Judul: Evaluasi Kadar Kurkuminoid Rimpang Temulawak (Curcuma xanthoriza Roxb.) Menggunakan Analisis Citra Berbasis Red Green Blue
Abstrak: Turmeric (Curcuma xanthoriza Roxb.) is one of the important natural product in Indonesia. Quality of turmeric is dictated by content of curcuminoid. The curcuminoid content could be determined by spectrophotometry, titration volumetry, or chromatography, but those analytical methods are destructive to the material and need long time. One of rapid and nondestrucive method is image analysis. The objectives of this research were to evaluate content of curcuminoid using image analysis based on red green blue (RGB). Picture taking for image analysis was using USB Digital Microscope with enlargement 800x and curcuminoids were measured using spectrophotometry Uv-Vis at wavelength of 420 nm. The data showed that RGB value is equivalent with the content of curcuminoid. The result can be used as parameter to differentiate turmeric with harvest age 3, 6, and 9 months. The obtained equation of predicted content of curcuminoid is y = - 0,22 - 0,0062 R + 0,0643 G - 0,0330 B, R² = 96,1%.
Keyword: turmeric., RGB, curcuminoid, image analysis

Judul: Penentuan Kadar Kurkuminoid dalam Kunyit dengan Spektrofotometri Derivatif
Abstrak: Indonesia as one of agricultural countries has various kinds of plant than can be used for pharmaceutical product, including turmeric that contains curcuminoid compound. Curcuminoid has efficacy as an antihepatoxic, anticholesterol, tumor and cancer inhibiting compound. In recent years, research has been developing a simple, fast, and low-cost analysis method from spectroscopy and chemometric combination, i.e. ; derivative spectrophotometry. In this research, turmeric extraction was conducted using sonication method, and its curcuminoid content was determined using spectrophotometry method. Analysis with UV-vis spectrophotometry and high performance liquid chromatography (HPLC) were also conducted as reference methods. Curcuminoid in turmeric using derivative spectrophotometry was 14.33 mg/g whereas with UV-vis spectrophotometry and HPLC were 14.18 and 45.40 mg/g, respectively. Based on statistical analysis for these results, derivative spectrophotometry can be applied for analyzing curcuminoid content with good accuracy and precision. This developed method was cheaper, faster, and easier than the conventional method. In addition, matrices influence in samples can be reduced compared with that using conventional spectrophotometry.
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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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