In this study, we demonstrate an effective skin therapy device based on the plasma generated nitric oxide (NO) and needling techniques. The NO generator was constructed based on the dielectric barrier discharge plasma and combined with a commercial needling device. As a result, continueous flow of the NO could be supplied during needling treatment procedure. Several input voltages were investigated to generate plasma and study the optimum concentration of the generated NO. Furthermore, the synergetic effect of the NO exposure and needling technique to the collagen generation on the skin was analysed by both histological and gene expression methods on SKH-1 mice. Based on the histological examination, the samples treated with plasma showed an increased subcutaneous collagen density, and this effect was enhanced with a higher depth of needling. The differential gene expression of the Col4a5 gene was increased more than 100 times in the samples treated with a longer exposure of needling and plasma regardless of the depth. The results suggest that both needling and plasma treatment have a synergistic effect on the production of collagen which might be due mainly to the increased expression of the Col4a5 gene in the dorsal skin of SKH-1 mice.
The scope of this work is to determine and compare the effect of electron temperature (T e ) and number density (N e ) on the yield rate and concentration of reactive chemical species (• OH, H 2 O 2 and O 3 ) in an argon, air and oxygen injected negative DC (0-4 kV) capillary discharge with water flow(0.1 L/min). The discharge was created between tungsten pin-to pin electrodes (Φ = 0.5 mm) separated by a variable distance (1-2 mm) in a quartz capillary tube (2 mm inner diameter, 4 mm outer diameter), with various gas injection rates (100-800 sccm). Optical emission spectroscopy (OES) of the hydrogen Balmer lines was carried out to investigate the line shapes and intensities as functions of the discharge parameters such as the type of gas, gas injection rate and inter electrode gap distances. The intensity ratio method was used to calculate T e and Stark broadening of Balmer β lines was adopted to determine N e . The effects of T e and N e on the reactive chemical species formation were evaluated and presented. The enhancement in yield rate of reactive chemical species was revealed at the higher electron temperature, higher gas injection rates, higher discharge power and larger inter-electrode gap. The discharge with oxygen injection was the most effective one for increasing the reactive chemical species concentration. The formation of reactive chemical species was shown more directly related to T e than N e in a flowing water gas injected negative DC capillary discharge.
Polyoxymethylene copolymer (POM-C) round block was implanted with 120 KeV ions of He to doses of 5 x 10 16 and 1 x 10 16 ions cm -2. It was also implanted with 120 KeV ions of Ar + He and He + Ne to dose of 1 x 10 16 ions cm -2, respectively. The friction coefficient behavior of both implanted and unimplanted POM-C blocks was investigated using a ball on disk tribometer mechanism. The friction coefficient of He ion implanted POM-C block at a dose of 5 x 10 16 ions cm -2 is lowest compared to all unimplanted and others ions doses implanted POM-C blocks. It also shows the moderate surface texturing (atomic rearrangement), lower surface micro-hardness and average surface roughness compared to both unimplanted and other ions doses implanted POM-C blocks due to well adjusted carbonization, cross-linking and ions-target atoms collisions, which is ascertained from SEM-EDS, Raman spectroscopic and surface profiling observations. The other ions doses implanted POM-C blocks demonstrate the higher friction coefficient and surface roughness with polymer surface deformation (crazing, cracking, pitting and gas evolution, bond breaking) due to severe chain scission, surface dose delivered atomic displacements and chemical structural degradation. It is concluded that the variation in friction coefficient behavior of POM-C block resulted from its structural response for ion beam implantation on the top surface.
Polyoxymethylene copolymer (POM-C) is the most prominent engineering thermoplastic consisting of repeating carbon-oxygen bonds in the form of oxymethylene groups (OCH 2 ). It is widely used to make small gear wheels, ball bearings, precision parts, automotive and consumer electronics. In this study, the POM-C round blocks were irradiated with 165 KeV electron beam energy in five doses (100, 200, 300, 500 and 700 kGy) in vacuum condition at room temperature. The wear rate, surface hardness and morphological properties of electron beam dose irradiated POM-C blocks surfaces have been analyzed using pin on disk tribometer, optical microscopy, nano-indenter, Raman spectroscopy, 3D nano surface profiler and scanning electron microscopy (SEM). The electron beam irradiation transferred the wear phenomena of unirradiated POM-C sample from the abrasive wear (plough and cracks), adhesive wear (grooving/striation, micropitting) and scraping to mild scraping and striation for the 100 kGy dose irradiated POM-C sample due to cross-linking (macroscopic networks), chemical free radicals formations and partial physical modification (smoothness), which can be concluded from tribometer, optical microscopic, SEM and Raman spectroscopic observations. It also reduced the surface wear rate and average surface roughness with increasing microsurface hardness at threshold value of cross-linking among all unirradiated and others doses irradiated POM-C blocks. The level of tribological (wear and morphology) attribute improvement relies on the electron beam irradiation condition (energy and dose rate) depending on chemical and physical factors of polymeric materials.
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