Judul: Physical Properties and Color Changes in Polystyrene Impregnated Mangium (Acacia mangium) Glulam
Abstrak: Glue Laminated Timber (Glulam) merupakan salah satu produk komposit dari kayu. Tujuan penelitian ini untuk mengetahui pengaruh impregnasi polistirena terhadap sifat fisis dan perubahan warna glulam dari kayu mangium (Acacia mangium). Tujuan perlakuan impregnasi untuk peningkatan sifat fisis kayu dengan cara memasukkan monomer stirena ke dalam kayu. Evaluasi karakteristik yang dilakukan adalah polymer loading, kerapatan, kadar air, delaminasi, dan perubahan warna. Hasil penelitian menunjukkan bahwa nilai rata-rata polymer loading, kerapatan, kadar air, delaminasi, dan perubahan warna masing-masing adalah 5,25 %, 0,69-0,80 g·cm-3, 10,07-11,58 %, 6,4-19,69 %, dan 7,04. Pembuatan glulam impregnasi polistirena kayu mangium dapat meningkatkan sifat fisis pada glulam. Nilai kerapatan tertinggi dan kadar air terendah didapatkan pada glulam impregnasi polistirena. Impregnasi polistriena memberikan pengaruh yang berbeda (different colors) terhadap perubahan warna kayu mangium. Warna kayu menjadi lebih gelap setelah terimpregnasi polistirena. Nilai delaminasi glulam impregnasi polistirena tidak sesuai standar., Glue Laminated Timber (Glulam) is a composite product made of wood. The purpose of this study was to determine the effect of polystyrene impregnation on the physical properties and color changes of glulam from mangium (Acacia mangium). The purpose of impregnation treatment is to improve the physical properties of wood by incorporating styrene monomer into the wood. Characteristic evaluation carried out were polymer loading, density, moisture content, delamination, and color change. The results showed that the average values of polymer loading, density, moisture content, delamination, and color change were 5.25%, 0.69-0.80 g·cm-3, 10.07-11.58 %, 6.4-19.69%, and 7.04. The manufacture of glulam impregnation of mangium wood polystyrene can improve the physical properties of the glulam. The highest density values and the lowest water content were found in polystyrene impregnated glulam. Polystyrene impregnation has a different effect (different colors) on the color change of mangium wood. The color of the wood becomes darker after being impregnated with polystyrene. The delamination value of polystyrene impregnated glulam is not up to standard.
Keyword: fast growing wood, glulam, impregnation, isocyanate, mangium

Judul: Physical and Mechanical Properties of Polystyrene Impregnated Glulam in Manii
Abstrak: Glulam (glued laminated timber) merupakan salah satu produk biokomposit yang dapat digunakan untuk mengatasi penggunaan kayu cepat tumbuh pada hutan tanaman. Kayu manii (Maesopsis eminii) merupakan salah satu jenis kayu cepat tumbuh yang dapat dimanfaatkan sebagai bahan baku glulam. Glulam dengan bahan baku kayu cepat tumbuh memiliki sifat fisis dan mekanis yang rendah. Untuk memperbaiki sifat fisis dan mekanis glulam kayu manii dapat dilakukan dengan impregnasi polistirena. Tujuan dalam penelitian ini adalah untuk mengetahui pengaruh proses impregnasi polistirena terhadap sifat fisis dan mekanis glulam dari kayu manii. Parameter sifat fisis dan mekanis yang diukur pada penelitian ini adalah kadar air, kerapatan, MOE, MOR, keteguhan geser, dan kekerasan. Nilai polymer loading yang terpolimerisasi dalam kayu sebesar 9,19%. Nilai kadar air berkisar antara 8,76 - 12,9%. Nilai kerapatan berkisar antara 0,42 - 0,47 g·cm-3. Nilai MOE berkisar antara 46607 - 66216 kg·cm-2. Nilai MOR berkisar antara 457 - 604 kg·cm- 2. Nilai keteguhan geser berkisar antara 67,91-46,08 kg·cm2. Nilai kekerasan berkisar antara 185 - 309 kg·cm-2. Nilai delaminasi glulam terimpregnasi polistirena lebih rendah dibanding glulam kontrol sebesar 6,22%. Secara keseluruhan hasil perlakuan impregnasi polistirena dapat meningkatkan sifat fisis dan mekanis glulam kayu manii., Glulam (glued laminated timber) is one of the biocomposite products that can be used to overcome the use of fast-growing wood in plantation forests. Manii (Maesopsis eminii) is a fast-growing species that can be used as raw material for glulam. Glulam with fast-growing species as raw material has low physical and mechanical properties. To improve the physical and mechanical properties of manii glulam can be done with polystyrene impregnation. The purpose of this study was to determine the effect of the polystyrene impregnation process on the physical and mechanical properties of glulam from manii wood. Parameters of physical and mechanical properties measured were moisture content, density, MOE, MOR, shear strength, and hardness. The polymer loading value in wood is 9.19%. The value of moisture content ranges from 8.76 - 12.9%. Density values ranged from 0.42 - 0.47 g·cm-3. MOE values ranged from 46607 - 66216 kg·cm-2. MOR values ranged from 457 - 604 kg·cm-2. The value of shear strength ranged from 67.91 - 46.08 kg·cm-2. Hardness values ranged from 185 - 309 kg·cm-2. The delamination value of polystyrene impregnated glulam was lower than that of control glulam by 6.22%. Overall the results of polystyrene impregnation treatment can improve the physical and mechanical properties of manii glulam.
Keyword: glulam, impregnation, isocyanate, manii wood, polystyrene

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