Judul: Tingkat Retensi Karoten Total dan Protein serta Aktivitas Antioksidan Masakan Torbangun (Coleus amboinicus Lour)
Abstrak: Bataknese Simalungun women in North Sumatra who consume Torbangun soup believe that it can stimulate the breast milk production. Until now information and use of Torbangun is still very limit. People need to know more about Torbangun apart from its benefit but also on the effect of cooking towards nutrients especially those sensitive to the total carotenoids and proteins as well as antioxidant activity. The purpose of this research was to study the effects of Cuisine types on the retention of carotenoids, protein, and antioxidant activity of Torbangun cuisine. There are three types of Torbangun cuisine used in this study namely lodeh, pecel, and stir-fry. Chemical analysis conducted in this study include the analysis of water, fat, protein, ash, carbohydrate cntents, total carotene, and antioxidant activity. The study used Complete Randomized Design (CRD). Data were analyzed using Analysis of Variance, Duncan, and independent T-Test. Cuisine types significantly effected the nutrient content of water, ash, carbohydrates, and carotene, while there were no significant effect of the nutrient content of fat, and protein then antioxidant activity. The contribution of vitamin A in the torbangun cuisine (per serving) was more than 20% of the recommended reference Label Nutrition (ALG), so that these products can be categorized as high provitamin A. Independent T-Test results showed that the levels of crude carotene lodeh before and after cooking were significantly different (p <0.05), whereas carotene levels of pecel and stir-fry were not significantly different, as well as protein content and antioxidant activity before and after cooking (p > 0.05).
Keyword: 

Judul: Pengaruh Proses Pelleting Terhadap Kelarutan dan Aktivitas Anti Bakteri Daun Torbangun (Coleus amboinicus Lour)
Abstrak: Torbangun (Coleus amboinicus Lour) is a herb that can be used as feed supplement. Processing torbangun into pellets is one of the way to keep the nutritional content to not easily damaged, improve efficiency and can be saved. The purpose of this research was to study the effect of processing plants into pellets with different water content on the solubility and antibacterial activity of torbangun (Coleus amboinicus Lour). The experimental design of this study used a Completely Randomized Design (CRD) of 3 treatments, which were P1 (12%), P2 (13.5%), and P3 (15%) with 3 replications. The variables measured were solubility and anti-bacterial Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Salmonella typhimurium. The results showed that the pelleting process lowered the value of the solubility and antibacterial activity in torbangun. Different levels of water content had no effect on the solubility, while the antibacterial activity showed different result depending on the type of bacteria because each bacteria react differently.
Keyword: torbangun., test the inhibition of bacterial, solubility test

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.
Keyword: