The findings of this study support the hypothesis that metformin improves the survival for cancer patients with concurrent diabetes, particularly for breast, colorectal, ovarian, and endometrial cancer. Further investigation is warranted.

Nitrogen is an essential element to plants, animals, human beings and all the other living things on earth. Nitrogen fixation, which converts inert atmospheric nitrogen into ammonia or other valuable substances, is a very important part of the nitrogen cycle. The Haber-Bosch process plays the dominant role in the chemical nitrogen fixation as it produces a large amount of ammonia to meet the demand from the agriculture and chemical industries. However, due to the high energy consumption and related environmental concerns, increasing attention is being given to alternative (greener) nitrogen fixation processes. Among different approaches, plasma-assisted nitrogen fixation is one of the most promising methods since it has many advantages over others. These include operating at mild operation conditions, a green environmental profile and suitability for decentralized production. This review covers the research progress in the field of plasma-assisted nitrogen fixation achieved in the past five years. Both the production of NOx and the synthesis of ammonia are included, and discussion on plasma reactors, operation parameters and plasma-catalysts are given. In addition, outlooks and suggestions for future research are also given.

Plasma-assisted nitrogen fixation has been considered a potential green alternative for conventional Haber-Bosch process and has recently received a lot of attention. Ammonia synthesis in nonthermal plasma reactors at atmospheric pressure has been investigated in this research with a 5% Ru/α-Al 2 O 3 catalyst. The operating parameters including feed molar ratio, flow rate, applied voltage, discharge power and argon dilution were investigated to provide information for optimization of NH 3 concentration and energy consumption. Difference between the blank reactor and the catalyst-packed reactor were presented with a discussion on their own optimal parameters. The optimal feed gas ratio (N 2 :H 2 ) for blank reactor and the catalyst-packed reactor are 1:3 and 2:1 correspondingly. Higher flow rate resulted in a lower NH 3 concentration and energy consumption in both blank reactor and the catalyst-packed reactor. Ammonia concentration of 1.49% was achieved in a catalytic DBD reactor with 120 ml min −1 , 2:1 N 2 /H 2 feed gas ratio and 38.4 W discharge power, corresponding to the energy consumption of 32.39 MJ mol −1 . The discharge power and the reactor temperature is important to the synthesis of ammonia in catalytic DBD reactor and the effect of heat build-up in the reactor on NH 3 concentration was observed. Argon addition improved the conversion of nitrogen and hydrogen at a cost of energy consumption and production rate in both blank and catalyst-packed reactor, but it is more beneficial for increasing the conversion of reactants in the case of catalytic DBD reactor.

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