Judul: Potensi Kitosan, Khamir, Aktinomiset dan Kombinasinya dalam Menghambat Busuk Antraknosa (Colletotrichum gloeosporioides (Penz.) Sacc.) Buah Jambu Kristal
Abstrak: Anthracnose due to C. gloeosporioides is one of important disease on crystal guava during storage. Biological control using chitosan, yeast, actinomycetes and their combination are a promising alternative to control postharvest diseases of fruits. The study has been designed to evaluate the potencial of chitosan, yeast, actinomycetes and their combination in suppressing crystal guava anthracnose. In vitro evaluated has been done by poisoning tests methods and in vivo evaluated has been done by coating a solution of chitosan, suspension of yeast, suspension of actinomycetes and their combination on the crystal guava. The result of in vitro test showed that suspension of YP, APS5, and their combination are more effective in suppressing C. gloeosporioides than experiments with using metabolit only. The result of in vivo test with inoculation pathogen showed that severity disease of YP+APS5sus, YPsus, CT, APS5sus, CT+APS5sus, and CT+YPsus are smaller or significantly different with control. The coating of solution CT, suspension of APS5 and CT+APS5 on crystal guava are most effective to maintained fruits rigidity and extending the shelf life of crystal guava.
Keyword: 

Judul: Penggunaan khamir antagonis untuk pengendalian penyakit antraknosa pada buah avokad selama penyimpanan
Abstrak: Anthracnose caused by Colletotrichum gloeosporioides is an important disease in avocado fruit during storage. An effective, cheap, and safe control method is necessary as an alternative to subtitute the use of fungicides in postharvest disease control. This research aims 1) to get a yeast antagonist from avocados that are effective in controlling anthracnose disease on avocado fruit, 2) to identify effective yeast antagonists to control anthracnose disease on avocado fruit, and 3) to examine mechanism of action of yeast antagonists in controlling anthracnose disease on avocado fruit. Research started with isolation of C. gloeosporioides and yeast from avocado fruit, followed by bioassay in vivo, antibiosis test, and chitinolitic activity test. In vivo testing was done by dipping avocado fruit on yeast cell suspension to suppress the anthracnose disease in avocado fruits. The isolation of yeasts from avocado obtained 23 yeasts isolates. Based on bioassay in vivo, there were eight yeast isolates (A28, A32, A33, A34, A35, A36, A37, A38) that effectively inhibited anthracnose disease in avocado fruit at a concentration of 106 cells/ml and 107 cells/ml. However, only four isolates were chosen for further characterization based on morphological and molecular identification. Two species of yeast was identified, i.e Pichia anomala (isolates A33 and A37) and Candida intermedia (isolates A35 and A36).
Keyword: 

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.
Keyword: