Temperature dependence of the pitch in chiral lyotropic chromonic liquid crystals

Polarized optical microscopy image of a fingerprint texture for a lyotropic chromonic liquid crystal entering the chiral nematic–isotropic coexistence region. The helical axis is in the plane of the image and the perpendicular distance between the stripes is around 50 μm, half the chiral nematic pitch.

Effect of fly ash particle reinfo rcement on microstructure, porosity and hardness in Al-(Si-Mg) cast composites

The microstructure of cast Al-4Si-Mg reinforcedwith fly ash particles at various particlecontents has been studied. The composites were fabricated by stir casting process andcharacterized by optical microscopy, image analyzer, scanning electron microscopy and hardness measurements. The results showed that particle contents affected to the presence oforosities and hardness of the composites. It was observed that increasing the fly ash contentincrease the porosity in the composites, with the matrix alloy reinforced with 15 wt.% of fly ash particles having the highest porosity and lowest hardness.

The Porous TiNb24Zr4 Alloys with Controllable Porosity Fabricated by Conventional Sintering

In the present study, porous titanium alloys were fabricated successfully by mixing titanium, niobium, and zirconium powder with pore-forming agent of ammonium bicarbonate via conventional sintering method. The pore characteristics, such as pore morphology and distribution, mean pore size and porosity of prepared porous TiNb24Zr4alloy were investigated by optical microscopy, image processing and density determination. It was found that the pore characteristics mainly depended on the shape and size of used ammonium bicarbonate particles in present study. The porosity of the alloys could be tailored by controlling the amount of ammonium bicarbonate addition. The porous TiNb24Zr4alloys were near β type titanium alloys, which consisted mainly of β phase and a little of α phase. The amount of α phase increased in the porous alloys due to segregation caused by the addition of pore-forming agent.

Origin of microaggregates in soils with ferralic horizons

Microaggregates that characterize ferralic soils have been hypothesized to have physical, geochemical and/or biological origins. Despite of many studies, the hierarchy between these processes that form microaggregates has seldom been reported. The objective of this work was to study the genesis of microaggregates in a sequence of Ferralic Nitisols developed on Quaternary red clayey sediments and diabase in Piracicaba (SP), Brazil. This issue was tackled by combining optical microscopy, image analysis, scanning electron microscopy and elemental iron quantifications by X-ray fluorescence. Micromorphological investigations showed three different types of microaggregates: (i) oval microaggregates with well sorted quartz grains in their interior; (ii) oval microaggregates without or with poorly sorted quartz grains in their interior; and (iii) dense polyedric microaggregates. These morphological evidences, together with the elemental iron determinations and scanning electron microscopy, revealed the contribution of more than one process for microaggregate formation: (i) the mechanical action of the mesofauna would form the first type of microaggregates (ii) geochemical and biological processes would form the second type and (iii) the fissuration of the soil matrix by expansion and compression processes would form the third type.