448 research outputs found
Simulation of Piezoelectric Laminated Smart Structure under Strong Electric Field
Applying strong electric field on piezoelectric actuators,
on one hand very significant electroelastic material nonlinear effects
will occur, on the other hand piezo plates and shells may undergo
large displacements and rotations. In order to give a precise
prediction of piezolaminated smart structures under large electric
field, this paper develops a finite element (FE) model accounting for
both electroelastic material nonlinearity and geometric nonlinearity
with large rotations based on the first order shear deformation
(FSOD) hypothesis. The proposed FE model is applied to analyze
a piezolaminated semicircular shell structure
Motorized Macrocycle:A Photo-responsive Host with Switchable and Stereoselective Guest Recognition
Designing photo-responsive host–guest systems can provide versatile supramolecular tools for constructing smart systems and materials. We designed photo-responsive macrocyclic hosts, modulated by light-driven molecular rotary motors enabling switchable chiral guest recognition. The intramolecular cyclization of the two arms of a first-generation molecular motor with flexible oligoethylene glycol chains of different lengths resulted in crown-ether-like macrocycles with intrinsic motor function. The octaethylene glycol linkage enables the successful unidirectional rotation of molecular motors, simultaneously allowing the 1:1 host–guest interaction with ammonium salt guests. The binding affinity and stereoselectivity of the motorized macrocycle can be reversibly modulated, owing to the multi-state light-driven switching of geometry and helicity of the molecular motors. This approach provides an attractive strategy to construct stimuli-responsive host–guest systems and dynamic materials
8-(2,2,2-TrifluoroÂethoxy)quinolinium perchlorate–8-(2,2,2-trifluoroÂethoxy)quinoline (1/1)
The title compound, C11H9F3NO+·ClO4
−·C11H8F3NO or [(C11H8F3NO)H(C11H8F3NO)]ClO4, contains two 8-(2,2,2-trifluoroÂethÂÂoxy)quinoline molecules, one of which combines a proton from perchloric acid to form the corresponding quinolinium cation. The quinolinium and quinoline rings form a cationic unit via an interÂmolecular N—H⋯N hydrogen bond. The heterocyclic units are almost perpendicular to each other [interÂplanar angle 86.97 (6)°]. In the crystal, each perchlorate anion bridges two adjacent cationic units and creates a chain by a combination of C—H⋯O hydrogen bonds. Two inversion-related chains associate into a molÂecular column by π–π stacking interÂactions between the quinolinium rings. The perpendicular and centroid–centroid distances between adjacent quinolinium rings are 3.501 (3) and 3.634 (9) Å, respectively. The molecular column is linked to its neighbors, creating a two-dimensional network via the weak π–π stacking between the quinoline rings [perpendicular and centroid–centroid separations 3.340 (4) and 4.408 (4) Å, respectively]. Finally, a three-dimensional framework is formed by a combination of intermolecular C—F⋯π contacts. One –CF3 group is disordered over two positions of equal occupancy
CLDN5 affects lncRNAs acting as ceRNA dynamics contributing to regulating blood-brain barrier permeability in tumor brain metastasis
The blood‑brain barrier (BBB) constitutes an efficient organization of tight junctions that limits the delivery of tumor to the brain. The principal tight junction protein in BBB is claudin‑5 (CLDN5), but its mechanism of action remains largely unknown. Long non‑coding RNAs (lncRNAs) are aberrantly expressed in many cancers, some lncRNAs play key roles in regulating BBB permeability and are involved in tumor brain metastasis. In particular, lncRNAs can function as competing endogenous RNAs (ceRNAs). Herein, we investigated whether ceRNA dysregulation is associated with alterations of the level of CLDN5 in human brain vascular endothelial hCMEC/D3 cells. The Affymetrix Human Transcriptome Array 2.0 and Affymetrix GeneChip miRNA 4.0 Array were used to detect the expression levels of 2,578 miRNAs, 22,829 lncRNAs, and 44,699 mRNAs in pLL3.7‑CLDN5‑transfected and pLL3.7 control hCMEC/D3 cells. The distinctly expressed miRNAs, lncRNAs, and mRNAs were subjected to construction of miRNA‑lncRNA‑mRNA interaction network. A total of 41 miRNAs, 954 lncRNAs, and 222 mRNAs were found to be differentially expressed between the CLDN5‑overexpressing and control group. 148 lncRNA acting as ceRNAs were identified based on the miRNA‑lncRNA‑mRNA interaction network. The function of differential mRNA in the network was determined by GO and pathway analysis. The potential roles of the 27 ceRNAs were revealed, the possible biology functions of these regulatory ceRNAs mainly included tight junction, focal adhesion, cell‑cell adhesion, cell growth and apoptosis. The identified sets of miRNAs, lncRNAs and mRNAs specific to CLDN5‑overexpressing hCMEC/D3 cells were verified by quantitative real‑time RT‑PCR experiment. Our study predicts the biological functions of a multitude of ceRNAs associated with the alteration of CLDN5 in brain vascular endothelial cells. Our data suggest that these dysregulated ceRNAs, in conjunction with the high CLDN5 levels, could serve as useful targets of prevention of brain metastasis formation. Further studies are warranted to determine the role of these ceRNAs in facilitating the function of CLDN5 in brain‑tumor barrier
Multicolor Photometry Study of the Galaxy Cluster A2589: Dynamics, Luminosity Function and Star Formation History
In this paper we present a multicolor photometry for A2589 () with
15 intermediate bands in the Beijing-Arizona-Taiwan-Connecticut (BATC) system
which covers an optical wavelength range from 3000 \AA\ to 10000 \AA. The
spectral energy distributions (SEDs) for more than 5000 sources are achieved
down to {\it V} 20 mag in about 1 deg field. A2589 has been also
covered by the Sloan Digital Sky Survey (SDSS) in photometric mode only. A
cross-identification of the BATC-detected galaxies with the SDSS photometric
catalog achieves 1199 galaxies brighter than mag, among which 68
member galaxies with known spectroscopic redshifts are found. After combining
the SDSS five-band photometric data and the BATC SEDs, the technique of
photometric redshift is applied to these galaxies for selecting faint member
galaxies. The color-magnitude relation is taken as a further restriction of
early-type cluster galaxies. As a result, 106 galaxies are newly selected as
member galaxies. Spatial distribution of member galaxies shows a north-south
elongation which agrees with the X-ray brightness profile and the orientation
of central cD galaxy, NGC 7647. No substructures are detected on the basis of
positions and radial velocities of cluster galaxies, indicating that A2589 is a
well-relaxed system. The luminosity function of A2589 exhibits a peak at mag and a dip at mag. The low-density outer regions
are the preferred habitat of faint galaxies. With the evolutionary population
synthesis model, PEGASE, the environmental effect on the star formation
properties for 68 spectroscopically confirmed member galaxies is studied. The
outlier faint galaxies tend to have longer time scales of star formation,
shorter mean stellar ages, and lower metallicities of interstellar medium,
which can be interpreted in the context of hierarchical cosmological scenario.Comment: 2011 Accepted to A
Superconductivity in SmFe1-xMxAsO (M = Co, Rh, Ir)
In this paper we report the comparative study of superconductivity by 3d
(Co), 4d (Rh), 5d (Ir) element doping in SmFeAsO. X-ray diffraction patterns
indicate that the material has formed the ZrCuSiAs-type structure with a space
group P4/nmm. It is found that the antiferromagnetic spin-density-wave (SDW)
order in the parent compounds is rapidly suppressed by Co, Rh, and Ir doping,
and superconductivity emerges. Both electrical resistance and magnetization
measurements show superconductivity up to around 10 K in SmFe1-xMxAsO (M = Co,
Rh, Ir). Co, Rh and Ir locate in the same column in the periodic table of
elements but have different electronic band structure, so comparative study
would add more ingredients to the underlying physics of the iron-based
superconductors.Comment: 16 pages, 4 figures, 1 tabl
DA5-CH, a novel GLP-1/GIP dual agonist, effectively ameliorates the cognitive impairments and pathology in the APP/PS1 mouse model of Alzheimer's disease
Alzheimer's disease (AD) is a progressive neurodegenerative disorder for which there is no cure. The early primary symptom of AD is the decline of memory ability, which gradually develops into complete dementia. Type 2 diabetes mellitus (T2DM) is an important risk factor of AD; and mimetics of the incretin hormone GLP-1 developed to treat diabetes are being tested as a novel therapeutic strategy for AD. In the present study, we reported for the first time the neuroprotective effects of a novel GLP-1/GIP dual agonist DA5-CH that activates the incretin hormone GLP-1 and GIP receptors in the APP/PS1 transgenic AD mouse model. We found that: (1) DA5-CH administration effectively improved working-memory and long-term spatial memory of 9-month-old AD mice in Y-maze and Morris water maze tests; (2) DA5-CH also reduced hippocampal amyloid senile plaques and phosphorylated tau protein levels; (3) DA5-CH basically reversed the deficits in hippocampal late-phase long-term potentiation; (4) DA5-CH up-regulated the levels of p-PI3K and p-AKT growth factor kinases and prevented excessive activation of p-GSK3β in the hippocampus of APP/PS1 mice. Therefore, the neuroprotection of DA5-CH in alleviating cognitive impairments and pathological damages might be associated with the improvement of hippocampal synaptic plasticity and activation of the PI3K/AKT signaling pathway. We propose that DA5-CH may be beneficial for the treatment of AD patients, especially those with T2DM or hyperglycemia
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