1,147 research outputs found
Optimization of Material Contrast for Efficient FIBâSEM Tomography of Solid Oxide Fuel Cells
Focused ion beam (FIB) â scanning electron microscopy (SEM) serial sectioning tomography has become an important tool for threeâdimensional microstructure reconstruction of solid oxide fuel cells (SOFC) to obtain an understanding of fabricationârelated effects and SOFC performance. By sequential FIB milling and SEM imaging a stack of crossâsection images across all functional SOFC layers was generated covering a large volume of 3.5·10 ÎŒm. One crucial step is image segmentation where regions with different image intensities are assigned to different material phases within the SOFC. To analyze all relevant SOFC materials, it was up to now mandatory to acquire several images by scanning the same region with different imaging parameters because sufficient material contrast could otherwise not be achieved. In this work we obtained highâcontast SEM images from a single scan to reconstract all functional SOFC layers consisting of a Ni/YOâdoped ZrO (YDZ) cermet anode, YDZ electrolyte and (La,Sr)MnO/YDZ cathode. This was possible by using different, simultaneous readâout detectors installed in a stateâofâtheâart scanning electron microscope. In addition, we used a deterministic approach for the optimization of imaging parameters by employing Monte Carlo simulations rather than trialâandâerror tests. We also studied the effect of detection geometry, detecting angle range and detector type
Glass-formingproperty of hydroxyectoine is the cause of its superior function as a desiccation protectant
We were able to demonstrate that hydroxyectoine, in contrast to ectoine, is a good glass-forming compound. Fourier transform infrared and spin label electron spin resonance studies of dry ectoine and hydroxyectoine have shown that the superior glass-forming properties of hydroxyectoine result from stronger intermolecular H-bonds with the OH group of hydroxyectoine. Spin probe experiments have also shown that better molecular immobilization in dry hydroxyectoine provides better redox stability of the molecules embedded in this dry matrix. With a glass transition temperature of 87°C (vs. 47°C for ectoine) hydroxyectoine displays remarkable desiccation protection properties, on a par with sucrose and trehalose. This explains its accumulation in response to increased salinity and elevated temperature by halophiles such as Halomonas elongata and its successful application in âanhydrobiotic engineeringâ of both enzymes and whole cells
A theoretical insight into the photophysics of psoralen
Psoralen photophysics has been studied on quantum chemistry grounds using the multiconfigurational second-order perturbation method CASPT2. Absorption and emission spectra of the system have been rationalized by computing the energies and properties of the low-lying singlet and triplet excited states. The S1 ÏÏ* state has been determined to be responsible of the lowest absorption and fluorescence bands and to initially carry the population in the photophysical processes related to the phototherapeutic properties of psoralen derivatives. The low-lying T1 ÏÏ* state is, on the other hand, protagonist of the phosphorescence, and its prevalent role in the reactivity of psoralen is suggested to be related to the elongation of the pyrone ring C3âC4 bond, where the spin density is distributed on both carbon atoms. Analysis of energy gaps and spin-orbit coupling elements indicates that the efficient photophysical process leading to the population of the lowest triplet state does not take place at the Franck-Condon region but along the S1 relaxation [email protected] [email protected] [email protected]
Electronic sculpting of ligand-GPCR subtype selectivity:the case of angiotensin II
GPCR subtypes possess distinct functional
and pharmacological profiles,
and thus development of subtype-selective ligands has immense therapeutic
potential. This is especially the case for the angiotensin receptor
subtypes AT1R and AT2R, where a functional negative control has been
described and AT2R activation highlighted as an important cancer drug
target. We describe a strategy to fine-tune ligand selectivity for
the AT2R/AT1R subtypes through electronic control of ligand aromatic-prolyl
interactions. Through this strategy an AT2R high affinity (<i>K</i><sub>i</sub> = 3 nM) agonist analogue that exerted 18,000-fold
higher selectivity for AT2R versus AT1R was obtained. We show that
this compound is a negative regulator of AT1R signaling since it is
able to inhibit MCF-7 breast carcinoma cellular proliferation in the
low nanomolar range
The Autism Diagnostic Observation Schedule, Module 4:Application of the Revised Algorithms in an Independent, Well-Defined, Dutch Sample (n=93)
This study examined the discriminative ability of the revised Autism Diagnostic Observation Schedule module 4 algorithm (Hus and Lord in J Autism Dev Disord 44(8):1996-2012, 2014) in 93 Dutch males with Autism Spectrum Disorder (ASD), schizophrenia, psychopathy or controls. Discriminative ability of the revised algorithm ASD cut-off resembled the original algorithm ASD cut-off: highly specific for psychopathy and controls, lower sensitivity than Hus and Lord (2014; i.e. ASD .61, AD .53). The revised algorithm AD cut-off improved sensitivity over the original algorithm. Discriminating ASD from schizophrenia was still challenging, but the better-balanced sensitivity (.53) and specificity (.78) of the revised algorithm AD cut-off may aide clinicians' differential diagnosis. Findings support using the revised algorithm, being conceptually conform the other modules, thus improving comparability across the lifespan
Control of primary productivity and the significance of photosynthetic bacteria in a meromictic kettle lake.
During 1986 planktonic primary production and controlling factors were investigated in a small (A0 = 11.8 · 103 m2, Zmax = 11.5 m) meromictic kettle lake (Mittlerer Buchensee). Annual phytoplankton productivity was estimated to ca 120 gC · mâ2 · aâ1 (1,42 tC · lakeâ1 · aâ1). The marked thermal stratification of the lake led to irregular vertical distributions of chlorophylla concentrations (Chla) and, to a minor extent, of photosynthesis (Az). Between the depths of 0 to 6 m low Chla concentrations (< 7 mg · mâ3) and comparatively high background light attenuation (kw = 0,525 mâ1, 77% of total attenuation due to gelbstoff and abioseston) was found. As a consequence, light absorption by algae was low (mean value 17,4%) and self-shading was absent.
Because of the small seasonal variation of Chla concentrations, no significant correlation between Chla and areal photosynthesis (A) was observed. Only in early summer (JuneâJuly) biomass appears to influence the vertical distribution of photosynthesis on a bigger scale. Around 8 m depth, low-light adapted algae and phototrophic bacteria formed dense layers. Due to low ambient irradiances, the contribution of these organisms to total primary productivity was small. Primary production and incident irradiance were significantly correlated with each other (r2 = 0.68). Although the maximum assimilation number (Popt) showed a clear dependence upon water temperature (Q10 = 2.31), the latter was of minor importance to areal photosynthesis
Atmospheric stilling offsets the benefits from reduced nutrient loading in a large shallow lake
As part of a global phenomenon, a 30% decrease in average wind speed since 1996 in southern Estonia
together with more frequent easterly winds resulted in 47% decrease in bottom shear stress in the large
(270 km2), shallow (mean depth 2.8 m), and eutrophic Lake VÔrtsjÀrv. Following a peak in eutrophication pressure
in the 1970sâ80s, the concentrations of total nutrients were declining. Nonmetric Multidimensional Scaling
(NMDS) ordination of a 54-year phytoplankton community composition time-series (1964â2017) revealed
three distinct periods with breaking points coinciding with changes in wind and/or water level. Contrary to
expectations, we detected no decrease in optically active substances that could be related to wind stilling,
whereas phytoplankton biomass showed an increasing trend despite reduced nutrient levels. Here we show how
opening of the âlight niche,â caused by declining amount of suspended sediments, was capitalized and filled by
the light-limited phytoplankton community. We suggest that wind stilling is another global factor, complementary
to climate warming that counteracts eutrophication mitigation in lakes and may provide a challenge to
assessment of the lake ecological status.Main financial support for EMU: European Unionâs Horizon 2020 research and innovation programme Under the Marie SkĆodowska-Curie Action, Innovative Training Networks, European Joint Doctorates.Project name, acronym and grant number: Management of climatic extreme events in lakes and reservoirs for the protection of ecosystem services, MANTEL, grant agreement No 722518.Publication date and, if applicable, length of embargo period: Published as Early View on 07.10.2019, no embargo period.Main financial support for EMU: European Unionâs Horizon 2020 research and innovation programme Under the Marie SkĆodowska-Curie Action, Innovative Training Networks, European Joint Doctorate
Author correction : a global database for metacommunity ecology, integrating species, traits, environment and space
Correction to: Scientific Data https://doi.org/10.1038/s41597-019-0344-7, published online 08 January 202
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