A Universal Measure

It is shown that for any ring R of sets there is a locally convex Hausdorff topological vector space M(R) and a measure χ : R → M(R) such that for any other locally convex Hausdorff topological vector space W and any measure µ : R → W, there exists a unique continuous linear map µ : M(R) → W such that . Measure is defined in such a way that M(R)′, the space of all continuous linear functionals on M(R), corresponds to all finite, signed measures in the usual sense when R is a σ-ring. The problem of extending measures from R to the σ-ring generated by R is formulted in this setting. Properties of the universal measure χ are described. The topology of M(R) is studied via the pairing <M(R), M(R)′>. For example, the weak compact subsets of M(R)′ are characterized. This characterization gives rise to a simple proof of the Orlicz-Pettis theorem.     

Choline Chloride-Based Deep Eutectic Solvents as Green Effective Medium for Quaternization Reactions

The Menshutkin reaction represents the alkylation of tertiary amines by alkyl halide where the reactants are neutral and the products, quaternary ammonium salts, are two ions with opposite signs. The most commonly used organic solvents in quaternization reactions are volatile organic solvents (VOSs), namely acetone, anhydrous benzene, dry dichloromethane (DCM), dimethylformamide (DMF) and acetonitrile (ACN). The purpose of this work was to examine eutectic solvents as a “greener” alternative to conventional solvents so that quaternization reactions take place in accordance with the principles of green chemistry. Herein, sixteen eutectic solvents were used as replacements for volatile organic ones in quaternization reactions of isonicotinamide with substituted phenacyl bromides. The reactions were carried out at 80 °C by three synthetic approaches: conventional (4–6 h), microwave (20 min) and ultrasound (3 h). Microwave-assisted organic reactions produced the highest yields, where in several reactions, the yield was almost quantitative. The most suitable eutectic solvents were based on choline chloride (ChCl) as the hydrogen bond acceptor (HBA) and glycerol, oxalic or levulinic acid as hydrogen bond donors (HBDs). The benefits of these three deep eutectic solvents (DESs) as a medium for quaternization reactions are the simplicity of their preparation for large-scale production, with inexpensive, available and nontoxic starting materials, as well as their biodegradability.     

Structure of amorphous GeSe thin films

Amorphous films of GeSe_0.7 and GeSe_2.4 have been examined by energy-filtered scanning electron diffraction and by electron microscopy. Radial distribution analysis of the GeSe_0.7 intensity curves indicates that the local atomic order of these films differs considerably from the distorted rocksalt structure of bulk crystalline GeSe. Radial distribution studies also indicate a change in the structure of GeSe_0.7 and GeSe_2.4 films supported on copper mesh as they are heated with an electron beam. Gross structural features are not observable in the electron micrographs of the amorphous films. This does not eliminate, however, the possibility of the presence of glassy phase separation on a fine scale in the heat-treated films.     

Quantum dynamics of the femtosecond photoisomerization of retinal in bacteriorhodopsin

The membrane protein bacteriorhodopsin contains all-trans-retinal in a binding site lined by amino acid side groups and water molecules that guide the photodynamics of retinal. Upon absorption of light, retinal undergoes a subpicosecond all-trans-->13-cis phototransformation involving torsion around a double bond. The main reaction product triggers later events in the protein that induce pumping of a proton through bacteriorhodopsin. Quantum-chemical calculations suggest that three coupled electronic states, the ground state and two closely lying excited states, are involved in the motion along the torsional reaction coordinate phi. The evolution of the protein-retinal system on these three electronic surfaces has been modelled using the multiple spawning method for non-adiabatic dynamics. We find that, although most of the population transfer occurs on a timescale of 300 fs, some population transfer occurs on a longer timescale, occasionally extending well beyond 1 ps.     

Tautomerism of diazepines fused with pyrimidine rings

The tautomerism of 1,4‐diazepines fused with pyrimidine rings was studied by means of nmr spec‐troscopy, X‐ray analysis and quantum chemical calculations. It was found that in the case of 6,8‐diphenyl‐pyrimido[4,5‐b][1,4]diazepin‐4‐ols (7a ‐ e) the enamine form is more stable than the diimine form. This result is rationalized with the electron‐withdrawing effect of the 4‐hydroxypyrimidine ring and with the formation of intermolecular hydrogen bonds. In contrast to 7a ‐ e , the 6,8‐diaryl‐2,3,4,7‐tetrahydro‐1,3‐dimethyl‐1H‐pyrimido[4,5‐b][1,4]diazepine‐2,4‐diones (9a, c, f) exist in the diimine form.     

Mechanical and thermal characterization of sisal fiber reinforced polylactic acid composites

The advantages of green composites are including, but not limited to their environmental friendly nature, lightweight, reduction of production energy and costs, and recyclability. This work focuses on the mechanical, thermal, and dynamic mechanical properties of biocomposites. For that purpose, biosourced polymers were used, namely polylactic acid (PLA) and sisal fiber, and biocomposites were extruded and then injection molded with different contents of sisal fibers (5%, 10%, 15%). The results show that the increase of the rate of reinforcement improves the mechanical and dynamic mechanical properties of the biocomposites made. By the increase of the sisal fiber content, the degree of crystallinity of the matrix was increased from 47% to 61%, as sisal fibers were acted as a nucleating agent for the PLA.