Evaluating the joinability of thin-walled high pressure die cast aluminium for automotive structures using self-piercing rivets

This paper is the first to report successful application of self-pierce riveting (SPR) in thin-walled high pressure die cast (HPDC) aluminium for use in automotive applications. HPDC fabricated AA356x coupons were joined to conventional rolled RC5754 material. A set of industry-relevant joint stacks were created. Priority stacks included cast material as the upper layer. More challenging joints were also fabricated with cast material as the lower layer. Automotive industry key performance indicators were used to assess joint integrity. The key results and recommendations were: • HPDC aluminium was revealed to be able to be joined to rolled aluminium according to vehicle manufacturer automotive standards. • Process boundaries were established for satisfactory SPR joints across a range of material thicknesses and stack types. • SPR joint solutions were proven in the most challenging stacks with cast material as a bottom layer. • Greater variability in the joint key performance indicators was observed in stacks where the cast alloy is the top layer. • Microstructural analysis of both AA356x and RC5754 revealed differences in grain structure and hardness and it is proposed that this accounts for the increased variability. • Strength testing of lap shear joints demonstrated the mechanical effectiveness of an SPR joint including cast material. Under normal vehicle operating conditions, the performance of joints including cast material was equivalent to that of rolled material only joints. Following yielding, joints including cast material suffered a more brittle failure mode leading to differences in performance under crash scenarios

Metabolic and mitochondria alterations induced by SARS-CoV-2 accessory proteins ORF3a, ORF9b, ORF9c and ORF10

Antiviral signaling, immune response and cell metabolism in human body are dysregulated by SARS-CoV-2, the causative agent of the COVID-19. Here, we show that SARS-CoV-2 accessory proteins ORF3a, ORF9b, ORF9c and ORF10 induce a significant mitochondrial and metabolic reprogramming in A549 lung epithelial cells. While all four ORFs caused mitochondrial fragmentation and altered mitochondrial function, only ORF3a and ORF9c induced a marked structural alteration in mitochondrial cristae. ORF9b, ORF9c and ORF10 induced largely overlapping transcriptomes. In contrast, ORF3a induced a distinct transcriptome, including the downregulation of numerous genes for proteins with critical mitochondrial functions and morphology. Genome-Scale Metabolic Models predicted common and private metabolic flux reprogramming, notably a depressed amino acid metabolism, and an enhanced metabolism of specific lipids distinctly induced by ORF3a. These findings reveal metabolic dependencies and vulnerabilities prompted by SARS-CoV-2 accessory proteins that may be exploited to identify new targets for intervention.This research work was funded by the European Commission – NextGenerationEU (Regulation EU 2020/2094), through CSIC's Global Health Platform (PTI+ Salud Global) (COVID-19-117 and SGL2103015), Junta de Andalucía (CV20-20089), Spanish Ministry of Science project (PID2021-123399OB-I00), the Agency for Management of University and Research Grants from Generalitat de Catalunya-AGAUR (2020PANDE00048 and 2021SGR00350) and ICREA foundation (ICREA-Academia-2021 to MC) of Generalitat de Catalunya, and an AESi grant of the Instituto de Salud Carlos III (PI20CIII-00014). TGG is recipient of a Ramón y Cajal contract funded by MCIN/AEU/10.13039/501100011033 and NextGeneration EU/PRTR.N

X-ray photoelectron spectroscopy of ferroelectric semiconductor SbSI crystals

The paper presents the X-ray photoelectron spectra (XPS) of the valence band (VB) and of the principal core levels from the (110) and (001) planes for the ferroelectric semiconductor SbSI single crystal in the temperature range 215-390 K. The excitation source was Al Kα monochromatic radiation (1486.6 eV). XPS were analysed in the energy range 0-1400 eV. Experimentally obtained energies were compared with the results of theoretical ab initio calculations of surface and bulk atoms in the paraelectric and ferroelectric phases. The structure of VB is calculated and confirmed experimentally. Large shifts (3-5 eV) in the core-level binding energies of surface atoms relative to bulk atoms have been observed. They show a dramatic dependence on the surface crystallographic plane. This is the first observation of XPS shifts of that magnitude in solids. Influence of the phase transition on VB and core levels is studied and the mechanism of the XPS shifts in SbSI crystals is discussed