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An interesting relationship was demonstrated between dynamic yield stress values and reachable 3D geometries ( the higher σys , the more complex the 3D printed shape can be ) but the study also revealed that it is not the only key factor to ensure the printability of viscoelastic materials when highly complex geometries are seek ; tack and melt strength have also to be investigated .
 concept or principle: dynamic; machanical property: stress; engineering feature: 3D geometries; manufacturing process: 3D printed; material: be; process parameter: printability; machanical property: viscoelastic; concept or principle: materials; concept or principle: complex geometries; machanical property: melt strength; material: be
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: manufacturing standard, machanical property, manufacturing process, material, engineering feature, process parameter, machine or equipment, application, process characterization, enabling technology, biomedical, concept or principle 
Text: {0} 
 Entities: dynamic, stress, 3D geometries, 3D printed, be, printability, viscoelastic, materials, complex geometries, melt strength, be 
Answer:
 concept or principle: dynamic; machanical property: stress; engineering feature: 3D geometries; manufacturing process: 3D printed; material: be; process parameter: printability; machanical property: viscoelastic; concept or principle: materials; concept or principle: complex geometries; machanical property: melt strength; material: be