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Based on their characteristics, transition metal layered double hydroxides have been of great scientific interest for their use in supercapacitors. Up until now, severe aggregation and low intrinsic conductivity have been the major hurdles for their application. In this work, nickel–iron sulfide nanosheets (NiFeSx) and carbon nanotubes (CNTs) were synthesized on diatomite using chemical vapor deposition and a two-step hydrothermal method to overcome these challenges. Synthesis of this composite successfully exploits the synergistic effect of multicomponent materials to improve the electrochemical performance. Diatomite is selected as a substrate to provide preferable surroundings for the uniform dispersion of nanomaterial on its surface, which enlarges the active sites that come in contact with the electrolytes, significantly improving the electrochemical properties. Combined with high conductivity and a synchronous sulfurization effect, the NiFeSx@CNTs@MnS@Diatomite electrode delivered a high specific capacitance of 552F g−1 at a current density of 1 A g−1, a good rate capability of 68.4% retention at 10 A g−1, and superior cycling stability of 89.8% capacitance retention after 5000 cycles at 5 A g−1. Furthermore, an asymmetric supercapacitor assembled via NiFeSx@CNTs@MnS@Diatomite and graphene delivered a maximum energy density of 28.9 Wh kg−1 and a maximum power density of 9375 W kg−1 at a potential of 1.5 V. This research lays the groundwork for ideal material preparation as well as a rational design for the electrode material, including property enhancement of diatomite-based material for use in supercapacitors.

Corrosion inhibitor microcapsules were prepared by centrifugation-coating method and the influence factors on the morphology of microcapsules were discussed. Process technology was optimized by orthogonal design method, with the rotational speed of turntable at 500 r/min, the fan speed at 400 r/min, the speed of peristaltic pump at 15 r/min and the jet pressure at 0.20 MPa. Analysis on the surface morphology, thermal stability and mechanical properties of microcapsules revealed that the obtained microcapsules had high drug loading rate and good mechanical strength, and higher weight gain rate of wall material can obtain thicker wall. Their release rates measured in the simulated concrete pore solution showed that microcapsules with higher weight gain rates had slower release rate, polymethyl methacrylate as wall material released faster than ethyl cellulose.

Magnesium alloys, the advanced lightweight structural materials, have been successfully applied in the manufacturing field. Unfortunately, their poor corrosion resistance restrains the potential wide applications. In this work, anti-corrosion coatings were fabricated via the in-situ growth of the corrosion inhibitors intercalated magnesium-aluminum layered double hydroxide (Mg–Al LDH) on AZ31 magnesium alloy and then post-sealing it by a super-hydrophobic coating. SEM, XRD, EDS, FTIR, XPS and contact angle test were conducted to analyze physical/chemical features of these coatings. Potentiodynamic polarization curves and electrochemical impedance spectroscopy were recorded to assess the anti-corrosion performance of prepared coatings. Surprisingly, Mg–Al LDH with molybdate intercalation and lauric acid modification achieves the excellent corrosion inhibition performance (99.99%) due to the multicomponent synergistic effect such as the physical protection of Mg–Al LDH, the corrosion inhibition of molybdate and super-hydrophobic properties of lauric acid. This work presents a scientific perspective and novel design philosophy to fabricate the efficient anti-corrosion coating to protect magnesium alloys and then expand their potential applications in other field. Keywords: Magnesium alloy, Superhydrophobicity, LDH films, Corrosion inhibitor, Corrosion resistance

Nowadays, energy and the environment have become critical issues for determining the sustainability of the Earth. Freshwater crises, as an increasingly serious global problem, pose a great threat to our economies, the environment and us. Solar-driven evaporation has emerged as a promising and sustainable approach to convert solar energy into clean water. In fact, the production of freshwater is not only governed by heat generation at the interface, but the process also relies on the coordination and cooperation of functional modules in the solar-driven evaporation system. This review begins with system designs of solar evaporators, considering thermal manipulation structures, water transportation pathways, and vapour condensation modules, which focus on improving the overall energy utilization, long-term usability, and freshwater yield. This is followed by a summary and discussions of cutting-edge solar evaporation applications and their underlying mechanisms. Finally, existing challenges and potential solutions for future applications are discussed and provided. This review aims to provide useful guidelines and references to scientists and researchers for the future development of clean water generation systems.

A calcium oxalate-mineralized film was synthesized in situ on the surface of Portland-cement-based material, aimed at protecting the concrete against water penetration and to facilitate crack repai...

The functionalization of graphene has been reported widely, showing special physical and chemical properties. However, due to the lack of surface functional groups, the poor dispersibility of graphene in solvents strongly limits its engineering applications. This paper develops a novel green “in-situ titania intercalation” method to prepare a highly dispersed graphene, which is enabled by the generation of the titania precursor between the layer of graphene at room temperature to yield titania-graphene nanocomposites (TiO2-RGO). The precursor of titania will produce amounts of nano titania between the graphene interlayers, which can effectively resist the interfacial van der Waals force of the interlamination in graphene for improved dispersion state. Such highly dispersed TiO2-RGO nanocomposites were used to modify epoxy resin. Surprisingly, significant enhancement of the mechanical performance of epoxy resin was observed when incorporating the titania-graphene nanocomposites, especially the improvements in tensile strength and elongation at break, with 75.54% and 176.61% increases at optimal usage compared to the pure epoxy, respectively. The approach presented herein is easy and economical for industry production, which can be potentially applied to the research of high mechanical property graphene/epoxy composite system.

Efforts to develop microcapsules that respond to different stimuli derive from the incorporation of multiple dynamic assemblies of diverse functional species to the capsule shells. However, this usually involves complicated preparation processes that ultimately hinder the integration of multiple functionalities in a single material. This is addressed in the present work by proposing a multilevel interfacial assembly approach involving polymeric complexes that facilitate the fabrication of multistimuli-responsive microcapsules based on one-step Pickering emulsification using oppositely charged polycation-graphene oxide (GO) and polyanion-surfactant complexes prepared in immiscible liquid solutions. The complexes initially stabilize the emulsion based on electrostatic interactions. Subsequently, the highly dynamic bonding between the polymeric complexes facilitates the rearrangement of components at the oil/water interface to form a continuous interfacial shell membrane. The integrity of the microcapsule shells is sensitive to near-infrared irradiation owing to the GO component and is also sensitive to NaCl content because the assemblies between nanoparticles and polyelectrolytes are bonded through electrostatic interactions. The generality of the proposed strategy is demonstrated by the interfacial assembly of polycation-Fe3O4 complexes and polyanion-surfactant complexes. The resulting microcapsules exhibit salt responsiveness, pH responsiveness, and the ability to be positioned controllably by the application of an external magnetic field. This work provides a promising approach for the preparation of multistimuli-responsive microcapsules.

Preparation of two-dimensional hybrid nanoarrays with porous structure and multiple active components is considered as an effective strategy to improve the electrochemical performance of supercapacitors. Herein, etched CoAl LDO/MnO2 was in-situ prepared on Ni foam by a simple hydrothermal process and subsequent alkali etching treatment. The morphologies and structures of synthetic nanocomposites were examined by XRD, SEM, TEM, EDS, BET and XPS. The nanocomposites present unique hybrid nanoarrays in which etched CoAl LDO nanoarrays form a core and worm-like MnO2 nanosheets create a shell. The electrochemical properties of etched CoAl LDO/MnO2 electrodes were examined by CV, CC and cycling tests. The results exhibit an excellent areal specific capacitance of 991 mF cm−2, desirable rate capability and outstanding cycling stability of 79.87% retention over 10000 cycles. The asymmetric supercapacitor using etched CoAl LDO/MnO2//AG achieves the maximum energy density and power density of 16.6 Wh kg−1 and 5000 W kg−1, respectively. The excellent electrochemical performance of the as-prepared material suggests its potential application for clean energy storage.

Cracking is a major form of failure in cementitious materials. In this study, the cracking process in a mortar is non-destructively investigated using an in-situ X-ray computed tomography (XCT) method. A novel image-processing method that allows for 3D visualization of the cracking process and for the distinction between pores and cracks is proposed to identify cracks inside concrete structures. With the proposed method, the fracture process in a mortar can be visualized, and quantitative information regarding the amount of solid, pores, and cracks inside the mortar can be obtained. Based on the experimental results, three fracture stages were observed: a compression stage, an expansion stage, and a cracking stage, which is consistent with the concrete compression failure process fracture theory.

Layered double hydroxides (LDHs) are attracting intense research interests as methyl orange (MO) adsorbent due to the unique anionic exchange ability. Herein, ultrasmall NiAl LDHs with Cl– intercal...

Mg-Al layered double hydroxides intercalated with nitrite ions was prepared by three different methods: calcined-rehydration (R-LDH), hydrothermal (H-LDH) and coprecipitation (C-LDH) method. The products were characterized and the results indicated that C-LDH had the highest intercalated rate of anions. The ion substitution test also verified C-LDH exhibited the largest adsorption capacity of chloridion. The inhibition efficiency and corrosion current density of C-LDH from electrochemical test both had the better performance than R-LDH and H-LDH over immersion time. Therefore, C-LDH could had the best anticorrosion in a long period and its mechanism of corrosion protection was also discussed.

Al-Based LDH materials have been considered as promising active electrode materials for pseudocapacitors due to their structural tunability. In this work, we employed a hydrothermal method, alkali etching treatment, calcination and sulfofication to achieve crystalline phase transformation. According to this pathway, five materials, including CoAl LDH, Co2AlO4, Co(OH)2, Co3O4 and Co4S3, have been prepared. The structural and physical/chemical properties are characterized by XRD, XPS, BET, SEM, TEM and FTIR. The electrochemical behaviors in supercapacitor and asymmetric supercapacitor (ASC) devices are characterized, respectively. As the electrode materials in supercapacitors, the specific capacitances are in the order CoAl LDH > Co4S3 > Co2AlO4 > Co3O4 > Co(OH)2. The CoAl LDH exhibits the maximum specific capacitance due to the intercalation/deintercalation of electrolyte ions which is attributed to its unique layer structure. The CoAl LDH exhibits a high specific capacitance of 983.71 F g−1 at 1 A g−1, a superior rate capability of 79.00% at 20 A g−1 and excellent cycling stability with a capacitance retention of 89.10% after 15 000 cycles. After assembling the ASC device, a maximum energy density of 16.275 W h kg−1 and a high power density of 3500 W kg−1 are achieved in a potential window of 1.4 V. In a word, the study not only provides a dependable pathway for materials modification, but also promotes the development of cobalt-based electrode materials for energy storage.

Rational design of the crystal structures of electrode materials is considered as an important strategy to construct high-performance supercapacitors. Herein, the three-dimensional crystal structure NiMn LDH@Co3O4 composites on Ni foam with different feeding Ni/Mn molar ratios were well-designed with hydrothermal, calcination and co-deposition methods, wherein urea hydrolysis supplied the alkali and carbonate ions. The electrochemical properties of the produced electrode materials were analyzed by cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), electrochemical impedance spectroscopy (EIS) and cycling stability tests using 6 M KOH electrolyte. Indeed, the optimal feeding Ni/Mn molar ratio was determined to be 3 : 1. The resulting electrodes exhibited maximum specific capacitance (607.9 F g−1 at 0.5 A g−1), respectable rate capability and excellent cycling stability with less than 3% loss of capacitance after 1000 cycles, which could be ascribed to the well-designed core–shell architecture and ultrathin nanosheets structure of LDH. As for practical application, the asymmetric supercapacitor assembled using NiMn LDH@Co3O4 as the positive electrode and activated graphene (AG) as the negative electrode was also evaluated, which demonstrated a high energy density of 26.49 W h kg−1 at the power density of 350 W kg−1. The findings suggest that the three-dimensional crystal structure NiMn LDH@Co3O4 composites have potential application as promising electrode materials for energy storage devices or other applications.

Three-dimensional (3D) nanocomposite (NC) printing has emerged as a major approach to translate nanomaterial physical properties to 3D geometries. However, 3D printing of conventional NCs with polymer matrix lacks control over nanomaterial connection that facilitates maximizing nanomaterial advantages. Thus, a printable NC that features nanomaterials matrix necessitates development, nevertheless, faces a challenge in preparation because of the trade-off between viscosity and interfacial stability. Here, we develop viscoelastic Pickering emulgels as NC inks through jamming nanomaterials on interfaces and in continuous phase. Emulgel composed of multiphases allow a vast range of composition options and superior printability. The excellent attributes initiate NC with spatial control over geometrics and functions through 3D printing of graphene oxide/phase-change materials emulgel, for instance. This versatile approach provides the means for architecting NCs with nanomaterial continuous phase whose performance does not constrain the vast array of available nanomaterials and allows for arbitrary hybridization and patterns., Nanocomposite (NC) printing emerged as a major approach to translate nanomaterial properties to 3D geometries but printing of conventional NCs lacks control over nanomaterial connection. Here, the authors develop viscoelastic Pickering emulgels as NC inks through jamming nanomaterials on interfaces and in continuous phase

Here, we report fabrication of two-dimensional (2D) lead monoxide (PbO) nanosheets by facile liquid phase exfoliation. The as-prepared 2D PbO nanosheets have circle and cut-circle shapes with a lat...

© 2018 Elsevier Ltd Actual dispersion of graphene oxide (GO) in cement paste was investigated by using both X-ray computed tomography and X-ray photoelectron spectroscopy. It was found that GO nanosheets are mainly agglomerated, as an individual phase, with platelet-like morphology and little GO being absorbed onto surfaces of cement particles and hydration products. By performing an electrical resistivity test, GO agglomerates are found to be more electrically insulative than cement paste. Therefore, it is not possible to develop self-sensing cement composites by incorporating GO directly without resolving its dispersion issue. However, GO agglomerates enhance the flexural strength of cement paste because of their special morphology and intrinsic strength. Results showed that the flexural strength of cement paste was increased by 83% with incorporation of 0.04% GO by weight of cement.

A novel type of microcapsule-based self-healing material which holds promise for crack-healing of concrete in a marine environment is designed and prepared, in which the calcium sulfoaluminate cement (CSA) is used as the healing agent. In the present work, X-ray microcomputed tomography (X-ray μCT) is innovatively applied to study the crack-healing process of the microcapsules based self-healing system. The healing mechanism is further analyzed by means of scanning electron microscopy (SEM)/energy-dispersive X-ray spectroscopy (EDS). The experimental results demonstrate that the microcapsule-based self-healing system is feasible and effective. The initial cracks are dramatically restored with the fill of the hydration product brought about by the CSA and water. The extent and rate of the self-healing process strongly depend on the transport of water from the surface to the body of the cementitious materials. The healing efficiency is up to 82.60% according to the volume variation of the cracks.

The recent surge in spectroscopic Single-Molecule Localization Microscopy (sSMLM) offers exciting new capabilities for combining single molecule imaging and spectroscopic analysis. Through the synergistic integration of super-resolution optical microscopy and single-molecule spectroscopy, sSMLM offers combined strengths from both fields. By capturing the full spectra of single molecule fluorescent emissions, sSMLM can distinguish minute spectroscopic variations from individual fluorescent molecules while preserving nanoscopic spatial localization precision. It can significantly extend the coding space for multi-molecule super-resolution imaging. Furthermore, it has the potential to detect spectroscopic variations in fluorescence emission associated with molecular interactions, which further enables probing local chemical and biochemical inhomogeneities of the nano-environments. In this review, we seek to explain the working principle of sSMLM technologies and the status of sSMLM techniques towards new super-resolution imaging applications.

An electrodeless resistivity method is applied to trace the early hydration behavior of magnesium potassium phosphate cement (MKPC). The relationship between setting times (including initial and final setting time) and the characteristic points of the electrodeless resistance is studied, aiming to establish a rapid testing method which could predict the setting time of MKPC. Moreover, a linear relationship between the standard compressive strength at 28 days and the resistivity at 24 h of MKPC is also established, and demonstrates that the resistivity and the standard compressive strength have a compact corresponding relationship. Therefore, the standard compressive strength of magnesium potassium phosphate cement could be predicted by electrodeless resistivity parameters.

A novel chemical self-healing system, with sodium monofluorophosphate/ethyl cellulose microcapsules, is designed with the objective of inhibiting rebar corrosion in concrete materials under NaCl solution. The corrosive behavior is traced and analyzed in 3D visualization by the method of micro X-ray computed microtomography (X-ray μCT). Environmental scanning electron microscopy (ESEM) and texture element analysis microscopy (TEAM) are used to verify the results from the X-ray μCT measurement. The experimental results show that typical pitting corrosion features are detected directly by X-ray μCT. The chemical self-healing system, with sodium monofluorophosphate/ethyl cellulose microcapsules, can postpone the rust procedure and effectively inhibit the rust rate of rebar in a simulated corrosion environment. The corrosion-inhibiting performance becomes significant with the microcapsules increasing. Moreover, a linear relationship between volume losses of rebar and time is deduced from the X-ray μCT data. Corresponding corrosion ratios and corrosion rates are quantitatively calculated for comparison of the inhibition afforded by the chemical self-healing system.

The chloride transport behavior of fly ash blended cement material was investigated in this study by using electrochemical impedance spectroscopy (EIS). The chloride penetration was studied by means of EIS. A new equivalent circuit model was applied to describe the electrochemical system of fly ash blended cementitious materials. Experimental results demonstrate that the increase in the fly ash replacement ratio of sample can increase the penetration depth of chloride ion. In addition, the increase in the fly ash replacement ratio of sample can enlarge the Nyquist curve semi-circle, and improve ion transfer resistance at the solid-liquid phase interface. We determined the quantitative relationship between electrochemical properties and chloride penetration depth in order to successfully predict the chloride ion penetration depth of blended cements with varying fly ash content. It is expected to complement the existing test standards regarding the durability evaluation of construction materials.

Two kinds of chemically-triggered self-healing systems with novel microcapsules are designed to protect rebar from corrosion in concrete. X-ray micro-computed tomography (XCT) method is employed to non-destructively visualize the protection performance and quantitatively evaluate the efficacy of the self-healing system in a wet-dry cyclic accelerating corrosion test. Environmental scanning electron microscopy (ESEM) system equipped with texture element analysis microscopy (TEAM) is used to verify the results of XCT imaging analysis. The results reveal that the self-healing system-high efficiency is achieved by delaying the depassivation of the rebar and reducing the corrosion rate.

Hierarchical three-dimensional (3D) porous structures of nickel–cobalt layered double hydroxide (LDH) are grown on diatomite biotemplate via one-step hydrothermal method. The crystal morphologies and properties of the materials can be controlled by adjusting the ratios of Ni–Co ions concentration during the reaction process. Increasing the proportion of nickel causes the morphology of the Ni–Co LDHs to change from nanowires to nanosheets, and improves the electrochemical performance of Ni–Co LDH@diatomite. The Ni3Co1 LDH@diatomite composites exhibit an ultrahigh specific capacitance of 514 F g−1 at a current density of 1 A g−1 and have 94.2% capacitance retention after 5000 cycling tests at a current density of 2 A g−1. Interestingly, the assembled Ni–Co LDH@diatomite@nickel foam//AG asymmetric supercapacitor (ASC) achieves a maximum energy density of 56 Wh kg−1 at a current density of 1 A g−1.

Herein, we synthesized Ca(OH)2 microcapsules with ion-responsive shells composed of cross-linked poly-ionic liquids (CPILs). By exchanging PF6− with Cl− in water, the hydrophobic poly-ionic liquids (PILs) on the shell are converted to hydrophilic channels. The encapsulated Ca(OH)2 can permeate through the hydrophilic channels and release OH−. Meanwhile, the Cl− content can be reduced. The release rate of Ca(OH)2 is influenced by the content of monomers and concentration of Cl− ions in water. SO42− can also trigger the release of Ca(OH)2 from the microcapsule. With these microcapsules, Q235 steel exhibited promising corrosion resistance in simulated seawater. These results indicate that encapsulation of corrosion inhibitors is highly desirable for enhanced corrosion resistance of steel bars and the proposed approach can be used to encapsulate various corrosion inhibitors and functional materials for a wide range of applications.

In order to improve the plasticity of composites, rubber is usually incorporated in cement composites, but the rubber greatly increases complexity in the analysis of internal structures. In this study, X-ray computed tomography (XCT) and digital volume correlation (DVC) were adopted to investigate the internal structure and volumetric strain of rubber−cement composites during fracture. The fracture process of the composites was tracked by in situ XCT loading tests by analyzing the extracted data of rubber particles and cracks. The internal volumetric strains of the samples with different rubber contents at different loading stages were calculated by DVC. The outcomes exhibit that the degree of dispersion of strain and the conductivity to force of samples were improved significantly with the increasing rubber contents.

The fire-resistance of carbonated concrete under high temperatures is significant due to its direct exposure during an accidental fire. To evaluate the carbonation effect on fire-resistance of concrete, the chemical and mineralogical changes of uncarbonated and carbonated cement pastes subjected to high temperatures were thoroughly investigated in this research by employing micro-measurement methods including thermal-gravimetric analysis (TGA), X-ray diffraction (XRD) and 29Si nuclear magnetic resonance (29Si NMR). Uncarbonated cement paste results showed the decomposition of portlandite at 400 °C with the formation of lime, whilst the depolymerization of C–S–H happened simultaneously to generate monomeric silicon tetrahedron. Above 720 °C, all the C–S–H depolymerized to crystalline C2S. Carbonated cement pastes on the other hand showed that amorphous calcium carbonate and part of vaterite decomposed between the range of 400–600 °C, while the rest of the vaterite and calcite were decomposed at 600–720 °C. The individual content of calcium carbonate polymorph could not be obtained using a TGA curve. Besides, the calcium-modified silicate gel was significantly decomposed at 500 °C and completely depolymerized to crystalline C2S at 950 °C. In summary, carbonated pastes show better resistance to high temperatures with its heat absorption capacity 3.3 times as high as the uncarbonated sample, which delays the temperature development in the inner layer. Therefore, a reasonable carbonation process could help to improve the fire resistance of concrete to some extent.

Two-dimensional (2D) monoelemental bismuth (Bi) crystal, one of the pnictogens (group VA), has recently attracted increasing interest because of its intriguing characteristics. Here, uniformly sized 2D Bi quantum dots (BiQDs) with an average diameter (thickness) of 4.9 ± 1.0 nm (2.6 ± 0.7 nm) were fabricated through a facile liquid-phase exfoliation (LPE) method, and the corresponding photoresponse was evaluated using photoelectrochemical (PEC) measurements. The as-fabricated BiQDs-based photodetector not only exhibits an appropriate capacity for self-driven broadband photoresponse but also shows high-performance photoresponse under low bias potentials ranging from UV to visible light in association with long-term stability of the ON/OFF switching behavior. In terms of these findings, it is further anticipated that the resultant BiQDs possess promising potential in UV–visible photodetection as well as in liquid optoelectronics. Our work may open a new avenue for delivering high-quality monoelemental pnict...

Polymer/metal hydroxide microcapsules with sustained-release property were prepared by centrifuge coating granulation method in order to stabilize pH value of concrete for protecting steel bar in concrete. Effects of microcapsules characteristics on the release rate of metal hydroxide in the solution simulating concrete pores were studied by thermo gravimetric analysis (TGA) and the stabilization effect of metal hydroxide microcapsules on the pH value of concrete were also discussed. The results revealed that the microcapsules with higher weight gain rate of wall material during fluidized bed coating processing had the slower release rate of core material. Moreover, the release rate of polymethyl methacrylate (PMMA) microcapsule was faster than that of ethyl cellulose (EC) microcapsule. Metal hydroxide microcapsules could delay the decline of pH value, especially PMMA microcapsules with 20% weight gain rate. In addition, metal hydroxide microcapsules could improve the pH values of actual concrete blocks and had better effect than those directly added in concrete. Surface corrosion morphology of steel bars immersed in the simulated solution showed that microcapsules could effectively retard the corrosion rate of steel bars, and the anticorrosion effect became better with the increase of microcapsules dosage.

Microcapsules composed of polylactic acid (PLA)/corrosion inhibitor sodium monofluorophosphate (MFP) were prepared by spray drying, and the effects of processing parameters on the morphology and encapsulation efficiency of the microcapsules were investigated. The results showed that low viscous PLA solution only resulted in porous microcapsules with low encapsulation efficiency, whereas filamentous substances were produced instead of microcapsules once PLA solution content exceeded 5%. When spray pressure exceeded 0.4 MPa, the microcapsule surface was wrinkled due to high evaporation rate of the atomized droplets. The spray pressure less than 0.3 MPa created larger atomized droplets and yielded the adhesive microcapsules with lower encapsulation efficiency. The optimal emulsion parameters were as follows: PLA concentration, 5%; water-oil ratio, 1:9; inlet air temperature, 50 °C; and spray pressure, 0.4 MPa. The resulting microcapsules exhibited a good sustained-release behavior in a simulated concrete pore solution.

Two styrene-acrylate (SA) polymer latexes with and without the introduction of PEO hairy layer on the surface of colloidal particles were synthesized. The impacts of the latexes on setting time and cement hydration were evaluated. The hydrolysis of acrylate contained in the polymers and the complexation ability of the generated carboxyl group with Ca2+ were investigated. It is found hairy layer of colloidal particles minimizes the retardation effect on cement hydration, although it does not mitigate the acrylate hydrolysis and the complexation effect of generated carboxyl groups. Hairy surface reduces the adsorption of polymer on cement surface and consequently leads to less retardation effect on cement hydration.

There is a higher demand for the resistance of chloride ion of the buildings in coastal environment. In this paper, glass flake was used to improve the mechanical properties and chloride ion permeability resistance of epoxy emulsion cement mortar. The effects of polymer/cement ratio (P/C), glass flake content (glass flake/cement ratio) and size of glass flake on the properties of modified mortar were studied. The results indicated that glass flake could simultaneously improve the mechanical properties and chloride ion permeability resistance of epoxy emulsion cement mortar. The flexural strength of modified mortar was improved by 20.4% by incorporation of 120 mesh glass flake. More significantly, water absorption and chloride diffusion coefficient of modified mortar reduced by 39.8% and 48.2%, respectively. The morphology of samples observed by scanning electron microscopy (SEM) confirmed the effect of bridging connection and barrier action of glass flake on epoxy emulsion cement mortar.

X-ray microcomputed tomography (X-ray μCT) method is proposed to trace steel corrosion and corrosion-induced cracking in cement paste. Experimental results show it can track the time-dependent development of steel corrosion and corrosion products, as well as the subsequent initiation and propagation of corrosion-induced cracks. Furthermore, the information of corrosion pits, corrosion products, and corrosion-induced cracks can be clearly obtained from the whole specimen by this novel method. Additionally, SEM/EDS results agree closely with image analyses by X-ray μCT. This method provides a new angle to investigate the reinforcement corrosion process and can help to improve the numerical analysis of corrosion-induced damage in reinforced concrete structures.

This paper aims to use electrochemical impedance spectroscopy (EIS) with a novel equivalent circuit (EC) model to examine the hydration behavior of cement materials that incorporate ground granulated blast furnace slag. The experimental results suggest that the electrochemical impedance behavior of blended cement materials vary depending on the slag content. Also, the resistance associated with the ion transport process increases gradually along with the hydration process, and decreases as the slag is incorporated into the cement. In addition, we describe the linear relationship between the R ct1 value and the compressive strength for different slag contents and curing ages. The proposed method of EIS for slag blended cement materials, and the reliability of the new equivalent circuit model, is investigated across the entire hydration process of slag blended cement materials. Finally, the correlation of the compressive strength and the R ct1 value of blended cement materials with different slag contents are analyzed.

A research work is carried out to understand the influence of slag incorporation on the electrochemical behavior of carbonated cement systems. Measurement of carbonation depth and electrochemical impedance spectroscopy is conducted. A suitable equivalent circuit model is applied to fit the measured electrochemical impedance data (Nyquist curve) and quantitatively obtain the electrochemical property for carbonated slag blended cement. Test results demonstrate that increasing the slag replacement ratio in cement can increase the carbonation depth, enlarge the semi-circle of the Nyquist curve, and improve the resistance of ion transfer at the “solid-liquid phase” interface. We also compare the slag incorporation effect on the electrochemical system of carbonated cement with another common mineral admixture (i.e. fly ash). It is found that slag blended cement exhibits smaller semi-circle of Nyquist curve and larger carbonation depth than fly ash blended cement. Based on the electrochemical modification, we also predict the carbonation depth of blended cements with different slag contents.

Semiconductor nanocrystals and their variants are widely used in biological research as fluorescent probes. Their unique characteristics, such as intense brightness, tunable emission properties, and resistance to photobleaching, make them ideal candidates for single-molecule imaging and tracking with localization precision far beyond the diffraction limit. Their fluorescence polarization states and emission spectra can be further utilized to probe changes in their mechanical properties and residing nanoenvironments. We developed a three-dimensional (3D), polarization-sensitive, spectroscopic photon localization microscopy (3D-Polar-SPLM) that enables parallel 3D tracking of individual quantum rods (QRs) while simultaneously capturing their fluorescence spectra and polarization states. Using 3D-Polar-SPLM, we spatially localized individual QRs with a lateral localization precision of 8 nm and an axial localization precision of 35 nm. In addition, we achieved a spectral resolution of 2 nm and a polarization...

This paper presents work toward the development of self-healing materials that hold promise for permeability healing of concrete or other cementitious composites. To achieve this innovative system, Urea-formaldehyde/Epoxy microcapsule was designed and synthesized by an in-situ polymerization method, using epoxy resin E-51 as the curing agent and urea-formaldehyde resin as the shell material. The viability of microcapsule and the influence of microcapsules on mechanical properties of specimens were investigated first. The breakage of microcapsules upon cracking and the crack-healing results were verified by SEM/EDS. Self-healing capacity was evaluated by crack-healing effect and chloride permeability. The experimental results shown that the chloride diffusion coefficient decreased from 8.15 to 6.53 ( × 10−12 m2 s−1) after 28-day healing. The healing efficiency of permeability increased to a maximum level of 19.8%. It was also noticed that several factors such as the amount of microcapsules, particle size, healing age, curing temperature and pre-load level have great influences on the self-healing efficiency.

A new method for periodically monitoring reinforcement corrosion in concrete with Ground-Penetrating Radar (GPR) is proposed and a ten-year long-term corrosion periodic monitoring experiment is reported. GPR historical data was taken in different years, under different conditions. In order to align and normalize the obtained images properly prior to effectively performing any automatic defect detection, image registration techniques based on mutual-information are employed, and a new signal processing scheme is proposed for normalizing the intensity of GPR images. Then, the processed image results can be used to compare and find out the change of GPR detection due to corrosion.

Iridium oxide pH electrodes employing the carbonate melt oxidation method were fabricated with oxidation temperatures of 750 &deg, C, 800 &deg, C and 850 &deg, C, respectively. Scanning electron microscope (SEM) and atomic force microscope (AFM) images showed that the oxide film regularized with the increase in oxidation temperatures. The pH response, response time and long-term stability of the electrodes indicated that the electrodes made at 850 &deg, C had the best performance. X-ray photoelectron spectra (XPS) surveys investigated the change in the electrodes&rsquo, chemical composition and element oxidation states at 850 &deg, C, and the results showed that the relative content of Ir3+ had increased by 23.9%, and the Ir4+ and Ir6+ had decreased by 10.9% and 13%, respectively, in the surface oxide layer after one month of aging. However, the relative contents of Ir3+, Ir4+ and Ir6+ were almost constant for the inner oxide layer. Meanwhile, the XPS result also indicated that the outer oxide layer of the electrode had a higher hydration degree than the inner oxide layer.

Corrosion is a challenging problem for marine concrete infrastructure projects. In this study, an intelligent OH&minus, regulated microcapsule is designed to prevent reinforcement corrosion, taking ethylcellulose (EC) as shell material and calcium oxide (CaO) as core material. X-ray computed tomography (XCT) is used to trace and contrast the corrosion profiles of the concrete reinforcement bar with and without the microcapsule. The results show that the OH&minus, regulated microcapsule exhibits effective corrosion protection by delaying corrosion initiation and cracking. An SEM study revealed that the microcapsule could be broken as Cl&minus, invades the concrete. However, intelligent OH&minus, regulation was realized by releasing CaO.

Controlled release of hydrophobic agents from salt-responsive capsules is hindered by the hydrophilic shell and interfacial tension between inner oil and surrounding water. Rupturing shells in salt solution is another effective way. However, the densely entangled polyelectrolytes (PEs) in shells determined that the rupture requires extremely high ion-strength. Herein, salt-responsive capsules with double-network shells including a continuous PE-nanocrystal network and interfacial ion pairs are proposed and revealed via a one-step interfacial multilevel and multicomponent assembly (IMMA) method. Rigid nanocrystals can weaken the entanglements of PE chains and reduce the critical salt-concentration. Interfacial ion pairs are responsible for maintaining the stability of the shells. Such double networks enable the disintegration of capsules in an applicable salt-concentration without damaging the stability of capsules. In addition, hydrophobic domains assemblied by surfactants and PE-nanocrystal network supply transport pathway for oil to across hydrophilic shells and subsequently produce inverse micelle to carry oil into water. The mechanism of formation and release of capsules is systematically investigated, which further demonstrates IMMA to be a typical method for creation of sophisticated structures in a brief way.

Microring resonator (MRR) ultrasound detectors provide orders of magnitude greater sensitivity and frequency range (to < 10 Pa, from DC to 100 s of MHz) than previously achieved in recording acoustic emissions from materials at high pressures. We characterize acoustic emissions from crystal-structural phase transitions in Si to pressures of 50 GPa, well beyond the brittle-ductile transition at room temperature, and find that the number of events increases nearly tenfold for each decade reduction in the duration of recorded events. The shortest-duration events arrive in clusters, suggestive of a self-propagating, transformation-catalyzed process.

In this study, the ultra-thin CoAl layered double hydroxide (LDH) nanosheets with Cl− intercalation were prepared by a hydrothermal method following acid-salt treatment. The morphology, structure and composition information of CoAl LDHs were identified by a variety of characterization methods including SEM, XRD, XPS, FT-IR, and BET. The effects of initial adsorbent concentration, pH, competitive anions, and temperature were also measured. The fitted adsorption curves are matched well with Langmuir isotherm model and pseudo-second-order kinetic model, suggesting that the removal of methyl orange (MO) is governed by monolayer heterogeneous adsorption and chemical adsorption, respectively. The measurements of adsorption capacity at various temperatures revealed that the adsorption process is spontaneous. Co-existing anions have different negative effects on the adsorption capacity. The Co4Al1-Cl LDH adsorbent shows the maximum experimental and theoretical adsorption capacity of 801.08 and 827.50 mg g−1 (pH = 7 and T = 293 K), respectively. An adsorption mechanism called “ion exchange and expansion-extrusion” is proposed to explain the change of interlayer spacing. These results indicate that a novel avenue for designing LDH-type adsorbent has been proposed with excellent adsorption capacity for anionic dyes like MO.

Emulsion droplet assemblies have evolved dramatically in recent years due to their hierarchical structure and advanced performance. However, studies into their structural stability in strong acid/alkali aqueous environments and geometry reshaping of these assemblies are rare. Herein, novel emulsion droplet assemblies with Ag nanocrystals (Ag NCs) as “binding agents” are fabricated via a facile method combining Ag+ coordination and photoreduction. Due to the strong binding effect of the Ag NCs and their high chemical inertness against acids and bases, the resulting assemblies exhibit a remarkable acid/alkali resistance, which makes them distinct from previous emulsion droplet assemblies. Benefiting from the chloride corrosion and photothermal conversion features of Ag NCs, the resulting assemblies manifest a slow chloride ion response and fast NIR response. In addition, these assemblies can be easily processed into various shapes that can be further sculpted into more complex geometries through a combination of localized photoreduction and anion etching, which demonstrates the reshaping ability of the assemblies and allows the assemblies to adapt to a variety of spatial structure requirements in applications. This is the first work that acid/alkali-resistant and geometry reshaping of emulsion droplet assemblies have been addressed. As emulsion droplets show excellent potential as building blocks for assemblies, our findings offer new paradigms for the development and application of assemblies.

The transition metal phosphides have been gradually used in supercapacitors due to its excellent conductivity and electrochemical activity. In this work, the novel composite CoP@NiCoP directly grown on Ni foam was prepared by a facial two-steps hydrothermal and one-step phosphorization method. The CoP nanowires serve as the skeleton and conductive pathway for NiCoP nanosheets and the active material involved in electrochemical process to provide extra capacitance. With the skeleton of CoP nanowires, NiCoP nanosheets have more sites to anchor and can transfer electrons quickly. Taking advantage of structure and transition phosphides, the CoP@NiCoP possesses a superior specific capacitance of 1911.6 F g−1 (265.5 mAh g−1) at 2 A g−1, outstanding rate performance with 61.68% retention even at 25 A g−1 and good cycling stability with 73.3% capacitance retention after 1000 cycles at 25 A g−1. In addition, an asymmetric supercapacitor (ASC) consisted by CoP@NiCoP and the Fe2O3 derived from Fe-based MOF delivers a satisfactory energy density of 37.16 Wh kg−1 at the corresponding power density of 875 W kg−1. The excellent electrochemical performance verifies the effectiveness of the composite structure and transition phosphides and thus provide a novel strategy for the further design of high performance supercapacitors.

This paper describes a study on using embedded cement-based piezoelectric ceramic sensors to detect crack propagation in mortar specimens under cubic-splitting load by acoustic emission (AE). The main objective is to characterize the fracture process in mortar specimen in the cubic-splitting test. AE sensors (piezoelectric composites as core elements, and a mixture of cement, epoxy resin and hardener as packaging material) can be embedded into concrete and still have broadband frequency response and good matching ability with the cement material. The three-dimensional localization of the AE sources, signal-based AE energy index and variation characteristics of the AE frequency content were used to explain and quantitatively evaluate the fracture processes of the mortar specimens. The results show that the fracture processes in the mortar under the cubic-splitting are evidently brittle fracture and the variation behaviors of the AE frequency content, which exhibited a close relationship with the applied loading processes during the tests. It was also found that the application of cement-based piezoelectric ceramic sensors by means of AE represents a good option to analyze the crack growth in the specimens under increasing load, the location of the cracks and, in addition, it offers the potential for in-situ application.

Influences of styrene-acrylate (SA) latexes on cement hydration were investigated by isothermal calorimetry and the mechanism wasdiscussed. Super-retardation phenomenon caused by addition of SA latexes on oil well cement hydration was found at 80 °C by setting time measurement. Quantitative analysis of hydrolysis of SA latexes in cementitious systems and their effect on cement hydration were investigated by FTIR, zeta potential and surface charge density measurements. Results show that the hydrolysis of ester groups in acrylate units is significantly accelerated by elevated temperature in alkaline condition. The continuous production of carboxyl groups promotes the adsorption of polymer particles on the surface of cement grains and/or leads to continuous Ca 2+ sequestration from pore solution. These two aspects are the causes of the super-retardation effect. It is concluded that unless special chemistry is involved in the preparation of SA latexes, such as construction of core-shell structure of the colloidal particles, SA latexes with high content of acrylate units, due to the severe hydrolysis of the ester groups in the polymer chains, are not recommended to be used in oil well cement system.

In this paper, a kind of novel ethyl cellulose (EC)/calcium hydroxide microcapsule to establish a self-immunity system based on increasing hydroxyl content for the reinforced concrete is proposed. The capacity for lifting the threshold value of [Cl − ]/[OH − ] in this system is feasibly evaluated. Different dosages of microcapsules are placed in the sodium chloride solution with a concentration of 3.5 wt% to characterize the corrosion protection by means of linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). The working mechanism of this system consists of the chemical triggering (capsule shell) and releasing (capsule core) processes when a microcapsule is exposed a decreasing pH condition, and the release of core materials in turn restores the alkaline environment against steel bar depassivation. The test results of environmental scanning electron microscopy (ESEM) equipped with texture element analysis microscopy (TEAM) reveal that the capsule shell sensible to the [Cl − ]/[OH − ] ratio forms an excellent low-pH trigger mechanism. In addition, the electrochemical experiment indicates the chloride-induced corrosion intensity of a steel bar can be monitored with the decreasing I corr and more negative E corr , which is further observed by the pitting characteristics of steel bars.

Artificial polariton bandgaps at infrared frequencies are investigated by exploiting the strong coupling of electromagnetic waves with induced electric dipoles in two-dimensional (2D) indium tin oxide nanorod arrays (ITO-NRAs). The electric dipoles originate from the collective oscillations of free electrons within the individual ITO nanorods undergoing plasmonic resonance. Controlling the near-field interactions among the neighboring electric dipoles allows for manipulation of the collective polariton modes that are manifested as a polariton bandgap. A theoretical model is developed to understand the coupled phenomena underlying the unique characteristics of plasmon–polariton bandgaps. With high-degree geometric control of the ITO-NRAs, it is experimentally demonstrated that reducing the spacing between ITO nanorods in a square array strengthens the near-field interactions and thus results in a redshift as well as broadening of the polariton bandgap. Furthermore, arranging ITO-NRAs in a rectangular lattice breaks the symmetry with respect to the principle axis, which leads to a splitting of the collective polariton modes owing to the competition between the quasi-longitudinally and quasi-transversely coupled plasmon–polariton modes. The work highlights the use of a classical dipole coupling method for scaling polariton bandgaps to the infrared in artificial plasmonic lattices, thereby offering a new design dimension for infrared sensing, absorbers, and optical communications.

Visualizing the nanoscale intracellular structures formed by nucleic acids, such as chromatin, in nonperturbed, structurally and dynamically complex cellular systems, will help expand our understanding of biological processes and open the next frontier for biological discovery. Traditional superresolution techniques to visualize subdiffractional macromolecular structures formed by nucleic acids require exogenous labels that may perturb cell function and change the very molecular processes they intend to study, especially at the extremely high label densities required for superresolution. However, despite tremendous interest and demonstrated need, label-free optical superresolution imaging of nucleotide topology under native nonperturbing conditions has never been possible. Here we investigate a photoswitching process of native nucleotides and present the demonstration of subdiffraction-resolution imaging of cellular structures using intrinsic contrast from unmodified DNA based on the principle of single-molecule photon localization microscopy (PLM). Using DNA-PLM, we achieved nanoscopic imaging of interphase nuclei and mitotic chromosomes, allowing a quantitative analysis of the DNA occupancy level and a subdiffractional analysis of the chromosomal organization. This study may pave a new way for label-free superresolution nanoscopic imaging of macromolecular structures with nucleotide topologies and could contribute to the development of new DNA-based contrast agents for superresolution imaging.

This paper proposes a novel approach to achieve self-healing property of cement sheath in the oil well triggered by oil leakage through cracks. An oil swellable polymer (OSP) with oil absorptivity as high as 700% was synthesized through emulsion polymerization. The OSP dispersion was added into the Portland cement paste. It is found that the oil absorption and the linear expansion of the OSP modified hardened cement paste (MHCP) are greatly increased compared to the blank hardened cement paste (BHCP). Pore structure measurements by N 2 adsorption show that the addition of OSP decreases the total porosity of MHCP which confirms that the formation of the polymeric film in MHCP. The self-healing ability of MHCP was evaluated by the oil flow test through a single crack in the cylindrical specimen. The oil flow tests indicate that the leakage of oil through the crack is gradually mitigated due to the expansion of the MHCP and thus the self-healing ability is successfully achieved.