This investigation has been developed to determine which microstructural changes on the eutectic α-Ni-Ni₃Si_{- monoclinic}, if any exist, result from the irradiation with Ni-ions. SRIM program has been used to simulate the interaction of the irradiation with both α-Ni and Ni₃Si_{- monoclinic} phases. X-ray diffraction studies of irradiated and non-irradiated regions have allowed us to establish that the ion irradiation promote the formation of the Ni₃₁Si_12-hexagonal intermetallic phase with hexagonal structure. An analysis of the irradiated region by High Resolution Transmission Electron Microscopy (HRTEM) confirmed the presence of the Ni₃₁Si_12-hexagonal intermetallic phase, establishing at the same time, its crystallographic relationship with the matrix. Evidently, radiation-induced segregation could cause significant changes in the chemical composition of concentrated alloys. This experimental discovery, in particular, is significant because the formation of the Ni₃₁Si_12-hexagonal phase under irradiation conditions had never been mentioned before. Nonetheless, the formation of the Ni₃₁Si_12-hexagonal intermetallic phase represents an advance in the field of the microstructural modification by ion beam irradiation, and as a consequence of this finding, it is possible to establish that the structural stability of the eutectic form of the α-Ni-Ni₃Si_-monoclinic phases under severe irradiation conditions, is questionable.

Dilute alloys of Ni–Si binary system have been used as base material to study microstructural changes caused by irradiation in complex alloys. However, non-dilute Ni–Si alloys, which are themselves also important for high-temperature applications, have been little studied under irradiation. In this paper, the behavior of a hypereutectic alloy, Ni22at.%Si, under severe irradiation conditions is evaluated, to determine changes induced on the surface and elucidate the possible mechanisms that promote them. As a result of irradiating this alloy with Ni ions of 3.66 MeV at 650°C and an incidence perpendicular to the surface, the presence of nanohills is detected, as well as groove patterns and craters, which formation is attributed to different sputtering mechanisms. To characterize these changes, optical, scanning electron and atomic force microscopies were used. Comparing the experimental findings with some of the most important physical models of sputtering, it was concluded that such changes to the surface microstructure strongly depend on the amount of energy deposited during irradiation and on how it is distributed in the microstructural features developed in the alloy during its manufacture. Moreover, when the radiation dose was changed to evaluate the sputtering yield as a dose function, it was detected as geometric sputtering mechanism.

PET biodegradation remains limited due to its intrinsic properties—high crystallinity, hydrophobicity, and strong chemical stability. These characteristics lead to extremely slow degradation rates and contribute to PET’s persistence in the environment. Understanding how microorganisms respond at the molecular level when exposed to such a recalcitrant polymer is therefore essential. Living organisms express genes in response to their needs during development. When microbes are under critical conditions, such as when contaminants are present, they express genes encoding specific enzymes that attack the pollutant. In this study, a fungus isolated from the infected fruit of the plant Randia monantha was identified as Aspergillus terreus. It was tested for polyethylene terephthalate (PET) degradation, and the fungus Aspergillus nidulans was evaluated due to its previously reported recombinant cutinases for PET degradation. A microplastic polyethylene terephthalate (PET-MP) particle size of <355 μm for degradation was established, and a PET weight loss of 1.62% for A. nidulans and 1.01% for A. terreus was found. Additionally, the degradation of PET was confirmed by FTIR and SEM. This study also compares the transcriptomic profiles of Aspergillus nidulans and Aspergillus terreus during cultivation with PET-MP residues, which serve as a replacement for the carbon source. We present the first evidence of chitinase overexpression during direct exposure of PET to Aspergillus fungi. Interestingly, chitinase expression was detected in the crude extracts of A. nidulans and A. terreus during culture in the presence of PET residues, which replaced the carbon source. The chitinase produced by each fungus has a similar molecular weight of approximately 44 kDa. Chitinase activity was monitored over a 14-day cultivation period; from day 2, chitinase activity was detected in both cultures and continued to increase until day 14, when the highest values reported in this work were 24.88 ± 4.17 U mg⁻¹ and 10.41 ± 0.47 U mg⁻¹ for A. nidulans and A. terreus, respectively. Finally, we proposed a pathway for PET degradation by Aspergillus fungi that involves mycelial adherence and the secretion of hydrophobins, followed by the production of intermediates and monomers via esterase hydrolysis, and ultimately, the entry of monomers to the ethylene glycol (EG) and terephthalic acid (TPA) pathways, further suggesting these Aspergillus as candidates to produce valuable compounds under these conditions, such as muconic acid, gallic acid, and vanillic acid.

As a study result of irradiation-induced damage, various mathematical models have been developed to explain the phenomenon of irradiation-induced surface sputtering, these models are currently used in technological fields as diverse as materials characterization and in thin film deposition used in the manufacture of electronic or medical components. However, the phenomenon is not fully understood due to its high complexity, this work has the goal to present experimental evidence of the changes induced in the surface of hypereutectic alloy Ni-22% at Si promoted by the nickel ion beam irradiation, the surface changes induced will be explained in terms of the Sigmund theory of surface sputtering.