Influence of Interstitial Oxygen on the Tribology of Ti6Al4V

Titanium alloys are used for their good mechanical and corrosion properties, but generally experience poor wear behavior. This can effectively be counteracted by a thermal oxidation treatment, reducing wear significantly. Employing a special sample preparation, we study the transition of tribological properties between thermally oxidized and bulk Ti6Al4V on a single sample. While oxygen signal intensity and hardness followed an exponential decay from the surface to bulk material, tribological results showed a step-like transition from low to high friction and wear with increasing distance from the surface. Low wear was associated with minor abrasive marks, whereas high wear showed as severe adhesive material transfer onto the steel counter body. Besides the mechanical property of hardness, also a change in fracture behavior by interstitial oxygen could influence the observed tribological behavior

Unusual Armadillo Fold in the Human General Vesicular Transport Factor p115

The golgin family gives identity and structure to the Golgi apparatus and is part of a complex protein network at the Golgi membrane. The golgin p115 is targeted by the GTPase Rab1a, contains a large globular head region and a long region of coiled-coil which forms an extended rod-like structure. p115 serves as vesicle tethering factor and plays an important role at different steps of vesicular transport. Here we present the 2.2 Å-resolution X-ray structure of the globular head region of p115. The structure exhibits an armadillo fold that is decorated by elongated loops and carries a C-terminal non-canonical repeat. This terminal repeat folds into the armadillo superhelical groove and allows homodimeric association with important implications for p115 mediated multiple protein interactions and tethering

Vectors for co-expression of an unrestricted number of proteins

A vector system is presented that allows generation of E. coli co-expression clones by a standardized, robust cloning procedure. The number of co-expressed proteins is not limited. Five ‘pQLink’ vectors for expression of His-tag and GST-tag fusion proteins as well as untagged proteins and for cloning by restriction enzymes or Gateway cloning were generated. The vectors allow proteins to be expressed individually; to achieve co-expression, two pQLink plasmids are combined by ligation-independent cloning. pQLink co-expression plasmids can accept an unrestricted number of genes. As an example, the co-expression of a heterotetrameric human transport protein particle (TRAPP) complex from a single plasmid, its isolation and analysis of its stoichiometry are shown. pQLink clones can be used directly for pull-down experiments if the proteins are expressed with different tags. We demonstrate pull-down experiments of human valosin-containing protein (VCP) with fragments of the autocrine motility factor receptor (AMFR). The cloning method avoids PCR or gel isolation of restriction fragments, and a single resistance marker and origin of replication are used, allowing over-expression of rare tRNAs from a second plasmid. It is expected that applications are not restricted to bacteria, but could include co-expression in other hosts such as Bacluovirus/insect cells

Physical signatures of discontinuities of the time-dependent exchange-correlation potential

The exact exchange-correlation (XC) potential in time-dependent density-functional theory (TDDFT) is known to develop steps and discontinuities upon change of the particle number in spatially confined regions or isolated subsystems. We demonstrate that the self-interaction corrected adiabatic local-density approximation for the XC potential has this property, using the example of electron loss of a model quantum well system. We then study the influence of the XC potential discontinuity in a real-time simulation of a dissociation process of an asymmetric double quantum well system, and show that it dramatically affects the population of the resulting isolated single quantum wells. This indicates the importance of a proper account of the discontinuities in TDDFT descriptions of ionization, dissociation or charge transfer processes.Comment: 17 pages, 6 figure

Plyometrics can preserve peak power during 2 months of physical inactivity: an RCT including a one-year follow-up

Objective: Inactivity results in a marked loss of muscle function, especially in movements requiring high power, force, and rate of force development. The aim of the present study was to evaluate if jump training can prevent these deteriorating effects of physical inactivity. Methods: Performance and muscle activity during several types of jumps was assessed directly before and after 60 days of bed rest as well as during follow-up visits in 23 male participants. Participants in the jump training group (JUMP, 12 participants) trained 5-6x per week during the bed rest period in a sledge jump system that allows jumps in a horizontal position, whereas the control group (CTRL, 11 participants) did not train. Results: Performance and muscle activity considerably decreased after bed rest in the control group but not in the training group, neither for countermovement jumps (peak power CTRL -31%, JUMP +0%, group × time interaction effect p < 0.001), nor for squat jumps (peak power CTRL -35%, JUMP +1%, p < 0.001) and repetitive hops (peak force CTRL -35%, JUMP -2%, p < 0.001; rate of force development CTRL -53%, JUMP +4%, p < 0.001). The control group\u27s performance had returned to baseline 3 months after bed rest. Conclusion: Despite the short exercise duration, the jump training successfully prevented power and strength losses throughout 2 months of bed rest.Thus, plyometrics can be recommended as an effective and efficient type of exercise for sedentary populations, preventing the deterioration of neuromuscular performance during physical inactivity

Generating FAIR research data in experimental tribology

Solutions for the generation of FAIR (Findable, Accessible, Interoperable, and Reusable) data and metadata in experimental tribology are currently lacking. Nonetheless, FAIR data production is a promising path for implementing scalable data science techniques in tribology, which can lead to a deeper understanding of the phenomena that govern friction and wear. Missing community-wide data standards, and the reliance on custom workflows and equipment are some of the main challenges when it comes to adopting FAIR data practices. This paper, first, outlines a sample framework for scalable generation of FAIR data, and second, delivers a showcase FAIR data package for a pin-on-disk tribological experiment. The resulting curated data, consisting of 2,008 key-value pairs and 1,696 logical axioms, is the result of (1) the close collaboration with developers of a virtual research environment, (2) crowd-sourced controlled vocabulary, (3) ontology building, and (4) numerous – seemingly – small-scale digital tools. Thereby, this paper demonstrates a collection of scalable non-intrusive techniques that extend the life, reliability, and reusability of experimental tribological data beyond typical publication practices