Judul: Pencirian Plastik Antioksidan Paduan Poli(asam laktat)-Lilin Lebah dengan Penambahan Pemlastis Polietilena Glikol
Abstrak: The use of conventional plastics for packaging food has caused environmental and health problems. Antioxidant plastic poly(lactic acid) (PLA) and beeswax blend with polyethylene glycol addition as plasticizer can be a potential alternative for preparing biodegradable plastic. PLA-beeswax blend plastics were produced from PLA and beeswax solution with various compositions, i.e. 40:60, 50:50, 60:40, 70:30, and 80:20 by weight with polyethylene glycol level of 0,005; 0,01; and 0,02 g. The analysis was performed to measure density, tensile strength, morphological, and functional groups. Tensile strength, elongation, and density increases with the increasing PLA constituents. Functional group analysis showed a physical interaction. Plastic morphological results showed a good homogenous properties. PLA-beeswax ratio of 80:20 with the composition of polyethylene glycol 0,01 g produced the best mechanical properties.
Keyword: 

Judul: Pembuatan dan Pencirian Polipaduan Poliasamlaktat-Lilin Lebah
Abstrak: Nondegradable plastic waste could cause an environment problem due to its difficulty in degradation. The development of biodegradable polylacticacid (PLA)-beeswax polyblend is necessary to give alternatives of nondegradable plastic. PLA-beeswax polyblend were produced by mixing PLA and beeswax solution with various compositions namely 40:60, 50:50, 60:40, 70:30, and 80:20 by weight. The polyblends were tested for their tensile strength, density, fourier transform infrared spectroscopy (FTIR), and scanning electron microscope (SEM). PLA-beeswax polyblends were white in color. Tensile strength, elongation, and density increases as increasing of PLA constituents. FTIR spectrum of polyblend PLA-beeswax 80:20 did not show any new functional groups, meaning that the film was merely a physical mixture. Structure of the polyblend film revealed a homogenous film.
Keyword: 

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.
Keyword: