Search

To address corrosion problem of steel bars and shortage of freshwater and river sand in marine and offshore structures, a novel hydrophobic-modified longitudinal steel-FRP composite bars (SFCB) and FRP hoops reinforced low-alkalinity seawater sea-sand concrete (SWSSC) is developed. However, axial compressive behavior of hybrid SFCB and FRP reinforced columns is not clear and the applicability of existing design methods is low. Here, nine hybrid reinforced columns have been designed and tested. Typical failure modes of columns and axial compressive behavior of constituent materials (i.e. , hydrophobic reinforcements and low-alkalinity SWSSC) are investigated. It is found that the synergistic confining effect formed by hybrid reinforcement are significant. The mesh confinement formed by densely distributed FRP hoops and longitudinal SFCBs improves the local buckling behavior, and effectively constrains the lateral expansion of concrete core, resulting in improved compressive strength and ductility of column. The compressive contribution of single longitudinal SFCB to ultimate load capacity of column can be enhanced effectively, up to 36.3 %, by increasing steel content of SFCB. Based on this, a prediction model of hybrid reinforced columns is proposed, which can accurately evaluate the ultimate load capacity. This work provides valuable experimental observations and load capacity model for hybrid reinforced column, which promote its design and application in marine engineering. • Highly confined columns exhibit two peak loads with ductile failure mode. • Large SFCB diameter markedly enhances the load capacity of hybrid reinforced column. • A new load capacity prediction model is proposed considering synergistic confinement of SFCB and FRP hoop. • Hydrophobic SFCB and low-alkalinity SWSSC is promising for marine engineering. [ABSTRACT FROM AUTHOR]

In this study, the spheroidization behavior of the B2 phase in TiAl alloys under isothermal compression is revealed for the first time, reducing the cut apart trend on matrix. Results show that the deformation stored energy under the 1050 °C–40 %–0.01s−1 condition is insufficient so that most B2 phase bends and twists with the γ lamellae rather than being spheroidized. Under the 1000 °C–80 %–0.01s−1 condition, reduced temperature and increased strain further promote B2 phase spheroidization. The B2 phase nucleates and becomes spheroidized by twin boundary consumption within the γ lamellae. At the γ recrystallized grain boundary, the B2 phase grows into a spherical crown shape due to favorable slip tendency activation, multiple dislocation shear, and microslip bands coordination. This work offers a significant approach to improving the hot workability of TiAl alloys. [Display omitted] [ABSTRACT FROM AUTHOR]

To reveal the modification mechanism of carbides particles by in-situ Y 2 O 3 , and then the improvement mechanisms for Ti42Al6Nb2.6C- x Y alloys, the microstructures were observed by SEM, XRD and TEM, and the mechanical properties were examined. Results show that the flaky TiC transformed completely into Ti 2 AlC, and the morphology of Ti 2 AlC turned fine-needle shaped into short-rod shaped. The content of Ti 2 AlC with the aspect ratio of 1–5 increased from 24.2 to 81.4%, and the average aspect ratio decreased from 7.9 to 3.7 as Y increased from 0 to 0.08 at. %. The average lamellar colony size and lamellar spacing decreased from 24.054 to 17.500 μm and 0.531 to 0.304 μm, respectively. The growth of TiC phase was constrained by in-situ Y 2 O 3 , which alleviated agglomeration distribution of TiC and provided a fine TiC substrate for the nucleation of Ti 2 AlC. The interfacial interaction between in-situ Y 2 O 3 and Ti 2 AlC restricted the longitudinal and transverse growth of Ti 2 AlC. The modified Ti 2 AlC and in-situ Y 2 O 3 particles as nucleation sites for β grains were the basis for obtaining fine lamellar structure. For mechanical properties, the compressive strength increased from 1388 to 1781 MPa, the yield strength increased from 1265 to 1544 MPa, and the Vickers hardness increased from 495 to 609 HV. The refinement of lamellar colony by modified Ti 2 AlC and in-situ Y 2 O 3 , and the load strengthening of Ti 2 AlC particle contributed to the mechanical properties. [Display omitted] • The complete transformation of Ti 2 AlC particles was promoted by in-situ Y 2 O 3. • The interfacial interaction between in-situ Y 2 O 3 and Ti 2 AlC inhibited the growth of Ti 2 AlC particle. • The relative content of Ti 2 AlC particle with the aspect ratio of 1–5 increased by 3.4 times by adding 0.08 at. % Y. • The compressive strength and Vickers hardness were improved by 1.3 and 1.2 times by adding 0.08 at. % Y. [ABSTRACT FROM AUTHOR]

• Effect of titanium dioxide and graphene on the durability and mechanical properties of polyether sealant is studied. • Tensile strength after ultraviolet exposure of modified sealant improved by 102%. • Water absorption of graphene-modified sealant reduced by 85.7%. • The working mechanism of sealant with titanium dioxide and graphene has been revealed. The silane-modified polyether sealant is widely applied to fill the gaps between external walls in prefabricated buildings and to bear the deformation of joints. However, the weak tensile strength and poor ultraviolet and moisture resistance of sealant lead to severe degradation, posing threat to the building waterproofing and safety. To address the problems, titanium dioxide and graphene were adopted to improve the mechanical properties and durability of sealant. The tack-free time, tensile properties, ultraviolet resistance, and hydrophobic performance of pristine and modified sealant were investigated and the enhancement and erosive resistance mechanisms of modified sealant were revealed by microscale characterization. Results indicated that modified sealant with low content of titanium dioxide had greater tensile strength and ultraviolet resistance. The crystalline form of titanium dioxide and produced Si-O bond enhanced the ultraviolet resistance. Moreover, the 0.8% graphene-modified sealant possessed superior moisture resistance with 23% increased contact angle. Graphene increased the surface roughness and generated π-conjugated structure, improving sealant hydrophobicity. It is revealed that the enhanced properties were ascribed to the spatial structure of fillers and chemical bond energy. This work provides a novel sealant with high ultraviolet resistance and hydrophobicity, facilitating the development of durable and low-maintenance prefabricated buildings. [ABSTRACT FROM AUTHOR]

To form in situ nano-borides in the solid-liquid two-phase region, Ti46 A l8Nb2·6C0.8Ta x B alloys were prepared under ultrasound to improve the microstructural and mechanical properties. The morphology and distribution of borides and the characteristics of lamellar colonies were observed with scanning and transmission electron microscopy and X-ray diffraction; these analyses revealed the influence of borides on microstructural evolution and improved strength and plasticity. The borides that form are elongated and spherical. As the B content increases, the borides gradually spheroidise, and nano-borides precipitate on the lamellar phase. There are a large number of dislocations around the borides to form stacking faults and dislocation walls. The average size of the lamellar colonies decreases from 26.9 to 19.3 μm. The increase in boride nucleation sites as the B content increases and ultrasound-mediate breaking of primary borides are the reasons for forming B27-type borides. The increase in nucleation particles refines the lamellar colony. The compressive strength increases from 2058 to 2299 MPa, and the strain increases from 25.2% to 32.3% when the addition of B increases from 0% to 1.2%. The significantly improved mechanical properties are due to uniformly distributed nano-borides that hinder the movement of dislocations to form stacking faults and dislocation walls and refinement of the lamellar colonies. [ABSTRACT FROM AUTHOR]

The development of underground space is an important trend for urban infrastructure in cities supporting socio-economic activities, while it also results in an enormous accumulation of sediment waste, which consumes vast land resources, causes serious environmental problems and endangers public safety. It is urgent to explore pathways of recycling sediment waste with low carbon impact for sustainable infrastructure. This study employed calcination and alkali activators to recycle sediment waste into geopolymer paste. The mechanical properties and working performance of recycled geopolymer paste were investigated and the underlying mechanism of this recycling scheme was revealed with microscale characterizations. Results showed that the compressive strength of recycled geopolymer paste could reach 50 MPa. The environmental impact of geopolymer paste and cement-based paste has been analyzed via life cycle assessment (LCA). Recycled geopolymer paste can save 310 kg CO 2 eq/t of carbon emissions, which is 39% lower than that of cement-based material. Moreover, the multi-criteria approach was adopted to evaluate geopolymer paste and cement paste considering mechanical properties, working performance, carbon emissions, energy consumption and cost, and geopolymer paste exhibits better overall performance. The findings inspire a construction waste management strategy and contribute to low-carbon construction materials for sustainable urban infrastructure. • Sediment waste is recycled into geopolymer paste via calcination and alkali activator. • The optimum mix ratio range of geopolymer paste with sediment waste is determined. • Mechanical and environmental performance of geopolymer paste has been studied. • A sustainable sediment waste management strategy and a low-carbon construction material is inspired. [ABSTRACT FROM AUTHOR]

The precise modeling of the instantaneous undeformed chip thickness is one of the key issues in the mechanics of micromilling. While most current models noticed the influences of the tool tip trochoidal trajectory and tool runout, they took account only the workpiece removed by immediate passing tooth but not more preceded teeth. These lead to inaccuracy when the single edge cutting occurred, which has been identified to be a prevalent phenomenon in micromilling operation. In this paper, the actual cutting area in micromilling is derived, and then a generic instantaneous undeformed chip thickness model is proposed by considering the cutting trajectory of all passing teeth in one cycle. Additionally, this study derives a criterion that could determine the single-edge-cutting phenomenon in multi-tooth micromilling from the geometric relations. The accuracy of the model is verified by the real experimental data and the result are shown superior to known models. [ABSTRACT FROM AUTHOR]

Abstract: A method to prepare wide-band reflection cholesteric liquid crystals (CLCs) films by thermally induced diffusion of dye was proposed. Due to the greatly enhanced UV intensity gradient formed by thermal diffusion of dye, the pitch gradient was formed and fixed after the process of photoinduced polymerization and diffusion of CLC monomers. Using this method, the prepared CLCs film can reflect circularly polarized light over a broad wavelength range of 750–2400nm. The pitch gradient of the CLC film was observed by scanning electron microscopy (SEM). In addition, the influence of dye concentration, thermal diffusion time and thermal diffusion temperature on the consequent pitch gradient was systemically studied. [Copyright &y& Elsevier]

Abstract: In this study, we demonstrate a novel method for fabricating a single layer cholesteric liquid crystal (CLC) film with non-uniform pitch distribution by utilizing the chiral polynetworks. A chiral monomer, the helical twist power (HTP) of which decreases with the increase of temperature, was synthesized. The temperature dependence of the pitch of the mixtures before and after polymerization was investigated. To broaden the reflection band, the experimental processes of thermally induced pitch variation were presented. The results suggest that the chirality of the polymer network plays an integral role in the reflection spectra. Additionally, scanning electron microscopy (SEM) was used to examine the role of the polymer network induced by polymerization temperature. These wide-band reflection optical properties make the CLC gels interesting for their potential applications in many fields, such as colour filters, brightness enhancement films, smart switchable reflective windows etc. [ABSTRACT FROM AUTHOR]

Large-scale expansion of urban underground space has led to the accumulation of substantial sediment. Now the primary disposal approach involves long-distance transport followed by dumping in open areas or landfills, incurring excessive deposition and causing landslides. To tackle this concern, a novel processing scheme that transforms sediment into supplementary cementitious material is proposed for preparing sustainable seawater sea sand concrete (SWSSC). Notably, it is determined that this transformed sediment improves cement hydration and reduces cement dosage, achieving a 35% reduction in CO 2 emissions compared to traditional SWSSC with identical strength according to life cycle assessment. Furthermore, it offers the additional benefit of cost-effective. Microanalysis has demonstrated that the recycled sediment reacts with calcium hydroxide and produces secondary calcium-silicate-hydrate gel, contributing to the mechanical properties and decrease in alkalinity of SWSSC. A design model for SWSSC is proposed, focusing on alkalinity, mechanical strength, and environmental benefits. This proposed model enhances application of SWSSC in construction, catering to specialized marine engineering structures, like artificial islands, harbors and offshore structures. This study contributes to a large-scale processing strategy of sediment and provides an economical and green alternative construction material for sustainable infrastructures. [Display omitted] [ABSTRACT FROM AUTHOR]

Graphic 1. Schematic illustration of anti-dysfunctional activities exerted by non-split HDL and proatherosclerotic effects induced by OxHDL. [Display omitted] Numerous studies have demonstrated that dysfunctional high-density lipoprotein (HDL), especially oxidized HDL (OxHDL), could generate multifaceted in vivo proatherogenic effects that run counter to the antiatherogenic activities of HDL. It thereby reminded us that the in vitro reconstituted HDL (rHDL) might encountered with oxidation-induced dysfunction. Accordingly, a green-inspired method was employed to recycle non-split HDL from human plasma fraction IV. Then it was compared with rHDL formulated by an ethanol-injection method in terms of physicochemical properties and anti-dysfunctional activities. Results exhibited that rHDL oxidation extent exceeded that of non-split HDL evidenced by higher malondialdehy content, weaker inhibition on low-density lipoprotein (LDL) oxidation and more superoxide anion. The reserved paraoxonase-1 activity on non-split HDL could partially explain for above experimental results. In the targeted transport mechanism experiment, upon SR-BI receptor inhibition and/or CD36 receptor blockage, the almost unchanged non-split HDL uptake in lipid-laden macrophage indicated its negligible oxidation modification profile with regard to rHDL again. Furthermore, compared to rHDL, better macrophage biofunctions were observed for non-split HDL as illustrated by accelerated cholesterol efflux, inhibited oxidized LDL uptake and lessened cellular lipid accumulation. Along with decreased ROS secretion, obviously weakened oxidative stress damage was also detected under treatment with non-split HDL. More importantly, foam cells with non-split HDL-intervention inspired an enhanced inflammation repression and apoptosis inhibition effect. Collectively, the anti-dysfunctional activities of non-split HDL make it suitable as a potential nanocarrier platform for cardiovascular drug payload and delivery. [ABSTRACT FROM AUTHOR]

Precision machining has been claimed to be the backbone to modern industry. It has been widely applied to the key parts’ production in the aerospace, medical and automotive industries. One of the main problems related to precision machining productivity and safety is the machining condition. By utilizing the acquired information from sensory measurements to direct the further actions, the signal processing bridges the gap between human instruction and full automation. Traditional signal acquisition and processing methods are mainly based on Shannon’s Sampling theory, Fourier methods or wavelet analysis. While these techniques meet challenges in precision machining environment, such as machining at high speed, low signal to noise ratio, and high sampling rate. These factors limit their applications especially the online monitoring implementation. The newly developed compressive sensing theory and sparse decomposition techniques provide a possible solution to these problems, while limited studies have been investigated. This paper serves as an introduction to the theory and shows the theory’s potentials in machining condition monitoring by reviewing related literatures and demonstrating case studies from real experiments. [ABSTRACT FROM AUTHOR]

Abstract: This study indicated that the smectic-like short-range order (SSO) provided an opportunity to improve the planar orientation of chiral nematic liquid crystal (N*-LC) molecules while increasing the light transmittance of the N*-LC cells. The SSO formed between N*-smectic A (SmA) transition was first introduced into N*-LC compositions and then applied a specific thermal process at the temperature of SSO (T SSO). Finally, the uniform alignment of the N*-LC molecules was obtained. Decreasing the heating rate and extending the holding time at T SSO were effective at reducing the oily streak and perfecting the planar texture of the N*-LC cells. And this method was also resultful for N*-LC composites exhibited different pitches. [Copyright &y& Elsevier]

To study the recycling of bauxite tailings (BT) and the poor water resistance of magnesium phosphate cement (MPC), the effects of BT and calcined BT (CBT) on the setting time, fluidity, drying shrinkage properties, compressive strength, and water resistance of MPC were investigated. The results showed that BT and CBT regulated the setting time and fluidity of MPC, adjusted the pH of the MPC paste, and decreased the generation rate of hydration products. The incorporation of BT decreased the early strength and increased the late strength of MPC, while the incorporation of CBT increased the MPC strength during the 28 d duration. Further, the optimal incorporation amount of BT and CBT was found to be 15 wt%. Although the water resistance of MPC was improved by blending BT or CBT, the effect of CBT was more significant, with a 32% reduction in compressive strength loss in the CBT groups compared to the control group for 28 d of curing. The alumina in BT was calcined and activated such that AlPO 4 produced by secondary hydration reaction with phosphate enhanced the bonding of the solids and filled the pores and cracks of the MPC specimens, thereby increasing the densities of the specimens and improving their water resistance. ● The effects of BT before and after calcination on MPC properties was studied. ● The incorporation of CBT significantly increased the compressive strength of MPC. ● The activated alumina in CBT produced AlPO 4 to enhance the density of MPC. [ABSTRACT FROM AUTHOR]

Abstract In this paper, we report the design, preparation and properties of epoxy-mercaptan polymer/nematic liquid crystal (LC) composites with electrically switchable optical transmittance. It is found that the polymer microstructure can be regulated from porous structure to microspheres or beads by appropriately modulating the curing temperature, the molecular structure of mercaptan, as well as the compositions of epoxy, mercaptan and nematic LC host. Under an external electric field, the thin films based on such composites can switch from opaque to transparent. The electro-optical performance is found to be highly dependent on the polymer microstructures and the optimum characteristics can be achieved in the composite with a microstructure of smaller microspheres. The possible mechanism for the formation of polymer microspheres and the effects of the microstructures on the electro-optical characteristics of the composites are also discussed. This work is expected to provide an efficient way to control the microstructure of epoxy/mercaptan polymer and develop the composites with switchable optical transmittances for both civil and military applications. Graphical abstract Image 1 Highlights • Epoxy-mercaptan polymer/LC composites with electrically switchable optical transmittance were successfully prepared. • The morphology of the polymer can be modulated from porous to microspheres structure by adjusting the preparation condition. • The possible mechanism for the formation of epoxy-mercaptan polymer microspheres in LC was discussed. • The effects of the polymer microstructures on the electro-optical characteristics of the composites were elucidated. [ABSTRACT FROM AUTHOR]

The feasibility of the degradation of phenazone (PNZ), a common anti-inflammatory drug used for reducing pain and fever, in water at neutral pH by an electrochemically assisted Fe3+-ethylenediamine disuccinate-activated persulfate process (EC/Fe3+-EDDS/PS) was investigated. The efficient removal of PNZ at neutral pH condition was mainly attributed to the continuous activation of PS via electrochemically driven regenerated Fe2+ from a Fe3+-EDDS complex at the cathode. The influence of several critical parameters, including current density, Fe3+ concentration, EDDS to Fe3+ molar ratio, and PS dosage, on PNZ degradation was evaluated and optimized. Both hydroxyl radicals (•OH) and sulfate radicals (SO 4 ●–) were considered major reactive species responsible for PNZ degradation. To understand the mechanistic model of action at the molecular level, the thermodynamic and kinetic behaviors of the reactions between PNZ with •OH and SO 4 ●– were theoretically calculated using a density functional theory (DFT) method. The results revealed that radical adduct formation (RAF) is the most favorable pathway for the •OH-driven oxidation of PNZ, while single electron transfer (SET) appears to be the dominant pathway for the reaction of SO 4 ●– with PNZ. In total, thirteen oxidation intermediates were identified, and hydroxylation, pyrazole ring opening, dephenylization, and demethylation were speculated to be the major degradation pathways. Furthermore, predicted toxicity to aquatic organisms indicated that PNZ degradation resulted in products that were less harmful. However, the developmental toxicity of PNZ and its intermediate products should be further investigated in the environment. The findings of this work demonstrate the viability of effectively removing organic contaminants in water at near-neutral pH by using EDDS chelation combined with electrochemistry in a Fe3+/persulfate system. [Display omitted] • An EC/Fe3+-EDDS/PS process was proposed to remove PNZ from water at neutral pH. • The influence of critical parameters on the degradation of PNZ was evaluated. • A radical-mediated reaction mechanism was elucidated by DFT calculations. • Multiple degradation pathways for PNZ were proposed according to the products formed. • The ecotoxicity of PNZ and its degradation products was evaluated. [ABSTRACT FROM AUTHOR]

Because of the special needs for nanosecond double pulse applications in micromachining and material processing, we demonstrated a stable nanosecond dual-pulse erbium-doped fiber laser based on nonlinear polarization rotation technology. The fiber laser operates in a normal dispersion regime with a length of 256 m OFS-980 fiber. With the pump power of 1120 mW, the laser generates a highly stable dual-pulse train with the pulse widths of 6.2 ns and 1.2 ns respectively. By simply changing the pump power, the pulse width of one of dual-pulse can be tuned from 2.1 to 6.2 ns while the other pulse keeping almost the same duration of 1.2 ns. The maximum dual-pulse energy is about 72.5 nJ with a repetition rate of 783.3 kHz. The formation of such nanosecond dual-pulse is attributed to the pulse splitting and depends on the parameters of the laser cavity, such as the cavity-length and the state of polarization controller. The experiment of a single square pulse splitting into different shapes of nanosecond dual-pulse was demonstrated. [ABSTRACT FROM AUTHOR]

As a regulator of actin filament turnover, Arabidopsis thaliana CAP1 plays an important role in plant growth and development. Here, we analyzed the phenotypes of two Arabidopsis cap1 mutants: cap1-1 (a T-DNA insertion mutant) and Cas9-CAP1 (generated by CRISPR-Cas9 gene editing). Phenotypic analysis demonstrated that loss of CAP1 results in defects in seed germination and seedling morphology, with some seedlings exhibiting one or three cotyledons. The cap1-1 mutant took longer than the wild type to complete its life cycle, but its flowering time was normal, indicating that loss of CAP1 prolongs reproductive but not vegetative growth. Moreover, loss of CAP1 severely reduces seed production in self-pollinated plants, due to disruption of pollen tube elongation. RNA-seq and qRT-PCR analyses demonstrated that CAP1 may be involved in osmotic stress responses. Indeed, the cap1-1 mutant showed increased tolerance of salt and mannitol treatment, indicating that CAP1 plays a negative role in osmotic stress tolerance in Arabidopsis. Taken together, our results demonstrate that CAP1 functions not only in plant growth and development, but also in Arabidopsis responses to osmotic stress. [ABSTRACT FROM AUTHOR]

14–3-3 proteins, a family of conserved molecules in eukaryotes, target a number of protein clients through their ability to recognize well-defined phosphorylated motifs. ADF4, as one of Actin-Depolymerizing Factor (ADF) family of proteins, is involved in plant development, and response to biotic and abiotic stresses. Here, we show that 14–3-3κ specially interacted with ADF4 in vitro and in vivo. The 14–3-3κ×adf4 double mutant displayed less F-actin bundle and shorter hypocotyl compared with adf4 mutant, indicating that 14–3-3κ acts upstream of ADF4 to mediate the hypocotyl growth in the dark-grown seedlings. Under the osmotic stress, 14–3-3κ mutants displayed less survival rate than wild-type plants. The adf4 mutants exhibited markedly enhanced survival rate under osmotic treatment, while ADF4 -overexpressing plants displayed the opposite results, indicating that ADF4 plays a negative role in response to osmotic stress in Arabidopsis. The interaction between ADF4 and 14–3-3κ inhibited the association of ADF4 with actin filament. Moreover, the in vitro phosphorylation assay demonstrates that the phosphorylation of ADF4 by CASEIN KINASE1-LIKE PROTEIN2 (CKL2) was enhanced by binding 14–3-3κ. Collectively, our data infer a fundamental role for the interaction between 14–3-3κ and ADF4 in regulating hypocotyl growth and osmotic tolerance of plants. • ADF4 specially interacts with 14–3-3κ, but not other isoforms; • The involvement of 14–3-3κ regulates the hypocotyl growth with ADF4; • The interaction between ADF4 and 14–3-3κ mediates plants response to osmotic stress; • The phosphorylation of ADF4 by CKL2 is enhanced by 14–3-3κ and then leads to disassociate from F-actin. [ABSTRACT FROM AUTHOR]

Abstract: A series of novel side-chain cholesteric liquid-crystalline elastomers based on polysiloxane and cholesterol derivate monomer were prepared by adopting a crosslinking agent containing binaphthalene group. The chemical structures and mesomorphic properties of the monomers and elastomers were confirmed by FT-IR, 1H NMR, DSC and POM measurements. Worthily, the elastomers exhibited unusual temperature dependence of the helical twisting power (HTP) which is demonstrated resulting from coordination of the crosslinking agent and the mesogenic units. With increase in temperature, the HTP of elastomers containing small quantity of the crosslinking unit exhibited a turning point, while that of elastomers comprising much more crosslinking unit shifted straight. Furthermore, a single layer wide-band reflective film with non-uniform pitch distribution was prepared by utilizing the HTP variety of elastomers with change in temperature. From scanning electron microscopy (SEM) investigations, the mechanism of the broadband reflection was verified. [Copyright &y& Elsevier]