Sources recovery from boundary data: A model related to electroencephalography

We are concerned with an inverse problem related to sources detection from boundary data in a 2D medium with piecewise constant conductivity. It stands as a 2D version of the inverse problem of electroencephalography, where pointwise sources model epilepsy foci, with the so-called multi-layer spherical model of the head (scalp, skull, brain). When overdetermined electrical measurements (potential and current flux) are available on the scalp, one wants to recover the current sources (conductivity defaults) located in the brain (inner boundary). This recovery issue reduces to a number of inverse problems, where the sources identification process makes use of best rational approximation in the disk, whereas the preliminary cortical mapping step (Cauchy type issue) relies on best constrained harmonic or analytic approximation in an annulus (bounded extremal problems).     

Competitive Processes in Controlled Cationic Ring-Opening Polymerization of Oxetane: a Lotka-Volterra Predator-Prey Model of Two Growing Species Competing for the same Resources

Summary : The activation-deactivation pseudo-equilibrium coefficient Q_t and constant K₀ (=Q_t x P_aT1,t = ([A1]x[Ox])/([T1]x[T])) as well as the factor of activation (P_aT1,t) and rate constants of elementary steps reactions that govern the increase of M_n with conversion in controlled cationic ring-opening polymerization of oxetane (Ox) in 1,4-dioxane (1,4-D) and in tetrahydropyran (THP) (i.e. cyclic ethers which have no homopolymerizability (T)) were determined using terminal-model kinetics. We show analytically that the dynamic behavior of the two growing species (A1 and T1) competing for the same resources (Ox and T) follows a Lotka-Volterra model of predator-prey interactions.     

Strontium hexabromodicadmate(II) octahydrate

The ternary system SrBr₂–CdBr₂–H₂O was investigated at room temperature. The title phase, SrCd₂Br₆·8H₂O, has been isolated from this system and its structure determined by single‐crystal X‐ray diffraction. The structure consists of infinite double chains of CdBr₆ octahedra and chains of Sr(H₂O)₉ polyhedra packed along the b axis. The interaction between these two isolated chains occurs through O—H⃛O and O—H⃛Br hydrogen bonds. The structure is compared with that of SrCd₂Cl₆·8H₂O.     

Synthesis of core-shell material rich in carboxyl groups and its application in the selective adsorption of cationic peptides

The ability to extract peptides and proteins from biological samples with excellent reusability, high adsorption capacity, and great selectivity is essential in scientific research and medical applications. Inspired by the advantages of core-shell materials, we fabricated a core-shell material using amino-functionalized silica as the core. Benzene-1,3,5-tricarbaldehyde and 3,5-diaminobenzoic acid were used as model organic ligands to construct a shell coating by alternately reacting the two monomers on the surface of silica microspheres. The resultant material featured an outstanding capability for the adsorption of cationic peptides, most likely owing to its porous structure, a large number of carboxylic functional groups, and low mass-transfer resistance. The maximum saturated adsorption capacity reached 833.3 mg/g and the adsorption process took only 20 min. Under optimized adsorption conditions, the core-shell material was used to selectively adsorb cationic peptides from the tryptic digestive solution of lysozyme and bovine serum albumin, Specifically, the analysis results showed seven cationic peptides in the eluate and twenty anionic peptides in the supernatant, which indicates the efficient trap of most cationic peptides in the digestive solution.