Judul: Analisis kestabilan model infeksi virus leukemia feline
Abstrak: Virus leukemia foline adalah virus penyebab kanker darah dan kerusakan swnsum tulang pada kucing. Virus ini menyebar secara pidemi melalui air liur dan lendir hidung lewat interaksi antarkucing. Penyebaran virus leukemia feline ini digarnbarkan dengan suatu model matematis yang memuat sejumlah persarnaan diferensial biasa non linear yang didasarkan pada prinsip-prinsip epidemi standar (Murray, 1989). Model ini mendeskripsikan penyebaran virus lellkelllia feline dalarn suatu populasi konstan yang dihubungkan dengan waktu.
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Judul: Analisis kestabilan model feline immunodeficiency virus (Fiv)
Abstrak: Feline Immunodeficiency Virus (FIV) dikenali sebagai virus yang menyebabkan penyakit AIDS ( penyakit hilangnya kekebalan tnbnh ) pada kocing. FIV merupakan bagian dari lentivirus subfamily dari retrovirus, yang didalamnya termasuk retrovirus pada manusia (HIf/) dan retrovirus pada kera (SIf/). Melalui interaksi antar kocing, FIV menyebar secara epidemi melalui gigitan. Penyebaran FIV ini digambarkan dengan suatn model matematis yang memuat sejumlah persamaan diferensial biasa non linear yang didasarkan pada prinsip-prinsip epidemi standar. Model iui mendeskripsikan penyebaran FIV dalam suatu populasi konstan. Populasi konstan ini dibagi menjadi dua kelas individu yakui rentan, terinfeksi.
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Judul: Properties of Inner Part of Oil Palm (Elaeis guineensis Jacq.) Trunk Compregnated by Methylene Diphenyl Diisocyanate and Its Application as Blockboard
Abstrak: Inner part of oil palm (Elaeis guineensis Jacq.) trunk (IOPT) is still not optimally utilized. The IOPT can be used as raw material for wood and composite products such as blockboards to increase its added value. However, the IOPT has low density, strength, and dimensional stability. The physical and mechanical properties of the IOPT can be improved by wood modification techniques such as densification, impregnation, and compregnation. Densification has drawbacks such as the occurring of a spring-back so that the modification results are not fixed. Meanwhile, impregnation is a technique of filling wood voids with thermosetting resin to increase density. The combination of impregnation and densification is called compregnation. Compregnation has a lower spring-back than densification due to the presence of impregnants. So far, the impregnants used in the impregnation or compregnation techniques are formaldehyde-based resins which are not environmentally friendly. Therefore, research on impregnation using materials that are more environmentally friendly is important. This study aims to improve the properties of IOPT through impregnation, densification, and compregnation methods and its application as a blockboard core. The research was divided into three stages, that is (1) determination of methylene diphenyl diisocyanate (MDI) concentration as an impregnant in the IOPT (2) determination of the optimum compression ratio in the densification and compregnation of IOPT, and (3) characterization of physical and mechanical properties of blockboard with a compregnated IOPT as a core. The impregnation of IOPT was carried out by the vacuum-pressing method. The impregnation process was initiated with a 7.6 MPa vacuum process for 15 minutes. Impregnation using MDI resin with concentrations of 10% and 20% were carried out at a pressure of 1.2 MPa for 60 minutes. Densification with a target thickness of 1.5 cm and compression ratios of 20% and 30% was carried out using hot pressing at a temperature of 150 °C and a pressure of 8 MPa for 30 minutes. Compregnation is carried out by a combination of impregnation and densification as described above. The physical and mechanical properties of the modified IOPT were carried out according to the ASTM D 143-2000 standard. The resistance of the MDI impregnated IOPT against subterranean termites was tested based on the SNI 7207-2014 standard. The blockboards were made from the compregnated IOPT as the core and the mangium wood (Acacia mangium Willd.) veneer as the face layers. Total blockboards layers are three and seven layers. The IOPT and mangium wood veneers were glued with MDI resin with a spread rate of 200 g·m-2 and hot- pressed at 100 °C and a pressure of 0.5 MPa for 4 minutes for three-ply blockboard and 8 minutes for seven-ply blockboard. Physical and mechanical properties of blockboards were tested based on Japanese Industrial Standard (JIS) A 5908-2003 and Japanese Agricultural Standard (JAS) 232-2003. The results showed that the impregnation using MDI improved the physical and mechanical properties of the IOPT at the bottom, middle, and top parts. The increase in the physical and mechanical properties of the IOPT was higher by increasing MDI concentration. The MDI impregnated IOPT had a higher density values and a lower
Keyword: blockboard, compregnation, inner part of oil palm trunk, methylene diphenyl diisocyanate