Hybrid liquid crystals tetrazolyl and isoxazolyl cinnamates

In this work, a series of isoxazolyl and tetrazolylcinnamic ester hybrid liquid crystals (HLCs) were synthesised and their mesomorphic behaviour was analysed. Cinnamic acid derivatives were prepared by Knoevenagel condensation of malonic acid and arylaldehydes. Five-membered tetrazoles and isoxazoles were prepared by [3 + 2] 1,3-dipolar cycloaddition. Tetrazoles were synthesised by sodium azide addition to arylnitrile, while isoxazoles were synthetised by arylnitrile oxide addition to alkenes to form isoxazolines, followed by MnO₂-oxidation. Tetrazolyltolane compounds were also synthesised and their LC behaviour compared with cinnamic esters. HLCs containing isoxazole rings displayed a large mesophase range with high clearing temperature (T_c), with predominance of smectic mesophases SmA and SmC. The HLCs decomposed upon heating due to their high clearing temperature (>250°C). HLCs with tetrazole rings showed a narrow nematic mesophase range with enantiotropic or monotropic behaviour.     

Isolation and characterization of a novel feather-degrading bacterial strain

Feather waste, generated in large quantities as a byproduct of commercial poultry processing, is almost pure keratin, which is not easily degradable by common proteolytic enzymes. Feather-degrading bacteria were isolated from a Brazilian poultry industrial waste. Among these isolates, a strain identified as kr2 was the best feather-degrading organism when grown on basal medium containing 10 g/L of native feather as a source of energy, carbon, and nitrogen. The isolate was characterized according to morphological characteristics and biochemical tests belonging to the Vibrionaceae family. Keratinolytic activity of this isolate was monitored throughout the cultivation of the bacterium on raw feather at different temperatures. The optimum temperature for growth was about 30°C, at which maximum enzyme and soluble protein production were achieved. The enzyme had a pH and temperature optima of 8.0 and 55°C, respectively.     

HREM analysis of structure and defects in a Σ5 (210) grain boundary in rutile

The structure of a 5 (210) boundary in rutile was investigated by high resolution electron microscopy (HREM). The boundary was stepped with an average inclination of about 5° from the symmetrical (210) plane. The steps were associated with 1/5[210] DSC lattice dislocations accommodating a deviation of about 2° from the exact 5 misorientation of 53.1°, and resulting in a misorientation of 51°. The boundary topography, the location of structural units and the local symmetry were determined using pattern recognition techniques. Flat terraces between steps had a periodic 5 (210) structure which exhibited mirror glide symmetry. Image simulations showed best agreement with experimental images for a model structure with a rigid body shift of 0.21 nm parallel, and a 0.10 nm volume contraction normal to the interface. This structure requires a high density of defects or an excess of Ti ions, presumably of lower oxidation state.     

Microwave assisted regiospecific synthesis of 5‐trifluoromethyl‐4,5‐dihydropyrazoles and—pyrazoles

The regiospecific synthesis of a series of twelve 5‐trifluoromethyl‐4,5‐dihydropyrazoles and ‐pyrazoles from the cyclocondesation reaction of 4‐alkoxy‐1,1,1‐trifluoro‐3‐alken‐2‐ones [F₃CC(O)CH=C(R¹)OR, where R¹ = Me, Et, Pr, iso‐Pr, Bu, iso‐Bu, Ph, H; and R = Me, Et] with phenylhydrazine in toluene by environmentally benign microwave induced techniques is reported. It is shown that under appropriated conditions, the variation of microwave irradiation power leads to 4,5‐dihydropyrazole or pyrazole derivatives. This paper also includes the use of montmorillonite K‐10 as a solid support for the synthesis of pyrazoles under solvent free conditions.