Judul: Karakteristik Papan Partikel Fungsional Sabut Kelapa Dengan Penambahan Arang Aktif Sebagai Penjerap Gelombang Elektromagnetik
Abstrak: Particle board is a substitute material that can meet national wood needs. Indonesia, a country with the largest coconut plantations, has abundant coconut coir waste which has not been utilized optimally. As the lignocellulose-containing material, coconut coir can potentially be processed into particle board. Due to technological developments, particle board is not only used for construction but also has additional functions. The objective of the research is to determine the physical and mechanical properties of coconut coir particle board and the effect of adding activated charcoal to partcile board in absorbing electromagnetic wave radiation. Activation of coconut coir-activated charcoal was carried out at a temperature of 750 oC by comparing two activators, namely H3PO4 10% and KOH 10%. The activation process took place for 60, 90 and 120 minutes. The best activated charcoal would be used as a particle board mixture. Particle board was made with three factors, namely particle size, board thickness and amount of adhesive. The particle sizes used were coarse (passed 40 mesh, retain 60 mesh) and fine (passed 60 mesh, retain 80 mesh). The thickness treatment used a thickness of 0.5 and 1 cm while the amount of adhesive used a concentration of 0, 5 and 10%. The board's production used a hot press at a temperature of 170 oC for 20 minutes. Based on physical and mechanical properties testing, the best particle board was produced from the coarse particle size treatment (40 mesh passed, 60 mesh retained), 0.5 cm board thickness and 5% adhesive content. The best activated charcoal was then added to the particle board with the amount of 0, 5, 10, 15 and 20%. Based on the physical and mechanical test results, functional particle board does not meet the standards. However, the addition of 15% activated charcoal to the particle board was able to absorb electromagnetic waves by 74.88%. This best adsorption produces a reflection loss value of -12 dB at a frequency of 10.53 GHz.
Keyword: activated carbon, adsorption, coconut coir, electromagnetic wave, particle board

Judul: Karakteristik Papan Partikel Tanpa Perekat dari Serat Sabut Kelapa dengan Perlakuan Oksidasi, Penambahan Parafin dan Waktu Kempa
Abstrak: Manufacture of binderless particleboard from coconut fiber research was done as an effort to use alternatives raw materials in timber industry which has become limited and to reduce adhesives synthetic that has pollute the environment such as urea formaldehyde (UF). Paraffin was expected to make the physical properties of particleboard better. The purpose of this research was to know the characteristics of binderless particleboard from coconut fiber based on particleboard standard JIS A 5908:2003 and determine the influence of oxidation treatment, additional paraffin and time of pressing on the characteristics of particleboard. Oxidation method was done by spraying hydrogen peroxide (15%) and ferrosulfate (7.5%), 10 minutes of pressing and 20 minutes at temperature 180 ºC with a pressure of 25 kgf/cm2. The results: density (0.44-0.56 g/cm3), moisture content (5.94-10.08%), all treatment met the standards. The results of strong hold spanner (19-80 kgf): only combination of oxidation treatment that met the standards. The result of thickness swelling: only combination of oxidation treatment, paraffin 0.5% and without paraffin with 20 minutes of pressing (8% and 12%) met the standards. In conclusion for all the treatment, the one that didn’t meet JIS standard: Internal Bond (IB), Modulus of Elasticity (MOE) and Modulus of Rupture (MOR).
Keyword: pressing time, particleboard, paraffin, oxidation, JIS A5908:2003, coconut fiber

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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