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Item type:Publication, Bacterial-Polymer-Based Electrolytes: Recent Progress and Applications(American Chemical Society, 2020-12-28)Bacteria can naturally synthesize a wide range of biopolymers that have appealing material properties for numerous applications. In the past decade, the development of green electronics based on bacterial polymers has gained major attention. Polymer electrolytes are key components in electrochemical devices owing to their mechanical properties, thermal stability, and ionic conductivity. The present review focuses on the recent progress of bacterial-polymer-based electrolytes and their applications in electrochemical energy conversion and storage. First, we described the ion transfer mechanism of polymer electrolytes and the multiple approaches for improving ionic conductivity and mechanical properties. Then, we summarized the composition, performance, and approaches applied for the development of multiple bacterial polymer electrolytes, namely, polysaccharides, polyanhydrides, and polyesters. Lastly, the practical applications of bacterial-polymer-based electrolytes in electrochemical energy storage and conversion, namely, fuel cells, batteries, supercapacitors, and other electrochemicals, are reviewed. Bacterial polymer electrolytes are presented as a fruitful, eco-friendly, and high-performance alternative for traditional solid polymer electrolytes. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Mechanical properties of calcite- and aragonite-based structures by nanoindentation tests(ICE Publishing, 2020-06-05)Nacre has been considered as one of the most important models for the development of hard bioinspired materials. This aragonite-based layered structure has been extensively studied because of its excellent mechanical properties, superior to those of monolithic aragonite. Calcite-based seashells have received less attention, as they display lower hardness and Young's modulus. However, layered calcitic structures also have a superior fracture toughness value compared with monolithic calcite. In this paper, seashells of six species were studied by correlating the mechanical properties of the calcite- and aragonite-based layers with their mineral building blocks. Morphological studies revealed nacreous and fibrous prismatic microstructures for aragonite-based layers, whereas calcite-based layers have prismatic and foliated microstructures. The hardness and stiffness of the aragonitic structures were slightly higher than those of calcite. A toughening factor was calculated comparing the fracture toughness of the aragonitic and calcitic layers with the toughness of monolithic aragonite and calcite. The toughening factors of calcitic and aragonitic structures were in the same range (1.6-9.2). - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Synthesis of highly stable κ/ι-hybrid carrageenan micro- and nanogels via a sonication-assisted microemulsion route(SAGE Publishing, 2020-08-01)Novel carrageenan micro- and nanogels were developed via a sonication-assisted microemulsion processing route. The diameter of the dry samples ranged 197.3 −421.35 nm whereas the diameter of the samples suspended in water ranged 467.8–605.9 nm. Hybrid κ/ι-carrageenan, rather than κ- or ι-carrageenan was used for the first time for the preparation of micro- and nanogels. KCl was used as a cross-linking agent and Tween 80 was used as surfactant. The micro- and nanogels suspended in water were found to simultaneously exhibit a lower diameter, and a lower swelling ratio with higher Tween 80 content. The micro- and nanogel suspension yields a zeta potential value of −50.5 mV, superior to values reported elsewhere for pure κ- or ι-carrageenan micro- and nanogels. The high stability was attributed to the high hydrophile-lipophile balance (HLB = 15) value of Tween 80. These results suggest that hybrid κ/ι-carrageenan micro- and nanogels are promising candidates for smart therapeutics applications. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Molecular α-relaxation process of exopolysaccharides extracted from Nostoc commune cyanobacteria(Elsevier, 2020-10-15)Broadband dielectric spectroscopy was used to investigate the molecular α-relaxation of the exopolysaccharides (EPS) extracted from Nostoc commune cyanobacteria. The EPS were modified in different ways. EPS were carboxymethylated to obtain carboxymethyl-exopolysaccharides (CEPS). EPS and CEPS were doped with ammonium iodide and 1-butyl-3-methylimidazolium chloride. An α relaxation process was observed for all specimens. The temperature dependence of the relaxation times for pure and doped, EPS and CEPS polymers exhibited non-Arrhenius behavior. This relaxation process was associated with the glass transition of the complex heteropolysaccharides produced by the cyanobacteria. The molecular mobility at the glass transition, Tg, was affected by both the carboxymethylation treatment and the doping. The fragility index also decreased for the doped specimens, which may be attributed to an increase in the mobility of the polymer chains due to the plasticizing effect of the doping agents. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Tailoring size and release kinetics of κ/ι-hybrid carrageenan microgels via a surfactant-assisted technique(Taylor & Francis, 2020-01-25)κ/ι-Hybrid carrageenan microgels were prepared to be used as drug delivery systems. A surfactant-assisted microemulsion technique was used. Tween® 80 was used as surfactant and enrofloxacin was used as a model drug. The results showed that the amount of surfactant used during processing determines the size of the microgels as well as the amount of enrofloxacin that can be loaded. At low surfactant content, the initial burst release effect is dominant whereas at high surfactant content the burst release effect is negligible and the Fickian diffusion mechanism is dominant. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Marine macroinvertebrates inhabiting plastic litter in Peru(Elsevier, 2021-06-01)Marine litter, such as plastic bags, bottles, fabrics, or fishing gear, serve as a shelter for many marine organisms that are likely to colonize artificial substrata. Such assemblages can potentially turn marine litter into vectors of alien invasive species (AIS). Here, we report the abundance and diversity of macroinvertebrates inhabiting marine litter in Peruvian beaches. Results indicate that most of the fouled items found came from land-based sources (81.5%) and Bivalvia was the most abundant class (53.5%), mainly composed of the mussel Semimytilus algosus. No significant differences were found in the abundance and diversity of macroinvertebrates (class level) among sampling sites or sources of litter. Polypropylene and low-density polyethylene items were most frequently found with fouled biota. Although none of the identified species were non-native to the coast of Peru, we discuss marine litter as a potential source of AIS in this region. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Binational survey of personal protective equipment (PPE) pollution driven by the COVID-19 pandemic in coastal environments: abundance, distribution, and analytical characterization(Elsevier, 2021-12-11)In the present contribution, two nationwide surveys of personal protective equipment (PPE) pollution were conducted in Peru and Argentina aiming to provide valuable information regarding the abundance and distribution of PPE in coastal sites. Additionally, PPE items were recovered from the environment and analyzed by Fourier transformed infrared (FTIR) spectroscopy, Scanning electron microscopy (SEM) with Energy dispersive X-ray (EDX), and X-ray diffraction (XRD), and compared to brand-new PPE in order to investigate the chemical and structural degradation of PPE in the environment. PPE density (PPE m−2) found in both countries were comparable to previous studies. FTIR analysis revealed multiple polymer types comprising common PPE, mainly polypropylene, polyamide, polyethylene terephthalate, and polyester. SEM micrographs showed clear weathering signs, such as cracks, cavities, and rough surfaces in face masks and gloves. EDX elemental mapping revealed the presence of elemental additives, such as Ca in gloves and face masks and AgNPs as an antimicrobial agent. Other metals found on the surface of PPE were Mo, P, Ti, and Zn. XRD patterns displayed a notorious decrease in the crystallinity of polypropylene face masks, which could alter its interaction with external contaminants and stability. The next steps in this line of research were discussed. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Ulvan-based materials doped with lithium sulfate salts as solid biopolymer electrolytes for energy storage applications(Elsevier B.V., 2024-03-01)The conversion of algae biomass into high-value technological materials can promote the utilization of green algae and mitigate issues such as green tides and biofouling. This paper reports, for the first time, the utilization of ulvan in the production of solid biopolymer electrolytes (SBEs) doped with lithium sulfate salts. Ulvan were obtained from the green algae Ulva nematoidea using two different processing methods: hot water extraction and alkaline extraction. Hot water extraction enables the extraction of ulvan chains with a high molecular weight. In contrast, alkaline extraction produces a heterogeneous molecular weight distribution with Mw values of 730 kDa, 339 kDa, and 380 kDa. Frequency-dependent conductivity plots showed that SBEs made from ulvan extracted using the alkaline route featured higher conductivity than those SBEs made from water-extracted ulvan. The highest conductivity was obtained with ulvan extracted using the alkaline procedure, measuring 1.73 × 10−5 S/cm (tested at 10 MHz and 80 °C). The open conformation and low molecular weight of the ulvan extracted using the alkaline route would promote the segmental movement of ulvan chains and the mobility of Li+ ions. The results showed that ulvan can be used to produce solid-state electrolytes (SBEs) doped with Li-ion salt. The extraction procedure, Li-ion salt concentration, temperature, and frequency are essential variables that determine the conductivity of SBEs. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Optimización de la solución absorbente del contaminante gaseoso ácido sulfhídrico (H2S) empleando polisacáridos ulvan(2023-06-30)La presencia de ácido sulfhídrico (H2S) en el medio ambiente representa un peligro para la salud de las personas. Los métodos convencionales para la detección de H2S requieren del uso de soluciones captadoras, las cuales contienen sulfato de cadmio (CdSO4), hidróxido de sodio (NaOH) y arabinogalactano, que a su vez puede provocar daños en la salud por una constante exposición. En el presente trabajo se validó el uso de polisacáridos Ulvan, como aditivo reemplazante en la preparación de la solución absorbente del contaminante gaseoso ácido sulfhídrico (H2S) según la metodología COVENIN 3571:2000 Calidad de aire. Determinación de la concentración sulfuro de hidrogeno (H2S(g)) en la atmosfera. Los resultados obtenidos en la validación del método modificado (porque se modificó la solución absorbente) fueron analizados a través de parámetros como linealidad, precisión, veracidad, selectividad, rango de trabajo, límite de detección, límite de cuantificación, robustez e incertidumbre. Se determinó que los datos obtenidos fueron precisos debido a que el % de desviación estándar relativa (RSD) de repetibilidad fue menor al %RSD de Horwitz. Además, a partir de la curva de calibración, se comprobó la linealidad satisfactoria del método modificado con polisacáridos Ulvan debido a que el coeficiente de determinación (R2) fue superior a 0.995. Los valores límite de detección (LOD) y cuantificación (LDQ) de H2S fueron de 0.47 μg/m3 y 1.88 μg/m3, respectivamente. Finalmente, las evaluaciones a distintos tiempos de desarrollo del color azul de metileno fueron robustos, y se pueden trabajar en condiciones normales sin afectar la reproducibilidad de los resultados. El método modificado y optimizado con la presencia de polisacáridos Ulvan fue validado cumpliendo con los parámetros requeridos de aceptación propuestos. De esta manera, se concluyó que el Ulvan representan una potencial alternativa para aplicaciones en la detección de gases contaminantes como el H2S(g). - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Carbon Quantum Dots Based on Marine Polysaccharides: Types, Synthesis, and Applications(Multidisciplinary Digital Publishing Institute (MDPI), 2023-06-01)The marine environment offers a vast array of resources, including plants, animals, and microorganisms, that can be utilized to extract polysaccharides such as alginate, carrageenan, chitin, chitosan, agarose, ulvan, porphyra, and many more. These polysaccharides found in marine environments can serve as carbon-rich precursors for synthesizing carbon quantum dots (CQDs). Marine polysaccharides have a distinct advantage over other CQD precursors because they contain multiple heteroatoms, including nitrogen (N), sulfur (S), and oxygen (O). The surface of CQDs can be naturally doped, reducing the need for excessive use of chemical reagents and promoting green methods. The present review highlights the processing methods used to synthesize CQDs from marine polysaccharide precursors. These can be classified according to their biological origin as being derived from algae, crustaceans, or fish. CQDs can be synthesized to exhibit exceptional optical properties, including high fluorescence emission, absorbance, quenching, and quantum yield. CQDs’ structural, morphological, and optical properties can be adjusted by utilizing multi-heteroatom precursors. Moreover, owing to their biocompatibility and low toxicity, CQDs obtained from marine polysaccharides have potential applications in various fields, including biomedicine (e.g., drug delivery, bioimaging, and biosensing), photocatalysis, water quality monitoring, and the food industry. Using marine polysaccharides to produce carbon quantum dots (CQDs) enables the transformation of renewable sources into a cutting-edge technological product. This review can provide fundamental insights for the development of novel nanomaterials derived from natural marine sources.