Synthesis of carbon nanothreads from pyridine under variable high-pressure and high-temperature conditions discloses the role of H-bonding in the kinetic control of the reaction.

This paper describes the exohedral N-decoration of multiwalled carbon nanotubes (MWCNTs) with NH-aziridine groups via [2 + 1] cycloaddition of a tert-butyl-oxycarbonyl nitrene followed by controlled thermal decomposition of the cyclization product. The chemical grafting with N-containing groups deeply modifies the properties of the starting MWCNTs, generating new surface microenvironments with specific base (Brønsted) and electronic properties. Both of these features translate into a highly versatile single-phase heterogeneous catalyst (MW@N) with remarkable chemical and electrochemical performance. Its surface base character promotes the Knoevenagel condensation with activity superior to that of related state of the art N-doped and N-decorated carbon nanomaterials; the N-induced electronic surface redistribution drives the generation of high-energy surface "C" sites suitable for O activation and its subsequent electrochemical reduction (ORR).

Thickness dramatically affects the functionality of coatings. Accordingly, the techniques in use to determine the thickness are of utmost importance for coatings research and technology. In this review, we analyse some of the most appropriate methods for determining the thickness of metallic coatings. In doing so, we classify the techniques into two categories: (i) destructive and (ii) non-destructive. We report on the peculiarity and accuracy of each of these methods with a focus on the pros and cons. The manuscript also covers practical issues, such as the complexity of the procedure and the time required to obtain results. While the analysis focuses most on metal coatings, many methods are also applicable to films of other materials.

X-ray fluorescence is often employed in the measurement of the thickness of coatings. Despite its widespread nature, the task is not straightforward because of the complex physics involved, which results in high dependence on matrix effects. Thickness quantification is accomplished using the Fundamental Parameters approach, adjusted with empirical measurements of standards with known composition and thickness. This approach has two major drawbacks: (i) there are no standards for any possible coating and coating architecture and (ii) even relying on standards, the quantification of unknown samples requires the precise knowledge of the matrix nature (e.g., in the case of multilayer coatings the thickness and composition of each underlayer). In this work, we describe a semiquantitative approach to coating thickness measurement based on the construction of calibration curves through simulated XRF spectra built with Monte Carlo simulations. Simulations have been performed with the freeware software XMI-MSIM. We have assessed the accuracy of the methods by comparing the results with those obtained by (i) XRF thickness determination with standards and (ii) FIB-SEM cross-sectioning. Then we evaluated which parameters are critical in this kind of indirect thickness measurement.