Judul: Synthesis and Characterization of Fluorapatite-Copper(II) Oxide with Sol-Gel Method as an Antibacterial Biomaterial
Abstrak: Fluorapatit (FAp) merupakan salah satu material kalsium fosfat yang berpotensi sebagai material antibakteri untuk pelapis implan gigi. Penelitian ini bertujuan menyintesis FAp pada tiga suhu pemasiran (600, 800, dan 1000 °C), tembaga(II) oksida (CuO), dan fluorapatit-tembaga(II) oksida (FAp-CuO) dengan metode sol-gel, serta menguji sifat antibakteri produk sintesis. Sintesis FAp melalui metode sol-gel telah berhasil dilakukan dan produk terbaik diperoleh pada suhu pemasiran 1000 °C (FAp 1000) berdasarkan nilai kristalinitasnya sebesar 90%. Hasil pencirian menggunakan difraktometer sinar-X (XRD), spektrometer inframerah transformasi Fourier, dan mikroskop elektron payaran-spektroskopi dispersif energi mengonfirmasi bahwa FAp 1000 merupakan fase dominan dengan nilai nisbah Ca/P dan P/F berturut-turut sebesar 1,84 dan 4,67. Produk CuO yang diperoleh juga merupakan fase dominan berdasarkan pola XRD. Penggantian ion Ca2+ oleh ion Cu2+ pada FAp-CuO terbukti mampu menurunkan nilai rerata ukuran kristal, kristalinitas, dan nisbah Ca/P. Tiga sampel uji (FAp, CuO, dan FAp-CuO) memiliki sifat antibakteri yang lemah terhadap Staphylococcus aureus dan Escherichia coli dengan rerata diameter zona hambat terbesar pada FAp-CuO, berturut-turut 0,243 dan 1,397 mm., Fluorapatite (FAp) is one of the calcium phosphate compounds that can be used as an antibacterial material for covering dental implants. This study aims to synthesize FAp at three sintering temperatures (600, 800, and 1000 °C), copper(II) oxide (CuO), and fluorapatite-copper(II) oxide (FAp-CuO) by sol-gel method, as well as test the antibacterial properties of synthetic products. Synthesis of FAp via the sol-gel process has been successfully carried out, and the best product is obtained at a sintering temperature of 1000 °C (FAp 1000) based on its crystallinity value of 90%. The characterization results using an X-ray diffractometer (XRD), Fourier-transform infrared spectrometer, and scanning electron microscope-energy dispersive spectroscopy confirmed that FAp 1000 was the dominant phase with Ca/P and P/F ratio values of 1,84 and 4,67; respectively. The CuO product formed is also the dominating phase according to the XRD pattern. Substituting Ca2+ ions with Cu2+ ions in FAp-CuO reduced the average crystal size, crystallinity, and Ca/P ratio. Three test samples (FAp, CuO, and FAp-CuO) had weak antibacterial properties against Staphylococcus aureus and Escherichia coli, with the largest average inhibitory zone diameter in FAp-CuO; 0,243 and 1,397 mm; respectively.
Keyword: antibakteri, fluorapatit-tembaga(II) oksida, pemasiran, sol-gel

Judul: Synthesis and Characterization of Fluorapatite with pH Variations Based on Rice Fields Snail Shells Using the Precipitation Method
Abstrak: Kerusakan pada gigi biasanya membutuhkan pengganti berupa gigi buatan, yaitu implan gigi. Salah satu bahan utama pembuatan implan gigi adalah fluorapatit (FAp) yang dapat berasal dari limbah cangkang keong sawah sebagai prekursor berupa kalsium hidroksida pada sintesis FAp. Penelitian ini bertujuan menyintesis dan mengkarakterisasi FAp berbasis cangkang keong sawah dengan metode presipitasi menggunakan variasi pH. Metode penelitian ini dilakukan melalui tiga tahap, yaitu preparasi sampel cangkang keong sawah, sintesis FAp dengan tiga variasi pH berbeda (5, 7, dan 9) menggunakan metode presipitasi dan karakterisasi FAp dengan X-ray diffraction (XRD). Hasil karakterisasi terbaik dilanjutkan dengan fourier transform infrared (FTIR) dan scanning electron miroscope energy dispersive X-ray (SEM-EDX). Hasil penelitian menunjukkan bahwa dari tiga variasi pH, maka FAp dengan pH 9 memiliki hasil yang terbaik berdasarkan hasil XRD (kristalinitas, ukuran kristal, fase kristal) dan rendemen. FAp pH 9 terbukti memiliki gugus fungsi -OH, OH-F, dan -PO43- yang sesuai dengan analisis FTIR. FAp dengan pH 9 juga terbukti memiliki morfologi permukaan yang seperti gumpalan dan rasio molaritas Ca/P sebesar 3,59 dan P/F sebesar 5,83 dengan analisis SEM-EDX., Damage to the teeth usually requires replacement in the form of artificial teeth, namely dental implants. One of the main ingredients for making dental implants is fluorapatite (FAp) which can be derived from rice snail shell waste as a precursor in the form of calcium hydroxide in FAp synthesis. This study aims to synthesize and characterize FAp based on rice field snail shells with the precipitation method using variations in pH. This research method was carried out in three stages, namely preparation of rice snail shell samples, synthesis of FAp with three different pH variations (5, 7, and 9) using the precipitation method, and FAp characterization by X-ray diffraction (XRD). The best characterization results were followed by fourier transform infrared (FTIR) and scanning electron microscopy energy dispersive X-ray (SEM-EDX). The results showed that of the three variations of pH, FAp with pH 9 had the best results based on XRD results (crystallinity, crystal size, crystal phase) and yield. FAp pH 9 proved to have functional groups -OH, OH-F, and -PO43- which was by FTIR analysis. FAp with pH 9 was also shown to have a lump-like surface morphology and a Ca/P molarity ratio of 3,59 and P/F of 5,83 by SEM-EDX analysis.
Keyword: Dental Implant, Fluorapatite, Precipitation, Rice Fields Snail Shell

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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