Judul: Sintesis dan Aplikasi Fase Diam Kromatografi Kolom Berbasis Selulosa-g-AAm: Variasi Penaut-Silang
Abstrak: Ela merupakan bahan lignoselulosa yang masih mengandung pati. Pati dalam ela dihidrolisis dengan HCl 3% dan lignin dihilangkan dengan H2O2 1.5% pH 12. Selulosa ela dimodifikasi melalui metode pencangkokan-penautan-silang dengan menggunakan inisiator amonium persulfat, monomer akrilamida (AAm), dan penaut-silang N,N’-metilena bis-akrilamida yang divariasikan sebanyak 0.5, 1.0, dan 2.0 g. Terbentuknya kopolimer cangkok-taut-silang ditunjukkan dengan spektrum inframerah transformasi Fourier yang memperlihatkan semua pita serapan khas selulosa maupun AAm. Kopolimer selulosa-graft-akrilamida (selulosa-g-AAm) yang terbentuk diaplikasikan sebagai fase diam kromatografi kolom untuk memisahkan senyawa kurkuminoid dan komponen nonpolar, yang salah satunya adalah xantorizol, dari ekstrak temu lawak. Analisis kualitatif dengan kromatografi lapis tipis menunjukkan bahwa selulosa-g-AAm dengan penaut-silang 1.0 dan 2.0 g memiliki kemampuan pemisahan senyawa kurkuminoid yang lebih baik daripada selulosa-g-AAm dengan penaut-silang 0.5 g. Pemisahan komponen nonpolar ekstrak temu lawak pada seluruh kopolimer cenderung tidak jauh berbeda.
Keyword: starchy lignocellulosic material, grafting-crosslinking method, cellulose-graft-acrylamide, Qualitative analysis, Ela

Judul: Sintesis Fase Diam Selulosa-g-AAm dengan Berbagai Kadar Penaut-silang sebagai Media Separator Xantorizol dari Ekstrak Temu Lawak
Abstrak: Rice straw in Indonesia is abundant and its cellulose can be modified to alter its characteristic. One of modification is by grafting-cross-linking method. The products will have a molecular structure that can be applied in separation technology. This research consists of three stages. The first stage was cellulose isolation, followed by cellulose-g-acrylamide synthesis at various amount of cross-linker (0.1, 0.5, and 1.0 g), and the last stage was application of the products as stationary phase. The success of isolation process was indicated by 0.81% residual lignin and increasing of alpha cellulose to 31.22%. Grafting-cross-linking process was indicated by increase of N and decreases of water absorption capacity in line with the increase of cross-linker amount. Functional group analysis showed some the characteristic bands, especially in wave number of 1674 cm-1, showing C═O of amide. All products were then applied on the column chromatography as stationary phase for separating xanthorrhizol. Based on thin layer chromatography profile, xanthorrhizol was always found in hexane fraction. However, all of copolymer tend to show similar performances. All samples can be reused twice for separation process.
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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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