7,700 research outputs found
Topical application of hyaluronic acid-RGD peptide-coated gelatin/epigallocatechin-3 gallate (EGCG) nanoparticles inhibits corneal neovascularization via inhibition of VEGF production
Neovascularization (NV) of the cornea disrupts vision which leads to blindness. Investigation of antiangiogenic, slow-release and biocompatible approaches for treating corneal NV is of great importance. We designed an eye drop formulation containing gelatin/epigallocatechin-3-gallate (EGCG) nanoparticles (NPs) for targeted therapy in corneal NV. Gelatin-EGCG self-assembled NPs with hyaluronic acid (HA) coating on its surface (named GEH) and hyaluronic acid conjugated with arginine-glycine-aspartic acid (RGD) (GEH-RGD) were synthesized. Human umbilical vein endothelial cells (HUVECs) were used to evaluate the antiangiogenic effect of GEH-RGD NPs in vitro. Moreover, a mouse model of chemical corneal cauterization was employed to evaluate the antiangiogenic effects of GEH-RGD NPs in vivo. GEH-RGD NP treatment significantly reduced endothelial cell tube formation and inhibited metalloproteinase (MMP)-2 and MMP-9 activity in HUVECs in vitro. Topical application of GEH-RGD NPs (once daily for a week) significantly attenuated the formation of pathological vessels in the mouse cornea after chemical cauterization. Reduction in both vascular endothelial growth factor (VEGF) and MMP-9 protein in the GEH-RGD NP-treated cauterized corneas was observed. These results confirm the molecular mechanism of the antiangiogenic effect of GEH-RGD NPs in suppressing pathological corneal NV
Precise Particle Tracking Against a Complicated Background: Polynomial Fitting with Gaussian Weight
We present a new particle tracking software algorithm designed to accurately
track the motion of low-contrast particles against a background with large
variations in light levels. The method is based on a polynomial fit of the
intensity around each feature point, weighted by a Gaussian function of the
distance from the centre, and is especially suitable for tracking endogeneous
particles in the cell, imaged with bright field, phase contrast or fluorescence
optical microscopy. Furthermore, the method can simultaneously track particles
of all different sizes, and allows significant freedom in their shape. The
algorithm is evaluated using the quantitative measures of accuracy and
precision of previous authors, using simulated images at variable
signal-to-noise ratios. To these we add a new test of the error due to a
non-uniform background. Finally the tracking of particles in real cell images
is demonstrated. The method is made freely available for non-commencial use as
a software package with a graphical user-inferface, which can be run within the
Matlab programming environment
Peierls barrier characteristic and anomalous strain hardening provoked by dynamic-strain-aging strengthening in a body-centered-cubic high-entropy alloy
The temperature effect on the mechanical behavior of the HfNbTaTiZr high entropy alloy (HEA) was investigated at 77–673 K. The decrease of the yield strength with increasing the temperature was mechanistically analyzed by considering contributions from various strengthening mechanisms. An anomalous dependence of strain hardening on temperature was observed and was justified to be caused by dynamic strain aging (DSA) as an extra strengthening mechanism at elevated temperatures. A model was constructed to split the overall strain hardening into forest hardening and DSA hardening, both of which were theoretically quantified at all temperatures considered.
The work quantifies the height of Peierls barriers in the bcc HfNbTaTiZr HEA, and reveals dynamic strain aging as the strengthening mechanism causing the anomalous strain hardening at elevated temperatures
Contralateral Cerebro-Cerebellar White Matter Pathways for Verbal Working Memory: A Combined Diffusion Spectrum Imaging and fMRI Study
Diffusion spectrum imaging was employed to establish structural connectivity between cerebro-cerebellar regions co-activated during verbal working memory. IFG, IPL, pons, thalamus, superior cerebellum and inferior cerebellum were used as seed points to reconstruct the white matter cerebro-cerebellar circuitry. The reconstructed pathways were examined further to establish the relationship between structural and effective connectivity as well as the relationship between structural connectivity and verbal working memory performance. It was found that structural connectivity is indirectly related to effective connectivity but does not predict it. Additionally, it was demonstrated that the integrity of the ponto-cerebellar tract is an important factor in explaining individual differences in verbal working memory. The findings of the study furthered our understanding of the relationship between structural and functional connectivity and provided insight to the variability in verbal working memory performance
Infrared Spectroscopy of Quantum Crossbars
Infrared (IR) spectroscopy can be used as an important and effective tool for
probing periodic networks of quantum wires or nanotubes (quantum crossbars,
QCB) at finite frequencies far from the Luttinger liquid fixed point. Plasmon
excitations in QCB may be involved in resonance diffraction of incident
electromagnetic waves and in optical absorption in the IR part of the spectrum.
Direct absorption of external electric field in QCB strongly depends on the
direction of the wave vector This results in two types of
dimensional crossover with varying angle of an incident wave or its frequency.
In the case of QCB interacting with semiconductor substrate, capacitive contact
between them does not destroy the Luttinger liquid character of the long wave
QCB excitations. However, the dielectric losses on a substrate surface are
significantly changed due to appearance of additional Landau damping. The
latter is initiated by diffraction processes on QCB superlattice and manifests
itself as strong but narrow absorption peaks lying below the damping region of
an isolated substrate.SubmiComment: Submitted to Phys. Rev.
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