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With the promotion of sustainability in the buildings and construction sector, the carbon saving strategies for the end-of-life (EoL) phase have been receiving increasing attention. In this research, life cycle assessment (LCA) theory was employed to study and compare the carbon savings benefits of three different management strategies (i.e., recycling, remanufacturing, and reuse) on the EoL phase of various buildings (including residential, office, commercial, and school buildings). Moreover, the carbon savings potential (CSP) was calculated and analyzed, which is defined as the percentage of the actual carbon savings to the sum of the total embodied carbon of the building. Results show that compared with traditional demolition and landfill treatment, the implementation of integrated management strategies for residential, office, commercial, and school buildings can reduce carbon emissions by 193.5–526.4 kgCO2-e/m2. Among the building materials, steel bar, structural steel, and concrete account for the major proportion of the total carbon savings of buildings (81.5–93.2%). The sequence of the CSPs for the four types of buildings, in descending order, is school, residential, commercial, and office buildings. A building with a life span of 50 years has the greatest CSP. The results of the study can be used to reduce environmental impacts, and have broad positive implications in terms of sustainable construction. [ABSTRACT FROM AUTHOR]

Chemodynamic therapy (CDT), utilizing Fenton catalysts to convert intracellular H2O2 into toxic hydroxyl radicals (˙OH) to kill cancer cells, has a wide application prospect in tumor treatment because of its high selectivity. Its anticancer effect, however, is unsatisfactory due to the overexpressed glutathione (GSH). Herein, a GSH-depleting Cu(II)-half-salamo-based coordination polymer (CuCP) was prepared and validated by single crystal X-ray crystallography, Hirshfeld surface analyses and DFT calculations. The Cu(II) ions in the coordination polymer are five-coordinated bearing slightly twisted square pyramidal coordination environments and are bridged by phenoxy and alkoxy groups. After internalization by tumor cells, the CuCP could be biodegraded and reduced by GSH to generate a large amount of Cu(I), simultaneously depleting GSH. Subsequently, the Cu(I) ions interact with H2O2 to generate toxic ˙OH through a Fenton-like reaction to enhance their anticancer efficacy. Our study provides useful insights into designing smarter metal-based anticancer agents to improve the CDT efficiency in cancer therapy. [ABSTRACT FROM AUTHOR]

Agglomerated carbon nanotube (CNT) powder was scattered into a cement paste layer-by-layer to form layer-distributed CNT composite (LDCC) as intelligent cement-based sensor. The characteristic of the CNT agglomerations and its effect on the mechanical and piezoresistive properties of cement paste were investigated in this study, and the results were compared with those of uniformly-dispersed CNT composites (UDCC). Based on the statistics of CNT agglomerations, it was found that the sizes of agglomerations varied from several to dozens of micrometres. The larger sized agglomerations with poorer roundness exhibited a higher possibility to cause the pores or voids accompanied with stress concentration when subjected to external forces. Hence, it is necessary to control the agglomeration sizes to reduce the porosity with edges and corners. The UDCC reached the highest compressive strength, followed by the plain cement paste and then LDCC. The mechanical strength of LDCC decreased with the increase of CNT layers. The piezoresistivity occurred in both the UDCC and LDCC, with the former possessing stable and repeatable performance. In addition, the strain-sensing ability of LDCC with moderate CNT layers presented similar sensing efficiency and repeatability to that of UDCC. The related results provide insight into the intelligent cement-based sensors with layer-distributed CNT and agglomerations, which can improve the efficiency and effectively reduce the cost for practical application. [ABSTRACT FROM AUTHOR]

Sulfuric acid corrosion on concrete structures is more prevalent and its damage evaluation becomes gradually imperative. This study attempts to characterize the sulfuric acid corroded surfaces of concrete in terms of three-dimensional fractal dimension. Accelerated sulfuric acid corrosion tests were conducted using concrete cylinders with six different corrosion durations, and the 3D coordinates of points on the surface of cylinders were captured using 3D laser scanning technique. The fractal dimensions were calculated using the cubic covering method, and the corrosion depth and mass loss of concrete were obtained correspondingly. The results indicated that fractal dimension can be considered as an indicator to evaluate the corrosion deterioration. The surface fractal dimension was positively correlated with the corrosion duration by a power function, where the value increased dramatically in the early stage, and gradually slowed down to maintain constant. Therefore, empirical functions to evaluate the corrosion depth and mass loss of concrete after sulfuric acid attacks were proposed. The parameters to establish the equivalent accelerated relation between experimental and natural conditions were also recommended under different degradation degrees. [ABSTRACT FROM AUTHOR]

The fractional changes of resistivity (FCR) of cement-based sensors with various carbon black (CB) contents were firstly investigated under uniaxial compression in this study. Then the piezoresistive behaviours of embedded cement-based sensors in unreinforced small-scale concrete beams were investigated under flexural bending load. As for the embedded cement-based sensors in the compression zones of the beam, the stress magnitude and crack failure initiation of the beams can be detected and monitored by a gradual decrease and then a sharp increase in the FRC. On the other hand, as for the counterpart sensors in the tension zones of the beam, the stress magnitude and crack failure initiation can be recognized by the gradual increase in resistivity and then a rapid jump in the FRC. During the stress monitoring of the concrete beam, the FCR values of cement-based sensors in both the compression and tension zones were consistent with the flexural stress changes, which exhibit acceptable sensitivity and reversibility. Moreover, very firm and dense interfaces in the boundaries indicate the excellent cohesion between embedded CB/cement-based sensors and beams. The related results demonstrate that the CB/cement-based sensors embedded in concrete exhibit excellent piezoresistive behaviours to potentially monitor the stress magnitude and failure process of concrete structures and pavements. [ABSTRACT FROM AUTHOR]

The effects of conductive rubber crumbs on the mechanical properties and self-sensing capacities of cementitious composites are investigated in this study. The rubberized cementitious composites with five different contents of conductive rubber crumbs are incorporated, ranging from 0%, 10%, 20%, 30% and 40% by mass of fine aggregate. Under the uniaxial cyclic compression, all the conductive rubber crumbs–filled cement composites exhibit excellent repeatability of piezoresistivity. The mortar with 20% conductive rubber crumbs at a water-to-binder ratio of 0.42 displayed the best piezoresistive sensitivity. Based on the relative positions of conductive rubber crumbs in the rubberized cement mortar, three conductive mechanisms were proposed for the conductive rubber crumbs, including complete isolation state, neighbouring state and the contact state. The isolation state plays a dominant role when the content of the conductive rubber crumbs is low, in which the piezoresistive behaviour is mainly controlled by the resistivity changes in cement matrix. In the neighbouring state, pores or voids in the gaps between nearby conductive rubber crumbs make the conductive rubber crumbs easier to connect, thus decreasing the resistivity under uniaxial compression. As for the contact state, the decreased contact resistance and the absence of sand between conductive rubber crumbs lead to higher resistivity changes under cyclic compression. The related results indicate that conductive rubber crumbs in cement mortar have application potentials for structural health monitoring. [ABSTRACT FROM AUTHOR]

In the present work, the danthron molecule (1,8-dihydroxyanthraquinone, DT) with multi-electron redox centers as a novel organic electrochemically active material for supercapacitors has been decorated on reduced graphene oxide nanosheets (RGNs) via a facile one-step reflux method. The resultant danthron functionalized RGNs (DT–RGNs) composite electrode material not only provided a fast and reversible 4e−/4H+ redox reaction because of two types of redox-active organic functional groups (carbonyl and hydroxyl) in DT, but also preserved the unique electrode architecture with the required conductivity of the graphene nanosheets. In the three-electrode system, the optimized electrode (DT–RGNs 3 : 5) exhibited an excellent capacitance of 491 F g−1 at 1 A g−1 which is three times higher than that of bare RGNs. Most importantly, the DT–RGNs electrode showed an ultrahigh rate capability of 80.8% capacitance retention at 100 A g−1 and a superior electrochemical stability of 98.8% after 10 000 cycles at 10 A g−1, outstripping a great amount of reported organic and inorganic electrodes. Meanwhile, the effect of intramolecular and/or intermolecular hydrogen bonds between carbonyl and hydroxyl on the electrochemical properties of the DT–RGNs electrode was investigated. Finally, the novel symmetric supercapacitor (DT–RGNs SSC) was assembled to evaluate the actual energy storage properties of electrode materials. [ABSTRACT FROM AUTHOR]

A five-coordinate copper(II) complex with the tripod ligand tris(N-methylbenzimidazol-2-ylmethyl)amine (Mentb) and salicylate, with the composition [Cu(Mentb) (salicylate)](ClO4) · 2DMF, was synthesized and characterized by elemental and thermal analyses, electrical conductivity, IR and UV-Vis spectral measurements. The crystal structure of the complex has been determined by single-crystal X-ray diffraction. The Cu(II) is five-coordinate with four N atoms from the Mentb ligand and an O atom of the monodentate salicylate ligand. The N4O donors are in a distorted trigonal-bipyramid geometry. Cyclic voltammograms indicate a quasireversible Cu2+/Cu+ couple. The X-band EPR spectrum of the complex confirms the trigonal-bipyramidal structure with g∥ < g⊥ and a very small value of A∥ (41 × 10-4 cm-1). [ABSTRACT FROM AUTHOR]