I read mostly non-fiction. I am not very interested in many non-fiction books published before 2000. Is there any way to search by topic and also weed out the older books? For example, could I find all the books published on Russia or nuclear energy within the last 7 years easily? TIA

You can do a search by topic.  I would start with "Russia", then "nuclear energy".  To weed out books you are interested in, there is a new "tag" feature that has just been put into use.  Where the information shows for "Order this Book", look down and you will see this new, little tag box.  You can then create a tag and put all the listings you are interested in pursuing under this tag.  Brand new, I hope you find it will help you out.

You could also go into advanced search. Put in the genre or key words, published date and greater than, then tell it to search posted books.