Judul: Aplikasi Poli(asam laktat) sebagai Mikrosfer Pengungkung Obat Selekoksib
Abstrak: Mikrosfer polimer biodegradabel, poli(asam laktat) (PLA) berisi selekoksib dibuat dengan metode penguapan pelarut dalam air. Mikrosfer yang dihasilkan dari metode ini homogen dan selekoksib terdistribusi di dalam matriks polimer. Parameter yang diamati adalah ukuran mikrosfer, efisiensi pengungkungan dan lepasan obat selekoksib secara in vitro. Pengamatan morfologi mikrosfer menggunakan scan electron microscope dan kristalinitasnya dengan XRD. Mikrosfer berisi obat diinkubasi dalam bufer fosfat + 2% Tween-80 pH 7.4, diperoleh lepasan awal yang meletus pada dua jam pertama diikuti dengan lepasan yang tetap sampai waktu inkubasi 24 jam. Hasil penelitian ini memperlihatkan ada pengaruh ukuran mikrosfer berisi obat selekoksib pada lepasan awal dari matriks polimer. Obat yang lepas dari mikrosfer dengan kandungan obat yang rendah (1% w/w) dipengaruhi oleh ukuran partikel. Naiknya kandungan obat dalam mkirosfer mulai 1% b/b sampai 5% b/b secara nyata obat lebih cepat lepas dari mikrosfer. Kata kunci: poli(asam laktat), mikrosfer, selekoksib, metode penguapan pelarut.
Keyword: 

Judul: Optimasi pembuatan mikrosfer polipaduan poliasamlaktat dengan polikaprolakton
Abstrak: Mikrosfer dapat digunakan sebagai sistem pembawa obat. Mikrosfer dibuat dari polipaduan antara poli(asam laktat) (PLA) dan polikaprolakton (PCL) dengan nisbah 9:1. Mikrosfer dibuat dengan metode emulsifikasi: PLA dan PCL dilarutkan dalam pelarut atsiri (diklorometana) lalu diemulsikan dan didispersikan ke dalam pelarut lain (air) sehingga terbentuk mikrosfer.Ukuran dan keseragaman mikrosfer dipengaruhi oleh kecepatan putar dan waktu emulsifikasi. Poli(vinil alkohol) (PVA) digunakan sebagai pengemulsi pada pembuatan mikrosfer polipaduan (PLA dengan PCL). Besarnya konsentrasi PVA yang ditambahkan memengaruhi stabilitas emulsi tersebut sehingga memengaruhi keseragaman ukuran mikrosfer yang didapatkan. Penggunaaan waktu emulsi 90 menit dan kecepatan putar 900 rpm meningkatkan keseragaman dan ukuran mikrosfer yang dihasilkan semakin kecil. Mikrosfer yang dihasilkan seluruhnya berukuran kurang dari 50 μm. PVA 2,50% mampu menghasilkan mikrosfer berukuran kurang dari 1 μm dengan persentase terbanyak, yakni sebesar 44,10% dan 55,90% sisanya berukuran 24-39 μm. Hal ini menunjukkan bahwa konsentrasi PVA 2,50% tidak hanya menghasilkan mikrosfer yang berukuran kecil, tetapi juga relatif seragam.
Keyword: 

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: