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: A Continuous Vaccination Strategy in the SVIR Epidemic Model
Abstrak: Vaccination is conducted to minimize the spread of a disease. The vaccination is usually done several times within a fixed time interval. In the SVIR model, it is assumed that individuals do not get immediate immunity following a vaccination program. So according to process of vaccination on SVIR model, there are two strategies, i.e. the continuous vaccination strategy (CVS) and the pulse vaccination strategy (PVS). In this study, only the CVS strategy in epidemic model SVIR is considered. Results of the study indicate that dynamics of the CVS system depends on the basic reproductive number. If the basic reproductive number is less than one, then the disease-free fixed point is asymptotically stable. It means that the disease will eventually disappear from the population. Conversely, if the basic reproductive number is greater than one, then the endemic fixed point is asymptotically stable, which means that the disease will remain exist in the population. Simulation result shows that the vaccination would minimize the spread of disease by reducing the basic reproductive number. If the time for the vaccinated recipients to obtain the immunity, as well as a possibility of vaccinated recipients to be infected are neglected, then the disease will be eradicated. This condition is called an over-evaluating effect of vaccination.
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