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Abstract The basal dislocations play a key role in the deformation of hexagonal Mg alloys. However, its core structure and mechanical behavior have thus far not yet been understood adequately, largely owing to the fact that the basal dislocation, often decorated with segregated solute atmosphere and dissociated into two partials, cannot be modeled accurately. Significant discrepancies exist between theoretically calculated and experimentally observed structures for these dissociated dislocations. Here we present a comprehensive theoretical scheme to model them in the Mg alloys with alloying elements of Y, Zn, Al and Li, respectively. Firstly, solute–dislocation interactions were computed by appropriate first-principles calculations. Secondly, the statistic solute concentration at a dislocation is estimated by a Fermi–Dirac distribution. Finally, all these effects on dislocations are integrated into an improved two-dimensional Peierls–Nabarro model to predict their core structures and mechanical behaviors in Mg alloys. It is shown that although Zn, Al and Li atoms have little effect on basal dislocations, Y atoms can largely increase their dissociated width. Furthermore, when it moves from its ground state configuration, the dissociated dislocation can further be widened, such that its dissociated widths in a Mg–0.8Y (at%) alloy at 300 K can reach 12–36 nm, in rather good agreement with the experimentally observed values of 20–30 nm. Besides, the Peierls and yield stresses of Mg alloys shall increase with increasing added solute concentration, while they are decreased drastically with increasing the temperature from 300 to 800 K, but with the Mg-Y alloy as somewhat exception, which is again consistent with experimental observations.

In the present work, the combination of shot peening (SP), low-temperature plasma nitriding (PN) and arc deposition (AD) is proposed to improve the wear performance of Ti6Al4V alloy. The low-temperature rapid nitriding of Ti6Al4V alloy was realized by SP pretreatment to obtain a desired nitrided interlayer. The high-density structural defects produced by SP pretreatment promote the nitriding kinetics at low temperature. The nitrided interlayer consists of an outermost TiN/Ti2N compound layer and an inner diffusion layer, showing a diffusion-typed hardness-profile, which is beneficial for the enhancing of adhesion strength and load-bearing capacity. Moreover, the improvement of adhesion strength is associated closely with TiN/Ti2N compounds which can provide heterogeneous nucleation sites for AD coating with a high hardness of about 3100 HV. The high bearing-load capacity and adhesion strength can ensure the excellent wear resistance of SP-PN-AD-coated sample when compared to single AD or PN-AD samples, especially under intensive wear load conditions. The present work provides a new insight into surface hardening of Ti alloys.

The key parameters of growth and nucleation of Al3TM particles (TM = Sc-Zn, Y-Cd and Hf-Hg) have been calculated using the combination of the first principles calculations with the quasi-harmonic approximation (QHA). Herein, the diffusion rate Ds of TM elements in Al is calculated using the diffusion activation energy Q, and the results show that the Ds of all impurity atoms increases logarithmically with the increase in temperature. With the increase in atomic number of TM, the Ds of 3–5d TM elements decreases linearly from Sc, Y and Hf to Mn, Ru and Ir, and then increases to Zn, Ag and Au, respectively. The interface energy γα/β, strain energy ΔEcs, chemical formation energy variation ΔGV and surface energy Esurave were further computed from the based interface and slab models, respectively. It was found that, with the increase in the atomic number of TM, the interface energies γα/β of Al/Al3TM (TM = (Sc-Zn, Y-Cd)) decreased from Sc and Y to Mn and Tc and then increased to Zn and Cd, respectively (except for the (001) plane of Al/Al3(Fe-Co), the (111) plane of Al/Al3Pd and the (110) and (111) planes of Al/Al3Cd). The strain energies ΔEcs of Al/Al3TM (TM = (Sc-Zn)) increased at first, and then decreased for all cycles. The chemical formation energy ΔGV of all Al3TM changed slightly in the temperature range of 0~1000 K, except that the ΔGV of Al3Sc, Al3Cu, Al3(Y-Zr), Al3Cd, Al3Hf and Al3Hg increased nonlinearly. With the increase in atomic number at both 300 and 600 K, the ΔGV of 3–5d TM elements increased from Sc, Y and Hf to Mn, Tc and Re at first, and then decreased to Co, Rh and Ir, respectively, and slightly changes at the end. With the increase in atomic number of TM, the variation trends of the surface energies of Al3TM intermetallic compounds present similar changes for all cycles, and the (111) surface always has the lowest values.

The stability and mechanical and thermodynamic properties of Al11RE3 intermetallics (RE = Sc, Y and lanthanide La-Lu) have been investigated by combining first-principles and Debye model calculations. It was found that the formation enthalpies of the Al11RE3 intermetallics are all negative, indicating that they are stable; moreover, the experimental values of Al11La3 and Al11Ce3 are in good agreement with the predicted values, which are −0.40 kJ/mol and −0.38 kJ/mol, respectively. The calculated results of the mechanical properties reveal that the Young’s modulus E and shear modulus G of Al11RE3 (RE = La, Ce, Pr, Nd and Sm) intermetallics are obviously greater than that of Al, implying that the stiffness, toughness, and tensile strength of them are significantly greater than those of aluminum, and that they, as strengthen phases, can effectively improve the mechanical property of aluminum alloys. The Poisson’s ratio v of Al11Sc3 (0.37) is the largest, and the heterogeneity is obvious. All the Al11RE3 intermetallics can enhance the thermostability of the aluminum because of their lower Gibbs free energy F in the range of −5.002~−4.137 eV/atom and thermal expansion coefficient α of Al in the range of 2.34~2.89 × 10−5/K at 300K, as well as higher entropy and constant volume-specific heat than aluminum at finite temperatures. With an increase in the atomic number, different change trends were observed for the formation enthalpy ΔHf, bulk modulus B, Young’s modulus E, and shear modulus G. This paper can provide ideas and help for designing a high-performance, heat-resistant aluminum alloy.

Graphene promises to revolutionize the plastic market, providing extra-properties to polymer composites. However, the commercialization process is seriously hindered by low-yield exfoliation and a large amount of waste liquid generated during fabrication process. Herein, we report total conversion from graphite to few-layer graphene nanocomposite with zero waste. Flake graphite is directly exfoliated by bead milling into few-defect, few-layer graphene with a yield of 100% in polymer monomers at an ultrahigh concentration of up to 4 wt% (≈ 40 mg/mL), followed by in situ bulk polymerization into few-layer graphene nanocomposite. The graphene nanosheets constitute a three-dimensional jammed network within the nanocomposite, and thus bring significant enhancement in modulus (2.6 times), electrical conductivity (12 orders of magnitude) and thermal conductivity (1 order of magnitude), as compared to pure polymer material. This strategy opens a promising avenue for low-cost, environmental-friendly fabrication of graphene-containing polymer nanocomposites with improved mechanical and functional properties.

The synthesis of diazonium salts is historically an important transformation extensively utilized in dye manufacture. However the highly reactive nature of the diazonium functionality has additionally led to the development of many new reactions including several carbon-carbon bond forming processes. It is therefore highly desirable to determine optimum conditions for the formation of diazonium compounds utilizing the latest processing tools such as flow chemistry to take advantage of the increased safety and continuous manufacturing capabilities. Herein we report a series of flow-based procedures to prepare diazonium salts for subsequent in-situ consumption.

At the probe limit, the effects of three typical nonlinear corrections of Born-Infeld electrodynamics (BINE), logarithmic Lagrangian (LNE) and exponential Lagrangian (ENE) on the holographic ferromagnetic model under the four-dimensional Gauss-Bonnet gravity background are studied by numerical calculation. For comparison, the Gauss-Bonnet parameter α is fixed in the article. In the absence of an external magnetic field, three different nonlinear electrodynamic corrections reduce the critical temperature respectively and make the spontaneous magnetic moment more difficult to form. In the case of opening the external magnetic field, the magnetic susceptibility density always satisfies the Curie-Weiss law, and the increase of the nonlinear parameters under the three corrections will prolong the period of the external magnetic field. Comparing the three corrections horizontally, the exponential form of nonlinear electrodynamics correction has a more significant effect on the parameters.

Introduction Increasing numbers of jurisdictions are legalising assisted dying (AD). Developing research protocols to study the experiences and outcomes of legislation is imperative. AD is a topic that, by nature of its complexity and inherent ethical issues, lends itself to qualitative research. Using the objectives of the statutory framework, this qualitative study aims to provide a robust review of the newly formed AD service in New Zealand and the extent to which it is safe, people-centred, dignity-enhancing, accessible and available equitably to all eligible people.Methods and analysis The research uses an appreciative inquiry design to focus on what is working well, what could be improved, what constitutes the ‘ideal’ and how to enable people to achieve that ideal. We are using online semi-structured interviews and face-to-face focus groups to explore the experiences of key stakeholders: eligible/ineligible service users; eligible/ineligible service users with impairments; families of service users; AD providers; non-providers (providers who object to AD and others who are not directly involved in providing AD but are not opposed in principle); health service leaders; and Māori community members. An estimated 110 participants will be interviewed. We will conduct thematic and regulatory analyses of data.Ethics and dissemination The ethical aspects of this study have been approved by the Northern A Health and Disability Ethics Committee through the full review pathway (2023 EXP 18493). To disseminate the findings, we will draft resources to support interviewee groups, to be developed with feedback from stakeholder meetings. We will submit evidence-based recommendations to inform the government review of the End of Life Choice Act 2019. Findings will be disseminated in peer-reviewed publications, conferences, webinars, media, stakeholder feedback sessions and accessible research briefings.

Heat transfer characteristics of buried closed-loop heat exchange tubes directly affect the efficiency of ground source heat pump systems. To improve the heat transfer efficiency of a geothermal system, a simulation model of a shallow buried closed-loop heat exchanger in Chengdu is established. The heat transfer characteristics of U-tube heat exchangers are investigated. The influence of tube diameter, flow velocity, tube configuration and well group distribution distance on the system heat transfer was studied. The results show that the highest heat transfer efficiency of the buried tube is at the bottom of the inlet section. The optimal heat transfer fluid velocity in the inlet is around 0.6 m/s, and the continuous operation time should not exceed 10 h. The efficiency of the W-shaped structure is increased by 4.8% than U-shaped, and the uniform distribution distance arrangement is the best. The overall heat transfer performance of the borehole heat exchanger is the highest when the distribution distance is 0.5-0.75 m. Those results can provide a basis for designing buried heat exchangers and optimizing geothermal systems. [ABSTRACT FROM AUTHOR]