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: Isolasi dan Identifikasi Kapang Endofit Mangrove Penghasil Metabolit Sekunder dan Kajian Metabolitnya sebagai Antimikroba Alami pada Pangan
Abstrak: Mangrove dikenal memiliki beberpa manfaat dalam pengobatan tradisional. Kapang Endofit mangrove berpotensi menghasilkan metabolit sekunder yang bisa dimanfaatkan seperti antibakteri. Antibakteri merupakan senyawa yang banyak diaplikasikan industri sebagai bahan baku produk dalam sektor makanan ataupun kesehatan. Tujuh belas isolat kapang endofit berhasil diisolasi dari 7 spesies mangrove yang berasal dari Berau, Kalimantan Timur, Indonesia. Tiga isolat yang diekstrak dari isolat kapang OJ-B, OJ-Bu, dan 6Xg-Bh memiliki aktivitas antibakteri tertinggi dengan zona hambat 9.63-25.4 mm dan dengan nilai MIC (minimum inhibitory concentration) dan MBC (minimum bactericidal concentration) sekitar 0.625-5 mg/mL dan 2.5-10 mg/mL. Identifikasi kimia dengan LC-MS (liquid chromatography-mass spectrometry) menunjukkan beberapa senyawa yang berpotensi sebagai antibakteri yaitu beauvericin, betaine, proline, adenosin, L-phenylalanine, quinoline, cyclo(phenylalanyl-prolyl), dan borrelidin. Sedangkan identifikasi spesies kapang dengan metode molecular berhasil mengidentifikasi tiga spesies yaitu Diaporthe phaseolorum, Fusarium proliferatum dan Phomopsis sp. Hasil penelitian ini menunjukkan bahwa kapang endofit dari beberapa spesies mangrove di Berau Kalimantan Timur mampu menghasilkan senyawa bioaktif sebagai antibakteri.
Keyword: Acanthus ilicifolius, Antimikroba, Isolasi, Kapang Endofit, Mangrove

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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