Judul: Sintesis 2'-Hidroksikalkon Dari Resasetofenon Dan Metil Galat Sebagai Zat Antara (–)-Robidanol
Abstrak: (–)-Robidanol adalah salah satu flavonoid kelas flavan-3-ol tetrahidroksi yang telah diisolasi dari beberapa spesies tumbuhan. Senyawa ini memiliki aktivitas sebagai pemutih kulit, antijerawat, dan antioksidan. Flavan-3-ol lazim disintesis dari senyawa asetofenon dan benzaldehida terhidroksilasi melalui zat antara 2'-hidroksikalkon. Dalam penelitian ini, 2'-hidroksikalkon yang menjadi zat antara untuk sintesis (‒)-robidanol disintesis melalui reaksi kondensasi Claisen-Schmidt dari resasetofenon dan galaldehida dengan menggunakan katalis NaH 60%. Galaldehida diperoleh melalui serangkaian reaksi konversi dari metil galat. Gugus –OH fenolik pada bahan awal dilindungi dengan gugus pelindung benzil. Rendemen total 2'-hidroksikalkon yang diperoleh adalah 21% dalam 4 tahap dari metil galat. Kondisi reaksi kondensasi masih perlu dioptimisasi untuk meningkatkan rendemen kalkon murni sebelum dilanjutkan ke tahap berikutnya untuk memperoleh senyawa target (‒)-robidanol.
Keyword: antijerawat, flavan-3-ol, flavonoid, pemutih kulit, (–)-robidanol

Judul: Dekarbonilasi dan Dihidroksilasi Asimetris pada Kalkon Robtein Terproteksi-Benzil dalam Rute Sintetik ke (–)-Robidanol
Abstrak: (–)-Robidanol adalah isolat flavan-3-ol dari kayu merbau yang memiliki bioaktivitas sebagai pemutih kulit, antijerawat, dan antioksidan. Dalam pekerjaan sebelumnya untuk menyintesis (–)-robidanol, kalkon robtein terproteksi-benzil telah berhasil didapatkan sebagai zat antara. Dalam penelitian ini, kalkon tersebut didekarbonilasi mengikuti prosedur reduksi Luche dengan natrium borohidrida dan serium(III) klorida sebagai katalis. Deoksokalkon kemudian dihidroksilasi mengikuti prosedur Sharpless untuk mendapatkan senyawa antara, (1S,2S)-3-[4- benziloksi-2-hidroksifenil]-1-[3,4,5-tris(benziloksi)fenil]-propana-1,2-diol. Gugus 2-hidroksi diproteksi sebagai eter tert-butildimetilsilil selama reaksi ini. Rendemen keseluruhan ialah 10% dari kalkon robtein terproteksi. Tahap reduksi Luche masih perlu dioptimasi. Beberapa produk samping terpantau dengan kromatografi lapis tipis, diduga berasal dari reduksi parsial keton ke alkohol dan siklisasi alkohol tersebut ke flav-3-ena, dan sulit dimurnikan. Oleh sebab itu, proteksi gugus fenol dilakukan langsung pada produk dekarbonilasi kasar. Siklisasi diol dengan prosedur Mitsunobu adalah tahap selanjutnya untuk memperoleh (+)-epirobidanol, epimer C-3 dari (–)-robidanol.
Keyword: epirobidanol, flavonoid, merbau, pemutih kulit, reduksi Luche

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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