The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform

Maosheng Yao - One of the best experts on this subject based on the ideXlab platform.

  • Airflow Resistance and bio filtering performance of carbon nanotube filters and current facepiece respirators
    Journal of Aerosol Science, 2015
    Co-Authors: Zhuanglei Zou, Maosheng Yao
    Abstract:

    Abstract This study aimed to study Airflow Resistance of carbon nanotube (CNT)-based filtration material and compare its bioaerosol filtering performances with commercially available facepiece respirators. Firstly, we developed a manikin-based system to evaluate the filtering performances of six respiratory masks for biological aerosol particles using an Ultraviolet Aerodynamic Particle Sizer (UV-APS). Secondly, CNT filters with a base filter with a pore size of 10 μm were prepared using single-walled carbon nanotube (SWNT) loadings of 0.05, 0.1 and 0.2 mg/cm 2 . In addition, mask filter membranes were also made by manually cutting the materials of the tested respiratory masks, and their filtration efficiencies and pressure drops were measured and compared with those of CNT-based filters. Results indicated that most of the studied respirator masks achieved a practical protection efficiency of >90%, while N95 types obtained more than 99% absolute protection efficiency under fully sealed conditions. Increasing CNT loading was shown to increase the quality factor (QF) for the CNT filter given all the sizes considered. For the loading of 0.2 mg/cm 2 , CNT filters achieved 87% filtration efficiency against indoor viable bioaerosols and 70% for outdoor aerosol particles; and its QF was significantly higher than those of base filter, activated carbon and surgical mask filters. Different from other mask filters, CNT filters were observed to have higher biological aerosol particle filtration efficiencies than the total aerosol particles. Future work in improving air permeability of CNT filter and CNT distribution on filter support would lead to next generation respiratory mask.

Charles G Irvin - One of the best experts on this subject based on the ideXlab platform.

  • it s not all smooth muscle non smooth muscle elements in control of Resistance to Airflow
    Annual Review of Physiology, 2010
    Co-Authors: Ynuk Bosse, Erik P Riesenfeld, Peter D Pare, Charles G Irvin
    Abstract:

    To achieve gas exchange, inspired air must pass through an intricate and dynamic tracheobronchial tree. The tree offers Resistance to Airflow, and increased Resistance is the most important functional change in lung disease. Numerous mechanisms contribute to increased Resistance by causing airway narrowing, closure, occlusion, and/or obliteration. Although airway smooth muscle (ASM) contraction and shortening are an important cause of increased Resistance, non-ASM elements can also contribute. Nonmuscle elements can modify the amount of airway narrowing for any given level of ASM shortening and the amount of shortening for a given level of ASM activation. In this review, we outline the physiological basis for Airflow Resistance and describe how changes in the lung parenchyma, the airways, and their luminal contents can contribute to increased Airflow Resistance. A detailed understanding of the mechanisms and consequences of increased airway Resistance is vital to our attempts to alleviate the enormous burden of suffering caused by obstructive lung diseases.

H Lorino - One of the best experts on this subject based on the ideXlab platform.

  • effects of nasal prongs on nasal Airflow Resistance
    Chest, 2000
    Co-Authors: A M Lorino, Estelle Dahan, A Harf, H Lorino, M P Dortho, Andre Coste, Frederic Lofaso
    Abstract:

    Study objectives The aim of this study was to investigate whether nasal prongs, which have been proposed to assess nasal flow during sleep, affect nasal Airflow Resistance (NR). Design NR was estimated by posterior rhinomanometry at a 0.5 L/s flow, under eight conditions: in the basal state, and with seven different nasal prongs. Participants The study was performed in 17 healthy supine subjects, 8 of whom had basal NR values within the normal range (≤ 2 cm H 2 O·L −1 ·s, group 1), and 9 had increased basal NR values (> 2.5 cm H 2 O·L −1 ·s, group 2), because of nare narrowness and/or deviated nasal septum. Measurements and results NR increased significantly while breathing with nasal prongs (p 2 O·L −1 ·s. Significant differences were found between the ΔNR induced by the different nasal prongs (p Conclusions This study demonstrates that nasal prongs can markedly increase NR in subjects presenting with nare narrowness and/or deviated nasal septum. Further investigations that would include nocturnal polysomnography are still required to evaluate the possible influence of nasal prongs on the diagnosis of obstructive sleep apnea syndrome and its severity.

  • combined effects of a mechanical nasal dilator and a topical decongestant on nasal Airflow Resistance
    Chest, 1999
    Co-Authors: A M Lorino, Frederic Lofaso, Estelle Dahan, A Harf, Andre Coste, H Lorino
    Abstract:

    The goal of this study was to compare the isolated and combined effects of two treatments being used to reduce nasal Airflow Resistance (NR): an internal nasal mechanical dilator (Nozovent; Prevancure; Ste Pouret, Paris, France) and a topical decongestant, fenoxazoline hydrochloride (Aturgyl; Synthelabo; Le Plessis-Robinson, France). The study was performed in 17 healthy subjects. NR was estimated by active posterior rhinometry at a 0.5 L/s flow under four conditions: in the basal state, with the internal nasal mechanical dilator, after treatment with fenoxazoline hydrochloride , and with both fenoxazoline hydrochloride and the mechanical dilator. The mean NR (± SD) decreased from 1.65 ± 0.54 cm H 2 O/L/s in the basal state to 1.02 ± 0.27 cm H 2 O/L/s with the mechanical dilator (p 2 O/L/s with fenoxazoline hydrochloride (p 2 O/L/s with both the mechanical dilator and fenoxazoline hydrochloride (p n ) or fenoxazoline hydrochloride (ΔNR a ) were not significantly different. The decrease in NR observed with both (ΔNR n + a ) was not significantly different from the sum Δ NR n + ΔNR a: 1.16 ± 0.53 cm H 2 O/L/s vs 1.25 ± 0.63 cm H 2 O/L/s, respectively (p > 0.05). ΔNR n + a strongly correlated with ΔNR n + ΔNR a :Δ NR n + a = 0.80 (ΔNR n + ΔNR a ) + 0.15 (r = 0.96; p n + a vs Δ NR n + ΔNR a was significantly lower than unity (p

  • nasal Airflow Resistance measurement forced oscillation technique versus posterior rhinomanometry
    European Respiratory Journal, 1998
    Co-Authors: A M Lorino, Frederic Lofaso, F Abinader, Irene Drogou, Estelle Dahan, Francoise Zerah, A Harf, H Lorino
    Abstract:

    This study was designed to determine whether nasal Airflow Resistance (Rn) which is nonlinear during tidal breathing, can be assessed by the forced oscillation (FO) technique. Rn values obtained by the FO technique and extrapolated to 0 Hz (Rn,FO) were compared to those assessed by posterior rhinomanometry at maximal tidal inspiratory flow (Rn,m), at a 0.5 L x s(-1) flow (Rn,F), and at a 1 hPa transnasal pressure (Rn,P). All Rn estimates were derived from the same inspiratory and expiratory nasal flow and transnasal pressure signals obtained during tidal nasal breathing whilst a forced flow was applied at the nose via a rigid nasal mask in 23 healthy volunteers, of whom 14 had additional measurements after vasoconstrictor treatment. In the basal state, no significant difference, and significant correlations (p

N B Pride - One of the best experts on this subject based on the ideXlab platform.

  • topical salmeterol reduces protein content of nasal lavage fluid in response to allergen and histamine challenge double blind cross over placebo controlled studies in adults
    American Journal of Rhinology, 1996
    Co-Authors: Martin A Birchall, N B Pride, Finbarr Oconnell, Jane Henderson, Alison Moorat, Loretta Jacques, R W Fuller
    Abstract:

    We have studied the effects of topical intranasal β-2-adrenoceptor agonists on nasal Airflow Resistance (Rnaw) and secretions. Pretreatment with salmeterol (SM) and salbutamol (SB) was given in two...

  • comparison of four methods of assessing Airflow Resistance before and after induced airway narrowing in normal subjects
    Journal of Applied Physiology, 1995
    Co-Authors: S B Phagoo, R A Watson, M Silverman, N B Pride
    Abstract:

    Four methods for assessing Airflow Resistance were compared in seven normal adults at baseline and after inducing airway narrowing with inhaled methacholine. Airway Resistance (Raw) was measured during panting at 1–2 Hz within a body plethysmograph; total lung Resistance was measured by using an esophageal balloon during quiet breathing (RLq) and with doubling of frequency while maintaining the original tidal volume; total respiratory Resistance (Rrs) was measured at 6 Hz during forced oscillation applied at the airway opening, and interruption Resistance (Rint) was measured at midtidal expiratory flow. Three methods of obtaining Rint after Airflow interruption were compared [smooth curve fit of mouth pressure (Pm) back extrapolated to valve closure; two-point linear fit of Pm back extrapolated to 15 ms after closure; and Pm at 100 ms after valve closure]. We found similar basal median values (cmH2O.l-1.s) of Raw (1.3), RLq (1.4), RL of double resting frequency (1.9), Rrs (1.7), and smooth curve fit of Pm back extrapolated to valve closure (1.5); basal values of two-point linear fit of Pm back extrapolated to 15 ms after closure (2.4) and Pm at 100 ms after valve closure (4.4) were considerably larger. After induced airway narrowing, all methods of measuring Resistance showed significant increases; these were largest with RLq (median %change of 265) and smallest with the three Rint methods (median %change of 62–72). Rint and Rrs methods had poorer sensitivity for detecting bronchoconstriction than lung Resistance of Raw. Of the Rint methods, end interruption pressure was the most sensitive.

C Ocallaghan - One of the best experts on this subject based on the ideXlab platform.

  • research articlesinvestigating improving powder deagglomeration via dry powder inhalers at a low inspiratory flow rate by employing add on spacers
    Journal of Pharmaceutical Sciences, 2008
    Co-Authors: Touraj Ehtezazi, D R Allanson, Ian Jenkinson, Ian Shrubb, C Ocallaghan
    Abstract:

    The aim of this study was to investigate whether small add‐on spacers alone or equipped with a passive deagglomerating component would improve aerosol performances of passive low Airflow Resistance dry powder inhalers (DPIs) at a low inhalation flow rate. Depositions of beclometasone dipropionate (BDP) and salbutamol sulphate (SS) via the Asmabec Clickhaler and Asmasal Clickhaler at 30 L/min Airflow rate in an oropharyngeal model and attached filter were determined. Three add‐on spacers, one with 5.0 cm length, and the other with the same features but incorporating a fine mesh, and the third one with the length of 8.5 cm (long add‐on spacer) were used. Incorporating mesh did not improve the filter dose for SS, and significantly reduced this dose for BDP. The long add‐on spacer was the most efficient spacer as it had minimal effects on the filter doses, also significantly reduced drug depositions in the model. In conclusion, an optimum length of an add‐on spacer is required to minimise oropharyngeal drug deposition via a low Airflow Resistance DPI at a low inspiratory flow rate without considerable reduction of the respirable dose. Incorporating sieves within add‐on spacers may diminish aerosol performances of the DPIs at low Airflow rates. © 2008 Wiley‐Liss, Inc. and the American Pharmacists Association J Pharm Sci 97:5212–5221, 2008

  • investigating improving powder deagglomeration via dry powder inhalers at a low inspiratory flow rate by employing add on spacers
    Journal of Pharmaceutical Sciences, 2008
    Co-Authors: Touraj Ehtezazi, D R Allanson, Ian Jenkinson, Ian Shrubb, C Ocallaghan
    Abstract:

    Abstract The aim of this study was to investigate whether small add‐on spacers alone or equipped with a passive deagglomerating component would improve aerosol performances of passive low Airflow Resistance dry powder inhalers (DPIs) at a low inhalation flow rate. Depositions of beclometasone dipropionate (BDP) and salbutamol sulphate (SS) via the Asmabec Clickhaler and Asmasal Clickhaler at 30 L/min Airflow rate in an oropharyngeal model and attached filter were determined. Three add‐on spacers, one with 5.0 cm length, and the other with the same features but incorporating a fine mesh, and the third one with the length of 8.5 cm (long add‐on spacer) were used. Incorporating mesh did not improve the filter dose for SS, and significantly reduced this dose for BDP. The long add‐on spacer was the most efficient spacer as it had minimal effects on the filter doses, also significantly reduced drug depositions in the model. In conclusion, an optimum length of an add‐on spacer is required to minimise oropharyngeal drug deposition via a low Airflow Resistance DPI at a low inspiratory flow rate without considerable reduction of the respirable dose. Incorporating sieves within add‐on spacers may diminish aerosol performances of the DPIs at low Airflow rates. © 2008 Wiley‐Liss, Inc. and the American Pharmacists Association J Pharm Sci 97:5212–5221, 2008