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Lattice structures are advantageous in terms of their high specific stiffness and strength , and have been applied to the design of lightweight structures owing to the recent development of additive manufacturing ( AM ) .
 Lattice structures, specific stiffness, strength, design, lightweight structures, additive manufacturing, AM
Please list all entity words in the text that fit the category. Output format is "word1, 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:
 Lattice structures, specific stiffness, strength, design, lightweight structures, additive manufacturing, AM