405 research outputs found
Non-specific cellular uptake of surface-functionalized quantum dots
We report a systematic empirical study of nanoparticle internalization into
cells via non-specific pathways. The nanoparticles were comprised of commercial
quantum dots (QDs) that were highly visible under a fluorescence confocal
microscope. Surface-modified QDs with basic biologically-significant moieties,
e.g. carboxyl, amino, streptavidin were used, in combination with the surface
derivatization with polyethylene glycol (PEG) in a range of immortalized cell
lines. Internalization rates were derived from image analysis and a detailed
discussion about the effect of nanoparticle size, charge and surface groups is
presented. We find that PEG-derivatization dramatically suppresses the
non-specific uptake while PEG-free carboxyl and amine functional groups promote
QD internalization. These uptake variations displayed a remarkable consistency
across different cell types. The reported results are important for experiments
concerned with cellular uptake of surface-functionalized nanomaterials, both
when non-specific internalization is undesirable and also when it is intended
for material to be internalized as efficiently as possible.
Published article at: http://iopscience.iop.org/0957-4484/21/28/285105/Comment: 14 pages 7 figure
Beyond scaling and locality in turbulence
An analytic perturbation theory is suggested in order to find finite-size
corrections to the scaling power laws. In the frame of this theory it is shown
that the first order finite-size correction to the scaling power laws has
following form , where
is a finite-size scale (in particular for turbulence, it can be the Kolmogorov
dissipation scale). Using data of laboratory experiments and numerical
simulations it is shown shown that a degenerate case with can
describe turbulence statistics in the near-dissipation range , where
the ordinary (power-law) scaling does not apply. For moderate Reynolds numbers
the degenerate scaling range covers almost the entire range of scales of
velocity structure functions (the log-corrections apply to finite Reynolds
number). Interplay between local and non-local regimes has been considered as a
possible hydrodynamic mechanism providing the basis for the degenerate scaling
of structure functions and extended self-similarity. These results have been
also expanded on passive scalar mixing in turbulence. Overlapping phenomenon
between local and non-local regimes and a relation between position of maximum
of the generalized energy input rate and the actual crossover scale between
these regimes are briefly discussed.Comment: extended versio
Hidden-variable theory versus Copenhagen quantum mechanics
The main assumptions the Copenhagen quantum mechanics has been based on will
be summarized and the known (not yet decided) contradiction between Einstein
and Bohr will be newly analyzed. The given assumptions have been represented
basically by time-dependent Schroedinger equation, to which some further
assumptions have been added. Some critical comments have been raised against
the given mathematical model structure by Pauli (1933) and by Susskind and
Glogover (1964). They may be removed if only the Schroedinger equation is
conserved and the additional assumptions are abandoned, as shown recently. It
seems to be in contradiction to the numerous declarations that the Copenhagen
model has been approved by experimental results.
However, in the most of these experiments only the agreement with the mere
Schroedinger equation has been tested. All mentioned assumptions have been
tested practically only in the EPR experiment (measurement of coincidence light
transmission through two polarizers) proposed originally by Einstein (1935).
Also these experimental results have been interpreted as supporting the
Copenhagen alternative, which has not been, however, true. In fact the
microscopic world may be described correspondingly only with the help of the
hidden-variable theory that is represented by the Schroedinger equation without
mentioned additional assumptions, which has the consequence that the earlier
interpretation gap between microscopic and macroscopic worlds has been removed.
The only difference concerns the existence of discrete states. The
possibilities of the human reason of getting to know the nature will be also
shortly discussed in the beginning of this contribution.Comment: 10 pages, 2 figures; v2: local refinements and improvements of the
tex
Mean- Field Approximation and Extended Self-Similarity in Turbulence
Recent experimental discovery of extended self-similarity (ESS) was one of
the most interesting developments, enabling precise determination of the
scaling exponents of fully developed turbulence. Here we show that the ESS is
consistent with the Navier-Stokes equations, provided the pressure -gradient
contributions are expressed in terms of velocity differences in the mean field
approximation (Yakhot, Phys.Rev. E{\bf 63}, 026307, (2001)). A sufficient
condition for extended self-similarity in a general dynamical systemComment: 8 pages, no figure
The Viscous Lengths in Hydrodynamic Turbulence are Anomalous Scaling Functions
It is shown that the idea that scaling behavior in turbulence is limited by
one outer length and one inner length is untenable. Every n'th order
correlation function of velocity differences \bbox{\cal
F}_n(\B.R_1,\B.R_2,\dots) exhibits its own cross-over length to
dissipative behavior as a function of, say, . This length depends on
{and on the remaining separations} . One result of this Letter
is that when all these separations are of the same order this length scales
like with
, with being
the scaling exponent of the 'th order structure function. We derive a class
of scaling relations including the ``bridge relation" for the scaling exponent
of dissipation fluctuations .Comment: PRL, Submitted. REVTeX, 4 pages, I fig. (not included) PS Source of
the paper with figure avalable at http://lvov.weizmann.ac.il/onlinelist.htm
Scaling law of the plasma turbulence with non conservative fluxes
It is shown that in the presence of anisotropic kinetic dissipation existence
of scale invariant power law spectrum of plasma turbulence is possible.
Obtained scale invariant spectrum is not associated with the constant flux of
any physical quantity. Application of the model to the high frequency part of
the solar wind turbulence is discussed.Comment: Phys Rev E, accepte
The effect of supplements of groundnut flour or groundnut protein isolate fortified with calcium salts and vitamins or of skim-milk powder on the digestibility coefficient, biological value and net utilization of the proteins of poor Indian diets given to undernourished children
This article does not have an abstract
The metabolism of nitrogen, calcium and phosphorus in undernourished children. 8. The metabolism of nitrogen, calcium and phosphorus, and the digestibility coefficient and biological value of the proteins and the net protein utilization on poor Indian diets based on rice, maize or a mixture of rice and maize
This article does not have an abstract
Persistence of small-scale anisotropy of magnetic turbulence as observed in the solar wind
The anisotropy of magnetophydrodynamic turbulence is investigated by using
solar wind data from the Helios 2 spacecraft. We investigate the behaviour of
the complete high-order moment tensors of magnetic field increments and we
compare the usual longitudinal structure functions which have both isotropic
and anisotropic contributions, to the fully anisotropic contribution. Scaling
exponents have been extracted by an interpolation scaling function. Unlike the
usual turbulence in fluid flows, small-scale magnetic fluctuations remain
anisotropic. We discuss the radial dependence of both anisotropy and
intermittency and their relationship.Comment: 7 pages, 2 figures, in press on Europhys. Let
A study of vitamin B<SUB>12</SUB> protection in experimental liver injury to the rat by carbon tetrachloride
This article does not have an abstract
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