Judul: Pemanfaatan Ruang oleh Bekantan (Nasalis larvatus Wunnb) pada Habitat Terisolasi di Kuala Samboja, Kalimantan Timur
Abstrak: Proboscis monkeys (Nasalis larvatus Wurmb) is an endemic primate species to the island of Borneo and has been classified as endangered species by IUCN. Fourty percent of this habitat has been lost and only 4.1% of this habitat occurs within designated conservation areas. Kuala Samboja River is an unprotected habitat of proboscis monkey. This area was narrow, isolated, and fragmented. The objectives of the research were to obtain habitat conditions, population, food source, and space use. Data were collected through vegetation analysis by line-plot sampling method, activity budget and use of space by instantaneous sampling method, whereas food sources by individual activity records of feeding (IARF) method. The groups were observed were Stan, Zacky, and Raja. The results of this study showed that the community of habitat are dominated by Sonneratia caseolaris, Cerbera manghas, Vitex pinnata, and Elaeocarpus stipularis. Twenty one of plant species were found as food sources, five of those were preferred i.e. S. caseolaris, V. pinnata, Deris sp., Hevea braziliensis, and Avicenia cf. officinalis. The population of proboscis monkey more than 143 monkeys, 98 monkeys divided to 9 groups (6 one-male groups, 3 all-male groups), whereas 45 monkeys unidentified. Generally, the monkeys spent more time for feeding in the morning and afternoon and resting in noonday. Feeding and moving activity of female greater than male but resting was lesser, whereas social activity was done by female only. Each mean daily range groups were 289 m (Stan), 260 m (Zacky), and 449 m (Raja), while home range size were 4.92, 4.52, and 6.92 ha, respectively. The groups of Stan, Zacky and Raja spent most of their time at heights of 9-12 m, 0-6 m, and 3-9 m, respectively. Use of canopy stratum influence by habitat conditions, temperature, blown of wind, and predators.
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Judul: Habitat Suitability Modelling of Proboscis Monkey (Nasalis larvatus Wurmb, 1781) in Sekonyer River Tanjung Puting National Park, Central Kalimantan
Abstrak: Bekantan (Nasalis larvatus) merupakan spesies endemik pulau Kalimantan yang meliputi wilayah Indonesia, Malaysia, dan Brunei. Sebaran spesies ini terbatas pada habitat tertentu yang meliputi hutan bakau, hutan rawa, dan hutan riparian. Laju deforestasi habitat bekantan cukup tinggi sehingga berdampak pada penurunan populasi bekantan. Penelitian dilakukan pada bulan Februari-April 2020, dengan melakukan pengamatan di sepanjang aliran Sungai Sekonyer untuk mengetahui sebaran dan kondisi habitat. Analisis MaxEnt dilakukan untuk mendapatkan model serta nilai kontribusi variabel kesesuaian habitat. Hasil penelitian menunjukkan terdapat 47 jenis tumbuhan dari 27 famili yang 4 diantaranya merupakan pakan paling disukai bekantan. Kondisi habitat di Kawasan hutan sekitar Sungai Sekonyer dapat dikatakan baik, dilihat dari nilai kerapatan yang tinggi dari setiap tingkat pertumbuhannya. Habitat bekantan di Sungai Sekonyer sudah sesuai, dilihat dari masih tersedianya sumber kebutuhan hidup bekantan seperti sumber air, pakan, dan tempat berlindung. Model kesesuaian habitat bekantan dapat diterima dengan nilai AUC sebesar 0,966. Variabel kesesuaian habitat bekantan yang memiliki kontribusi paling besar adalah sungai dan tutupan lahan hutan rawa., he proboscis monkey (Nasalis larvatus) is an endemic species to Borneo's island and is largely confined to mangrove, riverine, and swamp forests. The rate of deforestation and habitat loss of the proboscis monkey is a significant threat to decreasing their population. This research was conducted during February-April 2020 by making observations along the Sekonyer River of Tanjung Puting National Park to determine the distribution and condition of the habitat. Using the maxent analysis, the model and the value of the contribution of the habitat suitability variable were obtained. There were 47 species of vegetation (27 families), four species were the most preferred food of proboscis monkeys. Habitat conditions in the forest area around the Sekonyer River were still quite good, seen from each growth rate's high-density value. The proboscis monkey habitat in the Sekonyer River was suitable, as seen from the availability of sources of life necessities such as water, food, and shelter. The proboscis monkey's habitat suitability model was acceptable with an AUC value of 0.966. The proboscis monkey's habitat suitability variables that had the most significant contribution were rivers and swamp forest land cover.
Keyword: Habitat suitability, proboscis monkey, Tanjung Puting National Park

Judul: Characterizations of low alloy steel sae 4422  plated with chromic acid (Cro3)
Abstrak: Characterizations of low alloy steel SAE 4422 plated with chromic acid (CrOrO3) was use Optical Microscopy (OM), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), RD),Energy Dispersive Analysis of X-Ray (EDAX), Hardness Test and Roughness Test. Microstructures analysis exhibits cracks and grain boundaries microcracks as a characteristics of chrome metal found at plating metal. Perlite and Ferrite as grains of steel found at base metal with grain boundaries around it. Phase analysis of plating metal appropriate to chrome metal with lattice constant (a) is 2.559 Å and phase analysis of base metal appropriate to iron ferrite with lattice constant (a) is 3.318 Å. Both plating and base metal have cubic system. Chemical analysis of plating metal at surface section exhibits that cracks area have highest value of carbon element compare with grains and grains boundaries area. While chemical analysis of base metal at cross section exhibits that perlite have highest value of carbon element compare with ferrite and grain boundaries. The hardness value of plating metal at surface section and cross section are 753 and 637 VHN. While, the hardness value of base metal and interface area at cross section are 205 and 373 VHN. The roughness value at measurement points of chrome surface for as received sample are 0.445 μm. Observation used Optical Microscopy and Scanning Electron Microscopy exhibits surface irregularities combine to form surface texture of plating metal at surface section.
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