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Cross-Linked Polymers for Drug Delivery Systems
Published in Munmaya K. Mishra, Applications of Encapsulation and Controlled Release, 2019
The nasal cavity is made up of three regions: respiratory, olfactory, and vestibule 50–53. The anterior region of the nasal cavity, which is surrounded by cartilage with small hairs, is known as the nasal vestibule. The nasal turbinates are responsible for the turbulent airflow through the nasal passages, thereby resulting in a good contact between the inhaled air and the mucosal surface found in the respiratory region. The respiratory region contains four important cell types, which are involved in the active transport processes, in mucociliary clearance, and in trapping moisture, thereby keeping the mucosa moist; these are the basal, goblet, non-ciliated, and ciliated columnar cells present in the respiratory epithelium. The ciliated and non-ciliated cells enhance the surface area, and this is a region where drug absorption occurs50–53.
Imaging of the nasopharynx, face and neck
Published in Sarah McWilliams, Practical Radiological Anatomy, 2011
o There are three pairs of bony conchae also called turbinates when including the mucosa in the nasal cavity: the superior, middle and inferior. The middle turbinates may be excessively pneumatized, called the concha bullosa. This may obstruct the ostiomeatal complex.
Evaluation of nasal function after endoscopic endonasal surgery for pituitary adenoma: a computational fluid dynamics study
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2022
Miao Lou, Luyao Zhang, Simin Wang, Ruiping Ma, Minjie Gong, Zhenzhen Hu, Jingbin Zhang, Yidan Shang, Zhenbo Tong, Guoxi Zheng, Ya Zhang
Surgery affects the distribution of airflow in different parts of the nasal cavity. Based on an analysis of the distribution in a typical section (C7), we found that MTR significantly improves airflow in the middle part of the ipsilateral nasal cavity, and reduces airflow to all other parts of the nasal cavity, a redistribution we have termed the "RE-DI phenomenon". The decrease in airflow in the upper part of the nasal cavity caused a reduction in airflow contacting the olfactory mucous membrane, possibly resulting in anosmia after surgery. However, the effect of MTR on olfaction remains controversial at present. Frank-Ito et al. (2015) believed that MTR hindered the interaction between olfactory mucosal membrane and airflow, Friedman et al. (1996) found that there was no significant change in olfactory score before and after MTR, while Soler et al. (2010) believed that olfaction in patients receiving bilateral MTR increased. The current study was based on steady-state respiration and did not simulate deep inhalation of odors, which may be an explanation for the different conclusions. The reduction in airflow in the lower parts of the nasal cavity decreases shear force on the inferior turbinate wall, possibly increasing the occurrence of empty nose syndrome (ENS), as concluded by the study of Maza et al. (2019).
Voxel-based simulation of flow and temperature in the human nasal cavity
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2020
Shinya Kimura, Shuta Miura, Toshihiro Sera, Hideo Yokota, Kenji Ono, Denis J. Doorly, Robert C. Schroter, Gaku Tanaka
Figure 5 shows the DNS results for a voxel model of the same order as the Kolmogorov scale with a grid width of 0.05 mm, as well as the results of dye visualization experiments. The black line in the figure indicates the results of the experiment and the red line indicates the results of the simulation. The dye injection position in the visualization experiment and the starting point of the streakline in the analysis were selected upwind of the flow, impinging the middle turbinate where instability occurs. In the analysis results, the flow in the left nasal cavity was straight until it impinged on the middle turbinate, as in the experiment. An unstable fluctuation occurred downstream from the middle turbinate, and it was confirmed that the flow diffused from the nasal vestibule to the olfactory cleft. This simulation result sufficiently reproduced the tendency of unstable flow confirmed in the dye visualization experiment. The reproduction of high Reynold numbers turbulence, such as sniffs, is a subject for future study.
Computational modelling of nasal respiratory flow
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2020
H. Calmet, K. Inthavong, H. Owen, D. Dosimont, O. Lehmkuhl, G. Houzeaux, M. Vázquez
Results for the lower resolution simulations with no explicit turbulence model (labelled as laminar) showed the overall trends matched well with the LES results. The fluctuations had lower amplitudes with much less frequency, which is expected since the time step was larger. This was confirmed where the mean velocity contours were very similar, but some differences were observed in the instantaneous velocity field between the two models. An analysis of the temporal velocity fluctuations at relevant locations in the nasal cavity (nasal valve, nasopharynx, and turbinate) showed significant differences but was limited to the exhalation period between t = 2 s to 2.4 s. A spectral analysis confirmed that the fluctuations were features of flow turbulence.