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Analysis of cyanobacterial toxins by hydrophilic interaction liquid chromatography-mass spectrometry 总被引:5,自引:0,他引:5
The combination of hydrophilic interaction liquid chromatography with electrospray mass spectrometry (HILIC-MS) has been investigated as a tool for the analysis of assorted toxins produced by cyanobacteria. Toxins examined included saxitoxin and its various analogues (1-18), anatoxin-a (ATX-a, 19), cylindrospermopsin (CYN, 20), deoxycylindrospermopsin (doCYN, 21), and microcystins-LR (22) and -RR (23). The saxitoxins could be unequivocally detected in one isocratic analysis using a TSK gel Amide-80 column eluted with 65% B, where eluent A is water and B is a 95% acetonitrile/water solution, both containing 2.0 mM ammonium formate and 3.6 mM formic acid. The analysis of ATX-a, CYN and doCYN required 75% B isocratic. Simultaneous determination of 1-21 was also possible by using gradient elution. HILIC proved to be suitable for the analysis of microcystins, but peak shape was not symmetric and it was concluded that these compounds are best analysed using existing reversed-phase methods. The HILIC-MS method was applied to the analysis of field and cultured samples of Anabaena circinalis and Cylindrospermopsis raciborskii. In general, the method proved quite robust with similar results obtained in two different laboratories using different instrumentation. 相似文献
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A new, vectorial approach to fast correlation attacks on binary memoryless combiners is proposed. Instead of individual input sequences or their linear combinations, the new attack is targeting subsets of input sequences as a whole thus exploiting the full correlation between the chosen subset and the output sequence. In particular, the set of all the input sequences can be chosen as the target. The attack is based on a novel iterative probabilistic algorithm which is also applicable to general memoryless combiners over finite fields or finite rings. To illustrate the effectiveness of the introduced approach, experimental results obtained for random balanced combining functions are presentedMost of this work was done while he was with Rome CryptoDesign Center, Gemplus, Italy 相似文献
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The motion of a holonomic scleronomic non-conservative mechanicalsystem with minimal dissipation is considered. As applicationsof the theory several problems are studied in detail. 相似文献
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A Mukherjee M Dasgupta DJ Hinde CR Morton AC Berriman RD Butt JO Newton H Timmers 《Pramana》2001,57(1):195-198
Fusion cross-sections for the 7Li + 12C reaction have been measured at energies above the Coulomb barrier by the direct detection of evaporation residues. The heavy
evaporation residues with energies below 3 MeV could not be separated out from the α-particles in the spectrum and hence their
contribution was estimated using statistical model calculations. The present work indicates that suppression of fusion cross-sections
due to the breakup of 7Li may not be significant for 7Li + 12C reaction at energies around the barrier. 相似文献
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The alternating step generator is a well-known keystream generator consisting of two stop/go clocked LFSRs, LFSR1 and LFSR2, whose clocks are controlled by another LFSR, LFSR3, which is clocked regularly. A probabilistic analysis of this generator is conducted which shows that the posterior probabilites of individual bits of the first derivatives of the regularly clocked LFSR1 and LFSR2 sequences, when conditioned on a given segment of the first derivative of the keystream sequence, can be computed efficiently in a number of probabilistic models of interest. The expected values of these probabilities, for a random keystream sequence, are derived by an approximate theoretical analysis and are also verified by systematic computer experiments. It is pointed out that these posterior probabilities can be enhanced in a resynchronization scenario and thus used for a low-complexity fast correlation attack on the two LFSRs. More generally, it is argued that even without resynchronization these probabilities may be significantly different from one half for fast correlation attacks based on iterative decoding algorithms to be successful, although with incresead complexity. A related method for computing the posterior probabilities of individual bits of the LFSR3 sequence, when conditioned on both the keystream sequence and the LFSR1 and LFSR2 sequences, is also developed. As these posterior probabilities are much more different from one half, they can be used for a low-complexity fast correlation attack on LFSR3, provided that the initial states of LFSR1 and LFSR2 are previously reconstructed. 相似文献