149 research outputs found
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Impact of CO2 Impurities on Storage Performance and Assurance - Report on Tasks 3 and 4 (Geochemistry) Prepared for: CO2 Capture Project (Phase III)
This document presents the results of Tasks 3 and 4 out of 5 tasks, focusing on the geochemical impacts of impurities in the CO2 stream. Tasks 1 and 2 were dedicated to examining the effects on flow behavior. The impurities primarily consist of N2, O2, and Ar, with several minor reactive species potentially added, including CO, H2, SOx, and other trace gases. The research methodology involved laboratory autoclave experiments combined with geochemical numerical modeling.
The autoclave utilized in the experiments is a 250-ml reactor capable of withstanding temperatures up to 150Β°C and pressures up to 400 bars, simulating conditions observed in reservoirs at depths of up to 12,000 ft. Pressure and temperature were automatically controlled by a computer, and the system allowed for water sampling during the experiments. Typically, 10 to 15 samples of the solution were collected during each experiment, which lasted 5 to 10 days.
Rock samples were exposed to either a supercritical mixture of CO2 and O2 (generally 3.5% molar) or pure supercritical CO2, filling approximately half of the reactor cell. The other half of the cell contained a single core fragment or several large fragments (~8g total) submerged in approximately 140 ml of synthetic brine (~1.88 mol NaCl, corresponding to a TDS of 100,000-110,000 mg/L).
The study analyzed three types of clastic rock samples:
1. A "dirty sandstone" of Miocene age obtained from a deep well in the shallow offshore region off the Texas coast.
2. A relatively clean sandstone from the Cretaceous-age Cardium Formation in Alberta.
3. A chlorite-rich sandstone from the Tuscaloosa Formation in Mississippi, sourced from the Cranfield site, which has been extensively studied by BEG for several years.Bureau of Economic Geolog
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Impact of CO2 Impurities on Storage Performance and Assurance -Report on Task 5 (Integration of Flow and Geochemistry) and Final Report Prepared for: CO2 Capture Project (Phase III)
A key impediment to carbon capture and storage is the cost of CO2 capture, particularly for conventional power plants whose flue gas is dominated by gases other than CO2. Waste gas streams from power plants that use novel technologies (such as oxyfuel, the focus of this work) can circumvent the capture step thanks to their CO2-rich composition (CO2 > 90%), but at the expense of CO2 stream purity. In addition to CO2, two non-reactive gases make up the bulk of impurities: N2 and Ar. O2 is the most commonly cited reactive gas, with molar concentrations ranging from 5%. Other minor species may also be present.
Relatively high purity levels must be achieved to avoid compression and complications in pipeline transportation (two-phase flow) and, potentially, subsurface impacts. This work investigates the latter, which, in turn, informs techno-economic assessments of capture and transportation economics. Subsurface impacts of an impure CO2 stream could be twofold: (1) complicate flow behavior and reduce static capacity due to density and viscosity differences and (2) undermine reservoir and top seal integrity due to reactions with reactive species (O2, CO, SOx).
To address the first issue, we conducted a desktop study using a numerical modeling tool and performed laboratory experiments to determine the actual viscosity and density of the mixtures. Information on the solubility of these various mixture components in the aqueous phase under various pressure, temperature, and salinity conditions was also collected.
An important observation controlling all study results was that the viscosity and density of the mixtures considered are lower than those of pure CO2 at the same temperatures and pressures. It follows that a plume of CO2 with impurities, moving updip with no barrier, will migrate farther from the point of injection but will be trapped through residual saturation sooner than a plume of pure CO2, possibly enhancing dissolution primarily because it is exposed to more rock/brine volume. However, a larger plume means that a larger area must be defined and monitored for leakage pathways, such as faults and wells, but the faster trapping translates into a shorter monitoring period. Equally important is that contrasts of viscosity and density between pure CO2 and a CO2 mixture decrease with depth, suggesting that differences in flow behavior and storage capacity are proportionally reduced with depth.Bureau of Economic Geolog
Capturing the essence of folding and functions of biomolecules using Coarse-Grained Models
The distances over which biological molecules and their complexes can
function range from a few nanometres, in the case of folded structures, to
millimetres, for example during chromosome organization. Describing phenomena
that cover such diverse length, and also time scales, requires models that
capture the underlying physics for the particular length scale of interest.
Theoretical ideas, in particular, concepts from polymer physics, have guided
the development of coarse-grained models to study folding of DNA, RNA, and
proteins. More recently, such models and their variants have been applied to
the functions of biological nanomachines. Simulations using coarse-grained
models are now poised to address a wide range of problems in biology.Comment: 37 pages, 8 figure
Tightening the knot in phytochrome by single molecule atomic force microscopy
A growing number of proteins have been shown to adopt knotted folds. Yet the
biological roles and biophysical properties of these knots remain poorly
understood. We have used protein engineering and atomic force microscopy to
explore single-molecule mechanics of the figure-of-eight knot in the
chromophore-binding domain of the red/far red photoreceptor, phytochrome. Under
load, apo phytochrome unfolds at forces of ~47 pN, while phytochrome carrying
its covalently bound tetrapyrrole chromophore unfolds at ~73 pN. These forces
are among the lowest measured in mechanical protein unfolding, hence the
presence of the knot does not automatically indicate a super-stable protein.
Our experiments reveal a stable intermediate along the mechanical unfolding
pathway, reflecting sequential unfolding of two distinct subdomains in
phytochrome, potentially the GAF and PAS domains. For the first time, our
experiments allow direct determination of knot size under load. In the unfolded
chain, the tightened knot is reduced to 17 amino acids, resulting in apparent
shortening of the polypeptide chain by 6.2 nm. Steered molecular dynamics
simulations corroborate this number. Finally, we found that covalent
phytochrome dimers created for these experiments retain characteristic
photoreversibility, unexpectedly arguing against dramatic rearrangement of the
native GAF dimer interface upon photoconversion.Comment: 12 pages plus five figures; has been submitted to Biophysical J.
Replacement on 9/16 is ONLY to correct a typo in the meta data; the uploaded
file is identical to first versio
Committee autonomy in parliamentary systems β coalition logic or congressional rationales?
The Institutions of Politics; Design, Workings, and implications ( do not use, ended 1-1-2020
Detecting intratumoral heterogeneity of EGFR activity by liposome-based in vivo transfection of a fluorescent biosensor
Despite decades of research in the epidermal growth factor receptor (EGFR) signalling field, and many targeted anti-cancer drugs that have been tested clinically, the success rate for these agents in the clinic is low, particularly in terms of the improvement of overall survival. Intratumoral heterogeneity is proposed as a major mechanism underlying treatment failure of these molecule-targeted agents. Here we highlight the application of fluorescence lifetime microscopy (FLIM)-based biosensing to demonstrate intratumoral heterogeneity of EGFR activity. For sensing EGFR activity in cells, we used a genetically encoded CrkII-based biosensor which undergoes conformational changes upon tyrosine-221 phosphorylation by EGFR. We transfected this biosensor into EGFR-positive tumour cells using targeted lipopolyplexes bearing EGFR-binding peptides at their surfaces. In a murine model of basal-like breast cancer, we demonstrated a significant degree of intratumoral heterogeneity in EGFR activity, as well as the pharmacodynamic effect of a radionuclide-labeled EGFR inhibitor in situ. Furthermore, a significant correlation between high EGFR activity in tumour cells and macrophage-tumour cell proximity was found to in part account for the intratumoral heterogeneity in EGFR activity observed. The same effect of macrophage infiltrate on EGFR activation was also seen in a colorectal cancer xenograft. In contrast, a non-small cell lung cancer xenograft expressing a constitutively active EGFR conformational mutant exhibited macrophage proximity-independent EGFR activity. Our study validates the use of this methodology to monitor therapeutic response in terms of EGFR activity. In addition, we found iNOS gene induction in macrophages that are cultured in tumour cell-conditioned media as well as an iNOS activity-dependent increase in EGFR activity in tumour cells. These findings point towards an immune microenvironment-mediated regulation that gives rise to the observed intratumoral heterogeneity of EGFR signalling activity in tumour cells in vivo
Extracellular Heat Shock Protein (Hsp)70 and Hsp90Ξ± Assist in Matrix Metalloproteinase-2 Activation and Breast Cancer Cell Migration and Invasion
Breast cancer is second only to lung cancer in cancer-related deaths in women, and the majority of these deaths are caused by metastases. Obtaining a better understanding of migration and invasion, two early steps in metastasis, is critical for the development of treatments that inhibit breast cancer metastasis. In a functional proteomic screen for proteins required for invasion, extracellular heat shock protein 90 alpha (Hsp90Ξ±) was identified and shown to activate matrix metalloproteinase 2 (MMP-2). The mechanism of MMP-2 activation by Hsp90Ξ± is unknown. Intracellular Hsp90Ξ± commonly functions with a complex of co-chaperones, leading to our hypothesis that Hsp90Ξ± functions similarly outside of the cell. In this study, we show that a complex of co-chaperones outside of breast cancer cells assists Hsp90Ξ± mediated activation of MMP-2. We demonstrate that the co-chaperones Hsp70, Hop, Hsp40, and p23 are present outside of breast cancer cells and co-immunoprecipitate with Hsp90Ξ± in vitro and in breast cancer conditioned media. These co-chaperones also increase the association of Hsp90Ξ± and MMP-2 in vitro. This co-chaperone complex enhances Hsp90Ξ±-mediated activation of MMP-2 in vitro, while inhibition of Hsp70 in conditioned media reduces this activation and decreases cancer cell migration and invasion. Together, these findings support a model in which MMP-2 activation by an extracellular co-chaperone complex mediated by Hsp90Ξ± increases breast cancer cell migration and invasion. Our studies provide insight into a novel pathway for MMP-2 activation and suggest Hsp70 as an additional extracellular target for anti-metastatic drug development
Corresponding Functional Dynamics across the Hsp90 Chaperone Family: Insights from a Multiscale Analysis of MD Simulations
Understanding how local protein modifications, such as binding small-molecule ligands, can trigger and regulate large-scale motions of large protein domains is a major open issue in molecular biology. We address various aspects of this problem by analyzing and comparing atomistic simulations of Hsp90 family representatives for which crystal structures of the full length protein are available: mammalian Grp94, yeast Hsp90 and E.coli HtpG. These chaperones are studied in complex with the natural ligands ATP, ADP and in the Apo state. Common key aspects of their functional dynamics are elucidated with a novel multi-scale comparison of their internal dynamics. Starting from the atomic resolution investigation of internal fluctuations and geometric strain patterns, a novel analysis of domain dynamics is developed. The results reveal that the ligand-dependent structural modulations mostly consist of relative rigid-like movements of a limited number of quasi-rigid domains, shared by the three proteins. Two common primary hinges for such movements are identified. The first hinge, whose functional role has been demonstrated by several experimental approaches, is located at the boundary between the N-terminal and Middle-domains. The second hinge is located at the end of a three-helix bundle in the Middle-domain and unfolds/unpacks going from the ATP- to the ADP-state. This latter site could represent a promising novel druggable allosteric site common to all chaperones
Probing Molecular Mechanisms of the Hsp90 Chaperone: Biophysical Modeling Identifies Key Regulators of Functional Dynamics
Deciphering functional mechanisms of the Hsp90 chaperone machinery is an important objective in cancer biology aiming to facilitate discovery of targeted anti-cancer therapies. Despite significant advances in understanding structure and function of molecular chaperones, organizing molecular principles that control the relationship between conformational diversity and functional mechanisms of the Hsp90 activity lack a sufficient quantitative characterization. We combined molecular dynamics simulations, principal component analysis, the energy landscape model and structure-functional analysis of Hsp90 regulatory interactions to systematically investigate functional dynamics of the molecular chaperone. This approach has identified a network of conserved regions common to the Hsp90 chaperones that could play a universal role in coordinating functional dynamics, principal collective motions and allosteric signaling of Hsp90. We have found that these functional motifs may be utilized by the molecular chaperone machinery to act collectively as central regulators of Hsp90 dynamics and activity, including the inter-domain communications, control of ATP hydrolysis, and protein client binding. These findings have provided support to a long-standing assertion that allosteric regulation and catalysis may have emerged via common evolutionary routes. The interaction networks regulating functional motions of Hsp90 may be determined by the inherent structural architecture of the molecular chaperone. At the same time, the thermodynamics-based βconformational selectionβ of functional states is likely to be activated based on the nature of the binding partner. This mechanistic model of Hsp90 dynamics and function is consistent with the notion that allosteric networks orchestrating cooperative protein motions can be formed by evolutionary conserved and sparsely connected residue clusters. Hence, allosteric signaling through a small network of distantly connected residue clusters may be a rather general functional requirement encoded across molecular chaperones. The obtained insights may be useful in guiding discovery of allosteric Hsp90 inhibitors targeting protein interfaces with co-chaperones and protein binding clients
Self-Reported Wisdom and Happiness: An Empirical Investigation
Possible tensions between wisdom and happiness have been extensively debated in philosophy. Some regard wisdom as the 'supreme part of happiness', whereas other think that a more accurate and wiser view on reality might reduce happiness. Analyzing a Dutch internet survey of 7037 respondents, we discovered that wisdom and happiness were modestly positively related. Wisdom, measured with the Three-Dimensional Wisdom Scale (3D-WS), explained 9.2% of the variation in hedonic happiness. The correlation with the reflective dimension of wisdom was the strongest. In addition, wisdom was more important for happiness among adults with only an elementary education. Our results suggest that happiness and wisdom do not conflict
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