Judul: A Review of the Difference of Physical and Mechanical Bioplastic Properties from Seaweed Hydrocolloids with Various Plasticizers
Abstrak: Hidrokoloid rumput laut seperti alginat dan karaginan yang diekstrak dari rumput laut cokelat dan merah memiliki potensi untuk dikembangkan menjadi bioplastik. Bioplastik merupakan polimer plastik dari bahan alami yang bersifat biodegradasi. Bioplastik berbahan dasar alginat dan karaginan memiliki sifat rapuh dan tidak elastis. Plasticizer seperti asam asetat, gliserol, sorbitol, dan polietilen glikol dapat ditambahkan pada bahan pembuat plastik untuk mengatasi sifat rapuh dan tidak elastis tersebut. Tujuan dari penelitian ini mengetahui perbedaan sifat fisik dan mekanik bioplastik dari hidrokoloid rumput laut dengan beragam penambahan plasticizer. Data yang digunakan pada kajian literatur ini diambil dari beberapa jurnal nasional terakreditasi dan jurnal internasional. Data disajikan secara kuantitatif dan disintesis secara naratif untuk menjawab hipotesis. Hasil yang diperoleh yaitu penambahan pemberian plasticizer pada bioplastik dapat merubah sifat fisik dan mekanik bioplastik sebelum ditambahkan plasticizer. Ketebalan dan elongasi bioplastik mengalami peningkatan setelah ditambah plasticizer. Namun pada kuat tarik bioplastik mengalami penurunan setelah diberi penambahan plasticizer.
Keyword: alginate, carrageenan, hydrocolloids, plasticizers

Judul: Bioplastic characterization of cassava starch with addition of sodium alginate, cellulose, and limonene
Abstrak: Penggunaan plastik sintetik meningkat setiap tahunnya, namun plastik yang beredar menghasilkan limbah yang sulit terurai sehingga dibuat plastik yang ramah lingkungan. Dalam penelitian ini, bioplastik dibuat dengan paduan tepung singkong dan gliserol dengan nisbah komposisi 75:5 serta beragam konsentrasi natrium alginat, limonena dan selulosa. Bioplastik yang dihasilkan dianalisis bobot jenis, sifat mekanik, permeabilitas uap air, sifat termal, dan morfologi permukaannya. Penggunaan natrium alginat dan selulosa meningkatkan kuat tarik dan bobot jenis. Limonena hasil ekstraksi kulit jeruk meningkatkan elongasi bioplastik dan menurunkan permeabilitas uap air. Analisis termal dengan kalorimeter pemayaran diferensial menghasilkan nilai titik leleh yang meningkat dengan tambahan natrium alginat. Bioplastik yang dihasilkan memiliki morfologi permukaan yang homogen., There is high demand of sintetic plastic production each year, but the use of plastic produces non biodegradable wastes. Therefore, biodegradable plastics can be an alternative solution to overcome the problem in relating with the need of environmentally friendly plastics. Theaim of this study was to characterized bioplastics made of cassava starch with addition of sodium alginate, cellulose, and limonene. Bioplastics were made of composit of cassava starch and gliserol (75:5) and various concentrations of sodium alginate: limonen:celullose. The analysis of density, mechanical properties, thermal analysis, water vapour permeability and morfology were conducted for the biodegradable plastics. The results showed that sodium alginate and celullose increased the tensile strength and density. Limonene extracted from orange peels increased percentage of elongation and the thickness, also decrease the water vapour permeability. Thermal analysis using differential scanning calorimeter showed that sodium alginate addition increased the melting point and it indicated interaction among constituents. The surface morfology of bioplastics composite in thies study showed homogenous character. Keyword: bioplastic, cellulose, limonene, sodium alginate
Keyword: bioplastik, limonena, natrium alginat, selulosa

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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