Judul: Mempelajari pembuatan bahan dasar cat emulsi dengan metode kopolimerisasi lateks alam iradiasi
Abstrak: Cat lateks merupakan salah satu produk olahan dari lateks yang memiliki beberapa kelebihan dibanding jenis cat lain, yaitu formulasinya menggunakan air, terhindar dari kemungkinan keracunan dan bahaya kebakaran serta memiliki kemampuan dapat dicuci (washable). Selama ini, bahan dasar yang digunakan pada pembuatan cat lateks umumnya berupa lateks karet yang telah divulka- nisasi dengan menggunakan belerang serta dikopolimerisasi dengan beberapa jenis monomer. Pada penelitian ini digu- nakan metil metakrilat dan stiren sebagai monomernya. Proses vulkanisasi lateks serta kopolimerisasi dilakukan dengan metode iradiasi. Tujuan percobaan ini ialah untuk mempelajari cara pembuatan dan sifat-sifat cat emulsi dari bahan lateks. karet alam iradiasi, kopolimer lateks alam iradiasi-sti- ren, kopolimer lateks alam-stiren dan kopolimer lateks alam-metil metakrilat. ...
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Judul: Kajian pembutiran lateks alam iradiasi dan kopolimernya
Abstrak: Karet adalah salah satu komoditi ekspor Indonesia. Pada tahun 1994 total ekspor karet alam olahan pada bulan Januari Juni mencapai 602 128 ton (Anonim, 1994). Untuk mempermudah proses pembuatan barang-barang dari karet yang memerlukan proses pencampuran, maka dilakukan pembutiran karet. Karet butiran ini mudah dicampur dengan bahan-bahan kimia dan dikontrol selama proses produksi. Secara umum pembutiran lateks dapat dilakukan dengan cara mekanis, kimiawi mekanis, dan kimiawi. Tujuan penelitian ini adalah mempelajari pembuatan butiran karet dari lateks pekat (LK), lateks alam iradiasi (LI), kopolimer lateks alam polimetil metakrilat (LM), dan kopolimer lateks alam polistirena (LS) dengan metoda pembutiran secara kimia, serta menganalisa mutunya. Parameter yang dianalisa ialah rendemen, kadar abu, persen diameter butiran yang berukuran lebih kecil dari 0.5 cm, tegangan putus, perpanjangan putus, dan Differential Scanning Calorimeter (DSC). Uji statistik yang digunakan ialah uji t berpasangan dengan derajat bebas 2 untuk membandingkan kedua jenis lateks...
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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