[Simulation research on the movement and deposition of inhalational particles in the human respiratory tract].

An entire 3-dimensional geometry model from mouth, pharynx, larynx, trachea to triple bifurcation and the mathematics models for the calculation of the fluid flow and inhalational particle movement in the respiratory tract were proposed in this paper. The deposition fraction of inhalational particles in the respiratory tract obtained from the numerical simulation was coincident with the experimental data basically. Particles were traced in the Lagrangian frame, and at the same time, particle deposition fraction and position were recorded based on the models. The movement and deposition of the inhalational particles in the upper respiratory tract were analyzed. The results show that the deposition of inhalational particles in different positions have important correlation with the breathing intensity, particle density and particle diameter; deposition fraction of the inhalational particles in the trachea will increase at high breathing intensity and decrease with particle diameter increased; the deposition fraction of the inhalational particles in the larynx is maximal and can attain 35%, but the influence of the breathing intensity and particle diameter on the deposition fraction is smaller relatively; the deposition fraction of the inhalational particles in the triple bifurcation will decrease observably with particle diameter increased; the deposition fraction of the inhalational particles in the triple bifurcation is higher obviously at medium and small breathing intensity compared with that of high breathing intensity. The simulation results of this paper can provide a foundation for the research of the effect of inhalational particles on the human health and the research of the inhaling remedy in medicine.

A field experimental study of lignin sand stabilizing material (LSSM) extracted from spent-liquor of straw pulping paper mills.

A new technique was introduced for sand stabilization and re-vegetation by use of lignin sand stabilizing material (LSSM). LSSM is a reconstructed organic compound with lignin as the most dominant component from the extracts of black-liquor issued by straw pulp paper mills. Unlike the polyvinyl acetate or foamed asphalt commonly used for dune stabilization, the new material is plant-friendly and can be used with virescence actions simultaneously. The field experimental study was conducted since 2001 in China's Northwest Ningxia Hui Autonomous Region and has been proved that LSSM is effective in stabilizing the fugitive dunes, making the arenaceous plants survive and the bare dune vegetative. The advisable solution concentration is 2% and the optimal field spraying quantity is 2.5 L/m2. The soil nutrients of the stabilized and greened dune, such as organic matter, available phosphorous and total nitrogen are all increased compared with the control treatment, which is certainly helpful to the growth of arenaceous plants. The technique is worthwhile to be popularized because it is provided not only a new method for desertification control but also an outlet for cleaning contaminants issued from the straw paper mills.