| 1. |
- Ademuyiwa, Adesoji O., et al.
(författare)
-
Determinants of morbidity and mortality following emergency abdominal surgery in children in low-income and middle-income countries
- 2016
-
Ingår i: BMJ Global Health. - : BMJ Publishing Group Ltd. - 2059-7908. ; 1:4
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Child health is a key priority on the global health agenda, yet the provision of essential and emergency surgery in children is patchy in resource-poor regions. This study was aimed to determine the mortality risk for emergency abdominal paediatric surgery in low-income countries globally.Methods: Multicentre, international, prospective, cohort study. Self-selected surgical units performing emergency abdominal surgery submitted prespecified data for consecutive children aged <16 years during a 2-week period between July and December 2014. The United Nation's Human Development Index (HDI) was used to stratify countries. The main outcome measure was 30-day postoperative mortality, analysed by multilevel logistic regression.Results: This study included 1409 patients from 253 centres in 43 countries; 282 children were under 2 years of age. Among them, 265 (18.8%) were from low-HDI, 450 (31.9%) from middle-HDI and 694 (49.3%) from high-HDI countries. The most common operations performed were appendectomy, small bowel resection, pyloromyotomy and correction of intussusception. After adjustment for patient and hospital risk factors, child mortality at 30 days was significantly higher in low-HDI (adjusted OR 7.14 (95% CI 2.52 to 20.23), p<0.001) and middle-HDI (4.42 (1.44 to 13.56), p=0.009) countries compared with high-HDI countries, translating to 40 excess deaths per 1000 procedures performed.Conclusions: Adjusted mortality in children following emergency abdominal surgery may be as high as 7 times greater in low-HDI and middle-HDI countries compared with high-HDI countries. Effective provision of emergency essential surgery should be a key priority for global child health agendas.
|
|
| 2. |
- Thomas, HS, et al.
(författare)
-
- 2019
-
swepub:Mat__t
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
- El Ghazaly, Ahmed
(författare)
-
Acoustic Platform for MXene Synthesis and Electrochemical Behaviour of i-MXenes in Aqueous Electrolytes
- 2021
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Climate Change is believed to be the greatest global challenge and on its forefront is the topic of energy. While being of extreme importance, debates over energy have become a normality. The related field of material synthesis for energy storage applications has also been growing, as well as the demand for industrial electrification from renewable sources of energy. Water-based supercapacitors are a type of energy storage devices that can deliver high power densities while maintaining long term cyclability in an environmen-tally friendly media. However, their challenges include maintaining high per-formance in term of energy density, safety, and low cost of electrode manu-facturing. MXene is family of two-dimensional transition metal carbides/nitrides that are terminated with H, OH and F groups. The material demonstrates superior physical and chemical properties related to energy applications in compari-son to its 3D parent material, the MAX phase. Since its discovery in 2011, MXene, such as Ti3C2Tz, has been widely investigated in the field of energy storage due to its high conductivity (20,000 S.cm-1) and a volumetric capac-itance that can reach 900 Fcm-3. However, reported synthesis processes for MXene are fraught with hazardous procedures that are time consuming. The first section of this thesis presents a new innovative method for Ti3C2Tz MXene synthesis, in which MXene was synthesized in a few milliseconds with the assistance of 30 MHz frequency surface acoustic waves (SAW) and 0.05M of LiF. The aluminium element in the Ti3AlC2 MAX phase was etched by so called “localized HF”, and the powder was converted to 2D Ti3C2Tz. This method showed resulting MXene comparable to that of previ-ously reported synthesis techniques, as demonstrated by the material’s elec-trochemical performance. The second section of the thesis focuses on investigating the electrochemical performance of a comparatively new family of MXene, coined i-MXene, in aqueous electrolyte. i-MXene, reported in 2017, has the chemical formula Mo1.33CTz and is a product of chemical etching of the in-plane chemically ordered (Mo2/3Sc1/3)2AlC i-MAX phase. The Mo1.33CTz was studied in a sul-phuric acid electrolyte. This electrolyte sets a limit for the electrode potential window and capacitance, and therefore, post-synthesis treatment protocols was used to enhance the electrochemical performance. The Mo1.33CTz recorded a volumetric capacitance of 1050 Fcm-3 and1600 Fcm-3 for hydrogel treatment and heat-treated electrodes, respectively. Moreover, mixing Mo1.33CTz with MoS2 and graphene improved both the specific capacitance and the electrode stability even further. The electrochemical properties of Mo1.33CTz were thereafter explored in dif-ferent sulfate-based aqueous electrolytes with univalent (Li+, Na+, and K+) and divalent (Mg2+ Mn2+ or Zn2+) cations. Mo1.33CTz exhibited a wider po-tential window without degradation, expanding the previously reported limit in sulphuric acid for both symmetric and asymmetric devices. Lithium chlo-ride gave the best results, being an electrolyte based on a natural salt that has high solubility at room temperature. It presented a large potential window, -1.2 to +0.3V (vs. Ag/AgCl), and a volumetric capacitance of ~800 Fcm−3 at a scan rate of 2 mVs−1. In addition, the performance of a Mo1.33CTz //MnxOn asymmetric device was tested in 5M LiCl electrolyte. The results showed a potential window of 2 V, a volumetric energy density of 58 mWhcm-3, and a 100% columbic efficiency after 10,000 charge/discharge cycles. A cyclic sta-bility is crucial for practical applications, and altogether, the promising re-sults motivate further exploration of i-MXenes for energy storage and be-yond.
|
|
| 6. |
- Etman, Ahmed S., et al.
(författare)
-
Flexible Freestanding MoO3-x-Carbon Nanotubes-Nanocellulose Paper Electrodes for Charge-Storage Applications
- 2019
-
Ingår i: ChemSusChem. - : John Wiley & Sons. - 1864-5631 .- 1864-564X. ; 12:23, s. 5157-5163
-
Tidskriftsartikel (refereegranskat)abstract
- Herein, a one‐step synthesis protocol was developed for synthesizing freestanding/flexible paper electrodes composed of nanostructured molybdenum oxide (MoO3−x) embedded in a carbon nanotube (CNT) and Cladophora cellulose (CC) matrix. The preparation method involved sonication of the precursors, nanostructured MoO3−x, CNTs, and CC with weight ratios of 7:2:1, in a water/ethanol mixture, followed by vacuum filtration. The electrodes were straightforward to handle and possessed a thickness of approximately 12 μm and a mass loading of MoO3−x–CNTs of approximately 0.9 mg cm−2. The elemental mapping showed that the nanostructured MoO3−x was uniformly embedded inside the CNTs–CC matrix. The MoO3−x–CNTs–CC paper electrodes featured a capacity of 30 C g−1, normalized to the mass of MoO3−x–CNTs, at a current density of 78 A g−1 (corresponding to a rate of approximately 210 C based on the MoO3 content, assuming a theoretical capacity of 1339 C g−1), and exhibited a capacity retention of 91 % over 30 000 cycles. This study paves the way for the manufacturing of flexible/freestanding nanostructured MoO3−x‐based electrodes for use in charge‐storage devices at high charge/discharge rates.
|
|
| 7. |
- Zheng, Wei, et al.
(författare)
-
Boosting the volumetric capacitance of MoO3-x free-standing films with Ti3C2 MXene
- 2021
-
Ingår i: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 370
-
Tidskriftsartikel (refereegranskat)abstract
- The high theoretical capacitance of molybdenum trioxide (MoO3) renders it an attractive supercapacitor electrode material. However, its low electronic conductivity restricts charge transfer and slows its reaction kinetics. Herein, we vacuum filtered porous, free-standing, flexible and highly conductive films comprised of oxygen vacancy-rich MoO3-x nanobelts and delaminated Ti3C2 MXene in a mass ratio of 80:20, respectively. When tested as supercapacitor electrodes, in a 5 M LiCl electrolyte, volumetric capacitances of 631 F cm−3 at 1 A g−1, and 474 F cm−3 at 10 A g−1 were obtained. To increase the energy density, asymmetric supercapacitors, wherein the anodes were MoO3-based and the cathodes were nitrogen-doped activated carbon were assembled and tested. The resulting volumetric energy density was 48.6 Wh L−1. After 20,000 continuous charge/discharge cycles at 20 A g−1, 96.3 % of the initial charge remained. These values are outstanding for free-standing supercapacitor electrodes, especially in aqueous electrolytes.
|
|
| 8. |
- Zheng, Wei, et al.
(författare)
-
Flexible Free-Standing MoO3/Ti3C2Tz MXene Composite Films with High Gravimetric and Volumetric Capacities
- 2021
-
Ingår i: Advanced Science. - : Wiley. - 2198-3844. ; 8:3
-
Tidskriftsartikel (refereegranskat)abstract
- Enhancing both the energy storage and power capabilities of electrochemical capacitors remains a challenge. Herein, Ti3C2Tz MXene is mixed with MoO3 nanobelts in various mass ratios and the mixture is used to vacuum filter binder free, open, flexible, and free-standing films. The conductive Ti3C2Tz flakes bridge the nanobelts, facilitating electron transfer; the randomly oriented, and interconnected, MoO3 nanobelts, in turn, prevent the restacking of the Ti3C2Tz nanosheets. Benefitting from these advantages, a MoO3/Ti3C2Tz film with a 8:2 mass ratio exhibits high gravimetric/volumetric capacities with good cyclability, namely, 837 C g−1 and 1836 C cm−3 at 1 A g−1 for an ≈ 10 µm thick film; and 767 C g−1 and 1664 C cm−3 at 1 A g−1 for ≈ 50 µm thick film. To further increase the energy density, hybrid capacitors are fabricated with MoO3/Ti3C2Tz films as the negative electrodes and nitrogen-doped activated carbon as the positive electrodes. This device delivers maximum gravimetric/volumetric energy densities of 31.2 Wh kg−1 and 39.2 Wh L−1, respectively. The cycling stability of 94.2% retention ratio after 10 000 continuous charge/discharge cycles is also noteworthy. The high energy density achieved in this work can pave the way for practical applications of MXene-containing materials in energy storage devices.
|
|
| 9. |
- Bischak, Connor G., et al.
(författare)
-
Liquid-like Interfaces Mediate Structural Phase Transitions in Lead Halide Perovskites
- 2020
-
Ingår i: Matter. - : Elsevier BV. - 2590-2393 .- 2590-2385. ; 3:2, s. 534-545
-
Tidskriftsartikel (refereegranskat)abstract
- Microscopic pathways of structural phase transitions inmetal halide perovskites are difficult to probe because they occur over disparate time and length scales and because electron-based microscopies typically used to directly probe nanoscale dynamics of phase transitions often damage metal halide perovskite materials. Using in situ nanoscale cathodoluminescence microscopy with low electron beam exposure, we visualize nucleation and growth in the thermally driven transition to the perovskite phase in hundreds of non-perovskite phase nanowires. In combination with molecular dynamics simulations, we reveal that the transformation does not follow a simple martensitic mechanism, but proceeds despite a substantial energy barrier via ion diffusion through a liquid-like interface between the two structures. While cations are disordered in this liquid-like region, the halide ions retain substantial spatial correlations. This detailed picture not only reveals how phase transitions between disparate structures can proceed, but also opens the possibility to control such processes.
|
|
| 10. |
- Colbin, Lars Olow Simon, et al.
(författare)
-
Anodic dissolution of aluminum in non-aqueous electrolyte solutions for sodium-ion batteries
- 2023
-
Ingår i: Energy Advances. - : Royal Society of Chemistry. - 2753-1457. ; 3:1, s. 143-
-
Tidskriftsartikel (refereegranskat)abstract
- Anodic dissolution of aluminum (commonly called aluminum corrosion) is a potential issue in sodium-ion batteries. Herein, it is demonstrated how different sodium-ion battery electrolyte solutions affect this phenomenon. The type of electrolyte was critical for the presence of anodic dissolution, while the solvent appeared to alter the dissolution process.
|
|
