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BackgroundAlthough numerous studies had revealed associations between autoimmune diseases (AIDs) and thyroid cancer (TC), the potential causal associations between the two remain poorly defined.MethodsUsing five approaches, two-sample Mendelian randomization (MR) analyses were carried out to determine the causal effects of 12 major AIDs on risk of TC. The sensitivity analyses were conducted to verify the reliability of the analysis. The reverse MR analysis was performed to evaluate the possibility of reverse causation.ResultsThe results showed a significant causal association of systemic lupus erythematosus (SLE) and primary biliary cirrhosis (PBC) on the risk of TC. Genetically predicted PBC elevated the risk of TC (OR = 1.46, 95% CI = 1.06-2.02, p = 0.021). The risk of TC was also increased by genetically predicted SLE (OR = 6.52, 95% CI = 1.38-30.84, p = 0.018) with heterogeneity. After outlier-corrected analyses, the results still suggested that genetically predicted SLE increased the risk of TC (p = 0.019). No evidence of a causal relationship between the remaining 10 AIDs and TC was observed. No reverse causal effects of TC on AIDs were found in reverse MR analysis.ConclusionThese findings support a significant causal association of SLE/PBC on the increased risk of TC, indicating that patients with SLE/PBC should be under a close monitoring of TC.

The fast proliferation of edge devices for the Internet of Things (IoT) has led to massive volumes of data explosion. The generated data is collected and shared using edge-based IoT structures at a considerably high frequency. Thus, the data-sharing privacy exposure issue is increasingly intimidating when IoT devices make malicious requests for filching sensitive information from a cloud storage system through edge nodes. To address the identified issue, we present evolutionary privacy preservation learning strategies for an edge computing-based IoT data sharing scheme. In particular, we introduce evolutionary game theory and construct a payoff matrix to symbolize intercommunication between IoT devices and edge nodes, where IoT devices and edge nodes are two parties of the game. IoT devices may make malicious requests to achieve their goals of stealing privacy. Accordingly, edge nodes should deny malicious IoT device requests to prevent IoT data from being disclosed. They dynamically adjust their own strategies according to the opponent's strategy and finally maximize the payoffs. Built upon a developed application framework to illustrate the concrete data sharing architecture, a novel algorithm is proposed that can derive the optimal evolutionary learning strategy. Furthermore, we numerically simulate evolutionarily stable strategies, and the final results experimentally verify the correctness of the IoT data sharing privacy preservation scheme. Therefore, the proposed model can effectively defeat malicious invasion and protect sensitive information from leaking when IoT data is shared.

This paper proposes a cooperative non-orthogonal multiple access (NOMA) based two-way transmission scheme for a two-user cellular system, in which a base station (BS) exchanges information with a directlink user and an indirect link user. With superimposition coding, physical-layer network coding (PLNC) and successive interference cancellation, the BS and the two users are able to exchange messages within three time slots. We derive the sum-rate upper bound of the proposed scheme and investigate the optimal time and power allocations to maximize the sum-rate bound. Numerical results demonstrate that the derived bound is tight and the proposed scheme can improve the sum-rates significantly as compared with existing NOMA-based schemes.

Garnet-type Li7La3Zr2O12 (LLZO) is one of the most promising solid-state electrolytes (SSEs). However, the application of LLZO is limited by structural instability, low ionic conductivity, and poor lithium stability. To obtain a garnet-type solid electrolyte with a stable structure and high ionic conductivity, a series of TaCe co-doping cubic Li6·4La3Zr1.4-xTa0.6CexO12 (LLZTCO, x = 0, 0.02, 0.04, 0.06, 0.08, 0.10, 0.20, 0.30) electrolytes were successfully synthesized through conventional solid-phase method. The Ta5+ doping can introduce more lithium vacancies and effectively maintain the stability of the cubic phase. The Ce4+ with a larger ionic radius is introduced into the lattice to widen the Li+ migration bottleneck size, which significantly increased the ionic conductivity to 1.05 × 10−3 S/cm. It also shows excellent stability to lithium metal by the optimization of Li+ transport channel. Li||LLZTCO||Li symmetric cells can cycle stably for more than 6 000 h at a current density of 0.1 mA/cm2 without any surface modifications. The commercialization potential of LLZTCO samples in all solid-state lithium batteries (ASSLBs) is confirmed by the prepared LiFePO4||LLZTCO||Li cells with a capacity retention rate of 98% after 100 cycles at 0.5C. This new co-doping method presents a practical solution for the realization of high-performance ASSLBs.

In this paper, the microstructure evolution and thermal stability of nanocrystalline (NC) AZ31-2.5 wt%VP magnesium matrix composites were studied, while the hardness was analyzed. The results showed that the NC AZ31-2.5 wt%VP still kept NC scale after annealing at 300 °C and 350 °C. Even at 400 °C and 450 °C, the grain size of the annealed composite only grew to 113 nm and 132 nm, which was still in ultrafine grain scale, illustrating excellent thermal stability of NC AZ31-2.5 wt%VP. Furthermore, the V particles, which was uniformly distributed in the Mg matrix, had no obvious change in dimension after annealing, while it also had no new phase formed. The stabilization mechanism was expounded and found that the pinning effect of V particles effectively inhibited the grain growth of Mg matrix at high temperature. In addition, the grain growth kinetics equation (D6−D06=kt) was utilized to explain the grain growth behavior of NC AZ31-2.5 wt%VP, and the activation energy (Ea) of grain growth was calculated to be 130.9 kJ/mol, which was much higher than that of pure Mg (92 kJ/mol). Eventually, the hardness of NC AZ31-2.5 wt%VP was contrastive studied and the hardness evolution curves at different temperatures were obtained. After annealing treatment was performed at 450 °C for 180min, the hardness remained at 80 HV, which was higher than that of as-cast AZ31 (53 HV).

In this paper, the pavement maintenance and rehabilitation practices are presented based on the analysis of as-built data housed in PaveM—the pavement management system for the California Department of Transportation (Caltrans). A 35-year period of as-built data from 1983 to 2017 was analyzed, involving 37 treatment strategies with 17 for asphalt and 20 for Portland Cement Concrete (PCC) pavements. The top ten treatment strategies, geographical and temporal variation of treated mileage, together with treatment costs and corresponding network condition were presented. It was found that: (1) The top 10 strategies are, in descending order: “Chip Seal”, “Hot Mix Asphalt (HMA) Thin Overlay”, “HMA Medium Overlay”, “HMA Thick Overlay”, “Mill and Fill”, “Grind/Replace Slabs”, “Slab Replacement”, “Crack Seat and Overlay”, “HMA Lane Replacement”, and “PCC Lane Replacement”. The top 10 strategies accounted for about 84% of the total treated lane kilometers. (2) On average, about 12.4% of the total network inventory (both asphalt and concrete pavements) was treated each year. This is equivalent to treat the entire network once every eight years. (3) About 18.3% of AC and 35.1% of PCC rehabilitation mileage was found applied on a lane-by-lane basis, instead of across all lanes. This finding solidified the necessity of a lane-based pavement management system in California. (4) The average annual weighted maintenance and rehabilitation cost per lane kilometer is about $192,248 for asphalt and $366,804 for PCC pavements. Due to the lack of preventive types of treatments for PCC pavement, the per lane kilometer cost is almost twice as high as that for its asphalt counterpart. It is suggested that more preventive type of treatments be implemented for PCC pavements.

The influence of induction heating on the grain boundary character distribution (GBCD) in near-surface regions of a cold-rolled Nickel-based superalloy was researched. After induction heating, most of low-Σ coincidence site lattice (CSL) boundaries were Σ3 boundaries, which were mainly formed via the growth accident model. Moreover, the grain structures evolution during induction heating had a great influence on the evolution of GBCD. At the low strain of 0.1, both the fraction of Σ3 boundaries and grain size increased with the increasing temperatures, while the former was closely related to the better development of grain-clusters at the higher temperature. In addition, the coherent Σ3 boundaries were easier to be formed at the higher temperature during induction heating, owing to their low interface energy and mobility. At the large strain of 0.5, the fraction of Σ3 boundaries also increased with the increasing temperatures, but the grain size exhibited the opposite trend, which was closely related to the well development of static recrystallization (SRX) behaviors. Meanwhile, there was a “symbiotic relationship” between the SRX grains and Σ3 boundaries during induction heating. Through the electrochemical corrosion tests, it was proved that induction heating can contribute to the improvement of corrosion properties of superalloys via increasing the fraction of Σ3 boundaries, while the best corrosion resistance appeared in the samples treated at 800 °C with the strain of 0.5. Moreover, the evolution of both Σ9 and Σ27 boundaries was also closely related to strains and induction heating temperatures, but their fractions were less than 4%.

In this study, a novel fine-grained AZ31 magnesium (Mg) alloy reinforced with sub-micron vanadium particles (VP) was prepared by powder metallurgy (P/M). It was found that VP could accelerate the pile-up of dislocations and the refinement of Mg crystallite sizes during the milling process. The Mg matrix was refined to nanocrystalline scale after milling for 90 h, and the ultimate average crystallite size was only 25 nm. Meanwhile, a homogeneous distribution of the sub-micron VP in Mg matrix was achieved. After hot-extrusion process, the average grain size of Mg matrix was 3.08 μm, which reached fine-grained scale. Additionally, the AZ31-2.5 wt % VP composite exhibited competitive mechanical properties. Compared to the as-cast AZ31 Mg alloy, the microhardness, yield strength, ultimate tensile strength and elongation of AZ31-2.5 wt % VP composite increased by 102%, 128%, 59% and 10%, respectively. The grain boundary strengthening played a dominant role in improvement of strength. Simultaneously, the strengthening mechanisms of thermal mismatch, Orowan strengthening and load transfer also made a contribution. Besides that, the fracture mechanism of the AZ31-2.5 wt % VP composite included ductile and brittle fracture mode.

The evolution of grain boundary character distribution in a cold-deformed nickel-based superalloy during the electropulsing treatment (EPT) was studied. The results revealed that both coherent Σ3 boundaries (Σ3c) and incoherent Σ3 boundaries (Σ3ic) were formed in the recrystallized structures mainly by growth accidents during EPT, while the fraction of Σ3ic boundaries became much lower at the higher EPT temperatures. Meanwhile, the fraction of Σ3 boundaries increased with the increasing EPT temperatures till 850 °C, and decreased again at 900 °C. In addition, the high mobility of grain boundary during EPT could promote the formation of stacking errors at some locations of high angle grain boundaries (HAGBs), and thus promoting the nucleation of annealing twins. With the increasing EPT time, the fraction of Σ3 boundaries increased slightly, and the unstable Σ3ic boundaries were transformed into stable Σ3c boundaries, in which intersecting migrating SRX fronts were easier to be extended. On the other hand, a lot of low-Σ CSL grain boundaries were formed in the pre-deformed alloy with the strain of 0.1 during EPT, which was mainly attributed to the development of large grain-clusters. As the strain was large enough, the energy supplied by electropulsing could enable the cold-rolled alloy to effectively utilize the stored energy on the formation of Σ3 boundaries. Besides that, the evolution of Σ9 and Σ27 boundaries was analyzed in detail as well as the corrosion resistance of the studied alloy after different treatments.

Heterogeneous and mobile wireless sensor networks (HMWSNs) are generally practical in constructing smart Internet of Things. However, malware can easily propagate itself over HMWSNs and make harm such as data interception and unauthorized activities. To defend such malware, developing a model to disclose dynamics of malware propagation becomes urgently required. In this context, a heterogeneous and mobile vulnerable-compromised-quarantined-patched-scrapped (VCQPS) model is proposed by considering both the heterogeneity and mobility of HMSNs (heterogeneous and mobile sensor nodes). Then, differential equations of transition proportions among all states are achieved by analyzing the changeable quantities of HMSNs belonging to different states. Further, the existence of the stationary points of the VCQPS model is proved, upon which the malware propagation threshold is derived by calculating the reproduction number. The stability of the malware-free stationary-point is also proved. Experiments are performed to validate the stability of the malware-free stationary-point and show the effectiveness of the VCQPS model by comparing our model with traditional SIS and SIR models.

In this paper, selective laser melting (SLM) was used to manufacture corrax stainless steel samples under different parameters. It was found that the SLMed samples were mainly composed by lots of fine martensite (including cellular structure, cellular dendritic grains and blocky grains), and trace austenite. During SLM forming process, a large number of low-angle grain boundaries (LAGBs) and high-density dislocations were formed in the matrix. Meanwhile, the samples showed weak texture and no obvious preference orientation. Moreover, the relative density of all SLMed samples reached above 90%, and the relative density was above 97% when the laser energy density was 54.13–78.19 J·mm−3. Under the optimal process parameters of P = 190 W, V = 1.1 m·s−1, the relative density of sample reached above 99.52 ± 0.09%, while the sample exhibited the best mechanical properties, including the highest microhardness (374.2 ± 6.5HV), yield strength (YS = 946 ± 7.3 MPa), ultimate tensile strength (UTS = 1084 ± 3 MPa) and elongation (EL = 17.64 ± 0.18%). Moreover, the strengthening mechanisms of SLMed samples mainly included grain boundary strengthening, dislocation strengthening and precipitation strengthening, while dislocation strengthening played a dominant role. Besides that, the fracture mechanisms of SLMed samples belonged to ductile fracture, except for the samples prepared with laser energy density below 54.13 J·mm−3.

Traditional methods for solving the inverse kinematics of a hyper-redundant manipulator (HRM) can only plan the path of the end-effector with a complicated solving process, where obstacle avoidance is also not considered. To solve the above problems, a novel method for solving inverse kinematics of HRM is proposed in this paper: the variable dimension scaling method (VDSM), which can solve complex inverse kinematics while avoiding obstacles. Through this method, the path of the end-effector is scaled under a certain proportion and is adjusted depending on the position of the obstacle, which has good universality. The number of link angles changed is as small as possible in the process of achieving the end-effector moving along the desired path. With the redundancy of HRM, obstacle avoidance can be implemented in any environment by the proposed method. Through simulation and experiments in different environments, the above advantages of VDSM are verified.

Heterogeneous wireless sensor networks (WSNs) are widely deployed, owing to their good capabilities in terms of network stability, dependability, and survivability. However, they are prone to the spread of malware because of the limited computational capabilities of sensor nodes. To suppress the spread of malware, a malware spread model is urgently required to discover the rules of malware spread. In this paper, a heterogeneous susceptible-iNsidious-infectious-recovered-dysfunctional (SNIRD) model was proposed, which not only considers the communication connectivity of heterogeneous sensor nodes but also reflects the characteristics of malware hiding and dysfunctional sensor nodes. Then, the fraction evolution equations of heterogeneous sensor nodes in different states in discrete time were obtained. Furthermore, the existence of equilibria for the heterogeneous SNIRD model was proved, and the malware spread threshold was obtained, which indicates whether malware will spread or fade out. Finally, the heterogeneous SNIRD model was simulated and it was contrasted with the conventional SIS and SIR models to validate its effectiveness. The results construct a theoretical guideline for administrators to suppress the spread of malware in heterogeneous WSNs.

This work is aimed at studying the foaming behavior of pure ultra-high molecular weight polyethylene (UHMWPE) with supercritical carbon dioxide (scCO2). The effects of foaming temperature and saturation pressure on the final foam structure were investigated by using two different one-step batch foaming processes. An in-situ high-pressure observing system was used to record the crystal change of UHMWPE film during heating and cooling stages with/without pressurized CO2. The results showed that the cell size and the cell density were affected by the combined effects of crystal, temperature, and pressure. Experimental results with different foaming temperatures showed that higher foaming temperatures led to larger cells and lower cell densities. In the processes of foaming during the heating stage (Proc1) and cooling stage (Proc2), the expansion ratio increased first and then decreased with the increase of temperature. Before obtaining the maximum expansion ratio, compare with Proc2, the cell size and expansion ratio of foams were smaller, and the cell density was higher in Proc1. Experimental results with different saturation pressures showed that higher pressure led to lower cell density and larger average cell diameter in Proc1 due to the reduction of crystals and melt strength. While in Proc2, higher saturation pressure led to higher cell density due to the increase of solubility of CO2, and the cell density decreased as the pressure further increased due to cell coalescence.

Summary: Carbon materials are widely used in lithium-ion batteries (LIBs) due to their high performance, safety, and reliability, along with low cost and easy availability. However, the low lithium storage capability of bare carbon materials limits the further improvement of the capacity of LIBs. Here, we report a facile self-poring strategy for the synthesis of trace amounts of ZnO quantum dots (QDs) (∼5 nm) embedded in highly porous carbon nanosheets by using the metal centers of a Zn-based metal-organic ligand structure as a pore-creating agent. Benefiting from the synergistic functions of nanostructuring, heterocomponent doping, and QDs effects, the as-prepared materials deliver superior lithium storage properties in comparison with the existing carbon-based materials—2,300 mAh g−1 at 0.2 A g−1, ∼600 mAh g−1 at 10 A g−1, and ∼700 mAh g−1 after 3,000 cycles at 5 A g−1—and are promising candidates for next-generation high-capacity LIB electrodes.

In this work, vanadium particles (VP) were utilized as a novel reinforcement of AZ31 magnesium (Mg) alloy. The nanocrystalline (NC) AZ31–VP composites were prepared via mechanical milling (MM) and vacuum hot-press sintering. During the milling process, the presence of VP contributed to the cold welding and fracture mechanism, resulting in the acceleration of the milling process. Additionally, increasing the VP content accelerated the grain refinement of the matrix during the milling process. After milling for 90 h, the average grain size of AZ31-X wt % Vp (X = 5, 7.5, 10) was refined to only about 23 nm, 19 nm and 16 nm, respectively. In the meantime, VP was refined to sub-micron scale and distributed uniformly in the matrix, exhibiting excellent interfacial bonding with the matrix. After the sintering process, the average grain size of AZ31-X wt % VP (X = 5, 7.5, 10) composites still remained at the NC scale, which was mainly caused by the pinning effect of VP. Besides that, the porosity of the sintered composites was no more than 7.8%, indicating a good densification effect. As a result, there was little difference between the theoretical and real density. Compared to as-cast AZ31 Mg alloy, the microhardness of sintered AZ31-X wt % VP (X = 5, 7.5, 10) composites increased by 65%, 87% and 96%, respectively, owing to the strengthening mechanisms of grain refinement strengthening, Orowan strengthening and load-bearing effects.

The influence of electropulsing treatment (EPT) parameters on the static recrystallization (SRX) microstructure in a cold-deformed Ni-based superalloy was investigated. During EPT, both the volume fraction of SRX grains and the average grain size increased with the increasing EPT temperature, which was attributed to the thermal effect and athermal effect induced by EPT. The mobility of SRX grain boundaries was promoted at the higher temperature due to the thermal effect, while the nucleation rate would be increased by EPT through decreasing the thermodynamic barrier. The formation of parallel dislocations caused by electron wind force could also play an indirect role in promoting SRX process. Moreover, the volume fraction of SRX grains increased significantly with the extension of EPT time at 700 °C, while the EPT time had a trivial effect on the average grain size. In addition, the sufficient deformation was essential to the occurrence of SRX behavior during EPT, and the localized Joule heating effect could promote the SRX behavior in the samples with the larger strains. Besides that, the influence of twining and carbides on the SRX behaviors was also investigated.

In this work, nanocrystalline AZ31 magnesium alloy powders, reinforced by submicron TiB2 particles, were prepared via mechanical milling. It was found that TiB2 particles stimulated the fracture and welding of AZ31/TiB2 powders, leading to the acceleration of the milling process. Meanwhile, the TiB2 particles were refined to submicron-scale size during the milling process, and their distribution was uniform in the Mg matrix. In addition, the matrix was significantly refined during the milling process, which was also accelerated by the TiB2 particles. The formation of grain boundary segregation layers also led to the weakened TiB2 peaks in the XRD patterns during the mechanical milling. The grain sizes of AZ31–2.5 wt % TiB2, AZ31–5 wt % TiB2 and AZ31–10 wt % TiB2 powders were refined to 53 nm, 37 nm and 23 nm, respectively, after milling for 110 h. Under the combined effect of the nanocrystalline matrix and the well-dispersed submicron TiB2 particles, the AZ31/TiB2 composites exhibited excellent micro-hardness. For the AZ31–10 wt % TiB2 composite, the micro-hardness was enhanced to 153 HV0.5.

The California Department of Transportation (Caltrans) has been using scrap tire rubber in asphalt pavements since the 1970s in chip seals and the 1980s in rubberized hot mix asphalt(RHMA). Both the wet (field blend) and dry processes were used in early trials. Caltrans has also used rubber modified binders containing both crumb rubber modifier and polymer modifier that could be manufactured at a refinery facility, a terminal blend wet process. Since the beginning of this century, Caltrans increased the use of scrap tire rubber in paving projects and invested considerable resources in developing technically sound, cost effective, and environmentally friendly strategies for using scrap tire rubber in roadway applications. By the end of year 2010, approximately 31%of all hot mix asphalt (HMA) placed by Caltrans was rubberized HMA, roughly 1.2 million tons. Caltrans efforts in using asphalt rubber products were also demonstrated in its research and technology development. These included the construction of two full-scale field experiments, five warranty projects, and an accelerated pavement study using a heavy vehicle simulator. Additionally, terminal blend asphalt rubber and rubberized warm mix asphalts began to be experimented on trial basis. This paper provides a comprehensive review of Caltrans experience over four decades with asphalt rubber products. Current practices and future outlook are also discussed.