Dear Dr Guifeng Liu:

     Recently,I invited you to review the above manuscript, entitled "******" . I have yet to hear from you about this.

     This email is simply a reminder to respond to the invitation to review.  I appreciate your help in accomplishing our goal of having an expedited reviewing process. Please do not hesitate to contact me if I can be of any assistance.

     To respond to the invitation to review, please just click on the link below:

 Agreed:******

Declined:******

 Unavailable:******

      If you agree to review, we would hope to receive your comments on the paper within 60days.

Sincerely,

******

******