BL11352

Fullerene (C60) Nanowire Polymer

Summary

Two important forms of carbon, fullerene (C60) and carbon nanotubes, are
closely related to each other by the structural commonality of their sp2
frameworks. Carbon nanotubes have been widely investigated for the last
decade or so as one‑dimensional (1D) nanomaterials, but fullerene 1D
nanostructures presently only represent laboratory curiosities. In this
paper, we show the formation of a C60‑based nanowire polymer made by
first growing the coresponding crystalline nanowire through a solution
phase of C60 followed by a topochemical polymerization in the solid
state. This new material is scientifically very interesting and may be
potentially important for nanotechnology because of its low
dimensionality, high surface area, large length‑to‑width ratio,
crystalline and molecularly cross‑linked fullerene‑based nanostructure.
In comparison with carbon nanotubes, fullerene 1D nanopolymers could be
even more attractive in specific electronic and photonic applications
especially for bio‑applications as the material would be bio‑compatible
and totally free from any metal, which clearly contrasts the case of
carbon nanotubes, the growth of which is catalyzed by transition metal
nanoparticles, and from which by no means all the metal can be removed
by a post‑purification process.


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LR12107

Making Ultra-Cold Antimatter

In this article we demonstrate a new technique for obtaining very cold
particles of antimatter. Antimatter is the "mirror image" of the
normal matter that makes up all of the observable universe. The work
took place at CERN in Geneva, Switzerland at the facility that
inspired the popular novel and hit movie "Angels and Demons".
Scientists need cold antimatter atoms in order to perform precision
comparison measurements of matter and antimatter that test the basic
physical laws or symmetries of the universe. The ALPHA collaboration
at CERN adapted a method, called evaporative cooling and commonly used
for obtaining very cold clouds of neutral atoms (Bose‑Einstein
Condensates), to charged antiprotons. The antiproton is the
antimatter equivalent of the proton, which constitutes the nucleus of
Nature's most abundant element, hydrogen. ALPHA scientists study
antihydrogen, which is an atom containing an antiproton and an anti‑
electron, usually called a "positron". To study antimatter,
scientists must store it in high vacuum conditions so that it does not
annihilate with normal matter. ALPHA scientists are hoping to hold on
to their antihydrogen atoms in a device known as an atom trap. For
this to succeed, the antihydrogen atoms must be very close to the
absolute zero point in temperature. The current work demonstrates
that is is possible to cool the antihydrogen nuclei down to about 10
K, by far the lowest temperature ever measured for antiprotons. It is
hoped that the new technique will make it possible for scientists to
trap and study the elusive antihydrogen atoms.

EPJ1042


Maze solving made easy: just follow your nose.

There are many maze solving algorithms. But none as simple as just following your nose. In this paper, it is shown that following your nose will take you through a maze via the shortest possible route to the source of a sweet smelling reward. You will never make a wrong turn. The results neatly explain how nematodes, tiny soil‑dwelling worms, and other creatures can navigate through the labyrinth of air‑filled channels within soils to locate and infest plant roots, causing US$ 70 billion crop losses annually. The predictions are supported by recent experimental studies which have shown that by moving up gradients in acidity, a droplet of organic solvent can find the shortest of multiple possible paths through one particular maze to an acid‑soaked exit. The new results show that nose‑following will work for almost any maze, even fiendishly difficult ones.

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LC12164

Classic gedankenexperiment comes to life in a granular gas

In 1912 Marian Smoluchowski proposed a device with which he argued that it would be possible to create work from a single heat bath or, in other words, to convert heat directly into work. Richard Feynman explained how the laws of thermodynamics forbid Smoluchowski's ratchet to operate at thermal equilibrium. Now, after almost a century, this classic device has been made to work by immersing it in a non-equilibrium environment of vibrated granular particles. The new Smoluchowski-Feynman ratchet is a prototype for a wide variety of biochemical motors on the molecular scale, which play a key role in living organisms by converting chemical energy into work and directed motion. It is also the first ratchet of its sort capable of delivering work continuously.

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LM12523

Synthetic mechanochemical molecular swimmer

The first ever blueprint for a simple synthetic molecular scale swimmer
that converts chemical energy directly into mechanical work via a
built‑in mechanochemical coupling is proposed in this Letter. The
swimming mechanism is based on electrostatic actuation, which is coupled
to the catalytic activity of the two enzymes that form the swimmer. As
technological advances allow us to fabricate smaller and smaller
autonomous self‑propelled devices, it is clear that at some point
directed propulsion could not come from pre‑specified deterministic
periodic deformation of the swimmer's body and we need to develop
strategies to extract a net directed motion from a series of random
transitions in the conformation space of the swimmer.
I use a minimal low Reynolds number swimmer model and electrostatic
interactions as actuation mechanism to induce conformational changes
on the device. The swimmer has two enzymes on board that catalyze
chemical reactions that involve ionic products. When the ions are still
attached to the enzymes, electrostatic interaction between them and
other charged elements of the swimmer can lead to conformational
changes. The design proposes how one can take advantage of these
stochastically temporary charged components of the system and achieve
net propulsion at low Reynolds number.

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LM12230


Poking Holes in Cell Membranes to Make Them Stiffer

During cellular processes, cell membranes undergo various morphological changes that are governed by the interplay between lipid bilayer membranes and proteins. In this paper, we measured for the first time the stiffness of lipid bilayer membranes (mimetic cell membranes) interacting with the pore-forming antimicrobial peptide melittin using neutron spin echo spectroscopy. The measurements revealed three distinct effects on the membrane stiffness as the concentration of melittin was increased. At low melittin concentration, the membrane bending rigidity decreases as individual melittin adsorbs onto the membrane surface, "softening" the membrane. When the melittin concentration is large enough to form pores, the membrane becomes slightly more rigid. At even higher concentrations, additional pores are formed and the inter-pore interactions within the membrane become significant, rapidly “stiffening” the membrane. These findings have improved current understanding of the elastic behavior and morphological changes of cell membranes induced by protein-membrane interactions. In addition, they may guide the development of new theoretical models for membrane fluctuations that include the membrane-mediated interactions between proteins in membrane.

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AQ10509

HOW THE FIRST ATOMS ARRIVED

After the Big Bang that created our Universe about 14 billion years ago
the structure of the Universe was strongly different from the recent
state: there were no atoms, no molecules, no solids. The first simplest
atoms - hydrogen atoms which consist of one proton and one electron
did arrive about 400 000 years after the Big
Bang. This epoch is called the Recombination Epoch. It was not so easy for
the electrons and protons to recombine: jumping down from one atomic level
to another the hydrogen atom released photons which could excite the
neighbouring atom i.e. turn the process back. This could happen many times
and in this way the radiation was coupled to the matter. The radiation
could escape this coupling mainly due to the two-photon
transitions. After this escape the recombination could finally take
place.The astrophysicists now observe this escaped radiation as Cosmic
Microwave Background ( CMB ). In our paper we apply the methods of the
Quantum Electrodynamics to the more accurate description of the
two-photon transitions in the process of cosmological recombination. The
new corrections found in our paper are noticable at the accuracy level of
the recent CMB observations. They may help to understand better the
history of the Early Universe.