Judul: Exfoliated Graphene Synthesis from Corn Cobs (Zea  mays L.) Based on Hansen Solubility Parameters
Abstrak: Tongkol jagung merupakan limbah yang banyak dari berbagai industri pertanian dan juga dapat dijadikan bahan baku grafena karena memiliki kandungan karbon yang cukup tinggi. Tujuan dari penelitian ini menyintesis grafena dari tongkol jagung dengan pelarut aseton dan air secara eksfoliasi berbasis parameter kelarutan Hansen dan studi literatur karakterisasi grafena. Sebelum dikonversi menjadi grafena, tongkol dijadikan arang dengan metode karbonisasi. Rendemen arang jagung adalah 17%. Eksfoliasi sintesis grafena dengan beragam campuran aseton dan air berbasis parameter kelarutan Hansen memberikan rendemen terbaik, yaitu 5,1% dengan campuran pelarut 80:20., The wasted corn cobs have been widely used as feed ingredients, crafts, fuel, and can be used as raw material for graphene because it has sufficiently high carbon content. This study aims to synthesize graphene from corn cobs with various acetone and water mixtures by exfoliating based on Hansen's solubility parameters and literature study for graphene characterization. Before graphene preparation, the corn cobs were converted into charcoal using the carbonization method, giving a 17% yield. The exfoliation of graphene synthesis under various acetone:water mixtures based on the Hansen solubility parameters gives the best yield, i.e., 5.1% in the acetone;water of 80:20.
Keyword: corn cobs, carbon, exfoliation, Hansen solubility, graphene

Judul: Kajian Ekstraksi dan Hidrolisis Xylan dari Tongkol Jagung (Zea mays L.)
Abstrak: Tongkol jagung merupakan salah satu limbah padat yang dihasilkan dari industri pengolahan jagung. Selama ini, tongkoljagung banyak dimanfaatkan sebagai makanan ternak. Pemanfaatannya sebagai bahan baku industri belum banyak dilakukan. Ditinjau dari komposisi kimianya, tongkol jagung mengandung banyak fraksi serat (lignoselulosa) yang terdiri dari selulosa, hemiselulosa dan lignin. Xilan adalah komponen utama hemiselulosa. Tongkol jagung merupakan sumber xilan yang potensial (dengan kadar xilan sebesar 31,94%). Xilan mempunyai banyak kegunaan sebagai bahan baku industri, diantaranya dapat dirnanfaatkan menjadi xilosa melalui proses hidrolisis seeara asam maupun enzimatis.
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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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