| 1. |
|
|
| 2. |
|
|
| 3. |
- Chelban, V., et al.
(författare)
-
PDXK mutations cause polyneuropathy responsive to pyridoxal 5′-phosphate supplementation
- 2019
-
Ingår i: Annals of Neurology. - : Wiley. - 0364-5134 .- 1531-8249. ; 86:2, s. 225-240
-
Tidskriftsartikel (refereegranskat)abstract
- Objective: To identify disease-causing variants in autosomal recessive axonal polyneuropathy with optic atrophy and provide targeted replacement therapy. Methods: We performed genome-wide sequencing, homozygosity mapping, and segregation analysis for novel disease-causing gene discovery. We used circular dichroism to show secondary structure changes and isothermal titration calorimetry to investigate the impact of variants on adenosine triphosphate (ATP) binding. Pathogenicity was further supported by enzymatic assays and mass spectroscopy on recombinant protein, patient-derived fibroblasts, plasma, and erythrocytes. Response to supplementation was measured with clinical validated rating scales, electrophysiology, and biochemical quantification. Results: We identified biallelic mutations in PDXK in 5 individuals from 2 unrelated families with primary axonal polyneuropathy and optic atrophy. The natural history of this disorder suggests that untreated, affected individuals become wheelchair-bound and blind. We identified conformational rearrangement in the mutant enzyme around the ATP-binding pocket. Low PDXK ATP binding resulted in decreased erythrocyte PDXK activity and low pyridoxal 5′-phosphate (PLP) concentrations. We rescued the clinical and biochemical profile with PLP supplementation in 1 family, improvement in power, pain, and fatigue contributing to patients regaining their ability to walk independently during the first year of PLP normalization. Interpretation: We show that mutations in PDXK cause autosomal recessive axonal peripheral polyneuropathy leading to disease via reduced PDXK enzymatic activity and low PLP. We show that the biochemical profile can be rescued with PLP supplementation associated with clinical improvement. As B6 is a cofactor in diverse essential biological pathways, our findings may have direct implications for neuropathies of unknown etiology characterized by reduced PLP levels. ANN NEUROL 2019;86:225–240. © 2019 The Authors. Annals of Neurology published by Wiley Periodicals, Inc. on behalf of American Neurological Association.
|
|
| 4. |
|
|
| 5. |
- Daniau, A. -L, et al.
(författare)
-
predictability of biomass burning in response to climate changes
- 2012
-
Ingår i: Global Biogeochemical Cycles. - 0886-6236 .- 1944-9224. ; 26, s. GB4007-
-
Tidskriftsartikel (refereegranskat)abstract
- Climate is an important control on biomass burning, but the sensitivity of fire to changes in temperature and moisture balance has not been quantified. We analyze sedimentary charcoal records to show that the changes in fire regime over the past 21,000 yrs are predictable from changes in regional climates. Analyses of paleo-fire data show that fire increases monotonically with changes in temperature and peaks at intermediate moisture levels, and that temperature is quantitatively the most important driver of changes in biomass burning over the past 21,000 yrs. Given that a similar relationship between climate drivers and fire emerges from analyses of the interannual variability in biomass burning shown by remote-sensing observations of month-by-month burnt area between 1996 and 2008, our results signal a serious cause for concern in the face of continuing global warming.
|
|
| 6. |
|
|
| 7. |
- Bagdonaite, Ieva, et al.
(författare)
-
Glycoengineered keratinocyte library reveals essential functions of specific glycans for all stages of HSV-1 infection
- 2023
-
Ingår i: Nature Communications. - 2041-1723. ; 14:1
-
Tidskriftsartikel (refereegranskat)abstract
- Viral and host glycans represent an understudied aspect of host-pathogen interactions, despite potential implications for treatment of viral infections. This is due to lack of easily accessible tools for analyzing glycan function in a meaningful context. Here we generate a glycoengineered keratinocyte library delineating human glycosylation pathways to uncover roles of specific glycans at different stages of herpes simplex virus type 1 (HSV-1) infectious cycle. We show the importance of cellular glycosaminoglycans and glycosphingolipids for HSV-1 attachment, N-glycans for entry and spread, and O-glycans for propagation. While altered virion surface structures have minimal effects on the early interactions with wild type cells, mutation of specific O-glycosylation sites affects glycoprotein surface expression and function. In conclusion, the data demonstrates the importance of specific glycans in a clinically relevant human model of HSV-1 infection and highlights the utility of genetic engineering to elucidate the roles of specific viral and cellular carbohydrate structures.
|
|
| 8. |
- Lorenzzi, J., et al.
(författare)
-
Incorporation of group III, IV and V elements in 3C–SiC(1 1 1) layers grown by the vapour–liquid–solid mechanism
- 2010
-
Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248 .- 1873-5002. ; 312:23, s. 3443-3450
-
Tidskriftsartikel (refereegranskat)abstract
- We report on a comparative investigation of the incorporation of group III, IV and V impurities in 3C–SiC heteroepitaxial layers grown by the vapour–liquid–solid (VLS) mechanism on on-axis α-SiC substrates. To this end, various Si-based melts have been used with addition of Al, Ga, Ge and Sn species. Homoepitaxial α-SiC layers grown using Al-based melts were used for comparison purposed for Al incorporation. Nitrogen incorporation depth profile systematically displays an overshoot at the substrate/epilayer interface for all the layers. Ga and Al incorporations follow the same distribution shape as N whereas this is not the case for the isoelectronic impurities Ge and Sn. This suggests some interaction between Ga/Al and N coming from the high bonding energy between the group III and V elements, which does not exist with Ge and Sn. This is why both incorporate as a cluster. A model of incorporation is proposed taking into account metal-N and metal-C bonding energies together with the solid solubility of the corresponding nitrides.
|
|
| 9. |
- Sendova-Vassileva, M, et al.
(författare)
-
Depth dependence of photoluminescence and chemical bonding in porous silicon
- 1999
-
Ingår i: Journal of Luminescence. - 0022-2313 .- 1872-7883. ; 80:1-4, s. 179-182
-
Tidskriftsartikel (refereegranskat)abstract
- Porous silicon (PS) is studied by stepwise peeling of the surface layer to clarify the non-uniformity in the photoluminescence (PL) and correlate it with the in-depth chemical bonding and structure of the 30 μm thick layer. The PL intensity grows by an order of magnitude after the peeling off of the first 10 μm and decreases five times in the next 5 μm while the peak maximum position shifts from 730 to 800 nm. X-ray photoelectron spectroscopy (XPS) measurements show that Si–Si and Si–O bonds are present both on the surface and below, and the preferential oxidation state of silicon changes from 3+ and 4+ on the surface to 1+ and 2+ below 10 μm. Using Raman spectroscopy silicon nanocrystals are shown to exist. Their mean size can be estimated at about 3 nm. These results show that the strongest PL comes from a region in the PS layer where silicon nanocrystallites are surrounded by oxides with a low level of oxidation and not from the strongly oxidized surface layer.
|
|
| 10. |
- Singh, I N, et al.
(författare)
-
Dynorphin A (1-17) induces apoptosis in striatal neurons in vitro through alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate/kainate receptor-mediated cytochrome c release and caspase-3 activation.
- 2003
-
Ingår i: Neuroscience. - : Elsevier BV. - 0306-4522 .- 1873-7544. ; 122:4
-
Tidskriftsartikel (refereegranskat)abstract
- Dynorphin A (1-17), an endogenous opioid neuropeptide, can have pathophysiological consequences at high concentrations through actions involving glutamate receptors. Despite evidence of excitotoxicity, the basic mechanisms underlying dynorphin-induced cell death have not been explored. To address this question, we examined the role of caspase-dependent apoptotic events in mediating dynorphin A (1-17) toxicity in embryonic mouse striatal neuron cultures. In addition, the role of opioid and/or glutamate receptors were assessed pharmacologically using dizocilpine maleate (MK(+)801), a non-equilibrium N-methyl-D-aspartate (NMDA) antagonist; 6-cyano-7-nitroquinoxaline-2,3-dione, a competitive alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA)/kainate antagonist; or (-)-naloxone, a general opioid antagonist. The results show that dynorphin A (1-17) (>or=10 nM) caused concentration-dependent increases in caspase-3 activity that were accompanied by mitochondrial release of cytochrome c and the subsequent death of cultured mouse striatal neurons. Moreover, dynorphin A-induced neurotoxicity and caspase-3 activation were significantly attenuated by the cell permeable caspase inhibitor, caspase-3 inhibitor-II (z-DEVD-FMK), further suggesting an apoptotic cascade involving caspase-3. AMPA/kainate receptor blockade significantly attenuated dynorphin A-induced cytochrome c release and/or caspase-3 activity, while NMDA or opioid receptor blockade typically failed to prevent the apoptotic response. Last, dynorphin-induced caspase-3 activation was mimicked by the ampakine CX546 [1-(1,4-benzodioxan-6-ylcarbonyl)piperidine], which suggests that the activation of AMPA receptor subunits may be sufficient to mediate toxicity in striatal neurons. These findings provide novel evidence that dynorphin-induced striatal neurotoxicity is mediated by a caspase-dependent apoptotic mechanism that largely involves AMPA/kainate receptors.
|
|
| 11. |
- Abraham, Vojtech, et al.
(författare)
-
Patterns in recent and Holocene pollen accumulation rates across Europe - the Pollen Monitoring Programme Database as a tool for vegetation reconstruction
- 2021
-
Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 18:15, s. 4511-4534
-
Tidskriftsartikel (refereegranskat)abstract
- The collection of modern, spatially extensive pollen data is important for the interpretation of fossil pollen assemblages and the reconstruction of past vegetation communities in space and time. Modern datasets are readily available for percentage data but lacking for pollen accumulation rates (PARs). Filling this gap has been the motivation of the pollen monitoring network, whose contributors monitored pollen deposition in modified Tauber traps for several years or decades across Europe. Here we present this monitoring dataset consisting of 351 trap locations with a total of 2742 annual samples covering the period from 1981 to 2017. This dataset shows that total PAR is influenced by forest cover and climate parameters, which determine pollen productivity and correlate with latitude. Treeless vegetation produced PAR values of at least 140 grains cm(-2) yr(-1). Tree PAR increased by at least 400 grains cm(-2) yr(-1) with each 10% increase in forest cover. Pollen traps situated beyond 200 km of the distribution of a given tree species still collect occasional pollen grains of that species. The threshold of this long-distance transport differs for individual species and is generally below 60 grains cm(-2) yr(-1). Comparisons between modern and fossil PAR from the same regions show similar values. For temperate taxa, modern analogues for fossil PARs are generally found downslope or southward of the fossil sites. While we do not find modern situations comparable to fossil PAR values of some taxa (e.g. Corylus), CO2 fertilization and land use may cause high modern PARs that are not documented in the fossil record. The modern data are now publicly available in the Neotoma Paleoecology Database and aid interpretations of fossil PAR data.
|
|
| 12. |
- Feurdean, Angelica, et al.
(författare)
-
Origin of the forest steppe and exceptional grassland diversity in Transylvania (central-eastern Europe)
- 2015
-
Ingår i: Journal of Biogeography. - : Wiley. - 1365-2699 .- 0305-0270. ; 42:5, s. 951-963
-
Tidskriftsartikel (refereegranskat)abstract
- Aim The forest steppe of the Transylvanian Plain is a landscape of exceptionally diverse steppe-like and semi-natural grasslands. Is this vegetation a remnant of a once continuous temperate forest extensively cleared by humans, or has the area, since the last glacial, always been a forest steppe? Understanding the processes that drive temperate grassland formation is important because effective management of this biome is critical to the conservation of the European cultural landscape. Location Lake Stiucii, north-western Romania, central-eastern Europe. Methods We analysed multi-proxy variables (pollen, coprophilous fungi, plant macroremains, macrocharcoal) from a 55,000year discontinuous sequence (c. 55,000-35,000; 13,000-0cal. yr bp), integrating models of pollen-based vegetation cover, biome reconstruction, global atmospheric simulations and archaeological records. Results Needleleaf woodland occurred during glacial Marine Isotope Stage (MIS) 3, but contracted at the end of this period. Forest coverage of c. 55% (early Holocene) and 65% (mid-Holocene) prevailed through the Holocene, but Bronze Age humans extensively cleared forests after 3700cal. yr bp. Forest coverage was most widespread between 8600 and 3700cal. yr bp, whereas grasses, steppe and xerothermic forbs were most extensive between 11,700 and 8600cal. yr bp and during the last 3700cal. yr bp. Cerealia pollen indicate the presence of arable agriculture by c. 7000cal. yr bp. Main conclusions We have provided the first unequivocal evidence for needleleaf woodland during glacial MIS 3 in this region. Extensive forests prevailed prior to 3700cal. yr bp, challenging the hypothesis that the Transylvanian lowlands were never wooded following the last glaciation. However, these forests were never fully closed either, reflecting dry growing season conditions, recurrent fires and anthropogenic impacts, which have favoured grassland persistence throughout the Holocene. The longevity of natural and semi-natural grasslands in the region may explain their current exceptional biodiversity. This longer-term perspective implies that future climatic warming and associated fire will maintain these grasslands.
|
|
| 13. |
|
|
| 14. |
- Marinova, Ts., et al.
(författare)
-
Nickel based ohmic contacts on SiC
- 1997
-
Ingår i: Materials Science and Engineering B. - 0921-5107. ; 46:1-3, s. 223-226
-
Tidskriftsartikel (refereegranskat)abstract
- We have compared the chemical and structural properties of Ni/SiC and Ni2Si/SiC interfaces. In the case of Ni/SiC, the contact formation is initiated by the dissociation of SiC, due to the strong reactivity of nickel at 950 °C. Ni2Si is formed and carbon accumulates, both at the interface and throughout the metal layer. At the interface, many Kirkendall voids are observed by TEM. Despite this poor interface morphology, low contact resistances have been measured. But the presence of carbon in the contact layer and at the interface is a potential source of contact degradation at high temperature. In the case of Ni/Si multilayers evaporated on SiC instead of pure Ni, the contact formation is preceded by Ni and Si mutual diffusion in the deposited layer yielding Ni2Si. Therefore, a smaller amount of carbon is released from SiC. Low carbon segregation, abrupt interface and low contact resistance characterize this contact. The thermal stability of Ni2Si contacts is illustrated with ageing experiments carried out at 500 °C.
|
|
| 15. |
- Marinova, Ts., et al.
(författare)
-
XPS depth profiling of laser-annealed Zn+-implanted GaAs
- 1997
-
Ingår i: Applied Surface Science. - 0169-4332 .- 1873-5584. ; 109/110, s. 80-86
-
Tidskriftsartikel (refereegranskat)abstract
- Data on the effects of 140 keV Zn+-implantation in (100) GaAs and the consequent low power pulsed laser annealing (LPPLA) on the As/Ga ratio and the chemical states of the elements at the surface and in the subsurface region are presented. The results include the depth distribution of the elements for virgin, as-implanted and implanted+LPPLA [30×(4.5/7.5) MW/cm2] samples. The X-ray photoelectron spectra of as-implanted samples show that a low-intensity Zn 2p peak is observed after 20 min of Ar+ sputtering with an energy of 3 keV, corresponding to about 20 nm of etched material. The depth profiling XPS analysis confirms the ‘recovering' of the stoichiometry of Zn+-implanted specimens after LPPLA with laser pulses of a power density in the energy window of (5–7 MW/cm2). At laser pulse power densities outside of this energy window (4.5 and 7.5 MW/cm2) Zn appears again in the XP spectra after 20 min sputtering as in the case of as-implanted GaAs.
|
|
| 16. |
- Marinova, Zoya, et al.
(författare)
-
Translocation of dynorphin neuropeptides across the plasma membrane. A putative mechanism of signal transmission.
- 2005
-
Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 280:28
-
Tidskriftsartikel (refereegranskat)abstract
- Several peptides, including penetratin and Tat, are known to translocate across the plasma membrane. Dynorphin opioid peptides are similar to cell-penetrating peptides in a high content of basic and hydrophobic amino acid residues. We demonstrate that dynorphin A and big dynorphin, consisting of dynorphins A and B, can penetrate into neurons and non-neuronal cells using confocal fluorescence microscopy/immunolabeling. The peptide distribution was characterized by cytoplasmic labeling with minimal signal in the cell nucleus and on the plasma membrane. Translocated peptides were associated with the endoplasmic reticulum but not with the Golgi apparatus or clathrin-coated endocytotic vesicles. Rapid entry of dynorphin A into the cytoplasm of live cells was revealed by fluorescence correlation spectroscopy. The translocation potential of dynorphin A was comparable with that of transportan-10, a prototypical cell-penetrating peptide. A central big dynorphin fragment, which retains all basic amino acids, and dynorphin B did not enter the cells. The latter two peptides interacted with negatively charged phospholipid vesicles similarly to big dynorphin and dynorphin A, suggesting that interactions of these peptides with phospholipids in the plasma membrane are not impaired. Translocation was not mediated via opioid receptors. The potential of dynorphins to penetrate into cells correlates with their ability to induce non-opioid effects in animals. Translocation across the plasma membrane may represent a previously unknown mechanism by which dynorphins can signal information to the cell interior.
|
|
| 17. |
- Robert, T., et al.
(författare)
-
6H-type zigzag faults in low-doped 4H-SiC epitaxial layers.
- 2010
-
Ingår i: Mat. Sci. Forum, Vols. 645-648. - 0878492798 - 9780878492794 ; , s. 347-350
-
Konferensbidrag (refereegranskat)abstract
- A new type of 6H zigzag faults has been identified from high resolution transmission electron microscopy (HRTEM) measurements performed on low-doped 4H-SiC homoepitaxial layer grown on off-axis substrates in a hot-wall CVD reactor. They are made of half unit cells of 6H with corresponding low temperature photoluminescence (LTPL) response ranging from about 3 eV to 2.5 eV at liquid helium temperature.
|
|
| 18. |
- Sim, Thomas G., et al.
(författare)
-
Regional variability in peatland burning at mid-to high-latitudes during the Holocene
- 2023
-
Ingår i: Quaternary Science Reviews. - : Elsevier. - 0277-3791 .- 1873-457X. ; 305
-
Tidskriftsartikel (refereegranskat)abstract
- Northern peatlands store globally-important amounts of carbon in the form of partly decomposed plant detritus. Drying associated with climate and land-use change may lead to increased fire frequency and severity in peatlands and the rapid loss of carbon to the atmosphere. However, our understanding of the patterns and drivers of peatland burning on an appropriate decadal to millennial timescale relies heavily on individual site-based reconstructions. For the first time, we synthesise peatland macrocharcoal re-cords from across North America, Europe, and Patagonia to reveal regional variation in peatland burning during the Holocene. We used an existing database of proximal sedimentary charcoal to represent regional burning trends in the wider landscape for each region. Long-term trends in peatland burning appear to be largely climate driven, with human activities likely having an increasing influence in the late Holocene. Warmer conditions during the Holocene Thermal Maximum (similar to 9e6 cal. ka BP) were associated with greater peatland burning in North America's Atlantic coast, southern Scandinavia and the Baltics, and Patagonia. Since the Little Ice Age, peatland burning has declined across North America and in some areas of Europe. This decline is mirrored by a decrease in wider landscape burning in some, but not all sub-regions, linked to fire-suppression policies, and landscape fragmentation caused by agricultural expansion. Peatlands demonstrate lower susceptibility to burning than the wider landscape in several instances, probably because of autogenic processes that maintain high levels of near-surface wetness even during drought. Nonetheless, widespread drying and degradation of peatlands, particularly in Europe, has likely increased their vulnerability to burning in recent centuries. Consequently, peatland restoration efforts are important to mitigate the risk of peatland fire under a changing climate. Finally, we make recommendations for future research to improve our understanding of the controls on peatland fires.(c) 2023 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
|
|
| 19. |
|
|
| 20. |
|
|
| 21. |
- Tress, Wolfgang, et al.
(författare)
-
The role of the hole-transport layer in perovskite solar cells - reducing recombination and increasing absorption
- 2014
-
Ingår i: 2014 IEEE 40TH PHOTOVOLTAIC SPECIALIST CONFERENCE (PVSC). - : IEEE. - 9781479943982 ; , s. 1563-1566
-
Konferensbidrag (refereegranskat)abstract
- The role of the hole-transport layer (HTL) in CH3NH3PbI3 perovskite solar cells is investigated. It is found that it mainly serves three purposes: First, deposited prior to the gold electrode, it avoids direct contact of the metal electrode with the meso porous TiO2-perovskite layer, and therefore increases the selectivity of the contact. This reduces recombination as evident from an increased open-circuit voltage and a higher luminescence efficiency. Second, the HTL increases the internal quantum efficiency independent of applied voltage and illumination wavelength by reducing (diffusion) losses of charges. Third, due to a smoothing of the TiO2-perovskite mesoscopic layer the HTL increases the reflectivity of the gold electrode, allowing for a second path of the light through the absorber. Both effects result in an enhancement of the short-circuit current density.
|
|
| 22. |
- Vasiliauskas, Remigijus, et al.
(författare)
-
Effect of initial substrate conditions on growth of cubic silicon carbide
- 2011
-
Ingår i: Journal of Crystal Growth. - : Elsevier Science B.V., Amsterdam.. - 0022-0248 .- 1873-5002. ; 324:1, s. 7-14
-
Tidskriftsartikel (refereegranskat)abstract
- In order to analyze the epitaxial growth of cubic silicon carbide by sublimation epitaxy on different substrates, four different 6H-SiC substrate preparations were used: (i) as-received, (ii) re-polished, (iii) annealed and covered by silicon layer and (iv) with (1 1 1) 3C-SiC buffer layer. Almost 100% coverage and low twin density was achieved when grown on the buffer layer. The XRD and TEM characterizations show better material quality when the layer is grown directly on 6H-SiC substrates. Background doping evaluated by LTPL is in the range of 10(16) cm(-3) for N and 10(16) cm(-3) for Al in all grown layers.
|
|
| 23. |
- Vasiliauskas, Remigijus, et al.
(författare)
-
Polytype transformation and structural characteristics of 3C-SiC on 6H-SiC substrates
- 2014
-
Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248 .- 1873-5002. ; 395, s. 109-115
-
Tidskriftsartikel (refereegranskat)abstract
- The 3C-SiC (111) was grown on on-axis 6H-SiC substrates in a temperature interval ranging from 1675oC where 3C-SiC nucleated, to 1825oC where coverage of the substrate by 3C-SiC was nearly 100%. The 6H- to 3C-SiC transformation was not abrupt and two different transitions could be observed. The first one occurs before or during 3C-SiC nucleation and consists of 6H-, 3C-, 15R-SiC and other unresolved stacking sequences. The second one appears due to 6H-SiC and 3C-SiC competition during the growth and results in non flat needle-like interface. A proposed model elucidates connection between four-fold twins nucleating at the 6H-/3C-SiC interface and the formation of depressions at the surface of the 3C-SiC layer.
|
|
| 24. |
- Vasiliauskas, Remigijus, et al.
(författare)
-
Sublimation Growth and Structural Characterization of 3C-SiC on Hexagonal and Cubic SiC Seeds
- 2010
-
Ingår i: Materials Science Forum, Vols. 645-648. - : Transtec Publications; 1999. ; , s. 175-178
-
Konferensbidrag (refereegranskat)abstract
- Epitaxial growth of cubic silicon carbide on 6H-SiC substrates, and 6H-SiC substrates with (111) 3C-SiC buffer layer, deposited by vapour liquid solid mechanism, was compared. The morphological details of the grown layers were studied by optical microscopy and their microstructure by transmission electron microscopy. The influence of the substrate on the nucleation of 3C-SiC, the initial homoepitaxial 6H-SiC nucleation before 3C-SiC as well as the formation of defects, are discussed.
|
|
| 25. |
|
|
