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On-demand electrospray ionization from different liquid channels in the same emitter was realized using filamented capillary and gas phase charge supply. The solution sub-channel was formed when back-filling solution to the emitter tip by capillary action along the filament. Gas phase charge carriers were used to trigger electrospray ionization from the solution meniscus at the tip. The meniscus at the tip opening may be fully filled or partially empty to generate electrospray ionization in main-channel regime and sub-channel regime, respectively. For emitters with 4 μm tip opening, the two nested electrospray (nested-ESI) channels accommodated ESI flow rates ranging from 50 pL min−1 to 150 nL min−1. The platform enabled on-demand regime alternations within one sample run, in which the sub-channel regime generated smaller charged droplets. Ionization efficiencies for saccharides, glycopeptide, and proteins were enhanced in the sub-channel regime. Non-specific salt adducts were reduced and identified by regime alternation. Surprisingly, the sub-channel regime produced more uniform responses for a peptide mixture whose relative ionization efficiencies were insensitive to ESI conditions in previous picoelectrospray study. The nested channels also allowed effective washing of emitter tip for multiple sampling and analysis operations., Nested electrospray ionization alternates on-demand between microscale main-channel and nanscale sub-channels.

Zirconium disilicide (ZrSi2) has been investigated experimentally and theoretically for its structural and physical properties at high pressures. In situ compression experiments demonstrate that at...

The Vickers hardness of the bulk TaB and nano-TaC ceramics sintered at high pressure and high temperature were measured by using a diamond indentation method. Our tests gave a maximum Vickers hardness of 13.9 GPa for TaB, and 19.2 GPa for nano-TaC ceramics under a load of 29.4 N. The hardness of nano-TaC-5 wt% Co composites was also measured under the same load for comparison, which was found to be much lower than that of TaB and nano-TaC. The relative densities calculated by the Archimedes method are 13.5 g/cm3 for TaB and 13.6 g/cm3 for nano-TaC. The averaged fracture toughness is 6.8 ± 0.3 MPa m1/2 for TaB and 5.0 ± 0.2 MPa m1/2 for nano-TaC. Our results show that the hardness of the TaB may not be as high as previous reports. Keywords: TaB, TaC, High-pressure, Vickers hardness, Fracture toughness

We numerically show the generation of robust vortex clusters embedded in a two-dimensional beam propagating in a dissipative medium described by the generic cubic-quintic complex Ginzburg-Landau equation with an inhomogeneous effective diffusion term, which is asymmetrical in the two transverse directions and periodically modulated in the longitudinal direction. We show the generation of stable optical vortex clusters for different values of the winding number (topological charge) of the input optical beam. We have found that the number of individual vortex solitons that form the robust vortex cluster is equal to the winding number of the input beam. We have obtained the relationships between the amplitudes and oscillation periods of the inhomogeneous effective diffusion and the cubic gain and diffusion (viscosity) parameters, which depict the regions of existence and stability of vortex clusters. The obtained results offer a method to form robust vortex clusters embedded in two-dimensional optical beams, and we envisage potential applications in the area of structured light.