RESUMEN
There is increasing demand to functionalize meso- and nanoporous materials by coating and make the porous substrate biocompatible or environmentally friendly. However, coating on a meso-porous substrate poses great challenges, especially if the pore aspect ratio is high. We adopted the pulsed laser deposition (PLD) method to coat Ni(3)Al-based meso-porous membranes, which were fabricated from a single-crystal Ni-based superalloy by a unique selective phase dissolution technique. These membranes were about 250 µm thick and had channel-like pores (â¼200 nm wide) with very high aspect ratio. Two different coating materials, i.e. diamond-like carbon (DLC) and titanium, were used to coat these membranes. High energy C or Ti ions, produced in the plasma plume by the PLD process, penetrated the channel-like pores and deposited coatings on the pore walls deep inside the membrane. The thickness and the quality of coatings on the pore walls were examined using the dual-beam system. The coating thickness, of the order of 50 nm, was adherent to the pore walls and was quite uniform at different depths. The carbon and the Ti deposition behaved quite similarly. The preliminary experiments showed that the PLD is an adequate method for coating fine open cavities of complex geometry. Simulations based on stopping and the range of ions in matter (SRIM) calculations helped in understanding the deposition processes on pore walls at great depths.
RESUMEN
A method which is able to produce different types of nano-structured materials, namely nano-particles, nano-structured surfaces and nano-porous membranes, from two-phase metallic alloys is reviewed. The new process first establishes nano-structures in the bulk alloy and then separates them by selective phase dissolution. Variation in processing makes it possible to produce different types of nano-structure even from the same alloy. The process can be applied to many different alloy systems. An overview is presented emphasizing the versatility of the process with examples of different nano-structure types that can be produced. Further, the new method is discussed in relation to similar processes (specifically, electrochemical processes) which have been used for nano-structure synthesis.
RESUMEN
Oral leucoplakia was predominantly seen in elderly age group. Addiction to tobacco was observed in majority of patients (80.8%). Clinically commonest site of involvement was buccal mucosa (67.33%), followed by labial mucosa (13.86%). Majority of patients (57.35%) were having homogenous type of leucoplakia, followed by verrucous variety (25%). 26-48% cases were also having oral submucous fibrosis. Histologically various combinations of hyperkeratosis, hyperorthokeratosis and acanthosis were observed in 77.93% of cases. Dysplastic lesions were reported in 17.65% cases. In 80% of dysplastic lesions, band like infiltrate of mononuclear cells in subepithelial zone was seen. Malignant transformation was noticed in 2.94% cases. Excellent therapeutic results were obtained by cryosurgery. In resistant cases good results were observed with high dosage of vitamin A.