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positron Spectroscopy of Free Volume in Poly(vinylidene fluoride) after Helium Ions Irradiation

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Chinese Journal of Polymer Science 2019年第5期37卷 527-534页

作者： Jin-Zhe Lyu Roman Laptev Natalya Dubrova Division for Experimental Physics School of Nuclear Science & EngineeringNational Research Tomsk Polytechnic University

Free volume is an extremely important intrinsic defect in polymers. Structurally, free volume is the randomly distributed holes in the polymer molecular chain segments. In proton exchange membrane fuel cells, free volume is also the space needed for the directional conduction of protons. Irradiation by α particles to grafting sulfonated poly(vinylidene fluoride)(PVDF) is one of the methods to produce proton exchange membrane with good proton channel rate. positron annihilation lifetime spectroscopy was used to study the free volume size at different absorbed dose levels from 0.13 MGy to 0.65 MGy. Measurement method of positron annihilation lifetime spectroscopy for PVDF based on ^(44) Ti positron source was developed. For low dose irradiation at 0.26 MGy, a decrease in free volume and practically unchanged crystallinity were observed. Further increase of absorbed dose range from 0.26 MGy to 0.39 MGy led to an increasing crystallinity with the same free volume level. For the absorbed dose from 0.39 MGy to 0.65 MGy, crystallinity was decreased but free volume remained almost constant.

关键词： positron annihilation Free volume XRD Poly(vinylidene fluoride) Helium ions Connection Degradation

positron Impact Transitions of Atomic Sodium

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Chinese Physics Letters 2011年第9期28卷 116-119页

作者： CHENG Yong-Jun ZHOU Ya-Jun Natural Science Research Center The Academy of Fundamental and Interdisciplinary ScienceHarbin Institute of TechnologyHarbin 150080

We present a new investigation of elastic and inelastic positron-sodium scattering by using the coupled-channel optical method(CCO)at an incident energy region of 2–100 *** ionization continuum and positronium formation channels have been included via a complex equivalent-local optical *** present calculations are compared with available theoretical data and our investigation indicates that the inclusion of ionization and Ps-formation channels in the present calculations has a significant effect on the cross sections of elastic and inelastic positron-sodium scattering at lower energies.

关键词： potential Transition positron

positron-impact ionisation of atomic hydrogen in the presence of a bichromatic laser field

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Chinese Physics B 2010年第11期19卷 347-350页

作者：娄俊李书民 Department of Modern Physics University of Science and Technology of China Institut fr Theoretische Physik Universitt HeidelbergPhilosophenweg 1669120 HeidelbergGermany

The positron impact-ionisation of atomic hydrogen in the presence of a linearly polarised bichromatic field is investigated in the first Born approximation. The field is composed of a fundamental frequency and its second harmonic. The state of positron in the field is described by the Volkov wavefunction, and the continuum state of the ejected electron is described by the Coulomb-Volkov wavefunction. The dressed ground state of target is a first order time-dependent perturbative wavefunction. The triple differential cross sections and their dependencies on laser field parameters are discussed and compared with the results modified by a monochromatic field. Numerical results show that the coherent phase control is significant and the laser-assisted ionisation cross sections caused by positron and electron are different.

关键词： bichromatic laser field positron impact-ionisation

Investigation of the free volume and ionic conducting mechanism of poly(ethylene oxide)-LiClO_4 polymeric electrolyte by positron annihilating lifetime spectroscopy

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Chinese Physics B 2012年第10期21卷 478-484页

作者：龚静宫振丽闫晓丽高舒张忠良王波 School of Physics and Key Laboratory of Nuclear Solid State Physics Wuhan University

The positron annihilation lifetime and ionic conductivity are each measured as a function of organophilic rectorite（OREC） content and temperature in a range from 160 K to 300 *** to the variation of ortho-positronium（o-Ps） lifetime with temperature,the glassy transition temperature is *** continuous maximum entropy lifetime（MELT） analysis clearly shows that the OREC and temperature have important effects on o-Ps lifetime and free volume *** experimental results show that the temperature dependence of ionic conductivity obeys the Vogel-Tammann-Fulcher（VTF） and Williams-Landel-Ferry（WLF） equations,implying a free-volume transport mechanism.A linear least-squares procedure is used to evaluate the apparent activation energy related to the ionic transport in the VTF equation and several important parameters in the WLF *** is worthwhile to notice that a direct linear relationship between the ionic conductivity and free volume fraction is established using the WLF equation based on the free volume theory for nanocomposite electrolyte,which indicates that the segmental chain migration and ionic migration and diffusion could be explained by the free volume theory.

关键词： positron free volume polymeric electrolyte ionic conduction

positron emission tomography/computerized tomography in the evaluation of primary non-Hodgkin's lymphoma of prostate

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World Journal of Gastroenterology 2013年第39期19卷 6699-6702页

作者： Bo Pan Jian-Kui Han Shi-Cun Wang Ao Xu PET/CT Center Qilu Hospitalthe First Affiliated Hospital of Shandong University PET/CT Center Affiliated Anhui Provincial Hospital of Anhui Medical University Department of Pathology Affiliated Anhui Provincial Hospital of Anhui Medical University

Primary malignant lymphoma of the prostate is exceedingly *** we report a case of a 65-year-old man who presented with increased urinary frequency,urinary urgency,and urinary incontinence for two *** prostatic hypertrophy was suspected at primary *** revealed a hypoechoic lesion of the *** total serum prostate-specific antigen was within normal *** emission tomography/computerized tomography(PET/CT)showed a hypermetabolic prostatic *** biopsy was consistent with a non-germinal center diffuse large B cell *** was complete remission of the prostatic lesion following six cycles of chemotherapy as shown on the second PET/CT imaging.18F-fluoro-deoxy glucose PET/CT is not only a complement to conventional imaging,but also plays a significant role in the diagnosis and evaluation of treatment response of prostatic lymphoma.

关键词： Fluoro-Deoxy-Glucose positron emission tomography/computerized tomography Non-Hodgkin’s lymphoma Prostatic lymphoma Evaluation

Elastic and inelastic positron-helium scattering

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Chinese Physics B 2010年第6期19卷 283-288页

作者：程勇军周雅君 Natural Science Research Center the Academy of Fundamental and Interdisciplinary ScienceHarbin Institute of Technology

Elastic and inelastic positron-helium scatterings have been investigated with the coupled-channel optical method （CCO）. Ionization continuum and positronium formation channels are included via a complex equivalent-local optical potential. Calculations are reported of cross sections of elastic scattering, total excitation and n=2, 3, and 4 excitations of ground-state helium for incident energies from 30 eV to 400 eV. The present calculation shows that the ionization and Ps-formation channels significantly affect the cross sections of elastic and inelastic positron-helium scatterings.

关键词： positron helium elastic scattering excitation

Resonance phenomena and threshold features in positron-helium scattering

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Chinese Physics B 2012年第5期21卷 179-184页

作者：于荣梅程勇军王旸周雅君 The Academy of Fundamental and Interdisciplinary Sciences Harbin Institute of Technology

Investigations of resonances and threshold behaviors in positron-helium scattering have been made using the momentum-space coupled-channels optical *** positronium formation channels are considered via an equivalent-local complex *** s-wave resonances and the Wigner cusp feature at the positronium（n = 1） formation threshold are compared with the previous *** p-and the d-wave resonances and a Wigner cusp feature at the positronium（n = 2） formation threshold are reported for the first time.

关键词： positron helium resonance

Coupled-channel optical calculation for positron-lithium scattering

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Chinese Physics B 2012年第5期21卷 185-189页

作者：刘芳程勇军周雅君 Natural Science Research Center Academy of Fundamental and Interdisciplinary ScienceHarbin Institute of Technology

positron scattering with atomic lithium is investigated by using a coupled-channel optical *** ionization continuum and positronium formation channels are taken into account via a complex equivalent-local optical *** positronium formation cross sections and the ionization cross sections,as well as the total scattering cross sections,are reported at energies above 3 eV and compared with available experimental and theoretical data.

关键词： positron lithium positronium ionization

Effects of thermal aging on Fe ion-irradiated Fe–0.6%Cu alloy investigated by positron annihilation

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Nuclear Science and Techniques 2017年第2期28卷 8-11页

作者： Yuan-Chao Hu Xing-Zhong Cao Peng Zhang Hidetsugu Tsuchida Qiu Xu Shuo-Xue Jin Er-Yang Lu Yu-Xiao Li Run-Sheng Yu Bao-Yi Wang Long Wei Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China College of Physical Engineering Zhengzhou UniversityZhengzhou 450001 China Quantum Science and Engineering Center Kyoto UniversityUji 6110011 Japan Research Reactor Institute Kyoto UniversityOsaka 5900494 Japan

Thermal aging effects on surface of 2.5 Me V Fe ion-irradiated Fe–0.6%Cu alloy were investigated using positron annihilation techniques. The samples were irradiated at 573 K to a dose of 0.1 dpa. Their thermal aging was performed at 573 K for 5, 50 and 100 h. From the results of Doppler broadening measurement, an obvious trough could be seen in near-surface region from the S parameters and inflection point form at S–W curves. This indicates changes in the annihilation mechanism of positrons in surface region after thermal aging. Coincident Doppler broadening indicates that the density of Cu precipitates in the thermal aged samples decreased, due to recovery of the vacancies.

关键词： Fe–Cu alloy positron annihilation Irradiation Thermal aging