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Utilizing activated sludge as a partial substitute for cement can both curb cement consumption and address sludge reuse in an economically and environmentally-friendly manner. This study delves into the pozzolanic activity of mechanically-thermal (MT) activated sludge and alkali-mechanical-thermal (AMT) activated sludge, employing the strength activity index (SAI) method. Microscopic insights provided by X-ray diffraction (XRD), scanning electron microscopy (SEM), and laser particle size analysis aid in the interpretation of observed phenomena. The findings underscore the superiority of MT activation over AMT activation, with an SAI of 97 %. Optimal pozzolanic activity is achieved through a 2-hours holding time, slow heating at 10 °C/min, and rapid cooling. A calcination temperature of 800 °C effectively promotes the decomposition of active minerals and enhances the sludge's pozzolanic activity. Additionally, a ball milling time of 2 minutes proves sufficient to meet practical demands, as prolonged ball milling has a limited impact on sludge pozzolanic activity.

The use of cement-based conductive mortar is an effective way to enhance the long-term operation of impressed current cathodic protection (ICCP) system. However, its widespread use is limited by the challenges of dispersing nano-fillers and the associated cost. To overcome these challenges, this study proposes the use of expanded graphite (EG) as a conductive material due to its strong conductivity, easy dispersion, and low cost. Additionally, multilayer EG flakes can promote cement hydration due to their high specific surface area, thereby improving the mechanical properties of mortar. This study examines the effects of EG content on the mechanical properties and electrical conductivity of the conductive mortar. Results reveal an exponential relation between EG content and mechanical strength, with 1.5% EG content producing the maximum mechanical properties. The resistivity of EG cement mortar decreases as the EG content increases, reaching its minimum at the percolation threshold. At this threshold, the resistivity of conductive mortar is 46.4% of the optimal content for mechanical properties (EG content is 1.5%). The incorporation of EG in cement-based conductive mortar is a viable alternative to traditional materials that can improve both conductivity and mechanical properties. This approach has great potential for enhancing the performance of ICCP systems.

This study investigated effects of crystalline admixture (CA) on shrinkage and alkali-silica reaction behaviours of biochar-cementitious composites. Addition of 1–1.5 wt% superabsorbent polymer (SAP) completely mitigated autogenous shrinkage while slightly increasing the 120-day total shrinkage of the SP-cement composite by 5.7%, resulting in the highest apparent porosity. 1–1.5 wt% CA addition did not affect autogenous shrinkage while slightly reducing the 120-day total shrinkage by 10.1%. The combination of CA and waste wood biochar (WWB) reduced autogenous shrinkage by 24.23% and 120-day total shrinkage by 23.6%, resulting in the lowest apparent porosity. The formation of hydration products in the WWB pores and on WWB surface densified the cementitious matrix, leading to a reduction in water evaporation. Furthermore, for specimens exposed to 1 M NaOH solution at 80 °C, CA addition significantly reduced the 120-day expansion by 50.6%, while the combination of CA and WWB addition reduced the 120-day expansion by 42.9%.

Due to a loose and porous structure, the addition of sintered sludge ash (SSA) in large amounts often leads to a decrease in durability. To address the issue, a systematic investigation is conducted into the combined effects of seawater and SSA (0∼50%) on cement paste. The mixing of seawater enhances the improvement effect of 10% SSA on frost resistance and capillary water absorption. Meanwhile, the seawater-mixed cement paste containing 30% SSA withstands 125 freeze-thaw cycles, superior to PC. After seawater mixing, SSA performs better in terms of the generation of high-density C–S–H gel. The promoting effect of SSA on the transformation of capillary pores into gel pores in cement paste and its content threshold are amplified. The chemical binding of Cl− and SO42− with amorphous Al2O3 in SSA promotes the conversion of AFt to AFm. Additionally, based on multi-criteria analysis, the seawater-mixed sintered sludge cement is more competitive.

Magnesium phosphate cement (MPC) is a promising material known for its rapid hardening and high early-strength properties. However, its potential in engineering applications is hindered by its harden at an uncontrolled rate, considerable volumetric distortion and poor water resistance. To address the limitations, this study investigates the influence of sintered sludge ash (SSA) modification on the setting time, volume deformation, mechanical strength and water resistance of MPC composites. Experimental reveals that the setting time of MPC composites increase with higher SSA content, and the inclusion of SSA significantly mitigate volumetric deformation. Moreover, the mechanical strength exhibits improvement at all ages, and combine with water resistance analysis, 15% SSA content is the optimal level. Based on the XRD, TG, MIP and SEM, the enhanced properties of the MPC composites may be attributed to the reaction of SSA in the MPC system, leading to the resulting aluminum-containing gel phase acting as a binder along with guano to densify the microstructure.

The proposal of sintered sludge cement (SSC) paste aligns with the low-carbon development goals of building materials. However, there is a lack of scientific guidance for the preparation of sintered sludge ash (SSA). Herein, this study systematically investigates the influence mechanism of mechanical–thermal activation parameters of SSA on the mechanical properties and life cycle assessment (LCA) of SSC paste, and conducts a comprehensive evaluation using a radar chart and the TOPSIS method. The results show that with the increase in calcination temperature and duration, the compressive and flexural strengths of the SSC paste are improved, especially at 600 °C and above, increasing by 57.92% and 62.52%, respectively. The longer calcination time at 1000 °C results in a decrease in its mechanical properties. The addition of SSA significantly reduces the LCA indicators of cement paste. Specifically, 30% SSA only contributes 8.1% to the global warming potential. Compared to calcination, the LCA indicators have less sensitivity to ball milling, and prolonging the time hardly increases them. Based on performance and environmental impact, the optimal SSA is obtained by calcining at 800 °C for 2 h and ball milling for 10 min. This study can provide theoretical guidance for efficient building material utilization of dredged sludge.

This study investigated the carbonaluminate cementitious materials (i.e., sodium aluminate (NaAlO2)-activated limestone pastes) with gradient calcite (CaCO3)/NaAlO2 molar ratios ranging from 1:1 to 6:1 (samples M1 to M6). NaAlO2 dosage affected the reaction process, hydration product, and cementitious property of the formed pastes. The thermonatrite (Na2CO3·H2O) and AH3 phase as hydration products exist in all the samples. Microcrystalline AH3 phase (crystallite size is near 22 nm) held a superior cementitious property, which was evidenced by diffraction spots scattered on concentric rings in transmission electron microscopy (TEM) results. Other hydrates varied with the CaCO3/NaAlO2 ratio. In case of lower CaCO3/NaAlO2 ratio (i.e., M1), NaAlO2 was incompletely consumed. The residual NaAlO2 promoted the formation of cubic-shaped katoite (3CaO·Al2O3·6H2O). Such hydrate barely contributed to the cementitious property of the formed matrix. When the CaCO3/NaAlO2 ratio reached 1.5:1 (e.g., M1.5-M6), NaAlO2 was entirely consumed, and monocarboaluminate (Mc, 3CaO·Al2O3·CaCO3·11H2O) instead of katoite was preferentially generated. The amounts of total hydrates decreased with the increasing CaCO3/NaAlO2 ratio, leading to the degraded properties of formed matrix. Thus, the 28-day compressive strength of M1.5 was the highest among these samples, reaching 35.55 MPa.

Molybdenum tailings (MT) are solid waste from molybdenum ore beneficiation, which can cause environmental pollution when stored in tailings ponds for a long time. The use of alkaline hydrothermal activation to improve the low reactivity of MT as an active precursor to one-part geopolymers is a novel way to resource MT. This paper evaluates the feasibility of alkaline hydrothermal activation of MT and investigates the mechanical properties of the activated MT base polymer prepared by a one-part method. The results showed that alkaline hydrothermal activation greatly promoted the dissolution of silicon in MT, weakened the crystal properties of quartz phase in MT and destroyed the original structure of MT. The amorphous sodium aluminosilicate on the surface of activated MT dissolves in water and provides an alkaline environment for the geological polymerization reaction. Combined with the analytical results of XRD and FTIR, the alkaline hydrothermal activation of MT was controlled by the optimal sodium hydroxide solution concentration, activation temperature and activation time of 5 M NaOH, 200 °C and 4 h, respectively. Based on this, the one-part geopolymer was prepared directly by adding water to activated MT 5-4-200 and slag, and the compressive strength can be improved. SEM and EDS results show that alkaline hydrothermal activation treatment renders inert MT reactive and the reaction product of activated MT and slag forming a one-part geopolymer is an amorphous C(N)A-S-H gel.

In this work, a new strategy to improve the ability of protective layer against wave scouring damage in the splash zone is proposed by developing a protective layer based on triboelectric nanogenerator (TENG). TENGs endow the protective layer with the wave energy harvest ability during wave scouring the concrete structure. The harvesting process, facilitated by the elastic deformation of TENG, mitigates the impact of ocean waves on both protective layer and the concrete. Importantly, this process concurrently generates electrical energy, subsequently utilized to support a cathodic protection system, thereby providing an additional layer of defense for the rebar. A systematical investigation into the performance of the self-charging protective layer is conducted, revealing crucial insights and design guidelines for the implementation of this self-charging protective layer. The self-driven cathodic protection system proves highly effective in safeguarding the rebar, including a substantial drop in the open current potential (OCP) of rebar from − 584 mV (vs. SCE) to − 1121 mV (vs. SCE). Based on this protective layer, a protection system from concrete surface to rebar was constructed, inspiring a comprehensive way to prevent ion diffusion and inhibit rebar erosion for concrete protection.

Abstract Due to the excellent biocompatible physicochemical performance, luminogens with aggregation-induced emission (AIEgens) characteristics have played a significant role in biomedical fluorescence imaging recently. However, screening AIEgens for special applications takes a lot of time and efforts by using conventional chemical synthesis route. Fortunately, artificial intelligence techniques that could predict the properties of AIEgen molecules would be helpful and valuable for novel AIEgens design and synthesis. In this work, we applied machine learning (ML) techniques to screen AIEgens with expected excitation and emission wavelength for biomedical deep fluorescence imaging. First, a database of various AIEgens collected from the literature was established. Then, by extracting key features using molecular descriptors and training various state-of-the-art ML models, a multi-modal molecular descriptors strategy has been proposed to extract the structure-property relationships of AIEgens and predict molecular absorption and emission wavelength peaks. Compared to the first principles calculations, the proposed strategy provided greater accuracy at a lower computational cost. Finally, three newly predicted AIEgens with desired absorption and emission wavelength peaks were synthesized successfully and applied for cellular fluorescence imaging and deep penetration imaging. All the results were consistent successfully with our expectations, which demonstrated the above ML has a great potential for screening AIEgens with suitable wavelengths, which could boost the design and development of novel organic fluorescent materials.

Abstract Accurate plantar pressure mapping systems with low dependence on the external power supply are highly desired for preventative healthcare and medical diagnosis. Herein, we propose a self‐powered smart insole system that can perform both static and dynamic plantar pressure mapping with high accuracy. The smart insole system integrates an insole‐shaped sensing unit, a multi‐channel data acquisition board, and a data storage module. The smart insole consists of a 44‐pixel sensor array based on triboelectric nanogenerators (TENGs) to transduce pressure to the electrical signal. By optimizing the sensor architecture and the system's robustness, the smart insole achieves high sensitivity, good error‐tolerance capability, excellent durability, and short response–recovery time. Various gait and mobility patterns, such as standing, introversion/extraversion, throwing, and surpassing obstacles, can be distinguished by analyzing the acquired electrical signals. This work paves the way for self‐powered wearable devices for gait monitoring, which might enable a new modality of medical diagnosis.

Triboelectric nanogenerators (TENGs) can harvest various forms of mechanical energy from the surrounding environment and convert them into electrical energy efficiently. Harvesting wind energy from the environment by TENG could be an ideal way to achieve self-powered sensing systems. Herein, a novel calliopsis-inspired biomimetic TENG (C-TENG) was designed for harvesting wind energy and a self-powered wind-parameter sensor. The open-circuit voltage (Voc) and short-circuit current (Isc) of one unit C-TENG can reach 61.7 V and 0.34μA under a wind speed of 15 m/s at a frequency of 5 Hz, and the peak output power is 11.57 mW/m2 under a load resistance of 100 MΩ. This not only collects wind energy effectively but also could be utilized to detect wind speed and direction as a self-powered wind sensor. In this study, we demonstrate a novel type of contact-separation mode TENG in calliopsis structure for wind energy harvesting and promote novel self-powered wind sensors for meteorological monitoring, agricultural production, and the nautical industry.

Abstract Chemo-photothermal therapy based on nanoparticles has emerged as a promising strategy for cancer treatment. However, its therapeutic efficacy and application potential are largely subjected to the uncontrollability and biotoxicity of functional nanoplatforms. Herein, a novel biocompatible and biodegradable metal organic framework (MOF), which was constructed by growing crystalline zeolitic imidazolate framework-8 on gold nanoroad (Au@ZIF-8), was designed and fabricated for efficient drug loading and controlled release. Owing to the large surface area and guest-matching pore size of ZIF-8, doxorubicin (DOX) was successfully loaded into the Au@ZIF-8 with a high drug loading efficiency of ~ 37%. Under NIR light or weakly acidic environment, the ZIF-8 layer was quickly degraded, which resulted in an on-demand drug release in tumour site. More importantly, under the irradiation of near infrared (NIR) laser, highly efficient cancer treatment was achieved in both in vitro cell experiment and in vivo tumour-bearing nude mice experiment due to the synergistic effect of photothermal (PTT) therapy and chemotherapy. In addition, the in vivo study revealed the good biocompatibility of Au@ZIF-8. This work robustly suggested that Au@ZIF-8 could be further explored as a drug delivery system for chemo-photothermal synergistic therapy.

Layered double hydroxide (LDH), a kind of 2D layered materials, has been recognized as the promising anticorrosion materials for metal and its alloy. The microstructure, physical/chemical properties, usage in corrosion inhibition and inhibition performance of LDH have been studied separately in open literature. However, there is a lack of a complete review to summarize the status of LDH technology and the potential R&D opportunities in the field of corrosion inhibition. In addition, the challenges for LDH in corrosion inhibition of metal-based system have not been summarized systematically. Herein, we review recent advances in the rational design of LDH for corrosion inhibition of metal-based system (i.e. Mg alloy, Al alloy, steel and concrete) and high-throughput anticorrosion materials development. By evaluating the physical/chemical properties, usage in metal-based system and the corrosion inhibition mechanism of LDH, we highlight several important factors of LDH for anticorrosion performance and common features of LDH in applying different metal alloys. Finally, we provide our perspective and recommendation in this field, including high-throughput techiniques for combinatorial compositional design and rapid synthesis of anticorrosion alloys, with the goal of accelerating the development and application of LDH in corrosion inhibition of metal-based system.

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

Abstract Lamellar inorganic fillers have been used to improve the performance of polymer composites. In this paper, five kinds of lamellar inorganic fillers, including montmorillonite (MMT), mica, talc, glass flake (GF) and lamellar double hydroxide (LDH), were selected to modify epoxy emulsion cement mortar (EECM). The research evaluated the effects of the structure characteristics of lamellar fillers on the mechanical properties, water absorption and chloride ion permeability resistance of EECM, with comparison to granular ground calcium carbonate (GCC). Results indicated that lamellar fillers had no obvious superiority than GCC in the mechanical strength of EECM, even MMT caused the decline of the mechanical strength. However, lamellar fillers had improved the chloride ion permeability resistance of EECM compared with GCC, and they had the similar effect on reducing of water absorption except MMT. Although the low aspect ratio (AR) of the lamellar fillers benefited the increase of the strength and water resistance of EECM, the lamellar fillers with higher AR could improve the chloride ion permeability resistance of EECM more efficiently.

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

Extramammary Paget’s disease (EMPD) is a rare, malignant cutaneous adenocarcinoma with a high recurrence rate after surgical resection. Early diagnosis of EMPD is critical as 15%–40% of cases progress into an invasive form and resulting in a dismal prognosis. However, EMPD can be a diagnostic challenge to pathologists, especially in the grassroots hospital, because of its low incidence and nonspecific clinical presentation. Although AI-enabled computer-aided diagnosis solutions have been extensively used in dermatological pathological image analysis to diagnose common skin cancers such as melanoma and basal cell carcinoma, these techniques have yet been applied to diagnose EMPD. Here, we developed and verified a deep learning method with five different deep convolutional neural networks, named ResNet34, ResNet50, MobileNetV2, GoogLeNet, and VGG16, in Asian EMPD pathological image screening to distinguish between Paget’s and normal cells. We further demonstrated that the results of the proposed method are quantitative, fast, and repeatable by a retrospective single-center study. The ResNet34 model achieved the best performance with an accuracy of 95.522% in pathological images collected at a magnification of ×40. We envision this method can potentially empower grassroots pathologists’ efficiency and accuracy as well as to ultimately provide better patient care.

The microstructure and performance of magnesium potassium phosphate cement (MKPC), a kind of magnesium phosphate cement (MPC), are determined by the hydration products. In this paper, the hydration behavior of MKPC is investigated through various material characterization methods and thermodynamic modeling, including X-ray diffraction (XRD), thermogravimetric and differential scanning calorimeter (TG/DSC), scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP) and GEMS software. The results of XRD, TG/DSC and SEM all indicate that K-struvite (MgKPO4·6H2O) is the main hydration product of MKPC. When the curing age is 1 day and 28 days, the TG data indicate that the mass loss of MKPC in the range of 60–200 °C is 17.76% and 17.82%, respectively. The MIP results show that the porosity of MKPC is 29.63% and 29.61% at the curing age of 1 day and 28 days, respectively, which indicates that the structure of MKPC becomes denser with the increase in curing age. In addition, the cumulative pore volume of MKPC at the curing age of 28 days is 2.8% lower than that at 1 day, and the pore diameters are shifted toward the small pores. Furthermore, the thermodynamic modeling is well suited to make an analysis of the hydration behavior of MKPC.

Chronic cranial windows (CCW) enable long-term imaging of brain activity, but usually they only provide passive optical access to the tissue. Here the authors develop an active CCW integrated with an ultrasound detector which enables long-term photoacoustic imaging of the cortical vasculature in live mice with higher image quality.

Due to the easily controllable interlayer anions, metal cation composition proportion and thickness, which is beneficial to modify surface chemical state and tune bandgap, layered double hydroxides (LDHs) have great promising potential for photocatalytic applications. In this study, we have successfully synthesized the ZnAl–LDH intercalated the single anion between ZnAl cationic interlayer without anionic impurities by using a facile calcining and reconstructing routes. The electron structure and surface chemical state of the prepared products have been investigated by combining the DFT calculation and experimental characterization methods. UV–vis DRS was used to certify the light absorption of the prepared products, and we performed the DFT calculation to demonstrate the density of state and activation of reactant. These results suggested that the ZnAl–LDH–CO3 possessed the more proper band structure and superior ability to activate NO and O2 for accelerating the photocatalytic NO oxidation activity. Moreover, the in situ DRIFTS with dynamically monitoring intermediates and products over the ZnAl–LDH–CO3 was adopted to declare the photocatalytic NO oxidized process during the photocatalytic reaction process. This work illustrated the influence of different interlayer anions to the electron structure and surface chemical state of ZnAl–LDH structure through the experimental verification combined DFT calculation and the photocatalytic NO oxidized process via in situ DRIFTS analyzing, which would provide a novel way to design and fabricate the efficient photocatalysis, and understand the reaction process. Keywords: Photocatalytic NO oxidation, ZnAl–LDH, Reaction process and mechanism, In situ DRIFTS, DFT calculation

Blood glucose concentration is important for metabolic homeostasis in humans and animals. Many diabetic patients need to detect blood glucose daily which burdens community hospitals and family healthcare. Optical fiber sensors are widely used in biomedical detection because of their compact structure, fast response, high sensitivity, low cost, and ease of operation. In this work, we constructed a Fabry-Perot (FP) cavity biosensor for the fast detection of glucose concentration in serum. The femtosecond laser micromachining was applied to fabricate the FP cavity by printing the fiber-tip fixed-supported bridge at the end face of the optical fiber. An additional hemisphere was printed at the center of the outer surface of the bridge to avoid multi-beam interference. The results demonstrated that the proposed biosensor had high refractive index (RI) detection sensitivity, roughly 1039 nm/RIU at a wavelength of 1590 nm, and the detection sensitivity for glucose was around 0.185 nm/ (mg/mL) at a wavelength of 1590 nm. Due to its high sensitivity, compact structure, and fast response, the FP cavity biosensor has great potential to be applied in family healthcare for glucose concentration detection of diabetic patients.

In the interest of solving the resource and environmental problems of the construction industry, low-carbon geopolymer coating ensures great durability and extends the service life of existing infrastructure. This paper presents a multidisciplinary assessment of the protective performance and environmental impacts of geopolymer coating. Various parameters, such as main substance, water-solid (W/S) ratio, activator type and curing time, were investigated for their effects on interface characterization in terms of contact angle, surface energy, mechanical properties and microstructure. These parameters had negligible effects on the amounts and types of hydrophilic functional groups of geopolymer surfaces. A combination of organic surface modifiers and geopolymer coatings was shown to ensure hydrophobic surface conditions and great durability. Silicon-based modifiers exhibited better wetting performance than capillary crystalline surfactants by eliminating hydroxyl groups and maintaining structural backbone Si-O-T (Si, Al) on geopolymers’ surfaces. Finally, life-cycle analysis was conducted to investigate the environmental performance. Geopolymer coating yielded substantially lower environmental impacts (50–80% lower in most impact categories) than ordinary Portland cement (OPC) coating. Silicon-based modifiers had negligible influence due to their minimal usage. Increasing the W/S ratio diluted the geopolymer coating and decreased the environmental impacts, and slag-based geopolymer coating achieved lower environmental impacts than FA-based and MK-based varietie.

Graphene oxide (GO) has been found to be an attractive nanomaterial to improve the properties of cementitious composites. However, the use of GO in the industry is limited by its high cost. To achieve a higher cost/performance ratio, GO can be strategically applied in certain parts of cementitious composites structure according to the principle of functionally graded materials. In this study, graded distribution of GO in cement mortar was achieved by sequentially casting a fresh GO-incorporated cement layer on another cement mortar layer. The mechanical properties, especially flexural strength, of layered cement mortar were found to be dependent on the GO content, the delay time, and the interface formed due to layering fabrication. With the GO incorporated in the tensile region only (30% of the total depth), the flexural strength of the layered beam attained 90.91% of that of the beam, with GO uniformly distributed throughout the sample. Based on the results of rapid chloride migration tests, when 12 mm GO-incorporated cement mortar layer was used, the chloride migration coefficient was reduced by 21.45%. It was also found that the measured chloride migration coefficient of layered cement mortar agreed with the series model. The present investigation provides an efficient approach to use GO in cement-based materials from the perspective of mechanical and durability properties.

Abstract Despite their seemingly random appearances in the real space, quasi-random nanophotonic structures exhibit distinct structural correlations and have been widely utilized for effective photon management. However, current design approaches mainly rely on the deterministic representations consisting two-dimensional (2D) discretized patterns in the real space. They fail to capture the inherent non-deterministic characteristic of the quasi-random structures and inevitably result in a large design dimensionality. Here, we report a new design approach that employs the one-dimensional (1D) spectral density function (SDF) as the unique representation of non-deterministic quasi-random structures in the Fourier space with greatly reduced design dimensionality. One 1D SDF representation can be used to generate infinite sets of real space structures in 2D with equally optimized performance, which was further validated experimentally using light-trapping structures in a thin film absorber as a model system. The optimized non-deterministic quasi-random nanostructures improve the broadband absorption by 225% over the unpatterned cell.

Photon localization microscopy uses stochastic emission events from fluorescent molecules to enable super-resolution imaging, but spectroscopic information is lost. Here, the authors improve the spatial resolution of this technique with a method that also detects each blink’s fluorescence spectrum.

Calcium carbide residue (CCR) is a waste by-product from acetylene gas production. The main component of CCR is Ca(OH)2, which can react with siliceous materials through pozzolanic reactions, resulting in a product similar to those obtained from the cement hydration process. Thus, it is possible to use CCR as a substitute for Portland cement in concrete. In this research, we synthesized CCR and silica fume through a chemical combustion technique to produce a new reactive cementitious powder (RCP). The properties of paste and mortar in fresh and hardened states (setting time, shrinkage, and compressive strength) with 5% cement replacement by RCP were evaluated. The hydration of RCP and OPC (Ordinary Portland Cement) pastes was also examined through SEM (scanning electron microscope). Test results showed that in comparison to control OPC mix, the hydration products for the RCP mix took longer to formulate. The initial and final setting times were prolonged, while the drying shrinkage was significantly reduced. The compressive strength at the age of 45 days for RCP mortar mix was found to be higher than that of OPC mortar and OPC mortar with silica fume mix by 10% and 8%, respectively. Therefore, the synthesized RCP was proved to be a sustainable active cementitious powder for the strength enhanced of building materials, which will result in the diversion of significant quantities of this by-product from landfills.

In this research, structural-functional integrated cement-based materials were prepared by employing cement paste and a microencapsulated phase change material (MPCM) manufactured using urea-formaldehyde resin as the shell and paraffin as the core material. The encapsulation ratio of the MPCM could reach up to 91.21 wt%. Thermal energy storage cement pastes (TESCPs) incorporated with different MPCM contents (5%, 10%, 15%, 20% and 25% by weight of cement) were developed, and their thermal and mechanical properties were studied. The results showed that the total energy storage capacity of the hardened cement specimens with MPCM increased by up to 3.9-times compared with that of the control cement paste. The thermal conductivity at different temperature levels (35–36 °C, 55–56 °C and 72–74 °C) decreased with the increase of MPCM content, and the decrease was the highest when the temperature level was 55–56 °C. Moreover, the compressive strength, flexural strength and density of hardened cement paste decreased with the increase in MPCM content linearly. Among the evaluated properties, the compressive strength of TESCPs had a larger and faster degradation with the increase of MPCM content.

A new electrochemical model has been carefully established to explain the carbonation behavior of cement mortar, and the model has been validated by the experimental results. In fact, it is shown by this study that the electrochemical impedance behavior of mortars varies in the process of carbonation. With the cement/sand ratio reduced, the carbonation rate reveals more remarkable. The carbonation process can be quantitatively accessed by a parameter, which can be obtained by means of the electrochemical impedance spectroscopy (EIS)-based electrochemical model. It has been found that the parameter is a function of carbonation depth and of carbonation time. Thereby, prediction of carbonation depth can be achieved.

In this paper, concrete specimens are immersed in ultrapure water, to study the evolutions of surface permeability, pore structure and paste microstructure following the prolonging of immersion period. According to the results, after 30-day immersion, the surface permeability of concrete becomes higher as compared with the value before immersion. However, further immersion makes the surface permeability decrease, so that the value measured after 150-day immersion is only half that measured after 30-day immersion. The early increase in surface permeability should be mainly attributed to the leaching of calcium hydroxide, while the later decrease to the refinement of pore structure due to hydration. The two effects work simultaneously and compete throughout the immersion period. The proposed mechanisms get support from microscopic measurements and observations.

Iridium oxide pH electrodes employing the carbonate melt oxidation method were fabricated with oxidation temperatures of 750 °C, 800 °C and 850 °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 °C had the best performance. X-ray photoelectron spectra (XPS) surveys investigated the change in the electrodes’ chemical composition and element oxidation states at 850 °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.