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A small blind internal thread (SBIT) is used to firmly fasten some functional components to the cover of 3C electronic products. The small internal thread is made in a blind hole using a fluteless forming tap (FFT) that does not produce chips. However, the four geometric parameters (tool width (W), tooth root diameter (D2), front-end diameter (Df) and tooth angle (θ)) for the FFT affect the thread filling rate (f) and the minimum torque (T) for the tapping process. This study reports a Box-Behnken design (BBD) using DEFORM-3D (finite element model) and MINITAB (regression analysis) software to tap 7075-T6 aluminum alloy using a small FFT to achieve a repeatable thread filling rate and minimum torque. The experimental results show that the BBD accurately predicts and simulate the thread filling rate for tapping 7075-T6 aluminum alloy. The modelling software and the experimental design for this study can be used to optimize the design of tools that are used in industrial production.

Photocatalysis is regarded as one of the most promising technologies to remove organic contaminants. At present, most of the covalent organic frameworks (COFs) used as photocatalysts are connected by imine or borate bonds, which have relatively low stability and relatively poor π-delocalization. Herein, we report, for the first time, vinylene-linked COFs constructed by various diacetylene and triazine moieties for photocatalytic degradation of organic contaminants and disinfection of bacteria. The pioneering introduction of diacetylene moieties not only enhances conjugated π-electrons delocalization but also optimizes the electronic band structures that significantly improve photocatalytic activity. Therefore, the vinylene-bridged COFs have excellent photocatalytic activity with ultrahigh stability and great π-electron delocalization, thus exhibiting ultrafast photocatalytic degradation efficiency for phenol and norfloxacin (96%, within 15 min). Our work provides a strong basis for the rational regulation of the chemical structure of COFs to enhance their photocatalytic activity, thus broadening the application of COFs in photocatalysis.

The hybrid electrode of single-wall carbon nanotubes (SWCNTs)/Cu2O/ZnO nanorods (NRs)/graphene used on the current-response nonenzymatic glucose sensor was investigated herein, regarding the mechanism of the formation of functional channel. The synthesis of the hybrid electrode involved four steps. First, the graphene was grown by chemical vapor deposition (CVD) and then wet-transferred onto indium transparent oxide (ITO) glass. Second, a zinc oxide (ZnO) seed layer was sputtered onto the graphene/ITO glass, and ZnO NRs were gradually grown by the hydrothermal method. Third, the ZnO NRs were clad with cuprous oxide (Cu2O) by the electrochemical method. Fourth, the SWCNTs were dropped onto the Cu2O surface, with a Nafion surfactant. X-ray diffraction spectra, scanning electron microscopy spectra, Raman spectra, cyclic voltammograms, and amperometric response diagrams were used to verify the performance of the device. Results showed that sensitivity increased significantly from 11.2 to 289.8 μA mM-1 cm-2, linear range increased significantly from 0.6 to 11.1 mM, and the coefficient of determination (R2) increased from 0.9766 to 0.9923, all by the addition of the SWCNTs/Cu2O functional channel mechanism and without graphene. When the graphene was added to the functional channel electrode, sensitivity increased again from 289.8 to 466.1 μA mM-1 cm-2 at low concentrations.

The fatigue behavior of asphalt mixture is the main reason that affects the service performance and service life of asphalt pavement. The fatigue mechanism of asphalt mixture is still unclear. In fact, the fatigue damage of asphalt mixture is mainly related to the nature of asphalt binder. Therefore, the study of the damage of asphalt binder is beneficial to reveal the fatigue failure mechanism of asphalt mixture. At present, there is no clear damage behavior method of asphalt binder. Considering that the damage behavior of asphalt binder is actually related to its rheological behavior, the shear rheological method is used to evaluate the damage behavior of asphalt binder. The complex modulus is used as the evaluation index of asphalt damage behavior. Because the strain loading mode is consistent with the actual force of the binder in the asphalt mixture. The damage behavior of asphalt binder is studied by time scanning mode under controlled-strain mode. The influence of temperature, loading frequency, and other parameters on the damage behavior of asphalt binder is analyzed. Through the data analysis, the asphalt damage curve meets Boltzmann distribution. At the same time, the characteristics of asphalt damage curve are analyzed. It is proposed that there are three inflection points and two platforms for the typical damage curve of asphalt binder. The three inflection points divide the damage behavior of asphalt into elastic deformation stage, yield stage, crack growth stage, and failure stage. The effects of temperature and loading frequency on the curve characteristics are summarized. For asphalt binder with higher stiffness, the damage curve of asphalt binder is “L” type when the strain level and loading frequency are larger. When the temperature is higher, the loading frequency is smaller, and the strain is smaller, the damage curve will gradually change to anti-“S” type or even linear.

Covalent organic frameworks (COFs) with stable long-range ordered arrangements are promising materials for organic optoelectronics. However, their electrochemiluminescence (ECL) from non-ECL active monomers has not been realized. Here, we report a design strategy for ECL-emitting COF family. The donors and acceptors co-crystallized and stacked into the highly aligned array of olefin-linked COFs, so that electrons can be transported freely. By this means, a tunable ECL is activated from non-ECL molecules with the maximum efficiency of 32.1% in water with the dissolved oxygen as an inner coreactant, and no additional noxious co-reactant is needed any more. Quantum chemistry calculations further demonstrate that this design reduces the COFs' band gaps and the overlap of electrons and holes in the excited state for better photoelectric properties and stronger ECL signals. This work exploits a basis to envisage the broad application potential of ECL-COFs for various biosensors and light-emitting display.

The nonaqueous lithium–oxygen batteries have attracted considerable interest because of the ultrahigh theoretical capacity. However, the overpotential and cyclability issue of lithium–oxygen battery caused by interfacial issue limits its commercialization. To overcome these challenges, redox mediators, which are capable of charge transport on the electrode/electrolyte interfaces, are introduced to lithium–oxygen batteries to reduce overpotential. This review provides a detailed summary of the interfacial reaction mechanism and the influence of redox mediators on the electrode/electrolyte interfaces. Researches on suppressing redox mediators’ shuttle effect are also beneficial to enhance the electrochemical performance of lithium–oxygen batteries.

Electrochemiluminescence (ECL) plays a key role in analysis and sensing because of its high sensitivity and low background. Its wide applications are however limited by a lack of highly tunable ECL luminophores. Here we develop a scalable method to design ECL emitters of covalent organic frameworks (COFs) in aqueous medium by simultaneously restricting the donor and acceptor to the COFs’ tight electron configurations and constructing high-speed charge transport networks through olefin linkages. This design allows efficient intramolecular charge transfer for strong ECL, and no exogenous poisonous co-reactants are needed. Olefin-linked donor-acceptor conjugated COFs, systematically synthesized by combining non-ECL active monomers with C2v or C3v symmetry, exhibit strong ECL signals, which can be boosted by increasing the chain length and conjugation of monomers. The present concept demonstrates that the highly efficient COF-based ECL luminophores can be precisely designed, providing a promising direction toward COF-based ECL phosphors., Electrochemiluminescence (ECL) plays a key role in analysis and sensing but its application is limited by a lack of highly tunable luminophores. Here, the authors demonstrate the design of high efficient ECL luminophores of covalent organic frameworks (COFs) in aqueous media by simultaneously restricting the donor and acceptor to the COFs’ electron configurations and constructing charge transport networks through olefin linkages.

Energy and fresh water are essential for the sustainable development of human society, and both could be obtained from seawater. Herein, we explored the first covalent organic framework (COF) sponge (named BHMS) by in situ loading the benzoxazole-linked COF (DBD-BTTH) onto a porous polymer scaffold (polydimethylsiloxane) as a synergistic platform for efficient solar desalination and selective uranium recovery. In natural seawater, BHMS shows a high evaporation rate (1.39 kg m-2 h-1) and an exceptional uranium recovery capacity (5.14 ± 0.15 mg g-1) under 1 sun, which are due to its desirable inbuilt structural hierarchy and elastic macroporous open cells providing adequate water transport, increased evaporation sites of seawater, and selective binding sites of uranyl. Besides, the excellent photothermal performance and photocatalytic activity endow the BHMS with high solar desalination efficiency and excellent anti-biofouling activity and promote selective coordination of uranyl.

Covalent organic framework nanosheets (COF NSs) provide well-ordered π–π structures that can be used to develop luminescent materials. However, most COF NSs have problems of weak luminescence and l...

Covalent organic frameworks (COFs) have shown extensive applications in energy storage, catalysis, and gas adsorption because of their regular pore structure, flexible topological connectivity, and...

Swelling, mechanical strength, flexibility, and toughness are important parameters in hydrogel preparation for application in the human body. Herein, composite hydrogels were prepared using a mix of Konjac glucomannan (KGM), sodium alginate (SA), and polyvinyl alcohol (PVA) cross-linked by calcium hydroxide. The PVA/KGM/SA composite hydrogel showed a suitable swelling ratio and rate, as well as elasticity and flexibility. In addition, the elongation at break was 660.3%, with a breaking strength of 87.25 kPa and a compression modulus of 1.660 MPa. Rheological studies showed that the composite hydrogel was composed of a multiply cross-linked network involving chemical and physical interactions, thereby affecting the elasticity and flexibility of the gel. Interestingly, the composite gel network was reformed when the temperature decreased. In rabbit models of dry eye, the hydrogel effectively maintained the normal tear meniscus height and increased the low tear meniscus area. The results therefore showed that the PVA/KGM/SA gels not only provide a simple, effective, and safe method for the preparation of hydrogels, but also have potential applications in the treatment of dry eye syndrome.

The magnesium-gadolinium (Mg–Gd) system provides an ideal model alloy for precipitation hardening. Evolution of precipitates in a Mg–16.2Gd–0.4Zr (wt.%) alloy during isothermal ageing from 150 °C to 300 °C was systemically studied using high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). The widely accepted four-stage precipitation sequence of the Mg–Gd(–Zr) alloy system has been accordingly updated to: super-saturated solid solution (S.S.S.S.) → ordered solute clusters → GP zones → β′ → β F ' + tail-like hybrid structures → β1 → β. In addition to carefully revealing an updated precipitation sequence, new insights into the relationships amongst different precipitate phases were obtained and rationalised. (1) Solute clusters and GP zones form during the early stages of ageing and share the same structural unit; (2) Formation of β′ phase is accomplished via ordered stacking of zigzag GP zones along " open=" 10 1 ¯ 0 α; (3) Coarsening of β′ phase promotes the formation of β F ' phase and tail-like hybrid structures; (4) β F ' phase facilitates the nucleation of β1 phase; and (5) β1 and β phases maintain a low-energy Σ9 interface and β1 phase finally transforms to equilibrium β phase in situ. The precipitate evolution at the grain boundaries during ageing were also investigated and grain boundary precipitate free zones were observed in Mg–16.2Gd–0.4Zr alloy aged at 250 °C or above.

This paper studied the role of bimodal-grained structure in strengths and asymmetry behaviors of Mg-15Gd-1Zn-0.4Zr (wt%) alloys under the as-extruded, compressive-yielded and fractured conditions. The bimodal-grained structure consisting of fine recrystallized grains and coarse un-recrystallized grains formed when the alloys were extruded with relatively low temperature. Compared with the equiaxed structure, the bimodal-grained structure possessed higher tensile strength attributed to the fine recrystallized grains plus the strong and hard un-recrystallized texture with its basal planes nearly parallel to the loading direction. However, the bimodal-grained structure weakened the ultimate compressive strength, because the un-recrystallized texture is favorable for tensile twining in the compressive test. Eventually, the aged sample with the bimodal-grained structure exhibited ultra-high tensile yield strength and ultimate tensile strength of 465 MPa and 524 MPa, respectively. Especially, the inhomogeneous bimodal-grained structure with stronger texture resulted in extraordinary low compressive-tensile yield asymmetries of 0.99 and 0.98 compared with those (from 1.09 to 1.48) of the homogeneous equiaxed structures with relatively random textures, because the fine recrystallized grains in the bimodal-grained structure undertook major deformation by slips and suppressed twining before the yield points in the mechanical tests. The relationship between the microstructures and properties allows us to produce high tensile strength Mg components by applying low extrusion temperature and obtaining bimodal-grained structure.

Based on density functional theory(DFT), using virtual crystal approximation and generalized gradient approximation(GGA)with pseudopotential method, the lattices and energies for five crystallines of vanadium hydrides are optimized and calculated. The phonon densities of states are calculated based on density functional perturbation theory(DFPT). The standard Heat capacities, Entropies, Helmholtz free energies and Gibbs functions of vanadium and its hydride are deduced at 298.15K. The calculated results are discussed and compared with experimental data.

Summary: It is hard to find new electrochemiluminescence (ECL) luminophores using existing research strategies, especially from ECL non-active monomers. Here, fully conjugated covalent organic frameworks with trithiophene (BTT-COFs) are found to have ultra-high ECL efficiencies (up to 62.2%), even in water and without exogenous co-reactants. Quantum chemistry calculations confirm that the periodic BTT-COFs arrays promote intramolecular electron transfer generating ECL from non-ECL monomers. Modulation of ECL performance is possible by substituting the monomers for those with different electron-withdrawing properties. In addition, the cyano group weaved in the skeleton provides the dense sites for post-functionalization. As a typical use case, a highly selective ECL probe for uranyl ions is reported. The tunable ECL luminophore family possesses a broader development space than the traditional emitters, demonstrates the prospects of ECL-COFs, and affords an idea for detecting various contaminants through the rational design of target ligands.

Capturing of uranium from the natural seawater is considered to be one of the most promising methods to meet the current demand for nuclear energy. Herein, we prepared a reduced graphene oxide-based (rGO-based) covalent organic framework hydrogel (KTG) with three-dimensional porous structure as a platform for enhancing uranium capture capacity through photothermal desalination. Under light irradiation, the KTG produces a local heat that can be used to generate steam while promoting the rapid diffusion of uranium inside the hydrogel 3D network, thereby increasing the adsorption efficiency and capacity of uranium. KTG can achieve exceptional uranium capture capacity (521.6 mg g−1) under one sun irradiation, which is 42.4% higher than that under dark conditions. In addition, excellent photocatalytic activity and mechanical properties make KTG possess high anti-biofouling activity, good reusability, and achieving continuous uranium capture and solar distillation.

Photocatalysis is a potential technology for removing pollutants from water. As the recombination of the photogenerated electron-hole pairs can hinder the photocatalytic efficiency in the treatment of wastewater, the surface of the carrier is usually coated with a semiconductor. In this study, carbon microtube electrode prepared from corncob was coated with either titanium oxide (TiO2) or bismuth phosphate (BiPO4) and then used as a photocatalyst (C–TiO2 or C–BiPO4) to investigate the photodegradation of methylene blue (MB). The two photocatalysts, C–TiO2 and C–BiPO4, were characterized by phase determination, microstructure observation, water contact angle measurement, and base site analysis. The influences of reaction time, stability, MB concentration, initial pH, and OH radicals quenching on the degradation of MB were also evaluated. The degradation of MB by C–TiO2 and C–BiPO4 was mainly dominated by OH radical oxidation. The carbon microtube increased both the mass transfer rate and the photogenerated electron-hole pairs separation rate, thereby increasing the photocatalysis of both C–TiO2 and C–BiPO4 as revealed by an increase in the rate of MB degradation. The rate constants obtained for the degradation of MB by C–TiO2 and C–BiPO4 at 20 °C were 9.739 × 10−7 mM min−1 and 1.111 × 10−7 mM min−1, respectively. The coating of TiO2 and BiPO4 on the surface of the carbon microtube electrode enhanced their photocatalytic performance, and therefore, C–TiO2 and C–BiPO4 could be developed into a novel material to be used in the photodegradation of dye pollutants.

Transport and separation of binary mixtures of active and passive particles are investigated in the presence of temperature differences. It is found that temperature differences can strongly affect the rectification and separation of the mixtures. For active particles, there exists an optimal temperature difference at which the rectified efficiency is maximal. Passive particles are not propelled and move by collisions with active particles, so the response to temperature differences is more complicated. By changing the system parameters, active particles can change their directions, while passive particles always move in the same direction. The simulation results show that the separation of mixtures is sensitive to the system parameters, such as the angular velocity, the temperature difference, and the polar alignment. The mixed particles can be completely separated under certain conditions.

Mg-Gd and Mg-Y are two fundamental Mg alloy systems. Four alloys with a equi-concentration of total alloying elements: Mg-2.8Gd-0.1Zr (at%), Mg-2.4Gd-0.4Ag-0.1Zr (at%), Mg-2.8Y-0.1Zr (at%) and Mg-2.4Y-0.4Ag-0.1Zr (at%) were designed. The roles of Ag in the Mg-Gd and Mg-Y alloys were comparatively studied. The Ag addition enhances the age-hardening response of the Mg-2.4Gd-0.4Ag-0.1Zr due to a combined strengthening effect of the prismatic β′ and basal γ′′ precipitates. In contrast, the Mg-2.4Y-0.4Ag-0.1Zr exhibits a weakened age-hardening response in comparison with the Mg-2.8Y-0.1Zr, which is due to the formation of the basal γ′′ precipitates at the expense of the prismatic β′ precipitates. The Ag addition also promotes the formation of precipitation free zones (PFZs) along grain boundaries in both Mg-2.4Gd-0.4Ag-0.1Zr and Mg-2.4Y-0.4Ag-0.1Zr. The grain boundary PFZ is supposed to relax stress concentration to some extent during plastic deformation, which is beneficial to ductility. In summary, the Ag addition not only improves the tensile yield strength (YS) and ultimate tensile strength (UTS), but also improves the elongation of the Mg-2.4Gd-0.4Ag-0.1Zr. In comparison, the Ag addition in the Mg-2.4Y-0.4Ag-0.1Zr improves the UTS and elongation but reduces the YS in comparison with the Mg-2.8Y-0.1Zr. The results in this study suggest that Ag is more effective to strengthen Mg-Gd than Mg-Y alloys.

Microstructural evolution of Mg–15Gd–1Zn–0.4Zr (GZ151K, wt%) alloys, cast under 0 MPa (gravity cast) and 6 MPa (squeeze cast), were comparatively studied. It is found that the grain size of squeeze cast GZ151K alloy with applied stress 6 MPa is much smaller than that of the gravity cast counterpart. Moreover, the squeezing pressure hinders the transition from β' precipitates to β1 precipitates during subsequent aging process, leading to reduced volume fraction of β1 precipitates in the squeeze cast alloy. Thus, the relatively lower volume fraction of β1 precipitates in the squeeze cast GZ151K results in higher hardness increment and stronger precipitation hardening effect. Keywords: Mg–Gd–Zn–Zr alloy, Squeeze casting, Microstructure, Precipitation hardening

The present paper reports a quasi-in-situ STEM-EDS approach for studying the role of Ag in the corrosion behaviour of Mg-Gd-Zr alloys. Following corrosion, the segregation of O at the interface of the α-Mg matrix and the β phase was observed. Furthermore, Ag-rich particles and the re-deposition of Ag were also observed on the nanoscale. Based on quasi-in-situ STEM-EDS observations herein, the partitioning of Ag into the β phase leads to enhanced localised corrosion, whilst the subsequent formation of Ag-rich particles during the corrosion process leads to enhanced rate of corrosion propagation, with accompanying oxy-hydroxide formation observed upon the Mg-Gd-Ag-Zr.

In order to expand the application of the basic magnesium carbonate in the field of flame retardant, the plate-like basic magnesium carbonate (Mg5(CO3)4(OH)2.4H2O) was prepared successfully by template-mediated/ homogeneous precipitation method, using magnesium chloride hexahydrate (MgCl2.6H2O) and urea (CO(NH2)2) as reaction materials. Phase and morphology of the product were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and atomic force microscope (AFM), respectively. The results showed that well-crystallized plate-like Mg5(CO3)4(OH)2.4H2O can be prepared at the water bath temperature of 100 °C, water bath time of 24 h, the aging time of 5 h after adding organic template agent. The investigation on organic template mediated mechanism shows that the template affects the crystal morphology by changing surface energy of different crystal plane. Through a preliminary study on the growth mechanism of the product, it is found that the generation of the plate-like Mg5(CO3)4(OH)2.4H2O could be explained by two-dimensional nucleation/step growth mechanism.

Using non-equilibrium molecular dynamics and Monte Carlo methods, we have studied the transport diffusion of gas in deformed carbon nanotubes. Perfect carbon nanotube and various deformed carbon nanotubes are modeled as transport channels. It is found that the transport diffusion coefficient of gas does not change in twisted carbon nanotubes, but changes in X Y -distortion, Z -distortion and local defect carbon nanotubes comparing with that of the perfect carbon nanotube. Furthermore, the change of transport diffusion coefficient is found to be associated with the deformation factor. The relationship between transport diffusion coefficient and temperature is also discussed in this paper. Our results may contribute to understanding the mechanism of molecular transport in nano-channel.

The evolution of precipitates in a high-strength Mg-2.4Gd-0.4Ag-0.1Zr (at. pct) alloy was investigated using high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). The precipitation of Mg-2.4Gd-0.4Ag-0.1Zr includes β- and γ-type precipitates, the latter involving a hitherto unreported precipitation sequence that is the focus of the present study. The β-type precipitation sequence is described as follows: supersaturated solid solution (S.S.S.S.) → ordered solute clusters → zigzag GP zones → β′ → $$ \beta_{F}^{'} $$ → β 1 → β. Compared with the precipitation sequence of the Mg-Gd system, the proposed β-type precipitation sequence includes ordered solute clusters, zigzag GP zones, and $$ \beta_{F}^{'} $$ , but excludes β″. The strain field around the coarsened β′ phase is supposed to stimulate the formation of the $$ \beta^{\prime}_{F} $$ phase. Furthermore, the $$ \beta_{F}^{'} $$ phase provides preferential nucleation site for the β 1 phase. The γ-type precipitation sequence is proposed as follows: S.S.S.S. → basal GP zones → γ′′′ → γ″ → γ. The crystal structures, morphologies, and orientations of the basal GP zone, γ′′′, γ″, γ phases were comprehensively examined and established herein. The results are described in the context of other, but similar, alloy systems. A holistic description of the precipitate evolution in Ag-containing Mg-Gd alloys is discussed and rationalized.

In this paper, the electronic structure and photo-electric properties of N and Fe co-doped ZnO systems have been studied by using Density functional theory method. The results show that the formation energy of ZnO-N, ZnO-Fe, ZnO-N-Fe and ZnO-N-2Fe systems decreases in turn, the doping is easier to realize. Compared with the ZnO system, the activity of ZnO-Fe, ZnO-N-Fe and ZnO-N-2Fe systems increases in turn, the band gap of ZnO-N and ZnO-N-2Fe systems decreases, and the electron transition is easier in the doped system. The peak of the dielectric function shifts to the left, the absorption of the electron to the photon increases obviously, and the absorption spectrum appears red shift. It can be concluded that the electronic structure and optical properties of ZnO are greatly affected by the single and co-doping of N and Fe, which provides a theoretical basis for the further study.

In this paper, the electronic structure and photoelectric properties of P and Cu doped ZnO systems have been studied by Density functional theory method. The results show that the formation energies of ZnO-P-Cu, ZnO-P-2Cu, ZnO-P and ZnO-Cu systems decrease in turn Compared with the intrinsic ZnO system, the ZnO-P, ZnO-P-Cu, ZnO-P-2Cu and ZnO-Cu systems have higher activity, the band gap of ZnO-P and ZnO-P-2Cu systems is reduced, and the electron transition is easier. In the doped system, the peak of the dielectric function shifts to the left and increases, the absorption of the electron to the photon increases obviously, and the absorption spectrum appears red shift, from the calculated results, it can be concluded that P and Cu single-doped and co-doped ZnO have great influence on the electronic structure and optical properties of ZnO system, which provides a theoretical basis for further study of the influence of doping on the properties of ZnO.

A high-strength Mg-Gd-Zn-Zr alloy developed by a novel extrusion method called differential-thermal extrusion (DTE) was detailed characterized, to reveal the effects of the DTE on microstructure and mechanical properties. Different from traditional isothermal extrusion (ITE) with the same billet and mold temperature, the billet temperature for the DTE is remarkably higher than the mold temperature. The finer grains and less long period stacking ordered (LPSO) structure in the DTE sample resulted from its higher cooling speed after deformation. Meanwhile, the stronger precipitation strengthening effect was caused by the higher billet preheat temperature which reserved the precipitation ability before extrusion. As a result, the finer grains and stronger precipitation strengthening led to the strong tensile yield strength (380 MPa) and ultimate tensile strength (461 MPa) of the aged DTE sample, while those of the aged ITE sample are only 338 MPa and 420 MPa, respectively. The higher strengths indicate the DTE is a better extrusion process for producing high-strength Mg alloys than the traditional ITE.

The microstructures, phase constitutions and mechanical properties of as-cast samples, extruded rods and plates of Mg-3.52Sn-3.32Al and Mg-6.54Sn-4.78Al alloys were investigated by optical microscopy, scanning electron microscopy, X-ray diffraction and mechanical testing. The results show that as-cast microstructure consists of α-Mg matrix, Mg2Sn and a few dispersed β-Mg17Al12 phases. The two as-cast alloys exhibit good tensile mechanical properties. After hot extrusion, dynamic recrystallization occurs. Average grain size reaches 6 μm ~ 8 μm for rods, and a lot of fine micro-scaled particles exist, resulting in significant enhancement of tensile mechanical properties. The extruded Mg-3.52Sn-3.32Al rod exhibits better comprehensive tensile mechanical property than AZ31B alloy, with tensile strength σb of 295 MPa, yield strength of 200 MPa and elongation of 21.5% at ambient temperature. The extruded Mg-6.54Sn-4.78Al rod exhibits equivalent comprehensive tensile mechanical properties with ZK60 alloy, achieving tensile strength of 355 MPa, yield strength of 275 MPa and elongation of 11% at ambient temperature. The extruded plates at ambient temperature performed a tensile strength of 270 MPa.

1 wt.% Zn addition introduced additional basal γ′ precipitates to the Mg-15Gd-0.4Zr (wt.%) alloy. Based on the detailed analysis of the precipitates and tensile properties evolution of the alloys, the composite β′ and γ′ precipitates provided much stronger strengthening effects than the only β′ precipitates, even when the latter one had higher number density. The results imply that even a few γ′ precipitates can introduce a composite strengthening effect with the β′ precipitates. Meanwhile, the composite β′ and γ′ precipitates effectively strengthened the grain interior and hindered the twining during the tensile tests. Finally, the alloy containing the composite precipitates exhibited yield strength (YS) of 288 MPa and ultimate tensile strength (UTS) of 403 MPa which were only 232 MPa and 296 MPa, respectively, in the alloy containing only β′ precipitates.

The effects of different manganese (Mn) content of 0–0.8 wt% on the microstructures and room-temperature tensile properties of Mg-15Gd-1Zn (wt%) alloys have been investigated. The results reveal that the solution-treated microstructures of the alloys are mainly composed of α-Mg matrix, the secondary eutectic phase [(Mg, Zn) 3 Gd], X phase with 14H long period stacking ordered (LPSO) structure. However, small α-Mn particles precipitate within the α-Mg matrix with the increase of Mn content from 0 to 0.8 wt% during the solution treatment at 773 K. It shows that the α-Mn particles can inhibit grain growth, which can result in grain refinement. Moreover, Mn addition can promote the formation of 14H-LPSO structure in the solution-treated alloy by increasing stacking fault probability of α-Mg matrix. In this study, the influence mechanisms of Mn addition were suggested according to observation of microstructure and calculation of stacking fault probability. Besides, the room-temperature tensile properties can be improved as Mn addition content increases. In conclusion, the solution-treated Mg-15Gd-1Zn-0.8Mn (wt%) alloy exhibits an ultimate tensile strength of 275 MPa, a yield strength of 154 MPa and an elongation of 7.4%.

We proposed a nanoscale water switch composed of CNTs. A capped CNT with potassium ions in it may move under an external electric field, just like a piston. We can control the switch toggle between the open and closed states only by changing the direction of the external electric field. Molecular dynamics (MD) was used to simulate the performance of the switch. The results show that this device may act well as a switch. The response speed of the switch reaches the nanosecond level. The stability of the piston position is also investigated.

The effects of Zr and Mn additions to Mg-15Gd-1Zn alloy on the formation of long period stacking ordered (LPSO) structure under solution-treated (T4-treated) condition and the dynamic recrystallization (DRX) behavior alloy during extrusion have been investigated. The underneath mechanisms have also been proposed. The results indicate that Zr hinders the formation of LPSO structure by consuming Zn, while the Mn promotes it. On the other hand, Zr suppresses the grain growth by introducing Mg(Zn, Zr) precipitates during the DRX, while Mn effectively hinders the recrystallization process due to increasing LPSO structure. As the LPSO structure has dissolved in recrystallized grains, Mn addition affects little on suppressing grain growth in the grain growth step. Zr addition improves the mechanical properties of both the casting and extruded Mg-15Gd-1Zn alloys by refining grains and introducing Mg(Zn, Zr) precipitates. By contrast, the Mn addition is beneficial for the tensile properties of casting Mg-15Gd-1Zn alloy because of the LPSO structure with high ductility but harmful for the properties of the extruded alloys due to the coarse un-recrystallized grains.

A new process so-called air-cooled stirring rod (ACSR) was developed to prepare semisolid slurries of Al-8Si alloy. A simplified rheological high pressure die-casting (Rheo-HPDC) process was developed by combining the ACSR device with a HPDC machine to form wireless base station shells. Microstructures of slurries at different rotation speeds and air flows prepared by ACSR device were studied. Microstructures, mechanical properties and thermal conductivities of the shells formed by Rheo-HPDC were studied and compared with those produced by HPDC. The results indicate the ACSR device can prepare slurries in which primary particles are fine, spherical and uniformly distributed in the matrix. As rotation speed or air flow increases, the size of primary particles (α1-Al) decreases and shape factor increases. Rheo-HPDC parts show improved properties to those formed by HPDC, and increasing rates of ultimate tensile strength, yield strength, elongation, hardness and thermal conductivity are 15.4%, 8.2%, 62.1%, 6.67% and 2.1%, respectively.

The addition of Ag to the age hardenable Mg–Gd–Zr alloy system dramatically enhances early stage age hardening kinetics. Using atom probe tomography (APT), Ag-rich clusters were detected in a Ag-containing Mg–Gd–Zr alloy immediately after solution treatment and water quenching. During subsequent isothermal ageing at 200 °C, a high density of basal precipitates was observed during the early stages of ageing. These basal precipitates were enriched with Ag and Gd, as confirmed by APT. It is posited that Ag-rich clusters in the context of quenched-in vacancies can attract Gd atoms, increasing diffusion kinetics to facilitate the formation of the Ag + Gd-rich basal precipitates. The rapid formation of Ag + Gd-rich precipitates was responsible for accelerated ageing.

The behavior of graphene bombarded by fullerene (C60 and C70) and its derivatives through using non-equilibrium molecular dynamics method are studied. The microscopic mechanism of passing through graphene is obviously related to the initial structure of destroying carbon-carbon bonds and the strong interaction between the circular region of graphene and the cluster. The probability of passing through graphene depends on the incident velocity of clusters, the species of clusters, the temperature of heat baths, and the defect of graphene. Our results can provide a perspective for further understanding the mechanism of generating nanopores in graphene. The clusters used here may also bring about some potential utilities in the functionalization of graphene and the production of nanopores.

As-cast Mg–Nd–Zn–Zr (NZK) plates were subjected to friction stir processing (FSP) at a variety of tool rotation rates as well as traverse speeds, while the plunge depth remained constant. Thermocouples were placed systematically within each sheet to obtain the thermal history and temperature distribution during friction stir processing of NZK alloy. The relationship among processing parameters, heat input, microstructure and resulting mechanical properties were investigated to get a better understanding of the microstructure evolution during friction stir processing of NZK alloys. Cross sectional thermal distribution contour was built based on experimental data. The thermal field was then used to describe the effect of revolutionary pitch on materials flow (mainly focusing on onion rings), texture evolution, and grain structures. The results suggest that the center of onion rings generally locates in the intersection between the processing centerline and the 520 °C peak temperature isothermal line. Transition zone of texture exists between the shoulder driven zone and pin driven zone. The samples can be divided into two groups according to the way the grain structure varies with revolutionary pitch. In addition, the detected mechanical properties also demonstrate the effect of different pitches. Keywords: Friction stir processing, Mg–Nd–Zn–Zr alloy, Revolutionary pitch, Thermal field, Texture

We have investigated the thermal conductivity of C 60 and its derivatives caged with rare gas by using the nonequilibrium molecular dynamics method. It is reported that embedding C 60 with different rare gas atoms has a significant impact on its thermal conductivity. We analyze the phenomenon through the phonon spectra of rare gas atom and the C–C bonds length of C 60 . When the number of atoms inside the C 60 increases, the phonon spectra band width of rare gas expands and the length of C–C bonds becomes longer, which contributes to the depression of the thermal conductivity of C 60 . The method is applied to control the thermal conductivity of C 60 chains, which maybe a kind of potential materials in thermal circuits. Our results also provide a controllable method for the thermal management in nanoscale materials.

Three Mg–Y(–Gd)–Ag–Zr alloys with an iso-concentration of total alloying elements but different Y/Gd atomic ratios were hot extruded at 350 °C and their microstructures and mechanical properties were comparatively studied. Extruded Mg–2.4Y–0.4Ag–0.1Zr (at.%) base alloy shows a bimodal-grained structure composed of fine equiaxed recrystallised grains and coarse elongated unrecrystallised grains and has a 01 1 ¯ 0 //ED (extrusion direction) texture. In contrast, when Y is partially replaced with Gd, extruded Mg–1.6Y–0.8Gd–0.4Ag–0.1Zr (at.%) and Mg–0.8Y–1.6Gd–0.4Ag–0.1Zr (at.%) alloys with the Y/Gd atomic ratio of 2 and 0.5, respectively, exhibit a near fully recrystallised structure and have a [0001]//ED texture. While basal γ″ precipitates dominate but few β′ precipitates form in Mg–2.4Y–0.4Ag–0.1Zr alloy, a large number density of both β′ and γ″ precipitates form in Mg–1.6Y–0.8Gd–0.4Ag–0.1Zr and Mg–0.8Y–1.6Gd–0.4Ag–0.1Zr alloys after post-extrusion ageing. Precipitation in the Gd-containing alloys is considerably enhanced by partial substituting Y with Gd. The peak-aged Mg–1.6Y–0.8Gd–0.4Ag–0.1Zr alloy keeps a relatively good balance between grain boundary strengthening, dispersion strengthening and precipitation hardening and thus obtains a good combination of strength and ductility, whose room temperature tensile yield strength, ultimate tensile strength and elongation are 377 MPa, 479 MPa and 8.0%, respectively.

In order to match the solid food oxidation during logistics and storage process under severe high temperature, a double-switch temperature-sensitive controlled release antioxidant film embedded with lyophilized nanoliposomes encapsulating rosemary essential oils (REOs) was prepared. The double switch temperature at 35.26 and 56.98 &deg, C was achieved by development of a temperature sensitive polyurethane (TSPU) film. With biaxially oriented polyethylene terephthalate (BOPET) as a barrier layer, the intelligent complex film was prepared via coating the TSPU embedded with lyophilized nanoliposomes encapsulating REOs on BOPET. The results indicate that the REO is well encapsulated in nanoliposomes with encapsulation efficiency (EE) of 67.3%, high stability and lasting antioxidant effect during 60 days. The incorporation of lyophilized nanoliposomes containing REOs into TSPU remains the double-switch temperature-sensitive characteristic of the prepared TSPU. In agreement with porosity and WVTR results, the diffusion coefficient (D) of the antioxidant complex film sharply increases respectively at two switching temperatures, indicating that the intelligent double-switch temperature-sensitive controlled release property is functioning. Furthermore, compared with films directly added with REO, the lower Ds of films added with lyophilized nanoliposomes encapsulating REOs provides a longer-lasting antioxidant activity. Thus, the acquired controlled release antioxidant film sensitive to temperature at 39.56 and 56.00 &deg, C can be potentially applied for protection of solid food during distribution and storage process under severe high temperatures.

We study a binary mixture of polar chiral (counterclockwise or clockwise) active particles in a two-dimensional box with periodic boundary conditions. Beside the excluded volume interactions between particles, particles are also subject to the polar velocity alignment. From the extensive Brownian dynamics simulations, it is found that the particle configuration (mixing or demixing) is determined by the competition between the chirality difference and the polar velocity alignment. When the chirality difference competes with the polar velocity alignment, the clockwise particles aggregate in one cluster and the counterclockwise particles aggregate in the other cluster, thus particles are demixed and can be separated. However, when the chirality difference or the polar velocity alignment is dominated, particles are mixed. Our findings could be used for the experimental pursuit of the separation of binary mixtures of chiral active particles., Comment: 11 pages, 9 figures

A facile and green approach has been developed for synthesis of boron nitride quantum dots (BNQDs). The obtained BNQDs exhibit strong fluorescence and excellent stabilities, including high thermostability, good salt tolerance stability, pH-independence ability, and excellent antiphotobleaching capability. The strong inner filter effect between 2,4,6-trinitrophenol (TNP) and BNQDs resulted in fluorescence quenching of BNQDs. Thus, TNP can be selectively and sensitively detected in the concentration range of 0.25–200 μM, with a limit detection of 0.14 μM. The BNQD-based turn-off sensor shows potential prospects for rapidly and selectively detecting TNP in natural water samples without tedious sample pretreatment processes.

The microstructure and mechanical properties of the high-purity magnesium (99.99wt.% Mg) extruded by single direct extrusion experiment were investigated. For the extrusion speed of 0.2mm/s, the microstructure of extruded Mg rods was composed of equiaxed fine dynamical recrystallized (DRXed) grains and some elongated coarse un-DRXed grains. The yield strength (YS) and the elongation of the extruded bars were 105.3MPa and 46.7% respectively. In the case of extrusion speed of 4.0mm/s, the DRXed grains were remarkably coarsened and the elongated coarse un-DRXed grains vanished, meanwhile lots of twins occurred and the intensity of basal-plane texture increased a little. With the extrusion speed being raised from 0.2mm/s to 4.0mm/s, the YS and the elongation decreased to 60.5MPa and 22.1% respectively, but the ultimate tensile strength (UTS) was improved from 154.7MPa to 178.8MPa.

Using non-equilibrium molecular dynamics, we study the particle transport in graphene membrane nanopores. The dependences of collective diffusion coefficient on the shape, the length, the cross sectional area of nanopore and the environmental temperature are discussed. Compared with carbon nanotubes, multi-layers graphene membrane has much lower collective diffusion coefficient. It is suggested that the interfacial and intracrystalline resistance can suppress particles transport in nanopores. Our research provides valuable advice for controlling the particle transport through nanoscale channels.

It was based on laboratory test, in order to study on the high temperature stability, water stability and low-temperature crack resistance of AC-16 reclaiming asphalt mixture with different proportion of old material, this test takes into account 9 kinds of these asphalt mixture. The results show, with the old material blending ratio increased, the high temperature stability of asphalt mixture changed for the better, water stability and low-temperature crack resistance deteriorated. The pavement performance meet the requirements of secondary road or less, when old material content is within 70%. The research results provide reference for the application of reclaiming asphalt mixture.

Skin Stapler is an alternative instrument, which makes surgy easily and quickly and owns fine-looking effect without scars after the wound healed, to traditional surgical suture for the wound skin sewing. Magnesium recently is considered to develop medical implants because of its beneficial biocompatibility and bioabsorability. Due its less mechanical strength than traditional 316L stainless steel used in common staple, this paper try to optimize the structure of pure magnesium skin staple by FEM models and simulation as so to assure its biomechanical safty. Using ADINA software, two staples with different pre-bended shoulders and the traditional staple without shoulder are modeling to analyze its stress and plastical strain during structural deformation under load. The results, not only of pure magnesium models but also of 316L stainless steel models, showed that the shoulders optimization on staple structure has important role in its mechanical performance. The research increases the possibility of bioabsorable magnesium material application on medical skin staple.

Aragonite CaCO 3 with complicated morphologies needle-like structrues have been successfully synthesized through dolomite as raw materials by the decomposition of urea. The phase of the aragonite whiskers were characterized by X-ray diffraction and Fourier transform infrared, the structrue of the samples was characterized by scanning electron microscope and the effects of different ratio of materials were studied. The result show that the concentration of urea was found to have an effect on the morphology of aragonite crystals. All the prepared crystals were almost aragonite and there was no phase under varied experiment conditions.