Judul: Kajian penggunaan NaOCl dan kaporit pada pemucatan natrium alginat dari rumput laut cokelat (Sargassus polycystum)
Abstrak: Seaweed which is commonly found is mainly from red algae, green algae, and brown algae. Unfortunately, the utilization of seaweed in Indonesia has not been deeply explored. One product that can be obtained from seaweed extraction is alginate. Alginate can be extracted from Alginophyt plant, a group of brown seaweed (Phaeophyceae). Seaweed from brown algae contains approximately 20% of alginate. This compound is the main component of brown algae's cell wall and can be commercialized as gel, filler, stabilizer, emulsifier as well as basic ingredient in food processing, pain industry, pharmacy, and as explosive material. Sodium alginate is water soluble and has high commodity value. Based on Food grade and Pharmaceutical grade, degree of whiteness is one of the most important factors to determine the quality of sodium alginate.
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Judul: Bleaching Process Design in the Production Process of Sodium Alginate from Brown Seaweed (Sargassum sp.).
Abstrak: Perendaman rumput laut cokelat dalam natrium karbonat dapat menghasilkan ekstrak alginat, yang kemudian dapat diubah menjadi asam alginat dengan penambahan asam. Namun komponen warna kromofor terbentuk selama proses ekstraksi. Hal ini menghasilkan produk natrium alginat dengan kualitas yang rendah. Penambahan NaOCl dapat mengoksidasi komponen zat warna kromofor yang terekstraksi sehingga dapat meningkatkan kualitas produk natrium alginat. Penelitian ini bertujuan untuk meningkatkan kualitas produk natrium alginat melalui desain proses pemucatan dari hasil ektraksi secara alkali dari rumput laut cokelat. Proses pemucatan natrium alginat dilakukan dengan penambahan larutan NaOCl 10% sebanyak 0%, 10%, dan 20% dari filtrat alginat. Produk natrium alginat dievaluasi parameter antara lain, rendemen, kadar abu, kadar air, nilai pH, viskositas, dan derajat putih. Proses yang terpilih adalah penambahan NaOCl 10% sebesar 10%, yang menghasilkan karakteristik rendemen 13.79 ± 2.67%, viskositas 45.00 ± 7.07 cPs, derajat putih 35.75 ± 1.64 %, kadar air 7.04 ± 0.09 %, pH 8.75 ± 0.85 %, dan kadar abu 31.10 ± 1.20 %. Kata Kunci : Sargassum sp. natrium alginat, ekstraksi alkali, pemucatan, NaOCl
Keyword: Sargassum sp, sodium alginate, alkaline extraction, bleaching, NaOCl

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