Judul: Studi Toksisitas Nikel (Ni) terhadap Konsumsi Oksigen, Kondisi Hematologi, Histopatologi dan Stres Sekunder Juvenil Ikan Bandeng Chanos chanos [Forsskal]
Abstrak: Nikel merupakan salah satu jenis logam berat yang memiliki sifat toksik. Logam berat nikel dapat meracuni darah, menganggu sistem pernapasan, merusak jaringan, selaput lendir, dan mengubah sistem sel. Kegagalan produksi budidaya ikan pada perairan sekitar industri pertambangan nikel berpotensi disebabkan oleh nikel. Hal ini dimungkinkan dengan peningkatan kekeruhan pada perairan pesisir di lokasi pertambangan nikel. Perairan pesisir dengan potensi kandungan logam berat nikelnya pada akhirnya masuk ke petakan tambak ikan bandeng bersamaan dengan pasang air laut atau melalui pemompaan. Penelitian ini bertujuan untuk mengetahui potensi toksisitas akut nikel yang diekspresikan oleh nilai LC50 nikel dan mengkaji pengaruh toksisitas nikel terhadap tingkat konsumsi oksigen, kondisi hematologi, histopatologi dan stres sekunder juvenil ikan bandeng. Penelitian ini dilaksanakan atas tiga tahap, yaitu: uji nilai kisaran, uji akut, dan uji sub-kronik. Ikan uji yang digunakan adalah ikan bandeng ukuran 6-7 cm, sedangkan logam berat nikel yang digunakan sebagai sumber toksikan dalam penelitian adalah nikel klorida (NiCl2 Hasil penelitian menunjukkan bahwa nikel memiliki sifat toksik yang tinggi terhadap juvenil ikan bandeng dengan nilai LC). Wadah penelitian berupa akuarium berukuran 20 x 20 x 30 cm, yang diisi air laut dengan salinitas 15 ‰ sebanyak 10 liter. Analisis kadar nikel pada media percobaan menggunakan Atomic Absorption Spectroscopy (AAS). Pada uji akut, digunakan 5 taraf konsentrasi yaitu tanpa nikel (A); 8,89 ppm (B); 15,81 ppm (C); 28,12 ppm (D) dan 50,01 ppm (E). Selanjutnya pada uji sub-kronis, digunakan 5 taraf konsentrasi yaitu 0 ppm; 0,12 ppm; 0,59 ppm; 1,19 ppm dan 3,56 ppm.
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Judul: Toksisitas nikel [ni] terhadap ikan nila gift (Oreochromis niloticus) pada media berkesadahan lunak (soft hardnes)
Abstrak: Nickel is a member of heavy metals. It can potentially poison the blood, interfere the respiratory system, damage tissues and membranes of lenders, and change the cell system. This research aimed to determine the effect of nickel toxicity on various biochemical processes in body GIFT tilaphia such as : level of oxygen consumption, hematological system, histopathology system, level of nickel accumulation,growth rate, and on survival rate. This research was conducted in three stages: test value range, acute test, and sub-chronic test. Acute test consisted of 5 treatment concentrations (0.00, 10.67, 18.98, 33.76, and 60.05 ppm). Sub-chronic test consisted of 3 phases (0.00, 1.39, and 4.18 ppm). Lc-50 value of 96 hours was 13.93 ppm. The level of nickel accumulations in flesh on treatment with concentrations of 60.05, 33.76, 18.98, 10.67, and 00:00 ppm respectively were: 73.37, 56.08, 42.00, and 32.90 mg/kg, while at 0:00 ppm, nickel was not detected. Generally, level of oxygen consumption in chronic sub test decreased significantly. After 32 days nickel exposure, treatment with concentration 4,18 and 1,39 ppm was respectively down: 0,47 to 0,14, and 0,46 to 0,21. At 0,00 ppm, it also decreased level of oxygen consumption but it was still stable relatively, from 0,49 to 0,42. Nickel exposure for 30 days also decreased hematocrit level, hemoglobin, erythrocyte, increased number of leukocytes, reduced growth rate, and damaged gill and liver
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Judul: Query Expansion based on Bilingual Dictionary Using Conditional Probability
Abstrak: Query expansion is a technique that can be used to bridge vocabulary gaps between queries and documents in the collection. With query expansion, user will be helped to formulate queries well so that user will optimize the search result. In this study, the expansion term was resulted from the translation of bilingual dictionary. Subsequently, several terms of expansion were elected based on the closeness of its relationship with the original query. This research showed that conditional probability can be used to select expansion term in bilingual translation method query expansion. The result of 1000 documents was more than 97% relevan document can be retrieved by this system. The more expansion term used, the larger number relevan document was retrieved.
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