Active species evolution in presence of different targets impacted by helium plasma jet at atmospheric pressure

A low-temperature plasma jet is generated by a dielectric barrier discharge poweredby a pulsed high voltage in helium flow (3 L/min) at atmospheric pressure inpresence of different targets (glass slide or ultra-pure water or a grounded metal plate)positioned perpendicular to the plasma propagation axis. Experimental electricalcharacterizations as discharge current, voltage and powerand optical ones as intensifiedcamera ICCD, Schlieren imaging and emission spectroscopy to follow specific excitedspecies have been achieved. The transition from laminar to turbulent regime wereobserved during the discharge ignition with a larger spreading of the plasma on thesurface target with lower dielectric permittivity and the generation of two dischargesduring each voltage pulse is highlighted during the propagation of the ionization wavethat has shown a variable speed along the plasma axis not depending on the target kind.The evolution of some active species (as OH, O and excited nitrogen and helium) areinvestigated using time resolved mapping of the emissions of radiative excited speciespropagating in ambient air between the plasma jet output andthe target. For a lowrelative permittivity target (glass), the volume ionization wave at its arrival on thetarget spreads on its surface thus behaving as a surface ionization wave. For thehighest relative permittivity (metal), a conductive channel appears between the targetsurface and the plasma jet during the first discharge, followed by a diffuse plasma plumefrom the target surface towards the plasma jet after the impact of the ionization waveon the target. A hybrid behavior is highlighted for the ultra-pure water which leadsto a short spreading of the ionization wave on the target surface, the formation of aconductive channel in ambient air between tube output and target and the formationof a plasma plume on the target surface.

Physiological response to the action of the agrotoxic 2,4-Dichlorophenoxiacetic acid in Saccharomyces cerevisiae

The presence of xenobiotic compounds in the environment is responsible for impacts on the ecosystem. An example is pesticides that pose risks to non-target species, such as microorganisms present in the soil and that are responsible for cycling nutrients, some can be used to measure the effects of these compounds, such as yeasts because when exposed to toxic substances begin to present changes in physiological and genetic mechanisms. Thus, this study aims to evaluate the toxicity effect of the 2,4-D pesticide on Pedra-2 (PE-2) and Fleischmann® (FLE) yeasts. 2,4-D dilutions of 2.0; 4.0 and 6.0 µg L-1 were added to a solution prepared with 20 ml of ultra-pure water and 2.0 g of sucrose where the yeasts were grown. The phenotypic profile of yeasts against the toxicity of the compound was evaluated quantitatively with cell viability. Using the methylene blue method and qualitatively with cell growth tests in Petri dishes containing 2% YPD medium and flocculation on slides with methylene blue. Yeasts showed loss of viability and the FLE strain showed greater sensitivity, the cellular growth of this yeast was also more affected and, consequently, presented higher flocculation rates. The data show that the longer exposure time and the doses and concentrations of 2,4-D interfered with the physiological response of the FLE yeast. Thus, we can suggest that this microorganism has the potential to be considered for environmental tests and analyses as a bioindicator.

Toxicity of Zinc Oxide Nanoparticles on the Embryo of Javanese Medaka (Oryzias javanicus Bleeker, 1854): A Comparative Study

(1) Background: Zinc oxide nanoparticles (ZnO NPs) are widely applied in various human products. However, they can be extremely toxic for aquatic organisms, particularly fish. This research was conducted to determine the LC50 of ZnO NPs on the embryos of Javanese medaka (Oryzias javanicus) in ultra-pure, deionized, and dechlorinated tap water; (2) Methods: The experiments were conducted in a completely randomized design (CRD) with three replicates for six treatments for acute (0.100, 0.250, 0.500, 1.00, 5.00, and 10.00 mg/L) exposures for each type of water; (3) Results: The LC50 of ZnO NPs at 96 h was determined as 0.643 mg/L in ultra-pure water, 1.333 mg/L in deionized water, and 2.370 in dechlorinated tap water. In addition to concentration-dependent toxicity, we also observed time-dependent toxicity for ZnO NPs. In addition, the sizes of ZnO NPs increased immediately after dispersion and were 1079 nm, 3209 nm, and 3652 nm in ultra-pure, deionized, and dechlorinated tap water. The highest concentration of measured Zn2+ in exposure concentrations was found in ultra-pure water, followed by deionized and dechlorinated tap water suspensions. Furthermore, Javanese medaka showed high sensitivity to acute exposure of ZnO NPs in all types of water.

Aminophosphonates in Nanofiltration and Reverse Osmosis Permeates

Aminophosphonates such as aminotris(methylenephosphonic acid) (ATMP) are common constituents of antiscalants. In nanofiltration (NF) and reverse osmosis (RO) processes, ATMP prevents inorganic scaling leading to more stable membrane performance. So far, little attention has been paid to the possible permeation of aminophosphonates through NF and RO membranes. We have investigated the permeability of these membrane types for ATMP and its potential metabolites iminodi(methylenephosphonic acid) (IDMP) and amino(methylenephosphonic acid) (AMPA) with two different NF membranes (TS40 and TS80) and one RO membrane (ACM2) and three different water compositions (ultra-pure water, synthetic tap water and local tap water). We found traces of phosphonates in all investigated permeates. The highest phosphonate rejection occurred with local tap water for all three membranes investigated. Filtration experiments with a technical antiscalant formulation containing ATMP indicated similar trends of phosphonate permeability through all three membranes. We assume that the separation mechanisms of the membranes are the results of a very complex relationship between physico-chemical properties such as Donnan exclusion, feed pH, feed ionic strength and feed concentration, as well as solute–solute interactions.

Preparation of ZnO Nanoparticles by 1064/532nm Laser Ablation and Studying the Effect of the Ablation Wavelength

We prepared Zinc oxide nanomaterial employing PLA (pulsed laser ablation) technique. A pure Zn target was immersed in ultra-pure water (UPW) and it was subjected to several pulses (1st. and 2nd. harmonic) of the pumping Nd: YAG laser. The influence of changing laser’s wavelength (1064, 532) nm on the characterization of the produced nanoparticles was studied. The results obtained from studying the structure, topography, and morphology of the product showed that the particles have a hexagonal shape. Also, changing the wavelength of the laser from 532nm to 1064nm leads to size reduction and density increasing of the nanoparticles.

Experimentally measured methane hydrate phase equilibria and ionic liquids inhibition performance in Qatar’s seawater

Qatar has the third-largest natural gas reserves in the world and is the second largest Liquefied natural gas (LNG) exporter in the world. These reserves are mainly located in its offshore North Field where the gas is extracted, transported to the onshore units, and is converted to LNG for international export. The formation of natural gas hydrates in the offshore subsea lines can cause unwanted blockages and hinder the smooth supply of gas supply from offshore to onshore units. In the present work, the formation and dissociation of methane gas hydrates have been studied in the ultra pure water system (UPW), artificial seawater (ASW), and Qatar seawater (QSW) at different conditions (4–10 MPa) using standard rocking cell rig. The naturally occurring seawater was collected from Ras Laffan seacoast located in Doha, Qatar. The seawater sample was examined for elemental analysis (SO4, Cl, Na, Ca, Mg, K, and Fe) using inductively coupled plasma atomic emission spectroscopy (ICP-AES) technique and its other properties like density, electrical conductivity, and pH were also measured. The experimental results show that the CH4 pure water HLVE curve is suppressed by about 3 K in Qatar seawater and 2 K in artificial seawater. The hydrate inhibition strength of the Ionic liquids (ILs) salts 3-Ethyl-1-methyl-1H-imidazol-3-ium methane-sulfonate [C7H14N2O3S] and 3-Ethyl-1-methyl-1H-imidazol-3-ium dicyanoazanide [C8H11N5] was evaluated in both the ultra pure water and Qatar seawater systems. Their performance was compared with methanol and other ILs salts reported in the literature. The selected ILs exhibited poor hydrate inhibition effect in the ultra pure water systems, but they show a noticeable thermodynamic and kinetic hydrate inhibition effect in the Qatar seawater system. The computational 3D molecular models of ILs and methanol were generated to cognize the plausible hydrate inhibition mechanism in the presence of these inhibitors.