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A micellar approach is proposed to build a series of systems featuring an "off-on-off" fluorescent window response with changes in pH. The solubilizing properties of micelles are used to self-assemble, in water, plain pyrene with lipophilized pyridine and tertiary amine moieties. Since these components are contained in the small volume of the same micelle, pyrene fluorescence is influenced by the basic moieties: protonated pyridines and free tertiary amines behave as quenchers. Accordingly, fluorescence transitions from the "off" to the "on" state, and viceversa, take place when the pH crosses the pK(a) values of the amine and pyridine fragments. To obtain an "off-on-off" fluorescent response in this investigation we use either a set of dibasic lipophilic molecules (containing covalently linked pyridine and tertiary amine groups) or combinations of separate, lipophilic pyridines and tertiary amines. The use of combinations of dibasic and monobasic lipophilic molecules also gives a window-shaped fluorescence response with changes in pH: it is the highest pyridine pK(a) and the lowest tertiary amine pK(a) that determine the window limits. The pK(a) values of all the examined lipophilic molecules were determined in micelles, and compared with the values found for the same molecules in solvent mixtures in which they are molecularly dispersed. The effect of micellization is to significantly lower the observed protonation constants of the lipophilized species. Moreover, the more lipophilic a molecule is, the lower the observed logK value is. Accordingly, changing the substituents on the basic moieties or modifying their structure, tuning the lipophilicity of the mono- or dibases, and choosing among a large set of possible combination of lipophilized mono- and dibases have allowed us to tune, almost at will, both the width and the position along the pH axis of the obtained fluorescent window.

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A new approach based on self-assembly inside micelles has been individuated to prepare a system behaving as a water-operating selective fluorescent sensor for Cu2+ and Ni2+.

pH‐driven double Cu2+ ion translocation occurs inside an heteroditopic macrocycle. The movement opens and closes the system allowing or preventing it to function as receptor for bidentate anions. When imidazole is added to a solution buffered at an appropriate pH value, opening of the system and substrate binding can be induced by the substrate itself, which results in a sharp color change (see picture).

Aim of the present work is to build a link between a structural theory for large-scale analyses of three-dimensional cable structures undergoing, in general, large displacements and rotations, and a refined mechanical description of metallic strands, fully accounting for their composite nature and hysteretic bending behavior. A new formulation for metallic strands is presented. The strand overall mechanical behavior is modeled according to the Euler-Bernoulli beam theory. A constitutive law relating the cross sectional generalized stresses and strains of the adopted structural model is obtained by summing over the individual contributions of wires. Each wire in the strand is individually modeled as a curved thin rod. Kinematic equations are proposed to relate the wire generalized strain variables to those of the strand cross section. The equilibrium of the individual wires is analyzed under the hypothesis of radial contact between adjacent layers taking, most notably, also into account the effects due to the residual radial contact forces induced by the strand manufacturing process. Deformations of contact surfaces are neglected and friction is accounted for, through the Amontons-Coulomb law, in the study of the stick-slip conditions. The proposed sectional model accounts for some distinctive characteristic aspects of wire ropes, such as the coupling between axial force and torque and the non-linear, and non-holonomic, relation between bending moment and curvature, which is a consequence of sliding of wires. The performance of the proposed formulation is assessed with reference to well-documented physical tests and established analytical formulations. Moreover, the role of the residual contact forces due to the stranding process, on the bending behavior of a typical multi-layer strand is assessed

These data indicate that ILR monitoring facilitates the identification of mechanisms responsible for recurrences and therapeutic management in subjects with syncope or pre-syncope and negative traditional neurological and cardiovascular work-up.