Coronary stents: a materials perspective.

Nano-scale modification of titanium implant surfaces to enhance osseointegration

Visible-stimulated emission in a semiconductor quantum dot (QD) laser structure has been demonstrated. Red-emitting, self-assembled QDs of highly strained InAlAs have been grown by molecular beam epitaxy on a GaAs substrate. Carriers injected electrically from the doped regions of a separate confinement heterostructure thermalized efficiently into the zero-dimensional QD states, and stimulated emission at ∼707 nanometers was observed at 77 kelvin with a threshold current of 175 milliamperes for a 60-micrometer by 400-micrometer broad area laser. An external efficiency of ∼8.5 percent at low temperature and a peak power greater than 200 milliwatts demonstrate the good size distribution and high gain in these high-quality QDs.

https://science.sciencemag.org/content/sci/274/5291/1350.full.pdf

Red-Emitting Semiconductor Quantum Dot Lasers

We consider a phase field model for the formulation and solution of topology optimization problems in the minimum compliance case. In this model, the optimal topology is obtained as the steady state of the phase transition described by the generalized Cahn–Hilliard equation which naturally embeds the volume constraint on the amount of material available for distribution in the design domain. We reformulate the model as a coupled system and we highlight the dependency of the optimal topologies on dimensionless parameters. We consider Isogeometric Analysis for the spatial approximation which facilitates encapsulating the exactness of the representation of the design domain in the topology optimization and is particularly suitable for the analysis of phase field problems. We demonstrate the validity of the approach and numerical approximation by solving two and three-dimensional topology optimization problems.

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Isogeometric Analysis for Topology Optimization with a Phase Field Model

Realistic finite element-based stent design: the impact of balloon folding.

Analysis of the transient expansion behavior and design optimization of coronary stents by finite element method

Stent expansion in curved vessel and their interactions: a finite element analysis.

Delivery and release of nitinol stent in carotid artery and their interactions: A finite element analysis

The corrosion resistance of TiN and TaN coatings deposited on AISI 316L stainless steel thread-coiled coronary stents by pulsed bias arc ion plating is evaluated by electrochemical methods in deaerated Tyrode's simulated body fluids (37 ± 1 °C). The free corrosion potential of the TaN-coated stents is found to be nobler than that of the TiN-coated and uncoated stents throughout most of the immersion time. The potentiodynamic polarization test results indicate that the TaN coatings offer better passivation stability and anti-breakdown performance. The longer-term 6-month immersion tests disclose slight localized corrosion on the surface of both coatings, but no film delamination or large area pitting can be observed indicating reasonably good corrosion resistance after the long period.

Min Qi

Papers

Analysis of the transient expansion behavior and design optimization of coronary stents by finite element method

Stent expansion in curved vessel and their interactions: a finite element analysis.

Delivery and release of nitinol stent in carotid artery and their interactions: A finite element analysis

Anti-corrosion characteristics of nitride-coated AISI 316L stainless steel coronary stents

Formation and in vitro/in vivo performance of "cortex-like" micro/nano-structured TiO 2 coatings on titanium by micro-arc oxidation