Judul: Pengaruh Penambahan Minyak Nilam sebagai Fiksatif terhadap Ketahanan Wangi Gel Pengharum Ruangan Alami.
Abstrak: Conventional gel air freshener mostly contains sinthetic materials, especially fragrance and fixative agent, which potentially harms human health and the environment. Therefore, it is necessary to develop product that more friendly to the environment and save for human by using natural essential oil. This natural gel air freshener scents in a short periode if its used in high room temperature. So, as natural fixativea agent, patchouly oil is added in this research. Patchouly oil has a high boiling point and specific aroma. The purpose of this study are to determine suitable gel formula by hedonic test, the weight loss of the product during four weeks, concentration of patchouly oil which results in the best aroma resistance and its effectiveness as fixative agent in gel based air freshener by comparison pairwise test. The results showed that the best gel formula is contains of 3% of carrageenan, 1% of agar-agar, and 1% of glucomannan. Product containing 0% of patchouly oil and 8,9% of lemon oil showed the most prefered colour and the most prefered aroma. The lowest product weight loss is 57,44%, which is resulted from the addition of 1,1% of patchouli oil to 8,9% of lemon oil. The best aroma retention is resulted from the addition of 1,1% of patchouli oil to 8,9 % of lemon oil. The most effective concentration of patchouli oil in binding the gel air freshener aroma is 1,1%.
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Judul: Application of essential oils in  insect repellent air freshner gel
Abstrak: Citronella and lavender oils are known as insect repellent. Composition of insect repellent, combined with aromatic fragrance, such as lemon, kaffir lime, and ylang-ylang oils were packed in an air freshner gel with the addition of patchouli oil as fixative agent. The purposes of this study are (1) to get the best concentration of patchouli oil as fixative agent; (2) to get the best composition of insect repellent active ingredients and fragrance materials, and (3) to know the resistance and the loss on fragrance odor in air freshner gel during use (fourteen days). The methods used are sensory test with skoring test, effectiveness test of the air freshner gel for repelling mosquito, and hedonic test. Then, the last methods used are sensory test and weighing. The research result show that the best concentration of patchouli oil as fixative agent is 1% patchouli oil. The next results, there are three best compositions of essential oils in air freshner gel formula that effectively repell insects. The first formula composition consist fragrance ingredient (lemon oil 2%) and the active ingredient of insect repellent (citronella oil 2% and lavender oil 2%). The second formula composition comprises fragrance material (kaffir lime oil 2%) and the active ingredient of insect repellent (citronella oil 3%). The third formula composition consisting of fragrance material (ylang-ylang oil 2%) and the active ingredient of insect repellent (citronella oil 2% and lavender oil 2%). Based on the result of hedonic test, the most preffered fragrance from the three formulas is formula with lemon fragrance. The last results, the resistance on fragrance odor can be estimated that is still acceptable until eight days of use and the loss on fragrance odor during use (fourteen days) can be estimated 54.89% (0.988 gram).
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Judul: Invers dari Matriks Tridiagonal Jacobi
Abstrak: Suatu matriks berukuran n×n dinamakan matriks tridiagonal jika untuk . Karya ilmiah ini memberikan algoritma yang mudah untuk menemukan invers ( dari matriks tridiagonal Jacobi yang simetrik dan nonsimetrik. Setiap elemen pada matriks tridiagonal ini adalah bilangan real. Terdapat 3 lema dan 2 teorema untuk menentukan . Lema pertama menunjukkan persamaan utama dalam membuktikan lema-lema dan teorema-teorema selanjutnya. Invers dari matriks yang simetrik dibuktikan oleh lema kedua yang menunjukkan elemen-elemen baris ke- dari . Selanjutnya, lema kedua dilengkapi dengan teorema pertama yang menunjukkan elemen-elemen dengan . Invers dari matriks yang nonsimetrik dibuktikan oleh lema ketiga yang menunjukkan elemen-elemen dengan dan elemen-elemen dengan dibuktikankan oleh teorema kedua.
Keyword: symmetric, nonsymmetric, matrix