Judul: Analisis Fitokimia Dan Aktivitas Antioksidan Ekstrak Daun Sengon (Paraserianthes falcataria (L) Nielsen) Menggunakan Metode DPPH
Abstrak: Kedawung (Mimosaceae family) has been shown to have high antioxidant content. Therefore, sengon leaf that belong to the Mimosaceae family is alleged to have potential as a source of natural antioxidants. Utilization of sengon leaf as food supplements with antioxidant activity has not been done. Therefore, this study aims to examine and to analyze the antioxidant activity of bioactive components. The antioxidant activity was determined by DPPH method and measured with a spectrophotometer at a wavelength of 517 nm. The results showed that the antioxidant activity is highest in the 96% ethanol extract of leaves sengon expressed as IC50, specifically 2.76 ppm. The antioxidant activity was caused by the content of secondary metabolites in the sengon leaf, such as alkaloids, saponins, flavonoids, tannins and phenolics, steroids and triterpenoids. The analysis showed that the antioxidant activity, total phenolic content (275.74 GAE mg/g) and total flavonoid (83.60 CE mg/g) sengon leaf are quite good and can be used as benchmark for natural antioxidant source.
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Judul: Aktivitas Inhibisi Enzim α-Glukosidase dan Toksisitas Ekstrak Air dan Ekstrak Etanol Daun Sengon (Paraserianthes falcataria (L) Nielsen)
Abstrak: Paraserianthes falcataria (L) Nielsen has been shown to have a high bioactivity. Utilization of sengon leaf as a antidiabetic has not been done. This study aims to examine the antidiabetic activity and toxicity of water and ethanol extracts of the sengon leaves. Antidiabetic activity of the extracts was tested by the method of inhibition against α-glucosidase enzyme. Cytotoxicity of Paraserianthes falcataria (L) Nielsen. extracts was conducted by BSLT. Extraction of Paraserianthes falcataria (L) Nielsen. Inhibition of α-glucosidase enzyme extract water, ethanol 70%, and 96% had IC50 values, respectively for 1541.667 and 1213.090 ppm, the IC50 of water extract could not be calculatet because its inhibition activity is less than 50%. IC50 values for acarbose as a comparison is 0.311 ppm. The test results in 70% and 96% ethanol extract showed Paraserianthes falcataria (L) Nielsen. not have an antidiabetic. Toxicity testing of water extract, ethanol 70%, and 96% gain in a row LC50 value of of 499 677 , 373 342 and 383 270 ppm. Means that all the tested extracts are toxic.
Keyword: Bogor Agricultural University (IPB), Totoxicity, Inhibition, α-Glucosidase, Sengon

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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