Blockchain Technologies: Probability of Double-Spend Attack on a Proof-of-Stake Consensus.

Two double-spend attack strategies on a proof-of-stake consensus are considered. For each strategy, the probability of its success is obtained, which depends on the network parameters and the number of confirmation blocks. These results can be used to define how many confirmation blocks a vendor should wait after a correspondent transaction before sending goods or services.

New potentialities of HPLC in pharmacopoeian analysis.

Modern status of pharmacopoeian HPLC analysis and its main shortcomings are discussed. The philosophy "special analytical method for each substance" has to be revised, and as an alternative, a principle of creation of universal methods realized by means of HPLC analyzers is proposed. A prototype of such analyzer is described.