Judul: Sifat Fisikokimia, Termal, dan Spektroskopi Selulosa Mikrokristalin Serabut Ampas Sagu
Abstrak: Microcrystalline cellulose (MCC) is a partially depolymerized from α-cellulose. MCC is generally used as a medicinal preparation. MCC isolates from sago waste fiber and commercial MCC (MCCK) were characterized based on physicochemical, thermal, and spectroscopic properties. MCC1 was isolated through hydrolysis, pulping, and bleaching stages while MCC2 was isolated by pulping, bleaching, and hydrolysis steps, respectively MCC1 and MCC2 yields were 13% and 6.5% with α-cellulose levels of 78.61% and 73.08%. Physicochemical properties results of all three MCCs were in accordance with MCC’s standard. MCC1 and MCCK had degree of polymerizations fulfilling MCC’s standard (􀵑���350) while for MCC2, the value was over 700. Infrared spectra of MCC1 and MCCK were also in accordance with MCC’s standard, whereas the MCC2 spectrum still showed the presence of lignin. Based on thermal analysis, MCC2 had the highest degradation temperature and degree of crystallinity, which were 396.26 °C and 66.4%, respectively, corresponding to the high lignin content. MCC1 had the largest surface area, enable to bind more active ingredient medicine.
Keyword: cellulose, microcrystalline, sago

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