113,287 research outputs found
Erratum and addendum to "Two-point b.v.p. for multivalued equations with weakly regular r.h.s."
No full textIn this paper, we define a topological index for compact multivalued maps in convex metrizable subsets of a locally convex topological vector space in order to correct the proofs of Theorems 4.1 and 4.2 in Benedetti-Malaguti-Taddei, Nonlinear Anal. 74 (2011) 3657–3670
Correction: Pavlačková, M.; Taddei, V. Mild Solutions of Second-Order Semilinear Impulsive Differential Inclusions in Banach Spaces. Mathematics 2022, 10, 672
No full textThe authors would like to correct parts of Step (b) and Step (d) in Theorem 1 in [...
It’s all about the surface! Vibrational spectroscopy applied to the study of biomimetic surfaces in Tissue Engineering
No full textTissue Engineering is a multidisciplinary field aimed at the creation of biological substitutes that restore and maintain the biological function of a damaged tissue. The key of the success of these biomedical devices lies into surface interactions with living tissues, therefore a common strategy is to create biomimetic surfaces that helps cells to colonize the biomaterial, leading to tissue healing.
Vibrational spectroscopy, in particular Raman, apart from being mainly surface and non-destructive technique, is extremely sensitive to changes in structure and molecular interactions, thus its use in investigating biomimetic devices is increasing.
In particular, we have recently used vibrational spectroscopies to investigate different biomimetic materials and to test some of their proprieties:
- self-assembling peptides adsorbed on titanium surfaces for bone implants [1], analyzed before and after attack from free radicals (obtained by gamma-radiolysis and mimicking inflammation processes) [2], with the aim to evaluate their capability in resisting to oxidative stress;
- composite (ceramic-polymer, polymer-polymer) bioresorbable biomaterials [3, 4];
- hydroxyapatite nanomaterials functionalized with proteins to increase biocompatibility [5-7].
[1] M. Di Foggia, P. Taddei, A. Torreggiani, M. Dettin, A. Tinti, J. Raman Spectrosc. 42 (2011) 276-285.
[2] M. Di Foggia, A. Torreggiani, P. Taddei, M. Dettin, A. Tinti, J. Raman Spectrosc. 44 (2013) 1446-1450.
[3] V. Guarino, F. Causa, P. Taddei, M. Di Foggia, G. Ciapetti, D. Martini, C. Fagnano, N. Baldini, L. Ambrosio, Biomaterials 29 (2008) 3662-3670.
[4] V. Guarino, P. Taddei, M. Di Foggia, C. Fagnano, G. Ciapetti, L. Ambrosio, Tissue Eng. A 15 (2009) 3655-3668.
[5] M. Iafisco, B. Palazzo, G. Falini, M. Di Foggia, S. Bonora, S. Nicolis, L. Casella, N. Roveri, Langmuir 24 (2008) 4924-4930.
[6] M. Iafisco, M. Di Foggia, S. Bonora, M. Prat, N. Roveri, Dalton Trans. 40 (2011) 820-827.
[7] M. Iafisco, E. Varoni, M. Di Foggia, S. Pietronave, M. Fini, N. Roveri, L. Rimondini, M. Prat, Colloids Surf.s B 90 (2012) 1-7
Bound Sets Approach to Impulsive Floquet Problems for Vector Second-Order Differential Inclusions
No full textIn this paper, the existence and the localization of a solution of an impulsive vector multivalued second-order Floquet boundary value problem are investigated. The method used in the paper is based on the combination of a fixed point index technique with bound sets approach. At first, problems with upper-Carathéodory right-hand sides are investigated and it is shown afterwards how can the conditions be simplified in more regular case of upper semi-continuous right hand side. In this more regular case, the conditions ensuring the existence and the localization of a solution are put directly on the boundary of the considered bound set. This strict localization of the sufficient conditions is very significant since it allows some solutions to escape from the set of candidate solutions. In both cases, the C1-bounding functions with locally Lipschitzian gradients are considered at first and it is shown afterwards how the conditions change in case of C2-bounding functions. The paper concludes with an application of obtained results to Liénard-type equations and inclusions and the comparisons of our conclusions with the few results related to impulsive periodic and antiperiodic Liénard equations are obtained
The damped vibrating string equation on the positive half-line
No full textIn this paper, the existence of a solution to the problem describing the small vertical vibration of an elastic string on the positive half-line is investigated in the case when both viscous and material damping coefficients are present. The result is obtained by transforming the original partial differential equation into an appropriate abstract second-order ordinary differential equation in a suitable infinite dimensional space. The abstract problem is then studied using the combination of the Kakutani fixed point theorem together with the approximation solvability method and the weak topology. The applied procedure enables obtaining the existence result also for problems depending on the first derivative, without any strict compactness assumptions put on the right-hand side and on the fundamental system generated by the linear term. The paper ends by applying the obtained result to the studied mathematical model describing the small vertical vibration of an elastic string with a nonlinear Balakrishnan–Taylor-type damping term
Global exponential stability of the periodic solution of a delayed neural network with discontinuous activations
No full textWe study the stability of a delayed Hopfield neural network with periodic coefficients and inputs and an arbitrary and constant delay. We consider non-decreasing activation functions which may also have jump discontinuities in order to model the ideal situation where the gain of the neuron amplifiers is very high and tends to infinity. In particular, we drop the assumption of Lipschitz continuity on the activation functions, which is usually required in most of the papers. Under suitable assumptions on the interconnection matrices, we prove that the delayed neural network has a unique periodic solution which is globally exponentially stable independently of the size of the delay. The assumptions we exploit concern the theory of M-matrices and are easy to check. Due to the possible discontinuities of the activation functions, the convergence of the output of the neural network is also studied by a suitable notion of limit. The existence, uniqueness and continuability of the solution of suitable initial value problems are proved
Mild Solutions of Second-Order Semilinear Impulsive Differential Inclusions in Banach Spaces
No full textIn this paper, the existence of a mild solution to the Cauchy problem for impulsive semilinear second-order differential inclusion in a Banach space is investigated in the case when the nonlinear term also depends on the first derivative. This purpose is achieved by combining the Kakutani fixed point theorem with the approximation solvability method and the weak topology. This combination enables obtaining the result under easily verifiable and not restrictive conditions on the impulsive terms, the cosine family generated by the linear operator and the right-hand side while avoiding any requirement for compactness. Firstly, the problems without impulses are investigated, and then their solutions are glued together to construct the solution to the impulsive problem step by step. The paper concludes with an application of the obtained results to the generalized telegraph equation with a Balakrishnan–Taylor-type damping term
Aree di conflitto e lavoro minorile: una sfida per il sistema educativo palestinese
No full textThe article aims to tackle the relationship between the phenomenon of child work and the Palestinian
educational reality starting from a first explorative investigation carried out within pilot
schools involved in an international cooperation project, funded by the Italian Agency For Development
Cooperation. The schools involved have a very high percentage of working children. This
initial methodological phase of the survey has foreseen the integrated use of an “Index for inclusion
and empowerment” questionnaire (inspired by the original Index for Inclusion), designed in the
framework of the cooperation project by a group of researchers of the Department of Education
Studies of Bologna University, and the collection of life stories of working children. The interpretation
of the first results, on the basis of the theoretical foundations of the Index instrument, of
the main approaches to the phenomenon of child work in the international debate and the challenges
posed by the context characterized by the dimension of the conflict, underlines the need
to continue the research process on the fundamental characteristics of a Palestinian school able
to include working children through the introduction of cultural, organizational and didactical innovations
New Hybrid Zirconium Aminophosphonates Containing Piperidine and Bipiperidine Groups
No full textThe reaction of N-(phosphonomethyl)piperidine and N,N′-bis(phosphonomethyl)bipiperidine with zirconium(IV) in hydrofluoric acid media led to the preparation of two new zirconium fluoride phosphonate derivatives with 1D and 2D structure, respectively. Their structures were solved ab initio from laboratory powder X-ray diffraction (PXRD) data. The monophosphonate derivative, with formula ZrF2(HF)(O3PCH2NC5H10), has a 1D structure (triclinic, space group P1̅, a = 6.6484(3) Å, b = 7.1396(3) Å, c = 12.2320(6) Å, α = 77.932(4)°, β = 87.031(6)°, γ = 78.953(5)°, V = 557.22(4) Å3, and Z = 2) made of inorganic chains constituted from the connection of zirconium octahedra and phosphorus tetrahedra with the piperidine groups bonded on their external part. The diphosphonate derivative, with formula Zr2F4(HF)2(O3PCH2)NC10H18N(CH2PO3), has a 2D structure (triclinic, space group P1̅, a = 6.6243(3) Å, b = 7.2472(4) Å, c = 12.2550(7) Å, α = 102.879(4)°, β = 100.29(1)°, γ = 101.287(7)°, V = 547.03(4) Å3, and Z = 1) composed of the packing of covalent layers whose structure may be ideally obtained by the joining of adjacent chains of the 1D compound. In these hybrid layers, inorganic regions made of the connectivity of zirconium octahedra and phosphorus tetrahedra alternate with organic regions represented by the bipiperidine moieties. A section dedicated to vibrational spectroscopy analysis is also included, mainly devoted to clarify some issues not easily deducible on the basis of PXRD data and to describe the fluorine environment inside zirconium phosphonate structures
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