Judul: The Effect of Ammonia Residual to The Subterranean Termite (Coptotermes curvignathus Holmgren) Mortality in Several Species of  Wood Community Forest
Abstrak: INTRODUCTION : Nowadays, the interests of fumigation has increased along with the establishment of various intenational regulations, such as International Standard for Phytosanitary Measure (ISPM) No. 15 for wood packaging (Guidelines for Regulating Wood Packaging Material in International Trade) in 2002. ISPM-15 requires that all wood packaging must get special treatment, that is heat treatment or fumigation with methyl bromide. However, application of fumigation with methyl bromide has been limited because the effect of methyl bromide that can eradicate the ozone layer. It is necessary to have an alternative fumigant that is environmental friendly, one of which is ammonia. However, the use of ammonia has likely caused effects to the timber, one of which is the residue left in the timber. The residue will determine whether it could become an ideal fumigant. This study objective is to determine the effect of residue from ammonia fumigation, especially to subterranean termite Coptotermes curvignathus mortality in several species of wood community forest (Manii, Mindi, and Durian). MATERIAL AND METHODS : This study conducted a research to determine the effect of ammonia residual on the mortality of termites on the Manii, Durian, and Mindi woods. We performed testing of natural durability of wood by using ASTM D 3345- 2008. Further research conducted on the effect of ammonia fumigation against termite attack that inserted into the hole in the wooden blocks with the depth of 20 cm and the hole distance each other is 1 cm, 3 cm, and 5 cm from the surface. Fumigation process using 2 litres, 4 litres, 6 litres, 8 litres, and 10 litres ammonia inside 2 m x 1 m x 1 m fumigation chamber for 4 days. After 4 days of exposure, aeration was perfomed for 24 hours and then the effect of ammonia residual was tested by putting back termites into the block of wood that has been used in the fumigation process earlier and exposed for 7 days. Parameters measured in those testing was termite mortality after exposure for 4 days and 7 days. RESULT AND DISCUSSION : The results showed that Manii had a lower durability level than Mindi and Durian. Fumigation test results showed that wood density may effect the percentage of termite mortality. In addition, wood that had been exposed to 2 litres ammonia had higher mortality than the control treatment (31.11%). 6 litres ammonia resulted 100% mortality of termites in the 2 m x 1 m x 1 m fumigation chamber. The results of ammonia residual tests obtained 100% mortality of termites for each species, the volume of ammonia, and the hole distance used in this study. Test results showed that the ammonia has residual effect. The ammonia residual causes the smell of wood so that necessary efforts to eliminate it had to be done.
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Judul: Pengaruh Fumigasi Amonia terhadap Sifat Fisis, Mekanis dan Keawetan Tiga Jenis Kayu Hasil Tanaman
Abstrak: Recently, sengon (Falcataria moluccana), karet (Hevea brasiliensis) and mangium (Acacia mangium) woods became popular for many wood industries in Indonesia due to the lack of better quality of wood. Sengon wood is for pallet and/or packaging material, while karet- and mangium woods are for meubel and furniture manufacturing. These three wood species belong to non durable wood: sengon and mangium woods are commonly obtained from the younger trees (four to less than 10 year-old), while karet wood even though it is around 25 year-old, it is attacked easily by blue-stain and other destroying fungus. In order to improve the quality of these three woods, fumigation technique using ammonia was performed. Since effect of ammonia fumigation on physical-mechanical properties and natural durability of wood, especially the wood from plantation, was not study well, therefore, the aim of this study was focussing on the above aspect. It is hope that fumigation process applied has no negative effect on wood quality. The main material used was heartwood portion from the middle part of tree stem of sengon, karet and mangium. All tree species were obtained from rural forest of surrounding areas of IPB Darmaga Campus. There was no information about tree age, but their diameters were around 20-25 cm. The parameters studied consist of wood moisture content (MC), specific gravity (BJ), modulus of elasticity (MOE), modulus of rupture (MOR), maximum compression strength parallel to the grain (σtk//), hardness in radial and tangential surfaces and also the weight loss. All sample size and shape and also the testing procedure were carried out following the ASTM-D143 94 in 2007, with four replications. Data were then analyzed with a random two-factor factorial design using SAS 9.1.3 and Microsoft Excel 2010. The result showed that ammonia fumigation is significantly affects wood MC and weight loss. Wood MC and weight loss were also influenced by wood species, while interaction between wood species and ammonia fumigation was not. After fumigation, wood MC tended to increase (8.40-22.80%), while the weight loss tended to decrease (27.26-56.48%). The highest increasing of MC was found on mangium wood, while the lowest on rubber wood. After fumigation, karet wood was more durable compared to sengon wood. The research also showed that ammonia fumigation and the interaction between wood species and fumigation treatment have no significant effect on SG, MOE, MOR, σtk// and wood hardness. SG and all mechanical properties studied were influenced only by wood species.
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Judul: Invers dari Matriks Tridiagonal Jacobi
Abstrak: Suatu matriks berukuran n×n dinamakan matriks tridiagonal jika untuk . Karya ilmiah ini memberikan algoritma yang mudah untuk menemukan invers ( dari matriks tridiagonal Jacobi yang simetrik dan nonsimetrik. Setiap elemen pada matriks tridiagonal ini adalah bilangan real. Terdapat 3 lema dan 2 teorema untuk menentukan . Lema pertama menunjukkan persamaan utama dalam membuktikan lema-lema dan teorema-teorema selanjutnya. Invers dari matriks yang simetrik dibuktikan oleh lema kedua yang menunjukkan elemen-elemen baris ke- dari . Selanjutnya, lema kedua dilengkapi dengan teorema pertama yang menunjukkan elemen-elemen dengan . Invers dari matriks yang nonsimetrik dibuktikan oleh lema ketiga yang menunjukkan elemen-elemen dengan dan elemen-elemen dengan dibuktikankan oleh teorema kedua.
Keyword: symmetric, nonsymmetric, matrix