197,327 research outputs found
Superstructure of moraesite: a synchrotron study
No full textMoraesite (Lindberg et al., 1953) is a hydrated berillophosphate with ideal chemical formula Be2(PO4)(OH)·4H2O. Its structure has been known since 1992 (Merlino & Pasero, 1992) and refined in the space group C2/c, a = 8.553(6) Å, b = 12.319(6) Å, c = 7.155(8) Å, β = 97.93(9)°. The main structural feature of moraesite is the presence of large structural cavities occupied by water molecules. The latter are implicated in a complex system of hydrogen bonds where two possible hydrogen bond schemes are equally possible. Few very weak superstructure reflections were observed (Merlino & Pasero, 1992), indicating that the true unit cell of moraesite was probably three times larger, with a b parameter of 36.96 Å and space group symmetry Cc. It was suggested by the authors that the ordering of the hydrogen bond system, concerted with minor adjustments of the structure, could be responsible for the triplication of the b axis. X-ray diffraction data, more recently obtained through synchrotron radiation, confirmed the occurrence of superstructure reflections which were indexed on the basis of an unit cell with tripled b axis. The superstructure of moraesite (a = 8.572(3) Å, b = 36.971(8) Å = 3 x bsub, c = 7.153(2) Å, β = 97.72(1)°, space group Cc) was refined up to R = 0.081 for 1789 unique reflections with Fo > 4sigma(Fo) and 0.0906 for all 2088 data. The structural refinement confirmed that the triplication of the parameter b is due to the ordering of the two possible hydrogen bonding schemes.
1) Lindberg M.L., Pecora W.T. & Barbosa A.L.M. (1953) - Moraesite, a new hydrous beryllium phosphate from Minas Gerais, Brazil. American Mineralogist, 38, 1126-1133.
2) Merlino S. & Pasero M. (1992) - Crystal chemistry of beryllophosphates: The crystal structure of moraesite, Be2(PO4)(OH)·4H2O, Zeitschrift für Kristallographie, 201, 253-262
The Tobermorite-Like Layer in Non-Tobermorite Minerals
No full textThe tobermorite-like layer (TLL) is a characteristic feature in all the structures of the natural and synthetic compounds of the tobermorite group /1/. In those structures eptahedra of calcium cations, characterized by ‘a pyramidal part on one side and a dome part on the other side joining the equatorial oxygen atoms’, form columns through edge sharing; the columns are connected each other, once again through edge sharing, and adjacent columns present the pyramidal apical ligands on opposite sides of the resulting infinite layers. These layers, decorated with wollastonite chains on both sides, build up the ‘complex layers’ which are the basic structural module in all the phases of the tobermorite group (Fig. 1). TLL is a recurrent feature in several natural phases belonging to distinct mineral groups. In the structures of the compounds of the rinkite group the TLL is decorated on both sides by disilicate groups and is accompanied by an infinite ‘octahedral’ layer in building up the structural arrangement. Dovyrenite /2/ and roumaite /3/ are closely related to the minerals of the rinkite group and differ only in the way of decoration of the TLL by the disilicate groups. Fukalite /4/ too presents the TLL, decorated on both sides by four-repeat silicate chains and carbonate groups; tilleyite-type polyhedral layers are also present as distinct modules in building up the structural arrangement. The ubiquitous occurrence of TLL is related to its chemical and structural flexibility: the chemical and geometrical variations of the TLL in the different structures are described and discussed. Key-words: layered silicates, crystal structures, mineralogical crystallography. References /1/ Merlino S., Bonaccorsi E., Armbruster T. (1999): American Mineralogist, 84, 1613–1621. /2/ Kadiyski M., Armbruster T., Galuskin E.V., Pertsev N.N., Zadov A.E., Galuskina I.O., Wrzalik R., Dzierżanowski P., Kislov E.V. (2008): American Mineralogist, 93, 456-462. /3/ Biagioni C., Bonaccorsi E., Merlino S., Parodi G.C., Perchiazzi N., Chevrier V. (2008): Plinius, 34, 211. /4/ Merlino S., Bonaccorsi E., Grabezhev A.I., Zadov A.E., Pertsev N.N., Chukanov N.V. (2009): American Mineralogist, 94, 323–333
MOSANDRITE: STRUCTURAL AND CRYSTAL-CHEMICAL RELATIONSHIPS WITH RINKITE
No full textemical (EPM data), TG–DSC studies and structural investigations indicate that mosandrite presents a particular chemical
composition (low Ca, Na and F contents, high amount of H2O), unit-cell parameters (a 7.398, b 5.595, c 18.662 Å, b 101.37°,
V 757.29 Å3; space-group symmetry P21/c; Z = 2), and a rinkite-type structure characterized by a low occupancy of the M(2) and M(3) sites
Searching for additional functions of fish hemoglobins: evidence of multiple quaternary structures and exogeneous coordination states
No full textAll fish hemoglobins (Hb) show a high auto-oxidation rate, and some fish Hbs are endowed with Root effect (drastic drop of cooperativity at acidic pH). Differently from temperate fish Hbs, at physiological pH Antarctic fish Hbs (AFHbs) in the ferric state show both an aquomet form and two distinct hemichromes within a R / T intermediate quaternary structure (1). Interestingly, AFHbs exhibit a peroxidase activity higher than that observed for mammalian and temperate fish Hbs, thus suggesting that a partial hemichrome state in tetrameric Hbs does not protect them from peroxidation as previously proposed (2). At acidic pH, a combined EPR / x-ray crystallography approach has revealed, only for Root-effect AFHbs, significant amount of pentacoordinated (5C) high-spin Fe(III) species.(3) Furthermore, along the oxidation pathway, a combined x-ray crystallography / Resonance Raman spectroscopy of AFHbs has revealed a hybrid valence state [α(O2)/β(Fe3+, pentacoordinate)].(4) This valence hybrid states prompted us to test a FeSOD activity, that is as low as human Hb. A combined x-ray crystallography / FT-IR study has revealed at least two coordination states of the carbomonoxy form of AFHbs, one corresponding to a His assisted CO binding (band III at 1951 cm-1), and another to a not-His assisted CO binding (band IV at 1968 cm-1). The band IV, typical of both temperate fish (carp and trout) Hbs and AFHbs, assigned to the second CO coordination state, justifies the high auto-oxidation rate of fish Hbs. Furthermore, this novel CO coordination in AFHb occurs within a R-T intermediate quaternary structure. These findings provide an alternative structural explanation of the Root effect, in terms of a three state model .(5) This work was financially supported by PNRA (Italian National Programme for Antarctic Research) 1. Vergara, A., Franzese, M., Merlino, A., Vitagliano, L., di Prisco, G., Verde, C., Lee, H. C., Peisach, J., and Mazzarella, L. (2007) Biophys. J. 93, 2822-2829 2. Feng, L., Zhou, S., Gu, L., Gell, D., Mackay, J., Weiss, M., Gow, A., and Shi, Y. (2005) Nature 435, 697-701 3. Vergara, A., Franzese, M., Merlino, A., Bonomi, G., Verde, C., di Prisco, G., Lee, H., Peisach, J., and Mazzarella, L. . submitted. 4. Vitagliano, L., Vergara, A., Bonomi, G., Merlino, A., Smulevich, G., Howes, B., di Prisco, G., Verde, C., and Mazzarella, L., submitted. 5. Edelstein, S. J. (1996) J. Mol. Biol. 256, 737-74
BIS-HISTIDYL COORDINATION IN TETRAMERIC HEMOGLOBINS: COLD-ADAPTED FISH HEMOGLOBINS VS HUMAN HEMOGLOBIN
No full textAll tetrameric hemoglobins from the Antarctic fish, included Trematomus bernacchii, HbTb, in its ferric state promptly, and distinctively from all the other tetrameric hemoglobins, form a mixture of aquo-met at the α subunits and bis-histidyl adduct (hemichrome) at the β subunits 1,2. The role of the tertiary and quaternary structure in the hemichrome formation in HbTb is still unknown. Here we report the cloning, expression, purification, spectroscopic and computational characterization of the β-chain of HbTb (Tbβ), along with a novel cystallographic determination of the ferric β-chain of human Hb (β4-HbA). As β4-HbA 3,4, Tbβ self assembles to form a β4 homotetramer, but, differently from β4-HbA, Tbβ forms quantitatively a reversible ferric bis-histidyl adduct in the ferric state. Indeed, the herein presented crystal structure of the ferric β4-HbA hosts an aquo-met coordination in all the four independent chains, and not hemichrome. A molecular dynamics study on the isolated β-subunit of HbTb indicates that the ability to form hemichrome is an intrinsic feature of Tbβ chain, probably due to the high intrinsic flexibility associated with its sequence. Differently from HbTb α2β2 heterotetramer 5,6, in the ferrous state Tbβ forms a bis-histidyl adduct (hemochrome). On the bases of these experimental, crystallographic and computational results, a discussion on the effect of quaternary structure on the stability of endogenous ferrous and ferric hexa-coordination is presented.
We acknowledge PNRA and PRIN for financial support
(1) Merlino, A.; Vitagliano, L.; Howes, B.; Verde, C.; di Prisco, G.; Smulevich, G.; Sica, F.; Vergara, A. Biopolymers 2009, 91, 1117.
(2) Vergara, A.; Franzese, M.; Merlino, A.; Vitagliano, L.; di Prisco, G.; Verde, C.; Lee, H. C.; Peisach, J.; Mazzarella, L. Biophys. J. 2007, 93, 2822.
(3) Rachmilewitz, E. A.; Peisach, J.; Blumberg, W. E. J Biol Chem 1971, 246, 3356.
(4) Shikama, K. Chem. Rev. 1998, 98, 1357.
(5) Vergara, A.; Vitagliano, L.; Merlino, A.; Sica, F.; Marino, K.; Verde, C.; di Prisco, G.; Mazzarella, L. J Biol Chem 2010, 285, 32568.
(6) Mazzarella, L.; Vergara, A.; Vitagliano, L.; Merlino, A.; Bonomi, G.; Scala, S.; Verde, C.; di Prisco, G. Proteins 2006, 65, 490
Recipes for Using Olive Oil, ca. 1915
No full textAngelo Merlino immigrated from Italy to Seattle in 1889. Having been in the olive oil business in his homeland, Merlino began importing olive oil in 1900, the first to import the product to Seattle on a large scale. Merlino established the Metropolitan Grocery Co. at 301 Main Street in 1903, where he sold Italian food and products, including his Merlino's Best Brand, or M. B. Brand olive oil, the "Only Oil Awarded Gold Medal at A-Y-P. E."
Over the years, Merlino's sons Ubaldo and Attilio joined their father in the business. Merlino's daughter Annie married Joseph Batali, and their son Armandino founded Seattle's artisan cured meats shop Salumi, still in business today, just around the corner from his grandfather's original store." Armandino Batali's son is the chef, writer and restaurateur Mario Batali.
This booklet contains a collection of recipes using olive oil, "more economical than butter or lard." In addition to recipes for anchovy sauce and sauteed bananas, the cookbook also promises results from the medicinal use of olive oil: "Lubricate your system with pure, high-grade olive oil and half your illnesses will disappear!" The first page features a drawing of a ship captioned "American-Hawaiian Steamship Missourian first trip through Panama Canal with a cargo of Merlino's Best Brand Virgin Olive Oil." Merlino Foods is still in business today in Seattle's SODO neighborhood.1 cookbook: 16 pages; 3.5 x 6 in
Casette d'acqua: aspetti tecnici ed economici
No full textIl consumo dell’acqua in bottiglia in Italia è iniziato negli anni ’70. Da allora tale consumo ha avuto un crescente impulso, accompagnato spesso anche da fenomeni di costume. L’impatto ambientale che deriva dalla filiera delle acque minerali è rilevante: si pensi ad esempio all’uso delle bottiglie di plastica monouso e il consumo di petrolio per fabbricarle, le emissioni legate al trasporto con camion, gli imballaggi di plastica che non sono riciclati.
In questo studio è stata fatta una valutazione delle implicazioni ambientali ed economiche, sia per il cittadino che per l’ente distributore del servizio, legate alla realizzazione e all’uso di punti di erogazione controllata di acqua naturale e frizzante presso le cosiddette casette dell’acqua, ovvero quelle strutture aperte al pubblico, collocate in posizioni strategiche, in grado di fornire ai cittadini punti di prelievo dell’acqua potabile, migliorata dal punto di vista delle caratteristiche organolettiche rispetto a quella direttamente erogata ai rubinetti dal pubblico acquedotto
Identità, immagine e generazione del senso: un modello semiotico per le imprese
No full textLa semiotica studia i processi di significazione, il modo in cui diamo senso alle cose attraverso strutture articolate di significanti (espressioni) e significati (contenuti).
Nelle imprese la semiotica è stata sinora utilizzata nel campo del marketing e della comunicazione, per interpretare o definire il senso di una marca, di un logo, di un messaggio pubblicitario o del packaging di un prodotto.
Diversi studiosi concordano nell’affermare che la semiotica “non ha un oggetto peculiare, ma uno sguardo particolare, un metodo suo proprio” (Bettetini et al. 2005, p. 2): l’articolo presenta un modello, sviluppato dagli autori, nel quale lo “sguardo semiotico” è rivolto all’impresa nel suo insieme.
Analizzando i segni, ovvero i significanti e i significati inscritti nelle organizzazioni, il modello consente di comprendere come si generano l’identità e l’immagine, che possono essere considerate la sintesi del senso delle imprese.
L’utilità del modello consiste nella possibilità di verificare la coerenza (o la non coerenza) dell’identità e dell’immagine tra loro e rispetto agli altri significati e significanti dell’impresa.
Per introdurre il modello l’articolo richiama alcuni concetti di semiotica e ripercorre la letteratura più rilevante in tema di identità e immagine d’impresa.
Successivamente, il caso Aligrup fornisce un esempio di applicazione del modello.
Infine, l’articolo presenta le possibili estensioni e generalizzazioni del modello, focalizzando opportunità, benefici e limiti del suo impiego nelle imprese
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