Judul: Pengaruh Perebusan Terhadap Aktivitas Biologis Dan Kandungan Fenolik Buah Takokak (Solanum Torvum Swartz)
Abstrak: Buah takokak (Solanum torvum Swartz.) biasa dikonsumsi masyarakat Indonesia sebagai pangan pendamping. Selain itu, buah takokak sering pula digunakan sebagai obat tradisional, salah satunya sebagai obat diabetes mellitus. Penelitian ini bertujuan untuk mengetahui total fenol, aktivitas antioksidan, dan aktivitas alfa glukosidase inhibitor dari ekstrak metanol, fraksi air, butanol, kloroform, dan n-heksan buah takokak segar dan rebus. Hasil penelitian menunjukkan fraksi air buah takokak segar memiliki kandungan total fenol tertinggi yaitu sebesar 107.00 μg GAE/mg ekstrak. Sementara fraksi buah takokak rebus dengan kandungan total fenol tertinggi adalah fraksi butanol, yaitu sebesar 129.08 μg GAE/mg ekstrak. Perebusan meningkatkan kandungan total fenol secara signifikan pada taraf signifikansi 5% kecuali pada fraksi air. Uji aktivitas antioksidan DPPH menunjukkan fraksi dengan aktivitas antioksidan tertinggi adalah fraksi heksan takokak segar dan fraksi air takokak rebus dengan nilai IC50 masing-masing sebesar 82.05 mg ekstrak/mL dan 24.58 mg ekstrak/mL. Perebusan meningkatkan aktivitas antioksidan secara signifikan pada taraf signifikansi 5%. Uji penghambatan alfa glukosidase menunjukkan fraksi butanol dan kloroform buah takokak segar memiliki penghambatan alpha glukosidase masing-masing mencapai 56.40% dan 72.61%. Sementara fraksi takokak rebus yang memiliki aktivitas penghambatan adalah fraksi butanol sebesar 80.01%. Aktivitas penghambatan alfa glukosidase pada buah takokak rebus berbeda nyata pada taraf signifikansi 5% kecuali pada fraksi n-heksan. Uji statistik Pearson correlation pada ketiga data menunjukkan korelasi yang cenderung lemah antara kandungan total fenol dengan baik aktivitas antioksidan aktivitas maupun penghambatan alfa glukosidase pada sampel segar dan rebus.
Keyword: buah takokak, alfa glukosidase inhibitor, antioksidan, total fenol, diabetes mellitus

Judul: Aktivitas Antioksidan Ekstrak Buah Takokak (Solanum torvum Swartz.)
Abstrak: Turkey berry fruit (Solanum torvum Swartz.) is one of indigenous fruit vegetables that widely used in traditional medicine. Because, it has some functional properties such as antioxidant, antibacterial, antifungal, and antiviral. The functional properties come from the activity of some phytochemicals compound that Turkey berry fruit contents, such as phenolics and non phenolics. This research was designed to identify the chemical content of Turkey berry fruit, change content, and antioxidant activity of crushed form. The research method consisted of treatment phase of fresh Turkey berry fruit through the destruction process and extraction phase of Turkey berry fruit powder with organic solvents (methanol, etil acetat, and hexane). The results showed that methanol extract of both whole and crushed Turkey berry fruit, contains alkaloids, flavons, tannins, and saponins. The etil acetat and hexan extracts of both whole and crushed form, contains alkaloids, flavons, terpenoids, and saponins. Thus, the presence of phenolic compounds in Turkey berry fruit can be affected by Phenylalanin Ammonia Lyase (PAL) activity, but not always influenced by the total anthocyanin. In addition, the antioxidant activity (DPPH assay) between whole and crushed Turkey berry fruit extracts is not significantly different (p>0.05) by t-test. It was demonstrated that the destruction process has a little affecting to the presence of phenolic compounds that act as antioxidants, such as anthocyanin. However, the antioxidant activity of extracts is not always determined from total phenolic, but depending on the ability of -OH group to donate H atoms and to bind with free radicals rapidly. The antioxidant activity of Turkey berry fruit extract was slightly be affected by ascorbic acid (vitamin C) compound.
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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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