Judul: Sintesis dan Karakterisasi Hidroksiapatit Berbasis Cangkang Kerang Mencos (Anadara maculosa)
Abstrak: The research about synthesis hydroxyapatite (HA) used a single drop method with a precursor of a cockle shells (Anadara maculosa) as a source of calcium and H3PO4 as a source of phospate. Process of synthesis HA was done using variations of stirring time which were 1 hour, 3 hours, 6 hours, and 12 hours. The analytical results of atomic absorption spectrophotometer (AAS) indicated that higher calcination temperature of cockle shells made higher calcium that was produced. Analysis of x-ray diffractometer (XRD) indicated that the calcination temperature of 800 °C it was formed the phase of CaCO3 and at temperature 900 °C and 1000 °C it was formed the phase of CaO. The CaCO3 used as a source produced a TCP phase, that was different from CaO that produced HA phase. The calcination temperature was the main factor in the creation process of HA, while the long stirring time did not influenced the phases significantly. The analytical results of fourier infrared spectroscopy (FTIR) showed a groups of CO32- that indicated as BCA (B-type carbonate apatite) in all variations of samples.
Keyword: stirring, single drop, hydroxyapatite, cockle shells

Judul: Pemanfaatan cangkang kerang darah dalam Sintesis Nanohidroksiapatit
Abstrak: Research on the synthesis and characterization of nanohydroxyapatite, by using the source of calcium from the shells of mussles blood has been conducted. This research used ultrasonic waves through ultrasonication and precipitation methods for the shyntesis. Nanohydroxyapatite obtained was based on two treatmens which were CaO powder ultrasonication and hydroxyapatite powder ultrasonication. Ultrasonication process aims to minimize the spread and average particel size by using cavitation effect of ultrasonic waves propagating in a liquid medium. Ultrasonication in this research was counducted in three variation of time which were 30, 60 and 120 minutes with three replications for each treatment. The results of XRD characterization showed that for HA from CaO ultrasonication, appeared other phases whice are TCP and OCP. The result of optimum time for ultrasonication was 60 minutes. This is because at the time of ultrasonication 30 and 120 minutes, the distribution and average particle size were very large.
Keyword: XRD, ultrasonication, PSA, 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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