Accelerated exchange in polyelectrolyte multilayers by "catalytic" polyvalent ion pairing

Self-exchange of isotopically labeled polycarboxylic acid within a polyelectrolyte multilayer proceeds to completion and is reversible. Similar exchange with poly(styrene sulfonate), which forms nonlabile polyelectrolyte complexes, is slow and irreversible but is facilitated by polyvalent ion pairing interventions of a third polyelectrolyte. This is an example of accelerated kinetics in "sticky" synthetic systems associated by nonspecific polyvalent interactions.     

New Preparation of (Z)-1-Phenyl-3-cyano-2-propen-1-ones

Reaction of γ-phenyl-β,γ-unsaturated hydroxamates with bis(collidine)bromine(I) hexafluorophosphate led to the formation of cyclic bromo imidates. Reaction of these with triethylamine led to the formation of 3-cyano-2-propen-1-ones with good yields by a fragmentation reaction.     

Polytetrafluoroethylene Sputtered PES Membranes for Membrane Distillation: Influence of RF Magnetron Sputtering Conditions

Thin films of fluorocarbon were deposited on polyethersulfone membranes via argon plasma sputtering of a poly(tetrafluoroethylene) (PTFE) target in an RF magnetron plasma reactor. The obtained deposited ultrathin coatings had nanoscale roughnesses and high degrees of fluorination. The intensity of fluorine atom in plasma environment during fluorocarbon deposition was investigated. Depending on the deposition conditions comprising working gas pressure, applied RF power, and distance between the target and the substrate, polymeric films with different chemical compositions and/or morphologies were obtained. The morphologies of the films were analyzed by means of SEM, XPS, and AFM. The results suggested that the sputtered film deposited at a higher pressure and longer target–substrate distance and moderate RF power had a surface composition and chemical structure closer to those of the PTFE film. The treated hydrophobic PES membranes with water contact angles as high as 115° were applied for the first time in an air gap membrane distillation setup for removal of benzene as a volatile organic compound from water. The results showed that the plasma-treated membranes have a comparable or superior performance to that of commercial PTFE used in membrane distillation with similar permeate flux and separation factor after 20 h long term performance.     

Qualitative Properties of Eigenvectors Related to Multivalued Operators and some Existence Results

In this work, we study a class of nonlinear eigenvalue problems related to fully discontinuous operators. In particular, we prove the existence of a critical point for two distinct problems. Connected with this problem, we also study a minimization problem with constraint, and we investigate the existence of solutions for a resonant case near zero. Moreover, we give some estimates and qualitative properties of solutions by using the relative rearrangement theory.     

Entropy and renormalized solutions for nonlinear elliptic problem involving variable exponent and measure data

We give an existence result of entropy and renormalized solutions for strongly nonlinear elliptic equations in the framework of Sobolev spaces with variable exponents of the type:-div(a(x, u, u) + φ(u)) + g(x, u, u) = μ, where the right-hand side belongs to L1(Ω) + W-1,p(x)(Ω),-div(a(x, u, u)) is a Leray–Lions oper- ator defined from W-1,p(x)(Ω) into its dual and φ∈ C0(R, RN). The function g(x, u, u) is a non linear lower order term with natural growth with respect to |u| satisfying the sign condition, that is,g(x, u, u)u ≥ 0.     

Cosynthesis, coexistence, and self-organization of alpha- and beta-cobalt hydroxide based on diffusion and reaction in organic gels

We report the cosynthesis of highly stable laminated single crystal alpha- and beta-Co(OH) 2 using the reaction and diffusion of a hydroxide solution into a gel containing Co(II). The obtained alpha-Co(OH) 2, which is known to be thermodynamically unstable and transforms in a short period of time to the beta form, has been stabilized in the gel medium for weeks. The system also exhibits Liesegang banding where complicated spatial dynamics during the formation of the two polymorphs are shown to take place.     

Immobilized polyoxometalates onto mesoporous organically-modified silica aerogels as selective heterogeneous catalysts of anthracene oxidation

Immobilized molybdovanadophosphoric acids onto organically surface-modified silica aerogels were successfully prepared and investigated in heterogeneous catalysis of anthracene oxidation. The catalysts were obtained by supporting mono- and di-vanadium substituted molybdophosphoric acids on hybrid silica materials synthesized via the sol–gel process followed by surface amino-functionalization. The FTIR, DR UV–vis, and AA spectroscopy confirmed the loading and distribution of the polyoxometalate molecules on the surface of the aerogels. The nitrogen adsorption–desorption technique revealed a systematic decrease in the specific surface area and pore volume after the immobilization of the polyoxometalates. The application of the supported molecules as catalysts for anthracene oxidation showed 100% selectivity for 9,10-anthraquinone as opposed to the reactions conducted under homogeneous conditions. Moreover, at certain conditions, the catalytic activity of the supported polyoxometalates was greater than their corresponding free polyoxometalates with a clear effect of the surface chemical groups of the supporting silica aerogels. Additionally, the oxidant and solvent nature showed a crucial effect on the catalytic activity and selectivity of the immobilized polyoxometales. The heterogeneous catalysts were regenerated and reused over consecutive catalytic cycles reflecting a potential economic interest in these materials besides their high efficiency in heterogeneous catalysis.     

Biochemical studies on the production of Sparsomycin antibiotic by Pseudomonas aeurginosa,AZ-SH-B8 using plastic wastes as fermented substrate

Hundred and twenty microbial isolates could be isolated from different soil samples collected from different localities in Egypt. One of the bacterial cultures AZ-SH-B8 was found to produce a wide spectrum antimicrobial agent when cultivated on plastic wastes. The bacterial culture AZ-SH-B8 could be isolated from a soil sample collected from Sharkia governorate, Egypt. From the taxonomic features, the bacterial isolate AZ-SH-B8 matches with Pseudomonas aeurginosa in the morphological, physiological and biochemical characters and confirmation by using API20E system. Thus, it was given the suggested name P. aeurginosa, AZ-SH-B8. The parameters controlling the biosynthetic process of antimicrobial agent formation includes: innoculum size, different pH values, different temperatures, different incubation period, different carbon and nitrogen sources and different mineral salts concentrations (KNO₃, K₂HPO₄, MgSO₄·7H₂O and KCl) were fully investigated. The active metabolite was extracted using n-butanol (1:1, v/v) at pH 7.0. The separation of the active ingredient and its purification was performed using both thin layer chromatography (TLC) and column chromatography (CC) techniques. The physico-chemical characteristics of the purified antibiotic viz. color, melting point, solubility, elemental analysis, spectroscopic characteristics and chemical reactions have been investigated. This analysis indicates a suggested empirical formula of C₁₃H₂₁N₃O₆S₂. The minimum inhibition concentrations “MICs” of the purified antimicrobial agent were also determined. The purified antimicrobial agent was suggestive of belonging to Sparsomycin antibiotic produced by P. aeurginosa, AZ-SH-B8.     

Entanglement Dynamics of Disordered Quantum XY Chains

We consider the dynamics of the quantum XY chain with disorder under the general assumption that the expectation of the eigenfunction correlator of the associated one-particle Hamiltonian satisfies a decay estimate typical of Anderson localization. We show that, starting from a broad class of product initial states, entanglement remains bounded for all times. For the XX chain, we also derive bounds on the particle transport which, in particular, show that the density profile of initial states that consist of fully occupied and empty intervals only have significant dynamics near the edges of those intervals, uniformly for all times.     

Onion phases as biomimetic confined media for silica nanoparticle growth

Phospholipid onion phases were investigated as biomimetic media for the synthesis of silica in a confined environment. Stable multilamellar nanovesicles incorporating sodium silicate solutions could be obtained. Upon aging, silica condensation occurs in the onion interlayer space while preserving the initial multilamellar organization. The hybrid structure consists of an array of apparently unconnected silica nanoparticles in the 20-30 A size range packed in the vesicular 50 A interlayer space, suggesting that the silica growth was efficiently controlled by its confinement in the onion lamellar organization.