Technical/scientific PDFs generally do not survive well the process of converting them from PDF to another format. I'd advise either tweaking the PDFs or converting them to images and working with the images to make them better work on your screen size.
Try tools like
soPDF ,
PDFLRF and/or
PaperCrop to see if any of them yield something that you can read comfortably.
I use these tools to read technical PDFs on my Sony PRS-505, which has a much smaller screen than a Daily Edition or DX.