of particle size, a transformation from typical dendrite solidification structure to fine cell microstructure occurs. The surface of the spheroidized powder is coated by a layer of oxides consisting mainly of TiO2 and Nb2O5. Probabilities of sinter-neck formation and particle coalescence increases with increasing sintering temperature. Porous skeleton with relatively homogeneous pore distribution and open pore channel is formed after vacuum sintering at 1700 °C, and the porosity is 32%. The sintering kinetic analysis indicates that grain boundary diffusion is the primary mass transport mechanism during sintering process.

  2. Numerical Simulation of Spheroidization Process of TiAl Alloy Powders in Radio Frequency Plasma

    Directory of Open Access Journals (Sweden)

    ZHU Langping

    2017-06-01

    Full Text Available A numerical simulation method was used to study the radio frequency plasma spheroidization process of TiAl alloy powder. The effects of velocity field and temperature field on the motion trajectory and mass change of TiAl alloy powder with different particle size were analyzed.The results show that the temperature of powder particles increases rapidly under high temperature plasma, surface evaporation cause the reduction of particle size, and particles with small size tend to evaporate quickly. The motion trajectory of particles with different sizes in the lower end of the cooling tube is different obviously, small particles tend to enter the air outlet,while the larger particles are easy to fall down to the bottom of the cooling tube to be collected. Increasing air flow rate can improve the velocity of air flow in the spheroidizing system, causing larger particles to be taken away by the air, resulting in yield reduction. The simulation results of TiAl alloy powder spheroidization are close to the experimental results refer to parameters such as powder size distribution, average particle size and powder yield, and the model is in good accordance with the actual process of the spheroidization.

  3. THE STELLAR SPHEROID, THE DISK, AND THE DYNAMICS OF THE COSMIC WEB

    International Nuclear Information System (INIS)

    Domínguez-Tenreiro, R.; Obreja, A.; Brook, C. B.; Martínez-Serrano, F. J.; Serna, A.; Stinson, G.

    2015-01-01

    Models of the advanced stages of gravitational instability predict that baryons that form the stellar populations of current galaxies at z = 0 displayed a web-like structure at high z, as part of the cosmic web (CW). We explore details of these predictions using cosmological hydrodynamical simulations. When the stellar populations of the spheroid and disk components of simulated late-type galaxies are traced back separately to high zs we found CW-like structures where spheroid progenitors are more evolved than disk progenitors. The distinction between the corresponding stellar populations, as driven by their specific angular momentum content j, can be explained in terms of the CW evolution, extended to two processes occurring at lower z. First, the spheroid progenitors strongly lose j at collapse, which contrasts with the insignificant j loss of the disk progenitors. The second is related to the lack of alignment, at assembly, between the spheroid-to-be material and the already settled proto-disk, in contrast to the alignment of disk-to-be material, in some cases resulting from circumgalactic, disk-induced gravitational torques. The different final outcomes of these low-z processes have their origins in the different initial conditions driven by the CW dynamics

  4. Photometric analyses of abundances in dwarf spheroidal galaxies and globular clusters

    International Nuclear Information System (INIS)

    Light, R.M.

    1988-01-01

    This study investigated the abundance characteristics of several dwarf spheroidal galaxies. The chemical properties of stars in these galaxies are tracers of the origin and evolution of their stellar populations, and thus can provide constraints on the theories of their formation. To derive this abundance information, photometric observations of stars in a sample of globular clusters, covering a large range in metallicity, were analyzed. Parameters describing the position of the red giant branch were found to correlate very well with cluster metallicity over a large range in abundance. These measurements, made in the Thuan-Gunn photometry system, provide ranking schemes which are, with accurate photometry, more sensitive to changes in metallicity than similar broadband BV parameters. The relations were used to derive an improved estimate of the metallicity of cluster NGC 5053. These metallicity relations were used to analyze the Thuan-Gunn system photometry produced for the Sculptor, Ursa Minor, and Carina galaxies. The excellent agreement between their metallicities and those from other previous studies indicates that globular cluster red giant branch parameters are very useful in ranking dwarf spheroidal populations by metallicity. Together with other galaxian data, strong correlations can be seen between the mean metallicities and dispersions in metallicity and the luminosities of the dwarf spheroidal galaxies. These trends also seem to apply to members of the dwarf elliptical class of galaxies. The ramifications that these correlations and the existence of a metallicity gradient in Sculptor have on the formation of the dwarf spheroidals are discussed

  5. Daunorubicin and doxorubicin but not BCNU have deleterious effects on organotypic multicellular spheroids of gliomas

    NARCIS (Netherlands)

    Kaaijk, P.; Troost, D.; de Boer, O. J.; van Amstel, P.; Bakker, P. J.; Leenstra, S.; Bosch, D. A.

    1996-01-01

    In the present study organotypic multicellular spheroids (OMS) were used to study the effects of chemotherapeutic agents on malignant gliomas. Compared with the frequently used cell line models, OMS have several advantages with respect to the preservation of the cellular heterogeneity and the

  6. Impact of a small ellipticity on the sustainability condition of developed turbulence in a precessing spheroid

    Science.gov (United States)

    Horimoto, Yasufumi; Simonet-Davin, Gabriel; Katayama, Atsushi; Goto, Susumu

    2018-04-01

    We experimentally investigate the flow transition to developed turbulence in a precessing spheroid with a small ellipticity. Fully developed turbulence appears through a subcritical transition when we fix the Reynolds number (the spin rate) and gradually increase the Poincaré number (the precession rate). In the transitional range of the Poincaré number, two qualitatively different turbulent states (i.e., fully developed turbulence and quiescent turbulence with a spin-driven global circulation) are stable and they are connected by a hysteresis loop. This discontinuous transition is in contrast to the continuous transition in a precessing sphere, for which neither bistable turbulent states nor hysteresis loops are observed. The small ellipticity of the container makes the global circulation of the confined fluid more stable, and it requires much stronger precession of the spheroid, than a sphere, for fully developed turbulence to be sustained. Nevertheless, once fully developed turbulence is sustained, its flow structures are almost identical in the spheroid and sphere. The argument [Lorenzani and Tilgner, J. Fluid Mech. 492, 363 (2003), 10.1017/S002211200300572X; Noir et al., Geophys. J. Int. 154, 407 (2003), 10.1046/j.1365-246X.2003.01934.x] on the basis of the analytical solution [Busse, J. Fluid Mech. 33, 739 (1968), 10.1017/S0022112068001655] of the steady global circulation in a weak precession range well describes the onset of the fully developed turbulence in the spheroid.

  7. Design of Online Spheroidization Process for 1.0C-1.5Cr Bearing Steel and Microstructure Analysis

    Science.gov (United States)

    Li, Zhen-Xing; Li, Chang-Sheng; Ren, Jin-Yi; Li, Bin-Zhou; Suh, Dong-Woo

    2018-02-01

    Using thermo-mechanical control process, the online spheroidization annealing process of 1.0C-1.5Cr bearing steel was designed. Apart from intercritical online spheroidization (IS), a novel subcritical online spheroidization (SS) process was proposed, which is characterized by water-cooling to around 773 K (500 °C) after the final rolling pass, and then directly reheating to 973 K (700 °C) for isothermal holding. Compared with the results from the traditional offline spheroidization (TS) process, the size of spheroidized carbides is similar in both the TS and IS processes, whereas it is much smaller in the SS process. After spheroidization annealing, microstructure evolution during austenitization and quenching treatment was examined. It is shown that the refining of spheroidized carbides accelerates the dissolution of carbides during the austenitizing process, and decreases the size of undissolved carbides. In addition, the SS process can obtain finer prior austenite grain after quenching, which contributes to the enhancement of final hardness.

  8. Micro-environmental mechanical stress controls tumor spheroid size and morphology by suppressing proliferation and inducing apoptosis in cancer cells.

    Directory of Open Access Journals (Sweden)

    Gang Cheng

    Full Text Available Compressive mechanical stress produced during growth in a confining matrix limits the size of tumor spheroids, but little is known about the dynamics of stress accumulation, how the stress affects cancer cell phenotype, or the molecular pathways involved.We co-embedded single cancer cells with fluorescent micro-beads in agarose gels and, using confocal microscopy, recorded the 3D distribution of micro-beads surrounding growing spheroids. The change in micro-bead density was then converted to strain in the gel, from which we estimated the spatial distribution of compressive stress around the spheroids. We found a strong correlation between the peri-spheroid solid stress distribution and spheroid shape, a result of the suppression of cell proliferation and induction of apoptotic cell death in regions of high mechanical stress. By compressing spheroids consisting of cancer cells overexpressing anti-apoptotic genes, we demonstrate that mechanical stress-induced apoptosis occurs via the mitochondrial pathway.Our results provide detailed, quantitative insight into the role of micro-environmental mechanical stress in tumor spheroid growth dynamics, and suggest how tumors grow in confined locations where the level of solid stress becomes high. An important implication is that apoptosis via the mitochondrial pathway, induced by compressive stress, may be involved in tumor dormancy, in which tumor growth is held in check by a balance of apoptosis and proliferation.

  9. Principles of the Kenzan Method for Robotic Cell Spheroid-Based Three-Dimensional Bioprinting.

    Science.gov (United States)

    Moldovan, Nicanor I; Hibino, Narutoshi; Nakayama, Koichi

    2017-06-01

    Bioprinting is a technology with the prospect to change the way many diseases are treated, by replacing the damaged tissues with live de novo created biosimilar constructs. However, after more than a decade of incubation and many proofs of concept, the field is still in its infancy. The current stagnation is the consequence of its early success: the first bioprinters, and most of those that followed, were modified versions of the three-dimensional printers used in additive manufacturing, redesigned for layer-by-layer dispersion of biomaterials. In all variants (inkjet, microextrusion, or laser assisted), this approach is material ("scaffold") dependent and energy intensive, making it hardly compatible with some of the intended biological applications. Instead, the future of bioprinting may benefit from the use of gentler scaffold-free bioassembling methods. A substantial body of evidence has accumulated, indicating this is possible by use of preformed cell spheroids, which have been assembled in cartilage, bone, and cardiac muscle-like constructs. However, a commercial instrument capable to directly and precisely "print" spheroids has not been available until the invention of the microneedles-based ("Kenzan") spheroid assembling and the launching in Japan of a bioprinter based on this method. This robotic platform laces spheroids into predesigned contiguous structures with micron-level precision, using stainless steel microneedles ("kenzans") as temporary support. These constructs are further cultivated until the spheroids fuse into cellular aggregates and synthesize their own extracellular matrix, thus attaining the needed structural organization and robustness. This novel technology opens wide opportunities for bioengineering of tissues and organs.

  10. Adult Lung Spheroid Cells Contain Progenitor Cells and Mediate Regeneration in Rodents With Bleomycin-Induced Pulmonary Fibrosis.

    Science.gov (United States)

    Henry, Eric; Cores, Jhon; Hensley, M Taylor; Anthony, Shirena; Vandergriff, Adam; de Andrade, James B M; Allen, Tyler; Caranasos, Thomas G; Lobo, Leonard J; Cheng, Ke

    2015-11-01

    Lung diseases are devastating conditions and ranked as one of the top five causes of mortality worldwide according to the World Health Organization. Stem cell therapy is a promising strategy for lung regeneration. Previous animal and clinical studies have focused on the use of mesenchymal stem cells (from other parts of the body) for lung regenerative therapies. We report a rapid and robust method to generate therapeutic resident lung progenitors from adult lung tissues. Outgrowth cells from healthy lung tissue explants are self-aggregated into three-dimensional lung spheroids in a suspension culture. Without antigenic sorting, the lung spheroids recapitulate the stem cell niche and contain a natural mixture of lung stem cells and supporting cells. In vitro, lung spheroid cells can be expanded to a large quantity and can form alveoli-like structures and acquire mature lung epithelial phenotypes. In severe combined immunodeficiency mice with bleomycin-induced pulmonary fibrosis, intravenous injection of human lung spheroid cells inhibited apoptosis, fibrosis, and infiltration but promoted angiogenesis. In a syngeneic rat model of pulmonary fibrosis, lung spheroid cells outperformed adipose-derived mesenchymal stem cells in reducing fibrotic thickening and infiltration. Previously, lung spheroid cells (the spheroid model) had only been used to study lung cancer cells. Our data suggest that lung spheroids and lung spheroid cells from healthy lung tissues are excellent sources of regenerative lung cells for therapeutic lung regeneration. The results from the present study will lead to future human clinical trials using lung stem cell therapies to treat various incurable lung diseases, including pulmonary fibrosis. The data presented here also provide fundamental knowledge regarding how injected stem cells mediate lung repair in pulmonary fibrosis. ©AlphaMed Press.

  11. SMIFH2-mediated mDia formin functional inhibition potentiates chemotherapeutic targeting of human ovarian cancer spheroids.

    Science.gov (United States)

    Ziske, Megan A; Pettee, Krista M; Khaing, MaNada; Rubinic, Kaitlin; Eisenmann, Kathryn M

    2016-03-25

    Due to a lack of effective screening or prevention protocol for epithelial ovarian cancer (EOC), there is a critical unmet need to develop therapeutic interventions for EOC treatment. EOC metastasis is unique. Initial dissemination is not primarily hematogenous, yet is facilitated through shedding of primary tumor cells into the peritoneal fluid and accumulating ascites. Increasingly, isolated patient spheroids point to a clinical role for spheroids in EOC metastasis. EOC spheroids are highly invasive structures that disseminate upon peritoneal mesothelium, and visceral tissues including liver and omentum. Selection for this subset of chemoresistant EOC cells could influence disease progression and/or recurrence. Thus, targeting spheroid integrity/structure may improve the chemotherapeutic responsiveness of EOC. We discovered a critical role for mammalian Diaphanous (mDia)-related formin-2 in maintaining EOC spheroid structure. Both mDia2 and the related mDia1 regulate F-actin networks critical to maintain cell-cell contacts and the integrity of multi-cellular epithelial sheets. We investigated if mDia2 functional inhibition via a small molecule inhibitor SMIFH2 combined with chemotherapeutics, such as taxol and cisplatin, inhibits the viability of EOC monolayers and clinically relevant spheroids. SMIFH2-mediated mDia formin inhibition significantly reduced both ES2 and Skov3 EOC monolayer viability while spheroid viability was minimally impacted only at the highest concentrations. Combining either cisplatin or taxol with SMIFH2 did not significantly enhance the effects of either drug alone in ES2 monolayers, while Skov3 monolayers treated with taxol or cisplatin and SMIFH2 showed significant additive inhibition of viability. ES2 spheroids were highly responsive with clear additive anti-viability effects with dual taxol or cisplatin when combined with SMIFH2 treatments. While combined taxol with SMIFH2 in spheroids showed an additive effect relative to single

  12. Real-time viability and apoptosis kinetic detection method of 3D multicellular tumor spheroids using the Celigo Image Cytometer.

    Science.gov (United States)

    Kessel, Sarah; Cribbes, Scott; Bonasu, Surekha; Rice, William; Qiu, Jean; Chan, Leo Li-Ying

    2017-09-01

    The development of three-dimensional (3D) multicellular tumor spheroid models for cancer drug discovery research has increased in the recent years. The use of 3D tumor spheroid models may be more representative of the complex in vivo tumor microenvironments in comparison to two-dimensional (2D) assays. Currently, viability of 3D multicellular tumor spheroids has been commonly measured on standard plate-readers using metabolic reagents such as CellTiter-Glo® for end point analysis. Alternatively, high content image cytometers have been used to measure drug effects on spheroid size and viability. Previously, we have demonstrated a novel end point drug screening method for 3D multicellular tumor spheroids using the Celigo Image Cytometer. To better characterize the cancer drug effects, it is important to also measure the kinetic cytotoxic and apoptotic effects on 3D multicellular tumor spheroids. In this work, we demonstrate the use of PI and caspase 3/7 stains to measure viability and apoptosis for 3D multicellular tumor spheroids in real-time. The method was first validated by staining different types of tumor spheroids with PI and caspase 3/7 and monitoring the fluorescent intensities for 16 and 21 days. Next, PI-stained and nonstained control tumor spheroids were digested into single cell suspension to directly measure viability in a 2D assay to determine the potential toxicity of PI. Finally, extensive data analysis was performed on correlating the time-dependent PI and caspase 3/7 fluorescent intensities to the spheroid size and necrotic core formation to determine an optimal starting time point for cancer drug testing. The ability to measure real-time viability and apoptosis is highly important for developing a proper 3D model for screening tumor spheroids, which can allow researchers to determine time-dependent drug effects that usually are not captured by end point assays. This would improve the current tumor spheroid analysis method to potentially better

  13. Wrinkling of Pressurized Elastic Shells

    KAUST Repository

    Vella, Dominic

    2011-10-01

    We study the formation of localized structures formed by the point loading of an internally pressurized elastic shell. While unpressurized shells (such as a ping-pong ball) buckle into polygonal structures, we show that pressurized shells are subject to a wrinkling instability. We study wrinkling in depth, presenting scaling laws for the critical indentation at which wrinkling occurs and the number of wrinkles formed in terms of the internal pressurization and material properties of the shell. These results are validated by numerical simulations. We show that the evolution of the wrinkle length with increasing indentation can be understood for highly pressurized shells from membrane theory. These results suggest that the position and number of wrinkles may be used in combination to give simple methods for the estimation of the mechanical properties of highly pressurized shells. © 2011 American Physical Society.

  14. Seismic analysis of axisymmetric shells

    International Nuclear Information System (INIS)

    Jospin, R.J.; Toledo, E.M.; Feijoo, R.A.

    1984-01-01

    Axisymmetric shells subjected to multiple support excitation are studied. The shells are spatialy discretized by the finite element method and in order to obtain estimates for the maximum values of displacements and stresses the response spectrum tecnique is used. Finally, some numerical results are presented and discussed in the case of a shell of revolution with vertical symmetry axis, subjected to seismic ground motions in the horizontal, vertical and rocking directions. (Author) [pt

  15. Creep analysis of orthotropic shells

    International Nuclear Information System (INIS)

    Mehra, V.K.; Ghosh, A.

    1975-01-01

    A method of creep analysis of orthotropic cylindrical shells subjected to axisymmetric loads has been developed. A general study of creep behaviour of cylindrical shells subjected to a uniform internal pressure has been conducted for a wide range of values of anisotropy coefficients and creep law exponent. Analysis includes determination of stress re-distribution, strain rates, stationary state stresses. Application of reference stress technique has been extended to analysis of shells. (author)

  16. Microscopic description of quadrupole collectivity in neutron-rich nuclei across the N = 126 shell closure

    Science.gov (United States)

    Rodríguez-Guzmán, R.; Robledo, L. M.; Sharma, M. M.

    2015-06-01

    The quadrupole collectivity in Nd, Sm, Gd, Dy, Er, Yb, Hf and W nuclei with neutron numbers 122 ≤ N ≤ 156 is studied, both at the mean field level and beyond, using the Gogny energy density functional. Besides the robustness of the N = 126 neutron shell closure, it is shown that the onset of static deformations in those isotopic chains with increasing neutron number leads to an enhanced stability and further extends the corresponding two-neutron drip lines far beyond what could be expected from spherical calculations. Independence of the mean-field predictions with respect to the particular version of the Gogny energy density functional employed is demonstrated by comparing results based on the D1S and D1M parameter sets. Correlations beyond mean field are taken into account in the framework of the angular momentum projected generator coordinate method calculation. It is shown that N = 126 remains a robust neutron magic number when dynamical effects are included. The analysis of the collective wave functions, average deformations and excitation energies indicate that, with increasing neutron number, the zero-point quantum corrections lead to dominant prolate configurations in the 0{1/+}, 0{2/+}, 2{1/+} and 2{2/+} states of the studied nuclei. Moreover, those dynamical deformation effects provide an enhanced stability that further supports the mean-field predictions, corroborating a shift of the r-process path to higher neutron numbers. Beyond mean-field calculations provide a smaller shell gap at N = 126 than the mean-field one in good agreement with previous theoretical studies. However, the shell gap still remains strong enough in the two-neutron drip lines.

  17. The direct manipulation shell

    International Nuclear Information System (INIS)

    Allen, M.E.; Christiansen, M.

    1992-01-01

    Accelerator controls systems provide parameter display pages which allow the operator to monitor and manipulate selected control points in the system. Display pages are generally implemented as either hand-crafted, purpose-built programs; or by using a specialized display page layout tool. These two methods of display page development exhibit the classic trade-off between functionality vs. ease of implementation. In the Direct Manipulation Shell we approach the process of developing a display page in a manifestly object-oriented manner. This is done by providing a general framework for interactively instantiating and manipulating display objects. (author)

  18. Plate shell structures of glass

    DEFF Research Database (Denmark)

    Bagger, Anne

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

  19. Global gene expression analysis of early response to chemotherapy treatment in ovarian cancer spheroids

    Directory of Open Access Journals (Sweden)

    Tetu Bernard

    2008-02-01

    Full Text Available Abstract Background Chemotherapy (CT resistance in ovarian cancer (OC is broad and encompasses diverse unrelated drugs, suggesting more than one mechanism of resistance. To better understand the molecular mechanisms controlling the immediate response of OC cells to CT exposure, we have performed gene expression profiling in spheroid cultures derived from six OC cell lines (OVCAR3, SKOV3, TOV-112, TOV-21, OV-90 and TOV-155, following treatment with 10,0 μM cisplatin, 2,5 μM paclitaxel or 5,0 μM topotecan for 72 hours. Results Exposure of OC spheroids to these CT drugs resulted in differential expression of genes associated with cell growth and proliferation, cellular assembly and organization, cell death, cell cycle control and cell signaling. Genes, functionally involved in DNA repair, DNA replication and cell cycle arrest were mostly overexpressed, while genes implicated in metabolism (especially lipid metabolism, signal transduction, immune and inflammatory response, transport, transcription regulation and protein biosynthesis, were commonly suppressed following all treatments. Cisplatin and topotecan treatments triggered similar alterations in gene and pathway expression patterns, while paclitaxel action was mainly associated with induction of genes and pathways linked to cellular assembly and organization (including numerous tubulin genes, cell death and protein synthesis. The microarray data were further confirmed by pathway and network analyses. Conclusion Most alterations in gene expression were directly related to mechanisms of the cytotoxics actions in OC spheroids. However, the induction of genes linked to mechanisms of DNA replication and repair in cisplatin- and topotecan-treated OC spheroids could be associated with immediate adaptive response to treatment. Similarly, overexpression of different tubulin genes upon exposure to paclitaxel could represent an early compensatory effect to this drug action. Finally, multicellular

  20. Dossier Shell Eco-Marathon; Dossier Shell Eco-Marathon

    Energy Technology Data Exchange (ETDEWEB)

    Matla, P.

    2012-05-15

    Three articles address subjects concerning the annual race with highly energy efficient cars: the Shell Eco-Marathon. [Dutch] In 3 artikelen wordt aandacht besteed aan de ontwerpen voor de jaarlijkse race met superzuinige auto's, de Shell Eco-Marathon.

  1. Shell model calculations for the A ∼ 100 region: application to the even-Z N = 52 isotones 92Zr -100Cd

    International Nuclear Information System (INIS)

    Halse, P.

    1993-01-01

    Shell model calculations for the Z = 38 - 50 N > 50 region, with a space of protons in the 2p 1/2 , 1g 9/2 orbits and neutrons in the 2d 5/2 , 3s 1/2 , 2d 3/2 , 1g 7/2 orbits, are initiated by the selection of a schematic Hamiltonian and effective electromagnetic operators. An application to the Z-even N = 52 isotones gives a good description for energies of both low-spin and yrast high-spin levels, and for E2 and M1 transition strengths and moments where these have been measured, over the entire range of Z. The calculated E2 matrix elements for the lower-spin yrast states in 98 Pd and 100 Cd suggest a finite and stable prolate deformation with β ∼ 0.1, in marked contrast to previous collective interpretations. 28 refs., 4 tabs., 4 figs

  2. Study of the effect of vitamins C and E on the radiation response of multicell spheroids treated with Adriamycin

    International Nuclear Information System (INIS)

    Sridhar, R.; Stroude, E.; Inch, W.R.

    1979-01-01

    Treatment with Adriamycin (0.6 μg/ml for 60 min) was not cytotoxic to multicell spheroids. At this concentration, the drug was not a sensitizer of hypoxic cells in V79 multicell spheroids, which were irradiated at 37 0 C in medium equilibrated with a mixture of 5% O 2 :3% CO 2 :92% N 2 . The addition of vitamins C and E did not increase the radiation sensitivity of Adriamycin-treated spheroids. In some experiments, catalase was included in the growth medium to overcome the toxic effect of hydrogen peroxide, which is known to be formed in solutions containing vitamin C and also in Adriamycin solutions treated with vitamin C or microsomal preparations. As a result of these experiments, it was found that catalase increased the radiation killing in multicell spheroids

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

    International Nuclear Information System (INIS)

    Heiles, C.

    1984-01-01

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

  4. Optimization of the formation of embedded multicellular spheroids of MCF-7 cells: How to reliably produce a biomimetic 3D model.

    Science.gov (United States)

    Zhang, Wenli; Li, Caibin; Baguley, Bruce C; Zhou, Fang; Zhou, Weisai; Shaw, John P; Wang, Zhen; Wu, Zimei; Liu, Jianping

    2016-12-15

    To obtain a multicellular MCF-7 spheroid model to mimic the three-dimensional (3D) of tumors, the microwell liquid overlay (A) and hanging-drop/agar (B) methods were first compared for their technical parameters. Then a method for embedding spheroids within collagen was optimized. For method A, centrifugation assisted cells form irregular aggregates but not spheroids. For method B, an extended sedimentation period of over 24 h for cell suspensions and increased viscosity of the culture medium using methylcellulose were necessary to harvest a dense and regular cell spheroid. When the number was less than 5000 cells/drop, embedded spheroids showed no tight cores and higher viability than the unembedded. However, above 5000 cells/drop, cellular viability of embedded spheroids was not significantly different from unembedded spheroids and cells invading through the collagen were in a sun-burst pattern with tight cores. Propidium Iodide staining indicated that spheroids had necrotic cores. The doxorubicin cytotoxicity demonstrated that spheroids were less susceptible to DOX than their monolayer cells. A reliable and reproducible method for embedding spheroids using the hanging-drop/agarose method within collagen is described herein. The cell culture model can be used to guide experimental manipulation of 3D cell cultures and to evaluate anticancer drug efficacy. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. Solving ground eigenvalue and eigenfunction of spheroidal wave equation at low frequency by supersymmetric quantum mechanics method

    Institute of Scientific and Technical Information of China (English)

    Tang Wen-Lin; Tian Gui-Hua

    2011-01-01

    The spheroidal wave functions are found to have extensive applications in many branches of physics and mathematics. We use the perturbation method in supersymmetric quantum mechanics to obtain the analytic ground eigenvalue and the ground eigenfunction of the angular spheroidal wave equation at low frequency in a series form. Using this approach, the numerical determinations of the ground eigenvalue and the ground eigenfunction for small complex frequencies are also obtained.

  6. Expansion of a zero-order Bessel beam in spheroidal coordinates by generalized Lorenz–Mie theory

    International Nuclear Information System (INIS)

    Han, L.; Han, Y.P.; Cui, Z.W.; Wang, J.J.

    2014-01-01

    An analytic solution to the scattering of the zero-order Bessel beam by a spheroidal particle is constructed on the basis of the generalized Lorenz–Mie theory (GLMT). The spheroidal beam shape coefficients (BSCs) of the zero-order Bessel beam are directly expressed in spheroidal coordinates and computed conveniently using an intrinsic method. Utilizing the tangential continuity of the electromagnetic fields, the expression coefficients of scattered and internal fields are determined. Numerical results concerning scattered field in the far zone are displayed for various parameters of the incident electromagnetic beam and of the scatter. These results are expected to provide useful insights into the scattering of a Bessel beam by spheroidal particles and particle manipulation applications using Bessel beams. - Highlights: • The scattering of zero-order Bessel beam by dielectric spheroid is investigated. • The analytic solution is constructed within the framework of the GLMT. • The spheroidal beam shape coefficients of the zero-order Bessel beam are computed by use an intrinsic method. • Numerical results concerning scattered field are displayed for various parameters

  7. Investigating the spectral characteristics of backscattering from heterogeneous spheroidal nuclei using broadband finite-difference time-domain simulations

    Science.gov (United States)

    Chao, Guo-Shan; Sung, Kung-Bin

    2010-02-01

    Backscattered light spectra have been used to extract size distribution of cell nuclei in epithelial tissues for noninvasive detection of precancerous lesions. In existing experimental studies, size estimation is achieved by assuming nuclei as homogeneous spheres or spheroids and fitting the measured data with models based on Mie theory. However, the validity of simplifying nuclei as homogeneous spheres has not been thoroughly examined. In this study, we investigate the spectral characteristics of backscattering from models of spheroidal nuclei under plane wave illumination using three-dimensional finite-difference time-domain (FDTD) simulation. A modulated Gaussian pulse is used to obtain wavelength dependent scattering intensity with a single FDTD run. The simulated model of nuclei consists of a nucleolus and randomly distributed chromatin condensation in homogeneous cytoplasm and nucleoplasm. The results show that backscattering spectra from spheroidal nuclei have similar oscillating patterns to those from homogeneous spheres with the diameter equal to the projective length of the spheroidal nucleus along the propagation direction. The strength of backscattering is enhanced in heterogeneous spheroids as compared to homogeneous spheroids. The degree of which backscattering spectra of heterogeneous nuclei deviate from Mie theory is highly dependent on the distribution of chromatin/nucleolus but not sensitive to nucleolar size, refractive index fluctuation or chromatin density.

  8. Imaging- and Flow Cytometry-based Analysis of Cell Position and the Cell Cycle in 3D Melanoma Spheroids

    Science.gov (United States)

    Beaumont, Kimberley A.; Anfosso, Andrea; Ahmed, Farzana

    2015-01-01

    Three-dimensional (3D) tumor spheroids are utilized in cancer research as a more accurate model of the in vivo tumor microenvironment, compared to traditional two-dimensional (2D) cell culture. The spheroid model is able to mimic the effects of cell-cell interaction, hypoxia and nutrient deprivation, and drug penetration. One characteristic of this model is the development of a necrotic core, surrounded by a ring of G1 arrested cells, with proliferating cells on the outer layers of the spheroid. Of interest in the cancer field is how different regions of the spheroid respond to drug therapies as well as genetic or environmental manipulation. We describe here the use of the fluorescence ubiquitination cell cycle indicator (FUCCI) system along with cytometry and image analysis using commercial software to characterize the cell cycle status of cells with respect to their position inside melanoma spheroids. These methods may be used to track changes in cell cycle status, gene/protein expression or cell viability in different sub-regions of tumor spheroids over time and under different conditions. PMID:26779761

  9. Shell Trumpets from Western Mexico

    Directory of Open Access Journals (Sweden)

    Robert Novella

    1991-11-01

    Full Text Available Marine shells have been used as musical instruments in almost all parts of the world (Izikowitz 1935, including Mesoamerica, where large univalves, also called conch shells in the literature, had a utilitarian function as trumpets. Their use is well documented in most cultural areas of Mesoamerica, as in Western Mexico, through their various occurrences in archaeological contexts and museums collections.

  10. Cylindrical thin-shell wormholes

    International Nuclear Information System (INIS)

    Eiroa, Ernesto F.; Simeone, Claudio

    2004-01-01

    A general formalism for the dynamics of nonrotating cylindrical thin-shell wormholes is developed. The time evolution of the throat is explicitly obtained for thin-shell wormholes whose metric has the form associated with local cosmic strings. It is found that the throat collapses to zero radius, remains static, or expands forever, depending only on the sign of its initial velocity

  11. Shell model and spectroscopic factors

    International Nuclear Information System (INIS)

    Poves, P.

    2007-01-01

    In these lectures, I introduce the notion of spectroscopic factor in the shell model context. A brief review is given of the present status of the large scale applications of the Interacting Shell Model. The spectroscopic factors and the spectroscopic strength are discussed for nuclei in the vicinity of magic closures and for deformed nuclei. (author)

  12. Conventional shell model: some issues

    International Nuclear Information System (INIS)

    Vallieres, M.; Pan, X.W.; Feng, D.H.; Novoselsky, A.

    1997-01-01

    We discuss some important issues in shell-model calculations related to the effective interactions used in different regions of the periodic table; in particular the quality of different interactions is discussed, as well as the mass dependence of the interactions. Mention is made of the recently developed Drexel University shell-model (DUSM). (orig.)

  13. Expert system development (ESD) shell

    International Nuclear Information System (INIS)

    Padmini, S.; Diwakar, M.P.; Rathode, N.C.; Bairi, B.R.

    1991-01-01

    An Expert System Development (ESD) Shell design implementation is desribed in detail. The shell provides high-level generic facilities for Knowledge Representation (KR) and inferencing and tools for developing user interfaces. Powerful set of tools in the shell relieves much of the programming burden in the ES development. The shell is written in PROLOG under IBM PC/AT. KR facilities are based on two very powerful formalisms namely, frames and rules. Inference Engine (IE) draws most of its power from unification and backward reasoning strategy in PROLOG. This basic mechanism is enhanced further by incorporating both forward and backward chaining of rules and frame-based inferencing. Overall programming style integrates multiple paradigms including logic, object oriented, access-oriented and imperative programming. This permits ES designer a lot of flexibility in organizing inference control. Creation and maintainance of knowledge base is a major activity. The shell, therefore, provides number of facilities to simplify these tasks. Shell design also takes note of the fact that final success of any system depends on end-user satisfaction and hence provides features to build use-friendly interfaces. The shell also provides a set of interfacing predicates so that it can be embedded within any PROLOG program to incorporate functionalilty of the shell in the user program. (author). 10 refs., 8 figs

  14. Cell-free DNA in a three-dimensional spheroid cell culture model

    DEFF Research Database (Denmark)

    Aucamp, Janine; Calitz, Carlemi; Bronkhorst, Abel J.

    2017-01-01

    Background Investigating the biological functions of cell-free DNA (cfDNA) is limited by the interference of vast numbers of putative sources and causes of DNA release into circulation. Utilization of three-dimensional (3D) spheroid cell cultures, models with characteristics closer to the in vivo...... cultures can serve as effective, simplified in vivo-simulating “closed-circuit” models since putative sources of cfDNA are limited to only the targeted cells. In addition, cfDNA can also serve as an alternative or auxiliary marker for tracking spheroid growth, development and culture stability. Biological...... significance 3D cell cultures can be used to translate “closed-circuit” in vitro model research into data that is relevant for in vivo studies and clinical applications. In turn, the utilization of cfDNA during 3D culture research can optimize sample collection without affecting the stability of the growth...

  15. On the role of the transformation eigenstrain in the growth or shrinkage of spheroidal isotropic precipitations

    International Nuclear Information System (INIS)

    Fischer, F.D.; Boehm, H.J.

    2005-01-01

    The jumps of the strain and stress tensors on the surface of elastic homogeneous or inhomogeneous ellipsoidal inclusions embedded in an elastic matrix are obtained from results reported in the literature. They are used to derive closed-form expressions for the thermodynamic force in such matrix-inclusion systems that are subjected to a generally defined homogeneous transformation eigenstrain. A detailed study is presented for an isotropic spheroidal inclusion in an isotropic matrix in which the most important parameters are the inclusion's aspect ratio α and an eigenstrain triaxiality parameter d-bar. The fluctuations of the thermodynamic force are investigated for a set of specific transformation eigenstrain tensors and are presented for inclusion shapes ranging from disk-like to fiber-like spheroids

  16. Gravitational collision efficiency of nonspherical aerosols II: motion of an oblate spheroid in a viscous fluid

    Energy Technology Data Exchange (ETDEWEB)

    Tuttle, R.F.; Loyalka, S.K.

    1985-06-01

    The collisional dynamics of nonspherical aerosols is modeled by the introduction of a shape factor, US . Mechanistic calculation of US requires knowledge of the flow fields around the aerosols. Since actual aerosols can be complicated in shape and since the computation of flow fields can be quite difficult, insights into the nature of US are gained by using the superposition technique and studying aerosols that have tractable flow fields. The motion of an oblate spheroid in a viscous fluid is considered. The Navier-Stokes equations and associated boundary conditions are represented in oblate spheroidal coordinates. A combination of finite differences and spline-interpolation techniques is used to transform these equations to a form suitable for numerical computations. Converged results for the flow fields are obtained for a 0 to 5 range of Reynolds numbers. In the limit of zero Reynolds number, the results are found to be in agreement with the analytical solutions of Oberbeck.

  17. Angular velocity of a spheroid log rolling in a simple shear at small Reynolds number

    Science.gov (United States)

    Meibohm, Jan; Candelier, Fabien; Rosen, Tomas; Einarsson, Jonas; Lundell, Fredrik; Mehlig, Bernhard

    2016-11-01

    We analyse the angular velocity of a small neutrally buoyant spheroid log rolling in a simple shear. When the effect of fluid inertia is negligible the angular velocity ω -> equals half the fluid vorticity. We compute by singular perturbation theory how weak fluid inertia reduces the angular velocity in an unbounded shear, and how this reduction depends upon the shape of the spheroid (on its aspect ratio). In addition we determine the angular velocity by direct numerical simulations. The results are in excellent agreement with the theory at small but not too small values of the shear Reynolds number, for all aspect ratios considered. For the special case of a sphere we find ω / s = - 1 / 2 + 0 . 0540Re 3 / 2 where s is the shear rate and Re is the shear Reynolds number. This result differs from that derived by Lin et al. who obtained a numerical coefficient roughly three times larger.

  18. Suspected Perinatal Depression Revealed to be Hereditary Diffuse Leukoencephalopathy with Spheroids.

    Science.gov (United States)

    Blume, Josefine; Weissert, Robert

    2017-01-01

    Early motor symptoms of neurodegenerative diseases often appear in combination with psychiatric symptoms, such as depression or personality changes, and are in danger of being misdiagnosed as psychogenic in young patients. We present the case of a 32-year-old woman who presented with rapid-onset depression, followed by a hypokinetic movement disorder and cognitive decline during pregnancy. Genetic testing revealed a mutation in the colony-stimulating factor 1 receptor gene, which led to the diagnosis of hereditary diffuse leukoencephalopathy with spheroids. Hereditary diffuse leukoencephalopathy with spheroids (HDLS) is probably an under-recognized disease. HDLS should be considered in patients with rapidly progressing parkinsonian symptoms and dementia accompanied by white matter lesions.

  19. Suspected Perinatal Depression Revealed to be Hereditary Diffuse Leukoencephalopathy with Spheroids

    Directory of Open Access Journals (Sweden)

    Josefine Blume

    2017-01-01

    Full Text Available Early motor symptoms of neurodegenerative diseases often appear in combination with psychiatric symptoms, such as depression or personality changes, and are in danger of being misdiagnosed as psychogenic in young patients. We present the case of a 32-year-old woman who presented with rapid-onset depression, followed by a hypokinetic movement disorder and cognitive decline during pregnancy. Genetic testing revealed a mutation in the colony-stimulating factor 1 receptor gene, which led to the diagnosis of hereditary diffuse leukoencephalopathy with spheroids. Hereditary diffuse leukoencephalopathy with spheroids (HDLS is probably an under-recognized disease. HDLS should be considered in patients with rapidly progressing parkinsonian symptoms and dementia accompanied by white matter lesions.

  20. Generation of uniform magnetic field using a spheroidal helical coil structure

    International Nuclear Information System (INIS)

    Öztürk, Yavuz; Aktaş, Bekir

    2016-01-01

    Uniformity of magnetic fields are of great importance especially in magnetic resonance studies, namely in magnetic resonance spectroscopy applications (NMR, FMR, ESR, EPR etc.) and magnetic resonance imaging applications (MRI, FMRI). Field uniformity is also required in some other applications such as eddy current probes, magnetometers, magnetic traps, particle counters etc. Here we proposed a coil winding regime, which follows the surface of a spheroid (an ellipsoid of rotation); in light of previous theoretical studies suggesting perfect uniformity for a constant ampere per turn in the axial direction thereof. We demonstrated our theoretical results from finite element calculations suggesting 0.15% of field uniformity for the proposed structure, which we called a Spheroidal Helical Coil. (paper)

  1. Dielectric tensor elements for the description of waves in rotating inhomogeneous magnetized plasma spheroids

    Science.gov (United States)

    Abdoli-Arani, A.; Ramezani-Arani, R.

    2012-11-01

    The dielectric permittivity tensor elements of a rotating cold collisionless plasma spheroid in an external magnetic field with toroidal and axial components are obtained. The effects of inhomogeneity in the densities of charged particles and the initial toroidal velocity on the dielectric permittivity tensor and field equations are investigated. The field components in terms of their toroidal components are calculated and it is shown that the toroidal components of the electric and magnetic fields are coupled by two differential equations. The influence of thermal and collisional effects on the dielectric tensor and field equations in the rotating plasma spheroid are also investigated. In the limiting spherical case, the dielectric tensor of a stationary magnetized collisionless cold plasma sphere is presented.

  2. Simulation study of spheroidal dust gains charging: Applicable to dust grain alignment

    International Nuclear Information System (INIS)

    Zahed, H.; Sobhanian, S.; Mahmoodi, J.; Khorram, S.

    2006-01-01

    The charging process of nonspherical dust grains in an unmagnetized plasma as well as in the presence of a magnetic field is studied. It is shown that unlike the spherical dust grain, due to nonhomogeneity of charge distribution on the spheroidal dust surface, the resultant electric forces on electrons and ions are different. This process produces some surface charge density gradient on the nonspherical grain surface. Effects of a magnetic field and other plasma parameters on the properties of the dust particulate are studied. It has been shown that the alignment direction could be changed or even reversed with the magnetic field and plasma parameters. Finally, the charge distribution on the spheroidal grain surface is studied for different ambient parameters including plasma temperature, neutral collision frequency, and the magnitude of the magnetic field

  3. Confinement of nonneutral spheroidal plasmas in multi-ring electrode traps

    International Nuclear Information System (INIS)

    Mohri, Akihiro; Yuyama, Tetsumori; Michishita, Toshinori; Higaki, Hiroyuki; Tanaka, Hitoshi; Yamazawa, Yohei; Aoyagi, Masayuki

    1998-01-01

    A nonneutral spheroidal plasma can be settled in a rigid rotor equilibrium inside a closed conducting cell independently of induced image charges on the cell wall if the electrostatic potential distribution on the wall surface is set equal to the sum of the external hyperbolic potential (r 2 -2z 2 ) and the self-potential produced by the plasma. A confinement system equipped with a train of properly biased ring electrodes can approximately generate any axisymmetric potential, including the above field. Experiments on confinement of electron spheroids in such a system showed that the confinement time became the longest when the condition to diminish the image charge effects was satisfied. The observed frequency of the centre-of-mass harmonic oscillation of the plasma in this configuration was in good agreement with the estimated one. (author)

  4. Anodic Dissolution of Spheroidal Graphite Cast Iron with Different Pearlite Areas in Sulfuric Acid Solutions

    Directory of Open Access Journals (Sweden)

    Yoshikazu Miyata

    2013-01-01

    Full Text Available The rate equation of anodic dissolution reaction of spheroidal graphite cast iron in sulfuric acid solutions at 298 K has been studied. The cast irons have different areas of pearlite. The anodic Tafel slope of 0.043 V decade−1 and the reaction order with respect to the hydroxyl ion activity of 1 are obtained by the linear potential sweep technique. The anodic current density does not depend on the area of pearlite. There is no difference in the anodic dissolution reaction mechanisms between pure iron and spheroidal graphite cast iron. The anodic current density of the cast iron is higher than that of the pure iron.

  5. Radiation-biological investigations with multicellular spheroids as an in vitro tumour model. 2

    International Nuclear Information System (INIS)

    Koerner, I.J.; Kopp, J.; Malz, W.

    1978-01-01

    Using the alkaline sucrose gradient sedimentation technique, the single-strand break rejoining in single cells and cells of small sheroids was studied after X-irradiation with 10 krads. The half life time for the fast rejoining process amounts to about 4 minutes for single cells and to about 1.5 minutes for small spheroids. While in single cells 7 per cent of single-strand breaks remain unrepaired after 80 minutes incubation at 37 0 C, in small spheroids practically no residual unrepaired single-strand breaks can be detected after more than 20 minutes. The corresponding survival of cells of small sheroids is increased in comparison with single cells. Possible reasons are discussed for the different repair capacities found. (author)

  6. Measurement uncertainty evaluation of cellular spheroids surface tension in compressing tests using Young-Laplace equation

    Science.gov (United States)

    Beatrici, Anderson; Santos Baptista, Leandra; Mauro Granjeiro, José

    2018-03-01

    Regenerative Medicine comprises the Biotechnology, Tissue Engineering and Biometrology for stem cell therapy. Starting from stem cells extracted from the patient, autologous implant, these cells are cultured and differentiated into other tissues, for example, articular cartilage. These cells are reorganized into microspheres (cell spheroids). Such tissue units are recombined into functional tissues constructs that can be implanted in the injured region for regeneration. It is necessary the biomechanical characterization of these constructed to determine if their properties are similar to native tissue. In this study was carried out the modeling of the calculation of uncertainty of the surface tension of cellular spheroids with the use of the Young-Laplace equation. We obtained relative uncertainties about 10%.

  7. A comparative study of post-irradiation growth kinetics of spheroids and monolayers

    International Nuclear Information System (INIS)

    Dertinger, J.; Luecke-Huhle, C.

    1975-01-01

    Post-irradiation growth kinetics of γ-irradiated spheroid and monolayer cells in exponential growth phase was investigated by means of dose-response curves based on cell counts after specified time intervals following irradiation. A mathematical model of cell-growth after irradiation was fitted to these curves. The model parameters (related to division delay and growth of non-surviving cells) obtained from this analysis consistently indicated increasing resistance to sub-lethal damage of cells cultured as multicellular spheroids under conditions of increasing three-dimensional contact. In contrast, no indication of an increased radiation-resistance was found with cells cultured on a substratum under a variety of conditions. (author)

  8. Curcumin-loaded chitosan-cholesterol micelles: evaluation in monolayers and 3D cancer spheroid model.

    Science.gov (United States)

    Muddineti, Omkara Swami; Kumari, Preeti; Ray, Eupa; Ghosh, Balaram; Biswas, Swati

    2017-06-02

    To improve the bioavailability and anticancer potential of curcumin by using a cholesterol-conjugated chitosan micelle. Methods & methods: Cholesterol was conjugated to chitosan (15 kDa) to form self-assembled micelles, which loaded curcumin. Physicochemical characterization and formulation optimization of the drug-loaded micelles (curcumin-loaded chitosan-cholesterol micelles [C-CCM]) were performed. In vitro cellular uptake and viability of C-CCM were investigated in melanoma and breast cancer cell lines. The antitumor efficacy was evaluated in 3D lung cancer spheroid model. The optimized C-CCM had size of approximately 162 nm with loading efficiency of approximately 36%. C-CCM was taken up efficiently by the cells, and it reduced cancer cell viability significantly compared with free curcumin. C-CCM enhanced the antitumor efficacy in spheroids, suggesting that C-CCM could be used as an effective chemotherapy in cancer.

  9. Structural Transition in a Fluid of Spheroids: A Low-Density Vestige of Jamming.

    Science.gov (United States)

    Cohen, A P; Dorosz, S; Schofield, A B; Schilling, T; Sloutskin, E

    2016-03-04

    A thermodynamically equilibrated fluid of hard spheroids is a simple model of liquid matter. In this model, the coupling between the rotational degrees of freedom of the constituent particles and their translations may be switched off by a continuous deformation of a spheroid of aspect ratio t into a sphere (t=1). We demonstrate, by experiments, theory, and computer simulations, that dramatic nonanalytic changes in structure and thermodynamics of the fluids take place, as the coupling between rotations and translations is made to vanish. This nonanalyticity, reminiscent of a second-order liquid-liquid phase transition, is not a trivial consequence of the shape of an individual particle. Rather, free volume considerations relate the observed transition to a similar nonanalyticity at t=1 in structural properties of jammed granular ellipsoids. This observation suggests a deep connection to exist between the physics of jamming and the thermodynamics of simple fluids.

  10. Dynamic centering of liquid shells

    International Nuclear Information System (INIS)

    Tsamopoulos, J.A.; Brown, R.A.

    1987-01-01

    The moderate-amplitude axisymmetric oscillations of an inviscid liquid shell surrounding an incompressible gas bubble are calculated by a multiple-time-scale expansion for initial deformations composed of two-lobed perturbations of the shell and a displacement of the bubble from the center of mass of the liquid. Two types of small-amplitude motion are identified and lead to very different nonlinear dynamic interactions, as described by the results valid up to second order in the amplitude of the initial deformation. In the ''bubble mode,'' the oscillations of the captive bubble and the liquid shell are exactly in phase and the bubble vibrates about its initial eccentric location. The bubble moves toward the center of the drop when the shell is perturbed into a ''sloshing mode'' of oscillation where both interfaces move out of phase. These results explain the centering of liquid shells observed in several experiments

  11. Miniaturized microscope for high throughput screening of tumor spheroids in microfluidic devices

    Science.gov (United States)

    Uranga, Javier; Rodríguez-Pena, Alejandro; Gahigiro, Desiré; Ortiz-de-Solorzano, Carlos

    2018-02-01

    High-throughput in vitro screening of highly physiological three-dimensional cell cultures (3D-HTS) is rapidly gaining importance in preclinical studies, to study the effect of the microenvironment in tumor development, and to evaluate the efficacy of new anticancer drugs. Furthermore, it could also be envisioned the use of 3D-HTS systems in personalized anti-cancer treatment planning, based on tumor organoids or spheroids grown from tumor biopsies or isolated tumor circulating cells. Most commercial, multi-well plate based 3D-HTS systems are large, expensive, and are based on the use of multi-well plates that hardly provide a physiological environment and require the use of large amounts of biological material and reagents. In this paper we present a novel, miniaturized inverted microscope (hereinafter miniscospe), made up of low-cost, mass producible parts, that can be used to monitor the growth of living tumor cell spheroids within customized three-dimensional microfluidic platforms. Our 3D-HTS miniscope combines phase contrast imaging based on oblique back illumination technique with traditional widefield epi-fluorescence imaging, implemented using miniaturized electro-optical parts and gradient-index refraction lenses. This small (3x6x2cm), lightweight device can effectively image overtime the growth of (>200) tumor spheroids in a controlled and reproducible environment. Our miniscope can be used to acquire time-lapse images of cellular living spheroids over the course of several hours and captures their growth before and after drug treatment, to evaluate the effectiveness of the drug.

  12. Chemical composition of extremely metal-poor stars in the Sextans dwarf spheroidal galaxy

    OpenAIRE

    Aoki, W.; Arimoto, N.; Sadakane, K.; Tolstoy, E.; Battaglia, G.; Jablonka, P.; Shetrone, M.; Letarte, B.; Irwin, M.; Hill, V.; Francois, P.; Venn, K.; Primas, F.; Helmi, A.; Kaufer, A.

    2009-01-01

    Context. Individual stars in dwarf spheroidal galaxies around the Milky Way Galaxy have been studied both photometrically and spectroscopically. Extremely metal-poor stars among them are very valuable because they should record the early enrichment in the Local Group. However, our understanding of these stars is very limited because detailed chemical abundance measurements are needed from high resolution spectroscopy. Aims. To constrain the formation and chemical evolution of dwarf galaxi...

  13. Model-independent constraints on dark matter annihilation in dwarf spheroidal galaxies

    OpenAIRE

    Boddy, Kimberly K.; Kumar, Jason; Marfatia, Danny; Sandick, Pearl

    2018-01-01

    We present a general, model-independent formalism for determining bounds on the production of photons in dwarf spheroidal galaxies via dark matter annihilation, applicable to any set of assumptions about dark matter particle physics or astrophysics. As an illustration, we analyze gamma-ray data from the Fermi Large Area Telescope to constrain a variety of nonstandard dark matter models, several of which have not previously been studied in the context of dwarf galaxy searches.

  14. Wearing Quality of Austenitic, Duplex Cast Steel, Gray and Spheroidal Graphite Iron

    Directory of Open Access Journals (Sweden)

    S. Pietrowski

    2012-04-01

    Full Text Available The current work presents the research results of abrasion wear and adhesive wear at rubbing and liquid friction of new austenitic, austenitic-ferritic (“duplex” cast steel and gray cast iron EN-GJL-250, spheroidal graphite iron EN-GJS-600-3, pearlitic with ledeburitic carbides and spheroidal graphite iron with ledeburitic carbides with a microstructure of the metal matrix: pearlitic, upper bainite, mixture of upper and lower bainite, martensitic with austenite, pearlitic-martensitic-bainitic-ausferritic obtained in the raw state. The wearing quality test was carried out on a specially designed and made bench. Resistance to abrasion wear was tested using sand paper P40. Resistance to adhesive wear was tested in interaction with steel C55 normalized, hardened and sulfonitrided. The liquid friction was obtained using CASTROL oil. It was stated that austenitic cast steel and “duplex” are characterized by a similar value of abrasion wear and adhesive wear at rubbing friction. The smallest decrease in mass was shown by the cast steel in interaction with the sulfonitrided steel C55. Austenitic cast steel and “duplex��� in different combinations of friction pairs have a higher wear quality than gray cast iron EN-GJL- 250 and spheroidal graphite iron EN-GJS-600-3. Austenitic cast steel and “duplex” are characterized by a lower wearing quality than the spheroidal graphite iron with bainitic-martensitic microstructure. In the adhesive wear test using CASTROL oil the tested cast steels and cast irons showed a small mass decrease within the range of 1÷2 mg.

  15. Spheroidal and conical shapes of ferrofluid-filled capsules in magnetic fields

    Science.gov (United States)

    Wischnewski, Christian; Kierfeld, Jan

    2018-04-01

    We investigate the deformation of soft spherical elastic capsules filled with a ferrofluid in external uniform magnetic fields at fixed volume by a combination of numerical and analytical approaches. We develop a numerical iterative solution strategy based on nonlinear elastic shape equations to calculate the stretched capsule shape numerically and a coupled finite element and boundary element method to solve the corresponding magnetostatic problem and employ analytical linear response theory, approximative energy minimization, and slender-body theory. The observed deformation behavior is qualitatively similar to the deformation of ferrofluid droplets in uniform magnetic fields. Homogeneous magnetic fields elongate the capsule and a discontinuous shape transition from a spheroidal shape to a conical shape takes place at a critical field strength. We investigate how capsule elasticity modifies this hysteretic shape transition. We show that conical capsule shapes are possible but involve diverging stretch factors at the tips, which gives rise to rupture for real capsule materials. In a slender-body approximation we find that the critical susceptibility above which conical shapes occur for ferrofluid capsules is the same as for droplets. At small fields capsules remain spheroidal and we characterize the deformation of spheroidal capsules both analytically and numerically. Finally, we determine whether wrinkling of a spheroidal capsule occurs during elongation in a magnetic field and how it modifies the stretching behavior. We find the nontrivial dependence between the extent of the wrinkled region and capsule elongation. Our results can be helpful in quantitatively determining capsule or ferrofluid material properties from magnetic deformation experiments. All results also apply to elastic capsules filled with a dielectric liquid in an external uniform electric field.

  16. Energy metabolism and biotransformation as endpoints to pre-screen hepatotoxicity using a liver spheroid model

    International Nuclear Information System (INIS)

    Xu Jinsheng; Purcell, Wendy M.

    2006-01-01

    The current study investigated liver spheroid culture as an in vitro model to evaluate the endpoints relevant to the status of energy metabolism and biotransformation after exposure to test toxicants. Mature rat liver spheroids were exposed to diclofenac, galactosamine, isoniazid, paracetamol, m-dinitrobenzene (m-DNB) and 3-nitroaniline (3-NA) for 24 h. Pyruvate uptake, galactose biotransformation, lactate release and glucose secretion were evaluated after exposure. The results showed that pyruvate uptake and lactate release by mature liver spheroids in culture were maintained at a relatively stable level. These endpoints, together with glucose secretion and galactose biotransformation, were related to and could reflect the status of energy metabolism and biotransformation in hepatocytes. After exposure, all of the test agents significantly reduced glucose secretion, which was shown to be the most sensitive endpoint of those evaluated. Diclofenac, isoniazid, paracetamol and galactosamine reduced lactate release (P < 0.01), but m-DNB increased lactate release (P < 0.01). Diclofenac, isoniazid and paracetamol also reduced pyruvate uptake (P < 0.01), while galactosamine had little discernible effect. Diclofenac, galactosamine, paracetamol and m-DNB also reduced galactose biotransformation (P < 0.01), by contrast, isoniazid did not. The metabolite of m-DNB, 3-NA, which served as a negative control, did not cause significant changes in lactate release, pyruvate uptake or galactose biotransformation. It is concluded that pyruvate uptake, galactose biotransformation, lactate release and glucose secretion can be used as endpoints for evaluating the status of energy metabolism and biotransformation after exposure to test agents using the liver spheroid model to pre-screen hepatotoxicity

  17. Theory of axially symmetric probes in a collisionless magnetoplasma: Aligned spheroids, finite cylinders, and disks

    International Nuclear Information System (INIS)

    Rubinstein, J.; Laframboise, J.G.

    1983-01-01

    A theory is presented for current collection by electrostatic probes in a collisionless, Maxwellian plasma containing a uniform magnetic field B, where the probes are spheroids or finite cylinders whose axis of symmetry is aligned with B, or disks perpendicular to B. The theory yields upper-bound and adiabatic-limit currents for the attracted particle species. For the repelled species, it yields upper and lower bounds. This work is an extension of existing theory for spherical probes by Rubinstein and Laframboise

  18. Numerical Simulation of Spheroidization Process of TiAl Alloy Powders in Radio Frequency Plasma

    OpenAIRE

    ZHU Langping; LU Xin; LIU Chengcheng; LI Jianchong; NAN Hai

    2017-01-01

    A numerical simulation method was used to study the radio frequency plasma spheroidization process of TiAl alloy powder. The effects of velocity field and temperature field on the motion trajectory and mass change of TiAl alloy powder with different particle size were analyzed.The results show that the temperature of powder particles increases rapidly under high temperature plasma, surface evaporation cause the reduction of particle size, and particles with small size tend to evaporate quickl...

  19. A 3D printed microfluidic perfusion device for multicellular spheroid cultures.

    Science.gov (United States)

    Ong, Louis Jun Ye; Islam, Anik; DasGupta, Ramanuj; Iyer, Narayanan Gopalakkrishna; Leo, Hwa Liang; Toh, Yi-Chin

    2017-09-11

    The advent of 3D printing technologies promises to make microfluidic organ-on-chip technologies more accessible for the biological research community. To date, hydrogel-encapsulated cells have been successfully incorporated into 3D printed microfluidic devices. However, there is currently no 3D printed microfluidic device that can support multicellular spheroid culture, which facilitates extensive cell-cell contacts important for recapitulating many multicellular functional biological structures. Here, we report a first instance of fabricating a 3D printed microfluidic cell culture device capable of directly immobilizing and maintaining the viability and functionality of 3D multicellular spheroids. We evaluated the feasibility of two common 3D printing technologies i.e. stereolithography (SLA) and PolyJet printing, and found that SLA could prototype a device comprising of cell immobilizing micro-structures that were housed within a microfluidic network with higher fidelity. We have also implemented a pump-free perfusion system, relying on gravity-driven flow to perform medium perfusion in order to reduce the complexity and footprint of the device setup, thereby improving its adaptability into a standard biological laboratory. Finally, we demonstrated the biological performance of the 3D printed device by performing pump-free perfusion cultures of patient-derived parental and metastatic oral squamous cell carcinoma tumor and liver cell (HepG2) spheroids with good cell viability and functionality. This paper presents a proof-of-concept in simplifying and integrating the prototyping and operation of a microfluidic spheroid culture device, which will facilitate its applications in various drug efficacy, metabolism and toxicity studies.

  20. Hydrolysis of phosphatidylcholine by hepatic lipase in discoidal and spheroidal recombinant high-density lipoprotein.

    Science.gov (United States)

    Tansey, J T; Thuren, T Y; Jerome, W G; Hantgan, R R; Grant, K; Waite, M

    1997-10-07

    Hepatic lipase (HL) hydrolysis of phosphatidylcholine (PC) was studied in recombinant high-density lipoprotein particles (r-HDL). r-HDL were made from cholate mixed micelles that contained PC, apo AI, and, in some cases, unesterified cholesterol. r-HDL were characterized using chemical composition, nondenaturing gradient gel electrophoresis, transmission electron microscopy, and dynamic light scattering. The r-HDL were found to be discoidal and in the size range of native HDL. Upon treatment of cholesterol-containing r-HDL with lecithin-cholesterol acyltransferase (LCAT), to form cholesteryl ester, the discoidal r-HDL became spheroidal. The effects of r-HDL morphology and size on HL activity were studied on r-HDL made of palmitoyloleoyl-PC, unesterified cholesterol, cholesteryl ester, and apolipoprotein AI. Spheroidal r-HDL were hydrolyzed at a faster rate than discoidal r-HDL. Protein-poor r-HDL were hydrolyzed by HL at a faster rate than protein rich r-HDL. Unesterified cholesterol had no apparent effect on particle PC hydrolysis. The hydrolysis of different species of PC [dipalmitoyl (DPPC), dioleoyl(DOPC), palmitoylarachidonoyl (PAPC), and palmitoyloleoyl (POPC)] in r-HDL was also investigated. In discoidal r-HDL, we found that POPC >/= DOPC = PAPC/DPPC. However, in LCAT-treated spheroidal r-HDL, POPC = DOPC > PAPC/DPPC. In both discoidal and spheroidal rHDL, DPPC containing r-HDL were not hydrolyzed to a significant extent. Collectively, these studies demonstrate that the physico-chemical properties of particles (such as phospholipid packing and phospholipid acyl composition) play a significant role in hydrolysis of HDL phospholipid by HL and, therefore, in reverse cholesterol transport.

  1. Spheroidal degeneration in H626R TGFBI variant lattice dystrophy: a multimodality analysis.

    Science.gov (United States)

    Lai, Kevin; Reidy, Jason; Bert, Benjamin; Milman, Tatyana

    2014-07-01

    The aim of this study was to describe clinical, imaging, molecular genetic, histopathologic, immunohistochemical, and ultrastructural characteristics of coexistent amyloid and spheroidal degeneration-type deposits in a family with histidine-626-arginine transforming growth factor beta-induced (H626R TGFBI) variant lattice dystrophy. This is a retrospective clinical-pathological and genetic analysis of one family with H626R variant lattice dystrophy. Pedigree analysis showed an autosomal dominant inheritance pattern of the disease. Examination of 3 affected family members revealed asymmetric, thick, branching lattice-like deposits associated with corneal haze. Sequencing of the TGFBI gene revealed a high-penetrance disease-causing sequence variation (H626R CAT>CGT heterozygous). Optical coherence tomography demonstrated fusiform, poorly demarcated hyperechoic stromal deposits with focal hypoechoic central regions. Histology of the corneal discs from 2 affected family members showed stromal deposits consistent with TGFBI amyloid. Some amyloid deposits contained a central nidus of spheroidal degeneration-type material that demonstrated autofluorescence, stained with elastic and Masson trichrome stains, did not stain with periodic acid-Schiff or Congo red stains, was nonbirefringent, and did not immunoreact with keratoepithelin antibodies. Transmission electron microscopy confirmed the presence of amyloid fibrils with central, electrodense, homogeneous, discrete, spheroidal degeneration-type deposits. The presence of spheroidal deposits in a subset of affected patients, variability in presentation within an individual and between family members, predominant anterior corneal stromal location and nonimmunoreactivity of deposits for keratoepithelin suggest that these deposits are degenerative in nature. The deposits may arise from ultraviolet light-altered proteins diffused from the limbus, which form a nidus for keratoepithelin deposition.

  2. Imaging Herpes Simplex Virus Type 1 Amplicon Vector–Mediated Gene Expression in Human Glioma Spheroids

    OpenAIRE

    Christine Kaestle; Alexandra Winkeler; Raphaela Richter; Heinrich Sauer; Jürgen Hescheler; Cornel Fraefel; Maria Wartenberg; Andreas H. Jacobs

    2011-01-01

    Vectors derived from herpes simplex virus type 1 (HSV-1) have great potential for transducing therapeutic genes into the central nervous system; however, inefficient distribution of vector particles in vivo may limit their therapeutic potential in patients with gliomas. This study was performed to investigate the extent of HSV-1 amplicon vector–mediated gene expression in a three-dimensional glioma model of multicellular spheroids by imaging highly infectious HSV-1 virions expressing green fl...

  3. Cisplatin Resistant Spheroids Model Clinically Relevant Survival Mechanisms in Ovarian Tumors.

    Directory of Open Access Journals (Sweden)

    Winyoo Chowanadisai

    Full Text Available The majority of ovarian tumors eventually recur in a drug resistant form. Using cisplatin sensitive and resistant cell lines assembled into 3D spheroids we profiled gene expression and identified candidate mechanisms and biological pathways associated with cisplatin resistance. OVCAR-8 human ovarian carcinoma cells were exposed to sub-lethal concentrations of cisplatin to create a matched cisplatin-resistant cell line, OVCAR-8R. Genome-wide gene expression profiling of sensitive and resistant ovarian cancer spheroids identified 3,331 significantly differentially expressed probesets coding for 3,139 distinct protein-coding genes (Fc >2, FDR < 0.05 (S2 Table. Despite significant expression changes in some transporters including MDR1, cisplatin resistance was not associated with differences in intracellular cisplatin concentration. Cisplatin resistant cells were significantly enriched for a mesenchymal gene expression signature. OVCAR-8R resistance derived gene sets were significantly more biased to patients with shorter survival. From the most differentially expressed genes, we derived a 17-gene expression signature that identifies ovarian cancer patients with shorter overall survival in three independent datasets. We propose that the use of cisplatin resistant cell lines in 3D spheroid models is a viable approach to gain insight into resistance mechanisms relevant to ovarian tumors in patients. Our data support the emerging concept that ovarian cancers can acquire drug resistance through an epithelial-to-mesenchymal transition.

  4. Numerical simulation of water exit of an initially fully submerged buoyant spheroid in an axisymmetric flow

    Energy Technology Data Exchange (ETDEWEB)

    Ni, B Y; Wu, G X, E-mail: g.wu@ucl.ac.uk [College of Shipbuilding Engineering, Harbin Engineering University, Harbin 150001 (China)

    2017-08-15

    The free water exit of an initially fully submerged buoyant spheroid in an axisymmetric flow, which is driven by the difference between the vertical fluid force and gravity, is investigated. The fluid is assumed to be incompressible and inviscid, and the flow to be irrotational. The velocity potential theory is adopted together with fully nonlinear boundary conditions on the free surface. The surface tension is neglected and the pressure is taken as constant on the free surface. The acceleration of the body at each time step is obtained as part of the solution. Its nonlinear mutual dependence on the fluid force is decoupled through the auxiliary function method. The free-surface breakup by body penetration and water detachment from the body are treated through numerical conditions. The slender body theory based on the zero potential assumption on the undisturbed flat free surface is adopted, through which a condition for full water exit of a spheroid is obtained. Comparison is made between the results from the slender body theory and from the fully nonlinear theory through the boundary-element method, and good agreement is found when the spheroid is slender. Extensive case studies are undertaken to investigate the effects of body density, dimensions and the initial submergence. (paper)

  5. Characterization and reproducibility of HepG2 hanging drop spheroids toxicology in vitro.

    Science.gov (United States)

    Hurrell, Tracey; Ellero, Andrea Antonio; Masso, Zelie Flavienne; Cromarty, Allan Duncan

    2018-02-21

    Hepatotoxicity remains a major challenge in drug development despite preclinical toxicity screening using hepatocytes of human origin. To overcome some limitations of reproducing the hepatic phenotype, more structurally and functionally authentic cultures in vitro can be introduced by growing cells in 3D spheroid cultures. Characterisation and reproducibility of HepG2 spheroid cultures using a high-throughput hanging drop technique was performed and features contributing to potential phenotypic variation highlighted. Cultured HepG2 cells were seeded into Perfecta 3D® 96-well hanging drop plates and assessed over time for morphology, viability, cell cycle distribution, protein content and protein-mass profiles. Divergent aspects which were assessed included cell stocks, seeding density, volume of culture medium and use of extracellular matrix additives. Hanging drops are advantageous due to no complex culture matrix being present, enabling background free extractions for downstream experimentation. Varying characteristics were observed across cell stocks and batches, seeding density, culture medium volume and extracellular matrix when using immortalized HepG2 cells. These factors contribute to wide-ranging cellular responses and highlights concerns with respect to generating a reproducible phenotype in HepG2 hanging drop spheroids. Copyright © 2018 Elsevier Ltd. All rights reserved.

  6. Hyperspherical Coulomb spheroidal basis in the Coulomb three-body problem

    International Nuclear Information System (INIS)

    Abramov, D. I.

    2013-01-01

    A hyperspherical Coulomb spheroidal (HSCS) representation is proposed for the Coulomb three-body problem. This is a new expansion in the set of well-known Coulomb spheroidal functions. The orthogonality of Coulomb spheroidal functions on a constant-hyperradius surface ρ = const rather than on a constant-internuclear-distance surface R = const, as in the traditional Born-Oppenheimer approach, is a distinguishing feature of the proposed approach. Owing to this, the HSCS representation proves to be consistent with the asymptotic conditions for the scattering problem at energies below the threshold for three-body breakup: only a finite number of radial functions do not vanish in the limit of ρ→∞, with the result that the formulation of the scattering problem becomes substantially simpler. In the proposed approach, the HSCS basis functions are considerably simpler than those in the well-known adiabatic hyperspherical representation, which is also consistent with the asymptotic conditions. Specifically, the HSCS basis functions are completely factorized. Therefore, there arise no problems associated with avoided crossings of adiabatic hyperspherical terms.

  7. Dark Matter Searches with the Fermi-LAT in the Direction of Dwarf Spheroidals

    Energy Technology Data Exchange (ETDEWEB)

    Wood, Matthew; Anderson, Brandon; Drlica-Wagner, Alex; Cohen-Tanugi, Johann; Conrad, Jan

    2015-07-13

    The dwarf spheroidal satellite galaxies of the Milky Way are some of the most dark-matter-dominated objects known. Due to their proximity, high dark matter content, and lack of astrophysical backgrounds, dwarf spheroidal galaxies are widely considered to be among the most promising targets for the indirect detection of dark matter via gamma rays. Here we report on gamma-ray observations of Milky Way dwarf spheroidal satellite galaxies based on 6 years of Fermi Large Area Telescope data processed with the new Pass 8 reconstruction and event-level analysis. None of the dwarf galaxies are significantly detected in gamma rays, and we present upper limits on the dark matter annihilation cross section from a combined analysis of the 15 most promising dwarf galaxies. The constraints derived are among the strongest to date using gamma rays, and lie below the canonical thermal relic cross section for WIMPs of mass ≲ 100GeV annihilating via the bb-bar and τ⁺τ⁻ channels.

  8. Classification of materials for conducting spheroids based on the first order polarization tensor

    Science.gov (United States)

    Khairuddin, TK Ahmad; Mohamad Yunos, N.; Aziz, ZA; Ahmad, T.; Lionheart, WRB

    2017-09-01

    Polarization tensor is an old terminology in mathematics and physics with many recent industrial applications including medical imaging, nondestructive testing and metal detection. In these applications, it is theoretically formulated based on the mathematical modelling either in electrics, electromagnetics or both. Generally, polarization tensor represents the perturbation in the electric or electromagnetic fields due to the presence of conducting objects and hence, it also desribes the objects. Understanding the properties of the polarization tensor is necessary and important in order to apply it. Therefore, in this study, when the conducting object is a spheroid, we show that the polarization tensor is positive-definite if and only if the conductivity of the object is greater than one. In contrast, we also prove that the polarization tensor is negative-definite if and only if the conductivity of the object is between zero and one. These features categorize the conductivity of the spheroid based on in its polarization tensor and can then help to classify the material of the spheroid.

  9. Thermal Plasma Spheroidization of High-Nitrogen Stainless Steel Powder Alloys Synthesized by Mechanical Alloying

    Science.gov (United States)

    Razumov, Nikolay G.; Popovich, Anatoly A.; Wang, QingSheng

    2018-03-01

    This paper presents the results of experimental studies on the treatment of Fe-23Cr-11Mn-1N high-nitrogen stainless steel powder alloys, synthesized by the mechanical alloying (MA) of elemental powders in the flow of a thermal plasma. Fe-23Cr-11Mn-1N high-nitrogen stainless steel powder alloys were prepared by MA in the attritor under an argon atmosphere. For spheroidization of Fe-23Cr-11Mn-1N high-nitrogen stainless steel powder alloys, the TekSphero 15 plant manufactured by Tekna Plasma Systems Inc was used. The studies have shown the possibility of obtaining Fe-23Cr-11Mn-1N high-nitrogen spherical powders steel alloys from the powder obtained by MA. According to the results of a series of experiments, it was found that the results of plasma spheroidization of powders essentially depend on the size of the fraction due to some difference in the particle shape and flowability, and on the gas regime of the plasma torch. It is established that during the plasma spheroidization process, some of the nitrogen leaves the alloy. The loss rate of nitrogen depends on the size of the initial particles.

  10. Study of the boxlike dark matter signals from dwarf spheroidal galaxies with Fermi-LAT data

    Science.gov (United States)

    Li, Shang; Liang, Yun-Feng; Xia, Zi-Qing; Zu, Lei; Duan, Kai-Kai; Shen, Zhao-Qiang; Feng, Lei; Yuan, Qiang; Fan, Yi-Zhong

    2018-04-01

    The observation of a special spectral feature in the gamma-ray data would be one of the best ways to identify dark matter (DM). The box-shaped gamma-ray spectra could be generated by the decay of intermediate particles produced by DM annihilation or decay. It provides another kind of signal that can be relatively easily distinguished from astrophysical backgrounds besides the linelike signals. Dwarf spheroidal galaxies are expected to be dominated by DM and may be one of the most promising targets for indirect DM searches. In this paper, we study the box-shaped DM signals with Fermi-LAT observations of dwarf spheroidal galaxies. We analyze 106 months of Fermi-LAT data to derive the upper limits on the annihilation cross section or the decay timescale of DM. In addition, we compare the results for different sample selections and DM density distributions. We expect that more dwarf spheroidal galaxies will be found and the sensitivity of box-shaped gamma-ray signal searches will be significantly improved in the future.

  11. The distribution of alternative agents for targeted radiotherapy within human neuroblastoma spheroids

    International Nuclear Information System (INIS)

    Mairs, R.J.; Gaze, M.N.; Murray, T.; Reid, R.; McSharry, C.; Babich, J.W.

    1991-01-01

    This study aims to select the radiopharmaceutical vehicle for targeted radiotherapy of neuroblastoma which is most likely to penetrate readily the centre of micrometastases in vivo. The human neuroblastoma cell line NB1-G, grown as multicellular spheroids provided an in vitro model for micrometastases. The radiopharmaceuticals studied were the catecholamine analogue metaiodobenzyl guanidine (mIBG), a specific neuroectodermal monoclonal antibody (UJ13A) and β nerve growth factor (βNGF). Following incubation of each drug with neuroblastoma spheroids, autoradiographs of frozen sections were prepared to demonstrate their relative distributions. mIBG and βNGF were found to penetrate the centre of spheroids readily although the concentration of mIBG greatly exceeded that of βNGF. In contrast, UJ13A was only bound peripherally. We conclude that mIBG is the best available vehicle for targeted radiotherapy of neuroblastoma cells with active uptake mechanisms for catecholimines. It is suggested that radionuclides with a shorter range of emissions than 131 I may be conjugated to benzyl guanidine to constitute more effective targeting agents with potentially less toxicity to adjacent normal tissues. (author)

  12. Vorinostat eliminates multicellular resistance of mesothelioma 3D spheroids via restoration of Noxa expression.

    Directory of Open Access Journals (Sweden)

    Dario Barbone

    Full Text Available When grown in 3D cultures as spheroids, mesothelioma cells acquire a multicellular resistance to apoptosis that resembles that of solid tumors. We have previously found that resistance to the proteasome inhibitor bortezomib in 3D can be explained by a lack of upregulation of Noxa, the pro-apoptotic BH3 sensitizer that acts via displacement of the Bak/Bax-activator BH3-only protein, Bim. We hypothesized that the histone deacetylase inhibitor vorinostat might reverse this block to Noxa upregulation in 3D. Indeed, we found that vorinostat effectively restored upregulation of Noxa protein and message and abolished multicellular resistance to bortezomib in the 3D spheroids. The ability of vorinostat to reverse resistance was ablated by knockdown of Noxa or Bim, confirming the essential role of the Noxa/Bim axis in the response to vorinostat. Addition of vorinostat similarly increased the apoptotic response to bortezomib in another 3D model, the tumor fragment spheroid, which is grown from human mesothelioma ex vivo. In addition to its benefit when used with bortezomib, vorinostat also enhanced the response to cisplatin plus pemetrexed, as shown in both 3D models. Our results using clinically relevant 3D models show that the manipulation of the core apoptotic repertoire may improve the chemosensitivity of mesothelioma. Whereas neither vorinostat nor bortezomib alone has been clinically effective in mesothelioma, vorinostat may undermine chemoresistance to bortezomib and to other therapies thereby providing a rationale for combinatorial strategies.

  13. Vorinostat Eliminates Multicellular Resistance of Mesothelioma 3D Spheroids via Restoration of Noxa Expression

    Science.gov (United States)

    Barbone, Dario; Cheung, Priscilla; Battula, Sailaja; Busacca, Sara; Gray, Steven G.; Longley, Daniel B.; Bueno, Raphael; Sugarbaker, David J.; Fennell, Dean A.; Broaddus, V. Courtney

    2012-01-01

    When grown in 3D cultures as spheroids, mesothelioma cells acquire a multicellular resistance to apoptosis that resembles that of solid tumors. We have previously found that resistance to the proteasome inhibitor bortezomib in 3D can be explained by a lack of upregulation of Noxa, the pro-apoptotic BH3 sensitizer that acts via displacement of the Bak/Bax-activator BH3-only protein, Bim. We hypothesized that the histone deacetylase inhibitor vorinostat might reverse this block to Noxa upregulation in 3D. Indeed, we found that vorinostat effectively restored upregulation of Noxa protein and message and abolished multicellular resistance to bortezomib in the 3D spheroids. The ability of vorinostat to reverse resistance was ablated by knockdown of Noxa or Bim, confirming the essential role of the Noxa/Bim axis in the response to vorinostat. Addition of vorinostat similarly increased the apoptotic response to bortezomib in another 3D model, the tumor fragment spheroid, which is grown from human mesothelioma ex vivo. In addition to its benefit when used with bortezomib, vorinostat also enhanced the response to cisplatin plus pemetrexed, as shown in both 3D models. Our results using clinically relevant 3D models show that the manipulation of the core apoptotic repertoire may improve the chemosensitivity of mesothelioma. Whereas neither vorinostat nor bortezomib alone has been clinically effective in mesothelioma, vorinostat may undermine chemoresistance to bortezomib and to other therapies thereby providing a rationale for combinatorial strategies. PMID:23300762

  14. Apoptosis, energy metabolism, and fraction of radiobiologically hypoxic cells: a study of human melanoma multicellular spheroids.

    Science.gov (United States)

    Rofstad, E K; Eide, K; Skøyum, R; Hystad, M E; Lyng, H

    1996-09-01

    The magnitude of the fraction of radiobiologically hypoxic cells in tumours is generally believed to reflect the efficiency of the vascular network. Theoretical studies have suggested that the hypoxic fraction might also be influenced by biological properties of the tumour cells. Quantitative experimental results of cell energy metabolism, hypoxia- induced apoptosis, and radiobiological hypoxia are reported here. Human melanoma multicellular spheroids (BEX-c and WIX-c) were used as tumour models to avoid confounding effects of the vascular network. Radiobiological studies showed that the fractions of hypoxic cells in 1000-microM spheroids were 32 +/- 12% (BEX-c) and 2.5 +/- 1.1% (WIX-c). The spheroid hypoxic volume fractions (28 +/- 6% (BEX-c) and 1.4 +/- 7% (WIX-c)), calculated from the rate of oxygen consumption per cell, the cell packing density, and the thickness of the viable rim, were similar to the fractions of radiobiologically hypoxic cells. Large differences between tumours in fraction of hypoxic cells are therefore not necessarily a result of differences in the efficiency of the vascular network. Studies of monolayer cell cultures, performed to identify the biological properties of the BEX-c and WIX-c cells leading to this large difference in fraction of hypoxic cells, gave the following results: (1) WIX-c showed lower cell surviving fractions after exposure to hypoxia than BEX-c, (2) WIX-c showed higher glucose uptake and lactate release rates than BEX-c both under aerobic and hypoxic conditions, and (3) hypoxia induced apoptosis in WIX-c but not in BEX-c. These observations suggested that the difference between BEX-c and WIX-c spheroids in fraction of hypoxic cells resulted partly from differences in cell energy metabolism and partly from a difference in capacity to retain viability under hypoxic stress. The induction of apoptosis by hypoxia was identified as a phenomenon which has an important influence on the magnitude of the fraction of

  15. Human adipose-derived stem cell spheroid treated with photobiomodulation irradiation accelerates tissue regeneration in mouse model of skin flap ischemia.

    Science.gov (United States)

    Park, In-Su; Chung, Phil-Sang; Ahn, Jin Chul; Leproux, Anais

    2017-11-01

    Skin flap grafting is a form of transplantation widely used in plastic surgery. However, ischemia/reperfusion injury is the main factor which reduces the survival rate of flaps following grafting. We investigated whether photobiomodulation (PBM) precondition prior to human adipose-derived stromal cell (hASC) spheroid (PBM-spheroid) transplantation improved skin tissue functional recovery by the stimulation of angiogenesis and tissue regeneration in skin flap of mice. The LED had an emission wavelength peaked at 660 ± 20 nm (6 J/cm 2 , 10 mW/cm 2 ). The expression of angiogenic growth factors in PBM-spheroid hASCs was much greater than that of not-PBM-treated spheroid or monolayer-cultured hASCs. From immunochemical staining analysis, the hASCs of PBM-spheroid were CD31 + , KDR + , and CD34 + , whereas monolayer-cultured hASCs were negative for these markers. To evaluate the therapeutic effect of hASC PBM-spheroid in vivo, PBS, monolayer-cultured hASCs, and not-PBM-spheroid were transplanted into a skin flap model. The animals were observed for 14 days. The PBM-spheroid hASCs transplanted into the skin flap ischemia differentiated into endothelial cells and remained differentiated. Transplantation of PBM-spheroid hASCs into the skin flap ischemia significantly elevated the density of vascular formations through angiogenic factors released by the skin flap ischemia and enhanced tissue regeneration at the lesion site. Consistent with these results, the transplantation of PBM-spheroid hASCs significantly improved functional recovery compared with PBS, monolayer-cultured hASCs, and not-PBM-spheroid treatment. These findings suggest that transplantation of PBM-spheroid hASCs may be an effective stem cell therapy for the treatment of skin flap ischemia.

  16. Molluscan shell evolution with review of shell calcification hypothesis

    Czech Academy of Sciences Publication Activity Database

    Furuhashi, T.; Schwarzinger, C.; Mikšík, Ivan; Smrž, Miloslav; Beran, A.

    2009-01-01

    Roč. 154, č. 3 (2009), s. 351-371 ISSN 1096-4959 Institutional research plan: CEZ:AV0Z50110509 Keywords : mollusca * shell * biomineralization Subject RIV: CE - Biochemistry Impact factor: 1.607, year: 2009

  17. MicroShell Minimalist Shell for Xilinx Microprocessors

    Science.gov (United States)

    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

  18. Clustering correlations and triaxiality in the sd-shell region

    International Nuclear Information System (INIS)

    Taniguchi, Yasutaka; Kimura, Masaaki; Kanada-En'yo, Yoshiko; Horiuchi, Hisashi

    2011-01-01

    Effects of cluster correlations on triaxiality have been studied using the antisymmetrized molecular dynamics. Low-lying states in 28 Si and 40 Ca are obtained by the generator coordinate method (GCM), and the GCM basis are calculated by energy variations with constraints on quadrupole deformation parameter β and inter-cluster distance. The GCM obtain prolate superdeformed (SD) states in 28 Si and triaxial normal-deformed (ND) states in 40 Ca, which contain prolate α- 24 Mg and triaxial α- 36 Ar cluster structure components, respectively. Different shapes of prolate 24 Mg and oblate 36 Ar clusters cause difference of triaxiality of total systems. Cluster correlations which have oblate cluster enhance triaxiality in excited states. (author)

  19. Spheroid Culture of Head and Neck Cancer Cells Reveals an Important Role of EGFR Signalling in Anchorage Independent Survival.

    Science.gov (United States)

    Braunholz, Diana; Saki, Mohammad; Niehr, Franziska; Öztürk, Merve; Borràs Puértolas, Berta; Konschak, Robert; Budach, Volker; Tinhofer, Ingeborg

    2016-01-01

    In solid tumours millions of cells are shed into the blood circulation each day. Only a subset of these circulating tumour cells (CTCs) survive, many of them presumable because of their potential to form multi-cellular clusters also named spheroids. Tumour cells within these spheroids are protected from anoikis, which allows them to metastasize to distant organs or re-seed at the primary site. We used spheroid cultures of head and neck squamous cell carcinoma (HNSCC) cell lines as a model for such CTC clusters for determining the role of the epidermal growth factor receptor (EGFR) in cluster formation ability and cell survival after detachment from the extra-cellular matrix. The HNSCC cell lines FaDu, SCC-9 and UT-SCC-9 (UT-SCC-9P) as well as its cetuximab (CTX)-resistant sub-clone (UT-SCC-9R) were forced to grow in an anchorage-independent manner by coating culture dishes with the anti-adhesive polymer poly-2-hydroxyethylmethacrylate (poly-HEMA). The extent of apoptosis, clonogenic survival and EGFR signalling under such culture conditions was evaluated. The potential of spheroid formation in suspension culture was found to be positively correlated with the proliferation rate of HNSCC cell lines as well as their basal EGFR expression levels. CTX and gefitinib blocked, whereas the addition of EGFR ligands promoted anchorage-independent cell survival and spheroid formation. Increased spheroid formation and growth were associated with persistent activation of EGFR and its downstream signalling component (MAPK/ERK). Importantly, HNSCC cells derived from spheroid cultures retained their clonogenic potential in the absence of cell-matrix contact. Addition of CTX under these conditions strongly inhibited colony formation in CTX-sensitive cell lines but not their resistant subclones. Altogether, EGFR activation was identified as crucial factor for anchorage-independent survival of HNSCC cells. Targeting EGFR in CTC cluster formation might represent an attractive anti

  20. Instant Windows PowerShell

    CERN Document Server

    Menon, Vinith

    2013-01-01

    Get to grips with a new technology, understand what it is and what it can do for you, and then get to work with the most important features and tasks. A practical, hands-on tutorial approach that explores the concepts of PowerShell in a friendly manner, taking an adhoc approach to each topic.If you are an administrator who is new to PowerShell or are looking to get a good grounding in these new features, this book is ideal for you. It's assumed that you will have some experience in PowerShell and Windows Server, as well being familiar with the PowerShell command-line.

  1. Patterning of the turtle shell.

    Science.gov (United States)

    Moustakas-Verho, Jacqueline E; Cebra-Thomas, Judith; Gilbert, Scott F

    2017-08-01

    Interest in the origin and evolution of the turtle shell has resulted in a most unlikely clade becoming an important research group for investigating morphological diversity in developmental biology. Many turtles generate a two-component shell that nearly surrounds the body in a bony exoskeleton. The ectoderm covering the shell produces epidermal scutes that form a phylogenetically stable pattern. In some lineages, the bones of the shell and their ectodermal covering become reduced or lost, and this is generally associated with different ecological habits. The similarity and diversity of turtles allows research into how changes in development create evolutionary novelty, interacting modules, and adaptive physiology and anatomy. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. 40 Years of Shell Scenarios

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2013-02-15

    Shell has been using scenario planning for four decades. During that time these scenarios have helped the company and governments across the world to make better strategic choices. Scenarios provide lenses that help see future prospects more clearly, make richer judgments and be more sensitive to uncertainties. Discover how the Shell Scenarios team has helped guide decision makers at major moments in history and get a peek at the team future focus, including the intricate relationship between energy, water and food.

  3. Nucleation and growth characteristics of graphite spheroids in bainite during graphitization annealing of a medium carbon steel

    International Nuclear Information System (INIS)

    Gao, J.X.; Wei, B.Q.; Li, D.D.; He, K.

    2016-01-01

    The evolution of microstructure in bainite during graphitization annealing at 680 °C of Jominy-quenched bars of an Al-Si bearing medium carbon (0.4C wt%) steel has been studied and compared with that in martensite by using light, scanning and transmission electron microscopy. The results show that the graphitization process in bainite is different from that in martensite in many aspects such as the initial carbon state, the behavior of cementite, the nucleation-growth feature and kinetics of formation of graphite spheroids during graphitization annealing, and the shape, size and distribution of these graphite spheroids. The fact that the graphitization in bainite can produce more homogeneous graphite spheroids with more spherical shape and finer size in a shorter annealing time without the help of preexisting coring particles implies that bainite should be a better starting structure than martensite for making graphitic steel. - Highlights: • This article presents a microstructural characterization of formation of graphite spheroids in bainite. • Nucleation and growth characteristics of graphite spheroids formed in bainite and martensite are compared. • Bainite should be a better starting structure for making graphitic steel as results show.

  4. Chondroitin sulfate microparticles modulate transforming growth factor-β1-induced chondrogenesis of human mesenchymal stem cell spheroids.

    Science.gov (United States)

    Goude, Melissa C; McDevitt, Todd C; Temenoff, Johnna S

    2014-01-01

    Mesenchymal stem cells (MSCs) have been previously explored as a part of cell-based therapies for the repair of damaged cartilage. Current MSC chondrogenic differentiation strategies employ large pellets; however, we have developed a technique to form small MSC aggregates (500-1,000 cells) that can reduce transport barriers while maintaining a multicellular structure analogous to cartilaginous condensations. The objective of this study was to examine the effects of incorporating chondroitin sulfate methacrylate (CSMA) microparticles (MPs) within small MSC spheroids cultured in the presence of transforming growth factor (TGF)-β1 on chondrogenesis. Spheroids with MPs induced earlier increases in collagen II and aggrecan gene expression (chondrogenic markers) than spheroids without MPs, although no large differences in immunostaining for these matrix molecules were observed by day 21 between these groups. Collagen I and X were also detected in the extracellular matrix (ECM) of all spheroids by immunostaining. Interestingly, histology revealed that CSMA MPs clustered together near the center of the MSC spheroids and induced circumferential alignment of cells and ECM around the material core. This study demonstrates the use of CSMA materials to further examine the effects of matrix molecules on MSC phenotype as well as potentially direct differentiation in a more spatially controlled manner that better mimics the architecture of specific musculoskeletal tissues. © 2014 S. Karger AG, Basel.

  5. Short-term spheroid culture of primary colorectal cancer cells as an in vitro model for personalizing cancer medicine

    DEFF Research Database (Denmark)

    Jeppesen, Maria; Hagel, Grith; Glenthoj, Anders

    2017-01-01

    Chemotherapy treatment of cancer remains a challenge due to the molecular and functional heterogeneity displayed by tumours originating from the same cell type. The pronounced heterogeneity makes it difficult for oncologists to devise an effective therapeutic strategy for the patient. One approac...... and combinations most commonly used for treatment of colorectal cancer. In summary, short-term spheroid culture of primary colorectal adenocarcinoma cells represents a promising in vitro model for use in personalized medicine....... for increasing treatment efficacy is to test the chemosensitivity of cancer cells obtained from the patient's tumour. 3D culture represents a promising method for modelling patient tumours in vitro. The aim of this study was therefore to evaluate how closely short-term spheroid cultures of primary colorectal...... cancer cells resemble the original tumour. Colorectal cancer cells were isolated from human tumour tissue and cultured as spheroids. Spheroid cultures were established with a high success rate and remained viable for at least 10 days. The spheroids exhibited significant growth over a period of 7 days...

  6. A Cardiac Cell Outgrowth Assay for Evaluating Drug Compounds Using a Cardiac Spheroid-on-a-Chip Device

    Directory of Open Access Journals (Sweden)

    Jonas Christoffersson

    2018-05-01

    Full Text Available Three-dimensional (3D models with cells arranged in clusters or spheroids have emerged as valuable tools to improve physiological relevance in drug screening. One of the challenges with cells cultured in 3D, especially for high-throughput applications, is to quickly and non-invasively assess the cellular state in vitro. In this article, we show that the number of cells growing out from human induced pluripotent stem cell (hiPSC-derived cardiac spheroids can be quantified to serve as an indicator of a drug’s effect on spheroids captured in a microfluidic device. Combining this spheroid-on-a-chip with confocal high content imaging reveals easily accessible, quantitative outgrowth data. We found that effects on outgrowing cell numbers correlate to the concentrations of relevant pharmacological compounds and could thus serve as a practical readout to monitor drug effects. Here, we demonstrate the potential of this semi-high-throughput “cardiac cell outgrowth assay” with six compounds at three concentrations applied to spheroids for 48 h. The image-based readout complements end-point assays or may be used as a non-invasive assay for quality control during long-term culture.

  7. Effect of combined treatment of x-rays and ACNU on rat glioma cells in monolayer and multicellular spheroids

    International Nuclear Information System (INIS)

    Sugiyama, Satoru; Mori, Teruaki; Suzuki, Jiro; Sasaki, Takehito

    1985-01-01

    Spheroids of rat glioma clone-6 cells having a central necrosis were used to determine the effect of combined treatment of x-rays and 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-(2-chloroethyl)-3-nitrosourea hydrochloride (ACNU), where the optimum time intervals and doses in the combination were analyzed. The treatment with ACNU 2 to 6 hours prior to x-ray irradiation was most effective for cells in both monolayers and in spheroids. The dose survival curves with x-ray irradiation indicated that the hypoxic cell fraction in spheroids disappeared with a prior treatment by ACNU. The enhancement ratio in spheroids was thus larger for larger x-ray doses, and was always larger than that in monolayer cells. The survival curves versus concentration of ACNU indicated that the enhancement ratio in spheroids was more than 1.2 in all concentrations with the combined x-ray irradiation, and exceeded that in monolayer cells with a surviving fraction of less than 0.4. (author)

  8. Human adipose stem cells maintain proliferative, synthetic and multipotential properties when suspension cultured as self-assembling spheroids

    International Nuclear Information System (INIS)

    Kapur, S K; Wang, X; Shang, H; Yun, S; Li, X; Feng, G; Khurgel, M; Katz, A J

    2012-01-01

    Adipose-derived stromal/stem cells (ASCs) have been gaining recognition as an extremely versatile cell source for tissue engineering. The usefulness of ASCs in biofabrication is further enhanced by our demonstration of the unique properties of these cells when they are cultured as three-dimensional cellular aggregates or spheroids. As described herein, three-dimensional formulations, or self-assembling ASC spheroids develop their own extracellular matrix that serves to increase the robustness of the cells to mechanical stresses. The composition of the extracellular matrix can be altered based on the external environment of the spheroids and these constructs can be grown in a reproducible manner and to a consistent size. The spheroid formulation helps preserve the viability and developmental plasticity of ASCs even under defined, serum-free media conditions. For the first time, we show that multiple generations of adherent ASCs produced from these spheroids retain their ability to differentiate into multiple cell/tissue types. These demonstrated properties support the idea that culture-expanded ASCs are an excellent candidate cellular material for ‘organ printing’—the approach of developing complex tissue structures from a standardized cell ‘ink’ or cell formulation. (paper)

  9. Isogeometric shell formulation based on a classical shell model

    KAUST Repository

    Niemi, Antti

    2012-09-04

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

  10. Homogeneous pancreatic cancer spheroids mimic growth pattern of circulating tumor cell clusters and macrometastases: displaying heterogeneity and crater-like structure on inner layer.

    Science.gov (United States)

    Feng, Hao; Ou, Bao-Chi; Zhao, Jing-Kun; Yin, Shuai; Lu, Ai-Guo; Oechsle, Eva; Thasler, Wolfgang E

    2017-09-01

    Pancreatic cancer 3D in vitro models including multicellular tumor spheroid (MCTS), single cell-derived tumor spheroid (SCTS), tissue-derived tumor spheroid, and organotypic models provided powerful platforms to mimic in vivo tumor. Recent work supports that circulating tumor cell (CTC) clusters are more efficient in metastasis seeding than single CTCs. The purpose of this study is to establish 3D culture models which can mimic single CTC, monoclonal CTC clusters, and the expansion of macrometastases. Seven pancreatic ductal adenocarcinoma cell lines were used to establish MCTS and SCTS using hanging drop and ultra-low attachment plates. Spheroid immunofluorescence staining, spheroid formation assay, immunoblotting, and literature review were performed to investigate molecular biomarkers and the morphological characteristics of pancreatic tumor spheroids. Single cells experienced different growth patterns to form SCTS, like signet ring-like cells, blastula-like structures, and solid core spheroids. However, golf ball-like hollow spheroids could also be detected, especially when DanG and Capan-1 cells were cultivated with fibroblast-conditioned medium (p cell lines could also establish tumor spheroid with hanging drop plates by adding methylated cellulose. Tumor spheroids derived from pancreatic cancer cell line DanG possessed asymmetrically distributed proliferation center, immune-checkpoint properties. ß-catenin, Ki-67, and F-actin were active surrounding the crater-like structure distributing on the inner layer of viable rim cover of the spheroids, which was relevant to well-differentiated tumor cells. It is possible to establish 3D CTC cluster models from homogenous PDA cell lines using hanging drop and ultra-low attachment plates. PDA cell line displays its own intrinsic properties or heterogeneity. The mechanism of formation of the crater-like structure as well as golf ball-like structure needs further exploration.

  11. Creep buckling of shells

    International Nuclear Information System (INIS)

    Stone, C.M.; Nickell, R.E.

    1977-01-01

    Because of the characteristics of LMFBR primary piping components (thin-walled, low pressure, high temperature), the designer must guard against creep buckling as a potential failure mode for certain critical regions, such as elbows, where structural flexibility and inelastic response may combine to concentrate deformation and cause instability. The ASME Boiler and Pressure Vessel Code, through its elevated temperature Code Case 1592 (Section III, Division 1) provides design rules for Class 1 components aimed at preventing creep buckling during the design life. A similar set of rules is being developed for Class 2 and 3 components at this time. One of the original concepts behind the creep buckling rules was that the variability in creep properties (especially due to the effects of prior heat treatment), the uncertainty about initial imperfections, and the lack of confirmed accuracy of design analysis meant that conservatism would be difficult to assure. As a result, a factor of ten on service life was required (i.e. analysis must show that, under service conditions that extrapolate the life of the component by ten times, creep buckling does not occur). Two obvious problems with this approach are that: first, the creep behavior must also be extrapolated (since most creep experiments are terminated at a small fraction of the design life, extrapolation of creep data is already an issue, irrespective of the creep buckling question); second the nonlinear creep analysis, which is very nearly prohibitively expensive for design life histograms, becomes even more costly. Analytical results for an aluminum cylindrical shell subjected to axial loads at elevated temperatures are used to examine the supposed equivalence of two types of time-dependent buckling safety factors - a factor of ten on service life and a factor of 1.5 on loading

  12. Generation of Homogenous Three-Dimensional Pancreatic Cancer Cell Spheroids Using an Improved Hanging Drop Technique.

    Science.gov (United States)

    Ware, Matthew J; Colbert, Kevin; Keshishian, Vazrik; Ho, Jason; Corr, Stuart J; Curley, Steven A; Godin, Biana

    2016-04-01

    In vitro characterization of tumor cell biology or of potential anticancer drugs is usually performed using tumor cell lines cultured as a monolayer. However, it has been previously shown that three-dimensional (3D) organization of the tumor cells is important to provide insights on tumor biology and transport of therapeutics. Several methods to create 3D tumors in vitro have been proposed, with hanging drop technique being the most simple and, thus, most frequently used. However, in many cell lines this method has failed to form the desired 3D tumor structures. The aim of this study was to design and test an easy-to-use and highly reproducible modification of the hanging drop method for tumor sphere formation by adding methylcellulose polymer. Most pancreatic cancer cells do not form cohesive and manageable spheres when the original hanging drop method is used, thus we investigated these cell lines for our modified hanging drop method. The spheroids produced by this improved technique were analyzed by histology, light microscopy, immunohistochemistry, and scanning electron microscopy. Results show that using the proposed simple method; we were able to produce uniform spheroids for all five of the tested human pancreatic cancer cell lines; Panc-1, BxPC-3, Capan-1, MiaPaCa-2, and AsPC-1. We believe that this method can be used as a reliable and reproducible technique to make 3D cancer spheroids for use in tumor biology research and evaluation of therapeutic responses, and for the development of bio-artificial tissues.

  13. Determination of Drug Toxicity Using 3D Spheroids Constructed From an Immortal Human Hepatocyte Cell Line

    Science.gov (United States)

    Fey, Stephen J.; Wrzesinski, Krzysztof

    2012-01-01

    Numerous publications have documented that the immortal cells grown in three-dimensional (3D) cultures possess physiological behavior, which is more reminiscent of their parental organ than when the same cells are cultivated using classical two-dimensional (2D) culture techniques. The goal of this study was to investigate whether this observation could be extended to the determination of LD50 values and whether 3D data could be correlated to in vivo observations. We developed a noninvasive means to estimate the amount of protein present in a 3D spheroid from it is planar area (± 21%) so that a precise dose can be provided in a manner similar to in vivo studies. This avoided correction of the actual dose given based on a protein determination after treatment (when some cells may have lysed). Conversion of published in vitro LC50 data (mM) for six common drugs (acetaminophen, amiodarone, diclofenac, metformin, phenformin, and valproic acid) to LD50 data (mg compound/mg cellular protein) showed that the variation in LD50 values was generally less than that suggested by the original LC50 data. Toxicological analysis of these six compounds in 3D spheroid culture (either published or presented here) demonstrated similar LD50 values. Although in vitro 2D HepG2 data showed a poor correlation, the primary hepatocyte and 3D spheroid data resulted in a much higher degree of correlation with in vivo lethal blood plasma levels. These results corroborate that 3D hepatocyte cultures are significantly different from 2D cultures and are more representative of the liver in vivo. PMID:22454432

  14. Detailed abundances in stars belonging to ultra-faint dwarf spheroidal galaxies

    OpenAIRE

    François, P.; Monaco, L.; Villanova, S.; Catelan, M.; Bonifacio, P.; Bellazzini, M.; Bidin, C. Moni; Marconi, G.; Geisler, D.; Sbordone, L.

    2012-01-01

    We report preliminary results concerning the detailed chemical composition of metal poor stars belonging to close ultra-faint dwarf galaxies (hereafter UfDSphs). The abundances have been determined thanks to spectra obtained with X-Shooter, a high efficiency spectrograph installed on one of the ESO VLT units. The sample of ultra-faint dwarf spheroidal stars have abundance ratios slightly lower to what is measured in field halo star of the same metallicity.We did not find extreme abundances in...

  15. Stars of the Draco Dwarf Spheroidal Galaxy Beyond its Measured Tidal Boundary

    OpenAIRE

    Piatek, Slawomir; Pryor, Carlton; Armandroff, Taft E.; Olszewski, Edward W.

    2000-01-01

    We report R- and V-band photometry derived from CCD imaging for objects in nine fields in and around the Draco dwarf spheroidal galaxy. The most distant fields are about 1.3 degrees from the center. We use these data to search for Draco stars outside of its measured tidal boundary. The search involves three methods: 1) Plotting color-magnitude diagrams for individual fields, for sections of fields, and for combined fields and sections. A color-magnitude diagram can reveal a population of Drac...

  16. The Dwarf Spheroidal Companions to M31: WFPC2 Observations of Andromeda III

    OpenAIRE

    Da Costa, G. S.; Armandroff, T. E.; Caldwell, Nelson

    2002-01-01

    The Hubble Space Telescope WFPC2 camera has been used to image Andromeda III, a dwarf spheroidal companion (dSph) to M31. The resulting color-magnitude (c-m) diagrams reveal the morphology of the horizontal branch (HB) in this dwarf galaxy. We find that like Andromeda I and Andromeda II, and like most of the Galactic dSph companions, the HB morphology of And III is predominantly red, redder than that of both And I and And II despite And III having a lower mean metallicity. We interpret this r...

  17. A program to compute the area of an irregular polygon on a spheroidal surface

    Digital Repository Service at National Institute of Oceanography (India)

    Sivakholundu, K.M.; Prabaharan, N.

    (MATLAB). Short Note824 lar shapes. The analytical integrations were carried out with the software package MATLAB on a SUN workstation. The comparisons were made to check: 1. The eC128ect of varying strip width for integration. 2. Variation of accuracy... this program can be used to calculate the area on the spheroidal surface for irregular shapes without losing accuracy. REFERENCES Bomford, G. (1977) Geodesy. Oxford University Press, 731 pp. Larkin, B. J. (1988) A FORTRAN 77 program to calcu- late areas...

  18. Isoprenoid hydrocarbons produced by thermal alteration of Nostoc muscorum and Rhodopseudomonas spheroides

    Science.gov (United States)

    Philp, R. P.; Brown, S.; Calvin, M.

    1978-01-01

    The potential of algae and photosynthetic bacteria to serve as precursors of kerogen was studied to determine what factors affect the relative rates of formation of precursor hydrocarbons. Cells of Nostoc muscorum and Rhodopseudomonas spheroides were subjected to thermal alteration (by heating samples in glass tubes sealed under nitrogen) for two, four, and twelve weeks. Both unextracted and extracted cells in the absence and presence of montmorillonite were investigated, and the isoprenoid hydrocarbons produced in these experiments were determined. Phytane and five isomeric phytenes were the main hydrocarbons observed; their relative rates of formation in the different experimental conditions are described. No phytadienes, pristane, or pristenes were detected.

  19. The therapeutic potential of three-dimensional multipotent mesenchymal stromal cell spheroids

    Czech Academy of Sciences Publication Activity Database

    Petrenko, Yuriy; Syková, Eva; Kubinová, Šárka

    2017-01-01

    Roč. 8, apr 26 (2017), s. 94 ISSN 1757-6512 R&D Projects: GA MŠk(CZ) LO1309; GA ČR(CZ) GA15-01396S; GA ČR(CZ) GA17-03765S; GA MŠk(CZ) LM2015064 Institutional support: RVO:68378041 Keywords : multipotent mesenchymal stromal cells * three-dimensional spheroids * clinical-grade manufacturing Subject RIV: FH - Neurology OBOR OECD: Neuroscience s (including psychophysiology Impact factor: 4.211, year: 2016

  20. High-purity tungsten powder: spheroidizing, properties and use in electronics

    International Nuclear Information System (INIS)

    Kapustin, V.I.; Burov, I.V.

    1999-01-01

    A study was made on the method of spheroidizing of tungsten powder in plasma of super high-frequency (SHF) discharge for formation of matrices, cathodes with regular porous structure. Kinetics of interphase interaction in the basic W-Y 2 O 3 cathode system was investigated. Possibility of using small additions of Re 2 Yintermetallic compound as an activator of emission-active component of cathodes was analyzed, High efficiency of plasma SHF-treatment with the use of laminar plasma flow is shown [ru

  1. The effect of microstructure of low-alloy spheroidal cast iron on impact strength

    Directory of Open Access Journals (Sweden)

    T. Szykowny

    2010-01-01

    Full Text Available The study presents an evaluation of the effect of microstructure of low-alloy spheroidal cast iron on impact strength within the temperature range from –60 to 100°C. Analyses were conducted on one type of cast iron containing 0.51% Cu and 0.72% Ni. Cast iron was austempered or normalized. Values of KCV and static mechanical properties were determined. Structural and fractographic analyses were based on light and scanning microscopy as well as X-ray diffraction. It was found that thermal processing considerably improves impact strength in relation to cast iron after casting. At the same time static mechanical properties are enhanced.

  2. Analyzing the mechanisms of cell killing by ionizing radiation in monolayer, spheroids and xenografted tumours

    International Nuclear Information System (INIS)

    Horas, J.A.; Olguín, O.R.; Rizzotto, M.G.

    2017-01-01

    A relationship between oxygen enhancement ratio (OER) and parameters of Linear Quadratic (LQ) model in hypoxic and aerobic conditions in several cell lines grown as monolayer, spheroids and transplanted tumors (xenograft) is tested. By considering this relationship, the two mechanisms of cell death by radiation appear. Surviving Fraction (SF) fits are compared in both oxygenation conditions by using the LQ. The data are obtained from literature. The existence of such mechanisms and their implications in the different systems studied is shown. The validity of one or other mechanism in each case is determined and the OER dependence with dose. (authors) [es

  3. A fast radio burst in the direction of the Carina dwarf spheroidal galaxy

    OpenAIRE

    Ravi, V.; Shannon, R. M.; Jameson, A.

    2014-01-01

    We report the real-time discovery of a fast radio burst (FRB 131104) with the Parkes radio telescope in a targeted observation of the Carina dwarf spheroidal galaxy. The dispersion measure of the burst is 779 cm$^{-3}$ pc, exceeding predictions for the maximum line-of-sight Galactic contribution by a factor of 11. The temporal structure of the burst is characterized by an exponential scattering tail with a timescale of 2.0$^{+0.8}_{-0.5}$ ms at 1582 MHz that scales as frequency to the power $...

  4. A novel hanging spherical drop system for the generation of cellular spheroids and high throughput combinatorial drug screening.

    Science.gov (United States)

    Neto, A I; Correia, C R; Oliveira, M B; Rial-Hermida, M I; Alvarez-Lorenzo, C; Reis, R L; Mano, J F

    2015-04-01

    We propose a novel hanging spherical drop system for anchoring arrays of droplets of cell suspension based on the use of biomimetic superhydrophobic flat substrates, with controlled positional adhesion and minimum contact with a solid substrate. By facing down the platform, it was possible to generate independent spheroid bodies in a high throughput manner, in order to mimic in vivo tumour models on the lab-on-chip scale. To validate this system for drug screening purposes, the toxicity of the anti-cancer drug doxorubicin in cell spheroids was tested and compared to cells in 2D culture. The advantages presented by this platform, such as feasibility of the system and the ability to control the size uniformity of the spheroid, emphasize its potential to be used as a new low cost toolbox for high-throughput drug screening and in cell or tissue engineering.

  5. Heterogenic expression of stem cell markers in patient-derived glioblastoma spheroid cultures exposed to long-term hypoxia

    DEFF Research Database (Denmark)

    Rosenberg, Tine; Aaberg-Jessen, Charlotte; Petterson, Stine Asferg

    2018-01-01

    AIM: To investigate the time profile of hypoxia and stem cell markers in glioblastoma spheroids of known molecular subtype. MATERIALS & METHODS: Patient-derived glioblastoma spheroids were cultured up to 7 days in either 2% or 21% oxygen. Levels of proliferation (Ki-67), hypoxia (HIF-1α, CA9...... and VEGF) and stem cell markers (CD133, nestin and musashi-1) were investigated by immunohistochemistry. RESULTS: Hypoxia markers as well as CD133 and partially nestin increased in long-term hypoxia. The proliferation rate and spheroid size were highest in normoxia. CONCLUSION: We found differences...... in hypoxia and stem cell marker profiles between the patient-derived glioblastoma cultures. This heterogeneity should be taken into consideration in development of future therapeutic strategies....

  6. Molecular and functional assessment of multicellular cancer spheroids produced in double emulsions enabled by efficient airway resistance based selective surface treatment

    Science.gov (United States)

    Ma, Xiao; Leth Jepsen, Morten; Ivarsen, Anne Kathrine R.; Knudsen, Birgitta R.; Ho, Yi-Ping

    2017-09-01

    Multicellular spheroids have garnered significant attention as an in vitro three-dimensional cancer model which can mimick the in vivo microenvironmental features. While microfluidics generated double emulsions have become a potential method to generate spheroids, challenges remain on the tedious procedures. Enabled by a novel ‘airway resistance’ based selective surface treatment, this study presents an easy and facile generation of double emulsions for the initiation and cultivation of multicellular spheroids in a scaffold-free format. Combining with our previously developed DNA nanosensors, intestinal spheroids produced in the double emulsions have shown an elevated activities of an essential DNA modifying enzyme, the topoisomerase I. The observed molecular and functional characteristics of spheroids produced in double emulsions are similar to the counterparts produced by the commercially available ultra-low attachment plates. However, the double emulsions excel for their improved uniformity, and the consistency of the results obtained by subsequent analysis of the spheroids. The presented technique is expected to ease the burden of producing spheroids and to promote the spheroids model for cancer or stem cell study.

  7. Phenotypic and microRNA transcriptomic profiling of the MDA-MB-231 spheroid-enriched CSCs with comparison of MCF-7 microRNA profiling dataset

    Directory of Open Access Journals (Sweden)

    Lily Boo

    2017-07-01

    Full Text Available Breast cancer spheroids have been widely used as in vitro models of cancer stem cells (CSCs, yet little is known about their phenotypic characteristics and microRNAs (miRNAs expression profiles. The objectives of this research were to evaluate the phenotypic characteristics of MDA-MB-231 spheroid-enriched cells for their CSCs properties and also to determine their miRNAs expression profile. Similar to our previously published MCF-7 spheroid, MDA-MB-231 spheroid also showed typical CSCs characteristics namely self-renewability, expression of putative CSCs-related surface markers and enhancement of drug resistance. From the miRNA profile, miR-15b, miR-34a, miR-148a, miR-628 and miR-196b were shown to be involved in CSCs-associated signalling pathways in both models of spheroids, which highlights the involvement of these miRNAs in maintaining the CSCs features. In addition, unique clusters of miRNAs namely miR-205, miR-181a and miR-204 were found in basal-like spheroid whereas miR-125, miR-760, miR-30c and miR-136 were identified in luminal-like spheroid. Our results highlight the roles of miRNAs as well as novel perspectives of the relevant pathways underlying spheroid-enriched CSCs in breast cancer.

  8. Comparative Analysis of 3D Bladder Tumor Spheroids Obtained by Forced Floating and Hanging Drop Methods for Drug Screening

    Directory of Open Access Journals (Sweden)

    Robson L. F. Amaral

    2017-08-01

    Full Text Available Introduction: Cell-based assays using three-dimensional (3D cell cultures may reflect the antitumor activity of compounds more accurately, since these models reproduce the tumor microenvironment better.Methods: Here, we report a comparative analysis of cell behavior in the two most widely employed methods for 3D spheroid culture, forced floating (Ultra-low Attachment, ULA, plates, and hanging drop (HD methods, using the RT4 human bladder cancer cell line as a model. The morphology parameters and growth/metabolism of the spheroids generated were first characterized, using four different cell-seeding concentrations (0.5, 1.25, 2.5, and 3.75 × 104 cells/mL, and then, subjected to drug resistance evaluation.Results: Both methods generated spheroids with a smooth surface and round shape in a spheroidization time of about 48 h, regardless of the cell-seeding concentration used. Reduced cell growth and metabolism was observed in 3D cultures compared to two-dimensional (2D cultures. The optimal range of spheroid diameter (300–500 μm was obtained using cultures initiated with 0.5 and 1.25 × 104 cells/mL for the ULA method and 2.5 and 3.75 × 104 cells/mL for the HD method. RT4 cells cultured under 3D conditions also exhibited a higher resistance to doxorubicin (IC50 of 1.00 and 0.83 μg/mL for the ULA and HD methods, respectively compared to 2D cultures (IC50 ranging from 0.39 to 0.43.Conclusions: Comparing the results, we concluded that the forced floating method using ULA plates was considered more suitable and straightforward to generate RT4 spheroids for drug screening/cytotoxicity assays. The results presented here also contribute to the improvement in the standardization of the 3D cultures required for widespread application.

  9. Comparative Analysis of 3D Bladder Tumor Spheroids Obtained by Forced Floating and Hanging Drop Methods for Drug Screening.

    Science.gov (United States)

    Amaral, Robson L F; Miranda, Mariza; Marcato, Priscyla D; Swiech, Kamilla

    2017-01-01

    Introduction: Cell-based assays using three-dimensional (3D) cell cultures may reflect the antitumor activity of compounds more accurately, since these models reproduce the tumor microenvironment better. Methods: Here, we report a comparative analysis of cell behavior in the two most widely employed methods for 3D spheroid culture, forced floating (Ultra-low Attachment, ULA, plates), and hanging drop (HD) methods, using the RT4 human bladder cancer cell line as a model. The morphology parameters and growth/metabolism of the spheroids generated were first characterized, using four different cell-seeding concentrations (0.5, 1.25, 2.5, and 3.75 × 10 4 cells/mL), and then, subjected to drug resistance evaluation. Results: Both methods generated spheroids with a smooth surface and round shape in a spheroidization time of about 48 h, regardless of the cell-seeding concentration used. Reduced cell growth and metabolism was observed in 3D cultures compared to two-dimensional (2D) cultures. The optimal range of spheroid diameter (300-500 μm) was obtained using cultures initiated with 0.5 and 1.25 × 10 4 cells/mL for the ULA method and 2.5 and 3.75 × 10 4 cells/mL for the HD method. RT4 cells cultured under 3D conditions also exhibited a higher resistance to doxorubicin (IC 50 of 1.00 and 0.83 μg/mL for the ULA and HD methods, respectively) compared to 2D cultures (IC 50 ranging from 0.39 to 0.43). Conclusions: Comparing the results, we concluded that the forced floating method using ULA plates was considered more suitable and straightforward to generate RT4 spheroids for drug screening/cytotoxicity assays. The results presented here also contribute to the improvement in the standardization of the 3D cultures required for widespread application.

  10. Modulation of Huh7.5 spheroid formation and functionality using modified PEG-based hydrogels of different stiffness.

    Directory of Open Access Journals (Sweden)

    Bae Hoon Lee

    Full Text Available Physical cues, such as cell microenvironment stiffness, are known to be important factors in modulating cellular behaviors such as differentiation, viability, and proliferation. Apart from being able to trigger these effects, mechanical stiffness tuning is a very convenient approach that could be implemented readily into smart scaffold designs. In this study, fibrinogen-modified poly(ethylene glycol-diacrylate (PEG-DA based hydrogels with tunable mechanical properties were synthesized and applied to control the spheroid formation and liver-like function of encapsulated Huh7.5 cells in an engineered, three-dimensional liver tissue model. By controlling hydrogel stiffness (0.1-6 kPa as a cue for mechanotransduction representing different stiffness of a normal liver and a diseased cirrhotic liver, spheroids ranging from 50 to 200 μm were formed over a three week time-span. Hydrogels with better compliance (i.e. lower stiffness promoted formation of larger spheroids. The highest rates of cell proliferation, albumin secretion, and CYP450 expression were all observed for spheroids in less stiff hydrogels like a normal liver in a healthy state. We also identified that the hydrogel modification by incorporation of PEGylated-fibrinogen within the hydrogel matrix enhanced cell survival and functionality possibly owing to more binding of autocrine fibronectin. Taken together, our findings establish guidelines to control the formation of Huh7.5 cell spheroids in modified PEGDA based hydrogels. These spheroids may serve as models for applications such as screening of pharmacological drug candidates.

  11. Foam shell project: Progress report

    International Nuclear Information System (INIS)

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

    1994-01-01

    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 μm thick spherical low-density foam shell surrounding a central void. The foam will be slightly overfilled with liquid D 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

  12. The evolution of mollusc shells.

    Science.gov (United States)

    McDougall, Carmel; Degnan, Bernard M

    2018-05-01

    Molluscan shells are externally fabricated by specialized epithelial cells on the dorsal mantle. Although a conserved set of regulatory genes appears to underlie specification of mantle progenitor cells, the genes that contribute to the formation of the mature shell are incredibly diverse. Recent comparative analyses of mantle transcriptomes and shell proteomes of gastropods and bivalves are consistent with shell diversity being underpinned by a rapidly evolving mantle secretome (suite of genes expressed in the mantle that encode secreted proteins) that is the product of (a) high rates of gene co-option into and loss from the mantle gene regulatory network, and (b) the rapid evolution of coding sequences, particular those encoding repetitive low complexity domains. Outside a few conserved genes, such as carbonic anhydrase, a so-called "biomineralization toolkit" has yet to be discovered. Despite this, a common suite of protein domains, which are often associated with the extracellular matrix and immunity, appear to have been independently and often uniquely co-opted into the mantle secretomes of different species. The evolvability of the mantle secretome provides a molecular explanation for the evolution and diversity of molluscan shells. These genomic processes are likely to underlie the evolution of other animal biominerals, including coral and echinoderm skeletons. This article is categorized under: Comparative Development and Evolution > Regulation of Organ Diversity Comparative Development and Evolution > Evolutionary Novelties. © 2018 Wiley Periodicals, Inc.

  13. Creep buckling of shell structures

    International Nuclear Information System (INIS)

    Miyazaki, Noriyuki; Hagihara, Seiya

    2015-01-01

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

  14. Core-Shell-Corona Micelles with a Responsive Shell.

    Science.gov (United States)

    Gohy, Jean-François; Willet, Nicolas; Varshney, Sunil; Zhang, Jian-Xin; Jérôme, Robert

    2001-09-03

    A reactor for the synthesis of gold nanoparticles is one of the uses of a poly(styrene)-block-poly(2-vinylpyridine)-block-poly(ethylene oxide) triblock copolymer (PS-b-P2VP-b-PEO) which forms core-shell-corona micelles in water. Very low polydispersity spherical micelles are observed that consist of a PS core surrounded by a pH-sensitive P2VP shell and a corona of PEO chains end-capped by a hydroxyl group. The corona can act as a site for attaching responsive or sensing molecules. © 2001 WILEY-VCH Verlag GmbH, Weinheim, Fed. Rep. of Germany.

  15. A three-dimensional in vitro HepG2 cells liver spheroid model for genotoxicity studies.

    Science.gov (United States)

    Shah, Ume-Kulsoom; Mallia, Jefferson de Oliveira; Singh, Neenu; Chapman, Katherine E; Doak, Shareen H; Jenkins, Gareth J S

    2018-01-01

    The liver's role in metabolism of chemicals makes it an appropriate tissue for toxicity testing. Current testing protocols, such as animal testing and two-dimensional liver cell systems, offer limited resemblance to in vivo liver cell behaviour, in terms of gene expression profiles and metabolic competence; thus, they do not always accurately predict human toxicology. In vitro three-dimensional liver cell models offer an attractive alternative. This study reports on the development of a 3D liver model, using HepG2 cells, by a hanging-drop technique, with a focus on evaluating spheroid growth characteristics and suitability for genotoxicity testing. The cytokinesis-blocked micronucleus assay protocol was adapted to enable micronucleus (MN) detection in the 3D spheroid models. This involved evaluating the difference between hanging vs non-hanging drop positions for dosing of the test agents and comparison of automated Metafer scoring with manual scoring for MN detection in HepG2 spheroids. The initial seeding density, used for all experiments, was 5000 cells/20 μl drop hanging spheroids, harvested on day 4, with >75% cell viability. Albumin secretion (7.8 g/l) and both CYP1A1 and CYP1A2 gene expression were highest in the 3D environment at day 4. Exposure to metabolically activated genotoxicants for 24 h resulted in a 6-fold increase in CYP1A1 enzyme activity (3 μM B[a]P) and a 30-fold increase in CYP1A2 enzyme activity (5 μM PhIP) in 3D hanging spheroids. MN inductions in response to B[a]P or PhIP were 2-fold and 3-fold, respectively, and were greater in 3D hanging spheroids than in 2D format, showing that hanging spheroids are more sensitive to genotoxic agents. HepG2 hanging-drop spheroids are an exciting new alternative system for genotoxicity studies, due to their improved structural and physiological properties, relative to 2D cultures. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Shape dependency of the extinction and absorption cross sections of dust aerosols modeled as randomly oriented spheroids

    Directory of Open Access Journals (Sweden)

    R. Wagner

    2011-09-01

    Full Text Available We present computational results on the shape dependency of the extinction and absorption cross sections of dustlike aerosol particles that were modeled as randomly oriented spheroids. Shape dependent variations in the extinction cross sections are largest in the size regime that is governed by the interference structure. Elongated spheroids best fitted measured extinction spectra of re-dispersed Saharan dust samples. For dust particles smaller than 1.5 μm in diameter and low absorption potential, shape effects on the absorption cross sections are very small.

  17. Imaging- and Flow Cytometry-based Analysis of Cell Position and the Cell Cycle in 3D Melanoma Spheroids

    OpenAIRE

    Beaumont, Kimberley A.; Anfosso, Andrea; Ahmed, Farzana; Weninger, Wolfgang; Haass, Nikolas K.

    2015-01-01

    Three-dimensional (3D) tumor spheroids are utilized in cancer research as a more accurate model of the in vivo tumor microenvironment, compared to traditional two-dimensional (2D) cell culture. The spheroid model is able to mimic the effects of cell-cell interaction, hypoxia and nutrient deprivation, and drug penetration. One characteristic of this model is the development of a necrotic core, surrounded by a ring of G1 arrested cells, with proliferating cells on the outer layers of the sphero...

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

    Science.gov (United States)

    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. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. Towards personalized computational oncology: from spatial models of tumour spheroids, to organoids, to tissues.

    Science.gov (United States)

    Karolak, Aleksandra; Markov, Dmitry A; McCawley, Lisa J; Rejniak, Katarzyna A

    2018-01-01

    A main goal of mathematical and computational oncology is to develop quantitative tools to determine the most effective therapies for each individual patient. This involves predicting the right drug to be administered at the right time and at the right dose. Such an approach is known as precision medicine. Mathematical modelling can play an invaluable role in the development of such therapeutic strategies, since it allows for relatively fast, efficient and inexpensive simulations of a large number of treatment schedules in order to find the most effective. This review is a survey of mathematical models that explicitly take into account the spatial architecture of three-dimensional tumours and address tumour development, progression and response to treatments. In particular, we discuss models of epithelial acini, multicellular spheroids, normal and tumour spheroids and organoids, and multi-component tissues. Our intent is to showcase how these in silico models can be applied to patient-specific data to assess which therapeutic strategies will be the most efficient. We also present the concept of virtual clinical trials that integrate standard-of-care patient data, medical imaging, organ-on-chip experiments and computational models to determine personalized medical treatment strategies. © 2018 The Author(s).

  20. High-throughput 3D spheroid culture and drug testing using a 384 hanging drop array.

    Science.gov (United States)

    Tung, Yi-Chung; Hsiao, Amy Y; Allen, Steven G; Torisawa, Yu-suke; Ho, Mitchell; Takayama, Shuichi

    2011-02-07

    Culture of cells as three-dimensional (3D) aggregates can enhance in vitro tests for basic biological research as well as for therapeutics development. Such 3D culture models, however, are often more complicated, cumbersome, and expensive than two-dimensional (2D) cultures. This paper describes a 384-well format hanging drop culture plate that makes spheroid formation, culture, and subsequent drug testing on the obtained 3D cellular constructs as straightforward to perform and adapt to existing high-throughput screening (HTS) instruments as conventional 2D cultures. Using this platform, we show that drugs with different modes of action produce distinct responses in the physiological 3D cell spheroids compared to conventional 2D cell monolayers. Specifically, the anticancer drug 5-fluorouracil (5-FU) has higher anti-proliferative effects on 2D cultures whereas the hypoxia activated drug commonly referred to as tirapazamine (TPZ) are more effective against 3D cultures. The multiplexed 3D hanging drop culture and testing plate provides an efficient way to obtain biological insights that are often lost in 2D platforms.

  1. FEATURES OF SPHEROIDIZING MODIFICATION OF HIGH-STRENGTH CAST IRON WITH MASTER ALLOYS BASED ON COPPER

    Directory of Open Access Journals (Sweden)

    A. S. Kalinichenko

    2016-01-01

    Full Text Available The increase of efficiency of modification process for ductile iron is topically, thereby increasing its mechanical and operational properties. For these purposes, in practice, various magnesium containing alloys are used, including «heavy» ones on the basis of Copper and Nickel. The analysis has shown that the application of bulk inoculating alloys based on copper basis were not effectively due to long dissolution period. From this point of view, the interest is high-speed casting, allowing the production of inoculating alloys in the form of strips – chips that are characterized by a low dissolution time and low piroeffekt. The aim of this work is to study the features of structure formation in nodular cast iron using different spheroidizing alloys based on copper. Studies have shown that the transition from the use of briquetted form alloys based on copper and magnesium to the «chips-inoculating alloys» allowed increasing the efficiency of the spheroidizing process. Further improvement in the quality of ductile iron can be achieved by the use in «chip-inoculating alloys» additives of nanosized yttrium oxide powder. 

  2. Simulation for light extraction efficiency of OLEDs with spheroidal microlenses in hexagonal array

    Science.gov (United States)

    Bae, Hyungchul; Kim, Jun Soo; Hong, Chinsoo

    2018-05-01

    A theoretical model based on ray optics is used to simulate the optical performance of organic light-emitting diodes (OLEDs) with spheroidal microlens arrays (MLAs) in a hexagonal array configuration using the Monte Carlo method. In simulations, ray tracing was performed until 20 reflections occurred from the metal cathode, with 10 consecutive reflections permitted in a single lens pattern. The parameters describing the shape and array of the lens pattern of a MLA are its radius, height, contact angle, and fill factor (FF). Many previous results on how these parameters affect light extraction efficiency (LEE) are inconsistent. In this paper, these contradictory results are discussed and explained by introducing a new parameter. To examine light extraction from an OLED through a MLA, the LEE enhancement is studied considering the effect of absorption by indium tin oxide during multiple reflections from the metal cathode. The device size where LEE enhancement is unchanged with changing lens pattern was identified for a fixed FF; under this condition, the optimal LEE enhancement, 84%, can be obtained using an OLED with a close-packed spheroidal MLA. An ideal maximum LEE enhancement of 120% was achieved with a device with an infinite-sized MLA. The angular intensity distribution of light emitted through a MLA is considered in addition to LEE enhancement for an optimized MLA.

  3. Theoretical analysis on radiation and reception characteristics of an oblate spheroidal antenna for electron plasma waves

    International Nuclear Information System (INIS)

    Ohnuki, S.; Adachi, S.; Ohnuma, T.

    1978-01-01

    The radiation and reception characteristics of the oblate spheroidal antenna for electron plasma waves are theoretically investigated. The analysis is carried out as a boundary-value problem. The formulas for the radiation and reception characteristics such as radiation impedance, electron charge distributions, radiated wave potential, directional properties, and receiving voltage of the oblate spheroidal antenna are analytically obtained. As a result, it is concluded that the radiation and reception characteristics of the antennas are not uniquely determined by k/sub p/a (k/sub p/ is the wave number of an electron plasma wave, and a is the radius of the circular-plate antenna), but are determined by two out of three factors, k/sub p/a, zeta (radius divided by Debye length), and ω/ω/sub p/ (angular signal frequency to angular plasma frequency). This conclusion is in marked contrast to the conventional theory in which the charge distribution on the antenna is assumed a priori as uniform and, thus, the antenna characteristics are uniquely determined by k/sub p/a. It is claimed that the experimental results obtained hitherto support the present new theory

  4. FORMATION OF MASSIVE GALAXIES AT HIGH REDSHIFT: COLD STREAMS, CLUMPY DISKS, AND COMPACT SPHEROIDS

    International Nuclear Information System (INIS)

    Dekel, Avishai; Sari, Re'em; Ceverino, Daniel

    2009-01-01

    We present a simple theoretical framework for massive galaxies at high redshift, where the main assembly and star formation occurred, and report on the first cosmological simulations that reveal clumpy disks consistent with our analysis. The evolution is governed by the interplay between smooth and clumpy cold streams, disk instability, and bulge formation. Intense, relatively smooth streams maintain an unstable dense gas-rich disk. Instability with high turbulence and giant clumps, each a few percent of the disk mass, is self-regulated by gravitational interactions within the disk. The clumps migrate into a bulge in ∼ sun yr -1 , and each clump converts into stars in ∼0.5 Gyr. While the clumps coalesce dissipatively to a compact bulge, the star-forming disk is extended because the incoming streams keep the outer disk dense and susceptible to instability and because of angular momentum transport. Passive spheroid-dominated galaxies form when the streams are more clumpy: the external clumps merge into a massive bulge and stir up disk turbulence that stabilize the disk and suppress in situ clump and star formation. We predict a bimodality in galaxy type by z ∼ 3, involving giant-clump star-forming disks and spheroid-dominated galaxies of suppressed star formation. After z ∼ 1, the disks tend to be stabilized by the dominant stellar disks and bulges. Most of the high-z massive disks are likely to end up as today's early-type galaxies.

  5. Phenotypic feature quantification of patient derived 3D cancer spheroids in fluorescence microscopy image

    Science.gov (United States)

    Kang, Mi-Sun; Rhee, Seon-Min; Seo, Ji-Hyun; Kim, Myoung-Hee

    2017-03-01

    Patients' responses to a drug differ at the cellular level. Here, we present an image-based cell phenotypic feature quantification method for predicting the responses of patient-derived glioblastoma cells to a particular drug. We used high-content imaging to understand the features of patient-derived cancer cells. A 3D spheroid culture formation resembles the in vivo environment more closely than 2D adherent cultures do, and it allows for the observation of cellular aggregate characteristics. However, cell analysis at the individual level is more challenging. In this paper, we demonstrate image-based phenotypic screening of the nuclei of patient-derived cancer cells. We first stitched the images of each well of the 384-well plate with the same state. We then used intensity information to detect the colonies. The nuclear intensity and morphological characteristics were used for the segmentation of individual nuclei. Next, we calculated the position of each nucleus that is appeal of the spatial pattern of cells in the well environment. Finally, we compared the results obtained using 3D spheroid culture cells with those obtained using 2D adherent culture cells from the same patient being treated with the same drugs. This technique could be applied for image-based phenotypic screening of cells to determine the patient's response to the drug.

  6. Automated imaging of cellular spheroids with selective plane illumination microscopy on a chip (Conference Presentation)

    Science.gov (United States)

    Paiè, Petra; Bassi, Andrea; Bragheri, Francesca; Osellame, Roberto

    2017-02-01

    Selective plane illumination microscopy (SPIM) is an optical sectioning technique that allows imaging of biological samples at high spatio-temporal resolution. Standard SPIM devices require dedicated set-ups, complex sample preparation and accurate system alignment, thus limiting the automation of the technique, its accessibility and throughput. We present a millimeter-scaled optofluidic device that incorporates selective plane illumination and fully automatic sample delivery and scanning. To this end an integrated cylindrical lens and a three-dimensional fluidic network were fabricated by femtosecond laser micromachining into a single glass chip. This device can upgrade any standard fluorescence microscope to a SPIM system. We used SPIM on a CHIP to automatically scan biological samples under a conventional microscope, without the need of any motorized stage: tissue spheroids expressing fluorescent proteins were flowed in the microchannel at constant speed and their sections were acquired while passing through the light sheet. We demonstrate high-throughput imaging of the entire sample volume (with a rate of 30 samples/min), segmentation and quantification in thick (100-300 μm diameter) cellular spheroids. This optofluidic device gives access to SPIM analyses to non-expert end-users, opening the way to automatic and fast screening of a high number of samples at subcellular resolution.

  7. Enlarging the nosological spectrum of hereditary diffuse leukoencephalopathy with axonal spheroids (HDLS).

    Science.gov (United States)

    Hoffmann, Sarah; Murrell, Jill; Harms, Lutz; Miller, Kelly; Meisel, Andreas; Brosch, Thomas; Scheel, Michael; Ghetti, Bernardino; Goebel, Hans-Hilmar; Stenzel, Werner

    2014-09-01

    Hereditary diffuse leukoencephalopathy with axonal spheroids (HDLS) is an autosomal dominant disease clinically characterized by cognitive decline, personality changes, motor impairment, parkinsonism and seizures. Recently, mutations in the colony-stimulating factor-1 receptor (CSF1R) gene have been shown to be associated with HDLS. We report clinical, neuropathological and molecular genetic findings of patients from a new family with a mutation in the CSF1R gene. Disease onset was earlier and disease progression was more rapid compared with previously reported patients. Psychiatric symptoms including personality changes, alcohol abuse and severe depression were the first symptoms in male patients. In the index, female patient, the initial symptom was cognitive decline. Magnetic resonance imaging (MRI) showed bilateral, confluent white matter lesions in the cerebrum. Stereotactic biopsy revealed loss of myelin and microglial activation as well as macrophage infiltration of the parenchyma. Numerous axonal swellings and spheroids were present. Ultrastructural analysis revealed pigment-containing macrophages. Axonal swellings were detected by electron microscopy not only in the central nervous system (CNS) but also in skin nerves. We identified a heterozygous mutation (c.2330G>A, p.R777Q) in the CSF1R gene. Through this report, we aim to enlarge the nosological spectrum of HDLS, providing new clinical descriptions as well as novel neuropathological findings from the peripheral nervous system. © 2014 International Society of Neuropathology.

  8. Theory of a spheroidal probe in low-density continuum plasmas

    International Nuclear Information System (INIS)

    Kamitsuma, M.; Teii, S.

    1982-01-01

    A spheroidal probe theory for a low-density continuum plasma, i.e., one where the electron density is N/sub e/ 8 cm -3 and the gas pressure is P> or approx. =1 Torr has been developed using a spheroidal coordinate system in order to properly take into account the effect of the finite length of the probe. The numerical results of both the electron- and the ion-current characteristics are obtained for various values of R/sub p//lambda/sub D/ ranging from 0 to 1, epsilon = T/sub i//T/sub e/ from 0.1 to 1, and C/sub p/ = L/sub p//2R/sub p/ from 1 to 100, where lambda/sub D/ is the Debye length, R/sub p/ and L/sub p/ are the probe radius and the probe length, T/sub i/ and T/sub e/ are the ion and the electron temperature, respectively. Using these results, new methods to determine the electron temperature and the plasma space potential (consequently, the electron density) by practical measurements are also proposed and discussed

  9. Spheroidization by Plasma Processing and Characterization of Stainless Steel Powder for 3D Printing

    Science.gov (United States)

    Ji, Lina; Wang, Changzhen; Wu, Wenjie; Tan, Chao; Wang, Guoyu; Duan, Xuan-Ming

    2017-10-01

    Stainless steel 316L (SS 316L) powder was spheroidized by plasma processing to improve its suitability for powder 3D printing. The obtained spheroidized (sphero) powder was characterized in terms of its crystalline phases, elemental composition, morphology, particle size and distribution, light absorption, and flow properties. The elemental composition of the sphero powder met the Chinese standard for SS 316L except for its Si content. The volume fraction of ferrite increased after plasma processing. Furthermore, plasma processing was shown to not only reduce the mean size of the particles in the size range of 10 to 100 μm but also generate particles in the size range of 0.1 to 10 μm. The smaller particles filled the voids among larger particles, increasing the powder density. The light absorption was also increased owing to enhanced internal reflection. Although the basic flow energy decreased after plasma processing, the flow function (FF) value was smaller for the sphero powder, indicating a lower flowability of the sphero powder. However, the density of SS 316L pieces printed with commercial and sphero powders was 98.76 pct and 98.16 pct of the SS 316L bulk density, respectively, indicating the suitability of the sphero powder for 3D printing despite an FF below 10.

  10. Shell model Monte Carlo methods

    International Nuclear Information System (INIS)

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

    1997-01-01

    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; the resultant path integral is evaluated stochastically. We first discuss the motivation, formalism, and implementation of such Shell Model Monte Carlo (SMMC) 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, the thermal and rotational behavior of rare-earth and γ-soft nuclei, and the calculation of double beta-decay matrix elements. Finally, prospects for further progress in such calculations are discussed. (orig.)

  11. Cask for concrete shells transportation

    International Nuclear Information System (INIS)

    Labergri, F.

    2001-01-01

    Nowadays, nuclear plant radioactive waste are conditioned in situ into concrete shells. Most of them enter in the industrial waste category defined by the regulations of radioactive material transportation. However, the content of a few ones exceeds the limits set for low specific activity substances. Thus, these shells must be transported into type B packagings. To this end, Robatel has undertaken, for EDF (Electricite de France), the development of a container, named ROBATEL TM R68, for further licensing. The particularity of this packaging is that the lid must have a wide opening to allow the usual handling operations of the concrete shells. This leads to a non-conventional conception, and makes the package more vulnerable to drop test solicitations. In order to define a minimal drop test program on a reduced scale model, we use a simple method to find the most damageable drop angle. (author)

  12. Shell model Monte Carlo methods

    International Nuclear Information System (INIS)

    Koonin, S.E.

    1996-01-01

    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 γ-soft nuclei, and calculation of double beta-decay matrix elements. Finally, prospects for further progress in such calculations are discussed. 87 refs

  13. Windows PowerShell 20 Bible

    CERN Document Server

    Lee, Thomas; Schill, Mark E; Tanasovski, Tome

    2011-01-01

    Here's the complete guide to Windows PowerShell 2.0 for administrators and developers Windows PowerShell is Microsoft's next-generation scripting and automation language. This comprehensive volume provides the background that IT administrators and developers need in order to start using PowerShell automation in exciting new ways. It explains what PowerShell is, how to use the language, and specific ways to apply PowerShell in various technologies. Windows PowerShell is Microsoft's standard automation tool and something that every Windows administrator will eventually have to understand; this b

  14. Learning Shell scripting with Zsh

    CERN Document Server

    Festari, Gaston

    2014-01-01

    A step-by-step tutorial that will teach you, through real-world examples, how to configure and use Zsh and its various features. If you are a system administrator, developer, or computer professional involved with UNIX who are looking to improve on their daily tasks involving the UNIX shell, ""Learning Shell Scripting with Zsh"" will be great for you. It's assumed that you have some familiarity with an UNIX command-line interface and feel comfortable with editors such as Emacs or vi.

  15. Isogeometric shell formulation based on a classical shell model

    KAUST Repository

    Niemi, Antti; Collier, Nathan; Dalcí n, Lisandro D.; Ghommem, Mehdi; Calo, Victor M.

    2012-01-01

    The authors future work is concerned with building an isogeometric finite element method for modelling nonlinear structural response of thin-walled shells undergoing large rigid-body motions. The aim is to use the model in a aeroelastic framework for the simulation of flapping wings.

  16. Activated carbons prepared from hazelnut shells, walnut shells and peanut shells for high CO2 adsorption

    Directory of Open Access Journals (Sweden)

    Lewicka Katarzyna

    2017-06-01

    Full Text Available Research treats about producing activated carbons for CO2 capture from hazelnut shells (HN, walnut shells (WN and peanut shells (PN. Saturated solution of KOH was used as an activating agent in ratio 1:1. Samples were carbonized in the furnace in the range of temperatures 600°C–900°C. Properties of carbons were tested by N2 adsorption method, using BET equation, DFT method and volumetric CO2 adsorption method. With the increase of carbonization temperature specific surface area of studied samples increased. The largest surface area was calculated for samples carbonized at 900°C and the highest values of CO2 adsorption had samples: PN900 at 0°C (5.5 mmol/g and WN900 at 25°C (4.34 mmol/g. All of the samples had a well-developed microporous structure.

  17. Indentation of Ellipsoidal and Cylindrical Elastic Shells

    KAUST Repository

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

    2012-01-01

    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

  18. Adaptative mixed methods to axisymmetric shells

    International Nuclear Information System (INIS)

    Malta, S.M.C.; Loula, A.F.D.; Garcia, E.L.M.

    1989-09-01

    The mixed Petrov-Galerkin method is applied to axisymmetric shells with uniform and non uniform meshes. Numerical experiments with a cylindrical shell showed a significant improvement in convergence and accuracy with adaptive meshes. (A.C.A.S.) [pt

  19. Tube in shell heat exchangers

    International Nuclear Information System (INIS)

    Hayden, O.; Willby, C.R.; Sheward, G.E.; Ormrod, D.T.; Firth, G.F.

    1980-01-01

    An improved tube-in-shell heat exchanger to be used between liquid metal and water is described for use in the liquid metal coolant system of fast breeder reactors. It is stated that this design is less prone to failures which could result in sodium water reactions than previous exchangers. (UK)

  20. Shell theorem for spontaneous emission

    DEFF Research Database (Denmark)

    Kristensen, Philip Trøst; Mortensen, Jakob Egeberg; Lodahl, Peter

    2013-01-01

    and therefore is given exactly by the dipole approximation theory. This surprising result is a spontaneous emission counterpart to the shell theorems of classical mechanics and electrostatics and provides insights into the physics of mesoscopic emitters as well as great simplifications in practical calculations....

  1. Nonlinear theory of elastic shells

    International Nuclear Information System (INIS)

    Costa Junior, J.A.

    1979-08-01

    Nonlinear theory of elastic shells is developed which incorporates both geometric and physical nonlinearities and which does not make use of the well known Love-Kirchhoff hypothesis. The resulting equations are formulated in tensorial notation and are reduced to the ones of common use when simplifying assumptions encountered in the especific litterature are taken. (Author) [pt

  2. Shell energy scenarios to 2050

    International Nuclear Information System (INIS)

    2008-01-01

    Shell developed two scenarios that describe alternative ways the energy future may develop. In the first scenario (Scramble) policymakers pay little attention to more efficient energy use until supplies are tight. Likewise, greenhouse gas emissions are not seriously addressed until there are major climate shocks. In the second scenario (Blueprints) growing local actions begin to address the challenges of economic development, energy security and environmental pollution. A price is applied to a critical mass of emissions giving a huge stimulus to the development of clean energy technologies, such as carbon dioxide capture and storage, and energy efficiency measures. The result is far lower carbon dioxide emissions. Both these scenarios can help Shell to test their strategy against a range of possible developments over the long-term. However, according to Shell, the Blueprints' outcomes offer the best hope for a sustainable future, whether or not they arise exactly in the way described. However, with the right combination of policy, technology and commitment from governments, industry and society globally, Shell believes it can be realized. But achieving the targets will not be easy, and time is short. Clear thinking, huge investment, and effective leadership are required

  3. Collapse analysis of toroidal shell

    International Nuclear Information System (INIS)

    Pomares, R.J.

    1990-01-01

    This paper describes a study performed to determine the collapse characteristics of a toroidal shell using finite element method (FEM) analysis. The study also included free drop testing of a quarter scale prototype to verify the analytical results. The full sized toroidal shell has a 24-inch toroidal diameter with a 24-inch tubal diameter. The shell material is type 304 strainless steel. The toroidal shell is part of the GE Model 2000 transportation packaging, and acts as an energy absorbing device. The analyses performed were on a full sized and quarter scaled models. The finite element program used in all analyses was the LIBRA code. The analytical procedure used both the elasto-plastic and large displacement options within the code. The loading applied in the analyses corresponded to an impact of an infinite rigid plane oriented normal to the drop direction vector. The application of the loading continued incrementally until the work performed by the deforming structure equalled the kinetic energy developed in the free fall. The comparison of analysis and test results showed a good correlation

  4. Effects of hypoxia on expression of a panel of stem cell and chemoresistance markers in glioblastoma-derived spheroids

    DEFF Research Database (Denmark)

    Kolenda, Jesper; Jensen, Stine Skov; Aaberg-Jessen, Charlotte

    2011-01-01

    ). Spheroids were formed in 21% and 1% O(2) in serum-free medium. The immunohistochemical panel included hypoxia (HIF-1α, HIF-2α), proliferation (Ki-67), and stem cell markers (CD133, podoplanin, Bmi-1, nestin, Sox-2) as well as markers related to chemoresistance (MGMT, TIMP-1, Lamp-1, MRP1, MDR-1...

  5. High resolution spectroscopy of Red Giant Branch stars and the chemical evolution of the Fornax dwarf spheroidal galaxy

    NARCIS (Netherlands)

    Lemasle, B.; de Boer, T. J. L.; Hill, V.; Tolstoy, E.; Irwin, M. J.; Jablonka, P.; Venn, K.; Battaglia, G.; Starkenburg, E.; Shetrone, M.; Letarte, B.; Francois, P.; Helmi, A.; Primas, F.; Kaufer, A.; Szeifert, T.; Ballet, J.; Martins, F.; Bournaud, F.; Monier, R.; Reylé, C.

    2014-01-01

    From VLT-FLAMES high-resolution spectra, we determine the abundances of several α, iron-peak and neutron-capture elements in 47 Red Giant Branch stars in the Fornax dwarf spheroidal galaxy. We confirm that SNe Ia started to contribute to the chemical enrichment of Fornax at [Fe/H] between --2.0 and

  6. A high-resolution VLT/FLAMES study of individual stars in the centre of the Fornax dwarf spheroidal galaxy

    NARCIS (Netherlands)

    Letarte, B.; Hill, V.; Tolstoy, E.; Jablonka, P.; Shetrone, M.; Venn, K. A.; Spite, M.; Irwin, M. J.; Battaglia, G.; Helmi, A.; Primas, F.; François, P.; Kaufer, A.; Szeifert, T.; Arimoto, N.; Sadakane, K.

    2010-01-01

    For the first time we show the detailed, late-stage, chemical evolution history of a small nearby dwarf spheroidal galaxy in the Local Group. We present the results of a high-resolution (R similar to 20 000, lambda = 5340-5620; 6120-6701) FLAMES/GIRAFFE abundance study at ESO/VLT of 81

  7. The ACS LCID project : RR Lyrae stars as tracers of old population gradients in the isolated dwarf spheroidal galaxy tucana

    NARCIS (Netherlands)

    Bernard, Edouard J.; Gallart, Carme; Monelli, Matteo; Aparicio, Antonio; Cassisi, Santi; Skillman, Evan D.; Stetson, Peter B.; Cole, Andrew A.; Drozdovsky, Igor; Hidalgo, Sebastian L.; Mateo, Mario; Tolstoy, Eline

    2008-01-01

    We present a study of the radial distribution of RR Lyrae variables, which present a range of photometric and pulsational properties, in the dwarf spheroidal galaxy Tucana. We find that the fainter RR Lyrae stars, having a shorter period, are more centrally concentrated than the more luminous,

  8. Two distinct ancient components in the Sculptor dwarf spheroidal galaxy : First results from the dwarf abundances and radial velocities team

    NARCIS (Netherlands)

    Tolstoy, E; Irwin, MJ; Helmi, A; Battaglia, G; Jablonka, P; Hill, [No Value; Venn, KA; Shetrone, MD; Letarte, B; Cole, AA; Primas, F; Francois, P; Arimoto, N; Sadakane, K; Kaufer, A; Szeifert, T; Abel, T

    2004-01-01

    We have found evidence for the presence of two distinct ancient stellar components (bothgreater than or equal to10 Gyr old) in the Sculptor dwarf spheroidal galaxy. We used the ESO Wide Field Imager in conjunction with the Very Large Telescope/FLAMES spectrograph to study the properties of the

  9. VLT/UVES spectroscopy of individual stars in three globular clusters in the Fornax dwarf spheroidal galaxy

    NARCIS (Netherlands)

    Letarte, B; Hill, [No Value; Jablonka, P; Tolstoy, E; Francois, P; Meylan, G

    We present a high resolution ( R similar to 43 000) abundance analysis of a total of nine stars in three of the five globular clusters associated with the nearby Fornax dwarf spheroidal galaxy. These three clusters ( 1, 2 and 3) trace the oldest, most metal-poor stellar populations in Fornax. We

  10. 384 hanging drop arrays give excellent Z-factors and allow versatile formation of co-culture spheroids.

    Science.gov (United States)

    Hsiao, Amy Y; Tung, Yi-Chung; Qu, Xianggui; Patel, Lalit R; Pienta, Kenneth J; Takayama, Shuichi

    2012-05-01

    We previously reported the development of a simple, user-friendly, and versatile 384 hanging drop array plate for 3D spheroid culture and the importance of utilizing 3D cellular models in anti-cancer drug sensitivity testing. The 384 hanging drop array plate allows for high-throughput capabilities and offers significant improvements over existing 3D spheroid culture methods. To allow for practical 3D cell-based high-throughput screening and enable broader use of the plate, we characterize the robustness of the 384 hanging drop array plate in terms of assay performance and demonstrate the versatility of the plate. We find that the 384 hanging drop array plate performance is robust in fluorescence- and colorimetric-based assays through Z-factor calculations. Finally, we demonstrate different plate capabilities and applications, including: spheroid transfer and retrieval for Janus spheroid formation, sequential addition of cells for concentric layer patterning of different cell types, and culture of a wide variety of cell types. Copyright © 2011 Wiley Periodicals, Inc.

  11. Three-dimensional spheroid culture targeting versatile tissue bioassays using a PDMS-based hanging drop array.

    Science.gov (United States)

    Kuo, Ching-Te; Wang, Jong-Yueh; Lin, Yu-Fen; Wo, Andrew M; Chen, Benjamin P C; Lee, Hsinyu

    2017-06-29

    Biomaterial-based tissue culture platforms have emerged as useful tools to mimic in vivo physiological microenvironments in experimental cell biology and clinical studies. We describe herein a three-dimensional (3D) tissue culture platform using a polydimethylsiloxane (PDMS)-based hanging drop array (PDMS-HDA) methodology. Multicellular spheroids can be achieved within 24 h and further boosted by incorporating collagen fibrils in PDMS-HDA. In addition, the spheroids generated from different human tumor cells exhibited distinct sensitivities toward drug chemotherapeutic agents and radiation as compared with two-dimensional (2D) cultures that often lack in vivo-like biological insights. We also demonstrated that multicellular spheroids may enable key hallmarks of tissue-based bioassays, including drug screening, tumor dissemination, cell co-culture, and tumor invasion. Taken together, these results offer new opportunities not only to achieve the active control of 3D multicellular spheroids on demand, but also to establish a rapid and cost-effective platform to study anti-cancer therapeutics and tumor microenvironments.

  12. The role of Rad 51 protein in radioresistance of spheroid model of Du 145 prostate carcinoma cell line

    International Nuclear Information System (INIS)

    Taghizadeh, M.; Khoei, S.; Nikoofar, A. R.; Ghamsari, L.; Goliaei, B.

    2009-01-01

    Rad 51 is a protein with critical role in double strand break repair. Down-regulation of this protein has a significant effect in radiosensitivity of some cell lines like prostate carcinoma. Compared to monolayer cell culture model, the spheroids are more resistant to radiation. The aim of the current study was to determine the Rad 51 protein level in Du 145 spheroids, and monolayer cells before and after exposure to gamma irradiation. Materials and Methods: In the present study, western blot was used to determine the level of Rad 51 protein in Du 145 cell line grown as monolayer and spheroid. Results: Western blot analysis showed that in the spheroid cells, Rad 51 had an elevated level before and after radiation in comparison with monolayer cells. Higher doses of radiation induced elevated expression of Rad 51 protein in both culture models.The level of at protein after exposure to gamma rays had been time-dependent. Conclusion: Rad 51 might act as a mediator of radiation resistance in tumor cells. Repression of Rad 51 activity could be a prominent strategy to overcome radiation resistance of tumors.

  13. Stellar Kinematics and Metallicities in the Draco and Ursa Minor Dwarf Spheroidal Galaxies from WHT/AF2-WYFFOS

    NARCIS (Netherlands)

    Jin, S.; Irwin, M.; Tolstoy, E.; Lewis, J.; Hartke, J.; Skillen, I.; Barcells, M.; Trager, S.

    2016-01-01

    We present preliminary results from our chemo-dynamical survey of two Milky Way dwarf spheroidal (dSph) galaxies, Draco and Ursa Minor. The two galaxies have similar radial velocities and reside in close proximity in the outskirts of the Milky Way halo, yet exhibit noteworthy differences in their

  14. Cell cycle variation in x-ray survival for cells from spheroids measured by volume cell sorting

    International Nuclear Information System (INIS)

    Freyer, J.P.; Wilder, M.E.; Raju, M.R.

    1984-01-01

    Considerable work has been done studying the variation in cell survival as a function of cell cycle position for monolayers or single cells exposed to radiation. Little is known about the effects of multicellular growth on the relative radiation sensitivity of cells in different cell cycle stages. The authors have developed a new technique for measuring the response of cells, using volume cell sorting, which is rapid, non-toxic, and does not require cell synchronization. By combining this technique with selective spheroid dissociation,they have measured the age response of cells located at various depths in EMT6 and Colon 26 spheroids. Although cells in the inner region had mostly G1-phase DNA contents, 15-20% had S- and G2-phase DNA contents. Analysis of these cells using BrdU labeling and flow cytometric analysis with a monoclonal antibody to BrdU indicated that the inner region cells were not synthesizing DNA. Thus, the authors were able to measure the radiation response of cells arrested in G1, S and G2 cell cycle phases. Comparison of inner and outer spheroid regions, and monolayer cultures, indicates that it is improper to extrapolate age response data in standard culture conditions to the situation in spheroids

  15. Bioprinting-Based High-Throughput Fabrication of Three-Dimensional MCF-7 Human Breast Cancer Cellular Spheroids

    Directory of Open Access Journals (Sweden)

    Kai Ling

    2015-06-01

    Full Text Available Cellular spheroids serving as three-dimensional (3D in vitro tissue models have attracted increasing interest for pathological study and drug-screening applications. Various methods, including microwells in particular, have been developed for engineering cellular spheroids. However, these methods usually suffer from either destructive molding operations or cell loss and non-uniform cell distribution among the wells due to two-step molding and cell seeding. We have developed a facile method that utilizes cell-embedded hydrogel arrays as templates for concave well fabrication and in situ MCF-7 cellular spheroid formation on a chip. A custom-built bioprinting system was applied for the fabrication of sacrificial gelatin arrays and sequentially concave wells in a high-throughput, flexible, and controlled manner. The ability to achieve in situ cell seeding for cellular spheroid construction was demonstrated with the advantage of uniform cell seeding and the potential for programmed fabrication of tissue models on chips. The developed method holds great potential for applications in tissue engineering, regenerative medicine, and drug screening.

  16. On the surviving fraction in irradiated multicellular tumour spheroids: calculation of overall radiosensitivity parameters, influence of hypoxia and volume effects

    International Nuclear Information System (INIS)

    Horas, Jorge A; Olguin, Osvaldo R; Rizzotto, Marcos G

    2005-01-01

    We model the heterogeneous response to radiation of multicellular tumour spheroids assuming position- and volume-dependent radiosensitivity. We propose a method to calculate the overall radiosensitivity parameters to obtain the surviving fraction of tumours. A mathematical model of a spherical tumour with a hypoxic core and a viable rim which is a caricature of a real tumour is constructed. The model is embedded in a two-compartment linear-quadratic (LQ) model, assuming a mixed bivariated Gaussian distribution to attain the radiosensitivity parameters. Ergodicity, i.e., the equivalence between ensemble and volumetric averages is used to obtain the overall radiosensitivities for the two compartments. We obtain expressions for the overall radiosensitivity parameters resulting from the use of both a linear and a nonlinear dependence of the local radiosensitivity with position. The model's results are compared with experimental data of surviving fraction (SF) for multicellular spheroids of different sizes. We make one fit using only the smallest spheroid data and we are able to predict the SF for the larger spheroids. These predictions are acceptable particularly using bounded sensitivities. We conclude with the importance of taking into account the contribution of clonogenic hypoxic cells to radiosensitivity and with the convenience of using bounded local sensitivities to predict overall radiosensitivity parameters

  17. Effects of luteinizing hormone and human chorionic gonadotropin on corpus luteum cells in a spheroid cell culture system.

    Science.gov (United States)

    Walz, A; Keck, C; Weber, H; Kissel, C; Pietrowski, D

    2005-09-01

    The human corpus luteum (CL) is a highly vascularized, temporarily active endocrine gland and consists mainly of granulosa cells (GCs), theca cells (TCs), and endothelial cells (ECs). Its cyclic growth and development takes place under the influence of gonadotropic hormones. If pregnancy does occur, human chorionic gonadotropin (hCG) takes over the function of luteinizing hormone (LH) and, in contrast to LH, extends the functional life span of the CL. In this study, we investigated the effects of hCG and LH in a spheroidal cell culture model of CL development. Our data indicate that GCs secrete factors under the control of hCG that increase sprout formation of EC-spheroids. We demonstrate that the most prominent of these factors is VEGF-A. Furthermore, we found that both LH and hCG decrease sprout formation of GC-spheroids. After forming EC-GC coculture spheroids and consequently bringing GCs and ECs in close contact, sprouting increased under the influence of hCG, however not under LH. These experiments provide evidence for an hCG dependent functional switch in the GCs after coming in contact with ECs. Moreover, it demonstrates the considerably different effects of hCG and LH on GCs although their signaling is transmitted via the same receptor.

  18. Pathways Regulating Spheroid Formation of Human Follicular Thyroid Cancer Cells under Simulated Microgravity Conditions: A Genetic Approach

    Directory of Open Access Journals (Sweden)

    Stefan Riwaldt

    2016-04-01

    Full Text Available Microgravity induces three-dimensional (3D growth in numerous cell types. Despite substantial efforts to clarify the underlying mechanisms for spheroid formation, the precise molecular pathways are still not known. The principal aim of this paper is to compare static 1g-control cells with spheroid forming (MCS and spheroid non-forming (AD thyroid cancer cells cultured in the same flask under simulated microgravity conditions. We investigated the morphology and gene expression patterns in human follicular thyroid cancer cells (UCLA RO82-W-1 cell line after a 24 h-exposure on the Random Positioning Machine (RPM and focused on 3D growth signaling processes. After 24 h, spheroid formation was observed in RPM-cultures together with alterations in the F-actin cytoskeleton. qPCR indicated more changes in gene expression in MCS than in AD cells. Of the 24 genes analyzed VEGFA, VEGFD, MSN, and MMP3 were upregulated in MCS compared to 1g-controls, whereas ACTB, ACTA2, KRT8, TUBB, EZR, RDX, PRKCA, CAV1, MMP9, PAI1, CTGF, MCP1 were downregulated. A pathway analysis revealed that the upregulated genes code for proteins, which promote 3D growth (angiogenesis and prevent excessive accumulation of extracellular proteins, while genes coding for structural proteins are downregulated. Pathways regulating the strength/rigidity of cytoskeletal proteins, the amount of extracellular proteins, and 3D growth may be involved in MCS formation.

  19. Thermal plasma spheroidization and spray deposition of barium titanate powder and characterization of the plasma sprayable powder

    Energy Technology Data Exchange (ETDEWEB)

    Pakseresht, A.H., E-mail: amirh_pak@yahoo.com [Department of Ceramics, Materials and Energy Research Center, P.O. Box 31787-316, Karaj (Iran, Islamic Republic of); Rahimipour, M.R. [Department of Ceramics, Materials and Energy Research Center, P.O. Box 31787-316, Karaj (Iran, Islamic Republic of); Vaezi, M.R. [Department of Nanotechnology and Advanced Materials, Materials and Energy Research Center, P.O. Box 31787-316, Karaj (Iran, Islamic Republic of); Salehi, M. [Department of Materials Engineering, Isfahan University of Technology, P.O. Box 84156-83111, Isfahan (Iran, Islamic Republic of)

    2016-04-15

    In this paper, atmospheric plasma spray method was used to produce dense plasma sprayable powder and thick barium titanate film. In this regard, the commercially feedstock powders were granulated and spheroidized by the organic binder and the thermal spray process, respectively. Scanning electron microscopy was used to investigate the microstructure of the produced powders and the final deposits. X-ray diffraction was also implemented to characterize phase of the sprayed powder. The results indicated that spheroidized powder had suitable flowability as well as high density. The micro-hardness of the film produced by the sprayed powders was higher than that of the film deposited by the irregular granules. Additionally, relative permittivity of the films was increased by decreasing the defects from 160 to 293 for film deposited using spheroidized powder. The reduction in the relative permittivity of deposits, in comparison with the bulk material, was due to the existence of common defects in the thermal spray process. - Highlights: • We prepare sprayable BaTiO{sub 3} powder with no or less inside voids for plasma spray application for first time. • The sprayable powder has good flow characteristics and high density. • Powder spheroidization via plasma spray improves the hardness and dielectric properties of the deposited film.

  20. Thermal plasma spheroidization and spray deposition of barium titanate powder and characterization of the plasma sprayable powder

    International Nuclear Information System (INIS)

    Pakseresht, A.H.; Rahimipour, M.R.; Vaezi, M.R.; Salehi, M.

    2016-01-01

    In this paper, atmospheric plasma spray method was used to produce dense plasma sprayable powder and thick barium titanate film. In this regard, the commercially feedstock powders were granulated and spheroidized by the organic binder and the thermal spray process, respectively. Scanning electron microscopy was used to investigate the microstructure of the produced powders and the final deposits. X-ray diffraction was also implemented to characterize phase of the sprayed powder. The results indicated that spheroidized powder had suitable flowability as well as high density. The micro-hardness of the film produced by the sprayed powders was higher than that of the film deposited by the irregular granules. Additionally, relative permittivity of the films was increased by decreasing the defects from 160 to 293 for film deposited using spheroidized powder. The reduction in the relative permittivity of deposits, in comparison with the bulk material, was due to the existence of common defects in the thermal spray process. - Highlights: • We prepare sprayable BaTiO_3 powder with no or less inside voids for plasma spray application for first time. • The sprayable powder has good flow characteristics and high density. • Powder spheroidization via plasma spray improves the hardness and dielectric properties of the deposited film.

  1. THE ACS LCID PROJECT. I. SHORT-PERIOD VARIABLES IN THE ISOLATED DWARF SPHEROIDAL GALAXIES CETUS AND TUCANA

    NARCIS (Netherlands)

    Bernard, Edouard J.; Monelli, Matteo; Gallart, Carme; Drozdovsky, Igor; Stetson, Peter B.; Aparicio, Antonio; Cassisi, Santi; Mayer, Lucio; Cole, Andrew A.; Hidalgo, Sebastian L.; Skillman, Evan D.; Tolstoy, Eline

    2009-01-01

    We present the first study of the variable star populations in the isolated dwarf spheroidal galaxies (dSphs) Cetus and Tucana. Based on Hubble Space Telescope images obtained with the Advanced Camera for Surveys in the F475W and F814W bands, we identified 180 and 371 variables in Cetus and Tucana,

  2. Hypofractionated radiation induces a decrease in cell proliferation but no histological damage to organotypic multicellular spheroids of human glioblastomas

    NARCIS (Netherlands)

    Kaaijk, P.; Troost, D.; Sminia, P.; Hulshof, M. C.; van der Kracht, A. H.; Leenstra, S.; Bosch, D. A.

    1997-01-01

    The aim of this study was to examine the effect of radiation on glioblastoma, using an organotypic multicellular spheroid (OMS) model. Most glioblastoma cell lines are, in contrast to glioblastomas in vivo, relatively radiosensitive. This limits the value of using cell lines for studying the

  3. Cytolytic effects of autologous lymphokine-activated killer cells on organotypic multicellular spheroids of gliomas in vitro

    NARCIS (Netherlands)

    Kaaijk, P.; Troost, D.; Dast, P. K.; van den Berg, F.; Leenstra, S.; Bosch, D. A.

    1995-01-01

    Knowledge about lymphokine-activated killer (LAK) cell infiltration and LAK cell cytotoxicity is essential to improve the effectiveness of LAK cell therapy against gliomas. In the present study, organotypic multicellular spheroids (OMS) of glioma tissue were used as a culture model to study the

  4. Studies of dust shells around stars

    International Nuclear Information System (INIS)

    Bedijn, P.J.

    1977-01-01

    This thesis deals with some aspects of circumstellar dust shells. This dust shell, emitting infrared radiation, is described by way of its absorptive and emissive properties as well as by the transfer of radiation through the dust shell itself. Model calculations are compared to experimental results and agree reasonably well. The author also discusses the dynamics of the extended shells of gas and dust around newly formed stars

  5. Quadrupole moment of the 7/21- isomer state in 43S. Shell model study of sulfur isotopes around N=28

    International Nuclear Information System (INIS)

    Chevrier, Raphael

    2013-01-01

    The goal of this work consists in providing new insights in the shape coexistence expected in neutron-rich nuclei around the N=28 shell closure. In 43 S, recent experimental data as well as their interpretation in the shell model framework were used to predict the coexistence between a J π =3/2 1 - prolate deformed ground state and a 7/2 1 - rather spherical isomer state. We report on the quadrupole moment measurement Q s of the 7/2 1 - isomer state [E*=320.5(5) keV, T 1/2 =415(3) ns] in 43 S. The TDPAD method was applied on 43 S nuclei produced by the fragmentation of a 48 Ca primary beam at 345 A.MeV, and selected in-flight through the BigRIPS spectrometer at RIKEN (Japan). The measured value, |Q s |=23(3) efm 2 , is in remarkable agreement with that calculated in the shell model framework, although it is significantly larger than that expected for a single-particle state. In order to understand the nature of the correlations responsible for the departure of the isomer state from a pure spherical shape, we report on the results of a shell model study using the modern SDPF-U interaction of the neighbors sulfur isotopes 42,44,46 S. Those calculations allowed to identify a slight triaxial degree of freedom in the structure of these nuclei, although the latter happens to be highly hindered at N=28 in 44 S. Spectroscopic factor calculations show that this slight triaxial degree of freedom also impacts the low-lying structure in 43 S. It allows to better understand the deviation of the spectroscopic quadrupole moment value of the isomer state from the limit case of a pure spherical state. (author) [fr

  6. Comparative proteome analysis of monolayer and spheroid culture of canine osteosarcoma cells.

    Science.gov (United States)

    Gebhard, Christiane; Miller, Ingrid; Hummel, Karin; Neschi Née Ondrovics, Martina; Schlosser, Sarah; Walter, Ingrid

    2018-04-15

    Osteosarcoma is an aggressive bone tumor with high metastasis rate in the lungs and affects both humans and dogs in a similar way. Three-dimensional tumor cell cultures mimic the in vivo situation of micro-tumors and metastases and are therefore better experimental in vitro models than the often applied two-dimensional monolayer cultures. The aim of the present study was to perform comparative proteomics of standard monolayer cultures of canine osteosarcoma cells (D17) and three-dimensional spheroid cultures, to better characterize the 3D model before starting with experiments like migration assays. Using DIGE in combination with MALDI-TOF/TOF we found 27 unique canine proteins differently represented between these two culture systems, most of them being part of a functional network including mainly chaperones, structural proteins, stress-related proteins, proteins of the glycolysis/gluconeogenesis pathway and oxidoreductases. In monolayer cells, a noticeable shift to more acidic pI values was noticed for several proteins of medium to high abundance; two proteins (protein disulfide isomerase A3, stress-induced-phosphoprotein 1) showed an increase of phosphorylated protein species. Protein distribution within the cells, as detected by immunohistochemistry, displayed a switch of stress-induced-phosphoprotein 1 from the cytoplasm (in monolayer cultures) to the nucleus (in spheroid cultures). Additionally, Western blot testing revealed upregulated concentrations of metastasin (S100A4), triosephosphate isomerase 1 and septin 2 in spheroid cultures, in contrast to decreased concentrations of CCT2, a subunit of the T-complex. Results indicate regulation of stress proteins in the process of three-dimensional organization characterized by a hypoxic and nutrient-deficient environment comparable to tumor micro-metastases. Osteosarcoma is an aggressive bone tumor that early spreads to the lungs. Three-dimensional tumor cell cultures represent the avascular stage of micro

  7. 7 CFR 983.29 - Shelled pistachios.

    Science.gov (United States)

    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 pistachio...

  8. Thin-shell wormholes in dilaton gravity

    International Nuclear Information System (INIS)

    Eiroa, Ernesto F.; Simeone, Claudio

    2005-01-01

    In this work we construct charged thin-shell Lorentzian wormholes in dilaton gravity. The exotic matter required for the construction is localized in the shell and the energy conditions are satisfied outside the shell. The total amount of exotic matter is calculated and its dependence with the parameters of the model is analyzed

  9. Shell film- and video catalogue 1996

    International Nuclear Information System (INIS)

    1996-01-01

    An overview is given of films and videos that are available through 'Shell Nederland Filmcentrale' (Shell Netherlands Film Center), subdivided into the subjects (1) About Shell; (2) Health, Safety and Environment; (3) Science and Technology; (4) The History of Car(racing); and (5) Historical Overview. 5 ills

  10. A finite element for plates and shells

    International Nuclear Information System (INIS)

    Muller, A.; Feijoo, R.A.; Bevilacqua, L.

    1981-08-01

    A simple triangular finite element for plates and shells, is presented. Since the rotation fields are assumed independent of the displacement fields, the element allows one to solve thick shells problems. In the limit for thin shell, the Kirchoff-Love hypothesis is automatically satisfied, thus enlarging its range of application. (Author) [pt

  11. Vibrations of Thin Piezoelectric Shallow Shells

    Indian Academy of Sciences (India)

    Abstract. In this paper we consider the eigenvalue problem for piezoelectric shallow shells and we show that, as the thickness of the shell goes to zero, the eigensolutions of the three-dimensional piezoelectric shells converge to the eigensolutions of a two-dimensional eigenvalue problem.

  12. 7 CFR 981.6 - Shelled almonds.

    Science.gov (United States)

    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 after...

  13. Extensions to a nonlinear finite-element axisymmetric shell model based on Reissner's shell theory

    International Nuclear Information System (INIS)

    Cook, W.A.

    1981-01-01

    Extensions to shell analysis not usually associated with shell theory are described in this paper. These extensions involve thick shells, nonlinear materials, a linear normal stress approximation, and a changing shell thickness. A finite element shell-of-revolution model has been developed to analyze nuclear material shipping containers under severe impact conditions. To establish the limits for this shell model, the basic assumptions used in its development were studied; these are listed in this paper. Several extensions were evident from the study of these limits: a thick shell, a plastic hinge, and a linear normal stress

  14. Time- and cell-resolved dynamics of redox-sensitive Nrf2, HIF and NF-κB activities in 3D spheroids enriched for cancer stem cells

    Directory of Open Access Journals (Sweden)

    Anna P. Kipp

    2017-08-01

    Full Text Available Cancer cells have an altered redox status, with changes in intracellular signaling pathways. The knowledge of how such processes are regulated in 3D spheroids, being well-established tumor models, is limited. To approach this question we stably transfected HCT116 cells with a pTRAF reporter that enabled time- and cell-resolved activity monitoring of three redox-regulated transcription factors Nrf2, HIF and NF-κB in spheroids enriched for cancer stem cells. At the first day of spheroid formation, these transcription factors were activated and thereafter became repressed. After about a week, both HIF and Nrf2 were reactivated within the spheroid cores. Further amplifying HIF activation in spheroids by treatment with DMOG resulted in a dominant quiescent stem-cell-like phenotype, with high resistance to stress-inducing treatments. Auranofin, triggering oxidative stress and Nrf2 activation, had opposite effects with increased differentiation and proliferation. These novel high-resolution insights into spatiotemporal activation patterns demonstrate a striking coordination of redox regulated transcription factors within spheroids not occurring in conventional cell culture models. Keywords: Redox regulation, Cancer stem cells, Spheroids, Nrf2, HIF, NF-κB

  15. Evaluation of anti-HER2 scFv-conjugated PLGA–PEG nanoparticles on 3D tumor spheroids of BT474 and HCT116 cancer cells

    International Nuclear Information System (INIS)

    Le, Thi Thuy Duong; Pham, Thu Hong; Ngo, Thi Hong Giang; Le, Quang Huan; Nguyen, Trong Nghia; Hoang, Thi My Nhung

    2016-01-01

    Three-dimensional culture cells (spheroids) are one of the multicellular culture models that can be applied to anticancer chemotherapeutic development. Multicellular spheroids more closely mimic in vivo tumor-like patterns of physiologic environment and morphology. In previous research, we designed docetaxel-loaded pegylated poly(D, L-lactide-co-glycolide) nanoparticles conjugated with anti-HER2 single chain antibodies (scFv–Doc–PLGA–PEG) and evaluated them in 2D cell culture. In this study, we continuously evaluate the cellular uptake and cytotoxic effect of scFv–Doc–PLGA–PEG on a 3D tumor spheroid model of BT474 (HER2-overexpressing) and HCT116 (HER2-underexpressing) cancer cells. The results showed that the nanoparticle formulation conjugated with scFv had a significant internalization effect on the spheroids of HER2-overexpressing cancer cells as compared to the spheroids of HER2-underexpressing cancer cells. Therefore, cytotoxic effects of targeted nanoparticles decreased the size and increased necrotic score of HER2-overexpressing tumor spheroids. Thus, these scFv–Doc–PLGA–PEG nanoparticles have potential for active targeting for HER2-overexpressing cancer therapy. In addition, BT474 and HCT116 spheroids can be used as a tumor model for evaluation of targeting therapies. (paper)

  16. A Model for Spheroid versus Monolayer Response of SK-N-SH Neuroblastoma Cells to Treatment with 15-Deoxy-PGJ2

    Directory of Open Access Journals (Sweden)

    Dorothy I. Wallace

    2016-01-01

    Full Text Available Researchers have observed that response of tumor cells to treatment varies depending on whether the cells are grown in monolayer, as in vitro spheroids or in vivo. This study uses data from the literature on monolayer treatment of SK-N-SH neuroblastoma cells with 15-deoxy-PGJ2 and couples it with data on growth rates for untreated SK-N-SH neuroblastoma cells grown as multicellular spheroids. A linear model is constructed for untreated and treated monolayer data sets, which is tuned to growth, death, and cell cycle data for the monolayer case for both control and treatment with 15-deoxy-PGJ2. The monolayer model is extended to a five-dimensional nonlinear model of in vitro tumor spheroid growth and treatment that includes compartments of the cell cycle (G1,S,G2/M as well as quiescent (Q and necrotic (N cells. Monolayer treatment data for 15-deoxy-PGJ2 is used to derive a prediction of spheroid response under similar treatments. For short periods of treatment, spheroid response is less pronounced than monolayer response. The simulations suggest that the difference in response to treatment of monolayer versus spheroid cultures observed in laboratory studies is a natural consequence of tumor spheroid physiology rather than any special resistance to treatment.

  17. Visualizing the effect of tumor microenvironments on radiation-induced cell kinetics in multicellular spheroids consisting of HeLa cells

    International Nuclear Information System (INIS)

    Kaida, Atsushi; Miura, Masahiko

    2013-01-01

    Highlights: •We visualized radiation-induced cell kinetics in spheroids. •HeLa-Fucci cells were used for detection of cell-cycle changes. •Radiation-induced G2 arrest was prolonged in the spheroid. •The inner and outer cell fractions behaved differently. -- Abstract: In this study, we visualized the effect of tumor microenvironments on radiation-induced tumor cell kinetics. For this purpose, we utilized a multicellular spheroid model, with a diameter of ∼500 μm, consisting of HeLa cells expressing the fluorescent ubiquitination-based cell-cycle indicator (Fucci). In live spheroids, a confocal laser scanning microscope allowed us to clearly monitor cell kinetics at depths of up to 60 μm. Surprisingly, a remarkable prolongation of G2 arrest was observed in the outer region of the spheroid relative to monolayer-cultured cells. Scale, an aqueous reagent that renders tissues optically transparent, allowed visualization deeper inside spheroids. About 16 h after irradiation, a red fluorescent cell fraction, presumably a quiescent G0 cell fraction, became distinct from the outer fraction consisting of proliferating cells, most of which exhibited green fluorescence indicative of G2 arrest. Thereafter, the red cell fraction began to emit green fluorescence and remained in prolonged G2 arrest. Thus, for the first time, we visualized the prolongation of radiation-induced G2 arrest in spheroids and the differences in cell kinetics between the outer and inner fractions

  18. Effect of apoptosis and response of extracellular matrix proteins after chemotherapy application on human breast cancer cell spheroids.

    Science.gov (United States)

    Oktem, G; Vatansever, S; Ayla, S; Uysal, A; Aktas, S; Karabulut, B; Bilir, A

    2006-02-01

    Multicellular tumor spheroid (MTS) represents a three-dimensional structural form of tumors in laboratory conditions, and it has the characteristics of avascular micrometastases or intervascular spaces of big tumors. Recent studies indicate that extracellular matrix (ECM) proteins play a critical role in tumor metastasis, therefore normal and cancer cells require an ECM for survival, proliferation and differentiation. Doxorubicin and Docetaxel are widely used in the therapy of breast cancer, as well as in in vivo and in vitro studies. In this study, we examined the effect of apoptosis and proliferation of cells on the human breast cancer cell line, MCF-7, by using p53, bcl-2 and Ki67 gene expression, and the tendency to metastasis with extracellular matrix proteins, laminin and type IV collagen after chemotherapy in the spheroid model. The apoptotic cell death in situ was detected by TUNEL method. TUNEL-positive cells and positive immunoreactivities of laminin, type IV collagen, p53 and, bcl-2 were detected in the control group. There was no laminin and type IV collagen immunoreactivities in spheroids of drug groups. While TUNEL-positive cells and p53 immunoreactivity were detected in Docetaxel, Doxorubicin and Docetaxel/Doxorubicin groups, p53 immunoreactivity was not observed in the Docetaxel group. There was no bcl-2 immunoreactivity in either drug group. In addition, we did not detect Ki67 immunoreactivity in both control and drug treatment groups. However, the absence of Ki67 protein in MCF-7 breast multicellular tumor spheroids is possibly related to the cells in G0 or S phase. These chemotherapeutic agents may affect the presence of ECM proteins in this in vitro model of micrometastasis of spheroids. These findings suggest that the possible mechanism of cell death in Doxorubicin and Docetaxel/Doxorubicin treatment groups is related to apoptosis through the p53 pathway. However, we considered the possibility that there is another control mechanism for the

  19. In vitro analysis of scaffold-free prevascularized microtissue spheroids containing human dental pulp cells and endothelial cells.

    Science.gov (United States)

    Dissanayaka, Waruna Lakmal; Zhu, Lifang; Hargreaves, Kenneth M; Jin, Lijian; Zhang, Chengfei

    2015-05-01

    Scaffolds often fail to mimic essential functions of the physiologic extracellular matrix (ECM) that regulates cell-cell communication in tissue microenvironments. The development of scaffold-free microtissues containing stem cell-derived ECM may serve as a successful alternative to the use of artificial scaffolds. The current study aimed to fabricate 3-dimensional microtissue spheroids of dental pulp cells (DPCs) prevascularized by human umbilical vein endothelial cells (HUVECs) and to characterize these scaffold-free spheroids for the in vitro formation of pulplike tissue constructs. Three-dimensional microtissue spheroids of DPC alone and DPC-HUVEC co-cultures were fabricated using agarose micro-molds. Cellular organization within the spheroids and cell viability (live/dead assay) were assessed at days 1, 7, and 14. Microtissue spheroids were allowed to self-assemble into macrotissues, induced for odontogenic differentiation (21 days), and examined for expression levels of osteo/odontogenic markers: alkaline phosphatase, bone sialoprotein and RUNX2 (Real-time PCR), mineralization (von-Kossa), and prevascularisation (immunohistochemistry for CD31). The DPC microtissue microenvironment supported HUVEC survival and capillary network formation in the absence of a scaffolding material and external angiogenic stimulation. Immunohistochemical staining for CD31 showed the capillary network formed by HUVECs did sustain-for a prolonged period-even after the microtissues transformed into a macrotissue. Induced, prevascularized macrotissues showed enhanced differentiation capacity compared with DPC alone macrotissues, as shown by higher osteo/odontogenic gene expression levels and mineralization. These findings provide insight into the complex intercellular cross talk occurring between DPCs and HUVECs in the context of angiogenesis and pulp regeneration and highlight the significance of developing a favorable 3-dimensional microenvironment that can, in turn, contribute

  20. The formation of Dwarf Spheroidal galaxies by the dissolving star cluster model.

    Science.gov (United States)

    Alarcon, Alex; Theory and Star Formation Group

    2018-01-01

    Dwarf spheroidal (dSph) galaxies are regarded as key object in the formation of larger galaxies and are believed to be the most dark matter dominated systems known. There are several model that attempt to explain their formation, but they have problems to model the formation of isolated dSph. Here we will explain a possible formation scenario in which star clusters form in the dark matter halo of a dSph. these cluster suffer from low star formation efficiency and dissolve while orbiting inside the halo. Thereby they build the faint luminous components that we observe in dSph galaxies. Here we will show the main results of this simulations and how they would be corroborated using observational data.