Transport of measures on networks

In this paper we formulate a theory of measure-valued linear transport equations on networks. The building block of our approach is the initial/boundary-value problem for the measure-valued linear transport equation on a bounded interval, which is the prototype of an arc of the network. For this problem we give an explicit representation formula of the solution, which also considers the total mass flowing out of the interval. Then we construct the global solution on the network by gluing all the measure-valued solutions on the arcs by means of appropriate distribution rules at the vertexes. The measure-valued approach makes our framework suitable to deal with multiscale flows on networks, with the microscopic and macroscopic phases represented by Lebesgue-singular and Lebesgue-absolutely continuous measures, respectively, in time and space

A measure theoretic approach to traffic flow optimization on networks

We consider a class of optimal control problems for measure-valued nonlinear transport equations describing traffic flow problems on networks. The objective isto minimise/maximise macroscopic quantities, such as traffic volume or average speed,controlling few agents, for example smart traffic lights and automated cars. The measuretheoretic approach allows to study in a same setting local and nonlocal drivers interactionsand to consider the control variables as additional measures interacting with the driversdistribution. We also propose a gradient descent adjoint-based optimization method, ob-tained by deriving first-order optimality conditions for the control problem, and we providesome numerical experiments in the case of smart traffic lights for a 2-1 junction.Comment: 20 pages, 6 figure

EFFETTO DI TIPOLOGIA E FUNZIONALIZZAZIONE DI NANOTUBI DI CARBONIO SULLE PROPRIETA’ DI FIBRE A MATRICE POLIAMMIDICA

Si riportano i risultati relativi all'utilizzo di due campioni di CNT: uno commerciale (purezza 90%, L/D ≈ 50) ed uno sintetizzato e purificato ad hoc (purezza 99%, L/D ≈ 500) come filler per la realizzazione di fibre a matrice poliammidica. In particolare, si è investigato l’effetto della funzionalizzazione mediante plasma sulle proprietà reologiche, meccaniche ed elettriche delle fibre ottenute. La quantità di carica (2%) e le condizioni operative di trattamento al plasma sono state ricavate da studi precedenti. Le misure di viscosità elongazionale condotte sui campioni a base di CNT tal quali e funzionalizzati hanno messo in luce come l’introduzione della carica comporti un netto incremento della MS a fronte di una diminuzione della BSR. I test di trazione hanno fatto registrare un effetto positivo di fattore di forma e funzionalizzazione sul modulo elastico e sulle proprietà a rottura delle fibre caricate. L’analisi morfologica delle fibre rivela che dopo la funzionalizzazione si registrano livelli di dispersione, allineamento e adesione interfacciale decisamente più alti. La natura delle interazioni matrice-carica varia a seconda della tipologia di CNT: nelle fibre a base di CNT commerciali funzionalizzati si assiste alla formazione di strutture simili a quelle Shish-kebab, nelle fibre a base di CNT di sintesi si registrano fenomeni di wrapping di polimero sulle pareti dei CNT. Le proprietà elettriche del materiale migliorano con l’introduzione della carica, i CNT di sintesi si rivelano migliori di quelli commerciali. L’effetto della funzionalizzazione non altera significativamente i valori di conducibilità dei materiali

Enhancing the mechanical performance of polymer based nanocomposites by plasma-modification of nanoparticles

The possibility of enhancing the mechanical performance of two different polymer-based nanocomposites using polyamide 6 (PA6) and poly[ethylene-co-(vinyl acetate)] (EVA) as matrices was investigated. The nanofillers used were, respectively, either carbon nanotubes (CNTs) or an organically modified montmorillonite (Cloisite 15A), both previously modified by plasma treatment to introduce polar moieties. The nanofillers were fully characterized by Raman spectroscopy, XPS, FT-IR and XRD, demonstrating their effective modification with oxygenated groups. The nanocomposites were prepared by melt processing in order to obtain films and fibres. The mechanical tests carried out on the nanocomposites showed a remarkable increase of the elastic modulus when plasma modified nanoparticles were used. The improvement of wettability and dispersion of the nanofillers in the polymer matrices, as confirmed by SEM observations, can be invoked to explain this feature

Comportamento di nanocompositi PA6/CNT in flusso elongazionale non isotermo

Si sono preparate fibre a matrice poliammidica caricate con CNT. Sono state utilizzate due diverse tipologie di CNT a differente fattore di forma e grado di purezza, ossidate mediante plasma di ossigeno. Le misure di viscosità elongazionale hanno evidenziato che l’introduzione della carica comporta un incremento della MS a fronte di una diminuzione della BSR per tutti i materiali caricati. La tipologia e la funzionalizzazione dei CNT hanno delle notevoli ricadute sul diverso comportamento reologico. Studi morfologici hanno evidenziato che dopo la funzionalizzazione si registrano livelli di dispersione, allineamento e adesione interfacciale più alti. La natura delle interazioni matrice-carica varia a seconda della tipologia e della funzionalizzazione dei CNT: si assiste a fenomeni di wrapping e bridging. Le proprietà meccaniche aumentano con l’aumentare del fattore di forma della carica e dopo la funzionalizzazione. Le proprietà elettriche dipendono più dal fattore di forma che dalla funzionalizzazione

Multifunctional green composites based on plasma-activated and GO-coated dwarf palm fibers

In this work, we propose a green method for decorating natural fibers derived from dwarf palm waste with graphene oxide (GO) sheets. In detail, plasma-treatment was used to activate fiber surface for the subsequent GO-coating, which was performed in water. Poly(butylene adipate-co-terephthalate) (PBAT)-based composites incorporating 50 % of either raw, plasma-modified or hybrid fibers were prepared by compression moulding and thoroughly analysed to investigate the processing-structure-properties relationships of these systems. The outcomes reveal that combining plasma treatment and GO coating enables fabricating green composites with significantly improved mechanical performance (stiffness and tensile strength increments of up to 500 % and 300 %, respectively) and electrical conductivity on the order of 10(-6) S/m

Dengue Virus Genome Uncoating Requires Ubiquitination

The process of genome release or uncoating after viral entry is one of the least-studied steps in the flavivirus life cycle. Flaviviruses are mainly arthropod-borne viruses, including emerging and reemerging pathogens such as dengue, Zika, and West Nile viruses. Currently, dengue virus is one of the most significant human viral pathogens transmitted by mosquitoes and is responsible for about 390 million infections every year around the world. Here, we examined for the first time molecular aspects of dengue virus genome uncoating. We followed the fate of the capsid protein and RNA genome early during infection and found that capsid is degraded after viral internalization by the host ubiquitin-proteasome system. However, proteasome activity and capsid degradation were not necessary to free the genome for initial viral translation. Unexpectedly, genome uncoating was blocked by inhibiting ubiquitination. Using different assays to bypass entry and evaluate the first rounds of viral translation, a narrow window of time during infection that requires ubiquitination but not proteasome activity was identified. In this regard, ubiquitin E1-activating enzyme inhibition was sufficient to stabilize the incoming viral genome in the cytoplasm of infected cells, causing its retention in either endosomes or nucleocapsids. Our data support a model in which dengue virus genome uncoating requires a nondegradative ubiquitination step, providing new insights into this crucial but understudied viral process. IMPORTANCE: Dengue is the most significant arthropod-borne viral infection in humans. Although the number of cases increases every year, there are no approved therapeutics available for the treatment of dengue infection, and many basic aspects of the viral biology remain elusive. After entry, the viral membrane must fuse with the endosomal membrane to deliver the viral genome into the cytoplasm for translation and replication. A great deal of information has been obtained in the last decade regarding molecular aspects of the fusion step, but little is known about the events that follow this process, which leads to viral RNA release from the nucleocapsid. Here, we investigated the fate of nucleocapsid components (capsid protein and viral genome) during the infection process and found that capsid is degraded by the ubiquitin-proteasome system. However, in contrast to that observed for other RNA and DNA viruses, dengue virus capsid degradation was not responsible for genome uncoating. Interestingly, we found that dengue virus genome release requires a nondegradative ubiquitination step. These results provide the first insights into dengue virus uncoating and present new opportunities for antiviral intervention.Fil: Byk, Laura Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Iglesias, Nestor Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: de Maio, Federico Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Gebhard, Leopoldo German. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Rossi, Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación en Biomedicina de Buenos Aires - Instituto Partner de la Sociedad Max Planck; ArgentinaFil: Gamarnik, Andrea Vanesa. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentin

Electrospun polymeric nanohybrids with outstanding pollutants adsorption and electroactivity for water treatment and sensing devices

Graphene oxide (GO) and carbon nanotubes (CNTs) were loaded at different mutual ratios into poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP) matrix and electrospun to construct mats that were assessed as smart sorbents for decontaminating water from methylene blue (MB) pollutant, while ensuring the additional possibility of detecting the dye amounts. The results revealed that sorption capacity enhances upon increasing GO content, which is beneficial to wettability and active area. Equilibrium adsorption of these materials is precisely predicted by the Langmuir isotherm model and the maximum capacities herein achieved, ranging from 120 to 555 mg/g depending on the formulation, are higher than those reported for similar systems. The evolution of the structure and properties of such materials as a function of dye adsorption was studied. The results reveal that MB molecules prompted the increase of electrical conductivity of the samples in a dose-dependent manner. Mats containing solely CNTs, while displaying the worst sorption performance, showed the highest electrical performances, displaying interesting changes in their electrical response as a function of the dye amount adsorbed, with a linear response and high sensitivity (309.4 mu S cm-1 mg-1) in the range 0-235 mu g of dye adsorbed. Beyond the possibility to monitor the presence of small amounts of MB in contaminated water and the saturation state of sorbents, this feature could even be exploited to transform waste sorbents into high-added value products, including flexible sensors for detecting low values of pressure, human motion, and so on