Judul: Hydroxyapatite Synthesized from Mussel Shell as Flame-retardant for Intumescent Coating
Abstrak: Hidroksiapatit (HAp) adalah material berbasis fosfor yang memiliki kemampuan meningkatkan ketahanan api pada intumescent coating. Limbah cangkang kerang digunakan sebagai prekursor kalsium dalam sintesis HAp. Penelitian bertujuan menentukan karakteristik material intumescent coating dari HAp disintesis dari cangkang kerang. HAp diproduksi dari bubuk cangkang kerang dengan NaH2PO4 melalui proses sintesis hidrotermal pada suhu 140o C selama 5, 9 dan 12 jam. Berdasarkan analisis dengan XRD dan FTIR, cangkang kerang berhasil disintesis menjadi HAp. Uji ketahanan api dilakukan menggunakan kayu balsa yang dilapisi epoksi dan HAp tersintesis (1:3) pada paparan api selama 10 detik dengan suhu mencapai 268o C. Penambahan HAp tersintesis mampu meningkatkan ketahanan terhadap api dari intumescent coating dengan kemampuan memadamkan api dan membentuk lapisan arang. HAp hasil sintesis selama 12 jam menunjukkan hasil terbaik dalam memadamkan api sesaat setelah dijauhkan dari sumber api.
Keyword: cangkang kerang, hidroksiapatit, lapisan tahan api

Judul: Fire Resistance Coating Berbahan Dasar Hidroksiapatit dari Tulang Ikan Tuna (Thunnus albacares)
Abstrak: Hidroksiapatit (HAp) merupakan senyawa anorganik yang tersusun atas fosfor yang memiliki kemampuan dalam meningkatkan sifat ketahanan api. Material ini didapat dari sintesis tulang ikan hasil samping pengolahan ikan tuna. Penelitian ini bertujuan membuat dan menentukan karakteristik fire resistance coating berbahan dasar hidroksiapatit dari tulang ikan. Keunggulan pembuatan HAp dari tulang ikan yaitu dapat langsung disintesis tanpa memerlukan penambahan unsur P. Serbuk HAp didapat melalui proses sintering dengan suhu 900°C selama 5 jam dan dilakukan formulasi lapisan tahan api. HAp memiliki rendemen 51,11 ± 0,08%, rata-rata ukuran partikel 5,675 μm, kristalinitas 62,45% dengan struktur senyawa heksagonal dan rasio Ca/P 2,21. Hasil analisis TGA-DSC dan FTIR menunjukkan bahwa hidroksiapatit berhasil disintesis dari tulang ikan tuna. Pengujian ketahanan api dilakukan pada kayu jabon merah yang dilapisi HAp dan epoksi dengan perbandingan 0:0, 0:1, 1:1, 2:1 dan 3:1 yang dibakar selama 10 detik pada suhu 300°C. Lapisan HAp:epoksi dengan perbandingan 3:1 memberikan hasil terbaik dalam memadamkan api dan memiliki zona pirolisis terendah., Hydroxyapatite (HAp) is an inorganic compound composed of phosphorus which has ability to increase fire resistance properties. This compound is obtained from the synthesis of fish bones in by-product of tuna fish processing. This study aims to create and determine the characteristics of fire resistance coating based on hydroxyapatite from fish bones. The advantage of making HAp from fish bones is that can be synthesized directly without addition of phosphorus. HAp powder was obtained through sintering process at 900 °C for 5 hours and a flame retardant layer was formulated. The yield obtained 51,11 ± 0,08%, an average particle size of 5,675 μm, a percentage of crystallinity 62,45% with a hexagonal structure, Ca/P ratio of 2,21. Results of TGA-DSC and FTIR analysis showed that HAp was successfully synthesized from tuna fish bones. The fire resistance test was carried out on jabon merah wood coated with HAp and epoxy in a ratio of 0:0, 0:1, 1:1, 2:1 and 3:1 which was burned for 10 seconds at 300 °C. The HAp:epoxy layer with a ratio of 3:1 gave the best results in fire extinguish and produced the lowest pyrolysis zone.
Keyword: fire resistance coating, fish bone, hydroxyapatite

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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