Ten subjects underwent treadmill exercise at 5.6 km/h over one hour while wearing each of three identical appearing, cup-shaped, prototype filtering facepiece respirators that differed only in their filter resistances (3 mm, 6 mm, and 9 mm H2O pressure drop). There were no statistically significant differences between filtering facepiece respirators with respect to impact on physiological parameters (i.e., heart rate, respiratory rate, oxygen saturation, transcutaneous carbon dioxide levels, tympanic membrane temperature), pulmonary function variables (i.e., tidal volume, respiratory rate, volume of carbon dioxide production, oxygen consumption, or ventilation), and subjective ratings (i.e., exertion, thermal comfort, inspiratory effort, expiratory effort and overall breathing comfort). The nominal filter resistances of the prototype filtering facepiece respirators correspond to airflow resistances ranging from 2.1 - 6.6 mm H2O/L/s which are less than, or minimally equivalent to, previously reported values for the normal threshold for detection of inspiratory breathing resistance (6 - 7.6 mm H2O/L/sec). Therefore, filtering facepiece respirators with filter resistances at, or below, this level may not impact the wearer differently physiologically or subjectively from those with filter resistances only slightly above this threshold at low-moderate work rates over one hour.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTransient shear response and flow-induced microstructure of isotropic and nematic rigid-rod poly(p-phenylenebenzobisthiazole) solutionsAndrea W. Chow, Richard D. Hamlin, and Caroline M. YlitaloCite this: Macromolecules 1992, 25, 26, 7135–7144Publication Date (Print):December 1, 1992Publication History Published online1 May 2002Published inissue 1 December 1992https://pubs.acs.org/doi/10.1021/ma00052a010https://doi.org/10.1021/ma00052a010research-articleACS PublicationsRequest reuse permissionsArticle Views98Altmetric-Citations23LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
A rheo-optical technique to measure dynamic infrared dichroism was used with deuterium labeling to study component relaxation in a variety of multi component polymer melts. For each sample overall relaxation was observed simultaneously using birefringence measurements.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTComponent relaxation dynamics in a miscible polymer blend: poly(ethylene oxide)/poly(methyl methacrylate)Jeffrey A. Zawada, Caroline M. Ylitalo, Gerald G. Fuller, Ralph H. Colby, and Timothy E. LongCite this: Macromolecules 1992, 25, 11, 2896–2902Publication Date (Print):May 1, 1992Publication History Published online1 May 2002Published inissue 1 May 1992https://pubs.acs.org/doi/10.1021/ma00037a017https://doi.org/10.1021/ma00037a017research-articleACS PublicationsRequest reuse permissionsArticle Views755Altmetric-Citations103LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMolecular weight dependence of component dynamics in bidisperse melt rheologyCaroline M. Ylitalo, Julia A. Kornfield, Gerald G. Fuller, and Dale S. PearsonCite this: Macromolecules 1991, 24, 3, 749–758Publication Date (Print):February 1, 1991Publication History Published online1 May 2002Published inissue 1 February 1991https://pubs.acs.org/doi/10.1021/ma00003a019https://doi.org/10.1021/ma00003a019research-articleACS PublicationsRequest reuse permissionsArticle Views232Altmetric-Citations44LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
Simultaneous measurement of infrared dichroism and birefringence was used to study orientational coupling effects between a series of monodisperse polybutadiene oligomers and the surrounding matrix, which consisted of either polybutadiene polymer melt or polybutadiene network. The oligomers had molecular weights ranging from well below the critical molecular weight for entanglement Me, to several times Me. For the oligomer/network system, the magnitude of the coupling coefficient was found to remain constant at about unity over the range of network crosslink densities, oligomer molecular weights and degrees of swelling examined, thereby confirming the D n.m.r. experiments performed on the same samples. For the oligomer/polymer system, orientational coupling effects were examined as a function of oligomer molecular weight and temperature. It was found that unentangled oligomers experienced almost complete coupling, while fully entangled melts were subject to a much lower coupling. In addition, it was found that the magnitude of the coupling is independent of temperature, indicating that these orientation correlations are entropic in nature, arising from the packing entropy of chain segments. An orientational dependent lattice model, proposed originally by DiMarzio, was found suitable for predicting experimental results.
Objectives: This study was undertaken to determine the mean peak filter resistance to airflow (R filter ) encountered by subjects while wearing prototype filtering facepiece respirators (PRs) with low R filter during nasal and oral breathing at sedentary and low-moderate work rates.Material and Methods: In-line pressure transducer measurements of mean R filter across PRs with nominal R filter of 29.4 Pa, 58.8 Pa and 88.2 Pa (measured at 85 l/min constant airflow) were obtained during nasal and oral breathing at sedentary and low-moderate work rates for 10 subjects.Results: The mean R filter for the 29.4 PR was significantly lower than the other 2 PRs (p < 0.000), but there were no significant differences in mean R filter between the PRs with 58.8 and 88.2 Pa filter resistance (p > 0.05).The mean R filter was greater for oral versus nasal breathing and for exercise compared to sedentary activity (p < 0.001).Conclusions: Mean oral and nasal R filter for all 3 PRs was at, or below, the minimal threshold level for detection of inspiratory resistance (the 58.8-74.5 Pa/l×s -1 ), which may account for the previously-reported lack of significant subjective or physiological differences when wearing PRs with these low R filter .Lowering filtering facepiece respirator R filter below 88.2 Pa (measured at 85 l/min constant airflow) may not result in additional subjective or physiological benefit to the wearer.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTemperature effects on the magnitude of orientational coupling interactions in polymer meltsCaroline M. Ylitalo and Gerald G. FullerCite this: Macromolecules 1991, 24, 20, 5736–5737Publication Date (Print):September 1, 1991Publication History Published online1 May 2002Published inissue 1 September 1991https://doi.org/10.1021/ma00020a041RIGHTS & PERMISSIONSArticle Views34Altmetric-Citations5LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (260 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts
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