| 1. |
- Abbasi Aval, Negar, et al.
(författare)
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An aligned fibrous and thermosensitive hyaluronic acid-puramatrix interpenetrating polymer network hydrogel with mechanical properties adjusted for neural tissue
- 2022
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Ingår i: Journal of Materials Science. - : Springer Nature. - 0022-2461 .- 1573-4803. ; 57:4, s. 2883-2896
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Tidskriftsartikel (refereegranskat)abstract
- Central nervous system (CNS) injuries such as stroke or trauma can lead to long-lasting disability, and there is no currently accepted treatment to regenerate functional CNS tissue after injury. Hydrogels can mimic the neural extracellular matrix by providing a suitable 3D structure and mechanical properties and have shown great promise in CNS tissue regeneration. Here we present successful synthesis of a thermosensitive hyaluronic acid-RADA 16 (Puramatrix (TM)) peptide interpenetrating network (IPN) that can be applied in situ by injection. Thermosensitive hyaluronic acid (HA) was first synthesized by combining HA with poly(N-isopropylacrylamide). Then, the Puramatrix (TM) self-assembled peptide was combined with the thermosensitive HA to produce a series of injectable thermoresponsive IPNs. The HA-Puramatrix (TM) IPNs formed hydrogels successfully at physiological temperature. Characterization by SEM, rheological measurements, enzymatic degradation and swelling tests was performed to select the IPN optimized for neurologic use. SEM images of the optimized dry IPNs demonstrated an aligned porous structure, and the rheological measurements showed that the hydrogels were elastic, with an elastic modulus of approximately 500 Pa, similar to that of brain tissue. An evaluation of the cell-material interactions also showed that the IPN had biological characteristics required for tissue engineering, strongly suggesting that the IPN hydrogel possessed properties beneficial for regeneration of brain tissue.
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| 2. |
- Agbaje, Oluwatoosin B. A., et al.
(författare)
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Biomacromolecules in recent phosphate-shelled brachiopods : identification and characterization of chitin matrix
- 2021
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Ingår i: Journal of Materials Science. - : Springer Nature. - 0022-2461 .- 1573-4803. ; 56:36, s. 19884-19898
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Tidskriftsartikel (refereegranskat)abstract
- Phosphate-shelled brachiopods differ in filter-feeding lifestyle, with Lingula anatina an active infaunal burrower, and Discinisca tenuis a shallow marine epibenthic animal. The shells of these animals are built of organophosphatic constituents, the organic fibres/sheets reinforced with calcium phosphate to provide a sophisticated ultrastructural robustness. This investigation examined the nature of the organic fibres in order to improve understanding of how living organisms produce hierarchically structured biomaterials. Unlike powdered samples commonly used in previous studies, organic fibres were isolated for the first time and the shell fractions were purified, in order to study the content and nature of the biopolymer fibres. Biochemical methods including Calcofluor staining revealed a chitin matrix. Ultrastructural analysis, thermal gravimetric analysis, and spectroscopic analyses show that the core polysaccharide framework is composed of layers of β-chitin sheets and/or fibrils that are coated with a fibrous organic matrix. There is more chitin matrix in the L. anatina shells (26.6 wt.%) compared to the D. tenuis shells (12.9 wt.%). Taken together, the data show that the chitin matrix contributes to increased skeletal strength, making L. anatina highly adapted for life as an active burrower. In comparison, D. tenuis contains less chitin and lives as attached epibenthos in a shallow marine environment.
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| 3. |
- Ali, Sharafat, Associate Professor, 1976-, et al.
(författare)
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Effect of O/N content on the phase, morphology, and optical properties of titanium oxynitride thin films
- 2023
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Ingår i: Journal of Materials Science. - : Springer. - 0022-2461 .- 1573-4803. ; 58, s. 10975-10985
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Tidskriftsartikel (refereegranskat)abstract
- Phase formation, morphology, and optical properties of Ti(O,N) thin films with varied oxygen-to- nitrogen ration content were investigated. The films were deposited by magnetron sputtering at 500°C on Si(100) and c-plane sapphire substrate. A competition between a NaCl B1 structure TiN1-xOx, a rhombohedral structure Ti2(O1-yNy)3, and an anatase structure Ti(O1-zNz)2 phase was observed. While the N-rich films were composed of a NaCl B1 TiN1-xOx phase, an increase of oxygen in the films yields the growth of rhombohedral Ti2(O1-yNy)3 phase and the oxygen-rich films are comprised of a mixture of the rhombohedral Ti2(O1-yNy)3 phase and anatase Ti(O1-zNz)2 phase. The optical properties of the films were correlated to the phase composition and the observation of abrupt changes in terms of refractive index and absorption coefficient. The oxide film became relatively transparent in the visible range while the addition of nitrogen into films increases the absorption. The oxygen rich-samples have bandgap values below 3.75 eV, which is higher than the value for pure TiO2, and lower than the optical bandgap of pure TiN. The optical properties characterizations revealed the possibility of adjusting the band gap and the absorption coefficient depending on the N-content, because of the phases constituting the films combined with anionic substitution.
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| 4. |
- Baghdadchi, Amir, 1994-, et al.
(författare)
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Wire laser metal deposition of 22% Cr duplex stainless steel : as-deposited and heat-treated microstructure and mechanical properties
- 2022
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Ingår i: Journal of Materials Science. - : Springer Science and Business Media LLC. - 0022-2461 .- 1573-4803. ; 57:21, s. 9556-9575
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Tidskriftsartikel (refereegranskat)abstract
- Duplex stainless steel (DSS) blocks with dimensions of 150 × 70x30 mm3 were fabricated by Laser Metal Deposition with Wire (LMDw). Implementation of a programmable logic control system and the hot-wire technology provided a stable and consistent process producing high-quality and virtually defect-free deposits. Microstructure and mechanical properties were studied for as-deposited (AD) material and when heat-treated (HT) for 1 h at 1100 °C. The AD microstructure was inhomogeneous with highly ferritic areas with nitrides and austenitic regions with fine secondary austenite occurring in a periodic manner. Heat treatment produced a homogenized microstructure, free from nitrides and fine secondary austenite, with balanced ferrite and austenite fractions. Although some nitrogen was lost during LMDw, heat treatment or reheating by subsequent passes in AD allowed the formation of about 50% austenite. Mechanical properties fulfilled common requirements on strength and toughness in both as-deposited and heat-treated conditions achieving the highest strength in AD condition and best toughness and ductility in HT condition. Epitaxial ferrite growth, giving elongated grains along the build direction, resulted in somewhat higher toughness in both AD and HT conditions when cracks propagated perpendicular to the build direction. It was concluded that high-quality components can be produced by LMDw and that deposits can be used in either AD or HT conditions. The findings of this research provide valuable input for the fabrication of high-performance DSS AM components
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| 5. |
- Boras, Dominik, et al.
(författare)
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Determining internal porosity in Prussian blue analogue cathode materials using positron annihilation lifetime spectroscopy
- 2023
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Ingår i: Journal of Materials Science. - : Springer Nature. - 0022-2461 .- 1573-4803. ; 58:42, s. 16344-16356
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Tidskriftsartikel (refereegranskat)abstract
- Prussian blue analogues (PBAs), AxM[M’(CN)6]1–y·zH2O, are a highly functional class of materials with use in a broad range of applications, such as energy storage, due to their porous structure and tunable composition. The porosity is particularly important for the properties and is deeply coupled to the cation, water, and [M’(CN)6]n– vacancy content. Determining internal porosity is especially challenging because the three compositional parameters are dependent on each other. In this work, we apply a new method, positron annihilation lifetime spectroscopy (PALS), which can be employed for the characterization of defects and structural changes in crystalline materials. Four samples were prepared to evaluate the method’s ability to detect changes in internal porosity as a function of the cation, water, and [M’(CN)6]n– vacancy content. Three of the samples have identical [M’(CN)6]n– vacancy content and gradually decreasing sodium and water content, while one sample has no sodium and 25% [M’(CN)6]n– vacancies. The samples were thoroughly characterized using inductively coupled plasma-optical emission spectroscopy (ICP-OES), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and Mössbauer spectroscopy as well as applying the PALS method. Mössbauer spectroscopy, XRD, and TGA analysis revealed the sample compositions Na1.8(2)Fe2+0.64(6)Fe2.6+0.36(10)[Fe2+(CN)6]·2.09(2)H2O, Na1.1(2)Fe2+0.24(6)Fe2.8+0.76(6)[Fe2.3+(CN)6]·1.57(1)H2O, Fe[Fe(CN)6]·0.807(9)H2O, and Fe[Fe(CN)6]0.75·1.5H2O, confirming the absence of vacancies in the three main samples. It was shown that the final composition of PBAs could only be unambiguously confirmed through the combination of ICP, XRD, TGA, and Mössbauer spectroscopy. Two positron lifetimes of 205 and 405 ps were observed with the 205 ps lifetime being independent of the sodium, water, and/or [Fe(CN)6]n– vacancy content, while the lifetime around 405 ps changes with varying sodium and water content. However, the origin and nature of the 405 ps lifetime yet remains unclear. The method shows promise for characterizing changes in the internal porosity in PBAs as a function of the composition and further development work needs to be carried out to ensure the applicability to PBAs generally.
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| 6. |
- da Silva, Laura C. E., et al.
(författare)
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Morphological investigation of ternary and semicrystalline organic-inorganic hybrid nanocomposite
- 2022
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Ingår i: Journal of Materials Science. - : Springer Science and Business Media LLC. - 0022-2461 .- 1573-4803. ; 57, s. 6196-6211
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Tidskriftsartikel (refereegranskat)abstract
- Organic–inorganic (O–I) hybrid nanocomposites have already been widely investigated in the optoelectronic industry and are emerging in the biomedical field. In both cases, a thorough knowledge of the O–I hybrid morphology is key for reaching tailored properties of the devices; however, up to now little is known on this matter. Herein, we used advanced X-ray scattering and microscopy techniques to investigate in detail the morphology and nanostructure of a biocompatible, ternary, and semicrystalline O–I hybrid nanocomposite made up of poly(ε-caprolactone) (PCL) and poly(ethylene glycol) (PEG), cross-linked by in situ-generated silsesquioxane structures (SS). Results showed that phase separation occurred at all length scales. At the microscale, irreversible PCL/PEG phase separation generated a globular morphology, where PEG-rich spherical domains were uniformly distributed within a PCL-rich matrix. At the nanoscale, partial organic/inorganic phase segregation resulted in the formation of polysilsesquioxane nanoparticles in both matrix and domains. Finally, an unusual crystalline behaviour was observed for the ternary O–I hybrid nanocomposite, PCL-PEG/SS, where PCL crystallization was anticipated and PEG crystallization was delayed in comparison with the binary PCL/SS and PEG/SS O–I hybrids as well as to a blend of the uncross-linked PCL and PEG precursors. These results provide new insights on how the competing processes of phase separation, crystallization, and inorganic cross-linking affect the overall morphology and nanostructure of O–I hybrid nanocomposites and, therefore, might be useful for establishing relevant structure–property relationships.
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| 7. |
- Dastanpour Hosseinabadi, Esmat, et al.
(författare)
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Multi-alloying of nanomet : conception and implementation of homogeneous nanocrystallization in high-flux density soft magnetic alloys
- 2021
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Ingår i: Journal of Materials Science. - : Springer. - 0022-2461 .- 1573-4803. ; 56:16, s. 10124-10134
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Tidskriftsartikel (refereegranskat)abstract
- This study demonstrates how multi-alloying the Fe-Si–B–P–Cu (Nanomet®) can avoid the strict requirements on the annealing scheme in terms of high heating rate and narrow annealing temperature range in order to grow a homogeneous ultrafine nanocrystalline structure. The rather restricted amorphization capability sets a low limit of the maximum thickness of the amorphous precursor. These shortcomings have their origin in the existence of detrimental pre-existing nuclei in the amorphous precursors, which in turn potentially lead to a heterogeneous crystallization. Here, we have multialloyed Nanomet with CoCNi- and CoCMo- to avoid the creation of these pre-existing nuclei. This leads to improved amorphization capability and changes a potentially heterogeneous crystallization to a homogeneous nanocrystallization over a much broader temperature range than for unalloyed Nanomet. Thus, the requirements for the annealing are much relaxed. This work encompasses quenching the amorphous precursors using melt-spinning, investigating the crystallization temperatures by calorimetry, showing the depletion of pre-existing nuclei by magneto-thermo-gravimetry, conceptualizing the crystallization dynamics using isothermal calorimetry, and finally revealing the excellent soft magnetic properties over a broad annealing temperature interval (390–490 °C for the substituted alloys compared to 410–470 °C for unalloyed Nanomet). The multi-elemental substitution of Fe with CoCMo and CoCNi in Nanomet alloy nearly maintains the saturation magnetization and the coercivity. We believe the substituted alloys provide a better alternative to Nanomet with improved amorphization capability and homogeneous nanocrystallization without any special heat treatment scheme. Graphical abstract: [Figure not available: see fulltext.]
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| 8. |
- Eichhorn, S. J., et al.
(författare)
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Current international research into cellulose as a functional nanomaterial for advanced applications
- 2022
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Ingår i: Journal of Materials Science. - : Springer Nature. - 0022-2461 .- 1573-4803. ; 57:10, s. 5697-5767
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Tidskriftsartikel (refereegranskat)abstract
- This review paper provides a recent overview of current international research that is being conducted into the functional properties of cellulose as a nanomaterial. A particular emphasis is placed on fundamental and applied research that is being undertaken to generate applications, which are now becoming a real prospect given the developments in the field over the last 20 years. A short introduction covers the context of the work, and definitions of the different forms of cellulose nanomaterials (CNMs) that are most widely studied. We also address the terminology used for CNMs, suggesting a standard way to classify these materials. The reviews are separated out into theme areas, namely healthcare, water purification, biocomposites, and energy. Each section contains a short review of the field within the theme and summarizes recent work being undertaken by the groups represented. Topics that are covered include cellulose nanocrystals for directed growth of tissues, bacterial cellulose in healthcare, nanocellulose for drug delivery, nanocellulose for water purification, nanocellulose for thermoplastic composites, nanocellulose for structurally colored materials, transparent wood biocomposites, supercapacitors and batteries.
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| 9. |
- George, S., et al.
(författare)
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Local structure in amorphous Sm x Co 1-x : a combined experimental and theoretical study
- 2020
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Ingår i: Journal of Materials Science. - : Springer. - 0022-2461 .- 1573-4803. ; 55:26, s. 12488-12498
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Tidskriftsartikel (refereegranskat)abstract
- Using a combination of extended X-ray absorption fine structure measurements, stochastic quenching (SQ) calculations and Voronoi tessellation analysis, the local atomic environments in thin films of amorphous Sm$$_{x}$$xCo$$_{1-x}$$1-x ($$x =$$x= 0.10, 0.22 and 0.35) are investigated and also compared with crystalline stoichiometric Sm–Co alloys of similar compositions. It is found that the variations in local environment around Co atoms in the amorphous films increase with increasing x and that none of the films exhibit any pronounced short-range order around the Sm atoms. There are, however, signs of clustering of Sm atoms in the SQ-generated simulated amorphous materials.Furthermore, good agreement is observed between experimentally obtained parameters, e.g., interatomic distances and coordination numbers, and those extracted from the simulated alloys. This is a strong indication that SQ provides a powerful route to reliable local structure information for amorphous rare earth–transition metal alloys and that it could be used for designing materials with properties that meet the demands of specific applications.
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| 10. |
- George, Sebastian, 1990-, et al.
(författare)
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Local structure in amorphous SmxCo1-x : a combined experimental and theoretical study
- 2020
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Ingår i: Journal of Materials Science. - : Springer Science and Business Media LLC. - 0022-2461 .- 1573-4803. ; 55, s. 12488-12498
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Tidskriftsartikel (refereegranskat)abstract
- Using a combination of extended X-ray absorption fine structure measurements, stochastic quenching (SQ) calculations and Voronoi tessellation analysis, the local atomic environments in thin films of amorphous SmxCo1−x (x= 0.10, 0.22 and 0.35) are investigated and also compared with crystalline stoichiometric Sm–Co alloys of similar compositions. It is found that the variations in local environment around Co atoms in the amorphous films increase with increasing x and that none of the films exhibit any pronounced short-range order around the Sm atoms. There are, however, signs of clustering of Sm atoms in the SQ-generated simulated amorphous materials. Furthermore, good agreement is observed between experimentally obtained parameters, e.g., interatomic distances and coordination numbers, and those extracted from the simulated alloys. This is a strong indication that SQ provides a powerful route to reliable local structure information for amorphous rare earth–transition metal alloys and that it could be used for designing materials with properties that meet the demands of specific applications.
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