Strengthened US-Japan Cooperation in the South China Sea in the Context of the“Indo-Pacific Strategy”:Measures,Motivations and Effects

In recent years,the US-Japan alliance has been greatly strengthened,and the South China Sea issue has gradually become an important tool for the two countries to jointly promote the“Indo-Pacific strategy”and attract regional countries to deter China.The US and Japan,in mutual support,have engaged in the South China Sea issue at various levels,in various fi elds and by various means,not only strengthening their military presence in the South China Sea,but also increasing support to the Philippines’provocation against China,which has become important factors for the current heating up of the situation in the South China Sea.

Design of low-alloying and high-performance solid solution-strengthened copper alloys with element substitution for sustainable development

Solid solution-strengthened copper alloys have the advantages of a simple composition and manufacturing process,high mechanical and electrical comprehensive performances,and low cost;thus,they are widely used in high-speed rail contact wires,electronic component connectors,and other devices.Overcoming the contradiction between low alloying and high performance is an important challenge in the development of solid solution-strengthened copper alloys.Taking the typical solid solution-strengthened alloy Cu-4Zn-1Sn as the research object,we proposed using the element In to replace Zn and Sn to achieve low alloying in this work.Two new alloys,Cu-1.5Zn-1Sn-0.4In and Cu-1.5Zn-0.9Sn-0.6In,were designed and prepared.The total weight percentage content of alloying elements decreased by 43%and 41%,respectively,while the product of ultimate tensile strength(UTS)and electrical conductivity(EC)of the annealed state increased by 14%and 15%.After cold rolling with a 90%reduction,the UTS of the two new alloys reached 576 and 627MPa,respectively,the EC was 44.9%IACS and 42.0%IACS,and the product of UTS and EC(UTS×EC)was 97%and 99%higher than that of the annealed state alloy.The dislocations proliferated greatly in cold-rolled alloys,and the strengthening effects of dislocations reached 332 and 356 MPa,respectively,which is the main reason for the considerable improvement in mechanical properties.

A novel immiscible high entropy alloy strengthened via L1_(2)-nanoprecipitate

The low-cost Fe-Cu,Fe-Ni,and Cu-based high-entropy alloys exhibit a widespread utilization prospect.However,these potential applications have been limited by their low strength.In this study,a novel Fe_(31)Cu_(31)Ni_(28)Al_(4)Ti_(3)Co_(3) immiscible high-entropy alloy(HEA)was developed.After vacuum arc melting and copper mold suction casting,this HEA exhibits a unique phase separation microstructure,which consists of striped Cu-rich regions and Fe-rich region.Further magnification of the striped Cu-rich region reveals that it is composed of a Cu-rich dot-like phase and a Fe-rich region.The aging alloy is further strengthened by a L1_(2)-Ni_(3)(AlTi)nanoprecipitates,achieving excellent yield strength(1185 MPa)and uniform ductility(~8.8%).The differential distribution of the L1_(2) nanoprecipitate in the striped Cu-rich region and the external Fe-rich region increased the strength difference between these two regions,which increased the strain gradient and thus improved hetero-deformation induced(HDI)hardening.This work provides a new route to improve the HDI hardening of Fe-Cu alloys.

Microstructure evolution of alumina dispersion strengthened copper alloy deformed under different conditions

Microstructure and texture evolution of Cu-0.23%Al2O3 dispersion strengthened copper alloy, deformed at room temperature or cryogenic temperature, were investigated. The main textures in hot-extruded specimen were Brass {011} 〈211〉 and Cube {100} 〈100〉. Textures of Brass {011} 〈211〉 and Goss {011} 〈100〉 were observed in specimen after deformation at room temperature; while textures of Brass {011} 〈211〉, Goss {011} 〈100〉 and S {123} 〈634〉 were detected after deformation at cryogenic temperature. It is believed that the additional Al2O3 nanoparticles can result in dislocation pinning effect, which can further lead to the suppression of dislocations cross-slip. While in the specimen deformed at cryogenic temperature, both pinning effect and cryogenic temperature are responsible for the formation of Brass, Goss and S textures.

Investigation of the Micro-Mechanics of an Extruded Precipitation-Strengthened Magnesium Alloy under Cyclic Loading

Precipitation strengthening is a crucial microscopic mechanism for enhancing the strength of magnesium alloys. In order to elucidate the influence of precipitation on the microscopic deformation mechanisms and macroscopic mechanical response of magnesium alloys under cyclic loading conditions, we employed a crystal plasticity model to analyze the stress-strain curves, specific crystal plane diffraction intensities, and the temporal evolution of various microscopic deformation mechanisms and twinning volume fractions for an extruded magnesium alloy, AXM10304, containing coherent precipitates. The research findings indicate that precipitation does not fundamentally alter the microscopic mechanisms of this alloy. However, it hinders twinning during the compression stage, mildly promotes detwinning during the tension stage, and enhances tension secondary hardening by elevating the difficulty of activation of the prismatic slip.

High temperature mechanical behavior of alumina dispersion strengthened copper alloy with high content of alumina

The microstructure and its effects on the high temperature mechanical behavior of Cu-2.7%Al_2O_3 （volume fraction） dispersion strengthened copper （ADSC） alloy were investigated. The results indicate that fine alumina particles are uniformly distributed in the copper matrix, while a few coarse ones are distributed on the grain boundaries. Tensile tests results show that Hall-Petch mechanism is the main contribution to the yield strength of ADSC alloy at room temperature. Its high temperature strength is attributed to the strong pinning effects of alumina particles on the grain and sub-grain boundaries with dislocations. The ultimate tensile strength can reach 237 MPa and the corresponding yield strength reaches 226 MPa at 700℃. Tensile fracture morphology indicates that the ADSC alloy shows brittleness at elevated temperatures. Creep tests results demonstrate that the steady state creep rates at 400 ℃ are lower than those at 700 ℃. The stress exponents at 400 ℃ and 700℃ are 7 and 5, respectively, and the creep strain rates of the ADSC alloy are controlled by dislocation core diffusion and lattice diffusion.

Experimental study on aseismic behaviors of Chinese ancient tenon-mortise joint strengthened by CFRP

In order to well protect Chinese ancient buildings, aseismic behaviors of Chinese ancient tenon-mortise joints strengthened by carbon fibre reinforced plastic （CFRP） are studied by experiments. Based on the actual size of an ancient building, a wooden frame model with a scale of 1 ： 8 of the prototype structure is built considering the swallow-tail type of tenon-mortise connections. Low cyclic reversed loading tests are carried out including three groups of unstrengthened structures and two groups of structures strengthened with CFRP. Based on experimental data, moment-rotation angle hysteretic curves and skeleton curves for each joint are obtained. The energy dissipation capability, stiffness degradation and deformation performance of the joints before and after being strengthened are also analyzed. Results show that after being strengthened with CFRP, the tenon value pulled out of the mortise is reduced; the bending strength and the energy dissipation capabilities of the joint are enhanced; stiffness degradation of the joint is not obvious; and the deformation performance of the joint remains good. Thus, the CFRP has good effects on strengthening the tenon-mortise joints of Chinese ancient buildings.

Fatigue behavior of crane beam strengthened with CFRP

In order to study the fatigue behavior of the damaged reinforced concrete （RC） beams strengthened by carbon fiber reinforced polymer （CFRP） laminate, three T-shaped beams strengthened by CFRP and one contrasting beam are tested under fatigue loading, with the parameters of different modes of strengthening and different fatigue load levels considered. The main results obtained from the tests are： the width of the crack decreases 50. 2% to 66%, and the development of the crack is limited; the stress of steel decreases 24. 1% to 28. 2%, and the stiffness increases 14.9% to 16. 1% after being strengthened. Based on the technical specification for strengthening concrete structures with CFRP and the conclusions from the tests, a calculating scheme of the flexure stiffness is given, which can be used for reference in engineering design. Finally, some suggestions are given for design in fatigue strengthening.

Flexural behaviors of FRP strengthened corroded RC beams

The flexural behavior of eight FRP （ fiber reinforced polymer） strengthened RC （reinforced concrete） beams with different steel corrosion rates are numerically studied by Ansys finite element software. The influences of the corrosion rate on crack pattern, failure mechanism, ultimate strength, ductility and deformation capacity are also analyzed. Modeling results show that the beams with low corrosion rates fail by the crushing of the concrete in the compression zone. For the beams with medium corrosion rates, the bond slip between the concrete and the longitudinal reinforcement occurs after steel yielding, and the beams finally fail by the debonding of the FRP plates. For the beams with high corrosion rates, the bond slip occurs before steel yielding, and the beams finally fail by the crushing of the concrete in the compression zone. The higher the corrosion rates of the longitudinal reinforcement, the more the carrying capacity of FRP strengthened RC beams reduces. The carrying capacity of RCB-1 （the corrosion rate is 0） is 115 kN, and the carrying capacity of RCB-7 （the corrosion rate is 20% ） is 42 kN. The deformation capacity of FRP strengthened corroded RC beams is higher than that of FRP strengthened uucorroded RC beams. The ultimate deflection of RCB-1 and RCB-7 are 20 mm and 35 nun, respectively, and the ultimate deflection of RCB-5 （the corrosion rate is 10% ） reaches 60 ilUn.

Strengthened Monitoring of H5 Avian Influenza Viruses in External Environment in Hubei, 2018

The contamination status of H5 avian influenza viruses and distribution of subtypes of H5N1 and H5N6 in poultry-related environment of Hubei areas were investigated.Urban and rural live poultry markets,poultry farms,intensive livestock farms and other monitoring types of 103 counties in 17 cities were selected in Hubei.Wiping samples from cage surface,wiping samples from chopping board,fecal specimens and other environmental samples were collected and tested by real-time RT-PCR using primers and probes of influenza A,avian influenza of H5,N1 and N6 from December 2017 to March 2018.The avian influenza virus positive rate was compared among different monitoring sites,samples,time and regions.Totally,7132 environmental samples were collected in 1634 monitoring points with a positive rate of 2.24%.The positive rate of H5 avian influenza virus was the highest in urban and rural live poultry markets(3.44%,x^2=61.329,P<0.05)in 6 monitoring sites and wiping samples from chopping board(5.46%,x^2=67.072,P<0.05)in 6 sample types.H5N6 avian influenza viruses were detected more in eastern than western Hubei,and H5N6 avian influenza viruses were detected only in Xiangyang city of western Hubei.There were important high-risk places of human infection with H5 avian influenza virus in urban and rural live poultry markets and the poultry slaughtering plants.H5N6 has been the predominant subtype of H5 avian influenza viruses in the eastern and western Hubei and H5N6 avian influenza viruses were still present in a few areas of Hubei.Outbreaks of human H5N1 and H5N6 avian influenza remain at risk in Hubei province.

Microstructural Features and Properties of High-hardness and Heat-resistant Dispersion Strengthened Copper by Reaction Milling

The oxide dispersion strengthened copper alloys are attractive due to their excellent combination of thermal and electrical conductivities,high-temperature strength and microstructure stability.To date,the state-of-art to fabrication of them was the internal oxidation （IO） process.In this paper,alumina dispersion strengthened copper （ADSC） powders of nominal composition of Cu-2.5 vol%Al2O3 were produced by reaction milling （RM） process which was an in-situ gas-solid reaction process.The bulk ADSC alloys for electrical and mechanical properties investigation were obtained by sintering and thereafter hot extrusion.After the hot consolidation processes,the fully densified powder compacts can be obtained.The single γ-Al2O3 phase and profile broaden effects are evident in accordance with the results of X-ray diffraction （XRD）;the HRB hardness of the ADSC can be as high as 95;the outcomes should be attributed to the pinning effect of nano γ-Al2O3 on dislocations and grain boundaries in the copper matrix.The electrical conductivity of the ADSC alloy is 55%IACS （International Annealing Copper Standard）.The room temperature hardness of the hot consolidated material was approximately maintained after annealing for 1 h at 900 ℃ in hydrogen atmosphere.In terms of the above merits,the RM process to fabricating ADSC alloys is a promising method to improve heat resistance,hardness,electrical conductivity and wear resistance properties etc.

Stress-rupture measurements of cast magnesium strengthened by in-situ production of ceramic particles

We have introduced a polymer precursor into molten magnesium and then in-situ pyrolyzed to produce castings of metal matrix composites(P-MMCs)containing silicon-carbonitride(SiCNO)ceramic particles.Stress-rupture measurements of as-cast P-MMCs was performed at 350 ℃(0.69TM)to 450 ℃(0.78TM)under dead load condition corresponding to tensile stress of 2.5 MPa to 20 MPa.The time-to-fracture data were analyzed using the classical Monkman–Grant equation.The time-to-fracture is thermally activated and follows a power-law stress exponent exhibiting dislocation creep.Fractography analysis revealed that while pure magnesium appears to fracture by dislocation slip,the P-MMCs fail from the nucleation and growth of voids at the grain boundaries.

Influence of nano-scaled dispersed second phase on substructure of deformed dispersion strengthened copper alloy

The deformation behavior of dispersion strengthened copper alloy Cu-Al2O3 was studied by TEM. The results show that nano-scaled dispersed second phase not only increases dislocation density in matrix, but also has an important influence on the dislocation substructure. The presence of fine dispersed Al2 O3 particles results in a uniform and random dislocation distribution in matrix copper and causes the difficulty in formation of dislocation cell structure and the decrease in the amount of cell structure during deformation. Deformation gives rise to much more dislocations and dislocation cells form more difficultly and the decrease in the cell size with the increase of dispersion degree.

Fifteen-year mortality and prognostic factors in patients with dilated cardiomyopathy:persistent standardized application of drug therapy and strengthened management may bring about encouraging change in an aging society

BACKGROUND There is scarce data on the long-term mortality and associated prognostic factors in patients with dilated car-diomyopathy(DCM).The study aimed to investigate the all-cause mortality up to 15 years(mean 7.9±5.7 years)in such patients,and the independent prognostic factors influencing their long-term mortality.METHODS One hundred and sixty-six consecutive patients with DCM were prospectively enrolled from 2002 to 2003.The mean age of patients was 59.5±10.4 years,and approximately 57%were male.They were followed up by telephone or outpa-tient visit at least every three months until 2019 or all-cause death occurred.Predictors of mortality were identified using mul-tivariate logistic regression analysis.RESULTS During the 15 years of follow-up,five patients were lost to follow-up,and the complete data records of 161 patients were included in the analysis.Patients were treated with angiotensin-converting-enzyme inhibitors(ACEI)or angiotensin-recept-or blocker(ARB),β-blockers,mineralocorticoid receptor antagonist(MRA),diuretics and digitalis from 2002 to 2004,and main-tained at the maximum tolerated doses between 2004 and 2019.Our safety targets to maintain heart rate and blood pressure at 60-80 beats/min and 90-120/60-80 mmHg,respectively.All-cause mortality in the first five years was 55.9%.The independent risk factors for the 5-year mortality were age≥70 years old(OR=5.45,P=0.006),systolic blood pressure(SBP)>120 mmHg(OR=3.63,P=0.004),6-minute walk distance(6MWD)<450 m(OR=3.84,P=0.001).15-year all-cause mortality was 65.8%.The inde-pendent risk factors for 15-year mortality were age≥70 years old(OR=16.07,P=0.009),LVEF≤35%(OR=5.69,P=0.003),and SBP>120 mmHg(OR=9.56,P<0.001).CONCLUSIONS This study was the first to demonstrate the 15-year survival rate of 34%in DCM patients.The DCM patients’first five-year all-cause mortality decreased significantly after continuous standardized treatment and intensive management.The mortality then plateaued in the following 10 years.Age≥70 years,LVEF≤35%,and SBP>120 mmHg were independent predict-ors of 15-year all-cause mortality.

Research progress on preparation technology of oxide dispersion strengthened steel for nuclear energy

Nuclear energy is a low-carbon,safe,efficient,and sustainable clean energy.The new generation of nuclear energy systems operate in harsher environments under higher working temperatures and irradiation doses,while traditional nuclear power materials cannot meet the requirements.The development of high-performance nuclear power materials is a key factor for promoting the development of nuclear energy.Oxide dispersion strengthened(ODS)steel contains a high number density of dispersed nano-oxides and defect sinks and exhibits excellent high temperature creep performance and irradiation swelling resistance.Therefore,ODS steel has been considered as one of the most promising candidate materials for fourth-generation nuclear fission reactor cladding tubes and nuclear fusion reactor blankets.The preparation process significantly influences microstructure of ODS steel.This paper reviews the development and perspective of several preparation processes of ODS steel,including the powder metallurgy process,improved powder metallurgy process,liquid metal forming process,hybrid process,and additive forging.This paper also summarizes and analyzes the relationship between microstructures and the preparation process.After comprehensive consideration,the powder metallurgy process is still the best preparation process for ODS steel.Combining the advantages and disadvantages of the above preparation processes,the trend applied additive forging for extreme manufacturing of large ODS steel components is discussed with the goal of providing a reference for the application and development of ODS steel in nuclear energy.

Discrete dislocation plasticity analysis of dispersion strengthening in oxide dispersion strengthened(ODS) steels

A discrete dislocation plasticity analysis of dispersion strengthening in oxide dispersion strengthened(ODS) steels was described. Parametric dislocation dynamics(PDD) simulation of the interaction between an edge dislocation and randomly distributed spherical dispersoids(Y2O3) in bcc iron was performed for measuring the influence of the dispersoid distribution on the critical resolved shear stress(CRSS). The dispersoid distribution was made using a method mimicking the Ostwald growth mechanism. Then, an edge dislocation was introduced, and was moved under a constant shear stress condition. The CRSS was extracted from the result of dislocation velocity under constant shear stress using the mobility(linear) relationship between the shear stress and the dislocation velocity. The results suggest that the dispersoid distribution gives a significant influence to the CRSS, and the influence of dislocation dipole, which forms just before finishing up the Orowan looping mechanism, is substantial in determining the CRSS, especially for the interaction with small dispersoids. Therefore, the well-known Orowan equation for determining the CRSS cannot give an accurate estimation, because the influence of the dislocation dipole in the process of the Orowan looping mechanism is not accounted for in the equation.

In situ fabrication and properties of Al N dispersion strengthened 2024 aluminum alloy

Nanoscaled aluminum nitride （AlN） dispersion strengthened 2024 aluminum alloy was fabricated using a novel approach in which Al-Mg-Cu compacts were partially nitrided in flowing nitrogen gas. The compacts were subsequently consolidated by sintering and hot extrusion. The microstructure and mechanical properties of the material were preliminarily investigated. Transmission electron microscopy and X-ray diffraction results revealed that AlN particles were generated by the nitridation of Al-Mg-Cu compacts. The material exhibited excellent mechanical properties after hot extrusion and heat treatment. The ultimate tensile and yield strengths of the extruded samples containing 8.92vol% AlN with the T6 heat treatment were 675 and 573 MPa, respectively.

The Researches on Performance and Technology of Strengthened Pure Platinum Wire

This paper discusses about the purity of strengthened pure platinum wire and the development method of platinum micro wire, in order to solve the difficulties of low tensile strength, easy to break, and low rate of micro wire. And it contrasts some performance of strengthened pure platinum wire and sponge Pt wire. The researches draw a conclusion that the thermoelectric properties of strengthened pure platinum micro wire was in accordance with national standards and satisfied users' requirements.

Influence of Y_2O_3 Adding Method on Microstructure and Properties of Al_2O_3 Strengthened Y-TZP

The effects of Y_2O_3 adding methods (i.e.,co-precipitated and mixed) on the microstructure and properties of alumina-strengthened ytrria-stabilized tetragonal zirconia polycrystal (ASZ) were investigated. CYASZ and MYASZ were made by different adding method of Y_2O_3,co-precipitated and mixed,respectively. The results show that CYASZ is of uniform microstructure with fine grain size,however,MYASZ is of inhomogeneous microstructure due to the inhomogeneous distribution of ytrria. Comparing with CYASZ,the density and the strength of MYASZ are decreased,but the toughness is changed only a little. Under sliding wear test,the wear resistance of CYASZ is better than that of MYASZ.

Small-angle neutron scattering study on the stability of oxide nanoparticles in long-term thermally aged 9Cr-oxide dispersion strengthened steel

A 9 Cr-oxide dispersion strengthened(ODS)steel was thermally aged at 873 K for up to 5000 h.The size distribution and chemical composition of the dispersed oxide nanoparticles were analyzed by small-angle neutron scattering under a magnetic field.Combined with transmission electron microscopy,Vickers micro-hardness tests and electron backscattered diffraction measurements,all the results showed that the thermal treatment had little or no effect on the size distributions and volume fractions of the oxide nanoparticles in the ferromagnetic matrix,which suggested excellent thermal stability of the 9 Cr-ODS steel.