Judul: Kadar Komponen Kimia Kayu dan Kulit Jati (Tectona grandis Linn f.) Asal Jawa Barat dan Jawa Timur
Abstrak: Teak wood (Tectona grandis Linn f.) is well known as a high value of wood species due to high durability, dimensional stability, and strength, as well as high value in the decorative properties of wood. The processing of teak wood into various wood products produces a lot of biomass waste, such as bark and wood residue. The potential utilization of teak wood biomass residue is not only as a raw material of wood products but also as natural chemical resources. This research aims to analyses chemical components of bark and wood residue of teak wood from West and East Java, including holocellulose, alpha-cellulose, Klason lignin, acid soluble lignin, syringyl-guaiacyl ratio of lignin, and extractives content. Bark contains higher holocellulose and alpha-cellulose, and lower lignin content than that of wood residue. In addition, teak bark lignin consists of siringil-guaiacyl ratio higher than lignin of wood sample. Generally, teak wood from West Java contains higher polysaccharides and extractives with lower lignin content than teak wood from East Java. Due to high content of polysaccharides and low content of lignin, teak bark biomass might be promoted as raw materials for pulp and bioethanol productions.
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Judul: Komponen Kimia Kayu Jati (Tectona grand& L. f.) Pada Berbagai Kelas Umur Dari KPH Purwakarta
Abstrak: Various age class of Teak wood (Tectona grandis L J), i.e. the age class of I, 11, I11 and IV were investigated for their chemicals content. The sample were taken from the forest district of Punvukartu in West Java. All chemicals content were determined based on approriate Tappi and ASTM standard. The present research is intented to determine the possibility of reducing the harvesting rotation of teak woodfrom Punvakarta (West Java). It was found that holocellulose, cellulose, a-cellulose, Klasan lignin, Spectrophotometric lignin, hernicellulose, extractive (ethanol : benzene = 1 : 2), ash content, solubili@ in NaOH I%, solubility in cold water and solubility in hat water ranged from 68.69-70.65%, 43.57-45.25%, 37.41-39.1 7%, 24.73-28.94%, 23.99-24.26%, 24.29-27.08%, 3.16-1 0.56% 0.58-0.87%. 13.61-19.32%, 4.82-6.46% and 5.23-6.91 %, respectively. Stutistical evaluation of the chemical content data along with anatomy, mechanics and phjlsical properties indicated that the teak wood from Punvakarta may be harvested at the age class of 111.
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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