Judul: Yellowfin Tuna (Thunnus albacares) Skin Collagen as Active Ingredients Candidate in Anti-aging Cream
Abstrak: Penambahan bubuk kolagen kulit ikan tuna sirip kuning (Thunnus albacares) sebagai kandidat bahan aktif dalam pembuatan krim anti-aging dapat berperan sebagai pelembab bagi kulit. Penelitian ini bertujuan menentukan karakteristik krim anti-aging serta konsentrasi kolagen kulit ikan tuna sirip kuning (T. albacares) terbaik sebagai kandidat bahan aktif pada sediaan krim anti-aging. Tahapan penelitian ini yaitu pembuatan sediaan krim anti-aging dan penentuan formula terbaik. Krim anti-aging diformulasikan dengan penambahan kolagen sebanyak 0%, 0,5%, dan 1% (b/b). Formulasi sediaan krim anti-aging terbaik didapati pada krim dengan penambahan kolagen larut pepsin kulit tuna sirip kuning dengan konsentrasi 0,5% (KA). Sediaan krim anti-aging terpilih telah sesuai dengan acuan yang ada. Sediaan krim KA (0,5% kolagen kulit tuna sirip kuning), memiliki rata-rata nilai sensori 7,06, nilai pH sebesar 7,53, daya sebar 7,05 cm, daya lekat 21,81 detik, viskositas 9650 ± 268,51 cP, dan kemampuan melembabkan kulit sebanyak 26,19%., The addition of yellowfin tuna (Thunnus albacares) skin collagen powder as active ingredients candidate in the production of anti-aging cream have a role as moisturizer agent for the skin. This study aimed to determine the anti-aging cream’s characteristics and the best concentration yellowfin tuna (T. albacares) skin collagen as active ingredients candidate for the anti-aging cream. This research phase involved making anti-aging cream preparations and determining the best formulation. Anti-aging cream formulated with 0%, 0,5%, and 1% collagen (w/w). The best anti-aging cream formulation found on cream with pepsin soluble collagen yellowfin tuna skin at concentration of 0,5% (KA). The selected anti-aging cream has followed the existing references. KA cream (0,5% yellowfin tuna skin collagen) had an average sensory value of 7,06, pH value of 7,53, spreadability about 7,05 cm, adhesion of 21,81 seconds, viscosity of 9650 ± 268,51 cP, and ability to moisturize the skin by 26,19%.
Keyword: formula, kolagen larut pepsin, kosmetik, krim, pelembab

Judul: Characterization of Face Serum Collagen Yellowfin Tuna (Thunnus albacares) Skin
Abstrak: Kulit tuna sirip kuning (Thunnus albacares) dapat diolah menjadi kolagen. Kolagen dimanfaatkan dalam pembuatan produk serum wajah. Penambahan kolagen dapat meningkatkan nilai fungsi serum wajah terhadap kulit. Serum merupakan sediaan kosmetik dengan bahan dasar yang bersifat minyak dan air, memiliki nilai viskositas yang rendah, memiliki sifat penyerapan yang cepat serta mudah meresap ke dalam lapisan kulit. Penelitian ini bertujuan menentukan konsentrasi kolagen kulit tuna sirip kuning (Thunnus albacares) terbaik dalam pembuatan serum wajah serta menentukan karakteristik produk serum wajah terpilih. Tahapan penelitian ini yaitu pembuatan sediaan serum dan penentuan formula terbaik. Sediaan serum diformulasikan dengan kolagen kulit tuna sirip kuning dengan konsentrasi 0%, 0,5% dan 1%. Produk sediaan serum yang terpilih yaitu serum kolagen 1% (SKK) dengan menggunakan metode perbandingan eksponensial. Sediaan serum SKK memiliki pH 6,74, daya lekat 18,01 detik, diameter daya sebar 9 cm, nilai viskositas 182 cPs, mampu meningkatkan nilai kelembaban sebesar 41,67% dan rata-rata nilai sensori 5,8 termasuk dalam kategori agak suka., Yellowfin tuna (T. albacares) skin can be processed into collagen. Collagen is used in the manufacture of facial serum products. The addition of collagen can increase the function value of facial serum on the skin. The serum is a cosmetic preparation with essential oil and water ingredients, has a low viscosity value, has fast absorption properties, and is easily absorbed into the skin layer. This study aims to determine the best concentration of yellowfin tuna (T. albacares) skin collagen in manufacturing facial serum and the characteristics of the selected facial serum product. This research stage involves making serum preparations and determining the best formula. Serum preparations were formulated with yellowfin tuna skin collagen with concentrations of 0%, 0,5%, and 1%. The selected serum product is serum collagen 1% (SKK) using the exponential comparison method. The preparation of SKK serum has a pH of 6.74, adhesion of 18.01 seconds, a diameter of spread 9 cm, viscosity value of 182 cPs, able to increase the humidity value by 41.67% and the average sensory value of 5.8 is included in the moderately good category.
Keyword: collagen, cosmetics, moisture, serum, yellowfin tuna skin

Judul: Bifurkasi Hopf pada siklus bisnis IS-LM tanpa dan dengan waktu tunda
Abstrak: One of business cycle models in dynamical economics is the IS-LM business cycle model with time delay, where the time delay lies in stock capital variables. It is a time delay between the existence of stock capital and the time to get ready to invest. In a model without time delay, changing the parameter of investment rate on income could affect the system stability. On the other hand, in a model with time delay, there exists critical time delay changing the system stability. This shows limit cycle, which can be concluded that Hopf bifurcation occurs
Keyword: Bogor Agricultural University (IPB), time delay, Hopf bifurcation, business cycle model