Judul: Pembuatan dan Pencirian Polipaduan Poliasamlaktat-Lilin Lebah
Abstrak: Nondegradable plastic waste could cause an environment problem due to its difficulty in degradation. The development of biodegradable polylacticacid (PLA)-beeswax polyblend is necessary to give alternatives of nondegradable plastic. PLA-beeswax polyblend were produced by mixing PLA and beeswax solution with various compositions namely 40:60, 50:50, 60:40, 70:30, and 80:20 by weight. The polyblends were tested for their tensile strength, density, fourier transform infrared spectroscopy (FTIR), and scanning electron microscope (SEM). PLA-beeswax polyblends were white in color. Tensile strength, elongation, and density increases as increasing of PLA constituents. FTIR spectrum of polyblend PLA-beeswax 80:20 did not show any new functional groups, meaning that the film was merely a physical mixture. Structure of the polyblend film revealed a homogenous film.
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Judul: Pencirian Plastik Antioksidan Paduan Poli(asam laktat)-Lilin Lebah dengan Penambahan Pemlastis Polietilena Glikol
Abstrak: The use of conventional plastics for packaging food has caused environmental and health problems. Antioxidant plastic poly(lactic acid) (PLA) and beeswax blend with polyethylene glycol addition as plasticizer can be a potential alternative for preparing biodegradable plastic. PLA-beeswax blend plastics were produced from PLA and beeswax solution with various compositions, i.e. 40:60, 50:50, 60:40, 70:30, and 80:20 by weight with polyethylene glycol level of 0,005; 0,01; and 0,02 g. The analysis was performed to measure density, tensile strength, morphological, and functional groups. Tensile strength, elongation, and density increases with the increasing PLA constituents. Functional group analysis showed a physical interaction. Plastic morphological results showed a good homogenous properties. PLA-beeswax ratio of 80:20 with the composition of polyethylene glycol 0,01 g produced the best mechanical properties.
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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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