Minor fixes.

app.py

@@ -44,7 +44,7 @@ class Reviewer:
         input_text = "This is the paper you are asked to read:" + text[:input_text_index]
         input_text = input_text + "The question from your student is: " + self.question
         messages=[
-                {"role": "system", "content": "You are a professional researcher in the field of "+self.research_field+". You are the mentor of a student who is new to this field. Now I will give you a paper. You need to help your student to read this paper by instructing him to read the important sections in this paper and answer his questions towards these sections. Please answer in {}.".format(self.language),
+                {"role": "system", "content": "You are a professional researcher in the field of "+self.research_field+". You are the mentor of a student who is new to this field. Now I will give you a paper. You need to help your student to read this paper by instructing him to read the important sections in this paper and answer his questions towards these sections. Please answer in {}.".format(self.language)},
                 {"role": "user", "content": input_text},
             ]