49,408 research outputs found

    Development and characterization of zein and PVP nanofibers loaded with curcumin and linolenic acid for local treatment of periodontal disease

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    Paradontalna bolezen predstavlja kronińćno vnetje obzobnih tkiv, ki nastane zaradi prekomernega imunskega odziva na poruŇ°eno ravnovesje bakterij v oralnem biofilmu. Za zdravljenje se raziskujejo imunomodulatorne uńćinkovine, med katere sodita tudi kurkumin in linolenska kislina. Lokalni dostavni sistemi z aplikacijo v obzobni Ňĺep predstavljajo velik potencial za zdravljenje paradontalne bolezni, zato je bil namen magistrske naloge razviti in ovrednotiti nanovlakna iz zeina in polivinilpirolidona (PVP) z vgrajenima kurkuminom in linolensko kislino. Nanovlakna smo razvili z elektrostatskim sukanjem polimernih raztopin. Za optimizacijo in boljŇ°e razumevanje procesa smo uporabili dva nańćrta eksperimentov, s pomońćjo katerih smo razvili zein/PVP vlakna z 10 % (m/m) linolensko kislino. V izbrani formulaciji smo vgradili kurkumin z razlińćno vsebnostjo in vlakna fizikalno-kemijsko ovrednotili. Ocetno kislino smo izmed preizkuŇ°anih topil izbrali, ker je raztapljala oba polimera, linolensko kislino in delno kurkumin ter je bila ustrezna za proces elektrostatskega sukanja. Ugotovili smo, da celokupna koncentracija polimera poveńćuje premer vlaken, deleŇĺ zeina zmanjŇ°uje premer vlaken in poveńćuje relativni standardni odklon premera vlaken, deleŇĺ linolenske kisline pa relativni standardni odklon premera vlaken zmanjŇ°uje. Razvili smo model, ki je zmoŇĺen priporońćiti primerno izbiro formulacijskih spremenljivk za Ňĺelen premer nanovlaken. UspeŇ°no smo razvili zein/PVP nanovlakna z 10 % (m/m) linolensko kislino in 10 % (m/m) kurkuminom z minimalnim povpreńćnim premerom ‚Āď640 nm in vlakna z maksimalnim povpreńćnim premerom ‚Āď2500 nm. S prouńćevanjem morfologije nanovlaken smo ugotovili, da so tanjŇ°a nanovlakna okrogla z gladko povrŇ°ino, debelejŇ°a vlakna pa so bolj ploŇ°ńćata z nagubano povrŇ°ino. Na osnovi meritev stińćnega kota lahko sklepamo na hidrofilnost in veliko poroznost mreŇĺe nanovlaken. Glede na rezultate diferenńćne dinamińćne kalorimetrije in analize slik vrstińćnega elektronskega mikroskopa sklepamo, da je kurkumin v nanovlaknih delno v obliki amorfne disperzije, delno pa kristalinińćni obliki. S Fourierjevo transformacijsko infrardeńćo spektroskopijo pa smo zaznali interakcije med linolensko kislino in kurkuminom, ki so bile prisotne samo v nanovlaknih. Razvita nanovlakna predstavljajo prvi korak k razvoju uńćinkovite formulacije za zdravljenje paradontalne bolezni.Periodontal disease is a chronic inflammation of periodontal tissues caused by an excessive immune response to the disturbed balance of bacteria in the oral biofilm. Immunomodulatory agents such as curcumin and linolenic acid are among drugs under investigation. Local delivery systems administered into the periodontal pocket have great potential for the treatment of periodontal disease. Therefore, the aim of this master\u27s thesis was to develop and characterize zein and polyvinylpyrrolidone (PVP) nanofibers with curcumin and linolenic acid. Nanofibers were developed by electrospinning polymer solutions. To improve the understanding of the process and to optimize it, two designs of experiments were developed by which we developed zein/PVP fibers with 10% (w/w) linolenic acid. Further, curcumin was also incorporated into two of the selected formulations and the fibers produced were characterized physicochemically. Of the solvents tested, acetic acid was selected because it dissolves both polymers, linolenic acid and partially curcumin, and is also suitable for the electrospinning process. It was found that the higher total polymer concentration increased the fiber diameter, while the increased content of zein decreased the fiber diameter and increased the relative standard deviation of fiber diameter. In addition, the increased content of linolenic acid decreased the relative standard deviation of the fiber diameter. The developed model can recommend the appropriate choice of formulation variables for the desired nanofiber diameter. Zein/PVP nanofibers with 10% (w/w) linolenic acid and 10% (w/w) curcumin with a minimum average diameter of ‚Āď640 nm and fibers with a maximum average diameter of ‚Āď2500 nm were successfully developed. By examining the morphology of nanofibers, we found that the thinner nanofibers were round and had a smooth surface, while the thicker fibers were flatter and had a wrinkled surface. The contact angle analysis showed that the nanofibers were hydrophilic and their mesh was highly porous. The results of differential dynamic calorimetry and scanning electron microscopy image analysis suggest that part of curcumin in the nanofibers was in the form of amorphous dispersion and part of it in a crystalline form. Using Fourier transform infrared spectroscopy, interactions between linolenic acid and curcumin were detected in the nanofibers. The developed nanofibers represent the first step in developing of an effective formulation for the treatment of periodontal disease

    Sustainability analysis of interior coatings for the prevention of fungal development

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    The construction sector is currently challenged by environmental concerns, reducing energy consumption, and optimising the use of raw materials, hence the need to use new technologies and materials that have a better lifecycle performance. Recycling end-of-life materials or using industrial by-products is a solution in which resources are used efficiently. The considerable contribution of the production of hydraulic lime mortars to the environment, especially in relation to carbon dioxide emissions, is noteworthy. The study and use of nanotechnology and by-products, such as microgranulated corks, are solutions for more sustainable options, as they are more durable, and their properties are similar to conventional mortars. In this study, we explored the environmental benefits of mortars; to this end, we added different percentages of nano-TiO2 and microgranulated cork that can be used in the production of mortars based on hydraulic lime but with antifungal properties. With the analysed results, we verified that these two additives, besides presenting benefits regarding antifungal properties, are viable alternatives to chemical biocides and sustainable options for the mortar industry to improve its environmental performance. The best environmental performance is obtained with mortar with 2% microgranulated cork

    Produtos alternativos √† carne: argumentos, implica√ß√Ķes e as solu√ß√Ķes da ind√ļstria alimentar

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    Atualmente, t√™m-se questionado os princ√≠pios das dietas omn√≠voras, por raz√Ķes de sa√ļde p√ļblica, sustentabilidade ambiental e bem-estar dos animais. Este paradigma, criou os incentivos para que se considerem as dietas baseada em plantas (DBP) e os produtos alternativos √† carne (PAC) como solu√ß√Ķes alternativas √†s dietas omn√≠voras, para responder √†s preocupa√ß√Ķes pela centraliza√ß√£o nos produtos de origem animal e seus derivados. Num primeiro estudo de revis√£o de literatura que contemplou 68 artigos cient√≠ficos, demonstrou-se que a alimenta√ß√£o de base vegetal est√° associada a benef√≠cios para a sa√ļde humana, preven√ß√£o de doen√ßas cr√≥nicas e potencial contributo para o bem-estar, sustentabilidade ambiental e dos sistemas de produ√ß√£o alimentar. No segundo estudo de revis√£o, englobando 194 artigos cient√≠ficos, conclui-se que os produtos an√°logos a carne s√£o uma solu√ß√£o para a ocorr√™ncia da transi√ß√£o dos produtos de origem animal para vegetal. O sucesso desta transi√ß√£o, do consumo de produtos √† base de carne e de seus derivados, para o crescente consumo de produtos √† base de plantas depender√° de tr√™s grandes condi√ß√Ķes: i) capacidade de elabora√ß√£o de produtos que mimetizem as caracter√≠sticas organol√©ticas e funcionais dos produtos de origem animal; ii) maior ades√£o dos consumidores √† inclus√£o na sua dieta di√°ria; iii) incremento da produ√ß√£o de produtos vegetais que supram as crescentes necessidades do mercado no futuroCurrently, the principles of omnivorous diets have been questioned, for reasons of public health, environmental sustainability, and animal welfare. This paradigm created incentives to consider plant-based diets (PBD) and meat substitutes as alternative solutions to omnivorous diets, to respond to concerns about the centralization on products of animal origin and their derivatives. In a first literature review study that included 68 scientific articles, it was shown that plant-based food is associated with benefits for human health, prevention of chronic diseases and potential contribution to well-being, environmental sustainability, and food production systems. In the second review study, comprising 194 scientific articles, it was concluded that meat analogues products are a solution for the occurrence of the transition from animal to vegetable products. The success of this transition, from the consumption of meat-based products and their derivatives to the growing consumption of plant-based products will depend on three main conditions: i) ability to produce products that mimic the organoleptic and functional characteristics of the products of animal origin; ii) greater consumer adherence to inclusion in their daily diet; iii) increased production of plant products that meet the growing needs of the market in the future

    Design, development, and analysis of hybrid metal-composite tube for industrial application

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    In the aerospace, automotive, printing, and sports industries, the development of hybrid Carbon Fiber Reinforced Polymer (CFRP)-metal components is becoming increasingly important. The coupling of metal with CFRP in axial symmetric components results in reduced production costs and increased mechanical properties such as bending, torsional stiffness, mass reduction, damping, and critical speed compared to the single material-built ones. In this thesis, thanks to a novel methodology involving a rubbery/viscoelastic interface layer, several hybrid aluminum-CFRP prototype tubes were produced. Besides, an innovative system for the cure of the CFRP part has been studied, analyzed, tested, and developed in the company that financed these research activities (Reglass SRL, Minerbio BO, Italy). The residual thermal stresses and strains have been investigated with numerical models based on the Finite Element Method (FEM) and compared with experimental tests. Thanks to numerical models, it was also possible to reduce residual thermal stresses by optimizing the lamination sequence of CFRP and determining the influence of the system parameters. A novel software and methodology for evaluating mechanical and damping properties of specimens and tubes made in CFRP were also developed. Moreover, to increase the component's damping properties, rubber nanofibers have been produced and interposed throughout the lamination of specimens. The promising results indicated that the nanofibrous mat could improve the material damping factor over 77% and be adopted in CFRP components with a negligible increment of weight or losing mechanical properties

    Advanced electrospun nanofibrous mats for hindering delamination, improving damping and for sensing of composite laminates

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    Carbon Fiber Reinforced Polymers (CFRPs) display high specific mechanical properties, allowing the creation of lightweight components and products by metals replacement. To reach outstanding mechanical performances, the use of stiff thermoset matrices, like epoxy, is preferred. Laminated composites are commonly used for their ease of manipulation during object manufacturing. However, the natural anisotropic structure of laminates makes them vulnerable toward delamination. Moreover, epoxy-based CFRPs are very stiff materials, thus showing low damping capacity, which results in unwanted vibrations and structure-borne noise that may contribute to delamination triggering. Hence, searching for systems able to limit these drawbacks is of primary importance for safety reasons, as well as for economic ones. In this experimental thesis, the production and integration of innovative rubbery nanofibrous mats into CFRP laminates are presented. A smart approach, based on single-needle electrospinning of rubber-containing blends, is proposed for producing dimensionally stable rubbery nanofibers without the need for rubber crosslinking. Nano-modified laminates aim at obtaining structural composites with improved delamination resistance and enhanced damping capacity, without significantly lowering other relevant mechanical properties. The possibility of producing nanofibers nano-reinforced with graphene to be applied for reinforcing composite laminates is also investigated. Moreover, the use of piezoelectric nanofibrous mats in hybrid composite laminates for achieving self-sensing capability is presented too as a different approach to prevent the catastrophic consequences of possible structural laminate failure. Finally, an accurate, systematic, and critical study concerning tensile testing of nonwovens, using electrospun Nylon 66 random nanofibrous mats as a case study, is proposed. Nanofibers diameter and specimen geometry were investigated to thoroughly describe the nanomat tensile behaviour, also considering the polymer thermal properties, and the number of nanofibers crossings as a function of the nanofibers diameter. Stress-strain data were also analysed using a phenomenological data fitting model to interpret the tensile behaviour better

    Nanofibrous-structured polymers and their engineering applications

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    Monolithic materials cannot always satisfy the demands of today’s advanced requirements. Only by combining several materials at different length-scales, as nature does, the requested performances can be met. Polymer nanocomposites are intended to overcome the common drawbacks of pristine polymers, with a multidisciplinary collaboration of material science with chemistry, engineering, and nanotechnology. These materials are an active combination of polymers and nanomaterials, where at least one phase lies in the nanometer range. By mimicking nature’s materials is possible to develop new nanocomposites for structural applications demanding combinations of strength and toughness. In this perspective, nanofibers obtained by electrospinning have been increasingly adopted in the last decade to improve the fracture toughness of Fiber Reinforced Plastic (FRP) laminates. Although nanofibers have already found applications in various fields, their widespread introduction in the industrial context is still a long way to go. This thesis aims to develop methodologies and models able to predict the behaviour of nanofibrous-reinforced polymers, paving the way for their practical engineering applications. It consists of two main parts. The first one investigates the mechanisms that act at the nanoscale, systematically evaluating the mechanical properties of both the nanofibrous reinforcement phase (Chapter 1) and hosting polymeric matrix (Chapter 2). The second part deals with the implementation of different types of nanofibers for novel pioneering applications, trying to combine the well-known fracture toughness enhancement in composite laminates with improving other mechanical properties or including novel functionalities. Chapter 3 reports the development of novel adhesive carriers made of nylon 6,6 nanofibrous mats to increase the fracture toughness of epoxy-bonded joints. In Chapter 4, recently developed rubbery nanofibers are used to enhance the damping properties of unidirectional carbon fiber laminates. Lastly, in Chapter 5, a novel self-sensing composite laminate capable of detecting impacts on its surface using PVDF-TrFE piezoelectric nanofibers is presented

    Aqueous-phase reforming of water-soluble compounds from pyrolysis bio-oils

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    Aqueous-phase reforming (APR) of model compounds of bio-oil aqueous fraction (AFB) was studied at different operating conditions. Substrate conversion, carbon-to-gas yield (CCgas) and hydrogen and alkanes production were evaluated. Levoglucosan, hydroxyacetone, furfural and acetic acid were selected as representative of AFB and tested in batch APR at different concentrations (1‚Äď5 %wt.), temperatures (175‚Äď220 ‚ó¶C) and reaction times (0.5‚Äď4 h), using 3% (wt.) Pt/CB catalysts. Best results were obtained at 220 ‚ó¶C and 1%, with 70‚Äď90% substrate conversions, 45‚Äď70% CC gas and hydrogen production up to 50 mmol per gram of total organic carbon (TOC). Catalyst stability was checked in APR of levoglucosan during five successive 4 h reaction cycles. The catalyst exhibited high stability, CCgas remained constant and hydrogen production increased and became stable after first reaction cycle with only a slight decrease of TOC conversion. The catalyst with well dispersed metal phase and high contribution of nanoparticles smaller than 2 nm showed a higher production of hydrogen. APR was proved to be a feasible option for the valorisation of AF

    Animal protein-based soft materials for tissue engineering applications

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    Proteins have long been used in coatings for cell culture plates and to supplement cell culture media. Due to their unmatched biocompatibility, biodegradability, bioactivity and immune-privilege, the interest in proteins rapidly advanced for the design and engineering of more complex substrates for biomedical applications. In this chapter, the proteins typically used in the design and fabrication of biomedical devices are presented and discussed, with particular focus in human-based platforms. However, restrictions in the use of protein-derived materials are associated with their limited processability and stability, but to overcome this, multiple bioconjugation techniques have been described and are herein presented. An overview of current protein-based materials that have found clinical application and that have been commercialized is also provided.publishe

    Enhancement of Electromagnetic Wave Shielding Effectiveness by the Incorporation of Carbon Nanofibers‚ÄďCarbon Microcoils Hybrid into Commercial Carbon Paste for Heating Films

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    Carbon microcoils (CMCs) were formed on stainless steel substrates using C2H2 + SF6 gas flows in a thermal chemical vapor deposition (CVD) system. The manipulation of the SF6 gas flow rate and the SF6 gas flow injection time was carried out to obtain controllable CMC geometries. The change in CMC geometry, especially CMC diameter as a function of SF6 gas flow injection time, was remarkable. In addition, the incorporation of H2 gas into the C2H2 + SF6 gas flow system with cyclic SF6 gas flow caused the formation of the hybrid of carbon nanofibers‚Äďcarbon microcoils (CNFs‚ÄďCMCs). The hybrid of CNFs‚ÄďCMCs was composed of numerous small-sized CNFs, which formed on the CMCs surfaces. The electromagnetic wave shielding effectiveness (SE) of the heating film, made by the hybrids of CNFs‚ÄďCMCs incorporated carbon paste film, was investigated across operating frequencies in the 1.5‚Äď40 GHz range. It was compared to heating films made from commercial carbon paste or the controllable CMCs incorporated carbon paste. Although the electrical conductivity of the native commercial carbon paste was lowered by both the incorporation of the CMCs and the hybrids of CNFs‚ÄďCMCs, the total SE values of the manufactured heating film increased following the incorporation of these materials. Considering the thickness of the heating film, the presently measured values rank highly among the previously reported total SE values. This dramatic improvement in the total SE values was mainly ascribed to the intrinsic characteristics of CMC and/or the hybrid of CNFs‚ÄďCMCs contributing to the absorption shielding route of electromagnetic waves
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