Understanding the behaviour of graphene oxide in Portland cement paste

This study reports on the effect of graphene oxide (GO) on the hydration of Portland cement (PC) and industrial clinker. GO accelerates PC hydration, whereas it temporarily retards that of clinker. This difference reflects a twofold behaviour of GO in cement pastes. Retardation is due to the interaction of GO with the surface of hydrating grains, while acceleration results from a seeding effect. Gypsum causes this difference. GO is shown to have little effect on the strength of hardened pastes, and this merely relates to the change of hydration degree, as opposed to reinforcing effect formerly assumed. Overall, GO is not particularly active as a nucleation surface, as it aggregates and behaves in a similar way to inert fillers (e.g. quartz). Polycarboxylate-ether copolymer could make GO an active seed in cement pastes, as it prevents GO from aggregating. Nevertheless, this was found to occur only in alite pastes but not PC pastes

Finding core-periphery structures with node influences

Detecting core-periphery structures is one of the outstanding issues in complex network analysis. Various algorithms can identify core nodes and periphery nodes. Recent advances found that many networks from real-world data can be better modeled with multiple pairs of core-periphery nodes. In this study, we propose to use an influence propagation process to detect multiple pairs of core-periphery nodes. In this framework, we assume each node can emit a certain amount of influence and propagate it through the network. Then we identify nodes with large influences as core nodes, and we utilize a maximum influence chain to construct a node-pairing network to determine core-periphery pairs. This approach can take node interactions into consideration and can reduce noises in finding pairs. Experiments on randomly generated networks and real-world networks confirm the efficiency and accuracy of our algorithm

More than words: word predictability, prosody, gesture and mouth movements in natural language comprehension

The ecology of human language is face-to-face interaction, comprising cues such as prosody, co-speech gestures and mouth movements. Yet, the multimodal context is usually stripped away in experiments as dominant paradigms focus on linguistic processing only. In two studies we presented video-clips of an actress producing naturalistic passages to participants while recording their electroencephalogram. We quantified multimodal cues (prosody, gestures, mouth movements) and measured their effect on a well-established electroencephalographic marker of processing load in comprehension (N400). We found that brain responses to words were affected by informativeness of co-occurring multimodal cues, indicating that comprehension relies on linguistic and non-linguistic cues. Moreover, they were affected by interactions between the multimodal cues, indicating that the impact of each cue dynamically changes based on the informativeness of other cues. Thus, results show that multimodal cues are integral to comprehension, hence, our theories must move beyond the limited focus on speech and linguistic processing

“We’re not just sat at home in our pyjamas!”: a thematic analysis of the social lives of home educated adolescents in the UK

A common perception of home education is that despite potential beneficial educational outcomes, children who are home educated lack social experiences and therefore show poor social development. However, previous research in this area suggests that home educated children demonstrate a range of age-appropriate social skills. This research has mainly focused on children younger than twelve, thus we have much less of an understanding of the social impacts of home education on adolescents. Furthermore, previous research has often used social skills questionnaires and has not explored the experiences of home educating families from their own perspectives. The current study addresses these gaps in the literature by interviewing three home educated adolescents and their mothers about their social experiences and development with the research question of ‘how do home educated adolescents and their parents experience and understand socialisation?’. In one-to-one interviews, young people (aged 11–14) were asked about their experiences and perceptions of their social lives. In a separate interview, mothers were asked about how they facilitated these social experiences and their perceptions of the impact this had on their child’s development. Data from the interviews was thematically analysed. Results suggested that adolescents participated in a range of social experiences that promoted their social skills, happiness and confidence. Participants felt that this created a positive social environment and sense of community, and encouraged the adolescents to interact with a diverse range of people. However, further research is needed to explore whether this finding is generalisable to the broader community of home educated adolescents

What emotional-centred challenges do children attending special schools face over primary–secondary school transition?

© 2021 The Authors. Journal of Research in Special Educational Needs published by John Wiley & Sons Ltd on behalf of National Association for Special Educational Needs. Primary–secondary school transition encompasses multiple social, academic and environmental changes which can negatively impact children’s emotional well-being. Children with Social, Emotional and Mental Health difficulties (SEMH) are believed to be especially vulnerable during this time. However, the voices of children with SEMH are heavily underrepresented in this field within practice and research. The present case study examined how children with SEMH difficulties within one special school experience primary–secondary school transition and how they are supported, in order to make recommendations to improve this period. The case study was qualitative and longitudinal, conducted over 18-months and methodologies included ethnographic observations, child photo-elicitation focus groups (with 11 Year 6 children) and three adult interviews. Findings demonstrated that over primary–secondary school transition children with SEMH difficulties (a) negotiate significant structural changes in support (often unanticipated) and (b) need to feel a sense of safety and belonging. To manage this effectively, transition provision for children with SEMH difficulties needs to consider their short-term emotional well-being whilst still in primary school, in addition to their long-term well-being looking ahead to secondary school. Greater collaboration and communication across schools and stakeholders can help ensure children receive continuity in standards and support

Making a difference with psychology: case study

No abstract available

An investigation into the colloidal stability of graphene oxide nano-layers in alite paste

Recent studies have reported that graphene oxide (GO) is capable of enhancing the mechanical properties of hardened Portland cement (PC) pastes. The mechanisms proposed so far to explain this strengthening generally assume that GO is well dispersed in the pore solution of PC paste, serving as a reinforcing agent or nucleation-growth site during hydration. This paper investigates (i) the effect of GO on the hydration of alite, the main constituent of PC cement, using isothermal calorimetry and boundary nucleation-growth modelling, and (ii) the factors controlling the colloidal stability of GO in alite paste environment. Results indicate that GO accelerates the hydration of alite only marginally, and that GO is susceptible to aggregation in alite paste. This instability is due to (i) a pH-dependent interaction between GO and calcium cations in the pore solution of alite paste, and (ii) a significant reduction of GO functional groups at high pH

Design of hyperporous graphene networks and their application in solid-amine based carbon capture systems

We demonstrate a simple and fully scalable method for obtaining hierarchical hyperporous graphene networks of ultrahigh total pore volume by thermal-shock exfoliation of graphene-oxide (exfGO) at a relatively mild temperature of 300 °C. Such pore volume per unit mass has not previously been achieved in any type of porous solid. We find that the amount of oxidation of starting graphene-oxide is the key factor that determines the pore volume and surface area of the final material after thermal shock. Specifically, we emphasize that the development of the hyperporosity is directly proportional to the enhanced oxidation of sp2 C[double bond, length as m-dash]C to form C[double bond, length as m-dash]O/COO. Using our method, we reproducibly synthesized remarkable meso-/macro-porous graphene networks with exceptionally high total pore volumes, exceeding 6 cm3 g−1. This is a step change compared to ≤3 cm3 g−1 in conventional GO under similar synthetic conditions. Moreover, a record high amine impregnation of >6 g g−1 is readily attained in exfGO samples (solid-amine@exfGO), where amine loading is directly controlled by the pore-structure and volume of the host materials. Such solid-amine@exfGO samples exhibit an ultrahigh selective flue-gas CO2 capture of 30–40 wt% at 75 °C with a working capacity of ≈25 wt% and a very long cycling stability under simulated flue-gas stream conditions. To the best of our knowledge, this is the first report where a graphene-oxide based hyperporous carbon network is used to host amines for carbon capture application with exceptionally high storage capacity and stability

Crystal Structure of the Sodium Cobaltate Deuterate Superconductor NaxCoO2o4xD2O (x=1/3)

Neutron and x-ray powder diffraction have been used to investigate the crystal structures of a sample of the newly-discovered superconducting sodium cobaltate deuterate compound with composition Na0.31(3)CoO2o1.25(2)D2O and its anhydrous parent compound Na0.61(1)CoO2. The deuterate superconducting compound is formed by coordinating four D2O molecules (two above and two below) to each Na ion in a way that gives Na-O distances nearly equal to those in the parent compound. One deuteron of the D2O molecule is hydrogen bonded to an oxygen atom in the CoO2 plane and the oxygen atom and the second deuteron of each D2O molecule lie approximately in a plane between the Na layer and the CoO2 layers. This coordination of Na by four D2O molecules leads to ordering of the Na ions and D2O molecules. The sample studied here, which has Tc=4.5 K, has a refined composition of Na0.31(3)CoO2o1.25(2)D2O, in agreement with the expected 1:4 ratio of Na to D2O. These results show that the optimal superconducting composition should be viewed as a specific hydrated compound, not a solid solution of Na and D2O (H2O) in NaxCoO2oyD2O. Studies of physical properties vs. Na or D2O composition should be viewed with caution until it is verified that the compound remains in the same phase over the composition range of the study.Comment: 22 pages, 8 figure

Size-Related Electrochemical Performance in Active Carbon Nanostructures: A MOFs-Derived Carbons Case Study

Metal–organic framework–derived carbon nanostructures have generated significant interest in electrochemical capacitors and oxygen/hydrogen catalysis reactions. However, they appear to show considerably varied structural properties, and thus exhibit complex electrochemical–activity relationships. Herein, a series of carbon polyhedrons of different sizes, between 50 nm and µm, are synthesized from zeolitic imidazolate frameworks, ZIF-8 (ZIF-derived carbon polyhedrons, ZDCPs) and their activity is studied for capacitance and the oxygen reduction reaction (ORR). Interestingly, a well-correlated performance relationship with respect to the particle size of ZDCPs is evidenced. Here, the identical structural features, such as specific surface area (SSA), microporosity, and its distribution, nitrogen doping, and graphitization are all strictly maintained in the ZDCPs, thus allowing identification of the effect of particle size on electrochemical performance. Supercapacitors show a capacity enhancement of 50 F g−1 when the ZDCPs size is reduced from micrometers to ≤200 nm. The carbonization further shows a considerable effect on rate capacitance—ZDCPs of increased particle size lead to drastically reduced charge transportability and thus inhibit their performance for both the charge storage and the ORR. Guidelines for the capacitance variation with respect to the particle size and SSA in such carbon nanostructures from literature are presented