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Poor crack resistance, high brittleness, and poor toughness are inherent limitations of traditional cement-based materials. Besides, cement-based materials have certain shortcomings in energy consumption and environmental protection. Therefore, improving the performance of cement-based materials becomes a hot topic in related research. At the same time, the development of nanomaterials and technologies provides researchers with a new research idea: to enhance the performance of cement-based materials at the nanoscale level. Graphene oxide (GO) is one of the most representative nano-reinforcements. Due to its high surface area and excellent physical properties, GO has a surprising effect on improving the performance of cement-based materials. In addition, nanosilica (NS) and carbon nanotubes (CNTs) have excellent improvement on cement-based materials, and people also hope to further improve the performance of cement-based materials through the interaction of various nanomaterials. In this paper, the influence of GO on cement-based materials is reviewed by consulting a lot of correlative literature, mainly focusing on the following aspects: (i) The dispersion of GO in cement paste. (ii) The influence of GO on the properties of cement-based materials, including working performance, mechanical strength, microstructural characteristics, and durability. (iii) The effect of nanohybrid materials of GO, NS, and CNTs on cement-based materials, and the synergistic effects of various nanomaterials are reviewed for the first time. (iv) Evaluation of current progress. This paper aims to provide guidance for the study and application of GO-modified cement-based materials and nanohybrid materials.

In this paper, the mechanical behavior of gradient nano-grained copper under uniaxial deformation was investigated using molecular dynamics simulations. The stress response was found to be different in the regions with different grain sizes, which was attributed to the different dislocation activities due to the dislocation-grain boundary synergies. The phenomenon of grain rotation was observed and a program was developed to accurately evaluate the grain rotation and explore its dependence on the grain size and the initial crystal orientation. It is found that all grains tend to rotate to the 30° orientation, consistent with the activation theory of the slip systems under the uniaxial deformation. The rotation magnitude is larger for larger grains, but the rotation rate is more diversely distributed for smaller grains, indicating more disturbance from grain boundary mechanisms such as the grain boundary sliding and the grain boundary diffusion for smaller grains. The effect of temperature on the grain rotation is also investigated, showing an increase of the dispersion of grain rotation distribution with the increase of temperature. This paper aims at providing insights into the synergistic deformation mechanisms from dislocations and grain boundaries accounting for the exceptional ductility of the gradient nano-grained metals.

Buildings contribute to 40% of total global energy consumption, which is responsible to 38% of greenhouse gas emissions. It is critical to enhance the energy efficiency of buildings to mitigate global warming. In the last decade, advances in thermal energy storage (TES) techniques using phase change material (PCM) have gained much attention among researchers, mainly to reduce energy consumption and to promote the use of renewable energy sources such as solar energy. PCM technology is one of the most promising technologies available for the development of high performance and energy-efficient buildings and, therefore, considered as one of the most effective and on-going fields of research. The main limitation of PCM is its leakage problem which limits its potential use in building construction and other applications such as TES and textiles, which can be overcome by employing nano-/micro-encapsulation technologies. This paper comprehensively overviews the nano-/micro-encapsulation technologies, which are mainly classified into three categories including physical, physiochemical and chemical methods, and the properties of microcapsules prepared. Among all encapsulation technologies available, the chemical method is commonly used since it offers the best technological approach in terms of encapsulation efficiency and better structural integrity of core material. There is a need to develop a method for the synthesis of nano-encapsulated PCMs to achieve enhanced structural stability and better fracture resistance and, thus, longer service life. The accumulated database of properties/performance of PCMs and synthesised nano-/micro-capsules from various techniques presented in the paper should serve as the most useful information for the production of nano-/micro-capsules with desirable characteristics for building construction application and further innovation of PCM technology.

The nanoscratch test has been identified as one of the important tools for evaluating the mechanical and tribological properties of materials. This paper reviews the current researches on the nanoscratch test using to characterise the mechanical properties of three typical materials, including thin film, polymer composite and concrete, from the perspectives of the Berkovich indenter, parameter selection, mode selection, and analysis of resulting data. In addition, to provide a deep understanding on the test from different magnitude, a comparison between the microscratch test and nanoscratch test on the evaluation of tribological performance is also provided in this paper. The characterisation by nanoscratch test of two structural samples, in terms of layered film structures (thin film and coating sample) and single layer block structure (polymer composite sample and concrete samples) are also described in this paper, which aims to provides a deep understand on the evaluation the adhesion, tribological and interfacial properties of the typical materials samples by nanoscratch test. Finally, the coefficient of friction and critical load are discussed, which are two important parameters in tribological properties and adhesion properties.

Experimental research on circular nano-silica concrete filled stainless steel tube (C-CFSST) stub columns after being exposed to freezing and thawing is carried out in this paper. All of forty specimens were tested in this paper, including nine C-CFSST specimens at normal temperature, 28 short columns of C-CFSST for freeze-thaw treatment and three circular hollow stainless steel stub columns. The failure mode, load-displacement curves, load-strain curves and load-bearing capacity were obtained and analyzed in this paper. The main parameters explored in the test include the number of freeze-thaw cycles (N=0, N=50, N=75, and N=100), wall thickness (T=1.0mm, T=1.2mm, T=1.5mm) andnano-silica concrete strength (fc=20MPa, fc=30MPa, fc=40MPa). The result shows that C-CFSST short columns at normal temperature and subjected to freezing and thawing follow similar failure mode. The effect of freeze-thaw cycles (N) of 50 on bearing capacity of C-CFSST column was maximal, and then the influence of Non the bearing capacity of specimens was small when Nreached to 75, finally the effect of Non bearing capacity of C-CFSST column was large when Nreached to 100. The bearing capacity of C-CFSST columns increases with increasing wall thickness. In addition, the loss percentage of bearing capacity of specimens (fc=40MPa) for freeze-thaw treatment is maximal, and the loss percentage of bearing capacity of specimens (fc=30MPa) for freeze-thaw treatment is minimal. According to the test results, this paper proposed a formula to calculate the bearing capacity of C-CFSST short columns for freeze-thaw treatment.

The QAnon conspiracy theory holds that former President Trump is fighting a ‘deep-state’ cabal of Satan-worshipping, cannibalistic pedophiles running a global child sex-trafficking ring. Conspirators include liberal Hollywood actors, Democratic politicians, financial elites, and even some religious leaders. Prominent politicians have embraced it, and the media increasingly covered it in the lead-up to the 2020 Presidential Election and beyond. Beginning on 4chan message boards in October 2017, QAnon narratives proliferated across popular social media platforms as individuals engaged in QAnon-related conversations on one platform shared links to ‘reputable’ content on others. In this paper, we draw on insights drawn from studies of diffusion and use social network analysis to analyze the networks generated by Twitter users from sharing external QAnon-related social media content via URLs during two key time frames: (1) the peak of QAnon Twitter activity in the Spring of 2020 and (2) the period following Twitter's crackdown on QAnon activities in July 2020. Our analysis reveals that the tweets and retweets of just a few actors accounted for most of the sharing of links to external social media sites, suggesting that other users saw them as reliable sources of information. It also shows that Twitter's crackdown impacted some aspects of the URL-sharing network. We conclude by briefly considering strategies for countering conspiracy theories and offering suggestions for future research.

In this paper, we reviewed the recent advances in nanoscale modifications and evaluated their potential for dental implant applications. Surfaces at the nanoscale provide remarkable features that can be exploited to enhance biological activities. Herein, titanium and its alloys are considered as the main materials due to their background as Ti-based implants, which have been yielding satisfactory results over long-term periods. At first, we discussed the survivability and the general parameters that have high impacts on implant failure and the necessities of nanoscale modification. Afterward, fabrication techniques that can generate nanostructures on the endosseous implant body are categorized as mechanical, chemical, and physical methods. These techniques are followed by biomimetic nanotopographies (e.g., nanopillars, nanoblades, etc.) and their biological mechanisms. Alongside the nanopatterns, the applications of nanoparticles (NPs) including metals, ceramics, polymers, etc., as biofunctional coating or delivery systems are fully explained. Finally, the biophysiochemical impacts of these modifications are discussed as essential parameters for a dental implant to provide satisfactory information for future endeavors.

Two-dimensional (2D) nanomaterial-reinforced polymer composites exhibit superior properties and multifunctional applications. Compared to lower dimensional nanomaterials such as nanotubes and nanoparticles, 2D nanomaterials show a larger surface area. The large surface area makes 2D nanomaterials more effectively restrict the mobility of polymer chains and yields better reinforcing efficiency than the lower-dimensional nanomaterials. To gain an in-depth understanding and extend the applications of polymer composites reinforced with 2D nanomaterials, this paper reviews the progress in the fundamentals of synthesis and applications of such composites. The motivation and improvement of adding 2D nanomaterials to polymer materials are introduced first, followed by the synthesis approaches and the properties of typical 2D nanomaterials, including graphene, boron nitride nanosheet, and molybdenum disulfide nanosheet. Based on the properties of 2D nanomaterials, polymer composites reinforced with different types of 2D nanomaterials are designed for structural application, thermal dissipation application, tribological application, three-dimensional printing composite structures, and strain sensing application. Afterwards, the significance of reinforcement–matrix interaction and its improving approach are reviewed. The current progress envisions that polymer composites reinforced with 2D nanomaterials can be used in the fields of aviation and aerospace for improving radiation shielding capacity and nanomedical engineering.

In this paper, the chain structure of magnetorheological fluid (MRF) magnetic particles was studied and analyzed, the mechanical model of MRF with different diameter ferromagnetic particles was established, silicone oil-based MRF with different particle volume fractions was prepared, the shear properties of the MRF were tested, and the theoretical and experimental data were compared. The experimental results show that the shear stress is stable with the increase of shear strain rate under the action of the magnetic field, and it has a shear thinning effect. The shear stress increases linearly with the increase of particle volume fraction. The shear stress increases with the increase of magnetic induction intensity. After data analysis and in the case of control variables, the average error of improved theoretical data and experimental data is lower than that of previous theoretical data and experimental data, which verifies that the improved theory (mechanical model) has a certain accuracy.

This paper takes nano-SiCp/Al–7Si matrix composites prepared by powder metallurgy as the research object. With the help of advanced microstructure characterization techniques and performance analysis methods, the effect of nano-SiCp volume fraction on the microstructure and properties of composites is systematically studied. Based on optimizing the volume fraction of nano-SiCp, the thermal deformation behavior of the composites is investigated. It was found that with an increase of nano-SiCp content, the distribution uniformity of nano-SiCp decreases gradually. And because the surface of nano-SiCp is easy to adsorb gas and the aggregated distribution of nano-SiCp is not conducive to the sintering process, the density of the composites shows a gradually decreasing trend. The hardness of the composites tends increasing gradually, and the increase in amplitude gradually decreases. Due to the addition of nano-SiCp, there are many interfaces between SiCp and Al matrix, and cracks are prone to initiation and expansion at the interface. Therefore, as the volume fraction of nano-SiCp increases, the elongation of nano-SiCp/Al–7Si composites gradually decreases. When the volume fraction of nano-SiCp is 2%, the strength of the composites reaches the maximum value of 217 MPa. Compared with the Al–Si alloy without adding nano-SiCp, the results increased by 37.3%. In addition, with the decrease of strain rate and the increase of deformation temperature, the dislocation density in the composites gradually decreases, and the dynamic softening progresses more fully. The dynamic recrystallization nucleation mechanism mainly includes the subcrystal merging mechanism and the grain boundary bowing mechanism.

Nano calcium silicate hydrate (nano-C–S–H) has become a novel additive for advanced cement-based materials. In this paper, the effect of nano-C–S–H on the early-age performance of cement paste has been studied, and some micro-characterization methods were used to measure the microstructure of nano-C–S–H-modified cement-based material. The results showed that the initial fluidity of cement paste was improved after addition of nano-C–S–H, but the fluidity gradual loss increased with the dosage of nano-C–S–H. The autogenous shrinkage of cement paste can be reduced by up to 42% maximum at an appropriate addition of nano-C–S–H. The mechanical property of cement paste was enhanced noticeably after adding nano-C–S–H, namely, the compressive strengths were improved by 52% and 47.74% at age of 1 day and 7 days, respectively. More hydration products were observed and pore diameter of cement matrix was refined after adding nano-C–S–H, indicating that the early hydration process of cement was accelerated by nano-C–S–H. This was mainly attributed to seed effect of nano-C–S–H. The detailed relationship between microstructure and early-age performance was also discussed.

The goals of this paper are to study the frost resistance of steel slag concrete (SSC), research the damage mechanisms, and predict the service life of SSC in cold regions. First, the stability of steel slag (SS) was tested, and then SS samples with different treatment dosages were used as aggregates to replace natural aggregates of equal volumes in the preparation of C40 concrete. The microstructures of concrete and micro properties of cement hydration products were investigated in nanospace in this research. In addition, rapid frost resistance durability tests were carried out under laboratory conditions. The results revealed that the ordinary concrete (OC) exhibited a more serious damage phenomenon, and the mass loss and relative dynamic elastic modulus of OC were changed by 5.27 and 62.30%, respectively. However, with increases in the SS content, the losses in mass were lowered. Furthermore, the relative dynamic elastic modulus decreased less, and the frost resistance of the specimens was stronger. The range of mass loss rate was between 2.233 and 3.024%, and the relative dynamic elastic modulus range was between 74.92 and 91.09%. A quadratic function with a good fitting degree was selected to establish a freezing-thawing damage calculation model by taking the relative dynamic elastic modulus as the variable. Then, the freezing-thawing durability lifespan of concrete in the colder regions of northern China was successfully predicted by using the damage calculation model. The results of SSC20–60showed the better frost resistance durability when the content of SS sand was 20% and the dosage of SS stone was 60%. Its frost resistance lifespan was more than twice that of OC, which demonstrated that SS as an aggregate could effectively improve the frost resistance lifespan of concrete to a certain extent.

This review is intended to provide an overview of the design and fabrication of ionic liquid-based ionic electroactive polymer (IL-iEAP) transducers for advanced applications in biological and electronic fields. The iEAP is a class of smart materials that can perform sensing or actuating functions by controlling the movement of cations and anions in the active layer. This type of material can deform under low voltage stimulation and generate electrical signals when undergoing mechanical deformation because of ion redistribution. Numerous research attention has been focused on studying the deformation mechanisms and the potential for actuation, sensing, and energy harvesting applications. Compared to the traditional water-based iEAP, the non-volatile IL-iEAP delivers a wider electrochemical window and a more stable actuation performance. In this paper, the classification of iEAP with different actuation mechanisms is first outlined, followed by introducing various preparation methods including nanotechnology for IL-iEAPs, and discussing the key factors governing their actuation performance. In addition, the advanced functions of IL-iEAP in actuating and sensing, especially self-sensing in bionics and electromechanical equipment applications, are reviewed. Finally, novel nanotechnologies used for fabricating IL-iEAPs and the prospects of their microelectromechanical system (MEMS) applications are discussed.

The raw materials of geopolymer come from industrial wastes, which have the advantages of lower carbon emissions and less energy consumption compared with traditional cement products. However, it still has the disadvantages of low strength, easy cracking, and low production efficiency, which limit its engineering application and development. At present, with the application and development of nanotechnology in the field of materials, it is found that nanomaterials have a good filling effect on composites, which greatly improves the integrity of the composites. It has become a very popular research direction to optimize and improve the engineering application performance of geopolymer concrete (GPC) by nanomaterials. The modification of nanomaterials can further improve the properties of GPC and expand its application fields in engineering and life. Based on people’s strong interest in nanomaterial-modified GPC and providing the latest and complete research status for further related work, this paper summarized the key technical problems in the field of nanomaterials-modified GPC in the past decade. Those include the modification mechanism, dispersion mode, and mechanical properties of nanomaterials. At the same time, the application bottlenecks and key problems of nanomaterials-modified GPC are comprehensively analyzed. Finally, the prospects and challenges of future work in this field are discussed.

In this paper, we use a simple and cheap approach for the synthesis of herceptin-conjugated graphene biosensor to detect the HER2-positive breast cancer cells. The bifunctional graphene-herceptin nanosheets are prepared from graphite by a simple ultrasonic-mediated technique. The prepared protein-mediated graphene is fully characterized. The results show the exfoliation of graphene layers in herceptin solution. Moreover, herceptin is effectively conjugated into the surface of graphene nanosheets. The synthesized herceptin-conjugated graphene is applied for breast cancer detection. The linear range of this biosensor is 1–80 cells, which is significant. The biosensor shows an excellent selectivity performance for detection of HER2-positive cancer cells. Likewise, the stability and functionality of the biosensor is about 40 days. Based on the results, this device is a promising candidate for rapid and selective detection of cancer cells.

Nano molding technology (NMT) has shown great potential in the preparation of metal/resin composites, which can integrate resin and metal into a lightweight, high-strength metal matrix composite. However, due to the poor interfacial bonding strength between metal and polymer, the application of the metal/polymer composites is limited. In this paper, we proposed a novel method to improve the bonding strength between Fe–Co–Ni alloy and epoxy resin by Nano Perfusion Technology (NPT), featuring in situgrowth of carbon nanotubes (CNTs) in the pores on anodized Fe–Co–Ni alloy porous surface, followed by a perfusion of epoxy resin throughout the pores that had been in situgrown CNTs. Due to the “anchor effect” of CNTs, the bonding strength between the epoxy and the alloy matrix is improved. The results showed that the interfacial bonding between the in situCNTs-modified alloy and the resin was significantly improved compared to the metal-resin composites surface treated with T-treatment in traditional method of NMT. The maximum interfacial bonding force of the alloy-CNTs/epoxy composite reached up to 691.80 N, which was 460, 315, and 267% higher than those by mechanical treatment, without CNTs and T-treatment, respectively. This work provides a new approach to protect metals or alloys from environmental corrosion, impact damage, and so on.

AbstractCritical-sized bone defects have, in many cases, posed challenges to the current gold standard treatments. Bioactive glasses are reported to be able to stimulate more bone regeneration than other bioactive ceramics; however, the difficulty in producing porous scaffolds made of bioactive glasses has limited their extensive use in bone regeneration. On the other hand, calcium phosphate ceramics such as synthetic hydroxyapatite and tricalcium phosphate are widely used in the clinic, but they stimulate less bone regeneration. This paper gives an overview of the recent developments in the field of bioactive nanoparticles, with a focus on nanohydroxyapatite and bioactive glasses for bone repair and regeneration. First, a brief overview of the chemical structure and common methods used to produce synthetic nanohydroxyapatite and bioactive glasses has been presented. The main body of the paper covers the physical and biological properties of these biomaterials, as well as their composites with biodegradable polymers used in bone regeneration. A summary of existing challenges and some recommendations for future directions have been brought in the concluding section of this paper.

Applications of carbon fiber reinforced epoxy-based composites have been highly restricted due to their high cost in the manufacturing process. Cellulose, a cheap and abundant material from nature, shows excellent mechanical property and structural stability. It shows huge potentials in substituting carbon fiber/epoxy with cellulose/epoxy composites to fulfill the great demands for composites with good performance and a reasonable price. This paper first reviews works about the preparation and regulation of cellulose materials based on the very basic concepts of top-down and bottom-up. Then research about the interfacial regulation between cellulose and epoxy has been discussed in two broad classes of covalent and non-covalent modification. Finally, the enhancement effect of cellulose reinforcement has been discussed in two broad classes of dispersive reinforcement and continuous phase reinforcement. The latter can be further divided into three classes according to the dimension feature (1D, 2D, and 3D). The results show that the nanolization of cellulose is necessary for guaranteeing the strength of composites, while the formation of macroscopic and continuous structures can ensure Young’s modulus of composites.

The photocatalytic mixed crystal nano-TiO2particles were incorporated with concrete by means of the internal doping method (IDM) and spraying method (SPM) in this paper. To evaluate the photocatalytic degradation efficiency of mixed crystal nano-TiO2concrete, the methyl orange (MO) was chosen to simulate pollutants. The physicochemical characteristics and photocatalytic performance of mixed crystal nano-TiO2concrete prepared by above two different methods were experimentally investigated under UV irradiation and solar irradiation. Furthermore, the effects of two key influential factors including pollutant concentration and irradiation condition were also analyzed and discussed. Experimental results indicate that the nano-TiO2concrete prepared by the spraying method (SPM) exhibits maximum photocatalytic degradation efficiency of 73.82% when the sprayed nano-TiO2slurry concentration is 10mg/L. The photocatalytic degradation efficiency of unpolished nano-TiO2concrete is much higher than that of polished nano-TiO2concrete under the same exposure time of UV irradiation. Moreover, the photocatalytic degradation efficiency of nano-TiO2concrete decreases with the increase of pollutant concentration. The irradiation condition has an obvious influence on the photocatalytic degradation efficiency of nano-TiO2concrete. In the aspect of applications, the practical recommendations for the nano-TiO2concrete with self-cleaning capacity were presented according to the experimental results.

With the development of integrated circuit technology, especially after entering the sub-micron process, the reduction of critical dimensions and the realization of high-density devices, the flatness between integrated circuit material layers is becoming more and more critical. Because conventional mechanical polishing methods inevitably produce scratches of the same size as the device in metal or even dielectric layers, resulting in depth of field and focus problems in lithography. The first planarization technique to achieve application is spin on glass (SOG) technology. However, this technology will not only introduce new material layers, but will also fail to achieve the global flattening required by VLSI and ULSI technologies. Moreover, the process instability and uniformity during spin coating do not meet the high flatness requirements of the wafer surface. Also, while some techniques such as reverse etching and glass reflow can achieve submicron level regional planarization. After the critical dimension reaches 0.35 microns (sub-micron process), the above methods cannot meet the requirements of lithography and interconnect fabrication. In the 1980s, IBM first introduced the chemical mechanical polishing (CMP) technology used to manufacture precision optical instruments into its DRAM manufacturing [1]. With the development of technology nodes and critical dimensions, CMP technology has been widely used in the Front End Of Line (FEOL) and Back End Of Line (BEOL) processes [2]. Since the invention of chemical mechanical polishing, scientists have not stopped studying its internal mechanism. From the earliest Preston Formula (1927) to today’s wafer scale, chip scale, polishing pad contact, polishing pad - abrasive - wafer contact and material removal models, there are five different scale models from macro to the micro [3]. Many research methods, such as contact mechanics, multiphase flow kinetics, chemical reaction kinetics, molecular dynamics, etc., have been applied to explain the principles of chemical mechanical polishing to establish models. This paper mainly introduces and summarizes the different models of chemical mechanical polishing technology. The various application scenarios and advantages and dis-advantages of the model are discussed, and the development of modeling technology is introduced.

Nanocarbon materials (carbon nanotubes, graphene, graphene oxide, reduced graphene oxide, etc.) are considered the ideal toughening phase of ceramic matrix composites because of their unique structures and excellent properties. The strengthening and toughening effect of nanocarbon is attributed to several factors, such as their dispersibility in the matrix, interfacial bonding state with the matrix, and structural alteration. In this paper, the development state of nanocarbon-toughened ceramic matrix composites is reviewed based on the preparation methods and basic properties of nanocarbon-reinforced ceramic matrix composites. The assessment is implemented in terms of the influence of the interface bonding condition on the basic properties of ceramic matrix composites and the methods used to improve the interface bonding. Furthermore, the strengthening and toughening mechanisms of nanocarbon-toughened ceramic matrix composites are considered. Moreover, the key problems and perspectives of research work relating to nanocarbon-toughened ceramic matrix composites are highlighted.

Influence of nano-strengthening immersion on the properties of recycled aggregate (RA) and recycled aggregate concrete (RAC) and the microstructure of interfacial transition zones (ITZs) between mortar and aggregate were studied in this paper. Results showed that nano-strengthening immersion was helpful to reduce the crushing value and total pore area of RA, to significantly improve the mechanical strength of RAC, and to modify the bond strength between RAC and steel rebar and the structural properties of RAC beams. Mercury intrusion porosimetry (MIP), micro-hardness (MH) and scanning electron microscope (SEM) observation were conducted in order to reveal the enhancement mechanism of nano-strengthening immersion. Results showed that the density and mechanical properties in ITZs were obviously improved by nano-strengthening because the coating and penetration of nano-materials was helpful to block the pores and cracks in ITZs, to avoid the directed gathering of CH crystal, and to accelerate the hydration of cement and mineral additions.

In recent years, with the higher requirements for the performance of cement-based materials and the call for energy conservation and environmental protection, a wave of research on new materials has set off, and various high-performance concrete and more environmentally friendly geopolymers have appeared in the public. With a view to solving the defects of energy consumption, environmental protection and low toughness of traditional cement-based materials. At the same time, nanomaterials have become a focus of current research. Therefore, the research on the properties of cement-based materials and geopolymers modified by graphene and its derivatives has aroused extensive interest of researchers. Graphene-based nanomaterials are one of them. Because of their large specific surface area, excellent physical properties have been favored by many researchers. This paper reviews the research progress of graphene-based nanomaterials in improving the properties of cement-based materials and geopolymer materials, and points out the main challenges and development prospects of such materials in the construction field in the future.

In this paper, the Cu-0.52Ag-0.22Cr alloy was prepared by hot horizontal continuous casting. The effects of aging process on micro-hardness, electrical conductivity, and nanoscale precipitates of Cu-0.52Ag-0.22Cr alloy were studied. The electrical conductivity and micro-hardness increase significantly in the early aging time. With the extension of aging time, the electrical conductivity is basically unchanged and remains at a high level. While, the micro-hardness increases slowly, the change trend is different at 623 K, 723 K, and 773 K. The optimisation of process parameters occurs in 723 K for 2 h. At this time, the electric conductivity is 95.8% IACS and the hardness is 104.1 HV0.1. The XRD result shows that the Ag and Cr are precipitated in elemental form copper matrix. Further TEM shows that, Cr exists at the sub-boundary in the form of larger nanoscale precipitates (100-200 nm). While a large number of Ag nanoscale precipitates (8-10 nm) is dispersed on the copper matrix. The synergistic effect of Ag and Cr nanoscale precipitates significantly improved the properties of the alloy.

In this paper, the 3D pore structure of CuCr powders were obtained by pre-press shaping process, and finally the 3D interconnected carbon nanotubes/copper (CNTs/Cu) composites with excellent properties were insitusynthesized by chemical vapor deposition (CVD) and spark plasma sintering (SPS) technique. The morphology and structure of CNTs/ Cu composites are characterized by scanning electron microscopy (SEM), Raman spectra, transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), and the results showed that the quality of CNTs and the interfacial bonding strength of CNTs/ Cu composites can be improved owing to the 3D pore structure. Meanwhile, the 3D pore structure was favorable to avoid pollution of CNTs during the synthesis process. The tensile strength of CNTs/ Cu composites increased to 421.2 MPa, with 47.6% enhancements compared to CuCr. Furthermore, the coefficient of friction (COF) reduced to 0.22 and the corrosion resistance were increased by 51.86% compared to CuCr. Consequently, our research provides a novel and an effective method for the synthesis of high quality CNTs/ Cu composites.

Carbon nanomaterials, predominantly carbon nanofibers, carbon nanotubes, graphene, graphene nanoplates, graphene oxide and reduced graphene oxide, possess superior chemical, physical and mechanical properties. They have been successfully introduced into ordinary Portland cement to give enhancements in terms of mechanical properties, durability and electrical/thermal conductivity, and to modify the functional properties, converting conventional cement-based materials into stronger, smarter and more durable composites. This paper provides a comprehensive review of the properties of carbon nanomaterials, current developments and novel techniques in carbon nanomaterials enhanced cement-based composites (CN-CBCs). Further study of the applications of CN-CBCs at industrial scale is also discussed.

Two-photon polymerization direct laser writing (TPP DLW) is an emerging technology for producing advanced functional devices with complex three-dimensional (3D) micro-structures. Tremendous efforts have been devoted to developing two-photon polymerizable photo-sensitive nanocomposites with tailored properties. Light-induced reconfigurable smart materials such as liquid crystalline elastomers (LCEs) are promising materials. However, due to the difficulties in designing two-photon polymerizable liquid crystal monomer (LCM) nanocomposite photoresists, it is challenging to fabricate true 3D LCE micro-structures. In this paper, we report the preparation of photo-sensitive LCE nanocomposites containing photothermal nanomaterials, including multiwalled carbon nanotubes, graphene oxide and gold nanorods (AuNRs), for TPP DLW. The printability of the LCE nanocomposites is assessed by the fidelity of the micro-structures under different laser writing conditions. DLW of GO/LCM photoresist has shown a vigorous bubble formation. This may be due to the excessive heat generation upon rapid energy absorption of 780 nm laser energy. Compared to pure LCM photoresists, AuNR/LCM photoresists have a lower laser intensity threshold and higher critical laser scanning speed, due to the high absorption of AuNRs at 780 nm, which enhanced the photo-sensitivity of the photoresist. Therefore, a shorter printing time can be achieved for the AuNR/LCM photoresist.

Nano-materials modified cement-based materials have attracted wide attention due to their advantages of improving strength and durability. In this paper, the effect of nano-SiO2(NS) with particle sizes of 15 and 50 nm on the mechanical properties and microstructure of cement paste was studied. The results showed that 50 nm NS provided a greater compressive strength than that of 15 nm NS, while 15 nm NS afforded a denser microstructure than that of 50 nm NS. A fluctuation in the compressive strength was revealed using a physicochemical reaction equation, and the microstructure was interpreted by a pore structure analysis. In addition, the orientation index of calcium hydroxide (CH) with 15 nm NS could be reduced significantly in the early stages (the early stages refer to the first three days from the maintaining of specimens) compared with when the 50 nm NS was used. The experimental results also showed that NS helped increase the mechanical strength of cement paste, advance the endothermic peak of CH, and refine the size of the CH crystals. The microstructural changes at different stages of cement paste with different particle sizes of NS were investigated by X-ray diffraction, scanning electron microscopy, mercury intrusion porosimetry and differential thermal analysis. This study is expected to promote the research and application of nano-materials in the cement industry by clarifying the performance of NS with different particle sizes.

Chromium (Cr) is a common toxic heavy metal that is widely used in all kinds of industries, causing a series of environmental problems. Nanoscale zero- valent iron (nZVI) is considered to be an ideal remediation material for contaminated soil, especially for heavy metal pollutants. As a material of low toxicity and good activity, nZVI has been widely applied in the in situremediation of soil hexavalent chromium (Cr(vi)) with mobility and toxicity in recent years. In this paper, some current technologies for the preparation of nZVI are summarized and the remediation mechanism of Cr(vi)-contaminated soil is proposed. Five classified modified nZVI materials are introduced and their remediation processes in Cr(vi)-contaminated soil are summarized. Key factors affecting the remediation of Cr(vi)-contaminated soil by nZVI are studied. Interaction mechanisms between nZVI-based materials and Cr(vi) are explored. This study provides a comprehensive review of the nZVI materials for the remediation of Cr(vi)-contaminated soil, which is conducive to reducing soil pollution.

A sustainable power source is more and more important in modern society. Ocean wave energy is a very promising renewable energy source, and it is widely distributed worldwide. But, it is difficult to develop efficiently due to various limitations of the traditional electromagnetic generator. In recent years, the newly developed triboelectric nanogenerator (TENG) provides an excellent way to convert water wave energy into electrical energy, which is mainly based on the coupling between triboelectrification and electrostatic induction. In this paper, a review is given for recent advances in using the TENG technology harvesting water wave energy. We first introduce the four most fundamental modes of TENG, based on which a range of wave energy harvesting devices have been demonstrated. Then, these applications’ structure and performance optimizations are discussed. Besides, the connection methods between TENG units are also summarized. Finally, it also outlines the development prospects and challenges of technology.

To achieve an efficient conductive network while preserving the properties of carbon nanofillers is a challenging and essential issue for the fabrication of highly conductive polymeric nanocomposites. The present paper reports a facile approach to manipulate the network formation in the polymer matrix via introducing the tetrapod ZnO whisker (T-ZnO) in the carbon nanotube (CNT)-reinforced epoxy composite. The influence of T-ZnO on the CNT dispersion was evaluated by UV-Vis spectroscopy, rheological measurement, scanning electron microscopy (SEM), and electrical and mechanical properties of the bulk composite. The results showed that the CNTs tend to disperse more uniformly with an increase in T-ZnO loading. An optimized ratio of 1:2 between CNTs and T-ZnO was found to significantly enhance the electrical conductivity by 8 orders of magnitude. A low percolation threshold of 0.25 wt% CNTs was achieved in this hybrid CNTs/T-ZnO composite, which is only 40% of the threshold value in the pure CNTs/epoxy. The flexural strength and modulus of the hybrid composite were also improved noticeably in comparison to the CNTs/epoxy. The mechanism for increasing the performance of the nanocomposite was analyzed. These results indicated that the T-ZnO can assist to efficiently improve the dispersion and the formation of the conductive network, which is beneficial to the enhancement of the mechanical and electrical performance of the nanocomposite.

The choosing of micromechanical environment is very important for the growth of bone-related cells. In this paper, bovine cancellous bone slices with 3D porous structures were used for 3D culturing of MC3T3-E1 cells (Mouse embryo osteoblast precursor cells) through a four-point-bending device due to their good biocompatibility and strength. Effects of micromechanical environment on the growth of MC3TC-E1 cells were investigated by immunofluorescent staining and alkaline phosphatase analysis, and the most positive microporous structures were found. In addition, a model of cell density vs stress was established through a specific normalization method and finite element simulation. The results showed that the micromechanical environment of the bone slices promoted cell proliferation, and the detail influence of stress on cell proliferation could be described by the mathematical model, which could provide a theoretical basis for the design of micromechanical environment in the bone tissue engineering scaffolds to stimulate cell proliferation.

High molar mass materials (nano-silica slurry [NSS] and aggregate of steel furnace slag [ASFS]) can improve concrete shielding properties. However, only a few studies have been reported in this regard. Hence, this paper aims to determine the effect of NSS and ASFS on the properties of the resulting steel slag heavyweight concrete (SSHWC). The use of NSS in this study is a novel contribution. Furthermore, the maximum percentage of NSS to be introduced into the concrete for maximum effect was also optimized. This study also implemented an investigation program with six concrete mixtures prepared using ASFS as the primary by-product aggregate. The engineering, X-ray, and γ-ray attenuation characteristics of the SSHWC were evaluated. The results showed that the addition of NSS in SSHWC at the optimal content of 3% by weight of cement improved the X-ray shielding by 6.4%. Besides, all the concrete’s engineering and γ-rays’ properties were enhanced correspondingly.

In this study, band gaps of SH-waves (horizontally polarized shear waves) propagating in a thermal-sensitive viscoelastic matrix are investigated. Metallic films acting as heat sources are periodically embedded into the matrix, which establishes a periodically inhomogeneous thermal field. The homogenous matrix is therefore transformed into functionally gradient phononic crystals (PCs). A three-parameter solid model is employed to describe the viscoelasticity of the present matrix. By virtue of a transfer matrix method incorporated within a laminated model, the dispersion equation of SH-waves is finally obtained, from which the band gaps are determined. The transmission spectra of a finite-periodic PC are also solved to validate the band gaps. In numerical examples, the influences of incident angles of SH-waves and viscoelasticity of matrix on band gaps are discussed first. Then the research focuses on the means to tune the band gaps by manipulating the inputted powers of heat sources. Numerical examples demonstrate that such a strategy is effective and convenient in tuning the positions and widths of band gaps. A viscous parameter, i.e., the ratio of initial-state to final-state storage moduli, significantly affects the band locations and bandwidths, while the locations of low-order band gaps hardly move with the incident angle of SH-waves. Band gaps of several orders are expected to locate in lower-frequency domain, and the total bandwidth becomes larger as the inputted heat flux increases. This paper lays theoretical foundation to manufacture viscoelastic functionally graded PCs which can be used in frequency-selective devices.

Recycling of red mud (RM) has attracted more attention in recent years due to severe environmental problems caused by landfilling. The effect of composition optimization and Nano-strengthening on the properties of a binder based on RM was studied in this paper. Results showed that modifying ratios of main oxides and adding Nano-SiO2could obviously affect the mechanical properties and microstructure of the binder. Specimens with high SiO2/Al2O3molar ratio (S/A) displayed considerable increase in compressive strength, while decreasing Na2O/Al2O3molar ratio (N/A) improved the workability of the fresh mix. The compressive strength was developed significantly to be 45 MPa at 28 days by adding Nano-SiO2with 0.4 wt.% of RM. Phase transformation and microstructure change at different stages of RM decomposition and binder geopolyerization were investigated by X-ray diffraction (XRD), Fourier transformation infrared (FTIR) and Scanning electron microscopy (SEM). The results of this study may provide a prospective method to use RM more widely in construction applications.

Halloysite nanotubes (HNTs) are natural tubular materials, which show a number of attractive advantages such as the unique micro-spatial structure, large length-diameter ratio, high lumen volume, nontoxicity and widespread. The development of HNTs-based polymer composites expanded their applications in the fields of energy, catalysis, biomedicine, environmental protection and many others. This review will briefly summarize the purification, characterization and modification methods upon HNTs, in which the preparation and application of the HNTs-based polymer composites are emphasized. This paper may be beneficial for the development of novel strategies for the preparation of new libraries of HNTs-based polymer composites and the exploration of their applications.

Adipose tissue reconstruction is an important technique for soft tissue defects caused by facial plastic surgery and trauma. Adipose tissue reconstruction can be repaired by fat transplantation and biomaterial filling, but there are some problems in fat transplantation, such as second operation and limited resources. The application of advanced artificial biomaterials is a promising strategy. In this paper, injectable biomaterials and three-dimensional (3D) tissue-engineered scaffold materials for adipose tissue reconstruction in plastic surgery are reviewed. Injectable biomaterials include natural biomaterials and artificial biomaterials, which generally have problems such as high absorptivity of fillers, repeated injection, and rejection. In recent years, the technology of new 3D tissue-engineering scaffold materials with adipose-derived stem cells (ADSCs) and porous scaffold as the core has made good progress in fat reconstruction, which is expected to solve the current problem of clinical adipose tissue reconstruction, and various biomaterials preparation technology and transformation research also provide the basis for clinical transformation of fat tissue reconstruction.

Nanostructures are widely used in nano and micro-sized systems and devices such as biosensors, nano actuators, nano-probes, and nano-electro-mechanical systems. The complete understanding of the mechanical behavior of nanostructures is crucial for the design of nanodevices and systems. Therefore, the flexural, stability and vibration analysis of various nanostructures such as nanowires, nanotubes, nanobeams, nanoplates, graphene sheets and nanoshells has received a great attention in recent years. The focus has been made, to present the structural analysis of nanostructures under thermo-magneto-electro-mechanical loadings under various boundary and environmental conditions. This paper also provides an overview of analytical modeling methods, fabrication procedures, key challenges and future scopes of development in the direction of analysis of such structures, which will be helpful for appropriate design and analysis of nanodevices for the application in the various fields of nanotechnology.