With a rising tide of adoption of recycled aggregate (RA) for construction, investigation on ways to improve the quality of RA has been overwhelming. The adoption of RA brings benefits including savings in the limited landfill spaces and the use of natural resources. However, the poorer quality of RA often limits its utilization to low grade applications such as sub-grade activities, filling materials and low grade concrete. The major reason that affects the quality of RA is the large amount of cement mortar remains on the surface of the aggregate, resulting in higher porosity, water absorption rates and thus a weaker interfacial zone between new cement mortar and aggregates, which weakens the strength and mechanical performance of concrete made from RA. This paper attempts to study three pre-soaking treatment approaches; namely ReMortar HCl , ReMortar H2SO4 and ReMortar H3PO4 in reducing the mortar attached to RA. The results show that the behaviour of RA has improved with reduction in water absorption, without simultaneous exceeding the limits of chloride and sulphate compositions after the treatment. This work has also compared the compressive strength, flexural strength and modulus of elasticity of concrete made from the approaches, which shows marked improvements in quality when compared with those using traditional approaches.

Owing to their molecular building blocks, yet highly crystalline nature, metal−organic frameworks (MOFs) sit at the interface between molecule and material. Their diverse structures and compositions enable them to be useful materials as catalysts in heterogeneous reactions, electrical conductors in energy storage and transfer applications, chromophores in photoenabled chemical transformations, and beyond. In all cases, density functional theory (DFT) and higher-level methods for electronic structure determination provide valuable quantitative information about the electronic properties that underpin the functions of these frameworks. However, there are only two general modeling approaches in conventional electronic structure software packages: those that treat materials as extended, periodic solids, and those that treat materials as discrete molecules. Each approach has features and benefits; both have been widely employed to understand the emergent chemistry that arises from the formation of the metal−organic interface. This Review canvases these approaches to date, with emphasis placed on the application of electronic structure theory to explore reactivity and electron transfer using periodic, molecular, and embedded models. This includes (i) computational chemistry considerations such as how functional, k-grid, and other model variables are selected to enable insights into MOF properties, (ii) extended solid models that treat MOFs as materials rather than molecules, (iii) the mechanics of cluster extraction and subsequent chemistry enabled by these molecular models, (iv) catalytic studies using both solids and clusters thereof, and (v) embedded, mixed-method approaches, which simulate a fraction of the material using one level of theory and the remainder of the material using another dissimilar theoretical implementation.

We introduce a stochastic version of Gubinelli's sewing lemma ([Gub04]), providing a sufficient condition for the convergence in moments of some random Riemann sums. Compared with the deterministic sewing lemma, adaptiveness is required and the regularity restriction is improved by a half. The limiting process exhibits a Doob-Meyer-type decomposition. Relations with Itô calculus are established. To illustrate further potential applications, we use the stochastic sewing lemma in studying stochastic differential equations driven by Brownian motions or fractional Brownian motions with irregular drifts.

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In this paper, we study a nonlinear one spatial dimensional stochastic heat equations driven by Gaussian noise: ∂u ∂t = ∂ 2 u ∂x 2 + σ(u)Ẇ , wherė W is white in time and has the covariance of a fractional Brownian motion with Hurst parameter H ∈ ( 1 4 , 1 2 ). We remove a critical and unnatural condition σ(0) = 0 previously imposed in a recent paper by Hu, Huang, Lê, Nualart and Tindel. The idea is to work on a weighted space Z p λ,T for some power decay weight λ(x) = c H (1 + |x| 2 ) H−1 . We obtain the weak existence of solution. With additional decay conditions on σ we obtain the existence of strong solution and the pathwise uniqueness of the strong solution. The reason to introduce the weight function is that the solution u(t, x) may explode as |x| → ∞ when the "diffusion coefficient" σ(u) does not satisfy σ(0) = 0 regardless of the initial condition. This motivates us to study the exact asympotics of the solution u add (t, x) as t and x go to infinity when σ(u) = 1 and when the initial condition u 0 (x) ≡ 0. In particular, we find the exact growth of sup |x|≤L |u add (t, x)|. Furthermore, we find the sharp growth rate for the Hölder coefficients, namely, sup |x|≤L |u add (t,x+h)−u add (t,x)| |h| β and sup |x|≤L |u add (t+τ,x)−u add (t,x)| τ α . These results are interesting and fundamental themselves.