Judul: Ability of Bacillus altitudinis Bacteria in Degrading Anthracene Compound.
Abstrak: Hidrokarbon aromatik polisiklik (PAH) merupakan senyawa toksik yang bersifat karsinogenik dan mutagenik sehingga sangat berbahaya jika terdapat di lingkungan. Salah satu jenis PAH yang digunakan dalam penelitian ini adalah antrasena. Biodegradasi merupakan salah satu metode yang dapat digunakan untuk menangani PAH dengan memanfaatkan bakteri. Bakteri yang digunakan dalam penelitian adalah Bacillus altitudinis yang diisolasi dari tanah tercemari minyak bumi. Penambahan alkilbenzena sulfonat linear 0.04% dapat meningkatkan kemampuan bakteri dalam mendegradasi antrasena. Parameter yang diamati adalah rapatan optis, total plate count (TPC), pH, dan analisis menggunakan kromatografi gas-spektrometer massa (GCMS). Hasil pengamatan menunjukkan bahwa selama 28 hari kultivasi, terjadi perubahan pH dari 6 menjadi 8, larutan bertambah keruh, pertumbuhan optimum bakteri terjadi pada 0.4 satuan absorbans, nilai TPC naik dari 0.32×106 cfu/mL menjadi 1.53×106 cfu/mL, dan analisis antrasena setelah 28 hari menggunakan GCMS menunjukkan penurunan tinggi puncak dari hari ke-0 ke hari ke-28 sebesar 62.51%., Ability of Bacillus altitudinis Bacteria in Degrading Anthracene Compound.
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Judul: Perubahan Struktur Fenantrena Selama Proses Biodegradasi oleh Bakteri Bacillus altitudinis
Abstrak: Polycyclic aromatic hydrocarbons (PAHs) are toxic, mutagenic, and carcinogenic pollutants that are present in environment. Some bacterial species have ability to metabolize these compounds and use them as energy sources for their growth. Bacillus altitudinis was used to degrade phenanthrene, a three-ring aromatic PAH. The maximum degradation rate (14%) was obtained when Bacillus altitudinis was cultured for 28 days after the addition of 50 ppm phenanthrene to the liquid medium. Furthermore, the degradation was affected by addition of Tween 80 as surfactants. The observation parameters were total plate count (TPC) and pH. The value TPC increased for 28 days cultivation and pH value increased too from 6 to 8 during the 28 days cultivation. The mechanism of degradation was determined through identification of metabolites, the possible pathway of phenanthrene degradation is via phthalic acid. It has been proofed by a mass spectrum of phthalic acid at retention time of 7.607 with match quality of 72.
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Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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