Judul: Bioactivity examination for calcium phosphate-chitosan composites in simulated body fluid Pembimbing
Abstrak: Calcium phosphate-chitosan composites such of biomaterial that had biodegradable and bioactivity characteristics, therefore it potentially to make a biomaterial of bone substitution. This study aimed to synthesize calcium phosphate-chitosan composites and examine that composites had both of characteristics with in vitro evaluation by immersion in Simulated Body Fluid (SBF). Calcium phosphate was prepared by precipitation of Ca from eggshell which was dropped by ((NH4)2HPO4) at temperature 37oC. Molar ratio Ca and P was calculated approximately 0.3 M and 0.18 M for each volume 100 ml. Result of precipitation was precipitated 24 hours then was filtered. Precipitation results was dried at temperature 110oC for 5 hours then at 900oC for 5 hours to resulting hydroxyapatite (HAp) and at temperature 110oC for 5 hours to resulting carbonated apatite (AK). Calcium phosphate-chitosan composites was prepared by sonication method. Optimate composition of calcium phosphate-chitosan composites were 64% HAp, 16% AK, and 20% chitosan. Composition was sonicated for 3 hours untill homogen. Sonication results was dried in incubator at temperature 50ºC for 15 hours. In vitro by immersion in SBF was prepared by increasing consecutively KCl, NaCl, NaHCO3, MgSO4.7H2O, CaCl2, Tris+HCl, NaN3, and KH2PO4 then added aquabidest 100 ml. Composites was formed as a pellet then immersed in 50 ml SBF in petridish for 3 months and was observed for each week. Biodegradable characteristics results showed that there were alteration of weight-loss in composites. Bioactivity showed by X-Ray Diffraction (XRD), Fourrier Transform Infrared (FTIR), and Scanning Electron Microscophy (SEM). X-Ray Diffraction results showed that alteration phase mostly to HAp but there were fluctuative rate on crystallinity degree. FTIR spectra indicated that the longer the time of immersion, compositions for each chemical functions was decreased and it supported by SEM results that showed by the greater agglomerated particles and cavity in the longer time. Based on result, after in vitro evaluation by immersion in SBF indicated that calcium phosphate-chitosan composites had biodegradable and bioactivity characteristics it caused there were some interactions between composites and SBF.
Keyword: Composites, Calcv apatite, In vitro evaluation, Bogor Agricultural University

Judul: Synthesis of Apatite - Chitosan Composite Using Duck Eggshell and Chitosan with Temperature and pH Control
Abstrak: Composite of apatite-chitosan was prepared by using chitosan as polymer matrix. Calcium phosphate was prepared from CaO and (NH4)2HPO4, which the ratio Ca : P had to be 1.67. Chitosan is produced by deacetilase from biopolymer chitin. Duck eggshell (95% CaCO3) as starting material was converted to be calcium oxide (CaO) through calcinations with temperature 1000oC for 5 hours. In-situ and ex-situ methods were prepared from apatite and chitosan (dissolved with acetate acid 2%). Calcium phosphate prepared for bone implantation, but it is too fragile and brittle to be implant into the body. So addition of chitosan can decrease crystalinity and increase mechanic characteristic (tougher). Composite apatite-chitosan was resulted by fast precipitation. Fast precipitation was held in a breaker glass with nitrogen atmosphere, under controlled temperature at 37oC and pH 7, in order to increase amount of hydroxyapatite. Precipitation with CaO which was dropped by (NH4)2HPO4. Hydroxyapatite and chitosan were appearing at samples with in-situ and ex-situ methods which indicating by peak matching of XRD (closed lattice parameter, crystal size), overlapping at FTIR spectra and supporting by SEM picture (homogenous and agglomerated particle). However, it still needs further research to examine biocompatibility osteoconductive degree of sample by in-vivo and in-vitro test.
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Judul: Rantai Markov Pada Bilangan Biner
Abstrak: Ranlai Markov {Xn} yang didefinisikan pada ruang peluang (n, P, P) dilllana n = (O,I],dan 'Fadalah cr-lapangan Borel, lllelllpunyai ekspansi biner X n = 0, dl(n) din).. n = I, 2, ... Mengkonstruksi rantai Markov ini diawali dengan memilih sembarang bilangan ..Y o di (0,1], nyatakan bilangan Xo dalam ekspansi biner Xo =0, diD) diD) ... d~O) ... dimana { d~O) ,n = 1,2, ... } adalah barisan nol dan satu. Peubah acak XI ditentukan oleh .Xo dan asumsi berikut.
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