Judul: Aktivitas Antioksidan dan Bioaktivitas Kombinasi Fraksi Polifenol Daun Syzygium polyanthum dengan Guazuma ulmifolia.
Abstrak: Senyawa polifenol dalam daun salam (Syzygium polyanthum (Wight.) Walp.) dan daun jati belanda (Guazuma ulmifolia Lam.) berkhasiat sebagai antioksidan alami dan berkorelasi positif dengan aktivitas antikanker yang menunjukkan adanya bioaktivitas. Penelitian ini bertujuan menentukan aktivitas antioksidan kombinasi fraksi polifenol daun salam (SLM) dengan jati belanda (JBL) dan potensi bioaktivitasnya. Tiga kombinasi komponen digunakan dalam penelitian ini, yaitu: SLM=JBL (A), SLM<JBL (B), SLM>JBL (C). Fraksi polifenol diperoleh melalui fraksinasi ekstrak kasar etanol dengan n-heksana dan kloroform. Aktivitas antioksidan ditentukan dengan metode 2,2-difenil-1-pikrilhidrazil (DPPH) pada λ 516 nm. Potensi bioaktivitas ditentukan dengan Brine Shrimp Lethality Test (BSLT) melalui analisis Probit. Semua kombinasi memiliki aktivitas antioksidan sangat kuat (IC50 ≤ 50 μg/mL) dengan nilai IC50 18.05 μg/mL (C), 24.61 μg/mL (A), dan 40.56 μg/mL (B). Peningkatan kekuatan antioksidan berbanding lurus dengan peningkatan jumlah salam dalam kombinasi. Semua kombinasi bersifat sitotoksik dan memiliki potensi bioaktivitas (LC50<1000 μg/mL) dengan rentang nilai LC50 antara 55.05-153.76 μg/mL.
Keyword: antioksidan, jati belanda, kombinasi, salam, sitotoksik

Judul: Aktivitas Antioksidan dan Sitotoksisitas Metabolit Sekunder Daun Salam (Syzygium polyanthum Wight.) dan Daun Jati Belanda (Guazuma ulmifolia Lamk.)
Abstrak: Secondary metabolites from salam (Syzygium polyanthum Wight.) and jati belanda (Guazuma ulmifolia Lamk.) leaves can potentially be optimized for the utilization of these leaves as antioxidants. This research aimed to compare antioxidant activity and cytotoxicity of crude extracts of flavonoid, tanin, and hydroquinone of both type of leaves. Total phenolic and flavonoid compound was measured trough colorimetry, then the antioxidant activity was measured using 1.1-diphenil-2-picrylhydrazyl (DPPH) method and cytotoxicity test use brine shrimp lethality test (BSLT). Total phenolic value of salam leaves (614.70 mg GAE/100 g dried leaves) was higher when compared to jati belanda leaves (566.824 mg GAE/100 g dried leaves). Similarly, total flavonoids of salam leaves (434.234 mg QE/100 g dried leaves) was higher when compared to jati belanda leaves (246.214 mg QE/100 g dried leaves). This value is supported by IC50 values with DPPH method and LC50 values with cytotoxicity test showed the lowest IC50 and LC50 is flavonoid extract of salam leaves (IC50 = 10.833 μg/mL and LC50 = 328.427 μg/mL). Flavonoid of Salam leaves is the secondary metabolites with the best antioxidant activity and bioactivity effect.
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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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