Drying Technology and Formation Process of Naomai Xingshen Capsules

[Objectives]To optimize the drying technology and formation process of Naomai Xingshen Capsules.[Methods]The yield of paste powder and moisture content as evaluation indicators were taken as indicators,the relative density of feed liquid,inlet air temperature and dosage of excipients were selected as investigation factors,the orthogonal experiment method was used to optimize the spray drying process.The moisture absorption rate and angle of repose were taken as evaluation indicators,the types of forming excipient were screened,and the critical relative humidity was determined.[Results]The optimum spray drying process was that the relative density of liquid medicine was 1.05(60℃),the air inlet temperature was 200℃,and the dosage of excipients was 2%.The effect of using dextrin as a forming excipient was better,and the relative humidity of the production environment should be controlled below 65%.[Conclusions]The optimized process is stable,feasible,scientific and reasonable,and can be used for large-scale industrial production.

Metal-soil interface adhesion in clay clogging during shield tunneling:Theoretical model and experimental validation

Clogging is a major geohazards risk in mechanized tunnelling through cohesive soils.Clay clogging results from the high adhesion between the clay and metal.Based on the water film theory and Reynolds fluid equation,the interfacial adhesion between metal and soil is simplified in this study as viscous hydrodynamic behavior between planes.Considering the influence of capillary force and the viscous force of water film at the interface between metal and soil,a theoretical calculation model of interfacial adhesion between metal and soil is established.The influence of water film thickness and separation rate on the interfacial adhesion between metal and soil is qualitatively analyzed.Then,the adhesion stress between the clay and the metal surface was tested with a pullout test and the influence of moisture content,pullout rates and types of clay minerals on the adhesion stress was analyzed.Finally,the calculation model of adhesion force was compared with the experimental results.The calculation model of soil adhesion stress established in this paper can quantitatively describe the relationship between soil adhesion force and moisture content and can also qualitatively reveal the influence mechanism of soil moisture content on adhesion stress.

Soil conditioning of clay based on interface adhesion mechanism:Microscopic simulation and laboratory experiment

Clogging frequently occurs in the cutter head,excavation chamber or screw conveyor when an earth pressure balance(EPB)shield machine is tunneling in soft or silty clay ground with high clay mineral content.In this paper,montmorillonite,kaolinite,and illite were selected as research objects,and molecular dynamics simulation and laboratory experiment were adopted.At the microscopic scale,dynamic contact behavior and interfacial mechanical behavior of the interface between clay minerals and water/surfactant solution was simulated and the interfacial adhesion and conditioning mechanism between clay minerals and water/surfactant solution was revealed.Thus,sodium dodecyl benzene sulfonate surfactant was selected as the main composition of the soil conditioner.Then,the adhesion stress before and after soil conditioning and the contact angles between clay minerals and water/surfactant solution were tested and analyzed at the macroscopic scale.The result shows that the contact angle between droplet and clay mineral surface is an important parameter to characterize soil adhesion.The simulation rules of the microscopic contact angle are consistent with the experiment results.Furthermore,the adsorption energy between microscopic substances is dominated by electrostatic force,which can reflect the adhesion stress between macroscopic substances.Soil adhesion stress can be effectively decreased by adding the surfactant to the soil conditioner.