ABSTRACT
In the present study, different amounts of graphene nanosheets (GNSs) were added to the 4043 aluminum alloy powders by using the mechanical alloying method to produce the composite filler wires. With each of the produced composite filler wires, one all-weld metal coupon was welded using the gas tungsten arc (GTA) welding process. The microstructure, mechanical properties and fracture surface morphology of the weld metals have been evaluated and the results are compared. As the amount of GNSs in the composition of filler wire is increased, the microstructure of weld metal was changed from the dendritic structure to fine equiaxed grains. Furthermore, the tensile strength and microhardness of weld metal was improved, and is attributed to the augmented nucleation and retarded growth. From the results, it was seen that the GNSs/Al composite filler wire can be used to improve the microstructure and mechanical properties of GTA weld metals of aluminum and its alloys.
ABSTRACT
BACKGROUND AND OBJECTIVE: Succinylcholine administration, laryngoscopy and tracheal intubation are followed by increased intraocular pressure. Various premedications have been advocated for preventing increases in intraocular pressure, especially in patients undergoing surgical repair of open globe due to penetrating eye trauma. Results of studies in this area have been controversial. METHODS: In this double-blind study, three groups of 70 patients receiving sufentanil, lidocaine and placebo 90 s prior to intubation were evaluated and compared for intraocular pressure changes following succinylcholine administration, laryngoscopy and tracheal intubation. RESULTS: Mean intraocular pressure measured 2 and 3 min after succinylcholine administration in groups receiving sufentanil and lidocaine was significantly lower than in the placebo group. Mean intraocular pressure changes in the three groups were -1.84, -2.03 and +2.82 mmHg, respectively in minute 2; -4.78, -4.73 and +1.35 mmHg, respectively in minute 5. There was a significant intraocular pressure decrease in the sufentanil and lidocaine groups, compared to the placebo group. The eye surgeons' satisfaction was also significantly higher with the sufentanil and lidocaine groups. CONCLUSION: Previous studies have yielded controversial results as to the effect of sufentanil and lidocaine in preventing intraocular pressure following succinylcholine administration, laryngoscopy and tracheal intubation. The present study affirms the preventive effect of these drugs on intraocular pressure increase.
