Judul: Improving sardines (Sardinella sp.) oil quality using centrifugation and synthetic adsorbent
Abstrak: Sardines (Sardinella sp.) was a by-product of flouring and canning industry where sardines are known contain more than 10% fat and most of the fat that was stored in the belly cavity (Moeljanto 2010). Purification is needed to get fish oil with food quality, so it is safe to be consumed. The purpose of this research were (1) characterize and determine the best fish oil taken from different locations; (2) determine the best purification treatment of centrifugation, adding synthetic adsorbent and combination; (3) determine optimization treatment of centrifugation and adding synthetic adsorbent using response surface method (RSM). Fish oil taken from different locations, Banyuwangi and Pekalongan. The best fish oil was taken from Pekalongan with composition of an unsaturated fatty acid 40.17% and saturated fatty acid 31.16%, with free fatty acids value 3.94 %, peroxide value 5 meq/kg, anisidin value 0.88 meq/kg and totox value 10.88 meq/kg. Purification by centrifugation best treatment was 10,500 rpm for 30 minutes. Purification by adsorbent synthetic best treatment was adding atapulgite 3% and bentonite 3%. Purification by combination centrifugation and adding synthetic adsorbent best treatment was centrifugation at 10,500 rpm for 30 minutes combined atapulgite 3% and bentonite 3%. The response surface method optimization best treatment was centrifugation at 9,494.89 rpm for 31.48 minute combined atapulgite 3% and bentonite 3% with free fatty acids value 4.07%, peroxide value 2.97 meq/kg, anisidin value 0.81 meq/kg and total oxidation value 6.32 meq/kg. An increase in percent of fish oil light transmission at different wave lengths by centrifugation and adding synthetic adsorbent. The best transmission values obtained at the combination synthetic adsorbent of bentonite and atapulgite on fish oil which is centrifuged first with 10,500 rpm for 30 minutes.
Keyword: adsorbent, centrifugation, fish oil, response surface method, Sardinella sp.

Judul: Peningkatan Kualitas Minyak Ikan Sardin (Sardinella sp.) dengan Adsorben Alami
Abstrak: Fish oil as by product of sardine canning process was a potential source of ω-3 fatty acids. One method of improving the quality of sardine fish oil is by purification using adsorbens. Type of the adsorben which used in this research was natural adsorbens, such as chitosan, fish scales, and eggshells. The purpose of this study was to determine the quality of fish oil before and after addition of natural adsorben. Several fish oil analysis which used were gas chomatography (GC), free fatty acids (FFA), acid value (AV), and peroxide value (PV). The result of GC showed that ω-3 is the highest fatty acids content in fish oil, which is EPA 13,31% and DHA 11,99%. Then, after addition of natural adsorbens, quality of sardine fish oil was improved. The result showed FFA, AV, PV levels decreased. The best natural adsoben to decrease FFA and AV levels is eggshells 3% which can reduce FFA levels by 35,82% and AV by 36,10%. In the peroxide analysis, the best treatment is the addition of fish scales and eggshells 7% which can reduce AV levels by (21-23)%. FFA and AV levels of fish oil still on International Fish Oil standards (IFOS), whereas the PV levels is exceed from standards.
Keyword: PV, AV, FFA, fatty acid, natural adsorben, fish oil

Judul: igenvalues and Eigenvectors of Tridiagonal Matrix with Non Constant and Recurrent Diagonal Entries.
Abstrak: Matriks tridiagonal adalah suatu matriks yang mempunyai entri-entri bernilai nol kecuali pada diagonal utama, di bawah diagonal utama (subdiagonal) dan di atas diagonal utama (superdiagonal). Entri pada diagonal utama tidak konstan dan berulang. Setiap entri pada matriks tridiagonal ini adalah bilangan kompleks. Dalam karya ilmiah ini, akan dibuktikan 3 teorema untuk menentukan nilai eigen dengan 2 kasus dan 1 teorema untuk menentukan vektor eigen. Teorema pertama menentukan polinomial karakteristik dari matriks tridiagonal. Polinomial karakteristik dari matriks tridiagonal tersebut digunakan untuk menentukan nilai eigen pada teorema kedua dan ketiga serta menentukan vektor eigen pada teorema keempat
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