Judul: Pengoptimuman metode ekstraksi dan isolasi xantorizol dari temu lawak (Curcuma xanthorrhiza Roxb.)
Abstrak: Xantorizol merupakan senyawa penciri pada temu lawak yang memiliki aktivitas antibakteri dan antijamur. Penelitian ini telah mengembangkan metode ekstraksi dan isolasi senyawa xantorizol dari temu lawak (Curcuma xanthorrhiza Roxb.). Teknik maserasi dan sokletasi dilakukan untuk mengekstraksi xantorizol dengan metanol, dietil eter, dan n-heksana sebagai pelarut. Pemurnian selanjutnya menggunakan kromatografi kolom dan kromatografi lapis tipis preparatif. Xantorizol hasil isolasi dicirikan berdasarkan spektrum ultraviolet-tampak dan inframerah juga kromatogram gas-spektrum massa serta ditentukan kemurniannya dengan kromatografi cair kinerja tinggi. Ekstrak n-heksana hasil maserasi (168 mg/g) memiliki kandungan xantorizol lebih tinggi dibanding ekstrak lainnya. Fraksi ke-4 hasil fraksionasi ekstrak n-heksana dengan kromatografi kolom memiliki rendemen akhir dugaan xantorizol sebanyak 0.016 % dengan tingkat kemurnian 87.4 %.
Keyword: Bogor Agricultural University, Institut Pertanian Bogor, IPB, Isolasi, Karakterisasi senyawa, Temu lawak, Xantorizol

Judul: Isolasi dan Pemurnian Xantorizol dari Temu Lawak (Curcuma xanthorrhiza Roxb.)
Abstrak: Xanthorrhizol is the main active component in the essential oil of temu lawak (Curcuma xanthorriza Roxb.). Xanthorrhizol has antifungal, antibacterial, antioxidant, and anti-inflammatory activities. Xanthorrhizol is isolated by Asriani (2010) using solvent extraction (ethanol 96%), acetylation, Preparative Thin Layer Chromatography (PTLC), and deacetylation, which produce xanthorrhizol with 99% purity. The xanthorrhizol obtained is not pure because there are still other compounds in the mixture. This research perfoms xanthorrhizol isolation using three different modifications based on Asriani’s method. The modified method I conducts two-times extraction: ethanol and hexane extractions. The modified method II conducts three-times extraction: ethanol, hexane, and diethyl ether extractions. The modified method III conducts two-times extraction using ethanol and hexane as solvents, and also conduct PTLC phase II in order to extract the deacetylated product. The modification method I and II produce xanthorrhizol with purity 78.1 and 80.1 % for ethanol extract, and 80.1 and 88.1 % for hexane extract, respectively. Modified method III is able to isolate xanthorrhizol with the highest purity, i.e. 94.3%. GC-MS analysis to the product shows that one of the two peaks appeared at the retention time of 11.44 minutes with an area of 94.3% and MW 218.0 is xanthorrhizol. The results from all of these modified methods were lower than Asriani’s method, which comes to the conclusion that Asriani’s method is better and more efficient.
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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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