Effects Of Volumetric Flow Rate Research Articles

Nanocluster Budesonide Formulations Enhance Drug Delivery through Endotracheal Tubes

The pulmonary system is an attractive route for drug delivery because the lungs have a large accessible surface area for treatment. For ventilated patients, an endotracheal tube is required for delivering drugs into the lungs. Such tubes are generally poor conduits for delivering traditional aerosol formulations. Both the formulation and the properties of the endotracheal tube are important effectors of delivery efficiency. In this study, agglomerates of budesonide nanoparticles (NanoClusters) were formulated with or without l-leucine or lactose. Teflon tubing was compared with commercial endotracheal tubes as a conduit for delivering budesonide powders into a cascade impactor. The effects of volumetric flow rate, tube size, and humidity were also investigated. NanoCluster budesonide (NC-Bud) formulations had a considerably higher emitted dose and fine particle fraction compared with stock budesonide and the commercial Flexhaler powder when applied through endotracheal tubes. Tubing material did not significantly affect powder performance, but decreasing tubing diameter or increasing volumetric flow rates yielded a smaller mass median aerodynamic diameter for NC-Bud. Engineered NC-Bud powders may dramatically improve drug delivery through endotracheal tubes when using proper ventilator settings.

Mechanical strengths of molten and solidified LLDPE/LDPE blends and wood/LDPE composites under tensile deformation

AbstractThe mechanical strengths of neat low‐density polyethylene (LDPE), a blend of LDPE with linear low‐density polyethylene (LLDPE), and a composite of LDPE with wood flour (wood/LDPE) were investigated in molten and solidified states under tensile deformation. The results are discussed in terms of the effects of LLDPE and wood contents, roller speed, and volumetric flow rate. In LLDPE/LDPE blends, incorporating LLDPE from 0 to 30 wt% into LDPE caused a slight increase in drawdown force, a larger fluctuation in drawdown force, and a reduction of maximum roller speed to failure. The mechanical properties of the solidified LLDPE/LDPE corresponded to those of the molten LLDPE/LDPE with regard to the effect of LLDPE content. For wood/LDPE composites, increasing the wood flour content in molten LDPE caused considerable reductions in drawdown time and maximum roller speed to failure. The drawdown force increased with increasing wood flour up to 10 wt% before it decreased at the wood loading of 20 wt%. A number of voids and pores on the extrudate surfaces became obvious for the composites with 20 wt% of wood content. Increasing wood content enhanced the tensile modulus for the solidified LDPE but decreased its tensile strength. Unlike those of LLDPE/LDPE blends, the changes in tensile modulus and strength of solidified wood/LDPE composites with wood content did not correspond to those of the molten composites. In all cases, the drawdown force increased with increasing roller speed. The effect of volumetric flow rate from the extruder on the mechanical strengths of the solidified blends was more pronounced than on those of the molten ones. J. VINYL ADDIT. TECHNOL., 2011. © 2011 Society of Plastics Engineers

Numerical Simulation of Three Dimensional Extrudate Swell Using Finite Element Method

The precise prediction of extrudate swell is significant to the control of melt flow and the quality of final products. A mathematical model of power law flow for polymer extrusion is investigated. The penalty function formulation is introduced to the finite element model and the free surface is updated with streamline equation in a decoupled method. A proper penalty constant is determined by comparison of numerical results with different penalty constants. The velocity field is obtained and the distribution of velocity on different cross sections is compared. The effects of volumetric flow rate and die shape on extrudate swell ratio are discussed. The simulation results are very important for the process and die design of the polymer extrusion.

Studies on the pretreatment of zeolite clinoptilolite in packed beds

The effect of volumetric flow rate, ranging from 5 to 45 Bed Volumes per hour (BV h‐1) and temperature, ranging from 25 to 59°C, during pretreatment of clinoptilolite on its effective capacity has been investigated. Pretreatment tests have been performed in an upflow ion exchange bed. Increased temperatures were found to increase the effective capacity of clinoptilolite. Effective capacity was maximal at low volumetric flow rates, indicating an influence of contact time and complete saturation of the zeolite bed at flow rates lower than 10 BV h‐1 Furthermore, a comparison between upflow and downflow operation at the same operating conditions showed that better results are obtained in upflow conditions, probably due to the better wetting of the material and the absence of liquid maldistribution.

Studies on pinched sluice concentration. Part II: Characterization of flow over a pinched sluice

A series of tests were carried out to determine characteristics of the flows over pinched sluices. Effects of volumetric flow rate, feed % solids and slope angle on flow height were measured. An empirical model was developed to define the relationship between operating variables and flow height. Within the experimental range, Reynolds numbers varied between 1200 and 5000, implying that the flow could be classified as upper transitional to turbulent depending on operating conditions. Data also show that turbulence can be suppressed by increasing feed % solids. On the basis of Froude numbers the whole range is classified as supercritical since they varied between 2.6 and 6.7. The abilities of laminar flow, Manning and smooth turbulent flow equations to predict mean flow velocities were tested. None of the equations provided a satisfactory fit to experimental data. The Manning equation was successfully modified into a model to define the relationship between operating variables and mean flow velocities.

Squeeze Air Films between Rigid and Compliant Surfaces. 2nd Report. Effects of Central Air Source.

In this paper, an experimental study is presented for the squeeze film problem between rigid and compliant surfaces with a central air source. The lower squeezing plate is a compliant one and is fixed to an electric vibrator. The upper squeezing plate is a rigid floating body supported by squeeze air film. The weight of the floating upper plate is 1.75 N to 3.75 N and the range of frequency of vibration is 0.5kHz to 1.8kHz. The effects of volumetric flow rate, exciting frequency and amplitude of the squeezing plate on the characteristics of squeeze air film are investigated. Numerical analysis is also conducted for a simplified model. It is found that the combined effects of static pressure of the central air source and squeeze effects improve the load carrying capacity and stability of the floating mass.