5,600 research outputs found
The effect of cation substitution on the local coordination of protons in Ba2In1.85M0.15O6H2 (M = In, Ga, Sc and Y)
No full textWe report on an investigation of the local structure and vibrational dynamics in the brownmillerite-based proton conductors Ba2In1.85M0.15O6H2 with M = In, Ga, Sc and Y. The aim is to determine the effect of the cation (M) substitution on the local coordination environment of the protons. The techniques used are infrared spectroscopy and inelastic neutron scattering. The materials are characterized by two main types of proton sites, denoted as H (1) and H(2), which are featured by different local structures. We establish that the relative population of these two proton sites varies as a function of M. Specifically, it is found that, with respect to Ba2In2O6H2, the relative population of H(1) protons increases upon the substitution of In with any of the three different cations. The strongest effect is observed for M = Ga and Sc, whereas the effect observed for M = Y is minor. This new insight motivates efforts to unravel the mobility of the two types of protons, since then cation modification would offer a rational route for improving the proton conductivity of these types of materials
Predictors of “brain fog” 1 year after COVID-19 disease
No full textIntroduction: Brain fog has been described up to 1 year after SARS-CoV-2 infection, notwithstanding the underlying mechanisms are still poorly investigated. In this study, we aimed to evaluate the prevalence of cognitive complaints at 1-year follow-up and to identify the factors related to persistent brain fog in COVID-19 patients. Methods: Out of 246 COVID patients, hospitalized from March 1st to May 31st, a sample of 137 patients accepted to be evaluated at 1 year from discharge, through a full clinical, neurological, and psychological examination, including the Montreal Cognitive Assessment (MoCA), impact of event scale-revised (IES-R), Zung self-rating depression scale (SDS), Zung self-rating anxiety scale (SAS), and fatigue severity scale (FSS). Subjects with prior cognitive impairment and/or psychiatric disorders were excluded. Results: Patients with cognitive disorders exhibited lower MoCA score (22.9 ± 4.3 vs. 26.3 ± 3.1, p = 0.002) and higher IES-R score (33.7 ± 18.5 vs. 26.4 ± 16.3, p = 0.050), SDS score (40.9 ± 6.5 vs. 35.5 ± 8.6, p = 0.004), and fatigue severity scale score (33.6 ± 16.1 vs. 23.7 ± 12.5, p = 0.001), compared to patients without cognitive complaints. Logistic regression showed a significant correlation between brain fog and the self-rating depression scale values (p = 0.020), adjusted for age (p = 0.445), sex (p = 0.178), premorbid Cumulative Illness Rating Scale (CIRS) (p = 0.288), COVID-19 severity (BCRSS) (p = 0.964), education level (p = 0.784) and MoCA score (p = 0.909). Conclusions: Our study showed depression as the strongest predictor of persistent brain fog, adjusting for demographic and clinical variables. Wider longitudinal studies are warranted to better explain cognitive difficulties after COVID-19
SC author and illustrator Kate Salley Palmer signing book
No full textPhotograph of SC author and illustrator Kate Salley Palmer signing boo
Book signing by SC author and illustrator Kate Salley Palmer
No full textPhotograph of Book signing by SC author and illustrator Kate Salley Palme
High-resolution clean-sc
No full textIn this paper a high-resolution extension of CLEAN-SC is proposed: HR-CLEAN-SC. Where CLEAN-SC uses peak sources in “dirty maps” to define so-called source components, HR-CLEAN-SC takes advantage of the fact that source components can likewise be derived from points at some distance from the peak, as long as these “source markers” are on the main lobe of the Point Spread Function (PSF). This is very useful when sources are closely spaced together, such that their PSFs interfere. Then, alternative markers can be sought in which the relative influence by PSFs of other source positions is minimised. For those markers the source components better agree with the actual sources, which allows for better estimation of their locations and strengths. This paper outlines the theory needed to understand this approach and discusses applications to 2D and 3D microphone array simulations with closely spaced sources
SC author and illustrator Kate Salley Palmer talking to event attendees
No full textPhotograph of SC author and illustrator Kate Salley Palmer talking to Rita Lewi
Ca-modified Al–Mg–Sc alloy with high strength at elevated temperatures due to a hierarchical microstructure
No full textAl-Mg alloys are normally prone to lose part of their yield and tensile strength at high temperatures due to insufficient thermal stability of the microstructure. Here, we present a Ca-modified Al–Mg–Sc alloy demonstrating high strength at elevated temperatures. The microstructure contains Al4Ca phases distributed as a network along the grain boundary and Al3(Sc,Zr) nano-particles dispersed within the grains. The microstructure evolution and age-hardening analysis indicate that the combination of an Al4Ca network and Sc-rich nano-particles leads to excellent thermal stability even upon aging at 300 °C. The tensile strength of the alloy for temperatures up to 250 °C is significantly improved by an aging treatment and is comparable with the commercial heat-resistant aluminum alloys, i.e., A356 and A319. At a high temperature of 300 °C, the tensile strength is superior to the above-mentioned commercial alloys, even more so when expressed as the specific strength due to the low density of Ca-modified Al–Mg–Sc alloy. The excellent high-temperature strength results from a synergistic effect of solid solution strengthening, grain boundary strengthening and nanoparticle order strengthening.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Novel Aerospace Material
SC-Square: Overview to 2021.
No full textThis extended abstract was written to accompany an invited talk at the 2021 SC-Square Workshop, where the author was asked to give an overview of SC-Square progress to date. The author first reminds the reader of the definition of SC-Square, then briefly outlines some of the history, before picking out some (personal) scientific highlights
SC-Square: Overview to 2021.
No full textThis extended abstract was written to accompany an invited talk at the 2021 SC-Square Workshop, where the author was asked to give an overview of SC-Square progress to date. The author first reminds the reader of the definition of SC-Square, then briefly outlines some of the history, before picking out some (personal) scientific highlights
Synthesis of a highly reactive form of WO2Cl2, its conversion into nanocrystalline mono-hydrated WO3 and coordination compounds with tetramethylurea
No full textA new form of WO2Cl2 was obtained by modification of a literature procedure. Both the newly prepared WO2Cl2 and the commercial yellow WO2Cl2 exhibited an orthorhombic structure (powder X-ray diffraction, P-XRD), and their air exposure at room temperature afforded light green and lemon yellow WO3·H2O (orthorhombic phase), respectively. These materials were characterized by P-XRD, high-resolution transmission electron microscopy (HR-TEM) and scanning transmission electron microscopy (S-TEM). The analyses revealed the nanocrystalline nature of light green WO3·H2O, and the prevalent amorphism of lemon yellow WO3·H2O. The reactions of grey WO2Cl2 with one and two equivalents of tetramethylurea (tmu), in CH2Cl2 at room temperature, led to the isolation of the trinuclear complex [WO2Cl2(tmu)]3, 1 (45% yield), and the mononuclear one WO2Cl2(tmu)2, 2 (64%), respectively. Compounds 1 and 2 were fully characterized by analytical and spectroscopic methods, single crystal X-ray diffraction (SC-XRD) and DFT calculations
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