Judul: Sintesis terinisiasi–mikrogelombang dan pencirian kopolimer cangkok pati sagu dengan kopolimer akrilamida dan asam 2-akrilamido-2-metilpropanasulfonat
Abstrak: Sintesis terinisiasi–mikrogelombang dan pencirian kopolimer cangkok pati sagu dengan kopolimer akrilamida dan asam 2-akrilamido-2-metilpropanasulfonat [sagu-g-poli(am-co-amps)] telah berhasil disintesis dengan metode inisiasi menggunakan mikrogelombang. Hasil sintesis berwarna putih, keras, dan higroskopis. Nisbah mol (am-amps) 7:3 memperlihatkan nisbah dan efisiensi pencangkokan tertinggi, yaitu 76% dan 84%. Keberhasilan pencangkokan dicirikan oleh spektrum yang memperlihatkan puncak serapan ulur c=o 1720–1740 cm-1 dan puncak serapan ulur n–h yang kuat dan tajam pada 1545–1560 cm-1. Puncak-puncak serapan tersebut memperlihatkan telah tercangkoknya am pada tulang punggung pati. Keberadaan gugus sulfonat dari amps dibuktikan oleh puncak serapan di 1260–1150 cm-1 untuk ulur s=o simetris dan pada 1080–1010 cm-1 untuk ulur s=o asimetris. Kenaikan kadar nitrogen memperkuat bukti bahwa am dan amps telah berhasil dicangkokkan pada pati
Keyword: akrilamida, asam 2-akrilamido-2-metilpropanasulfonat, kopolimerisasi cangkok, mikrogelombang, sagu

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