Judul: Pencirian Film Bioplastik Antimikrob dari Kitosan-Poliasam Laktat.
Abstrak: Meningkatnya penggunaan plastik kemasan nondegradabel menyebabkan permasalahan lingkungan. Pengembangan plastik degradabel atau bioplastik menjadi salah satu alternatif penyelesaian masalah tersebut. Kitosan merupakan salah satu bahan bioplastik yang dapat digunakan sebagai kemasan. Film bioplastik yang terbuat dari kitosan memiliki sifat barrier yang rendah. Untuk memperbaiki hal tersebut, dalam penelitian ini dibuat film dari campuran kitosan-PLA dengan nisbah 10:0; 9:1; 8:2; 7:3; dan 0:10. Film yang didapatkan diuji kuat tarik, persen pemanjangan, titik leleh, permeabilitas uap air, dan aktivitas antimikrobnya. Interaksi antarkomponen penyusun dicirikan dengan spektrofotometer inframerah transformasi Fourier (FTIR), struktrur permukaan film diamati menggunakan mikroskop pemayaran elektron. Film campuran kitosan-PLA memiliki kuat tarik dan persen pemanjangan yang semakin rendah dengan meningkatnya nisbah PLA. Spektrum FTIR menunjukkan interaksi antara kitosan dan PLA terjadi secara fisik. Sifat barrier film kitosan-PLA menurun. Film bioplastik kitosan-PLA memiliki titik leleh lebih rendah daripada komponen penyusunnya. Permukaan film kitosan-PLA terlihat kurang homogen. Film campuran kitosan-PLA mampu menghambat baik bakteri Gram positif maupun negatif.
Keyword: antimikrob, bioplastik, kitosan, PLA, sifat mekanik

Judul: Pencirian Film Bioplastik dari Tepung Tapioka Terplastisasi Gliserol dengan Penambahan Kitosan
Abstrak: Non-biodegradable synthetic plastic is widely used as packaging. However, the plastic waste can pollute the environment so that bioplastics are developed, which are easily degraded. In this research, packaging films have been made from glycerol and tapioca starch blends with composition ratio of 8:2 and 7:3 as well as various concentrations of chitosan 1, 2, and 3%. The plastics produced were analyzed for the mechanical properties by using tensile strength test, density, functional groups based on Fourier transform infrared spectrophotometer, surface morfology with scanning electron microscope, and thermal properties from differential scanning calorimeter. Addition of plasticizer was found to lower the density. Plastic with 8:2 ratio and addition of 2% chitosan yielded tensile strength 304 MPa and elongation 37%. Functional groups analysis showed that the film was a result of physical mixing. The plastic’s surface was quite homogenous and the melting point was increased with addition of chitosan. Addition of chitosan could increase the mechanical properties and was expected to be easily degradated in the environment.
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Judul: Query Expansion based on Bilingual Dictionary Using Conditional Probability
Abstrak: Query expansion is a technique that can be used to bridge vocabulary gaps between queries and documents in the collection. With query expansion, user will be helped to formulate queries well so that user will optimize the search result. In this study, the expansion term was resulted from the translation of bilingual dictionary. Subsequently, several terms of expansion were elected based on the closeness of its relationship with the original query. This research showed that conditional probability can be used to select expansion term in bilingual translation method query expansion. The result of 1000 documents was more than 97% relevan document can be retrieved by this system. The more expansion term used, the larger number relevan document was retrieved.
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