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In this work, the authors studied the corrosion resistance of composite deposits of yttrium (III) oxide (Y2O3) and graphene on a nickel (Ni) coating. The corrosion resistance of the coating was significantly improved after the composite deposition, particularly for the nickel–graphene coating with the addition of 0.05 g/l graphene. The E corr and I corr of the coating were optimized to 404.340 mV and 0.24 × 10−8 A/cm2, respectively. The surface morphology, microstructure, passivation behavior and corrosion products of the coating were analyzed, and the mechanism of corrosion resistance enhancement was revealed. The results show that deposition of the yttrium (III) oxide and graphene composite can decrease the surface roughness of the coating. The graphene composite has a more significant effect and greatly reduces the contact area between the coating and the medium. Moreover, particle composite deposition can also lead to grain refinement. Graphene composite deposition reduces the grain size from 75.3 to 18.9 nm, significantly improving the nucleation and formation of the passivation film. Uniform deposition of graphene at grain boundaries can also hinder the infiltration of corrosive media into the interior region. Upon composite deposition, the improved corrosion resistance of magnets significantly increases their performance and service life, facilitating their railway applications.

Unmanned Aerial Vehicles (UAVs) are expected to play a key role in transportation systems to improve safety and reliability, particularly where data traffic is non-homogeneous and non-stationary. However, heterogeneous data sharing and processing poses numerous security and privacy concerns, which may prevent UAVs from being an integral part of future Intelligent Transportation Systems (ITS) networks. Some of the well-known security and privacy issues in the UAV-enabled ITS ecosystem include tracking UAVs and vehicle locations, unauthorized access to data and message modification. Therefore, in this paper, we contribute to the sum of knowledge by combining the Hyperelliptic Curve Cryptography (HECC) techniques, digital signature and hash function to present a privacy-preserving authentication scheme. The security features of the proposed scheme are assessed using formal security analysis methods i.e., Real-Or- Random (ROR) oracle model. To examine the performance of the proposed scheme, a comparison with other existing schemes has been carried out. The results reveal that the proposed scheme outperforms its counterpart schemes in terms of computation and communication costs.

Post-sinter annealing process plays an important role in the microstructures and magnetic properties of the Nd-Fe-B sintered magnets. In this paper, systematically investigated are the magnetic properties and microstructures of the as-sintered and post-sinter annealed Nd-Fe-B magnets with Pr-Fe-Ga boundary addition. Two choice consecutive annealing methods are adopted at high and low temperatures, namely the 1st annealing at 880 oC for 2 h and then the 2nd annealing at 440 oC for 3 h. It is exceptional to find out that both the remanence and coercivity are improved after 2nd annealing process for this type of magnet. The coercivity is hugely increased from 10.09 kOe for the as-sintered sample to 17.19 kOe for the 2nd annealed magnet, with a significant increment of 70.37% in coercivity. The extraordinary magnetic properties of Br=14.44 kGs, Hcj=17.19 kOe and (BH)max=51.08 MGOe are obtained for the designated Nd-Fe-B sintered magnets without heavy rare earth (HRE) elements manufactured by dual alloy method. The Curie temperature is monotonically decreased from 634 K to 602 K while the c-axis alignment degree is optimized after annealing. Microstructural observation and analysis indicate that the elemental distribution patterns are altered after the 2nd annealing. The diffusion of the aggregate (Pr,Nd,Cu,Ga)-rich phase from triple junctions into the grain boundary regions is ascribed to the formation of thin and continuous grain boundary layer, which is critical to improve the microstructures and magnetic properties.

SmCo5 magnets were prepared by spark plasma sintering (SPS) technique. The phase constitutions, magnetic properties, and microstructures of magnets prepared under different sintering temperatures were investigated systematically. It is observed that the 1:5 phase and 2:7 phase coexist in the magnet, and 2:17 phase appears when the temperature rises to 1050 °C. The best magnetic properties were obtained for the magnets prepared at 1000 °C, with remanence Jr = 0.45 T, intrinsic coercivity Hcj = 985 kA/m, and maximum energy density (BH)max = 37 kJ/m3. It is shown that the SPSed magnet prepared at 1000 °C exhibits excellent thermal stability which is described in terms of temperature coefficient of remanence (α) = −0.15%/°C and temperature coefficient of coercivity (β) = −0.25%/°C in the temperature range of 27–400 °C. The microstructure analysis showed that the high density of the magnet and the uniform distribution of the hard magnetic phase are the main reasons for the excellent magnetic properties.

NdFeB hot-pressed and hot-deformed magnets were prepared by hot-pressed (HP) sintering and spark plasma sintering (SPS). The effects of sintering mechanisms of SPS and HP on the microstructure of hot deformation magnets were studied. The temperature of the mold surface is much higher than that of the sample in the cavity in HP, but lower than that of the sample in SPS. The Nd-rich phase is uniformly distributed and the grain size is smaller in the hot-deformed magnets prepared by HP, while the Nd-rich phase is excessively enriched and the grain size in the liquid-enriched region is abnormal in the hot-deformed magnets prepared by SPS. The comprehensive magnetic properties of hot deformed magnets prepared by SPS are significantly lower than those prepared by HP.

The magnetic properties, magnetocaloric effect and magnetoresistance in ErNi single crystal have been investigated in detail. With decreasing temperature, ErNi single crystal undergoes two successive magnetic transitions: a paramagnetic to ferromagnetic transition at TC =11 K and a spin-reorientation transition at TSR = 5 K. Meanwhile, a sharp field-induced metamagnetic transition is observed below the TC along the a axis. ErNi single crystal possesses a giant magnetocaloric effect around TC. The maximum magnetic entropy change is -36.1 J (kg K)−1 along the a axis under the field change of 0−50 kOe. In particular, the rotating magnetocaloric effect in ErNi single crystal reaches its maximum under a relatively low field, and the maximum rotating entropy change with a value of 9.3 J (kg K)−1 is obtained by rotating the applied field from the [011] to [100] directions under 13 kOe. These results suggest that ErNi could be a promising candidate for magnetic refrigeration working at liquid-helium temperature region. Moreover, a complicated transport behavior is uncovered in ErNi single crystal, which is attributed to the complex magnetic states and magnetic polaronic effect. Both positive and negative magnetoresistance are observed. A considerable large magnetoresistance with the value of -34.5 % is acquired at 8 K under 50 kOe when the field is along the [100] direction.

Cerium doped zinc oxide/carbon nanotubes (Ce doped ZnO/CNTs) composites are synthesized using sol-gel, hydrothermal deposition and one-pot hydrothermal methods. These composites are tested for photocatalytic hydrogen evolution from water-methanol mixture to check the effect of synthesis method on photocatalytic activity of these composites. Each synthesis method induces unique physiochemical properties in composite and hydrogen evolution rates. The composite prepared by one-pot hydrothermal method shows highest hydrogen evolution of 759 μmolh−1g−1 under sunlight. This hydrogen evolution rate is significantly higher than the sol-gel synthesized photocatalyst (579 μmolh−1g−1) and hydrothermal deposition method (621 μmolh−1g−1). The high hydrogen evolution activity of the prepared composites can be attributed to small crystallite size, low recombination of charge carriers, large active surface area, short diffusion pathway for photoinduced electrons and high oxidation potential of photogenerated holes. Focused on different methods, this study provides a pathway for production of efficient semiconductor photocatalysts for environmental applications.

In this study, the liquid phase plasma (LPP) was irradiated over pure zinc oxide (ZnO), strontium (Sn) doped ZnO, and Sn doped ZnO/CNTs photocatalysts for hydrogen evolution from pure water and from aqueous solution of water-methanol. The possible relationship between hydrogen evolution and optical emissions from LPP for activation of ZnO based photocatalysts was revealed. The role of carbon nanotubes (CNTs) as a support material for improved photocatalytic hydrogen evolution was also investigated in this study. The photocatalytic hydrogen evolution from water mixed methanol under LPP irradiation was compared with pure water splitting. The photolysis produced negligible amount of hydrogen due to minimal photodecomposition of water molecules under LPP irradiation. The plasma born reactive species also played crucial role in photolysis. However, the hydrogen evolution rate increased significantly in the presence of ZnO photocatalyst. Further improvement in hydrogen evolution rate was noticed on Sn doping of ZnO and compositing with CNTs. The highest hydrogen evolution rate of 11.46 mmh−1g−1 from water mixed methanol was achieved with Sn doped ZnO/CNTs photocatalyst. This hydrogen evolution rate from water-methanol solution was 9 times higher than from the splitting of pure water. This hydrogen evolution rate is attributed to excessive production of hydroxyl radicals, red shift in optical band gap of Sn doped ZnO/CNTs photocatalyst, slow electron-hole recombination and fast decomposition of methanol as sacrificial reagent.

In order to obtain high magnetic properties in Ce–Pr–Nd–Fe–B spark plasma sintered (SPSed) magnets, the alloys were introduced by the dual-alloy method. The relationship of microstructure, magnetic properties, and thermal stability was investigated. The remanent magnetization, coercivity, and maximum energy product were sharply enhanced from 0.68 T, 653 kA/m, and 75.62 kJ/m3 to 0.80 T, 865 kA/m, and 104 kJ/m3 for the magnets that with 0 and 75 wt.% Pr–Fe–B addition. The Curie temperature also increased from 542 K to 563 K after adding Pr–Fe–B alloys. The scanning electron microscopy (SEM) analysis showed that, during the sintering process, the rare-earth elements migrated into the flake boundary and diffused in 2:14:1 main phases; thus, (Ce, Pr, Nd)2Fe14B hard magnetic phases were formed, which is helpful to optimize the microstructure and magnetic properties. An enhancement of exchange coupling among the grains of SPSed magnets was obtained as a result of grain refinement by adding Pr–Fe–B alloys.

Internet of Drones (IoD) is a decentralized networking architecture that makes use of the internet for uniting drones to enter controlled airspace in a coordinated manner. On the one hand, this new clan of interconnected drones has ushered in a new era of real-world applications; Small drones, on the other hand, are generally not designed with security in mind, making them exposed to fundamental security and privacy concerns. Limited computing capabilities, along with communication over an open wireless channel, exacerbate these challenges, making the IoD unfeasible for secure operations. In this article, we propose an identity-based proxy signcryption scheme to address these issues. During data transfer between drones and to the cloud server, the proposed scheme supports outsourcing decryption and member revocation. The proposed scheme is based on the notion of Hyper Elliptic Curve Cryptography (HECC), which improves network computation efficiency. We use formal security analysis with the Random Oracle Model (ROM) to evaluate security toughness. The performance analysis of the proposed scheme has also been reviewed in terms of computation and communication costs with the relevant existing schemes. The results obtained from both the security and performance analyses affirm the superiority of the proposed scheme.

Nowadays, searching for the materials with multiple magneto-functional properties and good mechanical properties is vital in various fields, such as solid-state refrigeration, magnetic actuators, magnetic sensors and intelligent/smart devices. In this work, the magnetic-field-induced metamagnetic reverse martensitic transformation (MFIRMT) from paramagnetic martensite to ferromagnetic austenite with multiple magneto-responsive effects is realized in Fe-doped Co-V-Ga Heusler alloys by manipulating the magnetic ordering. The martensitic transformation temperature Tm reduces quasi-linearly with increasing Fe-content. In strikingly contrast with the Fe-free alloys, the magnetization difference (ΔM') across martensitic transformation increases by three orders of magnitude for Fe-doped alloys. The increased ΔM' should be ascribed to the reduction of Tm, almost unchanged Curie temperature of austenite and the increased magnetic moment in the samples with higher Fe-content. The large ΔM' provides strong driving force to realize the MFIRMT and accordingly multiple magneto-responsive effects, such as magnetocaloric, magnetoresistance and magnetostriction effects. Meanwhile, giant Vickers hardness of 518 HV and compressive strength of 1423 MPa are achieved. Multiple magneto-responsive effects with exceptional mechanical properties make these alloys great potential candidates for applications in many fields.

Recently it is a hot topic to make full use of high abundant Y element in Nd2Fe14B-type permanent magnets. In contrast to Pr and Nd elements, Y shows different metallurgical behaviors during preparation process. In this paper, we have explored the magnetic properties, microstructures and corrosion performance of Pr-Nd-Y-Fe-B magnets fabricated by spark plasma sintering (SPS) technique from the ribbons of nanocrystalline and amorphous precursors, respectively. The coercivity and maximum energy product were improved for the magnets prepared from amorphous precursor materials (denoted as SPS-A hereafter) compared with the magnets prepared from crystalline precursor materials (denoted as SPS-C hereafter). Magnetic properties of Jr = 0.79 T, Hci = 864 kA/m, and (BH)max = 102 kJ/m3 were obtained for SPS-A magnets. In contrast with SPS-C magnets, the magnetic properties of SPS-A magnets are not so sensitive to the preparation conditions, which is quite beneficial to the homogeneity of microstructure and enhancement of coercivity for large-scale production of the designated magnets. Aggregated (Pr,Nd,Y)-rich phase was found out in SPS-C magnets. Pr and Nd elements are rich at grain boundary while Y is distributed uniformly at main phase and grain boundary phase. The strip grains and equiaxed grains exist in SPS-C and SPS-A magnets, respectively. The enhanced magnetic properties for SPS-A magnets are accredited to the uniform distribution of rare-earth-rich phase and low demagnetization factor. It is revealed by electrochemical test and dipping test that the corrosion potential is more positive and the corrosion rate is slower for the SPS-A magnets in 3.5 wt.% NaCl solution. The work is also expected to shed light on developing the nanocrystalline Pr-Nd-Y-Fe-B SPSed high-performance magnets in industry.