Judul: Kendali Mutu Rimpang Temulawak (Curcuma xanthorrhiza) menggunakan Fotometer Jinjing dengan Analisis Kemometrik
Abstrak: Temulawak (Curcuma xanthorrhiza) is widely used herb in Indonesia. The complex composition of the herbal extract requires quality control in the evaluation. This study aimed to develop portable photometer as a quality control device for temulawak rhizome age 9 months based on quality diversity of stem rhizome and branch rhizome that was combined with pattern recognition techniques (PCA & PLSDA) and compare the result of the analysis with high performance liquid chromatography (HPLC) method. PCA analysis on portable photometer data with 8 filters was able to classify stem rhizome and branch rhizome with just 2 main components. Curcuminoid content of stem rhizome was higher than the branch rhizome in plant 2, 4, and 8, and its grouping was in accordance with PCA analysis result using 3 filters (blue-green, green-yellow, and yellow) only on stem fresh rhizome samples. The grouping formed a PLSDA model with plant 2, 4, and 8 were in group A and the curcuminoid content fell into that respective range. It indicates that portable photometer as an alternative instrument cannot provide quantitative results based on differences of stem and branch rhizomes, but fairly informative in grouping stem rhizome and branch rhizome.
Keyword: temulawak, quality control, portable photometer, curcuminoid, chemometric

Judul: Development of Portable Photometer for Quality Qontrol of Temulawak Rhizome (Curcuma xanthorriza).
Abstrak: Temulawak (Curcuma xanthorriza) is one of medicinal plants grown and used as a medicine in Indonesia. A good medicine requires temulawak with good quality, which is determined by its chemical composition. The diversity of chemical components of temulawak can be determined using spectroscopic methods. The purpose of this research is to develop portable photometer as instrument for quality control of temulawak rhizome by evaluating the quality based on the different harvesting age and combined with pattern recognition using principle component analysis (PCA) and partial least square discriminant analysis (PLSDA). Temulawak rhizomes with different plant ages (6, 7, 8, and 9 months) were measured using a portable photometer, and then combined using PCA and PLSDA techniques. The results showed that temulawak rhizomes from different ages were readily distinguished. PCA analysis using two main components: PC 1 = 66% and PC 2 = 21%. For the analysis of values obtained PLSDA R2 close to 1 and root mean square error of prediction (RMSEP) close to 0, and also it produced 4 models (6, 7, 8, and 9 months). Quality of the rhizomes samples 7, 8, 9 month declined at prolonged storage. This was due to decreased levels of active chemical compounds contained in the rhizome samples.
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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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