https://repositorio.ufpb.br/jspui/handle/tede/440 PPGCEM Sat, 25 Jul 2026 20:36:03 GMT 2026-07-25T20:36:03Z https://repositorio.ufpb.br/jspui/handle/123456789/38278 Título: Desenvolvimento e avaliação in vitro de sistemas de liberação controlada de drogas para o tratamento da leishmaniose cutânea à base de nanofibran de PLA/PEO/ANPOTERICINA B produzidas por solution blow spinning (SBS) Autor(es): Ferreira, Kaline do Nascimento Orientador: Medeiros, Eliton Souto de Abstract: Cutaneous leishmaniasis (CL) is an infectious parasitic disease caused by the protozoan of the Leishmania genus, which promotes ulcers in exposed areas of the skin. Amphotericin B (AmB) is one of the drugs used in the treatment. However, its clinical use has limitations intravenously because of its high toxicity and low solubility, making it attractive to investigate vehicles for topical application as a safer way. Thus, in this work a nanostructured topical drug delivery system (TDDS) was proposed using the solution blow spinning (SBS) technique. Fibers of blends of poly(ethylene oxide), PEO, and poly(lactic acid), PLA, with and without AmB were produced by SBS. PEO/PLA fibers in two different weight ratios 50:50 and 70:30, with 0, 0.25, and 1.0% AmB were produced in the form of mats that were morphologically characterized by scanning electron microscopy ( SEM), thermally by thermogravimetry (TG) and differential scanning calorimetry (DSC) and microstructurally by Fourier transform infrared spectroscopy (FTIR) and the degree of hydrophobicity of its surface was verified through the contact angle. The determination of the AmB release profile, the efficiency of incorporation and the drug load were evaluated by spectroscopy (UV-Vis). The degree of swelling of the samples was determined. The release curves were fitted by kinetic models to provide crucial information about the function of the material systems that constitute them. In vitro assays of leishmanicidal activity were determined in promastigote forms of Leishmania amazonensis. The results show that the systems produced by SBS consist of rough fibers for all compositions. AmB was incorporated into the nanofibers and the materials were shown to be thermally stable within the physiological temperature range. The significant increase in drug incorporation occurred in structures with higher proportions of PLA, which has hydrophobic character, higher contact angles, however, the maximum controlled release (88%) after 14 days was found in samples with higher proportions of PEO and AmB . The Peppas-Sahlin model showed the best mathematical fit (R2 ≥ 0.95). The 50:50 samples showed non-Fickian transport, indicative of the combination of drug diffusion mechanisms and polymeric erosion. On the other hand, dressings with higher proportions of PEO showed the Fickian diffusion mechanism, in addition to higher degrees of swelling. All the nanostructured topical drug delivery system with AmB showed leismanicidal activity within 72 h, the highest activities were found for samples with 1.00% of the drug. The results obtained suggest that TDDS control the availability of AmB and have leishmanicidal activity with potential to be used in the local treatment of CL. Editor: Universidade Federal da Paraíba Tipo: Tese Wed, 23 Mar 2022 00:00:00 GMT https://repositorio.ufpb.br/jspui/handle/123456789/38278 2022-03-23T00:00:00Z https://repositorio.ufpb.br/jspui/handle/123456789/38265 Título: Desenvolvimento de sistemas poliméricos à base de quitosana, breu e cera de carnaúba com potencial ação nematicida obtidos por ultrassom Autor(es): Almeida, Carolina Lima de Orientador: Medeiros, Eliton Souto de Abstract: The damage caused by plant-parasitic nematodes in agriculture represents a global challenge, with significant productivity losses in crops such as soybeans. Conventional control of these pathogens often relies on synthetic chemical nematicides, which, although effective, pose risks to human health and the environment. Given this scenario, the pursuit of sustainable and safe alternatives is urgently needed. This thesis explored the potential of chitosan in combination with bioactive components of natural origin, carnauba wax (Copernicia prunifera) and rosin (Pinus), to develop film-forming systems with potential nematicidal activity. The study innovated by employing ultrasound as a processing method to obtain homogeneous and stable suspensions, demonstrating that this technique not only considerably reduces preparation time (from 24 hours to 20 minutes) but also promotes significant morphological and surface modifications. DSC and FTIR characterizations confirmed that ultrasound processing does not chemically alter the components, preserving their thermal and functional properties. SEM analyses revealed that ultrasound directly influences film topography, and these morphological changes correlated directly with wettability assays, in which ultrasound-processed samples mostly exhibited a reduced contact angle, indicating increased hydrophilicity—a desirable characteristic for seed coating applications. Nematode tests showed that the film containing rosin achieved 50% mortality within 72 h, a value six times higher than the control. Carnauba wax also demonstrated nematicidal effectiveness, albeit to a lesser extent (20% at 72 h), contributing to a multifunctional approach. In summary, this research not only demonstrates the feasibility of using biopolymers and natural compounds as alternatives to traditional nematicides but also establishes well-founded correlations between processing, morphology, wettability, and biological activity. The results pave the way for future studies focused on active release kinetics and tests under real field conditions, contributing to more sustainable and safe agriculture. Editor: Universidade Federal da Paraíba Tipo: Tese Thu, 19 Mar 2026 00:00:00 GMT https://repositorio.ufpb.br/jspui/handle/123456789/38265 2026-03-19T00:00:00Z https://repositorio.ufpb.br/jspui/handle/123456789/38082 Título: Influência da adição de Nb e Cr nas propriedades microestruturais e mecânicas de uma liga CuAlMn Autor(es): Caluête, José de Queiroz Orientador: Oliveira, Danniel Ferreira de Abstract: This work investigates the effects of chromium (Cr) and niobium (Nb) additions on the microstructural, mechanical, electrochemical, and functional properties of Cu–Al–Mn shape memory alloys. The alloys were produced by induction furnace melting, followed by homogenization heat treatment and quenching, and characterized using techniques such as optical microscopy, scanning electron microscopy, corrosion resistance testing, and microhardness measurements. The results demonstrate that Cr and Nb promote significant grain refinement, the formation of Al–Cr- and Al–Nb-rich precipitates, an increase in the fraction of 18R martensite, and improvements in the structural stability of martensite. Microhardness tests and X-ray diffraction (XRD) confirmed hardening and changes in phase equilibrium, while energy-dispersive spectroscopy (EDS) validated the incorporation of the alloying elements. Electrochemical analyses showed that the isolated additions of Cr and Nb increase corrosive activity; however, when combined, these elements exhibit a synergistic effect, strengthening the passive film and improving corrosion resistance. The observed increase in electrical resistivity and in the e/a value reinforces the influence of these elements on the electronic behavior and martensitic stability. Thus, Cr and Nb demonstrate strong potential to enhance mechanical reliability, structural and chemical integrity, and to ensure the stability of the functional properties of the alloy. Editor: Universidade Federal da Paraíba Tipo: Tese Mon, 15 Dec 2025 00:00:00 GMT https://repositorio.ufpb.br/jspui/handle/123456789/38082 2025-12-15T00:00:00Z https://repositorio.ufpb.br/jspui/handle/123456789/38036 Título: Efeito de fibras de sisal em compósitos cimentícios impressos em 3D submetidos a elevadas temperaturas Autor(es): Medeiros, Fernanda Karolline de Orientador: Anjos, Marcos Alyssandro Soares dos Abstract: When exposed to high temperatures, 3D-printed cementitious composites (3DP-CC) often exhibit delamination and poor interlayer bonding. This study aims to develop a 3D-printable cementitious composite reinforced with sisal fibers (3DP-SFCC) and to experimentally evaluate the impact of elevated temperatures on the mechanical, physical, and microstructural behavior of both printed and cast specimens. The 3DP-SFCC mixtures were developed with appropriate buildability for extrusion-based printing systems, incorporating sisal fibers of 6 mm and 12 mm in length at volumetric contents of 0,5% and 1,0%. The mixes also included limestone filler and metakaolin. Extrudability, rheological properties, and green strength were evaluated, and physical, mechanical, and microstructural properties were assessed before and after exposure to 200, 400, 600, and 800 °C. The heat propagation through the printed composites was evaluated using thermocouples installed at eight different points of blocks heated to 400 and 600 °C. Incorporating sisal fibers improved green strength but reduced the mechanical performance of unheated 3DP-SFCC in the hardened state. However, at high temperatures, tests demonstrated that sisal fibers prevented interlayer adhesion loss up to 400 °C, while fiber-free mixtures showed a ~37% reduction in interlayer adhesion at the same temperature. Sisal fibers significantly reduced the losses in compressive strength with heating. Between room temperature and 600 °C, the compressive strength decreased by 34% in REF-C and by only 0.3% in SF05%12 in the Y direction. The damage caused by heating was mitigated, especially with the use of 12 mm fibers, and the impact of heating on the anisotropy induced by the 3D printing process was reduced, reinforcing that 3DP-SFCC exhibits improved performance in environments prone to elevated temperatures. The incorporation of sisal fibers altered the heat propagation through the printed composites, modifying the preferential heat transfer path from the interlayer region to the intralayer region, thereby reducing the thermal gradient across the material and minimizing its effects. Editor: Universidade Federal da Paraíba Tipo: Tese Fri, 31 Oct 2025 00:00:00 GMT https://repositorio.ufpb.br/jspui/handle/123456789/38036 2025-10-31T00:00:00Z