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- Akinwekomi, Akeem, et al.
(author)
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Microstructural, Mechanical, and Electrochemical Characterization of CrMoNbTiZr High-Entropy Alloy for Biomedical Application
- 2023
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In: Materials. - : MDPI. - 1996-1944. ; 16:15
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Journal article (peer-reviewed)abstract
- High-entropy alloys (HEA) with superior biocompatibility, high pitting resistance, minimal debris accumulation, and reduced release of metallic ions into surrounding tissues are potential replacements for traditional metallic bio-implants. A novel equiatomic HEA based on biocompatible metals, CrMoNbTiZr, was consolidated by spark plasma sintering (SPS). The relative sintered density of the alloy was about 97% of the theoretical density, indicating the suitability of the SPS technique to produce relatively dense material. The microstructure of the sintered HEA consisted of a BCC matrix and Laves phase, corresponding to the prediction of the thermodynamic CALPHAD simulation. The HEA exhibited a global Vickers microhardness of 531.5 ± 99.7 HV, while the individual BCC and Laves phases had hardness values of 364.6 ± 99.4 and 641.8 ± 63.0 HV, respectively. Its ultimate compressive and compressive yield strengths were 1235.7 ± 42.8 MPa and 1110.8 ± 78.6 MPa, respectively. The elasticity modulus of 34.9 ± 2.9 GPa of the HEA alloy was well within the range of cortical bone and significantly lower than the values reported for commonly used biomaterials made from Ti-based and Cr–Co-based alloys. In addition, the alloy exhibited good resistance to bio-corrosion in PBS and Hanks solutions. The CrMoNbTiZr HEA exhibited an average COF of 0.43 ± 0.06, characterized mainly by abrasive and adhesive wear mechanisms. The CrMoNbTiZr alloy’s mechanical, bio-corrosion, and wear resistance properties developed in this study showed a good propensity for application as a biomaterial.
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| 2. |
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| 3. |
- Akinyemi, Felicia O., et al.
(author)
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Land transformation across agroecological zones reveals expanding cropland and settlement at the expense of tree-cover and wetland areas in Nigeria
- 2024
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In: Geo-spatial Information Science. - : Taylor & Francis. - 1009-5020 .- 1993-5153.
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Journal article (peer-reviewed)abstract
- Evaluating how land cover is being transformed is essential to identify patterns necessary to infer the change trajectories and the driving factors. This study considers the case of Nigeria, where various natural ecosystems are being converted and for which a current national scale assessment at high spatial resolution is lacking. Producing 30 m Landsat-based time-series data, we analyze change among land cover types (i.e. tree-covered area, grassland, wetland, waterbody, cropland, artificial surface, and otherland) across seven agroecological zones. The annual change intensity was assessed at multi-levels across two time-intervals (i.e. 2000–2013, 2013–2022). Distinguishing between natural land cover and human activity-related land-use, we estimate the extent of change signifying how humans have appropriated natural land cover. Insights from analysis at the interval level reveal that land transformation accelerated from 3.3% in 2000–2013 to 4.5% during 2013–2022 in all agroecological zones (e.g. rainforest, mangrove), except in Sudan savannah and Sahel savannah where speed was higher in 2000–2013 as grasslands were increasingly cultivated. Cropland expanded almost two-fold (22% to 37%), whereas tree-cover declined from 50% to 31% and wetland from 7% to 3.7% over the 23 years. Much loss of natural land cover (e.g. tree-cover, grassland, and wetland) to cropland occurred in 2000–2013 (22%) when most irrigation schemes in Nigeria were established. In contrast, the loss of natural land cover to settlement (0.9%) during 2000–2013 increased to 2.0% in 2013–2022. Of all agroecological zones, the mangrove zone was most disturbed as its persisting land cover areas reduced from 69% to 5% between 2000–2013 and 2013–2022. The amount of persisting land cover was highest in the Sudan savannah at 44% in 2000–2013 and 49% in 2013–2022. Processes of human-appropriated natural land cover in Nigeria are related to urbanization and cropland expansion into natural areas with some instances of natural regeneration, especially in croplands and abandoned settlement areas.
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| 4. |
- Israelsson, Jezzica, 1982-
(author)
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Making themselves heard : Women’s and men’s voice through the regional petitioning process in Sweden, 1758–1880
- 2024
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Doctoral thesis (other academic/artistic)abstract
- In the eighteenth and nineteenth centuries, thousands of women and men contacted the Governor’s Administration of Västmanland (Länsstyrelsen i Västmanlands län), handing in petitions concerning a wide range of matters. This thesis studies these cases to deepen our understanding of women's and men's ability and need to make themselves heard through the regional petitioning process. It also elucidates how this practice was intertwined with people's endeavours to make a living by focusing on the participation’s connection to resources. By studying petition registers and a corpus of nearly 3,000 surviving petition files, it contributes to existing scholarship in three important ways.First, the thesis introduces an extended theoretical conceptualisation of the regional petitioning process, where the relationship between petitioner and respondent is integral to the petitioning itself. This inclusion shows that the commonest reason why people needed to make themselves heard, thus establishing a relationship with the governor and his administration in the first place, was because of interactions and conflicts with other people over some resource, primarily credit, land or working roles. Everyday interactions led people to use the regional administration in legally regulated disputes, which ultimately had political implications. Second, by comparing the participation of women and men as well as that of labouring people to other groups, the thesis sheds light on how the ability and need to make yourself heard varied with gender, marital status and socioeconomic status. To participate in this manner was expensive, which undoubtedly affected poor people’s ability to do so. Nevertheless, we find people from the lowest rungs of society who vehemently protected their rights, sometimes as petitioners but more often as respondents. Women's participation at the administration, as in almost all official contexts at this time, was lower than men’s, sometimes only a fraction. Despite their low levels of participation, it nevertheless took many forms, a variety that continued into the nineteenth century.Third, the investigation studies how the ways people made themselves heard through the regional petitioning process evolved over time, making it one of few Swedish studies of petitioners and respondents beyond the beginning of the nineteenth century. Its temporal setting has yielded previously unknown insights into how the development of voice through the petitioning process was connected to administrative bureaucratisation, aspects of the judicial revolution, the gradual but non-linear disappearance of household culture and the emergence of a civil citizen.
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| 5. |
- Porosk, Ly, et al.
(author)
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Cell-Penetrating Peptides Predicted From CASC3, AKIP1, and AHRR Proteins
- 2021
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In: Frontiers in Pharmacology. - : Frontiers Media SA. - 1663-9812. ; 12
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Journal article (peer-reviewed)abstract
- Peptides can be used as research tools and for diagnostic or therapeutic applications. Peptides, alongside small molecules and antibodies, are used and are gaining further interest as protein-protein interaction (PPI) modulators. Peptides have high target specificity and high affinity, but, unlike small molecule modulators, they are not able to cross the cell membranes to reach their intracellular targets. To overcome this limitation, the special property of the cell-penetrating peptides (CPPs) could benefit their cause. CPPs are a class of peptides that can enter the cells and with them also deliver the attached cargoes. Today, with the advancement of in silico prediction tools and the availability of protein databases, designing new and multifunctional peptides that are able to reach intracellular targets and inhibit certain cellular processes in a very specific manner is reachable. Although there are several efficient CPP sequences already known, the discovery of new CPPs is crucial for the development of efficient delivery methods for both biotechnological and therapeutic applications. In this work, we chose 10 human nuclear proteins from which we predicted new potential CPP sequences by using three different CPP predictors: cell-penetrating peptide prediction tool, CellPPD, and SkipCPP-Pred. From each protein, one predicted CPP sequence was synthesized and its internalization into cells was assessed. Out of the tested sequences, three peptides displayed features characteristic to CPPs. These peptides and also the predicted peptide sequences could be used to design and modify new CPPs. In this work, we show that we can use protein sequences as input for generating new peptides with cell internalization properties. Three new CPPs, AHRR(8-24), CASC3(251-264), and AKIP1(27-37), can be further used for the delivery of other cargoes or designed into multifunctional peptides with capability of internalizing cells.
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| 7. |
- Akishev, Gabdolla, et al.
(author)
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Inequalities for the Fourier coefficients in unbounded orthogonal systems in generalized Lorentz spaces
- 2020
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In: Nonlinear Studies. - : Cambridge Scientific Publishers Ltd. - 1359-8678. ; 27:4, s. 1137-1155
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Journal article (peer-reviewed)abstract
- This paper is an essential complement of the research recently presented in [1], [2]. A number of classical Fourier inequalities related to Fourier coefficients with respect to unbounded orthogonal systems are generalized and complemented. All results are given in the case of generalized Lorentz spaces.
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| 8. |
- Akishev, Gabdolla, et al.
(author)
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Some New Fourier and Jackson-Nikol'skii Type Inequalities In Unbounded Orthonormal Systems
- 2021
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In: Constructive Mathematical Analysis. - : Tuncer ACAR. - 2651-2939. ; :3, s. 291-304
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Journal article (peer-reviewed)abstract
- We consider the generalized Lorentz space L ;q dened via a continuous and concave function and the Fourier series of a function with respect to an unbounded orthonormal system. Some new Fourier and Jackson-Nikol'skii type inequalities in this frame are stated, proved and discussed. In particular, the derived results generalize and unify several well-known results but also some new applications are pointed out.
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