7 research outputs found
Perchlorate‐Intercalated Layered Double Hydroxide of Ca and Al: Synthesis, Structure Refinement, and Reversible Dehydration
No full textInteraction of Pristine Hydrocalumite-Like Layered Double Hydroxides with Carbon Dioxide
No full textSynthesis, Polytypism, and Dehydration Behaviour of Nitrate-Intercalated Layered Double Hydroxides of Ca and Al
No full textRapid precipitation of the hydroxide phase from a mixed metal nitrate solution comprising Ca2+ and Al3+ ions leads to the formation of a one-layered hexagonal polytype of [Ca-Al] layered double hydroxide. In contrast, slow precipitation results in a three-layered polytype of rhombohedral symmetry. Both polytypes comprise a stacking of positively charged metal hydroxide layers having the composition [Ca2Al(OH)6(H2O)2]+. The Ca2+ ions are seven coordinated with water molecules providing the seventh coordination. In the absence of any prior knowledge of the structure of the 1H polytype, translationengleiche and klassengleiche graphs were used to arrive at the space group and atom positions of the 1H polytype. Rietveld refinements of the structures of the two polytypes show that nitrate ions are intercalated in the interlayer gallery with its molecular plane inclined to the metal hydroxide layer. The angle of inclination in the 1H polytype (∼61°) is greater than that in the 3R polytype (∼30°). When the 1H polytype is completely dehydrated, the metal hydroxide layers undergo a rigid translation relative to one another resulting in (i) a 1H → 3R interpolytype transition, and (ii) the grafting of the nitrate ion to the metal hydroxide layer to satisfy the seventh coordination of the Ca2+ ion. The as-prepared 3R polytype has a mixed anion interlayer comprising nitrate and hydroxyl ions. On heating, this phase progressively loses crystallinity before decomposition
Interaction of Pristine Hydrocalumite-Like Layered Double Hydroxides with Carbon Dioxide
No full textThe layered double
hydroxides (LDHs) of Ca2+ and trivalent
cations, Al3+ and Fe3+, are single-source precursors
to generate supported CaO, which picks up CO2 from the
gas phase in the temperature range 350–550 °C. The supports
are ternary oxides, mayenite, and Ca2Fe2O5. The uptake capacity of the Fe3+-containing LDH
at 1.9 mmol g–1 is two times the capacity of the
Al3+-containing LDH. The product of CO2 uptake
is calcite CaCO3. It is observed that the intercalated
chloride ions reduce the thermal penalty by inducing the early decomposition
of CaCO3. In the case of the chloride-intercalated LDHs
of Ca2+ and Fe3+, the CaCO3 formed
is completely decomposed at 900 °C. This is in contrast with
the CaCO3 formed from bare CaO, which shows no sign of
decomposition at 900 °C under similar conditions. This work shows
that the hydrocalumite-like LDHs are candidate materials for CO2 mineralization
Relationship Between Severity of Ischemia and Coronary Artery Disease for Different Stress Test Modalities in the ISCHEMIA Trial
No full textBACKGROUND: The relationship between the extent and severity of stress-induced ischemia and the extent and severity of anatomic coronary artery disease (CAD) in patients with obstructive CAD is multifactorial and includes the intensity of stress achieved, type of testing used, presence and extent of prior infarction, collateral blood flow, plaque characteristics, microvascular disease, coronary vasomotor tone, and genetic factors. Among chronic coronary disease participants with site-determined moderate or severe ischemia, we investigated associations between ischemia severity on stress testing and the extent of CAD on coronary computed tomography angiography. METHODS: Clinically indicated stress testing included nuclear imaging, echocardiography, cardiac magnetic resonance imaging, or nonimaging exercise tolerance test. Among those with preserved renal function who underwent coronary computed tomography angiography, we examined relationships between ischemia and CAD by coronary computed tomography angiography, overall, and by stress test modality, regardless of subsequent randomization. Core laboratories categorized ischemia as severe, moderate, mild, or none, while the extent and severity of anatomic CAD were categorized based on the modified Duke prognostic index. RESULTS: Among 3601 participants with interpretable stress tests and coronary computed tomography angiography, ischemia severity was weakly associated with CAD extent/severity (r=0.27), with modest variability in strength of association by modality: nuclear (n=1532; r=0.40), echocardiography (n=827; r=0.15), cardiac magnetic resonance imaging (n=108; r=0.31), and exercise tolerance test (n=1134; r=0.18). The extent of infarction on nuclear imaging and echocardiography was weakly associated with CAD extent/severity. CONCLUSIONS: Overall, ischemia severity on stress testing showed weak to moderate associations with the anatomic extent of CAD in this cohort with moderate or severe ischemia on local interpretation and controlled symptoms
Neuromuscular disease genetics in under-represented populations: increasing data diversity
No full text\ua9 The Author(s) 2023. Published by Oxford University Press on behalf of the Guarantors of Brain. Neuromuscular diseases (NMDs) affect ∼15 million people globally. In high income settings DNA-based diagnosis has transformed care pathways and led to gene-specific therapies. However, most affected families are in low-to-middle income countries (LMICs) with limited access to DNA-based diagnosis. Most (86%) published genetic data is derived from European ancestry. This marked genetic data inequality hampers understanding of genetic diversity and hinders accurate genetic diagnosis in all income settings. We developed a cloud-based transcontinental partnership to build diverse, deeply-phenotyped and genetically characterized cohorts to improve genetic architecture knowledge, and potentially advance diagnosis and clinical management. We connected 18 centres in Brazil, India, South Africa, Turkey, Zambia, Netherlands and the UK. We co-developed a cloud-based data solution and trained 17 international neurology fellows in clinical genomic data interpretation. Single gene and whole exome data were analysed via a bespoke bioinformatics pipeline and reviewed alongside clinical and phenotypic data in global webinars to inform genetic outcome decisions. We recruited 6001 participants in the first 43 months. Initial genetic analyses \u27solved\u27 or \u27possibly solved\u27 ∼56% probands overall. In-depth genetic data review of the four commonest clinical categories (limb girdle muscular dystrophy, inherited peripheral neuropathies, congenital myopathy/muscular dystrophies and Duchenne/Becker muscular dystrophy) delivered a ∼59% \u27solved\u27 and ∼13% \u27possibly solved\u27 outcome. Almost 29% of disease causing variants were novel, increasing diverse pathogenic variant knowledge. Unsolved participants represent a new discovery cohort. The dataset provides a large resource from under-represented populations for genetic and translational research. In conclusion, we established a remote transcontinental partnership to assess genetic architecture of NMDs across diverse populations. It supported DNA-based diagnosis, potentially enabling genetic counselling, care pathways and eligibility for gene-specific trials. Similar virtual partnerships could be adopted by other areas of global genomic neurological practice to reduce genetic data inequality and benefit patients globally
Land-use emissions play a critical role in landbased mitigation for Paris climate targets
No full textScenarios that limit global warming to below 2 °C by 2100 assume significant land-use
change to support large-scale carbon dioxide (CO2) removal from the atmosphere by
afforestation/reforestation, avoided deforestation, and Biomass Energy with Carbon Capture
and Storage (BECCS). The more ambitious mitigation scenarios require even greater land
area for mitigation and/or earlier adoption of CO2 removal strategies. Here we show that
additional land-use change to meet a 1.5 °C climate change target could result in net losses of
carbon from the land. The effectiveness of BECCS strongly depends on several assumptions
related to the choice of biomass, the fate of initial above ground biomass, and the fossil-fuel
emissions offset in the energy system. Depending on these factors, carbon removed from the
atmosphere through BECCS could easily be offset by losses due to land-use change. If BECCS
involves replacing high-carbon content ecosystems with crops, then forest-based mitigation
could be more efficient for atmospheric CO2 removal than BECCS
