Nanomaterials

Reduced graphene oxide (rGO) has attracted interest as a potential, cost-effective alternative to graphene layers produced by single-crystal thin-film growth techniques. Its solubility in various solvents, the ability to tune its optical and electrical properties, the ability to manipulate the optoelectronic properties of rGO-based heterojunctions, and the possibility of depositing it on flexible substrates broaden its potential applications, from electro-optical communications to environmental monitoring. In this work, we present a characterization of reduced graphene oxide (rGO) deposited on p-type Si₃N₄/Si substrate using different techniques such as Raman spectroscopy, optical transmittance, and current-voltage measurements under dark and illuminated conditions in the 400–700 nm range. Furthermore, the temperature dependence of the photocurrent of the rGO-based photoconductive device was studied in the temperature range from 300 K to 77 K. It has been shown that the electron transport mechanism through the p-type rGO/SiN/Si heterojunction at low voltage involves mainly a hopping process at 77 K and a thermionic mechanism at room temperature. Furthermore, the Fowler–Nordheim tunneling and trap-limiting mechanisms allow the presence of charge carriers in the device at both temperatures. Estimation of the main figures of merit, responsivity, detectivity, and NEP, shows an improvement in photodetection performance at low temperatures.

Acidity is a primary factor leading to the deterioration of paper-based cultural heritage, and deacidification treatment is a crucial preventive conservation measure for extending their lifespan. Traditional deacidification techniques, such as the particle suspension method and vapor phase method, have limitations in terms of penetration uniformity, treatment efficacy, or safety. Nanoscale alkaline materials, represented by nano-calcium hydroxide and nano-magnesium hydroxide, offer an innovative solution with the potential to achieve more uniform, efficient, and long-lasting paper deacidification, owing to their high specific surface area, enhanced reactivity, and superior penetration capacity derived from the nanoscale dimension. It is important to note that the realized uniformity and depth of treatment are contingent upon substrate properties (e.g., fiber density, porosity) and application parameters. This paper provides a systematic review of the main types of nanomaterials applied in the deacidification of paper artifacts—including their synthesis and dispersion stabilization methods—application techniques (such as immersion and spraying) and performance evaluation systems (including pH value, alkaline reserve, and mechanical properties). Through comparative analysis and case studies, the advantages and current challenges of nano-deacidification technology are elaborated. Finally, future directions for nano-deacidification technology are discussed, particularly focusing on material optimization, standardized evaluation, and prospects for scalable application tailored to the practical needs of cultural heritage conservation.

Despite growing concerns about the ecological and health risks of nanoplastics at environmentally relevant concentrations (ERCs), the effects of polyurethane nanoplastics (PU NPs) on environmental organisms remain unclear. This study assessed the toxicity of PU NPs in the μg/L range in Caenorhabditis elegans (C. elegans) through chronic exposure. Our results showed that 10 μg/L PU NP exposure significantly reduced brood size, head thrashes, and body bends, while 100 μg/L PU NP exposure decreased lifespan, and 1000 μg/L PU NP exposure increased mortality in wild-type C. elegans. Analysis of oxidative stress showed that both 10 and 1000 μg/L PU NP exposures elevated reactive oxygen species (ROS), SKN-1::GFP, and GST-4::GFP levels. Notably, while ROS production rose at 1000 μg/L, SKN-1::GFP and GST-4::GFP expression decreased compared to the 10 μg/L group, suggesting a compensatory response in C. elegans at lower exposure levels. The expression of oxidative stress-related genes and phenotype of differentially expressed genes indicated that C. elegans was in a compensatory phase when exposed to 10 μg/L of PU NPs, participating in the protective response of C. elegans to PU NPs. However, when exposed to 1000 μg/L of PU NPs, C. elegans was in a decompensatory phase, participating in the toxic regulation of PU NPs. In addition, under 10 μg/L PU NP exposure, cinnamon essential oil (CIEO) can enhance the expression of more antioxidant enzymes, thereby increasing the protective effect. Under 1000 μg/L PU NP exposure, CIEO could alleviate the toxic response of C. elegans to PU NPs exposure by promoting the expression of skn-1. Molecular docking analysis showed that the main active component of CIEO, cinnamaldehyde (CID), has a strong affinity with SKN-1/Nrf2. Our study is the first to emphasize the toxic effects of PU NPs on environmental organisms at ERCs and that CIEO might serve as a potential antidote for nanoplastic poisoning.