Sol-Gel Coating Membranes for Optical Fiber Sensors for Concrete Structures Monitoring

The use of advanced sensing devices for concrete and reinforced concrete structures (RCS) is considered a rational approach for the assessment of repair options and scheduling of inspection and maintenance strategies. The immediate benefits are cost reduction and a reliable prevention of unpredictable events. The use of optical fiber sensors (OFS) for such purposes has increased considerably in the last few years due to their intrinsic advantages. In most of the OFS, the chemical transducer consists of immobilized chemical reagents placed in the sensing region of the optical sensor by direct deposition or by encapsulation in a polymeric matrix. The choice of the support matrix impacts directly on the performance of the OFS. In the last two decades, the development of OFS functionalized with organic–inorganic hybrid (OIH) sol–gel membranes have been reported. Sol–gel route is considered a simple method that offers several advantages when compared to traditional synthesis processes, allowing to obtain versatile materials with unique chemical and physical properties, and is particularly valuable in the design of OIH materials. This review will provide an update of the current state-of-the-art of the OFS based on OIH sol-gel materials for concrete and RCS since 2016 until mid-2021. The main achievements in the synthesis of OIH membranes for deposition on OFS will be discussed. The challenges and future directions in this field will also be considered, as well as the main limitations of OFS for RCS monitoring.

In situ gelation of aqueous sulfuric acid solution for fuel cells

In situ polymerization with acrylamide (AM) as the monomer and divinylbenzene (DVB) as a crosslinker in aqueous sulfuric acid solution resulted in gel membranes applicable in fuel cells.

Development and Characterization of Biointeractive Gelatin Wound Dressing Based on Extract of Punica granatum Linn

Punica granatum Linn (pomegranate) extracts have been proposed for wound healing due to their antimicrobial, antioxidant, and anti-inflammatory properties. In this work, we designed biointeractive membranes that contain standard extracts of P. granatum for the purpose of wound healing. The used standard extract contained 32.24 mg/g of gallic acid and 41.67 mg/g of ellagic acid, and it showed high antioxidant activity (the concentration of the extract that produces 50% scavenging (IC50) 1.715 µg/mL). Compared to the gelatin-based membranes (GEL), membranes containing P. granatum extracts (GELPG) presented a higher maximal tension (p = 0.021) and swelling index (p = 0.033) and lower water vapor permeability (p = 0.003). However, no difference was observed in the elongation and elastic modulus of the two types of membranes (p > 0.05). Our wound-healing assay showed that a GELPG-treated group experienced a significant increase compared to that of the control group in their wound contraction rates on days 3 (p < 0.01), 7 (p < 0.001), and on day 14 (p < 0.001). The GELPG membranes promoted major histological changes in the dynamics of wound healing, such as improvements in the formation of granular tissue, better collagen deposition and arrangement, and earlier development of cutaneous appendages. Our results suggest that a biointeractive gelatin-based membrane containing P. granatum extracts has a promising potential application for dressings that are used to treat wounds.

Characterising the diffusion of biological nanoparticles on fluid and cross-linked membranes

“Nanoparticle diffusion on fluid and gel membranes is qualitatively different.”