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It is shown that with a small powder layer thickness ( 30 μm ) , a low laser power and a short exposure time ( i.e. , low energy density ) led to development of fine β columnar grains and widespread cell structures whereas increased laser power and exposure time ( i.e. , high energy density ) resulted in pronounced grain growth , increased texture and significantly decreased cell structures .
 material: powder; process parameter: layer thickness; process parameter: laser power; concept or principle: exposure; process parameter: energy density; application: led; machanical property: columnar grains; application: cell; process parameter: laser power; concept or principle: exposure; process parameter: energy density; concept or principle: grain growth; engineering feature: texture; application: cell
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: powder, layer thickness, laser power, exposure, energy density, led, columnar grains, cell, laser power, exposure, energy density, grain growth, texture, cell 
Answer:
 material: powder; process parameter: layer thickness; process parameter: laser power; concept or principle: exposure; process parameter: energy density; application: led; machanical property: columnar grains; application: cell; process parameter: laser power; concept or principle: exposure; process parameter: energy density; concept or principle: grain growth; engineering feature: texture; application: cell