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Recent regulations have required reductions in emissions of nitrogen oxides (NO x ) from electric utility boilers. To comply with these regulatory requirements, it is increasingly important to implement state-of-the-art NO x control technologies on coal-fired utility boilers. This paper reviews NO x control options for these boilers. It discusses the established commercial primary and secondary control technologies and examines what is being done to use them more effectively. Furthermore, the paper discusses recent developments in NO x controls. The popular pri-

In the present paper we report that the ROHA -9 cell line, an Epstein-Barr virus (EBV)-transformed human B cell line with accessory cell capabilities, constitutively secretes a soluble factor with the biochemical and biological characteristics of human monocyte-derived IL-1. The IL-1 derived from ROHA -9 augmented murine thymocyte proliferation and enhanced the proliferative response of human T lymphocytes to concanavalin A (Con A). The ROHA -9-derived IL-1 activity eluted from Sephacryl S-200 in two peaks, at 15- 18K and 32- 35K mol wt, eluted from DEAE-Sephacel at 50-80 and 110-130 mM NaCl, and showed charge heterogeneity with peaks at pI 7.3, 6.1, and 4.1 on isoelectrofocusing (IEF). These findings suggest that B cells may elaborate an IL-1-like activity. During the logarithmic growth of ROHA -9 cells, a inhibitory factor that inhibited the response of mouse thymocytes to IL-1 was also produced. This factor had a mol wt of 95K on Sephacryl S-200, eluted at 150 mM NaCl on DEAE-Sephacel and showed a peak of pI 4.7 on preparative IEF. The inhibitory factor appeared to be selective in its effects on IL-1 responses, since it did not inhibit the activity of IL-2 on mouse thymocytes or on the growth of the IL-2-dependent CT6 cell line. This "contra-IL-1" inhibited the response of murine thymocytes to suboptimal (1 microgram/ml) but not optimal (10 micrograms/ml) doses of Con A and the response of human peripheral blood lymphocytes to streptolysin O ( SLO ) or to alloantigens. Moreover, the factor could be absorbed by mouse thymocytes but not by CT6 cells, and such thymocytes pretreated with contra-IL-1 failed to response to IL-1. Although this inhibitor is the product of a transformed B cell line, it may be representative of regulatory substances that normally control IL-1 activities either at the extracellular or intracellular level.

The role of coal combustion as a significant global source of nitrous oxide (N2O) emissions was reexamined through on‐line emission measurements from six pulverized‐coal‐fired utility boilers and from laboratory and pilot‐scale combustors. The full‐scale utility boilers yielded direct N2O emission levels of less than 5 ppm. The sub‐scale combustor test data were consistent with full‐scale data, and also showed N2O emission levels not exceeding 5 ppm, although these levels increased slightly when various combustion modifications to lower NO emissions were employed. These on‐line emission measurements are very different from previously published data. The discrepancy is shown to be due to a sampling artifact by which significant quantities of N2O can be produced in sample containers which have been used in establishing the previously employed N2O data base. Consequently, we conclude that N2O emissions bear no direct relationship to NO emissions from these combustion sources, and that this direct source of N2O is negligible. Other indirect routes for the conversion of NO into N2O outside the combustor and other combustion sources not examined by this study, however, cannot be ruled out.