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: Study of Biphasic Calcium Phosphate Ceramics and HA-Chitosan Composite Implanted into Sheep’s Bone
Abstrak: Biphasic Calcium Phosphate (BCP) biomaterials are recognized as biodegradable, bioresorbable, and osteoconductive material and, therefore, it is suitable for filling bone defects to aid regeneration process of new bone tissue. This study aimed to synthesize BCP ceramics by precipitation method and observe bone growth using BCP ceramics and HA-Chitosan composite implanted into sheep’s bone. BCP ceramics was prepared by precipitation of Na2HPO4.2H2O which was dropped by CaCl2.2H2O at temperature 700C with various molar ratios and various volume of solution. Molar ratio of Ca and P was variated approximately 0.2M:0.2M and 0.334M:0.2M while various volume of solution was 50 ml and 100 ml. BCP ceramics was formed which was indicated by mass of precipitate and the result showed that sample with greater molarity of Ca was resulting in bigger mass precipitate. It showed that higher molarity of Ca/P tends to be more mass precipitate. The X-Ray Diffraction results showed that BCP 100 ml with molar ratio Ca/P about 0.334M:0.2M had the expected characteristics of implant material for in vivo experiment into sheep’s bone. Moreover, it showed the consistency of sample which indicates that it was a reproducible biomaterial. This result was also supported by Fourier Transform Infrared (FTIR) and Scanning Electron Microscopy (SEM) characterization. In vivo study of BCP ceramics and HA-Chitosan composite showed that bone recovery without bone graft (control) was more complete than that with BCP and HA-Chitosan bone grafts. Based on pathological evaluation, the results indicated that BCP ceramics was biodegradable and bioresorbable but less osteoconductive. In the contrary, HA-chitosan composite was not biodegradable and bioresorbable but more osteoconductive. Moreover, BCP bone graft was more readily resorbed by the body than HAChitosan. Resorption of HA-Chitosan bone graft was very slow but new tissue growth was faster than that of BCP bone graft. In contrary, resorption of BCP bone graft was very fast but new tissue growth was very slow.
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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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