Judul: Peran Propolis Trigona spp. Asal Pandeglang Terhadap Tiga Bakteri Asam Laktat
Abstrak: Propolis is known to have an antimicrobial activity and can prevent various diseases. Propolis consumption is feared to have negative impact on the activity of digestive lactid acid bacteria (LAB). The aim of this research was to examine the effect of propolis on the growth and lactid acid production of three LAB. Propolis concentrations examined were 0% (control), 0,2%, 0,6%, 1% and commercial propolis at 0,4% concentration. The parameters analyzed were the growth of bacteria counted with Total Plate Count (TPC) method and lactid acid production using titrable acidity analysis. Propolis at 0,6% concentration stimulated the growth of Lactobacillus casei subsp. rhamnosus (23,725x108 cell/mL), but inhibitted the average lactid acid production (0,071%) lower than control (0,149%). Propolis did not affected the growth of Streptococcus thermophillus, but propolis at 0,6% concentration stimulated the average lactid acid production (0,182%) higher than control (0,112%). Propolis inhibitted the growth of Lactobacillus delbrueckii subsp. bulgaricus, but at 0,2% concentration, its population was still highest (3,775x108 cell/mL) and the average lactid acid production was stimulated (0,195%) higher than control (0,123%).
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Judul: Antibacterial Activity of Trigona spp. Bee Propolis From Pandeglang Against Enterobacter sakazakii.
Abstrak: Propolis has many advantages and specific potencies, due to its properties as antibacterial, antivirus, and anticancer. The characteristics and properties of E. sakazakii has been studied well due to its physiological properties and resistances in the environment. The research aim is to determine the propolis potency of Trigona spp as antibacterial agent against E. sakazakii. Propolis was extracted from bee hives of Trigona spp using maceration method with ethanol 70% (propolis extract) yielded 17,76% extract. The antibacterial activity test was performed by a modified agar well diffusion against three isolates of bacteria E. sakazakii IB-19b, IB-29a, and ATCC 35217. Through the initiation test, propolis activity was higher than commercial propolis, and lower than ampicillin. The effectivities of propolis extract to commercial propolis for each isolate IB-19b, IB-29a, and ATCC 35217 were 143,99%, 169,65%, and 155,76% respectively. The effectivities of propolis extract to ampicillin for each isolate IB-19b, IB-29a, and ATCC 35217 were 39,37%, 38,94%, and 47,37% respectively. The minimum inhibition concentration differed for each isolate, the minimum inhibition concentration for IB-19b, IB-29a, and ATCC 35217 were 12,50%, 25,00%, and 50,00% respectively. The propolis activity to each isolate showed the concentration dependent activity, the antibacterial activity decrease as the propolis concentration decrease.
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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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