Judul: Kajian Aktivitas Antioksidan dan Antimikroba Ekstrak  Biji, Kulit Buah , Batang dan Daun Tanaman Jarak Pagar  (Jatropha curcas L.)
Abstrak: Saat ini, jarak pagar (Jatropha curcas L.) menjadi salah satu tanaman penghasil bahan bakar nabati yang cukup pesat perkembangannya. Selain pemanfaatan sebagai bioenergi, jarak pagar juga berpotensi dalam pengembangan produk di bidang pertanian, obat-obatan serta produk perlindungan tubuh. Tanaman jarak mengandung senyawa-senyawa aktif seperti β-sitosterol, stigmasterol, curcin, flavonoid dan 12-deoksil-16-hidroksiforbol (forbol ester). Ekstrak pelarut forbol ester memiliki kemampuan membunuh serangga, fungi, dan moluska sehingga berpotensi sebagai antimikroba. Curcin bersifat antimikroba yang dapat melawan Staphylococcus aureus dan Escherichia coli (Tim Jarak Pagar RNI, 2006). Menurut Hodek et al. (2002), flavonoid yang tekandung dalam ekstrak kulit batang jarak memiliki aktivitas biologi seperti antimikroba, anti alergi dan antioksidan. Kandungan senyawa-senyawa aktif pada tanaman jarak perlu diketahui dengan benar sehingga dapat menjadi dasar pengembangan produk-produk turunan senyawa aktif berbasis jarak pagar. Tujuan dari penelitian ini adalah untuk mengetahui rendemen ekstrak yang terkandung pada berbagai bagian tanaman jarak pagar yang terdiri dari biji, kulit buah, batang dan daun jarak pagar serta untuk mengetahui aktivitas antioksidan dan aktivitas antimikroba dari bagian - bagian tanaman tersebut.
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Judul: Aktivitas Antioksidan dan Antimikroba Fraksi Ekstrak Daun dan Ranting Jarak Pagar ( Jatropha curcas L. ) serta Pemanfaatannya pada Produk Personal Hygien
Abstrak: The development of jarak pagar (Jatropha curcas L) in Indonesia need to be followed by the optimum utilization of all parts of the plants, including the leaves and twigs. Assessment of antioxidant and antimicrobial activity of leaves and twigs extract/extract fraction of Jatropha curcas L and their use in personal hygiene products, is an effort to increase added value of Jatropha curcas’s leaves. Extract of Jatropha curcas in this study were obtained trough a solvent extraction process using ethanol 96% by the method of soxhlet and maceration. Extract fraction obtained by performing advanced stages in the extract called fractination. Antioxidant activity was analized by using DPPH method at concentration of 4, 6, 8, 10, 12, and 20 ppm. While the analysis of antimicrobial activity performes by well diffusion method against Candida albicans, Microsporum gypseum, and Pseudomonas aeruginosa at the concentration of extract/extract fraction 1, 2, and 3%. The result showed that crude extract of maceration and ethyl acetate fraction of soxhlet have the highest antioxidant activity with IC50 values of 7.2 and 7.8 ppm where this values were not significantly different. In other side, the result of antimicrobial activity indicated the present of antimicrobial inhibitory of maceration crude extract against Microsporum gypseum. It proved by the formation of clear zones of inhibition around the wells with diameter of 12, 14, and 20 mm for concentration 1, 2, and 3%. The ethyl acetate fraction showed the inhibitory against Microsporum gypseum only at concentration of 3% extract with diameter of inhibitory zones 14 mm. The extract/extract fraction showed no inhibitory activity against other microbes. Utilization of selected extract fraction applied to one of personal hygiene product, transparent soap, by utilizing its antioxidant activity. Soap with the addition of ethyl acetate fraction of Jatropha curcas at a concentration level of 1.0% produces soap with antioxidant activity of 37.25% and the rate of foam stability about 83.23%.
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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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