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Femto flow electrospray ionization (ESI) ranging from 240 fL/min to low pico flow (< 10 pL/min) was conducted and measured using submicron emitter tip and relay ESI configuration. Signature analyte ion intensities and profiles were obtained. Obtained flow rate and ionization current enabled size calculation for initial charged nanodroplet.

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.

To study the high-temperature characteristics of bitumen under the influence of freeze-thaw cycles, the results of DSR tests of bitumen and SBS-modified bitumen after 0, 3, 6, 9, 12, 15, and 18 freeze-thaw cycles were investigated. First, based on the simplified model for the DSR tests, the relation between the rheological parameters of the bitumen was analyzed. Then, in combination with the MSCR tests of the SBS-modified bitumen after freeze-thaw cycles, the relation between %R and Jnr was discussed. Finally, FTIR was used to analyze the changes in the chemical composition of the bitumen under freeze-thaw cycles. The results showed that the incorporation of SBS modifiers can increase the elasticity of the bitumen significantly and slow the tendency of the bitumen’s complex shear modulus to increase with the freeze-thaw cycles to a certain extent. The SBS modifiers also can reduce the bitumen’s temperature sensitivity and improve its rutting resistance. After the freeze-thaw cycles, G ∗ / sin δ decreased as temperature increased, and G ∗ sin δ showed an exponential decay with increasing temperature. With an increase in the number of freeze-thaw cycles, G ∗ sin δ of the bitumen and SBS-modified bitumen increased gradually, which indicated that the bitumen’s fatigue resistance weakens gradually after freeze-thaw cycles. The %R0.1 and %R3.2 of SBS-modified bitumen showed a decreasing trend under different stress levels, and the % R 3.2 - % R 0.1 increased, which indicates that bitumen’s high temperature characteristics and temperature fatigue performance show an attenuating trend. The difference between the FTIR spectra of the SBS-modified bitumen fingerprint area after a freeze-thaw cycle was reflected largely in the significant increase in the 1700 cm−1 carbonyl group and 1031 cm−1 sulfoxide group peaks, while the two peaks at 967 cm−1 and 700 cm−1 were relatively stable. These results provide a theoretical basis and technical support for the design, material selection, popularization, and application of an SBS-modified bitumen mixture in roads in regions with seasonal freezing.

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

High temperature stability of asphalt mixture is used to evaluate the performance of asphalt concrete pavement. It is very important for engineers to improve pavement performance by analyzing factors that contribute to high temperature stability for asphalt mixtures. Based on the wheel tracking tests in laboratories, three types of asphalt mixtures with styrene butadiene styrene (SBS) modifier are used to analyze the high temperature performance of asphalt mixtures. It is shown that the optimum contents of SBS modifier would be 5%∼6% in continuous-graded mixtures; Rutting Depth (RD) would reduce and Dynamic Stability (DS) would obviously increase with the increase of SBS modifier; the DS of the coarser asphalt mixtures would be larger than that of the finer mixtures. The coarse aggregate could enhance friction of skeleton structure and mechanical interlocking force among mineral granule so that the shear strength and the high-temperature stability of the hot mixed asphalt mixtures would be significantly improved.

Rutting in asphalt pavement can be influenced by many factors of high-temperature stability of mixture. Taking three continuous-graded and two gap-graded asphalt mixtures as investigation objects, Dynamic Stability (DS) and Rutting Depth (RD) were measured in cases of different temperatures, wheel rolling times and contents of a new anti-rutting agent (ARK-1) by Wheel Tracking Test. The results of testing showed that resistance to rutting of the fine aggregate mixture would be superior to that of the coarse aggregate mixture. No obvious differences between the continuous-graded and gap-graded mixtures could be observed in resistance to rutting as temperature was equal or lower than 60°C. High-temperature stability of the gap-graded or coarse aggregate mixture was better than that of the continuous-graded or fine aggregate mixture as temperature was beyond 60°C. ARK-1 could dramatically improve resistance to rutting of the asphalt mixture. A project example on Baotian freeway between stations 35+460 and 36+460 proves that the costs of pavement made with ARK-1 will be more economical than pavements with SBS-modified binder.