Judul: Penyiapan Bahan Baku dan Pemanfaatan Ampas Pengolahan Agar- Agar dari Gracilaria verrucosa menjadi Kertas Ramah Lingkungan
Abstrak: Preparation of raw materials for this study begins with the observation of seaweed post harvest activities include harvesting, washing, drying, and packing. Washing and drying is a combined process that most affect the quality of dried seaweed and extracted result. Agar is one of the product from Gracilaria verrucosa with the by-product’s pulp extraction process. The purposes of this study to know the preparation of raw materials, including post-harvest handling as well as physical and chemical properties of Gracilaria verrucosa and increase value-added processing of gelatinous pulp. The gelatinous residue pulp is as raw material for paper making due to its fibrous structure. Seaweed pulp was bleached using H2O2 solution with a concentration of 5% for two hours and then mixed with kaolin, tapioca, cassava, and newsprint with percentage weight 5% and 10% of the total wet weight. Formed pulp printed with size 30 cm x 20 cm. The results showed that the difference in percentage newsprint of weight addition did not significantly affect moisture content, gramatur, and print opacity of the paper. The difference in the percentage of weight increase affects only newsprint paper whiteness.
Keyword: post harvest, Gracilaria verrucosa, agar, paper

Judul: Optimasi Rendemen dan Mutu Agar-Agar dari Rumput Laut Gracilaria verrucosa dengan Metode Respon Permukaan
Abstrak: Usually, seaweed is widely used as agar. Problems that often arise in producing mainly of gelatinous seaweed Gracilaria is the difficulty of obtaining agar gel which has good characteristics such as strength, hardness and high gel cohesiveness. One reason is that there are sulfate esters in the agar. This study aims to capitalize on Gracilaria verrucosa obtained from the cultivation of the raw material for agar by analyzing the effect of adding acetic acid (CH3COOH) with a concentration of 0.5%, 1%, 1.5%, extraction temperature 85, 90, and 95 ° C and soaking time for treatment of the addition of acetic acid (CH3COOH) such as 0.5, 1, dan1.5 hours on the yield and quality of agar produced from seaweed Gracilaria verrucosa. The design of experiments using a central composite design (CCD) with the analysis carried out by analysis yield, gel strength, moisture and ash content and optimization by the response surface method. Application response surface method in extraction of agar flour in order to demonstrate that the response of yield, gel strength, moisture content, and ash content obtained at the optimum concentration of acetic acid 0.50%, 0.64 hours of soaking time and extraction temperature 89.31 ° C with a value of desirability is 0.718 obtained yield amounts 18.28%, gel strength of 99.2 gf, 15.21% moisture content and ash content 4.58%.
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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