Coal dust explosibility meter evaluation and recommendations for application

"This report details the results of a NIOSH investigation on the ability of the Coal Dust Explosibility Meter (CDEM) to accurately predict the explosibility of samples of coal and rock dust mixtures collected from underground coal mines in the U.S. The CDEM, which gives instantaneous results in real time, represents a new way for miners and operators to assess the relative hazard of dust accumulations in their mines and the effectiveness of their rock dusting practices. The CDEM was developed by the National Institute for Occupational Safety and Health (NIOSH) and successfully underwent national and international peer review. The intention of the device is to assist mine operators in complying with the Mine Safety and Health Administration (MSHA) final rule 30 CFR* 75.403, requiring that the incombustible content of combined coal dust, rock dust, and other dust be at least 80% in underground areas of bituminous coal mines. As a final step towards commercialization of the CDEM, and to evaluate the performance of the device as a potential compliance tool, NIOSH undertook an extensive cooperative study with MSHA. This study, completed in 2009-2010, involved field use of the CDEM within MSHA's 10 bituminous coal districts. As part of their routine dust compliance surveys in these districts, MSHA inspectors collected sample coal and rock dust mixtures, field testing these samples for explosibility with the CDEM. Samples were then sent to the MSHA National Air and Dust Laboratory at Mt. Hope, WV, for parallel testing, first using a drying oven to determine the moisture followed by the traditional low temperature ashing (LTA) method. The LTA method determines explosibility of a coal and rock dust sample in a laboratory by heating the mixture to burn off the combustible material. The results, when combined with the moisture, are reported as total incombustible content (TIC). If the TIC is . 80%, the sample is deemed to be nonexplosible and compliant with 30 CFR 75.403. In the field component of this study, MSHA's use of the CDEM indicated that 30% (175) of the 591 samples collected were explosible. NIOSH was able to obtain and remeasure 297 samples, and 97% of those identified by the CDEM as being explosible (27% of samples) or nonexplosible (73% of samples) correlated with the results of the subsequent lab analysis using the LTA method. Of the remaining 3% where there were differences between the field and laboratory methods, subsequent NIOSH evaluation attributed these differences to the variability (incomplete mixing, inadequate drying of the sample, the particle size of the rock dust and/or coal dust) of the samples being analyzed, the retained moisture in those samples, and the inherent ash in the coal. In considering these results and comparing the CDEM field measurements to the LTA laboratory measurements, it is important to understand the fundamental distinctions between the two methods. The determination of TIC by the LTA method is not itself a direct measure of explosibility, but a surrogate that calculates a single parameter associated with full-scale experimental results. This method is not based on particle size and treats all particles equally regardless of the size. In contrast, the CDEM utilizes a different approach, using optical reflectance to determine the ratio of rock dust to coal dust in a mixture, with full-scale experiments on flame propagation having already demonstrated the effects of varying the coal dust particle sizes and incombustible concentrations on the explosible vs. nonexplosible dust mixtures. A final important distinction between the two methods is that the CDEM offers real-time measurements of the explosion propagation hazard within a coal mine entry, allowing for immediate identification and mitigation of the problem, while the results from the traditional LTA method are not known for days or weeks after a sample is collected, allowing for the deficiency in rock dust to continue. The conclusions of this study strongly support the field use of the CDEM to measure the explosibility of coal and rock dust mixtures, to more effectively improve the onsite adequacy of rock dusting for explosion prevention. Mine operators could use the CDEM on a regular basis to ensure that their rock dusting practices are achieving inertization requirements and meeting the intent of 30 CFR 75.403. MSHA inspectors could use the CDEM as a tool to immediately identify onsite explosibility hazards and initiate corrective action. A critical issue to both the LTA and the CDEM analysis methods is that the results are dependent on representative samples being collected for analysis." - NIOSHTIC-2Executive summary -- Introduction -- Background on coal dust and explosibility testing -- CDEM 0peration -- Comparison of laboratory results and CDEM results -- Joint study between NIOSH and MSHA -- Results and discussion -- GREEN measurements -- RED/YELLOW measurements -- Conclusions from the NIOSH study -- Commercial CDEM development -- Calibration and programming of the commercial CDEM -- Commercial CDEM changes based on potential customer concerns -- The Commercial CDEM as a verification and compliance tool -- NIOSH recommendations -- Acknowledgments -- References -- APPENDIX A: CDEM design -- APPENDIX B: CDEM training -- APPENDIX C: Prototype CDEM calibration and testing procedures used in the joint study -- APPENDIX D: Particle size effect -- APPENDIX E: MSHA inspector questions and commentsMarcia L. Harris, Michael J. Sapko, Floyd D. Varley, and Eric S. Weiss"August 2012."Also available via the World Wide Web.Includes bibliographical references (p. 25-26)

Dynamics of the HIV-2-specific immunoglobulin A(IgA) response

Millions of lives are affected by infection with HIV, which causes AIDS if untreated. HIV transmission occurs primarily through sexual contact across mucosal surfaces. In the mucosal immune response, IgA is considered the first defense line against HIV invasion. Furthermore, a recent study suggests that serum IgA can initiate phagocytosis by Kuppfer cells in vivo to avoid bacteria spreading via the blood system, which further suggests that serum IgA can serve as a second defense line. HIV-2, the second lentivirus known to cause AIDS, appears to be less pathogenic with a lower transmission rate than HIV-1. It provides an important opportunity to study immune control and pathogenesis of lentivirus infections in humans. The overall goal of our investigations was to elucidate the role of IgA in HIV-2 infection and immunity. Four studies were performed. The first study was designed to investigate the antigenic sites of HIV-2 that are important for the binding of serum IgA. We showed that serum IgA in HIV-2 infected individuals had the capacity to neutralize HIV-2. Additionally, a strong serum IgA binding activity against a peptide (aa 644-658, MYELQKLNSWDVFGN) in the region of the central part of transmembrane envelope of HIV-2 (gp36) was displayed. In the second study, we found that serum IgA in HIV-2-exposed IgG seronegative (EGSN) individuals had more potent capacity to neutralize HIV-2 than their known HIV-2 positive partners. The ratios of neutralizing titers/mg IgA (T/mg IgA) between EGSN individuals (580) and their known partners (480) was statistically significant (p<0.05). Given that IgA had potent neutralizing capacity in vitro, it may confer protection in the populations at high risk of HIV-2 exposure. This study may have important implications in understanding HIV-2 pathogenesis and transmission. In the third study, sera were collected longitudinally from a group of HIV-2 infected individuals during three-to-eight years of follow-up. We demonstrated that HIV-2-specific serum IgA has as broad binding reactivity pattern to the different antigens as IgG. Importantly, our data indicate that HIV-2 specific serum IgA may be induced independently of CD4T cells or by long lived memory B cells, since loss of CD4 T cells did not give a reduction of serum IgA. Moreover, a sustained serum IgA neutralizing capacity against HIV-2 was displayed during 8 years of follow-up. Thus, serum IgA may be associated with the lower pathogenesis and lower transmisson rates seen in HIV-2 infected individuals. Based on our prior findings, we were stimulated to explore in depth the serum IgA targeted neutralizing sites on HIV-2. Thus in a fourth study we explored the neutralization capacity of serum IgA against multiple HIV-2 strains and investigated targets for HIV-2 neutralizing IgA within the transmembrane protein (gp36) of HIV-2 in an effort to further understand the mechanism of IgAmediated immunity. We showed broad HIV-2 serum IgA-mediated neutralization against three primary isolates representing HIV-2 subtype A and B. Furthermore, our results demonstrated that two epitopes in gp36, GCAFR (aa 588-592) and MYELQ (aa 644-648), were important in mediating serum IgA antigenic binding. However, none of the selected six peptides having either the amino acid sequence GCAFR or MYELQ exhibited inhibition of IgA neutralization of HIV-2 in peptide blocking experiments. In summary, we have shown long-lived virus neutralizing HIV-2-specific serum IgA responses, which may be associated with the lower pathogenesis and lower transmisson rates seen in HIV-2 infected individuals. The importance of serum IgA was further implicated when HIV-2 exposed seronegative individuals were found to have strong serum IgA-mediated HIV-2 neutralizing activity. These studies have provided significant information important for the understanding of immune responses against HIV, particularly HIV-2, and may lay important information for the foundation of the design of an HIV vaccine

Effects of Type I Interferons on the Adjuvant Properties of Plasmid Granulocyte-Macrophage Colony-Stimulating Factor In Vivo▿

While administration of granulocyte-macrophage colony-stimulating factor (GM-CSF) can induce the local recruitment of activated antigen-presenting cells at the site of vaccine inoculation, this cellular recruitment is associated with a paradoxical decrease in local vaccine antigen expression and vaccine-elicited CD8+ T-cell responses. To clarify why this cytokine administration does not potentiate immunization, we examined the recruited cells and expressed inflammatory mediators in muscles following intramuscular administration of plasmid GM-CSF in mice. While large numbers of dendritic cells and macrophages were attracted to the site of plasmid GM-CSF inoculation, high concentrations of type I interferons were also detected in the muscles. As type I interferons have been reported to damp foreign gene expression in vivo, we examined the possibility that these local innate mediators might decrease plasmid DNA expression and therefore the immunogenicity of plasmid DNA vaccines. In fact, we found that coadministration of an anti-beta interferon monoclonal antibody with the plasmid DNA immunogen and plasmid GM-CSF restored both the local antigen expression and the CD8+ T-cell immunogenicity of the vaccine. These data demonstrate that local innate immune responses can change the ability of vaccines to generate robust adaptive immunity

ICAM-1 depletion in the center of immunological synapses is important for calcium releasing in T-cells

T-cell activation requires the formation of the immunological synapse (IS) between a T-cell and an antigen-presenting cell (APC) to control the development of the adaptive immune response. However, calcium release, an initial signal of T-cell activation, has been found to occur before IS formation. The mechanism for triggering the calcium signaling and relationship between calcium release and IS formation remains unclear. Herein, using live-cell imaging, we found that intercellular adhesion molecule 1 (ICAM-1), an essential molecule for IS formation, accumulated and then was depleted at the center of the synapse before complete IS formation. During the process of ICAM-1 depletion, calcium was released. If ICAM-1 failed to be depleted from the center of the synapse, the sustained calcium signaling could not be induced. Moreover, depletion of ICAM-1 in ISs preferentially occurred with the contact of antigen-specific T-cells and dendritic cells (DCs). Blocking the binding of ICAM-1 and lymphocyte function-associated antigen 1 (LFA-1), ICAM-1 failed to deplete at the center of the synapse, and calcium release in T-cells decreased. In studying the mechanism of how the depletion of ICAM-1 could influence calcium release in T-cells, we found that the movement of ICAM-1 was associated with the localization of LFA-1 in the IS, which affected the localization of calcium microdomains, ORAI1 and mitochondria in IS. Therefore, the depletion of ICAM-1 in the center of the synapse is an important factor for an initial sustained calcium release in T-cells

Potential Quality Evaluation Method for Radix Astragali Based on Sweetness Indicators

Sweetness is a traditional sensory indicator used to evaluate the quality of the popular Chinese herb Radix Astragali (RA). RA roots with strong sweetness are considered to be of good quality. However, neither a thorough analysis of the component(s) contributing to RA sweetness, nor a scientific investigation of the reliability of this indicator has been conducted to date. In this study, seven kinds of sweetness components were identified in RA and a quality evaluation method based on these components was established and used to characterize the quality of 48 RA samples. The sweetness evaluation method of RA was first built based on the sweetness components, and a comprehensive evaluation index commonly used in quality control of RA was also derived, which was based on the contents of four indicators (astragaloside IV, calycosin glucoside, polysaccharides and extracts). After evaluating the correlation of these indexes the results showed that the level of sweetness exhibited a strong positive correlation with the proposed comprehensive index. Our results indicate that sweetness is one of the most important quality attributes of RA and thus provide a scientific basis for the utility of the sweetness indicator in quality assessment of this Chinese herb

Potent Neutralizing Serum Immunoglobulin A (IgA) in Human Immunodeficiency Virus Type 2-Exposed IgG-Seronegative Individuals

The mechanisms behind the resistance to human immunodeficiency virus type 2 (HIV-2) infection are still not fully understood. In the present study, we explored the HIV-2-specific humoral serum immunoglobulin A (IgA) immune response in HIV-2-exposed IgG-seronegative (EGSN) individuals. Serum samples from heterosexual EGSN individuals and their known HIV-2-infected partners, as well as controls originating from Guinea-Bissau in Africa, were studied. Antibody reactivity to native and recombinant envelope glycoproteins was investigated, and the capacity of purified serum IgA to neutralize HIV-2(SBL6669) was tested. Our results showed that 16 of 25 EGSN samples exhibited reactivity against whole HIV-2 antigen, 6 of 25 samples reacted with recombinant gp36 (rgp36), and 3 of 25 samples were positive against HIV-2 rgp105; no reactivity to native HIV-2 gp125 was detected. Purified serum IgA antibodies from both EGSN and HIV-2-positive individuals, but not that from the negative controls, exhibited neutralization of HIV-2(SBL6669). The most potent neutralization activity was exhibited by IgA purified from EGSN compared to infected individuals' IgA. The antigenic pattern of the HIV-2-positive partners showed that all serum IgA samples were reactive to whole HIV-2 antigen, and 14 of 15 reacted with rgp36. For rgp105 and gp125, 5 of 15 and 4 of 15 samples exhibited binding, respectively. The serum of the EGSN group had a higher mean IgA concentration than that of the negative controls (P < 0.05). Thus, we describe HIV-2-specific serum IgA antigen reactivity and show a more potent serum IgA-mediated HIV-2-neutralizing activity in EGSN individuals than in HIV-2-infected patients

Serum immunoglobulin A (IgA)-mediated immunity in human immunodeficiency virus type 2 (HIV-2) infection

In the present study, we sought to define the importance of serum IgA (sIgA)-mediated immunity in HIV-2 infection. Serum samples from a total of 29 HIV-2-infected patients from Guinea-Bissau (n = 20) and Portugal (n = 9) were studied. Samples from seronegative individuals were used as controls. Antibody reactivity to native and recombinant envelope glycoproteins as well as peptides representing various regions of the envelope glycoproteins was investigated. Furthermore, the capacity of purified IgA to neutralize the HIV-2(SBL6669) strain was tested. All serum samples showed IgA reactivity against whole HIV-2 antigen. Twenty-eight out of 29 IgA samples (96%) reacted with native HIV-2 gp125, 26/29 (90%) with recombinant gp105, and 29/29 (100%) with recombinant gp36. When using peptides, the most prominent IgA reactivity was seen against the peptide representing as 644-658 of the transmembranous protein gp36, to which 72% of the sera reacted. Purified sIgA antibodies showed neutralizing effects against HIV-2(SBL6669) in 17/29 cases (59%). This work decribes the HIV-2-specific sIgA antigenic response. Moreover, our findings show, for the first time, that sIgA may play a role in the in vitro neutralization of HIV-2. (C) 2003 Elsevier Science (USA). All rights reserved