130,616 research outputs found
Schede delle opere di Roberto Iras Baldessari, Ugo Vittore Bartolini, Adone Comboni, Lodovico Cavaleri, Beppe Ciardi, Ubaldo Dapino, Angelo Frattini, Alessandro Pandolfi, Leo Spaventa Filippi, Guido Tallone, Aldo Enea Zani delle collezioni d’arte dei Musei Civici di Varese
No full textSchede delle opere di Roberto Iras Baldessari, Ugo Vittore Bartolini, Lodovico Cavaleri, Beppe Ciardi, Adone Comboni, Ubaldo Dapino, Angelo Frattini, Alessandro Pandolfi, Leo Spaventa Filippi, Guido Tallone, Aldo Enea Zani, in D. Cassinelli (a cura di), Musei Civici di Varese: catalogo dei dipinti e delle sculture 1500-1950, Comune di Varese, Varese 2014
Spontaneous Interfacial Fragmentation of Inkjet Printed Oil Droplets and Their electrical characterization
No full textThis work presents the fabrication of femtoliter-scale oil droplets by inkjet printing based on a novel
mechanism for the spontaneous fragmentation at the interface with an immiscible water phase and
the electrical characterization of the resulting immersed “daughter” droplets. [1] In particular,
picoliter-scale fluorinated oil droplets impact on surfactant laden water phase at moderately high
Weber number (101), and are subjected to spreading and capillary instabilities at the water/air interface which ultimately lead to rupture in smaller sized droplets, according to reported models for macroscale droplets systems - [2] the emerging fragmentation results in “daughter” droplets having volumes of about 10-30 % with respect to the initial droplet volume. Remarkably, the picoliter scale downscaling leads to a novel surfactant-driven fragmentation due to the low Bond number (around 10-4-10-5), meaning that droplet immersion is dependent on surface tension forces and not on gravitational forces. In fact, the non-ionic Polyoxyethylene (20) sorbitan monolaurate was observed to permit the droplet immersion in the water phase only if spiked in the water phase at concentrations equal or higher than its critical micellar concentration (i.e. around 0.003% v/v). The resulting oil “daughter” droplets are characterized by a chip with integrated microelectrodes, permitting to extract number, velocities and diameter distribution (peaked at about 3 m) employing electrical impedance
measurements. In accordance with reported models, the electrical characterizations show that the
droplets have volumes in the femtoliter scale and are subjected to inertial focusing. [3] This work can
be considered an important advancement for understanding the effects of downscaling on
fragmentation phenomena at immiscible interfaces, leading to a knowledge platform for a tailored oil
droplets fabrication applicable for drug encapsulation, pharmaceutic preparations, and thin-film
wrapping around droplets. [4]
Bibliography
1. D. Spencer, F. Caselli, P. Bisegna and H. Morgan., Lab Chip, 2016, 16, 2467.
2. H. Lhuissier, C. Sun, A. Prosperetti, and D. Lohse, Phys. Rev. Lett., 2013, 110,
3. G. Arrabito, V. Errico, A. De Ninno, F. Cavaleri, V. Ferrara, B. Pignataro, and F.Caselli, Langmuir,
2019, 35, 4936.
4. D. Kumar, J. D. Paulsen, T. P. Russell, N. Menon, Science, 2018, 359, 775
Interfacial fragmentation and electrical characterization of inkjet printed dil droplets
No full textThis work presents a novel mechanism for the spontaneous fragmentation of picoliter-scale oil droplets at the interface with an immiscible water phase, and the electrical characterization of the resulting immersed “daughter” droplets by an electrical impedance chip (see Figure). [1] In particular, picoliter-scale fluorinated oil droplets are produced by inkjet printing at velocity higher than 5 m/s. Upon impact on the surfactant laden water phase at moderately high Weber number , i.e. around 10, the oil droplet is subjected to spreading and capillary instabilities at the water/air interface. These ultimately lead to its rupture in smaller sized droplets, according to
the reported models for macroscale droplets, [2] for which fragmentation results in “daughter” droplets with volumes reduced of about 10-30 %. Remarkably, the picoliter scale downscaling leads to a novel surfactant-driven fragmentation due to the low Bond number - around 10^(-4) -10^(-5), the droplet immersion mainly depending on surface tension forces. Indeed, the non-ionic Polyoxyethylene (20) sorbitan monolaurate was observed to permit the droplet immersion in the water phase only if spiked in the water phase at
concentrations equal or higher than its critical micellar concentration. The emerging “daughter” droplets are characterized by a microfluidic chip with integrated microelectrodes, permitting to extract number, velocities and diameter distribution (about 3 μm) by means of electrical impedance measurements. The electrical characterizations show that the droplets have volumes in the femtoliter scale and are not subjected to inertial focusing, owing to their small size. [3] This work can be considered an important advancement for understanding the effects of downscaling on fragmentation phenomena at immiscible interfaces, leading to a knowledge platform for a tailored oil droplets fabrication applicable for drug encapsulation, pharmaceutic preparations, and thin-film wrapping around droplets.[4]
Bibliography
1. D. Spencer, F. Caselli, P. Bisegna and H. Morgan., Lab Chip, 2016, 16, 2467.
2. H. Lhuissier, C. Sun, A. Prosperetti, and D. Lohse, Phys. Rev. Lett., 2013, 110,
3. G. Arrabito, V. Errico, A. De Ninno, F. Cavaleri, V. Ferrara, B. Pignataro, and F.Caselli, Langmuir, 2019, 35, 4936.
4. D. Kumar, J. D. Paulsen, T. P. Russell, N. Menon, Science, 2018, 359, 775
On a class of poly-context-free groups generated by automata
No full textThis paper deals with graph automaton groups associated with trees and some generalizations. We start by showing some algebraic properties of tree automaton groups. Then we characterize the associated semigroup, proving that it is isomorphic to the partially commutative monoid associated with the complement of the line graph of the defining tree. After that, we generalize these groups by introducing the quite broad class of reducible automaton groups, which lies in the class of contracting automaton groups without singular points. We give a general structure theorem that shows that all reducible automaton groups are direct limits of poly-context -free groups which are virtually subgroups of the direct product of free groups; notice that this result partially supports a conjecture by T. Brough. Moreover, we prove that tree automaton groups with at least two generators are not finitely presented and they are amenable groups, which are direct limit of non-amenable groups
IL SISTEMA AD INTARSI CERAMICI PREFORMATI CERANA COME METODICA SOSTITUTIVA ALLE OTTURAZIONI IN AMALGAMA.
No full textGraph automaton groups
No full textIn this paper we define a way to get a bounded invertible automaton starting from a finite graph. It turns out that the corresponding automaton group is regular weakly branch over its commutator subgroup, contains a free semigroup on two elements and is amenable of exponential growth. We also highlight a connection between our construction and the right-angled Artin groups. We then study the Schreier graphs associated with the self-similar action of these automaton groups on the regular rooted tree. We explicitly determine their diameter and their automorphism group in the case where the initial graph is a path. Moreover, we show that the case of cycles gives rise to Schreier graphs whose automorphism group is isomorphic to the dihedral group. It is remarkable that our construction recovers some classical examples of automaton groups like the Adding machine and the Tangled odometer. Mathematics Subject Classification (2020): 20F65, 20F05, 20E08, 05C10, 05C25
STABILIZZAZIONE DELLA PROTESI MEDIANTE ANCORAGGIO CON MINI IMPIANTI IN PAZIENTI CON EDENTULIA TOTALE INFERIORE E ATROFIA DEL PROCESSO ALVEOLARE
No full textA semi-empirical stress-strain model for equivalent strut fiber-section modeling of infilled frames
No full textInfill-frame interaction is commonly modeled by means of equivalent strut macro-models. The main difficulty in using this phenomenological approach is to properly calibrate a force-displacement curve for the struts, as this depends not only on the geometrical and mechanical properties, but more specifically on the different potential damage mechanisms which may occur for the infill-frame system subject to lateral forces. If fiber-section elements are used as diagonal struts, the force-displacement curve is substituted by a stress-strain law. In both cases, the attribution of the inelastic law of the struts, based on a mechanical approaches, is not valid in general, as mechanical approaches are referred to specified hypotheses on the collapse modalities, which are really difficult to predict a priori. Based on this, the paper proposes a new concrete-type stress-strain relationship to be used with fiber-section elements and calibrated using a semi-empirical approach rather than a mechanical one. The proposed stress-strain model depends on four parameters. Experimental data and additional numerical simulations are used to derive semi-empirical correlations associating geometrical and mechanical properties of the frame-infill system with the aforementioned parameters. Analytical correlations of the best fitting equations are provided as tools for direct identification. Validation tests are finally carried out with experimental results different from those used to build the correlations
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