Judul: Sintesis dan Karakterisasi Hidroksiapatit Berpori dengan Porogen Kitosan
Abstrak: This research had been done the synthesis of porous hydroxyapatite (HA) by sol gel method. The precusor calcium using eggshells and H3PO4 as phosphate source. The ratio of HA-chitosan to synthesize porous HA are 90:10, 80:20, 70:30, 60:40, and 50:50 and variation of chitosan size are 0.26 μm and 625.45 μm. The phase and crystaline structure of sample characterized by X-Ray Diffractometer. The porous HA with variation of chitosan A and chitosan B showed the percentage of HA would be rised if researcher added more of chitosan compotition, except HA-chitosan A 80:20, HA-chitosan B 80:20 and 70:30 be decreased, but did effect not for chrystaline size. The functional groups of HA identified by Fourier Transform Infrared Spectroscopy. The functional groups of HA which detected by are OH-, PO43-, and CO32-. The morphological structure of sample analyzed by Scanning Electron Microscopy. The result of sampel HA had shown the porouses structure using chitosan as porogen however it was small about 0.29-0.46 μm with the form of porouses are small cyrcle and the ditribution of porouses are smooth.
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Judul: Sintesis Hidroksiapatit Berpori dari Cangkang Telur Ayam dan Porogen dari Kitosan
Abstrak: This research had been done the synthesis of porous hydroxyapatite (HA) by presipitasi method. The precusor calcium using come from eggshells and (NH4)2HPO4 as phosphate source. The ratio of HA-chitosan to synthesize porous HA are 90:10, 80:20, 70:30, 60:40, and 50:50 and variation of chitosan size are 0.26 μm and 625.45 μm. The phase and crystaline structure of sample characterized by X-Ray Diffractometer. For sample with chitosan size 100% HA phase obtained. The biggest size of chrystaline gotten of HA_X60 sample by 63,83 nm. The functional groups of HA identified by Fourier Transform Infrared Spectroscopy. The functional groups of HA which detected by are OH-, PO4 3-, and CO3 2-. The morphological structure of sample analyzed by Scanning Electron Microscopy. The result of sampel HA had shown the porouses structure with chitosan as porogen however its size is quite small. In the order of about 0.2 – 1.6 μm in the form of cyrcle and the ditribution of porouses is smooth. Variation of chitosan size as porogen is not significant and has no effect to the crystal size.
Keyword: presipitasi., porous, hydroxyapatite, eggshells, Chitosan

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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