Investigation of modified speciation for enhanced control of mercury

Mercury was identified as a hazardous air pollutant in Title 3 of the 1990 Clean Air Act Amendments. It has been singled out for particular scrutiny because of its behavior in the environment (bioaccumulation) and its potential for deleterious effects on humans and wildlife. After studying the sources of mercury in the environment, the US Environmental Protection Agency has concluded that coal-fired boilers generate a significant fraction of the total anthropogenic emissions. Therefore, the agency is currently considering whether to impose mercury control requirements on coal-fired boilers in the electric utility industry. However, the costs for potential control measures (such as sorbent injection) can be extremely high. Mercury removal with chloric acid solutions was tested. The presence of NO increased Hg removal. It appeared that both gas-gas and gas-liquids reactions were operating, with the gas-phase reactions involving NO becoming increasingly important as the solute concentration was raised. From these studies, it was concluded that even higher Hg{sup 0} removals could be obtained if more of the reagent was made available for reaction in the gas phase. For this reason (and also to simulate a more real-world duct-injection process) a new series of tests was initiated in which an ultrasonic atomizer was used to inject small droplets of the oxidizing solutions into a flowing gas stream containing Hg{sup 0} vapors and other typical flue-gas components. The results of those tests are described in this paper

Critical Review of Mercury Chemistry in Flue Gas.

Mercury (Hg) and its compounds have long been recognized as potentially hazardous to human health and the environment. Many man-made sources of mercury have been reduced in recent years through process changes and control measures. However, emissions of mercury from coal-fired power plants, while exceedingly dilute by the usual pollution standards, still constitute a major source when considered in the aggregate. Concerns over those emissions and the prospect of impending emissions regulations have led to a wide range of research projects dealing with the measurement and control of mercury in flue gas. This work has made considerable progress in improving the understanding of mercury emissions and their behavior, but inconsistencies and unexpected results have also shown that a better understanding of mercury chemistry is needed. To develop a more complete understanding of where additional research on mercury chemistry is needed, the U.S. Department of Energy (DOE) asked Argonne National Laboratory (Argonne) to conduct a critical review of the available information as reported in the technical literature. The objectives were to summarize the current state of the art of chemistry knowledge, identify significant knowledge gaps, and recommend future research to resolve those gaps. An initial evaluation of potential review topics indicated that the scope of the review would need to be limited and focused on the most important topics relative to mercury control. To aid in this process, Argonne developed a brief survey that was circulated to researchers in the field who could help identify and prioritize the many aspects of the problem. The results of the survey were then used to design and guide a highly focused literature search that identified key papers for analysis. Each paper was reviewed, summarized, and evaluated for the relevance and quality of the information presented. The results of that work provided the basis for conclusions regarding the state of knowledge of mercury chemistry and recommendations for further research. This report begins by summarizing the survey process and describing how the results were used to shape the critical review. Analyses of information obtained from the various publications are presented chronologically, beginning with the earliest relevant publication found and concluding with the end of the review in early 2003. Finally, the conclusions and recommendations for future research are presented. The survey instrument is included in Appendix A, while detailed information on each of the publications reviewed is given in Appendix B

Spectroscopic Study of 75^{75}As and 139^{139}La NMR on Layered Structure Ferromagnet LaCoAsO

$^{75}$As and $^{139}$La field-swept NMR spectra were obtained for the novel weakly itinerant ferromagnet LaCoAsO with 2D layered structure above the Curie temperature of 55 K. By analyzing NMR spectra, temperature dependences of Knight shift $K$ and nuclear quadrupole resonance frequency $\nu_Q$ were obtained successfully for each nucleus. We confirmed from the so-called $K$-$\chi$ plots that the macroscopic magnetization of our {LaCoAsO} powder sample is intrinsic and does not contain the contribution from impurity phases. We estimated hyperfine coupling constants from the slope of $K$-$\chi$ plots and compared to that of iron-arsenide superconductor.Comment: 5 pages, 5 figures, published on J. Phys. Soc. Jpn. at Vol.79, pp.054703 (2010)

Developmental expression of retinoic acid receptors (RARs)

Here, I review the developmental expression features of genes encoding the retinoic acid receptors (RARs) and the 'retinoid X' or rexinoid receptors (RXRs). The first detailed expression studies were performed in the mouse over two decades ago, following the cloning of the murine Rar genes. These studies revealed complex expression features at all stages of post-implantation development, one receptor gene (Rara) showing widespread expression, the two others (Rarb and Rarg) with highly regionalized and/or cell type-specific expression in both neural and non-neural tissues. Rxr genes also have either widespread (Rxra, Rxrb), or highly-restricted (Rxrg) expression patterns. Studies performed in zebrafish and Xenopus demonstrated expression of Rar and Rxr genes (both maternal and zygotic), at early pre-gastrulation stages. The eventual characterization of specific enzymes involved in the synthesis of retinoic acid (retinol/retinaldehyde dehydrogenases), or the triggering of its catabolism (CYP26 cytochrome P450s), all of them showing differential expression patterns, led to a clearer understanding of the phenomenons regulated by retinoic acid signaling during development. Functional studies involving targeted gene disruptions in the mouse, and additional approaches such as dominant negative receptor expression in other models, have pinpointed the specific, versus partly redundant, roles of the RARs and RXRs in many developing organ systems. These pleiotropic roles are summarized hereafter in relationship to the receptors’ expression patterns

Enhancement of mercury control in flue-gas cleanup systems

This paper summarizes research at Argonne National Laboratory which is focused on techniques to enhance the capture of elemental mercury and integrate its control into existing flue-gas cleanup (FGC) systems. Both laboratory and field tests have shown that very little elemental mercury is captured in a wet scrubber system due to the low solubility of that species. To enhance the ability of wet scrubbers to capture mercury, Argonne has studied improved mass transfer through both mechanical and chemical means, as well as the conversion of elemental mercury into a more soluble species that can be easily absorbed. Current research is investigating the roles of several halogen species either alone or in combination with typical flue-gas components such as sulfur dioxide and nitric oxide in the oxidation of mercury to form compounds that are easily scrubbed from the flue gas

A Replication of Failure, Not a Failure to Replicate

Purpose: The increasing role of systematic reviews in knowledge production demands greater rigor in the literature search process. The performance of the Social Work Abstracts (SWA) database has been examined multiple times over the past three decades. The current study is a replication within this line of research. Method: Issue level coverage was examined for the same 33 SWA core journals and the same time period as our 2009 study. Results: The mean percentage of issues missing in the current study was 20%. The mean percentage of issues missing in the current study was significantly greater than the mean percentage of issues missing in the 2009 study. Discussion: The research of other groups, and that of our own, has failed to prompt NASW Press to act. SWA was failing, it is failing and NASW Press has failed to correct those failures

Functional consequence of the MET-T1010I polymorphism in breast cancer.

Major breast cancer predisposition genes, only account for approximately 30% of high-risk breast cancer families and only explain 15% of breast cancer familial relative risk. The HGF growth factor receptor MET is potentially functionally altered due to an uncommon germline single nucleotide polymorphism (SNP), MET-T1010I, in many cancer lineages including breast cancer where the MET-T1010I SNP is present in 2% of patients with metastatic breast cancer. Expression of MET-T1010I in the context of mammary epithelium increases colony formation, cell migration and invasion in-vitro and tumor growth and invasion in-vivo. A selective effect of MET-T1010I as compared to wild type MET on cell invasion both in-vitro and in-vivo suggests that the MET-T1010I SNP may alter tumor pathophysiology and should be considered as a potential biomarker when implementing MET targeted clinical trials

Cardiovascular roles of estrogen receptors: insights gained from knockout models

The effects of estrogen are mediated through two functionally distinct receptors, estrogen receptor α (ER- α ), and estrogen receptor β (ER- β ), both of which are expressed in the cardiovascular system. The etiology of cardiovascular disease is believed to result in part from the loss of endogenous estrogen, indicating that estrogen and its receptors may play important roles in the prevention of cardiovascular disease in women