| 1. |
- Solé-Domènech, Santiago, et al.
(författare)
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Localization of cholesterol, amyloid and glia in Alzheimer's disease transgenic mouse brain tissue using time-of-flight secondary ion mass spectrometry (ToF-SIMS) and immunofluorescence imaging
- 2013
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Ingår i: Acta Neuropathologica. - : Springer Science and Business Media LLC. - 0001-6322 .- 1432-0533. ; 125:1, s. 145-157
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Tidskriftsartikel (refereegranskat)abstract
- The spatial distributions of lipids, amyloid-beta deposits, markers of neurons and glial cells were imaged, at submicrometer lateral resolution, in brain structures of a mouse model of Alzheimer's disease using a new methodology that combines time-of-flight secondary ion mass spectrometry (ToF-SIMS) and confocal fluorescence microscopy. The technology, which enabled us to simultaneously image the lipid and glial cell distributions in Tg2576 mouse brain structures, revealed micrometer-sized cholesterol accumulations in hippocampal regions undergoing amyloid-beta deposition. Such cholesterol granules were either associated with individual amyloid deposits or spread over entire regions undergoing amyloidogenesis. Subsequent immunohistochemical analysis of the same brain regions showed increased microglial and astrocytic immunoreactivity associated with the amyloid deposits, as expected from previous studies, but did not reveal any particular astrocytic or microglial feature correlated with cholesterol granulation. However, dystrophic neurites as well as presynaptic vesicles presented a distribution similar to that of cholesterol granules in regions undergoing amyloid-beta accumulation, thus indicating that these neuronal endpoints may retain cholesterol in areas with lesions. In conclusion, the present study provides evidence for an altered cholesterol distribution near amyloid deposits that would have been missed by several other lipid analysis methods, and opens for the possibility to study in detail the putative liaison between lipid environment and protein structure and function in Alzheimer's disease.
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| 2. |
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| 3. |
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| 4. |
- Lang, Jenny, et al.
(författare)
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Reliability study of a RF power amplifier with GaN-on-SiC HEMTs
- 2016
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Ingår i: ECS Transactions. - Pennington, N.J. : The Electrochemical Society. - 9781607685395 ; , s. 49-59
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Konferensbidrag (refereegranskat)abstract
- RF power amplifier demonstrators containing each one GaN-on- SiC, HEMT, CHZ015A-QEG, from UMS in SMD quad-flat noleads package (QFN) were subjected to thermal cycles (TC) and power cycles (PC) and evaluated electrically, thermally and structurally. Two types of lead-free solders (Sn63Pb36Ag2 and SnAgCu (SAC305)) and two types of TIM materials (NanoTIM and TgonTM 805) for PCB attachment to liquid cold plate were tested for thermo-mechanical reliability. Changes in electrical performance of the devices namely reduction of the current saturation value, threshold voltage shift, increase of the leakage current and degradation of the HF performance were observed as a result of an accumulated current stress during PC. No significant changes in the investigated solder or TIM materials were observed.
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| 5. |
- Lang, Jenny, et al.
(författare)
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Reliability Study of GaN-onSiC HEMT RF Power Amplifiers
- 2018
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Ingår i: Advances in Technology Innovation. ; 3:4, s. 157-165
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Tidskriftsartikel (refereegranskat)abstract
- The RF power amplifier demonstrators containing each one GaN-on-SiC, HEMT, CHZ015A-QEG, from UMSin SMD quad-flat no-leads package (QFN) were subjected to thermal cycles (TC) and power cycles (PC) andevaluated electrically, thermally and structurally. Two types of solders, Sn63Pb36Ag2 and lead-free SnAgCu(SAC305), and two types of TIM materials, NanoTIM and TgonTM 805, for PCB attachment to the liquid cold platewere tested for thermo-mechanical reliability. Changes in the electrical performance of the devices, namely thereduction of the current saturation value, threshold voltage shift, increase of the leakage current and degradation ofthe HF performance were observed as a result of an accumulated current stress during PC. No significant changes inthe investigated solder or TIM materials were observed.
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| 6. |
- Lang, Jenny, et al.
(författare)
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Thermo-mechanical reliability and performance degradation of a lead-free RF power amplifier with GaN-on-SiC HEMTs
- 2017
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Ingår i: Materials Science Forum. - : Trans Tech Publications. - 9783035710434 ; , s. 715-718
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Konferensbidrag (refereegranskat)abstract
- RF power amplifier demonstrators containing each one GaN-on-SiC, HEMT, CHZ015AQEG, from UMS in SMD quad-flat no-leads package (QFN) were subjected to thermal cycles (TC) and power cycles (PC) followed by electrical, thermal and structural evaluation. Two types of solders i.e. Sn63Pb36Ag2 and lead-free SnAgCu (SAC305) and two types of TIM materials (NanoTIM and TgonTM 805) for PCB attachment to liquid cold plate were tested for thermomechanical reliability. Changes in electrical performance of the devices namely reduction of the current saturation value, threshold voltage shift, increase of the leakage current and degradation of the HF performance were observed as a result of an accumulated current stress during PC. No significant changes in the investigated solder or TIM materials were observed.
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| 7. |
- Mitraka, Evangelia, et al.
(författare)
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Solution processed liquid metal-conducting polymer hybrid thin films as electrochemical pH-threshold indicators
- 2015
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Ingår i: Journal of Materials Chemistry C. - : Royal Society of Chemistry. - 2050-7526 .- 2050-7534. ; 3:29, s. 7604-7611
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Tidskriftsartikel (refereegranskat)abstract
- A global and accurate mapping of the environment could be achieved if sensors and indicators are mass-produced at low cost. Printed electronics using polymeric (semi) conductors offer a platform for such sensor/indicator based circuits. Herein, we present the material concept for an electrochemical pH-threshold indicator based on a printable hybrid electrode which comprises a liquid metal alloy (GaInSn) embedded in a conducting polymer matrix (PEDOT). This hybrid electrode displays a large variation in open circuit potential versus pH in an electrochemical cell, which when connected to the gate of an electrochemical transistor leads to a dramatic change in the drain current in a narrow range of pH.
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| 8. |
- Persson, Kristin M, et al.
(författare)
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Electronic control over detachment of a self-doped water-soluble conjugated polyelectrolyte
- 2014
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Ingår i: Langmuir. - : American Chemical Society. - 0743-7463 .- 1520-5827. ; 30:21, s. 6257-6266
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Tidskriftsartikel (refereegranskat)abstract
- Water-soluble conducting polymers are of interest to enable more versatile processing in aqueous media as well as to facilitate interactions with biomolecules. Here, we report a substituted poly(3,4-ethylenedioxythiophene) derivative (PEDOT-S:H) that is fully water-soluble and self-doped. When electrochemically oxidizing a PEDOT-S:H thin film, the film detaches from the underlying electrode. The oxidation of PEDOT-S:H starts with an initial phase of swelling followed by cracking before it finally disrupts into small flakes and detaches from the electrode. We investigated the detachment mechanism and found that parameters such as the size, charge, and concentration of ions in the electrolyte, the temperature, and also the pH influence the characteristics of detachment. When oxidizing PEDOT-S:H, the positively charged polymer backbone is balanced by anions from the electrolyte solution and also by the sulfonate groups on the side chains (more self-doping). From our experiments, we conclude that detachment of the PEDOT-S:H film upon oxidation occurs in part due to swelling caused by an inflow of solvated anions and associated water and in part due to chain rearrangements within the film, caused by more self-doping. We believe that PEDOT-S:H detachment can be of interest in a number of different applications, including addressed and active control of the release of materials such as biomolecules and cell cultures. © 2014 American Chemical Society.
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