Impurity-induced Shiba bound state in the BCS–BEC crossover regime of two-dimensional Fermi superfluid

For a two-dimensional ultra-cold Fermi superfluid with an effective static magnetic impurity, we theoretically investigated the variation of the Yu–Shiba–Rusinov(YSR) bound state in the Bardeen–Cooper–Schrieffer(BCS) to Bose–Einstein condensation(BEC) crossover regime.Within the framework of mean-field theory, analytical results of the YSR bound state energy were obtained as a function of the interaction parameters.First, when the background Fermi superfluid system stays in the weakly interacting BCS regime, we found that the YSR bound state energy is linearly dependent on the gap parameter with its coefficient slightly different from previous results.Second, we discovered re-entrance phenomena for the YSR state and an upper bound of the strength of the interaction between the paired atoms.By carefully analyzing the bound state energy as a function of the interaction parameters, we obtained a phase diagram showing the existence of the YSR state.Finally, we concluded that the re-entrance phenomena and the critical point can be easily experimentally detected through measurement of radio-frequency spectroscopy and density of states using current experimental techniques.

Thermal insulating and fire-retardant Si_(3)N_(4) nanowire membranes resistant to high temperatures up to 1300℃

Superior thermal insulating and fire-retardant ceramic membranes are urgently demanded in the aerospace,construction,and chemical engineering industries.However,the generic characteristics of ceramic membranes,such as brittleness,structural collapse,and crystallization-induced pulverization behavior,present a great plague to their practical applications.Herein,we report a highly flexible,mechanically stable,fire-retardant,and high-temperature-resistant ceramic membrane based on the interlocked Si_(3)N_(4) nanowires formed by the precursor pyrolysis method.The Si_(3)N_(4) nanowire membrane(SNM)has excellent high-temperature resistance under alcohol lamps and butane spray lance.The thermal insulation with a thermal conductivity as low as 0.056 W m^(-1)K^(-1)can be attributed to the high porosity of SNM,which makes it a desirable candidate for heat insulators under harsh conditions.More importantly,SNM exhibits thermal stability and robust mechanical properties in the range of 25 to 1300℃.The high-temperature resistance of SNM up to 1300℃is achieved by the four stages:Si3 N4 nanowires,Si_(3)N_(4)@SiO_(2) nanowires,SiO_(2) nanowires,and bead-like SiO_(2) nanowires.After heat-treated at 1300℃,the macroscopic size of SNM does not change significantly,and the interlocked structure is still maintained.Furthermore,SNM still maintains excellent mechanical properties,with tensile strength as high as 0.26 MPa.This work provides a facile method for fabricating excellent thermal insulating and fire-retardant ceramic membranes,showing prospective application prospects in the era of thermal insulating materials.

Synchronously constructing networked Si_(3)N_(4) nanowires and interconnected graphene inside carbon fiber composites for enhancing mechanical, friction and anti-ablation properties

Carbon fiber(C_(f))reinforced pyrolytic carbon(PyC)composites simultaneously possessing robust mechanical strength,excellent friction performances and outstanding anti-ablation properties are demanded for advanced aerospace applications.Efficient architecture design and optimization of composites are promi-nent yet remain high challenging for realizing the above requirements.Herein,binary reinforcements of networked silicon nitride nanowires(Si_(3)N_(4) nws)and interconnected graphene(GE)have been successfully constructed into C f/PyC by precursor impregnation-pyrolysis and chemical vapor deposition.Notably,net-worked Si_(3)N_(4) nws are uniformly distributed among the carbon fibers,while interconnected GE is firmly rooted on the surface of both networked Si_(3)N_(4) nws and carbon fibers.In the networked Si_(3)N_(4) nws and interconnected GE reinforced C_(f)/PyC,networked Si_(3)N_(4) nws significantly boost the cohesion strength of PyC,while GE markedly improves the interface bonding of both Si_(3)N_(4) nws/PyC and fiber/PyC.Benefiting from the synergistic reinforcement effect of networked Si_(3)N_(4) nws and interconnected GE,the C_(f)/PyC have a prominent enhancement in mechanical(shear and compressive strengths increased by 119.9% and 52.84%,respectively)and friction(friction coefficient and wear rate reduced by 25.40% and 60.10%,respectively)as well as anti-ablation(mass ablation rate and linear ablation rate decreased by 71.25% and 63.01%,respectively).This present strategy for networked Si_(3)N_(4) nws and interconnected GE reinforced C_(f)/PyC provides a dominant route to produce mechanically robust,frictionally resisting and ablatively resistant materials for use in advanced aerospace applications.

Pervaporation performance and characterization of hydrophilic ZSM-5 zeolite membranes for high inorganic acid and inorganic salts

The hydrophilic ZSM-5 zeolite membranes are applied to separate the inorganic acid solutions and inorganic acid/inorganic salt mixtures by pervaporation,and the membrane presents good stability,dehydration,and desalination performance.Influences of inorganic acid type(H_(2)SO_(4),H_(3)PO_(4),HNO_(3),and HCl),H_(2)SO_(4)concentration(1e6 mol·L^(-1)),test temperature(60-90℃)and inorganic acid/inorganic salt type(2 mol·L^(-1)H_(2)SO_(4)and sulfate,2 mol·L^(-1)H3PO4 and phosphate)on the pervaporation performance are investigated in this work.Either for concentrating 3%(mass)H_(2)SO_(4)solution or consecutive dehydrating 20%(mass)H_(2)SO_(4)solution,the hydrophilic ZSM-5 zeolite membrane has a good dehydration performance and stability.Even though the H_(2)SO_(4)concentration and test temperature are increased to 6 M and 90℃,only H_(2)O molecules could pass through the membrane and pH value of the permeation is kept neutral.Besides,the membrane has good dehydration and desalination performance for H_(2)SO_(4)/sulfates and H_(3)PO_(4)/phosphate mixtures,and the rejection of natrium salt,molysite,and magnesium is almost 100%.