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Shrink-fitted ceramic sleeve rollers are recently developed to be used efficiently in steel manufacturing industries. However, at times, the shaft moves out of the ceramic sleeve during cyclic loading because only small a shrink-fitting ratio can be applied. Given that the driving-out forces Fd can be calculated as the contact force occuring at the stoppers, this study considers the simplified two-dimensional model with stoppers. Then, the effects of several design factors on the driving-out force are discussed by varying the friction coefficient, shrink-fitting ratio δ/d, shrink-fitted length, and Young’s modulus of the inner shaft. Results show that the driving-out force takes a maximum value of approximately δ/d = 0.3×10−3 and then sharply decreases to Fd = 0 at approximately δ/d = 0.45×10−3. The shaft moving out can be prevented by designing a suitable stopper with sufficient strength for maximum value.

First principle calculations were performed to investigate the structural, mechanical, electronic properties, and thermodynamic properties of three binary Mg–B compounds under pressure, by using the first principle method. The results implied that the structural parameters and the mechanical properties of the Mg–B compounds without pressure are well matched with the obtainable theoretically simulated values and experimental data. The obtained pressure–volume and energy–volume revealed that the three Mg–B compounds were mechanically stable, and the volume variation decreases with an increase in the boron content. The shear and volume deformation resistance indicated that the elastic constant Cij and bulk modulus B increased when the pressure increased up to 40 GPa, and that MgB7 had the strongest capacity to resist shear and volume deformation at zero pressure, which indicated the highest hardness. Meanwhile, MgB4 exhibited a ductility transformation behaviour at 30 GPa, and MgB2 and MgB7 displayed a brittle nature under all the considered pressure conditions. The anisotropy of the three Mg–B compounds under pressure were arranged as follows: MgB4 > MgB2 > MgB7. Moreover, the total density of states varied slightly and decreased with an increase in the pressure. The Debye temperature ΘD of the Mg–B compounds gradually increased with an increase in the pressure and the boron content. The temperature and pressure dependence of the heat capacity and the thermal expansion coefficient α were both obtained on the basis of Debye model under increased pressure from 0 to 40 GPa and increased temperatures. This paper brings a convenient understanding of the magnesium–boron alloys.

Conformationally rigid X-shaped PAHs are attracting interest due to their self-assembly into unique networks and as models to study through-space exciton and charge delocalization in one single molecule. We report here the synthesis of X-shaped PAHs by dimerization of diazaheptacene diimides. The diimide groups are employed to effectively direct the self-assembly into antiparallel dimer aggregates, which assist the compounds to undergo a regiocontrolled [4 + 4] dimerization, leading to an X-shaped conformation bearing electron-poor and -rich subunits. The resulting PAHs are found to pack in 2D layers with large open channels and infinite π⋯π arrays. Furthermore, these highly crystalline porous materials serve as electron-transporting materials in OFETs due to the long-range π-stacked arrays in the layers. This work presents a potentially generalizable strategy, which may provide a unique class of porous semiconductors for organic devices, taking advantage of their open channels., The synthesis of conformationally rigid X-shaped PAHs by regiocontrolled cyclodimerization of diazaheptacene diimides is presented. The resulting porous materials exhibit enhanced semiconducting behaviors with large open channels.

The strength of light-matter interaction is of central importance in photonics and optoelectronics. For many widely studied two-dimensional semiconductors, such as MoS2, the optical absorption due to exciton resonances increases with thickness. However, here we will show, few-layer black phosphorus exhibits an opposite trend. We determine the optical conductivity of few-layer black phosphorus with thickness down to bilayer by infrared spectroscopy. On the contrary to our expectations, the frequency-integrated exciton absorption is found to be enhanced in thinner samples. Moreover, the continuum absorption near the band edge is almost a constant, independent of the thickness. We will show such scenario is related to the quanta of the universal optical conductivity of graphene (σ0 = e2/4ħ), with a prefactor originating from the band anisotropy., For many two-dimensional semiconductors, such as MoS2, the exciton absorption increases with thickness. Here, the authors show that, in black phosphorus, less material absorbs more light due to exciton resonances.

Aramid fibre-reinforced epoxy composites (AF/EP) are promising materials in the aerospace, transportation, and civil fields owing to their high strength, high modulus, and light weight. Thick composite laminates are gradually being applied to large composite structures such as wind turbine blades. During curing, temperature overheating is a common problem in thick composites, which leads to matrix degradation, thermal residual stresses, and uneven curing. This paper proposes a signal-to-noise ratio (SNR) method to optimise the curing cycle of thick AF/EP laminates and reduce the overheating temperature. During curing, the temperature and strain evolution in a thick AF/EP laminate were monitored using fibre Bragg grating sensors. The effects of the curing factors on the overheating temperature of the thick AF/EP laminate were evaluated using the Taguchi method and predicted via the SNR method and analysis of variance. The results indicate that the dwelling temperature is the main factor affecting the overheating temperature. The optimal curing cycle involves an overheating temperature of 192.72 °C, which constitutes an error of 2.58% compared to the SNR method predictions. Additionally, in comparison to the initial curing cycle, the overshoot temperature in the optimised curing cycle was reduced by 58.48 °C, representing a reduction ratio of 23.28%.

The effects of Al−Ti−C and La on the fluidity of a ZL205A alloy after separate and combined addition were studied by conducting a fluidity test. The fluidity of the ZL205A alloy first increased and then decreased with the increasing addition of Al−Ti−C and La, it peaked at 0.3% and 0.1% for Al−Ti−C and La, respectively. The combined addition of Al−Ti−C and La led to better fluidity, which increased by 74% compared with the base alloy. The affecting mechanism was clarified through microstructure characterization and a DSC test. The heterogeneous nucleation aided by Al−Ti−C and La, the number of particles in the melt, and the evolution of the solidification range all played a role. Based on the evolution of the fluidity and grain size, the optimal levels of Al−Ti−C and La leading to both high fluidity and small grain size were identified.

Massive composite components manufactured by autoclave curing in large framed molds are extensively used in the aerospace industry. The high temperature performance of the large framed mold is the key to achieving the desired composite part quality. This paper explores and summarizes the important thermal properties of metal and heat transfer fluid materials influencing the heating performance of large framed molds, with the aim of improving the mold temperature distribution. Considering the fluid–thermal–solid interaction inside the autoclave, a reliable computational fluid dynamics (CFD) simulation model was developed and verified by a temperature monitoring experiment to achieve the prediction of the temperature distribution of the large framed mold. Then, numerical simulations were designed on the basis of the CFD model, and the single-variable method was used to study the effects of the material thermal properties on the temperature performance of large framed molds. Our simulation predicts that when copper is used as the mold material, the temperature difference decreases by 30.63% relative to that for steel, and the heating rate increases by 3.45%. Further, when helium is used as the heat transfer medium, the temperature difference decreases by 68.27% relative to that for air, and the heating rate increases by 32.76%. This paper provides a reference for improvement of large framed mold manufacturing and autoclave process in terms of heating rate and temperature uniformity.

A four-step synthesis of Remdesivir (1) is presented. This work focuses on the yield improvement of step 1, flow chemistry development of step 2 and 3, process optimization of step 4. The literatures reported (https://dx.doi.org/10.1021/acs.oprd.0c00310 and https://dx.doi.org/10.1021/acs.oprd.0c00172: SI part) step 1 was repeated, but failed in the crystallization, eventually step 1 product was obtained by column chromatography with >98% HPLC purity and 40% IY. The flow chemistry development of step 2(IY: 84%) and 3 (IY: 63%) was achieved and the release of toxic HCN was avoided, the process robustness was improved by flow chemistry. Step 4 was simplified to apply primary alcohol 6 directly (without protection) to react with chiral SM 8. Lewis acid catalysts were screened by HTS and MgI2 gave 50% AY. Cheap and commercially available MgCl2 and NaI were used to replace MgI2, finally Remdesivir (1) was obtained in >99% purity with 40.3% IY.

The bimetallic work rolls are widely used in the roughing stands of hot rolling stand mills. The rolls are classified into two types; one is a single-solid type, and the other is a shrink-fitted assembled type consisting of a sleeve and a shaft. Regarding the assembled rolls, the interfacial creep sometimes appears between the shaft and the shrink-fitted sleeve. This interfacial creep means the relative displacement on the interface between the sleeve and the shaft. This creep phenomenon often causes damage to the roll such as shaft breakage due to fretting cracks. Although to clarify this creep mechanism is an important issue, experimental simulation is very difficult to be conducted. Since few studies are available, in this paper, the interfacial creep phenomenon is simulated by using the elastic finite element method (FEM) analysis. Here, the roll rotation is replaced by the road shift on the fixed roll surface. It is found that the interface creep can be explained as the accumulation of the relative circumferential displacement along the interface.

To study the effects of spacing on the downward flame spread over polymethyl methacrylate (PMMA), an experiment was conducted by pure PMMA (with 200 mm height, 50 mm width, and 1 mm thickness) with spacings of 7 mm, 10 mm, 13 mm, 16 mm, 19 mm, 22 mm, and 25 mm to observe the flame height, pyrolysis spread rate of fuels, and heat feedback from the wall. The heat feedback received by PMMA was used to analyze the influencing mechanism of wall spacing on flame spread. The results are as follows: (1) The average flame height decreases with the increase in distances ( $$\delta$$ ). This decrease in average flame height cycles through two stages: a fast drop stage and a slow drop stage. (2) The average pyrolysis spread rate first increases with the increase in distance, and a maximum pyrolysis spread rate occurred in the 13 mm spacing scenario. Then, the average pyrolysis spread rate decreases monotonously when the distance between wall and sample exceeds 13 mm. (3) The heat flux received by the sample consists of both heat flux from the flame and heat feedback from the wall. With the increase in distance, the heat feedback from the wall follows a downward trend, while the heat flux from the flame first increases and then remains constant. Because of the effects of heat flux from flame and heat feedback from the wall, the heat flux received by the sample first increases and then decreases with the increase in distance.

Ceramic roller can be used in the heating furnace conveniently because of its high temperature resistance. The roller consists of ceramic sleeve and steel shaft connected only under a small shrink fitting ratio because of the brittleness. However, the coming out of the shaft sometimes happens from the ceramic sleeve under repeated loading. Therefore, it is important to find out the driving out force to prevent the coming out failure. Based on the previous studies, a two-dimensional shrink fitted structure is considered by replacing the shaft with the inner plate and by replacing the sleeve with the outer plate. Then, the driving out force is focused in this study by introducing a newly designed stopper on the outer plate. The finite element simulation shows that the coming out phenomenon can be prevented due to the stopper installed on the outer plate. Then the mechanism of driving out force generation is clarified. Finally, the process of coming out is explained in terms of the residual displacement.

Rigid three-dimensional (3D) polycyclic aromatic hydrocarbons (PAHs), in particular 3D nanographenes, have garnered interest due to their potential use in semiconductor applications and as models to study through-bond and through-space electronic interactions. Herein we report the development of a novel 3D-symmetric rylene imide building block, triperyleno[3,3,3]propellane triimides (6), that possesses three perylene monoimide subunits fused on a propellane. This building block shows several promising characteristics, including high solubility, large π-surfaces, electron-accepting capabilities, and a variety of reactive sites. Further, the building block is compatible with different reactions to readily yield quasi-D3h symmetric nanostructures (9, 11, and 13) of varied chemistries. For the 3D nanostructures we observed red-shift absorption maxima and amplification of the absorption coefficients when compared to the individual subunits, indicating intramolecular electronic coupling among the subunits. In addition, the microplates of 9 exhibit comparable mobilities in different directions in the range of 10−3 cm2 V−1 s−1, despite the rather limited intermolecular overlap of the π-conjugated moieties. These findings demonstrate that these quasi-D3h symmetric rylene imides have potential as 3D nanostructures for a range of materials applications, including in organic electronic devices.

The structural properties, elastic anisotropy, electronic structures and work function of D022-type Al3TM (TM = Sc, Ti, V, Y, Zr, Nb, La, Hf, Ta) are studied using the first-principles calculations. The results indicate that the obtained formation enthalpy and cohesive energy of these compounds are in accordance with the other calculated values. It is found that the Al3Zr is the most thermodynamic stable compound. The mechanical property indexes, such as elastic constants, bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio, and Vickers hardness are systematically explored. Moreover, the calculated universal anisotropic index, percent anisotropy and shear anisotropic factors of D022-type Al3TM are analyzed carefully. It demonstrates that the shear modulus anisotropy of Al3La is the strongest, while that of Al3Ta is the weakest. In particular, the density of states at Fermi level is not zero, suggesting that these phases have metal properties and electrical conductivity. More importantly, the mechanisms of correlation between hardness and Young’s modulus are further explained by the work function. Finally, the experimental design proves that D022-Al3Ta has an excellent strengthening effect.

Al-Ti-C master alloys with different Ti/C mass ratios were fabricated by self-propagating high-temperature synthesis (SHS).Besides, the effect of Ti/C mass ratio on the microstructure of SHS products and its effect on the grain refinement of industrial pure aluminum were also investigated. The results indicated that the product with Ti/C mass ratio of 4:1 is mainly composed of TiC particles with average size of 0.81 μm, and there is only a small amount of rod-shaped Al3Ti in the sample. When the Ti/C mass ratio is increased to more than 10:1, the rod-shaped Al3Ti is the main product in master alloy, which has the most obvious effect on the refinement of pure aluminum. When the addition amount is 3 wt%, the average grain size decreased to about 191 μm. The Al-Ti-C master alloy with Ti/C mass ratio of 4:1 has better anti refining degradation performance. When add 1.2% of the above master alloy to pure aluminum, holding time 60 min, the macroscopic grains of industrial pure aluminum is more uniform and finer, with an average grain size of 324 µm. The results indicate that the morphology of TiC particles in the product changes from regular sphere to polyhedron with the increases of mass ratio of Ti/C, the average size of TiC particles increases, and the rod-shaped Al3Ti changes from thick rod to thin rod, the average size of rod-shaped Al3Ti decreases.

The first-principles calculations have been performed to predict the effect of transition-elements substitution on mechanical properties and electronic structures of B2-AlCu compounds. The results show that Zn, Cd, La and Hg are preferred to replace Al atom, while other transition elements are preferred to replace Cu atom. Among the mechanically stable AlCu-TM compounds, the resistance of axial deformation is greater than that of shear deformation. According to Poisson's ratio and Pugh criteria, all compounds show ductility. The compounds of Al8Cu7Fe, Al8Cu7Tc and Al8Cu7Re exhibit excellent Young's modulus and Vickers hardness in fourth, fifth and sixth periods, respectively. The bulk moduli of all AlCu-TM compounds indicate a low degree of isotropic deviation, while the shear moduli have a large anisotropy. The analysis of the electronic structures of Al8Cu7Fe, Al8Cu7Tc and Al8Cu7Re demonstrates that metal bond and covalent bond are mixed, and the properties of covalent bond between TM and Cu are weak.

The observation of electrically tunable and highly confined plasmons in graphene has stimulated the exploration of interesting properties of plasmons in other two-dimensional materials. Recently, hyperbolic plasmon resonance modes have been observed in exfoliated ${\mathrm{W}\mathrm{Te}}_{2}$ films, a type-II Weyl semimetal with layered structure, providing a platform for the assembly of plasmons with hyperbolicity and exotic topological properties. However, the plasmon modes were observed in relatively thick and small-area films, which restrict the tunability and application for plasmons. Here, large-area (approximately cm) ${\mathrm{W}\mathrm{Te}}_{2}$ films with different thicknesses are grown by the chemical vapor deposition method, in which plasmon resonance modes are observed in films with different thicknesses down to about 8 nm. Hybridization of plasmon and surface polar phonons of the substrate is revealed by mapping the plasmon dispersion. The plasmon frequency is demonstrated to be tunable by changing the temperature and film thickness. Our results facilitate the development of a tunable and scalable ${\mathrm{W}\mathrm{Te}}_{2}$ plasmonic system for revealing topological properties and towards various applications in sensing, imaging, and light modulation.

Gate dielectric/substrate interface is crucial to the electrical performance of nano-devices. However, the investigation on characterization of interfacial atomic and electronic structures is still lacking. In this paper, first principles modeling and calculation were performed to investigate the atomic and electronic properties of the HfO2/Si interface. The optimized bulk models of Si and tetragonal HfO2 were combined to build the HfO2/Si interface with the assistance of Quantum Espresso software. Band structure and density of states were calculated based on the density functional theory (DFT). It was found that the weakly bounded oxygen moves towards the interfacial region obviously after relaxation which due to the strong interaction between interfacial Si and oxygen atoms. Chemical bonds at the HfO2/Si interface are easier to be broken than that of bulk atoms because interfacial bond length increases significantly. The additional interfacial states were generated after the construction of the interface. Our results reveal the mechanism of the changes between bulk models and the HfO2/Si interface from an atomic perspective, which is expected to be benefited to the performance optimization of electronic devices.

Through infrared spectroscopy, we systematically study the pressure effect on electronic structures of few-layer black phosphorus (BP) with layer number ranging from 2 to 13. We reveal that the pressure-induced shift of optical transitions exhibits strong layer-dependence. In sharp contrast to the bulk counterpart which undergoes a semiconductor to semimetal transition under ~1.8 GPa, the bandgap of 2 L increases with increasing pressure until beyond 2 GPa. Meanwhile, for a sample with a given layer number, the pressure-induced shift also differs for transitions with different indices. Through the tight-binding model in conjunction with a Morse potential for the interlayer coupling, this layer- and transition-index-dependent pressure effect can be fully accounted. Our study paves a way for versatile van der Waals engineering of two-dimensional BP., Comment: 16 pages, 4 figures

Carbon steel and Cu-Pb-Sn bimetallic samples were prepared by the solid–liquid composite method. The preheating temperature of the steel matrix was 1150 ± 30 °C and the Cu-Pb-Sn alloy smelting temperature was 1200 ± 20 °C. The Cu-Pb-Sn alloy was subsequently poured into the preheated steel matrix to form a bimetallic composite interface. The influence of phosphorus (P) on the microstructure and mechanical properties of the interface and the behavior mechanism of P at the bimetallic interface were examined. The results showed that when the P content was 0.1% (all contents reported herein are in wt.%), the carbon steel and Cu-Pb-Sn alloy formed an ideal metallurgical bonding interface. It was found that a nanoscale Fe3P phase was precipitated at 750 °C at the grain boundary of the ɑ-Cu interface. The Fe3P interplanar spacing of the phase was 2.1 A, and the interplanar spacing of ɑ-Cu was 2.07 A. When the P content reached 0.2%, the Fe3P phase precipitated at 1020 °C and aggregated into micrometer size at the interface, which formed a transition zone with ɑ-Cu. The transition zone widened with an increase in the P content in the alloy liquid. The interface atomic diffusion distance between Fe and Cu was 11.55 μm when the P content was 0.1%, and the sample shear strength reached a maximum value of 157.89 MPa. With increasing P content, the interface became hard and brittle because it emerged in the precipitated transition zone, which decreased the shear strength.

The development of high-voltage and high-power cables requires polymeric dielectric materials with excellent insulation properties. Nanodoping is an effective method to promote electrical strength of polymers. This work focuses on the comparison of different breakdown models and reveals the mechanism of electrical breakdown of low-density polyethylene/alumina (LDPE/Al 2 O 3 ) nanocomposites, by comparing the simulation results calculated by different models with experimental results. We utilized space charge modulated electrical breakdown with a maximum electric field criterion (SCEBEF), space charge modulated electrical breakdown with a maximum energy gain criterion (SCEBEG), charge transport and molecular displacement modulated electrical breakdown (CTMD) models to investigate how the interaction between nanofillers and polymer enhances the electrical strength of LDPE/Al 2 O 3 nanocomposites. It is found that electrical breakdown fields calculated by CTMD model coincide with experimental results for nanofiller contents ranging from Owt% to 5wt%, and the coincidence is much better than those obtained by SCEBEF and SCEBEG models. The electrical breakdown field of LDPE/Al 2 O 3 nanocomposites is increased by 25.7% compared with the neat LDPE sample, and the breakdown strength can be enhanced at relatively low loadings while it will decrease at relatively high loadings.

In this study, the cohesive energy, interfacial energy, electronic structure, and bonding of Mg2Si (111)/Mg3Sb2 (0001) were investigated by using the first-principles method based on density functional theory. Meanwhile, the mechanism of the Mg3Sb2 heterogeneous nucleation potency on Mg2Si grains was revealed. The results indicated that the Mg3Sb2 (0001) slab and the Mg2Si (111) slab achieved bulk-like characteristics when the atomic layers N &ge, 11, and the work of adhesion of the hollow-site (HCP) stacking structure (the interfacial Sb atom located on top of the Si atom in the second layer of Mg2Si) was larger than that of the other stacking structures. For the four HCP stacking structures, the Sb-terminated Mg3Sb2/Si-terminated Mg2Si interface with a hollow site showed the largest work of adhesion and the smallest interfacial energy, which implied the strongest stability among 12 different interface models. In addition, the difference in the charge density and the partial density of states indicated that the electronic structure of the Si-HCP-Sb interface presented a strong covalent, and the bonding of the Si-HCP-Mg interface and the Mg-HCP-Sb interface was a mixture of a covalent bond and a metallic bond, while the Mg-HCP-Mg interfacial bonding corresponded to metallicity. As a result, the Mg2Si was conducive to form a nucleus on the Sb-terminated-hollow-site Mg3Sb2 (0001) surface, and the Mg3Sb2 particles promoted the Mg2Si heterogeneous nucleation, which was consistent with the experimental expectations.

Soil-water characteristic curve (SWCC) is a key constitutive relationship for studying unsaturated soil, and as is known, microstructure of the soil has great influence on the mechanical behaviour of the soil. In this study, the wetting and drying soil-water characteristic curves (SWCCs) of loess compacted at three different water contents were measured using the filter paper method. And microproperties of compacted loess were obtained by the mercury intrusion method (MIP) and scanning electron microscope (SEM). Results show that the compaction water contents have significant influence on the SWCC and microstructure. The pore size distribution (PSD) curves have great differences in macropore range and are similar in micropore range. Loess compacted at optimum and dry of optimum are generally connected, while there are certain number of nonintruded pores in loess compacted at wet of optimum. The SWCC curves vary significantly in low suction (ua − uw ua − uw ≥ 1000 kPa). Hysteresis in the SWCCs is more obvious for loess compacted at optimum and dry of optimum in the matric suction of 0∼100 kPa; however, there is a pronounced hysteresis for loess compacted at wet of optimum in full matric suction range. The characteristic of the SWCCs including their hysteresis can be well interpreted from the loess microstructure.

For tertiary oil recovery, the gas drive is often implemented after water flooding. The three-phase flow phenomenon of oil, gas, and water exists during the process of gas injection. The three-phase relative permeability should be measured to further study the flow characteristics of oil, gas, and water in porous media. In this work, the steady-state flow method is adopted to establish a combined experimental method based on the principle of relationship between resistivity and water saturation, and the principle of on-line CT scanning is used to measure the three-phase relative permeability. The relative permeability of oil, gas, and water is measured under different saturation histories, including the water alternating gas flooding, in which water saturation decreases, oil saturation decreases, and gas saturation increases, as well as gas alternating water flooding, in which water saturation increases, oil saturation decreases, and gas saturation decreases. The experimental results show that in a water-wet core, the relative permeability of water is a function of its own saturation, and its isoperms are straight lines. The relative permeability of oil and gas phase is affected by their saturation and other phase saturations. In an oil-wet core, the isoperms of oil, water, and gas are convex to the point of 100% their own saturation, which means the relative permeability of oil, gas and water depend on all the three phase saturations. The saturation histories influence the isoperms of the three phases differently. Compared with the two-phase flow, the three-phase flow is more complex. This new experiment provides an approach and theory for the study of three-phase seepage laws in the gas drive.

A new wire-grid transverse electromagnetic (TEM) horn as an electromagnetic pulse (EMP) radiating-wave simulator, with resistors, two PEC vertical plates and two sloping PEC plates loaded, are given. And the radiation fields of the new horn are simulated by parallel finite-difference time-domain (FDTD) method. The EMP’s effects of the new horn are numerically studied and analyzed. The results show that the full width at half maximum (FWHM) of electric field increases as the total resistance of each wire increases and the tail effect of waveform weaken efficiently. The low-frequency characteristic of the new horn is improved greatly comparing with the normal TEM horn antenna.

An innovative frame system called rocking buckling-restrained brace frame (RBRBF), which is characterized by allowing the column base uplifting during strong earthquakes, has been proposed to decrease seismic damage and reduce repair cost of building structures after the disaster. According to the working mechanism and functional objectives of this new type of structure system, four buckling-restrained brace steel frames including two rocking ones were designed as half-scale specimens considering various parameters. Pseudo-static tests were conducted on the model specimens to investigate their seismic performance, the yielding mechanism and the damage mode. The experimental results illustrated that the lateral resisting capacity and initial stiffness between the rocking structural models and non-rocking ones were nearly same at the elastic stage due to the reasonable design of rocking column base. The reduced beam sections (RBS) used at the beam-column joints could effectively control the damage location, and the liftable column bases with friction dampers could improve the energy absorption capacity of the rocking structure model. Comparing with the non-rocking models, the plastic damage on rocking specimens was greatly reduced under large lateral deformation. Furthermore, there was no local buckling on the structural elements of the rocking steel frame even under 2.5% drift ratio, which showed that the rocking structures with rational design would perform well under server seismic.

Owing to good self-lubricating performance, tin bronze is widely used in industrial fields. As tin bronze parts manufactured by powder metallurgy, their tribological performances are influenced by raw powder. In this work, four types of self-lubricating copper alloy composites (CuSn10 (D), CuSn10, CuSn10Pb10 (D) and CuSn10Pb10) were prepared by sintering completely alloyed powder and diffusion alloyed copper tin powder. The morphology, element distribution and microstructure of raw powder and their sintered Cu alloy composites were observed. The tribological properties of Cu alloys were investigated by block-ring friction test under different working conditions and their worn surface and wear debris were analyzed. The results show that the diffusion alloyed powder has an irregular dendritic morphology and its sintered Cu alloy is more likely to produce twin structure which enhances the hardness and the bearing capacity of the material. Compared with completely alloyed powder sintered CuSn10 sample, the wear rate of CuSn10 (D) sintered from diffusion alloyed powder was reduced by 83.96%, 74.39%, and 67.63% under three typical working conditions. Under dry friction conditions, the wear rate of CuSn10 (D) is reduced by 63.64% than CuSn10, and CuSn10Pb10 (D) is 25% lower than CuSn10Pb10. The investigation on the wear tracks and wear debris of Cu alloy composites showed that the diffusion alloyed powder sintered samples are inclined to form a more consecutive and integral third-body layer on wear tracks and which contributes to the better wear resistance.

Poor thermal stability and severe structural degradation of Ni-rich LiNi0.6Co0.2Mn0.2O2 (NCM622) cathode during the (de)lithiation process hinder its further application. As a typical thermal barrier material and ion conductor, La2Zr2O7 (LZO) was herein served as the multifunctional modification layer due to its excellent thermal stability, robust chemical stability, and prominent Li+ conductivity. Through optimizing the contents of LZO, 2 wt.% LZO-coated NCM622 (2LZO-NCM) displayed the much improved cycling stability (66.0% capacity retention at 0.2 °C after 300 cycles at 55 °C) and rate capability (73.0 mAh g−1 at 5 °C) as compared with the pristine NCM622 (59.3%, 22.4 mAh g−1). An aging test, differential scanning calorimetry research, and kinetics analysis were conducted to unveil the improvement mechanism of electrochemical performances for 2LZO-NCM, mainly owing to the relieved structure degradation, boosted thermal stability, and enhanced electrochemical kinetics after LZO modification, synergistically contributing to the improved electrochemical performances. This work provides a universal avenue to enhance the thermal stability and electrochemical performances of the NCM622 cathode via employing the thermal barrier material as a coating layer, even in other cathodes beyond NCM622.

Thermoplastic composites (TPCs) are promising materials for aerospace, transportation, shipbuilding, and civil use owing to their lightweight, rapid prototyping, reprocessing, and environmental recycling advantages. The connection assemblies of TPCs components are crucial to their application; compared with traditional mechanical joints and adhesive connections, fusion connections are more promising, particularly resistance welding. This study aims to investigate the effects of process control parameters, including welding current, time, and pressure, for optimization of resistance welding based on glass fiber-reinforced polypropylene (GF/PP) TPCs and a stainless-steel mesh heating element. A self-designed resistance-welding equipment suitable for the resistance welding process of GF/PP TPCs was manufactured. GF/PP laminates are fabricated using a hot press, and their mechanical properties were evaluated. The resistance distribution of the heating elements was assessed to conform with a normal distribution. Tensile shear experiments were designed and conducted using the Taguchi method to evaluate and predict process factor effects on the lap shear strength (LSS) of GF/PP based on signal-to-noise ratio (S/N) and analysis of variance. The results show that current is the main factor affecting resistance welding quality. The optimal process parameters are a current of 12.5 A, pressure of 2.5 MPa, and time of 540 s. The experimental LSS under the optimized parameters is 12.186 MPa, which has a 6.76% error compared with the result predicted based on the S/N.

SmBaCo2−x−yMnxMgyO5+δ (x = 0.5, 1, 1.5 and y = 0.05, 0.1) samples are synthesized by sol-gel method. The influence of different substitution of Mn and Mg for Co on crystal structures, thermal expansion coefficient (TEC), electrical conductivities and electrochemical performances have been investigated. The generation of the secondary phase BaMnO3 is suppressed with Mg2+ increasing. Demonstrated by temperature-dependent X-ray diffraction from 25 °C to 700 °C, the structure of SmBaCo0.4Mn1.5Mg0.1O5+δ in high temperature is stable. The TEC of SmBaCo1.45Mn0.5Mg0.05O5+δ, SmBaCo0.95MnMg0.05O5+δ, SmBaCo0.45Mn1.5Mg0.05O5+δ and SmBaCo0.4Mn1.5Mg0.1O5+δ are 15.77 × 10−6 K−1, 16.20 × 10−6 K−1, 12.19 × 10−6 K−1 and 12.58 × 10−6 K−1, respectively, which are much lower than those of cobalt-based layered perovskites and more compatible with the thermal expansion of SDC electrolyte. Although the electrochemical performances of SmBaCo2−x−yMnxMgyO5+δ (x = 0.5, 1, 1.5 and y = 0.05, 0.1) decrease slightly with Mn increasing, the polarization resistances of the SmBaCo1.45Mn0.5Mg0.05O5+δ and SmBaCo0.4Mn1.5Mg0.1O5+δ are 0.17 Ω cm2 and 0.30 Ω cm2 at 800 °C, respectively, which can meet the electrochemical performance requirements of cathode materials. Among the samples, the SmBaCo1.45Mn0.5Mg0.05O5+δ and SmBaCo0.4Mn1.5Mg0.1O5+δ show better tradeoff properties between TEC and electrochemical performance as cathode materials for IT-SOFCs.

Crystal copper nanocubes with different factors under triaxial tensions are studied by the molecular dynamics method. From stress-strain curve, yield stress and the damage models we can notice that decreasing the void size, increasing the strain rate and reducing the temperature can help to improve the strength of single crystal copper nanocube. Orientation is also a significant influence on the strength of the single crystal copper nanocube. A new porosity calculating method is presented based on the atomic number. Higher strain rates can harden the nanocubes. The dislocation atoms can easily slip under a high temperature. Nanomaterials are destroyed on account of coalescing voids.

Three hydrophilic polysiloxane–polyether block a-hydroxy alkylphenones macromolecular photoinitiators with ionic liquid character (SiE n Im-HHMP (n = 1, 3, 5) were designed and synthesized as a novel green photoinitiator based on polysiloxane, traditional photoinitiator 2-hydroxy-1-[4-(2-hydroxyethoxy) phenyl]-2-methyl propan-1-one (HHMP) and imidazolium. The photochemical properties, and photodegradation and photoinitiation mechanism of SiE n Im-HHMP (n = 1, 3, 5) were investigated by ultraviolet absorption spectroscopy, real-time infrared (RTIR) spectroscopy, electron spin resonance (ESR) and 1H-NMR. The SiE n Im-HHMP (n = 1, 3, 5) had good solubility in water and an absorption centered at 267 nm. The SiE n Im-HHMP (n = 1, 3, 5) not only can effectively initiate photopolymerization, but also have good thermal properties and low saturated vapor pressure. In addition, HPLC–MS chromatograms demonstrate that the migration of photolysis fragments of SiE n Im-HHMP (n = 1, 3, 5) from the cured material was alleviated significantly due to their high molecular weight. The cured films initiated by SiE n Im-HHMP (n = 1, 3, 5) have good thermostability compared with that by HHMP. More importantly, antibacterial tests of the films prepared using SiE1Im-HHMP against Escherichia coli and Staphylococcus aureus bacteria strains proved that SiE1Im-HHMP possesses effective antibacterial activity. The SiE n Im-HHMP (n = 1, 3, 5) exhibits promise in preparing green materials and antibacterial materials.

At present, a lot of attention has been paid to the reasonable design and synthesis of materials with core shell structure for high-performance supercapacitors. Herein, the Co3O4@MnO2 core shell arrays on nickel foam are successfully synthesized via a facile and effective hydrothermal method followed with annealing process. The sample was characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Electrochemical performance of the Co3O4@MnO2 material was studied using cyclic voltammetry, charge/discharge cycling, and electrochemical impedance measurements in 6 mol L−1 KOH aqueous electrolyte. The results indicated that the Co3O4@MnO2 material presented excellent electrochemical performance in terms of specific capacitance, cyclic stability, and charge/discharge stability.

Herein, 2D g-C3N4 nanosheets was successfully prepared by two processes: acid treatment and liquid exfoliation. The thickness of the nanosheets was nearly 4.545 nm containing ∼13 C-N layers. The acid treatment process before liquid exfoliation for bulk g-C3N4 could effectively destroy the in-plane periodicity of the aromatic systems and made the bulk easily exfoliated. This work carefully discussed the acid treatment effect for bulk by XRD patterns, nitrogen adsorption-desorption isotherm, FT-IR spectra, and UV–vis–NIR absorption spectra. Moreover, the nanosheets was fabricated and transferred onto FTO substrates by vacuum filtration self-assembled method to carefully investigate their optical, electrical, and photoelectrochemical properties. The thin film filtrated by 2 ml g-C3N4 nanosheets supernatant showed the best photocurrent response nearly 0.5 μA/cm2 and the lowest resistance of charge transfer (Rct) at the interface between FTO and electrolyte. The photocurrent response could be further effectively improved from nearly 0.5 to 1.8 μA/cm2 by the integration of CNTs to promote charge separation and transfer. Thus, the easy, safe, and indirect synthesis of 2D g-C3N4-based nanosheets thin films opens new possibilities for the fabrication of many energy-related devices.

The single crystal nanorods under uniaxial loading and unloading tensile with different period along crystallographic orientations [1 1 0] and axial directions being applied constant tensile rates are simulated respectively by method of molecular dynamics to elucidate the effect of periodical tensile stress and another mechanical properties of the single crystal copper within the Nano-scope. After stimulation, we compare the different features and phenomenon between the loading style of period and none of period. In the case of periodical loading, nanorods show the various maximum stress at yielding stage, and after yield, the degree of fatigue depends on the period of step heavily. Our results suggest that the mechanical character of single crystal copper nanorods is remarkably influenced by the steps of loading period when we use the maximum yield stress σs at none of periodical loading condition as underlying reference. At the following text description, it has been expressed that the total number of loading and unloading circle may affect the mechanical response of the MD system. When the semi-periodical loading steps or the total steps of whole periodical load near to 5.1 × 103 steps (8.7 × 103 steps for the other model), the model system occurs to the Nano-scale fatigue. And the Nano-scale fatigue will lead to the yield point decreasing in turn on account of various periodical steps. Keywords: Molecular dynamics, Single-crystal copper, Different periodical load, Uniaxial loading, Nanoscale fatigue, Different axial length

&ldquo, Tube beams&rdquo, are common lightweight structures, which have domestic and industry applications, and are often subjected to complex multidirectional loads. Therefore, metals with mature manufacturing methods and isotropic properties are commonly used in the fabrication of these structures, which are preferred to be lighter in weight. Although polymer matrix composites are generally used for weight reduction, their conventional manufacturing methods, such as pultrusion and filament-winding, cannot meet the isotropic requirements. Moreover, research on bent tube beams (elbows) is rare. Therefore, a self-made glass fiber/epoxy polyvinyl ester fabric prepreg and a self-designed mold were used in this study to prepare an isotropic composite double-bent elbow by a silicone rubber airbag-assisted process. The load capacity of the elbow was tested and validated by the finite element method. A strength and deformation of up to 3448 N and 2.84 mm respectively, were achieved. The simulation and experimental results were consistent: the error for the load capacity and deformation was only 4.15% and 7.75% respectively, under the max stress criterion.

In the paper, copper nanorods with different orientations and different lengths are simulated with applying the uniaxial compression load by the molecular dynamics method. Dynamic Poisson’s ratio and dynamic Young’s modulus of the nanorods at the process of the simulations are discussed. Aiming to a rigorous research, the tensile nanorods and the compressed nanorods are compared first. When a nanorod is compressed, there is a jump phenomenon in the changing process of dynamic Poisson’s ratio and dynamic Young’s modulus. The sequential order of jumps appearing is associated with the crystal orientation and the length of the nanorods. The smaller the orientation size is, the earlier the jump occurs. The compressed nanorod is stable when the size ratio of a nanorod is suitable and, simultaneously, the jump ranges of both Poisson’s ratio and Young’s modulus are the lowest.

To theoretically study the stability and the heterogeneous nucleation characteristics of γ-Fe/Cu interface in steel/copper bimetallic, the six surface models and seven interface models were investigated through density functional theory. Besides, the interface stability, adhesion energy, electronic properties, tensile process and fracture behavior of three kinds typical Fe/Cu interface model were calculated by first-principles calculations. Simultaneously, the mechanism on heterogeneous nucleation of pure Fe on Cu-based alloy was revealed. The results indicate that the bramfitt’s lattice mismatches of all the three Fe/Cu interfaces were both 4.11%, and all the Cu surfaces and the Fe surfaces were trends to converge, when the number of layers were 9 and 7, respectively. Among three kinds Fe/Cu interfaces with HCP structure, the Fe (1 1 0)/Cu (1 1 0) interface shown higher strength of metallic bonds and stable ionic properties. When the strain is 37%, the maximum value of the tensile stress is about 20.3GPa and the electron density between Fe and Cu atoms drop to disappear. The calculated adhesion work of Fe (1 1 0)/Cu (1 1 0) interface with HCP structure is 1.88 J/m2, is higher than that between Cu/Cu melt (1.78 J/m2), which proved that the Fe particles can promote heterogeneous nucleation of Cu atoms and then account for the grain refinement of Cu-based alloy.

Highly uniform and well dispersed CaF2 hollow spheres codoped with rare-earth (RE) ions Ce3+ and Yb3+ were synthesized by a facile and effective hydrothermal approach based on Ostwald ripening mechanism. The chosen phosphors were added in the SiO2 sols so as to get the anti-reflection (AR) coatings with wavelength conversion property, further to availably enhance the photovoltaic performance of solar cells. The ultraviolet (UV) light excitation induced the transition from 5D to 4F energy levels of Ce3+ with two emission bands centering at 317 nm and 336 nm. Through an efficient energy transfer process, the intense characteristic near-infrared (NIR) emission of Yb3+ peaking at 965 nm and 1026 nm attributed to the transition of 2F5/2 to 2F7/2, which is just matched the spectral response of Si band gap. In addition, all of the AR coating films containing phosphors showed an incredible transmittance performance in visible and NIR region as well as a preferable photo-electricity response. CaF2:Ce3+–Yb3+ AR coating film could effectively improve the photoelectric conversion efficiency by 0.16%, 0.50% and 1.20% compared to CaF2:Ce3+ AR coating film, SiO2 AR coating film and pure glass respectively. This work may promote a new platform and wider application of the wavelength conversion materials for silicon solar cells.

Two-dimensional cobalt–manganese binary metal oxides (Co1.5Mn1.5O4) porous nanosheets have been successfully synthetized via a simple liquid phase precipitation method. This thin nanosheet structure can shorten the electrolyte ion diffusion distance. Meanwhile, the abundant mesoporous provides more electrochemical active sites, facilitates ion diffusion, and reduces the volume expansion in the charge/discharge cycling processes. Furthermore, there is a synergistic effect on the electrochemical reaction of Co1.5Mn1.5O4. Owe to the high electrical conductivity, cobalt can decrease the impedance and expedite charge transfer. In return, manganese contributes more capacitance in the binary metal oxides. As a result, the as-prepared Co1.5Mn1.5O4 porous nanosheets exhibit outstanding electrochemical performances, such as a specific capacitance of as high as 472.5 F g−1 at 0.5 A g−1, excellent rate capability of 338.5 F g−1 at 10 A g−1 which is equivalent to about 71.6 % of the capacitance at 0.5 A g−1, and long-term cyclability of almost 100 % capacity retention after 1000 cycles.

To better understand flow and heat transfer in the fractured rock in enhanced geothermal systems (EGS), experiments were conducted to investigate the single-phase convective heat transfer and pressure drop of water flowing through a single fracture in a cylindrical granite rock. Dimensionless correlations for the Poiseuille number (Po) and the average Nusselt number (Nu) with the Reynolds number (Re) were obtained from the experimental data. It was found that the experimental results significantly deviated from those of rectangular macrochannel flows, and the flow friction is raised and the heat transfer is weakened significantly due to the large relative roughness. As confining pressure is applied, reduction of the aperture raises both Po and Nu. A roughness–viscosity model (RVM) was employed to account for the effects of the surface condition, and a satisfactory agreement between the numerical results based on RVM and the experimental data was achieved.

This paper reported a water-borne polysiloxane-modified benzophenone macromolecular photoinitiator (WPSHBP), whose characteristics of the photopolymerization, the migration of photolysis fragments, the volatility, and reduction of oxygen inhibition were discussed in detail. WPSHBP has a maximum absorption peak at 286 nm, and the molar extinction coefficient (e286 nm) is 23200 M−1 cm−1. The photopolymerization rate and final double bond conversion of the system initiated by WPSHBP were enhanced with the increasing contents of triethanolamine (TEOA) and WPSHBP and irradiation intensity. WPSHBP exhibits a low migration of photolysis fragments and volatility compared with small-molecular photoinitiator benzophenone (BP). The cured films initiated by WPSHBP have good mechanical properties and thermostability compared with that by 2-hydroxy-4’-(2-hydroxyethoxy)-2-methylpropiophenone (Irgacure 2959). More importantly, the water-borne polysiloxane-modified photoinitiator can mitigate the oxygen inhibition...

In this work, we utilized hydrothermal treatment method to prepare a new type of nanomaterial MoS2/reduced graphene oxide (RGO) heterojunction with the graphite oxide assisted since it can provide the oxygen containing functional groups for MoS2 precusor to attach. The morphologies and microstructures of as prepared products are characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Raman spectra and X-ray photoelectron spectroscopy. It is found that the MoS2 nanosheets have about seven layers which revealed the possibility of using RGO as an ideal support material for forming fewer layered MoS2 nanosheets. In addition, the obtained MoS2/RGO nano heterojunction exhibit preferable electrical conductivity and photocurrent response activity under the illumination of simulated sunlight compared to pure MoS2.

In this work, metallic silver co-doped Y 2 O 3 :Tb 3+ , Yb 3+ near-infrared quantum cutting material was synthesized through a conventional coprecipitation method. Its microstructure and optical properties were characterized, and the fluorescence enhancement of Tb 3+ , Yb 3+ by silver nanoparticles (Ag NPs) was investigated. The highest fluorescence intensity is achieved with the Ag doping concentration of 0.10%, which can enhance the emission of Tb 3+ by 88% in the visible region and Yb 3+ by 47% in the near infrared region. The present results indicate that the fluorescence enhancement is attributed to the local field enhancement by Ag NPs which influence the energy transfer occurring between 5 D 4 of Tb 3+ and 7 F 5 of Yb 3+ .