Judul: Aktivitas Antioksidan berbagai Fraksi Ekstrak Etil Asetat 4 Strain Fungi Endofit dari Gyrinops versteegii
Abstrak: Fungi endofit merupakan mikroorganisme yang diketahui dapat menghasilkan metabolit sekunder yang sama seperti inangnya. Pohon Gyrinops versteegii diketahui memiliki kandungan fenolik yang berfungsi sebagai antioksidan. Fungi endofit diharapkan menjadi alternatif sebagai sumber produksi metabolit sekunder. Penelitian ini bertujuan mendapatkan ekstrak teraktif antioksidan dari empat isolat fungi endofit pohon G. versteegii. Ekstrak etil asetat kasar difraksinasi menggunakan ekstraksi cair-cair dan diperoleh empat fraksi, yaitu fraksi n-heksana, fraksi klorofom, fraksi etil asetat, dan fraksi metanol. Hasil ekstak fraksinasi didapatkan isolat P3DS1(A) dengan fraksi etil asetat merupakan isolat dengan potensi antioksidan kuat dengan IC50 sebesar 53.28 μg/mL dengan total fenol sebesar 43.52 mg ekuivalen asam galat (EAG)/g sampel dan total flavonoid sebesar 350.16 mg ekuivalen kuersetin (EK)/g sampel. Ekstrak etil asetat kultur cair fungi endofit yang diisolasi dari jaringan daun G. versteegii merupakan ekstrak teraktif antioksidan.
Keyword: Antioksidan, endofit, Gyrinops versteegii, fenolik

Judul: Pencirian Metabolit Sekunder dan Aktivitas Antioksidan dari Kulit Buah Gyrinops versteegii
Abstrak: Gaharu merupakan komoditas hasil hutan bukan kayu yang bernilai ekonomis yang tinggi karena aplikasinya yang sangat luas antara lain sebagai bahan wewangian, minyak atsiri, dan pengobatan. Kulit buah Gyrinops versteegii diharapkan dapat sebagai sumber produksi metabolit sekunder, salah satunya senyawa fenolik. Penelitian ini bertujuan mencirikan metabolit sekunder pada buah G. versteegii serta menentukan aktivitas antioksidannya. Simplisia dimaserasi menggunakan pelarut etil asetat, menghasilkan ekstrak dengan rendemen 9.90 %. Selanjutnya ekstrak difraksionasi menggunakan kromatografi cair vakum, menghasilkan fraksi paling sederhana, yaitu fraksi 11. Berdasarkan uji fitokimia kualitatif, fraksi 11 diduga mengandung steroid, sedangkan ekstrak etil asetat mengandung fenol, flavonoid, dan steroid. Kemudian hasil analisis fraksi 11 dengan LC-MS menunjukkan bahwa fraksi tersebut memiliki bobot molekul 497 dengan dugaan rumus molekul C30H40O6 yang merupakan golongan steroid. Aktivitas antioksidan tertinggi terdapat pada ekstrak kasar. Aktivitas antioksidan pada ekstrak kasar lebih baik dibandingkan dengan beberapa fraksi. Ekstrak kasar memiliki nilai IC50 sebesar 291 μg/mL.
Keyword: antioksidan, Gyrinops versteegii, steroid

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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