Hydrazine borane (N(2)H(4)BH(3)) is the novel boron- and nitrogen-based material appearing to be a promising candidate in chemical hydrogen storage. It stores 15.4 wt% of hydrogen in hydridic and protic forms, and the challenge is to release H(2) with maximum efficiency, if possible all hydrogen stored in the material. An important step to realize this ambitious goal is to synthesize HB with high yields and high purity, and to characterize it fully. In this work, we report a 2-step synthesis (salt metathesis and solvent extraction-drying) through which N(2)H(4)BH(3) is successfully obtained in 3 days, with a yield of about 80% and a purity of 99.6%. N(2)H(4)BH(3) was characterized by NMR, IR, XRD, TGA and DSC, its stability in dioxane and water was determined, and its thermolysis by-products were characterized. We thus present a complete data sheet that should be very useful for future studies. Furthermore, we propose a discussion on the potential of HB (with H(2) released by either thermolysis or hydrolysis) in chemical hydrogen storage.

This study found that the prevalence of CRT DRI is close to 4.3% at 2.6 years (1.7% per year incidence). Four independent predictive factors of infections were identified including re-intervention, procedure time, dialysis, and primo CRT-ICD implantation. These parameters should be part of the risk-benefit evaluation in patients selected for CRT implantation.

The present Review addresses current developments related to polymer-derived ceramic nanocomposites (PDC-NCs). Different classes of preceramic polymers are briefly introduced and their conversion into ceramic materials with adjustable phase compositions and microstructures is presented. Emphasis is set on discussing the intimate relationship between the chemistry and structural architecture of the precursor and the structural features and properties of the resulting ceramic nanocomposites. Various structural and functional properties of silicon-containing ceramic nanocomposites as well as different preparative strategies to achieve nano-scaled PDC-NC-based ordered structures are highlighted, based on selected ceramic nanocomposite systems. Furthermore, prospective applications of the PDC-NCs such as high-temperature stable materials for thermal protection systems, membranes for hot gas separation purposes, materials for heterogeneous catalysis, nano-confinement materials for hydrogen storage applications as well as anode materials for secondary ion batteries are introduced and discussed in detail.

Long term stability of ceramics at high temperatures is one of the great challenges of the contemporary technology developments. Multi‐component ceramics such as Si–B–C–N systems gain a lot of interest for high temperature applications due to the stability of their amorphous inorganic network arising from strong covalent bonding. The polymer derived ceramics (PDC) route enables the synthesis of such materials from preceramic polymers as well as their manufacturing as specific ceramic geometries, which are difficult to obtain otherwise. This review proposes an overview of the works related to the development of Si–B–C–N ceramics through the PDC route in the last 30 years. A particular focus is made on the relation between the chemical structure of the precursors and the properties of the resulting ceramics. The main topics reviewed are related to the synthesis of tailor‐made polymeric precursors, to their processing to ceramic components, and to the characterization of the material properties and functionalities. The various strategies adopted for the development of shaped Si–B–C–N ceramics as functional materials are presented and the trend of nowadays research for future evolution of Si–B–C–N materials is discussed.

International audienc

A second generation of boron nitride-based porous materials has been synthesized by a double nanocasting process via a carbonaceous template as a medium starting from a zeolite. In the multistep process, we coupled several synthetic strategies such as chemical vapor deposition (CVD) and polymer-derived ceramic (PDCs) routes to prepare carbonaceous templates through infiltration of zeolite Y (FAU structure type) by propylene in the gaseous phase then infiltration of the carbonaceous replica having a high micropore volume (0.67 cm3/g) with polyborazylene in the liquid phase followed by pyrolysis and mold destruction. These porous BN-based architectures present a bimodal pore size distribution with a high portion of micropores (∼0.20 cm3/g) that are unambiguously evidenced by nitrogen physisorption based on a nonporous BN reference isotherm. They exhibited a high specific area (570 m2/g), a high pore volume (0.78 cm3/g), and a lack of long-range ordering as evidenced by BET, XRD and TEM experiments. The two first properties allow to open catalyst applications of these materials.

Using very uniform large-scale chemical vapor deposition grown graphene transferred onto silicon, we were able to identify 15 distinct Raman lines associated with graphene monolayers. This was possible thanks to a combination of different carbon isotopes and different Raman laser energies and extensive averaging without increasing the laser power. This allowed us to obtain a detailed experimental phonon dispersion relation for many points in the Brillouin zone. We further identified a D + D peak corresponding to a double-phonon process involving both an inter-and intravalley phonon.

Background-Cavotricuspid isthmus (CTI) characteristics are rarely documented when comparing catheters in radiofrequency ablation (RFA) of atrial flutter (AFL). Our objectives were (1) to evaluate the impact of CTI morphology and length on ablation procedures and (2) to compare the efficacy of an 8-mm-tip catheter with an irrigated cooled-tip RFA in the subgroup presumed to be more difficult to treat (with a long CTI, Ͼ35 mm). Methods and Results-Over a period of 17 months, 185 patients accepted the protocol and underwent an isthmogram in preparation for RFA. Groups were classified according to CTI length and CTI morphology. RFA was performed with an 8-mm-tip catheter for patients with a short CTI, Յ35 mm (nϭ123), whereas randomization between an 8-mm-tip and a cooled-tip catheter applied to patients with a longer CTI, Ͼ35 mm (nϭ62). For long CTI, 32 patients were assigned to an 8-mm catheter and 30 patients to the cooled-tip RFA ablation group. In this subset, RF application (18.2Ϯ17 versus 19Ϯ13 minutes) and x-ray exposure (20.8Ϯ18 versus 18Ϯ13 minutes) did not differ between the 8-mm-tip and the cooled-tip procedures. Number of applications (9.9Ϯ11 versus 18.6Ϯ15 minutes; PϽ0.0001) and x-ray exposure (11.7Ϯ11 versus 19.5Ϯ16 minutes, Pϭ0.0001) differed significantly between patients with short and long CTIs.Patients with short and straight CTIs required 3 times fewer RFA applications and shorter x-ray exposure compared with other CTI morphologies (pouch-like recesses and concave characteristics). Conclusions-The number of RF applications required for a complete isthmus block in long CTIs is not influenced by the choice between an 8-mm or cooled-tip catheter. Procedure parameters, however, are significantly influenced by CTI length and morphology. Pouch-like recesses and concave characteristics account for much longer ablation times at all