Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan.
J Chem Phys. 2010 Oct 21;133(15):154705. doi: 10.1063/1.3481650.
In this paper, nonequilibrium molecular dynamics simulations were performed on a single component 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine lipid bilayer in order to investigate the thermal conductivity and its anisotropy. To evaluate the thermal conductivity, we applied a constant heat flux to the lipid bilayer along and across the membrane with ambient water. The contribution of molecular interaction to the heat conduction was also evaluated. Along the bilayer plane, there is little transfer of thermal energy by the interaction between lipid molecules as compared with the interaction between water molecules. Across the bilayer plane, the local thermal conductivity depends on the constituents (i.e., water, head group, and tail group of lipid molecule) that occupy the domain. Although the intramolecular transfer of thermal energy in the tail groups of lipid molecules works efficiently to promote high local thermal conductivity in this region, the highest thermal resistance appears at the center of lipid bilayer where acyl chains of lipid molecules face each other due to a loss of covalent-bond and low number density. The overall thermal conductivities of the lipid bilayer in the directions parallel and perpendicular to the lipid membrane have been compared, and it was found that the thermal conductivity normal to the membrane is higher than that along the membrane, but it is still smaller than that of bulk water.
本文通过对单一组分 1,2-二月桂酰-sn-甘油-3-磷酸胆碱脂质双层进行非平衡分子动力学模拟，研究了其热导率及其各向异性。为了评估热导率，我们在环境水中沿膜和穿过膜向脂质双层施加恒定热通量。还评估了分子相互作用对热传导的贡献。与水分子相互作用相比，在双层平面内，脂质分子相互作用对热能量的传递贡献很小。在双层平面内，局部热导率取决于占据该区域的组分（即水分子、脂质分子的头基和尾基）。尽管脂质分子尾基团内的热能分子转移有效地促进了该区域的局部高导热率，但由于共价键的损失和低数密度，在脂质双层的中心出现了最大的热阻，因为脂质分子的酰基链彼此相对。比较了平行于和垂直于脂质膜方向的脂质双层的总热导率，发现垂直于膜的热导率高于沿膜的热导率，但仍小于体相水的热导率。
