The Environmental Feasibility of Decentralised Solar Ammonia.

Intense efforts have been devoted to developing green and blue centralised Haber-Bosch processes (gHB and bHB, respectively), but the feasibility of a decentralised and sustainable scheme has yet to be assessed. Here we reveal the conditions under which small-scale systems based on the electrocatalytic reduction of nitrogen (eN2R) powered by photovoltaic energy (NH3-leaf) could become a competitive technology in terms of environmental criteria. To this end, we calculated energy efficiency targets based on solar irradiation atlases to guide research in the incipient eN2R field. Even under this germinal state, the NH3-leaf technology would compete favourably in sunny locations relative to the business-as-usual production scenario. The disclosed sustainability potential of NH3-leaf makes it a strong ally of gHB toward a non-fossil ammonia production.

Environmental and economic potential of decentralised electrocatalytic ammonia synthesis powered by solar energy.

Intense efforts have been devoted to developing green and blue centralised Haber-Bosch processes (gHB and bHB, respectively), but the feasibility of a decentralised and more sustainable scheme has yet to be assessed. Here we reveal the conditions under which small-scale systems (NH3-leaves) based on the electrocatalytic reduction of nitrogen (eN2R) powered by photovoltaic energy could realise a decentralised scheme competitive in terms of environmental and economic criteria. For this purpose, we calculated energy efficiency targets worldwide, providing clear values that may guide research in the incipient eN2R field. Even at this germinal stage, the NH3-leaf technology would compete favourably in sunny locations for CO2-related Earth-system processes and human health relative to the business-as-usual production scenario. Moreover, a modest 8% gain in energy efficiency would already make them outperform the gHB in terms of climate change-related impacts in the sunniest locations. If no CO2 taxation is enforced, the lowest estimated ammonia production cost would be 3 times the industrial standard, with the potential to match it provided a substantial decrease of investment costs and very high selectivity toward ammonia in eN2R are achieved. The disclosed sustainability potential of NH3-leaf makes it a strong ally of gHB toward defossilised ammonia production.

Hybridization of Fossil- and CO2 -Based Routes for Ethylene Production using Renewable Energy.

Carbon capture and utilization (CCU) has recently gained broad interest in the chemical industry. Direct electro- and thermocatalytic technologies are currently the focus of intense research, where the former employs electricity directly to reduce the CO2 molecule, while the latter comprises hydrogenation of CO2 in tandem with electrocatalytic water splitting. So far, it remains unclear which of the two is superior, yet this information is considered critical. Focusing on the platform chemical ethylene, the two CCU routes were compared using state-of-the-art performances with the fossil technology considering different power and CO2 sources. The thermo-route was found to be, at present, economically and environmentally better, yet under the same electrolyzer efficiencies, the electro-route would become superior. CCU routes could substantially improve the carbon footprint of the fossil ethylene (by 236 %) while decreasing at the same time impacts on human health, ecosystem quality, and resources (64, 140, and 80 %, respectively). However, they are economically unattractive even when considering externalities (indirect cost of environmental impacts), that is, 1.7- to 3.9-fold more expensive compared to the current fossil-based analogue. Acknowledging this limitation, the concept of hybridization was applied as a means to smooth the transition towards more sustainable chemicals. Accordingly, it was found that an optimal hybrid plant could produce carbon-neutral (cradle-to-gate) ethylene with a premium of only 30 % over the current market prices by judiciously combining CCU routes with fossil technologies.

Polyamines modulate epithelial-to-mesenchymal transition.

Epithelial-to-mesenchymal transition and mesenchymal-to-epithelial transition are biologic processes responsible for conversion of epithelial cells into a mesenchymal phenotype or viceversa, respectively. They occur during embryo- and foetal-development and, in adult organisms, are involved in wound healing, in the genesis and progression of organ fibrosis as well as in the invasiveness of epithelial cancer cells. The key event of epithelial-to-mesenchymal transition is the loss of E-cadherin expression due to repressor activity of the transcriptional factor Snai1. Intracellular Snai1 levels are controlled through translational and post-translational events such as phosphorylation and de-phosphorylation, potentially modulated by polyamine content. Epithelial MDCK cells exposed to TGF-ß(1) acquired a fibroblastoid phenotype and expressed mesenchymal markers. These changes were emphasized in cells that were also exposed to DFMO in order to decrease the intracellular levels of polyamines. Addition of exogenous polyamines almost completely abolished the combined action of DFMO and TGF-ß(1) and rapidly reverted to epithelial phenotype MDCK cells previously undergone to mesenchymal phenotype. Nuclear extracts of cells treated with DFMO + TGF-ß(1) revealed the presence of Snai1 immunopositive bands in a range of molecular weight between 55 and 72 kDa, with additional positive bands detected at MW greater than 170 kDa. Same bands resulted positive to anti-Sumo 2/3 antibody, suggesting that an intracellular low level of polyamines favours Snai1 nuclear accumulation under the form of polysumoylated proteins.