Indoor gaseous air pollutants determinants in office buildings—The OFFICAIR project

The aim of this study was to identify determinants of aldehyde and volatile organic compound (VOC) indoor air concentrations in a sample of more than 140 office rooms, in the framework of the European OFFICAIR research project. A large field campaign was performed, which included (a) the air sampling of aldehydes and VOCs in 37 newly built or recently retrofitted office buildings across 8 European countries in summer and winter and (b) the collection of information on building and offices’ characteristics using checklists. Linear mixed models for repeated measurements were applied to identify the main factors affecting the measured concentrations of selected indoor air pollutants (IAPs). Several associations between aldehydes and VOCs concentrations and buildings’ structural characteristic or occupants’ activity patterns were identified. The aldehyde and VOC determinants in office buildings include building and furnishing materials, indoor climate characteristics (room temperature and relative humidity), the use of consumer products (eg, cleaning and personal care products, office equipment), as well as the presence of outdoor sources in the proximity of the buildings (ie, vehicular traffic). Results also showed that determinants of indoor air concentrations varied considerably among different type of pollutants.     

Electrical spiking in bacterial biofilms

In nature, biofilms are the most common form of bacterial growth. In biofilms, bacteria display coordinated behaviour to perform specific functions. Here, we investigated electrical signalling as a possible driver in biofilm sociobiology. Using a multi-electrode array system that enables high spatio-temporal resolution, we studied the electrical activity in two biofilm-forming strains and one non-biofilm-forming strain. The action potential rates monitored during biofilm-forming bacterial growth exhibited a one-peak maximum with a long tail, corresponding to the highest biofilm development. This peak was not observed for the non-biofilm-forming strain, demonstrating that the intensity of the electrical activity was not linearly related to the bacterial density, but was instead correlated with biofilm formation. Results obtained indicate that the analysis of the spatio-temporal electrical activity of bacteria during biofilm formation can open a new frontier in the study of the emergence of collective microbial behaviour.     

Post‐polymerization modification by nitroxide radical coupling

Post‐polymerization modification is an attractive approach to extend applications and convert commodity plastics into products with new, desirable and tunable properties. Among the post‐polymerization modification methods, the nitroxide radical coupling (NRC) reaction has been shown to be a convenient and versatile way to graft specific functionalities onto polymer chains and to control the onset and yield of polymer crosslinking during peroxide‐initiated processes. The use of 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) and its derivatives as controllers of scorch in crosslinking and as functionalizers in functionalization reactions is thoroughly described. Examples are also given of graft polymerization from macroalkoxyamines generated by NRC and grafting of nitroxides by irradiation processes. In addition, in this review we attempt to demonstrate the broad applications of the NRC reaction in the preparation of polymers with a multitude of functionalities and elaborate architectures. The examples discussed here concern the use of atom transfer and single electron transfer NRC reactions to design a variety of polymers with asymmetrical structure and the use of the radical crossover reaction, based on the alkoxyamine dynamic covalent bond, to generate reversible polymer structures and switchable functional polymers. © 2018 Society of Chemical Industry     

On the manufacturing of low temperature activated Sr0.9La0.1TiO3-δ-Ce1-xGdxO2-δ anodes for solid oxide fuel cell

Lanthanum doped strontium titanate–gadolinium doped cerium oxide (LST-GDC) anodic layers are sintered in air and further reduced in-situ at low temperature (750 °C) avoiding usually performed pre-reduction treatment at high temperature. The influence of various milling techniques and of powders with different specific surface area, on the microstructures of screen-printed anodes, is investigated. The combination of milling and sonication processes is efficient in reducing aggregation of the anode powders. The anode performance is improved when a planetary milling step is involved in the preparation of the screen printing inks. The use of gadolinium doped cerium oxide with high specific surface area decreases the polarization resistance. The rate of hydrogen oxidation is also enhanced by increasing porosity.     

Effect of heating rate on properties of transparent aluminum oxynitride sintered by spark plasma sintering

High heating rates ranging from 50 to 250°C/min are selected to rapidly sinter transparent aluminum oxynitride (AlON) ceramics by spark plasma sintering (SPS) at 1600°C under 60 MPa using a bimodal AlON powder synthesized by the carbothermal reduction and nitridation method. With 1 minute holding time before cooling, all the specimens show high density and high transparence. The maximum transmittance is up to 74.5%-80.6%, where the maximum transmittance is positively correlated with the heating rate. Further analysis reveals that faster heating rates enable the decrease in the amount of the AlON phase decomposed into the α-Al₂O₃ and AlN phases during heating. These α-Al₂O₃ and AlN phases have to be converted back to AlON at the final stage of sintering, which indicates that a decrease in the amount of the α-Al₂O₃ and AlN phases via the boosted heating leads to the higher transmittance of the AlON ceramics. The high heating rates and short holding duration of the SPS utilized in this study result in the fine grain size of the obtained ceramics (1-6 μm) compared to that of the AlON ceramics fabricated by the conventional sintering method. This effect of high heating rates is confirmed by the coupled densification-grain growth modeling. In turn, the obtained AlON specimens exhibit a Vickers hardness of 15.87-16.62 GPa.     

Bismuth and lead oxides codoped boron phosphate glasses for Faraday rotators

New magneto-optical vitreous materials were obtained by melting-quenching technique comprising wet route raw materials preparation. The glass has the following composition in oxide mol. %: 10 Li₂O, 9 Al₂O₃, 5 ZnO, (35; 20; 50) B₂O₃, (35; 50; 20) P₂O₅, 3 Bi₂O₃, 3 PbO, phosphorus and boron oxide being the vitreous network formers. It was also prepared a similar reference glass composition but without Bi₂O₃ and PbO. Optical and structural characterization by ultraviolet-visible (UV–Vis), Fourier Transform Infrared (FTIR) and Raman Spectroscopy of the bulk glasses showed a transmission over 90%, metaphosphate structure of glass together with Q² boron oxide units and P–O?B bonds. The mechanical parameters, hardness (H), Young's modulus (E) and fracture toughness (K_IC) of boron phosphate glasses, evaluated by micro- and nanoindentation techniques, demonstrated mostly higher values in comparison with those for alumino-phosphate glasses due to mixed boro-phosphate network. Thermal behavior was investigated by Differential Scanning Calorimetry (DSC) putting in evidence the vitreous transition temperature which decreases with about 45 °C when Bi and Pb oxides were added and two crystallization effects. The diamagnetic character of a highly transparent Bi and Pb oxide co-doped boron phosphate glass was confirmed by ellipsometry, and the glass presented high magneto-optical properties at the top of the commercial bulk products.     

Development of a green integrated process for biodiesel esters production: Use of fermented macaúba cake as biocatalyst for macaúba acid oil transesterification

In this study, a new green integrated process for biodiesel ester production was developed, consisting of the enzymatic transesterification of acid oil from macaúba palm tree (Acrocomia aculeata) catalyzed by dry fermented solid (DFS) with lipase activity, which was obtained from solid-state fermentation (SSF) of macaúba cake. Analysis of statistical experimental designs showed that nitrogen supplementation of macaúba cake improved production of lipases displaying esterification capacity by Rhizomucor miehei. The conditions chosen to produce R. miehei DFS were cake supplementation with 2 wt% urea, 60 wt% of initial moisture during 48 h of fermentation at 40°C. DFS showed, by zymography assays, at least one enzyme that was different from those that are present in the commercial lipase of R. miehei. Furthermore, DFS was used in transesterification reactions between macaúba acid oil and alcohol (methanol or ethanol), and the ester content obtained was 92%. This is the first time that this integrated process using low-cost biocatalysts and a low-value oil derived from the processing of the same fruit was used for biodiesel ester production, reducing costs and logistic constraints, and optimizing the raw material utilization.     

Functional bioplastics from food residual: Potentiality and safety issues

Plastic pollution and food waste are two global issues with much in common. Plastic containers were introduced as a practical and easy remedy to improve food preservation and reduce the risk of creating waste, but ironically, to address one problem, another has been made worse. The spread of single-use containers has dramatically increased the amount of plastic that has to be discarded, and the most urgent task is now to find a solution to what has become part of the problem. An innovative way around it consists of promoting the valorization of food residues by turning them into novel materials for packaging. Although the results are promising, the aim of completely replacing plastics with biodegradable materials still seems far from being achieved. This review illustrates the main strategies adopted thus far to produce new bioplastic materials and composites from waste resources and focuses on the pros and cons of the food recovery process to look for the aspects that represent an obstacle to the development of the circular food economy on an industrial scale.