Raman study of oriented ZnO thin films deposited by sol-gel method.

ZnO films with preferred orientation along the (0 0 2) plane were successfully deposited by the sol-gel method using Zn(CH3COO)2.2H2O as starting material and inorganic precursor. A homogeneous and stable solution was prepared by dissolving the zinc acetate in a solution of ethanol and monoethanolamine. Thin films are obtained by spin-coating on glass substrates. ZnO films were obtained by preheating the spin-coated films at 300 degrees C for 10 min after each coating and postheating upto 550 degrees C for 2h. The as-deposited films are transformed into mono-oriented ZnO upon thermal treatment. The films consist of spongy particles aggregates with an uniform size and homogenous surface. The films aim to be used in optoelectronic devices. Raman spectroscopy from ZnO films and deposit solutions has been investigated. New Raman results of the deposit solution suggest that Zn-O bond forms first in solution and that these entities play the role of germs initiating the crystallization mechanisms during films annealing. Raman spectra of the annealed films show the presence of a compressive stress within the film structure.

Pattern of uveitis in a referral centre in Tunisia, North Africa.

AIM: To analyse the pattern of uveitis in a referral centre in Tunisia, North Africa. METHODS: The study included 472 patients with uveitis examined at the Department of Ophthalmology of Monastir (Tunisia) from January 1992 to August 2003. All patients had a comprehensive ocular and systemic history, including an extensive review of medical systems. Complete ophthalmic examination was performed in all cases, including best-corrected Snellen visual acuity, slit-lamp examination, applanation tonometry, and dilated fundus examination with three-mirror lens. Standard diagnostic criteria were employed for all syndromes or entities of uveitis. RESULTS: The mean age at onset of uveitis was 34 years. The male-to-female ratio was 1:1.1. Uveitis was unilateral in 282 patients (59.7%) and bilateral in 190 patients (40.3%). Anterior uveitis was most common (166 patients; 35.2%), followed by posterior uveitis (133 patients; 28.2%), panuveitis (100 patients; 21.2%), and intermediate uveitis (73 patients; 15.5%). A specific diagnosis was found in 306 patients (64.8%). The most common cause of anterior uveitis was herpetic uveitis (56 patients; 33.7%). Toxoplasmosis was the most frequent cause of posterior uveitis (51 patients; 38.3%). Intermediate uveitis was most commonly idiopathic (63 patients; 86.3%). Behçet's disease was the most common cause of panuveitis (36 patients; 36%), followed by Vogt-Koyanagi-Harada (VKH) disease (15 patients; 15%). A total of 16 patients (3.4%) suffered from blindness, and 59 (12.5%) from uniocular blindness. CONCLUSIONS: In a hospital population in Tunisia, the most common causes of uveitis were Behçet's disease, herpes simplex infection, toxoplasmosis, and VKH disease.