Plasma beam alignment of liquid crystal with improved alignment stability [LCD manufacture]
A method of plasma beam treatment providing liquid crystal (LC) aligning substrates of improved alignment stability is described. In this method the aligning substrates are obliquely treated with a plasma flux containing alignment and passivation agents simultaneously. This method is applicable for the substrates of organic and inorganic origin. During this treating process, good pretilt angle stability and alignment quality are much promised.
Planar and tilted uniform alignment of liquid crystals by plasma-treated substrates
We describe a new aligning technique that yields uniform planar or tilted orientation of a nematic liquid crystal at different organic and inorganic substrates. The method is based on the oblique irradiation of an aligning substrate with a partially collimated flux of accelerated plasma. The sheet-like plasma flux is produced by an anode layer thruster with a race track geometry of the discharge channel. For liquid crystals with a positive dielectric anisotropy the technique produces two modes of uniform alignment: (1) with the easy axis in the incident plane of the plasma beam; (2) with the easy axis perpendicular to the plane of incidence. Mode 1 transforms into mode 2 as the irradiation dose increases. In mode 1, the pretilt angle can be controlled by changing the parameters of irradiation such as incidence angle, current density and particle energy. In mode 2, the pretilt angle is zero (planar alignment). The azimuthal anchoring coefficient is relatively weak (W a∼10−6 J m−2) for the first type of alignment and strong (W a≥10−4 J m−2, comparable to rubbed polymer substrates) for the second type. The two-mode alignment feature can be used to control alignment properties and to create alignment patterns. The method is free from the usual shortcomings of the traditional rubbing technique. We discuss possible mechanisms of the two-mode alignment and show that plasma-induced modifications of the substrate topography might be an important factor in liquid crystal alignment.
The infection process, sporulation and survival of Alternaria helianthi on sunflower
SUMMARY 
 
Electron microscopy was used to study the infection of sunflower leaves by Alternaria helianthi. Conidia germinated by producing one to many germ tubes which grew across the leaf surface before forming appressoria. The fungus directly penetrated its host through the cuticle and epidermis. Entry into the host through wounds and stomates was also observed. Extracellular sheaths were found to be associated with germ tubes and intercellular hyphae of A. helianthi. Conidiophores developed through collapsed stomates, from leaf veins, trichomes and also from mycelium growing across the host leaf surface. Microcylic conidia were produced directly from parent conidia under certain conditions. Studies using a volumetric spore trap showed that the airborne spore concentration followed a distinct periodicity with peaks occurring between 0900 and 1100 h each day. Laboratory studies showed that safflower, noogoora burr and bathurst burr could serve as alternative hosts for A. helianthi. The pathogen was readily isolated from sunflower crop debris from a diseased crop that had been harvested 1 yr earlier.