250 research outputs found
Growth diagram of La0.7Sr0.3MnO3 thin films using pulsed laser deposition
An experimental study was conducted on controlling the growth mode of
La0.7Sr0.3MnO3 thin films on SrTiO3 substrates using pulsed laser deposition
(PLD) by tuning growth temperature, pressure and laser fluence. Different thin
film morphology, crystallinity and stoichiometry have been observed depending
on growth parameters. To understand the microscopic origin, the adatom
nucleation, step advance processes and their relationship to film growth were
theoretically analyzed and a growth diagram was constructed. Three boundaries
between highly and poorly crystallized growth, 2D and 3D growth, stoichiometric
and non-stoichiometric growth were identified in the growth diagram. A good fit
of our experimental observation with the growth diagram was found. This case
study demonstrates that a more comprehensive understanding of the growth mode
in PLD is possible
Exploring scale invariance in the expansion of a spherical unitary Fermi gas
A unitary Fermi gas in an isotropic harmonic trap is predicted to show scale
and conformal symmetry that have important consequences in its thermodynamic
and dynamical properties. By experimentally realizing an isotropic harmonic
trap, we study the expansion of a unitary Fermi gas and demonstrate its
universal expansion dynamics along different directions and at different
temperatures. We show that as a consequence of SO(2,1) symmetry, the measured
release energy is equal to that of the trapping energy. In addition, away from
resonance when scale invariance is broken, we determine the effective exponent
that relates the chemical potential and average density along the
BEC-BCS crossover, which qualitatively agrees with the mean field predictions.
This work opens the possibility of studying non-equilibrium dynamics in a
conformal invariant system in the future.Comment: 15 pages and 8 figur
Mechanism of the Quorum-Quenching Lactonase (AiiA) from Bacillus thuringiensis. 2. Substrate Modeling and Active Site Mutations†
Phylogenetic studies of sinipercid fish (Perciformes: Sinipercidae) based on multiple genes, with first application of an immune-related gene, the virus-induced protein (viperin) gene
The sinipercid fish represent a group of 12 species of freshwater percoid fish endemic to East Asia. To date published morphological and molecular phylogenetics hypotheses of sinipercid fish are part congruent, and there are some areas of significant disagreement with respect to species relationships. The present study used separate and combined methods to analyze 7307 bp of data from three mitochondrial genes (cyt b, CO1 and 16S rRNA; approximate to 2312 bp) and three nuclear genes (viperin, the first two introns of S7 ribosomal protein gene; approximate to 4995 bp) for the attempts to estimate the relationships among sinipercids and to assess the phylogenetic utility of these markers. Phylogenetic trees were reconstructed using maximum parsimony, maximum likelihood and partitioned Bayesian analyses. Despite the detection of significant heterogeneity of phylogenetic signal between the mitochondrial and nuclear partitions, the combined data analysis represented the best-supported topology of all data. The sinipercid fish form a monophyletic group with two distinct clades, one corresponding to the genus Siniperca and the other to Coreoperca. Coreoperca whiteheadi is the sister taxon to Coreoperca herzi plus Coreoperca kawamebari. In the Siniperca, Siniperca undulata is the sister taxon to the other members of Siniperca, within the subclade containing the other members of the genus, Siniperca chuatsi and Siniperca kneri are sister species, next joined by Siniperca obscura, Siniperca roulei, Siniperca scherzeri and finally by Siniperca fortis. The potential utilities of six different genes for phylogenetic resolution of closely related sinipercid species were also evaluated, with special interest in that of the novel virus-induced protein (viperin) gene. (C) 2010 Elsevier Inc. All rights reserved
Growth diagram of La0.7Sr0.3MnO3 thin films using pulsed laser deposition
An experimental study was conducted on controlling the growth mode of La0.7Sr0.3MnO3 thin films on SrTiO3 substrates using pulsed laser deposition (PLD) by tuning growth temperature, pressure, and laser fluence. Different thin film morphology, crystallinity, and stoichiometry have been observed depending on growth parameters. To understand the microscopic origin, the adatom nucleation, step advance processes, and their relationship to film growth were theoretically analyzed and a growth diagram was constructed. Three boundaries between highly and poorly crystallized growth, 2D and 3D growth, stoichiometric and non-stoichiometric growth were identified in the growth diagram. A good fit of our experimental observation with the growth diagram was found. This case study demonstrates that a more comprehensive understanding of the growth mode in PLD is possible
Designing forest biodiversity experiments : general considerations illustrated by a new large experiment in subtropical China
Funded by German Research Foundation. Grant Number: DFG FOR 891/1 and 2 National Natural Science Foundation of China. Grant Numbers: NSFC 30710103907, 30930005, 31170457 , 31210103910 Swiss National Science Foundation (SNSF) Sino-German Centre for Research Promotion in BeijingPeer reviewedPublisher PD
Active control of magnetoresistance of organic spin valves using ferroelectricity
Organic spintronic devices have been appealing because of the long spin life
time of the charge carriers in the organic materials and their low cost,
flexibility and chemical diversity. In previous studies, the control of
resistance of organic spin valves is generally achieved by the alignment of the
magnetization directions of the two ferromagnetic electrodes, generating
magnetoresistance.1 Here we employ a new knob to tune the resistance of organic
spin valves by adding a thin ferroelectric interfacial layer between the
ferromagnetic electrode and the organic spacer. We show that the resistance can
be controlled by not only the spin alignment of the two ferromagnetic
electrodes, but also by the electric polarization of the interfacial
ferroelectric layer: the MR of the spin valve depends strongly on the history
of the bias voltage which is correlated with the polarization of the
ferroelectric layer; the MR even changes sign when the electric polarization of
the ferroelectric layer is reversed. This new tunability can be understood in
terms of the change of relative energy level alignment between ferromagnetic
electrode and the organic spacer caused by the electric dipole moment of the
ferroelectric layer. These findings enable active control of resistance using
both electric and magnetic fields, opening up possibility for multi-state
organic spin valves and shed light on the mechanism of the spin transport in
organic spin valves
MeJA regulates the accumulation of baicalein and other 4’-hydroxyflavones during the hollowed root development in Scutellaria baicalensis
The dried roots of Scutellaria baicalensis are important traditional Chinese medicine used to treat liver and lung inflammation. An anomalous structure, hollowed root, was discovered in perennial cultivated Scutellaria baicalensis. The presence of the hollow may change the contents of bioactive metabolites, such as baicalein, and other 4’-hydroxyflavones in Scutellaria baicalensis roots, but the relationship between the hollowed root and bioactive metabolite contents is poorly understood. In this study, we identified the anatomical structure of the hollowed root and detected differentially accumulating flavonoid metabolites and enzymes related to 4’-hydroxyflavone biosynthesis in 3-year-old roots with a hollow. We confirmed that methyl jasmonate (MeJA) induced the accumulation of 4’-hydroxyflavones and the expression of enzymes related to 4’-hydroxyflavone biosynthesis in hydroponically cultured Scutellaria baicalensis roots. The development of the hollowed root were divided into 4 stages. The 4’-hydroxyflavone contents and expression of enzymes related to 4’-hydroxyflavone biosynthesis increased synchronously with the content of MeJA during the development of hollowed root. Pathogen and programed-cell-death related genes were induced during hollowed root development. Taken together, our results provide novel insight into the importance of MeJA in the development of hollowed root and the accumulation of 4’-hydroxyflavones in Scutellaria baicalensis roots. Our results suggest that a pathogen and senescence are the two major causes for the development of hollowed root in Scutellaria baicalensis roots
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