The digital image correlation (DIC) technique was applied to the analysis of displacement fields along the surface cracks of ultra-high-performance fiber-reinforced concrete (UHPFRC) under a bending ...load. Analysis was performed on the fiber bridging forces acting on a unit area of cracked sections belonging to different regions (perfect bonding region, partial debonding region, and full debonding region), according to the fiber distribution characterization and DIC data. By using the DIC technique, the visualization and quantification of the UHPFRC fracture properties could be determined. The length of the uniform zone increased, whereas the fracture process decreased under the external load of the limit of proportionality (LOP). With the appearance of macro-cracks under the external load of the modulus of rupture (MOR), the length of the uniform and fracture process zones increased as the fiber content increased. However, the localization zone decreased. The steel fiber volume fractions had limited influence on the tensile strain at cracking and the complete debonding of fibers.
A simple, new type of chiral sulfinamide monophosphines, the so‐called Ming‐Phos ligands, is reported; these ligands could be easily prepared from inexpensive and commercially available starting ...materials. The Ming‐Phos ligands performed well in the enantioselective gold‐catalyzed cycloaddition reaction of 2‐(1‐alkynyl)‐alk‐2‐en‐1‐ones with nitrones. Both enantiomers of the products could be obtained in good yields and with excellent diastereo‐ and enantioselectivity through transformations that were catalyzed by gold complexes derived from two diastereomers of Ming‐Phos ligand M5 (Ar=1‐naphthyl).
Ming‐Phos: A new type of simple chiral sulfinamide monophosphine ligands, the so‐called Ming‐Phos ligands, can be easily prepared from inexpensive and commercially available starting materials. The enantioselectivity of the reaction of yne–enones 1 with nitrones could be controlled by the diastereomeric ligands (R,RS)‐M5 and (S,RS)‐M5.
Using eggshell powder (EP) to replace partial cement in cement-based materials can abate pollution caused by eggshell discard and cement production. In this paper, the surface property of EP and its ...influence on cement hydration were studied. Quartz powder (QP) and limestone powder (LP) were used as references. First, the chemical composition of EP was characterized. Then, the surface charge properties of these materials were analyzed using zeta potential measurement. The interactions between EP surface and Ca2+ were discussed based on the zeta potential test. Afterward, a scanning electron microscope (SEM) was applied to observe the morphology of hydrates on the surfaces of these materials. The results indicated that, although the compositions of EP and LP are similar, the surface charge properties are significantly different. This is likely due to the existence of organic matter on the surface of EP and the difference in the atomic structure. As shown from the zeta potential test, EP exhibits similar interaction with Ca2+ as QP. The interactions between EP surface and Ca2+ are much weaker than that between LP and Ca2+. These weak interactions lead to the growth of C–S–H on the surface of EP particles less than that of LP particles. The chemical reactivity of EP can be improved by using heat treatment, electrical oven, etc. This study will provide theoretical support for the better use of EP in cement-based materials.
The utilization of marine waste and resources to produce eco-friendly building materials is essential for the sustainable development of the construction industry on islands and coastal areas. The ...sea sand and coral sand sourced from coral waste are the most promising. Therefore, the objective of this work is to investigate the feasibility of coral/sea sand as fine aggregate to prepare an environment-friendly marine mortar. The effects of various volume fractions of coral sand intended to replace sea sand on the flowability, physical performances, carbonation resistance, and microstructure of the prepared marine mortars were evaluated. The experimental results showed that as the sea sand replacement by coral sand was increased, the flowability and dry bulk density decreased, while the water absorption increased. Encouragingly, usage of a combination of coral and sea sands enhanced the flexural strength of marine mortars. A mixture containing 80 vol% of coral sand showed the best effect. The carbonation depth of marine mortar was found to noticeably increase with increasing replacement ratios of sea sand by coral sand, closely relating to the increase in the volume of capillary and large pores. In particular, the combined utilization of coral sand and sea sand resulted in a compacted interfacial transition zone (ITZ) between fine aggregates and the matrix.
•Physical properties and carbonation resistance of marine mortar were evaluated.•The addition of coral sand can improve the flexural strength of marine mortar.•Incorporating coral sand markedly increase the carbonation depth of marine mortar.•Combined use of coral and sea sands in marine mortar can promote compaction of ITZ.
Aconitum transsectum Diels. (Ranunculaceae) is an important medicinal plant that is widely used in traditional Chinese medicine, but its morphological traits make it difficult to recognize from other ...Aconitum species. No research has sequenced the chloroplast genome of A.transsectum, despite the fact that phylogenetic analysis based on chloroplast genome sequences provides essential evidence for plant classification.
In this study, the chloroplast (cp) genome of A. transsectum was sequenced, assembled, and annotated. A. transsectum cp genome is a 155,872 bp tetrameric structure including a large single copy (LSC, 87,671 bp) and a small single copy (SSC, 18,891 bp) section, as well as a pair of inverted repeat sequences (IRa and IRb, 25,894 bp each). 131 genes are encoded by the complete cp genome, comprising 86 protein-coding genes, 37 tRNAs, and 8 rRNAs. The most favored codon in the A. transsectum cp genome is AUG, and 46 repeats and 241 SSRs were also identified. The A. transsectum cp genome is similar in size, gene composition, and IR expansion and contraction to the cp genomes of seven Ranunculaceae species. Phylogenetic analysis of cp genomes of 28 plants from the Ranunculaceae family shows that A. transsectum is most closely related to A. vilmorinianum, A. episcopale, and A. forrestii of Subgen. Aconitum.
Overall, this study provides complete cp genome resources for A. transsectum that will be beneficial for identifying potential.
This study investigates the flexural behavior of UHPC materials containing steel fibers of varying lengths. Mesomechanical analysis is performed according to the analytical pullout model, using ...actual measured fiber distributions. The flexural behavior of UHPC after cracking is simulated by superposing the fiber bridging and matrix softening curves. Subsequently, the evolution of stress–strain along the axial crack of UHPC is evaluated under different loading conditions. The obtained results indicate that longer steel fibers can efficiently improve the flexural behavior of UHPC. Moreover, the actual fiber orientation and pullout length distributions can be well fitted by two-parameter probability distribution (PDF) and Gaussian functions, respectively. Based on the micromechanical analysis, the fiber bridging behavior is overestimated under the assumption of 2D random fiber distribution, and it is underestimated under the assumption of 3D random fiber distribution. Interestingly, the length of the shear lag zone is independent of the fiber length, which is about 20.16 mm. The obtained results demonstrate that the compressive stress and strain at the top of the tested specimen gradually transform into tensile stress and strain at the opposite side. Interestingly, the stress of the specimens with fiber length of 20 mm are slightly higher than the specimens with fiber lengths of 6 and 13 mm, and the strain just lower than the specimens with fiber lengths of 6 and 13 mm in all crack propagation stages, respectively. This indicates that, in addition to the number of steel fibers, the stress/strain dispersion depends on fiber length.
This study investigated the fatigue crack propagation behavior of ultra-high-performance concrete (UHPC) incorporated with different steel fiber lengths of 6, 13, and 20 mm under flexural cyclic ...loading, based on the Paris law and nonlinear fracture mechanics. In addition, multiple crack covering areas and fatigue J-integral amplitudes were employed to quantitatively evaluate the fatigue crack propagation rate and predicate the fatigue life of the UHPC during the steady development stage. The results indicated that the maximum crack opening displacement (COD) values were 0.312, 0.673, and 1.265 mm and the minimum crack growth rates were -3.05, -4.48 and -4.62 for SF6, SF13, and SF20, respectively. The critical crack length was approximately 65 mm for UHPC specimens containing different fiber length at a given fiber volume fraction (2.0%), indicating that the critical crack length was simply related to the fiber length. Interestingly, when the fatigue crack area of all the tested series reached approximately 35 mm2, fracture failure occurred. There were very small predictions between the actual tested and predicated fatigue lives, all less than 7.21%. Hence, it was reasonable to predict the fatigue life of the UHPC based on the J-integral according to the DIC technique.
In this work, we present a plasmonic platform capable of the enhanced electric field (E-field) intensity, tunable LSPR effect, and trapping nanoparticles in different configurations of Ag triangular ...nanoplates. Our nanostructures equip the higher structural anisotropy (larger aspect ratio, 10:1), which localize surface plasmons in the gap region and possess the great factor of E-field enhancement (~850). Tunable near-field enhanced hotspots of Ag nanoplates support different resonant modes from 350 to 1200 nm, and the distribution of electric field and trapping potential well can also be manipulated. The hotspots for dimer enhance the optical force (~3.2 nN) on 30-nm polystyrene nanoparticles with a power density as low as 1 mW/μm
2
, which shows brilliant trapping characteristics. The tetramer with higher periodic symmetry provides a deep potential well (~
1.3
×
10
3
k
B
T). It offers opportunities for the trapping and manipulating particles of nanoscale. And the nanogap structures pave a way for applications in surface-enhanced Raman scattering, surface-enhanced infrared absorption tunable biosensors.
By optimizing the distribution of steel fibers in fiber-reinforced cementitious mortar (FRCM) through the layered structure, the role of fibers can be fully utilized, thus improving the flexural ...behavior. In this study, the flexural behavior of layered FRCM at different thicknesses (25 mm, 50 mm, 75 mm, 100 mm) of the steel fiber layer was investigated. The evolution of the crack propagation behavior was analyzed using the digital image correlation (DIC) technique. The results showed that the steel fiber layer thickness of 75 mm has the best flexural behavior. Moreover, the crack propagation path is more tortuous. The maximum value of crack opening displacement (COM) increases with the increase in fiber thickness. In addition, increasing the bottom layer thickness can increase the height of the tensile zone, but the interface inhibits the increase of the tensile zone.
Graphene (G) and graphene oxide (GO) have been shown to significantly improve the mechanical properties of cement-based materials. In this study, the effect of the G/GO on cement hydration was ...investigated. First, the zeta potential of G/GO in simulated solutions was tested, and the interaction between G/GO’s surface and Ca
was explored. Subsequently, scanning electron microscopy was used to observe the morphology of C–S–H nucleation and growth on the cement surface in the cement paste containing G/GO. Furthermore, XRD and TGA analyses were carried out on the hydration products of the sample. At last, isothermal calorimetry was applied to investigate the influence of G/GO on the early hydration of cement. The results showed that the addition of G/GO significantly accelerates C–S–H nucleation and growth on the cement surface. It is indicated that the high mobility ions derived by G/GO in the cement paste dominate the reason for the accelerated hydration of cement. The presence of G, especially GO, facilitates the mobility of ions, especially Ca
, thus enhances the interaction between the cement surface and the ions. This strong interaction promotes the C–S–H nucleation and growth, and therefore, the hydration of the cement.
(1) GO has a strong interaction with Ca
. (2) G/GO accelerates C–S–H growth. (3) High mobility ions derived by G/GO facilitate hydration.
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