A new microsporidian parasite, Heterosporis saurida n. sp. (Microsporidia) infecting the lizardfish, Saurida undosquamis from the Arabian Gulf, Saudi Arabia: ultrastructure and phylogeny.

A new microsporidian that infects the lizardfish Saurida undosquamis (Richardson, 1848) that are caught in the Arabian Gulf in Saudi Arabia is described here. This parasite invades the skeletal muscle of the abdominal cavity forming white, cyst-like structures containing numerous spores. The prevalence of the infection was 32·1% (135/420). The spores were oval to pyriform in shape and measured approximately 3·3 µm×2·0 µm. The developing spores were found within parasitophorous vacuoles. In mature spores, the polar filament was arranged into 5 coils in a row. Molecular analysis of the rRNA genes, including the ITS region, and phylogenetic analyses using maximum parsimony, maximum likelihood, and Bayesian inference were performed. The ultrastructural characteristics and phylogenetic analyses support the recognition of a new species, herein named Heterosporis saurida n. sp.

Morphological and ultrastructural description of Pleistophora dammami sp. n. infecting the intestinal wall of Saurida undosquamis from the Arabian Gulf, Saudi Arabia.

Pleistophora dammami sp. n. is described from Saurida undosquamis from the Arabian Gulf in Saudi Arabia. Infection appeared as whitish cysts in the intestinal wall. Cysts ranged in size from 1 to 4 mm. The prevalence of the infection across both fish sexes was 17.5% (24/420). Two kinds of spores were recognized, microspores and macrospores, and each were ovoid in shape. The microspores measured ~2.5 × 2.0 µm in size, while the macrospores measured ~6.0 × 3.0 µm. Ultrastructurally, the parasite did not form xenoma but it formed cysts surrounded by thick cyst wall. All stages of development as meronts, sporonts, sporoblast and spores occurred in the cytoplasm of the host cells within sporophorous vesicles. The stages of development occurred asynchronously and thus all stages were randomly distributed within the cysts. Meronts were elliptical and multinucleated, with unpaired nuclei which constantly divided giving rise to new sporonts. During the transition to sporonts, the border of the meronts increased in thickness to form dense discontinuous cell coat. Later, the sporont divided into sporoblast cells which gradually differentiated the typical organelles of the spores. In mature spores, the polar filament was arranged in 20-24 coils in two rows either side of the posterior vacuole. All ultrastructural and morphological criteria indicate that the described species belongs to the genus Pleistophora.

Adhesion characteristics of solution treated environmental dust.

Environmental dust is modified towards self-cleaning applications under the gravitational influence. Dust particles are collected in the local area of Dammam in Saudi Arabia and they are treated with a dilute hydrofluoric acid solution. The changes in chemical and adhesion characteristics of the dust particles prior and after the solution treatment are analyzed. Force of adhesion and work required to remove dust from hydrophobic and hydrophilic glass surfaces are assessed, separately, for solution treated and collected dust. We show that aqueous hydrofluoric acid solution treatment modifies some dust components while causing the formation of submicron cracks and nano/submicron porous/pillars like textures on the dust particles. The texture generated on dust surfaces after the solution treatment has a great influence on dust adhesion characteristics. Hence, the solution treated dust particles result in lower adhesion on hydrophobic and hydrophilic glass surfaces as compared to that of untreated dust. The gravitational force enables to remove solution treated dust from inclined glass surfaces, which becomes more apparent for hydrophobic surfaces.

Correction: Water droplet on inclined dusty hydrophobic surface: influence of droplet volume on environmental dust particles removal.

[This corrects the article DOI: 10.1039/C8RA10092F.].

Laser processing of Ti6Al4V alloy: wetting state of surface and environmental dust effects.

Laser processing of Ti6Al4V alloy surface, via repetitive pulses, is realized incorporating the nitrogen assisting gas. The texture characteristics of the surface and wetting state are analyzed. The free energy of the laser treated surface is estimated. The influence of the dust particles on the treated and untreated surfaces is examined. The solution formed due to water condensate on the dust particles is evaluated. The adhesion of the mud dried solution on the treated and untreated surfaces is assessed through determining the tangential force required for the removal of the solution from the surface. The findings demonstrate that the high power laser repetitive pulse heating results in formation of the hieratically distributed micro/nano pillars on the workpiece surface. The wetting state of the processed surface remains hydrophilic because of the large gap size between the micro/nano pillars. The free energy of the laser textured surface is similar to that obtained for the TiN coated surfaces, which is because of the nitride compounds developed during the processing. The dried liquid solution strongly adheres at the surface and the force needed for removing the dried liquid solution is almost four times of the friction force at the surface. The liquid solution gives rise to locally scattered shallow pit sites on as received surface. This phenomenon does not occur for the laser treated surface, which is related to the passive layer developed on the surface.

Water droplet on inclined dusty hydrophobic surface: influence of droplet volume on environmental dust particles removal.

A water droplet's behavior on an inclined hydrophobic surface in the presence of environmental dust particles is considered and the droplet's dynamics are analyzed pertinent to self-cleaning applications. A polycarbonate wafer is crystallized using the solution-crystallization method to generate hierarchically distributed micro/nano-sized spherules and pillars on the surface. To improve the wetting state and lower the contact angle hysteresis, functionalized silica particles are synthesized and, later, deposited on the crystallized surface. Environmental dust particles are collected and characterized in terms of elemental composition, size and shape. A high-speed camera is used to monitor a water droplet's behavior on the inclined hydrophobic surface with and without the presence of dust particles. The influence of droplet volume on the dust particle removal rate from the inclined hydrophobic surface is assessed. It is found that the functionalized silica particles deposited on the surface result in a droplet contact angle in the order of 158 ± 2° and contact angle hysteresis of 2 ± 1°. The water droplet mainly rolls on the inclined hydrophobic surface and the sliding velocity remains almost 13% of the transverse velocity of the droplet. Droplet wobbling is influenced by the dust particles and the droplet size; in which case, increasing the droplet volume enhances the droplet puddle thickness on the hydrophobic surface. The cloaking of the droplet fluid onto the dust particles causes mixing of the dust particles with the droplet fluid while enhancing the particle removal from the hydrophobic surface. Increasing the droplet volume slightly enhances the size of the area of the cleaned surface.