摘要：We find that the coherent state projection operator representation of symplectic transformation constitutesa loyal group representation of symplectic group. The result of successively applying squeezing operators on numberstate can be easily derived.

摘要：Electrochemical reduction from nitrate into ammonia is a chance for nitrate removal from drinking water,while at higher concentrations,this 8-electron reduction process could even become relevant for energy storage,high conversions and low onset potentials ***,we report the synthesis and analysis of a NiFe_(2)O_(4)/C-MS hybrid system made by a molten-salt strategy where the Ni-Fe oxide spinel nanoparticles act as the active center for electrochemical nitrate(NO_(3)−)reduction reaction,while the microporous carbon serves as a conductive support to form a cohesive electrode *** NiFe_(2)O_(4)/C-MS catalyst achieves a maximum NH3 yield rate of 5.4 mg mgcat.^(−1)h^(−1)and Faradaic efficiency of 98%at−0.6 V versus reversible hydrogen *** NiFe_(2)O_(4)nanoparticles buried into microporous carbon,the onset potential decreases *** propose that this reduction originates from charge redistribution in NiFe_(2)O_(4)in the electronic heterojunction with carbon,while enhanced electrolyte diffusion in microporous carbon facilitates high conversion *** functional theory calculations clarify the low energy barrier on NiFe_(2)O_(4),highlighting the essential role of Ni in activating Fe *** COMSOL Multiphysics simulations demonstrate that the microporous curled carbon accelerates NO_(3)−transport and enhances adsorption on the reactive *** work offers insights for designing carbon-based nanocomposites for efficient nitrate reduction electrocatalysis.

摘要：We extend the method of searching “eigen-operator” of the square of the Schroedinger operator to the interaction picture, which not only helps to construct Hamiltonians of two kinds of parametric amplifiers but also leads to a new uncertainty relation regarding to the free Hamiltonian and the interacting Hamiltonian.

摘要：Laminar flow design is one of the most effective ways to reduce the drag of a commercial aircraft by expanding the laminar flow region on the surface of the aircraft. As material science develops, the emergence of new materials such as low surface energy materials has offered new choices for laminar flow design of commercial aircraft. Different types of low surface energy micro-nano coatings are prepared to verify the effects on the boundary layer transition position and the drag of the airfoil through wind tunnel tests. The infrared thermal imaging technology is adopted for measuring the boundary layer transition, while the momentum integral approach is employed to measure the drag coefficient through a wake rake. Infrared thermal imaging results indicate that the coatings are capable of moving backward the boundary layer transition position at both a low velocity of Mach number 0.15 and a high velocity of Mach number 0.785. Results of the momentum integral approach demonstrate that the drag coefficients are reduced obviously within the cruising angle of attack range from 1° and 5° by introducing the low surface energy micro-nano coating technology.

摘要：Marine biofouling is a major issue deteriorating the service performance and lifespan of marine *** development of a durable,long-term,and environment-friendly antifouling coating is therefore of significant importance but still a critical challenge in maritime ***,we developed a Cu-Ti composite antifouling coating with micron-sized alternating laminated-structure of Cu/Ti by plasma spraying of mechanically mixed Cu/Ti *** coating was designed to enable controlled release of Cu ions through galvanic dissolution of Cu laminates from the Cu/Ti micro-galvanic cell in aqueous *** showed that remarkable antifouling efficiency against bacterial survival and adhesion up to~100%was achieved for the Cu-Ti ***/Ti micro-galvanic cell was in-situ formed within Cu-Ti coating and responsible for its Cu ions *** successive dissolution of Cu laminates resulted in the formation of micro-channels under Ti laminates near surface,which contributed to controlled slow Cu ions release and self-polishing ***,environment-friendly antifouling capability and∼200%longer antifouling lifetime than that of the conventional organic antifouling coatings can be achieved for the Cu-Ti *** the other hand,as compared to the conventional organic antifouling coatings,the Cu-Ti composite coating presented much higher mechanical durability due to its strong adhesion strength,excellent mechanical properties,and two orders lower wear *** present laminated Cu-Ti coating exhibits combination of outstanding antifouling performance and high mechanical durability,which makes this coating very potentially candidates in marine antifouling application.

摘要：Estimating long-term creep deformation and life of materials is an effective way to ensure the service safety and to reduce the cost of long-term integrity evaluation of high temperature structural *** the 1980 s, the θ projection model has been widely used for predicting creep lives due to its ability to capture the characteristic transitions observed in creep curves obtained under constant true stress conditions. However, the creep rupture behavior under constant load or engineering stress conditions cannot be simulated accurately using this model because of the different stress states. In this paper, creep curves obtained under constant load conditions were analyzed using a modified θ projection model by considering the increase in true stress with creep deformation during the creep tests. This model is expressed as ε = θ_1(1-e^(-θ_2t)) + θ3 e^(θ_4e^θ5^εt)-1, and was validated using the creep curves of K465 and DZ125 superalloys tested at a range of temperatures and engineering stresses. Moreover, it was shown that the predictive capability of the modified θ projection model was significantly improved over the original one, as it reduces the prediction uncertainty from a range of 10% to 20% to below 5%. Meanwhile,it was shown that the model can be reasonably used for predicting constant stress creep conditions, when appropriate parameters are used. The prediction performance of the modified model will be discussed in another paper. The results of this study show great potential for the evaluation and assessment of the service safety of structural materials used in applications where designs are limited by creep deformation.

摘要：Periosteum,a membrane covering the surface of the bone,plays an essential role in maintaining the function of bone tissue—and especially in providing nourishment and vascularization during the bone regeneration ***,most artificial periostea have relatively weak mechanical strength and a rapid degradation rate,and they lack integrated angiogenesis and osteogenesis *** this study,a bi-layer,biomimetic,artificial periosteum composed of a methacrylated gelatin–nano-hydroxyapatite(GelMA-nHA)cambium layer and a poly(N-acryloyl 2-lycine)(PACG)-GelMA-Mg^(2+)fibrous layer was fabricated via 3D *** GelMA-nHA layer is shown to undertake the function of improving osteogenic differentiation of rat bone marrow mesenchymal stem cells with the sustainable release of Ca^(2+) from nHA *** hydrogen-bonding-strengthened P(ACG-GelMA-L)-Mg^(2+)hydrogel layer serves to protect the inner defect site and prolong degradation time(60 days)to match new bone ***,the released magnesium ion exhibits a prominent effect in regulating the polarization phenotype of macrophage cells into theM2 phenotype and thus promotes the angiogenesis of the human umbilical vein endothelial cells in *** bi-layer artificial periosteum was implanted into a critical-sized cranial bone defect in rats,and the 12-week post-operative outcomes demonstrate optimal new bone regeneration.

摘要：As a β stabilizing element in Ti-based alloys,the effect of Mo on phase constitution,microstructure,mechanical and shape memory properties was *** compositions of Ti-xMo-3Sn alloys(where x=2,4,6,at.%) were prepared by arc melting.A binary composition of Ti-6 Mo alloy was also prepared for ***-xMo-3Sn alloys show low hardness and high ductility with 90% reduction in thickness while Ti-6 Mo alloy shows high hardness,brittle behavior,and poor *** emission scanning electron microscopy(FESEM) reveals round morphology of athermal ω(ωath) *** presence of ωath phase is also confirmed by X-ray diffraction(XRD)in both as-cast and solution-treated and quenched *** optical microscopy(OM) and FESEM show that the amount of martensite forming during quenching decreases with an increase in Mo content,which is also due to β→ω *** hardness trends reinforce the presence of ωath *** shape memory effect(SME) of 9% is the highest for Ti-6 Mo-3Sn *** SME is trivial due to ωath phase formation;however,the increase in SME is observed with an increase in Mo content,which is due to the reverse transformation from ωath and the stress-induced martensitic *** addition,a new and very simple method was designed and used for shape memory effect measurement.

摘要：The development of low-cost and highly efficient bifunctional electrocatalysts toward oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is of critical importance for clean energy devices such as fuel cells and metal-air ***,a sophisticated na nostructure composed of CoS,Co and MoC nanoparticles incorporated in N and S dual-doped porous carbon nanofibers(CoS/Co/MoC-N,SPCNFs)as a high-efficiency bifunctional electrocatalyst is designed and synthesized via an efficient multistep *** as-prepared CoS/Co/MoC-N,S-PCNFs exhibit a positive half-wave potential(E1/2)of0.871 V for ORR and a low overpotential of 289 mV at 10 mA/cm^(2) for OER,outperforming the non-noble metal-based catalysts ***,the assembled Zn-air battery based on CoS/Co/MoC-N,SPCNFs delivers an excellent power density(169.1 mW/cm^(2)),a large specific capacity(819.3 mAh/g)and robust durability,demonstrating the great potential of the as-developed bifunctional electrocatalyst in practical *** work is expected to inspire the design of advanced bifunctional nonprecious metal-based electrocatalysts for energy storage.

摘要：The multi-component composition characteristics of high-temperature near-α Ti alloys were investigated in the present work by means of a cluster formula approach. The uniform cluster formula [CN12 cluster](glue atom)3 for the hexagonal close-packed α solid solution was first obtained based on the Friedel oscillation theory, with a total atom number in the formula of Z = 16. Then it was analyzed that the Z values in the cluster composition formulas of typical near-α Ti alloys are within the range of Z = 16.0016.30, being perfectly consistent with the ideal Z = 16. Based on it, a series of new alloys with Z = 16 and with Nb/Ta substitution for Mo in Ti1100 alloy were designed, suction-cast into φ 6 mm rods, and then heat-treated with solid solution and aging. It was found that the alloy with co-addition of Mo, Ta and Nb has a high strength and good ductility at both room and high temperatures. More importantly, the additions of Nb and Ta can contribute to the formation of continuous and compact Al2O3 scales, resulting in an obvious improvement of oxidation resistances at both 923 K and 1073 K. The effects of Mo, Ta and Nb on the oxidation behaviors of the designed alloys at 1073 K were further discussed.