Judul: Bioplastik komposit pati tapioka dan lilin lebah dengan tambahan natrium alginat sebagai pengemulsi
Abstrak: Bioplastic film made of tapioca starch and beeswax with addition of sodium alginate as emulsifier may be a potential alternative for biodegradable packing. The composition of tapioca starch-glycerol was fixed at 8:2. The sodium alginatebeeswax was added at various level, i.e. 19:6, 15:10, 12.5:12.5, 10:15, and 6:19. The films were analyzed for their tensile strength, density, water vapor permeability, morphology, and thermal properties. The film made of 6:19 sodium alginate and beeswax addition showed the lowest water vapor permeability, whereas the film with 19:6 sodium alginate and beeswax addition had the highest density and tensile strength, i.e. 1.5 g/mL and 4.1 MPa, respectively. The film had melting point and weight loss lower as compared to the 6:19 composition, therefore, these characteristic are not corresponding to the density due to in homogeneousity of the film. Morphology analysis showed the surface was rough and less homogeneous.
Keyword: tapioca starch., sodium alginate, glycerol, beeswax

Judul: Pencirian Edible Film Pati Tapioka Terplastisasi Sorbitol dengan Penambahan Natrium Alginat
Abstrak: Edible film made from plasticized sorbitol tapioca starch with the addition of sodium alginate is potentially used for food wrap that can maintain the food quality, edible, and environmentally friendly. The film was produced by varying the composition of tapioca starch:sodium alginate at 100:0, 95:5, 90:10, 85:15, and 80:20% with sorbitol 1% and 2% (v/v). The characterization included density, tensile strength, percent elongation, thermal properties, morphology, functional groups, water vapor permeability, and the application. The addition of sorbitol and sodium alginate could increase the edible film elongation and water vapor permeability value. The addition of sodium alginate composition to certain level would increase its tensile strength properties but the addition of sorbitol would decreased tensile strength and thermal stability. Functional groups analysis showed that the films were formed through physical interaction. The films produced were homogeneous, transparent, preserving food quality, edible and brightening food color.
Keyword: edible film, sodium alginate, tapioca starch, sorbitol

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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