93 research outputs found

    Titanium phosphonate oxo-alkoxide "clusters": solution stability and facile hydrolytic transformation into nano titania

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    Titanium (oxo-) alkoxide phosphonate complexes were synthesized using different titanium precursors and tert-butylphosphonic acid (tBPA) as molecular models for interaction between phosphonates and titania surfaces and to investigate the solution stability of these species. Reflux of titanium(IV) ethoxide ortitanium(IV)(diisopropoxide)bis(2,4-pentadionate) withtert-butylphosphonic acid in toluene–ethanolmixture or acetone yielded seven titanium alkoxide phosphonate complexes; [Ti5(m3-O)(m2-O)-(m-HOEt)2(m-OEt)3(m2-OEt)(m3-tBPA)3(m3-HtBPA)(m2-tBPA)2(m2-HtBPA)]3EtOH,1,[Ti4O(mOEt)5(m2OEt)7(m3tBPA)],2,[Ti4(m2O)2(mOEt)2(mHOEt)2(m2tPBA)2(m2HtPBA)6]3EtOH,1, [Ti4O(m-OEt)5(m2-OEt)7-(m3-tBPA)],2,[Ti4(m2-O)2(m-OEt)2(m-HOEt)2(m2-tPBA)2(m2-HtPBA)6]4EtOH,3,[Ti4(m2-O)2(m-OEt)2(m-HOEt)2-(m2-tPBA)2(m2-HtPBA)6]$2EtOH,4,[Ti6(m2-O)(m3-O)2(m2-OEt)5(m-OEt)6(m3-tBPA)3(m3-HtBPA)],5,[Ti4(m-iOPr)4(acac)4(m2-tBPA)4],6 and [Ti5(m4-O)(m2-O)3(m2-OEt)4(m-OEt)6(m-HOEt)(m3-tBPA)]2,7. The binding mode of tBPAtothetitanium oxo-core were either double or triple bridging or a combination of the two. No monodentate or chelating coordination was observed.31P NMR spectrometry of dissolved single crystals indicates that 1 and 5 retain their solid-state structures in solution, the latter even on moderate heating, while 6 and 7 dissolved into several other forms. The complexes were found to be sensitive towards hydrolysis, proceeding in a topotacticfashion with densification of the material into plates and lamellae resulting finally in “core–shell”nanoparticles with a crystalline core (anatase) and an amorphous outer shell upon contact with water at room temperature as observed by HRTEM and AFM analyses.31P NMR data supported degradation after addition of water to solutions of the complexes. Hydrolysis under different conditions affords complex oxide structures of different morphologies

    Noise-dependent bias in quantitative STEM-EMCD experiments revealed by bootstrapping

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    Electron magnetic circular dichroism (EMCD) is a powerful technique for estimating element-specific magnetic moments of materials on nanoscale with the potential to reach atomic resolution in transmission electron microscopes. However, the fundamentally weak EMCD signal strength complicates quantification of magnetic moments, as this requires very high precision, especially in the denominator of the sum rules. Here, we employ a statistical resampling technique known as bootstrapping to an experimental EMCD dataset to produce an empirical estimate of the noise dependent error distribution resulting from application of EMCD sum rules to bcc iron in a 3 beam orientation. We observe clear experimental evidence that noisy EMCD signals preferentially bias the estimation of magnetic moments, further supporting this with error distributions produced by Monte-Carlo simulations. Finally, we propose guidelines for the recognition and minimization of this bias in the estimation of magnetic moments

    Formation of unexpectedly active Ni–Fe oxygen evolution electrocatalysts by physically mixing Ni and Fe oxyhydroxides

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    We present an unusual, yet facile, strategy towards formation of physically mixed Ni–Fe(OxHy) oxygen evolution electrocatalysts. We use in situ X-ray absorption and UV-vis spectroscopy, and high-resolution imaging to demonstrate that physical contact between two inferior Ni(OH)2 and Fe(OOH) catalysts self-assemble into atomically intermixed Ni–Fe catalysts with unexpectedly high activity

    The impact of cardiac comorbidity sequence at baseline and mortality risk in type 2 Diabetes Mellitus: a retrospective population-based cohort study

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    Introduction: The presence of multiple comorbidities increases the risk of all-cause mortality, but the effects of the comorbidity sequence before the baseline date on mortality remain unexplored. This study investigated the relationship between coronary heart disease (CHD), atrial fibrillation (AF) and heart failure (HF) through their sequence of development and the effect on all-cause mortality risk in type 2 diabetes mellitus. Methods: This study included patients with type 2 diabetes mellitus prescribed antidiabetic/cardiovascular medications in public hospitals of Hong Kong between 1 January 2009 and 31 December 2009, with follow-up until death or 31 December 2019. The Cox regression was used to identify comorbidity sequences predicting all-cause mortality in patients with different medication subgroups. Results: A total of 249,291 patients (age: 66.0 ± 12.4 years, 47.4% male) were included. At baseline, 7564, 10,900 and 25,589 patients had AF, HF and CHD, respectively. Over follow-up (3524 ± 1218 days), 85,870 patients died (mortality rate: 35.7 per 1000 person-years). Sulphonylurea users with CHD developing later and insulin users with CHD developing earlier in the disease course had lower mortality risks. Amongst insulin users with two of the three comorbidities, those with CHD with preceding AF (hazard ratio (HR): 3.06, 95% CI: [2.60–3.61], p < 0.001) or HF (HR: 3.84 [3.47–4.24], p < 0.001) had a higher mortality. In users of lipid-lowering agents with all three comorbidities, those with preceding AF had a higher risk of mortality (AF-CHD-HF: HR: 3.22, [2.24–4.61], p < 0.001; AF-HF-CHD: HR: 3.71, [2.66–5.16], p < 0.001). Conclusions: The sequence of comorbidity development affects the risk of all-cause mortality to varying degrees in diabetic patients on different antidiabetic/cardiovascular medications

    The Impact of Cardiac Comorbidity Sequence at Baseline and Mortality Risk in Type 2 Diabetes Mellitus: A Retrospective Population-Based Cohort Study.

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    The presence of multiple comorbidities increases the risk of all-cause mortality, but the effects of the comorbidity sequence before the baseline date on mortality remain unexplored. This study investigated the relationship between coronary heart disease (CHD), atrial fibrillation (AF) and heart failure (HF) through their sequence of development and the effect on all-cause mortality risk in type 2 diabetes mellitus. This study included patients with type 2 diabetes mellitus prescribed antidiabetic/cardiovascular medications in public hospitals of Hong Kong between 1 January 2009 and 31 December 2009, with follow-up until death or 31 December 2019. The Cox regression was used to identify comorbidity sequences predicting all-cause mortality in patients with different medication subgroups. A total of 249,291 patients (age: 66.0 ± 12.4 years, 47.4% male) were included. At baseline, 7564, 10,900 and 25,589 patients had AF, HF and CHD, respectively. Over follow-up (3524 ± 1218 days), 85,870 patients died (mortality rate: 35.7 per 1000 person-years). Sulphonylurea users with CHD developing later and insulin users with CHD developing earlier in the disease course had lower mortality risks. Amongst insulin users with two of the three comorbidities, those with CHD with preceding AF (hazard ratio (HR): 3.06, 95% CI: [2.60-3.61], &lt; 0.001) or HF (HR: 3.84 [3.47-4.24], &lt; 0.001) had a higher mortality. In users of lipid-lowering agents with all three comorbidities, those with preceding AF had a higher risk of mortality (AF-CHD-HF: HR: 3.22, [2.24-4.61], &lt; 0.001; AF-HF-CHD: HR: 3.71, [2.66-5.16], &lt; 0.001). The sequence of comorbidity development affects the risk of all-cause mortality to varying degrees in diabetic patients on different antidiabetic/cardiovascular medications

    Secular trends of health care resource utilization and costs between Brugada syndrome and congenital long QT syndrome: A territory‐wide study

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    Background Health care resource utilization (HCRU) and costs are important metrics of health care burden, but they have rarely been explored in the setting of cardiac ion channelopathies. Hypothesis This study tested the hypothesis that attendance-related HCRUs and costs differed between patients with Brugada syndrome (BrS) and congenital long QT syndrome (LQTS). Methods This was a retrospective cohort study of consecutive BrS and LQTS patients at public hospitals or clinics in Hong Kong, China. HCRUs and costs (in USD) for Accident and Emergency (A&E), inpatient, general outpatient and specialist outpatient attendances were analyzed between 2001 and 2019 at the cohort level. Comparisons were made using incidence rate ratios (IRRs [95% confidence intervals]). Results Over the 19-year period, 516 BrS (median age of initial presentation: 51 [interquartile range: 38−61] years, 92% male) and 134 LQTS (median age of initial presentation: 21 [9−44] years, 32% male) patients were included. Compared to LQTS patients, BrS patients had lower total costs (2 008 126 [2 007 622−2 008 629] vs. 2 343 864 [2 342 828−2 344 900]; IRR: 0.857 [0.855−0.858]), higher costs for A&E attendances (83 113 [83 048−83 177] vs. 70 604 [70 487−70 721]; IRR: 1.177 [1.165−1.189]) and general outpatient services (2,176 [2,166−2,187] vs. 921 [908−935]; IRR: 2.363 [2.187−2.552]), but lower costs for inpatient stay (1 391 624 [1 391 359−1 391 889] vs. 1 713 742 [1 713 166−1 714 319]; IRR: 0.812 [0.810−0.814]) and lower costs for specialist outpatient services (531 213 [531 049−531 376] vs. 558 597 [558268−558926]; IRR: 0.951 [0.947−0.9550]). Conclusions Overall, BrS patients consume 14% less health care resources compared to LQTS patients in terms of attendance costs. BrS patients require more A&E and general outpatient services, but less inpatient and specialist outpatient services than LQTS patients
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