Deformation characteristics and strain-compensated constitutive equation for AA5083 aluminum alloy under hot compression

The hot deformation behavior of AA5083 aluminum alloy was studied using isothermal compression tests with a Gleeble 3500 thermal simulator at strain rate of 0.0110 s 1 and at temperature of 300500°C.The experimental results indicate that dynamic recrystallization(DRX)tends to occur at high strain rates and temperatures,and therefore the flow stress is decreased.To predict the flow behavior under different deformation conditions,a strain-compensated constitutive equation based on Arrhenius-type equation and Zener Hollomon parameters was proposed.The flow stresses obtained from the constitutive equation are consistent with the experimental results.The average absolute relative error is only 4.52%over the entire experimental range,indicating that the proposed constitutive equation exhibits high prediction precision for the hot deformation behavior of AA5083 aluminum alloy.

The coupling between hydrodynamic and purification efficiencies of ecological porous spur-dike in field drainage ditch

In this study, a series of ecological porous spur-dikes are arranged in an experiment channel to simulate a real field drainage ditch. The inside and outside flow fields of spur-dikes are determined by numerical simulations and experimental methods. An Ammonia-Nitrogen（NH3-N） degradation evaluation model is built to calculate the pollution removal rate by coupling with the inner flow field of the porous spur-dikes. The variations of the total pollutant removal rate in the channel are discussed in terms of different porosities and gap distances between spur-dikes and inlet flow velocities. It is indicated that a reasonable parameter matching of the porosity and the gap distance with the flow velocity of the ditch can bring about a satisfactory purification efficiency with a small delivery quantity of ecological porous materials.

Modular synthesis of 1,4-diketones through regioselective bis-acylation of olefins by merging NHC and photoredox catalysis

Efficient and modular synthesis of structurally diverse 1,4-diketones from readily available building blocks represents an essential but challenging task in organic chemistry.Herein,we report a multi-component,regioselective bis-acylation of olefins by merging NHC organocatalysis and photoredox catalysis.With this protocol,a broad range of 1,4-diketones could be rapidly assembled using bench-stable feedstock materials.The robustness of this method was further evaluated by sensitivity screening,and good reproductivity was observed.Moreover,the diketone products could be readily converted into functionalized heterocycles,such as multi-substituted furan,pyrrole,and pyridazine.Mechanistic investigations shed light on the NHC and photoredox dual catalytic radical reaction mechanism.