Inactivation of isolated fungi on Erythrina velutina Willd. seeds through atmospheric plasma

This study aimed to evaluate the effect of atmospheric plasma application on the inactivation of fungi on the surface of Erythrina velutina seeds and on isolated fungal colonies. Two experiments were conducted using a completely randomized design. First, plasma was applied to the surface of the seeds using helium gas and atmospheric plasma for 3, 6, and 9 min in addition to the control (untreated seeds), constituting seven treatments with five repetitions each. In the second experiment, Petri dishes containing the inoculum of different fungi were treated with atmospheric air plasma for 3, 6, and 9 min (Air-3, Air-6, and Air-9) and were compared with untreated fungi in Petri dishes without treatment (control), totaling four treatments and five repetitions each. We found that the application of atmospheric air plasma to E. velutina seeds for 9 min had an antimicrobial effect on the fungi Aspergillus niger, Aspergillus flavus, Fusarium sp., Brachysporium sp., and Rhizopus sp. The formation of fungal colonies isolated from E. velutina seeds was also inhibited by 3 min of exposure to atmospheric air plasma, except for A. niger, whose inhibition occurred after 6 min of exposure to atmospheric plasma.

Activation and transmutation of tungsten boride shields in a spherical tokamak

The FISPACT-II code is used to compute the levels of activation and transmutation of tungsten borides for shielding the central High Temperature Superconductor (HTS) core of a spherical tokamak fusion power plant during operations at 200 MW fusion power for 30 years and after shutting down for 10 years. The materials considered were W2B, WB, W2B5 and WB4 along with a sintered borocarbide B0.329C0.074Cr0.024Fe0.274W0.299, monolithic W and WC. Calculations were made within shields composed of each material, for five reactor major radii from 1400 to 2200 mm, and for six 10B isotope concentrations and at five positions across the shield. The isotopic production and decay in each shield is detailed. The activation of boride materials is lower than for either W or WC and is lowest of all for W2B5. While isotopes from tungsten largely decay within 3 years of shut-down, those from boron have a much longer decay life. An acceptable 70% of the absorbing 10B isotope will remain after 30 years of operations behind the first wall for a 1400 mm radius tokamak. Gaseous production is problematic in boride shields, where 4He in particular is produced in quantities 3 orders of magnitude higher than in W or WC shields. The FISPACT-II displacements per atom (dpa) tend to increase with boron content, although they decrease with increased 10B isotopic content. The dpa ranges of boride shields tend to lie between those of W and WC. Overall, the results confirm that the favourable fusion reaction shielding properties of W2B5 are not seriously challenged by its irradiation and transmutation properties, although helium gas production could be a challenge to its thermal and mechanical properties.

On shock-induced light-fluid-layer evolution

Shock-induced light-fluid-layer evolution is firstly investigated experimentally and theoretically. Specifically, three quasi-one-dimensional helium gas layers with different layer thicknesses are generated to study the wave patterns and interface motions. Six quasi-two-dimensional helium gas layers with diverse layer thicknesses and amplitude combinations are created to explore the Richtmyer–Meshkov instability of a light-fluid layer. Due to the multiple reflected shocks reverberating inside a light-fluid layer, the speeds of the two interfaces gradually converge, and the layer thickness saturates eventually. A general one-dimensional theory is adopted to describe the two interfaces’ motions and the layer thickness variations. It is found that, for the first interface, the end time of its phase reversal determines the influence of the reflected shocks on it. However, the reverberated shocks indeed lead to the second interface being more unstable. When the two interfaces are initially in phase, and the initial fluid layer is very thin, the two interfaces’ spike heads collide and stabilise the two interfaces. Linear and nonlinear models are successfully adopted by considering the interface-coupling effect and the reverberated shocks to predict the two interfaces’ perturbation growths in all regimes. The interfacial instability of a light-fluid layer is quantitatively compared with that of a heavy-fluid layer. It is concluded that the kind of waves reverberating inside a fluid layer significantly affects the fluid-layer evolution.

Applications of Helium Plasma in Rejuvenation of the Face and Neck

Energy based devices have been developed for the purposes of tissue contraction and skin tightening. Its application in the face and neck have been explored using lasers, temperature controlled monopolar and bipolar radiofrequency, and ultrasound. The purpose of this chapter is to explore the various applications for the face and neck using Renuvion™, a unique energy driven device based on plasma generated from the combination of helium gas and radiofrequency energy. The advantage of this technology is its ability to offer precise delivery of heat to tissue with minimal thermal spread, in part due to the rapid cooling aided by the helium gas. We will explore the options in which this technology can be incorporated to rejuvenate the face and neck, the patient selection considerations in choosing method of approach, surgical technique, anticipated outcomes, potential concerns and or complications associated with this and expected perioperative care. Applications in the face and neck include: (1) Subdermally in the neck as a stand alone procedure with or without liposuction. (2) Subdermally in a limited incision, non-excisional technique with a concomitant platysmaplasty either with an open approach or percutaneous use of suture suspension for the platysmal muscle. (3) Subdermally in conjunction with an open traditional rhytidectomy involving skin excision. (4) Ablative resurfacing—fractional or pulsed and full continuous modalities (non-FDA cleared at the time of this writing). It is the authors’ experience that with appropriate patient selection this can be a powerful tool that can deliver skin tightening and rhytid reduction not seen by other technologies available.

The Effect of Cold Atmospheric Plasma on the Expression of Apoptotic Genes in Breast Cancerous Cells

Background: Breast cancer is one of the most malignant cancers in the world. Cold micro plasma jet (CMPJ) Known as cold atmospheric jet microplasma, it has recently been introduced as an alternative way to overcome the challenges of finding an effective cancer treatment. Numerous studies have reported promising results, so our aim of this study was to investigate how this method affects cell death and its role on the expression of apoptotic genes in the MCF-7 cancer cell line. Methods: In this study, helium gas was used to generate plasma at room temperature in the form of point radiation at different times of 30, 60, 90 and 120 seconds and at different distances of 1 cm. Flow cytometry will be used to examine the extent of apoptosis and necrosis. Genes involved in apoptosis P53, P21, Bax and Bcl-2 were measured by real-time PCR. Results: Our Studie indicate that the mechanism of action of cold plasma on cancer cells is related to generation of reactive oxygen species with possible induction of the apoptosis pathway. The percentages of necrotic and late apoptotic cells following treatment with different times plasma (0, 30, 60, 90 and 120 s) were about 0.55 ± 0.06, 20.13 ± 0.01, 20.12 ± 0.03, 26.81 ± 0.04 and 17.51 ± 0.05. The mRNA expression of bcl-2 showed a decrease of 90s of plasma while the mRNA expression of p53, bax and caspase-8 genes increased compared to untreated cells. Conclusion: In general, research in the last decade has confirmed the ability of CMPJ as an effective anti-cancer tool. Therefore, it may be used to help treat cancer. However, its clinical application requires much further studies to determine the severity and duration of exposure to CMPJ for effective treatment based on the type of cancer.

Accurate Electron Drift Mobility Measurements in Moderately Dense Helium Gas at Several Temperatures

We report new accurate measurements of the drift mobility μ of quasifree electrons in moderately dense helium gas in the temperature range 26K≤T≤300K for densities lower than those at which states of electrons localized in bubbles appear. By heuristically including multiple-scattering effects into classical kinetic formulas, as previously done for neon and argon, an excellent description of the field E, density N, and temperature T dependence of μ is obtained. Moreover, the experimental evidence suggests that the strong decrease of the zero-field density-normalized mobility μ0N with increasing N from the low up to intermediate density regime is mainly due to weak localization of electrons caused by the intrinsic disorder of the system, whereas the further decrease of μ0N for even larger N is due to electron self-trapping in cavities. We suggest that a distinction between weakly localized and electron bubble states can be done by inspecting the behavior of μ0N as a function of N at intermediate densities.