Judul: Karakteristik Struktur Nano Dinding Sel dan Kaitannya dengan Sifat-sifat kayu (studi kasus kayu jati klon umur 7 tahun)
Abstrak: Recently, production of teak wood has been decreased and failured to fulfill market demands. Improvement in silviculture treatment shortened teak rotation turning it into fast growing species with the wood quality similar to its origin. Most of research on wood quality of teak (Tectona grandis L.f.) were focused on determining physical properties (density and specific gravity), wood structure (fiber dimension and Microfibril Angle (MFA)) and mechanical properties (Modulus of Elasticity, MOE and Modulus of Rupture, MOR). Variation in terms of wood qualities was widely observed. However, understanding the causes of the variation patterns of wood quality at the nano level is still lacking. This research aims to analyze growth variation and wood quality (nanostructure) from two different spacings (3 m x 3 m and 2 m x 6 m) and two different origins of clones, i.e Cepu and Madiun. The teak samples were taken from 7-years-old clonal trials in the research site of Watu Sipat Forests, Biotechnology and Forest Tree Improvement Research Facilities in Yogyakarta. Results showed that fenotype does not affect wood quality. Nanostructure of fast growing teak has influenced wood strength and durability. MOE was influenced by density, MFA, degree of crystallinity and width of cellulose crystallites. Apart of these findings, this research also highlighted the presence of preservative that could be detected in cell wall of wood through structure and dimension of cellulose crystallinity. In conclusion, wood quality characteristics from clone of Madiun was better than that of clone of Cepu, particularly at the spacing of 2 m x 6 m. This spacing, therefore, is considered importantly for economic, ecological and wood quality cloned teak development.
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Judul: Kajian Perbandingan Struktur Anatomi Serta Sifat Pisis dan Sifat Mekanis Antara Kayu Jati (Tectona grandis L.f.) Unggul Dengan Kayu Jati Konvensional Pada Kelas Umur I.
Abstrak: Wood structure, and some important physical and mechanical properties of 3 years old tissue cultural teak wood (Tectona grandis L. f) were studied and compared to those of 3 and 8 years old conventional ones. All samples were obtained from one and close area in Semarang (Central Java). The result as follow: a) All wood samples studied were juvenile since wood density and fibers length are fluctuate and tend to increase from pith towards the bark, b) Both, 3 years old tissue cultural and conventional teak woods have no heartwood at the center nor the end of the stem, besides on their basal area (29.81% in tissue cultural teak wood, and 25.00% in conventional one). While, the basal and center area of 8 years old conventional teak wood consisting of 58.23% and 46.30% heartwood, respectively, c) Latewood portion in tissue cultural teak was lowest. Between early and latewood in this teak was unclear and was not distinguished well, d) Wood texture among the samples was moderate. The finest was found on tissue cultural teak and the roughest on the conventional 3 years old, e) Based on their average in wood density, specific gravity, modulus of elasticity and modulus of rupture, it can be said that quality of tissue cultural teak wood was similar to that of 3 years old conventional one, but much lower than that of 8 years old conventional teak wood. Even the stem diamter between 3 years tissue cultural teak wood and 8 years old conventional one was similar physically, it can be said that the quality of teak wood from tissue culture treatment studied is much lower than that of the conventional one. In fact, their anatomical characteristics (wood structure), or physical and mechanical properties were similar and were not significantly different to those of 3 years old conventional teak wood.
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Judul: Dynamical System of Hepatitis B in Three Groups with Vaccination
Abstrak: The aim of this study is to modify the hepatitis B transmission model in three age groups involving vaccination from the model conducted by Zhoe and Zhang.The method used is to analyze the stability of the fixed point and its basic reproduction number (R_0). Performed stability analysis and numerical simulation to see population dynamics. Next, a sensitivity analysis of the parameters was carried out to see its effect on R_0. From the analysis obtained two fixed points, namely non-endemic and endemic fixed points. Non-endemic fixed points are locally asymptotically stable if R_0 <1 Meanwhile, the endemic fixed point is locally asymptotically stable if R_0 > 1. Hepatitis vaccination affects the number of susceptible population, because the more successful the vaccination, the smaller the number of susceptible populations so that the smaller the population will be infected.
Keyword: Dynamic, Hepatitis B, Vaccine, Mathematical model