Judul: Pengaruh Konsentrasi Natrium Tripolifosfat (STP) Terhadap Rendemen dan Mutu Tepung Agar-agar dari Rumput Laut Gracilaria verrucosa
Abstrak: Seaweed is one of the plants, including Thallopyta Division is containing polysaccharides that are not found in other plants, and it is available in large quantities. The purpose of this study was to use seaweed as a compactor on plant tissue culture media using sodium tripolyposphat as raw material on extraction agar powder. The study was conducted in two stages. A preliminary research was conducted to determine the chemical composition of raw materials, as well as to find the apropriate tripolyposphat sodium concentration that will be used in the main research. Primary research was conducted to look for extraction time and apropiate water added to the extraction process. Parameters that observed in the agar powder production is yield and gel strength. The results showed that Sodium Tripoliphosphate has significant effect on the extraction process toward gell strength, and extraction time. Water added has influence on yield significant toward agar powder.
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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