Judul: Kajian Pemanfaatan Getah Pinus (Pinus merkusii) Sebagai Bahan Baku Perekat
Abstrak: Pine merkusii included to multipurpose tree species that developed and expanded continually to produce timber, gums, and as conservation land. Almost all parts of the tree can be utilized. Part of the tree that has high values is the pine gum. Processing of pine resin is widely used in printing ink industry, coating industry, and adhesive industry. Adhesive substance is a material that can be joined with the same or different type of object through bonding process or surface contact, so the body of joint object is resist to separation effort. In the production of pine gum adhesive substance, esterification process carried out to improve the adhesive power. This research aims to study the process of making adhesive substance from pine gum esters, and also to determine the effect of acid number, ester number, glycerol number and catalyst concentration on adhesive strength of the adhesive products. Stages of this research is the characterization of pine gum raw materials; esterification using KOH catalyst with concentration 1.5 and 10% by weight of pine gum, and moles of glycerol 1.1, 1.5, and 2 mol; making of the adhesive substance and determination of the best adhesive substance based on its best adhesive strength. Conducted preliminary research is the characterization of raw materials of pine gum, and then continued with the main research that is esterification of pine gum using alkaline catalyst (KOH), and making of the adhesive substance of the pine gum esterification. The treatment that used is the concentration of KOH catalyst (1%, 5%, and 10%) and the mole of glycerol (1.1 mol, 1.5 mol, and 2 mol). The esterification results of the pine gum tested through acids numbers, esters numbers, and free glycerol levels by comparing between the unwashed pine gum esters and the washed. The esterification results are made into adhesive substance. Then the surface area of adhesive strength and the adhesive strength of adhesive substance tested with shear stress (shear strength) of the adhesive strength and test. Based on preliminary research results, the characteristics of pine gum that was obtained is a liquid, slightly yellow color, soluble in ethanol solvent ratio of 90 percent with 1 ml of pine resin:1 ml of ethanol, acid number 125.66, and viscosity Cp 8693.14. The results of measurements showed that the adhesive substance with the code C22 (with KOH catalyst 5%, 1.5 mol glycerol, washed) gives a better adhesive strength. The characteristics of adhesive substance with the code C22 are: acids numbers 109.21 and esters numbers 21:18. Based on the observations, it can be concluded that the adhesive substance that was processed with 5% catalyst and 1.5 mole of glycerol with the code C22 is the best adhesive substance compared with others based on its adhesive strength.
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Judul: Physical and Mechanical Properties of Chemical and Thermally Modified Pinus merkusii
Abstrak: Kayu Pinus merkusii memiliki ketahanan yang rendah terhadap faktor-faktor perusak menyebabkan kayu memiliki tingkat pemanfaatan yang kurang optimal. Peningkatan kualitas perlu dilakukan untuk memperpanjang masa pakai kayu, mempertahankan nilai fungsionalitas dan estetikanya. Peningkatan kualitas kayu dapat dilakukan dengan modifikasi kimia dan panas. Penelitian ini bertujuan untuk mengetahui dan menentukan sifat fisis dan mekanis kayu pinus pada segmen empulur ke kulit. Uji fisis yang dilakukan berupa kadar air, kerapatan, retensi, weight percent gain (WPG), stabilitas dimensi, dan penentuan sifat mekanis dengan static bending test. Modifikasi kimia dilakukan dengan impregnasi menggunakan campuran gliserol dan asam sitrat konsentrasi 40% dengan tekanan 7 bar selama 2 hari. Modifikasi panas dilakukan pada suhu 150? selama 6 jam setelah impregnasi. Percobaan menghasilkan kadar air 4,61-7,33%, kerapatan 0,5-0,73 g/cm3, retensi 26,7-35,58%, WPG 4,54-12,6%, ASE mencapai 89%, serta peningkatan MOE 20%, dan MOR 24%. Modifikasi kayu melalui impregnasi dan perlakuan panas dengan gliserol dan asam sitrat dapat meningkatkan stabilitas dimensi, meningkatkan kerapatan kayu serta sifat mekanis, maka dari itu metode modifikasi dengan bahan tersebut dapat menjadi solusi untuk peningkatan kualitas kayu dengan prinsip ramah lingkungan., Pinus merkusii wood has low resistance to wood-degrading factors, resulting in suboptimal utilization. Improving wood quality is necessary to extend its lifespan and maintain functional and aesthetic value. Quality enhancement can be achieved through chemical and thermal modification. This study aims to determine the physical and mechanical properties of Pinus merkusii wood from the pith-to-bark segment. Physical tests include moisture content, density, retention, weight percent gain (WPG), dimensional stability, and mechanical properties determined through static bending tests. Chemical modification involves impregnation using a 40% glycerol and citric acid mixture at 7 bar pressure for 2 days. Heat modification occurs at 150°C for 6 hours after impregnation. The experiments resulted in moisture content ranging from 4,61-7,33%, density from 0,5-0,73 g/cm³, retention from 26,7-35,58%, WPG from 4,54-12,6%, anti-swelling efficiency (ASE) reaching 89%, and increased modulus of elasticity (MOE) by 20% and modulus of rupture (MOR) by 24%. Wood modification through glycerol and citric acid impregnation and thermal treatment can enhance dimensional stability, increase wood density, and improve mechanical properties. Therefore, this environmentally friendly modification method holds promise for enhancing wood quality
Keyword: glycerol, citric acid, dimensional stability, retention, UTM test, WPG

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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