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: Effect of carrageenan and gelatin addition on the characteristics of starch-based bioplastics
Abstrak: Bioplastik terbuat dari bahan yang bersifat biodegradable seperti pati, karet, kitosan, selulosa, lignin serta beberapa bagian dari hewan seperti kasein, protein, dan lipid. Penelitian ini bertujuan mengetahui formula terbaik dari gelatin dan karaginan sebagai bahan pembuatan bioplastik berbasis pati serta karakteristik sifat fisikokimia material bioplastik dari blending polimer antara pati, karaginan, dan gelatin. Pembuatan bioplastik dilakukan dengan perlakuan rasio gelatin dan karaginan yakni 1:1, 1:4, dan 4:1, dipanaskan menggunakan magnetic stirrer dengan suhu 70°C selama 25 menit. Penambahan karaginan dan gelatin berpengaruh secara signifikan terhadap kuat tarik, ketebalan, dan daya serap air bioplastik yang dihasilkan. Perlakuan terbaik yang digunakan yaitu perbandingan gelatin dan karaginan sebesar 1:4. Karakteristik yang dihasilkan memiliki nilai kuat tarik sebesar 25.85 MPa, elongasi sebesar 60%, ketebalan 0.28 mm, daya serap air sebesar 49.02%, serta memiliki nilai derajat putih sebesar 82.45%., Bioplastics are made from biodegradable materials such as starch, rubber, chitosan, cellulose, lignin and animal parts such as casein, protein and lipids. This research aims to determine the best formula of gelatin and carrageenan as ingredients for making starch-based bioplastics and the characteristics of bioplastics from mixing polymers between starch, carrageenan, and gelatin. Treatment in bioplastics is made from a ratio of gelatin and carrageenan that is 1:1, 1:4, and 4:1, heated with a magnetic stirrer at 70°C for 25 minutes. The addition of carrageenan and gelatin significantly affected the tensile strength, thickness, and water absorption of the bioplastics. The best treatment used is the ratio of 1: 4 gelatin and carrageenan. The resulting characteristics have a tensile strength value of 25.85 MPa, 60% elongation, 0.28mm thickness, 49.02% water absorption, and a white degree value of 82.45%.
Keyword: bioplastics, carrageenan, gelatin, characteristics

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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