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Fusarium endophytes damage cereal crops and contaminate produce with mycotoxins. Those fungi overcome the main chemical defence of host via detoxification by a malonyl‐CoA‐dependent enzyme homologous to xenobiotic metabolizing arylamine N‐acetyltransferase (NAT). In Fusarium verticillioides (teleomorph Gibberella moniliformis, GIBMO), this N‐malonyltransferase activity is attributed to (GIBMO)NAT1, and the fungus has two additional isoenzymes, (GIBMO)NAT3 (N‐acetyltransferase) and (GIBMO)NAT2 (unknown function). We present the crystallographic structure of (GIBMO)NAT1, also modelling other fungal NAT homologues. Monomeric (GIBMO)NAT1 is distinctive, with access to the catalytic core through two "tunnel‐like" entries separated by a "bridge‐like" helix. In the quaternary arrangement, (GIBMO)NAT1 monomers interact in pairs along an extensive interface whereby one entry of each monomer is covered by the N‐terminus of the other monomer. Although monomeric (GIBMO)NAT1 apparently accommodates acetyl‐CoA better than malonyl‐CoA, dimerization changes the active site to allow malonyl‐CoA to reach the catalytic triad (Cys110, His158 and Asp173) via the single uncovered entry, and anchor its terminal carboxyl‐group via hydrogen bonds to Arg109, Asn157 and Thr261. Lacking a terminal carboxyl‐group, acetyl‐CoA cannot form such stabilizing interactions, while longer acyl‐CoAs enter the active site but cannot reach catalytic Cys. Other NAT isoenzymes lack such structural features, with (GIBMO)NAT3 resembling bacterial NATs and (GIBMO)NAT2 adopting a structure intermediate between (GIBMO)NAT1 and (GIBMO)NAT3. Biochemical assays confirmed differential donor substrate preference of (GIBMO)NAT isoenzymes, with phylogenetic analysis demonstrating evolutionary separation. Given the role of (GIBMO)NAT1 in enhancing Fusarium pathogenicity, unravelling the structure and function of this enzyme may benefit research into more targeted strategies for pathogen control. [ABSTRACT FROM AUTHOR]

Highly selective and active electrocatalysts are essential for industrial application of the electrochemical conversion of CO2 into valuable products. The electrochemical cell configuration and the optimisation of its parameters are also of paramount importance to promote the conversion of CO2 and enhance the selectivity and stability of the electrocatalyst. Furthermore, the cell needs to be designed to enable the continuous conversion of CO2 in a flow cell configuration with optimal use of energy resources, to obtain a sustainable CO2-to-formate conversion process. In this work, we present an in-depth, systematic investigation of the crucial parameters for the optimum operation of a flow cell for the conversion of CO2 with a highly scalable Bi-based electrocatalyst at industrially-relevant current densities (j = 100 mA cm-2), achieving high Faradaic efficiency (FEformate > 70%) for a prolonged application time (t = 65 h). By studying and tuning the electrolyte and CO2 feed flow, the membrane configuration, the pH of the electrolyte and the effect of possible contaminants in the CO2 source, we were able to gain important insights into the large-scale application of the Bibased electrocatalyst for the electrochemical reduction of CO2 into formate. [ABSTRACT FROM AUTHOR]

The electrocatalytic reduction of CO2 (CO2RR) in high value products represents a high potential strategy in addressing global climate change. Vulcan XC-72 carbon black is considered to be a promising catalyst support for metals nanoparticles in the CO2RR due to its good electrical properties, high mesoporous distribution and low cost. In this work we reported how the surface chemical modification of Vulcan XC-72 carbon leads to the introduction of oxygenated functionalities with a significant increase of the activity in the electrocatalytic reduction of CO2 to formic acid. The presence of oxygen-containing species results advantageous for the dispersion and anchoring of Sn nanoparticles onto carbon surface increasing the Faradaic selectivity to formic acid up to 80%. [ABSTRACT FROM AUTHOR]

We report on the facile synthesis of SiO2@nitrized‐TiO2 nanocomposite (NST) by calcination of TiO2 xerogel with OctaAmmonium POSS® (N‐POSS; POSS=polyhedral oligomeric silsesquioxanes). The as‐obtained nanoporous mixed oxide is constituted by uniformly distributed SiO2 and nitrized‐TiO2, where the silica component is present in an amorphous state and TiO2 in an anatase/rutile mixed phase (92.1 % vs. 7.9 %, respectively) with very small anatase crystallites (3.7 nm). The TiO2 lattice is nitrized both at interstitial and substitutional positions. NST features a negatively charged surface with a remarkable surface area (406 m2 g−1), endowed with special adsorption capabilities towards cationic dyes. Its photocatalytic behavior was tested by following the degradation of standard aqueous methylene blue and methyl orange solutions under UV and visible light irradiation, according to ISO 10678:2010. For comparison, analogous investigations were carried out on a silica‐free N−TiO2, obtained by using NH4Cl as nitrogen source. [ABSTRACT FROM AUTHOR]

Molecular mechanisms for N2 fixation (solar NH3) and CO2 conversion to C2+ products in enzymatic conversion (nitrogenase), electrocatalysis, metal complexes and plasma catalysis are analyzed and compared. It is evidenced that differently from what is present in thermal and plasma catalysis, the electrocatalytic path requires not only the direct coordination and hydrogenation of undissociated N2 molecules, but it is necessary to realize features present in the nitrogenase mechanism. There is the need for (i) a multi-electron and -proton simultaneous transfer, not as sequential steps, (ii) forming bridging metal hydride species, (iii) generating intermediates stabilized by bridging multiple metal atoms and (iv) the capability of the same sites to be effective both in N2 fixation and in COx reduction to C2+ products. Only iron oxide/hydroxide stabilized at defective sites of nanocarbons was found to have these features. This comparison of the molecular mechanisms in solar NH3 production and CO2 reduction is proposed to be a source of inspiration to develop the next generation electrocatalysts to address the challenging transition to future sustainable energy and chemistry beyond fossil fuels. [ABSTRACT FROM AUTHOR]

The preparation of monodisperse and biocompatible water-soluble superparamagnetic iron oxide nanoparticles (SPIONs) with high sensitivity in Magnetic Resonance Imaging (MRI) represents a challenge for the development of contrast agents. Here we report the synthesis of highly monodisperse citric acid (CA) coated SPIONs with an average diameter of 9 nm and spherical shape, prepared through a suitably optimized coprecipitation method. CA-SPIONs show a high solubility and stability in aqueous medium. Imaging of CA-SPIONs aqueous suspensions was performed in a clinical 1.5-T MRI scanner and different clinical acquisition sequences were exploited. Results show that image contrast can be effectively improved when concentrations of SPIONs lower than 1 ppm are present, and that the echo time is the main parameter influencing the image contrast of SPION-loaded solutions. Moreover, we found that CA-SPIONs show a high value of transverse relaxivity of 128 L mmol-1 s-1 (higher than the commercial contrast agents). Our results are encouraging for the further development of clinical application of SPIONs in MRI, and can represent a starting point for the optimization of clinical imaging exploiting the contrast enhancement of such agents. Namely, it seems possible to achieve an optimal image contrast with low concentration of SPIONs; this could lead to a lower probability of side effects. [ABSTRACT FROM AUTHOR]