326 research outputs found
Adhesion model of side contact for an extensible elastic fiber
AbstractFor accurately predicted adhesion laws of fibrillar structures contribute to the rational design of high-performance biomimetic adhesives, an adhesion model is proposed to study the directional adhesion behavior of an extensible elastic fiber that contacts a rigid smooth surface with its side surface under the coupling effect of normal and shear forces, based on the extensible Euler Bernoulli beam theory and the surface energy concept. The deformed configuration of the fiber is obtained analytically, and on the basis of this result, the detachment mode and the normal pull-off force of the fiber for a given shear force are predicted directly. It is also found that, due to the extensibility of the fiber, there exists a maximum normal pull-off force (MNPF) when an optimal shear force is applied. The MNPF will be enhanced by increasing the axial stiffness, and reduced by increasing the bending stiffness. In addition, generating an optimal pre-tension in the adhered part of the fiber will maximize the MNPF. The derived adhesion law is expected to contribute to the optimal design and applications of single-level fibrillar adhesives
Optimal Energy Dissipation in Sliding Friction Simulations
Non-equilibrium molecular dynamics simulations, of crucial importance in
sliding friction, are hampered by arbitrariness and uncertainties in the
removal of the frictionally generated Joule heat. Building upon general
pre-existing formulation, we implement a fully microscopic dissipation approach
which, based on a parameter-free, non-Markovian, stochastic dynamics, absorbs
Joule heat equivalently to a semi-infinite solid and harmonic substrate. As a
test case, we investigate the stick-slip friction of a slider over a
two-dimensional Lennard-Jones solid, comparing our virtually exact frictional
results with approximate ones from commonly adopted dissipation schemes.
Remarkably, the exact results can be closely reproduced by a standard Langevin
dissipation scheme, once its parameters are determined according to a general
and self-standing variational procedure
Bulk properties of light deformed nuclei derived from a medium-modified meson-exchange interaction
Deformed Hartree-Fock-Bogoliubov calculations for finite nuclei are carried
out. As residual interaction, a Brueckner G-matrix derived from a
meson-exchange potential is taken. Phenomenological medium modifications of the
meson masses are introduced. The binding energies, radii, and deformation
parameters of the Carbon, Oxygen, Neon, and Magnesium isotope chains are found
to be in good agreement with the experimental data.Comment: 10 pages, LaTeX2e, elsart, 4 eps-figures includes with graphic
Revisión sobre métodos de preparación, mecanismos y aplicaciones de péptidos antioxidantes en aceites
Natural antioxidants, especially those used in edible oil, are safer compared to chemically synthesized antioxidants. Therefore, research on natural antioxidants has become prevelant. Antioxidant peptides derived from food protein can effectively prevent oil oxidation. Protein hydrolyzation is widely applied for the production of antioxidant peptides in industry, and bioinformatics is employed nowadays to generate the desired peptide sequence. Furthermore, the mechanism of antioxidant peptides in the oil system is still controversial, which limits the further development of antioxidant peptides as food antioxidants. This review introduces the preparation method of antioxidant peptides and their mechanisms as well as applications in the oil. It will help to comprehensively understand the function of antioxidant peptides and promote their development in the oil field.Los antioxidantes naturales, especialmente utilizados en aceites comestibles, son más seguros en comparación con los antioxidantes sintetizados quÃmicamente. Por lo tanto, la investigación sobre antioxidantes naturales se convierte en un punto de interés. Los péptidos antioxidantes derivados de las proteÃnas alimentarias pueden prevenir eficazmente la oxidación del aceite. La hidrolización de proteÃnas se usa ampliamente en la industria para la producción de péptidos antioxidantes y la bioinformática se emplea hoy en dÃa para generar la secuencia de péptidos deseada. Además, el mecanismo de los péptidos antioxidantes en el sistema oleoso sigue siendo controvertido, lo que limita el desarrollo posterior de péptidos antioxidantes como antioxidantes alimentarios. Esta revisión presenta el método de preparación de péptidos antioxidantes y su mecanismo, asà como las aplicaciones en aceite, lo que ayudará a comprender de manera integral la función de los péptidos antioxidantes y promoverá su desarrollo en el campo petrolero
Correlated noise in a logistic growth model
The logistic differential equation is used to analyze cancer cell population,
in the presence of a correlated Gaussian white noise. We study the steady state
properties of tumor cell growth and discuss the effects of the correlated
noise. It is found that the degree of correlation of the noise can cause tumor
cell extinction.Comment: 3 pages, 4 figure
Analysis of the vector meson transitions among the heavy quarkonium states
In this article, we study the vector meson transitions among the charmonium
and bottomonium states with the heavy quark effective theory in an systematic
way, and make predictions for the ratios among the vector meson decay widths of
a special multiplet to another multiplet. The predictions can be confronted
with the experimental data in the future.Comment: 14 pages, published versio
Charmonium states in QCD-inspired quark potential model using Gaussian expansion method
We investigate the mass spectrum and electromagnetic processes of charmonium
system with the nonperturbative treatment for the spin-dependent potentials,
comparing the pure scalar and scalar-vector mixing linear confining potentials.
It is revealed that the scalar-vector mixing confinement would be important for
reproducing the mass spectrum and decay widths, and therein the vector
component is predicted to be around 22%. With the state wave functions obtained
via the full-potential Hamiltonian, the long-standing discrepancy in M1
radiative transitions of and are alleviated
spontaneously. This work also intends to provide an inspection and suggestion
for the possible among the copious higher charmonium-like states.
Particularly, the newly observed X(4160) and X(4350) are found in the
charmonium family mass spectrum as MeV and MeV, which strongly favor the assignments
respectively. The corresponding radiative transitions, leptonic and two-photon
decay widths have been also predicted theoretically for the further
experimental search.Comment: 16 pages,3 figure
Effect of collision cascades on dislocations in tungsten: A molecular dynamics study
Tungsten (W) is the prime candidate material for the divertor and other plasma-facing components in DEMO. The point defects (i.e. vacancies and self-interstitials) produced in collision cascades caused by incident neutrons aggregate into dislocation loops (and voids), which strongly affect the mechanical properties. The point defects also interact with existing microstructural features, and understanding these processes is crucial for modelling the long term microstructural evolution of the material under fusion conditions. In this work, we performed molecular dynamics simulations of cascades interacting with initially straight edge dislocation dipoles. It was found that the residual vacancy number usually exceeds the residual interstitial number for cascades interacting with vacancy type dipoles, but for interstitial type dipoles these are close. We observed that a cascade near a dislocation promotes climb, i.e. it facilitates the movement of point defects along the climb direction. We also observed that the dislocations move easily along the glide direction, and that kinks are formed near the centre of the cascade, which then facilitate the movement of the dipoles. Some dipoles are sheared off by the cascade, and this is dependent on PKA energy, position, direction, and the width of dipole
Case study of simultaneous observations of sporadic sodium layer, E-region field-aligned irregularities and sporadic E layer at low latitude of China
Direct Measurements of the Branching Fractions for and and Determinations of the Form Factors and
The absolute branching fractions for the decays and
are determined using singly
tagged sample from the data collected around 3.773 GeV with the
BES-II detector at the BEPC. In the system recoiling against the singly tagged
meson, events for and events for decays are observed. Those yield
the absolute branching fractions to be and . The
vector form factors are determined to be
and . The ratio of the two form
factors is measured to be .Comment: 6 pages, 5 figure
- …