The antifreeze activity of type I antifreeze proteins (AFPIs) is studied on the basis of the statistical mechanics theory, by taking the AFP's adsorption orientation into account. The thermal hysteresis temperatures are calculated by determining the system Gibbs function as well as the AFP molecule coverage rate on the ice-crystal surface. The numerical results for the thermal hysteresis temperatures of AFP9, HPLC-6, and AAAA2kE are obtained for both of the cases with and without inclusion of the adsorption orientation. The results show that the influence of the adsorption orientation on the thermal hysteresis temperature cannot be neglected. The theoretical results are coincidental preferably with the experimental data.

Based on the statistical mechanics model, the coverage rate of the type I antifreeze protein (AFP) on the surface of ice-crystal in a protein solution is studied by including the adsorption orientation, as well as both the AFP–ice and AFP–water hydrophobic interactions. As an example, the computed results for HPLC-6 are given and discussed. It is shown that the coverage rate increases with the AFP concentration for the dilute protein solutions. The effect of the adsorption orientation of AFP molecules on the coverage rate cannot be ignored. Including the adsorption orientation enhances the coverage rate when the AFP solution is very dilute, but reduces it for the slightly thick solution. The stronger the AFP–ice and AFP–water hydrophobic interactions are, the larger the coverage rate is.

This paper presents a new cross-layer QoS routing algorithm for wireless sensor networks. Basing on the principle of cross-layer design, the algorithm adopts delay, nodes’ load and link quality as QoS metrics. The QoS routing metrics are regarded as heuristics correction factors in ant colony algorithm (ACA). The ants are divided into a number of different populations. Through the interaction of pheromone between multi populations, the routing algorithm searches for the feasible paths in parallel and updates the pheromone in time. To overcome the slow convergence of ant colony algorithm, membership cloud model (MCL) is used to control the randomness of the ants. The simulation results demonstrate that the routing algorithm can guarantee the real time, reliability and robustness of wireless sensor networks. It can also achieve the network load balancing.

According to Hill's thermodynamics theory for small system, the effect of small system on the type I antifreeze protein 'HPLC-6' is discussed in this article. We conclude that when the solution is very dilute, the effect is not visible, and as the concentration increases, the effect becomes more visible than before, and the result also shows that the number of molecules on the ice surface becomes larger when the effect of small system is considered.

The AFPs and water molecules are considered together when they adsorb on the ice surface in this article. Based on Myers and Prausnitz’s ideal adsorbed solution theory(IAST) and Langmuir adsorption model, the coverage rate of HPLC-6 on the ice surface is calculated when considering the adsorption of water, and the thermal hysteresis temperature of HPLC-6 is also given. The results show that the thermal hysteresis temperature increases as the concentration increases, and the theoretical result is agreement with experimental data.

Based on the viewpoint that the hydrophobic methyl groups on threonines or valines play the main roles for the binding mechanism of type Ⅰ antifreeze proteins,it has been suggested that the adsorption of antifreeze proteins on the ice crystals is due to van der Waals interactions between these methyl groups and ice crystals,then the interaction energy between a type Ⅰ antifreeze protein and an ice crystal is calculated theoretically,and it also gives the interaction energies of some mutants of a type I antifreeze protein and the ice.The calculation results are in good agreement with the experimental data.

The thermodynamic properties of linear protein solutions are discussed by a statistical mechanics theory with a lattice model. The numerical results show that the Gibbs function of the solution decreases, and the protein chemical potential is enhanced with increase of the protein concentration for dilute solutions. The influences of chain length and temperature on the Gibbs function of the solution as well as the protein chemical potential are analyzed. As an application of the theory, the chemical potentials of some mutants of type I antifreeze proteins are computed and discussed.

A statistical mechanics model is proposed to investigate the thermal hysteresis activity of antifreeze protein. The thermal hysteresis activities are evaluated for AFP9, HPLC-6(TTTT) and AAAA2kE. The results are in agreement with the experimental data.