Judul: Efek Zat Antibakteri Daun Torbangun (Coleus amboinicus Lour) terhadap Bakteri yang Berasal dari Makanan Basi
Abstrak: Penggunaan komponen tumbuhan sebagai tujuan farmaseutikal meningkat dalam beberapa studi terakhir. Produk-produk tumbuhan mempunyai sifat antibakteri karena adanya komponen aktif yang dapat disintesis didalamnya. Daun Torbangun diyakini memiliki khasiat sebagai penawar racun (antibakteri) dan obat untuk menyembuhkan penyakit seperti sariawan dan batuk. Penelitian ini bertujuan untuk mengetahui efek zat antibakteri daun Torbangun terhadap bakteri yang berasal dari makanan basi serta mengetahui efek dari zat antibakteri daun Torbangun sebagai bahan obat herbal. Penelitian memiliki beberapa tahapan yaitu Pemilihan sampel pada 30 orang mahasiswa IPB, Isolasi dan identifikasi bakteri, Uji Perlakuan daun Torbangun, dan Uji aktivitas antibakteri. Terdapat perbedaan nyata (p<0.05) aktivitas zat antibakteri perlakuan ekstrak terhadap perlakuan lainnya (daun yang dikeringkan, direbus, dan ditumbuk). Setelah dilakukan uji regresi linear, tidak terdapat perbedaan nyata antara jenis perlakuan terhadap luas hambatan diameter zona hambat terhadap bakteri gram positif maupun gram negatif (p>0.05).
Keyword: aktivitas antibakteri, bakteri, daun Torbangun (Coleus amboinicus Lour), perlakuan

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.
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