Exploring Non-Thermal Plasma and UV Radiation as Biofilm Control Strategies against Foodborne Filamentous Fungal Contaminants.

In recent years, non-thermal plasma (NTP) has emerged as a promising tool for decontamination and disinfection within the food industry. Given the increasing resistance of microbial biofilms to conventional disinfectants and their adverse environmental effects, this method has significant potential for eliminating biofilm formation or mitigating the metabolic activity of grown biofilms. A comparative study was conducted evaluating the efficacy of UV radiation and NTP in eradicating mature biofilms of four common foodborne filamentous fungal contaminants: Alternaria alternata, Aspergillus niger, Fusarium culmorum, and Fusarium graminearum. The findings reveal that while UV radiation exhibits variable efficacy depending on the duration of exposure and fungal species, NTP induces substantial morphological alterations in biofilms, disrupting hyphae, and reducing extracellular polymeric substance production, particularly in A. alternata and F. culmorum. Notably, scanning electron microscopy analysis demonstrates significant disruption of the hyphae in NTP-treated biofilms, indicating its ability to penetrate the biofilm matrix, which is a promising outcome for biofilm eradication strategies. The use of NTP could offer a more environmentally friendly and potentially more effective alternative to traditional disinfection methods.

Antibiofilm activity of silver nanoparticles biosynthesized using viticultural waste.

Green methods have become vital for sustainable development of the scientific and commercial sphere; however, they can bring new challenges, including the need for detailed characterization and elucidation of efficacy of their products. In this study, green method of silver nanoparticles (AgNPs) production was employed using an extract from grapevine canes. The aim of the study was to contribute to the knowledge about biosynthesized AgNPs by focusing on elucidation of their antifungal efficiency based on their size and/or hypothesized synergy with bioactive substances from Vitis vinifera cane extract. The antifungal activity of AgNPs capped and stabilized with bioactive compounds was tested against the opportunistic pathogenic yeast Candida albicans. Two dispersions of nanoparticles with different morphology (characterized by SEM-in-STEM, DLS, UV-Vis, XRD, and AAS) were prepared by modification of reaction conditions suitable for economical production and their long-term stability monitored for six months was confirmed. The aims of the study included the comparison of the antifungal effect against suspension cells and biofilm of small monodisperse AgNPs with narrow size distribution and large polydisperse AgNPs. The hypothesis of synergistic interaction of biologically active molecules from V. vinifera extracts and AgNPs against both cell forms were tested. The interactions of all AgNPs dispersions with the cell surface and changes in cell morphology were imaged using SEM. All variants of AgNPs dispersions were found to be active against suspension and biofilm cells of C. albicans; nevertheless, surprisingly, larger polydisperse AgNPs were found to be more effective. Synergistic action of nanoparticles with biologically active extract compounds was proven for biofilm cells (MBIC80 20 mg/L of polydisperse AgNPs in extract), while isolated nanoparticles suspended in water were more active against suspension cells (MIC 20 mg/L of polydisperse AgNPs dispersed in water). Our results bring new insight into the economical production of AgNPs with defined characteristics, which were proven to target a specific mode of growth of significant pathogen C. albicans.

Interface-Driven Strain in Heavy Ion-Irradiated Zr/Nb Nanoscale Metallic Multilayers: Validation of Distortion Modeling via Local Strain Mapping.

Nanolayered metallic alloys are promising materials for nuclear applications thanks to their resistance to radiation damage. Here, we investigate the effect of ion (C, Si, and Cu) irradiation at room temperature with different fluences into sputtered Zr/Nb metallic multilayer films with periods 27 nm (thin) and 96 nm (thick). After irradiation, while a high strain in the entire thin nanoscale metallic multilayer (NMM) is observed, a quite small strain in the entire thick NMM is established. This difference is further analyzed by a semianalytical model, and the reasons behind it are revealed, which are also validated by local strain mapping. Both methods show that within a thick layer, two opposite distortions occur, making the overall strain small, whereas in a thin layer, all the atomic planes are affected by the interface and are subjected to only a single type of distortion (Nb─tension and Zr─compression). In both thin and thick NMMs, with increasing damage, the strain around the interface increases, resulting in a release of the elastic energy at the interface (decrease in the lattice mismatch), and the radiation-induced transition of the Zr/Nb interfaces from incoherent to partially coherent occurs. Density functional theory simulations decipher that the inequality of point defect diffusion flux from the inner to the interface-affected region is responsible for the presence of opposite distortions within a layer. Technologically, based on this work, we estimated that Zr/Nb55 with thicknesses around Zr = 24 nm and Nb = 31 nm is the most promising multilayer system with the high radiation damage resistance and minimum swelling for nuclear applications.

Microstructural Investigation of LME Crack Initiated in Ferritic/Martensitic Steel T91 Loaded in Liquid Lead-Bismuth Eutectic at 300 °C.

Liquid lead-bismuth eutectic (LBE) is one of the candidate materials for advanced nuclear systems. The structural materials used in contact with LBE are selected according to the resistance to liquid metal corrosion, irradiation embrittlement, and compatibility with the coolant. However, simultaneous presence of mechanical strain and LBE environment can induce liquid metal embrittlement (LME) in these materials. In this study, a specimen from candidate ferritic-martensitic steel T91 was tested by Constant Extension Rate Tensile (CERT) test exposed to PbBi environment with oxygen concentration 6 × 10-6 wt % at 300 °C up to rupture. Post-test examination using scanning electron microscopy (SEM) showed a deep crack indicating features of LME in the plastic strained region of the tested specimen. Further investigations focused on characterization of the fracture path and microstructure determination using focused ion beam (FIB) and energy dispersive X-ray spectrometry/electron backscatter diffraction (EDX/EBSD). This observation revealed that the dominant LME failure mode of the observed crack is translath or transgranular and the crack stopped at the high-angle grain boundary. The role of oxides in the crack initiation is discussed.

Nanocrystalline Boron-Doped Diamond as a Corrosion-Resistant Anode for Water Oxidation via Si Photoelectrodes.

Due to its high sensitivity to corrosion, the use of Si in direct photoelectrochemical (PEC) water-splitting systems that convert solar energy into chemical fuels has been greatly limited. Therefore, the development of low-cost materials resistant to corrosion under oxidizing conditions is an important goal toward a suitable protection of otherwise unstable semiconductors used in PEC cells. Here, we report on the development of a protective coating based on thin and electrically conductive nanocrystalline boron-doped diamond (BDD) layers. We found that  BDD layers protect the underlying Si photoelectrodes over a wide pH range (1-14) in aqueous electrolyte solutions. A BDD layer maintains an efficient charge carrier transfer from the underlying silicon to the electrolyte solution. Si|BDD photoelectrodes show no sign of performance degradation after a continuous PEC treatment in neutral, acidic, and basic electrolytes. The deposition of a cobalt phosphate (CoPi) oxygen evolution catalyst onto the BDD layer significantly reduces the overpotential for water oxidation, demonstrating the ability of  BDD layers to substitute the transparent conductive oxide coatings, such as indium tin oxide (ITO) and fluorine-doped tin oxide (FTO), frequently used as protective layers in Si photoelectrodes.

Nanocrystalline diamond protects Zr cladding surface against oxygen and hydrogen uptake: Nuclear fuel durability enhancement.

In this work, we demonstrate and describe an effective method of protecting zirconium fuel cladding against oxygen and hydrogen uptake at both accident and working temperatures in water-cooled nuclear reactor environments. Zr alloy samples were coated with nanocrystalline diamond (NCD) layers of different thicknesses, grown in a microwave plasma chemical vapor deposition apparatus. In addition to showing that such an NCD layer prevents the Zr alloy from directly interacting with water, we show that carbon released from the NCD film enters the underlying Zr material and changes its properties, such that uptake of oxygen and hydrogen is significantly decreased. After 100-170 days of exposure to hot water at 360 °C, the oxidation of the NCD-coated Zr plates was typically decreased by 40%. Protective NCD layers may prolong the lifetime of nuclear cladding and consequently enhance nuclear fuel burnup. NCD may also serve as a passive element for nuclear safety. NCD-coated ZIRLO claddings have been selected as a candidate for Accident Tolerant Fuel in commercially operated reactors in 2020.

Oxygen-containing diatomic dications in the gas phase.

A variety of oxygen-containing diatomic dications XO(2+) can be produced in the gas phase by prolonged high-current (16)O(-) ion surface bombardment (oxygen ion beam sputtering) of a wide range of sample materials. These gas-phase species were detected by mass spectrometry at half-integer m/z values for ion flight times of the order of ~10-5 s. Examples provided here include ion mass spectra of AsO(2+), GaO(2+), SbO(2+), AgO(2+), CrO(2+) and BeO(2+). A detailed theoretical study of the diatomic dication system BeO(2+) is also presented.

Formation of doubly positively charged diatomic ions of Mo2(2+) produced by Ar+ sputtering of an Mo metal surface.

Long-lived metastable doubly positively charged diatomic ions of Mo2(2+) have been produced by Ar+ bombardment of a molybdenum metal surface. These exotic molecular dications, such as for example 92,95Mo2(2+) at m/z 93.5, could be observed in positive ion mass spectra for ion flight times of approximately 17 micros in a Cameca IMS-3f secondary ion mass spectrometer, when the ion extraction field was adjusted for detection of ions that are formed in the gas phase several micrometers in front of the sputtered surface. Mo2(2+) was observed at high primary current densities for projectile ions of Ar+, but could not be detected under very similar bombarding conditions for projectile ions of Xe+. Such a dependence of ion production by inert gas sputtering on the primary ion species [ionization energies: IP1(Ar) = 15.76 eV and IP1(Xe) = 12.13 eV] is unusual. It is shown that formation of Mo2(2+) dications takes place by resonant charge transfer in grazing gas-phase collisions between incoming projectile ions of Ar+ and sputtered molecular ions of Mo2+. The efficiency for such a resonant electron capture (Mo2+ + Ar+ --> Mo2(2+) + Ar) is of the order of 10(-5) for the bombarding conditions in our mass spectrometer and corresponds to a cross section of a few 10(-15) cm2.