Judul: Desain Tipe Obstacle pada Bubble Column Reactor untuk Produksi Biodiesel Secara Non-Katalitik
Abstrak: Biodiesel is produced through the transesterification reaction of methanol with vegetable oils such as soybean oil, rapeseed, palm, sunflower seeds or jatropha. Commonly, there are two methods used in producing biodiesel; a non-catalytic and catalytic. One of application of non-catalytic method of biodiesel production is the Superheated metanol vapor method (SMV)-Bubble Column. However, the reaction rate of this method is very low. The reaction rate of biodiesel production could be increased by adding a perforated plate (called obstacle) in the reactor, due to obstacle serves to enlarge the contact surface area between methanol vapor and oil. The design of obstacle structures is thought to affect the contact surface area between metanol vapor and oil. By using the Computational Fluid Dynamics (CFD), the several types of obstacle will be simulated. The analysis of the design of obstacles performed using Computational Fluid Dynamics (CFD) because the use of CFD in the design analysis can reduce costs and shorten the time of research. CFD can also clearly describe the shape and distribution of bubbles in the reactor, making it easier to analyze the performance of the obstacles created. The simulation result shows that obstacle A3 has higher contact surface area than other obstacles that is equal to 0.0257 m2. The verification of the simulation data has proven that the obstacle (A3) results a higher total production compared to obstacle that has lower contact surface area (obstacle DO7 with an average of 0.0200 m2 surface contact area). For 5 hours time of operation, the total biodiesel production using obstacle DO7 are 7.32 gram at the first production and 7.41 gram at the second production, while the total production of biodiesel by using A3 obstacle at the first and second production are 7.74 gram and 8.7 gram respectively
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Judul: Analisis Konfigurasi Lubang Obstacle Terhadap Laju Reaksi Pembentukan Biodiesel pada Bubble Column Reactor
Abstrak: One of the non catalytic biodiesel production method is the Superheated Methanol Vapor in the Bubble column reactor. However, the weakness of this method is the low of rate of biodiesel production. The rate of biodiesel production was influent by the surface area between the methanol vapor bubble and oil, while the surface area was affected by the distribution of bubble size which produced from the obstacle hole. The objective of the study was to determine the best configuration of obstacle hole in order to increase the rate of biodiesel production in the Bubble Column Reactor from three design of obstacles tested until obtained the highest result of non catalytic biodiesel production. The design of obstacles were TO(123), TO(100), and TO(68), perforate plate which are connected by steel axis, where the three scenarios given name TO(X) means Triple Obstacle and symbol (X) is total hole in obstacle. These scenarios design were analyzed by the simulation processed using iv Computational Fluid Dynamics method. The best design from the simulation result was TO(100). The result obtained based on the highest surface area as a result of CFD simulation which was 0.0205 m2 and proven within the experiment result obtained the highest rate of biodiesel production which was 0.0114 gram/minute.
Keyword: Superheated methanol vapor., Obstacle, Computational fluid dynamics, Bubble column reactor, Biodiesel

Judul: Phylogeography and Species Limits in the Papuan White Snake (Micropechis ikaheka) (Reptilia: Serpentes: Elapidae)
Abstrak: Papua white snake, Micropechis ikaheka, has been distingushed into two subspecies M.i. ikaheka and M.i. fasciatus. However, due to lack of data on their morphology, distribution and ecology, both subspecies often ignored in scintific discussions and refers only byas , Micropechis ikaheka. This study was designed to document the differences between M.i. ikaheka and M.i fasciatus by using scales characteristics and reproductive organ or hemipenes. The study also examine, zoogeography, habitat, diet and cannibalism of both subspecies to better understanding the the ecology of one of the most venomous snakes in the world. This study consists of three topics with method and also different in the size samples, respectively. The first study is the histology and microtopography of the skin were studied using paraffin method and Scanning Electron Microscope (SEM). The second is the hemipenis were examined by following Myers and Cadle (2003), and Zaher and Prudente (2003). The third is the abdominal surgery was carried out to document diet type and the investigate phenomenon of cannibalism in the snake. Specimens for this study came from the collection from Museum Zoologicum Bogoriense (MZB) and Universitas Negeri Papua’s Laboratory (LZU). The research result also indicated that the markers of skin and hemipenis described the same structure and microornamentation in all M. ikaheka groups being compared. Based specimens examined morphological descriptions do not s support the further differentiation in Micropechis. In short, two markers that used in this study could not sufficiently indicate the differences in the level of species and subspecies of M. ikaheka. The study, however, were able to delineate zoogeography and skin color patterns, which fall into four groups: M. i. ikaheka; M. i. fasciatus. M. i. ssp. “intermediate”; and M. i. ssp “black”. This study also revealed that color variations did not overlap in their geographic distribution. It is therefore, it suggested that environmental factors may contribute to the skin color variations. It also assumed that habitat discontinuous and biogeography factors may also cause the loss of the connection between the original populations (vicarians) or follow colonization events (dispersal). The examined of 22 stomach contents of M. ikaheka shows this species is carnivorous, and prey on vertebrates such as amphibians, fish, reptiles, and Mammals. These snakes are opportunistic predators since they prey on all that can be captured, but mainly reptiles (61.5%), followed by mammals and fish (both 15.4%), and amphibians (7.7%). Although categorized as terrestrial animal, the diet study showed that M. ikaheka snakes often go into the water to hunt for fish (the sample from Yapen island), including eel (the sample from Aru island). Based on prey items indentified, there is evidence that M. ikaheka is cannibal. At this time, there still no record on reason for cannibalism, but it is assumed that cannibalism was due to competition between populations and means to control population.
Keyword: geographic variation, white snake, papua