Dokument-ID Dokumenttyp Autoren/innen Persönliche Herausgeber/innen Haupttitel Abstract Auflage Verlagsort Verlag Herausgeber (Institution) Erscheinungsjahr Titel des übergeordneten Werkes Jahrgang/Band ISBN Veranstaltung Veranstaltungsort Beginndatum der Veranstaltung Enddatum der Veranstaltung Ausgabe/Heft Erste Seite Letzte Seite URN DOI Lizenz Datum der Freischaltung OPUS4-53884 Zeitschriftenartikel Pellegrino, Francesco; Ortel, Erik; Mielke, Johannes; Schmidt, R.; Maurino, V.; Hodoroaba, Vasile-Dan Customizing New Titanium Dioxide Nanoparticles with Controlled Particle Size and Shape Distribution: A Feasibility Study Toward Reference Materials for Quality Assurance of Nonspherical Nanoparticle Characterization An overview is given on the synthesis of TiO2 nanoparticles with well-defined nonspherical shapes (platelet like, bipyramidal, and elongated), with the focus on controlled, reproducible synthesis, as a key requirement for the production of reference materials with homogeneous and stable properties. Particularly with regard to the nanoparticle shapes, there is a high need of certified materials, solely one material of this type being commercially available since a few months (elongated TiO2). Further, measurement approaches with electron microscopy as the golden method to tackle the nanoparticle shape are developed to determine accurately the size and shape distribution for such nonspherical particles. A prerequisite for accurate and easy (i.e., automated) image analysis is the sample preparation, which ideally must ensure a deposition of the nanoparticles from liquid suspension onto a substrate such that the particles do not overlap, are solvent-free, and have a high deposition density. Challenges in the Synthesis of perfectly monodispersed and solvent-free TiO2 nanoparticles of platelet and acicular shapes are highlighted as well as successful measurement approaches on how to extract from 2D projection electron micrographs the most accurate spatial information, that is, true 3D size, for example, of the bipyramidal nanoparticles with different geometrical orientations on a substrate. Wiley-VCH 2021 Advanced Engineering Materials 24 6 1 10 urn:nbn:de:kobv:b43-538849 10.1002/adem.202101347 https://creativecommons.org/licenses/by/4.0/deed.de 2021-12-02 OPUS4-36792 Zeitschriftenartikel Babick, F.; Mielke, Johannes; Wohlleben, W.; Weigel, St.; Hodoroaba, Vasile-Dan How reliably can a material be classified as a nanomaterial? Available particle-sizing techniques at work Currently established and projected regulatory frameworks require the classification of materials (whether nano or non-nano) as specified by respective definitions, most of which are based on the size of the constituent particles. This brings up the question if currently available techniques for particle size determination are capable of reliably classifying materials that potentially fall under these definitions. In this study, a wide variety of characterisation techniques, including counting, fractionating, and spectroscopic techniques, has been applied to the same set of materials under harmonised conditions. The selected materials comprised well-defined Quality control materials (spherical, monodisperse) as well as industrial materials of complex shapes and considerable polydispersity. As a result, each technique could be evaluated with respect to the determination of the number-weighted median size. Recommendations on the most appropriate and efficient use of techniques for different types of material are given. Springer 2016 Journal of Nanoparticle Research 18 6 Article 158, 1 40 urn:nbn:de:kobv:b43-367922 10.1007/s11051-016-3461-7 http://creativecommons.org/licenses/by/3.0/de/deed.de 2016-07-07 OPUS4-38436 Zeitschriftenartikel Mielke, Johannes; Dohányosová, P.; Lopez, S.; Hodoroaba, Vasile-Dan Electrospray deposition of nanoparticles on TEM grids The authors have tested the prototype of an electrospray deposition system developed by the company RAMEM under its trademark IONER. To test the prototype and assess its performance, several materials have been sprayed onto TEM grids and the resulting particle distributions were compared to more traditional sample preparation strategies like the "drop on grid" method. Operation parameters such as the sample flow-rate, capillary - substrate distance, electric field strength and sampling period length have been optimized. It was found that the particles deposited by electrospray generally show a much more homogeneous spatial distribution on the substrate and a substantial increase of the number of single particles, which are much better suited to an automatic image evaluation procedure than the agglomerated particles observed otherwise. The applicability of the technique to a broad range of materials is demonstrated by various examples, but also the influence of the substrate, the choice of the particular TEM grid, on the obtained spatial particle distribution is assessed. Cambridge 2016 Microscopy and Microanalysis 22 Suppl 3 1846 1847 10.1017/S1431927616010072 2016-11-24 OPUS4-38445 Zeitschriftenartikel Mielke, Johannes; Babick, F.; Uusimäki, T.; Müller, P.; Verleysen, E.; Hodoroaba, Vasile-Dan Evaluation of electron microscopy techniques for the purpose of classification of nanomaterials Electron microscopy techniques such as TEM, STEM, SEM or TSEM (transmission in SEM) are capable of assessing the size of individual nanoparticles accurately. Nevertheless, the challenging aspect is sample preparation from powder or liquid form on the substrate, so that a homogeneous distribution of well-separated (deagglomerated) particles is attained. The systematic study in this work shows examples where the extraction of the critical, smallest particle dimension - as the decisive particle parameter for the classification as a NM - is possible by analysing the sample after ist simple, dry preparation. The consequences of additional typical issues like loss of information due to screening of smaller particles by larger ones or the (in)ability to access the constituent particles in aggregates are discussed. Cambridge 2016 Microscopy and Microanalysis 22 Suppl. 3 936 937 10.1017/S1431927616005523 2016-11-25 OPUS4-34922 Zeitschriftenartikel Müller, P.; Mielke, Johannes; Hodoroaba, Vasile-Dan; Kägi, R.; Ryner, M. Assessment of different electron microscopy techniques for particle size quantification of potential nanomaterials While nano-scaled intermediate and consumer products are omnipresent in many industries, one challenge consists in the development of methods that reliably identify, characterize and quantify nanomaterials both as a substance and in various matrices. For product registration purposes, the European Commission proposed a definition for nanomaterial which requires a quantitative size determination of the primary particles in a sample down to sizes of 1 nm. According to a material is defined as nano if 50% of the primary particles are observed to comprise a smallest dimension <100 nm. The NanoDefine project was set up to develop and validate a robust, readily implementable and cost-effective measurement approach to obtain a quantitative particle size distribution and to distinguish between nano and non-nano materials according to the definition Among the available particle sizing techniques, electron microscopy was found to be one option meeting most of the requirements of the regulation. However, the use of electron microscopy for particle sizing is often limited by cost per sample, availability in industry, particle agglomeration/aggregation, extremely broad size distributions, 2D materials and operator bias in case of manual evaluation. New York, NY Cambridge University Press Microscopy Society of America 2015 Microscopy and microanalysis 21 Suppl. 3 Paper 1200, 2403 2404 10.1017/S1431927615012799 2016-02-20 OPUS4-34923 Zeitschriftenartikel Mielke, Johannes; Rades, Steffi; Ortel, Erik; Salge, T.; Hodoroaba, Vasile-Dan Improved spatial resolution of EDX/SEM for the elemental analysis of nanoparticles The interest in nanoparticles remains at a high level in fundamental research since many years and increasingly, nanoparticles are incorporated into consumer products to enhance their performance. Consequently, the accurate and rapid characterization of nanoparticles is more and more demanded. Electron microscopy (SEM, TSEM and TEM) is one of the few techniques which are able to image individual nanoparticles. It was demonstrated recently that the transmission electron microscopy at a SEM can successfully be applied as a standard method to characterize accurately the size (distribution) and shape of nanoparticles down to less than 10 nm. New York, NY Cambridge University Press Microscopy Society of America 2015 Microscopy and microanalysis 21 Suppl. 3 Paper 0855, 1713 1714 10.1017/S1431927615009344 2016-02-20 OPUS4-33258 Beitrag zu einem Tagungsband Hodoroaba, Vasile-Dan; Rades, Steffi; Salge, T.; Mielke, Johannes; Ortel, Erik; Schmidt, R. Characterisation of nanoparticles by means of high-resolution SEM/EDS Advances in scanning electron microscopy (SEM) enable the high-resolution imaging of single nanoparticles (NPs) with sizes well below 10 nm. The SEM analysis in transmission mode (T-SEM) of NPs on thin film supports has many benefits when compared to the analysis of NPs on bulk substrates. The enhanced material (mass - thickness) contrast of the T-SEM imaging mode is well suited for in-depth and, particularly valuable, to very accurate, traceable, lateral dimensional measurements of NPs. Compared to samples prepared on bulk substrates, T-SEM with energy dispersive X-ray spectroscopy (EDS) achieves a drastically improved spatial resolution of the emitted X-rays. The poor signal-to-noise ratio of the X-ray spectra emitted by a single nanoparticle (NP) can be improved by the use of high-sensitivity (high collection solid angle) silicon drift (SDD), energy-dispersive X-ray spectrometers (EDS). The EDS spectral imaging of a single NP with a spatial resolution below 10 nm has become possible. This is demonstrated by means of various examples of nanostructures. Advanced data processing of T-SEM/EDS results sets the stage for the automated classification of NPs by feature analysis. This method combines the detection of morphological structures of interest by image processing of T-SEM micrographs with the chemical classification by EDS. European microbeam analysis society (EMAS) 2015 EMAS 2015 - 14th European workshop on modern developments and applications in microbeam analysis 978-90-8227-691-6 EMAS 2015 - 14th European workshop on modern developments and applications in microbeam analysis Portoroz, Slovenia 03.05.2015 07.05.2015 NUR code:972 - Materials Science, 187-199 10.1088/1757-899X/109/1/012006 2016-02-20 OPUS4-38947 Forschungsbericht Hodoroaba, Vasile-Dan; Mielke, Johannes Techniques evaluation report for selection of characterisation methods This report is the result of a comprehensive study on the available CMs which come potentially in question for the reliable analysis of the number based size distribution of a nanomaterial according to the EC recommendation for a definition of nanomaterial. Based on the performance criteria already established in NanoDefine the potential CMs are evaluated according to studies available in the literature as well as following the expertise of the NanoDefine consortium partners. The specific advantages and disadvantages of each method with respect to its applicability to the scope of NanoDefine are particularly highlighted. An CM evaluation table is produced so that the mostly suited CMs with respect to the EC definition can be grouped and recommended to the corresponding NanoDefine work packages for further specific development (improvement and adaption), or for direct validation and standardisation, respectively. The actual evaluation report including the recommended CMs will be revised and, if necessary, eventually updated at the mid time of the project. The update will be jointly discussed in the NanoDefine consortium on the basis of the results of testing the methods on the NanoDefine real world materials. Wageningen, The Netherlands The NanoDefine Consortium 2015 D3.1, 1 57 urn:nbn:de:kobv:b43-389473 http://www.gesetze-im-internet.de/urhg/index.html 2017-01-13 OPUS4-38982 Forschungsbericht Hodoroaba, Vasile-Dan; Mielke, Johannes Templates for nanomaterial characterisation of tier 1 and tier 2 measurement methods The EU FP7 NanoDefine project was launched in November 2013 and will run until October 2017. The Project is dedicated to support the implementation of the EU Recommendation on the Definition of Nanomaterial by the provision of the required analytical tools and respective guidance. Main goal is to develop a novel tiered approach consisting of (i) rapid and cost-efficient screening methods and (ii) confirmatory measurement methods. The "NanoDefiner" eTool will guide potential end-users, such as concerned industries and regulatory bodies as well as enforcement and contract laboratories, to reliably classify if a material is nano or not. To achieve this objective, a comprehensive inter-laboratory evaluation of the performance of current characterisation techniques, instruments and software is performed. Instruments, software and methods are further developed. Their capacity to reliably measure the size of particulates in the size range 1-100 nm and above (according to the EU definition) is validated. Technical reports on project results are published to reach out to relevant stakeholders, such as policy makers, regulators, industries and the wider scientific community, to present and discuss our goals and results, to ensure a continuous exchange of views, needs and experiences obtained from different fields of expertise and application, and to finally integrate the resulting feedback into our ongoing work on the size-related classification of nanomaterials. Wageningen, The Netherlands The NanoDefine Consortium The NanoDefine Consortium 2014 1 74 urn:nbn:de:kobv:b43-389827 http://www.gesetze-im-internet.de/urhg/index.html 2017-01-18 OPUS4-38964 Forschungsbericht Babick, F.; Mielke, Johannes; Hodoroaba, Vasile-Dan; Weigel, St.; Wohlleben, W. Critical review manuscript with real-world performance data for counting, ensemble and separating methods including in-build mathematical conversion to number distributions submitted for publication The content of the paper is the assessment of the performance of (conventional) measurement techniques (MTs)with respect to the classification of disperse materials according to the EC recommendation for a definition of nanomaterial. This performance essentially refers to the accurate assessment of the number weighted median of (the constituent) particles. All data and conclusions are based on the analytical study conducted as real-world performance testing. It comprised different types of MTs (imaging, counting, fractionating, spectroscopic and integral) as well as different types of materials. Beside reference materials with well-defined size distribution the study also included several commercial powders (variation of particle composition, morphology, coating, size range and polydispersity). In order to ensure comparability of measurement results, the participants were guided to use uniform protocols in sample preparation, conducting measurements, data analysis and in reporting results. Corresponding documents have been made public, in order to support the reviewing process of the paper, respectively to ensure the reproducibility of data by other users under the same conditions. The scientific paper relies on a comprehensive set of revised measurement data reported in uniform templates, completely describes the experimental procedures and discusses the MTs' performance for selected materials in detail. Even more, the study is summarised and evaluated, which leads to recommendations for the use of MTs within a tiered approach of NM characterisation. In addition, the paper critically examines the factors that may affect the outcome of such a comparison among different MTs. Wageningen, The Netherlands The NanoDefine Consortium 2016 D3.3, 1 72 urn:nbn:de:kobv:b43-389646 http://www.gesetze-im-internet.de/urhg/index.html 2017-01-13