This work aims to clarify the impact of alkali and sulfate on the hydration kinetics and microstructural development of alite. The plain alite system is compared to systems with addition of: i) ...gypsum, ii) Na2SO4, iii) NaOH plus gypsum and iv) NaOH. In all the cases a clear early acceleration of the hydration rate is observed. Alkalis increase the solubility of aluminate and this further inhibits the silicate reaction at later ages. This inhibition does not take place with sulfate, where ettringite is precipitated lowering the aluminate concentration in solution. Major differences in the morphology of hydrates are observed (C-S-H and portlandite). Sulfate uptake leads to a divergent needle-like C-S-H compared to the convergent needles in plain alite. In the presence of NaOH without sulfate, C-S-H tends towards a foil-like morphology. The highest mechanical strength obtained with the combination of alkalis and sulfate is not dependent on the morphology of C-S-H.
This work clarifies the impact of NaOH and Na2SO4 on the kinetics and microstructural development of cement hydration to better understand their effect on the mechanical properties. Na2SO4 and NaOH ...accelerate hydration and strength development during the first hours but lower strength values later on. For the same degree of hydration of cement, the addition of Na2SO4 leads to the same compressive strength as the alkali free system while NaOH clearly lowers it. Compressive strengths closely correlate to the total capillary porosity of the cement paste, which relates to the total volume of hydrates. Na2SO4 promotes the precipitation of a higher volume of hydrates, especially ettringite. A higher volume of hydrates can better fill the space, decrease porosity and consequently increase strength. Contrary, NaOH lowers the total volume of hydrates, mainly the volume of ettringite. Strength differences are not dependent on the bulk density, chemical composition or morphology of C-S-H.
Schizophrenia (SZ) is a severe mental disorder associated with a variety of linguistic deficits, and recently it has been suggested that these deficits are caused by an underlying impairment in the ...ability to build complex syntactic structures and complex semantic relations. Aiming at contributing to determining the specific linguistic profile of SZ, we investigated the usage of pronominal subjects and sentence types in two corpora of oral dream and waking reports produced by speakers with SZ and participants without SZ (NSZ), both native speakers of Brazilian Portuguese. Narratives of 40 adult participants (20 SZ, and 20 NSZ–sample 1), and narratives of 31 teenage participants (11 SZ undergoing first psychotic episode, and 20 NSZ–sample 2) were annotated and statistically analyzed. Overall, narratives of speakers with SZ presented significantly higher rates of matrix sentences, null pronouns—particularly null 3Person referential pronouns—and lower rates of non-anomalous truncated sentences. The high rate of matrix sentences correlated significantly with the total PANSS scores, suggesting an association between the overuse of simple sentences and SZ symptoms in general. In contrast, the high rate of null pronouns correlated significantly with positive PANSS scores, suggesting an association between the overuse of null pronominal forms and the positive symptoms of SZ. Finally, a cross-group analysis between samples 1 and 2 indicated a higher degree of grammatical impairment in speakers with multiple psychotic episodes. Altogether, the results strengthen the notion that deficits at the pronominal and sentential levels constitute a cross-cultural linguistic marker of SZ.
The authors examine U.S.-based evidence that connects characteristics of the social environment with outcomes across the psychosis continuum, from psychotic experiences to schizophrenia. The notion ...that inequitable social and economic systems of society significantly influence psychosis risk through proxies, such as racial minority and immigrant statuses, has been studied more extensively in European countries. While there are existing international reviews of social determinants of psychosis, none to the authors‘ knowledge focus on factors in the U.S. context specifically—an omission that leaves domestic treatment development and prevention efforts incomplete and underinformed. In this review, the authors first describe how a legacy of structural racism in the United States has shaped the social gradient, highlighting consequential racial inequities in environmental conditions. The authors offer a hypothesized model linking structural racism with psychosis risk through interwoven intermediary factors based on existing theoretical models and a review of the literature. Neighborhood factors, cumulative trauma and stress, and prenatal and perinatal complications were three key areas selected for review because they reflect social and environmental conditions that may affect psychosis risk through a common pathway shaped by structural racism. The authors describe evidence showing that Black and Latino people in the United States suffer disproportionately from risk factors within these three key areas, in large part as a result of racial discrimination and social disadvantage. This broad focus on individual and community factors is intended to provide a consolidated space to review this growing body of research and to guide continued inquiries into social determinants of psychosis in U.S. contexts.
Dream reports collected after rapid eye movement sleep (REM) awakenings are, on average, longer, more vivid, bizarre, emotional and story-like compared to those collected after non-REM. However, a ...comparison of the word-to-word structural organization of dream reports is lacking, and traditional measures that distinguish REM and non-REM dreaming may be confounded by report length. This problem is amenable to the analysis of dream reports as non-semantic directed word graphs, which provide a structural assessment of oral reports, while controlling for individual differences in verbosity. Against this background, the present study had two main aims: Firstly, to investigate differences in graph structure between REM and non-REM dream reports, and secondly, to evaluate how non-semantic directed word graph analysis compares to the widely used measure of report length in dream analysis. To do this, we analyzed a set of 133 dream reports obtained from 20 participants in controlled laboratory awakenings from REM and N2 sleep. We found that: (1) graphs from REM sleep possess a larger connectedness compared to those from N2; (2) measures of graph structure can predict ratings of dream complexity, where increases in connectedness and decreases in randomness are observed in relation to increasing dream report complexity; and (3) measures of the Largest Connected Component of a graph can improve a model containing report length in predicting sleep stage and dream report complexity. These results indicate that dream reports sampled after REM awakening have on average a larger connectedness compared to those sampled after N2 (i.e. words recur with a longer range), a difference which appears to be related to underlying differences in dream complexity. Altogether, graph analysis represents a promising method for dream research, due to its automated nature and potential to complement report length in dream analysis.
Sodium gluconate has been shown to compensate the impact of alkalis on the long term strength development of cement pastes. This work studies the impact of sodium gluconate combined with Na2SO4 on ...the microstructural development of white cement-slag systems compared to the addition of only Na2SO4 to better understand its effect on strength development. At long ages the addition of sodium gluconate in systems with Na2SO4 increases the strength compared to the systems with only Na2SO4. Differences in strength cannot be explained by changes in the degree of hydration of cement, degree of reaction of slag, phase assemblage or C-S-H morphology and chemical composition, since these parameters are not affected by sodium gluconate. 1H NMR shows that sodium gluconate increases the water amount in C-S-H and image analysis confirms the formation of a less dense C-S-H, which can better fill the space. Consequently, the porosity decreases and strength development increases.
In many field electron emission experiments on single-walled carbon nanotubes (SWCNTs), the SWCNT stands on one of two well-separated parallel plane plates, with a macroscopic field F M applied ...between them. For any given location “L” on the SWCNT surface, a field enhancement factor (FEF) is defined as F L/F M, where F L is a local field defined at “L”. The best emission measurements from small-radii capped SWCNTs exhibit characteristic FEFs that are constant (i.e., independent of F M). This paper discusses how to retrieve this result in quantum-mechanical (as opposed to classical electrostatic) calculations. Density functional theory (DFT) is used to analyze the properties of two short, floating SWCNTs, capped at both ends, namely, a (6,6) and a (10,0) structure. Both have effectively the same height (∼5.46 nm) and radius (∼0.42 nm). It is found that apex values of local induced FEF are similar for the two SWCNTs, are independent of F M, and are similar to FEF values found from classical conductor models. It is suggested that these induced-FEF values are related to the SWCNT longitudinal system polarizabilities, which are presumed similar. The DFT calculations also generate “real”, as opposed to “induced”, potential-energy (PE) barriers for the two SWCNTs, for F M values from 3 V/μm to 2 V/nm. PE profiles along the SWCNT axis and along a parallel “observation line” through one of the topmost atoms are similar. At low macroscopic fields, the details of barrier shape differ for the two SWCNT types. Even for F M = 0, there are distinct PE structures present at the emitter apex (different for the two SWCNTs); this suggests the presence of structure-specific chemically induced charge transfers and related patch-field distributions.
Corannulene has been a useful prototype for studying C-based nanostructures as well as surface chemistry and reactivity of sp2-hybridized carbon-based materials. We have investigated fluorination and ...hydrogenation of corannulene carrying out density functional theory calculations. In general, the fluorination is energetically more favorable than hydrogenation of corannulene. The substitution of the peripheral H atoms in the corannulene molecule by F atoms leads to a larger cohesive energy gain than when F (or H) atoms are bonded to the hub carbon and bridge carbon sites of this molecule. As expected for doped C-based nanostructures, the hydrogenation or fluorination significantly changes the HOMO–LUMO gap of the system. We have obtained HOMO–LUMO gap variations of 0.13–3.46 eV for F-doped and 0.38–1.52 eV for H-doped systems. These variations strongly depend on the concentration and position of the incorporated F/H atoms, instead of the structural stability of the doped systems. Considering these calculations, we avoid practical difficulties associated with the addition/substitution reactions of larger curved two-dimensional (2D) carbon nanostructures, and we obtain a comprehensive and systematic understanding of a variety of F/H 2D doped systems.
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