Judul: Profil Kimia Fraksi Aktif Antioksidan Dari Ekstrak Metanol Daun Pohon Penghasil Gaharu Aquilaria Microcarpa Hasil Inokulasi.
Abstrak: Aquilaria microcarpa merupakan salah satu pohon penghasil gaharu yang digunakan secara luas dalam produksi minyak atsiri. Tujuan penelitian ini adalah untuk mengidentifikasi komponen kimia fraksi aktif antioksidan dari ekstrak metanol daun pohon A. microcarpa hasil inokulasi. Percobaan dilakukan dengan mengekstraksi daun menggunakan pelarut metanol, lalu ekstrak kasar tersebut difraksionasi dengan teknik kromatografi kolom gradien menggunakan 4 pelarut yang berbeda polaritasnya. Fraksionasi dengan kolom silika gel menghasilkan 4 fraksi, yaitu fraksi diklorometana, diklorometana-metanol 1:1, metanol, dan metanol-air 1:1. Uji aktivitas antioksidan setiap fraksi menunjukkan bahwa fraksi metanol memiliki aktivitas tertinggi dalam penghambatan radikal 2,2-difenil-1- pikrilhidrazil (DPPH) dengan nilai IC50 25.89 μg/mL. Kromatogram gas-spektrum massa fraksi tersebut menunjukkan keberadaan senyawa fenolik, yaitu 5- nitropirimidina-2,4-diol (0.22%) dan amina sekunder aromatik, yaitu asam N-(3,5- dinitro-2-piridinil)aspartat (0.10%) yang diduga berperan sebagai senyawa antioksidan. Kapasitas antioksidan yang baik ini menunjukkan potensi daun A. microcarpa sebagai sumber obat yang berguna.
Keyword: amina sekunder aromatik, antioksidan, daun, fenolik, gaharu

Judul: Fraksionasi Ekstrak Kemedangan Gaharu Aquilaria microcarpa Hasil Inokulasi Berpotensi Antioksidan
Abstrak: Aquilaria microcarpa is an agarwood producing tree which is potential as an antioxidant resource. The objectives of this research were to determine the most active antioxidant fraction in the inoculated kemedangan A. microcarpa agarwood species and to characterize the functional groups contained in the fraction. The antioxidant activity analysis of ethyl acetate and methanol extracs showed the 50% inhibition concentration (IC50) value of 239 and 185 μg/mL, respectively. Methanol extract contained flavonoid, steroid, alkaloid, and phenolic compounds. The methanol extract was further fractionated using column chromatography with gradient elution system that yielded 12 fractions. According to the analysis, the fraction eluted with dichloromethane-ethyl acetate (9:1) was obtained as the most active fraction as antioxidant activity of 165 μg/mL IC50 value. The infrared spectrum of this fraction showed the presence of phenolic functional group that expected responsible for the antioxidant activity, with absorption bands of OH stretch at 3306 cm-1, CO stretch at 1246 cm-1, and aromatic C=C stretch at 1462 and 1597 cm-1.
Keyword: infrared spectra, IC50, fractionation, Aquilaria microcarpa, Bogor Agricultural University (IPB)

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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