| 1. |
- Dong, Yibo, et al.
(author)
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Transfer-free, lithography-free and fast growth of patterned CVD graphene directly on insulators by using sacrificial metal catalyst
- 2018
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In: Nanotechnology. - : IOP Publishing. - 1361-6528 .- 0957-4484. ; 29:36
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Journal article (peer-reviewed)abstract
- Chemical vapor deposited graphene suffers from two problems: transfer from metal catalysts to insulators, and photoresist induced degradation during patterning. Both result in macroscopic and microscopic damages such as holes, tears, doping, and contamination, translated into property and yield dropping. We attempt to solve the problems simultaneously. A nickel thin film is evaporated on SiO2 as a sacrificial catalyst, on which surface graphene is grown. A polymer (PMMA) support is spin-coated on the graphene. During the Ni wet etching process, the etchant can permeate the polymer, making the etching efficient. The PMMA/graphene layer is fixed on the substrate by controlling the surface morphology of Ni film during the graphene growth. After etching, the graphene naturally adheres to the insulating substrate. By using this method, transfer-free, lithography-free and fast growth of graphene realized. The whole experiment has good repeatability and controllability. Compared with graphene transfer between substrates, here, no mechanical manipulation is required, leading to minimal damage. Due to the presence of Ni, the graphene quality is intrinsically better than catalyst-free growth. The Ni thickness and growth temperature are controlled to limit the number of layers of graphene. The technology can be extended to grow other two-dimensional materials with other catalysts.
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| 2. |
- Li, Kailun, et al.
(author)
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Crack suppression in additively manufactured tungsten by introducing secondary-phase nanoparticles into the matrix
- 2019
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In: International journal of refractory metals & hard materials. - : Elsevier BV. - 0263-4368. ; 79, s. 158-163
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Journal article (peer-reviewed)abstract
- In this study, an effective strategy was developed to suppress cracking by introducing secondary-phase ZrC nanoparticles into a tungsten (W) matrix. Pure W and W-0.5wt%ZrC bulks were additively manufactured via the laser powder bed fusion (LPBF) technique, and their cracking behaviour was compared. It was observed that the crack density of W-ZrC was reduced by 88.7% compared with that of pure W. The grains in W-ZrC were obviously refined compared with the grains in pure W, which significantly increased the cracking resistance. In addition, ZrC diminished the oxygen impurities, further increasing the cracking resistance. This study provides a promising strategy for the additive manufacturing of high-quality W by introducing secondary-phase nanoparticles into the metal matrix.
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| 3. |
- Olsén, Jon, 1983-, et al.
(author)
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Tailoring hierarchical structures in selective laser melted materials
- 2017
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In: IOP Conference Series. - : Institute of Physics (IOP).
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Conference paper (peer-reviewed)abstract
- With selective laser melting the potential to manufacture a wide variety of geometries from different materials has presented itself. Interest in this technology keeps growing every year, and with that growth a deeper understanding of the process and resulting materials is urgently needed. In this paper we present a short overview of the structural elements that appear during selective laser melting, and explain how to tailor them to achieve specific structures and material properties. Melt-pools, texture and grains, subgrain cells, and inclusions are the elements discussed herein, and tailoring of these elements can have effects on density, and corrosion resistance, as well as mechanical properties in general.
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| 4. |
- Wu, Yongxin, et al.
(author)
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Optical simulation and experimental optimization of Al/NbMoN/NbMoON/SiO2 solar selective absorbing coatings
- 2015
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In: Solar Energy Materials and Solar Cells. - : Elsevier BV. - 0927-0248 .- 1879-3398. ; 134, s. 373-380
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Journal article (peer-reviewed)abstract
- For the applications in solar thermal power, the preparation and optimization of an Al/NbMoN/NbMoON/SiO2 multilayer solar selective absorbing coating are carried out by combining experiments with optical simulation. A series of NbMoN and NbMoON single layers are deposited by magnetron reactive sputtering method with different N-2/O-2 gas flowing rates. And then their optical constants are obtained by fitting their reflection (R) and transmission (T) spectra in the wavelength range of 300-2500 nm using SCOUT software. These optical constants are used to design the Al/NbMoN/NbMoON/SiO2 solar selective absorbing coating so as to get the ideal spectral selectivity, i.e. high alpha/epsilon ratio. According to the optical design of the coating structure, we prepared the all-layer coating, and the thickness of each layer was optimized until the best spectral selective properties are obtained. The experimental reflectance spectrum fits very well with the simulated result. The optimized solar absorbing coating deposited on stainless steel substrate exhibited high absorptance (alpha=0.948) and low emittance (epsilon=0.050) at 80 degrees C. It offers a good method to quickly reach the ideal spectral selectivity through optical simulation. The thermal stability of the coating is evaluated, and it exhibits a good thermal stability in vacuum at 400 degrees C.
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| 5. |
- Wu, Yongxin, et al.
(author)
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Study on the thermal stability of Al/NbTiSiN/NbTiSiON/SiO2 solar selective absorbing coating
- 2015
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In: Solar Energy. - : Elsevier BV. - 0038-092X .- 1471-1257. ; 119, s. 18-28
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Journal article (peer-reviewed)abstract
- In this work, the NbTiSiN and NbTiSiON layers are used instead of NbTiN and NbTiON layers to further improve the thermal stability of Al/NbTiN/NbTiON/SiO2 multilayer solar selective absorbing coating. The thermal stability of Si-doped individual layers and multilayer coatings are investigated. The X-ray diffraction (XRD) results show that Si incorporation into NbTiN (NbTiSiN) layer does not change its preferred orientation, and the Si-doped NbTiON (NbTiSiON) layer remains in amorphous phase. On the other hand, by introducing Si into NbTiN and NbTiON layers induce significant improvement of the oxidation resistance at 500 degrees C in air. After ageing in air at 500 degrees C for 2 h, the absorptance and emittance (at 400 degrees C) of Al/NbTiN/NbTiON/SiO2 and Al/NbTiSiN/NbTiSiON/SiO2 multilayer coatings change from 0.934/0.13 and 0.931/0.12 to 0.538/0.14 and 0.922/0.13, respectively. Meanwhile the surface roughness increases from 18.3 and 7.9 to 41.5 and 14.7 respectively, as atomic force microscopy (AFM) shows. The Al/NbTiSiN/NbTiSiON/SiO2 coating still has a high absorptance (0.910) and low emittance (0.13, at 400 degrees C) after ageing at 550 degrees C in vacuum for 100 h. It displays that Si-doping play an important role in the improvement of the thermal stability.
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| 6. |
- Ye, Xiaoling, et al.
(author)
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High Performance Self-Powered Photodetectors Based on Graphene Nanoribbons/Al2O3/InGaZnO Heterojunctions
- 2024
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In: IEEE Photonics Journal. - : Institute of Electrical and Electronics Engineers (IEEE). - 1943-0655. ; 16:3
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Journal article (peer-reviewed)abstract
- Self-powered photodetectors which operate without external power sources hold immense promise in future photodetection systems. To achieve high-performance self-powered optoelectronic devices, efficient electron-hole pair separation is critical to generate high photocurrents. In this work, we successfully synthesized semiconducting graphene nanoribbons (GNRs) with a direct bandgap of 1.80 eV and employed them to construct a high-performance GNR/Al2O3/IGZO heterostructure photodetector. The built-in electric field in the heterojunctions enables this photodetector to exhibit remarkable performance, showing a responsivity of up to 68 mA/W, a detectivity of 8.34 x 1010 Jones, and rapid response times of 21/20 ms at zero bias. Furthermore, the photodetector features a wide spectral detection range of 405 to 1550 nm. These results highlight the promising potential of GNR/IGZO p-n heterojunction-based self-powered photodetectors in optoelectronic applications.
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| 7. |
- Almqvist, Jonas, et al.
(author)
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Docking and homology modeling explain inhibition of the human vesicular glutamate transporters
- 2007
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In: Protein Science. - 0961-8368 .- 1469-896X. ; 16:9, s. 1819-1829
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Journal article (peer-reviewed)abstract
- As membrane transporter proteins, VGLUT1-3 mediate the uptake of glutamate into synaptic vesicles at presynaptic nerve terminals of excitatory neural cells. This function is crucial for exocytosis and the role of glutamate as the major excitatory neurotransmitter in the central nervous system. The three transporters, sharing 76% amino acid sequence identity in humans, are highly homologous but differ in regional expression in the brain. Although little is known regarding their three- dimensional structures, hydropathy analysis on these proteins predicts 12 transmembrane segments connected by loops, a topology similar to other members in the major facilitator superfamily, where VGLUT1-3 have been phylogenetically classified. In this work, we present a three- dimensional model for the human VGLUT1 protein based on its distant bacterial homolog in the same superfamily, the glycerol- 3-phosphate transporter from Escherichia coli. This structural model, stable during molecular dynamics simulations in phospholipid bilayers solvated by water, reveals amino acid residues that face its pore and are likely to affect substrate translocation. Docking of VGLUT1 substrates to this pore localizes two different binding sites, to which inhibitors also bind with an overall trend in binding affinity that is in agreement with previously published experimental data.
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| 8. |
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| 9. |
- Chen, Jinhan, et al.
(author)
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The effect of hot isostatic pressing on thermal conductivity of additively manufactured pure tungsten
- 2020
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In: International journal of refractory metals & hard materials. - : Elsevier BV. - 0263-4368. ; 87
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Journal article (peer-reviewed)abstract
- The crack-healing behaviors and microstructure evolution of pure tungsten produced by laser powder bed fusion (LPBF) were studied and compared before and after post hot isostatic pressing (post-HIP) treatment. An average thermal conductivity of 133 W.m(-1).K-1 at room temperature (RT) was obtained after HIP, which was 16% higher than that of as-built sample (115 W.m(-1).K-1). Although the HIP process had little effect on density, it resulted in a large grain size of > 300 mu m accompanied by a decrease in dislocation density and crack healing, which led to a substantial improvement of thermal conductivity of pure tungsten. The positive correlation between relative density and thermal conductivity of as-built tungsten was reported.
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| 10. |
- Dong, Y. B., et al.
(author)
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Transfer-free, lithography-free, and micrometer-precision patterning of CVD graphene on SiO 2 toward all-carbon electronics
- 2018
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In: APL Materials. - : AIP Publishing. - 2166-532X. ; 6:2
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Journal article (peer-reviewed)abstract
- A method of producing large area continuous graphene directly on SiO 2 by chemical vapor deposition is systematically developed. Cu thin film catalysts are sputtered onto the SiO 2 and pre-patterned. During graphene deposition, high temperature induces evaporation and balling of the Cu, and the graphene "lands onto" SiO 2 . Due to the high heating and growth rate, continuous graphene is largely completed before the Cu evaporation and balling. 60 nm is identified as the optimal thickness of the Cu for a successful graphene growth and μm-large feature size in the graphene. An all-carbon device is demonstrated based on this technique.
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