62,346 research outputs found
Application of ammonium phosphate to marble. Investigation of newly-formed calcium phosphates with synchrotron light and high lateral resolution FTIR microspectroscopy
No full textInorganic-mineral treatments exhibit great potentialities for the consolidation of stone materials due to their high compatibility with the substrate. Their reaction mechanism is based on the diffusion, inside weathered stone matrixes, of water soluble precursors that, reacting with the substrate, supply a crystal network able to reconnect detached grain boundaries. The newly-formed crystalline phases are stable and due to their low solubility provide a passivating action toward atmospheric agents even in acid environment. Diammonium hydrogen phosphate [DAP, (NH4)2HPO4] has been recently suggested for the treatment of sedimentary and metamorphic carbonatic decayed stones. The reaction of DAP with calcite of the substrate involves a pseudomorphic replacement and favours the growth of calcium phosphates inside the porosity. Preliminary studies (Matteini et al., 2013; Possenti et al., 2016) show that the reaction at room temperature is non-stoichiometric and induces the formation of hydroxyapatite [HAP, Ca5(PO4)3(OH)] (Ni & Ratner, 2003) and other metastable phases. In this pilot study we characterized the complex assemblages of calcium phosphates formed after DAP treatments on Carrara marble specimens with a multi-analytical approach (scanning electron microscopy, vibrational spectroscopies and powder X-ray diffraction). A set of quarried and thermally decayed samples were treated by poultice and capillarity using DAP solutions at different molarities. Ground-breaking techniques such as X-ray diffraction with synchrotron light in transmitting geometry and high lateral resolution FTIR microspectroscopy were employed to overcome some of the analytical limits of conventional approach, assessing the overall composition of main and trace phases as well as
their arrangement on the substrate. Preliminary findings show the formation of a shell-like layer around the calcite grains, composed by a mixture of crystalline and amorphous calcium phosphates; the formation of specific phases, their morphologies and the relative amount depend on the solution molarity and the treatment duration. Moreover, our data show a correlation between the kind of crystalline phase and its morphology and position within the shell structure.
Matteini, M., Colombo, C., Botticelli, G., Casati, M., Conti, C., Negrotti, R., Possenti, E., Realini M. (2013): Ammonium phosphates
to consolidate carbonatic stone materials: an inorganic-mineral treatment greatly promising. Proceedings of the Built Heritage
2013 Monitoring Conservation Management, 1278-1286.
Ni, M. & Ratner, B.D. (2003): Nacre surface transformation to hydroxyapatite in a phosphate buffer solution. Biomaterials, 24, 4323-
4331.
Possenti, E., Colombo, C., Bersani, D., Bertasa, M., Botteon, A., Conti, C., Lottici, P.P., Conti C. (2016): New insight on the
interaction of diammonium hydrogenphosphate conservation treatment with carbonatic substrates: a multi-analytical approach.
Microchem. J., 127, 79-86
The clinical link between type D personality and diabetes
No full textIntroduction: Type D personality consists of a mixture of high levels of negative affectivity and social inhibition, resulting in a stable tendency to experience negative emotions, by inhibiting the expression of these emotions. We have reanalyzed the clinically relevant studies examining the role of this personality profile in diabetes, by providing a qualitative synthesis of the data. In this regard, the aim of this study is to provide a systematic review by evaluating the clinical link between Type D personality and diabetes.
Method: When focusing on PRISMA guidelines, we have performed a comprehensive research of the literature on PubMed, Scopus, ScienceDirect, ISI Web of Science, PsycINFO, and Google Scholar by using search terms as "distressed personality" OR (i.e., Boolean operator) "Type D personality" combined with the Boolean "AND" operator with "diabetes."
Results: A total of seven research studies were identified and included in the review. Type D was found to be more prevalent in diabetes patients than controls. As regards the specific association with diabetes variables, Type D personality is a significant predictor of both poor medication adherence and unhealthy behaviors, by predicting negative mental health consequences also (i.e., depressed mood, anhedonia, and anxiety).
Conclusion: Our review emphasized for the first time that Type D personality affects clinical factors in patients with diabetes by provoking adverse outcomes. The core implication of the study comprises the clinical relevance to detect, from a clinimetric point of view, Type D personality in diabetes in order to prevent potentially negative clinical outcomes
Partial Equalization for MC–CDMA Systems in Non-Ideally Estimated Correlated Fading
No full textMulticarrier code-division multiple access (MC–CDMA) can support high data rates in next-generation multiuser wireless communication systems. Partial equalization (PE) is a low-complexity technique for combining the signals of subcarriers to improve the achievable performance of MC–CDMA systems in terms of their bit error probability (BEP) and bit error outage (BEO) in comparison with maximal ratio combining, orthogonality restoring combining, and equal-gain combining techniques. We analyze the performance of the multiuser MC–CDMA downlink and derive the optimal PE parameter expression, which minimizes the BEP. Realistic imperfect channel estimation and frequency-domain (FD) block-fading channels are considered. More explicitly, the analytical expression of the optimum PE parameter is derived as a function of the number of subcarriers, number of active users (i.e., the system load), mean signal-to-noise ratio (SNR), and variance of the channel-estimation errors for the aforementioned FD block-fading channel. We show that the choice of the optimal PE technique significantly increases the achievable system load for the given target BEP and BEO
A taxonomic revision of the Siler montanum group (Apiaceae) in Italy and the Balkan Peninsula
No full textAbstract: A morphometric-based taxonomic revision of the Siler montanum group (Apiaceae) from Italy and the Balkan Peninsula was carried out. Multivariate and univariate analyses were performed on 47 morphological characters including seven ratios, and based on the study of 328 dried herbarium specimens. According to our results, the characters employed in the study revealed their suitability as key characters for the examined taxa. A taxonomic treatment was presented and a new diagnostic key to the S. montanum group is also provided for Italy and Balkan Peninsula. Ten taxa were recognized within the group, and among them three new subspecies were described: S. montanum subsp. apuanum, S. montanum subsp. corrasianum and S. montanum subsp. ogliastrinum. Furthermore, three new combinations were proposed: S. zernyi subsp. laeve, S. zernyi subsp. ochridanum and S. montanum subsp. stabianum. Six names were lectotypified: Laserpitium garganicum var. balcanicum, L. garganicum var. laeve, L. garganicum var. scabrum, L. siculum var. stabianum, L. siler var. ovalifolium and Ligusticum garganicum. Occurrences were confirmed for Siler zernyi subsp. zernyi in Greece and S. zernyi subsp. laeve in North Macedonia. Occurrences were excluded for S. montanum subsp. garganicum in Greece and North Macedonia and S. montanum subsp. siculum in C and S Italy. Citation: Conti F., Bartolucci F., Bacchetta G., Pennesi R., Lakušić D. & Niketić M. 2021: A taxonomic revision of the Siler montanum group (Apiaceae) in Italy and the Balkan Peninsula.-Willdenowia 51: 321-347. Version of record first published online on 16 November 2021 ahead of inclusion in December 2021 issue
Pre-consolidation of decayed Angera columns with ammonium phosphate : a pilot study in a Milanese courtyard of XVI Century
No full textAngera stone is a lithotype widely employed in Lombardy (north Italy) for ornamental elements/frameworks of
historical buildings. Owing to decay processes it is affected by detachments, exfoliations, pulverizations with
consequent loss of material. The traditional application of synthetic organic products on the Angera surfaces had a
significant role in the decay processes as well (Colombo et al., 2006). Over the last years, the boundaries of
Conservation Science have been pushed toward the use of inorganic-mineral treatments that are stable, durable, highly
transpirable and more compatible with the stone substrates. Ammonium phosphate [DAP, (NH4)HPO4], one of the most
recent inorganic-mineral treatment, is based on the reaction between a water soluble precursor with carbonatic
substrates; the newly formed crystalline phases are able to restore the lost cohesion of the microstructure. Recent studies
investigated the interactions of DAP solutions with calcite of marbles and limestones (Matteini et al., 2011; Possenti et
al., 2016). To the best of our knowledge, no data are available on the application of DAP to: i) the conservation of
dolostones; ii) the pre-consolidation of decayed stones.
Therefore, in this study we explored the potentialities of DAP treatments as a pre-consolidating agent for white
Angera stone. DAP solutions were vaporized on vertical specimens to avoid mechanical contact with decayed surfaces.
The research evaluated the effects induced by the molarity and the application method (repeated applications, wetted or
dry substrate, comparison with paper poultice) on the surface and the influence of pre-consolidation on the subsequent
consolidation with DAP.
The formation of specific crystalline phases and their diffusion inside the first few microns of the stone matrix were
investigated following a multi-analytical approach (SEM-EDS, Raman and IR spectroscopies, XRD). The research
outcomes supplied outstanding indications for restoration, supporting the application of DAP pre-consolidating
treatments to Angera columns strongly decayed in a Milanese courtyard of XVI Century.
Colombo, C., Conti, C., Realini, M., Sansonetti, A. (2006): Diagnostic studies aimed to conservation works in S. Fedele church
(Milan). Proceedings of HWC Congress (Heritage, Weathering and Conservation), Taylor & Francis Group, 917-922.
Matteini, M., Rescic, S., Fratini, F., Botticelli, G. (2011): Ammonium phosphates as consolidating agents for carbonatic stone
materials used in architecture and cultural heritage: preliminary research. Int. J. Archit. Herit. Conserv. Anal. Restor., 5, 717-736.
Possenti, E., Colombo, C., Bersani, D., Bertasa, M., Botteon, A., Conti, C., Lottici, P.P., Realini, M. (2016): New insight on the
interaction of diammonium hydrogenphosphate conservation treatment with carbonatic substrates: a multi-analytical approach.
Microchem. J., 127, 79-86
GLT-1 promoter activity in astrocytes and neurons of mouse hippocampus and somatic sensory cortex
No full textGLT-1 eGFP BAC reporter transgenic adult mice were used to detect GLT-1 gene expression in individual cells of CA1, CA3 and SI, and eGFP fl uorescence was measured to analyze quantitatively GLT-1 promoter activity in different cells of neocortex and hippocampus. Virtually all GFAP+ astrocytes were eGFP+; we also found that about 80% of neurons in CA3 pyramidal layer, 10-70% of neurons in I-VI layers of SI and rare neurons in all strata of CA1 and in strata oriens and radiatum of CA3 were eGFP+. Analysis of eGFP intensity showed that astrocytes had a higher GLT-1 promoter activity in SI than in CA1 and CA3, and that neurons had the highest levels of GLT-1 promoter activity in CA3 stratum pyramidale and in layer VI of SI. Finally, we observed that the intensity of GLT-1 promoter activity in neurons is 1-20% of that measured in astrocytes. These results showed that in the hippocampus and neocortex GLT-1 promoter activity is observed in astrocytes and neurons, detailed the distribution of GLT-1 expressing neurons, and indicated that GLT-1 promoter activity in both astrocytes and neurons varies in different brain regions. © 2010 de Vivo, Melone, Rothstein and Conti
Calcium phosphates crystallized on Carrara marble after phosphate-based consolidating treatment
No full textDiammonium hydrogen phosphate (DAP, (NH4)2HPO4) solutions have been introduced in the conservation field as a new inorganic-mineral treatments to consolidate or protect decayed carbonatic stone materials of historical monuments [1]. The treatment forms calcium phosphates through a dissolution and re-crystallization reaction, which takes place between hydrogen phosphate groups of the reagent and calcium ions of calcite of the substrate. Calcium phosphates nucleate on calcite grains with a pseudomorphic replacement reaction, and form a crystal network able to restore the lost cohesion of the microstructure. Despite the high number of studies on the crystallization of calcium phosphates and their formation on the surface of carbonatic substrates, only a few studies explored the formation of calcium phosphate phases on marbles treated with DAP and using calcite of the substrate as unique source for calcium ions [2-4]. Previous studies revealed a non-stoichiometric reaction that lead to the formation of a mixture of phases, each one characterized by different Ca/P molar ratio, solubility and stability [4]. In this study, we carry out a non-destructive synchrotron radiation grazing incidence X-ray diffraction (SR-GIXRD) investigation on DAP-treated marbles to determine how the mineralogical composition of the stone substrate affects the crystallization of stable and metastable calcium phosphates. The analyses were performed on Carrara marble specimens treated by capillarity by 0.76 M DAP solutions. Our results indicate that the presence of compositional micro-heterogeneity of Carrara marble favours the formation of specific phases. In general, the composition and the localization of the phases directly depend on the availability of free Ca2+ ions. Dicalcium phosphate dihydrate, a calcium phosphate with a low Ca/P molar ratio, is formed on carbonatic phases with a low Ca content, such as dolomite grains and Mg-containing veins. Octacalcium phosphate (OCP, Ca8(HPO4)2·5H2O) and poorly-crystalline partially-substituted hydroxyapatite (HAP, Ca5(PO4)3OH) are the foremost newly-formed phases when the substrate is mainly composed by calcite.
This study shed light on the potentialities of SR-GIXRD as a powerful non-destructive tool for the diagnostic of Cultural Heritage objects, since it allows investigating the conservation history of stone materials with an in depth evaluation of DAP consolidating processes [5].
[1] M. Matteini, S. Rescic, F. Fratini, G. Botticelli Int. J. Archit. Herit. Conserv. Anal. Restor. 2011, 5, 717.
[2] M. Kamiya, J. Hatta, E. Shimada, Y. Ikuma, M. Yoshimura, H. Monma Mater. Sci. Eng. B 2004, 111, 226.
[3] S. Naidu and G. W. Scherer J. Colloid Interface Sci. 2014, 435, 128.
[4] E. Possenti, C. Colombo, D. Bersani, M. Bertasa, A. Botteon, C. Conti, P. P. Lottici, M. Realini Microchem. J. 2016, 127, 79.
[5] E. Possenti, C. Colombo, C. Conti, L. Gigli, M. Merlini, J. R. Plaisier, M. Realini, G. D. Gatta Appl. Phys. A 2018, 124, 383
Fluid expulsion in accretionary wedges: what can we learn from Miocene seep carbonates (Emilia and Tuscan Apennines, Italy)
No full textSeepage of hydrocarbon-rich fluids is a common process
in accre onary wedges where tectonic thickening and
underpla ng generate pore-fluid overpressures and
induce fluid migra on (Bohrmann et al., 2002; Gill et al.,
2005; Ding et al., 2010; Crutchley et al., 2015; Klaucke et
al., 2015). The migra on and expulsion of methane-rich
fluids promote the precipita on of a variety of authigenic
minerals on the seafloor or within the sediments, i.e.
carbonates (aragonite, calcite, dolomite), sulfides and
sulphates, forming crusts, concre ons and build-ups.
Reduced compounds in the fluids also sustain peculiar
microbial consor a and macrofaunal communi es
(Teichert et al., 2005; Campbell, 2006) (Fig. 1).
It is widely recognized that the most reliable indicators of
fossil cold seeps are the anomalously nega ve carbon
13 isotope composi on of the carbonates, with d C values as
low as -60‰ VPDB (Judd and Hovland, 2009), the peculiar
chemosynthe c bivalves (Lucinidae and Vesicomyidae)
and specific biomarkers (e.g. Taviani, 2014; Peckmann et
al., 2002; Grillenzoni et al., 2017).
In the northern Apennine orogenic belt, several outcrops
of authigenic carbonates tes fy for Miocene seepage
ac vity (Terzi et al., 1994; Dela Pierre et al., 2010; Con et
al., 2017). These carbonates show highly depleted d13C
signatures and host large chemosynthe c bivalve
assemblages (mainly giant lucinids)(Grillenzoni et al.,
2017), thus tes fying a long and complex history of
methane-rich fluid ven ng on the sea floor. Apenninic
carbonate deposits bearing fossil chemosynthe c fauna
have been found in various domains and basin types, from
wedge-top basins to the slope of the accre onary wedge,
and in the inner foredeep (Con and Fontana, 1999;
Argen no et al., 2019a) (Figs 2, 3).
In the following, we summarize and describe the main
features of the Apennine seep carbonates, from field
observa ons to geochemical features
Spectroscopic Investigation of Acid Doped Polybenzimidazole as Electrolyte Membrane for Fuel Cells
No full textOne fundamental component of a fuel cell (FC) is the electrolyte, which separates the electrocatalytic active sites of the two electrode configurations. Acid-doped poly(2,2’-(m-phenylene)-5,5’-bibenzimidazole) (PBI) polymers have been studied as membrane materials for the use in High Temperature Polymer Electrolyte FCs. [1]
In the present study, we report on a FT-Raman investigation of poly(2,5-benzimidazole) (AB-PBI) polymer membranes doped with various concentrations of ortho-phosphoric acid. Characteristic Raman spectra with three diagnostic regions and specific peaks have been studied [2]. Moreover, we present very recent NMR results on the PBI material [3]. The information is of fundamental importance in order to elucidate the role of H3PO4 in conductivity mechanisms in polybenzimidazoles.
[1] J. N. Asensio, E. M. Sánchez and P. Gómez- Romero, Chem. Soc. Rev., 2010, 39, 3210-3239.
[2] F. Conti, A. Majerus, V. Di Noto, C. Korte, W. Lehnert, D. Stolten, Phys. Chem. Chem. Phys., 2012, 14, 10022-10026.
[3] F. Conti, S. Willbold, C. Korte, W. Lehnert, S. Mammi, D. Stolten Polymer, 2012, under review
Seep-carbonates as indicators of global cooling events (Miocene, northern Apennines
No full textRecent studies in dating seep-carbonates suggest that their occurrence is controlled by climatic changes (TEICHERT et alii 2003). KIEL (2009) suggests that this correlation exists from the late Jurassic to Recent, and shows a statistically relevant correlations between the frequency of seep-carbonates in the past 150 Ma and low deep-water temperature and low sea- levels. In the Miocene of the northern Apennines, the abundance and the extent of the seep-carbonates from different tectonic-sedimentary settings, foredeep to satellite basins, provide a rare opportunity to study the tectonic and/or climatic controls on seepage (CONTI & FONTANA, 1999 A detailed stratigraphic and biostratigraphic study of carbonates and enclosing marls indicates that the stratigraphic horizon bearing seep-carbonates lies between the T. cf. T. quinqueloba AE (13.75 Ma) and the P. siakensis A1B (13.32 Ma) encompassing a time interval of about 400.000 years. Since the AE of T. cf. T. quinqueloba approximates the mid- Miocene global cooling event, we infer that the beginning of the seep-carbonate precipitation in the Vicchio Marls seems to be related to this climatic event (Fig. 2). We assume that the ascent and emission of methane-rich fluids may have been triggered by the pressure drop due to the eustatic fall associated with the Mi3b event, estimated in about 60 m (HILGEN et alii, 2009). A drop of the hydraulic pressure on the plumbin
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