Decision support in early development phases—A case study from machine engineering

In the case study presented in this paper we consider early development phases of a mechanical product. We want to evaluate different concepts and decide which one(s) to pursue. A problem in early phases is that usually no test runs are available. In our case study, based on a standard, there are ways to compute the lifetime distributions of the components of the different concepts. Some parameters needed for these computations are not known precisely. Unfortunately, the lifetime distributions of the components are highly sensitive to these parameters. Our approach is to equip these parameters with distributions. These distributions would be called prior distributions in Bayesian terminology, but no update is possible since no test runs are available. Our approach implies that the distribution of the system lifetime for each concept is random, i.e. we get random elements in the space of lifetime distributions. Using Monte-Carlo simulations, we demonstrate several ways to compare the random lifetime distributions of the concepts. Some of these comparisons use stochastic orderings. We also introduce a new stochastic ordering which is particularly suitable for reliability purposes. Our case study, consisting of three scenarios, allows us to demonstrate some conclusions that can be reached.     

Anisotropic Crystalline Protein Nanolayers as Multi‐Functional Biointerface for Patterned Co‐Cultures of Adherent and Non‐Adherent Cells in Microfluidic Devices

The spatial arrangement of cells in their microenvironment is known to significantly influence cellular behavior, thus making the control of cellular organization an important parameter of in vitro co‐culture models. However, recent advances in micropatterning co‐culture methods within biochips do not address the simultaneous cultivation of anchorage‐dependent and non‐adherent cells. To address this methodological gap we combine S‐layer technology with microfluidics to pattern co‐cultures to study the cell‐to‐cell and cell‐to‐surface interactions under physiologically relevant conditions. We exploit the unique self‐assembly properties of SbpA and SbsB S‐layers to create an anisotropic protein nanobiointerface on‐chip with spatially‐defined cytophilic (adhesive) and cytophobic (repulsive) properties. While microfluidics control physical parameters such as shear force and flow velocities, our anisotropic protein nanobiointerface regulates the biological aspects of the co‐culture method including biocompatibility, biostability, and affinity to non‐adherent cells. The reliability and reproducibility of our microfluidic co‐culture strategy based on laminar flow patterned protein nanolayers is envisioned to advance in vitro models for biomedical research.     

Untersuchungen zum Kristallabbau bei der Reduktion von Wüstit

Reduktionsversuche an auf Eisen aufoxydiertem Wüstit mit Kohlenmonoxid-Kohlendioxid-Stickstoff- und Wasserstoff-Wasserdampf-Stickstoff-Gasgemischen. Mikroskopische Beobachtung der anreduzierten Wüstitoberfläche. Beeinflussung der Reduktion durch die Oberflächentopographie des Wüstits. Analogie der Wüstitreduktion unter gleichgewichtsnahen Bedingungen zur Kristallverdampfung.     

Zweiphasige Mischungen aus Polyamid 6 und Polyäthylen

Polymer blends of polyamide 6 and polyethylene are obtained by application of high shearing forces to the two component polymer melt. No formation of block and of graft copolymers occurs. The polymer blend consists of two separate and mutually incompatible phases of both components, determining its bulk properties. To improve the compatibility of both polymers, experiments were performed to graft polyamide 6 onto polyethylene. It could be shown that polyethylene modified with maleic anhydride was especially suited for this purpose. Polyamide 6 chains could be grafted onto this modified polyethylene by anionic polymerization. The mechanical properties of a mixture of the graft copolymer with polyamide 6 are significantly better than those of a mere polyamide-6-polyethylene blend. This improvement is attributed to a greater homogenity of the two phase mixture if the graft copolymer is added.     

17-4PH不锈钢纳米析出物的磁小角中子散射研究

本文充分发挥中子对磁灵敏、穿透力强等技术优势,利用加载磁场小角中子散射实验技术研究核电站实际服役14年的阀杆17 4PH不锈钢样品。结果表明,与不加磁场时相比,加载磁场条件下二维散射图谱呈明显各向异性,在散射矢量垂直于磁场方向上散射强度显著增强。利用多分散球模型对数据进行拟合,结合原子探针实验结果分析得出,衬度的增加降低了Cu析出物周围元素分布不均匀对散射的相对贡献,从而有助于更加准确地获得Cu纳米析出物的尺寸。     

On the non-destructive detection of fatigue damage in industrial aluminium alloys by positron annihilation

The average positron lifetime has been determined non-destructively and in-situ during fully symmetric push-pull fatigue experiments in the bulk material of the aluminium alloys 2024 T3 and 7075 T6 using a servo-hydraulic fatigue testing system equipped with a mobile positron beam produced by a ⁷²Se/⁷²As generator (initial activity of ≈ 0.9 MBq; average positron penetration depth ≥1 mm). Contrary to earlier investigations on stainless steel using the same experimental approach, no variation of the average positron lifetime could be observed during fatigue and neither early nor late stages of fatigue damage could be revealed. It is concluded that fatigue induced changes of the defect spectra in technologically relevant aluminium alloys are masked for the present method by saturation trapping in precipitates. A sufficiently high increase of the dislocation density and the creation of vacancy clusters must be confined to the vicinity of propagating fatigue cracks or the fatal fatigue crack. Therefore the zone with sufficient detectable fatigue damage has not enough statistical weight to modify the average positron lifetime of the aluminium alloy bulk material.