| 1. |
- Wicklein, Bernd, et al.
(författare)
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Functional hybrids based on biogenic nanofibrils and inorganic nanomaterials
- 2013
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 1:18, s. 5469-5478
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Tidskriftsartikel (refereegranskat)abstract
- This feature article reviews some of the recent work on the fabrication of functional hybrids based on biogenic nanofibers and inorganic nanomaterials with an emphasis on their functional properties and suggested potential applications. We also discuss some of the work oriented towards the formation of ordered materials in the pursuit of achieving a hierarchical construction. Besides the academic interest in biogenic nanomaterials, it is anticipated that the use of natural, abundant nanomaterials, e.g., cellulose, chitin, collagen, and silk, could provide affordable functional nanomaterials in developing countries.
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| 2. |
- Seisenbaeva, Gulaim, et al.
(författare)
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Solution Equilibrium behind the Room-Temperature Synthesis of Nanocrystalline Titanium Dioxide
- 2013
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Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3364 .- 2040-3372. ; 5, s. 3330-3336
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Tidskriftsartikel (refereegranskat)abstract
- Formation of nanocrystalline and monodisperse TiO ammonium oxo-lactato-titanate, (NH demonstrated to be due to a coordination equilibrium. This compound, individual in the solid state, exists in solution in equilibrium with ammonium tris-lactato-titanate, (NH crystalline TiO equilibrium can be shifted towards nano-TiO ethanol, dilution of the solution, introduction of salts or raising the temperature, and reverted on addition of polar and strongly solvating media such as dimethyl sulfoxide, according to NMR. Aggregation and precipitation of the particles were followed by DLS and could be achieved by a decrease in their surface charge by adsorption of strongly hydrogen-bonding cations, ammonia, ethanolamine or amino acid arginine or by addition of ethanol. The observed equilibrium may be involved in formation of nano-titania on the surface of plant roots exerting chelating organic carboxylate ligands and thus potentially in2 from a water soluble and stable precursor,4)8Ti4O4(Lactate)8$4H2O, often referred to as TiBALDH or TALH, is4)2Ti(Lactate)3 and uniform2 nanoparticles (anatase) stabilized by surface-capping with lactate ligands. This2 via application of a less polar solvent like methanol ore.g. in solutions offluencing plant interactions.
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| 3. |
- Menzel, Carolin, et al.
(författare)
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Molecular structure of citric acid cross-linked starch films
- 2013
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Ingår i: Carbohydrate Polymers. - Amsterdam : Elsevier. - 0144-8617 .- 1879-1344. ; 96:2, s. 270-276
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Tidskriftsartikel (refereegranskat)abstract
- The effect of citric acid (CA) on starch films has been examined. A new method to detect cross-linkingof starch by CA in solution-cast films by molecular weight measurements is described. Furthermore, wemanaged to distinguished between free, mono- and di-esterified CA and quantify di-ester content withinstarch films by using a modification in the method of complexometric titration with copper(II)-sulfate.Cross-linking of starch by CA occurred at low temperature, 70◦C, which we assumed is so far the lowesttemperature reported where cross-linking reaction occurred. This is essential for starch coating applica-tions within paper industry since no high temperatures for curing will be required. However, curing at150◦C and high CA concentrations, 30 pph, increased cross-linking reaction. Furthermore, the physicalproperties like water solubility, gel content and glass transition temperature, were highly reflected bychanges in the molecular structure i.e. cross-linking and hydrolysis, as well as CA content and curingtemperature.
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| 4. |
- Almkvist, Gunnar, et al.
(författare)
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Prediction of tensile strength in iron-contaminated archaeological wood by FT-IR spectroscopy - a study of degradation in recent oak and Vasa oak
- 2016
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Ingår i: Holzforschung. - : Walter de Gruyter GmbH. - 0018-3830 .- 1437-434X. ; 70:9, s. 855-865
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Tidskriftsartikel (refereegranskat)abstract
- Oak from the Swedish warship Vasa and recent oak that was aged after impregnation with iron(II) chloride has been analyzed by FT-IR spectroscopy and submitted to tensile strength testing. The aim was to investigate correlations between FT-IR bands in the fingerprint region, chemical degradation, and tensile strength in iron contaminated oak. The concentration of carboxylic functions increased and the acetyl groups in the hemicellulose fraction were decreasing as a function of degradation time. These changes are accompanied by reduced tensile strength and elevated content of oxalic acid (OA) in both Vasa wood and the impregnated recent oak samples. To evaluate the possibility to predict tensile strength from spectral data, chemometric modeling by partial least-squares (PLS) regression was applied. The strategy of repeated double cross validation (rdCV) allowed a realistic prediction of tensile strength. Overall, chemical changes and mechanical performances of iron contaminated wood are strongly correlated and thus FT-IR spectroscopy is suited to predict the strength properties of the degraded wood.
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| 5. |
- Chen, Tianyang, et al.
(författare)
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High-rate, high-capacity electrochemical energy storage in hydrogen-bonded fused aromatics
- 2023
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Ingår i: Joule. - : Elsevier BV. - 2542-4351. ; 7:5, s. 986-1002
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Tidskriftsartikel (refereegranskat)abstract
- Designing materials for electrochemical energy storage with short charging times and high charge capacities is a longstanding challenge. The fundamental difficulty lies in incorporating a high density of redox couples into a stable material that can efficiently conduct both ions and electrons. We report all-organic, fused aromatic materials that store up to 310 mAh g−1 and charge in as little as 33 s. This performance stems from abundant quinone/imine functionalities that decorate an extended aromatic backbone, act as redox-active sites, engage in hydrogen bonding, and enable a delocalized high-rate energy storage with stability upon cycling. The extended conjugation and hydrogen-bonding-assisted bulk charge storage contrast with the surface-confined or hydration-dependent behavior of traditional inorganic electrodes.
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| 6. |
- Fall, Andreas B., et al.
(författare)
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A physical cross-linking process of cellulose nanofibril gels with shear-controlled fibril orientation
- 2013
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Ingår i: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-683X .- 1744-6848. ; 9:6, s. 1852-1863
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Tidskriftsartikel (refereegranskat)abstract
- Cellulose nanofibrils constitute the smallest fibrous components of wood, with a width of approximately 4 nm and a length in the micrometer range. They consist of aligned linear cellulose chains with crystallinity exceeding 60%, rendering stiff, high-aspect-ratio rods. These properties are advantageous in the reinforcement components of composites. Cross-linked networks of fibrils can be used as templates into which a polymer enters. In the semi-concentrated regime (i.e. slightly above the overlap concentration), carboxy methylated fibrils dispersed in water have been physically cross-linked to form a volume-spanning network (a gel) by reducing the pH or adding salt, which diminishes the electrostatic repulsion between fibrils. By applying shear during or after this gelation process, we can orient the fibrils in a preferred direction within the gel, for the purpose of fully utilizing the high stiffness and strength of the fibrils as reinforcement components. Using these gels as templates enables precise control of the spatial distribution and orientation of the dispersed phase of the composites, optimizing the potentially very large reinforcement capacity of the nanofibrils.
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| 7. |
- Kessler, Vadim
(författare)
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Facile non-hydrolytic synthesis of highly water dispersible, surfactant free nanoparticles of synthetic MFe2O4 (M-Mn2+, Fe2+, Co2+, Ni2+) ferrite spinel by a modified Bradley reaction
- 2013
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 3, s. 12230-12243
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Tidskriftsartikel (refereegranskat)abstract
- A series of the highly crystalline MFe2O4 ferrite spinel nanoparticles were synthesized via a modified Bradley reaction using microwave stimulation. Particle size was estimated using theoretical calculations from the X-ray data (Scherrer and Rietveld methods) as well as by direct experimental techniques such as TEM, DLS and NTA. The calculated average grain size for dry powders is in the range 10 to 23 nm. Hydrodynamic size was measured using DLS on non-modified, surfactant free particles of the whole MFe2O4 series. Raman spectra used for additional verification of the structure features of the produced spinel phases showed strong asymmetric behavior of the A(1g) mode, which was deconvoluted revealing additional components. Among all the products the lowest site inversion was found for the manganese ferrite (MnFe2O4). The oxidation of Fe3O4 leading to the formation of the Fe2O3 hematite phase induced by laser irradiation was observed. Magnetic characterization of the MFe2O4 family was carried out, showing that superparamagnetic blocking temperatures and calculated anisotropy constants K are in good agreement with the data for similar fine-particle systems.
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| 8. |
- Pedersen, Nanna Bjerregaard, et al.
(författare)
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Correlation between bacterial decay and chemical changes in waterlogged archaeological wood analysed by light microscopy and Py-GC/MS
- 2021
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Ingår i: Holzforschung. - : Walter de Gruyter GmbH. - 0018-3830 .- 1437-434X. ; 75:7, s. 635-45
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Tidskriftsartikel (refereegranskat)abstract
- © 2020 Nanna Bjerregaard Pedersen et al., published by De Gruyter, Berlin/Boston 2020. Erosion bacteria are the main degraders of archaeological wood excavated from waterlogged environments. Light microscopy and analytical pyrolysis coupled with gas chromatography/mass spectrometry (Py-GC/MS) were exploited to study waterlogged archaeological wood (Pinus sylvestris L.) at different stages of bacterial decay. The research explored the biochemical changes related to erosion bacteria degradation of the secondary cell wall in the wood cells and the chemical changes related to abiotic processes induced by the long-term waterlogged burial environment. Erosion bacteria were demonstrated by chemical analysis to cause significant holocellulose depletion. Detailed analysis of the holocellulose and lignin pyrolysis products revealed only minor chemical changes in the residual structure even after heavy erosion bacteria decay. Chemical changes in the lignin polymer is associated to enzymatic unlocking of the lignocellulose to gain access to the holocellulose fraction of the cell wall. Chemical changes in the holocellulose fraction are suggested to stem from depolymerisation and from alterations in the polymer matrix of the residual wood cell wall structure. Interestingly, a difference was observed between the sound reference wood and the waterlogged archaeological wood without erosion bacteria decay, indicating that long-term exposure in waterlogged environments results in partial decay of the holocellulose even in absence of bacterial activity.
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| 9. |
- van Chinh, Tran, et al.
(författare)
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Utilizing native lignin as redox-active material in conductive wood for electronic and energy storage applications
- 2022
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 10:29, s. 15677-15688
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Tidskriftsartikel (refereegranskat)abstract
- Nanostructured wood veneer with added electroactive functionality combines structural and functional properties into eco-friendly, low-cost nanocomposites for electronics and energy technologies. Here, we report novel conducting polymer-impregnated wood veneer electrodes where the native lignin is preserved, but functionalized for redox activity and used as an active component. The resulting electrodes display a well-preserved structure, redox activity, and high conductivity. Wood samples were sodium sulfite-treated under neutral conditions at 165 °C, followed by the tailored distribution of PEDOT:PSS, not previously used for this purpose. The mild sulfite process introduces sulfonic acid groups inside the nanostructured cell wall, facilitating electrostatic interaction on a molecular level between the residual lignin and PEDOT. The electrodes exhibit a conductivity of up to 203 S m−1 and a specific pseudo-capacitance of up to 38 mF cm−2, with a capacitive contribution from PEDOT:PSS and a faradaic component originating from lignin. We also demonstrate an asymmetric wood pseudo-capacitor reaching a specific capacitance of 22.9 mF cm−2 at 1.2 mA cm−2 current density. This new wood composite design and preparation scheme will support the development of wood-based materials for use in electronics and energy storage.
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| 10. |
- Abdollahi, Mehdi, 1985
(författare)
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Comparing physico-mechanical and thermal properties of alginate nanocomposite films reinforced with organic and/or inorganic nanofillers
- 2013
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Ingår i: Food Hydrocolloids. - : Elsevier BV. - 0268-005X. ; 32:2, s. 416-424
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Tidskriftsartikel (refereegranskat)abstract
- Montmorillonite (MMT) and cellulose nanoparticles (CNP) were added to alginate biopolymer to compare the properties of bionanocomposites reinforced with different organic and inorganic nanofillers in various loading contents (1, 3, and 5 wt%). Both MMT and CNP decreased the water solubility (WS) of the films. However, at all filler contents the WS of the alginate/MMT (84–61%) nanocomposites was significantly (P < 0.05) lower than that of alginate/CNP films (95–77%). Surface hydrophobicity of the nanocomposites showed a great improvement (83%) with crystalline hydrophobic CNP addition, while MMT made films' surface more hydrophilic. The addition of both nanoreinforcements similarly caused a reduction in the water vapor permeability of the alginate-based nanocomposites. Due to the similar polysaccharide structures and good interfacial interactions, the TS and E of the nanocomposite films improved with an increase in CNP content and reached a maximum at the highest loading level (5 wt%). However, when the content of MMT went beyond 1 wt% nanocomposites, a decrease in the TS was observed. Finally, these results propose that organic CNP more than ability to make a fully renewable and natural nanocomposites may also introduce some other advantages compared to inorganic nanoclay fillers when added to carbohydrate biopolymers.
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