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: Dimensi Serat, Sudut Mikrofibril dan Beberapa Sifat Fisis Kayu Jati (Tectona grandis) Umur 29 Tahun
Abstrak: The aim of this research was to evaluate wood quality of planted teak through its fiber morphology, microfibril angle (MFA), moisture content (MC) in green condition, density as well as specific gravity (SG). The sample tree was obtained from IPB campus area which was planted in 1985 without any silvicultural treatment. Fiber length was measured by Schluze-macerated fiber, while anatomical structure and the MFA were observed through thin-sliced specimen. MC, density and SG of wood were measured by gravimetric method. Result shows that anatomical structure of 29 year-old of teak studied was similar to that of teak in general. Average values of fiber length, MFA, MC in green condition, density and SG were 948.12 um, 32.8o, 58.93%, 0.78 g/cm3 and 0.48, respectively. The wood belongs to the strength class of III. Even though the mature woods were not produce yet, density and SG of wood of > 8 cm from the pith tended to increase.
Keyword: wood density, fiber length, MFA, Tectona grandis, teak

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