Judul: Study on the extraction of steroid from sandfish (Holothuria scabra) as natural testosterone
Abstrak: Sandfish has a potency as a source of the steroid hormones. The research aimed to study the extraction methods (conventional methods : maceration, soxhlet and refluxs) and Supercritical Fluids Extraction(SFE) in order to find the best method of testosterone extraction. The study used experimental design and descriptive analysis. Solvent selected for sandfish extraction consists of acetone, methanol, methanol: chloroform (1:2 v/v) and chloroform. The material solvent ratio was 1:1, 1:2 and 1:3 w/v, respectively.
Keyword: Supercritical Fluids Extraction, qualitative analysis, quantitative analysis, the purity of testosterone, West Java

Judul: Isolation, Characterisation and Biological Activity Test of Sea Cucumber Steroid Compound as Natural Aphrodisiac
Abstrak: Sea cucumber (Holothurian) is one of fisheries commodities which has a high economic value. Generally sea cucumber is traded in the dried form (bechede- mer). Bioactive of sea cucumber, commonly known as holothurin, has drawn attention because of its wide spectrum of biological effects namely antibacterial, antifungal, cytotoxic, haemolytic and anti-inflammation. One of holothurins, steroid compounds, as natural aphrodisiac have not been observed yet. Therefore, the aims of this study were (1) to isolate steroid compounds of sea cucumber and their contents, (2) to characterise the compounds, (3) to know biological activity of the compounds as aphrodisiac, and (4) to do experiment of nanofiltration membrane for initial purification of steroid compounds. Steroid compounds of Holothuria scabra have been originally isolated from Holothurian of Lampung waters using acetone as a solvent. Six steroid fractions were found through thin layer chromatography (TLC) and two fractions have been identified as cholesterol and testosterone with Rf 0.96 and 0.91, respectively. Initial purification used ceramic membrane with MWCO 1000 dalton for filtration process. To better understand biological activity of the steroid, day old chicken (DOC) was used as a test organism. Parameters observed were N absorption, body weight and cap, testes, cholesterol and testosterone concentrations of blood serum. The results clearly demonstrated that sea cucumber Holothuria scabra could be used as a source of aphrodisiac.
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Judul: Closed Knight’s Tour pada Papan Catur Berbentuk Persegi Panjang dengan Ukuran Maksimal 8 × 8
Abstrak: Closed Knight’s Tour merupakan langkah kuda yang mengunjungi setiap kotak pada papan catur tepat satu kali dengan langkah kuda berawal dan berakhir pada kotak yang sama. Graf yang terbentuk dari closed knight’s tour dinotasikan sebagai graf G(m,n), dengan m adalah banyaknya baris dan n adalah banyaknya kolom. Graf tersebut memuat Hamiltonian cycle. Sebuah graf terhubung G adalah graf bipartite jika dan hanya jika graf tersebut tidak memiliki cycle dengan panjang ganjil. Papan catur yang memenuhi syarat cukup untuk memiliki closed knight’s tour adalah papan catur berukuran 5 × 6, 5 × 8, 6 × 6, 6 × 7, 6 × 8, 7 × 8, dan 8 × 8.
Keyword: bipartite, closed knight’s tour, hamiltonian cycle, knight’s tour, teori graf