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Nonlinear Propagation of Positron-Acoustic Periodic Travelling Waves in a Magnetoplasma with Superthermal Electrons and Positrons
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作者 E.F.EL-Shamy 《Chinese Physics Letters》 SCIE CAS CSCD 2017年第6期70-74,共5页
The nonlinear propagation of positron acoustic periodic (PAP) travelling waves in a magnetoplasma composed of dynamic cold positrons, superthermal kappa distributed hot positrons and electrons, and stationary positi... The nonlinear propagation of positron acoustic periodic (PAP) travelling waves in a magnetoplasma composed of dynamic cold positrons, superthermal kappa distributed hot positrons and electrons, and stationary positive ions is examined. The reductive perturbation technique is employed to derive a nonlinear Zakharov Kuznetsov equation that governs the essential features of nonlinear PAP travelling waves. Moreover, the bifurcation theory is used to investigate the propagation of nonlinear PAP periodic travelling wave solutions. It is found that kappa distributed hot positrons and electrons provide only the possibility of existence of nonlinear compressive PAP travelling waves. It is observed that the superthermality of hot positrons, the concentrations of superthermal electrons and positrons, the positron cyclotron frequency, the direction cosines of wave vector k along the z-axis, and the concentration of ions play pivotal roles in the nonlinear propagation of PAP travelling waves. Tile present investigation may be used to understand the formation of PAP structures in the space and laboratory plasmas with superthermal hot positrons and electrons. 展开更多
关键词 Nonlinear Propagation of Positron-Acoustic Periodic Travelling Waves in a Magnetoplasma with Superthermal Electrons and positrons
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Gas Permeability and Free Volume Hole Properties of Interpenetrating Polymer Network Studied by Positrons
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作者 QI Ning GONG Wei +3 位作者 WANG Zhifen WANG Bo YANG Yurun HU Chunpu 《Wuhan University Journal of Natural Sciences》 CAS 2007年第2期271-274,共4页
A series of polyurethane/epoxy resin interpenetrating polymer networks (PU/ER IPN) were studied by positron annihilation lifetime spectroscopy (PALS). The effects of epoxy resin type and content on the free volume... A series of polyurethane/epoxy resin interpenetrating polymer networks (PU/ER IPN) were studied by positron annihilation lifetime spectroscopy (PALS). The effects of epoxy resin type and content on the free volume properties in IPN were investigated. We found that in PU/ER IPN, the free volume hole size and fractional free volume showed a negative deviation due to closer segmental chain packing through some chemical bonding between PU and epoxy resin. Direct relationship between the gas permeability and the free volume has been established based on the free volume theory. Experimental results revealed that the free volume plays an important role in determining the gas diffusion and permeability. 展开更多
关键词 interpenetrating polymer network positron annihilation free volume gas permeability
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Solitary kinetic Alfvén waves in a dense electron–positron–ion plasma with degenerate electrons and positrons
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作者 Monzurul K AHMED Om P SAH 《Plasma Science and Technology》 SCIE EI CAS CSCD 2017年第12期42-49,共8页
Through the use of a reductive perturbation technique, solitary kinetic Alfvén waves(KAWs) are investigated in a low but finite b(particle-to-magnetic pressure ratio) dense electron–positron–ion plasma wher... Through the use of a reductive perturbation technique, solitary kinetic Alfvén waves(KAWs) are investigated in a low but finite b(particle-to-magnetic pressure ratio) dense electron–positron–ion plasma where electrons and positrons are degenerate. The degenerate plasma model considered here permits the existence of sub-Alfvénic compressive solitary KAWs. The influence of r(equilibrium positron-to-ion density ratio), sF(electron-to-positron Fermi temperature ratio), b and obliqueness parameter lzon various characteristics of solitary KAWs are examined through numerical plots. We have shown that there exists a critical value of lzat which a soliton width attains its maximum value which decreases with an increase in r and sF.It is also found that solitons with a higher energy propagate more obliquely in the direction of an ambient magnetic field. The results of the present investigation may be useful for understanding low frequency nonlinear electromagnetic wave propagation in magnetized electron–positron–ion plasmas in dense stars. Specifically, the relevance of our investigation to a pulsar magnetosphere is emphasized. 展开更多
关键词 kinetic Alfvén waves solitons electron–positron–ion plasma degenerate plasma Thomas–Fermi approximation
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Dark Matter Particle Explorer observations of high-energy cosmic ray electrons plus positrons and their physical implications 被引量:5
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作者 Qiang Yuan Lei Feng 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS CSCD 2018年第10期2-13,共12页
The DArk Matter Particle Explorer (DAMPE) is a satellite-borne, high-energy particle and 3,-ray detector, which is dedicated to indirectly detecting particle dark matter and studying high-energy astrophysics. The fi... The DArk Matter Particle Explorer (DAMPE) is a satellite-borne, high-energy particle and 3,-ray detector, which is dedicated to indirectly detecting particle dark matter and studying high-energy astrophysics. The first results about precise measurement of the cosmic ray electron plus positron spectrum between 25 GeV and 4.6 TeV were published recently. The DAMPE spectrum reveals an interesting spectral softening arount 0.9 TeV and a tentative peak around 1.4 TeV. These results have inspired extensive discussion. The detector of DAMPE, the data analysis, and the first results are introduced. In particular, the physical interpretations of the DAMPE data are reviewed. 展开更多
关键词 dark matter cosmic rays electrons plus positrons PULSARS
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Feasibility study of a LYSO‑SiPM‑based prototype for hybrid Compton and PET imaging
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作者 Hai‑Hao Wang Yu‑Cun Hou +4 位作者 Jian‑Lang Hua Zi‑Quan Yuan Chen‑Xi Li Run‑Ze Liao Jian‑Yong Jiang 《Nuclear Science and Techniques》 2026年第1期80-93,共14页
We present a prototype for hybrid Compton and positron emission tomography(PET)imaging aimed at enhancing data utilization and enabling concurrent imaging of multiple radiopharmaceuticals.The prototype comprises two d... We present a prototype for hybrid Compton and positron emission tomography(PET)imaging aimed at enhancing data utilization and enabling concurrent imaging of multiple radiopharmaceuticals.The prototype comprises two detectors that utilize LYSO-SiPM and were available in our laboratory.One detector consists of a 50×50 array of LYSO crystals,each measuring 0.9mm×0.9mm×10mm with 1 mm pitches,whereas the other detector comprises a 25×25 array of LYSO crystals,each measuring 1.9mm×1.9mm×10mm with 2 mm pitches.These detectors are mounted on a rotational stage,which enables them to function as either a Compton camera or a PET detector pair.The 64-channel signals from the SiPMs of each detector are processed through a capacitive multiplexing circuit to yield four position-weighted outputs.Distinct energy windows were used to discriminate Compton events from PET events.Energy resolution and energy-channel relationships were calibrated via multiple sources.The measured average energy resolutions(full widths at half maximum,FWHMs)for the detectors at 511 keV were 17.5%and 15.2%,respectively.The initial experimental results indicate an angular resolution(FWHM)of 8.6◦for the system in Compton imaging mode.A V-shaped tube injected with 18 F solution was clearly reconstructed,which further verified the imaging capabilities of the system in Compton imaging mode.The results of simulation and experimental imaging studies show that the system can detect tumors as small as 1 mm in diameter when working in PET imaging mode.Mouse bone PET imaging was successfully conducted,with the results matching well with the corresponding CT images.This technology holds great potential for advancing the development of physiological function modalities. 展开更多
关键词 Positron emission tomography(PET) Compton camera Image reconstruction
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Identification of Defects in Neutron-transmutation-doped Si by Positrons 被引量:1
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作者 孟祥提 《Science China Mathematics》 SCIE 1994年第10期1262-1271,共10页
The V and V2-type defects are dominant in NTD Si irradiated with 6×1016, 3.6×1017 and 1.2× 1018 neutrons/cm2. Two distinct annealing stages of V-type defects exist: one at about 200℃ due to the anneali... The V and V2-type defects are dominant in NTD Si irradiated with 6×1016, 3.6×1017 and 1.2× 1018 neutrons/cm2. Two distinct annealing stages of V-type defects exist: one at about 200℃ due to the annealing-out of P-V and (V2-O)- complexes; the other at about 500℃ due to the annealing-out of (V2-O)0 complexes. There are two annealing stages for V2-type defects at 150-200℃ and at about 600℃ . The former is due to interstitial silicon atoms approaching divacancies, which are trapped by oxygen atoms or combined with each other into V4; the latter is due to annealing-out of V20 and V3-0 complexes. The intensity of the second-dary V2-type defects is highly dependent on the neutron dose. V4 with the intensities smaller than 3.2% appears in NTD Si irradiated with two higher neutron doses and annealed in between 125-200℃ and in between 400-600℃ . Above 700℃ dislocations and/or V-type defects are formed. The specific trapping rates for V- V2- and V4-type defects are calculated to be 5.9×1014/s, 2.5×1015/s, and 1.24×1015/s, respectively. 展开更多
关键词 POSITRON LIFETIME spectroscopy NEUTRON RADIATION silicon.
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Multisensory mechanisms of gait and balance in Parkinson’s disease:an integrative review 被引量:1
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作者 Stiven Roytman Rebecca Paalanen +4 位作者 Giulia Carli Uros Marusic Prabesh Kanel Teus van Laar Nico I.Bohnen 《Neural Regeneration Research》 SCIE CAS 2025年第1期82-92,共11页
Understanding the neural underpinning of human gait and balance is one of the most pertinent challenges for 21st-century translational neuroscience due to the profound impact that falls and mobility disturbances have ... Understanding the neural underpinning of human gait and balance is one of the most pertinent challenges for 21st-century translational neuroscience due to the profound impact that falls and mobility disturbances have on our aging population.Posture and gait control does not happen automatically,as previously believed,but rather requires continuous involvement of central nervous mechanisms.To effectively exert control over the body,the brain must integrate multiple streams of sensory information,including visual,vestibular,and somatosensory signals.The mechanisms which underpin the integration of these multisensory signals are the principal topic of the present work.Existing multisensory integration theories focus on how failure of cognitive processes thought to be involved in multisensory integration leads to falls in older adults.Insufficient emphasis,however,has been placed on specific contributions of individual sensory modalities to multisensory integration processes and cross-modal interactions that occur between the sensory modalities in relation to gait and balance.In the present work,we review the contributions of somatosensory,visual,and vestibular modalities,along with their multisensory intersections to gait and balance in older adults and patients with Parkinson’s disease.We also review evidence of vestibular contributions to multisensory temporal binding windows,previously shown to be highly pertinent to fall risk in older adults.Lastly,we relate multisensory vestibular mechanisms to potential neural substrates,both at the level of neurobiology(concerning positron emission tomography imaging)and at the level of electrophysiology(concerning electroencephalography).We hope that this integrative review,drawing influence across multiple subdisciplines of neuroscience,paves the way for novel research directions and therapeutic neuromodulatory approaches,to improve the lives of older adults and patients with neurodegenerative diseases. 展开更多
关键词 aging BALANCE encephalography functional magnetic resonance imaging GAIT multisensory integration Parkinson’s disease positron emission tomography SOMATOSENSORY VESTIBULAR visual
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Recent progress in the applications of presynaptic dopaminergic positron emission tomography imaging in parkinsonism 被引量:1
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作者 Yujie Yang Xinyi Li +7 位作者 Jiaying Lu Jingjie Ge Mingjia Chen Ruixin Yao Mei Tian Jian Wang Fengtao Liu Chuantao Zuo 《Neural Regeneration Research》 SCIE CAS 2025年第1期93-106,共14页
Nowadays,presynaptic dopaminergic positron emission tomography,which assesses deficiencies in dopamine synthesis,storage,and transport,is widely utilized for early diagnosis and differential diagnosis of parkinsonism.... Nowadays,presynaptic dopaminergic positron emission tomography,which assesses deficiencies in dopamine synthesis,storage,and transport,is widely utilized for early diagnosis and differential diagnosis of parkinsonism.This review provides a comprehensive summary of the latest developments in the application of presynaptic dopaminergic positron emission tomography imaging in disorders that manifest parkinsonism.We conducted a thorough literature search using reputable databases such as PubMed and Web of Science.Selection criteria involved identifying peer-reviewed articles published within the last 5 years,with emphasis on their relevance to clinical applications.The findings from these studies highlight that presynaptic dopaminergic positron emission tomography has demonstrated potential not only in diagnosing and differentiating various Parkinsonian conditions but also in assessing disease severity and predicting prognosis.Moreover,when employed in conjunction with other imaging modalities and advanced analytical methods,presynaptic dopaminergic positron emission tomography has been validated as a reliable in vivo biomarker.This validation extends to screening and exploring potential neuropathological mechanisms associated with dopaminergic depletion.In summary,the insights gained from interpreting these studies are crucial for enhancing the effectiveness of preclinical investigations and clinical trials,ultimately advancing toward the goals of neuroregeneration in parkinsonian disorders. 展开更多
关键词 aromatic amino acid decarboxylase brain imaging dopamine transporter Parkinson’s disease PARKINSONISM positron emission tomography presynaptic dopaminergic function vesicle monoamine transporter type 2
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Progress in the application of fludeoxyglucose positron emission tomography computed tomography in biliary tract cancer 被引量:1
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作者 Jia-Xin Yin Xin Fan +2 位作者 Qiao-Liang Chen Jing Chen Jian He 《World Journal of Hepatology》 2025年第5期32-44,共13页
Biliary tract cancer(BTC)is a group of heterogeneous sporadic diseases,including intrahepatic,hilar,and distal cholangiocarcinoma,as well as gallbladder cancer.BTC is characterized by high invasiveness and extremely p... Biliary tract cancer(BTC)is a group of heterogeneous sporadic diseases,including intrahepatic,hilar,and distal cholangiocarcinoma,as well as gallbladder cancer.BTC is characterized by high invasiveness and extremely poor prognosis,with a global increased incidence due to intrahepatic cholangiocarcinoma(ICC).The 18Ffludeoxyglucose positron emission tomography(PET)computed tomography(18F-FDG PET/CT)combines glucose metabolic information(reflecting the glycolytic activity of tumor cells)with anatomical structure to assess tumor metabolic heterogeneity,systemic metastasis,and molecular characteristics noninvasively,overcoming the limitations of traditional imaging in the detection of micrometastases and recurrent lesions.18F-FDG PET/CT offers critical insights in clinical staging,therapeutic evaluation,and prognostic prediction of BTC.This article reviews research progress in this field over the past decade,with a particular focus on the advances made in the last 3 years,which have not been adequately summarized and recognized.The research paradigm in this field is shifting from qualitative to quantitative studies,and there have been significant breakthroughs in using 18F-FDG PET/CT metabolic information to predict gene expression in ICC.Radiomics and deep learning techniques have been applied to ICC for prognostic prediction and differential diagnosis.Additionally,PET/magnetic resonance imaging is increasingly demonstrating its value in this field. 展开更多
关键词 Biliary tract cancer Positron radiopharmaceuticals Fluorodeoxyglucose positron emission tomography Radiomics Positron emission tomography computed tomography Positron emission tomography magnetic resonance imaging
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Gamma-induced positron beam generation at SLEGS 被引量:1
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作者 Sheng Jin Zi-Rui Hao +8 位作者 Long-Xiang Liu Kai-Jie Chen Yu-Xuan Yang Hang-Hua Xu Yue Zhang Qian-Kun Sun Zhen-Wei Wang Gong-Tao Fan Hong-Wei Wang 《Nuclear Science and Techniques》 2025年第5期1-10,共10页
Energy-variable gamma-rays are produced in Laser Compton Slant-scattering mode at the Shanghai Laser Electron Gamma Source(SLEGS),a beamline of the Shanghai Synchrotron Radiation Facility(also called Shanghai Light So... Energy-variable gamma-rays are produced in Laser Compton Slant-scattering mode at the Shanghai Laser Electron Gamma Source(SLEGS),a beamline of the Shanghai Synchrotron Radiation Facility(also called Shanghai Light Source).Based on the SLEGS energy-variable gamma-ray beam,a positron generation system composed of a gamma-ray-driven section,positron-generated target,magnet separation section and positron experimental section was designed for SLEGS.Geant4 simulation results show that the energy tunable positron beam in the energy range of 1–12.9 MeV with a flux of 3.7×10^(4)–6.9×10^(5)e^(+)∕s can be produced in this positron generation system.The positron beam generation and separation provide favorable experimental conditions for conducting nondestructive positron testing on SLEGS in the future.The positron generation system is currently under construction and will be completed in 2025. 展开更多
关键词 Shanghai Laser Electron Gamma Source Monte Carlo simulation Nondestructive testing POSITRON GEANT4
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Research process on radioactive^(18)F-labelled chemical agents as positron emission tomography imaging probes for tumour detection
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作者 WU Rui ZHANG Yankun +2 位作者 LU Jiufu ZHANG Pengfei WANG Yang 《无机化学学报》 北大核心 2025年第9期1702-1718,共17页
Malignant tumours always threaten human health.For tumour diagnosis,positron emission tomography(PET)is the most sensitive and advanced imaging technique by radiotracers,such as radioactive^(18)F,^(11)C,^(64)Cu,^(68)G... Malignant tumours always threaten human health.For tumour diagnosis,positron emission tomography(PET)is the most sensitive and advanced imaging technique by radiotracers,such as radioactive^(18)F,^(11)C,^(64)Cu,^(68)Ga,and^(89)Zr.Among the radiotracers,the radioactive^(18)F-labelled chemical agent as PET probes plays a predominant role in monitoring,detecting,treating,and predicting tumours due to its perfect half-life.In this paper,the^(18)F-labelled chemical materials as PET probes are systematically summarized.First,we introduce various radionuclides of PET and elaborate on the mechanism of PET imaging.It highlights the^(18)F-labelled chemical agents used as PET probes,including[^(18)F]-2-deoxy-2-[^(18)F]fluoro-D-glucose([^(18)F]-FDG),^(18)F-labelled amino acids,^(18)F-labelled nucleic acids,^(18)F-labelled receptors,^(18)F-labelled reporter genes,and^(18)F-labelled hypoxia agents.In addition,some PET probes with metal as a supplementary element are introduced briefly.Meanwhile,the^(18)F-labelled nanoparticles for the PET probe and the multi-modality imaging probe are summarized in detail.The approach and strategies for the fabrication of^(18)F-labelled PET probes are also described briefly.The future development of the PET probe is also prospected.The development and application of^(18)F-labelled PET probes will expand our knowledge and shed light on the diagnosis and theranostics of tumours. 展开更多
关键词 ^(18)F RADIOACTIVE IMAGING positron emission tomography LABELLED TUMOUR
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Advances in 18F-fluorodeoxyglucose positron emission tomography/computed tomography for soft tissue sarcomas
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作者 Yan-Lin Zhu Yi-Wen Sun +2 位作者 Yu-Chen Ge Jian He Ru-Tian Li 《World Journal of Radiology》 2025年第7期6-16,共11页
Soft tissue sarcomas(STS)are rare malignant tumors originating from mesoder-mal tissues with a poor prognosis,accounting for approximately 1%of all malig-nancies and comprising around 50 distinct subtypes.Conventional... Soft tissue sarcomas(STS)are rare malignant tumors originating from mesoder-mal tissues with a poor prognosis,accounting for approximately 1%of all malig-nancies and comprising around 50 distinct subtypes.Conventional imaging mo-dalities,such as computed tomography(CT)and magnetic resonance imaging(MRI),primarily provide anatomical information,whereas 18F-fluorodeoxyglucose positron emission tomography/CT(18F-FDG PET/CT)integrates functional metabolic and anatomical imaging,serving as a critical complementary tool in the diagnosis and management of STS.This article reviews recent advances in the application of 18F-FDG PET/CT for STS.The advantages of 18F-FDG PET/CT in STS include:(1)Early detection of metabolic activity changes in tumors,partic-ularly when morphological alterations are insignificant;(2)Effective differen-tiation between benign and malignant soft tissue tumors,as well as aiding in distinguishing high-grade from low-grade sarcomas;(3)Identification of occult metastatic lesions,improving staging accuracy,and facilitating restaging in cases of recurrence or metastasis;(4)Utilization of parameters such as maximum stan-dardized uptake value and metabolic tumor volume to assist in tumor grading and prognostic evaluation;and(5)Monitoring treatment response to guide adjust-ments in personalized therapeutic strategies.However,18F-FDG PET/CT has limitations in diagnosis of certain STS subtypes(e.g.,myxoid liposarcoma),detection and biopsy of metastatic lymph nodes,necessitating integration with clinical evaluation and other imaging techniques.18F-FDG PET/CT is poised to play an increasingly vital role in the precision diagnosis and treatment of STS. 展开更多
关键词 Soft tissue sarcomas Positron radiopharmaceuticals Fluorodeoxyglucose positron emission tomography Positron emission tomography computed tomography
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Clinical Application of Positron Emission Tomography/Magnetic Resonance Imaging in Pelvic Malignant Tumors
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作者 Hui Yang Jielin Bai +5 位作者 Xuena Li Yaming Li Bulin Du Yan Cui Shu Wang Yuxiang Wang 《iRADIOLOGY》 2025年第6期421-433,共13页
Positron emission tomography/magnetic resonance imaging(PET/MRI)combines the advantages of both imaging modalities.PET/MRI demonstrates superior performance in the evaluation of the therapeutic impact,staging,diagnosi... Positron emission tomography/magnetic resonance imaging(PET/MRI)combines the advantages of both imaging modalities.PET/MRI demonstrates superior performance in the evaluation of the therapeutic impact,staging,diagnosis,and treatment planning of malignancies because of its lower radiation dose,higher contrast for soft tissues,and multiparametric functional imaging.^(18)F-fluorodeoxyglucose PET/MRI has demonstrated considerable potential in the assessment of pelvic malignancies.This review briefly describes the evolution of PET/MRI imaging technology and compares the application of PET/MRI in five common pelvic tumors,including endometrial cancer,cervical cancer,ovarian cancer,prostate cancer,and bladder cancer,with that of PET/computed tomography.Additionally,radiotracers other than^(18)F-fluorodeoxyglucose have been introduced for use in pelvic tumors.The development and application of these new tracers further enhance the clinical application of PET/MRI in precision medicine for pelvic malignant cancers.Overall,this review revealed the unique contribution of PET/MRI as a promising diagnostic instrument in the management of pelvic tumors,demonstrating its important position in future clinical practice. 展开更多
关键词 bladder cancer cervical cancer clinical application comparative study endometrial cancer ovarian cancer positron emission tomography/computed tomography positron emission tomography/magnetic resonance imaging prostate cancer
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Updates on glioblastoma multiforme:From epidemiology to imaging and artificial intelligence
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作者 M'hamed Bentourkia Redha-Alla Abdo 《Artificial Intelligence in Medical Imaging》 2025年第2期1-16,共16页
Glioblastoma multiforme(GBM)are the most aggressive and common tumors in the central nervous system.GBM are classified as grade IV according to the World Health Organization.The incidence of GBM slightly differs among... Glioblastoma multiforme(GBM)are the most aggressive and common tumors in the central nervous system.GBM are classified as grade IV according to the World Health Organization.The incidence of GBM slightly differs among countries.The etiology of GBM has not been entirely clarified.No risk factors such as smoking,chemicals or dietary can be identified for GBM.Only the exposure to high radiation dose such as radiotherapy of head and neck cancers have been reported to increase the risk of glioma tumors.In this review,the authors attempted to cover several aspects of GBM.This review was based on a collection of recent publications from different research fields but all related to GBM in order to shed the light on this disease.We highlighted the current insights of GBM in the aspects of epidemiology,pathogenesis,etiology,molecular genetics,imaging technologies,artificial intelligence and treatment.A literature review was conducted for GBM with relevant keywords.Although GBM was known since several decades,its causes are still confounding,and its early detection is often unpredictable.Since the hereditary aspect of GBM is very low,there remains as the common symptoms the interference with normal brain function,memory loss,unusual behavior,headaches and seizures.The progress in GBM treatment is not satisfactory even with the deployment of huge efforts and financial costs in many domains like gene therapy,surgery and chemoradiotherapy.Despite the rapid developments of the standard treatment for GBM,the trend of survival rate did not change among years. 展开更多
关键词 GLIOBLASTOMA Cancer Radiation therapy CHEMOTHERAPY IMAGING Positron emission tomography Magnetic resonance imaging Artificial intelligence
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Theoretical understanding of defects-driven mechanoluminescence for Pr^(3+)-doped NaNbO_(3)/LiNbO_(3)heterojunctions
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作者 Wenhao Li Minyu Jin +8 位作者 Jianhui Li Ci Wang Haizheng Shi Jinlong Nan Qingmiao Hu Baifeng Liu Lu Liu Jing Ren Jianzhong Zhang 《Journal of Rare Earths》 2025年第4期691-700,I0002,共11页
Mechano luminescence(ML),which involves the emission of light under mechanical stimuli,shows great potential in various applications such as sensing,imaging,and energy harvesting.Current research suggests that the lum... Mechano luminescence(ML),which involves the emission of light under mechanical stimuli,shows great potential in various applications such as sensing,imaging,and energy harvesting.Current research suggests that the luminescence mechanism of ML is typically connected to specific defects present within the material.In this study,we focus on the investigation of ML defects in Pr^(3+)-doped NaNbO_(3)/LiNbO_(3)heterojunctions,employing a combination of experimental and theoretical approaches.Through experimental analysis,we confirmed the presence of the heterojunction and its influence on ML intensity,and the optimal doping ratio for the heterojunction in ML was established.Furthermore,we examined the influence of varying Pr^(3+)doping concentrations on ML behavior and a proof-of-concept was demonstrated using the X-rays charged heterostructural phosphor as a stress sensor for biological applications.The position and concentration of internal defects in the ML material were scrutinized through thermo luminescence tests employing the variable heating rate method and positron annihilation.Complementing the experimental findings,theoretical simulations were conducted to elucidate the underlying mechanisms responsible for the observed ML defects.Density functional theory calculations were employed to investigate the energy levels,charge transfer processes,and lattice distortions within the heterojunctions under mechanical stress.Theoretical predictions were compared and validated against the experimental results.The integration of experimental and theoretical approaches provides a comprehensive understanding of the ML behavior of Pr^(3+)-doped NaNbO_(3)/LiNbO_(3)heterojunctions.The insights gained from this research contribute to the development of novel ML materials and pave the way for their applications in next-generation sensing and energy conversion devices. 展开更多
关键词 MECHANOLUMINESCENCE Defects First-principle calculations Positron annihilation lifetime test HETEROSTRUCTURES Rare earths
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Correction:Positron annihilation study of defect formation and evolution in matrix graphite under He ion irradiation
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作者 Hong-Xia Xu Jian-Dang Liu +8 位作者 Bang-Jiao Ye Zi-Wen Pan Jun Lin Jin-Liang Song Jian-Qing Cao Chao Yan Ying-Ping Hao Jin-Xing Cheng Qing-Bo Wang 《Nuclear Science and Techniques》 2025年第6期241-241,共1页
Correction:Nuclear Science and Techniques(2025)36:4 https://doi.org/10.1007/s41365-024-01548-5 In this article,the caption for Fig(s)1,3,and 4 was inadvert-ently truncated.The incorrect and the corrected captions are ... Correction:Nuclear Science and Techniques(2025)36:4 https://doi.org/10.1007/s41365-024-01548-5 In this article,the caption for Fig(s)1,3,and 4 was inadvert-ently truncated.The incorrect and the corrected captions are given below. 展开更多
关键词 defect formation EVOLUTION He ion irradiation positron annihilation matrix graphite
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Positron annihilation study of defect formation and evolution in matrix graphite under He ion irradiation
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作者 Hong-Xia Xu Jian-Dang Liu +8 位作者 Bang-Jiao Ye Zi-Wen Pan Jun Lin Jin-Liang Song Jian-Qing Cao Chao Yan Ying-Ping Hao Jin-Xing Cheng Qing-Bo Wang 《Nuclear Science and Techniques》 2025年第1期13-21,共9页
The stability of matrix graphite under neutron irradiation and in corrosive environments is crucial for the safe operation of molten salt reactors(MSRs).Raman spectroscopy and a slow positron beam were employed to inv... The stability of matrix graphite under neutron irradiation and in corrosive environments is crucial for the safe operation of molten salt reactors(MSRs).Raman spectroscopy and a slow positron beam were employed to investigate the effects of He ion irradiation fluences and subsequent annealing on the microstructure and defects of the matrix graphite.He ions with 500 keV energy and fluences ranging from 1.1×10^(15)ions∕cm^(2)to 3.5×10^(17)ions∕cm^(2)were used to simulate neutron irradiation at 300 K.The samples with an irradiation fluence of 3.5×10^(16)ions∕cm^(2)were subjected to isochronal annealing at different temperatures(573 K,873 K and 1173 K)for 3 h.The Raman results revealed that the D peak gradually increased,whereas the intrinsic G peak decreased with increasing irradiation fluence.At the same irradiation fluence,the D peak gradually decreased,whereas the intrinsic G peak increased with increasing annealing temperature.Slow positron beam analysis demonstrated that the density or size of irradiation defects(vacancy type)increased with higher irradiation fluence,but decreased rapidly with increasing annealing temperature.The Raman spectral analysis of sample cross sections subjected to high irradiation fluences revealed the emergence of amorphization precisely at the depth where ion damage was most pronounced,whereas the surface retained its crystalline structure.Raman and positron annihilation analyses indicated that the matrix graphite exhibited good irradiation resistance to He ions at 300 K.However,vacancy-type defects induced by He ion irradiation exhibit poor thermal stability and can be easily removed during annealing. 展开更多
关键词 GRAPHITE Positron annihilation IRRADIATION Raman spectrum
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Changing paradigms in evaluating adrenal incidentalomas:Bayesian evaluation of[^(18)F]Fluorodeoxyglucose positron emission tomography use,honed on adrenocortical carcinoma
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作者 Ioannis Ilias Georgios Meristoudis 《World Journal of Clinical Oncology》 2025年第6期128-133,共6页
We present the diagnostic performance of[18F]Fluorodeoxyglucose positron emission tomography(FDG PET)for adrenal incidentalomas based on lesion size and unenhanced computed tomography(CT)density in Hounsfield units(HU... We present the diagnostic performance of[18F]Fluorodeoxyglucose positron emission tomography(FDG PET)for adrenal incidentalomas based on lesion size and unenhanced computed tomography(CT)density in Hounsfield units(HU),following current literature and guidelines.A 20 HU cutoff can be applied to differentiate potentially benign from malignant lesions,particularly in ruling in or out adrenocortical carcinoma.While FDG PET provides valuable metabolic information,its likelihood ratios for a positive(LR+)or negative(LR-)result do not exceed the robust diagnostic thresholds of>10.0 or<0.1,respectively.This suggests that positron emission tomography alone is insufficient for definitive characterization and should be integrated with CT or magnetic resonance imaging to leverage their complementary anatomical and functional imaging strengths for optimal diagnostic accuracy. 展开更多
关键词 Adrenal gland neoplasms DIAGNOSIS EPIDEMIOLOGY Positron emission tomography Bayes theorem
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Multimodal Convolutional Mixer for Mild Cognitive Impairment Detection
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作者 Ovidijus Grigas Robertas Damaševicius Rytis Maskeli—unas 《Computers, Materials & Continua》 2025年第7期1805-1838,共34页
Brain imaging is important in detecting Mild Cognitive Impairment(MCI)and related dementias.Magnetic Resonance Imaging(MRI)provides structural insights,while Positron Emission Tomography(PET)evaluates metabolic activi... Brain imaging is important in detecting Mild Cognitive Impairment(MCI)and related dementias.Magnetic Resonance Imaging(MRI)provides structural insights,while Positron Emission Tomography(PET)evaluates metabolic activity,aiding in the identification of dementia-related pathologies.This study integrates multiple data modalities—T1-weighted MRI,Pittsburgh Compound B(PiB)PET scans,cognitive assessments such as Mini-Mental State Examination(MMSE),Clinical Dementia Rating(CDR)and Functional Activities Questionnaire(FAQ),blood pressure parameters,and demographic data—to improve MCI detection.The proposed improved Convolutional Mixer architecture,incorporating B-cos modules,multi-head self-attention,and a custom classifier,achieves a classification accuracy of 96.3%on the Mayo Clinic Study of Aging(MCSA)dataset(sagittal plane),outperforming state-of-the-art models by 5%–20%.On the full dataset,the model maintains a high accuracy of 94.9%,with sensitivity and specificity reaching 89.1%and 98.3%,respectively.Extensive evaluations across different imaging planes confirm that the sagittal plane offers the highest diagnostic performance,followed by axial and coronal planes.Feature visualization highlights contributions from central brain structures and lateral ventricles in differentiating MCI from cognitively normal subjects.These results demonstrate that the proposed multimodal deep learning approach improves accuracy and interpretability in MCI detection. 展开更多
关键词 Magnetic resonance imaging positron emission tomography mild cognitive impairment convolutional mixer CLASSIFICATION
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Research Progress of Microfluidics in Radiopharmaceutical Quality Control
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作者 Zhenhao Dong Qinggang He +2 位作者 Dilong Mao Jing Wang Hong Zhang 《iRADIOLOGY》 2025年第6期401-420,共20页
Radionuclide imaging is divided into positron emission tomography and single photon emission tomography and is widely used in clinical practice for diagnosis and treatment,as well as in clinical research for the devel... Radionuclide imaging is divided into positron emission tomography and single photon emission tomography and is widely used in clinical practice for diagnosis and treatment,as well as in clinical research for the development and evaluation of new therapies.Although it is a visually intuitive form of three-dimensional functional imaging,this modality requires the injection of radiopharmaceuticals labeled with positron-or gamma-emitting isotopes into patients to assess and quantify anabolism,gene expression,and other processes.For this reason,radiopharmaceuticals must undergo rigorous quality control(QC)to ensure product purity,efficacy,and safety.Traditional QC of pharmaceuticals is manual,requiring specially trained personnel,a range of expensive analytical and chemical equipment and laboratory space,the consumption of many samples,and usually a long time.Compared with ordinary pharmaceuticals,radiopharmaceuticals have the following unique characteristics:radioactivity,short lifetime,low synthesis yield,and high cost.Therefore,analytical methods and instrumentation must be exclusively developed for the QC of radiopharmaceuticals to avoid large losses owing to radioactive decay or handling.Microfluidics integrates microchannels or microchambers into several square centimeters of a microscale chip through micro-nanofabrication,allowing a precise manipulation of the fluid in microtubules,where various traditional physical,chemical,or biological experiments occur.Microfluidics is gaining attention in the field of analytical testing owing to significantly reduced consumption of samples and reagents,reduced analysis time,increased detection sensitivity,increased multiplexing,and reduced instrument size.Features such as micro size,micro volume,high sensitivity,and on-line testing have led to increasing interest in microfluidics.This review covers the development of integrated microfluidic QC devices that can automatically process,test,analyze,and calculate completed test metrics online. 展开更多
关键词 analytical testing microfluidic positron emission tomography probe quality control RADIOPHARMACEUTICAL
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