Judul: Aktivitas Antibakteri Fraksi Kaya-Naringenindari Daun Gude(Cajanuscajan (L.) Millsp.) Terhadap Bakteri Salmonella Thypi
Abstrak: Gude (Cajanus cajan (L.) Millsp.) dikenal sebagai salah satu tanaman obat dan memiliki kandungan senyawa metabolit sekunder, serta berdasarkan kepercayaan masyarakat Kabupaten Bone, Sulawesi Selatan daunnya mampu mengobati penyakit tifus. Sampai saat ini belum ada upaya untuk mengidentifikasi senyawa aktif yang berpotensi menghambat bakteri Salmonella thyphi yang merupakan penyebab penyakit tifus. Oleh karena itu, penelitian ini bertujuan mengidentifikasi senyawa aktif dari daun gude tersebut dan menentukan kemampuan penghambatannya terhadap bakteri S.thypi. Serbuk daun gude diekstraksi dengan metode maserasi menggunakan pelarut metanol (20.30%). Selanjutnya ekstrak metanol diekstraksi cair-cair dan diperoleh fraksi n-heksana, etil asetat dan metanol. Fraksi etil asetat yang positif dalam menghambat bakteri S. thypi selanjutnya dielusi dengan kromatografi kolom gravitasi menggunakan eluen n-heksana dan etil asetat yang kepolarannya ditingkatkan secara bergradien dan diperoleh 70 subfraksi. Subfraksi 1 membentuk kristal kekuningan dan diperoleh 2 noda pada profil kromatografi lapis tipisKLT 1-dimensi dan 2-dimensi yang mengindikasikan kemurnian dari subfraksi tersebut. Identifikasi dengan kromatografi cair spektroskopi massa menunjukkan bahwa subfraksi 1 memiliki m/z 272 dengan fragmentasi stabil pada m/z 271. Senyawa yang memiliki m/z 272 sesuai dengan senyawa naringenin yang merupakan golongan flavanon dengan pola fragmentasi lanjut m/z 271, 177, 151, 119, 107, 93, dan 83. Fraksi kaya-naringenin diuji kemampuan penghambatannya terhadap bakteri S.thypi menggunakan metode Kirby-Bauer dan diperoleh diameter penghambatan 11 mm. Kontrol positif yang digunakan ialah kloramfenikol. Dapat disimpulkan bahwa fraksi kaya-naringenin memiliki kemampuan aktivitas antibakteri dan dapat digunakan untuk mengobati tifus.
Keyword: aktivitas antibakteri, Cajanus cajan, flavanon, Salmonella thypi, tifus

Judul: Isolasi Fraksi Aktif Ekstrak Daun Dandang Gendis (Clinacanthus nutans) Berpotensi sebagai Antibakteri
Abstrak: Ethanol extract of dan dang gendis leaves have been known to be toxic toward Artemia salina brine shrimp. This toxicity property was likely due to the existences of some of its secondary metabolites that have antibacterial properties. Hence, this plant could be used as a substitute of the synthetic drugs usage. The purpose of this study was to find the most active fraction of ethanol extracts of dandang gendis leaves as a potential antibacterial and to determine the group of the active compound. The ethanol extract was fractionated using flash chromatography with silica gel as the stationary phase and ethyl acetate: n-hexane (8:2) as the 1110bile phase resulted in total of four fractions (fraction I to 4). Then the capability of those fractions, to inhibit the growth of two types of bacteria, Escherichia coli and Staphylococcus aZlreliS was tested. Fractions I with concentration of 1000 ppm had the largest inhibitory zone with the area of 4.17 and 7 mm in diameter when it was tested on E. coli and S. aureus respectively. The formation of inhibitory zone showed that fraction I of the ethanol extract of danclang gendis to have a weak antibacterial effect toward E. coli and moderate effect (5-10 Illm) on S. aureus. Based on the phytochemical assay, fraction 1 showed positive result on steroid and flavonoid tests
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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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