Judul: Pengawetan Kayu Sengon (Falcataria moluccana Miq.) dengan Diffusol CB
Abstrak: Innovation in wood science and technology could improve the service life of sengon wood (Falcataria moluccana Miq.) through the wood preservation process, especially with a cold immersion method. Analysis of data was conducted in a descriptive with the retention, weight loss, grave yard test valuation, moisture content, density, specific gravity, MOE and MOR parameters of the sengon wood (Falcataria moluccana Miq.). Samples were prepared with 3 combinations of variant consisting of: (a) Variant of wood inside (sapwood and heartwood); (b) Variant of age (5, 6, 7 years); and (c) Variant of height position (bottom, middle, and upper). The application of preservative diffusol CB through the cold immersion method on sengon wood age 5, 6, and 7 years can improve the physical properties (moisture content, specify gravity and density of the wood), and durability of wood (retention, weight loss, grave yard test), as well as could reduce the organism attack (termite Macrotermes gilvus and fungi Pycnoporus cinnabarinus) when compared to control. Mechanical properties (MOE and MOR) sengon wood in bottom position of inclined downward from the pith to bark.
Keyword: grave yard test, cold immersion, diffusol CB, Falcataria moluccana

Judul: Color Change and Resistance of Sengon and Mangium Wood Preserved by Imidacloprid through the Grave Test
Abstrak: Sengon (Falcataria moluccana [L.] Nielsen) dan mangium (Acacia mangium Willd.) merupakan kayu yang memiliki tingkat ketahanan yang rendah terhadap serangan organisme perusak. Ketahanan kayu dapat ditingkatkan dengan bahan pengawet imidakloprid. Penelitian ini bertujuan mengetahui perubahan warna yang terjadi setelah uji kubur 12 bulan dan menganalisis pengaruh pengawetan kayu menggunakan imidakloprid terhadap tingkat ketahanan kayu sengon dan mangium akibat serangan rayap tanah. Pengawetan kayu menggunakan metode vakum-tekan. Pengujian tingkat ketahanan kayu mengacu pada ASTM D 1758-06 yang dimodifikasi. Perubahan warna yang terjadi setelah uji kubur memiliki nilai yang besar. Nilai perubahan warna pada semua perlakuan menunjukkan hasil tidak berbeda nyata. Kadar air pada kondisi kering oven menunjukkan hasil kayu mangium lebih tinggi dari kayu sengon pada kedua perlakuan. Nilai retensi kayu sengon lebih rendah dibandingkan kayu mangium. Pengawetan menggunakan imidakloprid membuat kerapatan kayu menjadi meningkat. Kehilangan berat paling besar yaitu sengon kontrol dan terkecil yaitu mangium imidakloprid. Tingkat ketahanan kayu paling tinggi yaitu mangium imidakloprid dan paling rendah sengon kontrol., Sengon (Falcataria moluccana [L.] Nielsen) and mangium (Acacia mangium Willd.) are woods that have a low level of resistance so they are easily attacked by destructive organisms. The termite resistance of wood can be increased using imidacloprid. This study aims to determine the color change that occurs after the 12 months grave test and to analyze the effect of wood preservation using imidacloprid on the resistance of sengon and mangium woods due to subterranean termite attack. Preservation of wood using the vacuum-pressedmethod. The termite resistance test of wood using the modified ASTM D 1758-06. The color change that occurred after the grave test had a large value. The value of color change in all treatments showed no significant difference. The moisture content in oven dried showed thatmangium wood was higher sengon wood in both treatments. The retention value of sengon wood was lower than mangium wood. Preservation using imidacloprid increased the density of the wood. The biggest weight loss was control sengon and the smallest was mangium imidacloprid. The highest protection level was mangium imidacloprid and the lowest was sengon control.
Keyword: color change, imidacloprid, mangium, sengon, wood preservation

Judul: igenvalues and Eigenvectors of Tridiagonal Matrix with Non Constant and Recurrent Diagonal Entries.
Abstrak: Matriks tridiagonal adalah suatu matriks yang mempunyai entri-entri bernilai nol kecuali pada diagonal utama, di bawah diagonal utama (subdiagonal) dan di atas diagonal utama (superdiagonal). Entri pada diagonal utama tidak konstan dan berulang. Setiap entri pada matriks tridiagonal ini adalah bilangan kompleks. Dalam karya ilmiah ini, akan dibuktikan 3 teorema untuk menentukan nilai eigen dengan 2 kasus dan 1 teorema untuk menentukan vektor eigen. Teorema pertama menentukan polinomial karakteristik dari matriks tridiagonal. Polinomial karakteristik dari matriks tridiagonal tersebut digunakan untuk menentukan nilai eigen pada teorema kedua dan ketiga serta menentukan vektor eigen pada teorema keempat
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