Resumo Este trabalho teve como objetivo avaliar o efeito da aplicação de plasma atmosférico na inativação de fungos na superfície de sementes de Erythrina velutina e em colônias fúngicas isoladas. Dois experimentos foram realizados em delineamento inteiramente casualizado: no primeiro, o plasma foi aplicado na superfície das sementes usando gás hélio e plasma atmosférico por três, seis e nove minutos, além do controle (sementes sem tratamento), constituindo sete tratamentos com cinco repetições cada; no segundo experimento, placas de Petri contendo o inóculo de diferentes fungos foram tratadas com plasma atmosférico por três, seis e nove minutos (Air-3, Air-6 e Air-9) e comparadas com fungos não tratados em placas de Petri sem tratamento (controle), totalizando quatro tratamentos e cinco repetições cada. Descobrimos que a aplicação de plasma atmosférico nas sementes de E. velutina por nove minutos teve efeito antimicrobiano sobre os fungos Aspergillus niger, Aspergillus flavus, Fusarium sp., Brachysporium sp. e Rhizopus sp. A formação de colônias fúngicas isoladas de sementes de E. velutina também foi inibida por três minutos de exposição à aplicação de plasma atmosférico, exceto para A. niger, cuja inibição ocorreu a partir de 6 minutos de exposição à aplicação de plasma atmosférico.

Abstract 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.

The incorporation of oxygen and/or nitrogen into the titanium lattice has garnered significant attention due to the broad spectrum of intermediate properties that can be achieved between TiN and TiO2. This article delves into the investigation of surface modification of titanium through plasma-assisted thermochemical treatments employing H2-N2-O2 mixtures. The flow rate of the reducing gas (H2) remained constant at 24 sccm, while the flow rates of N2 and O2 were adjusted to yield a total flow rate of 60 sccm. Analysis using GIXRD, Raman spectroscopy, and XPS demonstrated that TiN exhibits stability exclusively in an oxygen-free atmosphere, while TiO2, in contrast, necessitates an oxygen flux equal to or exceeding 18 sccm for stability. Furthermore, it was found that the presence of nitrogen in the plasma atmosphere resulted in a greater expansion of the α-titanium lattice, although the solubility of interstitials decreased. These findings highlight the potential for a controlled approach to producing solid solutions or titanium oxynitrides.

Desalination plant and saltwork production currently produce large quantities of by-product, in the form of bitterns, which is generally regarded as waste. Up to now methods to discard this waste are unsustainable and restricted by high capital costs and non-universal application. Cold atmospheric plasma over liquids has led to various established industrial implementations, as well as promising applications, including chemical analysis, nanomaterials synthesis and plasma medicine. In this study interaction plasma – hypersaline water using cathodic or anodic polarization was investigated. Pulses of 2.3 kV, repeated at a frequency of 1 kHz, were applied to produce a pulsed corona discharge (PCD) over hypersaline water (HSW) surface. It was observed that in cathode polarization, considerable number of metallic cations can be extracted from the solution in the form of precipitate salts, while in anodic configuration, despite having a higher spectral intensity for Na (589.5 nm), it was less efficient in the salt precipitation. The findings of this study suggest that changing polarization also changes the mechanism of plasma interaction, indicating to be an interesting technique to explore selective saline water chemical extraction.

Amostras do aço inoxidável austenítico AISI 316 foram nitretadas em gaiola catódica nas mesmas condições de tratamento, pressão de 250 Pa, temperatura de 723 K mistura nitretante de 80%N2/H2 e variando apenas a duração do processo de 1 a 5 horas com o objetivo de observar o crescimento da camada nitretada. Houve formação de camada para todos os tempos de nitretação. A formação de camada para todas as durações de tratamento é confirmada através da microscopia óptica e também pela análise de microdureza. Os difratogramas de raios-X apresentaram fases semelhantes. Comprovando que é possível obter camada nitretada na técnica de nitretação em gaiola catódica mesmo para pequena duração de tratamento.

AISI 316 austenitic stainless steel samples have been nitrided by cathodic cage technique in same treatment conditions: pressure 250 Pa, temperature 500 ºC and nitriding mixtures 80%N2/H2. The variance is limited just to process duration, from 1 to 5 hours. In this work the objective is to observe the increase of nitrided layer. It has been seen that there was layer formation to all times of nitriding. They are confirmed through optical microscopy and microhardness analysis. The X-ray difratogram presents similar phases proving that is possible obtain nitrided layer using cathodic cage technique even to short during treatment.