Judul: Toksisitas dan Aktivitas Antioksidan Ekstrak Daun Pohon Penghasil Gaharu Hasil Inokulasi
Abstrak: Gaharu leaves are expected to contain many secondary metabolic compounds as a response against fungal infection on gaharu-producing trees. This study aimed to determine the phytochemical components, cytotoxic and antioxidant activities of Aquilaria microcarpa and A. malaccensis leaves with and without fungal inoculation. Gaharu leaves were extracted by using methanol. The phytochemical assay of the crude extract revealed the presence of tannins, steroids, phenols, and flavonoids. The toxicity evaluation with brine shrimp showed that all samples were potencial as active ingredient, but only the juvenile leaves of A. microcarpa inoculated by fungi from Papua and Gorontalo had the potency as anticancer due to their LC50 value < 30 μg/mL. Free radical scavenging activity of the extracts against 2,2-diphenyl-1-picrylhydrazyl showed strong antioxidant activities with IC50 value of < 200 μg/mL. The highest antioxidant activity was exhibited by juvenile leaves of A.microcarpa inoculated by fungi from Timor and uninoculated mature leaves of A. malaccensis.
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Judul: Aktivitas Antioksidan Ekstrak Kemedangan Pohon Penghasil Gaharu Hasil Inokulasi Jenis Aquilaria microcarpa dan Gyrinops verstegii
Abstrak: Agarwood is a non-timber forest product commodity which is traded because of its distinctive fragrance. Kemedangan from gaharu was assumed to have secondary metabolites that are potential as antioxidant. This study aimed to investigate the phytochemicals, toxicity and antioxidant activites of kemedangan from Aquilaria microcarpa and Gyrinops verstegii trees with and without inoculation by Fusarium fungi. Phytochemical assay of ethyl acetate and methanol extract revealed the presence of phenolics, flavonoids, triterpenoids, and alkaloids. The toxicity evaluation using brine shrimp lethality test showed that all extracts were potential as bioactive compounds with 50% lethal concentration value ≤1000 ppm. Antioxidant activities which were measured by using 2,2- diphenyl-1-picrylhidrazyl free-radical scavenging method showed that all extracts had antioxidant activities with 50% inhibition concentration value ≤200 ppm except A. microcarpa ethyl acetate extract from inoculated samples with IC50 of 411 ppm.
Keyword: agarwood, antioxidant, Aquilaria, Gyrinops, kemedangan

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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