27 research outputs found
Solitary waves in the Nonlinear Dirac Equation
In the present work, we consider the existence, stability, and dynamics of
solitary waves in the nonlinear Dirac equation. We start by introducing the
Soler model of self-interacting spinors, and discuss its localized waveforms in
one, two, and three spatial dimensions and the equations they satisfy. We
present the associated explicit solutions in one dimension and numerically
obtain their analogues in higher dimensions. The stability is subsequently
discussed from a theoretical perspective and then complemented with numerical
computations. Finally, the dynamics of the solutions is explored and compared
to its non-relativistic analogue, which is the nonlinear Schr{\"o}dinger
equation. A few special topics are also explored, including the discrete
variant of the nonlinear Dirac equation and its solitary wave properties, as
well as the PT-symmetric variant of the model
In Vitro and in Vivo Visualization and Trapping of Fluorescent Magnetic Microcapsules in a Bloodstream
Remote
navigation and targeted delivery of biologically active compounds
is one of the current challenges in the development of drug delivery
systems. Modern methods of micro- and nanofabrication give us new
opportunities to produce particles and capsules bearing cargo to deploy
and possess magnetic properties to be externally navigated. In this
work we explore multilayer composite magnetic microcapsules as targeted
delivery systems in vitro and in vivo studies under natural conditions
of living organism. Herein, we demonstrate magnetic addressing of
fluorescent composite microcapsules with embedded magnetite nanoparticles
in blood flow environment. First, the visualization and capture of
the capsules at the defined blood flow by the magnetic field are shown
in vitro in an artificial glass capillary employing a wide-field fluorescence
microscope. Afterward, the capsules are visualized and successfully
trapped in vivo into externally exposed rat mesentery microvessels.
Histological analysis shows that capsules infiltrate small mesenteric
vessels whereas large vessels preserve the blood microcirculation.
The effect of the magnetic field on capsule preferential localization
in bifurcation areas of vasculature, including capsule retention at
the site once external magnet is switched off is discussed. The research
outcome demonstrates that microcapsules can be effectively addressed
in a blood flow, which makes them a promising delivery system with
remote navigation by the magnetic field