Linear Representation of Medial-Like Algebras

In this paper we characterize the paramedial, comedial, and coparamedial pairs of quasigroup operations and paramedial, comedial, and coparamedial algebras with the quasigroup operations. Then we characterize paramedial, comedial, and coparamedial algebras with a unit element and an idempotent regular element.     

Wood surface functionalization by means of low-pressure air plasma

Low-pressure plasma treatments in an radio frequency (RF) discharge of air have been used on the surface of wood to stimulate polar function groups onto pine and beach surfaces to enhance the wettability and activation. The effects of plasma treatments on the morphology and wettability of surfaces were characterized by using static contact angle measurements, attenuated total reflection Fourier transform infrared spectroscopy and scanning electron microscopy. A clear increase in the surface energy of the wood surface due to air plasma treatment was observed. The surfaces became highly hydrophilic when woods were exposed for 5 s or longer to the plasma discharge. The wettability of wood surface can be improved when oxygen functionalities were generated, which can be achieved directly in O-containing plasma or via post plasma reaction. A small reduction in the surface energy of the treated wood after 12 days of aging showed that the plasma-induced cross-linking in the surface of the wood was not the dominant phenomenon.     

Theoretical study on the molecular tautomerism of the 3-hydroxy-pyridin-4-one system

3-hydroxy-pyridin-4-one is a parent molecule for the family of hydroxypyridinones that are known in coordination chemistry as efficient metal ions chelators. In this work, relative stabilities of some possible tautomers were investigated using several quantum chemical methods: CBS (complete basis set methods), Gn, DFT (density functional theory), Hartree–Fock and MP2. Performed calculations show that the system under consideration exists as a mixture of two tautomers with comparable energies. Among them, the hydroxypyridinone structure of the studied molecular system seems to be a bit more stable than the o-dihydroxypyridine one, by a few kJ/mol only. Aromaticity and intra-molecular hydrogen bonding are the main effects influencing the stability of the studied tautomeric structures. Consequently, aromatic effects were calculated using several indices of aromaticity: HOMA (harmonic oscillator model of aromaticity), NICS (nucleus independent chemical shift), H, PDI (para delocalisation index), MCI (multi-centre index) and ASE (aromatic stabilisation energy). The strength of possible intra-molecular hydrogen bonds (H-bonds) was determined by means of the AIM (atoms-in-molecules) method and by calculating enthalpies for theoretical reactions that do or do not involve H-bonds. The AIM method was employed to understand how variations in atomic energies influence the stability of different tautomeric structures.     

Entropy as a measure of diffusion

The time variation of entropy, as an alternative to the variance, is proposed as a measure of the diffusion rate. It is shown that for linear and time-translationally invariant systems having a large-time limit for the density, at large times the entropy tends exponentially to a constant. For systems with no stationary density, at large times the entropy is logarithmic with a coefficient specifying the speed of the diffusion. As an example, the large-time behaviors of the entropy and the variance are compared for various types of fractional-derivative diffusions.     

Gravitational collapse with tachyon field and barotropic fluid

A particular class of space-time, with a tachyon field, $\phi $ , and a barotropic fluid constituting the matter content, is considered herein as a model for gravitational collapse. For simplicity, the tachyon potential is assumed to be of inverse square form i.e., $V(\phi )\sim \phi ^{-2}$ . Our purpose, by making use of the specific kinematical features of the tachyon, which are rather different from a standard scalar field, is to establish the several types of asymptotic behavior that our matter content induces. Employing a dynamical system analysis, complemented by a thorough numerical study, we find classical solutions corresponding to a naked singularity or a black hole formation. In particular, there is a subset where the fluid and tachyon participate in an interesting tracking behaviour, depending sensitively on the initial conditions for the energy densities of the tachyon field and barotropic fluid. Two other classes of solutions are present, corresponding respectively, to either a tachyon or a barotropic fluid regime. Which of these emerges as dominant, will depend on the choice of the barotropic parameter, $\gamma $ . Furthermore, these collapsing scenarios both have as final state the formation of a black hole.     

Heavily doped Si:P emitters of crystalline Si solar cells: recombination due to phosphorus precipitation

The measured saturation current density J_0e of heavily phosphorus‐doped emitters of crystalline Si solar cells is analysed by means of sophisticated numerical device modelling. It is concluded that Shockley–Read–Hall (SRH) recombination exceeds Auger recombination significantly; it is caused by inactive phosphorus. This explains the large discrepancies between measured and simulated J_0e values, observed persist‐ently over the last two decades in industrially fabricated Si solar cells. As a consequence, the heavily phosphorus‐diffused emitters still bear a significant potential to contribute to higher Si solar cell efficiency levels, if the amount of inactive phosphorus can be reduced. (© 2014 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Comparison of quasi-steady-state and unsteady-state formulations in a freeze dryer modeling

An unsteady-state model is developed for primary and secondary stages of freeze drying process of skim milk. The results are compared with those obtained from a quasi-steady-state (QSS) formulation. The QSS formulation is not valid where the applied heat load is high. The applied heat load affects on the drying time the most compared to other parameters like chamber pressure and the radiation surface temperature.     

Thermal and Mechanical Properties of Ultra High Molecular Weight Polyethylene Fiber Reinforced High-Density Polyethylene Homocomposites: Effect of Processing Condition and Nanoclay Addition

A new method to prepare single-polymer high-density (HDPE)-ultra high molecular weight polyethylene (UHMWPE) fiber (PE-PE homocomposites) composed and also PE-PE homocomposites containing HDPE organo montmorillonite clay (OMMT) nanocomposites as a matrix (PE nanohomocomposites) was used. Owing to the major importance of fiber impregnation by the matrix and its effect on the adhesion of matrix/fiber and, consequently, the mechanical properties of the composite, a combination of powder impregnation and film stacking methods, utilizing compression molding, were used for manufacturing the PE-PE homocomposites and PE nanohomocomposites. In addition, PE nanohomocomposites with the matrix containing different amounts of nanoclay were prepared to investigate the effect of the clay on the interfacial and mechanical properties of the PE-PE nanohomocomposites. Several different processing conditions were examined to determine the best conditions for manufacturing of the PE-PE homocomposite and PE nanohomocomposites and it was concluded that 40 bar and 10 min of compression molding resulted in the highest overall mechanical properties. The PE-PE homocomposites and PE-PE nanohomocomposites showed identical trends for the relationship between the effects of processing conditions and mechanical properties. Mechanical results demonstrated that clay platelets could increase the interfacial strength by improving physical entanglements between fiber and matrix through better cocrystallization.     

A novel four-component reaction for the synthesis of disubstituted 1,3,4-oxadiazole derivatives

The 1:1 imine intermediate generated by the addition of benzyl amine to cyclobutanone is trapped by (N-isocyanimino)triphenylphosphorane in the presence of an aromatic carboxylic acid leads to the formation of the corresponding iminophosphorane intermediate. Disubstituted 1,3,4-oxadiazole derivatives are formed via intramolecular aza-Wittig reaction of the iminophosphorane intermediate. The reactions were completed in neutral conditions at room temperature. The disubstituted 1,3,4-oxadiazole derivatives, were produced in excellent yields.