97 research outputs found
Efficient resistive memory effect on SrTiO3 by ionic-bombardment
SrTiO3 is known to exhibit resistive memory effect either with cation-doping
or with high-temperature thermal reduction. Here, we add another scheme,
ionic-bombardment, to the list of tools to create resistive memory effect on
SrTiO3 (STO). In an Ar-bombarded STO crystal, two orders of resistance
difference was observed between the high and low resistive states, which is an
order of magnitude larger than those achieved by the conventional thermal
reduction process. One of the advantages of this new scheme is that it can be
easily combined with lithographic processes to create spatially-selective
memory effect.Comment: 14 pages, 4 figure
Sr flux stability against oxidation in oxide-MBE environment: flux, geometry, and pressure dependence
Maintaining stable fluxes for multiple source elements is a challenging task
when the source materials have significantly different oxygen affinities in a
complex-oxide molecular-beam-epitaxy (MBE) environment. Considering that Sr is
one of the most easily oxidized and widely used element in various complex
oxides, we took Sr as a probe to investigate the flux stability problem in a
number of different conditions. Source oxidation was less for higher flux,
extended port geometry, and un-melted source shape. The extended port geometry
also eliminated the flux transient after opening a source shutter as observed
in the standard port. We also found that the source oxidation occurred more
easily on the crucible wall than on the surface of the source material. Atomic
oxygen, in spite of its stronger oxidation effectiveness, did not make any
difference in source oxidation as compared to molecular oxygen in this
geometry. Our results may provide a guide for solutions to the source oxidation
problem in oxide-MBE system.Comment: 22 pages, 7 figure
Development of a new urban climate model based on the model PALM – Project overview, planned work, and first achievements
In this article we outline the model development planned within the joint project Model-based city planning
and application in climate change (MOSAIK). The MOSAIK project is funded by the German Federal
Ministry of Education and Research (BMBF) within the framework Urban Climate Under Change ([UC]2)
since 2016. The aim of MOSAIK is to develop a highly-efficient, modern, and high-resolution urban climate
model that allows to be applied for building-resolving simulations of large cities such as Berlin (Germany).
The new urban climate model will be based on the well-established large-eddy simulation code PALM, which
already has numerous features related to this goal, such as an option for prescribing Cartesian obstacles. In
this article we will outline those components that will be added or modified in the framework of MOSAIK.
Moreover, we will discuss the everlasting issue of acquisition of suitable geographical information as input
data and the underlying requirements from the model’s perspective
A stability analysis of a real space split operator method for the Klein-Gordon equation
We carry out a stability analysis for the real space split operator method
for the propagation of the time-dependent Klein-Gordon equation that has been
proposed Ruf et al. [M. Ruf, H. Bauke, C.H. Keitel, A real space split operator
method for the Klein-Gordon equation, Journal of Computational Physics 228 (24)
(2009) 9092-9106, doi:10.1016/j.jcp.2009.09.012]. The region of algebraic
stability is determined analytically by means of a von-Neumann stability
analysis for systems with homogeneous scalar and vector potentials. Algebraic
stability implies convergence ofthe real space split operator method for smooth
absolutely integrable initial conditions. In the limit of small spatial grid
spacings in each of the spatial dimensions and small temporal steps
, the stability condition becomes for second order
finite differences and for fourth order finite
differences, respectively, with denoting the speed of light. Furthermore,
we demonstrate numerically that the stability region for systems with
inhomogeneous potentials coincides almost with the region of algebraic
stability for homogeneous potentials
Altered Backbone and Side-Chain Interactions Result in Route Heterogeneity during the Folding of Interleukin-1b (IL-1b)
Deletion of the b-bulge trigger-loop results in both a switch in the preferred folding route, from the functional loop
packing folding route to barrel closure, as well as conversion of the agonist activity of IL-1b into antagonist activity. Conversely,
circular permutations of IL-1b conserve the functional folding route as well as the agonist activity. These two extremes in the
folding-functional interplay beg the question of whether mutations in IL-1b would result in changes in the populations of heterogeneous
folding routes and the signaling activity. A series of topologically equivalent water-mediated b-strand bridging interactions
within the pseudosymmetric b-trefoil fold of IL-1b highlight the backbone water interactions that stabilize the secondary and
tertiary structure of the protein. Additionally, conserved aromatic residues lining the central cavity appear to be essential for both
stability and folding. Here, we probe these protein backbone-water molecule and side chain-side chain interactions and the role
they play in the folding mechanism of this geometrically stressed molecule. We used folding simulations with structure-based
models, as well as a series of folding kinetic experiments to examine the effects of the F42W core mutation on the folding landscape
of IL-1b. This mutation alters water-mediated backbone interactions essential for maintaining the trefoil fold. Our results
clearly indicate that this perturbation in the primary structure alters a structural water interaction and consequently modulates the
population of folding routes accessed during folding and signaling activity
- …