Blockchain is a disruptive technology that will revolutionize the Internet and our way of living, working, and trading. However, the consensus protocols of most blockchain-based public systems show vulnerabilities and performance limitations that hinder the mass adoption of blockchain. This paper presents and compares the main proof-based consensus protocols, focusing on the security and performance of each consensus protocol. Proof-based protocols use the probabilistic consensus model and are more suitable for public environments with many participants, such as the Internet of Things (IoT). We highlight the centralization tendency and the main vulnerabilities of Proof of Work (PoW), Proof of Stake (PoS), and their countermeasures. We also analyze and compare alternative proof-based protocols, such as Proof of Elapsed Time (PoET), Proof of Burn (PoB), Proof of Authority (PoA), and Delegated Proof of Stake (DPoS). Finally, we analyze the security of the IOTA consensus protocol, a DAG-based platform suited for the IoT environment.
Keywords Blockchain • Consensus • Security1 Satoshi Nakamoto is a pseudonym used by the creator or creators of the Bitcoin cryptocurrency. The real identity is unknown. 2 The network nodes are identified by an asymmetric key pair, that provides a some level of anonymity. However, curious nodes can infer identity information based on blockchain history.
Microorganisms are a source of many high-value compounds which are useful to every living being, such as humans, plants and animals. Since the process of isolating and improving a microorganism can be lengthy and expensive, preserving the obtained characteristic is of paramount importance, so the process does not need to be repeated. Fungi are eukaryotic, achlorophyllous, heterotrophic organisms, usually filamentous, absorb their food, can be either macro or microscopic, propagate themselves by means of spores and store glycogen as a source of storage. Fungi, while infesting food, may produce toxic substances such as mycotoxins. The great genetic diversity of the Kingdom Fungi renders the preservation of fungal cultures for many years relevant. Several international reference mycological culture collections are maintained in many countries. The methodologies that are most fit for preserving microorganisms for extended periods are based on lowering the metabolism until it reaches a stage of artificial dormancy. The goal of this study was to analyze three methods for potentially toxigenic fungal conservation (Castellani’s, continuous subculture and lyophilization) and to identify the best among them.
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