21 research outputs found
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Hydrogen production via a sulfur-sulfur thermochemical water-splitting cycle
Thermochemical water splitting cycles have been conceptualized and researched for over half a century, yet to this day none are commercially viable. The heavily studied Sulfur-Iodine cycle has been stalled in the early development stage due to a difficult HI-H₂O separation step and material compatibility issues. In an effort to avoid the azeotropic HI-H₂O mixture, an imidazolium-based ionic liquid was used as a reaction medium instead of water. Ionic liquids were selected based on their high solubility for SO₂, I₂, and tunable miscibility with water. The initial low temperature step of the Sulfur-Iodine cycle was successfully carried out in ionic liquid reaction medium. Kinetics of the reaction were investigated by I₂ colorimetry. The reaction also evolved H₂S gas, which led to the conceptual idea of a new Sulfur-Sulfur thermochemical cycle, shown below:4I₂(l)+4SO₂(l)+8H₂O(l)↔4H₂SO₄(l)+ 8HI(l)8HI(l)+H₂SO₄(l)↔ H₂S(g)+4H₂O(l)+4I₂(l)3H₂SO₄(g)↔ 3H₂O(g)+3SO₂(g)+1½O₂(g)H₂S(g)+2H₂O(g)↔ SO₂(g)+3H₂(g)The critical step in the Sulfur-Sulfur cycle is the steam reformation of H₂S. This highly endothermic step is shown to successfully occur at temperatures in excess of 800˚C in the presence of a molybdenum catalyst. A parametric study varying the H₂O:H₂S ratio, temperature, and residence time in a simple tubular quartz reactor was carried out and Arrhenius parameters were estimated.
All reactive steps of the Sulfur-Sulfur cycle have been either demonstrated previously or demonstrated in this work. A theoretical heat-to-hydrogen thermal efficiency is estimated to be 55% at a hot temperature of 1100 K and 59% at 2000 K. As a highly efficient, all-fluid based thermochemical cycle, the Sulfur-Sulfur cycle has great potential for feasible process implementation for the transformation of high quality heat to chemical energy
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Reactive phase change materials for enhanced thermal energy storage
Effective storage and release of low-to-moderate temperature thermal energy (e.g. solar thermal or geothermal) could be transformational for applications such as space heating/cooling, domestic hot water, or off-grid cooking. Good candidates for thermal energy storage in this temperature range include latent heat storage (LHS) systems and thermochemical energy storage (TCES) systems using reversible salt-hydrate dehydration reactions. Here we propose that an energy storage system by use of magnesium nitrate hexahydrate can potentially improve upon independent TCES or LHS systems by utilizing both the thermochemical hydration reaction and the latent heat available through the solid-liquid phase change of one magnesium nitrate hydrate eutectic. This chemistry is investigated through TGA/DSC analysis and shows a total energy density of approximately 1170±94 kJ/kg when dehydrating the material up to 145°C. Reversible latent heat cycling at a eutectic melting temperature of 130°C is shown by the DSC signal and estimated to be on the order of 115±9.2 kJ/kg—a 10% increase over the thermochemical energy storage alone. Although the latent energy release was found to decrease slightly over several cycles, the mass was found to stabilize near an asymptotic value corresponding to the published eutectic composition. These results suggest the concept of reactive phase change materials could be a promising solution to increasing volumetric stored energy density
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Genetically Predicted Glucose-Dependent Insulinotropic Polypeptide (GIP) Levels and Cardiovascular Disease Risk Are Driven by Distinct Causal Variants in the GIPR Region.
There is considerable interest in GIPR agonism to enhance the insulinotropic and extrapancreatic effects of GIP, thereby improving glycemic and weight control in type 2 diabetes (T2D) and obesity. Recent genetic epidemiological evidence has implicated higher GIPR-mediated GIP levels in raising coronary artery disease (CAD) risk, a potential safety concern for GIPR agonism. We therefore aimed to quantitatively assess whether the association between higher GIPR-mediated fasting GIP levels and CAD risk is mediated via GIPR or is instead the result of linkage disequilibrium (LD) confounding between variants at the GIPR locus. Using Bayesian multitrait colocalization, we identified a GIPR missense variant, rs1800437 (G allele; E354), as the putatively causal variant shared among fasting GIP levels, glycemic traits, and adiposity-related traits (posterior probability for colocalization [PPcoloc] > 0.97; PP explained by the candidate variant [PPexplained] = 1) that was independent from a cluster of CAD and lipid traits driven by a known missense variant in APOE (rs7412; distance to E354 ∼770 Kb; R 2 with E354 = 0.004; PPcoloc > 0.99; PPexplained = 1). Further, conditioning the association between E354 and CAD on the residual LD with rs7412, we observed slight attenuation in association, but it remained significant (odds ratio [OR] per copy of E354 after adjustment 1.03; 95% CI 1.02, 1.04; P = 0.003). Instead, E354's association with CAD was completely attenuated when conditioning on an additional established CAD signal, rs1964272 (R 2 with E354 = 0.27), an intronic variant in SNRPD2 (OR for E354 after adjustment for rs1964272: 1.01; 95% CI 0.99, 1.03; P = 0.06). We demonstrate that associations with GIP and anthropometric and glycemic traits are driven by genetic signals distinct from those driving CAD and lipid traits in the GIPR region and that higher E354-mediated fasting GIP levels are not associated with CAD risk. These findings provide evidence that the inclusion of GIPR agonism in dual GIPR/GLP1R agonists could potentiate the protective effect of GLP-1 agonists on diabetes without undue CAD risk, an aspect that has yet to be assessed in clinical trials
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Al2O3 coated LiCoO2 as cathode for high-capacity and long-cycling Li-ion batteries
Lithium-ion batteries (LIBs) as energy storage devices play an important role in all aspects of our life. The increasing energy demand of the society requires LIBs with higher energy density and better performance. We here develop a new and easy-to-scaleup sol-gel method to coat a surface protection layer on commercial LiCoO2 cathode. We demonstrate that a proper thickness can improve the cycling life with a higher cut-off potential (4.5 V), larger energy capacity (180 mAh/g at 0.5C) and better energy density (35% more compared to non-coated LiCoO2). The mechanism of the protection layer is also revealed by a combination of electron microscopy and synchrotron X-ray spectroscopy. (C) 2018 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved
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Solar Thermochemical Energy Storage Through Carbonation Cycles of SrCO₃/SrO Supported on SrZrO₃
Solar thermochemical energy storage has enormous potential for enabling cost-effective concentrated solar power (CSP). A thermochemical storage system based on a SrO/SrCO₃ carbonation cycle offers the ability to store and release high temperature (≈1200 °C) heat. The energy density of SrCO₃/SrO systems supported by zirconia-based sintering inhibitors was investigated for 15 cycles of exothermic carbonation at 1150 °C followed by decomposition at 1235 °C. A sample with 40 wt % of SrO supported by yttria-stabilized zirconia (YSZ) shows good energy storage stability at 1450 MJ m⁻³ over fifteen cycles at the same cycling temperatures. After further testing over 45 cycles, a decrease in energy storage capacity to 1260 MJ m⁻³ is observed during the final cycle. The decrease is due to slowing carbonation kinetics, and the original value of energy density may be obtained by lengthening the carbonation steps.Keywords: energy storage, strontium oxide, concentrated solar power, reactive stabilit
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Genetic architecture of host proteins involved in SARS-CoV-2 infection
Funder: Medical Research CouncilAbstract: Understanding the genetic architecture of host proteins interacting with SARS-CoV-2 or mediating the maladaptive host response to COVID-19 can help to identify new or repurpose existing drugs targeting those proteins. We present a genetic discovery study of 179 such host proteins among 10,708 individuals using an aptamer-based technique. We identify 220 host DNA sequence variants acting in cis (MAF 0.01-49.9%) and explaining 0.3-70.9% of the variance of 97 of these proteins, including 45 with no previously known protein quantitative trait loci (pQTL) and 38 encoding current drug targets. Systematic characterization of pQTLs across the phenome identified protein-drug-disease links and evidence that putative viral interaction partners such as MARK3 affect immune response. Our results accelerate the evaluation and prioritization of new drug development programmes and repurposing of trials to prevent, treat or reduce adverse outcomes. Rapid sharing and detailed interrogation of results is facilitated through an interactive webserver (https://omicscience.org/apps/covidpgwas/)
Author Correction: Genetic architecture of host proteins involved in SARS-CoV-2 infection.
A Correction to this paper has been published: https://doi.org/10.1038/s41467-021-21370-6</jats:p
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Rare and common genetic determinants of metabolic individuality and their effects on human health
Garrod’s concept of “chemical individuality” has contributed to comprehension of molecular origins of human diseases. Untargeted high throughput metabolomic technologies provide an in-depth snapshot of human metabolism at scale. Here we studied the genetic architecture of the human plasma metabolome using 913 metabolites assayed in 19,994 individuals. We identified 2,599 variant-metabolite associations (P<1.25x10-11) within 330 genomic regions, with rare variants (MAF≤1%) explaining 9.4% of associations. Jointly modelling metabolites in each region, we identified 423 regional, co-regulated, variant-metabolite clusters (Genetically Influenced Metabotypes). We assigned causal genes for 62.4% of GIMs, providing new insights into fundamental metabolite physiology and their clinical relevance, including metabolite guided discovery of potential adverse drug effects (DPYD, SRD5A2). We show strong enrichment of Inborn Errors of Metabolism (IEM)-causing genes, with examples of metabolite associations and clinical phenotypes of non-pathogenic variant carriers matching characteristics of IEMs. Systematic, phenotypic follow-up of metabolite-specific genetic scores revealed multiple potential aetiological relationships