DAppSCAN: Building Large-Scale Datasets for Smart Contract Weaknesses in DApp Projects

The Smart Contract Weakness Classification Registry (SWC Registry) is a widely recognized list of smart contract weaknesses specific to the Ethereum platform. Despite the SWC Registry not being updated with new entries since 2020, the sustained development of smart contract analysis tools for detecting SWC-listed weaknesses highlights their ongoing significance in the field. However, evaluating these tools has proven challenging due to the absence of a large, unbiased, real-world dataset. To address this problem, we aim to build a large-scale SWC weakness dataset from real-world DApp projects. We recruited 22 participants and spent 44 person-months analyzing 1,199 open source audit reports from 29 security teams. In total, we identified 9,154 weaknesses and developed two distinct datasets, i.e., DAPPSCAN-SOURCE and DAPPSCAN-BYTECODE. The DAPPSCAN-SOURCE dataset comprises 39,904 Solidity files, featuring 1,618 SWC weaknesses sourced from 682 real-world DApp projects. However, the Solidity files in this dataset may not be directly compilable for further analysis. To facilitate automated analysis, we developed a tool capable of automatically identifying dependency relationships within DApp projects and completing missing public libraries. Using this tool, we created DAPPSCAN-BYTECODE dataset, which consists of 6,665 compiled smart contract with 888 SWC weaknesses. Based on DAPPSCAN-BYTECODE, we conducted an empirical study to evaluate the performance of state-of-the-art smart contract weakness detection tools. The evaluation results revealed sub-par performance for these tools in terms of both effectiveness and success detection rate, indicating that future development should prioritize real-world datasets over simplistic toy contracts.Comment: Dataset available at https://github.com/InPlusLab/DAppSCA

Turn the Rudder: A Beacon of Reentrancy Detection for Smart Contracts on Ethereum

Smart contracts are programs deployed on a blockchain and are immutable once deployed. Reentrancy, one of the most important vulnerabilities in smart contracts, has caused millions of dollars in financial loss. Many reentrancy detection approaches have been proposed. It is necessary to investigate the performance of these approaches to provide useful guidelines for their application. In this work, we conduct a large-scale empirical study on the capability of five well-known or recent reentrancy detection tools such as Mythril and Sailfish. We collect 230,548 verified smart contracts from Etherscan and use detection tools to analyze 139,424 contracts after deduplication, which results in 21,212 contracts with reentrancy issues. Then, we manually examine the defective functions located by the tools in the contracts. From the examination results, we obtain 34 true positive contracts with reentrancy and 21,178 false positive contracts without reentrancy. We also analyze the causes of the true and false positives. Finally, we evaluate the tools based on the two kinds of contracts. The results show that more than 99.8% of the reentrant contracts detected by the tools are false positives with eight types of causes, and the tools can only detect the reentrancy issues caused by call.value(), 58.8% of which can be revealed by the Ethereum's official IDE, Remix. Furthermore, we collect real-world reentrancy attacks reported in the past two years and find that the tools fail to find any issues in the corresponding contracts. Based on the findings, existing works on reentrancy detection appear to have very limited capability, and researchers should turn the rudder to discover and detect new reentrancy patterns except those related to call.value().Comment: Accepted by ICSE 2023. Dataset available at https://github.com/InPlusLab/ReentrancyStudy-Dat

Improved SVD-based data compression method for synchronous phasor measurement in distribution networks

The integration of phasor measurement units (PMUs) greatly improves the operation monitoring level of distribution networks. However, high sampling rates in PMUs generate huge volumes of measurement data, which creates heavy transmission and storage burdens in information and communication systems. In this paper, an improved singular value decomposition (SVD)-based data compression method for PMU measurements in distribution networks is proposed. First, a lossless phase angle conversion method is proposed, which converts the discontinuous phase angle data of PMU into continuous data sequence to enhance the compression performance. Then, a PMU data compression method is proposed based on SVD, and the compression capability is further enhanced by a lossless compression that utilizes the orthogonal property of the two sub-matrices generated by SVD. Moreover, an error control strategy is designed to dynamically optimizes the scale of transmitted data according to the accuracy requirement of different applications in distribution networks. Finally, case studies are performed using real PMU measurement data from a pilot project in China to validate the compression performance and advantages of the proposed method

Preparation and Characterization of Urushiol Methylene Acetal Derivatives with Various Degrees of Unsaturation in Alkyl Side Chain

Preparation of urushiol derivatives was carried out in response to the drug industry’s increasing demand for new synthetic anticancer agents. Urushiol methylene acetal derivatives were synthesized in high yields by reaction of urushiol with methylene chloride under the catalytic action of NaOH. Four kinds of urushiol methylene acetal monomers were separated by silica-gel column and preparative HPLC, and their structures were elucidated by extensive spectroscopic methods, including 1D-NMR and 2D-NMR (1H, 13C-NMR, 1H-1HCOSY, HSQC, and HMBC) as well as TOF-MS. They were identified as 3-[pentadecyl] benzene methylene ether (compound 1), 3-[8′-pentadecatrienyl] benzene methylene ether (compound 2), 3-[8′,11′-pentadecatrienyl] benzene methylene ether (compound 3), and 3-[8′,11′,14′-pentadecatrienyl] benzene methylene ether (compound 4). This research provides a theoretical reference for exploration of these interesting and potentially bioactive compounds

Protective Effect of Akkermansia muciniphila against Immune-Mediated Liver Injury in a Mouse Model

Accumulating evidence indicates that gut microbiota participates in the pathogenesis and progression of liver diseases. The severity of immune-mediated liver injury is associated with different microbial communities. Akkermansia muciniphila can regulate immunologic and metabolic functions. However, little is known about its effects on gut microbiota structure and function. This study investigated the effect of A. muciniphila on immune-mediated liver injury and potential underlying mechanisms. Twenty-two C57BL/6 mice were assigned to three groups (N = 7–8 per group) and continuously administrated A. muciniphila MucT or PBS by oral gavage for 14 days. Mouse feces were collected for gut microbiota analysis on the 15th day, and acute liver injury was induced by Concanavalin A (Con A, 15 mg/kg) injection through the tail vein. Samples (blood, liver, ileum, colon) were assessed for liver injury, systemic inflammation, and intestinal barrier function. We found that oral administration of A. muciniphila decreased serum ALT and AST and alleviated liver histopathological damage induced by Con A. Serum levels of pro-inflammatory cytokines and chemokines (IL-2, IFN-γ, IL-12p40, MCP-1, MIP-1a, MIP-1b) were substantially attenuated. A. muciniphila significantly decreased hepatocellular apoptosis; Bcl-2 expression increased, but Fas and DR5 decreased. Further investigation showed that A. muciniphila enhanced expression of Occludin and Tjp-1 and inhibited CB1 receptor, which strengthened intestinal barriers and reduced systemic LPS level. Fecal 16S rRNA sequence analysis indicated that A. muciniphila increased microbial richness and diversity. The community structure of the Akk group clustered distinctly from that of mice pretreated with PBS. Relative abundance of Firmicutes increased, and Bacteroidetes abundance decreased. Correlation analysis showed that injury-related factors (IL-12p40, IFN-γ, DR5) were negatively associated with specific genera (Ruminococcaceae_UCG_009, Lachnospiraceae_UCG_001, Akkermansia), which were enriched in mice pretreated with A. muciniphila. Our results suggested that A. muciniphila MucT had beneficial effects on immune-mediated liver injury by alleviating inflammation and hepatocellular death. These effects may be driven by the protective profile of the intestinal community induced by the bacteria. The results provide a new perspective on the immune function of gut microbiota in host diseases

Genetic diversity and population structure in Meconopsis quintuplinervia (Papaveraceae)

Meconopsis quintuplinervia is regarded as a valuable medicinal plant in Tibetan medicinal system. This species is distributed in Qinghai, Xizang, Sichuan, Shanxi ,Gansu and Hubei provinces of the People's Republic of China. Genetic variation of 16 M. quintuplinervia populations sampled from Qinghai and Gansu of China was examined by random amplified polymorphic DNA markers (RAPDs). In total, 225 scored DNA bands were amplified from the 17 primers used. Of the 225 loci, 192(85.33%) were polymorphic, and total genetic diversity (Ht) was 0.2954 and Shannon's information index (I) was0.4371, suggesting a relatively high rate of genetic variation at the species level. The average within-population diversity also appeared to be high, with PPB, He and I values of 70.50%, 0.2408 and 0.3347, respectively. Analysis of molecular variance (AMOVA) revealed 78.3% of variation within populations and only 21.7% between populations. Nei's coefficient of differentiation (G ST ) was found to be high (0.2320), also confirming the relatively high level of genetic differentiation within populations. By UPGMA cluster analysis, based on Nei's standard genetic distance, the populations were divided into three groups including the populations distributed in same location together in every group. The results exhibit a strong genetic differentiation which is obviously due to genetic drift in the isolated populations. The genetic structure of M. quintuplinervia has probably been shaped by its breeding modes, biogeographic history and human impact (both grazing and collection for medicinal purposes). This research might be an efficient way to conserve genetic resources of the medicinal plant, in addition to its effective uses

Improving the corrosion resistance of MgZn1.2GdxZr0.18 (x =0, 0.8, 1.4, 2.0) alloys via Gd additions

Funding Information: This research was financially supported by the National Key Research and Development Program of China (Grant No. 2016YFB0301101 ), the National Natural Science Foundation of China (Grant No. 51971054 ) and the Fundamental Research Funds for the Central Universities (Grant Nos. N180904006 and N2009006 ). Publisher Copyright: © 2020 Elsevier LtdEffects of Gd addition on microstructure, corrosion behavior and mechanism of cast and extruded MgZn1.2GdxZr0.18 alloys are investigated through microstructure observation, weight loss and electrochemical tests. Increasing Gd from 0 to 2.0 at.%, grains are refined, MgZn2 phase, W-phase and X-phase are formed successively, and basal texture intensity is decreased. The significantly decreased grain size by extrusion and Gd addition induces formation of protective Gd2O3 and MgO layer. The extruded MgZn1.2Gd2.0Zr0.18 alloy shows decreased corrosion rate of 3.72 ± 0.36 mm/year, owing to fine and homogeneous microstructure, dual-role (micro-anode and barrier) of X-phase, compact oxidation layer and basal crystallographic texture.Peer reviewe