Judul: Sintesis Monolaurin Menggunakan Enzim Lipase Imobil Dengan Packed Bed Reaktor
Abstrak: Monoasilgliserol (MAG) adalah salah satu emulsifier yang banyak digunakan sebagai bahan tambahan pangan. MAG secara luas digunakan dalam produk bakeri, margarin, produk susu, dan confectionary karena sifat emulsifikasi, stabilisasi, dan conditioning. Salah satu jenis MAG, yaitu monolaurin, monogliserida dari asam laurat, merupakan salah satu produk turunan dari minyak, yang memiliki keistimewaan. Kegunaan monolaurin adalah sebagai bahan pengawet pangan dan sanitizer. Saat ini monolaurin sudah banyak digunakan dalam industri kosmetik, farmasi dan obat-obatan. Saat ini cara umum yang banyak digunakan industri untuk sintesis monolaurin adalah dengan bantuan katalis kimia (alkali). Namun metode ini memiliki beberapa kekurangan seperti jumlah produk yang dihasilkan rendah, produk berwarna gelap, serta diperlukannya suhu dan energi tinggi dalam prosesnya. Oleh karena itu dikembangkan metode esterifikasi dengan katalis enzim lipase yang dapat mengatasi kekurangan-kekurangan dari metode kimia. Melalui metode esterifikasi dengan katalis enzim, dihasilkan produk dengan kadar MAG mencapai lebih dari 80%. Penelitian ini mengkaji mengenai hubungan antara laju alir volumetrik dan waktu tinggal substrat pada packed bed reactor dengan yield MAG yang dihasilkan dari sintesis yang dikatalis oleh enzim lipase imobil Novozym 435. Hasil menunjukan waktu tinggal optimum untuk memperoleh produk dengan persentase monolaurin maksimum (89.47%) adalah 94 menit. Waktu tinggal optimum tersebut dapat diperoleh dengan mengatur laju alir volumetrik substrat sebesar 0.4272 mL/menit.
Keyword: monolaurin, Novozym 435, esterifikasi, packed bed reactor

Judul: Optimasi sintesis monolaurin menggunakan katalis enzim lipase imobil pada circulated packed bed reaktor
Abstrak: Monolaurin is a special food grade monogliceride, which has a function beside as emulsifier and food preservative, also has an ability to destroy Herpes and HIV-1 virus. It was reported that monolaurin had the greatest antimicrobial activity among monoglycerides. Novozyme® 435 catalyze the esterification of lauric acid and glycerol in organic solvent. The purpose of this research were : 1) to obtain optimum condition to synthesis monolaurin using Novozyme® 435; 2) to analyze the stability of Novozyme® Continuous circulated packed bed reactor had residence time of 23,57 minute, glycerol/ oil molar ratio of 5:1, solvent/substrate ratio of 8,8:1, and the process produced MAG up to 80%. Optimization of synthesis MAG obtained quadratic equation which was Y= - 61,700 + 6,088 x 435 in continuous system. Continuous Esterification was employed in circulated packed bed reactor. This research was using Response Surface Methods (RSM) as experimental design and temperature and time reaction were as variables. 1+3,259 x2 – 0,065 x12 + 0,017 x1x2 – 1,792 x22 with R2 = 0,5408, optimum temperature and time reaction of 46,92oC and 1,1 hour, respectively. The product yield was 81,09% and contained MAG of 83,15%. The product had acid value of 1,78±0,08 %, peroxide value of 0,49 ± 0,14 meq O2/kg MAG, free glycerol content of 0,26%, and melting point 53-53,5o C. The enzyme remain stable during 10 reaction cycles and up to 70% produced of MAG at each cycle
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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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