I have been rejected under section 212(a)(3)(A)(i). What can I do now? I won't be able to enter US anymore or apply to F2 visa?

I have been rejected (F1 Visa for PhD studies) under section 212 (a)(3)(a)(i) recently after seven months waiting. I had obtained J-1 visa two years ago. My supervisor had written a research plan for me and he directly had mentioned that my research is related to basic science and I am not be dealing with any export-controlled technology tasks and ... My PhD research topic is not mentioned obviously at Technology alert list (TAL). I would like to know why I have been rejected and If I apply again how much is my chance of getting visa?