Russia will tighten security over grain stockpiles following its decision to ban grain exports, which has already caused an 8% price jump and ‘sparked a buying frenzy‘, with many analysts speculating on the likelihood of a world food crisis.  International trading companies contracted to supply Russian wheat to Asian millers suspect that they will be forced to declare force majeure, says Reuters.  President Dmitry Medvedev and his South African counterpart Jacob Zuma met yesterday to discuss deals in metals and nuclear industries and a potential space partnership.  Uranium trader Tenex and Norilsk Nickel have signed agreements, and other deals relate to agricultural trade and visas for diplomats.  Polyus Gold is having trouble paying its bills and wages due to a freeze on its bank accounts, related to a criminal investigation into KazakhGold shareholders.  Is the government’s move to abandon its potash export duty plan ‘a sign of the lobbying power of Ukralkali’s new owners‘?  Vimpelcom hopes to become the first company to launch a Russian Depository Receipt program, ‘the special instrument designed by Russian authorities to attract new companies and investors to the local stock market‘.