A novel privacy protection of permissioned blockchains with conditionally anonymous ring signature

With the rapid development of permissioned blockchains, the problem of privacy leakage within permissioned blockchains is increasingly serious. In this paper, for the privacy problem in permissioned blockchains, a novel privacy protection method has been put forward. In this novel method, the ring signature is used to protect the privacy of the user in permissioned blockchains. On the other hand, the unconditional anonymity of ring signature may be abused maliciously by the adversary. Conditional anonymity is considered to improve the ring signature. Therefore, based on conditionally anonymous ring signature, permissioned blockchains privacy protection scheme has also been laid down. Furthermore, the effects of smart contract for transaction flows are considered. The asynchronous signing transaction process is proposed. The security of the scheme has been formally reduced to the Discrete Logarithm assumption. The comparison with the state-of-the-art and simulation experiment have also demonstrated that the proposed scheme is efficient and practical.

     

青藏高原种子植物区系多样性格局及其影响因素

基于青藏高原6个植物区系种子植物多样性数据,归纳统计得出科属特征、物种组成相似性以及多样性空间分布格局,量化气候、地形和历史因素对植物区系多样性分布格局的影响程度,探究青藏高原不同种子植物区系多样性格局的形成原因。结果表明:(1)青藏高原6个植物区系地区均以草本植物为主(平均68.69%),其中IIIE14横断山脉地区的种子植物种类最为丰富(8786种),而IIIF18西喜马拉雅亚地区的种子植物种类最少(1341种);菊科(12.34%)、杜鹃花属(3.19%)分别是青藏高原植物区系的优势科和优势属。(2)在植物科属水平上,IIIE14地区与IIIE15东喜马拉雅地区相似性系数最高(分别为0.8500、0.7225),IIIE15地区与IIC6喀什噶尔地区相似性系数最低(分别为0.4444、0.2594),而在种水平上,IIIF16唐古特地区与IIC6地区相似性系数最高(0.4673),IIIE14地区与IIIF18地区相似性系数最低(0.0822)。(3)青藏高原植物区系多样性分布格局整体呈现东南多、西北少的局势;气候、地形及历史因素共同决定着青藏高原植物区系多样性格局,其中海拔范围对IIIE14(均值15.49%)、IIIF17(均值25.46%)、IIIF18(均值30.96%)地区、地形异质性对IIIE15地区(均值18.14%)、年均温对IIIF16地区(均值18.04%)、以及年降水量、实际蒸散量对IIC6地区(均值22.94%、24.95%)种子植物物种丰富度和谱系多样性的构建有着重要影响。上述结果表明高原内部不同的环境特点、地质历史和气候变化历史促进了青藏高原植物区系的多样化,形成今日青藏高原差异巨大,但存在一定相似性的独特多样性格局,这为揭示青藏高原不同区域生物多样性的形成和演化提供科学依据。     

茶儿茶素类体内代谢动力学研究进展

儿茶素类作为绿茶的主要成分,具有广泛的生物学行为和药理功能.众多研究表明虽然儿荼素类在体外细胞体系中呈现较强的生物学活性,但其体内与体外表现不尽相同.本文对儿茶素类在生物体内的吸收、分布、代谢产物等进行综述,并对儿荼素类体内研究的前景进行展望,以期为儿荼素类作为药物或辅助药物的开发提供理论依据.     

Studies of cocoa tea, a wild tea tree containing theobromine

Camellia ptilophylla Chang is a wild tea tree containing theobromine and is caffeine-flee. Lots of researches have been conducted for its domestication since it was discovered to contain theobromine in its shoots. First, its pharmacological and physiological effects have been studied, demonstrating that it can be used as a new resource of tea as daily and healthy beverage. Cocoa tea differs from traditional tea in that it does not excite the nervous system. Second, various ways of propagation have been investigated, and sexless cutting has been the method adopted currently. Third, through selection and breeding, plantation of cocoa tea can be set up to cultivate new varieties, and cocoa tea of different flavors such as green cocoa tea, oolong cocoa tea, and black cocoa tea can be processed. Thus, cocoa tea will become a choice in the tea market.