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"Pabrik pengeringan konsentrat tembaga memiliki peranan penting sebagai tahap akhir dalam proses penambangan tembaga. Keberlangsungan operasi pabrik sangat dipengaruhi oleh kondisi bangunan dan fasilitas yang berbahan dasar baja. Persentase tembaga yang ada dalam konsentrat berkisar antara 20-40 %, Kalkopirit memiliki jumlah tembaga yang besar pada akhir ekstraksi. Pengaruh kehadiran kalkopirit dapat meningkatkan laju korosi pada baja melalui pasangan galvanik. pemilihan sistem coating untuk mellindungi baja menjadi penting dimana ketahanan material coating dipengaruhi oleh kekuatan terhadap cacat pada lapisan. Pada penelitian ini lima sistem organik coating yang diaplikasikan pada baja karbon A 36 dievaluasi kekuatannya terhadap korosi akibat kehadiran konsentrat tembaga dengan metode Electrochemical Impedance Spectroscopy (EIS), uji sembur garam dan uji tarik. Hasil pengujian menunjukkan bahwa sistem coating C2, C3, C4 dan C5 mempertahankan sifat penghalang yang baik selama proses perendaman, nilai impedansi |Z| pada frekuensi rendah lebih dari 108 Ω.cm2 setelah 30 hari. Coating modifikasi epoksi (C1) memiliki impedansi terendah dengan resistansi di bawah 106 Ω.cm2 memberikan perlindungan korosi yang buruk

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The copper concentrate dewatering plant has an important role as a step end in the copper mining process. The continuity of plant operation is very influenced by the condition of buildings and facilities made of steel. Percentage of copper present in the copper concentrate is in the range of 20 to 40 %. Thus, Chalcopyrite is preferable to get large amount of copper at the end of the extraction. The presence of chalcopyrite increases the corrosion rate of carbon steel through a galvanic couple. Probably the most important step in coating selection is to evaluate the conditions under which the coating must perform. In this study, five organic coating systems were applied to A-36 steel and evaluated evaluated for their strength against galvanic corrosion in the presence of copper concentrate by electrochemistry impedance spectroscopy (EIS) measurement, salt spray test and pull off test. The test results showed that C2, C3, C4 and C5 coating systems maintained good barrier property during the immersion process, the impedance value |Z| at a low frequency are more than 108 Ω.cm2 after 30 days in immersion exposure. Epoxy modified coating (C1) had the lowest impedance with resistance under 106 Ω.cm2 providing poor corrosion protection."

"Human teeth enamel have been irradiated with gamma radiation from Co60 at room temperature and at liquid nitrogen temperature. Paramagnetic centers are formed and have been detected by using electron spin resonance (ESR) spectrometer at room temperature. The main signal is very stable asymmetric singlet, and attributed to h centers in the hydroxyapatite crystals. It is revealed that several factors influence the amplitude of the asymmetric signal. The amplitude and pattern of the asymmetric signal which depend on the orientation of the sample with respect to the magnetic field are analyzed. Based on the properties of the asymmetric signal the difference between the microcrystal arrangement of healthy and diseased teeth are explained."