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In view of the phenomenon that the excavator bucket is damaged before it reaches the theoretical life in the actual normal digging process. Based on the continuous trajectory theory, the three-segment continuous trajectory excavated alternately by bucket and rod is selected as the normal digging trajectory. The theoretical digging force (TDF) and limiting digging force (LDF) on the normal digging trajectory are calculated, compared, and analyzed. The influence of bucket structure strength and modal under two different digging force loads on normal excavation trajectory is analyzed. The constrained mode and free mode analysis of the bucket are carried out, and the modal analysis results are compared with the strength analysis results. The results show that on the selected normal digging trajectory, the LDF considering normal force and resistance moment is generally larger than the TDF, and the influence of the LDF load on the bucket structure strength is also larger. The results provide an explanation for the premature damage of the bucket in the process of normal digging.

Quinolinol derivatives were found to be effective inhibitors of botulinum neurotoxin serotype A (BoNT/ A). Studies of the inhibition and binding of 7-(phenyl(8-quinolinylamino)methyl)-8-quinolinol (QAQ) to the light chain domain (BoNT/A LC) showed that QAQ is a non-competitive inhibitor for the zinc protease activity. Binding and molecular modeling studies reveal that QAQ binds to a hydrophobic pocket near the active site. Its inhibitor effect does not involve the removal of zinc ion from the light chain. A 24-mer SNAP-25 peptide containing E183 to G206 with Q197C mutation (Peptide C) binds to BoNT/A LC with an unusually slow second order binding rate constant of 76.7 M1 s1. QAQ binds to Zn2+-free BoNT/A LC with a KD of 0.67 lM and to Peptide C?BoNT/A LC complex with a KD of 2.33 lM. The insights of the interactions of quinolinols and peptides with the zinc protease of BoNT/A should aid in the development of inhibitors of metalloproteases., The original document contains color images. Pub. in Archieves of Biochemistry and Biophysics, v491, p75-84, 2009.