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At present , there are no design guidelines on material compatibility , mixing range for materials with variable and non-uniform properties and a framework for optimal property distribution such as choice of spatial , gradient distribution and the arrangement of transition phases is also lacking .
 engineering feature: design; material: material; concept or principle: mixing; concept or principle: materials; concept or principle: properties; concept or principle: framework; concept or principle: property; concept or principle: distribution; material: as; concept or principle: distribution; concept or principle: transition phases
Please list all entity words in the text that fit the category.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} 
Answer:
 engineering feature: design; material: material; concept or principle: mixing; concept or principle: materials; concept or principle: properties; concept or principle: framework; concept or principle: property; concept or principle: distribution; material: as; concept or principle: distribution; concept or principle: transition phases