Judul: Ekstraktif Kulit Kayu Samak (Syzygium inophyllum DC.) sebagai Pewarna Alami Kayu.
Abstrak: Natural color of the wood is one of the characteristics that make certain types of wood very attractive aesthetically and has a high economic value. Staining is one of the finishing processes on wooden products, to obtain more attractive colors. Nowadays, the use of natural dyes in the handicraft and furniture industry is increasing. The aim of this research is to produce natural dyes from samak bark and to test the quality of the color, the physical properties, the mechanical properties, and the resistance to wood destroying organism of stained jabon wood. Natural dyes was obtained by extracting samak bark (S. inophyllum) using water , ethanol and water-ethanol mixture (3:1, 1:1 and 1:3 v/v) solvent. The staining process was applied to jabon wood by hot soaking for 3 hours and cold soaking for 72 hours, respectively.. The stained jabon wood performance were evaluated including the color leaching test in hot water, cold water, teepol soap solution, and the color change by acid solution. The color leaching assessed by determination of color changes using the CIELab method, FTIR analysis. Staining of jabon wood with samak bark extract obtained from water - ethanol ( (3:1 v/v) extraction showed a good coloring performance and high color stability (less leaching ability) . In addition, the resistance of stained jabon wood to biodegradation (termites and fungi) increases significantly. . The catechol as the main component in the extract seems to be compound played, not only, as a natural dye but also as an antitermite and fungi’s growth inhibitor. However, there was not effect of extracts to the physical properties (specific gravity and density) and mechanicals properties (MOE, MOR and hardness) of the stained wood.
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Judul: Pengawetan Kayu Jabon (Anthocephalus cadamba Roxb. Miq) dengan Bahan Pengawet Diffusol-CB
Abstrak: Jabon wood is a fast growing species that has a low mechanical physical properties and low durability. This study aims to determine the effect of Diffusol- CB on the durability of jabon wood in parts of pith to bark. The jabon trees in the age of 5, 6 and 7 years old and a parts of bottom, middle and top were used in this study. Other material is preservative Diffusol-CB with concentration of 5%. Preservation method used the cold bath for the period of 2 days (48 hours) and the durability test was conducted for 3 months in the field using procedure of American Society for Testing and Material (ASTM) D 1756 2008. The results showed that the value of retention in the average of 5.77 kg/m3 for wood samples near the bark and of 5.19 kg/m3 for the sample near the pith. The highest retention was 7.30 kg/m3 for the bottom part of jabon 6 years. Meanwhile jabon wood at the age of 7 years near the pith had the lowest retention 2.61 kg/m3. The experimental results also showed that the weight loss of untreated jabon wood was in the average of 52.71%. Maximum weight loss of 87.74% was found in the middle part of jabon wood near the bark at the age of 5 years. Meanwhile the lowest weight loss 14.77% retained by jabon wood at the bottom part near the bark for the age of 7 years. The jabon wood treated by diffusol CB 5% suffered weight loss in the average of 2.55%. This results give an indication that the Diffusol-CB with a concentration of 5% can increase the durability of jabon wood against termite attack. Degree of protection results showed that the degree of damage for untreated jabon wood was very large. Meanwhile the treated jabon wood didn’t show any damages on the samples.
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Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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