Changes induced by UV radiation in the presence of sodium benzoate in films formulated with polyvinyl alcohol and carboxymethyl cellulose

This work was focused on: i) developing single and blend films based on carboxymethyl cellulose (CMC) and polyvinyl alcohol (PVOH) studying their properties, ii) analyzing the interactions between CMC and PVOH and their modifications UV-induced in the presence of sodium benzoate (SB), and iii) evaluating the antimicrobial capacity of blend films containing SB with and without UV treatment. Once the blend films with SB were exposed to UV radiation, they exhibited lower moisture content as well as a greater elongation at break and rougher surfaces compared to those without treatment. Considering oxygen barrier properties, the low values obtained would allow their application as packaging with selective oxygen permeability. Moreover, the characteristics of the amorphous phase of the matrix prevailed with a rearrangement of the structure of the polymer chain, causing a decrease of the crystallinity degree. These results were supported by X-rays and DSC analysis. FT-IR spectra reflected some degree of polymer–polymer interaction at a molecular level in the amorphous regions. The incorporation of sodium benzoate combined with UV treatment in blend films was positive from the microbial point of view because of the growth inhibition of a wide spectrum of microorganisms. From a physicochemical perspective, the UV treatment of films also changed their morphology rendering them more insoluble in water, turning the functionalized blend films into a potential material to be applied as food packaging.Fil: Villarruel, S.. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; ArgentinaFil: Giannuzzi, Leda. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; ArgentinaFil: Rivero, Sandra G. M.. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; ArgentinaFil: Pinotti, Adriana Noemi. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentin

Seeking to enhance the bioenergy of municipal sludge: Effect of alkali pre-treatment and soluble organic matter supplementation

The aim of this research is to enhance the mesophilic anaerobic digestion of municipal sludge from Cadiz-San Fernando (Spain) wastewater treatment plant at 20 days hydraulic retention time (HRT). Two different strategies were tested to improve the process: co-digestion with the addition of soluble organic matter (1% v/v); and alkali sludge pre-treatment (NaOH) prior to co-digestion with glycerine (1% v/v). Methane production (MP) was substantially enhanced (from 0.36 ± 0.09 L CH4 l/d to 0.85 ± 0.16 L CH4 l/d), as was specific methane production (SMP) (from 0.20 ± 0.05 L CH4/g VS to 0.49 ± 0.09 L CH4/g VS) when glycerine was added. The addition of glycerine does not seem to affect sludge stability, the quality of the effluent in terms of pH and organic matter content, i.e. volatile fatty acids (VFA), soluble organic matter and total volatile solid, or process stability (VFA/Alkalinity ratio < 0.4). Alkali pre-treatment prior to co-digestion resulted in a high increase in soluble organic loading rates (more than 20%) and acidification yield (more than 50%). At 20 days HRT, however, it led to overload of the system and total destabilization of the mesophilic anaerobic co-digestion of sewage sludge and glycerine

Mesophilic anaerobic co-digestion of sewage sludge with glycerine: Effect of solids retention time

The main objective of this paper is to examine the effect of the increase in organic loading rates (OLRs), by reducing the solids retention time (SRT) from 20 d to 5 d, in single-phase mesophilic anaerobic co-digestion of sewage sludge with glycerine (1% v/v). It was experimentally confirmed that anaerobic co-digestion of these biowastes under steady-state conditions can achieve an 85 ± 5% reduction in volatile fatty acids (VFA) at SRTs of between 20 and 9 d, with a methane production yield of around 0.8 l CH4/l/d. Decreases in the SRT not only allow the sludge stability and biogas production to be maintained, but also lead to an increase in the waste that could be treated and lower operating costs. Therefore, mesophilic anaerobic co-digestion of sewage sludge and glycerin at a SRT lower than 20 d is possible and preferable due to being more economical and environmentally friendl

Short-Term Space Occupancy and Conjunction Filter

Conjunction analysis for resident space objects (RSOs) requires estimating the range of altitudes that each object can cross, i.e. its space occupancy, throughout a screening time of, typically, a few days. The work proposes an analytical method to evaluate the space occupancy of an RSO for a time horizon of generic duration in a zonal problem model. The method, which allows one to compute the maximum and minimum occupied orbit radii by solving a quartic equation, is employed as a basis for the implementation of a new conjunction filter with a considerable performance improvement compared to the classical apogee-perigee filter. The effectiveness of the newly proposed filter is assessed in a low-Earth orbit scenario using a high-fidelity perturbation model and for a wide range of orbits and conjunction geometries. Finally, the space occupancy evaluation method is employed as a quick and effective tool to assess the degree of radial overlap of RSOs in low-earth orbit and its evolution in the last decade.Comment: preprint submitted to AIAA Journal of Guidance, Control and Dynamic

Educommunication and archaeological heritage in Italy and Spain: an analysis of institutions’ use of Twitter, sustainability, and citizen participation

Improving heritage educommunication on the web 2.0 is key to reaching certain sustainable development goals focused on educational quality and citizen participation. Although numerous partial studies have already been conducted, to date neither assessment tools nor detailed studies are available regarding the quality of educommunicative initiatives. Spain and Italy’s archaeological heritage museums have a consolidated track record on Twitter, which has been bolstered by museum closures due to COVID-19 and has resulted in a significant change to their educommunicative policies. The present article aims to analyze educommunicative actions undertaken on Twitter at Italian archaeological museums, compare their strategies with a previous study on Spanish institutions, and analyze to what degree the sustainability of heritage, citizen participation, learning opportunities, and universal access are being promoted. This mixed method analysis was carried out through the implementation of a web 2.0 heritage educommunication analysis tool focused on three key factors: educational procedure, R-elational interactions, and the prevailing learning paradigm, as well as a content analysis of the variables that comprise them. The key findings suggest that neither country is close to achieving a quality educommunicative strategy. Italian archaeological heritage institutions use Twitter simply as an advertising platform. Despite being a social media platform, participative initiatives are scarcely promoted, although heritage sustainability is promoted through raising awareness of conservation and appreciation. Spanish institutions, however, demonstrated the opposite pattern of use