Judul: Durability and Wettability of Chemically Modified Scots Pine Wood (Pinus sylvestris L.) by Softener and Citric Acid-Sorbitol
Abstrak: Pinus scots (Pinus sylvestris L.) merupakan kayu yang banyak digunakan sebagai bahan baku produksi di benua Eropa, namun kayu ini memiliki sifat ketahanan yang rendah terhadap organisme perusak kayu. Modifikasi kimia menggunakan softener dan asam sitrat (2-hydroxy-1,2,3- propanetricarboxylic acid)-sorbitol (CAS) diaplikasikan untuk meningkatkan keawetan kayu. Penelitian ini bertujuan untuk menganalisis pengaruh modifikasi kimia menggunakan softener dan CAS (dengan berbagai rasio molar dan konsentrasi larutan) terhadap keawetan dan keterbasahan kayu pinus scots. Keawetan kayu terhadap rayap diuji melalui pengujian rayap kayu kering dan uji kubur. Pengujian karakteristik permukaan dilakukan sebelum dan sesudah uji kubur. Hasil penelitian menunjukkan bahwa modifikasi kimia mengunakan softener dan CAS meningkatkan ketahanan pinus scots terhadap rayap kayu kering dan rayap tanah. Peningkatan rasio molar dan konsentrasi asam sitrat meningkatkan keawetan kayu. Energi bebas permukaan (SFE) dan keterbasahan menurun setelah perlakuan modifikasi kimia menggunakan softener dan CAS. Kekasaran permukaan, SFE, dan keterbasahan meningkat setelah uji kubur., Scots pine (Pinus sylvestris L.) is a wood that widely used as a raw material in Europe, but this wood has low resistance against wood destroying organisms. Chemical modification by softener and citric acid (2-hydroxy-1,2,3-propanetricarboxylic acid)-sorbitol (CAS) was applied to increase the wood durability. This study aimed to analyze the effect of chemical modification by softener and CAS (with various molar ratios and solution concentrations) on the durability and wettability of scotspine wood. The durability of wood against termites was tested by dry-wood termite and grave yard testing. Surface characteristics testing was carried out before and after the graveyard test. The result shows that chemical modification by softener and CAS increased the resistance of scots pine against dry-wood and subterranean termites. The increasing of molar ratio and solution concentration increased the wood durability. The surface free energy (SFE) and wettability decreased after chemical modification treatments by softener and CAS. Surface roughness, SFE, and wettability increased after graveyard test.
Keyword: citric acid and sorbitol, durability, wettability, scots pine, softener, asam sitrat dan sorbitol, keawetan, keterbasahan, pinus scots, softener

Judul: Durability and Wettability of Modified Scots Pine Wood with DMDHEU (Dimethylol Dihydroxy Ethylene Urea) and Phenol Formaldehyde
Abstrak: Ketahanan kayu dapat ditingkatkan dengan modifikasi kimia menggunakan DMDHEU (1,3-dimetilol-4,5-dihidroksi etilen-urea) dan fenol formaldehida. Penelitian ini bertujuan menganalisis pengaruh modifikasi kimia (PF, PF dan bio oil (PFO), DMDHEU (D), DMDHEU termodifikasi (MD), DMDHEU bebas formaldehid (DE), dan DMDHEU dengan softener (DS)) terhadap keawetan kayu. Penelitian ini juga menganalisis pengaruh perlakuan modifikasi kimia terhadap karakteristik permukaan kayu scots pine sebelum dan setelah uji kubur. Modifikasi kayu menggunakan metode vakum tekan. Ketahanan kayu scots pine terhadap serangan rayap tanah dan rayap kayu kering meningkat setelah dimodifikasi dengan DMDHEU dan PF. Kehilangan berat tertinggi terdapat pada kayu kontrol dan terendah pada kayu PF. Kekasaran permukaan kayu termodifikasi kimia lebih tinggi dibandingkan kayu tanpa perlakuan. Energi bebas permukaan (SFE) dan keterbasahan kayu scots pine sebelum uji kubur pada perlakuan kontrol lebih rendah dibandingkan D, DE, dan MD, namun lebih tinggi dibandingkan DS, PF, dan PFO. Kekasaran permukaan, SFE, dan keterbasahan kayu scots pine meningkat setelah tiga bulan uji kubur., Wood resistance can be improved by chemical modification using DMDHEU (1,3-dimethylol-4,5-dihydroxy ethyleneurea) and phenol formaldehyde. This study aimed to analyze the effect of chemical modification (PF, PF with bio oil (PFO), DMDHEU (D), modified DMDHEU, DMDHEU derivative of formaldehyde-free resin (DE), and DMDHEU with softener (DS)) on durability of scots pine. The study also analyzed the effect of these chemical modification on the surface characteristics of scots pine wood before and after graveyard test. Wood was chemically modified by using vacuum press method. Scots pine resistance against ground termites and dry wood termites increased after modification with DMDHEU and phenol formaldehyde. The highest weight loss was found in the untreated wood and the lowest in PF treated wood. Surface roughness of chemically modified scots pine wood were higher than untreated wood. Surface free energy and wettability of untreated scots pine wood before graveyard test were higher than D, DE, MD treated wood but lower than DS, PF, and PFO treated wood. Surface roughness, surface free energy, and wettability increased after three months of graveyard test.
Keyword: DMDHEU, durability, PF, scots pine, surface characteristics

Judul: Dynamical System of Hepatitis B in Three Groups with Vaccination
Abstrak: The aim of this study is to modify the hepatitis B transmission model in three age groups involving vaccination from the model conducted by Zhoe and Zhang.The method used is to analyze the stability of the fixed point and its basic reproduction number (R_0). Performed stability analysis and numerical simulation to see population dynamics. Next, a sensitivity analysis of the parameters was carried out to see its effect on R_0. From the analysis obtained two fixed points, namely non-endemic and endemic fixed points. Non-endemic fixed points are locally asymptotically stable if R_0 <1 Meanwhile, the endemic fixed point is locally asymptotically stable if R_0 > 1. Hepatitis vaccination affects the number of susceptible population, because the more successful the vaccination, the smaller the number of susceptible populations so that the smaller the population will be infected.
Keyword: Dynamic, Hepatitis B, Vaccine, Mathematical model