Recently carbon nanostructured materials are more attractive for the supercapacitor applications. Pure carbon nanotubes (CNTs) and double walled nitrogen doped carbon nanotubes (N-DWCNTs) have been synthesized for electrode material for the Supercapacitor applications. The N-DWCNTs were synthesized by Thermal Chemical Vapor Depositions (T-CVD) and they are coil shaped. The synthesized N-DWCNTs were characterized by powder X-ray diffraction (XRD) technique. The morphology of coil shaped N-DWCNTs were revealed by the Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The Electrochemical performance of pure CNTs and N-DWCNTs was analyzed using Cyclic Voltammetry (CV) with 0.5 M H2SO4 electrolyte. It showed the good pseudocapacitance behavior for N-DWCNTs. Electrochemical impedance spectroscopy (EIS) was measured for N-DWCNTs and showed the smaller charge transfer resistance (Rct – 7.731 Ω) which is much smaller than that of CNTs (23.69 Ω). The specific capacitance was measured for pure CNTs (23.40 F/g) and N-DWCNTs (51.29 F/g) with current density 0.125 A/g.

Background: Implantation of saphenous vein (SV) grafts into coronary position determines structural vessel wall remodeling and intimal hyperplasia. The role of the altered wall mechanics and cell-based mechanosensing has been recently implicated in the priming of this pathologic process. We investigated the effects of cyclic uniaxial strain on human saphenous vein progenitor cells (SVPs), a cell type endowed with pericyte stem cell characteristics resident in the adventitia. Methods: CD34 + CD31 - SVPs were isolated with immuno-magnetic sorting (MACS) from SVs of patients (age 58±12.6, Mean±SD) undergoing saphenectomy. Cells were subject to uniaxial strain (10% elongation; 1Hz) for 24 and 72 hrs using the FlexCell system. Cell orientation, immunofluorescence and western analyses were performed to assess the effects of strain on cell orientation/shape, cell cycle and activity of the YAP/Hippo-dependent mechanotransduction machinery. RNA-sequencing from control vs. strained SVPs was performed at both time points using RNA from cells of 5 independent donors. Results: Results indicated an increase in the expression of the cell cycle-associated markers Ki67 and pHH3 in mechanically stimulated vs. control SVPs at 24 hrs, followed by a significant reduction at 72 hrs of stimulation. Variations in cell shape was observed as verified by a significant change in the nuclei orientation in the strain field as well as in the cell shape index/spread areas at both time points. Immunofluorescence revealed a significant increase in cells showing a nuclear localization of the YAP transcription factor at 72hrs. In line with these findings Western analyses indicated a significant decrease in the ratio between phosphorylated/total YAP and its upstream kinase LATS in mechanically stimulated vs. control SVPs, suggesting an inhibition of the HIPPO kinase pathway by mechanosensing. RNASeq gene expression analyses showed a coherent modification of gene expression pathways and the upregulation of a specific HIPPO/YAP/TEAD gene expression signature in SVPs mechanically stimulated for 72hrs. Conclusions: These findings demonstrate the direct susceptibility of human SVPs to pathologic strain and identifies this cell population as mechano-perceptors in the vein wall.

Pluripotency and commitment are driven by transcription factors that act as molecular switches to activate or repress specific gene expression programs. Among these, the POU transcription factor OCT4 (encoded by POU class 5 homeobox 1, POU5F1) is known to be a regulator in pluripotent cells and it is essential for the maintenance of a high plasticity state in mammalian cells. In recent years, particular attention has been given to the importance of physical extracellular matrix properties in regulating pluripotent cell maintenance and differentiation. In particular, recent studies demonstrated that high plasticity cells are intrinsically soft and respond optimally to physical forces when cultured on a “low stiffness” substrate that matches their intrinsic softness. To investigate these aspects, here we used a protocol where terminally differentiated cells are driven into a high plasticity/OCT4-positive state through the use of the epigenetic eraser, 5-aza-cytidine (5-aza-CR) and we observed the effect of substrate stiffness on the maintenance of OCT4 expression. To this purpose, human skin fibroblasts were plated either on standard plastic dishes (group A) or on polyacrylamide gels (PAA) of low stiffness (1 kPa; group B). Cells were treated with 1 μM 5-aza-CR for 18 h and were subsequently maintained and cultured in embryonic stem cell medium for 14 days. Assessment of OCT4 was carried out both by real-time PCR and immunocytochemical analysis, at different time points: untreated fibroblasts (T0), after 5-aza-CR treatment, and on Days 2, 4, 6, 8, 10, and 14 of culture. The results obtained indicate that untreated fibroblasts (T0) were negative for OCT4, whereas, after 5-aza-CR exposure, cells actively expressed the pluripotency marker, in both the A and B groups. However, whereas group A cells progressively down-regulated OCT4 expression and eliminated its positivity by Day 6, group B cells steadily transcribed and were homogeneously immunopositive for the pluripotency factor until Day 14, when cultures were arrested. Overall, the data obtained suggest that a soft substrate, matching the intrinsic stiffness distinctive of high plasticity cells, may help in promoting their maintenance, via a biophysical mechanism of low-traction/low-stiffness-dependent manner. Study was supported by Carraresi Foundation.