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: A Continuous Vaccination Strategy in the SVIR Epidemic Model
Abstrak: Vaccination is conducted to minimize the spread of a disease. The vaccination is usually done several times within a fixed time interval. In the SVIR model, it is assumed that individuals do not get immediate immunity following a vaccination program. So according to process of vaccination on SVIR model, there are two strategies, i.e. the continuous vaccination strategy (CVS) and the pulse vaccination strategy (PVS). In this study, only the CVS strategy in epidemic model SVIR is considered. Results of the study indicate that dynamics of the CVS system depends on the basic reproductive number. If the basic reproductive number is less than one, then the disease-free fixed point is asymptotically stable. It means that the disease will eventually disappear from the population. Conversely, if the basic reproductive number is greater than one, then the endemic fixed point is asymptotically stable, which means that the disease will remain exist in the population. Simulation result shows that the vaccination would minimize the spread of disease by reducing the basic reproductive number. If the time for the vaccinated recipients to obtain the immunity, as well as a possibility of vaccinated recipients to be infected are neglected, then the disease will be eradicated. This condition is called an over-evaluating effect of vaccination.
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