Judul: Limbah Padatan Penyamakan Kulit Ikan sebagai Material Hierarchical Porous Nanocarbon untuk Aplikasi Supercapacitor
Abstrak: Kulit ikan sebagian besar mengandung kolagen yang dapat dimanfaatkan sebagai kulit tersamakan. Limbah pada proses penyamakan kulit ikan umumnya merupakan limbah cair dengan padatan terlarut yang merupakan sumber material karbon yang sangat besar. Keberagaman dan meningkatnya sifat kelistrikan melalui hierarchical porous nanocarbon menjadikan limbah padatan berpotensi dikembangkan sebagai material untuk aplikasi superkapasitor. Pirolisis suhu 900oC selama 2 jam, aktivasi kimia kalium hidroksida (KOH) 3,5 M dan nanomilling partikel menghasilkan hierarchical porous nanocarbon dengan struktur kristal grafit, luas permukaan 624 m2/g, volume pori 0,4562 cm3/g dan ukuran partikel 170 + 40 nm. Elektroda superkapasitor yang diperoleh memiliki karakteristik konduktivitas elektron 7746,81 + 282,74 S/m dan kapasitansi muatan 380 F/g.
Keyword: hierarchical porous nanocarbon, kulit ikan, penyamakan, superkapasitor

Judul: Pembuatan Nanokarbon dari Limbah Baterai untuk Aplikasi Elektroda pada Superkapasitor
Abstrak: Carbon material is waste battery electrodes for supercapacitors are high potentially, since it has a high surface area, good chemical stability, and high conductivity. These carbon-based electrodes are promising candidates for energy storage devices with high performance is supercapacitor. Supercapacitor which has great potential in the storage of electrical charge, so it can be used as of equivalent fuel oil for motor vehicles, but it also wastes the battery can be recycled, thus reducing the danger of environmental pollution and public. Carbon material waste converted into nano-size batteries using High Energy Milling (HEM), to find out in the form of nano size using Particle Size Analyzer (PSA) produced 148.54 nm particle size. Furthermore, carbon material is a mixed nano size Poly (vinylidene fluoride) Polytetra and 1-methyl-2-pyrrolidone, glued in stainless steel. Results of carbon morfology form characterized using Scanning Electron Microscopy (SEM), crystallinity characterization of structures using X-Ray Diffraction (XRD), with a conductivity value of 7374.00 S/m. This suggests that carbon is a semiconductor material. Results of capacitance value with potentiostat 179.40 F/g for scan rate 5 mV/s.
Keyword: PSA, potentiostat, Carbon waste batteries, HEM, supercapacitor electrodes

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