Judul: Edible film based on carrageenan, bacterial cellulose, and nanocarbon with additional crosslinker Fe2+
Abstrak: Edible film dari karaginan merupakan lapisan tipis yang terbuat dari bahan yang dapat dikonsumsi. Aplikasi edible film pada pelapisan makanan bermanfaat untuk menambah masa simpan makanan dan melindungi makanan dari mikroorganisme berbahaya. Penambahan selulosa, gliserol, nanokarbon, dan penaut silang Fe2+ bertujuan memperbaiki sifat mekanik dan permeabilitas uap air. Nanokarbon pada edible film akan memancarkan warna saat disinari ultraviolet pada panjang gelombang 366 nm. Konsentrasi nanokarbon yang digunakan berturut-turut 0.5%, 1%, 1.5%, dan 2% b/v. Nilai kuat tarik dan permeabilitas uap air meningkat seiring meningkatnya konsentrasi nanokarbon yang diberikan. Penaut silang Fe2+ yang digunakan berturut-turut 1.5%, 3%, dan 5% b/v dengan nilai kuat tarik optimum pada konsentrasi 5%. Keberadaan karaginan dalam film ini ditunjukkan oleh spektrum inframerah pada bilangan gelombang 1234.44 cm-1 yang merupakan ciri khas karaginan, yaitu gugus fungsi fungsi ester sulfat. Kata kunci: karaginan, nanokarbon, penaut silang Fe2+, permeabilitas air, sifat mekanik., Edible film from carrageenan is a thin layer made of food grade materials. Application of edible coating films could increase food product shelflife and protect food from microorganisms. The addition of cellulose, glycerol, nanocarbon, and crosslinker Fe2+ aims to improve the mechanical properties and permeability. Nanocarbon on edible film will flouresence when exposed to UV at a wavelength of 366 nm. The added nanocarbonwere 0.5, 1, 1.5, and 2% w/v. Tensile strength and permeability increased with increasing concentration of nanocarbon. The added cross-linker was 1.5%, 3%, and 5% w/v with the optimum value of tensile strength at 5%. The presence of carrageenan in this film was showed by Fourier transform infra-red in wave number 1234.44 cm-1 which is the characteristic of functional group in carrageenan, namely sulfate esters. Keywords: carrageenan, crosslinker Fe2+, mechanical properties, nanocarbon, permeability.
Keyword: karaginan, nanokarbon, penaut silang Fe2+, permeabilitas air, sifat mekanik

Judul: Edible Film dari Perpaduan Karaginan, Selulosa Bakteri, dan Nanokarbon dengan Penaut Silang Asam Sitrat
Abstrak: Edible film is a film made of food grade materials. The film has mechanical properties and can act as a barrier so that it can prolong the shelf life of food products. Carrageenan is a base material of film derived from seaweed (Eucheuma cottonii). Addition of glycerol, bacterial cellulose, nanocarbons, and citric acid were used as compatibilizers to improve the mechanical properties of the carrageenan film. The optimum composition of edible film composed of glycerol, bacterial cellulose, nanocarbon 1.5%, and citric acid 10% increased tensile strength up to 160% and decrease of water vapor permeability up to 42% as compared to the carrageenan film. Tensile strength and water vapor permeability values met the standard for edible film as food packaging. The result of infrared spectrum showed the formation of the new functional groups on 1717 cm-1 that caused by the addition of citric acid crosslinker. Luminescence of nanocarbon can be detected using ultraviolet light at wavelength of 366 nm with the presence of blue color
Keyword: Bogor Agricultural University (IPB), water vapor permeability, nanocarbon, mechanical properties, citric acid crosslinker, carrageenan

Judul: Dynamical System of Hepatitis B in Three Groups with Vaccination
Abstrak: The aim of this study is to modify the hepatitis B transmission model in three age groups involving vaccination from the model conducted by Zhoe and Zhang.The method used is to analyze the stability of the fixed point and its basic reproduction number (R_0). Performed stability analysis and numerical simulation to see population dynamics. Next, a sensitivity analysis of the parameters was carried out to see its effect on R_0. From the analysis obtained two fixed points, namely non-endemic and endemic fixed points. Non-endemic fixed points are locally asymptotically stable if R_0 <1 Meanwhile, the endemic fixed point is locally asymptotically stable if R_0 > 1. Hepatitis vaccination affects the number of susceptible population, because the more successful the vaccination, the smaller the number of susceptible populations so that the smaller the population will be infected.
Keyword: Dynamic, Hepatitis B, Vaccine, Mathematical model