Biodiesel production from Castor (Ricinus communis) oil was carried out through transesterification using heterogeneous KOH/zeolite catalyst. The aim of this study was to determine the optimum condition of the reaction. The synthesis of the catalyst was initiated through chemical activation of zeolite, followed by the synthesis of KOH/zeolite through ultrasound-assisted method and calcination at 450 o C. Transesterification of castor oil was performed at a temperature of 55, 60 and 65 o C; 5, 6, 7 h contact times; and 50, 60, 70% of catalyst concentration. The result of XRD analysis on natural zeolite indicated the zeolite belong the group mordenite. The addition of KOH to the activated zeolite gave rise to new peaks at 2θ: 31, 36, and 38. In addition, the data from XRF analysis indicated there is an increase of potassium (K) amount in KOH/zeolite compared to the activated one. Based on the GC-MS data of biodiesel produced through transesterification, the optimum yield of methyl ricinoleate was achieved at 55 o C, 7 h contact time and 70 % catalyst concentration. A number of physical properties such as water content and density are reported to have not yet met the SNI standard.

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Vespa is a popular scooter vehicle in Indonesia. The Vespa rider tends to use their wrist in flexion and extension positions while driving, especially when pulling vespa gas, controlling the brakes, and changing the gears. This repetitive movement could affect the suppression of the median nerve and cause the risk of carpal tunnel syndrome. The observational, analytic descriptive design was used to see the relationship between the duration of a Vespa ride and the risk of carpal tunnel syndrome in Vespa riders. 50 respondents were chosen using purposive sampling with inclusion and exclusion criteria in the Vespa Motorbike community of Malang City. A Carpal Tunnel Syndrome questionnaire was used to assess the risk of carpal tunnel syndrome. The Spearman Test was used to examine the relationship between both variables. All statistical analyses were performed using SPSS. The normality test showed the failure of the number of rearing data (p<0,05). The Spearman test revealed that both groups had a significant relationship (p=0,002). We concluded that there is a relationship between the duration of riding and the risk of carpal tunnel syndrome in Vespa riders. Keywords: Duration of riding, Vespa riders, Carpal Tunnel Syndrome

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