Judul: Aktivitas Antioksidan, Antibakteri, dan Degradasi Biofilm Streptococcus mutans Ekstrak Biji Lada Hitam (Piper nigrum).
Abstrak: Lada hitam diketahui memiliki banyak aktivitas hayati bermanfaat. Kandungan senyawa fenolik, alkaloid, dan minyak atsiri lada hitam berpotensi sebagai antioksidan, antibakteri, dan diduga mampu mendegradasi biofilm Streptococcus mutans. Tujuan penelitian ini adalah menentukan aktivitas antioksidan, antibakteri, degradasi biofilm Streptococcus mutans ekstrak pada pelarut yang berbeda, dan minyak atsiri biji lada hitam. Semua ekstrak dan minyak atsiri aktif sebagai antioksidan, dengan aktivitas terbaik pada minyak atsiri sebesar 139.05 mmol α-tokoferol ekuivalen/g sampel dan lebih baik dibanding butylated hydroxytoluene (BHT) 30.62 mmol α-tokoferol ekuivalen/g sampel. Identifikasi kualitatif senyawa aktif antioksidan dari ekstrak lada hitam dilakukan dengan kromatografi lapis tipis-bioautografi menggunakan pereaksi fosfomolibdat. Ekstrak etil asetat, kloroform, dan etanol memberikan 4-5 pita aktif sebagai antioksidan. Ekstrak dan minyak atsiri lada hitam memiliki aktivitas antibakteri Streptococcus mutans yang rendah. Sebagai degradator biofilm minyak atsiri memiliki persen degradasi tertinggi, yaitu 41% pada konsentrasi bahan uji 2000 μg/mL.
Keyword: alkaloid, fenolik, lada hitam, Streptococcus mutans

Judul: Essential oil of temu hitam (Curcuma aeruginosa Roxb.)„s rhizomes, stems, and leaves as antibacterial toward Streptococcus mutans and biofilm degradator on teeth
Abstrak: Rimpang temu hitam banyak digunakan sebagai antibakteri. Penelitian ini membandingkan kemampuan minyak atsiri rimpang, batang, dan daun temu hitam sebagai antibakteri Streptococcus mutans dan pendegradasi biofilm pada gigi menggunakan metode mikrodilusi. Minyak atsiri diisolasi dengan distilasi uap. Potensi antibakteri terbaik adalah minyak rimpang KHM=konsentrasi hambat minimum=15.63 μg/mL dan KBM=konsentrasi bunuh minimum=1000 μg/mL. KHM rimpang sama dengan tetrasiklin. Setelah difraksionasi dengan kolom maupun kromatografi lapis tipis preparatif, KHM dan KBMnya tidak lebih baik. Senyawa 2,2,5-trimetil-2‟(H)-5‟-6‟-dihidropirano[3‟,4‟,g]indan-1-on diduga paling berperan sebagai antibakteri S. mutans. Kemampuan degradasi biofilm minyak atsiri kasar temu hitam kurang kuat. Minyak atsiri batang lebih baik mendegradasi biofilm (IC50=1347 μg/mL) daripada rimpang dan daun. Setelah difraksionasi, beberapa fraksi minyak atsiri rimpang (F1, F2, dan F3) lebih baik kemampuan degradasinya tetapi IC50 lebih tinggi dari klorheksidin., Rhizomes of temu hitam are widely used as antibacterial. This research compare the potency of essential oil of rhizomes, stems, and leaves of temu hitam as antibacterial toward Streptococcus mutans and biofilm degradator on teeth. The essential oil was isolated by steam distillation. Rhizome‟s essential oil showed good potency as antibacterial with MIC=minimum inhibition concentration=15.63 μg/ml and MBC=minimum bactericidal concentration=1000 μg/ml. MIC of rhizome was same with tetracycline. MIC and MBC of rhizome‟s essential oil was smaller than fraction of column and preparative thin layer chromatography. The 2,2,5-trimethyl-2‟(H)-5‟-6‟-dihydropyrano[3‟,4‟,g]indan-1-one give better potency as antibacterial toward S. mutans. Essential oil of temu hitam was not stronger as biofilm degradator. Stem‟s essential oil was the better essential oil (IC50=1347 μg/mL) to degradate biofilm than rhizome and leave‟s essential oil, but some of fraction of rhizome‟s essential oil (F1, F2, and F3) have better potency than stem‟s essential oil but the IC50 was higher than chlorhexidine. Keywords: Antibacterial, biofilm degradator, essential oil, Streptococcus mutans
Keyword: antibakteri, minyak atsiri, pendegradasi biofilm, Streptococcus mutans

Judul: Analysis of Unequal Income Distribution with Cobb-Douglas Production Function
Abstrak: This paper studies the economic growth model by Moav (2002). Moav model shows the existence of unequal income distribution between low-income with high-income community. That kind of unequal income distribution is caused by uneven distribution of income. On this Moav model, there is one area called the threshold. Threshold becomes a benchmark to determining whether a society is categorized into low- or high- income community. The production function used in this paper is the Cobb-Douglas function. The dynamics of this model is described as difference equation of low-income, threshold, and high-income community. Simulation study on the model is carried out using Maple 13 and Mathematica 7.0 software. Overall, from the observed case, high-income community will reach a stable condition earlier, followed by the threshold, and then the low-income community.
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