A contamination-free electron-transparent metallic sample preparation method for MEMS experiments with in situ S/TEM

Microelectromechanical systems (MEMS) are currently supporting ground-breaking basic research in materials science and metallurgy as they allow in situ experiments on materials at the nanoscale within electron-microscopes in a wide variety of different conditions such as extreme materials dynamics under ultrafast heating and quenching rates as well as in complex electro-chemical environments. Electron-transparent sample preparation for MEMS e-chips remains a challenge for this technology as the existing methodologies can introduce contaminants, thus disrupting the experiments and the analysis of results. Herein we introduce a methodology for simple and fast electron-transparent sample preparation for MEMS e-chips without significant contamination. The quality of the samples as well as their performance during a MEMS e-chip experiment in situ within an electron-microscope are evaluated during a heat treatment of a crossover AlMgZn(Cu) alloy.Comment: Preprint submitted to Microscopy and Microanalysi

Influence of Fe and Mn on the Microstructure Formation in 5xxx Alloys—Part I: Evolution of Primary and Secondary Phases

The increasing demands for Al sheets with superior mechanical properties and excellent formability require a profound knowledge of the microstructure and texture evolution in the course of their production. The present study gives a comprehensive overview on the primary- and secondary phase formation in AlMg(Mn) alloys with varying Fe and Mn additions, including variations in processing parameters such as solidification conditions, homogenization temperature, and degree of cold rolling. Higher Fe alloying levels increase the primary phase fraction and favor the needle-shaped morphology of the constituent phases. Increasing Mn additions alter both the shape and composition of the primary phase particles, but also promote the formation of dispersoids as secondary phases. The size, morphology, and composition of primary and secondary phases is further affected by the processing parameters. The average dispersoid size increases significantly with higher homogenization temperature and large primary particles tend to fragment during cold rolling. The microstructures of the final soft annealed states reflect the important effects of the primary and secondary phase particles on their evolution. The results presented in this paper regarding the relevant secondary phases provide the basis for an in-depth discussion of the mechanisms underlying the microstructure formation, such as Zener pinning, particle stimulated nucleation, and texture evolution, which is presented in Part II of this study

Microstructural Change during the Interrupted Quenching of the AlZnMg(Cu) Alloy AA7050

This study reports on the effect of interrupted quenching on the microstructure and mechanical properties of plates made of the AlZnMg(Cu) alloy AA7050. Rapid cooling from the solution heat treatment temperature is interrupted at temperatures between 100 and 200 °C and continued with a very slow further cooling to room temperature. The final material’s condition is achieved without or with subsequent artificial ageing. The results show that an improvement in the strength–toughness trade-off can be obtained by using this method. Interrupted quenching at 125 °C with peak artificial ageing leads to a yield strength increase of 27 MPa (538 MPa to 565 MPa) compared to the reference material at the same fracture toughness level. A further special case is the complete omission of an artificial ageing treatment with interrupted quenching at 200 °C. This heat treatment exhibits an 20% increase in fracture toughness (35 to 42 MPa m−1/2) while retaining a sufficient yield strength of 512 MPa for industrial applications. A detailed characterization of the relevant microstructural parameters like present phases, phase distribution and precipitate-free zones is performed using transmission electron microscopy and atom probe tomography

Degradation of Cu nanowires in a low-reactive plasma environment

The quest for miniaturisation of electronic devices is one of the backbones of industry 4.0 and nanomaterials are an envisaged solution capable of addressing these complex technological challenges. When subjected to synthesis and processing, nanomaterials must be able to hold pristine its initial designed properties, but occasionally, this may trigger degradation mechanisms that can impair their application by either destroying their initial morphology or deteriorating of mechanical and electrical properties. Degradation of nanomaterials under processing conditions using plasmas, ion implantation and high temperatures is up to date largely sub-notified in the literature. The degradation of single-crystal Cu nanowires when exposed to a plasma environment with residual active O is herein investigated and reported. It is shown that single-crystal Cu nanowires may degrade even in low-reactive plasma conditions by means of a vapour-solid-solid nucleation and growth mechanism.ISSN:2397-210

The highly GABARAP specific rat monoclonal antibody 8H5 visualizes GABARAP in immunofluorescence imaging at endogenous levels

Abstract The determination of unique functions of GABARAP (gamma-aminobutyric acid type A receptor-associated protein), a member of the highly conserved protein family of mammalian autophagy-related 8 protein (mATG8), within diverse cellular processes remains challenging. Because available anti-GABARAP antibodies perform inadequate, especially within various microscopy-based applications, we aimed to develop an antibody that targets GABARAP but not its close orthologs. Following the latest recommendations for antibody validation including fluorescence protein tagging, genetic and orthogonal strategies, we characterized the resulting anti-GABARAP (8H5) antibody during confocal immunofluorescence imaging in-depth. We compared the antibody staining pattern with that obtained for fluorescence protein tagged GABARAP, GABARAPL1 or GABARAPL2 each ectopically expressed in GABARAP knockout cells. Furthermore, we imaged cells expressing all mATG8 family members at endogenous levels and checked GABARAP knockout cells for unspecific staining under fed or macroautophagy-inducing conditions. Finally, we simultaneously stained cells for endogenous GABARAP and the common autophagosomal marker LC3B. Summarized, the presented antibody shows high specificity for GABARAP without cross-reactivity to other mATG8 family members in immunofluorescence imaging making it a valuable tool for the identification of unique GABARAP functions

Characterization of Zr-Containing Dispersoids in Al–Zn–Mg–Cu Alloys by Small-Angle Scattering

The characterization of Zr-containing dispersoids in aluminum alloys is challenging due to their broad size distribution, low volume fraction, and heterogeneous distribution within the grains. In this work, small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS) were compared to scanning electron microscopy (SEM) and transmission electron microscopy (TEM) regarding their capability to characterize Zr-containing dispersoids in aluminum alloys. It was demonstrated that both scattering techniques are suitable tools to characterize dispersoids in a multi-phase industrial 7xxx series aluminum alloy. While SAXS is more sensitive than SANS due to the high electron density of Zr-containing dispersoids, SANS has the advantage of being able to probe a much larger sample volume. The combination of both scattering techniques allows for the verification that the contribution from dispersoids can be separated from that of other precipitate phases such as the S-phase or GP-zones. The size distributions obtained from SAXS, SANS and TEM showed good agreement. The SEM-derived size distributions were, however, found to significantly deviate from those of the other techniques, which can be explained by considering the resolution-limited restrictions of the different techniques

Sandwich Immunoassay for Soluble Glycoprotein VI in Patients with Symptomatic Coronary Artery Disease

Platelet glycoprotein VI (pGPVI) expression is increased in acute coronary syndrome (ACS), reflecting platelet activation. There is no reliable method available to measure pGPVI. Our aim was to develop a bead-based sandwich immunoassay to measure soluble GPVI (sGPVI). METHODS: Based on antibodies for sGPVI developed earlier, we established and validated a bead-based sandwich immunoassay in 2438 consecutive patients with stable angina pectoris (SAP; n = 1371), non-ST-elevation myocardial infarction (NSTEMI; n = 724), and ST-elevation MI (STEMI; n = 343). In a subgroup (n = 1011), we measured surface expression of pGPVI using flow cytometry. RESULTS: The assay revealed a working range of 8-500 ng/L. Intra- and interassay imprecision was <7% and <14%, respectively. Patients with NSTEMI and STEMI showed significantly lower mean sGPVI concentrations than patients with SAP [mean (SD), 8.4 (3.6) μg/L and 8.6 (4.1) μg/L vs 9.8 (4.8) μg/L; P = 0.002], whereas subgroup analysis revealed significantly enhanced pGPVI in NSTEMI (n = 276) and STEMI (n = 80) patients compared with SAP (n = 655) [mean fluorescence intensity (SD), 21.2 (8.1) and 19.8 (6.8) vs 18.5 (7.7); P = 0.002 and P = 0.018]. pGPVI and sGPVI were inversely correlated (r = -0.076; P = 0.023). Area under the ROC curve was 0.716, 95% CI 0.681-0.751, for sGPVI, distinguishing patients with SAP from those with ACS, and was superior (P = 0.044) to the curve of subgroup analysis for pGPVI (0.624, 95% CI 0.586-0.662). sGPVI (P = 0.023) and pGPVI (P = 0.028) had better association with the development of ACS than troponin I (P = 0.055) in the very early stage of disease, based on logistic regression analysis. CONCLUSIONS: This sandwich immunoassay reliably measures sGPVI and may help to identify patients with ACS earlier than other laboratory markers

Genome-wide, large-scale production of mutant mice by ENU mutagenesis.

In the post-genome era, the mouse will have a major role as a model system for functional genome analysis. This requires a large number of mutants similar to the collections available from other model organisms such as Drosophila melanogaster and Caenorhabditis elegans. Here we report on a systematic, genome-wide, mutagenesis screen in mice. As part of the German Human Genome Project, we have undertaken a large-scale ENU-mutagenesis screen for dominant mutations and a limited screen for recessive mutations. In screening over 14,000 mice for a large number of clinically relevant parameters, we recovered 182 mouse mutants for a variety of phenotypes. In addition, 247 variant mouse mutants are currently in genetic confirmation testing and will result in additional new mutant lines. This mutagenesis screen, along with the screen described in the accompanying paper, leads to a significant increase in the number of mouse models available to the scientific community. Our mutant lines are freely accessible to non-commercial users (for information, see http://www.gsf.de/ieg/groups/enu-mouse.html)