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SQL injection attacks would cause significant harm because they can steal or destroy data by intruding target database. SQL injection attack detection can find out the potential security threat in time, and it is beneficial to the database security protection. However, in intelligent transportation system, due to its internal complexity and the emergence of new varieties of SQL injection attacks, the size of abnormal samples cannot meet the requirement of machine learning model training. This would carry a significant risk of model overfitting and performance degradation. In order to solve the problem, a SQL injection attack detection framework is designed based on bit coding, considering the characteristics of intelligent transportation systems and SQL injection attacks comprehensively. In the framework, pre training word embedding model and parsing of grammatical rules are not needed. Then, a semi-supervised SQL injection attack detection model (ASDM) is proposed based on this framework, combined with the attention mechanism. In the model, the samples are reconstructed to learn the high-level features (such as the central trend and the dispersion degree of the features) and to express the feature posterior distribution and feature deviation. Then, these high-level features are fused with the data coding features to highlight the differences between different types of data. Finally, the attention mechanism and residual network are introduced to construct the detector, with the aim of exerting different attention intensity to the features according to their importance degree and guaranteeing the generalization ability of the model. The experimental results show that the proposed method has better detection performance compared with other SQL injection attack detection methods for the data with unbalanced labels, and can detect unknown SQL injection attacks. [ABSTRACT FROM AUTHOR]

Silane grafting and water cross-linking of polypropylene (PP) are a recent method to modify its properties, such as melt strength, heat, and chemical resistance. This work aims at grafting silanes onto PP by reactive extrusion. The occurrence of the grafting of silane onto PP was confirmed by Fourier transform infrared (FTIR) and a method based on FTIR was developed to quantify the amount of polymerized silane and that of silane grafted onto PP. The molar mass of the silane-grafted PP and its melt viscosity were also measured. A multi-objective optimization strategy was used to study the effects of processing conditions on the quality of the silane-modified PP. It was concluded that to maximize the amount of silane grafted on PP and minimize the amount of polymerized silane and the decrease in PP chain scission, screw speed and barrel temperature should be low and feed rate high. POLYM. ENG. SCI., 53:1571-1581, 2013. © 2013 Society of Plastics Engineers, INTRODUCTION Cross-linking is an important method for improving properties of polyolefins, such as melt strength, heat, and chemical resistance. A variety of ways can be used to cross-link them, which [...]

Two undescribed disubstituted pyridine derivatives irpexidines A and B (1 and 2) and two undescribed alkylfuran derivatives irpexins K and L (3 and 4) were isolated from fermentation broth of Irpex lacteus. Their structures were established by extensive spectroscopic methods. The pyridine derivatives from this fungus were reported for the first time. The new compounds were evaluated for their cytotoxicity against Hela cancer cell and inhibitory activity on NO production. [ABSTRACT FROM AUTHOR]

Twelve new lanostane triterpenoids (1–5, 7–13) were isolated from the fruiting bodies of the fungus Ganoderma australe. The structures of the new compounds were elucidated by extensive 1D and 2D NMR, and HRESIMS spectroscopic analysis. All the triterpenes are featured by 20(22)E configurations which are uncommon in the Ganoderma triterpene family. The absolute configuration of the C-25 of compounds 1, 2, and 6 were determined by the phenylglycine methyl ester (PGME) method. A postulated biosynthetic pathway for compound 1 was discussed. This study opens new insights into the secondary metabolites of the chemically underinvestigated fungus G. australe. [ABSTRACT FROM AUTHOR]