Judul: Sintesis Komposit Hidroksiapatit/Kolagen Berpori dengan Metode Freeze Drying
Abstrak: erkembangan ilmu material meningkat pesat setiap tahunnya. Salah satu pemicu utamanya adalah kecelakaan yang mengakibatkan patah tulang. Upaya untuk mengatasi ini adalah penggunaan material sintetik. Pada penelitian ini dilakukan sintesis hidroksiapatit/kolagen berpori dengan metode freeze drying sebagai material untuk graftting tulang. Hidroksiapatit dan kolagen dicampurkan dalam keadaan netral dengan rasio perbandingan hidroksiapatit:kolagen 80:20, kemudian dilakukan freeze drying selama 10 jam, 12 jam dan 14 jam. Hasil yang berbentuk scaffold diperoleh dengan waktu freeze drying selama 10 jam. Pencirian menggunakan FTIR menghasilkan spektra absorbansi gugus-gugus penyusun senyawa HAp dan kolagen. Berdasarkan hasil karakterisasi menggunakan SEM, komposit HAp/kolagen memiliki struktur porositas yang cukup teratur dengan ukuran yang bervariasi mulai dari 100 μm hingga 250 μm. Hal ini menunjukkan bahwa ukuran pori-pori yang terbentuk memenuhi syarat scaffold untuk grafting tulang, dimana persyaratan minimum untuk ukuran pori dianggap ~100 µm karena ukuran sel, persyaratan migrasi dan transport sel.
Keyword: collagen, composite, freeze drying, hydroxyapatite, porous

Judul: Synthesis and Characterization of HA-CHA/Collagen/Alginate and HA-CHA/Collagen/PVA/Alginate Composite  Scaffolds
Abstrak: Metode pencangkokan tulang yang sudah dikenal saat ini diantaranya yaitu autograft, allograft, dan xenograft. Meskipun metode tersebut terbukti dapat memperbaiki suatu jaringan tulang yang rusak, namun metode ini masih memiliki banyak keterbatasan yang dapat menyebabkan terhambatnya proses pengobatan. Salah satu upaya untuk mengatasi keterbatasan tersebut yaitu dengan dikembangkannya bone graft sintetis (scaffold). Fokus penelitian ini yaitu menyintesis scaffold komposit HA-CHA/Kolagen/Alginat dan HA CHA/Kolagen/PVA/Alginat menggunakan metode freeze-drying. Scaffold dibuat dengan memvariasikan komposisi komponen anorganik (HA, CHA) dan komponen organik (polimer) dengan rasio perbandingan anorganik:organik yaitu 25:75, 50:50, 75:25 dan HA:CHA masing-masing 100:0, 75:25, 50:50, 25:75, 0:100. Hasil sintesis kemudian dikarakterisasi menggunakan SEM-EDX, FTIR, dan XRD. Hasil SEM menunjukkan scaffold komposit HA-CHA/Kolagen/Alginat memiliki struktur morfologi cukup teratur dan pori-pori yang terbentuk tampak jelas, sedangkan scaffold komposit HA-CHA/Kolagen/PVA/Alginat memiliki struktur morfologi yang tidak teratur dan pori-pori tampak halus. Hasil pengujian EDX menunjukkan sebagian besar scaffold tersusun atas unsur karbon (C), oksigen (O), kalsium (Ca), dan fosfor (P). Hasil uji FTIR menunjukkan adanya keidentikan senyawa yang dihasilkan dan tidak terbentuk gugus fungsi baru. Hasil analisis XRD menunjukkan semakin besar kandungan organik dalam sampel akan memperkecil ukuran kristalit dan derajat kristalinitas dari scaffold., The methods of bone grafting that are known today are autograft, allograft, and xenograft. Although these method is proven to repair damaged bone tissue, but these techniques still have many limitations that can lead to inhibition of the treatment process. These limitations can be overcome by using a synthetic bone graft (scaffold). The focus of this study is synthesizing HA-CHA/Collagen/Alginate and HA-CHA/Collagen/PVA/Alginat composite scaffold using freeze-drying methods. Scaffold made by varying the composition between inorganic components (HA, CHA) and organic components (polymers) with inorganic:organic ratio is 25:75, 50:50, 75:25 and HA:CHA respectively 100:0, 75:25, 50:50, 25:75, 0:100. The synthesis results are characterized by SEM-EDX, FTIR, and XRD. The SEM results showed that the HA-CHA/Collagen/Alginate composite scaffold has a fairly regular morphological structure and the pores formed are clearly visible, while the HA-CHA/Collagen/PVA/Alginate composite scaffold has an irregular morphological structure and the pores look smooth. The EDX results test showed that most scaffolds are composed of the elements carbon (C), oxygen (O), calcium (Ca), and phosphorus (P). The results of the FTIR test showed the compounds produced are identical and do not form a new functional group. The results of XRD analysis showed that the greater organic content in the sample will reduce the size of the crystalline and crystallinity of the scaffold.
Keyword: Bone graft, composite scaffold, freeze-drying, inorganic-organic

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.
Keyword: