Judul: Seleksi dan Optimasi Aktivitas Biodegradasi Senyawa Piren serta Identifikasi Molekuler Bakteri Laut
Abstrak: Piren merupakan salah satu jenis kelompok senyawa Polisiklik Aromatik Hidrokarbon (PAH) berbobot molekul tinggi sehingga sulit didegradasi di lingkungan. Teknik biodegradasi dengan menggunakan bakteri laut indigenous digunakan sebagai upaya mengurangi polutan piren yang bersifat karsinogenik. Tujuan penelitian ini adalah melakukan seleksi dan optimasi aktivitas biodegradasi senyawa piren oleh bakteri laut serta identifikasi dengan metode 16S rDNA. Hasil penelitian pada uji sublimasi menghasilkan 16 isolat positif yang terbagi menjadi 3 kelompok isolat yaitu 5 isolat berdasarkan perubahan warna, 6 isolat pembentuk zona bening dan 5 isolat pembentuk keduanya. Uji pertumbuhan menyatakan terdapat 4 isolat unggul dalam mendegradasi senyawa piren yaitu isolat LBF-1-0114, LBF-0132, LBF-1-0137, dan LBF-1-0140. Isolat LBF-1-0114 dan LBF-1-0137 mampu mendegradasi senyawa piren secara optimum pada konsentrasi piren 250 ppm. Isolat LBF-1-0132 dan isolat LBF-1-0140 menghasilkan konsentrasi piren optimum 650 ppm. Keempat isolat tersebut menghasilkan konsentrasi sel optimum (OD600nm) sebesar 20. Hasil identifikasi 16S rDNA bakteri laut menyatakan bahwa LBF-1-0114 merupakan Stenotropomonas sp., LBF-1-0132 merupakan Pseudomonas aeruginosa, LBF-1-0137 adalah Halomonas sp., dan LBF-1-0140 merupakan spesies Bacillus statosphericus.
Keyword: piren, optimasi, identifikasi molekuler 16S rDNA

Judul: Optimasi Biodegradasi Senyawa Dibenzotiofen dan Identifikasi Molekuler pada Bakteri Laut.
Abstrak: Tumpahan minyak bumi yang sering terjadi di laut akibat kegiatan ekploitasi merupakan salah satu sumber pencemaran lingkungan. Dibenzotiofen merupakan salah satu komponen minyak bumi yang termasuk zat polutan berbahaya dan sulit terdegradasi di lingkungan. Penelitian ini bertujuan melakukan optimasi biodegradasi senyawa dibenzotiofen dengan parameter konsentrasi dibenzotiofen dan konsentrasi sel serta identifikasi molekuler pada bakteri laut melalui analisis 16S rDNA. Berdasarkan hasil seleksi secara kualitatif melalui uji sublimasi, terdapat 19 isolat bakteri laut yang memiliki kemampuan dalam mendegradasi senyawa dibenzotiofen. Hasil seleksi secara kuantitatif berdasarkan uji pertumbuhan terpilih dua isolat bakteri yang unggul dalam mendegradasi dibenzotiofen yaitu isolat LBF-1-0022 dan LBF-1-0062. Isolat LBF-1-0022 memiliki kondisi optimum dalam biodegradasi senyawa dibenzotiofen pada konsentrasi dibenzotiofen 750 ppm dan konsentrasi sel 30.6 x 108 CFU/mL. Kondisi optimum biodegradasi senyawa dibenzotiofen oleh isolat LBF-1-0062 yaitu pada konsentrasi dibenzotiofen 50 ppm dan konsentrasi sel 40.8 x 108 CFU/mL. Berdasarkan hasil analisis gen 16S rDNA pada bakteri laut, isolat LBF-1-0022 dan LBF-1-0062 teridentifikasi sebagai spesies Stakelama pacifica dan Pseudomonas sp.
Keyword: bakteri laut, dibenzotiofen, minyak bumi

Judul: The Effects of Variance of Interest rate to Variance of Annuity Future Values
Abstrak: Time value of money is a concept that refers to the difference of the value of money due to time difference. The value of money for present time would not be the same as the value of money in the future. The value of money for present time is called as Present Value (PV) of the money and the value of money for future time is called Future Value (FV) of the money. Determination the value of money, for present and future time, depends on the time and rate of return. The value of money is determined by several factors such as inflation, fluctuation of interest rates, and government policy in securities and taxation. Due to fluctuation of the value of money we need a FV formulation, it is useful for knowing whether an investment can be profitable or not, and this information is useful also in budget analysis. Annuity is defined as a series of payments made for a specific period. The payment, fixed or varied, can be made at the beginning or at the end of the period. Annuity paid at the beginning of the period is called annuity-due and annuity paid at the end of the period is called immediate annuity-certain. The accumulated value of the annuity after few years later is called as a final value or a future value. Burnecki et al. (2003) have discussed about the FV of a fixed-rate annuity in which payments are made according to the arithmetic or geometric series. They have also examined FV for annuities in which payments are made according to arithmetic or geometric series with random rates of interest. This paper examines FV for annuity-due in which payments are made according to arithmetic or geometric series with interest rates as a random variable, which is normal distribution ,  . Future value formula is expressed in recursive form. FV for annuity-due which payments are made according to the arithmetic or geometric series with random rates of interest is calculated by theoretical way and simulation way. The random rates of interest is denoted as k k i  i  , where k i an independent random variable; i is a constant and k  is a random variable which has normal distribution ,  . By using the determined parameters, a sequence of random rates of interest are generated for theoretical calculation. Meanwhile for the simulation, the random rates of interest is generated 1000 times for the simulation. The generated data give mean value, variance, and standard deviation. Moreover, error of mean value, variance, and standard deviation from the theoretical and simulation results are calculated. Error calculation uses Symmetric Mean Absolute Percentage Error (SMAPE). The smaller the value of SMAPE is the more accurate the simulation. The interest rate variances are varied from 0.000036 to 0.0001 to study the relationship between variance of rates of interest and variance of future value. The theoretical and simulation results show that when the variance of random rates of interest increases, then the variance of FV increases linearly. FV of the annuity-due in
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