Emulating opportunistic networks with KauNet Triggers

In opportunistic networks the availability of an end-to-end path is no longer required. Instead opportunistic networks may take advantage of temporary connectivity opportunities. Opportunistic networks present a demanding environment for network emulation as the traditional emulation setup, where application/transport endpoints only send and receive packets from the network following a black box approach, is no longer applicable. Opportunistic networking protocols and applications additionally need to react to the dynamics of the underlying network beyond what is conveyed through the exchange of packets. In order to support IP-level emulation evaluations of applications and protocols that react to lower layer events, we have proposed the use of emulation triggers. Emulation triggers can emulate arbitrary cross-layer feedback and can be synchronized with other emulation effects. After introducing the design and implementation of triggers in the KauNet emulator, we describe the integration of triggers with the DTN2 reference implementation and illustrate how the functionality can be used to emulate a classical DTN data-mule scenario

Mesoporous bioactive glass as a multifunctional system for bone regeneration and controlled drug release

Purpose: Coupling the potential for bone regeneration and the ability for in situ controlled drug release in a single device is a challenging field of research in bone tissue engineering; in an attempt to pursue this aim, mesoporous bioactive glass (MBG) membranes belonging to the SiO2-P2O5-CaO ternary system were produced and characterized. Methods: The glass was synthesized via a sol-gel route coupled with an evaporation-induced self-assembly process by using a non-ionic block co-polymer as a mesostructure former. MBG structure and morphology, as well as mesopores size and shape, were investigated by x-ray diffraction, transmission electron microscopy, and N2 adsorption-desorption measurements. In vitro bioactivity was investigated by soaking MBG membranes in simulated body fluid (SBF) for different time frames. Ibuprofen was encapsulated into MBG pores and drug release kinetics in SBF were assessed. Biological tests by using SAOS-2 cells were performed to assess the material cytocompatibility. Results: The material revealed significant ability to induce hydroxyapatite formation on its surface (bioactivity). Drug release kinetics in SBF are very similar to those obtained for mesoporous silica having mesopore size comparable to that of the prepared MBG (∼5 nm). No evidence of cell viability depression was detected during in vitro culture, which demonstrates the good biological compatibility of the material. Conclusions: The easiness of tailoring and shaping, the highly bioactive and biocompatible behavior, and the drug uptake/release ability of the prepared materials may suggest their use as "smart" multifunctional grafts for bone reconstructive surgery

Composizioni eudermiche

DOMANDA DI BREVETT

Pores occlusion in MCM-41 spheres immersed in SBF and the effect on ibuprofen delivery kinetics: a quantitative model

MCM-41 silica particles have been synthesized with size in the low submicron range, loaded with ibuprofen and characterized by means of XRD, N2 adsorption and scanning electron microscopy, coupled with EDS analysis both before and after contact with different volumes of simulated body fluid (SBF) at 37 .C up to 10 h. The particles do not show any change in morphology, composition and mesostructure as a consequence of soaking. MCM-41 spheres, though, are not inert towards SBF. Two processes take place, showing features independent from the soaking volume: (i) one within 1.2 h, bringing about dissolution of silica into the liquid phase up to a concentration of 2.2mM and no change in the mesopore volume; (ii) the second, after an induction period of 1.2 h, bringing about a limited increase in the concentration of dissolved silica, but affecting severely the mesoporous volume, which decreases exponentially with time. Delivery curves differ significantly when varying the volume of SBF used. To account for release kinetics under the circumstances observed, a mathematical model is proposed, based on the standard Noyes.Whitney equation, taking into account both the SBF volume used and the mesopores occlusion, this latter through a time-dependent diffusion coefficient. A satisfactory agreement is observed, without the intervention of any adjustable paramete

Cell-induced Intracellular Controlled Release of Membrane Impermeable Cysteine from a Mesoporous Silica Nanoparticles-based Drug Delivery System

Intracellular thiols are of vital importance for controlling the homeostasis of live cells.1 For example, glutathione (GSH) is one of the agents responsible for the reducing milieu of various cell types. Recent studies have highlighted the key role of GSH in several physiological processes, such as DNA synthesis, microtubular-related processes, immune functions, and protection against oxidative damage induced by free radicals and other toxicants.The low intracellular concentration of GSH has been attributed to several chronic inflammation disorders, which often leads to cancerous, neurodegenerative, and cardiovascular maladies. A variety of therapeutic methods in promoting GSH biosynthesis have been developed for the treatment of these diseases. The success of these approaches hinges upon the availability of intracellular cysteine (Cys). A mesoporous silica nanoparticle-based intracellular cysteine delivery system that could be induced and regulated by cell-produced natural antioxidants was synthesize