Binding mechanism of halide ions to bovine serum albumin and hemoglobin: investigated by ion selective-electrode

The binding mechanism of the interactions of halide ions (F–, Br– and I–) with bovine serum albumin (BSA) and hemoglobin (Hb) were studied at different temperatures, by using ion-selective electrodes. The experimental data were treated according to Klotz equation, and the number of binding sites and the binding constants were determined. The results show that the binding sites of F– on protein molecules are more than those of Br– and I–. Additionally, the number of the binding sites for halide ions on protein molecules increases with increasing temperature. This study also indicates that the binding constants for the interactions of halide ions with proteins gradually decrease as the size of halide ions and temperature increases. These behaviors were reasonably interpreted with the structural and thermodynamic factors. The thermodynamic functions at different temperatures were calculated with thermodynamic equations, and the enthalpy change for the interactions were also determined by isothermal titration calorimetry (ITC) at 298.15 K, which indicate that the interactions of halide ions with proteins are mainly electrostatic interaction.

The determining role of carbon addition on mechanical performance of a non-equiatomic high-entropy alloy

The mechanical properties and deformation mechanism of a C-doped interstitial high-entropy alloy(i HEA)with a nominal composition of Fe_(49.5)Mn_(29.7)Co_(9.9)Cr_(9.9)C_(1)(at.%)were investigated.An excellent combination of strength and ductility was obtained by cold rolling and annealing.The structure of the alloy is consisted of FCC matrix and randomly distributed Cr_(23)C_(6).For gaining a better understanding of deformation mechanism,EBSD and TEM were conducted to characterize the microstructure of tensile specimens interrupted at different strains.At low strain(2%),deformation is dominated by dislocations and their partial slip.With the strain increase to 20%,deformation-driven athermal phase transformation and dislocations slip are the main deformation mechanism.While at high strain of 35%before necking,deformation twins have been observed besides the HCP phase.The simultaneous effect of phase transformation(TRIP effect)and mechanical twins(TWIP effect)delay the shrinkage,and improve the tensile strength and plasticity.What's more,compared with the HEA without C addition,the yield strength of the C-doped i HEA has been improved,which can be attributed to the grain refinement strengthening and precipitation hardening.Together with the lattice friction and solid solution strengthening,the theoretical calculated values of yield strength match well with the experimental results.