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- 2019
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Tidskriftsartikel (refereegranskat)
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| 5. |
- Pantazis, N, et al.
(författare)
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Determining the likely place of HIV acquisition for migrants in Europe combining subject-specific information and biomarkers data
- 2019
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Ingår i: Statistical methods in medical research. - : SAGE Publications. - 1477-0334 .- 0962-2802. ; 28:7, s. 1979-1997
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Tidskriftsartikel (refereegranskat)abstract
- In most HIV-positive individuals, infection time is only known to lie between the time an individual started being at risk for HIV and diagnosis time. However, a more accurate estimate of infection time is very important in certain cases. For example, one of the objectives of the Advancing Migrant Access to Health Services in Europe (aMASE) study was to determine if HIV-positive migrants, diagnosed in Europe, were infected pre- or post-migration. We propose a method to derive subject-specific estimates of unknown infection times using information from HIV biomarkers’ measurements, demographic, clinical, and behavioral data. We assume that CD4 cell count (CD4) and HIV-RNA viral load trends after HIV infection follow a bivariate linear mixed model. Using post-diagnosis CD4 and viral load measurements and applying the Bayes’ rule, we derived the posterior distribution of the HIV infection time, whereas the prior distribution was informed by AIDS status at diagnosis and behavioral data. Parameters of the CD4–viral load and time-to-AIDS models were estimated using data from a large study of individuals with known HIV infection times (CASCADE). Simulations showed substantial predictive ability (e.g. 84% of the infections were correctly classified as pre- or post-migration). Application to the aMASE study ( n = 2009) showed that 47% of African migrants and 67% to 72% of migrants from other regions were most likely infected post-migration. Applying a Bayesian method based on bivariate modeling of CD4 and viral load, and subject-specific information, we found that the majority of HIV-positive migrants in aMASE were most likely infected after their migration to Europe.
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| 6. |
- Drake, Thomas M., et al.
(författare)
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Outcomes following small bowel obstruction due to malignancy in the national audit of small bowel obstruction
- 2019
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Ingår i: European Journal of Surgical Oncology. - : Elsevier BV. - 0748-7983 .- 1532-2157. ; 45:12, s. 2319-2324
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Tidskriftsartikel (refereegranskat)abstract
- © 2019 Elsevier Ltd, BASO ~ The Association for Cancer Surgery, and the European Society of Surgical Oncology Introduction: Patients with cancer who develop small bowel obstruction are at high risk of malnutrition and morbidity following compromise of gastrointestinal tract continuity. This study aimed to characterise current management and outcomes following malignant small bowel obstruction. Methods: A prospective, multicentre cohort study of patients with small bowel obstruction who presented to UK hospitals between 16th January and 13th March 2017. Patients who presented with small bowel obstruction due to primary tumours of the intestine (excluding left-sided colonic tumours) or disseminated intra-abdominal malignancy were included. Outcomes included 30-day mortality and in-hospital complications. Cox-proportional hazards models were used to generate adjusted effects estimates, which are presented as hazard ratios (HR) alongside the corresponding 95% confidence interval (95% CI). The threshold for statistical significance was set at the level of P ≤ 0.05 a-priori. Results: 205 patients with malignant small bowel obstruction presented to emergency surgery services during the study period. Of these patients, 50 had obstruction due to right sided colon cancer, 143 due to disseminated intraabdominal malignancy, 10 had primary tumours of the small bowel and 2 patients had gastrointestinal stromal tumours. In total 100 out of 205 patients underwent a surgical intervention for obstruction. 30-day in-hospital mortality rate was 11.3% for those with primary tumours and 19.6% for those with disseminated malignancy. Severe risk of malnutrition was an independent predictor for poor mortality in this cohort (adjusted HR 16.18, 95% CI 1.86 to 140.84, p = 0.012). Patients with right-sided colon cancer had high rates of morbidity. Conclusions: Mortality rates were high in patients with disseminated malignancy and in those with right sided colon cancer. Further research should identify optimal management strategy to reduce morbidity for these patient groups.
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- Yu, Young-Sang, et al.
(författare)
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Three-dimensional localization of nanoscale battery reactions using soft X-ray tomography
- 2018
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Ingår i: Nature Communications. - : NATURE PUBLISHING GROUP. - 2041-1723. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Battery function is determined by the efficiency and reversibility of the electrochemical phase transformations at solid electrodes. The microscopic tools available to study the chemical states of matter with the required spatial resolution and chemical specificity are intrinsically limited when studying complex architectures by their reliance on two-dimensional projections of thick material. Here, we report the development of soft X-ray ptychographic tomography, which resolves chemical states in three dimensions at 11 nm spatial resolution. We study an ensemble of nano-plates of lithium iron phosphate extracted from a battery electrode at 50% state of charge. Using a set of nanoscale tomograms, we quantify the electrochemical state and resolve phase boundaries throughout the volume of individual nanoparticles. These observations reveal multiple reaction points, intra-particle heterogeneity, and size effects that highlight the importance of multi-dimensional analytical tools in providing novel insight to the design of the next generation of high-performance devices.
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| 11. |
- Jin, Yanting, et al.
(författare)
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Understanding Fluoroethylene Carbonate and Vinylene Carbonate Based Electrolytes for Si Anodes in Lithium Ion Batteries with NMR Spectroscopy
- 2018
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 1520-5126 .- 0002-7863. ; 140:31, s. 9854-9867
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Tidskriftsartikel (refereegranskat)abstract
- Fluoroethylene carbonate (FEC) and vinylene carbonate (VC) are widely used as electrolyte additives in lithium ion batteries. Here we analyze the solid electrolyte interphase (SEI) formed on binder-free silicon nanowire (SiNW) electrodes in pure FEC or VC electrolytes containing 1 M LiPF6by solid-state NMR with and without dynamic nuclear polarization (DNP) enhancement. We find that the polymeric SEIs formed in pure FEC or VC electrolytes consist mainly of cross-linked poly(ethylene oxide) (PEO) and aliphatic chain functionalities along with additional carbonate and carboxylate species. The formation of branched fragments is further confirmed by13C-13C correlation NMR experiments. The presence of cross-linked PEO-type polymers in FEC and VC correlates with good capacity retention and high Coulombic efficiencies of the SiNWs. Using29Si DNP NMR, we are able to probe the interfacial region between SEI and the Si surface for the first time with NMR spectroscopy. Organosiloxanes form upon cycling, confirming that some of the organic SEI is covalently bonded to the Si surface. We suggest that both the polymeric structure of the SEI and the nature of its adhesion to the redox-active materials are important for electrochemical performance.
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| 12. |
- KINYANJUI, FRANCIS GACHAO, 1981, et al.
(författare)
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Crystal structure and proton conductivity of BaSn0.6Sc0.4O3-delta: insights from neutron powder diffraction and solid-state NMR spectroscopy
- 2016
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 4:14, s. 5088-5101
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Tidskriftsartikel (refereegranskat)abstract
- The solid-state synthesis and structural characterisation of perovskite BaSn(1-x)ScxO(3-delta)(x = 0.0, 0.1, 0.2, 0.3, 0.4) and its corresponding hydrated ceramics are reported. Powder and neutron X-ray diffractions reveal the presence of cubic perovskites (space group Pm (3) over barm) with an increasing cell parameter as a function of scandium concentration along with some indication of phase segregation. Sn-119 and Sc-45 solid-state NMR spectroscopy data highlight the existence of oxygen vacancies in the dry materials, and their filling upon hydrothermal treatment with D2O. It also indicates that the Sn4+ and Sc3+ local distribution at the B-site of the perovskite is inhomogeneous and suggests that the oxygen vacancies are located in the scandium dopant coordination shell at low concentrations (x = 0.3). O-17 NMR spectra on O-17 enriched BaSn1-xScxO3-delta materials show the existence of Sn-O-Sn, Sn-O-Sc and Sc-O-Sc bridging oxygen environments. A further room temperature neutron powder diffraction study on deuterated BaSn0.6Sc0.4O3-delta refines the deuteron position at the 24k crystallographic site (x, y, 0) with x = 0.579(3) and y = 0.217(3) which leads to an O-D bond distance of 0.96(1) angstrom and suggests tilting of the proton towards the next nearest oxygen. Proton conduction was found to dominate in wet argon below 700 degrees C with total conductivity values in the range 1.8 x 10(-4) to 1.1 x 10(-3) S cm(-1) between 300 and 600 degrees C. Electron holes govern the conduction process in dry oxidizing conditions, whilst in wet oxygen they compete with protonic defects leading to a wide mixed conduction region in the 200 to 600 degrees C temperature region, and a suppression of the conductivity at higher temperature.
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| 13. |
- Liu, Tao, et al.
(författare)
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Understanding LiOH Formation in a Li-O2 Battery with LiI and H2O Additives
- 2019
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Ingår i: ACS Catalysis. - : American Chemical Society (ACS). - 2155-5435. ; 9:1, s. 66-77
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Tidskriftsartikel (refereegranskat)abstract
- LiI-promoted LiOH formation in Li-O2 batteries with wet ether electrolytes has been investigated by Raman, nuclear magnetic resonance spectroscopy, operando pressure tests, and molecular dynamics simulations. We find that LiOH formation is a synergistic effect involving both H2O and LiI additives, whereas with either alone Li2O2 forms. LiOH is generated via a nominal four-electron oxygen reduction reaction, the hydrogen coming from H2O and the oxygen from both O2 and H2O, and with fewer side reactions than typically associated with Li2O2 formation; the presence of fewer parasitic reactions is attributed to the proton donor role of water, which can coordinate to O2- and the higher chemical stability of LiOH. Iodide plays a catalytic role in decomposing H2O2/HO2- and thereby promoting LiOH formation, its efficacy being highly dependent on the water concentration. This iodide catalysis becomes retarded at high water contents due to the formation of large water-solvated clusters, and Li2O2 forms again.
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| 14. |
- Maxwell, Tania L., et al.
(författare)
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Global dataset of soil organic carbon in tidal marshes
- 2023
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Ingår i: Scientific Data. - : Springer Nature. - 2052-4463. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- Tidal marshes store large amounts of organic carbon in their soils. Field data quantifying soil organic carbon (SOC) stocks provide an important resource for researchers, natural resource managers, and policy-makers working towards the protection, restoration, and valuation of these ecosystems. We collated a global dataset of tidal marsh soil organic carbon (MarSOC) from 99 studies that includes location, soil depth, site name, dry bulk density, SOC, and/or soil organic matter (SOM). The MarSOC dataset includes 17,454 data points from 2,329 unique locations, and 29 countries. We generated a general transfer function for the conversion of SOM to SOC. Using this data we estimated a median (± median absolute deviation) value of 79.2 ± 38.1 Mg SOC ha−1 in the top 30 cm and 231 ± 134 Mg SOC ha−1 in the top 1 m of tidal marsh soils globally. This data can serve as a basis for future work, and may contribute to incorporation of tidal marsh ecosystems into climate change mitigation and adaptation strategies and policies.
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| 15. |
- Tapia-Ruiz, Nuria, et al.
(författare)
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2021 roadmap for sodium-ion batteries
- 2021
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Ingår i: Journal of Physics. - : Institute of Physics Publishing (IOPP). - 2515-7655. ; 3:3
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Tidskriftsartikel (refereegranskat)abstract
- Increasing concerns regarding the sustainability of lithium sources, due to their limited availability and consequent expected price increase, have raised awareness of the importance of developing alternative energy-storage candidates that can sustain the ever-growing energy demand. Furthermore, limitations on the availability of the transition metals used in the manufacturing of cathode materials, together with questionable mining practices, are driving development towards more sustainable elements. Given the uniformly high abundance and cost-effectiveness of sodium, as well as its very suitable redox potential (close to that of lithium), sodium-ion battery technology offers tremendous potential to be a counterpart to lithium-ion batteries (LIBs) in different application scenarios, such as stationary energy storage and low-cost vehicles. This potential is reflected by the major investments that are being made by industry in a wide variety of markets and in diverse material combinations. Despite the associated advantages of being a drop-in replacement for LIBs, there are remarkable differences in the physicochemical properties between sodium and lithium that give rise to different behaviours, for example, different coordination preferences in compounds, desolvation energies, or solubility of the solid-electrolyte interphase inorganic salt components. This demands a more detailed study of the underlying physical and chemical processes occurring in sodium-ion batteries and allows great scope for groundbreaking advances in the field, from lab-scale to scale-up. This roadmap provides an extensive review by experts in academia and industry of the current state of the art in 2021 and the different research directions and strategies currently underway to improve the performance of sodium-ion batteries. The aim is to provide an opinion with respect to the current challenges and opportunities, from the fundamental properties to the practical applications of this technology.
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| 16. |
- Temprano, Israel, et al.
(författare)
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Toward Reversible and Moisture-Tolerant Aprotic Lithium-Air Batteries
- 2020
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Ingår i: Joule. - : Elsevier BV. - 2542-4351. ; 4:11, s. 2501-2520
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Tidskriftsartikel (refereegranskat)abstract
- The development of moisture-tolerant, LiOH-based non-aqueous Li-O2 batteries is a promising route to bypass the inherent limitations caused by the instability of their typical discharge products, LiO2 and Li2O2. The use of the I−/I3− redox couple to mediate the LiOH-based oxygen reduction and oxidation reactions has proven challenging due to the multiple reaction paths induced by the oxidation of I− on cell charging. In this work, we introduce an ionic liquid to a glyme-based electrolyte containing LiI and water and demonstrate a reversible LiOH-based Li-O2 battery cycling that operates via a 4 e−/O2 process with a low charging overpotential (below 3.5 V versus Li/Li+). The addition of the ionic liquid increases the oxidizing power of I3−, shifting the charging mechanism from IO−/IO3− formation to O2 evolution.
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| 17. |
- Zhao, Evan Wenbo, et al.
(författare)
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In situ NMR metrology reveals reaction mechanisms in redox flow batteries
- 2020
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 579:7798, s. 224-228
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Tidskriftsartikel (refereegranskat)abstract
- Large-scale energy storage is becoming increasingly critical to balancing renewable energy production and consumption1. Organic redox flow batteries, made from inexpensive and sustainable redox-active materials, are promising storage technologies that are cheaper and less environmentally hazardous than vanadium-based batteries, but they have shorter lifetimes and lower energy density2,3. Thus, fundamental insight at the molecular level is required to improve performance4,5. Here we report two in situ nuclear magnetic resonance (NMR) methods of studying redox flow batteries, which are applied to two redox-active electrolytes: 2,6-dihydroxyanthraquinone (DHAQ) and 4,4′-((9,10-anthraquinone-2,6-diyl)dioxy) dibutyrate (DBEAQ). In the first method, we monitor the changes in the 1H NMR shift of the liquid electrolyte as it flows out of the electrochemical cell. In the second method, we observe the changes that occur simultaneously in the positive and negative electrodes in the full electrochemical cell. Using the bulk magnetization changes (observed via the 1H NMR shift of the water resonance) and the line broadening of the 1H shifts of the quinone resonances as a function of the state of charge, we measure the potential differences of the two single-electron couples, identify and quantify the rate of electron transfer between the reduced and oxidized species, and determine the extent of electron delocalization of the unpaired spins over the radical anions. These NMR techniques enable electrolyte decomposition and battery self-discharge to be explored in real time, and show that DHAQ is decomposed electrochemically via a reaction that can be minimized by limiting the voltage used on charging. We foresee applications of these NMR methods in understanding a wide range of redox processes in flow and other electrochemical systems.
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