Judul: Impregnation of Wood Preservatives Formula based on Wood Liquid Smoke into Suren Wood (Toona sureni Merr)
Abstrak: Indonesia memiliki iklim yang sesuai untuk kehidupan rayap sehingga beberapa jenis kayu di Indonesia lebih rentan terhadap serangan rayap dan membutuhkan modifikasi untuk meningkatkan ketahanannya. Salah satu proses modifikasi yang dapat dilakukan adalah modifikasi secara kimiawi yaitu impregnasi bahan pengawet. Berdasarkan penelitian terdahulu, proses pengasapan kayu dapat meningkatkan ketahanan kayu. Pada asap kayu terdapat beberapa senyawa kimia yang dicurigai berpotensi untuk dikembangkan menjadi formula bahan pengawet yaitu asam asetat dan benzofuran. Pada penelitian ini empat jenis bahan pengawet dengan formula tunggal yaitu asam asetat (A), guaiacol (B), benzofuran (C), dan furfuril alkohol (D), serta formula campuran keempat senyawa tersebut dengan kode E, F, G, dan H diformulasikan bahan pengawet dengan komponen kimia yaitu asam asetat, benzofuran, serta furfuril alkohol dan diuji kemampuannya dalam meningkatkan ketahanan kayu suren (Toona sureni Merr). terhadap serangan rayap tanah melalui uji laboratorium berdasarkan SNI 7207-2014. Impregnasi benzofuran secara tunggal pada sampel kayu menyebabkan peningkatan ketahanan kayu terhadap serangan rayap tanah. Sampel terimpregnasi asam asetat, guaiacol, dan furfuril alkohol memiliki persentase weight loss yang lebih rendah dibandingkan sampel tanpa perlakuan namun masih termasuk dalam kelas ketahanan yang sama seperti sampel tanpa perlakuan. . Kayu terimpregnasi formula bahan pengawet memiliki ketahanan terhadap serangan rayap tanah yang lebih baik dibandingkan kayu tanpa perlakuan. Hal tersebut dapat ditunjukkan dari nilai weight loss kayu terimpregnasi formula bahan pengawet yang lebih rendah. Peningkatan kelas ketahanan sampel hanya terjadi pada sampel terimpregnasi formula bahan pengawet dan bahan kimia benzofuran secara tunggal. Pengujian perubahan warna menunjukkan bahwa kayu suren terimpregnasi bahan pengawet mengalami perubahan warna besar serta memiliki tingkat kecerahan yang lebih tinggi dibandingkan kayu tanpa perlakuan. Berdasarkan penentuan perlakuan prioritas, formula bahan pengawet yang berpotensi untuk dikembangkan menjadi bahan pengawet adalah formula E dan H., Indonesia’s climate is suitable for termite life thus several species of woods in Indonesia is more vulnerable to termite attacks and requires modifications to increase their resistance. One of the modification processes that can be done is chemical modification. Based on previous research, smoked wood has higher resistance against subterranean termite attack. In wood smoke, several chemical compounds are suspected to have the potential to be developed into a preservative formula, specifically, acetic acid and benzofuran. In this study, these compounds were formulated as four wood preservative formula (E, F, G, and H) with chemical components, namely acetic acid (A), guaiacol (B) benzofuran (C), and furfuryl alcohol (D), and it was tested its ability to increase wood resistance against subterranean termite (Coptotermes sp.) attacks through laboratory tests based on SNI 7207-2014. Benzofuran impregnation into woods leads to higher resistance class against subterranean termite attacks. Impregnated woods with acetic acid, guaiacol, and furfuryl alcohol has lower weight loss value than untreated wood. However, impregnated woods with acetic acid, guaiacol, and furfuril alkohol belongs to the same resistance class as untreated wood. Impregnated suren (Toona sureni Merr) woods with preservative formula has better resistance against subterranean termite attacks than untreated wood. This can be shown from the lower weight loss value of impregnated woods. Higher resistance class only occurs on woods impregnated with wood preservatives formula and benzofuran. Color change testing
Keyword: Asap kayu, Bahan pengawet, Formulasi, Ketahanan, Rayap tanah, Formulation, Resistance, Subterranean termites, Wood preservatives, Wood smoke

Judul: Color Change and Resistance of Pine and Jabon Wood Preserved with Imidacloprid againts Subterranean Termites through Graveyard Test
Abstrak: Kayu pinus (Pinus merkusii Jungh. et de Vriese) dan jabon (Anthocephalus cadamba (Roxb) Miq.) termasuk kelas awet V yang rentan terhadap serangan organisme perusak, sehingga ketahanannya perlu ditingkatkan. Penelitian ini bertujuan menganalisis pengaruh bahan pengawet imidakloprid terhadap perubahan warna dan ketahanan kayu pinus dan jabon akibat serangan rayap tanah melalui uji kubur selama satu tahun. Pengawetan kayu menggunakan metode vakum tekan dengan bahan pengawet imidakloprid. Pengujian terdiri dari kerapatan, kadar air, retensi, perubahan warna, kehilangan berat, dan tingkat ketahanan kayu. Pengujian tingkat ketahanan kayu menggunakan standar ASTM D 1758-06 dimodifikasi. Hasil menunjukkan pada semua contoh uji setelah uji kubur terjadi perubahan warna dengan nilai perubahan warna (ΔE*) yang besar dan perubahan warna antar contoh uji satu sama lain tidak berbeda. Nilai retensi kayu pinus lebih rendah dibandingkan kayu jabon. Kayu pinus dan jabon kontrol dengan pengawetan imidakloprid berbeda nyata pada pengujian kerapatan, kadar air, kehilangan berat, dan tingkat ketahanan kayu., Pine (Pinus merkusii Jungh. Et de Vriese) and jabon (Anthocephalus cadamba (Roxb) Miq.) belong to durable class V which are susceptible to attack by destructive organisms, so their resistance need to be increased. This study aims to analyze the effect of imidacloprid as a preservative on discoloration and resistance of pine and jabon wood due to subterranean termite attack through a one-year grave test. The preservation of wood used the vacuum-pressed method with the preservative imidacloprid. The test consists of density, moisture content, retention, discoloration, weight loss, and wood resistance level. The protection level test of wood used the modified ASTM D 1758-06 standard. The results showed that after the grave test, all samples had a color change with a large color change va lue (ΔE*) and the color cha nges (ΔE*) of the samples were not different from one another. The retention value of pine wood is lower than jabon wood. Pine wood and control jabon with imidacloprid preservation were significantly different in tests of density, moisture content, weight loss, and wood protection level.
Keyword: discoloration, imidacloprid, jabon, pine, wood resistance

Judul: Bifurkasi Hopf pada Model Siklus Bisnis Kaldor Kalecki tanpa dan dengan Waktu Tunda
Abstrak: Business cycle model is one of dynamical system models in economic. One of the business cycles model is Kaldor-Kalecki model. Kaldor-Kalecki business cycle model that is written in delayed defferential equations, is a business cycle model that involves gross product and capital stock of a company. In this paper Kaldor-Kalecki business cycle model is analyzed using both nondelay and delay in time of capital stock. By Taylor expansion for the time delayed model, an analysis of stability around the fixed points has been done. Furthermore, by using Hopf bifurcation theorem, it can be shown that there exists periodic orbits and limit cycle. In the nondelayed model, changing the parameter of goods market could lead to the occurrence of Hopf bifurcation and the existence of limit cycle. Similarly, for the delayed model, it has been shown that changing the time delay parameter may result in the occurrence of Hopf bifurcation and limit cycle.
Keyword: