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To explore the evolution mechanism of multistage machining processes and torsional fatigue behaviour based on strain energy for the first time and provide process optimization of axis parts of low-alloy medium-carbon steel for service performance, four multistage machining processes were applied to the 45CrNiMoVA steel, including the rough turning process (RT), RT + the finish turning process (FRT), FRT+ the grinding process (GFRT) and RT+ the finish turning process on dry cutting condition (FRT0). The result showed that the FRT process’s average low-cycle torsional fatigue life increased by 50% when it evolved from the RT process. The lower surface roughness of Ra 1.3 μm caused the total strain energy to increase by 163.8 Pa mm/mm instead of the unchanged strain energy density, and the crack feature evolved from some specific bulges to flat shear plane characteristics. When the GFRT process evolved from the FRT process, its average fatigue life increased by 1.45 times, compared with the RT process. Plastic strain amplitude decreased by 21%, and the strain energy density decreased by 4% due to more considerable compressive residual stress (-249 MPa). Plastic deformation layer depth had a consistent tendency with surface roughness. In this paper, surface integrity evolutions on cyclic characteristics and fatigue behaviour have also been explained. A fatigue life prediction model based on the energy method for machined surface integrity is proposed.

CePO4: Tb3+ nanorods were successfully obtained via a simple hydrothermal method and combined with carbon dots (CDs) to obtain CDs@CePO4: Tb3+ nanorods. Due to the combination of CDs, the emission intensity of CDs@CePO4: Tb3+ nanorods has increased about 92 times, compared with that of CePO4: Tb3+ nanorods. The combination of CDs and CePO4: Tb3+ nanorods was confirmed by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and so on. The mechanism of luminescence enhancement might be attributed to some aspects: the formation of hexagonal phase results in the increase of crystal field symmetry, and the energy transfer among CDs, Ce3+ and Tb3+ ions, which leads to the Tb3+ ions in CDs@CePO4: Tb3+ nanorods obtaining more excited energy and less non-radiative attenuation comparing to CePO4: Tb3+ nanorods. The luminescence enhancement strategy through combination of CDs would provide a simple and effective approach for other rare earth ions doped luminescent materials.

The complex micromechanical response among grains remains a persistent challenge to understand the deformation mechanism of titanium alloys during cold rolling. Therefore, in this work, a multiscale crystal plasticity finite element method of dual-phase alloy was proposed and secondarily developed based on LS-DYNA software. Afterward, the texture evolution and slip mode of a Ti-5.5Mo-7.2Al-4.5Zr-2.6Sn-2.1Cr alloy, based on the realistic 3D microstructure, during cold rolling (20% thickness reduction) were systematically investigated. The relative activity of the 2 ¯ 0>{0001} slip system in the α phase gradually increased, and then served as the main slip mode at lower Schmid factor ( 2 ¯ 3>{10 1 ¯ 1} slip system to the overall plastic deformation was relatively limited. For the β phase, the relative activity of the {110} slip system showed an upward tendency, indicating the important role of the critical resolved shear stress relationship in the relative activity evolutions. Furthermore, the abnormally high strain of very few β grains was found, which was attributed to their severe rotations compelled by the neighboring pre-deformed α grains. The calculated pole figures, rotation axes, and compelled rotation behavior exhibited good agreement to the experimental results.

In this study, Co2P/CoP hybrid nanoparticles (NPs) imbedded on the surface of core-shell metal-organic frameworks (MOFs) derived three-dimensional N, P co-doped graphitized carbon (Co2P/CoP@NPGC) are prepared via direct pyrolysis of P-containing MOF precursors. P dopant dosage is tailored to adjust active sites and crystalline phases of Co2P/CoP@NPGC. The active Co2P and CoP NPs and the synergistic effect from the Co-Nx/C and Co-P/C active sites and porous NPGC make the dominant contributions to the ORR/OER. For ORR, the half-wave potential of Co2P/CoP@NPGC-1 is 0.93V, which is superior to that of Pt/C (E1/2 = 0.875 V). As for OER, Co2P/CoP@NPGC-1 displays a lower overpotential (ƞ = 340 mV) compared to RuO2 (ƞ = 380 mV, at 10 mA cm-2). The Co2P@CoOOH heterojunction guarantees intrinsic conductivity. Furthermore, doping with N and P can modify the surface electronic structure of catalyst to lower the energy of oxygen adsorption and dissociation, which are beneficial to enhance the ORR and OER activity. Additionally, its bifunctional activity parameter (ΔE) for ORR and OER is only 0.64 V, which is lower than that of Pt/C and RuO2 (0.76 V). Therefore, this work proposes a new sight into constructing a competitive core-shell MOFs derived electrocatalyst for ORR/OER.

Non-noble metal catalyst with high catalytic activity and stability towards oxygen reduction reaction (ORR) is critical for durable bioelectricity generation in air-cathode microbial fuel cells (MFCs). Herein, nitrogen-doped (iron-cobalt alloy)/cobalt/cobalt phosphide/partly-graphitized carbon ((FeCo)/Co/Co2P/NPGC) catalysts are prepared by using cornstalks via a facile method. Carbonization temperature exerts a great effect on catalyst structure and ORR activity. FeCo alloys are in-situ formed in the catalysts above 900 °C, which are considered as the highly-active component in catalyzing ORR. AC-MFC with FeCo/Co/Co2P/NPGC (950 °C) cathode shows the highest power density of 997.74 ± 5 mW m−2, which only declines 8.65% after 90 d operation. The highest Coulombic efficiency (23.3%) and the lowest charge transfer resistance (22.89 Ω) are obtained by FeCo/Co/Co2P/NPGC (950 °C) cathode, indicating that it has a high bio-electrons recycling rate. Highly porous structure (539.50 m2 g−1) can provide the interconnected channels to facilitate the transport of O2. FeCo alloys promote charge transfer and catalytic decomposition of H2O2 to •OH and •O2−, which inhibits cathodic biofilm growth to improve ORR durability. Synergies between metallic components (FeCo/Co/Co2P) and N-doped carbon energetically improve the ORR catalytic activity of (FeCo)/Co/Co2P/NPGC catalysts, which have the potential to be widely used as catalysts in MFCs.

Thermochemical energy storage (TCES) is proving to be a promising option for residential energy storage applications. Many studies have indicated that the pressure drop and heat and mass transfer efficiency of the reactor are two key determinants with TCES technologies. In this paper, net-packed method is used to carry out thermal performance enhancement study for a thermochemical reactor. Compared with and the without net packed methods, copper mesh shows better thermal performance. The copper mesh method of zeolite achieved maximum temperature rise of 38.6 °C, which is 4.4 °C and 2.3 °C higher than that of the non-packed and aluminum mesh, respectively. The pressure drop is reduced by 28.1% and higher water adsorption has been realized. In addition, the energy storage density of 784.4 kJ/kg and thermal efficiency of 38.2% are obtained with the copper mesh. These are 1.6 and 2.4 times the results of the non-packed tests respectively.

Carbon nanomaterials have proven their wide applicability in molecular separation and water purification techniques. Here, an unzipped carbon nanotubes (CNT) embedded graphene oxide (GO) membrane (uCNTm) is reported. The multiwalled CNTs were longitudinally cut into multilayer graphene oxide nanoribbons by a modified Hummer method. To investigate the varying effects of different bandwidths of unzipped CNTs on their properties, four uCNTms were prepared by a vacuum-assisted filtration process. Unzipped-CNTs with different bandwidths were made by unzipping multiwalled CNTs with outer diameters of 0-10, 10-20, 20-30, and 30-50 nm and named uCNTm-1, uCNTm-2, uCNTm-3, and uCNTm-4, respectively. The uCNTms exhibited good stability in different pH solutions, and the water permeability of the composite membranes showed an increasing trend with the increase of the inserted uCNTm's bandwidth up to 107 L·m-2·h-1·bar-1, which was more than 10 times greater than that of pure GO membranes. The composite membranes showed decent dye screening performance with the rejection rate of methylene blue and rhodamine B both greater than 99%.

The entrainment coefficient of the pure plume, the ratio of the radial velocity of the entraining fluid at the edge of the plume to the axial velocity, is characterized by a remarkable deviation from the actual value in references. To a turbulent flow with Gaussian profiles, the entrainment coefficient is accepted in a considerably wide range from 0.07 to 0.11 for pure plumes. In this study, the entrainment coefficient of a pure plume is determined by analyzing the stratified interface formed between fresh water and a buoyant fluid in a confined space. The interface position is determined using digital image processing while conducting salt-water experiments. The displacement of the virtual origin of the real plume is added to the original heights of the confined space and stratified interface because the plume in the laboratory is from a source of finite area rather than from a point. The two virtual source position determination methods are compared; the one where the ratio of the displacement of the virtual origin to the nozzle diameter is related only to the source parameter Γ is selected for the theoretical analysis. The experimental data of the source parameter Γ and corresponding entrainment coefficients indicate that the α value of the pure plume is 0.09251 when using the interpolation method. This value is validated through displacement experiments on a pure plume created by supplying salt water through the nozzle in a laboratory. Further, the entrainment coefficient of a turbulent jet is determined based on the stratified interface behavior in a confined space; the experimental results support the speculation that the entrainment coefficient of the pure jet should be 0.057. The experimental data of the entrainment coefficient α plotted against parameter Γ in the available literature are compared with those estimated from semi-empirical equations with two asymptotic values suggested in this paper.

High-entropy oxides (HEOs) and medium-entropy oxides (MEOs) are new types of single-phase solid solution materials. MEOs have rarely been reported as positive electrode material for sodium-ion batteries (SIBs). In this study, we first proposed the concept of the application of MEOs in SIBs. P2-type 3-cation oxide Na2/3Ni1/3Mn1/3Fe1/3O2 (NaNMF) and 4-cation oxide Na2/3Ni1/3Mn1/3Fe1/3−xAlxO2 (NaNMFA) were prepared using the solid-state method, rather than the doping technology. In addition, the importance of the concept of entropy stabilization in material performance and battery cycling was demonstrated by testing 3-cation (NaNMF) and 4-cation (NaNMFA) oxides in the same system. Thus, NaNMFA can provide a reversible capacity of about 125.6 mAh·g−1 in the voltage range of 2–4.2 V, and has enhanced cycle stability. The capacity and decay law of the MEO batteries indicate that the configurational entropy (1.28 R (NaNMFA) > 1.10 R (NaNMF)) of the cationic system, is the main factor affecting the structural and cycle stability of the electrode material. This work emphasizes that the rational design of MEOs with novel structures and different electrochemically active elements may be the strategy for exploring high-performance SIB cathode materials in next-generation energy storage devices.

The distribution of natural fractures in coal seams and their effect on the anisotropy of the stress sensitivity of permeability are key issues that are commonly encountered in the simultaneous extraction of coal and gas. To fully understand the law of anisotropy of the effective porosity and stress sensitivity of coal permeability, a modified permeability model and the corresponding anisotropic evaluation index of the stress sensitivity were established considering the influence of the natural fracture distribution of coal. Based on anisotropic coal samples obtained from the Tashan coal mine, the effective porosity and permeability in three orthogonal directions under different stress conditions were systematically evaluated, and the anisotropic evolution law of the stress sensitivity of the permeability was quantitatively analyzed. The results show that the natural fracture system of coal exhibits complex heterogeneity, and the compressibility of the fractures in different directions is different, resulting in significant anisotropic permeability and stress sensitivity. The effective porosity sensitivity of the coal permeability exhibits a power relation with the effective porosity, and a higher effective porosity corresponds to a more notable anisotropy of the effective porosity sensitivity. Under a low stress, the coal stress sensitivity in the direction perpendicular to the bedding planes is the largest. When the stress increases to 19 MPa, the dominant direction of the stress sensitivity changes, and the direction parallel to the face cleats experiences the maximum stress sensitivity of permeability at a high stress level. The power index of the correlation between the coal permeability and effective porosity in different directions of the coal samples in the Tashan coal mine ranges from 2.42 to 9.18, and a constant value of 3 is not observed. This result can be attributed to the influence of the pore size, fracture width and difference in the pore–fracture distribution.

To improve the low compactness and limited size of powder metallurgy (P/M) aluminum alloy materials, cold rolling deformation on P/M aluminum alloy was carried out in this work. And the microstructure and mechanical properties of P/M aluminum alloy during cold rolling were investigated from multi-dimensional and multi-scale perspectives. The results indicate that the microstructure gradually evolved from the original equiaxial structure to the fiber structure after cold rolling. Also, the grain size decreased with an increase in cumulative reductions. When the cumulative reduction was increased from 0 to 80%, the relative density and tensile strength of the samples increased from 98.31% to 221.94 MPa to 99.04% and 302.88 MPa, respectively. On this basis, the synergetic effect of microstructure densification and deformation strengthening of the P/M 2024 Al alloy during cold rolling was investigated. The improved mechanical properties mainly resulted from the combined effects of the increased microstructural compactness and deformation strengthening.

A cost-effective totem-pole power factor correction converter with high-frequency gallium nitride high electron-mobility transistors and low-frequency Si diodes is investigated in this article. The reverse recovery characteristics of low-frequency diodes are evaluated experimentally. With the slow recovery characteristics, a negative current can flow through the low frequency diode, so that soft-switching and critical mode operation is achieved easily. However, if the duration of the negative current exceeds the reverse recovery time of the low-frequency diode, the diode will switch at high frequency, leading to severe losses and losing control of the inductor current. In order to avoid this issue, an adaptive off-time soft-switching strategy is adopted, and discontinuous conduction mode operation is suggested near the zero crossing of the grid voltage. Furthermore, since only the low-frequency grid current is sampled, this control strategy has the merits of low requirements on control resources and low cost. Experimental results of a 400W prototype are provided to verify the effectiveness of the proposed control strategy.

A new photosensitive dual-anisotropic conductive Janus film (PDCJF) is proposed for the first time. It is rationally designed and manufactured by facile electrospinning. PDCJF is firstly constructed using 2,7-dibromo-9-fluorenone (DBF) with photoconductive and luminescent properties. Janus nanofibers are respectively used as the building units to construct the top layer (T-PDCJF) and the bottom layer (B-PDCJF) of PDCJF. The two layers are tightly bonded to form PDCJF. Under light irradiation, there is photosensitive dual-anisotropic conduction in PDCJF, but there is no anisotropic conduction without light. Thus, the transition of PDCJF from mono-functional magnetism to tri-functionalities is realized under light and without light. The luminescence color of PDCJF is tunable and it emits white-light. This is made possible by modulating the amounts of luminescent substances and excitation wavelength. The microscopic Janus nanofibers used as building units and macroscopic Janus film structure ensure high photosensitive dual-anisotropic conduction and excellent fluorescence in PDCJF. The two-dimensional (2D) PDCJF is rolled to obtain three-dimensional (3D) Janus-type tubes and 2D plus 3D complete flag-like structures with exceptional multi-functionalities. The new findings can strongly guide in developing advanced multi-functional nanostructures.

The leaching of uranium in uranium soil will pose great risks to human health and the ecological environment. The immobilization of uranium by coal gangue geopolymers (CGG) and Nano-hydroxyapatite (nHAP)-based composite geopolymers were investigated in this study. The ability of geopolymers to immobilize uranium was evaluated in terms of the static and dynamic leaching concentration. The experimental results confirmed that the lowest static leaching concentration of composite uranium soil solidified body and uranium soil solidified body was 15.94 mg/kg and 21.27 mg/kg after 28 days of immobilization, respectively. During the 28-d dynamic leaching experiment, the highest leaching concentration was 155.38 mg/kg and 166.63 mg/kg, respectively. The composite uranium soil solidified body shows better overall leaching resistance.

Microrobots can expand our abilities to access remote, confined, and enclosed spaces. Their potential applications inside our body are obvious, e.g., to diagnose diseases, deliver medicine, and monitor treatment efficacy. However, critical requirements exist in relation to their operations in gastrointestinal environments, including resistance to strong gastric acid, responsivity to a narrow proton variation window, and locomotion in confined cavities with hierarchical terrains. Here, we report a proton-activatable microrobot to enable real-time, repeated, and site-selective pH sensing and monitoring in physiological relevant environments. This is achieved by stratifying a hydrogel disk to combine a range of functional nanomaterials, including proton-responsive molecular switches, upconversion nanoparticles, and near-infrared (NIR) emitters. By leveraging the 3D magnetic gradient fields and the anisotropic composition, the microrobot can be steered to locomote as a gyrating "Euler's disk", i.e., aslant relative to the surface and along its low-friction outer circumference, exhibiting a high motility of up to 60 body lengths/s. The enhanced magnetomotility can boost the pH-sensing kinetics by 2-fold. The fluorescence of the molecular switch can respond to pH variations with over 600-fold enhancement when the pH decreases from 8 to 1, and the integration of upconversion nanoparticles further allows both the efficient sensitization of NIR light through deep tissue and energy transfer to activate the pH probes. Moreover, the embedded down-shifting NIR emitters provide sufficient contrast for imaging of a single microrobot inside a live mouse. This work suggests great potential in developing multifunctional microrobots to perform generic site-selective tasks in vivo.

Determining the mechanical properties of frozen rock is highly important in cold-area engineering. These properties are essentially correlated with the content of liquid water remaining in frozen rock. Therefore, accurate determination of unfrozen water content could allow rapid evaluation of mechanical properties of frozen rock. This paper investigates the hysteresis characteristics of ultrasonic waves applied to sandstone (in terms of the parameters of P-wave velocity, amplitude, dominant frequency and quality factor Q) and their relationships with unfrozen water content during the freeze-thaw process. Their correlations are analysed in terms of their potential for use as indicators of freezing state and unfrozen water content. The results show that: (1) During a freeze-thaw cycle, the ultrasonic parameters and unfrozen water content of sandstone have significant hysteresis with changes in temperature. (2) There are three clear stages of change during freezing: supercooled stage (0 °C to −2 °C), rapid freezing stage (−2 °C to −3 °C), and stable freezing stage (−3 °C to −20 °C). The changes in unfrozen water content and ultrasonic parameters with freezing temperature are inverse. (3) During a single freeze-thaw cycle, the ultrasonic parameters of sandstone are significantly correlated with its unfrozen water content, and this correlation is affected by the pore structure. For sandstones with mesopores greater than 50%, there are inflection points in the curves of ultrasonic parameters vs. unfrozen water content at −3 °C during freezing and at −1 °C during thawing. It was found that thermal deformation of the mineral-grain skeleton and variations in the phase composition of pore water change the propagation path of ultrasonic waves. The inflection point in the curve of dominant frequency vs. temperature clearly marks the end of the rapid freezing stage of pore water, in which more than 70% of the pore water freezes. Consequently, the dominant frequency can be used as an index to conveniently estimate the unfrozen water content of frozen rock and, hence, its mechanical properties.

The deformation mechanism of the fine structure composed of primary α phase (αp) and acicular secondary α phase (αs) on quasi-static mechanical properties is still not very clear. The main controversy is focused on the role of αp in the mechanical behavior. In this paper, the microstructure of the heat-treated near β-type Ti-4.5Mo-5.1Al-1.8Zr-1.1Sn-2.5Cr-2.9Zn alloy after tensile tests was observed by transmission electron microscopy (TEM). And the results showed that in the slight deformation region the dislocations were accumulated at the intersection of αp and β matrix separated by αs, while only a few dislocations nucleated in β matrix. In the severe deformation region, a large quantity of dislocations in both αp and β matrix were observed. It can be inferred that αp deformed firstly and then activated the deformation of β matrix, that is, the thickness of αp and the inter-particle spacing of αs played a dominant role in the deformation process. The quantitative relationship between the yield strength and the microstructure parameters is consistent with this inference. By adjusting the solution treatment parameters and the subsequent aging treatment, three fine structures were obtained, and the corresponding mechanical properties were determined. Furthermore, the yield strength can be described by the mathematical model σy ​= ​756.4 ​+ ​135.6/hp1/2 +32.2/ds1/2, where hp and ds are the thickness of αp and the inter-particle spacing of αs, respectively.

Objective. To test the biomechanical properties of 3D printed tantalum and titanium porous scaffolds. Methods. Four types of tantalum and titanium scaffolds with four alternative pore diameters, #1 (1000-700 μm), #2 (700-1000 μm), #3 (500-800 μm), and #4 (800-500 μm), were molded by selective laser melting technique, and the scaffolds were tested by scanning electronic microscope, uniaxial-compression tests, and Young’s modulus tests; they were compared with same size pig femoral bone scaffolds. Results. Under uniaxial-compression tests, equivalent stress of tantalum scaffold was 411 ± 1.43 MPa, which was significantly larger than the titanium scaffolds ( P < 0.05 ). Young’s modulus of tantalum scaffold was 2.61 ± 0.02 GPa, which was only half of that of titanium scaffold. The stress-strain curves of tantalum scaffolds were more similar to pig bone scaffolds than titanium scaffolds. Conclusion. 3D printed tantalum scaffolds with varying pore diameters are more similar to actual bone scaffolds compared with titanium scaffolds in biomechanical properties.

Extensive studies have laid the groundwork for understanding peroxidase-like nanozymes. However, improvements are still required before their practical applications. On one hand, it is significant to explore highly reactive nanozymes. On the other hand, it is necessary to avoid fouling formed on the surface of nanozymes, which will affect their activity and the results of H2O2 sensors or H2O2-related applications. Herein, a strategy is reported to design osmium nanoclusters (Os NCs) with the existence of bovine serum albumin (BSA) through biomineralization. BSA-Os NCs were found to possess intrinsic peroxidase-like activity with a high specific activity (6120 U/g). Studies also found that the catalytic activity of BSA-Os NCs was better than those of reported protein-assisted metal nanozymes (e.g., BSA-Pt NPs and BSA-Au NCs). More significantly, BSA has been confirmed as a protective shell to give Os NCs extrinsic antifouling property in some typical ions (e.g., Hg2+, Ag+, Pb2+, I-, Cr6+, Cu2+, Ce3+, S2-, etc.), saline (0-2 M), or protein (0-100 mg/mL) conditions. Under optimal conditions, a colorimetric sensor was established to realize a linear range of H2O2 from 1.25 to 200 μM with a low detection limit of 300 nM. On this basis, remarkable features enable a BSA-Os NCs-based colorimetric sensor to detect H2O2 from complex systems with clear color gradients. Together, this work highlights the advantages of protein-assisted Os nanozymes and provides a paragon for peroxidase-like nanozymes in H2O2-related applications.

Background A novel luminescent sensor with dual-emitting platforms, Tb@UiO-66, was used for highly detecting Sm3+ and teflubenzuron. Methods Tb@UiO-66 was synthesized on basis of the exchange of guest molecules, where Tb3+ ions were encapsulated into the cages of UiO-66. Significant finds The results of multiband fluorescence originated from the linker-to-cluster charge transfer and the characteristic emission of TbIII. Tb@UiO-66 displayed luminescence enhancements or quenches according to small molecules. Especially for Sm3+ and teflubenzuron, the characteristic peaks of Tb@UiO-66 at 490, 545, 585, and 621 nm increased with the increasing of the concentration of the analytes, where Tb@UiO-66 exhibited the effect of luminescence enhancement. The detection limits for detecting Sm3+ and teflubenzuron were 0.09 μM and 0.21 μM, and the changes of luminescence intensities could be observed by naked eyes under the UV light at 365 nm. Tb@UiO-66 could also be used to detect teflubenzuron in real water samples. Tb@UiO-66 could be reused for at least 5 cycles for the detection of Sm3+ and teflubenzuron with the framework of Tb@UiO-66 uncollapsed. These results implied that the integration of LnIII luminescent materials and Zr-MOFs by doping method provided a new strategy for fabricating novel luminescent sensors for detecting polluting small molecules.

The type of inclusions in tundish steel and the formation mechanism of the submerged entry nozzle (SEN) clogging in the continuous casting of the rare earth (RE) high strength steel without calcium treatment were studied based on the plant trials and thermodynamic calculation. It was found that Ce2O3 and CeAlO3 in tundish molten steel were transformed into Ce2O2S + CaO–Al2O3 with the size of 2–3 μm during cooling. When the flow velocity of molten steel on surface of the SEN was slow due to the boundary layer effect, Ce2O3 inclusion in molten steel reacted with Al2O3 in the SEN refractory to form CeAlO3. With the continuous erosion of molten steel and reaction, the compositions of CeAlO3, Al2O3 and CaO were aggregated, and the clogging layers with different zones were formed on surface of the SEN. Meanwhile, a small amount of molten steel remaining in the arc zone and corner zone of the SEN formed solidified steel. When calcium treatment is canceled, the reaction probability between inclusions in molten steel and refractory should be reduced by improving the material and shape of the SEN.

The TiO2-Ag hybrid nanofluids were prepared by diluting high-concentration nanofluids and adding Span80 as surfactants. The stability of nanofluids was studied by taking photos of the nanofluids with storage time of 0–30 days. The thermal conductivity and dynamic viscosity were measured at different volume fraction, temperature and ultrasonication time. The results showed that compared with the base fluid, the maximum enhancement of thermal conductivity was 9.98%, and the maximum dynamic viscosity ratio was 2.78. And ultrasonication treatment is recommended to alleviate the sedimentation of nanofluids. Then, two artificial neural networks (ANNs) were established and the size of the networks was optimized according to the relative error to improve the ability to predict the thermal properties of nanofluids. The results show that the maximum relative error of the prediction of thermal conductivity and dynamic viscosity is 1.44% and 3.54%, respectively, which is beneficial to saving experiment time and cost.

Raw SrF2 powders were synthesized by the chemical precipitation method, and the mean particle size was 58.48 nm. Er:SrF2 transparent ceramics were obtained by hot-pressed (HP) technique, and the effect of ErF3 levels on the transparency, microstructure, luminescence spectroscopic and microhardness were studied. The ratio of emission intensities R (Red/Green) increased with the ErF3 doping levels. The addition of ErF3 was found effectively to reduce grain size and has a positive effect on improving the microhardness. The SrF2 ceramic doped with 5 wt.% ErF3 (2 mm thick) showed the best optical transparency, the transmittance at 500 nm and 1200 nm are 87.9 % and 89.5 %, respectively. The average grain size, Vickers hardness (Hv), and fracture toughness (KIC) for the SrF2 ceramic were 21.1 ± 4.5 μm, 1.73 ± 0.04 GPa, and 0.52 ± 0.08 MPa·m1/2, respectively.

To produce high strength and ductility Mg alloys with high productivity and low energy consumption, the residual heat rolling (RHR) process was initially proposed. The microstucture and mechanical properties of AZ31 processed by RHR were investigated by optical micrscopy (OM), electron backscatter diffraction (EBSD), and electron universal testing machine. The yield strength (YS), ultimate tensile strength (UTS), and elongation to failure of RHRed AZ31 sheet were 194 MPa 311 MPa, and 22%, respectively. The RHRed AZ31 alloys after annealing have very fine and homogeneous grains. The symmetrical rolled (SR) and RHRed AZ31 exhibit typical {0002} basal textures. The RHRed AZ31 has double-peak basal texture distribution. The basal poles of RHRed AZ31 split from normal direction (ND) to rolling direction (RD). There are few hard orientation distributions on the basal slip and more soft orientation distributions on the prismatic slip in the RHRed AZ31 sheets than those in the SRed AZ31sheets.

By placing a single Au nanoparticle on the surface of a cadmium sulfide (CdS) nanowire, we demonstrate strong coupling of localized surface plasmon resonance (LSPR) modes in the nanoparticle and whispering gallery modes (WGMs) in the nanowire. For a 50-nm-diameter Au-nanosphere particle, strong coupling occurs when the nanowire diameter is between 300 and 600 nm, with a mode splitting up to 80 meV. Using a temperature-induced spectral shift of the resonance wavelength, we also observe the anticrossing behavior in the strongly coupled system. In addition, since the Au nanosphere has spherical symmetry, the supported LSPR mode can be selectively coupled with transverse electric (TE) and transverse magnetic (TM) WGMs in the nanowire. The ultracompact strong-coupling system shown here may provide a versatile platform for studying hybrid “photon–plasmon” nanolasers, nonlinear optical devices, and nanosensors.

Friction between the tow and tool surface normally happens during the tow production, fabric weaving, and application process and has an important influence on the quality of the woven fabric. Based on this fact, this paper studied the influence of tension and relative velocity on the three kinds of untwisted-glass-fiber tow-on-roller friction with a Capstan-based test setup. Furthermore, an improved nonlinear friction model taking both tension and velocity into account was proposed. According to statistical test results, firstly, the friction coefficient was found to be positively correlated with tension and relative velocity. Secondly, tension and velocity were complementary on the tow-on-roller friction behavior, with neither being superior to the other. Thirdly, an improved model was found to present well the nonlinear characteristics between friction coefficient and tension and velocity, and predicational results of the model were found to agree well with the observations from Capstan tests.

Aims The aim of our study is to investigate the effect induced by alternated mechanical loading on Notch-1 in mandibular condylar cartilage (MCC) of growing rabbits. Methods A total of 64 ten-day-old rabbits were randomly divided into two groups according to dietary hardness: normal diet group (pellet) and soft diet group (powder). In each group, the rabbits were further divided into four subgroups by feeding time: two weeks, four weeks, six weeks, and eight weeks. Animals would be injected 5-bromo-2′-deoxyuridine (BrdU) every day for one week before sacrificing. Histomorphometric analysis of MCC thickness was performed through haematoxylin and eosin (HE) staining. Immunochemical analysis was done to test BrdU and Notch-1. The quantitative real-time polymerase chain reaction (qRT-PCR) and western blot were used to measure expression of Notch-1, Jagged-1, and Delta-like 1 (Dll-1). Results The thickness of MCC in the soft diet group was thinner than the one in normal diet group. Notch-1 was restricted in fibrous layer, proliferative layer, and hypertrophic layer. The expression of Notch-1 increased from two weeks to six weeks and then fell down. Notch-1 in normal diet group was higher than that in soft diet group in anterior part of MCC. The statistical differences of Notch-1 were shown at two, four, and six weeks (p < 0.05). The result of western blot and quantitative real-time PCR (qRT-PCR) showed the expression of Dll-1 and Jagged-1 rose from two to four weeks and started to decrease at four weeks. BrdU distributed in all layers of cartilage and subchondral bone. The number of BrdU-positive cells, which were less in soft diet group, was decreasing along with the experiment period. The significant difference was found at four, six, and eight weeks in anterior and posterior parts (p < 0.05). Conclusion The structure and proliferation of MCC in rabbits were sensitive to dietary loading changes. The proper mechanical loading was essential for transduction of Notch signalling pathway and development of mandibular condylar cartilage. Cite this article: Bone Joint Res 2021;10(7):437–444.

The flow behavior of binary-sized particles in a horizontal rotating cylinder drum (RCD) and rotating ellipsoidal drum (RED) based on the discrete element method (DEM) is predicted. The simulations in this work study the influence of flattening on the flow of binary-sized particles. The flow characteristics such as the mixing indices, the resulting contact forces, the translational granular temperature, the configurational temperature and the energy dissipation are predicted or calculated in the simulations. The results show that the changes in flattening and particle diameter can affect the flow significantly. At a high rotating speed, the mixing degree of binary-sized particles in the RED can be improved. The resulting contact forces gradually increase with the increasing of rotating speed and flattening. The large particle's velocity is larger than that of the small one. The change of rotating angle causes the oscillation of translational granular temperature and configuration temperature.

In this study, the LiFePO4 cathode was synthesized by the ionic thermal method using the deep eutectic mixture of tetramethyl ammonium chloride and urea. The synthetic conditions were systematically investigated by orthogonal experiments, which indicate that the optimal reaction time, reaction temperature, molar ratio of Li to DES and rotate speed are 96 h, 220 °C, 1:14 and 20 r·min −1, respectively. X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM) were characterized to investigate the crystalline structure and morphology of the obtained materials, indicating well-crystallized LiFePO4 with olivine structure. And the physical properties of LiFePO4 were explored through Fourier transform infrared spectroscopy (FTIR), 57Fe Mossbauer absorption spectra and Raman spectra. An initial discharge capacity can reach 151 mAh·g−1 at 0.1C rate for LiFePO4 following by calcining at 600 °C under the optimal conditions, and it retains 125.1 mAh·g−1 after 100 cycles. These results demonstrated that the addition of ionic liquids can improve the rate performance, cycle performance and ion diffusion rate of LiFePO4.

The carbonation process in alkali-activated slag cement concrete is more complicated. This paper reviews the research progress of carbonation resistance of alkali-activated slag cement concrete at home and abroad and summarizes the existing research on carbonation. The focus is on the carbonation mechanism, test methods, influencing factors and the effect of carbonation on the performance of alkali-activated slag cement concrete. The problems existing in the current research on the anti-carbonation property of alkali-activated slag cement concrete and the issues for further research are proposed.

The tensile strength of rock is a crucial parameter for the stability assessment and reinforcement design of rock engineering, which is commonly determined by indirect tension test or uniaxial direct tension test. However, the rock in slopes and underground caverns is often in a direct tension stress state under confining pressure, due to the stress redistribution induced by excavation or mining. In this study, the direct tension tests of granite samples under both different confining pressures and tensile loading rates were carried out by an auxiliary apparatus installed in pressure chamber, to investigate the confined tensile strength and fracture surface morphology. High-precision 3D laser scanning was used to obtain the morphology data and the geometrical statistics of asperities on fracture surface, containing the distributions of height, dip angle and dip direction of the asperities. The tensile strength first increases and then decreases with the increase in confining pressure, indicating that the maximum tensile strength of tested granite is not the uniaxial tensile strength and appears in the condition of a certain confining pressure. The tensile strength slightly increases with the increase in tensile loading rate. The fracture surface is smoother as confining pressure increases, while is rougher with the increase in tensile loading rate. As confining pressure goes up, from a micro-point of view, the friction force and the locking force between grains of granite have a similar changing rule to the tensile strength. The roughness of fracture is closely related with both micro-fracture pattern between grains and macro-fracture pattern concerning tensile and shear properties. These provide a reasonable explanation for the correlation of the tensile strength and fracture roughness with confining pressure and loading rate.

The effect of deep eutectic solvent (DES) modified silica on the properties of nature rubber (NR) composites were investigated. The DES is an environment-friendly and low-cost solvent, which was prepared by mixing choline chloride and urea in a 1:2 molar ratio. The NR composites filled with DES modified silica were prepared and the properties were tested. The interaction between the DES and silica were characterized by Fourier transform infrared spectroscopy (FTIR), the interaction between silica and silica were tested by differential scanning calorimetry (DSC). The dynamic properties, such as rolling resistance and wet skid resistance, and were tested by dynamic mechanical analysis (DMA). Morphologies of the composites were characterized by scanning electron microscopy (SEM). The results indicate that the DES can interact with silica by hydrogen bond to improve the compatibility between the rubber and silica. When the content of DES was 3 phr, the tensile strength, modulus at 300%, tear strength, and the crosslinking density of the composites was increased. At the same time, the proper content of DES can reduce the rolling resistance of the vulcanized rubber while maintaining good wet skid resistance.

To study the effects of anisotropy and heterogeneity on the shale failure mode and tensile strength, Brazilian splitting tests were performed from both directions of the bedding and layer thickness. Layers containing different bedding and loading angles and layer thicknesses were obtained separately. The results show that, at 0° and 90° angles, the shale cracks grow “linearly”; at 15°, the shale cracks have “arc type” growth; and at 30°–75°, the shale-splitting displays “broken line” crack propagation. The tensile strength from 0° to 90° exhibits an increasing trend. Water has a significant softening effect on the tensile strength of shale—the higher the water content, the lower the tensile strength. In addition, a 3DEC numerical simulation was used to simulate the tests, establishing shale specimen particles with random blocks. In the shale disc, uneven parallel bedding and uniform parallel bedding were set up with different loading angles and layer thicknesses to generate simulated stress-displacement curves, and the effect of layering on shale cleavage was analyzed from a mesoscopic perspective. The tensile strength of shale with uniform parallel bedding was found to be higher under the same conditions, which is consistent with the experimental results. By comparing the experimental and simulation results, from both the macro- and mesoperspectives, the Brazilian splitting crack growth of shale is affected by bedding, displaying a process from disorder to order. This study is of great significance for further exploration of the mechanical properties of shale under loading failure.

Fatigue damage accumulation is a critical factor resulting in the failure of prestressed concrete (PC) bridges. The fatigue damage is usually caused by the coupled effect of cyclic vehicle loading and environmental corrosion. This study investigated probabilistic fatigue damage on aging PC bridges considering both stochastic traffic loading and corrosion. A stochastic traffic model was derived based on long-term monitoring data aiming to simulate fatigue stress spectra of critical rebar. The effect of cracks on the fatigue stress spectra was investigated in order to model the fatigue stress state more realistically. A three-stage traffic growth model was established based on traffic volume histories of three highways in China. A fatigue limit state function considering traffic growth and corrosion effect was deduced for fatigue reliability assessment of PC bridges. Numerical results show that the stress amplitude of rebar considering cracks is 1.53 times greater than the rebar with no-cracks, resulting in a decrease of fatigue life by 68 years. In addition, the three-stage traffic growth models lead to 25 years shorter fatigue life than the one considering a linear traffic growth model. Finally, the corrosion effect results in a fatigue life of 44 years. The numerical results provide a theoretical basis for fatigue life estimation and maintenance of aging PC bridges.

A unique method is developed to synthesize Sn nanomaterials. Through an oxidation–reduction treatment, Sn particles are refined from the submicron (300 nm) to nanoscale (88 nm). With a series of ex...

It is challenging to accurately establish the dynamic heat transfer model of the internal thermal mass owing to the irregular shape. In building energy simulation software, the internal thermal mas...

To develop a safer immunosuppressant for organ transplantation and autoimmune disease treatment, in this study, several of novel amino alcohol derivatives containing thioether moiety were synthesized with 7-bromo-tetralin-2-one as starting material, and Suzuki coupling reaction and Bucherer-Bergs reaction as key steps. Their activity as sphingosine 1-phosphate receptor type 1 (S1P1) agonists were evaluated by [γ-35S] GTP binding assay. Among the thioether substituted compounds, compound10showed good activity as S1P1agonist at low micromolar concentration (EC50 = 0.698 μmol/L). The result suggested that it has potential activity against autoimmune diseases and immunosuppressant of organ transplantations.

In recent years, the oil field chemical A-cyanoacrylate mixed adhesive has been used in rock preparation and preparation to a certain extent, and its role has been paid more and more attention due to the solidification of the rock surface in the rock thin section, the early embedding of the rock, and the adhesion of the thin side of the rock to the slide surface, etc. This paper introduces the preparation and application development of a-cyanoacrylate mixed adhesive in geological experiment, and the development of a-cyanoacrylate mixed adhesive in oilfield geological experiment.

Ni-rich cathodes exhibit appealing properties, such as high capacity density, low cost, and prominent energy density. However, the inferior ionic conductivity and bulk structural degradation become bottlenecks for Ni-rich cathodes and severely limit their commercial utilization. Traditional coating and doping methods suffer fatal drawbacks in functioning as a unit and cannot radically promote material performance to meet the needs of Li-ion batteries (LIBs). Herein, we successfully devised an ingenious and facile synthetic method to establish Ni-rich oxides with a La2Zr2O7 coating and Zr doping. The coating layer improves the ion diffusion kinetics and enhances Li-ion transportation while Zr doping effectively suppresses the phase transition of LiNi0.8Co0.1Mn0.1O2 cathode. Owing to the synergetic effect of Zr doping and La2Zr2O7 coating, the modified material shows prominent initial discharge capacity of 184.7 mAh g−1 at 5 °C and maintains 177.5 mAh g−1 after 100 cycles at 1 °C. Overall, the proposed feasible electrode design method can have a far-reaching impact on further fabrication of advanced cathodes for high-performance LIBs.

Herein, CuO/Cu2O heterostructured arrays were successfully realized by in situ sculpturing Cu foam based on the hydrothermal protocol. Owing to the state-of-the-art design, CuO/Cu2O nanosheet arrays are tightly and intimately grown on Cu substrate. The abundant holes formed by the unique three-dimensional construction of Cu foam and the porous CuO/Cu2O nanosheets are significantly beneficial to the infiltration of electrolyte and enhancement of the Na+ diffusion efficiency. It is noted that CuO/Cu2O electrode shows superior areal capacity than that of the individual CuO and Cu2O electrodes. At the current density of 0.6 mA cm−2, there is a reversible capacity of 1.0 mAh cm−2 (322.6 mAh g−1) for the CuO/Cu2O anode. Even at 2.0 mA cm−2, a reversible capacity of 0.56 mAh cm−2 (180.6 mAh g−1) can be still obtained. The full sodium-ion battery demonstrates a high reversible capacity of 0.53 mAh cm−2 (170.9 mAh g−1) in the initial cycle at 0.5 mA cm−2.

Profile requirements of silicon steel strip are extremely high and the thickness difference of cold-rolled products is usually less than 7 μm, and the profile quality of hot-rolled strip is the key to ensure the thickness difference of cold-rolled products. In order to produce the silicon steel strip with high-precision shape, the concept of quasi-rectangular rolling during hot continuous rolling was put forward; the equipment configuration and technical method of approximate rectangular section control were studied. Through the roughing multi-target load distribution technology and the roll configuration technology for uniform wear of a 4-high rolling mill, the strip crown of transfer bar was reduced and the profile control stability was guaranteed. Configuring variable contact back-up roll technology on all stands in the finishing rolling process, equipped with symmetry variable taper work roll and long-stroke intelligent shifting strategy in the downstream stands, and using side rolling lubrication technology can make the roll wear more uniform, reduce the edge drop of silicon steel strip, improve the profile quality, and make the strip section of finishing exit "quasi-rectangular". In addition, induction furnace and side heater were also equipped to guarantee the temperature uniformity of the strip, so as to improve the stability of profile control. The whole control technology is based on the 1580-mm hot continuous rolling production line, designed, and developed according to the characteristics of equipment and products, and has been successfully applied, which can obtain the approximate rectangular strip section satisfying the flatness quality, and improve the strip section precision of silicon steel and other products.

Transistors are typically based on inorganic or organic semiconductors. Metals have generally been considered unsuitable for such use because bulk metals screen electric fields and thus achieving electrically tunable conductivity is difficult. Alternatively, gradients of counterions in films of metal nanoparticles functionalized with charged organic ligands can be used to construct electronic devices, including resistors, diodes and sensors, but modulating the conductivity in these systems has also proven to be challenging. Here we show that transistors and logic circuits can be created from thin films of functionalized gold nanoparticles using dynamic ionic gradients established via an unconventional five-electrode configuration. The transistors are capable of a 400-fold modulation of electrical conductivity, and by combining with metal nanoparticle diodes and resistors, can be used to construct NOT, NAND and NOR logic gates, as well as a half-adder circuit. We also show that transistors deposited on flexible substrates continue to work when deformed and can withstand electrostatic discharges. Dynamic ionic gradients of counterions in films of metal nanoparticles functionalized with charged organic ligands can be used to create transistors that are capable of a 400-fold modulation of the electrical conductivity and can be used to construct logic gates and half-adder circuits.