Composite particles of polyethylene @ silica

Polyethylene (PE) and silica are perhaps the simplest and most common organic and inorganic polymers, respectively. We describe, for the first time, a physically interpenetrating nanocomposite between these two elementary polymers. While polymer-silica composites are well known, the nanometric physical blending of PE and silica has remained a challenge. A method for the preparation of such materials, which is based on the entrapment of dissolved PE in a polymerizing tetraethoxysilane (TEOS) system, has been developed. Specifically, the preparation of submicron particles of low-density PE@silica and high-density PE@silica is detailed, which is based on carrying out a silica sol-gel polycondensation process within emulsion droplets of TEOS dissolved PE, at elevated temperatures. The key to the successful preparation of this new composite has been the identification of a surfactant, PE-b-PEG, that is capable of stabilizing the emulsion and promoting the dissolution of the PE. A mechanism for the formation of the particles as well as their inner structure are proposed, based on a large battery of analyses, including transmission electron microscopy (TEM) and scanning electron microscopies (SEM), surface area and porosity analyses, various thermal analyses including thermal gravimetric analysis (TGA/DTA) and differential scanning calorimetry (DSC) measurements, small-angle X-ray scattering (SAXS) measurements and solid-state NMR spectroscopy.     

Elasticity of crystalline beta-sheet monolayers

Designed amphiphilic beta-sheet peptides with the sequence Pro-Glu-(Phe-Glu)(n)-Pro (n = 2-7) were previously shown by grazing incidence X-ray diffraction (GIXD), to form ordered two-dimensional (2-D) monolayer structures at interfaces induced by the proline residues at peptide termini. The GIXD diffraction pattern was modeled with two coexisting lattice arrangements, suggesting structural flexibility exhibited in the multiple ways by which beta-strands and their amino acid side chains pack into ordered 2-D structures. Here, we find by in-situ GIXD measurements that the ordered beta-sheet assemblies may undergo a quasi-reversible compression and expansion cycle at the air-water interface. The diffraction measurements indicate that on compression the repeat distance that corresponds to the long axes of the peptide strands may decrease by up to 37% in length. Upon expansion the compressed beta-sheet assemblies revert elastically to their original conformation. The interstrand repeat distance along the peptide hydrogen bonds apparently does not change along the film compression and expansion. Based on the GIXD data, at surface pressures higher than approximately 3 mN/m, beyond the peptide limiting area per molecule, the compressibility is 7.4 +/- 0.6 m/N. The out-of-plane Bragg rod diffraction patterns imply that in the compressed state the beta-strands buckle up in reaction to the increase in surface pressure. At low surface pressure, the 2-D compressibility of the crystalline beta-sheet was estimated at approximately 32 m/N attributed to interdomain rearrangements.     

On Quasi-Hyperideals in Semihypergroups

In this article, we introduce the notion of quasi-hyperideal in semihypergroups, and moreover, we introduce the notions of an (m, n)-quasi-hyper-ideal, n-right hyperideal, and m-left hyperideal in semihypergroups, and relations between them are studied. We obtain different characterizations concerning different properties of (m, n)-quasi-hyperideals, minimal (m, n)-quasi-hyperideals, minimal m-left hyperideals, and minimal n-right hyperideals, and relations between them are investigated. Also, some intersection properties and characterizations of (m, n)-quasi-hyperideals of semihyperideals and regular semihyperideals have been studied. In the sequel, m-left simple, n-right simple, and (m, n)-quasi-simple semihypergroups are defined, and some properties of them are investigated.     

On Green’s Relations, 2~0-regularity and Quasi-ideals in Γ-semigroups

In this paper, we introduce the definition of ( m, n) 0-regularity in Γ-semigroups. We investigate and characterize the 20-regular class of Γ-semigroups using Green's relations. Extending and generalizing the Croisot's Theory of Decomposition for Γ-semigroups, we introduce and study the absorbent and regular absorbent Γ-semigroups. We approach this problem by examining quasi-ideals using Green's relations.     

In Process Citation

In studies of the reactivity of oxygen heterocycles, it has been found that khelline gives a molar reacting ratio of 1:16 with vanadate in 2.5M sulphuric acid, the products being vanadium(IV), 2.3 furan dicarboxylic acid, formic acid, acetic acid and carbon dioxide. This reaction can be used for determination of khelline and also for preparation of 2,3-furan dicarboxylic acid.