Contributi italiani alla nascita della Petrografia

Verso la fine del XVIII e nei primi decenni del XIX secolo alcuni esperti italiani nella prospezione e sfruttamento minerario ed interessati nelle Scienze della Terra, G. Arduino, G. Marzari Pencati, G. Brocchi, e S. Breislak, hanno correttamente riconosciuto in base ad osservazioni sul campo la natura che oggi definiremmo magmatica di corpi sia intrusivi che vulcanici all'interno di sequenze sedimentarie, in contrasto con quanto previsto dalle teorie nettunistiche di Werner, allora dominanti. Ma anche celebrati studiosi di Storia Naturale, come L. Spallanzani e G. Gioeni hanno dato un importante contributo alle ricerche sulle rocce, ed al termine del periodo è da ricordare anche C. Gemmellaro, successore di Gioeni. La Petrografia si stava allora sviluppando, nella cornice della Storia Naturale, come disciplina autonoma dalla Mineralogia e dalla Geologia quando fu possibile classificare le rocce, già suddivise da Werner in gruppi fondati su criteri sistematici embrionalmente petrografici, sulla base dei primi fondamentali lavori di Cordier (1816), von Leonhard (1823) e Brongniart (1827), che hanno introdotto una tassonomia delle rocce, ancora affetta da inconsistenze ed ingenuità, in base alla loro composizione ed origine

Separation of Ho3+ in Static Magnetic Field

Abstract The rare earths elements (REE) belong to the group of critical metals and they are achieving more and more interest due to their special properties. However, there occur some problems connected with their production. The most difficult phase is separation of REE. It includes a necessity to intensify currently applied processes and looking for new solutions. The present work introduces an idea to use differences in physical properties of the REE ions to get them separated. In the experimental part of the work some efforts were undertaken to analyse results presenting changes of holmium ions concentration under an influence of the magnetic field gradient. There was determined the gradient of magnetic field and concentration of Ho3+ ions depending on initial concentration of the solution and time. A simulation of changing the concentration of holmium ions in the solution under an influence of the magnetic field gradient was performed to compare the mathematical model with the obtained results

Statistical properties and morphology of a 2D gel network at the air/water interface

We report here a detailed characterization of the steps leading to the formation of a bidimensional gel at the air/water interface. The 2D geometry is peculiar in that it allows a continuous and controlled variation of the density of the system over a wide range. The evolution of the statistical properties of the structured network, as a function of the externally controlled density, is related to the corresponding evolution of the mechanical properties. We identified three steps in the gel formation: a first step occurs in the incubation time, in which the individual nm-sized gold nanoparticle aggregate to form quasi 1D structures of typical length of a few microns. The second step occurs in the first stages of the compression, with the growth of the branched structure, finally yielding to the onset of the infinite percolative cluster, which is related to the building of the mechanical elastic modulus. The final step identifies with the homogenization and regularization of the distribution of holes sizes, which relates to the further increase of the elastic modulus upon compression. We speculate that this study should help in the formulation of gels with desired characteristics, such as increased mechanical strength, or increased mobilit

Primary stability of a press-fit cup in combination with impaction grafting in an acetabular defect model

The objectives of this study were to (a) assess primary stability of a press-fit cup in a simplified acetabular defect model, filled with compacted cancellous bone chips, and (b) to compare the results with primary stability of a press-fit cup combined with two different types of bone graft substitute in the same defect model. A previously developed acetabular test model made of polyurethane foam was used, in which a mainly medial contained defect was implemented. Three test groups (N = 6 each) were prepared: Cancellous bone chips (bone chips), tricalciumphosphate tetrapods + collagen matrix (tetrapods + coll), bioactive glass S53P4 + polyethylene glycol-glycerol matrix (b.a.glass + PEG). Each material was compacted into the acetabulum and a press-fit cup was implanted. The specimens were loaded dynamically in the direction of the maximum resultant force during level walking. Relative motion between cup and test model was assessed with an optical measurement system. At the last load step (3000 N), inducible displacement was highest for bone chips with median [25th percentile; 75th percentile] value of 113 [110; 114] µm and lowest for b.a.glass + PEG with 91 [89; 93] µm. Migration at this load step was highest for b.a.glass + PEG with 868 [845; 936] µm and lowest for tetrapods + coll with 491 [487; 497] µm. The results show a comparable behavior under load of tetrapods + coll and bone chips and suggest that tetrapods + coll could be an attractive alternative to bone chips. However, so far, this was found for one specific defect type and primary stability should be further investigated in additional/more severe defects

Apoptosis and cell proliferation in porcine placental vascularization

The placenta is a highly vascularized organ, indispensable tothe transfer of nutrients to the growing fetuses. During gestation, there exists an expansion of the placental vascular network through active angiogenesis. The aim of this research was to study cell proliferation and apoptosis through high resolution light microscopy (HRLM) and transmission electron microscopy (TEM) ultrastructure, immunohistochemistry for Ki67and caspase-3, determination of placental vascular area,and TUNEL assay. Crossbred sows placental tissues from approximately 30 ± 2(n =5), 40 ± 2(n =5), 60 ± 2 (n =5), 80 ± 2(n =5), 90 ± 2(n =5) and 114 ± 2(n =5) days of gestation were used. The evaluation of cell proliferation showed the highest%Ki67 values on days 30 ± 2 and 80 ± 2 of pregnancy. Caspase-3 expressed the highest value on day 30 ± 2, while the highest apoptotic indexes were found on days30 ± 2 and 90 ± 2. The placental vascular area was higher on day 80 ± 2 of pregnancy. According to our results, an active vascular cell remodeling by a caspase-3 dependent apoptosis seems to be present in early pregnancy. The increase in the vascular area on day 80 ± 2 would be the result of the intense vascular cell proliferation detected with Ki67. Further studies are needed to understand the complex processes of angiogenesis, cell proliferation and apoptosis that interact in the placenta during porcine gestation.Facultad de Ciencias Veterinaria

Multiscale Bone Remodelling with Spatial P Systems

Many biological phenomena are inherently multiscale, i.e. they are characterized by interactions involving different spatial and temporal scales simultaneously. Though several approaches have been proposed to provide "multilayer" models, only Complex Automata, derived from Cellular Automata, naturally embed spatial information and realize multiscaling with well-established inter-scale integration schemas. Spatial P systems, a variant of P systems in which a more geometric concept of space has been added, have several characteristics in common with Cellular Automata. We propose such a formalism as a basis to rephrase the Complex Automata multiscaling approach and, in this perspective, provide a 2-scale Spatial P system describing bone remodelling. The proposed model not only results to be highly faithful and expressive in a multiscale scenario, but also highlights the need of a deep and formal expressiveness study involving Complex Automata, Spatial P systems and other promising multiscale approaches, such as our shape-based one already resulted to be highly faithful.Comment: In Proceedings MeCBIC 2010, arXiv:1011.005

Evidence for distinct polymer chain orientations in KC60 and RbC60

The KC60 and RbC60 polymer phases exhibit contrasting electronic properties while powder diffraction studies have revealed no definite structural difference. We have performed single crystal X-ray diffraction and diffuse scattering studies of these compounds. It is found that KC60 and RbC60 possess different chain orientations about their axes, which are described by distinct space groups Pmnn and I2/m, respectively. Such a structural difference will be of great importance to a complete understanding of the physical properties.Comment: To be published in Phys. Rev. Let

Identification of phenolic constituents of cytisus multiflorus

The phenolic composition of the ethanolic extract obtained from the flowers of the medicinal plant Cytisus multiflorus has been elucidated by high performance liquid chromatography, electrospray mass spectrometry and nuclear magnetic resonance analysis. The extract was mainly composed of flavones, including the common chrysin, orientin, luteolin-5-O-glucoside, luteolin-7-O-glucoside, apigenin and apigenin-7-O-glucoside, which appeared as minor components. The major flavone in the extract was chrysin-7-O-B-D-glucopyranoside, and it also contained moderate amounts of a dihydroxyflavone isomer of chrysin, as well as of 2''-O-pentosyl-6-C-hexosyl-luteolin, 2''-O-pentosyl-8-C-hexosyl-luteolin and 6''- O-(3-hydroxy-3-methylglutaroyl)-2''-O-pentosyl-C-hexosyl-apigenin, which are not commonly found in the Fabaceae family. Other novel phenolic compounds found in the ethanolic extract of C. multiflorus comprised the flavones 2''-O-pentosyl-6-C-hexosyl-apigenin, 2''-O-pentosyl-8-C-hexosyl-apigenin and 6''-O-(3-hydroxy-3-methylglutaroyl)-200-O-pentosyl-C-hexosyl-luteolin. The assessment of the biological activities of the main compounds of this extract are now keen, in order to determine their relevance in the beneficial properties of the plant