It is well-known that data sparsity and cold start are two of the open problems in recommendation system research. Numerous studies have been dedicated to dealing with those two problems. Among these, a method of introducing user context information could effectively solve the problem of data sparsity and improve the accuracy of recommendation algorithms.. The implementation of CO 2 utilization as a raw material for synthesis of fuels and chemicals has potential to reduce CO 2 emissions and close the carbon cycle. Cyclic carbonates, materials used as building blocks for polymers or green solvents in batteries, can be synthesized from CO 2 and alkylene oxides.
