Judul: Evaluasi Perubahan Metabolit pada Temulawak dengan Waktu Tanam Berbeda
Abstrak: Curcuma is an indigenous plant of Indonesia which processes biological activity as an antioxidants. Metabolites which play a role in the antioxidant activity of curcuma are curcuminoids the concentration of which are influenced by planting time. FTIR spectroscopy is a qualitative method of used to distinguish the changes in metabolites of curcuma at different planting time. The aims of this research is to correlate levels of curcuminoids and xanthorrizol with the antioxidants capacity and to evaluate and distinguish metabolite changes in rhizomes of curcuma at different planting time using FTIR. The antioxidant activity determined by three methods which is DPPH, FRAP and CUPRAC. The content of curcuminoids and xanthorrizol determined by HPLC method. The results showed that the age of nine months of curcuma has the highest concentration of curcuminoids and xanthorrizol. Based on correlation analysis it was found that the antioxidant capacity of DPPH method has a positive correlation (0.757 r 0.996) with curcuminoids or xanthorrizol, like that on the method of FRAP (0.522 r 0.976). In CUPRAC method a high correlations indicated by total yield (r = 0.986). FTIR spectral analysis gave absorption for functional group of OH (3389-3371 cm-1), carbonyl group (1628 cm-1), vibration stretching C-H by 2855-2962 cm-1 and 1053 cm-1. FTIR spectroscopy can be used to analyze changes in metabolites in different planting time.
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Judul: Variation of Antioxidant Activity and Total Flavonoid Content of The Rhizome  of Curcuma xanthorrhiza Roxb. with Three Different Cultivation Locations
Abstrak: Temulawak (Curcuma xanthorrhiza Roxb.) dapat menghasilkan metabolit sekunder dan memiliki peran sebagai sumber antioksidan. Temulawak dapat menghasilkan variasi akumulasi metabolit sekunder jika ditanam pada lokasi dengan kondisi lingkungan yang berbeda-beda. Penelitian ini bertujuan memperoleh pola interaksi genotipe temulawak dengan lingkungan penanaman multilokasi (Bogor, Cianjur, dan Sukabumi) serta memperoleh hasil evaluasi stabilitas dari setiap genotipe. Kadar total flavonoid temulawak tertinggi diperoleh dari penanaman di Sukabumi dengan nilai 21,3791 mg QE/g bobot kering. Genotipe dengan kadar total flavonoid tertinggi adalah G6 dengan nilai 23,2428 mg QE/g bobot kering. Aktivitas antioksidan tertinggi berdasarkan lokasi diperoleh dari penanaman di Sukabumi dengan nilai 9,6371 μmol TE/g bobot kering dan berdasarkan genotipe yakni G3 dengan nilai 9,1943 μmol TE/g bobot kering. Keragaman ulangan berpengaruh nyata pada parameter kadar total flavonoid dan tidak ditemukan interaksi genotipe dan lingkungan pada kedua parameter. Genotipe yang stabil pada ketiga lokasi (Bogor, Cianjur, Sukabumi) adalah G5 untuk kadar total flavonoid dan G3 dan G4 untuk aktivitas antioksidan. Genotipe G5 memiliki potensi stabil pada lokasi penanaman di Bogor dengan parameter aktivitas antioksidan.
Keyword: antioxidant, flavonoids, multilocation, temulawak

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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