203 research outputs found
Sigma-phase in Fe-Cr and Fe-V alloy systems and its physical properties
A review is presented on physical properties of the sigma-phase in Fe-Cr and
Fe-V alloy systems as revealed both with experimental -- mostly with the
Mossbauer spectroscopy -- and theoretical methods. In particular, the following
questions relevant to the issue have been addressed: identification of sigma
and determination of its structural properties, kinetics of alpha-to-sigma and
sigma-to-alpha phase transformations, Debye temperature and Fe-partial phonon
density of states, Curie temperature and magnetization, hyperfine fields,
isomer shifts and electric field gradients.Comment: 26 pages, 23 figures and 83 reference
Finite-time blowup in a supercritical quasilinear parabolic-parabolic Keller-Segel system in dimension 2
In this paper we prove finite-time blowup of radially symmetric solutions to
the quasilinear parabolic-parabolic two-dimensional Keller-Segel system for any
positive mass. This is done in case of nonlinear diffusion and also in the case
of nonlinear cross-diffusion provided the nonlinear chemosensitivity term is
assumed not to decay. Moreover, it is shown that the above-mentioned lack of
non-decay assumption is essential with respect to keeping the dichotomy
finite-time blowup against boundedness of solutions. Namely, we prove that
without the non-decay assumption possible asymptotic behaviour of solutions
includes also infinite-time blowup.Comment: 14 page
Long-time behavior of an angiogenesis model with flux at the tumor boundary
This paper deals with a nonlinear system of partial differential equations
modeling a simplified tumor-induced angiogenesis taking into account only the
interplay between tumor angiogenic factors and endothelial cells. Considered
model assumes a nonlinear flux at the tumor boundary and a nonlinear
chemotactic response. It is proved that the choice of some key parameters
influences the long-time behaviour of the system. More precisely, we show the
convergence of solutions to different semi-trivial stationary states for
different range of parameters.Comment: 17 page
Phylogeographic patterns of steppe species in Eastern Central Europe: a review and the implications for conservation
L
Stealth nanocarriers based sterosomes using PEG post-insertion process
Sterosomes (STEs), a new and promising non-phospholipidic liposome platform based on palmitic acid (PA) and cholesterol (Chol) mixtures, need to have polyethylene glycol (PEG) chains grafted to their surface in order to obtain long-circulating nanocarriers in the blood stream. A post-insertion method was chosen to achieve this modification. The post-insertion process of PEG-modified distearoylphosphoethanolamine (DSPE-PEG) was monitored using the zeta potential value of STEs. Various conditions including PEG chain length and the DSPE-PEG/PA-Chol ratio, were explored. Zeta potential of STEs changed from about -40mV for non-modified STEs to values close to 0 mV by the end of the process, i.e. for PEG-modified STEs. The kinetics of DSPE-PEG insertion and the stability of the resulting PEG-modified STEs were not considerably influenced, within the investigated range, by changes in PEG chain lengths and in DSPE-PEG/PA-Chol proportion. The post-insertion of PEG chains reduced in vitro complement activation as well as in vitro macrophage uptake compared to the non-modified STEs. Moreover, longer blood circulation time in mice was established for PEG-modified STEs intravenously injected compared to non-modified STEs. These results establish that post-insertion process of PEG chains to STEs is a promising strategy for developing long-term circulating drug delivery nanocarriers
Removal of nicotine from indoor air using titania-modified polypropylene fibers: nicotine decomposition by titania-modified polypropylene fibers
Well-posedness for a model of individual clustering
25 pagesInternational audienceWe study the well-posedness of a model of individual clustering. Given p > N ≥ 1 and an initial condition in W 1,p (Ω), the local existence and uniqueness of a strong solution is proved. We next consider two specific reproduction rates and show global existence if N = 1, as well as, the convergence to steady states for one of these rates
Evidence for Different Freeze-Out Radii of High- and Low-Energy Pions Emitted in Au+Au Collisions at 1 GeV/nucleon
Double differential production cross sections of negative and positive pions
and the number of participating protons have been measured in central Au+Au
collisions at 1 GeV per nucleon incident energy. At low pion energies the pi^-
yield is strongly enhanced over the pi^+ yield. The energy dependence of the
pi^-/pi^+ ratio is assigned to the Coulomb interaction of the charged pions
with the protons in the reaction zone. The deduced Coulomb potential increases
with increasing pion c.m. energy. This behavior indicates different freeze-out
radii for different pion energies in the c.m.~frame.Comment: IKDA is the Institute for Nuclear Physics in Darmstadt/German
Dynamic Response Characteristics in Variable Stiffness Soft Inflatable Links
© Springer Nature Switzerland AG 2019. In soft robotics, there is the fundamental need to develop devices that are flexible and can change stiffness in order to work safely in the vicinity of humans. Moreover, these structures must be rigid enough to withstand the force application and accuracy in motion. To solve these issues, previous research proposed to add a compliance element between motor and load – Series Elastic Actuators (SEAs). This approach benefits from improved force control and shock tolerance due to the elasticity introduced at joint level. However, series compliance at the joint level comes at the cost of inferior position controllability and additional mechanical complexity. In this research, we move the elastic compliance to the link, and evaluate the characteristics of variable stiffness soft inflatable links. The detailed investigation of the dynamic behaviour of inflatable link takes into consideration different internal pressures and applied loads. Our results demonstrate that the use of soft inflatable links leads to good weight lifting capability whilst preserving compliance which is beneficial for safety critical applications
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