Power Consideration in the Pulsed Dielectric Barrier Discharge at Atmospheric Pressure

Nonequilibrium, atmospheric pressure discharges are rapidly becoming an important technological component in material processing applications. Amongst their attractive features is the ability to achieve enhanced gas phase chemistry without the need for elevated gas temperatures. To further enhance the plasma chemistry, pulsed operation with pulse widths in the nanoseconds range has been suggested. We report on a specially designed, dielectric barrier discharge based diffuse pulsed discharge and its electrical characteristics. Two current pulses corresponding to two consecutive discharges are generated per voltage pulse. The second discharge, which occurs at the falling edge of the voltage pulse, is induced by the charges stored on the electrode dielectric during the initial discharge. Therefore, the power supplied to ignite the first discharge is partly stored to later ignite a second discharge when the applied voltage decays. This process ultimately leads to a much improved power transfer to the plasma

Atmospheric pressure plasma analysis by modulated molecular beam mass spectrometry

Fractional no. d. measurements for a radiofrequency plasma needle operating at atm. pressure were obtained using a mol. beam mass spectrometer (MBMS) system designed for diagnostics of atm. plasmas. The MBMS system comprises three differentially pumped stages and a mass/energy analyzer and includes an automated beam-to-background measurement facility as a software-controlled chopper mechanism. The automation of the beam modulation allows the neutral components in the plasma to be rapidly and accurately measured using the mass spectrometer by threshold ionization techniques. Data are reported for plasma generated by a needle plasma source operated using a He/air mixt. In particular, data for the conversion of atm. O and N into nitric oxide are discussed with ref. to its significance for medical applications such as disinfecting wounds and dental cavities and for microsurgery. [on SciFinder (R)

High loading of nanostructured ceramics in polymer composite thick films by aerosol deposition

Low temperature fabrication of Al2O3-polyimide composite substrates was carried out by an aerosol deposition process using a mixture of Al2O3 and polyimide starting powders. The microstructures and dielectric properties of the composite thick films in relation to their Al2O3 contents were characterized by X-ray diffraction analysis. As a result, the crystallite size of α-Al2O3 calculated from Scherrer's formula was increased from 26 to 52 nm as the polyimide ratio in the starting powders increased from 4 to 12 vol.% due to the crushing of the Al2O3 powder being reduced by the shock-absorbing effect of the polyimide powder. The Al2O3-polyimide composite thick films showed a high loss tangent with a large frequency dependence when a mixed powder of 12 vol.% polyimide was used due to the nonuniform microstructure with a rough surface. The Al2O3-polyimide composite thick films showed uniform composite structures with a low loss tangent of less than 0.01 at 1 MHz and a high Al2O3 content of more than 75 vol.% when a mixed powder of 8 vol.% polyimide was used. Moreover, the Al2O3-polyimide composite thick films had extremely high Al2O3 contents of 95 vol.% and showed a dense microstructure close to that of the Al2O3 thick films when a mixed powder of 4 vol.% polyimide was used

Unexplored olive cultivars from the Valencian Community (Spain): some chemical characteristics as a valorization strategy

[EN] The olive processing industry has till date been dominated by a small group of cultivars, leading to the possibility of some olive cultivars becoming extinct in the near future. In this study, we determined the composition of some chemical components in the olive oils from 31 minor olive cultivars of the Valencian Community. Our main aim was to identify suitable cultivars, which could produce differentiated olive oils, thus aiming towards their valorization. The average oil content of minor olive cultivars was found to be good, with some of them reporting approximately 60% (dry basis). On average, the total phenolic content was 229mg kg(-1), with cv. Mas Blanc reporting the highest content (570mg kg(-1)). Among the various tocopherols found in olives, -tocopherol was the main constituent, with a maximum concentration of 290.6mg kg(-1). Linoleic acid was the main polyunsaturated fatty acid and varied between 3.4% (cv. Del Pomet) and 16.9% (cv. Blanqueta Enguera). Special attention needs to be paid to the composition of sterols, since some olive oils exceeded the limits established for some sterols by the current European legislation. Some of the cultivars studied were highly productive, and originated differentiated olive oils with a rich composition of antioxidants and essential fatty acids. In some cases, these beneficial compounds were higher than those of commercial oils obtained from the most common cultivars worldwide. These results could contribute to the commercial exploitation of some of the studied cultivars.Salazar-García, DC.; Malheiro, R.; Pereira, JA.; López- Cortés, I. (2019). Unexplored olive cultivars from the Valencian Community (Spain): some chemical characteristics as a valorization strategy. European Food Research and Technology. 245(2):325-334. https://doi.org/10.1007/s00217-018-3164-7S3253342452Avidan B, Birger R, Abed-El-Hadi F, Salmon O, Hekster O, Friedman Y, Lavee S (2011) Adopting vigorous olive cultivars to high density hedgerow cultivation by soil applications of uniconazole, a gibberellin synthesis inhibitor. Span J Agric Res 9:821–830Barranco D, Rallo L (2000) Olive cultivars in Spain. HortTechnology 10:107–110Navero DB (2000) World catalogue of olive varieties. International Olive Oil Council, MadridBorges TH, Pereira JA, Cabrera-Vique C, Lara L, Oliveira AF, Seiquer I (2017) Characterization of Arbequina virgin olive oils produced in different regions of Brazil and Spain: physicochemical properties, oxidative stability and fatty acid profile. Food Chem 215:454–462Laroussi-Mezghani S, Le Dréau Y, Molinet J, Hammami M, Grati-Kamoun N, Artaud J (2016) Biodiversity of Tunisian virgin olive oils: varietal origin classification according to their minor compounds. Eur Food Res Technol 242:1087–1099Kosma I, Vavoura M, Kontakos S, Karabagias I, Kontominas M, Apostolos K, Badeka A (2016) Characterization and classification of extra virgin olive oil from five less well-known Greek olive cultivars. J Am Oil Chem Soc 93:837–848Reboredo-Rodríguez P, González-Barreiro C, Cancho-Grande B, Valli E, Bendini A, Toschi TG, Simal-Gandara J (2016) Characterization of virgin olive oils produced with autochthonous Galician varieties. Food Chem 212:162–171Kyçyk O, Aguillera MP, Gaforio JJ, Jiménez A, Beltrán G (2016) Sterol composition of virgin olive oil of forty-three olive cultivars from the World Collection Olive Germplasm Bank of Cordoba. J Sci Food Agric 96:4143–4150Ruiz-Domínguez ML, Raigón MD, Prohens J (2013) Diversity for olive oil composition in a collection of varieties from the region of Valencia (Spain). Food Res Int 54:1941–1949Mateos R, Dominguez MM, Espartero JL, Cert A (2003) Antioxidant effect of phenolic compounds, α-tocopherol, and other minor components in virgin olive oil. J Agric Food Chem 51:7170–7175Hermoso M, Uceda M, García A, Morales B, Frias ML, Fernández A (1991) Elaboración de Aceite de Calidad. Consejeria de Agricultura y Pesca, SevillaMalheiro R, Rodrigues N, Bissaro C, Leimann F, Casal S, Ramalhosa E, Pereira JA (2017) Improvement of sensorial and volatile profiles of olive oil by addition of olive leaves. Eur J Lipid Sci Technol 119:1700177Commission Delegated Regulation (EU) 2016/2095 amending Regulation (EEC) No 2568/91 on the characteristics of olive oil and olive-residue oil and on the relevant methods of analysis. Off J Eur Union L:326Slover HT, Thompson RH, Merola GV (1983) Tocopherol and sterol determination by capillary gas chromatography. J Am Oil Chem Soc 60:1524–1528Sousa A, Casal S, Malheiro R, Lamas H, Bento A, Pereira JA (2015) Aromatized olive oil: Influence of flavouring in quality, composition, stability, antioxidants, and antiradical potential. LWT Food Sci Technol 60:22–28Limón P, Malheiro R, Casal S, Acién-Fernández FG, Fernández-Sevilla JM, Rodrigues N, Cruz R, Bermejo R, Pereira JA (2015) Improvement of stability and carotenoids fraction of virgin olive oil by addition of microalgae Scenedesmus almeriensis extracts. Food Chem 175:203–211Motilva MJ, Tovar MJ, Romero MP, Alegre S, Girona J (2000) Influence of regulated deficit irrigation strategies applied to olive trees (Arbequina cultivar) on oil yield and oil composition during the fruit ripening period. 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Bioactivity, chemistry and processing. Wiley, Hoboken, pp 81–116Shahzad N, Khan W, Shadab MD, Ali A, Saluja SS, Sharma S, Al-Allaf FA, Abduljaleel Z, Ibrahim IAA (2017) Phytosterols as a natural anticancer agent: current status and future perspective. Biomed Pharmacol 88:786–794Covas MI, Ruiz-Gutiérrez V, de la Torre R, Kafatos A, Lamuela-Raventós RM, Osada J, Owen RW, Visioli F (2006) Minor components of olive oil: evidence to date of health benefits in humans. Nutr Rev 64:S20–S30Pirodi M, Albini A, Fabiani R, Giovannelli L, Luceri C, Natella F, Rosignoli P, Rossi T, Taticchi A, Servili M, Galli F (2017) Nutrigenomics of extra-virgin olive oil: a review. Biofactors 43:17–41Franco MN, Galeano-Díaz T, Sánchez J, De Miguel C, Martín-Vertedor D (2014) Total phenolic compounds and tocopherols profiles of seven olive oil varieties grown in the South-West of Spain. 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Bacterial Inactivation of Wound Infection in a Human Skin Model by Liquid-Phase Discharge Plasma

Background: We investigate disinfection of a reconstructed human skin model contaminated with biofilm-formative Staphylococcus aureus employing plasma discharge in liquid. Principal Findings: We observed statistically significant 3.83-log10 (p,0.001) and 1.59-log10 (p,0.05) decreases in colony forming units of adherent S. aureus bacteria and 24 h S. aureus biofilm culture with plasma treatment. Plasma treatment was associated with minimal changes in histological morphology and tissue viability determined by means of MTT assay. Spectral analysis of the plasma discharge indicated the presence of highly reactive atomic oxygen radicals (777 nm and 844 nm) and OH bands in the UV region. The contribution of these and other plasma-generated agents and physical conditions to the reduction in bacterial load are discussed. Conclusions: These findings demonstrate the potential of liquid plasma treatment as a potential adjunct therapy for chronic wounds

Disinfection of Ocular Cells and Tissues by Atmospheric-Pressure Cold Plasma

Background: Low temperature plasmas have been proposed in medicine as agents for tissue disinfection and have received increasing attention due to the frequency of bacterial resistance to antibiotics. This study explored whether atmospheric-pressure cold plasma (APCP) generated by a new portable device that ionizes a flow of helium gas can inactivate ocular pathogens without causing significant tissue damage. Methodology and Principal Findings: We tested the APCP effects on cultured Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Candida albicans, Aspergillus fumigatus and Herpes simplex virus-1, ocular cells (conjunctival fibroblasts and keratocytes) and ex-vivo corneas. Exposure to APCP for 0.5 to 5 minutes significantly reduced microbial viability (colony-forming units) but not human cell viability (MTT assay, FACS and Tunel analysis) or the number of HSV-1 plaque-forming units. Increased levels of intracellular reactive oxygen species (ROS) in exposed microorganisms and cells were found using a FACS-activated 2',7'-dichlorofluorescein diacetate probe. Immunoassays demonstrated no induction of thymine dimers in cell cultures and corneal tissues. A transient increased expression of 8-OHdG, genes and proteins related to oxidative stress (OGG1, GPX, NFE2L2) was determined in ocular cells and corneas by HPLC, qRT-PCR and Western blot analysis. Conclusions: A short application of APCP appears to be an efficient and rapid ocular disinfectant for bacteria and fungi without significant damage on ocular cells and tissues, although the treatment of conjunctival fibroblasts and keratocytes caused a time-restricted generation of intracellular ROS and oxidative stress-related responses

Application of an electronic tongue for Tunisian olive oils' classification according to olive cultivar or physicochemical parameters

Olive oil commercialization has a great impact on the economy of several countries, namely Tunisia, being prone to frauds. Therefore, it is important to establish analytical techniques to ensure labeling correctness concerning olive oil quality and olive cultivar. Traditional analytical techniques are quite expensive, time consuming and hardly applied in situ, considering the harsh environments of the olive industry. In this work, the feasibility of applying a potentiometric electronic tongue with cross-sensitivity lipid membranes to discriminate Tunisian olive oils according to their quality level (i.e., extra virgin, virgin or lampante olive oils) or autochthonous olive cultivar (i.e., cv Chétoui and cv Shali) was evaluated for the first time. Linear discrimination analysis coupled with the simulated annealing variable selection algorithm showed that the signal profiles of olive oils hydroethanolic extracts allowed olive oils discrimination according to physicochemical quality level (classification model based on 25 signals enabling 84 ± 9% correct classifications for repeated K-fold cross-validation), and olive cultivar (classification model based on 20 signals with an average sensitivity of 94 ± 6% for repeated K-fold cross-validation), regardless of the geographical origin and olive variety or the olive quality, respectively. The results confirmed, for the first time, the potential discrimination of the electronic tongue, attributed to the observed quantitative response (sensitivities ranging from 66.6 to +57.7 mV/decade) of the E-tongue multi-sensors towards standard solutions of polar compounds (aldehydes, esters and alcohols) usually found in olive oils and that are related to their sensory positive attributes like green and fruity.This work was financially supported by Project POCI-01–0145-FEDER-006984–Associate Laboratory LSRE-LCM and by Project UID/QUI/00616/2013–CQ-VR both funded by FEDER—Fundo Europeu de Desenvolvimento Regional through COMPETE2020-Programa Operacional Competitividade e Internacionalização (POCI)—and by national funds through FCTFundação para a Ciência e a Tecnologia, Portugal. Strategic funding of UID/BIO/04469/2013 unit is also acknowledged. Nuno Rodrigues thanks FCT, POPH-QREN and FSE for the Ph.D. Grant (SFRH/ BD/104038/2014).info:eu-repo/semantics/publishedVersio

Chemical kinetics in an atmospheric pressure helium plasma containing humidity

Atmospheric pressure plasmas are sources of biologically active oxygen and nitrogen species, which makes them potentially suitable for the use as biomedical devices. Here, experiments and simulations are combined to investigate the formation of the key reactive oxygen species, atomic oxygen (O) and hydroxyl radicals (OH), in a radio-frequency driven atmospheric pressure plasma jet operated in humidified helium. Vacuum ultra-violet high-resolution Fourier-transform absorption spectroscopy and ultra-violet broad-band absorption spectroscopy are used to measure absolute densities of O and OH. These densities increase with increasing H 2 O content in the feed gas, and approach saturation values at higher admixtures on the order of 3 × 10 14 cm −3 for OH and 3 × 10 13 cm −3 for O. Experimental results are used to benchmark densities obtained from zero-dimensional plasma chemical kinetics simulations, which reveal the dominant formation pathways. At low humidity content, O is formed from OH + by proton transfer to H 2 O, which also initiates the formation of large cluster ions. At higher humidity content, O is created by reactions between OH radicals, and lost by recombination with OH. OH is produced mainly from H 2 O + by proton transfer to H 2 O and by electron impact dissociation of H 2 O. It is lost by reactions with other OH molecules to form either H 2 O + O or H 2 O 2 . Formation pathways change as a function of humidity content and position in the plasma channel. The understanding of the chemical kinetics of O and OH gained in this work will help in the development of plasma tailoring strategies to optimise their densities in applications

A first investigation for reducing e-learning environment complexity by Multiscale

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