The Dynamic Behaviors and Structure Conservation of Protein BMP-2 on Hydroxyapatite Nano Surfaces

The interaction between protein molecules and the hydroxyapatite (HAP) nano surface is an important research topic in many fields. However, the nature of their non-covalent bonding is still not clear at the atomic level. In this work, molecular dynamics (MD) simulation and steered molecular dynamics (SMD) simulation were used to study the adsorption-desorption dynamics of BMP-2 on HAP nano surface. The results suggest that there are two types of adsorption functional groups, –OH and –COO–. And the –COO– group plays the key role. Correspondingly, the Coulombic force between –COO– (in protein BMP-2) and Ca2+ (in the HAP nano particles) is the main adsorption mechanism. As to the conversation for protein BMP-2, it is found that the specific adsorption-desorption behaviors of BMP-2 play a great role in the conversation of the protein. And the conservation may go worse in the regions where the adsorbed residues are located.

Viscosity model for aluminosilicate melt

The structurally based viscosity model proposed in our previous study is extended to include more components, e.g. SiO2, Al2O3, FeO, MnO, MgO, CaO, Na2O and K2O. A simple method is proposed to calculate the numbers of different types of oxygen ions classified by the different cations they bonded with, which is used to characterize the influence of composition on viscosity. When dealing with the aluminosilicate melts containing several basic oxides, the priority order is established for different cations for charge compensating Al3+ ions, according to the coulombic force between cation and oxygen anion. It is indicated that basic oxides have two paradox influences on viscosity: basic oxide with a higher basicity decreases viscosity more greatly by forming weaker non-bridging oxygen bond; while it increases viscosity more greatly by forming stronger bridging oxygen bond in tetrahedron after charge compensating Al3+ ion. The present model can extrapolate its application range to the system without SiO2. Furthermore, it could also give a satisfy interpretation to the abnormal phenomenon that viscosity increases when adding K2O to CaO-Al2O3-SiO2 melt within a certain composition range.

2-D and 3-D Electroconvection, Experiments and Models.

In recent years, a lot of work has been devoted to electrochemical growth without supporting electrolyte1. A model, proposed by one of us2, predicts the existence of a positive space charge and of a large electric field in the active zones of the deposit. This leads to the existence of a coulombic force on the liquid. We show that this coulombic force triggers convective vortices in Hele-Shaw cells3,4, while it triggers vortex rings in three-dimensional cells5.We then couple the electrochemical process to the convective flow and show that, while the border between the depleted and concentrated zones has the shape of an arch in Hele-Shaw cells, it has a toroidal shape in 3-D. When many vortex rings are present, the border between the depleted and the concentrated solution is in the form of domes. We give experimental evidence of the vortex rings. (The original presentation was accompanied by a video movie which can be obtained upon request).