Judul: Imobilisasi Parakuat pada Hidrogel Poli(Vinil Alkohol) (PVA)-Lignin dengan Teknik Iradiasi Gama
Abstrak: Imobilisasi pestisida merupakan salah satu teknik untuk mengungkung atau menjerat pestisida dalam matriks yang pelepasannya dalam media dapat dikendalikan. Hidrogel poli(vinil alkohol) (PVA)-lignin digunakan sebagai matriks untuk pelepasan parakuat. Tujuan penelitian ini adalah menyintesis dan mencirikan hidrogel PVA-lignin dengan ragam dosis iradiasi gama sebagai matriks pelepasan terkendali parakuat. Hidrogel disintesis dengan proses beku-leleh dan iradiasi gama. Campuran PVA-lignin yang mengandung parakuat berbagai konsentrasi (25, 50, dan 100 ppm) dibeku-lelehkan selama 3 siklus dan diiradiasi gama dengan 4 dosis (0, 5, 10, dan 15 kGy). Parakuat dapat diimobilisasi pada matriks PVA-lignin dengan cara in situ loading dan pelepasan parakuat diuji dalam air selama 10 hari serta diukur menggunakan spektrofotometer UV-Vis. Kemampuan pelepasan parakuat dari hidogel PVA-lignin dipengaruhi oleh dosis iradiasi gama. Semakin tinggi dosis iradiasi gama semakin rendah parakuat yang lepas. Dengan demikian, hidrogel PVA-lignin dosis 15 kGy dapat digunakan sebagai matriks pelepasan parakuat yang terkendali.
Keyword: imobilisasi, iradiasi gama, hidrogel, lignin, parakuat, PVA

Judul: Imobilisasi Imidakloprid pada Hidrogel Poli(Vinil Alkohol)- Lignin dari Lindi Hitam dengan Teknik Iradiasi Gama
Abstrak: Penggunaan insektisida oleh petani sering kali tidak menakar secara pasti dosis yang digunakannya sehingga menimbulkan residu pada lahan pertanian. Imobilisasi insektisida pada hidrogel poli(vinil alkohol)-lignin merupakan salah satu teknik untuk menanggulangi dampak tersebut. Penelitian ini bertujuan mengisolasi lignin dari lindi hitam, menyintesis hidrogel PVA-lignin, dan mencirikannya dengan ragam dosis iradiasi gama sebagai alternatif pelepasan terkendali imidakloprid. Hidrogel dibuat dengan proses beku-leleh dan dilanjutkan iradiasi gama. Campuran PVA-lignin yang mengandung imidakloprid berbagai konsentrasi (450, 600, dan 800 ppm) dibeku-lelehkan dan diiradiasi gama berbagai dosis (0, 5, 10, dan 15 kGy). Fraksi gel tertinggi didapatkan pada hidrogel tanpa iradiasi, yaitu 90%, sedangkan daya serap air tertinggi didapatkan pada hidrogel dengan dosis 5 kGy, yaitu sebesar 225% pada jam ke-24. Pelepasan imidakloprid terbaik diperoleh dari hidrogel dengan dosis 10 kGy.
Keyword: hidrogel, imidakloprid, iradiasi, lignin, poli(vinil alkohol)

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: