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: Physical, Mechanical Properties and Durability of Impregnated Sengon Wood by Nano Silica orignated from Betung Bamboo Leaves
Abstrak: Sengon (Falcataria moluccana Miq.) merupakan jenis kayu cepat tumbuh yang memiliki beberapa kelemahan, yaitu berat jenis, kekuatan, keawetan, kerapatan dan stabilitas dimensi yang rendah. Penelitian ini bertujuan untuk menganalisis pengaruh perlakuan impregnasi menggunakan monoethylene glycol (MEG) dan nano silika daun bambu betung terhadap sifat fisis, mekanis dan keawetan kayu sengon. Salah satu metode modifikasi kayu adalah impregnasi. Proses impregnasi memiliki keunggulan yaitu dapat meningkatan kerapatan dan kekerasan kayu dengan memasukkan polimer ke dalam struktur kayu. Larutan impregnasi yang digunakan yaitu kontrol (tanpa perlakuan), MEG, MEGSilika 0.5% dan MEGSilika 1%. Proses impregnasi dimulai dengan pemberian vakum 0.5 bar selama 60 menit dan dilanjutkan dengan pemberian tekanan 2.5 bar selama 120 menit. Hasil penelitian menunjukkan perlakuan impregnasi MEG dan nano silika berpengaruh nyata dan meningkatkan nilai weight percent gain (WPG), kerapatan, perubahan warna (ΔΕ), MOE, MOR, kekerasan dan persentase mortalitas rayap tanah Coptotermes curvignathus serta menurunkan persentase kehilangan berat pada kayu sengon. Secara keseluruhan perlakuan MEGSilika 1% merupakan perlakuan yang paling optimum untuk kayu sengon yang berumur 5 tahun, Sengon (Falcataria moluccana Miq.) is fast growing wood species which has inferior characteristics i.e. low specific gravity, strength, durability, density and dimensional stability. The objective of this study was to analysis the effect of monoethylene glycol (MEG) and nano silica originated from betung bamboo leaves impregnation treatment on physical, mechanical properties and durability of sengon wood. One of wood modification methods is impregnation. Impregnation process could increase the wood density and hardness by introducing polymer into wood structure. The impregnation solution were consisted of water treated (untreated), MEG, MEGSilika 0.5% and MEGSilika 1%. The impregnation process was initiated by applying 0.5 bar of vacuum for 60 min and followed by 2.5 bar of pressure for 120 min. The results showed that MEG and nano silica impregnation treatment had significant effect on and increased weight percent gain (WPG), density, color changes (ΔΕ), MOE, MOR, hardness and mortality percentage of termite Coptotermes curvignathus and decreased weight loss percentage. MEGSilika 1% was the optimum treatment for of 5-year-old sengon wood.
Keyword: daun bambu betung, impregnasi, keawetan, nano silika, sengon, betung bamboo leaves, durability, impregnation, nano silica

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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