| 1. |
- Liu, Ya, 1991, et al.
(författare)
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A Novel Graphene Quantum Dot-Based mRNA Delivery Platform
- 2021
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Ingår i: ChemistryOpen. - : Wiley. - 2191-1363. ; 10:7, s. 666-671
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Tidskriftsartikel (refereegranskat)abstract
- During the last decades, there has been growing interest in using therapeutic messager RNA (mRNA) together with drug delivery systems. Naked, unformulated mRNA is, however, unable to cross the cell membrane and is susceptible to degradation. Here we use graphene quantum dots (GQDs) functionalized with polyethyleneimine (PEI) as a novel mRNA delivery system. Our results show that these modified GQDs can be used to deliver intact and functional mRNA to Huh-7 hepatocarcinoma cells at low doses and, that the GQDs are not toxic, although cellular toxicity is a problem for these first-generation modified particles. Functionalized GQDs represent a potentially interesting delivery system that is easy to manufacture, stable and effective.
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| 2. |
- Wang, Nan, et al.
(författare)
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Highly Thermal Conductive and Light -weight Craphene-based Heatsink
- 2019
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Ingår i: 2019 22ND EUROPEAN MICROELECTRONICS AND PACKAGING CONFERENCE & EXHIBITION (EMPC). - 2165-2341. - 9780956808660
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Konferensbidrag (refereegranskat)abstract
- With the developing trend ofminiaturization and integration of modem electronic devices, commercial hearsinks ivaterigh, like copper and ii iv are facing mare and mare challenges, such as inefficient cooling performance, large size turd heavy weight. Here, we salve the probletn by developing a novel highly thermal conductive and 11Mo-weight graphene heatsink. Cornposed by vertically-aligned and continUOUS graphene structures, heat transport was highly efficiero from the base 1o fin Ii: ininside the heatsink, The maximum through-platre thermal catuluctivity ofgraphene heatsink can be up to 1000 1500 Ward( which is over 7 times higher than aluminum, and even outperforms copper about 4 times_ Gmphene heatsink demonstrated outstanding cooling perffrmance which wm superior to copper heatsink with the same dimension and same power input. Noticeably, the graphene hearsink also has anportant advantagas of light-weight and high emissions,. The measured density (1 1 g cmli is only onroeighth of copper and lam than hoor of aluminum and emissivity is about ten times hiher than pure rapper and aluminum. The resulting graphene heatsink thus opertS rim opportunities for addressing large heat dissMatMn issues in weight' driven electronics and othm high power smions.
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| 3. |
- Zhang, Zhfei, et al.
(författare)
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Characterization of CNT Enhanced Conductive Adhesives in Terms of Thermal Conductivity
- 2012
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Ingår i: ECS Transactions. - : The Electrochemical Society. - 1938-5862 .- 1938-6737. - 9781607683186 ; 44:1, s. 1011-1017
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Konferensbidrag (refereegranskat)abstract
- CNTs have excellent thermal, electrical and mechanical properties. They can be used in various ways. One researched field of application is CNT-polymer composites which combine common technologies with advanced materials. This paper will focus on the thermal property of CNT-Ag-filled adhesives and compares the new materials with conventional, electrical Ag-filled conductive adhesives. Several analytical methods, FTIR, Raman analysis, SEM and TEM have been carried out to examine the different surface conditions after physicval and chemical modification of CNTs. The thermal conductivities of composites containing different types of CNTs were investigated. The incorporation of CNTs into polymers resulted in enhancement of the thermal conductivity compared to Ag-filler. The increase of thermal conductivity with addition of CNT filler is obvious, especially for the purified CNT. The value of thermal conductivity is about two times higher than the Ag-filled conductive adhesive. However, improvement on thermal conductivity of the surface modified CNT-filled conductive adhesives is not so obvious. Since the thermal conduction in CNT is by phonon transfer, the nanometric size and the huge interface lead to strong phonon-scattering at the interface. Thus, a relatively low interfacial area, weak interfacial adhesion promotes the conduction of phonons and minimizes coupling losses. According to this, the non-treated MWCNTs seem to have the highest potential to improve the thermal conductivity of epoxies.
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| 4. |
- Bao, Jie, et al.
(författare)
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Synthesis and Applications of Two-Dimensional Hexagonal Boron Nitride in Electronics Manufacturing
- 2016
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Ingår i: Electronic Materials Letters. - : Springer Science and Business Media LLC. - 1738-8090 .- 2093-6788. ; 12:1, s. 1-16
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Forskningsöversikt (refereegranskat)abstract
- In similarity to graphene, two-dimensional (2D) hexagonal boron nitride (hBN) has some remarkable properties, such as mechanical robustness and high thermal conductivity. In addition, hBN has superb chemical stability and it is electrically insulating. 2D hBN has been considered a promising material for many applications in electronics, including 2D hBN based substrates, gate dielectrics for graphene transistors and interconnects, and electronic packaging insulators. This paper reviews the synthesis, transfer and fabrication of 2D hBN films, hBN based composites and hBN-based van der Waals heterostructures. In particular, this review focuses on applications in manufacturing electronic devices where the insulating and thermal properties of hBN can potentially be exploited. 2D hBN and related composite systems are emerging as new and industrially important materials, which could address many challenges in future complex electronics devices and systems.
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| 5. |
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| 6. |
- Duan, Y., et al.
(författare)
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A New Thermally Conductive Thermoplastic Die Attach Film
- 2012
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Ingår i: Proceedings of IEEE CPMT 2012 International Conference on Electronic Packaging Technology & High Density Packaging. - 9781467316804 ; , s. 212-215
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Konferensbidrag (refereegranskat)abstract
- As devices with smaller footprint and, higher functionality become the norm, stacked die technology will be required to enable the advancement of modern integrated packaging. As wafers become ever thinner to meet stacking requirements, new materials technology must address the challenges of handling and processing wafer thicknesses of less than 100 microns. Die attach film (DAF) has being widely used as an alternative. With its good control of bleed, consistent bond line thickness and simplified operation. In this paper, a kind of thermoplastic film with good thermal conductivity was developed for die attachment application and some of its properties, such as shear strength and, thermal conductivity were investigated. In the present work, the formula of the DAF matrix has been determined and in order to improve thermal conductivity of DAF, silicon carbide (SiC) particles with high thermal conductivity were selected to add as filler and in the content of SiC particles on the property of the DAFs were also investigated. Shear tests were conducted to measure the bonding strength of the DAFs. The results show that the films reached a 6.5 MPa in terms of average shear strength and after plasticizing it could reach 3.5 MPa. The thermal conductivity of the DAFs was 0.37W/ m·K.
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| 7. |
- Fazi, Andrea, 1992, et al.
(författare)
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Multiple growth of graphene from a pre-dissolved carbon source
- 2020
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Ingår i: Nanotechnology. - : IOP Publishing. - 1361-6528 .- 0957-4484. ; 31:34, s. 345601-
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Tidskriftsartikel (refereegranskat)abstract
- Mono- to few-layer graphene materials are successfully synthesized multiple times using Cu-Ni alloy as a catalyst after a single-chemical vapor deposition (CVD) process. The multiple synthesis is realized by extracting carbon source pre-dissolved in the catalyst substrate. Firstly, graphene is grown by the CVD method on Cu-Ni catalyst substrates. Secondly, the same Cu-Nicatalyst foils are annealed, in absence of any external carbon precursor, to grow graphene using the carbon atoms pre-dissolved in the catalyst during the CVD process. This annealing process is repeated to synthesize graphene successfully until carbon is exhausted in the Cu-Ni foils. After the CVD growth and each annealing growth process, the as-grown graphene is removed using a bubbling transfer method. A wide range of characterizations are performed to examine the quality of the obtained graphene material and to monitor the carbon concentration in the catalyst substrates. Results show that graphene from each annealing growth process possesses a similar quality, which confirmed the good reproducibility of the method. This technique brings great freedom to graphene growth and applications, and it could be also used for other 2D material synthesis.
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| 8. |
- Fu, Yifeng, 1984, et al.
(författare)
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Carbon nanotube growth on different underlayers for thermal interface material application
- 2016
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Ingår i: IMAPS Nordic Annual Conference 2016 Proceedings. - 9781510827226
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Konferensbidrag (refereegranskat)abstract
- Thermal interface material (TIM) is a critical component in thermal management of high density packaging systems since both the reliability and lifetime of microsystems are dependent on how the heat is dissipated. Carbon nanotubes (CNTs) are promising candidate for development of TIMs due to their excellent thermal and mechanical properties. The thermal conductivity of CNTs can be up to 3000 W/mK in the longitudinal direction which acts as ideal heat transfer path. However, the huge interfacial thermal resistance between CNTs and contact surface hinders the exploitation of CNTs as TIMs. In this paper, we will focus on the growth of CNTs on various substrates and underlayers and analyze the interaction between catalyst and underlayer materials. Microscopic analysis is performed to characterize the quality of the CNT materials and monitor the diffusion of Fe particles into different barrier layers. Thermal conductivity of the CNT TIMs will be measured to examine the performance of the materials.
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| 9. |
- han, Hao xue, et al.
(författare)
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Enhanced Heat Spreader Based on Few-Layer Graphene Intercalated With Silane-Functionalization Molecules
- 2014
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Ingår i: IEEE 20th International Workshop on Thermal Investigation of ICs and Systems (Therminic). Greenwich, London, United Kingdom, 24-26 September 2014. - 9781479954155 ; , s. 1-4
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Konferensbidrag (refereegranskat)abstract
- We studied the heat-spreading enhancement of supported few-layer graphene by inserting silane-functionalization molecules between graphene sheets. We calculated the overall thermal resistance of graphene-substrate interface and the in-plane thermal conductivity of graphene sheets by equilibrium molecular dynamics simulations. We probed the spectral phonon transmission coefficient by non-equilibrium Green's function to characterize the local heat conduction through the interface. Our results show that the overal thermal resistance between the substrate graphene and the upper two-layer graphene underwent a three-fold increase by the presence of the molecules, while the local heat conduction from the hot spot to the graphene sheets through the molecules was largely intensified. Furthermore, the in-plane thermal conductivity of the few-layer graphene increased by 60% compared with the supported graphene non-bonded to the substrate through the molecules. This increase is attributed to the refrained cross-plane phonon scattering which in turn reinforces the in-plane heat conduction of the few-layer graphene. In summary, we proved that by inserting silane-functionalization molecules, the few-layer graphene becomes an ideal candidate for heat spreading by guiding heat more efficiently away from the heat source.
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| 10. |
- Hansson, Josef, 1991, et al.
(författare)
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Effects of high temperature treatment of carbon nanotube arrays on graphite : Increased crystallinity, anchoring and inter-tube bonding
- 2020
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Ingår i: Nanotechnology. - : Institute of Physics Publishing (IOPP). - 0957-4484 .- 1361-6528. ; 31:45
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Tidskriftsartikel (refereegranskat)abstract
- Thermal treatment of carbon nanotubes (CNTs) can significantly improve their mechanical, electrical and thermal properties due to reduced defects and increased crystallinity. In this work we investigate the effect of annealing at 3000 degrees C of vertically aligned CNT arrays synthesized by chemical vapor deposition (CVD) on graphite. Raman measurements show a drastically reduced amount of defects and, together with transmission electron microscope (TEM) diffraction measurements, an increased average crystallite size of around 50%, which corresponds to a 124% increase in Young's modulus. We also find a tendency for CNTs to bond to each other with van der Waals (vdW) forces, which causes individual CNTs to closely align with each other. This bonding causes a densification effect on the entire CNT array, which appears at temperatures >1000 degrees C. The densification onset temperature corresponds to the thermal decomposition of oxygen containing functional groups, which otherwise prevents close enough contact for vdW bonding. Finally, the remaining CVD catalyst on the bottom of the CNT array is evaporated during annealing, enabling direct anchoring of the CNTs to the underlying graphite substrate.
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