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Some of the challenges presented by high viscosity materials , for instance , difficulties in mixing and changing inks to create devices from more than one type of silicone , could be overcome by use of lower viscosity inks .
 machanical property: viscosity; concept or principle: materials; concept or principle: mixing; material: silicone; material: be; machanical property: viscosity
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: viscosity, materials, mixing, silicone, be, viscosity 
Answer:
 machanical property: viscosity; concept or principle: materials; concept or principle: mixing; material: silicone; material: be; machanical property: viscosity