Fabric-Reinforced Cementitious Matrix (FRCM) Carbon Yarns with Different Surface Treatments Embedded in a Cementitious Mortar: Mechanical and Durability Studies

Nowadays, FRCM systems are increasingly used for the strengthening and retrofitting of existing masonry and reinforced concrete structures. Their effectiveness strongly depends on the bond that develops at the interface between multifilament yarns, which constitute the reinforcing fabric, and the inorganic matrix. It is well known that fabric yarns, especially when constituted by dry carbon fibers, have poor chemical-physical compatibility with inorganic matrices. For this reason, many efforts are being concentrated on trying to improve the interface compatibility by using different surface treatments on multifilament yarns. In this paper, three different surface treatments have been considered. The first two involve yarn pre-impregnation with flexible epoxy resin or nano-silica coating, while the third one involves a fiber oxidation process. Uniaxial tensile tests were carried out on single carbon yarns to evaluate tensile strength, elastic modulus and ultimate strain before and after surface treatments, and also after yarn exposure to accelerated artificial aging conditions (1000 h in saline or alkaline solutions at 40◦C), to evaluate their long-term behavior in aggressive environments. Pull-out tests on single carbon yarns embedded in a cementitious mortar were also carried out, under normal environmental conditions and after artificial exposure. Epoxy proved to be the most effective treatment, by increasing the yarn tensile strength of 34% and the pull-out load of 138%, followed by nano-silica (+9%; +40%). All surface treatments were shown to remain effective even after artificial environmental exposures, with a maximum reduction of yarn tensile strength of about 13%

Polymeric Coatings for AR-Glass Fibers in Cement-Based Matrices: Effect of Nanoclay on the Fiber-Matrix Interaction

Polymeric coatings are widely used to enhance the load bearing capacity and chemical durability of alkali-resistant glass (AR-glass) textile in cement-based composites. The contact zone between coated yarns and concrete matrix plays a major role to enable the stress transfer and has still to be improved for the full exploitation of the mechanical behavior of the composite. As a new approach, this paper studies how the addition of nanoclay particles in the polymer coating formulation can increase the chemical bond between organic coating and inorganic matrix. This includes the description of the water-based coating preparation by dispersing sodium montmorillonites, whereby the resulting coating nanostructure is characterized by X-ray diffraction and energy dispersive X-ray spectroscopy. Single glass fibers were treated by dip-coating. Atomic force microscopy was used to determine the surface roughness, and the effect on the fiber tensile properties was studied. Moreover, the morphological and chemical characteristics of the coatings were compared with the results obtained from single fiber pull-out (SFPO) tests. It was shown that the incorporation of nanoclays leads to increased interfacial shear strength arising from the ability of nanoclay particles to nucleate hydration products in the fiber-matrix contact zone

Protective Effect of Strawberry Extract against Inflammatory Stress Induced in Human Dermal Fibroblasts

A protracted pro-inflammatory state is a major contributing factor in the development, progression and complication of the most common chronic pathologies. Fruit and vegetables represent the main sources of dietary antioxidants and their consumption can be considered an efficient tool to counteract inflammatory states. In this context an evaluation of the protective effects of strawberry extracts on inflammatory stress induced by E. coli LPS on human dermal fibroblast cells was performed in terms of viability assays, ROS and nitrite production and biomarkers of oxidative damage of the main biological macromolecules. The results demonstrated that strawberry extracts exerted an anti-inflammatory effect on LPS-treated cells, through an increase in cell viability, and the reduction of ROS and nitrite levels, and lipid, protein and DNA damage. This work showed for the first time the potential health benefits of strawberry extract against inflammatory and oxidative stress in LPS-treated human dermal fibroblast cells

Strawberry-Based Cosmetic Formulations Protect Human Dermal Fibroblasts against UVA-Induced Damage

Extreme exposure of skin to Ultraviolet A (UVA)-radiation may induce a dysregulated production of reactive oxygen species (ROS) which can interact with cellular biomolecules leading to oxidative stress, inflammation, DNA damage, and alteration of cellular molecular pathways, responsible for skin photoaging, hyperplasia, erythema, and cancer. For these reasons, the use of dietary natural bioactive compounds with remarkable antioxidant activity could be a strategic tool to counteract these UVA-radiation-caused deleterious effects. Thus, the purpose of the present work was to test the efficacy of strawberry (50 µg/mL)-based formulations supplemented with Coenzyme Q10 (100 µg/mL) and sun protection factor 10 in human dermal fibroblasts irradiated with UVA-radiation. The apoptosis rate, the amount of intracellular reactive oxygen species (ROS) production, the expression of proteins involved in antioxidant and inflammatory response, and mitochondrial functionality were evaluated. The results showed that the synergic topical use of strawberry and Coenzyme Q10 provided a significant (p < 0.05) photoprotective effect, reducing cell death and ROS, increasing antioxidant defense, lowering inflammatory markers, and improving mitochondrial functionality. The obtained results suggest the use of strawberry-based formulations as an innovative, natural, and useful tool for the prevention of UVA exposure-induced skin diseases in order to decrease or substitute the amount of synthetic sunscreen agents

Polyphenol-Rich Strawberry Extract Protects Human Dermal Fibroblasts against Hydrogen Peroxide Oxidative Damage and Improves Mitochondrial Functionality

Strawberry bioactive compounds are widely known to be powerful antioxidants. In this study, the antioxidant and anti-aging activities of a polyphenol-rich strawberry extract were evaluated using human dermal fibroblasts exposed to H2O2. Firstly, the phenol and flavonoid contents of strawberry extract were studied, as well as the antioxidant capacity. HPLC-DAD analysis was performed to determine the vitamin C and β-carotene concentration, while HPLC-DAD/ESI-MS analysis was used for anthocyanin identification. Strawberry extract presented a high antioxidant capacity, and a relevant concentration of vitamins and phenolics. Pelargonidin- and cyanidin-glycosides were the most representative anthocyanin components of the fruits. Fibroblasts incubated with strawberry extract and stressed with H2O2 showed an increase in cell viability, a smaller intracellular amount of ROS, and a reduction of membrane lipid peroxidation and DNA damage. Strawberry extract was also able to improve mitochondrial functionality, increasing the basal respiration of mitochondria and to promote a regenerative capacity of cells after exposure to pro-oxidant stimuli. These findings confirm that strawberries possess antioxidant properties and provide new insights into the beneficial role of strawberry bioactive compounds on protecting skin from oxidative stress and aging

Strawberry (cv. Romina) Methanolic Extract and Anthocyanin-Enriched Fraction Improve Lipid Profile and Antioxidant Status in HepG2 Cells

Dyslipidemia and oxidation of low density lipoproteins (LDL) are recognized as critical factors in the development of atherosclerosis. Healthy dietary patterns, with abundant fruit and vegetable consumption, may prevent the onset of these risk factors due to the presence of phytochemical compounds. Strawberries are known for their high content of polyphenols; among them, flavonoids are the major constituents, and it is presumed that they are responsible for the biological activity of the fruit. Nevertheless, there are only a few studies that actually evaluate the effects of different fractions isolated from strawberries. In order to assess the effects of two different strawberry extracts (whole methanolic extract/anthocyanin-enriched fraction) on the lipid profile and antioxidant status in human hepatocellular carcinoma (HepG2) cells, the triglycerides and LDL-cholesterol content, lipid peroxidation, intracellular reactive oxygen species (ROS) content and antioxidant enzymes’ activity on cell lysates were determined. Results demonstrated that both strawberry extracts not only improved the lipid metabolism by decreasing triglycerides and LDL-cholesterol contents, but also improved the redox state of HepG2 cells by modulating thiobarbituric acid-reactive substances production, antioxidant enzyme activity and ROS generation. The observed effects were more pronounced for the anthocyanin-enriched fraction

Phenolic Compounds Isolated from Olive Oil as Nutraceutical Tools for the Prevention and Management of Cancer and Cardiovascular Diseases

Non-communicable diseases (NCDs) have become the largest contributor to worldwide morbidity and mortality. Among them, cancer and cardiovascular diseases (CVDs) are responsible for a 47% of worldwide mortality. In general, preventive approaches modifying lifestyle are more cost-effective than treatments after disease onset. In this sense, a healthy diet could help a range of NCDs, such as cancer and CVDs. Traditional Mediterranean Diet (MD) is associated by the low-prevalence of certain types of cancers and CVDs, where olive oil plays an important role. In fact, different epidemiological studies suggest that olive oil consumption prevents some cancers, as well as coronary heart diseases and stroke incidence and mortality. Historically, the beneficial health effects of virgin olive oil (VOO) intake were first attributed to the high concentration of monounsaturated fatty acids. Nowadays, many studies indicate that phenolic compounds contained in olive oil have positive effects on different biomarkers related to health. Among them, phenolic compounds would be partially responsible for health benefits. The present work aims to explore, in studies published during the last five years, the effects of the main phenolic compounds isolated from olive oil on different cancer or CVD aspects, in order to clarify which compounds have more potential to be used as nutraceuticals with preventive or even therapeutic properties

Beeswax by-Products Efficiently Counteract the Oxidative Damage Induced by an Oxidant Agent in Human Dermal Fibroblasts

The antioxidant capacity and the phytochemical composition of two by-products from beeswax recycling processes were recently investigated. The aim of the present work was to evaluate the efficacy of one of these by-products, MUD1, against the oxidative stress induced by 2,20-azobis(2-amidinopropane) dihydrochloride (AAPH) in human dermal fibroblast (HDF) cells. After a preliminary viability assay, the protective effect of MUD1 was investigated through the measurement of apoptosis level, the reactive oxygen species (ROS) and nitrite (NO2-) production, the level of protein and lipid biomarkers (carbonyl groups, total glutathione and thiobarbituric acid-reactive substance) of oxidative damage, and the measurement of antioxidant enzymes activities (glutatione peroxidase, glutathione reductase, glutathione transferase, superoxide dismutase and catalase). The obtained results showed that MUD1 exerted protective effects on HDF, increasing cell viability and counteracted the oxidative stress promoted by AAPH-treatment, and improved mitochondria functionality and wound healing capacities. This work shows the antioxidant effects exerted by beeswax by-products, demonstrating for the first time their potential against oxidative stress in human dermal fibroblast cells; however, further research will be necessary to evaluate their potentiality for human health by more deeply in vitro and in vivo studies.The present study was partially funded by the “National Beekeeping Aid Program (Programa Nacional de Ayudas a la Apicultura)”, cofounded by the European Union and assigned to Spanish FEGA and FEAGA agencies. Patricia Reboredo-Rodríguez acknowledges award of a post-doctoral contract from Xunta de Galicia

Surface modification of fabric reinforcements for frcm systems: effect on the mechanical properties and durability

L’utilizzo di sistemi FRCM si sta progressivamente affermando in campo ingegneris- tico come promettente tecnica per il rinforzo e la riabilitazione di strutture in cemento e in muratura. Tuttavia, a causa della mancanza di documentate informazione sulle prestazioni nel tempo di questi materiali compositi, ad oggi poco è noto della loro capacità di resistere all’esposizione a diversi ambienti potenzialmente aggressivi. La complessità nello studiare i diversi meccanismi responsabili per il deterioramento di questi sistemi nel tempo è data dai diversi tipi di stress ambientale a cui il materiale può essere esposto durante la sua vita di servizio, così come dall’ampia varietà di materiali che possono essere impiegati. Inoltre, per rinforzi modificati con coating organici o inorganici, spesso proposti in letteratura per aumentare le capacità di carico del composito, le performance complessive del sistema saranno influenzate dal tipo di coating applicato. Lo scopo principale di questo studio è verificare come diverse tecniche, proposte in letteratura per la modifica dei rinforzi in rete, influenzino la capacità degli FRCM di mantenere inalterate le proprie proprietà meccaniche a seguito dell’esposizione a diversi ambienti. Inoltre, al fine di ottimizzare sia le proprietà meccaniche che la durabilità del composito, è stato studiata l’efficacia di coating a base stirene-butadiene contenenti diverse percentuali di nano argille. I rinforzi in fibra presi in considerazione in questo studio comprendono sia fibre in carbonio che in vetro, le prime note per godere di un ottima stabilità chimica, le seconde soggette a corrosione in ambiente alcalino. Le fibre in carbonio sono state modificate con una soluzione ossidativa, un coating epossidico e un a base di nano silice. L’efficacia dei coating con nano argille è stata studiata su fibre in vetro alcalino resistente appositamente filate per questo progetto al Leibniz Institute für Polymerforschung (IPF) di Dresda, dove è stato condotto parte di questo lavoro. Come caso studio di sistemi commercialmente disponibili si è fatto uso di un rinforzo in fibra di vetro preapprettato con coating stirene-butadiene. I protocolli d’invecchiamento accelerato adottati comprendo: immersione dei provini in soluzioni alcaline e saline ed esposizione a cicli gelo-disgelo. I test sono stati eseguiti sia sul materiale composito che su i suoi componenti (matrice e rete in fibra). L’effetto dei vari ambienti di esposizione sulla matrice cementizia è stato studiato tramite test a flessione e compressione abbinati a cromatografia ionica e diffrazioni a raggi X. Tensil test e pull-out test sono stati eseguiti su singoli yarn al fine di valutare l’effetto dei caoting sulle proprietà meccaniche e la durabilità del rinforzo e del materiale composito. La caratterizzazione del sistema ottenuto con la rete preapprettata è stato eseguito tramite tensile test. Per le fibre realizzate all’IPF sono stati effettuati anche test micro meccanici su filamenti singoli. Analisi FTIR, TGA, DSC, XRD, SEM-EDX e AFM sono state effettuate per la caratterizzazione dei coating e della superficie delle fibre. In generale si è potuto constatare che la stabilità chimica del rinforzo svolge un ruolo secondario nella durabilità del composito, e che sulla base del comportamento delle singole componenti non si possono trarre conclusioni sulla capacità del composito di sottostare l’esposizione a diversi ambienti. Il coating epossidico e quello a base di nano silice sono in grado sia di aumentare l’interazione delle fibre in carbonio con la matrice, che di preservare le proprietà del composito nel tempo. Per i coating contenenti nano argille, un aumento delle capacità di carico è stato osservato nelle prove di pull-out al crescere della percentuale di nano argille. Tuttavia i migliori risultati in termine d’interazione coating-matrice e durabilità del composito si ottengono per un quantitativo di nano argille pari al 5%.Over the last decades Fabric Reinforced Cementitious Matrix (FRCM) systems have gained great interest as a promising technique for the reinforcement and rehabilitation of concrete and masonry structures. However, due to the lack of anecdotal information or documented long-term performance, at present relatively few is known about the durability of these materials under different environmental exposure. Therefore, a comprehensive understating of the different mechanisms responsible for the deterioration of FRCM systems over time is still an issue. This is due to the different kind of environmental stress that the composite may have to withstand during its life, and on the great varieties of materials (cementitious matrices and fabrics) that can be employed. Moreover, when textile are modified with some kind of coatings, as it has been proposed by different studies to improve the mechanical properties of the composite, the overall performance of the composite over time will also be affected by the different kind of coatings possibly applied. The primary aim of this work is to understand how different techniques, proposed in the literature for the modification of FRCM reinforcements, influence the ability of the composite to withstand environmental exposures. Secondary, different coatings based on a Carboxylated Styrene Butadiene (SB) polymer formulated with increasing percentage of nanoclay were investigated as modification technique to obtain a composite with improved mechanical properties and durability. Chemically stable carbon fibers as well as AR-glass fibers, which are known to undergo chemical degradation in alkaline environments, have been used. Carbon fibers have been modified with an oxidative solution, a nanosilica coating and an epoxy coating. The experimental nanoclay-SB coatings were applied on AR-glass fibers specifically spun for this project at the Leibniz Institut für Polymerforschung Dresden (IPF), where part of this work has been conducted. Durability test on commercially available reinforcements were also conducted using a Styrene Butadiene preimpregnated AR-glass fabric. Aging protocols adopted include immersion in saltwater and alkaline solution and freeze–thaw cycles. Tests were performed on both the composite material and its components. Compressive and three point bending test were employed to evaluate the change in the matrix properties after environmental exposure. Ionic chromatography and X-ray diffraction (XRD) were used to investigate possible change in the chemical composition of the matrix. Tensile test on single yarn and pull-out test were respectively employed to evaluate the effect of different coatings on the durability of the reinforcement and the composite. Characterization of the composite based on the AR-Glass commercial fabric were performed on FRCM coupons. For the IPF fibers single fiber tensile test and quasi-static single fiber pull-out test were also performed. FTIR, TGA, DSC, XRD, SEM-EDX and AFM analysis were employed for the characterization of the coatings as well as the surfaces of the modified fibers. In general, it could be observed that the chemical stability of the reinforcement plays a minor role on the durability of the composites, and that no conclusion on the ability of the composite to withstand different environmental exposure can be drawn on the base of the components’ behavior. Epoxy resin and nanosilica coatings were both found to improve the interaction of the reinforcement with the matrix and simultaneously preserve the mechanical properties of the composite over time. For the nanoclay coatings an increase in the pull-out load was observed for high amount of nanoclay. However, the best results in terms of polymer-matrix interaction and durability were obtained with the addition of 5% of nanoclay in the polymeric coating

Fabric-Reinforced Cementitious Matrix (FRCM) Carbon Yarns with Different Surface Treatments Embedded in a Cementitious Mortar: Mechanical and Durability Studies

Nowadays, FRCM systems are increasingly used for the strengthening and retrofitting of existing masonry and reinforced concrete structures. Their effectiveness strongly depends on the bond that develops at the interface between multifilament yarns, which constitute the reinforcing fabric, and the inorganic matrix. It is well known that fabric yarns, especially when constituted by dry carbon fibers, have poor chemical-physical compatibility with inorganic matrices. For this reason, many efforts are being concentrated on trying to improve the interface compatibility by using different surface treatments on multifilament yarns. In this paper, three different surface treatments have been considered. The first two involve yarn pre-impregnation with flexible epoxy resin or nano-silica coating, while the third one involves a fiber oxidation process. Uniaxial tensile tests were carried out on single carbon yarns to evaluate tensile strength, elastic modulus and ultimate strain before and after surface treatments, and also after yarn exposure to accelerated artificial aging conditions (1000 h in saline or alkaline solutions at 40 &deg;C), to evaluate their long-term behavior in aggressive environments. Pull-out tests on single carbon yarns embedded in a cementitious mortar were also carried out, under normal environmental conditions and after artificial exposure. Epoxy proved to be the most effective treatment, by increasing the yarn tensile strength of 34% and the pull-out load of 138%, followed by nano-silica (+9%; +40%). All surface treatments were shown to remain effective even after artificial environmental exposures, with a maximum reduction of yarn tensile strength of about 13%