Judul: Profil Metabolit Volatil Rimpang Temulawak (Curcuma xanthorrhiza Roxb.) yang Dipanen pada Waktu Berbeda.
Abstrak: Yield and composition of secondary metabolites in plants can be affected in many factors, such as harvesting time in a day. Metabolite profiling necessary to explain the influence of harvesting time in a day in volatile metabolites composition of temulawak essential oil. GC-MS analysis used to distinguish the changes in volatile metabolites of temulawak essential oil at different harvesting time. The aims of this research is to explain the influence of harvesting time in composition volatile metabolites temulawak essential oil and their correlation with their bioactivity as antioxidant. A total of 25 volatile compound were identified by GC-MS analysis. The major volatile component in both harvesting time are α- cedrene, α-curcumene, and xanthorrhizol with m/z 204, 202, and 218. The in vitro antioxidant activity was investigated with radical DPPH scavenging assay, ascorbic acid was employed as positive control. The result showed that temulawak essential oil has an antioxidant property, with the IC50 of 3.24x109 ppm in morning and 1.15x1013 ppm in afternoon harvesting time. The essential oil showed radical scavenging, but lower than ascorbic acid. There is no significant different in composition of volatile metabolite and radical scavenging activity of temulawak essential oil with different harvesting time in α=0,05.
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Judul: Pengaruh Variasi Pelarut dan Waktu Ekstraksi Rimpang Temulawak terhadap Total Fenolik, Flavonoid, dan Aktivitas Antioksidan
Abstrak: Temulawak (Curcuma xanthorrhiza) mengandung senyawa metabolit sekunder seperti fenolik dan flavonoid yang berpotensi sebagai antioksidan. Senyawa metabolit sekunder yang banyak ditemukan dalam temulawak adalah kurkuminoid yang tergolong dalam senyawa polifenol. Maserasi merupakan metode sederhana untuk mengekstrak senyawa metabolit sekunder dari tumbuhan. Selama prosesnya, jenis pelarut dan waktu maserasi menjadi faktor penting yang dapat memengaruhi hasil ekstraksi. Penelitian ini bertujuan untuk menganalisis pengaruh pelarut (akuades, etanol 50%, metanol 50%, dan aseton 50%) dan waktu ekstraksi (12, 24, 36, dan 48 jam) terhadap kadar total fenolik, total flavonoid, dan aktivitas antioksidan. Hasil pengujian menunjukkan bahwa etanol 50% memberikan hasil terbaik dengan kadar fenolik 36,29 mg GAE/g, flavonoid 66,96 mg QE/g, dan aktivitas antioksidan (metode CUPRAC) 117,13, Temulawak (Curcuma xanthorrhiza) contained secondary metabolite compounds such as phenolics and flavonoids with potential antioxidant activity. The most abundant secondary metabolite compound found in temulawak was curcuminoid. Maceration was a simple method for extracting secondary metabolite compounds from plants. During maceration, the type of solvent and the maceration time were crucial factors that affected the test results. This study aimed to analyze the effect of solvent (aquadest, 50% ethanol, 50% methanol, and 50% acetone) and extraction time (12, 24, 36, and 48 hours) on total phenolics, total flavonoids, and antioxidant activity. The results showed that 50% ethanol yielded the highest phenolic content (36,29 mg GAE/g), flavonoid content (66,96 mg QE/g DW), and antioxidant activity (CUPRAC method) of 117.06
Keyword: antioxidant, phenolic, flavonoid, solvent, time

Judul: Construction of Strongly Optimal Binary Linear Code with Minimum Distance 9 and 11
Abstrak: A binary linear code of length n over q F is a subspace of n q F . A code has three parameters that attached to it, namely length, dimension, and minimum distance. A code with length n, dimension k and minimum distance d is often called [n, k, d ]-code. Usually, when two parameters are given, then we want to find a code that has the best value for the last parameter. Based on Gilbert- Varshamov bound, if a [n, k, d ]-code exists and can not be expanded, we call it a strongly optimal code. In this paper, we construct strongly optimal code with minimum distance 9 and 11. In constructing the code, we created a theorem and algorithm based on Gilbert-Varshamov bound before we implement the algorithm to MAPLE programming language. Because of computational limitations, the program can only construct up to k = 10 for d = 9 and k = 12 for d = 11.
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