Judul: Aktivitas Antibakteri dan Antioksidan Ekstrak Air, Etanol, dan N- heksana Sayur Hitam (Asystasia sp.) Asal Kabupaten Dogiyai-Papua.
Abstrak: The black vegetable (Asystasia sp.) plants has been used by people in Papuan as vegetable and has been known to heal wounds. The purpose of this study was to identify the content of phytochemicals, antibacterial and antioxidant from black vegetable. The black vegetable extracted with water, 70% ethanol, and n-hexane solvent. Antioxidant activity of black vegetable extracts were determined by DPPH method and antibacterial activity tested by paper disc method against Escherichia coli (Gram negative) and Staphylococcus aureus (Gram positive). The result phytochemicals showed that the black vegetable by water, ethanol 70% and n-hexane extracts contained flavonoid, saponin, tannin and steroids. Antibacterial test results showed that the extract do not have any antibacterial activity against E.coli and S. aureus. The analysis of antioxidant activity showed that the IC50 value of boiling (water), heating (water), n-hexane, without heating (water) and ethanol 70%, respectively for 1286.894 ppm, 3391.667 ppm, 1098.667 ppm, 228 842 ppm and 263.117 ppm. The conclusion, black vegetable is do not have antibacterial activity and has a weak antioxidant activity.
Keyword: E. coli. S. aureus, black vegetable, antioxidant, antibacterial

Judul: Aktivitas Antioksidan dan Sitotoksisitas Ekstrak Bawang Hitam (Allium sativum)
Abstrak: Bawang hitam adalah hasil dari proses pemanasan dan pencoklatan bawang putih, dan merupakan salah satu dari bahan olahan di Indonesia yang dapat dimanfaatkan sebagai sumber antioksidan untuk mengatasi penyakit degeneratif. Penelitian ini bertujuan melakukan ekstraksi bawang hitam yang dikeringkan untuk selanjutnya diuji aktivitas antioksidan dan sitotoksisitasnya. Bawang hitam dikeringkan dan diekstraksi dengan menggunakan 4 jenis pelarut yaitu etanol 30%, 70%, 96% dan akuades. Uji kadar air dan penghitungan rendemen dilakukan untuk mengetahui kualitas sampel. Aktivitas antioksidan ekstrak ditentukan menggunakan uji DPPH dengan vitamin C sebagai kontrol positif, dan sitotoksisitas ditentukan menggunakan uji BSLT. Hasil uji menunjukkan bawang hitam memiliki kadar air sebesar 9.16% dengan rendemen terendah dari pelarut etanol 96% sebesar 22.79 % dan rendemen tertinggi dari pelarut etanol 70% sebesar 45.34%. Ekstrak bawang hitam dengan pelarut akuades memiliki nilai IC50 dan LC50 terendah dibandingkan dengan ekstrak lainnya, dengan nilai IC50 sebesar 4.58 ppm dan nilai LC50 sebesar 758.57 ppm.
Keyword: antioksidan, bawang hitam, ekstrak, sitotoksisitas

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.
Keyword: