RESUMEN
In healthcare facilities, infections caused by Staphylococcus aureus (S. aureus) from textile materials are a cause for concern, and nanomaterials are one of the solutions; however, their impact on safety and biocompatibility with the human body must not be neglected. This study aimed to develop a novel multilayer coating with poly(allylamine hydrochloride) (PAH) and immobilized ZnO nanoparticles (ZnO NPs) to make efficient antibacterial and biocompatible cotton, polyester, and nylon textiles. For this purpose, the coated textiles were characterized with profilometry, contact angles, and electrokinetic analyzer measurements. The ZnO NPs on the textiles were analyzed by scanning electron microscopy and inductively coupled plasma mass spectrometry. The antibacterial tests were conducted with S. aureus and biocompatibility with immortalized human keratinocyte cells. The results demonstrated successful PAH/ZnO coating formation on the textiles, demonstrating weak hydrophobic properties. Furthermore, PAH multilayers caused complete ZnO NP immobilization on the coated textiles. All coated textiles showed strong growth inhibition (2-3-log reduction) in planktonic and adhered S. aureus cells. The bacterial viability was reduced by more than 99%. Cotton, due to its better ZnO NP adherence, demonstrated a slightly higher antibacterial performance than polyester and nylon. The coating procedure enables the binding of ZnO NPs in an amount (<30 µg cm-2) that, after complete dissolution, is significantly below the concentration causing cytotoxicity (10 µg mL-1).
RESUMEN
The green transition initiative has exposed the importance of effective recycling of Nd-Fe-B magnets for achieving sustainability and foreign independence. In this study, we considered strip-cast, hydrogenated, jet-milled Nd-Fe-B powder as a case study to explore the potential for selective chemical leaching of the Nd-rich phase, aiming to extract the Nd2Fe14B matrix phase. Diluted citric and nitric acids at concentrations of 0.01, 0.1, and 1 M were considered potential leaching mediums, and the leaching time was 15 min. Microstructural investigation, magnetic characterization, and elemental compositional analysis were performed to investigate leaching efficiency and selectivity. Based on SEM analysis, Nd/Fe ratio monitoring via ICP-MS, and the high moment/mass value at 160 emu/g for the sample leached with 1 M citric acid, 1 M citric acid proved highly selective toward the Nd-rich phase. Exposure to nitric acid resulted in a structurally damaged Nd2Fe14B matrix phase and severely diminished moment/mass value at 96.2 emu/g, thus making the nitric acid unsuitable for selective leaching. The presence of hydrogen introduced into the material via the hydrogen decrepitation process did not notably influence the leaching dynamics. The proposed leaching process based on mild organic acids is environmentally friendly and can be scaled up and adopted for reprocessing industrial scrap or end-of-life Nd-Fe-B magnets to obtain single-phase Nd-Fe-B powders that can be used for novel magnet-making.
RESUMEN
Hydraulic calcium silicate-based cements (HCSCs) have become a superior bioceramic alternative to epoxy-based root canal sealers in endodontics. A new generation of purified HCSCs formulations has emerged to address the several drawbacks of original Portland-based mineral trioxide aggregate (MTA). This study was designed to assess the physio-chemical properties of a ProRoot MTA and compare it with newly formulated RS+, a synthetic HCSC, by advanced characterisation techniques that allow for in situ analyses. Visco-elastic behaviour was monitored with rheometry, while phase transformation kinetics were followed by X-ray diffraction (XRD), attenuated total reflectance Fourier transform infrared (ATR-FTIR), and Raman spectroscopies. Scanning electron microscopy with energy-dispersive spectroscopy, SEM-EDS, and laser-diffraction analyses was performed to evaluate the compositional and morphological characteristics of both cements. While the kinetics of surface hydration of both powders, when mixed with water, were comparable, an order of magnitude finer particle size distribution of RS+ coupled with the modified biocompatible formulation proved pivotal in its ability to exert predictable viscous flow during working time, and it was more than two times faster in viscoelastic-to-elastic transition, reflecting improved handling and setting behaviour. Finally, RS+ could be completely transformed into hydration products, i.e., calcium silicate hydrate and calcium hydroxide, within 48 h, while hydration products were not yet detected by XRD in ProRoot MTA and were obviously bound to particulate surface in a thin film. Because of the favourable rheological and faster setting kinetics, synthetic, finer-grained HCSCs, such as RS+, represent a viable option as an alternative to conventional MTA-based HCSCs for endodontic treatments.
RESUMEN
The aim of this in vitro study was to evaluate the long-term stability of one-piece diameter reduced zirconia oral implants under the influence of loading and artificial aging in a chewing simulator as well as the fracture load in a static loading test. Thirty-two one-piece zirconia implants with a diameter of 3.6 mm were embedded according to the ISO 14801:2016 standard. The implants were divided into four groups of eight implants. The implants of group DLHT were dynamically loaded (DL) in a chewing simulator for 107 cycles with a load of 98 N and simultaneously hydrothermally aged (HT) using a hot water bath at 85 °C. Group DL was only subjected to dynamic loading and group HT was exclusively subjected to hydrothermal aging. Group 0 acted as a control group: no dynamical loading, no hydrothermal ageing. After exposure to the chewing simulator, the implants were statically loaded to fracture in a universal testing machine. To evaluate group differences in the fracture load and bending moments, a one-way ANOVA with Bonferroni correction for multiple testing was performed. The level of significance was set to p < 0.05. In the static loading test, group DLHT showed a mean fracture load of 511 N, group DL of 569 N, group HT of 588 N and control group 0 of 516 N. The average bending moments had the following values: DLHT: 283.5 Ncm; DL: 313.7 Ncm; HT: 324.4 Ncm; 0: 284.5 Ncm. No significant differences could be found between the groups. Hydrothermal aging and/or dynamic loading had no significant effect on the stability of the one-piece diameter reduced zirconia implants (p > 0.05). Within the limits of this investigation, it can be concluded that dynamic loading, hydrothermal aging and the combination of loading and aging did not negatively influence the fracture load of the implant system. The artificial chewing results and the fracture load values indicate that the investigated implant system seems to be able to resist physiological chewing forces also over a long service period.
RESUMEN
Avoidance goals heighten the salience of negative social experiences, and in intimate relationships such an orientation may contribute to communication difficulties and the perpetuation of avoidance. We therefore hypothesized that individuals with stronger avoidance goals would be particularly prone to engage in escalating levels of negative communication with their intimate partner, and we tested this prediction by conducting sequential analyses on videotaped observational data (28,470 observations) collected from 365 heterosexual couples engaging in a relationship-related conflict. While less avoidance-oriented spouses showed a decline in their likelihood of negative communication over the course of the 8-min conflict discussion, the likelihood that more avoidance-oriented spouses would display negative communication behaviors remained at a high level. The likelihood of negative communication even increased when avoidance-oriented spouses were confronted with negative communication behavior of their partners. The effects of avoidance orientation were independent of relationship satisfaction and neuroticism. These findings demonstrate that avoidance goals underlie individuals' heightened reactivity to the partner's negative behavior, while also clarifying 1 possible reason why some individuals engage in communication behaviors that may prove maladaptive to their relationship.
