10,720 research outputs found
Possible Way to Synthesize Superheavy Element Z=117
Within the framework of the dinuclear system model, the production of
superheavy element Z=117 in possible projectile-target combinations is analyzed
systematically. The calculated results show that the production cross sections
are strongly dependent on the reaction systems. Optimal combinations,
corresponding excitation energies and evaporation channels are proposed in this
letter, such as the isotopes ^{248,249}Bk in ^{48}Ca induced reactions in 3n
evaporation channels and the reactions ^{45}Sc+^{246,248}Cm in 3n and 4n
channels, and the system ^{51}V+^{244}Pu in 3n channel.Comment: 10 pages, 4 figures, 1 tabl
Probing the equation of state of neutron-rich matter with intermediate energy heavy-ion collisions
Nuclear reactions induced by stable and/or radioactive neutron-rich nuclei
provide the opportunity to pin down the equation of state of neutron-rich
matter, especially the density () dependence of its isospin-dependent
part, i.e., the nuclear symmetry energy . A conservative
constraint, , around the nuclear matter saturation density has
recently been obtained from the isospin diffusion data in intermediate energy
heavy-ion collisions. We review this exciting result and discuss its
consequences and implications on nuclear effective interactions, radii and
cooling mechanisms of neutron stars.Comment: 10 pages. Invited talks at (1) International Workshop on Nuclear
Multifragmentation, Nov. 28-Dec. 1, 2005, Catania, Italy and (2) XXIX
Symposium on Nuclear Physics, Jan. 3-6, 2006, Cocoyoc, Morelos, Mexic
Constraining the Skyrme effective interactions and the neutron skin thickness of nuclei using isospin diffusion data from heavy ion collisions
Recent analysis of the isospin diffusion data from heavy-ion collisions based
on an isospin- and momentum-dependent transport model with in-medium
nucleon-nucleon cross sections has led to the extraction of a value of MeV for the slope of the nuclear symmetry energy at saturation density.
This imposes stringent constraints on both the parameters in the Skyrme
effective interactions and the neutron skin thickness of heavy nuclei. Among
the 21 sets of Skyrme interactions commonly used in nuclear structure studies,
the 4 sets SIV, SV, G, and R are found to give values
that are consistent with the extracted one. Further study on the correlations
between the thickness of the neutron skin in finite nuclei and the nuclear
matter symmetry energy in the Skyrme Hartree-Fock approach leads to predicted
thickness of the neutron skin of fm for Pb, fm for Sn, and fm for Sn.Comment: 10 pages, 4 figures, 1 Table, Talk given at 1) International
Conference on Nuclear Structure Physics, Shanghai, 12-17 June, 2006; 2) 11th
China National Nuclear Structure Physics Conference, Changchun, Jilin, 13-18
July, 200
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Nanoparticles for live cell microscopy: A surface-enhanced Raman scattering perspective.
Surface enhanced Raman scattering (SERS) nanoparticles are an attractive alternative to fluorescent probes for biological labeling because of their photostability and multiplexing capabilities. However, nanoparticle size, shape, and surface properties are known to affect nanoparticle-cell interactions. Other issues such as the formation of a protein corona and antibody multivalency interfere with the labeling properties of nanoparticle-antibody conjugates. Hence, it is important to consider these aspects in order to validate such conjugates for live cell imaging applications. Using SERS nanoparticles that target HER2 and CD44 in breast cancer cells, we demonstrate labeling of fixed cells with high specificity that correlates well with fluorescent labels. However, when labeling live cells to monitor surface biomarker expression and dynamics, the nanoparticles are rapidly uptaken by the cells and become compartmentalized into different cellular regions. This behavior is in stark contrast to that of fluorescent antibody conjugates. This study highlights the impact of nanoparticle internalization and trafficking on the ability to use SERS nanoparticle-antibody conjugates to monitor cell dynamics
Study of axial strain induced torsion of single wall carbon nanotubes by 2D continuum anharmonic anisotropic elastic model
Recent molecular dynamic simulations have found chiral single wall carbon
nanotubes (SWNTs) twist during stretching, which is similar to the motion of a
screw. Obviously this phenomenon, as a type of curvature-chirality effect, can
not be explained by usual isotropic elastic theory of SWNT. More interestingly,
with larger axial strains (before buckling), the axial strain induced torsion
(a-SIT) shows asymmetric behaviors for axial tensile and compressing strains,
which suggests anharmonic elasticity of SWNTs plays an important role in real
a-SIT responses. In order to study the a-SIT of chiral SWNTs with actual sizes,
and avoid possible deviations of computer simulation results due to the
finite-size effect, we propose a 2D analytical continuum model which can be
used to describe the the SWNTs of arbitrary chiralities, curvatures, and
lengths, with the concerning of anisotropic and anharmonic elasticity of SWNTs.
This elastic energy of present model comes from the continuum limit of lattice
energy based on Second Generation Reactive Empirical Bond Order potential
(REBO-II), a well-established empirical potential for solid carbons. Our model
has no adjustable parameters, except for those presented in REBO-II, and all
the coefficients in the model can be calculated analytically. Using our method,
we obtain a-SIT responses of chiral SWNTs with arbitrary radius, chiralities
and lengthes. Our results are in reasonable agreement with recent molecular
dynamic simulations. [Liang {\it et. al}, Phys. Rev. Lett, , 165501
(2006).] Our approach can also be used to calculate other curvature-chirality
dependent anharmonic mechanic responses of SWNTs.Comment: 14 pages, 2 figure
Quantum-defect theory of resonant charge exchange
We apply the quantum-defect theory for potential to study the
resonant charge exchange process. We show that by taking advantage of the
partial-wave-insensitive nature of the formulation, resonant charge exchange of
the type of S+S can be accurately described over a wide range of
energies using only three parameters, such as the \textit{gerade} and the
\textit{ungerade} wave scattering lengths, and the atomic polarizability,
even at energies where many partial waves contribute to the cross sections. The
parameters can be determined experimentally, without having to rely on accurate
potential energy surfaces, of which few exist for ion-atom systems. The theory
further relates ultracold interactions to interactions at much higher
temperatures.Comment: 8 pages, 7 figure
Nuclear matter symmetry energy and the neutron skin thickness of heavy nuclei
Correlations between the thickness of the neutron skin in finite nuclei and
the nuclear matter symmetry energy are studied in the Skyrme Hartree-Fock
model. From the most recent analysis of the isospin diffusion data in heavy-ion
collisions based on an isospin- and momentum-dependent transport model with
in-medium nucleon-nucleon cross sections, a value of MeV for the
slope of the nuclear symmetry energy at saturation density is extracted, and
this imposes stringent constraints on both the parameters in the Skyrme
effective interactions and the neutron skin thickness of heavy nuclei.
Predicted thickness of the neutron skin is fm for Pb,
fm for Sn, and fm for Sn.Comment: 6 pages, 4 figures, 1 table, revised version, to appear in PR
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