Hyper-para-Kähler Lie algebras with abelian complex structures and their classification up to dimension 8

Hyper-para-Kähler structures on Lie algebras where the complex structure is abelian are studied. We show that there is a one-to-one correspondence between such hyper-para-Kähler Lie algebras and complex commutative (hence, associative) symplectic left-symmetric algebras admitting a semilinear map \(K_s\) verifying certain algebraic properties. Such equivalence allows us to give a complete classification, up to holomorphic isomorphism, of pairs \(({\mathfrak g},J)\) of 8-dimensional Lie algebras endowed with abelian complex structures which admit hyper-para-Kähler structures.     

The effect of various compatibilizers on thermal,mechanical, and morphological properties of polystyrene/polypropylene blends

The effects of various compatibilizers on thermal, mechanical and morphological properties of 50/50 polypropylene/polystyrene blends were investigated. Various compatibilizers, polystyrene-(ethylene/butylenes/ styrene) (SEBS), ethylene vinyl acetate (EVA), polystyrene-butylene rubber (SBR) and blend of compatibilizers SEBS/PP-g-MAH, EVA/PP-g-MAH, and SBR/PP-g-MAH were used. Differential scanning calorimetry, thermogravimetric analysis, wide-angle X-ray scattering, scanning electron microscopy, microhardness, and Izod impact strength were adopted. It was found that the influence of various compatibilizers was appeared on all the properties studied. The properties of the blends compatibilized with SEBS, EVA, and SBR are very distinct from those of blends compatibilized with blend of compatibilizers. Results show that compatibilized blends with the blend of compatibilizers EVA/PP-g-MAH, SBR/PP-g-MAH, and SEBS/PP-g-MAH or SBR were relatively more stable than the uncompatibilized blend and blend compatibilized with SEBS or EVA. The compatibilizer does not only reduce the interfacial tension or increase the phase interfacial adhesion between the immiscible polymers, but greatly affects the degree of crystallinity of blends.

     

Gelatin films with very high surface hardness

Microhardness (H) of gelatin dry cast films was measured in the 100–250°C range. A strong H increase with temperature from 330 MPa up to 450 MPa was observed in the first cycle. The H values reached in the subsequent cycles are higher than those obtained in the preceding ones, surpassing the hardness of all commercial synthetic polymers and soft metals. Results are discussed in terms of crosslinking between side-chain reactive groups.     

Photochemical reactions. VI. Photo-Beckmann rearrangement with vinyl migration. Preliminary communication

The carefully controlled UV. irradiation of 3-hydroxyimino-Δ⁴- and 3-hydroxyimino-Δ⁴, Δ⁶-steroids yield as a result of vinyl and alkyl migration, lactams besides products expected.     

Cross-Coupling Reactions of Monosubstituted Acetylenes and Aryl Halides Catalyzed by Palladium on Charcoal

A convenient procedure for the Pd(O) catalyzed cross-coupling of monosubstituted acetylenes with aryl halides, in which palladium on charcoal serves as the source of the noble metal is described.     

Application of matrix solid-phase dispersion to the propham and maleic hydrazide determination in potatoes by differential pulse voltammetry and HPLC

The application of the matrix solid-phase dispersion (MSPD) process as sample treatment in connection with the electrochemical detection is studied for the first time. For this purpose, a novel methodology is introduced for the extraction of propham and maleic hydrazide herbicides from potatoes samples based in the MSPD process prior to their electrochemical detection. Potato samples disruption was done by blending them with C₈ bonded-phase and selective herbicide extraction was achieved by successive treatment of the blended with 50 mM phosphate buffer pH 7.4 (for maleic hydrazide) and methanol (for propham). The extraction procedure efficiency was estimated using differential pulse voltammetry in potato samples spiked with the herbicides yielding recovery values of 98% and 68% for propham and maleic hydrazide, respectively. No significant adverse effect of the MSPD process was observed on the herbicides electrochemical signals. For comparison, recovery studies using HPLC with UV detection were carried out and a good correlation in the results obtained by using both techniques was observed.     

Synthesis, characterization, and properties of subporphyrazines: a new class of nonplanar, aromatic macrocycles with absorption in the green region

Novel subphthalocyanine analogues that display strong absorption in the green region have been synthesized by using a boron template cyclotrimerization of maleonitrile derivatives. The spectroscopic properties of these macrocycles indicate that, like subphthalocyanines, they have 14 pi electrons and are aromatic compounds with a conical shape. The removal of the three fused benzene rings from the subphthalocyanine skeleton produces a 75-80 nm blue shift of the Q-band and a slight lowering of the absorption coefficients for this band. In addition, the reduction of the pi system from 18 to 14 electrons that accompanies progression from porphyrazines to subporphyrazines causes a hypsochromic shift of the Q-band of around 100 nm. Subporphyrazines that are peripherally functionalized with six thioether chains, and in which the sulfur atoms are attached directly to the pyrrole moieties, exhibit optical features that may be explained in terms of the extension of pi conjugation over the six thiolene groups, as well as strong pi donation from the sulfur lone pairs to the macrocycle. These two effects are quantitatively and qualitatively very similar to those observed for porphyrazines that possess the same type of substitution. In addition, the mesomorphic behavior at low temperatures of a macrocycle that is substituted with six thiododecyl chains was demonstrated by using differential scanning calorimetry and optical polarising microscopy.