Judul: Studi Habitat dan Perilaku Orang Utan (Pongo pygmaeus abelii) di Bohorok Taman Nasional Gunung Leuser.
Abstrak: Orang-utans are big primates living arboreally and solitarily. Their solitary characteristics, wich was found to be quite different from those of other primate species, have been one of the difficulty factors for discovering them in their dwelling places in forests. This in turn, have resulted in a limited number of orang-utans having systemtically been traced during the course of data. collection. The study was aimedd to explore the habitat, daily activities and population of orang-utans related to habitat condition of Bohorok Nastional Park located in Gunung Leuser, and was carried out in forest areas of Sungai Landak and Sungai Musam, from July 1991 until January 1992. Survey methods employed were both the descriptive and qualitative methods. Observations on habitat conditions have included forest structure, vegetation type and composition, preference of food types and home range. Observations on feeding behavior, movements, restings and defensive behaviour to human disturbances and predators within their home range have also been carried out. Vegetation analysis have been carried out by using multiple plot method, and 144 sample plots have been obtained from five longitudinal stripes in forest areas of Sungai Landak and Sungai Musam. ehowed that the dominant species was materialis) with INP of Vegetation analysis 'damar laut' (Shorea 20.06%, 'kayu minyak' (Dipterocarpus sp.) with INP of 19.5%, 'samak jambu (Ixonanthus icesandra) with INP of 15.60%, and 'kayu merah' (Eugenia sp.) with INP of 13.1%. Tree density was fourd to be relatively low, i.e.. only 216 trees/ha, with species variability index (Shannon Wiener Index) of 3.78 and uniformity index of 0.83. Species variability index was considered relatively high and consisted of various age levels of natural forests. Among the various species related to tree densities, the densities of those which served as principal food sources of orang-utans, have been found to be relatively low. Tree density of Ficus sp. for example, was only 0.90 trees/ha, rambung-rambung' (Vernonea arborea) 1.67 trees/ha, rengas' (Gluata rengas) only 0.69 trees/ha, 'baju barus' (Manglietia glauca) 0.83 trees/ha, 'banitan' (Polyanthia glauca) 0.83 trees/ha.
Keyword: Pongo pymaeus abelii

Judul: Karakteristik Pohon Tempat Bersarang Orangutan Sumatera (Pongo abelii Lesson, 1827) di Kawasan Hutan Batang Toru, Kabupaten Tapanuli Utara – Sumatera Utara
Abstrak: The decline of natural habitat of Sumatran Orangutan (Pongo abelii Lesson, 1827) and persecution causing it's population decline. Batang Toru Forest has an important value as a habitat of Sumatran Orangutan which is separated from it's main habitat in Leuser Ecosystem (Aceh). Orangutan is rare species and it has preferention of choosing the nest location and the species of nesting tree with spesific characteristics. The objective of this research is to discover the characteristics of Sumatran Orangutan's nesting tree in Batang Toru Forest. The research conducted at October 23th until December 22th 2008 in Research Station Yayasan Ekosistem Lestari – Sumatran Orangutan Conservation Program (YELSOCP) in the 12,75 km2 area of West Block of Batang Toru Forest, in North Tapanuli of North Sumatera. Equipment that used are girth measuring tape, 30 m measuring tape, 20 m rope, machete, compas, flagging tape, digital camera, camera trap, thermo-hygrometer, watch, and stationary. Primary data are vegetation structure and composition, temperature and humidity, water availability, and profil of nesting tree (species of tree, total height, diameter, crown width, and crown shape), nest height, nest position, and the existence of other animals. This primary data are colected by nest survey method and vegetation analysis. Secondary data are general condition of research site and bio-ecology of Sumatran Orangutan. During the research found 154 nesting trees, it’s content 20 tree species. 33,74% (52 trees) of it is Hoting (Lithocarpus spp.). The tree height of nesting tree is about 16-20 m (34%) with average tree height from all trees is 20,35 m and average nest height in 17,24 m. In such as low nest and tree height the Orangutan's nest is covered by the taller crown of other trees from rain and wind. Orangutan tend to build their nest at tree with diameter 10-19 cm and average diameter from all the trees is 23,71 cm. The crown width less than 11 m2 with average from all the trees 15,64 m2. Orangutan's nest near the river indicated that nest location preferention caused by the location near the river is lower (the slope area). In the research location, potential competitor animal are Siamang (Symphalangus syndactilus), Gibbon (Hylobates agilis ungko), Pig-tailed monkey (Macaca nemestrina), Binturong (Arctictis binturong), squirrel (Callosciurus notatus) and Hornbill. The concultion of nesting tree characteristics are total height 16-20 m, diameter 10- 19 cm, crown width less then 11 m2, and ball shape crown. Hoting (Lithocarpus spp.) is tree species that qualify with that tree characteristics, for that reason Orangutan in Batang Toru Forest prefer to use this tree species than other tree. The location preferention is location which is covered from rain and wind.
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Judul: Hydroxyapatite-Chitosan Composite Coating on Stainless Steel 316 to Improve Corrosion Resistance
Abstrak: Metals that were used in bone implantation should have good corrosion resistance that were not easily corroded when implanted into the body. Metal corrosion resistance of stainless steel 316 can be enhanced through the metal coating by hydroxyapatite-chitosan composite with composition ratio of hydroxyapatite (gram) and chitosan 3% (mL) 0.2:0, 0.2:0.1, 0.2:0.5, 0.2:1.0, and 0.2:1.5. Besides improving the corrosion resistance of metal, the presence of chitosan also maintain the position of hydroxyapatite on metal surfaces. Corrosion resistance increases with increasing amount of chitosan added and the best composition of hydroxyapatite-chitosan composite was 0.2:1.0.
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