Judul: Isolasi Selulosa Ampas Sagu dengan Delignifikasi Menggunakan Hidrogen Peroksida
Abstrak: Isolation of cellulose from sago waste has been successfully performed in this research. Through several steps, namely removal of extractive compounds, removal of starch, and removal of hemicellulose. The starch removal from free-extractive sample by extraction with water at 80 °C required a lot of water and time. By using HCl 3% at 80 °C, less time was needed. The yield of free-starch samples obtained from hot water extraction was 41.5%, higher than the product of HCl 3% extraction, which was 26.3%. Cellulose was also hydrolized with HCl 3%, in accordance with the appearance of C=O absorption in the fourier transform infrared (FTIR) spectrum. Lignin content after delignification with 0.75, 1, and 1.5% H2O2 were 22.2, 18.7, and 14.6% while the yield were 43.6, 41.4, and 39.4%, respectively. FTIR spectrum of cellulose isolated with starch removal method using water was more similar to the commercial cellulose than cellulose which starch removal method used HCl 3%.
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Judul: Cellulose Benzoate Stationary Phase from Non-Fiber Sago Waste for Separation of Java Turmeric Active Components.
Abstrak: Pengolahan sagu di Indonesia menghasilkan pati sebagai produk utama dan juga limbah ampas sagu. Limbah ampas sagu terdiri atas fraksi serabut dan non-serabut. Penelitian ini memanfaatkan ampas sagu non-serabut untuk diisolasi selulosanya kemudian dimodifikasi menjadi barang yang lebih ekonomis. Selulosa diisolasi dengan menghilangkan kandungan senyawa lain seperti pati dan lignin. Penghilangan pati dilakukan dengan HCl 3% dan lignin dengan pulping menggunakan NaOH 20% dilanjutkan dengan pemucatan (bleaching) dengan H2O2 5%. Selulosa hasil bleaching ditambahkan HCl 2.5 N lalu diesterifikasi menggunakan benzoil klorida dalam piridina pada suhu 60 °C dengan variasi waktu 4, 6, dan 8 jam. Produk esterifikasi ialah selulosa benzoat. Pembentukan selulosa benzoat dipantau dengan analisis gugus fungsi menggunakan spektrofotometer inframerah transformasi Fourier. Derajat substitusi tertinggi sebesar 1.8807 diperoleh dari esterifikasi selama 8 jam. Selanjutnya selulosa benzoat diuji ketahanannya terhadap pelarut organik, dan ketahanan paling baik terlihat pada pelarut metanol. Elusi ekstrak temu lawak dengan eluen metanol dalam kromatografi kolom berbasis selulosa benzoat menunjukkan peningkatan kadar xantorizol dan kurkuminoid dibandingkan dengan ekstrak awal.
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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