Judul: Antibacterial Activity and Identification of Bioactive Compounds from Mangkokan Leaf Extract (Polyscias scutellaria)
Abstrak: Tanaman mangkokan (Polyscias scutellaria) merupakan salah satu tanaman obat Indonesia yang biasanya dimanfaatkan sebagai obat tradisional, tanaman hias, tanaman pagar, dan sumber pangan. Ekstrak daun mangkokan mengandung senyawa dengan aktivitas antibakteri. Penelitian ini bertujuan menguji aktivitas antibakteri ekstrak daun mangkokan, serta mengidentifikasi senyawa bioaktif yang terkandung dalam ekstrak. Ekstraksi daun mangkokan dilakukan menggunakan pelarut metanol, etanol, etil asetat, dan n-heksana. Ekstrak diuji aktivitas antibakteri dan diidentifikasi senyawa bioaktifnya menggunakan GC-MS. Hasil uji antibakteri menunjukkan bahwa ekstrak metanol dan etanol memiliki aktivitas antibakteri terhadap Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, dan Bacillus subtilis. Ekstrak n-heksana hanya memiliki aktivitas antibakteri terhadap E. coli, sedangkan ekstrak etil asetat tidak menunjukkan aktivitas antibakteri. Berdasarkan hasil analisis GC-MS, semua ekstrak daun mangkokan mengandung senyawa bioaktif dengan aktivitas antibakteri. Penelitian lebih lanjut diperlukan untuk menampilkan potensi antibakteri ekstrak daun mangkokan secara lebih baik., The mangkokan plant (Polyscias scutellaria) is one of the Indonesian medicinal plants which are usually used as a traditional medicine, ornamental plant, hedge plant, and food source. Mangkokan leaf extract contain antibacterial activity compounds. This study aims to examine the antibacterial activity of mangkokan leaf extract, as well as to identify the bioactive compounds contained in the extract. Mangkokan leaf extraction was carried out using methanol, ethanol, ethyl acetate, and n-hexane solvents. The extracts were tested for antibacterial activity and the bioactive compounds were identified using GC-MS. The results of the antibacterial test showed that the methanol and ethanol extracts had antibacterial activity against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Bacillus subtilis. The n-hexane extract only had antibacterial activity against E. coli, while the ethyl acetate extract did not show antibacterial activity. Based on the results of GC-MS analysis, all mangkokan leaf extracts contained bioactive compounds which have antibacterial activities. Further research is needed to reveal the antibacterial potential of mangkokan leaf extract.
Keyword: Antibacterial, Bioactive compounds, mangkokan leaf extract

Judul: Aktivitas Antibakteri Ekstrak Daun Sengon (Falcataria moluccana (L) Nielsen) terhadap Bakteri Staphylococcus aureus dan Escherichia coli
Abstrak: Disease by infection is most suffered by people and developed from time to time in medicines. The last research showed that Falcataria moluccana leafs had fitochemical compounds and potential as antibactery. The research aimed to study the antibacterial compounds activity of Falcataria moluccana leafs extract at S. aureus and E. coli with gel diffusion (well method). The leafs used in this research were leaf extract from extraction of aquades, ethanol 70%, ethanol 96%, and ethyl acetate. The concentrations were 50, 100, 150, 200, 250, and 300 mg/mL for each solvents. The result showed that aquades extract could not inhibit the growth of bacteria, while ethyl acetate and ethanol extracts showed antibacterial activity. The largest antibacterial activity showed by ethyl acetate extract at concentration 300 mg/mL with inhibiton areas 6.90 and 4.97 mm for S. aureus and E. coli. This values included in medium category. The result of Analysis of Variance with SPSS 16. program for windows showed that variance of solvents and concentration were significantly difference for inhibition areas.
Keyword: Falcataria moluccana (L) Nielsen, S. aureus, E. coli, antibactery

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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