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: Kadar Tektokuinon pada Ekstrak Kayu dan Kulit Jati (Tectona grandis L.f) Jawa Barat dan Jawa Timur
Abstrak: Tektokuinon merupakan senyawa utama dalam ekstraktif kayu Jati yang berperan terhadap keawetan alaminya. Kadar dan komposisi ekstraktif dapat dipengaruhi oleh jenis, umur, bagian dalam kayu, dan lokasi tempat tumbuh. Pengetahuan tentang kadar tektokuinon dalam kayu Jati berdasarkan lokasi dan bagian kayu yang berbeda akan menjadi informasi penting terkait sifat dasar kayu dan potensi pemanfaatan komponen kimia kuinon dalam kayu Jati. Penelitian ini bertujuan untuk mengukur kadar ekstrak kuinon dan tektokuinon dalam kayu dan kulit Jati asal Jawa Barat dan Jawa Timur dengan menggunakan pelarut etanol dan toluena. Ekstraksi dilakukan dengan metode sokletasi menggunakan pelarut etanol dan toluena perbandingan volume 1:1, 1:2, dan 2:1. Penentuan konsentrasi relatif kuinon, antrakuinon, dan tektokuinon dalam ekstrak menggunakan Pyrolisis-Gas Chromatography Mass Spectrometry (Pyr-GCMS).
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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