A retrospective analysis of complications of treatment of nevus of Ota with the Q-switched Alexandrite (QS Alex) and Q-switched Neodymium: Yttrium-Aluminum-Garnet (QS Nd-YAG) lasers

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Nevus of Ota: a new classification based upon the response to laser treatment

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Carbon fibre-organoclay hybrid epoxy composites: Fracture behaviours and mechanical properties

The fracture resistance and mechanical properties of carbon fiber reinforced composites (CFRPs) containing organoclay-filled epoxy resin are studied. The XRD analysis and TEM examination revealed well-dispersed organoclay in the epoxy matrix displaying a mixture of exfoliation and intercalation. There was a significant improvement in flexural modulus and a marginal reduction in flexural strength of epoxy matrix due to the incorporation of organoclay. The quasi-static fracture toughness of epoxy increased nearly 60\% with the addition of 3wt\% clay, but there was a 45\% drop in impact fracture toughness with 1wt\% clay. When CFRPs were fabricated with the clay-modified epoxy resin, both the flexural modulus and strength of the hybrid composites showed negligible changes due to a few wt\% of organoclay in the matrix. The interlaminar crack growth stability and the corresponding mode I interlaminar fracture toughness of the hybrid composites with organoclay improved substantially compared to those with carbon fibres only. The hybrid composites typically presented rough matrix surface associated with pinning and crack tip bifurcation, whereas the composite made from neat epoxy showed a smooth river line structure which is characteristic of brittle epoxy. The correlation between the composite interlaminar fracture properties and the toughness of modified matrix is discussed

A Retrospective Analysis of Complications in the Treatment of Nevus of Ota with the Q-Switched Alexandrite and Q-Switched Nd:YAG Lasers

Background. Studies on the use of Q-switched alexandrite (QS alex) and QS Nd:YAG lasers in the treatment of nevus of Ota were limited to case reports and small series. There was no study that looked at the complication rate of these systems. Objective. To retrospectively study the complication rate of nevus of Ota patients that were treated with QS alex laser, QS Nd:YAG laser, or a combination of both. Methods. The study was performed in a teaching hospital and a private hospital, where 513 patients with nevus of Ota had been treated since 1993. The 171 patients with 211 treatment sites were evaluated retrospectively following treatment with QS alex laser only (n = 58), QS Nd:YAG laser (n = 105) only, or a combination of both systems (n = 48). Patients were called back to be interviewed and examined by two independent clinicians to look for evidence of complications. Results. Of the treatment sites, 15.3% had hypopigmentation, 2.9% had hyperpigmentation, and texture changes and scarring were seen in 2.9% and 1.9%, respectively. The combined treatment group was associated with a significantly higher risk of complications. Thirteen patients had recurrence of their nevus after complete or near-complete clearance with laser treatment. Conclusion. Hypopigmentation is common after the use of QS laser for lightening of nevus of Ota. This particularly applies when alternate treatment with QS alex and QS Nd:YAG is used. Recurrence is an important issue and must be taken into consideration, especially when children are treated