Bolus disperse

Calamante, E, P.J. Yim, J.R. Cebral, Estimation of bolus dispersion effects in perfusion MRI using image-based computational fluid dynamics. Neuroimage, 2003.19(2 Pt 1) p. 341-53. 

Brand P, Kohlhaufl M, Meyer T, 8elzer T, Heyder 1, Haussinger K. Aerosol-derived airway morphometry and aerosol bolus dispersion in patients with lung fibrosis and lung emphysema. Chest 1999 116 543-548. 

Brown JS, Gerrity TR, Bennett WD. Effect of ventilation distribution on aerosol bolus dispersion and recovery. J Appl Physiol 1998 85 2112-2117. 

Rosenthal FS, Blanchard ID, Anderson PJ. Aerosol bolus dispersion and convective mixing in human and dog lungs and physical models. J Appl Physiol 1992 73 862-873. 

Blanchard ID. Aerosol bolus dispersion and aerosol-derived airway morphometry Assessment of lung pathology and response to therapy. Part 1. J Aerosol Med 1996 9 183-206. 

Espinosa FF, Kamm RD (1999) Bolus dispersal through the lungs in surfactant replacranem therapy. J Appl Physiol 86(1) 391 10... 

Espinosa, F. F and R. D. Kamm, Bolus dispersal through the lungs in surfactant replacement therapy, J. Appl. Physiol., 86 391-410, 1999. 

Deconvolution softwares allow much lower injection rates—5 ml/s as reported above—compared to other softwares that use different approaches, such as the maximal slope model (Wintermark et ab 2001a). These lower injection rates are more practical and tolerable for patients. They do not impair accuracy, since the deconvolution analysis controls for bolus dispersion by comparing the arterial input time-attenuation curve with that of the tissue (Wintermark et al. 2001a). 

Aerosol bolus dispersion technique has been used for studying airway di-... 

Schulz H, Schulz A, Heyder J. Influence of intrinsic particle properties on parameters of aerosol bolus dispersion. Exp Lung Res 1996 22 393-407. 

An alternative method of calibration involves the dispersion of monodisperse polystyrene microparticles. This has recently been made an efficient process by the incorporation of these particles in pMDI suspension to allow for metering of small well-dispersed boluses sufficient for use as aerosol calibration standards [43]. 

Whipple, Chen, and Wang S showed that the distribution of an inhaled aerosol bolus depends on the orientation of the successive airway bifurcations and the volume of the bolus. On the basis of skewed velocity profiles, they made theoretical calculations of the distribution of aerosol boli in branching airways that were in fair agreement with the experimental data. Their results suggested that slow and shallow breaths should show greater differences in dispersion of irritant gases in the airways. 

Whipple, R. T., W. R. Chen, and C. S. Wang. The Dispersion of Aerosol Boluses in a System of Repeatedly Branching Tubes. Paper No. 19-D Presented at the 75th Meeting of the AIChE (American Institute of Chemical Engineers), Detroit, Mich., June 3-6, 1973. 21 pp. 

Darquenne, C., Brand, P, Heyder, J., and Paiva, M. (1997). Aerosol dispersion in human lung comparison between numerical simulations and experiments for bolus tests. J. Allied Physiol., 83, 966-974. 

Roberts, M.S. Rowland, M. A dispersion model of hepatic ehmination 1. formulation of the model and bolus considerations. J. Pharmacokinet. Biopharm. 1986, 14, 227-260. 

The principal attractions of one-dimensional EDMs are their ability to implement time dependence of the aerosol properties at the respiratory tract entrance (e.g., variations in aerosol concentration and size associated with a burst, or bolus, of inhaled particles), the ease with which simple models of axial dispersion can be incorporated, as well as their ability to include time dependence of the lung geometry associated with lung inflation during inhalation [39-41]. When any of these effects are deemed important, then one-dimensional EDMs are advantageous over the other simpler approaches we have considered thus far. 

In the analysis of residence time distributions, it is conventional to normalize time using the mean residence time of a noneliminated bolus input. This makes the normalized mean residence time (f ) of the signal in the dispersion model fi=l. 

This mode of flow analysis was proposed [128] as a means of easily and efficiently achieving extended sample handling times without excessive sample dispersion. The sample volume is inserted into an unsegmented carrier stream, and two air plugs are added at its ends in order to minimise sample broadening, and hence axial dispersion. The beneficial effects arising from the presence of air plugs at both ends of the sample bolus were already emphasised in 1972, in relation to a chemilumino-metric determination of low concentrations of Cr(III) [129]. 

As a result of the injection process, humped peaks formed by the dispersion process alone can be observed in a single-line FIA system under conditions of laminar flow provided that the reduced time t = Dm//(0.5rf) is close to 0.04, where Dm is the diffusion coefficient (cm /s), d is the diameter of the tube, and t is the time. This observation for FIA was first described by Vanderslice et al. [142], who also recently computed and depicted in an elegant way the microstructure of flow boluses under lam-... 

Concentration profiles for diffusion from a point source. When a concentrated bolus of solute is deposited within a small region of an infinitely long cylinder, as shown in Figure 3.4a, the molecules slowly disperse along the axis of the cylinder. The curves shown here are realization of Equation 3-34 for a solute with = 10-R = 0.1 cm, N = 1Vav and r = 6, 24, and 72 h. 

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