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1. Operational Ontology for Oncology (O3) – A Professional Society Based, Multi-Stakeholder, Consensus Driven Informatics Standard Supporting Clinical and Research use of “Real -World” Data from Patients Treated for Cancer Operational Ontology for Radiation Oncology

Author

Mayo, CS, Feng, MU, Brock, KK, Kudner, R, Balter, P, Buchsbaum, JC, Caissie, A, Covington, E, Daugherty, EC, Dekker, AL, Fuller, CD, Hallstrom, AL, Hong, DS, Hong, JC, Kamran, SC, Katsoulakis, E, Kildea, J, Krauze, AV, Kruse, JJ, McNutt, T, Mierzwa, M, Moreno, A, Palta, JR, Popple, R, Purdie, TG, Richardson, S, Sharp, GC, Shiraishi, S, Tarbox, L, Venkatesan, AM, Witztum, A, Woods, KE, Yao, J, Farahani, K, Aneja, S, Gabriel, PE, Hadjiiski, L, Ruan, D, Siewerdsen, JH, Bratt, S, Casagni, M, Chen, S, Christodouleas, J, DiDonato, A, Hayman, J, Kapoor, R, Kravitz, S, Sebastian, S, Von Siebenthal, M, and Xiao, Y

Subjects
Medical and Biological Physics, Physical Sciences, Biomedical and Clinical Sciences, Oncology and Carcinogenesis, Cancer, Networking and Information Technology R&D (NITRD), Patient Safety, Good Health and Well Being, Other Physical Sciences, Clinical Sciences, Oncology & Carcinogenesis, Oncology and carcinogenesis, Theoretical and computational chemistry, Medical and biological physics
Abstract

PurposeThe ongoing lack of data standardization severely undermines the potential for automated learning from the vast amount of information routinely archived in electronic health records (EHRs), Radiation Oncology Information Systems (ROIS), treatment planning systems (TPSs), and other cancer care and outcomes databases. The effort sought to create a standardized ontology for clinical data, social determinants of health (SDOH), and other radiation oncology concepts and interrelationships.Methods and materialsThe American Association of Physicists in Medicine's (AAPM's) Big Data Science Committee (BDSC) was initiated July of 2019 to explore common ground from the stakeholders' collective experience of issues that typically compromise the formation of large inter- and intra- institutional databases from EHRs. The BDSC adopted an iterative, cyclical approach to engaging stakeholders beyond its membership to optimize the integration of diverse perspectives from the community.ResultsWe developed the Operational Ontology for Oncology (O3) which identified 42 key elements, 359 attributes, 144 value sets, and 155 relationships ranked in relative importance of clinical significance, likelihood of availability in EHRs, or the ability to modify routine clinical processes to permit aggregation. Recommendations are provided for best use and development of the O3 to four constituencies: device manufacturers, centers of clinical care, researchers, and professional societies.ConclusionsO3 is designed to extend and interoperate with existing global infrastructure and data science standards. The implementation of these recommendations will lower the barriers for aggregation of information that could be used creating large, representative, findable, accessible, interoperable and reusable (FAIR) datasets supporting the scientific objectives of grant programs. The construction of comprehensive "real world" datasets and application of advanced analytic techniques, including artificial intelligence (AI), holds the potential to revolutionize patient management and improve outcomes by leveraging increased access to information derived from larger, more representative datasets.

Published
2023

2. HRS-Expertenkonsensus (2017) Sondenmanagement und -extraktion von kardialen elektronischen Implantaten sowie EHRA-Expertenkonsensus (2018) zur wissenschaftlichen Aufarbeitung von Sondenextraktionen: Kommentar der AG Herzrhythmusstörungen der Deutschen Gesellschaft für Thorax‑, Herz- und Gefäßchirurgie

Author

Starck, C. T., Burger, H., Osswald, B., Hakmi, S., Knaut, M., Bimmel, D., Bärsch, V., Eitz, T., Mierzwa, M., Ghaffari, N., and Siebel, A.

Published
2021
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3. Cable bacteria skeletons as catalytically active electrodes

Author

Digel, L., Mierzwa, M., Bonné, R., Zieger, S., Pavel, I., Ferapontova, E., Koren, K., Boesen, T., Harnisch, Falk, Marshall, I., Nielsen, L.P., Kuhn, A., Digel, L., Mierzwa, M., Bonné, R., Zieger, S., Pavel, I., Ferapontova, E., Koren, K., Boesen, T., Harnisch, Falk, Marshall, I., Nielsen, L.P., and Kuhn, A.

Abstract

Cable bacteria are multicellular, filamentous bacteria that use internal conductive fibers to transport electrons over centimeter distances from donors within anoxic sediment layers to oxygen at the surface. We extracted the fibers and used them as free-standing bio-based electrodes to investigate their electrocatalytic behavior. The fibers catalyzed the reversible interconversion of oxygen and water, and an electric current was running through the fibers even when the potential difference was generated solely by a gradient of oxygen concentration. Oxygen reduction as well as oxygen evolution were confirmed by optical measurements. Within living cable bacteria, oxygen reduction by direct electrocatalysis on the fibers and not by membrane-bound proteins readily explains exceptionally high cell-specific oxygen consumption rates observed in the oxic zone, while electrocatalytic water oxidation may provide oxygen to cells in the anoxic zone.

Published
2023

4. Flight Servicing of Robotic Refueling Mission 3

Author

Krenn, A, Stewart, M, Mitchell, D, Dixon, K, Mierzwa, M, and Breon, S

Subjects
Spacecraft Propulsion And Power
Abstract

The Robotic Refueling Mission 3 (RRM3) payload launched aboard a SpaceX rocket en route to the International Space Station on December 5th, 2018. The Goddard Space Flight Center designed payload carried approximately 50 liters of liquid methane onboard, with a mission to demonstrate long term storage and transfer of the cryogenic fluid in microgravity. Kennedy Space Center (KSC) was tasked to design, fabricate, test, and operate a system equipped to fill an RRM3 dewar with liquid methane prior to launch. Though KSC has a rich history of fueling rockets and payloads, no such operations had previously been accomplished using liquid methane. As such, all of the hardware and processes had to be developed from scratch. The completed ground system design, along with the verification and validation testing will be outlined in this paper. Several challenges that were met and overcome during procurement of the high purity methane are described. In addition, budget restrictions prohibited fueling operations from occurring in traditional processing facilities. The unique and creative solutions which were required to maintain payload cleanliness during cryogenic servicing are also detailed.

Published
2019

5. Flight Servicing of Robotic Refueling Mission 3

Author

Krenn, A. G, Stewart, M. A, Mitchell, D. M, Mierzwa, M. C, Breon, S. R, and Dixon, K. L

Subjects
Spacecraft Propulsion And Power
Abstract

The Robotic Refueling Mission 3 (RRM3) payload launched aboard a SpaceX rocket en route to the International Space Station on December 5th, 2018. The Goddard Space Flight Center designed payload carried approximately 50 liters of liquid methane onboard, with a mission to demonstrate long term storage and transfer of the cryogenic fluid in microgravity. Kennedy Space Center (KSC) was tasked to design, fabricate, test, and operate a system equipped to fill an RRM3 dewar with liquid methane prior to launch. Though KSC has a rich history of fueling rockets and payloads, no such operations had previously been accomplished using liquid methane. As such, all of the hardware and processes had to be developed from scratch. The completed ground system design, along with the verification and validation testing will be outlined in this paper. Several challenges that were met and overcome during procurement of the high purity methane are described. In addition, budget restrictions prohibited fueling operations from occurring in traditional processing facilities. The unique and creative solutions which were required to maintain payload cleanliness during cryogenic servicing are also detailed.

Published
2019

8. Practice Recommendations for Risk-Adapted Head and Neck Cancer Radiation Therapy During the COVID-19 Pandemic: An ASTRO-ESTRO Consensus Statement

Author

Thomson, D.J., Palma, D., Guckenberger, M., Balermpas, P., Beitler, J.J., Blanchard, P., Brizel, D., Budach, W., Caudell, J., Corry, J., Corvo, R., Evans, M., Garden, A.S., Giralt, J., Gregoire, V., Harari, P.M., Harrington, K., Hitchcock, Y.J., Johansen, J., Kaanders, J.H., Koyfman, S., Langendijk, J.A., Le, Q.T., Lee, N., Margalit, D., Mierzwa, M., Porceddu, S., Soong, Y.L., Sun, Y, Thariat, J., Waldron, J., Yom, S.S., Thomson, D.J., Palma, D., Guckenberger, M., Balermpas, P., Beitler, J.J., Blanchard, P., Brizel, D., Budach, W., Caudell, J., Corry, J., Corvo, R., Evans, M., Garden, A.S., Giralt, J., Gregoire, V., Harari, P.M., Harrington, K., Hitchcock, Y.J., Johansen, J., Kaanders, J.H., Koyfman, S., Langendijk, J.A., Le, Q.T., Lee, N., Margalit, D., Mierzwa, M., Porceddu, S., Soong, Y.L., Sun, Y, Thariat, J., Waldron, J., and Yom, S.S.

Abstract

Contains fulltext : 220461.pdf (Publisher’s version ) (Open Access), PURPOSE: Because of the unprecedented disruption of health care services caused by the COVID-19 pandemic, the American Society of Radiation Oncology (ASTRO) and the European Society for Radiotherapy and Oncology (ESTRO) identified an urgent need to issue practice recommendations for radiation oncologists treating head and neck cancer (HNC) in a time of limited resources and heightened risk for patients and staff. METHODS AND MATERIALS: A panel of international experts from ASTRO, ESTRO, and select Asia-Pacific countries completed a modified rapid Delphi process. Topics and questions were presented to the group, and subsequent questions were developed from iterative feedback. Each survey was open online for 24 hours, and successive rounds started within 24 hours of the previous round. The chosen cutoffs for strong agreement (>/=80%) and agreement (>/=66%) were extrapolated from the RAND methodology. Two pandemic scenarios, early (risk mitigation) and late (severely reduced radiation therapy resources), were evaluated. The panel developed treatment recommendations for 5 HNC cases. RESULTS: In total, 29 of 31 of those invited (94%) accepted, and after a replacement 30 of 30 completed all 3 surveys (100% response rate). There was agreement or strong agreement across a number of practice areas, including treatment prioritization, whether to delay initiation or interrupt radiation therapy for intercurrent SARS-CoV-2 infection, approaches to treatment (radiation dose-fractionation schedules and use of chemotherapy in each pandemic scenario), management of surgical cases in event of operating room closures, and recommended adjustments to outpatient clinic appointments and supportive care. CONCLUSIONS: This urgent practice recommendation was issued in the knowledge of the very difficult circumstances in which our patients find themselves at present, navigating strained health care systems functioning with limited resources and at heightened risk to their health during the CO

Published
2020

9. Practice recommendations for risk-adapted head and neck cancer radiotherapy during the COVID-19 pandemic: An ASTRO-ESTRO consensus statement

Author

Thomson, D.J., Palma, D., Guckenberger, M., Balermpas, P., Beitler, J.J., Blanchard, P., Brizel, D., Budach, W., Caudell, J., Corry, J., Corvo, R., Evans, M., Garden, A.S., Giralt, J., Gregoire, V., Harari, P.M., Harrington, K., Hitchcock, Y.J., Johansen, J., Kaanders, J.H., Koyfman, S., Langendijk, J.A., Le, Q.T., Lee, N., Margalit, D., Mierzwa, M., Porceddu, S., Soong, Y.L., Sun, Y, Thariat, J., Waldron, J., Yom, S.S., Thomson, D.J., Palma, D., Guckenberger, M., Balermpas, P., Beitler, J.J., Blanchard, P., Brizel, D., Budach, W., Caudell, J., Corry, J., Corvo, R., Evans, M., Garden, A.S., Giralt, J., Gregoire, V., Harari, P.M., Harrington, K., Hitchcock, Y.J., Johansen, J., Kaanders, J.H., Koyfman, S., Langendijk, J.A., Le, Q.T., Lee, N., Margalit, D., Mierzwa, M., Porceddu, S., Soong, Y.L., Sun, Y, Thariat, J., Waldron, J., and Yom, S.S.

Abstract

Contains fulltext : 229919.pdf (Publisher’s version ) (Open Access), PURPOSE: Because of the unprecedented disruption of health care services caused by the COVID-19 pandemic, the American Society of Radiation Oncology (ASTRO) and the European Society for Radiotherapy and Oncology (ESTRO) identified an urgent need to issue practice recommendations for radiation oncologists treating head and neck cancer (HNC) in a time of limited resources and heightened risk for patients and staff. METHODS AND MATERIALS: A panel of international experts from ASTRO, ESTRO, and select Asia-Pacific countries completed a modified rapid Delphi process. Topics and questions were presented to the group, and subsequent questions were developed from iterative feedback. Each survey was open online for 24 hours, and successive rounds started within 24 hours of the previous round. The chosen cutoffs for strong agreement (≥80%) and agreement (≥66%) were extrapolated from the RAND methodology. Two pandemic scenarios, early (risk mitigation) and late (severely reduced radiation therapy resources), were evaluated. The panel developed treatment recommendations for 5 HNC cases. RESULTS: In total, 29 of 31 of those invited (94%) accepted, and after a replacement 30 of 30 completed all 3 surveys (100% response rate). There was agreement or strong agreement across a number of practice areas, including treatment prioritization, whether to delay initiation or interrupt radiation therapy for intercurrent SARS-CoV-2 infection, approaches to treatment (radiation dose-fractionation schedules and use of chemotherapy in each pandemic scenario), management of surgical cases in event of operating room closures, and recommended adjustments to outpatient clinic appointments and supportive care. CONCLUSIONS: This urgent practice recommendation was issued in the knowledge of the very difficult circumstances in which our patients find themselves at present, navigating strained health care systems functioning with limited resources and at heightened risk to their health during the COVID

Published
2020

10. Practice recommendations for risk-adapted head and neck cancer radiotherapy during the COVID-19 pandemic: An ASTRO-ESTRO consensus statement.

Author

Thomson, DJ, Palma, D, Guckenberger, M, Balermpas, P, Beitler, JJ, Blanchard, P, Brizel, D, Budach, W, Caudell, J, Corry, J, Corvo, R, Evans, M, Garden, AS, Giralt, J, Gregoire, V, Harari, PM, Harrington, K, Hitchcock, YJ, Johansen, J, Kaanders, J, Koyfman, S, Langendijk, JA, Le, Q-T, Lee, N, Margalit, D, Mierzwa, M, Porceddu, S, Soong, YL, Sun, Y, Thariat, J, Waldron, J, Yom, SS, Thomson, DJ, Palma, D, Guckenberger, M, Balermpas, P, Beitler, JJ, Blanchard, P, Brizel, D, Budach, W, Caudell, J, Corry, J, Corvo, R, Evans, M, Garden, AS, Giralt, J, Gregoire, V, Harari, PM, Harrington, K, Hitchcock, YJ, Johansen, J, Kaanders, J, Koyfman, S, Langendijk, JA, Le, Q-T, Lee, N, Margalit, D, Mierzwa, M, Porceddu, S, Soong, YL, Sun, Y, Thariat, J, Waldron, J, and Yom, SS

Abstract

PURPOSE: Because of the unprecedented disruption of health care services caused by the COVID-19 pandemic, the American Society of Radiation Oncology (ASTRO) and the European Society for Radiotherapy and Oncology (ESTRO) identified an urgent need to issue practice recommendations for radiation oncologists treating head and neck cancer (HNC) in a time of limited resources and heightened risk for patients and staff. METHODS AND MATERIALS: A panel of international experts from ASTRO, ESTRO, and select Asia-Pacific countries completed a modified rapid Delphi process. Topics and questions were presented to the group, and subsequent questions were developed from iterative feedback. Each survey was open online for 24 hours, and successive rounds started within 24 hours of the previous round. The chosen cutoffs for strong agreement (≥80%) and agreement (≥66%) were extrapolated from the RAND methodology. Two pandemic scenarios, early (risk mitigation) and late (severely reduced radiation therapy resources), were evaluated. The panel developed treatment recommendations for 5 HNC cases. RESULTS: In total, 29 of 31 of those invited (94%) accepted, and after a replacement 30 of 30 completed all 3 surveys (100% response rate). There was agreement or strong agreement across a number of practice areas, including treatment prioritization, whether to delay initiation or interrupt radiation therapy for intercurrent SARS-CoV-2 infection, approaches to treatment (radiation dose-fractionation schedules and use of chemotherapy in each pandemic scenario), management of surgical cases in event of operating room closures, and recommended adjustments to outpatient clinic appointments and supportive care. CONCLUSIONS: This urgent practice recommendation was issued in the knowledge of the very difficult circumstances in which our patients find themselves at present, navigating strained health care systems functioning with limited resources and at heightened risk to their health during the COVID

Published
2020

11. Practice Recommendations for Risk-Adapted Head and Neck Cancer Radiation Therapy During the COVID-19 Pandemic: An ASTRO-ESTRO Consensus Statement.

Author

Thomson, DJ, Palma, D, Guckenberger, M, Balermpas, P, Beitler, JJ, Blanchard, P, Brizel, D, Budach, W, Caudell, J, Corry, J, Corvo, R, Evans, M, Garden, AS, Giralt, J, Gregoire, V, Harari, PM, Harrington, K, Hitchcock, YJ, Johansen, J, Kaanders, J, Koyfman, S, Langendijk, JA, Le, Q-T, Lee, N, Margalit, D, Mierzwa, M, Porceddu, S, Soong, YL, Sun, Y, Thariat, J, Waldron, J, Yom, SS, Thomson, DJ, Palma, D, Guckenberger, M, Balermpas, P, Beitler, JJ, Blanchard, P, Brizel, D, Budach, W, Caudell, J, Corry, J, Corvo, R, Evans, M, Garden, AS, Giralt, J, Gregoire, V, Harari, PM, Harrington, K, Hitchcock, YJ, Johansen, J, Kaanders, J, Koyfman, S, Langendijk, JA, Le, Q-T, Lee, N, Margalit, D, Mierzwa, M, Porceddu, S, Soong, YL, Sun, Y, Thariat, J, Waldron, J, and Yom, SS

Abstract

PURPOSE: Because of the unprecedented disruption of health care services caused by the COVID-19 pandemic, the American Society of Radiation Oncology (ASTRO) and the European Society for Radiotherapy and Oncology (ESTRO) identified an urgent need to issue practice recommendations for radiation oncologists treating head and neck cancer (HNC) in a time of limited resources and heightened risk for patients and staff. METHODS AND MATERIALS: A panel of international experts from ASTRO, ESTRO, and select Asia-Pacific countries completed a modified rapid Delphi process. Topics and questions were presented to the group, and subsequent questions were developed from iterative feedback. Each survey was open online for 24 hours, and successive rounds started within 24 hours of the previous round. The chosen cutoffs for strong agreement (≥80%) and agreement (≥66%) were extrapolated from the RAND methodology. Two pandemic scenarios, early (risk mitigation) and late (severely reduced radiation therapy resources), were evaluated. The panel developed treatment recommendations for 5 HNC cases. RESULTS: In total, 29 of 31 of those invited (94%) accepted, and after a replacement 30 of 30 completed all 3 surveys (100% response rate). There was agreement or strong agreement across a number of practice areas, including treatment prioritization, whether to delay initiation or interrupt radiation therapy for intercurrent SARS-CoV-2 infection, approaches to treatment (radiation dose-fractionation schedules and use of chemotherapy in each pandemic scenario), management of surgical cases in event of operating room closures, and recommended adjustments to outpatient clinic appointments and supportive care. CONCLUSIONS: This urgent practice recommendation was issued in the knowledge of the very difficult circumstances in which our patients find themselves at present, navigating strained health care systems functioning with limited resources and at heightened risk to their health during the COVID

Published
2020

24. Adaptive Chemoradiation Therapy for Head and Neck Cancer Based on Multiparametric MRI: Interim Results of a Prospective Randomized Trial

Author

Hawkins, P.G., primary, Lee, J.Y., additional, Li, P., additional, Lee, C., additional, Mierzwa, M., additional, Aryal, M.P., additional, Arnould, G.S., additional, Worden, F., additional, Swiecicki, P.L., additional, Spector, M.E., additional, Schipper, M., additional, Cao, Y., additional, and Eisbruch, A., additional

Published
2018
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25. Comparison of the 7 th and 8 th Editions of the AJCC/UICC Staging for Human Papillomavirus–Related Oropharynx Carcinoma

Author

Casper, K., primary, Hawkins, P.G., additional, Mierzwa, M., additional, Bellile, E., additional, Malloy, K., additional, Chinn, S.B., additional, Spector, M.E., additional, Shuman, A., additional, Stucken, C.L., additional, Mclean, S., additional, Worden, F., additional, Swiecicki, P.L., additional, Taylor, J., additional, Bradford, C.R., additional, Prince, M.E., additional, Wolf, G.T., additional, and Eisbruch, A., additional

Published
2018
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27. Correlation between primary and secondary Johari–Goldstein relaxations in supercooled liquids: Invariance to changes in thermodynamic conditions.

Author

Mierzwa, M., Pawlus, S., Paluch, M., Kaminska, E., and Ngai, K. L.

Subjects
*SUPERCOOLED liquids, *SUPERCOOLING, *THERMODYNAMICS, *EPOXY resins, *DIELECTRIC relaxation, *GLASS transition temperature
Abstract

The primary α and the secondary Johari–Goldstein (JG) β relaxations of supercooled glass-forming neat epoxy resin and 2-picoline in mixture with tristyrene are monitored by broadband dielectric relaxation spectroscopy at ambient pressure and elevated pressures. For different combinations of pressure and temperature that maintain the α-relaxation time constant, the frequency dispersion of the α relaxation is unchanged, as previously found in other glass-formers, but remarkably the JG β-relaxation time remains constant. This is more clear evidence of a strong connection between the α- and JG β-relaxation times, a fact that should be taken into account in the construction of a viable theory of glass transition. [ABSTRACT FROM AUTHOR]

Published
2008
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28. Changes of relaxation dynamics of a hydrogen-bonded glass former after removal of the hydrogen bonds.

Author

Grzybowska, K., Pawlus, S., Mierzwa, M., Paluch, M., and Ngai, K. L.

Subjects
DIELECTRIC relaxation, DIELECTRICS spectra, GLASS, HYDROGEN bonding, RELAXATION (Gas dynamics), PRESSURE, TEMPERATURE effect
Abstract

Dielectric relaxation spectra of two closely related glass formers, dipropylene glycol [H–(C3H6O)2–OH] and dipropylene glycol dimethyl ether [CH3–O–(C3H6O)2–CH3], were measured at ambient and elevated pressures in the supercooled and the glassy states are presented. Hydrogen bonds formed in dipropylene glycol are removed when its ends are replaced by two methyl groups to become dipropylene glycol dimethyl ether. In the process, the primary relaxation, the excess wing, and the resolved secondary relaxation of dipropylene glycol are all modified when the structure is transformed to become dipropylene glycol dimethyl ether. The modifications include the pressure and temperature dependences of these relaxation processes and their interrelations. Thus, by comparing the dielectric spectra of these two closely related glass formers at ambient and elevated pressures, the differences in the relaxation dynamics and properties in the presence and absence of hydrogen bonding are identified. [ABSTRACT FROM AUTHOR]

Published
2006
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29. Constrained dynamics in supramolecular structures of poly(p-phenylenes) with ethylene oxide side chains: A combined dielectric and nuclear magnetic resonance investigation.

Author

Mierzwa, M., Floudas, G., Neidhöfer, M., Graf, R., Spiess, H. W., Meyer, W. H., and Wegner, G.

Subjects
*CONSTRAINTS (Physics), *SUPRAMOLECULAR chemistry, *ETHYLENE oxide, *POLYPHENYLENE oxide
Abstract

The complex dynamics in supramolecular structures of poly(p-phenylenes) with short ethylene oxide (EO) side chains (known as "hairy rods") have been studied by combining temperature and pressure dependent dielectric spectroscopy (DS) with different nuclear magnetic resonance (NMR) techniques. The system forms a periodic lattice of layers of the main chains separated by layers of the amorphous EO chains. Since the dipole moment is located on the EO side chain, DS is probing mainly the side-chain motions and only indirectly the backbone dynamics. On the other hand, the different NMR techniques are also sensitive to the backbone mobility and provide the molecular origin of the dynamic processes. Two dielectrically active processes exist, a "fast" β (which differs from the usual Johari-Goldstein β process found in homopolymers and low molecular weight glass-forming liquids) and a "slow" α process with the latter carrying most of the intensity. Comparison of the NMR and dielectric results identifies the outer EO units as solely responsible for the dielectric β process whereas both the short EO segments and the unfreezing of the internal backbone dynamics including bending motions contribute to the α process. The unfreezing of the backbone dynamics does not lead to the dissolution of the structure that only happens at even higher temperatures. Hairy rod molecules thus can serve as model systems which provide the means of studying the effect of confinement on the dynamics. In this respect, the effect of confinement is mainly on the temperature dependence of the α-process relaxation times. [ABSTRACT FROM AUTHOR]

Published
2002
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32. Real-Time Crystallization and Melting of Poly(n-octadecyl methacrylate) Induced by Temperature and Pressure: A Dielectric Spectroscopy Investigation

Author

Mierzwa, M. and Floudas, G.

Subjects
Polymethylmethacrylate -- Testing, Materials -- Dynamic testing, Crystallization -- Models, Business, Electronics, Electronics and electrical industries
Abstract

We have studied the crystallization and melting of poly(n-octadecyl methacrylate) (PNODMA) by performing temperature and pressure jump experiments from the melt to the final semicrystalline state. The evolution of the crystallization process is studied in real time by recording the changes in the dielectric spectrum. The single [Alpha] process in the melt upon crystallization looses intensity and a new slower [Alpha]' process appears, reflecting the dynamics of the restricted amorphous phase. The effect of pressure on increasing the crystallization temperature is stronger than the increase of the melt glass transition temperature, i.e. [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII]. The isothermal/isobaric crystallization experiments induced by T and P jumps give rise, respectively, to stretched exponential and to typical nucleation and growth kinetics of the Avrami type. The different crystallization kinetics induced by T and P reflect the `paradoxical' situation of increasing mobility with increasing pressure. From the equivalence of the dynamics we concluded that undercooling of 1 K corresponds to an overpressure of 20 MPa, i.e. [Delta]T/[Delta]P [approximately equals] 50 K/GPa.

Published
2001

35. Rheology and structure of entangled telechelic linear and star polyisoprene melts

Author

Van Ruymbeke, E. Vlassopoulos, D. Mierzwa, M. Pakula, T. Charalabidis, D. Pitsikalis, M. Hadjichristidis, N.

Abstract

We investigate the linear viscoelastic response of model telechelic linear and star (of varying functionality) polyisoprene melts with different molar masses above the entanglement limit in relation to their structure. We find that these systems self-assemble as a result of the strong dipolar interactions and form clusters that seem to depend primarily on the number of dipolar groups per star. The dynamics is rather complex, but some pertinent features are observed: the segmental dynamics is affected by the telechelic functionalization, especially for short arm lengths; this reflects the change of microstructure (and thus glass-transition temperature) with functionalization. The terminal relaxation is much slower compared to similar nonionic stars, reflecting the relaxation of clusters. Linear semitelechelic polymers (with only one end functionalized) aggregate in a star-like fashion. We further develop a tube model based on the time-marching algorithm for stars and linear chains, where we incorporate the association status of the chains via the dipolar interactions at each time step. The agreement of the predictions with the data, using two adjustable parameters (the average times when two dipolar pair remain associated or free, respectively), is remarkable and suggests design criteria for forming desired supramolecular assemblies. © 2010 American Chemical Society.

Published
2010

36. Dynamics of diblock co-polymers composed from a side-chain liquid-crystalline and a crystallizable block. A dielectric spectroscopy study

Author

Mierzwa, M., Floudas, G., and Wewerka, A.

Subjects
relaxation, behavior
Abstract

We have investigated the dynamics in two side-chain liquid crystalline derivatives of poly(norbornene diethylester) and their co-polymers with the semicrystalline block polyoctene by dielectric spectroscopy within the temperature range 170-433 K. The structure investigation revealed the formation of a nematic and a smectic A phase, respectively, in the Side-chain polymer liquid crystals (SC-PLC) homopolymers and the co-polymers with the shorter and longer spacers, respectively. Multiple relaxation processes were found in both the homopolymers and the co-polymers. The dynamics in the co-polymer with the longer spacer forming the smectic phase were reminiscent to the corresponding SC-PLC homopolymer, indicating strong microphase separation. However, in the co-polymer with the shorter spacer of the SC-PLC block forming the nematic phase, there was evidence for dynamic mixing between the dissimilar blocks which explains the reduced transition temperature of the SC-PLC block and the absence of crystallization of the polyoctene block. (C) 2002 Elsevier Science B.V. All rights reserved. Journal of Non-Crystalline Solids

Published
2002

37. Local and global dynamics of polylactides. A dielectric spectroscopy study

Author

Mierzwa, M., Floudas, G., Dorgan, J., Knauss, D., and Wegner, J.

Subjects
polyisoprene, acid), pressure, relaxation, rheology, dependence, fibers, polymers
Abstract

Polylactides (PLAs) are a family of degradable plastics having a component of the dipole moment both perpendicular and parallel to the polymer backbone (i.e. is a type-A polymer). We have studied the sub-glass. segmental and global chain dynamics in a series of fully amorphous samples having an L:D ratio of 80:20, with molecular weights in the range: 3.8 x 10(3) < M-n < 4.7 x 10(4). Finite size effects have been observed for both the segmental and the sub-glass process. The segmental mode was found to have a steeper temperature and pressure dependence compared to the longest normal mode in accord with findings from other type-A polymers. The molecular weight dependence of the longest normal mode relaxation times (tau similar to M-n(3.1)) reflects on the intermediate molecular weight regime (M-c similar to 6 x 10(3)) from Rouse to entangled chains. These findings are compared with the viscoelastic results on the same system. Agreement in the c, value of the WLF equation is found but the scaling of the normalized longest relaxation time derived from the rheological measurements shows a stronger than expected dependence on the molecular weight. (C) 2002 Elsevier Science B.V. All rights reserved. Journal of Non-Crystalline Solids

Published
2002

38. Rheology and Structure of Entangled Telechelic Linear and Star Polyisoprene Melts

Author

UCL - SST/IMCN - Institute of Condensed Matter and Nanosciences, Van Ruymbeke, Evelyne, Vlassopoulos, D., Mierzwa, M., Pakula, T., Charalabidis, D., Pitsikalis, M., Hadjichristidis, N., UCL - SST/IMCN - Institute of Condensed Matter and Nanosciences, Van Ruymbeke, Evelyne, Vlassopoulos, D., Mierzwa, M., Pakula, T., Charalabidis, D., Pitsikalis, M., and Hadjichristidis, N.

Abstract

We investigate the linear viscoelastic response of model telechelic linear and star (of varying functionality) polyisoprene melts with different molar masses above the entanglement limit in relation to their structure. We find that these systems self-assemble as a result of the strong dipolar interactions and form clusters that seem to depend primarily on the number of dipolar groups per star. The dynamics is rather complex, but some pertinent features are observed: the segmental dynamics is affected by the telechelic functionalization, especially for short arm lengths; this reflects the change of microstructure (and thus glass-transition temperature) with functionalization. The terminal relaxation is much slower compared to similar nonionic stars, reflecting the relaxation of clusters. Linear semitelechelic polymers (with only one end functionalized) aggregate in a star-like fashion. We further develop a tube model based on the time-marching algorithm for stars and linear chains, where we incorporate the association status or the chains via the dipolar interactions at each time step. The agreement of the predictions with the data, using two adjustable parameters (the average times when two dipolar pair remain associated or free, respectively), is remarkable and suggests design criteria for forming desired supramolecular assemblies.

Published
2010

46. Ordering effect on dynamics in glass-forming mixture of liquid crystals.

Author

Rzoska, Sylwester J., Mazur, Victor A., Mierzwa, M., Paluch, M., Rzoska, S. J., Zioło, J., and Maschke, U.

Abstract

Relaxation dynamics in glass-forming mixture of liquid crystals (E7) is studied by means of dielectric spectroscopy in the frequency range from 10−2 up to 109 Hz and over the temperature range from 200 to 373 K. We analyzed both the shape of relaxation spectra and temperature dependencies of behavior is observed in nematic phase. The dominant relaxation process exhibits nearly Debye form that depends on temperature in clearly the non- Arrhenius fashion. The dielectric spectra also show second distingue relaxation process which is related to α-relaxation. Additionally, we carried out the measurements of mechanical relaxation. As a result it was found that mechanical relaxation times correspond to dielectric α-relaxation times. [ABSTRACT FROM AUTHOR]

Published
2007
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47. Influence of Differences in Molecular structure on Behavior of and β Relaxation Processes in Diisooctyl Maleate.

Author

Rzoska, Sylwester J., Mazur, Victor A., Pawlus, S., Paluch, M., Mierzwa, M., Hensel-Bielowka, S., Kaminsha, E., Kaminski, K., Rzoska, S. J., and Maślanka, S.

Abstract

Dielectric relaxation measurements have been performed to study effect of the molecular structure on the primary and secondary relaxations in two materials with very similar structure: diisooctyl phthalate (DIOP) and diisooctyl maleate (DIOM). The dielectric spectra were measured over ten decades of frequency and a broad range of temperature. The results show that the temperature dependence of the α-relaxation times cannot be described by a single Vogel-Fulcher-Tammann equation and the temperature dependence of the β-relaxation times in the glassy state obey the Arrhenius law with different activation energies, i.e., EA/k = 4231 K and EA/k = 2917 K for DIOP and DIOM, respectively. Moreover, third relaxation process visible as an excess wing of the high frequency part of the α loss peak was identified in dielectric spectra of DIOM. [ABSTRACT FROM AUTHOR]

Published
2007
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