Judul: Sintesis Scaffold Hidroksiapatit dari Cangkang Kerang Hijau dengan Matriks Natrium Alginat dan Selulosa Bakteri Nata de coco
Abstrak: Research has been conducted on the synthesis of HA scaffold using sodium alginate matrix with freeze drying method and bacterial cellulose matrix of nata de coco by using immersion method. Synthesis of HA was done with green mussel shells as a source of calcium and phosphate precursor of (NH4)2HPO4. The synthesis results were characterized by using XRD, FTIR, and SEM. XRD results showed that there are phases other than HA such as TCP, ACA and ACB with the degree of crystallinity was obtained above 80%. Spectrum of XRD of HA/cellulose composites showing the typical peaks of cellulose and the typical peak of HA. The results of FTIR test detected that the cluster contained in HA/alginate composite with ratio 70/30 are OH-, PO4 3-, and CO3 2- showed the presence of HA and OH-, COO-, C-O showing the presence of sodium alginate. SEM test results indicated that the pores are formed in HA/alginate composite evenly distributed across the surface with a pore size ranging 65-120 μm, whereas HA/bacterial cellulose composite, HA was decomposed covering the entire surface of bacterial cellulose.
Keyword: Na-alginate., HA scaffold, Bacterial cellulose, Green clam shells

Judul: Sintesis Hidroksiapatit Dan Scaffold Β-Trikalsium Fosfat Dari Cangkang Kerang Darah (Anadara Granosa) Dengan Matriks Alginat.
Abstrak: Sintesis hidroksiapatit (HA) dari cangkang kerang darah (Anadara granosa) telah berhasil dibuat dengan metode wise drop (presipitasi). Ukuran kristal HA berkisar 25.84 nm sampai dengan 47.98 nm. Fraksi volume diperoleh sebesar 87.9%. Parameter kisi HA memiliki struktur heksagonal dengan a = b = 9.432 Å dan c = 6.881 Å. Derajat kristalinitas diperoleh sebesar 85.1 %. Melalui proses presipitasi wise drop juga telah berhasil dibuat β-Trikalcium Phosphate (β-TCP) antara kalsium oksida dari cangkang kerang dan H3PO4 dengan jumlah fraksi volume berkisar 87.4%. Fasa lain yang teridentifikasi adalah β- calcium diphosphate 12.6%,. Ukuran rata-rata kristalin serbuk β-TCP berkisar antara 4.6 nm sampai 13.9 nm dengan derajat kristalinitas sebesar 88.2 %. Gugus fungsi yang terdapat dalam serbuk β-TCP adalah PO4 3- , P2O7 4-. Metode freeze-drying digunakan untuk mensintesis perancah β-TCP /alginat dengan ukuran pori yang ideal. Fasa dalam perancah β -TCP/alginat tetap terdiri dari fasa serbuk β -TCP pada gugus PO4 3- , P2O7 4- dan alginat yang dicirikan oleh gugus COO-. Penggunaan crosslink agent CaCl2 menyebabkan adanya substitusi Ca ke dalam Na pada gugus COO-. Setelah digabungkan menjadi komposit gugus fungsi yang terdeteksi merupakan gabungan antara gugus fungsi dalam serbuk β-TCP dan alginat yaitu PO4 3- , P2O7 4- , COO- , dan OH-. Hasil μ- CT scan dan SEM diketahui bahwa scaffold β -TCP /Alginat –TKA 82, TKA-73, dan TKA-64 masingmasing memiliki ukuran pori rata-rata sebesar 62.38 μm, 155.83 μm dan 132.89 μm dengan porositas sebesar 57.28%, 67.29%, dan 66.7%. Ukuran pori dari seluruh scaffold β -TCP /Alginat yang disintesis dalam penelitian ini tidak seragam dan sampel TKA-73 memiliki distribusi ukuran pori yang paling seragam dibandingkan lainnya.
Keyword: alginat, hidroksiapatit, kerang darah, scaffold β-trikalsium fosfat

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.
Keyword: