3,666 research outputs found
Fabrication and Optical Behaviors of Core–Shell ZnS Nanostructures
Novel core–shell nanostructures comprised of cubic sphalerite and hexagonal wurtzite ZnS have been synthesized at 150°C by a simple hydrothermal method. The results of HR-TEM and SAED investigation reveal that the cores of hexagonal wurtzite ZnS (ca. 200 nm in average diameter) are encapsulated by a shell of cubic sphalerite ZnS. The FE-SEM image of the nanomaterials shows a surface tightly packed with nanoparticles (<10 nm in size). The optical properties of the fabricated material have been studied in terms of ultraviolet–visible absorption and photoluminescence. Furthermore, a possible mechanism for the fabrication of the core–shell nanostructures has been presented
Tunable Semiconductors: Control over Carrier States and Excitations in Layered Hybrid Organic-Inorganic Perovskites
For a class of 2D hybrid organic-inorganic perovskite semiconductors based on
-conjugated organic cations, we predict quantitatively how varying the
organic and inorganic component allows control over the nature, energy and
localization of carrier states in a quantum-well-like fashion. Our
first-principles predictions, based on large-scale hybrid density-functional
theory with spin-orbit coupling, show that the interface between the organic
and inorganic parts within a single hybrid can be modulated systematically,
enabling us to select between different type-I and type-II energy level
alignments. Energy levels, recombination properties and transport behavior of
electrons and holes thus become tunable by choosing specific organic
functionalizations and juxtaposing them with suitable inorganic components
Model-Independent Determination of and using Time-Delay Galaxy Lenses and Gamma-Ray Bursts
Combining the `time-delay distance' () measurements from galaxy
lenses and other distance indicators provides model-independent determinations
of the Hubble constant () and spatial curvature (), only
based on the validity of the Friedmann-Lema\^itre-Robertson-Walker (FLRW)
metric and geometrical optics. To take the full merit of combining measurements in constraining , we use gamma-ray burst (GRB) distances
to extend the redshift coverage of lensing systems much higher than that of
Type Ia Supernovae (SNe Ia) and even higher than quasars, whilst the general
cosmography with a curvature component is implemented for the GRB distance
parametrizations. Combining Lensing+GRB yields ~km
sMpc and (1). A
flat-universe prior gives slightly an improved ~km
sMpc. When combining Lensing+GRB+SN Ia, the error bar falls by 25\%, whereas is not improved due to the
degeneracy between SN Ia absolute magnitude, , and along with the
mismatch between the SN Ia and GRB Hubble diagrams at . Future
increment of GRB observations can help to moderately eliminate the
degeneracy in SN Ia distances and ameliorate the restrictions on cosmographic
parameters along with when combining Lensing+SN Ia+GRB. We
conclude that there is no evidence of significant deviation from a (an) flat
(accelerating) universe and is currently determined at 3\% precision. The
measurements show great potential to arbitrate the tension between the
local distance ladder and cosmic microwave background measurements and provide
a relevant consistency test of the FLRW metric.Comment: Accepted for publication in MNRA
Methods for labeling error detection in microarrays based on the effect of data perturbation on the regression model
Abstract
Motivation: Mislabeled samples often appear in gene expression profile because of the similarity of different sub-type of disease and the subjective misdiagnosis. The mislabeled samples deteriorate supervised learning procedures. The LOOE-sensitivity algorithm is an approach for mislabeled sample detection for microarray based on data perturbation. However, the failure of measuring the perturbing effect makes the LOOE-sensitivity algorithm a poor performance. The purpose of this article is to design a novel detection method for mislabeled samples of microarray, which could take advantage of the measuring effect of data perturbations.
Results: To measure the effect of data perturbation, we define an index named perturbing influence value (PIV), based on the support vector machine (SVM) regression model. The Column Algorithm (CAPIV), Row Algorithm (RAPIV) and progressive Row Algorithm (PRAPIV) based on the PIV value are proposed to detect the mislabeled samples. Experimental results obtained by using six artificial datasets and five microarray datasets demonstrate that all proposed methods in this article are superior to LOOE-sensitivity. Moreover, compared with the simple SVM and CL-stability, the PRAPIV algorithm shows an increase in precision and high recall.
Availability: The program and source code (in JAVA) are publicly available at http://ccst.jlu.edu.cn/CSBG/PIVS/index.htm
Contact: [email protected]; [email protected]
Draft Genome Sequence of Gordonia lacunae BS2T
We report here the draft genome sequence of the soil bacterium Gordonia
lacunae BS2T ( DSM 45085T JCM 14873T NRRL B-24551T), isolated from
an estuary in Plettenberg Bay, South Africa. Analysis of the draft genome revealed
that more than 40% of the secondary metabolite biosynthetic genes encode new
compounds
Exchange-biased hybrid gamma-Fe2O3/NiO core-shell nanostructures:three-step synthesis, microstructure, and magnetic properties
A two-step solvothermal method combining a calcination process was conducted to synthesize gamma-Fe2O3/NiO core-shell nanostructures with controlled microstructure. The formation mechanism of this binary system has been discussed, and the influence of microstructures on magnetic properties has been analyzed in detail. Microstructural characterizations reveal that the NiO shells consisted of many irregular nanosheets with disordered orientations and monocrystalline structures, packed on the surface of the gamma-Fe2O3 microspheres. Both the grain size and NiO content of nanostructures increase with the increasing calcination temperature from 300 degrees C to 400 degrees C, accompanied by an enhancement of the compactness of NiO shells. Magnetic studies indicate that their magnetic properties are determined by four factors: the size effect, NiO phase content, interface microstructure, i.e. contact mode, area, roughness and compactness, and FM-AFM (where FM and AFM denote the ferromagnetic gamma-Fe2O3 and the antiferromagnetic NiO components, respectively) coupling effect. At 5 K, the gamma-Fe2O3/NiO core-shell nanostructures display certain exchange bias (H-E = 60 Oe) and enhanced coercivity (H-C = 213 Oe)
Final State Interactions in
It is believed that the production rate of is almost
solely determined by final state interactions (FSI) and hence provides an ideal
place to test FSI models. Here we examine model calculations of the
contributions from s-channel resonance and t-channel exchange to
the FSI effects in . The contribution from s-channel
is sma The results from
two methods are roughly consistent with each other and can reproduce the large
rate of reasonably well$Comment: Latex, 16 pages, with 2 figure
- …