Judul: Characteristics of Impregnated Fast Growing Woods by Nano Silica Orignated from Betung Bamboo Leaves and  Monoethylen Glycol.
Abstrak: Sengon (Paraserianthes falcataria L. Nielsen.) dan Jabon (Anthocephalus cadamba Miq.) merupakan jenis pohon cepat tumbuh yang memiliki nilai kekuatan, keawetan, kerapatan, dan stabilitas dimensi yang rendah. Salah satu metode untuk meningkatkan nilai dari kayu cepat tumbuh yaitu dengan cara impregnasi. Proses impregnasi dimulai dengan pemberian vakum 0,5 bar selama 60 menit dan dilanjutkan dengan pemberian tekanan 2,5 bar selama 120 menit. Perlakuan MEG dan nano silika mampu meningkatkan nilai persentase weight percent gain, kerapatan, perubahan warna, modulus of elasticity, modulus of rupture, kekerasan, meningkatkan nilai mortalitas serta menurunkan persentase kehilangan berat pada pengujian rayap kayu kering, rayap tanah dan uji lapangan kayu sengon serta kayu jabon. Perlakuan MEG dan nano silika juga dapat meningkatkan kelas kuat kayu sengon yang semula berada pada kelas kuat III-IV menjadi kelas kuat III dan kelas kuat kayu jabon yang semula berada pada kelas kuat IV-V menjadi kelas kuat V. Kelas awet kayu sengon yang semula berada pada kelas awet V menjadi II dan untuk kayu jabon yang semula berada pada kelas awet V menjadi kelas awet II., Sengon (Paraserianthes falcataria L. Nielsen.) and Jabon (Anthocephalus cadamba Miq.) are fast-growing tree species that have low strength, durability, density, and dimensional stability values. One method to increase the value of fast growing wood is by impregnation. The impregnation process was started by applying a vacuum of 0,5 bar for 60 minutes and continued by applying a pressure of 2,5 bar for 120 minutes. In drywood termites, subterranean termites, and field tests of sengon wood and jabon wood, MEG and nano silica treatments were able to increase the values of weight percent gain, density, color change, modulus of elasticity, modulus of rupture, hardness, increase the mortality value, and reduce the percentage of weight loss in drywood termites and subterranean termites. MEG and nano silica treatment can also increase the strength class of sengon wood, which was originally in strong class III-IV to be strong class III, and the strong class of jabon wood, which was originally in strong class IV-V to be strong class V. Sengon wood, which was originally in durable classes V to II, and jabon wood, which was originally in durable classes V to durable class II.
Keyword: daun bambu betung, impregnasi, jabon, nano silika, sengon, bamboo betung leaves, impregnation, nano silica

Judul: Characteristic of Impregnated Fast Growing Wood Species by Nano Silica made from Leaves of Betung Bamboo.
Abstrak: Jabon (Anthocephalus cadamba Miq.) dan Sengon (Falcataria moluccana Miq.) merupakan dua jenis kayu cepat tumbuh yang memiliki beberapa kelemahan, yaitu berat jenis, kekuatan, keawetan, kerapatan, dan stabilitas dimensi yang rendah. Oleh karena itu, dibutuhkan suatu teknologi yang dapat meningkatkan kualitas kayu cepat tumbuh yaitu dengan modifikasi kayu. Salah satu metode modifikasi kayu adalah impregnasi. Proses impregnasi memiliki keunggulan yaitu dapat meningkatan kerapatan dan kekerasan kayu dengan memasukkan senyawa molekul ke dalam struktur kayu. Impregnasi yang dilakukan menggunakan kombinasi Monoethylene Glycol (MEG) dan nano silika daun bambu betung. Penelitian ini bertujuan untuk menganalisis pengaruh perlakuan impregnasi MEG dan nano silika daun bambu betung terhadap kestabilan dimensi dan kerapatan kayu jabon dan sengon, serta menganalisis karakteristik kayu jabon dan sengon hasil impregnasi. Bahan-bahan yang digunakan terdiri dari kayu jabon dan sengon umur 5 tahun, daun bambu betung, MEG, PEG 6000, NH4OH, H2SO4, NaOH, dan Air demin. Silika diekstraksi dari daun bambu betung menggunakan metode refluks, kemudian dilanjutkan dengan proses sonikasi untuk menghasilkan nano silika. Kayu jabon dan sengon yang digunakan berukuran 2 cm x 2 cm x 2 cm. Larutan impregnasi yang digunakan yaitu larutan MEG, MEGSilika 0.5%, MEGSilika 0.75%, dan MEGSilika 1%. Proses impregnasi dimulai dengan pemberian vakum 0.5 bar selama 60 menit dan dilanjutkan dengan pemberian tekanan 2.5 bar selama 120 menit. Pengujian yang dilakukan meliputi stabilitas dimensi, dan kerapatan serta uji karakterisasi menggunakan PSA, SEM-EDX, XRD, dan FTIR. Hasil penelitian menunjukkan bahwa nano silika yang dihasilkan berukuran 234.49-851.36 nm, dengan ukuran rataan sebesar 472.67 nm. Perlakuan impregnasi MEG dan nano silika berpengaruh nyata terhadap stabilitas dimensi (weight percent gain, anti-swelling efficiency, water uptake, bulking effect) dan kerapatan pada kayu jabon dan sengon. Perubahan morfologi kayu jabon dan sengon hasil impregnasi ditunjukkan dengan tertutupnya noktah pada dinding vessel (hasil analisis SEM), dan terdeteksinya kandungan ethylene (hasil analisis FTIR) dan silika (hasil analisis XRD, dan FTIR). Secara keseluruhan perlakuan MEGSilika 0.75% menunjukkan perlakuan paling optimum untuk meningkatkan stabilitas dimensi dan kerapatan kayu jabon dan sengon umur 5 tahun., Jabon (Anthocephalus cadamba Miq.) and Sengon (Falcataria moluccana Miq.) are fast growing wood species which have low quality characteristics i.e. low specific gravity, strength, durability, density, and dimensional stability. Therefore, it takes a technology that can improve the quality of fast growing wood with wood modification. One method of wood modification is impregnation. Impregnation process could increase the density and hardness of wood by impregnating molecular compound into wood structure. The impregnation process that were used in this research was performed by using a combination of Monoethylene Glycol (MEG) and nano silica made from leaves of betung bamboo. The objectives of this research were to determine the effect of MEG and nano silica made from leaves of betung bamboo impregnation treatment on dimensional stability, and density, of jabon and sengon wood, and to identify the characteristics of impregnated jabon and sengon wood. Five yars old jabon and sengon were used in this study. The other materials were leaves of betung bamboo, MEG, PEG 6000, NH4OH, H2SO4, NaOH, and demineral water. Silica is extracted from leaves of betung bamboo using the reflux method, then proceed with
Keyword: Betung bamboo, Dimensional stability, Impregnation, Jabon, MEG, Nano silica, Sengon, Wood Structure, Wood Modification, FTIR Analysis, Moncethy Glycol

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