661 research outputs found
Assigning Significance in Label-Free Quantitative Proteomics to Include Single-Peptide-Hit Proteins with Low Replicates
When sample replicates are limited in a label-free proteomics experiment, selecting differentially regulated proteins with an assignment of statistical significance remains difficult for proteins with a single-peptide hit or a small fold-change. This paper aims to address this issue. An important component of the approach employed here is to utilize the rule of Minimum number of Permuted Significant Pairings (MPSP) to reduce false positives. The MPSP rule generates permuted sample pairings from limited analytical replicates and simply requires that a differentially regulated protein can be selected only when it is found significant in designated number of permuted sample pairings. Both a power law global error model with a signal-to-noise ratio statistic (PLGEM-STN) and a constant fold-change threshold were initially used to select differentially regulated proteins. But both methods were found not stringent enough to control the false discovery rate to 5% in this study. On the other hand, the combination of the MPSP rule with either of these two methods significantly reduces false positives with little effect on the sensitivity to select differentially regulated proteins including those with a single-peptide hit or with a <2-fold change
Identification of Free and Bound Exciton States and Their Phase-Dependent Trapping Behavior in Lead Halide Perovskites
In this work we probe the sub-gap energy states within polycrystalline and
single crystal lead halide perovskites to better understand their intrinsic
photophysics behaviors. Through combined temperature and intensity-dependent
optical measurements, we reveal the existence of both free and bound exciton
contributions within the sub-gap energy state manifold. The trapping and
recombination dynamics of these excitons is shown to be strongly dependent on
the structural phase of the perovskite. The orthorhombic phase exhibits
ultrafast exciton trapping and distinct trap emission, while the tetragonal
phase gives low monomolecular recombination velocity and capture cross-sections
(~10-18 cm2). Within the multiphonon transition scenario, this suppression in
charge trapping is caused by the increase in the charge capture activation
energy due to the reduction in electron-lattice interactions, which can be the
origin for the unexpected long carrier lifetime in these material systems.Comment: 5 figure
A Digital Watermarking Approach Based on DCT Domain Combining QR Code and Chaotic Theory
This paper proposes a robust watermarking approach based on Discrete Cosine
Transform domain that combines Quick Response Code and chaotic system.Comment: 7 pages, 6 figure
Overexpression of DCF1 Inhibits Glioma through Destruction of Mitochondria and Activation of Apoptosis Pathway
Gliomas are the most common brain tumors affecting the central nervous system and are associated with a high mortality rate. DCF1 is a membrane protein that was previously found to play a role in neural stem cell differentiation. In the present study, we found that overexpression of dcf1 significantly inhibited cell proliferation, migration, and invasion and dramatically promoted apoptosis in the glioblastoma U251 cell line. DCF1 deletion mutations in the functional region showed that the complete structure of DCF1 was necessary for apoptosis. Furthermore, significantly lower tumorigenicity was observed in athymic nude mice by transplanting U251 cells overexpressing dcf1. To decode the apoptosis induced by dcf1, mitochondrial structure and membrane potential in glioma cells were investigated and the results indicated obvious mitochondrial swelling, destruction of cristae, and a significant decline in membrane potential. Mechanismly, caspase-3 signaling was activated. Finally, endogenous dcf1 silence in U251 cells was investigated. Results showed a highly methylation at -1339 and -1322 position at dcf1 promoter sequence, revealing the causal relationship between dcf1 gene and tumorigencicity. The present study identified a previously unknown cancer apoptosis mechanism involving dcf1 overexpression and provided a novel approach to potentially treat glioma patients
Effect of Zn doping on magnetic order and superconductivity in LaFeAsO
We report Zn-doping effect in the parent and F-doped LaFeAsO oxy-arsenides.
Slight Zn doping in LaFeZnAsO drastically suppresses the
resistivity anomaly around 150 K associated with the antiferromagnetic (AFM)
spin density wave (SDW) in the parent compound. The measurements of magnetic
susceptibility and thermopower confirm further the effect of Zn doping on AFM
order. Meanwhile Zn doping does not affect or even enhances the of
LaFeZnAsOF, in contrast to the effect of Zn
doping in high- cuprates. We found that the solubility of Zn content ()
is limited to less than 0.1 in both systems and further Zn doping (i.e.,
0.1) causes phase separation. Our study clearly indicates that the
non-magnetic impurity of Zn ions doped in the FeAs layers
affects selectively the AFM order, and superconductivity remains robust against
the Zn doping in the F-doped superconductors.Comment: 7 figures, 13 pages; revised version with more dat
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