Judul: Molecular Phylogenetic Tree using Three Different Methods based on p-distance Model
Abstrak: Phylogenetic inference is needed in describing the relationship between proteins, genes or species. In phylogeny, the object is assumed to be evolutionary related. The evolutionary tree is used to show the evolutionary relationship among the organisms. However, to build reliable evolutionary tree, reliable set of data is needed to find the best model. In this paper, the data is obtained from D-loop region in mitochondrion DNA (mtDNA) that is available in Gen Bank. Five different species of animals were used, those were: Bison bison, Bos taurus, Bos indicus, Bubalus bubalis, and Capra hircus. The objective was to obtain the most reliable method, measured by its stability among UPGMA, Minimum Evolution, and Neighbor-Joining. To build the cases, five species were grouped into seven classes that have different characters. P-distance model was used to build the distance matrices. The reliability of each method was measured using the Felsentein’s bootstrap method. The whole bootstrap process for each method will be repeated 100, 1000, and 10000 times to detect its reliability. Almost all methods do not have the misclassified problems in reconstructing the evolutionary tree. However, Minimum Evolution failed to reconstruct a reliable evolutionary tree compared to UPGMA and Neighbor-Joining.
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Judul: Performance Comparison Between Kimura 2-Parameters and Jukes-Cantor Model in Constructing Phylogenetic Tree of Neighbour Joining (NJ)
Abstrak: Bioinformatics as a recent improvement of knowledge has made an interest for scientist to collect and analyze data to provide the best estimate of the true phylogeny. The objective of this research is to construct and compare the phylogenetic tree of Neighbour Joining (NJ) based on different models (Kimura 2-Parameters and Jukes-Cantor) and to find out which model is more reliable on constructing NJ’s tree. In order to build the tree, reliable set of data is conducted from D-loop mtDNA sequences that is available in Gen Bank. The nucleotide sequences come from Bison bison (American bison), Bos taurus (European cow such as Shorthorn), Bos indicus (zebu breeds), Bos grunniens mutus (one of subspecies of cow), and Capra hircus (species of goat). The reliability of each models was measured using the Felsentein’s bootstrap method. The whole bootstrap process for each models was repeated 1.000, 5.000, and 10.000 times to detect its reliability. The performance was measured on the basis of the consistency of the topology relationship, the stability of nodes, the consistency of bootstrap confidence level (PB), standard error of distance, change of PB from (1.000-5.000) to (5.000-1.000), computational time, and BIC score. NJ’s phylogenetic tree with kimura 2-parameters and jukes cantor model have a good node stability and is also generally successful in representing topological relationships between taxa. The increasing of bootstrap replication number in common will increase the consistency of bootstrap confidence value ( . It means both models have a good reliability. But, when the number of sequences is large and the extent of sequence divergence is low, it is generally difficult to construct the tree by any models. In conclusion, Kimura 2-Parameters has a better performance than Jukes-Cantor.
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Judul: Elektrodeposisi Film Tipis Semikonduktor Cu2ZnSnS4 (CZTS) pada Substrat Kaca ITO
Abstrak: Semiconductor Cu2ZnSnS4 (CZTS) thin film that can be used as absorber layers on solar cell module was made via electrodeposition method. CZTS thin film was electrodeposited on the surface of a silicate glass coated with a thin layer of indium tin oxide (ITO). Deposition process was done using potentiostatic mode at room temperature with a potential of 1.05 V for 30, 45, and 60 minutes, followed with annealing the film at 2 different temperatures, 500 ºC using furnace and 180 ºC using hot plate, both treatments for 45 minutes in N2/H2S atmosphere. The X-ray difractograms were analyzed using Match 2 program and showed that the CZTS thin films had kesterit crystalline structure, with a low percentage of CZTS phase. The thin film also contained secondary phases such as Cu2S, ZnS, and SnS. The obtained CZTS thin films had a thickness between 1.039 and 1.676 μm. Absorption study showed that the band gap energy of CZTS thin films which was annealed using furnace ranged from 1.50 to 1.52 eV, whereas that annealed using the hot plate was not observed. The band gap energy value showed that CZTS thin films can be used as sunlight absorber layers on solar cell. The formation of CZTS crystal film on this investigation was effectively performed using furnace annealing process at a temperature of 500 ºC with deposition time of 45 minutes.
Keyword: Thin film, Electrodeposition, Cu2ZnSnS4