Extreme multistability in a Josephson-junction-based circuit.

We design and report an electrical circuit using a Josephson junction under periodic forcing that reveals extreme multistability. Its overall state equations surprisingly recall those of a well-known model of Josephson junction initially introduced in our circuit. The final circuit is characterized by the presence of two new and different current sources in parallel with the nonlinear internal current source sin[ϕ(t)] of the Josephson junction single electronic component. Furthermore, the model presents an interesting extreme multistability which is justified by a very large number of different attractors (chaotic or not) when slightly changing the initial conditions.

Periodicity, chaos, and multiple attractors in a memristor-based Shinriki's circuit.

In this contribution, a novel memristor-based oscillator, obtained from Shinriki's circuit by substituting the nonlinear positive conductance with a first order memristive diode bridge, is introduced. The model is described by a continuous time four-dimensional autonomous system with smooth nonlinearities. The basic dynamical properties of the system are investigated including equilibria and stability, phase portraits, frequency spectra, bifurcation diagrams, and Lyapunov exponents' spectrum. It is found that in addition to the classical period-doubling and symmetry restoring crisis scenarios reported in the original circuit, the memristor-based oscillator experiences the unusual and striking feature of multiple attractors (i.e., coexistence of a pair of asymmetric periodic attractors with a pair of asymmetric chaotic ones) over a broad range of circuit parameters. Results of theoretical analyses are verified by laboratory experimental measurements.

[In vitro study of the adsorption of chloroquine by an antidiarrheal remedy traditionally used in Africa]. / Etude in vitro de l'adsorption de la chloroquine par un remède antidiarrhéique employé traditionnellement en Afrique.

Mouboumou is a traditional medicine prepared from the inner part of termitarium and is used in traditional medicine in Zaire. In tropical diseases, antimalarial drugs are often used simultaneously with antidiarrheal absorbent drugs, which might, by their adsorbent properties, compromise the efficacy of the antimalarial treatment. The present in vitro study has allowed to determine the adsorption characteristics of chloroquine on Mouboumou; kaopectate was used a reference adsorbent. The adsorption of chloroquine by these two adsorbents is very important (from 30 to 60%) and fits quite well in with the Langmuir's relation. A decrease of bioavailability of chloroquine, due to the adsorption phenomena, might be observed in vivo and could contraindicate the concomitant administration of these drugs.