Design and characterization of biodegradable Mg-Zn-Ag metallic glasses

In order to develop the Mg-Zn-Ag metallic glasses(MGs)for biodegradable implant applications,the glass formation ability(GFA)and biocompatibility of Mg-Zn-Ag alloys were investigated using a combination of the calculation of phase diagrams(CALPHAD)and experimental measurements.High GFA potentiality of two alloy series,specifically Mg_(96-x)Zn_xAg_(4)and Mg_(94-x)Zn_xAg_6(x=17,20,23,26,29,32,35),was predicted theoretically and then substantiated through experimental testing.X-ray diffraction(XRD)and differential scanning calorimetry(DSC)techniques were used to evaluate the crystallinity,GFA,and crystallization characteristics of these alloys.The results showed that compositions between Mg_(73)Zn_(23)Ag_(4)and Mg_(64)Zn_(32)Ag_(4)for Mg_(96-x)Zn_xAg_4,Mg_(66)Zn_(28)Ag_(6)and Mg_(63)Zn_(31)Ag_(6for)Mg_(94-x)Zn_xAg_(6)displayed a superior GFA.Notably,the GFA of the Mg_(96-x)Zn_xAg_(4)series was better than that of the Mg_(94-x)Zn_xAg_(6)series.Furthermore,the Mg_(70)Zn_(26)Ag_4,Mg_(74)Zn_(20)Ag_6,and Mg_(71)Zn_(23)Ag_(6)alloys showed acceptable corrosion rates,good cytocompatibility,and positive effects on cell proliferation.These characteristics make them suitable for applications in medical settings,potentially materials as biodegradable implants.

Prediction of Hot Deformation Behavior of 7Mo Super Austenitic Stainless Steel Based on Back Propagation Neural Network

The hot compression tests of 7Mo super austenitic stainless(SASS)were conducted to obtain flow curves at the temperature of 1000-1200℃and strain rate of 0.001 s^(-1)to 1 s^(-1).To predict the non-linear hot deformation behaviors of the steel,back propagation-artificial neural network(BP-ANN)with 16×8×8 hidden layer neurons was proposed.The predictability of the ANN model is evaluated according to the distribution of mean absolute error(MAE)and relative error.The relative error of 85%data for the BP-ANN model is among±5%while only 42.5%data predicted by the Arrhenius constitutive equation is in this range.Especially,at high strain rate and low temperature,the MAE of the ANN model is 2.49%,which has decreases for 18.78%,compared with conventional Arrhenius constitutive equation.

Vacancy engineering mediated hollow structured ZnO/ZnS S-scheme heterojunction for highly efficient photocatalytic H_(2) production

Designing a step-scheme(S-scheme)heterojunction photocatalyst with vacancy engineering is a reliable approach to achieve highly efficient photocatalytic H_(2)production activity.Herein,a hollow ZnO/ZnS S-scheme heterojunction with O and Zn vacancies(VO,Zn-ZnO/ZnS)is rationally constructed via ion-exchange and calcination treatments.In such a photocatalytic system,the hollow structure combined with the introduction of dual vacancies endows the adequate light absorption.Moreover,the O and Zn vacancies serve as the trapping sites for photo-induced electrons and holes,respectively,which are beneficial for promoting the photo-induced carrier separation.Meanwhile,the S-scheme charge transfer mechanism can not only improve the separation and transfer efficiencies of photo-induced carrier but also retain the strong redox capacity.As expected,the optimized VO,Zn-ZnO/ZnS heterojunction exhibits a superior photocatalytic H_(2) production rate of 160.91 mmol g^(-1)h^(-1),approximately 643.6 times and 214.5 times with respect to that obtained on pure ZnO and ZnS,respectively.Simultaneously,the experimental results and density functional theory calculations disclose that the photo-induced carrier transfer pathway follows the S-scheme heterojunction mechanism and the introduction of O and Zn vacancies reduces the surface reaction barrier.This work provides an innovative strategy of vacancy engineering in S-scheme heterojunction for solar-to-fuel energy conversion.

陈嘉川教授荣获2023年度何梁何利基金科学与技术创新奖

本刊讯(齐鲁工大消息)何梁何利基金2023年度颁奖大会12月19日在北京钓鱼台国宾馆举行,中共中央政治局常委、国务院副总理丁薛祥出席颁奖大会并讲话。齐鲁工业大学(山东省科学院)生物基材料与绿色造纸国家重点实验室主任陈嘉川教授荣获何梁何利基金科学与技术产业创新奖,开创齐鲁工业大学历史。

基于虚拟现实技术驱动的高校新工科教学改革路径探索——以创新方法类课程为例

随着科技的不断发展和社会的不断进步,高等教育也面临着新的挑战和机遇。新工科教育作为一种新的教育理念,强调培养学生的创新能力和实践能力,对高校教学提出了更高的要求。而虚拟现实技术作为一种新兴的教学手段,为高校教学改革提供了新的可能性。如何基于虚拟现实技术驱动更好地改革高校新工科教学,提升学生的创新能力和实践能力,是值得教育工作者深入探讨的重要课题。对此,以创新方法类课程为例,通过分析虚拟现实技术在高校新工科教学改革中的优势,进而探究基于虚拟现实技术的创新方法类课程教学改革路径,以期为教育工作者提供有益的参考和借鉴。

Enhancement of the formic acid electrooxidation activity of palladium using graphene/carbon black binary carbon supports

Combinations of graphene(Gr)and carbon black(C)were employed as binary carbon supports to fabricate Pd‐based electrocatalysts via one‐pot co‐reduction with Pd2+.The electrocatalytic performance of the resulting Pd/Gr‐C catalysts during the electrooxidation of formic acid was assessed.A Pd/Gr0.3C0.7(Gr oxide:C=3:7,based on the precursor mass ratio)electrocatalyst exhibited better catalytic performance than both Pd/C and Pd/Gr catalysts.The current density generated by the Pd/Gr0.3C0.7catalyst was as high as102.14mA mgPd?1,a value that is approximately3times that obtained from the Pd/C(34.40mA mgPd?1)and2.6times that of the Pd/Gr material(38.50mA mgPd?1).The anodic peak potential of the Pd/Gr0.3C0.7was120mV more negative than that of the Pd/C and70mV more negative than that of the Pd/Gr.Scanning electron microscopy images indicated that the spherical C particles accumulated on the wrinkled graphene surfaces to form C cluster/Gr hybrids having three‐dimensional nanostructures.X‐ray photoelectron spectroscopy data confirmed the interaction between the Pd metal and the binary Gr‐C support.The Pd/Gr0.3C0.7also exhibited high stability,and so is a promising candidate for the fabrication of anodes for direct formic acid fuel cells.This work demonstrates a simple and cost‐effective method for improving the performance of Pd‐based electrocatalysts,which should have potential industrial applications.

Ti_(3)C_(2) MXene co-catalyst assembled with mesoporous TiO_(2) for boosting photocatalytic activity of methyl orange degradation and hydrogen production

Photocatalytic degradation and hydrogen production using solar energy through semiconductor photocatalysts are deemed to be a powerful approach for solving environmental and energy crisis.However,the biggest challenge in photocatalysis is the efficient separation of photo-induced carriers.To this end,we report that the mesoporous TiO_(2)nanoparticles are anchored on highly conductive Ti_(3)C_(2)MXene co-catalyst by electrostatic self-assembly strategy.The constructed mesoporous TiO_(2)/Ti_(3)C_(2)composites display that the mesoporous TiO_(2)nanoparticles are uniformly distributed on the surface of layer structured Ti_(3)C_(2)nanosheets.More importantly,the as-obtained mesoporous TiO_(2)/Ti_(3)C_(2)composites reveal the significantly enhanced light absorption performance,photo-induced carriers separation and transfer ability,thus boosting the photocatalytic activity.The photocatalytic methyl orange degradation efficiency of mesoporous TiO_(2)/Ti_(3)C_(2)composite with an optimized Ti_(3)C_(2)content(3 wt%)can reach 99.6%within 40 min.The capture experiments of active species confirm that the·O_(2)-and·OH play major role in photocatalytic degradation process.Furthermore,the optimized mesoporous TiO_(2)/Ti_(3)C_(2)composite also shows an excellent photocatalytic H2 production rate of 218.85μmol g^(-1)h^(-1),resulting in a 5.6 times activity as compared with the pristine mesoporous TiO_(2)nanoparticles.This study demonstrates that the MXene family materials can be applied as highly efficient noble-metal-free co-catalysts in the field of photocatalysis.

Evaluation of residual stress and corrosion behaviour of electroless plated Ni-P/Ni-Mo-P coatings

Single Ni-P and Ni-Mo-P coatings as well as duplex Ni-P/Ni-Mo-P coatings with the same compositions were prepared by electroless plating.The residual stresses of the coatings on the surface and cross sections were measured by nanoindentation and AFM analysis,and the corrosion behaviour of the coatings in10%HCl solution was evaluated by electrochemical methods,to establish the correlation between the residual stresses and corrosion behaviour of the coatings.The results showed that the single Ni-P and duplex Ni-P/Ni-Mo-P coatings presented residual compressive stresses of241and206MPa respectively,while the single Ni-Mo-P coating exhibited a residual tensile stress of257MPa.The residual compressive stress impeded the growth of the pre-existing porosity in the coatings,protecting the integrity of the coating.The duplex Ni-P/Ni-Mo-P coatings had better corrosion resistance than their respective single coating.In addition,the stress states affect the corrosive form of coatings.

Microstructure and electrical conductivity of electroless copper plating layer on magnesium alloy micro-arc oxidation coating

In order to impart electrical conductivity to the magnesium alloy micro-arc oxidation(MAO)coating,the electroless copper plating was performed.Effects of plating temperature and complexing agent concentration on the properties of the electroless copper plating layers were studied by measuring their microstructure,corrosion resistance and electrical conductivity.It was found that the optimized plating temperature was 60°C,and the most suitable value of the complexing agent concentration was 30 g/L.Under this condition,a complete and dense plating layer could be obtained.The formation mechanism of the plating layer on magnesium alloy MAO coating was analyzed.A three-stage model of the plating process was proposed.The square resistance of the plated specimen was finally reduced to 0.03Ω/□after the third stage.Through electroless copper plating,the MAO coated sample obtained excellent electrical conductivity without significantly reducing its corrosion resistance.

Effects of punch velocity on microstructure and tensile properties of thixoforged Mg2Sip/AM60B composite

The effects of punch velocity on the microstructures and tensile properties of Mg2 Sip/AM60 B composite were investigated.In comparison,the tensile properties of the permanent mold casting of this composite were also analyzed.The results indicate that the punch velocity obviously influences the microstructure through changing the secondary solidification behaviors and semisolid deformation mechanisms.The variations of the microstructures and deformation mechanisms are responsible for the changes in tensile properties and fracture modes of the composites.The best comprehensive tensile properties of this composite are obtained under the punch velocity of 60 mm/s.The resulting ultimate tensile strength and elongation of the composite are found to be 198 MPa and 10.2%,respectively.The excellent tensile properties of the thixoforged composite are ascribed to the elimination of porosities and the work hardening.

New strategy of S,N co‐doping of conductive‐copolymer‐derived carbon nanotubes to effectively improve the dispersion of PtCu nanocrystals for boosting the electrocatalytic oxidation of methanol

Efficacious regulation of the geometric and electronic structures of carbon nanomaterials via the introduction of defects and their synergy is essential to achieving good electrochemical performance.However,the guidelines for designing hybrid materials with advantageous structures and the fundamental understanding of their electrocatalytic mechanisms remain unclear.Herein,superfine Pt and PtCu nanoparticles supported by novel S,N‐co‐doped multi‐walled CNT(MWCNTs)were prepared through the innovative pyrolysis of a poly(3,4‐ethylenedioxythiophene)/polyaniline copolymer as a source of S and N.The uniform wrapping of the copolymer around the MWCNTs provides a high density of evenly distributed defects on the surface after the pyrolysis treatment,facilitating the uniform distribution of ultrafine Pt and PtCu nanoparticles.Remarkably,the Pt_(1)Cu_(2)/SN‐MWCNTs show an obviously larger electroactive surface area and higher mass activity,stability,and CO poisoning resistance in methanol oxidation compared to Pt/SN‐MWCNTs,Pt/S‐MWCNTs,Pt/N‐MWCNTs,and commercial Pt/C.Density functional theory studies confirm that the co‐doping of S and N considerably deforms the CNTs and polarizes the adjacent C atoms.Consequently,both the adsorption of Pt1Cu2 onto the SN‐MWCNTs and the subsequent adsorption of methanol are enhanced;in addition,the catalytic activity of Pt_(1)Cu_(2)/SN‐MWCNTs for methanol oxidation is thermodynamically and kinetically more favorable than that of its CNT and N‐CNT counterparts.This work provides a novel method to fabricate high‐performance fuel cell electrocatalysts with highly dispersed and stable Pt‐based nanoparticles on a carbon substrate.

Elastic-energy imaging condition based on energy-flow vector

Elastic reverse-time migration can effectively deal with multicomponent seismic data in which the imaging condition based on energy norm can extract the scalar-imaging result from multicomponent data.However,the energy cross-correlation imaging condition characterized by particle velocity and stress suffers from the problem of overdependence on the background elastic parameters.Therefore,we characterize the elastic-wave energy using the energy-flow vector,which is equal to the energy density,without background elastic parameters.According to the source and receiver wave fields,we propose an imaging energyflow vector and an elastic-wave energy imaging condition.Under the assumption of a planewave solution,the backscattering suppression is verified.The numerical simulations show that the elastic-energy imaging condition can obtain the energy image without backscattering.Compared with the cross-correlation imaging conditions in a vector-based wave field,the proposed imaging condition can eliminate the dependence on the background elastic parameters and effectively process seabed multicomponent data,which are conducive to further providing an interpretation of marine geological structures.

Design and Selection of High Energy Materials based on 4,8-Dihydrodifurazano[3,4-b,e]pyrazine

In order to search for high energy density materials,various 4,8-dihydrodifurazano[3,4-b,e]pyrazine based energetic materials were designed.Density functional theory was employed to investigate the relationships between the structures and properties.The calculated results indicated that the properties of these designed compounds were influenced by the energetic groups and heterocyclic substituents.The-N3 energetic group was found to be the most effective substituent to improve the heats of formation of the designed compounds while the tetrazole ring/-C(NO_(2))_(3) group contributed much to the values of detonation properties.The analysis of bond orders and bond dissociation energies showed that the addition of-NHNH2,-NHNO_(2),-CH(NO_(2))_(3) and-C(NO_(2))_(3) groups would decrease the bond dissociation energies remarkably.Compounds A8,B8,C8,D8,E8,and F8 were finally screened as the potential candidates for high energy density materials since these compounds possess excellent detonation properties and acceptable thermal stabilities.Additionally,the electronic structures of the screened compounds were calculated.

Rhizoma polygonati from Mount Tai:nutritional value and usefulness as a traditional Chinese medicine,source of herbzyme,and potential remediating agent for COVID-19 and chronic and hidden hunger

Recently,traditional Chinese medicine-based treatment has succeeded in fighting coronavirus disease 2019(COVID-19),and Rhizoma polygonati(Huangjing)has been one of the recommended components.Its processed products play antidiabetic,antiviral,antitumor,antioxidation,antifatigue,antiaging,and immune enhancement roles.The climate in Mount Tai is mild,and the dense forest is suitable for the growth of Rhizome polygonati,which has gradually evolved into a unique specie.Considering the important medicinal value and pleasant taste of Mount Tai-Rhizoma polygonati,various healthy and functional food products,controlled by quality markers with anti-COVID-19 potential,as well as emergency foods can be developed.The study aimed to review current evidence on the nutritional value of Rhizoma polygonati from Mount Tai and its usefulness as a traditional Chinese medicine,source of herbzyme,and potential remediating agent for COVID-19 and food shortage.Most recent findings regarding herbal nanomedicine have revealed that nanoscale chemical compounds are potentially efficient in drug delivery or nanozyme catalysis upon bioprocessing.Nanoflower structure is found in processed Rhizoma polygonati by self-assembly and has wide application in enzymatic events,particularly nanoscale herbzyme.The novel findings regarding Mount Tai-Rhizoma polygonati could enhance its novel applications in chronic and hidden hunger,clinical nanomedicine,and as an anti-COVID-19 agent.

Correlation between mixing enthalpy and structural order in liquid Mg−Si system

The mixing enthalpies and structural order in liquid Mg−Si system were investigated via ab-initio molecular dynamics at 1773 K.By calculating the transferred charges and electron density differences,the dominance of Si−Si interactions in the chemical environments around Si was demonstrated,which determined that the mixing enthalpy reached the minimum on Mg-rich side.In terms of Honeycutt and Anderson(HA)bond pairs based on the partial pair correlation functions,the attraction between Si−Si pairs and Mg atoms was revealed,and the evolution of structural order with Si content was characterized as a process of constituting frame structures by Si−Si pairs that dispersed Mg atoms.Focusing on tetrahedral order of local Si-configurations,a correlation between the mixing enthalpy and structural order was uncovered ultimately,which provided a new perspective combining the energetics with geometry to understand the liquid Mg−Si binary system.

Theoretical Design of Molecular Diode Based on Thiol-and Amino-Terminated Molecules

Utilizing density functional theory(DFT)and non-equilibrium Green's function,we systematically studied the electrical transport and rectification properties of thiol-and amino-terminated molecules embedded in graphene nanoribbons.We firstly found the thiol-terminated moleculesshowbetterelectron transport properties compared to the amino-terminated,which can be attributed to the strong electronwithdrawing ability and favorable coupling effects.Secondly,the symmetrical molecules show almost symmetrical current-voltage(-V)curves and exhibit negligible rectification effects.On the other hand,the asymmetrical molecules exhibit asymmetrical I-V curves and better rectification performance.The rectification effect is closely related to molecular asymmetry degrees.For example,the rectification ratio of asymmetric N6((E)-N1-(3-aminopropyl)-but-2-ene-1,4-diamine)molecule is much smaller than the N4(5-phenylthiazole-2,4-diamine)and N5(2,6-diaminohexane-1,1,5-triol)molecules.Furthermore,we found the rectification ratio of the asymmetrical amino-terminated molecules can reach 400,while the biggest rectification ratio of the thiol-terminated molecule can only reach 45.These findings offer crucial insights for future graphene molecular electronic device design.