| 1. |
- Almessiere, M. A., et al.
(författare)
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Review on functional bi-component nanocomposites based on hard/soft ferrites : Structural, magnetic, electrical and microwave absorption properties
- 2021
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Ingår i: Nano-Structures and Nano-Objects. - : Elsevier B.V.. - 2352-507X. ; 26
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Tidskriftsartikel (refereegranskat)abstract
- Bi-component hard (H) (hexaferrite) and soft (S) (spinel) ferrites nanocomposites are gaining interest scientifically and technically, not only for combining the high magnetization of spinel ferrite nanomaterials and the high coercivity of hexaferrite magnetic nanomaterials but also for the outstanding exchange-coupling behavior among hard and soft magnetic phase. The improved magnetic features lead to produce a new nanocomposite with higher microwave absorption capacity in comparison with ferrites with a single absorption mechanism. Exchange-coupled effect has a potential application based on microwave absorption, recording media, permanent magnets, biomedical and other applications. Intensive studies have been conducted on this topic to produce hard/soft (H/S) ferrite nanocomposites with establishment of exchange coupled effect between the two phases. Preparation methods, microstructure, magnetics features, microwave and dielectric properties, and applications are elaborated. Consequently, a comprehensive effort has been made to contain an original reference investigating in detail the precise outcomes of the published papers.
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| 2. |
- Almessiere, M. A., et al.
(författare)
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Effects of Ce-Dy rare earths co-doping on various features of Ni-Co spinel ferrite microspheres prepared via hydrothermal approach
- 2021
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Ingår i: Journal of Materials Research and Technology. - : Elsevier BV. - 2238-7854 .- 2214-0697. ; 14, s. 2534-2553
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Tidskriftsartikel (refereegranskat)abstract
- The effects of Ce-Dy co-doping on the crystal structure, optical, dielectric, magnetic properties, and hyperfine interactions of Ni-Co spinel ferrite microspheres synthesized hydrothermally have been studied. A series of ferrites with the general formula Ni0.5-Co0.5CexDyxFe2-2xO4 were synthesized with x values ranging from 0.00 to 0.10. The phase, crystallinity, and morphology of ferrite microspheres were analyzed by X-ray powder diffractometry (XRD), scanning and transmission electron microscopes (SEM and TEM), respectively. The structural analyses of the synthesized ferrite microspheres confirmed their high purity and cubic crystalline phase. The Diffuse reflectance spectroscopic (DRS) measurements were presented to calculate direct optical energy band gaps (E-g) and is found in the range 1.63 eV - 1.84 eV. Fe-57 Mossbauer spectroscopy showed that the hyperfine magnetic field of tetrahedral (A) and octahedral (B) sites decreased with the substitution of Dy3+-Ce3+ ions that preferrentially occupy the B site. The impact of the rare-earth content (x) on the magnetic features of the prepared NiCo ferrite microspheres was investigated by analyzing M-H loops, which showed soft ferrimagnetism. The magnetic features illustrate a great impact of the incorporation of Ce3+-Dy3+ ions within the NiCo ferrite structure. The saturation magnetization (M-s), remanence (M-r), and coercivity (H-c) increased gradually with increasing Ce-Dy content. At x = 0.04, M-s, M-r, and H-c attain maximum values of about 31.2 emu/g, 11.5 emu/g, and 512.4 Oe, respectively. The Bohr magneton (n(B)) and magneto-crystalline anisotropy constant (K-eff) were also determined and evaluated with correlation to other magnetic parameters. Further increase in Ce3+-Dy3+ content (i.e., x >= 0.06) was found to decrease M-s, M-r, and H-c values. The variations in magnetic parameters (M-s, M-r, and H-c) were largely caused by the surface spins effect, the variations in crystallite/particle size, the distribution of magnetic ions into the different sublattices, the evolutions of magneto-crystalline anisotropy, and the variations in the magnetic moment (n(B)). The squareness ratios were found to be lower than the predicted theoretical value of 0.5 for various samples, indicating that the prepared Ce-Dy substituted NiCo ferrite microspheres are composed of NPs with single-magnetic domain (SMD). Temperature and frequency-dependent electrical and dielectric measurements have been done to estimate the ac/dc conductivity, dielectric constant, and tangent loss values for all the samples. The ac conductivity measurements confirmed the power-law rules, largely dependent on Ce-Dy content. Impedance analysis stated that the conduction mechanisms in all samples are mainly due to the grains-grain boundaries. The dielectric constant of NiCo ferrite microspheres give rise to normal dielectric distribution, with the frequency depending strongly on the Ce-Dy content. The observed variation in tangential loss with frequency can be attributed to the conduction mechanism in ferrites, like Koop's phenomenological model.
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| 3. |
- Slimani, Y., et al.
(författare)
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Ultrasound-assisted synthesis and magnetic investigations of Ni0.4Cu0.4Zn0.2GaxGdxFe2-2xO4 (0.00 <= x <= 0.04) nanosized spinel ferrites
- 2022
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Ingår i: Applied Physics A. - : Springer Nature. - 0947-8396 .- 1432-0630. ; 128:7
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Tidskriftsartikel (refereegranskat)abstract
- This study focused on the impact of Ga-Gd co-substitution on the structural, magnetic features and hyperfine interactions of nanosized NiCuZn spinel ferrites [Ni0.4Cu0.4Zn0.2GaxGdxFe2-2xO4 (0.00 <= x <= 0.04) NSFs] synthesized via sonochemical approach using ultrasonic irradiation. X-ray powder pattern (XRD) analyses confirmed cubic spinel structures of products. Crystallites and particle sizes of all samples are found to be between 9-14 nm and 18-22 nm, respectively. The NSF morphology and chemical composition were investigated by transmission and scanning electron microscope (TEM and SEM) along with energy-dispersive X-ray (EDX). The cation distribution of all ions was evaluated by Mossbauer spectroscopy. The high spin Fe3+ ions determined the isomer shift (I.S.) values. For lower rare-earth dopant ratios, we found that Gd3+ ions occupy B sites, while Ga3+ ions reside in A sites, and thereafter, some Ga3+ ions start to enter B sites. Magnetometry measurements were used to evaluate the effect of magnetic field (H) and temperature (T) on the magnetization of products. For each sample, both coercivity (H-c) and saturation magnetization (M-s) increase when the T decreases below ambient temperature. All substituted samples display M-s values higher than those of non-substituted ones; however, H-c values diminish for x content up to 0.02 and thereafter enlarge. Different magnetization measurements revealed superparamagnetic-to-ferromagnetic transition below the blocking temperature (T-B).
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| 4. |
- Buruk, Oguz'Oz', et al.
(författare)
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Children in 2077: Designing children's technologies in the age of transhumanism
- 2020
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Ingår i: Conference on Human Factors in Computing Systems - Proceedings. - New York, NY, USA : ACM.
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Konferensbidrag (refereegranskat)abstract
- What for and how will we design children's technologies in the transhumanism age, and what stance will we take as designers? This paper aims to answer this question with 13 fictional abstracts from sixteen authors of different countries, institutions and disciplines. Transhumanist thinking envisions enhancing human body and mind by blending human biology with technological augmentations. Fundamentally, it seeks to improve the human species, yet the impacts of such movement are unknown and the implications on children's lives and technologies were not explored deeply. In an age, where technologies such as under-skin chips or brain-machine interfaces can clearly be defined as transhumanist, our aim is to reveal probable pitfalls and benefits of those technologies on children's lives by using the power of design fiction. Thus, main contribution of this paper is to create diverse presentation of provocative research ideas that will foster the discussion on the transhumanist technologies impacting the lives of children in the future.
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| 5. |
- Kaya, Ibrahim, et al.
(författare)
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Brain region-specific amyloid plaque-associated myelin lipid loss, APOE deposition and disruption of the myelin sheath in familial Alzheimer's disease mice
- 2020
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Ingår i: Journal of Neurochemistry. - : Wiley. - 0022-3042 .- 1471-4159. ; 154:1, s. 84-98
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Tidskriftsartikel (refereegranskat)abstract
- There is emerging evidence that amyloid beta (A beta) aggregates forming neuritic plaques lead to impairment of the lipid-rich myelin sheath and glia. In this study, we examined focal myelin lipid alterations and the disruption of the myelin sheath associated with amyloid plaques in a widely used familial Alzheimer's disease (AD) mouse model; 5xFAD. This AD mouse model has A beta(42) peptide-rich plaque deposition in the brain parenchyma. Matrix-assisted laser desorption/ionization imaging mass spectrometry of coronal brain tissue sections revealed focal A beta plaque-associated depletion of multiple myelin-associated lipid species including sulfatides, galactosylceramides, and specific plasmalogen phopshatidylethanolamines in the hippocampus, cortex, and on the edges of corpus callosum. Certain phosphatidylcholines abundant in myelin were also depleted in amyloid plaques on the edges of corpus callosum. Further, lysophosphatidylethanolamines and lysophosphatidylcholines, implicated in neuroinflammation, were found to accumulate in amyloid plaques. Double staining of the consecutive sections with fluoromyelin and amyloid-specific antibody revealed amyloid plaque-associated myelin sheath disruption on the edges of the corpus callosum which is specifically correlated with plaque-associated myelin lipid loss only in this region. Further, apolipoprotein E, which is implicated in depletion of sulfatides in AD brain, is deposited in all the A beta plaques which suggest apolipoprotein E might mediate sulfatide depletion as a consequence of an immune response to A beta deposition. This high-spatial resolution matrix-assisted laser desorption/ionization imaging mass spectrometry study in combination with (immuno) fluorescence staining of 5xFAD mouse brain provides new understanding of morphological, molecular and immune signatures of A beta plaque pathology-associated myelin lipid loss and myelin degeneration in a brain region-specific manner.
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| 6. |
- Obaid, Mohammad, 1982, et al.
(författare)
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Collective co-design activities with children for designing classroom robots
- 2023
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Ingår i: ACM International Conference Proceeding Series. ; , s. 229-237
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Konferensbidrag (refereegranskat)abstract
- In order to design classroom robots that meet children's expectations, it may be useful to involve children in the design process. In this paper, we propose a suite of activities that can be utilized collectively to help in co-designing classroom robots. We outline the details of a combination of activities including building a robot model using a dedicated robot toolkit, a placement activity, a story-telling activity, and an interview. We explore the use of these activities through a study with 31 children (8-15 years old), where we analyzed the data using a framework for the design of social robots extended to cover the classroom situation. Our study showed that the activities could help distinguish some clear group preferences regarding the embodiment of the robot, especially the head, arms, and legs, the role of the robot, and the personality. While we used these activities in a study to illustrate their use for an open-ended design process of a classroom robot, we argue that the proposed suite of activities complement each other and may help robot designers to involve children in the design process in a holistic way. This can allow designers to gain elaborate and in-depth insight from children who do not usually (and necessarily) have domain knowledge in classroom robot technologies, and can promote them to articulate ideas and views about the prospective attributes in terms of physical appearance, contextual behavior, and social interaction.
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| 7. |
- Tombuloglu, Huseyin, et al.
(författare)
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The size of iron oxide nanoparticles determines their translocation and effects on iron and mineral nutrition of pumpkin (Cucurbita maxima L.)
- 2022
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Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 564
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Tidskriftsartikel (refereegranskat)abstract
- The ability of nanoparticles (NPs) to migrate in the plant body is an important issue to ensure that the NPs reach the desired tissue and to be able to select the most efficient NPs for agricultural applications. In this study, the size impact of four different iron oxide NPs (8-10, 18-20, 20-40, and 30-50 nm referred as NP10, NP20, NP30, and NP40, respectively) on their translocation in pumpkin was elucidated. To assess the root-to-shoot trans -location, phloem sap was examined under transmission electron microscope (TEM). In addition, vibrating sample magnetometer (VSM) and inductively coupled plasma optical emission spectrophotometry (ICP-OES) analyses of stem and leaf tissues were performed to confirm size-dependent translocation. TEM and VSM analyses verified root-to-stem translocation of all tested NPs. The NPs treatment significantly altered the abundances of Mn, Cu, K, P, Al, Mg, and Na in tissues. The iron (Fe) content was abundant in plants treated with NP30 and NP20, and the lowest in plants treated with NP10 and NP40. Together with, only NP30 was found to be significantly trans -located to the leaves, where it was 393 mg/kg in DW, about 2.3 times that of control. These findings pointed out the size-dependent translocation of NPs. It seems that biological barriers in the vascular bundle appear to restrict the migration, especially for NPs with an average size of 40 nm and above in pumpkins. These findings are important for selecting the most suitable size of iron oxide NPs for use in agricultural practices.
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