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: Uji Aktivitas Antioksidan Fungi Endofit Aquilaria crassna Tanaman Penghasil Gaharu.
Abstrak: Tingginya permintaan produk gaharu sebagai obat-obatan terutama sebagai antioksidan menyebabkan permintaan pasar terhadap gaharu semakin tinggi. Hal ini mengakibatkan eksploitasi tanaman penghasil gaharu sehingga terjadinya kepunahan dan kelangkaan terhadap tanaman penghasil gaharu, terutama pada jenis Aquilaria spp. Fungi endofit diharapkan menjadi alternatif karena mampu menghasilkan metabolit sekunder yang mirip dengan inangnya. Penelitian ini bertujuan mendapatkan ekstrak teraktif antioksidan dari dua isolat fungi endofit tanaman penghasil gaharu Aquilaria crassna. Ekstrak etil asetat kasar difraksinasi menggunakan ekstraksi cair-cair dan diperoleh 4 fraksi, yaitu fraksi n-heksana, fraksi klorofom, fraksi etil asetat, dan residu (fraksi metanol). Hasil ekstak fraksinasi didapatkan isolat P1B1C dengan ekstrak n-heksana merupakan isolat dengan potensi antioksidan kuat dengan IC50 sebesar 79.86 μg/mL dengan total fenol sebesar 23.32 mg Ekuivalen Asam Galat (EAG)/g sampel dan total flavonoid sebesar 604.51 mg Ekuivalen Kuersetin (EK)/g sampel dan P2CK1B dengan ekstrak metanol dengan potensi antioksidan sedang dengan IC50 sebesar 113.98 μg/mL dengan total fenol sebesar 49.60 mg Ekuivalen Asam Galat (EAG)/g sampel dan total flavonoid sebesar 78.63 mg Ekuivalen Kuersetin (EK)/g sampel. Besarnya total fenol dan flavonoid berkorelasi dengan tingginya aktivitas antioksidan pada ekstrak.
Keyword: Antioksidan, Aquilaria crassna, fungi endofit, total fenol, total flavonoid

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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