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Carbon dots (C-dots) represent an emerging class of nontoxic nanoemitters that show excitation wavelength-dependent photoluminescence (PL) with high quantum yield (QY) and minimal photobleaching. The vast majority of studies focus on C-dots that exhibit the strongest PL emissions in the blue/green region of the spectrum, while longer wavelength emissions are ideal for applications such as bioimaging, photothermal and photodynamic therapy and light-emitting diodes. Effective strategies to modulate the PL emission of C-dot-based systems towards the red end of the spectrum rely on extensive conjugation of sp2 domains, heteroatom doping, solvatochromism, surface functionalization and passivation. Those approaches are systematically presented in this review, while emphasis is given on important applications of red-emissive suspensions, nanopowders and polymer nanocomposites.

Substantial efforts are directed into exploring the structure-properties relationships of photoluminescent Carbon dots (C-dots). This study unravels a resculpting mechanism in C-dots that is triggered by electrochemical etching and proceeds via extensive surface oxidation and carbon–carbon breakage. The process results in the gradual shrinkage of the nanoparticles and can enhance the quantum yield by more than half order of magnitude compared to the untreated analogues.

This paper presents a simple, post-synthesis treatment of carbon dots (C-dots) that relies on the oxidizing activity of sodium hypochlorite to induce surface oxidation, etching and pronounced structural rearrangements. The thus treated C-dots (ox-C-dots) exhibit up to six-fold enhancement in quantum yield compared to non-oxidised analogues, while maintaining low levels of cytotoxicity against HeLa and U87 cell lines. In addition, we demonstrate that a range of polymeric materials (polyurethane sponge, polyvinylidene fluoride membrane, polyester fabric) impregnated with ox-C-dots show advanced antifungal properties against Talaromyces pinophilus, while their untreated counterparts fail to do so.

ABSTRACT The study focuses on the preparation of electrostatically assembled layer‐by‐layer waterborne nanocoatings comprising negatively charged Nafion and positively charged imidazole modified‐graphene quantum dots (GQD‐Ims). We demonstrate here that Nafion/GQD‐Im nanocoatings can combat the growth of representative Gram‐positive and Gram‐negative bacteria, and their excellent antibacterial performance is preserved after prolonged thermal treatment, indicating that the coatings can withstand dry heat sterilization without any decline in their properties. At the same time, the coatings show remarkable chemical and structural stability, while offering protection against UV‐radiation as manifested by dye decomposition experiments. This novel type of nanocoatings demonstrates a unique combination of highly desirable characteristics, making them ideal candidates for applications related to active packaging for cosmetics and drugs, food processing, and disinfection of medical devices. Electrostatically assembled layer‐by‐layer waterborne nanocoatings comprising negatively charged Nafion and positively charged imidazole modified‐graphene quantum dots can inhibit the growth of bacteria and can withstand dry heat sterilization without any decline in their activity. In addition, the coatings show remarkable chemical and structural stability, while offering protection against UV‐radiation.

In the current work, a novel complex concentrated aluminum alloy is designed and studied. In order to investigate the unknown region of the multicomponent phase diagrams, thermo-physical parameters and the CALPHAD method were used to understand the phase formation of the Al58Mg18Zn12Cu5Si7 at.% (Al47.4Mg13.3Zn23.8Cu9.6Si6wt.%) alloy with a low-density of 2.63 g/cm3. The CALPHAD methodology showed good agreement with both the investigated microstructure and the thermodynamic parameters. The designed alloy was manufactured using an induction furnace and pour mold casting process. This study avoids the use of expensive, dangerous or scarce alloying elements and focuses instead on the utilization of widely available relatively cheaper elements. The microstructural evolution as a function of the heat-treatment was studied by means of different microstructural characterization techniques. The hardness, compressive strength and electrical conductivity of the as-cast and heat-treated alloy at room temperature were studied and correlated with the previously characterized microstructure. The alloy is characterized by a multiphase microstructure with major α-Al matrix reinforced with various secondary phases. In terms of mechanical properties, the developed alloy exhibited a high hardness value of 249 Vickers and compressive strength of 588 MPa. The present work provides a valuable insight for researchers, who aim to design and produce industry-like Aluminum based complex concentrated alloys (CCAs).

Three lightweight aluminum-based complex concentrated alloys with chemical compositions that have not been previously studied were manufactured and studied: Al52Mg9.6Zn16Cu15.5Si6.9 w.t.% or Al63Mg13Zn8Cu8Si8 a.t.% (alloy A), Al44Mg18Zn19Cu19 w.t.% or Al55Mg25Zn10Cu10 a.t.% (alloy B), and Al47Mg21.4Zn12Cu9.7Si9.7 w.t.% or Al52.7Mg26.6Zn5.6Cu4.6Si10.4 a.t.% (alloy AM), with low densities of 3.15 g/cm3, 3.18 g/cm3 and 2.73 g/cm3, respectively. During alloy design, the CALPHAD method was used to calculate a variety of phase diagrams for the various chemical compositions and to predict possible phases that may form in the alloy. The CALPHAD methodology results showed good agreement with the experimental results. The potential of the designed alloys to be used in some industrial applications was examined by manufacturing them using standard industrial techniques, something that is a rarity in this field. The alloys were produced using an induction furnace and pour mold casting process, while industrial-grade raw materials were utilized. Heat treatments with different soaking times were performed in order to evaluate the possibility of improving the mechanical properties of the alloys. Alloys A and AM were characterized by a multiphase microstructure with a dendritic FCC-Al matrix phase and various secondary phases (Q-AlCuMgSi, Al2Cu and Mg2Si), while alloy B consisted of a parent phase T-Mg32(Al,Zn)49 and the secondary phases α-Al and Mg2Si. The microstructure of the cast alloys did not appear to be affected by the heat treatments compared to the corresponding as-cast specimens. However, alterations were observed in terms of the elemental composition of the phases in alloy A. In order to investigate and evaluate the mechanical properties of the as-cast and heat-treated alloys, hardness testing along with electrical conductivity measurements were conducted at room temperature. Among the as-cast samples, alloy AM had the highest hardness (246 HV4), while among the heat-treated ones, alloy A showed the highest value (256 HV4). The electrical conductivity of all the alloys increased after the heat treatment, with the highest increase occurring during the first 4 h of the heat treatment.

This study aims to develop a comprehensive process to evaluate the leaching behavior of 3D-printed nanocomposite samples as candidate materials for potential use in wearable devices. The study involves the immersion of the 3D-printed test coupons, produced via Fused Filament Fabrication (FFF), into artificial sweat and deionized water in a controlled environment provided by a dissolution apparatus. Three distinct nanocomposite filaments were used, each consisting of different polymer matrices: thermoplastic polyurethane (TPU), copolyester (TX1501), and polyamide (PA12). The additives incorporated within these filaments encompassed silver nanoparticles (AgNPs), chopped carbon fibers (CCFs), and super paramagnetic iron oxide nanoparticles (SPIONs), respectively. The current study aims to identify potential risks associated with the release of nanomaterials and additives, through SEM/EDX analysis and in vitro measurements of proinflammatory cytokines. Furthermore, this research contributes to the advancement of safe and reliable 3D-printed materials for wearable technologies, fostering their widespread adoption in various applications.