On some auxiliary mappings generated by nonexpansive and strictly pseudo-contractive mappings

Starting by a finite family of mappings, we define the concept of procedure with Lipschitzian dependence of the coefficients. We give seven concrete examples of such procedures and prove the strong convergence of two viscosity methods.     

Poly(methyl methacrylate)-Assisted Exfoliation of Graphite and Its Use in Acrylonitrile-Butadiene-Styrene Composites

One of the applications of graphene in which its scalable production is of utmost importance is the development of polymer composites. Among the techniques used to produce graphene flakes, the liquid-phase exfoliation (LPE) of graphite stands out due to its versatility and scalability. However, solvents suitable for the LPE process are generally toxic and have a high boiling point, making the processing challenging. The use of low boiling point solvents could be convenient for the processing, due to the easiness of their removal. In this study, the use of poly(methyl methacrylate) (PMMA) as a stabilizing agent is proposed for the production of graphene flakes in a low boiling point solvent, that is, acetone. The graphene dispersions produced in the mixture acetone-PMMA have higher concentration, +175 %, and contain a higher percentage of few-layer graphene flakes (<5 layers), that is, +60 %, compared to the dispersions prepared in acetone. The as-produced graphene dispersions are used to develop graphene/acrylonitrile-butadiene-styrene composites. The mechanical properties of the pristine polymer are improved, that is, +22 % in the Young's modulus, by adding 0.01 wt. % of graphene flakes. Moreover, a decrease of ≈20 % in the oxygen permeability is obtained by using 0.1 wt. % of graphene flakes filler, compared to the unloaded matrix.     

Azimuthal dependence of forward-jet production in DIS in the high-energy limit

As a signal for the BFKL Pomeron in small-x deep inelastic ep scattering, we calculate the azimuthal dependence of the inclusive cross section of forward jets relative to the outgoing electron. For not very large differences in rapidity between the current jet and the forward jet the cross section peaks at π/2. For increasing rapidity BFKL dynamics predicts a decorrelation in the azimuthal dependence between the electron and the forward jet.     

Exploiting Synergistic Effects in Organozinc Chemistry for Direct Stereoselective C‐Glycosylation Reactions at Room Temperature

Pairing a range of bis(aryl) zinc reagents ZnAr₂ with the stronger Lewis acidic [(ZnAr^F₂)] (Ar^F=C₆F₅), enables highly stereoselective cross‐coupling between glycosyl bromides and ZnAr₂ without the use of a transition metal. Reactions occur at room temperature with excellent levels of stereoselectivity, where ZnAr^F₂ acts as a non‐coupling partner although its presence is crucial for the execution of the C(sp²)–C(sp³) bond formation process. Mechanistic studies have uncovered a unique synergistic partnership between the two zinc reagents, which circumvents the need for transition‐metal catalysis or forcing reaction conditions. Key to the success of the coupling is the avoidance of solvents that act as Lewis bases versus diarylzinc compounds (e.g. THF).     

Time Gauge Fixing and Hilbert Space in Quantum String Cosmology

Recently the low-energy effective string theory has been used by Gasperini and Veneziano to elaborate a very interesting scenario for the early history of the universe (birth of the universe as quantum scattering). Here we investigate the gauge fixing and the problem of the definition of a global time parameter for the quantum form of the model, and obtain the positive norm Hilbert space of states.     

The reactions of phenolic reagents with α-bromo Michael acceptors in the K2CO3-acetone system. A stereospecific AdSNE process.

α-bromo Michael acceptors undergo ipso-substitution by phenol or benzenethiol in the K₂CO₃-acetone system, the reaction originating the (Z) isomers, via a stereospecific Ad_SNE process.     

Cycloaddition reactions of ketoimines. Part II. Synthesis of substituted phenanthridines and cyclopenta[c]quinolines

Substituted 4-benzoyl-3a,4,5,9b-tetrahydro-3H-cyclopenta[c]quinolines 3 and 6-benzoyl-5,6,6a,7,8,10a-hexahydrophenanthridines 10 are obtained through Lewis acid catalyzed addition of 1-phenyl-2-arylamino-2-methoxyethanones 2 to cyclopentadienes and 1,3-cyclohexadiene respectively. Compounds 3 can be converted to the aromatized analogues by reaction with 2,3-dichloro-5,6-dicyanobenzoquinone in refluxing benzene. Compounds 10 are oxidized by sulfur either in decalin or in quinoline to substituted 6-benzoylphenanthridines.