Cyclic Deformation of Powder Metallurgy Stainless Steel/Mg‐PSZ Composite Materials

In this study, the low‐cycle fatigue (LCF) behavior of powder metallurgy stainless steel/MgO partially stabilized zirconia (Mg‐PSZ) composite materials is presented. The steel matrix based on conventional AISI 304 steel (1.4301) is reinforced with Mg‐PSZ. The investigated composite materials were manufactured using the spark plasma sintering (SPS) technique. Total strain‐controlled LCF tests were performed on materials containing 0, 5, and 10 vol% Mg‐PSZ, respectively, in order to evaluate the influence of the ceramic reinforcement. Electron backscatter diffraction (EBSD) measurements were applied to identify the locations where the martensitic phase transformations in the steel matrix and stress‐assisted as well as athermal martensitic phase transformations of the Mg‐PSZ ceramic reinforcement take place. The resulting cyclic deformation behavior is correlated with the microstructural features of the composite material.     

Metro Maps on Octilinear Grid Graphs

Schematic transit maps (often called “metro maps” in the literature) are important to produce comprehensible visualizations of complex public transit networks. In this work, we investigate the problem of automatically drawing such maps on an octilinear grid with an arbitrary (but optimal) number of edge bends. Our approach can naturally deal with obstacles that should be respected in the final drawing (points of interest, rivers, coastlines) and can prefer grid edges near the real-world course of a line. This allows our drawings to be combined with existing maps, for example as overlays in map services. We formulate an integer linear program which can be used to solve the problem exactly. We also provide a fast approximation algorithm which greedily calculates shortest paths between node candidates on the underlying octilinear grid graph. Previous work used local search techniques to update node positions until a local optimum was found, but without guaranteeing octilinearity. We can thus calculate nearly optimal metro maps in a fraction of a second even for complex networks, enabling the interactive use of our method in map editors.     

Numerical model of optical coherence tomographic vibrography imaging to estimate corneal biomechanical properties

Most techniques measuring corneal biomechanics in vivo are biased by side factors. We demonstrate the ability of optical coherence tomographic (OCT) vibrography to determine corneal material parameters, while reducing current prevalent restrictions of other techniques (such as intraocular pressure (IOP) and thickness dependency). Modal analysis was performed in a finite-element (FE) model to study the oscillation response in isolated thin corneal flaps/eye globes and to analyse the dependency of the frequency response function on: corneal elasticity, viscoelasticity, geometry (thickness and curvature), IOP and density. The model was verified experimentally in flaps from three bovine corneas and in two enucleated porcine eyes using sound excitation (100–110 dB) together with a phase-sensitive OCT to measure the frequency response function (range 50–510 Hz). Simulations showed that corneal vibration in flaps is sensitive to both, geometrical and biomechanical parameters, whereas in whole globes it is primarily sensitive to corneal biomechanical parameters only. Calculations based on the natural frequency shift revealed that flaps of the posterior cornea were 0.8 times less stiff than flaps from the anterior cornea and cross-linked corneas were 1.6 times stiffer than virgin corneas. Sensitivity analysis showed that natural vibration frequencies of whole globes were nearly independent from corneal thickness and IOP within the physiological range. OCT vibrography is a promising non-invasive technique to measure corneal elasticity without biases from corneal thickness and IOP.     

Dynamic instabilities of rod-like eutectic growth patterns: A real-time study

We present a real-time experimental study of the rod-like growth patterns formed during directional solidification in a non-faceted transparent eutectic alloy, succinonitrile–(d)camphor. Slightly convex isotherms were used to slowly increase the pattern spacing λ from an appropriate starting value to the threshold spacing for rod elimination or rod-splitting instabilities allowing a quantitative determination of these thresholds as a function of the solidification rate V. We show that the threshold spacing for rod splitting obeys the general λ ～ V^?1/2 scaling law of eutectic growth, whereas the threshold spacing for rod elimination deviates from this law at low V, exhibiting the same overstability effect as previously reported for lamellar eutectic patterns. We demonstrate that topological defects (walls between hexagon domains) play an important role in rod-splitting processes. We also describe a spatially incoherent mode of oscillation that we observed in disordered rod-like patterns.     

A Biocatalytic Nanomaterial for the Label‐Free Detection of Virus‐Like Particles

The design of nanomaterials that are capable of specific and sensitive biomolecular recognition is an on‐going challenge in the chemical and biochemical sciences. A number of sophisticated artificial systems have been designed to specifically recognize a variety of targets. However, methods based on natural biomolecular detection systems using antibodies are often superior. Besides greater affinity and selectivity, antibodies can be easily coupled to enzymatic systems that act as signal amplifiers, thus permitting impressively low detection limits. The possibility to translate this concept to artificial recognition systems remains limited due to design incompatibilities. Here we describe the synthesis of a synthetic nanomaterial capable of specific biomolecular detection by using an internal biocatalytic colorimetric detection and amplification system. The design of this nanomaterial relies on the ability to accurately grow hybrid protein‐organosilica layers at the surface of silica nanoparticles. The method allows for label‐free detection and quantification of targets at picomolar concentrations.     

Synthetic Polyamine BPA‐C8 Inhibits TGF‐β1‐Mediated Conversion of Human Dermal Fibroblast to Myofibroblasts and Establishment of Galectin‐1‐Rich Extracellular Matrix in Vitro

Cancer‐associated fibroblasts (CAFs) play a role in the progression of malignant tumors. They are formed by conversion of fibroblasts to smooth muscle α‐actin‐positive (SMA‐positive) myofibroblasts. Polyamines are known to change the arrangement of the actin cytoskeleton by binding to the anionic actin. We tested the effect of the synthetic polyamine BPA‐C8 on the transition of human dermal fibroblasts to myofibroblasts induced either by TGF‐β1 alone or by TGF‐β1 together with adhesion/growth‐regulatory galectin‐1. Pre‐existing CAFs, myofibroblasts from pancreatitis, and rat smooth muscle cells were also exposed to BPA‐C8. BPA‐C8 impaired myofibroblast formation from activated fibroblasts, but it had no effect on cells already expressing SMA. BPA‐C8 also reduced the occurrence of an extracellular matrix around the activated fibroblasts. The reported data thus extend current insights into polyamine activity, adding interference with tumor progression to the tumor‐promoting processes warranting study.