Nitrogen oxides emission control options for coal-fired electric utility boilers.

Recent regulations have required reductions in emissions of nitrogen oxides (NOx) from electric utility boilers. To comply with these regulatory requirements, it is increasingly important to implement state-of-the-art NOx control technologies on coal-fired utility boilers. This paper reviews NOx 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 NOx controls. The popular primary control technologies in use in the United States are low-NOx burners and overfire air. Data reflect that average NOx reductions for specific primary controls have ranged from 35% to 63% from 1995 emissions levels. The secondary NOx control technologies applied on U.S. coal-fired utility boilers include reburning, selective noncatalytic reduction (SNCR), and selective catalytic reduction (SCR). Thirty-six U.S. coal-fired utility boilers have installed SNCR, and reported NOx reductions achieved at these applications ranged from 15% to 66%. Recently, SCR has been installed at >150 U.S. coal-fired utility boilers. Data on the performance of 20 SCR systems operating in the United States with low-NOx emissions reflect that in 2003, these units achieved NOx emission rates between 0.04 and 0.07 lb/10(6) Btu.

Human patient simulation is effective for teaching paramedic students endotracheal intubation.

OBJECTIVES: The primary purpose of this study was to determine whether the endotracheal intubation (ETI) success rate is different among paramedic students trained on a human patient simulator versus on human subjects in the operating room (OR). METHODS: Paramedic students (n = 36) with no prior ETI training received identical didactic and mannequin teaching. After randomization, students were trained for ten hours on a patient simulator (SIM) or with 15 intubations on human subjects in the OR. All students then underwent a formalized test of 15 intubations in the OR. The primary outcome was the rate of successful intubation. Secondary outcomes were the success rate at first attempt and the complication rate. The study was powered to detect a 10% difference for the overall success rate (alpha = 0.05, beta = 0.20). RESULTS: The overall intubation success rate was 87.8% in the SIM group and 84.8% in the OR group (difference of 3.0% [95% confidence interval {CI} = -4.2% to 10.1%; p = 0.42]). The success rate on the first attempt was 84.4% in the SIM group and 80.0% in the OR group (difference of 4.4% [95% CI = -3.4% to 12.3%; p = 0.27]). The complication rate was 6.3% in the SIM group and 4.4% in the OR group (difference of 1.9% [95% CI = -2.9% to 6.6%; p = 0.44]). CONCLUSIONS: When tested in the OR, paramedic students who were trained in ETI on a simulator are as effective as students who trained on human subjects. The results support using simulators to teach ETI.

Erythrocyte-rosetting properties of feline blood lymphocytes and their relationship to monoclonal antibodies to T lymphocytes.

Rosette formation of feline peripheral blood leukocytes with guinea pig (GP) and gerbil (G) erythrocytes (E) has been shown in an earlier study to identify T lymphocytes expressing helper and suppressor cell activity, respectively. This T lymphocyte distinction was based on the removal of the E-rosetting populations from peripheral blood leukocytes (PBL) and the subsequent functional evaluation of the remaining cells in a pokeweed mitogen (PWM)-induced synthesis of immunoglobulin (Ig). In the present study, we demonstrate a direct helper and suppressor function of GPE- and GE-rosetted cells, respectively, wherein the induction of Ig synthesis is altered in a positive or negative way by the addition of the cells to a control target population. A pan-T monoclonal antibody (mAb), CT843, and mAbs to the CD4 (CT248) and CD8 (CT87) subsets are also described; their specificities are established in functional assays, the PWM-induced Ig synthesis and the production of interleukin-2 following Concanavalin A stimulation of PBL, and a biochemical analysis of the surface membrane antigens detected by the mAbs. Immunoprecipitation and SDS-PAGE analyses showed CT248 to react with a approximately 60-kDa protein under both reducing and nonreducing conditions. Under reducing conditions, CT87 reacted with one subunit at approximately 35 kDa; a second faint band at approximately 39 kDa was poorly resolved. mAb CT843 detected a heterodimer of approximately 70 and approximately 60 kDa under both reducing and nonreducing conditions. The relationship of the mAbs to E-rosetting was examined in FACScan analyses and rosette inhibition studies. The percentage of GE-rosetting cells agreed with the percentage of cells stained with the CD8 mAb, whereas a comparison of GPE-rosetting and staining with the CD4 mAb showed variability. The binding of GE to PBL was blocked by pretreatment of PBL with the CD8 mAb, whereas no inhibition of GPE rosettes was observed with any of the mAbs. In a previous study, we had shown that an overnight culture of feline PBL at 37 degrees C leads to the development of a second population of GPE-rosetting cells, also having a helper function. The relationship of the two GPE-rosetting populations to the CD4 mAb, CT248, was examined in rosette depletion studies and FACScan analyses. It was found that depletion of the GPE-rosetting cells from fresh, i.e., Day 0 cells, removed only a small percentage of cells reactive with the CD4 mAb, whereas GPE-rosette depletions performed on Day 1 PBL, which contained both populations of GPE-rosetting cells, removed almost all cells reactive with this antibody. The latter study suggests that the GPE-rosetting phenomenon is detecting two subsets of CD4 cells with T helper function, those present in fresh blood and those acquiring the GPE receptor after an overnight culture.