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Coccolithophores are globally abundant, calcifying microalgae that have profound effects on marine biogeochemical cycles, the climate, and life in the oceans. They are characterized by a cell wall of CaCO3 scales called coccoliths, which may contribute to their ecological success. The intricate morphologies of coccoliths are of interest for biomimetic materials synthesis. Despite the global impact of coccolithophore calcification, we know little about the molecular machinery underpinning coccolithophore biology. Working on the model Emiliania huxleyi, a globally distributed bloom-former, we deploy a range of proteomic strategies to identify coccolithogenesis-related proteins. These analyses are supported by a new genome, with gene models derived from long-read transcriptome sequencing, which revealed many novel proteins specific to the calcifying haptophytes. Our experiments provide insights into proteins involved in various aspects of coccolithogenesis. Our improved genome, complemented with transcriptomic and proteomic data, constitutes a new resource for investigating fundamental aspects of coccolithophore biology.

Despite its importance in many industrial, geological and biological processes, the mechanism of crystallization from supersaturated solutions remains a matter of debate. Recent discoveries show that in many solution systems nanometre-sized structural units are already present before nucleation. Still little is known about the structure and role of these so-called pre-nucleation clusters. Here we present a combination of in situ investigations, which show that for the crystallization of calcium phosphate these nanometre-sized units are in fact calcium triphosphate complexes. Under conditions in which apatite forms from an amorphous calcium phosphate precursor, these complexes aggregate and take up an extra calcium ion to form amorphous calcium phosphate, which is a fractal of Ca(2)(HPO(4))(3)(2-) clusters. The calcium triphosphate complex also forms the basis of the crystal structure of octacalcium phosphate and apatite. Finally, we demonstrate how the existence of these complexes lowers the energy barrier to nucleation and unites classical and non-classical nucleation theories.

We report about the synthesis and characterization of a microporous CoAPO-5 catalyst. Diffuse Reflectance UV-Vis spectroscopy was employed to follow the changes upon oxidation and reduction treatments, showing that a small fraction of Co2+ ions can be reversibly oxidized to Co3+, responsible for the change of colour from blue to green. A large fraction of Co2+ ions are not oxidized in the employed conditions, in agreement with literature reports. FTIR spectroscopy of adsorbed probe molecules was employed to monitor the surface properties of Co ions. NO adsorption resulted in the formation of two stable Co2+(NO)(2) complexes (bands at 1890/1812 cm(-1) and at 1880/1798 cm(-1)), assigned to two unoxidized framework Co2+ with an adjacent oxygen vacancy. A labile Co2+(NO) adduct adsorbing at 1845 cm(-1) could be assigned to Co2+ ions on small extraframework clusters. CO adsorption confirmed the presence of defective Co2+ ions with strong Lewis character that could not be oxidized in the present conditions. Upon reduction, highly dispersed Coo clusters were formed within the microporous channels. In the presence of CO, surface Co-0 atoms were extracted from the clusters to form volatile Coo(CO), (n = 2 or 4) complexes and bridged (Co-0)(n)(CO) species (bands at 2047 and 2008/1990 cm(-1), respectively). These results show that the insertion of heteroatoms in large pore AFI structure is strongly sensitive upon the synthetic conditions and metal loading, that have to be carefully tuned to get the desired catalytically active sites

Proper thermal treatments allowed to modify the number of surface Ca2+ able to coordinate water molecules on the surface of hydroxyapatite (HA) nanoparticles surrounded by an amorphous layer. Despite the consequent significant difference in the first hydration level between untreated and treated HA, the amount of adsorbed BSA, used as a model protein, remained essentially unchanged and the native structure of adsorbed protein was retained (as indicated by mid-IR ATR). Near-IR spectroscopy evidenced that adsorbed proteins should be in direct contact with surface Ca2+ through a displacement of H2O molecules by charged acidic residues. In agreement with a previous study that evidenced the heterogeneity of surface Ca2+ ions in terms of Lewis acidity, it was then proposed that the adsorption of BSA on such nano-HA should be ruled by some feature of the local structure of surface Ca2+ sites, prevailing on the total number of cationic sites exposed and the related features of the first hydration layer

Rhodium nanoparticles supported on gamma-Al2O3 have been prepared by Metal Vapour Synthesis (MVS), using mesitylene solvated Rh atoms as starting material and working in the absence and in the presence of trioctylamine (TOA), as stabilizer. The size and surface features of the metal particles have been studied by Transmission Electron Microscopy (TEM) and by FT-IR spectroscopy of adsorbed carbon monoxide, and they have been compared with those of a commercial Rh/gamma-Al2O3 sample. The results indicated that by MVS technique nanoparticles significantly smaller in size and with a narrower size distribution than those present on the commercial sample were produced. The addition of TOA during the MVS process resulted in a further decrease in the metal particle size. IR spectra of adsorbed CO indicated that metal particles produced via MVS expose at their surface a larger fraction of Rh atoms in low coordination. They can be extracted by CO, forming volatile Rh carbonyls which migrate onto the support, where the metal atoms are oxidised to Rh(l). For Rh particles produced via MVS in the presence of TOA, such low coordinated sites appeared stabilised by adsorbed amine molecules.

Use of zirconia, ceria–zirconia and ceria supports for Ag-based lean deNO x catalysts lowers the temperature range of activity by about 150–200 K with respect to Al 2 O 3 -supported analogues. Ex situ characterisation of the catalysts indicates that this remarkable effect is associated with a role of the support rather than Ag dispersion. The crucial role of the support is further evidenced by suppression of CO formation over these catalysts and by significant support-related differences when SO 2 is added to the feed. The presence of ceria in the formulation results in an initial resistance to the deactivating effect of SO 2 ; while the use of both zirconia and ceria–zirconia facilitates reactivation after sulphur poisoning.

The affinity towards water of a selection of well-defined, nanostructured hydroxyapatite (HA) samples was investigated by H 2 O vapour adsorption microcalorimetry and infrared (IR) spectroscopy. A large hydrophilicity of all investigated materials was confirmed. The surface features of hydrated HA were investigated on the as-synthesized samples pre-treated in mild conditions at T =303 K, whereas dehydrated HA features were characterized on samples activated at T =573 K. The relatively large hydrophilicity of the hydrated surface (−Δ ads H∼100–50 kJ mol −1 ) was due to the interaction of water with the highly polarized H 2 O molecules strongly coordinated to the surface Ca 2+ cations. At the dehydrated surface, exposing coordinatively unsaturated ( cus ) Ca 2+ cations, H 2 O was still molecularly adsorbed but more strongly (−Δ ads H∼120–90 kJ mol −1 ). The use of CO adsorption to quantify the Lewis acidic strength of HA surface sites revealed only a moderate strength of cus Ca 2+ cations, as confirmed by both microcalorimetric and IR spectroscopic measurements and ab initio calculations. This result implies that the large HA/H 2 O interaction energy is due to the interplay between cus Ca 2+ sites and nearby hydrophilic PO 4 groups, not revealed by the CO probe. The lower density of cus Ca 2+ cations at the 573 K activated HA surface with respect to the pristine one did not affect the whole hydrophilicity of the surface, as the polarizing effect of Ca sites is so strong to extend up to the fourth hydrated layer, as confirmed by both high-coverage microcalorimetric and IR spectroscopic data. No specific effects due to the investigated specimen preparation method and/or different morphology were observed.

Alanine, arginine and aspartic acid have been used as co-reagents during the synthesis of a biomimetic calcium-deficient hydroxyapatite (CDHA) for the synergistic coupling of synthesis and functionalization. The surface and bulk characterizations are consistent with a binding model in which the amino acid is preferentially bound to the CDHA nanocrystal surface by its lateral chain group. The ζ-potential measurements show that the amino acid-functionalized CDHA surface charge shifts towards neutral compared to CDHA synthesized in the absence of amino acids. Amino acids bound to the crystal induce crystal growth inhibition predominantly at the Ca-rich surfaces during the initial stages of crystallization. Moreover, high-resolution transmission electron microscopy measurements suggest a model for needle-shaped CDHA nanocrystals formation in the presence of either arginine or aspartic acid based on the oriented aggregation of primary crystallite domains specifically along the c- axis direction and the self-assembly of preformed nanoparticles. The results have significant importance for the control of the shape, morphology and aggregation of the CDHA nanocrystals, while the observed surface modifications are of marked importance for the nature, stability and reactivity of the functionalized surfaces produced.