Effect of multiaxial deformation on structure, mechanical properties, and corrosion resistance of a Mg-Ca alloy

This article provides a report on the effect of multiaxial deformation(MAD) on the structure, texture, mechanical characteristics, and corrosion resistance of the Mg-0.8(wt.)% Ca alloy. MAD was carried out on the alloy in the as-cast and the annealed states in multiple passes, with a stepwise decrease in the deformation temperature from 450 to 250 ℃ in 50 ℃ steps. The cumulative true strain at the end of the process was 22.5. In the case of the as-cast alloy, this resulted in a refined microstructure characterized by an average grain size of 2.7 μm and a fraction of high-angle boundaries(HABs) of 57.6%. The corresponding values for the annealed alloy were 2.1 μm and 68.2%. The predominant mechanism of structure formation was associated with discontinuous and continuous dynamic recrystallization acting in concert. MAD was also shown to lead to the formation of a rather sharp prismatic texture in the as-cast alloy, whilst in the case of the annealed one the texture was weakened. A displacement of the basal poles {00.4} from the periphery to the center of a pole figure was observed. These changes in the microstructure and texture gave rise to a significant improvement of the mechanical characteristics of the alloy. This included an increase of the ultimate tensile strength reaching 308 MPa for annealed material and 264 MPa for the as-cast one in conjunction with a twofold increase in ductility. A further important result of the MAD processing was a reduction of the rate of electrochemical corrosion, as indicated by a significant decrease in the corrosion current density in both microstructural states of the alloy studied.

Some Theoretical and Applied Aspects of the Oceanic Bioluminescence Registration from Space

The analysis of the surface bioluminescence in the World Ocean registration problems for the purposes of its regions ecological express-monitoring and evaluation of the plankton algae spatial distribution at night time by the existing space systems has been proposed. The connection of the plankton community characteristics with a bioluminescent potential (BP) in the euphotic layer and a possibility to evaluate BP according to bioluminescence intensity in the near-surface layer of 0 - 10 m has been demonstrated. It has been shown that with complete correspondence with the vertical structure in the plankton community at the dark time bioluminescence intensity in 0 - 10 m layer exceeds the same in 60 - 70 m layer for one and a half orders and practically determines BP in 0 - 100 m layer. Peculiarities of the plankton organisms light emission, important for the oceanic bioluminescence registration with the space means of observation are under discussion. Equation for calculation of the measured by the space device sea luminescence level and volume of the bioluminescence intensity in the surface layer of theWorldOcean, which can be registered due to modern technical means of the space systems has been corrected. The conclusion has been done that on the base of the space data about spatial and temporal phytoplankton distribution and bioluminescence “in situ” measurements it is possible to create regional algorithms for transition from numerical estimations of the phytoplankton (chlorophyll “a”) to the day time bioluminescent potential and solution of inverse tasks at night time.

沸石催化剂上降冰片烯二聚（英文）

The high activity and selectivity of H‐Beta and H‐ZSM‐12 zeolites in the dimerization of norbornene was established.The norbornene conversion reached 100% in chlorinated paraffin and argon gas medium,with a selectivity of dimer formation of 88%–98%.Four stereo‐isomers of the bis‐2,2'‐norbornylidene structure were identified in the dimer fraction,with the(Z)‐anti‐bis‐2,2'‐norbornylidene prevailing over the others.