Two Glass Transitions Associated to Different Dynamic Disorders in the Nematic Glassy State of a Non-Symmetric Liquid Crystal Dimer Dopped with gamma-Alumina Nanoparticles

In the present work, the nematic glassy state of the non-symmetric LC dimer -(4-cyanobiphenyl-4-yloxy)--(1-pyrenimine-benzylidene-4-oxy) undecane is studied by means of calorimetric and dielectric measurements. The most striking result of the work is the presence of two different glass transition temperatures: one due to the freezing of the flip-flop motions of the bulkier unit of the dimer and the other, at a lower temperature, related to the freezing of the flip-flop and precessional motions of the cyanobiphenyl unit. This result shows the fact that glass transition is the consequence of the freezing of one or more coupled dynamic disorders and not of the disordered phase itself. In order to avoid crystallization when the bulk sample is cooled down, the LC dimer has been confined via the dispersion of -alumina nanoparticles, in several concentrations.

The durability of different fish cage materials and the pros and cons of cage rotation

The procedures described are standard methods used in the European Union to quantify wood quality. Samples used here were smaller than the standards laid down in the DIN system (12 x 12 x 16 cm) as Litsea is a small tree and planks of the required size are unobtainable. The use of quality sized samples means that the results presented here can be compared with each other but unfortunately not with data in the literature. Wood is dried first at ambient temperature in the shade to reduce moisture content to an even 11-12%. Part of the sample was then oven-dried to 0% moisture content and its specific density determined by weighing a subsample of 128 cm super(3) (4 x 4 x 8 cm). Strength of expansion of the wood is determined as the percentage by which the wood sample can be pulled apart parallel and vertical to the grain before it breaks. Compression and bending strengths and elasticity are measured by compressing, bending and pulling wood sample in a machine specially designedto determine the forces required.