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: Heavy Metal Content of Fe, Pb in Water and Tilapia (Oreochromis niloticus) in Cinangka Village, Bogor District
Abstrak: Perairan yang tercemar oleh logam berat akibat aktivitas antropogenik sangat memungkinkan terakumulasi ke dalam tubuh biota seperti ikan nila (Oreochromis niloticus) yang terdapat di wilayah perairan sekitar Desa Cinangka. Penelitian ini bertujuan menganalisis bioakumulasi kandungan logam berat timbal (Pb) dan besi (Fe) pada ikan nila serta hubungannya dengan kualitas air. Pengambilan sampel dilakukan sebanyak tiga kali pada bulan September 2020. Titik sampling yang dipilih adalah kolam pemancingan ikan yang terdapat di Desa Cinangka. Analisis konsentrasi logam berat dilakukan dengan menggunakan metode Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES). Parameter kualitas air kolam pemancingan Desa Cinangka masih sesuai dengan baku mutu. Hasil pengukuran kandungan logam Pb pada daging ikan nila berkisar antara 0,32 mg kg-1 hingga 0,4 mg kg-1 dan kandungan logam Fe sebesar 2,18 mg kg-1 hingga 3 mg kg-1. Faktor biokonsentrasi logam Pb termasuk kategori tinggi dan logam Fe termasuk kategori rendah hingga sedang. Waktu pengambilan sampel yang dilakukan tidak berpengaruh secara signifikan terhadap akumulasi logam berat pada ikan nila. Kata kunci: Bioakumulasi, Desa Cinangka, logam berat, Oreochromis niloticus, Waters polluted by heavy metals due to community activities are very likely to accumulate in the body of organism such as tilapia (Oreochromis niloticus) found in the waters around Cinangka Village. This study aims to analyze the bioaccumulation of lead (Pb) and iron (Fe) in tilapia and their relationship with water quality. Sampling was carried out three times in September 2020. The selected sampling point is a fishing pond in Cinangka Village. Heavy metal concentration analysis was carried out using the Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) method. Parameters of water quality of Cinangka Village fishing pond still in accordance with quality standards. The results of measurements of Pb metal content in tilapia ranged from 0.32 mg kg-1 to 0.4 mg kg-1 and Fe metal content was 2.18 mg kg-1 to 3 mg kg-1. Bioconcentration factor of Pb is high category and Fe metal is low to medium category. The sampling time was not significantly affected by the accumulation of heavy metals in tilapia. Keywords: Bioaccumulation, Cinangka Village, heavy metals, Oreochromis niloticus
Keyword: Bioaccumulation, Cinangka Village, heavy metals, Oreochromis niloticus

Judul: Invers dari Matriks Tridiagonal Jacobi
Abstrak: Suatu matriks berukuran n×n dinamakan matriks tridiagonal jika untuk . Karya ilmiah ini memberikan algoritma yang mudah untuk menemukan invers ( dari matriks tridiagonal Jacobi yang simetrik dan nonsimetrik. Setiap elemen pada matriks tridiagonal ini adalah bilangan real. Terdapat 3 lema dan 2 teorema untuk menentukan . Lema pertama menunjukkan persamaan utama dalam membuktikan lema-lema dan teorema-teorema selanjutnya. Invers dari matriks yang simetrik dibuktikan oleh lema kedua yang menunjukkan elemen-elemen baris ke- dari . Selanjutnya, lema kedua dilengkapi dengan teorema pertama yang menunjukkan elemen-elemen dengan . Invers dari matriks yang nonsimetrik dibuktikan oleh lema ketiga yang menunjukkan elemen-elemen dengan dan elemen-elemen dengan dibuktikankan oleh teorema kedua.
Keyword: symmetric, nonsymmetric, matrix