Z. Y. Liu

The effect of a layer-by-layer chitosan-heparin coating on the endothelialization and coagulation properties of a coronary stent system

A biomacromolecular layer-by-layer coating process of chitosan/heparin onto a coronary stent is designed for the acceleration of the re-endothelialization and healing process after coronary stent deployment. The results of in vitro culturing of porcine iliac artery endothelial cells as well as the measurements of the APTT, PT and TT supported the rationale that the combination of chitosan and heparin could bring both endothelial cell compatibility and haemocompatibility to the stent surface. A porcine coronary injury model and arteriovenous shunt model were used for the further evaluation of the application of this kind of surface-modified stainless steel stent in vivo. The final results proved that this facile coating approach could significantly promote re-endothelialization and was safer compared with bare metal stents for its much improved anticoagulation property.

REstoration of COronary flow in patients with no-reflow after primary coronary interVEntion of acute myocaRdial infarction (RECOVER)

BACKGROUND No randomized trial has been conducted to compare different vasodilators for treating no-reflow during primary percutaneous coronary intervention (PCI) for ST-segment elevation acute myocardial infarction. METHODS The prospective, randomized, 2-center trial was designed to compare the effect of 3 different vasodilators on coronary no-reflow. A total of 102 patients with no-reflow in primary PCI were randomized to receive intracoronary infusion of diltiazem, verapamil, or nitroglycerin (n = 34 in each group) through selective microcatheter. The primary end point was coronary flow improvement in corrected thrombolysis in myocardial infarction frame count (CTFC) after administration of the drug. RESULTS Compared with that of the nitroglycerin group, there was a significant improvement of CTFC after drug infusion in the diltiazem and verapamil groups (42.4 frames vs 28.1 and 28.4 frames, P < .001). The improvement in CTFC was similar between the diltiazem and verapamil groups (P = .9). Compared with the nitroglycerin group, the diltiazem and verapamil groups had more complete ST-segment resolution at 3 hours after PCI, lower peak troponin T level, and lower N-terminal pro-B-type natriuretic peptide levels at 1 and 30 days after PCI. After drug infusion, the drop of heart rate and systolic blood pressure in the verapamil group was greater than that in the diltiazem and nitroglycerin groups. CONCLUSION Intracoronary infusion of diltiazem or verapamil can reverse no-reflow more effectively than nitroglycerin during primary PCI for acute myocardial infarction. The efficacy of diltiazem and verapamil is similar, and diltiazem seems safer.

Flux pinning of stress-induced magnetic inhomogeneity in the bilayers of YBa2Cu3O7−δ/La0.67Sr0.33MnO3−δ

Elaborately designed bilayers consisting of epitaxial YBa2Cu3O7−δ (YBCO) and La0.67Sr0.33MnO3−δ (LSMO) films were fabricated by pulsed laser deposition with respect to the investigation into magnetic-dependent vortex pinning effect. The improvement in the critical current density and a pronounced upward shift in the superconducting irreversibility line based on magnetotransport measurements are observed when compared to the pure YBCO film, suggesting the enhancement in flux pinning in the studied bilayer. It is believed that the improved flux pinning for YBCO arises from the magnetic inhomogeneity of the underlying LSMO. Magnetization measurements show a nonuniform magnetic state in the LSMO film, most probably being macroscopically phase-separated clusters with ferromagnetic (FM) and anti-FM domains, which can be caused by the epitaxial strain due to the lattice mismatch. Such a magnetic disorder is hardly affected by the external magnetic field, unlike the magnetic disorder induced by the domain structu...

Surface texture and interior residual stress variation induced by thickness of YBa2Cu3O7-δ thin films

YBa2Cu3O7-δ (YBCO) thin films with various thicknesses from 80 nm to 2000 nm are prepared on single crystal SrTiO3 by means of pulsed laser deposition technique. While it is hard for the x-ray diffraction to observe the evolutions in epitaxial orientation and interior lattice structure, the atomic force microscope shows the degraded surface morphologies and coalesced particles which arise from more misoriented grains with increasing thin film thickness. A detailed Raman spectrum investigation reveals that the a-axis grains exist predominately at the top surface of the films as the total thickness of the film increases up to 2000 nm. It is also evident that the Raman peak corresponding to the O2+/O3− mode emerges with the redshift first and then the blueshift as the film thickness increases. These Raman shifts suggest that the tensile stress in the (a, b) plane arising from the lattice mismatch between the epitaxial film and substrate may release gradually with increasing the film thickness, while the addi...

Studies on a Novel Multi-sensitive Hydrogel: Influence of the Biomimetic Phosphorylcholine End-Groups on the PEO–PPO–PEO Tri-block Co-polymers

In the present study, a biomimetic phosphorylcholine group was employed in the end-capping modification of PEO–PPO–PEO tri-block co-polymers (Pluronic®). The structures of the resulting materials were characterized by 1H-NMR and GPC. The effects of the additional phosphorylcholine end-groups to the thermo-sensitive sol–gel transition behaviors of the aqueous solutions of the resulting polymers were studied by rheology test in neutral (0.1 M NaCl) aqueous solutions and in acidic solutions (pH 3). It was found that the phosphorylcholine-end-capped Pluronic hydrogels still kept their thermo-sensitive mechanical properties with a slight change on the sol–gel transition behaviors. The phosphorylcholine-modified Pluronics exhibited a response to the change of the pH value, which made this kind of material a multi-sensitive hydrogel system. Also, the resulting polymers showed improved hemocompatibilities in the blood coagulation test using full human blood.

Robust high-temperature magnetic pinning induced by proximity in YBa2Cu3O7−δ/La0.67Sr0.33MnO3 hybrids

An elaborately designed bilayer consisting of superconducting YBa2Cu3O7−δ (YBCO) and ferromagnetic La0.67Sr0.33MnO3−δ (LSMO) was prepared on a single crystal LaAlO3 substrate by pulsed laser deposition (PLD), with a view to understanding the mechanism behind the influence of superconductor/ferromagnet proximity on the critical current density, Jc. The present bilayer system shows significant modifications in Jc, as evidenced by the suppressed decay of its temperature dependence, as well as the crossing behavior of the magnetic field dependence of Jc at high temperatures. This indicates that enhanced flux pinning emerges at high temperatures, and it is believed to arise from the special magnetic inhomogeneity, i.e., the ferromagnet/antiferromagnet clusters caused by phase separation due to the epitaxial stress between LSMO and the substrate.

Enhanced conversion efficiency in dye-sensitized solar cells with nanocomposite photoanodes

Nanocomposite architectures consisting of conductive carbon nanotubes (CNTs) and nanocrystalline TiO2 films are prepared as photoanodes of dye-sensitized solar cells (DSCs). It is observed that both the electron transport time and electron lifetime decrease with CNT addition, implying that its incorporation is effective in enhancing the electro-conductivity of mesoscopic TiO2 contacts. To rectify CNT orientations, a parallel electric field is applied during the sample preparation, which gives rise to a significant enhancement in the energy conversion efficiency of resultant DSCs. Electrochemical impedance spectroscopy clarifies the photoelectrochemical processes, with enhanced contribution to the efficient electron transport, arising from the increased CNT orientation.

Steady-state transport characteristics of photoconductor based on dye-sensitized solar cell

In the present work, three photoconductors based on dye-sensitized nanocrystalline TiO2 are designed with two dye-sensitized solar cells (DSSCs) connected together using a common counter electrode but different connecting approaches for electrolytes and TiO2 film. DC steady-state transport measurements on source and drain corresponding to the photoanodes of two constituent DSSC units, respectively, show that the three photoconductive devices exhibit similar transistor characteristics, regardless of their different electronic connecting approaches. It is revealed that their transport characteristics are determined by the effective areas of the photoanode and the counter electrode, rather than the connection of electrolytes and TiO2 film. Furthermore, it is demonstrated that the dominant factor of transport behavior is the imbalanced energy band caused by the match of intrinsic potential within two constituent DSSC units. Due to unique mechanism and relatively simple fabrication process, the present phototr...

Artificial Multilayers of REBaCuO/YBaCuO and YBCO/CuO(Y2O3) for High-Performance Long Tapes of Coated Conductors Derived by Metal Organic Solution Deposition

Thick superconducting multilayer architectures consisting of alternate superconducting and superconducting layers DyBCO/YBCO and alternate superconducting and insulating layers YBCO/CuO(Y₂O₃) are developed on buffered Hastelloy tapes using a metal organic deposition process. It is revealed that multilayer intermittent structures for superconducting layers are effective to avoid the presence of microcracks that occur with increasing thickness, which are frequently observed in monolayer films of REBa₂Cu₃O_7−δ (REBCO, RE = Y, Gd, or other rare earth elements). This paper shows that the thicknesses of DyBCO/YBCO multilayer films can reach 2.8 μm with a homogeneous, dense and crack-free surface morphology. The out-plane FWHM of the YBCO (005) peaks and the critical current value reach 1.1° and 365 A/cm (77 K, self-field) for such a thick film consisting of DyBCO/YBCO multilayers. It is also revealed that the introduction of a CuO layer is effective to avoid the presence of a-axis grains and voids of the YBCO films, which are frequently observed in multilayer films. Note that the introduction of CuO shows little negative influence on the texture of multilayer structure, especially for the bottom CuO. However, the in-plane texture deteriorates seriously for Y₂O₃/YBCO/YBCO multilayer film. The critical current density of YBCO films with middle CuO and bottom CuO are 2.0 MA/cm² and 2.5 MA/cm² (77 K, self-field), respectively. The microstructure optimization including the texture, uniformity, crack, defect, and porosity in the multilayered films is probably the reason for the enhancement of superconducting performance.

Efficacy and safety of renal denervation for Chinese patients with resistant hypertension using a microirrigated catheter: study design and protocol for a prospective multicentre randomised controlled trial

Introduction Available data show that approximately 8%–18% of patients with primary hypertension will develop resistant hypertension. In recent years, catheter-based renal denervation (RDN) has emerged as a potential treatment option for resistant hypertension. A number of observational studies and randomised controlled trials among non-Chinese patients have demonstrated its potential safety and efficacy. Methods and analysis This is a multicentre, randomised, open-label, parallel-group, active controlled trial that will investigate the efficacy and safety of a 5F saline-irrigated radiofrequency ablation (RFA) used for RDN in the treatment of Chinese patients with resistant hypertension. A total of 254 patients who have failed pharmacological therapy will be enrolled. Eligible subjects will be randomised in a 1:1 ratio to undergo RDN using the RFA plus antihypertensive medication or to receive treatment with antihypertensive medication alone. The primary outcome measure is the change in 24 hours average ambulatory systolic blood pressure from baseline to 3 months, comparing the RDN-plus-medication group with the medication-alone group. Important secondary endpoints include the change in office blood pressure from baseline to 6 months after randomisation. Safety endpoints such as changes in renal function will also be evaluated. The full analysis set, according to the intent-to-treat principle, will be established as the primary analysis population. Ethics and dissemination All participants will provide informed consent; the study protocol has been approved by the Independent Ethics Committee for each site. This study is designed to investigate the efficacy and safety of RDN using a 5F saline microirrigated RFA. Findings will be shared with participating hospitals, policymakers and the academic community to promote the clinical management of resistant hypertension in China. Trial registration ClinicalTrials.gov ID: NCT02900729; pre-results.