Judul: Karakteristik Oriented Strand Board Hibrida Strand Sengon dan Mangium dengan Perlakuan Steam pada Berbagai Tingkat Kerapatan Papan
Abstrak: Oriented Strand Board (OSB) merupakan produk yang dapat memanfaatkan kayu fast growing species dan bahan baku secara efisien. Kombinasi bahan baku dan perlakuan pendahuluan steam diterapkan untuk meningkatkan kualitas papan. Penelitisn ini adalah untuk mengevaluasi karakteristik OSB hibrida strand Sengon dan Mangium dengan perlakuan steam pada berbagai tingkat kerapatan papan. Strand Sengon (Paraserianthes falcataria) dan Mangium (Acacia mangium) diberi perlakuan pendahuluan steam. Papan OSB hibrida dibuat dengan kerapatan target 0.6 g.cm-3, 0.65 g.cm-3, dan 0.7 g.cm-3. Papan OSB hibrida dibuat tiga lapis dengan nisbah lapisan (25/50/25) dan perekat phenol formaldehyde (PF) (SC = 49.95%) 10%. OSB hibrida berhasil dibuat dengan kerapatan sesuai dengan kerapatan target. Peningkatan kerapatan papan menyebabkan peningkatan sifat fisis dan mekanis OSB hibrida. OSB hibrida dengan kerapatan 0.7 g.cm-3merupakan OSB hibrida dengan kualitas terbaik.
Keyword: kerapatan, Mangium, oriented strand board hibrida, Sengon, steam

Judul: Karakteristik Oriented Strand Board Hibrida Kayu Sengon dan Bambu Betung pada Berbagai Kerapatan Papan
Abstrak: Oriented Strand Board (OSB) is a potential composite product to be developed. The combination of wood strand and bamboo strand as hybrid OSB raw materials is expected to produce better OSB characteristics. The density value affects the quality of OSB, so it is necessary to know the optimum density value of hybrid OSB. This study aims to analyze the characteristics of hybrid OSB Sengon wood (Paraserianthes falcataria) and Betung bamboo (Dendrocalamus asper) on various board densities. Sengon wood strand and Betung bamboo strand were treated by steam at 126 ºC temperature and under 0.14 MPa pressure for an hour. Betung bamboo strands were then washed with a solution of 1% NaOH. Hybrid Oriented strand boards were made with a size of (30x30x0.9) cm3 and 0.6 g.cm-3, 0.65 g.cm-3, dan 0.7 g.cm-3 target densities using 10% of phenol formaldehyde adhesive. Sengon wood strands were used in the face and back layers while Betung bamboo strands were used in the core layer with comparison of 25:50:25 (face:core:back). Determination of hybrid OSB Sengon wood and Betung bamboo characteristics were referred to JIS A 5908: 2003 about particleboard and the values was compared to CSA 0437.0 (Grade O-1) standards about OSB design manual. The results showed that the density affects the physical and mechanical properties values of hybrid OSB. The physical and mechanical properties were improved with increasing the board density. OSB with density 0.65 g.cm-3 and 0.7 g.cm-3 have good physical and mechanical properties based on CSA 0437.0 (Grade O-1) standard.
Keyword: Betung bamboo, density, hybrid oriented strand board, Sengon

Judul: Dynamical System of Hepatitis B in Three Groups with Vaccination
Abstrak: The aim of this study is to modify the hepatitis B transmission model in three age groups involving vaccination from the model conducted by Zhoe and Zhang.The method used is to analyze the stability of the fixed point and its basic reproduction number (R_0). Performed stability analysis and numerical simulation to see population dynamics. Next, a sensitivity analysis of the parameters was carried out to see its effect on R_0. From the analysis obtained two fixed points, namely non-endemic and endemic fixed points. Non-endemic fixed points are locally asymptotically stable if R_0 <1 Meanwhile, the endemic fixed point is locally asymptotically stable if R_0 > 1. Hepatitis vaccination affects the number of susceptible population, because the more successful the vaccination, the smaller the number of susceptible populations so that the smaller the population will be infected.
Keyword: Dynamic, Hepatitis B, Vaccine, Mathematical model