Judul: Aplikasi dan Karakterisasi Sifat Fisik-Mekanik Plastik Biodegradable dari Campuran LLDPE dan Tapioka
Abstrak: Plastik mempunyai peranan penting dalam kehidupan manusia. mulai dari sekedar pemenuhan kebutuhan yang sangat sederhana sampai pada kebutuhan yang serba rumit dan canggih. Akan tetapi, sampah plastik menjadi masalah lingkungan berskala global karena plastik tidak dapat terombak dalam lingkungan. Pengembangan bahan plastik biodegradable merupakan salah satu alternatif untuk memecahkan masalah ini.
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Judul: Produksi Plastik Komposit dari Campuran Tapioka-Onggok Termoplastis dengan Compatibilized Polietilen
Abstrak: One of alternative solution for plastic disposal problem is by developing biodegradable plastic. The typical drawbacks of starch-based plastic is inferior of its physico-mechanical properties. In order to improve the physico-mechanical properties and compatibility of blending system, tapioca-casava bagasse was modified into thermoplastic tapioca-casava bagasse blends while polyethylene was compatibilized by addition maleic anhydride. The aim of this research was to produce composite plastic from thermoplastic tapioca-casava bagasse blends and compatibilized polyethylene (compt-HDPE, compt-LDPE and compt-LLDPE). This research investigated the effect of fiber content in formulating the tapioca-casava bagasse blends, as 5, 10, 15 and 20%; glycerol (as plasticizer) concentration, as 30, 35 and 40% to the mechanical, thermal, biodegradability and surface morphological properties of composite plastics. The result showed that fiber contents in blends tapioca-casava bagasse up to 15% can improve physico-mechanical properties (tensile stress at yield, tensile stress at break and thermal properties) but addition of glycerol more than 30% can decrease mechanical composite plastic properties especially for HDPE. Introduction of thermoplastic tapioca-casava bagasse in polyethylene composite plastic generally can decrease physico-mechanical properties plastic. Synthetic polymer that suitable with thermoplastic blends tapioca-casava bagasse was compt-HDPE. The best result gained from 40% thermoplastic blends with HDPE, 15% of fiber and 30% of glycerol contents. Biodegradability test showed that composite plastic can be degraded, but only natural component such as starch and fiber was degraded.
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Judul: Mitochondrial DNA Gene Organization and Phylogenetic Relationship of Naja siamensis
Abstrak: Naja siamensis is one of Asiatic cobra in the Family of Elapidae, known as a cryptic snake. It has many morphological variations that lead to misidentification. Misidentification can cause the wrong concept in developing antivenom types due to high snakebite cases occur in Thailand. Thus, an accurate species identification using a molecular approach is crucially required. Mitochondrial DNA has been used widely in snake molecular studies. These studies were aimed to determine the arrangement of the N. siamensis partial mitochondrial genes using reptile-oriented primers and to reveal the phylogenetic relationship among other species of Asian cobra. DNA extraction was carried out based on the standard DNA salting-out protocol and was conducted by bioinformatics analysis using BLASTn and MEGA 6 software. Gene annotation was performed against N. kaouthia complete genome. A total of 3121 bp of N. siamensis mtDNA genes were sequenced consisting of partial of six regions: 16S rRNA, ND1, tRNA-Ile, CRII region, tRNA-Leu, tRNA-Gln, and COI genes. The mtDNA gene organization of N. siamensis was predicted to has a similar pattern with the common Elapidae mtDNA gene organization. This study showed that there is a monophyletic form in Naja genus and N. kaouthia is the closest species with N. siamensis based on partial 16S rRNA and ND1 gene.
Keyword: 16S rRNA, Elapidae, ND1, phylogenetic relationship