Interface-Engineered NiFe/Ni-S Nanoparticles for Reliable Alkaline Oxygen Production at Industrial Current: A Sulfur Source Confinement Strategy.

Using powder-based ink appears to be the most suitable candidate for commercializing the membrane electrode assembly (MEA), while research on the powder-based NPM catalyst for anion exchange membrane water electrolyzer (AEMWE) is currently insufficient, especially at high current density. Herein, a sulfur source (NiFe Layered double hydroxide adsorbed SO 4 2 - ${\mathrm{SO}}_4^{2 - }$ ) confinement strategy is developed to integrate Ni3 S2 onto the surface of amorphous/crystalline NiFe alloy nanoparticles (denoted NiFe/Ni-S), achieving advanced control over the sulfidation process for the formation of metal sulfides. The constructed interface under the sulfur source confinement strategy generates abundant active sites that increase electron transport at the electrode-electrolyte interface and improve ability over an extended period at a high current density. Consequently, the constructed NiFe/Ni-S delivers an ultra-low overpotential of 239 mV at 10 mA cm-2 and 0.66 mA cm ECSA - 2 ${\mathrm{cm}}_{{\mathrm{ECSA}}}^{ - 2}$ under an overpotential of 300 mV. The AEMWE with NiFe/Ni-S anode exhibits a cell voltage of 1.664 V @ 0.5 A cm-2 and a 400 h stability at 1.0 A cm-2 .

Defect-Engineered ZIF-Derived Non-Pt Cathode Catalyst at 1.5 mg cm-2 Loading for Proton Exchange Membrane Fuel Cells.

Due to the sluggish kinetics of the oxygen reduction reaction (ORR) by non-Pt based catalyst, high loading of catalyst is required to achieve satisfactory fuel cell performance, which inevitably leads to the increase of the catalyst layer thickness with serious mass transport resistance. Herein, a defective zeolitic imidazolate framework (ZIF) derived Co/Fe-N-C catalyst with small mesopores (2-4 nm) and high density of CoFe atomic active sites are prepared by regulating the Fe dosage and pyrolysis temperature. Molecular dynamics simulation and electrochemical tests indicate that > 2 nm mesopores show insignificant influence on the diffusion process of O2 and H2 O molecules, leading to the high utilization of active sites and low mass transport resistance. The proton exchange membrane fuel cell (PEMFC) shows a high-power density of 755 mW cm-2 with only 1.5 mg cm-2 of non-Pt catalyst in the cathode. No apparent performance loss caused by concentration difference can be observed, in particular in the high current density region (1 A cm-2 ). This work emphasizes the importance of small mesopore design in the Co/Fe-N-C catalyst, which is anticipated to provide essential guidance for the application of non-Pt catalysts.

Treatment of basilar artery stenosis with an Apollo balloon-expandable stent: a single-centre experience with 61 consecutive cases.

Stent placement for basilar artery (BA) stenosis remains a technical and clinical challenge. This retrospective study introduces the experience with the Apollo balloon-expandable stent (BES) for patients with symptomatic BA stenosis in a single centre in China. Sixty one patients who had undergone intervention for severe symptomatic BA stenosis between May 2012 and September 2018 were enrolled in this study. All patients underwent angioplasty and stenting with an Apollo BES and were followed-up continuously. The technical success rate was 100%. During the procedure, there was no vessel rupture or dissection. Two patients died due to perforator occlusion. One patient developed vasospasm with no symptoms. The rate of complications during the procedure was 4.91% (3/61). BA stent-related stroke or death rates were 4.9% at 30 days (3/61), 6.6% at 3 months (4/61), and 6.6% (4/61) at 6 months. One patient had stent occlusion at 6 months with no symptoms. Restenosis was found in five patients with degrees of restenosis greater than ≥ 50% without any symptoms. In this study, the Apollo BES appeared to be feasible for BA stenosis. Our experience may be valuable for reducing the number of complications. However, further study is needed.

Using operando techniques to understand and design high performance and stable alkaline membrane fuel cells.

There is a need to understand the water dynamics of alkaline membrane fuel cells under various operating conditions to create electrodes that enable high performance and stable, long-term operation. Here we show, via operando neutron imaging and operando micro X-ray computed tomography, visualizations of the spatial and temporal distribution of liquid water in operating cells. We provide direct evidence for liquid water accumulation at the anode, which causes severe ionomer swelling and performance loss, as well as cell dryout from undesirably low water content in the cathode. We observe that the operating conditions leading to the highest power density during polarization are not generally the conditions that allow for long-term stable operation. This observation leads to new catalyst layer designs and gas diffusion layers. This study reports alkaline membrane fuel cells that can be operated continuously for over 1000 h at 600 mA cm-2 with voltage decay rate of only 32-µV h-1 - the best-reported durability to date.

Nitrogen-doped Carbon-CoOx Nanohybrids: A Precious Metal Free Cathode that Exceeds 1.0†W cm-2 Peak Power and 100†h Life in Anion-Exchange Membrane Fuel Cells.

Efficient and durable nonprecious metal electrocatalysts for the oxygen reduction (ORR) are highly desirable for several electrochemical devices, including anion exchange membrane fuel cells (AEMFCs). Here, a 2D planar electrocatalyst with CoOx embedded in nitrogen-doped graphitic carbon (N-C-CoOx ) was created through the direct pyrolysis of a metal-organic complex with a NaCl template. The N-C-CoOx catalyst showed high ORR activity, indicated by excellent half-wave (0.84 V vs. RHE) and onset (1.01 V vs. RHE) potentials. This high intrinsic activity was also observed in operating AEMFCs where the kinetic current was 100 mA cm-2 at 0.85 V. When paired with a radiation-grafted ETFE powder ionomer, the N-C-CoOx AEMFC cathode was able to achieve extremely high peak power density (1.05 W cm-2 ) and mass transport limited current (3 A cm-2 ) for a precious metal free electrode. The N-C-CoOx cathode also showed good stability over 100 hours of operation with a voltage decay of only 15 % at 600 mA cm-2 under H2 /air (CO2 -free) reacting gas feeds. The N-C-CoOx cathode catalyst was also paired with a very low loading PtRu/C anode catalyst, to create AEMFCs with a total PGM loading of only 0.10 mgPt-Ru cm-2 capable of achieving 7.4 W mg-1 PGM as well as supporting a current of 0.7 A cm-2 at 0.6 V with H2 /air (CO2 free)-creating a cell that was able to meet the 2019 U.S. Department of Energy initial performance target of 0.6 V at 0.6 A cm-2 under H2 /air with a PGM loading <0.125 mg cm-2 with AEMFCs for the first time.

The first anion-exchange membrane fuel cell to exceed 1 W cm-2 at 70 °C with a non-Pt-group (O2) cathode.

Anion-exchange membrane fuel cells face two challenges: performance and durability. Addressing the first, we demonstrate high performance with both O2 and CO2-free air supplies, even when using a Ag/C cathode. This was enabled by the development of a radiation-grafted anion-exchange membrane that was less than 30 µm thick when hydrated.

Preparation and in vitro evaluation of an acidic environment-responsive liposome for paclitaxel tumor targeting.

Paclitaxel (PTX) is an important cancer chemotherapeutic drug. To ameliorate the disadvantages of paclitaxel, this study designed liposomes to load paclitaxel, adding the acid-sensitive material cholesteryl hemisuccinate (CHEMS) to increase the accumulation of the drug in the tumor site. To begin, we used a high-performance liquid chromatography (HPLC) method to determine the content of PTX and the encapsulation efficiency. Then, we prepared paclitaxel-loaded acid-sensitive liposomes (PTX ASLs) by a thin-film dispersion method. We investigated the physical and chemical properties of the liposomes. The particle size was 210.8 nm, the polydispersity index (PDI) was 0.182 and the ζ-potential was -31.2 mV. The liposome shape was observed by transmission electron microscopy (TEM), and the results showed that the liposomes were round with a homogenous size distribution. The release characteristics of the liposomes in vitro were studied via a dynamic dialysis method. The results showed that the prepared liposomes had acid sensitivity and sustained release properties. An in vitro cellular uptake assay of MCF-7 cells showed that the cell uptake of coumarin-6-loaded acid-sensitive liposomes was significantly higher than that of free coumarin-6. The cytotoxicity of the PTX ASLs was significantly higher than that of paclitaxel. In conclusion, these results showed that the prepared liposomes had clear acid-sensitive release characteristics and a higher cell uptake rate and cytotoxicity than free PTX. The system is very suitable for targeted cancer therapy with paclitaxel.

Direct alcohol fuel cells: toward the power densities of hydrogen-fed proton exchange membrane fuel cells.

A 2 µm thick layer of TiO2 nanotube arrays was prepared on the surface of the Ti fibers of a nonwoven web electrode. After it was doped with Pd nanoparticles (1.5 mgPd cm(-2) ), this anode was employed in a direct alcohol fuel cell. Peak power densities of 210, 170, and 160 mW cm(-2) at 80 °C were produced if the cell was fed with 10 wt % aqueous solutions of ethanol, ethylene glycol, and glycerol, respectively, in 2 M aqueous KOH. The Pd loading of the anode was increased to 6 mg cm(-2) by combining four single electrodes to produce a maximum peak power density with ethanol at 80 °C of 335 mW cm(-2) . Such high power densities result from a combination of the open 3 D structure of the anode electrode and the high electrochemically active surface area of the Pd catalyst, which promote very fast kinetics for alcohol electro-oxidation. The peak power and current densities obtained with ethanol at 80 °C approach the output of H2 -fed proton exchange membrane fuel cells.

Electrooxidation of ethylene glycol and glycerol on Pd-(Ni-Zn)/C anodes in direct alcohol fuel cells.

The electrooxidation of ethylene glycol (EG) and glycerol (G) has been studied: in alkaline media, in passive as well as active direct ethylene glycol fuel cells (DEGFCs), and in direct glycerol fuel cells (DGFCs) containing Pd-(Ni-Zn)/C as an anode electrocatalyst, that is, Pd nanoparticles supported on a Ni-Zn phase. For comparison, an anode electrocatalyst containing Pd nanoparticles (Pd/C) has been also investigated. The oxidation of EG and G has primarily been investigated in half cells. The results obtained have highlighted the excellent electrocatalytic activity of Pd-(Ni-Zn)/C in terms of peak current density, which is as high as 3300 A g(Pd)(-1) for EG and 2150 A g(Pd)(-1) for G. Membrane-electrode assemblies (MEA) have been fabricated using Pd-(Ni-Zn)/C anodes, proprietary Fe-Co/C cathodes, and Tokuyama A-201 anion-exchange membranes. The MEA performance has been evaluated in either passive or active cells fed with aqueous solutions of 5 wt % EG and 5 wt % G. In view of the peak-power densities obtained in the temperature range from 20 to 80 °C, at Pd loadings as low as 1 mg cm(-2) at the anode, these results show that Pd-(Ni-Zn)/C can be classified amongst the best performing electrocatalysts ever reported for EG and G oxidation.

In vivo evaluation of silybin nanosuspensions targeting liver.

The present study investigated the production, in vivo biodistribution and hepatoprotective of two formulated silybin nanosuspensions with different particle size. The physicochemical properties of the two formulated silybin nanosuspensions were investigated by TEM, AFM and SEM. A kinetic study was conducted to evaluate the influence of particle size on the in vivo tissue distribution following intravenous administration in the mice. The in vivo hepatoprotective studies were conducted on beagle dogs with optimized setting. A clear physicochemical difference was observed among the silybin solution, larger particles and the small particles. The formulation of larger particle size was preferentially targeted at liver and spleen. The silybin nanosuspensions, administrated either intravenously or orally, presented significant (P < or = 0.05) hepatoprotective effect by reducing the serum marker enzymes such as AST, ALT, ALP, TBIL and GGT. Histopathological study further confirmed the hepatoprotective activity of the two silybin nanosuspensions formulations when compared with the CCl4 treated control group. These results indicate that the nanosuspensions approaches could be used to improve the drug target delivery and therapeutic efficacy of the silybin.

In situ FTIR spectroelectrochemical study on the mechanism of ethylene glycol electrocatalytic oxidation at a Pd electrode.

The adsorption and electrooxidation pathways of ethylene glycol (EG) on polycrystalline palladium surfaces have been investigated in both alkaline and acidic media by in situ FTIR spectroscopy in conjunction with cyclic voltammetry. Palladium exhibits a high electrocatalytic activity in alkaline solution with low onset oxidation potentials and high current densities, depending on the pH, as well as on the supporting electrolyte. Higher potentials are required for EG oxidation in acidic solutions, where the catalytic performance decreases with increasing the pH. The products and intermediates of EG oxidation on Pd are influenced by the pH. In alkaline media, both C(2) species (glycolate, glyoxal, glyoxylate and oxalate) and C(1) species (formate and carbonate) are formed in mutual concentrations depending on the pH. In contrast, CO(2) is selectively produced in acidic aqueous solution.