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Industrial alumina was used as raw material in the high-temperature calcination process, and AlF 3 was introduced to promote mass transfer in the gas phase. The calcination environment, such as sealing, calcination temperature, and holding time, was analyzed to enhance the effect of AlF 3 to promote the crystal growth of alumina. Here, round-like flake α-Al 2 O 3 with an average particle size (D50) of about 18–38 μm were obtained at low dosages (0.1–0.4 wt%) of AlF 3. The morphology and particle size of α-Al 2 O 3 were further adjusted by introducing different types of micron-scaled nuclei as template inducers. Round-like flake and spherical-like large single crystals α-Al 2 O 3 with an average particle size greater than 35 μm were obtained, respectively, with 65 wt% of 15 μm flake and 10 μm bulk α-Al 2 O 3 nuclei added. In addition, the regulation mechanism of AlF 3 and nuclei on alumina crystal growth was also discussed. Finally, a theoretical basis and technical support for preparing high-performance, low-cost, and high thermal conductivity alumina fillers was provided. [Display omitted] [ABSTRACT FROM AUTHOR]

With photoconductor being transferred and separated, interface contact plays a crucial role in developing composites photocatalyst. In the present work, 2D crystalline g-C 3 N 4 (called as CCN) with 2D TiO 2 nanosheets (called as TO) obtained in situ oxidized single-layered Ti 3 C 2 T x MXene is designed by an electrostatic self-assembly technology. This CCN/TO nanosheets system with a few TiO 2 nanosheets distributed to the surface is not only prolonging lifetime of photoelectron but also stimulating photogenerated carriers transferred in contact interface. The electron transfer mechanism of CCN/TO is further proved by Pt photo-deposition method. Therein, the optimal CCN-TO-0.6 exhibits excellent performance of H 2 generation compared with single photocatalyst of CCN. The result shows that the crystalline g-C 3 N 4 photocatalysts introduced TiO 2 with interfacial effect favorably reduce H+ to H 2 and enhance photocatalytic activity. • The photocatalytic composites were synthesized by electrostatic self-assembly. • The 2D TiO 2 was obtained by in situ oxidized ultrathin Ti 3 C 2 T x MXene. • The composite role in light-excited carrier transfer and separation is described. • The effect of compound ratio of photocatalytic H 2 production was discovered. • The sample of 1:0.01 composite ratio showed the best photocatalytic activity. [ABSTRACT FROM AUTHOR]

In present work, a novel Co-free (CrFeNi 2) 100- x Y x (x = 0, 3, 6, 9) medium entropy alloys (MEAs) were successfully prepared by vacuum arc-melting method. The results revealed that the addition of rare-earth element Y had a great effect on the phase composition of CrFeNi 2 MEA, which was transformed from the single FCC phase structure to the duplex structure of the FCC and HCP (YNi 5 type) phases. Meanwhile, the phase evolution of the current alloy system was evaluated using the previous criteria (ΔH mix - δ , Ω - δ , Δ χ , VEC and Λ). In addition, the volume fraction of the HCP phase increased significantly with the increasing Y content, which caused the obvious grain refinement. On the other hand, the nanoindentation test results revealed that the nanohardness of the HCP phase (∼10.7 GPa) was more than three times of the FCC phase (∼3.4 GPa). The dislocation nucleation types of the FCC phase (3.68 GPa) and the HCP phase (6.46 GPa) were discussed by calculating their maximum initial plastic shear stress. With the increasing Y content, both the hardness and strength of the alloy were significantly improved, but the plasticity deteriorated. The second phase strengthening played a dominant role in the strength improvement of (CrFeNi 2) 100- x Y x MEAs, while both the solid solution strengthening and grain boundary strengthening contributed slightly to the strength increment. • The expensive Co elements were replaced with atoms by the lower-cost Ni element to reduce costs. • Phase precipitation behavior and mechanical properties of (CrFeNi 2) 100- x Y x (x = 0,3,6,9) MEAs were investigated for the first time. • The differences in mechanical properties and deformation behavior of FCC and HCP phases were explored. • The yield strength and hardness of (CrFeNi 2) 100- x Y x (x = 9) MEAs were increased to 1265 MPa and 485HV, respectively. [ABSTRACT FROM AUTHOR]

Mechanical milling was used to prepare nanocrystalline AZ31 magnesium (Mg) alloy with titanium (Ti) addition. During milling, the crystallite size of the AZ31 Mg matrix decreased steadily with the increase of milling time. After milling for 110 h, the crystallite size of the Mg phase of the alloy with 18 wt.% and 27 wt.% Ti additions was refined to 86 nm and 66 nm respectively, leading to the formation of a nanocrystalline Mg matrix microstructure. Meanwhile, the size of Ti particles added in the alloy also decreased gradually with the increase of milling time, and the Ti dispersions presented a positive effect on the refinement of the Mg matrix grains. By milling for 110 h, the average size of Ti particles was refined to less than 1 μm in the AZ31 Mg alloy with 18 wt.% Ti addition. After mechanical milling, the as-milled powders were cold pressed into green compacts, and the mechanical properties were characterized by Vickers' hardness and uni-axial compressive tests. It was found that the micro-hardness of mechanically milled AZ31 Mg alloy with 27 wt.% Ti addition reached about 147 Hv, which was almost three times larger than that of the as-received AZ31 Mg alloy. Meanwhile, the yield strength of mechanically milled Ti-added AZ31 Mg alloy was seen to be as high as 293 MPa at room temperature and 60 MPa at 300 °C, respectively. [ABSTRACT FROM AUTHOR]

In order to improve the efficiency and reduce the labor cost of cafeterias, an intelligent master–slave collaborative robot system is developed for cafeteria service in this paper. The developed system can automatically complete the tasks of scooping dishes, taking bowls and pouring dishes into the bowl based on master–slave collaboration. Specifically, a dynamic geometry feature graph convolution network (DGG) is devised using the 3D point cloud of the dish, which can efficiently predict the scooping positions of the different dishes. Moreover, a master–slave motion planning control method is proposed to achieve fast and smooth trajectories for both arms, which can accomplish the cafeteria service tasks collaboratively. Furthermore, we establish a dataset containing point clouds and color images of various Chinese food. Experiments demonstrate that the DGG network can achieve superior performance over other state-of-the-art point cloud segmentation networks. Besides, the designed robot system can well meet the requirements of operation accuracy and speed, confirming its practicality in cafeteria services. • An intelligent master–slave collaborative robot system is developed for cafeteria service. • A novel point cloud segmentation network DGG is devised to predict the scooping positions of different dishes. • Using the master–slave motion planning, the proposed system can realize efficient and close coordination. [ABSTRACT FROM AUTHOR]

The method of mechanical milling was applied to synthesize nanocrystalline Mg x Ti 100 − x ( x = 95, 90, 85) composite powders. The results reveal that mechanical milling is an effective method for preparing Mg–Ti composite powders, which consist of nanocrystalline Mg matrix and fine dispersed Ti particles. Moreover, the microstructure evolution and morphology of the as-milled powders were observed, and the corresponding mechanisms were also discussed. After milling for 60 h, the crystallite size of the matrix Mg in Mg x Ti 100 − x ( x = 95, 90, 85) composite powders was refined to 105 nm, 84 nm, and 76 nm, respectively. Meanwhile, the average size of the dispersed Ti particles in Mg x Ti 100 − x ( x = 90) composite powders was refined to about 1 μm. Based on the XRD data, the solid solubility of Ti in Mg was calculated by using the Vegard's law. For all these Mg–Ti composite powders, the solid solubility of Ti in Mg seemed to be closely related with the milling time and the content of Ti. In the 60 h-milled Mg x Ti 100 − x ( x = 95, 90, 85) composite powders, the solid solubility of Ti in Mg was estimated to be 0.56 at.%, 1.32 at.% and 2.35 at.%, respectively. [ABSTRACT FROM AUTHOR]

• Floating aluminum powder coated with SiO 2 was prepared using tetraethyl orthosilicate (TEOS) as raw material by sol-gel method. • The composite coating was prepared using modified Al powder and antistatic carbonaceous fiber (CF) as filler, EPDM as binder. • The composite coating that we prepared has low infrared emissivity compatible with high radar wave transmittance. Low infrared emissivity coatings have been widely used in many fields. At present, there are few researches on coatings that are compatible with low infrared emissivity and high radar wave transmittance. In this paper, floating aluminum (Al) powder coated with SiO 2 was prepared using tetraethyl orthosilicate (TEOS) as raw material by sol-gel method. The composite coating was prepared using modified Al powder and antistatic carbonaceous fiber (CF) as filler, EPDM as binder. The surface morphology, infrared absorption properties of the modified Al powder and the infrared emissivity, surface resistivity, electromagnetic properties and mechanical properties of the composite coating were analyzed. The results show that with the increase of TEOS addition amount, more SiO 2 was covered to the surface of floating Al powder. By adjusting the thickness of the surface modification layer of floating Al powder, the dielectric constant (ε) and dielectric loss tangent values (tanδ) of the composite coating were significantly reduced. When the addition amount of TEOS is 1 g for Al@SiO 2 , the ε and tanδ can be significantly reduced, and the infrared emissivity was less than 0.6, the tensile strength (σ b) and elongation rate at break (e) decreased slightly. This suggests that the composite coating has low infrared emissivity compatible with high radar wave transmittance was obtained, which is expected to be applied to the surface of aircraft radome. [ABSTRACT FROM AUTHOR]

Abstract: It is found that Al(III) can further enhance the intensity of resonance light scattering (RLS) of the silver nanoparticles (AgNPs) and nucleic acids system. Based on this, a novel method of determination of nucleic acids is proposed in this paper. Under optimum conditions, there are linear relationships between the enhancing extent of RLS and the concentration of nucleic acids in the range of 1.0×10−9–1.0×10−7 gmL−1, 1.0×10−7–2.0×10−6 gmL−1 for fish sperm DNA (fsDNA), 1.0×10−9–7.0×10−8 gmL−1 for calf thymus DNA (ctDNA) and 1.0×10−9–1.0×10−7 gmL−1 for yeast RNA (yRNA). The detection limits (S/N=3) of fsDNA, ctDNA and yRNA are 4.1×10−10 gmL−1, 4.0×10−10 gmL−1 and 4.5×10−10 gmL−1, respectively. The studies indicate that the RLS enhancement effect should be ascribed to the formation of AgNPs–Al(III)–DNA aggregations through electrostatic attraction and adsorption bridging action of Al(III). And the sensitivity and stability of the AgNPs–fsDNA system could be enhanced by Al(III). [Copyright &y& Elsevier]

• Coatings with both infrared stealth and electrostatic dissipation properties. • Effects of doping ratio of AZO, pigment content on properties were discussed. • Confirming the synergy effect of AZO and CF in difunctional coatings. The functional coatings play a critical role in many fields. To obtain difunctional composite coatings with low infrared emissivity and electrostatic dissipation (ESD) property, the composite coatings reinforced by aluminum-doped zinc oxide (AZO) and ESD carbonaceous fiber (CF) hybrid pigments were prepared, which were characterized by X-ray diffraction, scanning electron microscopy, infrared emissometer and insulation resistance tester. The effects of Al doping ratio of AZO, pigment adding amount and pigment type on the infrared emissivity and surface resistivity of the composite coating have been studied. The results confirmed that AZO of 7at.% doping concentration has lower infrared emissivity, and the infrared emissivity of AZO and CF coatings decreases with the increase of filler content. When AZO and CF are mixed at 1:1, the surface resistivity of the coating is 6380 Ω, which is much lower than that of any single pigment coating. Their synergy effect was contributed to form a continuous conductive path in the coating, enhance the tunnel current and obtain low surface resistivity for electrostatic dissipation. This work provides a new strategy for developing difunctional composite coatings with low infrared emissivity and electrostatic dissipation property. [ABSTRACT FROM AUTHOR]

The hot deformation behavior of a nickel-based superalloy was investigated by means of isothermal compression tests in the strain rate range of 0.001–10 s −1 at 1110 °C. Transmission electron microscope (TEM) and electron backscatter diffraction (EBSD) technique were used to study the effect of strain rate on the microstructure evolution of the alloy during hot deformation. The results revealed that the dynamic recrystallization (DRX) process was stimulated at high strain rates ( ε ̇ ⩾ 5 s - 1 ) due to the high dislocation density and adiabatic temperature rise. Meanwhile, high nucleation of DRX and low grain growth led to the fine DRX grains. In the strain rate rage of 0.001–1 s −1 , the volume fraction of DRX grains increased with the decreasing strain rate, and the grain growth gradually governed the DRX process. Moreover, the strain rate has an important effect on DDRX and CDRX during hot deformation. On the other hand, particular attention was also paid to the evolution of twin boundaries during hot deformation. It was found that there was a lower fraction of Σ 3 boundaries at the intermediate strain rate of 1 s −1 , while the fractions of Σ 3 boundaries were much higher at both the lower strain rates ( ε ̇ ⩽ 0.1 s - 1 ) and higher strain rates ( ε ̇ ⩾ 5 s - 1 ). [ABSTRACT FROM AUTHOR]

Aluminum doped zinc oxide (AZO) nanoparticles with different doping concentrations were prepared by a simple one-step hydrothermal synthesis method. The crystal structure, morphology, infrared absorption, infrared emission and microwave loss properties of the AZO nanoparticles were analyzed in detail. With the increase of the aluminum doping concentration, the crystal plane spacing does not change much, while the grain size increases gradually, and the thickness of the flakes and the average size of the particles have no significant change. With the increase of the Al doping concentration, the infrared emissivity of AZO tends to decrease first and then increase, among which the AZO infrared emissivity with Zn-ion ratio of 95:5 is the lowest. The electromagnetic parameters of AZO with a mole doping ratio of 93:7 were carried out at a frequency range of 2–18 GHz, the real part (ε′) and imaginary part (ε″) of the complex permittivity varies between 4.3-4.5 and 0.2–0.4, respectively, the dielectric loss tangent (tan δ) varies between 0.04 and 0.09. [ABSTRACT FROM AUTHOR]

Two kinds of Fe/C nanofibers were prepared by electrospinning and calcination under the same process conditions. A simple way was used to adjust the size of the Fe nanoparticles by using different spinning solvents. The one was prepared by a mixture of water and anhydrous alcohol as solvents (named as CNF water) and the other by N,N-Dimethylformamide and anhydrous alcohol (named as CNF DMF). Due to the higher solubility to iron salts and larger surface tension of water, CNF water gained a larger size of Fe nanoparticles and average diameter. In addition, the graphite layers wrapped on Fe nanoparticles which were formed during calcination were thinner in CNF water than CNF DMF. These factors endowed CNF water better microwave absorption performance. The results of XRD, SEM, HRTEM, Raman, magnetostatic and electromagnetic properties analysis revealed the influence mechanisms of solvents on the formation, microstructure and properties of Fe/C nanofibers. [ABSTRACT FROM AUTHOR]

The mechanism underlying the crowding effects that assist the condensation process by multivalent cations under confinement is not yet reported. Based on the strong correlation model, Monte Carlo simulation was implemented to detect the crowding effects on DNA condensation within a capsule-like space, and its geometry controlled by the aspect ratio. With the addition of crowders, the condensed conformations confined within the spherical space (aspect ratio is 1) become more compact than those without crowders. The DNA-condensed conformations undergo a transition from the initial random coil structure to toroid structure, followed by the extended rod-like structure, and finally to totally compacted structure. The critical volume fraction corresponding to the transition from the rod-like structure to totally compacted structure pertained to the crowder size proportionally. Moreover, the critical volume fraction corresponding to the phase transition strongly depends on the confinement geometry, the critical volume fraction for the case with constant radius is inversely proportional to the aspect ratio. Conversely, the case with constant cylinder length showed that the critical volume fraction is proportional to the aspect ratio. These phenomena are consistent with their corresponding phase diagram re-expressed in the space of volume fraction and aspect ratio. The effects of confinement geometry and crowder size on the response of DNA condensation to crowding are elucidated and generalized into the space diagram in the space of aspect ratio and crowder size. When the aspect ratio less than 1.6 and the crowder size larger than 2.0 nm or when the aspect ratio ≥ 1.6 and the crowder size larger than the critical d c ∗ , the DNA conformation undergo the transition from the initial random coil structure to toroid structure, followed by totally compacted structure; when the aspect ratio ≥ 1.6 and the crowder size ≤ d c ∗ , the DNA condensed conformations will be condensed further from the totally compacted structure to the extended rod-like structure. Furthermore, the transition from the totally compacted structure to the extended rod-like structure is entirely due to the crowder size and the confinement geometry between the de Gennes and Odijk regimes. [ABSTRACT FROM AUTHOR]

• Propose a privacy-preservation signaling game for edge-based IoT networks. • Obtain optimal privacy preservation strategies from theoretical and practical views. • Address the problem of obtaining the convergent game equilibrium in practice. • Have a lower computational complexity available to real-life implementation. Data privacy leakage can be severe when a malicious Internet of Things (IoT) node sends requests to gather private data from an edge-computing-based IoT cloud storage system across the edge nodes. To solve this problem, a privacy-preservation signaling game for edge-computing-based IoT networks is proposed to characterize the interactions between an IoT node and its corresponding edge node when managing an IoT resource-grant system. Optimal privacy preservation strategies for edge nodes are then theoretically derived. A signaling Q-learning algorithm is then designed to address the problem of achieving convergent equilibrium and game parameters from a practical perspective. The theoretical results are validated using simulations that focus on two statistical points (i.e., the optimal probability of an IoT node requesting maliciously and the posterior probability of an IoT node being malicious). By comparing the proposed signaling Q-learning algorithm with the greedy algorithm benchmark, the proposed algorithm is shown to more effectively decrease the optimal probability of an IoT node sending malicious requests. Thus, privacy preservation for edge-computing-based IoT cloud storage systems can be strengthened. [ABSTRACT FROM AUTHOR]

Nanocrystalline Ti/AZ61 magnesium matrix composite, prepared by mechanical milling, was annealed in the temperature range of 573–723 K for various durations. During annealing treatment, diffusion of Al and Ti elements, formation of precipitates and grain growth behavior were observed and the evolution of hardness was obtained. Based on microstructural evolution, the mechanism for the precipitating of Ti and Al from magnesium matrix was analyzed. And the corresponding schematic illustration of microstructural evolution model was proposed. By the observation from high-resolution transmission electron microscopy, it was found that dispersing nanometer sized particulates, precipitated from Ti and Al supersaturated Mg solid solution, pined up magnesium grain boundaries. During annealing treatment, the nano-scaled precipitates together with original submicron Ti particulates hindered the movement of grain boundaries. Thus, the thermal stability for magnesium grains was improved. After annealing treatment at 723 K for 600 min, this magnesium matrix composite with the average grain size of ∼93 nm was still nanocrystalline. In addition, influence of temperature and time on hardness was investigated. After annealing treatment at 723 K for 600 min, the hardness of annealed Ti/AZ61 composite is approximately 116 HV, presenting outstanding thermal stability. [ABSTRACT FROM AUTHOR]

The paper presents a systematical simulation study of the influence of gradient doping of both emitter and back surface field layer on the photovoltaic (PV) performances of TCO/a-Si:H(p)/a-Si:H(i)/c-Si(n)/a-Si:H(n+)/TCO/Ag bifacial structure heterojunction with intrinsic thin layer (HIT) solar cells using AFORS-HET software simulation package. The gradient doping instead of uniform doping for emitter can promote the PV performance due to the presence of an additional electric field coming from the gradient doping, while the gradient doping of back surface field layer has negligible effect or negative influence on the cell performance compared to uniform doping, which can be explained by the varied energy band diagrams near the back junction interface. A final efficiency of 25.75% has been realized by using gradient doping of emitter with the same total doping amount as that of uniform doping case and uniform doping of back surface field layer for n-type bifacial HIT solar cells. This study can offer guidance on how to improve HIT solar cell efficiency beyond the world record value in experiment and how to achieve higher efficiency in mass production of HIT solar cells. [ABSTRACT FROM AUTHOR]

AZ61 Mg and AZ61 Mg with 10 at. %Ti addition (AZ61-10 at. %Ti) were mechanically milled and a comparative study on microstructure evolution was performed. During mechanical milling, Mg grain refining/nanocrystallization and the dissolving of Mg 17 Al 12 precipitates, with the formation of Al supersaturated Mg solid solution, were observed for both materials due to mechanical milling. As analyzed by density dislocation, Ti dispersions hinder the movement of dislocations and grain boundaries and accelerate the dislocation pile-up. Therefore, Ti addition accelerated Mg grain refining, meanwhile, the ultimate Mg grain (43.47 nm) with Ti dispersions was smaller than that (69.19 nm) without Ti dispersions based on X-ray diffraction and transmission electron microscopy results. As the scanning electron microscope and X-ray diffraction exhibiting, the dissolving of Mg 17 Al 12 precipitates was expedited by Ti dispersions and the dissolving of Al in Ti phase was verified by high angle annular dark field. Moreover, during mechanical milling, Ti particulates entranced Mg particles gradually by the welding and cracking effect. After mechanical milling, Ti phase, dispersed in Mg matrix, were smashed to approximately 274.0 nm and Ti supersaturated Mg solid solution was synthesized with the solid solubility being 1.07 at. %. [ABSTRACT FROM AUTHOR]

Nanocrystalline AZ61 powders, dispersed with submicron/nanometer Ti particulates, were mechanically milled and a comparative study on thermal stability and mechanical properties was performed. After mechanical milling, Ti dispersions were cracked to submicron/nanometer particulates and Mg grains were refined to nanocrystalline. As illustrated by high-resolution transmission electron microscopy, coherent lattice and semi-coherent lattice interfaces between magnesium and titanium were achieved. Based on high angle annular dark field and corresponding energy dispersive spectrometer maps, Al dissolved into Ti particulates after mechanical milling. Moreover, the emergence of Ti 3 Al phase was verified by X-ray diffraction during mechanical milling and heat treatment. According to heat treatment results, this nanocrystalline magnesium composite exhibits a preeminent thermal stability among nano-structured magnesium alloys. After annealed at 673 K for 600 min, the composite still remained nanocrystalline with average grain size being 68.6 nm. Due to such microstructure, the composite revealed prominent mechanical property with the hardness being 146.6 HV. Simultaneously, the hardness of annealed composite remained high, with the value being 134.7 HV, which could ascribe to the excellent thermal stability. [ABSTRACT FROM AUTHOR]