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As nuclear fuel cladding, Zr alloys have need for a good corrosion resistance. For decades, several generations of Zr alloys with excellent corrosion resistance have been developed through adjusting content of Sn and Nb. However, the mechanism of Sn and Nb influencing the corrosion resistance is still not clear. Here, our computational simulations indicate, Sn or Nb can segregate at grain boundary (GB) of surface oxide film which results in variation of GB cohesion and influences the corrosion resistance. Using the first-principles method, we find that Sn segregation reduce GB cohesion and decrease oxide film protectiveness; In contrast, Nb segregation enhance GB cohesion and improve oxide film protectiveness. The results are well consistent with the previous experiments that reducing Sn or adding Nb can promote corrosion resistance of Zr alloys. These findings provide a basis for understanding the roles of alloying elements in the corrosion resistance of Zr alloys, which is useful to future design of new Zr alloys.

Reversible solid oxide fuel cell (rSOFC) can produce and store energy through dual-mode operating, which is promising for balancing the conflicts between power supply and requirements. One crucial issue is to develop high performance of fuel electrode materials, in terms of materials costs, mechanical strength, mass production in commercialization. The reversible performance of the materials may be enhanced by electrode microstructure optimization in the preparation procedures. It is beneficial to understand the mechanisms of sintering process, in terms of the electrode particle interactions and sintered structure in the molecular/nanoparticle level. Accordingly, a molecular dynamics method is developed to simulate the sintering process for the LST/GDC nanoparticle systems. It is found that a high sintering temperature is beneficial for increasing triple-phase-boundary (TPB) length, but not for the effective surface area of catalyst particles. A mass fraction of 0.5–0.6 is predicted as the optimal LST composition for the TPB length, active surface area, and compatible thermal expansion coefficient. The heat capacity and thermal conductivity increase in the high sintering temperature and high mass fraction of LST conditions. The methodology and findings can provide a guideline on optimization of the sintering conditions for LST/GDC electrodes, which may promote the commercialization of rSOFC technology.

Bifunctional electrocatalyst for efficiently catalyzing hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in pH-universal electrolyte is desirable for the industrial overall water splitting technology. In this work, we have synthesized Iridium nanorods (Ir-NR/C) by annealing Ir nanoparticles at 300 °C requiring comparatively low overpotentials of 290 mV, 296 mV and 305 mV to achieve current density of 10 mA cm−2 for OER catalysis in 0.5 M H2SO4, 1 M KOH and 1 M PBS with a low Ir loading of 14 μg cm−2, respectively, resulting in ∼30 times higher mass activity compared to commercial IrO2. Moreover, stable OER performance is recorded due to the formed thin amorphous Iridium oxides (IrOx) layer protecting the underneath metallic Ir from direct electrochemical dissolution and coalescences. Besides, IrOx layer negligibly affects the HER performance in acidic medium; but promotes the HER catalytic activities in alkaline and neutral electrolytes since the Volmer step (water dissociation) is efficiently catalyzed by IrOx layer enabling a 6-fold better mass activity than benchmarked Pt/C. Ir-NR/C performs superior stability during HER catalysis in a wide pH range ascribed the prevention of Ir migration and aggregation. Finally, the assembled water splitting device by Ir-NR/C shows robust activity and exceptional stability than benchmarked Pt/C-IrO2 in pH-universal electrolytes.

The anisotropy of metal oxidation is a fundamental issue, and the oxidation of Zr surfaces also attracts much attention due to the application of Zr alloys as cladding materials for nuclear fuels in nuclear power plants. In this study, we systematically investigate the diagram of O adsorption on low Miller index Zr surfaces by using first-principles calculations based on density functional theory calculations. We find that O adsorption on the basal surface, Zr(0001), is more favourable than that on the prism surfaces, Zr(112[combining macron]0) and Zr(101[combining macron]0), under strong O-reducing conditions, while O adsorption on the prism surface is more favourable than that of the basal surface under weak O-reducing conditions and the O-rich conditions. Our findings reveal that the anisotropy of adsorption properties of O on the Zr surfaces is dependent on the O chemical potential in the environment. Furthermore, the ability of the prism for O adsorption is stronger than that of the basal surface under the O-rich condition, which is consistent with the experimental observation that the oxidation of the prism Zr surface is easier than that of the basal surface. Systematic surveys show the adsorption ability of the surface under strong O-reducing conditions is determined by the low coordination numbers of surface atoms and surface geometrical structures, while the adsorption ability of the surface under weak O-reducing conditions and O-rich conditions is only determined by the low coordination number of surface atoms. These results can provide an atomic scale understanding of the initial oxidation of Zr surfaces, which inevitably affects the growth of protective passivation layers that play critical roles in the corrosion resistance of Zr cladding materials.

In this study, the gene encoding hemocyanin subunit L, LvHcL, was cloned from Litopenaeus vannamei and the genomic organization was characterized. This gene was diverse with many SNPs and also had at least four isoforms, while one of them (LvHcL4) only had two exons and the exon2 was missed. Transcription analysis showed that these isoforms of LvHcL were up-regulated after WSSV challenge in WSSV-resistant shrimp, while the transcriptions were decreased constantly in WSSV-susceptible shrimp. It is suggested that the hemocyanin had rich polymorphism and was involved in the antiviral response. These results could extend our previous findings and provide insights into the immune feature of hemocyanin, which would be helpful for further studies aimed at antiviral mechanism in invertebrate.

Understanding the sintering mechanism in porous anodes is necessary for developing durable anodes suitable for use in solid oxide fuel cells. A multi-nanoparticle sintering simulation method based on molecular dynamics (MD) calculation was developed for this purpose [J. Xu et al., J. Phys. Chem. C, 2013, 117, 9663–9672]. The method can be used to calculate the effect of the porous structure properties, such as the porosity and framework structure, on the sintering, unlike previous sintering simulations with conventional nanoparticle models. We revealed that, in a Ni/YSZ porous anode, the YSZ nanoparticle framework suppresses sintering of Ni nanoparticles by disrupting the growth of the neck between two Ni nanoparticles. In this paper, we used our method to reveal the effect of ceramic type on the sintering processes. We investigated the difference between the sintering and degradation processes in Ni/YSZ and Ni/ScSZ anodes. In the simulation, the degree of sintering of the Ni nanoparticles in Ni/ScSZ was smaller than that in Ni/YSZ. The stronger adhesion of Ni to ScSZ nanoparticles than to YSZ nanoparticles prevented the Ni nanoparticles from approaching each other in the Ni/ScSZ anode, inhibiting sintering. Our multi-nanoparticle sintering MD simulations revealed the different sintering processes for Ni nanoparticles in Ni/YSZ and Ni/ScSZ anodes. We also investigated the effect of sintering on degradation. The hydrogen adsorption sites and electrochemical reaction sites of the hydrogen oxidation decreased as the degree of sintering increased. A low degradation of the Ni/ScSZ anode relative to that of the Ni/YSZ anode was observed. Furthermore, we showed the effect of porosity on degradation induced by sintering in Ni/YSZ and Ni/ScSZ, and found an optimal porosity. These findings cannot be obtained by conventional two- or three-nanoparticle sintering MD simulations. Our multi-nanoparticle sintering simulation method is useful for revealing the types of ceramics suitable for inhibiting sintering and degradation in anodes, and can be used to design durable anodes.

Diamond-like carbon (DLC) coatings have attracted much attention as an excellent solid lubricant due to their low-friction properties. However, wear is still a problem for the durability of DLC coatings. Tensile stress on the surface of DLC coatings has an important effect on the wear behavior during friction. To improve the tribological properties of DLC coatings, we investigate the friction process and wear mechanism under various tensile stresses by using our tight-binding quantum chemical molecular dynamics method. We observe the formation of C-C bonds between two DLC substrates under high tensile stress during friction, leading to a high friction coefficient. Furthermore, under high tensile stress, C-C bond dissociation in the DLC substrates is observed during friction, indicating the atomic-level wear. These dissociations of C-C bonds are caused by the transfer of surface hydrogen atoms during friction. This work provides atomic-scale insights into the friction process and the wear mechanism of DLC coatings during friction under tensile stress.

In recent years, correlation filters have achieved excellent performance in terms of accuracy and robustness for visual target tracking. However, it is still a challenging task to improve the tracking capability which can handle complex background and deal with target scale changes. In this paper, a new tracker based on the correlation filter framework with scale adaptation for visual target tracking is presented: 1) an effective scale adaptive scheme, which can solve the fixed template size with the basis of traditional correlation filter tracker, is proposed; 2) two powerful features including histogram of oriented gradient and color name, which can improve the overall tracking performance, are integrated together; 3) a high-confidence model updating strategy, which can avoid the model occlusion problem during model updating, is developed. The extensive experimental evaluations on OTB-2013 dataset have demonstrated that the developed novel tracker in our study can successfully outperform the other trackers on the benchmark dataset with 51 sequences. It is very promising for various challenging scenarios.

The alpha subunit of Eukaryotic Initiation Factor 2 (eIF2α) is a key translation regulator that plays an important role in cellular stress responses, which including virus infection. To investigate whether WSSV infection can activate the PERK-eIF2α pathway, the eIF2α in shrimp Litopenaeus vannamei, designed as LveIF2α, was analyzed. The LveIF2α, a 332-amino acid polypeptide, shares a high degree of similarity with eIF2α from other species, having two eIF2α protein signatures at the 13-88 aa and 192-243 aa. The WSSV challenge experiment showed that the protein level of the total LveIF2α was decreased after infection, while the phosphorylation of LveIF2α has no significant change, which indicated that the phosphorylation ratio of LveIF2α was increased after infection. Furthermore, inhibitor treatment led to a significant decrease of WSSV loads. Moreover, the Binding immunoglobulin protein (BiP), an endoplasmic reticulum (ER) stress sensor, and PERK were also investigated during virus infection and it was shown that they were both up-regulated. Taken together, these results suggested that WSSV infection can induce ER stress and activated the unfolded protein response (UPR), and the PERK-eIF2α pathway is important for innate immune during WSSV infection in shrimp.

The corrosion behavior of the Ti&ndash, 6Al&ndash, 4V alloy was investigated in a sulfate-reducing bacteria (SRB) solution. The results showed that sulfate-reducing bacteria has good affinity with the surface of the Ti&ndash, 4V alloy after 5 days. A potentiodynamic polarization test demonstrated that the corrosion resistance of the Ti&ndash, 4V alloy was initially improved but deteriorated quickly in the subsequent period. The corrosion mechanism of the Ti&ndash, 4V alloy was revealed by analyzing its microstructure with the aid of scanning electron microscopy, X-ray photoelectron spectroscopy and X-ray fluorescence. The pitting corrosion was deemed to be a typical cause of the corrosion behavior of the alloy in the SRB solution. The underlying mechanism of the pitting corrosion was proposed for the alloy.

The Fe-based amorphous composite coatings with various content of Al2O3–13%TiO2 (AT13) additions (0–20 wt%) were prepared on 45 steel substrate by plasma spraying. The microstructure, porosity, toughness and wear resistance of the Fe-based amorphous coating and composite coatings were studied, respectively. The results show that the addition of AT13 doesn't affect the glassy formation ability of amorphous phase. The porosity of the composite coatings decreases significantly with the increase of the second phase weight fraction, and the porosity of coating with 15 wt% AT13 is only 1.12%. Tribological results indicate that the composite coatings have superior wear resistance than that of the single amorphous coating, such as the lower friction coefficient and wear rate. It was found that the 15 wt% AT13/Fe-based composite coating exhibited the most excellent wear resistance, resulting from the wear rate of which is about a quarter of that of the monolithic amorphous coating under the 300 r/min test conditions. At high sliding speed, the wear mechanism of the composite coating is a combination of fatigue wear, oxidative wear and adhesive wear.

Inductance sensor is one of the commonly used methods in the detection of oil metal particles. The shapes of particles are different, caused by the different forms of wear in oil; however, the effect of particle shapes on the inductive sensors was not under consideration. In order to obtain more accurate measurement results of inductive sensors in metal particle detection and other areas of application, the effect of particle shapes on an inductive sensor is studied in this paper. The inductance change of coil about the ratio of long axis to short axis of particles is obtained in accordance with the experimental validation depending on the cylindrical particles. The results show that the inductance changes are 0.25 nH, 0.32 nH, and 0.92 nH with the ratios of long axis to short axis of particles l/d are 0.67, 1, and 3 with the same volume. It is observed that the inductance change of coil ΔL increases with an increasing ratio of long axis to short axis of particles l/d, which provides a theoretical basis for inductive sensors in metal particle detection and other areas of application.Inductance sensor is one of the commonly used methods in the detection of oil metal particles. The shapes of particles are different, caused by the different forms of wear in oil; however, the effect of particle shapes on the inductive sensors was not under consideration. In order to obtain more accurate measurement results of inductive sensors in metal particle detection and other areas of application, the effect of particle shapes on an inductive sensor is studied in this paper. The inductance change of coil about the ratio of long axis to short axis of particles is obtained in accordance with the experimental validation depending on the cylindrical particles. The results show that the inductance changes are 0.25 nH, 0.32 nH, and 0.92 nH with the ratios of long axis to short axis of particles l/d are 0.67, 1, and 3 with the same volume. It is observed that the inductance change of coil ΔL increases with an increasing ratio of long axis to short axis of particles l/d, which provides a theoretical basis f...

Understanding of the sintering mechanism of nickel nanoparticles in the Ni/YSZ anode is requested for long-term durability of solid oxide fuel cell. To elucidate the effects of a porous structure of the Ni/YSZ anode on the sintering, we investigated the sintering process in the Ni/YSZ anodes with different porosities by using our developed multi-nanoparticle molecular dynamics simulation method. We found that the nickel nanoparticle size significantly increased although the YSZ nanoparticles showed little change during the sintering in all the Ni/YSZ models. Since the decrease in the porosity leads to the decrease in the pore size of the YSZ framework, the sintering of the nickel nanoparticles in the Ni/YSZ model with the less porosity is more prevented by suppressing the neck growth in the small pore. On the other hand, the excessively large porosity increases the distance between the nickel nanoparticles and prevents the nickel nanoparticles from contacting.

We have developed a molecular dynamics (MD) simulation method to investigate the sintering of nickel nanoparticles in the nickel and yttria-stabilized zirconia (Ni/YSZ) anode of a solid oxide fuel ...

Src family kinases (SFKs), a class of non-receptor tyrosine kinases, mediate a wide aspect of cellular signaling pathways that regulate cell proliferation, differentiation, motility and survival. In this study, we identified and characterized for the first time a novel SFK homologue from Litopenaeus vannamei (designated as LvSrc). Sequence analysis showed that LvSrc had a high homology with the identified SFKs, especially those from invertebrates. LvSrc contained the conserved SH3, SH2 and tyrosine kinase domains, as well as the potential phosphorylation and lipid modification sites. Immunofluorescence analysis demonstrated that LvSrc was mostly localized at the plasma membrane and partly resided in the perinuclear vesicle and nucleus or whole cell. Infection with white spot syndrome virus (WSSV) could up-regulate the transcription and expression levels of LvSrc and further induced its phosphorylation, suggesting that LvSrc was implicated in WSSV infection. Furthermore, our co-immunoprecipitation result confirmed the interaction between Src and focal adhesion kinase (FAK) in shrimp, while the phosphorylation of FAK was markedly enhanced by co-expression with LvSrc. In sum, our studies suggested that LvSrc might act in the FAK-regulated signaling pathway during WSSV infection, which would give us a better insight in understanding the role of SKFs in host-virus interactions in crustaceans.

Sintering of Ni particles in the Ni-based anode is a major obstacle to the widespread use of solid oxide fuel cell because the sintering induces the degradation in the anode. The large amount of water vapor in the fuel is known to accelerate the degradation during the operation. However, the detailed accelerated sintering mechanism is unclear. In this study, to clear the accelerated sintering mechanism during the initial stage of the sintering by water vapor, we investigated the adsorption and dissociation of water molecules on the Ni surface as well as the effect of the terminations of O, H, and OH on the interaction between the Ni clusters by density functional theory because the sintering of Ni particles is started by the Ni particles approaching each other due to the attractive interaction between Ni particles at the initial stage. In our adsorption and dissociation calculations, increasing the amount of water vapor facilitates the adsorption of H 2 O molecule on the Ni surface due to the H-bond interaction. Meanwhile, the activation energy for the dissociation of H 2 O molecules on the Ni surface is also lowered with increasing the amount of H 2 O molecules. Then, we calculated the interaction between Ni cluster, and O terminated, OH terminated, and H terminated Ni clusters. We observed that the attractive interaction between Ni cluster and O terminated Ni cluster is larger than that between two Ni clusters in vacuum. Enhancing the attractive interaction is not observed in the H terminated and OH terminated Ni clusters. It indicates that two Ni clusters approaching each other is faster under the water vapor environment than that in vacuum due to the strong attractive interaction caused by the termination of O. Thus, we suggest that the generation of O termination plays an important role in the sintering at the initial stage under the water vapor environment.

Sintering of Ni nanoparticles in a Ni/YSZ porous anode of a solid oxide fuel cell (SOFC) during the long-term operation take places easily due to the high operation temperature, which leads to the degradation of the Ni/YSZ porous electrode. In previous studies, we developed a multi-nanoparticle modeling methodology that can consider the effects of the properties of the porous structure such as porosity and YSZ nanoparticle framework, etc., for investigating the sintering process in the porous structure and revealed that the porous structure plays a critical role in suppression of the sintering [1,2]. Moreover, the porous structure is determined by the framework consisting of many nanoparticles. Thus, the design of the framework structure that can effectively prevent the sintering during the operation is demanded. For this purpose, the investigation of the YSZ nanoparticle size effect on the framework structure and its effect on the sintering is needed, because the framework structure is determined by the nanoparticle size, nanoparticle ratio and so on. However, the mechanism of different sintering behavior by changing the size of YSZ nanoparticle has not been revealed. In this study, we investigated the effect of YSZ nanoparticle size on the sintering of Ni nanoparticles in the Ni/YSZ porous structure by using our multi-nanoparticle sintering simulation based on the large-scale molecular dynamics simulation method. Our results show that Ni nanoparticles make contact with each other and the sintering proceeds by the growth of the contact area between the Ni nanoparticles. Then, we quantified the degree of sintering and found that the degree of sintering in the Ni/YSZ model with the large YSZ nanoparticles compared to Ni nanoparticles is larger than that with the small YSZ nanoparticles compared to Ni nanoparticles. In the Ni/YSZ model with the large YSZ nanoparticles compared to Ni nanoparticles, the framework of large YSZ nanoparticles generates the large pore. The Ni nanoparticles are easy to move in the framework structure, and the sintering of Ni nanoparticles takes place easily. On the other hand, the framework of small YSZ nanoparticles generates the small pore in the Ni/YSZ model with the small YSZ nanoparticles compared to Ni nanoparticles. The framework of small YSZ nanoparticles restrains the movement of the Ni nanoparticles. Thus, the sintering of Ni nanoparticles is inhibited in the Ni/YSZ model with the small YSZ nanoparticles compared to Ni nanoparticles. [1] J. Xu et al., J. Phys. Chem. C 117 (2013) 9663. [2] J. Xu et al., ECS Trans. 57, (2013) 2459.

In this Communication, we use density functional theory (DFT) to examine the fracture properties of ceria (CeO2), which is a promising electrolyte material for lowering the working temperature of solid oxide fuel cells. We estimate the stress-strain curve by fitting the energy density calculated by DFT. The calculated Young's modulus of 221.8 GPa is of the same order as the experimental value, whereas the fracture strength of 22.7 GPa is two orders of magnitude larger than the experimental value. Next, we combine DFT and Griffith theory to estimate the fracture strength as a function of a crack length. This method produces an estimated fracture strength of 0.467 GPa, which is of the same order as the experimental value. Therefore, the fracture strength is very sensitive to the crack length, whereas the Young's modulus is not.