{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/82443"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/82443","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Conformational and Orientational Dynamics of Semi-Rigid Macromolecules in Shear Flow","abstract":"\"The third study involves the conformational and phase stability of aqueous Poly-L-Lysine solutions in shear flow. Poly-L-lysine exists as an $\\alpha$-helix at high pH and a random coil at neutral pH. When the $\\alpha$-helix is heated above 27$\\sp\\circ$C, the macromolecule undergoes a conformational transition to a $\\beta$-sheet. In this study, the stability of the secondary structure of poly-L-lysine in solutions subjected to shear flow, at temperatures below the $\\alpha$-helix to $\\beta$-sheet transition temperature, were examined using Raman spectroscopy and circular dichroism (CD). Solutions initially in the $\\alpha$-helical state showed time-dependent increases in viscosity with shearing, rising to values as much as an order of magnitude. Visual observation and turbidity measurements showed the formation of a gel like phase under flow. Laser Raman measurements demonstrated the presence of small amounts of $\\beta$-sheet structure evidenced by the amide I band at 1666 cm$\\sp{-1}$. CD measurements indicated that solutions of predominantly $\\alpha$-helical conformation at 20$\\sp\\circ$C transformed into 85% $\\alpha$-helix and 15% $\\beta$-sheet after being sheared for 20 minutes. However, on continued shearing the content of $\\beta$-sheet conformation decreased. The observed phenomena were explained in terms of a \"\"zipping up\"\" molecular model based on flow enhanced hydrophobic interactions similar to that observed in gel-forming flexible polymers. (Abstract shortened by UMI.).\"","abstract_html":"&quot;The third study involves the conformational and phase stability of aqueous Poly-L-Lysine solutions in shear flow. Poly-L-lysine exists as an <span class=\"etd-inline-math\">&alpha;</span>-helix at high pH and a random coil at neutral pH. When the <span class=\"etd-inline-math\">&alpha;</span>-helix is heated above 27$\\sp\\circ$C, the macromolecule undergoes a conformational transition to a <span class=\"etd-inline-math\">&beta;</span>-sheet. In this study, the stability of the secondary structure of poly-L-lysine in solutions subjected to shear flow, at temperatures below the <span class=\"etd-inline-math\">&alpha;</span>-helix to <span class=\"etd-inline-math\">&beta;</span>-sheet transition temperature, were examined using Raman spectroscopy and circular dichroism (CD). Solutions initially in the <span class=\"etd-inline-math\">&alpha;</span>-helical state showed time-dependent increases in viscosity with shearing, rising to values as much as an order of magnitude. Visual observation and turbidity measurements showed the formation of a gel like phase under flow. Laser Raman measurements demonstrated the presence of small amounts of <span class=\"etd-inline-math\">&beta;</span>-sheet structure evidenced by the amide I band at 1666 cm$\\sp{-1}$. CD measurements indicated that solutions of predominantly <span class=\"etd-inline-math\">&alpha;</span>-helical conformation at 20$\\sp\\circ$C transformed into 85% <span class=\"etd-inline-math\">&alpha;</span>-helix and 15% <span class=\"etd-inline-math\">&beta;</span>-sheet after being sheared for 20 minutes. However, on continued shearing the content of <span class=\"etd-inline-math\">&beta;</span>-sheet conformation decreased. The observed phenomena were explained in terms of a &quot;&quot;zipping up&quot;&quot; molecular model based on flow enhanced hydrophobic interactions similar to that observed in gel-forming flexible polymers. (Abstract shortened by UMI.).&quot;","abstract_has_math":true,"creators":["Immaneni, Aravind"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Chemical Engineering","degree_department":null,"school":null,"contributors":["McHugh, A.J."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2015,"date_issued":"2015-09-25T20:44:05Z","date_published":"2015-09-25T20:44:05Z","updated_at":"2026-07-22T22:26:18Z","subjects":["Engineering, Chemical"],"languages":["eng"],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["(MiAaPQ)AAI9812639"],"render_values":[{"text":"(MiAaPQ)AAI9812639","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/82443","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["McHugh, A.J."]},{"key":"dc:creator","label":"Author","values":["Immaneni, Aravind"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2015-09-25T20:44:05Z","10000-01-01","1997"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Chemical Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Engineering, Chemical"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/82443","(MiAaPQ)AAI9812639"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["\"The third study involves the conformational and phase stability of aqueous Poly-L-Lysine solutions in shear flow. Poly-L-lysine exists as an $\\alpha$-helix at high pH and a random coil at neutral pH. When the $\\alpha$-helix is heated above 27$\\sp\\circ$C, the macromolecule undergoes a conformational transition to a $\\beta$-sheet. In this study, the stability of the secondary structure of poly-L-lysine in solutions subjected to shear flow, at temperatures below the $\\alpha$-helix to $\\beta$-sheet transition temperature, were examined using Raman spectroscopy and circular dichroism (CD). Solutions initially in the $\\alpha$-helical state showed time-dependent increases in viscosity with shearing, rising to values as much as an order of magnitude. Visual observation and turbidity measurements showed the formation of a gel like phase under flow. Laser Raman measurements demonstrated the presence of small amounts of $\\beta$-sheet structure evidenced by the amide I band at 1666 cm$\\sp{-1}$. CD measurements indicated that solutions of predominantly $\\alpha$-helical conformation at 20$\\sp\\circ$C transformed into 85% $\\alpha$-helix and 15% $\\beta$-sheet after being sheared for 20 minutes. However, on continued shearing the content of $\\beta$-sheet conformation decreased. The observed phenomena were explained in terms of a \"\"zipping up\"\" molecular model based on flow enhanced hydrophobic interactions similar to that observed in gel-forming flexible polymers. (Abstract shortened by UMI.).\"","Made available in DSpace on 2015-09-25T20:44:05Z (GMT). No. of bitstreams: 2 license.txt: 4848 bytes, checksum: 96035ab3f5e1c23cc7138a224ce498bd (MD5) 9812639.pdf: 5496219 bytes, checksum: 524b4c668b4dd7dbb527d83824b21aea (MD5) Previous issue date: 1997","Embargo set by: Seth Robbins for item 83724 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","U of I Only","140 p.","Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1997."]},{"key":"dc:title","label":"Title","values":["Conformational and Orientational Dynamics of Semi-Rigid Macromolecules in Shear Flow"]}]}],"canonical_facts":{"dc:contributor":["McHugh, A.J."],"dc:creator":["Immaneni, Aravind"],"dc:date":["2015-09-25T20:44:05Z","10000-01-01","1997"],"dc:description":["\"The third study involves the conformational and phase stability of aqueous Poly-L-Lysine solutions in shear flow. Poly-L-lysine exists as an $\\alpha$-helix at high pH and a random coil at neutral pH. When the $\\alpha$-helix is heated above 27$\\sp\\circ$C, the macromolecule undergoes a conformational transition to a $\\beta$-sheet. In this study, the stability of the secondary structure of poly-L-lysine in solutions subjected to shear flow, at temperatures below the $\\alpha$-helix to $\\beta$-sheet transition temperature, were examined using Raman spectroscopy and circular dichroism (CD). Solutions initially in the $\\alpha$-helical state showed time-dependent increases in viscosity with shearing, rising to values as much as an order of magnitude. Visual observation and turbidity measurements showed the formation of a gel like phase under flow. Laser Raman measurements demonstrated the presence of small amounts of $\\beta$-sheet structure evidenced by the amide I band at 1666 cm$\\sp{-1}$. CD measurements indicated that solutions of predominantly $\\alpha$-helical conformation at 20$\\sp\\circ$C transformed into 85% $\\alpha$-helix and 15% $\\beta$-sheet after being sheared for 20 minutes. However, on continued shearing the content of $\\beta$-sheet conformation decreased. The observed phenomena were explained in terms of a \"\"zipping up\"\" molecular model based on flow enhanced hydrophobic interactions similar to that observed in gel-forming flexible polymers. (Abstract shortened by UMI.).\"","Made available in DSpace on 2015-09-25T20:44:05Z (GMT). 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