978
The alignment of fibers in 3D printing of composites was one of the major challenges in the reviewed literature and its improvement attracted tremendous research interest in almost all of the existing AM methods .
 material: fibers; manufacturing process: 3D printing; material: composites; concept or principle: research; manufacturing process: AM
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:
 material: fibers; manufacturing process: 3D printing; material: composites; concept or principle: research; manufacturing process: AM