Particle Deposition In Respiratory Tract Research Articles

Particle deposition in respiratory tract casts for extrapolation modeling

This study compares the mechanical response and microstructure of Co–Cr–Mo removable partial denture models made through conventional lost-wax casting and the selective laser melting additive manufacturing process. Co–Cr–Mo clasps for removal partial dentures, based on a wax model (BEGO USA), were fabricated through lost-wax technique and selective laser melting, and subjected to mechanical bending experiments to determine their yield strength and maximum reversible deformation. Single-Factor Analysis of Variance (ANOVA) was used to compare data from the two populations. Microstructure and chemical composition of the clasps were determined through scanning electron microscopy and wave-dispersive spectroscopy to rationalize the differences and similarities in the mechanical testing results from the two groups.It was found that the clasps made using lost-wax technique and selective laser melting exhibit comparable mean yield strengths and maximum elastic deformations, however the underlying microstructure of the cast clasps vastly differs from the laser-melted counterparts. Furthermore, the laser melted clasps exhibit larger variability in their mechanical response. While selective laser melting is capable of producing removable partial denture clasps with similar average mechanical responses to those of lost-wax cast counterparts, additional studies should be conducted to minimize the variability in the laser melted clasps in order to minimize unexpected failures.

Respiratory tract deposition of 99mTc-labelled drug particles administered via a dry powder inhaler

Drug particle deposition in respiratory tract after inhalation from dry powder inhaler was evaluated. Disodium cromoglycate particles were labelled with a pure γ-radiator, 99mTc, using a co-precipitation technique based on spray drying. Labelled drug particles were mixed with lactose, packed in gelatin capsules and inhaled using the dry powder inhaler. Fractional deposition in the whole lung area, upper airways and stomach as well as in the inhaler was monitored using a gamma camera. Inhalations of 7 patients showed that on average 16.4% of the dry powder dose was deposited in bronchial and alveolar stages of the lungs. This fraction is almost twice as large as the previously reported lung depositions after administration from the metered dose asthma aerosols. The majority of the drug not deposited in the lungs remained in the inhaler. Thus there was clearly less of the untherapeutically used drug in the mouth, oesophagus and stomach than after administration from metered dose aerosols. The results pointed out a better bioavailability of the drug dose administered with the dry powder drug from than with the conventional metered dose aerosol drug form. The behaviour of the drug particles during the inhalation is, however, strongly dependent on the formulation of the powder mixture as well as on the construction of the powder inhaler.

The Plane Parallel Flow of a Binary Mixture of Fluids

The flow of a binary mixture of chemically inert incompressible, Newtonian fluids over an infinite plate, set into motion in its plane by impulse and by oscillation, is studied. The binary mixture consists of (i) two different viscous density nonstratified fluids, and (ii) two different viscous density stratified fluids. The exact solutions are obtained using two methods, (i) Laplace transform and (ii) Hankel transform. To further study the velocities and the wall shear stress, asymptotic expansion are found for small and large times. Some other results of physical importance such as results for noninteracting fluids, strongly interacting fluids, and extremely different fluids are also derived and compared analytically with other results. Finally, to gain an insight into the patterns of the flow, numerical study of the results has been made in detail using digital computer. A strong motivation of the present analysis has been the hope that such a theory of fluids is useful in providing some insight in rheological properties of complex fluids as polymers, liquid crystals and, in particular, blood in the vessels of small diameter. Also the theory of fluids might provide an improved understanding of such diverse subjects as diffusion of proteins, swimming of micro-organism and particle deposition in respiratory tract.