Judul: The Effect of Melaleuca and Tumeric Essential Oils in Impending the Growth of Rhizoctonia sp. in Vitro
Abstrak: Tanaman yang terserang penyakit dapat merugikan berbagai aspek, salah satunya dapat menurunkan kualitas tanaman. Penggunaan pestisida nabati merupakan salah satu solusi untuk mencegah serangan penyakit. Penelitian ini bertujuan mengetahui daya hambat dan konsentrasi minyak atsiri yang bekerja optimal. Pengamatan dilakukan dengan menggunakan minyak atsiri kayu putih, minyak atsiri kunyit, dan kombinasi keduanya dengan konsentrasi 1%, 3%, dan 5% pada media PDA dan media PDB. Hasil penelitian ini dianalisis dengan rancangan acak lengkap faktorial dan uji lanjutan apabila berpengaruh nyata. Hasil pengamatan menunjukkan minyak atsiri yang optimal sebagai penghambat pertumbuhan patogen adalah minyak atsiri kunyit konsentrasi 3% dan minyak atsiri kombinasi konsentrasi 5%.
Keyword: Deuteromycota, eucalyptus, factorial complete randomized design, turmeric, vegetable pesticides

Judul: The Influence of Patchouli (Pogostemon cablin Benth.) and Turmeric (Curcuma domestica Val.) Essential Oils on The Growth of Rhizoctonia sp. in Vitro
Abstrak: Minyak atsiri merupakan salah satu komponen yang dapat dijadikan sebagai pestisida nabati karena memiliki kandungan yang bersifat antifungi seperti kandungan senyawa pada minyak atsiri nilam dan kunyit. Penelitian ini bertujuan menguji daya hambat minyak atsiri nilam dan kunyit beserta kombinasinya dengan berbagai konsentrasi terhadap pertumbuhan Rhizoctonia sp. secara in vitro. Pengamatan dilakukan dengan menggunakan minyak atsiri nilam, kunyit, serta kombinasi nilam dan kunyit dengan konsentrasi 1%, 5%, dan 10% pada media Potato Dextrose Agar (PDA) dan Potato Dextrose Broth (PDB). Hasil uji penghambatan patogen secara in vitro menunjukkan bahwa jenis dan konsentrasi minyak pada media PDA berpengaruh nyata terhadap penghambatan Rhizoctonia sp., sedangkan pada media PDB hanya konsentrasi yang berpengaruh nyata. Kombinasi minyak atsiri dengan konsentrasi 10% pada media PDA dan kunyit dengan konsentrasi 10% pada media PDB menunjukkan respon penghambatan tertinggi., Essential oil is a component that can be used as a biopesticide because it contains antifungal properties, such as the compounds in patchouli and turmeric essential oils. This study examines the inhibition of patchouli and turmeric essential oils and their combinations with various concentrations on the growth of the pathogenic fungus Rhizoctonia sp. in vitro. Observations were made using patchouli essential oil, turmeric, and an assortment of patchouli and turmeric with concentrations of 1%, 5%, and 10% on Potato Dextrose Agar (PDA) dan Potato Dextrose Broth (PDB) media. The in vitro pathogen inhibition test showed that the inhibitory effect of Rhizoctonia sp. by type and concentration of essential oil on PDA media was significant. In contrast, on PDB media, only attention had a significant impact. The combination of essential oils with a concentration of 10% on PDA media and turmeric with a concentration of 10% on PDB media showed the highest inhibitory response.
Keyword: Antifungal, damping-off, metabolit sekunder/secondary metabolites, pestisida nabati/biopesticides

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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