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| 2. |
- Kamada, Ayaka, et al.
(författare)
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Hierarchical propagation of structural features in protein nanomaterials
- 2022
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Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3372 .- 2040-3364. ; 14:6, s. 2502-2510
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Tidskriftsartikel (refereegranskat)abstract
- Natural high-performance materials have inspired the exploration of novel materials from protein building blocks. The ability of proteins to self-organize into amyloid-like nanofibrils has opened an avenue to new materials by hierarchical assembly processes. As the mechanisms by which proteins form nanofibrils are becoming clear, the challenge now is to understand how the nanofibrils can be designed to form larger structures with defined order. We here report the spontaneous and reproducible formation of ordered microstructure in solution cast films from whey protein nanofibrils. The structural features are directly connected to the nanostructure of the protein fibrils, which is itself determined by the molecular structure of the building blocks. Hence, a hierarchical assembly process ranging over more than six orders of magnitude in size is described. The fibril length distribution is found to be the main determinant of the microstructure and the assembly process originates in restricted capillary flow induced by the solvent evaporation. We demonstrate that the structural features can be switched on and off by controlling the length distribution or the evaporation rate without losing the functional properties of the protein nanofibrils.
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| 3. |
- Liu, Sirui, et al.
(författare)
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Design of Hygroscopic Bioplastic Products Stable in Varying Humidities
- 2023
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Ingår i: Macromolecular materials and engineering. - : Wiley. - 1438-7492 .- 1439-2054. ; 308:2
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Tidskriftsartikel (refereegranskat)abstract
- Hygroscopic biopolymers like proteins and polysaccharides suffer from humidity-dependent mechanical properties. Because humidity can vary significantly over the year, or even within a day, these polymers will not generally have stable properties during their lifetimes. On wheat gluten, a model highly hygroscopic biopolymer material, it is observed that larger/thicker samples can be significantly more mechanically stable than thinner samples. It is shown here that this is due to slow water diffusion, which, in turn, is due to the rigid polymer structure caused by the double-bond character of the peptide bond, the many bulky peptide side groups, and the hydrogen bond network. More than a year is required to reach complete moisture saturation (≈10 wt.%) in a 1 cm thick plate of glycerol-plasticized wheat gluten, whereas this process takes only one day for a 0.5 mm thick plate. The overall moisture uptake is also retarded by swelling-induced mechanical effects. Hence, hygroscopic biopolymers are better suited for larger/thicker products, where the moisture-induced changes in mechanical properties are smeared out over time, to the extent that the product remains sufficiently tough over climate changes, for example, throughout the course of a year.
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| 4. |
- Bi, Zhaozhao, et al.
(författare)
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Individual nanostructure optimization in donor and acceptor phases to achieve efficient quaternary organic solar cells
- 2019
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Ingår i: Nano Energy. - : ELSEVIER. - 2211-2855 .- 2211-3282. ; 66
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Tidskriftsartikel (refereegranskat)abstract
- Fullerene derivative (PC71BM) and high crystallinity molecule (DR3TBDTT) are employed into PTB7-Th:FOIC based organic solar cells (OSCs) to cooperate an individual nanostructure optimized quaternary blend. PC71BM functions as molecular adjuster and phase modifier promoting FOIC forming "head-to-head" molecular packing and neutralizing the excessive FOIC crystallites. A multi-scale modified morphology is present thanks to the mixture of FOIC and PC71BM while DR3TBDTT disperses into PTB7-Th matrix to reinforce donors crystal-linity and enhance domain purity. Morphology characterization highlights the importance of individually optimizated nanostructures for donor and acceptor, which contributes to efficient hole and electron transport toward improved carrier mobilities and suppressed non-geminated recombination. Therefore, a power conversion efficiency of 13.51% is realized for a quaternary device which is 16% higher than the binary device (PTB7-Th:FOIC). This work demonstrates that utilizing quaternary strategy for simultaneous optimization of donor and acceptor phases is a feasible way to realize high efficient OSCs.
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| 5. |
- Guo, Sihua, et al.
(författare)
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Toward ultrahigh thermal conductivity graphene films
- 2023
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Ingår i: 2D Materials. - : IOP Publishing. - 2053-1583. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- With increasing demands of high-performance and functionality, electronics devices generate a great amount of heat. Thus, efficient heat dissipation is crucially needed. Owing to its extremely good thermal conductivity, graphene is an interesting candidate for this purpose. In this paper, a two-step temperature-annealing process to fabricate ultrahigh thermal conductive graphene assembled films (GFs) is proposed. The thermal conductivity of the obtained GFs was as high as 3826 +/- 47 W m(-1) K-1. Extending the time of high-temperature annealing significantly improved the thermal performance of the GF. Structural analyses confirmed that the high thermal conductivity is caused by the large grain size, defect-free stacking, and high flatness, which are beneficial for phonon transmission in the carbon lattice. The turbostratic stacking degree decreased with increasing heat treatment time. However, the increase in the grain size after long heat treatment had a more pronounced effect on the phonon transfer of the GF than that of turbostratic stacking. The developed GFs show great potential for efficient thermal management in electronics devices.
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| 6. |
- Wei, Xinfeng, et al.
(författare)
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Long-term performance of polyamide-based multilayer (bio)diesel fuel lines aged under “in-vehicle” conditions
- 2017
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Ingår i: Polymer degradation and stability. - : Elsevier. - 0141-3910 .- 1873-2321. ; 144, s. 100-109
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Tidskriftsartikel (refereegranskat)abstract
- The behaviour of a polyamide (PA)-based multilayer fuel pipe was investigated in “close to real” conditions using specially-designed ageing equipment with a program designed according to known customer driving modes and conditions (a key life test). The pipe was exposed to petroleum diesel and a combination of petroleum diesel and biodiesel. The fuel exposure pattern, as well as the temperature profile, followed a specified scheme in the key life test. It allowed for the investigation and understanding of complex ageing mechanisms, often observed in multi-layer systems with a variation in the running conditions. The mechanisms involved included migration of plasticizer from the innermost PA6 layer of the pipe to the fuel, and from the PA12 outer layer to the ambient air. At the same time, fuel was absorbed in the inner layer of the pipe. The oxidation of the innermost PA6 layer was promoted by the oxidation products of biodiesel. The diffusion-limited oxidation of the PA6 layer led to the formation of a 30 μm highly oxidized zone at the inner surface of the pipe, resulting in discoloration and oxidative crosslinking of the polymer. The toughness and extensibility of the pipe decreased significantly after prolonged ageing, and the extensibility was only 7% of that of the unaged pipe after 2230 h.
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| 7. |
- Zhou, Ke, et al.
(författare)
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Molecular and Energetic Order Dominate the Photocurrent Generation Process in Organic Solar Cells with Small Energetic Offsets
- 2020
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Ingår i: ACS Energy Letters. - : AMER CHEMICAL SOC. - 2380-8195. ; 5:2, s. 589-596
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Tidskriftsartikel (refereegranskat)abstract
- Minimizing the energetic offset between the donor (D) and acceptor (A) in organic solar cells (OSCs) is pivotal for reducing the charge-transfer (CT) loss and improving the open-circuit voltage (V-oc). This nevertheless leads to a topic of debate regarding the driving force for the charge separation in OSCs with small energetic offsets. The molecular packing geometries in the active layer determine the energetic levels and trap density, but their relationship with the driving force is seldom considered. Limited by the complicated demixing morphology and inaccurate measurements of energy levels in the prototypical bulk-heterojunction (BHJ) devices, we thereby demonstrate a concise and robust planar-heterojunction model of PM7/N2200 to investigate the origin of driving force for charge generation. It is surprising to note that the device with smaller energy offset shows higher efficiency. Further analysis reveals that a bilayer device with short-range packing PM7 exhibits smaller energetic offsets along with fewer morphological defects and traps compared to its long-range packing counterparts. This molecular packing characteristic diminishes the energetic disorder at the D/A interfaces and inhibits the trap-assisted charge recombination, contributing to the increased short-circuit current (J(SC)) and V-OC. Our results suggest that the energetic offset actually has limited influence on charge separation, while the synergetic control of molecular and energetic order is vital to the photocurrent generation and energy loss reduction in OSCs.
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