Judul: Kajian Pustaka Sintesis dan Karakterisasi Hidroksiapatit Berbagai Cangkang Kerang Dengan Metode Basah dan Kering
Abstrak: Hidroksiapatit merupakan biomaterial yang memiliki komposisi yang mirip seperti tulang dan gigi manusia serta banyak digunakan sebagai aplikasi biomedis. Hidroksiapatit dapat disintesis melalui dua metode, yaitu metode basah dan metode kering. Penelitian ini bertujuan mengkaji berbagai metode dalam menyintesis HAp yang berasal dari berbagai cangkang kerang sebagai prekursor kalsiumnya. Metode yang digunakan pada penelitian ini berupa kajian pustaka dengan mengumpulkan berbagai sumber pustaka kemudian dikaji sesuai dengan topik penelitian. Hasil sintesis HAp yang terbaik pada kajian pustaka ini terdapat pada cangkang kerang hijau dengan metode presipitasi. Sintesis HAp dari cangkang kerang hijau menghasilkan rasio Ca/P 1.67 dan kristalinitas yang tinggi serta memiliki morfologi berupa butiran yang seragam., Hydroxyapatite is a biomaterial that has a similar composition to human bones and teeth and is widely used as a biomedical application. Hydroxyapatite can be synthesized by two methods, namely wet method and dry method. The study aims to study various methods in the synthesis of HAp derived from various shell shells as precursors of calcium. The method used in this study is a library study by collecting various library sources and then examined according to the research topic. The best results of HAp synthesis in the study of this library are found on the shell of green shells by the precipitation method. The HAp synthesis of the green shell produces a Ca/P ratio of 1.67 and a high crystallinity and has a uniform morphology of particles.
Keyword: hidroksiapatit, kerang hijau, metode presipitasi

Judul: Sintesis dan Karakterisasi Hidroksiapatit dari Cangkang Kerang Ranga
Abstrak: Hidroksiapatit adalah material keramik yang digunakan sebagai biomaterial yang baik untuk tulang karena bersifat bioaktif. Dalam rangka meningkatkan sifat bioaktif tersebut maka dipilih bahan alami sebagai sumber prekursor kalsium, pada penelitian ini bahan yang digunakan sebagai sumber kalsiumnya adalah cangkang kerang ranga. Serbuk cangkang kerang yang digunakan diperoleh dari perairan Belitung. Sebelum digunakan, serbuk cangkang kerang diidentifikasi fase kalsiumnya dengan x-ray diffractometer dan atomic absorption spectrophotometer. Hasil analisis menunjukkan fase kalsium yang dimiliki oleh cangkang kerang adalah CaCO3 dengan kadar kalsium 79,68%. Sintesis hidroksiapatit dilakukan dengan metode presipitasi pada suhu 800C yaitu dengan meneteskan larutan H3PO4 pada larutan kalsium. Selanjutnya dilakukan proses pengeringan 1100C dan sintering pada suhu 9000C. Nisbah konsentrasi kalsium dan fosfat yang digunakan yaitu 1,67 dengan konsentasi kalsium 0,5 M dan 1 M. Hasil sintesis dikarakterisasi dengan X-ray diffractometer, UV-VIS Spektrometer, atomic absorption spectrophotometer, dan spektrofotometer fourier transform infrared. Dari hasil analisis, hidroksiapatit diperoleh dari sintesis dengan konsentrsi kalsium 0,5 M dan sintering pada suhu 9000C. Pada konsentrasi ini, jika hanya dikeringkan pada suhu 1100C hasilnya campuran hidroksiapatit dan apatit karbonat. Sintesis dengan konsentrasi kalsium 1,0 M menunjukan masih terdapat raw material pada sampel, sedangkan pada proses sintering dengan suhu kalsinasi 9000C hasil yang diperoleh adalah hidroksiapatit.
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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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