Controlling the Cassie-to-Wenzel Transition: an Easy Route towards the Realization of Tridimensional Arrays of Biological Objects

In this paper we provide evidence that the Cassie-to-Wenzel transition, despite its detrimental effects on the wetting properties of superhydrophobic surfaces, can be exploited as an effective micro-fabrication strategy to obtain highly ordered arrays of biological objects. To this purpose we fabricated a patterned surface wetted in the Cassie state, where we deposited a droplet containing genomic DNA. We observed that, when the droplet wets the surface in the Cassie state, an array of DNA filaments pinned on the top edges between pillars is formed. Conversely, when the Cassie-to-Wenzel transition occurs, DNA can be pinned at different height between pillars. These results open the way to the realization of tridimensional arrays of biological objects

Recurrence quantification analysis of heart rate variability to detect both ventilatory thresholds

Aims of this study were: To verify if Recurrence Quantification Analysis (RQA) of Heart Rate Variability (HRV) time series could determine both ventilatory thresholds in individuals with different fitness levels, and to assess the validity of RQA method compared to gasexchange method (GE). The two thresholds were estimated in thirty young individuals during incremental exercise on cycle-ergometer: Heart rate (HR), Oxygen consumption (VO2) and Workload were measured by the two methods (RQA and GE). Repeated measures ANOVA was used to assess main effects of methods and methods-by-groups interaction effects for HR, VO2 and Workload at aerobic (AerT) and anaerobic (AnT) thresholds. Validity of RQA at both thresholds was assessed for HR, VO2 and Workload by Ordinary Least Products (OLP) regression, Typical Percentage Error (TE), Intraclass Correlation Coefficients (ICC) and the Bland Altman plots. No methods-by-groups interaction effects were detected for HR, VO2 and Workload at AerT and AnT. The OLP analysis showed that at both thresholds RQA and GE methods had very strong correlations (r >0.8) in all variables (HR, VO2 and Workload). Slope and intercept values always included the 1 and the 0, respectively. At AerT the TE ranged from 4.02% (5.48 bpm) to 10.47% (8.53 Watts) (HR and Workload, respectively) and in all variables ICC values were excellent (≥0.85). At AnT the TE ranged from 2.53% (3.98 bpm) to 6.64% (7.81 Watts) (HR and Workload, respectively) and in all variables ICC values were excellent (≥0.90). Therefore, RQA of HRV time series is a new valid approach to determine both ventilatory thresholds in individuals with different physical fitness levels, it can be used when gas analysis is not possible or not convenient

Ex vivo effect of vascular wall stromal cells secretome on enteric ganglia

BACKGROUND Mesenchymal stromal cell (MSC)-based therapy is currently under study to treat inflammatory bowel diseases. MSC bioactive products could represent a valid alternative to overcome issues associated with systemic whole-cell therapies. However, MSC anti-inflammatory mechanisms differ between rodents and humans, impairing the reliability of preclinical models. AIM To evaluate the effect of conditioned medium (CM) derived from porcine vascular wall MSCs (pVW-MSCs) on survival and differentiation of porcine and Guinea pig enteric ganglia exposed to lipopolysaccharide (LPS). METHODS Primary cultures of enteric ganglia were obtained by mechanic and enzymatic digestion of ileum resections from Guinea pigs (Cavia porcellus) (GPEG) and pigs (Suus scrofa) (PEG). pVW-MSCs were derived by enzymatic digestion from vascular wall resections of porcine aorta and tested by immunoflowcytometry for MSC immune profile. Enteric ganglia were treated with increasing concentrations of LPS, CM derived by pVW-MSCs or a combination of CM and LPS 1 \u3bcg/mL. Cell count and morphometric analysis of HuD positive neurons and glial fibrillary acidic protein positive glial cells were performed by immunofluorecent staining of cultured ganglia. RESULTS PEG showed a higher number of neurons compared to GPEG. Overall, CM exerted a protective role on LPS-treated enteric ganglia. CM in combination with LPS increased the number of glial cells per ganglion in both cultures evoking glial cells differentiation in porcine cultures. CONCLUSION These findings suggest an immunomodulating activity of pVW-MSCs mediators on the enteric nervous system in inflammatory conditions

Terahertz detection by epitaxial-graphene field-effect-transistors on silicon carbide

We report on room temperature detection of terahertz radiation by means of antenna-coupled field effect transistors (FETs) fabricated using epitaxial graphene grown on silicon carbide. The achieved photoresponsivity (similar to 0.25 V/W) and noise equivalent power (similar to 80 nW/root Hz) result from the combined effect of two independent detection mechanisms: over-damped plasma wave rectification and thermoelectric effects, the latter ascribed to the presence of carrier density junctions along the FET channel. The calculated plasmonic and thermoelectric response reproduces qualitatively well the measured photovoltages; the experimentally observed sign-switch demonstrates the stronger contribution of plasmonic detection compared to the thermoelectric one. These results unveil the potential of plasmonic detectors exploiting epitaxial graphene on silicon carbide for fast large area imaging of macroscopic samples

High performance bilayer-graphene Terahertz detectors

We report bilayer-graphene field effect transistors operating as THz broadband photodetectors based on plasma-waves excitation. By employing wide-gate geometries or buried gate configurations, we achieve a responsivity $\sim 1.2V/W (1.3 mA/W)$ and a noise equivalent power $\sim 2\times 10^{-9} W/Hz^{-1/2}$ in the 0.29-0.38 THz range, in photovoltage and photocurrent mode. The potential of this technology for scalability to higher frequencies and the development of flexible devices makes our approach competitive for a future generation of THz detection systems

Graphene Plasmonic Fractal Metamaterials for Broadband Photodetectors

Metamaterials have recently established a new paradigm for enhanced light absorption in state-of-the-art photodetectors. Here, we demonstrate broadband, highly efficient, polarization-insensitive, and gate-tunable photodetection at room temperature in a novel metadevice based on gold/graphene Sierpinski carpet plasmonic fractals. We observed an unprecedented internal quantum efficiency up to 100% from the near-infrared to the visible range with an upper bound of optical detectivity of 1011 Jones and a gain up to 106, which is a fingerprint of multiple hot carriers photogenerated in graphene. Also, we show a 100-fold enhanced photodetection due to highly focused (up to a record factor of |E/E0| ≈ 20 for graphene) electromagnetic fields induced by electrically tunable multimodal plasmons, spatially localized in self-similar fashion on the metasurface. Our findings give direct insight into the physical processes governing graphene plasmonic fractal metamaterials. The proposed structure represents a promising route for the realization of a broadband, compact, and active platform for future optoelectronic devices including multiband bio/chemical and light sensors