Breath volatile biomarkers are capable of distinguishing patients with various cancers.However, high throughput analytical technology is a prerequisite to a large-cohort study intended to discover reliable breath biomarkers for cancer diagnosis. Singlephoton ionization (SPI) is a universal ionization technology, and SPI-mass spectrometry (SPI-MS) shows a remarkable advantage in the comprehensive detection of volatile organic compounds (VOCs), in particular, nonpolar compounds. In this study, we have introduced SPI-MS coupled with on-line thermal desorption (TD-SPI-MS) to demonstrate nontarget analysis of breath VOCs for gastric cancer patients. The breath fingerprints of the gastric cancer patients were significantly distinct from that of the control group. Acetone, isoprene, 1,3-dioxolan-2-one, phenol, meta-xylene,
To strengthen the particles radial
movement and mixing, the longitudinal
vortex generator of a sphere was adopted in the spouted bed in this
study. To find the influence of the longitudinal vortex and particle
properties on axial and radial velocities of particles in a 152 mm-diametered
spouted bed, particle image velocimetry (PIV) was employed. The experimental
results show that the addition of the longitudinal vortex generator
caused the vortex movement of high-speed gas and induced a considerable
secondary fine vortex in the cross section of the spouted bed, and
the existence of longitudinal vortex significantly improved the radial
velocity of particles, compared with that of the conventional spouted
bed. Due to the effect of longitudinal vortex on particles, the phenomenon
of early dropping of particles was increasingly obvious with the rise
in bed height, and the value of axial velocity of particle phase was
negative. With the decrease in the particle diameter, the longitudinal
vortex effect of gas-driven particle movement would be enhanced. The
longitudinal vortex could enhance particle velocity under a wide range
of particle diameters, and the enhancement factor η decreased
with the rise in the particle diameter and gradually approaches to
1.
The swirling flow technology is adopted on a nozzle of the spouted bed in order to enhance the radial movement of the particles. The hydrodynamic characteristics in a spouted bed with a swirling flow generator installed on the nozzle are numerically investigated based on the two-fluid model (TFM). The traditional spouted bed and spouted bed with an integral swirling blade nozzle (ISBN) are simulated and analyzed. Numerical results show that the dead zone at the cone region of the annulus can be effectively eliminated by using the ISBN. The maximum decrease in particle concentration near the cone region is 72%, and the ISBN structure can significantly improve the comprehensive fluidization degree of the spouted bed when γ equals 86°. The turbulent kinetic energy of gas can be significantly increased by the swirling flow along the radial direction in the spouted bed, especially in the spout region. Also, the swirling flow can promote the radial velocity and granular temperature of the particles in the spouted bed, which is helpful to the radial mixing of particles and gas phase between the central spout and the annulus in the spouted bed. There exists a value of ξ (equals 0.526), which brings the greatest elimination effect of the flow dead zone in the annulus of the limited spouted bed space, and the overall fluidization of the spouted bed has the best performance when ξ = 0.316.
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