Search

Cocrystallization integrates the merits of high energy and insensitivity between energetic molecules to obtain energetics with satisfying performance. However, how to obtain supramolecular synthons accurately and rapidly for predicting the structure and property of cocrystal remains a challenging problem. In this research, an efficient systematic search approach to predict CL-20/2,4-DNI cocrystal has been proposed that 2,4-DNI revolves around CL-20 with a stoichiometric ratio of 1:1 in accordance with the specified rules (hydrogen bond length: 2.2–3.0 A; search radius: 6.5 A; the number of hydrogen bond: 1–3). Eight possible supramolecular synthons were obtained by combining quantum chemistry with molecular mechanics. Crystal structure prediction indicated that there are four structures in cocrystal, namely P21/c, P212121, Pbca and Pna21, and CL-20/2,4-DNI cocrystal is likely to be P21/c and the corresponding cell parameters are Z = 4, a = 8.28 A, b = 12.17 A, c = 20.42 A, α = 90°, β = 96.94°, γ = 90°, and ρ = 1.9353 g/cm3. To further study the intermolecular interaction of CL-20/2,4-DNI cocrystal, a series of theoretical analyses were employed including intermolecular interaction energy, electrostatic potential (ESP), Density of State (DOS), Hirshfeld surface analysis. The C–H⋯O hydrogen bonds are demonstrated as the predominant driving forces in the cocrystal formation. The mechanical properties and detonation properties of CL-20/2,4-DNI cocrystal implies that the cocrystal shows better ductility and excellent detonation performances (9257 m/s, 39.27 GPa) and can serve as a promising energetic material. Cocrystal structure predicted was compared with the experimental one to verify the accuracy of systematic search approach. There is a less than 8.8% error between experiment and predict results, indicating the systematic search approach has extremely high reliability and accuracy. The systematic search approach can be a new strategy to search supramolecular synthons and identify structures effectively and does have the potential to promote the development of energetic cocrystal by theoretical design.

In this work, we developed a new β-LiAlSi2O6/Mg2SiO4 glass-ceramic interlayer to join dense Si3N4 and porous Si3N4 ceramics for high-temperature applications. The microstructure and phases of the joint were investigated using systematic analysis methods and the mechanism for the interfacial bonding was proposed. The double crystalline phases of β-LiAlSi2O6 and Mg2SiO4 precipitated in the joint seam during the joining process, forming a novel glass-ceramic interlayer with high crystallinity. Due to the good wettability of liquid glass on porous Si3N4, a gradient and dense infiltration layer was formed in porous Si3N4 and reinforced it, which improved the mechanical strength of the whole joint. In this case, the shear strength of the joint reached 78 MPa, and it could still maintain 74 MPa up to 850 °C, which fully demonstrated the high-temperature resistance of the joint.

To meet demands of composite solid propellants, seeking a promising material as catalyst for the thermal decomposition of ammonium perchlorate (AP) has drawn attention. Herein, a commercially available nano sponge was used as the carbon source and a novel CuxO/carbonized nano sponge (CuxO/CNS) nanocomposite was successfully prepared via a facile precipitation method followed by a calcination process. CuxO/CNS nanocomposite was a simple sponge carbonization combined with CuxO nanoneedles grown directly on the surface of carbonized sponge substrate. Especially, CuxO nanoneedles looked like grass or leaf, dotted with carbon sponge skeleton. To further deeply evaluate the catalytic effect of CuxO/CNS nanocomposite on the thermal decomposition of AP, DSC technique was carried out. As expected, CuxO/CNS nanocomposite exhibited excellent catalytic effect on the thermal decomposition of AP. In a word, this finding provides a new insight into promising application of new catalysts in AP-based solid propellants.

Two-dimensional (2D) borophene has attracted tremendous interest due to its fascinating properties, which have potential applications in catalysts, energy storage devices, and high-speed transistors. In the past few years, borophene was theoretically predicted as an ideal electrode material for lithium-sulfur (Li-S) batteries because of its low-density, metallic conductivity, high Li-ion surface mobility, and strong interface bonding energy to polysulfide. But until now, borophene-based Li-S batteries have not yet been achieved in experiments due to the absence of a large-scale synthetic method of freestanding borophene nanostructures with a high enough structural stability, conductivity, and uniformity. Herein, we developed a low-temperature liquid exfoliation (LTLE) method to synthesize freestanding few-layer β12-borophene single-crystalline sheets with a P6¯m2 symmetry in tens of milligrams. The as-synthesized 2D sheets were used as the polysulfide immobilizers and electrocatalysts of Li-S batteries. The resulting borophene-based Li-S battery delivered an extralarge areal capacity of 5.2 mAh cm-2 at a high sulfur loading of 7.8 mg cm-2, an excellent rate performance of 8 C (@721 mAh g-1), and an ultralow capacity fading rate of 0.039% in 1000 cycles, outperforming commercial Li-ion batteries and many other 2D material-based Li-S batteries. Based on the density functional theory model, the excellent electrochemical performances of the borophene-based Li-S batteries should originate from the enormous enhancement of β12-borophene sheets for both the surface migration of the Li-ions and the adsorption energy of Li2Sn clusters. Our results thus demonstrate a great potential for scalable production of freestanding β12-borophene single-crystalline sheets in future high-performance Li-S batteries.

Electrospinning has been proven as a highly versatile fabrication method for producing nano-structured fibres with controllable morphology, of both the fibres themselves and the void structure of the mats. Additionally, it is possible to use heteroatom doped polymers or to include catalytic precursors in the electrospinning solution to control the surface properties of the fibres. These factors make it an ideal method for the production of electrodes and flow media for a variety of electrochemical devices, enabling reduction in mass transport and activation overpotentials and therefore increasing efficiency. Moreover, the use of biomass as a polymer source has recently gained attention for the ability to embed sustainable principles in the materials of electrochemical devices, complementing their ability to allow an increase in the use of renewable electricity via their application. In this review, the historical and recent developments of electrospun materials for application in redox flow batteries, fuel cells, metal air batteries and supercapacitors are thoroughly reviewed, including an overview of the electrospinning process and a guide to best practice. Finally, we provide an outlook for the emerging use of this process in the field of electrochemical energy devices with the hope that the combination of tailored microstructure, surface functionality and computer modelling will herald a new era of bespoke functional materials that can significantly improve the performance of the devices in which they are used.

In this work, 0.94(K0.48Na0.52)0.935Li0.065NbO3–0.06BaZrO3 (abbreviated as KNLN–0.06BZ) lead-free ceramics were prepared by conventional sintering (CS) and three-step sintering (TSS). The effects of sintering process on the microstructure and piezoelectric properties of ceramics were systematically studied. The result showed that, the ceramic prepared by TSS obtained higher density and better electrical properties compared to the ceramic prepared by CS. As we all know, the formation of defects will have a pinning effect on the domain switching. According to the results of impedance spectroscopy analysis, the ceramics prepared by TSS have fewer oxygen vacancies, which will make domain switching easier at an applied electric field, resulting in more excellent piezoelectric activity. The ceramics prepared by TSS with different sintering conditions showed different properties, but multiple phases may coexist in all ceramic samples according to the analysis of XRD, and the domain can adequately switch at an external electric field due to lower energy barrier at the phase boundary, resulting in high piezoelectric properties of ceramics. Hence, when the sintering condition was 1050 °C/0 min–1150 °C/5 min–1070 °C/20 h, the ceramic samples exhibited an optimal performance of ρ = 4.51 g/cm3, d33 ~ 258 pC/N, kp ~ 0.35, and TC ~ 328 oC. This superior result manifests that the KNLN–0.06BZ ceramic prepared by TSS is a promising ceramic for industrial application.

Laser surface modification technology is one of the most advanced technologies, which uses laser to modify the characteristics of the surface to offer superior performance for various industrial applications. In this study, laser surface hardening behavior of GM246 case iron was investigated. Result shows that excellent laser surface hardening of GM246 cast iron need low power density and scanning speed. With power of 2500 W, scanning speed of 300 mm/min and power density of 2500 W/cm2, the laser surface hardening of GM246 cast iron achieved the hardness of 790HV, which was 2-3 times higher than the hardness of base metal. Also, the depth of laser surface hardening case achieved 0.9 mm and the hardening case demonstrated three subzones.

Porphyria is a group of genetic photodermatoses that cause too much porphyrin to accumulate in the blood, skin, and liver, resulting in skin photosensitivity and damage, liver disease, or potential liver failure. Conventional detection methods include high-performance liquid chromatography and fluorescence spectrometry. However, these methods usually require complicated pretreatment and time-consuming processes. Therefore, efficient and fast detection of porphyria is urgently needed. Herein, we develop a molecular afterglow reporter-based sensing scheme for the detection of porphyrins in whole blood. The afterglow reporter can respond to the production of singlet oxygen (1O2) of porphyrins after light excitation, and the detection signals can be amplified through adjusting the amount of singlet oxygen and afterglow reporter molecules. Moreover, without the use of a real-time excitation source, afterglow signals can avoid the scattering and autofluorescence interference in biological samples, thereby reducing background noise. More importantly, we prove the applicability of the afterglow reporter in the quantitative detection of porphyrins in whole blood and demonstrate its great clinical potential.

Afterglow materials with long-lived emission after ceasing the excitation source have exhibited tremendous potential for various applications. However, the inherently dim afterglow emission makes i...

Accurate calculation of protein-protein binding free energy is of great importance in biological and medical science, yet it remains a hugely challenging problem. In this work, we develop a new strategy in which a screened electrostatic energy (i.e., adding an exponential damping factor to the Coulombic interaction energy) is used within the framework of the molecular mechanics/Poisson-Boltzmann surface area (MM/PBSA) method. Our results show that the Pearson correlation coefficient in the modified MM/PBSA is over 0.70, which is much better than that in the standard MM/PBSA, especially in the Amber14SB force field. In particular, the performance of the standard MM/PBSA is very poor in a system where the proteins carry like charges. Moreover, we also calculated the mean absolute error (MAE) between the calculated and experimental ΔG values and found that the MAE in the modified MM/PBSA was indeed much smaller than that in the standard MM/PBSA. Furthermore, the effect of the dielectric constant of the proteins and the salt conditions on the results was also investigated. The present study highlights the potential power of the modified MM/PBSA for accurately predicting the binding energy in highly charged biosystems.

Size-selected negatively-charged boron clusters (Bn−) have been found to be planar or quasi-planar in a wide size range. Even though cage structures emerged as the global minimum at B39−, the global minimum of B40− was in fact planar. Only in the neutral form did the B40 borospherene become the global minimum. How the structures of larger boron clusters evolve is of immense interest. Here we report the observation of a bilayer B48− cluster using photoelectron spectroscopy and first-principles calculations. The photoelectron spectra of B48− exhibit two well-resolved features at low binding energies, which are used as electronic signatures to compare with theoretical calculations. Global minimum searches and theoretical calculations indicate that both the B48− anion and the B48 neutral possess a bilayer-type structure with D2h symmetry. The simulated spectrum of the D2h B48− agrees well with the experimental spectral features, confirming the bilayer global minimum structure. The bilayer B48−/0 clusters are found to be highly stable with strong interlayer covalent bonding, revealing a new structural type for size-selected boron clusters. The current study shows the structural diversity of boron nanoclusters and provides experimental evidence for the viability of bilayer borophenes.

Here, we combine the piezoelectric wurtzite ZnO and the ferroelectric (111) BaTiO3 as a hexagonal closed-packed structure and report a systematic theoretical study on the ferroelectric behavior induced by the interface of ZnO/BaTiO3 films and the transport properties between the SrRuO3 electrodes. The parallel and antiparallel polarizations of ZnO and BaTiO3 can lead to intrinsic asymmetric ferroelectricity in the ZnO/BaTiO3 superlattice. Using first-principles calculations we demonstrate four different configurations for the ZnO/BaTiO3/ZnO superlattice with respective terminations and find one most favorable for the stable existence of asymmetric ferroelectricity in thin films with thickness less than 4 nm. Combining density functional theory calculations with non equilibrium Green's function formalism, we investigate the electron transport properties of SrRuO3/ZnO/BaTiO3/ZnO/SrRuO3 FTJ and SrRuO3/ZnO/BaTiO3/SrRuO3 FTJ, and reveal a high TER effect of 581% and 112% respectively. These findings provide an important insight into the understanding of how the interface affects the polarization in the ZnO/BaTiO3 superlattice and may suggest a controllable and unambiguous way to build ferroelectric and multiferroic tunnel junctions.

Asymmetric surface acoustic waves have been shown useful in separating particles and cells in many microfluidics designs, mostly notably sessile microdroplets. However, no one has successfully extracted target particles or cells for later use from such samples. We present a novel omnidirectional spiral surface acoustic wave (OSSAW) design that exploits a new cut of lithium niobate, 152 Y-rotated, to rapidly rotate a microliter sessile drop to ∼10 g, producing efficient multi-size particle separation. We further extract the separated particles for the first time, demonstrating the ability to target specific particles, for example, platelets from mouse blood for further integrated point-of-care diagnostics. Within ∼5 s of surface acoustic wave actuation, particles with diameter of 5 μm and 1 μm can be separated into two portions with a purity of 83% and 97%, respectively. Red blood cells and platelets within mouse blood are further demonstrated to be separated with a purity of 93% and 84%, respectively. These advancements potentially provide an effective platform for whole blood separation and point-of-care diagnostics without need for micro or nanoscale fluidic enclosures.

Strong photo-generated charge recombination within graphitic carbon nitride and the lack of suitable co-catalysts with selective high catalytic reaction activity have hindered the effective photocatalytic hydrogen peroxide production. In this work, a series of 2D co-catalyst nitrogen-doped graphenes with the different bond states of doped nitrogen were synthesized under modified synthetic conditions, resulting in different surface catalytic hydrogen peroxide generation activities. Electrochemical analysis proves that pyrrolic nitrogen doped in graphene plays an important role in improving two-electron-transferring reactions on the surface of nitrogen-doped graphene for hydrogen peroxide generation, which depresses further reduction of hydrogen peroxide into hydroxyl radicals. Benefiting from the synergistic role of improved charge separation and enhanced surface-selective reaction activity of the co-catalyst nitrogen-doped graphene, 2D/2D graphitic carbon nitride/nitrogen-doped graphene heterostructure composites produce 56.22 μmol hydrogen peroxide under visible light irradiation in 4 h, which is 2.77 times higher than the 20.28 μmol of pure graphitic carbon nitride.

To obtain nano-hydroxyapatite/poly(lactide-co-glycolide) (n-HA/PLGA) nanocomposite with superior mechanical properties, here, lignin was chosen to surface-modify for n-HA through co-precipitation method. The different reaction conditions of reaction time, phosphorus source, and the lignin addition amount were studied by fourier transformation infrared spectra, X-ray diffraction, the intuitionistic dispersion experiment, transmission electron microscope and thermal gravimetric analysis. The reaction mechanism and the best appropriate reaction condition were obtained. More importantly, the results of electromechanical universal tester, scanning electron microscope, differential scanning calorimetric analyzer, polarized optical microscopy and dynamic mechanical analysis confirmed that the obtained n-HA could greatly increase the mechanical strength of PLGA, owing to the excellent dispersion and promotion crystallization effect. Moreover, in vitro cell culture experimental results indicated that the n-HA surface-modified by lignin was favorable to improve the cell biocompatibility of PLGA. The study suggested that the introduction of lignin was a novel method to acquire a highly dispersed n-HA, which would provide a new idea to achieve the n-HA/PLGA nanocomposite as bone materials in future, and it would pave the way towards a new application of lignin in biomedical field.

The ethanol oxidation reaction is of critical importance to the commercial viability of direct ethanol fuel cell technology. However, owing to the poor C-C bond cleavage capability, almost all ethanol oxidation is incomplete and suffers from low selectivity toward the C1 pathway. Herein, under the support of theoretical calculations that the heterointerfaces between CoP and Pd can reduce the energy barrier of C-C bond cleavage, rich heterointerfaces in CoP/RGO-Pd hybrids were designed to improve ethanol electrooxidation performance through enhancing the selectivity toward the C1 pathway. The experimental results show that the faradaic efficiency of the C1 pathway of CoP/RGO-Pd hybrids is as high as 27.6%, surpassing most reported catalysts in the literature. As a result of this enhancement, CoP/RGO-Pd10 exhibits mass activity as high as 4597 mA·mg

TiO2 films were prepared by sol-gel method with butyl titanate, anhydrous ethanol, acetyl acetone and hydrochloric acid as raw materials, which were sintered at 380 °C and 530 °C respectively to obtain TiO2 films. XRD was used for analyzing the crystal structure of TiO2 film, and ImageJ software was used to detect the light transmittance of TiO2 film samples. The results show that the film sintered at 530 °C is brookite structure and the film sintered at 380 °C is anatase structure. The increase of sintering temperature is not conducive to the growth of TiO2 film grains. TiO2 films sintered at 380 °C have good light transmittance.

To obtain an ideal guided bone tissue regeneration (GBR) membrane, carboxylated bamboo fiber (BF) was designed to be introduced into the chitosan/nano-hydroxyapatite (CS/n-HA) system by ionic crosslinking to fabricate a novel BF/CS/n-HA composite membranes with different weight ratios. The formation mechanism of the BF/CS/n-HA ternary composite membrane and the effect of BF different contents on the BF/CS/n-HA composite membranes were studied by Fourier Transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), electromechanical universal tester, in vitro soaking in simulated body fluid (SBF). Results demonstrated that CS and modified BF would be ionic crosslinked by electrostatic interaction to form a three dimensional polyelectrolyte structure, meanwhile, n-HA was loaded in the polyelectrolyte structure by hydrogen bonding, which ensured the modified BF/CS/n-HA composite membranes to possess excellent tensile strength, compared to the CS/n-HA and untreated BF/CS/n-HA composite membrane. Moreover, the weight ratio of the modified BF/CS/n-HA of 2:6:2 displayed the highest tensile strength, whose tensile strength was improved by over two folds than that of CS/n-HA composite membrane owing to the most suitable proportion. In addition, in vitro simulated body fluids soaking results indicated that the modified BF/CS/n-HA composite membranes presented different degradation rates and could promote the apatite to deposit by investigating the weight loss, water absorption rate, SEM morphology observation and tensile strength reduce. All results revealed that the ionic crosslinking of carboxylated BF and CS was conducive to fabricate BF/CS/n-HA composite membrane with higher mechanical property, more suitable degradation and better bioactivity, in contrast with the CS/n-HA and untreated BF/CS/n-HA composite membranes, which had a great promising to obtain more satisfactory GBR membrane, moreover, the study would provide a new application for natural BF in the biomedical membrane field. In this manuscript, carboxylated bamboo fiber (BF) was designed to be introduced into the chitosan/nano-hydroxyapatite (CS/n-HA) system to fabricate a novel BF/CS/n-HA composite membranes with different weight ratios. The formation mechanism of the BF/CS/n-HA ternary composite membrane and the effect of modified BF different contents on the BF/CS/n-HA composite membranes were studied, and the main purpose of the study was to explore the feasibility of preparing the new BF/CS/n-HA composite membrane by ionic crosslinking. Results revealed that the ionic crosslinking of carboxylated BF and CS played an essential role in fabricating BF/CS/n-HA composite membrane with higher mechanical properties, more suitable degradation and better bioactivity. The study proved that the carboxylated BF/CS/n-HA composite membrane fabricated by ionic crosslinking had a great potential in obtaining more satisfactory GBR membrane in contrast with the CS/n-HA and untreated BF/CS/n-HA composite membranes, which would open up a new application for natural BF in the biomedical membrane field.

A protein Pascal triangle has been constructed as new type of supramolecular architecture by using the inducing ligand strategy that we previously developed for protein assemblies. Although mathematical studies on this famous geometry have a long history, no work on such Pascal triangles fabricated from native proteins has been reported so far due to their structural complexity. In this work, by carefully tuning the specific interactions between the native protein building block WGA and the inducing ligand R‐SL, a 2D Pascal‐triangle lattice with three types of triangular voids has been assembled. Moreover, a 3D crystal structure was obtained based on the 2D Pascal triangles. The distinctive carbohydrate binding sites of WGA and the intralayer as well as interlayer dimerization of RhB was the key to facilitate nanofabrication in solution. This strategy may be applied to prepare and explore various sophisticated assemblies based on native proteins., A Pascal‐triangle lattice is constructed by using a careful selection of protein building blocks with anisotropic shapes and two sets of carbohydrate binding sites. Moreover, the dynamic and exchangeable nature of non‐covalent interactions makes the further manipulation of 2D lattices to 3D crystals possible.

Intrinsic polar metals are rare, especially in oxides, because free electrons screen electric fields in a metal and eliminate the internal dipoles that are needed to break inversion symmetry. Here we use first-principles high-throughput structure screening to predict a new polar metal in bulk and thin film forms. After screening more than 1000 different crystal structures, we find that ordered BiPbTi2O6 can crystallize in three polar and metallic structures, which can be transformed between via pressure or strain. In a heterostructure of layered BiPbTi2O6 and PbTiO3, multiple states with different relative orientations of BiPbTi2O6 polar displacements, and PbTiO3 polarization, can be stabilized. At room temperature, the interfacial coupling enables electric fields to first switch PbTiO3 polarization and subsequently drive 180{\deg} change of BiPbTi2O6 polar displacements. At low temperatures, the heterostructure provides a tunable tunnelling barrier and might be used in multi-state memory devices., Comment: Full text is available free of charge at Communications Materials. 46 pages in total: 25 pages, 1 table and 7 figures in the main text; 23 pages, 2 tables, and 11 figures in the supplementary materials

We developed a luminescence lifetime-based nanothermometer with a single-exponential luminescence decay in the ∼s time scope via a photochemical reaction. The luminescence lifetime imaging in vivo can be performed on an EMCCD and consumer-grade camera, which significantly reduces the technical threshold of luminescence lifetime imaging.

La-doped boron nanoclusters have received considerable attention due to their unique structures and bonding. Inspired by recent experimental observations of the inverse sandwich D8h La2B8 (1) and triple-decker C2v La3B14− (2) and based on extensive global searches and first-principles theory investigations, we present herein the possibility of the perfect cubic La-doped boron clusters Oh La6&[La@B24]+ (3, 1A1g) and Oh La6&[La@B24] (4, 2A2g) which appear to be the embryos of the metallic one-dimensional La10B32 (5) nanowire, two-dimensional La3B10 (6) nanosheet, and three-dimensional LaB6 (7) nanocrystal, facilitating a bottom-up approach to build cubic lanthanide boride nanostructures from gas-phase clusters. Detailed molecular orbital and bonding analyses indicate that effective (d–p)σ, (d–p)π and (d–p)δ covalent coordination interactions exist in La6&[La@B24]+/0 (3/4) clusters, while the 1D La10B32 (5), 2D La3B10 (6), and 3D LaB6 (7) crystals exhibit mainly electrostatic interactions between the trivalent La centers and cubic B24 frameworks, with weak but discernible coordination contributions from La (5d) ← B (2p) back-donations. The IR and Raman spectra of La6&[La@B24]+/0 (3/4) and band structures of La10B32 (5) and La3B10 (6) are computationally simulated to facilitate their future characterizations.

The newly discovered cage-like borospherene D2d B40 with two η6-B6 hexagons and four η7-B7 heptagons on the surface may serve as an effective multi-dentate ligand to coordinate transition metals. Based upon extensive density functional theory calculations, we present herein the possibility of the exohedral complex series (C6H6Cr)n&B40 (n = 1–6) with n Cr centres sandwiched between the central η6/7-B40 unit and n planar η6-C6H6 ligands. C6H6Cr fragments in (C6H6Cr)n&B40 occupy the η6-B6 hexagonal coordination site atop the B40 cage first, the four neighboring η7-B7 heptagons on the waist next, and finally the η6-B6 hexagon at the bottom, forming a multinuclear complex series effectively stabilized by n C6H6Cr fragments. The two η6-B6 hexagons and four η7-B7 heptagons on the spherical surface of B40 can be practically viewed as six independent coordination sites to coordinate Cr centers with almost the same coordination energies. Detailed bonding analyses indicate that the eclipsed C2v C6H6Cr&B40 (1-1) possesses a coordination bonding pattern similar to that of dibenzenechromium, with the B40 ligand inheriting the σ + π double delocalization bonding pattern of the parent borospherene. The IR, Raman, and UV–vis absorption spectra of C2v C6H6Cr&B40 (1-1) are theoretically simulated to facilitate its future experimental characterization.

The effects of tempering temperatures on the microstructure and mechanical properties of the simulated coarse-grain heat-affected zone (CGHAZ) and inter-critical heat-affected zone (ICHAZ) were investigated for a high-strength–high-toughness combination marine engineering steel. The results demonstrate that the microstructure of the simulated CGHAZ and ICHAZ after tempering is characterized by tempering sorbites and coarse grain in the simulated CGHAZ. As tempering temperature increases, the tensile strength of the simulated CGHAZ and ICHAZ decreases and the Charpy absorbed energy of the simulated ICHAZ at − 50 °C increases remarkably, but the impact toughness of the simulated CGHAZ is not improved. After tempering at 550 °C, the coarse flake carbides, which distribute at the prior austenite grain and martensite lath boundaries, deteriorate the impact toughness of the simulated CGHAZ. With the increase in tempering temperature, the morphology and the size of the carbides gradually change from coarse flake to fine granular, which is beneficial to the improvement of impact toughness. However, the coarse-grain size of the simulated CGHAZ and the M23C6-type carbide precipitated along the grain boundaries weakens the enhancing effect of carbides on impact toughness.

The well control over the cell-nanoparticle interaction can be of great importance and necessity for different biomedical applications. In this work, we propose a new and simple way (i.e., polymeric tether) to tuning the interaction between nanoparticles and cell membranes by dissipative particle dynamics simulations. It is found that the linked nanoparticles (via polymeric tether) can show some cooperation during the cellular uptake and thereby have a higher wrapping degree than the single nanoparticle. The effect of the property of the polymer on the wrapping is also investigated, and it is found that the length, rigidity, and hydrophobicity of the polymer play an important role. More interestingly, the uptake of linked nanoparticles could be adjusted to the firm adhesion via two rigid polymeric tethers. The present study may provide some useful guidelines for novel design of functional nanomaterials in the experiments.

Boron and metal-doped boron nanoclusters possess unique fluxional behaviors in dynamics. Detailed bonding analyses performed in this work indicate that, similar to the experimentally observed B2-[Ta@B18]− (1), the theoretically predicted tubular molecular rotors B3-[Ta@B18] (2) and B4-[Ta@B18]+ (3) possess typical fluxional 4c–2e and 3c–2e σ-bonds atop the Ta-centered [Ta@B18] double-ring tube between the Bn unit (n = 3, 4) and upper B9 ring, unveiling the fluxional bonding nature of the Bn-[Ta@B18]q complex series (n = 2–4, q = n − 3) which follow the 18-electron rule in different charge states. Chiral conversions via pseudo-rotations are observed in the fluxional processes between the Bn unit (n = 3, 4) and Ta-centered [Ta@B18] double-ring tube.

Inspired by recent discoveries of alkaline-earth octacarbonyls and based on extensive first-principles theory investigations, we predict herein the possibility of perfect cube-like alkali octacarbonyls M(CO) 8 − (Oh, 3A1g) (1) (M = K, Rb) which satisfy the 18-electron rule in an octacoordinate cubic field with (n − 1)d-orbital participation of alkali metal center playing an important role in M–CO coordination interaction. The slightly elongated neutral M(CO)8 (D4h, 2B1g) (3) turn out to be similar with the experimentally observed Ba(CO) 8 + monocation in an octacoordinate tetragonal field. Detailed orbital analyses indicate that, similar to neutral alkaline-earth octacarbonyls, M(CO) 8 − monoanions possess the superatomic electronic configuration of S2P6D8F2, with the alkali–CO coordination interaction mainly originating from M(dπ) → (CO)8(π*) backdonations which result in strong red shifts of the C–O stretching frequencies relative to free CO.

Detailed molecular orbital and bonding analyses reveal the existence of both fluxional σ- and π-bonds in the global minima CsB182- (1) and Cs MB18 (3) and transition states CsB182- (2) and CsMB18- (4) of B182- dianion and MB18- monoanions (M = K, Rb, and Cs). It is the fluxional bonds that facilitate the fluxional behaviors of the quasi-planar B182- and half-sandwich MB18- which possess energy barriers smaller than the difference of the corresponding zero-point corrections. © 2019 Wiley Periodicals, Inc.

Regular and uniform-shaped BaTiO 3 microplates have been prepared using a modified topochemical microcrystal conversion (TMC) method. The BaTiO 3 platelets are approximately 10 µm × 10 µm × 0.5 µm in rectangular shape. The precursor has a significant effect on the shape of BaTiO 3 microplates. In aurivillius precursors, the perovskite blocks sandwiched by [Bi 2 O 2 ] slabs are misaligned along c axis, which will cause exfoliation during TMC. When using Bi 4 Ti 3 O 12 or polycrystalline BaBi 4 Ti 4 O 15 as a precursor, exfoliation occurs, which leads to small BaTiO 3 particles. However, single-crystalline BaBi 4 Ti 4 O 15 precursor exhibits continuity within the platelets. The continuity of BaBi 4 Ti 4 O 15 inhibits the exfoliation of BaTiO 3 microplates. The well-shaped BaTiO 3 microplates derived from the single-crystalline BaBi 4 Ti 4 O 15 precursor are proved to be suitable for textured ceramics.

The exfoliation of monolayer borophenes from substrates is deemed a prerequisite for their further applications. Detailed density functional theory calculations performed herein indicate that Li/Mg adatoms evenly distributed on a borophene tend to transform the interaction between borophene and the Ag(111) substrate into van der Waals-like interaction and help to separate them, making the exfoliation of borophenes from substrates much easier. It is also possible for Li/Mg atoms to intercalate below borophene from borophene edges to separate borophene from the substrate. The results obtained in this work may facilitate the exfoliation of borophenes from metal substrates in future experiments.

LiCrO2 and NaCrO2 have been well-studied as cathode materials in lithium and sodium ion batteries, while the studies on LiCrS2 and NaCrS2 are relatively rare. In this work, a comparative study on the electronic structures and redox reactions in oxides (LiCrO2, NaCrO2) and sulfides (LiCrS2, NaCrS2) is performed. A first-principles method has been used to calculate the Bader charge transfer, the electronic structures and the magnetic moments during the entire delithiation or desodiation process. The Bader charge analysis suggests that all the S, O and Cr ions in LiCrX2 and NaCrX2 participate in the redox reactions, where the loss of electrons of S ions is clearly larger than that of O ions. Besides, the redox processes of Cr ions are of much less significance. It is noted that, in the sulfides, Cr ions even gain a small portion of electrons rather than losing electrons during the extraction of Li/Na ions. All the charge transfer happens between the S-3p/O-2p and the Cr-3d bands. The redox reactions of O or S ions originate from the energy levels of O/S being pushed towards/across the Fermi surface due to the strong p–d hybridization.

Carbon and boron can mix to form numerous two-dimensional (2D) compounds with strong covalent bonds, yet very few possess a bandgap for functional applications. Motivated by the structural similarity between graphene and recently synthesized borophene, we propose a new family of semiconducting boron carbide monolayers composed of B4C3 pyramids and carbon hexagons, denoted as (B4C3)m(C6)n (m, n are integers) by means of the global minimum search method augmented with first-principles calculations. These monolayers are isoelectronic to graphene yet exhibit increased bandgaps with decreasing n/m, due to the enhanced localization of boron multicenter bonding states as a consequence of the electronic transfer from boron to carbon. In particular, the B4C3 monolayer is even more stable than the previously synthesized BC3 monolayer and has a direct bandgap of 2.73 eV, with the promise for applications in optical catalysis and optoelectronics. These results are likely to inform the on-going effort on the design of semiconducting 2D materials based on other light elements.

Efficient anchoring of transitional metals on supporting materials with well-exposed metal atoms and tuned chemical bonds between them is crucially important for the design of high-performance electrocatalysts. In this study, we adopted a strategy of using defective carbon nanotubes to synthesize holey graphene oxide with tunable basal plane hole size. Via the in situ formation of cobalt clusters during the process of doping of nitrogen into holey graphene oxide, the obtained composite showed strong chemical bonding of highly exposed cobalt with nitrogen and carbon on the nitrogen-doped holey graphene. It was found that the basal plane hole of graphene was beneficial for the deposition of cobalt; detailed analysis showed that rich defects on the basal plane favored the doping of pyridinic nitrogen and graphitic nitrogen and enhanced the chemical bonding of cobalt with nitrogen; this improved the four-electron transfer selectivity of the ORR; thus, the effectively enhanced catalytic activity of composites was comparable to those of the commercial Pt/C catalyst; moreover, these composites exhibited superior stability than the commercial Pt/C catalyst.

As the first all-boron fullerene observed in experiments, cage-like borospherene B40 has attracted considerable attention in recent years. However, B40 has been proved to be chemically reactive and tends to coalesce with one another via the formation of covalent bonds. We explore herein the possibility of low-dimensional functional networks of B40 with effective transition-metal intercalations. We find that the four equivalent B7 heptagons on the waist of each B40 can serve as effective ligands to coordinate various transition metal centers in exohedral motifs. The intercalated metal atoms entail these networks with a variety of intriguing properties. The two-dimensional (2D) Cr2B40 network is a ferromagnetic metal while the 2D Zn2B40 network becomes semiconducting. In contrast, other 2D M2B40 (M = Sc, Ti, V, Mn, Fe, Co, Ni and Cu) networks and 1D CrB40 belong to nonmagnetic metals. The 3D Cr3B40 network is a magnetic metal. This work presents the viable possibility of assembling Mn&B40 metalloborospherenes into stable functional nanomaterials via effective transition-metal intercalations with potential applications in electronic and spintronic devices.

Lanthanide-boron binary clusters possess interesting structures and bonding which may provide insights into designing new boride nanomaterials. Inspired by the recently discovered mono-decker inverse sandwich D9h La2B9- (1A'1) (1) and based on the extensive first-principles theory calculations, we predict herein the possible existence of a series of bi-decker inverse sandwich di-lanthanide boron complexes including D9d La2[B18] (3A1g) (2), D9d La2[B18]2- (1A1g) (3), and C2h La2[B2@B18] (1Ag) (4) which all contain a tubular Bn ligand (n = 18, 20) sandwiched by two La atoms at the two ends. In these novel clusters, La2[B2@B18] (4) as a tubular molecular rotor with the smallest core-shell structure reported to date in boron-based nanoclusters possesses a B2-bar rotating constantly and almost freely inside the B18 tube around it at room temperature. Detailed bonding analyses indicate that these complexes are stablized by effective (d-p)σ, (d-p)π, and (d-p)δ coordination interactions between the La centers and Bn bi-decker ligand. Six multi-center fluxional σ-bonds between the B2-core and B18 tube in La2[B2@B18] (4) are found to be responsible for its unique fluxional behaviors. The IR and Raman spectra of the concerned species are simulated to facilitate their experimental characterization.

Two-dimensional (2D) borophene is predicted as an ideal electrode material for lithium sulfur (Li-S) batteries because of low-density, metallic conductivity, high Li-ion surface mobility and strong interface bonding energy to polysulfide. But until now, 2D borophene-based Li-S batteries have not yet been achieved due to the absence of massive synthesis method. Herein, we developed a novel low-temperature liquid exfoliation (LTLE) method for scalable synthesis of single crystalline 2D few-layer β12-borophene sheets with a \(P\stackrel{-}{6}m2\) symmetry. The as-synthesized 2D sheets were used as the polysulfide immobilizers and electrocatalysts of Li-S batteries for the first time. The resulting Li-S cells employing borophene sheets delivered a strikingly high areal capacity of 5.2 mAh cm− 2 at a high sulfur loading of 7.8 mg cm− 2 with an ultralow capacity fading rate (0.039 % per cycle) in 1000 cycles, outperforming most of the Li-S batteries employing other 2D materials. Under the help of few-layer β12-borophene, their high-activity behaviors should be attributed to the significant enhancement of both the Li-ion’s surface migration and the adsorption energy for Li2Sn clusters based on density functional theory (DFT) models. Our research reveals great potential of 2D β12-borophene sheets in future high-performance Li-S batteries.

B-C binary monolayers and fullerenes (borafullerenes) have received considerable attention in recent years. Inspired by the newly reported B4C3 semiconducting boron carbide monolayer isovalent to graphene (Tian et al., Nanoscale, 2019, 11, 11099), we predict herein at density functional theory level a new class of borafullerenes (1–8) following the isolated B4C3 hexagonal pyramid rule. The spherically aromatic borafullerenes C5h B20C35 (1), C5 B20C45 (2), C5h B20C55 (3), and C5 B20C65 (4) isovalent to C50, C60, C70, and C80, respectively, possess five isolated B4C3 hexagonal pyramids evenly distributed on the waist around the C5 molecular axis, while S10 B40C50 (5), C5 B40C60 (6), S10 B40C70 (7), and C5 B40C80 (8) encompass ten isolated B4C3 pyramids symmetrically distributed on the cage surface. Detailed orbital and bonding analyses indicate that these borafullerenes follow similar σ and π-bonding patterns with their fullerene analogues, with three delocalized 7c-2e π bonds forming a local π-aromatic system over each isolated B4C3 hexagonal pyramid. The calculated formation energies of the (B4C3)nC60-6n (n = 1–5) series isovalent to C60 appear to increase almost linearly with the number of isolated B4C3 pyramids in the system. The IR, Raman, and UV-vis spectra of the prototypical B20C45 (2) are theoretically simulated to facilitate its future spectral characterization.

The W1Mo1-NG dual-atom catalyst enables Pt-like activity and ultrahigh stability for hydrogen evolution reaction., Single-atom catalysts (SACs) maximize the utility efficiency of metal atoms and offer great potential for hydrogen evolution reaction (HER). Bimetal atom catalysts are an appealing strategy in virtue of the synergistic interaction of neighboring metal atoms, which can further improve the intrinsic HER activity beyond SACs. However, the rational design of these systems remains conceptually challenging and requires in-depth research both experimentally and theoretically. Here, we develop a dual-atom catalyst (DAC) consisting of O-coordinated W-Mo heterodimer embedded in N-doped graphene (W1Mo1-NG), which is synthesized by controllable self-assembly and nitridation processes. In W1Mo1-NG, the O-bridged W-Mo atoms are anchored in NG vacancies through oxygen atoms with W─O─Mo─O─C configuration, resulting in stable and finely distribution. The W1Mo1-NG DAC enables Pt-like activity and ultrahigh stability for HER in pH-universal electrolyte. The electron delocalization of W─O─Mo─O─C configuration provides optimal adsorption strength of H and boosts the HER kinetics, thereby notably promoting the intrinsic activity.

Nowadays, environmental problems such as petroleum resources exhaustion, pollution and global warming are in ceaseless aggravation. Consequently, vegetable oil becomes one of the most important resources due to its cheapness, easily availability and environmental regeneration. In this study, a series of sustainable polyurethanes based on epoxy soybean oil modified by different contents of 3,13-dimethyhydroxysilyl double-decker phenylsilsesquioxane [DDSQ(Me)OH] have been prepared. Polyol prepared with epoxy soybean oil has effectively replaced the petroleum-based polyol and the DDSQ(Me)OH performed as chain extender together with 1,4-butanediol (BDO). The structure of DDSQ(Me)OH was verified by 1H NMR and MALDI–TOF–MS. The structure and properties of sustainable polyurethanes were characterized by FTIR, DSC, TGA, SEM, tensile test and static contact angle. TGA demonstrated that hybrid polyurethanes were thermally stable due to the covalent incorporation of DDSQ(Me)OH in polymer main chain, the 5% weight loss temperatures (Td5) of hybrid polyurethane can be 21 °C higher than pure PU. DSC revealed the improved glass transition temperature (Tg) of polyurethanes, and the Tg can be 12.4 °C improved compared with pure polyurethane. SEM showed that the aggregation of DDSQ(Me)OH has dispersed homogeneously in the hybrid polyurethanes matrix. The results of the static contact angle revealed that with the increase of DDSQ(Me)OH content, the surface hydrophobicity has been enhanced significantly, and the static contact angle of water for hybrid polyurethanes can be up to about 110.2°.

Based on detailed bonding analyses on the fluxional behaviors of planar B19- , tubular Ta@B20- , and cage-like B39- , we propose the concept of fluxional bonds in boron nanoclusters as an extension of the classical localized bonds and delocalized bonds in chemistry. © 2018 Wiley Periodicals, Inc.

Vegetable oil-based polyurethanes were synthesized using castor oil (CO) as feedstock, which were characterized by their environmental friendly and renewable properties. Aiming to compensate for shortcomings of these materials, a series of polyurethane/polyhedral octaphenylsilsesquioxane (OPS) hybrids with different OPS contents were prepared by physical mixing in the solutions. Thereafter?chemical structure?morphology and thermal properties of hybrids were characterized through Fourier transform infrared spectrometer (FTIR), scanning electron microscope (SEM), differential scanning calorimetry (DSC), thermal gravimetric analyzer (TGA), tensile test techniques and static contact angle. The results show that the hybrid polyurethanes display both enhanced glass transition temperatures (Tg), initial decomposition temperature (Td5) and tensile strength with low OPS contents. While with high contents?these values decline with the severe aggregation of nano-particles as shown in the SEM images. Meanwhile, the hybrid polyurethanes displayed enhanced surface hydrophobicity as the contact angle with water revealed

Brain-inspired computing architectures attempt to emulate the computations performed in the neurons and the synapses in the human brain. Memristors with continuously tunable resistances are ideal building blocks for artificial synapses. Through investigating the memristor behaviors in a La0.7Sr0.3MnO3/BaTiO3/La0.7Sr0.3MnO3 multiferroic tunnel junction, it was found that the ferroelectric domain dynamics characteristics are influenced by the relative magnetization alignment of the electrodes, and the interfacial spin polarization is manipulated continuously by ferroelectric domain reversal, enriching our understanding of the magnetoelectric coupling fundamentally. This creates a functionality that not only the resistance of the memristor but also the synaptic plasticity form can be further manipulated, as demonstrated by the spike-timing-dependent plasticity investigations. Density functional theory calculations are carried out to describe the obtained magnetoelectric coupling, which is probably related to...

The photoelectric effect in semiconductors is the main mechanism for most modern optoelectronic devices, in which the adequate bandgap plays the key role for acquiring high photoresponse. Among numerous material categories applied in this field, the complex oxides exhibit great possibilities because they present a wide distribution of band gaps for absorbing light with any wavelength. Their physical properties and lattice structures are always strongly coupled and sensitive to light illumination. Moreover, the confinement of dimensionality of the complex oxides in the heterostructures can provide more diversities in designing and modulating the band structures. On the basis of this perspective, we have chosen itinerary ferromagnetic SrRuO3 as the model material, and fabricated it in one-unit-cell thickness in order to open a small band gap for effective utilization of visible light. By inserting this SrRuO3 monolayer at the interface of the well-developed two-dimensional electron gas system (LaAlO3/SrTiO3...

Reduced graphene oxide (RGO) has been prepared by a hydrothermal reduction method to explore the effects of reaction temperature on its permittivity and electromagnetic absorption (EA) performance. This study shows that by controlling the oxygen functional groups on the RGO surface it is also possible to obtain an ideal EA performance without any other decorated nanomaterials.

Shortly after the discovery of all-boron fullerenes D2d B40−/0 (borospherenes), the first axially chiral borospherenes C3/C2 B39− were characterized in experiments in 2015. Based on extensive global minimum searches and first-principles theory calculations, we present herein two new axially chiral members to the borospherene family: the aromatic cage-like C2 B34(1) and C2 B35+(2). Both B34(1) and B35+(2) feature one B21 boron triple chain on the waist and two equivalent heptagons and hexagons on the cage surface, with the latter being obtained by the addition of B+ into the former at the tetracoordinate defect site. Detailed bonding analyses show that they follow the universal bonding pattern of σ + π double delocalization, with 11 delocalized π bonds over a σ skeleton. Extensive molecular dynamics simulations show that these borospherenes are kinetically stable below 1000 K and start to fluctuate at 1200 K and 1100 K, respectively. The IR, Raman, and UV-vis spectra of 1 and 2 are computationally simulated to facilitate their experimental characterization.

Transition-metal doping leads to dramatic structural changes and results in novel bonding patterns in small boron clusters. Based on the experimentally derived mono-ring planar C9v Ta©B92- (1) and extensive first-principles theory calculations, we present herein the possibility of high-symmetry double-ring tubular D9d Ta@B183- (2) and C9v Ta2@B18 (3) and triple-ring tubular D9h Ta2@B27+ (4), which may serve as embryos of single-walled metalloboronanotube α-Ta3@B48(3,0) (5) wrapped up from the recently observed most stable free-standing boron α-sheet on a Ag(111) substrate with a transition-metal wire (-Ta-Ta-) coordinated inside. Detailed bonding analyses indicate that, with an effective dz2-dz2 overlap on the Ta-Ta dimer along the C9 molecular axis, both Ta2@B18 (3) and Ta2@B27+ (4) follow the universal bonding pattern of σ + π double delocalization with each Ta center conforming to the 18-electron rule, providing tubular aromaticity to these Ta-doped boron complexes with magnetically induced ring currents. The IR, Raman, and UV-vis spectra of 3 and 4 are computationally simulated to facilitate their future experimental characterization.

Copper-carbon alloy films have been applied in barrier-less Cu metallization as seed layers for improving the thermal stabilities. The effect of the deposition temperature on the microstructure and properties of C-doped Cu films on Si substrates was investigated. The films were prepared by ion beam-assisted deposition at various deposition temperatures by co-sputtering of Cu and graphite targets. No inter-diffusion between Cu and Si was observed in Cu(C) films throughout this experiment, because XRD patterns corresponding to their deep-level reaction product, namely, Cu 3 Si, were not observed in XRD patterns and EDS results of Cu(C) films. Amorphous carbon layer and SiC layer were found in the interface of Cu(C) as-deposited films when deposition temperature rose to 100 °C by TEM, high-resolution image and Fourier transformation pattern. The Cu(C) films deposited at 100 °C had the best thermal stabilities and the lowest electrical resistivity of 4.44 μW cm after annealing at 400 °C for 1 h. Cu agglomeration was observed in Cu(C) alloy films with deposition temperatures of 200, 300 and 400 °C, and the most serious agglomeration occurred in Cu(C) films deposited at 200 °C. Undesired Cu agglomeration resulted in a sharp increase in the resistivity after annealing at 300 °C for 1 h. The deposition temperature of 100 °C reflected the superior thermal stabilities of Cu(C) seed layers compared with those of other layers.