Judul: Synthesis and Application of Cellulose-g-Polyacrylamide from Sago Waste Fiber as Column Chromatography Stationary Phase.
Abstrak: Serabut ampas sagu merupakan salah satu bahan yang mengandung lignoselulosa. Selulosa dapat dimodifikasi untuk memperbaiki sifat-sifatnya, salah satunya dengan teknik pencangkokan-taut-silang. Produk modifikasi akan memiliki struktur makromolekular yang dapat diaplikasikan untuk teknologi pemisahan. Tahapan penelitian yang dilakukan terdiri atas isolasi selulosa, sintesis selulosa-g-poliakrilamida, dan aplikasi produk sebagai fase diam dalam kromatografi kolom. Isolasi selulosa menghasilkan isolat dengan kadar lignin 0.37%. Sintesis fase diam selulosa-g-poliakrilamida diaplikasikan dengan ragam jumlah penaut-silang 0.1, 0.5, dan 1.0 g. Pencirian menggunakan FTIR membuktikan telah terjadi pencangkokan akrilamida ke selulosa. Ketiga diaplikasikan pada kromatografi kolom untuk memisahkan xantorizol dari ekstrak kasar temu lawak. Berdasarkan profil kromatografi lapis tipis, xantorizol berada pada fraksi heksana pertama dan dibuktikan pula dengan kromatografi cair kinerja tinggi. Kolom terbaik untuk pemisahan xantorizol ialah selulosa-g-poliakrilamida dengan penaut-silang sebanyak 0.5 g.
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Judul: Modifikasi Sintesis dan Pencirian Fase Diam Kromatografi Kolom Selulosa Berbasis Serabut Ampas Sagu.
Abstrak: Grafting copolymerization of acrylamide (AAm) on cellulose derived from sago fibers (α-cellulose 78.61%) has been performed by using N,N'-methylene-bis-acrylamide (MBA) as cross-linker and ammonium peroxydisulfate as initiator. The cellulose-g-polyacrylamide copolymer products were characterized by their water absorption capacity, grafting ratio, and grafting efficiency as the initial characterizations. Further characterizations was carried out by using infrared spectroscopy, electron microscopy imaging, and X-ray diffraction techniques. The characterization results showed that the copolymers has been formed. Synthesis modification by sequential addition of AAm and MBA, and increased concentration of MBA reduced the water absorption capacity, whereas the grafting ratio and efficiency were increased. Copolymer products could be applied as a stationary phase for normal-phase column chromatography, based on the porous surface morphology as well as good resistance against n-hexane, n-pentane, and cyclohexane solvents.
Keyword: sago fibers, grafting, copolymerization, cellulose, acrylamide

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