Judul: Sintesis Komposit Hidroksiapatit-MgO-Kitosan Berporogen yang Berpotensi sebagai Implan Antibakteri
Abstrak: Kerusakan tulang dan gigi yang terus meningkat di kalangan masyarakat memicu pengembangan riset sintesis biomaterial sebagai implan. Tujuan penelitian ini adalah menyintesis komposit hidroksiapatit-MgO-kitosan sebagai implan antibakteri. Hidroksiapatit (HAp) dapat disintesis menggunakan metode presipitasi dengan mencampurkan serbuk HAp berporogen pati singkong dengan MgO ke dalam larutan kitosan 3%. Hasil spektrum inframerah transformasi Fourier menunjukkan adanya gugus O−H, C−O, −PO43-, dan C−H. Hasil difraksi sinar-X memperlihatkan puncak difraksi dari HAp dan MgO. Tambahan pati singkong sebagai porogen dapat menambah ukuran pori dari HAp. Karakterisasi menggunakan mikroskop elektron payaran dari hasil studi literatur menunjukkan ukuran pori HAp sebesar 13.2−46.79 μm. Komposit HAp-MgO-CTS 3% berpotensi sebagai implan antibakteri. Pengujian antibakteri dilakukan terhadap Staphylococcus aureus dan Escherichia coli. Dari penelusuran literatur, aktivitas antibakteri komposit HAp-MgO-CTS 3% memperlihatkan zona hambat 2 mm terhadap S. aureus.
Keyword: antibakteri, hidroksiapatit, kitosan, MgO, pati singkong

Judul: Sintesis dan Pencirian Komposit Hidroksiapatit-MgOKitosan sebagai Implan Antibakteri
Abstrak: Hidroksiapatit dapat digunakan menjadi bahan implan untuk bidang ortopedi dan aplikasi medis gigi. Infeksi pascaoperasi dapat diatasi dengan pengembangan implan antibakteri. Komposit hidroksiapatit-MgO-kitosan (HAp-MgO-CTS) disintesis untuk mendapatkan implan antibakteri yang baik. Metode yang digunakan pada sintesis hidroksiapatit dari cangkang tutut ialah presipitasi basah. Jenis komposit yang dibuat dengan 3 ragam tambahan kitosan, yaitu 1%, 2%, 3% dengan metode pencampuran sederhana. Aktivitas antibakteri diuji dengan metode cawan agar pada bakteri Staphylococcus aureus dan Escherichia coli. Nisbah Ca/P yang diperoleh dari sintesis komposit ini 1.66 dan hasil spektrum transformasi Fourier inframerah menunjukkan adanya gugus O-H, C-O, -PO4 3-, C-H, dan MgO. Kristalinitas yang terbentuk yaitu 71.34% dengan puncak difraksi tertinggi pada sudut 2θ 31ο, 32ο dan 33ο. Aktivitas antibakteri hanya diperoleh pada komposit HAp-MgO-CTS 3% dengan zona hambat 2 mm terhadap Staphlyococcus aureus.
Keyword: antibakteri, hidroksiapatit (HAp), komposit HAp-MgO-CTS

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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