Judul: Pengaruh efek residu terhadap karakter fisik dan kimiawi serta aktivitas antioksidan kulit buah Manggis (Garcinia mangostana L.)
Abstrak: Komoditas manggis memiliki nilai ekonomi yang tinggi dan sangat potensial untuk dikembangkan menjadi komoditas ekspor unggulan. Potensi manggis tidak hanya terbatas pada buahnya saja, tetapi hampir seluruh bagian tumbuhan manggis menyimpan potensi yang sangat bermanfaat bagi kehidupan manusia. Species Garcinia diketahui kaya akan kandungan senyawa polifenol yang memiliki aktivitas antioksidan tinggi. Adanya pengaruh suatu faktor budidaya terhadap peningkatan sejumlah senyawa kimia tertentu yang terdapat pada buah manggis dan bermanfaat bagi kesehatan, merupakan suatu peluang untuk meningkatkan nilai tambah buah manggis. Penelitian ini bertujuan untuk mengetahui pengaruh hara N, P, dan K terhadap karakter fisik dan kimia buah manggis dan mengetahui pengaruh hara terhadap aktivitas antioksidan kulit manggis. Penelitian dilakukan di Laboratorium Pasca Panen dan Laboratorium Analisis Tanaman dan Kromatografi, Departemen Agronomi dan Hortikultura, Institut Pertanian Bogor. Penelitian dilaksanakan dari bulan Februari – Juli 2010. Penelitian ini merupakan penelitian lanjutan, tanaman manggis yang digunakan merupakan tanaman yang sebelumnya pernah digunakan untuk penelitian pemupukan selama 5 tahun sejak tahun 2004 hingga 2008 dan tanaman tersebut sudah pernah berbuah beberapa kali.
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Judul: Karakter Kulit Manggis, Kadar Polifenol Dan Potensi Antioksidan Kulit Manggis (Garcinia mangostana L.) Pada Berbagai Umur Buah Dan Setelah Buah Dipanen
Abstrak: The objective of this study were to know the character of mangosteen rind during development of the mangosteen fruit, studying the total phenol content and antioxidant potential of mangosteen rind. Research was done at Plant Analysis and Chromatoghrapy Laboratory, Deparment of Agronomy and Horticulture, Bogor Agricultural University. This research used Completely Randomized Desain Group (RKLT) single factor wich is harvesting, with continue test Duncan Multiple Range Test (DMRT) at level 5%. Harvesting one month after anthesis (BSA), 2 BSA, 3 BSA, 4 BSA and the rind storage two and four weeks after harvesting were done separately. Mangosteen fruit was harvested from Leuwiliang, Bogor. The result showed that total phenolic at crude extract mangosteen and antioxidant capacity to reach IC50 of harvesting and storage have negative correlation. Harvesting handling have effect to fruit weight, aril weight, wet weight rind and vitamin C content. Total phenolic of Harvesting and storage handling have a negative correlation with antioxidant capacity to reach IC50 which are value about -0.53 and -0.91. Assumed that total phenolic content will increase antioxidant capacity in mangosteen rind. Antioxidants capacity on harvesting and sorage handling of mangosteen have IC50<50 (capability of antioxidant are very strong).
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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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