DSpace Collection:https://hdl.handle.net/10171/167482024-03-29T13:59:38Z2024-03-29T13:59:38ZLipid and polymeric nanocapsuleshttps://hdl.handle.net/10171/643442022-10-15T01:04:40Z2022-01-01T00:00:00ZTitle: Lipid and polymeric nanocapsules
Abstract: In recent years, innovative drug nanocarriers have been developed to enhance stability, bioavailability, and provide sustained release. In this chapter, systems based on natural macromolecules, lipids, or polymeric/polyelectrolyte nanocapsules and their principal chemical and functional characteristics are described. Nano-vesicular systems are especially relevant in different fields. Particularly, a promising potential is offered by systems based on colloidal nanocapsules, that exhibit a typical core-shell structure in which the drug can be confined into the cavity or in the polymeric coating that surrounds it. Both the cavity and the active substance can be lipophilic or hydrophilic and in solid or liquid form depending on the materials and methods used, making these nanocapsules attractive carriers for drug delivery. In addition, a compilation of different methods and materials employed in the preparation of these nanosystems and a recent review of applications of lipid and polymeric nanocapsules have been made, focussing on the encapsulation of drugs.2022-01-01T00:00:00ZDesign of repair air lime mortars combining nanosilica and different superplasticizershttps://hdl.handle.net/10171/430112022-02-18T13:05:00Z2016-01-01T00:00:00ZTitle: Design of repair air lime mortars combining nanosilica and different superplasticizers
Abstract: This contribution dealt with the design of different air lime mortars and pastes by combining a nanostructured pozzolanic additive, nanosilica, and different dispersing agents, superplasticizers (two different polycarboxylate ethers (PCE), a polynaphthalene sulfonate-based polymer (PNS) and a lignosulfonate (LS)). In pure air lime systems, the highest effectiveness was shown by the PCE1, whereas the PNS was the less effective superplasticizer. In samples with nanosilica, the PCE1 was also the most effective superplasticizer. LS was seen to be effective at low dosages. In the presence of the pozzolanic additive, there was a high consumption of polycarboxylates. Nanosilica provided no “active” adsorption sites, resulting in a slight decrease of the zeta potential values. PCE1 showed low adsorbed amounts, better dispersing action and required lower dosage of plasticizing agent. There was a positive combination between lime mortars with nanosilica and polycarboxylates, which resulted in a mechanical strength improvement. Also the combined presence of nanosilica, for example, with PNS or with LS yielded better compressive strengths, being LS more effective than PNS: SEM images showed the better formation of C-S-H phases in LS-mortars.2016-01-01T00:00:00ZObtaining of self-cleaning repair air lime mortars with photocatalystshttps://hdl.handle.net/10171/430102022-02-18T13:04:58Z2016-01-01T00:00:00ZTitle: Obtaining of self-cleaning repair air lime mortars with photocatalysts
Abstract: The obtaining of self-cleaning mortars is very interesting to apply them in Built Heritage. Atmospheric pollutants, mainly carbonaceous particles and gases like NOx and SO2 can lead to severe aesthetic and functional damages in artworks. In the case of mortars and renders, the use of photocatalysts -usually based on TiO2- can be worthy of consideration. Photocatalysts, after being activated by light, are able to oxidize pollutants avoiding their deposition onto building materials. In this work, different air lime mortars modified upon the addition of TiO2-based photocatalysts were obtained and studied. Photocatalysts can be incorporated in bulk and the changes in fresh state properties were studied as well as the effect of the presence of the photocatalysts on the pore structure and mechanical resistance. Finally, the photocatalytic efficiency of these materials was carried out by means of a NOx abatement test. Results showed that the presence of the photocatalysts had a positive impact on the preservation of the lime mortars characteristics.2016-01-01T00:00:00ZThe use of a lignosulfonate superplasticizer in repair air lime-metakaolin mortarshttps://hdl.handle.net/10171/430062022-02-18T13:05:00Z2016-01-01T00:00:00ZTitle: The use of a lignosulfonate superplasticizer in repair air lime-metakaolin mortars
Abstract: A superplasticizing admixture of natural origin, lignosulfonate (LS), was incorporated to air lime mortars sometimes modified with a pozzolanic additive, metakaolin, to obtain a new range of repair mortars to be applied in Built Heritage.
LS improved the flowability of the air lime samples and showed good slump retention over time: for example, after 150 minutes of the air lime pastes preparation, blends with LS lost only ca. 13% of the slump value. Experimental results showed that LS interfered with the carbonation due to its ability to form Ca2+ complexes.
Adsorption isotherms and zeta potential measurements showed that LS was scarcely adsorbed onto lime and C-S-H particles. Due to its branchy structure, LS exhibited an adsorption mechanism leading to steric hindrance as the main responsible mechanism for avoiding flocculation. The presence of free LS molecules in the dispersion was seen to improve the plasticizing effect of this polymer. Flexural and compressive strengths as well as the durability in the face of freezing-thawing cycles of these mortars were also determined to assess the applicability of these repair mortars.2016-01-01T00:00:00Z