Mercury in U.S. Coal - Abundance, Distribution, and Modes of Occurrence

This paper discusses the environmental significance of mercury and its occurrence in U.S. coal beds as measured by the USGS's COALQUAL database. Useful diagrams and charts help explain mercury concentrations of in-ground coal by region, how mercury is released through coal combustion, and why using higher grade coals or physically cleaning coal can minimize mercury emissions during combustion. The paper also discusses additional studies to determine how the mode of occurrence of mercury in coal may influence the potential for toxic emissions. Educational levels: Graduate or professional, Undergraduate upper division

Computerized Calculation of Lignite Resources in Texas

The Bureau of Economic Geology (BEG) is currently utilizing the National Coal Resources Data System (NCRDS) to estimate near-surface lignite resources in the state of Texas. Data provided to the BEG for this project primarily consist of geophysical logs from holes drilled for lignite exploration. These logs, obtained from industry sources on a proprietary basis, typically include density and resistivity traces, with occasional availability of natural gamma data. The boreholes average 150-200 ft in depth, with some reaching depths of up to 300 ft. Due to the distribution of the data, accurate correlation of individual lignite seams is challenging. Therefore, resources are calculated by summing the thicknesses of seams encountered in each borehole (total lignite). There is no standardized NCRDS method for selecting data for the calculation of total coal resources; however, the BEG has developed a method through a series of trial methods. The process begins with using PACER to search TXSTRAT for all information within a specified topographic quadrangle and a surrounding three-mile border. The additional border is included to ensure that resource calculation encompasses inferred resources from points located outside the quadrangle's latitudinal and longitudinal limits. All non-lignite (rock) lithologies in this initial file are then set to zero thickness, resulting in a file containing all data point locations with zero total thickness. Next, the initial file is searched again for lignite lithologies in the three thickness categories specified by the USGS and two additional thickness categories used in Texas (2 to 3 ft, and greater than or equal to 3 ft). Five lignite files are generated based on these thickness categories and merged one at a time with the zero-thickness file. The thicknesses are then summed in each borehole for all five files. Data locations (boreholes) without coal or with seams thinner or thicker than the searched thickness category are assigned zero total thickness. This control mechanism improves interpolation of thicknesses between points. While subsequent resource estimates may be conservative, this method prevents unrealistically large tonnages in the inferred resource category, addressing a major issue observed in earlier methods.Bureau of Economic Geolog

Upstream toward the “DRiP”-ing Source of the MHC Class I Pathway

MHC class I binding peptides are generated via cytosolic degradation of a previously undefined substrate. In this issue of Immunity, Kunisawa and Shastri (2006) isolate pre-degradation polypeptide intermediates bound to a cytosolic chaperone

The WUTC threshold test: a new perspective in olfactory assessment

The WUTC Threshold Test is a new test of olfactory ability that focuses on the idea that deficits in olfactory ability are not necessarily generalizable to all odors. Though numerous diseases and disorders have been shown to lead to a loss of olfaction, tests of olfactory sensitivity have been limited to performance detecting a single odor. The WUTC is comprised of five odors that were selected based on differences in how they interact with the olfactory system and the chemical properties they possess. By utilizing a diverse odor profile, relationships between olfactory deficits to certain odors and specific diseases can be explored. The test also employs randomized, multiple presentation of odorants along with null-stimulus trials. Using this methodology, statistical measures of participant sensitivity, response-bias, threshold, and inter-rater reliability can be calculated with a single administration of the test. A pilot study, consisting of thirty three (N=33) participants, was conducted. Subject demographic data was also collected in order to conduct exploratory analyses and aid in the further development of the test. The reasoning and methodology of the WUTC Threshold test are discussed along with the analyses of the subject data. The results of this pilot study suggest that certain ailments do not have significant olfactory deficits to all odorants, only particular odor molecules. The principles behind the development of the WUTC Threshold Test may lead to the further understanding of links between olfaction and disease and an increase in the value of examining olfactory ability in a clinical setting

The geochemistry of environmentally important trace elements in UK coals, with special reference to the Parkgate coal in the Yorkshire-Nottinghamshire Coalfield, UK

The Parkgate coal of Langsettian age in the Yorkshire-Nottinghamshire coalfield is typical of many coals in the UK in that it has a high sulphur (S) content. Detailed information on the distribution of the forms of S, both laterally and vertically through the seam, was known from previous investigations. In the present work, 38 interval samples from five measured sections of the coal were comprehensively analysed for major, minor and trace elements and the significance of the relationships established using both raw and centered log transformed data. The major elements are used to quantify the variations in the inorganic and organic coal components and determine the trace element associations. Pyrite contains nearly all of the Hg, As, Se, Tl and Pb and is also the major source of the Mo, Ni, Cd and Sb. The clays contain the following elements in decreasing order of association: Rb, Cs, Li, Ga, U, Cr, V, Sc, Y, Bi, Cu, Nb, Sn, Te and Th. Nearly all of the Rb is present in the clay fraction, whereas for elements such as V, Cu and U, a significant amount is thought to be present in the organic matter, based on the K vs trace element regression equations. Only Ge, and possibly Be, would appear to have a dominant organic source. The trace element concentrations are calculated for pyrite, the clay fraction and organic matter. For pyrite it is noted that concentrations agree with published data from the Yorkshire-Nottinghamshire coalfield and also that Tl concentrations (median of 0.33 ppm) in the pyrite are greater than either Hg or Cd. Unlike these elements, Tl has attracted less attention and possibly more information is needed on its anthropogenic distribution and impacts on man and the environment. A seawater source is thought to be responsible for the high concentrations of S, Cl and the non-detrital trace elements in the Parkgate coal. Indicative of the seawater control is the Th/U ratio, which expresses the detrital to non-detrital element contributions. Using other elements, similar ratios can be calculated, which in combination offer greater interpretative value. (C) 2009 Elsevier B.V. All rights reserved

Viral Sequestration of Antigen Subverts Cross Presentation to CD8+ T Cells

Virus-specific CD8+ T cells (TCD8+) are initially triggered by peptide-MHC Class I complexes on the surface of professional antigen presenting cells (pAPC). Peptide-MHC complexes are produced by two spatially distinct pathways during virus infection. Endogenous antigens synthesized within virus-infected pAPC are presented via the direct-presentation pathway. Many viruses have developed strategies to subvert direct presentation. When direct presentation is blocked, the cross-presentation pathway, in which antigen is transferred from virus-infected cells to uninfected pAPC, is thought to compensate and allow the generation of effector TCD8+. Direct presentation of vaccinia virus (VACV) antigens driven by late promoters does not occur, as an abortive infection of pAPC prevents production of these late antigens. This lack of direct presentation results in a greatly diminished or ablated TCD8+ response to late antigens. We demonstrate that late poxvirus antigens do not enter the cross-presentation pathway, even when identical antigens driven by early promoters access this pathway efficiently. The mechanism mediating this novel means of viral modulation of antigen presentation involves the sequestration of late antigens within virus factories. Early antigens and cellular antigens are cross-presented from virus-infected cells, as are late antigens that are targeted to compartments outside of the virus factories. This virus-mediated blockade specifically targets the cross-presentation pathway, since late antigen that is not cross-presented efficiently enters the MHC Class II presentation pathway. These data are the first to describe an evasion mechanism employed by pathogens to prevent entry into the cross-presentation pathway. In the absence of direct presentation, this evasion mechanism leads to a complete ablation of the TCD8+ response and a potential replicative advantage for the virus. Such mechanisms of viral modulation of antigen presentation must also be taken into account during the rational design of antiviral vaccines

Lymphatic endothelial cells are a replicative niche for Mycobacterium tuberculosis

In extrapulmonary tuberculosis, the most common site of infection is within the lymphatic system, and there is growing recognition that lymphatic endothelial cells (LECs) are involved in immune function. Here, we identified LECs, which line the lymphatic vessels, as a niche for Mycobacterium tuberculosis in the lymph nodes of patients with tuberculosis. In cultured primary human LECs (hLECs), we determined that M. tuberculosis replicates both in the cytosol and within autophagosomes, but the bacteria failed to replicate when the virulence locus RD1 was deleted. Activation by IFN-γ induced a cell-autonomous response in hLECs via autophagy and NO production that restricted M. tuberculosis growth. Thus, depending on the activation status of LECs, autophagy can both promote and restrict replication. Together, these findings reveal a previously unrecognized role for hLECs and autophagy in tuberculosis pathogenesis and suggest that hLECs are a potential niche for M. tuberculosis that allows establishment of persistent infection in lymph nodes

Coal-derived rates of atmospheric dust deposition during the Permian

Despite widespread evidence for atmospheric dust deposition prior to the Quaternary, quantitative rate data remains sparse. As dust influences both climate and biological productivity, the absence of quantitative dust data limits the comprehensiveness of models of pre-Quaternary climate and biogeochemical cycles. Here, we propose that inorganic matter contained in coal primarily records atmospheric dust deposition. To test this, we use the average concentration of inorganic matter in Permian coal to map global patterns and deposition rates of atmospheric dust over Pangea. The dust accumulation rate is calculated assuming Permian peat carbon accumulation rates in temperate climates were similar to Holocene rates and accounting for the loss of carbon during coalification. Coal-derived rates vary from 0.02 to 25 g m− 2 year− 1, values that fall within the present-day global range. A well-constrained East–West pattern of dust deposition corresponding to expected palaeoclimate gradients extends across Gondwana with maximum dust deposition rates occurring close to arid regions. A similar pattern is partially defined over the northern hemisphere. Patterns are consistent with the presence of two large global dust plumes centred on the tropics. The spatial patterns of dust deposition were also compared to dust cycle simulations for the Permian made with the Community Climate System Model version 3 (CCSM3). Key differences between the simulations and the coal data are the lack of evidence for an Antarctic dust source, higher than expected dust deposition over N and S China and greater dust deposition rates over Western Gondwana. This new coal-based dust accumulation rate data expands the pre-Neogene quantitative record of atmospheric dust and can help to inform and validate models of global circulation and biogeochemical cycles over the past 350 Myr

Binding of Hyaluronan to the Native Lymphatic Vessel Endothelial Receptor LYVE-1 Is Critically Dependent on Receptor Clustering and Hyaluronan Organization

The lymphatic endothelial receptor LYVE-1 has been implicated in both uptake of hyaluronan (HA) from tissue matrix and in facilitating transit of leukocytes and tumor cells through lymphatic vessels based largely on in vitro studies with recombinant receptor in transfected fibroblasts. Curiously, however, LYVE-1 in lymphatic endothelium displays little if any binding to HA in vitro, and this has led to the conclusion that the native receptor is functionally silenced, a feature that is difficult to reconcile with its proposed in vivo functions. Nonetheless, as we reported recently, LYVE-1 can function as a receptor for HA-encapsulated Group A streptococci and mediate lymphatic dissemination in mice. Here we resolve these paradoxical findings and show that the capacity of LYVE-1 to bind HA is strictly dependent on avidity, demanding appropriate receptor self-association and/or HA multimerization. In particular, we demonstrate the prerequisite of a critical LYVE-1 threshold density and show that HA binding may be elicited in lymphatic endothelium by surface clustering with divalent LYVE-1 mAbs. In addition, we show that cross-linking of biotinylated HA in streptavidin multimers or supramolecular complexes with the inflammation-induced protein TSG-6 enables binding even in the absence of LYVE-1 cross-linking. Finally, we show that endogenous HA on the surface of macrophages can engage LYVE-1, facilitating their adhesion and transit across lymphatic endothelium. These results reveal LYVE-1 as a low affinity receptor tuned to discriminate between different HA configurations through avidity and establish a new mechanistic basis for the functions ascribed to LYVE-1 in matrix HA binding and leukocyte trafficking in vivo