We introduce a language competition model that is based on the Abrams-Strogatz model and incorporates the effects of memory and learning in the dynamics of language shift. On a coarse-grained timescale, the effects of memory and learning can be expressed as thresholds on the speakers' fractions of the competing languages. In its simplest form, the resulting model is exactly solvable. Besides the consensus on one of the two languages, the model describes additional equilibrium states that are not present in the Abrams-Strogatz model: a stable dynamical coexistence of the two languages and a frozen state coinciding with the initial state. We show numerically that these results are preserved for threshold functions of a more general shape. The comparison of the model predictions with historical datasets demonstrates that while the Abrams-Strogatz model fails to describe some relevant language competition situations, the proposed model provides a good fitting.

The accurate prediction of drug release kinetics is crucial for designing effective drug delivery formulations. In this context, controlled drug release from hydrogel matrices is a key strategy to enhance therapeutic outcomes while minimizing side effects. In this study, we develop an advanced mathematical model to describe drug release from nanogels, aiming to accurately represent both standard scenarios where the active compound is fully released and cases where diffusion alone is not sufficient to achieve 100% release. The proposed model is based on Fick's diffusion equation but introduces more realistic boundary conditions by eliminating the perfect sink assumption and incorporating a partition coefficient to account for incomplete drug release. The model was applied to six experimental case studies, varying surface charge, pH of the release environment, and nanogel surface functionalization in order to determine the corresponding diffusion coefficient. The results show good agreement with experimental data, providing a consistent interpretation of the release mechanisms observed in the different case studies. This demonstrates the ability of the model to capture the key factors that influence drug release, making it a valuable tool to support the development of new drug delivery systems. By enabling the prediction and optimization of release profiles, the proposed approach can contribute to the design of tailored delivery strategies to achieve improved therapeutic outcomes.

We show that the degree of symmetry of the diversity distribution is the key determinant of global oscillations in coupled networks of FitzHugh-Nagumo units, used as prototypical examples of excitable systems. In these ensembles, symmetric diversity reliably yields resonant collective oscillations-even when all units are individually excitable-whereas asymmetric diversity suppresses them. Two symmetry-based metrics predict the presence or absence of global oscillations from the distribution alone. A simple mean-field mechanism, corroborated by a minimal two-unit analysis, explains how symmetry creates a landscape that supports limit cycles. These results identify diversity distribution symmetry as a key mechanism for emergent synchronization in excitable media.

Networks of heterogeneous oscillators are often seen to display collective synchronized oscillations, even when single elements of the network do not oscillate in isolation. It has been found that it is the diversity of the individual elements that drives the phenomenon, possibly leading to the appearance of a resonance in the response. Here we study the way in which heterogeneity acts in producing an oscillatory regime in a network and show that the resonance response is based on the same physics underlying the resonant translocation regime observed in models of polymer diffusion on a substrate potential. Such a mechanical analog provides an alternative viewpoint that is useful to interpret and understand the nature of collective oscillations in heterogeneous networks.

Hyaluronic acid (HA) based nanogels showed effective intracellular delivery efficacy for anti-cancer and anti-inflammatory drugs, characterized by their ability targeting relevant cell receptors. In the present study, we demonstrate the ability of hyaluronic acid-polyethyleneimine (HA-PEI) nanogels as a promising dual-functional interfacial active for intra-articular injection to intervene arthritis. Nanomechanical measurements on both model substrates and human cartilage samples confirm that the HA-PEI nanogels can significantly improve interfacial lubrication, in comparison to HA molecules, or silica-based nanoparticles. We show that the Coefficient of Friction significantly decreases with a decreasing nanogel size. The exceptional lubricating performance, coupled with the proven drug delivery capability, evidences the great potential of nanoscopic hydrogels for early-stage arthritis treatment. The flexibility in choosing the chemical nature, molecular architecture, and structural characteristics of nanogels makes it possible to modulate both drug delivery kinetics and interfacial lubrication, thus representing an innovative approach to treat degenerative joint diseases.

Nanogels are a prominent research topic in biomedical and drug delivery applications. The versatility of their chemistry allows them to be tailored both to carry and release a wide range of active molecules, and to target specific tissues or cell types. Within a vast field of possible chemical designs, nanogels based on hyaluronic acid seem particularly interesting from the standpoint of dermatological and cosmetic applications, due to the well-known involvement of hyaluronic acid in several fundamental processes related to skin health and ageing. In spite of this, relatively few studies about these nanocarriers and their potential skin-related benefits have appeared so far in the literature. With the aim to stimulate further interest in the topic, in this review, we provide information on hyaluronic acid-based nanogels, including their key physicochemical properties, their typical drug release behavior, and the main synthetic methodologies. The latter include: approaches based on spontaneous self-assembly of polymer molecules; approaches based on chemical cross-linking, where nanogel formation is promoted by covalent bonds between polymer chains; and hybrid approaches that leverage a combination of the above two mechanisms. We believe this body of information, which we collected by going through the relevant literature from the past 10–15 years, offers cosmetic formulators plenty of options to design innovative products.

We develop a three-state agent-based language competition model that takes into account the fact that language learning and attrition are not instantaneous but occur over a finite time interval; i.e., we introduce memory in the system. We show that memory effects significantly impact the dynamics of language competition. Furthermore, we find that including heterogeneity in the linguistic skills of the agents affects the results substantially. We also explore the role of other factors, such as different levels of language learning difficulty, initial population fractions, and daily interaction rates.

The emulsion/evaporation method represents a pivotal approach to synthesize nanogels for controlled drug delivery. However, this strategy is constrained to the use of at least one polymer characterized by a phase-selective solubility in organic or aqueous solutions. Consequently, the formulation of nanoscaffolds based solely on hydrophilic polymers is not feasible by this approach, limiting the applicability of the technique. This work shows an innovative emulsion-based strategy, where two polymers insoluble in water-immiscible organic solvents, hyaluronic acid (HA) and polyethyleneimine (PEI), chemically crosslink to produce nanogels. The procedure exploits the interfacial interactions and the coalescence phenomena occurring in a surfactant-free mixed emulsion, composed of HA and PEI aqueous solutions as dispersed phases and a neat organic solvent as the continuous phase. Our method allows us to obtain HA-PEI nanogels characterized by low polydispersity, good colloidal stability, and high batch-to-batch reproducibility. The synthesized nanoscaffolds were validated as nanocarriers for the controlled release of doxorubicin in ovarian cancer, showing a sustained drug release profile (up to 15 days), which enhanced the therapeutic effects compared to the drug administration in the free form. In particular, through an in vitro assay with a CD44 blocking/ neutralizing antibody, we showed that the hyaluronan receptor was involved in the nanogel internalization process, suggesting that our nanogel formulation, obtained through a surfactant-free mixed emulsion, is a promising strategy for the design of HA-based nanocarriers for CD44-targeted therapy.

We study the interplay between diversity and noise in a 3D network of FitzHugh-Nagumo elements, with topology and dimensions chosen to model a pancreatic beta-cell cluster, as an example of an excitable cell network. Our results show that diversity and noise are not equivalent sources of disorder but have different effects on network dynamics. Their synchronization mechanisms may act independently of one another or synergistically, depending on the mean value of the diversity distribution compared to the intrinsic oscillatory range of the network elements.

We analyze the effect of small-amplitude noise and heterogeneity in a network of coupled excitable oscillators with strong timescale separation. Using mean-field analysis, we uncover the mechanism of a nontrivial effect-diversity-induced decoherence (DIDC)-in which heterogeneity modulates the mechanism of self-induced stochastic resonance to inhibit the coherence of oscillations. We argue that DIDC may offer one possible mechanism via which, in excitable neural systems, generic heterogeneity and background noise can synergistically prevent unwanted resonances that may be related to hyperkinetic movement disorders.

Conventional batch syntheses of polymer-based nanoparticles show considerable shortcomings in terms of scarce control over nanomaterials morphology and limited lot-to-lot reproducibility. Droplet-based microfluidics represents a valuable strategy to overcome these constraints, exploiting the formation of nanoparticles within discrete microdroplets. In this work, we synthesized nanogels (NGs) composed of hyaluronic acid and polyethyleneimine using a microfluidic flow-focusing device endowed with a pressure-driven micro-actuator. The actuator achieves real-time modulation of the junction orifice width, thereby regulating the microdroplet diameter and, as a result, the NG size. Acting on process parameters, NG hydrodynamic diameter could be tuned in the range 92-190 nm while preserving an extremely low polydispersity (0.015); those values are hardly achievable in batch syntheses and underline the strength of our toolbox for the continuous in-flow synthesis of nanocarriers. Furthermore, NGs were validated in vitro as a drug delivery system in a representative case study still lacking an effective therapeutic treatment: ovarian cancer. Using doxorubicin as a chemotherapeutic agent, we show that NG-mediated release of the drug results in an enhanced antiblastic effect vs. the non-encapsulated administration route even at sublethal dosages, highlighting the wide applicability of our microfluidics-enabled nanomaterials in healthcare scenarios.

Using the FitzHugh-Nagumo equations to represent the oscillatory electrical behavior of β-cells, we develop a coupled oscillator network model with cubic lattice topology, showing that the emergence of pacemakers or hubs in the system can be viewed as a natural consequence of oscillator population diversity. The optimal hub to nonhub ratio is determined by the position of the diversity-induced resonance maximum for a given set of FitzHugh-Nagumo equation parameters and is predicted by the model to be in a range that is fully consistent with experimental observations. The model also suggests that hubs in a β-cell network should have the ability to "switch on" and "off" their pacemaker function. As a consequence, their relative amount in the population can vary in order to ensure an optimal oscillatory performance of the network in response to environmental changes, such as variations of an external stimulus.

La presente invention concerne, d'une maniere generale, des compositions de nettoyage, et plus specifiquement des compositions de nettoyage contenant une polyetheramine, un polymere de liberation des salissures et une carboxymethylceullulose, ce qui est approprie pour l'elimination des taches sur des materiaux souilles.