Effects of CO2 storage in coal on coal properties

AbstractUnlike other storage options, CO2 storage in coal seams is still in its infancy and requires advanced research to address the number of unknowns. One of the many questions that still need to be answered concerns the long term effects of storing CO2 in coal, specifically on the structure and properties of the coal. Most studies on coal structural changes have been conducted over a short period of adsorption (hours or 2-3 days) and at low pressures (1-20bar). Available literature has shown that the volumetric strains are a function of the local petrographic composition, and, in general, a coal's response to CO2 sorption is based on the coal petrographic composition. The aim of this study was to determine any molecular structural and physical changes that may occur in coal following long term exposure (up to 6 months) to CO2 under subcritical conditions (up to 42bar). Inertinite-rich coal particles have a higher microporous surface area than vitrinite-rich particles of the same rank, as demonstrated by BET analysis. XRD results on the pre- and post-sorption coal samples demonstrated that CO2 sorption in coal causes some structural changes. The structural changes were found to be different for coals of different maceral composition, confirming the initial hypothesis. The coal samples that were exposed to CO2 over longer periods of time (6 months) displayed a more pronounced change in coal structure than those that were exposed for a shorter period of time (14 days). Volumetric sorption studies demonstrated that CO2 treated vitrinite-rich particles have a greater change in sorption properties than inertinite-rich particles. The study provides an insight into the chemical and physical changes caused by sorption of CO2 into coal, and could be used for modelling CO2-coal interactions, and for assisting in CO2-coal uptake calculations

Migmatite-Like Textures in Anthracite: Further Evidence for Low-Grade Metamorphic Melting and Resolidification in High-Rank Coals

Previous studies demonstrated that melting, initiated by supercritical fluids in the 375–400 °C range, occurred as part of anthracite metamorphism in the Appalachian Basin. Based on the known behavior of vitrinite at high temperatures and, to a lesser extent, at high pressures, it was determined that the duration of the heating, melting, and resolidification event was about 1 h. In the current study, featureless vitrinite within banded maceral assemblages demonstrates the intimate association of melted and resolidified vitrinite with anthracite-rank macerals. By analogy with metamorphosed inorganic rocks, such associations represent diadysites and embrechites, i.e., cross-cutting and layered migmatites, respectively. Even though the temperature of formation of the anthracite structures is several hundred °C lower than that seen in metamorphosed inorganic rocks, anthracites are metamorphic rocks and the nomenclature for metamorphic rocks may be appropriate for coal

Comparative study of a vitrinite-rich and an inertinite-rich Witbank coal (South Africa) using pyrolysis-gas chromatography

Abstract This study aims to compare iso-rank vitrinite-rich and inertinite-rich coal samples to understand the impact of coal-forming processes on pyrolysis chemistry. A medium rank C bituminous coal was density-fractionated to create a vitrinite-rich and an inertinite-rich sub-sample. The vitrinite-rich sample has 83 vol% total vitrinite (mineral-matter-free basis), whereas the inertinite-rich counterpart has 66 vol% total inertinite. The vitrinite-rich sample is dominated by collotelinite and collodetrinite. Fusinite, semifusinite, and inertodetrinite are the main macerals of the inertinite-rich sample. Molecular chemistry was assessed using a pyrolysis gas chromatograph (py-GC) equipped with a thermal desorption unit coupled to a time of flight mass spectrometer (MS) (py-GC/MS) and solid-state nuclear magnetic resonance (13C CP-MAS SS NMR). The pyrolysis products of the coal samples are generally similar, comprised of low and high molecular weight alkanes, alkylbenzenes, alkylphenols, and alkyl-subtituted polycyclic aromatic hydrocarbons, although the vitrinite-rich sample is chemically more diverse. The lack of diversity exhibited by the inertinite-rich sample upon pyrolysis may be interpreted to suggest that major components were heated in their geologic history. Based on the 13C CP-MAS SS NMR analysis, the inertinite-rich sample has a greater fraction of phenolics, reflected in the py-GC/MS results as substituted and unsubstituted derivatives. The greater abundance of phenolics for the inertinite-rich sample may suggest a fire-related origin for the dominant macerals of this sample. The C2-alkylbenzene isomers (p-xylene and o-xylene) were detected in the pyrolysis products for the vitrinite-rich and inertinite-rich samples, though more abundant in the former. The presence of these in both samples likely reflects common source vegetation for the dominant vitrinite and inertinite macerals

Regulatory control and the costs and benefits of biochemical noise

Experiments in recent years have vividly demonstrated that gene expression can be highly stochastic. How protein concentration fluctuations affect the growth rate of a population of cells, is, however, a wide open question. We present a mathematical model that makes it possible to quantify the effect of protein concentration fluctuations on the growth rate of a population of genetically identical cells. The model predicts that the population's growth rate depends on how the growth rate of a single cell varies with protein concentration, the variance of the protein concentration fluctuations, and the correlation time of these fluctuations. The model also predicts that when the average concentration of a protein is close to the value that maximizes the growth rate, fluctuations in its concentration always reduce the growth rate. However, when the average protein concentration deviates sufficiently from the optimal level, fluctuations can enhance the growth rate of the population, even when the growth rate of a cell depends linearly on the protein concentration. The model also shows that the ensemble or population average of a quantity, such as the average protein expression level or its variance, is in general not equal to its time average as obtained from tracing a single cell and its descendants. We apply our model to perform a cost-benefit analysis of gene regulatory control. Our analysis predicts that the optimal expression level of a gene regulatory protein is determined by the trade-off between the cost of synthesizing the regulatory protein and the benefit of minimizing the fluctuations in the expression of its target gene. We discuss possible experiments that could test our predictions.Comment: Revised manuscript;35 pages, 4 figures, REVTeX4; to appear in PLoS Computational Biolog

Cellular analysis of the action of epigenetics drugs and probes

Small molecule drugs and probes are important tools in drug discovery, pharmacology, and cell biology. This is of course also true for epigenetic inhibitors. Important examples for the use of established epigenetic inhibitors are the study of the mechanistic role of a certain target in a cellular setting or the modulation of a certain phenotype in an approach that aims towards therapeutic application. Alternatively, cellular testing may aim at the validation of a new epigenetic inhibitor in drug discovery approaches. Cellular and eventually animal models provide powerful tools for these different approaches but certain caveats have to be recognized and taken into account. This involves both the selectivity of the pharmacological tool as well as the specificity and the robustness of the cellular system. In this article, we present an overview of different methods that are used to profile and screen for epigenetic agents and comment on their limitations. We describe not only diverse successful case studies of screening approaches using different assay formats, but also some problematic cases, critically discussing selected applications of these systems

FIRE (facilitating implementation of research evidence) : a study protocol

Research evidence underpins best practice, but is not always used in healthcare. The Promoting Action on Research Implementation in Health Services (PARIHS) framework suggests that the nature of evidence, the context in which it is used, and whether those trying to use evidence are helped (or facilitated) affect the use of evidence. Urinary incontinence has a major effect on quality of life of older people, has a high prevalence, and is a key priority within European health and social care policy. Improving continence care has the potential to improve the quality of life for older people and reduce the costs associated with providing incontinence aids

Simplifying Consent for HIV Testing Is Associated with an Increase in HIV Testing and Case Detection in Highest Risk Groups, San Francisco January 2003–June 2007

Populations at highest risk for HIV infection face multiple barriers to HIV testing. To facilitate HIV testing procedures, the San Francisco General Hospital Medical Center eliminated required written patient consent for HIV testing in its medical settings in May 2006. To describe the change in HIV testing rates in different hospital settings and populations after the change in HIV testing policy in the SFDH medical center, we performed an observational study using interrupted time series analysis.Data from all patients aged 18 years and older seen from January 2003 through June 2007 at the San Francisco Department of Public Health (SFDPH) medical care system were included in the analysis. The monthly HIV testing rate per 1000 had patient-visits was calculated for the overall population and stratified by hospital setting, age, sex, race/ethnicity, homelessness status, insurance status and primary language.By June 2007, the average monthly rate of HIV tests per 1000 patient-visits increased 4.38 (CI, 2.17-6.60, p<0.001) over the number predicted if the policy change had not occurred (representing a 44% increase). The monthly average number of new positive HIV tests increased from 8.9 (CI, 6.3-11.5) to 14.9 (CI, 10.6-19.2, p<0.001), representing a 67% increase. Although increases in HIV testing were seen in all populations, populations at highest risk for HIV infection, particularly men, the homeless, and the uninsured experienced the highest increases in monthly HIV testing rates after the policy change.The elimination of the requirement for written consent in May 2006 was associated with a significant and sustained increase in HIV testing rates and HIV case detection in the SFDPH medical center. Populations facing the higher barriers to HIV testing had the highest increases in HIV testing rates and case detection in response to the policy change

Standalone vertex finding in the ATLAS muon spectrometer

A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to bbar b final states, and pp collision data at √s = 7 TeV collected with the ATLAS detector at the LHC during 2011

Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC

Measurements are presented of production properties and couplings of the recently discovered Higgs boson using the decays into boson pairs, H →γ γ, H → Z Z∗ →4l and H →W W∗ →lνlν. The results are based on the complete pp collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at centre-of-mass energies of √s = 7 TeV and √s = 8 TeV, corresponding to an integrated luminosity of about 25 fb−1. Evidence for Higgs boson production through vector-boson fusion is reported. Results of combined fits probing Higgs boson couplings to fermions and bosons, as well as anomalous contributions to loop-induced production and decay modes, are presented. All measurements are consistent with expectations for the Standard Model Higgs boson