Some journals specify that the keywords should not overlap with the title. If your journal has no such specifications, there is no harm in using one or two words or phrases from the title as keywords, especially if those words are really important. In fact, sometimes, using relevant descriptive phrases from the title can help increase your paper's visibility in article searches due to the algorithm used by many search engines. However, make sure that you use other keywords as well as this will include variety and make your work more easily retrievable.

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