Judul: Conversion of Borate-Based Bioglass to Hydroxyapatite in Phosphate Solution and Mixed of Phosphate and Carbonate Solution
Abstrak: Bioaktivitas material dengan sel merupakan salah satu parameter utama biokompatibilitas material yang berperan dalam regenerasi jaringan tulang baru. Biomaterial dengan luas permukaan yang besar mampu meningkatkan adhesi sel yang berperan dalam inisiasi regenerasi jaringan baru. Salah satu modifikasi untuk meningkatkan bioaktivitas material adalah pembuatan material dalam bentuk mikrosfer. Dalam penelitian ini dilakukan fabrikasi mikrosfer hidroksiapatit melalui konversi mikrosfer bioglass dalam larutan fosfat serta larutan campuran fosfat dan karbonat. Mikrosfer bioglass diperoleh melalui metode flame spray spheroidization dengan bahan baku dasar partikel bioglass berukuran 63 μm – 200 μm. Citra SEM menunjukkan bahwa mikrosfer bioglass berhasil difabrikasi dengan ukuran rata-rata 76,84 μm. Konversi mikrosfer bioglass dilakukan dengan variasi waktu pengamatan selama 14 hari. Hasil pola difraksi sinar-X menunjukkan bahwa mikrosfer kalsium fosfat untuk kedua larutan terbentuk pada hari ke-7 dan terdapat fasa apatit karbonat (CHA) pada hasil uji konversi dalam larutan campuran fosfat dan karbonat. Citra SEM pada hasil konversi menunjukkan bahwa ukuran mikrosfer kalsium fosfat memiliki rentang yang sama dengan ukuran mikrosfer bioglass sebelum uji konversi yaitu sebesar 73,59 μm – 90,83 μm. Hasil EDX menginformasikan bahwa mikrosfer kalsium fosfat memiliki rasio Ca/P yang mendekati literatur., The bioactivity of the material with cells is one of the main parameters for the biocompatibility of the material that plays a role in the regeneration of new bone tissue. Biomaterials with a large surface area are able to increase cell adhesion which plays a role in the initiation of new tissue regeneration. One of the modifications to increase the bioactivity of the material is the manufacture of the material in the form of microspheres. In this study, the fabrication of hydroxyapatite microspheres was carried out by converting bioglass microspheres in phosphate solution and a mixed solution of phosphate and carbonate. Bioglass microspheres were obtained through the flame spray spheroidization method with the basic raw material of bioglass particles measuring 63 μm – 200 μm. The SEM image shows that the bioglass microspheres were successfully fabricated with an average size of 76.84 μm. The conversion of bioglass microspheres was carried out by varying the observation time for 14 days. The results of the X-ray diffraction pattern showed that calcium phosphate microspheres for both solutions were formed on day 7 and there was an apatite carbonate (CHA) phase in the conversion test results in a mixed solution of phosphate and carbonate. The SEM image on the conversion results shows that the size of the calcium phosphate microspheres has the same range as the size of the bioglass microspheres before the conversion test, which is 73.59 μm – 90.83 μm. The EDX results inform that calcium phosphate microspheres have a Ca/P ratio close to the literature.
Keyword: Bone Graft, Carbonate Apatite, Flame Spray Spheroidization, SEM-EDX, XRD

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: Thermal Characteristics and Dynamics of Tropical Cyclone over Western North Pacific Ocean: A Case Study of Typhoon Songda (Chedeng) 2011
Abstrak: The frequent occasion of Tropical Cyclone (TC) over Western North Pacific (WNP) Ocean lies from 10˚N to 26˚N and 121˚E to 170˚E. Sources of TC development come from warm ocean temperature where latent heat is released during condensation processes and subsequently concentrated in the boundary layer. Relative humidity at 850-700 hPa is responsible to produce the most intense storm. Meanwhile, weak vertical wind shear between 850-200 hPa is one of the dynamical factors that lead to the development of TC. Pressure level of 850-200 hPa is chosen to minimize the thermodynamic effect in the lower troposphere. Typhoon Songda (Chedeng in the Philippines) or TSC lasted from May 18th to 30th, 2011 and strengthened into powerful Super Typhoon stage between May 24th and 27th. Long curving track and the exhibition of all sequences of TC life cycle, TSC is then considered as an ideal case of TC. The objective of the study with case of TSC is to investigate the role of thermal characteristics and dynamics on TC intensity. The research is carried out by using Advanced Research of Weather Research and Forecasting model (WRF ARW model) version 3.3. Two domains are employed in the model. The first domain situate from 02˚N to 40˚N and 118˚E to 149˚E and cover spatial resolution () of 33.1 km. The second domain situate from 09˚N to 27˚N and 119˚E to 132˚E with of 11 km. Timestep of the model () is 120 seconds. The model is supported by the following physical parameterization, i.e., Yonsei University Scheme (YSU) in the boundary layer, Kain-Fritsch scheme (KF) in the cumulus, and WRF Single-Moment 3-class scheme in the microphysics. Initial meteorological condition prior to the formation of the cyclone is generated using WRF ARW standard-release model. Sensitivity of the model output is obtained from a selected single-parameter change scenarios, namely, 10 % to 20 % decrease and increase of wind shear initial data at 850-200 hPa, and by 10 % to 20 % decrease of relative humidity initial data at 850-700 hPa. The result showed that the negative correlations between wind shear and intensity are found in wind shear scenarios. Wind shears of 10 ms-1 which lead to strengthening of the wind intensity in the early period of Typhoon development are found in wind shear scenarios. The effect of wind shear changes on wind intensity is statistically significant in the 20 % wind shear scenarios. During mature stage, weak wind intensity occurred when wind shear increase as given in the WRF standard-release and the 20 % decreasing scenario. Different situation is found in the 20 % increasing scenario where wind shear tend to weak and lead to strong wind intensity at this stage. Meanwhile, the reduction of moisture supply at 850-700 hPa resulting from 20 % decreasing relative humidity play a major role in the weakening of wind intensity and reduces mechanical energy of the cycle process as much as 300 J kg-1.
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