preferential orientation meaning in English

优先定位
择优定向

3 ) in shell of hyriopsis cumingii ( lea ) , the prismatic layers and the nacreous layers are all composed of aragonite minerals , and aragonite crystallites in prismatic layers show obviously preferential orientation of [ 012 ] axis perpendicular to the shell layers , so it is considered that the orientation of aragonite crystallites in prismatic layers perhaps play an important role in deciding the orientation of aragonite crystallites in nacre and acts as one of template to resulting the formation of aragonite with [ 012 ] orientation perpendicular to nacreous layers in nacre
3 )与海水贝壳明显不同的是，三角帆蚌棱柱层矿物相与珍珠层一样皆为文石相，同时查明棱柱层中文石晶体具[ 012 ]轴垂直壳层面的明显的择优取向。本文认为，三角帆蚌棱柱层中文石晶体的择优取向可能对珍珠层中文石晶体的择优取向存在模板导向的作用，导致珍珠层[ 012 ]定向的文石晶体的形成。