Biomechanical Gain in Joint Excursion from the Curvature of the Achilles Tendon: Role of the Geometrical Arrangement of Inflection Point, Center of Rotation, and Calcaneus

The dorsal movement of the Achilles tendon during ankle rotation is restricted by anatomical obstructions. Previously, we demonstrated that the anatomical obstruction provides a gain (gainAT) in the proximal displacement of the calcaneus compared to the change in the Achilles tendon length. Here, we empirically validate and extend our previous modeling study by investigating the effects of a broad range of obstruction locations on gainAT. The largest gainAT could be achieved when the obstruction was located on the most ventral and distal sides within the physiological range of the Achilles tendon, irrespective of the ankle position.

Spatial organization of nuclear pores in Xaenopus laevis oocytes

The structure of nuclear pores has been the object of considerable investigation, but how nuclear pores are arranged on the nuclear surface is still less studied. Here, we analyze super-resolution images of the surface of Xenopus laevis oocytes nuclei during development and characterize the arrangement of nuclear pore using tools commonly used to study atomic structural and topological features of ordinary matter. To interpret the experimental results, we perform numerical simulations of octagonal clusters mimicking typical pore shapes and find structures that are in excellence agreement with experiments. The statistical features of the geometrical arrangement does not depend on the type of interaction between the pores, attractive or repulsive, but only on their octagonal geometry. We conclude that the observed arrangement of the pores is mainly is dominated by their octagonal symmetry.

Ring-first Mitral Valve Repair

Mitral valve repair is one of the most frequent interventions in cardiac surgery. It involves eliminating the dysfunctional part(s) of the mitral valve and reconstructing, using the residual tissue or with the addition of prosthetic components, a properly functioning valve, without residual stenosis or regurgitation. A fundamental component of mitral repair is the implantation of a ring (annuloplasty) which reconstitutes the normal, saddle-shaped geometry of the valve. Such ring is usually implanted at the end of the surgical reconstruction regardless of the repair techniques. The implantation of the ring can however change the final anatomy of the valve in an unexpected way and therefore force new corrective surgical actions. We therefore propose a research project that plans the execution of annuloplasty as the first surgical step and then the correction of the valvular disease affecting the leaflets and chordae. The sizing of the ring is always performed on parts of the valve that are usually not changed during the reconstructive surgery, therefore it is possible to decide its size before surgically correcting the valve. In this way we could act on the leaflets and chordae in the definitive geometrical arrangement of the mitral valve.

Geometric Understanding of Local Fluctuation Distribution of Conduction Time in Lined-Up Cardiomyocyte Network in Agarose-Microfabrication Multi-Electrode Measurement Assay

We examined characteristics of the propagation of conduction in width-controlled cardiomyocyte cell networks for understanding the contribution of the geometrical arrangement of cardiomyocytes for their local fluctuation distribution. We tracked a series of extracellular field potentials of linearly lined-up human embryonic stem (ES) cell-derived cardiomyocytes and mouse primary cardiomyocytes with 100 kHz sampling intervals of multi-electrodes signal acquisitions and an agarose microfabrication technology to localize the cardiomyocyte geometries in the lined-up cell networks with 100–300 μm wide agarose microstructures. Conduction time between two neighbor microelectrodes (300 μm) showed Gaussian distribution. However, the distributions maintained their form regardless of its propagation distances up to 1.5 mm, meaning propagation diffusion did not occur. In contrast, when Quinidine was applied, the propagation time distributions were increased as the faster firing regulation simulation predicted. The results indicate the “faster firing regulation” is not sufficient to explain the conservation of the propagation time distribution in cardiomyocyte networks but should be expanded with a kind of community effect of cell networks, such as the lower fluctuation regulation.

Semantic Component Association within Object Classes Based on Convex Polyhedrons

Most objects are composed of semantically distinctive parts that are more or less geometrically distinctive as well. Points on the object relevant for a certain robot operation are usually determined by various physical properties of the object, such as its dimensions or weight distribution, and by the purpose of object parts. A robot operation defined for a particular part of a representative object can be transferred and adapted to other instances of the same object class by detecting the corresponding components. In this paper, a method for semantic association of the object’s components within the object class is proposed. It is suitable for real-time robotic tasks and requires only a few previously annotated representative models. The proposed approach is based on the component association graph and a novel descriptor that describes the geometrical arrangement of the components. The method is experimentally evaluated on a challenging benchmark dataset.

Physical immobilization of particles inspired by pollination

Biomimetic systems often exhibit striking designs well adapted to specific functions that have been inspiring the development of new technologies. Herein, we explored the remarkable ability of honey bees to catch and release large quantities of pollen grains. Hair spacing and height on bees are crucial for their ability to mechanically fix pollen grains. Inspired by this, we proposed the concept of a micropatterned surface for microparticle entrapment, featuring high-aspect-ratio elastic micropillars spaced to mimic the hairy surface of bees. The hypothesis was validated by investigating the ability of polydimethylsiloxane microfabricated patches to fix microparticles. The geometrical arrangement, spacing, height, and flexibility of the fabricated micropillars, and the diameter of the microparticles, were investigated. Higher entrapment capability was found through the match between particle size and pillar spacing, being consistent with the observations that the diameter of pollen grains is similar to the spacing between hairs on bees’ legs. Taller pillars permitted immobilization of higher quantities of particles, consistent with the high aspect ratio of bees’ hairs. Our biomimetic surfaces were explored for their ability to fix solid microparticles for drug-release applications, using tetracycline hydrochloride as a model antibiotic. These surfaces allowed fixation of more than 20 mg/cm2of antibiotic, about five times higher dose than commercialized patches (5.1 mg/cm2). Such bioinspired hairy surfaces could find applications in a variety of fields where dry fixation of high quantities of micrometer-sized objects are needed, including biomedicine, agriculture, biotechnology/chemical industry, and cleaning utensils.

Chemical Routes to Surface Enhanced Infrared Absorption (SEIRA) Substrates

Bottom-up strategies for fabricating SEIRA substrates are presented. For this purpose, wet-chemically prepared gold nanoparticles are coated with a polystyrene shell and subsequently self-assembled into different nanostructures such as quasi-hexagonally ordered gold nanoparticle monolayers, double layers, and honeycomb structures. Furthermore elongated gold nanostructures are obtained by sintering of gold nanoparticle double layers. The optical properties of these different gold nanostructures are directly connected to their morphology and geometrical arrangement – leading to surface plasmon resonances from the visible to the infrared wavelength range. Finally, SEIRA enhancement factors are determined. Gold nanoparticle double layers show the best performance as SEIRA substrates.

Axially perpendicular offset scheme for obtaining Raman spectra of housed samples in glass bottles with minimized glass-peak background

An axially perpendicular offset (APO) scheme based on an axially perpendicular geometrical arrangement of laser illumination and photon detection is proposed as a versatile tool for the minimization of the glass background in direct measurements of Raman spectra of samples housed in glass bottles.