A Simulated Test of Algal Influence of Formation and Deposition of Phosphates

This paper deals with a simulated test of biogenic mineralization made with a blue-green alga species,Spirulina platensix. The data in the experiment were recorded by a computerized surveying system. The influ-ence of algae on the accumulation of phosphorus by changing their microenvironment to promote the forma-tion and deposition of phosphate was studied. The results show that the pH value of cultural liquor rose up to 10 and the redox potential (Eh) may dropby 100-200 mV during the algal logarithmic growth stage, and the cultrual liquor was changed into a mediumwith a weakly reducing condition. At the end of the logarithmic growth stage white deposits of Na_2Ca(CO_3)_2·5H_2O and Ca_2Mg (PO_4)_2·2H_2O were formed on the floor of cultural containers. The test presented a wduableevidence for the theory of biogenic mineralization.

Using the DEM-CFD method to predict Brownian particle deposition in a constricted tube

Modelling of the agglomeration and deposition on a constricted tube collector of colloidal size particles immersed in a liquid is investigated using the discrete element method （DEM）. The ability of this method to represent surface interactions allows the simulation of agglomeration and deposition at the particle scale. The numerical model adopts a mechanistic approach to represent the forces involved in colloidal suspensions by including near-wall drag retardation, surface interaction and Brownian forces. The model is implemented using the commercially available DEM package EDEM 2.3~, so that results can be repli- cated in a standard and user-friendly framework. The effects of various particle-to-collector size ratios, inlet fluid flow-rates and particle concentrations are examined and it is found that deposition efficiency is strongly dependent on the inter-relation of these parameters. Particle deposition and re-suspension mechanisms have been identified and analyzed thanks to EDEM＇s post processing capability. One-way coupling with computational fluid dynamics （CFD） is considered and results are compared with a two- way coupling between EDEM 2.3 and FLUENT 12.1. It is found that two-way coupling requires circa 500% more time than one-way coupling for similar results.

Experimental-computational study of fibrous particle transport and deposition in a bifurcating lung model

Experiments carried out using a lung model with a single horizontal bifurcation under different steady inhalation conditions explored the orientation of depositing carbon fibers, and particle deposition frac- tions. The orientations of deposited fibers were obtained from micrographs. Specifically, the effects of the sedimentation parameter （γ）, fiber length, and flow rate on orientations were analyzed. Our results indicate that gravitational effect on deposition cannot be neglected for 0.0228 〈 γ 〈 0.247. The absolute orientation angle of depositing fibers decreased linearly with increasing y for values 0.0228 〈 γ 〈 0.15. Correspondence between Stokes numbers and y suggests these characteristics can be used to estimate fiber deposition in the lower airways. Computer simulations with sphere-equivalent diameter models for the fibers explored deposition efficiency vs. Stokes number. Using the volume-equivalent diameter model, our experimental data for the horizontal bifurcation were replicated. Results for particle deposition using a lung model with a vertical bifurcation indicate that body position also affects deposition.

Study on the area ratio of Nb–Sn target for the preparation of Nb_(3)Sn films

Introduction Niobium is extremely important in SRF cavities because of its superconducting properties.However,there are some intrinsic limits of Nb cavities that cannot meet the requirements of future accelerators.It is therefore of utmost importance to look into materials offering SRF performances beyond niobium.Nb3Sn is the most promising material.In our work,the cathode target is cylindrical and rotatable,containing both Nb and Sn elements,which are simultaneously charged,aiming to explore the area ratios of the two elements required in the cathode target by simulation and experiments,respectively.This work will provide the basis for the subsequent Nb3Sn cathode target fabrication.Simulations and experiments In the simulation,we calculated stoichiometric ratio and sputtering yield to obtain the area ratios of Nb and Sn.In the experiment,we calculated the rotation rate of the target,deposition thickness of films on substrates and deposition rate to obtain the area ratio of Nb and Sn.Conclusion In conclusion,we compared the simulation and experimental results and found that they are in good agreement.The simulation and experimental results also showed that the area ratio of Nb to Sn in the target is close to 9:1.These results lay the foundation for the subsequent Nb3Sn cathode target fabrication and multilayer deposition of Nb3Sn thin films.