Judul: Sintesis Hidroksiapatit Berpori Berbasis Kalsium dari Cangkang Telur dan Porogen Lilin dari Sarang Lebah
Abstrak: Kalsium fosfat merupakan senyawa organik yang banyak digunakan dalam aplikasi medis. Jenis kalsium fosfat yang sering dipakai adalah hidroksiapatit (HAp) dan trikalsium fosfat (β -TKF). Sintesis Hidroksiapatit berpori ini dilakukan dengan metode sol - gel. Sintesis HAp berpori dibuat dari CaO, H3PO4, dan lilin lebah. Kalsium oksida (CaO) bersumber dari cangkang telur ayam yang telah dikalsinasi pada suhu 1000oC selama 5 jam. Pengunaan lilin lebah pada proses menghasilkan HAp berpori. Hasil karakterisasi XRD pada sampel menunjukkan hadirnya puncak milik HAp, β – TKF dan AKB. Terbentuknya HAp diperkuat juga dengan hasil karakterisasi spektroskopi FTIR ditandai dengan adanya gugus fosfat (PO4 3-), hidroksil (OH-), dan karbonat (CO3 2), selain itu terdapat juga gugus (C-H), (C=O) dan (C=C) yang menandakan masih adanya lilin yang tersisa pada sampel. Pada karakterisasi SEM juga menunjukkan terbentuknya kalsium fosfat yang ditandai dengan bentuk morfologi sampel yang terdiri dari butiranbutiran yang membentuk pori dengan ukuran pori makro diantara 1,3 μm sampai 2,5 μm.
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Judul: Sintesis dan Karakterisasi Hidroksiapatit Berpori dari Cangkang Kerang Darah (Anadara granosa Linn.) dengan Porogen Lilin Lebah
Abstrak: Calcium phosphate compound is ceramic material that is used as good biomaterial for bones because of its bioactive and good biocompatibility which the composition is same as pure bone. The most stable calcium phosphate compound is hydroxyapatite (HAp) (Ca10(PO4)6OH2). But HAp has low dissolving level, thus porous HAp was made. HAp was synthesized by sol gel methods with main calcium material was provided by Cockle (A. granosa ) and as the porous agent was used beeswax dissolved by ethanol 96%. This research was done by 5 difference concentrations of beeswax, i.e. 10%, 20%, 30%, 40%, and 50%. Synthesis result was analyzed with X-ray diffractometer, scanning electron microscopy, and Fourier transform infrared. The result from X-ray diffractometer analysis showed the best porous HAp in this research used 30% beeswax as porous agent. Scanning microscopy electron analysis result showed big porous formed by using 50% beeswax with average macro porous size was about 1,74 μm and average micro porous size was about 0,245 μm . Calcium phosphate compound was sintered on the temperature 900o C for 5 hours.
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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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