Judul: Sintesis Depresan Titik Tuang Minyak Bumi Berbasis Asam Lemak dan Glikol.
Abstrak: Pengendapan parafin pada pipa penyalur minyak bumi dapat menurunkan produktivitas minyak bumi sehingga perlu upaya untuk mengendalikan proses pengendapan parafin melalui penambahan depresan titik tuang (DTT). DTT ini disintesis melalui esterifikasi asam lemak dengan glikol menggunakan katalis H2SO4. Kinerja DTT diuji melalui dua cara penambahan asam lemak, yakni sebelum inklusi urea dan setelahnya, dua jenis glikol, yaitu dietilena glikol (DEG) dan polietilena glikol 400 (PEG 400), dan tiga DTT dalam minyak bumi, 0.05%, 0.1%, dan 0.5% b/b). Gugus fungsi yang dicirikan menggunakan spektrofotometer inframerah transformasi Fourier mengindikasikan keberadaan gugus fungsi karbonil ester, hilangnya gugus fungsi karbonil asam karboksilat, dan hilangnya gugus OH. Penurunan titik tuang tidak dipengaruhi oleh komposisi asam lemak, tetapi jenis glikol dan konsentrasi DTT. Penurunan titik tuang terbesar adalah 9 °C pada konsentrasi tertinggi diester asam lemak-DEG dan 6 °C pada konsentrasi tertinggi diester asam lemak-PEG.
Keyword: asam lemak, depresan titik tuang, glikol, minyak bumi

Judul: Depresan Titik Tuang Berbasis Polimer dan Ester Oktil Oleat.
Abstrak: Depresan titik tuang (DTT) dapat digunakan untuk menurunkan titik tuang minyak mentah. Pada penelitian ini, DTT disintesis melalui esterifikasi asam oleat dengan 1-oktanol dan kopolimerisasi ester oktil oleat yang dihasilkan dengan monomer asam akrilat, akrilamida, atau (2-dimetilamino)etil metakrilat, lalu diuji pengaruhnya pada titik tuang dan perilaku aliran minyak mentah. Campuran dengan pelarut xilena telah dapat menurunkan titik tuang minyak mentah yang tergolong fraksi berat dan penambahan aditif kopolimer ester dapat meningkatkan kemampuan tersebut. Kopolimer ester dengan asam akrilat, misalnya, mampu menurunkan titik tuang sebesar 9 oC pada konsentrasi 1% (b/b). Fungsi aditif dalam menurunkan titik tuang teramati dari nilai viskositas sesaat yang lebih rendah dibandingkan dengan blangko. Oleh karena itu, aditif ini berhasil menurunkan titik tuang dan pada suhu 54 oC masih menunjukkan perilaku aliran tipe pseudoplastik.
Keyword: depresan titik tuang, esterifikasi, kopolimerisasi, perilaku aliran

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