10,756 research outputs found
The effect of asymmetry of the coil block on self-assembly in ABC coil-rod-coil triblock copolymers
Using the self-consistent field approach, the effect of asymmetry of the coil
block on the microphase separation is focused in ABC coil-rod-coil triblock
copolymers. For different fractions of the rod block , some stable
structures are observed, i.e., lamellae, cylinders, gyroid, and core-shell
hexagonal lattice, and the phase diagrams are constructed. The calculated
results show that the effect of the coil block fraction is
dependent on . When , the effect of asymmetry of
the coil block is similar to that of the ABC flexible triblock copolymers; When
, the self-assembly of ABC coil-rod-coil triblock copolymers
behaves like rod-coil diblock copolymers under some condition. When continues to increase, the effect of asymmetry of the coil block reduces.
For , under the symmetrical and rather asymmetrical
conditions, an increase in the interaction parameter between different
components leads to different transitions between cylinders and lamellae. The
results indicate some remarkable effect of the chain architecture on
self-assembly, and can provide the guidance for the design and synthesis of
copolymer materials.Comment: 9 pages, 3 figure
Effect of polymer concentration and length of hydrophobic end block on the unimer-micelle transition broadness in amphiphilic ABA symmetric triblock copolymer solutions
The effects of the length of each hydrophobic end block N_{st} and polymer
concentration \bar{\phi}_{P} on the transition broadness in amphiphilic ABA
symmetric triblock copolymer solutions are studied using the self-consistent
field lattice model. When the system is cooled, micelles are observed, i.e.,the
homogenous solution (unimer)-micelle transition occurs. When N_{st} is
increased, at fixed \bar{\phi}_{P}, micelles occur at higher temperature, and
the temperature-dependent range of micellar aggregation and half-width of
specific heat peak for unimer-micelle transition increase monotonously.
Compared with associative polymers, it is found that the magnitude of the
transition broadness is determined by the ratio of hydrophobic to hydrophilic
blocks, instead of chain length. When \bar{\phi}_{P} is decreased, given a
large N_{st}, the temperature-dependent range of micellar aggregation and
half-width of specific heat peak initially decease, and then remain nearly
constant. It is shown that the transition broadness is concerned with the
changes of the relative magnitudes of the eductions of nonstickers and solvents
from micellar cores.Comment: 8 pages, 4 figure
Note on TTˉ deformed matrix models and JT supergravity duals
In this work we calculate the partition functions of type 0A and 0B JT supergravity (SJT) on 2D surfaces of arbitrary genus with multiple finite cut-off boundaries, based on the deformed super-Schwarzian theories. In terms of SJT/matrix model duality, we compute the corresponding correlation functions in the deformed matrix model side by using topological recursion relations as well as the transformation properties of topological recursion relations under deformation. We check that the partition functions finite cut-off 0A and 0B SJT on generic 2D surfaces match the associated correlation functions in deformed matrix models respectively
microRNA-10b enhances pancreatic cancer cell invasion by suppressing TIP30 expression and promoting EGF and TGF-β actions
Increased microRNA-10b (miR-10b) expression in the cancer cells in pancreatic ductal adenocarcinoma (PDAC) is a marker of disease aggressiveness. In the present study, we determined that plasma miR-10b levels are significantly increased in PDAC patients by comparison with normal controls. By gene profiling, we identified potential targets downregulated by miR-10b, including Tat-interacting protein 30 (TIP30). Immunoblotting and luciferase reporter assays confirmed that TIP30 was a direct miR-10b target. Downregulation of TIP30 by miR-10b or siRNA-mediated silencing of TIP30 enhanced epidermal growth factor (EGF)-dependent invasion. The actions of miR-10b were abrogated by expressing a modified TIP30 cDNA resistant to miR-10b. EGF-induced EGF receptor (EGFR) tyrosine phosphorylation and extracellular signal–regulated kinase phosphorylation were enhanced by miR-10b, and these effects were mimicked by TIP30 silencing. The actions of EGF in the presence of miR-10b were blocked by EGFR kinase inhibition with erlotinib and by dual inhibition of PI3K (phosphatidylinositol 3′-kinase) and MEK. Moreover, miR-10b, EGF and transforming growth factor-beta (TGF-β) combined to markedly increase cell invasion, and this effect was blocked by the combination of erlotinib and SB505124, a type I TGF-β receptor inhibitor. miR-10b also enhanced the stimulatory effects of EGF and TGF-β on cell migration and epithelial–mesenchymal transition (EMT) and decreased the expression of RAP2A, EPHB2, KLF4 and NF1. Moreover, miR-10b overexpression accelerated pancreatic cancer cell (PCC) proliferation and tumor growth in an orthotopic model. Thus, plasma miR-10b levels may serve as a diagnostic marker in PDAC, whereas intra-tumoral miR-10b promotes PCC proliferation and invasion by suppressing TIP30, which enhances EGFR signaling, facilitates EGF–TGF-β cross-talk and enhances the expression of EMT-promoting genes, whereas decreasing the expression of several metastasis-suppressing genes. Therefore, therapeutic targeting of miR-10b in PDAC may interrupt growth-promoting deleterious EGF–TGF-β interactions and antagonize the metastatic process at various levels
Mitigate data skew caused stragglers through ImKP partition in MapReduce
Speculative execution is the mechanism adopted by current MapReduce framework when dealing with the straggler problem, and it functions through creating redundant copies for identified stragglers. The result of the quicker task will be adopted to improve the overall job execution performance. Although proved to be effective for contention caused stragglers, speculative execution can easily meet its bottleneck when mitigating data skew caused stragglers due to its replication nature: the identical unbalanced input data will lead to a slow speculative task. The Map inputs are typically even in size according to the HDFS block configuration, therefore the skew caused stragglers happen mainly in the Reduce phase because of the unknown intermediate key distribution. In this paper, we focus on mitigating data skew caused Reduce stragglers, propose ImKP, an Intermediate Key Pre-processing framework that enables the even distributed partition for Reduce inputs. A group based ranking technique has been developed that dramatically decreases the pre-processing time, and ImKP manages to eliminate this timing overhead through parallelizing the pre-processing with the file uploading procedure (from local file system to HDFS). For jobs that take input directly from HDFS, ImKP minimizes the overhead by storing the mapping result on every node within the cluster for reuse. Experiments are conducted on different datasets with various workloads. Results show that, compared to the popular hash partition, ImKP can dramatically decrease Reduce skew, achieving a 99.8% reduction in the coefficient of variation of the input sizes in average, and improve up to 29.37% job response performance
A self-reconstructed bifunctional electrocatalyst of pseudo-amorphous nickel carbide @ iron oxide network for seawater splitting.
Here, a sol-gel method is used to prepare a Prussian blue analogue (NiFe-PBA) precursor with a 2D network, which is further annealed to an Fe3 O4 /NiCx composite (NiFe-PBA-gel-cal), inheriting the ultrahigh specific surface area of the parent structure. When the composite is used as both anode and cathode catalyst for overall water splitting, it requires low voltages of 1.57 and 1.66 V to provide a current density of 100 mA cm-2 in alkaline freshwater and simulated seawater, respectively, exhibiting no obvious attenuation over a 50 h test. Operando Raman spectroscopy and X-ray photoelectron spectroscopy indicate that NiOOH2-x active species containing high-valence Ni3+ /Ni4+ are in situ generated from NiCx during the water oxidation. Density functional theory calculations combined with ligand field theory reveal that the role of high valence states of Ni is to trigger the production of localized O 2p electron holes, acting as electrophilic centers for the activation of redox reactions for oxygen evolution reaction. After hydrogen evolution reaction, a series of ex situ and in situ investigations indicate the reduction from Fe3+ to Fe2+ and the evolution of Ni(OH)2 are the origin of the high activity
The information about the state of a qubit gained by a weakly coupled detector
We analyze the information that one can learn about the state of a quantum
two-level system, i.e. a qubit, when probed weakly by a nearby detector. In
particular, we focus on the case when the qubit Hamiltonian and the qubit's
operator being probed by the detector do not commute. Because the qubit's state
keeps evolving while being probed and because the measurement data is mixed
with a detector-related background noise, one might expect the detector to fail
in this case. We show, however, that under suitable conditions and by proper
analysis of the measurement data useful information about the state of the
qubit can be extracted. It turns out that the measurement basis is
stochastically determined every time the experiment is repeated. We analyze in
detail the probability distributions that govern the choice of measurement
bases. We also analyze the information acquisition rate and show that it is
largely unaffected by the apparent conflict between the measurement and
intrinsic qubit dynamics. We discuss the relation between our analysis and the
stochastic master equation that describes the evolution of the qubit's state
under the influence of measurement and decoherence. In particular, we write
down a stochastic equation that encompasses the usual stochastic master
equation for the evolution of the qubit's density matrix and additionally
contains the measurement information that can be extracted from the observed
signal.Comment: 21 pages (two column), 8 figure
Vortex Glass and Vortex Liquid in Oscillatory Media
We study the disordered, multi-spiral solutions of two-dimensional
homogeneous oscillatory media for parameter values at which the single
spiral/vortex solution is fully stable. In the framework of the complex
Ginzburg-Landau (CGLE) equation, we show that these states, heretofore believed
to be static, actually evolve on ultra-slow timescales. This is achieved via a
reduction of the CGLE to the evolution of the sole vortex position and phase
coordinates. This true defect-mediated turbulence occurs in two distinct
phases, a vortex liquid characterized by normal diffusion of individual
spirals, and a slowly relaxing, intermittent, ``vortex glass''.Comment: 4 pages, 2 figures, submitted to Physical Review Letter
Spiral Motion in a Noisy Complex Ginzburg-Landau Equation
The response of spiral waves to external perturbations in a stable regime of
the two-dimensional complex Ginzburg-Landau equation (CGLE) is investigated. It
is shown that the spiral core has a finite mobility and performs Brownian
motion when driven by white noise. Combined with simulation results, this
suggests that defect-free and quasi-frozen states in the noiseless CGLE are
unstable against free vortex excitation at any non-zero noise strength.Comment: RevTex, 4 pages, 3 figures, submitted to Phys. Rev. Let
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