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Eingeladener Vortrag
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A Round Robin study has been carried out to estimate the impact of the human element in small-angle scattering data analysis. Four corrected datasets were provided to participants ready for analysis. All datasets were measured on samples containing spherical scatterers, with two datasets in dilute dispersions, and two from powders.
Most of the 46 participants correctly identified the number of populations in the dilute dispersions, with half of the population mean entries within 1.5 % and half of the population width entries within 40 %, respectively. Due to the added complexity of the structure factor, much fewer people submitted answers on the powder datasets.
For those that did, half of the entries for the means and widths were within 44 % and 86 % respectively. This Round Robin experiment highlights several causes for the discrepancies, for which solutions are proposed.
Introduction
(2020)
The purpose of this book is to provide a comprehensive collection of analytical methods that are commonly used to measure nanoparticles, providing information on one, or more, property of importance. The chapters provide up-to-date information and guidance on the use of these techniques, detailing the manner in which they may be reliably employed. Within this chapter, we detail the rationale and context of the whole book, which is driven by the observation of a low level of reproducibility in nanoparticle research. The aim of the book is to encourage awareness of both the strengths and weaknesses of the various methods used to measure nanoparticles and raise awareness of the range of methods that are available. The editors of the book have, for many years, been engaged in European projects and standardization activities concerned with nanoparticle analysis and have identified authors who are experts in the various methods included within the book. This has produced a book that can be used as a definitive guide to current best practice in nanoparticle measurement.
New reference material candidates for traceable size measurement of nonspherical nanoparticles
(2019)
Size measurement of nanoparticles (NP) becomes a challenging analytical problem when non-spherical shapes must be traceably measured. However, most industrial NPs have irregular shapes and broad size distribution making it often more complex to follow European regulatory to identify a material as a nanomaterial according to which accurate measurement of the smallest dimension and its size Distribution is necessary.
The European research project nPSize - Improved traceability chain of nanoparticle size measurements aims to fill this gap by developing potential non-spherical reference nanoparticles, measurement procedures and physical modelling to improve the traceability chain, comparability and compatibility for NP size measurements between different methods. Therefore, new model NP with well-controlled shape has been synthesized and are supposed to be systematically characterized using the traceable methods scanning/transmission electron microscopy, atomic force microscopy and small angle X-ray scattering.
Following NP candidates are under investigation with respect to their homogeneity and stability: (i) titania nanoplatelets (10-15 nm thickness x 50-100 nm lateral), (ii) titania bipyramides (~60 nm length x 40 nm width), (iii) titania acicular particles (100 nm length x 15-20 nm width; aspect ratio 5.5/6), (iv) gold nanorods (~10 nm width x 30 nm length), and (v) gold nanocubes (~55 nm x 55 nm x 55 nm). In addition, sample preparation procedures as well as measurement analysis procedures with evaluation of appropriate measurands and descriptors for each material class and method are being developed to support standardization. To underpin the traceability of the size measurement of nonspherical NP, physical modelling of the signals in e.g. electron microscopy techniques will be used and in combination, the implementation of machine learning is aimed to facilitate measurement Analysis procedures, especially regarding the accurate thresholding/segmentation of the NPs.
Disc brakes are widely used in cars, trains, and other vehicles. For understanding the basic processes occurring during the friction process, information on the surface topography of brake pads and discs is needed, in addition to information about chemistry and thermodynamics. In this paper, samples of pads and discs were analysed using white light interferometry. The topography of the surfaces was measured quantitatively. Using software tools described in a previous paper [Wear 248 (2001) 121], the distributions of area, height, and slope of the contact patches were computed. Characteristic properties of the contact patches were found to describe the influence of the test parameters such as friction power and testing time.