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- Sousa, O. M., et al.
(författare)
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Charging behavior of ZnMn2O4 and LiMn2O4 in a zinc- and lithium-ion battery : an ab initio study
- 2024
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Ingår i: Journal of Physics. - : Institute of Physics Publishing (IOPP). - 2515-7655. ; 6:2
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Tidskriftsartikel (refereegranskat)abstract
- In the field of sustainable energy storage systems, zinc-ion batteries (ZIB) employing aqueous electrolytes have emerged as viable successors to the widely used lithium-ion batteries, attributed to their cost-effectiveness, environmental friendliness, and intrinsic safety features. Despite these advantages, the performance of ZIBs is significantly hindered by the scarcity of suitable cathode materials, positioning manganese zinc oxide (ZnMn2O4) as a potential solution. In this study, we describe the ZnMn2O4 (ZMO) compound focusing on its properties variations during Zn extraction and potential battery applications. For the sake of comparison, we also analyze the same properties of the LiMn2O4 in its tetragonal phase (TLMO), for the first time, motivated by a recent discovery that the substitution of Zn ions by Li in ZMO forms isostructural TLMO compound at room temperature. The study was conducted within the density functional theory (DFT) framework, where the structural, electronic, magnetic, electrochemical, and spectroscopic properties of ZMO and TLMO are investigated under various conditions. Although both systems crystallize in tetragonal structures, they demonstrate distinct electronic and magnetic properties due to different oxidation states of the Mn. Computationally optimized lattice parameters align closely with experimental values. The TLMO exhibits a narrower band gap compared to ZMO, indicating enhanced electrical conductivity. In addition, TLMO presented a lower diffusion energy barrier than ZMO, indicating better ionic conductivity. To evaluate the potential application of these materials in battery technologies, we further explored their volume changes during charging/discharging cycles, simulating Zn or Li ions extraction. TLMO underwent a significant volume contraction of 5.8% upon complete Li removal, while ZMO experienced a more pronounced contraction of 12.5% with full Zn removal. By adjusting ion extraction levels, it is possible to reduce these contractions, thereby approaching more viable battery applications. Voltage profiles, constructed from DFT-based simulation results, unveiled an average voltage of 4.05 V for TLMO, closely matching experimental values. Furthermore, spectroscopy results provide insights into the electronic transitions and validate the computational findings, consolidating our understanding of the intrinsic properties of ZMO and TLMO.
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| 2. |
- Sousa, O. M., et al.
(författare)
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Pressure effect on the structural, electronic, and magnetic properties of the battery cathode material LiMn2O4 : An ab-initio study
- 2023
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Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier. - 0022-3697 .- 1879-2553. ; 175
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Tidskriftsartikel (refereegranskat)abstract
- LiMn2O4 is a battery cathode material with desirable properties such as low cost, low toxicity, high natural abundance of Mn, and environmental compatibility. By means of first-principles calculations, we study the structural, magnetic, and electronic properties of LiMn2O4 under ambient conditions and high hydrostatic pressures (until 20 GPa). We obtain two oxidation states for Mn, even using a cubic structure, which differ in all analyzed properties: structural, electronic, and magnetic. At P > 0, such properties were found to display a standard behavior decreasing smoothly and linearly with pressure. Furthermore, the enthalpy of cubic and orthorhombic structures under low and high-pressure conditions were examined, showing that no cubic to orthorhombic phase transition exists in all the investigated pressure range, nor is a magnetic cubic to a non-magnetic cubic phase transition possible.
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| 4. |
- Awadalla, M. K. A., et al.
(författare)
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Improved Homology Model of the Human all-trans Retinoic Acid Metabolizing Enzyme CYP26A1
- 2016
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Ingår i: Molecules. - : MDPI AG. - 1420-3049 .- 1431-5157. ; 21:3
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Tidskriftsartikel (refereegranskat)abstract
- A new CYP26A1 homology model was built based on the crystal structure of cyanobacterial CYP120A1. The model quality was examined for stereochemical accuracy, folding reliability, and absolute quality using a variety of different bioinformatics tools. Furthermore, the docking capabilities of the model were assessed by docking of the natural substrate all-trans-retinoic acid (atRA), and a group of known azole- and tetralone-based CYP26A1 inhibitors. The preferred binding pose of atRA suggests the (4S)-OH-atRA metabolite production, in agreement with recently available experimental data. The distances between the ligands and the heme group iron of the enzyme are in agreement with corresponding distances obtained for substrates and azole inhibitors for other cytochrome systems. The calculated theoretical binding energies agree with recently reported experimental data and show that the model is capable of discriminating between natural substrate, strong inhibitors (R116010 and R115866), and weak inhibitors (liarozole, fluconazole, tetralone derivatives).
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| 7. |
- Eriksson, Mimmi, et al.
(författare)
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Effects of Gas Layer Thickness on Capillary Interactions at Superhydrophobic Surfaces
- 2024
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 40:9, s. 4801-4810
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Tidskriftsartikel (refereegranskat)abstract
- Strongly attractive forces act between superhydrophobic surfaces across water due to the formation of a bridging gas capillary. Upon separation, the attraction can range up to tens of micrometers as the gas capillary grows, while gas molecules accumulate in the capillary. We argue that most of these molecules come from the pre-existing gaseous layer found at and within the superhydrophobic coating. In this study, we investigate how the capillary size and the resulting capillary forces are affected by the thickness of the gaseous layer. To this end, we prepared superhydrophobic coatings with different thicknesses by utilizing different numbers of coating cycles of a liquid flame spraying technique. Laser scanning confocal microscopy confirmed an increase in gas layer thickness with an increasing number of coating cycles. Force measurements between such coatings and a hydrophobic colloidal probe revealed attractive forces caused by bridging gas capillaries, and both the capillary size and the range of attraction increased with increasing thickness of the pre-existing gas layer. Hence, our data suggest that the amount of available gas at and in the superhydrophobic coating determines the force range and capillary growth.
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| 8. |
- Eriksson, Mimmi, et al.
(författare)
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Effects of liquid surface tension on gas capillaries and capillary forces at superamphiphobic surfaces
- 2023
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Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- The formation of a bridging gas capillary between superhydrophobic surfaces in water gives rise to strongly attractive interactions ranging up to several micrometers on separation. However, most liquids used in materials research are oil-based or contain surfactants. Superamphiphobic surfaces repel both water and low-surface-tension liquids. To control the interactions between a superamphiphobic surface and a particle, it needs to be resolved whether and how gas capillaries form in non-polar and low-surface-tension liquids. Such insight will aid advanced functional materials development. Here, we combine laser scanning confocal imaging and colloidal probe atomic force microscopy to elucidate the interaction between a superamphiphobic surface and a hydrophobic microparticle in three liquids with different surface tensions: water (73 mN m−1), ethylene glycol (48 mN m−1) and hexadecane (27 mN m−1). We show that bridging gas capillaries are formed in all three liquids. Force-distance curves between the superamphiphobic surface and the particle reveal strong attractive interactions, where the range and magnitude decrease with liquid surface tension. Comparison of free energy calculations based on the capillary menisci shapes and the force measurements suggest that under our dynamic measurements the gas pressure in the capillary is slightly below ambient.
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| 9. |
- Haque, M. Atiqul, et al.
(författare)
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Bangladeshi school-age children's experiences and perceptions on child maltreatment : A qualitative interview study
- 2017
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Ingår i: Child Care Health and Development. - : John Wiley & Sons. - 0305-1862 .- 1365-2214. ; 43:6, s. 876-883
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundChild maltreatment (CM) is a public health problem and is recognized as a huge barrier for child development. Most of the research and definitions on CM are from the perspective of high-income western countries. Because no major studies have been conducted on CM in Bangladesh, the aim of the current study was to explore the experiences of and perceptions on CM in school-age children in rural and urban Bangladesh in order to understand maltreatment in a local context and from a child perspective. MethodsSemistructured individual interviews with 24 children (13 boys and 11 girls), between the ages of 9 and 13years of which 11 were schoolgoing and 13 non-schoolgoing, were conducted during July 2013 and analysed according to qualitative content analysis. ResultsCM was a common and painful experience with serious physical and emotional consequences but highly accepted by the society. Vulnerable groups were especially young children, girls, and poor children. The children's voices were not heard due to their low status and low position in their families, schools, and working places. The main theme that emerged in the analysis was children's subordination, which permeated the five categories: (a) perception of children's situation in society, (b) understanding children's development and needs, (c) CM associated to school achievement, (d) negative impact of CM, and (e) emotional responses. ConclusionsDifferent kinds of abuse are obviously common in Bangladesh, and the schools do not follow the law from 2011 prohibiting corporal punishment at school. The society has to take further steps to live up to the UN Convention on the Rights of the Child, which was ratified already in 1990, to protect the Bangladeshi children from CM.
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| 10. |
- Haque, M. Atiqul, 1970-, et al.
(författare)
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Child Maltreatment Portrayed in Bangladeshi Newspapers
- 2020
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Ingår i: Child Abuse Review. - : WILEY. - 0952-9136 .- 1099-0852. ; 29:5, s. 448-462
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Tidskriftsartikel (refereegranskat)abstract
- As in most low-income countries, there is a lack of scientific information on the incidence and pattern of child maltreatment (CM) in Bangladesh. However, the role of the media to disclose CM and to develop public awareness in society is noteworthy. The present study assessed newspaper reports about CM by type and socio-demographics of victims and perpetrators in Bangladesh. In total, 790 news articles were collected retrospectively from four Bengali- and two English-language newspapers from October to December 2014. Among all reported incidents, almost half of the CM cases concerned alleged physical abuse (26%) and sexual abuse (22%). Neglect and emotional or psychological abuse received less coverage. Female children were to a high degree (90%) victims of sexual abuse. The main perpetrators were males, and they were often known to the victims. Approximately 32 per cent of the reported abuse cases resulted in death and were related to rape, family violence, administrative negligence, abduction and ransom demand. Some of these deaths were suicides. News stories concerning CM were often reported in an unethical way by identifying the victim and not respecting child rights. Further, the stories seldom discussed the individual or social consequences of CM, or how maltreatment could be prevented. 'The present study assessed newspaper reports about CM by type and socio-demographics of victims and perpetrators in Bangladesh' Key Practitioner Messages The main types of reported cases of CM in Bangladeshi print media are physical abuse and sexual abuse, and there is a high proportion of fatal consequences. The perpetrators are often known to the victims. The identity of the victim is frequently reported, potentially putting the child at risk and violating child rights. Bangladeshi print media seldom discusses individual or societal consequences of CM, or how it could be prevented.
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