Fullerene polymers for batteries and fuel cells
Fuel cells and Li-ion batteries, the energy storage devices for engines
running on non-fossil fuel, rely on the quality of ionic conductors.
Presently, only amorphous or disordered materials possess high enough ion
mobility to be used in these systems. This paper provides unambiguous
experimental evidence for an extraordinarily large ionic conductivity in
Li4C60, a lithium intercalated fullerene polymer. Unlike most other ionic
conductors, this material is crystalline, and the Li ions easily move within
the rigid network of polymeric sheets of C60 molecules. It is demonstrated
that there is a regular arrangement of empty spaces in the polymeric network
that allows a fast diffusion of Li ions at ambient temperatures (see
attached image). The outstanding ionic conductivity of Li4C60 is a first
step towards applying fullerenes in energy storage devices.
***
LZ11553
Metamaterials reveal "new light"
Researchers have experimentally demonstrated the excitation of a new, or
additional optical wave in metamaterials. Light is usually composed of
two beams that differ by their polarization. One of these is called the
"s-" or "TE" wave and the other one the "p-" or "TM" wave. However, it
appears that this simple picture of the world needs to be substantially
changed for at least one class of metamaterials - the nanostructured
composites made from arrays of aligned metallic nanorods (left panel in
figure) that have recently been suggested for negative refraction and
cloaking applications. As shown in the upcoming Letter, in addition to
the "usual" TE wave, the nanorod structure supports not one, but two TM
waves. The implications of this discovery are enormous. First, the
additional wave represents a new information channel that can be used
for communications or for security. Second, the additional wave
drastically changes the refraction in nanorods, as evident from
interference pattern in the right panel in the figure, and may affect
the image formation in the metamaterial lens and cloaking process.
Lastly, the additional wave should be the generic property of the
so-called "epsilon-near-zero" metamaterials, reflecting important
parallels between physics of metamaterials, and physics of
low-temperature crystals.
***
Power and pressure fluctuations in elastic turbulence over a wide range of polymer concentrations
Probability distribution functions of power and pressure fluctuations in a spatially smooth (just a few spatial modes) and random in time flow such as elastic turbulence in polymer solutions in a wide range of polymer concentrations are found to be non-Gaussian, intermittent, and strongly resemble the statistical behavior of these variables in other hydrodynamic systems, such as hydrodynamic turbulence, wave turbulence and turbulent convection, which are in contrast to elastic turbulence exhibit an energy cascade in a wide range of both spatial and temporal modes involved in dynamics. In spite of the similarity in statistical behavior, different physical mechanisms in these turbulent systems are responsible for the intermittency. So based on this finding, it is suggested that there exists a common universal mechanism, which determines the similar intermittent statistics in all hydrodynamic non-equilibrium systems.
***
EA10566
FACING CLUSTERING PROCESSES IN COMPLEX SYSTEMS
Exploring space-time chaos dynamics in a 1D array of thermoconvective oscillators or hotspots allows to understand how a global synchronization transition is reached from an initial state of irregular clusters. Research on complex systems has given rise to an extraordinary variety of space-time cluster phenomena. In nature, for example, we find clusters of synchronized oscillators in biology (from bacteria colonies to the beats of pacemakers cells in the heart), in chemistry (spirals in reaction-diffusion systems), in neurobiology (epileptic activity of neurons) and in physics (coupled arrays of superconductors and semiconductor lasers). Our experiment consists on a 1D array of 80 nonlinearly coupled convective oscillators that are destabilized from a basic multicellular pattern by increasing their temperature. We characterize the way in which the phase synchronization spreads over the array using Fourier demodulation techniques. A weak nonlinear coupling between oscillators enables a synchronization towards a space-time chaos regime of inhomogeneously spread irregular clusters with an average size of 30 mm. For higher values of temperature, these irregular clusters gain space-time coherence undergoing a second order transition towards a space-time beating phenomenon. These beats develops robust coherent domains of 80 mm width with time periodicity of 62 s, as it is shown in the figure. We show that the splitting of the critical space-time frequencies in a narrow band is responsible for this beating regime.
***
LZ11332
Squeezing solids with a flash of light
In this paper, we have used short pulses of x rays to watch how the
atoms of a crystal move away from their average positions after the
bonds that hold the atoms together are suddenly weakened by a short,
intense pulse of laser light. The bond weakening from the light leads
to a "squeezing" of the atomic vibrations in the crystal, since the
atoms are initially closer to their average positions than is normally
allowed. We then watch the atomic vibrations in time as they quickly
oscillate and reach their new values. This is the first demonstration
of squeezing in a solid that has looked directly at the motion of the
atoms. It shows how bright pulses of laser light can drive a solid to
behave very differently from what we would normally expect.
***
BZ10927
Towards fully parameter free simulation of materials properties
In this article, we present a novel theoretical approach to simulate the temperature dependence of materials properties with hitherto not achievable accuracy. This approach represents a major step towards materials design solely on the computer and without any experimental input. Moreover, it can be used to resolve long standing uncertainties about physical mechanisms, which dominate the high-temperature behavior of metals and eventually the transition from the solid to the liquid phase. One of the decisive problems, which remained unresolved for over 90 years, is the detailed balance of contributions to the heat capacity (the amount of heat needed to change a material’s temperature) of a metal (such as, e.g., aluminum) before melting. Our new approach allowed for the first time an accurate quantification of the relevant excitation mechanisms and surprisingly revealed that none of the previously suggested concepts was right.
***
LZ11075
New Kinetic Plasma Equilibria Found
The kinetic version of a family of plasma equilibria has been found,
which so far was only known in the fluid regime. The newly found
equilibria open up new avenues in the investigation of plasma
stability and dynamics, in particular for space and astrophysical
plasmas. In collisionless plasmas magnetic activity processes, e.g.
solar flares, often taken place in current sheets, which are
approximately one-dimensional layers of strongly enhanced electric
current density. The new family of equilibria includes the
well-known Harris sheet, the standard model for a collisionless
current sheet, but also presents for the first time kinetic solutions
for the force-free Harris sheet and all intermediate cases between
the two extremes. Whereas for the Harris sheet the current density is
perpendicular to the magnetic field and force balance is maintained
by the plasma pressure gradient, in the case of the force-free Harris
sheet the current density is parallel to the magnetic field and force
balance is maintained by an additional magnetic field component,
while plasma pressure and density are constant.
***
LZ11494
Two long standing mysteries might be nearing a resolution...
There are a number of long standing mysteries in the fields of physical
chemistry and biophysics. The Hofmeister
effect, which has now been known for over $120$ years is,
perhaps, one of the oldest and most puzzling ones.
Hofmeister observed that
different ions have very different effect on
stability of protein solutions.
A related mystery, which is also very old, has to do with the surface
tensions.
Some hundred years ago
Heydweiller noted that adding a strong electrolyte to water leads to
increase in the
surface tension of the water-air interface.
While the dependence on the type of cation is weak,
there is a strong variation of the excess surface
tension with the type of anion --- the lighter halides lead to
larger excess surface tension than the heavier ones.
Both effects are completely unaccounted for by the current theories
of electrolytes. In this paper a new class of electrolyte models is
introduced.
Unlike the previous approaches, the polarizability of ions are
explicitly taken into account.
Contrary to the classical expectations, the theory predicts that larger
halogen anions are adsorbed at the water-vapor and the water-oil
interfaces, while the alkali metal cations are repelled from it. The
degree of adsorption predicted by the theory is
in accordance with the Hofmeister and Heydweiller effects.
***
LX10962EJ
Revealing the physics hidden behind universalities occurring in
ultra-viscous liquids
The ultra-viscous liquid phase above the glass transition temperature of
super-cooled liquids has several peculiarities, such as the enormous
values of viscosity (about 10^15 of that of ambient water). Experiments
and computer simulations converge to the point that some properties of
this state of matter (often called “solid that flows”)
exhibits universal behavior, independently of the type of the viscous
liquid (for example, different values of dynamic quantities collapse on a
master curve when plotted against some quantities, such as density and
temperature. A physical reasoning why universalities occur was missing
until. A.N. Papathanassiou, in his paper appearing Phys. Rev. E, proved
that when long-standing standard elastic solid-state point defect models
are used to describe the viscous liquid and are combined with fundamental
thermodynamics, density scaling law of diffusivity at various pressures
are obtained, in agreement with recently published results of computer
simulations. Elastic models (according to which the dynamic process are
controlled by the elastic properties of the material) were suspected to
hide behind the peculiar properties of viscous liquids, but it was the
above-mentioned publication that revealed the physics underlying
universalities in a definite way.
***
BA11139
FEAST for eigenvalue problems
The eigenvalue problem arises from a wide range of applications in
sciences and engineering, and it is known as one of the most challenging
numerical processes- also called diagonalization procedure or spectral
decomposition.
Solving eigenvalue problems has been a central topic in numerical linear
algebra for the past decades where powerful tools and numerous numerical
library packages have been developed from Jacobi method and power
iterations to iterative Krylov subspace techniques including Arnoldi and
Lanczos methods or other Davidson-Jacobi techniques. These traditional
numerical algorithms are yet facing new challenges for addressing the
current large-scale simulation needs for ever higher level of
efficiency, accuracy, and scalability in modern parallel architectures.
This paper presents a fast, robust, and scalable algorithm design for
solving the symmetric eigenvalue problem—named FEAST— which deviates
fundamentally from the techniques above and takes its inspiration from
the density-matrix representation and contour integration in quantum
mechanics. FEAST combines simplicity and efficiency, as the main
computational tasks consists of solving few independent linear systems
and one reduced eigenvalue problem order of magnitudes size smaller than
the original one. As presented in particular in the paper, this general
purpose solver is expected to significantly augment numerical
performances and capabilities in modern large-scale electronic structure
calculations
***
EX10328
Combinatorial signals shape cellular patterns
Cells continually have to make logic decisions, many of which are taken through cis-regulatory modules (CRMs).
From viewpoints of evolutionism, these CRMs are changeable, e.g., cis-regulatory mutations, thus leading to
different cellular patterns at different developmental stages. Both deciphering the codes and elucidating
the functions of CRMs involved in various developmental processes are a major challenge in biology and biological
physics. In this paper, we demonstrated that, using computational and mathematical models of synthetic bacterial
genetic oscillators coupled by quorum sensing, different CRMs for integration of both intracellular and
extracellular signals drive fundamentally different cellular patterns, independent of network topology of the
core oscillator. This qualitative result implies that the diversity of CRMs arising possibly from cis-regulatory
mutations can provide a flexible platform for revolutionarily tuning response behaviors for optimal fitness.
As an interesting corollary of our study, the genetic network architecture found in synchronous circadian clocks
is constrained since complete synchronization the circadian clocks display takes place only with a particular CRM.
