Judul: Optimasi dan Evaluasi Mikrokapsul Ibuprofen Tersalut Polipaduan Poliasamlaktat−Lilin Lebah
Abstrak: Microencapsulation is a technique to encapsulate active ingredients by coating materials so called microcapsules. Microencapsulation of drugs in a polymeric matrix can control the release of drugs. In this experiment, microencapsulation of ibuprofen was done by emulsion-solvent evaporation methods. Coating materials used were polyblend of poly(lactic acid) (PLA) and beeswax due to its biodegradable and biocompatible properties. Gelatin was used as an emulsifier. The microencapsulation was carried out in various polyblend compositions of PLA:beeswax (6:4, 7:3, 8:2, and 9:1) and concentrations of emulsifier (1%, 1.5%, and 2%). The encapsulation efficiency of ibuprofen was higher than 80% in microcapsule with ratio of polyblend (PLA:beeswax) 9:1. The concentration of emulsifier is not significantly affected by encapsulation efficiency. Percent release of ibuprofen is directly proportional to the encapsulation efficiency. Kinetics of ibuprofen release followed Korsmeyer- Peppas kinetic model with mechanism of drug release based on super case-II transport. The microcapsule particle size ranged from 30 to 180 μm with homogeneous dispersion of the core within the polymeric matrix.
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Judul: Pelepasan Ibuprofen dari Mikrokapsul Tersalut Paduan Lilin Lebah dan Poli(asam laktat) Secara In Vitro
Abstrak: Ibuprofen as an anti-inflammatory drug has a short elimination rate which can causes gastric irritation. Microencapsulation technique can be used to overcome these problems and provide a better therapeutic efficacy through controlled drug release mechanism. In this research, microencapsulation of ibuprofen carried out by blending process and emulsion-solvent evaporation method. Ibuprofen was coated by blend beeswax and poly(lactic acid) (PLA) with various compositions (9:1, 8:2, 7:3, and 6:4) and concentration of gelatin (1%, 1.5%, and 2%) as an emulsifier. Efficiency of encapsulation performed in simulated intestinal medium pH 7.2. The highest value of ibuprofen encapsulation efficiencies was equal to 84.21% had been produced by microcapsules with ratio bees wax:PLA 6:4 and concentration of gelatin 2%. Release test of ibuprofen was performed by beeswax:PLA blend with ratio 8:2 and 6:4 produces the highest average percentage release about 15.31% and 19.25% at minute 225 in the same medium. The release pattern of ibuprofen had followed zero order kinetics model explaining that concentration of ibuprofen released relative constant for each release time. Observation of surface morphology of microcapsules using a scanning electron microscop (SEM) showed subtle bulges irregularly shaped scattered on its surface.
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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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