Judul: Keanekaragaman Selaginella di Jawa Tengah
Abstrak: Selaginella is a single genus belong to family Selaginelaceae which include approximately 750 species spread all over the world. The diversity of Selaginella can be found in lowland to mountain rainforest. This study aimed to describe the diversity of morphological characters and the distribution of Selaginella in Central Java, then to provide descriptions and identification key of Selaginella species in Central Java. The method used to assess the diversity Selaginella in Central Java included observation and identification of morphological characters. In Central Java, there were found 10 species of Selaginella, namely S. plana, S. remotifolia, S. involvens, S. ornata, S. ciliaris, S. opaca, S. modica, S. aristata, S. subalpina, and Selaginella sp. Selaginella varied on some morphological characteristics such as branching pattern, rhizofor, lateral leaves, median leaves, axillary leaves, and Strobilus shape. The distribution of Selaginella is fairly even in Central Java ranging from the altitude of 200 to 2771 m asl. Selaginella species found in the lowest altitude was Selaginella sp. (200 m asl), while at the highest altitude was S. plana (2771 m asl).
Keyword: Selaginella, Selaginellaceae, Taxonomy, Central Java.

Judul: Biodiversity, Ethnobotany, and Antioxidant Ability of Selaginella spp. from Halimun-Salak Mountain National Park (TNGHS).
Abstrak: Biodiversity and ethnobotany of Selaginella were studied in Halimun-Salak Mountain National Park (TNGHS) to describe the diversity and the use of Selaginella as medicinal plant. The diversity study of Selaginella was done by exploring Selaginella at 6 sampling points. The ethnobotany study of Selaginella was done by interviewing respondents at the villagers around Bunder Mountain, Citalahab Sentral, and Kasepuhan Adat Banten Kidul. There were eight species Selaginella found in TNGHS which were S. willdenovii, S. ornata, S. plana, S. intermedia, S. involvens, S. alutacia, S. subalpina and one species that has not been identified yet. The first two species were found dominantly in this location. The community in the location of study called Selaginella as paku rane. At the villages around Bunder mountain and Citalahab Sentral, Selaginella is also called as rande. The plant was traditionally used as fresh vegetables, postnatal and wound treatment, and body fitness maintenance. Antioxidant ability of Selaginella was tested by performing hydroxyl radical scavenging activity based on Fenton reaction. Three species of Selaginella were tested their hydroxyl radical scavenging activity. S. plana was the most potential species as an antioxidant followed by S. ornata and S. willdenovii. The crude extract of S. plana showed the best antioxidant activity at concentration of 75 μg/ml. Key words: Selaginella, biodiversity, ethnobotany, antioxidant, Halimun-Salak Mountain National Park (TNGHS)
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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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