Judul: Chemical and Physical Properties of Melinjo Reaction Wood (Gnetum gnemon Linn.)
Abstrak: Kayu reaksi terbentuk selama pertumbuhan pohon yang ditandai dengan riap tumbuh yang lebih lebar dengan empulur yang tidak tepat berada di pusat lingkaran batang. Kayu reaksi pada jenis kayu daun jarum dan kayu daun lebar dapat berbeda dengan kayu normal dalam sifat kimia, fisis, dan mekanis kayu. Pohon Melinjo (Gnetum gnemon Linn.) adalah tanaman berbiji terbuka (Gymnospermae), tetapi memiliki beberapa sifat yang menyerupai kayu dari Angiospermae. Tujuan penelitian ini adalah untuk menguji kadar komponen kimia, proksimat, dan sifat fisis kayu reaksi melinjo (posisi kayu reaksi dan kayu samping) dibandingkan dengan kayu oposit (kayu normal). Sifat kimia kayu reaksi yang terbentuk pada kayu melinjo ini menyerupai kayu reaksi tekan dengan kadar lignin lebih tinggi dan kadar selulosa lebih rendah dibandingkan dengan kayu oposit. Sifat proksimat kayu melinjo memiliki keragaman relatif kecil. Nilai kalor sampel kayu melinjo berkisar 4060-4167 kkal/kg, dan nilai kalor tertinggi dihasilkan dari bagian kayu samping yang sejalan dengan tingginya kadar lignin dan karbon terikat dengan kadar zat terbang hampir sama. Kerapatan dan berat jenis kayu pada bagian kayu reaksi, kayu samping dan kayu oposit hampir sama sebagai akibat kecilnya keragaman kadar komponen kimia pada ketiga bagian kayu tersebut., Reaction wood is formed during tree growth which is characterized by wider increments with the pith not centered in the center of the stem circle. The reaction wood formed in the softwood is different from the broad leaved. Furthermore, it can differ from normal wood in chemical, physical, and mechanical properties of wood. Melinjo tree (Gnetum gnemon Linn.) is categorized as an open seeded plant (Gymnospermae) but melinjo wood has several properties that resemble from Angiospermae. The purpose of this study was to examine the chemical components, physical properties, and to analyzed the proximate of melinjo reaction wood (position of reaction wood and side wood) compared to opposite wood (normal wood). The chemical properties of the reaction wood formed on melinjo wood resembles that of tension reaction wood with higher lignin content and lower cellulose content compared to opposite wood. The proximate analysis of melinjo wood has a relatively small diversity. The calorific value of the melinjo wood samples ranged from 4060-4167 kkal/kg, and the highest calorific value was produced from the side wood which was in line with the high content of lignin and fixed carbon with almost the same volatile matter content. The density and specific gravity of the reaction wood, side wood and opposite wood were almost the same as a result of the small variation in the levels of chemical components in the three wood sections.
Keyword: proximate analysis melinjo, reaction wood, chemical components, physical properties

Judul: Sifat Kimia dan Proksimat Kulit Kayu Reaksi Tekan Pinus
Abstrak: Pembentukan kayu reaksi selama pertumbuhan pohon akan mengakibatkan perubahan sifat anatomi dan kimia kayu. Hasil penelitian sebelumnya menunjukkan bahwa pembentukan kayu reaksi juga menyebabkan perubahan sifat anatomi pada bagian kulit kayu, dan diduga akan menyebabkan perubahan kadar komponen kimianya. Penelitian ini bertujuan untuk menganalisis perbedaan kadar komponen kimia kulit kayu pada bagian kayu reaksi dan kayu oposit serta menguji karakteristik kulit kayu sebagai bahan baku energi biomassa melalui uji proksimat. Kadar komponen kimia kulit kayu diuji mengacu pada standar TAPPI dan analisis proksimat berdasarkan standar ASTM. Hasil penelitian menunjukan kadar lignin dan hemiselulosa pada kulit kayu bagian kayu reaksi lebih tinggi dibandingkan dengan kulit kayu bagian oposit, sedangkan kadar selulosa dan holoselulosa lebih rendah pada kulit kayu bagian reaksi dibandingkan dengan kulit kayu oposit. Berdasarkan hasil analisis proksimat, karakteristik kulit kayu bagian kayu reaksi lebih baik dibandingkan dengan kulit dari bagian opositnya, tetapi keduanya memiliki kualitas baik sebagai sumber energi biomassa.
Keyword: kayu reaksi, kayu tekan, komponen kimia, kulit kayu, analisis proksimat

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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