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Yan Ching Jean - One of the best experts on this subject based on the ideXlab platform.

  • Perspective of Positron Annihilation Spectroscopy in Polymers
    Macromolecules, 2013
    Co-Authors: Yan Ching Jean, J. David Van Horn, Wei-song Hung, Kuier-rarn Lee
    Abstract:

    Positron Annihilation Spectroscopy (PAS) is a novel method that provides molecular-level information about complex macromolecular structure in a manner different from, but complementary to, conventional physical and chemical methodology. This paper presents a perspective of PAS in polymeric systems covering 12 aspects: historical, spacial, spherical quantum model, anisotropic structure, voids, Positronium chemistry, time, Positron Annihilation lifetime Spectroscopy and data analysis, variable monoenergetic slow Positron beam techniques and depth profiling, elemental analysis, multidimensional instrumentation advances in PAS, and free volume and free-volume theories.

  • Applications of Positron Annihilation Spectroscopy to Life Science
    Defect and Diffusion Forum, 2012
    Co-Authors: H. Chen, J. David Van Horn, Yan Ching Jean
    Abstract:

    Positron Annihilation Spectroscopy (PAS) is a novel method that can provide molecular-level information about complex biological and macromolecular structure in a manner which is different, but complementary, to conventional medical and biochemical research methodology. Positron Annihilation lifetime Spectroscopy (PALS) and Doppler broadening energy Spectroscopy (DBES), coupled with a slow Positron beam have been extensively applied to the life science research recently. These techniques provide new information about the atomic and molecular level free-volume and void sizes, and their distributions 0.1 nm to a few nm, molecular bonding, structures at depth-layers, and phase transitions. This paper is to review recent research on Positron Annihilation Spectroscopy applied to the area of life science and also focus on current bioscience-related work in the Positron group at the University of MissouriKansas City (UMKC).

  • characterization of multilayer nanofiltration membranes using Positron Annihilation Spectroscopy
    Journal of Membrane Science, 2009
    Co-Authors: Kuo-lun Tung, Yan Ching Jean, Wei-song Hung, Dipankar Nanda, Kueir-rarn Lee, Juinyih Lai
    Abstract:

    Positron Annihilation Spectroscopy (PAS) coupled with a slow Positron beam was used to characterize in situ the layer structure and depth profile of the cavity size in thin film composite (TFC) polyamide nanofiltration (NF) membranes prepared by the interfacial polymerization method. Two techniques, using PAS coupled with a slow Positron beam of Doppler broadening energy spectra (DBES) and Positron Annihilation lifetime Spectroscopy (PALS) designed to reveal the layer structure and the cavity sizes contained in a multilayer thin film composite NF membrane, were assessed. To the best knowledge of the authors, a characterization of the depth profile of cavities in NF membranes using PAS coupled with a slow Positron beam has never been reported. The membranes selected have a composite structure containing three layers: a selective polyamide layer, a transition layer, and a porous support prepared by the phase inversion technique. Furthermore, the cavity size distribution in the selective top layer plays an important role in determining the performance of the NF membranes.

  • Investigation of Multilayer Pervaporation Membrane by Positron Annihilation Spectroscopy
    Macromolecules, 2008
    Co-Authors: Shu-hsien Huang, Yan Ching Jean, Wei-song Hung, Der-jang Liaw, Se-tsung Kao, Da-ming Wang, Manuel De Guzman, Kueir-rarn Lee
    Abstract:

    To investigate the polyamide thin-film composite membranes structure in regard to the variation in the free volume in thin-film composite membrane polyamide active layers, Positron Annihilation Spectroscopy (PAS) experiments using a slow Positron beam were performed. The correlation between the pervaporation performance and polyamide active layer free volume explored using the slow Positron beam technique was also investigated. The composite membranes were prepared via the interfacial polymerization reaction between ethylenediamine (EDA) and trimesoyl chloride (TMC) on the surface of a modified polyacrylonitrile (mPAN) membrane (EDA−TMC/mPAN). The variations in the S parameter at Positron incident energies of 0.5−2.5 keV indicate a decrease in the S parameter when the concentration of EDA in aqueous solution increased from 0.5 to 10 wt %. The Positron Annihilation took place at the surface of the polyamide active layer for the variations at low S parameters and high W parameters (Positron incident energy ...

  • Applications of Positron Annihilation Spectroscopy to polymeric membranes
    Desalination, 2008
    Co-Authors: Yan Ching Jean, H. Chen, Wei-song Hung, Guang Liu, Lakshmi Chakka, Mei-ling Cheng, Dipankar Nanda, Kuo-lun Tung, Shu-hsien Huang
    Abstract:

    Abstract Positron Annihilation Spectroscopy (PAS) coupled with a slow Positron beam has been used to study the freevolume depth profile (0–10 μm) in polymeric membrane systems prepared by the interfacial polymerization method. Doppler broadening energy parameters of Annihilation radiation vary as a function of the depth from the surface through multi-layers in polyamide asymmetric membranes prepared under different experimental parameters, such as the time, the temperature, and pH of membrane preparation process of interfacial polymerization. Three layer structures including a skin, a transition, and the porous layers in those asymmetric membrane systems are obtained. Positron Annihilation lifetime results provide additional information about free-volume size and distribution in nano- and micro-scale film membrane systems. PAS results are correlated with the pervaporation separation, flux and water wt% in permeate of 70% isopropanol aqueous solution and compared with the SEM images.

Wei-song Hung - One of the best experts on this subject based on the ideXlab platform.

  • Perspective of Positron Annihilation Spectroscopy in Polymers
    Macromolecules, 2013
    Co-Authors: Yan Ching Jean, J. David Van Horn, Wei-song Hung, Kuier-rarn Lee
    Abstract:

    Positron Annihilation Spectroscopy (PAS) is a novel method that provides molecular-level information about complex macromolecular structure in a manner different from, but complementary to, conventional physical and chemical methodology. This paper presents a perspective of PAS in polymeric systems covering 12 aspects: historical, spacial, spherical quantum model, anisotropic structure, voids, Positronium chemistry, time, Positron Annihilation lifetime Spectroscopy and data analysis, variable monoenergetic slow Positron beam techniques and depth profiling, elemental analysis, multidimensional instrumentation advances in PAS, and free volume and free-volume theories.

  • characterization of multilayer nanofiltration membranes using Positron Annihilation Spectroscopy
    Journal of Membrane Science, 2009
    Co-Authors: Kuo-lun Tung, Yan Ching Jean, Wei-song Hung, Dipankar Nanda, Kueir-rarn Lee, Juinyih Lai
    Abstract:

    Positron Annihilation Spectroscopy (PAS) coupled with a slow Positron beam was used to characterize in situ the layer structure and depth profile of the cavity size in thin film composite (TFC) polyamide nanofiltration (NF) membranes prepared by the interfacial polymerization method. Two techniques, using PAS coupled with a slow Positron beam of Doppler broadening energy spectra (DBES) and Positron Annihilation lifetime Spectroscopy (PALS) designed to reveal the layer structure and the cavity sizes contained in a multilayer thin film composite NF membrane, were assessed. To the best knowledge of the authors, a characterization of the depth profile of cavities in NF membranes using PAS coupled with a slow Positron beam has never been reported. The membranes selected have a composite structure containing three layers: a selective polyamide layer, a transition layer, and a porous support prepared by the phase inversion technique. Furthermore, the cavity size distribution in the selective top layer plays an important role in determining the performance of the NF membranes.

  • Investigation of Multilayer Pervaporation Membrane by Positron Annihilation Spectroscopy
    Macromolecules, 2008
    Co-Authors: Shu-hsien Huang, Yan Ching Jean, Wei-song Hung, Der-jang Liaw, Se-tsung Kao, Da-ming Wang, Manuel De Guzman, Kueir-rarn Lee
    Abstract:

    To investigate the polyamide thin-film composite membranes structure in regard to the variation in the free volume in thin-film composite membrane polyamide active layers, Positron Annihilation Spectroscopy (PAS) experiments using a slow Positron beam were performed. The correlation between the pervaporation performance and polyamide active layer free volume explored using the slow Positron beam technique was also investigated. The composite membranes were prepared via the interfacial polymerization reaction between ethylenediamine (EDA) and trimesoyl chloride (TMC) on the surface of a modified polyacrylonitrile (mPAN) membrane (EDA−TMC/mPAN). The variations in the S parameter at Positron incident energies of 0.5−2.5 keV indicate a decrease in the S parameter when the concentration of EDA in aqueous solution increased from 0.5 to 10 wt %. The Positron Annihilation took place at the surface of the polyamide active layer for the variations at low S parameters and high W parameters (Positron incident energy ...

  • Applications of Positron Annihilation Spectroscopy to polymeric membranes
    Desalination, 2008
    Co-Authors: Yan Ching Jean, H. Chen, Wei-song Hung, Guang Liu, Lakshmi Chakka, Mei-ling Cheng, Dipankar Nanda, Kuo-lun Tung, Shu-hsien Huang
    Abstract:

    Abstract Positron Annihilation Spectroscopy (PAS) coupled with a slow Positron beam has been used to study the freevolume depth profile (0–10 μm) in polymeric membrane systems prepared by the interfacial polymerization method. Doppler broadening energy parameters of Annihilation radiation vary as a function of the depth from the surface through multi-layers in polyamide asymmetric membranes prepared under different experimental parameters, such as the time, the temperature, and pH of membrane preparation process of interfacial polymerization. Three layer structures including a skin, a transition, and the porous layers in those asymmetric membrane systems are obtained. Positron Annihilation lifetime results provide additional information about free-volume size and distribution in nano- and micro-scale film membrane systems. PAS results are correlated with the pervaporation separation, flux and water wt% in permeate of 70% isopropanol aqueous solution and compared with the SEM images.

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

  • Applications of Positron Annihilation Spectroscopy to Life Science
    Defect and Diffusion Forum, 2012
    Co-Authors: H. Chen, J. David Van Horn, Yan Ching Jean
    Abstract:

    Positron Annihilation Spectroscopy (PAS) is a novel method that can provide molecular-level information about complex biological and macromolecular structure in a manner which is different, but complementary, to conventional medical and biochemical research methodology. Positron Annihilation lifetime Spectroscopy (PALS) and Doppler broadening energy Spectroscopy (DBES), coupled with a slow Positron beam have been extensively applied to the life science research recently. These techniques provide new information about the atomic and molecular level free-volume and void sizes, and their distributions 0.1 nm to a few nm, molecular bonding, structures at depth-layers, and phase transitions. This paper is to review recent research on Positron Annihilation Spectroscopy applied to the area of life science and also focus on current bioscience-related work in the Positron group at the University of MissouriKansas City (UMKC).

  • Applications of Positron Annihilation Spectroscopy to polymeric membranes
    Desalination, 2008
    Co-Authors: Yan Ching Jean, H. Chen, Wei-song Hung, Guang Liu, Lakshmi Chakka, Mei-ling Cheng, Dipankar Nanda, Kuo-lun Tung, Shu-hsien Huang
    Abstract:

    Abstract Positron Annihilation Spectroscopy (PAS) coupled with a slow Positron beam has been used to study the freevolume depth profile (0–10 μm) in polymeric membrane systems prepared by the interfacial polymerization method. Doppler broadening energy parameters of Annihilation radiation vary as a function of the depth from the surface through multi-layers in polyamide asymmetric membranes prepared under different experimental parameters, such as the time, the temperature, and pH of membrane preparation process of interfacial polymerization. Three layer structures including a skin, a transition, and the porous layers in those asymmetric membrane systems are obtained. Positron Annihilation lifetime results provide additional information about free-volume size and distribution in nano- and micro-scale film membrane systems. PAS results are correlated with the pervaporation separation, flux and water wt% in permeate of 70% isopropanol aqueous solution and compared with the SEM images.

  • Life science research using Positron Annihilation Spectroscopy: UV-irradiated mouse skin
    Radiation Physics and Chemistry, 2007
    Co-Authors: Yan Ching Jean, H. Chen, Guang Liu, Joseph E. Gadzia
    Abstract:

    Abstract Positron Annihilation Spectroscopy (PAS) is applied to study mouse skin under different UV irradiations as a function of Positron incident energy (0–30 keV). Significant variations in the depth profile of S parameter are observed in a period of hours and of days for UVA and UVB exposures, respectively. The high sensitivity of Positron Annihilation signals responding to UV irradiation shows that PAS may be developed as a new noninvasive technique for the detection of molecular damage in life science research.

  • Early stage of deterioration in polymeric coatings detected by Positron Annihilation Spectroscopy
    Progress in Organic Coatings, 2005
    Co-Authors: Yan Ching Jean, H. Chen, R. Zhang, Junjie Zhang
    Abstract:

    In polymeric coating systems, Positron Annihilation Spectroscopy has shown sensitivity in detecting the early stage of deterioration due to weathering, specially, in probing a specific location or depth of coatings from the surface through interfaces and the bulk. Existing extensive experimental Positron data show that Positron Annihilation signals respond quantitatively to the deterioration process due to weathering. Now, it is possible to detect the very early stage of coating deterioration at the atomic and molecular scale by using Positrons, typically in days as compared to years by conventional methods. This paper summarizes recent Positron studies in polymeric coatings. Correlations between Positron data and a variety of chemical, physical and engineering data from ESR, AFM, cross-link density, gloss, and cyclic loading are presented. A proposed application of Positron Annihilation Spectroscopy as a real field inspection tool to detect coating deterioration of bridges is presented.

  • Positron Annihilation Spectroscopy for surface and interface studies in nanoscale polymeric films.
    Spectrochimica acta. Part A Molecular and biomolecular spectroscopy, 2005
    Co-Authors: Yan Ching Jean, H. Chen, Junjie Zhang, Guang Liu
    Abstract:

    Positron Annihilation Spectroscopy (PAS), coupled with a variable mono-energetic Positron beam, has been used to investigate surface and interfacial properties in thin polymeric films. Free-volume properties have been measured from ortho-Positronium (o-Ps) lifetime and the S parameter of Doppler broadening of energy spectra from Annihilation radiation as a function of the depth and of the temperature in thin polymeric films. Depth profiles of glass transition temperature and nanoscale layered structures in polystyrene (PS) thin films on the Si substrate are presented.

A Kawasuso - One of the best experts on this subject based on the ideXlab platform.

  • vacancy induced ferromagnetism in zno probed by spin polarized Positron Annihilation Spectroscopy
    Applied Physics Letters, 2017
    Co-Authors: M Maekawa, Hiroshi Abe, A Miyashita, Seiji Sakai, Shunya Yamamoto, A Kawasuso
    Abstract:

    We investigated the ferromagnetism of ZnO induced by oxygen implantation by using spin-polarized Positron Annihilation Spectroscopy together with magnetization measurements. The magnetization measurements showed the appearance of ferromagnetism after oxygen implantation and its disappearance during post-implantation annealing at temperatures above 573 K. The Doppler broadening of Annihilation radiation (DBAR) spectrum showed asymmetry upon field reversal after oxygen implantation. The obtained differential DBAR spectrum between positive and negative magnetic fields was well-explained with a theoretical calculation considering zinc vacancies. The disappearance of the field-reversal asymmetry of the DBAR spectrum as a result of annealing agreed with the observations of ferromagnetism by magnetization measurements. These results suggest the radiation-induced zinc vacancies to be the source of the observed ferromagnetism of ZnO.

Guang Liu - One of the best experts on this subject based on the ideXlab platform.

  • Applications of Positron Annihilation Spectroscopy to polymeric membranes
    Desalination, 2008
    Co-Authors: Yan Ching Jean, H. Chen, Wei-song Hung, Guang Liu, Lakshmi Chakka, Mei-ling Cheng, Dipankar Nanda, Kuo-lun Tung, Shu-hsien Huang
    Abstract:

    Abstract Positron Annihilation Spectroscopy (PAS) coupled with a slow Positron beam has been used to study the freevolume depth profile (0–10 μm) in polymeric membrane systems prepared by the interfacial polymerization method. Doppler broadening energy parameters of Annihilation radiation vary as a function of the depth from the surface through multi-layers in polyamide asymmetric membranes prepared under different experimental parameters, such as the time, the temperature, and pH of membrane preparation process of interfacial polymerization. Three layer structures including a skin, a transition, and the porous layers in those asymmetric membrane systems are obtained. Positron Annihilation lifetime results provide additional information about free-volume size and distribution in nano- and micro-scale film membrane systems. PAS results are correlated with the pervaporation separation, flux and water wt% in permeate of 70% isopropanol aqueous solution and compared with the SEM images.

  • Life science research using Positron Annihilation Spectroscopy: UV-irradiated mouse skin
    Radiation Physics and Chemistry, 2007
    Co-Authors: Yan Ching Jean, H. Chen, Guang Liu, Joseph E. Gadzia
    Abstract:

    Abstract Positron Annihilation Spectroscopy (PAS) is applied to study mouse skin under different UV irradiations as a function of Positron incident energy (0–30 keV). Significant variations in the depth profile of S parameter are observed in a period of hours and of days for UVA and UVB exposures, respectively. The high sensitivity of Positron Annihilation signals responding to UV irradiation shows that PAS may be developed as a new noninvasive technique for the detection of molecular damage in life science research.

  • Positron Annihilation Spectroscopy for surface and interface studies in nanoscale polymeric films.
    Spectrochimica acta. Part A Molecular and biomolecular spectroscopy, 2005
    Co-Authors: Yan Ching Jean, H. Chen, Junjie Zhang, Guang Liu
    Abstract:

    Positron Annihilation Spectroscopy (PAS), coupled with a variable mono-energetic Positron beam, has been used to investigate surface and interfacial properties in thin polymeric films. Free-volume properties have been measured from ortho-Positronium (o-Ps) lifetime and the S parameter of Doppler broadening of energy spectra from Annihilation radiation as a function of the depth and of the temperature in thin polymeric films. Depth profiles of glass transition temperature and nanoscale layered structures in polystyrene (PS) thin films on the Si substrate are presented.