High‑precision directional and localized membrane poration on a single
cell surface by laser‑generated tandem microbubble
The collapse of two laser‑generated microbubbles is controlled with high
precision to produce directional microjets and associated microstreaming
and vortices in the surrounding fluid that can open up
transiently nano‑ to micro‑meter pores on a cell surface nearby.
Cavitation (i.e., bubble formation and oscillation induced by ultrasound
or laser) plays a vital role in many therapeutic applications. Yet, the
exact mechanism of action is not completely known. Researchers at Duke
University have now developed a novel method to investigate cavitation
bubble‑cell interaction at single cell level in a microfluidics channel
that can capture, for the first time, the entire process of
bubble‑jet‑cell interaction with pin‑point opening of cell membrane and
subsequent progressive diffusion of macromolecules into the target
cell. This method has great potential in directional and localized
gene, siRNA and drug delivery to single cells with a diverse range of
applications in bioengineering, drug screening and lab‑on‑a‑chip
devices, as well as in basic studies to better understand the mechanisms
of cavitation‑induced bioeffects.
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ER10715
Contactless pumping of magnetic fluids
Medical drugs can be attached to magnetic particles. Magnetic fluids are
made from magnetic particles, and can be manipulated without touching
them by applying magnetic fields. In this paper we describe a new method
of continuosly pumping a magnetic liquid, using a periodically modulated
magnetic field. In this way, a flow can be maintained inside a closed
system, where moving components are not wanted or not possible. To
improve the efficiency by more than an order of magnitude, we make use
of a surface instability. Although the resulting pressure is far below
one bar, it is sufficient to drive for example some microfluidic devices
or lab‑on‑a‑chip applications. By utilizing our pumping mechanism, these
devices can be sealed from the ambient, which would be a requirement for
health care applications. Our publication points out the physics that
makes the pump work.
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LR12478
Twisting Space‑Time by Relativistic Mechanism: Origin of Cosmic Magnetic
Field and Vorticity
The universe is filled with "vortexes" (such as galaxies, accretion disks,
stars and planetary systems, etc.) that clump and wind‑up with magnetic
fields. Strikingly absent in this rich narrative of growth and evolution of
the cosmic systems, is a satisfactory "universal" mechanism that could have
generated the original seed magnetic field. Because the explosive expansion
of the universe must immensely dilute the magnetic field strength, very
strong fields must have originated in the early universe. Exploiting the
space‑time distortion inherent in relativistic dynamics, we have unearthed
just the mechanism that, by breaking the topological constraint forbidding
the emergence of magnetic fields (vortexes), allows "general vorticities"
‑‑naturally coupled vortexes of matter motion and magnetic fields‑‑ to be
created in an ideal fluid. The newly postulated relativistic mechanism,
arising from the interaction between the inhomogeneous flow fields and
inhomogeneous entropy, may be an attractive universal solution to the
origin problem.
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LT12743
Visualizing quantum effects in jellium with x‑rays
It has already been known for a century that electrons in metals can
only be described correctly by using quantum mechanics. However, until
now an accurate measurement of the underlying quantum state has proved
extremely challenging. In this article, we report how the extremely
bright x‑rays from a synchrotron light source can provide information
on how electrons correlate with each other in jellium, the simplest
type of electron gas.
Electrons are elementary particles obeying Fermi statistics, meaning
that each one must behave slightly differently from the others. This
property is directly reflected in the electron distribution as a
discontinuity at the so‑called Fermi surface. We report the first
quantitative experiment measuring the magnitude of this discontinuity
in jellium and compare the experimental value with the most accurate
theoretical predictions available. The study gives important
information for understanding electron correlation effects, which are
believed to play a key role in most of the unanswered questions in
condensed matter physics today, such as high‑temperature
superconductivity.
***
LG12460
1/f noise found optimal for information transport.
1/f noise, also known as pink noise or flicker noise, is often referred to as ubiquitous in nature.
Since its first discovery in semiconductor diodes it is in fact been found in numerous physical, biological, socio-economical complex systems, from electron devices to internet traffic.
It is characterized by its spectral properties, it is increasingly stronger at lower frequencies differently from the more common uniform white noise.
Why is it so widespread in nature?
Much work has been devoted to pinpoint the universal character of 1/f-noise,
in this paper we analyse the information transport properties of 1/f signals in the context of renewal processes and show that the ideal condition of 1/f noise corresponds to maximal information transmission rate.
More precisely we show that complex networks generating 1/f noise, known to be insensitive to harmonic perturbations, respond instead to similar 1/f-type stimuli and we argue that adaptive complex networks might therefore naturally be led to the ideal 1/f noise condition by optimization of shared information.
