| 1. |
- Adolf, A., et al.
(författare)
-
Release of astroglial vimentin by extracellular vesicles: Modulation of binding and internalization of C3 transferase in astrocytes and neurons
- 2019
-
Ingår i: Glia. - : Wiley. - 0894-1491. ; 67:4, s. 703-717
-
Tidskriftsartikel (refereegranskat)abstract
- Clostridium botulinum C3 transferase (C3bot) ADP-ribosylates rho proteins to change cellular functions in a variety of cell types including astrocytes and neurons. The intermediate filament protein vimentin as well as transmembrane integrins are involved in internalization of C3bot into cells. The exact contribution, however, of these proteins to binding of C3bot to the cell surface and subsequent cellular uptake remains to be unraveled. By comparing primary astrocyte cultures derived from wild-type with Vim(-/-) mice, we demonstrate that astrocytes lacking vimentin exhibited a delayed ADP-ribosylation of rhoA concurrent with a blunted morphological response. This functional impairment was rescued by the extracellular excess of recombinant vimentin. Binding assays using C3bot harboring a mutated integrin-binding RGD motif (C3bot-G89I) revealed the involvement of integrins in astrocyte binding of C3bot. Axonotrophic effects of C3bot are vimentin dependent and postulate an underlying mechanism entertaining a molecular cross-talk between astrocytes and neurons. We present functional evidence for astrocytic release of vimentin by exosomes using an in vitro scratch wound model. Exosomal vimentin+ particles released from wild-type astrocytes promote the interaction of C3bot with neuronal membranes. This effect vanished when culturing Vim(-/-) astrocytes. Specificity of these findings was confirmed by recombinant vimentin propagating enhanced binding of C3bot to synaptosomes from rat spinal cord and mouse brain. We hypothesize that vimentin+ exosomes released by reactive astrocytes provide a novel molecular mechanism constituting axonotrophic (neuroprotective) and plasticity augmenting effects of C3bot after spinal cord injury.
|
|
| 2. |
- Bakowski, Mietek, et al.
(författare)
-
Design and characterization of newly developed 10 kV 2 A SiC p-i-n diode for soft-switching industrial power supply
- 2015
-
Ingår i: IEEE Transactions on Electron Devices. - : Institute of Electrical and Electronics Engineers Inc.. - 0018-9383 .- 1557-9646. ; 62:2, s. 366-373
-
Tidskriftsartikel (refereegranskat)abstract
- 10 kV, 2 A SiC p-i-n diodes have been designed and fabricated. The devices feature excellent stability of forward characteristics and robust junction termination with avalanche capability of 1 J. The fabricated diodes have been electrically evaluated with respect to dynamic ON-state voltage, reverse recovery behavior, bipolar stability, and avalanche capability. More than 60% reduction of losses has been demonstrated using newly developed 10-kV p-i-n diodes in a multikilowatt high voltage, high-frequency dc/dc soft-switching converter
|
|
| 3. |
- Gil-Romera, Graciela, et al.
(författare)
-
Long-term fire resilience of the Ericaceous Belt, Bale Mountains, Ethiopia
- 2019
-
Ingår i: Biology Letters. - : The Royal Society. - 1744-9561 .- 1744-957X. ; 15:7
-
Tidskriftsartikel (refereegranskat)abstract
- Fire is the most frequent disturbance in the Ericaceous Belt (ca 3000-1300 m.a.s.l.), one of the most important plant communities of tropical African mountains. Through resprouting after fire, Erica establishes a positive fire feedback under certain burning regimes. However, present-day human activity in the Bale Mountains of Ethiopia includes fire and grating systems that may have a negative impact on the resilience of the ericaceous ecosystem. Current knowledge of Erica-fire relationships is based on studies of modern vegetation, lacking a longer time perspective that can shed light on baseline conditions for the fire feedback. We hypothesite that fire has influenced Erica communities in the Bale Mountains at millennial time-scales. To test this, we (1) identity the tire history ot the Bale Mountains through a pollen and charcoal record from Garba Guracha, a lake at 3950 m.a.s.l., and (2) describe the long-term bidirectional feedback between wildfire and Erica, which may control the ecosystem's resilience. Our results support fire occurrence in the area since ca 14 000 years ago, with particularly intense burning during the early Holocene, 10.8-6.0 cal ka BP. We show that a positive feedback between Erica abundance and fire occurrence was in operation throughout the Lateglacial and Holocene, and interpret the Ericaceous Bolt of the Ethiopian mountains as a long-term fire resilient ecosystem. We propose that controlled burning should be an integral part of landscape management in the Bale Mountains National Park.
|
|
| 4. |
- Mikhaylov, Aleksey I., et al.
(författare)
-
Effect of phosphorus implantation prior to oxidation on electrical properties of thermally grown SiO2/4H-SiC MOS structures
- 2015
-
Ingår i: Mater. Sci. Forum. - : Trans Tech Publications Ltd. - 9783038352945 ; , s. 133-138
-
Konferensbidrag (refereegranskat)abstract
- The electrical properties of metal-oxide-semiconductor (MOS) devices fabricated using dry oxidation on phosphorus-implanted n-type 4H-SiC (0001) epilayers have been investigated. MOS structures were compared in terms of interface traps and reliability with reference sample which was produced by dry oxidation under the same conditions. The notably lower interface traps density measured in MOS capacitor with phosphorus concentration exceeding 1018 cm-3 at the SiO2/SiC interface was attributed to interface traps passivation by incorporated phosphorus ions. © (2015) Trans Tech Publications, Switzerland.
|
|
| 5. |
- Schöner, Adolf, et al.
(författare)
-
Progress in buried grid technology for improvements in on-resistance of high voltage SiC devices
- 2016
-
Ingår i: ECS Transactions. - : The Electrochemical Society. - 9781607685395 ; , s. 183-190
-
Konferensbidrag (refereegranskat)abstract
- Buried grid technology is suggested to protect field sensitive device areas from high electric field in order to improve the high temperature and high voltage performance of SiC devices. More than three orders of magnitude lower leakage currents have been demonstrated at high temperature operation. The drawback is that the total resistance increases due to the introduction of the buried grid leading to higher voltage drop at rated current and higher conduction losses. In this paper, we discuss doping and barrier engineering methods in order to take full advantage of the superior shielding effect of the buried grid technology and at the same time minimize the effect on the current conduction. As example, the design considerations for a 1200 V SiC buried grid JBS diode in terms of epi structure doping as well as buried grid properties is comprehensively investigated to optimize the on-state condition.
|
|
| 6. |
- Zhang, Andy Zhenzhong, et al.
(författare)
-
Planarization of epitaxial SiC trench structures by plasma ion etching
- 2015
-
Ingår i: Materials Science Forum. - 0255-5476 .- 1662-9752. - 9783038354789 ; 821-823, s. 549-552
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, we present a planarization concept for epitaxial SiC trench structures involving reactive ion etching (RIE) and inductive coupled plasma (ICP) dry etching. The general idea is to transfer the flat surface from spun-on BCB/photo-resist layers to deposited silicon dioxide and finally to bulk SiC by applying process conditions with the same etch rate for the different materials. In this way several microns of unwanted material can be removed and planar SiC surfaces are obtained. With this method trench structures filled by epitaxial re-growth can be planarized with smooth surfaces and good homogeneity over the wafer. Cost-efficient device manufacturing can be achieved by using standard semiconductor process equipment. This technology makes it possible to manufacture advanced epitaxial SiC material structures for devices such as trench JBS diodes and double-gate trench JFETs.
|
|
