Judul: Depuration of Lead (Pb) from Nirwana Tilapia (Oreochromis niloticus) Using Coconut Cake and Palm Oil Cake Substituted Feed
Abstrak: Nirwana Tilapia is not only a popular fish for consumption in Indonesia but also an important aquaculture species. Nirwana is widely cultivated in locations with different water characteristics that can make the fish contaminated by various toxic and hazardous substances, including lead (Pb). Fish have the ability to absorb and accumulate Pb from the water in their body tissues, especially the tissues of the body that contains a lot of fat and muscle tissue such as the organs of the viscera. The process of absorption and accumulation is a mechanism that is unique and different for each fish species with the level of concentration which is linear with time. The Pb compound that accumulates can bring an effect which is lethal, sub-lethal and chronic to cultured fish and may experience biomagnifications in the food chain and will have an impact on human. Therefore, it is necessary to carry out post-fish harvest treatment of the cultured fish to clean up or reduce the concentration of Pb. The cleaning up or Pb reduction of fish can be done by depuration. The depuration method used in this research was by providing coconut cake and palm oil cake as substituted feed which have the ability to absorb Pb from the body tissues of fish since coconut cake and palm oil cake are actually vegetable materials that generally have coarse fiber and high fat. The coarse fiber in the diet is needed to assist in the digestion of food. The fat in the feed is expected to absorb large amounts of heavy metals deposited in the body tissues of fish. This study aimed to analyze the potential of coconut cake and palm oil cake for Pb depuration of nirwana. The research result would be benefitial information for farmers and the community of tilapia fishery, especially on the use of local products as alternative feed ingredients to improve food security through depuration mechanism. The treatments in this study were 100% commercial feed (Pk), 30% coconut cake + 70% commercial feed (PBB) and 30% palm oil cake + 70% commercial feed (PBS). The nirwana tilapia used with a weight of 100 ± 15 g. 10 fish were put in each plastic drum container corresponding with the number of treatments (3 treatments and 3 replications). Test fish were injected with 1 mg/L Pb(NO3)2 intraperitoneally. Each test animal was fed at satiation twice a day for eight days. The sampling was done on days two, four, six and eight. Parameters observed were Pb content in flesh, feces and water used in the raising activity, proximate flesh to find out the content of fat and coarse fiber in the fish flesh, histochemistry in liver and kidney, survivability, growth rate and water quality. The data analysis used was ANOVA and descriptive. AAS analysis results on flesh and feces proved that most of the Pb was excreted through feces. The highest concentration of Pb excreted through feces was in PBS treatment (1.46 mg/kg), while on days two, four, six and eight, the Pb concentrations were less than 0.001 mg/kg. The highest content of dietary
Keyword: coconut cake, palm oil cake, depuration, feed, tilapia nirwana

Judul: Depurasi Logam Berat Timbal (Pb) pada Ikan Nila (Oreochromis niloticus) dengan Menggunakan Salinitas yang Berbeda
Abstrak: Heavy metal pollution in the water is one of the limiting factor that also determine the success of aquaculture operation. The purpose of this study was to analyze the influence of salinity with increasing depuration of heavy metals Pb, which accumulate in the flesh, measured the level of oxygen consumption, growth and survival of oreochromis and analyze changes in the kidney due to histopathology gills and exposure to heavy metals. This research was carried out in February-April 2011. This research was carried out in the laboratory of the Bogor agricultural University. Results of research depuration of heavy metals indicates that there are significant differences between all treatments. The best salinity is 20 ppt, where the lowest percentage of heavy metals Pb during the process of depuration 120 hours is 1.21%. One is the level of oxygen consumption charge indicators will fish tilapia low salinity obtained at 0 ppt (0.28 0.05 mgO2/gram of fish/hour) and the highest on the salinity of 8 ppt (0.64 0.02 mgO2/g of fish/day). Low oxygen consumption indicates that the amount of energy used to metabolize a little more so that the portion of energy for greater growth. On experiment depurasi of heavy metals Pb in fish flesh of oreochromis shows response inversely between fish oreochromis growth and changes in salinity, growth pressures oreochromis more decreases the increasing salinity of the medium. The greatest growth reduction is obtained at the treatment of 20 ppt salinity is 11.64± 1.15 gr. based on the observations, the degree of survival of oreochromis high salinity media achieved at 0 ppt, 5 ppt and 10 ppt to reach 100%. Whereas on 15 and 20 ppt salinity ppt respectively reached 86.45% and 83.3%. In addition, observations of the Chemical Physics of water media maintenance which include the temperature, DO, pH and alkalinity showed conditions still favor the growth of oreochromis fish.
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Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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