On solutions of differential inclusions in homogeneous spaces of functions

In this paper we study the solvability of some classes of differential inclusions with multivalued linear operators in homogeneous spaces of functions. These spaces include a large number of functional spaces like periodic functions and Bohr and Stepanov almost periodic functions. As an application, we consider some existence results for feedback control systems governed by degenerate differential equations of Sobolev type in a Banach space.     

Peculiar behavior of polysaccharide/borax hydrogel tablets: a dynamomechanical characterization

The peculiar unidirectional elongation observed during swelling of tablets prepared with scleroglucan (Sclg) and borax was compared with that of other synthetic and natural polymers capable of physical/chemical interactions with borate ions. A dynamomechanical characterization of “squared” Sclg/borax tablets was carried out to study the differences detectable on the two sides of the matrix corresponding to the two directions, respectively, the parallel and perpendicular one with respect to the applied compression force. Different compression forces were used and, in some cases, a second compression was applied on the tablets along a direction perpendicular to the first one. Birefringence experiments were carried out on the swelled tablets along the two directions. Obtained results allow correlating the anisotropic swelling behavior with the detected dynamomechanical and optical properties of the Sclg/borax system. Among the various tested polymers, only guar gum and, to a lesser extent, locust bean gum, showed an anisotropic elongation during swelling.     

A versatile modular computational tool for complex optoelectronic integrated circuits simulation

A novel graphical computational tool to simulate a wide variety of complex optoelectronic integrated circuits is presented. Based upon a modular approach, this tool reduces the optical circuit into a sequence of interconnected building blocks, each one performing a specific data-flow oriented function onto an input optical stream. The modularity and the flow-based interconnectivity makes this simulator flexible and powerful, yet intuitive. Its execution speed is evaluated using a sophisticated amplifier simulation module that is compared against its replica written in a text-based programming language. More than four times outperformance is reported. The simulator capabilities are further demonstrated through an application example in the field of optical data processing: the analysis of a semiconductor optical amplifier-based Mach–Zehnder interferometer operated as wavelength converter for signals modulated at 40 Gb/s. This simulator represents an attractive alternative to more traditional approaches.     

NH‐Heterocyclic Aryliodonium Salts and their Selective Conversion into N1‐Aryl‐5‐iodoimidazoles

The synthesis of N‐arylimidazoles substituted at the sterically encumbered 5‐position is a challenge for modern synthetic approaches. A new family of imidazolyl aryliodonium salts is reported, which serve as a stepping stone on the way to selective formation of N1‐aryl‐5‐iodoimidazoles. Iodine acts as a “universal” placeholder poised for replacement by aryl substituents. These new λ³‐iodanes are produced by treating the NH‐imidazole with ArI(OAc)₂, and are converted to N1‐aryl‐5‐iodoimidazoles by a selective copper‐catalyzed aryl migration. The method tolerates a variety of aryl fragments and is also applicable to substituted imidazoles.     

The Reaction Pathway of Cellulose Pyrolysis to a Multifunctional Chiral Building Block: The Role of Water Unveiled by a DFT Computational Investigation

LAC (hydroxylactone (1R,5S)‐1‐hydroxy‐3,6‐dioxabicyclo[3.2.1]octan‐2‐one) is one of the most interesting products of the pyrolysis of cellulose and represents a useful chiral building block in organic synthesis. A computational investigation at the DFT level on the mechanism of formation of LAC shows that this species can be obtained following two reaction paths, path A and path B , starting from a well‐known pyrolysis product (ascopyrone P). A series of internal rearrangements involving in all cases a proton transfer leads directly to LAC ( path B ). An alternative path ( path A ) can be also followed. From this path, via a “gate” connecting the two reaction channels, it is possible to reach path B and form LAC. In both cases, the rate‐determining step of the process is the initial keto‐enol isomerization. We found that water, which is present in the reaction mixture, “catalyzes” the reaction by assisting the proton transfers present in all the steps of the process. In particular, water lowers the barrier of the rate‐determining step that becomes 40.9 kcal mol^?1 (79.4 kcal mol^?1 in the absence of water). The corresponding computed rate constant is 4.3×10 s^?1 at 500 °C, a value which is consistent with the presence of LAC in the absence of metal catalysts. The results of this study on the non‐catalyzed process underpin the important role played by water in the formation of pyrolysis products of cellulose where proton transfer is a key mechanistic step.     

Kinematics of single-loop mechanisms and serial robot arms: A systematic approach

This paper presents a systematic approach, based on displacement group properties, to the kinematic analysis of spatial linkages with one closed loop and to the solution of the inverse kinematic problem for robot manipulators. By using the proposed approach, a set of kinematic chains can be determined such that a first closure equation with one unknown can be derived directly and explicitly. Then the remaining closure equations are obtained: it is proved that they can be expressed in triangular form. The basic algorithms used to solve these equations in closed form are also presented. For each algorithm, the conditions of applicability, the initial information required, the results, the type and form of equations, and the maximum number of solutions are given. The proposed approach is well suited to the symbolic explicit solution of the inverse kinematic problem of a wide range of robut mechanisms. An example of its application is given.

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Sommario Il lavoro presenta un appreceio sistematico, basato sulle proprietà dei gruppi di spostamento, all'analisi cinematica di posizione di meccanismi spaziali ad una maglia e alla cinematica inversa di robot manipolatori seriali. L'approccio consente di determinare un insieme di catene cinematiche per le quali può essere scritta e risolta direttamente una prima equazione di chiusura in una sola incognita. Viene successivamente dimostrato esaustivamente che, per tali catene, le successive equazioni di chiusura possono essere espresse e risolte in forma triangolare. Inoltre sono presentati gli algoritmi di base utilizzabili per la soluzione del problema posto. Per ciascuno di essi sono dati: le condizioni di applicabilità, l'informazione iniziale richiesta, i risultati ottenuti, il tipo e la forma delle equazioni e il massimo numero di soluzioni possibili. L'approccio presentato è utilizzabile per la soluzione simbolica esplicita, manuale o automatica, di un esteso insieme di meccanismi per robot. Viene dato un esempio di uso del metodo.

     

Application of a lattice-gas numerical algorithm to modelling water transport in fractured porous media

A 2D lattice-gas numerical algorithm was used to simulate liquid infiltration into unsaturated porous media with a parallel sided central crack. The chosen model, the interacting liquid-gas model of Appert and Zaleski, has dynamic properties leading to a phase transition and liquid and gas phases can be simulated by the model. These two phases are used to simulate biphasic flow in porous media. Fourteen numerical experiments of liquid infiltration were carried out which differed in the morphology of the microporous matrix, in the aperture of the central crack and in the amount of liquid supplied. For the same microporous matrix, the infiltration dynamics in the dual media depended upon the ratio between the amount of liquid supplied and the crack aperture. Variations in water storage over time and liquid flow regimes within the cracks are discussed.     

Physico-Chemical Properties of Inorganic NPs Influence the Absorption Rate of Aquatic Mosses Reducing Cytotoxicity on Intestinal Epithelial Barrier Model

Noble metals nanoparticles (NPs) and metal oxide NPs are widely used in different fields of application and commercial products, exposing living organisms to their potential adverse effects. Recent evidences suggest their presence in the aquifers water and consequently in drinking water. In this work, we have carefully synthesized four types of NPs, namely, silver and gold NPs (Ag NPs and Au NPs) and silica and titanium dioxide NPs (SiO₂ NPs and TiO₂ NPs) having a similar size and negatively charged surfaces. The synthesis of Ag NPs and Au NPs was carried out by colloidal route using silver nitrate (AgNO₃) and tetrachloroauric (III) acid (HAuCl₄) while SiO₂ NPs and TiO₂ NPs were achieved by ternary microemulsion and sol-gel routes, respectively. Once the characterization of NPs was carried out in order to assess their physico-chemical properties, their impact on living cells was studied. We used the human colorectal adenocarcinoma cells (Caco-2), known as the best representative intestinal epithelial barrier model to understand the effects triggered by NPs through ingestion. Then, we moved to explore how water contamination caused by NPs can be lowered by the ability of three species of aquatic moss, namely, Leptodictyum riparium, Vesicularia ferriei, and Taxiphyllum barbieri, to absorb them. The experiments were conducted using two concentrations of NPs (100 μM and 500 Μm as metal content) and two time points (24 h and 48 h), showing a capture rate dependent on the moss species and NPs type. Then, the selected moss species, able to actively capture NPs, appear as a powerful tool capable to purify water from nanostructured materials, and then, to reduce the toxicity associated to the ingestion of contaminated drinking water.