spotlight can not find certain files?
I am trying to locate a pdf file (the pdf can be downloaded from https://www.frontiersin.org/articles/10.3389/fphys.2019.00094/full) with the following command.
```
mdfind -onlyin . "(kMDItemTextContent=='oxidative stress'c) && (kMDItemFSName=='*.pdf')"
```
But I don't find it. The file is in the spotlight database. The output of the following command is attached. The field kMDItemTextContent does contain "oxidative stress". Does anybody know why spotlight can not find it? Thanks.
```
mdimport -d2 30814954.pdf
```
MacBook Air 13", macOS 10.14