Judul: Pigmen Fikoeritrin dari Mikroalga Porphyridium cruentum Sebagai Fotosensitizer pada Sel Surya Tersensitisasi Dye
Abstrak: The availability of solar energy is limitless and it is one of the renewable energy, so the development must be conducted to supports National Energy Policy Program. Harvesting solar energy require a technology that able to transform directly from solar energy into electric energy. The technology is solar cell. Dye-sensitized solar cell provide choice for easier and cheaper energy compared to commercial solar cell. Organic dye obtained from plants, while the inorganic dye obtained from chemical elements or the result of the chemical reaction. One of organic dye that can be used is phycoerythrin. The methods that used in the process of making solar cells including ultrasonication and doctor blade. Treatment performed by immersion colloidal TiO2 in dyes for 3 days is the best treatment where it gains the effiency value of 0,475 % with the maximum voltage and current of 138,3 mV and 0,00275 mA. While the other immersion time, 1 and 2 days, get the efficiency value of 0,304 % and 0,209 %.
Keyword: Porphyridium cruentum, phycoerythrin, dye-sensitized solar cell

Judul: Aplikasi Pigmen Klorofil Sargassum Sp. pada Prototipe Sel Surya.
Abstrak: Energi matahari merupakan salah satu energi terbarui dan tersedia secara melimpah sehingga pemanfaatannya harus ditingkatkan. Pemanenan energi matahari diperlukan suatu teknologi yang dapat mengubah energi matahari menjadi energi listrik secara langsung. Teknologi tersebut adalah teknologi sel surya (solar cell). Dye-sensitized solar cells memberikan alternatif dalam hal penyediaan energi yang lebih mudah dan lebih murah dibandingkan dengan solar cell komersial yang saat ini dijual. Dye yang digunakan untuk pelapisan DSSC adalah dye organik yaitu klorofil. Penelitian ini bertujuan mengembangkan solar cell tersensitisasi dye menggunakan pigmen klorofil dari rumput laut (Sargassum sp.). Metode yang digunakan meliputi ekstraksi dan teknik doctor blade. Perlakuan dengan perendaman lapisan dalam dye klorofil selama 30 jam adalah perlakuan terbaik dengan nilai efisiensi 1,43% dengan tegangan dan arus maksimal 159,3 mV dan 0,009 mA. Perlakuan perendaman 5 jam, 15 jam, 45 jam dn 60 jam mendapatkan nilai efisiensi sebesar 0,51%, 0,92%, 0,76%, dan 0,62%. Penurunan absorbansi klorofil setelah dilakukan penyimpanan klorofil selama 7 hari.
Keyword: pigmen klorofil, Sargassum sp., sel surya tersetisisasi dye

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