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The combined utilization of mineral accelerators and nano-seeding materials is a novel method to promote the early strength of cement-based materials. In this paper, the effects of nano-C-S-H seed (NCS) on the early compressive strength of the Portland cement (PC)– calcium sulfoaluminate cement (CSA) binder were investigated. The results showed that NCS and CSA synergistically contributed to the early strength of PC. In detail, a 326.3% increase in the 10 h compressive strength of PC paste was obtained through the addition of NCS (2 wt%) and CSA (5%) in common. This was higher than the sum of the increases observed with the single additions of CSA (157.9%) or NCS (87.6%), with the same above dosage, in PC. Meanwhile, the early strength enhancement effects of NCS and CSA, when used together in PC, lasted longer than the effects of either used alone. Moreover, the synergetic effect mechanism was analyzed by isothermal calorimeter, QXRD, TGA, MIP, and SEM techniques. The calorimetry, XRD, and TGA results demonstrated that the synergistic mechanism was associated with the synergistic promotion effects of CSA and NCS on the hydrates. The fast hydration of CSA produced large amounts of ettringite and also consumed partial free water to promote the performance of the seeding effect of NCS which, simultaneously, further accelerated the precipitation of C-S-H gel and CH. The high alkie environment was also beneficial for the continuous generation of ettringite. In addition, the results of MIP and SEM measurements showed that the micro-filling effect of NCS significantly optimized the pore structure of a PC-CSA blend-hardened paste. Thus, the synergistic strength enhancement effects of CSA and NCS on PC were attributed to the matching of the promotion of hydration generation and the optimization of pore structures in hardening cement paste. The results of this article provide a new approach to achieving the rapid development of the early strength of cementitious materials, with potential applications in precast concrete and low-temperature construction.

This study aims to analyze the effect of high-altitude environment on drivers’ mental workload (MW), situation awareness (SA), and driving behaviour (DB), and to explore the relationship among those driving performances. Based on a survey, the data of 356 lowlanders engaging in driving activities at Tibetan Plateau (high-altitude group) and 341 lowlanders engaging in driving activities at low altitudes (low-altitude group) were compared and analyzed. The results suggest that the differences between the two groups are noteworthy. Mental workload of high-altitude group is significantly higher than that of low-altitude group, and their situation awareness is lower significantly. The possibility of risky driving behaviours for high-altitude group, especially aggressive violations, is higher. For the high-altitude group, the increase of mental workload can lead to an increase on aggressive violations, and the situation understanding plays a full mediating effect between mental workload and aggressive violations. Measures aiming at the improvement of situation awareness and the reduction of mental workload can effectively reduce the driving risk from high-altitude environment for lowlanders.

Isophorone diisocyanate (IPDI) was encapsulated successfully within double-layered shells, and final microcapsules showed outstanding self-healing functions in cement paste. The well-disper...

For two graphs $G,H$ and a positive integer $k$, the \emph{Gallai-Ramsey number} $\operatorname{gr}_k(G,H)$ is defined as the minimum number of vertices $n$ such that any $k$-edge-coloring of $K_n$ contains either a rainbow (all different colored) copy of $G$ or a monochromatic copy of $H$. If $G$ and $H$ are both complete graphs, then we call it Gallai-Ramsey function. Fox and Sudakov proved $\operatorname{gr}_k(K_s,K_t)\leq s^{4kt}$. Alon et al. showed that $\operatorname{gr}_k(K_s,K_t)\leq (2s^3+4s^2)^{kt}$. In this paper, we prove that $\operatorname{gr}_k(K_s,K_t)\leq 2^{kt}s^{3kt}$ for $t\geq 47$. We also give better upper bounds for $\operatorname{gr}_k(G,H)$ when $G,H$ are some special graphs. In this paper, we derive some lower bounds for Gallai-Ramsey functions and numbers by Lov\'{a}sz Local Lemma., Comment: 17 pages

Metal shell microcapsules containing liquid 4,4′-bis-methylene cyclohexane diisocyanate (HMDI) were successfully synthesized by plating chemically a layer of Ni-P alloy on microcapsules surfaces. The metal shell occupied around 66.0 wt% of final microcapsules, providing great potential to improve microcapsules robustness. Final microcapsules with diameters of 184.3 ± 41.7 µm had a core fraction of 22.4 ± 0.6 wt%. The final microcapsule shells with a total thickness of 7.4 ± 0.4 µm was a three-layered structure, which comprised of an outer-layered Ni-P shell with a thickness of 5.5 ± 0.2 µm, a medium-layered PUF shell with a thickness of 369.0 ± 21.0 nm, and an inner-layered polyurea shell with a thickness of 1.7 ± 0.2 µm. More interestingly, final microcapsules remained stable core fraction and morphologies in most regular solvents including low polar organic solvents, high polar organic solvents, and water. The shell strength of final microcapsules was 28.5 ± 10.3 MPa, comparing with 6.6 ± 2.5 MPa of polymer shells. Moreover, the modulus of epoxy composites was stable relatively with microcapsules concentrations. Scratched self-healing epoxy coatings showed satisfactory anticorrosion performance in salty water (1 M).

It is unclear whether the utilisation of fly ash as valuable resource is preferable to landfill disposal from the resource perspective. The objective of this study was to evaluate and compare the r...

A facile method to control the morphology of FeNi3 nanoparticles by solution reduction reaction is presented. The spherical to platelet FeNi3 particles were obtained by changing pH from 11.5 to12.5 with 0.16 mol/L of hydrazine under ultrasound irradiation, with the ratio of Fe2+ to Ni2+ as 1:3. The amount of hydrazine had little influence on the morphology of the particles. The saturation magnetization (Ms) and coercive force (Hc) of the platelet particles were 59 emu/g and 120 Oe, respectively. The real part μ’ of the permeability of the platelet particles was about 2.43–2.71 and was frequency-independent in the range of 0.1–1.0 GHz. The imaginary part (μ”) of the particles showed increase from 0.04 to 2.14 within the same frequency range.

For a given prime $p$, we study the properties of the $p$-dissection identities of Ramanujan's theta functions $\psi(q)$ and $f(-q)$, respectively. Then as applications, we find many infinite family of congruences modulo 2 for some $\ell$-regular partition functions, especially, for $\ell=2,4,5,8,13,16$. Moreover, based on the classical congruences for $p(n)$ given by Ramanujan, we obtain many more congruences for some $\ell$-regular partition functions.