Yadira Itzel Vega-Cantu

This study explores the use of biomass-based carbon aerogels from raspberry pulp as electrocatalyst for the hydrogen evolution reaction (HER). Producing hydrogen via alkaline water electrolysis, from renewable energy sources, is an attractive way to mitigate climate change, however it still presents challenges in achieving high efficiency without resorting to expensive noble metal catalysts. HER electrocatalysts obtained from metal-doped biomass present a promising alternative for cost efficient, durable and renewable materials. Freeze dried raspberry pulp with added iron salts was pyrolyzed, resulting in carbon aerogels containing iron oxide nanoparticles. These nanoparticles were later used to grow carbon nanotubes (CNT) by chemical vapor deposition which enhanced HER activity reaching an overpotential of only 408 mV at a current density of -10 mA cm^-2, an increase in performance by 30% when compared to aerogels without CNTs. This shows that our synthetic approach is effective for catalysis applications, and its versatility means that efficiency could be improved further by tuning the properties of iron oxide nanoparticles and the three-dimensional interconnected porous network of the carbon aerogel.

Universities should prioritize equipping students with the ability to tackle real-world challenges during their professional training. This project aimed to inspire senior Nanotechnology Engineering students to develop creative solutions by using a problem-based learning approach. The focus of this project was to assess the use of Fullerenes (C60) in commercial cosmetic formulations, and to verify their efficacy in achieving the advertised effects. Nowadays, there is an increasing number of skin care cosmetics that claim to contain fullerenes (𝑪𝟔𝟎) as antioxidant agents [1]. The properties of these products have been evaluated using human fibroblast and keratinocyte cell lines. However, there are no studies evaluating their antioxidant properties in vitro when incorporated into a cosmetic formulation. The present work evaluates the antioxidant capacity of fullerenes (𝑪𝟔𝟎) in a cosmetic base formulation in a dermal fibroblast (HDFa) cell line. To modify its highly hydrophobic character, fullerenol C60 (OH)n ⋅ mH2O was synthesised from pure 𝑪𝟔𝟎 and incorporated into a cosmetic formulation as an active ingredient at concentrations of 0. 2 and 0.5 % w/w. Preliminary results show that the cell viability of HDFa fibroblasts was not affected by treatments at concentrations of 0.1 and 0.5 mg/ml. With reference to its antioxidant properties, the DPPH inhibition test showed that there were no significant effects when fullerenol was incorporated into the cosmetic base formulation as an active ingredient at concentrations of 31.25, 62.5 and 125 µg/ml. However, in the cellular antioxidant capacity test, a tendency to reduce the production of reactive oxygen species was observed when fullerenol was incorporated as an active in the base formulation at both 0.2% and 0.5%, demonstrating its antioxidant potential.

Glass ionomer cements and resin-based composites are promising materials in restorative dentistry. However, their limited mechanical properties and the risk of bulk/marginal fracture compromise their lifespan. Intensive research has been conducted to understand and develop new materials that can mimic the functional behavior of the oral cavity. Nanotechnological approaches have emerged to treat oral infections and become a part of scaffolds for tissue regeneration. Carbon nanotubes are promising materials to create multifunctional platforms for dental applications. This review provides a comprehensive survey of and information on the status of this state-of-the-art technology and describes the development of glass ionomers reinforced with carbon nanotubes possessing improved mechanical properties. The applications of carbon nanotubes in drug delivery and tissue engineering for healing infections and lesions of the oral cavity are also described. The review concludes with a summary of the current status and presents a vision of future applications of carbon nanotubes in the practice of dentistry.

In this work, we present the results of two synthesis approaches for mesoporous magnesium carbonates, that result in mineralization of carbon dioxide, producing carbonate materials without the use of cosolvents, which makes them more environmentally friendly. In one of our synthesis methods, we found that we could obtain nonequilibrium crystal structures, with acicular crystals branching bidirectionally from a denser core. Both Raman spectroscopy and X-ray diffraction showed these crystals to be a mixture of sulfate and hydrated carbonates. We attribute the nonequilibrium morphology to coprecipitation of two salts and short synthesis time (25 min). Other aqueous synthesis conditions produced mixtures of carbonates with different morphologies, which changed depending on drying temperature (40 or 100 °C). In addition to aqueous solution, we used supercritical carbon dioxide for synthesis, producing a hydrated magnesium carbonate, with a nesquehonite structure, according to X-ray diffraction. This second material has smaller pores (1.01 nm) and high surface area. Due to their high surface area, these materials could be used for adsorbents and capillary transport, in addition to their potential use for carbon capture and sequestration.

Carbon nanoribbons can be produced by exfoliation or unzipping of multiwalled carbon nanotubes using strong oxidants and acids or via metal intercalation-exfoliation in liquid ammonia followed by acid and thermal exfoliation. These unzipping methods tend to produce ribbons of several layers, and it may be difficult to separate individual, monolayer graphene nanoribbons. This work

The use of hybrid manufacturing to produce bimodal scaffolds has represented a great advancement in tissue engineering. These scaffolds provide a favorable environment in which cells can adhere and produce new tissue. However, there are several areas of opportunity to manufacture structures that provide enough strength and rigidity, while also improving chemical integrity. As an advancement in the manufacturing process of scaffolds, a cooling system was introduced in a fused deposition modeling (FDM) machine to vary the temperature on the printing bed. Two groups of polylactic acid (PLA) scaffolds were then printed at two different bed temperatures. The rate of degradation was evaluated during eight weeks in Hank’s Balanced Salt Solution (HBSS) in a controlled environment (37 °C–120 rpm) to assess crystallinity. Results showed the influence of the cooling system on the degradation rate of printed scaffolds after the immersion period. This phenomenon was attributable to the mechanism associated with alkaline hydrolysis, where a higher degree of crystallinity obtained in one group induced greater rates of mass loss. The overall crystallinity was observed, through differential scanning calorimetry (DSC), thermo gravimetric analysis (TGA), and Fourier transformed infrared spectroscopy (FTIR) analysis, to increase with time because of the erosion of some amorphous parts after immersion.