Melasma, a commonly acquired hyperpigmentation skin condition, is usually treated with topical agents as the first line of management. This systematic review and meta-analysis aimed to assess the efficacy and safety of azelaic acid versus hydroquinone in treating melasma patients. We conducted a comprehensive search across four online databases (PubMed, Scopus, Web of Science, and Cochrane Library) from the time of their creation until May 28, 2023. We considered randomized controlled studies comparing hydroquinone with azelaic acid for the treatment of melasma patients. We used the Cochrane Risk of Bias tool 2 to evaluate the risk of bias. The mean difference (MD) for continuous variables and the risk ratio (RR) for categorical variables, with a 95% confidence interval (CI) were pooled. Six studies were included, with a total of 673 patients with melasma. The azelaic acid had a lower mean change in melasma area severity index (MASI) than the hydroquinone group [MD= -1.23, 95% CI (-2.05, -0.40), P=0.004]. No difference was observed regarding the improvement via the objective response scale, the reduction in pigmentation, or the adverse events reported. However, despite not being statistically significantly different, there was a trend towards having more good responses in the azelaic acid group. Azelaic acid may be better than hydroquinone in reducing melasma severity (measured by MASI). However, larger studies with long-term follow-up are needed to validate these findings.

Ride comfort has been an important development parameter for transport vehicles starting from early horse carriages with simple leaf spring suspension systems, up to modern vehicles with the state-of-the-art suspension systems. A vehicle without a suspension system will transfer all the disturbances caused by bumps or holes on the road resulting to high acceleration and jerk values at the passenger compartment. Suspension system acts as the cushion of the vehicle when it undergoes road irregularities improving passenger comfort. Softer suspension systems provide better ride comfort via reducing the magnitude of the chassis oscillations however have negative effect on vehicle dynamics considering the fact that they result with loss of traction due to excessive roll motion of the vehicle causing weight transfer from the inner wheels to the outer wheels during cornering manoeuvres. Hence, optimization of suspension system parameters is essential considering both vehicle comfort and dynamics. Similar to all mechanical components, optimization using real hardware is considerably expensive and time consuming. Therefore, model-based optimization is essential to obtain the best performance parameters considering objectives as follows: minimize acceleration magnitude and pitch angle. Within this study a Half Car Model (HCM) for vehicle suspension system is developed in MATLAB / Simulink software and parameters used in the model are tuned for a Sport Utility Vehicle (SUV) using measurements captured via MATLAB Mobile software employed in a mobile phone. A full factorial Design of Experiment (DOE) is developed spanning ± %20 of original values. A regression model is built in Minitab software and it has been showed that optimized parameters result with %3.4 and 9.4% reduction in pitch angle and maximum acceleration values respectively.