Deterministic synthesis of Cu9S5 flakes assisted by single-layer graphene arrays.

The employment of two-dimensional materials, as growth substrates or buffer layers, enables the epitaxial growth of layered materials with different crystalline symmetries with a preferential crystalline orientation and the synthesis of heterostructures with a large lattice constant mismatch. In this work, we employ single crystalline graphene to modify the sulfurization dynamics of copper foil for the deterministic synthesis of large-area Cu9S5 crystals. Molecular dynamics simulations using the Reax force-field are used to mimic the sulfurization process of a series of different atomistic systems specifically built to understand the role of graphene during the sulphur atom attack over the Cu(111) surface. Cu9S5 flakes show a flat morphology with an average lateral size of hundreds of micrometers. Cu9S5 presents a direct band-gap of 2.5 eV evaluated with light absorption and light emission spectroscopies. Electrical characterization shows that the Cu9S5 crystals present high p-type doping with a hole mobility of 2 cm2 V-1 s-1.

Quasi-3D morphology and modulation of focal adhesions of human adult stem cells through combinatorial concave elastomeric surfaces with varied stiffness.

In vivo cell niches are complex architectures that provide a wide range of biochemical and mechanical stimuli to control cell behavior and fate. With the aim to provide in vitro microenvironments mimicking physiological niches, microstructured substrates have been exploited to support cell adhesion and to control cell shape as well as three dimensional morphology. At variance with previous methods, we propose a simple and rapid protein subtractive soft lithographic method to obtain microstructured polydimethylsiloxane substrates for studying stem cell adhesion and growth. The shape of adult renal stem cells and nuclei is found to depend predominantly on micropatterning of elastomeric surfaces and only weakly on the substrate mechanical properties. Differently, focal adhesions in their shape and density but not in their alignment mainly depend on the elastomer stiffness almost regardless of microscale topography. Local surface topography with concave microgeometry enhancing adhesion drives stem cells in a quasi-three dimensional configuration where stiffness might significantly steer mechanosensing as highlighted by focal adhesion properties.

Spatiotemporal characteristics of muscle patterns for ball catching.

What sources of information and what control strategies the central nervous system (CNS) uses to perform movements that require accurate sensorimotor coordination, such as catching a flying ball, is still debated. Here we analyzed the EMG waveforms recorded from 16 shoulder and elbow muscles in six subjects during catching of balls projected frontally from a distance of 6 m and arriving at two different heights and with three different flight times (550, 650, 750 ms). We found that a large fraction of the variation in the muscle patterns was captured by two time-varying muscle synergies, coordinated recruitment of groups of muscles with specific activation waveforms, modulated in amplitude and shifted in time according to the ball's arrival height and flight duration. One synergy was recruited with a short and fixed delay from launch time. Remarkably, a second synergy was recruited at a fixed time before impact, suggesting that it is timed according to an accurate time-to-contact estimation. These results suggest that the control of interceptive movements relies on a combination of reactive and predictive processes through the intermittent recruitment of time-varying muscle synergies. Knowledge of the dynamic effect of gravity and drag on the ball may be then implicitly incorporated in a direct mapping of visual information into a small number of synergy recruitment parameters.

A new ball launching system with controlled flight parameters for catching experiments.

Systematic investigations of sensorimotor control of interceptive actions in naturalistic conditions, such as catching or hitting a ball moving in three-dimensional space, requires precise control of the projectile flight parameters and of the associated visual stimuli. Such control is challenging when air drag cannot be neglected because the mapping of launch parameters into flight parameters cannot be computed analytically. We designed, calibrated, and experimentally validated an actuated launching apparatus that can control the average spatial position and flight duration of a ball at a given distance from a fixed launch location. The apparatus was constructed by mounting a ball launching machine with adjustable delivery speed on an actuated structure capable of changing the spatial orientation of the launch axis while projecting balls through a hole in a screen hiding the apparatus. The calibration procedure relied on tracking the balls with a motion capture system and on approximating the mapping of launch parameters into flight parameters by means of polynomials functions. Polynomials were also used to estimate the variability of the flight parameters. The coefficients of these polynomials were obtained using the launch and flight parameters of 660 launches with 65 different initial conditions. The relative accuracy and precision of the apparatus were larger than 98% for flight times and larger than 96% for ball heights at a distance of 6m from the screen. Such novel apparatus, by reliably and automatically controlling desired ball flight characteristics without neglecting air drag, allows for a systematic investigation of naturalistic interceptive tasks.

Prevention of embolism using calciparine during electrical cardioversion in atrial fibrillation.

On the basis of a review of literature data on cardioversion of AF, a protocol of fast decoagulation using calciparine in non-valvular AF is examined. Pre-cardioversion patients were sedated by administering Diazepam at a personalized dose and without significant subjective disturbances for the patients; this meant not having to involve the anaesthetist.