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 dengan Porogen Polivinil Alkohol dan Pati
Abstrak: Hydroxyapatite (HAp) is a material resembles to structure of the human hard tissue. This material can be used for bone implantation. The ideal HAp is that with porosity of 100-150 μm in size. The porous HAp is used as a medium for the formation of bone tissue that grows and can enhance bone regeneration. Therefore, the synthesis of porous Hap was performed byprecipitation-sonication using sea shells Protothaca as the source of calcium and H3PO4 as the source of phosphorous. HAp pore structure was formed by adding various concentrations of polyvinyl alcohol (PVA) and starch at 10%, 15%, and 20%. Phase analysis of samples was carried out by x-ray diffraction (XRD), and morphological analysis by scanning electron microscopy (SEM). XRD results showed that, overall, the samples contain HAp phase. In addition, there were other phases of HAp such as apatite carbonate type A and type B, CaO and CaCO3. Based on SEM analysis, the best pore size was established by the addition of 15% concentratiton of PVA and starch, with the size of 2.89 μm and 2.81 μm, respectively.
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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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