Judul: Potensi antioksidasi bebrapa ekstrak senyawa bahan alam yang berkhasiat sebagai antikanker
Abstrak: This research was conducted to compare antioxidation potency of some extracts from natural materials compound ivhich have anticankr poiency. The natural compounds tested were ex&& of mohkota dewa, d m d k a , sahbung nyawa, temuputih, and tofu whey. Analysis have been done using 200 ppm total an centration for each extract tested. Natural antioxidant vitamin E (a-tocopherol 0 ppm) is used for comparison. The degree of oxidation was measured by $Ilobarbituric acid (TBA) method in vitro.
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Judul: Penentuan aktivitas antioksidan ekstrak mahkota dewa, temu putih, sambiloto dan keladi tikus secara in vitro
Abstrak: Buah mahkota dewa (Phaleria macrocarpa, Boerl), temu putih (Curcuma zeodaria), sambiloto (Andrographis paniculata, Nees), dan keladi tikus (Typhonium flagelliforme) berkhasiat sebagai tanaman obat. Tanaman tersebut berpotensi untuk mengobati kanker dan kandungan senyawa di dalamnya diduga berperan sebagai antioksidan.Penelitian ini bertujuan menentukan daya antioksidan dari tanaman mahkota dewa, temu putih, sambiloto, dan keladi tikus dengan menggunakan metode asam tiobarbiturat. Pada metode ini, asam linoleat dioksidasi dengan udara pada suhu 40 oC selama 8 hari, sehingga membentuk produk malondialdehida. Malondialdehida yang terbentuk akan bereaksi dengan asam tiobarbiturat membentuk produk berwarna merah yang serapannya dapat diukur pada panjang gelombang 532 nm. Potensi antioksidan dari keempat ekstrak tanaman tersebut dilihat dari kemampuannya dalam menghambat proses oksidasi. Daya hambat masing-masing tanaman pada konsentrasi 200 ppm untuk ekstrak akuademineral, air panas, dan etanol secara berturut-berturut sebesar 83,44%, 70,86%, 81,84% (mahkota dewa), 60,21%, 82,74%, 69,28% (temu putih), 81,45%, 81,45%, 67,96% (sambiloto), 68,60%, 63,53 %, 72,17% (keladi tikus), dan 87,01% (vitamin E).Berdasarkan uji statistik Anova dan Duncan potensi antioksidan masing-masing tanaman pada konsentrasi 200 ppm jika dibandingkan dengan vitamin E berbeda nyata pada selang kepercayaan 95%.
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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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