Judul: Kadar Lignin dan Delignifikasi Empat Jenis Kayu Eukaliptus.
Abstrak: Lignin content and its reactivity are known as an important characteristics of wood in relation to the pulping process, because it will affect the process easiness and pulp quality. The aim of the research was to measure lignin content and delignification of four Eucalyptus woods, which is widely used as raw material in pulp industry. Lignin content was determined as Klason lignin, acid soluble lignin, and total lignin, whereas delignification was expressed as solubility lignin in alkaline cooking. The result show that Klason lignin of four Eucalyptus woods were 25.14-36.65% and acid soluble lignin were 2.07-2.44%. Alkaline cooking at 150 °C for 90 min obtained solubility of lignin 18.54-31.60%. The variety of acid soluble lignin of four Eucalyptus woods was not big different, therefore delignification was influenced by Klason lignin.
Keyword: acid soluble lignin, delignification, Eucalyptus, lignin solubility, Klason lignin

Judul: Karakteristik Kimia Lignin Sepuluh Jenis Kayu.
Abstrak: Lignin is a chemical component of wood which was concerned in relation to pulping process. The content and reactivity of lignin affect the easiness of delignification in the pulping process. This research aimed to analyze the chemical characteristics of lignin in the ten wood species; which were expressed as total lignin, Klason lignin, acid-soluble lignin, and syringil/guiacyl ratio. Total lignin was defined as a sum of Klason and acid-soluble lignin. Lignin content varied widely between wood species. Klason lignin was 20.51-34.3% and acid-soluble lignin was 0.31-2.8%. Wood species having lower lignin content tend to have higher acid-soluble lignin and syringil/guaiacyl ratios. Consequently, there was clear and positive correlation between acid-soluble lignin and syringil/guaiacyl ratio (R2=0.92)
Keyword: acid soluble lignin, delignification, Klason lignin, monomers lignin, reactivity

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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