查看更多>>摘要：Along with a wide range of applications,the surface-enhanced Raman spectroscopy(SERS)is a promi-nent analytical technique to recognize and detect molecules and materials even at an extremely low mo-lar concentration.In this work,a unique hybrid SERS platform is demonstrated by the incorporation of molybdenum disulfate(MoS2)nanoparticles(NPs)onto the core-shell AuPt hybrid NPs(HNPs)for the en-hanced molecular Raman vibration of crystal violet(CV).The hybrid platform takes the advantage of both the electromagnetic mechanism(EM)offered by the AuPt HNPs and chemical mechanism(CM)owing to the MoS2 NPs.The distinctive core-shell morphology of AuPt HNPs with the high-density background Au NPs is attained by a unique two-step solid-state dewetting method,which can offer a high concentration of electromagnetic hot spots.At the same time,the MoS2 NPs can provide an ample charge transfer with abundant active sites.Through the hybrid SERS approach,a dramatic SERS enhancement of CV Raman vibration is demonstrated,and the SERS capability is thoroughly studied.In addition,the finite-difference time-domain(FDTD)simulations provide a deeper understanding of the electromagnetic field distribu-tions for various configurations of nanostructures and their hybrid combinations:i.e.,HNPs,alloy NPs,MoS2/HNPs configurations.
查看更多>>摘要：Through in-situ TEM observation during 30 keV H2+-He+dual-beam irradiation at 723 K,the reaction and transformation of dislocation loops in pure Mo were investigated,especially for<100>loops.Ir-radiation could directly cause the formation of 1/2<111>loops and<100>loops,but 1/2<111>loops were dominant.In-situ observation confirmed the formation mechanism of<100>loops,including direct irradiation induced mechanism,1/2<111>loop direct conversion mechanism,and reaction mechanism of two 1/2<111>loops.Meanwhile,the reaction of two 1/2<111>loops to produce<100>loop should not require the strict size similarity condition.The reaction between 1/2<111>loops could also pro-duce 1/2<111>loop,which was essentially a process in which one loop absorbed another one.The yield strength increment caused by irradiation-induced loops was analyzed,and its saturation value reached 0.48 GPa at 0.06 dpa.Compared with single He+irradiation,the number density and average diame-ter of loops increased significantly and more serious damage was caused under the synergistic effect of hydrogen and helium.The mechanism based on in-situ experimental observation was discussed in depth.
查看更多>>摘要：The principle and control for solidification present crucial challenges.Through in situ and real time ob-servation on the solidification of M50 bearing steel,here we discovered that the base of conventional dendritic arms is constituted by a primary semi-solid matrix.Due to the superimposition of temperature fluctuations from the large to the subtle scale,multi-scale dendritic patterns will sequentially emerge and evolve in the primary semi-solid matrix.These findings redefine the essence of multi-scale dendrites as the multi-scale segregation patterns in the primary semi-solid matrix,reconstitute the time and space sequence in the formation of multi-scale dendrites,and reveal the superimposition of temperature fluc-tuation as the driving principle.These new understandings will fundamentally influence the solidification field.These results also indicate important engineering applications,such as designing multi-scale den-drites,controlling the dendritic segregation and eliminating the detrimental eutectics.
查看更多>>摘要：A novel self-healing coating with photothermal and pH dual-responsive properties has been de-signed to protect carbon steel against corrosion by loading the stimuli-responsive microcapsules into a shape memory epoxy coating.The sandwich-like microcapsules were based on reduced graphene oxide/mesoporous silica(rGO@MS)assembled with a pH-responsive poly(N,N-dimethylaminoethyl methacrylate)(PDMAEMA)layer,and were loaded with benzotriazole(BTA)inhibitors(abbreviated as rGO@MS-P-BTA).Under near-infrared(NIR)light irradiation,the prominent photothermal effect of rGO could not only elevate the coating temperature to activate the shape memory effect and close the coating scratch,but also facilitate the release of corrosion inhibitors to suppress the corrosion activity.Moreover,the PDMAEMA as a pH-driven"gatekeeper"realized the controlled release of BTA from microcapsules at acid conditions.The surface morphology analysis,electrochemical impedance spectroscopy(EIS),and scanning electrochemical microscopy(SECM)were performed to evaluate the self-healing performance of the composite coatings.The results showed that the combination of NIR light and pH-responsive self-healing effects endowed the coating with short healing time and prominent healing efficiency.
查看更多>>摘要：Tetrakis hydroxymethyl phosphonium sulfate(THPS)was enhanced by a 14-mer Peptide A,with its core 12-mer sequence mimicking part of Equinatoxin Ⅱ protein,in the mitigation of sulfate reducing Desul-fovibrio ferrophilus MIC(microbiologically influenced corrosion)of X80 carbon steel.Results proved that 50 ppm(w/w)THPS was sufficient to mitigate the D.ferrophilus biofilm,and its very agressive MIC(19.7 mg/cm2 in 7 days or 1.31 mm/a),but not 20 ppm THPS.To achieve effective mitigation at a low dosage of THPS,biofilm-dispersing Peptide A was added to 20 ppm THPS in the culture medium.Sessile cell counts were reduced by 2-log and 4-log after enhancement by 10 ppb and 100 ppb Peptide A,respectively.En-hancement efficiency(further reduction in corrosion rate)reached 69％for 10 ppb Peptide A and 83％for 100 ppb Peptide A compared with 20 ppm THPS alone treatment,indicating that Peptide A was a good biocide enhancer for THPS.
Joung Sik SuhByeong-Chan SuhSang Eun LeeJun Ho Bae...
52-63页
查看更多>>摘要：The present study proposes a methodology for predicting the mechanical properties of AZ61 and AZ91 alloys associated with microstructure,texture and aging parameters and estimating predictor importance.For this,we investigate quantitative correlations between microstructure,texture and mechanical prop-erties of aged AZ61 and AZ91 rods through machine learning.This regression analysis focuses on the precipitation behavior of Mg17Al12 as the main second phase of Mg-Al-Zn alloys with respect to aging conditions.To simplify data generation,only SEM images were used to quantify the features of discontin-uous and continuous precipitates.To overcome the lack of data and make the most of the measured data,we devised a method to extend the existing dataset by a factor of 9 using the mean and standard devi-ation of the measured data.Artificial neural networks predicted tensile and compressive yield strengths and resultant yield asymmetry with a high accuracy of over 98％using 11 predictors for a total of 288 datasets.Decision tree learning quantitatively assessed the importance of predictors in determining the mechanical properties of aged AZ61 and AZ91 rods.
查看更多>>摘要：As an alternative for lithium-ion batteries(LIBs),sodium-ion batteries(SIBs)have lately received tremen-dous interest due to their abundant reserves as well as low cost.Nevertheless,the lack of suitable an-ode materials severely hinders the application of sodium-ion batteries.TiS2 is elected as a representative material owing to its unique layered structure.But it always suffers from capacity fade due to poor elec-trochemical kinetics and structural stability.In this work,we fabricate a pre-potassiated TiS2 as a host material for sodium storage by an electrochemical pre-potassiation strategy.The intercalation/extraction mechanism,structural changes and reaction kinetics are completely investigated to reveal the outstand-ing electrochemical property of pre-potassiated TiS2 electrode.It turns out that the large interlayer space of pre-potassiated TiS2 is conducive to the diffusion of sodium ions,inducing the reduction of entropic barrier for the electrochemical reactions.In addition,the pre-potassiated host structure is still firmly maintained upon repeated cycles.Therefore,the pre-potassiated TiS2 presents superior rate capability(165.9 mA h g-1 at 1 C and 132.1 mA h g-1 at 20 C)and long-term cycling stability(85.3％capacity retention at 5 C after 500 cycles)for SIBs.This research provides an avenue to construct long-life sodium energy storage systems based on pre-potassiated TiS2.
查看更多>>摘要：Heterostructured(HS)material with extraordinary mechanical properties has been regarded as one of the most promising structural materials.Here,we reported a new strategy for preparing heterostructured pure titanium laminates that possess a good combination of strength and ductility by combining gradi-ent structure(GS)and heterogeneous lamella structure(HLS).The deformation characteristic versus mi-crostructure evolution of GS/HLS titanium laminates,namely the strain partitions between different-sized grains(480-25 μm)was visualized using a scanning electron microscope(SEM)equipped with electron backscattered diffraction(EBSD)mode combined with the digital image correlation(SEM-DIC)with an ultrahigh spatial resolution for the first time.As a result,the hetero-deformation of unique GS/HLS struc-ture by the characteristic of strain partitions could be accurately captured.While the hetero-deformation could result in the hetero-deformation induced(HDI)stress strengthening and HDI hardening,which were regarded as the key reason that the resulting GS/HLS Ti laminates showed a superior combina-tion of strength and ductility.This could promote a more in-depth understanding of the strengthening-toughening mechanism of heterostructured material.
查看更多>>摘要：The anelastic deformation behavior of Pd20Pt20Cu20Ni20P20 high-entropy metallic glass was probed by monitoring the stress relaxation and recovery processes.The stress relaxation under consecutive strain steps can be described by the Kohlrausch-Williams-Watts(KWW)function.In addition,considering a hi-erarchy of relaxation processes related to the structural heterogeneity,a constitutive model is proposed in order to describe the whole process of stress relaxation and determine the contribution of different time scales.Moreover,a crossover from stochastic activation to percolation of flow defects with the ultimate strain can be observed during stress relaxation process.The anelastic recovery process after a strain step is studied as a function of the initial strain level and characterized by means of a direct spectrum analy-sis.The peaks in the recovery time-spectra revealed the evolution of flow defects in Pd20Pt2oCu20Ni2oP20 high-entropy metallic glass.The understanding of the atomic free-volume zones effect and the anelastic deformation provides important insight into how atomic structural features affect the deformation be-havior of high-entropy metallic glasses,and may provide a new avenue into the improvement of their mechanical properties.
查看更多>>摘要：Revealing the magnetic coupling nature of boundary defects is crucial for in-depth understanding of the behavior and properties of magnetic materials and devices.Here,magnetite(i.e.,Fe3O4)thin films were grown epitaxially on(100)SrTiO3 single-crystal substrates by pulsed laser deposition.Atomic-scale scan-ning transmission electron microscopy characterizations reveal that three types of antiphase boundaries(APBs)are formed in the Fe3O4 thin film.They are the(100)APB that is formed on the(100)plane with a crystal translation of(1/4)a[011],the type Ⅰ and type Ⅱ(110)APBs that are both formed on the(110)plane with the same crystal translation of(1/4)a[101]but different terminated atomic planes.The type Ⅰ(110)APB is terminated at the atomic plane with mixed tetrahedral-and octahedral-sites Fe atoms,the type Ⅱ(110)APB is terminated at the octahedral-site Fe plane.First-principles calculations reveal that the(100)APB and the type Ⅰ(110)APB tend to form the ferromagnetic coupling that will not decrease the spin polarization of Fe3O4 films,while the type Ⅱ(110)APB prefers to form the antiferromagnetic coupling that will degrade the magnetic properties.The magnetic coupling modes of the APBs are closely related to the Fe-O-Fe bond angles across the boundaries.
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