Judul: Evaluation of the Physical Properties and  Anatomical Structure of Sengon (Falcataria moluccana) Wood after Multistage of  Delignification
Abstrak: Perubahan iklim akibat emisi gas rumah kaca menjadi salah satu tantangan terbesar yang perlu diantisipasi. Salah satu langkah proaktifnya adalah dengan mengembangkan material maju yang berpotensi sebagai material penangkap dan penyimpan karbon. Kunci keberhasilan pembuatan material maju tersebut terletak pada optimalisasi proses delignifikasi yang diaplikasikan. Tujuan penelitian adalah menganalisa sifat fisis dan struktur anatomi kayu sengon (F. moluccana) setelah didelignifikasi bertingkat yang meliputi delignifikasi menggunakan larutan NaOH dan Na2SO3 pada suhu 100 ºC selama 8, 9 dan 10 jam; lalu dilanjutkan dengan delignifikasi dalam H2O2 pada suhu 100 ºC selama 1 dan 3 jam; kemudian dibekukan pada suhu –20 ºC selama 24 jam dan di freeze-dry pada suhu –53 ºC selama 48 jam. Dibandingkan kayu kontrol, hasil penelitian menunjukkan kerapatan kayu hasil delignifikasi bertingkat cenderung lebih rendah, diameter porinya lebih besar dan warnanya lebih cerah (menjadi putih kekuningan). Hasil FTIRnya memperlihatkan adanya penurunan panjang gelombang pada rentang 1032–3352 cm-1 yang mengindikasikan telah terdegradasinya komponen kimia kayu terutama hemiselulosa dan lignin., Climate change due to greenhouse gas emissions is one of the biggest challenges that needs to be anticipated. One proactive step is to develop advanced materials from wood that have the potential to be used as carbon capture and storage. The key to the success of making this material lies in optimizing the delignification process applied. The aim of this research was to analyze the physical properties and anatomical structure of sengon (F. moluccana) wood after multilevel delignification which includes delignification using NaOH and Na2SO3 solutions at a temperature of 100 ºC for 8, 9 and 10 hours; continued with delignification in H2O2 solution at a temperature of 100 ºC for 1 and 3 hours; then frozen at –20 ºC for 24 hours and freeze-dried at –53 ºC for 48 hours. Compared to control wood, the research results show that the density of wood resulting from multilevel delignification tends to be lower, the pore diameter is larger and the color is brighter (becomes yellowish white). The FTIR results show a decrease in wavelength in the range 1032–3352 cm-1, which indicates the degradation of wood chemical components, especially hemicellulose and lignin.
Keyword: anatomical characteristics, multistage delignification, physical  properties, sengon, wood aerogel

Judul: Physical, Mechanical Properties and Durability of Impregnated Sengon Wood by Nano Silica orignated from Betung Bamboo Leaves
Abstrak: Sengon (Falcataria moluccana Miq.) merupakan jenis kayu cepat tumbuh yang memiliki beberapa kelemahan, yaitu berat jenis, kekuatan, keawetan, kerapatan dan stabilitas dimensi yang rendah. Penelitian ini bertujuan untuk menganalisis pengaruh perlakuan impregnasi menggunakan monoethylene glycol (MEG) dan nano silika daun bambu betung terhadap sifat fisis, mekanis dan keawetan kayu sengon. Salah satu metode modifikasi kayu adalah impregnasi. Proses impregnasi memiliki keunggulan yaitu dapat meningkatan kerapatan dan kekerasan kayu dengan memasukkan polimer ke dalam struktur kayu. Larutan impregnasi yang digunakan yaitu kontrol (tanpa perlakuan), MEG, MEGSilika 0.5% 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. Hasil penelitian menunjukkan perlakuan impregnasi MEG dan nano silika berpengaruh nyata dan meningkatkan nilai weight percent gain (WPG), kerapatan, perubahan warna (ΔΕ), MOE, MOR, kekerasan dan persentase mortalitas rayap tanah Coptotermes curvignathus serta menurunkan persentase kehilangan berat pada kayu sengon. Secara keseluruhan perlakuan MEGSilika 1% merupakan perlakuan yang paling optimum untuk kayu sengon yang berumur 5 tahun, Sengon (Falcataria moluccana Miq.) is fast growing wood species which has inferior characteristics i.e. low specific gravity, strength, durability, density and dimensional stability. The objective of this study was to analysis the effect of monoethylene glycol (MEG) and nano silica originated from betung bamboo leaves impregnation treatment on physical, mechanical properties and durability of sengon wood. One of wood modification methods is impregnation. Impregnation process could increase the wood density and hardness by introducing polymer into wood structure. The impregnation solution were consisted of water treated (untreated), MEG, MEGSilika 0.5% and MEGSilika 1%. The impregnation process was initiated by applying 0.5 bar of vacuum for 60 min and followed by 2.5 bar of pressure for 120 min. The results showed that MEG and nano silica impregnation treatment had significant effect on and increased weight percent gain (WPG), density, color changes (ΔΕ), MOE, MOR, hardness and mortality percentage of termite Coptotermes curvignathus and decreased weight loss percentage. MEGSilika 1% was the optimum treatment for of 5-year-old sengon wood.
Keyword: daun bambu betung, impregnasi, keawetan, nano silika, sengon, betung bamboo leaves, durability, impregnation, nano silica

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