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Sulfur dioxide (SO2) is a type of the main air pollutants in sintering flue gas. SO2 has received ex-tensive attentions because it is a precursor of envi-ronmental acidification. According to the influential parameters of the sintering process and the material composition of sintering mixture, the formation process of SO2 during the rise of sinter temperature from 25 °C to 1000 °C has been studied in this paper. And the results show that 66.67% sulfur in the sintering mixture is released in the form of SO2 into the sintering flue gas under different sinter temperatures. Producing reactions of SO2 tend to be drastic when the sinter temperature rises up to 700 °C. The mass of SO2 produced during the temperature rises from 700 °C to 1000 °C occupies 91.66% of the total SO2 in the sintering process. Analysis on material balance suggests that concentration of SO2 released from the sintering is related not only with the sinter temperature, but also with the content of S in the coke and the alkalinity of sintering mixture. The rising coke content promotes the release of SO2, and the peak concentration of SO2 reaches 229 mg/m³ when the coke content is 7%. CaCO3 in sintering mixture has a suppression effect on SO2, and the peak concentration of SO2 is only 112 mg/m3 when the alkalinity of sintering mixture is 2.0. [ABSTRACT FROM AUTHOR]

Background: Pregnancy-associated plasma protein A (PAPP-A) was first found in the serum of pregnant women and then found to be associated with acute coronary syndrome (ACS). Unfortunately, the sensitivity and specificity of current detection methods are poor, so the present work aimed to improve them. The successful detection of PAPP-A could be widely applicable clinically., Methods: We used affinity chromatography to purify the PAPP-A antigen, which was used to prepare the antibody. A biotin-avidin enzyme-linked immunosorbent assay (BA-ELISA) was developed to detect low levels of PAPP-A. Nonspecific reactions were excluded by using affinity chromatography and papain digestion to remove the Fc fragment of the antibody., Results: The BA-ELISA method we developed was more sensitive than traditional ELISA, as all nonspecific reactions were excluded. Its sensitivity was 0.065 mIU/L and recovery of PAPP-A from samples was 98.51%. The specificity was also much better than with standard ELISA kits., Conclusions: Affinity chromatography and papain digestion have important effects on the assay specificity. The BA-ELISA method proved sensitive and nonspecific reactions were excluded. The method is easily carried out, so it is suitable for detecting PAPP-A in the serum of patients with ACS.