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An experimental study is presented on the static behavior of steel plate-masonry composite ( SPMC) columns consisting of irregular masonry columns with steel plates attached to all sides with a combination of steel bolts and epoxy adhesive. Six composite L-shaped and T-shaped specimens were tested. The influence of the bolt-spacing and restraint effect of the bolts were taken into account. The failure process and mode, load-strain curve and bearing capacity of composite columns were elaborated and analyzed. Test results show that the damage of composite columns always starts from the local buckling of steel plates. Critical buckling loads are different between the plates due to the different boundary conditions. The stress redistribution happens as columns approaches the ultimate load. Rather than the rectangular section, the irregular section is remarkably affected by the restraint of the bolts. Cold formed steel plates contribute to the ductility of the specimens. Design equations are given to calculate the compression bearing capacity of such irregular composite columns. [ABSTRACT FROM AUTHOR]

A gas chromatography-mass spectrometric (GC-MS) method has been established for the simultaneous determination of 103 pesticide residues in cabbages and apples using programmable temperature vaporizer-based large volume injection (PTV-LVI) and negative chemical ionization (NCI). It was found that much lower detection limits for the investigated pesticides can be obtained. Prior to GC-NCI/MS analysis, the optimized parameters of PTV-LVI were as follows: inlet temperature was set at 45 degrees C, split vent flow rate was 20 mL/min, evaporation time was 1 min and evaporation temperature was set at 60 degrees C. The volume of injection was 10 microL. Co-extractives were removed from the acetonitrile extracts using solid phase extraction with octadecyl (200 mg) and primary secondary amine (100 mg) sorbents. Matrix matched calibration solutions were used for all the analyses. To evaluate performance of the method, validation experiments were carried out in cabbages and apples at two spiking levels (5 and 10 microg/kg). The average recoveries ranged from 58.5% to 113.2%, and the relative standard deviations (RSDs, n = 6) were in the range of 3.3% - 14.5%. The limits of detection (S/N = 3) were less than 5 microg/kg for all the pesticides. The results show that this method is simple, rapid, sensitive and specific. It is appropriate for the simultaneous identification and quantification of the multi-residues in cabbages and apples.