Judul: Pengaruh Penambahan Bahan pemucat terhadap Karakteristik Magnetic Filter Sludge Oil Hasil Cold Stripping
Abstrak: Rolling Oil mempakan pelumas yang digunakan pada proses penipisan pelat baja (Cold Stripping). Penggunaan Rolling Oil secara berulang menyebabkan minyak mengalanii kerusakan yang akan menumnkan kinerja pelumasan. Roiling Oil setelah digunakan didaur ulang kembali pada unit Roll Coolant Plant dengan proses separasi. Pada proses tersebut, dipisahkan antara fasa minyak, air, dan sludge.
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Judul: Pengaruh penambahan bahan pemucat terhadap karakteristik rolling oil bekas hasil cold stripping
Abstrak: Rolling oil digunakan di PT Krakakatau Steel untuk menipiskan baja dengan sistem penekanan. Penipisan dilakukan dengan cara melewatkan plat baja pada 5 buah stand yang masing-masing stand terdiri dari 2 buah work roll dan back up roll. Rolling oil berfungsi selain sebagai pelumas, juga memiliki efek mendinginkan dan untuk mengurangi gesekan antara permukaan plat dengan roll. Tujuan dari penelitian ini adalah untuk memurnikan rolling oil bekas agar memiliki karakteristik yang mendekati karakteristik rolling oil segar dengan cara pemucatan (bleaching). Jenis analisis yang dilakukan adalah Bilangan Asam, Bilangan Penyabunan, Bilangan Peroksida, Bilangan Iod, Bobot Jenis, Kadar Abu, Warna (% transmisi), Viskositas, Rendemen, Fraksi Tak Tersabunkan, Unsur Logam, dan Kromatografi Gas. Rancangan Percobaan yang digunakan pada penelitian ini adalah Rancangan Acak Kelompok Faktorial dengan 2 kali ulangan. Jenis minyak yang digunakan dibagi dalam dua blok, yaitu minyak tahap awal (K₁) dan minyak tahap akhir (K2) pada periode yang sama. Penelitian ini menggunakan dua jenis bahan pemucat, yaitu asam oksalat dengan konsentrasi, 0.25 persen, 0.5 persen, dan 0.75 persen, dan bentonit dengan konsentrasi 0.5 persen, 1.5 persen, dan 2.5 persen, serta kombinasi kedua bahan pemucat tersebut, dan diibandiingkan dengan tanpa penanbahan bahan pemucat. Hasil Analisis Sidik Ragam didapatkan bahwa kedua jenis bahan pemucat tersebut berpengaruh nyata terhadap Bilangan Asam, Bilangan Penyabunan, Rendemen, Warna (% transmisi), dan Kadar Abu. Bentonit cenderung menurunkan bilangan asam, bilangan peroksida, bobot jenis, rendemen, warna (% transmisi), kadar abu, unsur logam, dan cenderung menaikkan bilangan penyabunan...
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Judul: Studies on growth spurt and aging in higher primates
Abstrak: single measurement that best defines the health and nutritional status of children, just as it provides an indirect measurement of the quality of life of an entire population. The pattern of human growth reflects the biocultural evolution of our species. The human pattern of growth and development (ontogeny) appears to differ markedly from patterns of ontogeny in other primate species. Three studies are reported here which deal to the growth and development of human and chimpanzee (Pan troglodytes). These three studies allow us to contrast the phenomena of adolescence growth spurt and female elderly bone loss in chimpanzee and human as chimpanzee is the closest species to humans within extant nonhuman primates. In the first, a cross-sectional study of growth of the body size and somatotype of 363 Javanese girls and 299 Javanese boys aged 4 to 20 years from Magelang Regency, Indonesia was described. In the second, cross-sectional and longitudinal studies in the growth of chimpanzee second metacarpal bone linear dimensions from individuals aged 0 to 43.6 years were used for comparison. While in the third, cross-sectional and longitudinal studies in the growth of chimpanzee body size (body mass and anterior trunk length) and second metacarpal bone mineral content were derived. In measuring the second metacarpal dimensions and mineral content, a total of 568 radiographs of chimpanzee's proximodistal left hands were used. They were taken from 68 females and 49 males aged 0 to 43.62 years old. We applied an image analysis system, Scion Image Release Alpha 4.0.3.2 software for Windows to measure bone linear dimensions and bone mineral content. Humans present complex and sinuous growth curves for both body weight and height. A clear growth spurt could be demonstrated by cross-sectional analysis in our girl subjects at around aged 11.5 years and in our boy subjects at around aged 12.5 years. In longitudinal series, not in cross-sectional, several representative chimpanzees of both sexes showed a pre-adult growth spurt on the body sizes, bone dimensions and bone mineral content. They ranged at age 4.5 to 8.5 years. This underscore the fact that adolescent growth spurt in linear dimension was not a universal feature of anthropoid primate ontogeny. Bone loss is a well established characteristic of human female aging. Based on crosssectional analyses the sequential decline of bone mass in female chimpanzee may be said to be genuine. On the other hand, we found in adulthood through elderly, male chimpanzees show a longer plateau than female chimpanzee, that is, bone mineral content is maintained in male.
Keyword: Javanese children, growth spurt, chimpanzee, second metacarpal bone, bone loss, Higher Primates