Yunjiang Yu

This study developed a novel material based on polyvinyl alcohol–ethylene glycol (PVA-EG) hydrogel and systematically evaluated its potential application in the removal of animal glue from book surfaces. The microstructure, surface properties, and mechanical characteristics of the PVA-EG hydrogel were analyzed using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), contact angle measurements, a universal testing machine, and a dynamic mechanical analysis (DMA). The introduction of ethylene glycol (EG) could weaken hydrogen bonding interactions between PVA chains to enhance the molecular chain flexibility of the hydrogel. Notably, the 10% PVA-EG hydrogel shows better crystallinity, higher hydrophilicity, and optimal balance between mechanical strength and flexibility compared to pure PVA, which is conducive to improving the efficiency of the removal of animal glue. Additionally, the effectiveness of the process of removing animal glue was verified by real-time monitoring using europium nitrate at a concentration of 0.4% (w/v) as a fluorescent marker. Such hydrogels with high mechanical properties, strong surface hydrophilicity, good removal efficiency, and gentle treatment characteristics have potential applications in the restoration of cultural heritage.

The development of energy-efficient, sensitive, and reliable gas sensors for monitoring NO₂ concentrations has garnered considerable attention in recent years. In this manuscript, TiO₂ nanotube arrays/reduced graphene oxide nanocomposites with varying rGO contents (TiO₂ NTs/rGO) were synthesized via a two-step method for room temperature NO₂ gas detection. From SEM and TEM images, it is evident that the rGO sheets not only partially surround the TiO₂ nanotubes but also establish interconnection bridges between adjacent nanotubes, which is anticipated to enhance electron–hole separation by facilitating electron transfer. The optimized TiO₂ NTs/rGO sensor demonstrated a sensitive response of 19.1 to 1 ppm of NO₂, a 5.26-fold improvement over the undoped TiO₂ sensor. Additionally, rGO doping significantly enhanced the sensor’s response/recovery times, reducing them from 24 s/42 s to 18 s/33 s with just 1 wt.% rGO. These enhancements are attributed to the increased specific surface area, higher concentration of chemisorbed oxygen species, and the formation of p-n heterojunctions between TiO₂ and rGO within the nanocomposites. This study provides valuable insights for the development of TiO₂/graphene-based gas sensors for detecting oxidizing gases at room temperature.

The presence of harmful oxidizing gases accelerates the oxidation of cellulose fibers in paper, resulting in reduced strength and fading ink. Therefore, the development of highly sensitive NO₂ gas sensors for monitoring and protecting books holds significant practical value. In this manuscript, ZnO/MoS₂ composites were synthesized using sodium molybdate and thiourea as raw materials through a hydrothermal method. The morphology and microstructure were characterized by X-ray diffraction analysis (XRD), energy dispersive spectroscopy (EDS), field emission scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The ZnO/MoS₂ composite exhibited a flower-like structure, with ZnO nanoparticles uniformly attached to the surface of MoS₂, demonstrating advantages such as high specific surface area and good uniformity. The gas sensitivity of the ZnO/MoS₂ nanocomposites reached its peak at 260 °C, with a sensitivity value around 3.5, which represents an improvement compared to pure ZnO, while also enhancing sensitivity. The resistance of the ZnO/MoS₂ gas sensor remained relatively stable in air, exhibiting short response times during transitions between air and NO₂ environments while consistently returning to a stable state. In addition to increasing adsorption capacity and improving light utilization efficiency, the formation of hetero-junctions at the ZnO-MoS₂ interface creates an internal electric field that effectively promotes the rapid separation of photo-generated charge carriers within ZnO, thereby extending carrier lifetime.

Seamless gas cylinders for diving exhibit excellent low-temperature impact performance, lightweight characteristics, and good corrosion resistance, making them widely applicable in underwater activities. However, during use, the peeling of paint or corrosion on the surface of these cylinders poses a significant threat to their safety. In this study, environmentally friendly arc ion plating technology was used to deposit TiBN, CrAlN, and nano-multilayer coatings of CrAlN/TiBN. The surface morphology, tribological properties, and corrosion resistance of these coatings were investigated. The results indicated that both CrAlN and CrAlN/TiBN coatings possess fewer droplets, pinholes, and pits, and the cross-section of the CrAlN/TiBN coating exhibits a denser structure. The preferred orientation for TiBN was identified as TiB₂ (101), while that for CrAlN was Cr(Al)N (200), with the preferred orientation for CrAlN/TiBN being TiB₂ (101). The friction measurements revealed that the lowest coefficient was observed in the CrAlN/TiBN coating (0.489), followed by CrAlN (0.491) and then TiBN (0.642). Electrochemical tests conducted in artificial seawater demonstrated that the self-corrosion potential was highest for the CrAlN/TiBN coating, followed by CrAlN and lastly TiBN. The developed TiBN-based nano-multilayer coatings hold substantial application value in protecting seamless gas cylinders used in diving.

In this paper, the photocatalytic degradation of methyl orange solution by MnO₂/TiO₂ nanotube arrays (NTAs) with different structure was studied. Initially, bamboo-like TiO₂ NTAs with folded tube walls were synthesized using the anodic oxidation method. Subsequently, MnO₂ nanowires/TiO₂ NTAs and MnO₂ nanoparticles/TiO₂ NTAs were prepared via high-temperature and low-temperature hydrothermal methods, respectively. Photocurrent-time transient tests revealed that MnO₂ nanoparticles/TiO₂ NTAs produced by the low-temperature hydrothermal method exhibited a relatively good photocurrent response. All the deposited MnO₂/TiO₂ bamboo-like nanotube nanocomposites were tested for photocatalytic decomposition under different pH and light conditions. The results showed that MnO₂ could adsorb and degrade methyl orange in the absence of light and acidity, and the degradation degree was proportional to the concentrations of Mn. MnO₂ was stimulated to produce photogenic electrons, which migrated to the surface of the TiO₂ and extended the life of photogenic charge carriers.

Monitoring the gas composition in library environments is crucial for the preservation of ancient books. In this study, TiO₂ NTs/CNTs composites were synthesized via a hydrothermal method and utilized as nano-gas sensors for NO₂ detection. The surface morphology and element composition of the samples were characterized using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Additionally, the gas sensitivity of the prepared TiO₂ nanocomposites was evaluated at different temperatures, both with and without ultraviolet light irradiation. The results demonstrate that the synthesized TiO₂ NTs/CNTs samples exhibit a large specific surface area due to their titanium dioxide nanotubes (TiO₂ NTs) and carbon nanotubes (CNTs) composition. Moreover, these samples display excellent gas sensitivity under ultraviolet light irradiation at temperatures of 120 °C. Compared to uncomposited and non-ultraviolet light irradiated samples, the sensor response rate is significantly improved, enabling effective monitoring of NO₂ gas in library environments conducive to preserving ancient books. Overall, our findings highlight that the developed TiO₂ NTs/CNTs nano gas sensor holds great potential for monitoring and safeguarding ancient books.

This study employed arc ion plating technology to deposit CrAlN/CrN coatings on stainless steel substrates, adjusting deposition pressures ranging from 1.0 Pa to 4.0 Pa. A detailed analysis of the coatings’ microstructure, wear, and corrosion features was performed using X-ray diffraction, scanning electron microscopy, nanoindentation, tribometers, profilometers, and electrochemical workstations. The study revealed that the crystalline structure of the CrAlN/CrN coatings primarily consists of cubic crystals of AlN, (Cr, Al)N, and CrN. Diffraction peak intensity analysis revealed preferential orientation in the CrAlN coatings along the (111) and (200) crystal planes. As the pressure increased to 3.0 Pa, the content of Al elements peaked, and the columnar structure became denser; at this point, the H/E* ratio reached a maximum of 0.079, indicating excellent delamination and fracture resistance of the CrAlN/CrN coating at this pressure. Tests in artificial seawater environments showed that with the increase in nitrogen pressure, the friction coefficient gradually decreased, reaching its lowest at 3 Pa, approximately 0.19. The wear rate trend aligned with the friction coefficient, recorded at a mere 2.20 × 10⁻⁷ mm³/Nm. Electrochemical polarization curve tests revealed that at 3 Pa pressure, the CrAlN/CrN coating had a corrosion potential of −0.04 V, a polarization resistance of 9.28 × 10⁵ Ω·cm², and a very low corrosion current of 4.81 × 10⁻⁸ A/cm², demonstrating excellent corrosion resistance.

In this study, CrYN coatings were prepared using multi-arc ion plating at various substrate bias voltages (−50 V, −100 V, −150 V, and −200 V). X-ray diffractometry and scanning electron microscopy were used to characterize the composition and microstructure of the coatings. An electrochemical workstation and a ball-on-disk tribometer were used to investigate their corrosion and friction behavior. The results show that grain refinement can be achieved through the addition of yttrium (Y) and that the surfaces of coatings prepared under different bias voltages have varying smoothness and compactness. It was shown that surfaces prepared under −100 V bias voltages were relatively smooth and dense in structure, corresponding to a Y content of 2.83 at.%; CrYN coatings at −100 V were shown to have the highest corrosion potential and a low self-corrosion current, equating to superior corrosion resistance. Additionally, the friction coefficients of deposited CrYN coatings under bias voltages of −100 V were less than 0.2. Therefore, the coatings under bias voltages of −100 V had the minimum wear rate due to its structure, corrosion resistance, and friction.