and Perspectives Sophie Carenco,†,‡,§,∥,⊥ David Portehault,*,†,‡,§ Ced́ric Boissier̀e,†,‡,§ Nicolas Meźailles, and Cleḿent Sanchez*,†,‡,§ †Chimie de la Matier̀e Condenseé de Paris, UPMC Univ Paris 06, UMR 7574, Colleg̀e de France, 11 Place Marcelin Berthelot, 75231 Paris Cedex 05, France ‡Chimie de la Matier̀e Condenseé de Paris, CNRS, UMR 77574, Colleg̀e de France, 11 Place Marcellin Berthelot, 75231 Paris Cedex 05, France Chimie de la Matier̀e Condenseé de Paris, Colleg̀e de France, 11 Place Marcellin Berthelot, 75231 Paris Cedex 05, France Laboratory Heteroelements and Coordination, Chemistry Department, Ecole Polytechnique, CNRS-UMR 7653, Palaiseau, France

Nanoscaled metal borides and phosphides: recent developments and perspectives

Chemical preparation and characterization of metal–metalloid ultrafine amorphous alloy particles

An extended vapour?liquid?solid (VLS) growth method, which is the reaction of a mixture of nitrogen and ammonia gas over nanoscale Fe?B 'catalyst' particles at 1100??C, has been developed. With this method, BN nanotubes of diameter about 20?nm have been prepared and well characterized by high-resolution transmission electron microscopy and energy dispersive x-ray spectroscopy. In contrast to traditional VLS growth, the boron component in the BN nanotubes comes from the Fe?B 'catalyst' itself, rather than from the vapour precursor. A growing mechanism has been discussed accordingly.

The synthesis of boron nitride nanotubes by an extended vapour?liquid?solid method

Periodic spindle-unit boron nitride (BN) nanotubes with buglelike open-end tips have been found in the product by nitriding Fe-B nanoparticles at 1100 °C with a mixture of nitrogen and ammonia gas. The microstructure was well-characterized by high-resolution transmission electron microscopy (HRTEM) and energy-dispersive X-ray spectroscopy (EDX). The diameter of this BN nanotube shows a decreasing tendency along the growth direction. For each spindle unit, the outer diameter decreases steeply and then increases gradually, accompanied by thinning of the wall thickness along the growth direction. Some spindle units are partially occupied by the iron-containing catalyst particles at the hemispherical-like ends. An improved stress-induced sequential growth model has been reasonably deduced accordingly, with which the formation process of this novel BN nanostructure could be well understood.

Microstructure and Growth Model of Periodic Spindle-Unit BN Nanotubes by Nitriding Fe-B Nanoparticles with Nitrogen/Ammonia Mixture

This paper reviews the advances in the chemical synthesis and application of metal-metalloid amorphous alloy nanoparticles consisting of transition metal (M) and metalloid elements (B, P). After a brief introduction on the history of amorphous alloy catalysts, the paper focuses on the properties and characterization of amorphous alloy catalysts, and recent developments in the solution-phase synthesis of amorphous alloy nanoparticles. This paper further outlines the applications of amorphous alloys, with special emphasis on the problems and strategies for the application of amorphous alloy nanoparticles in catalytic reactions.

Advances in chemical synthesis and application of metal-metalloid amorphous alloy nanoparticulate catalysts

By altering reaction temperature from –7 to 30 °C, the boron content in Fe–B amorphous powders can be regulated over a wide range, from 23 to 40 atom%; this results from the difference in the apparent activation energies for the deposition of iron and boron atoms.

Amorphous iron–boron powders prepared by chemical reduction of mixed-metal cation solutions: dependence of composition upon reaction temperature

The Morphology and Doping Effects for Ice adhesion on Alumina Surface

Objective: To evaluate the safety and efficacy of transcatheter aortic valve implantation (TAVI) with the novel Prizvalve® system in treating severe aortic stenosis. Methods: This is a single-center, prospective, single-arm, observational study. A total of 11 patients with severe aortic stenosis with high risk or inappropriate for conventional surgical aortic valve replacement (SAVR) were included, and TAVI was achieved with the Prizvalve® system between March 2021 and May 2021 in West China Hospital. Transthoracic echocardiography (TTE) was performed immediately after prosthesis implantation to evaluate mean transaortic gradient and maximal transaortic velocity. The device success rate was calculated, which was defined as (1) the device being delivered via the access, deployed, implanted and withdrawn, (2) mean transaortic gradient<20 mmHg (1 mmHg=0.133 kPa) or a maximal transaortic velocity<3 m/s post TAVI, and without severe aortic regurgitation or paravalvular leak post TAVI. TTE was performed at 30 days after the surgery, and all-cause mortality as well as the major cardiovascular adverse events (including acute myocardial infarction, disabling hemorrhagic or ischemic stroke) up to 30 days post TAVI were analyzed. Results: The age of 11 included patients were (78.1±6.3) years, with 8 males. A total of 10 patients were with NYHA functional class Ⅲ or Ⅳ. Devices were delivered via the access, deployed, implanted and withdrawn successfully in all patients. Post-implant mean transaortic gradient was (7.55±4.08) mmHg and maximal transaortic velocity was (1.78±0.44) m/s, and both decreased significantly as compared to baseline levels (both P<0.05). No severe aortic regurgitation or paravalvular leak was observed post TAVI. Device success was achieved in all the 11 patients. No patient died or experienced major cardiovascular adverse events up to 30 days post TAVI. Mean transaortic gradient was (9.45±5.07) mmHg and maximal transaortic velocity was (2.05±0.42) m/s at 30 days post TAVI, which were similar as the values measured immediately post TAVI (both P>0.05). Conclusions: TAVI with the Prizvalve® system is a feasible and relatively safe procedure for patients with severe aortic stenosis and at high risk or inappropriate for SAVR. Further clinical studies could be launched to obtain more clinical experience with Prizvalve® system.

[Preliminary clinical experience of the novel transcatheter aortic valve system Prizvalve® for the treatment of severe aortic stenosis].

Primary human thyrocytes maintained the function of thyroid hormone production and secretion in vitro

Polysynthetic twinned (PST) TiAl single crystal possesses great potentials for high-temperature applications. The research on high temperature mechanical behavior and wrought process of PST TiAl single crystal have great significance for application in aeroengine blades. In this paper, PST TiAl single crystal was compressed at high temperature to study the dynamic plastic flow behavior. The strength decreased with the increase of temperature and the decrease of strain rate. The processing map of PST TiAl single crystal was calculated using dynamic material model. It is revealed that the wrought temperature of PST TiAl single crystal should be high, whereas the strain rate should be low. The hot deformation activation energy of PST TiAl single crystal was then kinetically calculated to analyse the constitutive equation, which has been verified to be reliable. These paraments and models can guide the selection of hot wrought process and the prediction of high temperature service performance for PST TiAl single crystal, thus providing database to the application of PST TiAl single crystal for designing mechanical systems. 

High temperature plastic flow of polysynthetic twinned TiAl single crystal

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