Judul: Pemisahan dan Pencirian Amilosa dan Amilopektin dari Pati Jagung dan Pati Kentang pada Berbagai Suhu
Abstrak: Amilose can be separated from amylopectin based on their distinct properties. Amylose is more crystaline, while amylopectin is amorphous. Separation was done by heating a solution of corn and potato with a ratio of 1:30, 1:45, 1:60 at 53, 55, 57oC for potato starch and 60, 70, 72 oC for corn starch for 1.5 hours. The results showed that amylose could be separated from amylopectin simply by using hot water. The results showed that temperature wais more influencing on the separation of amylose-amylopectin. The best separation results were at 60 °C and the ratio of 1:60 for corn starch with molecular weight 5.6919 × 105 g/mol for amylose and 81.2783 × 105 g/mol for amylopectin and at a temperature of 53 °C and the ratio of 1:60 for potato starch with molecular weight 4.2688 × 105 g/mol for amylose and for amylopectin 61.6797 × 105 g/mol. The temperature and the ratio of amylose : amylopectin obtained were closely similiar to those published in literatures. From the results obtained by DSC measurements the glass transition point at 1:60 ratio was at 70.10 oC for potato starches at temperature 57 oC and 40.76 oC for corn starch at 72 oC.
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Judul: Pemisahan dan Pencirian Amilosa-Amilopektin pada Tepung Tapioka dan Sagu Menggunakan Ragam Suhu Air
Abstrak: Amylose can be easily separated by using water with several temperature condition. Separation amylose and amylopectin process is done by using not only hot water with different temperature 55, 60,and 65 °C, but also with different rasio 1:30, 1:45, and 1:60. The characteristics that observed in this study were water contain, viscosity, molecular weight, and thermal analysis using differential scanning calorymeter. The yield of amylose from tapioca obtained in this study were 15−17% (60 °C), and 21−23% (65 °C) but there is no yield obtained on 55 °C, meanwhile the yield of amylose from sagoo obtained were 13−16% (60 °C), and 22−23% (65 °C). The characteristics of amylose and amylopectin, both obtained from tapioca and sagoo had met standard range so there is no purified anymore.
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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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