Judul: Pengaruh penggunaan bahan pengokdidasi terhadap mutu kulit samoa pada penyamakan  kulit menggunakan minyak biji karet
Abstrak: Leather tanning using oil as the tanning agent has disadvantages, such as the time of oxidation which is takes a long time in about 9 days. Using sodium percarbonate as oxidizing agent in the tanning process, known to shorten the time into two days, eventhough, the high cost of sodium percarbonate was being obstacle in its use. Other oxidizing agents such as hydrogen peroxide and sodium hypochlorite may have the same function with sodium percarbonate, i.e. acceleration of the oxidation process. The objectives of this research were to investigate the influence of the oxidizing agents and their concentrations on the quality of chamois leather and to determine the best combination of type and concentration of oxidizing agents in the production process of chamois leather. The main research consisted of leather tanning using rubber seed oil, oxidation in drum with three types and concentrations of the oxidizing agents, measurements of physical, chemical and organoleptic properties of chamois leather. The results showed that the three types of the oxidizing agent could be used to accelerate the oxidation process in the manufacture of chamois leather. The type of oxidizing agent gave significant effect on shrinkage temperature, ash content, colour and odour of leather, while the oxidizing agent concentration significantly affected the colour and odour of chamois leather. The treatment of experiment selected based on the quality of leather was sodium hypochlorite with the concentration of 2%. Tanning by using this treatment produced chamois leather with the properties as follows: shrinkage temperature of 75.2oC, tensile strength of 30.5 N/mm2, elongation at break of 134.3%, tear strength of 86.2 N/mm, water absorption of 265% (2 hours) and 286% (24 hours), pH 6.56, oil content of 8.71%, ash content of 1.12%, softness of 8-9, colour of 7-8 and odour
Keyword: Hydraulic pressing, Oxidizing agent, Sanitizer

Judul: Pengaruh Konsentrasi Natrium Perkarbonat dan Jumlah Air Terhadap Mutu Kulit Samoa Pada Penyamakan Kulit Dengan Minyak Biji Karet.
Abstrak: Chamois leather is a popular product in trading, because it has specific uses. Nowadays, chamois leather is produced with fish oil as a main oil tanning agent. The problem are odors and colour of the product as well as the expensiveness of the fish oil. To overcome the problem, subtitution of the fish oil with vegetable oil, such as rubber seed oil. May be carried out other problem is oxidation needs a long time, such as about 2 weeks. This causes production process of tanning leathers tanning chamois needs long time. The objectives of this research were to understand the effect of amounts of sodium percarbonate and water in chamois leather tanning using rubber seed oil on the quality of the chamois leather. Besides that, this research also aimed to get the best combination of the factors. The preliminary research was carried out by analyzing the physico-chemical properties of rubber seeds oil. The main research was done by tanning of sort skin pickeld pelt. In its oxidation, combination of 2%, 4%, and 6 % of sodium perkarbonat and 70%, 50% dan 30% of water were used. The experimental design used was completely random factorial design. The results of preliminary research were rubber seed consisted of 49% shell and 51% endosperm. The characteristics of the rubber seed oil were density of 0.94 (g/cm3), viscosity of 48.4 centistokes, colour of 2713 PtCo units, acid value of 15.2 mg KOH/g oil , FFA of 5.82 %, iodine number of 113 g iodine/ 100 g oil, saponification value of 350.06 mg KOH/g oil, and peroxide number of 24.13 miliekuivalen/1000 g oil. The main research show that sodium percarbonate amount significantly affected thickness and oil content; amount of water significantly affected oil content of the leather; The interaction between sodium percarbonate and water significantly affected ash content and oil content. The optimum conditions for the oxidation were amount of sodium percarbonate of 4% and water at 50%. The physical properties of the leather were shrinkage temperature of 71oC, thickness of 0.87 mm, tensile strength of 35.95 N/mm2, elongation of 129%, tear strength of 82.01 N/mm, water absorption of 226% (2 hours) and 303% (24 hours). The chemical properties were pH of 7.45, oil content of 8.1% and ash contain of 1.3%. The organoleptic properties were softness of 6 – 7, colour of 7 - 8, and odour of 7 – 8.
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Judul: Analisis Model Pandemik dan Prepandemik Avian Influenza pada Populasi Manusia
Abstrak: Avian influenza is a viral disease caused by a virus within the subtype of H5N1 in which its transmission caused by birds or human. In human population, transmission process of avian influenza is discussed in the model called: bird model, prepandemic model and pandemic model. The bird model has two equlibrium points. These are saddle disease free equilibrium and stable endemic equilibrium. The endemic equlibrium occurred when the reproduction number of avian influenza is greater than one. In the endemic equilibrium, avian influenza may infect both bird and human. The prepandemic model has two equilibrium points. These are avian influenza dominant equilibrium and human influenza dominant equilibrium. The human influenza dominant equilibrium occurred when the reproduction number of human influenza is greater than one. The pandemic model has one pandemic equlibrium. The human influenza pandemic occurred when the ratio of human influenza invasion, pandemic invasion and the reproduction number of human influenza is greater than one, respectively. The avian influenza pandemic occurred when the ratio of human influenza invasion, pandemic invasion is less than one and the reproduction number of avian influenza greater than one, respectively.
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