Background. Polytetrafluoroethylene (PTFE) patch is commonly used during surgical closure for atrial septal defect (ASD) and/or ventricular septal defect (VSD). It has several limitations such as inability to grow, repair, and remodel. Aneurysm formation, thrombosis, and the inability of patches to grow or remodel are usual, especially in children and young adults. To tackle these limitations, we try to use fibronectin and human adipose-derived mesenchymal stem cells (hAMSCs) in PTFE patch. Objective. To understanding positive impact of fibronectin to enhance hAMSCs cell-to-cell adherence and cell-to-patch surface attachment into PTFE patch for future ASD or VSD closure. Methods. Cultured of hAMSCs cells were fixated with 15 mL methanol and CD90+, CD105+, CD45- antibodies were labeled FITC, rinsed with PBS and analyzed under fluorescence microscope for 15 minutes. Fibronectin solution 0.1% were used to soak patch scaffolds for approximately 2 hours duration, and then dried for 20 minutes for treatment group. As for control group, Fibronectin solution was not added on the culture. The samples were examined with scanning electron microscope (SEM). Results. SEM examination showed incomplete attachment of the cells even after 10 days on control group at 1.14 ±1.13 (Figure 2). In contrast, treatment group showed more cells attached to the patch surface at 31.25 ±13.28 (p 0.000) (Figure 3). Observation at 5 days was 17.67 ± 20.21, at 7 days was 12.11 ± 10.94, at 10 days was 18.83 ± 23.25. No significant statistical difference of mean cell per view among each treatment group (p 0.802). Conclusion. Fibronectin has a positive impact on hAMSCs attachment seeded onto PTFE patch. These properties, in combination with their developmental plasticity, have generated tremendous interest because of the potential use of hAMSCs in regenerative medicine to replace damaged tissues.

This paper presents results on tribological characteristics for polymer blends made of polybutylene terephthalate (PBT) and polytetrafluoroethylene (PTFE). This blend is relatively new in research as PBT has restricted processability because of its processing temperature near the degradation one. Tests were done block-on-ring tribotester, in dry regime, the variables being the PTFE concentration (0%, 5%, 10% and 15%wt) and the sliding regime parameters (load: 1 N, 2.5 N and 5 N, the sliding speed: 0.25 m/s, 0.5 m/s and 0.75 m/s, and the sliding distance: 2500 m, 5000 m and 7500 m). Results are encouraging as PBT as neat polymer has very good tribological characteristics in terms of friction coefficient and wear rate. SEM investigation reveals a quite uniform dispersion of PTFE drops in the PBT matrix.

The spray drying process causes the buildup of an unspecified and unique pattern of wall deposits on the wall. The powder recovery of fruit juice by spray dryer is associated with stickiness problems because of the nature of food which contains low molecular weight sugars and organic acids, which have a low glass transition temperature (T_g). The surface properties of oxygen plasma treated-PTFE substrate were evaluated by using the different parameters of Plasma Enhanced Chemical Vapour Deposition (PECVD) prior to spray drying analysis. In this study, the fabrication method of nearly perfect superhydrophobic surfaces through plasma treatment with oxygen gas was generated and utilized. The plasma-treated PTFE were deposited from a fixed flow rate of oxygen gas with 30 cm³/min by varying the deposition time from 1 to 15 minutes to induce the hydrophobic surface of the PTFE substrate. The characterization techniques used to determine the morphology and chemical bonding of the substrate are field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopy (FTIR), respectively. The hydrophobicity of the glass samples was determined by the water droplet contact angle. Sample prepared at radio frequency (RF) power of 90W for 15 minutes duration of treatment time showed porous and spongy like microstructure which correlates with the best performance of a good contact angle which creates the superhydrophobicity regime (171^o). Surface morphology analysis using scanning electron microscopy (SEM) showed changes in its roughness in the surface-treated glass substrate. The success of this method produced a huge potential for solving most of the food processing issues which relate to biofouling (e.g., powder stickiness) that would otherwise struggle to improve high productivity and recovery.

In this paper, we describe the surface modification of Polytetrafluoroethylene (PTFE) through plasma treatment process. Several parameters including different active gases; RF power; dis-tance between the plasma source and sample; and plasma duration were optimized to reduce the hydrophobic nature of PTFE. Three different active gases were used [i.e., N2, O2 and (Ar+H2)], in which N2 was effective to reduce the hydrophobicity of PTFE within shorter plasma duration of 2 minutes. Several surface characterizations including ATR-FTIR, water contact angle, FE-SEM and XPS were utilized to verify the neat and modified PTFE surface after plasma treatment. The plasma treatment using N2 as an active gas improved the wettability of PTFE membrane, show-ing a water contact angle of 108° when compared with the neat PTFE (140°). The SEM images of plasma treated PTFE shows greater modifications on the surface indicating non-uniform fiber alignment and torn fibers at several places. The obtained results confirm the fact that plasma treatment is an effective way to modify the PTFE surface without altering its bulk property.

Wall–stabilized arcs dominated by nozzle–ablation are key elements of self–blast circuit breakers. In the present study, high–current arcs were investigated using a model circuit breaker (MCB) in CO2 as gas alternative to SF6 and in addition a long polytetrafluoroethylene nozzle under ambient conditions for stronger ablation. The assets of different methods for optical investigation were demonstrated, e.g. high-speed imaging with channel filters and optical emission spectroscopy. Particularly the phase near current zero (CZ) crossing was studied in two steps. In the first step using high-speed cameras, radial temperature profiles have been determined until 0.4 ms before CZ in the nozzle. Broad temperature profiles with a maximum of 9400 K have been obtained from analysis of fluorine lines. In the second step, the spectroscopic sensitivity was increased using an intensified CCD camera, allowing single-shot measurements until few microseconds before CZ in the MCB. Ionic carbon and atomic oxygen emission were analyzed using absolute intensities and normal maximum. The arc was constricted and the maximum temperature decreased from >18000 K at 0.3 ms to about 11000 K at 0.010 ms before CZ. The arc plasma needs about 0.5-1.0 ms after both the ignition phase and the current zero crossing to be completely dominated by the ablated wall material.

Molecule radiation can be used as a tool to study colder regions in switching arc plasmas like arc fringes in contact to walls and ranges around current zero (CZ). This is demonstrated in the present study for the first time for the case of ablation-dominated high–current arcs as key elements of self–blast circuit breakers. The arc in a model circuit breaker (MCB) in CO2 with and an arc in a long nozzle under ambient conditions with peak currents between 5 and 10 kA were studied by emission and absorption spectroscopy in the visible spectral range. The nozzle material was polytetrafluoroethylene (PTFE) in both cases. Imaging spectroscopy was carried out either with high-speed cameras or with intensified CCD cameras. A pulsed high-intensity Xe lamp was applied as background radiator for the broad-band absorption spectroscopy. Emission of Swan bands from carbon dimers was observed at the edge of nozzles only or across the whole nozzle radius with highest intensity in the arc center, depending on current and nozzle geometry. Furthermore, absorption of C2 Swan bands and CuF bands were found with the arc plasma serving as background radiator. After CZ, only CuF was detected in absorption experiments.