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INTRODUÇÃO: A medicina do plasma tem despontado como uma tecnologia em saúde viável e resolutiva na cicatrização de feridas. OBJETIVO: Comparar o efeito do modo contínuo e pulsado de aplicação do plasma atmosférico frio na cicatrização de feridas cutâneas agudas em porquinhos da índia. MÉTODOS: Foram utilizados 24 animais divididos em quatro grupos e submetidos a realização de 3 feridas no dorso, sendo ao mesmo tempo, experimento e controle segundo aprovação da CEUA (parecer nº 33/2020). Uma ferida foi controle, outra recebeu tratamento no modo contínuo e outra pulsado (10 Hz). O jateamento foi de 1 minuto em cada ferida com gás hélio 2L/ min, imediatamente após a cirurgia e a cada 24 horas por 3 dias consecutivos. Todas as feridas foram fotografadas a partir do dia 0 e analisadas no software Image J. Além do processamento histológico. RESULTADO: A média da taxa de retração das feridas controle nos dias 3, 7, 14 e 21 foi 30,91; 38,5; 89,16; 96,32. Já no grupo contínuo foi de 45,36; 51,95;91,40; 98,13. E no pulsado 54,20; 57,5; 95,74; 99,1, respectivamente. A taxa de retração dos grupos tratados foi significativamente maior que no controle. No dia 7, foi possível visualizar o processo de reepitelização, que se completou no dia 14 nas feridas tratadas com a epiderme e o estrato córneo espessos. No grupo controle, foi possível visualizar isto a partir do dia 14 e a epiderme e o estrato córneo estavam delgados. Não foi mais encontrado tecido de granulação nos tecidos tratados no dia 14, e no controle encontrou-se nos dias 14 e 21. DISCUSSÃO: de maneira geral a literatura aponta para um efeito benéfico do CAP no processo de cicatrização de feridas tanto quantitativamente, como qualitativamente. CONCLUSÃO: O uso do CAP promoveu uma redução do tempo e melhora qualitativa no processo de cicatrização.

INTRODUÇÃO: O plasma atmosférico frio (CAP) vem emergindo como tratamento promissor para o tratamento de lesões cutâneas, possuindo capacidade antimicrobiana e antinflamatória. Recentemente vem sendo utilizado no tratamento de neoplasias, promovendo a morte seletiva de células cancerígenas por meio da produção de espécies reativas de oxigênio e nitrogênio (ERON). Dentre os cânceres de pele não melanoma, o carcinoma de células escamosas (CCE) é o segundo mais prevalente, especialmente no nordeste do Brasil, onde há alta incidência solar. Os gatos são excelentes modelos para estudos de CCE, pois também frequentemente desenvolvem esse tipo de neoplasia, que possui comportamento semelhante. OBJETIVO: Dessa forma, objetivou-se avaliar o efeito do CAP sobre lesões de CCE em gato atendido no Hospital Veterinário Jerônimo Dix-Huit Rosado Maia – HOVET/UFERSA. MÉTODOS: Um felino, macho, adulto, com quatro lesões faciais (plano nasal, ponta da orelha, lábio inferior e canto medial do olho) foi submetido a dois ciclos de tratamento com CAP. Cada ciclo consistiu na administração do plasma por três vezes dentro de uma semana, seguido por uma semana sem exposição. O paciente foi acompanhado para avaliação da resposta ao tratamento e efeitos adversos. RESULTADOS: Com dois ciclos de tratamento foi possível observar resposta completa para as formações menores (canto medial do olho e ponta da orelha). O tumor em plano nasal apresentou resposta parcial e o CCE labial permaneceu estável. Os efeitos adversos foram leves, autolimitantes e incluíram eritema e formação de crostas. CONCLUSÃO: O CAP demonstrou-se eficaz para o tratamento do CCE cutâneo felino, principalmente em lesões superficiais. Para formações mais proliferativas, como em lábio inferior, podem ser necessárias estratégias multimodais de tratamento, a fim de permitir uma maior penetrabilidade das ERON.

Selective coatings are produced with high absorption in the ultraviolet/visible range, composed of ilmenite deposited on stainless steel substrates and aluminum substrates, using the cathodic cage plasma nitriding/deposition technique, for application in solar thermal absorbers. Ilmenite was initially characterized by means of X-ray fluorescence, X-ray diffractometry and thermal analysis. The coatings produced were optically characterized in the UV/Vis range, the microstructural evaluation of coatings was by scanning electron microscopy and data on the roughness parameters of the films produced were obtained by optical profilometry. Uniform selective surfaces with high solar absorbance (87 %) were obtained in the ilmenite samples deposited on stainless steel substrate.

The effects of cold atmospheric plasma (CAP) of dielectric barrier discharges on the wettability, imbibition and germination ofLeucaena leucocephalawere investigated. It was established that CAP treatment markedly hydrophilized the seed coat, especially at longer treatment times. From the profile of the imbibition curve and visual observation, it was possible to verify that there are two resistance barriers to water penetration: integument surface and region of the macrosclereid cell wall (light line). Although the plasma interacts only in the integument, increasing the density of hydrophilic sites increases the capacity of water absorption, producing enough driving force to overcome the second resistance barrier. The existence of these two barriers changes the three-phase pattern generally observed during seed germination. Despite an increase in imbibition, the plasma treatment conditions used in this work, were not enough to overcome completely the dormancy barrier.

The enzymatic oxidation process that causes black spots on shrimp, named melanosis, leads to spoilage and economic losses. Therefore, there is an urgent need for strategies to reduce melan...

Plasma electrolytic oxidation (PEO) is an environmentally friendly anodizing technique that produces ceramic coatings using high voltage discharges. To the present work this technique was applied to treat aluminum surfaces using a pulsed current supply and sodium silicate electrolyte. The effect of the duty cycle and treatment time on the morphology, phase composition and tribo-mechanical properties of the formed layer was investigated. The current density was maintained at 12 A/dm2, with two different duty cycles, 30% and 50%, for total period of 100 μs. For each duty cycle two different treatment times (2 min and 12 min) was used. During each treatment, the voltage was monitored to determine the start of the rupture of the passive oxide layer. It was demonstrated that the increase in the duty cycle from 30% to 50% influenced the thickness and porosity of the film, verified by scanning electron microscopy (SEM) images. Phase γ-Al2O3 was predominant on the surface of the samples treated by PEO, although occurrence of mullite and α-Al2O3 were also observed. There was an inversion in the intensities of the diffraction peaks Al (200) and Al (111) after the formation of the oxide phase, suggesting a preferential oxidation in the Al (111) direction. The PEO process allows tuning of the hardness, yield strength and wear resistance by controlling film thickness, porosity and phases present. Keywords: PEO, Plasma, Duty cycle, Aluminum oxide, Nanohardness, Wear rate

A titanium surface nitrided by plasma contains nitrogen ions that guarantee resistance to corrosion and biocompatibility. Despite this, no descriptions concerning the influence of the expression of cell adhesion proteins and their influence on osteogenic cell differentiation are available. Thus, the present study aimed to assess the response of murine pre‐osteoblastic cells (MC3T3‐E1) cultured on nitrided titanium surfaces. Pre‐osteoblastic cells were grown on polished titanium discs, used as controls, and on previously characterized plasma‐nitrided titanium discs. Cells from both groups were submitted to the MTT cell viability test. The expressions of α5, α2, and β1 integrin were assessed by flow cytometry and immunofluorescence, while osteocalcin expression was assessed by flow cytometry. The nitrided surface presented higher α2 and β1 integrin expressions, as well as osteocalcin expression, when compared to the polished surface, with no alterations in cell viability. These findings seem to suggest that the plasma nitriding treatment produces a titanium surface with the potential for effective in vitro osseointegration.

RESUMO Cera de carnaúba é utilizada, com sucesso, em revestimento de frutos por formar uma barreira contra a perda de umidade, troca de gases e ação antimicrobiana. No presente trabalho, pretende-se melhorar esta última propriedade através do tratamento por plasma. Plasma produzido por descarga de barreira dielétrica (DBD), usando pulsos de voltagem de 45 kV, repetidos na frequência de 405 Hz, durante 9 min, foi aplicado diretamente sobre esporos de fungo Colletotrichum brevisporum (4x104 conidia.cm-1) ou sobre superfície dos revestimentos de cera. Verificou-se que o revestimento, após tratado por plasma, apresentou resistência antifúngica equivalente àquela existente quando aplicada diretamente sobre os fungos. Este resultado foi justificado com base na literatura, em que o tratamento com plasma em lipídios estimula a oxidação das cadeias lipídicas, resultando na formação de compostos carboxílicos, que possuem propriedades antimicrobianas. ABSTRACT Carnauba wax is successfully used in fruit coating to produce a barrier against moisture loss, gas exchange and microbial action. The present study aims to improve this latter property by plasma treatment. Plasma produced by dielectric barrier discharge (DBD), using voltage pulses of 45 kV, repeated at the frequency of 405 Hz, for 9 min, was applied directly to spores of the fungus Colletotrichum brevisporum (4x104 conidia.cm-1) or on the surface of wax coatings. It was found that the coating, after being treated by plasma, presented antifungal resistance equivalent to that existing when applied directly to the fungi. This result was justified based on the literature, in which plasma treatment with lipids stimulates the oxidation of lipid chains, resulting in the formation of carboxylic compounds, which have antimicrobial properties.

Sob condicoes ainda desconhecidas, cristais denominados de flor de sal, ou fleur de sel, como e comumente conhecido, pode ser formado na superficie de uma salmoura supersaturada durante a evaporacao da agua do mar nas salinas. Visando produzir flor de sal de uma maneira controlada e fazer melhor uso da solucao residual de salinas, denominada de agua-mae, o presente trabalho foi proposto. O mecanismo de crescimento, morfologia, microestrutura e composicao quimica dos sais obtidos foram estudados durante a evaporacao da agua-mae, cuja densidade variou de 1,230 g/cm³ para 1,244 g/cm³, mantendo fixos o gradiente termico e umidade relativa do ar. Analises quimicas, microestruturais e morfologicas foram usadas para caracterizacao. Cristais cubicos ocos foram obtidos cujas concentracoes ionicas foram dependents da densidade da solucao. O tamanho e massa dos cristais tambem foram dependentes da densidade da solucao. As amostras apresentaram fases contendo sulfatos como NaK3(SO4)2, Mg (SO4). (H2O) e K2SO4, cuja porcentagem aumentou levemente com o aumento da densidade. Mesmo assim, as porcentagens de NaCl foram acima de 90% para todas as amostras, mostrando que e possivel extrair flor de sal de alta pureza a partir de uma solucao residual hipersalina. Palavras chaves: flor de sal, agua-mae, crescimento de cristais, mecanismo, salina.

A 12.4 kDa laminarin (LM) composed of &beta, (1&rarr, 3)-glucan with &beta, 6)-branches was extracted from brown seaweed Lobophora variegata and modified via carboxylation using dielectric barrier discharge (LMC), conjugation with gallic acid (LMG), and sulfation (LMS). Analyses of the chemical composition of LMC, LMG, and LMS yielded 11.7% carboxyl groups, 1.5% gallic acid, and 1.4% sulfate content, respectively. Antioxidant activities of native and modified laminarins were assessed using six different in vitro methods. Sulfation stopped the antioxidant activities of LM. On the other hand, carboxylation improved cooper chelation (1.2 times). LMG was found to be a more efficient antioxidant agent than LM in terms of copper chelation (1.3 times), reducing power (1.3 times), and total antioxidant capacity (80 times). Gallic acid conjugation was further confirmed using Fourier transform infrared spectroscopy (FT-IR) and one- and two-dimensional NMR spectroscopy analyses. LMG also did not induce cell death or affect the cell cycle of Madin&ndash, Darby canine kidney (MDCK) cells. On the contrary, LMG protected MDCK cells from H2O2-induced oxidative damage. Taken together, these results show that LMG has the potent antioxidant capacity, and, therefore, potential applications in pharmacological and functional food products.

Up to now, plasma electrolytic oxidation (PEO) has been either produced direct current or ultra-low frequency (< 1 kHz) pulsed discharge using high concentration alkaline-silicate electrolytic (Na2SiO3 > 8 g.L-1 with presence of KOH). In order to contribute to these studies, the effect of current pulse width and time duration was investigated using diluted silicate electrolytic (Na2SiO3 2 g.L-1) and high pulse frequencies (> 1 kHz). The PEO process was performed on pure aluminum to try to explain how the phases composing the coatings are formed and distributed over the treatment time. For this, was made in situ monitoring using optical emission spectroscopy (OES) coupled with CCD camera. The crystalline phases evolution in the sample surface was investigated using grazing incidence X-ray diffraction (GIXRD). Regarding the evolution of ceramic phases, it is possible to verify that, internally, the predominant phase is rhombohedral α-Al2O3 but, superficially, the predominant phase is cubic γ-Al2O3. It was verified the presence of Si on the borders of the pores or in proximity to cracks, especially in the treatments with higher pulse width. SEM analysis shows a reduction of the superficial porosity and an increase in coating thickness with pulse width and treatment time.

In this study, we analyzed seed wettability as well as imbibition and germination after treatment with atmospheric pressure cold plasma (APCP) using dielectric barrier discharge (DBD) in seeds that have very low germination rates. To aid industrial applications, several seeds were simultaneously treated with plasma within a space between two coaxial glass tubes sandwiched by two metal mesh screens that produced high-voltage pulses at 17.5 kV with a frequency of 990 Hz. Three treatment times (3 min, 9 min and 15 min) as well as untreated seeds were used to conduct the wettability, imbibition and germination tests. The wettability and imbibition were found to be directly related to the treatment duration, but saturation of the imbibition was found for treatment durations greater than 9 min. Plasma treatment was also effective in improving germination, but shorter treatment duration presented greater germination. This apparent contradiction is explained by the cell damage caused by the increased exposure to plasma, as observed in other studies. The results suggest that there must be an optimal wettability and imbibition condition that ensures that excessive moisture does not harm the germination process.

Direct current (DC) plasma nitriding offers some disadvantages, especially in parts with complex geometries, where the presence of edges is significant, such as gears, molds, and needle punched parts are strongly affected by this effect, leading to irregular formation of nitrided layers and high variation in surface hardness. To solve these problems two techniques were developed as alternatives, namely: pulsed plasma nitriding and cathodic cage nitriding. In this work, these three nitriding techniques were compared using AISI 1045 steel as substrate. Steel discs were nitrided with the purpose of evaluating the influence of these different plasma configurations on the characteristics of the nitrided layer. The treatments in the three techniques were carried out at the same pressure, temperature, time and gas atmosphere. The samples were characterized for the microstructure, microhardness and crystalline phases present. X-ray diffraction with grazing incidence was used to verify the order of the nitrites formed and to estimate the thickness of the single-phase layers. Differences between the configurations with respect to the occurrence of restriction rings, total thickness (xe + xγ') and relative (xe/xγ') compound layers were observed. Keywords: Plasma DC; cathodic cage; pulsed plasma; nitriding; GIXRD.

Objectives To evaluate the effects of the surface modification of 316L stainless steel (SS) by lowtemperature plasma nitriding on endothelial cells for stent applications. Results X-ray diffraction (XRD) confirmed the incorporation of nitrogen into the treated steel. The surface treatment significantly increased SS roughness and hydrophilic characteristics. After 4 h the cells adhered to the nitride surfaces and formed clusters. During the 24 h incubation period, cell viability on the nitrided surface was higher compared to the polished surface. Nitriding reduced late apoptosis of rabbit aorta endothelial cell (RAEC) on the SS surface. Conclusion Low temperature plasma nitriding improved the biocompatible of stainless steel for use in stents.

In the present work, Al2O3/ZrO2 nanocomposite surfaces were treated with cold plasma using N 2 , H 2 , and O 2 gaseous atmospheres. For this, Al2O3/ZrO2 samples were shaped and sintered at 1500 °C for 2 h. Then, the surfaces were treated with cold plasma using different N 2 and O 2 gas flow proportions. The H 2 gas flow was maintained at 50%. The treatment conditions were a total gas flow rate of 20 sccm, total pressure of 2.0 mbar, square pulses of voltage with duration of the 50 µs repeated every 100 µs, and a temperature of 400 °C. The surface treatment, regardless of the gaseous atmospheres, affected the functional groups attributed to ZrO2 significantly more than those of Al2O3. In general, it was observed that the surfaces treated in gaseous atmospheres with a higher proportion of N 2 gas flow had a more hydrophilic character due to the greater amount of active species coming from this gas. Although active N 2 gas species are predominant, active O 2 gas species can also affect ZrO2 functional groups. Thus, the pre-treatment contributes both to increasing hydrophilic character as well as promoting chemical changes in the functional groups present on the nanocomposite surfaces.

Plasma technology is a fast, cost-effective, and pollution-free method that can be used in place of conventional methods to overcome seed dormancy. The goal of the present study was to determine the effect of different application times of atmospheric plasma on soaking and germination of Hybanthus calceolaria seeds in order to accelerate these processes. Helium plasma jet produced by dielectric barrier discharge was used to treat H. calceolaria seeds with applications of 1, 5, and 10 minutes. The treated seeds were characterized considering their weight variation during soaking, changes in electrical conductivity, and pH. It was found that germination depended on the plasma application time. The treatment of H. calceolaria seeds with atmospheric plasma for 1 minute provided 3.5 times greater germination in comparison to untreated seeds. Atmospheric plasma technology obtained by dielectric barrier discharge had potential of being used as a germination accelerant in H. calceolaria seeds. The treatment of H. calceolaria seeds using atmospheric plasma for 1 minute favored germination. A tecnologia de plasma constitui-se em um método rápido, econômico e livre de poluição que pode ser utilizada na superação de dormência de sementes em substituição aos métodos convencionais. O objetivo com esse estudo foi verificar o efeito do tempo de aplicação de plasma atmosférico sobre a embebição e germinação de sementes de Hybanthus calceolaria visando à aceleração destes processos. Jato de plasma de gás hélio, produzido por descarga em barreira dielétrica (DBD), foi utilizado para tratar as sementes de H. calceolaria por 1, 5 e 10 minutos de aplicação. As sementes tratadas foram caracterizadas quanto à variação de peso durante a embebição, variações da condutividade elétrica e pH. Verificou-se que a germinação depende do tempo de aplicação do plasma. O tratamento de sementes de H. calceolaria com plasma atmosférico por 1 min. proporcionou incremento na germinação de 3,5 vezes em comparação com as não tratadas. A tecnologia de plasma atmosférico, obtido por barreira dielétrica, apresenta potencial de utilização como acelerador da germinação de sementes de H. calceolaria. O tratamento de sementes de H. calceolaria à plasma atmosférico durante 1 minuto favorece a germinação.

There is a growing quest for an ideal biomaterial that shows appropriate cellular response and is not susceptible to microbial adhesion. In this study, commercial grade II titanium was submitted to RF/DC plasma surface modification at 2.2 mbar, using gas mixtures of argon, nitrogen, and oxygen at proportions 4:1:2 and 4:1:3. The surfaces were physically and chemically characterized. In order to evaluate bacterial response, the surfaces were exposed to Staphylococcus epidermidis. Oxynitrided samples, although having a higher roughness as compared with untreated samples, exhibited lower bacterial growth. This observation is probably due to the formation of different crystalline phases of nitrides and oxides caused by plasma treatment. The surface with highest contact angle and highest surface tension showed lower bacterial adhesion. These results were confirmed by scanning electron microscopy. The role of nitrogen in reducing bacterial adhesion is clear when this material is compared with untreated titanium, on which only an oxide film is present.

Polyester fabric samples – PET (poly (ethylene terephtalate)), were treated with oxygen plasma, in order to alter the hydrophilicity of such material. The process parameters: working pressure, current, tension and temperature were kept constant, varying only the treatment time. In order to evaluate the change caused on samples hydrophilicity, as well as the influence of the treatment time, the vertical wicking test was used. The samples were stored at standard temperature and pressure conditions, and their wettability were measured one day after the treatment and repeated after 30, 60 and 360 days, in order to check the stability of the effects produced. Scanning electron microscopy (SEM), Raman and ATR (Attenuated total reflection) spectroscopies were used to evaluate physical and chemical alterations on the samples surface. The results have shown a substantial improvement on the hydrophilicity of the treated samples compared to the non-treated sample.

Apesar das inúmeras publicações a respeito da versatilidade da técnica de descarga por barreira dielétrica (DBD), principalmente em aplicações emergentes como descontaminação biológica e química, pouco se apresentou sobre a influência dos parâmetros de processos. No presente trabalho é analisada a influência dos parâmetros do processo sobre as espécies ativas do plasma formado quando ar é utilizado como atmosfera. Analisou-se a influência da distância e voltagem aplicada entre eletrodos, bem como a frequência do pulso aplicado. As análises das espécies foram realizadas diagnosticando o plasma por espectroscopia de emissão óptica (EEO). Esses resultados foram correlacionados com dados da potência consumida no processo de produção de plasma, obtidos a partir das figuras de Lissajous. O equipamento DBD utilizado possui sua máxima eficiência de produção de plasma atmosférico com a distância entre eletrodos fixada em 0,5mm Voltagem de 15 kV e frequência de 500 ou 600 Hz dependendo da espécie ativa que se queira em maior quantidade N2 357nm ou N2 337nm respectivamente .

In the present work, Al2O3/ZrO2 nanocomposite surfaces were treated with plasma under gaseous atmospheres with different proportions of N2, H2, and O2 to improve the adhesion of biomimetically deposited calcium phosphate layers. Initially, samples of Al2O3/ZrO2 were shaped and sintered at 1500 °C for 2 h. Subsequently, the surfaces were treated and coated with calcium phosphate. The treated and untreated surfaces before and after the deposition of the biomimetic coatings were characterised using scanning electron microscopy, confocal microscopy, infrared spectroscopy, X-ray diffraction, and a scratch test. The results showed that pre-treatment increased the amount of calcium phosphates formed on the surface regardless of the gas composition used owing to the increase in polarity on the treated surfaces and formation of oxygenated groups such as Al-OH and Zr-OH. The phases of calcium phosphates formed were: hydroxyapatite (HA), α-tricalcium phosphate (α-TCP), and β-tricalcium phosphate (β-TCP). Although the HA phase was predominant, the α-TCP phase was responsible for increasing the adhesion of calcium phosphates onto the surface. Among the gaseous compositions used, the combination of 30% N2, 50% H2, and 20% O2 favoured the highest formation of phosphates on the surface of the nanocomposite.

This study aimed to obtain a bifunctional fabric from the point of view of hydrophilicity/hydrophobicity for biomedical applications. To achieve this, both sides of a fabric of polylactic acid (PLA) were subjected to a plasma treatment. While in a side the oxygen was introduced to the other side, simultaneously, was added methane. The plasma treatment was performed at 100 W, 1.8 mbar, during 30 minutes. By Scanning Electron Microscopy (SEM) morphological analysis, it became evident that the fabric side facing the oxygen inlet showed micropittings, while the reverse side had smooth surfaces. Analysis by X-Ray photoelectron spectroscopy (XPS) revealed an increase in the amount of oxygen in the surface of the PLA on both sides of the fabric. The surface function was characterized by measurements of water absorption rate, where it was determined that one fabric side was more hydrophilic than the other side. The results indicated achievement of a bifunctional fabric through orientation of working gases during a plasma treatment., The authors are acknowledging to financial support supplied by CAPES - Brasília/Brazil through of the CAPES/IGC program - CGCI n° 055/2010.

Electrical discharges in liquids are currently used to synthesize nanoparticles. The plasma-liquid interaction is complex, where parameters such as electric field, ion charges and other species present are important. In order to understand the mechanism of crystallization, mother liquor (saturated solution of NaCl, MgCl2 and KCl) was used to study the effectiveness and selectivity of the crystallization caused by the application of plasma. Discharge was applied with the solution at room temperature or during cooling. X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and chemical analysis was used to evaluate the structure and composition effects on crystal structure and composition. It was observed that the discharge induces selectively crystallization, and when compared to crystals obtained conventionally by cooling, were smaller and more uniform. We therefore confirm that plasma in liquid can also be used to selectively crystallize materials in atmospheric pressure, where the sizes of the crystals must be dependent on the parameters used.

Cathodic cage discharge was developed recently in order to eliminate phenomena as edge effect and overheating, which occurs during conventional processes. In this study, the effect of cage configuration in active species during the deposition process and optical properties of TiN film were studied. TiN compound was chosen because its optical properties are very sensitive to slight variations in microstructure and film thickness, becoming a good monitoring tool in fabrication process control. Cages were made of titanium and have different holes numbers and holes diameter. Electrical efficiency of the system and optical properties of TiN films were strongly influenced by experimental conditions. It was found that with more holes at the top of cage, deposition rate and crystallinity were higher, if compared to cages with a small number of holes at the top. On the other hand, the opposite behavior was observed when more holes were located at the sidewall of cage.

High performance solar collectors are those with high selectivity surfaces, high solar radiation absorption and that do not thermally reemit to the external environment. Strategies to enhance this performance might involve surface porosity modification. In this work, a plasma treatment technique called plasma electrolytic oxidation (PEO) has been tested to produce porosity on aluminium surfaces in a controlled manner. The porosity control was made by varying the intensity, frequency and duty cycle of the applied voltage pulses. The aluminium sample was placed in a solution of 1 g/L Na2SiO3. Voltage of 500 V and current density of 0.17 A cm2 was applied between electrodes. Three duty cycles were used: 33.33%, 50.00% and 67.77%. After treatment, the size, number and distribution of pores were evaluated. These parameters were correlated with both surface reflectance and optical absorbance. It was possible to control the porosity by controlling the electrical parameters of the process. While the mean pore size was directly related to the duty cycle, the inverse occurred for the number of pores. Surface treated with duty cycle of 33.33% presented higher values of absorption for all wavelength range.

The effect of plasma applied to mulungu (Erythrina velutina) seeds was studied to verify its influence on the germination, water absorption, wettability and structure of the seeds. The plasma jet used in this study was produced by dielectric barrier discharge (DBD) in a helium gas flow of 0.03 L/s at a distance of 13 mm for 60 s. The plasma treatment significantly affected the seed germination rate, which was approximately 5% higher than that of the untreated group. Micropyle and hilum contributed a greater proportion to uptake. When sealed in the hilar or micropyle regions the amount of water absorbed into the seed decreased approximately 75% compared to the unsealed seed. This difference suggests that these two regions together act cooperatively in the water absorption. However, when plasma treated seed was blocked in the micropyle region, water absorption was higher higher than in seeds blocked hilum. This difference suggests that the plasma treatment changed the wettability of the hilum more effectively than it changed the micropyle. These results indicate that plasma can significantly change the hydrophilicity, water absorption and percentage of seed germination in E. velutina.

Nos últimos anos tem-se observado um grande crescimento em tecnologias para modificação de superfícies de implantes dentais visando reduzir o tempo de espera pela cicatrização, assim como possibilitar seu uso com sucesso em áreas de baixa densidade óssea. Dentre esses métodos de modificação, a nitretação por plasma tem apresentado ótimos resultados. No presente trabalho, estudou-se superfícies de titânio comercialmente puro (Grau II) modificadas através de dois tratamentos por plasma diferentes (nitretação planar e nitretação em cátodo oco), com o objetivo de obter uma otimização da superfície para aplicações biomédicas. Uma avaliação da composição química e um estudo da rugosidade e textura destas amostras foram realizados. Em seguida, depositou-se células-tronco sobre essas superfícies e uma comparação entre as novas propriedades obtidas e a proliferação celular foi feita. Os resultados mostraram que a nitretação por plasma produziu mudanças significativas na textura superficial das amostras de titânio. A rugosidade foi superior nas amostras nitretadas em cátodo oco. Encontrou-se diferença estatisticamente significante na proliferação celular das amostras nitretadas em cátodo oco quando comparadas com as amostras sem tratamento. Essas técnicas de modificação são, portanto, efetivas e possuem influência direta nas características da superfície e no comportamento de células-tronco.

One of the main problems in using vegetable fibers as reinforcement in aggressive cement matrix is the penetration of alkaline products in the porous structure of the filaments, making them very fragile with the time. In this sense a series of physical and chemical methods of surface modification has been used in order to improve its characteristics. The plasma surface modification technique is a physical method surface modification that utilizes ionized gas at low pressure to change the chemical nature and the substrate surface morphology of both organic and inorganic materials without changing their intrinsic properties. This is considered an environmentally friendly process without generation of contamination and has a low operating cost compared to some chemical (such as silane based) treatments. In the present study, the sisal fibers were treated with methane plasma generated by direct electric current during 10, 20 and 30 min with gas flow of 5 cm3/s and current of 0.10 A. The study presents some mechanical, physics and chemical characteristics of sisal fiber after being subjected to treatment with methane cold plasma. The results presented indicate that treatment with methane cold plasma induced changes in sisal fibers at all times of exposure to treatment (10, 20 and 30 min). However, the major changes in structural and mechanical components may be seen in fibers treated with 10 min of exposure to plasma.

This study aimed to characterize the morphology of filler particles and to analyze the effect of shortened and extended photoactivation times on hardness (VHN) and cross-link density (CLD) of resin-based low-viscosity materials.Sixteen commercially available materials were tested: four fissure sealants (Alpha Seal, Fluroshield Yellowed, Bioseal and Fluroshield White) and 12 flowable composites (Opallis T, Permaflo T, Opallis A2, Natural Flow A2, Master Flow A2, Permaflo A2, Filtek Z350 A2, Natural Flow O, Master Flow OA2, Opallis OA3.5, Filtek Z350 OA3, Opallis OP) at six curing times (10 s, 20 s, 30 s, 40 s, 50 s and 60 s). Specimens were fabricated (n = 5), analyzed by Scanning Electron Microscopy, by VHN and by CLD.Unimodal and multimodal filler particles sizes with spherical and irregular shapes were observed. Unfilled materials were also detected. There were no differences among curing times for either VHN or CLD. Opallis A2 and Opallis OA3.5 showed the highest VHN at all curing times, whereas Master Flow A2 and Master Flow OA2 presented the lowest VHN. Opallis A2 presented the highest CLD at all curing times and Alpha Seal showed the lowest CLD.Filler particle morphology differed among the resin-based low-viscosity materials tested. The shortest photoactivation time tested could yield similar VHN and CLD means to those provided by the most extended photoactivation time.

Resumen pt: Objetivo: o presente estudo teve como objetivo avaliar, atraves de experimentos in vitro utilizando cultura celular, a capacidade de adesao das celulas d...

The objective of this work is to determine the best parameters for brazing ceramic joints of pre-metallized Al2O3 with Ti by a plasma process using amorphous ribbons of Cu49Ag45Cex alloy as the addition metal. The alloys were prepared in an arc oven, and later processed by melt spinning, varying Cerium content by 4–6%. Brazing took place in a vacuum oven and the following variables were analysed: deposition time of the Ti film and temperature and brazing time, which were related to the flex resistance in three points of the brazed joint. A linear regression equation was obtained, and the interaction between these factors was verified. The metallized ceramic surfaces showed excellent uniformity and the brazed joints demonstrated very good adhesion, achieving flex resistance values of up to176.8 MPa.

Nesse trabalho, apresentamos a caracterização estrutural de regiões soldadas em aço austenítico AISI-304, que foram submetidas a processo de nitretação a plasma (20%N2 + 80%H2). Posteriormente as amostras foram hidrogenadas catodicamente. As temperaturas de nitretação foram de 400, 500 e 550°C. As regiões da solda e fora da solda hidrogenadas após a nitretação foram comparadas por DRX, microscopia ótica e microscopia eletrônica de varredura (MEV). As fases austenita-γ, martensita-α', martensita-ε, ferrita-α e os nitretos CrN, γ'-Fe4N e e-Fe2+xN foram identificados. As microestruturas de ambas as regiões e da zona termicamente ativada (ZTA) foram similares. Para 400°C, a estequiometria das fases formadas foi diferente das observadas em 500°C e 550°C. Os efeitos provocados pela hidrogenação foram mais acentuados em 550°C, com o arrancamento da camada nitretada. Structural characterization of weld and outside weld regions of AISI-304 nitrided (20%N + 80%H) and cathodically hydrogenated is presented. Nitriding temperatures were 400, 500 e 550°C. The weld and outside weld regions were compared by XRD, optical microscopy and SEM. The phases γ-austenite, α'-martensite, ε-martensita and α-ferrite and the nitrides: CrN, γ'-Fe4N e e-Fe2+xN were identified. Microstructures of both regions and the thermal active zone were similar. For 400°C the stoichiometry of the formed phases was different from that formed at 500°C and 550°C. Hydrogen effects were more intense for 550°C, due to chipping occurrence.

Este trabalho teve como objetivo determinar os melhores parâmetros para brasagem de juntas cerâmicas de Al2O3 pré-metalizadas com Ti por processo a plasma utilizando fitas amorfas de ligas Cu49Ag45Cx e como metal de adição. As ligas foram preparadas em forno a arco, e, posteriormente processadas por melt-spinning, variando conteúdo Ce de 4-6. %. A brasagem foi realizada em forno à vácuo e as seguintes variáveis analisadas: tempo de deposição do filme de Ti e temperatura e tempo de brasagem , que foram relacionados com a resistência à flexão em 3 pontos da junta brazada. A equação de regressão linear foi obtida, e verificou-se a interação entre estes fatores. As superfícies cerâmicas metalizadas apresentaram excelente uniformidade e as juntas brasadas muito boa adesão atingindo valores de resistência à flexão de até 176,8 MPa.This work had as objective to establish de best brazing parameter to joint Al2O3 pre-metalized with Ti by plasma process using amorphous ribbons of Cu49g45Ce x alloys as filler metals. The alloys were prepared in arc furnace and processed by melt-spinning process varying the Ce percentiles from 4 to 6. % . The brazing was accomplished in vacuum furnace and the following variables analyzed: deposition time of Ti film, brazing temperature and brazing times which were related to the brazed joint 3-point bending resistance. The interaction between those factors was obtained by linear regression equation. The metalized ceramic surfaces presented an good uniformity and the joint a very good adhesion reaching bending resistance up to 176,8 MPa.

Este trabalho teve como objetivo determinar os melhores parâmetros para brasagem de juntas cerâmicas de Al2O3 pré-metalizadas com Ti por processo a plasma utilizando fitas amorfas de ligas Cu49Ag45Cx e como metal de adição. As ligas foram preparadas em forno a arco, e, posteriormente processadas por melt-spinning, variando conteúdo Ce de 4-6. %. A brasagem foi realizada em forno à vácuo e as seguintes variáveis analisadas: tempo de deposição do filme de Ti e temperatura e tempo de brasagem , que foram relacionados com a resistência à flexão em 3 pontos da junta brazada. A equação de regressão linear foi obtida, e verificou-se a interação entre estes fatores. As superfícies cerâmicas metalizadas apresentaram excelente uniformidade e as juntas brasadas muito boa adesão atingindo valores de resistência à flexão de até 176,8 MPa. This work had as objective to establish de best brazing parameter to joint Al2O3 pre-metalized with Ti by plasma process using amorphous ribbons of Cu49g45Ce x alloys as filler metals. The alloys were prepared in arc furnace and processed by melt-spinning process varying the Ce percentiles from 4 to 6. % . The brazing was accomplished in vacuum furnace and the following variables analyzed: deposition time of Ti film, brazing temperature and brazing times which were related to the brazed joint 3-point bending resistance. The interaction between those factors was obtained by linear regression equation. The metalized ceramic surfaces presented an good uniformity and the joint a very good adhesion reaching bending resistance up to 176,8 MPa.

Titanium (Ti) is currently the most widely used material for the manufacture of orthopedic and dental implants. Changes in the surface of commercial pure Ti (cp Ti) can determine the functional response of cells, and is therefore a critical factor for the success of the implant. However, the genotoxicity of titanium surfaces has been poorly studied. Thus, the purpose of this study was to evaluate the genotoxic potential of a new titanium surface developed by plasma treatment using argon-ion bombardment and compare it with an untreated titanium surface. Accordingly, comet assay, analysis of chromosomal aberrations (CAs), and Cytokinesis Block Micronucleus (CBMN) assay were carried out, using CHO-K1 (Chinese hamster ovary) cells grown on both titanium surfaces. Our results show that the untreated titanium surface caused a significant increase in % tail moment, in the number of cells with CAs, tetraploidy, micronucleus frequency, and other nuclear alterations when compared with the negative control and with the plasma-treated titanium surface. This difference may be attributed to increased surface roughness and changes in titanium oxide layer thickness.